From: Richard Sandiford Date: Thu, 17 Dec 2020 00:15:11 +0000 (+0000) Subject: Add rtl-ssa X-Git-Tag: upstream/12.2.0~10767 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=73b7582775254b764fd92ddb252a33dc15872c69;p=platform%2Fupstream%2Fgcc.git Add rtl-ssa This patch adds the RTL SSA infrastructure itself. The following fwprop.c patch will make use of it. gcc/ * configure.ac: Add rtl-ssa to the list of dependence directories. * configure: Regenerate. * Makefile.in (rtl-ssa-warn): New variable. (OBJS): Add the rtl-ssa object files. * emit-rtl.h (rtl_data::ssa): New field. * rtl-ssa.h: New file. * system.h: Include when INCLUDE_FUNCTIONAL is defined. * rtl-ssa/access-utils.h: Likewise. * rtl-ssa/accesses.h: New file. * rtl-ssa/accesses.cc: Likewise. * rtl-ssa/blocks.h: New file. * rtl-ssa/blocks.cc: Likewise. * rtl-ssa/change-utils.h: Likewise. * rtl-ssa/changes.h: New file. * rtl-ssa/changes.cc: Likewise. * rtl-ssa/functions.h: New file. * rtl-ssa/functions.cc: Likewise. * rtl-ssa/insn-utils.h: Likewise. * rtl-ssa/insns.h: New file. * rtl-ssa/insns.cc: Likewise. * rtl-ssa/internals.inl: Likewise. * rtl-ssa/is-a.inl: Likewise. * rtl-ssa/member-fns.inl: Likewise. * rtl-ssa/movement.h: Likewise. --- diff --git a/gcc/Makefile.in b/gcc/Makefile.in index 89353c2..178e4ea 100644 --- a/gcc/Makefile.in +++ b/gcc/Makefile.in @@ -207,6 +207,7 @@ VALGRIND_DRIVER_DEFINES = @valgrind_path_defines@ # This is how we control whether or not the additional warnings are applied. .-warn = $(STRICT_WARN) build-warn = $(STRICT_WARN) +rtl-ssa-warn = $(STRICT_WARN) GCC_WARN_CFLAGS = $(LOOSE_WARN) $(C_LOOSE_WARN) $($(@D)-warn) $(if $(filter-out $(STRICT_WARN),$($(@D)-warn)),,$(C_STRICT_WARN)) $(NOCOMMON_FLAG) $($@-warn) GCC_WARN_CXXFLAGS = $(LOOSE_WARN) $($(@D)-warn) $(NOCOMMON_FLAG) $($@-warn) @@ -1525,6 +1526,11 @@ OBJS = \ reorg.o \ resource.o \ rtl-error.o \ + rtl-ssa/accesses.o \ + rtl-ssa/blocks.o \ + rtl-ssa/changes.o \ + rtl-ssa/functions.o \ + rtl-ssa/insns.o \ rtl-tests.o \ rtl.o \ rtlhash.o \ diff --git a/gcc/configure b/gcc/configure index eedd862..fe649b2 100755 --- a/gcc/configure +++ b/gcc/configure @@ -33265,7 +33265,7 @@ $as_echo "$as_me: executing $ac_file commands" >&6;} "depdir":C) $SHELL $ac_aux_dir/mkinstalldirs $DEPDIR ;; "gccdepdir":C) ${CONFIG_SHELL-/bin/sh} $ac_aux_dir/mkinstalldirs build/$DEPDIR - for lang in $subdirs c-family common analyzer + for lang in $subdirs c-family common analyzer rtl-ssa do ${CONFIG_SHELL-/bin/sh} $ac_aux_dir/mkinstalldirs $lang/$DEPDIR done ;; diff --git a/gcc/configure.ac b/gcc/configure.ac index ee982be..3755722 100644 --- a/gcc/configure.ac +++ b/gcc/configure.ac @@ -1242,7 +1242,7 @@ AC_CHECK_HEADERS(ext/hash_map) ZW_CREATE_DEPDIR AC_CONFIG_COMMANDS([gccdepdir],[ ${CONFIG_SHELL-/bin/sh} $ac_aux_dir/mkinstalldirs build/$DEPDIR - for lang in $subdirs c-family common analyzer + for lang in $subdirs c-family common analyzer rtl-ssa do ${CONFIG_SHELL-/bin/sh} $ac_aux_dir/mkinstalldirs $lang/$DEPDIR done], [subdirs="$subdirs" ac_aux_dir=$ac_aux_dir DEPDIR=$DEPDIR]) diff --git a/gcc/emit-rtl.h b/gcc/emit-rtl.h index 4658c4a..b20cd76 100644 --- a/gcc/emit-rtl.h +++ b/gcc/emit-rtl.h @@ -23,6 +23,7 @@ along with GCC; see the file COPYING3. If not see class temp_slot; typedef class temp_slot *temp_slot_p; class predefined_function_abi; +namespace rtl_ssa { class function_info; } /* Information mainlined about RTL representation of incoming arguments. */ struct GTY(()) incoming_args { @@ -73,6 +74,8 @@ struct GTY(()) rtl_data { different ABIs. */ const predefined_function_abi *GTY((skip)) abi; + rtl_ssa::function_info *GTY((skip)) ssa; + /* For function.c */ /* # of bytes of outgoing arguments. If ACCUMULATE_OUTGOING_ARGS is diff --git a/gcc/rtl-ssa.h b/gcc/rtl-ssa.h new file mode 100644 index 0000000..60cdad0 --- /dev/null +++ b/gcc/rtl-ssa.h @@ -0,0 +1,71 @@ +// On-the-side RTL SSA representation -*- C++ -*- +// Copyright (C) 2020 Free Software Foundation, Inc. +// +// This file is part of GCC. +// +// GCC is free software; you can redistribute it and/or modify it under +// the terms of the GNU General Public License as published by the Free +// Software Foundation; either version 3, or (at your option) any later +// version. +// +// GCC is distributed in the hope that it will be useful, but WITHOUT ANY +// WARRANTY; without even the implied warranty of MERCHANTABILITY or +// FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License +// for more details. +// +// You should have received a copy of the GNU General Public License +// along with GCC; see the file COPYING3. If not see +// . + +#ifndef GCC_RTL_SSA_H +#define GCC_RTL_SSA_H 1 + +// This is an aggregation header file. This means it should contain only +// other include files. + +#if 0 +// Files that use this one should first have: +#define INCLUDE_ALGORITHM +#define INCLUDE_FUNCTIONAL +#include "config.h" +#include "system.h" +#include "coretypes.h" +#include "backend.h" +#include "rtl.h" +#include "df.h" +#endif + +// Needed by splay-tree-utils.h and directly by rtl-ssa. +#include "pretty-print.h" + +// Needed directly by recog.h. +#include "insn-config.h" + +// Needed directly by rtl-ssa. +#include "splay-tree-utils.h" +#include "recog.h" +#include "regs.h" +#include "function-abi.h" +#include "obstack-utils.h" +#include "mux-utils.h" +#include "rtlanal.h" + +// Provides the global crtl->ssa. +#include "tm_p.h" +#include "memmodel.h" +#include "emit-rtl.h" + +// The rtl-ssa files themselves. +#include "rtl-ssa/accesses.h" +#include "rtl-ssa/insns.h" +#include "rtl-ssa/blocks.h" +#include "rtl-ssa/changes.h" +#include "rtl-ssa/functions.h" +#include "rtl-ssa/is-a.inl" +#include "rtl-ssa/access-utils.h" +#include "rtl-ssa/insn-utils.h" +#include "rtl-ssa/movement.h" +#include "rtl-ssa/change-utils.h" +#include "rtl-ssa/member-fns.inl" + +#endif diff --git a/gcc/rtl-ssa/access-utils.h b/gcc/rtl-ssa/access-utils.h new file mode 100644 index 0000000..b200e34 --- /dev/null +++ b/gcc/rtl-ssa/access-utils.h @@ -0,0 +1,553 @@ +// Access-related utilities for RTL SSA -*- C++ -*- +// Copyright (C) 2020 Free Software Foundation, Inc. +// +// This file is part of GCC. +// +// GCC is free software; you can redistribute it and/or modify it under +// the terms of the GNU General Public License as published by the Free +// Software Foundation; either version 3, or (at your option) any later +// version. +// +// GCC is distributed in the hope that it will be useful, but WITHOUT ANY +// WARRANTY; without even the implied warranty of MERCHANTABILITY or +// FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License +// for more details. +// +// You should have received a copy of the GNU General Public License +// along with GCC; see the file COPYING3. If not see +// . + +namespace rtl_ssa { + +// Return a referene to the whole of register REGNO. +inline resource_info +full_register (unsigned int regno) +{ + return { reg_raw_mode[regno], regno }; +} + +// Return true if sorted array ACCESSES includes an access to hard registers. +inline bool +accesses_include_hard_registers (const access_array &accesses) +{ + return accesses.size () && HARD_REGISTER_NUM_P (accesses.front ()->regno ()); +} + +// Return true if sorted array ACCESSES includes an access to memory. +inline bool +accesses_include_memory (const access_array &accesses) +{ + return accesses.size () && accesses.back ()->is_mem (); +} + +// If sorted array ACCESSES includes an access to memory, return the access, +// otherwise return null. +template +inline auto +memory_access (T accesses) -> decltype (accesses[0]) +{ + if (accesses.size () && accesses.back ()->is_mem ()) + return accesses.back (); + return nullptr; +} + +// If sorted array ACCESSES includes a reference to REGNO, return the +// access, otherwise return null. +template +inline auto +find_access (T accesses, unsigned int regno) -> decltype (accesses[0]) +{ + unsigned int start = 0; + unsigned int end = accesses.size (); + while (start < end) + { + unsigned int mid = (start + end) / 2; + unsigned int found = accesses[mid]->regno (); + if (found == regno) + return accesses[mid]; + if (found < regno) + start = mid + 1; + else + end = mid; + } + return nullptr; +} + +// If sorted array ACCESSES includes a reference to REGNO, return the +// index of the access, otherwise return -1. +inline int +find_access_index (access_array accesses, unsigned int regno) +{ + unsigned int start = 0; + unsigned int end = accesses.size (); + while (start < end) + { + unsigned int mid = (start + end) / 2; + unsigned int found = accesses[mid]->regno (); + if (found == regno) + return mid; + if (found < regno) + start = mid + 1; + else + end = mid; + } + return -1; +} + +// If ACCESS is a set whose result is used by at least one instruction, +// return the access as a set_info, otherwise return null. +inline const set_info * +set_with_nondebug_insn_uses (const access_info *access) +{ + if (access->is_set_with_nondebug_insn_uses ()) + // No need for as_a; this test is just as definitive. + return static_cast (access); + return nullptr; +} + +// A non-const version of the above. +inline set_info * +set_with_nondebug_insn_uses (access_info *access) +{ + if (access->is_set_with_nondebug_insn_uses ()) + return static_cast (access); + return nullptr; +} + +// Return true if SET is the only set of SET->resource () and if it +// dominates all uses (excluding uses of SET->resource () at points +// where SET->resource () is always undefined). +inline bool +is_single_dominating_def (const set_info *set) +{ + return set->is_first_def () && set->is_last_def (); +} + +// SET is known to be available on entry to BB. Return true if it is +// also available on exit from BB. (The value might or might not be live.) +inline bool +remains_available_on_exit (const set_info *set, bb_info *bb) +{ + return (set->is_last_def () + || *set->next_def ()->insn () > *bb->end_insn ()); +} + +// ACCESS is known to be associated with an instruction rather than +// a phi node. Return which instruction that is. +inline insn_info * +access_insn (const access_info *access) +{ + // In release builds this function reduces to a single pointer reference. + if (auto *def = dyn_cast (access)) + return def->insn (); + return as_a (access)->insn (); +} + +// If ACCESS records a use, return the value that it uses. If ACCESS records +// a set, return that set. If ACCESS records a clobber, return null. +inline const set_info * +access_value (const access_info *access) +{ + if (!access) + return nullptr; + + if (auto *use = dyn_cast (access)) + return use->def (); + + return dyn_cast (access); +} + +// A non-const version of the above. +inline set_info * +access_value (access_info *access) +{ + auto *const_access = const_cast (access); + return const_cast (access_value (const_access)); +} + +// If ACCESS is a degenerate phi, return the set_info that defines its input, +// otherwise return ACCESS itself. +template +inline const T * +look_through_degenerate_phi (const T *access) +{ + if (auto *phi = dyn_cast (access)) + if (phi->is_degenerate ()) + return phi->input_value (0); + return access; +} + +// A non-const version of the above. +template +inline T * +look_through_degenerate_phi (T *access) +{ + auto *const_access = const_cast (access); + return const_cast (look_through_degenerate_phi (const_access)); +} + +// If CLOBBER is in a group, return the first clobber in the group, +// otherwise return CLOBBER itself. +inline clobber_info * +first_clobber_in_group (clobber_info *clobber) +{ + if (clobber->is_in_group ()) + return clobber->group ()->first_clobber (); + return clobber; +} + +// If CLOBBER is in a group, return the last clobber in the group, +// otherwise return CLOBBER itself. +inline clobber_info * +last_clobber_in_group (clobber_info *clobber) +{ + if (clobber->is_in_group ()) + return clobber->group ()->last_clobber (); + return clobber; +} + +// If DEF is a clobber in a group, return the containing group, +// otherwise return DEF. +inline def_mux +clobber_group_or_single_def (def_info *def) +{ + if (auto *clobber = dyn_cast (def)) + if (clobber->is_in_group ()) + return clobber->group (); + return def; +} + +// Return the first definition associated with NODE. If NODE holds +// a single set, the result is that set. If NODE holds a clobber_group, +// the result is the first clobber in the group. +inline def_info * +first_def (def_node *node) +{ + return node->first_def (); +} + +// Likewise for something that is either a node or a single definition. +inline def_info * +first_def (def_mux mux) +{ + return mux.first_def (); +} + +// Return the last definition associated with NODE. If NODE holds +// a single set, the result is that set. If NODE holds a clobber_group, +// the result is the last clobber in the group. +inline def_info * +last_def (def_node *node) +{ + if (auto *group = dyn_cast (node)) + return group->last_clobber (); + return node->first_def (); +} + +// Likewise for something that is either a node or a single definition. +inline def_info * +last_def (def_mux mux) +{ + return mux.last_def (); +} + +int lookup_use (splay_tree &, insn_info *); +int lookup_def (def_splay_tree &, insn_info *); +int lookup_clobber (clobber_tree &, insn_info *); +int lookup_call_clobbers (insn_call_clobbers_tree &, insn_info *); + +// Search backwards from immediately before INSN for the first instruction +// recorded in TREE, ignoring any instruction I for which IGNORE (I) is true. +// Return null if no such instruction exists. +template +insn_info * +prev_call_clobbers_ignoring (insn_call_clobbers_tree &tree, insn_info *insn, + IgnorePredicate ignore) +{ + if (!tree) + return nullptr; + + int comparison = lookup_call_clobbers (tree, insn); + while (comparison <= 0 || ignore (tree->insn ())) + { + if (!tree.splay_prev_node ()) + return nullptr; + + comparison = 1; + } + return tree->insn (); +} + +// Search forwards from immediately after INSN for the first instruction +// recorded in TREE, ignoring any instruction I for which IGNORE (I) is true. +// Return null if no such instruction exists. +template +insn_info * +next_call_clobbers_ignoring (insn_call_clobbers_tree &tree, insn_info *insn, + IgnorePredicate ignore) +{ + if (!tree) + return nullptr; + + int comparison = lookup_call_clobbers (tree, insn); + while (comparison >= 0 || ignore (tree->insn ())) + { + if (!tree.splay_next_node ()) + return nullptr; + + comparison = -1; + } + return tree->insn (); +} + +// If ACCESS is a set, return the first use of ACCESS by a nondebug insn I +// for which IGNORE (I) is false. Return null if ACCESS is not a set or if +// no such use exists. +template +inline use_info * +first_nondebug_insn_use_ignoring (const access_info *access, + IgnorePredicate ignore) +{ + if (const set_info *set = set_with_nondebug_insn_uses (access)) + { + // Written this way to emphasize to the compiler that first_use + // must be nonnull in this situation. + use_info *use = set->first_use (); + do + { + if (!ignore (use->insn ())) + return use; + use = use->next_nondebug_insn_use (); + } + while (use); + } + return nullptr; +} + +// If ACCESS is a set, return the last use of ACCESS by a nondebug insn I for +// which IGNORE (I) is false. Return null if ACCESS is not a set or if no +// such use exists. +template +inline use_info * +last_nondebug_insn_use_ignoring (const access_info *access, + IgnorePredicate ignore) +{ + if (const set_info *set = set_with_nondebug_insn_uses (access)) + { + // Written this way to emphasize to the compiler that + // last_nondebug_insn_use must be nonnull in this situation. + use_info *use = set->last_nondebug_insn_use (); + do + { + if (!ignore (use->insn ())) + return use; + use = use->prev_use (); + } + while (use); + } + return nullptr; +} + +// If DEF is null, return null. +// +// Otherwise, search backwards for an access to DEF->resource (), starting at +// the end of DEF's live range. Ignore clobbers if IGNORE_CLOBBERS_SETTING +// is YES, otherwise treat them like any other access. Also ignore any +// access A for which IGNORE (access_insn (A)) is true. +// +// Thus if DEF is a set that is used by nondebug insns, the first access +// that the function considers is the last such use of the set. Otherwise, +// the first access that the function considers is DEF itself. +// +// Return the access found, or null if there is no access that meets +// the criteria. +// +// Note that this function does not consider separately-recorded call clobbers, +// although such clobbers are only relevant if IGNORE_CLOBBERS_SETTING is NO. +template +access_info * +last_access_ignoring (def_info *def, ignore_clobbers ignore_clobbers_setting, + IgnorePredicate ignore) +{ + while (def) + { + auto *clobber = dyn_cast (def); + if (clobber && ignore_clobbers_setting == ignore_clobbers::YES) + def = first_clobber_in_group (clobber); + else + { + if (use_info *use = last_nondebug_insn_use_ignoring (def, ignore)) + return use; + + insn_info *insn = def->insn (); + if (!ignore (insn)) + return def; + } + def = def->prev_def (); + } + return nullptr; +} + +// Search backwards for an access to DEF->resource (), starting +// immediately before the point at which DEF occurs. Ignore clobbers +// if IGNORE_CLOBBERS_SETTING is YES, otherwise treat them like any other +// access. Also ignore any access A for which IGNORE (access_insn (A)) +// is true. +// +// Thus if DEF->insn () uses DEF->resource (), that use is the first access +// that the function considers, since an instruction's uses occur strictly +// before its definitions. +// +// Note that this function does not consider separately-recorded call clobbers, +// although such clobbers are only relevant if IGNORE_CLOBBERS_SETTING is NO. +template +inline access_info * +prev_access_ignoring (def_info *def, ignore_clobbers ignore_clobbers_setting, + IgnorePredicate ignore) +{ + return last_access_ignoring (def->prev_def (), ignore_clobbers_setting, + ignore); +} + +// If DEF is null, return null. +// +// Otherwise, search forwards for a definition of DEF->resource (), +// starting at DEF itself. Ignore clobbers if IGNORE_CLOBBERS_SETTING +// is YES, otherwise treat them like any other access. Also ignore any +// definition D for which IGNORE (D->insn ()) is true. +// +// Return the definition found, or null if there is no access that meets +// the criteria. +// +// Note that this function does not consider separately-recorded call clobbers, +// although such clobbers are only relevant if IGNORE_CLOBBERS_SETTING is NO. +template +def_info * +first_def_ignoring (def_info *def, ignore_clobbers ignore_clobbers_setting, + IgnorePredicate ignore) +{ + while (def) + { + auto *clobber = dyn_cast (def); + if (clobber && ignore_clobbers_setting == ignore_clobbers::YES) + def = last_clobber_in_group (clobber); + else if (!ignore (def->insn ())) + return def; + + def = def->next_def (); + } + return nullptr; +} + +// Search forwards for the next access to DEF->resource (), +// starting immediately after DEF's instruction. Ignore clobbers if +// IGNORE_CLOBBERS_SETTING is YES, otherwise treat them like any other access. +// Also ignore any access A for which IGNORE (access_insn (A)) is true; +// in this context, ignoring a set includes ignoring all uses of the set. +// +// Thus if DEF is a set with uses by nondebug insns, the first access that the +// function considers is the first such use of the set. +// +// Return the access found, or null if there is no access that meets the +// criteria. +// +// Note that this function does not consider separately-recorded call clobbers, +// although such clobbers are only relevant if IGNORE_CLOBBERS_SETTING is NO. +template +access_info * +next_access_ignoring (def_info *def, ignore_clobbers ignore_clobbers_setting, + IgnorePredicate ignore) +{ + if (use_info *use = first_nondebug_insn_use_ignoring (def, ignore)) + return use; + + return first_def_ignoring (def->next_def (), ignore_clobbers_setting, + ignore); +} + +// Return true if ACCESS1 should before ACCESS2 in an access_array. +inline bool +compare_access_infos (const access_info *access1, const access_info *access2) +{ + gcc_checking_assert (access1 == access2 + || access1->regno () != access2->regno ()); + return access1->regno () < access2->regno (); +} + +// Sort [BEGIN, END) into ascending regno order. The sequence must have +// at most one access to a given a regno. +inline void +sort_accesses (access_info **begin, access_info **end) +{ + auto count = end - begin; + if (count <= 1) + return; + + if (count == 2) + { + gcc_checking_assert (begin[0]->regno () != begin[1]->regno ()); + if (begin[0]->regno () > begin[1]->regno ()) + std::swap (begin[0], begin[1]); + return; + } + + std::sort (begin, end, compare_access_infos); +} + +// Sort the accesses in CONTAINER, which contains pointers to access_infos. +template +inline void +sort_accesses (T &container) +{ + return sort_accesses (container.begin (), container.end ()); +} + +// The underlying non-template implementation of merge_access_arrays. +access_array merge_access_arrays_base (obstack_watermark &, access_array, + access_array); +// Merge access arrays ACCESSES1 and ACCESSES2, including the allocation +// in the area governed by WATERMARK. Return an invalid access_array if +// ACCESSES1 and ACCESSES2 contain conflicting accesses to the same resource. +// +// T can be an access_array, a def_array or a use_array. +template +inline T +merge_access_arrays (obstack_watermark &watermark, T accesses1, T accesses2) +{ + return T (merge_access_arrays_base (watermark, accesses1, accesses2)); +} + +// The underlying non-template implementation of insert_access. +access_array insert_access_base (obstack_watermark &, access_info *, + access_array); + +// Return a new access_array that contains the result of inserting ACCESS1 +// into sorted access array ACCESSES2. Allocate the returned array in the +// area governed by WATERMARK. Return an invalid access_array if ACCESSES2 +// contains a conflicting access to the same resource as ACCESS1. +// +// T can be an access_array, a def_array or a use_array. +template +inline T +insert_access (obstack_watermark &watermark, + typename T::value_type access1, T accesses2) +{ + return T (insert_access_base (watermark, access1, accesses2)); +} + +// The underlying non-template implementation of remove_note_accesses. +access_array remove_note_accesses_base (obstack_watermark &, access_array); + +// If ACCESSES contains accesses that only occur in notes, return a new +// array without such accesses, allocating it in the area governed by +// WATERMARK. Return ACCESSES itself otherwise. +// +// T can be an access_array, a def_array or a use_array. +template +inline T +remove_note_accesses (obstack_watermark &watermark, T accesses) +{ + return T (remove_note_accesses_base (watermark, accesses)); +} + +} diff --git a/gcc/rtl-ssa/accesses.cc b/gcc/rtl-ssa/accesses.cc new file mode 100644 index 0000000..6a28007 --- /dev/null +++ b/gcc/rtl-ssa/accesses.cc @@ -0,0 +1,1594 @@ +// Implementation of access-related functions for RTL SSA -*- C++ -*- +// Copyright (C) 2020 Free Software Foundation, Inc. +// +// This file is part of GCC. +// +// GCC is free software; you can redistribute it and/or modify it under +// the terms of the GNU General Public License as published by the Free +// Software Foundation; either version 3, or (at your option) any later +// version. +// +// GCC is distributed in the hope that it will be useful, but WITHOUT ANY +// WARRANTY; without even the implied warranty of MERCHANTABILITY or +// FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License +// for more details. +// +// You should have received a copy of the GNU General Public License +// along with GCC; see the file COPYING3. If not see +// . + +#define INCLUDE_ALGORITHM +#define INCLUDE_FUNCTIONAL +#include "config.h" +#include "system.h" +#include "coretypes.h" +#include "backend.h" +#include "rtl.h" +#include "df.h" +#include "rtl-ssa.h" +#include "rtl-ssa/internals.inl" + +using namespace rtl_ssa; + +// This clobber belongs to a clobber_group but m_group appears to be +// out of date. Update it and return the new (correct) value. +clobber_group * +clobber_info::recompute_group () +{ + using splay_tree = clobber_info::splay_tree; + + // Splay this clobber to the root of the tree while searching for a node + // that has the correct group. The root always has the correct group, + // so the search always breaks early and does not install this clobber + // as the root. + clobber_info *cursor = m_parent; + auto find_group = [](clobber_info *node, unsigned int) + { + return node->m_group->has_been_superceded () ? nullptr : node->m_group; + }; + clobber_group *group = splay_tree::splay_and_search (this, nullptr, + find_group); + gcc_checking_assert (m_parent); + + // If the previous splay operation did anything, this clobber is now an + // ancestor of CURSOR, and all the nodes inbetween have a stale group. + // Since we have visited the nodes, we might as well update them too. + // + // If the previous splay operation did nothing, start the update from + // this clobber instead. In that case we change at most two clobbers: + // this clobber and possibly its parent. + if (cursor == m_parent) + cursor = this; + + // Walk up the tree from CURSOR updating clobbers that need it. + // This walk always includes this clobber. + while (cursor->m_group != group) + { + cursor->m_group = group; + cursor = cursor->m_parent; + } + + gcc_checking_assert (m_group == group); + return group; +} + +// See the comment above the declaration. +void +resource_info::print_identifier (pretty_printer *pp) const +{ + if (is_mem ()) + pp_string (pp, "mem"); + else + { + char tmp[3 * sizeof (regno) + 2]; + snprintf (tmp, sizeof (tmp), "r%d", regno); + pp_string (pp, tmp); + } +} + +// See the comment above the declaration. +void +resource_info::print_context (pretty_printer *pp) const +{ + if (HARD_REGISTER_NUM_P (regno)) + { + if (const char *name = reg_names[regno]) + { + pp_space (pp); + pp_left_paren (pp); + pp_string (pp, name); + if (mode != E_BLKmode) + { + pp_colon (pp); + pp_string (pp, GET_MODE_NAME (mode)); + } + pp_right_paren (pp); + } + } + else if (is_reg ()) + { + pp_space (pp); + pp_left_paren (pp); + if (mode != E_BLKmode) + { + pp_string (pp, GET_MODE_NAME (mode)); + pp_space (pp); + } + pp_string (pp, "pseudo"); + pp_right_paren (pp); + } +} + +// See the comment above the declaration. +void +resource_info::print (pretty_printer *pp) const +{ + print_identifier (pp); + print_context (pp); +} + +// Some properties can naturally be described using adjectives that attach +// to nouns like "use" or "definition". Print such adjectives to PP. +void +access_info::print_prefix_flags (pretty_printer *pp) const +{ + if (m_is_temp) + pp_string (pp, "temporary "); + if (m_has_been_superceded) + pp_string (pp, "superceded "); +} + +// Print properties not handled by print_prefix_flags to PP, putting +// each property on a new line indented by two extra spaces. +void +access_info::print_properties_on_new_lines (pretty_printer *pp) const +{ + if (m_is_pre_post_modify) + { + pp_newline_and_indent (pp, 2); + pp_string (pp, "set by a pre/post-modify"); + pp_indentation (pp) -= 2; + } + if (m_includes_address_uses) + { + pp_newline_and_indent (pp, 2); + pp_string (pp, "appears inside an address"); + pp_indentation (pp) -= 2; + } + if (m_includes_read_writes) + { + pp_newline_and_indent (pp, 2); + pp_string (pp, "appears in a read/write context"); + pp_indentation (pp) -= 2; + } + if (m_includes_subregs) + { + pp_newline_and_indent (pp, 2); + pp_string (pp, "appears inside a subreg"); + pp_indentation (pp) -= 2; + } +} + +// Return true if there are no known issues with the integrity of the +// link information. +inline bool +use_info::check_integrity () +{ + auto subsequence_id = [](use_info *use) + { + if (use->is_in_nondebug_insn ()) + return 1; + if (use->is_in_debug_insn ()) + return 2; + return 3; + }; + + use_info *prev = prev_use (); + use_info *next = next_use (); + + if (prev && subsequence_id (prev) > subsequence_id (this)) + return false; + if (next && subsequence_id (next) < subsequence_id (this)) + return false; + if (m_is_last_nondebug_insn_use != calculate_is_last_nondebug_insn_use ()) + return false; + + if (!prev && last_use ()->next_use ()) + return false; + if (!next) + if (use_info *use = last_nondebug_insn_use ()) + if (!use->m_is_last_nondebug_insn_use) + return false; + + return true; +} + +// See the comment above the declaration. +void +use_info::print_location (pretty_printer *pp) const +{ + if (is_in_phi ()) + pp_access (pp, phi (), PP_ACCESS_INCLUDE_LOCATION); + else + insn ()->print_identifier_and_location (pp); +} + +// See the comment above the declaration. +void +use_info::print_def (pretty_printer *pp) const +{ + if (const set_info *set = def ()) + pp_access (pp, set, 0); + else + { + pp_string (pp, "undefined "); + resource ().print (pp); + } +} + +// See the comment above the declaration. +void +use_info::print (pretty_printer *pp, unsigned int flags) const +{ + print_prefix_flags (pp); + + const set_info *set = def (); + if (set && set->mode () != mode ()) + { + pp_string (pp, GET_MODE_NAME (mode ())); + pp_space (pp); + } + + pp_string (pp, "use of "); + print_def (pp); + if (flags & PP_ACCESS_INCLUDE_LOCATION) + { + pp_string (pp, " by "); + print_location (pp); + } + if (set && (flags & PP_ACCESS_INCLUDE_LINKS)) + { + pp_newline_and_indent (pp, 2); + pp_string (pp, "defined in "); + set->insn ()->print_location (pp); + pp_indentation (pp) -= 2; + } + if (flags & PP_ACCESS_INCLUDE_PROPERTIES) + print_properties_on_new_lines (pp); +} + +// See the comment above the declaration. +void +def_info::print_identifier (pretty_printer *pp) const +{ + resource ().print_identifier (pp); + pp_colon (pp); + insn ()->print_identifier (pp); + resource ().print_context (pp); +} + +// See the comment above the declaration. +void +def_info::print_location (pretty_printer *pp) const +{ + insn ()->print_identifier_and_location (pp); +} + +// See the comment above the declaration. +void +clobber_info::print (pretty_printer *pp, unsigned int flags) const +{ + print_prefix_flags (pp); + if (is_call_clobber ()) + pp_string (pp, "call "); + pp_string (pp, "clobber "); + print_identifier (pp); + if (flags & PP_ACCESS_INCLUDE_LOCATION) + { + pp_string (pp, " in "); + insn ()->print_location (pp); + } + if (flags & PP_ACCESS_INCLUDE_PROPERTIES) + print_properties_on_new_lines (pp); +} + +// See the comment above the declaration. +void +set_info::print_uses_on_new_lines (pretty_printer *pp) const +{ + for (const use_info *use : all_uses ()) + { + pp_newline_and_indent (pp, 2); + if (use->is_live_out_use ()) + { + pp_string (pp, "live out from "); + use->insn ()->print_location (pp); + } + else + { + pp_string (pp, "used by "); + use->print_location (pp); + } + pp_indentation (pp) -= 2; + } + if (m_use_tree) + { + pp_newline_and_indent (pp, 2); + pp_string (pp, "splay tree:"); + pp_newline_and_indent (pp, 2); + auto print_use = [](pretty_printer *pp, + splay_tree_node *node) + { + pp_string (pp, "use by "); + node->value ()->print_location (pp); + }; + m_use_tree.print (pp, m_use_tree.root (), print_use); + pp_indentation (pp) -= 4; + } +} + +// See the comment above the declaration. +void +set_info::print (pretty_printer *pp, unsigned int flags) const +{ + print_prefix_flags (pp); + pp_string (pp, "set "); + print_identifier (pp); + if (flags & PP_ACCESS_INCLUDE_LOCATION) + { + pp_string (pp, " in "); + insn ()->print_location (pp); + } + if (flags & PP_ACCESS_INCLUDE_PROPERTIES) + print_properties_on_new_lines (pp); + if (flags & PP_ACCESS_INCLUDE_LINKS) + print_uses_on_new_lines (pp); +} + +// See the comment above the declaration. +void +phi_info::print (pretty_printer *pp, unsigned int flags) const +{ + print_prefix_flags (pp); + pp_string (pp, "phi node "); + print_identifier (pp); + if (flags & PP_ACCESS_INCLUDE_LOCATION) + { + pp_string (pp, " in "); + insn ()->print_location (pp); + } + + if (flags & PP_ACCESS_INCLUDE_PROPERTIES) + print_properties_on_new_lines (pp); + + if (flags & PP_ACCESS_INCLUDE_LINKS) + { + basic_block cfg_bb = bb ()->cfg_bb (); + pp_newline_and_indent (pp, 2); + pp_string (pp, "inputs:"); + unsigned int i = 0; + for (const use_info *input : inputs ()) + { + basic_block pred_cfg_bb = EDGE_PRED (cfg_bb, i)->src; + pp_newline_and_indent (pp, 2); + pp_string (pp, "bb"); + pp_decimal_int (pp, pred_cfg_bb->index); + pp_colon (pp); + pp_space (pp); + input->print_def (pp); + pp_indentation (pp) -= 2; + i += 1; + } + pp_indentation (pp) -= 2; + + print_uses_on_new_lines (pp); + } +} + +// See the comment above the declaration. +void +set_node::print (pretty_printer *pp) const +{ + pp_access (pp, first_def ()); +} + +// See the comment above the declaration. +void +clobber_group::print (pretty_printer *pp) const +{ + auto print_clobber = [](pretty_printer *pp, const def_info *clobber) + { + pp_access (pp, clobber); + }; + pp_string (pp, "grouped clobber"); + for (const def_info *clobber : clobbers ()) + { + pp_newline_and_indent (pp, 2); + print_clobber (pp, clobber); + pp_indentation (pp) -= 2; + } + pp_newline_and_indent (pp, 2); + pp_string (pp, "splay tree"); + pp_newline_and_indent (pp, 2); + m_clobber_tree.print (pp, print_clobber); + pp_indentation (pp) -= 4; +} + +// Return a clobber_group for CLOBBER, creating one if CLOBBER doesn't +// already belong to a group. +clobber_group * +function_info::need_clobber_group (clobber_info *clobber) +{ + if (clobber->is_in_group ()) + return clobber->group (); + return allocate (clobber); +} + +// Return a def_node for inserting DEF into the associated resource's +// splay tree. Use a clobber_group if DEF is a clobber and a set_node +// otherwise. +def_node * +function_info::need_def_node (def_info *def) +{ + if (auto *clobber = dyn_cast (def)) + return need_clobber_group (clobber); + return allocate (as_a (def)); +} + +// LAST is the last thing to define LAST->resource (), and is where any +// splay tree root for LAST->resource () is stored. Require such a splay tree +// to exist, creating a new one if necessary. Return the root of the tree. +// +// The caller must call LAST->set_splay_root after it has finished with +// the splay tree. +def_splay_tree +function_info::need_def_splay_tree (def_info *last) +{ + if (def_node *root = last->splay_root ()) + return root; + + // Use a left-spine rooted at the last node. + def_node *root = need_def_node (last); + def_node *parent = root; + while (def_info *prev = first_def (parent)->prev_def ()) + { + def_node *node = need_def_node (prev); + def_splay_tree::insert_child (parent, 0, node); + parent = node; + } + return root; +} + +// Search TREE for either: +// +// - a set_info at INSN or +// - a clobber_group whose range includes INSN +// +// If such a node exists, install it as the root of TREE and return 0. +// Otherwise arbitrarily choose between: +// +// (1) Installing the closest preceding node as the root and returning 1. +// (2) Installing the closest following node as the root and returning -1. +// +// Note that this routine should not be used to check whether INSN +// itself defines a resource; that can be checked more cheaply using +// find_access_index. +int +rtl_ssa::lookup_def (def_splay_tree &tree, insn_info *insn) +{ + auto go_left = [&](def_node *node) + { + return *insn < *first_def (node)->insn (); + }; + auto go_right = [&](def_node *node) + { + return *insn > *last_def (node)->insn (); + }; + return tree.lookup (go_left, go_right); +} + +// Search TREE for a clobber in INSN. If such a clobber exists, install +// it as the root of TREE and return 0. Otherwise arbitrarily choose between: +// +// (1) Installing the closest preceding clobber as the root and returning 1. +// (2) Installing the closest following clobber as the root and returning -1. +int +rtl_ssa::lookup_clobber (clobber_tree &tree, insn_info *insn) +{ + auto compare = [&](clobber_info *clobber) + { + return insn->compare_with (clobber->insn ()); + }; + return tree.lookup (compare); +} + +// Search for a definition of RESOURCE at INSN and return the result of +// the search as a def_lookup. See the comment above the class for more +// details. +def_lookup +function_info::find_def (resource_info resource, insn_info *insn) +{ + def_info *first = m_defs[resource.regno + 1]; + if (!first) + // There are no nodes. The comparison result is pretty meaningless + // in this case. + return { nullptr, -1 }; + + // See whether the first node matches. + auto first_result = clobber_group_or_single_def (first); + if (*insn <= *last_def (first_result)->insn ()) + { + int comparison = (*insn >= *first->insn () ? 0 : -1); + return { first_result, comparison }; + } + + // See whether the last node matches. + def_info *last = first->last_def (); + auto last_result = clobber_group_or_single_def (last); + if (*insn >= *first_def (last_result)->insn ()) + { + int comparison = (*insn <= *last->insn () ? 0 : 1); + return { last_result, comparison }; + } + + // Resort to using a splay tree to search for the result. + def_splay_tree tree = need_def_splay_tree (last); + int comparison = lookup_def (tree, insn); + last->set_splay_root (tree.root ()); + return { tree.root (), comparison }; +} + +// Add DEF to the function's list of definitions of DEF->resource (), +// inserting DEF immediately before BEFORE. DEF is not currently in the list. +void +function_info::insert_def_before (def_info *def, def_info *before) +{ + gcc_checking_assert (!def->has_def_links () + && *before->insn () > *def->insn ()); + + def->copy_prev_from (before); + if (def_info *prev = def->prev_def ()) + { + gcc_checking_assert (*prev->insn () < *def->insn ()); + prev->set_next_def (def); + } + else + m_defs[def->regno () + 1] = def; + + def->set_next_def (before); + before->set_prev_def (def); +} + +// Add DEF to the function's list of definitions of DEF->resource (), +// inserting DEF immediately after AFTER. DEF is not currently in the list. +void +function_info::insert_def_after (def_info *def, def_info *after) +{ + gcc_checking_assert (!def->has_def_links () + && *after->insn () < *def->insn ()); + + def->copy_next_from (after); + if (def_info *next = def->next_def ()) + { + gcc_checking_assert (*next->insn () > *def->insn ()); + next->set_prev_def (def); + } + else + m_defs[def->regno () + 1]->set_last_def (def); + + def->set_prev_def (after); + after->set_next_def (def); +} + +// Remove DEF from the function's list of definitions of DEF->resource (). +void +function_info::remove_def_from_list (def_info *def) +{ + def_info *prev = def->prev_def (); + def_info *next = def->next_def (); + + if (next) + next->copy_prev_from (def); + else + m_defs[def->regno () + 1]->set_last_def (prev); + + if (prev) + prev->copy_next_from (def); + else + m_defs[def->regno () + 1] = next; + + def->clear_def_links (); +} + +// Add CLOBBER to GROUP and insert it into the function's list of +// accesses to CLOBBER->resource (). CLOBBER is not currently part +// of an active group and is not currently in the list. +void +function_info::add_clobber (clobber_info *clobber, clobber_group *group) +{ + // Search for either the previous or next clobber in the group. + // The result is less than zero if CLOBBER should come before NEIGHBOR + // or greater than zero if CLOBBER should come after NEIGHBOR. + int comparison = lookup_clobber (group->m_clobber_tree, clobber->insn ()); + gcc_checking_assert (comparison != 0); + clobber_info *neighbor = group->m_clobber_tree.root (); + + // Since HEIGHBOR is now the root of the splay tree, its group needs + // to be up-to-date. + neighbor->update_group (group); + + // If CLOBBER comes before NEIGHBOR, insert CLOBBER to NEIGHBOR's left, + // otherwise insert CLOBBER to NEIGHBOR's right. + clobber_info::splay_tree::insert_child (neighbor, comparison > 0, clobber); + clobber->set_group (group); + + // Insert the clobber into the function-wide list and update the + // bounds of the group. + if (comparison > 0) + { + insert_def_after (clobber, neighbor); + if (neighbor == group->last_clobber ()) + group->set_last_clobber (clobber); + } + else + { + insert_def_before (clobber, neighbor); + if (neighbor == group->first_clobber ()) + group->set_first_clobber (clobber); + } +} + +// Remove CLOBBER from GROUP, given that GROUP contains other clobbers too. +// Also remove CLOBBER from the function's list of accesses to +// CLOBBER->resource (). +void +function_info::remove_clobber (clobber_info *clobber, clobber_group *group) +{ + if (clobber == group->first_clobber ()) + { + auto *new_first = as_a (clobber->next_def ()); + group->set_first_clobber (new_first); + new_first->update_group (group); + } + else if (clobber == group->last_clobber ()) + { + auto *new_last = as_a (clobber->prev_def ()); + group->set_last_clobber (new_last); + new_last->update_group (group); + } + + clobber_info *replacement = clobber_info::splay_tree::remove_node (clobber); + if (clobber == group->m_clobber_tree.root ()) + { + group->m_clobber_tree = replacement; + replacement->update_group (group); + } + clobber->set_group (nullptr); + + remove_def_from_list (clobber); +} + +// Add CLOBBER immediately before the first clobber in GROUP, given that +// CLOBBER is not currently part of any group. +void +function_info::prepend_clobber_to_group (clobber_info *clobber, + clobber_group *group) +{ + clobber_info *next = group->first_clobber (); + clobber_info::splay_tree::insert_child (next, 0, clobber); + group->set_first_clobber (clobber); + clobber->set_group (group); +} + +// Add CLOBBER immediately after the last clobber in GROUP, given that +// CLOBBER is not currently part of any group. +void +function_info::append_clobber_to_group (clobber_info *clobber, + clobber_group *group) +{ + clobber_info *prev = group->last_clobber (); + clobber_info::splay_tree::insert_child (prev, 1, clobber); + group->set_last_clobber (clobber); + clobber->set_group (group); +} + +// Put CLOBBER1 and CLOBBER2 into the same clobber_group, given that +// CLOBBER1 occurs immediately before CLOBBER2 and that the two clobbers +// are not currently in the same group. LAST is the last definition of +// the associated resource, and is where any splay tree is stored. +void +function_info::merge_clobber_groups (clobber_info *clobber1, + clobber_info *clobber2, + def_info *last) +{ + if (clobber1->is_in_group () && clobber2->is_in_group ()) + { + clobber_group *group1 = clobber1->group (); + clobber_group *group2 = clobber2->group (); + gcc_checking_assert (clobber1 == group1->last_clobber () + && clobber2 == group2->first_clobber ()); + + if (def_splay_tree tree = last->splay_root ()) + { + // Remove GROUP2 from the splay tree. + int comparison = lookup_def (tree, clobber2->insn ()); + gcc_checking_assert (comparison == 0); + tree.remove_root (); + last->set_splay_root (tree.root ()); + } + + // Splice the trees together. + group1->m_clobber_tree.splice_next_tree (group2->m_clobber_tree); + + // Bring the two extremes of GROUP2 under GROUP1. Any other + // clobbers in the group are updated lazily on demand. + clobber2->set_group (group1); + group2->last_clobber ()->set_group (group1); + group1->set_last_clobber (group2->last_clobber ()); + + // Record that GROUP2 is no more. + group2->set_first_clobber (nullptr); + group2->set_last_clobber (nullptr); + group2->m_clobber_tree = nullptr; + } + else + { + // In this case there can be no active splay tree. + gcc_assert (!last->splay_root ()); + if (clobber2->is_in_group ()) + prepend_clobber_to_group (clobber1, clobber2->group ()); + else + append_clobber_to_group (clobber2, need_clobber_group (clobber1)); + } +} + +// GROUP spans INSN, and INSN now sets the resource that GROUP clobbers. +// Split GROUP around INSN and return the clobber that comes immediately +// before INSN. +clobber_info * +function_info::split_clobber_group (clobber_group *group, insn_info *insn) +{ + // Search for either the previous or next clobber in the group. + // The result is less than zero if CLOBBER should come before NEIGHBOR + // or greater than zero if CLOBBER should come after NEIGHBOR. + int comparison = lookup_clobber (group->m_clobber_tree, insn); + gcc_checking_assert (comparison != 0); + clobber_info *neighbor = group->m_clobber_tree.root (); + + clobber_tree tree1, tree2; + clobber_info *prev; + clobber_info *next; + if (comparison > 0) + { + // NEIGHBOR is the last clobber in what will become the first group. + tree1 = neighbor; + tree2 = tree1.split_after_root (); + prev = neighbor; + next = as_a (prev->next_def ()); + } + else + { + // NEIGHBOR is the first clobber in what will become the second group. + tree2 = neighbor; + tree1 = tree2.split_before_root (); + next = neighbor; + prev = as_a (next->prev_def ()); + } + + // Use GROUP to hold PREV and earlier clobbers. Create a new group for + // NEXT onwards. + clobber_info *last_clobber = group->last_clobber (); + clobber_group *group1 = group; + clobber_group *group2 = allocate (next); + + // Finish setting up GROUP1, making sure that the roots and extremities + // have a correct group pointer. Leave the rest to be updated lazily. + group1->set_last_clobber (prev); + tree1->set_group (group1); + prev->set_group (group1); + + // Finish setting up GROUP2, with the same approach as for GROUP1. + group2->set_first_clobber (next); + group2->set_last_clobber (last_clobber); + next->set_group (group2); + tree2->set_group (group2); + last_clobber->set_group (group2); + + return prev; +} + +// Add DEF to the end of the function's list of definitions of +// DEF->resource (). There is known to be no associated splay tree yet. +void +function_info::append_def (def_info *def) +{ + gcc_checking_assert (!def->has_def_links ()); + def_info **head = &m_defs[def->regno () + 1]; + def_info *first = *head; + if (!first) + { + // This is the only definition of the resource. + def->set_last_def (def); + *head = def; + return; + } + + def_info *prev = first->last_def (); + gcc_checking_assert (!prev->splay_root ()); + + // Maintain the invariant that two clobbers must not appear in + // neighboring nodes of the splay tree. + auto *clobber = dyn_cast (def); + auto *prev_clobber = dyn_cast (prev); + if (clobber && prev_clobber) + append_clobber_to_group (clobber, need_clobber_group (prev_clobber)); + + prev->set_next_def (def); + def->set_prev_def (prev); + first->set_last_def (def); +} + +// Add DEF to the function's list of definitions of DEF->resource (). +// Also insert it into the associated splay tree, if there is one. +// DEF is not currently part of the list and is not in the splay tree. +void +function_info::add_def (def_info *def) +{ + gcc_checking_assert (!def->has_def_links () + && !def->m_is_temp + && !def->m_has_been_superceded); + def_info **head = &m_defs[def->regno () + 1]; + def_info *first = *head; + if (!first) + { + // This is the only definition of the resource. + def->set_last_def (def); + *head = def; + return; + } + + def_info *last = first->last_def (); + insn_info *insn = def->insn (); + + int comparison; + def_node *root = nullptr; + def_info *prev = nullptr; + def_info *next = nullptr; + if (*insn > *last->insn ()) + { + // This definition comes after all other definitions. + comparison = 1; + if (def_splay_tree tree = last->splay_root ()) + { + tree.splay_max_node (); + root = tree.root (); + last->set_splay_root (root); + } + prev = last; + } + else if (*insn < *first->insn ()) + { + // This definition comes before all other definitions. + comparison = -1; + if (def_splay_tree tree = last->splay_root ()) + { + tree.splay_min_node (); + root = tree.root (); + last->set_splay_root (root); + } + next = first; + } + else + { + // Search the splay tree for an insertion point. + def_splay_tree tree = need_def_splay_tree (last); + comparison = lookup_def (tree, insn); + root = tree.root (); + last->set_splay_root (root); + + // Deal with cases in which we found an overlapping live range. + if (comparison == 0) + { + auto *group = as_a (tree.root ()); + if (auto *clobber = dyn_cast (def)) + { + add_clobber (clobber, group); + return; + } + prev = split_clobber_group (group, insn); + next = prev->next_def (); + } + // COMPARISON is < 0 if DEF comes before ROOT or > 0 if DEF comes + // after ROOT. + else if (comparison < 0) + { + next = first_def (root); + prev = next->prev_def (); + } + else + { + prev = last_def (root); + next = prev->next_def (); + } + } + + // See if we should merge CLOBBER with a neighboring clobber. + auto *clobber = dyn_cast (def); + auto *prev_clobber = safe_dyn_cast (prev); + auto *next_clobber = safe_dyn_cast (next); + // We shouldn't have consecutive clobber_groups. + gcc_checking_assert (!(clobber && prev_clobber && next_clobber)); + if (clobber && prev_clobber) + append_clobber_to_group (clobber, need_clobber_group (prev_clobber)); + else if (clobber && next_clobber) + prepend_clobber_to_group (clobber, need_clobber_group (next_clobber)); + else if (root) + { + // If DEF comes before ROOT, insert DEF to ROOT's left, + // otherwise insert DEF to ROOT's right. + def_node *node = need_def_node (def); + def_splay_tree::insert_child (root, comparison >= 0, node); + } + if (prev) + insert_def_after (def, prev); + else + insert_def_before (def, next); +} + +// Remove DEF from the function's list of definitions of DEF->resource (). +// Also remove DEF from the associated splay tree, if there is one. +void +function_info::remove_def (def_info *def) +{ + def_info **head = &m_defs[def->regno () + 1]; + def_info *first = *head; + gcc_checking_assert (first); + if (first->is_last_def ()) + { + // DEF is the only definition of the resource. + gcc_checking_assert (first == def); + *head = nullptr; + def->clear_def_links (); + return; + } + + // If CLOBBER belongs to a clobber_group that contains other clobbers + // too, then we need to update the clobber_group and the list, but any + // splay tree that contains the clobber_group is unaffected. + if (auto *clobber = dyn_cast (def)) + if (clobber->is_in_group ()) + { + clobber_group *group = clobber->group (); + if (group->first_clobber () != group->last_clobber ()) + { + remove_clobber (clobber, group); + return; + } + } + + // If we've created a splay tree for this resource, remove the entry + // for DEF. + def_info *last = first->last_def (); + if (def_splay_tree tree = last->splay_root ()) + { + int comparison = lookup_def (tree, def->insn ()); + gcc_checking_assert (comparison == 0); + tree.remove_root (); + last->set_splay_root (tree.root ()); + } + + // If the definition came between two clobbers, merge them into a single + // group. + auto *prev_clobber = safe_dyn_cast (def->prev_def ()); + auto *next_clobber = safe_dyn_cast (def->next_def ()); + if (prev_clobber && next_clobber) + merge_clobber_groups (prev_clobber, next_clobber, last); + + remove_def_from_list (def); +} + +// Require DEF to have a splay tree that contains all non-phi uses. +void +function_info::need_use_splay_tree (set_info *def) +{ + if (!def->m_use_tree) + for (use_info *use : def->all_insn_uses ()) + { + auto *use_node = allocate> (use); + def->m_use_tree.insert_max_node (use_node); + } +} + +// Compare two instructions by their position in a use splay tree. Return >0 +// if INSN1 comes after INSN2, <0 if INSN1 comes before INSN2, or 0 if they are +// the same instruction. +static inline int +compare_use_insns (insn_info *insn1, insn_info *insn2) +{ + // Debug instructions go after nondebug instructions. + int diff = insn1->is_debug_insn () - insn2->is_debug_insn (); + if (diff != 0) + return diff; + return insn1->compare_with (insn2); +} + +// Search TREE for a use in INSN. If such a use exists, install it as +// the root of TREE and return 0. Otherwise arbitrarily choose between: +// +// (1) Installing the closest preceding use as the root and returning 1. +// (2) Installing the closest following use as the root and returning -1. +int +rtl_ssa::lookup_use (splay_tree &tree, insn_info *insn) +{ + auto compare = [&](splay_tree_node *node) + { + return compare_use_insns (insn, node->value ()->insn ()); + }; + return tree.lookup (compare); +} + +// Add USE to USE->def ()'s list of uses. inserting USE immediately before +// BEFORE. USE is not currently in the list. +// +// This routine should not be used for inserting phi uses. +void +function_info::insert_use_before (use_info *use, use_info *before) +{ + gcc_checking_assert (!use->has_use_links () && use->is_in_any_insn ()); + + set_info *def = use->def (); + + use->copy_prev_from (before); + use->set_next_use (before); + + if (use_info *prev = use->prev_use ()) + prev->set_next_use (use); + else + use->def ()->set_first_use (use); + + before->set_prev_use (use); + if (use->is_in_nondebug_insn () && before->is_in_debug_insn_or_phi ()) + def->last_use ()->set_last_nondebug_insn_use (use); + + gcc_checking_assert (use->check_integrity () && before->check_integrity ()); +} + +// Add USE to USE->def ()'s list of uses. inserting USE immediately after +// AFTER. USE is not currently in the list. +// +// This routine should not be used for inserting phi uses. +void +function_info::insert_use_after (use_info *use, use_info *after) +{ + set_info *def = use->def (); + gcc_checking_assert (after->is_in_any_insn () + && !use->has_use_links () + && use->is_in_any_insn ()); + + use->set_prev_use (after); + use->copy_next_from (after); + + after->set_next_use (use); + + if (use_info *next = use->next_use ()) + { + // The last node doesn't change, but we might need to update its + // last_nondebug_insn_use record. + if (use->is_in_nondebug_insn () && next->is_in_debug_insn_or_phi ()) + def->last_use ()->set_last_nondebug_insn_use (use); + next->set_prev_use (use); + } + else + { + // USE is now the last node. + if (use->is_in_nondebug_insn ()) + use->set_last_nondebug_insn_use (use); + def->first_use ()->set_last_use (use); + } + + gcc_checking_assert (use->check_integrity () && after->check_integrity ()); +} + +// If USE has a known definition, add USE to that definition's list of uses. +// Also update the associated splay tree, if any. +void +function_info::add_use (use_info *use) +{ + gcc_checking_assert (!use->has_use_links () + && !use->m_is_temp + && !use->m_has_been_superceded); + + set_info *def = use->def (); + if (!def) + return; + + use_info *first = def->first_use (); + if (!first) + { + // This is the only use of the definition. + use->set_last_use (use); + if (use->is_in_nondebug_insn ()) + use->set_last_nondebug_insn_use (use); + + def->set_first_use (use); + + gcc_checking_assert (use->check_integrity ()); + return; + } + + if (use->is_in_phi ()) + { + // Add USE at the end of the list, as the new first phi. + use_info *last = first->last_use (); + + use->set_prev_use (last); + use->copy_next_from (last); + + last->set_next_use (use); + first->set_last_use (use); + + gcc_checking_assert (use->check_integrity ()); + return; + } + + // If there is currently no splay tree for this definition, see if can + // get away with a pure list-based update. + insn_info *insn = use->insn (); + auto quick_path = [&]() + { + // Check if USE should come before all current uses. + if (first->is_in_phi () || compare_use_insns (insn, first->insn ()) < 0) + { + insert_use_before (use, first); + return true; + } + + // Check if USE should come after all current uses in the same + // subsequence (i.e. the list of nondebug insn uses or the list + // of debug insn uses). + use_info *last = first->last_use (); + if (use->is_in_debug_insn ()) + { + if (last->is_in_phi ()) + return false; + } + else + last = last->last_nondebug_insn_use (); + + if (compare_use_insns (insn, last->insn ()) > 0) + { + insert_use_after (use, last); + return true; + } + + return false; + }; + if (!def->m_use_tree && quick_path ()) + return; + + // Search the splay tree for an insertion point. COMPARISON is less + // than zero if USE should come before NEIGHBOR, or greater than zero + // if USE should come after NEIGHBOR. + need_use_splay_tree (def); + int comparison = lookup_use (def->m_use_tree, insn); + gcc_checking_assert (comparison != 0); + splay_tree_node *neighbor = def->m_use_tree.root (); + + // If USE comes before NEIGHBOR, insert USE to NEIGHBOR's left, + // otherwise insert USE to NEIGHBOR's right. + auto *use_node = allocate> (use); + def->m_use_tree.insert_child (neighbor, comparison > 0, use_node); + if (comparison > 0) + insert_use_after (use, neighbor->value ()); + else + insert_use_before (use, neighbor->value ()); +} + +// If USE has a known definition, remove USE from that definition's list +// of uses. Also remove if it from the associated splay tree, if any. +void +function_info::remove_use (use_info *use) +{ + set_info *def = use->def (); + if (!def) + return; + + // Remove USE from the splay tree. + if (def->m_use_tree && use->is_in_any_insn ()) + { + int comparison = lookup_use (def->m_use_tree, use->insn ()); + gcc_checking_assert (comparison == 0); + def->m_use_tree.remove_root (); + } + + use_info *prev = use->prev_use (); + use_info *next = use->next_use (); + + use_info *first = def->first_use (); + use_info *last = first->last_use (); + if (last->last_nondebug_insn_use () == use) + last->set_last_nondebug_insn_use (prev); + + if (next) + next->copy_prev_from (use); + else + first->set_last_use (prev); + + if (prev) + prev->copy_next_from (use); + else + def->set_first_use (next); + + use->clear_use_links (); + gcc_checking_assert ((!prev || prev->check_integrity ()) + && (!next || next->check_integrity ())); +} + +// Allocate a temporary clobber_info for register REGNO in insn INSN, +// including it in the region of the obstack governed by WATERMARK. +// Return a new def_array that contains OLD_DEFS and the new clobber. +// +// OLD_DEFS is known not to define REGNO. +def_array +function_info::insert_temp_clobber (obstack_watermark &watermark, + insn_info *insn, unsigned int regno, + def_array old_defs) +{ + gcc_checking_assert (watermark == &m_temp_obstack); + auto *clobber = allocate_temp (insn, regno); + clobber->m_is_temp = true; + return insert_access (watermark, clobber, old_defs); +} + +// A subroutine of make_uses_available. Try to make USE's definition +// available at the head of BB. On success: +// +// - If the use would have the same def () as USE, return USE. +// +// - If BB already has a degenerate phi for the same definition, +// return a temporary use of that phi. +// +// - Otherwise, the use would need a new degenerate phi. Allocate a +// temporary phi and return a temporary use of it. +// +// Return null on failure. +use_info * +function_info::make_use_available (use_info *use, bb_info *bb) +{ + set_info *def = use->def (); + if (!def) + return use; + + if (is_single_dominating_def (def)) + return use; + + // FIXME: Deliberately limited for fwprop compatibility testing. + basic_block cfg_bb = bb->cfg_bb (); + bb_info *use_bb = use->bb (); + if (single_pred_p (cfg_bb) + && single_pred (cfg_bb) == use_bb->cfg_bb () + && remains_available_on_exit (def, use_bb)) + { + if (def->ebb () == bb->ebb ()) + return use; + + resource_info resource = use->resource (); + set_info *ultimate_def = look_through_degenerate_phi (def); + + // See if there is already a (degenerate) phi for DEF. + insn_info *phi_insn = bb->ebb ()->phi_insn (); + phi_info *phi; + def_lookup dl = find_def (resource, phi_insn); + if (set_info *set = dl.matching_set ()) + { + // There is an existing phi. + phi = as_a (set); + gcc_checking_assert (phi->input_value (0) == ultimate_def); + } + else + { + // Create a temporary placeholder phi. This will become + // permanent if the change is later committed. + phi = allocate_temp (phi_insn, resource, 0); + auto *input = allocate (phi, resource, ultimate_def); + input->m_is_temp = true; + phi->m_is_temp = true; + phi->make_degenerate (input); + if (def_info *prev = dl.prev_def ()) + phi->set_prev_def (prev); + if (def_info *next = dl.next_def ()) + phi->set_next_def (next); + } + + // Create a temporary use of the phi at the head of the first + // block, since we know for sure that it's available there. + insn_info *use_insn = bb->ebb ()->first_bb ()->head_insn (); + auto *new_use = allocate_temp (use_insn, resource, phi); + new_use->m_is_temp = true; + return new_use; + } + return nullptr; +} + +// See the comment above the declaration. +use_array +function_info::make_uses_available (obstack_watermark &watermark, + use_array uses, bb_info *bb) +{ + unsigned int num_uses = uses.size (); + if (num_uses == 0) + return uses; + + auto **new_uses = XOBNEWVEC (watermark, access_info *, num_uses); + for (unsigned int i = 0; i < num_uses; ++i) + { + use_info *use = make_use_available (uses[i], bb); + if (!use) + return use_array (access_array::invalid ()); + new_uses[i] = use; + } + return use_array (new_uses, num_uses); +} + +// Return true if ACCESS1 can represent ACCESS2 and if ACCESS2 can +// represent ACCESS1. +static bool +can_merge_accesses (access_info *access1, access_info *access2) +{ + if (access1 == access2) + return true; + + auto *use1 = dyn_cast (access1); + auto *use2 = dyn_cast (access2); + return use1 && use2 && use1->def () == use2->def (); +} + +// See the comment above the declaration. +access_array +rtl_ssa::merge_access_arrays_base (obstack_watermark &watermark, + access_array accesses1, + access_array accesses2) +{ + if (accesses1.empty ()) + return accesses2; + if (accesses2.empty ()) + return accesses1; + + auto i1 = accesses1.begin (); + auto end1 = accesses1.end (); + auto i2 = accesses2.begin (); + auto end2 = accesses2.end (); + + access_array_builder builder (watermark); + builder.reserve (accesses1.size () + accesses2.size ()); + + while (i1 != end1 && i2 != end2) + { + access_info *access1 = *i1; + access_info *access2 = *i2; + + unsigned int regno1 = access1->regno (); + unsigned int regno2 = access2->regno (); + if (regno1 == regno2) + { + if (!can_merge_accesses (access1, access2)) + return access_array::invalid (); + + builder.quick_push (access1); + ++i1; + ++i2; + } + else if (regno1 < regno2) + { + builder.quick_push (access1); + ++i1; + } + else + { + builder.quick_push (access2); + ++i2; + } + } + for (; i1 != end1; ++i1) + builder.quick_push (*i1); + for (; i2 != end2; ++i2) + builder.quick_push (*i2); + + return builder.finish (); +} + +// See the comment above the declaration. +access_array +rtl_ssa::insert_access_base (obstack_watermark &watermark, + access_info *access1, access_array accesses2) +{ + access_array_builder builder (watermark); + builder.reserve (1 + accesses2.size ()); + + unsigned int regno1 = access1->regno (); + auto i2 = accesses2.begin (); + auto end2 = accesses2.end (); + while (i2 != end2) + { + access_info *access2 = *i2; + + unsigned int regno2 = access2->regno (); + if (regno1 == regno2) + { + if (!can_merge_accesses (access1, access2)) + return access_array::invalid (); + + builder.quick_push (access1); + access1 = nullptr; + ++i2; + break; + } + else if (regno1 < regno2) + { + builder.quick_push (access1); + access1 = nullptr; + break; + } + else + { + builder.quick_push (access2); + ++i2; + } + } + if (access1) + builder.quick_push (access1); + for (; i2 != end2; ++i2) + builder.quick_push (*i2); + + return builder.finish (); +} + +// See the comment above the declaration. +access_array +rtl_ssa::remove_note_accesses_base (obstack_watermark &watermark, + access_array accesses) +{ + for (access_info *access : accesses) + if (access->only_occurs_in_notes ()) + { + access_array_builder builder (watermark); + builder.reserve (accesses.size ()); + for (access_info *access2 : accesses) + if (!access2->only_occurs_in_notes ()) + builder.quick_push (access2); + return builder.finish (); + } + return accesses; +} + +// Print RESOURCE to PP. +void +rtl_ssa::pp_resource (pretty_printer *pp, resource_info resource) +{ + resource.print (pp); +} + +// Print ACCESS to PP. FLAGS is a bitmask of PP_ACCESS_* flags. +void +rtl_ssa::pp_access (pretty_printer *pp, const access_info *access, + unsigned int flags) +{ + if (!access) + pp_string (pp, ""); + else if (auto *phi = dyn_cast (access)) + phi->print (pp, flags); + else if (auto *set = dyn_cast (access)) + set->print (pp, flags); + else if (auto *clobber = dyn_cast (access)) + clobber->print (pp, flags); + else if (auto *use = dyn_cast (access)) + use->print (pp, flags); + else + pp_string (pp, "??? Unknown access"); +} + +// Print ACCESSES to PP. FLAGS is a bitmask of PP_ACCESS_* flags. +void +rtl_ssa::pp_accesses (pretty_printer *pp, access_array accesses, + unsigned int flags) +{ + if (accesses.empty ()) + pp_string (pp, "none"); + else + { + bool is_first = true; + for (access_info *access : accesses) + { + if (is_first) + is_first = false; + else + pp_newline_and_indent (pp, 0); + pp_access (pp, access, flags); + } + } +} + +// Print NODE to PP. +void +rtl_ssa::pp_def_node (pretty_printer *pp, const def_node *node) +{ + if (!node) + pp_string (pp, ""); + else if (auto *group = dyn_cast (node)) + group->print (pp); + else if (auto *set = dyn_cast (node)) + set->print (pp); + else + pp_string (pp, "??? Unknown def node"); +} + +// Print MUX to PP. +void +rtl_ssa::pp_def_mux (pretty_printer *pp, def_mux mux) +{ + if (auto *node = mux.dyn_cast ()) + pp_def_node (pp, node); + else + pp_access (pp, mux.as_a ()); +} + +// Print DL to PP. +void +rtl_ssa::pp_def_lookup (pretty_printer *pp, def_lookup dl) +{ + pp_string (pp, "comparison result of "); + pp_decimal_int (pp, dl.comparison); + pp_string (pp, " for "); + pp_newline_and_indent (pp, 0); + pp_def_mux (pp, dl.mux); +} + +// Dump RESOURCE to FILE. +void +dump (FILE *file, resource_info resource) +{ + dump_using (file, pp_resource, resource); +} + +// Dump ACCESS to FILE. FLAGS is a bitmask of PP_ACCESS_* flags. +void +dump (FILE *file, const access_info *access, unsigned int flags) +{ + dump_using (file, pp_access, access, flags); +} + +// Dump ACCESSES to FILE. FLAGS is a bitmask of PP_ACCESS_* flags. +void +dump (FILE *file, access_array accesses, unsigned int flags) +{ + dump_using (file, pp_accesses, accesses, flags); +} + +// Print NODE to FILE. +void +dump (FILE *file, const def_node *node) +{ + dump_using (file, pp_def_node, node); +} + +// Print MUX to FILE. +void +dump (FILE *file, def_mux mux) +{ + dump_using (file, pp_def_mux, mux); +} + +// Print RESULT to FILE. +void +dump (FILE *file, def_lookup result) +{ + dump_using (file, pp_def_lookup, result); +} + +// Debug interfaces to the dump routines above. +void debug (const resource_info &x) { dump (stderr, x); } +void debug (const access_info *x) { dump (stderr, x); } +void debug (const access_array &x) { dump (stderr, x); } +void debug (const def_node *x) { dump (stderr, x); } +void debug (const def_mux &x) { dump (stderr, x); } +void debug (const def_lookup &x) { dump (stderr, x); } diff --git a/gcc/rtl-ssa/accesses.h b/gcc/rtl-ssa/accesses.h new file mode 100644 index 0000000..fdb4a64 --- /dev/null +++ b/gcc/rtl-ssa/accesses.h @@ -0,0 +1,1032 @@ +// Access-related classes for RTL SSA -*- C++ -*- +// Copyright (C) 2020 Free Software Foundation, Inc. +// +// This file is part of GCC. +// +// GCC is free software; you can redistribute it and/or modify it under +// the terms of the GNU General Public License as published by the Free +// Software Foundation; either version 3, or (at your option) any later +// version. +// +// GCC is distributed in the hope that it will be useful, but WITHOUT ANY +// WARRANTY; without even the implied warranty of MERCHANTABILITY or +// FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License +// for more details. +// +// You should have received a copy of the GNU General Public License +// along with GCC; see the file COPYING3. If not see +// . + +namespace rtl_ssa { + +// Forward declarations. +class bb_info; +class clobber_group; +class def_node; +class ebb_info; +class insn_info; +class phi_info; +class set_info; + +// Used as a boolean argunent to certain routines. +enum class ignore_clobbers { NO, YES }; + +// Represents something that the SSA form tracks: either a register +// or memory. +class resource_info +{ +public: + // Return true if this resource represents memory. + bool is_mem () const { return regno == MEM_REGNO; } + + // Return true if this resource represents a register. + bool is_reg () const { return regno != MEM_REGNO; } + + // Print the name of the resource to PP. + void print_identifier (pretty_printer *pp) const; + + // Possibly print additional information about the resource to PP. + void print_context (pretty_printer *pp) const; + + // A combination of print_identifier and print_context. + void print (pretty_printer *pp) const; + + // The mode with which the resource is being defined or used. This is + // always BLKmode for memory. It can also be BLKmode for registers if + // we don't yet know the real mode, or if the mode is not relevant for + // some reason. + machine_mode mode; + + // The pseudo register or single hard register that the resource represents, + // or MEM_REGNO for memory. + unsigned int regno; +}; + +// For simplicity, we treat memory as a single unified entity. +const resource_info memory = { E_BLKmode, MEM_REGNO }; + +// Flags used when printing access_infos. +// +// Print the location at which the access occurs. This is redundant +// when the access is being printed as part of the instruction or phi node +// that contains the access. +const unsigned int PP_ACCESS_INCLUDE_LOCATION = 1U << 0; +// +// Print links to other accesses: the definition that defines a use, +// the uses of a definition, and the inputs of a phi node. +const unsigned int PP_ACCESS_INCLUDE_LINKS = 1U << 1; +// +// Print additional properties about the access. +const unsigned int PP_ACCESS_INCLUDE_PROPERTIES = 1U << 2; +// +// The usual flags when printing an access in isolation. +const unsigned int PP_ACCESS_DEFAULT = (PP_ACCESS_INCLUDE_LOCATION + | PP_ACCESS_INCLUDE_LINKS + | PP_ACCESS_INCLUDE_PROPERTIES); +// +// The usual flags when printing a def_info from its defining instruction. +const unsigned int PP_ACCESS_SETTER = (PP_ACCESS_INCLUDE_LINKS + | PP_ACCESS_INCLUDE_PROPERTIES); +// +// The usual flags when printing a use_info from its user. +const unsigned int PP_ACCESS_USER = PP_ACCESS_INCLUDE_PROPERTIES; + +// The various ways of accessing a resource. The two range checks that +// we need to perform are [SET, PHI] (for set_info) and [SET, CLOBBER] +// (for def_info), so the ordering tries to make those tests as +// efficient as possible. +enum class access_kind : uint8_t +{ + // Set the resource to a useful value. + SET, + + // A form of SET that collects the possible incoming values of the + // resource using a phi node; the resource does not actually change value. + PHI, + + // Set the resource to a value that is both unknown and not useful. + CLOBBER, + + // Use the current value of the resource. + USE +}; + +// A base class that represents an access to a resource. +class access_info +{ + // Size: 1 LP64 word + friend class function_info; + +public: + // Return the resource that is being accessed. + resource_info resource () const { return { m_mode, m_regno }; } + + // Return true if the access is to memory. + bool is_mem () const { return m_regno == MEM_REGNO; } + + // Return true if the access is to a register. + bool is_reg () const { return m_regno != MEM_REGNO; } + + // If the access is to a register, return the register number, + // otherwise return MEM_REGNO. + unsigned int regno () const { return m_regno; } + + // For sets, return the mode of the value to which the resource is being set. + // For uses, return the mode in which the resource is being used (which for + // hard registers might be different from the mode in which the resource + // was set). + // + // When accessing memory, the mode is always BLKmode. When accessing + // pseudo registers, the mode is always the mode of the pseudo register + // (and so doesn't, for example, take subregs into account). + machine_mode mode () const { return m_mode; } + + // Return the kind of access that this is. + access_kind kind () const { return m_kind; } + + // Return true if the access occurs in a phi node or an "artificial" + // instruction (see insn_info), false if it occurs in a real instruction. + bool is_artificial () const { return m_is_artificial; } + + // Return the opposite of is_artificial. + bool is_real () const { return !m_is_artificial; } + + // Return true if this access is a set_info whose result is used by at least + // one nondebug instruction. + bool is_set_with_nondebug_insn_uses () const; + + // Return true if the access describes a set_info and if the value + // is defined by an RTX_AUTOINC rtx. + bool is_pre_post_modify () const { return m_is_pre_post_modify; } + + // Return true if the access is a clobber_info that describes the effect + // of a called function. This kind of clobber is added for -fipa-ra + // functions that clobber only a strict subset of the normal ABI set. + bool is_call_clobber () const { return m_is_call_clobber; } + + // Return true if the access is a use_info that simply marks a point in + // the live range of a set_info at which the value is live out from + // the containing EBB. + bool is_live_out_use () const { return m_is_live_out_use; } + + // Return true if the access is a use_info for an instruction and if + // at least some of the uses occur within a MEM address. + // + // There shouldn't be a need to check whether *all* uses occur within + // a MEM address, since in principle: + // + // A: (set (reg:SI R1) (mem:SI (post_inc:SI (reg:SI R2)))) + // + // should be semantically equivalent to: + // + // B: (parallel [(set (reg:SI R1) (mem:SI (reg:SI R2))) + // (set (reg:SI R2) (plus:SI (reg:SI R2) (const_int 4)))]) + // + // even though R2 occurs only in MEMs for A but occurs outside MEMs for B. + bool includes_address_uses () const { return m_includes_address_uses; } + + // Return true if the access occurs in an instruction and if at least + // some accesses to resource () occur in a read-modify-write context. + // This is equivalent to the DF_REF_READ_WRITE flag. + bool includes_read_writes () const { return m_includes_read_writes; } + + // Return true if the access occurs in an instruction and if at least + // some accesses to resource () occur in a subreg context. + bool includes_subregs () const { return m_includes_subregs; } + + // Return true if the access occurs in an instruction and if at least + // some accesses to resource () occur in a multi-register REG. + // This implies that resource () is a hard register. + bool includes_multiregs () const { return m_includes_multiregs; } + + // Return true if the access occurs in a real nondebug instruction + // and if all accesses to resource () occur in notes, rather than + // in the main instruction pattern. + bool only_occurs_in_notes () const { return m_only_occurs_in_notes; } + +protected: + access_info (resource_info, access_kind); + + void print_prefix_flags (pretty_printer *) const; + void print_properties_on_new_lines (pretty_printer *) const; + +private: + void set_mode (machine_mode mode) { m_mode = mode; } + + // The values returned by the accessors above. + unsigned int m_regno; + access_kind m_kind : 8; + +protected: + // The value returned by the accessors above. + unsigned int m_is_artificial : 1; + unsigned int m_is_set_with_nondebug_insn_uses : 1; + unsigned int m_is_pre_post_modify : 1; + unsigned int m_is_call_clobber : 1; + unsigned int m_is_live_out_use : 1; + unsigned int m_includes_address_uses : 1; + unsigned int m_includes_read_writes : 1; + unsigned int m_includes_subregs : 1; + unsigned int m_includes_multiregs : 1; + unsigned int m_only_occurs_in_notes : 1; + + // True if this access is a use_insn that occurs in a nondebug instruction, + // and if there are no following uses by nondebug instructions. The next use + // is null, a use_info for a debug instruction, or a use_info for a phi node. + // + // Providing this helps to optimize use_info::next_nondebug_insn_use. + unsigned int m_is_last_nondebug_insn_use : 1; + + // True if this access is a use_info for a debug instruction or + // a phi node. + unsigned int m_is_in_debug_insn_or_phi : 1; + +private: + // Used as a flag during various update routines; has no long-lasting + // meaning. + unsigned int m_has_been_superceded : 1; + + // Indicates that this access has been allocated on the function_info's + // temporary obstack and so is not (yet) part of the proper SSA form. + unsigned int m_is_temp : 1; + + // Bits for future expansion. + unsigned int m_spare : 2; + + // The value returned by the accessor above. + machine_mode m_mode : 8; +}; + +// A contiguous array of access_info pointers. Used to represent a +// (mostly small) number of definitions and/or uses. +using access_array = array_slice; + +// A class for building an access_array on an obstack. It automatically +// frees any in-progress array if the build attempt fails before finish () +// has been called. +class access_array_builder : public obstack_watermark +{ +public: + using obstack_watermark::obstack_watermark; + + // Make sure that the array has enough for NUM_ACCESSES accesses. + void reserve (unsigned int num_accesses); + + // Add ACCESS to the end of the array that we're building, given that + // reserve () has already made room. + void quick_push (access_info *access); + + // Finish and return the new array. The array survives the destruction + // of the builder. + array_slice finish (); +}; + +// An access_info that represents the use of a resource in either a phi node +// or an instruction. It records which set_info (if any) provides the +// resource's value. +class use_info : public access_info +{ + // Overall size: 5 LP64 words. + friend class set_info; + friend class function_info; + +public: + // Return true if the access occurs in an instruction rather than a phi node. + // The instruction might be a debug instruction or a nondebug instruction. + bool is_in_any_insn () const { return m_insn_or_phi.is_first (); } + + // Return true if the access occurs in a nondebug instruction, + // false if it occurs in a debug instruction or a phi node. + bool is_in_nondebug_insn () const { return !m_is_in_debug_insn_or_phi; } + + // Return true if the instruction occurs in a debug instruction. + bool is_in_debug_insn () const; + + // Return true if the access occurs in a phi node rather than in an + // instruction. + bool is_in_phi () const { return m_insn_or_phi.is_second (); } + + // Return true if the access occurs in a debug instruction or a phi node, + // false if it occurs in a nondebug instruction. + bool is_in_debug_insn_or_phi () const { return m_is_in_debug_insn_or_phi; } + + // Return the instruction that uses the resource. Only valid is + // is_in_any_insn (). + insn_info *insn () const { return m_insn_or_phi.known_first (); } + + // Return the phi node that uses the resource. Only valid if is_in_phi (). + phi_info *phi () const { return m_insn_or_phi.known_second (); } + + // Return the basic block that contains the access. + bb_info *bb () const; + + // Return the extended basic block that contains the access. + ebb_info *ebb () const; + + // Return the set_info whose result the access uses, or null if the + // value of the resource is completely undefined. + // + // The value is undefined if the use is completely upwards exposed + // (i.e. has no preceding definition) or if the preceding definition + // is a clobber rather than a set. + // + // The mode of the definition can be different from the mode of the use; + // for example, a hard register might be set in DImode and used in SImode. + set_info *def () const { return m_def; } + + // Return the previous and next uses of the definition. See set_info + // for details about the ordering. + // + // These routines are only meaningful when def () is nonnull. + use_info *prev_use () const; + use_info *next_use () const; + + // Return the next use by a nondebug instruction, or null if none. + // + // This is only valid if is_in_nondebug_insn (). It is equivalent to, + // but more efficient than: + // + // next_use () && next_use ()->is_in_nondebug_insn () + // ? next_use () : nullptr + use_info *next_nondebug_insn_use () const; + + // Return the next use by an instruction, or null if none. The use might + // be by a debug instruction or a nondebug instruction. + // + // This is only valid if is_in_any_insn (). It is equivalent to: + // + // next_use () && next_use ()->is_in_any_insn () ? next_use () : nullptr + use_info *next_any_insn_use () const; + + // Return the previous use by a phi node in the list, or null if none. + // + // This is only valid if is_in_phi (). It is equivalent to: + // + // prev_use () && prev_use ()->is_in_phi () ? prev_use () : nullptr + use_info *prev_phi_use () const; + + // Return true if this is the first use of the definition. See set_info + // for details about the ordering. + // + // This routine is only meaningful when def () is nonnull. + bool is_first_use () const; + + // Return true if this is the last use of the definition. See set_info + // for details about the ordering. + // + // This routine is only meaningful when def () is nonnull. + bool is_last_use () const; + + // Print a description of def () to PP. + void print_def (pretty_printer *pp) const; + + // Print a description of the location of the use to PP. + void print_location (pretty_printer *pp) const; + + // Print a description of the use to PP under the control of + // PP_ACCESS_* flags FLAGS. + void print (pretty_printer *pp, + unsigned int flags = PP_ACCESS_DEFAULT) const; + +private: + // If we only create a set_info splay tree for sets that are used by + // three instructions or more, then only about 16% of uses need to be in + // a splay tree. It is therefore more memory-efficient to use separate + // nodes for the splay tree, instead of storing the child nodes + // directly in the use_info. + + // Make insn_info the first (and thus directly-encoded) choice since + // insn () is read much more often than phi (). + using insn_or_phi = pointer_mux; + + // The use belongs to a list that is partitioned into three sections: + // + // (1) all uses in nondebug instructions, in reverse postorder + // + // (2) all uses in debug instructions, in reverse postorder + // + // (3) all phi nodes, in no particular order. + // + // In order to preserve memory: + // + // - The set_info just has a pointer to the first use. + // + // - The first use's "prev" pointer points to the last use. + // + // - The last use's "next" pointer points to the last use in a nondebug + // instruction, or null if there are no such uses. + using last_use_or_prev_use = pointer_mux; + using last_nondebug_insn_use_or_next_use = pointer_mux; + + use_info (insn_or_phi, resource_info, set_info *); + + use_info *last_use () const; + use_info *last_nondebug_insn_use () const; + bool calculate_is_last_nondebug_insn_use () const; + + void record_reference (rtx_obj_reference, bool); + void set_insn (insn_info *); + void set_def (set_info *set) { m_def = set; } + void set_is_live_out_use (bool value) { m_is_live_out_use = value; } + void copy_prev_from (use_info *); + void copy_next_from (use_info *); + void set_last_use (use_info *); + void set_prev_use (use_info *); + void set_last_nondebug_insn_use (use_info *); + void set_next_use (use_info *); + void clear_use_links (); + bool has_use_links (); + bool check_integrity (); + + // The location of the use. + insn_or_phi m_insn_or_phi; + + // The overloaded "prev" and "next" pointers, as described above. + last_use_or_prev_use m_last_use_or_prev_use; + last_nondebug_insn_use_or_next_use m_last_nondebug_insn_use_or_next_use; + + // The value of def (). + set_info *m_def; +}; + +// Iterators for lists of uses. +using use_iterator = list_iterator; +using reverse_use_iterator = list_iterator; + +// Like use_iterator, but specifically for uses by nondebug instructions, +// uses by any kind of instruction, and uses by phi nodes respectively. +// These iterators allow a nullptr end point even if there are other types +// of use in the same definition. +using nondebug_insn_use_iterator + = list_iterator; +using any_insn_use_iterator + = list_iterator; +using phi_use_iterator = list_iterator; + +// A view of an access_array in which every entry is known to be a use_info. +using use_array = const_derived_container; + +// An access_info that describes a definition of a resource. The definition +// can be a set or a clobber; the difference is that a set provides a known +// and potentially useful value, while a clobber provides an unknown and +// unusable value. +// +// Every definition is associated with an insn_info. All definitions of +// a given resource are stored in a linked list, maintained in reverse +// postorder. +class def_info : public access_info +{ + // Overall size: 4 LP64 words + friend class function_info; + friend class clobber_group; + +public: + // Return the instruction that contains the definition. + insn_info *insn () const { return m_insn; } + + // Return the basic block that contains the definition. + bb_info *bb () const; + + // Return the extended basic block that contains the access. + ebb_info *ebb () const; + + // Return the previous and next definitions of the same resource, + // in reverse postorder, or null if no such definition exists. + def_info *prev_def () const; + def_info *next_def () const; + + // Return true if this is the first definition in the list. + bool is_first_def () const; + + // Return true if this is the last definition in the list. + bool is_last_def () const; + + // Print the location of the definition to PP. + void print_location (pretty_printer *pp) const; + + // Print a unique identifier for this definition to PP. The identifier has + // the form :. + void print_identifier (pretty_printer *pp) const; + +protected: + def_info (insn_info *insn, resource_info resource, access_kind kind); + +private: + // In order to preserve memory, the list head only points to the first + // definition in the list. The "prev" entry of the first definition + // then points to the last definition. + using last_def_or_prev_def = pointer_mux; + + // For similar memory-saving reasons, if we want to create a splay tree + // of accesses to a resource, we hang the root off the "next" entry of + // the last definition in the list. + using splay_root_or_next_def = pointer_mux; + + void set_insn (insn_info *insn) { m_insn = insn; } + + def_info *last_def () const; + def_node *splay_root () const; + + void record_reference (rtx_obj_reference, bool); + void copy_prev_from (def_info *); + void copy_next_from (def_info *); + void set_last_def (def_info *); + void set_prev_def (def_info *); + void set_splay_root (def_node *); + void set_next_def (def_info *); + void clear_def_links (); + bool has_def_links (); + + // The location of the definition. + insn_info *m_insn; + + // The overloaded "prev" and "next" pointers, as described above. + last_def_or_prev_def m_last_def_or_prev_def; + splay_root_or_next_def m_splay_root_or_next_def; +}; + +// Iterators for lists of definitions. +using def_iterator = list_iterator; +using reverse_def_iterator = list_iterator; + +// A view of an access_array in which every entry is known to be a +// def_info. +using def_array = const_derived_container; + +// A def_info that sets the resource to a value that is both +// unknown and not useful. This is only ever used for registers, +// since memory always has some useful contents. +// +// Neighboring clobbers are grouped into clobber_groups, so that it's +// possibly to skip over all neighboring clobbers in a single step. +class clobber_info : public def_info +{ + // Overall size: 8 LP64 words + friend class default_splay_tree_accessors; + friend class default_splay_tree_accessors_with_parent; + friend class function_info; + friend class clobber_group; + +public: + using splay_tree = default_rootless_splay_tree; + + // Return true if the clobber belongs to a clobber_group, false if it + // is standalone. + bool is_in_group () const { return m_group; } + + // Return the group that the clobber is in, or null if none. + // + // Complexity: amortized O(1), worst case O(N), where N is the number + // of clobbers in the containing clobber_group. + clobber_group *group () const; + + // Print a description of the clobber to PP under the control of + // PP_ACCESS_* flags FLAGS. + void print (pretty_printer *pp, + unsigned int flags = PP_ACCESS_DEFAULT) const; + +private: + // Once normal call clobbers are taken out of the equation by + // insn_call_clobbers_notes, clobber_infos account for roughly 6% of all + // def_infos, with the rest being set_infos. clobber_infos are + // therefore much less size-sensitive than set_infos are. + // + // As noted above, we want to group neighboring clobbers together so that + // we can quickly step over them to find the previous or next "real" set. + // We also want to be able to split the group in sublinear time, + // for example when inserting a set/use pair between two clobbers + // in a group. + // + // So: + // + // - Clobbers need to have ready access to their group, so that we + // can cheaply skip over the whole group. This means that they + // need a group pointer. + // + // - We need to be able to update the group pointer lazily, so that + // the cost of updating it is counted against accesses to the clobbers + // that need updating. + // + // We also want to be able to insert clobbers into a group in + // amortized logarithmic time. + // + // We therefore use a splay tree to represent the clobbers in a group, + // with the nodes storing their parent node. It is then possible to + // perform splay operations without first getting hold of the root. + // The root of the splay tree always has a valid, up-to-date group, + // so lazy group updates can get the new group from there. + // + // Roughly 90% of clobbers have a neighboring definition in the same + // block, which means that most need to be stored in a splay tree. + // We therefore store the splay tree fields directly in the clobber_info + // rather than using a separate node object. + + clobber_info (insn_info *, unsigned int); + + void set_group (clobber_group *group) { m_group = group; } + void update_group (clobber_group *); + clobber_group *recompute_group (); + + // The child and parent nodes in the splay tree. + clobber_info *m_children[2]; + clobber_info *m_parent; + + // The last known value of group (), which might now be out of date. + clobber_group *m_group; +}; + +using clobber_tree = clobber_info::splay_tree::rooted; + +// A def_info that sets the resource to a useful value. It records +// all uses of the value in a linked list. The list is partitioned +// into three sections: +// +// (1) all uses by nondebug instructions, in reverse postorder, followed by +// (2) all uses by debug instructions, in reverse postorder, followed by +// (3) all uses by phi nodes, in no particular order. +// +// There are two cases: +// +// - If we know in advance that there is a single definition of a resource R +// and therefore decide not to use phi nodes for R, (1) and (2) contain +// all uses of R, regardless of which blocks contain the uses. (3) is +// then empty. +// +// - Otherwise, (1) only contains uses in the same extended basic block +// as the definition, and it is terminated by a use that marks the end +// of the live range for the EBB. In other words, if the resource dies +// in the EBB, the last use by a nondebug instruction marks the point at +// which it dies, otherwise there is a fake live-out use at the end of +// the EBB. +// +// Since debug instructions should not affect codegen, they opportunisticly +// attach to the same set_info as nondebug instructions where possible. +// If a nondebug instruction would attach to a degenerate phi and if no +// such phi exists, debug instructions instead attach to whichever set_info +// provides the value, regardless of where that set_info is. +class set_info : public def_info +{ + // Overall size: 6 LP64 words. + friend class function_info; + using use_splay_tree = splay_tree; + +public: + // Return the first and last uses of the set, or null if the list is empty. + // See the comment above for details about the order. + use_info *first_use () const { return m_first_use; } + use_info *last_use () const; + + // Return the first and last uses of the set by nondebug instructions, + // or null if there are no such uses. The uses are in reverse postorder. + use_info *first_nondebug_insn_use () const; + use_info *last_nondebug_insn_use () const; + + // Return the first use of the set by any kind of instruction, or null + // if there are no such uses. The uses are in the order described above. + use_info *first_any_insn_use () const; + + // Return the last use of the set by phi inputs, or null if there are no + // such uses. The phi input uses are in no particular order. + use_info *last_phi_use () const; + + // Return true if at least one nondebug instruction or phi node uses + // the set's result. This is equivalent to testing whether the set is + // ever live. + bool has_nondebug_uses () const; + + // Return true if anything uses the set's result. Note that this includes + // uses by debug instructions, so it should not be used for optimization + // decisions. + bool has_any_uses () const { return m_first_use; } + + // Return true if at least one nondebug instruction uses the set's result. + bool has_nondebug_insn_uses () const; + + // Return true if at least one phi node uses the set's result. + bool has_phi_uses () const; + + // Return true if the set and its uses are contained within a single + // extended basic block, with the set coming first. This implies + // that all uses are by instructions rather than phi nodes. + bool is_local_to_ebb () const; + + // List all the uses of the set, in the order described above. + iterator_range all_uses () const; + + // Return uses () in reverse order. + iterator_range reverse_all_uses () const; + + // List the uses of the set by nondebug instructions, in reverse postorder. + iterator_range nondebug_insn_uses () const; + + // Return nondebug_insn_uses () in reverse order. + iterator_range reverse_nondebug_insn_uses () const; + + // List the uses of the set by any kind of instruction. The list follows + // the order described above. + iterator_range all_insn_uses () const; + + // List the uses of the set by phi nodes, in no particular order. + // There is therefore no reversed equivalent of this list. + iterator_range phi_uses () const; + + // Print a description of the set to PP under the control of + // PP_ACCESS_* flags FLAGS. + void print (pretty_printer *pp, + unsigned int flags = PP_ACCESS_DEFAULT) const; + +protected: + set_info (insn_info *, resource_info, access_kind); + + // Print information about uses () to PP, continuing information printed + // about the set itself. + void print_uses_on_new_lines (pretty_printer *pp) const; + +private: + // Sets (including phis) account for about 94% of all definitions + + set_info (insn_info *, resource_info); + + void set_first_use (use_info *); + + // The first use in the list. + use_info *m_first_use; + + // The root of a splay tree of all uses, built lazily when we first + // think it's needed. + use_splay_tree m_use_tree; +}; + +// A set_info for an on-the-side phi node. The phi node is attached +// to an extended basic block EBB and has one input for each incoming edge. +// The inputs are represented as an array of use_infos, with input I +// corresponding to EDGE_PRED (EBB->first_bb ()->cfg_bb (), I). +// +// Each phi node has a densely-allocated unique identifier, which is intended +// to be suitable for bitmaps or sbitmaps. +// +// All the phi nodes in an extended basic block are chained together +// into a linked list. The list has no particular order. +class phi_info : public set_info +{ + // Overall size: 8 LP64 words + friend class function_info; + +public: + // Return the previous and next phi nodes in the extended basic block's list, + // or null if none. + phi_info *prev_phi () const { return m_prev_phi; } + phi_info *next_phi () const { return m_next_phi; } + + // Return the number of phi inputs. This is 1 for degenerate phis, + // otherwise it is equal to the number of incoming edges. + unsigned int num_inputs () const { return m_num_inputs; } + + // Return true if the phi node is degenerate, i.e. if it has only a + // single input. + bool is_degenerate () const { return m_num_inputs == 1; } + + // Return the phi node's unique identifier. + unsigned int uid () const { return m_uid; } + + // Return the array of inputs. For degenerate phi nodes, this array contains + // a single element, otherwise it has one input per incoming edge, + // with element E corresponding to incoming edge E. + use_array inputs () const; + + // Return the use_info that describes the phi input for incoming edge E. + use_info *input_use (unsigned int e) const; + + // Return the value of resource () on incoming edge E, or null if the + // value is completely undefined for that edge. + set_info *input_value (unsigned int e) const; + + // Print a description of the phi node to PP under the control of + // PP_ACCESS_* flags FLAGS. + void print (pretty_printer *pp, + unsigned int flags = PP_ACCESS_DEFAULT) const; + +private: + phi_info (insn_info *insn, resource_info resource, unsigned int uid); + + void make_degenerate (use_info *); + void set_inputs (use_array inputs); + void set_prev_phi (phi_info *prev_phi) { m_prev_phi = prev_phi; } + void set_next_phi (phi_info *next_phi) { m_next_phi = next_phi; } + void clear_phi_links () { m_prev_phi = m_next_phi = nullptr; } + bool has_phi_links () { return m_prev_phi || m_next_phi; } + + // The values returned by the accessors above. + unsigned int m_uid; + unsigned int m_num_inputs; + union + { + access_info *const *m_inputs; + access_info *m_single_input; + }; + phi_info *m_prev_phi; + phi_info *m_next_phi; +}; + +// An iterator for lists of phi nodes. +using phi_iterator = list_iterator; + +// One node in a splay tree of definitions. This base class represents +// a single def_info, but it is structured to allow derived classes +// to add a range. +class def_node +{ + // Size: 3 LP64 words. + friend class function_info; + friend class default_splay_tree_accessors; + +public: + // Return the first definition that the node represents. + def_info *first_def () const; + + // Return which type of access first_def () is. + bool contains_clobber () const { return m_clobber_or_set.is_first (); } + bool contains_set () const { return m_clobber_or_set.is_second (); } + +protected: + // More nodes are clobbers rather than sets, so put clobbers first. + // Neither choice can be null. + using clobber_or_set = pointer_mux; + + // Construct a node that represents FIRST_DEF (and possibly later + // definitions too, if called from a derived class). + def_node (clobber_or_set first_def); + + // The first definition in the node. + clobber_or_set m_clobber_or_set; + +private: + // The splay tree child nodes. + def_node *m_children[2]; +}; + +// One node in a splay tree of def_infos, representing a single set_info. +class set_node : public def_node +{ + // Overall size: 3 LP64 words. + friend class function_info; + +public: + // Return the set that the node contains. + set_info *set () const { return m_clobber_or_set.known_second (); } + + // Print a description of the node to PP. + void print (pretty_printer *pp) const; + +private: + // Construct a node for SET. + set_node (set_info *set) : def_node (set) {} +}; + +// One node in a splay tree of def_infos. This class represents +// a list of contiguous clobber_infos, in execution order. +class clobber_group : public def_node +{ + // Overall size: 5 LP64 words. + friend class function_info; + +public: + // Return the first and last clobbers in the group. The results are + // always nonnull. + clobber_info *first_clobber () const; + clobber_info *last_clobber () const { return m_last_clobber; } + + // Return true if this group has been replaced by new clobber_groups. + bool has_been_superceded () const { return !m_last_clobber; } + + // Return a list of the clobbers in the group, in execution order. + iterator_range clobbers () const; + + // Print a description of the group to PP. + void print (pretty_printer *pp) const; + +private: + clobber_group (clobber_info *clobber); + + // Set the values of first_clobber () and last_clobber (). + void set_first_clobber (clobber_info *c) { m_clobber_or_set = c; } + void set_last_clobber (clobber_info *c) { m_last_clobber = c; } + + // The value returned by last_clobber (). + clobber_info *m_last_clobber; + + // A splay tree that contains all the clobbers in the group. + // The root of the splay tree always has an up-to-date group + // pointer, but the other clobbers in the tree might not. + clobber_tree m_clobber_tree; +}; + +// A splay tree in which one node represents a standalone set_info or a +// range of consecutive clobber_infos. The nodes follow execution order +// and maintain the invariant that no two groups of clobber_infos appear +// next to each other (instead, the groups are merged). +using def_splay_tree = default_splay_tree; + +// This type represents a choice between: +// +// (1) a single definition of a resource +// (2) a node in a def_splay_tree that represents either a single +// set or a group of clobbers. +class def_mux : public pointer_mux +{ + using parent = pointer_mux; + + // Provide the same constructors as the pointer_mux. + using parent::parent; + +public: + // Return the first definition associated with this mux. If the mux holds + // a single definition, the result is that definition. If the mux holds + // a clobber_group, the result is the first clobber in the group. + def_info *first_def () const; + + // Return the last definition associated with this mux. If the mux holds + // a single definition, the result is that definition. If the mux holds + // a clobber_group, the result is the last clobber in the group. + def_info *last_def () const; + + // If the pointer represents a set_info, return that set_info, + // otherwise return null. + set_info *set () const; +}; + +// This class represents the result of looking up the definition of a +// resource at a particular point, here referred to as point P. +// There are four states: +// +// - MUX is null if there were no definitions to search. +// +// - Otherwise, COMPARISON is 0 if we found a definition at P or a +// clobber_group that spans P. MUX then contains this definition +// or clobber_group. +// +// - Otherwise, COMPARISON is less than 0 if we found the definition +// that precedes P or the group of clobbers that precedes P. MUX then +// contains this definition or clobber_group. +// +// - Otherwise, COMPARISON is greater than zero and we found the +// definition that follows P, or the group of clobbers that follows P. +// MUX then contains this definition or clobber_group. +class def_lookup +{ +public: + // If we found a clobber_group that spans P, return the definition + // that precedes the start of the group, or null if none. + // + // Otherwise, return the last definition that occurs before P, + // or null if none. + def_info *prev_def () const; + + // If we found a clobber_group that spans P, return the definition + // that follows the end of the group, or null if none. + // + // Otherwise, return the first definition that occurs after P, + // or null if none. + def_info *next_def () const; + + // If we found a set_info at P, return that set_info, otherwise return null. + set_info *matching_set () const; + + // If we found a set_info at P, return that set_info, otherwise return + // prev_def (). + def_info *matching_or_prev_def () const; + + // If we found a set_info at P, return that set_info, otherwise return + // next_def (). + def_info *matching_or_next_def () const; + + def_mux mux; + int comparison; +}; + +void pp_resource (pretty_printer *, resource_info); +void pp_access (pretty_printer *, const access_info *, + unsigned int flags = PP_ACCESS_DEFAULT); +void pp_accesses (pretty_printer *, access_array, + unsigned int flags = PP_ACCESS_DEFAULT); +void pp_def_node (pretty_printer *, const def_node *); +void pp_def_mux (pretty_printer *, def_mux); +void pp_def_lookup (pretty_printer *, def_lookup); + +} + +void dump (FILE *, rtl_ssa::resource_info); +void dump (FILE *, const rtl_ssa::access_info *, + unsigned int flags = rtl_ssa::PP_ACCESS_DEFAULT); +void dump (FILE *, rtl_ssa::access_array, + unsigned int flags = rtl_ssa::PP_ACCESS_DEFAULT); +void dump (FILE *, const rtl_ssa::def_node *); +void dump (FILE *, rtl_ssa::def_mux); +void dump (FILE *, rtl_ssa::def_lookup); + +void DEBUG_FUNCTION debug (const rtl_ssa::resource_info *); +void DEBUG_FUNCTION debug (const rtl_ssa::access_info *); +void DEBUG_FUNCTION debug (const rtl_ssa::access_array); +void DEBUG_FUNCTION debug (const rtl_ssa::def_node *); +void DEBUG_FUNCTION debug (const rtl_ssa::def_mux &); +void DEBUG_FUNCTION debug (const rtl_ssa::def_lookup &); diff --git a/gcc/rtl-ssa/blocks.cc b/gcc/rtl-ssa/blocks.cc new file mode 100644 index 0000000..5436305 --- /dev/null +++ b/gcc/rtl-ssa/blocks.cc @@ -0,0 +1,1146 @@ +// Implementation of basic-block-related functions for RTL SSA -*- C++ -*- +// Copyright (C) 2020 Free Software Foundation, Inc. +// +// This file is part of GCC. +// +// GCC is free software; you can redistribute it and/or modify it under +// the terms of the GNU General Public License as published by the Free +// Software Foundation; either version 3, or (at your option) any later +// version. +// +// GCC is distributed in the hope that it will be useful, but WITHOUT ANY +// WARRANTY; without even the implied warranty of MERCHANTABILITY or +// FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License +// for more details. +// +// You should have received a copy of the GNU General Public License +// along with GCC; see the file COPYING3. If not see +// . + +#define INCLUDE_ALGORITHM +#define INCLUDE_FUNCTIONAL +#include "config.h" +#include "system.h" +#include "coretypes.h" +#include "backend.h" +#include "rtl.h" +#include "df.h" +#include "rtl-ssa.h" +#include "rtl-ssa/internals.inl" +#include "cfganal.h" +#include "cfgrtl.h" +#include "predict.h" + +using namespace rtl_ssa; + +// See the comment above the declaration. +void +bb_info::print_identifier (pretty_printer *pp) const +{ + char tmp[3 * sizeof (index ()) + 3]; + snprintf (tmp, sizeof (tmp), "bb%d", index ()); + pp_string (pp, tmp); + if (ebb_info *ebb = this->ebb ()) + { + pp_space (pp); + pp_left_bracket (pp); + ebb->print_identifier (pp); + pp_right_bracket (pp); + } +} + +// See the comment above the declaration. +void +bb_info::print_full (pretty_printer *pp) const +{ + pp_string (pp, "basic block "); + print_identifier (pp); + pp_colon (pp); + + auto print_insn = [pp](const char *header, const insn_info *insn) + { + pp_newline_and_indent (pp, 2); + pp_string (pp, header); + pp_newline_and_indent (pp, 2); + if (insn) + pp_insn (pp, insn); + else + pp_string (pp, ""); + pp_indentation (pp) -= 4; + }; + + print_insn ("head:", head_insn ()); + + pp_newline (pp); + pp_newline_and_indent (pp, 2); + pp_string (pp, "contents:"); + if (!head_insn ()) + { + pp_newline_and_indent (pp, 2); + pp_string (pp, ""); + pp_indentation (pp) -= 2; + } + else if (auto insns = real_insns ()) + { + bool is_first = true; + for (const insn_info *insn : insns) + { + if (is_first) + is_first = false; + else + pp_newline (pp); + pp_newline_and_indent (pp, 2); + pp_insn (pp, insn); + pp_indentation (pp) -= 2; + } + } + else + { + pp_newline_and_indent (pp, 2); + pp_string (pp, "none"); + pp_indentation (pp) -= 2; + } + pp_indentation (pp) -= 2; + + pp_newline (pp); + print_insn ("end:", end_insn ()); +} + +// See the comment above the declaration. +void +ebb_call_clobbers_info::print_summary (pretty_printer *pp) const +{ + pp_string (pp, "call clobbers for ABI "); + if (m_abi) + pp_decimal_int (pp, m_abi->id ()); + else + pp_string (pp, ""); +} + +// See the comment above the declaration. +void +ebb_call_clobbers_info::print_full (pretty_printer *pp) const +{ + print_summary (pp); + pp_colon (pp); + pp_newline_and_indent (pp, 2); + auto print_node = [](pretty_printer *pp, + const insn_call_clobbers_note *note) + { + if (insn_info *insn = note->insn ()) + insn->print_identifier_and_location (pp); + else + pp_string (pp, ""); + }; + print (pp, root (), print_node); + pp_indentation (pp) -= 2; +} + +// See the comment above the declaration. +void +ebb_info::print_identifier (pretty_printer *pp) const +{ + // first_bb is populated by the constructor and so should always + // be nonnull. + auto index = first_bb ()->index (); + char tmp[3 * sizeof (index) + 4]; + snprintf (tmp, sizeof (tmp), "ebb%d", index); + pp_string (pp, tmp); +} + +// See the comment above the declaration. +void +ebb_info::print_full (pretty_printer *pp) const +{ + pp_string (pp, "extended basic block "); + print_identifier (pp); + pp_colon (pp); + + pp_newline_and_indent (pp, 2); + if (insn_info *phi_insn = this->phi_insn ()) + { + phi_insn->print_identifier_and_location (pp); + pp_colon (pp); + if (auto phis = this->phis ()) + { + bool is_first = true; + for (const phi_info *phi : phis) + { + if (is_first) + is_first = false; + else + pp_newline (pp); + pp_newline_and_indent (pp, 2); + pp_access (pp, phi, PP_ACCESS_SETTER); + pp_indentation (pp) -= 2; + } + } + else + { + pp_newline_and_indent (pp, 2); + pp_string (pp, "no phi nodes"); + pp_indentation (pp) -= 2; + } + } + else + pp_string (pp, "no phi insn"); + pp_indentation (pp) -= 2; + + for (const bb_info *bb : bbs ()) + { + pp_newline (pp); + pp_newline_and_indent (pp, 2); + pp_bb (pp, bb); + pp_indentation (pp) -= 2; + } + + for (ebb_call_clobbers_info *ecc : call_clobbers ()) + { + pp_newline (pp); + pp_newline_and_indent (pp, 2); + pp_ebb_call_clobbers (pp, ecc); + pp_indentation (pp) -= 2; + } +} + +// Add a dummy use to mark that DEF is live out of BB's EBB at the end of BB. +void +function_info::add_live_out_use (bb_info *bb, set_info *def) +{ + // There is nothing to do if DEF is an artificial definition at the end + // of BB. In that case the definitino is rooted at the end of the block + // and we wouldn't gain anything by inserting a use immediately after it. + // If we did want to insert a use, we'd need to associate it with a new + // instruction that comes after bb->end_insn (). + if (def->insn () == bb->end_insn ()) + return; + + // If the end of the block already has an artificial use, that use + // acts to make DEF live at the appropriate point. + unsigned int regno = def->regno (); + if (find_access (bb->end_insn ()->uses (), regno)) + return; + + // Currently there is no need to maintain a backward link from the end + // instruction to the list of live-out uses. Such a list would be + // expensive to update if it was represented using the usual insn_info + // access arrays. + use_info *use = allocate (bb->end_insn (), def->resource (), def); + use->set_is_live_out_use (true); + add_use (use); +} + +// Return true if all nondebug uses of DEF are live-out uses. +static bool +all_uses_are_live_out_uses (set_info *def) +{ + for (use_info *use : def->all_uses ()) + if (!use->is_in_debug_insn () && !use->is_live_out_use ()) + return false; + return true; +} + +// SET, if nonnull, is a definition of something that is live out from BB. +// Return the live-out value itself. +set_info * +function_info::live_out_value (bb_info *bb, set_info *set) +{ + // Degenerate phis only exist to provide a definition for uses in the + // same EBB. The live-out value is the same as the live-in value. + if (auto *phi = safe_dyn_cast (set)) + if (phi->is_degenerate ()) + { + set = phi->input_value (0); + + // Remove the phi if it turned out to be useless. This is + // mainly useful for memory, because we don't know ahead of time + // whether a block will use memory or not. + if (bb == bb->ebb ()->last_bb () && all_uses_are_live_out_uses (phi)) + replace_phi (phi, set); + } + + return set; +} + +// Add PHI to EBB and enter it into the function's hash table. +void +function_info::append_phi (ebb_info *ebb, phi_info *phi) +{ + phi_info *first_phi = ebb->first_phi (); + if (first_phi) + first_phi->set_prev_phi (phi); + phi->set_next_phi (first_phi); + ebb->set_first_phi (phi); + add_def (phi); +} + +// Remove PHI from its current position in the SSA graph. +void +function_info::remove_phi (phi_info *phi) +{ + phi_info *next = phi->next_phi (); + phi_info *prev = phi->prev_phi (); + + if (next) + next->set_prev_phi (prev); + + if (prev) + prev->set_next_phi (next); + else + phi->ebb ()->set_first_phi (next); + + remove_def (phi); + phi->clear_phi_links (); +} + +// Remove PHI from the SSA graph and free its memory. +void +function_info::delete_phi (phi_info *phi) +{ + gcc_assert (!phi->has_any_uses ()); + + // Remove the inputs to the phi. + for (use_info *input : phi->inputs ()) + remove_use (input); + + remove_phi (phi); + + phi->set_next_phi (m_free_phis); + m_free_phis = phi; +} + +// If possible, remove PHI and replace all uses with NEW_VALUE. +void +function_info::replace_phi (phi_info *phi, set_info *new_value) +{ + auto update_use = [&](use_info *use) + { + remove_use (use); + use->set_def (new_value); + add_use (use); + }; + + if (new_value) + for (use_info *use : phi->nondebug_insn_uses ()) + if (!use->is_live_out_use ()) + { + // We need to keep the phi around for its local uses. + // Turn it into a degenerate phi, if it isn't already. + use_info *use = phi->input_use (0); + if (use->def () != new_value) + update_use (use); + + if (phi->is_degenerate ()) + return; + + phi->make_degenerate (use); + + // Redirect all phi users to NEW_VALUE. + while (use_info *phi_use = phi->last_phi_use ()) + update_use (phi_use); + + return; + } + + // Replace the uses. We can discard uses that only existed for the + // sake of marking live-out values, since the resource is now transparent + // in the phi's EBB. + while (use_info *use = phi->last_use ()) + if (use->is_live_out_use ()) + remove_use (use); + else + update_use (use); + + delete_phi (phi); +} + +// Create and return a phi node for EBB. RESOURCE is the resource that +// the phi node sets (and thus that all the inputs set too). NUM_INPUTS +// is the number of inputs, which is 1 for a degenerate phi. INPUTS[I] +// is a set_info that gives the value of input I, or null if the value +// is either unknown or uninitialized. If NUM_INPUTS > 1, this array +// is allocated on the main obstack and can be reused for the use array. +// +// Add the created phi node to its basic block and enter it into the +// function's hash table. +phi_info * +function_info::create_phi (ebb_info *ebb, resource_info resource, + access_info **inputs, unsigned int num_inputs) +{ + phi_info *phi = m_free_phis; + if (phi) + { + m_free_phis = phi->next_phi (); + *phi = phi_info (ebb->phi_insn (), resource, phi->uid ()); + } + else + { + phi = allocate (ebb->phi_insn (), resource, m_next_phi_uid); + m_next_phi_uid += 1; + } + + // Convert the array of set_infos into an array of use_infos. Also work + // out what mode the phi should have. + machine_mode new_mode = resource.mode; + for (unsigned int i = 0; i < num_inputs; ++i) + { + auto *input = safe_as_a (inputs[i]); + auto *use = allocate (phi, resource, input); + add_use (use); + inputs[i] = use; + if (input) + new_mode = combine_modes (new_mode, input->mode ()); + } + + phi->set_inputs (use_array (inputs, num_inputs)); + phi->set_mode (new_mode); + + append_phi (ebb, phi); + + return phi; +} + +// Create and return a degenerate phi for EBB whose input comes from DEF. +// This is used in cases where DEF is known to be available on entry to +// EBB but was not previously used within it. If DEF is for a register, +// there are two cases: +// +// (1) DEF was already live on entry to EBB but was previously transparent +// within it. +// +// (2) DEF was not previously live on entry to EBB and is being made live +// by this update. +// +// At the moment, this function only handles the case in which EBB has a +// single predecessor block and DEF is defined in that block's EBB. +phi_info * +function_info::create_degenerate_phi (ebb_info *ebb, set_info *def) +{ + access_info *input = def; + phi_info *phi = create_phi (ebb, def->resource (), &input, 1); + if (def->is_reg ()) + { + unsigned int regno = def->regno (); + + // Find the single predecessor mentioned above. + basic_block pred_cfg_bb = single_pred (ebb->first_bb ()->cfg_bb ()); + bb_info *pred_bb = this->bb (pred_cfg_bb); + + if (!bitmap_set_bit (DF_LR_IN (ebb->first_bb ()->cfg_bb ()), regno)) + { + // The register was not previously live on entry to EBB and + // might not have been live on exit from PRED_BB either. + if (bitmap_set_bit (DF_LR_OUT (pred_cfg_bb), regno)) + add_live_out_use (pred_bb, def); + } + else + { + // The register was previously live in to EBB. Add live-out uses + // at the appropriate points. + insn_info *next_insn = nullptr; + if (def_info *next_def = phi->next_def ()) + next_insn = next_def->insn (); + for (bb_info *bb : ebb->bbs ()) + { + if ((next_insn && *next_insn <= *bb->end_insn ()) + || !bitmap_bit_p (DF_LR_OUT (bb->cfg_bb ()), regno)) + break; + add_live_out_use (bb, def); + } + } + } + return phi; +} + +// Create a bb_info for CFG_BB, given that no such structure currently exists. +bb_info * +function_info::create_bb_info (basic_block cfg_bb) +{ + bb_info *bb = allocate (cfg_bb); + gcc_checking_assert (!m_bbs[cfg_bb->index]); + m_bbs[cfg_bb->index] = bb; + return bb; +} + +// Add BB to the end of the list of blocks. +void +function_info::append_bb (bb_info *bb) +{ + if (m_last_bb) + m_last_bb->set_next_bb (bb); + else + m_first_bb = bb; + bb->set_prev_bb (m_last_bb); + m_last_bb = bb; +} + +// Called while building SSA form using BI, with BI.current_bb being +// the entry block. +// +// Create the entry block instructions and their definitions. The only +// useful instruction is the end instruction, which carries definitions +// for the values that are live on entry to the function. However, it +// seems simpler to create a head instruction too, rather than force all +// users of the block information to treat the entry block as a special case. +void +function_info::add_entry_block_defs (build_info &bi) +{ + bb_info *bb = bi.current_bb; + basic_block cfg_bb = bi.current_bb->cfg_bb (); + auto *lr_info = DF_LR_BB_INFO (cfg_bb); + + bb->set_head_insn (append_artificial_insn (bb)); + insn_info *insn = append_artificial_insn (bb); + bb->set_end_insn (insn); + + start_insn_accesses (); + + // Using LR to derive the liveness information means that we create an + // entry block definition for upwards exposed registers. These registers + // are sometimes genuinely uninitialized. However, some targets also + // create a pseudo PIC base register and only initialize it later. + // Handling that case correctly seems more important than optimizing + // uninitialized uses. + unsigned int regno; + bitmap_iterator in_bi; + EXECUTE_IF_SET_IN_BITMAP (&lr_info->out, 0, regno, in_bi) + { + auto *set = allocate (insn, full_register (regno)); + append_def (set); + m_temp_defs.safe_push (set); + bi.record_reg_def (regno, set); + } + + // Create a definition that reflects the state of memory on entry to + // the function. + auto *set = allocate (insn, memory); + append_def (set); + m_temp_defs.safe_push (set); + bi.record_mem_def (set); + + finish_insn_accesses (insn); +} + +// Called while building SSA form using BI. Create phi nodes for the +// current EBB, leaving backedge inputs to be filled in later. Set +// bi.last_access to the values that are live on entry to the EBB, +// regardless of whether or not they are phi nodes. +void +function_info::add_phi_nodes (build_info &bi) +{ + ebb_info *ebb = bi.current_ebb; + basic_block cfg_bb = ebb->first_bb ()->cfg_bb (); + auto *lr_info = DF_LR_BB_INFO (cfg_bb); + + // Get a local cache of the predecessor blocks' live out values. + unsigned int num_preds = EDGE_COUNT (cfg_bb->preds); + auto_vec pred_live_outs (num_preds); + bool has_backedge = false; + bool has_eh_edge = false; + edge e; + edge_iterator ei; + FOR_EACH_EDGE (e, ei, cfg_bb->preds) + { + bb_info *pred_bb = this->bb (e->src); + const bb_live_out_info *live_out = &bi.bb_live_out[e->src->index]; + + // In LR (but not LIVE), the registers live on entry to a block must + // normally be a subset of the registers live on exit from any + // given predecessor block. The exceptions are EH edges, which + // implicitly clobber all registers in eh_edge_abi.full_reg_clobbers (). + // Thus if a register is upwards exposed in an EH handler, it won't + // be propagated across the EH edge. + // + // Excluding that special case, all registers live on entry to + // EBB are also live on exit from PRED_BB and were (or will be) + // considered when creating LIVE_OUT. + gcc_checking_assert ((e->flags & EDGE_EH) + || !bitmap_intersect_compl_p (&lr_info->in, + DF_LR_OUT (e->src))); + if (!pred_bb || !pred_bb->head_insn ()) + { + has_backedge = true; + live_out = nullptr; + } + has_eh_edge |= (e->flags & EDGE_EH); + pred_live_outs.quick_push (live_out); + } + + // PRED_REG_INDICES[I] tracks the index into PRED_LIVE_OUTS[I]->reg_values + // of the first unused entry. + auto_vec pred_reg_indices (num_preds); + pred_reg_indices.quick_grow_cleared (num_preds); + + // Use this array to build up the list of inputs to each phi. + m_temp_defs.safe_grow (num_preds); + + // Return true if the current phi is degenerate, i.e. if all its inputs + // are the same. + auto is_degenerate_phi = [&]() + { + if (has_backedge) + return false; + + for (unsigned int i = 1; i < num_preds; ++i) + if (m_temp_defs[i] != m_temp_defs[0]) + return false; + + return true; + }; + + // Finish calculating the live-in value for RESOURCE. Decide how to + // represent the value of RESOURCE on entry to EBB and return its definition. + auto finish_phi = [&](resource_info resource) -> set_info * + { + access_info **inputs; + unsigned int num_inputs; + if (is_degenerate_phi ()) + { + auto *input = safe_as_a (m_temp_defs[0]); + if (!input) + // The live-in value is completely uninitialized. + return nullptr; + + unsigned int regno = input->regno (); + if (input->is_reg () && !bitmap_bit_p (bi.ebb_use, regno)) + // The live-in value comes from a single source and there + // are no uses of it within the EBB itself. We therefore + // don't need a phi node. + return input; + + // The live-in value comes from a single source and might be + // used by the EBB itself. Create a degenerate phi for it. + inputs = m_temp_defs.begin (); + num_inputs = 1; + } + else + { + obstack_grow (&m_obstack, m_temp_defs.address (), + num_preds * sizeof (access_info *)); + inputs = static_cast (obstack_finish (&m_obstack)); + num_inputs = num_preds; + } + return create_phi (ebb, resource, inputs, num_inputs); + }; + + if (bi.ebb_live_in_for_debug) + bitmap_clear (bi.ebb_live_in_for_debug); + + // Get the definition of each live input register, excluding registers + // that are known to have a single definition that dominates all uses. + unsigned int regno; + bitmap_iterator in_bi; + EXECUTE_IF_AND_IN_BITMAP (&lr_info->in, m_potential_phi_regs, + 0, regno, in_bi) + { + for (unsigned int pred_i = 0; pred_i < num_preds; ++pred_i) + { + set_info *input = nullptr; + if (const bb_live_out_info *pred_live_out = pred_live_outs[pred_i]) + { + // Skip over registers that aren't live on entry to this block. + unsigned int reg_i = pred_reg_indices[pred_i]; + while (reg_i < pred_live_out->num_reg_values + && pred_live_out->reg_values[reg_i]->regno () < regno) + reg_i += 1; + + // As we asserted above, REGNO is live out from the predecessor + // block, at least by the LR reckoning. But there are three + // cases: + // + // (1) The live-out value is well-defined (the normal case), + // with the definition coming either from the block itself + // or from a predecessor block. In this case reg_values + // has a set_info entry for the register. + // + // (2) The live-out value was not modified by the predecessor + // EBB and did not have a defined value on input to that + // EBB either. In this case reg_values has no entry for + // the register. + // + // (3) The live-out value was modified by the predecessor EBB, + // but the final modification was a clobber rather than + // a set. In this case reg_values again has no entry for + // the register. + // + // The phi input for (2) and (3) is undefined, which we + // represent as a null set_info. + if (reg_i < pred_live_out->num_reg_values) + { + set_info *set = pred_live_out->reg_values[reg_i]; + if (set->regno () == regno) + { + input = set; + reg_i += 1; + } + } + + // Fully call-clobbered values do not survive across EH edges. + // In particular, if a call that normally sets a result register + // throws an exception, the set of the result register should + // not be treated as live on entry to the EH handler. + if (has_eh_edge + && HARD_REGISTER_NUM_P (regno) + && eh_edge_abi.clobbers_full_reg_p (regno) + && (EDGE_PRED (cfg_bb, pred_i)->flags & EDGE_EH)) + input = nullptr; + + pred_reg_indices[pred_i] = reg_i; + } + m_temp_defs[pred_i] = input; + } + // Later code works out the correct mode of the phi. Use BLKmode + // as a placeholder for now. + bi.record_reg_def (regno, finish_phi ({ E_BLKmode, regno })); + if (bi.ebb_live_in_for_debug) + bitmap_set_bit (bi.ebb_live_in_for_debug, regno); + } + + // Repeat the process above for memory. + for (unsigned int pred_i = 0; pred_i < num_preds; ++pred_i) + { + set_info *input = nullptr; + if (const bb_live_out_info *pred_live_out = pred_live_outs[pred_i]) + input = pred_live_out->mem_value; + m_temp_defs[pred_i] = input; + } + bi.record_mem_def (finish_phi (memory)); + + m_temp_defs.truncate (0); +} + +// Called while building SSA form using BI. +// +// If FLAGS is DF_REF_AT_TOP, create the head insn for BI.current_bb +// and populate its uses and definitions. If FLAGS is 0, do the same +// for the end insn. +void +function_info::add_artificial_accesses (build_info &bi, df_ref_flags flags) +{ + bb_info *bb = bi.current_bb; + basic_block cfg_bb = bb->cfg_bb (); + auto *lr_info = DF_LR_BB_INFO (cfg_bb); + df_ref ref; + + insn_info *insn; + if (flags == DF_REF_AT_TOP) + { + if (cfg_bb->index == EXIT_BLOCK) + insn = append_artificial_insn (bb); + else + insn = append_artificial_insn (bb, bb_note (cfg_bb)); + bb->set_head_insn (insn); + } + else + { + insn = append_artificial_insn (bb); + bb->set_end_insn (insn); + } + + start_insn_accesses (); + + FOR_EACH_ARTIFICIAL_USE (ref, cfg_bb->index) + if ((DF_REF_FLAGS (ref) & DF_REF_AT_TOP) == flags) + { + unsigned int regno = DF_REF_REGNO (ref); + machine_mode mode = GET_MODE (DF_REF_REAL_REG (ref)); + resource_info resource { mode, regno }; + + // A definition must be available. + gcc_checking_assert (bitmap_bit_p (&lr_info->in, regno) + || (flags != DF_REF_AT_TOP + && bitmap_bit_p (&lr_info->def, regno))); + set_info *def = bi.current_reg_value (regno); + auto *use = allocate (insn, resource, def); + add_use (use); + m_temp_uses.safe_push (use); + } + + // Track the return value of memory by adding an artificial use of + // memory at the end of the exit block. + if (flags == 0 && cfg_bb->index == EXIT_BLOCK) + { + auto *use = allocate (insn, memory, bi.current_mem_value ()); + add_use (use); + m_temp_uses.safe_push (use); + } + + FOR_EACH_ARTIFICIAL_DEF (ref, cfg_bb->index) + if ((DF_REF_FLAGS (ref) & DF_REF_AT_TOP) == flags) + { + unsigned int regno = DF_REF_REGNO (ref); + machine_mode mode = GET_MODE (DF_REF_REAL_REG (ref)); + resource_info resource { mode, regno }; + + // If the value isn't used later in the block and isn't live + // on exit, we could instead represent the definition as a + // clobber_info. However, that case should be relatively + // rare and set_info is any case more compact than clobber_info. + set_info *def = allocate (insn, resource); + append_def (def); + m_temp_defs.safe_push (def); + bi.record_reg_def (regno, def); + } + + // Model the effect of a memory clobber on an incoming edge by adding + // a fake definition of memory at the start of the block. We don't need + // to add a use of the phi node because memory is implicitly always live. + if (flags == DF_REF_AT_TOP && has_abnormal_call_or_eh_pred_edge_p (cfg_bb)) + { + set_info *def = allocate (insn, memory); + append_def (def); + m_temp_defs.safe_push (def); + bi.record_mem_def (def); + } + + finish_insn_accesses (insn); +} + +// Called while building SSA form using BI. Create insn_infos for all +// relevant instructions in BI.current_bb. +void +function_info::add_block_contents (build_info &bi) +{ + basic_block cfg_bb = bi.current_bb->cfg_bb (); + rtx_insn *insn; + FOR_BB_INSNS (cfg_bb, insn) + if (INSN_P (insn)) + add_insn_to_block (bi, insn); +} + +// Called while building SSA form using BI. Use BI.bb_live_out to record +// the values that are live out from BI.current_bb. +void +function_info::record_block_live_out (build_info &bi) +{ + bb_info *bb = bi.current_bb; + ebb_info *ebb = bi.current_ebb; + basic_block cfg_bb = bb->cfg_bb (); + bb_live_out_info *live_out = &bi.bb_live_out[bb->index ()]; + auto *lr_info = DF_LR_BB_INFO (bb->cfg_bb ()); + + // Calculate which subset of m_potential_phi_regs is live out from EBB + // at the end of BB. + auto_bitmap live_out_from_ebb; + edge e; + edge_iterator ei; + FOR_EACH_EDGE (e, ei, cfg_bb->succs) + { + bb_info *dest_bb = this->bb (e->dest); + if (!dest_bb || dest_bb->ebb () != ebb) + bitmap_ior_and_into (live_out_from_ebb, DF_LR_IN (e->dest), + m_potential_phi_regs); + } + + // Record the live-out register values. + unsigned int regno; + bitmap_iterator out_bi; + EXECUTE_IF_AND_IN_BITMAP (&lr_info->out, m_potential_phi_regs, + 0, regno, out_bi) + if (set_info *value = live_out_value (bb, bi.current_reg_value (regno))) + { + if (value->ebb () == ebb && bitmap_bit_p (live_out_from_ebb, regno)) + add_live_out_use (bb, value); + obstack_ptr_grow (&m_temp_obstack, value); + } + + live_out->num_reg_values = (obstack_object_size (&m_temp_obstack) + / sizeof (set_info *)); + auto *data = obstack_finish (&m_temp_obstack); + live_out->reg_values = static_cast (data); + + live_out->mem_value = live_out_value (bb, bi.current_mem_value ()); +} + +// Called while building SSA form using BI. Check if BI.current_bb has +// any outgoing backedges. If so, use the up-to-date contents of +// BI.bb_live_out to populate the associated inputs of any phi nodes. +void +function_info::populate_backedge_phis (build_info &bi) +{ + bb_info *bb = bi.current_bb; + basic_block cfg_bb = bb->cfg_bb (); + const bb_live_out_info *live_out = &bi.bb_live_out[bb->index ()]; + + edge e; + edge_iterator ei; + FOR_EACH_EDGE (e, ei, cfg_bb->succs) + { + // Check if this edge counts as a backedge in the current traversal. + bb_info *succ_bb = this->bb (e->dest); + if (!succ_bb || !succ_bb->head_insn ()) + continue; + + // Although the phis do not keep a defined order long-term, they are + // still in reverse regno order at this point. We can therefore use + // a merge operation on the phis and the live-out values. + unsigned int input_i = e->dest_idx; + int reg_i = live_out->num_reg_values - 1; + for (phi_info *phi : succ_bb->ebb ()->phis ()) + { + set_info *input = nullptr; + if (phi->is_mem ()) + input = live_out->mem_value; + else + { + // Skip over any intervening live-out values. + unsigned int regno = phi->regno (); + while (reg_i >= 0) + { + set_info *reg_value = live_out->reg_values[reg_i]; + if (reg_value->regno () < regno) + break; + reg_i -= 1; + if (reg_value->regno () == regno) + { + input = reg_value; + break; + } + } + } + if (input) + { + use_info *use = phi->input_use (input_i); + gcc_assert (!use->def ()); + use->set_def (input); + add_use (use); + } + } + } +} + +// Return true if it would be better to continue an EBB across NEW_EDGE +// rather than across OLD_EDGE, given that both edges are viable candidates. +// This is not a total ordering. +static bool +better_ebb_edge_p (edge new_edge, edge old_edge) +{ + // Prefer the likeliest edge. + if (new_edge->probability.initialized_p () + && old_edge->probability.initialized_p () + && !(old_edge->probability == new_edge->probability)) + return old_edge->probability < new_edge->probability; + + // If both edges are equally likely, prefer a fallthru edge. + if (new_edge->flags & EDGE_FALLTHRU) + return true; + if (old_edge->flags & EDGE_FALLTHRU) + return false; + + // Otherwise just stick with OLD_EDGE. + return false; +} + +// Pick and return the next basic block in an EBB that currently ends with BB. +// Return null if the EBB must end with BB. +static basic_block +choose_next_block_in_ebb (basic_block bb) +{ + // Although there's nothing in principle wrong with having an EBB that + // starts with the entry block and includes later blocks, there's not + // really much point either. Keeping the entry block separate means + // that uses of arguments consistently occur through phi nodes, rather + // than the arguments sometimes appearing to come from an EBB-local + // definition instead. + if (bb->index == ENTRY_BLOCK) + return nullptr; + + bool optimize_for_speed_p = optimize_bb_for_speed_p (bb); + edge best_edge = nullptr; + edge e; + edge_iterator ei; + FOR_EACH_EDGE (e, ei, bb->succs) + if (!(e->flags & EDGE_COMPLEX) + && e->dest->index != EXIT_BLOCK + && single_pred_p (e->dest) + && optimize_for_speed_p == optimize_bb_for_speed_p (e->dest) + && (!best_edge || better_ebb_edge_p (e, best_edge))) + best_edge = e; + + return best_edge ? best_edge->dest : nullptr; +} + +// Partition the function's blocks into EBBs and build SSA form for all +// EBBs in the function. +void +function_info::process_all_blocks () +{ + auto temps = temp_watermark (); + unsigned int num_bb_indices = last_basic_block_for_fn (m_fn); + + // Compute the starting reverse postorder. We tweak this later to try + // to get better EBB assignments. + auto *postorder = new int[n_basic_blocks_for_fn (m_fn)]; + unsigned int postorder_num + = pre_and_rev_post_order_compute (nullptr, postorder, true); + gcc_assert (int (postorder_num) <= n_basic_blocks_for_fn (m_fn)); + + // Construct the working state for this function and its subroutines. + build_info bi; + bi.last_access = XOBNEWVEC (&m_temp_obstack, access_info *, m_num_regs + 1); + memset (bi.last_access, 0, (m_num_regs + 1) * sizeof (set_info *)); + + // The bb_live_out array shouldn't need to be initialized, since we'll + // always write to an entry before reading from it. But poison the + // contents when checking, just to make sure we don't accidentally use + // an uninitialized value. + bi.bb_live_out = XOBNEWVEC (&m_temp_obstack, bb_live_out_info, + num_bb_indices); + if (flag_checking) + memset (bi.bb_live_out, 0xaf, + num_bb_indices * sizeof (bb_live_out_info)); + + // Only pay the overhead of recording a separate live-in bitmap if + // there are debug instructions that might need it. + auto_bitmap ebb_live_in; + if (MAY_HAVE_DEBUG_INSNS) + { + bi.ebb_live_in_for_debug = ebb_live_in; + // The bitmap is tested using individual bit operations, so optimize + // for that case. + bitmap_tree_view (ebb_live_in); + } + else + bi.ebb_live_in_for_debug = nullptr; + + // Iterate over the blocks in reverse postorder. In cases where + // multiple possible orders exist, prefer orders that chain blocks + // together into EBBs. If multiple possible EBBs exist, try to pick + // the ones that are most likely to be profitable. + auto_vec ebb; + auto_bitmap ebb_use_tmp; + auto_bitmap ebb_def_tmp; + for (unsigned int i = 0; i < postorder_num; ++i) + if (!m_bbs[postorder[i]]) + { + // Choose and create the blocks that should form the next EBB, + // and calculate the set of registers that the EBB uses and defines + // Only do actual bitmap operations if the EBB contains multiple + // blocks. + basic_block cfg_bb = BASIC_BLOCK_FOR_FN (m_fn, postorder[i]); + bi.ebb_use = &DF_LR_BB_INFO (cfg_bb)->use; + bi.ebb_def = &DF_LR_BB_INFO (cfg_bb)->def; + ebb.safe_push (create_bb_info (cfg_bb)); + cfg_bb = choose_next_block_in_ebb (cfg_bb); + if (cfg_bb) + { + // An EBB with two blocks. + bitmap_ior (ebb_use_tmp, bi.ebb_use, &DF_LR_BB_INFO (cfg_bb)->use); + bitmap_ior (ebb_def_tmp, bi.ebb_def, &DF_LR_BB_INFO (cfg_bb)->def); + bi.ebb_use = ebb_use_tmp; + bi.ebb_def = ebb_def_tmp; + ebb.safe_push (create_bb_info (cfg_bb)); + cfg_bb = choose_next_block_in_ebb (cfg_bb); + while (cfg_bb) + { + // An EBB with three or more blocks. + bitmap_ior_into (bi.ebb_use, &DF_LR_BB_INFO (cfg_bb)->use); + bitmap_ior_into (bi.ebb_def, &DF_LR_BB_INFO (cfg_bb)->def); + ebb.safe_push (create_bb_info (cfg_bb)); + cfg_bb = choose_next_block_in_ebb (cfg_bb); + } + } + + // Create the EBB itself. + bi.current_ebb = allocate (ebb[0], ebb.last ()); + for (bb_info *bb : ebb) + { + bb->set_ebb (bi.current_ebb); + append_bb (bb); + } + + // Populate the contents of the EBB. + bi.current_ebb->set_phi_insn (append_artificial_insn (ebb[0])); + if (ebb[0]->index () == ENTRY_BLOCK) + { + gcc_assert (ebb.length () == 1); + bi.current_bb = ebb[0]; + add_entry_block_defs (bi); + record_block_live_out (bi); + } + else if (EDGE_COUNT (ebb[0]->cfg_bb ()->preds) == 0) + // Leave unreachable blocks empty, since there is no useful + // liveness information for them, and anything they do will + // be wasted work. In a cleaned-up cfg, the only unreachable + // block we should see is the exit block of a noreturn function. + for (bb_info *bb : ebb) + { + bb->set_head_insn (append_artificial_insn (bb)); + bb->set_end_insn (append_artificial_insn (bb)); + } + else + { + add_phi_nodes (bi); + for (bb_info *bb : ebb) + { + bi.current_bb = bb; + add_artificial_accesses (bi, DF_REF_AT_TOP); + if (bb->index () != EXIT_BLOCK) + add_block_contents (bi); + add_artificial_accesses (bi, df_ref_flags ()); + record_block_live_out (bi); + populate_backedge_phis (bi); + } + } + ebb.truncate (0); + } + + delete[] postorder; +} + +// Print a description of CALL_CLOBBERS to PP. +void +rtl_ssa::pp_ebb_call_clobbers (pretty_printer *pp, + const ebb_call_clobbers_info *call_clobbers) +{ + if (!call_clobbers) + pp_string (pp, ""); + else + call_clobbers->print_full (pp); +} + +// Print a description of BB to PP. +void +rtl_ssa::pp_bb (pretty_printer *pp, const bb_info *bb) +{ + if (!bb) + pp_string (pp, ""); + else + bb->print_full (pp); +} + +// Print a description of EBB to PP +void +rtl_ssa::pp_ebb (pretty_printer *pp, const ebb_info *ebb) +{ + if (!ebb) + pp_string (pp, ""); + else + ebb->print_full (pp); +} + +// Print a description of CALL_CLOBBERS to FILE. +void +dump (FILE *file, const ebb_call_clobbers_info *call_clobbers) +{ + dump_using (file, pp_ebb_call_clobbers, call_clobbers); +} + +// Print a description of BB to FILE. +void +dump (FILE *file, const bb_info *bb) +{ + dump_using (file, pp_bb, bb); +} + +// Print a description of EBB to FILE. +void +dump (FILE *file, const ebb_info *ebb) +{ + dump_using (file, pp_ebb, ebb); +} + +// Debug interfaces to the dump routines above. +void debug (const ebb_call_clobbers_info *x) { dump (stderr, x); } +void debug (const bb_info *x) { dump (stderr, x); } +void debug (const ebb_info *x) { dump (stderr, x); } diff --git a/gcc/rtl-ssa/blocks.h b/gcc/rtl-ssa/blocks.h new file mode 100644 index 0000000..f173e6f --- /dev/null +++ b/gcc/rtl-ssa/blocks.h @@ -0,0 +1,301 @@ +// Basic-block-related classes for RTL SSA -*- C++ -*- +// Copyright (C) 2020 Free Software Foundation, Inc. +// +// This file is part of GCC. +// +// GCC is free software; you can redistribute it and/or modify it under +// the terms of the GNU General Public License as published by the Free +// Software Foundation; either version 3, or (at your option) any later +// version. +// +// GCC is distributed in the hope that it will be useful, but WITHOUT ANY +// WARRANTY; without even the implied warranty of MERCHANTABILITY or +// FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License +// for more details. +// +// You should have received a copy of the GNU General Public License +// along with GCC; see the file COPYING3. If not see +// . + +namespace rtl_ssa { + +// SSA-related information about a basic block. Each block contains +// the following, which are conceptually executed in order: +// +// - an artificial "head" insn_info that holds artificial uses and definitions +// for the start of the block. +// +// - one insn_info for each "real" instruction in the block +// (i.e. those that have an RTL pattern). +// +// - an artificial "end" insn_info that holds artificial uses and definitions +// for the end of the block. +// +// Blocks are grouped together into extended basic blocks. In cases where +// multiple EBBs exist (such as in a full diamond), we try to pick the one +// that's most frequently executed. +// +// Blocks are chained together in reverse postorder. (Rather than use a +// list, we could instead have stored the index of the block in the overall +// postorder. However, using lists should make it cheaper to update the +// information after trivial CFG manipulations.) +class bb_info +{ + // Size: 6 LP64 words. + friend class function_info; + +public: + // Return the previous basic block in reverse postorder, or null if this + // is the entry block. + bb_info *prev_bb () const { return m_prev_bb; } + + // Return the next basic block in reverse postorder, or null if this + // is the exit block. + bb_info *next_bb () const { return m_next_bb; } + + // Return true if this block is the function's entry block. + bool is_entry_block () const { return !m_prev_bb; } + + // Return true if this block is the function's exit block. + bool is_exit_block () const { return !m_next_bb; } + + // Return the underlying basic_block structure. + basic_block cfg_bb () const { return m_cfg_bb; } + + // Return the unique identifier of the underlying basic_block. These uids + // do not follow any particular order. + unsigned int index () const { return m_cfg_bb->index; } + + // Return the EBB that contains this block. + ebb_info *ebb () const { return m_ebb; } + + // Return a list of all the instructions in the block, in execution order. + // The list includes the head and end instructions described above. + // + // Iterations over the list will pick up any new instructions that are + // inserted after the iterator's current instruction. + iterator_range all_insns () const; + + // Like all_insns (), except that the instructions are in reverse order. + // + // Iterations over the list will pick up any new instructions that are + // inserted before the iterator's current instruction. + iterator_range reverse_all_insns () const; + + // Like all_insns (), but without the debug instructions. + iterator_range nondebug_insns () const; + + // Like reverse_all_insns (), but without the debug instructions. + iterator_range + reverse_nondebug_insns () const; + + // Like all_insns (), but without the artificial instructions. + iterator_range real_insns () const; + + // Like reverse_all_insns (), but without the artificial instructions. + iterator_range reverse_real_insns () const; + + // Like real_insns (), but without the debug instructions. + iterator_range real_nondebug_insns () const; + + // Like reverse_real_insns (), but without the debug instructions. + iterator_range + reverse_real_nondebug_insns () const; + + // Return the instruction that holds the artificial uses and + // definitions at the head of the block. The associated RTL insn + // is the block head note. + // + // This instruction always exists, even if it has no uses and definitions. + insn_info *head_insn () const { return m_head_insn; } + + // Return the instruction that holds the artificial uses and definitions + // at the end of the block. There is no associated RTL insn. + // + // This instruction always exists, even if it has no uses and definitions. + insn_info *end_insn () const { return m_end_insn; } + + // Print "bb" + index () to PP. + void print_identifier (pretty_printer *pp) const; + + // Print a full description of the block to PP. + void print_full (pretty_printer *) const; + +private: + bb_info (basic_block); + + void set_prev_bb (bb_info *bb) { m_prev_bb = bb; } + void set_next_bb (bb_info *bb) { m_next_bb = bb; } + void set_cfg_bb (basic_block cfg_bb) { m_cfg_bb = cfg_bb; } + void set_ebb (ebb_info *ebb) { m_ebb = ebb; } + void set_head_insn (insn_info *insn) { m_head_insn = insn; } + void set_end_insn (insn_info *insn) { m_end_insn = insn; } + + // The values returned by the functions above. + bb_info *m_prev_bb; + bb_info *m_next_bb; + basic_block m_cfg_bb; + ebb_info *m_ebb; + insn_info *m_head_insn; + insn_info *m_end_insn; +}; + +// Iterators for lists of basic blocks. +using bb_iterator = list_iterator; +using reverse_bb_iterator = list_iterator; + +// This class collects together instructions for which has_call_clobbers () +// is true, storing them in a splay tree that follows reverse postorder. +// Instances of the class form a singly-linked list, with one instance +// per predefined_function_abi. +class ebb_call_clobbers_info : public insn_call_clobbers_tree +{ + // Size 3 LP64 words. + friend class function_info; + +public: + // Return the next group in the list. + ebb_call_clobbers_info *next () const { return m_next; } + + // Return the function abi used by all the calls in the group. + const predefined_function_abi *abi () const { return m_abi; } + + // Return true if at least one call in the group should conservatively + // be assumed to clobber RESOURCE. + bool clobbers (resource_info) const; + + // Print a summary of what the class describes to PP, without printing + // the actual instructions. + void print_summary (pretty_printer *pp) const; + + // Print a full description of the object to PP, including the + // instructions it contains. + void print_full (pretty_printer *) const; + +private: + ebb_call_clobbers_info (const predefined_function_abi *); + + // The values returned by the accessors above. + ebb_call_clobbers_info *m_next; + const predefined_function_abi *m_abi; +}; + +// A list of ebb_call_clobbers_infos. +using ebb_call_clobbers_iterator + = list_iterator; + +// Information about an extended basic block. +// +// Each EBB has a list of phi nodes and starts with an artificial phi +// instruction that conceptually "executes" the phi nodes. The phi +// nodes are independent of one another and so can be executed in any +// order. The order of the phi nodes in the list is not significant. +// +// Each EBB also maintains a list of ebb_call_clobbers_info structures +// that describe all instructions for which has_call_clobbers () is true. +// See the comment above that class for details. +class ebb_info +{ + // Size: 5 LP64 words. + friend class function_info; + +public: + // Return the previous EBB in reverse postorder, or null if this EBB + // contains the entry block. + ebb_info *prev_ebb () const; + + // Return the next EBB in reverse postorder, or null if this EBB contains + // the exit block. + ebb_info *next_ebb () const; + + // Return the instruction that holds the EBB's phi nodes (and does + // nothing else). There is no associated RTL insn. + // + // This instruction always exists, even if the EBB does not currently + // need any phi nodes. + insn_info *phi_insn () const { return m_phi_insn; } + + // Return the first and last blocks in the EBB. + bb_info *first_bb () const { return m_first_bb; } + bb_info *last_bb () const { return m_last_bb; } + + // Return the first of the EBB's phi nodes. + phi_info *first_phi () const { return m_first_phi; } + + // Return the head of the list of ebb_call_clobbers_infos. + ebb_call_clobbers_info *first_call_clobbers () const; + + // Return the list of ebb_call_clobbers_infos. + iterator_range call_clobbers () const; + + // Return a list of the EBB's phi nodes, in arbitrary order. + iterator_range phis () const; + + // Return a list of the blocks in the EBB, in execution order. + iterator_range bbs () const; + + // Return a list of the blocks in the EBB, in reverse execution order. + iterator_range reverse_bbs () const; + + // Return a list of all the instructions in the EBB, in execution order. + // The list includes phi_insn (), the head and end of each block, + // and the real instructions in each block. + // + // Iterations over the list will pick up any new instructions that are + // inserted after the iterator's current instruction. + iterator_range all_insns () const; + + // Like all_insns (), except that the instructions are in reverse order. + // + // Iterations over the list will pick up any new instructions that are + // inserted before the iterator's current instruction. + iterator_range reverse_all_insns () const; + + // Like all_insns (), but without the debug instructions. + iterator_range nondebug_insns () const; + + // Like reverse_all_insns (), but without the debug instructions. + iterator_range + reverse_nondebug_insns () const; + + // Return an insn_range that covers the same instructions as all_insns (). + insn_range_info insn_range () const; + + // Print "ebb" + first_bb ()->index () to PP. + void print_identifier (pretty_printer *pp) const; + + // Print a full description of the EBB to PP. + void print_full (pretty_printer *pp) const; + +private: + ebb_info (bb_info *, bb_info *); + + void set_first_phi (phi_info *phi) { m_first_phi = phi; } + void set_phi_insn (insn_info *insn) { m_phi_insn = insn; } + void set_first_call_clobbers (ebb_call_clobbers_info *); + + // The values returned by the functions above. + phi_info *m_first_phi; + insn_info *m_phi_insn; + bb_info *m_first_bb; + bb_info *m_last_bb; + ebb_call_clobbers_info *m_first_call_clobbers; +}; + +// Iterators for lists of extended basic blocks. +using ebb_iterator = list_iterator; +using reverse_ebb_iterator = list_iterator; + +void pp_bb (pretty_printer *, const bb_info *); +void pp_ebb_call_clobbers (pretty_printer *, const ebb_call_clobbers_info *); +void pp_ebb (pretty_printer *, const ebb_info *); + +} + +void dump (FILE *, const rtl_ssa::bb_info *); +void dump (FILE *, const rtl_ssa::ebb_call_clobbers_info *); +void dump (FILE *, const rtl_ssa::ebb_info *); + +void DEBUG_FUNCTION debug (const rtl_ssa::bb_info *); +void DEBUG_FUNCTION debug (const rtl_ssa::ebb_call_clobbers_info *); +void DEBUG_FUNCTION debug (const rtl_ssa::ebb_info *); diff --git a/gcc/rtl-ssa/change-utils.h b/gcc/rtl-ssa/change-utils.h new file mode 100644 index 0000000..8245330 --- /dev/null +++ b/gcc/rtl-ssa/change-utils.h @@ -0,0 +1,137 @@ +// RTL SSA utility functions for changing instructions -*- C++ -*- +// Copyright (C) 2020 Free Software Foundation, Inc. +// +// This file is part of GCC. +// +// GCC is free software; you can redistribute it and/or modify it under +// the terms of the GNU General Public License as published by the Free +// Software Foundation; either version 3, or (at your option) any later +// version. +// +// GCC is distributed in the hope that it will be useful, but WITHOUT ANY +// WARRANTY; without even the implied warranty of MERCHANTABILITY or +// FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License +// for more details. +// +// You should have received a copy of the GNU General Public License +// along with GCC; see the file COPYING3. If not see +// . + +namespace rtl_ssa { + +// Return true if INSN is one of the instructions being changed by CHANGES. +inline bool +insn_is_changing (array_slice changes, + const insn_info *insn) +{ + for (const insn_change *change : changes) + if (change->insn () == insn) + return true; + return false; +} + +// Return a closure of insn_is_changing, for use as a predicate. +// This could be done using local lambdas instead, but the predicate is +// used often enough that having a class should be more convenient and allow +// reuse of template instantiations. +// +// We don't use std::bind because it would involve an indirect function call, +// whereas this function is used in relatively performance-critical code. +inline insn_is_changing_closure +insn_is_changing (array_slice changes) +{ + return insn_is_changing_closure (changes); +} + +// Restrict CHANGE.move_range so that the changed instruction can perform +// all its definitions and uses. Assume that if: +// +// - CHANGE contains an access A1 of resource R; +// - an instruction I2 contains another access A2 to R; and +// - IGNORE (I2) is true +// +// then either: +// +// - A2 will be removed; or +// - something will ensure that A1 and A2 maintain their current order, +// without this having to be enforced by CHANGE's move range. +// +// IGNORE should return true for CHANGE.insn (). +// +// Return true on success, otherwise leave CHANGE.move_range in an invalid +// state. +// +// This function only works correctly for instructions that remain within +// the same extended basic block. +template +bool +restrict_movement_ignoring (insn_change &change, IgnorePredicate ignore) +{ + // Uses generally lead to failure quicker, so test those first. + return (restrict_movement_for_uses_ignoring (change.move_range, + change.new_uses, ignore) + && restrict_movement_for_defs_ignoring (change.move_range, + change.new_defs, ignore) + && canonicalize_move_range (change.move_range, change.insn ())); +} + +// Like restrict_movement_ignoring, but ignore only the instruction +// that is being changed. +inline bool +restrict_movement (insn_change &change) +{ + return restrict_movement_ignoring (change, insn_is (change.insn ())); +} + +using add_regno_clobber_fn = std::function; +bool recog_internal (insn_change &, add_regno_clobber_fn); + +// Try to recognize the new instruction pattern for CHANGE, potentially +// tweaking the pattern or adding extra clobbers in order to make it match. +// +// When adding an extra clobber for register R, restrict CHANGE.move_range +// to a range of instructions for which R is not live. When determining +// whether R is live, ignore accesses made by an instruction I if +// IGNORE (I) is true. The caller then assumes the responsibility +// of ensuring that CHANGE and I are placed in a valid order. +// +// IGNORE should return true for CHANGE.insn (). +// +// Return true on success. Leave CHANGE unmodified on failure. +template +inline bool +recog_ignoring (obstack_watermark &watermark, insn_change &change, + IgnorePredicate ignore) +{ + auto add_regno_clobber = [&](insn_change &change, unsigned int regno) + { + return crtl->ssa->add_regno_clobber (watermark, change, regno, ignore); + }; + return recog_internal (change, add_regno_clobber); +} + +// As for recog_ignoring, but ignore only the instruction that is being +// changed. +inline bool +recog (obstack_watermark &watermark, insn_change &change) +{ + return recog_ignoring (watermark, change, insn_is (change.insn ())); +} + +// Check whether insn costs indicate that the net effect of the changes +// in CHANGES is worthwhile. Require a strict improvement if STRICT_P, +// otherwise allow the new instructions to be the same cost as the old +// instructions. +bool changes_are_worthwhile (array_slice changes, + bool strict_p = false); + +// Like changes_are_worthwhile, but for a single change. +inline bool +change_is_worthwhile (insn_change &change, bool strict_p = false) +{ + insn_change *changes[] = { &change }; + return changes_are_worthwhile (changes, strict_p); +} + +} diff --git a/gcc/rtl-ssa/changes.cc b/gcc/rtl-ssa/changes.cc new file mode 100644 index 0000000..1885a80 --- /dev/null +++ b/gcc/rtl-ssa/changes.cc @@ -0,0 +1,1025 @@ +// RTL SSA routines for changing instructions -*- C++ -*- +// Copyright (C) 2020 Free Software Foundation, Inc. +// +// This file is part of GCC. +// +// GCC is free software; you can redistribute it and/or modify it under +// the terms of the GNU General Public License as published by the Free +// Software Foundation; either version 3, or (at your option) any later +// version. +// +// GCC is distributed in the hope that it will be useful, but WITHOUT ANY +// WARRANTY; without even the implied warranty of MERCHANTABILITY or +// FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License +// for more details. +// +// You should have received a copy of the GNU General Public License +// along with GCC; see the file COPYING3. If not see +// . + +#define INCLUDE_ALGORITHM +#define INCLUDE_FUNCTIONAL +#include "config.h" +#include "system.h" +#include "coretypes.h" +#include "backend.h" +#include "rtl.h" +#include "df.h" +#include "rtl-ssa.h" +#include "rtl-ssa/internals.inl" +#include "target.h" +#include "predict.h" +#include "memmodel.h" // Needed by emit-rtl.h +#include "emit-rtl.h" +#include "cfghooks.h" +#include "cfgrtl.h" + +using namespace rtl_ssa; + +// See the comment above the declaration. +void +insn_change::print (pretty_printer *pp) const +{ + if (m_is_deletion) + { + pp_string (pp, "deletion of "); + pp_insn (pp, m_insn); + } + else + { + pp_string (pp, "change to "); + pp_insn (pp, m_insn); + pp_newline_and_indent (pp, 2); + pp_string (pp, "~~~~~~~"); + + pp_newline_and_indent (pp, 0); + pp_string (pp, "new cost: "); + pp_decimal_int (pp, new_cost); + + pp_newline_and_indent (pp, 0); + pp_string (pp, "new uses:"); + pp_newline_and_indent (pp, 2); + pp_accesses (pp, new_uses); + pp_indentation (pp) -= 2; + + pp_newline_and_indent (pp, 0); + pp_string (pp, "new defs:"); + pp_newline_and_indent (pp, 2); + pp_accesses (pp, new_defs); + pp_indentation (pp) -= 2; + + pp_newline_and_indent (pp, 0); + pp_string (pp, "first insert-after candidate: "); + move_range.first->print_identifier_and_location (pp); + + pp_newline_and_indent (pp, 0); + pp_string (pp, "last insert-after candidate: "); + move_range.last->print_identifier_and_location (pp); + } +} + +// Return a copy of access_array ACCESSES, allocating it on the +// temporary obstack. +access_array +function_info::temp_access_array (access_array accesses) +{ + if (accesses.empty ()) + return accesses; + + gcc_assert (obstack_object_size (&m_temp_obstack) == 0); + obstack_grow (&m_temp_obstack, accesses.begin (), accesses.size_bytes ()); + return { static_cast (obstack_finish (&m_temp_obstack)), + accesses.size () }; +} + +// See the comment above the declaration. +bool +function_info::verify_insn_changes (array_slice changes) +{ + HARD_REG_SET defined_hard_regs, clobbered_hard_regs; + CLEAR_HARD_REG_SET (defined_hard_regs); + CLEAR_HARD_REG_SET (clobbered_hard_regs); + + insn_info *min_insn = m_first_insn; + for (insn_change *change : changes) + if (!change->is_deletion ()) + { + // Make sure that the changes can be kept in their current order + // while honoring all of the move ranges. + min_insn = later_insn (min_insn, change->move_range.first); + while (min_insn != change->insn () && !can_insert_after (min_insn)) + min_insn = min_insn->next_nondebug_insn (); + if (*min_insn > *change->move_range.last) + { + if (dump_file && (dump_flags & TDF_DETAILS)) + fprintf (dump_file, "no viable insn position assignment\n"); + return false; + } + + // If recog introduced new clobbers of a register as part of + // the matching process, make sure that they don't conflict + // with any other new definitions or uses of the register. + // (We have already checked that they don't conflict with + // unchanging definitions and uses.) + for (use_info *use : change->new_uses) + { + unsigned int regno = use->regno (); + if (HARD_REGISTER_NUM_P (regno) + && TEST_HARD_REG_BIT (clobbered_hard_regs, regno)) + { + if (dump_file && (dump_flags & TDF_DETAILS)) + fprintf (dump_file, "register %d would be clobbered" + " while it is still live\n", regno); + return false; + } + } + for (def_info *def : change->new_defs) + { + unsigned int regno = def->regno (); + if (HARD_REGISTER_NUM_P (regno)) + { + if (def->m_is_temp) + { + // This is a clobber introduced by recog. + gcc_checking_assert (is_a (def)); + if (TEST_HARD_REG_BIT (defined_hard_regs, regno)) + { + if (dump_file && (dump_flags & TDF_DETAILS)) + fprintf (dump_file, "conflicting definitions of" + " register %d\n", regno); + return false; + } + SET_HARD_REG_BIT (clobbered_hard_regs, regno); + } + else if (is_a (def)) + { + // REGNO now has a defined value. + SET_HARD_REG_BIT (defined_hard_regs, regno); + CLEAR_HARD_REG_BIT (clobbered_hard_regs, regno); + } + } + } + } + return true; +} + +// See the comment above the declaration. +bool +rtl_ssa::changes_are_worthwhile (array_slice changes, + bool strict_p) +{ + unsigned int old_cost = 0; + unsigned int new_cost = 0; + for (insn_change *change : changes) + { + old_cost += change->old_cost (); + if (!change->is_deletion ()) + { + basic_block cfg_bb = change->bb ()->cfg_bb (); + change->new_cost = insn_cost (change->rtl (), + optimize_bb_for_speed_p (cfg_bb)); + new_cost += change->new_cost; + } + } + bool ok_p = (strict_p ? new_cost < old_cost : new_cost <= old_cost); + if (dump_file && (dump_flags & TDF_DETAILS)) + { + fprintf (dump_file, "original cost"); + char sep = '='; + for (const insn_change *change : changes) + { + fprintf (dump_file, " %c %d", sep, change->old_cost ()); + sep = '+'; + } + fprintf (dump_file, ", replacement cost"); + sep = '='; + for (const insn_change *change : changes) + if (!change->is_deletion ()) + { + fprintf (dump_file, " %c %d", sep, change->new_cost); + sep = '+'; + } + fprintf (dump_file, "; %s\n", + ok_p ? "keeping replacement" : "rejecting replacement"); + } + if (!ok_p) + return false; + + return true; +} + +// Update the REG_NOTES of INSN, whose pattern has just been changed. +static void +update_notes (rtx_insn *insn) +{ + for (rtx *note_ptr = ®_NOTES (insn); *note_ptr; ) + { + rtx note = *note_ptr; + bool keep_p = true; + switch (REG_NOTE_KIND (note)) + { + case REG_EQUAL: + case REG_EQUIV: + case REG_NOALIAS: + keep_p = (single_set (insn) != nullptr); + break; + + case REG_UNUSED: + case REG_DEAD: + // These notes are stale. We'll recompute REG_UNUSED notes + // after the update. + keep_p = false; + break; + + default: + break; + } + if (keep_p) + note_ptr = &XEXP (*note_ptr, 1); + else + { + *note_ptr = XEXP (*note_ptr, 1); + free_EXPR_LIST_node (note); + } + } +} + +// Pick a location for CHANGE's instruction and return the instruction +// after which it should be placed. +static insn_info * +choose_insn_placement (insn_change &change) +{ + gcc_checking_assert (change.move_range); + + insn_info *insn = change.insn (); + insn_info *first = change.move_range.first; + insn_info *last = change.move_range.last; + + // Quick(ish) exit if there is only one possible choice. + if (first == last) + return first; + if (first == insn->prev_nondebug_insn () && last == insn) + return insn; + + // For now just use the closest valid choice to the original instruction. + // If the register usage has changed significantly, it might instead be + // better to try to take register pressure into account. + insn_info *closest = change.move_range.clamp_insn_to_range (insn); + while (closest != insn && !can_insert_after (closest)) + closest = closest->next_nondebug_insn (); + return closest; +} + +// Record any changes related to CHANGE that need to be queued for later. +void +function_info::possibly_queue_changes (insn_change &change) +{ + insn_info *insn = change.insn (); + rtx_insn *rtl = insn->rtl (); + + // If the instruction could previously throw, we eventually need to call + // purge_dead_edges to check whether things have changed. + if (find_reg_note (rtl, REG_EH_REGION, nullptr)) + bitmap_set_bit (m_need_to_purge_dead_edges, insn->bb ()->index ()); + + auto needs_pending_update = [&]() + { + // If an instruction became a no-op without the pass explicitly + // deleting it, queue the deletion for later. Removing the + // instruction on the fly would require an update to all instructions + // that use the result of the move, which would be a potential source + // of quadraticness. Also, definitions shouldn't disappear under + // the pass's feet. + if (INSN_CODE (rtl) == NOOP_MOVE_INSN_CODE) + return true; + + // If any jumps got turned into unconditional jumps or nops, we need + // to update the CFG accordingly. + if (JUMP_P (rtl) + && (returnjump_p (rtl) || any_uncondjump_p (rtl)) + && !single_succ_p (insn->bb ()->cfg_bb ())) + return true; + + // If a previously conditional trap now always fires, execution + // terminates at that point. + rtx pattern = PATTERN (rtl); + if (GET_CODE (pattern) == TRAP_IF + && XEXP (pattern, 0) == const1_rtx) + return true; + + return false; + }; + + if (needs_pending_update () + && bitmap_set_bit (m_queued_insn_update_uids, insn->uid ())) + { + gcc_assert (!change.is_deletion ()); + m_queued_insn_updates.safe_push (insn); + } +} + +// Remove the instruction described by CHANGE from the underlying RTL +// and from the insn_info list. +static void +delete_insn (insn_change &change) +{ + insn_info *insn = change.insn (); + rtx_insn *rtl = change.rtl (); + if (dump_file && (dump_flags & TDF_DETAILS)) + fprintf (dump_file, "deleting insn %d\n", insn->uid ()); + set_insn_deleted (rtl); +} + +// Move the RTL instruction associated with CHANGE so that it comes +// immediately after AFTER. +static void +move_insn (insn_change &change, insn_info *after) +{ + rtx_insn *rtl = change.rtl (); + rtx_insn *after_rtl = after->rtl (); + if (dump_file && (dump_flags & TDF_DETAILS)) + fprintf (dump_file, "moving insn %d after insn %d\n", + INSN_UID (rtl), INSN_UID (after_rtl)); + + // At the moment we don't support moving instructions between EBBs, + // but this would be worth adding if it's useful. + insn_info *insn = change.insn (); + gcc_assert (after->ebb () == insn->ebb ()); + bb_info *bb = after->bb (); + basic_block cfg_bb = bb->cfg_bb (); + + if (insn->bb () != bb) + // Force DF to mark the old block as dirty. + df_insn_delete (rtl); + ::remove_insn (rtl); + ::add_insn_after (rtl, after_rtl, cfg_bb); +} + +// The instruction associated with CHANGE is being changed in-place. +// Update the DF information for its new pattern. +static void +update_insn_in_place (insn_change &change) +{ + insn_info *insn = change.insn (); + if (dump_file && (dump_flags & TDF_DETAILS)) + fprintf (dump_file, "updating insn %d in-place\n", insn->uid ()); + df_insn_rescan (change.rtl ()); +} + +// Finalize the new list of definitions and uses in CHANGE, removing +// any uses and definitions that are no longer needed, and converting +// pending clobbers into actual definitions. +void +function_info::finalize_new_accesses (insn_change &change) +{ + insn_info *insn = change.insn (); + + // Get a list of all the things that the instruction now references. + vec_rtx_properties properties; + properties.add_insn (insn->rtl (), true); + + // Build up the new list of definitions. + for (rtx_obj_reference ref : properties.refs ()) + if (ref.is_write ()) + { + def_info *def = find_access (change.new_defs, ref.regno); + gcc_assert (def); + if (def->m_is_temp) + { + // At present, the only temporary instruction definitions we + // create are clobbers, such as those added during recog. + gcc_assert (is_a (def)); + def = allocate (change.insn (), ref.regno); + } + else if (!def->m_has_been_superceded) + { + // This is a second or subsequent definition. + // See function_info::record_def for a discussion of when + // this can happen. + def->record_reference (ref, false); + continue; + } + else + { + def->m_has_been_superceded = false; + + // Clobbers can move around, so remove them from their current + // position and them back in their final position. + // + // At the moment, we don't allow sets to move relative to other + // definitions of the same resource, so we can leave those where + // they are. It might be useful to relax this in future. + // The main complication is that removing a set would potentially + // fuse two adjoining clobber_groups, and adding the set back + // would require the group to be split again. + if (is_a (def)) + remove_def (def); + else if (ref.is_reg ()) + def->set_mode (ref.mode); + def->set_insn (insn); + } + def->record_reference (ref, true); + m_temp_defs.safe_push (def); + } + + // Also keep any explicitly-recorded call clobbers, which are deliberately + // excluded from the vec_rtx_properties. + for (def_info *def : change.new_defs) + if (def->m_has_been_superceded && def->is_call_clobber ()) + { + def->m_has_been_superceded = false; + def->set_insn (insn); + m_temp_defs.safe_push (def); + } + + // Install the new list of definitions in CHANGE. + sort_accesses (m_temp_defs); + access_array accesses = temp_access_array (m_temp_defs); + change.new_defs = def_array (accesses); + m_temp_defs.truncate (0); + + // Create temporary copies of use_infos that are already attached to + // other insns, which could happen if the uses come from unchanging + // insns or if they have been used by earlier changes. Doing this + // makes it easier to detect multiple reads below. + auto *unshared_uses_base = XOBNEWVEC (&m_temp_obstack, access_info *, + change.new_uses.size ()); + unsigned int i = 0; + for (use_info *use : change.new_uses) + { + if (!use->m_has_been_superceded) + { + use = allocate_temp (insn, use->resource (), use->def ()); + use->m_has_been_superceded = true; + use->m_is_temp = true; + } + unshared_uses_base[i++] = use; + } + auto unshared_uses = use_array (unshared_uses_base, change.new_uses.size ()); + + // Add (possibly temporary) uses to m_temp_uses for each resource. + // If there are multiple references to the same resource, aggregate + // information in the modes and flags. + for (rtx_obj_reference ref : properties.refs ()) + if (ref.is_read ()) + { + unsigned int regno = ref.regno; + machine_mode mode = ref.is_reg () ? ref.mode : BLKmode; + use_info *use = find_access (unshared_uses, ref.regno); + gcc_assert (use); + if (use->m_has_been_superceded) + { + // This is the first reference to the resource. + bool is_temp = use->m_is_temp; + *use = use_info (insn, resource_info { mode, regno }, use->def ()); + use->m_is_temp = is_temp; + use->record_reference (ref, true); + m_temp_uses.safe_push (use); + } + else + { + // Record the mode of the largest use. The choice is arbitrary if + // the instruction (unusually) references the same register in two + // different but equal-sized modes. + if (HARD_REGISTER_NUM_P (regno) + && partial_subreg_p (use->mode (), mode)) + use->set_mode (mode); + use->record_reference (ref, false); + } + } + + // Replace any temporary uses and definitions with real ones. + for (unsigned int i = 0; i < m_temp_uses.length (); ++i) + { + auto *use = as_a (m_temp_uses[i]); + if (use->m_is_temp) + { + m_temp_uses[i] = use = allocate (*use); + use->m_is_temp = false; + set_info *def = use->def (); + // Handle cases in which the value was previously not used + // within the block. + if (def && def->m_is_temp) + { + phi_info *phi = as_a (def); + gcc_assert (phi->is_degenerate ()); + phi = create_degenerate_phi (phi->ebb (), phi->input_value (0)); + use->set_def (phi); + } + } + } + + // Install the new list of definitions in CHANGE. + sort_accesses (m_temp_uses); + change.new_uses = use_array (temp_access_array (m_temp_uses)); + m_temp_uses.truncate (0); + + // Record the new instruction-wide properties. + insn->set_properties (properties); +} + +// Copy information from CHANGE to its underlying insn_info, given that +// the insn_info has already been placed appropriately. +void +function_info::apply_changes_to_insn (insn_change &change) +{ + insn_info *insn = change.insn (); + if (change.is_deletion ()) + { + insn->set_accesses (nullptr, 0, 0); + return; + } + + // Copy the cost. + insn->set_cost (change.new_cost); + + // Add all clobbers. Sets never moved relative to other definitions, + // so are OK as-is. + for (def_info *def : change.new_defs) + if (is_a (def)) + add_def (def); + + // Add all uses, now that their position is final. + for (use_info *use : change.new_uses) + add_use (use); + + // Copy the uses and definitions. + unsigned int num_defs = change.new_defs.size (); + unsigned int num_uses = change.new_uses.size (); + if (num_defs + num_uses <= insn->num_defs () + insn->num_uses ()) + insn->copy_accesses (change.new_defs, change.new_uses); + else + { + access_array_builder builder (&m_obstack); + builder.reserve (num_defs + num_uses); + + for (def_info *def : change.new_defs) + builder.quick_push (def); + for (use_info *use : change.new_uses) + builder.quick_push (use); + + insn->set_accesses (builder.finish ().begin (), num_defs, num_uses); + } + + add_reg_unused_notes (insn); +} + +// Add a temporary placeholder instruction after AFTER. +insn_info * +function_info::add_placeholder_after (insn_info *after) +{ + insn_info *insn = allocate_temp (after->bb (), nullptr, -1); + add_insn_after (insn, after); + return insn; +} + +// See the comment above the declaration. +void +function_info::change_insns (array_slice changes) +{ + auto watermark = temp_watermark (); + + insn_info *min_insn = m_first_insn; + for (insn_change *change : changes) + { + // Tentatively mark all the old uses and definitions for deletion. + for (use_info *use : change->old_uses ()) + { + use->m_has_been_superceded = true; + remove_use (use); + } + for (def_info *def : change->old_defs ()) + def->m_has_been_superceded = true; + + if (!change->is_deletion ()) + { + // Remove any notes that are no longer relevant. + update_notes (change->rtl ()); + + // Make sure that the placement of this instruction would still + // leave room for previous instructions. + change->move_range = move_later_than (change->move_range, min_insn); + if (!canonicalize_move_range (change->move_range, change->insn ())) + // verify_insn_changes is supposed to make sure that this holds. + gcc_unreachable (); + min_insn = later_insn (min_insn, change->move_range.first); + } + } + + // Walk backwards through the changes, allocating specific positions + // to each one. Update the underlying RTL and its associated DF + // information. + insn_info *following_insn = nullptr; + auto_vec placeholders; + placeholders.safe_grow_cleared (changes.size ()); + for (unsigned int i = changes.size (); i-- > 0;) + { + insn_change &change = *changes[i]; + insn_info *placeholder = nullptr; + possibly_queue_changes (change); + if (change.is_deletion ()) + delete_insn (change); + else + { + // Make sure that this instruction comes before later ones. + if (following_insn) + { + change.move_range = move_earlier_than (change.move_range, + following_insn); + if (!canonicalize_move_range (change.move_range, + change.insn ())) + // verify_insn_changes is supposed to make sure that this + // holds. + gcc_unreachable (); + } + + // Decide which instruction INSN should go after. + insn_info *after = choose_insn_placement (change); + + // If INSN is moving, insert a placeholder insn_info at the + // new location. We can't move INSN itself yet because it + // might still be referenced by earlier move ranges. + insn_info *insn = change.insn (); + if (after == insn || after == insn->prev_nondebug_insn ()) + { + update_insn_in_place (change); + following_insn = insn; + } + else + { + move_insn (change, after); + placeholder = add_placeholder_after (after); + following_insn = placeholder; + } + + // Finalize the new list of accesses for the change. Don't install + // them yet, so that we still have access to the old lists below. + finalize_new_accesses (change); + } + placeholders[i] = placeholder; + } + + // Remove all definitions that are no longer needed. After the above, + // such definitions should no longer have any registered users. + // + // In particular, this means that consumers must handle debug + // instructions before removing a set. + for (insn_change *change : changes) + for (def_info *def : change->old_defs ()) + if (def->m_has_been_superceded) + { + auto *set = dyn_cast (def); + gcc_assert (!set || !set->has_any_uses ()); + remove_def (def); + } + + // Move the insn_infos to their new locations. + for (unsigned int i = 0; i < changes.size (); ++i) + { + insn_change &change = *changes[i]; + insn_info *insn = change.insn (); + if (change.is_deletion ()) + remove_insn (insn); + else if (insn_info *placeholder = placeholders[i]) + { + // Check if earlier movements turned a move into a no-op. + if (placeholder->prev_nondebug_insn () == insn + || placeholder->next_nondebug_insn () == insn) + { + remove_insn (placeholder); + placeholders[i] = nullptr; + } + else + { + // Remove the placeholder first so that we have a wider range of + // program points when inserting INSN. + insn_info *after = placeholder->prev_any_insn (); + remove_insn (insn); + remove_insn (placeholder); + insn->set_bb (after->bb ()); + add_insn_after (insn, after); + } + } + } + + // Finally apply the changes to the underlying insn_infos. + for (insn_change *change : changes) + apply_changes_to_insn (*change); +} + +// See the comment above the declaration. +void +function_info::change_insn (insn_change &change) +{ + insn_change *changes[] = { &change }; + return change_insns (changes); +} + +// Try to adjust CHANGE so that its pattern can include clobber rtx CLOBBER. +// Return true on success. +// +// ADD_REGNO_CLOBBER is a specialization of function_info::add_regno_clobber +// for a specific caller-provided predicate. +static bool +add_clobber (insn_change &change, add_regno_clobber_fn add_regno_clobber, + rtx clobber) +{ + rtx pat = PATTERN (change.rtl ()); + gcc_assert (GET_CODE (clobber) == CLOBBER); + rtx dest = XEXP (clobber, 0); + if (GET_CODE (dest) == SCRATCH) + { + if (reload_completed) + { + if (dump_file && (dump_flags & TDF_DETAILS)) + { + // ??? Maybe we could try to do some RA here? + fprintf (dump_file, "instruction requires a scratch" + " after reload:\n"); + print_rtl_single (dump_file, pat); + } + return false; + } + return true; + } + + gcc_assert (REG_P (dest)); + for (unsigned int regno = REGNO (dest); regno != END_REGNO (dest); ++regno) + if (!add_regno_clobber (change, regno)) + { + if (dump_file && (dump_flags & TDF_DETAILS)) + { + fprintf (dump_file, "cannot clobber live register %d in:\n", + regno); + print_rtl_single (dump_file, pat); + } + return false; + } + return true; +} + +// Try to recognize the new form of the insn associated with CHANGE, +// adding any clobbers that are necessary to make the instruction match +// an .md pattern. Return true on success. +// +// ADD_REGNO_CLOBBER is a specialization of function_info::add_regno_clobber +// for a specific caller-provided predicate. +static bool +recog_level2 (insn_change &change, add_regno_clobber_fn add_regno_clobber) +{ + insn_change_watermark insn_watermark; + rtx_insn *rtl = change.rtl (); + rtx pat = PATTERN (rtl); + int num_clobbers = 0; + int icode = -1; + bool asm_p = asm_noperands (pat) >= 0; + if (asm_p) + { + if (!check_asm_operands (pat)) + { + if (dump_file && (dump_flags & TDF_DETAILS)) + { + fprintf (dump_file, "failed to match this asm instruction:\n"); + print_rtl_single (dump_file, pat); + } + return false; + } + } + else if (noop_move_p (rtl)) + { + INSN_CODE (rtl) = NOOP_MOVE_INSN_CODE; + if (dump_file && (dump_flags & TDF_DETAILS)) + { + fprintf (dump_file, "instruction becomes a no-op:\n"); + print_rtl_single (dump_file, pat); + } + insn_watermark.keep (); + return true; + } + else + { + icode = ::recog (pat, rtl, &num_clobbers); + if (icode < 0) + { + if (dump_file && (dump_flags & TDF_DETAILS)) + { + fprintf (dump_file, "failed to match this instruction:\n"); + print_rtl_single (dump_file, pat); + } + return false; + } + } + + auto prev_new_defs = change.new_defs; + auto prev_move_range = change.move_range; + if (num_clobbers > 0) + { + // ??? It would be good to have a way of recycling the rtxes on failure, + // but any attempt to cache old PARALLELs would at best be a half + // measure, since add_clobbers would still generate fresh clobbers + // each time. It would be better to have a more general recycling + // mechanism that all rtx passes can use. + rtvec newvec; + int oldlen; + if (GET_CODE (pat) == PARALLEL) + { + oldlen = XVECLEN (pat, 0); + newvec = rtvec_alloc (num_clobbers + oldlen); + for (int i = 0; i < oldlen; ++i) + RTVEC_ELT (newvec, i) = XVECEXP (pat, 0, i); + } + else + { + oldlen = 1; + newvec = rtvec_alloc (num_clobbers + oldlen); + RTVEC_ELT (newvec, 0) = pat; + } + rtx newpat = gen_rtx_PARALLEL (VOIDmode, newvec); + add_clobbers (newpat, icode); + validate_change (rtl, &PATTERN (rtl), newpat, true); + for (int i = 0; i < num_clobbers; ++i) + if (!add_clobber (change, add_regno_clobber, + XVECEXP (newpat, 0, oldlen + i))) + { + change.new_defs = prev_new_defs; + change.move_range = prev_move_range; + return false; + } + + pat = newpat; + } + + INSN_CODE (rtl) = icode; + if (reload_completed) + { + extract_insn (rtl); + if (!constrain_operands (1, get_preferred_alternatives (rtl))) + { + if (dump_file && (dump_flags & TDF_DETAILS)) + { + if (asm_p) + fprintf (dump_file, "asm does not match its constraints:\n"); + else if (const char *name = get_insn_name (icode)) + fprintf (dump_file, "instruction does not match the" + " constraints for %s:\n", name); + else + fprintf (dump_file, "instruction does not match its" + " constraints:\n"); + print_rtl_single (dump_file, pat); + } + change.new_defs = prev_new_defs; + change.move_range = prev_move_range; + return false; + } + } + + if (dump_file && (dump_flags & TDF_DETAILS)) + { + const char *name; + if (!asm_p && (name = get_insn_name (icode))) + fprintf (dump_file, "successfully matched this instruction " + "to %s:\n", name); + else + fprintf (dump_file, "successfully matched this instruction:\n"); + print_rtl_single (dump_file, pat); + } + + insn_watermark.keep (); + return true; +} + +// Try to recognize the new form of the insn associated with CHANGE, +// adding and removing clobbers as necessary to make the instruction +// match an .md pattern. Return true on success, otherwise leave +// CHANGE as it was on entry. +// +// ADD_REGNO_CLOBBER is a specialization of function_info::add_regno_clobber +// for a specific caller-provided predicate. +bool +rtl_ssa::recog_internal (insn_change &change, + add_regno_clobber_fn add_regno_clobber) +{ + // Accept all changes to debug instructions. + insn_info *insn = change.insn (); + if (insn->is_debug_insn ()) + return true; + + rtx_insn *rtl = insn->rtl (); + rtx pat = PATTERN (rtl); + if (GET_CODE (pat) == PARALLEL && asm_noperands (pat) < 0) + { + // Try to remove trailing (clobber (scratch)) rtxes, since the new form + // of the instruction might not need those scratches. recog will add + // back any that are needed. + int len = XVECLEN (pat, 0); + int new_len = len; + while (new_len > 0 + && GET_CODE (XVECEXP (pat, 0, new_len - 1)) == CLOBBER + && GET_CODE (XEXP (XVECEXP (pat, 0, new_len - 1), 0)) == SCRATCH) + new_len -= 1; + + int old_num_changes = num_validated_changes (); + validate_change_xveclen (rtl, &PATTERN (rtl), new_len, true); + if (recog_level2 (change, add_regno_clobber)) + return true; + cancel_changes (old_num_changes); + + // Try to remove all trailing clobbers. For example, a pattern that + // used to clobber the flags might no longer need to do so. + int prev_len = new_len; + while (new_len > 0 + && GET_CODE (XVECEXP (pat, 0, new_len - 1)) == CLOBBER) + new_len -= 1; + if (new_len != prev_len) + { + validate_change_xveclen (rtl, &PATTERN (rtl), new_len, true); + if (recog_level2 (change, add_regno_clobber)) + return true; + cancel_changes (old_num_changes); + } + return false; + } + + return recog_level2 (change, add_regno_clobber); +} + +// See the comment above the declaration. +bool +function_info::perform_pending_updates () +{ + bool changed_cfg = false; + bool changed_jumps = false; + for (insn_info *insn : m_queued_insn_updates) + { + rtx_insn *rtl = insn->rtl (); + if (JUMP_P (rtl)) + { + if (INSN_CODE (rtl) == NOOP_MOVE_INSN_CODE) + { + ::delete_insn (rtl); + bitmap_set_bit (m_need_to_purge_dead_edges, + insn->bb ()->index ()); + } + else if (returnjump_p (rtl) || any_uncondjump_p (rtl)) + { + mark_jump_label (PATTERN (rtl), rtl, 0); + update_cfg_for_uncondjump (rtl); + changed_cfg = true; + changed_jumps = true; + } + } + else if (INSN_CODE (rtl) == NOOP_MOVE_INSN_CODE) + ::delete_insn (rtl); + else + { + rtx pattern = PATTERN (rtl); + if (GET_CODE (pattern) == TRAP_IF + && XEXP (pattern, 0) == const1_rtx) + { + remove_edge (split_block (BLOCK_FOR_INSN (rtl), rtl)); + emit_barrier_after_bb (BLOCK_FOR_INSN (rtl)); + changed_cfg = true; + } + } + } + + unsigned int index; + bitmap_iterator bi; + EXECUTE_IF_SET_IN_BITMAP (m_need_to_purge_dead_edges, 0, index, bi) + if (purge_dead_edges (BASIC_BLOCK_FOR_FN (m_fn, index))) + changed_cfg = true; + + if (changed_jumps) + // This uses its own timevar internally, so we don't need to push + // one ourselves. + rebuild_jump_labels (get_insns ()); + + bitmap_clear (m_need_to_purge_dead_edges); + bitmap_clear (m_queued_insn_update_uids); + m_queued_insn_updates.truncate (0); + + if (changed_cfg) + { + free_dominance_info (CDI_DOMINATORS); + free_dominance_info (CDI_POST_DOMINATORS); + } + + return changed_cfg; +} + +// Print a description of CHANGE to PP. +void +rtl_ssa::pp_insn_change (pretty_printer *pp, const insn_change &change) +{ + change.print (pp); +} + +// Print a description of CHANGE to FILE. +void +dump (FILE *file, const insn_change &change) +{ + dump_using (file, pp_insn_change, change); +} + +// Debug interface to the dump routine above. +void debug (const insn_change &x) { dump (stderr, x); } diff --git a/gcc/rtl-ssa/changes.h b/gcc/rtl-ssa/changes.h new file mode 100644 index 0000000..308c5ed --- /dev/null +++ b/gcc/rtl-ssa/changes.h @@ -0,0 +1,118 @@ +// RTL SSA classes related to changing instructions -*- C++ -*- +// Copyright (C) 2020 Free Software Foundation, Inc. +// +// This file is part of GCC. +// +// GCC is free software; you can redistribute it and/or modify it under +// the terms of the GNU General Public License as published by the Free +// Software Foundation; either version 3, or (at your option) any later +// version. +// +// GCC is distributed in the hope that it will be useful, but WITHOUT ANY +// WARRANTY; without even the implied warranty of MERCHANTABILITY or +// FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License +// for more details. +// +// You should have received a copy of the GNU General Public License +// along with GCC; see the file COPYING3. If not see +// . + +namespace rtl_ssa { + +// A class that describes a change that we're considering making to an +// instruction. There are three choices: +// +// (1) delete the instruction +// (2) replace the instruction with a new instruction in-place +// (3) replace the instruction with a new instruction at a different location +// +// Anything related to the "new instruction" is irrelevant for (1). +// +// The class doesn't actually change anything itself, it simply records +// something that we might do. +class insn_change +{ +public: + enum delete_action { DELETE }; + + // Construct a possible change to INSN. + insn_change (insn_info *insn); + + // Construct a possible deletion of INSN. + insn_change (insn_info *insn, delete_action); + + // The instruction that we would change. + insn_info *insn () const { return m_insn; } + + // The rtx_insn of the instruction that we would change. + rtx_insn *rtl () const { return m_insn->rtl (); } + + // The basic block that contains insn (). + bb_info *bb () const { return m_insn->bb (); } + + // The extended basic block that contains insn (). + ebb_info *ebb () const { return m_insn->ebb (); } + + // The uid of the instruction that we would change. + unsigned int insn_uid () const { return m_insn->uid (); } + + // The list of things that the original instruction defined and used. + def_array old_defs () const { return m_insn->defs (); } + use_array old_uses () const { return m_insn->uses (); } + + // The cost of the original instruction, as calculated by the target. + unsigned int old_cost () const { return m_insn->cost (); } + + // Return true if the original instruction would simply be deleted, + // rather than being replaced by a new instruction. + bool is_deletion () const { return m_is_deletion; } + + // Print a description of the change to PP. + void print (pretty_printer *pp) const; + + // Return an insn_change for deleting INSN. + static insn_change delete_insn (insn_info *insn) { return { insn, DELETE }; } + +private: + // The value returned by insn (). + insn_info *m_insn; + +public: + // The list of things that the new instruction would define and use. + def_array new_defs; + use_array new_uses; + + // The range of instructions after which the instruction could be placed. + // The range can include INSN itself: placing the instruction after either + // INSN or INSN->prev_nondebug_insn () is equivalent to not moving the + // instruction. + insn_range_info move_range; + + // The cost that the new instruction would have, as calculated by the target. + unsigned int new_cost; + +private: + // The value returned by is_deletion (). + bool m_is_deletion; +}; + +// A class that represents a closure of the two-argument form of +// insn_is_changing. See the comment above the one-argument form +// for details. +class insn_is_changing_closure +{ +public: + insn_is_changing_closure (array_slice changes); + bool operator() (const insn_info *) const; + +private: + array_slice m_changes; +}; + +void pp_insn_change (pretty_printer *, const insn_change &); + +} + +void dump (FILE *, const rtl_ssa::insn_change &); + +void DEBUG_FUNCTION debug (const rtl_ssa::insn_change &); diff --git a/gcc/rtl-ssa/functions.cc b/gcc/rtl-ssa/functions.cc new file mode 100644 index 0000000..50595ac --- /dev/null +++ b/gcc/rtl-ssa/functions.cc @@ -0,0 +1,325 @@ +// Implementation of function-related RTL SSA functions -*- C++ -*- +// Copyright (C) 2020 Free Software Foundation, Inc. +// +// This file is part of GCC. +// +// GCC is free software; you can redistribute it and/or modify it under +// the terms of the GNU General Public License as published by the Free +// Software Foundation; either version 3, or (at your option) any later +// version. +// +// GCC is distributed in the hope that it will be useful, but WITHOUT ANY +// WARRANTY; without even the implied warranty of MERCHANTABILITY or +// FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License +// for more details. +// +// You should have received a copy of the GNU General Public License +// along with GCC; see the file COPYING3. If not see +// . + +#define INCLUDE_ALGORITHM +#define INCLUDE_FUNCTIONAL +#include "config.h" +#include "system.h" +#include "coretypes.h" +#include "backend.h" +#include "rtl.h" +#include "df.h" +#include "rtl-ssa.h" +#include "rtl-ssa/internals.inl" + +using namespace rtl_ssa; + +function_info::function_info (function *fn) + : m_fn (fn) +{ + // Force the alignment to be obstack_alignment. Everything else is normal. + obstack_specify_allocation (&m_obstack, OBSTACK_CHUNK_SIZE, + obstack_alignment, obstack_chunk_alloc, + obstack_chunk_free); + obstack_specify_allocation (&m_temp_obstack, OBSTACK_CHUNK_SIZE, + obstack_alignment, obstack_chunk_alloc, + obstack_chunk_free); + + // Record the start of the obstacks. + m_obstack_start = XOBNEWVAR (&m_obstack, char, 0); + m_temp_obstack_start = XOBNEWVAR (&m_temp_obstack, char, 0); + + init_function_data (); + process_all_blocks (); + simplify_phis (); +} + +function_info::~function_info () +{ + // Anything using the temporary obstack should free it afterwards, + // preferably via temp_watermark (). + gcc_assert (XOBNEWVAR (&m_temp_obstack, char, 0) == m_temp_obstack_start); + + obstack_free (&m_temp_obstack, nullptr); + obstack_free (&m_obstack, nullptr); +} + +// See the comment above the declaration. +void +function_info::print (pretty_printer *pp) const +{ + pp_string (pp, "Function: "); + pp_string (pp, function_name (m_fn)); + for (ebb_info *ebb : ebbs ()) + { + pp_newline (pp); + pp_newline_and_indent (pp, 0); + pp_ebb (pp, ebb); + } +} + +// Calculate m_potential_phi_regs. +void +function_info::calculate_potential_phi_regs () +{ + auto *lr_info = DF_LR_BB_INFO (ENTRY_BLOCK_PTR_FOR_FN (m_fn)); + for (unsigned int regno = 0; regno < m_num_regs; ++regno) + if (regno >= DF_REG_SIZE (DF) + // Exclude registers that have a single definition that dominates + // all uses. If the definition does not dominate all uses, + // the register will be exposed upwards to the entry block but + // will not be defined by the entry block. + || DF_REG_DEF_COUNT (regno) > 1 + || (!bitmap_bit_p (&lr_info->def, regno) + && bitmap_bit_p (&lr_info->out, regno))) + bitmap_set_bit (m_potential_phi_regs, regno); +} + +// Initialize all member variables in preparation for (re)building +// SSA form from scratch. +void +function_info::init_function_data () +{ + m_next_artificial_uid = -1; + m_next_phi_uid = 0; + m_num_regs = max_reg_num (); + m_defs.safe_grow_cleared (m_num_regs + 1); + m_bbs.safe_grow_cleared (last_basic_block_for_fn (m_fn)); + m_first_bb = nullptr; + m_last_bb = nullptr; + m_first_insn = nullptr; + m_last_insn = nullptr; + m_last_nondebug_insn = nullptr; + m_free_phis = nullptr; + + calculate_potential_phi_regs (); +} + +// The initial phase of the phi simplification process. The cumulative +// effect of the initial phase is to set up ASSUMED_VALUES such that, +// for a phi P with uid ID: +// +// - if we think all inputs to P have the same value, ASSUMED_VALUES[ID] +// is that value +// +// - otherwise, ASSUMED_VALUES[ID] is P. +// +// This has already been done for phis with a lower uid than PHI, +// initially making optimistic assumptions about backedge inputs. +// Now do the same for PHI. If this might invalidate any assumptions +// made for earlier phis, add the uids of those phis to WORKLIST. +void +function_info::simplify_phi_setup (phi_info *phi, set_info **assumed_values, + bitmap worklist) +{ + // If all non-backedge inputs have the same value, set NEW_VALUE + // to that value. Otherwise set NEW_VALUE to PHI, to indicate + // that PHI cannot be simplified. + unsigned int phi_uid = phi->uid (); + bool is_first_input = true; + set_info *new_value = nullptr; + machine_mode phi_mode = phi->mode (); + for (use_info *input : phi->inputs ()) + { + set_info *def = input->def (); + + if (auto *input_phi = safe_dyn_cast (def)) + { + // Ignore backedges for now. + unsigned int input_phi_uid = input_phi->uid (); + if (phi_uid <= input_phi_uid) + continue; + + def = assumed_values[input_phi_uid]; + } + + // Compare this definition with previous ones. + if (is_first_input) + { + new_value = def; + is_first_input = false; + } + else if (new_value != def) + new_value = phi; + + // If the input has a known mode (i.e. not BLKmode), make sure + // that the phi's mode is at least as large. + if (def) + phi_mode = combine_modes (phi_mode, def->mode ()); + } + if (phi->mode () != phi_mode) + phi->set_mode (phi_mode); + + // Since we use a reverse postorder traversal, no phi can consist + // entirely of backedges. + gcc_checking_assert (!is_first_input); + assumed_values[phi_uid] = new_value; + + // See whether any assumptions for earlier phis are now invalid. + simplify_phi_propagate (phi, assumed_values, nullptr, worklist); +} + +// The propagation phase of the phi simplification process, with +// ASSUMED_VALUES as described above simplify_phi_setup. Iteratively +// update the phis that use PHI based on PHI's entry in ASSUMED_VALUES. +// If CURR_WORKLIST is null, consider only phi uses with a lower uid +// than PHI, otherwise consider all phi uses. +// +// If a phi with a higher uid than PHI needs updating, add its uid to +// CURR_WORKLIST; if a phi with a lower uid than PHI needs updating, +// add its uid to NEXT_WORKLIST. +void +function_info::simplify_phi_propagate (phi_info *phi, + set_info **assumed_values, + bitmap curr_worklist, + bitmap next_worklist) +{ + // Go through each phi user of PHI to see whether it needs updating. + unsigned int phi_uid = phi->uid (); + machine_mode phi_mode = phi->mode (); + set_info *phi_value = assumed_values[phi_uid]; + for (use_info *use : phi->phi_uses ()) + { + phi_info *user_phi = use->phi (); + + // Propagate the phi's new mode to all phi users. Insn uses should + // not be updated, since their modes reflect a property of the insns + // rather than the phi. + if (use->mode () != phi_mode) + use->set_mode (phi_mode); + + if (user_phi == phi) + continue; + + // If this is a phi we should be looking at, see whether it needs + // an update. + unsigned int user_phi_uid = user_phi->uid (); + if (user_phi_uid < phi_uid || curr_worklist) + { + bool needs_update = false; + + // Make sure that USER_PHI's mode is at least as big as PHI_MODE. + machine_mode user_phi_mode = user_phi->mode (); + machine_mode new_mode = combine_modes (user_phi_mode, phi_mode); + if (user_phi_mode != new_mode) + { + user_phi->set_mode (new_mode); + needs_update = true; + } + + // If USER_PHI optimistically assumed an incorrect value, + // adjust it now. + if (assumed_values[user_phi_uid] != user_phi + && assumed_values[user_phi_uid] != phi_value) + { + assumed_values[user_phi_uid] = user_phi; + needs_update = true; + } + + if (needs_update) + { + if (user_phi_uid < phi_uid) + bitmap_set_bit (next_worklist, user_phi_uid); + else + bitmap_set_bit (curr_worklist, user_phi_uid); + } + } + } +} + +// Update the modes of all phis so that they are at least as big as +// all inputs. Remove any non-degenerate phis whose inputs are all equal. +void +function_info::simplify_phis () +{ + auto temps = temp_watermark (); + + // See the comment above simplify_phi_setup for details about this array. + auto *assumed_values = XOBNEWVEC (&m_temp_obstack, set_info *, + m_next_phi_uid); + + // An array of all phis, indexed by uid. + auto *phis = XOBNEWVEC (&m_temp_obstack, phi_info *, m_next_phi_uid); + + // Which phi uids are actually in use. + auto_sbitmap valid_phi_uids (m_next_phi_uid); + bitmap_clear (valid_phi_uids); + + // Bitmaps used for the main double-queue propagation phase. + auto_bitmap worklist1; + auto_bitmap worklist2; + bitmap curr_worklist = worklist1; + bitmap next_worklist = worklist2; + + // Perform the set-up phase; see simplify_phi_setup for details. + for (ebb_info *ebb : ebbs ()) + for (phi_info *phi : ebb->phis ()) + { + bitmap_set_bit (valid_phi_uids, phi->uid ()); + phis[phi->uid ()] = phi; + simplify_phi_setup (phi, assumed_values, curr_worklist); + } + + // Iteratively process any phis that need updating; see + // simplify_phi_propagate for details. Using a double queue + // should reduce the number of times that any given phi node + // needs to be revisited. + while (!bitmap_empty_p (curr_worklist)) + { + do + { + unsigned int uid = bitmap_first_set_bit (curr_worklist); + bitmap_clear_bit (curr_worklist, uid); + simplify_phi_propagate (phis[uid], assumed_values, + curr_worklist, next_worklist); + } + while (!bitmap_empty_p (curr_worklist)); + std::swap (next_worklist, curr_worklist); + } + + // Make sure that assumed_values is a transitive closure. This ensures + // that each use_info is only updated once. + if (flag_checking) + for (unsigned int i = 0; i < m_next_phi_uid; ++i) + if (bitmap_bit_p (valid_phi_uids, i)) + if (auto *new_phi = safe_dyn_cast (assumed_values[i])) + gcc_assert (assumed_values[new_phi->uid ()] == new_phi); + + // Update any phis that turned out to be equivalent to a single input. + for (unsigned int i = 0; i < m_next_phi_uid; ++i) + if (bitmap_bit_p (valid_phi_uids, i) && phis[i] != assumed_values[i]) + replace_phi (phis[i], assumed_values[i]); +} + +// Print a description of FUNCTION to PP. +void +rtl_ssa::pp_function (pretty_printer *pp, const function_info *function) +{ + function->print (pp); +} + +// Print a description of FUNCTION to FILE. +void +dump (FILE *file, const function_info *function) +{ + dump_using (file, pp_function, function); +} + +// Debug interface to the dump routine above. +void debug (const function_info *x) { dump (stderr, x); } diff --git a/gcc/rtl-ssa/functions.h b/gcc/rtl-ssa/functions.h new file mode 100644 index 0000000..b09d50e --- /dev/null +++ b/gcc/rtl-ssa/functions.h @@ -0,0 +1,433 @@ +// Function-related RTL SSA classes -*- C++ -*- +// Copyright (C) 2020 Free Software Foundation, Inc. +// +// This file is part of GCC. +// +// GCC is free software; you can redistribute it and/or modify it under +// the terms of the GNU General Public License as published by the Free +// Software Foundation; either version 3, or (at your option) any later +// version. +// +// GCC is distributed in the hope that it will be useful, but WITHOUT ANY +// WARRANTY; without even the implied warranty of MERCHANTABILITY or +// FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License +// for more details. +// +// You should have received a copy of the GNU General Public License +// along with GCC; see the file COPYING3. If not see +// . + +namespace rtl_ssa { + +// SSA-related information about a function. It contains three levels +// of information, each in reverse postorder: +// +// - a list of extended basic blocks +// - a list of basic blocks +// - a list of instructions +// +// It also maintains a list of definitions of memory, and a list of +// definitions of each register. +// +// See doc/rtl.texi for more details about the way this information +// is organized and how changes to it are made. +class function_info +{ + // The default obstack alignment takes long double into account. + // Since we have no use for that here, and since we allocate many + // relatively small objects, it's better to specify an alignment + // explicitly. The allocation routines assert that the alignment + // is enough for the objects being allocated. + // + // Because various structures use pointer_mux, we need at least 2 bytes + // of alignment. + static const size_t obstack_alignment = sizeof (void *); + +public: + // Construct SSA form for function FN. + function_info (function *fn); + ~function_info (); + + // Return a list of all the extended basic blocks in the function, in reverse + // postorder. The list includes the entry and exit blocks. + iterator_range ebbs () const; + + // Like ebbs (), but in the reverse order. + iterator_range reverse_ebbs () const; + + // Return a list of all the basic blocks in the function, in reverse + // postorder. The list includes the entry and exit blocks. + iterator_range bbs () const; + + // Like bbs (), but in the reverse order. + iterator_range reverse_bbs () const; + + // Return the SSA information for the basic block with index INDEX. + bb_info *bb (unsigned int index) const { return m_bbs[index]; } + + // Return the SSA information for CFG_BB. + bb_info *bb (basic_block cfg_bb) const { return m_bbs[cfg_bb->index]; } + + // Return a list of all the instructions in the function, in reverse + // postorder. The list includes both real and artificial instructions. + // + // Iterations over the list will pick up any new instructions that are + // inserted after the iterator's current instruction. + iterator_range all_insns () const; + + // Like all_insns (), but in the reverse order. + // + // Iterations over the list will pick up any new instructions that are + // inserted before the iterator's current instruction. + iterator_range reverse_all_insns () const; + + // Like all_insns (), but without the debug instructions. + iterator_range nondebug_insns () const; + + // Like reverse_all_insns (), but without the debug instructions. + iterator_range + reverse_nondebug_insns () const; + + // Return the first and last instructions in insns (). + insn_info *first_insn () const { return m_first_insn; } + insn_info *last_insn () const { return m_last_insn; } + + // Return a list of all definitions of memory, in reverse postorder. + // This includes both real stores by instructions and artificial + // definitions by things like phi nodes. + iterator_range mem_defs () const; + + // Return a list of all definitions of register REGNO, in reverse postorder. + // This includes both real stores by instructions and artificial + // definitions by things like phi nodes. + iterator_range ref_defs (unsigned int regno) const; + + // Check if all uses of register REGNO are either unconditionally undefined + // or use the same single dominating definition. Return the definition + // if so, otherwise return null. + set_info *single_dominating_def (unsigned int regno) const; + + // Look for a definition of RESOURCE at INSN. Return the result of the + // search as a def_lookup; see the comments there for more details. + def_lookup find_def (resource_info resource, insn_info *insn); + + // Return an RAII object that owns all temporary RTL SSA memory + // allocated during a change attempt. The object should remain in + // scope until the change has been aborted or successfully completed. + obstack_watermark new_change_attempt () { return &m_temp_obstack; } + + // Make a best attempt to check whether the values used by USES are + // available on entry to BB, without solving a full dataflow problem. + // If all the values are already live on entry to BB or can be made + // available there, return a use_array that describes the uses as + // if they occured at the start of BB. These uses are purely temporary, + // and will not become permanent unless applied using change_insns. + // + // If the operation fails, return an invalid use_array. + // + // WATERMARK is a watermark returned by new_change_attempt (). + use_array make_uses_available (obstack_watermark &watermark, + use_array uses, bb_info *bb); + + // If CHANGE doesn't already clobber REGNO, try to add such a clobber, + // limiting the movement range in order to make the clobber valid. + // When determining whether REGNO is live, ignore accesses made by an + // instruction I if IGNORE (I) is true. The caller then assumes the + // responsibility of ensuring that CHANGE and I are placed in a valid order. + // + // Return true on success. Leave CHANGE unmodified when returning false. + // + // WATERMARK is a watermark returned by new_change_attempt (). + template + bool add_regno_clobber (obstack_watermark &watermark, insn_change &change, + unsigned int regno, IgnorePredicate ignore); + + // Return true if change_insns will be able to perform the changes + // described by CHANGES. + bool verify_insn_changes (array_slice changes); + + // Perform all the changes in CHANGES, keeping the instructions in the + // order specified by the CHANGES array. On return, the SSA information + // remains up-to-date. The same is true for instruction-level DF + // information, although the block-level DF information might be + // marked dirty. + void change_insns (array_slice changes); + + // Like change_insns, but for a single change CHANGE. + void change_insn (insn_change &change); + + // If the changes that have been made to instructions require updates + // to the CFG, perform those updates now. Return true if something changed. + // If it did: + // + // - The SSA information is now invalid and needs to be recomputed. + // + // - Dominance information is no longer available (in either direction). + // + // - The caller will need to call cleanup_cfg at some point. + // + // ??? We could probably update the SSA information for simple updates, + // but currently nothing would benefit. These late CFG changes are + // relatively rare anyway, since gimple optimisers should remove most + // unnecessary control flow. + bool perform_pending_updates (); + + // Print the contents of the function to PP. + void print (pretty_printer *pp) const; + +private: + // Information about the values that are live on exit from a basic block. + // This class is only used when constructing the SSA form, it isn't + // designed for being kept up-to-date. + class bb_live_out_info + { + public: + // REG_VALUES contains all the registers that live out from the block, + // in order of increasing register number. There are NUM_REG_VALUES + // in total. Registers do not appear here if their values are known + // to be completely undefined; in that sense, the information is + // closer to DF_LIVE than to DF_LR. + unsigned int num_reg_values; + set_info **reg_values; + + // The memory value that is live on exit from the block. + set_info *mem_value; + }; + + // Information used while constructing the SSA form and discarded + // afterwards. + class build_info + { + public: + set_info *current_reg_value (unsigned int) const; + set_info *current_mem_value () const; + + void record_reg_def (unsigned int, def_info *); + void record_mem_def (def_info *); + + // The block that we're currently processing. + bb_info *current_bb; + + // The EBB that contains CURRENT_BB. + ebb_info *current_ebb; + + // Except for the local exception noted below: + // + // - If register R has been defined in the current EBB, LAST_ACCESS[R + 1] + // is the last definition of R in the EBB. + // + // - If register R is currently live but has not yet been defined + // in the EBB, LAST_ACCESS[R + 1] is the current value of R, + // or null if the register's value is completely undefined. + // + // - The contents are not meaningful for other registers. + // + // Similarly: + // + // - If the current EBB has defined memory, LAST_ACCESS[0] is the last + // definition of memory in the EBB. + // + // - Otherwise LAST_ACCESS[0] is the value of memory that is live on + // - entry to the EBB. + // + // The exception is that while building instructions, LAST_ACCESS[I] + // can temporarily be the use of regno I - 1 by that instruction. + access_info **last_access; + + // A bitmap of registers that are live on entry to this EBB, with a tree + // view for quick lookup. Only used if MAY_HAVE_DEBUG_INSNS. + bitmap ebb_live_in_for_debug; + + // A conservative superset of the registers that are used by + // instructions in CURRENT_EBB. That is, all used registers + // are in the set, but some unused registers might be too. + bitmap ebb_use; + + // A similarly conservative superset of the registers that are defined + // by instructions in CURRENT_EBB. + bitmap ebb_def; + + // BB_LIVE_OUT[BI] gives the live-out values for the basic block + // with index BI. + bb_live_out_info *bb_live_out; + }; + + // Return an RAII object that owns all objects allocated by + // allocate_temp during its lifetime. + obstack_watermark temp_watermark () { return &m_temp_obstack; } + + template + T *allocate (Ts... args); + + template + T *allocate_temp (Ts... args); + + access_array temp_access_array (access_array accesses); + + clobber_group *need_clobber_group (clobber_info *); + def_node *need_def_node (def_info *); + def_splay_tree need_def_splay_tree (def_info *); + + use_info *make_use_available (use_info *, bb_info *); + def_array insert_temp_clobber (obstack_watermark &, insn_info *, + unsigned int, def_array); + + void insert_def_before (def_info *, def_info *); + void insert_def_after (def_info *, def_info *); + void remove_def_from_list (def_info *); + + void add_clobber (clobber_info *, clobber_group *); + void remove_clobber (clobber_info *, clobber_group *); + void prepend_clobber_to_group (clobber_info *, clobber_group *); + void append_clobber_to_group (clobber_info *, clobber_group *); + void merge_clobber_groups (clobber_info *, clobber_info *, + def_info *); + clobber_info *split_clobber_group (clobber_group *, insn_info *); + + void append_def (def_info *); + void add_def (def_info *); + void remove_def (def_info *); + + void need_use_splay_tree (set_info *); + + static void insert_use_before (use_info *, use_info *); + static void insert_use_after (use_info *, use_info *); + + void add_use (use_info *); + void remove_use (use_info *); + + insn_info::order_node *need_order_node (insn_info *); + + void add_insn_after (insn_info *, insn_info *); + void append_insn (insn_info *); + void remove_insn (insn_info *); + + insn_info *append_artificial_insn (bb_info *, rtx_insn * = nullptr); + + void start_insn_accesses (); + void finish_insn_accesses (insn_info *); + + void record_use (build_info &, insn_info *, rtx_obj_reference); + void record_call_clobbers (build_info &, insn_info *, rtx_call_insn *); + void record_def (build_info &, insn_info *, rtx_obj_reference); + void add_insn_to_block (build_info &, rtx_insn *); + + void add_reg_unused_notes (insn_info *); + + void add_live_out_use (bb_info *, set_info *); + set_info *live_out_value (bb_info *, set_info *); + + void append_phi (ebb_info *, phi_info *); + void remove_phi (phi_info *); + void delete_phi (phi_info *); + void replace_phi (phi_info *, set_info *); + phi_info *create_phi (ebb_info *, resource_info, access_info **, + unsigned int); + phi_info *create_degenerate_phi (ebb_info *, set_info *); + + bb_info *create_bb_info (basic_block); + void append_bb (bb_info *); + void calculate_potential_phi_regs (); + + insn_info *add_placeholder_after (insn_info *); + void possibly_queue_changes (insn_change &); + void finalize_new_accesses (insn_change &); + void apply_changes_to_insn (insn_change &); + + void init_function_data (); + void add_entry_block_defs (build_info &); + void add_phi_nodes (build_info &); + void add_artificial_accesses (build_info &, df_ref_flags); + void add_block_contents (build_info &); + void record_block_live_out (build_info &); + void populate_backedge_phis (build_info &); + void process_all_blocks (); + + void simplify_phi_setup (phi_info *, set_info **, bitmap); + void simplify_phi_propagate (phi_info *, set_info **, bitmap, bitmap); + void simplify_phis (); + + // The function that this object describes. + function *m_fn; + + // The lowest (negative) in-use artificial insn uid minus one. + int m_next_artificial_uid; + + // The highest in-use phi uid plus one. + unsigned int m_next_phi_uid; + + // The highest in-use register number plus one. + unsigned int m_num_regs; + + // M_DEFS[R] is the first definition of register R - 1 in a reverse + // postorder traversal of the function, or null if the function has + // no definition of R. Applying last () gives the last definition of R. + // + // M_DEFS[0] is for memory; MEM_REGNO + 1 == 0. + auto_vec m_defs; + + // M_BBS[BI] gives the SSA information about the block with index BI. + auto_vec m_bbs; + + // An obstack used to allocate the main RTL SSA information. + obstack m_obstack; + + // An obstack used for temporary work, such as while building up a list + // of possible instruction changes. + obstack m_temp_obstack; + + // The start of each obstack, so that all memory in them can be freed. + char *m_obstack_start; + char *m_temp_obstack_start; + + // The entry and exit blocks. + bb_info *m_first_bb; + bb_info *m_last_bb; + + // The first and last instructions in a reverse postorder traversal + // of the function. + insn_info *m_first_insn; + insn_info *m_last_insn; + + // The last nondebug instruction in the list of instructions. + // This is only different from m_last_insn when building the initial + // SSA information; after that, the last instruction is always a + // BB end instruction. + insn_info *m_last_nondebug_insn; + + // Temporary working state when building up lists of definitions and uses. + // Keeping them around should reduce the number of unnecessary reallocations. + auto_vec m_temp_defs; + auto_vec m_temp_uses; + + // The set of registers that might need to have phis associated with them. + // Registers outside this set are known to have a single definition that + // dominates all uses. + // + // Before RA, about 5% of registers are typically in the set. + auto_bitmap m_potential_phi_regs; + + // A list of phis that are no longer in use. Their uids are still unique + // and so can be recycled. + phi_info *m_free_phis; + + // A list of instructions that have been changed in ways that need + // further processing later, such as removing dead instructions or + // altering the CFG. + auto_vec m_queued_insn_updates; + + // The INSN_UIDs of all instructions in M_QUEUED_INSN_UPDATES. + auto_bitmap m_queued_insn_update_uids; + + // A basic_block is in this bitmap if we need to call purge_dead_edges + // on it. As with M_QUEUED_INSN_UPDATES, these updates are queued until + // a convenient point. + auto_bitmap m_need_to_purge_dead_edges; +}; + +void pp_function (pretty_printer *, const function_info *); +} + +void dump (FILE *, const rtl_ssa::function_info *); + +void DEBUG_FUNCTION debug (const rtl_ssa::function_info *); diff --git a/gcc/rtl-ssa/insn-utils.h b/gcc/rtl-ssa/insn-utils.h new file mode 100644 index 0000000..d7705e9 --- /dev/null +++ b/gcc/rtl-ssa/insn-utils.h @@ -0,0 +1,46 @@ +// Instruction-related utilities for RTL SSA -*- C++ -*- +// Copyright (C) 2020 Free Software Foundation, Inc. +// +// This file is part of GCC. +// +// GCC is free software; you can redistribute it and/or modify it under +// the terms of the GNU General Public License as published by the Free +// Software Foundation; either version 3, or (at your option) any later +// version. +// +// GCC is distributed in the hope that it will be useful, but WITHOUT ANY +// WARRANTY; without even the implied warranty of MERCHANTABILITY or +// FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License +// for more details. +// +// You should have received a copy of the GNU General Public License +// along with GCC; see the file COPYING3. If not see +// . + +namespace rtl_ssa { + +// Return whichever of INSN1 and INSN2 occurs earlier in the function's +// reverse postorder. +inline insn_info * +earlier_insn (insn_info *insn1, insn_info *insn2) +{ + return *insn1 < *insn2 ? insn1 : insn2; +} + +// Return whichever of INSN1 and INSN2 occurs later in the function's +// reverse postorder. +inline insn_info * +later_insn (insn_info *insn1, insn_info *insn2) +{ + return *insn1 < *insn2 ? insn2 : insn1; +} + +// Return a closure of operator== for INSN. See insn_is_changing for +// the rationale for defining the function this way. +inline insn_is_closure +insn_is (const insn_info *insn) +{ + return insn_is_closure (insn); +} + +} diff --git a/gcc/rtl-ssa/insns.cc b/gcc/rtl-ssa/insns.cc new file mode 100644 index 0000000..b8e08ff --- /dev/null +++ b/gcc/rtl-ssa/insns.cc @@ -0,0 +1,718 @@ +// Implementation of instruction-related RTL SSA functions -*- C++ -*- +// Copyright (C) 2020 Free Software Foundation, Inc. +// +// This file is part of GCC. +// +// GCC is free software; you can redistribute it and/or modify it under +// the terms of the GNU General Public License as published by the Free +// Software Foundation; either version 3, or (at your option) any later +// version. +// +// GCC is distributed in the hope that it will be useful, but WITHOUT ANY +// WARRANTY; without even the implied warranty of MERCHANTABILITY or +// FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License +// for more details. +// +// You should have received a copy of the GNU General Public License +// along with GCC; see the file COPYING3. If not see +// . + +#define INCLUDE_ALGORITHM +#define INCLUDE_FUNCTIONAL +#include "config.h" +#include "system.h" +#include "coretypes.h" +#include "backend.h" +#include "rtl.h" +#include "df.h" +#include "rtl-ssa.h" +#include "rtl-ssa/internals.inl" +#include "predict.h" +#include "print-rtl.h" +#include "rtl-iter.h" + +using namespace rtl_ssa; + +// The gap to leave between program points when building up the list +// of instructions for the first time. Using 2 allows an instruction +// to be inserted between two others without resorting to splay tree +// ordering. Using 0 is useful as a debugging aid to stress the +// splay tree code. +static const unsigned int POINT_INCREASE = 2; + +// Calculate and record the cost of the instruction, based on the +// form it had before any in-progress changes were made. +void +insn_info::calculate_cost () const +{ + basic_block cfg_bb = BLOCK_FOR_INSN (m_rtl); + temporarily_undo_changes (0); + m_cost_or_uid = insn_cost (m_rtl, optimize_bb_for_speed_p (cfg_bb)); + redo_changes (0); +} + +// Add NOTE to the instruction's notes. +void +insn_info::add_note (insn_note *note) +{ + insn_note **ptr = &m_first_note; + // Always put the order node first, since it's the one that's likely + // to be used most often. + if (*ptr && (*ptr)->kind () == insn_note_kind::ORDER_NODE) + ptr = &(*ptr)->m_next_note; + note->m_next_note = *ptr; + *ptr = note; +} + +// Implement compare_with for the case in which this insn and OTHER +// have the same program point. +int +insn_info::slow_compare_with (const insn_info &other) const +{ + return order_splay_tree::compare_nodes (get_known_order_node (), + other.get_known_order_node ()); +} + +// Print insn uid UID to PP, where UID has the same form as insn_info::uid. +void +insn_info::print_uid (pretty_printer *pp, int uid) +{ + char tmp[3 * sizeof (uid) + 2]; + if (uid < 0) + // An artificial instruction. + snprintf (tmp, sizeof (tmp), "a%d", -uid); + else + // A real RTL instruction. + snprintf (tmp, sizeof (tmp), "i%d", uid); + pp_string (pp, tmp); +} + +// See comment above declaration. +void +insn_info::print_identifier (pretty_printer *pp) const +{ + print_uid (pp, uid ()); +} + +// See comment above declaration. +void +insn_info::print_location (pretty_printer *pp) const +{ + if (bb_info *bb = this->bb ()) + { + ebb_info *ebb = bb->ebb (); + if (ebb && is_phi ()) + ebb->print_identifier (pp); + else + bb->print_identifier (pp); + pp_string (pp, " at point "); + pp_decimal_int (pp, m_point); + } + else + pp_string (pp, ""); +} + +// See comment above declaration. +void +insn_info::print_identifier_and_location (pretty_printer *pp) const +{ + if (m_is_asm) + pp_string (pp, "asm "); + if (m_is_debug_insn) + pp_string (pp, "debug "); + pp_string (pp, "insn "); + print_identifier (pp); + pp_string (pp, " in "); + print_location (pp); +} + +// See comment above declaration. +void +insn_info::print_full (pretty_printer *pp) const +{ + print_identifier_and_location (pp); + pp_colon (pp); + if (is_real ()) + { + pp_newline_and_indent (pp, 2); + if (has_been_deleted ()) + pp_string (pp, "deleted"); + else + { + // Print the insn pattern to a temporary printer. + pretty_printer sub_pp; + print_insn_with_notes (&sub_pp, rtl ()); + const char *text = pp_formatted_text (&sub_pp); + + // Calculate the length of the maximum line in the pattern. + unsigned int max_len = 0; + const char *start = text; + while (const char *end = strchr (start, '\n')) + { + max_len = MAX (max_len, (unsigned int) (end - start)); + start = end + 1; + } + + // Print a separator before or after the pattern. + auto print_top_bottom = [&]() + { + pp_character (pp, '+'); + for (unsigned int i = 0; i < max_len + 2; ++i) + pp_character (pp, '-'); + }; + + print_top_bottom (); + start = text; + while (const char *end = strchr (start, '\n')) + { + pp_newline_and_indent (pp, 0); + pp_character (pp, '|'); + // Each line of the pattern already starts with a space. + // so we don't need to add another one here. + pp_append_text (pp, start, end); + start = end + 1; + } + pp_newline_and_indent (pp, 0); + print_top_bottom (); + + if (m_cost_or_uid != UNKNOWN_COST) + { + pp_newline_and_indent (pp, 0); + pp_string (pp, "cost: "); + pp_decimal_int (pp, m_cost_or_uid); + } + if (m_has_pre_post_modify) + { + pp_newline_and_indent (pp, 0); + pp_string (pp, "has pre/post-modify operations"); + } + if (m_has_volatile_refs) + { + pp_newline_and_indent (pp, 0); + pp_string (pp, "has volatile refs"); + } + } + pp_indentation (pp) -= 2; + } + + auto print_accesses = [&](const char *heading, access_array accesses, + unsigned int flags) + { + if (!accesses.empty ()) + { + pp_newline_and_indent (pp, 2); + pp_string (pp, heading); + pp_newline_and_indent (pp, 2); + pp_accesses (pp, accesses, flags); + pp_indentation (pp) -= 4; + } + }; + + print_accesses ("uses:", uses (), PP_ACCESS_USER); + auto *call_clobbers_note = find_note (); + if (call_clobbers_note) + { + pp_newline_and_indent (pp, 2); + pp_string (pp, "has call clobbers for ABI "); + pp_decimal_int (pp, call_clobbers_note->abi_id ()); + pp_indentation (pp) -= 2; + } + print_accesses ("defines:", defs (), PP_ACCESS_SETTER); + if (num_uses () == 0 && !call_clobbers_note && num_defs () == 0) + { + pp_newline_and_indent (pp, 2); + pp_string (pp, "has no uses or defs"); + pp_indentation (pp) -= 2; + } + + if (order_node *node = get_order_node ()) + { + while (node->m_parent) + node = node->m_parent; + + pp_newline_and_indent (pp, 2); + pp_string (pp, "insn order: "); + pp_newline_and_indent (pp, 2); + auto print_order = [](pretty_printer *pp, order_node *node) + { + print_uid (pp, node->uid ()); + }; + order_splay_tree::print (pp, node, print_order); + pp_indentation (pp) -= 4; + } +} + +// Return an insn_info::order_node for INSN, creating one if necessary. +insn_info::order_node * +function_info::need_order_node (insn_info *insn) +{ + insn_info::order_node *order = insn->get_order_node (); + if (!order) + { + order = allocate (insn->uid ()); + insn->add_note (order); + } + return order; +} + +// Add instruction INSN immediately after AFTER in the reverse postorder list. +// INSN is not currently in the list. +void +function_info::add_insn_after (insn_info *insn, insn_info *after) +{ + gcc_checking_assert (!insn->has_insn_links ()); + + insn->copy_next_from (after); + after->set_next_any_insn (insn); + + // The prev link is easy if AFTER and INSN are the same type. + // Handle the other cases below. + if (after->is_debug_insn () == insn->is_debug_insn ()) + insn->set_prev_sametype_insn (after); + + if (insn_info *next = insn->next_any_insn ()) + { + if (insn->is_debug_insn () == next->is_debug_insn ()) + { + // INSN might now be the start of the subsequence of debug insns, + // and so its prev pointer might point to the end of the subsequence + // instead of AFTER. + insn->copy_prev_from (next); + next->set_prev_sametype_insn (insn); + } + else if (insn->is_debug_insn ()) // && !next->is_debug_insn () + { + // INSN ends a subsequence of debug instructions. Find the + // first debug instruction in the subsequence, which might + // be INSN itself. (If it isn't, then AFTER is also a debug + // instruction and we updated INSN's prev link above.) + insn_info *first = next->prev_nondebug_insn ()->next_any_insn (); + first->set_last_debug_insn (insn); + } + else // !insn->is_debug_insn () && next->is_debug_insn () + // At present we don't (need to) support inserting a nondebug + // instruction between two existing debug instructions. + gcc_assert (!after->is_debug_insn ()); + + // If AFTER and NEXT are separated by at least two points, we can + // use a unique point number for INSN. Otherwise INSN will have + // the same point number as AFTER. + insn->set_point ((next->point () + after->point ()) / 2); + } + else + { + if (!insn->is_debug_insn ()) + { + insn->set_prev_sametype_insn (m_last_nondebug_insn); + m_last_nondebug_insn = insn; + } + else + // There is now at least one debug instruction after + // m_last_nondebug_insn: either INSN itself, or the start of + // a longer subsequence of debug insns that now ends with AFTER + // followed by INSN. + m_last_nondebug_insn->next_any_insn ()->set_last_debug_insn (insn); + m_last_insn = insn; + + insn->set_point (after->point () + POINT_INCREASE); + } + + // If INSN's program point is the same as AFTER's, we need to use the + // splay tree to record their relative order. + if (insn->point () == after->point ()) + { + insn_info::order_node *after_node = need_order_node (after); + insn_info::order_node *insn_node = need_order_node (insn); + insn_info::order_splay_tree::insert_child (after_node, 1, insn_node); + } +} + +// Remove INSN from the function's list of instructions. +void +function_info::remove_insn (insn_info *insn) +{ + if (insn_info::order_node *order = insn->get_order_node ()) + insn_info::order_splay_tree::remove_node (order); + + if (auto *note = insn->find_note ()) + { + ebb_call_clobbers_info *ecc = insn->ebb ()->first_call_clobbers (); + while (ecc->abi ()->id () != note->abi_id ()) + ecc = ecc->next (); + int comparison = lookup_call_clobbers (*ecc, insn); + gcc_assert (comparison == 0); + ecc->remove_root (); + } + + insn_info *prev = insn->prev_any_insn (); + insn_info *next = insn->next_any_insn (); + insn_info *prev_nondebug = insn->prev_nondebug_insn (); + insn_info *next_nondebug = insn->next_nondebug_insn (); + + // We should never remove the entry or exit block's instructions. + // At present we also don't remove entire blocks, so should never + // remove debug instructions. + gcc_checking_assert (prev_nondebug + && next_nondebug + && !insn->is_debug_insn ()); + + if (prev->is_debug_insn () && next->is_debug_insn ()) + { + // We need to stitch together two subsequences of debug insns. + insn_info *last = next->last_debug_insn (); + next->set_prev_sametype_insn (prev); + prev_nondebug->next_any_insn ()->set_last_debug_insn (last); + } + prev->set_next_any_insn (next); + next_nondebug->set_prev_sametype_insn (prev_nondebug); + + insn->clear_insn_links (); +} + +// Create an artificial instruction for BB, associating it with RTL (which can +// be null). Add the new instruction to the end of the function's list and +// return the new instruction. +insn_info * +function_info::append_artificial_insn (bb_info *bb, rtx_insn *rtl) +{ + insn_info *insn = allocate (bb, rtl, m_next_artificial_uid); + m_next_artificial_uid -= 1; + append_insn (insn); + return insn; +} + +// Finish building a new list of uses and definitions for instruction INSN. +void +function_info::finish_insn_accesses (insn_info *insn) +{ + unsigned int num_defs = m_temp_defs.length (); + unsigned int num_uses = m_temp_uses.length (); + obstack_make_room (&m_obstack, num_defs + num_uses); + if (num_defs) + { + sort_accesses (m_temp_defs); + obstack_grow (&m_obstack, m_temp_defs.address (), + num_defs * sizeof (access_info *)); + m_temp_defs.truncate (0); + } + if (num_uses) + { + sort_accesses (m_temp_uses); + obstack_grow (&m_obstack, m_temp_uses.address (), + num_uses * sizeof (access_info *)); + m_temp_uses.truncate (0); + } + void *addr = obstack_finish (&m_obstack); + insn->set_accesses (static_cast (addr), num_defs, num_uses); +} + +// Called while building SSA form using BI. Record that INSN contains +// read reference REF. If this requires new entries to be added to +// INSN->uses (), add those entries to the list we're building in +// m_temp_uses. +void +function_info::record_use (build_info &bi, insn_info *insn, + rtx_obj_reference ref) +{ + unsigned int regno = ref.regno; + machine_mode mode = ref.is_reg () ? ref.mode : BLKmode; + access_info *access = bi.last_access[ref.regno + 1]; + use_info *use = safe_dyn_cast (access); + if (!use) + { + set_info *value = safe_dyn_cast (access); + // In order to ensure that -g doesn't affect codegen, uses in debug + // instructions do not affect liveness, either in DF or here. + // This means that there might be no correct definition of the resource + // available (e.g. if it would require a phi node that the nondebug + // code doesn't need). Perhaps we could have "debug phi nodes" as + // well as "debug instructions", but that would require a method + // of building phi nodes that didn't depend on DF liveness information, + // and so might be significantly more expensive. + // + // Therefore, the only value we try to attach to a use by a debug + // instruction is VALUE itself (as we would for nondebug instructions). + // We then need to make a conservative check for whether VALUE is + // actually correct. + auto value_is_valid = [&]() + { + // Memmory always has a valid definition. + if (ref.is_mem ()) + return true; + + // If VALUE would lead to an uninitialized use anyway, there's + // nothing to check. + if (!value) + return false; + + // If the previous definition occurs in the same EBB then it + // is certainly correct. + if (value->ebb () == bi.current_ebb) + return true; + + // If the register is live on entry to the EBB but not used + // within it, VALUE is the correct live-in value. + if (bitmap_bit_p (bi.ebb_live_in_for_debug, regno)) + return true; + + // Check if VALUE is the function's only definition of REGNO + // and if it dominates the use. + if (regno != MEM_REGNO + && regno < DF_REG_SIZE (DF) + && DF_REG_DEF_COUNT (regno) == 1 + && dominated_by_p (CDI_DOMINATORS, insn->bb ()->cfg_bb (), + value->bb ()->cfg_bb ())) + return true; + + // Punt for other cases. + return false; + }; + if (insn->is_debug_insn () && !value_is_valid ()) + value = nullptr; + + use = allocate (insn, resource_info { mode, regno }, value); + add_use (use); + m_temp_uses.safe_push (use); + bi.last_access[ref.regno + 1] = use; + use->record_reference (ref, true); + } + else + { + // Record the mode of the largest use. The choice is arbitrary if + // the instruction (unusually) references the same register in two + // different but equal-sized modes. + gcc_checking_assert (use->insn () == insn); + if (HARD_REGISTER_NUM_P (regno) + && partial_subreg_p (use->mode (), mode)) + use->set_mode (mode); + use->record_reference (ref, false); + } +} + +// Called while building SSA form for INSN using BI. Record the effect +// of call clobbers in RTL. We have already added the explicit sets and +// clobbers for RTL, which have priority over any call clobbers. +void +function_info::record_call_clobbers (build_info &bi, insn_info *insn, + rtx_call_insn *rtl) +{ + // See whether we should record this call in the EBB's list of + // call clobbers. Three things affect this choice: + // + // (1) The list is the only way we have of recording partial clobbers. + // All calls that only partially clobber registers must therefore + // be in the list. + // + // (2) Adding calls to the list is much more memory-efficient than + // creating a long list of clobber_infos. + // + // (3) Adding calls to the list limits the ability to move definitions + // of registers that are normally fully or partially clobbered + // by the associated predefined ABI. So adding calls to the list + // can hamper optimization if (thanks to -fipa-ra) the number of + // clobbers is much smaller than the usual set. + // + // The trade-off that we currently take is to use the list if there + // are some registers that the call only partially clobbers or if + // the set of clobbers is the standard set. + function_abi abi = insn_callee_abi (rtl); + if (abi.base_abi ().full_reg_clobbers () == abi.full_reg_clobbers () + || abi.full_and_partial_reg_clobbers () != abi.full_reg_clobbers ()) + { + // Find an entry for this predefined ABI, creating one if necessary. + ebb_call_clobbers_info *ecc = bi.current_ebb->first_call_clobbers (); + while (ecc && ecc->abi () != &abi.base_abi ()) + ecc = ecc->next (); + if (!ecc) + { + ecc = allocate (&abi.base_abi ()); + ecc->m_next = bi.current_ebb->first_call_clobbers (); + bi.current_ebb->set_first_call_clobbers (ecc); + } + + auto abi_id = abi.base_abi ().id (); + auto *insn_clobbers = allocate (abi_id, insn); + insn->add_note (insn_clobbers); + + ecc->insert_max_node (insn_clobbers); + } + else + for (unsigned int regno = 0; regno < FIRST_PSEUDO_REGISTER; ++regno) + if (TEST_HARD_REG_BIT (abi.full_reg_clobbers (), regno)) + { + def_info *def = m_defs[regno + 1]; + if (!def || def->last_def ()->insn () != insn) + { + def = allocate (insn, regno); + def->m_is_call_clobber = true; + append_def (def); + m_temp_defs.safe_push (def); + bi.last_access[regno + 1] = def; + } + } +} + +// Called while building SSA form using BI. Record that INSN contains +// write reference REF. Add associated def_infos to the list of accesses +// that we're building in m_temp_defs. Record the register's new live +// value in BI. +void +function_info::record_def (build_info &bi, insn_info *insn, + rtx_obj_reference ref) +{ + // Punt if we see multiple definitions of the same resource. + // This can happen for several reasons: + // + // - An instruction might store two values to memory at once, giving two + // distinct memory references. + // + // - An instruction might assign to multiple pieces of a wide pseudo + // register. For example, on 32-bit targets, an instruction might + // assign to both the upper and lower halves of a 64-bit pseudo register. + // + // - It's possible for the same register to be clobbered by the + // CALL_INSN_FUNCTION_USAGE and to be set by the main instruction + // pattern as well. In that case, the clobber conceptually happens + // before the set and can essentially be ignored. + // + // - Similarly, global registers are implicitly set by a call but can + // be explicitly set or clobbered as well. In that situation, the sets + // are listed first and should win over a clobber. + unsigned int regno = ref.regno; + machine_mode mode = ref.is_reg () ? ref.mode : BLKmode; + def_info *def = safe_dyn_cast (bi.last_access[ref.regno + 1]); + if (def && def->insn () == insn) + { + if (!ref.is_clobber ()) + { + gcc_checking_assert (!is_a (def)); + def->record_reference (ref, false); + } + return; + } + + // Memory is always well-defined, so only use clobber_infos for registers. + if (ref.is_reg () && ref.is_clobber ()) + def = allocate (insn, regno); + else + def = allocate (insn, resource_info { mode, regno }); + def->record_reference (ref, true); + append_def (def); + m_temp_defs.safe_push (def); + bi.last_access[ref.regno + 1] = def; +} + +// Called while building SSA form using BI. Add an insn_info for RTL +// to the block that we're current building. +void +function_info::add_insn_to_block (build_info &bi, rtx_insn *rtl) +{ + insn_info *insn = allocate (bi.current_bb, rtl, UNKNOWN_COST); + append_insn (insn); + + vec_rtx_properties properties; + properties.add_insn (rtl, true); + insn->set_properties (properties); + + start_insn_accesses (); + + // Record the uses. + for (rtx_obj_reference ref : properties.refs ()) + if (ref.is_read ()) + record_use (bi, insn, ref); + + // Restore the contents of bi.last_access, which we used as a cache + // when assembling the uses. + for (access_info *access : m_temp_uses) + { + unsigned int regno = access->regno (); + gcc_checking_assert (bi.last_access[regno + 1] == access); + bi.last_access[regno + 1] = as_a (access)->def (); + } + + // Record the definitions. + for (rtx_obj_reference ref : properties.refs ()) + if (ref.is_write ()) + record_def (bi, insn, ref); + + // Logically these happen before the explicit definitions, but if the + // explicit definitions and call clobbers reference the same register, + // the explicit definition should win. + if (auto *call_rtl = dyn_cast (rtl)) + record_call_clobbers (bi, insn, call_rtl); + + finish_insn_accesses (insn); +} + +// Check whether INSN sets any registers that are never subsequently used. +// If so, add REG_UNUSED notes for them. The caller has already removed +// any previous REG_UNUSED notes. +void +function_info::add_reg_unused_notes (insn_info *insn) +{ + rtx_insn *rtl = insn->rtl (); + + auto handle_potential_set = [&](rtx pattern) + { + if (GET_CODE (pattern) != SET) + return; + + rtx dest = SET_DEST (pattern); + if (!REG_P (dest)) + return; + + def_array defs = insn->defs (); + unsigned int index = find_access_index (defs, REGNO (dest)); + for (unsigned int i = 0; i < REG_NREGS (dest); ++i) + { + def_info *def = defs[index + i]; + gcc_checking_assert (def->regno () == REGNO (dest) + i); + set_info *set = dyn_cast (def); + if (set && set->has_nondebug_uses ()) + return; + } + add_reg_note (rtl, REG_UNUSED, dest); + }; + + rtx pattern = PATTERN (rtl); + if (GET_CODE (pattern) == PARALLEL) + for (int i = 0; i < XVECLEN (pattern, 0); ++i) + handle_potential_set (XVECEXP (pattern, 0, i)); + else + handle_potential_set (pattern); +} + +// Search TREE for call clobbers at INSN. Return: +// +// - less than zero if INSN occurs before the root of TREE +// - 0 if INSN is the root of TREE +// - greater than zero if INSN occurs after the root of TREE +int +rtl_ssa::lookup_call_clobbers (insn_call_clobbers_tree &tree, insn_info *insn) +{ + auto compare = [&](insn_call_clobbers_note *clobbers) + { + return insn->compare_with (clobbers->insn ()); + }; + return tree.lookup (compare); +} + +// Print a description of INSN to PP. +void +rtl_ssa::pp_insn (pretty_printer *pp, const insn_info *insn) +{ + if (!insn) + pp_string (pp, ""); + else + insn->print_full (pp); +} + +// Print a description of INSN to FILE. +void +dump (FILE *file, const insn_info *insn) +{ + dump_using (file, pp_insn, insn); +} + +// Debug interface to the dump routine above. +void debug (const insn_info *x) { dump (stderr, x); } diff --git a/gcc/rtl-ssa/insns.h b/gcc/rtl-ssa/insns.h new file mode 100644 index 0000000..a663103 --- /dev/null +++ b/gcc/rtl-ssa/insns.h @@ -0,0 +1,505 @@ +// Instruction-related RTL SSA classes -*- C++ -*- +// Copyright (C) 2020 Free Software Foundation, Inc. +// +// This file is part of GCC. +// +// GCC is free software; you can redistribute it and/or modify it under +// the terms of the GNU General Public License as published by the Free +// Software Foundation; either version 3, or (at your option) any later +// version. +// +// GCC is distributed in the hope that it will be useful, but WITHOUT ANY +// WARRANTY; without even the implied warranty of MERCHANTABILITY or +// FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License +// for more details. +// +// You should have received a copy of the GNU General Public License +// along with GCC; see the file COPYING3. If not see +// . + +namespace rtl_ssa { + +// A fake cost for instructions that we haven't costed yet. +const int UNKNOWN_COST = INT_MAX; + +// Enumerates the kinds of note that can be added to an instruction. +// See the comment above insn_info for details. +enum class insn_note_kind : uint8_t +{ + ORDER_NODE, + CALL_CLOBBERS +}; + +// The base class for notes that can be added to an instruction. +// See the comment above insn_info for details. +class insn_note +{ + // Size: 2 LP64 words. + friend class insn_info; + friend class function_info; + +public: + // Return what kind of note this is. + insn_note_kind kind () const { return m_kind; } + + // Return the next note in the list, or null if none. + insn_note *next_note () const { return m_next_note; } + + // Used with T = Derived *, where Derived is derived from insn_note. + // Convert the note to Derived, asserting that it has the right kind. + template + T as_a (); + + // Used with T = Derived *, where Derived is derived from insn_note. + // If the note is a Derived note, return it in that form, otherwise + // return null. + template + T dyn_cast (); + +protected: + // Construct a note with the given kind. + insn_note (insn_note_kind); + +private: + // The next note in the list, or null if none. + insn_note *m_next_note; + + // The kind of note this is. + insn_note_kind m_kind : 8; + +protected: + // Fill in the remaining LP64 word with data that derived classes can use. + unsigned int m_data8 : 8; + unsigned int m_data16 : 16; + unsigned int m_data32 : 32; +}; + +// Instructions have one of these notes if insn_info::has_call_clobbers () +// is true. All such instructions in an EBB are first grouped together +// by the predefined_function_abis of the functions that they call. +// Then, for each such predefined ABI, the call_clobbers notes are put +// into a splay tree whose nodes follow execution order. +class insn_call_clobbers_note : public insn_note +{ + friend class function_info; + friend class default_splay_tree_accessors; + +public: + static const insn_note_kind kind = insn_note_kind::CALL_CLOBBERS; + + // Return the identifier of the predefined_function_abi. + unsigned int abi_id () const { return m_data32; } + + // Return the instruction to which the note is attached. + insn_info *insn () const { return m_insn; } + +protected: + insn_call_clobbers_note (unsigned int abi_id, insn_info *insn); + + // The splay tree pointers. + insn_call_clobbers_note *m_children[2]; + + // The value returned by insn (). + insn_info *m_insn; +}; + +// A splay tree of insn_call_clobbers_notes. +using insn_call_clobbers_tree = default_splay_tree; + +// SSA-related information about an instruction. It also represents +// artificial instructions that are added to make the dataflow correct; +// these artificial instructions fall into three categories: +// +// - Instructions that hold the phi nodes for an extended basic block (is_phi). +// +// - Instructions that represent the head of a basic block and that hold +// all the associated artificial uses and definitions. +// +// - Instructions that represent the end of a basic block and that again +// hold all the associated artificial uses and definitions. +// +// Dataflow-wise, each instruction goes through three stages: +// +// (1) Use all the values in uses (). +// +// (2) If has_call_clobbers (), clobber the registers indicated by +// insn_callee_abi. +// +// (3) Define all the values in defs (). +// +// Having stage (2) is a trade-off: it makes processing the instructions +// more complicated, but it saves having to allocate memory for every +// individual call clobber. Without it, clobbers for calls would often +// make up a large proportion of the total definitions in a function. +// +// All the instructions in a function are chained together in a list +// that follows a reverse postorder traversal of the CFG. The list +// contains both debug and nondebug instructions, but it is possible +// to hop from one nondebug instruction to the next with constant complexity. +// +// Instructions can have supplemental information attached in the form +// of "notes", a bit like REG_NOTES for the underlying RTL insns. +class insn_info +{ + // Size: 8 LP64 words. + friend class ebb_info; + friend class function_info; + +public: + // Compare instructions by their positions in the function list described + // above. Thus for two instructions in the same basic block, I1 < I2 if + // I1 comes before I2 in the block. + bool operator< (const insn_info &) const; + bool operator<= (const insn_info &) const; + bool operator>= (const insn_info &) const; + bool operator> (const insn_info &) const; + + // Return -1 if this instruction comes before INSN in the reverse + // postorder, 0 if this instruction is INSN, or 1 if this instruction + // comes after INSN in the reverse postorder. + int compare_with (const insn_info *insn) const; + + // Return the previous and next instructions in the list described above, + // or null if there are no such instructions. + insn_info *prev_any_insn () const; + insn_info *next_any_insn () const; + + // Only valid if !is_debug_insn (). Return the previous and next + // nondebug instructions in the list described above, skipping over + // any intervening debug instructions. These are constant-time operations. + insn_info *prev_nondebug_insn () const; + insn_info *next_nondebug_insn () const; + + // Return the underlying RTL insn. This instruction is null if is_phi () + // or is_bb_end () are true. The instruction is a basic block note if + // is_bb_head () is true. + rtx_insn *rtl () const { return m_rtl; } + + // Return true if the instruction is a real insn with an rtl pattern. + // Return false if it is an artificial instruction that represents the + // phi nodes in an extended basic block or the head or end of a basic block. + bool is_real () const { return m_cost_or_uid >= 0; } + + // Return the opposite of is_real (). + bool is_artificial () const { return m_cost_or_uid < 0; } + + // Return true if the instruction was a real instruction but has now + // been deleted. In this case the instruction is no longer part of + // the SSA information. + bool has_been_deleted () const { return m_rtl && !INSN_P (m_rtl); } + + // Return true if the instruction is a debug instruction (and thus + // also a real instruction). + bool is_debug_insn () const { return m_is_debug_insn; } + + // Return true if the instruction is something that we can optimize. + // This implies that it is a real instruction that contains an asm + // or that contains something that matches an .md define_insn pattern. + bool can_be_optimized () const { return m_can_be_optimized; } + + // Return true if the instruction is a call instruction. + // + // ??? We could cache this information, but since most callers would + // go on to access PATTERN (rtl ()), a cache might not be helpful and + // could even be counterproductive. + bool is_call () const { return CALL_P (m_rtl); } + + // Return true if the instruction is a jump instruction. + // + // ??? See is_call for the reason we don't cache this. + bool is_jump () const { return JUMP_P (m_rtl); } + + // Return true if the instruction is real and contains an inline asm. + bool is_asm () const { return m_is_asm; } + + // Return true if the instruction is real and includes an RTX_AUTOINC + // operation. + bool has_pre_post_modify () const { return m_has_pre_post_modify; } + + // Return true if the instruction is real and has volatile references, + // in the sense of volatile_refs_p. This includes volatile memory, + // volatile asms and UNSPEC_VOLATILEs. + bool has_volatile_refs () const { return m_has_volatile_refs; } + + // Return true if the instruction is aritificial and if its (sole) + // purpose is to hold the phi nodes in an extended basic block. + bool is_phi () const; + + // Return true if the instruction is artificial and if it represents + // the head of a basic block. If so, the instruction conceptually + // executes before the real instructions in the block. The uses + // and definitions represent the df_get_artificial_uses and + // df_get_artificial_defs entries for the head of the block. + bool is_bb_head () const; + + // Return true if the instruction is artificial and if it represents + // the end of a basic block. The uses and definitions represent the + // the df_get_artificial_uses and df_get_artificial_defs entries for + // the end of the block. + bool is_bb_end () const; + + // Return the basic block that the instruction is in. + bb_info *bb () const { return m_bb; } + + // Return the extended basic block that the instruction is in; + // see bb_info for details. + ebb_info *ebb () const; + + // If the instruction is real, return the unique identifier of the + // underlying RTL insn. If the instruction is artificial, return + // a unique negative identifier for the instructions. + // + // Note that the identifiers are not linear: it can be the case that + // an instruction with a higher uid comes earlier in a block than an + // instruction with a lower uid. The identifiers are however persistent; + // the identifier remains the same after the instruction has been moved + // or changed. + int uid () const; + + // Return the list of things that this instruction uses. Registers + // come first, in register number order, followed by memory. + use_array uses () const; + + // Return true if the instruction is a call and if the clobbers + // described by insn_callee_abi have been omitted from the list + // of definitions. + bool has_call_clobbers () const; + + // Return the list of things that this instruction sets or clobbers. + // Registers come first, in register number order, followed by memory. + // + // If has_call_clobbers () is true, the list omits both the full and + // partial register clobbers described by insn_callee_abi. + def_array defs () const; + + // The number of entries in uses (). + unsigned int num_uses () const { return m_num_uses; } + + // The number of entries in defs (). + unsigned int num_defs () const { return m_num_defs; } + + // Return the cost of the instruction, as calculated by the target. + // For performance reasons, the cost is evaluated lazily on first use. + // + // Artificial instructions have a cost of 0. + unsigned int cost () const; + + // Return the first insn_note attached to the instruction, or null + // if none. + insn_note *first_note () const { return m_first_note; } + + // See if a note of type T is attached to the instruction. Return it + // if so, otherwise return null. + template + const T *find_note () const; + + // Print "i" + uid () for real instructions and "a" + -uid () for + // artificial instructions. + void print_identifier (pretty_printer *) const; + + // Print a short(ish) description of where the instruction is. + void print_location (pretty_printer *) const; + + // Combine print_identifier and print_location. + void print_identifier_and_location (pretty_printer *) const; + + // Print a full description of the instruction. + void print_full (pretty_printer *) const; + +private: + // The first-order way of representing the order between instructions + // is to assign "program points", with higher point numbers coming + // later in the reverse postorder than lower point numbers. However, + // after a sequence of instruction movements, we may end up in a situation + // that adjacent instructions have the same program point. + // + // When that happens, we put the instructions into a splay tree that + // records their relative order. Each node of the splay tree is an + // order_node note that is attached to its respective instruction. + // The root of the splay tree is not stored, since the only thing + // we need the tree for is to compare two nodes. + class order_node : public insn_note + { + public: + static const insn_note_kind kind = insn_note_kind::ORDER_NODE; + + order_node (int uid); + + // Return the uid of the instruction that this node describes. + int uid () const { return m_data32; } + + // The splay tree pointers. + order_node *m_children[2]; + order_node *m_parent; + }; + using order_splay_tree = default_rootless_splay_tree; + + // prev_insn_or_last_debug_insn represents a choice between two things: + // + // (1) A pointer to the previous instruction in the list that has the + // same is_debug_insn () value, or null if no such instruction exists. + // + // (2) A pointer to the end of a sublist of debug instructions. + // + // (2) is used if this instruction is a debug instruction and the + // previous instruction is not. (1) is used otherwise. + // + // next_nondebug_or_debug_insn points to the next instruction but also + // records whether that next instruction is a debug instruction or a + // nondebug instruction. + // + // Thus the list is chained as follows: + // + // ----> ----> ----> ----> ----> + // NONDEBUG NONDEBUG DEBUG DEBUG DEBUG NONDEBUG ... + // <---- ^ +-- <---- <---- ^ +-- + // | | | | + // | +------------------------+ | + // | | + // +-----------------------------------+ + using prev_insn_or_last_debug_insn = pointer_mux; + using next_nondebug_or_debug_insn = pointer_mux; + + insn_info (bb_info *bb, rtx_insn *rtl, int cost_or_uid); + + static void print_uid (pretty_printer *, int); + + void calculate_cost () const; + void set_properties (const rtx_properties &); + void set_accesses (access_info **, unsigned int, unsigned int); + void copy_accesses (access_array, access_array); + void set_cost (unsigned int cost) { m_cost_or_uid = cost; } + void set_bb (bb_info *bb) { m_bb = bb; } + + void add_note (insn_note *note); + + order_node *get_order_node () const; + order_node *get_known_order_node () const; + int slow_compare_with (const insn_info &) const; + + insn_info *last_debug_insn () const; + + unsigned int point () const { return m_point; } + void copy_prev_from (insn_info *); + void copy_next_from (insn_info *); + void set_prev_sametype_insn (insn_info *); + void set_last_debug_insn (insn_info *); + void set_next_any_insn (insn_info *); + void set_point (unsigned int point) { m_point = point; } + void clear_insn_links (); + bool has_insn_links (); + + // The values returned by the accessors above. + prev_insn_or_last_debug_insn m_prev_insn_or_last_debug_insn; + next_nondebug_or_debug_insn m_next_nondebug_or_debug_insn; + bb_info *m_bb; + rtx_insn *m_rtl; + + // The list of definitions followed by the list of uses. + access_info **m_accesses; + + // The number of definitions and the number uses. FIRST_PSEUDO_REGISTER + 1 + // is the maximum number of accesses to hard registers and memory, and + // MAX_RECOG_OPERANDS is the maximum number of pseudos that can be + // defined by an instruction, so the number of definitions should fit + // easily in 16 bits. + unsigned int m_num_uses; + unsigned int m_num_defs : 16; + + // Flags returned by the accessors above. + unsigned int m_is_debug_insn : 1; + unsigned int m_can_be_optimized : 1; + unsigned int m_is_asm : 1; + unsigned int m_has_pre_post_modify : 1; + unsigned int m_has_volatile_refs : 1; + + // For future expansion. + unsigned int m_spare : 11; + + // The program point at which the instruction occurs. + // + // Note that the values of the program points are influenced by -g + // and so should not used to make codegen decisions. + unsigned int m_point; + + // Negative if the instruction is artificial, nonnegative if it is real. + // + // For real instructions: the cost of the instruction, or UNKNOWN_COST + // if we haven't measured it yet. + // + // For artificial instructions: the (negative) unique identifier of the + // instruction. + mutable int m_cost_or_uid; + + // The list of notes that have been attached to the instruction. + insn_note *m_first_note; +}; + +// Iterators for unfiltered lists of instructions. +using any_insn_iterator = list_iterator; +using reverse_any_insn_iterator + = list_iterator; + +// Iterators for nondebug instructions only. +using nondebug_insn_iterator + = list_iterator; +using reverse_nondebug_insn_iterator + = list_iterator; + +// A class that describes an inclusive range of instructions. +class insn_range_info +{ +public: + insn_range_info () = default; + + // Create a range that contains a singleton instruction. + insn_range_info (insn_info *insn) : first (insn), last (insn) {} + + // Create a range [FIRST, LAST], given that *FIRST <= *LAST. + insn_range_info (insn_info *first, insn_info *last); + + // Return true if the range contains at least one instruction. + explicit operator bool () const { return *first <= *last; } + + bool operator== (const insn_range_info &) const; + bool operator!= (const insn_range_info &) const; + + // If the range contains a single instruction, return that instruction, + // otherwise return null. + insn_info *singleton () const; + + // Return true if the range includes INSN. + bool includes (insn_info *insn) const; + + // If INSN is inside the range, return INSN, otherwise return the + // nearest in-range instruction. + insn_info *clamp_insn_to_range (insn_info *insn) const; + + // Return true if this range is a subrange of OTHER, i.e. if OTHER + // includes every instruction that this range does. + bool is_subrange_of (const insn_range_info &other) const; + + // The lower and upper bounds of the range. + insn_info *first; + insn_info *last; +}; + +// A class that represents a closure of operator== for instructions. +// This is used by insn_is; see there for details. +class insn_is_closure +{ +public: + insn_is_closure (const insn_info *insn) : m_insn (insn) {} + bool operator() (const insn_info *other) const { return m_insn == other; } + +private: + const insn_info *m_insn; +}; + +void pp_insn (pretty_printer *, const insn_info *); + +} + +void dump (FILE *, const rtl_ssa::insn_info *); + +void DEBUG_FUNCTION debug (const rtl_ssa::insn_info *); diff --git a/gcc/rtl-ssa/internals.inl b/gcc/rtl-ssa/internals.inl new file mode 100644 index 0000000..00ad642 --- /dev/null +++ b/gcc/rtl-ssa/internals.inl @@ -0,0 +1,682 @@ +// Implementation of private inline member functions for RTL SSA -*- C++ -*- +// Copyright (C) 2020 Free Software Foundation, Inc. +// +// This file is part of GCC. +// +// GCC is free software; you can redistribute it and/or modify it under +// the terms of the GNU General Public License as published by the Free +// Software Foundation; either version 3, or (at your option) any later +// version. +// +// GCC is distributed in the hope that it will be useful, but WITHOUT ANY +// WARRANTY; without even the implied warranty of MERCHANTABILITY or +// FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License +// for more details. +// +// You should have received a copy of the GNU General Public License +// along with GCC; see the file COPYING3. If not see +// . + +namespace rtl_ssa { + +// Construct a new access with the given resource () and kind () values. +inline access_info::access_info (resource_info resource, access_kind kind) + : m_regno (resource.regno), + m_kind (kind), + m_is_artificial (false), + m_is_set_with_nondebug_insn_uses (false), + m_is_pre_post_modify (false), + m_is_call_clobber (false), + m_is_live_out_use (false), + m_includes_address_uses (false), + m_includes_read_writes (false), + m_includes_subregs (false), + m_includes_multiregs (false), + m_only_occurs_in_notes (false), + m_is_last_nondebug_insn_use (false), + m_is_in_debug_insn_or_phi (false), + m_has_been_superceded (false), + m_is_temp (false), + m_spare (0), + m_mode (resource.mode) +{ +} + +// Construct a use of RESOURCE in LOCATION. The resource's value is provided +// by DEF, or is completely undefined if DEF is null. +inline use_info::use_info (insn_or_phi location, resource_info resource, + set_info *definition) + : access_info (resource, access_kind::USE), + m_insn_or_phi (location), + m_last_use_or_prev_use (nullptr), + m_last_nondebug_insn_use_or_next_use (nullptr), + m_def (definition) +{ + if (m_insn_or_phi.is_second ()) + { + m_is_in_debug_insn_or_phi = true; + m_is_artificial = true; + } + else + { + insn_info *insn = m_insn_or_phi.known_first (); + m_is_in_debug_insn_or_phi = insn->is_debug_insn (); + m_is_artificial = insn->is_artificial (); + } +} + +// Return the correct (uncached) value of m_is_last_nondebug_insn_use. +inline bool +use_info::calculate_is_last_nondebug_insn_use () const +{ + use_info *next = next_use (); + return is_in_nondebug_insn () && (!next || next->is_in_debug_insn_or_phi ()); +} + +// Accumulate any properties about REF that are also stored in use_infos. +// IS_FIRST is true if REF is the first access to resource () that we have +// recorded in this way, false if we have already recorded previous +// references. +inline void +use_info::record_reference (rtx_obj_reference ref, bool is_first) +{ + if (is_first) + { + m_includes_address_uses = ref.in_address (); + m_includes_read_writes = ref.is_write (); + m_includes_subregs = ref.in_subreg (); + m_includes_multiregs = ref.is_multireg (); + m_only_occurs_in_notes = ref.in_note (); + } + else + { + m_includes_address_uses |= ref.in_address (); + m_includes_read_writes |= ref.is_write (); + m_includes_subregs |= ref.in_subreg (); + m_includes_multiregs |= ref.is_multireg (); + m_only_occurs_in_notes &= ref.in_note (); + } +} + +// Change the value of insn () to INSN. +inline void +use_info::set_insn (insn_info *insn) +{ + m_insn_or_phi = insn; + m_is_artificial = insn->is_artificial (); +} + +// Copy the overloaded prev link from OTHER. +inline void +use_info::copy_prev_from (use_info *other) +{ + m_last_use_or_prev_use = other->m_last_use_or_prev_use; +} + +// Copy the overloaded next link from OTHER. +inline void +use_info::copy_next_from (use_info *other) +{ + m_last_nondebug_insn_use_or_next_use + = other->m_last_nondebug_insn_use_or_next_use; + m_is_last_nondebug_insn_use = calculate_is_last_nondebug_insn_use (); +} + +// Record that this use is the first in the list and that the last use is LAST. +inline void +use_info::set_last_use (use_info *last_use) +{ + m_last_use_or_prev_use.set_first (last_use); +} + +// Record that this use is not the first in the list and that the previous +// use is PREV. +inline void +use_info::set_prev_use (use_info *prev_use) +{ + m_last_use_or_prev_use.set_second (prev_use); +} + +// Record that this use is the last use in the list. If USE is nonnull, +// record that USE is the last use in the list by a nondebug instruction, +// otherwise record that there are no uses by nondebug instructions +// in the list. +inline void +use_info::set_last_nondebug_insn_use (use_info *use) +{ + m_last_nondebug_insn_use_or_next_use.set_first (use); + m_is_last_nondebug_insn_use = (use == this); +} + +// Record that this use is not the last in the list and that the next +// use is NEXT_USE. +inline void +use_info::set_next_use (use_info *next_use) +{ + m_last_nondebug_insn_use_or_next_use.set_second (next_use); + m_is_last_nondebug_insn_use = calculate_is_last_nondebug_insn_use (); +} + +// Clear any information relating to the position of the use in its +// definition's list. +inline void +use_info::clear_use_links () +{ + m_last_use_or_prev_use = nullptr; + m_last_nondebug_insn_use_or_next_use = nullptr; + m_is_last_nondebug_insn_use = false; +} + +// Return true if the use has any links to other uses. This is mostly +// for assert checking. +inline bool +use_info::has_use_links () +{ + return (m_last_use_or_prev_use + || m_last_nondebug_insn_use_or_next_use + || m_is_last_nondebug_insn_use); +} + +// Construct a definition of RESOURCE in INSN, giving it kind KIND. +inline def_info::def_info (insn_info *insn, resource_info resource, + access_kind kind) + : access_info (resource, kind), + m_insn (insn), + m_last_def_or_prev_def (nullptr), + m_splay_root_or_next_def (nullptr) +{ + m_is_artificial = insn->is_artificial (); +} + +// Record any properties about REF that are also stored in def_infos. +// IS_FIRST is true if REF is the first access to resource () that we have +// recorded in this way, false if we have already recorded previous +// references. +inline void +def_info::record_reference (rtx_obj_reference ref, bool is_first) +{ + if (is_first) + { + m_is_pre_post_modify = ref.is_pre_post_modify (); + m_includes_read_writes = ref.is_read (); + m_includes_subregs = ref.in_subreg (); + m_includes_multiregs = ref.is_multireg (); + } + else + { + m_is_pre_post_modify |= ref.is_pre_post_modify (); + m_includes_read_writes |= ref.is_read (); + m_includes_subregs |= ref.in_subreg (); + m_includes_multiregs |= ref.is_multireg (); + } +} + +// Return the last definition in the list. Only valid when is_first () +// is true. +inline def_info * +def_info::last_def () const +{ + return m_last_def_or_prev_def.known_first (); +} + +// Return the root of the splay tree of definitions of resource (), +// or null if no splay tree has been created for this resource. +// Only valid when is_last () is true. +inline def_node * +def_info::splay_root () const +{ + return m_splay_root_or_next_def.known_first (); +} + +// Copy the overloaded prev link from OTHER. +inline void +def_info::copy_prev_from (def_info *other) +{ + m_last_def_or_prev_def + = other->m_last_def_or_prev_def; +} + +// Copy the overloaded next link from OTHER. +inline void +def_info::copy_next_from (def_info *other) +{ + m_splay_root_or_next_def = other->m_splay_root_or_next_def; +} + +// Record that this definition is the first in the list and that the last +// definition is LAST. +inline void +def_info::set_last_def (def_info *last_def) +{ + m_last_def_or_prev_def.set_first (last_def); +} + +// Record that this definition is not the first in the list and that the +// previous definition is PREV. +inline void +def_info::set_prev_def (def_info *prev_def) +{ + m_last_def_or_prev_def.set_second (prev_def); +} + +// Record that this definition is the last in the list and that the root +// of the splay tree associated with resource () is ROOT. +inline void +def_info::set_splay_root (def_node *root) +{ + m_splay_root_or_next_def = root; +} + +// Record that this definition is not the last in the list and that the +// next definition is NEXT. +inline void +def_info::set_next_def (def_info *next_def) +{ + m_splay_root_or_next_def = next_def; +} + +// Clear the prev and next links +inline void +def_info::clear_def_links () +{ + m_last_def_or_prev_def = nullptr; + m_splay_root_or_next_def = nullptr; +} + +// Return true if the definition has any links to other definitions. +// This is mostly for assert checking. +inline bool +def_info::has_def_links () +{ + return m_last_def_or_prev_def || m_splay_root_or_next_def; +} + +// Construct a clobber of register REGNO in insn INSN. +inline clobber_info::clobber_info (insn_info *insn, unsigned int regno) + : def_info (insn, { E_BLKmode, regno }, access_kind::CLOBBER), + m_children (), + m_parent (nullptr), + m_group (nullptr) +{ +} + +// Set the containing group to GROUP, if it isn't already. The main +// use of this function is to update the new root of GROUP's splay tree. +inline void +clobber_info::update_group (clobber_group *group) +{ + if (__builtin_expect (m_group != group, 0)) + m_group = group; +} + +// Cconstruct a set_info for a store to RESOURCE in INSN, giving it +// kind KIND. +inline set_info::set_info (insn_info *insn, resource_info resource, + access_kind kind) + : def_info (insn, resource, kind), + m_first_use (nullptr) +{ +} + +// Cconstruct a set_info for a store to RESOURCE in INSN. +inline set_info::set_info (insn_info *insn, resource_info resource) + : set_info (insn, resource, access_kind::SET) +{ +} + +// Record that USE is the first use of this definition. +inline void +set_info::set_first_use (use_info *first_use) +{ + m_first_use = first_use; + m_is_set_with_nondebug_insn_uses + = (first_use && first_use->is_in_nondebug_insn ()); +} + +// Construct a phi for RESOURCE in INSN, giving it identifier UID. +inline phi_info::phi_info (insn_info *insn, resource_info resource, + unsigned int uid) + : set_info (insn, resource, access_kind::PHI), + m_uid (uid), + m_num_inputs (0), + m_prev_phi (nullptr), + m_next_phi (nullptr) +{ +} + +// Turn the phi into a degenerate phi, with INPUT representing the +// value of the resource on all incoming edges. +inline void +phi_info::make_degenerate (use_info *input) +{ + m_num_inputs = 1; + m_single_input = input; +} + +// Set the inputs of the phi to INPUTS. +inline void +phi_info::set_inputs (use_array inputs) +{ + m_num_inputs = inputs.size (); + if (inputs.size () == 1) + m_single_input = inputs[0]; + else + m_inputs = access_array (inputs).begin (); +} + +// Construct a definition splay tree node for FIRST_DEF, which is either +// the first clobber_info in a group or a standalone set_info. +inline def_node::def_node (clobber_or_set first_def) + : m_clobber_or_set (first_def), + m_children () +{ +} + +// Construct a new group of clobber_infos that initially contains just CLOBBER. +inline clobber_group::clobber_group (clobber_info *clobber) + : def_node (clobber), + m_last_clobber (clobber), + m_clobber_tree (clobber) +{ + clobber->m_group = this; +} + +// Construct a node for the instruction with uid UID. +inline insn_info::order_node::order_node (int uid) + : insn_note (kind), + m_children (), + m_parent (nullptr) +{ + m_data32 = uid; +} + +// Construct a note for instruction INSN, giving it abi_id () value ABI_ID. +inline insn_call_clobbers_note::insn_call_clobbers_note (unsigned int abi_id, + insn_info *insn) + : insn_note (kind), + m_children (), + m_insn (insn) +{ + m_data32 = abi_id; +} + +// Construct an instruction with the given bb () and rtl () values. +// If the instruction is real, COST_OR_UID is the value of cost (), +// otherwise it is the value of uid (). +inline insn_info::insn_info (bb_info *bb, rtx_insn *rtl, int cost_or_uid) + : m_prev_insn_or_last_debug_insn (nullptr), + m_next_nondebug_or_debug_insn (nullptr), + m_bb (bb), + m_rtl (rtl), + m_accesses (nullptr), + m_num_uses (0), + m_num_defs (0), + m_is_debug_insn (rtl && DEBUG_INSN_P (rtl)), + m_can_be_optimized (false), + m_is_asm (false), + m_has_pre_post_modify (false), + m_has_volatile_refs (false), + m_spare (0), + m_point (0), + m_cost_or_uid (cost_or_uid), + m_first_note (nullptr) +{ +} + +// Copy any insn properties from PROPERTIES that are also stored in an +// insn_info. +inline void +insn_info::set_properties (const rtx_properties &properties) +{ + m_is_asm = properties.has_asm; + m_has_pre_post_modify = properties.has_pre_post_modify; + m_has_volatile_refs = properties.has_volatile_refs; + // Not strictly related to the properties we've been given, but it's + // a convenient location to do this. + m_can_be_optimized = (NONDEBUG_INSN_P (m_rtl) + & (GET_CODE (PATTERN (m_rtl)) != USE) + & (GET_CODE (PATTERN (m_rtl)) != CLOBBER)); +} + +// Change the list of instruction accesses to ACCESSES, which contains +// NUM_DEFS definitions followed by NUM_USES uses. +inline void +insn_info::set_accesses (access_info **accesses, + unsigned int num_defs, unsigned int num_uses) +{ + m_accesses = accesses; + m_num_defs = num_defs; + gcc_assert (num_defs == m_num_defs); + m_num_uses = num_uses; +} + +// Change defs () and uses () to DEFS and USES respectively, given that +// the existing m_accesses array has enough room for them. +inline void +insn_info::copy_accesses (access_array defs, access_array uses) +{ + gcc_assert (defs.size () + uses.size () <= m_num_defs + m_num_uses); + memcpy (m_accesses, defs.begin (), defs.size_bytes ()); + memcpy (m_accesses + defs.size (), uses.begin (), uses.size_bytes ()); + m_num_defs = defs.size (); + gcc_assert (m_num_defs == defs.size ()); + m_num_uses = uses.size (); +} + +// If the instruction has an insn_info::order_node, return the node, +// otherwise return null. +inline insn_info::order_node * +insn_info::get_order_node () const +{ + // The order_node always comes first. + if (insn_note *note = first_note ()) + return note->dyn_cast (); + return nullptr; +} + +// Like get_order_node (), but the node is known to exist. +inline insn_info::order_node * +insn_info::get_known_order_node () const +{ + // The order_node always comes first. + return first_note ()->as_a (); +} + +// Copy the overloaded prev link from OTHER. +inline void +insn_info::copy_prev_from (insn_info *other) +{ + m_prev_insn_or_last_debug_insn = other->m_prev_insn_or_last_debug_insn; +} + +// Copy the overloaded next link from OTHER. +inline void +insn_info::copy_next_from (insn_info *other) +{ + m_next_nondebug_or_debug_insn = other->m_next_nondebug_or_debug_insn; +} + +// If this is a nondebug instruction, record that the previous nondebug +// instruction is PREV. (There might be intervening debug instructions.) +// +// If this is a debug instruction, record that the previous instruction +// is debug instruction PREV. +inline void +insn_info::set_prev_sametype_insn (insn_info *prev) +{ + m_prev_insn_or_last_debug_insn.set_first (prev); +} + +// Only valid for debug instructions. Record that this instruction starts +// a subsequence of debug instructions that ends with LAST. +inline void +insn_info::set_last_debug_insn (insn_info *last) +{ + m_prev_insn_or_last_debug_insn.set_second (last); +} + +// Record that the next instruction of any kind is NEXT. +inline void +insn_info::set_next_any_insn (insn_info *next) +{ + if (next && next->is_debug_insn ()) + m_next_nondebug_or_debug_insn.set_second (next); + else + m_next_nondebug_or_debug_insn.set_first (next); +} + +// Clear the list links and point number for this instruction. +inline void +insn_info::clear_insn_links () +{ + m_prev_insn_or_last_debug_insn = nullptr; + m_next_nondebug_or_debug_insn = nullptr; + m_point = 0; +} + +// Return true if the instruction contains any list information. +// This is used by assert checking. +inline bool +insn_info::has_insn_links () +{ + return (m_prev_insn_or_last_debug_insn + || m_next_nondebug_or_debug_insn + || m_point); +} + +// Construct a representation of basic block CFG_BB. +inline bb_info::bb_info (basic_block cfg_bb) + : m_prev_bb (nullptr), + m_next_bb (nullptr), + m_cfg_bb (cfg_bb), + m_ebb (nullptr), + m_head_insn (nullptr), + m_end_insn (nullptr) +{ +} + +// Construct a tree of call clobbers for the given ABI. +inline ebb_call_clobbers_info:: +ebb_call_clobbers_info (const predefined_function_abi *abi) + : m_next (nullptr), + m_abi (abi) +{ +} + +// Construct an EBB whose first block is FIRST_BB and whose last block +// is LAST_BB. +inline ebb_info::ebb_info (bb_info *first_bb, bb_info *last_bb) + : m_first_phi (nullptr), + m_phi_insn (nullptr), + m_first_bb (first_bb), + m_last_bb (last_bb), + m_first_call_clobbers (nullptr) +{ +} + +// Set the contents of last_access for register REGNO to DEF. +inline void +function_info::build_info::record_reg_def (unsigned int regno, def_info *def) +{ + last_access[regno + 1] = def; +} + +// Set the contents of last_access for memory to DEF. +inline void +function_info::build_info::record_mem_def (def_info *def) +{ + last_access[0] = def; +} + +// Return the current value of live register REGNO, or null if the register's +// value is completedly undefined. +inline set_info * +function_info::build_info::current_reg_value (unsigned int regno) const +{ + return safe_dyn_cast (last_access[regno + 1]); +} + +// Return the current value of memory. +inline set_info * +function_info::build_info::current_mem_value () const +{ + return as_a (last_access[0]); +} + +// Allocate a T on the function's main obstack, passing ARGS +// to its constructor. +template +inline T * +function_info::allocate (Ts... args) +{ + static_assert (std::is_trivially_destructible::value, + "destructor won't be called"); + static_assert (alignof (T) <= obstack_alignment, + "too much alignment required"); + void *addr = obstack_alloc (&m_obstack, sizeof (T)); + return new (addr) T (std::forward (args)...); +} + +// Allocate a T on the function's temporary obstack, passing ARGS +// to its constructor. +template +inline T * +function_info::allocate_temp (Ts... args) +{ + static_assert (std::is_trivially_destructible::value, + "destructor won't be called"); + static_assert (alignof (T) <= obstack_alignment, + "too much alignment required"); + void *addr = obstack_alloc (&m_temp_obstack, sizeof (T)); + return new (addr) T (std::forward (args)...); +} + +// Add INSN to the end of the function's list of instructions. +inline void +function_info::append_insn (insn_info *insn) +{ + gcc_checking_assert (!insn->has_insn_links ()); + if (insn_info *after = m_last_insn) + add_insn_after (insn, after); + else + // The first instruction is for the entry block and is always a nondebug + // insn + m_first_insn = m_last_insn = m_last_nondebug_insn = insn; +} + +// Start building a new list of uses and definitions for an instruction. +inline void +function_info::start_insn_accesses () +{ + gcc_checking_assert (m_temp_defs.is_empty () + && m_temp_uses.is_empty ()); +} + +// Return a mode that encapsulates two distinct references to a register, +// one with mode MODE1 and one with mode MODE2. Treat BLKmode as a +// "don't know" wildcard. +inline machine_mode +combine_modes (machine_mode mode1, machine_mode mode2) +{ + if (mode1 == E_BLKmode) + return mode2; + + if (mode2 == E_BLKmode) + return mode1; + + return wider_subreg_mode (mode1, mode2); +} + +// PRINTER (PP, ARGS...) prints ARGS... to a pretty_printer PP. Use it +// to print ARGS... to FILE. +template +inline void +dump_using (FILE *file, Printer printer, Args... args) +{ + pretty_printer pp; + printer (&pp, args...); + pp_newline (&pp); + fprintf (file, "%s", pp_formatted_text (&pp)); +} + +} diff --git a/gcc/rtl-ssa/is-a.inl b/gcc/rtl-ssa/is-a.inl new file mode 100644 index 0000000..14e1316 --- /dev/null +++ b/gcc/rtl-ssa/is-a.inl @@ -0,0 +1,98 @@ +// is_a<> support for RTL SSA classes -*- C++ -*- +// Copyright (C) 2020 Free Software Foundation, Inc. +// +// This file is part of GCC. +// +// GCC is free software; you can redistribute it and/or modify it under +// the terms of the GNU General Public License as published by the Free +// Software Foundation; either version 3, or (at your option) any later +// version. +// +// GCC is distributed in the hope that it will be useful, but WITHOUT ANY +// WARRANTY; without even the implied warranty of MERCHANTABILITY or +// FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License +// for more details. +// +// You should have received a copy of the GNU General Public License +// along with GCC; see the file COPYING3. If not see +// . + +template<> +struct is_a_helper + : static_is_a_helper +{ + static inline bool + test (const rtl_ssa::access_info *ref) + { + return (ref->kind () == rtl_ssa::access_kind::SET + || ref->kind () == rtl_ssa::access_kind::PHI + || ref->kind () == rtl_ssa::access_kind::CLOBBER); + } +}; + +template<> +struct is_a_helper + : static_is_a_helper +{ + static inline bool + test (const rtl_ssa::access_info *ref) + { + return ref->kind () == rtl_ssa::access_kind::CLOBBER; + } +}; + +template<> +struct is_a_helper + : static_is_a_helper +{ + static inline bool + test (const rtl_ssa::access_info *ref) + { + return ref->kind () == rtl_ssa::access_kind::USE; + } +}; + +template<> +struct is_a_helper + : static_is_a_helper +{ + static inline bool + test (const rtl_ssa::access_info *ref) + { + return (ref->kind () == rtl_ssa::access_kind::SET + || ref->kind () == rtl_ssa::access_kind::PHI); + } +}; + +template<> +struct is_a_helper + : static_is_a_helper +{ + static inline bool + test (const rtl_ssa::access_info *ref) + { + return ref->kind () == rtl_ssa::access_kind::PHI; + } +}; + +template<> +struct is_a_helper + : static_is_a_helper +{ + static inline bool + test (const rtl_ssa::def_node *node) + { + return node->contains_set (); + } +}; + +template<> +struct is_a_helper + : static_is_a_helper +{ + static inline bool + test (const rtl_ssa::def_node *node) + { + return node->contains_clobber (); + } +}; diff --git a/gcc/rtl-ssa/member-fns.inl b/gcc/rtl-ssa/member-fns.inl new file mode 100644 index 0000000..4f3bb2e --- /dev/null +++ b/gcc/rtl-ssa/member-fns.inl @@ -0,0 +1,928 @@ +// Implementation of public inline member functions for RTL SSA -*- C++ -*- +// Copyright (C) 2020 Free Software Foundation, Inc. +// +// This file is part of GCC. +// +// GCC is free software; you can redistribute it and/or modify it under +// the terms of the GNU General Public License as published by the Free +// Software Foundation; either version 3, or (at your option) any later +// version. +// +// GCC is distributed in the hope that it will be useful, but WITHOUT ANY +// WARRANTY; without even the implied warranty of MERCHANTABILITY or +// FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License +// for more details. +// +// You should have received a copy of the GNU General Public License +// along with GCC; see the file COPYING3. If not see +// . + +// This file contains inline implementations of public member functions that +// are too large to be written in the class definition. It also contains +// some non-inline template definitions of public member functions. +// See the comments above the function declarations for details. +// +// The file also contains the bare minimum of private and protected inline +// member functions that are needed to make the public functions compile. +namespace rtl_ssa { + +inline void +access_array_builder::reserve (unsigned int num_accesses) +{ + obstack_make_room (m_obstack, num_accesses * sizeof (access_info *)); +} + +inline void +access_array_builder::quick_push (access_info *access) +{ + obstack_ptr_grow_fast (m_obstack, access); +} + +inline array_slice +access_array_builder::finish () +{ + auto num_accesses = obstack_object_size (m_obstack) / sizeof (access_info *); + if (num_accesses == 0) + return {}; + + auto **base = static_cast (obstack_finish (m_obstack)); + keep (); + return { base, num_accesses }; +} + +inline bool +access_info::is_set_with_nondebug_insn_uses () const +{ + return m_is_set_with_nondebug_insn_uses; +} + +inline bool +use_info::is_in_debug_insn () const +{ + return m_insn_or_phi.is_first () && m_is_in_debug_insn_or_phi; +} + +inline bb_info * +use_info::bb () const +{ + if (m_insn_or_phi.is_first ()) + return m_insn_or_phi.known_first ()->bb (); + return m_insn_or_phi.known_second ()->bb (); +} + +inline ebb_info * +use_info::ebb () const +{ + return bb ()->ebb (); +} + +inline use_info * +use_info::prev_use () const +{ + return m_last_use_or_prev_use.second_or_null (); +} + +inline use_info * +use_info::next_use () const +{ + return m_last_nondebug_insn_use_or_next_use.second_or_null (); +} + +inline bool +use_info::is_first_use () const +{ + return m_last_use_or_prev_use.is_first (); +} + +inline bool +use_info::is_last_use () const +{ + return m_last_nondebug_insn_use_or_next_use.is_first (); +} + +inline use_info * +use_info::next_nondebug_insn_use () const +{ + if (m_is_last_nondebug_insn_use) + return nullptr; + return m_last_nondebug_insn_use_or_next_use.known_second (); +} + +inline use_info * +use_info::next_any_insn_use () const +{ + // This is used less often than next_nondebug_insn_use, so it doesn't + // seem worth having an m_is_last_nondebug_insn_use-style end marker. + if (use_info *use = next_use ()) + if (use->is_in_any_insn ()) + return use; + return nullptr; +} + +inline use_info * +use_info::prev_phi_use () const +{ + // This is used less often than next_nondebug_insn_use, so it doesn't + // seem worth having an m_is_last_nondebug_insn_use-style end marker. + if (use_info *use = prev_use ()) + if (use->is_in_phi ()) + return use; + return nullptr; +} + +// Return the last use of any kind in the list. Only valid when is_first () +// is true. +inline use_info * +use_info::last_use () const +{ + return m_last_use_or_prev_use.known_first (); +} + +// Return the last nondebug insn use in the list, or null if none. Only valid +// when is_last_use () is true. +inline use_info * +use_info::last_nondebug_insn_use () const +{ + return m_last_nondebug_insn_use_or_next_use.known_first (); +} + +inline def_info * +def_info::prev_def () const +{ + return m_last_def_or_prev_def.second_or_null (); +} + +inline def_info * +def_info::next_def () const +{ + return m_splay_root_or_next_def.second_or_null (); +} + +inline bool +def_info::is_first_def () const +{ + return m_last_def_or_prev_def.is_first (); +} + +inline bool +def_info::is_last_def () const +{ + return m_splay_root_or_next_def.is_first (); +} + +inline bb_info * +def_info::bb () const +{ + return m_insn->bb (); +} + +inline ebb_info * +def_info::ebb () const +{ + return m_insn->ebb (); +} + +inline clobber_group * +clobber_info::group () const +{ + if (!m_group || !m_group->has_been_superceded ()) + return m_group; + return const_cast (this)->recompute_group (); +} + +inline use_info * +set_info::last_use () const +{ + return m_first_use ? m_first_use->last_use () : nullptr; +} + +inline use_info * +set_info::first_nondebug_insn_use () const +{ + if (m_is_set_with_nondebug_insn_uses) + return m_first_use; + return nullptr; +} + +inline use_info * +set_info::last_nondebug_insn_use () const +{ + if (m_is_set_with_nondebug_insn_uses) + return m_first_use->last_use ()->last_nondebug_insn_use (); + return nullptr; +} + +inline use_info * +set_info::first_any_insn_use () const +{ + if (m_first_use->is_in_any_insn ()) + return m_first_use; + return nullptr; +} + +inline use_info * +set_info::last_phi_use () const +{ + if (m_first_use) + { + use_info *last = m_first_use->last_use (); + if (last->is_in_phi ()) + return last; + } + return nullptr; +} + +inline bool +set_info::has_nondebug_uses () const +{ + return has_nondebug_insn_uses () || has_phi_uses (); +} + +inline bool +set_info::has_nondebug_insn_uses () const +{ + return m_is_set_with_nondebug_insn_uses; +} + +inline bool +set_info::has_phi_uses () const +{ + return m_first_use && m_first_use->last_use ()->is_in_phi (); +} + +inline bool +set_info::is_local_to_ebb () const +{ + if (!m_first_use) + return true; + + use_info *last = m_first_use->last_use (); + if (last->is_in_phi ()) + return false; + + last = last->last_nondebug_insn_use (); + return !last || last->ebb () == ebb (); +} + +inline iterator_range +set_info::all_uses () const +{ + return { m_first_use, nullptr }; +} + +inline iterator_range +set_info::reverse_all_uses () const +{ + return { last_use (), nullptr }; +} + +inline iterator_range +set_info::nondebug_insn_uses () const +{ + return { first_nondebug_insn_use (), nullptr }; +} + +inline iterator_range +set_info::reverse_nondebug_insn_uses () const +{ + return { last_nondebug_insn_use (), nullptr }; +} + +inline iterator_range +set_info::all_insn_uses () const +{ + return { first_any_insn_use (), nullptr }; +} + +inline iterator_range +set_info::phi_uses () const +{ + return { last_phi_use (), nullptr }; +} + +inline use_array +phi_info::inputs () const +{ + if (m_num_inputs == 1) + return use_array (&m_single_input, 1); + return use_array (m_inputs, m_num_inputs); +} + +inline use_info * +phi_info::input_use (unsigned int i) const +{ + if (m_num_inputs == 1) + return as_a (m_single_input); + return as_a (m_inputs[i]); +} + +inline set_info * +phi_info::input_value (unsigned int i) const +{ + return input_use (i)->def (); +} + +inline def_info * +def_node::first_def () const +{ + // This should get optimized into an AND with -2. + if (m_clobber_or_set.is_first ()) + return m_clobber_or_set.known_first (); + return m_clobber_or_set.known_second (); +} + +inline clobber_info * +clobber_group::first_clobber () const +{ + return m_clobber_or_set.known_first (); +} + +inline iterator_range +clobber_group::clobbers () const +{ + return { first_clobber (), m_last_clobber->next_def () }; +} + +inline def_info * +def_mux::first_def () const +{ + if (is_first ()) + return known_first (); + return known_second ()->first_def (); +} + +inline def_info * +def_mux::last_def () const +{ + if (is_first ()) + return known_first (); + + def_node *node = known_second (); + if (auto *clobber = ::dyn_cast (node)) + return clobber->last_clobber (); + + return node->first_def (); +} + +inline set_info * +def_mux::set () const +{ + if (is_first ()) + return ::safe_dyn_cast (known_first ()); + return ::dyn_cast (known_second ()->first_def ()); +} + +inline def_info * +def_lookup::prev_def () const +{ + if (!mux) + return nullptr; + + if (comparison > 0) + return mux.last_def (); + + return mux.first_def ()->prev_def (); +} + +inline def_info * +def_lookup::next_def () const +{ + if (!mux) + return nullptr; + + if (comparison < 0) + return mux.first_def (); + + return mux.last_def ()->next_def (); +} + +inline set_info * +def_lookup::matching_set () const +{ + if (comparison == 0) + return mux.set (); + return nullptr; +} + +inline def_info * +def_lookup::matching_or_prev_def () const +{ + if (set_info *set = matching_set ()) + return set; + return prev_def (); +} + +inline def_info * +def_lookup::matching_or_next_def () const +{ + if (set_info *set = matching_set ()) + return set; + return next_def (); +} + +inline insn_note::insn_note (insn_note_kind kind) + : m_next_note (nullptr), + m_kind (kind), + m_data8 (0), + m_data16 (0), + m_data32 (0) +{ +} + +template +inline T +insn_note::as_a () +{ + using deref_type = decltype (*std::declval ()); + using derived = typename std::remove_reference::type; + gcc_checking_assert (m_kind == derived::kind); + return static_cast (this); +} + +template +inline T +insn_note::dyn_cast () +{ + using deref_type = decltype (*std::declval ()); + using derived = typename std::remove_reference::type; + if (m_kind == derived::kind) + return static_cast (this); + return nullptr; +} + +inline bool +insn_info::operator< (const insn_info &other) const +{ + if (this == &other) + return false; + + if (__builtin_expect (m_point != other.m_point, 1)) + return m_point < other.m_point; + + return slow_compare_with (other) < 0; +} + +inline bool +insn_info::operator> (const insn_info &other) const +{ + return other < *this; +} + +inline bool +insn_info::operator<= (const insn_info &other) const +{ + return !(other < *this); +} + +inline bool +insn_info::operator>= (const insn_info &other) const +{ + return !(*this < other); +} + +inline int +insn_info::compare_with (const insn_info *other) const +{ + if (this == other) + return 0; + + if (__builtin_expect (m_point != other->m_point, 1)) + // Assume that points remain in [0, INT_MAX]. + return m_point - other->m_point; + + return slow_compare_with (*other); +} + +inline insn_info * +insn_info::prev_nondebug_insn () const +{ + gcc_checking_assert (!is_debug_insn ()); + return m_prev_insn_or_last_debug_insn.known_first (); +} + +inline insn_info * +insn_info::next_nondebug_insn () const +{ + gcc_checking_assert (!is_debug_insn ()); + const insn_info *from = this; + if (insn_info *first_debug = m_next_nondebug_or_debug_insn.second_or_null ()) + from = first_debug->last_debug_insn (); + return from->m_next_nondebug_or_debug_insn.known_first (); +} + +inline insn_info * +insn_info::prev_any_insn () const +{ + const insn_info *from = this; + if (insn_info *last_debug = m_prev_insn_or_last_debug_insn.second_or_null ()) + // This instruction is the first in a subsequence of debug instructions. + // Move to the following nondebug instruction. + from = last_debug->m_next_nondebug_or_debug_insn.known_first (); + return from->m_prev_insn_or_last_debug_insn.known_first (); +} + +inline insn_info * +insn_info::next_any_insn () const +{ + // This should get optimized into an AND with -2. + if (m_next_nondebug_or_debug_insn.is_first ()) + return m_next_nondebug_or_debug_insn.known_first (); + return m_next_nondebug_or_debug_insn.known_second (); +} + +inline bool +insn_info::is_phi () const +{ + return this == ebb ()->phi_insn (); +} + +inline bool +insn_info::is_bb_head () const +{ + return this == m_bb->head_insn (); +} + +inline bool +insn_info::is_bb_end () const +{ + return this == m_bb->end_insn (); +} + +inline ebb_info * +insn_info::ebb () const +{ + return m_bb->ebb (); +} + +inline int +insn_info::uid () const +{ + return m_cost_or_uid < 0 ? m_cost_or_uid : INSN_UID (m_rtl); +} + +inline use_array +insn_info::uses () const +{ + return use_array (m_accesses + m_num_defs, m_num_uses); +} + +inline bool +insn_info::has_call_clobbers () const +{ + return find_note (); +} + +inline def_array +insn_info::defs () const +{ + return def_array (m_accesses, m_num_defs); +} + +inline unsigned int +insn_info::cost () const +{ + if (m_cost_or_uid < 0) + return 0; + if (m_cost_or_uid == UNKNOWN_COST) + calculate_cost (); + return m_cost_or_uid; +} + +template +inline const T * +insn_info::find_note () const +{ + // We could break if the note kind is > T::kind, but since the number + // of notes should be very small, the check is unlikely to pay for itself. + for (const insn_note *note = first_note (); note; note = note->next_note ()) + if (note->kind () == T::kind) + return static_cast (note); + return nullptr; +} + +// Only valid for debug instructions that come after a nondebug instruction, +// and so start a subsequence of debug instructions. Return the last debug +// instruction in the subsequence. +inline insn_info * +insn_info::last_debug_insn () const +{ + return m_prev_insn_or_last_debug_insn.known_second (); +} + +inline insn_range_info::insn_range_info (insn_info *first, insn_info *last) + : first (first), last (last) +{ +} + +inline bool +insn_range_info::operator== (const insn_range_info &other) const +{ + return first == other.first && last == other.last; +} + +inline bool +insn_range_info::operator!= (const insn_range_info &other) const +{ + return first != other.first || last != other.last; +} + +inline insn_info * +insn_range_info::singleton () const +{ + return first == last ? last : nullptr; +} + +inline bool +insn_range_info::includes (insn_info *insn) const +{ + return *insn >= *first && *insn <= *last; +} + +inline insn_info * +insn_range_info::clamp_insn_to_range (insn_info *insn) const +{ + if (*first > *insn) + return first; + if (*last < *insn) + return last; + return insn; +} + +inline bool +insn_range_info::is_subrange_of (const insn_range_info &other) const +{ + return *first >= *other.first && *last <= *other.last; +} + +inline iterator_range +bb_info::all_insns () const +{ + return { m_head_insn, m_end_insn->next_any_insn () }; +} + +inline iterator_range +bb_info::reverse_all_insns () const +{ + return { m_end_insn, m_head_insn->prev_any_insn () }; +} + +inline iterator_range +bb_info::nondebug_insns () const +{ + return { m_head_insn, m_end_insn->next_nondebug_insn () }; +} + +inline iterator_range +bb_info::reverse_nondebug_insns () const +{ + return { m_end_insn, m_head_insn->prev_nondebug_insn () }; +} + +inline iterator_range +bb_info::real_insns () const +{ + return { m_head_insn->next_any_insn (), m_end_insn }; +} + +inline iterator_range +bb_info::reverse_real_insns () const +{ + return { m_end_insn->prev_any_insn (), m_head_insn }; +} + +inline iterator_range +bb_info::real_nondebug_insns () const +{ + return { m_head_insn->next_nondebug_insn (), m_end_insn }; +} + +inline iterator_range +bb_info::reverse_real_nondebug_insns () const +{ + return { m_end_insn->prev_nondebug_insn (), m_head_insn }; +} + +inline bool +ebb_call_clobbers_info::clobbers (resource_info resource) const +{ + // Only register clobbers are tracked this way. Other clobbers are + // recorded explicitly. + return (resource.is_reg () + && m_abi->clobbers_reg_p (resource.mode, resource.regno)); +} + +inline ebb_info * +ebb_info::prev_ebb () const +{ + if (bb_info *prev_bb = m_first_bb->prev_bb ()) + return prev_bb->ebb (); + return nullptr; +} + +inline ebb_info * +ebb_info::next_ebb () const +{ + if (bb_info *next_bb = m_last_bb->next_bb ()) + return next_bb->ebb (); + return nullptr; +} + +inline iterator_range +ebb_info::phis () const +{ + return { m_first_phi, nullptr }; +} + +inline iterator_range +ebb_info::bbs () const +{ + return { m_first_bb, m_last_bb->next_bb () }; +} + +inline iterator_range +ebb_info::reverse_bbs () const +{ + return { m_last_bb, m_first_bb->prev_bb () }; +} + +inline iterator_range +ebb_info::all_insns () const +{ + return { m_phi_insn, m_last_bb->end_insn ()->next_any_insn () }; +} + +inline iterator_range +ebb_info::reverse_all_insns () const +{ + return { m_last_bb->end_insn (), m_phi_insn->prev_any_insn () }; +} + +inline iterator_range +ebb_info::nondebug_insns () const +{ + return { m_phi_insn, m_last_bb->end_insn ()->next_nondebug_insn () }; +} + +inline iterator_range +ebb_info::reverse_nondebug_insns () const +{ + return { m_last_bb->end_insn (), m_phi_insn->prev_nondebug_insn () }; +} + +inline insn_range_info +ebb_info::insn_range () const +{ + return { m_phi_insn, m_last_bb->end_insn () }; +} + +inline void +ebb_info::set_first_call_clobbers (ebb_call_clobbers_info *call_clobbers) +{ + m_first_call_clobbers = call_clobbers; +} + +inline ebb_call_clobbers_info * +ebb_info::first_call_clobbers () const +{ + return m_first_call_clobbers; +} + +inline iterator_range +ebb_info::call_clobbers () const +{ + return { m_first_call_clobbers, nullptr }; +} + +inline insn_change::insn_change (insn_info *insn) + : m_insn (insn), + new_defs (insn->defs ()), + new_uses (insn->uses ()), + move_range (insn), + new_cost (UNKNOWN_COST), + m_is_deletion (false) +{ +} + +inline insn_change::insn_change (insn_info *insn, delete_action) + : m_insn (insn), + new_defs (), + new_uses (), + move_range (insn), + new_cost (0), + m_is_deletion (true) +{ +} + +inline insn_is_changing_closure:: +insn_is_changing_closure (array_slice changes) + : m_changes (changes) +{ +} + +inline bool +insn_is_changing_closure::operator() (const insn_info *insn) const +{ + for (const insn_change *change : m_changes) + if (change->insn () == insn) + return true; + return false; +} + +inline iterator_range +function_info::bbs () const +{ + return { m_first_bb, nullptr }; +} + +inline iterator_range +function_info::reverse_bbs () const +{ + return { m_last_bb, nullptr }; +} + +inline iterator_range +function_info::ebbs () const +{ + return { m_first_bb->ebb (), nullptr }; +} + +inline iterator_range +function_info::reverse_ebbs () const +{ + return { m_last_bb->ebb (), nullptr }; +} + +inline iterator_range +function_info::all_insns () const +{ + return { m_first_insn, nullptr }; +} + +inline iterator_range +function_info::reverse_all_insns () const +{ + return { m_last_insn, nullptr }; +} + +inline iterator_range +function_info::nondebug_insns () const +{ + return { m_first_insn, nullptr }; +} + +inline iterator_range +function_info::reverse_nondebug_insns () const +{ + return { m_last_insn, nullptr }; +} + +inline iterator_range +function_info::mem_defs () const +{ + return { m_defs[0], nullptr }; +} + +inline iterator_range +function_info::ref_defs (unsigned int regno) const +{ + return { m_defs[regno + 1], nullptr }; +} + +inline set_info * +function_info::single_dominating_def (unsigned int regno) const +{ + if (set_info *set = safe_dyn_cast (m_defs[regno + 1])) + if (is_single_dominating_def (set)) + return set; + return nullptr; +} + +template +bool +function_info::add_regno_clobber (obstack_watermark &watermark, + insn_change &change, unsigned int regno, + IgnorePredicate ignore) +{ + // Check whether CHANGE already clobbers REGNO. + if (find_access (change.new_defs, regno)) + return true; + + // Get the closest position to INSN at which the new instruction + // could be placed. + insn_info *insn = change.move_range.clamp_insn_to_range (change.insn ()); + def_array new_defs = insert_temp_clobber (watermark, insn, regno, + change.new_defs); + if (!new_defs.is_valid ()) + return false; + + // Find a definition at or neighboring INSN. + insn_range_info move_range = change.move_range; + if (!restrict_movement_for_dead_range (move_range, regno, insn, ignore)) + return false; + + change.new_defs = new_defs; + change.move_range = move_range; + return true; +} + +} diff --git a/gcc/rtl-ssa/movement.h b/gcc/rtl-ssa/movement.h new file mode 100644 index 0000000..3b0cbf9 --- /dev/null +++ b/gcc/rtl-ssa/movement.h @@ -0,0 +1,335 @@ +// RTL SSA utilities relating to instruction movement -*- C++ -*- +// Copyright (C) 2020 Free Software Foundation, Inc. +// +// This file is part of GCC. +// +// GCC is free software; you can redistribute it and/or modify it under +// the terms of the GNU General Public License as published by the Free +// Software Foundation; either version 3, or (at your option) any later +// version. +// +// GCC is distributed in the hope that it will be useful, but WITHOUT ANY +// WARRANTY; without even the implied warranty of MERCHANTABILITY or +// FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License +// for more details. +// +// You should have received a copy of the GNU General Public License +// along with GCC; see the file COPYING3. If not see +// . + +namespace rtl_ssa { + +// Restrict movement range RANGE so that the instruction is placed later +// than INSN. (The movement range is the range of instructions after which +// an instruction can be placed.) +inline insn_range_info +move_later_than (insn_range_info range, insn_info *insn) +{ + return { later_insn (range.first, insn), range.last }; +} + +// Restrict movement range RANGE so that the instruction is placed no earlier +// than INSN. (The movement range is the range of instructions after which +// an instruction can be placed.) +inline insn_range_info +move_no_earlier_than (insn_range_info range, insn_info *insn) +{ + insn_info *first = later_insn (range.first, insn->prev_nondebug_insn ()); + return { first, range.last }; +} + +// Restrict movement range RANGE so that the instruction is placed no later +// than INSN. (The movement range is the range of instructions after which +// an instruction can be placed.) +inline insn_range_info +move_no_later_than (insn_range_info range, insn_info *insn) +{ + return { range.first, earlier_insn (range.last, insn) }; +} + +// Restrict movement range RANGE so that the instruction is placed earlier +// than INSN. (The movement range is the range of instructions after which +// an instruction can be placed.) +inline insn_range_info +move_earlier_than (insn_range_info range, insn_info *insn) +{ + insn_info *last = earlier_insn (range.last, insn->prev_nondebug_insn ()); + return { range.first, last }; +} + +// Return true if it is possible to insert a new instruction after INSN. +inline bool +can_insert_after (insn_info *insn) +{ + return insn->is_bb_head () || (insn->is_real () && !insn->is_jump ()); +} + +// Try to restrict move range MOVE_RANGE so that it is possible to +// insert INSN after both of the end points. Return true on success, +// otherwise leave MOVE_RANGE in an invalid state. +inline bool +canonicalize_move_range (insn_range_info &move_range, insn_info *insn) +{ + while (move_range.first != insn && !can_insert_after (move_range.first)) + move_range.first = move_range.first->next_nondebug_insn (); + while (move_range.last != insn && !can_insert_after (move_range.last)) + move_range.last = move_range.last->prev_nondebug_insn (); + return bool (move_range); +} + +// Try to restrict movement range MOVE_RANGE of INSN so that it can set +// or clobber REGNO. Assume that if: +// +// - an instruction I2 contains another access A to REGNO; and +// - IGNORE (I2) is true +// +// then either: +// +// - A will be removed; or +// - something will ensure that the new definition of REGNO does not +// interfere with A, without this having to be enforced by I1's move range. +// +// Return true on success, otherwise leave MOVE_RANGE in an invalid state. +// +// This function only works correctly for instructions that remain within +// the same extended basic block. +template +bool +restrict_movement_for_dead_range (insn_range_info &move_range, + unsigned int regno, insn_info *insn, + IgnorePredicate ignore) +{ + // Find a definition at or neighboring INSN. + resource_info resource = full_register (regno); + def_lookup dl = crtl->ssa->find_def (resource, insn); + + def_info *prev = dl.prev_def (); + ebb_info *ebb = insn->ebb (); + if (!prev || prev->ebb () != ebb) + { + // REGNO is not defined or used in EBB before INSN, but it + // might be live on entry. To keep complexity under control, + // handle only these cases: + // + // - If the register is not live on entry to EBB, the register is + // free from the start of EBB to the first definition in EBB. + // + // - Otherwise, if the register is live on entry to BB, refuse + // to allocate the register. We could in principle try to move + // the instruction to later blocks in the EBB, but it's rarely + // worth the effort, and could lead to linear complexity. + // + // - Otherwise, don't allow INSN to move earlier than its current + // block. Again, we could in principle look backwards to find where + // REGNO dies, but it's rarely worth the effort. + bb_info *bb = insn->bb (); + insn_info *limit; + if (!bitmap_bit_p (DF_LR_IN (ebb->first_bb ()->cfg_bb ()), regno)) + limit = ebb->phi_insn (); + else if (bitmap_bit_p (DF_LR_IN (bb->cfg_bb ()), regno)) + return false; + else + limit = bb->head_insn (); + move_range = move_later_than (move_range, limit); + } + else + { + // Stop the instruction moving beyond the previous relevant access + // to REGNO. + access_info *prev_access + = last_access_ignoring (prev, ignore_clobbers::YES, ignore); + if (prev_access) + move_range = move_later_than (move_range, access_insn (prev_access)); + } + + // Stop the instruction moving beyond the next relevant definition of REGNO. + def_info *next = first_def_ignoring (dl.matching_or_next_def (), + ignore_clobbers::YES, ignore); + if (next) + move_range = move_earlier_than (move_range, next->insn ()); + + return canonicalize_move_range (move_range, insn); +} + +// Try to restrict movement range MOVE_RANGE so that it is possible for the +// instruction being moved ("instruction I1") to perform all the definitions +// in DEFS while still preserving dependencies between those definitions +// and surrounding instructions. Assume that if: +// +// - DEFS contains a definition D of resource R; +// - an instruction I2 contains another access A to R; and +// - IGNORE (I2) is true +// +// then either: +// +// - A will be removed; or +// - something will ensure that D and A maintain their current order, +// without this having to be enforced by I1's move range. +// +// Return true on success, otherwise leave MOVE_RANGE in an invalid state. +// +// This function only works correctly for instructions that remain within +// the same extended basic block. +template +bool +restrict_movement_for_defs_ignoring (insn_range_info &move_range, + def_array defs, IgnorePredicate ignore) +{ + for (def_info *def : defs) + { + // If the definition is a clobber, we can move it with respect + // to other clobbers. + // + // ??? We could also do this if a definition and all its uses + // are being moved at once. + bool is_clobber = is_a (def); + + // Search back for the first unfiltered use or definition of the + // same resource. + access_info *access; + access = prev_access_ignoring (def, ignore_clobbers (is_clobber), + ignore); + if (access) + move_range = move_later_than (move_range, access_insn (access)); + + // Search forward for the first unfiltered use of DEF, + // or the first unfiltered definition that follows DEF. + // + // We don't need to consider uses of following definitions, since + // if IGNORE (D->insn ()) is true for some definition D, the caller + // is guarantees that either + // + // - D will be removed, and thus its uses will be removed; or + // - D will occur after DEF, and thus D's uses will also occur + // after DEF. + // + // This is purely a simplification: we could also process D's uses, + // but we don't need to. + access = next_access_ignoring (def, ignore_clobbers (is_clobber), + ignore); + if (access) + move_range = move_earlier_than (move_range, access_insn (access)); + + // If DEF sets a hard register, take any call clobbers + // into account. + unsigned int regno = def->regno (); + if (!HARD_REGISTER_NUM_P (regno) || is_clobber) + continue; + + ebb_info *ebb = def->ebb (); + for (ebb_call_clobbers_info *call_group : ebb->call_clobbers ()) + { + if (!call_group->clobbers (def->resource ())) + continue; + + // Exit now if we've already failed, and if the splay accesses + // below would be wasted work. + if (!move_range) + return false; + + insn_info *insn; + insn = prev_call_clobbers_ignoring (*call_group, def->insn (), + ignore); + if (insn) + move_range = move_later_than (move_range, insn); + + insn = next_call_clobbers_ignoring (*call_group, def->insn (), + ignore); + if (insn) + move_range = move_earlier_than (move_range, insn); + } + } + + // Make sure that we don't move stores between basic blocks, since we + // don't have enough information to tell whether it's safe. + if (def_info *def = memory_access (defs)) + { + move_range = move_later_than (move_range, def->bb ()->head_insn ()); + move_range = move_earlier_than (move_range, def->bb ()->end_insn ()); + } + + return bool (move_range); +} + +// Like restrict_movement_for_defs_ignoring, but for the uses in USES. +template +bool +restrict_movement_for_uses_ignoring (insn_range_info &move_range, + use_array uses, IgnorePredicate ignore) +{ + for (const use_info *use : uses) + { + // Ignore uses of undefined values. + set_info *set = use->def (); + if (!set) + continue; + + // Ignore uses by debug instructions. Debug instructions are + // never supposed to move, and uses by debug instructions are + // never supposed to be transferred elsewhere, so we know that + // the caller must be changing the uses on the debug instruction + // and checking whether all new uses are available at the debug + // instruction's original location. + if (use->is_in_debug_insn ()) + continue; + + // If the used value is defined by an instruction I2 for which + // IGNORE (I2) is true, the caller guarantees that I2 will occur + // before change.insn (). Otherwise, make sure that the use occurs + // after the definition. + insn_info *insn = set->insn (); + if (!ignore (insn)) + move_range = move_later_than (move_range, insn); + + // Search forward for the first unfiltered definition that follows SET. + // + // We don't need to consider the uses of these definitions, since + // if IGNORE (D->insn ()) is true for some definition D, the caller + // is guarantees that either + // + // - D will be removed, and thus its uses will be removed; or + // - D will occur after USE, and thus D's uses will also occur + // after USE. + // + // This is purely a simplification: we could also process D's uses, + // but we don't need to. + def_info *def; + def = first_def_ignoring (set->next_def (), ignore_clobbers::NO, + ignore); + if (def) + move_range = move_earlier_than (move_range, def->insn ()); + + // If USE uses a hard register, take any call clobbers into account too. + // SET will necessarily occur after any previous call clobber, so we + // only need to check for later clobbers. + unsigned int regno = use->regno (); + if (!HARD_REGISTER_NUM_P (regno)) + continue; + + ebb_info *ebb = use->ebb (); + for (ebb_call_clobbers_info *call_group : ebb->call_clobbers ()) + { + if (!call_group->clobbers (use->resource ())) + continue; + + if (!move_range) + return false; + + insn_info *insn = next_call_clobbers_ignoring (*call_group, + use->insn (), ignore); + if (insn) + move_range = move_earlier_than (move_range, insn); + } + } + + // Make sure that we don't move loads into an earlier basic block. + // + // ??? It would be good to relax this for loads that can be safely + // speculated. + if (use_info *use = memory_access (uses)) + move_range = move_later_than (move_range, use->bb ()->head_insn ()); + + return bool (move_range); +} + +} diff --git a/gcc/system.h b/gcc/system.h index 8ec04f0..5b42825 100644 --- a/gcc/system.h +++ b/gcc/system.h @@ -235,6 +235,9 @@ extern int errno; #ifdef INCLUDE_ARRAY # include #endif +#ifdef INCLUDE_FUNCTIONAL +# include +#endif # include # include # include