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 */
214 NULL, /* local_set */
215 NULL, /* cond_local_set */
216 NULL, /* global_live_at_start */
217 NULL, /* global_live_at_end */
219 EXIT_BLOCK, /* index */
225 /* Nonzero if the second flow pass has completed. */
228 /* Maximum register number used in this function, plus one. */
232 /* Indexed by n, giving various register information */
234 varray_type reg_n_info;
236 /* Size of a regset for the current function,
237 in (1) bytes and (2) elements. */
242 /* Regset of regs live when calls to `setjmp'-like functions happen. */
243 /* ??? Does this exist only for the setjmp-clobbered warning message? */
245 regset regs_live_at_setjmp;
247 /* List made of EXPR_LIST rtx's which gives pairs of pseudo registers
248 that have to go in the same hard reg.
249 The first two regs in the list are a pair, and the next two
250 are another pair, etc. */
253 /* Callback that determines if it's ok for a function to have no
254 noreturn attribute. */
255 int (*lang_missing_noreturn_ok_p) PARAMS ((tree));
257 /* Set of registers that may be eliminable. These are handled specially
258 in updating regs_ever_live. */
260 static HARD_REG_SET elim_reg_set;
262 /* The basic block structure for every insn, indexed by uid. */
264 varray_type basic_block_for_insn;
266 /* The labels mentioned in non-jump rtl. Valid during find_basic_blocks. */
267 /* ??? Should probably be using LABEL_NUSES instead. It would take a
268 bit of surgery to be able to use or co-opt the routines in jump. */
270 static rtx label_value_list;
271 static rtx tail_recursion_label_list;
273 /* Holds information for tracking conditional register life information. */
274 struct reg_cond_life_info
276 /* A boolean expression of conditions under which a register is dead. */
278 /* Conditions under which a register is dead at the basic block end. */
281 /* A boolean expression of conditions under which a register has been
285 /* ??? Could store mask of bytes that are dead, so that we could finally
286 track lifetimes of multi-word registers accessed via subregs. */
289 /* For use in communicating between propagate_block and its subroutines.
290 Holds all information needed to compute life and def-use information. */
292 struct propagate_block_info
294 /* The basic block we're considering. */
297 /* Bit N is set if register N is conditionally or unconditionally live. */
300 /* Bit N is set if register N is set this insn. */
303 /* Element N is the next insn that uses (hard or pseudo) register N
304 within the current basic block; or zero, if there is no such insn. */
307 /* Contains a list of all the MEMs we are tracking for dead store
311 /* If non-null, record the set of registers set unconditionally in the
315 /* If non-null, record the set of registers set conditionally in the
317 regset cond_local_set;
319 #ifdef HAVE_conditional_execution
320 /* Indexed by register number, holds a reg_cond_life_info for each
321 register that is not unconditionally live or dead. */
322 splay_tree reg_cond_dead;
324 /* Bit N is set if register N is in an expression in reg_cond_dead. */
328 /* The length of mem_set_list. */
329 int mem_set_list_len;
331 /* Non-zero if the value of CC0 is live. */
334 /* Flags controling the set of information propagate_block collects. */
338 /* Maximum length of pbi->mem_set_list before we start dropping
339 new elements on the floor. */
340 #define MAX_MEM_SET_LIST_LEN 100
342 /* Store the data structures necessary for depth-first search. */
343 struct depth_first_search_dsS {
344 /* stack for backtracking during the algorithm */
347 /* number of edges in the stack. That is, positions 0, ..., sp-1
351 /* record of basic blocks already seen by depth-first search */
352 sbitmap visited_blocks;
354 typedef struct depth_first_search_dsS *depth_first_search_ds;
356 /* Have print_rtl_and_abort give the same information that fancy_abort
358 #define print_rtl_and_abort() \
359 print_rtl_and_abort_fcn (__FILE__, __LINE__, __FUNCTION__)
361 /* Forward declarations */
362 static int count_basic_blocks PARAMS ((rtx));
363 static void find_basic_blocks_1 PARAMS ((rtx));
364 static rtx find_label_refs PARAMS ((rtx, rtx));
365 static void clear_edges PARAMS ((void));
366 static void make_edges PARAMS ((rtx));
367 static void make_label_edge PARAMS ((sbitmap *, basic_block,
369 static void make_eh_edge PARAMS ((sbitmap *, basic_block, rtx));
370 static void mark_critical_edges PARAMS ((void));
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 void try_merge_blocks PARAMS ((void));
385 static void tidy_fallthru_edges PARAMS ((void));
386 static int verify_wide_reg_1 PARAMS ((rtx *, void *));
387 static void verify_wide_reg PARAMS ((int, rtx, rtx));
388 static void verify_local_live_at_start PARAMS ((regset, basic_block));
389 static int noop_move_p PARAMS ((rtx));
390 static void delete_noop_moves PARAMS ((rtx));
391 static void notice_stack_pointer_modification_1 PARAMS ((rtx, rtx, void *));
392 static void notice_stack_pointer_modification PARAMS ((rtx));
393 static void mark_reg PARAMS ((rtx, void *));
394 static void mark_regs_live_at_end PARAMS ((regset));
395 static int set_phi_alternative_reg PARAMS ((rtx, int, int, void *));
396 static void calculate_global_regs_live PARAMS ((sbitmap, sbitmap, int));
397 static void propagate_block_delete_insn PARAMS ((basic_block, rtx));
398 static rtx propagate_block_delete_libcall PARAMS ((basic_block, rtx, rtx));
399 static int insn_dead_p PARAMS ((struct propagate_block_info *,
401 static int libcall_dead_p PARAMS ((struct propagate_block_info *,
403 static void mark_set_regs PARAMS ((struct propagate_block_info *,
405 static void mark_set_1 PARAMS ((struct propagate_block_info *,
406 enum rtx_code, rtx, rtx,
408 #ifdef HAVE_conditional_execution
409 static int mark_regno_cond_dead PARAMS ((struct propagate_block_info *,
411 static void free_reg_cond_life_info PARAMS ((splay_tree_value));
412 static int flush_reg_cond_reg_1 PARAMS ((splay_tree_node, void *));
413 static void flush_reg_cond_reg PARAMS ((struct propagate_block_info *,
415 static rtx elim_reg_cond PARAMS ((rtx, unsigned int));
416 static rtx ior_reg_cond PARAMS ((rtx, rtx, int));
417 static rtx not_reg_cond PARAMS ((rtx));
418 static rtx and_reg_cond PARAMS ((rtx, rtx, int));
421 static void attempt_auto_inc PARAMS ((struct propagate_block_info *,
422 rtx, rtx, rtx, rtx, rtx));
423 static void find_auto_inc PARAMS ((struct propagate_block_info *,
425 static int try_pre_increment_1 PARAMS ((struct propagate_block_info *,
427 static int try_pre_increment PARAMS ((rtx, rtx, HOST_WIDE_INT));
429 static void mark_used_reg PARAMS ((struct propagate_block_info *,
431 static void mark_used_regs PARAMS ((struct propagate_block_info *,
433 void dump_flow_info PARAMS ((FILE *));
434 void debug_flow_info PARAMS ((void));
435 static void dump_edge_info PARAMS ((FILE *, edge, int));
436 static void print_rtl_and_abort_fcn PARAMS ((const char *, int,
440 static void invalidate_mems_from_autoinc PARAMS ((struct propagate_block_info *,
442 static void invalidate_mems_from_set PARAMS ((struct propagate_block_info *,
444 static void remove_fake_successors PARAMS ((basic_block));
445 static void flow_nodes_print PARAMS ((const char *, const sbitmap,
447 static void flow_edge_list_print PARAMS ((const char *, const edge *,
449 static void flow_loops_cfg_dump PARAMS ((const struct loops *,
451 static int flow_loop_nested_p PARAMS ((struct loop *,
453 static int flow_loop_entry_edges_find PARAMS ((basic_block, const sbitmap,
455 static int flow_loop_exit_edges_find PARAMS ((const sbitmap, edge **));
456 static int flow_loop_nodes_find PARAMS ((basic_block, basic_block, sbitmap));
457 static int flow_depth_first_order_compute PARAMS ((int *, int *));
458 static void flow_dfs_compute_reverse_init
459 PARAMS ((depth_first_search_ds));
460 static void flow_dfs_compute_reverse_add_bb
461 PARAMS ((depth_first_search_ds, basic_block));
462 static basic_block flow_dfs_compute_reverse_execute
463 PARAMS ((depth_first_search_ds));
464 static void flow_dfs_compute_reverse_finish
465 PARAMS ((depth_first_search_ds));
466 static void flow_loop_pre_header_scan PARAMS ((struct loop *));
467 static basic_block flow_loop_pre_header_find PARAMS ((basic_block,
469 static void flow_loop_tree_node_add PARAMS ((struct loop *, struct loop *));
470 static void flow_loops_tree_build PARAMS ((struct loops *));
471 static int flow_loop_level_compute PARAMS ((struct loop *, int));
472 static int flow_loops_level_compute PARAMS ((struct loops *));
473 static void allocate_bb_life_data PARAMS ((void));
474 static void find_sub_basic_blocks PARAMS ((basic_block));
476 /* Find basic blocks of the current function.
477 F is the first insn of the function and NREGS the number of register
481 find_basic_blocks (f, nregs, file)
483 int nregs ATTRIBUTE_UNUSED;
484 FILE *file ATTRIBUTE_UNUSED;
488 /* Flush out existing data. */
489 if (basic_block_info != NULL)
495 /* Clear bb->aux on all extant basic blocks. We'll use this as a
496 tag for reuse during create_basic_block, just in case some pass
497 copies around basic block notes improperly. */
498 for (i = 0; i < n_basic_blocks; ++i)
499 BASIC_BLOCK (i)->aux = NULL;
501 VARRAY_FREE (basic_block_info);
504 n_basic_blocks = count_basic_blocks (f);
506 /* Size the basic block table. The actual structures will be allocated
507 by find_basic_blocks_1, since we want to keep the structure pointers
508 stable across calls to find_basic_blocks. */
509 /* ??? This whole issue would be much simpler if we called find_basic_blocks
510 exactly once, and thereafter we don't have a single long chain of
511 instructions at all until close to the end of compilation when we
512 actually lay them out. */
514 VARRAY_BB_INIT (basic_block_info, n_basic_blocks, "basic_block_info");
516 find_basic_blocks_1 (f);
518 /* Record the block to which an insn belongs. */
519 /* ??? This should be done another way, by which (perhaps) a label is
520 tagged directly with the basic block that it starts. It is used for
521 more than that currently, but IMO that is the only valid use. */
523 max_uid = get_max_uid ();
525 /* Leave space for insns life_analysis makes in some cases for auto-inc.
526 These cases are rare, so we don't need too much space. */
527 max_uid += max_uid / 10;
530 compute_bb_for_insn (max_uid);
532 /* Discover the edges of our cfg. */
533 make_edges (label_value_list);
535 /* Do very simple cleanup now, for the benefit of code that runs between
536 here and cleanup_cfg, e.g. thread_prologue_and_epilogue_insns. */
537 tidy_fallthru_edges ();
539 mark_critical_edges ();
541 #ifdef ENABLE_CHECKING
547 check_function_return_warnings ()
549 if (warn_missing_noreturn
550 && !TREE_THIS_VOLATILE (cfun->decl)
551 && EXIT_BLOCK_PTR->pred == NULL
552 && (lang_missing_noreturn_ok_p
553 && !lang_missing_noreturn_ok_p (cfun->decl)))
554 warning ("function might be possible candidate for attribute `noreturn'");
556 /* If we have a path to EXIT, then we do return. */
557 if (TREE_THIS_VOLATILE (cfun->decl)
558 && EXIT_BLOCK_PTR->pred != NULL)
559 warning ("`noreturn' function does return");
561 /* If the clobber_return_insn appears in some basic block, then we
562 do reach the end without returning a value. */
563 else if (warn_return_type
564 && cfun->x_clobber_return_insn != NULL
565 && EXIT_BLOCK_PTR->pred != NULL)
567 int max_uid = get_max_uid ();
569 /* If clobber_return_insn was excised by jump1, then renumber_insns
570 can make max_uid smaller than the number still recorded in our rtx.
571 That's fine, since this is a quick way of verifying that the insn
572 is no longer in the chain. */
573 if (INSN_UID (cfun->x_clobber_return_insn) < max_uid)
575 /* Recompute insn->block mapping, since the initial mapping is
576 set before we delete unreachable blocks. */
577 compute_bb_for_insn (max_uid);
579 if (BLOCK_FOR_INSN (cfun->x_clobber_return_insn) != NULL)
580 warning ("control reaches end of non-void function");
585 /* Count the basic blocks of the function. */
588 count_basic_blocks (f)
592 register RTX_CODE prev_code;
593 register int count = 0;
594 int saw_abnormal_edge = 0;
596 prev_code = JUMP_INSN;
597 for (insn = f; insn; insn = NEXT_INSN (insn))
599 enum rtx_code code = GET_CODE (insn);
601 if (code == CODE_LABEL
602 || (GET_RTX_CLASS (code) == 'i'
603 && (prev_code == JUMP_INSN
604 || prev_code == BARRIER
605 || saw_abnormal_edge)))
607 saw_abnormal_edge = 0;
611 /* Record whether this insn created an edge. */
612 if (code == CALL_INSN)
616 /* If there is a nonlocal goto label and the specified
617 region number isn't -1, we have an edge. */
618 if (nonlocal_goto_handler_labels
619 && ((note = find_reg_note (insn, REG_EH_REGION, NULL_RTX)) == 0
620 || INTVAL (XEXP (note, 0)) >= 0))
621 saw_abnormal_edge = 1;
623 else if (can_throw_internal (insn))
624 saw_abnormal_edge = 1;
626 else if (flag_non_call_exceptions
628 && can_throw_internal (insn))
629 saw_abnormal_edge = 1;
635 /* The rest of the compiler works a bit smoother when we don't have to
636 check for the edge case of do-nothing functions with no basic blocks. */
639 emit_insn (gen_rtx_USE (VOIDmode, const0_rtx));
646 /* Scan a list of insns for labels referred to other than by jumps.
647 This is used to scan the alternatives of a call placeholder. */
649 find_label_refs (f, lvl)
655 for (insn = f; insn; insn = NEXT_INSN (insn))
656 if (INSN_P (insn) && GET_CODE (insn) != JUMP_INSN)
660 /* Make a list of all labels referred to other than by jumps
661 (which just don't have the REG_LABEL notes).
663 Make a special exception for labels followed by an ADDR*VEC,
664 as this would be a part of the tablejump setup code.
666 Make a special exception to registers loaded with label
667 values just before jump insns that use them. */
669 for (note = REG_NOTES (insn); note; note = XEXP (note, 1))
670 if (REG_NOTE_KIND (note) == REG_LABEL)
672 rtx lab = XEXP (note, 0), next;
674 if ((next = next_nonnote_insn (lab)) != NULL
675 && GET_CODE (next) == JUMP_INSN
676 && (GET_CODE (PATTERN (next)) == ADDR_VEC
677 || GET_CODE (PATTERN (next)) == ADDR_DIFF_VEC))
679 else if (GET_CODE (lab) == NOTE)
681 else if (GET_CODE (NEXT_INSN (insn)) == JUMP_INSN
682 && find_reg_note (NEXT_INSN (insn), REG_LABEL, lab))
685 lvl = alloc_EXPR_LIST (0, XEXP (note, 0), lvl);
692 /* Assume that someone emitted code with control flow instructions to the
693 basic block. Update the data structure. */
695 find_sub_basic_blocks (bb)
698 rtx first_insn = bb->head, insn;
700 edge succ_list = bb->succ;
701 rtx jump_insn = NULL_RTX;
705 basic_block first_bb = bb, last_bb;
708 if (GET_CODE (first_insn) == LABEL_REF)
709 first_insn = NEXT_INSN (first_insn);
710 first_insn = NEXT_INSN (first_insn);
714 /* Scan insn chain and try to find new basic block boundaries. */
717 enum rtx_code code = GET_CODE (insn);
721 /* We need some special care for those expressions. */
722 if (GET_CODE (PATTERN (insn)) == ADDR_VEC
723 || GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC)
732 /* On code label, split current basic block. */
734 falltru = split_block (bb, PREV_INSN (insn));
739 remove_edge (falltru);
743 if (LABEL_ALTERNATE_NAME (insn))
744 make_edge (NULL, ENTRY_BLOCK_PTR, bb, 0);
747 /* In case we've previously split insn on the JUMP_INSN, move the
748 block header to proper place. */
751 falltru = split_block (bb, PREV_INSN (insn));
761 insn = NEXT_INSN (insn);
763 /* Last basic block must end in the original BB end. */
767 /* Wire in the original edges for last basic block. */
770 bb->succ = succ_list;
772 succ_list->src = bb, succ_list = succ_list->succ_next;
775 bb->succ = succ_list;
777 /* Now re-scan and wire in all edges. This expect simple (conditional)
778 jumps at the end of each new basic blocks. */
780 for (i = first_bb->index; i < last_bb->index; i++)
782 bb = BASIC_BLOCK (i);
783 if (GET_CODE (bb->end) == JUMP_INSN)
785 mark_jump_label (PATTERN (bb->end), bb->end, 0, 0);
786 make_label_edge (NULL, bb, JUMP_LABEL (bb->end), 0);
788 insn = NEXT_INSN (insn);
792 /* Find all basic blocks of the function whose first insn is F.
794 Collect and return a list of labels whose addresses are taken. This
795 will be used in make_edges for use with computed gotos. */
798 find_basic_blocks_1 (f)
801 register rtx insn, next;
803 rtx bb_note = NULL_RTX;
809 /* We process the instructions in a slightly different way than we did
810 previously. This is so that we see a NOTE_BASIC_BLOCK after we have
811 closed out the previous block, so that it gets attached at the proper
812 place. Since this form should be equivalent to the previous,
813 count_basic_blocks continues to use the old form as a check. */
815 for (insn = f; insn; insn = next)
817 enum rtx_code code = GET_CODE (insn);
819 next = NEXT_INSN (insn);
825 int kind = NOTE_LINE_NUMBER (insn);
827 /* Look for basic block notes with which to keep the
828 basic_block_info pointers stable. Unthread the note now;
829 we'll put it back at the right place in create_basic_block.
830 Or not at all if we've already found a note in this block. */
831 if (kind == NOTE_INSN_BASIC_BLOCK)
833 if (bb_note == NULL_RTX)
836 next = flow_delete_insn (insn);
842 /* A basic block starts at a label. If we've closed one off due
843 to a barrier or some such, no need to do it again. */
844 if (head != NULL_RTX)
846 /* While we now have edge lists with which other portions of
847 the compiler might determine a call ending a basic block
848 does not imply an abnormal edge, it will be a bit before
849 everything can be updated. So continue to emit a noop at
850 the end of such a block. */
851 if (GET_CODE (end) == CALL_INSN && ! SIBLING_CALL_P (end))
853 rtx nop = gen_rtx_USE (VOIDmode, const0_rtx);
854 end = emit_insn_after (nop, end);
857 create_basic_block (i++, head, end, bb_note);
865 /* A basic block ends at a jump. */
866 if (head == NULL_RTX)
870 /* ??? Make a special check for table jumps. The way this
871 happens is truly and amazingly gross. We are about to
872 create a basic block that contains just a code label and
873 an addr*vec jump insn. Worse, an addr_diff_vec creates
874 its own natural loop.
876 Prevent this bit of brain damage, pasting things together
877 correctly in make_edges.
879 The correct solution involves emitting the table directly
880 on the tablejump instruction as a note, or JUMP_LABEL. */
882 if (GET_CODE (PATTERN (insn)) == ADDR_VEC
883 || GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC)
891 goto new_bb_inclusive;
894 /* A basic block ends at a barrier. It may be that an unconditional
895 jump already closed the basic block -- no need to do it again. */
896 if (head == NULL_RTX)
899 /* While we now have edge lists with which other portions of the
900 compiler might determine a call ending a basic block does not
901 imply an abnormal edge, it will be a bit before everything can
902 be updated. So continue to emit a noop at the end of such a
904 if (GET_CODE (end) == CALL_INSN && ! SIBLING_CALL_P (end))
906 rtx nop = gen_rtx_USE (VOIDmode, const0_rtx);
907 end = emit_insn_after (nop, end);
909 goto new_bb_exclusive;
913 /* Record whether this call created an edge. */
914 rtx note = find_reg_note (insn, REG_EH_REGION, NULL_RTX);
915 int region = (note ? INTVAL (XEXP (note, 0)) : 0);
917 if (GET_CODE (PATTERN (insn)) == CALL_PLACEHOLDER)
919 /* Scan each of the alternatives for label refs. */
920 lvl = find_label_refs (XEXP (PATTERN (insn), 0), lvl);
921 lvl = find_label_refs (XEXP (PATTERN (insn), 1), lvl);
922 lvl = find_label_refs (XEXP (PATTERN (insn), 2), lvl);
923 /* Record its tail recursion label, if any. */
924 if (XEXP (PATTERN (insn), 3) != NULL_RTX)
925 trll = alloc_EXPR_LIST (0, XEXP (PATTERN (insn), 3), trll);
928 /* A basic block ends at a call that can either throw or
929 do a non-local goto. */
930 if ((nonlocal_goto_handler_labels && region >= 0)
931 || can_throw_internal (insn))
934 if (head == NULL_RTX)
939 create_basic_block (i++, head, end, bb_note);
940 head = end = NULL_RTX;
948 /* Non-call exceptions generate new blocks just like calls. */
949 if (flag_non_call_exceptions && can_throw_internal (insn))
950 goto new_bb_inclusive;
952 if (head == NULL_RTX)
961 if (GET_CODE (insn) == INSN || GET_CODE (insn) == CALL_INSN)
965 /* Make a list of all labels referred to other than by jumps.
967 Make a special exception for labels followed by an ADDR*VEC,
968 as this would be a part of the tablejump setup code.
970 Make a special exception to registers loaded with label
971 values just before jump insns that use them. */
973 for (note = REG_NOTES (insn); note; note = XEXP (note, 1))
974 if (REG_NOTE_KIND (note) == REG_LABEL)
976 rtx lab = XEXP (note, 0), next;
978 if ((next = next_nonnote_insn (lab)) != NULL
979 && GET_CODE (next) == JUMP_INSN
980 && (GET_CODE (PATTERN (next)) == ADDR_VEC
981 || GET_CODE (PATTERN (next)) == ADDR_DIFF_VEC))
983 else if (GET_CODE (lab) == NOTE)
985 else if (GET_CODE (NEXT_INSN (insn)) == JUMP_INSN
986 && find_reg_note (NEXT_INSN (insn), REG_LABEL, lab))
989 lvl = alloc_EXPR_LIST (0, XEXP (note, 0), lvl);
994 if (head != NULL_RTX)
995 create_basic_block (i++, head, end, bb_note);
997 flow_delete_insn (bb_note);
999 if (i != n_basic_blocks)
1002 label_value_list = lvl;
1003 tail_recursion_label_list = trll;
1006 /* Tidy the CFG by deleting unreachable code and whatnot. */
1011 delete_unreachable_blocks ();
1012 try_merge_blocks ();
1013 mark_critical_edges ();
1015 /* Kill the data we won't maintain. */
1016 free_EXPR_LIST_list (&label_value_list);
1017 free_EXPR_LIST_list (&tail_recursion_label_list);
1020 /* Create a new basic block consisting of the instructions between
1021 HEAD and END inclusive. Reuses the note and basic block struct
1022 in BB_NOTE, if any. */
1025 create_basic_block (index, head, end, bb_note)
1027 rtx head, end, bb_note;
1032 && ! RTX_INTEGRATED_P (bb_note)
1033 && (bb = NOTE_BASIC_BLOCK (bb_note)) != NULL
1036 /* If we found an existing note, thread it back onto the chain. */
1040 if (GET_CODE (head) == CODE_LABEL)
1044 after = PREV_INSN (head);
1048 if (after != bb_note && NEXT_INSN (after) != bb_note)
1049 reorder_insns (bb_note, bb_note, after);
1053 /* Otherwise we must create a note and a basic block structure.
1054 Since we allow basic block structs in rtl, give the struct
1055 the same lifetime by allocating it off the function obstack
1056 rather than using malloc. */
1058 bb = (basic_block) obstack_alloc (&flow_obstack, sizeof (*bb));
1059 memset (bb, 0, sizeof (*bb));
1061 if (GET_CODE (head) == CODE_LABEL)
1062 bb_note = emit_note_after (NOTE_INSN_BASIC_BLOCK, head);
1065 bb_note = emit_note_before (NOTE_INSN_BASIC_BLOCK, head);
1068 NOTE_BASIC_BLOCK (bb_note) = bb;
1071 /* Always include the bb note in the block. */
1072 if (NEXT_INSN (end) == bb_note)
1078 BASIC_BLOCK (index) = bb;
1080 /* Tag the block so that we know it has been used when considering
1081 other basic block notes. */
1085 /* Records the basic block struct in BB_FOR_INSN, for every instruction
1086 indexed by INSN_UID. MAX is the size of the array. */
1089 compute_bb_for_insn (max)
1094 if (basic_block_for_insn)
1095 VARRAY_FREE (basic_block_for_insn);
1096 VARRAY_BB_INIT (basic_block_for_insn, max, "basic_block_for_insn");
1098 for (i = 0; i < n_basic_blocks; ++i)
1100 basic_block bb = BASIC_BLOCK (i);
1107 int uid = INSN_UID (insn);
1109 VARRAY_BB (basic_block_for_insn, uid) = bb;
1112 insn = NEXT_INSN (insn);
1117 /* Free the memory associated with the edge structures. */
1125 for (i = 0; i < n_basic_blocks; ++i)
1127 basic_block bb = BASIC_BLOCK (i);
1129 for (e = bb->succ; e; e = n)
1139 for (e = ENTRY_BLOCK_PTR->succ; e; e = n)
1145 ENTRY_BLOCK_PTR->succ = 0;
1146 EXIT_BLOCK_PTR->pred = 0;
1151 /* Identify the edges between basic blocks.
1153 NONLOCAL_LABEL_LIST is a list of non-local labels in the function. Blocks
1154 that are otherwise unreachable may be reachable with a non-local goto.
1156 BB_EH_END is an array indexed by basic block number in which we record
1157 the list of exception regions active at the end of the basic block. */
1160 make_edges (label_value_list)
1161 rtx label_value_list;
1164 sbitmap *edge_cache = NULL;
1166 /* Assume no computed jump; revise as we create edges. */
1167 current_function_has_computed_jump = 0;
1169 /* Heavy use of computed goto in machine-generated code can lead to
1170 nearly fully-connected CFGs. In that case we spend a significant
1171 amount of time searching the edge lists for duplicates. */
1172 if (forced_labels || label_value_list)
1174 edge_cache = sbitmap_vector_alloc (n_basic_blocks, n_basic_blocks);
1175 sbitmap_vector_zero (edge_cache, n_basic_blocks);
1178 /* By nature of the way these get numbered, block 0 is always the entry. */
1179 make_edge (edge_cache, ENTRY_BLOCK_PTR, BASIC_BLOCK (0), EDGE_FALLTHRU);
1181 for (i = 0; i < n_basic_blocks; ++i)
1183 basic_block bb = BASIC_BLOCK (i);
1186 int force_fallthru = 0;
1188 if (GET_CODE (bb->head) == CODE_LABEL
1189 && LABEL_ALTERNATE_NAME (bb->head))
1190 make_edge (NULL, ENTRY_BLOCK_PTR, bb, 0);
1192 /* Examine the last instruction of the block, and discover the
1193 ways we can leave the block. */
1196 code = GET_CODE (insn);
1199 if (code == JUMP_INSN)
1203 /* Recognize exception handling placeholders. */
1204 if (GET_CODE (PATTERN (insn)) == RESX)
1205 make_eh_edge (edge_cache, bb, insn);
1207 /* Recognize a non-local goto as a branch outside the
1208 current function. */
1209 else if (find_reg_note (insn, REG_NON_LOCAL_GOTO, NULL_RTX))
1212 /* ??? Recognize a tablejump and do the right thing. */
1213 else if ((tmp = JUMP_LABEL (insn)) != NULL_RTX
1214 && (tmp = NEXT_INSN (tmp)) != NULL_RTX
1215 && GET_CODE (tmp) == JUMP_INSN
1216 && (GET_CODE (PATTERN (tmp)) == ADDR_VEC
1217 || GET_CODE (PATTERN (tmp)) == ADDR_DIFF_VEC))
1222 if (GET_CODE (PATTERN (tmp)) == ADDR_VEC)
1223 vec = XVEC (PATTERN (tmp), 0);
1225 vec = XVEC (PATTERN (tmp), 1);
1227 for (j = GET_NUM_ELEM (vec) - 1; j >= 0; --j)
1228 make_label_edge (edge_cache, bb,
1229 XEXP (RTVEC_ELT (vec, j), 0), 0);
1231 /* Some targets (eg, ARM) emit a conditional jump that also
1232 contains the out-of-range target. Scan for these and
1233 add an edge if necessary. */
1234 if ((tmp = single_set (insn)) != NULL
1235 && SET_DEST (tmp) == pc_rtx
1236 && GET_CODE (SET_SRC (tmp)) == IF_THEN_ELSE
1237 && GET_CODE (XEXP (SET_SRC (tmp), 2)) == LABEL_REF)
1238 make_label_edge (edge_cache, bb,
1239 XEXP (XEXP (SET_SRC (tmp), 2), 0), 0);
1241 #ifdef CASE_DROPS_THROUGH
1242 /* Silly VAXen. The ADDR_VEC is going to be in the way of
1243 us naturally detecting fallthru into the next block. */
1248 /* If this is a computed jump, then mark it as reaching
1249 everything on the label_value_list and forced_labels list. */
1250 else if (computed_jump_p (insn))
1252 current_function_has_computed_jump = 1;
1254 for (x = label_value_list; x; x = XEXP (x, 1))
1255 make_label_edge (edge_cache, bb, XEXP (x, 0), EDGE_ABNORMAL);
1257 for (x = forced_labels; x; x = XEXP (x, 1))
1258 make_label_edge (edge_cache, bb, XEXP (x, 0), EDGE_ABNORMAL);
1261 /* Returns create an exit out. */
1262 else if (returnjump_p (insn))
1263 make_edge (edge_cache, bb, EXIT_BLOCK_PTR, 0);
1265 /* Otherwise, we have a plain conditional or unconditional jump. */
1268 if (! JUMP_LABEL (insn))
1270 make_label_edge (edge_cache, bb, JUMP_LABEL (insn), 0);
1274 /* If this is a sibling call insn, then this is in effect a
1275 combined call and return, and so we need an edge to the
1276 exit block. No need to worry about EH edges, since we
1277 wouldn't have created the sibling call in the first place. */
1279 if (code == CALL_INSN && SIBLING_CALL_P (insn))
1280 make_edge (edge_cache, bb, EXIT_BLOCK_PTR,
1281 EDGE_ABNORMAL | EDGE_ABNORMAL_CALL);
1283 /* If this is a CALL_INSN, then mark it as reaching the active EH
1284 handler for this CALL_INSN. If we're handling non-call
1285 exceptions then any insn can reach any of the active handlers.
1287 Also mark the CALL_INSN as reaching any nonlocal goto handler. */
1289 else if (code == CALL_INSN || flag_non_call_exceptions)
1291 /* Add any appropriate EH edges. */
1292 make_eh_edge (edge_cache, bb, insn);
1294 if (code == CALL_INSN && nonlocal_goto_handler_labels)
1296 /* ??? This could be made smarter: in some cases it's possible
1297 to tell that certain calls will not do a nonlocal goto.
1299 For example, if the nested functions that do the nonlocal
1300 gotos do not have their addresses taken, then only calls to
1301 those functions or to other nested functions that use them
1302 could possibly do nonlocal gotos. */
1303 /* We do know that a REG_EH_REGION note with a value less
1304 than 0 is guaranteed not to perform a non-local goto. */
1305 rtx note = find_reg_note (insn, REG_EH_REGION, NULL_RTX);
1306 if (!note || INTVAL (XEXP (note, 0)) >= 0)
1307 for (x = nonlocal_goto_handler_labels; x; x = XEXP (x, 1))
1308 make_label_edge (edge_cache, bb, XEXP (x, 0),
1309 EDGE_ABNORMAL | EDGE_ABNORMAL_CALL);
1313 /* Find out if we can drop through to the next block. */
1314 insn = next_nonnote_insn (insn);
1315 if (!insn || (i + 1 == n_basic_blocks && force_fallthru))
1316 make_edge (edge_cache, bb, EXIT_BLOCK_PTR, EDGE_FALLTHRU);
1317 else if (i + 1 < n_basic_blocks)
1319 rtx tmp = BLOCK_HEAD (i + 1);
1320 if (GET_CODE (tmp) == NOTE)
1321 tmp = next_nonnote_insn (tmp);
1322 if (force_fallthru || insn == tmp)
1323 make_edge (edge_cache, bb, BASIC_BLOCK (i + 1), EDGE_FALLTHRU);
1328 sbitmap_vector_free (edge_cache);
1331 /* Create an edge between two basic blocks. FLAGS are auxiliary information
1332 about the edge that is accumulated between calls. */
1335 make_edge (edge_cache, src, dst, flags)
1336 sbitmap *edge_cache;
1337 basic_block src, dst;
1343 /* Don't bother with edge cache for ENTRY or EXIT; there aren't that
1344 many edges to them, and we didn't allocate memory for it. */
1345 use_edge_cache = (edge_cache
1346 && src != ENTRY_BLOCK_PTR
1347 && dst != EXIT_BLOCK_PTR);
1349 /* Make sure we don't add duplicate edges. */
1350 switch (use_edge_cache)
1353 /* Quick test for non-existance of the edge. */
1354 if (! TEST_BIT (edge_cache[src->index], dst->index))
1357 /* The edge exists; early exit if no work to do. */
1363 for (e = src->succ; e; e = e->succ_next)
1372 e = (edge) xcalloc (1, sizeof (*e));
1375 e->succ_next = src->succ;
1376 e->pred_next = dst->pred;
1385 SET_BIT (edge_cache[src->index], dst->index);
1388 /* Create an edge from a basic block to a label. */
1391 make_label_edge (edge_cache, src, label, flags)
1392 sbitmap *edge_cache;
1397 if (GET_CODE (label) != CODE_LABEL)
1400 /* If the label was never emitted, this insn is junk, but avoid a
1401 crash trying to refer to BLOCK_FOR_INSN (label). This can happen
1402 as a result of a syntax error and a diagnostic has already been
1405 if (INSN_UID (label) == 0)
1408 make_edge (edge_cache, src, BLOCK_FOR_INSN (label), flags);
1411 /* Create the edges generated by INSN in REGION. */
1414 make_eh_edge (edge_cache, src, insn)
1415 sbitmap *edge_cache;
1419 int is_call = (GET_CODE (insn) == CALL_INSN ? EDGE_ABNORMAL_CALL : 0);
1422 handlers = reachable_handlers (insn);
1424 for (i = handlers; i; i = XEXP (i, 1))
1425 make_label_edge (edge_cache, src, XEXP (i, 0),
1426 EDGE_ABNORMAL | EDGE_EH | is_call);
1428 free_INSN_LIST_list (&handlers);
1431 /* Identify critical edges and set the bits appropriately. */
1434 mark_critical_edges ()
1436 int i, n = n_basic_blocks;
1439 /* We begin with the entry block. This is not terribly important now,
1440 but could be if a front end (Fortran) implemented alternate entry
1442 bb = ENTRY_BLOCK_PTR;
1449 /* (1) Critical edges must have a source with multiple successors. */
1450 if (bb->succ && bb->succ->succ_next)
1452 for (e = bb->succ; e; e = e->succ_next)
1454 /* (2) Critical edges must have a destination with multiple
1455 predecessors. Note that we know there is at least one
1456 predecessor -- the edge we followed to get here. */
1457 if (e->dest->pred->pred_next)
1458 e->flags |= EDGE_CRITICAL;
1460 e->flags &= ~EDGE_CRITICAL;
1465 for (e = bb->succ; e; e = e->succ_next)
1466 e->flags &= ~EDGE_CRITICAL;
1471 bb = BASIC_BLOCK (i);
1475 /* Split a block BB after insn INSN creating a new fallthru edge.
1476 Return the new edge. Note that to keep other parts of the compiler happy,
1477 this function renumbers all the basic blocks so that the new
1478 one has a number one greater than the block split. */
1481 split_block (bb, insn)
1491 /* There is no point splitting the block after its end. */
1492 if (bb->end == insn)
1495 /* Create the new structures. */
1496 new_bb = (basic_block) obstack_alloc (&flow_obstack, sizeof (*new_bb));
1497 new_edge = (edge) xcalloc (1, sizeof (*new_edge));
1500 memset (new_bb, 0, sizeof (*new_bb));
1502 new_bb->head = NEXT_INSN (insn);
1503 new_bb->end = bb->end;
1506 new_bb->succ = bb->succ;
1507 bb->succ = new_edge;
1508 new_bb->pred = new_edge;
1509 new_bb->count = bb->count;
1510 new_bb->loop_depth = bb->loop_depth;
1513 new_edge->dest = new_bb;
1514 new_edge->flags = EDGE_FALLTHRU;
1515 new_edge->probability = REG_BR_PROB_BASE;
1516 new_edge->count = bb->count;
1518 /* Redirect the src of the successor edges of bb to point to new_bb. */
1519 for (e = new_bb->succ; e; e = e->succ_next)
1522 /* Place the new block just after the block being split. */
1523 VARRAY_GROW (basic_block_info, ++n_basic_blocks);
1525 /* Some parts of the compiler expect blocks to be number in
1526 sequential order so insert the new block immediately after the
1527 block being split.. */
1529 for (i = n_basic_blocks - 1; i > j + 1; --i)
1531 basic_block tmp = BASIC_BLOCK (i - 1);
1532 BASIC_BLOCK (i) = tmp;
1536 BASIC_BLOCK (i) = new_bb;
1539 if (GET_CODE (new_bb->head) == CODE_LABEL)
1541 /* Create the basic block note. */
1542 bb_note = emit_note_after (NOTE_INSN_BASIC_BLOCK,
1544 NOTE_BASIC_BLOCK (bb_note) = new_bb;
1548 /* Create the basic block note. */
1549 bb_note = emit_note_before (NOTE_INSN_BASIC_BLOCK,
1551 NOTE_BASIC_BLOCK (bb_note) = new_bb;
1552 new_bb->head = bb_note;
1555 update_bb_for_insn (new_bb);
1557 if (bb->global_live_at_start)
1559 new_bb->global_live_at_start = OBSTACK_ALLOC_REG_SET (&flow_obstack);
1560 new_bb->global_live_at_end = OBSTACK_ALLOC_REG_SET (&flow_obstack);
1561 COPY_REG_SET (new_bb->global_live_at_end, bb->global_live_at_end);
1563 /* We now have to calculate which registers are live at the end
1564 of the split basic block and at the start of the new basic
1565 block. Start with those registers that are known to be live
1566 at the end of the original basic block and get
1567 propagate_block to determine which registers are live. */
1568 COPY_REG_SET (new_bb->global_live_at_start, bb->global_live_at_end);
1569 propagate_block (new_bb, new_bb->global_live_at_start, NULL, NULL, 0);
1570 COPY_REG_SET (bb->global_live_at_end,
1571 new_bb->global_live_at_start);
1578 /* Split a (typically critical) edge. Return the new block.
1579 Abort on abnormal edges.
1581 ??? The code generally expects to be called on critical edges.
1582 The case of a block ending in an unconditional jump to a
1583 block with multiple predecessors is not handled optimally. */
1586 split_edge (edge_in)
1589 basic_block old_pred, bb, old_succ;
1594 /* Abnormal edges cannot be split. */
1595 if ((edge_in->flags & EDGE_ABNORMAL) != 0)
1598 old_pred = edge_in->src;
1599 old_succ = edge_in->dest;
1601 /* Remove the existing edge from the destination's pred list. */
1604 for (pp = &old_succ->pred; *pp != edge_in; pp = &(*pp)->pred_next)
1606 *pp = edge_in->pred_next;
1607 edge_in->pred_next = NULL;
1610 /* Create the new structures. */
1611 bb = (basic_block) obstack_alloc (&flow_obstack, sizeof (*bb));
1612 edge_out = (edge) xcalloc (1, sizeof (*edge_out));
1615 memset (bb, 0, sizeof (*bb));
1617 /* ??? This info is likely going to be out of date very soon. */
1618 if (old_succ->global_live_at_start)
1620 bb->global_live_at_start = OBSTACK_ALLOC_REG_SET (&flow_obstack);
1621 bb->global_live_at_end = OBSTACK_ALLOC_REG_SET (&flow_obstack);
1622 COPY_REG_SET (bb->global_live_at_start, old_succ->global_live_at_start);
1623 COPY_REG_SET (bb->global_live_at_end, old_succ->global_live_at_start);
1628 bb->succ = edge_out;
1629 bb->count = edge_in->count;
1632 edge_in->flags &= ~EDGE_CRITICAL;
1634 edge_out->pred_next = old_succ->pred;
1635 edge_out->succ_next = NULL;
1637 edge_out->dest = old_succ;
1638 edge_out->flags = EDGE_FALLTHRU;
1639 edge_out->probability = REG_BR_PROB_BASE;
1640 edge_out->count = edge_in->count;
1642 old_succ->pred = edge_out;
1644 /* Tricky case -- if there existed a fallthru into the successor
1645 (and we're not it) we must add a new unconditional jump around
1646 the new block we're actually interested in.
1648 Further, if that edge is critical, this means a second new basic
1649 block must be created to hold it. In order to simplify correct
1650 insn placement, do this before we touch the existing basic block
1651 ordering for the block we were really wanting. */
1652 if ((edge_in->flags & EDGE_FALLTHRU) == 0)
1655 for (e = edge_out->pred_next; e; e = e->pred_next)
1656 if (e->flags & EDGE_FALLTHRU)
1661 basic_block jump_block;
1664 if ((e->flags & EDGE_CRITICAL) == 0
1665 && e->src != ENTRY_BLOCK_PTR)
1667 /* Non critical -- we can simply add a jump to the end
1668 of the existing predecessor. */
1669 jump_block = e->src;
1673 /* We need a new block to hold the jump. The simplest
1674 way to do the bulk of the work here is to recursively
1676 jump_block = split_edge (e);
1677 e = jump_block->succ;
1680 /* Now add the jump insn ... */
1681 pos = emit_jump_insn_after (gen_jump (old_succ->head),
1683 jump_block->end = pos;
1684 if (basic_block_for_insn)
1685 set_block_for_insn (pos, jump_block);
1686 emit_barrier_after (pos);
1688 /* ... let jump know that label is in use, ... */
1689 JUMP_LABEL (pos) = old_succ->head;
1690 ++LABEL_NUSES (old_succ->head);
1692 /* ... and clear fallthru on the outgoing edge. */
1693 e->flags &= ~EDGE_FALLTHRU;
1695 /* Continue splitting the interesting edge. */
1699 /* Place the new block just in front of the successor. */
1700 VARRAY_GROW (basic_block_info, ++n_basic_blocks);
1701 if (old_succ == EXIT_BLOCK_PTR)
1702 j = n_basic_blocks - 1;
1704 j = old_succ->index;
1705 for (i = n_basic_blocks - 1; i > j; --i)
1707 basic_block tmp = BASIC_BLOCK (i - 1);
1708 BASIC_BLOCK (i) = tmp;
1711 BASIC_BLOCK (i) = bb;
1714 /* Create the basic block note.
1716 Where we place the note can have a noticable impact on the generated
1717 code. Consider this cfg:
1727 If we need to insert an insn on the edge from block 0 to block 1,
1728 we want to ensure the instructions we insert are outside of any
1729 loop notes that physically sit between block 0 and block 1. Otherwise
1730 we confuse the loop optimizer into thinking the loop is a phony. */
1731 if (old_succ != EXIT_BLOCK_PTR
1732 && PREV_INSN (old_succ->head)
1733 && GET_CODE (PREV_INSN (old_succ->head)) == NOTE
1734 && NOTE_LINE_NUMBER (PREV_INSN (old_succ->head)) == NOTE_INSN_LOOP_BEG)
1735 bb_note = emit_note_before (NOTE_INSN_BASIC_BLOCK,
1736 PREV_INSN (old_succ->head));
1737 else if (old_succ != EXIT_BLOCK_PTR)
1738 bb_note = emit_note_before (NOTE_INSN_BASIC_BLOCK, old_succ->head);
1740 bb_note = emit_note_after (NOTE_INSN_BASIC_BLOCK, get_last_insn ());
1741 NOTE_BASIC_BLOCK (bb_note) = bb;
1742 bb->head = bb->end = bb_note;
1744 /* Not quite simple -- for non-fallthru edges, we must adjust the
1745 predecessor's jump instruction to target our new block. */
1746 if ((edge_in->flags & EDGE_FALLTHRU) == 0)
1748 rtx tmp, insn = old_pred->end;
1749 rtx old_label = old_succ->head;
1750 rtx new_label = gen_label_rtx ();
1752 if (GET_CODE (insn) != JUMP_INSN)
1755 /* ??? Recognize a tablejump and adjust all matching cases. */
1756 if ((tmp = JUMP_LABEL (insn)) != NULL_RTX
1757 && (tmp = NEXT_INSN (tmp)) != NULL_RTX
1758 && GET_CODE (tmp) == JUMP_INSN
1759 && (GET_CODE (PATTERN (tmp)) == ADDR_VEC
1760 || GET_CODE (PATTERN (tmp)) == ADDR_DIFF_VEC))
1765 if (GET_CODE (PATTERN (tmp)) == ADDR_VEC)
1766 vec = XVEC (PATTERN (tmp), 0);
1768 vec = XVEC (PATTERN (tmp), 1);
1770 for (j = GET_NUM_ELEM (vec) - 1; j >= 0; --j)
1771 if (XEXP (RTVEC_ELT (vec, j), 0) == old_label)
1773 RTVEC_ELT (vec, j) = gen_rtx_LABEL_REF (VOIDmode, new_label);
1774 --LABEL_NUSES (old_label);
1775 ++LABEL_NUSES (new_label);
1778 /* Handle casesi dispatch insns */
1779 if ((tmp = single_set (insn)) != NULL
1780 && SET_DEST (tmp) == pc_rtx
1781 && GET_CODE (SET_SRC (tmp)) == IF_THEN_ELSE
1782 && GET_CODE (XEXP (SET_SRC (tmp), 2)) == LABEL_REF
1783 && XEXP (XEXP (SET_SRC (tmp), 2), 0) == old_label)
1785 XEXP (SET_SRC (tmp), 2) = gen_rtx_LABEL_REF (VOIDmode,
1787 --LABEL_NUSES (old_label);
1788 ++LABEL_NUSES (new_label);
1793 /* This would have indicated an abnormal edge. */
1794 if (computed_jump_p (insn))
1797 /* A return instruction can't be redirected. */
1798 if (returnjump_p (insn))
1801 /* If the insn doesn't go where we think, we're confused. */
1802 if (JUMP_LABEL (insn) != old_label)
1805 redirect_jump (insn, new_label, 0);
1808 emit_label_before (new_label, bb_note);
1809 bb->head = new_label;
1815 /* Queue instructions for insertion on an edge between two basic blocks.
1816 The new instructions and basic blocks (if any) will not appear in the
1817 CFG until commit_edge_insertions is called. */
1820 insert_insn_on_edge (pattern, e)
1824 /* We cannot insert instructions on an abnormal critical edge.
1825 It will be easier to find the culprit if we die now. */
1826 if ((e->flags & (EDGE_ABNORMAL|EDGE_CRITICAL))
1827 == (EDGE_ABNORMAL|EDGE_CRITICAL))
1830 if (e->insns == NULL_RTX)
1833 push_to_sequence (e->insns);
1835 emit_insn (pattern);
1837 e->insns = get_insns ();
1841 /* Update the CFG for the instructions queued on edge E. */
1844 commit_one_edge_insertion (e)
1847 rtx before = NULL_RTX, after = NULL_RTX, insns, tmp, last;
1850 /* Pull the insns off the edge now since the edge might go away. */
1852 e->insns = NULL_RTX;
1854 /* Figure out where to put these things. If the destination has
1855 one predecessor, insert there. Except for the exit block. */
1856 if (e->dest->pred->pred_next == NULL
1857 && e->dest != EXIT_BLOCK_PTR)
1861 /* Get the location correct wrt a code label, and "nice" wrt
1862 a basic block note, and before everything else. */
1864 if (GET_CODE (tmp) == CODE_LABEL)
1865 tmp = NEXT_INSN (tmp);
1866 if (NOTE_INSN_BASIC_BLOCK_P (tmp))
1867 tmp = NEXT_INSN (tmp);
1868 if (tmp == bb->head)
1871 after = PREV_INSN (tmp);
1874 /* If the source has one successor and the edge is not abnormal,
1875 insert there. Except for the entry block. */
1876 else if ((e->flags & EDGE_ABNORMAL) == 0
1877 && e->src->succ->succ_next == NULL
1878 && e->src != ENTRY_BLOCK_PTR)
1881 /* It is possible to have a non-simple jump here. Consider a target
1882 where some forms of unconditional jumps clobber a register. This
1883 happens on the fr30 for example.
1885 We know this block has a single successor, so we can just emit
1886 the queued insns before the jump. */
1887 if (GET_CODE (bb->end) == JUMP_INSN)
1893 /* We'd better be fallthru, or we've lost track of what's what. */
1894 if ((e->flags & EDGE_FALLTHRU) == 0)
1901 /* Otherwise we must split the edge. */
1904 bb = split_edge (e);
1908 /* Now that we've found the spot, do the insertion. */
1910 /* Set the new block number for these insns, if structure is allocated. */
1911 if (basic_block_for_insn)
1914 for (i = insns; i != NULL_RTX; i = NEXT_INSN (i))
1915 set_block_for_insn (i, bb);
1920 emit_insns_before (insns, before);
1921 if (before == bb->head)
1924 last = prev_nonnote_insn (before);
1928 last = emit_insns_after (insns, after);
1929 if (after == bb->end)
1933 if (returnjump_p (last))
1935 /* ??? Remove all outgoing edges from BB and add one for EXIT.
1936 This is not currently a problem because this only happens
1937 for the (single) epilogue, which already has a fallthru edge
1941 if (e->dest != EXIT_BLOCK_PTR
1942 || e->succ_next != NULL
1943 || (e->flags & EDGE_FALLTHRU) == 0)
1945 e->flags &= ~EDGE_FALLTHRU;
1947 emit_barrier_after (last);
1951 flow_delete_insn (before);
1953 else if (GET_CODE (last) == JUMP_INSN)
1955 find_sub_basic_blocks (bb);
1958 /* Update the CFG for all queued instructions. */
1961 commit_edge_insertions ()
1966 #ifdef ENABLE_CHECKING
1967 verify_flow_info ();
1971 bb = ENTRY_BLOCK_PTR;
1976 for (e = bb->succ; e; e = next)
1978 next = e->succ_next;
1980 commit_one_edge_insertion (e);
1983 if (++i >= n_basic_blocks)
1985 bb = BASIC_BLOCK (i);
1989 /* Add fake edges to the function exit for any non constant calls in
1990 the bitmap of blocks specified by BLOCKS or to the whole CFG if
1991 BLOCKS is zero. Return the nuber of blocks that were split. */
1994 flow_call_edges_add (blocks)
1998 int blocks_split = 0;
2002 /* Map bb indicies into basic block pointers since split_block
2003 will renumber the basic blocks. */
2005 bbs = xmalloc (n_basic_blocks * sizeof (*bbs));
2009 for (i = 0; i < n_basic_blocks; i++)
2010 bbs[bb_num++] = BASIC_BLOCK (i);
2014 EXECUTE_IF_SET_IN_SBITMAP (blocks, 0, i,
2016 bbs[bb_num++] = BASIC_BLOCK (i);
2021 /* Now add fake edges to the function exit for any non constant
2022 calls since there is no way that we can determine if they will
2025 for (i = 0; i < bb_num; i++)
2027 basic_block bb = bbs[i];
2031 for (insn = bb->end; ; insn = prev_insn)
2033 prev_insn = PREV_INSN (insn);
2034 if (GET_CODE (insn) == CALL_INSN && ! CONST_CALL_P (insn))
2038 /* Note that the following may create a new basic block
2039 and renumber the existing basic blocks. */
2040 e = split_block (bb, insn);
2044 make_edge (NULL, bb, EXIT_BLOCK_PTR, EDGE_FAKE);
2046 if (insn == bb->head)
2052 verify_flow_info ();
2055 return blocks_split;
2058 /* Find unreachable blocks. An unreachable block will have NULL in
2059 block->aux, a non-NULL value indicates the block is reachable. */
2062 find_unreachable_blocks ()
2066 basic_block *tos, *worklist;
2069 tos = worklist = (basic_block *) xmalloc (sizeof (basic_block) * n);
2071 /* Use basic_block->aux as a marker. Clear them all. */
2073 for (i = 0; i < n; ++i)
2074 BASIC_BLOCK (i)->aux = NULL;
2076 /* Add our starting points to the worklist. Almost always there will
2077 be only one. It isn't inconcievable that we might one day directly
2078 support Fortran alternate entry points. */
2080 for (e = ENTRY_BLOCK_PTR->succ; e; e = e->succ_next)
2084 /* Mark the block with a handy non-null value. */
2088 /* Iterate: find everything reachable from what we've already seen. */
2090 while (tos != worklist)
2092 basic_block b = *--tos;
2094 for (e = b->succ; e; e = e->succ_next)
2105 /* Delete all unreachable basic blocks. */
2107 delete_unreachable_blocks ()
2111 find_unreachable_blocks ();
2113 /* Delete all unreachable basic blocks. Count down so that we
2114 don't interfere with the block renumbering that happens in
2115 flow_delete_block. */
2117 for (i = n_basic_blocks - 1; i >= 0; --i)
2119 basic_block b = BASIC_BLOCK (i);
2122 /* This block was found. Tidy up the mark. */
2125 flow_delete_block (b);
2128 tidy_fallthru_edges ();
2131 /* Return true if NOTE is not one of the ones that must be kept paired,
2132 so that we may simply delete them. */
2135 can_delete_note_p (note)
2138 return (NOTE_LINE_NUMBER (note) == NOTE_INSN_DELETED
2139 || NOTE_LINE_NUMBER (note) == NOTE_INSN_BASIC_BLOCK);
2142 /* Unlink a chain of insns between START and FINISH, leaving notes
2143 that must be paired. */
2146 flow_delete_insn_chain (start, finish)
2149 /* Unchain the insns one by one. It would be quicker to delete all
2150 of these with a single unchaining, rather than one at a time, but
2151 we need to keep the NOTE's. */
2157 next = NEXT_INSN (start);
2158 if (GET_CODE (start) == NOTE && !can_delete_note_p (start))
2160 else if (GET_CODE (start) == CODE_LABEL
2161 && ! can_delete_label_p (start))
2163 const char *name = LABEL_NAME (start);
2164 PUT_CODE (start, NOTE);
2165 NOTE_LINE_NUMBER (start) = NOTE_INSN_DELETED_LABEL;
2166 NOTE_SOURCE_FILE (start) = name;
2169 next = flow_delete_insn (start);
2171 if (start == finish)
2177 /* Delete the insns in a (non-live) block. We physically delete every
2178 non-deleted-note insn, and update the flow graph appropriately.
2180 Return nonzero if we deleted an exception handler. */
2182 /* ??? Preserving all such notes strikes me as wrong. It would be nice
2183 to post-process the stream to remove empty blocks, loops, ranges, etc. */
2186 flow_delete_block (b)
2189 int deleted_handler = 0;
2192 /* If the head of this block is a CODE_LABEL, then it might be the
2193 label for an exception handler which can't be reached.
2195 We need to remove the label from the exception_handler_label list
2196 and remove the associated NOTE_INSN_EH_REGION_BEG and
2197 NOTE_INSN_EH_REGION_END notes. */
2201 never_reached_warning (insn);
2203 if (GET_CODE (insn) == CODE_LABEL)
2204 maybe_remove_eh_handler (insn);
2206 /* Include any jump table following the basic block. */
2208 if (GET_CODE (end) == JUMP_INSN
2209 && (tmp = JUMP_LABEL (end)) != NULL_RTX
2210 && (tmp = NEXT_INSN (tmp)) != NULL_RTX
2211 && GET_CODE (tmp) == JUMP_INSN
2212 && (GET_CODE (PATTERN (tmp)) == ADDR_VEC
2213 || GET_CODE (PATTERN (tmp)) == ADDR_DIFF_VEC))
2216 /* Include any barrier that may follow the basic block. */
2217 tmp = next_nonnote_insn (end);
2218 if (tmp && GET_CODE (tmp) == BARRIER)
2221 /* Selectively delete the entire chain. */
2222 flow_delete_insn_chain (insn, end);
2224 /* Remove the edges into and out of this block. Note that there may
2225 indeed be edges in, if we are removing an unreachable loop. */
2229 for (e = b->pred; e; e = next)
2231 for (q = &e->src->succ; *q != e; q = &(*q)->succ_next)
2234 next = e->pred_next;
2238 for (e = b->succ; e; e = next)
2240 for (q = &e->dest->pred; *q != e; q = &(*q)->pred_next)
2243 next = e->succ_next;
2252 /* Remove the basic block from the array, and compact behind it. */
2255 return deleted_handler;
2258 /* Remove block B from the basic block array and compact behind it. */
2264 int i, n = n_basic_blocks;
2266 for (i = b->index; i + 1 < n; ++i)
2268 basic_block x = BASIC_BLOCK (i + 1);
2269 BASIC_BLOCK (i) = x;
2273 basic_block_info->num_elements--;
2277 /* Delete INSN by patching it out. Return the next insn. */
2280 flow_delete_insn (insn)
2283 rtx prev = PREV_INSN (insn);
2284 rtx next = NEXT_INSN (insn);
2287 PREV_INSN (insn) = NULL_RTX;
2288 NEXT_INSN (insn) = NULL_RTX;
2289 INSN_DELETED_P (insn) = 1;
2292 NEXT_INSN (prev) = next;
2294 PREV_INSN (next) = prev;
2296 set_last_insn (prev);
2298 if (GET_CODE (insn) == CODE_LABEL)
2299 remove_node_from_expr_list (insn, &nonlocal_goto_handler_labels);
2301 /* If deleting a jump, decrement the use count of the label. Deleting
2302 the label itself should happen in the normal course of block merging. */
2303 if (GET_CODE (insn) == JUMP_INSN
2304 && JUMP_LABEL (insn)
2305 && GET_CODE (JUMP_LABEL (insn)) == CODE_LABEL)
2306 LABEL_NUSES (JUMP_LABEL (insn))--;
2308 /* Also if deleting an insn that references a label. */
2309 else if ((note = find_reg_note (insn, REG_LABEL, NULL_RTX)) != NULL_RTX
2310 && GET_CODE (XEXP (note, 0)) == CODE_LABEL)
2311 LABEL_NUSES (XEXP (note, 0))--;
2316 /* True if a given label can be deleted. */
2319 can_delete_label_p (label)
2324 if (LABEL_PRESERVE_P (label))
2327 for (x = forced_labels; x; x = XEXP (x, 1))
2328 if (label == XEXP (x, 0))
2330 for (x = label_value_list; x; x = XEXP (x, 1))
2331 if (label == XEXP (x, 0))
2333 for (x = exception_handler_labels; x; x = XEXP (x, 1))
2334 if (label == XEXP (x, 0))
2337 /* User declared labels must be preserved. */
2338 if (LABEL_NAME (label) != 0)
2345 tail_recursion_label_p (label)
2350 for (x = tail_recursion_label_list; x; x = XEXP (x, 1))
2351 if (label == XEXP (x, 0))
2357 /* Blocks A and B are to be merged into a single block A. The insns
2358 are already contiguous, hence `nomove'. */
2361 merge_blocks_nomove (a, b)
2365 rtx b_head, b_end, a_end;
2366 rtx del_first = NULL_RTX, del_last = NULL_RTX;
2369 /* If there was a CODE_LABEL beginning B, delete it. */
2372 if (GET_CODE (b_head) == CODE_LABEL)
2374 /* Detect basic blocks with nothing but a label. This can happen
2375 in particular at the end of a function. */
2376 if (b_head == b_end)
2378 del_first = del_last = b_head;
2379 b_head = NEXT_INSN (b_head);
2382 /* Delete the basic block note. */
2383 if (NOTE_INSN_BASIC_BLOCK_P (b_head))
2385 if (b_head == b_end)
2390 b_head = NEXT_INSN (b_head);
2393 /* If there was a jump out of A, delete it. */
2395 if (GET_CODE (a_end) == JUMP_INSN)
2399 for (prev = PREV_INSN (a_end); ; prev = PREV_INSN (prev))
2400 if (GET_CODE (prev) != NOTE
2401 || NOTE_LINE_NUMBER (prev) == NOTE_INSN_BASIC_BLOCK
2408 /* If this was a conditional jump, we need to also delete
2409 the insn that set cc0. */
2410 if (prev && sets_cc0_p (prev))
2413 prev = prev_nonnote_insn (prev);
2422 else if (GET_CODE (NEXT_INSN (a_end)) == BARRIER)
2423 del_first = NEXT_INSN (a_end);
2425 /* Delete everything marked above as well as crap that might be
2426 hanging out between the two blocks. */
2427 flow_delete_insn_chain (del_first, del_last);
2429 /* Normally there should only be one successor of A and that is B, but
2430 partway though the merge of blocks for conditional_execution we'll
2431 be merging a TEST block with THEN and ELSE successors. Free the
2432 whole lot of them and hope the caller knows what they're doing. */
2434 remove_edge (a->succ);
2436 /* Adjust the edges out of B for the new owner. */
2437 for (e = b->succ; e; e = e->succ_next)
2441 /* B hasn't quite yet ceased to exist. Attempt to prevent mishap. */
2442 b->pred = b->succ = NULL;
2444 /* Reassociate the insns of B with A. */
2447 if (basic_block_for_insn)
2449 BLOCK_FOR_INSN (b_head) = a;
2450 while (b_head != b_end)
2452 b_head = NEXT_INSN (b_head);
2453 BLOCK_FOR_INSN (b_head) = a;
2463 /* Blocks A and B are to be merged into a single block. A has no incoming
2464 fallthru edge, so it can be moved before B without adding or modifying
2465 any jumps (aside from the jump from A to B). */
2468 merge_blocks_move_predecessor_nojumps (a, b)
2471 rtx start, end, barrier;
2477 barrier = next_nonnote_insn (end);
2478 if (GET_CODE (barrier) != BARRIER)
2480 flow_delete_insn (barrier);
2482 /* Move block and loop notes out of the chain so that we do not
2483 disturb their order.
2485 ??? A better solution would be to squeeze out all the non-nested notes
2486 and adjust the block trees appropriately. Even better would be to have
2487 a tighter connection between block trees and rtl so that this is not
2489 start = squeeze_notes (start, end);
2491 /* Scramble the insn chain. */
2492 if (end != PREV_INSN (b->head))
2493 reorder_insns (start, end, PREV_INSN (b->head));
2497 fprintf (rtl_dump_file, "Moved block %d before %d and merged.\n",
2498 a->index, b->index);
2501 /* Swap the records for the two blocks around. Although we are deleting B,
2502 A is now where B was and we want to compact the BB array from where
2504 BASIC_BLOCK (a->index) = b;
2505 BASIC_BLOCK (b->index) = a;
2507 a->index = b->index;
2510 /* Now blocks A and B are contiguous. Merge them. */
2511 merge_blocks_nomove (a, b);
2516 /* Blocks A and B are to be merged into a single block. B has no outgoing
2517 fallthru edge, so it can be moved after A without adding or modifying
2518 any jumps (aside from the jump from A to B). */
2521 merge_blocks_move_successor_nojumps (a, b)
2524 rtx start, end, barrier;
2528 barrier = NEXT_INSN (end);
2530 /* Recognize a jump table following block B. */
2531 if (GET_CODE (barrier) == CODE_LABEL
2532 && NEXT_INSN (barrier)
2533 && GET_CODE (NEXT_INSN (barrier)) == JUMP_INSN
2534 && (GET_CODE (PATTERN (NEXT_INSN (barrier))) == ADDR_VEC
2535 || GET_CODE (PATTERN (NEXT_INSN (barrier))) == ADDR_DIFF_VEC))
2537 end = NEXT_INSN (barrier);
2538 barrier = NEXT_INSN (end);
2541 /* There had better have been a barrier there. Delete it. */
2542 if (GET_CODE (barrier) != BARRIER)
2544 flow_delete_insn (barrier);
2546 /* Move block and loop notes out of the chain so that we do not
2547 disturb their order.
2549 ??? A better solution would be to squeeze out all the non-nested notes
2550 and adjust the block trees appropriately. Even better would be to have
2551 a tighter connection between block trees and rtl so that this is not
2553 start = squeeze_notes (start, end);
2555 /* Scramble the insn chain. */
2556 reorder_insns (start, end, a->end);
2558 /* Now blocks A and B are contiguous. Merge them. */
2559 merge_blocks_nomove (a, b);
2563 fprintf (rtl_dump_file, "Moved block %d after %d and merged.\n",
2564 b->index, a->index);
2570 /* Attempt to merge basic blocks that are potentially non-adjacent.
2571 Return true iff the attempt succeeded. */
2574 merge_blocks (e, b, c)
2578 /* If C has a tail recursion label, do not merge. There is no
2579 edge recorded from the call_placeholder back to this label, as
2580 that would make optimize_sibling_and_tail_recursive_calls more
2581 complex for no gain. */
2582 if (GET_CODE (c->head) == CODE_LABEL
2583 && tail_recursion_label_p (c->head))
2586 /* If B has a fallthru edge to C, no need to move anything. */
2587 if (e->flags & EDGE_FALLTHRU)
2589 merge_blocks_nomove (b, c);
2593 fprintf (rtl_dump_file, "Merged %d and %d without moving.\n",
2594 b->index, c->index);
2602 int c_has_outgoing_fallthru;
2603 int b_has_incoming_fallthru;
2605 /* We must make sure to not munge nesting of exception regions,
2606 lexical blocks, and loop notes.
2608 The first is taken care of by requiring that the active eh
2609 region at the end of one block always matches the active eh
2610 region at the beginning of the next block.
2612 The later two are taken care of by squeezing out all the notes. */
2614 /* ??? A throw/catch edge (or any abnormal edge) should be rarely
2615 executed and we may want to treat blocks which have two out
2616 edges, one normal, one abnormal as only having one edge for
2617 block merging purposes. */
2619 for (tmp_edge = c->succ; tmp_edge; tmp_edge = tmp_edge->succ_next)
2620 if (tmp_edge->flags & EDGE_FALLTHRU)
2622 c_has_outgoing_fallthru = (tmp_edge != NULL);
2624 for (tmp_edge = b->pred; tmp_edge; tmp_edge = tmp_edge->pred_next)
2625 if (tmp_edge->flags & EDGE_FALLTHRU)
2627 b_has_incoming_fallthru = (tmp_edge != NULL);
2629 /* If B does not have an incoming fallthru, then it can be moved
2630 immediately before C without introducing or modifying jumps.
2631 C cannot be the first block, so we do not have to worry about
2632 accessing a non-existent block. */
2633 if (! b_has_incoming_fallthru)
2634 return merge_blocks_move_predecessor_nojumps (b, c);
2636 /* Otherwise, we're going to try to move C after B. If C does
2637 not have an outgoing fallthru, then it can be moved
2638 immediately after B without introducing or modifying jumps. */
2639 if (! c_has_outgoing_fallthru)
2640 return merge_blocks_move_successor_nojumps (b, c);
2642 /* Otherwise, we'll need to insert an extra jump, and possibly
2643 a new block to contain it. */
2644 /* ??? Not implemented yet. */
2650 /* Top level driver for merge_blocks. */
2657 /* Attempt to merge blocks as made possible by edge removal. If a block
2658 has only one successor, and the successor has only one predecessor,
2659 they may be combined. */
2661 for (i = 0; i < n_basic_blocks;)
2663 basic_block c, b = BASIC_BLOCK (i);
2666 /* A loop because chains of blocks might be combineable. */
2667 while ((s = b->succ) != NULL
2668 && s->succ_next == NULL
2669 && (s->flags & EDGE_EH) == 0
2670 && (c = s->dest) != EXIT_BLOCK_PTR
2671 && c->pred->pred_next == NULL
2672 /* If the jump insn has side effects, we can't kill the edge. */
2673 && (GET_CODE (b->end) != JUMP_INSN
2674 || onlyjump_p (b->end))
2675 && merge_blocks (s, b, c))
2678 /* Don't get confused by the index shift caused by deleting blocks. */
2683 /* The given edge should potentially be a fallthru edge. If that is in
2684 fact true, delete the jump and barriers that are in the way. */
2687 tidy_fallthru_edge (e, b, c)
2693 /* ??? In a late-running flow pass, other folks may have deleted basic
2694 blocks by nopping out blocks, leaving multiple BARRIERs between here
2695 and the target label. They ought to be chastized and fixed.
2697 We can also wind up with a sequence of undeletable labels between
2698 one block and the next.
2700 So search through a sequence of barriers, labels, and notes for
2701 the head of block C and assert that we really do fall through. */
2703 if (next_real_insn (b->end) != next_real_insn (PREV_INSN (c->head)))
2706 /* Remove what will soon cease being the jump insn from the source block.
2707 If block B consisted only of this single jump, turn it into a deleted
2710 if (GET_CODE (q) == JUMP_INSN
2712 && (any_uncondjump_p (q)
2713 || (b->succ == e && e->succ_next == NULL)))
2716 /* If this was a conditional jump, we need to also delete
2717 the insn that set cc0. */
2718 if (any_condjump_p (q) && sets_cc0_p (PREV_INSN (q)))
2725 NOTE_LINE_NUMBER (q) = NOTE_INSN_DELETED;
2726 NOTE_SOURCE_FILE (q) = 0;
2732 /* We don't want a block to end on a line-number note since that has
2733 the potential of changing the code between -g and not -g. */
2734 while (GET_CODE (q) == NOTE && NOTE_LINE_NUMBER (q) >= 0)
2741 /* Selectively unlink the sequence. */
2742 if (q != PREV_INSN (c->head))
2743 flow_delete_insn_chain (NEXT_INSN (q), PREV_INSN (c->head));
2745 e->flags |= EDGE_FALLTHRU;
2748 /* Fix up edges that now fall through, or rather should now fall through
2749 but previously required a jump around now deleted blocks. Simplify
2750 the search by only examining blocks numerically adjacent, since this
2751 is how find_basic_blocks created them. */
2754 tidy_fallthru_edges ()
2758 for (i = 1; i < n_basic_blocks; ++i)
2760 basic_block b = BASIC_BLOCK (i - 1);
2761 basic_block c = BASIC_BLOCK (i);
2764 /* We care about simple conditional or unconditional jumps with
2767 If we had a conditional branch to the next instruction when
2768 find_basic_blocks was called, then there will only be one
2769 out edge for the block which ended with the conditional
2770 branch (since we do not create duplicate edges).
2772 Furthermore, the edge will be marked as a fallthru because we
2773 merge the flags for the duplicate edges. So we do not want to
2774 check that the edge is not a FALLTHRU edge. */
2775 if ((s = b->succ) != NULL
2776 && ! (s->flags & EDGE_COMPLEX)
2777 && s->succ_next == NULL
2779 /* If the jump insn has side effects, we can't tidy the edge. */
2780 && (GET_CODE (b->end) != JUMP_INSN
2781 || onlyjump_p (b->end)))
2782 tidy_fallthru_edge (s, b, c);
2786 /* Perform data flow analysis.
2787 F is the first insn of the function; FLAGS is a set of PROP_* flags
2788 to be used in accumulating flow info. */
2791 life_analysis (f, file, flags)
2796 #ifdef ELIMINABLE_REGS
2798 static struct {int from, to; } eliminables[] = ELIMINABLE_REGS;
2801 /* Record which registers will be eliminated. We use this in
2804 CLEAR_HARD_REG_SET (elim_reg_set);
2806 #ifdef ELIMINABLE_REGS
2807 for (i = 0; i < (int) ARRAY_SIZE (eliminables); i++)
2808 SET_HARD_REG_BIT (elim_reg_set, eliminables[i].from);
2810 SET_HARD_REG_BIT (elim_reg_set, FRAME_POINTER_REGNUM);
2814 flags &= ~(PROP_LOG_LINKS | PROP_AUTOINC);
2816 /* The post-reload life analysis have (on a global basis) the same
2817 registers live as was computed by reload itself. elimination
2818 Otherwise offsets and such may be incorrect.
2820 Reload will make some registers as live even though they do not
2823 We don't want to create new auto-incs after reload, since they
2824 are unlikely to be useful and can cause problems with shared
2826 if (reload_completed)
2827 flags &= ~(PROP_REG_INFO | PROP_AUTOINC);
2829 /* We want alias analysis information for local dead store elimination. */
2830 if (optimize && (flags & PROP_SCAN_DEAD_CODE))
2831 init_alias_analysis ();
2833 /* Always remove no-op moves. Do this before other processing so
2834 that we don't have to keep re-scanning them. */
2835 delete_noop_moves (f);
2837 /* Some targets can emit simpler epilogues if they know that sp was
2838 not ever modified during the function. After reload, of course,
2839 we've already emitted the epilogue so there's no sense searching. */
2840 if (! reload_completed)
2841 notice_stack_pointer_modification (f);
2843 /* Allocate and zero out data structures that will record the
2844 data from lifetime analysis. */
2845 allocate_reg_life_data ();
2846 allocate_bb_life_data ();
2848 /* Find the set of registers live on function exit. */
2849 mark_regs_live_at_end (EXIT_BLOCK_PTR->global_live_at_start);
2851 /* "Update" life info from zero. It'd be nice to begin the
2852 relaxation with just the exit and noreturn blocks, but that set
2853 is not immediately handy. */
2855 if (flags & PROP_REG_INFO)
2856 memset (regs_ever_live, 0, sizeof (regs_ever_live));
2857 update_life_info (NULL, UPDATE_LIFE_GLOBAL, flags);
2860 if (optimize && (flags & PROP_SCAN_DEAD_CODE))
2861 end_alias_analysis ();
2864 dump_flow_info (file);
2866 free_basic_block_vars (1);
2868 #ifdef ENABLE_CHECKING
2872 /* Search for any REG_LABEL notes which reference deleted labels. */
2873 for (insn = get_insns (); insn; insn = NEXT_INSN (insn))
2875 rtx inote = find_reg_note (insn, REG_LABEL, NULL_RTX);
2877 if (inote && GET_CODE (inote) == NOTE_INSN_DELETED_LABEL)
2884 /* A subroutine of verify_wide_reg, called through for_each_rtx.
2885 Search for REGNO. If found, abort if it is not wider than word_mode. */
2888 verify_wide_reg_1 (px, pregno)
2893 unsigned int regno = *(int *) pregno;
2895 if (GET_CODE (x) == REG && REGNO (x) == regno)
2897 if (GET_MODE_BITSIZE (GET_MODE (x)) <= BITS_PER_WORD)
2904 /* A subroutine of verify_local_live_at_start. Search through insns
2905 between HEAD and END looking for register REGNO. */
2908 verify_wide_reg (regno, head, end)
2915 && for_each_rtx (&PATTERN (head), verify_wide_reg_1, ®no))
2919 head = NEXT_INSN (head);
2922 /* We didn't find the register at all. Something's way screwy. */
2924 fprintf (rtl_dump_file, "Aborting in verify_wide_reg; reg %d\n", regno);
2925 print_rtl_and_abort ();
2928 /* A subroutine of update_life_info. Verify that there are no untoward
2929 changes in live_at_start during a local update. */
2932 verify_local_live_at_start (new_live_at_start, bb)
2933 regset new_live_at_start;
2936 if (reload_completed)
2938 /* After reload, there are no pseudos, nor subregs of multi-word
2939 registers. The regsets should exactly match. */
2940 if (! REG_SET_EQUAL_P (new_live_at_start, bb->global_live_at_start))
2944 fprintf (rtl_dump_file,
2945 "live_at_start mismatch in bb %d, aborting\n",
2947 debug_bitmap_file (rtl_dump_file, bb->global_live_at_start);
2948 debug_bitmap_file (rtl_dump_file, new_live_at_start);
2950 print_rtl_and_abort ();
2957 /* Find the set of changed registers. */
2958 XOR_REG_SET (new_live_at_start, bb->global_live_at_start);
2960 EXECUTE_IF_SET_IN_REG_SET (new_live_at_start, 0, i,
2962 /* No registers should die. */
2963 if (REGNO_REG_SET_P (bb->global_live_at_start, i))
2966 fprintf (rtl_dump_file,
2967 "Register %d died unexpectedly in block %d\n", i,
2969 print_rtl_and_abort ();
2972 /* Verify that the now-live register is wider than word_mode. */
2973 verify_wide_reg (i, bb->head, bb->end);
2978 /* Updates life information starting with the basic blocks set in BLOCKS.
2979 If BLOCKS is null, consider it to be the universal set.
2981 If EXTENT is UPDATE_LIFE_LOCAL, such as after splitting or peepholeing,
2982 we are only expecting local modifications to basic blocks. If we find
2983 extra registers live at the beginning of a block, then we either killed
2984 useful data, or we have a broken split that wants data not provided.
2985 If we find registers removed from live_at_start, that means we have
2986 a broken peephole that is killing a register it shouldn't.
2988 ??? This is not true in one situation -- when a pre-reload splitter
2989 generates subregs of a multi-word pseudo, current life analysis will
2990 lose the kill. So we _can_ have a pseudo go live. How irritating.
2992 Including PROP_REG_INFO does not properly refresh regs_ever_live
2993 unless the caller resets it to zero. */
2996 update_life_info (blocks, extent, prop_flags)
2998 enum update_life_extent extent;
3002 regset_head tmp_head;
3005 tmp = INITIALIZE_REG_SET (tmp_head);
3007 /* For a global update, we go through the relaxation process again. */
3008 if (extent != UPDATE_LIFE_LOCAL)
3010 calculate_global_regs_live (blocks, blocks,
3011 prop_flags & PROP_SCAN_DEAD_CODE);
3013 /* If asked, remove notes from the blocks we'll update. */
3014 if (extent == UPDATE_LIFE_GLOBAL_RM_NOTES)
3015 count_or_remove_death_notes (blocks, 1);
3020 EXECUTE_IF_SET_IN_SBITMAP (blocks, 0, i,
3022 basic_block bb = BASIC_BLOCK (i);
3024 COPY_REG_SET (tmp, bb->global_live_at_end);
3025 propagate_block (bb, tmp, NULL, NULL, prop_flags);
3027 if (extent == UPDATE_LIFE_LOCAL)
3028 verify_local_live_at_start (tmp, bb);
3033 for (i = n_basic_blocks - 1; i >= 0; --i)
3035 basic_block bb = BASIC_BLOCK (i);
3037 COPY_REG_SET (tmp, bb->global_live_at_end);
3038 propagate_block (bb, tmp, NULL, NULL, prop_flags);
3040 if (extent == UPDATE_LIFE_LOCAL)
3041 verify_local_live_at_start (tmp, bb);
3047 if (prop_flags & PROP_REG_INFO)
3049 /* The only pseudos that are live at the beginning of the function
3050 are those that were not set anywhere in the function. local-alloc
3051 doesn't know how to handle these correctly, so mark them as not
3052 local to any one basic block. */
3053 EXECUTE_IF_SET_IN_REG_SET (ENTRY_BLOCK_PTR->global_live_at_end,
3054 FIRST_PSEUDO_REGISTER, i,
3055 { REG_BASIC_BLOCK (i) = REG_BLOCK_GLOBAL; });
3057 /* We have a problem with any pseudoreg that lives across the setjmp.
3058 ANSI says that if a user variable does not change in value between
3059 the setjmp and the longjmp, then the longjmp preserves it. This
3060 includes longjmp from a place where the pseudo appears dead.
3061 (In principle, the value still exists if it is in scope.)
3062 If the pseudo goes in a hard reg, some other value may occupy
3063 that hard reg where this pseudo is dead, thus clobbering the pseudo.
3064 Conclusion: such a pseudo must not go in a hard reg. */
3065 EXECUTE_IF_SET_IN_REG_SET (regs_live_at_setjmp,
3066 FIRST_PSEUDO_REGISTER, i,
3068 if (regno_reg_rtx[i] != 0)
3070 REG_LIVE_LENGTH (i) = -1;
3071 REG_BASIC_BLOCK (i) = REG_BLOCK_UNKNOWN;
3077 /* Free the variables allocated by find_basic_blocks.
3079 KEEP_HEAD_END_P is non-zero if basic_block_info is not to be freed. */
3082 free_basic_block_vars (keep_head_end_p)
3083 int keep_head_end_p;
3085 if (basic_block_for_insn)
3087 VARRAY_FREE (basic_block_for_insn);
3088 basic_block_for_insn = NULL;
3091 if (! keep_head_end_p)
3094 VARRAY_FREE (basic_block_info);
3097 ENTRY_BLOCK_PTR->aux = NULL;
3098 ENTRY_BLOCK_PTR->global_live_at_end = NULL;
3099 EXIT_BLOCK_PTR->aux = NULL;
3100 EXIT_BLOCK_PTR->global_live_at_start = NULL;
3104 /* Return nonzero if an insn consists only of SETs, each of which only sets a
3111 rtx pat = PATTERN (insn);
3113 /* Insns carrying these notes are useful later on. */
3114 if (find_reg_note (insn, REG_EQUAL, NULL_RTX))
3117 if (GET_CODE (pat) == SET && set_noop_p (pat))
3120 if (GET_CODE (pat) == PARALLEL)
3123 /* If nothing but SETs of registers to themselves,
3124 this insn can also be deleted. */
3125 for (i = 0; i < XVECLEN (pat, 0); i++)
3127 rtx tem = XVECEXP (pat, 0, i);
3129 if (GET_CODE (tem) == USE
3130 || GET_CODE (tem) == CLOBBER)
3133 if (GET_CODE (tem) != SET || ! set_noop_p (tem))
3142 /* Delete any insns that copy a register to itself. */
3145 delete_noop_moves (f)
3149 for (insn = f; insn; insn = NEXT_INSN (insn))
3151 if (GET_CODE (insn) == INSN && noop_move_p (insn))
3153 PUT_CODE (insn, NOTE);
3154 NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED;
3155 NOTE_SOURCE_FILE (insn) = 0;
3160 /* Determine if the stack pointer is constant over the life of the function.
3161 Only useful before prologues have been emitted. */
3164 notice_stack_pointer_modification_1 (x, pat, data)
3166 rtx pat ATTRIBUTE_UNUSED;
3167 void *data ATTRIBUTE_UNUSED;
3169 if (x == stack_pointer_rtx
3170 /* The stack pointer is only modified indirectly as the result
3171 of a push until later in flow. See the comments in rtl.texi
3172 regarding Embedded Side-Effects on Addresses. */
3173 || (GET_CODE (x) == MEM
3174 && GET_RTX_CLASS (GET_CODE (XEXP (x, 0))) == 'a'
3175 && XEXP (XEXP (x, 0), 0) == stack_pointer_rtx))
3176 current_function_sp_is_unchanging = 0;
3180 notice_stack_pointer_modification (f)
3185 /* Assume that the stack pointer is unchanging if alloca hasn't
3187 current_function_sp_is_unchanging = !current_function_calls_alloca;
3188 if (! current_function_sp_is_unchanging)
3191 for (insn = f; insn; insn = NEXT_INSN (insn))
3195 /* Check if insn modifies the stack pointer. */
3196 note_stores (PATTERN (insn), notice_stack_pointer_modification_1,
3198 if (! current_function_sp_is_unchanging)
3204 /* Mark a register in SET. Hard registers in large modes get all
3205 of their component registers set as well. */
3208 mark_reg (reg, xset)
3212 regset set = (regset) xset;
3213 int regno = REGNO (reg);
3215 if (GET_MODE (reg) == BLKmode)
3218 SET_REGNO_REG_SET (set, regno);
3219 if (regno < FIRST_PSEUDO_REGISTER)
3221 int n = HARD_REGNO_NREGS (regno, GET_MODE (reg));
3223 SET_REGNO_REG_SET (set, regno + n);
3227 /* Mark those regs which are needed at the end of the function as live
3228 at the end of the last basic block. */
3231 mark_regs_live_at_end (set)
3236 /* If exiting needs the right stack value, consider the stack pointer
3237 live at the end of the function. */
3238 if ((HAVE_epilogue && reload_completed)
3239 || ! EXIT_IGNORE_STACK
3240 || (! FRAME_POINTER_REQUIRED
3241 && ! current_function_calls_alloca
3242 && flag_omit_frame_pointer)
3243 || current_function_sp_is_unchanging)
3245 SET_REGNO_REG_SET (set, STACK_POINTER_REGNUM);
3248 /* Mark the frame pointer if needed at the end of the function. If
3249 we end up eliminating it, it will be removed from the live list
3250 of each basic block by reload. */
3252 if (! reload_completed || frame_pointer_needed)
3254 SET_REGNO_REG_SET (set, FRAME_POINTER_REGNUM);
3255 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
3256 /* If they are different, also mark the hard frame pointer as live. */
3257 if (! LOCAL_REGNO (HARD_FRAME_POINTER_REGNUM))
3258 SET_REGNO_REG_SET (set, HARD_FRAME_POINTER_REGNUM);
3262 #ifndef PIC_OFFSET_TABLE_REG_CALL_CLOBBERED
3263 /* Many architectures have a GP register even without flag_pic.
3264 Assume the pic register is not in use, or will be handled by
3265 other means, if it is not fixed. */
3266 if (PIC_OFFSET_TABLE_REGNUM != INVALID_REGNUM
3267 && fixed_regs[PIC_OFFSET_TABLE_REGNUM])
3268 SET_REGNO_REG_SET (set, PIC_OFFSET_TABLE_REGNUM);
3271 /* Mark all global registers, and all registers used by the epilogue
3272 as being live at the end of the function since they may be
3273 referenced by our caller. */
3274 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
3275 if (global_regs[i] || EPILOGUE_USES (i))
3276 SET_REGNO_REG_SET (set, i);
3278 if (HAVE_epilogue && reload_completed)
3280 /* Mark all call-saved registers that we actually used. */
3281 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
3282 if (regs_ever_live[i] && ! call_used_regs[i] && ! LOCAL_REGNO (i))
3283 SET_REGNO_REG_SET (set, i);
3286 #ifdef EH_RETURN_DATA_REGNO
3287 /* Mark the registers that will contain data for the handler. */
3288 if (reload_completed && current_function_calls_eh_return)
3291 unsigned regno = EH_RETURN_DATA_REGNO(i);
3292 if (regno == INVALID_REGNUM)
3294 SET_REGNO_REG_SET (set, regno);
3297 #ifdef EH_RETURN_STACKADJ_RTX
3298 if ((! HAVE_epilogue || ! reload_completed)
3299 && current_function_calls_eh_return)
3301 rtx tmp = EH_RETURN_STACKADJ_RTX;
3302 if (tmp && REG_P (tmp))
3303 mark_reg (tmp, set);
3306 #ifdef EH_RETURN_HANDLER_RTX
3307 if ((! HAVE_epilogue || ! reload_completed)
3308 && current_function_calls_eh_return)
3310 rtx tmp = EH_RETURN_HANDLER_RTX;
3311 if (tmp && REG_P (tmp))
3312 mark_reg (tmp, set);
3316 /* Mark function return value. */
3317 diddle_return_value (mark_reg, set);
3320 /* Callback function for for_each_successor_phi. DATA is a regset.
3321 Sets the SRC_REGNO, the regno of the phi alternative for phi node
3322 INSN, in the regset. */
3325 set_phi_alternative_reg (insn, dest_regno, src_regno, data)
3326 rtx insn ATTRIBUTE_UNUSED;
3327 int dest_regno ATTRIBUTE_UNUSED;
3331 regset live = (regset) data;
3332 SET_REGNO_REG_SET (live, src_regno);
3336 /* Propagate global life info around the graph of basic blocks. Begin
3337 considering blocks with their corresponding bit set in BLOCKS_IN.
3338 If BLOCKS_IN is null, consider it the universal set.
3340 BLOCKS_OUT is set for every block that was changed. */
3343 calculate_global_regs_live (blocks_in, blocks_out, flags)
3344 sbitmap blocks_in, blocks_out;
3347 basic_block *queue, *qhead, *qtail, *qend;
3348 regset tmp, new_live_at_end, call_used;
3349 regset_head tmp_head, call_used_head;
3350 regset_head new_live_at_end_head;
3353 tmp = INITIALIZE_REG_SET (tmp_head);
3354 new_live_at_end = INITIALIZE_REG_SET (new_live_at_end_head);
3355 call_used = INITIALIZE_REG_SET (call_used_head);
3357 /* Inconveniently, this is only redily available in hard reg set form. */
3358 for (i = 0; i < FIRST_PSEUDO_REGISTER; ++i)
3359 if (call_used_regs[i])
3360 SET_REGNO_REG_SET (call_used, i);
3362 /* Create a worklist. Allocate an extra slot for ENTRY_BLOCK, and one
3363 because the `head == tail' style test for an empty queue doesn't
3364 work with a full queue. */
3365 queue = (basic_block *) xmalloc ((n_basic_blocks + 2) * sizeof (*queue));
3367 qhead = qend = queue + n_basic_blocks + 2;
3369 /* Queue the blocks set in the initial mask. Do this in reverse block
3370 number order so that we are more likely for the first round to do
3371 useful work. We use AUX non-null to flag that the block is queued. */
3374 /* Clear out the garbage that might be hanging out in bb->aux. */
3375 for (i = n_basic_blocks - 1; i >= 0; --i)
3376 BASIC_BLOCK (i)->aux = NULL;
3378 EXECUTE_IF_SET_IN_SBITMAP (blocks_in, 0, i,
3380 basic_block bb = BASIC_BLOCK (i);
3387 for (i = 0; i < n_basic_blocks; ++i)
3389 basic_block bb = BASIC_BLOCK (i);
3396 sbitmap_zero (blocks_out);
3398 /* We work through the queue until there are no more blocks. What
3399 is live at the end of this block is precisely the union of what
3400 is live at the beginning of all its successors. So, we set its
3401 GLOBAL_LIVE_AT_END field based on the GLOBAL_LIVE_AT_START field
3402 for its successors. Then, we compute GLOBAL_LIVE_AT_START for
3403 this block by walking through the instructions in this block in
3404 reverse order and updating as we go. If that changed
3405 GLOBAL_LIVE_AT_START, we add the predecessors of the block to the
3406 queue; they will now need to recalculate GLOBAL_LIVE_AT_END.
3408 We are guaranteed to terminate, because GLOBAL_LIVE_AT_START
3409 never shrinks. If a register appears in GLOBAL_LIVE_AT_START, it
3410 must either be live at the end of the block, or used within the
3411 block. In the latter case, it will certainly never disappear
3412 from GLOBAL_LIVE_AT_START. In the former case, the register
3413 could go away only if it disappeared from GLOBAL_LIVE_AT_START
3414 for one of the successor blocks. By induction, that cannot
3416 while (qhead != qtail)
3418 int rescan, changed;
3427 /* Begin by propagating live_at_start from the successor blocks. */
3428 CLEAR_REG_SET (new_live_at_end);
3429 for (e = bb->succ; e; e = e->succ_next)
3431 basic_block sb = e->dest;
3433 /* Call-clobbered registers die across exception and call edges. */
3434 /* ??? Abnormal call edges ignored for the moment, as this gets
3435 confused by sibling call edges, which crashes reg-stack. */
3436 if (e->flags & EDGE_EH)
3438 bitmap_operation (tmp, sb->global_live_at_start,
3439 call_used, BITMAP_AND_COMPL);
3440 IOR_REG_SET (new_live_at_end, tmp);
3443 IOR_REG_SET (new_live_at_end, sb->global_live_at_start);
3446 /* The all-important stack pointer must always be live. */
3447 SET_REGNO_REG_SET (new_live_at_end, STACK_POINTER_REGNUM);
3449 /* Before reload, there are a few registers that must be forced
3450 live everywhere -- which might not already be the case for
3451 blocks within infinite loops. */
3452 if (! reload_completed)
3454 /* Any reference to any pseudo before reload is a potential
3455 reference of the frame pointer. */
3456 SET_REGNO_REG_SET (new_live_at_end, FRAME_POINTER_REGNUM);
3458 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
3459 /* Pseudos with argument area equivalences may require
3460 reloading via the argument pointer. */
3461 if (fixed_regs[ARG_POINTER_REGNUM])
3462 SET_REGNO_REG_SET (new_live_at_end, ARG_POINTER_REGNUM);
3465 /* Any constant, or pseudo with constant equivalences, may
3466 require reloading from memory using the pic register. */
3467 if (PIC_OFFSET_TABLE_REGNUM != INVALID_REGNUM
3468 && fixed_regs[PIC_OFFSET_TABLE_REGNUM])
3469 SET_REGNO_REG_SET (new_live_at_end, PIC_OFFSET_TABLE_REGNUM);
3472 /* Regs used in phi nodes are not included in
3473 global_live_at_start, since they are live only along a
3474 particular edge. Set those regs that are live because of a
3475 phi node alternative corresponding to this particular block. */
3477 for_each_successor_phi (bb, &set_phi_alternative_reg,
3480 if (bb == ENTRY_BLOCK_PTR)
3482 COPY_REG_SET (bb->global_live_at_end, new_live_at_end);
3486 /* On our first pass through this block, we'll go ahead and continue.
3487 Recognize first pass by local_set NULL. On subsequent passes, we
3488 get to skip out early if live_at_end wouldn't have changed. */
3490 if (bb->local_set == NULL)
3492 bb->local_set = OBSTACK_ALLOC_REG_SET (&flow_obstack);
3493 bb->cond_local_set = OBSTACK_ALLOC_REG_SET (&flow_obstack);
3498 /* If any bits were removed from live_at_end, we'll have to
3499 rescan the block. This wouldn't be necessary if we had
3500 precalculated local_live, however with PROP_SCAN_DEAD_CODE
3501 local_live is really dependent on live_at_end. */
3502 CLEAR_REG_SET (tmp);
3503 rescan = bitmap_operation (tmp, bb->global_live_at_end,
3504 new_live_at_end, BITMAP_AND_COMPL);
3508 /* If any of the registers in the new live_at_end set are
3509 conditionally set in this basic block, we must rescan.
3510 This is because conditional lifetimes at the end of the
3511 block do not just take the live_at_end set into account,
3512 but also the liveness at the start of each successor
3513 block. We can miss changes in those sets if we only
3514 compare the new live_at_end against the previous one. */
3515 CLEAR_REG_SET (tmp);
3516 rescan = bitmap_operation (tmp, new_live_at_end,
3517 bb->cond_local_set, BITMAP_AND);
3522 /* Find the set of changed bits. Take this opportunity
3523 to notice that this set is empty and early out. */
3524 CLEAR_REG_SET (tmp);
3525 changed = bitmap_operation (tmp, bb->global_live_at_end,
3526 new_live_at_end, BITMAP_XOR);
3530 /* If any of the changed bits overlap with local_set,
3531 we'll have to rescan the block. Detect overlap by
3532 the AND with ~local_set turning off bits. */
3533 rescan = bitmap_operation (tmp, tmp, bb->local_set,
3538 /* Let our caller know that BB changed enough to require its
3539 death notes updated. */
3541 SET_BIT (blocks_out, bb->index);
3545 /* Add to live_at_start the set of all registers in
3546 new_live_at_end that aren't in the old live_at_end. */
3548 bitmap_operation (tmp, new_live_at_end, bb->global_live_at_end,
3550 COPY_REG_SET (bb->global_live_at_end, new_live_at_end);
3552 changed = bitmap_operation (bb->global_live_at_start,
3553 bb->global_live_at_start,
3560 COPY_REG_SET (bb->global_live_at_end, new_live_at_end);
3562 /* Rescan the block insn by insn to turn (a copy of) live_at_end
3563 into live_at_start. */
3564 propagate_block (bb, new_live_at_end, bb->local_set,
3565 bb->cond_local_set, flags);
3567 /* If live_at start didn't change, no need to go farther. */
3568 if (REG_SET_EQUAL_P (bb->global_live_at_start, new_live_at_end))
3571 COPY_REG_SET (bb->global_live_at_start, new_live_at_end);
3574 /* Queue all predecessors of BB so that we may re-examine
3575 their live_at_end. */
3576 for (e = bb->pred; e; e = e->pred_next)
3578 basic_block pb = e->src;
3579 if (pb->aux == NULL)
3590 FREE_REG_SET (new_live_at_end);
3591 FREE_REG_SET (call_used);
3595 EXECUTE_IF_SET_IN_SBITMAP (blocks_out, 0, i,
3597 basic_block bb = BASIC_BLOCK (i);
3598 FREE_REG_SET (bb->local_set);
3599 FREE_REG_SET (bb->cond_local_set);
3604 for (i = n_basic_blocks - 1; i >= 0; --i)
3606 basic_block bb = BASIC_BLOCK (i);
3607 FREE_REG_SET (bb->local_set);
3608 FREE_REG_SET (bb->cond_local_set);
3615 /* Subroutines of life analysis. */
3617 /* Allocate the permanent data structures that represent the results
3618 of life analysis. Not static since used also for stupid life analysis. */
3621 allocate_bb_life_data ()
3625 for (i = 0; i < n_basic_blocks; i++)
3627 basic_block bb = BASIC_BLOCK (i);
3629 bb->global_live_at_start = OBSTACK_ALLOC_REG_SET (&flow_obstack);
3630 bb->global_live_at_end = OBSTACK_ALLOC_REG_SET (&flow_obstack);
3633 ENTRY_BLOCK_PTR->global_live_at_end
3634 = OBSTACK_ALLOC_REG_SET (&flow_obstack);
3635 EXIT_BLOCK_PTR->global_live_at_start
3636 = OBSTACK_ALLOC_REG_SET (&flow_obstack);
3638 regs_live_at_setjmp = OBSTACK_ALLOC_REG_SET (&flow_obstack);
3642 allocate_reg_life_data ()
3646 max_regno = max_reg_num ();
3648 /* Recalculate the register space, in case it has grown. Old style
3649 vector oriented regsets would set regset_{size,bytes} here also. */
3650 allocate_reg_info (max_regno, FALSE, FALSE);
3652 /* Reset all the data we'll collect in propagate_block and its
3654 for (i = 0; i < max_regno; i++)
3658 REG_N_DEATHS (i) = 0;
3659 REG_N_CALLS_CROSSED (i) = 0;
3660 REG_LIVE_LENGTH (i) = 0;
3661 REG_BASIC_BLOCK (i) = REG_BLOCK_UNKNOWN;
3665 /* Delete dead instructions for propagate_block. */
3668 propagate_block_delete_insn (bb, insn)
3672 rtx inote = find_reg_note (insn, REG_LABEL, NULL_RTX);
3674 /* If the insn referred to a label, and that label was attached to
3675 an ADDR_VEC, it's safe to delete the ADDR_VEC. In fact, it's
3676 pretty much mandatory to delete it, because the ADDR_VEC may be
3677 referencing labels that no longer exist.
3679 INSN may reference a deleted label, particularly when a jump
3680 table has been optimized into a direct jump. There's no
3681 real good way to fix up the reference to the deleted label
3682 when the label is deleted, so we just allow it here.
3684 After dead code elimination is complete, we do search for
3685 any REG_LABEL notes which reference deleted labels as a
3688 if (inote && GET_CODE (inote) == CODE_LABEL)
3690 rtx label = XEXP (inote, 0);
3693 /* The label may be forced if it has been put in the constant
3694 pool. If that is the only use we must discard the table
3695 jump following it, but not the label itself. */
3696 if (LABEL_NUSES (label) == 1 + LABEL_PRESERVE_P (label)
3697 && (next = next_nonnote_insn (label)) != NULL
3698 && GET_CODE (next) == JUMP_INSN
3699 && (GET_CODE (PATTERN (next)) == ADDR_VEC
3700 || GET_CODE (PATTERN (next)) == ADDR_DIFF_VEC))
3702 rtx pat = PATTERN (next);
3703 int diff_vec_p = GET_CODE (pat) == ADDR_DIFF_VEC;
3704 int len = XVECLEN (pat, diff_vec_p);
3707 for (i = 0; i < len; i++)
3708 LABEL_NUSES (XEXP (XVECEXP (pat, diff_vec_p, i), 0))--;
3710 flow_delete_insn (next);
3714 if (bb->end == insn)
3715 bb->end = PREV_INSN (insn);
3716 flow_delete_insn (insn);
3719 /* Delete dead libcalls for propagate_block. Return the insn
3720 before the libcall. */
3723 propagate_block_delete_libcall (bb, insn, note)
3727 rtx first = XEXP (note, 0);
3728 rtx before = PREV_INSN (first);
3730 if (insn == bb->end)
3733 flow_delete_insn_chain (first, insn);
3737 /* Update the life-status of regs for one insn. Return the previous insn. */
3740 propagate_one_insn (pbi, insn)
3741 struct propagate_block_info *pbi;
3744 rtx prev = PREV_INSN (insn);
3745 int flags = pbi->flags;
3746 int insn_is_dead = 0;
3747 int libcall_is_dead = 0;
3751 if (! INSN_P (insn))
3754 note = find_reg_note (insn, REG_RETVAL, NULL_RTX);
3755 if (flags & PROP_SCAN_DEAD_CODE)
3757 insn_is_dead = insn_dead_p (pbi, PATTERN (insn), 0, REG_NOTES (insn));
3758 libcall_is_dead = (insn_is_dead && note != 0
3759 && libcall_dead_p (pbi, note, insn));
3762 /* If an instruction consists of just dead store(s) on final pass,
3764 if ((flags & PROP_KILL_DEAD_CODE) && insn_is_dead)
3766 /* If we're trying to delete a prologue or epilogue instruction
3767 that isn't flagged as possibly being dead, something is wrong.
3768 But if we are keeping the stack pointer depressed, we might well
3769 be deleting insns that are used to compute the amount to update
3770 it by, so they are fine. */
3771 if (reload_completed
3772 && !(TREE_CODE (TREE_TYPE (current_function_decl)) == FUNCTION_TYPE
3773 && (TYPE_RETURNS_STACK_DEPRESSED
3774 (TREE_TYPE (current_function_decl))))
3775 && (((HAVE_epilogue || HAVE_prologue)
3776 && prologue_epilogue_contains (insn))
3777 || (HAVE_sibcall_epilogue
3778 && sibcall_epilogue_contains (insn)))
3779 && find_reg_note (insn, REG_MAYBE_DEAD, NULL_RTX) == 0)
3782 /* Record sets. Do this even for dead instructions, since they
3783 would have killed the values if they hadn't been deleted. */
3784 mark_set_regs (pbi, PATTERN (insn), insn);
3786 /* CC0 is now known to be dead. Either this insn used it,
3787 in which case it doesn't anymore, or clobbered it,
3788 so the next insn can't use it. */
3791 if (libcall_is_dead)
3792 prev = propagate_block_delete_libcall (pbi->bb, insn, note);
3794 propagate_block_delete_insn (pbi->bb, insn);
3799 /* See if this is an increment or decrement that can be merged into
3800 a following memory address. */
3803 register rtx x = single_set (insn);
3805 /* Does this instruction increment or decrement a register? */
3806 if ((flags & PROP_AUTOINC)
3808 && GET_CODE (SET_DEST (x)) == REG
3809 && (GET_CODE (SET_SRC (x)) == PLUS
3810 || GET_CODE (SET_SRC (x)) == MINUS)
3811 && XEXP (SET_SRC (x), 0) == SET_DEST (x)
3812 && GET_CODE (XEXP (SET_SRC (x), 1)) == CONST_INT
3813 /* Ok, look for a following memory ref we can combine with.
3814 If one is found, change the memory ref to a PRE_INC
3815 or PRE_DEC, cancel this insn, and return 1.
3816 Return 0 if nothing has been done. */
3817 && try_pre_increment_1 (pbi, insn))
3820 #endif /* AUTO_INC_DEC */
3822 CLEAR_REG_SET (pbi->new_set);
3824 /* If this is not the final pass, and this insn is copying the value of
3825 a library call and it's dead, don't scan the insns that perform the
3826 library call, so that the call's arguments are not marked live. */
3827 if (libcall_is_dead)
3829 /* Record the death of the dest reg. */
3830 mark_set_regs (pbi, PATTERN (insn), insn);
3832 insn = XEXP (note, 0);
3833 return PREV_INSN (insn);
3835 else if (GET_CODE (PATTERN (insn)) == SET
3836 && SET_DEST (PATTERN (insn)) == stack_pointer_rtx
3837 && GET_CODE (SET_SRC (PATTERN (insn))) == PLUS
3838 && XEXP (SET_SRC (PATTERN (insn)), 0) == stack_pointer_rtx
3839 && GET_CODE (XEXP (SET_SRC (PATTERN (insn)), 1)) == CONST_INT)
3840 /* We have an insn to pop a constant amount off the stack.
3841 (Such insns use PLUS regardless of the direction of the stack,
3842 and any insn to adjust the stack by a constant is always a pop.)
3843 These insns, if not dead stores, have no effect on life. */
3847 /* Any regs live at the time of a call instruction must not go
3848 in a register clobbered by calls. Find all regs now live and
3849 record this for them. */
3851 if (GET_CODE (insn) == CALL_INSN && (flags & PROP_REG_INFO))
3852 EXECUTE_IF_SET_IN_REG_SET (pbi->reg_live, 0, i,
3853 { REG_N_CALLS_CROSSED (i)++; });
3855 /* Record sets. Do this even for dead instructions, since they
3856 would have killed the values if they hadn't been deleted. */
3857 mark_set_regs (pbi, PATTERN (insn), insn);
3859 if (GET_CODE (insn) == CALL_INSN)
3865 if (GET_CODE (PATTERN (insn)) == COND_EXEC)
3866 cond = COND_EXEC_TEST (PATTERN (insn));
3868 /* Non-constant calls clobber memory. */
3869 if (! CONST_CALL_P (insn))
3871 free_EXPR_LIST_list (&pbi->mem_set_list);
3872 pbi->mem_set_list_len = 0;
3875 /* There may be extra registers to be clobbered. */
3876 for (note = CALL_INSN_FUNCTION_USAGE (insn);
3878 note = XEXP (note, 1))
3879 if (GET_CODE (XEXP (note, 0)) == CLOBBER)
3880 mark_set_1 (pbi, CLOBBER, XEXP (XEXP (note, 0), 0),
3881 cond, insn, pbi->flags);
3883 /* Calls change all call-used and global registers. */
3884 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
3885 if (call_used_regs[i] && ! global_regs[i]
3888 /* We do not want REG_UNUSED notes for these registers. */
3889 mark_set_1 (pbi, CLOBBER, gen_rtx_REG (reg_raw_mode[i], i),
3891 pbi->flags & ~(PROP_DEATH_NOTES | PROP_REG_INFO));
3895 /* If an insn doesn't use CC0, it becomes dead since we assume
3896 that every insn clobbers it. So show it dead here;
3897 mark_used_regs will set it live if it is referenced. */
3902 mark_used_regs (pbi, PATTERN (insn), NULL_RTX, insn);
3904 /* Sometimes we may have inserted something before INSN (such as a move)
3905 when we make an auto-inc. So ensure we will scan those insns. */
3907 prev = PREV_INSN (insn);
3910 if (! insn_is_dead && GET_CODE (insn) == CALL_INSN)
3916 if (GET_CODE (PATTERN (insn)) == COND_EXEC)
3917 cond = COND_EXEC_TEST (PATTERN (insn));
3919 /* Calls use their arguments. */
3920 for (note = CALL_INSN_FUNCTION_USAGE (insn);
3922 note = XEXP (note, 1))
3923 if (GET_CODE (XEXP (note, 0)) == USE)
3924 mark_used_regs (pbi, XEXP (XEXP (note, 0), 0),
3927 /* The stack ptr is used (honorarily) by a CALL insn. */
3928 SET_REGNO_REG_SET (pbi->reg_live, STACK_POINTER_REGNUM);
3930 /* Calls may also reference any of the global registers,
3931 so they are made live. */
3932 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
3934 mark_used_reg (pbi, gen_rtx_REG (reg_raw_mode[i], i),
3939 /* On final pass, update counts of how many insns in which each reg
3941 if (flags & PROP_REG_INFO)
3942 EXECUTE_IF_SET_IN_REG_SET (pbi->reg_live, 0, i,
3943 { REG_LIVE_LENGTH (i)++; });
3948 /* Initialize a propagate_block_info struct for public consumption.
3949 Note that the structure itself is opaque to this file, but that
3950 the user can use the regsets provided here. */
3952 struct propagate_block_info *
3953 init_propagate_block_info (bb, live, local_set, cond_local_set, flags)
3955 regset live, local_set, cond_local_set;
3958 struct propagate_block_info *pbi = xmalloc (sizeof (*pbi));
3961 pbi->reg_live = live;
3962 pbi->mem_set_list = NULL_RTX;
3963 pbi->mem_set_list_len = 0;
3964 pbi->local_set = local_set;
3965 pbi->cond_local_set = cond_local_set;
3969 if (flags & (PROP_LOG_LINKS | PROP_AUTOINC))
3970 pbi->reg_next_use = (rtx *) xcalloc (max_reg_num (), sizeof (rtx));
3972 pbi->reg_next_use = NULL;
3974 pbi->new_set = BITMAP_XMALLOC ();
3976 #ifdef HAVE_conditional_execution
3977 pbi->reg_cond_dead = splay_tree_new (splay_tree_compare_ints, NULL,
3978 free_reg_cond_life_info);
3979 pbi->reg_cond_reg = BITMAP_XMALLOC ();
3981 /* If this block ends in a conditional branch, for each register live
3982 from one side of the branch and not the other, record the register
3983 as conditionally dead. */
3984 if (GET_CODE (bb->end) == JUMP_INSN
3985 && any_condjump_p (bb->end))
3987 regset_head diff_head;
3988 regset diff = INITIALIZE_REG_SET (diff_head);
3989 basic_block bb_true, bb_false;
3990 rtx cond_true, cond_false, set_src;
3993 /* Identify the successor blocks. */
3994 bb_true = bb->succ->dest;
3995 if (bb->succ->succ_next != NULL)
3997 bb_false = bb->succ->succ_next->dest;
3999 if (bb->succ->flags & EDGE_FALLTHRU)
4001 basic_block t = bb_false;
4005 else if (! (bb->succ->succ_next->flags & EDGE_FALLTHRU))
4010 /* This can happen with a conditional jump to the next insn. */
4011 if (JUMP_LABEL (bb->end) != bb_true->head)
4014 /* Simplest way to do nothing. */
4018 /* Extract the condition from the branch. */
4019 set_src = SET_SRC (pc_set (bb->end));
4020 cond_true = XEXP (set_src, 0);
4021 cond_false = gen_rtx_fmt_ee (reverse_condition (GET_CODE (cond_true)),
4022 GET_MODE (cond_true), XEXP (cond_true, 0),
4023 XEXP (cond_true, 1));
4024 if (GET_CODE (XEXP (set_src, 1)) == PC)
4027 cond_false = cond_true;
4031 /* Compute which register lead different lives in the successors. */
4032 if (bitmap_operation (diff, bb_true->global_live_at_start,
4033 bb_false->global_live_at_start, BITMAP_XOR))
4035 rtx reg = XEXP (cond_true, 0);
4037 if (GET_CODE (reg) == SUBREG)
4038 reg = SUBREG_REG (reg);
4040 if (GET_CODE (reg) != REG)
4043 SET_REGNO_REG_SET (pbi->reg_cond_reg, REGNO (reg));
4045 /* For each such register, mark it conditionally dead. */
4046 EXECUTE_IF_SET_IN_REG_SET
4049 struct reg_cond_life_info *rcli;
4052 rcli = (struct reg_cond_life_info *) xmalloc (sizeof (*rcli));
4054 if (REGNO_REG_SET_P (bb_true->global_live_at_start, i))
4058 rcli->condition = cond;
4059 rcli->stores = const0_rtx;
4060 rcli->orig_condition = cond;
4062 splay_tree_insert (pbi->reg_cond_dead, i,
4063 (splay_tree_value) rcli);
4067 FREE_REG_SET (diff);
4071 /* If this block has no successors, any stores to the frame that aren't
4072 used later in the block are dead. So make a pass over the block
4073 recording any such that are made and show them dead at the end. We do
4074 a very conservative and simple job here. */
4076 && ! (TREE_CODE (TREE_TYPE (current_function_decl)) == FUNCTION_TYPE
4077 && (TYPE_RETURNS_STACK_DEPRESSED
4078 (TREE_TYPE (current_function_decl))))
4079 && (flags & PROP_SCAN_DEAD_CODE)
4080 && (bb->succ == NULL
4081 || (bb->succ->succ_next == NULL
4082 && bb->succ->dest == EXIT_BLOCK_PTR
4083 && ! current_function_calls_eh_return)))
4086 for (insn = bb->end; insn != bb->head; insn = PREV_INSN (insn))
4087 if (GET_CODE (insn) == INSN
4088 && (set = single_set (insn))
4089 && GET_CODE (SET_DEST (set)) == MEM)
4091 rtx mem = SET_DEST (set);
4092 rtx canon_mem = canon_rtx (mem);
4094 /* This optimization is performed by faking a store to the
4095 memory at the end of the block. This doesn't work for
4096 unchanging memories because multiple stores to unchanging
4097 memory is illegal and alias analysis doesn't consider it. */
4098 if (RTX_UNCHANGING_P (canon_mem))
4101 if (XEXP (canon_mem, 0) == frame_pointer_rtx
4102 || (GET_CODE (XEXP (canon_mem, 0)) == PLUS
4103 && XEXP (XEXP (canon_mem, 0), 0) == frame_pointer_rtx
4104 && GET_CODE (XEXP (XEXP (canon_mem, 0), 1)) == CONST_INT))
4107 /* Store a copy of mem, otherwise the address may be scrogged
4108 by find_auto_inc. This matters because insn_dead_p uses
4109 an rtx_equal_p check to determine if two addresses are
4110 the same. This works before find_auto_inc, but fails
4111 after find_auto_inc, causing discrepencies between the
4112 set of live registers calculated during the
4113 calculate_global_regs_live phase and what actually exists
4114 after flow completes, leading to aborts. */
4115 if (flags & PROP_AUTOINC)
4116 mem = shallow_copy_rtx (mem);
4118 pbi->mem_set_list = alloc_EXPR_LIST (0, mem, pbi->mem_set_list);
4119 if (++pbi->mem_set_list_len >= MAX_MEM_SET_LIST_LEN)
4128 /* Release a propagate_block_info struct. */
4131 free_propagate_block_info (pbi)
4132 struct propagate_block_info *pbi;
4134 free_EXPR_LIST_list (&pbi->mem_set_list);
4136 BITMAP_XFREE (pbi->new_set);
4138 #ifdef HAVE_conditional_execution
4139 splay_tree_delete (pbi->reg_cond_dead);
4140 BITMAP_XFREE (pbi->reg_cond_reg);
4143 if (pbi->reg_next_use)
4144 free (pbi->reg_next_use);
4149 /* Compute the registers live at the beginning of a basic block BB from
4150 those live at the end.
4152 When called, REG_LIVE contains those live at the end. On return, it
4153 contains those live at the beginning.
4155 LOCAL_SET, if non-null, will be set with all registers killed
4156 unconditionally by this basic block.
4157 Likewise, COND_LOCAL_SET, if non-null, will be set with all registers
4158 killed conditionally by this basic block. If there is any unconditional
4159 set of a register, then the corresponding bit will be set in LOCAL_SET
4160 and cleared in COND_LOCAL_SET.
4161 It is valid for LOCAL_SET and COND_LOCAL_SET to be the same set. In this
4162 case, the resulting set will be equal to the union of the two sets that
4163 would otherwise be computed. */
4166 propagate_block (bb, live, local_set, cond_local_set, flags)
4170 regset cond_local_set;
4173 struct propagate_block_info *pbi;
4176 pbi = init_propagate_block_info (bb, live, local_set, cond_local_set, flags);
4178 if (flags & PROP_REG_INFO)
4182 /* Process the regs live at the end of the block.
4183 Mark them as not local to any one basic block. */
4184 EXECUTE_IF_SET_IN_REG_SET (live, 0, i,
4185 { REG_BASIC_BLOCK (i) = REG_BLOCK_GLOBAL; });
4188 /* Scan the block an insn at a time from end to beginning. */
4190 for (insn = bb->end;; insn = prev)
4192 /* If this is a call to `setjmp' et al, warn if any
4193 non-volatile datum is live. */
4194 if ((flags & PROP_REG_INFO)
4195 && GET_CODE (insn) == NOTE
4196 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_SETJMP)
4197 IOR_REG_SET (regs_live_at_setjmp, pbi->reg_live);
4199 prev = propagate_one_insn (pbi, insn);
4201 if (insn == bb->head)
4205 free_propagate_block_info (pbi);
4208 /* Return 1 if X (the body of an insn, or part of it) is just dead stores
4209 (SET expressions whose destinations are registers dead after the insn).
4210 NEEDED is the regset that says which regs are alive after the insn.
4212 Unless CALL_OK is non-zero, an insn is needed if it contains a CALL.
4214 If X is the entire body of an insn, NOTES contains the reg notes
4215 pertaining to the insn. */
4218 insn_dead_p (pbi, x, call_ok, notes)
4219 struct propagate_block_info *pbi;
4222 rtx notes ATTRIBUTE_UNUSED;
4224 enum rtx_code code = GET_CODE (x);
4227 /* If flow is invoked after reload, we must take existing AUTO_INC
4228 expresions into account. */
4229 if (reload_completed)
4231 for (; notes; notes = XEXP (notes, 1))
4233 if (REG_NOTE_KIND (notes) == REG_INC)
4235 int regno = REGNO (XEXP (notes, 0));
4237 /* Don't delete insns to set global regs. */
4238 if ((regno < FIRST_PSEUDO_REGISTER && global_regs[regno])
4239 || REGNO_REG_SET_P (pbi->reg_live, regno))
4246 /* If setting something that's a reg or part of one,
4247 see if that register's altered value will be live. */
4251 rtx r = SET_DEST (x);
4254 if (GET_CODE (r) == CC0)
4255 return ! pbi->cc0_live;
4258 /* A SET that is a subroutine call cannot be dead. */
4259 if (GET_CODE (SET_SRC (x)) == CALL)
4265 /* Don't eliminate loads from volatile memory or volatile asms. */
4266 else if (volatile_refs_p (SET_SRC (x)))
4269 if (GET_CODE (r) == MEM)
4273 if (MEM_VOLATILE_P (r))
4276 /* Walk the set of memory locations we are currently tracking
4277 and see if one is an identical match to this memory location.
4278 If so, this memory write is dead (remember, we're walking
4279 backwards from the end of the block to the start). Since
4280 rtx_equal_p does not check the alias set or flags, we also
4281 must have the potential for them to conflict (anti_dependence). */
4282 for (temp = pbi->mem_set_list; temp != 0; temp = XEXP (temp, 1))
4283 if (anti_dependence (r, XEXP (temp, 0)))
4285 rtx mem = XEXP (temp, 0);
4287 if (rtx_equal_p (mem, r))
4290 /* Check if memory reference matches an auto increment. Only
4291 post increment/decrement or modify are valid. */
4292 if (GET_MODE (mem) == GET_MODE (r)
4293 && (GET_CODE (XEXP (mem, 0)) == POST_DEC
4294 || GET_CODE (XEXP (mem, 0)) == POST_INC
4295 || GET_CODE (XEXP (mem, 0)) == POST_MODIFY)
4296 && GET_MODE (XEXP (mem, 0)) == GET_MODE (r)
4297 && rtx_equal_p (XEXP (XEXP (mem, 0), 0), XEXP (r, 0)))
4304 while (GET_CODE (r) == SUBREG
4305 || GET_CODE (r) == STRICT_LOW_PART
4306 || GET_CODE (r) == ZERO_EXTRACT)
4309 if (GET_CODE (r) == REG)
4311 int regno = REGNO (r);
4314 if (REGNO_REG_SET_P (pbi->reg_live, regno))
4317 /* If this is a hard register, verify that subsequent
4318 words are not needed. */
4319 if (regno < FIRST_PSEUDO_REGISTER)
4321 int n = HARD_REGNO_NREGS (regno, GET_MODE (r));
4324 if (REGNO_REG_SET_P (pbi->reg_live, regno+n))
4328 /* Don't delete insns to set global regs. */
4329 if (regno < FIRST_PSEUDO_REGISTER && global_regs[regno])
4332 /* Make sure insns to set the stack pointer aren't deleted. */
4333 if (regno == STACK_POINTER_REGNUM)
4336 /* ??? These bits might be redundant with the force live bits
4337 in calculate_global_regs_live. We would delete from
4338 sequential sets; whether this actually affects real code
4339 for anything but the stack pointer I don't know. */
4340 /* Make sure insns to set the frame pointer aren't deleted. */
4341 if (regno == FRAME_POINTER_REGNUM
4342 && (! reload_completed || frame_pointer_needed))
4344 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
4345 if (regno == HARD_FRAME_POINTER_REGNUM
4346 && (! reload_completed || frame_pointer_needed))
4350 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
4351 /* Make sure insns to set arg pointer are never deleted
4352 (if the arg pointer isn't fixed, there will be a USE
4353 for it, so we can treat it normally). */
4354 if (regno == ARG_POINTER_REGNUM && fixed_regs[regno])
4358 /* Otherwise, the set is dead. */
4364 /* If performing several activities, insn is dead if each activity
4365 is individually dead. Also, CLOBBERs and USEs can be ignored; a
4366 CLOBBER or USE that's inside a PARALLEL doesn't make the insn
4368 else if (code == PARALLEL)
4370 int i = XVECLEN (x, 0);
4372 for (i--; i >= 0; i--)
4373 if (GET_CODE (XVECEXP (x, 0, i)) != CLOBBER
4374 && GET_CODE (XVECEXP (x, 0, i)) != USE
4375 && ! insn_dead_p (pbi, XVECEXP (x, 0, i), call_ok, NULL_RTX))
4381 /* A CLOBBER of a pseudo-register that is dead serves no purpose. That
4382 is not necessarily true for hard registers. */
4383 else if (code == CLOBBER && GET_CODE (XEXP (x, 0)) == REG
4384 && REGNO (XEXP (x, 0)) >= FIRST_PSEUDO_REGISTER
4385 && ! REGNO_REG_SET_P (pbi->reg_live, REGNO (XEXP (x, 0))))
4388 /* We do not check other CLOBBER or USE here. An insn consisting of just
4389 a CLOBBER or just a USE should not be deleted. */
4393 /* If INSN is the last insn in a libcall, and assuming INSN is dead,
4394 return 1 if the entire library call is dead.
4395 This is true if INSN copies a register (hard or pseudo)
4396 and if the hard return reg of the call insn is dead.
4397 (The caller should have tested the destination of the SET inside
4398 INSN already for death.)
4400 If this insn doesn't just copy a register, then we don't
4401 have an ordinary libcall. In that case, cse could not have
4402 managed to substitute the source for the dest later on,
4403 so we can assume the libcall is dead.
4405 PBI is the block info giving pseudoregs live before this insn.
4406 NOTE is the REG_RETVAL note of the insn. */
4409 libcall_dead_p (pbi, note, insn)
4410 struct propagate_block_info *pbi;
4414 rtx x = single_set (insn);
4418 register rtx r = SET_SRC (x);
4419 if (GET_CODE (r) == REG)
4421 rtx call = XEXP (note, 0);
4425 /* Find the call insn. */
4426 while (call != insn && GET_CODE (call) != CALL_INSN)
4427 call = NEXT_INSN (call);
4429 /* If there is none, do nothing special,
4430 since ordinary death handling can understand these insns. */
4434 /* See if the hard reg holding the value is dead.
4435 If this is a PARALLEL, find the call within it. */
4436 call_pat = PATTERN (call);
4437 if (GET_CODE (call_pat) == PARALLEL)
4439 for (i = XVECLEN (call_pat, 0) - 1; i >= 0; i--)
4440 if (GET_CODE (XVECEXP (call_pat, 0, i)) == SET
4441 && GET_CODE (SET_SRC (XVECEXP (call_pat, 0, i))) == CALL)
4444 /* This may be a library call that is returning a value
4445 via invisible pointer. Do nothing special, since
4446 ordinary death handling can understand these insns. */
4450 call_pat = XVECEXP (call_pat, 0, i);
4453 return insn_dead_p (pbi, call_pat, 1, REG_NOTES (call));
4459 /* Return 1 if register REGNO was used before it was set, i.e. if it is
4460 live at function entry. Don't count global register variables, variables
4461 in registers that can be used for function arg passing, or variables in
4462 fixed hard registers. */
4465 regno_uninitialized (regno)
4468 if (n_basic_blocks == 0
4469 || (regno < FIRST_PSEUDO_REGISTER
4470 && (global_regs[regno]
4471 || fixed_regs[regno]
4472 || FUNCTION_ARG_REGNO_P (regno))))
4475 return REGNO_REG_SET_P (BASIC_BLOCK (0)->global_live_at_start, regno);
4478 /* 1 if register REGNO was alive at a place where `setjmp' was called
4479 and was set more than once or is an argument.
4480 Such regs may be clobbered by `longjmp'. */
4483 regno_clobbered_at_setjmp (regno)
4486 if (n_basic_blocks == 0)
4489 return ((REG_N_SETS (regno) > 1
4490 || REGNO_REG_SET_P (BASIC_BLOCK (0)->global_live_at_start, regno))
4491 && REGNO_REG_SET_P (regs_live_at_setjmp, regno));
4494 /* INSN references memory, possibly using autoincrement addressing modes.
4495 Find any entries on the mem_set_list that need to be invalidated due
4496 to an address change. */
4499 invalidate_mems_from_autoinc (pbi, insn)
4500 struct propagate_block_info *pbi;
4503 rtx note = REG_NOTES (insn);
4504 for (note = REG_NOTES (insn); note; note = XEXP (note, 1))
4506 if (REG_NOTE_KIND (note) == REG_INC)
4508 rtx temp = pbi->mem_set_list;
4509 rtx prev = NULL_RTX;
4514 next = XEXP (temp, 1);
4515 if (reg_overlap_mentioned_p (XEXP (note, 0), XEXP (temp, 0)))
4517 /* Splice temp out of list. */
4519 XEXP (prev, 1) = next;
4521 pbi->mem_set_list = next;
4522 free_EXPR_LIST_node (temp);
4523 pbi->mem_set_list_len--;
4533 /* EXP is either a MEM or a REG. Remove any dependant entries
4534 from pbi->mem_set_list. */
4537 invalidate_mems_from_set (pbi, exp)
4538 struct propagate_block_info *pbi;
4541 rtx temp = pbi->mem_set_list;
4542 rtx prev = NULL_RTX;
4547 next = XEXP (temp, 1);
4548 if ((GET_CODE (exp) == MEM
4549 && output_dependence (XEXP (temp, 0), exp))
4550 || (GET_CODE (exp) == REG
4551 && reg_overlap_mentioned_p (exp, XEXP (temp, 0))))
4553 /* Splice this entry out of the list. */
4555 XEXP (prev, 1) = next;
4557 pbi->mem_set_list = next;
4558 free_EXPR_LIST_node (temp);
4559 pbi->mem_set_list_len--;
4567 /* Process the registers that are set within X. Their bits are set to
4568 1 in the regset DEAD, because they are dead prior to this insn.
4570 If INSN is nonzero, it is the insn being processed.
4572 FLAGS is the set of operations to perform. */
4575 mark_set_regs (pbi, x, insn)
4576 struct propagate_block_info *pbi;
4579 rtx cond = NULL_RTX;
4584 for (link = REG_NOTES (insn); link; link = XEXP (link, 1))
4586 if (REG_NOTE_KIND (link) == REG_INC)
4587 mark_set_1 (pbi, SET, XEXP (link, 0),
4588 (GET_CODE (x) == COND_EXEC
4589 ? COND_EXEC_TEST (x) : NULL_RTX),
4593 switch (code = GET_CODE (x))
4597 mark_set_1 (pbi, code, SET_DEST (x), cond, insn, pbi->flags);
4601 cond = COND_EXEC_TEST (x);
4602 x = COND_EXEC_CODE (x);
4608 for (i = XVECLEN (x, 0) - 1; i >= 0; i--)
4610 rtx sub = XVECEXP (x, 0, i);
4611 switch (code = GET_CODE (sub))
4614 if (cond != NULL_RTX)
4617 cond = COND_EXEC_TEST (sub);
4618 sub = COND_EXEC_CODE (sub);
4619 if (GET_CODE (sub) != SET && GET_CODE (sub) != CLOBBER)
4625 mark_set_1 (pbi, code, SET_DEST (sub), cond, insn, pbi->flags);
4640 /* Process a single set, which appears in INSN. REG (which may not
4641 actually be a REG, it may also be a SUBREG, PARALLEL, etc.) is
4642 being set using the CODE (which may be SET, CLOBBER, or COND_EXEC).
4643 If the set is conditional (because it appear in a COND_EXEC), COND
4644 will be the condition. */
4647 mark_set_1 (pbi, code, reg, cond, insn, flags)
4648 struct propagate_block_info *pbi;
4650 rtx reg, cond, insn;
4653 int regno_first = -1, regno_last = -1;
4654 unsigned long not_dead = 0;
4657 /* Modifying just one hardware register of a multi-reg value or just a
4658 byte field of a register does not mean the value from before this insn
4659 is now dead. Of course, if it was dead after it's unused now. */
4661 switch (GET_CODE (reg))
4664 /* Some targets place small structures in registers for return values of
4665 functions. We have to detect this case specially here to get correct
4666 flow information. */
4667 for (i = XVECLEN (reg, 0) - 1; i >= 0; i--)
4668 if (XEXP (XVECEXP (reg, 0, i), 0) != 0)
4669 mark_set_1 (pbi, code, XEXP (XVECEXP (reg, 0, i), 0), cond, insn,
4675 case STRICT_LOW_PART:
4676 /* ??? Assumes STRICT_LOW_PART not used on multi-word registers. */
4678 reg = XEXP (reg, 0);
4679 while (GET_CODE (reg) == SUBREG
4680 || GET_CODE (reg) == ZERO_EXTRACT
4681 || GET_CODE (reg) == SIGN_EXTRACT
4682 || GET_CODE (reg) == STRICT_LOW_PART);
4683 if (GET_CODE (reg) == MEM)
4685 not_dead = (unsigned long) REGNO_REG_SET_P (pbi->reg_live, REGNO (reg));
4689 regno_last = regno_first = REGNO (reg);
4690 if (regno_first < FIRST_PSEUDO_REGISTER)
4691 regno_last += HARD_REGNO_NREGS (regno_first, GET_MODE (reg)) - 1;
4695 if (GET_CODE (SUBREG_REG (reg)) == REG)
4697 enum machine_mode outer_mode = GET_MODE (reg);
4698 enum machine_mode inner_mode = GET_MODE (SUBREG_REG (reg));
4700 /* Identify the range of registers affected. This is moderately
4701 tricky for hard registers. See alter_subreg. */
4703 regno_last = regno_first = REGNO (SUBREG_REG (reg));
4704 if (regno_first < FIRST_PSEUDO_REGISTER)
4706 regno_first += subreg_regno_offset (regno_first, inner_mode,
4709 regno_last = (regno_first
4710 + HARD_REGNO_NREGS (regno_first, outer_mode) - 1);
4712 /* Since we've just adjusted the register number ranges, make
4713 sure REG matches. Otherwise some_was_live will be clear
4714 when it shouldn't have been, and we'll create incorrect
4715 REG_UNUSED notes. */
4716 reg = gen_rtx_REG (outer_mode, regno_first);
4720 /* If the number of words in the subreg is less than the number
4721 of words in the full register, we have a well-defined partial
4722 set. Otherwise the high bits are undefined.
4724 This is only really applicable to pseudos, since we just took
4725 care of multi-word hard registers. */
4726 if (((GET_MODE_SIZE (outer_mode)
4727 + UNITS_PER_WORD - 1) / UNITS_PER_WORD)
4728 < ((GET_MODE_SIZE (inner_mode)
4729 + UNITS_PER_WORD - 1) / UNITS_PER_WORD))
4730 not_dead = (unsigned long) REGNO_REG_SET_P (pbi->reg_live,
4733 reg = SUBREG_REG (reg);
4737 reg = SUBREG_REG (reg);
4744 /* If this set is a MEM, then it kills any aliased writes.
4745 If this set is a REG, then it kills any MEMs which use the reg. */
4746 if (optimize && (flags & PROP_SCAN_DEAD_CODE))
4748 if (GET_CODE (reg) == MEM || GET_CODE (reg) == REG)
4749 invalidate_mems_from_set (pbi, reg);
4751 /* If the memory reference had embedded side effects (autoincrement
4752 address modes. Then we may need to kill some entries on the
4754 if (insn && GET_CODE (reg) == MEM)
4755 invalidate_mems_from_autoinc (pbi, insn);
4757 if (pbi->mem_set_list_len < MAX_MEM_SET_LIST_LEN
4758 && GET_CODE (reg) == MEM && ! side_effects_p (reg)
4759 /* ??? With more effort we could track conditional memory life. */
4761 /* We do not know the size of a BLKmode store, so we do not track
4762 them for redundant store elimination. */
4763 && GET_MODE (reg) != BLKmode
4764 /* There are no REG_INC notes for SP, so we can't assume we'll see
4765 everything that invalidates it. To be safe, don't eliminate any
4766 stores though SP; none of them should be redundant anyway. */
4767 && ! reg_mentioned_p (stack_pointer_rtx, reg))
4770 /* Store a copy of mem, otherwise the address may be
4771 scrogged by find_auto_inc. */
4772 if (flags & PROP_AUTOINC)
4773 reg = shallow_copy_rtx (reg);
4775 pbi->mem_set_list = alloc_EXPR_LIST (0, reg, pbi->mem_set_list);
4776 pbi->mem_set_list_len++;
4780 if (GET_CODE (reg) == REG
4781 && ! (regno_first == FRAME_POINTER_REGNUM
4782 && (! reload_completed || frame_pointer_needed))
4783 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
4784 && ! (regno_first == HARD_FRAME_POINTER_REGNUM
4785 && (! reload_completed || frame_pointer_needed))
4787 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
4788 && ! (regno_first == ARG_POINTER_REGNUM && fixed_regs[regno_first])
4792 int some_was_live = 0, some_was_dead = 0;
4794 for (i = regno_first; i <= regno_last; ++i)
4796 int needed_regno = REGNO_REG_SET_P (pbi->reg_live, i);
4799 /* Order of the set operation matters here since both
4800 sets may be the same. */
4801 CLEAR_REGNO_REG_SET (pbi->cond_local_set, i);
4802 if (cond != NULL_RTX
4803 && ! REGNO_REG_SET_P (pbi->local_set, i))
4804 SET_REGNO_REG_SET (pbi->cond_local_set, i);
4806 SET_REGNO_REG_SET (pbi->local_set, i);
4808 if (code != CLOBBER)
4809 SET_REGNO_REG_SET (pbi->new_set, i);
4811 some_was_live |= needed_regno;
4812 some_was_dead |= ! needed_regno;
4815 #ifdef HAVE_conditional_execution
4816 /* Consider conditional death in deciding that the register needs
4818 if (some_was_live && ! not_dead
4819 /* The stack pointer is never dead. Well, not strictly true,
4820 but it's very difficult to tell from here. Hopefully
4821 combine_stack_adjustments will fix up the most egregious
4823 && regno_first != STACK_POINTER_REGNUM)
4825 for (i = regno_first; i <= regno_last; ++i)
4826 if (! mark_regno_cond_dead (pbi, i, cond))
4827 not_dead |= ((unsigned long) 1) << (i - regno_first);
4831 /* Additional data to record if this is the final pass. */
4832 if (flags & (PROP_LOG_LINKS | PROP_REG_INFO
4833 | PROP_DEATH_NOTES | PROP_AUTOINC))
4836 register int blocknum = pbi->bb->index;
4839 if (flags & (PROP_LOG_LINKS | PROP_AUTOINC))
4841 y = pbi->reg_next_use[regno_first];
4843 /* The next use is no longer next, since a store intervenes. */
4844 for (i = regno_first; i <= regno_last; ++i)
4845 pbi->reg_next_use[i] = 0;
4848 if (flags & PROP_REG_INFO)
4850 for (i = regno_first; i <= regno_last; ++i)
4852 /* Count (weighted) references, stores, etc. This counts a
4853 register twice if it is modified, but that is correct. */
4854 REG_N_SETS (i) += 1;
4855 REG_N_REFS (i) += (optimize_size ? 1
4856 : pbi->bb->loop_depth + 1);
4858 /* The insns where a reg is live are normally counted
4859 elsewhere, but we want the count to include the insn
4860 where the reg is set, and the normal counting mechanism
4861 would not count it. */
4862 REG_LIVE_LENGTH (i) += 1;
4865 /* If this is a hard reg, record this function uses the reg. */
4866 if (regno_first < FIRST_PSEUDO_REGISTER)
4868 for (i = regno_first; i <= regno_last; i++)
4869 regs_ever_live[i] = 1;
4873 /* Keep track of which basic blocks each reg appears in. */
4874 if (REG_BASIC_BLOCK (regno_first) == REG_BLOCK_UNKNOWN)
4875 REG_BASIC_BLOCK (regno_first) = blocknum;
4876 else if (REG_BASIC_BLOCK (regno_first) != blocknum)
4877 REG_BASIC_BLOCK (regno_first) = REG_BLOCK_GLOBAL;
4881 if (! some_was_dead)
4883 if (flags & PROP_LOG_LINKS)
4885 /* Make a logical link from the next following insn
4886 that uses this register, back to this insn.
4887 The following insns have already been processed.
4889 We don't build a LOG_LINK for hard registers containing
4890 in ASM_OPERANDs. If these registers get replaced,
4891 we might wind up changing the semantics of the insn,
4892 even if reload can make what appear to be valid
4893 assignments later. */
4894 if (y && (BLOCK_NUM (y) == blocknum)
4895 && (regno_first >= FIRST_PSEUDO_REGISTER
4896 || asm_noperands (PATTERN (y)) < 0))
4897 LOG_LINKS (y) = alloc_INSN_LIST (insn, LOG_LINKS (y));
4902 else if (! some_was_live)
4904 if (flags & PROP_REG_INFO)
4905 REG_N_DEATHS (regno_first) += 1;
4907 if (flags & PROP_DEATH_NOTES)
4909 /* Note that dead stores have already been deleted
4910 when possible. If we get here, we have found a
4911 dead store that cannot be eliminated (because the
4912 same insn does something useful). Indicate this
4913 by marking the reg being set as dying here. */
4915 = alloc_EXPR_LIST (REG_UNUSED, reg, REG_NOTES (insn));
4920 if (flags & PROP_DEATH_NOTES)
4922 /* This is a case where we have a multi-word hard register
4923 and some, but not all, of the words of the register are
4924 needed in subsequent insns. Write REG_UNUSED notes
4925 for those parts that were not needed. This case should
4928 for (i = regno_first; i <= regno_last; ++i)
4929 if (! REGNO_REG_SET_P (pbi->reg_live, i))
4931 = alloc_EXPR_LIST (REG_UNUSED,
4932 gen_rtx_REG (reg_raw_mode[i], i),
4938 /* Mark the register as being dead. */
4940 /* The stack pointer is never dead. Well, not strictly true,
4941 but it's very difficult to tell from here. Hopefully
4942 combine_stack_adjustments will fix up the most egregious
4944 && regno_first != STACK_POINTER_REGNUM)
4946 for (i = regno_first; i <= regno_last; ++i)
4947 if (!(not_dead & (((unsigned long) 1) << (i - regno_first))))
4948 CLEAR_REGNO_REG_SET (pbi->reg_live, i);
4951 else if (GET_CODE (reg) == REG)
4953 if (flags & (PROP_LOG_LINKS | PROP_AUTOINC))
4954 pbi->reg_next_use[regno_first] = 0;
4957 /* If this is the last pass and this is a SCRATCH, show it will be dying
4958 here and count it. */
4959 else if (GET_CODE (reg) == SCRATCH)
4961 if (flags & PROP_DEATH_NOTES)
4963 = alloc_EXPR_LIST (REG_UNUSED, reg, REG_NOTES (insn));
4967 #ifdef HAVE_conditional_execution
4968 /* Mark REGNO conditionally dead.
4969 Return true if the register is now unconditionally dead. */
4972 mark_regno_cond_dead (pbi, regno, cond)
4973 struct propagate_block_info *pbi;
4977 /* If this is a store to a predicate register, the value of the
4978 predicate is changing, we don't know that the predicate as seen
4979 before is the same as that seen after. Flush all dependent
4980 conditions from reg_cond_dead. This will make all such
4981 conditionally live registers unconditionally live. */
4982 if (REGNO_REG_SET_P (pbi->reg_cond_reg, regno))
4983 flush_reg_cond_reg (pbi, regno);
4985 /* If this is an unconditional store, remove any conditional
4986 life that may have existed. */
4987 if (cond == NULL_RTX)
4988 splay_tree_remove (pbi->reg_cond_dead, regno);
4991 splay_tree_node node;
4992 struct reg_cond_life_info *rcli;
4995 /* Otherwise this is a conditional set. Record that fact.
4996 It may have been conditionally used, or there may be a
4997 subsequent set with a complimentary condition. */
4999 node = splay_tree_lookup (pbi->reg_cond_dead, regno);
5002 /* The register was unconditionally live previously.
5003 Record the current condition as the condition under
5004 which it is dead. */
5005 rcli = (struct reg_cond_life_info *) xmalloc (sizeof (*rcli));
5006 rcli->condition = cond;
5007 rcli->stores = cond;
5008 rcli->orig_condition = const0_rtx;
5009 splay_tree_insert (pbi->reg_cond_dead, regno,
5010 (splay_tree_value) rcli);
5012 SET_REGNO_REG_SET (pbi->reg_cond_reg, REGNO (XEXP (cond, 0)));
5014 /* Not unconditionaly dead. */
5019 /* The register was conditionally live previously.
5020 Add the new condition to the old. */
5021 rcli = (struct reg_cond_life_info *) node->value;
5022 ncond = rcli->condition;
5023 ncond = ior_reg_cond (ncond, cond, 1);
5024 if (rcli->stores == const0_rtx)
5025 rcli->stores = cond;
5026 else if (rcli->stores != const1_rtx)
5027 rcli->stores = ior_reg_cond (rcli->stores, cond, 1);
5029 /* If the register is now unconditionally dead, remove the entry
5030 in the splay_tree. A register is unconditionally dead if the
5031 dead condition ncond is true. A register is also unconditionally
5032 dead if the sum of all conditional stores is an unconditional
5033 store (stores is true), and the dead condition is identically the
5034 same as the original dead condition initialized at the end of
5035 the block. This is a pointer compare, not an rtx_equal_p
5037 if (ncond == const1_rtx
5038 || (ncond == rcli->orig_condition && rcli->stores == const1_rtx))
5039 splay_tree_remove (pbi->reg_cond_dead, regno);
5042 rcli->condition = ncond;
5044 SET_REGNO_REG_SET (pbi->reg_cond_reg, REGNO (XEXP (cond, 0)));
5046 /* Not unconditionaly dead. */
5055 /* Called from splay_tree_delete for pbi->reg_cond_life. */
5058 free_reg_cond_life_info (value)
5059 splay_tree_value value;
5061 struct reg_cond_life_info *rcli = (struct reg_cond_life_info *) value;
5065 /* Helper function for flush_reg_cond_reg. */
5068 flush_reg_cond_reg_1 (node, data)
5069 splay_tree_node node;
5072 struct reg_cond_life_info *rcli;
5073 int *xdata = (int *) data;
5074 unsigned int regno = xdata[0];
5076 /* Don't need to search if last flushed value was farther on in
5077 the in-order traversal. */
5078 if (xdata[1] >= (int) node->key)
5081 /* Splice out portions of the expression that refer to regno. */
5082 rcli = (struct reg_cond_life_info *) node->value;
5083 rcli->condition = elim_reg_cond (rcli->condition, regno);
5084 if (rcli->stores != const0_rtx && rcli->stores != const1_rtx)
5085 rcli->stores = elim_reg_cond (rcli->stores, regno);
5087 /* If the entire condition is now false, signal the node to be removed. */
5088 if (rcli->condition == const0_rtx)
5090 xdata[1] = node->key;
5093 else if (rcli->condition == const1_rtx)
5099 /* Flush all (sub) expressions referring to REGNO from REG_COND_LIVE. */
5102 flush_reg_cond_reg (pbi, regno)
5103 struct propagate_block_info *pbi;
5110 while (splay_tree_foreach (pbi->reg_cond_dead,
5111 flush_reg_cond_reg_1, pair) == -1)
5112 splay_tree_remove (pbi->reg_cond_dead, pair[1]);
5114 CLEAR_REGNO_REG_SET (pbi->reg_cond_reg, regno);
5117 /* Logical arithmetic on predicate conditions. IOR, NOT and AND.
5118 For ior/and, the ADD flag determines whether we want to add the new
5119 condition X to the old one unconditionally. If it is zero, we will
5120 only return a new expression if X allows us to simplify part of
5121 OLD, otherwise we return OLD unchanged to the caller.
5122 If ADD is nonzero, we will return a new condition in all cases. The
5123 toplevel caller of one of these functions should always pass 1 for
5127 ior_reg_cond (old, x, add)
5133 if (GET_RTX_CLASS (GET_CODE (old)) == '<')
5135 if (GET_RTX_CLASS (GET_CODE (x)) == '<'
5136 && REVERSE_CONDEXEC_PREDICATES_P (GET_CODE (x), GET_CODE (old))
5137 && REGNO (XEXP (x, 0)) == REGNO (XEXP (old, 0)))
5139 if (GET_CODE (x) == GET_CODE (old)
5140 && REGNO (XEXP (x, 0)) == REGNO (XEXP (old, 0)))
5144 return gen_rtx_IOR (0, old, x);
5147 switch (GET_CODE (old))
5150 op0 = ior_reg_cond (XEXP (old, 0), x, 0);
5151 op1 = ior_reg_cond (XEXP (old, 1), x, 0);
5152 if (op0 != XEXP (old, 0) || op1 != XEXP (old, 1))
5154 if (op0 == const0_rtx)
5156 if (op1 == const0_rtx)
5158 if (op0 == const1_rtx || op1 == const1_rtx)
5160 if (op0 == XEXP (old, 0))
5161 op0 = gen_rtx_IOR (0, op0, x);
5163 op1 = gen_rtx_IOR (0, op1, x);
5164 return gen_rtx_IOR (0, op0, op1);
5168 return gen_rtx_IOR (0, old, x);
5171 op0 = ior_reg_cond (XEXP (old, 0), x, 0);
5172 op1 = ior_reg_cond (XEXP (old, 1), x, 0);
5173 if (op0 != XEXP (old, 0) || op1 != XEXP (old, 1))
5175 if (op0 == const1_rtx)
5177 if (op1 == const1_rtx)
5179 if (op0 == const0_rtx || op1 == const0_rtx)
5181 if (op0 == XEXP (old, 0))
5182 op0 = gen_rtx_IOR (0, op0, x);
5184 op1 = gen_rtx_IOR (0, op1, x);
5185 return gen_rtx_AND (0, op0, op1);
5189 return gen_rtx_IOR (0, old, x);
5192 op0 = and_reg_cond (XEXP (old, 0), not_reg_cond (x), 0);
5193 if (op0 != XEXP (old, 0))
5194 return not_reg_cond (op0);
5197 return gen_rtx_IOR (0, old, x);
5208 enum rtx_code x_code;
5210 if (x == const0_rtx)
5212 else if (x == const1_rtx)
5214 x_code = GET_CODE (x);
5217 if (GET_RTX_CLASS (x_code) == '<'
5218 && GET_CODE (XEXP (x, 0)) == REG)
5220 if (XEXP (x, 1) != const0_rtx)
5223 return gen_rtx_fmt_ee (reverse_condition (x_code),
5224 VOIDmode, XEXP (x, 0), const0_rtx);
5226 return gen_rtx_NOT (0, x);
5230 and_reg_cond (old, x, add)
5236 if (GET_RTX_CLASS (GET_CODE (old)) == '<')
5238 if (GET_RTX_CLASS (GET_CODE (x)) == '<'
5239 && GET_CODE (x) == reverse_condition (GET_CODE (old))
5240 && REGNO (XEXP (x, 0)) == REGNO (XEXP (old, 0)))
5242 if (GET_CODE (x) == GET_CODE (old)
5243 && REGNO (XEXP (x, 0)) == REGNO (XEXP (old, 0)))
5247 return gen_rtx_AND (0, old, x);
5250 switch (GET_CODE (old))
5253 op0 = and_reg_cond (XEXP (old, 0), x, 0);
5254 op1 = and_reg_cond (XEXP (old, 1), x, 0);
5255 if (op0 != XEXP (old, 0) || op1 != XEXP (old, 1))
5257 if (op0 == const0_rtx)
5259 if (op1 == const0_rtx)
5261 if (op0 == const1_rtx || op1 == const1_rtx)
5263 if (op0 == XEXP (old, 0))
5264 op0 = gen_rtx_AND (0, op0, x);
5266 op1 = gen_rtx_AND (0, op1, x);
5267 return gen_rtx_IOR (0, op0, op1);
5271 return gen_rtx_AND (0, old, x);
5274 op0 = and_reg_cond (XEXP (old, 0), x, 0);
5275 op1 = and_reg_cond (XEXP (old, 1), x, 0);
5276 if (op0 != XEXP (old, 0) || op1 != XEXP (old, 1))
5278 if (op0 == const1_rtx)
5280 if (op1 == const1_rtx)
5282 if (op0 == const0_rtx || op1 == const0_rtx)
5284 if (op0 == XEXP (old, 0))
5285 op0 = gen_rtx_AND (0, op0, x);
5287 op1 = gen_rtx_AND (0, op1, x);
5288 return gen_rtx_AND (0, op0, op1);
5293 /* If X is identical to one of the existing terms of the AND,
5294 then just return what we already have. */
5295 /* ??? There really should be some sort of recursive check here in
5296 case there are nested ANDs. */
5297 if ((GET_CODE (XEXP (old, 0)) == GET_CODE (x)
5298 && REGNO (XEXP (XEXP (old, 0), 0)) == REGNO (XEXP (x, 0)))
5299 || (GET_CODE (XEXP (old, 1)) == GET_CODE (x)
5300 && REGNO (XEXP (XEXP (old, 1), 0)) == REGNO (XEXP (x, 0))))
5303 return gen_rtx_AND (0, old, x);
5306 op0 = ior_reg_cond (XEXP (old, 0), not_reg_cond (x), 0);
5307 if (op0 != XEXP (old, 0))
5308 return not_reg_cond (op0);
5311 return gen_rtx_AND (0, old, x);
5318 /* Given a condition X, remove references to reg REGNO and return the
5319 new condition. The removal will be done so that all conditions
5320 involving REGNO are considered to evaluate to false. This function
5321 is used when the value of REGNO changes. */
5324 elim_reg_cond (x, regno)
5330 if (GET_RTX_CLASS (GET_CODE (x)) == '<')
5332 if (REGNO (XEXP (x, 0)) == regno)
5337 switch (GET_CODE (x))
5340 op0 = elim_reg_cond (XEXP (x, 0), regno);
5341 op1 = elim_reg_cond (XEXP (x, 1), regno);
5342 if (op0 == const0_rtx || op1 == const0_rtx)
5344 if (op0 == const1_rtx)
5346 if (op1 == const1_rtx)
5348 if (op0 == XEXP (x, 0) && op1 == XEXP (x, 1))
5350 return gen_rtx_AND (0, op0, op1);
5353 op0 = elim_reg_cond (XEXP (x, 0), regno);
5354 op1 = elim_reg_cond (XEXP (x, 1), regno);
5355 if (op0 == const1_rtx || op1 == const1_rtx)
5357 if (op0 == const0_rtx)
5359 if (op1 == const0_rtx)
5361 if (op0 == XEXP (x, 0) && op1 == XEXP (x, 1))
5363 return gen_rtx_IOR (0, op0, op1);
5366 op0 = elim_reg_cond (XEXP (x, 0), regno);
5367 if (op0 == const0_rtx)
5369 if (op0 == const1_rtx)
5371 if (op0 != XEXP (x, 0))
5372 return not_reg_cond (op0);
5379 #endif /* HAVE_conditional_execution */
5383 /* Try to substitute the auto-inc expression INC as the address inside
5384 MEM which occurs in INSN. Currently, the address of MEM is an expression
5385 involving INCR_REG, and INCR is the next use of INCR_REG; it is an insn
5386 that has a single set whose source is a PLUS of INCR_REG and something
5390 attempt_auto_inc (pbi, inc, insn, mem, incr, incr_reg)
5391 struct propagate_block_info *pbi;
5392 rtx inc, insn, mem, incr, incr_reg;
5394 int regno = REGNO (incr_reg);
5395 rtx set = single_set (incr);
5396 rtx q = SET_DEST (set);
5397 rtx y = SET_SRC (set);
5398 int opnum = XEXP (y, 0) == incr_reg ? 0 : 1;
5400 /* Make sure this reg appears only once in this insn. */
5401 if (count_occurrences (PATTERN (insn), incr_reg, 1) != 1)
5404 if (dead_or_set_p (incr, incr_reg)
5405 /* Mustn't autoinc an eliminable register. */
5406 && (regno >= FIRST_PSEUDO_REGISTER
5407 || ! TEST_HARD_REG_BIT (elim_reg_set, regno)))
5409 /* This is the simple case. Try to make the auto-inc. If
5410 we can't, we are done. Otherwise, we will do any
5411 needed updates below. */
5412 if (! validate_change (insn, &XEXP (mem, 0), inc, 0))
5415 else if (GET_CODE (q) == REG
5416 /* PREV_INSN used here to check the semi-open interval
5418 && ! reg_used_between_p (q, PREV_INSN (insn), incr)
5419 /* We must also check for sets of q as q may be
5420 a call clobbered hard register and there may
5421 be a call between PREV_INSN (insn) and incr. */
5422 && ! reg_set_between_p (q, PREV_INSN (insn), incr))
5424 /* We have *p followed sometime later by q = p+size.
5425 Both p and q must be live afterward,
5426 and q is not used between INSN and its assignment.
5427 Change it to q = p, ...*q..., q = q+size.
5428 Then fall into the usual case. */
5432 emit_move_insn (q, incr_reg);
5433 insns = get_insns ();
5436 if (basic_block_for_insn)
5437 for (temp = insns; temp; temp = NEXT_INSN (temp))
5438 set_block_for_insn (temp, pbi->bb);
5440 /* If we can't make the auto-inc, or can't make the
5441 replacement into Y, exit. There's no point in making
5442 the change below if we can't do the auto-inc and doing
5443 so is not correct in the pre-inc case. */
5446 validate_change (insn, &XEXP (mem, 0), inc, 1);
5447 validate_change (incr, &XEXP (y, opnum), q, 1);
5448 if (! apply_change_group ())
5451 /* We now know we'll be doing this change, so emit the
5452 new insn(s) and do the updates. */
5453 emit_insns_before (insns, insn);
5455 if (pbi->bb->head == insn)
5456 pbi->bb->head = insns;
5458 /* INCR will become a NOTE and INSN won't contain a
5459 use of INCR_REG. If a use of INCR_REG was just placed in
5460 the insn before INSN, make that the next use.
5461 Otherwise, invalidate it. */
5462 if (GET_CODE (PREV_INSN (insn)) == INSN
5463 && GET_CODE (PATTERN (PREV_INSN (insn))) == SET
5464 && SET_SRC (PATTERN (PREV_INSN (insn))) == incr_reg)
5465 pbi->reg_next_use[regno] = PREV_INSN (insn);
5467 pbi->reg_next_use[regno] = 0;
5472 /* REGNO is now used in INCR which is below INSN, but
5473 it previously wasn't live here. If we don't mark
5474 it as live, we'll put a REG_DEAD note for it
5475 on this insn, which is incorrect. */
5476 SET_REGNO_REG_SET (pbi->reg_live, regno);
5478 /* If there are any calls between INSN and INCR, show
5479 that REGNO now crosses them. */
5480 for (temp = insn; temp != incr; temp = NEXT_INSN (temp))
5481 if (GET_CODE (temp) == CALL_INSN)
5482 REG_N_CALLS_CROSSED (regno)++;
5487 /* If we haven't returned, it means we were able to make the
5488 auto-inc, so update the status. First, record that this insn
5489 has an implicit side effect. */
5491 REG_NOTES (insn) = alloc_EXPR_LIST (REG_INC, incr_reg, REG_NOTES (insn));
5493 /* Modify the old increment-insn to simply copy
5494 the already-incremented value of our register. */
5495 if (! validate_change (incr, &SET_SRC (set), incr_reg, 0))
5498 /* If that makes it a no-op (copying the register into itself) delete
5499 it so it won't appear to be a "use" and a "set" of this
5501 if (REGNO (SET_DEST (set)) == REGNO (incr_reg))
5503 /* If the original source was dead, it's dead now. */
5506 while ((note = find_reg_note (incr, REG_DEAD, NULL_RTX)) != NULL_RTX)
5508 remove_note (incr, note);
5509 if (XEXP (note, 0) != incr_reg)
5510 CLEAR_REGNO_REG_SET (pbi->reg_live, REGNO (XEXP (note, 0)));
5513 PUT_CODE (incr, NOTE);
5514 NOTE_LINE_NUMBER (incr) = NOTE_INSN_DELETED;
5515 NOTE_SOURCE_FILE (incr) = 0;
5518 if (regno >= FIRST_PSEUDO_REGISTER)
5520 /* Count an extra reference to the reg. When a reg is
5521 incremented, spilling it is worse, so we want to make
5522 that less likely. */
5523 REG_N_REFS (regno) += (optimize_size ? 1 : pbi->bb->loop_depth + 1);
5525 /* Count the increment as a setting of the register,
5526 even though it isn't a SET in rtl. */
5527 REG_N_SETS (regno)++;
5531 /* X is a MEM found in INSN. See if we can convert it into an auto-increment
5535 find_auto_inc (pbi, x, insn)
5536 struct propagate_block_info *pbi;
5540 rtx addr = XEXP (x, 0);
5541 HOST_WIDE_INT offset = 0;
5542 rtx set, y, incr, inc_val;
5544 int size = GET_MODE_SIZE (GET_MODE (x));
5546 if (GET_CODE (insn) == JUMP_INSN)
5549 /* Here we detect use of an index register which might be good for
5550 postincrement, postdecrement, preincrement, or predecrement. */
5552 if (GET_CODE (addr) == PLUS && GET_CODE (XEXP (addr, 1)) == CONST_INT)
5553 offset = INTVAL (XEXP (addr, 1)), addr = XEXP (addr, 0);
5555 if (GET_CODE (addr) != REG)
5558 regno = REGNO (addr);
5560 /* Is the next use an increment that might make auto-increment? */
5561 incr = pbi->reg_next_use[regno];
5562 if (incr == 0 || BLOCK_NUM (incr) != BLOCK_NUM (insn))
5564 set = single_set (incr);
5565 if (set == 0 || GET_CODE (set) != SET)
5569 if (GET_CODE (y) != PLUS)
5572 if (REG_P (XEXP (y, 0)) && REGNO (XEXP (y, 0)) == REGNO (addr))
5573 inc_val = XEXP (y, 1);
5574 else if (REG_P (XEXP (y, 1)) && REGNO (XEXP (y, 1)) == REGNO (addr))
5575 inc_val = XEXP (y, 0);
5579 if (GET_CODE (inc_val) == CONST_INT)
5581 if (HAVE_POST_INCREMENT
5582 && (INTVAL (inc_val) == size && offset == 0))
5583 attempt_auto_inc (pbi, gen_rtx_POST_INC (Pmode, addr), insn, x,
5585 else if (HAVE_POST_DECREMENT
5586 && (INTVAL (inc_val) == -size && offset == 0))
5587 attempt_auto_inc (pbi, gen_rtx_POST_DEC (Pmode, addr), insn, x,
5589 else if (HAVE_PRE_INCREMENT
5590 && (INTVAL (inc_val) == size && offset == size))
5591 attempt_auto_inc (pbi, gen_rtx_PRE_INC (Pmode, addr), insn, x,
5593 else if (HAVE_PRE_DECREMENT
5594 && (INTVAL (inc_val) == -size && offset == -size))
5595 attempt_auto_inc (pbi, gen_rtx_PRE_DEC (Pmode, addr), insn, x,
5597 else if (HAVE_POST_MODIFY_DISP && offset == 0)
5598 attempt_auto_inc (pbi, gen_rtx_POST_MODIFY (Pmode, addr,
5599 gen_rtx_PLUS (Pmode,
5602 insn, x, incr, addr);
5604 else if (GET_CODE (inc_val) == REG
5605 && ! reg_set_between_p (inc_val, PREV_INSN (insn),
5609 if (HAVE_POST_MODIFY_REG && offset == 0)
5610 attempt_auto_inc (pbi, gen_rtx_POST_MODIFY (Pmode, addr,
5611 gen_rtx_PLUS (Pmode,
5614 insn, x, incr, addr);
5618 #endif /* AUTO_INC_DEC */
5621 mark_used_reg (pbi, reg, cond, insn)
5622 struct propagate_block_info *pbi;
5624 rtx cond ATTRIBUTE_UNUSED;
5627 unsigned int regno_first, regno_last, i;
5628 int some_was_live, some_was_dead, some_not_set;
5630 regno_last = regno_first = REGNO (reg);
5631 if (regno_first < FIRST_PSEUDO_REGISTER)
5632 regno_last += HARD_REGNO_NREGS (regno_first, GET_MODE (reg)) - 1;
5634 /* Find out if any of this register is live after this instruction. */
5635 some_was_live = some_was_dead = 0;
5636 for (i = regno_first; i <= regno_last; ++i)
5638 int needed_regno = REGNO_REG_SET_P (pbi->reg_live, i);
5639 some_was_live |= needed_regno;
5640 some_was_dead |= ! needed_regno;
5643 /* Find out if any of the register was set this insn. */
5645 for (i = regno_first; i <= regno_last; ++i)
5646 some_not_set |= ! REGNO_REG_SET_P (pbi->new_set, i);
5648 if (pbi->flags & (PROP_LOG_LINKS | PROP_AUTOINC))
5650 /* Record where each reg is used, so when the reg is set we know
5651 the next insn that uses it. */
5652 pbi->reg_next_use[regno_first] = insn;
5655 if (pbi->flags & PROP_REG_INFO)
5657 if (regno_first < FIRST_PSEUDO_REGISTER)
5659 /* If this is a register we are going to try to eliminate,
5660 don't mark it live here. If we are successful in
5661 eliminating it, it need not be live unless it is used for
5662 pseudos, in which case it will have been set live when it
5663 was allocated to the pseudos. If the register will not
5664 be eliminated, reload will set it live at that point.
5666 Otherwise, record that this function uses this register. */
5667 /* ??? The PPC backend tries to "eliminate" on the pic
5668 register to itself. This should be fixed. In the mean
5669 time, hack around it. */
5671 if (! (TEST_HARD_REG_BIT (elim_reg_set, regno_first)
5672 && (regno_first == FRAME_POINTER_REGNUM
5673 || regno_first == ARG_POINTER_REGNUM)))
5674 for (i = regno_first; i <= regno_last; ++i)
5675 regs_ever_live[i] = 1;
5679 /* Keep track of which basic block each reg appears in. */
5681 register int blocknum = pbi->bb->index;
5682 if (REG_BASIC_BLOCK (regno_first) == REG_BLOCK_UNKNOWN)
5683 REG_BASIC_BLOCK (regno_first) = blocknum;
5684 else if (REG_BASIC_BLOCK (regno_first) != blocknum)
5685 REG_BASIC_BLOCK (regno_first) = REG_BLOCK_GLOBAL;
5687 /* Count (weighted) number of uses of each reg. */
5688 REG_N_REFS (regno_first)
5689 += (optimize_size ? 1 : pbi->bb->loop_depth + 1);
5693 /* Record and count the insns in which a reg dies. If it is used in
5694 this insn and was dead below the insn then it dies in this insn.
5695 If it was set in this insn, we do not make a REG_DEAD note;
5696 likewise if we already made such a note. */
5697 if ((pbi->flags & (PROP_DEATH_NOTES | PROP_REG_INFO))
5701 /* Check for the case where the register dying partially
5702 overlaps the register set by this insn. */
5703 if (regno_first != regno_last)
5704 for (i = regno_first; i <= regno_last; ++i)
5705 some_was_live |= REGNO_REG_SET_P (pbi->new_set, i);
5707 /* If none of the words in X is needed, make a REG_DEAD note.
5708 Otherwise, we must make partial REG_DEAD notes. */
5709 if (! some_was_live)
5711 if ((pbi->flags & PROP_DEATH_NOTES)
5712 && ! find_regno_note (insn, REG_DEAD, regno_first))
5714 = alloc_EXPR_LIST (REG_DEAD, reg, REG_NOTES (insn));
5716 if (pbi->flags & PROP_REG_INFO)
5717 REG_N_DEATHS (regno_first)++;
5721 /* Don't make a REG_DEAD note for a part of a register
5722 that is set in the insn. */
5723 for (i = regno_first; i <= regno_last; ++i)
5724 if (! REGNO_REG_SET_P (pbi->reg_live, i)
5725 && ! dead_or_set_regno_p (insn, i))
5727 = alloc_EXPR_LIST (REG_DEAD,
5728 gen_rtx_REG (reg_raw_mode[i], i),
5733 /* Mark the register as being live. */
5734 for (i = regno_first; i <= regno_last; ++i)
5736 SET_REGNO_REG_SET (pbi->reg_live, i);
5738 #ifdef HAVE_conditional_execution
5739 /* If this is a conditional use, record that fact. If it is later
5740 conditionally set, we'll know to kill the register. */
5741 if (cond != NULL_RTX)
5743 splay_tree_node node;
5744 struct reg_cond_life_info *rcli;
5749 node = splay_tree_lookup (pbi->reg_cond_dead, i);
5752 /* The register was unconditionally live previously.
5753 No need to do anything. */
5757 /* The register was conditionally live previously.
5758 Subtract the new life cond from the old death cond. */
5759 rcli = (struct reg_cond_life_info *) node->value;
5760 ncond = rcli->condition;
5761 ncond = and_reg_cond (ncond, not_reg_cond (cond), 1);
5763 /* If the register is now unconditionally live,
5764 remove the entry in the splay_tree. */
5765 if (ncond == const0_rtx)
5766 splay_tree_remove (pbi->reg_cond_dead, i);
5769 rcli->condition = ncond;
5770 SET_REGNO_REG_SET (pbi->reg_cond_reg,
5771 REGNO (XEXP (cond, 0)));
5777 /* The register was not previously live at all. Record
5778 the condition under which it is still dead. */
5779 rcli = (struct reg_cond_life_info *) xmalloc (sizeof (*rcli));
5780 rcli->condition = not_reg_cond (cond);
5781 rcli->stores = const0_rtx;
5782 rcli->orig_condition = const0_rtx;
5783 splay_tree_insert (pbi->reg_cond_dead, i,
5784 (splay_tree_value) rcli);
5786 SET_REGNO_REG_SET (pbi->reg_cond_reg, REGNO (XEXP (cond, 0)));
5789 else if (some_was_live)
5791 /* The register may have been conditionally live previously, but
5792 is now unconditionally live. Remove it from the conditionally
5793 dead list, so that a conditional set won't cause us to think
5795 splay_tree_remove (pbi->reg_cond_dead, i);
5801 /* Scan expression X and store a 1-bit in NEW_LIVE for each reg it uses.
5802 This is done assuming the registers needed from X are those that
5803 have 1-bits in PBI->REG_LIVE.
5805 INSN is the containing instruction. If INSN is dead, this function
5809 mark_used_regs (pbi, x, cond, insn)
5810 struct propagate_block_info *pbi;
5813 register RTX_CODE code;
5815 int flags = pbi->flags;
5818 code = GET_CODE (x);
5838 /* If we are clobbering a MEM, mark any registers inside the address
5840 if (GET_CODE (XEXP (x, 0)) == MEM)
5841 mark_used_regs (pbi, XEXP (XEXP (x, 0), 0), cond, insn);
5845 /* Don't bother watching stores to mems if this is not the
5846 final pass. We'll not be deleting dead stores this round. */
5847 if (optimize && (flags & PROP_SCAN_DEAD_CODE))
5849 /* Invalidate the data for the last MEM stored, but only if MEM is
5850 something that can be stored into. */
5851 if (GET_CODE (XEXP (x, 0)) == SYMBOL_REF
5852 && CONSTANT_POOL_ADDRESS_P (XEXP (x, 0)))
5853 /* Needn't clear the memory set list. */
5857 rtx temp = pbi->mem_set_list;
5858 rtx prev = NULL_RTX;
5863 next = XEXP (temp, 1);
5864 if (anti_dependence (XEXP (temp, 0), x))
5866 /* Splice temp out of the list. */
5868 XEXP (prev, 1) = next;
5870 pbi->mem_set_list = next;
5871 free_EXPR_LIST_node (temp);
5872 pbi->mem_set_list_len--;
5880 /* If the memory reference had embedded side effects (autoincrement
5881 address modes. Then we may need to kill some entries on the
5884 invalidate_mems_from_autoinc (pbi, insn);
5888 if (flags & PROP_AUTOINC)
5889 find_auto_inc (pbi, x, insn);
5894 #ifdef CLASS_CANNOT_CHANGE_MODE
5895 if (GET_CODE (SUBREG_REG (x)) == REG
5896 && REGNO (SUBREG_REG (x)) >= FIRST_PSEUDO_REGISTER
5897 && CLASS_CANNOT_CHANGE_MODE_P (GET_MODE (x),
5898 GET_MODE (SUBREG_REG (x))))
5899 REG_CHANGES_MODE (REGNO (SUBREG_REG (x))) = 1;
5902 /* While we're here, optimize this case. */
5904 if (GET_CODE (x) != REG)
5909 /* See a register other than being set => mark it as needed. */
5910 mark_used_reg (pbi, x, cond, insn);
5915 register rtx testreg = SET_DEST (x);
5918 /* If storing into MEM, don't show it as being used. But do
5919 show the address as being used. */
5920 if (GET_CODE (testreg) == MEM)
5923 if (flags & PROP_AUTOINC)
5924 find_auto_inc (pbi, testreg, insn);
5926 mark_used_regs (pbi, XEXP (testreg, 0), cond, insn);
5927 mark_used_regs (pbi, SET_SRC (x), cond, insn);
5931 /* Storing in STRICT_LOW_PART is like storing in a reg
5932 in that this SET might be dead, so ignore it in TESTREG.
5933 but in some other ways it is like using the reg.
5935 Storing in a SUBREG or a bit field is like storing the entire
5936 register in that if the register's value is not used
5937 then this SET is not needed. */
5938 while (GET_CODE (testreg) == STRICT_LOW_PART
5939 || GET_CODE (testreg) == ZERO_EXTRACT
5940 || GET_CODE (testreg) == SIGN_EXTRACT
5941 || GET_CODE (testreg) == SUBREG)
5943 #ifdef CLASS_CANNOT_CHANGE_MODE
5944 if (GET_CODE (testreg) == SUBREG
5945 && GET_CODE (SUBREG_REG (testreg)) == REG
5946 && REGNO (SUBREG_REG (testreg)) >= FIRST_PSEUDO_REGISTER
5947 && CLASS_CANNOT_CHANGE_MODE_P (GET_MODE (SUBREG_REG (testreg)),
5948 GET_MODE (testreg)))
5949 REG_CHANGES_MODE (REGNO (SUBREG_REG (testreg))) = 1;
5952 /* Modifying a single register in an alternate mode
5953 does not use any of the old value. But these other
5954 ways of storing in a register do use the old value. */
5955 if (GET_CODE (testreg) == SUBREG
5956 && !(REG_SIZE (SUBREG_REG (testreg)) > REG_SIZE (testreg)))
5961 testreg = XEXP (testreg, 0);
5964 /* If this is a store into a register or group of registers,
5965 recursively scan the value being stored. */
5967 if ((GET_CODE (testreg) == PARALLEL
5968 && GET_MODE (testreg) == BLKmode)
5969 || (GET_CODE (testreg) == REG
5970 && (regno = REGNO (testreg),
5971 ! (regno == FRAME_POINTER_REGNUM
5972 && (! reload_completed || frame_pointer_needed)))
5973 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
5974 && ! (regno == HARD_FRAME_POINTER_REGNUM
5975 && (! reload_completed || frame_pointer_needed))
5977 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
5978 && ! (regno == ARG_POINTER_REGNUM && fixed_regs[regno])
5983 mark_used_regs (pbi, SET_DEST (x), cond, insn);
5984 mark_used_regs (pbi, SET_SRC (x), cond, insn);
5991 case UNSPEC_VOLATILE:
5995 /* Traditional and volatile asm instructions must be considered to use
5996 and clobber all hard registers, all pseudo-registers and all of
5997 memory. So must TRAP_IF and UNSPEC_VOLATILE operations.
5999 Consider for instance a volatile asm that changes the fpu rounding
6000 mode. An insn should not be moved across this even if it only uses
6001 pseudo-regs because it might give an incorrectly rounded result.
6003 ?!? Unfortunately, marking all hard registers as live causes massive
6004 problems for the register allocator and marking all pseudos as live
6005 creates mountains of uninitialized variable warnings.
6007 So for now, just clear the memory set list and mark any regs
6008 we can find in ASM_OPERANDS as used. */
6009 if (code != ASM_OPERANDS || MEM_VOLATILE_P (x))
6011 free_EXPR_LIST_list (&pbi->mem_set_list);
6012 pbi->mem_set_list_len = 0;
6015 /* For all ASM_OPERANDS, we must traverse the vector of input operands.
6016 We can not just fall through here since then we would be confused
6017 by the ASM_INPUT rtx inside ASM_OPERANDS, which do not indicate
6018 traditional asms unlike their normal usage. */
6019 if (code == ASM_OPERANDS)
6023 for (j = 0; j < ASM_OPERANDS_INPUT_LENGTH (x); j++)
6024 mark_used_regs (pbi, ASM_OPERANDS_INPUT (x, j), cond, insn);
6030 if (cond != NULL_RTX)
6033 mark_used_regs (pbi, COND_EXEC_TEST (x), NULL_RTX, insn);
6035 cond = COND_EXEC_TEST (x);
6036 x = COND_EXEC_CODE (x);
6040 /* We _do_not_ want to scan operands of phi nodes. Operands of
6041 a phi function are evaluated only when control reaches this
6042 block along a particular edge. Therefore, regs that appear
6043 as arguments to phi should not be added to the global live at
6051 /* Recursively scan the operands of this expression. */
6054 register const char *fmt = GET_RTX_FORMAT (code);
6057 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
6061 /* Tail recursive case: save a function call level. */
6067 mark_used_regs (pbi, XEXP (x, i), cond, insn);
6069 else if (fmt[i] == 'E')
6072 for (j = 0; j < XVECLEN (x, i); j++)
6073 mark_used_regs (pbi, XVECEXP (x, i, j), cond, insn);
6082 try_pre_increment_1 (pbi, insn)
6083 struct propagate_block_info *pbi;
6086 /* Find the next use of this reg. If in same basic block,
6087 make it do pre-increment or pre-decrement if appropriate. */
6088 rtx x = single_set (insn);
6089 HOST_WIDE_INT amount = ((GET_CODE (SET_SRC (x)) == PLUS ? 1 : -1)
6090 * INTVAL (XEXP (SET_SRC (x), 1)));
6091 int regno = REGNO (SET_DEST (x));
6092 rtx y = pbi->reg_next_use[regno];
6094 && SET_DEST (x) != stack_pointer_rtx
6095 && BLOCK_NUM (y) == BLOCK_NUM (insn)
6096 /* Don't do this if the reg dies, or gets set in y; a standard addressing
6097 mode would be better. */
6098 && ! dead_or_set_p (y, SET_DEST (x))
6099 && try_pre_increment (y, SET_DEST (x), amount))
6101 /* We have found a suitable auto-increment and already changed
6102 insn Y to do it. So flush this increment instruction. */
6103 propagate_block_delete_insn (pbi->bb, insn);
6105 /* Count a reference to this reg for the increment insn we are
6106 deleting. When a reg is incremented, spilling it is worse,
6107 so we want to make that less likely. */
6108 if (regno >= FIRST_PSEUDO_REGISTER)
6110 REG_N_REFS (regno) += (optimize_size ? 1
6111 : pbi->bb->loop_depth + 1);
6112 REG_N_SETS (regno)++;
6115 /* Flush any remembered memories depending on the value of
6116 the incremented register. */
6117 invalidate_mems_from_set (pbi, SET_DEST (x));
6124 /* Try to change INSN so that it does pre-increment or pre-decrement
6125 addressing on register REG in order to add AMOUNT to REG.
6126 AMOUNT is negative for pre-decrement.
6127 Returns 1 if the change could be made.
6128 This checks all about the validity of the result of modifying INSN. */
6131 try_pre_increment (insn, reg, amount)
6133 HOST_WIDE_INT amount;
6137 /* Nonzero if we can try to make a pre-increment or pre-decrement.
6138 For example, addl $4,r1; movl (r1),... can become movl +(r1),... */
6140 /* Nonzero if we can try to make a post-increment or post-decrement.
6141 For example, addl $4,r1; movl -4(r1),... can become movl (r1)+,...
6142 It is possible for both PRE_OK and POST_OK to be nonzero if the machine
6143 supports both pre-inc and post-inc, or both pre-dec and post-dec. */
6146 /* Nonzero if the opportunity actually requires post-inc or post-dec. */
6149 /* From the sign of increment, see which possibilities are conceivable
6150 on this target machine. */
6151 if (HAVE_PRE_INCREMENT && amount > 0)
6153 if (HAVE_POST_INCREMENT && amount > 0)
6156 if (HAVE_PRE_DECREMENT && amount < 0)
6158 if (HAVE_POST_DECREMENT && amount < 0)
6161 if (! (pre_ok || post_ok))
6164 /* It is not safe to add a side effect to a jump insn
6165 because if the incremented register is spilled and must be reloaded
6166 there would be no way to store the incremented value back in memory. */
6168 if (GET_CODE (insn) == JUMP_INSN)
6173 use = find_use_as_address (PATTERN (insn), reg, 0);
6174 if (post_ok && (use == 0 || use == (rtx) 1))
6176 use = find_use_as_address (PATTERN (insn), reg, -amount);
6180 if (use == 0 || use == (rtx) 1)
6183 if (GET_MODE_SIZE (GET_MODE (use)) != (amount > 0 ? amount : - amount))
6186 /* See if this combination of instruction and addressing mode exists. */
6187 if (! validate_change (insn, &XEXP (use, 0),
6188 gen_rtx_fmt_e (amount > 0
6189 ? (do_post ? POST_INC : PRE_INC)
6190 : (do_post ? POST_DEC : PRE_DEC),
6194 /* Record that this insn now has an implicit side effect on X. */
6195 REG_NOTES (insn) = alloc_EXPR_LIST (REG_INC, reg, REG_NOTES (insn));
6199 #endif /* AUTO_INC_DEC */
6201 /* Find the place in the rtx X where REG is used as a memory address.
6202 Return the MEM rtx that so uses it.
6203 If PLUSCONST is nonzero, search instead for a memory address equivalent to
6204 (plus REG (const_int PLUSCONST)).
6206 If such an address does not appear, return 0.
6207 If REG appears more than once, or is used other than in such an address,
6211 find_use_as_address (x, reg, plusconst)
6214 HOST_WIDE_INT plusconst;
6216 enum rtx_code code = GET_CODE (x);
6217 const char *fmt = GET_RTX_FORMAT (code);
6219 register rtx value = 0;
6222 if (code == MEM && XEXP (x, 0) == reg && plusconst == 0)
6225 if (code == MEM && GET_CODE (XEXP (x, 0)) == PLUS
6226 && XEXP (XEXP (x, 0), 0) == reg
6227 && GET_CODE (XEXP (XEXP (x, 0), 1)) == CONST_INT
6228 && INTVAL (XEXP (XEXP (x, 0), 1)) == plusconst)
6231 if (code == SIGN_EXTRACT || code == ZERO_EXTRACT)
6233 /* If REG occurs inside a MEM used in a bit-field reference,
6234 that is unacceptable. */
6235 if (find_use_as_address (XEXP (x, 0), reg, 0) != 0)
6236 return (rtx) (HOST_WIDE_INT) 1;
6240 return (rtx) (HOST_WIDE_INT) 1;
6242 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
6246 tem = find_use_as_address (XEXP (x, i), reg, plusconst);
6250 return (rtx) (HOST_WIDE_INT) 1;
6252 else if (fmt[i] == 'E')
6255 for (j = XVECLEN (x, i) - 1; j >= 0; j--)
6257 tem = find_use_as_address (XVECEXP (x, i, j), reg, plusconst);
6261 return (rtx) (HOST_WIDE_INT) 1;
6269 /* Write information about registers and basic blocks into FILE.
6270 This is part of making a debugging dump. */
6273 dump_regset (r, outf)
6280 fputs (" (nil)", outf);
6284 EXECUTE_IF_SET_IN_REG_SET (r, 0, i,
6286 fprintf (outf, " %d", i);
6287 if (i < FIRST_PSEUDO_REGISTER)
6288 fprintf (outf, " [%s]",
6293 /* Print a human-reaable representation of R on the standard error
6294 stream. This function is designed to be used from within the
6301 dump_regset (r, stderr);
6302 putc ('\n', stderr);
6306 dump_flow_info (file)
6310 static const char * const reg_class_names[] = REG_CLASS_NAMES;
6312 fprintf (file, "%d registers.\n", max_regno);
6313 for (i = FIRST_PSEUDO_REGISTER; i < max_regno; i++)
6316 enum reg_class class, altclass;
6317 fprintf (file, "\nRegister %d used %d times across %d insns",
6318 i, REG_N_REFS (i), REG_LIVE_LENGTH (i));
6319 if (REG_BASIC_BLOCK (i) >= 0)
6320 fprintf (file, " in block %d", REG_BASIC_BLOCK (i));
6322 fprintf (file, "; set %d time%s", REG_N_SETS (i),
6323 (REG_N_SETS (i) == 1) ? "" : "s");
6324 if (REG_USERVAR_P (regno_reg_rtx[i]))
6325 fprintf (file, "; user var");
6326 if (REG_N_DEATHS (i) != 1)
6327 fprintf (file, "; dies in %d places", REG_N_DEATHS (i));
6328 if (REG_N_CALLS_CROSSED (i) == 1)
6329 fprintf (file, "; crosses 1 call");
6330 else if (REG_N_CALLS_CROSSED (i))
6331 fprintf (file, "; crosses %d calls", REG_N_CALLS_CROSSED (i));
6332 if (PSEUDO_REGNO_BYTES (i) != UNITS_PER_WORD)
6333 fprintf (file, "; %d bytes", PSEUDO_REGNO_BYTES (i));
6334 class = reg_preferred_class (i);
6335 altclass = reg_alternate_class (i);
6336 if (class != GENERAL_REGS || altclass != ALL_REGS)
6338 if (altclass == ALL_REGS || class == ALL_REGS)
6339 fprintf (file, "; pref %s", reg_class_names[(int) class]);
6340 else if (altclass == NO_REGS)
6341 fprintf (file, "; %s or none", reg_class_names[(int) class]);
6343 fprintf (file, "; pref %s, else %s",
6344 reg_class_names[(int) class],
6345 reg_class_names[(int) altclass]);
6347 if (REG_POINTER (regno_reg_rtx[i]))
6348 fprintf (file, "; pointer");
6349 fprintf (file, ".\n");
6352 fprintf (file, "\n%d basic blocks, %d edges.\n", n_basic_blocks, n_edges);
6353 for (i = 0; i < n_basic_blocks; i++)
6355 register basic_block bb = BASIC_BLOCK (i);
6358 fprintf (file, "\nBasic block %d: first insn %d, last %d, loop_depth %d, count %d.\n",
6359 i, INSN_UID (bb->head), INSN_UID (bb->end), bb->loop_depth, bb->count);
6361 fprintf (file, "Predecessors: ");
6362 for (e = bb->pred; e; e = e->pred_next)
6363 dump_edge_info (file, e, 0);
6365 fprintf (file, "\nSuccessors: ");
6366 for (e = bb->succ; e; e = e->succ_next)
6367 dump_edge_info (file, e, 1);
6369 fprintf (file, "\nRegisters live at start:");
6370 dump_regset (bb->global_live_at_start, file);
6372 fprintf (file, "\nRegisters live at end:");
6373 dump_regset (bb->global_live_at_end, file);
6384 dump_flow_info (stderr);
6388 dump_edge_info (file, e, do_succ)
6393 basic_block side = (do_succ ? e->dest : e->src);
6395 if (side == ENTRY_BLOCK_PTR)
6396 fputs (" ENTRY", file);
6397 else if (side == EXIT_BLOCK_PTR)
6398 fputs (" EXIT", file);
6400 fprintf (file, " %d", side->index);
6403 fprintf (file, " count:%d", e->count);
6407 static const char * const bitnames[] = {
6408 "fallthru", "crit", "ab", "abcall", "eh", "fake"
6411 int i, flags = e->flags;
6415 for (i = 0; flags; i++)
6416 if (flags & (1 << i))
6422 if (i < (int) ARRAY_SIZE (bitnames))
6423 fputs (bitnames[i], file);
6425 fprintf (file, "%d", i);
6432 /* Print out one basic block with live information at start and end. */
6443 fprintf (outf, ";; Basic block %d, loop depth %d, count %d",
6444 bb->index, bb->loop_depth, bb->count);
6447 fputs (";; Predecessors: ", outf);
6448 for (e = bb->pred; e; e = e->pred_next)
6449 dump_edge_info (outf, e, 0);
6452 fputs (";; Registers live at start:", outf);
6453 dump_regset (bb->global_live_at_start, outf);
6456 for (insn = bb->head, last = NEXT_INSN (bb->end);
6458 insn = NEXT_INSN (insn))
6459 print_rtl_single (outf, insn);
6461 fputs (";; Registers live at end:", outf);
6462 dump_regset (bb->global_live_at_end, outf);
6465 fputs (";; Successors: ", outf);
6466 for (e = bb->succ; e; e = e->succ_next)
6467 dump_edge_info (outf, e, 1);
6475 dump_bb (bb, stderr);
6482 dump_bb (BASIC_BLOCK (n), stderr);
6485 /* Like print_rtl, but also print out live information for the start of each
6489 print_rtl_with_bb (outf, rtx_first)
6493 register rtx tmp_rtx;
6496 fprintf (outf, "(nil)\n");
6500 enum bb_state { NOT_IN_BB, IN_ONE_BB, IN_MULTIPLE_BB };
6501 int max_uid = get_max_uid ();
6502 basic_block *start = (basic_block *)
6503 xcalloc (max_uid, sizeof (basic_block));
6504 basic_block *end = (basic_block *)
6505 xcalloc (max_uid, sizeof (basic_block));
6506 enum bb_state *in_bb_p = (enum bb_state *)
6507 xcalloc (max_uid, sizeof (enum bb_state));
6509 for (i = n_basic_blocks - 1; i >= 0; i--)
6511 basic_block bb = BASIC_BLOCK (i);
6514 start[INSN_UID (bb->head)] = bb;
6515 end[INSN_UID (bb->end)] = bb;
6516 for (x = bb->head; x != NULL_RTX; x = NEXT_INSN (x))
6518 enum bb_state state = IN_MULTIPLE_BB;
6519 if (in_bb_p[INSN_UID (x)] == NOT_IN_BB)
6521 in_bb_p[INSN_UID (x)] = state;
6528 for (tmp_rtx = rtx_first; NULL != tmp_rtx; tmp_rtx = NEXT_INSN (tmp_rtx))
6533 if ((bb = start[INSN_UID (tmp_rtx)]) != NULL)
6535 fprintf (outf, ";; Start of basic block %d, registers live:",
6537 dump_regset (bb->global_live_at_start, outf);
6541 if (in_bb_p[INSN_UID (tmp_rtx)] == NOT_IN_BB
6542 && GET_CODE (tmp_rtx) != NOTE
6543 && GET_CODE (tmp_rtx) != BARRIER)
6544 fprintf (outf, ";; Insn is not within a basic block\n");
6545 else if (in_bb_p[INSN_UID (tmp_rtx)] == IN_MULTIPLE_BB)
6546 fprintf (outf, ";; Insn is in multiple basic blocks\n");
6548 did_output = print_rtl_single (outf, tmp_rtx);
6550 if ((bb = end[INSN_UID (tmp_rtx)]) != NULL)
6552 fprintf (outf, ";; End of basic block %d, registers live:\n",
6554 dump_regset (bb->global_live_at_end, outf);
6567 if (current_function_epilogue_delay_list != 0)
6569 fprintf (outf, "\n;; Insns in epilogue delay list:\n\n");
6570 for (tmp_rtx = current_function_epilogue_delay_list; tmp_rtx != 0;
6571 tmp_rtx = XEXP (tmp_rtx, 1))
6572 print_rtl_single (outf, XEXP (tmp_rtx, 0));
6576 /* Dump the rtl into the current debugging dump file, then abort. */
6579 print_rtl_and_abort_fcn (file, line, function)
6582 const char *function;
6586 print_rtl_with_bb (rtl_dump_file, get_insns ());
6587 fclose (rtl_dump_file);
6590 fancy_abort (file, line, function);
6593 /* Recompute register set/reference counts immediately prior to register
6596 This avoids problems with set/reference counts changing to/from values
6597 which have special meanings to the register allocators.
6599 Additionally, the reference counts are the primary component used by the
6600 register allocators to prioritize pseudos for allocation to hard regs.
6601 More accurate reference counts generally lead to better register allocation.
6603 F is the first insn to be scanned.
6605 LOOP_STEP denotes how much loop_depth should be incremented per
6606 loop nesting level in order to increase the ref count more for
6607 references in a loop.
6609 It might be worthwhile to update REG_LIVE_LENGTH, REG_BASIC_BLOCK and
6610 possibly other information which is used by the register allocators. */
6613 recompute_reg_usage (f, loop_step)
6614 rtx f ATTRIBUTE_UNUSED;
6615 int loop_step ATTRIBUTE_UNUSED;
6617 allocate_reg_life_data ();
6618 update_life_info (NULL, UPDATE_LIFE_LOCAL, PROP_REG_INFO);
6621 /* Optionally removes all the REG_DEAD and REG_UNUSED notes from a set of
6622 blocks. If BLOCKS is NULL, assume the universal set. Returns a count
6623 of the number of registers that died. */
6626 count_or_remove_death_notes (blocks, kill)
6632 for (i = n_basic_blocks - 1; i >= 0; --i)
6637 if (blocks && ! TEST_BIT (blocks, i))
6640 bb = BASIC_BLOCK (i);
6642 for (insn = bb->head;; insn = NEXT_INSN (insn))
6646 rtx *pprev = ®_NOTES (insn);
6651 switch (REG_NOTE_KIND (link))
6654 if (GET_CODE (XEXP (link, 0)) == REG)
6656 rtx reg = XEXP (link, 0);
6659 if (REGNO (reg) >= FIRST_PSEUDO_REGISTER)
6662 n = HARD_REGNO_NREGS (REGNO (reg), GET_MODE (reg));
6670 rtx next = XEXP (link, 1);
6671 free_EXPR_LIST_node (link);
6672 *pprev = link = next;
6678 pprev = &XEXP (link, 1);
6685 if (insn == bb->end)
6694 /* Update insns block within BB. */
6697 update_bb_for_insn (bb)
6702 if (! basic_block_for_insn)
6705 for (insn = bb->head; ; insn = NEXT_INSN (insn))
6707 set_block_for_insn (insn, bb);
6709 if (insn == bb->end)
6715 /* Record INSN's block as BB. */
6718 set_block_for_insn (insn, bb)
6722 size_t uid = INSN_UID (insn);
6723 if (uid >= basic_block_for_insn->num_elements)
6727 /* Add one-eighth the size so we don't keep calling xrealloc. */
6728 new_size = uid + (uid + 7) / 8;
6730 VARRAY_GROW (basic_block_for_insn, new_size);
6732 VARRAY_BB (basic_block_for_insn, uid) = bb;
6735 /* When a new insn has been inserted into an existing block, it will
6736 sometimes emit more than a single insn. This routine will set the
6737 block number for the specified insn, and look backwards in the insn
6738 chain to see if there are any other uninitialized insns immediately
6739 previous to this one, and set the block number for them too. */
6742 set_block_for_new_insns (insn, bb)
6746 set_block_for_insn (insn, bb);
6748 /* Scan the previous instructions setting the block number until we find
6749 an instruction that has the block number set, or we find a note
6751 for (insn = PREV_INSN (insn); insn != NULL_RTX; insn = PREV_INSN (insn))
6753 if (GET_CODE (insn) == NOTE)
6755 if (INSN_UID (insn) >= basic_block_for_insn->num_elements
6756 || BLOCK_FOR_INSN (insn) == 0)
6757 set_block_for_insn (insn, bb);
6763 /* Verify the CFG consistency. This function check some CFG invariants and
6764 aborts when something is wrong. Hope that this function will help to
6765 convert many optimization passes to preserve CFG consistent.
6767 Currently it does following checks:
6769 - test head/end pointers
6770 - overlapping of basic blocks
6771 - edge list corectness
6772 - headers of basic blocks (the NOTE_INSN_BASIC_BLOCK note)
6773 - tails of basic blocks (ensure that boundary is necesary)
6774 - scans body of the basic block for JUMP_INSN, CODE_LABEL
6775 and NOTE_INSN_BASIC_BLOCK
6776 - check that all insns are in the basic blocks
6777 (except the switch handling code, barriers and notes)
6778 - check that all returns are followed by barriers
6780 In future it can be extended check a lot of other stuff as well
6781 (reachability of basic blocks, life information, etc. etc.). */
6786 const int max_uid = get_max_uid ();
6787 const rtx rtx_first = get_insns ();
6788 rtx last_head = get_last_insn ();
6789 basic_block *bb_info;
6791 int i, last_bb_num_seen, num_bb_notes, err = 0;
6793 bb_info = (basic_block *) xcalloc (max_uid, sizeof (basic_block));
6795 for (i = n_basic_blocks - 1; i >= 0; i--)
6797 basic_block bb = BASIC_BLOCK (i);
6798 rtx head = bb->head;
6801 /* Verify the end of the basic block is in the INSN chain. */
6802 for (x = last_head; x != NULL_RTX; x = PREV_INSN (x))
6807 error ("End insn %d for block %d not found in the insn stream.",
6808 INSN_UID (end), bb->index);
6812 /* Work backwards from the end to the head of the basic block
6813 to verify the head is in the RTL chain. */
6814 for (; x != NULL_RTX; x = PREV_INSN (x))
6816 /* While walking over the insn chain, verify insns appear
6817 in only one basic block and initialize the BB_INFO array
6818 used by other passes. */
6819 if (bb_info[INSN_UID (x)] != NULL)
6821 error ("Insn %d is in multiple basic blocks (%d and %d)",
6822 INSN_UID (x), bb->index, bb_info[INSN_UID (x)]->index);
6825 bb_info[INSN_UID (x)] = bb;
6832 error ("Head insn %d for block %d not found in the insn stream.",
6833 INSN_UID (head), bb->index);
6840 /* Now check the basic blocks (boundaries etc.) */
6841 for (i = n_basic_blocks - 1; i >= 0; i--)
6843 basic_block bb = BASIC_BLOCK (i);
6844 /* Check corectness of edge lists */
6853 "verify_flow_info: Basic block %d succ edge is corrupted\n",
6855 fprintf (stderr, "Predecessor: ");
6856 dump_edge_info (stderr, e, 0);
6857 fprintf (stderr, "\nSuccessor: ");
6858 dump_edge_info (stderr, e, 1);
6862 if (e->dest != EXIT_BLOCK_PTR)
6864 edge e2 = e->dest->pred;
6865 while (e2 && e2 != e)
6869 error ("Basic block %i edge lists are corrupted", bb->index);
6881 error ("Basic block %d pred edge is corrupted", bb->index);
6882 fputs ("Predecessor: ", stderr);
6883 dump_edge_info (stderr, e, 0);
6884 fputs ("\nSuccessor: ", stderr);
6885 dump_edge_info (stderr, e, 1);
6886 fputc ('\n', stderr);
6889 if (e->src != ENTRY_BLOCK_PTR)
6891 edge e2 = e->src->succ;
6892 while (e2 && e2 != e)
6896 error ("Basic block %i edge lists are corrupted", bb->index);
6903 /* OK pointers are correct. Now check the header of basic
6904 block. It ought to contain optional CODE_LABEL followed
6905 by NOTE_BASIC_BLOCK. */
6907 if (GET_CODE (x) == CODE_LABEL)
6911 error ("NOTE_INSN_BASIC_BLOCK is missing for block %d",
6917 if (!NOTE_INSN_BASIC_BLOCK_P (x) || NOTE_BASIC_BLOCK (x) != bb)
6919 error ("NOTE_INSN_BASIC_BLOCK is missing for block %d\n",
6926 /* Do checks for empty blocks here */
6933 if (NOTE_INSN_BASIC_BLOCK_P (x))
6935 error ("NOTE_INSN_BASIC_BLOCK %d in the middle of basic block %d",
6936 INSN_UID (x), bb->index);
6943 if (GET_CODE (x) == JUMP_INSN
6944 || GET_CODE (x) == CODE_LABEL
6945 || GET_CODE (x) == BARRIER)
6947 error ("In basic block %d:", bb->index);
6948 fatal_insn ("Flow control insn inside a basic block", x);
6956 last_bb_num_seen = -1;
6961 if (NOTE_INSN_BASIC_BLOCK_P (x))
6963 basic_block bb = NOTE_BASIC_BLOCK (x);
6965 if (bb->index != last_bb_num_seen + 1)
6966 /* Basic blocks not numbered consecutively. */
6969 last_bb_num_seen = bb->index;
6972 if (!bb_info[INSN_UID (x)])
6974 switch (GET_CODE (x))
6981 /* An addr_vec is placed outside any block block. */
6983 && GET_CODE (NEXT_INSN (x)) == JUMP_INSN
6984 && (GET_CODE (PATTERN (NEXT_INSN (x))) == ADDR_DIFF_VEC
6985 || GET_CODE (PATTERN (NEXT_INSN (x))) == ADDR_VEC))
6990 /* But in any case, non-deletable labels can appear anywhere. */
6994 fatal_insn ("Insn outside basic block", x);
6999 && GET_CODE (x) == JUMP_INSN
7000 && returnjump_p (x) && ! condjump_p (x)
7001 && ! (NEXT_INSN (x) && GET_CODE (NEXT_INSN (x)) == BARRIER))
7002 fatal_insn ("Return not followed by barrier", x);
7007 if (num_bb_notes != n_basic_blocks)
7009 ("number of bb notes in insn chain (%d) != n_basic_blocks (%d)",
7010 num_bb_notes, n_basic_blocks);
7019 /* Functions to access an edge list with a vector representation.
7020 Enough data is kept such that given an index number, the
7021 pred and succ that edge represents can be determined, or
7022 given a pred and a succ, its index number can be returned.
7023 This allows algorithms which consume a lot of memory to
7024 represent the normally full matrix of edge (pred,succ) with a
7025 single indexed vector, edge (EDGE_INDEX (pred, succ)), with no
7026 wasted space in the client code due to sparse flow graphs. */
7028 /* This functions initializes the edge list. Basically the entire
7029 flowgraph is processed, and all edges are assigned a number,
7030 and the data structure is filled in. */
7035 struct edge_list *elist;
7041 block_count = n_basic_blocks + 2; /* Include the entry and exit blocks. */
7045 /* Determine the number of edges in the flow graph by counting successor
7046 edges on each basic block. */
7047 for (x = 0; x < n_basic_blocks; x++)
7049 basic_block bb = BASIC_BLOCK (x);
7051 for (e = bb->succ; e; e = e->succ_next)
7054 /* Don't forget successors of the entry block. */
7055 for (e = ENTRY_BLOCK_PTR->succ; e; e = e->succ_next)
7058 elist = (struct edge_list *) xmalloc (sizeof (struct edge_list));
7059 elist->num_blocks = block_count;
7060 elist->num_edges = num_edges;
7061 elist->index_to_edge = (edge *) xmalloc (sizeof (edge) * num_edges);
7065 /* Follow successors of the entry block, and register these edges. */
7066 for (e = ENTRY_BLOCK_PTR->succ; e; e = e->succ_next)
7068 elist->index_to_edge[num_edges] = e;
7072 for (x = 0; x < n_basic_blocks; x++)
7074 basic_block bb = BASIC_BLOCK (x);
7076 /* Follow all successors of blocks, and register these edges. */
7077 for (e = bb->succ; e; e = e->succ_next)
7079 elist->index_to_edge[num_edges] = e;
7086 /* This function free's memory associated with an edge list. */
7089 free_edge_list (elist)
7090 struct edge_list *elist;
7094 free (elist->index_to_edge);
7099 /* This function provides debug output showing an edge list. */
7102 print_edge_list (f, elist)
7104 struct edge_list *elist;
7107 fprintf (f, "Compressed edge list, %d BBs + entry & exit, and %d edges\n",
7108 elist->num_blocks - 2, elist->num_edges);
7110 for (x = 0; x < elist->num_edges; x++)
7112 fprintf (f, " %-4d - edge(", x);
7113 if (INDEX_EDGE_PRED_BB (elist, x) == ENTRY_BLOCK_PTR)
7114 fprintf (f, "entry,");
7116 fprintf (f, "%d,", INDEX_EDGE_PRED_BB (elist, x)->index);
7118 if (INDEX_EDGE_SUCC_BB (elist, x) == EXIT_BLOCK_PTR)
7119 fprintf (f, "exit)\n");
7121 fprintf (f, "%d)\n", INDEX_EDGE_SUCC_BB (elist, x)->index);
7125 /* This function provides an internal consistency check of an edge list,
7126 verifying that all edges are present, and that there are no
7130 verify_edge_list (f, elist)
7132 struct edge_list *elist;
7134 int x, pred, succ, index;
7137 for (x = 0; x < n_basic_blocks; x++)
7139 basic_block bb = BASIC_BLOCK (x);
7141 for (e = bb->succ; e; e = e->succ_next)
7143 pred = e->src->index;
7144 succ = e->dest->index;
7145 index = EDGE_INDEX (elist, e->src, e->dest);
7146 if (index == EDGE_INDEX_NO_EDGE)
7148 fprintf (f, "*p* No index for edge from %d to %d\n", pred, succ);
7151 if (INDEX_EDGE_PRED_BB (elist, index)->index != pred)
7152 fprintf (f, "*p* Pred for index %d should be %d not %d\n",
7153 index, pred, INDEX_EDGE_PRED_BB (elist, index)->index);
7154 if (INDEX_EDGE_SUCC_BB (elist, index)->index != succ)
7155 fprintf (f, "*p* Succ for index %d should be %d not %d\n",
7156 index, succ, INDEX_EDGE_SUCC_BB (elist, index)->index);
7159 for (e = ENTRY_BLOCK_PTR->succ; e; e = e->succ_next)
7161 pred = e->src->index;
7162 succ = e->dest->index;
7163 index = EDGE_INDEX (elist, e->src, e->dest);
7164 if (index == EDGE_INDEX_NO_EDGE)
7166 fprintf (f, "*p* No index for edge from %d to %d\n", pred, succ);
7169 if (INDEX_EDGE_PRED_BB (elist, index)->index != pred)
7170 fprintf (f, "*p* Pred for index %d should be %d not %d\n",
7171 index, pred, INDEX_EDGE_PRED_BB (elist, index)->index);
7172 if (INDEX_EDGE_SUCC_BB (elist, index)->index != succ)
7173 fprintf (f, "*p* Succ for index %d should be %d not %d\n",
7174 index, succ, INDEX_EDGE_SUCC_BB (elist, index)->index);
7176 /* We've verified that all the edges are in the list, no lets make sure
7177 there are no spurious edges in the list. */
7179 for (pred = 0; pred < n_basic_blocks; pred++)
7180 for (succ = 0; succ < n_basic_blocks; succ++)
7182 basic_block p = BASIC_BLOCK (pred);
7183 basic_block s = BASIC_BLOCK (succ);
7187 for (e = p->succ; e; e = e->succ_next)
7193 for (e = s->pred; e; e = e->pred_next)
7199 if (EDGE_INDEX (elist, BASIC_BLOCK (pred), BASIC_BLOCK (succ))
7200 == EDGE_INDEX_NO_EDGE && found_edge != 0)
7201 fprintf (f, "*** Edge (%d, %d) appears to not have an index\n",
7203 if (EDGE_INDEX (elist, BASIC_BLOCK (pred), BASIC_BLOCK (succ))
7204 != EDGE_INDEX_NO_EDGE && found_edge == 0)
7205 fprintf (f, "*** Edge (%d, %d) has index %d, but there is no edge\n",
7206 pred, succ, EDGE_INDEX (elist, BASIC_BLOCK (pred),
7207 BASIC_BLOCK (succ)));
7209 for (succ = 0; succ < n_basic_blocks; succ++)
7211 basic_block p = ENTRY_BLOCK_PTR;
7212 basic_block s = BASIC_BLOCK (succ);
7216 for (e = p->succ; e; e = e->succ_next)
7222 for (e = s->pred; e; e = e->pred_next)
7228 if (EDGE_INDEX (elist, ENTRY_BLOCK_PTR, BASIC_BLOCK (succ))
7229 == EDGE_INDEX_NO_EDGE && found_edge != 0)
7230 fprintf (f, "*** Edge (entry, %d) appears to not have an index\n",
7232 if (EDGE_INDEX (elist, ENTRY_BLOCK_PTR, BASIC_BLOCK (succ))
7233 != EDGE_INDEX_NO_EDGE && found_edge == 0)
7234 fprintf (f, "*** Edge (entry, %d) has index %d, but no edge exists\n",
7235 succ, EDGE_INDEX (elist, ENTRY_BLOCK_PTR,
7236 BASIC_BLOCK (succ)));
7238 for (pred = 0; pred < n_basic_blocks; pred++)
7240 basic_block p = BASIC_BLOCK (pred);
7241 basic_block s = EXIT_BLOCK_PTR;
7245 for (e = p->succ; e; e = e->succ_next)
7251 for (e = s->pred; e; e = e->pred_next)
7257 if (EDGE_INDEX (elist, BASIC_BLOCK (pred), EXIT_BLOCK_PTR)
7258 == EDGE_INDEX_NO_EDGE && found_edge != 0)
7259 fprintf (f, "*** Edge (%d, exit) appears to not have an index\n",
7261 if (EDGE_INDEX (elist, BASIC_BLOCK (pred), EXIT_BLOCK_PTR)
7262 != EDGE_INDEX_NO_EDGE && found_edge == 0)
7263 fprintf (f, "*** Edge (%d, exit) has index %d, but no edge exists\n",
7264 pred, EDGE_INDEX (elist, BASIC_BLOCK (pred),
7269 /* This routine will determine what, if any, edge there is between
7270 a specified predecessor and successor. */
7273 find_edge_index (edge_list, pred, succ)
7274 struct edge_list *edge_list;
7275 basic_block pred, succ;
7278 for (x = 0; x < NUM_EDGES (edge_list); x++)
7280 if (INDEX_EDGE_PRED_BB (edge_list, x) == pred
7281 && INDEX_EDGE_SUCC_BB (edge_list, x) == succ)
7284 return (EDGE_INDEX_NO_EDGE);
7287 /* This function will remove an edge from the flow graph. */
7293 edge last_pred = NULL;
7294 edge last_succ = NULL;
7296 basic_block src, dest;
7299 for (tmp = src->succ; tmp && tmp != e; tmp = tmp->succ_next)
7305 last_succ->succ_next = e->succ_next;
7307 src->succ = e->succ_next;
7309 for (tmp = dest->pred; tmp && tmp != e; tmp = tmp->pred_next)
7315 last_pred->pred_next = e->pred_next;
7317 dest->pred = e->pred_next;
7323 /* This routine will remove any fake successor edges for a basic block.
7324 When the edge is removed, it is also removed from whatever predecessor
7328 remove_fake_successors (bb)
7332 for (e = bb->succ; e;)
7336 if ((tmp->flags & EDGE_FAKE) == EDGE_FAKE)
7341 /* This routine will remove all fake edges from the flow graph. If
7342 we remove all fake successors, it will automatically remove all
7343 fake predecessors. */
7346 remove_fake_edges ()
7350 for (x = 0; x < n_basic_blocks; x++)
7351 remove_fake_successors (BASIC_BLOCK (x));
7353 /* We've handled all successors except the entry block's. */
7354 remove_fake_successors (ENTRY_BLOCK_PTR);
7357 /* This function will add a fake edge between any block which has no
7358 successors, and the exit block. Some data flow equations require these
7362 add_noreturn_fake_exit_edges ()
7366 for (x = 0; x < n_basic_blocks; x++)
7367 if (BASIC_BLOCK (x)->succ == NULL)
7368 make_edge (NULL, BASIC_BLOCK (x), EXIT_BLOCK_PTR, EDGE_FAKE);
7371 /* This function adds a fake edge between any infinite loops to the
7372 exit block. Some optimizations require a path from each node to
7375 See also Morgan, Figure 3.10, pp. 82-83.
7377 The current implementation is ugly, not attempting to minimize the
7378 number of inserted fake edges. To reduce the number of fake edges
7379 to insert, add fake edges from _innermost_ loops containing only
7380 nodes not reachable from the exit block. */
7383 connect_infinite_loops_to_exit ()
7385 basic_block unvisited_block;
7387 /* Perform depth-first search in the reverse graph to find nodes
7388 reachable from the exit block. */
7389 struct depth_first_search_dsS dfs_ds;
7391 flow_dfs_compute_reverse_init (&dfs_ds);
7392 flow_dfs_compute_reverse_add_bb (&dfs_ds, EXIT_BLOCK_PTR);
7394 /* Repeatedly add fake edges, updating the unreachable nodes. */
7397 unvisited_block = flow_dfs_compute_reverse_execute (&dfs_ds);
7398 if (!unvisited_block)
7400 make_edge (NULL, unvisited_block, EXIT_BLOCK_PTR, EDGE_FAKE);
7401 flow_dfs_compute_reverse_add_bb (&dfs_ds, unvisited_block);
7404 flow_dfs_compute_reverse_finish (&dfs_ds);
7409 /* Redirect an edge's successor from one block to another. */
7412 redirect_edge_succ (e, new_succ)
7414 basic_block new_succ;
7418 /* Disconnect the edge from the old successor block. */
7419 for (pe = &e->dest->pred; *pe != e; pe = &(*pe)->pred_next)
7421 *pe = (*pe)->pred_next;
7423 /* Reconnect the edge to the new successor block. */
7424 e->pred_next = new_succ->pred;
7429 /* Redirect an edge's predecessor from one block to another. */
7432 redirect_edge_pred (e, new_pred)
7434 basic_block new_pred;
7438 /* Disconnect the edge from the old predecessor block. */
7439 for (pe = &e->src->succ; *pe != e; pe = &(*pe)->succ_next)
7441 *pe = (*pe)->succ_next;
7443 /* Reconnect the edge to the new predecessor block. */
7444 e->succ_next = new_pred->succ;
7449 /* Dump the list of basic blocks in the bitmap NODES. */
7452 flow_nodes_print (str, nodes, file)
7454 const sbitmap nodes;
7462 fprintf (file, "%s { ", str);
7463 EXECUTE_IF_SET_IN_SBITMAP (nodes, 0, node, {fprintf (file, "%d ", node);});
7464 fputs ("}\n", file);
7468 /* Dump the list of edges in the array EDGE_LIST. */
7471 flow_edge_list_print (str, edge_list, num_edges, file)
7473 const edge *edge_list;
7482 fprintf (file, "%s { ", str);
7483 for (i = 0; i < num_edges; i++)
7484 fprintf (file, "%d->%d ", edge_list[i]->src->index,
7485 edge_list[i]->dest->index);
7486 fputs ("}\n", file);
7490 /* Dump loop related CFG information. */
7493 flow_loops_cfg_dump (loops, file)
7494 const struct loops *loops;
7499 if (! loops->num || ! file || ! loops->cfg.dom)
7502 for (i = 0; i < n_basic_blocks; i++)
7506 fprintf (file, ";; %d succs { ", i);
7507 for (succ = BASIC_BLOCK (i)->succ; succ; succ = succ->succ_next)
7508 fprintf (file, "%d ", succ->dest->index);
7509 flow_nodes_print ("} dom", loops->cfg.dom[i], file);
7512 /* Dump the DFS node order. */
7513 if (loops->cfg.dfs_order)
7515 fputs (";; DFS order: ", file);
7516 for (i = 0; i < n_basic_blocks; i++)
7517 fprintf (file, "%d ", loops->cfg.dfs_order[i]);
7520 /* Dump the reverse completion node order. */
7521 if (loops->cfg.rc_order)
7523 fputs (";; RC order: ", file);
7524 for (i = 0; i < n_basic_blocks; i++)
7525 fprintf (file, "%d ", loops->cfg.rc_order[i]);
7530 /* Return non-zero if the nodes of LOOP are a subset of OUTER. */
7533 flow_loop_nested_p (outer, loop)
7537 return sbitmap_a_subset_b_p (loop->nodes, outer->nodes);
7541 /* Dump the loop information specified by LOOP to the stream FILE
7542 using auxiliary dump callback function LOOP_DUMP_AUX if non null. */
7544 flow_loop_dump (loop, file, loop_dump_aux, verbose)
7545 const struct loop *loop;
7547 void (*loop_dump_aux) PARAMS((const struct loop *, FILE *, int));
7550 if (! loop || ! loop->header)
7553 fprintf (file, ";;\n;; Loop %d (%d to %d):%s%s\n",
7554 loop->num, INSN_UID (loop->first->head),
7555 INSN_UID (loop->last->end),
7556 loop->shared ? " shared" : "",
7557 loop->invalid ? " invalid" : "");
7558 fprintf (file, ";; header %d, latch %d, pre-header %d, first %d, last %d\n",
7559 loop->header->index, loop->latch->index,
7560 loop->pre_header ? loop->pre_header->index : -1,
7561 loop->first->index, loop->last->index);
7562 fprintf (file, ";; depth %d, level %d, outer %ld\n",
7563 loop->depth, loop->level,
7564 (long) (loop->outer ? loop->outer->num : -1));
7566 if (loop->pre_header_edges)
7567 flow_edge_list_print (";; pre-header edges", loop->pre_header_edges,
7568 loop->num_pre_header_edges, file);
7569 flow_edge_list_print (";; entry edges", loop->entry_edges,
7570 loop->num_entries, file);
7571 fprintf (file, ";; %d", loop->num_nodes);
7572 flow_nodes_print (" nodes", loop->nodes, file);
7573 flow_edge_list_print (";; exit edges", loop->exit_edges,
7574 loop->num_exits, file);
7575 if (loop->exits_doms)
7576 flow_nodes_print (";; exit doms", loop->exits_doms, file);
7578 loop_dump_aux (loop, file, verbose);
7582 /* Dump the loop information specified by LOOPS to the stream FILE,
7583 using auxiliary dump callback function LOOP_DUMP_AUX if non null. */
7585 flow_loops_dump (loops, file, loop_dump_aux, verbose)
7586 const struct loops *loops;
7588 void (*loop_dump_aux) PARAMS((const struct loop *, FILE *, int));
7594 num_loops = loops->num;
7595 if (! num_loops || ! file)
7598 fprintf (file, ";; %d loops found, %d levels\n",
7599 num_loops, loops->levels);
7601 for (i = 0; i < num_loops; i++)
7603 struct loop *loop = &loops->array[i];
7605 flow_loop_dump (loop, file, loop_dump_aux, verbose);
7611 for (j = 0; j < i; j++)
7613 struct loop *oloop = &loops->array[j];
7615 if (loop->header == oloop->header)
7620 smaller = loop->num_nodes < oloop->num_nodes;
7622 /* If the union of LOOP and OLOOP is different than
7623 the larger of LOOP and OLOOP then LOOP and OLOOP
7624 must be disjoint. */
7625 disjoint = ! flow_loop_nested_p (smaller ? loop : oloop,
7626 smaller ? oloop : loop);
7628 ";; loop header %d shared by loops %d, %d %s\n",
7629 loop->header->index, i, j,
7630 disjoint ? "disjoint" : "nested");
7637 flow_loops_cfg_dump (loops, file);
7641 /* Free all the memory allocated for LOOPS. */
7644 flow_loops_free (loops)
7645 struct loops *loops;
7654 /* Free the loop descriptors. */
7655 for (i = 0; i < loops->num; i++)
7657 struct loop *loop = &loops->array[i];
7659 if (loop->pre_header_edges)
7660 free (loop->pre_header_edges);
7662 sbitmap_free (loop->nodes);
7663 if (loop->entry_edges)
7664 free (loop->entry_edges);
7665 if (loop->exit_edges)
7666 free (loop->exit_edges);
7667 if (loop->exits_doms)
7668 sbitmap_free (loop->exits_doms);
7670 free (loops->array);
7671 loops->array = NULL;
7674 sbitmap_vector_free (loops->cfg.dom);
7675 if (loops->cfg.dfs_order)
7676 free (loops->cfg.dfs_order);
7678 if (loops->shared_headers)
7679 sbitmap_free (loops->shared_headers);
7684 /* Find the entry edges into the loop with header HEADER and nodes
7685 NODES and store in ENTRY_EDGES array. Return the number of entry
7686 edges from the loop. */
7689 flow_loop_entry_edges_find (header, nodes, entry_edges)
7691 const sbitmap nodes;
7697 *entry_edges = NULL;
7700 for (e = header->pred; e; e = e->pred_next)
7702 basic_block src = e->src;
7704 if (src == ENTRY_BLOCK_PTR || ! TEST_BIT (nodes, src->index))
7711 *entry_edges = (edge *) xmalloc (num_entries * sizeof (edge *));
7714 for (e = header->pred; e; e = e->pred_next)
7716 basic_block src = e->src;
7718 if (src == ENTRY_BLOCK_PTR || ! TEST_BIT (nodes, src->index))
7719 (*entry_edges)[num_entries++] = e;
7726 /* Find the exit edges from the loop using the bitmap of loop nodes
7727 NODES and store in EXIT_EDGES array. Return the number of
7728 exit edges from the loop. */
7731 flow_loop_exit_edges_find (nodes, exit_edges)
7732 const sbitmap nodes;
7741 /* Check all nodes within the loop to see if there are any
7742 successors not in the loop. Note that a node may have multiple
7743 exiting edges ????? A node can have one jumping edge and one fallthru
7744 edge so only one of these can exit the loop. */
7746 EXECUTE_IF_SET_IN_SBITMAP (nodes, 0, node, {
7747 for (e = BASIC_BLOCK (node)->succ; e; e = e->succ_next)
7749 basic_block dest = e->dest;
7751 if (dest == EXIT_BLOCK_PTR || ! TEST_BIT (nodes, dest->index))
7759 *exit_edges = (edge *) xmalloc (num_exits * sizeof (edge *));
7761 /* Store all exiting edges into an array. */
7763 EXECUTE_IF_SET_IN_SBITMAP (nodes, 0, node, {
7764 for (e = BASIC_BLOCK (node)->succ; e; e = e->succ_next)
7766 basic_block dest = e->dest;
7768 if (dest == EXIT_BLOCK_PTR || ! TEST_BIT (nodes, dest->index))
7769 (*exit_edges)[num_exits++] = e;
7777 /* Find the nodes contained within the loop with header HEADER and
7778 latch LATCH and store in NODES. Return the number of nodes within
7782 flow_loop_nodes_find (header, latch, nodes)
7791 stack = (basic_block *) xmalloc (n_basic_blocks * sizeof (basic_block));
7794 /* Start with only the loop header in the set of loop nodes. */
7795 sbitmap_zero (nodes);
7796 SET_BIT (nodes, header->index);
7798 header->loop_depth++;
7800 /* Push the loop latch on to the stack. */
7801 if (! TEST_BIT (nodes, latch->index))
7803 SET_BIT (nodes, latch->index);
7804 latch->loop_depth++;
7806 stack[sp++] = latch;
7815 for (e = node->pred; e; e = e->pred_next)
7817 basic_block ancestor = e->src;
7819 /* If each ancestor not marked as part of loop, add to set of
7820 loop nodes and push on to stack. */
7821 if (ancestor != ENTRY_BLOCK_PTR
7822 && ! TEST_BIT (nodes, ancestor->index))
7824 SET_BIT (nodes, ancestor->index);
7825 ancestor->loop_depth++;
7827 stack[sp++] = ancestor;
7835 /* Compute the depth first search order and store in the array
7836 DFS_ORDER if non-zero, marking the nodes visited in VISITED. If
7837 RC_ORDER is non-zero, return the reverse completion number for each
7838 node. Returns the number of nodes visited. A depth first search
7839 tries to get as far away from the starting point as quickly as
7843 flow_depth_first_order_compute (dfs_order, rc_order)
7850 int rcnum = n_basic_blocks - 1;
7853 /* Allocate stack for back-tracking up CFG. */
7854 stack = (edge *) xmalloc ((n_basic_blocks + 1) * sizeof (edge));
7857 /* Allocate bitmap to track nodes that have been visited. */
7858 visited = sbitmap_alloc (n_basic_blocks);
7860 /* None of the nodes in the CFG have been visited yet. */
7861 sbitmap_zero (visited);
7863 /* Push the first edge on to the stack. */
7864 stack[sp++] = ENTRY_BLOCK_PTR->succ;
7872 /* Look at the edge on the top of the stack. */
7877 /* Check if the edge destination has been visited yet. */
7878 if (dest != EXIT_BLOCK_PTR && ! TEST_BIT (visited, dest->index))
7880 /* Mark that we have visited the destination. */
7881 SET_BIT (visited, dest->index);
7884 dfs_order[dfsnum++] = dest->index;
7888 /* Since the DEST node has been visited for the first
7889 time, check its successors. */
7890 stack[sp++] = dest->succ;
7894 /* There are no successors for the DEST node so assign
7895 its reverse completion number. */
7897 rc_order[rcnum--] = dest->index;
7902 if (! e->succ_next && src != ENTRY_BLOCK_PTR)
7904 /* There are no more successors for the SRC node
7905 so assign its reverse completion number. */
7907 rc_order[rcnum--] = src->index;
7911 stack[sp - 1] = e->succ_next;
7918 sbitmap_free (visited);
7920 /* The number of nodes visited should not be greater than
7922 if (dfsnum > n_basic_blocks)
7925 /* There are some nodes left in the CFG that are unreachable. */
7926 if (dfsnum < n_basic_blocks)
7931 /* Compute the depth first search order on the _reverse_ graph and
7932 store in the array DFS_ORDER, marking the nodes visited in VISITED.
7933 Returns the number of nodes visited.
7935 The computation is split into three pieces:
7937 flow_dfs_compute_reverse_init () creates the necessary data
7940 flow_dfs_compute_reverse_add_bb () adds a basic block to the data
7941 structures. The block will start the search.
7943 flow_dfs_compute_reverse_execute () continues (or starts) the
7944 search using the block on the top of the stack, stopping when the
7947 flow_dfs_compute_reverse_finish () destroys the necessary data
7950 Thus, the user will probably call ..._init(), call ..._add_bb() to
7951 add a beginning basic block to the stack, call ..._execute(),
7952 possibly add another bb to the stack and again call ..._execute(),
7953 ..., and finally call _finish(). */
7955 /* Initialize the data structures used for depth-first search on the
7956 reverse graph. If INITIALIZE_STACK is nonzero, the exit block is
7957 added to the basic block stack. DATA is the current depth-first
7958 search context. If INITIALIZE_STACK is non-zero, there is an
7959 element on the stack. */
7962 flow_dfs_compute_reverse_init (data)
7963 depth_first_search_ds data;
7965 /* Allocate stack for back-tracking up CFG. */
7967 (basic_block *) xmalloc ((n_basic_blocks - (INVALID_BLOCK + 1))
7968 * sizeof (basic_block));
7971 /* Allocate bitmap to track nodes that have been visited. */
7972 data->visited_blocks = sbitmap_alloc (n_basic_blocks - (INVALID_BLOCK + 1));
7974 /* None of the nodes in the CFG have been visited yet. */
7975 sbitmap_zero (data->visited_blocks);
7980 /* Add the specified basic block to the top of the dfs data
7981 structures. When the search continues, it will start at the
7985 flow_dfs_compute_reverse_add_bb (data, bb)
7986 depth_first_search_ds data;
7989 data->stack[data->sp++] = bb;
7993 /* Continue the depth-first search through the reverse graph starting
7994 with the block at the stack's top and ending when the stack is
7995 empty. Visited nodes are marked. Returns an unvisited basic
7996 block, or NULL if there is none available. */
7999 flow_dfs_compute_reverse_execute (data)
8000 depth_first_search_ds data;
8006 while (data->sp > 0)
8008 bb = data->stack[--data->sp];
8010 /* Mark that we have visited this node. */
8011 if (!TEST_BIT (data->visited_blocks, bb->index - (INVALID_BLOCK + 1)))
8013 SET_BIT (data->visited_blocks, bb->index - (INVALID_BLOCK + 1));
8015 /* Perform depth-first search on adjacent vertices. */
8016 for (e = bb->pred; e; e = e->pred_next)
8017 flow_dfs_compute_reverse_add_bb (data, e->src);
8021 /* Determine if there are unvisited basic blocks. */
8022 for (i = n_basic_blocks - (INVALID_BLOCK + 1); --i >= 0;)
8023 if (!TEST_BIT (data->visited_blocks, i))
8024 return BASIC_BLOCK (i + (INVALID_BLOCK + 1));
8028 /* Destroy the data structures needed for depth-first search on the
8032 flow_dfs_compute_reverse_finish (data)
8033 depth_first_search_ds data;
8036 sbitmap_free (data->visited_blocks);
8041 /* Find the root node of the loop pre-header extended basic block and
8042 the edges along the trace from the root node to the loop header. */
8045 flow_loop_pre_header_scan (loop)
8051 loop->num_pre_header_edges = 0;
8053 if (loop->num_entries != 1)
8056 ebb = loop->entry_edges[0]->src;
8058 if (ebb != ENTRY_BLOCK_PTR)
8062 /* Count number of edges along trace from loop header to
8063 root of pre-header extended basic block. Usually this is
8064 only one or two edges. */
8066 while (ebb->pred->src != ENTRY_BLOCK_PTR && ! ebb->pred->pred_next)
8068 ebb = ebb->pred->src;
8072 loop->pre_header_edges = (edge *) xmalloc (num * sizeof (edge *));
8073 loop->num_pre_header_edges = num;
8075 /* Store edges in order that they are followed. The source
8076 of the first edge is the root node of the pre-header extended
8077 basic block and the destination of the last last edge is
8079 for (e = loop->entry_edges[0]; num; e = e->src->pred)
8081 loop->pre_header_edges[--num] = e;
8087 /* Return the block for the pre-header of the loop with header
8088 HEADER where DOM specifies the dominator information. Return NULL if
8089 there is no pre-header. */
8092 flow_loop_pre_header_find (header, dom)
8096 basic_block pre_header;
8099 /* If block p is a predecessor of the header and is the only block
8100 that the header does not dominate, then it is the pre-header. */
8102 for (e = header->pred; e; e = e->pred_next)
8104 basic_block node = e->src;
8106 if (node != ENTRY_BLOCK_PTR
8107 && ! TEST_BIT (dom[node->index], header->index))
8109 if (pre_header == NULL)
8113 /* There are multiple edges into the header from outside
8114 the loop so there is no pre-header block. */
8123 /* Add LOOP to the loop hierarchy tree where PREVLOOP was the loop
8124 previously added. The insertion algorithm assumes that the loops
8125 are added in the order found by a depth first search of the CFG. */
8128 flow_loop_tree_node_add (prevloop, loop)
8129 struct loop *prevloop;
8133 if (flow_loop_nested_p (prevloop, loop))
8135 prevloop->inner = loop;
8136 loop->outer = prevloop;
8140 while (prevloop->outer)
8142 if (flow_loop_nested_p (prevloop->outer, loop))
8144 prevloop->next = loop;
8145 loop->outer = prevloop->outer;
8148 prevloop = prevloop->outer;
8151 prevloop->next = loop;
8155 /* Build the loop hierarchy tree for LOOPS. */
8158 flow_loops_tree_build (loops)
8159 struct loops *loops;
8164 num_loops = loops->num;
8168 /* Root the loop hierarchy tree with the first loop found.
8169 Since we used a depth first search this should be the
8171 loops->tree = &loops->array[0];
8172 loops->tree->outer = loops->tree->inner = loops->tree->next = NULL;
8174 /* Add the remaining loops to the tree. */
8175 for (i = 1; i < num_loops; i++)
8176 flow_loop_tree_node_add (&loops->array[i - 1], &loops->array[i]);
8179 /* Helper function to compute loop nesting depth and enclosed loop level
8180 for the natural loop specified by LOOP at the loop depth DEPTH.
8181 Returns the loop level. */
8184 flow_loop_level_compute (loop, depth)
8194 /* Traverse loop tree assigning depth and computing level as the
8195 maximum level of all the inner loops of this loop. The loop
8196 level is equivalent to the height of the loop in the loop tree
8197 and corresponds to the number of enclosed loop levels (including
8199 for (inner = loop->inner; inner; inner = inner->next)
8203 ilevel = flow_loop_level_compute (inner, depth + 1) + 1;
8208 loop->level = level;
8209 loop->depth = depth;
8213 /* Compute the loop nesting depth and enclosed loop level for the loop
8214 hierarchy tree specfied by LOOPS. Return the maximum enclosed loop
8218 flow_loops_level_compute (loops)
8219 struct loops *loops;
8225 /* Traverse all the outer level loops. */
8226 for (loop = loops->tree; loop; loop = loop->next)
8228 level = flow_loop_level_compute (loop, 1);
8236 /* Scan a single natural loop specified by LOOP collecting information
8237 about it specified by FLAGS. */
8240 flow_loop_scan (loops, loop, flags)
8241 struct loops *loops;
8245 /* Determine prerequisites. */
8246 if ((flags & LOOP_EXITS_DOMS) && ! loop->exit_edges)
8247 flags |= LOOP_EXIT_EDGES;
8249 if (flags & LOOP_ENTRY_EDGES)
8251 /* Find edges which enter the loop header.
8252 Note that the entry edges should only
8253 enter the header of a natural loop. */
8255 = flow_loop_entry_edges_find (loop->header,
8257 &loop->entry_edges);
8260 if (flags & LOOP_EXIT_EDGES)
8262 /* Find edges which exit the loop. */
8264 = flow_loop_exit_edges_find (loop->nodes,
8268 if (flags & LOOP_EXITS_DOMS)
8272 /* Determine which loop nodes dominate all the exits
8274 loop->exits_doms = sbitmap_alloc (n_basic_blocks);
8275 sbitmap_copy (loop->exits_doms, loop->nodes);
8276 for (j = 0; j < loop->num_exits; j++)
8277 sbitmap_a_and_b (loop->exits_doms, loop->exits_doms,
8278 loops->cfg.dom[loop->exit_edges[j]->src->index]);
8280 /* The header of a natural loop must dominate
8282 if (! TEST_BIT (loop->exits_doms, loop->header->index))
8286 if (flags & LOOP_PRE_HEADER)
8288 /* Look to see if the loop has a pre-header node. */
8290 = flow_loop_pre_header_find (loop->header, loops->cfg.dom);
8292 /* Find the blocks within the extended basic block of
8293 the loop pre-header. */
8294 flow_loop_pre_header_scan (loop);
8300 /* Find all the natural loops in the function and save in LOOPS structure
8301 and recalculate loop_depth information in basic block structures.
8302 FLAGS controls which loop information is collected.
8303 Return the number of natural loops found. */
8306 flow_loops_find (loops, flags)
8307 struct loops *loops;
8319 /* This function cannot be repeatedly called with different
8320 flags to build up the loop information. The loop tree
8321 must always be built if this function is called. */
8322 if (! (flags & LOOP_TREE))
8325 memset (loops, 0, sizeof (*loops));
8327 /* Taking care of this degenerate case makes the rest of
8328 this code simpler. */
8329 if (n_basic_blocks == 0)
8335 /* Compute the dominators. */
8336 dom = sbitmap_vector_alloc (n_basic_blocks, n_basic_blocks);
8337 calculate_dominance_info (NULL, dom, CDI_DOMINATORS);
8339 /* Count the number of loop edges (back edges). This should be the
8340 same as the number of natural loops. */
8343 for (b = 0; b < n_basic_blocks; b++)
8347 header = BASIC_BLOCK (b);
8348 header->loop_depth = 0;
8350 for (e = header->pred; e; e = e->pred_next)
8352 basic_block latch = e->src;
8354 /* Look for back edges where a predecessor is dominated
8355 by this block. A natural loop has a single entry
8356 node (header) that dominates all the nodes in the
8357 loop. It also has single back edge to the header
8358 from a latch node. Note that multiple natural loops
8359 may share the same header. */
8360 if (b != header->index)
8363 if (latch != ENTRY_BLOCK_PTR && TEST_BIT (dom[latch->index], b))
8370 /* Compute depth first search order of the CFG so that outer
8371 natural loops will be found before inner natural loops. */
8372 dfs_order = (int *) xmalloc (n_basic_blocks * sizeof (int));
8373 rc_order = (int *) xmalloc (n_basic_blocks * sizeof (int));
8374 flow_depth_first_order_compute (dfs_order, rc_order);
8376 /* Save CFG derived information to avoid recomputing it. */
8377 loops->cfg.dom = dom;
8378 loops->cfg.dfs_order = dfs_order;
8379 loops->cfg.rc_order = rc_order;
8381 /* Allocate loop structures. */
8383 = (struct loop *) xcalloc (num_loops, sizeof (struct loop));
8385 headers = sbitmap_alloc (n_basic_blocks);
8386 sbitmap_zero (headers);
8388 loops->shared_headers = sbitmap_alloc (n_basic_blocks);
8389 sbitmap_zero (loops->shared_headers);
8391 /* Find and record information about all the natural loops
8394 for (b = 0; b < n_basic_blocks; b++)
8398 /* Search the nodes of the CFG in reverse completion order
8399 so that we can find outer loops first. */
8400 header = BASIC_BLOCK (rc_order[b]);
8402 /* Look for all the possible latch blocks for this header. */
8403 for (e = header->pred; e; e = e->pred_next)
8405 basic_block latch = e->src;
8407 /* Look for back edges where a predecessor is dominated
8408 by this block. A natural loop has a single entry
8409 node (header) that dominates all the nodes in the
8410 loop. It also has single back edge to the header
8411 from a latch node. Note that multiple natural loops
8412 may share the same header. */
8413 if (latch != ENTRY_BLOCK_PTR
8414 && TEST_BIT (dom[latch->index], header->index))
8418 loop = loops->array + num_loops;
8420 loop->header = header;
8421 loop->latch = latch;
8422 loop->num = num_loops;
8429 for (i = 0; i < num_loops; i++)
8431 struct loop *loop = &loops->array[i];
8433 /* Keep track of blocks that are loop headers so
8434 that we can tell which loops should be merged. */
8435 if (TEST_BIT (headers, loop->header->index))
8436 SET_BIT (loops->shared_headers, loop->header->index);
8437 SET_BIT (headers, loop->header->index);
8439 /* Find nodes contained within the loop. */
8440 loop->nodes = sbitmap_alloc (n_basic_blocks);
8442 = flow_loop_nodes_find (loop->header, loop->latch, loop->nodes);
8444 /* Compute first and last blocks within the loop.
8445 These are often the same as the loop header and
8446 loop latch respectively, but this is not always
8449 = BASIC_BLOCK (sbitmap_first_set_bit (loop->nodes));
8451 = BASIC_BLOCK (sbitmap_last_set_bit (loop->nodes));
8453 flow_loop_scan (loops, loop, flags);
8456 /* Natural loops with shared headers may either be disjoint or
8457 nested. Disjoint loops with shared headers cannot be inner
8458 loops and should be merged. For now just mark loops that share
8460 for (i = 0; i < num_loops; i++)
8461 if (TEST_BIT (loops->shared_headers, loops->array[i].header->index))
8462 loops->array[i].shared = 1;
8464 sbitmap_free (headers);
8467 loops->num = num_loops;
8469 /* Build the loop hierarchy tree. */
8470 flow_loops_tree_build (loops);
8472 /* Assign the loop nesting depth and enclosed loop level for each
8474 loops->levels = flow_loops_level_compute (loops);
8480 /* Update the information regarding the loops in the CFG
8481 specified by LOOPS. */
8483 flow_loops_update (loops, flags)
8484 struct loops *loops;
8487 /* One day we may want to update the current loop data. For now
8488 throw away the old stuff and rebuild what we need. */
8490 flow_loops_free (loops);
8492 return flow_loops_find (loops, flags);
8496 /* Return non-zero if edge E enters header of LOOP from outside of LOOP. */
8499 flow_loop_outside_edge_p (loop, e)
8500 const struct loop *loop;
8503 if (e->dest != loop->header)
8505 return (e->src == ENTRY_BLOCK_PTR)
8506 || ! TEST_BIT (loop->nodes, e->src->index);
8509 /* Clear LOG_LINKS fields of insns in a chain.
8510 Also clear the global_live_at_{start,end} fields of the basic block
8514 clear_log_links (insns)
8520 for (i = insns; i; i = NEXT_INSN (i))
8524 for (b = 0; b < n_basic_blocks; b++)
8526 basic_block bb = BASIC_BLOCK (b);
8528 bb->global_live_at_start = NULL;
8529 bb->global_live_at_end = NULL;
8532 ENTRY_BLOCK_PTR->global_live_at_end = NULL;
8533 EXIT_BLOCK_PTR->global_live_at_start = NULL;
8536 /* Given a register bitmap, turn on the bits in a HARD_REG_SET that
8537 correspond to the hard registers, if any, set in that map. This
8538 could be done far more efficiently by having all sorts of special-cases
8539 with moving single words, but probably isn't worth the trouble. */
8542 reg_set_to_hard_reg_set (to, from)
8548 EXECUTE_IF_SET_IN_BITMAP
8551 if (i >= FIRST_PSEUDO_REGISTER)
8553 SET_HARD_REG_BIT (*to, i);
8557 /* Called once at intialization time. */
8562 static int initialized;
8566 gcc_obstack_init (&flow_obstack);
8567 flow_firstobj = (char *) obstack_alloc (&flow_obstack, 0);
8572 obstack_free (&flow_obstack, flow_firstobj);
8573 flow_firstobj = (char *) obstack_alloc (&flow_obstack, 0);