1 /* Shrink-wrapping related optimizations.
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
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
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 /* This file handles shrink-wrapping related optimizations. */
24 #include "coretypes.h"
26 #include "rtl-error.h"
28 #include "stor-layout.h"
30 #include "stringpool.h"
38 #include "hard-reg-set.h"
39 #include "insn-config.h"
44 #include "langhooks.h"
46 #include "common/common-target.h"
47 #include "gimple-expr.h"
49 #include "tree-pass.h"
53 #include "bb-reorder.h"
54 #include "shrink-wrap.h"
57 #ifdef HAVE_simple_return
59 /* Return true if INSN requires the stack frame to be set up.
60 PROLOGUE_USED contains the hard registers used in the function
61 prologue. SET_UP_BY_PROLOGUE is the set of registers we expect the
62 prologue to set up for the function. */
64 requires_stack_frame_p (rtx insn, HARD_REG_SET prologue_used,
65 HARD_REG_SET set_up_by_prologue)
68 HARD_REG_SET hardregs;
72 return !SIBLING_CALL_P (insn);
74 /* We need a frame to get the unique CFA expected by the unwinder. */
75 if (cfun->can_throw_non_call_exceptions && can_throw_internal (insn))
78 CLEAR_HARD_REG_SET (hardregs);
79 for (df_rec = DF_INSN_DEFS (insn); *df_rec; df_rec++)
81 rtx dreg = DF_REF_REG (*df_rec);
86 add_to_hard_reg_set (&hardregs, GET_MODE (dreg),
89 if (hard_reg_set_intersect_p (hardregs, prologue_used))
91 AND_COMPL_HARD_REG_SET (hardregs, call_used_reg_set);
92 for (regno = 0; regno < FIRST_PSEUDO_REGISTER; regno++)
93 if (TEST_HARD_REG_BIT (hardregs, regno)
94 && df_regs_ever_live_p (regno))
97 for (df_rec = DF_INSN_USES (insn); *df_rec; df_rec++)
99 rtx reg = DF_REF_REG (*df_rec);
104 add_to_hard_reg_set (&hardregs, GET_MODE (reg),
107 if (hard_reg_set_intersect_p (hardregs, set_up_by_prologue))
113 /* See whether there has a single live edge from BB, which dest uses
114 [REGNO, END_REGNO). Return the live edge if its dest bb has
115 one or two predecessors. Otherwise return NULL. */
118 live_edge_for_reg (basic_block bb, int regno, int end_regno)
126 FOR_EACH_EDGE (e, ei, bb->succs)
128 live = df_get_live_in (e->dest);
129 for (i = regno; i < end_regno; i++)
130 if (REGNO_REG_SET_P (live, i))
132 if (live_edge && live_edge != e)
138 /* We can sometimes encounter dead code. Don't try to move it
139 into the exit block. */
140 if (!live_edge || live_edge->dest == EXIT_BLOCK_PTR_FOR_FN (cfun))
143 /* Reject targets of abnormal edges. This is needed for correctness
144 on ports like Alpha and MIPS, whose pic_offset_table_rtx can die on
145 exception edges even though it is generally treated as call-saved
146 for the majority of the compilation. Moving across abnormal edges
147 isn't going to be interesting for shrink-wrap usage anyway. */
148 if (live_edge->flags & EDGE_ABNORMAL)
151 /* When live_edge->dest->preds == 2, we can create a new block on
152 the edge to make it meet the requirement. */
153 if (EDGE_COUNT (live_edge->dest->preds) > 2)
159 /* Try to move INSN from BB to a successor. Return true on success.
160 USES and DEFS are the set of registers that are used and defined
161 after INSN in BB. SPLIT_P indicates whether a live edge from BB
162 is splitted or not. */
165 move_insn_for_shrink_wrap (basic_block bb, rtx insn,
166 const HARD_REG_SET uses,
167 const HARD_REG_SET defs,
171 bitmap live_out, live_in, bb_uses, bb_defs;
172 unsigned int i, dregno, end_dregno, sregno, end_sregno;
173 basic_block next_block;
176 /* Look for a simple register copy. */
177 set = single_set (insn);
181 dest = SET_DEST (set);
182 if (!REG_P (dest) || !REG_P (src))
185 /* Make sure that the source register isn't defined later in BB. */
186 sregno = REGNO (src);
187 end_sregno = END_REGNO (src);
188 if (overlaps_hard_reg_set_p (defs, GET_MODE (src), sregno))
191 /* Make sure that the destination register isn't referenced later in BB. */
192 dregno = REGNO (dest);
193 end_dregno = END_REGNO (dest);
194 if (overlaps_hard_reg_set_p (uses, GET_MODE (dest), dregno)
195 || overlaps_hard_reg_set_p (defs, GET_MODE (dest), dregno))
198 /* See whether there is a successor block to which we could move INSN. */
199 live_edge = live_edge_for_reg (bb, dregno, end_dregno);
203 next_block = live_edge->dest;
204 /* Create a new basic block on the edge. */
205 if (EDGE_COUNT (next_block->preds) == 2)
207 next_block = split_edge (live_edge);
209 bitmap_copy (df_get_live_in (next_block), df_get_live_out (bb));
210 df_set_bb_dirty (next_block);
212 /* We should not split more than once for a function. */
213 gcc_assert (!(*split_p));
217 /* At this point we are committed to moving INSN, but let's try to
218 move it as far as we can. */
221 live_out = df_get_live_out (bb);
222 live_in = df_get_live_in (next_block);
225 /* Check whether BB uses DEST or clobbers DEST. We need to add
226 INSN to BB if so. Either way, DEST is no longer live on entry,
227 except for any part that overlaps SRC (next loop). */
228 bb_uses = &DF_LR_BB_INFO (bb)->use;
229 bb_defs = &DF_LR_BB_INFO (bb)->def;
232 for (i = dregno; i < end_dregno; i++)
235 || REGNO_REG_SET_P (bb_uses, i)
236 || REGNO_REG_SET_P (bb_defs, i)
237 || REGNO_REG_SET_P (&DF_LIVE_BB_INFO (bb)->gen, i))
239 CLEAR_REGNO_REG_SET (live_out, i);
240 CLEAR_REGNO_REG_SET (live_in, i);
243 /* Check whether BB clobbers SRC. We need to add INSN to BB if so.
244 Either way, SRC is now live on entry. */
245 for (i = sregno; i < end_sregno; i++)
248 || REGNO_REG_SET_P (bb_defs, i)
249 || REGNO_REG_SET_P (&DF_LIVE_BB_INFO (bb)->gen, i))
251 SET_REGNO_REG_SET (live_out, i);
252 SET_REGNO_REG_SET (live_in, i);
257 /* DF_LR_BB_INFO (bb)->def does not comprise the DF_REF_PARTIAL and
258 DF_REF_CONDITIONAL defs. So if DF_LIVE doesn't exist, i.e.
259 at -O1, just give up searching NEXT_BLOCK. */
261 for (i = dregno; i < end_dregno; i++)
263 CLEAR_REGNO_REG_SET (live_out, i);
264 CLEAR_REGNO_REG_SET (live_in, i);
267 for (i = sregno; i < end_sregno; i++)
269 SET_REGNO_REG_SET (live_out, i);
270 SET_REGNO_REG_SET (live_in, i);
274 /* If we don't need to add the move to BB, look for a single
278 live_edge = live_edge_for_reg (next_block, dregno, end_dregno);
279 if (!live_edge || EDGE_COUNT (live_edge->dest->preds) > 1)
281 next_block = live_edge->dest;
286 /* For the new created basic block, there is no dataflow info at all.
287 So skip the following dataflow update and check. */
290 /* BB now defines DEST. It only uses the parts of DEST that overlap SRC
292 for (i = dregno; i < end_dregno; i++)
294 CLEAR_REGNO_REG_SET (bb_uses, i);
295 SET_REGNO_REG_SET (bb_defs, i);
298 /* BB now uses SRC. */
299 for (i = sregno; i < end_sregno; i++)
300 SET_REGNO_REG_SET (bb_uses, i);
303 emit_insn_after (PATTERN (insn), bb_note (bb));
308 /* Look for register copies in the first block of the function, and move
309 them down into successor blocks if the register is used only on one
310 path. This exposes more opportunities for shrink-wrapping. These
311 kinds of sets often occur when incoming argument registers are moved
312 to call-saved registers because their values are live across one or
313 more calls during the function. */
316 prepare_shrink_wrap (basic_block entry_block)
319 HARD_REG_SET uses, defs;
321 bool split_p = false;
323 if (JUMP_P (BB_END (entry_block)))
325 /* To have more shrink-wrapping opportunities, prepare_shrink_wrap tries
326 to sink the copies from parameter to callee saved register out of
327 entry block. copyprop_hardreg_forward_bb_without_debug_insn is called
328 to release some dependences. */
329 copyprop_hardreg_forward_bb_without_debug_insn (entry_block);
332 CLEAR_HARD_REG_SET (uses);
333 CLEAR_HARD_REG_SET (defs);
334 FOR_BB_INSNS_REVERSE_SAFE (entry_block, insn, curr)
335 if (NONDEBUG_INSN_P (insn)
336 && !move_insn_for_shrink_wrap (entry_block, insn, uses, defs,
339 /* Add all defined registers to DEFs. */
340 for (ref = DF_INSN_DEFS (insn); *ref; ref++)
342 x = DF_REF_REG (*ref);
343 if (REG_P (x) && HARD_REGISTER_P (x))
344 SET_HARD_REG_BIT (defs, REGNO (x));
347 /* Add all used registers to USESs. */
348 for (ref = DF_INSN_USES (insn); *ref; ref++)
350 x = DF_REF_REG (*ref);
351 if (REG_P (x) && HARD_REGISTER_P (x))
352 SET_HARD_REG_BIT (uses, REGNO (x));
357 /* Create a copy of BB instructions and insert at BEFORE. Redirect
358 preds of BB to COPY_BB if they don't appear in NEED_PROLOGUE. */
360 dup_block_and_redirect (basic_block bb, basic_block copy_bb, rtx before,
361 bitmap_head *need_prologue)
365 rtx insn = BB_END (bb);
367 /* We know BB has a single successor, so there is no need to copy a
368 simple jump at the end of BB. */
369 if (simplejump_p (insn))
370 insn = PREV_INSN (insn);
373 duplicate_insn_chain (BB_HEAD (bb), insn);
377 for (insn = get_insns (); insn; insn = NEXT_INSN (insn))
378 if (active_insn_p (insn))
380 fprintf (dump_file, "Duplicating bb %d to bb %d, %u active insns.\n",
381 bb->index, copy_bb->index, count);
385 emit_insn_before (insn, before);
387 /* Redirect all the paths that need no prologue into copy_bb. */
388 for (ei = ei_start (bb->preds); (e = ei_safe_edge (ei));)
389 if (!bitmap_bit_p (need_prologue, e->src->index))
391 int freq = EDGE_FREQUENCY (e);
392 copy_bb->count += e->count;
393 copy_bb->frequency += EDGE_FREQUENCY (e);
394 e->dest->count -= e->count;
395 if (e->dest->count < 0)
397 e->dest->frequency -= freq;
398 if (e->dest->frequency < 0)
399 e->dest->frequency = 0;
400 redirect_edge_and_branch_force (e, copy_bb);
408 /* Try to perform a kind of shrink-wrapping, making sure the
409 prologue/epilogue is emitted only around those parts of the
410 function that require it. */
413 try_shrink_wrapping (edge *entry_edge, edge orig_entry_edge,
414 bitmap_head *bb_flags, rtx prologue_seq)
418 bool nonempty_prologue = false;
419 unsigned max_grow_size;
422 for (seq = prologue_seq; seq; seq = NEXT_INSN (seq))
423 if (!NOTE_P (seq) || NOTE_KIND (seq) != NOTE_INSN_PROLOGUE_END)
425 nonempty_prologue = true;
429 if (flag_shrink_wrap && HAVE_simple_return
430 && (targetm.profile_before_prologue () || !crtl->profile)
431 && nonempty_prologue && !crtl->calls_eh_return)
433 HARD_REG_SET prologue_clobbered, prologue_used, live_on_edge;
434 struct hard_reg_set_container set_up_by_prologue;
436 vec<basic_block> vec;
438 bitmap_head bb_antic_flags;
439 bitmap_head bb_on_list;
443 fprintf (dump_file, "Attempting shrink-wrapping optimization.\n");
445 /* Compute the registers set and used in the prologue. */
446 CLEAR_HARD_REG_SET (prologue_clobbered);
447 CLEAR_HARD_REG_SET (prologue_used);
448 for (p_insn = prologue_seq; p_insn; p_insn = NEXT_INSN (p_insn))
450 HARD_REG_SET this_used;
451 if (!NONDEBUG_INSN_P (p_insn))
454 CLEAR_HARD_REG_SET (this_used);
455 note_uses (&PATTERN (p_insn), record_hard_reg_uses,
457 AND_COMPL_HARD_REG_SET (this_used, prologue_clobbered);
458 IOR_HARD_REG_SET (prologue_used, this_used);
459 note_stores (PATTERN (p_insn), record_hard_reg_sets,
460 &prologue_clobbered);
463 prepare_shrink_wrap ((*entry_edge)->dest);
465 bitmap_initialize (&bb_antic_flags, &bitmap_default_obstack);
466 bitmap_initialize (&bb_on_list, &bitmap_default_obstack);
467 bitmap_initialize (&bb_tail, &bitmap_default_obstack);
469 /* Find the set of basic blocks that require a stack frame,
470 and blocks that are too big to be duplicated. */
472 vec.create (n_basic_blocks_for_fn (cfun));
474 CLEAR_HARD_REG_SET (set_up_by_prologue.set);
475 add_to_hard_reg_set (&set_up_by_prologue.set, Pmode,
476 STACK_POINTER_REGNUM);
477 add_to_hard_reg_set (&set_up_by_prologue.set, Pmode, ARG_POINTER_REGNUM);
478 if (frame_pointer_needed)
479 add_to_hard_reg_set (&set_up_by_prologue.set, Pmode,
480 HARD_FRAME_POINTER_REGNUM);
481 if (pic_offset_table_rtx)
482 add_to_hard_reg_set (&set_up_by_prologue.set, Pmode,
483 PIC_OFFSET_TABLE_REGNUM);
485 add_to_hard_reg_set (&set_up_by_prologue.set,
486 GET_MODE (crtl->drap_reg),
487 REGNO (crtl->drap_reg));
488 if (targetm.set_up_by_prologue)
489 targetm.set_up_by_prologue (&set_up_by_prologue);
491 /* We don't use a different max size depending on
492 optimize_bb_for_speed_p because increasing shrink-wrapping
493 opportunities by duplicating tail blocks can actually result
494 in an overall decrease in code size. */
495 max_grow_size = get_uncond_jump_length ();
496 max_grow_size *= PARAM_VALUE (PARAM_MAX_GROW_COPY_BB_INSNS);
498 FOR_EACH_BB_FN (bb, cfun)
503 FOR_BB_INSNS (bb, insn)
504 if (NONDEBUG_INSN_P (insn))
506 if (requires_stack_frame_p (insn, prologue_used,
507 set_up_by_prologue.set))
509 if (bb == (*entry_edge)->dest)
510 goto fail_shrinkwrap;
511 bitmap_set_bit (bb_flags, bb->index);
515 else if (size <= max_grow_size)
517 size += get_attr_min_length (insn);
518 if (size > max_grow_size)
519 bitmap_set_bit (&bb_on_list, bb->index);
524 /* Blocks that really need a prologue, or are too big for tails. */
525 bitmap_ior_into (&bb_on_list, bb_flags);
527 /* For every basic block that needs a prologue, mark all blocks
528 reachable from it, so as to ensure they are also seen as
529 requiring a prologue. */
530 while (!vec.is_empty ())
532 basic_block tmp_bb = vec.pop ();
534 FOR_EACH_EDGE (e, ei, tmp_bb->succs)
535 if (e->dest != EXIT_BLOCK_PTR_FOR_FN (cfun)
536 && bitmap_set_bit (bb_flags, e->dest->index))
537 vec.quick_push (e->dest);
540 /* Find the set of basic blocks that need no prologue, have a
541 single successor, can be duplicated, meet a max size
542 requirement, and go to the exit via like blocks. */
543 vec.quick_push (EXIT_BLOCK_PTR_FOR_FN (cfun));
544 while (!vec.is_empty ())
546 basic_block tmp_bb = vec.pop ();
548 FOR_EACH_EDGE (e, ei, tmp_bb->preds)
549 if (single_succ_p (e->src)
550 && !bitmap_bit_p (&bb_on_list, e->src->index)
551 && can_duplicate_block_p (e->src))
556 /* If there is predecessor of e->src which doesn't
557 need prologue and the edge is complex,
558 we might not be able to redirect the branch
559 to a copy of e->src. */
560 FOR_EACH_EDGE (pe, pei, e->src->preds)
561 if ((pe->flags & EDGE_COMPLEX) != 0
562 && !bitmap_bit_p (bb_flags, pe->src->index))
564 if (pe == NULL && bitmap_set_bit (&bb_tail, e->src->index))
565 vec.quick_push (e->src);
569 /* Now walk backwards from every block that is marked as needing
570 a prologue to compute the bb_antic_flags bitmap. Exclude
571 tail blocks; They can be duplicated to be used on paths not
572 needing a prologue. */
573 bitmap_clear (&bb_on_list);
574 bitmap_and_compl (&bb_antic_flags, bb_flags, &bb_tail);
575 FOR_EACH_BB_FN (bb, cfun)
577 if (!bitmap_bit_p (&bb_antic_flags, bb->index))
579 FOR_EACH_EDGE (e, ei, bb->preds)
580 if (!bitmap_bit_p (&bb_antic_flags, e->src->index)
581 && bitmap_set_bit (&bb_on_list, e->src->index))
582 vec.quick_push (e->src);
584 while (!vec.is_empty ())
586 basic_block tmp_bb = vec.pop ();
589 bitmap_clear_bit (&bb_on_list, tmp_bb->index);
590 FOR_EACH_EDGE (e, ei, tmp_bb->succs)
591 if (!bitmap_bit_p (&bb_antic_flags, e->dest->index))
599 bitmap_set_bit (&bb_antic_flags, tmp_bb->index);
600 FOR_EACH_EDGE (e, ei, tmp_bb->preds)
601 if (!bitmap_bit_p (&bb_antic_flags, e->src->index)
602 && bitmap_set_bit (&bb_on_list, e->src->index))
603 vec.quick_push (e->src);
606 /* Find exactly one edge that leads to a block in ANTIC from
607 a block that isn't. */
608 if (!bitmap_bit_p (&bb_antic_flags, (*entry_edge)->dest->index))
609 FOR_EACH_BB_FN (bb, cfun)
611 if (!bitmap_bit_p (&bb_antic_flags, bb->index))
613 FOR_EACH_EDGE (e, ei, bb->preds)
614 if (!bitmap_bit_p (&bb_antic_flags, e->src->index))
616 if (*entry_edge != orig_entry_edge)
618 *entry_edge = orig_entry_edge;
620 fprintf (dump_file, "More than one candidate edge.\n");
621 goto fail_shrinkwrap;
624 fprintf (dump_file, "Found candidate edge for "
625 "shrink-wrapping, %d->%d.\n", e->src->index,
631 if (*entry_edge != orig_entry_edge)
633 /* Test whether the prologue is known to clobber any register
634 (other than FP or SP) which are live on the edge. */
635 CLEAR_HARD_REG_BIT (prologue_clobbered, STACK_POINTER_REGNUM);
636 if (frame_pointer_needed)
637 CLEAR_HARD_REG_BIT (prologue_clobbered, HARD_FRAME_POINTER_REGNUM);
638 REG_SET_TO_HARD_REG_SET (live_on_edge,
639 df_get_live_in ((*entry_edge)->dest));
640 if (hard_reg_set_intersect_p (live_on_edge, prologue_clobbered))
642 *entry_edge = orig_entry_edge;
645 "Shrink-wrapping aborted due to clobber.\n");
648 if (*entry_edge != orig_entry_edge)
650 crtl->shrink_wrapped = true;
652 fprintf (dump_file, "Performing shrink-wrapping.\n");
654 /* Find tail blocks reachable from both blocks needing a
655 prologue and blocks not needing a prologue. */
656 if (!bitmap_empty_p (&bb_tail))
657 FOR_EACH_BB_FN (bb, cfun)
659 bool some_pro, some_no_pro;
660 if (!bitmap_bit_p (&bb_tail, bb->index))
662 some_pro = some_no_pro = false;
663 FOR_EACH_EDGE (e, ei, bb->preds)
665 if (bitmap_bit_p (bb_flags, e->src->index))
670 if (some_pro && some_no_pro)
673 bitmap_clear_bit (&bb_tail, bb->index);
675 /* Find the head of each tail. */
676 while (!vec.is_empty ())
678 basic_block tbb = vec.pop ();
680 if (!bitmap_bit_p (&bb_tail, tbb->index))
683 while (single_succ_p (tbb))
685 tbb = single_succ (tbb);
686 bitmap_clear_bit (&bb_tail, tbb->index);
689 /* Now duplicate the tails. */
690 if (!bitmap_empty_p (&bb_tail))
691 FOR_EACH_BB_REVERSE_FN (bb, cfun)
693 basic_block copy_bb, tbb;
697 if (!bitmap_clear_bit (&bb_tail, bb->index))
700 /* Create a copy of BB, instructions and all, for
701 use on paths that don't need a prologue.
702 Ideal placement of the copy is on a fall-thru edge
703 or after a block that would jump to the copy. */
704 FOR_EACH_EDGE (e, ei, bb->preds)
705 if (!bitmap_bit_p (bb_flags, e->src->index)
706 && single_succ_p (e->src))
710 /* Make sure we insert after any barriers. */
711 rtx end = get_last_bb_insn (e->src);
712 copy_bb = create_basic_block (NEXT_INSN (end),
714 BB_COPY_PARTITION (copy_bb, e->src);
718 /* Otherwise put the copy at the end of the function. */
719 copy_bb = create_basic_block (NULL_RTX, NULL_RTX,
720 EXIT_BLOCK_PTR_FOR_FN (cfun)->prev_bb);
721 BB_COPY_PARTITION (copy_bb, bb);
724 insert_point = emit_note_after (NOTE_INSN_DELETED,
726 emit_barrier_after (BB_END (copy_bb));
731 dup_block_and_redirect (tbb, copy_bb, insert_point,
733 tbb = single_succ (tbb);
734 if (tbb == EXIT_BLOCK_PTR_FOR_FN (cfun))
736 e = split_block (copy_bb, PREV_INSN (insert_point));
740 /* Quiet verify_flow_info by (ab)using EDGE_FAKE.
741 We have yet to add a simple_return to the tails,
742 as we'd like to first convert_jumps_to_returns in
743 case the block is no longer used after that. */
745 if (CALL_P (PREV_INSN (insert_point))
746 && SIBLING_CALL_P (PREV_INSN (insert_point)))
747 eflags = EDGE_SIBCALL | EDGE_ABNORMAL;
748 make_single_succ_edge (copy_bb, EXIT_BLOCK_PTR_FOR_FN (cfun),
751 /* verify_flow_info doesn't like a note after a
753 delete_insn (insert_point);
754 if (bitmap_empty_p (&bb_tail))
760 bitmap_clear (&bb_tail);
761 bitmap_clear (&bb_antic_flags);
762 bitmap_clear (&bb_on_list);
767 /* If we're allowed to generate a simple return instruction, then by
768 definition we don't need a full epilogue. If the last basic
769 block before the exit block does not contain active instructions,
770 examine its predecessors and try to emit (conditional) return
774 get_unconverted_simple_return (edge exit_fallthru_edge, bitmap_head bb_flags,
775 vec<edge> *unconverted_simple_returns,
782 /* convert_jumps_to_returns may add to preds of the exit block
783 (but won't remove). Stop at end of current preds. */
784 last = EDGE_COUNT (EXIT_BLOCK_PTR_FOR_FN (cfun)->preds);
785 for (i = 0; i < last; i++)
787 edge e = EDGE_I (EXIT_BLOCK_PTR_FOR_FN (cfun)->preds, i);
788 if (LABEL_P (BB_HEAD (e->src))
789 && !bitmap_bit_p (&bb_flags, e->src->index)
790 && !active_insn_between (BB_HEAD (e->src), BB_END (e->src)))
791 *unconverted_simple_returns
792 = convert_jumps_to_returns (e->src, true,
793 *unconverted_simple_returns);
797 if (exit_fallthru_edge != NULL
798 && EDGE_COUNT (exit_fallthru_edge->src->preds) != 0
799 && !bitmap_bit_p (&bb_flags, exit_fallthru_edge->src->index))
803 last_bb = emit_return_for_exit (exit_fallthru_edge, true);
804 *returnjump = BB_END (last_bb);
805 exit_fallthru_edge = NULL;
807 return exit_fallthru_edge;
810 /* If there were branches to an empty LAST_BB which we tried to
811 convert to conditional simple_returns, but couldn't for some
812 reason, create a block to hold a simple_return insn and redirect
813 those remaining edges. */
816 convert_to_simple_return (edge entry_edge, edge orig_entry_edge,
817 bitmap_head bb_flags, rtx returnjump,
818 vec<edge> unconverted_simple_returns)
823 if (!unconverted_simple_returns.is_empty ())
825 basic_block simple_return_block_hot = NULL;
826 basic_block simple_return_block_cold = NULL;
827 edge pending_edge_hot = NULL;
828 edge pending_edge_cold = NULL;
829 basic_block exit_pred;
832 gcc_assert (entry_edge != orig_entry_edge);
834 /* See if we can reuse the last insn that was emitted for the
836 if (returnjump != NULL_RTX
837 && JUMP_LABEL (returnjump) == simple_return_rtx)
839 e = split_block (BLOCK_FOR_INSN (returnjump), PREV_INSN (returnjump));
840 if (BB_PARTITION (e->src) == BB_HOT_PARTITION)
841 simple_return_block_hot = e->dest;
843 simple_return_block_cold = e->dest;
846 /* Also check returns we might need to add to tail blocks. */
847 FOR_EACH_EDGE (e, ei, EXIT_BLOCK_PTR_FOR_FN (cfun)->preds)
848 if (EDGE_COUNT (e->src->preds) != 0
849 && (e->flags & EDGE_FAKE) != 0
850 && !bitmap_bit_p (&bb_flags, e->src->index))
852 if (BB_PARTITION (e->src) == BB_HOT_PARTITION)
853 pending_edge_hot = e;
855 pending_edge_cold = e;
858 /* Save a pointer to the exit's predecessor BB for use in
859 inserting new BBs at the end of the function. Do this
860 after the call to split_block above which may split
861 the original exit pred. */
862 exit_pred = EXIT_BLOCK_PTR_FOR_FN (cfun)->prev_bb;
864 FOR_EACH_VEC_ELT (unconverted_simple_returns, i, e)
866 basic_block *pdest_bb;
869 if (BB_PARTITION (e->src) == BB_HOT_PARTITION)
871 pdest_bb = &simple_return_block_hot;
872 pending = pending_edge_hot;
876 pdest_bb = &simple_return_block_cold;
877 pending = pending_edge_cold;
880 if (*pdest_bb == NULL && pending != NULL)
882 emit_return_into_block (true, pending->src);
883 pending->flags &= ~(EDGE_FALLTHRU | EDGE_FAKE);
884 *pdest_bb = pending->src;
886 else if (*pdest_bb == NULL)
891 bb = create_basic_block (NULL, NULL, exit_pred);
892 BB_COPY_PARTITION (bb, e->src);
893 start = emit_jump_insn_after (gen_simple_return (),
895 JUMP_LABEL (start) = simple_return_rtx;
896 emit_barrier_after (start);
899 make_edge (bb, EXIT_BLOCK_PTR_FOR_FN (cfun), 0);
901 redirect_edge_and_branch_force (e, *pdest_bb);
903 unconverted_simple_returns.release ();
906 if (entry_edge != orig_entry_edge)
908 FOR_EACH_EDGE (e, ei, EXIT_BLOCK_PTR_FOR_FN (cfun)->preds)
909 if (EDGE_COUNT (e->src->preds) != 0
910 && (e->flags & EDGE_FAKE) != 0
911 && !bitmap_bit_p (&bb_flags, e->src->index))
913 emit_return_into_block (true, e->src);
914 e->flags &= ~(EDGE_FALLTHRU | EDGE_FAKE);