1 /* Data flow analysis for GNU compiler.
2 Copyright (C) 1987, 1988, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
3 1999, 2000, 2001 Free Software Foundation, Inc.
5 This file is part of GNU CC.
7 GNU CC is free software; you can redistribute it and/or modify
8 it under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 2, or (at your option)
12 GNU CC is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU General Public License for more details.
17 You should have received a copy of the GNU General Public License
18 along with GNU CC; see the file COPYING. If not, write to
19 the Free Software Foundation, 59 Temple Place - Suite 330,
20 Boston, MA 02111-1307, USA. */
22 /* This file contains the data flow analysis pass of the compiler. It
23 computes data flow information which tells combine_instructions
24 which insns to consider combining and controls register allocation.
26 Additional data flow information that is too bulky to record is
27 generated during the analysis, and is used at that time to create
28 autoincrement and autodecrement addressing.
30 The first step is dividing the function into basic blocks.
31 find_basic_blocks does this. Then life_analysis determines
32 where each register is live and where it is dead.
34 ** find_basic_blocks **
36 find_basic_blocks divides the current function's rtl into basic
37 blocks and constructs the CFG. The blocks are recorded in the
38 basic_block_info array; the CFG exists in the edge structures
39 referenced by the blocks.
41 find_basic_blocks also finds any unreachable loops and deletes them.
45 life_analysis is called immediately after find_basic_blocks.
46 It uses the basic block information to determine where each
47 hard or pseudo register is live.
49 ** live-register info **
51 The information about where each register is live is in two parts:
52 the REG_NOTES of insns, and the vector basic_block->global_live_at_start.
54 basic_block->global_live_at_start has an element for each basic
55 block, and the element is a bit-vector with a bit for each hard or
56 pseudo register. The bit is 1 if the register is live at the
57 beginning of the basic block.
59 Two types of elements can be added to an insn's REG_NOTES.
60 A REG_DEAD note is added to an insn's REG_NOTES for any register
61 that meets both of two conditions: The value in the register is not
62 needed in subsequent insns and the insn does not replace the value in
63 the register (in the case of multi-word hard registers, the value in
64 each register must be replaced by the insn to avoid a REG_DEAD note).
66 In the vast majority of cases, an object in a REG_DEAD note will be
67 used somewhere in the insn. The (rare) exception to this is if an
68 insn uses a multi-word hard register and only some of the registers are
69 needed in subsequent insns. In that case, REG_DEAD notes will be
70 provided for those hard registers that are not subsequently needed.
71 Partial REG_DEAD notes of this type do not occur when an insn sets
72 only some of the hard registers used in such a multi-word operand;
73 omitting REG_DEAD notes for objects stored in an insn is optional and
74 the desire to do so does not justify the complexity of the partial
77 REG_UNUSED notes are added for each register that is set by the insn
78 but is unused subsequently (if every register set by the insn is unused
79 and the insn does not reference memory or have some other side-effect,
80 the insn is deleted instead). If only part of a multi-word hard
81 register is used in a subsequent insn, REG_UNUSED notes are made for
82 the parts that will not be used.
84 To determine which registers are live after any insn, one can
85 start from the beginning of the basic block and scan insns, noting
86 which registers are set by each insn and which die there.
88 ** Other actions of life_analysis **
90 life_analysis sets up the LOG_LINKS fields of insns because the
91 information needed to do so is readily available.
93 life_analysis deletes insns whose only effect is to store a value
96 life_analysis notices cases where a reference to a register as
97 a memory address can be combined with a preceding or following
98 incrementation or decrementation of the register. The separate
99 instruction to increment or decrement is deleted and the address
100 is changed to a POST_INC or similar rtx.
102 Each time an incrementing or decrementing address is created,
103 a REG_INC element is added to the insn's REG_NOTES list.
105 life_analysis fills in certain vectors containing information about
106 register usage: REG_N_REFS, REG_N_DEATHS, REG_N_SETS, REG_LIVE_LENGTH,
107 REG_N_CALLS_CROSSED and REG_BASIC_BLOCK.
109 life_analysis sets current_function_sp_is_unchanging if the function
110 doesn't modify the stack pointer. */
114 Split out from life_analysis:
115 - local property discovery (bb->local_live, bb->local_set)
116 - global property computation
118 - pre/post modify transformation
126 #include "hard-reg-set.h"
127 #include "basic-block.h"
128 #include "insn-config.h"
132 #include "function.h"
140 #include "splay-tree.h"
142 #define obstack_chunk_alloc xmalloc
143 #define obstack_chunk_free free
145 /* EXIT_IGNORE_STACK should be nonzero if, when returning from a function,
146 the stack pointer does not matter. The value is tested only in
147 functions that have frame pointers.
148 No definition is equivalent to always zero. */
149 #ifndef EXIT_IGNORE_STACK
150 #define EXIT_IGNORE_STACK 0
153 #ifndef HAVE_epilogue
154 #define HAVE_epilogue 0
156 #ifndef HAVE_prologue
157 #define HAVE_prologue 0
159 #ifndef HAVE_sibcall_epilogue
160 #define HAVE_sibcall_epilogue 0
164 #define LOCAL_REGNO(REGNO) 0
166 #ifndef EPILOGUE_USES
167 #define EPILOGUE_USES(REGNO) 0
170 #ifdef HAVE_conditional_execution
171 #ifndef REVERSE_CONDEXEC_PREDICATES_P
172 #define REVERSE_CONDEXEC_PREDICATES_P(x, y) ((x) == reverse_condition (y))
176 /* The obstack on which the flow graph components are allocated. */
178 struct obstack flow_obstack;
179 static char *flow_firstobj;
181 /* Number of basic blocks in the current function. */
185 /* Number of edges in the current function. */
189 /* The basic block array. */
191 varray_type basic_block_info;
193 /* The special entry and exit blocks. */
195 struct basic_block_def entry_exit_blocks[2]
200 NULL, /* local_set */
201 NULL, /* cond_local_set */
202 NULL, /* global_live_at_start */
203 NULL, /* global_live_at_end */
205 ENTRY_BLOCK, /* index */
215 NULL, /* local_set */
216 NULL, /* cond_local_set */
217 NULL, /* global_live_at_start */
218 NULL, /* global_live_at_end */
220 EXIT_BLOCK, /* index */
227 /* Nonzero if the second flow pass has completed. */
230 /* Maximum register number used in this function, plus one. */
234 /* Indexed by n, giving various register information */
236 varray_type reg_n_info;
238 /* Size of a regset for the current function,
239 in (1) bytes and (2) elements. */
244 /* Regset of regs live when calls to `setjmp'-like functions happen. */
245 /* ??? Does this exist only for the setjmp-clobbered warning message? */
247 regset regs_live_at_setjmp;
249 /* List made of EXPR_LIST rtx's which gives pairs of pseudo registers
250 that have to go in the same hard reg.
251 The first two regs in the list are a pair, and the next two
252 are another pair, etc. */
255 /* Callback that determines if it's ok for a function to have no
256 noreturn attribute. */
257 int (*lang_missing_noreturn_ok_p) PARAMS ((tree));
259 /* Set of registers that may be eliminable. These are handled specially
260 in updating regs_ever_live. */
262 static HARD_REG_SET elim_reg_set;
264 /* The basic block structure for every insn, indexed by uid. */
266 varray_type basic_block_for_insn;
268 /* The labels mentioned in non-jump rtl. Valid during find_basic_blocks. */
269 /* ??? Should probably be using LABEL_NUSES instead. It would take a
270 bit of surgery to be able to use or co-opt the routines in jump. */
272 static rtx label_value_list;
273 static rtx tail_recursion_label_list;
275 /* Holds information for tracking conditional register life information. */
276 struct reg_cond_life_info
278 /* A boolean expression of conditions under which a register is dead. */
280 /* Conditions under which a register is dead at the basic block end. */
283 /* A boolean expression of conditions under which a register has been
287 /* ??? Could store mask of bytes that are dead, so that we could finally
288 track lifetimes of multi-word registers accessed via subregs. */
291 /* For use in communicating between propagate_block and its subroutines.
292 Holds all information needed to compute life and def-use information. */
294 struct propagate_block_info
296 /* The basic block we're considering. */
299 /* Bit N is set if register N is conditionally or unconditionally live. */
302 /* Bit N is set if register N is set this insn. */
305 /* Element N is the next insn that uses (hard or pseudo) register N
306 within the current basic block; or zero, if there is no such insn. */
309 /* Contains a list of all the MEMs we are tracking for dead store
313 /* If non-null, record the set of registers set unconditionally in the
317 /* If non-null, record the set of registers set conditionally in the
319 regset cond_local_set;
321 #ifdef HAVE_conditional_execution
322 /* Indexed by register number, holds a reg_cond_life_info for each
323 register that is not unconditionally live or dead. */
324 splay_tree reg_cond_dead;
326 /* Bit N is set if register N is in an expression in reg_cond_dead. */
330 /* The length of mem_set_list. */
331 int mem_set_list_len;
333 /* Non-zero if the value of CC0 is live. */
336 /* Flags controling the set of information propagate_block collects. */
340 /* Maximum length of pbi->mem_set_list before we start dropping
341 new elements on the floor. */
342 #define MAX_MEM_SET_LIST_LEN 100
344 /* Store the data structures necessary for depth-first search. */
345 struct depth_first_search_dsS {
346 /* stack for backtracking during the algorithm */
349 /* number of edges in the stack. That is, positions 0, ..., sp-1
353 /* record of basic blocks already seen by depth-first search */
354 sbitmap visited_blocks;
356 typedef struct depth_first_search_dsS *depth_first_search_ds;
358 /* Have print_rtl_and_abort give the same information that fancy_abort
360 #define print_rtl_and_abort() \
361 print_rtl_and_abort_fcn (__FILE__, __LINE__, __FUNCTION__)
363 /* Forward declarations */
364 static int count_basic_blocks PARAMS ((rtx));
365 static void find_basic_blocks_1 PARAMS ((rtx));
366 static rtx find_label_refs PARAMS ((rtx, rtx));
367 static void make_edges PARAMS ((rtx));
368 static void make_label_edge PARAMS ((sbitmap *, basic_block,
370 static void make_eh_edge PARAMS ((sbitmap *, basic_block, rtx));
372 static void commit_one_edge_insertion PARAMS ((edge));
374 static void delete_unreachable_blocks PARAMS ((void));
375 static int can_delete_note_p PARAMS ((rtx));
376 static void expunge_block PARAMS ((basic_block));
377 static int can_delete_label_p PARAMS ((rtx));
378 static int tail_recursion_label_p PARAMS ((rtx));
379 static int merge_blocks_move_predecessor_nojumps PARAMS ((basic_block,
381 static int merge_blocks_move_successor_nojumps PARAMS ((basic_block,
383 static int merge_blocks PARAMS ((edge,basic_block,basic_block));
384 static bool try_optimize_cfg PARAMS ((void));
385 static bool forwarder_block_p PARAMS ((basic_block));
386 static bool can_fallthru PARAMS ((basic_block, basic_block));
387 static bool try_redirect_by_replacing_jump PARAMS ((edge, basic_block));
388 static bool try_simplify_condjump PARAMS ((basic_block));
389 static bool try_forward_edges PARAMS ((basic_block));
390 static void tidy_fallthru_edges PARAMS ((void));
391 static int verify_wide_reg_1 PARAMS ((rtx *, void *));
392 static void verify_wide_reg PARAMS ((int, rtx, rtx));
393 static void verify_local_live_at_start PARAMS ((regset, basic_block));
394 static int noop_move_p PARAMS ((rtx));
395 static void delete_noop_moves PARAMS ((rtx));
396 static void notice_stack_pointer_modification_1 PARAMS ((rtx, rtx, void *));
397 static void notice_stack_pointer_modification PARAMS ((rtx));
398 static void mark_reg PARAMS ((rtx, void *));
399 static void mark_regs_live_at_end PARAMS ((regset));
400 static int set_phi_alternative_reg PARAMS ((rtx, int, int, void *));
401 static void calculate_global_regs_live PARAMS ((sbitmap, sbitmap, int));
402 static void propagate_block_delete_insn PARAMS ((basic_block, rtx));
403 static rtx propagate_block_delete_libcall PARAMS ((basic_block, rtx, rtx));
404 static int insn_dead_p PARAMS ((struct propagate_block_info *,
406 static int libcall_dead_p PARAMS ((struct propagate_block_info *,
408 static void mark_set_regs PARAMS ((struct propagate_block_info *,
410 static void mark_set_1 PARAMS ((struct propagate_block_info *,
411 enum rtx_code, rtx, rtx,
413 #ifdef HAVE_conditional_execution
414 static int mark_regno_cond_dead PARAMS ((struct propagate_block_info *,
416 static void free_reg_cond_life_info PARAMS ((splay_tree_value));
417 static int flush_reg_cond_reg_1 PARAMS ((splay_tree_node, void *));
418 static void flush_reg_cond_reg PARAMS ((struct propagate_block_info *,
420 static rtx elim_reg_cond PARAMS ((rtx, unsigned int));
421 static rtx ior_reg_cond PARAMS ((rtx, rtx, int));
422 static rtx not_reg_cond PARAMS ((rtx));
423 static rtx and_reg_cond PARAMS ((rtx, rtx, int));
426 static void attempt_auto_inc PARAMS ((struct propagate_block_info *,
427 rtx, rtx, rtx, rtx, rtx));
428 static void find_auto_inc PARAMS ((struct propagate_block_info *,
430 static int try_pre_increment_1 PARAMS ((struct propagate_block_info *,
432 static int try_pre_increment PARAMS ((rtx, rtx, HOST_WIDE_INT));
434 static void mark_used_reg PARAMS ((struct propagate_block_info *,
436 static void mark_used_regs PARAMS ((struct propagate_block_info *,
438 void dump_flow_info PARAMS ((FILE *));
439 void debug_flow_info PARAMS ((void));
440 static void print_rtl_and_abort_fcn PARAMS ((const char *, int,
444 static void invalidate_mems_from_autoinc PARAMS ((struct propagate_block_info *,
446 static void invalidate_mems_from_set PARAMS ((struct propagate_block_info *,
448 static void remove_fake_successors PARAMS ((basic_block));
449 static void flow_nodes_print PARAMS ((const char *, const sbitmap,
451 static void flow_edge_list_print PARAMS ((const char *, const edge *,
453 static void flow_loops_cfg_dump PARAMS ((const struct loops *,
455 static int flow_loop_nested_p PARAMS ((struct loop *,
457 static int flow_loop_entry_edges_find PARAMS ((basic_block, const sbitmap,
459 static int flow_loop_exit_edges_find PARAMS ((const sbitmap, edge **));
460 static int flow_loop_nodes_find PARAMS ((basic_block, basic_block, sbitmap));
461 static void flow_dfs_compute_reverse_init
462 PARAMS ((depth_first_search_ds));
463 static void flow_dfs_compute_reverse_add_bb
464 PARAMS ((depth_first_search_ds, basic_block));
465 static basic_block flow_dfs_compute_reverse_execute
466 PARAMS ((depth_first_search_ds));
467 static void flow_dfs_compute_reverse_finish
468 PARAMS ((depth_first_search_ds));
469 static void flow_loop_pre_header_scan PARAMS ((struct loop *));
470 static basic_block flow_loop_pre_header_find PARAMS ((basic_block,
472 static void flow_loop_tree_node_add PARAMS ((struct loop *, struct loop *));
473 static void flow_loops_tree_build PARAMS ((struct loops *));
474 static int flow_loop_level_compute PARAMS ((struct loop *, int));
475 static int flow_loops_level_compute PARAMS ((struct loops *));
476 static void allocate_bb_life_data PARAMS ((void));
477 static void find_sub_basic_blocks PARAMS ((basic_block));
478 static bool redirect_edge_and_branch PARAMS ((edge, basic_block));
479 static basic_block redirect_edge_and_branch_force PARAMS ((edge, basic_block));
480 static rtx block_label PARAMS ((basic_block));
482 /* Find basic blocks of the current function.
483 F is the first insn of the function and NREGS the number of register
487 find_basic_blocks (f, nregs, file)
489 int nregs ATTRIBUTE_UNUSED;
490 FILE *file ATTRIBUTE_UNUSED;
494 /* Flush out existing data. */
495 if (basic_block_info != NULL)
501 /* Clear bb->aux on all extant basic blocks. We'll use this as a
502 tag for reuse during create_basic_block, just in case some pass
503 copies around basic block notes improperly. */
504 for (i = 0; i < n_basic_blocks; ++i)
505 BASIC_BLOCK (i)->aux = NULL;
507 VARRAY_FREE (basic_block_info);
510 n_basic_blocks = count_basic_blocks (f);
512 /* Size the basic block table. The actual structures will be allocated
513 by find_basic_blocks_1, since we want to keep the structure pointers
514 stable across calls to find_basic_blocks. */
515 /* ??? This whole issue would be much simpler if we called find_basic_blocks
516 exactly once, and thereafter we don't have a single long chain of
517 instructions at all until close to the end of compilation when we
518 actually lay them out. */
520 VARRAY_BB_INIT (basic_block_info, n_basic_blocks, "basic_block_info");
522 find_basic_blocks_1 (f);
524 /* Record the block to which an insn belongs. */
525 /* ??? This should be done another way, by which (perhaps) a label is
526 tagged directly with the basic block that it starts. It is used for
527 more than that currently, but IMO that is the only valid use. */
529 max_uid = get_max_uid ();
531 /* Leave space for insns life_analysis makes in some cases for auto-inc.
532 These cases are rare, so we don't need too much space. */
533 max_uid += max_uid / 10;
536 compute_bb_for_insn (max_uid);
538 /* Discover the edges of our cfg. */
539 make_edges (label_value_list);
541 /* Do very simple cleanup now, for the benefit of code that runs between
542 here and cleanup_cfg, e.g. thread_prologue_and_epilogue_insns. */
543 tidy_fallthru_edges ();
545 mark_critical_edges ();
547 #ifdef ENABLE_CHECKING
553 check_function_return_warnings ()
555 if (warn_missing_noreturn
556 && !TREE_THIS_VOLATILE (cfun->decl)
557 && EXIT_BLOCK_PTR->pred == NULL
558 && (lang_missing_noreturn_ok_p
559 && !lang_missing_noreturn_ok_p (cfun->decl)))
560 warning ("function might be possible candidate for attribute `noreturn'");
562 /* If we have a path to EXIT, then we do return. */
563 if (TREE_THIS_VOLATILE (cfun->decl)
564 && EXIT_BLOCK_PTR->pred != NULL)
565 warning ("`noreturn' function does return");
567 /* If the clobber_return_insn appears in some basic block, then we
568 do reach the end without returning a value. */
569 else if (warn_return_type
570 && cfun->x_clobber_return_insn != NULL
571 && EXIT_BLOCK_PTR->pred != NULL)
573 int max_uid = get_max_uid ();
575 /* If clobber_return_insn was excised by jump1, then renumber_insns
576 can make max_uid smaller than the number still recorded in our rtx.
577 That's fine, since this is a quick way of verifying that the insn
578 is no longer in the chain. */
579 if (INSN_UID (cfun->x_clobber_return_insn) < max_uid)
581 /* Recompute insn->block mapping, since the initial mapping is
582 set before we delete unreachable blocks. */
583 compute_bb_for_insn (max_uid);
585 if (BLOCK_FOR_INSN (cfun->x_clobber_return_insn) != NULL)
586 warning ("control reaches end of non-void function");
591 /* Count the basic blocks of the function. */
594 count_basic_blocks (f)
598 register RTX_CODE prev_code;
599 register int count = 0;
600 int saw_abnormal_edge = 0;
602 prev_code = JUMP_INSN;
603 for (insn = f; insn; insn = NEXT_INSN (insn))
605 enum rtx_code code = GET_CODE (insn);
607 if (code == CODE_LABEL
608 || (GET_RTX_CLASS (code) == 'i'
609 && (prev_code == JUMP_INSN
610 || prev_code == BARRIER
611 || saw_abnormal_edge)))
613 saw_abnormal_edge = 0;
617 /* Record whether this insn created an edge. */
618 if (code == CALL_INSN)
622 /* If there is a nonlocal goto label and the specified
623 region number isn't -1, we have an edge. */
624 if (nonlocal_goto_handler_labels
625 && ((note = find_reg_note (insn, REG_EH_REGION, NULL_RTX)) == 0
626 || INTVAL (XEXP (note, 0)) >= 0))
627 saw_abnormal_edge = 1;
629 else if (can_throw_internal (insn))
630 saw_abnormal_edge = 1;
632 else if (flag_non_call_exceptions
634 && can_throw_internal (insn))
635 saw_abnormal_edge = 1;
641 /* The rest of the compiler works a bit smoother when we don't have to
642 check for the edge case of do-nothing functions with no basic blocks. */
645 emit_insn (gen_rtx_USE (VOIDmode, const0_rtx));
652 /* Scan a list of insns for labels referred to other than by jumps.
653 This is used to scan the alternatives of a call placeholder. */
655 find_label_refs (f, lvl)
661 for (insn = f; insn; insn = NEXT_INSN (insn))
662 if (INSN_P (insn) && GET_CODE (insn) != JUMP_INSN)
666 /* Make a list of all labels referred to other than by jumps
667 (which just don't have the REG_LABEL notes).
669 Make a special exception for labels followed by an ADDR*VEC,
670 as this would be a part of the tablejump setup code.
672 Make a special exception to registers loaded with label
673 values just before jump insns that use them. */
675 for (note = REG_NOTES (insn); note; note = XEXP (note, 1))
676 if (REG_NOTE_KIND (note) == REG_LABEL)
678 rtx lab = XEXP (note, 0), next;
680 if ((next = next_nonnote_insn (lab)) != NULL
681 && GET_CODE (next) == JUMP_INSN
682 && (GET_CODE (PATTERN (next)) == ADDR_VEC
683 || GET_CODE (PATTERN (next)) == ADDR_DIFF_VEC))
685 else if (GET_CODE (lab) == NOTE)
687 else if (GET_CODE (NEXT_INSN (insn)) == JUMP_INSN
688 && find_reg_note (NEXT_INSN (insn), REG_LABEL, lab))
691 lvl = alloc_EXPR_LIST (0, XEXP (note, 0), lvl);
698 /* Assume that someone emitted code with control flow instructions to the
699 basic block. Update the data structure. */
701 find_sub_basic_blocks (bb)
704 rtx first_insn = bb->head, insn;
706 edge succ_list = bb->succ;
707 rtx jump_insn = NULL_RTX;
711 basic_block first_bb = bb, last_bb;
714 if (GET_CODE (first_insn) == LABEL_REF)
715 first_insn = NEXT_INSN (first_insn);
716 first_insn = NEXT_INSN (first_insn);
720 /* Scan insn chain and try to find new basic block boundaries. */
723 enum rtx_code code = GET_CODE (insn);
727 /* We need some special care for those expressions. */
728 if (GET_CODE (PATTERN (insn)) == ADDR_VEC
729 || GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC)
738 /* On code label, split current basic block. */
740 falltru = split_block (bb, PREV_INSN (insn));
745 remove_edge (falltru);
749 if (LABEL_ALTERNATE_NAME (insn))
750 make_edge (NULL, ENTRY_BLOCK_PTR, bb, 0);
753 /* In case we've previously split insn on the JUMP_INSN, move the
754 block header to proper place. */
757 falltru = split_block (bb, PREV_INSN (insn));
767 insn = NEXT_INSN (insn);
769 /* Last basic block must end in the original BB end. */
773 /* Wire in the original edges for last basic block. */
776 bb->succ = succ_list;
778 succ_list->src = bb, succ_list = succ_list->succ_next;
781 bb->succ = succ_list;
783 /* Now re-scan and wire in all edges. This expect simple (conditional)
784 jumps at the end of each new basic blocks. */
786 for (i = first_bb->index; i < last_bb->index; i++)
788 bb = BASIC_BLOCK (i);
789 if (GET_CODE (bb->end) == JUMP_INSN)
791 mark_jump_label (PATTERN (bb->end), bb->end, 0, 0);
792 make_label_edge (NULL, bb, JUMP_LABEL (bb->end), 0);
794 insn = NEXT_INSN (insn);
798 /* Find all basic blocks of the function whose first insn is F.
800 Collect and return a list of labels whose addresses are taken. This
801 will be used in make_edges for use with computed gotos. */
804 find_basic_blocks_1 (f)
807 register rtx insn, next;
809 rtx bb_note = NULL_RTX;
815 /* We process the instructions in a slightly different way than we did
816 previously. This is so that we see a NOTE_BASIC_BLOCK after we have
817 closed out the previous block, so that it gets attached at the proper
818 place. Since this form should be equivalent to the previous,
819 count_basic_blocks continues to use the old form as a check. */
821 for (insn = f; insn; insn = next)
823 enum rtx_code code = GET_CODE (insn);
825 next = NEXT_INSN (insn);
831 int kind = NOTE_LINE_NUMBER (insn);
833 /* Look for basic block notes with which to keep the
834 basic_block_info pointers stable. Unthread the note now;
835 we'll put it back at the right place in create_basic_block.
836 Or not at all if we've already found a note in this block. */
837 if (kind == NOTE_INSN_BASIC_BLOCK)
839 if (bb_note == NULL_RTX)
842 next = flow_delete_insn (insn);
848 /* A basic block starts at a label. If we've closed one off due
849 to a barrier or some such, no need to do it again. */
850 if (head != NULL_RTX)
852 /* While we now have edge lists with which other portions of
853 the compiler might determine a call ending a basic block
854 does not imply an abnormal edge, it will be a bit before
855 everything can be updated. So continue to emit a noop at
856 the end of such a block. */
857 if (GET_CODE (end) == CALL_INSN && ! SIBLING_CALL_P (end))
859 rtx nop = gen_rtx_USE (VOIDmode, const0_rtx);
860 end = emit_insn_after (nop, end);
863 create_basic_block (i++, head, end, bb_note);
871 /* A basic block ends at a jump. */
872 if (head == NULL_RTX)
876 /* ??? Make a special check for table jumps. The way this
877 happens is truly and amazingly gross. We are about to
878 create a basic block that contains just a code label and
879 an addr*vec jump insn. Worse, an addr_diff_vec creates
880 its own natural loop.
882 Prevent this bit of brain damage, pasting things together
883 correctly in make_edges.
885 The correct solution involves emitting the table directly
886 on the tablejump instruction as a note, or JUMP_LABEL. */
888 if (GET_CODE (PATTERN (insn)) == ADDR_VEC
889 || GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC)
897 goto new_bb_inclusive;
900 /* A basic block ends at a barrier. It may be that an unconditional
901 jump already closed the basic block -- no need to do it again. */
902 if (head == NULL_RTX)
905 /* While we now have edge lists with which other portions of the
906 compiler might determine a call ending a basic block does not
907 imply an abnormal edge, it will be a bit before everything can
908 be updated. So continue to emit a noop at the end of such a
910 if (GET_CODE (end) == CALL_INSN && ! SIBLING_CALL_P (end))
912 rtx nop = gen_rtx_USE (VOIDmode, const0_rtx);
913 end = emit_insn_after (nop, end);
915 goto new_bb_exclusive;
919 /* Record whether this call created an edge. */
920 rtx note = find_reg_note (insn, REG_EH_REGION, NULL_RTX);
921 int region = (note ? INTVAL (XEXP (note, 0)) : 0);
923 if (GET_CODE (PATTERN (insn)) == CALL_PLACEHOLDER)
925 /* Scan each of the alternatives for label refs. */
926 lvl = find_label_refs (XEXP (PATTERN (insn), 0), lvl);
927 lvl = find_label_refs (XEXP (PATTERN (insn), 1), lvl);
928 lvl = find_label_refs (XEXP (PATTERN (insn), 2), lvl);
929 /* Record its tail recursion label, if any. */
930 if (XEXP (PATTERN (insn), 3) != NULL_RTX)
931 trll = alloc_EXPR_LIST (0, XEXP (PATTERN (insn), 3), trll);
934 /* A basic block ends at a call that can either throw or
935 do a non-local goto. */
936 if ((nonlocal_goto_handler_labels && region >= 0)
937 || can_throw_internal (insn))
940 if (head == NULL_RTX)
945 create_basic_block (i++, head, end, bb_note);
946 head = end = NULL_RTX;
954 /* Non-call exceptions generate new blocks just like calls. */
955 if (flag_non_call_exceptions && can_throw_internal (insn))
956 goto new_bb_inclusive;
958 if (head == NULL_RTX)
967 if (GET_CODE (insn) == INSN || GET_CODE (insn) == CALL_INSN)
971 /* Make a list of all labels referred to other than by jumps.
973 Make a special exception for labels followed by an ADDR*VEC,
974 as this would be a part of the tablejump setup code.
976 Make a special exception to registers loaded with label
977 values just before jump insns that use them. */
979 for (note = REG_NOTES (insn); note; note = XEXP (note, 1))
980 if (REG_NOTE_KIND (note) == REG_LABEL)
982 rtx lab = XEXP (note, 0), next;
984 if ((next = next_nonnote_insn (lab)) != NULL
985 && GET_CODE (next) == JUMP_INSN
986 && (GET_CODE (PATTERN (next)) == ADDR_VEC
987 || GET_CODE (PATTERN (next)) == ADDR_DIFF_VEC))
989 else if (GET_CODE (lab) == NOTE)
991 else if (GET_CODE (NEXT_INSN (insn)) == JUMP_INSN
992 && find_reg_note (NEXT_INSN (insn), REG_LABEL, lab))
995 lvl = alloc_EXPR_LIST (0, XEXP (note, 0), lvl);
1000 if (head != NULL_RTX)
1001 create_basic_block (i++, head, end, bb_note);
1003 flow_delete_insn (bb_note);
1005 if (i != n_basic_blocks)
1008 label_value_list = lvl;
1009 tail_recursion_label_list = trll;
1012 /* Tidy the CFG by deleting unreachable code and whatnot. */
1017 delete_unreachable_blocks ();
1018 if (try_optimize_cfg ())
1019 delete_unreachable_blocks ();
1020 mark_critical_edges ();
1022 /* Kill the data we won't maintain. */
1023 free_EXPR_LIST_list (&label_value_list);
1024 free_EXPR_LIST_list (&tail_recursion_label_list);
1027 /* Create a new basic block consisting of the instructions between
1028 HEAD and END inclusive. Reuses the note and basic block struct
1029 in BB_NOTE, if any. */
1032 create_basic_block (index, head, end, bb_note)
1034 rtx head, end, bb_note;
1039 && ! RTX_INTEGRATED_P (bb_note)
1040 && (bb = NOTE_BASIC_BLOCK (bb_note)) != NULL
1043 /* If we found an existing note, thread it back onto the chain. */
1047 if (GET_CODE (head) == CODE_LABEL)
1051 after = PREV_INSN (head);
1055 if (after != bb_note && NEXT_INSN (after) != bb_note)
1056 reorder_insns (bb_note, bb_note, after);
1060 /* Otherwise we must create a note and a basic block structure.
1061 Since we allow basic block structs in rtl, give the struct
1062 the same lifetime by allocating it off the function obstack
1063 rather than using malloc. */
1065 bb = (basic_block) obstack_alloc (&flow_obstack, sizeof (*bb));
1066 memset (bb, 0, sizeof (*bb));
1068 if (GET_CODE (head) == CODE_LABEL)
1069 bb_note = emit_note_after (NOTE_INSN_BASIC_BLOCK, head);
1072 bb_note = emit_note_before (NOTE_INSN_BASIC_BLOCK, head);
1075 NOTE_BASIC_BLOCK (bb_note) = bb;
1078 /* Always include the bb note in the block. */
1079 if (NEXT_INSN (end) == bb_note)
1085 BASIC_BLOCK (index) = bb;
1087 /* Tag the block so that we know it has been used when considering
1088 other basic block notes. */
1092 /* Return the INSN immediately following the NOTE_INSN_BASIC_BLOCK
1093 note associated with the BLOCK. */
1096 first_insn_after_basic_block_note (block)
1101 /* Get the first instruction in the block. */
1104 if (insn == NULL_RTX)
1106 if (GET_CODE (insn) == CODE_LABEL)
1107 insn = NEXT_INSN (insn);
1108 if (!NOTE_INSN_BASIC_BLOCK_P (insn))
1111 return NEXT_INSN (insn);
1114 /* Records the basic block struct in BB_FOR_INSN, for every instruction
1115 indexed by INSN_UID. MAX is the size of the array. */
1118 compute_bb_for_insn (max)
1123 if (basic_block_for_insn)
1124 VARRAY_FREE (basic_block_for_insn);
1125 VARRAY_BB_INIT (basic_block_for_insn, max, "basic_block_for_insn");
1127 for (i = 0; i < n_basic_blocks; ++i)
1129 basic_block bb = BASIC_BLOCK (i);
1136 int uid = INSN_UID (insn);
1138 VARRAY_BB (basic_block_for_insn, uid) = bb;
1141 insn = NEXT_INSN (insn);
1146 /* Free the memory associated with the edge structures. */
1154 for (i = 0; i < n_basic_blocks; ++i)
1156 basic_block bb = BASIC_BLOCK (i);
1158 for (e = bb->succ; e; e = n)
1168 for (e = ENTRY_BLOCK_PTR->succ; e; e = n)
1174 ENTRY_BLOCK_PTR->succ = 0;
1175 EXIT_BLOCK_PTR->pred = 0;
1180 /* Identify the edges between basic blocks.
1182 NONLOCAL_LABEL_LIST is a list of non-local labels in the function. Blocks
1183 that are otherwise unreachable may be reachable with a non-local goto.
1185 BB_EH_END is an array indexed by basic block number in which we record
1186 the list of exception regions active at the end of the basic block. */
1189 make_edges (label_value_list)
1190 rtx label_value_list;
1193 sbitmap *edge_cache = NULL;
1195 /* Assume no computed jump; revise as we create edges. */
1196 current_function_has_computed_jump = 0;
1198 /* Heavy use of computed goto in machine-generated code can lead to
1199 nearly fully-connected CFGs. In that case we spend a significant
1200 amount of time searching the edge lists for duplicates. */
1201 if (forced_labels || label_value_list)
1203 edge_cache = sbitmap_vector_alloc (n_basic_blocks, n_basic_blocks);
1204 sbitmap_vector_zero (edge_cache, n_basic_blocks);
1207 /* By nature of the way these get numbered, block 0 is always the entry. */
1208 make_edge (edge_cache, ENTRY_BLOCK_PTR, BASIC_BLOCK (0), EDGE_FALLTHRU);
1210 for (i = 0; i < n_basic_blocks; ++i)
1212 basic_block bb = BASIC_BLOCK (i);
1215 int force_fallthru = 0;
1217 if (GET_CODE (bb->head) == CODE_LABEL
1218 && LABEL_ALTERNATE_NAME (bb->head))
1219 make_edge (NULL, ENTRY_BLOCK_PTR, bb, 0);
1221 /* Examine the last instruction of the block, and discover the
1222 ways we can leave the block. */
1225 code = GET_CODE (insn);
1228 if (code == JUMP_INSN)
1232 /* Recognize exception handling placeholders. */
1233 if (GET_CODE (PATTERN (insn)) == RESX)
1234 make_eh_edge (edge_cache, bb, insn);
1236 /* Recognize a non-local goto as a branch outside the
1237 current function. */
1238 else if (find_reg_note (insn, REG_NON_LOCAL_GOTO, NULL_RTX))
1241 /* ??? Recognize a tablejump and do the right thing. */
1242 else if ((tmp = JUMP_LABEL (insn)) != NULL_RTX
1243 && (tmp = NEXT_INSN (tmp)) != NULL_RTX
1244 && GET_CODE (tmp) == JUMP_INSN
1245 && (GET_CODE (PATTERN (tmp)) == ADDR_VEC
1246 || GET_CODE (PATTERN (tmp)) == ADDR_DIFF_VEC))
1251 if (GET_CODE (PATTERN (tmp)) == ADDR_VEC)
1252 vec = XVEC (PATTERN (tmp), 0);
1254 vec = XVEC (PATTERN (tmp), 1);
1256 for (j = GET_NUM_ELEM (vec) - 1; j >= 0; --j)
1257 make_label_edge (edge_cache, bb,
1258 XEXP (RTVEC_ELT (vec, j), 0), 0);
1260 /* Some targets (eg, ARM) emit a conditional jump that also
1261 contains the out-of-range target. Scan for these and
1262 add an edge if necessary. */
1263 if ((tmp = single_set (insn)) != NULL
1264 && SET_DEST (tmp) == pc_rtx
1265 && GET_CODE (SET_SRC (tmp)) == IF_THEN_ELSE
1266 && GET_CODE (XEXP (SET_SRC (tmp), 2)) == LABEL_REF)
1267 make_label_edge (edge_cache, bb,
1268 XEXP (XEXP (SET_SRC (tmp), 2), 0), 0);
1270 #ifdef CASE_DROPS_THROUGH
1271 /* Silly VAXen. The ADDR_VEC is going to be in the way of
1272 us naturally detecting fallthru into the next block. */
1277 /* If this is a computed jump, then mark it as reaching
1278 everything on the label_value_list and forced_labels list. */
1279 else if (computed_jump_p (insn))
1281 current_function_has_computed_jump = 1;
1283 for (x = label_value_list; x; x = XEXP (x, 1))
1284 make_label_edge (edge_cache, bb, XEXP (x, 0), EDGE_ABNORMAL);
1286 for (x = forced_labels; x; x = XEXP (x, 1))
1287 make_label_edge (edge_cache, bb, XEXP (x, 0), EDGE_ABNORMAL);
1290 /* Returns create an exit out. */
1291 else if (returnjump_p (insn))
1292 make_edge (edge_cache, bb, EXIT_BLOCK_PTR, 0);
1294 /* Otherwise, we have a plain conditional or unconditional jump. */
1297 if (! JUMP_LABEL (insn))
1299 make_label_edge (edge_cache, bb, JUMP_LABEL (insn), 0);
1303 /* If this is a sibling call insn, then this is in effect a
1304 combined call and return, and so we need an edge to the
1305 exit block. No need to worry about EH edges, since we
1306 wouldn't have created the sibling call in the first place. */
1308 if (code == CALL_INSN && SIBLING_CALL_P (insn))
1309 make_edge (edge_cache, bb, EXIT_BLOCK_PTR,
1310 EDGE_ABNORMAL | EDGE_ABNORMAL_CALL);
1312 /* If this is a CALL_INSN, then mark it as reaching the active EH
1313 handler for this CALL_INSN. If we're handling non-call
1314 exceptions then any insn can reach any of the active handlers.
1316 Also mark the CALL_INSN as reaching any nonlocal goto handler. */
1318 else if (code == CALL_INSN || flag_non_call_exceptions)
1320 /* Add any appropriate EH edges. */
1321 make_eh_edge (edge_cache, bb, insn);
1323 if (code == CALL_INSN && nonlocal_goto_handler_labels)
1325 /* ??? This could be made smarter: in some cases it's possible
1326 to tell that certain calls will not do a nonlocal goto.
1328 For example, if the nested functions that do the nonlocal
1329 gotos do not have their addresses taken, then only calls to
1330 those functions or to other nested functions that use them
1331 could possibly do nonlocal gotos. */
1332 /* We do know that a REG_EH_REGION note with a value less
1333 than 0 is guaranteed not to perform a non-local goto. */
1334 rtx note = find_reg_note (insn, REG_EH_REGION, NULL_RTX);
1335 if (!note || INTVAL (XEXP (note, 0)) >= 0)
1336 for (x = nonlocal_goto_handler_labels; x; x = XEXP (x, 1))
1337 make_label_edge (edge_cache, bb, XEXP (x, 0),
1338 EDGE_ABNORMAL | EDGE_ABNORMAL_CALL);
1342 /* Find out if we can drop through to the next block. */
1343 insn = next_nonnote_insn (insn);
1344 if (!insn || (i + 1 == n_basic_blocks && force_fallthru))
1345 make_edge (edge_cache, bb, EXIT_BLOCK_PTR, EDGE_FALLTHRU);
1346 else if (i + 1 < n_basic_blocks)
1348 rtx tmp = BLOCK_HEAD (i + 1);
1349 if (GET_CODE (tmp) == NOTE)
1350 tmp = next_nonnote_insn (tmp);
1351 if (force_fallthru || insn == tmp)
1352 make_edge (edge_cache, bb, BASIC_BLOCK (i + 1), EDGE_FALLTHRU);
1357 sbitmap_vector_free (edge_cache);
1360 /* Create an edge between two basic blocks. FLAGS are auxiliary information
1361 about the edge that is accumulated between calls. */
1364 make_edge (edge_cache, src, dst, flags)
1365 sbitmap *edge_cache;
1366 basic_block src, dst;
1372 /* Don't bother with edge cache for ENTRY or EXIT; there aren't that
1373 many edges to them, and we didn't allocate memory for it. */
1374 use_edge_cache = (edge_cache
1375 && src != ENTRY_BLOCK_PTR
1376 && dst != EXIT_BLOCK_PTR);
1378 /* Make sure we don't add duplicate edges. */
1379 switch (use_edge_cache)
1382 /* Quick test for non-existance of the edge. */
1383 if (! TEST_BIT (edge_cache[src->index], dst->index))
1386 /* The edge exists; early exit if no work to do. */
1392 for (e = src->succ; e; e = e->succ_next)
1401 e = (edge) xcalloc (1, sizeof (*e));
1404 e->succ_next = src->succ;
1405 e->pred_next = dst->pred;
1414 SET_BIT (edge_cache[src->index], dst->index);
1417 /* Create an edge from a basic block to a label. */
1420 make_label_edge (edge_cache, src, label, flags)
1421 sbitmap *edge_cache;
1426 if (GET_CODE (label) != CODE_LABEL)
1429 /* If the label was never emitted, this insn is junk, but avoid a
1430 crash trying to refer to BLOCK_FOR_INSN (label). This can happen
1431 as a result of a syntax error and a diagnostic has already been
1434 if (INSN_UID (label) == 0)
1437 make_edge (edge_cache, src, BLOCK_FOR_INSN (label), flags);
1440 /* Create the edges generated by INSN in REGION. */
1443 make_eh_edge (edge_cache, src, insn)
1444 sbitmap *edge_cache;
1448 int is_call = (GET_CODE (insn) == CALL_INSN ? EDGE_ABNORMAL_CALL : 0);
1451 handlers = reachable_handlers (insn);
1453 for (i = handlers; i; i = XEXP (i, 1))
1454 make_label_edge (edge_cache, src, XEXP (i, 0),
1455 EDGE_ABNORMAL | EDGE_EH | is_call);
1457 free_INSN_LIST_list (&handlers);
1460 /* Identify critical edges and set the bits appropriately. */
1463 mark_critical_edges ()
1465 int i, n = n_basic_blocks;
1468 /* We begin with the entry block. This is not terribly important now,
1469 but could be if a front end (Fortran) implemented alternate entry
1471 bb = ENTRY_BLOCK_PTR;
1478 /* (1) Critical edges must have a source with multiple successors. */
1479 if (bb->succ && bb->succ->succ_next)
1481 for (e = bb->succ; e; e = e->succ_next)
1483 /* (2) Critical edges must have a destination with multiple
1484 predecessors. Note that we know there is at least one
1485 predecessor -- the edge we followed to get here. */
1486 if (e->dest->pred->pred_next)
1487 e->flags |= EDGE_CRITICAL;
1489 e->flags &= ~EDGE_CRITICAL;
1494 for (e = bb->succ; e; e = e->succ_next)
1495 e->flags &= ~EDGE_CRITICAL;
1500 bb = BASIC_BLOCK (i);
1504 /* Split a block BB after insn INSN creating a new fallthru edge.
1505 Return the new edge. Note that to keep other parts of the compiler happy,
1506 this function renumbers all the basic blocks so that the new
1507 one has a number one greater than the block split. */
1510 split_block (bb, insn)
1520 /* There is no point splitting the block after its end. */
1521 if (bb->end == insn)
1524 /* Create the new structures. */
1525 new_bb = (basic_block) obstack_alloc (&flow_obstack, sizeof (*new_bb));
1526 new_edge = (edge) xcalloc (1, sizeof (*new_edge));
1529 memset (new_bb, 0, sizeof (*new_bb));
1531 new_bb->head = NEXT_INSN (insn);
1532 new_bb->end = bb->end;
1535 new_bb->succ = bb->succ;
1536 bb->succ = new_edge;
1537 new_bb->pred = new_edge;
1538 new_bb->count = bb->count;
1539 new_bb->frequency = bb->frequency;
1540 new_bb->loop_depth = bb->loop_depth;
1543 new_edge->dest = new_bb;
1544 new_edge->flags = EDGE_FALLTHRU;
1545 new_edge->probability = REG_BR_PROB_BASE;
1546 new_edge->count = bb->count;
1548 /* Redirect the src of the successor edges of bb to point to new_bb. */
1549 for (e = new_bb->succ; e; e = e->succ_next)
1552 /* Place the new block just after the block being split. */
1553 VARRAY_GROW (basic_block_info, ++n_basic_blocks);
1555 /* Some parts of the compiler expect blocks to be number in
1556 sequential order so insert the new block immediately after the
1557 block being split.. */
1559 for (i = n_basic_blocks - 1; i > j + 1; --i)
1561 basic_block tmp = BASIC_BLOCK (i - 1);
1562 BASIC_BLOCK (i) = tmp;
1566 BASIC_BLOCK (i) = new_bb;
1569 if (GET_CODE (new_bb->head) == CODE_LABEL)
1571 /* Create the basic block note. */
1572 bb_note = emit_note_after (NOTE_INSN_BASIC_BLOCK,
1574 NOTE_BASIC_BLOCK (bb_note) = new_bb;
1578 /* Create the basic block note. */
1579 bb_note = emit_note_before (NOTE_INSN_BASIC_BLOCK,
1581 NOTE_BASIC_BLOCK (bb_note) = new_bb;
1582 new_bb->head = bb_note;
1585 update_bb_for_insn (new_bb);
1587 if (bb->global_live_at_start)
1589 new_bb->global_live_at_start = OBSTACK_ALLOC_REG_SET (&flow_obstack);
1590 new_bb->global_live_at_end = OBSTACK_ALLOC_REG_SET (&flow_obstack);
1591 COPY_REG_SET (new_bb->global_live_at_end, bb->global_live_at_end);
1593 /* We now have to calculate which registers are live at the end
1594 of the split basic block and at the start of the new basic
1595 block. Start with those registers that are known to be live
1596 at the end of the original basic block and get
1597 propagate_block to determine which registers are live. */
1598 COPY_REG_SET (new_bb->global_live_at_start, bb->global_live_at_end);
1599 propagate_block (new_bb, new_bb->global_live_at_start, NULL, NULL, 0);
1600 COPY_REG_SET (bb->global_live_at_end,
1601 new_bb->global_live_at_start);
1607 /* Return label in the head of basic block. Create one if it doesn't exist. */
1612 if (GET_CODE (block->head) != CODE_LABEL)
1613 block->head = emit_label_before (gen_label_rtx (), block->head);
1617 /* Return true if the block has no effect and only forwards control flow to
1618 its single destination. */
1620 forwarder_block_p (bb)
1623 rtx insn = bb->head;
1624 if (bb == EXIT_BLOCK_PTR || bb == ENTRY_BLOCK_PTR
1625 || !bb->succ || bb->succ->succ_next)
1628 while (insn != bb->end)
1630 if (active_insn_p (insn))
1632 insn = NEXT_INSN (insn);
1634 return (!active_insn_p (insn)
1635 || (GET_CODE (insn) == JUMP_INSN && onlyjump_p (insn)));
1638 /* Return nonzero if we can reach target from src by falling trought. */
1640 can_fallthru (src, target)
1641 basic_block src, target;
1643 rtx insn = src->end;
1644 rtx insn2 = target->head;
1646 if (src->index + 1 == target->index && !active_insn_p (insn2))
1647 insn2 = next_active_insn (insn2);
1648 /* ??? Later we may add code to move jump tables offline. */
1649 return next_active_insn (insn) == insn2;
1652 /* Attempt to perform edge redirection by replacing possibly complex jump
1653 instruction by unconditional jump or removing jump completely.
1654 This can apply only if all edges now point to the same block.
1656 The parameters and return values are equivalent to redirect_edge_and_branch.
1659 try_redirect_by_replacing_jump (e, target)
1663 basic_block src = e->src;
1664 rtx insn = src->end;
1669 /* Verify that all targets will be TARGET. */
1670 for (tmp = src->succ; tmp; tmp = tmp->succ_next)
1671 if (tmp->dest != target && tmp != e)
1673 if (tmp || !onlyjump_p (insn))
1676 /* Avoid removing branch with side effects. */
1677 set = single_set (insn);
1678 if (!set || side_effects_p (set))
1681 /* See if we can create the fallthru edge. */
1682 if (can_fallthru (src, target))
1684 src->end = PREV_INSN (insn);
1686 fprintf (rtl_dump_file, "Removing jump %i.\n", INSN_UID (insn));
1687 flow_delete_insn (insn);
1690 /* Selectivly unlink whole insn chain. */
1691 if (src->end != PREV_INSN (target->head))
1692 flow_delete_insn_chain (NEXT_INSN (src->end),
1693 PREV_INSN (target->head));
1695 /* If this already is simplejump, redirect it. */
1696 else if (simplejump_p (insn))
1698 if (e->dest == target)
1701 fprintf (rtl_dump_file, "Redirecting jump %i from %i to %i.\n",
1702 INSN_UID (insn), e->dest->index, target->index);
1703 redirect_jump (insn, block_label (target), 0);
1705 /* Or replace possibly complicated jump insn by simple jump insn. */
1708 rtx target_label = block_label (target);
1711 src->end = PREV_INSN (insn);
1712 src->end = emit_jump_insn_after (gen_jump (target_label), src->end);
1713 JUMP_LABEL (src->end) = target_label;
1714 LABEL_NUSES (target_label)++;
1715 if (basic_block_for_insn)
1716 set_block_for_new_insns (src->end, src);
1718 fprintf (rtl_dump_file, "Replacing insn %i by jump %i\n",
1719 INSN_UID (insn), INSN_UID (src->end));
1720 flow_delete_insn (insn);
1721 barrier = next_nonnote_insn (src->end);
1722 if (!barrier || GET_CODE (barrier) != BARRIER)
1723 emit_barrier_after (src->end);
1726 /* Keep only one edge out and set proper flags. */
1727 while (src->succ->succ_next)
1728 remove_edge (src->succ);
1731 e->flags = EDGE_FALLTHRU;
1734 e->probability = REG_BR_PROB_BASE;
1735 e->count = src->count;
1737 /* In case we've zapped an conditional jump, we need to kill the cc0
1738 setter too if available. */
1741 if (GET_CODE (insn) == JUMP_INSN)
1742 insn = prev_nonnote_insn (insn);
1743 if (sets_cc0_p (insn))
1745 if (insn == src->end)
1746 src->end = PREV_INSN (insn);
1747 flow_delete_insn (insn);
1751 /* We don't want a block to end on a line-number note since that has
1752 the potential of changing the code between -g and not -g. */
1753 while (GET_CODE (e->src->end) == NOTE
1754 && NOTE_LINE_NUMBER (e->src->end) >= 0)
1756 rtx prev = PREV_INSN (e->src->end);
1757 flow_delete_insn (e->src->end);
1761 if (e->dest != target)
1762 redirect_edge_succ (e, target);
1766 /* Attempt to change code to redirect edge E to TARGET.
1767 Don't do that on expense of adding new instructions or reordering
1770 Function can be also called with edge destionation equivalent to the
1771 TARGET. Then it should try the simplifications and do nothing if
1774 Return true if transformation suceeded. We still return flase in case
1775 E already destinated TARGET and we didn't managed to simplify instruction
1778 redirect_edge_and_branch (e, target)
1783 rtx old_label = e->dest->head;
1784 basic_block src = e->src;
1785 rtx insn = src->end;
1787 if (try_redirect_by_replacing_jump (e, target))
1789 /* Do this fast path late, as we want above code to simplify for cases
1790 where called on single edge leaving basic block containing nontrivial
1792 else if (e->dest == target)
1795 /* We can only redirect non-fallthru edges of jump insn. */
1796 if (e->flags & EDGE_FALLTHRU)
1798 if (GET_CODE (insn) != JUMP_INSN)
1801 /* Recognize a tablejump and adjust all matching cases. */
1802 if ((tmp = JUMP_LABEL (insn)) != NULL_RTX
1803 && (tmp = NEXT_INSN (tmp)) != NULL_RTX
1804 && GET_CODE (tmp) == JUMP_INSN
1805 && (GET_CODE (PATTERN (tmp)) == ADDR_VEC
1806 || GET_CODE (PATTERN (tmp)) == ADDR_DIFF_VEC))
1810 rtx new_label = block_label (target);
1812 if (GET_CODE (PATTERN (tmp)) == ADDR_VEC)
1813 vec = XVEC (PATTERN (tmp), 0);
1815 vec = XVEC (PATTERN (tmp), 1);
1817 for (j = GET_NUM_ELEM (vec) - 1; j >= 0; --j)
1818 if (XEXP (RTVEC_ELT (vec, j), 0) == old_label)
1820 RTVEC_ELT (vec, j) = gen_rtx_LABEL_REF (Pmode, new_label);
1821 --LABEL_NUSES (old_label);
1822 ++LABEL_NUSES (new_label);
1825 /* Handle casesi dispatch insns */
1826 if ((tmp = single_set (insn)) != NULL
1827 && SET_DEST (tmp) == pc_rtx
1828 && GET_CODE (SET_SRC (tmp)) == IF_THEN_ELSE
1829 && GET_CODE (XEXP (SET_SRC (tmp), 2)) == LABEL_REF
1830 && XEXP (XEXP (SET_SRC (tmp), 2), 0) == old_label)
1832 XEXP (SET_SRC (tmp), 2) = gen_rtx_LABEL_REF (VOIDmode,
1834 --LABEL_NUSES (old_label);
1835 ++LABEL_NUSES (new_label);
1840 /* ?? We may play the games with moving the named labels from
1841 one basic block to the other in case only one computed_jump is
1843 if (computed_jump_p (insn))
1846 /* A return instruction can't be redirected. */
1847 if (returnjump_p (insn))
1850 /* If the insn doesn't go where we think, we're confused. */
1851 if (JUMP_LABEL (insn) != old_label)
1853 redirect_jump (insn, block_label (target), 0);
1857 fprintf (rtl_dump_file, "Edge %i->%i redirected to %i\n",
1858 e->src->index, e->dest->index, target->index);
1859 if (e->dest != target)
1862 /* Check whether the edge is already present. */
1863 for (s = src->succ; s; s=s->succ_next)
1864 if (s->dest == target)
1868 s->flags |= e->flags;
1869 s->probability += e->probability;
1870 s->count += e->count;
1874 redirect_edge_succ (e, target);
1879 /* Redirect edge even at the expense of creating new jump insn or
1880 basic block. Return new basic block if created, NULL otherwise.
1881 Abort if converison is impossible. */
1883 redirect_edge_and_branch_force (e, target)
1893 if (redirect_edge_and_branch (e, target))
1895 if (e->dest == target)
1897 if (e->flags & EDGE_ABNORMAL)
1899 if (!(e->flags & EDGE_FALLTHRU))
1902 e->flags &= ~EDGE_FALLTHRU;
1903 label = block_label (target);
1904 /* Case of the fallthru block. */
1905 if (!e->src->succ->succ_next)
1907 e->src->end = emit_jump_insn_after (gen_jump (label), e->src->end);
1908 JUMP_LABEL (e->src->end) = label;
1909 LABEL_NUSES (label)++;
1910 if (basic_block_for_insn)
1911 set_block_for_insn (e->src->end, e->src);
1912 emit_barrier_after (e->src->end);
1914 fprintf (rtl_dump_file,
1915 "Emitting jump insn %i to redirect edge %i->%i to %i\n",
1916 INSN_UID (e->src->end), e->src->index, e->dest->index,
1918 redirect_edge_succ (e, target);
1921 /* Redirecting fallthru edge of the conditional needs extra work. */
1924 fprintf (rtl_dump_file,
1925 "Emitting jump insn %i in new BB to redirect edge %i->%i to %i\n",
1926 INSN_UID (e->src->end), e->src->index, e->dest->index,
1929 /* Create the new structures. */
1930 new_bb = (basic_block) obstack_alloc (&flow_obstack, sizeof (*new_bb));
1931 new_edge = (edge) xcalloc (1, sizeof (*new_edge));
1934 memset (new_bb, 0, sizeof (*new_bb));
1936 new_bb->end = new_bb->head = e->src->end;
1937 new_bb->succ = NULL;
1938 new_bb->pred = new_edge;
1939 new_bb->count = e->count;
1940 new_bb->frequency = e->probability * e->src->frequency / REG_BR_PROB_BASE;
1941 new_bb->loop_depth = e->dest->loop_depth;
1943 new_edge->flags = EDGE_FALLTHRU;
1944 new_edge->probability = e->probability;
1945 new_edge->count = e->count;
1948 new_edge->src = e->src;
1949 new_edge->dest = new_bb;
1950 new_edge->succ_next = e->src->succ;
1951 e->src->succ = new_edge;
1952 new_edge->pred_next = NULL;
1954 /* Redirect old edge. */
1955 redirect_edge_succ (e, target);
1956 redirect_edge_pred (e, new_bb);
1957 e->probability = REG_BR_PROB_BASE;
1959 /* Place the new block just after the block being split. */
1960 VARRAY_GROW (basic_block_info, ++n_basic_blocks);
1962 /* Some parts of the compiler expect blocks to be number in
1963 sequential order so insert the new block immediately after the
1964 block being split.. */
1965 j = new_edge->src->index;
1966 for (i = n_basic_blocks - 1; i > j + 1; --i)
1968 basic_block tmp = BASIC_BLOCK (i - 1);
1969 BASIC_BLOCK (i) = tmp;
1973 BASIC_BLOCK (i) = new_bb;
1976 /* Create the basic block note. */
1977 bb_note = emit_note_after (NOTE_INSN_BASIC_BLOCK, new_bb->head);
1978 NOTE_BASIC_BLOCK (bb_note) = new_bb;
1979 new_bb->head = bb_note;
1981 new_bb->end = emit_jump_insn_after (gen_jump (label), new_bb->head);
1982 JUMP_LABEL (new_bb->end) = label;
1983 LABEL_NUSES (label)++;
1984 if (basic_block_for_insn)
1985 set_block_for_insn (new_bb->end, new_bb);
1986 emit_barrier_after (new_bb->end);
1990 /* Split a (typically critical) edge. Return the new block.
1991 Abort on abnormal edges.
1993 ??? The code generally expects to be called on critical edges.
1994 The case of a block ending in an unconditional jump to a
1995 block with multiple predecessors is not handled optimally. */
1998 split_edge (edge_in)
2001 basic_block old_pred, bb, old_succ;
2006 /* Abnormal edges cannot be split. */
2007 if ((edge_in->flags & EDGE_ABNORMAL) != 0)
2010 old_pred = edge_in->src;
2011 old_succ = edge_in->dest;
2013 /* Create the new structures. */
2014 bb = (basic_block) obstack_alloc (&flow_obstack, sizeof (*bb));
2015 edge_out = (edge) xcalloc (1, sizeof (*edge_out));
2018 memset (bb, 0, sizeof (*bb));
2020 /* ??? This info is likely going to be out of date very soon. */
2021 if (old_succ->global_live_at_start)
2023 bb->global_live_at_start = OBSTACK_ALLOC_REG_SET (&flow_obstack);
2024 bb->global_live_at_end = OBSTACK_ALLOC_REG_SET (&flow_obstack);
2025 COPY_REG_SET (bb->global_live_at_start, old_succ->global_live_at_start);
2026 COPY_REG_SET (bb->global_live_at_end, old_succ->global_live_at_start);
2030 bb->succ = edge_out;
2031 bb->count = edge_in->count;
2032 bb->frequency = (edge_in->probability * edge_in->src->frequency
2033 / REG_BR_PROB_BASE);
2035 edge_in->flags &= ~EDGE_CRITICAL;
2037 edge_out->pred_next = old_succ->pred;
2038 edge_out->succ_next = NULL;
2040 edge_out->dest = old_succ;
2041 edge_out->flags = EDGE_FALLTHRU;
2042 edge_out->probability = REG_BR_PROB_BASE;
2043 edge_out->count = edge_in->count;
2045 old_succ->pred = edge_out;
2047 /* Tricky case -- if there existed a fallthru into the successor
2048 (and we're not it) we must add a new unconditional jump around
2049 the new block we're actually interested in.
2051 Further, if that edge is critical, this means a second new basic
2052 block must be created to hold it. In order to simplify correct
2053 insn placement, do this before we touch the existing basic block
2054 ordering for the block we were really wanting. */
2055 if ((edge_in->flags & EDGE_FALLTHRU) == 0)
2058 for (e = edge_out->pred_next; e; e = e->pred_next)
2059 if (e->flags & EDGE_FALLTHRU)
2064 basic_block jump_block;
2067 if ((e->flags & EDGE_CRITICAL) == 0
2068 && e->src != ENTRY_BLOCK_PTR)
2070 /* Non critical -- we can simply add a jump to the end
2071 of the existing predecessor. */
2072 jump_block = e->src;
2076 /* We need a new block to hold the jump. The simplest
2077 way to do the bulk of the work here is to recursively
2079 jump_block = split_edge (e);
2080 e = jump_block->succ;
2083 /* Now add the jump insn ... */
2084 pos = emit_jump_insn_after (gen_jump (old_succ->head),
2086 jump_block->end = pos;
2087 if (basic_block_for_insn)
2088 set_block_for_insn (pos, jump_block);
2089 emit_barrier_after (pos);
2091 /* ... let jump know that label is in use, ... */
2092 JUMP_LABEL (pos) = old_succ->head;
2093 ++LABEL_NUSES (old_succ->head);
2095 /* ... and clear fallthru on the outgoing edge. */
2096 e->flags &= ~EDGE_FALLTHRU;
2098 /* Continue splitting the interesting edge. */
2102 /* Place the new block just in front of the successor. */
2103 VARRAY_GROW (basic_block_info, ++n_basic_blocks);
2104 if (old_succ == EXIT_BLOCK_PTR)
2105 j = n_basic_blocks - 1;
2107 j = old_succ->index;
2108 for (i = n_basic_blocks - 1; i > j; --i)
2110 basic_block tmp = BASIC_BLOCK (i - 1);
2111 BASIC_BLOCK (i) = tmp;
2114 BASIC_BLOCK (i) = bb;
2117 /* Create the basic block note.
2119 Where we place the note can have a noticable impact on the generated
2120 code. Consider this cfg:
2130 If we need to insert an insn on the edge from block 0 to block 1,
2131 we want to ensure the instructions we insert are outside of any
2132 loop notes that physically sit between block 0 and block 1. Otherwise
2133 we confuse the loop optimizer into thinking the loop is a phony. */
2134 if (old_succ != EXIT_BLOCK_PTR
2135 && PREV_INSN (old_succ->head)
2136 && GET_CODE (PREV_INSN (old_succ->head)) == NOTE
2137 && NOTE_LINE_NUMBER (PREV_INSN (old_succ->head)) == NOTE_INSN_LOOP_BEG)
2138 bb_note = emit_note_before (NOTE_INSN_BASIC_BLOCK,
2139 PREV_INSN (old_succ->head));
2140 else if (old_succ != EXIT_BLOCK_PTR)
2141 bb_note = emit_note_before (NOTE_INSN_BASIC_BLOCK, old_succ->head);
2143 bb_note = emit_note_after (NOTE_INSN_BASIC_BLOCK, get_last_insn ());
2144 NOTE_BASIC_BLOCK (bb_note) = bb;
2145 bb->head = bb->end = bb_note;
2147 /* For non-fallthry edges, we must adjust the predecessor's
2148 jump instruction to target our new block. */
2149 if ((edge_in->flags & EDGE_FALLTHRU) == 0)
2151 if (!redirect_edge_and_branch (edge_in, bb))
2155 redirect_edge_succ (edge_in, bb);
2160 /* Queue instructions for insertion on an edge between two basic blocks.
2161 The new instructions and basic blocks (if any) will not appear in the
2162 CFG until commit_edge_insertions is called. */
2165 insert_insn_on_edge (pattern, e)
2169 /* We cannot insert instructions on an abnormal critical edge.
2170 It will be easier to find the culprit if we die now. */
2171 if ((e->flags & (EDGE_ABNORMAL|EDGE_CRITICAL))
2172 == (EDGE_ABNORMAL|EDGE_CRITICAL))
2175 if (e->insns == NULL_RTX)
2178 push_to_sequence (e->insns);
2180 emit_insn (pattern);
2182 e->insns = get_insns ();
2186 /* Update the CFG for the instructions queued on edge E. */
2189 commit_one_edge_insertion (e)
2192 rtx before = NULL_RTX, after = NULL_RTX, insns, tmp, last;
2195 /* Pull the insns off the edge now since the edge might go away. */
2197 e->insns = NULL_RTX;
2199 /* Figure out where to put these things. If the destination has
2200 one predecessor, insert there. Except for the exit block. */
2201 if (e->dest->pred->pred_next == NULL
2202 && e->dest != EXIT_BLOCK_PTR)
2206 /* Get the location correct wrt a code label, and "nice" wrt
2207 a basic block note, and before everything else. */
2209 if (GET_CODE (tmp) == CODE_LABEL)
2210 tmp = NEXT_INSN (tmp);
2211 if (NOTE_INSN_BASIC_BLOCK_P (tmp))
2212 tmp = NEXT_INSN (tmp);
2213 if (tmp == bb->head)
2216 after = PREV_INSN (tmp);
2219 /* If the source has one successor and the edge is not abnormal,
2220 insert there. Except for the entry block. */
2221 else if ((e->flags & EDGE_ABNORMAL) == 0
2222 && e->src->succ->succ_next == NULL
2223 && e->src != ENTRY_BLOCK_PTR)
2226 /* It is possible to have a non-simple jump here. Consider a target
2227 where some forms of unconditional jumps clobber a register. This
2228 happens on the fr30 for example.
2230 We know this block has a single successor, so we can just emit
2231 the queued insns before the jump. */
2232 if (GET_CODE (bb->end) == JUMP_INSN)
2238 /* We'd better be fallthru, or we've lost track of what's what. */
2239 if ((e->flags & EDGE_FALLTHRU) == 0)
2246 /* Otherwise we must split the edge. */
2249 bb = split_edge (e);
2253 /* Now that we've found the spot, do the insertion. */
2255 /* Set the new block number for these insns, if structure is allocated. */
2256 if (basic_block_for_insn)
2259 for (i = insns; i != NULL_RTX; i = NEXT_INSN (i))
2260 set_block_for_insn (i, bb);
2265 emit_insns_before (insns, before);
2266 if (before == bb->head)
2269 last = prev_nonnote_insn (before);
2273 last = emit_insns_after (insns, after);
2274 if (after == bb->end)
2278 if (returnjump_p (last))
2280 /* ??? Remove all outgoing edges from BB and add one for EXIT.
2281 This is not currently a problem because this only happens
2282 for the (single) epilogue, which already has a fallthru edge
2286 if (e->dest != EXIT_BLOCK_PTR
2287 || e->succ_next != NULL
2288 || (e->flags & EDGE_FALLTHRU) == 0)
2290 e->flags &= ~EDGE_FALLTHRU;
2292 emit_barrier_after (last);
2296 flow_delete_insn (before);
2298 else if (GET_CODE (last) == JUMP_INSN)
2300 find_sub_basic_blocks (bb);
2303 /* Update the CFG for all queued instructions. */
2306 commit_edge_insertions ()
2311 #ifdef ENABLE_CHECKING
2312 verify_flow_info ();
2316 bb = ENTRY_BLOCK_PTR;
2321 for (e = bb->succ; e; e = next)
2323 next = e->succ_next;
2325 commit_one_edge_insertion (e);
2328 if (++i >= n_basic_blocks)
2330 bb = BASIC_BLOCK (i);
2334 /* Add fake edges to the function exit for any non constant calls in
2335 the bitmap of blocks specified by BLOCKS or to the whole CFG if
2336 BLOCKS is zero. Return the nuber of blocks that were split. */
2339 flow_call_edges_add (blocks)
2343 int blocks_split = 0;
2347 /* Map bb indicies into basic block pointers since split_block
2348 will renumber the basic blocks. */
2350 bbs = xmalloc (n_basic_blocks * sizeof (*bbs));
2354 for (i = 0; i < n_basic_blocks; i++)
2355 bbs[bb_num++] = BASIC_BLOCK (i);
2359 EXECUTE_IF_SET_IN_SBITMAP (blocks, 0, i,
2361 bbs[bb_num++] = BASIC_BLOCK (i);
2366 /* Now add fake edges to the function exit for any non constant
2367 calls since there is no way that we can determine if they will
2370 for (i = 0; i < bb_num; i++)
2372 basic_block bb = bbs[i];
2376 for (insn = bb->end; ; insn = prev_insn)
2378 prev_insn = PREV_INSN (insn);
2379 if (GET_CODE (insn) == CALL_INSN && ! CONST_CALL_P (insn))
2383 /* Note that the following may create a new basic block
2384 and renumber the existing basic blocks. */
2385 e = split_block (bb, insn);
2389 make_edge (NULL, bb, EXIT_BLOCK_PTR, EDGE_FAKE);
2391 if (insn == bb->head)
2397 verify_flow_info ();
2400 return blocks_split;
2403 /* Find unreachable blocks. An unreachable block will have NULL in
2404 block->aux, a non-NULL value indicates the block is reachable. */
2407 find_unreachable_blocks ()
2411 basic_block *tos, *worklist;
2414 tos = worklist = (basic_block *) xmalloc (sizeof (basic_block) * n);
2416 /* Use basic_block->aux as a marker. Clear them all. */
2418 for (i = 0; i < n; ++i)
2419 BASIC_BLOCK (i)->aux = NULL;
2421 /* Add our starting points to the worklist. Almost always there will
2422 be only one. It isn't inconcievable that we might one day directly
2423 support Fortran alternate entry points. */
2425 for (e = ENTRY_BLOCK_PTR->succ; e; e = e->succ_next)
2429 /* Mark the block with a handy non-null value. */
2433 /* Iterate: find everything reachable from what we've already seen. */
2435 while (tos != worklist)
2437 basic_block b = *--tos;
2439 for (e = b->succ; e; e = e->succ_next)
2450 /* Delete all unreachable basic blocks. */
2452 delete_unreachable_blocks ()
2456 find_unreachable_blocks ();
2458 /* Delete all unreachable basic blocks. Count down so that we
2459 don't interfere with the block renumbering that happens in
2460 flow_delete_block. */
2462 for (i = n_basic_blocks - 1; i >= 0; --i)
2464 basic_block b = BASIC_BLOCK (i);
2467 /* This block was found. Tidy up the mark. */
2470 flow_delete_block (b);
2473 tidy_fallthru_edges ();
2476 /* Return true if NOTE is not one of the ones that must be kept paired,
2477 so that we may simply delete them. */
2480 can_delete_note_p (note)
2483 return (NOTE_LINE_NUMBER (note) == NOTE_INSN_DELETED
2484 || NOTE_LINE_NUMBER (note) == NOTE_INSN_BASIC_BLOCK);
2487 /* Unlink a chain of insns between START and FINISH, leaving notes
2488 that must be paired. */
2491 flow_delete_insn_chain (start, finish)
2494 /* Unchain the insns one by one. It would be quicker to delete all
2495 of these with a single unchaining, rather than one at a time, but
2496 we need to keep the NOTE's. */
2502 next = NEXT_INSN (start);
2503 if (GET_CODE (start) == NOTE && !can_delete_note_p (start))
2505 else if (GET_CODE (start) == CODE_LABEL
2506 && ! can_delete_label_p (start))
2508 const char *name = LABEL_NAME (start);
2509 PUT_CODE (start, NOTE);
2510 NOTE_LINE_NUMBER (start) = NOTE_INSN_DELETED_LABEL;
2511 NOTE_SOURCE_FILE (start) = name;
2514 next = flow_delete_insn (start);
2516 if (start == finish)
2522 /* Delete the insns in a (non-live) block. We physically delete every
2523 non-deleted-note insn, and update the flow graph appropriately.
2525 Return nonzero if we deleted an exception handler. */
2527 /* ??? Preserving all such notes strikes me as wrong. It would be nice
2528 to post-process the stream to remove empty blocks, loops, ranges, etc. */
2531 flow_delete_block (b)
2534 int deleted_handler = 0;
2537 /* If the head of this block is a CODE_LABEL, then it might be the
2538 label for an exception handler which can't be reached.
2540 We need to remove the label from the exception_handler_label list
2541 and remove the associated NOTE_INSN_EH_REGION_BEG and
2542 NOTE_INSN_EH_REGION_END notes. */
2546 never_reached_warning (insn);
2548 if (GET_CODE (insn) == CODE_LABEL)
2549 maybe_remove_eh_handler (insn);
2551 /* Include any jump table following the basic block. */
2553 if (GET_CODE (end) == JUMP_INSN
2554 && (tmp = JUMP_LABEL (end)) != NULL_RTX
2555 && (tmp = NEXT_INSN (tmp)) != NULL_RTX
2556 && GET_CODE (tmp) == JUMP_INSN
2557 && (GET_CODE (PATTERN (tmp)) == ADDR_VEC
2558 || GET_CODE (PATTERN (tmp)) == ADDR_DIFF_VEC))
2561 /* Include any barrier that may follow the basic block. */
2562 tmp = next_nonnote_insn (end);
2563 if (tmp && GET_CODE (tmp) == BARRIER)
2566 /* Selectively delete the entire chain. */
2567 flow_delete_insn_chain (insn, end);
2569 /* Remove the edges into and out of this block. Note that there may
2570 indeed be edges in, if we are removing an unreachable loop. */
2574 for (e = b->pred; e; e = next)
2576 for (q = &e->src->succ; *q != e; q = &(*q)->succ_next)
2579 next = e->pred_next;
2583 for (e = b->succ; e; e = next)
2585 for (q = &e->dest->pred; *q != e; q = &(*q)->pred_next)
2588 next = e->succ_next;
2597 /* Remove the basic block from the array, and compact behind it. */
2600 return deleted_handler;
2603 /* Remove block B from the basic block array and compact behind it. */
2609 int i, n = n_basic_blocks;
2611 for (i = b->index; i + 1 < n; ++i)
2613 basic_block x = BASIC_BLOCK (i + 1);
2614 BASIC_BLOCK (i) = x;
2618 basic_block_info->num_elements--;
2622 /* Delete INSN by patching it out. Return the next insn. */
2625 flow_delete_insn (insn)
2628 rtx prev = PREV_INSN (insn);
2629 rtx next = NEXT_INSN (insn);
2632 PREV_INSN (insn) = NULL_RTX;
2633 NEXT_INSN (insn) = NULL_RTX;
2634 INSN_DELETED_P (insn) = 1;
2637 NEXT_INSN (prev) = next;
2639 PREV_INSN (next) = prev;
2641 set_last_insn (prev);
2643 if (GET_CODE (insn) == CODE_LABEL)
2644 remove_node_from_expr_list (insn, &nonlocal_goto_handler_labels);
2646 /* If deleting a jump, decrement the use count of the label. Deleting
2647 the label itself should happen in the normal course of block merging. */
2648 if (GET_CODE (insn) == JUMP_INSN
2649 && JUMP_LABEL (insn)
2650 && GET_CODE (JUMP_LABEL (insn)) == CODE_LABEL)
2651 LABEL_NUSES (JUMP_LABEL (insn))--;
2653 /* Also if deleting an insn that references a label. */
2654 else if ((note = find_reg_note (insn, REG_LABEL, NULL_RTX)) != NULL_RTX
2655 && GET_CODE (XEXP (note, 0)) == CODE_LABEL)
2656 LABEL_NUSES (XEXP (note, 0))--;
2658 if (GET_CODE (insn) == JUMP_INSN
2659 && (GET_CODE (PATTERN (insn)) == ADDR_VEC
2660 || GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC))
2662 rtx pat = PATTERN (insn);
2663 int diff_vec_p = GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC;
2664 int len = XVECLEN (pat, diff_vec_p);
2667 for (i = 0; i < len; i++)
2668 LABEL_NUSES (XEXP (XVECEXP (pat, diff_vec_p, i), 0))--;
2674 /* True if a given label can be deleted. */
2677 can_delete_label_p (label)
2682 if (LABEL_PRESERVE_P (label))
2685 for (x = forced_labels; x; x = XEXP (x, 1))
2686 if (label == XEXP (x, 0))
2688 for (x = label_value_list; x; x = XEXP (x, 1))
2689 if (label == XEXP (x, 0))
2691 for (x = exception_handler_labels; x; x = XEXP (x, 1))
2692 if (label == XEXP (x, 0))
2695 /* User declared labels must be preserved. */
2696 if (LABEL_NAME (label) != 0)
2703 tail_recursion_label_p (label)
2708 for (x = tail_recursion_label_list; x; x = XEXP (x, 1))
2709 if (label == XEXP (x, 0))
2715 /* Blocks A and B are to be merged into a single block A. The insns
2716 are already contiguous, hence `nomove'. */
2719 merge_blocks_nomove (a, b)
2723 rtx b_head, b_end, a_end;
2724 rtx del_first = NULL_RTX, del_last = NULL_RTX;
2727 /* If there was a CODE_LABEL beginning B, delete it. */
2730 if (GET_CODE (b_head) == CODE_LABEL)
2732 /* Detect basic blocks with nothing but a label. This can happen
2733 in particular at the end of a function. */
2734 if (b_head == b_end)
2736 del_first = del_last = b_head;
2737 b_head = NEXT_INSN (b_head);
2740 /* Delete the basic block note. */
2741 if (NOTE_INSN_BASIC_BLOCK_P (b_head))
2743 if (b_head == b_end)
2748 b_head = NEXT_INSN (b_head);
2751 /* If there was a jump out of A, delete it. */
2753 if (GET_CODE (a_end) == JUMP_INSN)
2757 for (prev = PREV_INSN (a_end); ; prev = PREV_INSN (prev))
2758 if (GET_CODE (prev) != NOTE
2759 || NOTE_LINE_NUMBER (prev) == NOTE_INSN_BASIC_BLOCK
2766 /* If this was a conditional jump, we need to also delete
2767 the insn that set cc0. */
2768 if (prev && sets_cc0_p (prev))
2771 prev = prev_nonnote_insn (prev);
2780 else if (GET_CODE (NEXT_INSN (a_end)) == BARRIER)
2781 del_first = NEXT_INSN (a_end);
2783 /* Delete everything marked above as well as crap that might be
2784 hanging out between the two blocks. */
2785 flow_delete_insn_chain (del_first, del_last);
2787 /* Normally there should only be one successor of A and that is B, but
2788 partway though the merge of blocks for conditional_execution we'll
2789 be merging a TEST block with THEN and ELSE successors. Free the
2790 whole lot of them and hope the caller knows what they're doing. */
2792 remove_edge (a->succ);
2794 /* Adjust the edges out of B for the new owner. */
2795 for (e = b->succ; e; e = e->succ_next)
2799 /* B hasn't quite yet ceased to exist. Attempt to prevent mishap. */
2800 b->pred = b->succ = NULL;
2802 /* Reassociate the insns of B with A. */
2805 if (basic_block_for_insn)
2807 BLOCK_FOR_INSN (b_head) = a;
2808 while (b_head != b_end)
2810 b_head = NEXT_INSN (b_head);
2811 BLOCK_FOR_INSN (b_head) = a;
2821 /* Blocks A and B are to be merged into a single block. A has no incoming
2822 fallthru edge, so it can be moved before B without adding or modifying
2823 any jumps (aside from the jump from A to B). */
2826 merge_blocks_move_predecessor_nojumps (a, b)
2829 rtx start, end, barrier;
2835 barrier = next_nonnote_insn (end);
2836 if (GET_CODE (barrier) != BARRIER)
2838 flow_delete_insn (barrier);
2840 /* Move block and loop notes out of the chain so that we do not
2841 disturb their order.
2843 ??? A better solution would be to squeeze out all the non-nested notes
2844 and adjust the block trees appropriately. Even better would be to have
2845 a tighter connection between block trees and rtl so that this is not
2847 start = squeeze_notes (start, end);
2849 /* Scramble the insn chain. */
2850 if (end != PREV_INSN (b->head))
2851 reorder_insns (start, end, PREV_INSN (b->head));
2855 fprintf (rtl_dump_file, "Moved block %d before %d and merged.\n",
2856 a->index, b->index);
2859 /* Swap the records for the two blocks around. Although we are deleting B,
2860 A is now where B was and we want to compact the BB array from where
2862 BASIC_BLOCK (a->index) = b;
2863 BASIC_BLOCK (b->index) = a;
2865 a->index = b->index;
2868 /* Now blocks A and B are contiguous. Merge them. */
2869 merge_blocks_nomove (a, b);
2874 /* Blocks A and B are to be merged into a single block. B has no outgoing
2875 fallthru edge, so it can be moved after A without adding or modifying
2876 any jumps (aside from the jump from A to B). */
2879 merge_blocks_move_successor_nojumps (a, b)
2882 rtx start, end, barrier;
2886 barrier = NEXT_INSN (end);
2888 /* Recognize a jump table following block B. */
2889 if (GET_CODE (barrier) == CODE_LABEL
2890 && NEXT_INSN (barrier)
2891 && GET_CODE (NEXT_INSN (barrier)) == JUMP_INSN
2892 && (GET_CODE (PATTERN (NEXT_INSN (barrier))) == ADDR_VEC
2893 || GET_CODE (PATTERN (NEXT_INSN (barrier))) == ADDR_DIFF_VEC))
2895 end = NEXT_INSN (barrier);
2896 barrier = NEXT_INSN (end);
2899 /* There had better have been a barrier there. Delete it. */
2900 if (GET_CODE (barrier) != BARRIER)
2902 flow_delete_insn (barrier);
2904 /* Move block and loop notes out of the chain so that we do not
2905 disturb their order.
2907 ??? A better solution would be to squeeze out all the non-nested notes
2908 and adjust the block trees appropriately. Even better would be to have
2909 a tighter connection between block trees and rtl so that this is not
2911 start = squeeze_notes (start, end);
2913 /* Scramble the insn chain. */
2914 reorder_insns (start, end, a->end);
2916 /* Now blocks A and B are contiguous. Merge them. */
2917 merge_blocks_nomove (a, b);
2921 fprintf (rtl_dump_file, "Moved block %d after %d and merged.\n",
2922 b->index, a->index);
2928 /* Attempt to merge basic blocks that are potentially non-adjacent.
2929 Return true iff the attempt succeeded. */
2932 merge_blocks (e, b, c)
2936 /* If C has a tail recursion label, do not merge. There is no
2937 edge recorded from the call_placeholder back to this label, as
2938 that would make optimize_sibling_and_tail_recursive_calls more
2939 complex for no gain. */
2940 if (GET_CODE (c->head) == CODE_LABEL
2941 && tail_recursion_label_p (c->head))
2944 /* If B has a fallthru edge to C, no need to move anything. */
2945 if (e->flags & EDGE_FALLTHRU)
2947 merge_blocks_nomove (b, c);
2951 fprintf (rtl_dump_file, "Merged %d and %d without moving.\n",
2952 b->index, c->index);
2960 int c_has_outgoing_fallthru;
2961 int b_has_incoming_fallthru;
2963 /* We must make sure to not munge nesting of exception regions,
2964 lexical blocks, and loop notes.
2966 The first is taken care of by requiring that the active eh
2967 region at the end of one block always matches the active eh
2968 region at the beginning of the next block.
2970 The later two are taken care of by squeezing out all the notes. */
2972 /* ??? A throw/catch edge (or any abnormal edge) should be rarely
2973 executed and we may want to treat blocks which have two out
2974 edges, one normal, one abnormal as only having one edge for
2975 block merging purposes. */
2977 for (tmp_edge = c->succ; tmp_edge; tmp_edge = tmp_edge->succ_next)
2978 if (tmp_edge->flags & EDGE_FALLTHRU)
2980 c_has_outgoing_fallthru = (tmp_edge != NULL);
2982 for (tmp_edge = b->pred; tmp_edge; tmp_edge = tmp_edge->pred_next)
2983 if (tmp_edge->flags & EDGE_FALLTHRU)
2985 b_has_incoming_fallthru = (tmp_edge != NULL);
2987 /* If B does not have an incoming fallthru, then it can be moved
2988 immediately before C without introducing or modifying jumps.
2989 C cannot be the first block, so we do not have to worry about
2990 accessing a non-existent block. */
2991 if (! b_has_incoming_fallthru)
2992 return merge_blocks_move_predecessor_nojumps (b, c);
2994 /* Otherwise, we're going to try to move C after B. If C does
2995 not have an outgoing fallthru, then it can be moved
2996 immediately after B without introducing or modifying jumps. */
2997 if (! c_has_outgoing_fallthru)
2998 return merge_blocks_move_successor_nojumps (b, c);
3000 /* Otherwise, we'll need to insert an extra jump, and possibly
3001 a new block to contain it. */
3002 /* ??? Not implemented yet. */
3008 /* Simplify conditional jump around an jump.
3009 Return nonzero in case optimization matched. */
3012 try_simplify_condjump (src)
3015 basic_block final_block, next_block;
3016 rtx insn = src->end;
3017 edge branch, fallthru;
3019 /* Verify that there are exactly two successors. */
3020 if (!src->succ || !src->succ->succ_next || src->succ->succ_next->succ_next
3021 || !any_condjump_p (insn))
3024 fallthru = FALLTHRU_EDGE (src);
3026 /* Following block must be simple forwarder block with single
3027 entry and must not be last in the stream. */
3028 next_block = fallthru->dest;
3029 if (!forwarder_block_p (next_block)
3030 || next_block->pred->pred_next
3031 || next_block->index == n_basic_blocks - 1)
3034 /* The branch must target to block afterwards. */
3035 final_block = BASIC_BLOCK (next_block->index + 1);
3037 branch = BRANCH_EDGE (src);
3039 if (branch->dest != final_block)
3042 /* Avoid jump.c from being overactive on removin ureachable insns. */
3043 LABEL_NUSES (JUMP_LABEL (insn))++;
3044 if (!invert_jump (insn, block_label (next_block->succ->dest), 1))
3046 LABEL_NUSES (JUMP_LABEL (insn))--;
3050 fprintf (rtl_dump_file, "Simplifying condjump %i around jump %i\n",
3051 INSN_UID (insn), INSN_UID (next_block->end));
3053 redirect_edge_succ (branch, final_block);
3054 redirect_edge_succ (fallthru, next_block->succ->dest);
3056 branch->flags |= EDGE_FALLTHRU;
3057 fallthru->flags &= ~EDGE_FALLTHRU;
3059 flow_delete_block (next_block);
3063 /* Attempt to forward edges leaving basic block B.
3064 Return nonzero if sucessfull. */
3067 try_forward_edges (b)
3072 for (e = b->succ; e; e = e->succ_next)
3074 basic_block target = e->dest, first = e->dest;
3077 /* Look for the real destination of jump.
3078 Avoid inifinite loop in the infinite empty loop by counting
3079 up to n_basic_blocks. */
3080 while (forwarder_block_p (target)
3081 && target->succ->dest != EXIT_BLOCK_PTR
3082 && counter < n_basic_blocks)
3084 /* Bypass trivial infinite loops. */
3085 if (target == target->succ->dest)
3086 counter = n_basic_blocks;
3087 target = target->succ->dest, counter++;
3090 if (target != first && counter < n_basic_blocks
3091 && redirect_edge_and_branch (e, target))
3093 while (first != target)
3095 first->count -= e->count;
3096 first->succ->count -= e->count;
3097 first->frequency -= ((e->probability * b->frequency
3098 + REG_BR_PROB_BASE / 2)
3099 / REG_BR_PROB_BASE);
3100 first = first->succ->dest;
3102 /* We've possibly removed the edge. */
3106 else if (rtl_dump_file && counter == n_basic_blocks)
3107 fprintf (rtl_dump_file, "Infinite loop in BB %i.\n", target->index);
3108 else if (rtl_dump_file && first != target)
3109 fprintf (rtl_dump_file,
3110 "Forwarding edge %i->%i to %i failed.\n", b->index,
3111 e->dest->index, target->index);
3116 /* Do simple CFG optimizations - basic block merging, simplifying of jump
3119 Return nonzero in case some optimizations matched. */
3125 bool changed_overall = 0;
3128 /* Attempt to merge blocks as made possible by edge removal. If a block
3129 has only one successor, and the successor has only one predecessor,
3130 they may be combined. */
3135 for (i = 0; i < n_basic_blocks;)
3137 basic_block c, b = BASIC_BLOCK (i);
3139 int changed_here = 0;
3141 /* Delete trivially dead basic block. */
3142 if (b->pred == NULL)
3144 c = BASIC_BLOCK (i - 1);
3146 fprintf (rtl_dump_file, "Deleting block %i.\n", b->index);
3147 flow_delete_block (b);
3151 /* The fallthru forwarder block can be deleted. */
3152 if (b->pred->pred_next == NULL
3153 && forwarder_block_p (b)
3154 && n_basic_blocks > 1
3155 && (b->pred->flags & EDGE_FALLTHRU)
3156 && (b->succ->flags & EDGE_FALLTHRU))
3159 fprintf (rtl_dump_file, "Deleting fallthru block %i.\n",
3161 c = BASIC_BLOCK (i ? i - 1 : i + 1);
3162 redirect_edge_succ (b->pred, b->succ->dest);
3163 flow_delete_block (b);
3168 /* A loop because chains of blocks might be combineable. */
3169 while ((s = b->succ) != NULL
3170 && s->succ_next == NULL
3171 && (s->flags & EDGE_EH) == 0
3172 && (c = s->dest) != EXIT_BLOCK_PTR
3173 && c->pred->pred_next == NULL
3174 /* If the jump insn has side effects, we can't kill the edge. */
3175 && (GET_CODE (b->end) != JUMP_INSN
3176 || onlyjump_p (b->end)) && merge_blocks (s, b, c))
3179 if (try_simplify_condjump (b))
3182 /* In the case basic blocks has single outgoing edge, but over by the
3183 non-trivial jump instruction, we can replace it by unconditional
3184 jump, or delete the jump completely. Use logic of
3185 redirect_edge_and_branch to do the dirty job for us.
3187 We match cases as conditional jumps jumping to the next block or
3191 && b->succ->succ_next == NULL
3192 && GET_CODE (b->end) == JUMP_INSN
3193 && b->succ->dest != EXIT_BLOCK_PTR
3194 && redirect_edge_and_branch (b->succ, b->succ->dest))
3197 if (try_forward_edges (b))
3200 /* Don't get confused by the index shift caused by deleting
3207 changed_overall |= changed;
3211 #ifdef ENABLE_CHECKING
3213 verify_flow_info ();
3215 return changed_overall;
3218 /* The given edge should potentially be a fallthru edge. If that is in
3219 fact true, delete the jump and barriers that are in the way. */
3222 tidy_fallthru_edge (e, b, c)
3228 /* ??? In a late-running flow pass, other folks may have deleted basic
3229 blocks by nopping out blocks, leaving multiple BARRIERs between here
3230 and the target label. They ought to be chastized and fixed.
3232 We can also wind up with a sequence of undeletable labels between
3233 one block and the next.
3235 So search through a sequence of barriers, labels, and notes for
3236 the head of block C and assert that we really do fall through. */
3238 if (next_real_insn (b->end) != next_real_insn (PREV_INSN (c->head)))
3241 /* Remove what will soon cease being the jump insn from the source block.
3242 If block B consisted only of this single jump, turn it into a deleted
3245 if (GET_CODE (q) == JUMP_INSN
3247 && (any_uncondjump_p (q)
3248 || (b->succ == e && e->succ_next == NULL)))
3251 /* If this was a conditional jump, we need to also delete
3252 the insn that set cc0. */
3253 if (any_condjump_p (q) && sets_cc0_p (PREV_INSN (q)))
3260 NOTE_LINE_NUMBER (q) = NOTE_INSN_DELETED;
3261 NOTE_SOURCE_FILE (q) = 0;
3267 /* We don't want a block to end on a line-number note since that has
3268 the potential of changing the code between -g and not -g. */
3269 while (GET_CODE (q) == NOTE && NOTE_LINE_NUMBER (q) >= 0)
3276 /* Selectively unlink the sequence. */
3277 if (q != PREV_INSN (c->head))
3278 flow_delete_insn_chain (NEXT_INSN (q), PREV_INSN (c->head));
3280 e->flags |= EDGE_FALLTHRU;
3283 /* Fix up edges that now fall through, or rather should now fall through
3284 but previously required a jump around now deleted blocks. Simplify
3285 the search by only examining blocks numerically adjacent, since this
3286 is how find_basic_blocks created them. */
3289 tidy_fallthru_edges ()
3293 for (i = 1; i < n_basic_blocks; ++i)
3295 basic_block b = BASIC_BLOCK (i - 1);
3296 basic_block c = BASIC_BLOCK (i);
3299 /* We care about simple conditional or unconditional jumps with
3302 If we had a conditional branch to the next instruction when
3303 find_basic_blocks was called, then there will only be one
3304 out edge for the block which ended with the conditional
3305 branch (since we do not create duplicate edges).
3307 Furthermore, the edge will be marked as a fallthru because we
3308 merge the flags for the duplicate edges. So we do not want to
3309 check that the edge is not a FALLTHRU edge. */
3310 if ((s = b->succ) != NULL
3311 && ! (s->flags & EDGE_COMPLEX)
3312 && s->succ_next == NULL
3314 /* If the jump insn has side effects, we can't tidy the edge. */
3315 && (GET_CODE (b->end) != JUMP_INSN
3316 || onlyjump_p (b->end)))
3317 tidy_fallthru_edge (s, b, c);
3321 /* Perform data flow analysis.
3322 F is the first insn of the function; FLAGS is a set of PROP_* flags
3323 to be used in accumulating flow info. */
3326 life_analysis (f, file, flags)
3331 #ifdef ELIMINABLE_REGS
3333 static struct {int from, to; } eliminables[] = ELIMINABLE_REGS;
3336 /* Record which registers will be eliminated. We use this in
3339 CLEAR_HARD_REG_SET (elim_reg_set);
3341 #ifdef ELIMINABLE_REGS
3342 for (i = 0; i < (int) ARRAY_SIZE (eliminables); i++)
3343 SET_HARD_REG_BIT (elim_reg_set, eliminables[i].from);
3345 SET_HARD_REG_BIT (elim_reg_set, FRAME_POINTER_REGNUM);
3349 flags &= ~(PROP_LOG_LINKS | PROP_AUTOINC);
3351 /* The post-reload life analysis have (on a global basis) the same
3352 registers live as was computed by reload itself. elimination
3353 Otherwise offsets and such may be incorrect.
3355 Reload will make some registers as live even though they do not
3358 We don't want to create new auto-incs after reload, since they
3359 are unlikely to be useful and can cause problems with shared
3361 if (reload_completed)
3362 flags &= ~(PROP_REG_INFO | PROP_AUTOINC);
3364 /* We want alias analysis information for local dead store elimination. */
3365 if (optimize && (flags & PROP_SCAN_DEAD_CODE))
3366 init_alias_analysis ();
3368 /* Always remove no-op moves. Do this before other processing so
3369 that we don't have to keep re-scanning them. */
3370 delete_noop_moves (f);
3372 /* Some targets can emit simpler epilogues if they know that sp was
3373 not ever modified during the function. After reload, of course,
3374 we've already emitted the epilogue so there's no sense searching. */
3375 if (! reload_completed)
3376 notice_stack_pointer_modification (f);
3378 /* Allocate and zero out data structures that will record the
3379 data from lifetime analysis. */
3380 allocate_reg_life_data ();
3381 allocate_bb_life_data ();
3383 /* Find the set of registers live on function exit. */
3384 mark_regs_live_at_end (EXIT_BLOCK_PTR->global_live_at_start);
3386 /* "Update" life info from zero. It'd be nice to begin the
3387 relaxation with just the exit and noreturn blocks, but that set
3388 is not immediately handy. */
3390 if (flags & PROP_REG_INFO)
3391 memset (regs_ever_live, 0, sizeof (regs_ever_live));
3392 update_life_info (NULL, UPDATE_LIFE_GLOBAL, flags);
3395 if (optimize && (flags & PROP_SCAN_DEAD_CODE))
3396 end_alias_analysis ();
3399 dump_flow_info (file);
3401 free_basic_block_vars (1);
3403 #ifdef ENABLE_CHECKING
3407 /* Search for any REG_LABEL notes which reference deleted labels. */
3408 for (insn = get_insns (); insn; insn = NEXT_INSN (insn))
3410 rtx inote = find_reg_note (insn, REG_LABEL, NULL_RTX);
3412 if (inote && GET_CODE (inote) == NOTE_INSN_DELETED_LABEL)
3419 /* A subroutine of verify_wide_reg, called through for_each_rtx.
3420 Search for REGNO. If found, abort if it is not wider than word_mode. */
3423 verify_wide_reg_1 (px, pregno)
3428 unsigned int regno = *(int *) pregno;
3430 if (GET_CODE (x) == REG && REGNO (x) == regno)
3432 if (GET_MODE_BITSIZE (GET_MODE (x)) <= BITS_PER_WORD)
3439 /* A subroutine of verify_local_live_at_start. Search through insns
3440 between HEAD and END looking for register REGNO. */
3443 verify_wide_reg (regno, head, end)
3450 && for_each_rtx (&PATTERN (head), verify_wide_reg_1, ®no))
3454 head = NEXT_INSN (head);
3457 /* We didn't find the register at all. Something's way screwy. */
3459 fprintf (rtl_dump_file, "Aborting in verify_wide_reg; reg %d\n", regno);
3460 print_rtl_and_abort ();
3463 /* A subroutine of update_life_info. Verify that there are no untoward
3464 changes in live_at_start during a local update. */
3467 verify_local_live_at_start (new_live_at_start, bb)
3468 regset new_live_at_start;
3471 if (reload_completed)
3473 /* After reload, there are no pseudos, nor subregs of multi-word
3474 registers. The regsets should exactly match. */
3475 if (! REG_SET_EQUAL_P (new_live_at_start, bb->global_live_at_start))
3479 fprintf (rtl_dump_file,
3480 "live_at_start mismatch in bb %d, aborting\n",
3482 debug_bitmap_file (rtl_dump_file, bb->global_live_at_start);
3483 debug_bitmap_file (rtl_dump_file, new_live_at_start);
3485 print_rtl_and_abort ();
3492 /* Find the set of changed registers. */
3493 XOR_REG_SET (new_live_at_start, bb->global_live_at_start);
3495 EXECUTE_IF_SET_IN_REG_SET (new_live_at_start, 0, i,
3497 /* No registers should die. */
3498 if (REGNO_REG_SET_P (bb->global_live_at_start, i))
3501 fprintf (rtl_dump_file,
3502 "Register %d died unexpectedly in block %d\n", i,
3504 print_rtl_and_abort ();
3507 /* Verify that the now-live register is wider than word_mode. */
3508 verify_wide_reg (i, bb->head, bb->end);
3513 /* Updates life information starting with the basic blocks set in BLOCKS.
3514 If BLOCKS is null, consider it to be the universal set.
3516 If EXTENT is UPDATE_LIFE_LOCAL, such as after splitting or peepholeing,
3517 we are only expecting local modifications to basic blocks. If we find
3518 extra registers live at the beginning of a block, then we either killed
3519 useful data, or we have a broken split that wants data not provided.
3520 If we find registers removed from live_at_start, that means we have
3521 a broken peephole that is killing a register it shouldn't.
3523 ??? This is not true in one situation -- when a pre-reload splitter
3524 generates subregs of a multi-word pseudo, current life analysis will
3525 lose the kill. So we _can_ have a pseudo go live. How irritating.
3527 Including PROP_REG_INFO does not properly refresh regs_ever_live
3528 unless the caller resets it to zero. */
3531 update_life_info (blocks, extent, prop_flags)
3533 enum update_life_extent extent;
3537 regset_head tmp_head;
3540 tmp = INITIALIZE_REG_SET (tmp_head);
3542 /* For a global update, we go through the relaxation process again. */
3543 if (extent != UPDATE_LIFE_LOCAL)
3545 calculate_global_regs_live (blocks, blocks,
3546 prop_flags & PROP_SCAN_DEAD_CODE);
3548 /* If asked, remove notes from the blocks we'll update. */
3549 if (extent == UPDATE_LIFE_GLOBAL_RM_NOTES)
3550 count_or_remove_death_notes (blocks, 1);
3555 EXECUTE_IF_SET_IN_SBITMAP (blocks, 0, i,
3557 basic_block bb = BASIC_BLOCK (i);
3559 COPY_REG_SET (tmp, bb->global_live_at_end);
3560 propagate_block (bb, tmp, NULL, NULL, prop_flags);
3562 if (extent == UPDATE_LIFE_LOCAL)
3563 verify_local_live_at_start (tmp, bb);
3568 for (i = n_basic_blocks - 1; i >= 0; --i)
3570 basic_block bb = BASIC_BLOCK (i);
3572 COPY_REG_SET (tmp, bb->global_live_at_end);
3573 propagate_block (bb, tmp, NULL, NULL, prop_flags);
3575 if (extent == UPDATE_LIFE_LOCAL)
3576 verify_local_live_at_start (tmp, bb);
3582 if (prop_flags & PROP_REG_INFO)
3584 /* The only pseudos that are live at the beginning of the function
3585 are those that were not set anywhere in the function. local-alloc
3586 doesn't know how to handle these correctly, so mark them as not
3587 local to any one basic block. */
3588 EXECUTE_IF_SET_IN_REG_SET (ENTRY_BLOCK_PTR->global_live_at_end,
3589 FIRST_PSEUDO_REGISTER, i,
3590 { REG_BASIC_BLOCK (i) = REG_BLOCK_GLOBAL; });
3592 /* We have a problem with any pseudoreg that lives across the setjmp.
3593 ANSI says that if a user variable does not change in value between
3594 the setjmp and the longjmp, then the longjmp preserves it. This
3595 includes longjmp from a place where the pseudo appears dead.
3596 (In principle, the value still exists if it is in scope.)
3597 If the pseudo goes in a hard reg, some other value may occupy
3598 that hard reg where this pseudo is dead, thus clobbering the pseudo.
3599 Conclusion: such a pseudo must not go in a hard reg. */
3600 EXECUTE_IF_SET_IN_REG_SET (regs_live_at_setjmp,
3601 FIRST_PSEUDO_REGISTER, i,
3603 if (regno_reg_rtx[i] != 0)
3605 REG_LIVE_LENGTH (i) = -1;
3606 REG_BASIC_BLOCK (i) = REG_BLOCK_UNKNOWN;
3612 /* Free the variables allocated by find_basic_blocks.
3614 KEEP_HEAD_END_P is non-zero if basic_block_info is not to be freed. */
3617 free_basic_block_vars (keep_head_end_p)
3618 int keep_head_end_p;
3620 if (basic_block_for_insn)
3622 VARRAY_FREE (basic_block_for_insn);
3623 basic_block_for_insn = NULL;
3626 if (! keep_head_end_p)
3628 if (basic_block_info)
3631 VARRAY_FREE (basic_block_info);
3635 ENTRY_BLOCK_PTR->aux = NULL;
3636 ENTRY_BLOCK_PTR->global_live_at_end = NULL;
3637 EXIT_BLOCK_PTR->aux = NULL;
3638 EXIT_BLOCK_PTR->global_live_at_start = NULL;
3642 /* Return nonzero if an insn consists only of SETs, each of which only sets a
3649 rtx pat = PATTERN (insn);
3651 /* Insns carrying these notes are useful later on. */
3652 if (find_reg_note (insn, REG_EQUAL, NULL_RTX))
3655 if (GET_CODE (pat) == SET && set_noop_p (pat))
3658 if (GET_CODE (pat) == PARALLEL)
3661 /* If nothing but SETs of registers to themselves,
3662 this insn can also be deleted. */
3663 for (i = 0; i < XVECLEN (pat, 0); i++)
3665 rtx tem = XVECEXP (pat, 0, i);
3667 if (GET_CODE (tem) == USE
3668 || GET_CODE (tem) == CLOBBER)
3671 if (GET_CODE (tem) != SET || ! set_noop_p (tem))
3680 /* Delete any insns that copy a register to itself. */
3683 delete_noop_moves (f)
3687 for (insn = f; insn; insn = NEXT_INSN (insn))
3689 if (GET_CODE (insn) == INSN && noop_move_p (insn))
3691 PUT_CODE (insn, NOTE);
3692 NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED;
3693 NOTE_SOURCE_FILE (insn) = 0;
3698 /* Determine if the stack pointer is constant over the life of the function.
3699 Only useful before prologues have been emitted. */
3702 notice_stack_pointer_modification_1 (x, pat, data)
3704 rtx pat ATTRIBUTE_UNUSED;
3705 void *data ATTRIBUTE_UNUSED;
3707 if (x == stack_pointer_rtx
3708 /* The stack pointer is only modified indirectly as the result
3709 of a push until later in flow. See the comments in rtl.texi
3710 regarding Embedded Side-Effects on Addresses. */
3711 || (GET_CODE (x) == MEM
3712 && GET_RTX_CLASS (GET_CODE (XEXP (x, 0))) == 'a'
3713 && XEXP (XEXP (x, 0), 0) == stack_pointer_rtx))
3714 current_function_sp_is_unchanging = 0;
3718 notice_stack_pointer_modification (f)
3723 /* Assume that the stack pointer is unchanging if alloca hasn't
3725 current_function_sp_is_unchanging = !current_function_calls_alloca;
3726 if (! current_function_sp_is_unchanging)
3729 for (insn = f; insn; insn = NEXT_INSN (insn))
3733 /* Check if insn modifies the stack pointer. */
3734 note_stores (PATTERN (insn), notice_stack_pointer_modification_1,
3736 if (! current_function_sp_is_unchanging)
3742 /* Mark a register in SET. Hard registers in large modes get all
3743 of their component registers set as well. */
3746 mark_reg (reg, xset)
3750 regset set = (regset) xset;
3751 int regno = REGNO (reg);
3753 if (GET_MODE (reg) == BLKmode)
3756 SET_REGNO_REG_SET (set, regno);
3757 if (regno < FIRST_PSEUDO_REGISTER)
3759 int n = HARD_REGNO_NREGS (regno, GET_MODE (reg));
3761 SET_REGNO_REG_SET (set, regno + n);
3765 /* Mark those regs which are needed at the end of the function as live
3766 at the end of the last basic block. */
3769 mark_regs_live_at_end (set)
3774 /* If exiting needs the right stack value, consider the stack pointer
3775 live at the end of the function. */
3776 if ((HAVE_epilogue && reload_completed)
3777 || ! EXIT_IGNORE_STACK
3778 || (! FRAME_POINTER_REQUIRED
3779 && ! current_function_calls_alloca
3780 && flag_omit_frame_pointer)
3781 || current_function_sp_is_unchanging)
3783 SET_REGNO_REG_SET (set, STACK_POINTER_REGNUM);
3786 /* Mark the frame pointer if needed at the end of the function. If
3787 we end up eliminating it, it will be removed from the live list
3788 of each basic block by reload. */
3790 if (! reload_completed || frame_pointer_needed)
3792 SET_REGNO_REG_SET (set, FRAME_POINTER_REGNUM);
3793 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
3794 /* If they are different, also mark the hard frame pointer as live. */
3795 if (! LOCAL_REGNO (HARD_FRAME_POINTER_REGNUM))
3796 SET_REGNO_REG_SET (set, HARD_FRAME_POINTER_REGNUM);
3800 #ifndef PIC_OFFSET_TABLE_REG_CALL_CLOBBERED
3801 /* Many architectures have a GP register even without flag_pic.
3802 Assume the pic register is not in use, or will be handled by
3803 other means, if it is not fixed. */
3804 if (PIC_OFFSET_TABLE_REGNUM != INVALID_REGNUM
3805 && fixed_regs[PIC_OFFSET_TABLE_REGNUM])
3806 SET_REGNO_REG_SET (set, PIC_OFFSET_TABLE_REGNUM);
3809 /* Mark all global registers, and all registers used by the epilogue
3810 as being live at the end of the function since they may be
3811 referenced by our caller. */
3812 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
3813 if (global_regs[i] || EPILOGUE_USES (i))
3814 SET_REGNO_REG_SET (set, i);
3816 if (HAVE_epilogue && reload_completed)
3818 /* Mark all call-saved registers that we actually used. */
3819 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
3820 if (regs_ever_live[i] && ! call_used_regs[i] && ! LOCAL_REGNO (i))
3821 SET_REGNO_REG_SET (set, i);
3824 #ifdef EH_RETURN_DATA_REGNO
3825 /* Mark the registers that will contain data for the handler. */
3826 if (reload_completed && current_function_calls_eh_return)
3829 unsigned regno = EH_RETURN_DATA_REGNO(i);
3830 if (regno == INVALID_REGNUM)
3832 SET_REGNO_REG_SET (set, regno);
3835 #ifdef EH_RETURN_STACKADJ_RTX
3836 if ((! HAVE_epilogue || ! reload_completed)
3837 && current_function_calls_eh_return)
3839 rtx tmp = EH_RETURN_STACKADJ_RTX;
3840 if (tmp && REG_P (tmp))
3841 mark_reg (tmp, set);
3844 #ifdef EH_RETURN_HANDLER_RTX
3845 if ((! HAVE_epilogue || ! reload_completed)
3846 && current_function_calls_eh_return)
3848 rtx tmp = EH_RETURN_HANDLER_RTX;
3849 if (tmp && REG_P (tmp))
3850 mark_reg (tmp, set);
3854 /* Mark function return value. */
3855 diddle_return_value (mark_reg, set);
3858 /* Callback function for for_each_successor_phi. DATA is a regset.
3859 Sets the SRC_REGNO, the regno of the phi alternative for phi node
3860 INSN, in the regset. */
3863 set_phi_alternative_reg (insn, dest_regno, src_regno, data)
3864 rtx insn ATTRIBUTE_UNUSED;
3865 int dest_regno ATTRIBUTE_UNUSED;
3869 regset live = (regset) data;
3870 SET_REGNO_REG_SET (live, src_regno);
3874 /* Propagate global life info around the graph of basic blocks. Begin
3875 considering blocks with their corresponding bit set in BLOCKS_IN.
3876 If BLOCKS_IN is null, consider it the universal set.
3878 BLOCKS_OUT is set for every block that was changed. */
3881 calculate_global_regs_live (blocks_in, blocks_out, flags)
3882 sbitmap blocks_in, blocks_out;
3885 basic_block *queue, *qhead, *qtail, *qend;
3886 regset tmp, new_live_at_end, call_used;
3887 regset_head tmp_head, call_used_head;
3888 regset_head new_live_at_end_head;
3891 tmp = INITIALIZE_REG_SET (tmp_head);
3892 new_live_at_end = INITIALIZE_REG_SET (new_live_at_end_head);
3893 call_used = INITIALIZE_REG_SET (call_used_head);
3895 /* Inconveniently, this is only redily available in hard reg set form. */
3896 for (i = 0; i < FIRST_PSEUDO_REGISTER; ++i)
3897 if (call_used_regs[i])
3898 SET_REGNO_REG_SET (call_used, i);
3900 /* Create a worklist. Allocate an extra slot for ENTRY_BLOCK, and one
3901 because the `head == tail' style test for an empty queue doesn't
3902 work with a full queue. */
3903 queue = (basic_block *) xmalloc ((n_basic_blocks + 2) * sizeof (*queue));
3905 qhead = qend = queue + n_basic_blocks + 2;
3907 /* Queue the blocks set in the initial mask. Do this in reverse block
3908 number order so that we are more likely for the first round to do
3909 useful work. We use AUX non-null to flag that the block is queued. */
3912 /* Clear out the garbage that might be hanging out in bb->aux. */
3913 for (i = n_basic_blocks - 1; i >= 0; --i)
3914 BASIC_BLOCK (i)->aux = NULL;
3916 EXECUTE_IF_SET_IN_SBITMAP (blocks_in, 0, i,
3918 basic_block bb = BASIC_BLOCK (i);
3925 for (i = 0; i < n_basic_blocks; ++i)
3927 basic_block bb = BASIC_BLOCK (i);
3934 sbitmap_zero (blocks_out);
3936 /* We work through the queue until there are no more blocks. What
3937 is live at the end of this block is precisely the union of what
3938 is live at the beginning of all its successors. So, we set its
3939 GLOBAL_LIVE_AT_END field based on the GLOBAL_LIVE_AT_START field
3940 for its successors. Then, we compute GLOBAL_LIVE_AT_START for
3941 this block by walking through the instructions in this block in
3942 reverse order and updating as we go. If that changed
3943 GLOBAL_LIVE_AT_START, we add the predecessors of the block to the
3944 queue; they will now need to recalculate GLOBAL_LIVE_AT_END.
3946 We are guaranteed to terminate, because GLOBAL_LIVE_AT_START
3947 never shrinks. If a register appears in GLOBAL_LIVE_AT_START, it
3948 must either be live at the end of the block, or used within the
3949 block. In the latter case, it will certainly never disappear
3950 from GLOBAL_LIVE_AT_START. In the former case, the register
3951 could go away only if it disappeared from GLOBAL_LIVE_AT_START
3952 for one of the successor blocks. By induction, that cannot
3954 while (qhead != qtail)
3956 int rescan, changed;
3965 /* Begin by propagating live_at_start from the successor blocks. */
3966 CLEAR_REG_SET (new_live_at_end);
3967 for (e = bb->succ; e; e = e->succ_next)
3969 basic_block sb = e->dest;
3971 /* Call-clobbered registers die across exception and call edges. */
3972 /* ??? Abnormal call edges ignored for the moment, as this gets
3973 confused by sibling call edges, which crashes reg-stack. */
3974 if (e->flags & EDGE_EH)
3976 bitmap_operation (tmp, sb->global_live_at_start,
3977 call_used, BITMAP_AND_COMPL);
3978 IOR_REG_SET (new_live_at_end, tmp);
3981 IOR_REG_SET (new_live_at_end, sb->global_live_at_start);
3984 /* The all-important stack pointer must always be live. */
3985 SET_REGNO_REG_SET (new_live_at_end, STACK_POINTER_REGNUM);
3987 /* Before reload, there are a few registers that must be forced
3988 live everywhere -- which might not already be the case for
3989 blocks within infinite loops. */
3990 if (! reload_completed)
3992 /* Any reference to any pseudo before reload is a potential
3993 reference of the frame pointer. */
3994 SET_REGNO_REG_SET (new_live_at_end, FRAME_POINTER_REGNUM);
3996 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
3997 /* Pseudos with argument area equivalences may require
3998 reloading via the argument pointer. */
3999 if (fixed_regs[ARG_POINTER_REGNUM])
4000 SET_REGNO_REG_SET (new_live_at_end, ARG_POINTER_REGNUM);
4003 /* Any constant, or pseudo with constant equivalences, may
4004 require reloading from memory using the pic register. */
4005 if (PIC_OFFSET_TABLE_REGNUM != INVALID_REGNUM
4006 && fixed_regs[PIC_OFFSET_TABLE_REGNUM])
4007 SET_REGNO_REG_SET (new_live_at_end, PIC_OFFSET_TABLE_REGNUM);
4010 /* Regs used in phi nodes are not included in
4011 global_live_at_start, since they are live only along a
4012 particular edge. Set those regs that are live because of a
4013 phi node alternative corresponding to this particular block. */
4015 for_each_successor_phi (bb, &set_phi_alternative_reg,
4018 if (bb == ENTRY_BLOCK_PTR)
4020 COPY_REG_SET (bb->global_live_at_end, new_live_at_end);
4024 /* On our first pass through this block, we'll go ahead and continue.
4025 Recognize first pass by local_set NULL. On subsequent passes, we
4026 get to skip out early if live_at_end wouldn't have changed. */
4028 if (bb->local_set == NULL)
4030 bb->local_set = OBSTACK_ALLOC_REG_SET (&flow_obstack);
4031 bb->cond_local_set = OBSTACK_ALLOC_REG_SET (&flow_obstack);
4036 /* If any bits were removed from live_at_end, we'll have to
4037 rescan the block. This wouldn't be necessary if we had
4038 precalculated local_live, however with PROP_SCAN_DEAD_CODE
4039 local_live is really dependent on live_at_end. */
4040 CLEAR_REG_SET (tmp);
4041 rescan = bitmap_operation (tmp, bb->global_live_at_end,
4042 new_live_at_end, BITMAP_AND_COMPL);
4046 /* If any of the registers in the new live_at_end set are
4047 conditionally set in this basic block, we must rescan.
4048 This is because conditional lifetimes at the end of the
4049 block do not just take the live_at_end set into account,
4050 but also the liveness at the start of each successor
4051 block. We can miss changes in those sets if we only
4052 compare the new live_at_end against the previous one. */
4053 CLEAR_REG_SET (tmp);
4054 rescan = bitmap_operation (tmp, new_live_at_end,
4055 bb->cond_local_set, BITMAP_AND);
4060 /* Find the set of changed bits. Take this opportunity
4061 to notice that this set is empty and early out. */
4062 CLEAR_REG_SET (tmp);
4063 changed = bitmap_operation (tmp, bb->global_live_at_end,
4064 new_live_at_end, BITMAP_XOR);
4068 /* If any of the changed bits overlap with local_set,
4069 we'll have to rescan the block. Detect overlap by
4070 the AND with ~local_set turning off bits. */
4071 rescan = bitmap_operation (tmp, tmp, bb->local_set,
4076 /* Let our caller know that BB changed enough to require its
4077 death notes updated. */
4079 SET_BIT (blocks_out, bb->index);
4083 /* Add to live_at_start the set of all registers in
4084 new_live_at_end that aren't in the old live_at_end. */
4086 bitmap_operation (tmp, new_live_at_end, bb->global_live_at_end,
4088 COPY_REG_SET (bb->global_live_at_end, new_live_at_end);
4090 changed = bitmap_operation (bb->global_live_at_start,
4091 bb->global_live_at_start,
4098 COPY_REG_SET (bb->global_live_at_end, new_live_at_end);
4100 /* Rescan the block insn by insn to turn (a copy of) live_at_end
4101 into live_at_start. */
4102 propagate_block (bb, new_live_at_end, bb->local_set,
4103 bb->cond_local_set, flags);
4105 /* If live_at start didn't change, no need to go farther. */
4106 if (REG_SET_EQUAL_P (bb->global_live_at_start, new_live_at_end))
4109 COPY_REG_SET (bb->global_live_at_start, new_live_at_end);
4112 /* Queue all predecessors of BB so that we may re-examine
4113 their live_at_end. */
4114 for (e = bb->pred; e; e = e->pred_next)
4116 basic_block pb = e->src;
4117 if (pb->aux == NULL)
4128 FREE_REG_SET (new_live_at_end);
4129 FREE_REG_SET (call_used);
4133 EXECUTE_IF_SET_IN_SBITMAP (blocks_out, 0, i,
4135 basic_block bb = BASIC_BLOCK (i);
4136 FREE_REG_SET (bb->local_set);
4137 FREE_REG_SET (bb->cond_local_set);
4142 for (i = n_basic_blocks - 1; i >= 0; --i)
4144 basic_block bb = BASIC_BLOCK (i);
4145 FREE_REG_SET (bb->local_set);
4146 FREE_REG_SET (bb->cond_local_set);
4153 /* Subroutines of life analysis. */
4155 /* Allocate the permanent data structures that represent the results
4156 of life analysis. Not static since used also for stupid life analysis. */
4159 allocate_bb_life_data ()
4163 for (i = 0; i < n_basic_blocks; i++)
4165 basic_block bb = BASIC_BLOCK (i);
4167 bb->global_live_at_start = OBSTACK_ALLOC_REG_SET (&flow_obstack);
4168 bb->global_live_at_end = OBSTACK_ALLOC_REG_SET (&flow_obstack);
4171 ENTRY_BLOCK_PTR->global_live_at_end
4172 = OBSTACK_ALLOC_REG_SET (&flow_obstack);
4173 EXIT_BLOCK_PTR->global_live_at_start
4174 = OBSTACK_ALLOC_REG_SET (&flow_obstack);
4176 regs_live_at_setjmp = OBSTACK_ALLOC_REG_SET (&flow_obstack);
4180 allocate_reg_life_data ()
4184 max_regno = max_reg_num ();
4186 /* Recalculate the register space, in case it has grown. Old style
4187 vector oriented regsets would set regset_{size,bytes} here also. */
4188 allocate_reg_info (max_regno, FALSE, FALSE);
4190 /* Reset all the data we'll collect in propagate_block and its
4192 for (i = 0; i < max_regno; i++)
4196 REG_N_DEATHS (i) = 0;
4197 REG_N_CALLS_CROSSED (i) = 0;
4198 REG_LIVE_LENGTH (i) = 0;
4199 REG_BASIC_BLOCK (i) = REG_BLOCK_UNKNOWN;
4203 /* Delete dead instructions for propagate_block. */
4206 propagate_block_delete_insn (bb, insn)
4210 rtx inote = find_reg_note (insn, REG_LABEL, NULL_RTX);
4212 /* If the insn referred to a label, and that label was attached to
4213 an ADDR_VEC, it's safe to delete the ADDR_VEC. In fact, it's
4214 pretty much mandatory to delete it, because the ADDR_VEC may be
4215 referencing labels that no longer exist.
4217 INSN may reference a deleted label, particularly when a jump
4218 table has been optimized into a direct jump. There's no
4219 real good way to fix up the reference to the deleted label
4220 when the label is deleted, so we just allow it here.
4222 After dead code elimination is complete, we do search for
4223 any REG_LABEL notes which reference deleted labels as a
4226 if (inote && GET_CODE (inote) == CODE_LABEL)
4228 rtx label = XEXP (inote, 0);
4231 /* The label may be forced if it has been put in the constant
4232 pool. If that is the only use we must discard the table
4233 jump following it, but not the label itself. */
4234 if (LABEL_NUSES (label) == 1 + LABEL_PRESERVE_P (label)
4235 && (next = next_nonnote_insn (label)) != NULL
4236 && GET_CODE (next) == JUMP_INSN
4237 && (GET_CODE (PATTERN (next)) == ADDR_VEC
4238 || GET_CODE (PATTERN (next)) == ADDR_DIFF_VEC))
4240 rtx pat = PATTERN (next);
4241 int diff_vec_p = GET_CODE (pat) == ADDR_DIFF_VEC;
4242 int len = XVECLEN (pat, diff_vec_p);
4245 for (i = 0; i < len; i++)
4246 LABEL_NUSES (XEXP (XVECEXP (pat, diff_vec_p, i), 0))--;
4248 flow_delete_insn (next);
4252 if (bb->end == insn)
4253 bb->end = PREV_INSN (insn);
4254 flow_delete_insn (insn);
4257 /* Delete dead libcalls for propagate_block. Return the insn
4258 before the libcall. */
4261 propagate_block_delete_libcall (bb, insn, note)
4265 rtx first = XEXP (note, 0);
4266 rtx before = PREV_INSN (first);
4268 if (insn == bb->end)
4271 flow_delete_insn_chain (first, insn);
4275 /* Update the life-status of regs for one insn. Return the previous insn. */
4278 propagate_one_insn (pbi, insn)
4279 struct propagate_block_info *pbi;
4282 rtx prev = PREV_INSN (insn);
4283 int flags = pbi->flags;
4284 int insn_is_dead = 0;
4285 int libcall_is_dead = 0;
4289 if (! INSN_P (insn))
4292 note = find_reg_note (insn, REG_RETVAL, NULL_RTX);
4293 if (flags & PROP_SCAN_DEAD_CODE)
4295 insn_is_dead = insn_dead_p (pbi, PATTERN (insn), 0, REG_NOTES (insn));
4296 libcall_is_dead = (insn_is_dead && note != 0
4297 && libcall_dead_p (pbi, note, insn));
4300 /* If an instruction consists of just dead store(s) on final pass,
4302 if ((flags & PROP_KILL_DEAD_CODE) && insn_is_dead)
4304 /* If we're trying to delete a prologue or epilogue instruction
4305 that isn't flagged as possibly being dead, something is wrong.
4306 But if we are keeping the stack pointer depressed, we might well
4307 be deleting insns that are used to compute the amount to update
4308 it by, so they are fine. */
4309 if (reload_completed
4310 && !(TREE_CODE (TREE_TYPE (current_function_decl)) == FUNCTION_TYPE
4311 && (TYPE_RETURNS_STACK_DEPRESSED
4312 (TREE_TYPE (current_function_decl))))
4313 && (((HAVE_epilogue || HAVE_prologue)
4314 && prologue_epilogue_contains (insn))
4315 || (HAVE_sibcall_epilogue
4316 && sibcall_epilogue_contains (insn)))
4317 && find_reg_note (insn, REG_MAYBE_DEAD, NULL_RTX) == 0)
4320 /* Record sets. Do this even for dead instructions, since they
4321 would have killed the values if they hadn't been deleted. */
4322 mark_set_regs (pbi, PATTERN (insn), insn);
4324 /* CC0 is now known to be dead. Either this insn used it,
4325 in which case it doesn't anymore, or clobbered it,
4326 so the next insn can't use it. */
4329 if (libcall_is_dead)
4330 prev = propagate_block_delete_libcall (pbi->bb, insn, note);
4332 propagate_block_delete_insn (pbi->bb, insn);
4337 /* See if this is an increment or decrement that can be merged into
4338 a following memory address. */
4341 register rtx x = single_set (insn);
4343 /* Does this instruction increment or decrement a register? */
4344 if ((flags & PROP_AUTOINC)
4346 && GET_CODE (SET_DEST (x)) == REG
4347 && (GET_CODE (SET_SRC (x)) == PLUS
4348 || GET_CODE (SET_SRC (x)) == MINUS)
4349 && XEXP (SET_SRC (x), 0) == SET_DEST (x)
4350 && GET_CODE (XEXP (SET_SRC (x), 1)) == CONST_INT
4351 /* Ok, look for a following memory ref we can combine with.
4352 If one is found, change the memory ref to a PRE_INC
4353 or PRE_DEC, cancel this insn, and return 1.
4354 Return 0 if nothing has been done. */
4355 && try_pre_increment_1 (pbi, insn))
4358 #endif /* AUTO_INC_DEC */
4360 CLEAR_REG_SET (pbi->new_set);
4362 /* If this is not the final pass, and this insn is copying the value of
4363 a library call and it's dead, don't scan the insns that perform the
4364 library call, so that the call's arguments are not marked live. */
4365 if (libcall_is_dead)
4367 /* Record the death of the dest reg. */
4368 mark_set_regs (pbi, PATTERN (insn), insn);
4370 insn = XEXP (note, 0);
4371 return PREV_INSN (insn);
4373 else if (GET_CODE (PATTERN (insn)) == SET
4374 && SET_DEST (PATTERN (insn)) == stack_pointer_rtx
4375 && GET_CODE (SET_SRC (PATTERN (insn))) == PLUS
4376 && XEXP (SET_SRC (PATTERN (insn)), 0) == stack_pointer_rtx
4377 && GET_CODE (XEXP (SET_SRC (PATTERN (insn)), 1)) == CONST_INT)
4378 /* We have an insn to pop a constant amount off the stack.
4379 (Such insns use PLUS regardless of the direction of the stack,
4380 and any insn to adjust the stack by a constant is always a pop.)
4381 These insns, if not dead stores, have no effect on life. */
4385 /* Any regs live at the time of a call instruction must not go
4386 in a register clobbered by calls. Find all regs now live and
4387 record this for them. */
4389 if (GET_CODE (insn) == CALL_INSN && (flags & PROP_REG_INFO))
4390 EXECUTE_IF_SET_IN_REG_SET (pbi->reg_live, 0, i,
4391 { REG_N_CALLS_CROSSED (i)++; });
4393 /* Record sets. Do this even for dead instructions, since they
4394 would have killed the values if they hadn't been deleted. */
4395 mark_set_regs (pbi, PATTERN (insn), insn);
4397 if (GET_CODE (insn) == CALL_INSN)
4403 if (GET_CODE (PATTERN (insn)) == COND_EXEC)
4404 cond = COND_EXEC_TEST (PATTERN (insn));
4406 /* Non-constant calls clobber memory. */
4407 if (! CONST_CALL_P (insn))
4409 free_EXPR_LIST_list (&pbi->mem_set_list);
4410 pbi->mem_set_list_len = 0;
4413 /* There may be extra registers to be clobbered. */
4414 for (note = CALL_INSN_FUNCTION_USAGE (insn);
4416 note = XEXP (note, 1))
4417 if (GET_CODE (XEXP (note, 0)) == CLOBBER)
4418 mark_set_1 (pbi, CLOBBER, XEXP (XEXP (note, 0), 0),
4419 cond, insn, pbi->flags);
4421 /* Calls change all call-used and global registers. */
4422 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
4423 if (call_used_regs[i] && ! global_regs[i]
4426 /* We do not want REG_UNUSED notes for these registers. */
4427 mark_set_1 (pbi, CLOBBER, gen_rtx_REG (reg_raw_mode[i], i),
4429 pbi->flags & ~(PROP_DEATH_NOTES | PROP_REG_INFO));
4433 /* If an insn doesn't use CC0, it becomes dead since we assume
4434 that every insn clobbers it. So show it dead here;
4435 mark_used_regs will set it live if it is referenced. */
4440 mark_used_regs (pbi, PATTERN (insn), NULL_RTX, insn);
4442 /* Sometimes we may have inserted something before INSN (such as a move)
4443 when we make an auto-inc. So ensure we will scan those insns. */
4445 prev = PREV_INSN (insn);
4448 if (! insn_is_dead && GET_CODE (insn) == CALL_INSN)
4454 if (GET_CODE (PATTERN (insn)) == COND_EXEC)
4455 cond = COND_EXEC_TEST (PATTERN (insn));
4457 /* Calls use their arguments. */
4458 for (note = CALL_INSN_FUNCTION_USAGE (insn);
4460 note = XEXP (note, 1))
4461 if (GET_CODE (XEXP (note, 0)) == USE)
4462 mark_used_regs (pbi, XEXP (XEXP (note, 0), 0),
4465 /* The stack ptr is used (honorarily) by a CALL insn. */
4466 SET_REGNO_REG_SET (pbi->reg_live, STACK_POINTER_REGNUM);
4468 /* Calls may also reference any of the global registers,
4469 so they are made live. */
4470 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
4472 mark_used_reg (pbi, gen_rtx_REG (reg_raw_mode[i], i),
4477 /* On final pass, update counts of how many insns in which each reg
4479 if (flags & PROP_REG_INFO)
4480 EXECUTE_IF_SET_IN_REG_SET (pbi->reg_live, 0, i,
4481 { REG_LIVE_LENGTH (i)++; });
4486 /* Initialize a propagate_block_info struct for public consumption.
4487 Note that the structure itself is opaque to this file, but that
4488 the user can use the regsets provided here. */
4490 struct propagate_block_info *
4491 init_propagate_block_info (bb, live, local_set, cond_local_set, flags)
4493 regset live, local_set, cond_local_set;
4496 struct propagate_block_info *pbi = xmalloc (sizeof (*pbi));
4499 pbi->reg_live = live;
4500 pbi->mem_set_list = NULL_RTX;
4501 pbi->mem_set_list_len = 0;
4502 pbi->local_set = local_set;
4503 pbi->cond_local_set = cond_local_set;
4507 if (flags & (PROP_LOG_LINKS | PROP_AUTOINC))
4508 pbi->reg_next_use = (rtx *) xcalloc (max_reg_num (), sizeof (rtx));
4510 pbi->reg_next_use = NULL;
4512 pbi->new_set = BITMAP_XMALLOC ();
4514 #ifdef HAVE_conditional_execution
4515 pbi->reg_cond_dead = splay_tree_new (splay_tree_compare_ints, NULL,
4516 free_reg_cond_life_info);
4517 pbi->reg_cond_reg = BITMAP_XMALLOC ();
4519 /* If this block ends in a conditional branch, for each register live
4520 from one side of the branch and not the other, record the register
4521 as conditionally dead. */
4522 if (GET_CODE (bb->end) == JUMP_INSN
4523 && any_condjump_p (bb->end))
4525 regset_head diff_head;
4526 regset diff = INITIALIZE_REG_SET (diff_head);
4527 basic_block bb_true, bb_false;
4528 rtx cond_true, cond_false, set_src;
4531 /* Identify the successor blocks. */
4532 bb_true = bb->succ->dest;
4533 if (bb->succ->succ_next != NULL)
4535 bb_false = bb->succ->succ_next->dest;
4537 if (bb->succ->flags & EDGE_FALLTHRU)
4539 basic_block t = bb_false;
4543 else if (! (bb->succ->succ_next->flags & EDGE_FALLTHRU))
4548 /* This can happen with a conditional jump to the next insn. */
4549 if (JUMP_LABEL (bb->end) != bb_true->head)
4552 /* Simplest way to do nothing. */
4556 /* Extract the condition from the branch. */
4557 set_src = SET_SRC (pc_set (bb->end));
4558 cond_true = XEXP (set_src, 0);
4559 cond_false = gen_rtx_fmt_ee (reverse_condition (GET_CODE (cond_true)),
4560 GET_MODE (cond_true), XEXP (cond_true, 0),
4561 XEXP (cond_true, 1));
4562 if (GET_CODE (XEXP (set_src, 1)) == PC)
4565 cond_false = cond_true;
4569 /* Compute which register lead different lives in the successors. */
4570 if (bitmap_operation (diff, bb_true->global_live_at_start,
4571 bb_false->global_live_at_start, BITMAP_XOR))
4573 rtx reg = XEXP (cond_true, 0);
4575 if (GET_CODE (reg) == SUBREG)
4576 reg = SUBREG_REG (reg);
4578 if (GET_CODE (reg) != REG)
4581 SET_REGNO_REG_SET (pbi->reg_cond_reg, REGNO (reg));
4583 /* For each such register, mark it conditionally dead. */
4584 EXECUTE_IF_SET_IN_REG_SET
4587 struct reg_cond_life_info *rcli;
4590 rcli = (struct reg_cond_life_info *) xmalloc (sizeof (*rcli));
4592 if (REGNO_REG_SET_P (bb_true->global_live_at_start, i))
4596 rcli->condition = cond;
4597 rcli->stores = const0_rtx;
4598 rcli->orig_condition = cond;
4600 splay_tree_insert (pbi->reg_cond_dead, i,
4601 (splay_tree_value) rcli);
4605 FREE_REG_SET (diff);
4609 /* If this block has no successors, any stores to the frame that aren't
4610 used later in the block are dead. So make a pass over the block
4611 recording any such that are made and show them dead at the end. We do
4612 a very conservative and simple job here. */
4614 && ! (TREE_CODE (TREE_TYPE (current_function_decl)) == FUNCTION_TYPE
4615 && (TYPE_RETURNS_STACK_DEPRESSED
4616 (TREE_TYPE (current_function_decl))))
4617 && (flags & PROP_SCAN_DEAD_CODE)
4618 && (bb->succ == NULL
4619 || (bb->succ->succ_next == NULL
4620 && bb->succ->dest == EXIT_BLOCK_PTR
4621 && ! current_function_calls_eh_return)))
4624 for (insn = bb->end; insn != bb->head; insn = PREV_INSN (insn))
4625 if (GET_CODE (insn) == INSN
4626 && (set = single_set (insn))
4627 && GET_CODE (SET_DEST (set)) == MEM)
4629 rtx mem = SET_DEST (set);
4630 rtx canon_mem = canon_rtx (mem);
4632 /* This optimization is performed by faking a store to the
4633 memory at the end of the block. This doesn't work for
4634 unchanging memories because multiple stores to unchanging
4635 memory is illegal and alias analysis doesn't consider it. */
4636 if (RTX_UNCHANGING_P (canon_mem))
4639 if (XEXP (canon_mem, 0) == frame_pointer_rtx
4640 || (GET_CODE (XEXP (canon_mem, 0)) == PLUS
4641 && XEXP (XEXP (canon_mem, 0), 0) == frame_pointer_rtx
4642 && GET_CODE (XEXP (XEXP (canon_mem, 0), 1)) == CONST_INT))
4645 /* Store a copy of mem, otherwise the address may be scrogged
4646 by find_auto_inc. This matters because insn_dead_p uses
4647 an rtx_equal_p check to determine if two addresses are
4648 the same. This works before find_auto_inc, but fails
4649 after find_auto_inc, causing discrepencies between the
4650 set of live registers calculated during the
4651 calculate_global_regs_live phase and what actually exists
4652 after flow completes, leading to aborts. */
4653 if (flags & PROP_AUTOINC)
4654 mem = shallow_copy_rtx (mem);
4656 pbi->mem_set_list = alloc_EXPR_LIST (0, mem, pbi->mem_set_list);
4657 if (++pbi->mem_set_list_len >= MAX_MEM_SET_LIST_LEN)
4666 /* Release a propagate_block_info struct. */
4669 free_propagate_block_info (pbi)
4670 struct propagate_block_info *pbi;
4672 free_EXPR_LIST_list (&pbi->mem_set_list);
4674 BITMAP_XFREE (pbi->new_set);
4676 #ifdef HAVE_conditional_execution
4677 splay_tree_delete (pbi->reg_cond_dead);
4678 BITMAP_XFREE (pbi->reg_cond_reg);
4681 if (pbi->reg_next_use)
4682 free (pbi->reg_next_use);
4687 /* Compute the registers live at the beginning of a basic block BB from
4688 those live at the end.
4690 When called, REG_LIVE contains those live at the end. On return, it
4691 contains those live at the beginning.
4693 LOCAL_SET, if non-null, will be set with all registers killed
4694 unconditionally by this basic block.
4695 Likewise, COND_LOCAL_SET, if non-null, will be set with all registers
4696 killed conditionally by this basic block. If there is any unconditional
4697 set of a register, then the corresponding bit will be set in LOCAL_SET
4698 and cleared in COND_LOCAL_SET.
4699 It is valid for LOCAL_SET and COND_LOCAL_SET to be the same set. In this
4700 case, the resulting set will be equal to the union of the two sets that
4701 would otherwise be computed. */
4704 propagate_block (bb, live, local_set, cond_local_set, flags)
4708 regset cond_local_set;
4711 struct propagate_block_info *pbi;
4714 pbi = init_propagate_block_info (bb, live, local_set, cond_local_set, flags);
4716 if (flags & PROP_REG_INFO)
4720 /* Process the regs live at the end of the block.
4721 Mark them as not local to any one basic block. */
4722 EXECUTE_IF_SET_IN_REG_SET (live, 0, i,
4723 { REG_BASIC_BLOCK (i) = REG_BLOCK_GLOBAL; });
4726 /* Scan the block an insn at a time from end to beginning. */
4728 for (insn = bb->end;; insn = prev)
4730 /* If this is a call to `setjmp' et al, warn if any
4731 non-volatile datum is live. */
4732 if ((flags & PROP_REG_INFO)
4733 && GET_CODE (insn) == NOTE
4734 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_SETJMP)
4735 IOR_REG_SET (regs_live_at_setjmp, pbi->reg_live);
4737 prev = propagate_one_insn (pbi, insn);
4739 if (insn == bb->head)
4743 free_propagate_block_info (pbi);
4746 /* Return 1 if X (the body of an insn, or part of it) is just dead stores
4747 (SET expressions whose destinations are registers dead after the insn).
4748 NEEDED is the regset that says which regs are alive after the insn.
4750 Unless CALL_OK is non-zero, an insn is needed if it contains a CALL.
4752 If X is the entire body of an insn, NOTES contains the reg notes
4753 pertaining to the insn. */
4756 insn_dead_p (pbi, x, call_ok, notes)
4757 struct propagate_block_info *pbi;
4760 rtx notes ATTRIBUTE_UNUSED;
4762 enum rtx_code code = GET_CODE (x);
4765 /* If flow is invoked after reload, we must take existing AUTO_INC
4766 expresions into account. */
4767 if (reload_completed)
4769 for (; notes; notes = XEXP (notes, 1))
4771 if (REG_NOTE_KIND (notes) == REG_INC)
4773 int regno = REGNO (XEXP (notes, 0));
4775 /* Don't delete insns to set global regs. */
4776 if ((regno < FIRST_PSEUDO_REGISTER && global_regs[regno])
4777 || REGNO_REG_SET_P (pbi->reg_live, regno))
4784 /* If setting something that's a reg or part of one,
4785 see if that register's altered value will be live. */
4789 rtx r = SET_DEST (x);
4792 if (GET_CODE (r) == CC0)
4793 return ! pbi->cc0_live;
4796 /* A SET that is a subroutine call cannot be dead. */
4797 if (GET_CODE (SET_SRC (x)) == CALL)
4803 /* Don't eliminate loads from volatile memory or volatile asms. */
4804 else if (volatile_refs_p (SET_SRC (x)))
4807 if (GET_CODE (r) == MEM)
4811 if (MEM_VOLATILE_P (r))
4814 /* Walk the set of memory locations we are currently tracking
4815 and see if one is an identical match to this memory location.
4816 If so, this memory write is dead (remember, we're walking
4817 backwards from the end of the block to the start). Since
4818 rtx_equal_p does not check the alias set or flags, we also
4819 must have the potential for them to conflict (anti_dependence). */
4820 for (temp = pbi->mem_set_list; temp != 0; temp = XEXP (temp, 1))
4821 if (anti_dependence (r, XEXP (temp, 0)))
4823 rtx mem = XEXP (temp, 0);
4825 if (rtx_equal_p (mem, r))
4828 /* Check if memory reference matches an auto increment. Only
4829 post increment/decrement or modify are valid. */
4830 if (GET_MODE (mem) == GET_MODE (r)
4831 && (GET_CODE (XEXP (mem, 0)) == POST_DEC
4832 || GET_CODE (XEXP (mem, 0)) == POST_INC
4833 || GET_CODE (XEXP (mem, 0)) == POST_MODIFY)
4834 && GET_MODE (XEXP (mem, 0)) == GET_MODE (r)
4835 && rtx_equal_p (XEXP (XEXP (mem, 0), 0), XEXP (r, 0)))
4842 while (GET_CODE (r) == SUBREG
4843 || GET_CODE (r) == STRICT_LOW_PART
4844 || GET_CODE (r) == ZERO_EXTRACT)
4847 if (GET_CODE (r) == REG)
4849 int regno = REGNO (r);
4852 if (REGNO_REG_SET_P (pbi->reg_live, regno))
4855 /* If this is a hard register, verify that subsequent
4856 words are not needed. */
4857 if (regno < FIRST_PSEUDO_REGISTER)
4859 int n = HARD_REGNO_NREGS (regno, GET_MODE (r));
4862 if (REGNO_REG_SET_P (pbi->reg_live, regno+n))
4866 /* Don't delete insns to set global regs. */
4867 if (regno < FIRST_PSEUDO_REGISTER && global_regs[regno])
4870 /* Make sure insns to set the stack pointer aren't deleted. */
4871 if (regno == STACK_POINTER_REGNUM)
4874 /* ??? These bits might be redundant with the force live bits
4875 in calculate_global_regs_live. We would delete from
4876 sequential sets; whether this actually affects real code
4877 for anything but the stack pointer I don't know. */
4878 /* Make sure insns to set the frame pointer aren't deleted. */
4879 if (regno == FRAME_POINTER_REGNUM
4880 && (! reload_completed || frame_pointer_needed))
4882 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
4883 if (regno == HARD_FRAME_POINTER_REGNUM
4884 && (! reload_completed || frame_pointer_needed))
4888 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
4889 /* Make sure insns to set arg pointer are never deleted
4890 (if the arg pointer isn't fixed, there will be a USE
4891 for it, so we can treat it normally). */
4892 if (regno == ARG_POINTER_REGNUM && fixed_regs[regno])
4896 /* Otherwise, the set is dead. */
4902 /* If performing several activities, insn is dead if each activity
4903 is individually dead. Also, CLOBBERs and USEs can be ignored; a
4904 CLOBBER or USE that's inside a PARALLEL doesn't make the insn
4906 else if (code == PARALLEL)
4908 int i = XVECLEN (x, 0);
4910 for (i--; i >= 0; i--)
4911 if (GET_CODE (XVECEXP (x, 0, i)) != CLOBBER
4912 && GET_CODE (XVECEXP (x, 0, i)) != USE
4913 && ! insn_dead_p (pbi, XVECEXP (x, 0, i), call_ok, NULL_RTX))
4919 /* A CLOBBER of a pseudo-register that is dead serves no purpose. That
4920 is not necessarily true for hard registers. */
4921 else if (code == CLOBBER && GET_CODE (XEXP (x, 0)) == REG
4922 && REGNO (XEXP (x, 0)) >= FIRST_PSEUDO_REGISTER
4923 && ! REGNO_REG_SET_P (pbi->reg_live, REGNO (XEXP (x, 0))))
4926 /* We do not check other CLOBBER or USE here. An insn consisting of just
4927 a CLOBBER or just a USE should not be deleted. */
4931 /* If INSN is the last insn in a libcall, and assuming INSN is dead,
4932 return 1 if the entire library call is dead.
4933 This is true if INSN copies a register (hard or pseudo)
4934 and if the hard return reg of the call insn is dead.
4935 (The caller should have tested the destination of the SET inside
4936 INSN already for death.)
4938 If this insn doesn't just copy a register, then we don't
4939 have an ordinary libcall. In that case, cse could not have
4940 managed to substitute the source for the dest later on,
4941 so we can assume the libcall is dead.
4943 PBI is the block info giving pseudoregs live before this insn.
4944 NOTE is the REG_RETVAL note of the insn. */
4947 libcall_dead_p (pbi, note, insn)
4948 struct propagate_block_info *pbi;
4952 rtx x = single_set (insn);
4956 register rtx r = SET_SRC (x);
4957 if (GET_CODE (r) == REG)
4959 rtx call = XEXP (note, 0);
4963 /* Find the call insn. */
4964 while (call != insn && GET_CODE (call) != CALL_INSN)
4965 call = NEXT_INSN (call);
4967 /* If there is none, do nothing special,
4968 since ordinary death handling can understand these insns. */
4972 /* See if the hard reg holding the value is dead.
4973 If this is a PARALLEL, find the call within it. */
4974 call_pat = PATTERN (call);
4975 if (GET_CODE (call_pat) == PARALLEL)
4977 for (i = XVECLEN (call_pat, 0) - 1; i >= 0; i--)
4978 if (GET_CODE (XVECEXP (call_pat, 0, i)) == SET
4979 && GET_CODE (SET_SRC (XVECEXP (call_pat, 0, i))) == CALL)
4982 /* This may be a library call that is returning a value
4983 via invisible pointer. Do nothing special, since
4984 ordinary death handling can understand these insns. */
4988 call_pat = XVECEXP (call_pat, 0, i);
4991 return insn_dead_p (pbi, call_pat, 1, REG_NOTES (call));
4997 /* Return 1 if register REGNO was used before it was set, i.e. if it is
4998 live at function entry. Don't count global register variables, variables
4999 in registers that can be used for function arg passing, or variables in
5000 fixed hard registers. */
5003 regno_uninitialized (regno)
5006 if (n_basic_blocks == 0
5007 || (regno < FIRST_PSEUDO_REGISTER
5008 && (global_regs[regno]
5009 || fixed_regs[regno]
5010 || FUNCTION_ARG_REGNO_P (regno))))
5013 return REGNO_REG_SET_P (BASIC_BLOCK (0)->global_live_at_start, regno);
5016 /* 1 if register REGNO was alive at a place where `setjmp' was called
5017 and was set more than once or is an argument.
5018 Such regs may be clobbered by `longjmp'. */
5021 regno_clobbered_at_setjmp (regno)
5024 if (n_basic_blocks == 0)
5027 return ((REG_N_SETS (regno) > 1
5028 || REGNO_REG_SET_P (BASIC_BLOCK (0)->global_live_at_start, regno))
5029 && REGNO_REG_SET_P (regs_live_at_setjmp, regno));
5032 /* INSN references memory, possibly using autoincrement addressing modes.
5033 Find any entries on the mem_set_list that need to be invalidated due
5034 to an address change. */
5037 invalidate_mems_from_autoinc (pbi, insn)
5038 struct propagate_block_info *pbi;
5041 rtx note = REG_NOTES (insn);
5042 for (note = REG_NOTES (insn); note; note = XEXP (note, 1))
5044 if (REG_NOTE_KIND (note) == REG_INC)
5046 rtx temp = pbi->mem_set_list;
5047 rtx prev = NULL_RTX;
5052 next = XEXP (temp, 1);
5053 if (reg_overlap_mentioned_p (XEXP (note, 0), XEXP (temp, 0)))
5055 /* Splice temp out of list. */
5057 XEXP (prev, 1) = next;
5059 pbi->mem_set_list = next;
5060 free_EXPR_LIST_node (temp);
5061 pbi->mem_set_list_len--;
5071 /* EXP is either a MEM or a REG. Remove any dependant entries
5072 from pbi->mem_set_list. */
5075 invalidate_mems_from_set (pbi, exp)
5076 struct propagate_block_info *pbi;
5079 rtx temp = pbi->mem_set_list;
5080 rtx prev = NULL_RTX;
5085 next = XEXP (temp, 1);
5086 if ((GET_CODE (exp) == MEM
5087 && output_dependence (XEXP (temp, 0), exp))
5088 || (GET_CODE (exp) == REG
5089 && reg_overlap_mentioned_p (exp, XEXP (temp, 0))))
5091 /* Splice this entry out of the list. */
5093 XEXP (prev, 1) = next;
5095 pbi->mem_set_list = next;
5096 free_EXPR_LIST_node (temp);
5097 pbi->mem_set_list_len--;
5105 /* Process the registers that are set within X. Their bits are set to
5106 1 in the regset DEAD, because they are dead prior to this insn.
5108 If INSN is nonzero, it is the insn being processed.
5110 FLAGS is the set of operations to perform. */
5113 mark_set_regs (pbi, x, insn)
5114 struct propagate_block_info *pbi;
5117 rtx cond = NULL_RTX;
5122 for (link = REG_NOTES (insn); link; link = XEXP (link, 1))
5124 if (REG_NOTE_KIND (link) == REG_INC)
5125 mark_set_1 (pbi, SET, XEXP (link, 0),
5126 (GET_CODE (x) == COND_EXEC
5127 ? COND_EXEC_TEST (x) : NULL_RTX),
5131 switch (code = GET_CODE (x))
5135 mark_set_1 (pbi, code, SET_DEST (x), cond, insn, pbi->flags);
5139 cond = COND_EXEC_TEST (x);
5140 x = COND_EXEC_CODE (x);
5146 for (i = XVECLEN (x, 0) - 1; i >= 0; i--)
5148 rtx sub = XVECEXP (x, 0, i);
5149 switch (code = GET_CODE (sub))
5152 if (cond != NULL_RTX)
5155 cond = COND_EXEC_TEST (sub);
5156 sub = COND_EXEC_CODE (sub);
5157 if (GET_CODE (sub) != SET && GET_CODE (sub) != CLOBBER)
5163 mark_set_1 (pbi, code, SET_DEST (sub), cond, insn, pbi->flags);
5178 /* Process a single set, which appears in INSN. REG (which may not
5179 actually be a REG, it may also be a SUBREG, PARALLEL, etc.) is
5180 being set using the CODE (which may be SET, CLOBBER, or COND_EXEC).
5181 If the set is conditional (because it appear in a COND_EXEC), COND
5182 will be the condition. */
5185 mark_set_1 (pbi, code, reg, cond, insn, flags)
5186 struct propagate_block_info *pbi;
5188 rtx reg, cond, insn;
5191 int regno_first = -1, regno_last = -1;
5192 unsigned long not_dead = 0;
5195 /* Modifying just one hardware register of a multi-reg value or just a
5196 byte field of a register does not mean the value from before this insn
5197 is now dead. Of course, if it was dead after it's unused now. */
5199 switch (GET_CODE (reg))
5202 /* Some targets place small structures in registers for return values of
5203 functions. We have to detect this case specially here to get correct
5204 flow information. */
5205 for (i = XVECLEN (reg, 0) - 1; i >= 0; i--)
5206 if (XEXP (XVECEXP (reg, 0, i), 0) != 0)
5207 mark_set_1 (pbi, code, XEXP (XVECEXP (reg, 0, i), 0), cond, insn,
5213 case STRICT_LOW_PART:
5214 /* ??? Assumes STRICT_LOW_PART not used on multi-word registers. */
5216 reg = XEXP (reg, 0);
5217 while (GET_CODE (reg) == SUBREG
5218 || GET_CODE (reg) == ZERO_EXTRACT
5219 || GET_CODE (reg) == SIGN_EXTRACT
5220 || GET_CODE (reg) == STRICT_LOW_PART);
5221 if (GET_CODE (reg) == MEM)
5223 not_dead = (unsigned long) REGNO_REG_SET_P (pbi->reg_live, REGNO (reg));
5227 regno_last = regno_first = REGNO (reg);
5228 if (regno_first < FIRST_PSEUDO_REGISTER)
5229 regno_last += HARD_REGNO_NREGS (regno_first, GET_MODE (reg)) - 1;
5233 if (GET_CODE (SUBREG_REG (reg)) == REG)
5235 enum machine_mode outer_mode = GET_MODE (reg);
5236 enum machine_mode inner_mode = GET_MODE (SUBREG_REG (reg));
5238 /* Identify the range of registers affected. This is moderately
5239 tricky for hard registers. See alter_subreg. */
5241 regno_last = regno_first = REGNO (SUBREG_REG (reg));
5242 if (regno_first < FIRST_PSEUDO_REGISTER)
5244 regno_first += subreg_regno_offset (regno_first, inner_mode,
5247 regno_last = (regno_first
5248 + HARD_REGNO_NREGS (regno_first, outer_mode) - 1);
5250 /* Since we've just adjusted the register number ranges, make
5251 sure REG matches. Otherwise some_was_live will be clear
5252 when it shouldn't have been, and we'll create incorrect
5253 REG_UNUSED notes. */
5254 reg = gen_rtx_REG (outer_mode, regno_first);
5258 /* If the number of words in the subreg is less than the number
5259 of words in the full register, we have a well-defined partial
5260 set. Otherwise the high bits are undefined.
5262 This is only really applicable to pseudos, since we just took
5263 care of multi-word hard registers. */
5264 if (((GET_MODE_SIZE (outer_mode)
5265 + UNITS_PER_WORD - 1) / UNITS_PER_WORD)
5266 < ((GET_MODE_SIZE (inner_mode)
5267 + UNITS_PER_WORD - 1) / UNITS_PER_WORD))
5268 not_dead = (unsigned long) REGNO_REG_SET_P (pbi->reg_live,
5271 reg = SUBREG_REG (reg);
5275 reg = SUBREG_REG (reg);
5282 /* If this set is a MEM, then it kills any aliased writes.
5283 If this set is a REG, then it kills any MEMs which use the reg. */
5284 if (optimize && (flags & PROP_SCAN_DEAD_CODE))
5286 if (GET_CODE (reg) == MEM || GET_CODE (reg) == REG)
5287 invalidate_mems_from_set (pbi, reg);
5289 /* If the memory reference had embedded side effects (autoincrement
5290 address modes. Then we may need to kill some entries on the
5292 if (insn && GET_CODE (reg) == MEM)
5293 invalidate_mems_from_autoinc (pbi, insn);
5295 if (pbi->mem_set_list_len < MAX_MEM_SET_LIST_LEN
5296 && GET_CODE (reg) == MEM && ! side_effects_p (reg)
5297 /* ??? With more effort we could track conditional memory life. */
5299 /* We do not know the size of a BLKmode store, so we do not track
5300 them for redundant store elimination. */
5301 && GET_MODE (reg) != BLKmode
5302 /* There are no REG_INC notes for SP, so we can't assume we'll see
5303 everything that invalidates it. To be safe, don't eliminate any
5304 stores though SP; none of them should be redundant anyway. */
5305 && ! reg_mentioned_p (stack_pointer_rtx, reg))
5308 /* Store a copy of mem, otherwise the address may be
5309 scrogged by find_auto_inc. */
5310 if (flags & PROP_AUTOINC)
5311 reg = shallow_copy_rtx (reg);
5313 pbi->mem_set_list = alloc_EXPR_LIST (0, reg, pbi->mem_set_list);
5314 pbi->mem_set_list_len++;
5318 if (GET_CODE (reg) == REG
5319 && ! (regno_first == FRAME_POINTER_REGNUM
5320 && (! reload_completed || frame_pointer_needed))
5321 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
5322 && ! (regno_first == HARD_FRAME_POINTER_REGNUM
5323 && (! reload_completed || frame_pointer_needed))
5325 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
5326 && ! (regno_first == ARG_POINTER_REGNUM && fixed_regs[regno_first])
5330 int some_was_live = 0, some_was_dead = 0;
5332 for (i = regno_first; i <= regno_last; ++i)
5334 int needed_regno = REGNO_REG_SET_P (pbi->reg_live, i);
5337 /* Order of the set operation matters here since both
5338 sets may be the same. */
5339 CLEAR_REGNO_REG_SET (pbi->cond_local_set, i);
5340 if (cond != NULL_RTX
5341 && ! REGNO_REG_SET_P (pbi->local_set, i))
5342 SET_REGNO_REG_SET (pbi->cond_local_set, i);
5344 SET_REGNO_REG_SET (pbi->local_set, i);
5346 if (code != CLOBBER)
5347 SET_REGNO_REG_SET (pbi->new_set, i);
5349 some_was_live |= needed_regno;
5350 some_was_dead |= ! needed_regno;
5353 #ifdef HAVE_conditional_execution
5354 /* Consider conditional death in deciding that the register needs
5356 if (some_was_live && ! not_dead
5357 /* The stack pointer is never dead. Well, not strictly true,
5358 but it's very difficult to tell from here. Hopefully
5359 combine_stack_adjustments will fix up the most egregious
5361 && regno_first != STACK_POINTER_REGNUM)
5363 for (i = regno_first; i <= regno_last; ++i)
5364 if (! mark_regno_cond_dead (pbi, i, cond))
5365 not_dead |= ((unsigned long) 1) << (i - regno_first);
5369 /* Additional data to record if this is the final pass. */
5370 if (flags & (PROP_LOG_LINKS | PROP_REG_INFO
5371 | PROP_DEATH_NOTES | PROP_AUTOINC))
5374 register int blocknum = pbi->bb->index;
5377 if (flags & (PROP_LOG_LINKS | PROP_AUTOINC))
5379 y = pbi->reg_next_use[regno_first];
5381 /* The next use is no longer next, since a store intervenes. */
5382 for (i = regno_first; i <= regno_last; ++i)
5383 pbi->reg_next_use[i] = 0;
5386 if (flags & PROP_REG_INFO)
5388 for (i = regno_first; i <= regno_last; ++i)
5390 /* Count (weighted) references, stores, etc. This counts a
5391 register twice if it is modified, but that is correct. */
5392 REG_N_SETS (i) += 1;
5393 REG_N_REFS (i) += 1;
5394 REG_FREQ (i) += (optimize_size || !pbi->bb->frequency
5395 ? 1 : pbi->bb->frequency);
5397 /* The insns where a reg is live are normally counted
5398 elsewhere, but we want the count to include the insn
5399 where the reg is set, and the normal counting mechanism
5400 would not count it. */
5401 REG_LIVE_LENGTH (i) += 1;
5404 /* If this is a hard reg, record this function uses the reg. */
5405 if (regno_first < FIRST_PSEUDO_REGISTER)
5407 for (i = regno_first; i <= regno_last; i++)
5408 regs_ever_live[i] = 1;
5412 /* Keep track of which basic blocks each reg appears in. */
5413 if (REG_BASIC_BLOCK (regno_first) == REG_BLOCK_UNKNOWN)
5414 REG_BASIC_BLOCK (regno_first) = blocknum;
5415 else if (REG_BASIC_BLOCK (regno_first) != blocknum)
5416 REG_BASIC_BLOCK (regno_first) = REG_BLOCK_GLOBAL;
5420 if (! some_was_dead)
5422 if (flags & PROP_LOG_LINKS)
5424 /* Make a logical link from the next following insn
5425 that uses this register, back to this insn.
5426 The following insns have already been processed.
5428 We don't build a LOG_LINK for hard registers containing
5429 in ASM_OPERANDs. If these registers get replaced,
5430 we might wind up changing the semantics of the insn,
5431 even if reload can make what appear to be valid
5432 assignments later. */
5433 if (y && (BLOCK_NUM (y) == blocknum)
5434 && (regno_first >= FIRST_PSEUDO_REGISTER
5435 || asm_noperands (PATTERN (y)) < 0))
5436 LOG_LINKS (y) = alloc_INSN_LIST (insn, LOG_LINKS (y));
5441 else if (! some_was_live)
5443 if (flags & PROP_REG_INFO)
5444 REG_N_DEATHS (regno_first) += 1;
5446 if (flags & PROP_DEATH_NOTES)
5448 /* Note that dead stores have already been deleted
5449 when possible. If we get here, we have found a
5450 dead store that cannot be eliminated (because the
5451 same insn does something useful). Indicate this
5452 by marking the reg being set as dying here. */
5454 = alloc_EXPR_LIST (REG_UNUSED, reg, REG_NOTES (insn));
5459 if (flags & PROP_DEATH_NOTES)
5461 /* This is a case where we have a multi-word hard register
5462 and some, but not all, of the words of the register are
5463 needed in subsequent insns. Write REG_UNUSED notes
5464 for those parts that were not needed. This case should
5467 for (i = regno_first; i <= regno_last; ++i)
5468 if (! REGNO_REG_SET_P (pbi->reg_live, i))
5470 = alloc_EXPR_LIST (REG_UNUSED,
5471 gen_rtx_REG (reg_raw_mode[i], i),
5477 /* Mark the register as being dead. */
5479 /* The stack pointer is never dead. Well, not strictly true,
5480 but it's very difficult to tell from here. Hopefully
5481 combine_stack_adjustments will fix up the most egregious
5483 && regno_first != STACK_POINTER_REGNUM)
5485 for (i = regno_first; i <= regno_last; ++i)
5486 if (!(not_dead & (((unsigned long) 1) << (i - regno_first))))
5487 CLEAR_REGNO_REG_SET (pbi->reg_live, i);
5490 else if (GET_CODE (reg) == REG)
5492 if (flags & (PROP_LOG_LINKS | PROP_AUTOINC))
5493 pbi->reg_next_use[regno_first] = 0;
5496 /* If this is the last pass and this is a SCRATCH, show it will be dying
5497 here and count it. */
5498 else if (GET_CODE (reg) == SCRATCH)
5500 if (flags & PROP_DEATH_NOTES)
5502 = alloc_EXPR_LIST (REG_UNUSED, reg, REG_NOTES (insn));
5506 #ifdef HAVE_conditional_execution
5507 /* Mark REGNO conditionally dead.
5508 Return true if the register is now unconditionally dead. */
5511 mark_regno_cond_dead (pbi, regno, cond)
5512 struct propagate_block_info *pbi;
5516 /* If this is a store to a predicate register, the value of the
5517 predicate is changing, we don't know that the predicate as seen
5518 before is the same as that seen after. Flush all dependent
5519 conditions from reg_cond_dead. This will make all such
5520 conditionally live registers unconditionally live. */
5521 if (REGNO_REG_SET_P (pbi->reg_cond_reg, regno))
5522 flush_reg_cond_reg (pbi, regno);
5524 /* If this is an unconditional store, remove any conditional
5525 life that may have existed. */
5526 if (cond == NULL_RTX)
5527 splay_tree_remove (pbi->reg_cond_dead, regno);
5530 splay_tree_node node;
5531 struct reg_cond_life_info *rcli;
5534 /* Otherwise this is a conditional set. Record that fact.
5535 It may have been conditionally used, or there may be a
5536 subsequent set with a complimentary condition. */
5538 node = splay_tree_lookup (pbi->reg_cond_dead, regno);
5541 /* The register was unconditionally live previously.
5542 Record the current condition as the condition under
5543 which it is dead. */
5544 rcli = (struct reg_cond_life_info *) xmalloc (sizeof (*rcli));
5545 rcli->condition = cond;
5546 rcli->stores = cond;
5547 rcli->orig_condition = const0_rtx;
5548 splay_tree_insert (pbi->reg_cond_dead, regno,
5549 (splay_tree_value) rcli);
5551 SET_REGNO_REG_SET (pbi->reg_cond_reg, REGNO (XEXP (cond, 0)));
5553 /* Not unconditionaly dead. */
5558 /* The register was conditionally live previously.
5559 Add the new condition to the old. */
5560 rcli = (struct reg_cond_life_info *) node->value;
5561 ncond = rcli->condition;
5562 ncond = ior_reg_cond (ncond, cond, 1);
5563 if (rcli->stores == const0_rtx)
5564 rcli->stores = cond;
5565 else if (rcli->stores != const1_rtx)
5566 rcli->stores = ior_reg_cond (rcli->stores, cond, 1);
5568 /* If the register is now unconditionally dead, remove the entry
5569 in the splay_tree. A register is unconditionally dead if the
5570 dead condition ncond is true. A register is also unconditionally
5571 dead if the sum of all conditional stores is an unconditional
5572 store (stores is true), and the dead condition is identically the
5573 same as the original dead condition initialized at the end of
5574 the block. This is a pointer compare, not an rtx_equal_p
5576 if (ncond == const1_rtx
5577 || (ncond == rcli->orig_condition && rcli->stores == const1_rtx))
5578 splay_tree_remove (pbi->reg_cond_dead, regno);
5581 rcli->condition = ncond;
5583 SET_REGNO_REG_SET (pbi->reg_cond_reg, REGNO (XEXP (cond, 0)));
5585 /* Not unconditionaly dead. */
5594 /* Called from splay_tree_delete for pbi->reg_cond_life. */
5597 free_reg_cond_life_info (value)
5598 splay_tree_value value;
5600 struct reg_cond_life_info *rcli = (struct reg_cond_life_info *) value;
5604 /* Helper function for flush_reg_cond_reg. */
5607 flush_reg_cond_reg_1 (node, data)
5608 splay_tree_node node;
5611 struct reg_cond_life_info *rcli;
5612 int *xdata = (int *) data;
5613 unsigned int regno = xdata[0];
5615 /* Don't need to search if last flushed value was farther on in
5616 the in-order traversal. */
5617 if (xdata[1] >= (int) node->key)
5620 /* Splice out portions of the expression that refer to regno. */
5621 rcli = (struct reg_cond_life_info *) node->value;
5622 rcli->condition = elim_reg_cond (rcli->condition, regno);
5623 if (rcli->stores != const0_rtx && rcli->stores != const1_rtx)
5624 rcli->stores = elim_reg_cond (rcli->stores, regno);
5626 /* If the entire condition is now false, signal the node to be removed. */
5627 if (rcli->condition == const0_rtx)
5629 xdata[1] = node->key;
5632 else if (rcli->condition == const1_rtx)
5638 /* Flush all (sub) expressions referring to REGNO from REG_COND_LIVE. */
5641 flush_reg_cond_reg (pbi, regno)
5642 struct propagate_block_info *pbi;
5649 while (splay_tree_foreach (pbi->reg_cond_dead,
5650 flush_reg_cond_reg_1, pair) == -1)
5651 splay_tree_remove (pbi->reg_cond_dead, pair[1]);
5653 CLEAR_REGNO_REG_SET (pbi->reg_cond_reg, regno);
5656 /* Logical arithmetic on predicate conditions. IOR, NOT and AND.
5657 For ior/and, the ADD flag determines whether we want to add the new
5658 condition X to the old one unconditionally. If it is zero, we will
5659 only return a new expression if X allows us to simplify part of
5660 OLD, otherwise we return OLD unchanged to the caller.
5661 If ADD is nonzero, we will return a new condition in all cases. The
5662 toplevel caller of one of these functions should always pass 1 for
5666 ior_reg_cond (old, x, add)
5672 if (GET_RTX_CLASS (GET_CODE (old)) == '<')
5674 if (GET_RTX_CLASS (GET_CODE (x)) == '<'
5675 && REVERSE_CONDEXEC_PREDICATES_P (GET_CODE (x), GET_CODE (old))
5676 && REGNO (XEXP (x, 0)) == REGNO (XEXP (old, 0)))
5678 if (GET_CODE (x) == GET_CODE (old)
5679 && REGNO (XEXP (x, 0)) == REGNO (XEXP (old, 0)))
5683 return gen_rtx_IOR (0, old, x);
5686 switch (GET_CODE (old))
5689 op0 = ior_reg_cond (XEXP (old, 0), x, 0);
5690 op1 = ior_reg_cond (XEXP (old, 1), x, 0);
5691 if (op0 != XEXP (old, 0) || op1 != XEXP (old, 1))
5693 if (op0 == const0_rtx)
5695 if (op1 == const0_rtx)
5697 if (op0 == const1_rtx || op1 == const1_rtx)
5699 if (op0 == XEXP (old, 0))
5700 op0 = gen_rtx_IOR (0, op0, x);
5702 op1 = gen_rtx_IOR (0, op1, x);
5703 return gen_rtx_IOR (0, op0, op1);
5707 return gen_rtx_IOR (0, old, x);
5710 op0 = ior_reg_cond (XEXP (old, 0), x, 0);
5711 op1 = ior_reg_cond (XEXP (old, 1), x, 0);
5712 if (op0 != XEXP (old, 0) || op1 != XEXP (old, 1))
5714 if (op0 == const1_rtx)
5716 if (op1 == const1_rtx)
5718 if (op0 == const0_rtx || op1 == const0_rtx)
5720 if (op0 == XEXP (old, 0))
5721 op0 = gen_rtx_IOR (0, op0, x);
5723 op1 = gen_rtx_IOR (0, op1, x);
5724 return gen_rtx_AND (0, op0, op1);
5728 return gen_rtx_IOR (0, old, x);
5731 op0 = and_reg_cond (XEXP (old, 0), not_reg_cond (x), 0);
5732 if (op0 != XEXP (old, 0))
5733 return not_reg_cond (op0);
5736 return gen_rtx_IOR (0, old, x);
5747 enum rtx_code x_code;
5749 if (x == const0_rtx)
5751 else if (x == const1_rtx)
5753 x_code = GET_CODE (x);
5756 if (GET_RTX_CLASS (x_code) == '<'
5757 && GET_CODE (XEXP (x, 0)) == REG)
5759 if (XEXP (x, 1) != const0_rtx)
5762 return gen_rtx_fmt_ee (reverse_condition (x_code),
5763 VOIDmode, XEXP (x, 0), const0_rtx);
5765 return gen_rtx_NOT (0, x);
5769 and_reg_cond (old, x, add)
5775 if (GET_RTX_CLASS (GET_CODE (old)) == '<')
5777 if (GET_RTX_CLASS (GET_CODE (x)) == '<'
5778 && GET_CODE (x) == reverse_condition (GET_CODE (old))
5779 && REGNO (XEXP (x, 0)) == REGNO (XEXP (old, 0)))
5781 if (GET_CODE (x) == GET_CODE (old)
5782 && REGNO (XEXP (x, 0)) == REGNO (XEXP (old, 0)))
5786 return gen_rtx_AND (0, old, x);
5789 switch (GET_CODE (old))
5792 op0 = and_reg_cond (XEXP (old, 0), x, 0);
5793 op1 = and_reg_cond (XEXP (old, 1), x, 0);
5794 if (op0 != XEXP (old, 0) || op1 != XEXP (old, 1))
5796 if (op0 == const0_rtx)
5798 if (op1 == const0_rtx)
5800 if (op0 == const1_rtx || op1 == const1_rtx)
5802 if (op0 == XEXP (old, 0))
5803 op0 = gen_rtx_AND (0, op0, x);
5805 op1 = gen_rtx_AND (0, op1, x);
5806 return gen_rtx_IOR (0, op0, op1);
5810 return gen_rtx_AND (0, old, x);
5813 op0 = and_reg_cond (XEXP (old, 0), x, 0);
5814 op1 = and_reg_cond (XEXP (old, 1), x, 0);
5815 if (op0 != XEXP (old, 0) || op1 != XEXP (old, 1))
5817 if (op0 == const1_rtx)
5819 if (op1 == const1_rtx)
5821 if (op0 == const0_rtx || op1 == const0_rtx)
5823 if (op0 == XEXP (old, 0))
5824 op0 = gen_rtx_AND (0, op0, x);
5826 op1 = gen_rtx_AND (0, op1, x);
5827 return gen_rtx_AND (0, op0, op1);
5832 /* If X is identical to one of the existing terms of the AND,
5833 then just return what we already have. */
5834 /* ??? There really should be some sort of recursive check here in
5835 case there are nested ANDs. */
5836 if ((GET_CODE (XEXP (old, 0)) == GET_CODE (x)
5837 && REGNO (XEXP (XEXP (old, 0), 0)) == REGNO (XEXP (x, 0)))
5838 || (GET_CODE (XEXP (old, 1)) == GET_CODE (x)
5839 && REGNO (XEXP (XEXP (old, 1), 0)) == REGNO (XEXP (x, 0))))
5842 return gen_rtx_AND (0, old, x);
5845 op0 = ior_reg_cond (XEXP (old, 0), not_reg_cond (x), 0);
5846 if (op0 != XEXP (old, 0))
5847 return not_reg_cond (op0);
5850 return gen_rtx_AND (0, old, x);
5857 /* Given a condition X, remove references to reg REGNO and return the
5858 new condition. The removal will be done so that all conditions
5859 involving REGNO are considered to evaluate to false. This function
5860 is used when the value of REGNO changes. */
5863 elim_reg_cond (x, regno)
5869 if (GET_RTX_CLASS (GET_CODE (x)) == '<')
5871 if (REGNO (XEXP (x, 0)) == regno)
5876 switch (GET_CODE (x))
5879 op0 = elim_reg_cond (XEXP (x, 0), regno);
5880 op1 = elim_reg_cond (XEXP (x, 1), regno);
5881 if (op0 == const0_rtx || op1 == const0_rtx)
5883 if (op0 == const1_rtx)
5885 if (op1 == const1_rtx)
5887 if (op0 == XEXP (x, 0) && op1 == XEXP (x, 1))
5889 return gen_rtx_AND (0, op0, op1);
5892 op0 = elim_reg_cond (XEXP (x, 0), regno);
5893 op1 = elim_reg_cond (XEXP (x, 1), regno);
5894 if (op0 == const1_rtx || op1 == const1_rtx)
5896 if (op0 == const0_rtx)
5898 if (op1 == const0_rtx)
5900 if (op0 == XEXP (x, 0) && op1 == XEXP (x, 1))
5902 return gen_rtx_IOR (0, op0, op1);
5905 op0 = elim_reg_cond (XEXP (x, 0), regno);
5906 if (op0 == const0_rtx)
5908 if (op0 == const1_rtx)
5910 if (op0 != XEXP (x, 0))
5911 return not_reg_cond (op0);
5918 #endif /* HAVE_conditional_execution */
5922 /* Try to substitute the auto-inc expression INC as the address inside
5923 MEM which occurs in INSN. Currently, the address of MEM is an expression
5924 involving INCR_REG, and INCR is the next use of INCR_REG; it is an insn
5925 that has a single set whose source is a PLUS of INCR_REG and something
5929 attempt_auto_inc (pbi, inc, insn, mem, incr, incr_reg)
5930 struct propagate_block_info *pbi;
5931 rtx inc, insn, mem, incr, incr_reg;
5933 int regno = REGNO (incr_reg);
5934 rtx set = single_set (incr);
5935 rtx q = SET_DEST (set);
5936 rtx y = SET_SRC (set);
5937 int opnum = XEXP (y, 0) == incr_reg ? 0 : 1;
5939 /* Make sure this reg appears only once in this insn. */
5940 if (count_occurrences (PATTERN (insn), incr_reg, 1) != 1)
5943 if (dead_or_set_p (incr, incr_reg)
5944 /* Mustn't autoinc an eliminable register. */
5945 && (regno >= FIRST_PSEUDO_REGISTER
5946 || ! TEST_HARD_REG_BIT (elim_reg_set, regno)))
5948 /* This is the simple case. Try to make the auto-inc. If
5949 we can't, we are done. Otherwise, we will do any
5950 needed updates below. */
5951 if (! validate_change (insn, &XEXP (mem, 0), inc, 0))
5954 else if (GET_CODE (q) == REG
5955 /* PREV_INSN used here to check the semi-open interval
5957 && ! reg_used_between_p (q, PREV_INSN (insn), incr)
5958 /* We must also check for sets of q as q may be
5959 a call clobbered hard register and there may
5960 be a call between PREV_INSN (insn) and incr. */
5961 && ! reg_set_between_p (q, PREV_INSN (insn), incr))
5963 /* We have *p followed sometime later by q = p+size.
5964 Both p and q must be live afterward,
5965 and q is not used between INSN and its assignment.
5966 Change it to q = p, ...*q..., q = q+size.
5967 Then fall into the usual case. */
5971 emit_move_insn (q, incr_reg);
5972 insns = get_insns ();
5975 if (basic_block_for_insn)
5976 for (temp = insns; temp; temp = NEXT_INSN (temp))
5977 set_block_for_insn (temp, pbi->bb);
5979 /* If we can't make the auto-inc, or can't make the
5980 replacement into Y, exit. There's no point in making
5981 the change below if we can't do the auto-inc and doing
5982 so is not correct in the pre-inc case. */
5985 validate_change (insn, &XEXP (mem, 0), inc, 1);
5986 validate_change (incr, &XEXP (y, opnum), q, 1);
5987 if (! apply_change_group ())
5990 /* We now know we'll be doing this change, so emit the
5991 new insn(s) and do the updates. */
5992 emit_insns_before (insns, insn);
5994 if (pbi->bb->head == insn)
5995 pbi->bb->head = insns;
5997 /* INCR will become a NOTE and INSN won't contain a
5998 use of INCR_REG. If a use of INCR_REG was just placed in
5999 the insn before INSN, make that the next use.
6000 Otherwise, invalidate it. */
6001 if (GET_CODE (PREV_INSN (insn)) == INSN
6002 && GET_CODE (PATTERN (PREV_INSN (insn))) == SET
6003 && SET_SRC (PATTERN (PREV_INSN (insn))) == incr_reg)
6004 pbi->reg_next_use[regno] = PREV_INSN (insn);
6006 pbi->reg_next_use[regno] = 0;
6011 /* REGNO is now used in INCR which is below INSN, but
6012 it previously wasn't live here. If we don't mark
6013 it as live, we'll put a REG_DEAD note for it
6014 on this insn, which is incorrect. */
6015 SET_REGNO_REG_SET (pbi->reg_live, regno);
6017 /* If there are any calls between INSN and INCR, show
6018 that REGNO now crosses them. */
6019 for (temp = insn; temp != incr; temp = NEXT_INSN (temp))
6020 if (GET_CODE (temp) == CALL_INSN)
6021 REG_N_CALLS_CROSSED (regno)++;
6026 /* If we haven't returned, it means we were able to make the
6027 auto-inc, so update the status. First, record that this insn
6028 has an implicit side effect. */
6030 REG_NOTES (insn) = alloc_EXPR_LIST (REG_INC, incr_reg, REG_NOTES (insn));
6032 /* Modify the old increment-insn to simply copy
6033 the already-incremented value of our register. */
6034 if (! validate_change (incr, &SET_SRC (set), incr_reg, 0))
6037 /* If that makes it a no-op (copying the register into itself) delete
6038 it so it won't appear to be a "use" and a "set" of this
6040 if (REGNO (SET_DEST (set)) == REGNO (incr_reg))
6042 /* If the original source was dead, it's dead now. */
6045 while ((note = find_reg_note (incr, REG_DEAD, NULL_RTX)) != NULL_RTX)
6047 remove_note (incr, note);
6048 if (XEXP (note, 0) != incr_reg)
6049 CLEAR_REGNO_REG_SET (pbi->reg_live, REGNO (XEXP (note, 0)));
6052 PUT_CODE (incr, NOTE);
6053 NOTE_LINE_NUMBER (incr) = NOTE_INSN_DELETED;
6054 NOTE_SOURCE_FILE (incr) = 0;
6057 if (regno >= FIRST_PSEUDO_REGISTER)
6059 /* Count an extra reference to the reg. When a reg is
6060 incremented, spilling it is worse, so we want to make
6061 that less likely. */
6062 REG_FREQ (regno) += (optimize_size || !pbi->bb->frequency
6063 ? 1 : pbi->bb->frequency);
6065 /* Count the increment as a setting of the register,
6066 even though it isn't a SET in rtl. */
6067 REG_N_SETS (regno)++;
6071 /* X is a MEM found in INSN. See if we can convert it into an auto-increment
6075 find_auto_inc (pbi, x, insn)
6076 struct propagate_block_info *pbi;
6080 rtx addr = XEXP (x, 0);
6081 HOST_WIDE_INT offset = 0;
6082 rtx set, y, incr, inc_val;
6084 int size = GET_MODE_SIZE (GET_MODE (x));
6086 if (GET_CODE (insn) == JUMP_INSN)
6089 /* Here we detect use of an index register which might be good for
6090 postincrement, postdecrement, preincrement, or predecrement. */
6092 if (GET_CODE (addr) == PLUS && GET_CODE (XEXP (addr, 1)) == CONST_INT)
6093 offset = INTVAL (XEXP (addr, 1)), addr = XEXP (addr, 0);
6095 if (GET_CODE (addr) != REG)
6098 regno = REGNO (addr);
6100 /* Is the next use an increment that might make auto-increment? */
6101 incr = pbi->reg_next_use[regno];
6102 if (incr == 0 || BLOCK_NUM (incr) != BLOCK_NUM (insn))
6104 set = single_set (incr);
6105 if (set == 0 || GET_CODE (set) != SET)
6109 if (GET_CODE (y) != PLUS)
6112 if (REG_P (XEXP (y, 0)) && REGNO (XEXP (y, 0)) == REGNO (addr))
6113 inc_val = XEXP (y, 1);
6114 else if (REG_P (XEXP (y, 1)) && REGNO (XEXP (y, 1)) == REGNO (addr))
6115 inc_val = XEXP (y, 0);
6119 if (GET_CODE (inc_val) == CONST_INT)
6121 if (HAVE_POST_INCREMENT
6122 && (INTVAL (inc_val) == size && offset == 0))
6123 attempt_auto_inc (pbi, gen_rtx_POST_INC (Pmode, addr), insn, x,
6125 else if (HAVE_POST_DECREMENT
6126 && (INTVAL (inc_val) == -size && offset == 0))
6127 attempt_auto_inc (pbi, gen_rtx_POST_DEC (Pmode, addr), insn, x,
6129 else if (HAVE_PRE_INCREMENT
6130 && (INTVAL (inc_val) == size && offset == size))
6131 attempt_auto_inc (pbi, gen_rtx_PRE_INC (Pmode, addr), insn, x,
6133 else if (HAVE_PRE_DECREMENT
6134 && (INTVAL (inc_val) == -size && offset == -size))
6135 attempt_auto_inc (pbi, gen_rtx_PRE_DEC (Pmode, addr), insn, x,
6137 else if (HAVE_POST_MODIFY_DISP && offset == 0)
6138 attempt_auto_inc (pbi, gen_rtx_POST_MODIFY (Pmode, addr,
6139 gen_rtx_PLUS (Pmode,
6142 insn, x, incr, addr);
6144 else if (GET_CODE (inc_val) == REG
6145 && ! reg_set_between_p (inc_val, PREV_INSN (insn),
6149 if (HAVE_POST_MODIFY_REG && offset == 0)
6150 attempt_auto_inc (pbi, gen_rtx_POST_MODIFY (Pmode, addr,
6151 gen_rtx_PLUS (Pmode,
6154 insn, x, incr, addr);
6158 #endif /* AUTO_INC_DEC */
6161 mark_used_reg (pbi, reg, cond, insn)
6162 struct propagate_block_info *pbi;
6164 rtx cond ATTRIBUTE_UNUSED;
6167 unsigned int regno_first, regno_last, i;
6168 int some_was_live, some_was_dead, some_not_set;
6170 regno_last = regno_first = REGNO (reg);
6171 if (regno_first < FIRST_PSEUDO_REGISTER)
6172 regno_last += HARD_REGNO_NREGS (regno_first, GET_MODE (reg)) - 1;
6174 /* Find out if any of this register is live after this instruction. */
6175 some_was_live = some_was_dead = 0;
6176 for (i = regno_first; i <= regno_last; ++i)
6178 int needed_regno = REGNO_REG_SET_P (pbi->reg_live, i);
6179 some_was_live |= needed_regno;
6180 some_was_dead |= ! needed_regno;
6183 /* Find out if any of the register was set this insn. */
6185 for (i = regno_first; i <= regno_last; ++i)
6186 some_not_set |= ! REGNO_REG_SET_P (pbi->new_set, i);
6188 if (pbi->flags & (PROP_LOG_LINKS | PROP_AUTOINC))
6190 /* Record where each reg is used, so when the reg is set we know
6191 the next insn that uses it. */
6192 pbi->reg_next_use[regno_first] = insn;
6195 if (pbi->flags & PROP_REG_INFO)
6197 if (regno_first < FIRST_PSEUDO_REGISTER)
6199 /* If this is a register we are going to try to eliminate,
6200 don't mark it live here. If we are successful in
6201 eliminating it, it need not be live unless it is used for
6202 pseudos, in which case it will have been set live when it
6203 was allocated to the pseudos. If the register will not
6204 be eliminated, reload will set it live at that point.
6206 Otherwise, record that this function uses this register. */
6207 /* ??? The PPC backend tries to "eliminate" on the pic
6208 register to itself. This should be fixed. In the mean
6209 time, hack around it. */
6211 if (! (TEST_HARD_REG_BIT (elim_reg_set, regno_first)
6212 && (regno_first == FRAME_POINTER_REGNUM
6213 || regno_first == ARG_POINTER_REGNUM)))
6214 for (i = regno_first; i <= regno_last; ++i)
6215 regs_ever_live[i] = 1;
6219 /* Keep track of which basic block each reg appears in. */
6221 register int blocknum = pbi->bb->index;
6222 if (REG_BASIC_BLOCK (regno_first) == REG_BLOCK_UNKNOWN)
6223 REG_BASIC_BLOCK (regno_first) = blocknum;
6224 else if (REG_BASIC_BLOCK (regno_first) != blocknum)
6225 REG_BASIC_BLOCK (regno_first) = REG_BLOCK_GLOBAL;
6227 /* Count (weighted) number of uses of each reg. */
6228 REG_FREQ (regno_first)
6229 += (optimize_size || !pbi->bb->frequency ? 1 : pbi->bb->frequency);
6230 REG_N_REFS (regno_first)++;
6234 /* Record and count the insns in which a reg dies. If it is used in
6235 this insn and was dead below the insn then it dies in this insn.
6236 If it was set in this insn, we do not make a REG_DEAD note;
6237 likewise if we already made such a note. */
6238 if ((pbi->flags & (PROP_DEATH_NOTES | PROP_REG_INFO))
6242 /* Check for the case where the register dying partially
6243 overlaps the register set by this insn. */
6244 if (regno_first != regno_last)
6245 for (i = regno_first; i <= regno_last; ++i)
6246 some_was_live |= REGNO_REG_SET_P (pbi->new_set, i);
6248 /* If none of the words in X is needed, make a REG_DEAD note.
6249 Otherwise, we must make partial REG_DEAD notes. */
6250 if (! some_was_live)
6252 if ((pbi->flags & PROP_DEATH_NOTES)
6253 && ! find_regno_note (insn, REG_DEAD, regno_first))
6255 = alloc_EXPR_LIST (REG_DEAD, reg, REG_NOTES (insn));
6257 if (pbi->flags & PROP_REG_INFO)
6258 REG_N_DEATHS (regno_first)++;
6262 /* Don't make a REG_DEAD note for a part of a register
6263 that is set in the insn. */
6264 for (i = regno_first; i <= regno_last; ++i)
6265 if (! REGNO_REG_SET_P (pbi->reg_live, i)
6266 && ! dead_or_set_regno_p (insn, i))
6268 = alloc_EXPR_LIST (REG_DEAD,
6269 gen_rtx_REG (reg_raw_mode[i], i),
6274 /* Mark the register as being live. */
6275 for (i = regno_first; i <= regno_last; ++i)
6277 SET_REGNO_REG_SET (pbi->reg_live, i);
6279 #ifdef HAVE_conditional_execution
6280 /* If this is a conditional use, record that fact. If it is later
6281 conditionally set, we'll know to kill the register. */
6282 if (cond != NULL_RTX)
6284 splay_tree_node node;
6285 struct reg_cond_life_info *rcli;
6290 node = splay_tree_lookup (pbi->reg_cond_dead, i);
6293 /* The register was unconditionally live previously.
6294 No need to do anything. */
6298 /* The register was conditionally live previously.
6299 Subtract the new life cond from the old death cond. */
6300 rcli = (struct reg_cond_life_info *) node->value;
6301 ncond = rcli->condition;
6302 ncond = and_reg_cond (ncond, not_reg_cond (cond), 1);
6304 /* If the register is now unconditionally live,
6305 remove the entry in the splay_tree. */
6306 if (ncond == const0_rtx)
6307 splay_tree_remove (pbi->reg_cond_dead, i);
6310 rcli->condition = ncond;
6311 SET_REGNO_REG_SET (pbi->reg_cond_reg,
6312 REGNO (XEXP (cond, 0)));
6318 /* The register was not previously live at all. Record
6319 the condition under which it is still dead. */
6320 rcli = (struct reg_cond_life_info *) xmalloc (sizeof (*rcli));
6321 rcli->condition = not_reg_cond (cond);
6322 rcli->stores = const0_rtx;
6323 rcli->orig_condition = const0_rtx;
6324 splay_tree_insert (pbi->reg_cond_dead, i,
6325 (splay_tree_value) rcli);
6327 SET_REGNO_REG_SET (pbi->reg_cond_reg, REGNO (XEXP (cond, 0)));
6330 else if (some_was_live)
6332 /* The register may have been conditionally live previously, but
6333 is now unconditionally live. Remove it from the conditionally
6334 dead list, so that a conditional set won't cause us to think
6336 splay_tree_remove (pbi->reg_cond_dead, i);
6342 /* Scan expression X and store a 1-bit in NEW_LIVE for each reg it uses.
6343 This is done assuming the registers needed from X are those that
6344 have 1-bits in PBI->REG_LIVE.
6346 INSN is the containing instruction. If INSN is dead, this function
6350 mark_used_regs (pbi, x, cond, insn)
6351 struct propagate_block_info *pbi;
6354 register RTX_CODE code;
6356 int flags = pbi->flags;
6359 code = GET_CODE (x);
6379 /* If we are clobbering a MEM, mark any registers inside the address
6381 if (GET_CODE (XEXP (x, 0)) == MEM)
6382 mark_used_regs (pbi, XEXP (XEXP (x, 0), 0), cond, insn);
6386 /* Don't bother watching stores to mems if this is not the
6387 final pass. We'll not be deleting dead stores this round. */
6388 if (optimize && (flags & PROP_SCAN_DEAD_CODE))
6390 /* Invalidate the data for the last MEM stored, but only if MEM is
6391 something that can be stored into. */
6392 if (GET_CODE (XEXP (x, 0)) == SYMBOL_REF
6393 && CONSTANT_POOL_ADDRESS_P (XEXP (x, 0)))
6394 /* Needn't clear the memory set list. */
6398 rtx temp = pbi->mem_set_list;
6399 rtx prev = NULL_RTX;
6404 next = XEXP (temp, 1);
6405 if (anti_dependence (XEXP (temp, 0), x))
6407 /* Splice temp out of the list. */
6409 XEXP (prev, 1) = next;
6411 pbi->mem_set_list = next;
6412 free_EXPR_LIST_node (temp);
6413 pbi->mem_set_list_len--;
6421 /* If the memory reference had embedded side effects (autoincrement
6422 address modes. Then we may need to kill some entries on the
6425 invalidate_mems_from_autoinc (pbi, insn);
6429 if (flags & PROP_AUTOINC)
6430 find_auto_inc (pbi, x, insn);
6435 #ifdef CLASS_CANNOT_CHANGE_MODE
6436 if (GET_CODE (SUBREG_REG (x)) == REG
6437 && REGNO (SUBREG_REG (x)) >= FIRST_PSEUDO_REGISTER
6438 && CLASS_CANNOT_CHANGE_MODE_P (GET_MODE (x),
6439 GET_MODE (SUBREG_REG (x))))
6440 REG_CHANGES_MODE (REGNO (SUBREG_REG (x))) = 1;
6443 /* While we're here, optimize this case. */
6445 if (GET_CODE (x) != REG)
6450 /* See a register other than being set => mark it as needed. */
6451 mark_used_reg (pbi, x, cond, insn);
6456 register rtx testreg = SET_DEST (x);
6459 /* If storing into MEM, don't show it as being used. But do
6460 show the address as being used. */
6461 if (GET_CODE (testreg) == MEM)
6464 if (flags & PROP_AUTOINC)
6465 find_auto_inc (pbi, testreg, insn);
6467 mark_used_regs (pbi, XEXP (testreg, 0), cond, insn);
6468 mark_used_regs (pbi, SET_SRC (x), cond, insn);
6472 /* Storing in STRICT_LOW_PART is like storing in a reg
6473 in that this SET might be dead, so ignore it in TESTREG.
6474 but in some other ways it is like using the reg.
6476 Storing in a SUBREG or a bit field is like storing the entire
6477 register in that if the register's value is not used
6478 then this SET is not needed. */
6479 while (GET_CODE (testreg) == STRICT_LOW_PART
6480 || GET_CODE (testreg) == ZERO_EXTRACT
6481 || GET_CODE (testreg) == SIGN_EXTRACT
6482 || GET_CODE (testreg) == SUBREG)
6484 #ifdef CLASS_CANNOT_CHANGE_MODE
6485 if (GET_CODE (testreg) == SUBREG
6486 && GET_CODE (SUBREG_REG (testreg)) == REG
6487 && REGNO (SUBREG_REG (testreg)) >= FIRST_PSEUDO_REGISTER
6488 && CLASS_CANNOT_CHANGE_MODE_P (GET_MODE (SUBREG_REG (testreg)),
6489 GET_MODE (testreg)))
6490 REG_CHANGES_MODE (REGNO (SUBREG_REG (testreg))) = 1;
6493 /* Modifying a single register in an alternate mode
6494 does not use any of the old value. But these other
6495 ways of storing in a register do use the old value. */
6496 if (GET_CODE (testreg) == SUBREG
6497 && !(REG_SIZE (SUBREG_REG (testreg)) > REG_SIZE (testreg)))
6502 testreg = XEXP (testreg, 0);
6505 /* If this is a store into a register or group of registers,
6506 recursively scan the value being stored. */
6508 if ((GET_CODE (testreg) == PARALLEL
6509 && GET_MODE (testreg) == BLKmode)
6510 || (GET_CODE (testreg) == REG
6511 && (regno = REGNO (testreg),
6512 ! (regno == FRAME_POINTER_REGNUM
6513 && (! reload_completed || frame_pointer_needed)))
6514 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
6515 && ! (regno == HARD_FRAME_POINTER_REGNUM
6516 && (! reload_completed || frame_pointer_needed))
6518 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
6519 && ! (regno == ARG_POINTER_REGNUM && fixed_regs[regno])
6524 mark_used_regs (pbi, SET_DEST (x), cond, insn);
6525 mark_used_regs (pbi, SET_SRC (x), cond, insn);
6532 case UNSPEC_VOLATILE:
6536 /* Traditional and volatile asm instructions must be considered to use
6537 and clobber all hard registers, all pseudo-registers and all of
6538 memory. So must TRAP_IF and UNSPEC_VOLATILE operations.
6540 Consider for instance a volatile asm that changes the fpu rounding
6541 mode. An insn should not be moved across this even if it only uses
6542 pseudo-regs because it might give an incorrectly rounded result.
6544 ?!? Unfortunately, marking all hard registers as live causes massive
6545 problems for the register allocator and marking all pseudos as live
6546 creates mountains of uninitialized variable warnings.
6548 So for now, just clear the memory set list and mark any regs
6549 we can find in ASM_OPERANDS as used. */
6550 if (code != ASM_OPERANDS || MEM_VOLATILE_P (x))
6552 free_EXPR_LIST_list (&pbi->mem_set_list);
6553 pbi->mem_set_list_len = 0;
6556 /* For all ASM_OPERANDS, we must traverse the vector of input operands.
6557 We can not just fall through here since then we would be confused
6558 by the ASM_INPUT rtx inside ASM_OPERANDS, which do not indicate
6559 traditional asms unlike their normal usage. */
6560 if (code == ASM_OPERANDS)
6564 for (j = 0; j < ASM_OPERANDS_INPUT_LENGTH (x); j++)
6565 mark_used_regs (pbi, ASM_OPERANDS_INPUT (x, j), cond, insn);
6571 if (cond != NULL_RTX)
6574 mark_used_regs (pbi, COND_EXEC_TEST (x), NULL_RTX, insn);
6576 cond = COND_EXEC_TEST (x);
6577 x = COND_EXEC_CODE (x);
6581 /* We _do_not_ want to scan operands of phi nodes. Operands of
6582 a phi function are evaluated only when control reaches this
6583 block along a particular edge. Therefore, regs that appear
6584 as arguments to phi should not be added to the global live at
6592 /* Recursively scan the operands of this expression. */
6595 register const char *fmt = GET_RTX_FORMAT (code);
6598 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
6602 /* Tail recursive case: save a function call level. */
6608 mark_used_regs (pbi, XEXP (x, i), cond, insn);
6610 else if (fmt[i] == 'E')
6613 for (j = 0; j < XVECLEN (x, i); j++)
6614 mark_used_regs (pbi, XVECEXP (x, i, j), cond, insn);
6623 try_pre_increment_1 (pbi, insn)
6624 struct propagate_block_info *pbi;
6627 /* Find the next use of this reg. If in same basic block,
6628 make it do pre-increment or pre-decrement if appropriate. */
6629 rtx x = single_set (insn);
6630 HOST_WIDE_INT amount = ((GET_CODE (SET_SRC (x)) == PLUS ? 1 : -1)
6631 * INTVAL (XEXP (SET_SRC (x), 1)));
6632 int regno = REGNO (SET_DEST (x));
6633 rtx y = pbi->reg_next_use[regno];
6635 && SET_DEST (x) != stack_pointer_rtx
6636 && BLOCK_NUM (y) == BLOCK_NUM (insn)
6637 /* Don't do this if the reg dies, or gets set in y; a standard addressing
6638 mode would be better. */
6639 && ! dead_or_set_p (y, SET_DEST (x))
6640 && try_pre_increment (y, SET_DEST (x), amount))
6642 /* We have found a suitable auto-increment and already changed
6643 insn Y to do it. So flush this increment instruction. */
6644 propagate_block_delete_insn (pbi->bb, insn);
6646 /* Count a reference to this reg for the increment insn we are
6647 deleting. When a reg is incremented, spilling it is worse,
6648 so we want to make that less likely. */
6649 if (regno >= FIRST_PSEUDO_REGISTER)
6651 REG_FREQ (regno) += (optimize_size || !pbi->bb->frequency
6652 ? 1 : pbi->bb->frequency);
6653 REG_N_SETS (regno)++;
6656 /* Flush any remembered memories depending on the value of
6657 the incremented register. */
6658 invalidate_mems_from_set (pbi, SET_DEST (x));
6665 /* Try to change INSN so that it does pre-increment or pre-decrement
6666 addressing on register REG in order to add AMOUNT to REG.
6667 AMOUNT is negative for pre-decrement.
6668 Returns 1 if the change could be made.
6669 This checks all about the validity of the result of modifying INSN. */
6672 try_pre_increment (insn, reg, amount)
6674 HOST_WIDE_INT amount;
6678 /* Nonzero if we can try to make a pre-increment or pre-decrement.
6679 For example, addl $4,r1; movl (r1),... can become movl +(r1),... */
6681 /* Nonzero if we can try to make a post-increment or post-decrement.
6682 For example, addl $4,r1; movl -4(r1),... can become movl (r1)+,...
6683 It is possible for both PRE_OK and POST_OK to be nonzero if the machine
6684 supports both pre-inc and post-inc, or both pre-dec and post-dec. */
6687 /* Nonzero if the opportunity actually requires post-inc or post-dec. */
6690 /* From the sign of increment, see which possibilities are conceivable
6691 on this target machine. */
6692 if (HAVE_PRE_INCREMENT && amount > 0)
6694 if (HAVE_POST_INCREMENT && amount > 0)
6697 if (HAVE_PRE_DECREMENT && amount < 0)
6699 if (HAVE_POST_DECREMENT && amount < 0)
6702 if (! (pre_ok || post_ok))
6705 /* It is not safe to add a side effect to a jump insn
6706 because if the incremented register is spilled and must be reloaded
6707 there would be no way to store the incremented value back in memory. */
6709 if (GET_CODE (insn) == JUMP_INSN)
6714 use = find_use_as_address (PATTERN (insn), reg, 0);
6715 if (post_ok && (use == 0 || use == (rtx) 1))
6717 use = find_use_as_address (PATTERN (insn), reg, -amount);
6721 if (use == 0 || use == (rtx) 1)
6724 if (GET_MODE_SIZE (GET_MODE (use)) != (amount > 0 ? amount : - amount))
6727 /* See if this combination of instruction and addressing mode exists. */
6728 if (! validate_change (insn, &XEXP (use, 0),
6729 gen_rtx_fmt_e (amount > 0
6730 ? (do_post ? POST_INC : PRE_INC)
6731 : (do_post ? POST_DEC : PRE_DEC),
6735 /* Record that this insn now has an implicit side effect on X. */
6736 REG_NOTES (insn) = alloc_EXPR_LIST (REG_INC, reg, REG_NOTES (insn));
6740 #endif /* AUTO_INC_DEC */
6742 /* Find the place in the rtx X where REG is used as a memory address.
6743 Return the MEM rtx that so uses it.
6744 If PLUSCONST is nonzero, search instead for a memory address equivalent to
6745 (plus REG (const_int PLUSCONST)).
6747 If such an address does not appear, return 0.
6748 If REG appears more than once, or is used other than in such an address,
6752 find_use_as_address (x, reg, plusconst)
6755 HOST_WIDE_INT plusconst;
6757 enum rtx_code code = GET_CODE (x);
6758 const char *fmt = GET_RTX_FORMAT (code);
6760 register rtx value = 0;
6763 if (code == MEM && XEXP (x, 0) == reg && plusconst == 0)
6766 if (code == MEM && GET_CODE (XEXP (x, 0)) == PLUS
6767 && XEXP (XEXP (x, 0), 0) == reg
6768 && GET_CODE (XEXP (XEXP (x, 0), 1)) == CONST_INT
6769 && INTVAL (XEXP (XEXP (x, 0), 1)) == plusconst)
6772 if (code == SIGN_EXTRACT || code == ZERO_EXTRACT)
6774 /* If REG occurs inside a MEM used in a bit-field reference,
6775 that is unacceptable. */
6776 if (find_use_as_address (XEXP (x, 0), reg, 0) != 0)
6777 return (rtx) (HOST_WIDE_INT) 1;
6781 return (rtx) (HOST_WIDE_INT) 1;
6783 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
6787 tem = find_use_as_address (XEXP (x, i), reg, plusconst);
6791 return (rtx) (HOST_WIDE_INT) 1;
6793 else if (fmt[i] == 'E')
6796 for (j = XVECLEN (x, i) - 1; j >= 0; j--)
6798 tem = find_use_as_address (XVECEXP (x, i, j), reg, plusconst);
6802 return (rtx) (HOST_WIDE_INT) 1;
6810 /* Write information about registers and basic blocks into FILE.
6811 This is part of making a debugging dump. */
6814 dump_regset (r, outf)
6821 fputs (" (nil)", outf);
6825 EXECUTE_IF_SET_IN_REG_SET (r, 0, i,
6827 fprintf (outf, " %d", i);
6828 if (i < FIRST_PSEUDO_REGISTER)
6829 fprintf (outf, " [%s]",
6834 /* Print a human-reaable representation of R on the standard error
6835 stream. This function is designed to be used from within the
6842 dump_regset (r, stderr);
6843 putc ('\n', stderr);
6847 dump_flow_info (file)
6851 static const char * const reg_class_names[] = REG_CLASS_NAMES;
6853 fprintf (file, "%d registers.\n", max_regno);
6854 for (i = FIRST_PSEUDO_REGISTER; i < max_regno; i++)
6857 enum reg_class class, altclass;
6858 fprintf (file, "\nRegister %d used %d times across %d insns",
6859 i, REG_N_REFS (i), REG_LIVE_LENGTH (i));
6860 if (REG_BASIC_BLOCK (i) >= 0)
6861 fprintf (file, " in block %d", REG_BASIC_BLOCK (i));
6863 fprintf (file, "; set %d time%s", REG_N_SETS (i),
6864 (REG_N_SETS (i) == 1) ? "" : "s");
6865 if (REG_USERVAR_P (regno_reg_rtx[i]))
6866 fprintf (file, "; user var");
6867 if (REG_N_DEATHS (i) != 1)
6868 fprintf (file, "; dies in %d places", REG_N_DEATHS (i));
6869 if (REG_N_CALLS_CROSSED (i) == 1)
6870 fprintf (file, "; crosses 1 call");
6871 else if (REG_N_CALLS_CROSSED (i))
6872 fprintf (file, "; crosses %d calls", REG_N_CALLS_CROSSED (i));
6873 if (PSEUDO_REGNO_BYTES (i) != UNITS_PER_WORD)
6874 fprintf (file, "; %d bytes", PSEUDO_REGNO_BYTES (i));
6875 class = reg_preferred_class (i);
6876 altclass = reg_alternate_class (i);
6877 if (class != GENERAL_REGS || altclass != ALL_REGS)
6879 if (altclass == ALL_REGS || class == ALL_REGS)
6880 fprintf (file, "; pref %s", reg_class_names[(int) class]);
6881 else if (altclass == NO_REGS)
6882 fprintf (file, "; %s or none", reg_class_names[(int) class]);
6884 fprintf (file, "; pref %s, else %s",
6885 reg_class_names[(int) class],
6886 reg_class_names[(int) altclass]);
6888 if (REG_POINTER (regno_reg_rtx[i]))
6889 fprintf (file, "; pointer");
6890 fprintf (file, ".\n");
6893 fprintf (file, "\n%d basic blocks, %d edges.\n", n_basic_blocks, n_edges);
6894 for (i = 0; i < n_basic_blocks; i++)
6896 register basic_block bb = BASIC_BLOCK (i);
6899 fprintf (file, "\nBasic block %d: first insn %d, last %d, loop_depth %d, count ",
6900 i, INSN_UID (bb->head), INSN_UID (bb->end), bb->loop_depth);
6901 fprintf (file, HOST_WIDEST_INT_PRINT_DEC, (HOST_WIDEST_INT) bb->count);
6902 fprintf (file, ", freq %i.\n", bb->frequency);
6904 fprintf (file, "Predecessors: ");
6905 for (e = bb->pred; e; e = e->pred_next)
6906 dump_edge_info (file, e, 0);
6908 fprintf (file, "\nSuccessors: ");
6909 for (e = bb->succ; e; e = e->succ_next)
6910 dump_edge_info (file, e, 1);
6912 fprintf (file, "\nRegisters live at start:");
6913 dump_regset (bb->global_live_at_start, file);
6915 fprintf (file, "\nRegisters live at end:");
6916 dump_regset (bb->global_live_at_end, file);
6927 dump_flow_info (stderr);
6931 dump_edge_info (file, e, do_succ)
6936 basic_block side = (do_succ ? e->dest : e->src);
6938 if (side == ENTRY_BLOCK_PTR)
6939 fputs (" ENTRY", file);
6940 else if (side == EXIT_BLOCK_PTR)
6941 fputs (" EXIT", file);
6943 fprintf (file, " %d", side->index);
6946 fprintf (file, " [%.1f%%] ", e->probability * 100.0 / REG_BR_PROB_BASE);
6950 fprintf (file, " count:");
6951 fprintf (file, HOST_WIDEST_INT_PRINT_DEC, (HOST_WIDEST_INT) e->count);
6956 static const char * const bitnames[] = {
6957 "fallthru", "crit", "ab", "abcall", "eh", "fake"
6960 int i, flags = e->flags;
6964 for (i = 0; flags; i++)
6965 if (flags & (1 << i))
6971 if (i < (int) ARRAY_SIZE (bitnames))
6972 fputs (bitnames[i], file);
6974 fprintf (file, "%d", i);
6981 /* Print out one basic block with live information at start and end. */
6992 fprintf (outf, ";; Basic block %d, loop depth %d, count ",
6993 bb->index, bb->loop_depth);
6994 fprintf (outf, HOST_WIDEST_INT_PRINT_DEC, (HOST_WIDEST_INT) bb->count);
6997 fputs (";; Predecessors: ", outf);
6998 for (e = bb->pred; e; e = e->pred_next)
6999 dump_edge_info (outf, e, 0);
7002 fputs (";; Registers live at start:", outf);
7003 dump_regset (bb->global_live_at_start, outf);
7006 for (insn = bb->head, last = NEXT_INSN (bb->end);
7008 insn = NEXT_INSN (insn))
7009 print_rtl_single (outf, insn);
7011 fputs (";; Registers live at end:", outf);
7012 dump_regset (bb->global_live_at_end, outf);
7015 fputs (";; Successors: ", outf);
7016 for (e = bb->succ; e; e = e->succ_next)
7017 dump_edge_info (outf, e, 1);
7025 dump_bb (bb, stderr);
7032 dump_bb (BASIC_BLOCK (n), stderr);
7035 /* Like print_rtl, but also print out live information for the start of each
7039 print_rtl_with_bb (outf, rtx_first)
7043 register rtx tmp_rtx;
7046 fprintf (outf, "(nil)\n");
7050 enum bb_state { NOT_IN_BB, IN_ONE_BB, IN_MULTIPLE_BB };
7051 int max_uid = get_max_uid ();
7052 basic_block *start = (basic_block *)
7053 xcalloc (max_uid, sizeof (basic_block));
7054 basic_block *end = (basic_block *)
7055 xcalloc (max_uid, sizeof (basic_block));
7056 enum bb_state *in_bb_p = (enum bb_state *)
7057 xcalloc (max_uid, sizeof (enum bb_state));
7059 for (i = n_basic_blocks - 1; i >= 0; i--)
7061 basic_block bb = BASIC_BLOCK (i);
7064 start[INSN_UID (bb->head)] = bb;
7065 end[INSN_UID (bb->end)] = bb;
7066 for (x = bb->head; x != NULL_RTX; x = NEXT_INSN (x))
7068 enum bb_state state = IN_MULTIPLE_BB;
7069 if (in_bb_p[INSN_UID (x)] == NOT_IN_BB)
7071 in_bb_p[INSN_UID (x)] = state;
7078 for (tmp_rtx = rtx_first; NULL != tmp_rtx; tmp_rtx = NEXT_INSN (tmp_rtx))
7083 if ((bb = start[INSN_UID (tmp_rtx)]) != NULL)
7085 fprintf (outf, ";; Start of basic block %d, registers live:",
7087 dump_regset (bb->global_live_at_start, outf);
7091 if (in_bb_p[INSN_UID (tmp_rtx)] == NOT_IN_BB
7092 && GET_CODE (tmp_rtx) != NOTE
7093 && GET_CODE (tmp_rtx) != BARRIER)
7094 fprintf (outf, ";; Insn is not within a basic block\n");
7095 else if (in_bb_p[INSN_UID (tmp_rtx)] == IN_MULTIPLE_BB)
7096 fprintf (outf, ";; Insn is in multiple basic blocks\n");
7098 did_output = print_rtl_single (outf, tmp_rtx);
7100 if ((bb = end[INSN_UID (tmp_rtx)]) != NULL)
7102 fprintf (outf, ";; End of basic block %d, registers live:\n",
7104 dump_regset (bb->global_live_at_end, outf);
7117 if (current_function_epilogue_delay_list != 0)
7119 fprintf (outf, "\n;; Insns in epilogue delay list:\n\n");
7120 for (tmp_rtx = current_function_epilogue_delay_list; tmp_rtx != 0;
7121 tmp_rtx = XEXP (tmp_rtx, 1))
7122 print_rtl_single (outf, XEXP (tmp_rtx, 0));
7126 /* Dump the rtl into the current debugging dump file, then abort. */
7129 print_rtl_and_abort_fcn (file, line, function)
7132 const char *function;
7136 print_rtl_with_bb (rtl_dump_file, get_insns ());
7137 fclose (rtl_dump_file);
7140 fancy_abort (file, line, function);
7143 /* Recompute register set/reference counts immediately prior to register
7146 This avoids problems with set/reference counts changing to/from values
7147 which have special meanings to the register allocators.
7149 Additionally, the reference counts are the primary component used by the
7150 register allocators to prioritize pseudos for allocation to hard regs.
7151 More accurate reference counts generally lead to better register allocation.
7153 F is the first insn to be scanned.
7155 LOOP_STEP denotes how much loop_depth should be incremented per
7156 loop nesting level in order to increase the ref count more for
7157 references in a loop.
7159 It might be worthwhile to update REG_LIVE_LENGTH, REG_BASIC_BLOCK and
7160 possibly other information which is used by the register allocators. */
7163 recompute_reg_usage (f, loop_step)
7164 rtx f ATTRIBUTE_UNUSED;
7165 int loop_step ATTRIBUTE_UNUSED;
7167 allocate_reg_life_data ();
7168 update_life_info (NULL, UPDATE_LIFE_LOCAL, PROP_REG_INFO);
7171 /* Optionally removes all the REG_DEAD and REG_UNUSED notes from a set of
7172 blocks. If BLOCKS is NULL, assume the universal set. Returns a count
7173 of the number of registers that died. */
7176 count_or_remove_death_notes (blocks, kill)
7182 for (i = n_basic_blocks - 1; i >= 0; --i)
7187 if (blocks && ! TEST_BIT (blocks, i))
7190 bb = BASIC_BLOCK (i);
7192 for (insn = bb->head;; insn = NEXT_INSN (insn))
7196 rtx *pprev = ®_NOTES (insn);
7201 switch (REG_NOTE_KIND (link))
7204 if (GET_CODE (XEXP (link, 0)) == REG)
7206 rtx reg = XEXP (link, 0);
7209 if (REGNO (reg) >= FIRST_PSEUDO_REGISTER)
7212 n = HARD_REGNO_NREGS (REGNO (reg), GET_MODE (reg));
7220 rtx next = XEXP (link, 1);
7221 free_EXPR_LIST_node (link);
7222 *pprev = link = next;
7228 pprev = &XEXP (link, 1);
7235 if (insn == bb->end)
7244 /* Update insns block within BB. */
7247 update_bb_for_insn (bb)
7252 if (! basic_block_for_insn)
7255 for (insn = bb->head; ; insn = NEXT_INSN (insn))
7257 set_block_for_insn (insn, bb);
7259 if (insn == bb->end)
7265 /* Record INSN's block as BB. */
7268 set_block_for_insn (insn, bb)
7272 size_t uid = INSN_UID (insn);
7273 if (uid >= basic_block_for_insn->num_elements)
7277 /* Add one-eighth the size so we don't keep calling xrealloc. */
7278 new_size = uid + (uid + 7) / 8;
7280 VARRAY_GROW (basic_block_for_insn, new_size);
7282 VARRAY_BB (basic_block_for_insn, uid) = bb;
7285 /* When a new insn has been inserted into an existing block, it will
7286 sometimes emit more than a single insn. This routine will set the
7287 block number for the specified insn, and look backwards in the insn
7288 chain to see if there are any other uninitialized insns immediately
7289 previous to this one, and set the block number for them too. */
7292 set_block_for_new_insns (insn, bb)
7296 set_block_for_insn (insn, bb);
7298 /* Scan the previous instructions setting the block number until we find
7299 an instruction that has the block number set, or we find a note
7301 for (insn = PREV_INSN (insn); insn != NULL_RTX; insn = PREV_INSN (insn))
7303 if (GET_CODE (insn) == NOTE)
7305 if (INSN_UID (insn) >= basic_block_for_insn->num_elements
7306 || BLOCK_FOR_INSN (insn) == 0)
7307 set_block_for_insn (insn, bb);
7313 /* Verify the CFG consistency. This function check some CFG invariants and
7314 aborts when something is wrong. Hope that this function will help to
7315 convert many optimization passes to preserve CFG consistent.
7317 Currently it does following checks:
7319 - test head/end pointers
7320 - overlapping of basic blocks
7321 - edge list corectness
7322 - headers of basic blocks (the NOTE_INSN_BASIC_BLOCK note)
7323 - tails of basic blocks (ensure that boundary is necesary)
7324 - scans body of the basic block for JUMP_INSN, CODE_LABEL
7325 and NOTE_INSN_BASIC_BLOCK
7326 - check that all insns are in the basic blocks
7327 (except the switch handling code, barriers and notes)
7328 - check that all returns are followed by barriers
7330 In future it can be extended check a lot of other stuff as well
7331 (reachability of basic blocks, life information, etc. etc.). */
7336 const int max_uid = get_max_uid ();
7337 const rtx rtx_first = get_insns ();
7338 rtx last_head = get_last_insn ();
7339 basic_block *bb_info;
7341 int i, last_bb_num_seen, num_bb_notes, err = 0;
7343 bb_info = (basic_block *) xcalloc (max_uid, sizeof (basic_block));
7345 for (i = n_basic_blocks - 1; i >= 0; i--)
7347 basic_block bb = BASIC_BLOCK (i);
7348 rtx head = bb->head;
7351 /* Verify the end of the basic block is in the INSN chain. */
7352 for (x = last_head; x != NULL_RTX; x = PREV_INSN (x))
7357 error ("End insn %d for block %d not found in the insn stream.",
7358 INSN_UID (end), bb->index);
7362 /* Work backwards from the end to the head of the basic block
7363 to verify the head is in the RTL chain. */
7364 for (; x != NULL_RTX; x = PREV_INSN (x))
7366 /* While walking over the insn chain, verify insns appear
7367 in only one basic block and initialize the BB_INFO array
7368 used by other passes. */
7369 if (bb_info[INSN_UID (x)] != NULL)
7371 error ("Insn %d is in multiple basic blocks (%d and %d)",
7372 INSN_UID (x), bb->index, bb_info[INSN_UID (x)]->index);
7375 bb_info[INSN_UID (x)] = bb;
7382 error ("Head insn %d for block %d not found in the insn stream.",
7383 INSN_UID (head), bb->index);
7390 /* Now check the basic blocks (boundaries etc.) */
7391 for (i = n_basic_blocks - 1; i >= 0; i--)
7393 basic_block bb = BASIC_BLOCK (i);
7394 /* Check corectness of edge lists */
7403 "verify_flow_info: Basic block %d succ edge is corrupted\n",
7405 fprintf (stderr, "Predecessor: ");
7406 dump_edge_info (stderr, e, 0);
7407 fprintf (stderr, "\nSuccessor: ");
7408 dump_edge_info (stderr, e, 1);
7412 if (e->dest != EXIT_BLOCK_PTR)
7414 edge e2 = e->dest->pred;
7415 while (e2 && e2 != e)
7419 error ("Basic block %i edge lists are corrupted", bb->index);
7431 error ("Basic block %d pred edge is corrupted", bb->index);
7432 fputs ("Predecessor: ", stderr);
7433 dump_edge_info (stderr, e, 0);
7434 fputs ("\nSuccessor: ", stderr);
7435 dump_edge_info (stderr, e, 1);
7436 fputc ('\n', stderr);
7439 if (e->src != ENTRY_BLOCK_PTR)
7441 edge e2 = e->src->succ;
7442 while (e2 && e2 != e)
7446 error ("Basic block %i edge lists are corrupted", bb->index);
7453 /* OK pointers are correct. Now check the header of basic
7454 block. It ought to contain optional CODE_LABEL followed
7455 by NOTE_BASIC_BLOCK. */
7457 if (GET_CODE (x) == CODE_LABEL)
7461 error ("NOTE_INSN_BASIC_BLOCK is missing for block %d",
7467 if (!NOTE_INSN_BASIC_BLOCK_P (x) || NOTE_BASIC_BLOCK (x) != bb)
7469 error ("NOTE_INSN_BASIC_BLOCK is missing for block %d\n",
7476 /* Do checks for empty blocks here */
7483 if (NOTE_INSN_BASIC_BLOCK_P (x))
7485 error ("NOTE_INSN_BASIC_BLOCK %d in the middle of basic block %d",
7486 INSN_UID (x), bb->index);
7493 if (GET_CODE (x) == JUMP_INSN
7494 || GET_CODE (x) == CODE_LABEL
7495 || GET_CODE (x) == BARRIER)
7497 error ("In basic block %d:", bb->index);
7498 fatal_insn ("Flow control insn inside a basic block", x);
7506 last_bb_num_seen = -1;
7511 if (NOTE_INSN_BASIC_BLOCK_P (x))
7513 basic_block bb = NOTE_BASIC_BLOCK (x);
7515 if (bb->index != last_bb_num_seen + 1)
7516 /* Basic blocks not numbered consecutively. */
7519 last_bb_num_seen = bb->index;
7522 if (!bb_info[INSN_UID (x)])
7524 switch (GET_CODE (x))
7531 /* An addr_vec is placed outside any block block. */
7533 && GET_CODE (NEXT_INSN (x)) == JUMP_INSN
7534 && (GET_CODE (PATTERN (NEXT_INSN (x))) == ADDR_DIFF_VEC
7535 || GET_CODE (PATTERN (NEXT_INSN (x))) == ADDR_VEC))
7540 /* But in any case, non-deletable labels can appear anywhere. */
7544 fatal_insn ("Insn outside basic block", x);
7549 && GET_CODE (x) == JUMP_INSN
7550 && returnjump_p (x) && ! condjump_p (x)
7551 && ! (NEXT_INSN (x) && GET_CODE (NEXT_INSN (x)) == BARRIER))
7552 fatal_insn ("Return not followed by barrier", x);
7557 if (num_bb_notes != n_basic_blocks)
7559 ("number of bb notes in insn chain (%d) != n_basic_blocks (%d)",
7560 num_bb_notes, n_basic_blocks);
7569 /* Functions to access an edge list with a vector representation.
7570 Enough data is kept such that given an index number, the
7571 pred and succ that edge represents can be determined, or
7572 given a pred and a succ, its index number can be returned.
7573 This allows algorithms which consume a lot of memory to
7574 represent the normally full matrix of edge (pred,succ) with a
7575 single indexed vector, edge (EDGE_INDEX (pred, succ)), with no
7576 wasted space in the client code due to sparse flow graphs. */
7578 /* This functions initializes the edge list. Basically the entire
7579 flowgraph is processed, and all edges are assigned a number,
7580 and the data structure is filled in. */
7585 struct edge_list *elist;
7591 block_count = n_basic_blocks + 2; /* Include the entry and exit blocks. */
7595 /* Determine the number of edges in the flow graph by counting successor
7596 edges on each basic block. */
7597 for (x = 0; x < n_basic_blocks; x++)
7599 basic_block bb = BASIC_BLOCK (x);
7601 for (e = bb->succ; e; e = e->succ_next)
7604 /* Don't forget successors of the entry block. */
7605 for (e = ENTRY_BLOCK_PTR->succ; e; e = e->succ_next)
7608 elist = (struct edge_list *) xmalloc (sizeof (struct edge_list));
7609 elist->num_blocks = block_count;
7610 elist->num_edges = num_edges;
7611 elist->index_to_edge = (edge *) xmalloc (sizeof (edge) * num_edges);
7615 /* Follow successors of the entry block, and register these edges. */
7616 for (e = ENTRY_BLOCK_PTR->succ; e; e = e->succ_next)
7618 elist->index_to_edge[num_edges] = e;
7622 for (x = 0; x < n_basic_blocks; x++)
7624 basic_block bb = BASIC_BLOCK (x);
7626 /* Follow all successors of blocks, and register these edges. */
7627 for (e = bb->succ; e; e = e->succ_next)
7629 elist->index_to_edge[num_edges] = e;
7636 /* This function free's memory associated with an edge list. */
7639 free_edge_list (elist)
7640 struct edge_list *elist;
7644 free (elist->index_to_edge);
7649 /* This function provides debug output showing an edge list. */
7652 print_edge_list (f, elist)
7654 struct edge_list *elist;
7657 fprintf (f, "Compressed edge list, %d BBs + entry & exit, and %d edges\n",
7658 elist->num_blocks - 2, elist->num_edges);
7660 for (x = 0; x < elist->num_edges; x++)
7662 fprintf (f, " %-4d - edge(", x);
7663 if (INDEX_EDGE_PRED_BB (elist, x) == ENTRY_BLOCK_PTR)
7664 fprintf (f, "entry,");
7666 fprintf (f, "%d,", INDEX_EDGE_PRED_BB (elist, x)->index);
7668 if (INDEX_EDGE_SUCC_BB (elist, x) == EXIT_BLOCK_PTR)
7669 fprintf (f, "exit)\n");
7671 fprintf (f, "%d)\n", INDEX_EDGE_SUCC_BB (elist, x)->index);
7675 /* This function provides an internal consistency check of an edge list,
7676 verifying that all edges are present, and that there are no
7680 verify_edge_list (f, elist)
7682 struct edge_list *elist;
7684 int x, pred, succ, index;
7687 for (x = 0; x < n_basic_blocks; x++)
7689 basic_block bb = BASIC_BLOCK (x);
7691 for (e = bb->succ; e; e = e->succ_next)
7693 pred = e->src->index;
7694 succ = e->dest->index;
7695 index = EDGE_INDEX (elist, e->src, e->dest);
7696 if (index == EDGE_INDEX_NO_EDGE)
7698 fprintf (f, "*p* No index for edge from %d to %d\n", pred, succ);
7701 if (INDEX_EDGE_PRED_BB (elist, index)->index != pred)
7702 fprintf (f, "*p* Pred for index %d should be %d not %d\n",
7703 index, pred, INDEX_EDGE_PRED_BB (elist, index)->index);
7704 if (INDEX_EDGE_SUCC_BB (elist, index)->index != succ)
7705 fprintf (f, "*p* Succ for index %d should be %d not %d\n",
7706 index, succ, INDEX_EDGE_SUCC_BB (elist, index)->index);
7709 for (e = ENTRY_BLOCK_PTR->succ; e; e = e->succ_next)
7711 pred = e->src->index;
7712 succ = e->dest->index;
7713 index = EDGE_INDEX (elist, e->src, e->dest);
7714 if (index == EDGE_INDEX_NO_EDGE)
7716 fprintf (f, "*p* No index for edge from %d to %d\n", pred, succ);
7719 if (INDEX_EDGE_PRED_BB (elist, index)->index != pred)
7720 fprintf (f, "*p* Pred for index %d should be %d not %d\n",
7721 index, pred, INDEX_EDGE_PRED_BB (elist, index)->index);
7722 if (INDEX_EDGE_SUCC_BB (elist, index)->index != succ)
7723 fprintf (f, "*p* Succ for index %d should be %d not %d\n",
7724 index, succ, INDEX_EDGE_SUCC_BB (elist, index)->index);
7726 /* We've verified that all the edges are in the list, no lets make sure
7727 there are no spurious edges in the list. */
7729 for (pred = 0; pred < n_basic_blocks; pred++)
7730 for (succ = 0; succ < n_basic_blocks; succ++)
7732 basic_block p = BASIC_BLOCK (pred);
7733 basic_block s = BASIC_BLOCK (succ);
7737 for (e = p->succ; e; e = e->succ_next)
7743 for (e = s->pred; e; e = e->pred_next)
7749 if (EDGE_INDEX (elist, BASIC_BLOCK (pred), BASIC_BLOCK (succ))
7750 == EDGE_INDEX_NO_EDGE && found_edge != 0)
7751 fprintf (f, "*** Edge (%d, %d) appears to not have an index\n",
7753 if (EDGE_INDEX (elist, BASIC_BLOCK (pred), BASIC_BLOCK (succ))
7754 != EDGE_INDEX_NO_EDGE && found_edge == 0)
7755 fprintf (f, "*** Edge (%d, %d) has index %d, but there is no edge\n",
7756 pred, succ, EDGE_INDEX (elist, BASIC_BLOCK (pred),
7757 BASIC_BLOCK (succ)));
7759 for (succ = 0; succ < n_basic_blocks; succ++)
7761 basic_block p = ENTRY_BLOCK_PTR;
7762 basic_block s = BASIC_BLOCK (succ);
7766 for (e = p->succ; e; e = e->succ_next)
7772 for (e = s->pred; e; e = e->pred_next)
7778 if (EDGE_INDEX (elist, ENTRY_BLOCK_PTR, BASIC_BLOCK (succ))
7779 == EDGE_INDEX_NO_EDGE && found_edge != 0)
7780 fprintf (f, "*** Edge (entry, %d) appears to not have an index\n",
7782 if (EDGE_INDEX (elist, ENTRY_BLOCK_PTR, BASIC_BLOCK (succ))
7783 != EDGE_INDEX_NO_EDGE && found_edge == 0)
7784 fprintf (f, "*** Edge (entry, %d) has index %d, but no edge exists\n",
7785 succ, EDGE_INDEX (elist, ENTRY_BLOCK_PTR,
7786 BASIC_BLOCK (succ)));
7788 for (pred = 0; pred < n_basic_blocks; pred++)
7790 basic_block p = BASIC_BLOCK (pred);
7791 basic_block s = EXIT_BLOCK_PTR;
7795 for (e = p->succ; e; e = e->succ_next)
7801 for (e = s->pred; e; e = e->pred_next)
7807 if (EDGE_INDEX (elist, BASIC_BLOCK (pred), EXIT_BLOCK_PTR)
7808 == EDGE_INDEX_NO_EDGE && found_edge != 0)
7809 fprintf (f, "*** Edge (%d, exit) appears to not have an index\n",
7811 if (EDGE_INDEX (elist, BASIC_BLOCK (pred), EXIT_BLOCK_PTR)
7812 != EDGE_INDEX_NO_EDGE && found_edge == 0)
7813 fprintf (f, "*** Edge (%d, exit) has index %d, but no edge exists\n",
7814 pred, EDGE_INDEX (elist, BASIC_BLOCK (pred),
7819 /* This routine will determine what, if any, edge there is between
7820 a specified predecessor and successor. */
7823 find_edge_index (edge_list, pred, succ)
7824 struct edge_list *edge_list;
7825 basic_block pred, succ;
7828 for (x = 0; x < NUM_EDGES (edge_list); x++)
7830 if (INDEX_EDGE_PRED_BB (edge_list, x) == pred
7831 && INDEX_EDGE_SUCC_BB (edge_list, x) == succ)
7834 return (EDGE_INDEX_NO_EDGE);
7837 /* This function will remove an edge from the flow graph. */
7843 edge last_pred = NULL;
7844 edge last_succ = NULL;
7846 basic_block src, dest;
7849 for (tmp = src->succ; tmp && tmp != e; tmp = tmp->succ_next)
7855 last_succ->succ_next = e->succ_next;
7857 src->succ = e->succ_next;
7859 for (tmp = dest->pred; tmp && tmp != e; tmp = tmp->pred_next)
7865 last_pred->pred_next = e->pred_next;
7867 dest->pred = e->pred_next;
7873 /* This routine will remove any fake successor edges for a basic block.
7874 When the edge is removed, it is also removed from whatever predecessor
7878 remove_fake_successors (bb)
7882 for (e = bb->succ; e;)
7886 if ((tmp->flags & EDGE_FAKE) == EDGE_FAKE)
7891 /* This routine will remove all fake edges from the flow graph. If
7892 we remove all fake successors, it will automatically remove all
7893 fake predecessors. */
7896 remove_fake_edges ()
7900 for (x = 0; x < n_basic_blocks; x++)
7901 remove_fake_successors (BASIC_BLOCK (x));
7903 /* We've handled all successors except the entry block's. */
7904 remove_fake_successors (ENTRY_BLOCK_PTR);
7907 /* This function will add a fake edge between any block which has no
7908 successors, and the exit block. Some data flow equations require these
7912 add_noreturn_fake_exit_edges ()
7916 for (x = 0; x < n_basic_blocks; x++)
7917 if (BASIC_BLOCK (x)->succ == NULL)
7918 make_edge (NULL, BASIC_BLOCK (x), EXIT_BLOCK_PTR, EDGE_FAKE);
7921 /* This function adds a fake edge between any infinite loops to the
7922 exit block. Some optimizations require a path from each node to
7925 See also Morgan, Figure 3.10, pp. 82-83.
7927 The current implementation is ugly, not attempting to minimize the
7928 number of inserted fake edges. To reduce the number of fake edges
7929 to insert, add fake edges from _innermost_ loops containing only
7930 nodes not reachable from the exit block. */
7933 connect_infinite_loops_to_exit ()
7935 basic_block unvisited_block;
7937 /* Perform depth-first search in the reverse graph to find nodes
7938 reachable from the exit block. */
7939 struct depth_first_search_dsS dfs_ds;
7941 flow_dfs_compute_reverse_init (&dfs_ds);
7942 flow_dfs_compute_reverse_add_bb (&dfs_ds, EXIT_BLOCK_PTR);
7944 /* Repeatedly add fake edges, updating the unreachable nodes. */
7947 unvisited_block = flow_dfs_compute_reverse_execute (&dfs_ds);
7948 if (!unvisited_block)
7950 make_edge (NULL, unvisited_block, EXIT_BLOCK_PTR, EDGE_FAKE);
7951 flow_dfs_compute_reverse_add_bb (&dfs_ds, unvisited_block);
7954 flow_dfs_compute_reverse_finish (&dfs_ds);
7959 /* Redirect an edge's successor from one block to another. */
7962 redirect_edge_succ (e, new_succ)
7964 basic_block new_succ;
7968 /* Disconnect the edge from the old successor block. */
7969 for (pe = &e->dest->pred; *pe != e; pe = &(*pe)->pred_next)
7971 *pe = (*pe)->pred_next;
7973 /* Reconnect the edge to the new successor block. */
7974 e->pred_next = new_succ->pred;
7979 /* Redirect an edge's predecessor from one block to another. */
7982 redirect_edge_pred (e, new_pred)
7984 basic_block new_pred;
7988 /* Disconnect the edge from the old predecessor block. */
7989 for (pe = &e->src->succ; *pe != e; pe = &(*pe)->succ_next)
7991 *pe = (*pe)->succ_next;
7993 /* Reconnect the edge to the new predecessor block. */
7994 e->succ_next = new_pred->succ;
7999 /* Dump the list of basic blocks in the bitmap NODES. */
8002 flow_nodes_print (str, nodes, file)
8004 const sbitmap nodes;
8012 fprintf (file, "%s { ", str);
8013 EXECUTE_IF_SET_IN_SBITMAP (nodes, 0, node, {fprintf (file, "%d ", node);});
8014 fputs ("}\n", file);
8018 /* Dump the list of edges in the array EDGE_LIST. */
8021 flow_edge_list_print (str, edge_list, num_edges, file)
8023 const edge *edge_list;
8032 fprintf (file, "%s { ", str);
8033 for (i = 0; i < num_edges; i++)
8034 fprintf (file, "%d->%d ", edge_list[i]->src->index,
8035 edge_list[i]->dest->index);
8036 fputs ("}\n", file);
8040 /* Dump loop related CFG information. */
8043 flow_loops_cfg_dump (loops, file)
8044 const struct loops *loops;
8049 if (! loops->num || ! file || ! loops->cfg.dom)
8052 for (i = 0; i < n_basic_blocks; i++)
8056 fprintf (file, ";; %d succs { ", i);
8057 for (succ = BASIC_BLOCK (i)->succ; succ; succ = succ->succ_next)
8058 fprintf (file, "%d ", succ->dest->index);
8059 flow_nodes_print ("} dom", loops->cfg.dom[i], file);
8062 /* Dump the DFS node order. */
8063 if (loops->cfg.dfs_order)
8065 fputs (";; DFS order: ", file);
8066 for (i = 0; i < n_basic_blocks; i++)
8067 fprintf (file, "%d ", loops->cfg.dfs_order[i]);
8070 /* Dump the reverse completion node order. */
8071 if (loops->cfg.rc_order)
8073 fputs (";; RC order: ", file);
8074 for (i = 0; i < n_basic_blocks; i++)
8075 fprintf (file, "%d ", loops->cfg.rc_order[i]);
8080 /* Return non-zero if the nodes of LOOP are a subset of OUTER. */
8083 flow_loop_nested_p (outer, loop)
8087 return sbitmap_a_subset_b_p (loop->nodes, outer->nodes);
8091 /* Dump the loop information specified by LOOP to the stream FILE
8092 using auxiliary dump callback function LOOP_DUMP_AUX if non null. */
8094 flow_loop_dump (loop, file, loop_dump_aux, verbose)
8095 const struct loop *loop;
8097 void (*loop_dump_aux) PARAMS((const struct loop *, FILE *, int));
8100 if (! loop || ! loop->header)
8103 fprintf (file, ";;\n;; Loop %d (%d to %d):%s%s\n",
8104 loop->num, INSN_UID (loop->first->head),
8105 INSN_UID (loop->last->end),
8106 loop->shared ? " shared" : "",
8107 loop->invalid ? " invalid" : "");
8108 fprintf (file, ";; header %d, latch %d, pre-header %d, first %d, last %d\n",
8109 loop->header->index, loop->latch->index,
8110 loop->pre_header ? loop->pre_header->index : -1,
8111 loop->first->index, loop->last->index);
8112 fprintf (file, ";; depth %d, level %d, outer %ld\n",
8113 loop->depth, loop->level,
8114 (long) (loop->outer ? loop->outer->num : -1));
8116 if (loop->pre_header_edges)
8117 flow_edge_list_print (";; pre-header edges", loop->pre_header_edges,
8118 loop->num_pre_header_edges, file);
8119 flow_edge_list_print (";; entry edges", loop->entry_edges,
8120 loop->num_entries, file);
8121 fprintf (file, ";; %d", loop->num_nodes);
8122 flow_nodes_print (" nodes", loop->nodes, file);
8123 flow_edge_list_print (";; exit edges", loop->exit_edges,
8124 loop->num_exits, file);
8125 if (loop->exits_doms)
8126 flow_nodes_print (";; exit doms", loop->exits_doms, file);
8128 loop_dump_aux (loop, file, verbose);
8132 /* Dump the loop information specified by LOOPS to the stream FILE,
8133 using auxiliary dump callback function LOOP_DUMP_AUX if non null. */
8135 flow_loops_dump (loops, file, loop_dump_aux, verbose)
8136 const struct loops *loops;
8138 void (*loop_dump_aux) PARAMS((const struct loop *, FILE *, int));
8144 num_loops = loops->num;
8145 if (! num_loops || ! file)
8148 fprintf (file, ";; %d loops found, %d levels\n",
8149 num_loops, loops->levels);
8151 for (i = 0; i < num_loops; i++)
8153 struct loop *loop = &loops->array[i];
8155 flow_loop_dump (loop, file, loop_dump_aux, verbose);
8161 for (j = 0; j < i; j++)
8163 struct loop *oloop = &loops->array[j];
8165 if (loop->header == oloop->header)
8170 smaller = loop->num_nodes < oloop->num_nodes;
8172 /* If the union of LOOP and OLOOP is different than
8173 the larger of LOOP and OLOOP then LOOP and OLOOP
8174 must be disjoint. */
8175 disjoint = ! flow_loop_nested_p (smaller ? loop : oloop,
8176 smaller ? oloop : loop);
8178 ";; loop header %d shared by loops %d, %d %s\n",
8179 loop->header->index, i, j,
8180 disjoint ? "disjoint" : "nested");
8187 flow_loops_cfg_dump (loops, file);
8191 /* Free all the memory allocated for LOOPS. */
8194 flow_loops_free (loops)
8195 struct loops *loops;
8204 /* Free the loop descriptors. */
8205 for (i = 0; i < loops->num; i++)
8207 struct loop *loop = &loops->array[i];
8209 if (loop->pre_header_edges)
8210 free (loop->pre_header_edges);
8212 sbitmap_free (loop->nodes);
8213 if (loop->entry_edges)
8214 free (loop->entry_edges);
8215 if (loop->exit_edges)
8216 free (loop->exit_edges);
8217 if (loop->exits_doms)
8218 sbitmap_free (loop->exits_doms);
8220 free (loops->array);
8221 loops->array = NULL;
8224 sbitmap_vector_free (loops->cfg.dom);
8225 if (loops->cfg.dfs_order)
8226 free (loops->cfg.dfs_order);
8228 if (loops->shared_headers)
8229 sbitmap_free (loops->shared_headers);
8234 /* Find the entry edges into the loop with header HEADER and nodes
8235 NODES and store in ENTRY_EDGES array. Return the number of entry
8236 edges from the loop. */
8239 flow_loop_entry_edges_find (header, nodes, entry_edges)
8241 const sbitmap nodes;
8247 *entry_edges = NULL;
8250 for (e = header->pred; e; e = e->pred_next)
8252 basic_block src = e->src;
8254 if (src == ENTRY_BLOCK_PTR || ! TEST_BIT (nodes, src->index))
8261 *entry_edges = (edge *) xmalloc (num_entries * sizeof (edge *));
8264 for (e = header->pred; e; e = e->pred_next)
8266 basic_block src = e->src;
8268 if (src == ENTRY_BLOCK_PTR || ! TEST_BIT (nodes, src->index))
8269 (*entry_edges)[num_entries++] = e;
8276 /* Find the exit edges from the loop using the bitmap of loop nodes
8277 NODES and store in EXIT_EDGES array. Return the number of
8278 exit edges from the loop. */
8281 flow_loop_exit_edges_find (nodes, exit_edges)
8282 const sbitmap nodes;
8291 /* Check all nodes within the loop to see if there are any
8292 successors not in the loop. Note that a node may have multiple
8293 exiting edges ????? A node can have one jumping edge and one fallthru
8294 edge so only one of these can exit the loop. */
8296 EXECUTE_IF_SET_IN_SBITMAP (nodes, 0, node, {
8297 for (e = BASIC_BLOCK (node)->succ; e; e = e->succ_next)
8299 basic_block dest = e->dest;
8301 if (dest == EXIT_BLOCK_PTR || ! TEST_BIT (nodes, dest->index))
8309 *exit_edges = (edge *) xmalloc (num_exits * sizeof (edge *));
8311 /* Store all exiting edges into an array. */
8313 EXECUTE_IF_SET_IN_SBITMAP (nodes, 0, node, {
8314 for (e = BASIC_BLOCK (node)->succ; e; e = e->succ_next)
8316 basic_block dest = e->dest;
8318 if (dest == EXIT_BLOCK_PTR || ! TEST_BIT (nodes, dest->index))
8319 (*exit_edges)[num_exits++] = e;
8327 /* Find the nodes contained within the loop with header HEADER and
8328 latch LATCH and store in NODES. Return the number of nodes within
8332 flow_loop_nodes_find (header, latch, nodes)
8341 stack = (basic_block *) xmalloc (n_basic_blocks * sizeof (basic_block));
8344 /* Start with only the loop header in the set of loop nodes. */
8345 sbitmap_zero (nodes);
8346 SET_BIT (nodes, header->index);
8348 header->loop_depth++;
8350 /* Push the loop latch on to the stack. */
8351 if (! TEST_BIT (nodes, latch->index))
8353 SET_BIT (nodes, latch->index);
8354 latch->loop_depth++;
8356 stack[sp++] = latch;
8365 for (e = node->pred; e; e = e->pred_next)
8367 basic_block ancestor = e->src;
8369 /* If each ancestor not marked as part of loop, add to set of
8370 loop nodes and push on to stack. */
8371 if (ancestor != ENTRY_BLOCK_PTR
8372 && ! TEST_BIT (nodes, ancestor->index))
8374 SET_BIT (nodes, ancestor->index);
8375 ancestor->loop_depth++;
8377 stack[sp++] = ancestor;
8385 /* Compute the depth first search order and store in the array
8386 DFS_ORDER if non-zero, marking the nodes visited in VISITED. If
8387 RC_ORDER is non-zero, return the reverse completion number for each
8388 node. Returns the number of nodes visited. A depth first search
8389 tries to get as far away from the starting point as quickly as
8393 flow_depth_first_order_compute (dfs_order, rc_order)
8400 int rcnum = n_basic_blocks - 1;
8403 /* Allocate stack for back-tracking up CFG. */
8404 stack = (edge *) xmalloc ((n_basic_blocks + 1) * sizeof (edge));
8407 /* Allocate bitmap to track nodes that have been visited. */
8408 visited = sbitmap_alloc (n_basic_blocks);
8410 /* None of the nodes in the CFG have been visited yet. */
8411 sbitmap_zero (visited);
8413 /* Push the first edge on to the stack. */
8414 stack[sp++] = ENTRY_BLOCK_PTR->succ;
8422 /* Look at the edge on the top of the stack. */
8427 /* Check if the edge destination has been visited yet. */
8428 if (dest != EXIT_BLOCK_PTR && ! TEST_BIT (visited, dest->index))
8430 /* Mark that we have visited the destination. */
8431 SET_BIT (visited, dest->index);
8434 dfs_order[dfsnum++] = dest->index;
8438 /* Since the DEST node has been visited for the first
8439 time, check its successors. */
8440 stack[sp++] = dest->succ;
8444 /* There are no successors for the DEST node so assign
8445 its reverse completion number. */
8447 rc_order[rcnum--] = dest->index;
8452 if (! e->succ_next && src != ENTRY_BLOCK_PTR)
8454 /* There are no more successors for the SRC node
8455 so assign its reverse completion number. */
8457 rc_order[rcnum--] = src->index;
8461 stack[sp - 1] = e->succ_next;
8468 sbitmap_free (visited);
8470 /* The number of nodes visited should not be greater than
8472 if (dfsnum > n_basic_blocks)
8475 /* There are some nodes left in the CFG that are unreachable. */
8476 if (dfsnum < n_basic_blocks)
8481 /* Compute the depth first search order on the _reverse_ graph and
8482 store in the array DFS_ORDER, marking the nodes visited in VISITED.
8483 Returns the number of nodes visited.
8485 The computation is split into three pieces:
8487 flow_dfs_compute_reverse_init () creates the necessary data
8490 flow_dfs_compute_reverse_add_bb () adds a basic block to the data
8491 structures. The block will start the search.
8493 flow_dfs_compute_reverse_execute () continues (or starts) the
8494 search using the block on the top of the stack, stopping when the
8497 flow_dfs_compute_reverse_finish () destroys the necessary data
8500 Thus, the user will probably call ..._init(), call ..._add_bb() to
8501 add a beginning basic block to the stack, call ..._execute(),
8502 possibly add another bb to the stack and again call ..._execute(),
8503 ..., and finally call _finish(). */
8505 /* Initialize the data structures used for depth-first search on the
8506 reverse graph. If INITIALIZE_STACK is nonzero, the exit block is
8507 added to the basic block stack. DATA is the current depth-first
8508 search context. If INITIALIZE_STACK is non-zero, there is an
8509 element on the stack. */
8512 flow_dfs_compute_reverse_init (data)
8513 depth_first_search_ds data;
8515 /* Allocate stack for back-tracking up CFG. */
8517 (basic_block *) xmalloc ((n_basic_blocks - (INVALID_BLOCK + 1))
8518 * sizeof (basic_block));
8521 /* Allocate bitmap to track nodes that have been visited. */
8522 data->visited_blocks = sbitmap_alloc (n_basic_blocks - (INVALID_BLOCK + 1));
8524 /* None of the nodes in the CFG have been visited yet. */
8525 sbitmap_zero (data->visited_blocks);
8530 /* Add the specified basic block to the top of the dfs data
8531 structures. When the search continues, it will start at the
8535 flow_dfs_compute_reverse_add_bb (data, bb)
8536 depth_first_search_ds data;
8539 data->stack[data->sp++] = bb;
8543 /* Continue the depth-first search through the reverse graph starting
8544 with the block at the stack's top and ending when the stack is
8545 empty. Visited nodes are marked. Returns an unvisited basic
8546 block, or NULL if there is none available. */
8549 flow_dfs_compute_reverse_execute (data)
8550 depth_first_search_ds data;
8556 while (data->sp > 0)
8558 bb = data->stack[--data->sp];
8560 /* Mark that we have visited this node. */
8561 if (!TEST_BIT (data->visited_blocks, bb->index - (INVALID_BLOCK + 1)))
8563 SET_BIT (data->visited_blocks, bb->index - (INVALID_BLOCK + 1));
8565 /* Perform depth-first search on adjacent vertices. */
8566 for (e = bb->pred; e; e = e->pred_next)
8567 flow_dfs_compute_reverse_add_bb (data, e->src);
8571 /* Determine if there are unvisited basic blocks. */
8572 for (i = n_basic_blocks - (INVALID_BLOCK + 1); --i >= 0;)
8573 if (!TEST_BIT (data->visited_blocks, i))
8574 return BASIC_BLOCK (i + (INVALID_BLOCK + 1));
8578 /* Destroy the data structures needed for depth-first search on the
8582 flow_dfs_compute_reverse_finish (data)
8583 depth_first_search_ds data;
8586 sbitmap_free (data->visited_blocks);
8591 /* Find the root node of the loop pre-header extended basic block and
8592 the edges along the trace from the root node to the loop header. */
8595 flow_loop_pre_header_scan (loop)
8601 loop->num_pre_header_edges = 0;
8603 if (loop->num_entries != 1)
8606 ebb = loop->entry_edges[0]->src;
8608 if (ebb != ENTRY_BLOCK_PTR)
8612 /* Count number of edges along trace from loop header to
8613 root of pre-header extended basic block. Usually this is
8614 only one or two edges. */
8616 while (ebb->pred->src != ENTRY_BLOCK_PTR && ! ebb->pred->pred_next)
8618 ebb = ebb->pred->src;
8622 loop->pre_header_edges = (edge *) xmalloc (num * sizeof (edge *));
8623 loop->num_pre_header_edges = num;
8625 /* Store edges in order that they are followed. The source
8626 of the first edge is the root node of the pre-header extended
8627 basic block and the destination of the last last edge is
8629 for (e = loop->entry_edges[0]; num; e = e->src->pred)
8631 loop->pre_header_edges[--num] = e;
8637 /* Return the block for the pre-header of the loop with header
8638 HEADER where DOM specifies the dominator information. Return NULL if
8639 there is no pre-header. */
8642 flow_loop_pre_header_find (header, dom)
8646 basic_block pre_header;
8649 /* If block p is a predecessor of the header and is the only block
8650 that the header does not dominate, then it is the pre-header. */
8652 for (e = header->pred; e; e = e->pred_next)
8654 basic_block node = e->src;
8656 if (node != ENTRY_BLOCK_PTR
8657 && ! TEST_BIT (dom[node->index], header->index))
8659 if (pre_header == NULL)
8663 /* There are multiple edges into the header from outside
8664 the loop so there is no pre-header block. */
8673 /* Add LOOP to the loop hierarchy tree where PREVLOOP was the loop
8674 previously added. The insertion algorithm assumes that the loops
8675 are added in the order found by a depth first search of the CFG. */
8678 flow_loop_tree_node_add (prevloop, loop)
8679 struct loop *prevloop;
8683 if (flow_loop_nested_p (prevloop, loop))
8685 prevloop->inner = loop;
8686 loop->outer = prevloop;
8690 while (prevloop->outer)
8692 if (flow_loop_nested_p (prevloop->outer, loop))
8694 prevloop->next = loop;
8695 loop->outer = prevloop->outer;
8698 prevloop = prevloop->outer;
8701 prevloop->next = loop;
8705 /* Build the loop hierarchy tree for LOOPS. */
8708 flow_loops_tree_build (loops)
8709 struct loops *loops;
8714 num_loops = loops->num;
8718 /* Root the loop hierarchy tree with the first loop found.
8719 Since we used a depth first search this should be the
8721 loops->tree = &loops->array[0];
8722 loops->tree->outer = loops->tree->inner = loops->tree->next = NULL;
8724 /* Add the remaining loops to the tree. */
8725 for (i = 1; i < num_loops; i++)
8726 flow_loop_tree_node_add (&loops->array[i - 1], &loops->array[i]);
8729 /* Helper function to compute loop nesting depth and enclosed loop level
8730 for the natural loop specified by LOOP at the loop depth DEPTH.
8731 Returns the loop level. */
8734 flow_loop_level_compute (loop, depth)
8744 /* Traverse loop tree assigning depth and computing level as the
8745 maximum level of all the inner loops of this loop. The loop
8746 level is equivalent to the height of the loop in the loop tree
8747 and corresponds to the number of enclosed loop levels (including
8749 for (inner = loop->inner; inner; inner = inner->next)
8753 ilevel = flow_loop_level_compute (inner, depth + 1) + 1;
8758 loop->level = level;
8759 loop->depth = depth;
8763 /* Compute the loop nesting depth and enclosed loop level for the loop
8764 hierarchy tree specfied by LOOPS. Return the maximum enclosed loop
8768 flow_loops_level_compute (loops)
8769 struct loops *loops;
8775 /* Traverse all the outer level loops. */
8776 for (loop = loops->tree; loop; loop = loop->next)
8778 level = flow_loop_level_compute (loop, 1);
8786 /* Scan a single natural loop specified by LOOP collecting information
8787 about it specified by FLAGS. */
8790 flow_loop_scan (loops, loop, flags)
8791 struct loops *loops;
8795 /* Determine prerequisites. */
8796 if ((flags & LOOP_EXITS_DOMS) && ! loop->exit_edges)
8797 flags |= LOOP_EXIT_EDGES;
8799 if (flags & LOOP_ENTRY_EDGES)
8801 /* Find edges which enter the loop header.
8802 Note that the entry edges should only
8803 enter the header of a natural loop. */
8805 = flow_loop_entry_edges_find (loop->header,
8807 &loop->entry_edges);
8810 if (flags & LOOP_EXIT_EDGES)
8812 /* Find edges which exit the loop. */
8814 = flow_loop_exit_edges_find (loop->nodes,
8818 if (flags & LOOP_EXITS_DOMS)
8822 /* Determine which loop nodes dominate all the exits
8824 loop->exits_doms = sbitmap_alloc (n_basic_blocks);
8825 sbitmap_copy (loop->exits_doms, loop->nodes);
8826 for (j = 0; j < loop->num_exits; j++)
8827 sbitmap_a_and_b (loop->exits_doms, loop->exits_doms,
8828 loops->cfg.dom[loop->exit_edges[j]->src->index]);
8830 /* The header of a natural loop must dominate
8832 if (! TEST_BIT (loop->exits_doms, loop->header->index))
8836 if (flags & LOOP_PRE_HEADER)
8838 /* Look to see if the loop has a pre-header node. */
8840 = flow_loop_pre_header_find (loop->header, loops->cfg.dom);
8842 /* Find the blocks within the extended basic block of
8843 the loop pre-header. */
8844 flow_loop_pre_header_scan (loop);
8850 /* Find all the natural loops in the function and save in LOOPS structure
8851 and recalculate loop_depth information in basic block structures.
8852 FLAGS controls which loop information is collected.
8853 Return the number of natural loops found. */
8856 flow_loops_find (loops, flags)
8857 struct loops *loops;
8869 /* This function cannot be repeatedly called with different
8870 flags to build up the loop information. The loop tree
8871 must always be built if this function is called. */
8872 if (! (flags & LOOP_TREE))
8875 memset (loops, 0, sizeof (*loops));
8877 /* Taking care of this degenerate case makes the rest of
8878 this code simpler. */
8879 if (n_basic_blocks == 0)
8885 /* Compute the dominators. */
8886 dom = sbitmap_vector_alloc (n_basic_blocks, n_basic_blocks);
8887 calculate_dominance_info (NULL, dom, CDI_DOMINATORS);
8889 /* Count the number of loop edges (back edges). This should be the
8890 same as the number of natural loops. */
8893 for (b = 0; b < n_basic_blocks; b++)
8897 header = BASIC_BLOCK (b);
8898 header->loop_depth = 0;
8900 for (e = header->pred; e; e = e->pred_next)
8902 basic_block latch = e->src;
8904 /* Look for back edges where a predecessor is dominated
8905 by this block. A natural loop has a single entry
8906 node (header) that dominates all the nodes in the
8907 loop. It also has single back edge to the header
8908 from a latch node. Note that multiple natural loops
8909 may share the same header. */
8910 if (b != header->index)
8913 if (latch != ENTRY_BLOCK_PTR && TEST_BIT (dom[latch->index], b))
8920 /* Compute depth first search order of the CFG so that outer
8921 natural loops will be found before inner natural loops. */
8922 dfs_order = (int *) xmalloc (n_basic_blocks * sizeof (int));
8923 rc_order = (int *) xmalloc (n_basic_blocks * sizeof (int));
8924 flow_depth_first_order_compute (dfs_order, rc_order);
8926 /* Save CFG derived information to avoid recomputing it. */
8927 loops->cfg.dom = dom;
8928 loops->cfg.dfs_order = dfs_order;
8929 loops->cfg.rc_order = rc_order;
8931 /* Allocate loop structures. */
8933 = (struct loop *) xcalloc (num_loops, sizeof (struct loop));
8935 headers = sbitmap_alloc (n_basic_blocks);
8936 sbitmap_zero (headers);
8938 loops->shared_headers = sbitmap_alloc (n_basic_blocks);
8939 sbitmap_zero (loops->shared_headers);
8941 /* Find and record information about all the natural loops
8944 for (b = 0; b < n_basic_blocks; b++)
8948 /* Search the nodes of the CFG in reverse completion order
8949 so that we can find outer loops first. */
8950 header = BASIC_BLOCK (rc_order[b]);
8952 /* Look for all the possible latch blocks for this header. */
8953 for (e = header->pred; e; e = e->pred_next)
8955 basic_block latch = e->src;
8957 /* Look for back edges where a predecessor is dominated
8958 by this block. A natural loop has a single entry
8959 node (header) that dominates all the nodes in the
8960 loop. It also has single back edge to the header
8961 from a latch node. Note that multiple natural loops
8962 may share the same header. */
8963 if (latch != ENTRY_BLOCK_PTR
8964 && TEST_BIT (dom[latch->index], header->index))
8968 loop = loops->array + num_loops;
8970 loop->header = header;
8971 loop->latch = latch;
8972 loop->num = num_loops;
8979 for (i = 0; i < num_loops; i++)
8981 struct loop *loop = &loops->array[i];
8983 /* Keep track of blocks that are loop headers so
8984 that we can tell which loops should be merged. */
8985 if (TEST_BIT (headers, loop->header->index))
8986 SET_BIT (loops->shared_headers, loop->header->index);
8987 SET_BIT (headers, loop->header->index);
8989 /* Find nodes contained within the loop. */
8990 loop->nodes = sbitmap_alloc (n_basic_blocks);
8992 = flow_loop_nodes_find (loop->header, loop->latch, loop->nodes);
8994 /* Compute first and last blocks within the loop.
8995 These are often the same as the loop header and
8996 loop latch respectively, but this is not always
8999 = BASIC_BLOCK (sbitmap_first_set_bit (loop->nodes));
9001 = BASIC_BLOCK (sbitmap_last_set_bit (loop->nodes));
9003 flow_loop_scan (loops, loop, flags);
9006 /* Natural loops with shared headers may either be disjoint or
9007 nested. Disjoint loops with shared headers cannot be inner
9008 loops and should be merged. For now just mark loops that share
9010 for (i = 0; i < num_loops; i++)
9011 if (TEST_BIT (loops->shared_headers, loops->array[i].header->index))
9012 loops->array[i].shared = 1;
9014 sbitmap_free (headers);
9017 loops->num = num_loops;
9019 /* Build the loop hierarchy tree. */
9020 flow_loops_tree_build (loops);
9022 /* Assign the loop nesting depth and enclosed loop level for each
9024 loops->levels = flow_loops_level_compute (loops);
9030 /* Update the information regarding the loops in the CFG
9031 specified by LOOPS. */
9033 flow_loops_update (loops, flags)
9034 struct loops *loops;
9037 /* One day we may want to update the current loop data. For now
9038 throw away the old stuff and rebuild what we need. */
9040 flow_loops_free (loops);
9042 return flow_loops_find (loops, flags);
9046 /* Return non-zero if edge E enters header of LOOP from outside of LOOP. */
9049 flow_loop_outside_edge_p (loop, e)
9050 const struct loop *loop;
9053 if (e->dest != loop->header)
9055 return (e->src == ENTRY_BLOCK_PTR)
9056 || ! TEST_BIT (loop->nodes, e->src->index);
9059 /* Clear LOG_LINKS fields of insns in a chain.
9060 Also clear the global_live_at_{start,end} fields of the basic block
9064 clear_log_links (insns)
9070 for (i = insns; i; i = NEXT_INSN (i))
9074 for (b = 0; b < n_basic_blocks; b++)
9076 basic_block bb = BASIC_BLOCK (b);
9078 bb->global_live_at_start = NULL;
9079 bb->global_live_at_end = NULL;
9082 ENTRY_BLOCK_PTR->global_live_at_end = NULL;
9083 EXIT_BLOCK_PTR->global_live_at_start = NULL;
9086 /* Given a register bitmap, turn on the bits in a HARD_REG_SET that
9087 correspond to the hard registers, if any, set in that map. This
9088 could be done far more efficiently by having all sorts of special-cases
9089 with moving single words, but probably isn't worth the trouble. */
9092 reg_set_to_hard_reg_set (to, from)
9098 EXECUTE_IF_SET_IN_BITMAP
9101 if (i >= FIRST_PSEUDO_REGISTER)
9103 SET_HARD_REG_BIT (*to, i);
9107 /* Called once at intialization time. */
9112 static int initialized;
9116 gcc_obstack_init (&flow_obstack);
9117 flow_firstobj = (char *) obstack_alloc (&flow_obstack, 0);
9122 obstack_free (&flow_obstack, flow_firstobj);
9123 flow_firstobj = (char *) obstack_alloc (&flow_obstack, 0);