pr63856 - test case
[official-gcc.git] / gcc / combine-stack-adj.c
blobfa3ec992898eb71261bc06586c01c97c58a67588
1 /* Combine stack adjustments.
2 Copyright (C) 1987-2014 Free Software Foundation, Inc.
4 This file is part of GCC.
6 GCC is free software; you can redistribute it and/or modify it under
7 the terms of the GNU General Public License as published by the Free
8 Software Foundation; either version 3, or (at your option) any later
9 version.
11 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
12 WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 for more details.
16 You should have received a copy of the GNU General Public License
17 along with GCC; see the file COPYING3. If not see
18 <http://www.gnu.org/licenses/>. */
20 /* Track stack adjustments and stack memory references. Attempt to
21 reduce the number of stack adjustments by back-propagating across
22 the memory references.
24 This is intended primarily for use with targets that do not define
25 ACCUMULATE_OUTGOING_ARGS. It is of significantly more value to
26 targets that define PREFERRED_STACK_BOUNDARY more aligned than
27 STACK_BOUNDARY (e.g. x86), or if not all registers can be pushed
28 (e.g. x86 fp regs) which would ordinarily have to be implemented
29 as a sub/mov pair due to restrictions in calls.c.
31 Propagation stops when any of the insns that need adjusting are
32 (a) no longer valid because we've exceeded their range, (b) a
33 non-trivial push instruction, or (c) a call instruction.
35 Restriction B is based on the assumption that push instructions
36 are smaller or faster. If a port really wants to remove all
37 pushes, it should have defined ACCUMULATE_OUTGOING_ARGS. The
38 one exception that is made is for an add immediately followed
39 by a push. */
41 #include "config.h"
42 #include "system.h"
43 #include "coretypes.h"
44 #include "tm.h"
45 #include "rtl.h"
46 #include "tm_p.h"
47 #include "insn-config.h"
48 #include "recog.h"
49 #include "regs.h"
50 #include "hard-reg-set.h"
51 #include "flags.h"
52 #include "hashtab.h"
53 #include "hash-set.h"
54 #include "vec.h"
55 #include "machmode.h"
56 #include "input.h"
57 #include "function.h"
58 #include "expr.h"
59 #include "predict.h"
60 #include "dominance.h"
61 #include "cfg.h"
62 #include "cfgrtl.h"
63 #include "basic-block.h"
64 #include "df.h"
65 #include "except.h"
66 #include "reload.h"
67 #include "tree-pass.h"
68 #include "rtl-iter.h"
71 /* Turn STACK_GROWS_DOWNWARD into a boolean. */
72 #ifdef STACK_GROWS_DOWNWARD
73 #undef STACK_GROWS_DOWNWARD
74 #define STACK_GROWS_DOWNWARD 1
75 #else
76 #define STACK_GROWS_DOWNWARD 0
77 #endif
79 /* This structure records two kinds of stack references between stack
80 adjusting instructions: stack references in memory addresses for
81 regular insns and all stack references for debug insns. */
83 struct csa_reflist
85 HOST_WIDE_INT sp_offset;
86 rtx_insn *insn;
87 rtx *ref;
88 struct csa_reflist *next;
91 static int stack_memref_p (rtx);
92 static rtx single_set_for_csa (rtx_insn *);
93 static void free_csa_reflist (struct csa_reflist *);
94 static struct csa_reflist *record_one_stack_ref (rtx_insn *, rtx *,
95 struct csa_reflist *);
96 static int try_apply_stack_adjustment (rtx_insn *, struct csa_reflist *,
97 HOST_WIDE_INT, HOST_WIDE_INT);
98 static void combine_stack_adjustments_for_block (basic_block);
101 /* Main entry point for stack adjustment combination. */
103 static void
104 combine_stack_adjustments (void)
106 basic_block bb;
108 FOR_EACH_BB_FN (bb, cfun)
109 combine_stack_adjustments_for_block (bb);
112 /* Recognize a MEM of the form (sp) or (plus sp const). */
114 static int
115 stack_memref_p (rtx x)
117 if (!MEM_P (x))
118 return 0;
119 x = XEXP (x, 0);
121 if (x == stack_pointer_rtx)
122 return 1;
123 if (GET_CODE (x) == PLUS
124 && XEXP (x, 0) == stack_pointer_rtx
125 && CONST_INT_P (XEXP (x, 1)))
126 return 1;
128 return 0;
131 /* Recognize either normal single_set or the hack in i386.md for
132 tying fp and sp adjustments. */
134 static rtx
135 single_set_for_csa (rtx_insn *insn)
137 int i;
138 rtx tmp = single_set (insn);
139 if (tmp)
140 return tmp;
142 if (!NONJUMP_INSN_P (insn)
143 || GET_CODE (PATTERN (insn)) != PARALLEL)
144 return NULL_RTX;
146 tmp = PATTERN (insn);
147 if (GET_CODE (XVECEXP (tmp, 0, 0)) != SET)
148 return NULL_RTX;
150 for (i = 1; i < XVECLEN (tmp, 0); ++i)
152 rtx this_rtx = XVECEXP (tmp, 0, i);
154 /* The special case is allowing a no-op set. */
155 if (GET_CODE (this_rtx) == SET
156 && SET_SRC (this_rtx) == SET_DEST (this_rtx))
158 else if (GET_CODE (this_rtx) != CLOBBER
159 && GET_CODE (this_rtx) != USE)
160 return NULL_RTX;
163 return XVECEXP (tmp, 0, 0);
166 /* Free the list of csa_reflist nodes. */
168 static void
169 free_csa_reflist (struct csa_reflist *reflist)
171 struct csa_reflist *next;
172 for (; reflist ; reflist = next)
174 next = reflist->next;
175 free (reflist);
179 /* Create a new csa_reflist node from the given stack reference.
180 It is already known that the reference is either a MEM satisfying the
181 predicate stack_memref_p or a REG representing the stack pointer. */
183 static struct csa_reflist *
184 record_one_stack_ref (rtx_insn *insn, rtx *ref, struct csa_reflist *next_reflist)
186 struct csa_reflist *ml;
188 ml = XNEW (struct csa_reflist);
190 if (REG_P (*ref) || XEXP (*ref, 0) == stack_pointer_rtx)
191 ml->sp_offset = 0;
192 else
193 ml->sp_offset = INTVAL (XEXP (XEXP (*ref, 0), 1));
195 ml->insn = insn;
196 ml->ref = ref;
197 ml->next = next_reflist;
199 return ml;
202 /* We only know how to adjust the CFA; no other frame-related changes
203 may appear in any insn to be deleted. */
205 static bool
206 no_unhandled_cfa (rtx_insn *insn)
208 if (!RTX_FRAME_RELATED_P (insn))
209 return true;
211 /* No CFA notes at all is a legacy interpretation like
212 FRAME_RELATED_EXPR, and is context sensitive within
213 the prologue state machine. We can't handle that here. */
214 bool has_cfa_adjust = false;
216 for (rtx link = REG_NOTES (insn); link; link = XEXP (link, 1))
217 switch (REG_NOTE_KIND (link))
219 default:
220 break;
221 case REG_CFA_ADJUST_CFA:
222 has_cfa_adjust = true;
223 break;
225 case REG_FRAME_RELATED_EXPR:
226 case REG_CFA_DEF_CFA:
227 case REG_CFA_OFFSET:
228 case REG_CFA_REGISTER:
229 case REG_CFA_EXPRESSION:
230 case REG_CFA_RESTORE:
231 case REG_CFA_SET_VDRAP:
232 case REG_CFA_WINDOW_SAVE:
233 case REG_CFA_FLUSH_QUEUE:
234 return false;
237 return has_cfa_adjust;
240 /* Attempt to apply ADJUST to the stack adjusting insn INSN, as well
241 as each of the memories and stack references in REFLIST. Return true
242 on success. */
244 static int
245 try_apply_stack_adjustment (rtx_insn *insn, struct csa_reflist *reflist,
246 HOST_WIDE_INT new_adjust, HOST_WIDE_INT delta)
248 struct csa_reflist *ml;
249 rtx set;
251 set = single_set_for_csa (insn);
252 if (MEM_P (SET_DEST (set)))
253 validate_change (insn, &SET_DEST (set),
254 replace_equiv_address (SET_DEST (set), stack_pointer_rtx),
256 else
257 validate_change (insn, &XEXP (SET_SRC (set), 1), GEN_INT (new_adjust), 1);
259 for (ml = reflist; ml ; ml = ml->next)
261 rtx new_addr = plus_constant (Pmode, stack_pointer_rtx,
262 ml->sp_offset - delta);
263 rtx new_val;
265 if (MEM_P (*ml->ref))
266 new_val = replace_equiv_address_nv (*ml->ref, new_addr);
267 else if (GET_MODE (*ml->ref) == GET_MODE (stack_pointer_rtx))
268 new_val = new_addr;
269 else
270 new_val = lowpart_subreg (GET_MODE (*ml->ref), new_addr,
271 GET_MODE (new_addr));
272 validate_change (ml->insn, ml->ref, new_val, 1);
275 if (apply_change_group ())
277 /* Succeeded. Update our knowledge of the stack references. */
278 for (ml = reflist; ml ; ml = ml->next)
279 ml->sp_offset -= delta;
281 return 1;
283 else
284 return 0;
287 /* For non-debug insns, record all stack memory references in INSN
288 and return true if there were no other (unrecorded) references to the
289 stack pointer. For debug insns, record all stack references regardless
290 of context and unconditionally return true. */
292 static bool
293 record_stack_refs (rtx_insn *insn, struct csa_reflist **reflist)
295 subrtx_ptr_iterator::array_type array;
296 FOR_EACH_SUBRTX_PTR (iter, array, &PATTERN (insn), NONCONST)
298 rtx *loc = *iter;
299 rtx x = *loc;
300 switch (GET_CODE (x))
302 case MEM:
303 if (!reg_mentioned_p (stack_pointer_rtx, x))
304 iter.skip_subrtxes ();
305 /* We are not able to handle correctly all possible memrefs
306 containing stack pointer, so this check is necessary. */
307 else if (stack_memref_p (x))
309 *reflist = record_one_stack_ref (insn, loc, *reflist);
310 iter.skip_subrtxes ();
312 /* Try harder for DEBUG_INSNs, handle e.g.
313 (mem (mem (sp + 16) + 4). */
314 else if (!DEBUG_INSN_P (insn))
315 return false;
316 break;
318 case REG:
319 /* ??? We want be able to handle non-memory stack pointer
320 references later. For now just discard all insns referring to
321 stack pointer outside mem expressions. We would probably
322 want to teach validate_replace to simplify expressions first.
324 We can't just compare with STACK_POINTER_RTX because the
325 reference to the stack pointer might be in some other mode.
326 In particular, an explicit clobber in an asm statement will
327 result in a QImode clobber.
329 In DEBUG_INSNs, we want to replace all occurrences, otherwise
330 they will cause -fcompare-debug failures. */
331 if (REGNO (x) == STACK_POINTER_REGNUM)
333 if (!DEBUG_INSN_P (insn))
334 return false;
335 *reflist = record_one_stack_ref (insn, loc, *reflist);
337 break;
339 default:
340 break;
343 return true;
346 /* If INSN has a REG_ARGS_SIZE note, move it to LAST.
347 AFTER is true iff LAST follows INSN in the instruction stream. */
349 static void
350 maybe_move_args_size_note (rtx_insn *last, rtx_insn *insn, bool after)
352 rtx note, last_note;
354 note = find_reg_note (insn, REG_ARGS_SIZE, NULL_RTX);
355 if (note == NULL)
356 return;
358 last_note = find_reg_note (last, REG_ARGS_SIZE, NULL_RTX);
359 if (last_note)
361 /* The ARGS_SIZE notes are *not* cumulative. They represent an
362 absolute value, and the "most recent" note wins. */
363 if (!after)
364 XEXP (last_note, 0) = XEXP (note, 0);
366 else
367 add_reg_note (last, REG_ARGS_SIZE, XEXP (note, 0));
370 /* Merge any REG_CFA_ADJUST_CFA note from SRC into DST.
371 AFTER is true iff DST follows SRC in the instruction stream. */
373 static void
374 maybe_merge_cfa_adjust (rtx_insn *dst, rtx_insn *src, bool after)
376 rtx snote = NULL, dnote = NULL;
377 rtx sexp, dexp;
378 rtx exp1, exp2;
380 if (RTX_FRAME_RELATED_P (src))
381 snote = find_reg_note (src, REG_CFA_ADJUST_CFA, NULL_RTX);
382 if (snote == NULL)
383 return;
384 sexp = XEXP (snote, 0);
386 if (RTX_FRAME_RELATED_P (dst))
387 dnote = find_reg_note (dst, REG_CFA_ADJUST_CFA, NULL_RTX);
388 if (dnote == NULL)
390 add_reg_note (dst, REG_CFA_ADJUST_CFA, sexp);
391 return;
393 dexp = XEXP (dnote, 0);
395 gcc_assert (GET_CODE (sexp) == SET);
396 gcc_assert (GET_CODE (dexp) == SET);
398 if (after)
399 exp1 = dexp, exp2 = sexp;
400 else
401 exp1 = sexp, exp2 = dexp;
403 SET_SRC (exp1) = simplify_replace_rtx (SET_SRC (exp1), SET_DEST (exp2),
404 SET_SRC (exp2));
405 XEXP (dnote, 0) = exp1;
408 /* Return the next (or previous) active insn within BB. */
410 static rtx_insn *
411 prev_active_insn_bb (basic_block bb, rtx_insn *insn)
413 for (insn = PREV_INSN (insn);
414 insn != PREV_INSN (BB_HEAD (bb));
415 insn = PREV_INSN (insn))
416 if (active_insn_p (insn))
417 return insn;
418 return NULL;
421 static rtx_insn *
422 next_active_insn_bb (basic_block bb, rtx_insn *insn)
424 for (insn = NEXT_INSN (insn);
425 insn != NEXT_INSN (BB_END (bb));
426 insn = NEXT_INSN (insn))
427 if (active_insn_p (insn))
428 return insn;
429 return NULL;
432 /* If INSN has a REG_ARGS_SIZE note, if possible move it to PREV. Otherwise
433 search for a nearby candidate within BB where we can stick the note. */
435 static void
436 force_move_args_size_note (basic_block bb, rtx_insn *prev, rtx_insn *insn)
438 rtx note;
439 rtx_insn *test, *next_candidate, *prev_candidate;
441 /* If PREV exists, tail-call to the logic in the other function. */
442 if (prev)
444 maybe_move_args_size_note (prev, insn, false);
445 return;
448 /* First, make sure there's anything that needs doing. */
449 note = find_reg_note (insn, REG_ARGS_SIZE, NULL_RTX);
450 if (note == NULL)
451 return;
453 /* We need to find a spot between the previous and next exception points
454 where we can place the note and "properly" deallocate the arguments. */
455 next_candidate = prev_candidate = NULL;
457 /* It is often the case that we have insns in the order:
458 call
459 add sp (previous deallocation)
460 sub sp (align for next arglist)
461 push arg
462 and the add/sub cancel. Therefore we begin by searching forward. */
464 test = insn;
465 while ((test = next_active_insn_bb (bb, test)) != NULL)
467 /* Found an existing note: nothing to do. */
468 if (find_reg_note (test, REG_ARGS_SIZE, NULL_RTX))
469 return;
470 /* Found something that affects unwinding. Stop searching. */
471 if (CALL_P (test) || !insn_nothrow_p (test))
472 break;
473 if (next_candidate == NULL)
474 next_candidate = test;
477 test = insn;
478 while ((test = prev_active_insn_bb (bb, test)) != NULL)
480 rtx tnote;
481 /* Found a place that seems logical to adjust the stack. */
482 tnote = find_reg_note (test, REG_ARGS_SIZE, NULL_RTX);
483 if (tnote)
485 XEXP (tnote, 0) = XEXP (note, 0);
486 return;
488 if (prev_candidate == NULL)
489 prev_candidate = test;
490 /* Found something that affects unwinding. Stop searching. */
491 if (CALL_P (test) || !insn_nothrow_p (test))
492 break;
495 if (prev_candidate)
496 test = prev_candidate;
497 else if (next_candidate)
498 test = next_candidate;
499 else
501 /* ??? We *must* have a place, lest we ICE on the lost adjustment.
502 Options are: dummy clobber insn, nop, or prevent the removal of
503 the sp += 0 insn. */
504 /* TODO: Find another way to indicate to the dwarf2 code that we
505 have not in fact lost an adjustment. */
506 test = emit_insn_before (gen_rtx_CLOBBER (VOIDmode, const0_rtx), insn);
508 add_reg_note (test, REG_ARGS_SIZE, XEXP (note, 0));
511 /* Subroutine of combine_stack_adjustments, called for each basic block. */
513 static void
514 combine_stack_adjustments_for_block (basic_block bb)
516 HOST_WIDE_INT last_sp_adjust = 0;
517 rtx_insn *last_sp_set = NULL;
518 rtx_insn *last2_sp_set = NULL;
519 struct csa_reflist *reflist = NULL;
520 rtx_insn *insn, *next;
521 rtx set;
522 bool end_of_block = false;
524 for (insn = BB_HEAD (bb); !end_of_block ; insn = next)
526 end_of_block = insn == BB_END (bb);
527 next = NEXT_INSN (insn);
529 if (! INSN_P (insn))
530 continue;
532 set = single_set_for_csa (insn);
533 if (set)
535 rtx dest = SET_DEST (set);
536 rtx src = SET_SRC (set);
538 /* Find constant additions to the stack pointer. */
539 if (dest == stack_pointer_rtx
540 && GET_CODE (src) == PLUS
541 && XEXP (src, 0) == stack_pointer_rtx
542 && CONST_INT_P (XEXP (src, 1)))
544 HOST_WIDE_INT this_adjust = INTVAL (XEXP (src, 1));
546 /* If we've not seen an adjustment previously, record
547 it now and continue. */
548 if (! last_sp_set)
550 last_sp_set = insn;
551 last_sp_adjust = this_adjust;
552 continue;
555 /* If not all recorded refs can be adjusted, or the
556 adjustment is now too large for a constant addition,
557 we cannot merge the two stack adjustments.
559 Also we need to be careful to not move stack pointer
560 such that we create stack accesses outside the allocated
561 area. We can combine an allocation into the first insn,
562 or a deallocation into the second insn. We can not
563 combine an allocation followed by a deallocation.
565 The only somewhat frequent occurrence of the later is when
566 a function allocates a stack frame but does not use it.
567 For this case, we would need to analyze rtl stream to be
568 sure that allocated area is really unused. This means not
569 only checking the memory references, but also all registers
570 or global memory references possibly containing a stack
571 frame address.
573 Perhaps the best way to address this problem is to teach
574 gcc not to allocate stack for objects never used. */
576 /* Combine an allocation into the first instruction. */
577 if (STACK_GROWS_DOWNWARD ? this_adjust <= 0 : this_adjust >= 0)
579 if (no_unhandled_cfa (insn)
580 && try_apply_stack_adjustment (last_sp_set, reflist,
581 last_sp_adjust
582 + this_adjust,
583 this_adjust))
585 /* It worked! */
586 maybe_move_args_size_note (last_sp_set, insn, false);
587 maybe_merge_cfa_adjust (last_sp_set, insn, false);
588 delete_insn (insn);
589 last_sp_adjust += this_adjust;
590 continue;
594 /* Otherwise we have a deallocation. Do not combine with
595 a previous allocation. Combine into the second insn. */
596 else if (STACK_GROWS_DOWNWARD
597 ? last_sp_adjust >= 0 : last_sp_adjust <= 0)
599 if (no_unhandled_cfa (last_sp_set)
600 && try_apply_stack_adjustment (insn, reflist,
601 last_sp_adjust
602 + this_adjust,
603 -last_sp_adjust))
605 /* It worked! */
606 maybe_move_args_size_note (insn, last_sp_set, true);
607 maybe_merge_cfa_adjust (insn, last_sp_set, true);
608 delete_insn (last_sp_set);
609 last_sp_set = insn;
610 last_sp_adjust += this_adjust;
611 free_csa_reflist (reflist);
612 reflist = NULL;
613 continue;
617 /* Combination failed. Restart processing from here. If
618 deallocation+allocation conspired to cancel, we can
619 delete the old deallocation insn. */
620 if (last_sp_set)
622 if (last_sp_adjust == 0 && no_unhandled_cfa (last_sp_set))
624 maybe_move_args_size_note (insn, last_sp_set, true);
625 maybe_merge_cfa_adjust (insn, last_sp_set, true);
626 delete_insn (last_sp_set);
628 else
629 last2_sp_set = last_sp_set;
631 free_csa_reflist (reflist);
632 reflist = NULL;
633 last_sp_set = insn;
634 last_sp_adjust = this_adjust;
635 continue;
638 /* Find a store with pre-(dec|inc)rement or pre-modify of exactly
639 the previous adjustment and turn it into a simple store. This
640 is equivalent to anticipating the stack adjustment so this must
641 be an allocation. */
642 if (MEM_P (dest)
643 && ((STACK_GROWS_DOWNWARD
644 ? (GET_CODE (XEXP (dest, 0)) == PRE_DEC
645 && last_sp_adjust
646 == (HOST_WIDE_INT) GET_MODE_SIZE (GET_MODE (dest)))
647 : (GET_CODE (XEXP (dest, 0)) == PRE_INC
648 && last_sp_adjust
649 == -(HOST_WIDE_INT) GET_MODE_SIZE (GET_MODE (dest))))
650 || ((STACK_GROWS_DOWNWARD
651 ? last_sp_adjust >= 0 : last_sp_adjust <= 0)
652 && GET_CODE (XEXP (dest, 0)) == PRE_MODIFY
653 && GET_CODE (XEXP (XEXP (dest, 0), 1)) == PLUS
654 && XEXP (XEXP (XEXP (dest, 0), 1), 0)
655 == stack_pointer_rtx
656 && GET_CODE (XEXP (XEXP (XEXP (dest, 0), 1), 1))
657 == CONST_INT
658 && INTVAL (XEXP (XEXP (XEXP (dest, 0), 1), 1))
659 == -last_sp_adjust))
660 && XEXP (XEXP (dest, 0), 0) == stack_pointer_rtx
661 && !reg_mentioned_p (stack_pointer_rtx, src)
662 && memory_address_p (GET_MODE (dest), stack_pointer_rtx)
663 && try_apply_stack_adjustment (insn, reflist, 0,
664 -last_sp_adjust))
666 if (last2_sp_set)
667 maybe_move_args_size_note (last2_sp_set, last_sp_set, false);
668 else
669 maybe_move_args_size_note (insn, last_sp_set, true);
670 delete_insn (last_sp_set);
671 free_csa_reflist (reflist);
672 reflist = NULL;
673 last_sp_set = NULL;
674 last_sp_adjust = 0;
675 continue;
679 if (!CALL_P (insn) && last_sp_set
680 && record_stack_refs (insn, &reflist))
681 continue;
683 /* Otherwise, we were not able to process the instruction.
684 Do not continue collecting data across such a one. */
685 if (last_sp_set
686 && (CALL_P (insn)
687 || reg_mentioned_p (stack_pointer_rtx, PATTERN (insn))))
689 if (last_sp_set && last_sp_adjust == 0)
691 force_move_args_size_note (bb, last2_sp_set, last_sp_set);
692 delete_insn (last_sp_set);
694 free_csa_reflist (reflist);
695 reflist = NULL;
696 last2_sp_set = NULL;
697 last_sp_set = NULL;
698 last_sp_adjust = 0;
702 if (last_sp_set && last_sp_adjust == 0)
704 force_move_args_size_note (bb, last2_sp_set, last_sp_set);
705 delete_insn (last_sp_set);
708 if (reflist)
709 free_csa_reflist (reflist);
712 static unsigned int
713 rest_of_handle_stack_adjustments (void)
715 df_note_add_problem ();
716 df_analyze ();
717 combine_stack_adjustments ();
718 return 0;
721 namespace {
723 const pass_data pass_data_stack_adjustments =
725 RTL_PASS, /* type */
726 "csa", /* name */
727 OPTGROUP_NONE, /* optinfo_flags */
728 TV_COMBINE_STACK_ADJUST, /* tv_id */
729 0, /* properties_required */
730 0, /* properties_provided */
731 0, /* properties_destroyed */
732 0, /* todo_flags_start */
733 TODO_df_finish, /* todo_flags_finish */
736 class pass_stack_adjustments : public rtl_opt_pass
738 public:
739 pass_stack_adjustments (gcc::context *ctxt)
740 : rtl_opt_pass (pass_data_stack_adjustments, ctxt)
743 /* opt_pass methods: */
744 virtual bool gate (function *);
745 virtual unsigned int execute (function *)
747 return rest_of_handle_stack_adjustments ();
750 }; // class pass_stack_adjustments
752 bool
753 pass_stack_adjustments::gate (function *)
755 /* This is kind of a heuristic. We need to run combine_stack_adjustments
756 even for machines with possibly nonzero TARGET_RETURN_POPS_ARGS
757 and ACCUMULATE_OUTGOING_ARGS. We expect that only ports having
758 push instructions will have popping returns. */
759 #ifndef PUSH_ROUNDING
760 if (ACCUMULATE_OUTGOING_ARGS)
761 return false;
762 #endif
763 return flag_combine_stack_adjustments;
766 } // anon namespace
768 rtl_opt_pass *
769 make_pass_stack_adjustments (gcc::context *ctxt)
771 return new pass_stack_adjustments (ctxt);