PR tree-optimization/43833
[official-gcc/alias-decl.git] / gcc / ifcvt.c
blobdcf44b8facf83f0b7b0e2391f02d22eb662c141c
1 /* If-conversion support.
2 Copyright (C) 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2010
3 Free Software Foundation, Inc.
5 This file is part of GCC.
7 GCC is free software; you can redistribute it and/or modify it
8 under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 3, or (at your option)
10 any later version.
12 GCC is distributed in the hope that it will be useful, but WITHOUT
13 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
14 or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public
15 License for more details.
17 You should have received a copy of the GNU General Public License
18 along with GCC; see the file COPYING3. If not see
19 <http://www.gnu.org/licenses/>. */
21 #include "config.h"
22 #include "system.h"
23 #include "coretypes.h"
24 #include "tm.h"
26 #include "rtl.h"
27 #include "regs.h"
28 #include "function.h"
29 #include "flags.h"
30 #include "insn-config.h"
31 #include "recog.h"
32 #include "except.h"
33 #include "hard-reg-set.h"
34 #include "basic-block.h"
35 #include "expr.h"
36 #include "real.h"
37 #include "output.h"
38 #include "optabs.h"
39 #include "toplev.h"
40 #include "tm_p.h"
41 #include "cfgloop.h"
42 #include "target.h"
43 #include "timevar.h"
44 #include "tree-pass.h"
45 #include "df.h"
46 #include "vec.h"
47 #include "vecprim.h"
48 #include "dbgcnt.h"
50 #ifndef HAVE_conditional_move
51 #define HAVE_conditional_move 0
52 #endif
53 #ifndef HAVE_incscc
54 #define HAVE_incscc 0
55 #endif
56 #ifndef HAVE_decscc
57 #define HAVE_decscc 0
58 #endif
59 #ifndef HAVE_trap
60 #define HAVE_trap 0
61 #endif
63 #ifndef MAX_CONDITIONAL_EXECUTE
64 #define MAX_CONDITIONAL_EXECUTE \
65 (BRANCH_COST (optimize_function_for_speed_p (cfun), false) \
66 + 1)
67 #endif
69 #define IFCVT_MULTIPLE_DUMPS 1
71 #define NULL_BLOCK ((basic_block) NULL)
73 /* # of IF-THEN or IF-THEN-ELSE blocks we looked at */
74 static int num_possible_if_blocks;
76 /* # of IF-THEN or IF-THEN-ELSE blocks were converted to conditional
77 execution. */
78 static int num_updated_if_blocks;
80 /* # of changes made. */
81 static int num_true_changes;
83 /* Whether conditional execution changes were made. */
84 static int cond_exec_changed_p;
86 /* Forward references. */
87 static int count_bb_insns (const_basic_block);
88 static bool cheap_bb_rtx_cost_p (const_basic_block, int);
89 static rtx first_active_insn (basic_block);
90 static rtx last_active_insn (basic_block, int);
91 static basic_block block_fallthru (basic_block);
92 static int cond_exec_process_insns (ce_if_block_t *, rtx, rtx, rtx, rtx, int);
93 static rtx cond_exec_get_condition (rtx);
94 static rtx noce_get_condition (rtx, rtx *, bool);
95 static int noce_operand_ok (const_rtx);
96 static void merge_if_block (ce_if_block_t *);
97 static int find_cond_trap (basic_block, edge, edge);
98 static basic_block find_if_header (basic_block, int);
99 static int block_jumps_and_fallthru_p (basic_block, basic_block);
100 static int noce_find_if_block (basic_block, edge, edge, int);
101 static int cond_exec_find_if_block (ce_if_block_t *);
102 static int find_if_case_1 (basic_block, edge, edge);
103 static int find_if_case_2 (basic_block, edge, edge);
104 static int find_memory (rtx *, void *);
105 static int dead_or_predicable (basic_block, basic_block, basic_block,
106 basic_block, int);
107 static void noce_emit_move_insn (rtx, rtx);
108 static rtx block_has_only_trap (basic_block);
110 /* Count the number of non-jump active insns in BB. */
112 static int
113 count_bb_insns (const_basic_block bb)
115 int count = 0;
116 rtx insn = BB_HEAD (bb);
118 while (1)
120 if (CALL_P (insn) || NONJUMP_INSN_P (insn))
121 count++;
123 if (insn == BB_END (bb))
124 break;
125 insn = NEXT_INSN (insn);
128 return count;
131 /* Determine whether the total insn_rtx_cost on non-jump insns in
132 basic block BB is less than MAX_COST. This function returns
133 false if the cost of any instruction could not be estimated. */
135 static bool
136 cheap_bb_rtx_cost_p (const_basic_block bb, int max_cost)
138 int count = 0;
139 rtx insn = BB_HEAD (bb);
140 bool speed = optimize_bb_for_speed_p (bb);
142 while (1)
144 if (NONJUMP_INSN_P (insn))
146 int cost = insn_rtx_cost (PATTERN (insn), speed);
147 if (cost == 0)
148 return false;
150 /* If this instruction is the load or set of a "stack" register,
151 such as a floating point register on x87, then the cost of
152 speculatively executing this insn may need to include
153 the additional cost of popping its result off of the
154 register stack. Unfortunately, correctly recognizing and
155 accounting for this additional overhead is tricky, so for
156 now we simply prohibit such speculative execution. */
157 #ifdef STACK_REGS
159 rtx set = single_set (insn);
160 if (set && STACK_REG_P (SET_DEST (set)))
161 return false;
163 #endif
165 count += cost;
166 if (count >= max_cost)
167 return false;
169 else if (CALL_P (insn))
170 return false;
172 if (insn == BB_END (bb))
173 break;
174 insn = NEXT_INSN (insn);
177 return true;
180 /* Return the first non-jump active insn in the basic block. */
182 static rtx
183 first_active_insn (basic_block bb)
185 rtx insn = BB_HEAD (bb);
187 if (LABEL_P (insn))
189 if (insn == BB_END (bb))
190 return NULL_RTX;
191 insn = NEXT_INSN (insn);
194 while (NOTE_P (insn) || DEBUG_INSN_P (insn))
196 if (insn == BB_END (bb))
197 return NULL_RTX;
198 insn = NEXT_INSN (insn);
201 if (JUMP_P (insn))
202 return NULL_RTX;
204 return insn;
207 /* Return the last non-jump active (non-jump) insn in the basic block. */
209 static rtx
210 last_active_insn (basic_block bb, int skip_use_p)
212 rtx insn = BB_END (bb);
213 rtx head = BB_HEAD (bb);
215 while (NOTE_P (insn)
216 || JUMP_P (insn)
217 || DEBUG_INSN_P (insn)
218 || (skip_use_p
219 && NONJUMP_INSN_P (insn)
220 && GET_CODE (PATTERN (insn)) == USE))
222 if (insn == head)
223 return NULL_RTX;
224 insn = PREV_INSN (insn);
227 if (LABEL_P (insn))
228 return NULL_RTX;
230 return insn;
233 /* Return the basic block reached by falling though the basic block BB. */
235 static basic_block
236 block_fallthru (basic_block bb)
238 edge e;
239 edge_iterator ei;
241 FOR_EACH_EDGE (e, ei, bb->succs)
242 if (e->flags & EDGE_FALLTHRU)
243 break;
245 return (e) ? e->dest : NULL_BLOCK;
248 /* Go through a bunch of insns, converting them to conditional
249 execution format if possible. Return TRUE if all of the non-note
250 insns were processed. */
252 static int
253 cond_exec_process_insns (ce_if_block_t *ce_info ATTRIBUTE_UNUSED,
254 /* if block information */rtx start,
255 /* first insn to look at */rtx end,
256 /* last insn to look at */rtx test,
257 /* conditional execution test */rtx prob_val,
258 /* probability of branch taken. */int mod_ok)
260 int must_be_last = FALSE;
261 rtx insn;
262 rtx xtest;
263 rtx pattern;
265 if (!start || !end)
266 return FALSE;
268 for (insn = start; ; insn = NEXT_INSN (insn))
270 if (NOTE_P (insn) || DEBUG_INSN_P (insn))
271 goto insn_done;
273 gcc_assert(NONJUMP_INSN_P (insn) || CALL_P (insn));
275 /* Remove USE insns that get in the way. */
276 if (reload_completed && GET_CODE (PATTERN (insn)) == USE)
278 /* ??? Ug. Actually unlinking the thing is problematic,
279 given what we'd have to coordinate with our callers. */
280 SET_INSN_DELETED (insn);
281 goto insn_done;
284 /* Last insn wasn't last? */
285 if (must_be_last)
286 return FALSE;
288 if (modified_in_p (test, insn))
290 if (!mod_ok)
291 return FALSE;
292 must_be_last = TRUE;
295 /* Now build the conditional form of the instruction. */
296 pattern = PATTERN (insn);
297 xtest = copy_rtx (test);
299 /* If this is already a COND_EXEC, rewrite the test to be an AND of the
300 two conditions. */
301 if (GET_CODE (pattern) == COND_EXEC)
303 if (GET_MODE (xtest) != GET_MODE (COND_EXEC_TEST (pattern)))
304 return FALSE;
306 xtest = gen_rtx_AND (GET_MODE (xtest), xtest,
307 COND_EXEC_TEST (pattern));
308 pattern = COND_EXEC_CODE (pattern);
311 pattern = gen_rtx_COND_EXEC (VOIDmode, xtest, pattern);
313 /* If the machine needs to modify the insn being conditionally executed,
314 say for example to force a constant integer operand into a temp
315 register, do so here. */
316 #ifdef IFCVT_MODIFY_INSN
317 IFCVT_MODIFY_INSN (ce_info, pattern, insn);
318 if (! pattern)
319 return FALSE;
320 #endif
322 validate_change (insn, &PATTERN (insn), pattern, 1);
324 if (CALL_P (insn) && prob_val)
325 validate_change (insn, &REG_NOTES (insn),
326 alloc_EXPR_LIST (REG_BR_PROB, prob_val,
327 REG_NOTES (insn)), 1);
329 insn_done:
330 if (insn == end)
331 break;
334 return TRUE;
337 /* Return the condition for a jump. Do not do any special processing. */
339 static rtx
340 cond_exec_get_condition (rtx jump)
342 rtx test_if, cond;
344 if (any_condjump_p (jump))
345 test_if = SET_SRC (pc_set (jump));
346 else
347 return NULL_RTX;
348 cond = XEXP (test_if, 0);
350 /* If this branches to JUMP_LABEL when the condition is false,
351 reverse the condition. */
352 if (GET_CODE (XEXP (test_if, 2)) == LABEL_REF
353 && XEXP (XEXP (test_if, 2), 0) == JUMP_LABEL (jump))
355 enum rtx_code rev = reversed_comparison_code (cond, jump);
356 if (rev == UNKNOWN)
357 return NULL_RTX;
359 cond = gen_rtx_fmt_ee (rev, GET_MODE (cond), XEXP (cond, 0),
360 XEXP (cond, 1));
363 return cond;
366 /* Given a simple IF-THEN or IF-THEN-ELSE block, attempt to convert it
367 to conditional execution. Return TRUE if we were successful at
368 converting the block. */
370 static int
371 cond_exec_process_if_block (ce_if_block_t * ce_info,
372 /* if block information */int do_multiple_p)
374 basic_block test_bb = ce_info->test_bb; /* last test block */
375 basic_block then_bb = ce_info->then_bb; /* THEN */
376 basic_block else_bb = ce_info->else_bb; /* ELSE or NULL */
377 rtx test_expr; /* expression in IF_THEN_ELSE that is tested */
378 rtx then_start; /* first insn in THEN block */
379 rtx then_end; /* last insn + 1 in THEN block */
380 rtx else_start = NULL_RTX; /* first insn in ELSE block or NULL */
381 rtx else_end = NULL_RTX; /* last insn + 1 in ELSE block */
382 int max; /* max # of insns to convert. */
383 int then_mod_ok; /* whether conditional mods are ok in THEN */
384 rtx true_expr; /* test for else block insns */
385 rtx false_expr; /* test for then block insns */
386 rtx true_prob_val; /* probability of else block */
387 rtx false_prob_val; /* probability of then block */
388 rtx then_last_head = NULL_RTX; /* Last match at the head of THEN */
389 rtx else_last_head = NULL_RTX; /* Last match at the head of ELSE */
390 rtx then_first_tail = NULL_RTX; /* First match at the tail of THEN */
391 rtx else_first_tail = NULL_RTX; /* First match at the tail of ELSE */
392 int then_n_insns, else_n_insns, n_insns;
393 enum rtx_code false_code;
395 /* If test is comprised of && or || elements, and we've failed at handling
396 all of them together, just use the last test if it is the special case of
397 && elements without an ELSE block. */
398 if (!do_multiple_p && ce_info->num_multiple_test_blocks)
400 if (else_bb || ! ce_info->and_and_p)
401 return FALSE;
403 ce_info->test_bb = test_bb = ce_info->last_test_bb;
404 ce_info->num_multiple_test_blocks = 0;
405 ce_info->num_and_and_blocks = 0;
406 ce_info->num_or_or_blocks = 0;
409 /* Find the conditional jump to the ELSE or JOIN part, and isolate
410 the test. */
411 test_expr = cond_exec_get_condition (BB_END (test_bb));
412 if (! test_expr)
413 return FALSE;
415 /* If the conditional jump is more than just a conditional jump,
416 then we can not do conditional execution conversion on this block. */
417 if (! onlyjump_p (BB_END (test_bb)))
418 return FALSE;
420 /* Collect the bounds of where we're to search, skipping any labels, jumps
421 and notes at the beginning and end of the block. Then count the total
422 number of insns and see if it is small enough to convert. */
423 then_start = first_active_insn (then_bb);
424 then_end = last_active_insn (then_bb, TRUE);
425 then_n_insns = ce_info->num_then_insns = count_bb_insns (then_bb);
426 n_insns = then_n_insns;
427 max = MAX_CONDITIONAL_EXECUTE;
429 if (else_bb)
431 int n_matching;
433 max *= 2;
434 else_start = first_active_insn (else_bb);
435 else_end = last_active_insn (else_bb, TRUE);
436 else_n_insns = ce_info->num_else_insns = count_bb_insns (else_bb);
437 n_insns += else_n_insns;
439 /* Look for matching sequences at the head and tail of the two blocks,
440 and limit the range of insns to be converted if possible. */
441 n_matching = flow_find_cross_jump (then_bb, else_bb,
442 &then_first_tail, &else_first_tail);
443 if (then_first_tail == BB_HEAD (then_bb))
444 then_start = then_end = NULL_RTX;
445 if (else_first_tail == BB_HEAD (else_bb))
446 else_start = else_end = NULL_RTX;
448 if (n_matching > 0)
450 if (then_end)
451 then_end = prev_active_insn (then_first_tail);
452 if (else_end)
453 else_end = prev_active_insn (else_first_tail);
454 n_insns -= 2 * n_matching;
457 if (then_start && else_start)
459 int longest_match = MIN (then_n_insns - n_matching,
460 else_n_insns - n_matching);
461 n_matching
462 = flow_find_head_matching_sequence (then_bb, else_bb,
463 &then_last_head,
464 &else_last_head,
465 longest_match);
467 if (n_matching > 0)
469 rtx insn;
471 /* We won't pass the insns in the head sequence to
472 cond_exec_process_insns, so we need to test them here
473 to make sure that they don't clobber the condition. */
474 for (insn = BB_HEAD (then_bb);
475 insn != NEXT_INSN (then_last_head);
476 insn = NEXT_INSN (insn))
477 if (!LABEL_P (insn) && !NOTE_P (insn)
478 && !DEBUG_INSN_P (insn)
479 && modified_in_p (test_expr, insn))
480 return FALSE;
483 if (then_last_head == then_end)
484 then_start = then_end = NULL_RTX;
485 if (else_last_head == else_end)
486 else_start = else_end = NULL_RTX;
488 if (n_matching > 0)
490 if (then_start)
491 then_start = next_active_insn (then_last_head);
492 if (else_start)
493 else_start = next_active_insn (else_last_head);
494 n_insns -= 2 * n_matching;
499 if (n_insns > max)
500 return FALSE;
502 /* Map test_expr/test_jump into the appropriate MD tests to use on
503 the conditionally executed code. */
505 true_expr = test_expr;
507 false_code = reversed_comparison_code (true_expr, BB_END (test_bb));
508 if (false_code != UNKNOWN)
509 false_expr = gen_rtx_fmt_ee (false_code, GET_MODE (true_expr),
510 XEXP (true_expr, 0), XEXP (true_expr, 1));
511 else
512 false_expr = NULL_RTX;
514 #ifdef IFCVT_MODIFY_TESTS
515 /* If the machine description needs to modify the tests, such as setting a
516 conditional execution register from a comparison, it can do so here. */
517 IFCVT_MODIFY_TESTS (ce_info, true_expr, false_expr);
519 /* See if the conversion failed. */
520 if (!true_expr || !false_expr)
521 goto fail;
522 #endif
524 true_prob_val = find_reg_note (BB_END (test_bb), REG_BR_PROB, NULL_RTX);
525 if (true_prob_val)
527 true_prob_val = XEXP (true_prob_val, 0);
528 false_prob_val = GEN_INT (REG_BR_PROB_BASE - INTVAL (true_prob_val));
530 else
531 false_prob_val = NULL_RTX;
533 /* If we have && or || tests, do them here. These tests are in the adjacent
534 blocks after the first block containing the test. */
535 if (ce_info->num_multiple_test_blocks > 0)
537 basic_block bb = test_bb;
538 basic_block last_test_bb = ce_info->last_test_bb;
540 if (! false_expr)
541 goto fail;
545 rtx start, end;
546 rtx t, f;
547 enum rtx_code f_code;
549 bb = block_fallthru (bb);
550 start = first_active_insn (bb);
551 end = last_active_insn (bb, TRUE);
552 if (start
553 && ! cond_exec_process_insns (ce_info, start, end, false_expr,
554 false_prob_val, FALSE))
555 goto fail;
557 /* If the conditional jump is more than just a conditional jump, then
558 we can not do conditional execution conversion on this block. */
559 if (! onlyjump_p (BB_END (bb)))
560 goto fail;
562 /* Find the conditional jump and isolate the test. */
563 t = cond_exec_get_condition (BB_END (bb));
564 if (! t)
565 goto fail;
567 f_code = reversed_comparison_code (t, BB_END (bb));
568 if (f_code == UNKNOWN)
569 goto fail;
571 f = gen_rtx_fmt_ee (f_code, GET_MODE (t), XEXP (t, 0), XEXP (t, 1));
572 if (ce_info->and_and_p)
574 t = gen_rtx_AND (GET_MODE (t), true_expr, t);
575 f = gen_rtx_IOR (GET_MODE (t), false_expr, f);
577 else
579 t = gen_rtx_IOR (GET_MODE (t), true_expr, t);
580 f = gen_rtx_AND (GET_MODE (t), false_expr, f);
583 /* If the machine description needs to modify the tests, such as
584 setting a conditional execution register from a comparison, it can
585 do so here. */
586 #ifdef IFCVT_MODIFY_MULTIPLE_TESTS
587 IFCVT_MODIFY_MULTIPLE_TESTS (ce_info, bb, t, f);
589 /* See if the conversion failed. */
590 if (!t || !f)
591 goto fail;
592 #endif
594 true_expr = t;
595 false_expr = f;
597 while (bb != last_test_bb);
600 /* For IF-THEN-ELSE blocks, we don't allow modifications of the test
601 on then THEN block. */
602 then_mod_ok = (else_bb == NULL_BLOCK);
604 /* Go through the THEN and ELSE blocks converting the insns if possible
605 to conditional execution. */
607 if (then_end
608 && (! false_expr
609 || ! cond_exec_process_insns (ce_info, then_start, then_end,
610 false_expr, false_prob_val,
611 then_mod_ok)))
612 goto fail;
614 if (else_bb && else_end
615 && ! cond_exec_process_insns (ce_info, else_start, else_end,
616 true_expr, true_prob_val, TRUE))
617 goto fail;
619 /* If we cannot apply the changes, fail. Do not go through the normal fail
620 processing, since apply_change_group will call cancel_changes. */
621 if (! apply_change_group ())
623 #ifdef IFCVT_MODIFY_CANCEL
624 /* Cancel any machine dependent changes. */
625 IFCVT_MODIFY_CANCEL (ce_info);
626 #endif
627 return FALSE;
630 #ifdef IFCVT_MODIFY_FINAL
631 /* Do any machine dependent final modifications. */
632 IFCVT_MODIFY_FINAL (ce_info);
633 #endif
635 /* Conversion succeeded. */
636 if (dump_file)
637 fprintf (dump_file, "%d insn%s converted to conditional execution.\n",
638 n_insns, (n_insns == 1) ? " was" : "s were");
640 /* Merge the blocks! If we had matching sequences, make sure to delete one
641 copy at the appropriate location first: delete the copy in the THEN branch
642 for a tail sequence so that the remaining one is executed last for both
643 branches, and delete the copy in the ELSE branch for a head sequence so
644 that the remaining one is executed first for both branches. */
645 if (then_first_tail)
647 rtx from = then_first_tail;
648 if (!INSN_P (from))
649 from = next_active_insn (from);
650 delete_insn_chain (from, BB_END (then_bb), false);
652 if (else_last_head)
653 delete_insn_chain (first_active_insn (else_bb), else_last_head, false);
655 merge_if_block (ce_info);
656 cond_exec_changed_p = TRUE;
657 return TRUE;
659 fail:
660 #ifdef IFCVT_MODIFY_CANCEL
661 /* Cancel any machine dependent changes. */
662 IFCVT_MODIFY_CANCEL (ce_info);
663 #endif
665 cancel_changes (0);
666 return FALSE;
669 /* Used by noce_process_if_block to communicate with its subroutines.
671 The subroutines know that A and B may be evaluated freely. They
672 know that X is a register. They should insert new instructions
673 before cond_earliest. */
675 struct noce_if_info
677 /* The basic blocks that make up the IF-THEN-{ELSE-,}JOIN block. */
678 basic_block test_bb, then_bb, else_bb, join_bb;
680 /* The jump that ends TEST_BB. */
681 rtx jump;
683 /* The jump condition. */
684 rtx cond;
686 /* New insns should be inserted before this one. */
687 rtx cond_earliest;
689 /* Insns in the THEN and ELSE block. There is always just this
690 one insns in those blocks. The insns are single_set insns.
691 If there was no ELSE block, INSN_B is the last insn before
692 COND_EARLIEST, or NULL_RTX. In the former case, the insn
693 operands are still valid, as if INSN_B was moved down below
694 the jump. */
695 rtx insn_a, insn_b;
697 /* The SET_SRC of INSN_A and INSN_B. */
698 rtx a, b;
700 /* The SET_DEST of INSN_A. */
701 rtx x;
703 /* True if this if block is not canonical. In the canonical form of
704 if blocks, the THEN_BB is the block reached via the fallthru edge
705 from TEST_BB. For the noce transformations, we allow the symmetric
706 form as well. */
707 bool then_else_reversed;
709 /* Estimated cost of the particular branch instruction. */
710 int branch_cost;
713 static rtx noce_emit_store_flag (struct noce_if_info *, rtx, int, int);
714 static int noce_try_move (struct noce_if_info *);
715 static int noce_try_store_flag (struct noce_if_info *);
716 static int noce_try_addcc (struct noce_if_info *);
717 static int noce_try_store_flag_constants (struct noce_if_info *);
718 static int noce_try_store_flag_mask (struct noce_if_info *);
719 static rtx noce_emit_cmove (struct noce_if_info *, rtx, enum rtx_code, rtx,
720 rtx, rtx, rtx);
721 static int noce_try_cmove (struct noce_if_info *);
722 static int noce_try_cmove_arith (struct noce_if_info *);
723 static rtx noce_get_alt_condition (struct noce_if_info *, rtx, rtx *);
724 static int noce_try_minmax (struct noce_if_info *);
725 static int noce_try_abs (struct noce_if_info *);
726 static int noce_try_sign_mask (struct noce_if_info *);
728 /* Helper function for noce_try_store_flag*. */
730 static rtx
731 noce_emit_store_flag (struct noce_if_info *if_info, rtx x, int reversep,
732 int normalize)
734 rtx cond = if_info->cond;
735 int cond_complex;
736 enum rtx_code code;
738 cond_complex = (! general_operand (XEXP (cond, 0), VOIDmode)
739 || ! general_operand (XEXP (cond, 1), VOIDmode));
741 /* If earliest == jump, or when the condition is complex, try to
742 build the store_flag insn directly. */
744 if (cond_complex)
746 rtx set = pc_set (if_info->jump);
747 cond = XEXP (SET_SRC (set), 0);
748 if (GET_CODE (XEXP (SET_SRC (set), 2)) == LABEL_REF
749 && XEXP (XEXP (SET_SRC (set), 2), 0) == JUMP_LABEL (if_info->jump))
750 reversep = !reversep;
751 if (if_info->then_else_reversed)
752 reversep = !reversep;
755 if (reversep)
756 code = reversed_comparison_code (cond, if_info->jump);
757 else
758 code = GET_CODE (cond);
760 if ((if_info->cond_earliest == if_info->jump || cond_complex)
761 && (normalize == 0 || STORE_FLAG_VALUE == normalize))
763 rtx tmp;
765 tmp = gen_rtx_fmt_ee (code, GET_MODE (x), XEXP (cond, 0),
766 XEXP (cond, 1));
767 tmp = gen_rtx_SET (VOIDmode, x, tmp);
769 start_sequence ();
770 tmp = emit_insn (tmp);
772 if (recog_memoized (tmp) >= 0)
774 tmp = get_insns ();
775 end_sequence ();
776 emit_insn (tmp);
778 if_info->cond_earliest = if_info->jump;
780 return x;
783 end_sequence ();
786 /* Don't even try if the comparison operands or the mode of X are weird. */
787 if (cond_complex || !SCALAR_INT_MODE_P (GET_MODE (x)))
788 return NULL_RTX;
790 return emit_store_flag (x, code, XEXP (cond, 0),
791 XEXP (cond, 1), VOIDmode,
792 (code == LTU || code == LEU
793 || code == GEU || code == GTU), normalize);
796 /* Emit instruction to move an rtx, possibly into STRICT_LOW_PART.
797 X is the destination/target and Y is the value to copy. */
799 static void
800 noce_emit_move_insn (rtx x, rtx y)
802 enum machine_mode outmode;
803 rtx outer, inner;
804 int bitpos;
806 if (GET_CODE (x) != STRICT_LOW_PART)
808 rtx seq, insn, target;
809 optab ot;
811 start_sequence ();
812 /* Check that the SET_SRC is reasonable before calling emit_move_insn,
813 otherwise construct a suitable SET pattern ourselves. */
814 insn = (OBJECT_P (y) || CONSTANT_P (y) || GET_CODE (y) == SUBREG)
815 ? emit_move_insn (x, y)
816 : emit_insn (gen_rtx_SET (VOIDmode, x, y));
817 seq = get_insns ();
818 end_sequence ();
820 if (recog_memoized (insn) <= 0)
822 if (GET_CODE (x) == ZERO_EXTRACT)
824 rtx op = XEXP (x, 0);
825 unsigned HOST_WIDE_INT size = INTVAL (XEXP (x, 1));
826 unsigned HOST_WIDE_INT start = INTVAL (XEXP (x, 2));
828 /* store_bit_field expects START to be relative to
829 BYTES_BIG_ENDIAN and adjusts this value for machines with
830 BITS_BIG_ENDIAN != BYTES_BIG_ENDIAN. In order to be able to
831 invoke store_bit_field again it is necessary to have the START
832 value from the first call. */
833 if (BITS_BIG_ENDIAN != BYTES_BIG_ENDIAN)
835 if (MEM_P (op))
836 start = BITS_PER_UNIT - start - size;
837 else
839 gcc_assert (REG_P (op));
840 start = BITS_PER_WORD - start - size;
844 gcc_assert (start < (MEM_P (op) ? BITS_PER_UNIT : BITS_PER_WORD));
845 store_bit_field (op, size, start, GET_MODE (x), y);
846 return;
849 switch (GET_RTX_CLASS (GET_CODE (y)))
851 case RTX_UNARY:
852 ot = code_to_optab[GET_CODE (y)];
853 if (ot)
855 start_sequence ();
856 target = expand_unop (GET_MODE (y), ot, XEXP (y, 0), x, 0);
857 if (target != NULL_RTX)
859 if (target != x)
860 emit_move_insn (x, target);
861 seq = get_insns ();
863 end_sequence ();
865 break;
867 case RTX_BIN_ARITH:
868 case RTX_COMM_ARITH:
869 ot = code_to_optab[GET_CODE (y)];
870 if (ot)
872 start_sequence ();
873 target = expand_binop (GET_MODE (y), ot,
874 XEXP (y, 0), XEXP (y, 1),
875 x, 0, OPTAB_DIRECT);
876 if (target != NULL_RTX)
878 if (target != x)
879 emit_move_insn (x, target);
880 seq = get_insns ();
882 end_sequence ();
884 break;
886 default:
887 break;
891 emit_insn (seq);
892 return;
895 outer = XEXP (x, 0);
896 inner = XEXP (outer, 0);
897 outmode = GET_MODE (outer);
898 bitpos = SUBREG_BYTE (outer) * BITS_PER_UNIT;
899 store_bit_field (inner, GET_MODE_BITSIZE (outmode), bitpos, outmode, y);
902 /* Return sequence of instructions generated by if conversion. This
903 function calls end_sequence() to end the current stream, ensures
904 that are instructions are unshared, recognizable non-jump insns.
905 On failure, this function returns a NULL_RTX. */
907 static rtx
908 end_ifcvt_sequence (struct noce_if_info *if_info)
910 rtx insn;
911 rtx seq = get_insns ();
913 set_used_flags (if_info->x);
914 set_used_flags (if_info->cond);
915 unshare_all_rtl_in_chain (seq);
916 end_sequence ();
918 /* Make sure that all of the instructions emitted are recognizable,
919 and that we haven't introduced a new jump instruction.
920 As an exercise for the reader, build a general mechanism that
921 allows proper placement of required clobbers. */
922 for (insn = seq; insn; insn = NEXT_INSN (insn))
923 if (JUMP_P (insn)
924 || recog_memoized (insn) == -1)
925 return NULL_RTX;
927 return seq;
930 /* Convert "if (a != b) x = a; else x = b" into "x = a" and
931 "if (a == b) x = a; else x = b" into "x = b". */
933 static int
934 noce_try_move (struct noce_if_info *if_info)
936 rtx cond = if_info->cond;
937 enum rtx_code code = GET_CODE (cond);
938 rtx y, seq;
940 if (code != NE && code != EQ)
941 return FALSE;
943 /* This optimization isn't valid if either A or B could be a NaN
944 or a signed zero. */
945 if (HONOR_NANS (GET_MODE (if_info->x))
946 || HONOR_SIGNED_ZEROS (GET_MODE (if_info->x)))
947 return FALSE;
949 /* Check whether the operands of the comparison are A and in
950 either order. */
951 if ((rtx_equal_p (if_info->a, XEXP (cond, 0))
952 && rtx_equal_p (if_info->b, XEXP (cond, 1)))
953 || (rtx_equal_p (if_info->a, XEXP (cond, 1))
954 && rtx_equal_p (if_info->b, XEXP (cond, 0))))
956 y = (code == EQ) ? if_info->a : if_info->b;
958 /* Avoid generating the move if the source is the destination. */
959 if (! rtx_equal_p (if_info->x, y))
961 start_sequence ();
962 noce_emit_move_insn (if_info->x, y);
963 seq = end_ifcvt_sequence (if_info);
964 if (!seq)
965 return FALSE;
967 emit_insn_before_setloc (seq, if_info->jump,
968 INSN_LOCATOR (if_info->insn_a));
970 return TRUE;
972 return FALSE;
975 /* Convert "if (test) x = 1; else x = 0".
977 Only try 0 and STORE_FLAG_VALUE here. Other combinations will be
978 tried in noce_try_store_flag_constants after noce_try_cmove has had
979 a go at the conversion. */
981 static int
982 noce_try_store_flag (struct noce_if_info *if_info)
984 int reversep;
985 rtx target, seq;
987 if (CONST_INT_P (if_info->b)
988 && INTVAL (if_info->b) == STORE_FLAG_VALUE
989 && if_info->a == const0_rtx)
990 reversep = 0;
991 else if (if_info->b == const0_rtx
992 && CONST_INT_P (if_info->a)
993 && INTVAL (if_info->a) == STORE_FLAG_VALUE
994 && (reversed_comparison_code (if_info->cond, if_info->jump)
995 != UNKNOWN))
996 reversep = 1;
997 else
998 return FALSE;
1000 start_sequence ();
1002 target = noce_emit_store_flag (if_info, if_info->x, reversep, 0);
1003 if (target)
1005 if (target != if_info->x)
1006 noce_emit_move_insn (if_info->x, target);
1008 seq = end_ifcvt_sequence (if_info);
1009 if (! seq)
1010 return FALSE;
1012 emit_insn_before_setloc (seq, if_info->jump,
1013 INSN_LOCATOR (if_info->insn_a));
1014 return TRUE;
1016 else
1018 end_sequence ();
1019 return FALSE;
1023 /* Convert "if (test) x = a; else x = b", for A and B constant. */
1025 static int
1026 noce_try_store_flag_constants (struct noce_if_info *if_info)
1028 rtx target, seq;
1029 int reversep;
1030 HOST_WIDE_INT itrue, ifalse, diff, tmp;
1031 int normalize, can_reverse;
1032 enum machine_mode mode;
1034 if (CONST_INT_P (if_info->a)
1035 && CONST_INT_P (if_info->b))
1037 mode = GET_MODE (if_info->x);
1038 ifalse = INTVAL (if_info->a);
1039 itrue = INTVAL (if_info->b);
1041 /* Make sure we can represent the difference between the two values. */
1042 if ((itrue - ifalse > 0)
1043 != ((ifalse < 0) != (itrue < 0) ? ifalse < 0 : ifalse < itrue))
1044 return FALSE;
1046 diff = trunc_int_for_mode (itrue - ifalse, mode);
1048 can_reverse = (reversed_comparison_code (if_info->cond, if_info->jump)
1049 != UNKNOWN);
1051 reversep = 0;
1052 if (diff == STORE_FLAG_VALUE || diff == -STORE_FLAG_VALUE)
1053 normalize = 0;
1054 else if (ifalse == 0 && exact_log2 (itrue) >= 0
1055 && (STORE_FLAG_VALUE == 1
1056 || if_info->branch_cost >= 2))
1057 normalize = 1;
1058 else if (itrue == 0 && exact_log2 (ifalse) >= 0 && can_reverse
1059 && (STORE_FLAG_VALUE == 1 || if_info->branch_cost >= 2))
1060 normalize = 1, reversep = 1;
1061 else if (itrue == -1
1062 && (STORE_FLAG_VALUE == -1
1063 || if_info->branch_cost >= 2))
1064 normalize = -1;
1065 else if (ifalse == -1 && can_reverse
1066 && (STORE_FLAG_VALUE == -1 || if_info->branch_cost >= 2))
1067 normalize = -1, reversep = 1;
1068 else if ((if_info->branch_cost >= 2 && STORE_FLAG_VALUE == -1)
1069 || if_info->branch_cost >= 3)
1070 normalize = -1;
1071 else
1072 return FALSE;
1074 if (reversep)
1076 tmp = itrue; itrue = ifalse; ifalse = tmp;
1077 diff = trunc_int_for_mode (-diff, mode);
1080 start_sequence ();
1081 target = noce_emit_store_flag (if_info, if_info->x, reversep, normalize);
1082 if (! target)
1084 end_sequence ();
1085 return FALSE;
1088 /* if (test) x = 3; else x = 4;
1089 => x = 3 + (test == 0); */
1090 if (diff == STORE_FLAG_VALUE || diff == -STORE_FLAG_VALUE)
1092 target = expand_simple_binop (mode,
1093 (diff == STORE_FLAG_VALUE
1094 ? PLUS : MINUS),
1095 GEN_INT (ifalse), target, if_info->x, 0,
1096 OPTAB_WIDEN);
1099 /* if (test) x = 8; else x = 0;
1100 => x = (test != 0) << 3; */
1101 else if (ifalse == 0 && (tmp = exact_log2 (itrue)) >= 0)
1103 target = expand_simple_binop (mode, ASHIFT,
1104 target, GEN_INT (tmp), if_info->x, 0,
1105 OPTAB_WIDEN);
1108 /* if (test) x = -1; else x = b;
1109 => x = -(test != 0) | b; */
1110 else if (itrue == -1)
1112 target = expand_simple_binop (mode, IOR,
1113 target, GEN_INT (ifalse), if_info->x, 0,
1114 OPTAB_WIDEN);
1117 /* if (test) x = a; else x = b;
1118 => x = (-(test != 0) & (b - a)) + a; */
1119 else
1121 target = expand_simple_binop (mode, AND,
1122 target, GEN_INT (diff), if_info->x, 0,
1123 OPTAB_WIDEN);
1124 if (target)
1125 target = expand_simple_binop (mode, PLUS,
1126 target, GEN_INT (ifalse),
1127 if_info->x, 0, OPTAB_WIDEN);
1130 if (! target)
1132 end_sequence ();
1133 return FALSE;
1136 if (target != if_info->x)
1137 noce_emit_move_insn (if_info->x, target);
1139 seq = end_ifcvt_sequence (if_info);
1140 if (!seq)
1141 return FALSE;
1143 emit_insn_before_setloc (seq, if_info->jump,
1144 INSN_LOCATOR (if_info->insn_a));
1145 return TRUE;
1148 return FALSE;
1151 /* Convert "if (test) foo++" into "foo += (test != 0)", and
1152 similarly for "foo--". */
1154 static int
1155 noce_try_addcc (struct noce_if_info *if_info)
1157 rtx target, seq;
1158 int subtract, normalize;
1160 if (GET_CODE (if_info->a) == PLUS
1161 && rtx_equal_p (XEXP (if_info->a, 0), if_info->b)
1162 && (reversed_comparison_code (if_info->cond, if_info->jump)
1163 != UNKNOWN))
1165 rtx cond = if_info->cond;
1166 enum rtx_code code = reversed_comparison_code (cond, if_info->jump);
1168 /* First try to use addcc pattern. */
1169 if (general_operand (XEXP (cond, 0), VOIDmode)
1170 && general_operand (XEXP (cond, 1), VOIDmode))
1172 start_sequence ();
1173 target = emit_conditional_add (if_info->x, code,
1174 XEXP (cond, 0),
1175 XEXP (cond, 1),
1176 VOIDmode,
1177 if_info->b,
1178 XEXP (if_info->a, 1),
1179 GET_MODE (if_info->x),
1180 (code == LTU || code == GEU
1181 || code == LEU || code == GTU));
1182 if (target)
1184 if (target != if_info->x)
1185 noce_emit_move_insn (if_info->x, target);
1187 seq = end_ifcvt_sequence (if_info);
1188 if (!seq)
1189 return FALSE;
1191 emit_insn_before_setloc (seq, if_info->jump,
1192 INSN_LOCATOR (if_info->insn_a));
1193 return TRUE;
1195 end_sequence ();
1198 /* If that fails, construct conditional increment or decrement using
1199 setcc. */
1200 if (if_info->branch_cost >= 2
1201 && (XEXP (if_info->a, 1) == const1_rtx
1202 || XEXP (if_info->a, 1) == constm1_rtx))
1204 start_sequence ();
1205 if (STORE_FLAG_VALUE == INTVAL (XEXP (if_info->a, 1)))
1206 subtract = 0, normalize = 0;
1207 else if (-STORE_FLAG_VALUE == INTVAL (XEXP (if_info->a, 1)))
1208 subtract = 1, normalize = 0;
1209 else
1210 subtract = 0, normalize = INTVAL (XEXP (if_info->a, 1));
1213 target = noce_emit_store_flag (if_info,
1214 gen_reg_rtx (GET_MODE (if_info->x)),
1215 1, normalize);
1217 if (target)
1218 target = expand_simple_binop (GET_MODE (if_info->x),
1219 subtract ? MINUS : PLUS,
1220 if_info->b, target, if_info->x,
1221 0, OPTAB_WIDEN);
1222 if (target)
1224 if (target != if_info->x)
1225 noce_emit_move_insn (if_info->x, target);
1227 seq = end_ifcvt_sequence (if_info);
1228 if (!seq)
1229 return FALSE;
1231 emit_insn_before_setloc (seq, if_info->jump,
1232 INSN_LOCATOR (if_info->insn_a));
1233 return TRUE;
1235 end_sequence ();
1239 return FALSE;
1242 /* Convert "if (test) x = 0;" to "x &= -(test == 0);" */
1244 static int
1245 noce_try_store_flag_mask (struct noce_if_info *if_info)
1247 rtx target, seq;
1248 int reversep;
1250 reversep = 0;
1251 if ((if_info->branch_cost >= 2
1252 || STORE_FLAG_VALUE == -1)
1253 && ((if_info->a == const0_rtx
1254 && rtx_equal_p (if_info->b, if_info->x))
1255 || ((reversep = (reversed_comparison_code (if_info->cond,
1256 if_info->jump)
1257 != UNKNOWN))
1258 && if_info->b == const0_rtx
1259 && rtx_equal_p (if_info->a, if_info->x))))
1261 start_sequence ();
1262 target = noce_emit_store_flag (if_info,
1263 gen_reg_rtx (GET_MODE (if_info->x)),
1264 reversep, -1);
1265 if (target)
1266 target = expand_simple_binop (GET_MODE (if_info->x), AND,
1267 if_info->x,
1268 target, if_info->x, 0,
1269 OPTAB_WIDEN);
1271 if (target)
1273 if (target != if_info->x)
1274 noce_emit_move_insn (if_info->x, target);
1276 seq = end_ifcvt_sequence (if_info);
1277 if (!seq)
1278 return FALSE;
1280 emit_insn_before_setloc (seq, if_info->jump,
1281 INSN_LOCATOR (if_info->insn_a));
1282 return TRUE;
1285 end_sequence ();
1288 return FALSE;
1291 /* Helper function for noce_try_cmove and noce_try_cmove_arith. */
1293 static rtx
1294 noce_emit_cmove (struct noce_if_info *if_info, rtx x, enum rtx_code code,
1295 rtx cmp_a, rtx cmp_b, rtx vfalse, rtx vtrue)
1297 /* If earliest == jump, try to build the cmove insn directly.
1298 This is helpful when combine has created some complex condition
1299 (like for alpha's cmovlbs) that we can't hope to regenerate
1300 through the normal interface. */
1302 if (if_info->cond_earliest == if_info->jump)
1304 rtx tmp;
1306 tmp = gen_rtx_fmt_ee (code, GET_MODE (if_info->cond), cmp_a, cmp_b);
1307 tmp = gen_rtx_IF_THEN_ELSE (GET_MODE (x), tmp, vtrue, vfalse);
1308 tmp = gen_rtx_SET (VOIDmode, x, tmp);
1310 start_sequence ();
1311 tmp = emit_insn (tmp);
1313 if (recog_memoized (tmp) >= 0)
1315 tmp = get_insns ();
1316 end_sequence ();
1317 emit_insn (tmp);
1319 return x;
1322 end_sequence ();
1325 /* Don't even try if the comparison operands are weird. */
1326 if (! general_operand (cmp_a, GET_MODE (cmp_a))
1327 || ! general_operand (cmp_b, GET_MODE (cmp_b)))
1328 return NULL_RTX;
1330 #if HAVE_conditional_move
1331 return emit_conditional_move (x, code, cmp_a, cmp_b, VOIDmode,
1332 vtrue, vfalse, GET_MODE (x),
1333 (code == LTU || code == GEU
1334 || code == LEU || code == GTU));
1335 #else
1336 /* We'll never get here, as noce_process_if_block doesn't call the
1337 functions involved. Ifdef code, however, should be discouraged
1338 because it leads to typos in the code not selected. However,
1339 emit_conditional_move won't exist either. */
1340 return NULL_RTX;
1341 #endif
1344 /* Try only simple constants and registers here. More complex cases
1345 are handled in noce_try_cmove_arith after noce_try_store_flag_arith
1346 has had a go at it. */
1348 static int
1349 noce_try_cmove (struct noce_if_info *if_info)
1351 enum rtx_code code;
1352 rtx target, seq;
1354 if ((CONSTANT_P (if_info->a) || register_operand (if_info->a, VOIDmode))
1355 && (CONSTANT_P (if_info->b) || register_operand (if_info->b, VOIDmode)))
1357 start_sequence ();
1359 code = GET_CODE (if_info->cond);
1360 target = noce_emit_cmove (if_info, if_info->x, code,
1361 XEXP (if_info->cond, 0),
1362 XEXP (if_info->cond, 1),
1363 if_info->a, if_info->b);
1365 if (target)
1367 if (target != if_info->x)
1368 noce_emit_move_insn (if_info->x, target);
1370 seq = end_ifcvt_sequence (if_info);
1371 if (!seq)
1372 return FALSE;
1374 emit_insn_before_setloc (seq, if_info->jump,
1375 INSN_LOCATOR (if_info->insn_a));
1376 return TRUE;
1378 else
1380 end_sequence ();
1381 return FALSE;
1385 return FALSE;
1388 /* Try more complex cases involving conditional_move. */
1390 static int
1391 noce_try_cmove_arith (struct noce_if_info *if_info)
1393 rtx a = if_info->a;
1394 rtx b = if_info->b;
1395 rtx x = if_info->x;
1396 rtx orig_a, orig_b;
1397 rtx insn_a, insn_b;
1398 rtx tmp, target;
1399 int is_mem = 0;
1400 int insn_cost;
1401 enum rtx_code code;
1403 /* A conditional move from two memory sources is equivalent to a
1404 conditional on their addresses followed by a load. Don't do this
1405 early because it'll screw alias analysis. Note that we've
1406 already checked for no side effects. */
1407 /* ??? FIXME: Magic number 5. */
1408 if (cse_not_expected
1409 && MEM_P (a) && MEM_P (b)
1410 && MEM_ADDR_SPACE (a) == MEM_ADDR_SPACE (b)
1411 && if_info->branch_cost >= 5)
1413 enum machine_mode address_mode
1414 = targetm.addr_space.address_mode (MEM_ADDR_SPACE (a));
1416 a = XEXP (a, 0);
1417 b = XEXP (b, 0);
1418 x = gen_reg_rtx (address_mode);
1419 is_mem = 1;
1422 /* ??? We could handle this if we knew that a load from A or B could
1423 not fault. This is also true if we've already loaded
1424 from the address along the path from ENTRY. */
1425 else if (may_trap_p (a) || may_trap_p (b))
1426 return FALSE;
1428 /* if (test) x = a + b; else x = c - d;
1429 => y = a + b;
1430 x = c - d;
1431 if (test)
1432 x = y;
1435 code = GET_CODE (if_info->cond);
1436 insn_a = if_info->insn_a;
1437 insn_b = if_info->insn_b;
1439 /* Total insn_rtx_cost should be smaller than branch cost. Exit
1440 if insn_rtx_cost can't be estimated. */
1441 if (insn_a)
1443 insn_cost
1444 = insn_rtx_cost (PATTERN (insn_a),
1445 optimize_bb_for_speed_p (BLOCK_FOR_INSN (insn_a)));
1446 if (insn_cost == 0 || insn_cost > COSTS_N_INSNS (if_info->branch_cost))
1447 return FALSE;
1449 else
1450 insn_cost = 0;
1452 if (insn_b)
1454 insn_cost
1455 += insn_rtx_cost (PATTERN (insn_b),
1456 optimize_bb_for_speed_p (BLOCK_FOR_INSN (insn_b)));
1457 if (insn_cost == 0 || insn_cost > COSTS_N_INSNS (if_info->branch_cost))
1458 return FALSE;
1461 /* Possibly rearrange operands to make things come out more natural. */
1462 if (reversed_comparison_code (if_info->cond, if_info->jump) != UNKNOWN)
1464 int reversep = 0;
1465 if (rtx_equal_p (b, x))
1466 reversep = 1;
1467 else if (general_operand (b, GET_MODE (b)))
1468 reversep = 1;
1470 if (reversep)
1472 code = reversed_comparison_code (if_info->cond, if_info->jump);
1473 tmp = a, a = b, b = tmp;
1474 tmp = insn_a, insn_a = insn_b, insn_b = tmp;
1478 start_sequence ();
1480 orig_a = a;
1481 orig_b = b;
1483 /* If either operand is complex, load it into a register first.
1484 The best way to do this is to copy the original insn. In this
1485 way we preserve any clobbers etc that the insn may have had.
1486 This is of course not possible in the IS_MEM case. */
1487 if (! general_operand (a, GET_MODE (a)))
1489 rtx set;
1491 if (is_mem)
1493 tmp = gen_reg_rtx (GET_MODE (a));
1494 tmp = emit_insn (gen_rtx_SET (VOIDmode, tmp, a));
1496 else if (! insn_a)
1497 goto end_seq_and_fail;
1498 else
1500 a = gen_reg_rtx (GET_MODE (a));
1501 tmp = copy_rtx (insn_a);
1502 set = single_set (tmp);
1503 SET_DEST (set) = a;
1504 tmp = emit_insn (PATTERN (tmp));
1506 if (recog_memoized (tmp) < 0)
1507 goto end_seq_and_fail;
1509 if (! general_operand (b, GET_MODE (b)))
1511 rtx set, last;
1513 if (is_mem)
1515 tmp = gen_reg_rtx (GET_MODE (b));
1516 tmp = gen_rtx_SET (VOIDmode, tmp, b);
1518 else if (! insn_b)
1519 goto end_seq_and_fail;
1520 else
1522 b = gen_reg_rtx (GET_MODE (b));
1523 tmp = copy_rtx (insn_b);
1524 set = single_set (tmp);
1525 SET_DEST (set) = b;
1526 tmp = PATTERN (tmp);
1529 /* If insn to set up A clobbers any registers B depends on, try to
1530 swap insn that sets up A with the one that sets up B. If even
1531 that doesn't help, punt. */
1532 last = get_last_insn ();
1533 if (last && modified_in_p (orig_b, last))
1535 tmp = emit_insn_before (tmp, get_insns ());
1536 if (modified_in_p (orig_a, tmp))
1537 goto end_seq_and_fail;
1539 else
1540 tmp = emit_insn (tmp);
1542 if (recog_memoized (tmp) < 0)
1543 goto end_seq_and_fail;
1546 target = noce_emit_cmove (if_info, x, code, XEXP (if_info->cond, 0),
1547 XEXP (if_info->cond, 1), a, b);
1549 if (! target)
1550 goto end_seq_and_fail;
1552 /* If we're handling a memory for above, emit the load now. */
1553 if (is_mem)
1555 tmp = gen_rtx_MEM (GET_MODE (if_info->x), target);
1557 /* Copy over flags as appropriate. */
1558 if (MEM_VOLATILE_P (if_info->a) || MEM_VOLATILE_P (if_info->b))
1559 MEM_VOLATILE_P (tmp) = 1;
1560 if (MEM_IN_STRUCT_P (if_info->a) && MEM_IN_STRUCT_P (if_info->b))
1561 MEM_IN_STRUCT_P (tmp) = 1;
1562 if (MEM_SCALAR_P (if_info->a) && MEM_SCALAR_P (if_info->b))
1563 MEM_SCALAR_P (tmp) = 1;
1564 if (MEM_ALIAS_SET (if_info->a) == MEM_ALIAS_SET (if_info->b))
1565 set_mem_alias_set (tmp, MEM_ALIAS_SET (if_info->a));
1566 set_mem_align (tmp,
1567 MIN (MEM_ALIGN (if_info->a), MEM_ALIGN (if_info->b)));
1569 gcc_assert (MEM_ADDR_SPACE (if_info->a) == MEM_ADDR_SPACE (if_info->b));
1570 set_mem_addr_space (tmp, MEM_ADDR_SPACE (if_info->a));
1572 noce_emit_move_insn (if_info->x, tmp);
1574 else if (target != x)
1575 noce_emit_move_insn (x, target);
1577 tmp = end_ifcvt_sequence (if_info);
1578 if (!tmp)
1579 return FALSE;
1581 emit_insn_before_setloc (tmp, if_info->jump, INSN_LOCATOR (if_info->insn_a));
1582 return TRUE;
1584 end_seq_and_fail:
1585 end_sequence ();
1586 return FALSE;
1589 /* For most cases, the simplified condition we found is the best
1590 choice, but this is not the case for the min/max/abs transforms.
1591 For these we wish to know that it is A or B in the condition. */
1593 static rtx
1594 noce_get_alt_condition (struct noce_if_info *if_info, rtx target,
1595 rtx *earliest)
1597 rtx cond, set, insn;
1598 int reverse;
1600 /* If target is already mentioned in the known condition, return it. */
1601 if (reg_mentioned_p (target, if_info->cond))
1603 *earliest = if_info->cond_earliest;
1604 return if_info->cond;
1607 set = pc_set (if_info->jump);
1608 cond = XEXP (SET_SRC (set), 0);
1609 reverse
1610 = GET_CODE (XEXP (SET_SRC (set), 2)) == LABEL_REF
1611 && XEXP (XEXP (SET_SRC (set), 2), 0) == JUMP_LABEL (if_info->jump);
1612 if (if_info->then_else_reversed)
1613 reverse = !reverse;
1615 /* If we're looking for a constant, try to make the conditional
1616 have that constant in it. There are two reasons why it may
1617 not have the constant we want:
1619 1. GCC may have needed to put the constant in a register, because
1620 the target can't compare directly against that constant. For
1621 this case, we look for a SET immediately before the comparison
1622 that puts a constant in that register.
1624 2. GCC may have canonicalized the conditional, for example
1625 replacing "if x < 4" with "if x <= 3". We can undo that (or
1626 make equivalent types of changes) to get the constants we need
1627 if they're off by one in the right direction. */
1629 if (CONST_INT_P (target))
1631 enum rtx_code code = GET_CODE (if_info->cond);
1632 rtx op_a = XEXP (if_info->cond, 0);
1633 rtx op_b = XEXP (if_info->cond, 1);
1634 rtx prev_insn;
1636 /* First, look to see if we put a constant in a register. */
1637 prev_insn = prev_nonnote_insn (if_info->cond_earliest);
1638 if (prev_insn
1639 && BLOCK_FOR_INSN (prev_insn)
1640 == BLOCK_FOR_INSN (if_info->cond_earliest)
1641 && INSN_P (prev_insn)
1642 && GET_CODE (PATTERN (prev_insn)) == SET)
1644 rtx src = find_reg_equal_equiv_note (prev_insn);
1645 if (!src)
1646 src = SET_SRC (PATTERN (prev_insn));
1647 if (CONST_INT_P (src))
1649 if (rtx_equal_p (op_a, SET_DEST (PATTERN (prev_insn))))
1650 op_a = src;
1651 else if (rtx_equal_p (op_b, SET_DEST (PATTERN (prev_insn))))
1652 op_b = src;
1654 if (CONST_INT_P (op_a))
1656 rtx tmp = op_a;
1657 op_a = op_b;
1658 op_b = tmp;
1659 code = swap_condition (code);
1664 /* Now, look to see if we can get the right constant by
1665 adjusting the conditional. */
1666 if (CONST_INT_P (op_b))
1668 HOST_WIDE_INT desired_val = INTVAL (target);
1669 HOST_WIDE_INT actual_val = INTVAL (op_b);
1671 switch (code)
1673 case LT:
1674 if (actual_val == desired_val + 1)
1676 code = LE;
1677 op_b = GEN_INT (desired_val);
1679 break;
1680 case LE:
1681 if (actual_val == desired_val - 1)
1683 code = LT;
1684 op_b = GEN_INT (desired_val);
1686 break;
1687 case GT:
1688 if (actual_val == desired_val - 1)
1690 code = GE;
1691 op_b = GEN_INT (desired_val);
1693 break;
1694 case GE:
1695 if (actual_val == desired_val + 1)
1697 code = GT;
1698 op_b = GEN_INT (desired_val);
1700 break;
1701 default:
1702 break;
1706 /* If we made any changes, generate a new conditional that is
1707 equivalent to what we started with, but has the right
1708 constants in it. */
1709 if (code != GET_CODE (if_info->cond)
1710 || op_a != XEXP (if_info->cond, 0)
1711 || op_b != XEXP (if_info->cond, 1))
1713 cond = gen_rtx_fmt_ee (code, GET_MODE (cond), op_a, op_b);
1714 *earliest = if_info->cond_earliest;
1715 return cond;
1719 cond = canonicalize_condition (if_info->jump, cond, reverse,
1720 earliest, target, false, true);
1721 if (! cond || ! reg_mentioned_p (target, cond))
1722 return NULL;
1724 /* We almost certainly searched back to a different place.
1725 Need to re-verify correct lifetimes. */
1727 /* X may not be mentioned in the range (cond_earliest, jump]. */
1728 for (insn = if_info->jump; insn != *earliest; insn = PREV_INSN (insn))
1729 if (INSN_P (insn) && reg_overlap_mentioned_p (if_info->x, PATTERN (insn)))
1730 return NULL;
1732 /* A and B may not be modified in the range [cond_earliest, jump). */
1733 for (insn = *earliest; insn != if_info->jump; insn = NEXT_INSN (insn))
1734 if (INSN_P (insn)
1735 && (modified_in_p (if_info->a, insn)
1736 || modified_in_p (if_info->b, insn)))
1737 return NULL;
1739 return cond;
1742 /* Convert "if (a < b) x = a; else x = b;" to "x = min(a, b);", etc. */
1744 static int
1745 noce_try_minmax (struct noce_if_info *if_info)
1747 rtx cond, earliest, target, seq;
1748 enum rtx_code code, op;
1749 int unsignedp;
1751 /* ??? Reject modes with NaNs or signed zeros since we don't know how
1752 they will be resolved with an SMIN/SMAX. It wouldn't be too hard
1753 to get the target to tell us... */
1754 if (HONOR_SIGNED_ZEROS (GET_MODE (if_info->x))
1755 || HONOR_NANS (GET_MODE (if_info->x)))
1756 return FALSE;
1758 cond = noce_get_alt_condition (if_info, if_info->a, &earliest);
1759 if (!cond)
1760 return FALSE;
1762 /* Verify the condition is of the form we expect, and canonicalize
1763 the comparison code. */
1764 code = GET_CODE (cond);
1765 if (rtx_equal_p (XEXP (cond, 0), if_info->a))
1767 if (! rtx_equal_p (XEXP (cond, 1), if_info->b))
1768 return FALSE;
1770 else if (rtx_equal_p (XEXP (cond, 1), if_info->a))
1772 if (! rtx_equal_p (XEXP (cond, 0), if_info->b))
1773 return FALSE;
1774 code = swap_condition (code);
1776 else
1777 return FALSE;
1779 /* Determine what sort of operation this is. Note that the code is for
1780 a taken branch, so the code->operation mapping appears backwards. */
1781 switch (code)
1783 case LT:
1784 case LE:
1785 case UNLT:
1786 case UNLE:
1787 op = SMAX;
1788 unsignedp = 0;
1789 break;
1790 case GT:
1791 case GE:
1792 case UNGT:
1793 case UNGE:
1794 op = SMIN;
1795 unsignedp = 0;
1796 break;
1797 case LTU:
1798 case LEU:
1799 op = UMAX;
1800 unsignedp = 1;
1801 break;
1802 case GTU:
1803 case GEU:
1804 op = UMIN;
1805 unsignedp = 1;
1806 break;
1807 default:
1808 return FALSE;
1811 start_sequence ();
1813 target = expand_simple_binop (GET_MODE (if_info->x), op,
1814 if_info->a, if_info->b,
1815 if_info->x, unsignedp, OPTAB_WIDEN);
1816 if (! target)
1818 end_sequence ();
1819 return FALSE;
1821 if (target != if_info->x)
1822 noce_emit_move_insn (if_info->x, target);
1824 seq = end_ifcvt_sequence (if_info);
1825 if (!seq)
1826 return FALSE;
1828 emit_insn_before_setloc (seq, if_info->jump, INSN_LOCATOR (if_info->insn_a));
1829 if_info->cond = cond;
1830 if_info->cond_earliest = earliest;
1832 return TRUE;
1835 /* Convert "if (a < 0) x = -a; else x = a;" to "x = abs(a);",
1836 "if (a < 0) x = ~a; else x = a;" to "x = one_cmpl_abs(a);",
1837 etc. */
1839 static int
1840 noce_try_abs (struct noce_if_info *if_info)
1842 rtx cond, earliest, target, seq, a, b, c;
1843 int negate;
1844 bool one_cmpl = false;
1846 /* Reject modes with signed zeros. */
1847 if (HONOR_SIGNED_ZEROS (GET_MODE (if_info->x)))
1848 return FALSE;
1850 /* Recognize A and B as constituting an ABS or NABS. The canonical
1851 form is a branch around the negation, taken when the object is the
1852 first operand of a comparison against 0 that evaluates to true. */
1853 a = if_info->a;
1854 b = if_info->b;
1855 if (GET_CODE (a) == NEG && rtx_equal_p (XEXP (a, 0), b))
1856 negate = 0;
1857 else if (GET_CODE (b) == NEG && rtx_equal_p (XEXP (b, 0), a))
1859 c = a; a = b; b = c;
1860 negate = 1;
1862 else if (GET_CODE (a) == NOT && rtx_equal_p (XEXP (a, 0), b))
1864 negate = 0;
1865 one_cmpl = true;
1867 else if (GET_CODE (b) == NOT && rtx_equal_p (XEXP (b, 0), a))
1869 c = a; a = b; b = c;
1870 negate = 1;
1871 one_cmpl = true;
1873 else
1874 return FALSE;
1876 cond = noce_get_alt_condition (if_info, b, &earliest);
1877 if (!cond)
1878 return FALSE;
1880 /* Verify the condition is of the form we expect. */
1881 if (rtx_equal_p (XEXP (cond, 0), b))
1882 c = XEXP (cond, 1);
1883 else if (rtx_equal_p (XEXP (cond, 1), b))
1885 c = XEXP (cond, 0);
1886 negate = !negate;
1888 else
1889 return FALSE;
1891 /* Verify that C is zero. Search one step backward for a
1892 REG_EQUAL note or a simple source if necessary. */
1893 if (REG_P (c))
1895 rtx set, insn = prev_nonnote_insn (earliest);
1896 if (insn
1897 && BLOCK_FOR_INSN (insn) == BLOCK_FOR_INSN (earliest)
1898 && (set = single_set (insn))
1899 && rtx_equal_p (SET_DEST (set), c))
1901 rtx note = find_reg_equal_equiv_note (insn);
1902 if (note)
1903 c = XEXP (note, 0);
1904 else
1905 c = SET_SRC (set);
1907 else
1908 return FALSE;
1910 if (MEM_P (c)
1911 && GET_CODE (XEXP (c, 0)) == SYMBOL_REF
1912 && CONSTANT_POOL_ADDRESS_P (XEXP (c, 0)))
1913 c = get_pool_constant (XEXP (c, 0));
1915 /* Work around funny ideas get_condition has wrt canonicalization.
1916 Note that these rtx constants are known to be CONST_INT, and
1917 therefore imply integer comparisons. */
1918 if (c == constm1_rtx && GET_CODE (cond) == GT)
1920 else if (c == const1_rtx && GET_CODE (cond) == LT)
1922 else if (c != CONST0_RTX (GET_MODE (b)))
1923 return FALSE;
1925 /* Determine what sort of operation this is. */
1926 switch (GET_CODE (cond))
1928 case LT:
1929 case LE:
1930 case UNLT:
1931 case UNLE:
1932 negate = !negate;
1933 break;
1934 case GT:
1935 case GE:
1936 case UNGT:
1937 case UNGE:
1938 break;
1939 default:
1940 return FALSE;
1943 start_sequence ();
1944 if (one_cmpl)
1945 target = expand_one_cmpl_abs_nojump (GET_MODE (if_info->x), b,
1946 if_info->x);
1947 else
1948 target = expand_abs_nojump (GET_MODE (if_info->x), b, if_info->x, 1);
1950 /* ??? It's a quandary whether cmove would be better here, especially
1951 for integers. Perhaps combine will clean things up. */
1952 if (target && negate)
1954 if (one_cmpl)
1955 target = expand_simple_unop (GET_MODE (target), NOT, target,
1956 if_info->x, 0);
1957 else
1958 target = expand_simple_unop (GET_MODE (target), NEG, target,
1959 if_info->x, 0);
1962 if (! target)
1964 end_sequence ();
1965 return FALSE;
1968 if (target != if_info->x)
1969 noce_emit_move_insn (if_info->x, target);
1971 seq = end_ifcvt_sequence (if_info);
1972 if (!seq)
1973 return FALSE;
1975 emit_insn_before_setloc (seq, if_info->jump, INSN_LOCATOR (if_info->insn_a));
1976 if_info->cond = cond;
1977 if_info->cond_earliest = earliest;
1979 return TRUE;
1982 /* Convert "if (m < 0) x = b; else x = 0;" to "x = (m >> C) & b;". */
1984 static int
1985 noce_try_sign_mask (struct noce_if_info *if_info)
1987 rtx cond, t, m, c, seq;
1988 enum machine_mode mode;
1989 enum rtx_code code;
1990 bool t_unconditional;
1992 cond = if_info->cond;
1993 code = GET_CODE (cond);
1994 m = XEXP (cond, 0);
1995 c = XEXP (cond, 1);
1997 t = NULL_RTX;
1998 if (if_info->a == const0_rtx)
2000 if ((code == LT && c == const0_rtx)
2001 || (code == LE && c == constm1_rtx))
2002 t = if_info->b;
2004 else if (if_info->b == const0_rtx)
2006 if ((code == GE && c == const0_rtx)
2007 || (code == GT && c == constm1_rtx))
2008 t = if_info->a;
2011 if (! t || side_effects_p (t))
2012 return FALSE;
2014 /* We currently don't handle different modes. */
2015 mode = GET_MODE (t);
2016 if (GET_MODE (m) != mode)
2017 return FALSE;
2019 /* This is only profitable if T is unconditionally executed/evaluated in the
2020 original insn sequence or T is cheap. The former happens if B is the
2021 non-zero (T) value and if INSN_B was taken from TEST_BB, or there was no
2022 INSN_B which can happen for e.g. conditional stores to memory. For the
2023 cost computation use the block TEST_BB where the evaluation will end up
2024 after the transformation. */
2025 t_unconditional =
2026 (t == if_info->b
2027 && (if_info->insn_b == NULL_RTX
2028 || BLOCK_FOR_INSN (if_info->insn_b) == if_info->test_bb));
2029 if (!(t_unconditional
2030 || (rtx_cost (t, SET, optimize_bb_for_speed_p (if_info->test_bb))
2031 < COSTS_N_INSNS (2))))
2032 return FALSE;
2034 start_sequence ();
2035 /* Use emit_store_flag to generate "m < 0 ? -1 : 0" instead of expanding
2036 "(signed) m >> 31" directly. This benefits targets with specialized
2037 insns to obtain the signmask, but still uses ashr_optab otherwise. */
2038 m = emit_store_flag (gen_reg_rtx (mode), LT, m, const0_rtx, mode, 0, -1);
2039 t = m ? expand_binop (mode, and_optab, m, t, NULL_RTX, 0, OPTAB_DIRECT)
2040 : NULL_RTX;
2042 if (!t)
2044 end_sequence ();
2045 return FALSE;
2048 noce_emit_move_insn (if_info->x, t);
2050 seq = end_ifcvt_sequence (if_info);
2051 if (!seq)
2052 return FALSE;
2054 emit_insn_before_setloc (seq, if_info->jump, INSN_LOCATOR (if_info->insn_a));
2055 return TRUE;
2059 /* Optimize away "if (x & C) x |= C" and similar bit manipulation
2060 transformations. */
2062 static int
2063 noce_try_bitop (struct noce_if_info *if_info)
2065 rtx cond, x, a, result, seq;
2066 enum machine_mode mode;
2067 enum rtx_code code;
2068 int bitnum;
2070 x = if_info->x;
2071 cond = if_info->cond;
2072 code = GET_CODE (cond);
2074 /* Check for no else condition. */
2075 if (! rtx_equal_p (x, if_info->b))
2076 return FALSE;
2078 /* Check for a suitable condition. */
2079 if (code != NE && code != EQ)
2080 return FALSE;
2081 if (XEXP (cond, 1) != const0_rtx)
2082 return FALSE;
2083 cond = XEXP (cond, 0);
2085 /* ??? We could also handle AND here. */
2086 if (GET_CODE (cond) == ZERO_EXTRACT)
2088 if (XEXP (cond, 1) != const1_rtx
2089 || !CONST_INT_P (XEXP (cond, 2))
2090 || ! rtx_equal_p (x, XEXP (cond, 0)))
2091 return FALSE;
2092 bitnum = INTVAL (XEXP (cond, 2));
2093 mode = GET_MODE (x);
2094 if (BITS_BIG_ENDIAN)
2095 bitnum = GET_MODE_BITSIZE (mode) - 1 - bitnum;
2096 if (bitnum < 0 || bitnum >= HOST_BITS_PER_WIDE_INT)
2097 return FALSE;
2099 else
2100 return FALSE;
2102 a = if_info->a;
2103 if (GET_CODE (a) == IOR || GET_CODE (a) == XOR)
2105 /* Check for "if (X & C) x = x op C". */
2106 if (! rtx_equal_p (x, XEXP (a, 0))
2107 || !CONST_INT_P (XEXP (a, 1))
2108 || (INTVAL (XEXP (a, 1)) & GET_MODE_MASK (mode))
2109 != (unsigned HOST_WIDE_INT) 1 << bitnum)
2110 return FALSE;
2112 /* if ((x & C) == 0) x |= C; is transformed to x |= C. */
2113 /* if ((x & C) != 0) x |= C; is transformed to nothing. */
2114 if (GET_CODE (a) == IOR)
2115 result = (code == NE) ? a : NULL_RTX;
2116 else if (code == NE)
2118 /* if ((x & C) == 0) x ^= C; is transformed to x |= C. */
2119 result = gen_int_mode ((HOST_WIDE_INT) 1 << bitnum, mode);
2120 result = simplify_gen_binary (IOR, mode, x, result);
2122 else
2124 /* if ((x & C) != 0) x ^= C; is transformed to x &= ~C. */
2125 result = gen_int_mode (~((HOST_WIDE_INT) 1 << bitnum), mode);
2126 result = simplify_gen_binary (AND, mode, x, result);
2129 else if (GET_CODE (a) == AND)
2131 /* Check for "if (X & C) x &= ~C". */
2132 if (! rtx_equal_p (x, XEXP (a, 0))
2133 || !CONST_INT_P (XEXP (a, 1))
2134 || (INTVAL (XEXP (a, 1)) & GET_MODE_MASK (mode))
2135 != (~((HOST_WIDE_INT) 1 << bitnum) & GET_MODE_MASK (mode)))
2136 return FALSE;
2138 /* if ((x & C) == 0) x &= ~C; is transformed to nothing. */
2139 /* if ((x & C) != 0) x &= ~C; is transformed to x &= ~C. */
2140 result = (code == EQ) ? a : NULL_RTX;
2142 else
2143 return FALSE;
2145 if (result)
2147 start_sequence ();
2148 noce_emit_move_insn (x, result);
2149 seq = end_ifcvt_sequence (if_info);
2150 if (!seq)
2151 return FALSE;
2153 emit_insn_before_setloc (seq, if_info->jump,
2154 INSN_LOCATOR (if_info->insn_a));
2156 return TRUE;
2160 /* Similar to get_condition, only the resulting condition must be
2161 valid at JUMP, instead of at EARLIEST.
2163 If THEN_ELSE_REVERSED is true, the fallthrough does not go to the
2164 THEN block of the caller, and we have to reverse the condition. */
2166 static rtx
2167 noce_get_condition (rtx jump, rtx *earliest, bool then_else_reversed)
2169 rtx cond, set, tmp;
2170 bool reverse;
2172 if (! any_condjump_p (jump))
2173 return NULL_RTX;
2175 set = pc_set (jump);
2177 /* If this branches to JUMP_LABEL when the condition is false,
2178 reverse the condition. */
2179 reverse = (GET_CODE (XEXP (SET_SRC (set), 2)) == LABEL_REF
2180 && XEXP (XEXP (SET_SRC (set), 2), 0) == JUMP_LABEL (jump));
2182 /* We may have to reverse because the caller's if block is not canonical,
2183 i.e. the THEN block isn't the fallthrough block for the TEST block
2184 (see find_if_header). */
2185 if (then_else_reversed)
2186 reverse = !reverse;
2188 /* If the condition variable is a register and is MODE_INT, accept it. */
2190 cond = XEXP (SET_SRC (set), 0);
2191 tmp = XEXP (cond, 0);
2192 if (REG_P (tmp) && GET_MODE_CLASS (GET_MODE (tmp)) == MODE_INT)
2194 *earliest = jump;
2196 if (reverse)
2197 cond = gen_rtx_fmt_ee (reverse_condition (GET_CODE (cond)),
2198 GET_MODE (cond), tmp, XEXP (cond, 1));
2199 return cond;
2202 /* Otherwise, fall back on canonicalize_condition to do the dirty
2203 work of manipulating MODE_CC values and COMPARE rtx codes. */
2204 return canonicalize_condition (jump, cond, reverse, earliest,
2205 NULL_RTX, false, true);
2208 /* Return true if OP is ok for if-then-else processing. */
2210 static int
2211 noce_operand_ok (const_rtx op)
2213 /* We special-case memories, so handle any of them with
2214 no address side effects. */
2215 if (MEM_P (op))
2216 return ! side_effects_p (XEXP (op, 0));
2218 if (side_effects_p (op))
2219 return FALSE;
2221 return ! may_trap_p (op);
2224 /* Return true if a write into MEM may trap or fault. */
2226 static bool
2227 noce_mem_write_may_trap_or_fault_p (const_rtx mem)
2229 rtx addr;
2231 if (MEM_READONLY_P (mem))
2232 return true;
2234 if (may_trap_or_fault_p (mem))
2235 return true;
2237 addr = XEXP (mem, 0);
2239 /* Call target hook to avoid the effects of -fpic etc.... */
2240 addr = targetm.delegitimize_address (addr);
2242 while (addr)
2243 switch (GET_CODE (addr))
2245 case CONST:
2246 case PRE_DEC:
2247 case PRE_INC:
2248 case POST_DEC:
2249 case POST_INC:
2250 case POST_MODIFY:
2251 addr = XEXP (addr, 0);
2252 break;
2253 case LO_SUM:
2254 case PRE_MODIFY:
2255 addr = XEXP (addr, 1);
2256 break;
2257 case PLUS:
2258 if (CONST_INT_P (XEXP (addr, 1)))
2259 addr = XEXP (addr, 0);
2260 else
2261 return false;
2262 break;
2263 case LABEL_REF:
2264 return true;
2265 case SYMBOL_REF:
2266 if (SYMBOL_REF_DECL (addr)
2267 && decl_readonly_section (SYMBOL_REF_DECL (addr), 0))
2268 return true;
2269 return false;
2270 default:
2271 return false;
2274 return false;
2277 /* Return whether we can use store speculation for MEM. TOP_BB is the
2278 basic block above the conditional block where we are considering
2279 doing the speculative store. We look for whether MEM is set
2280 unconditionally later in the function. */
2282 static bool
2283 noce_can_store_speculate_p (basic_block top_bb, const_rtx mem)
2285 basic_block dominator;
2287 for (dominator = get_immediate_dominator (CDI_POST_DOMINATORS, top_bb);
2288 dominator != NULL;
2289 dominator = get_immediate_dominator (CDI_POST_DOMINATORS, dominator))
2291 rtx insn;
2293 FOR_BB_INSNS (dominator, insn)
2295 /* If we see something that might be a memory barrier, we
2296 have to stop looking. Even if the MEM is set later in
2297 the function, we still don't want to set it
2298 unconditionally before the barrier. */
2299 if (INSN_P (insn)
2300 && (volatile_insn_p (PATTERN (insn))
2301 || (CALL_P (insn) && (!RTL_CONST_CALL_P (insn)))))
2302 return false;
2304 if (memory_modified_in_insn_p (mem, insn))
2305 return true;
2306 if (modified_in_p (XEXP (mem, 0), insn))
2307 return false;
2312 return false;
2315 /* Given a simple IF-THEN-JOIN or IF-THEN-ELSE-JOIN block, attempt to convert
2316 it without using conditional execution. Return TRUE if we were successful
2317 at converting the block. */
2319 static int
2320 noce_process_if_block (struct noce_if_info *if_info)
2322 basic_block test_bb = if_info->test_bb; /* test block */
2323 basic_block then_bb = if_info->then_bb; /* THEN */
2324 basic_block else_bb = if_info->else_bb; /* ELSE or NULL */
2325 basic_block join_bb = if_info->join_bb; /* JOIN */
2326 rtx jump = if_info->jump;
2327 rtx cond = if_info->cond;
2328 rtx insn_a, insn_b;
2329 rtx set_a, set_b;
2330 rtx orig_x, x, a, b;
2332 /* We're looking for patterns of the form
2334 (1) if (...) x = a; else x = b;
2335 (2) x = b; if (...) x = a;
2336 (3) if (...) x = a; // as if with an initial x = x.
2338 The later patterns require jumps to be more expensive.
2340 ??? For future expansion, look for multiple X in such patterns. */
2342 /* Look for one of the potential sets. */
2343 insn_a = first_active_insn (then_bb);
2344 if (! insn_a
2345 || insn_a != last_active_insn (then_bb, FALSE)
2346 || (set_a = single_set (insn_a)) == NULL_RTX)
2347 return FALSE;
2349 x = SET_DEST (set_a);
2350 a = SET_SRC (set_a);
2352 /* Look for the other potential set. Make sure we've got equivalent
2353 destinations. */
2354 /* ??? This is overconservative. Storing to two different mems is
2355 as easy as conditionally computing the address. Storing to a
2356 single mem merely requires a scratch memory to use as one of the
2357 destination addresses; often the memory immediately below the
2358 stack pointer is available for this. */
2359 set_b = NULL_RTX;
2360 if (else_bb)
2362 insn_b = first_active_insn (else_bb);
2363 if (! insn_b
2364 || insn_b != last_active_insn (else_bb, FALSE)
2365 || (set_b = single_set (insn_b)) == NULL_RTX
2366 || ! rtx_equal_p (x, SET_DEST (set_b)))
2367 return FALSE;
2369 else
2371 insn_b = prev_nonnote_insn (if_info->cond_earliest);
2372 while (insn_b && DEBUG_INSN_P (insn_b))
2373 insn_b = prev_nonnote_insn (insn_b);
2374 /* We're going to be moving the evaluation of B down from above
2375 COND_EARLIEST to JUMP. Make sure the relevant data is still
2376 intact. */
2377 if (! insn_b
2378 || BLOCK_FOR_INSN (insn_b) != BLOCK_FOR_INSN (if_info->cond_earliest)
2379 || !NONJUMP_INSN_P (insn_b)
2380 || (set_b = single_set (insn_b)) == NULL_RTX
2381 || ! rtx_equal_p (x, SET_DEST (set_b))
2382 || ! noce_operand_ok (SET_SRC (set_b))
2383 || reg_overlap_mentioned_p (x, SET_SRC (set_b))
2384 || modified_between_p (SET_SRC (set_b), insn_b, jump)
2385 /* Likewise with X. In particular this can happen when
2386 noce_get_condition looks farther back in the instruction
2387 stream than one might expect. */
2388 || reg_overlap_mentioned_p (x, cond)
2389 || reg_overlap_mentioned_p (x, a)
2390 || modified_between_p (x, insn_b, jump))
2391 insn_b = set_b = NULL_RTX;
2394 /* If x has side effects then only the if-then-else form is safe to
2395 convert. But even in that case we would need to restore any notes
2396 (such as REG_INC) at then end. That can be tricky if
2397 noce_emit_move_insn expands to more than one insn, so disable the
2398 optimization entirely for now if there are side effects. */
2399 if (side_effects_p (x))
2400 return FALSE;
2402 b = (set_b ? SET_SRC (set_b) : x);
2404 /* Only operate on register destinations, and even then avoid extending
2405 the lifetime of hard registers on small register class machines. */
2406 orig_x = x;
2407 if (!REG_P (x)
2408 || (SMALL_REGISTER_CLASSES
2409 && REGNO (x) < FIRST_PSEUDO_REGISTER))
2411 if (GET_MODE (x) == BLKmode)
2412 return FALSE;
2414 if (GET_CODE (x) == ZERO_EXTRACT
2415 && (!CONST_INT_P (XEXP (x, 1))
2416 || !CONST_INT_P (XEXP (x, 2))))
2417 return FALSE;
2419 x = gen_reg_rtx (GET_MODE (GET_CODE (x) == STRICT_LOW_PART
2420 ? XEXP (x, 0) : x));
2423 /* Don't operate on sources that may trap or are volatile. */
2424 if (! noce_operand_ok (a) || ! noce_operand_ok (b))
2425 return FALSE;
2427 retry:
2428 /* Set up the info block for our subroutines. */
2429 if_info->insn_a = insn_a;
2430 if_info->insn_b = insn_b;
2431 if_info->x = x;
2432 if_info->a = a;
2433 if_info->b = b;
2435 /* Try optimizations in some approximation of a useful order. */
2436 /* ??? Should first look to see if X is live incoming at all. If it
2437 isn't, we don't need anything but an unconditional set. */
2439 /* Look and see if A and B are really the same. Avoid creating silly
2440 cmove constructs that no one will fix up later. */
2441 if (rtx_equal_p (a, b))
2443 /* If we have an INSN_B, we don't have to create any new rtl. Just
2444 move the instruction that we already have. If we don't have an
2445 INSN_B, that means that A == X, and we've got a noop move. In
2446 that case don't do anything and let the code below delete INSN_A. */
2447 if (insn_b && else_bb)
2449 rtx note;
2451 if (else_bb && insn_b == BB_END (else_bb))
2452 BB_END (else_bb) = PREV_INSN (insn_b);
2453 reorder_insns (insn_b, insn_b, PREV_INSN (jump));
2455 /* If there was a REG_EQUAL note, delete it since it may have been
2456 true due to this insn being after a jump. */
2457 if ((note = find_reg_note (insn_b, REG_EQUAL, NULL_RTX)) != 0)
2458 remove_note (insn_b, note);
2460 insn_b = NULL_RTX;
2462 /* If we have "x = b; if (...) x = a;", and x has side-effects, then
2463 x must be executed twice. */
2464 else if (insn_b && side_effects_p (orig_x))
2465 return FALSE;
2467 x = orig_x;
2468 goto success;
2471 if (!set_b && MEM_P (orig_x))
2473 /* Disallow the "if (...) x = a;" form (implicit "else x = x;")
2474 for optimizations if writing to x may trap or fault,
2475 i.e. it's a memory other than a static var or a stack slot,
2476 is misaligned on strict aligned machines or is read-only. If
2477 x is a read-only memory, then the program is valid only if we
2478 avoid the store into it. If there are stores on both the
2479 THEN and ELSE arms, then we can go ahead with the conversion;
2480 either the program is broken, or the condition is always
2481 false such that the other memory is selected. */
2482 if (noce_mem_write_may_trap_or_fault_p (orig_x))
2483 return FALSE;
2485 /* Avoid store speculation: given "if (...) x = a" where x is a
2486 MEM, we only want to do the store if x is always set
2487 somewhere in the function. This avoids cases like
2488 if (pthread_mutex_trylock(mutex))
2489 ++global_variable;
2490 where we only want global_variable to be changed if the mutex
2491 is held. FIXME: This should ideally be expressed directly in
2492 RTL somehow. */
2493 if (!noce_can_store_speculate_p (test_bb, orig_x))
2494 return FALSE;
2497 if (noce_try_move (if_info))
2498 goto success;
2499 if (noce_try_store_flag (if_info))
2500 goto success;
2501 if (noce_try_bitop (if_info))
2502 goto success;
2503 if (noce_try_minmax (if_info))
2504 goto success;
2505 if (noce_try_abs (if_info))
2506 goto success;
2507 if (HAVE_conditional_move
2508 && noce_try_cmove (if_info))
2509 goto success;
2510 if (! targetm.have_conditional_execution ())
2512 if (noce_try_store_flag_constants (if_info))
2513 goto success;
2514 if (noce_try_addcc (if_info))
2515 goto success;
2516 if (noce_try_store_flag_mask (if_info))
2517 goto success;
2518 if (HAVE_conditional_move
2519 && noce_try_cmove_arith (if_info))
2520 goto success;
2521 if (noce_try_sign_mask (if_info))
2522 goto success;
2525 if (!else_bb && set_b)
2527 insn_b = set_b = NULL_RTX;
2528 b = orig_x;
2529 goto retry;
2532 return FALSE;
2534 success:
2536 /* If we used a temporary, fix it up now. */
2537 if (orig_x != x)
2539 rtx seq;
2541 start_sequence ();
2542 noce_emit_move_insn (orig_x, x);
2543 seq = get_insns ();
2544 set_used_flags (orig_x);
2545 unshare_all_rtl_in_chain (seq);
2546 end_sequence ();
2548 emit_insn_before_setloc (seq, BB_END (test_bb), INSN_LOCATOR (insn_a));
2551 /* The original THEN and ELSE blocks may now be removed. The test block
2552 must now jump to the join block. If the test block and the join block
2553 can be merged, do so. */
2554 if (else_bb)
2556 delete_basic_block (else_bb);
2557 num_true_changes++;
2559 else
2560 remove_edge (find_edge (test_bb, join_bb));
2562 remove_edge (find_edge (then_bb, join_bb));
2563 redirect_edge_and_branch_force (single_succ_edge (test_bb), join_bb);
2564 delete_basic_block (then_bb);
2565 num_true_changes++;
2567 if (can_merge_blocks_p (test_bb, join_bb))
2569 merge_blocks (test_bb, join_bb);
2570 num_true_changes++;
2573 num_updated_if_blocks++;
2574 return TRUE;
2577 /* Check whether a block is suitable for conditional move conversion.
2578 Every insn must be a simple set of a register to a constant or a
2579 register. For each assignment, store the value in the array VALS,
2580 indexed by register number, then store the register number in
2581 REGS. COND is the condition we will test. */
2583 static int
2584 check_cond_move_block (basic_block bb, rtx *vals, VEC (int, heap) **regs,
2585 rtx cond)
2587 rtx insn;
2589 /* We can only handle simple jumps at the end of the basic block.
2590 It is almost impossible to update the CFG otherwise. */
2591 insn = BB_END (bb);
2592 if (JUMP_P (insn) && !onlyjump_p (insn))
2593 return FALSE;
2595 FOR_BB_INSNS (bb, insn)
2597 rtx set, dest, src;
2599 if (!NONDEBUG_INSN_P (insn) || JUMP_P (insn))
2600 continue;
2601 set = single_set (insn);
2602 if (!set)
2603 return FALSE;
2605 dest = SET_DEST (set);
2606 src = SET_SRC (set);
2607 if (!REG_P (dest)
2608 || (SMALL_REGISTER_CLASSES && HARD_REGISTER_P (dest)))
2609 return FALSE;
2611 if (!CONSTANT_P (src) && !register_operand (src, VOIDmode))
2612 return FALSE;
2614 if (side_effects_p (src) || side_effects_p (dest))
2615 return FALSE;
2617 if (may_trap_p (src) || may_trap_p (dest))
2618 return FALSE;
2620 /* Don't try to handle this if the source register was
2621 modified earlier in the block. */
2622 if ((REG_P (src)
2623 && vals[REGNO (src)] != NULL)
2624 || (GET_CODE (src) == SUBREG && REG_P (SUBREG_REG (src))
2625 && vals[REGNO (SUBREG_REG (src))] != NULL))
2626 return FALSE;
2628 /* Don't try to handle this if the destination register was
2629 modified earlier in the block. */
2630 if (vals[REGNO (dest)] != NULL)
2631 return FALSE;
2633 /* Don't try to handle this if the condition uses the
2634 destination register. */
2635 if (reg_overlap_mentioned_p (dest, cond))
2636 return FALSE;
2638 /* Don't try to handle this if the source register is modified
2639 later in the block. */
2640 if (!CONSTANT_P (src)
2641 && modified_between_p (src, insn, NEXT_INSN (BB_END (bb))))
2642 return FALSE;
2644 vals[REGNO (dest)] = src;
2646 VEC_safe_push (int, heap, *regs, REGNO (dest));
2649 return TRUE;
2652 /* Given a basic block BB suitable for conditional move conversion,
2653 a condition COND, and arrays THEN_VALS and ELSE_VALS containing the
2654 register values depending on COND, emit the insns in the block as
2655 conditional moves. If ELSE_BLOCK is true, THEN_BB was already
2656 processed. The caller has started a sequence for the conversion.
2657 Return true if successful, false if something goes wrong. */
2659 static bool
2660 cond_move_convert_if_block (struct noce_if_info *if_infop,
2661 basic_block bb, rtx cond,
2662 rtx *then_vals, rtx *else_vals,
2663 bool else_block_p)
2665 enum rtx_code code;
2666 rtx insn, cond_arg0, cond_arg1;
2668 code = GET_CODE (cond);
2669 cond_arg0 = XEXP (cond, 0);
2670 cond_arg1 = XEXP (cond, 1);
2672 FOR_BB_INSNS (bb, insn)
2674 rtx set, target, dest, t, e;
2675 unsigned int regno;
2677 /* ??? Maybe emit conditional debug insn? */
2678 if (!NONDEBUG_INSN_P (insn) || JUMP_P (insn))
2679 continue;
2680 set = single_set (insn);
2681 gcc_assert (set && REG_P (SET_DEST (set)));
2683 dest = SET_DEST (set);
2684 regno = REGNO (dest);
2686 t = then_vals[regno];
2687 e = else_vals[regno];
2689 if (else_block_p)
2691 /* If this register was set in the then block, we already
2692 handled this case there. */
2693 if (t)
2694 continue;
2695 t = dest;
2696 gcc_assert (e);
2698 else
2700 gcc_assert (t);
2701 if (!e)
2702 e = dest;
2705 target = noce_emit_cmove (if_infop, dest, code, cond_arg0, cond_arg1,
2706 t, e);
2707 if (!target)
2708 return false;
2710 if (target != dest)
2711 noce_emit_move_insn (dest, target);
2714 return true;
2717 /* Given a simple IF-THEN-JOIN or IF-THEN-ELSE-JOIN block, attempt to convert
2718 it using only conditional moves. Return TRUE if we were successful at
2719 converting the block. */
2721 static int
2722 cond_move_process_if_block (struct noce_if_info *if_info)
2724 basic_block test_bb = if_info->test_bb;
2725 basic_block then_bb = if_info->then_bb;
2726 basic_block else_bb = if_info->else_bb;
2727 basic_block join_bb = if_info->join_bb;
2728 rtx jump = if_info->jump;
2729 rtx cond = if_info->cond;
2730 rtx seq, loc_insn;
2731 int max_reg, size, c, reg;
2732 rtx *then_vals;
2733 rtx *else_vals;
2734 VEC (int, heap) *then_regs = NULL;
2735 VEC (int, heap) *else_regs = NULL;
2736 unsigned int i;
2738 /* Build a mapping for each block to the value used for each
2739 register. */
2740 max_reg = max_reg_num ();
2741 size = (max_reg + 1) * sizeof (rtx);
2742 then_vals = (rtx *) alloca (size);
2743 else_vals = (rtx *) alloca (size);
2744 memset (then_vals, 0, size);
2745 memset (else_vals, 0, size);
2747 /* Make sure the blocks are suitable. */
2748 if (!check_cond_move_block (then_bb, then_vals, &then_regs, cond)
2749 || (else_bb
2750 && !check_cond_move_block (else_bb, else_vals, &else_regs, cond)))
2752 VEC_free (int, heap, then_regs);
2753 VEC_free (int, heap, else_regs);
2754 return FALSE;
2757 /* Make sure the blocks can be used together. If the same register
2758 is set in both blocks, and is not set to a constant in both
2759 cases, then both blocks must set it to the same register. We
2760 have already verified that if it is set to a register, that the
2761 source register does not change after the assignment. Also count
2762 the number of registers set in only one of the blocks. */
2763 c = 0;
2764 for (i = 0; VEC_iterate (int, then_regs, i, reg); i++)
2766 if (!then_vals[reg] && !else_vals[reg])
2767 continue;
2769 if (!else_vals[reg])
2770 ++c;
2771 else
2773 if (!CONSTANT_P (then_vals[reg])
2774 && !CONSTANT_P (else_vals[reg])
2775 && !rtx_equal_p (then_vals[reg], else_vals[reg]))
2777 VEC_free (int, heap, then_regs);
2778 VEC_free (int, heap, else_regs);
2779 return FALSE;
2784 /* Finish off c for MAX_CONDITIONAL_EXECUTE. */
2785 for (i = 0; VEC_iterate (int, else_regs, i, reg); ++i)
2786 if (!then_vals[reg])
2787 ++c;
2789 /* Make sure it is reasonable to convert this block. What matters
2790 is the number of assignments currently made in only one of the
2791 branches, since if we convert we are going to always execute
2792 them. */
2793 if (c > MAX_CONDITIONAL_EXECUTE)
2795 VEC_free (int, heap, then_regs);
2796 VEC_free (int, heap, else_regs);
2797 return FALSE;
2800 /* Try to emit the conditional moves. First do the then block,
2801 then do anything left in the else blocks. */
2802 start_sequence ();
2803 if (!cond_move_convert_if_block (if_info, then_bb, cond,
2804 then_vals, else_vals, false)
2805 || (else_bb
2806 && !cond_move_convert_if_block (if_info, else_bb, cond,
2807 then_vals, else_vals, true)))
2809 end_sequence ();
2810 VEC_free (int, heap, then_regs);
2811 VEC_free (int, heap, else_regs);
2812 return FALSE;
2814 seq = end_ifcvt_sequence (if_info);
2815 if (!seq)
2817 VEC_free (int, heap, then_regs);
2818 VEC_free (int, heap, else_regs);
2819 return FALSE;
2822 loc_insn = first_active_insn (then_bb);
2823 if (!loc_insn)
2825 loc_insn = first_active_insn (else_bb);
2826 gcc_assert (loc_insn);
2828 emit_insn_before_setloc (seq, jump, INSN_LOCATOR (loc_insn));
2830 if (else_bb)
2832 delete_basic_block (else_bb);
2833 num_true_changes++;
2835 else
2836 remove_edge (find_edge (test_bb, join_bb));
2838 remove_edge (find_edge (then_bb, join_bb));
2839 redirect_edge_and_branch_force (single_succ_edge (test_bb), join_bb);
2840 delete_basic_block (then_bb);
2841 num_true_changes++;
2843 if (can_merge_blocks_p (test_bb, join_bb))
2845 merge_blocks (test_bb, join_bb);
2846 num_true_changes++;
2849 num_updated_if_blocks++;
2851 VEC_free (int, heap, then_regs);
2852 VEC_free (int, heap, else_regs);
2853 return TRUE;
2857 /* Determine if a given basic block heads a simple IF-THEN-JOIN or an
2858 IF-THEN-ELSE-JOIN block.
2860 If so, we'll try to convert the insns to not require the branch,
2861 using only transformations that do not require conditional execution.
2863 Return TRUE if we were successful at converting the block. */
2865 static int
2866 noce_find_if_block (basic_block test_bb, edge then_edge, edge else_edge,
2867 int pass)
2869 basic_block then_bb, else_bb, join_bb;
2870 bool then_else_reversed = false;
2871 rtx jump, cond;
2872 rtx cond_earliest;
2873 struct noce_if_info if_info;
2875 /* We only ever should get here before reload. */
2876 gcc_assert (!reload_completed);
2878 /* Recognize an IF-THEN-ELSE-JOIN block. */
2879 if (single_pred_p (then_edge->dest)
2880 && single_succ_p (then_edge->dest)
2881 && single_pred_p (else_edge->dest)
2882 && single_succ_p (else_edge->dest)
2883 && single_succ (then_edge->dest) == single_succ (else_edge->dest))
2885 then_bb = then_edge->dest;
2886 else_bb = else_edge->dest;
2887 join_bb = single_succ (then_bb);
2889 /* Recognize an IF-THEN-JOIN block. */
2890 else if (single_pred_p (then_edge->dest)
2891 && single_succ_p (then_edge->dest)
2892 && single_succ (then_edge->dest) == else_edge->dest)
2894 then_bb = then_edge->dest;
2895 else_bb = NULL_BLOCK;
2896 join_bb = else_edge->dest;
2898 /* Recognize an IF-ELSE-JOIN block. We can have those because the order
2899 of basic blocks in cfglayout mode does not matter, so the fallthrough
2900 edge can go to any basic block (and not just to bb->next_bb, like in
2901 cfgrtl mode). */
2902 else if (single_pred_p (else_edge->dest)
2903 && single_succ_p (else_edge->dest)
2904 && single_succ (else_edge->dest) == then_edge->dest)
2906 /* The noce transformations do not apply to IF-ELSE-JOIN blocks.
2907 To make this work, we have to invert the THEN and ELSE blocks
2908 and reverse the jump condition. */
2909 then_bb = else_edge->dest;
2910 else_bb = NULL_BLOCK;
2911 join_bb = single_succ (then_bb);
2912 then_else_reversed = true;
2914 else
2915 /* Not a form we can handle. */
2916 return FALSE;
2918 /* The edges of the THEN and ELSE blocks cannot have complex edges. */
2919 if (single_succ_edge (then_bb)->flags & EDGE_COMPLEX)
2920 return FALSE;
2921 if (else_bb
2922 && single_succ_edge (else_bb)->flags & EDGE_COMPLEX)
2923 return FALSE;
2925 num_possible_if_blocks++;
2927 if (dump_file)
2929 fprintf (dump_file,
2930 "\nIF-THEN%s-JOIN block found, pass %d, test %d, then %d",
2931 (else_bb) ? "-ELSE" : "",
2932 pass, test_bb->index, then_bb->index);
2934 if (else_bb)
2935 fprintf (dump_file, ", else %d", else_bb->index);
2937 fprintf (dump_file, ", join %d\n", join_bb->index);
2940 /* If the conditional jump is more than just a conditional
2941 jump, then we can not do if-conversion on this block. */
2942 jump = BB_END (test_bb);
2943 if (! onlyjump_p (jump))
2944 return FALSE;
2946 /* If this is not a standard conditional jump, we can't parse it. */
2947 cond = noce_get_condition (jump, &cond_earliest, then_else_reversed);
2948 if (!cond)
2949 return FALSE;
2951 /* We must be comparing objects whose modes imply the size. */
2952 if (GET_MODE (XEXP (cond, 0)) == BLKmode)
2953 return FALSE;
2955 /* Initialize an IF_INFO struct to pass around. */
2956 memset (&if_info, 0, sizeof if_info);
2957 if_info.test_bb = test_bb;
2958 if_info.then_bb = then_bb;
2959 if_info.else_bb = else_bb;
2960 if_info.join_bb = join_bb;
2961 if_info.cond = cond;
2962 if_info.cond_earliest = cond_earliest;
2963 if_info.jump = jump;
2964 if_info.then_else_reversed = then_else_reversed;
2965 if_info.branch_cost = BRANCH_COST (optimize_bb_for_speed_p (test_bb),
2966 predictable_edge_p (then_edge));
2968 /* Do the real work. */
2970 if (noce_process_if_block (&if_info))
2971 return TRUE;
2973 if (HAVE_conditional_move
2974 && cond_move_process_if_block (&if_info))
2975 return TRUE;
2977 return FALSE;
2981 /* Merge the blocks and mark for local life update. */
2983 static void
2984 merge_if_block (struct ce_if_block * ce_info)
2986 basic_block test_bb = ce_info->test_bb; /* last test block */
2987 basic_block then_bb = ce_info->then_bb; /* THEN */
2988 basic_block else_bb = ce_info->else_bb; /* ELSE or NULL */
2989 basic_block join_bb = ce_info->join_bb; /* join block */
2990 basic_block combo_bb;
2992 /* All block merging is done into the lower block numbers. */
2994 combo_bb = test_bb;
2995 df_set_bb_dirty (test_bb);
2997 /* Merge any basic blocks to handle && and || subtests. Each of
2998 the blocks are on the fallthru path from the predecessor block. */
2999 if (ce_info->num_multiple_test_blocks > 0)
3001 basic_block bb = test_bb;
3002 basic_block last_test_bb = ce_info->last_test_bb;
3003 basic_block fallthru = block_fallthru (bb);
3007 bb = fallthru;
3008 fallthru = block_fallthru (bb);
3009 merge_blocks (combo_bb, bb);
3010 num_true_changes++;
3012 while (bb != last_test_bb);
3015 /* Merge TEST block into THEN block. Normally the THEN block won't have a
3016 label, but it might if there were || tests. That label's count should be
3017 zero, and it normally should be removed. */
3019 if (then_bb)
3021 merge_blocks (combo_bb, then_bb);
3022 num_true_changes++;
3025 /* The ELSE block, if it existed, had a label. That label count
3026 will almost always be zero, but odd things can happen when labels
3027 get their addresses taken. */
3028 if (else_bb)
3030 merge_blocks (combo_bb, else_bb);
3031 num_true_changes++;
3034 /* If there was no join block reported, that means it was not adjacent
3035 to the others, and so we cannot merge them. */
3037 if (! join_bb)
3039 rtx last = BB_END (combo_bb);
3041 /* The outgoing edge for the current COMBO block should already
3042 be correct. Verify this. */
3043 if (EDGE_COUNT (combo_bb->succs) == 0)
3044 gcc_assert (find_reg_note (last, REG_NORETURN, NULL)
3045 || (NONJUMP_INSN_P (last)
3046 && GET_CODE (PATTERN (last)) == TRAP_IF
3047 && (TRAP_CONDITION (PATTERN (last))
3048 == const_true_rtx)));
3050 else
3051 /* There should still be something at the end of the THEN or ELSE
3052 blocks taking us to our final destination. */
3053 gcc_assert (JUMP_P (last)
3054 || (EDGE_SUCC (combo_bb, 0)->dest == EXIT_BLOCK_PTR
3055 && CALL_P (last)
3056 && SIBLING_CALL_P (last))
3057 || ((EDGE_SUCC (combo_bb, 0)->flags & EDGE_EH)
3058 && can_throw_internal (last)));
3061 /* The JOIN block may have had quite a number of other predecessors too.
3062 Since we've already merged the TEST, THEN and ELSE blocks, we should
3063 have only one remaining edge from our if-then-else diamond. If there
3064 is more than one remaining edge, it must come from elsewhere. There
3065 may be zero incoming edges if the THEN block didn't actually join
3066 back up (as with a call to a non-return function). */
3067 else if (EDGE_COUNT (join_bb->preds) < 2
3068 && join_bb != EXIT_BLOCK_PTR)
3070 /* We can merge the JOIN cleanly and update the dataflow try
3071 again on this pass.*/
3072 merge_blocks (combo_bb, join_bb);
3073 num_true_changes++;
3075 else
3077 /* We cannot merge the JOIN. */
3079 /* The outgoing edge for the current COMBO block should already
3080 be correct. Verify this. */
3081 gcc_assert (single_succ_p (combo_bb)
3082 && single_succ (combo_bb) == join_bb);
3084 /* Remove the jump and cruft from the end of the COMBO block. */
3085 if (join_bb != EXIT_BLOCK_PTR)
3086 tidy_fallthru_edge (single_succ_edge (combo_bb));
3089 num_updated_if_blocks++;
3092 /* Find a block ending in a simple IF condition and try to transform it
3093 in some way. When converting a multi-block condition, put the new code
3094 in the first such block and delete the rest. Return a pointer to this
3095 first block if some transformation was done. Return NULL otherwise. */
3097 static basic_block
3098 find_if_header (basic_block test_bb, int pass)
3100 ce_if_block_t ce_info;
3101 edge then_edge;
3102 edge else_edge;
3104 /* The kind of block we're looking for has exactly two successors. */
3105 if (EDGE_COUNT (test_bb->succs) != 2)
3106 return NULL;
3108 then_edge = EDGE_SUCC (test_bb, 0);
3109 else_edge = EDGE_SUCC (test_bb, 1);
3111 if (df_get_bb_dirty (then_edge->dest))
3112 return NULL;
3113 if (df_get_bb_dirty (else_edge->dest))
3114 return NULL;
3116 /* Neither edge should be abnormal. */
3117 if ((then_edge->flags & EDGE_COMPLEX)
3118 || (else_edge->flags & EDGE_COMPLEX))
3119 return NULL;
3121 /* Nor exit the loop. */
3122 if ((then_edge->flags & EDGE_LOOP_EXIT)
3123 || (else_edge->flags & EDGE_LOOP_EXIT))
3124 return NULL;
3126 /* The THEN edge is canonically the one that falls through. */
3127 if (then_edge->flags & EDGE_FALLTHRU)
3129 else if (else_edge->flags & EDGE_FALLTHRU)
3131 edge e = else_edge;
3132 else_edge = then_edge;
3133 then_edge = e;
3135 else
3136 /* Otherwise this must be a multiway branch of some sort. */
3137 return NULL;
3139 memset (&ce_info, 0, sizeof (ce_info));
3140 ce_info.test_bb = test_bb;
3141 ce_info.then_bb = then_edge->dest;
3142 ce_info.else_bb = else_edge->dest;
3143 ce_info.pass = pass;
3145 #ifdef IFCVT_INIT_EXTRA_FIELDS
3146 IFCVT_INIT_EXTRA_FIELDS (&ce_info);
3147 #endif
3149 if (!reload_completed
3150 && noce_find_if_block (test_bb, then_edge, else_edge, pass))
3151 goto success;
3153 if (reload_completed
3154 && targetm.have_conditional_execution ()
3155 && cond_exec_find_if_block (&ce_info))
3156 goto success;
3158 if (HAVE_trap
3159 && optab_handler (ctrap_optab, word_mode)->insn_code != CODE_FOR_nothing
3160 && find_cond_trap (test_bb, then_edge, else_edge))
3161 goto success;
3163 if (dom_info_state (CDI_POST_DOMINATORS) >= DOM_NO_FAST_QUERY
3164 && (reload_completed || !targetm.have_conditional_execution ()))
3166 if (find_if_case_1 (test_bb, then_edge, else_edge))
3167 goto success;
3168 if (find_if_case_2 (test_bb, then_edge, else_edge))
3169 goto success;
3172 return NULL;
3174 success:
3175 if (dump_file)
3176 fprintf (dump_file, "Conversion succeeded on pass %d.\n", pass);
3177 /* Set this so we continue looking. */
3178 cond_exec_changed_p = TRUE;
3179 return ce_info.test_bb;
3182 /* Return true if a block has two edges, one of which falls through to the next
3183 block, and the other jumps to a specific block, so that we can tell if the
3184 block is part of an && test or an || test. Returns either -1 or the number
3185 of non-note, non-jump, non-USE/CLOBBER insns in the block. */
3187 static int
3188 block_jumps_and_fallthru_p (basic_block cur_bb, basic_block target_bb)
3190 edge cur_edge;
3191 int fallthru_p = FALSE;
3192 int jump_p = FALSE;
3193 rtx insn;
3194 rtx end;
3195 int n_insns = 0;
3196 edge_iterator ei;
3198 if (!cur_bb || !target_bb)
3199 return -1;
3201 /* If no edges, obviously it doesn't jump or fallthru. */
3202 if (EDGE_COUNT (cur_bb->succs) == 0)
3203 return FALSE;
3205 FOR_EACH_EDGE (cur_edge, ei, cur_bb->succs)
3207 if (cur_edge->flags & EDGE_COMPLEX)
3208 /* Anything complex isn't what we want. */
3209 return -1;
3211 else if (cur_edge->flags & EDGE_FALLTHRU)
3212 fallthru_p = TRUE;
3214 else if (cur_edge->dest == target_bb)
3215 jump_p = TRUE;
3217 else
3218 return -1;
3221 if ((jump_p & fallthru_p) == 0)
3222 return -1;
3224 /* Don't allow calls in the block, since this is used to group && and ||
3225 together for conditional execution support. ??? we should support
3226 conditional execution support across calls for IA-64 some day, but
3227 for now it makes the code simpler. */
3228 end = BB_END (cur_bb);
3229 insn = BB_HEAD (cur_bb);
3231 while (insn != NULL_RTX)
3233 if (CALL_P (insn))
3234 return -1;
3236 if (INSN_P (insn)
3237 && !JUMP_P (insn)
3238 && !DEBUG_INSN_P (insn)
3239 && GET_CODE (PATTERN (insn)) != USE
3240 && GET_CODE (PATTERN (insn)) != CLOBBER)
3241 n_insns++;
3243 if (insn == end)
3244 break;
3246 insn = NEXT_INSN (insn);
3249 return n_insns;
3252 /* Determine if a given basic block heads a simple IF-THEN or IF-THEN-ELSE
3253 block. If so, we'll try to convert the insns to not require the branch.
3254 Return TRUE if we were successful at converting the block. */
3256 static int
3257 cond_exec_find_if_block (struct ce_if_block * ce_info)
3259 basic_block test_bb = ce_info->test_bb;
3260 basic_block then_bb = ce_info->then_bb;
3261 basic_block else_bb = ce_info->else_bb;
3262 basic_block join_bb = NULL_BLOCK;
3263 edge cur_edge;
3264 basic_block next;
3265 edge_iterator ei;
3267 ce_info->last_test_bb = test_bb;
3269 /* We only ever should get here after reload,
3270 and if we have conditional execution. */
3271 gcc_assert (reload_completed && targetm.have_conditional_execution ());
3273 /* Discover if any fall through predecessors of the current test basic block
3274 were && tests (which jump to the else block) or || tests (which jump to
3275 the then block). */
3276 if (single_pred_p (test_bb)
3277 && single_pred_edge (test_bb)->flags == EDGE_FALLTHRU)
3279 basic_block bb = single_pred (test_bb);
3280 basic_block target_bb;
3281 int max_insns = MAX_CONDITIONAL_EXECUTE;
3282 int n_insns;
3284 /* Determine if the preceding block is an && or || block. */
3285 if ((n_insns = block_jumps_and_fallthru_p (bb, else_bb)) >= 0)
3287 ce_info->and_and_p = TRUE;
3288 target_bb = else_bb;
3290 else if ((n_insns = block_jumps_and_fallthru_p (bb, then_bb)) >= 0)
3292 ce_info->and_and_p = FALSE;
3293 target_bb = then_bb;
3295 else
3296 target_bb = NULL_BLOCK;
3298 if (target_bb && n_insns <= max_insns)
3300 int total_insns = 0;
3301 int blocks = 0;
3303 ce_info->last_test_bb = test_bb;
3305 /* Found at least one && or || block, look for more. */
3308 ce_info->test_bb = test_bb = bb;
3309 total_insns += n_insns;
3310 blocks++;
3312 if (!single_pred_p (bb))
3313 break;
3315 bb = single_pred (bb);
3316 n_insns = block_jumps_and_fallthru_p (bb, target_bb);
3318 while (n_insns >= 0 && (total_insns + n_insns) <= max_insns);
3320 ce_info->num_multiple_test_blocks = blocks;
3321 ce_info->num_multiple_test_insns = total_insns;
3323 if (ce_info->and_and_p)
3324 ce_info->num_and_and_blocks = blocks;
3325 else
3326 ce_info->num_or_or_blocks = blocks;
3330 /* The THEN block of an IF-THEN combo must have exactly one predecessor,
3331 other than any || blocks which jump to the THEN block. */
3332 if ((EDGE_COUNT (then_bb->preds) - ce_info->num_or_or_blocks) != 1)
3333 return FALSE;
3335 /* The edges of the THEN and ELSE blocks cannot have complex edges. */
3336 FOR_EACH_EDGE (cur_edge, ei, then_bb->preds)
3338 if (cur_edge->flags & EDGE_COMPLEX)
3339 return FALSE;
3342 FOR_EACH_EDGE (cur_edge, ei, else_bb->preds)
3344 if (cur_edge->flags & EDGE_COMPLEX)
3345 return FALSE;
3348 /* The THEN block of an IF-THEN combo must have zero or one successors. */
3349 if (EDGE_COUNT (then_bb->succs) > 0
3350 && (!single_succ_p (then_bb)
3351 || (single_succ_edge (then_bb)->flags & EDGE_COMPLEX)
3352 || (epilogue_completed
3353 && tablejump_p (BB_END (then_bb), NULL, NULL))))
3354 return FALSE;
3356 /* If the THEN block has no successors, conditional execution can still
3357 make a conditional call. Don't do this unless the ELSE block has
3358 only one incoming edge -- the CFG manipulation is too ugly otherwise.
3359 Check for the last insn of the THEN block being an indirect jump, which
3360 is listed as not having any successors, but confuses the rest of the CE
3361 code processing. ??? we should fix this in the future. */
3362 if (EDGE_COUNT (then_bb->succs) == 0)
3364 if (single_pred_p (else_bb))
3366 rtx last_insn = BB_END (then_bb);
3368 while (last_insn
3369 && NOTE_P (last_insn)
3370 && last_insn != BB_HEAD (then_bb))
3371 last_insn = PREV_INSN (last_insn);
3373 if (last_insn
3374 && JUMP_P (last_insn)
3375 && ! simplejump_p (last_insn))
3376 return FALSE;
3378 join_bb = else_bb;
3379 else_bb = NULL_BLOCK;
3381 else
3382 return FALSE;
3385 /* If the THEN block's successor is the other edge out of the TEST block,
3386 then we have an IF-THEN combo without an ELSE. */
3387 else if (single_succ (then_bb) == else_bb)
3389 join_bb = else_bb;
3390 else_bb = NULL_BLOCK;
3393 /* If the THEN and ELSE block meet in a subsequent block, and the ELSE
3394 has exactly one predecessor and one successor, and the outgoing edge
3395 is not complex, then we have an IF-THEN-ELSE combo. */
3396 else if (single_succ_p (else_bb)
3397 && single_succ (then_bb) == single_succ (else_bb)
3398 && single_pred_p (else_bb)
3399 && !(single_succ_edge (else_bb)->flags & EDGE_COMPLEX)
3400 && !(epilogue_completed
3401 && tablejump_p (BB_END (else_bb), NULL, NULL)))
3402 join_bb = single_succ (else_bb);
3404 /* Otherwise it is not an IF-THEN or IF-THEN-ELSE combination. */
3405 else
3406 return FALSE;
3408 num_possible_if_blocks++;
3410 if (dump_file)
3412 fprintf (dump_file,
3413 "\nIF-THEN%s block found, pass %d, start block %d "
3414 "[insn %d], then %d [%d]",
3415 (else_bb) ? "-ELSE" : "",
3416 ce_info->pass,
3417 test_bb->index,
3418 BB_HEAD (test_bb) ? (int)INSN_UID (BB_HEAD (test_bb)) : -1,
3419 then_bb->index,
3420 BB_HEAD (then_bb) ? (int)INSN_UID (BB_HEAD (then_bb)) : -1);
3422 if (else_bb)
3423 fprintf (dump_file, ", else %d [%d]",
3424 else_bb->index,
3425 BB_HEAD (else_bb) ? (int)INSN_UID (BB_HEAD (else_bb)) : -1);
3427 fprintf (dump_file, ", join %d [%d]",
3428 join_bb->index,
3429 BB_HEAD (join_bb) ? (int)INSN_UID (BB_HEAD (join_bb)) : -1);
3431 if (ce_info->num_multiple_test_blocks > 0)
3432 fprintf (dump_file, ", %d %s block%s last test %d [%d]",
3433 ce_info->num_multiple_test_blocks,
3434 (ce_info->and_and_p) ? "&&" : "||",
3435 (ce_info->num_multiple_test_blocks == 1) ? "" : "s",
3436 ce_info->last_test_bb->index,
3437 ((BB_HEAD (ce_info->last_test_bb))
3438 ? (int)INSN_UID (BB_HEAD (ce_info->last_test_bb))
3439 : -1));
3441 fputc ('\n', dump_file);
3444 /* Make sure IF, THEN, and ELSE, blocks are adjacent. Actually, we get the
3445 first condition for free, since we've already asserted that there's a
3446 fallthru edge from IF to THEN. Likewise for the && and || blocks, since
3447 we checked the FALLTHRU flag, those are already adjacent to the last IF
3448 block. */
3449 /* ??? As an enhancement, move the ELSE block. Have to deal with
3450 BLOCK notes, if by no other means than backing out the merge if they
3451 exist. Sticky enough I don't want to think about it now. */
3452 next = then_bb;
3453 if (else_bb && (next = next->next_bb) != else_bb)
3454 return FALSE;
3455 if ((next = next->next_bb) != join_bb && join_bb != EXIT_BLOCK_PTR)
3457 if (else_bb)
3458 join_bb = NULL;
3459 else
3460 return FALSE;
3463 /* Do the real work. */
3465 ce_info->else_bb = else_bb;
3466 ce_info->join_bb = join_bb;
3468 /* If we have && and || tests, try to first handle combining the && and ||
3469 tests into the conditional code, and if that fails, go back and handle
3470 it without the && and ||, which at present handles the && case if there
3471 was no ELSE block. */
3472 if (cond_exec_process_if_block (ce_info, TRUE))
3473 return TRUE;
3475 if (ce_info->num_multiple_test_blocks)
3477 cancel_changes (0);
3479 if (cond_exec_process_if_block (ce_info, FALSE))
3480 return TRUE;
3483 return FALSE;
3486 /* Convert a branch over a trap, or a branch
3487 to a trap, into a conditional trap. */
3489 static int
3490 find_cond_trap (basic_block test_bb, edge then_edge, edge else_edge)
3492 basic_block then_bb = then_edge->dest;
3493 basic_block else_bb = else_edge->dest;
3494 basic_block other_bb, trap_bb;
3495 rtx trap, jump, cond, cond_earliest, seq;
3496 enum rtx_code code;
3498 /* Locate the block with the trap instruction. */
3499 /* ??? While we look for no successors, we really ought to allow
3500 EH successors. Need to fix merge_if_block for that to work. */
3501 if ((trap = block_has_only_trap (then_bb)) != NULL)
3502 trap_bb = then_bb, other_bb = else_bb;
3503 else if ((trap = block_has_only_trap (else_bb)) != NULL)
3504 trap_bb = else_bb, other_bb = then_bb;
3505 else
3506 return FALSE;
3508 if (dump_file)
3510 fprintf (dump_file, "\nTRAP-IF block found, start %d, trap %d\n",
3511 test_bb->index, trap_bb->index);
3514 /* If this is not a standard conditional jump, we can't parse it. */
3515 jump = BB_END (test_bb);
3516 cond = noce_get_condition (jump, &cond_earliest, false);
3517 if (! cond)
3518 return FALSE;
3520 /* If the conditional jump is more than just a conditional jump, then
3521 we can not do if-conversion on this block. */
3522 if (! onlyjump_p (jump))
3523 return FALSE;
3525 /* We must be comparing objects whose modes imply the size. */
3526 if (GET_MODE (XEXP (cond, 0)) == BLKmode)
3527 return FALSE;
3529 /* Reverse the comparison code, if necessary. */
3530 code = GET_CODE (cond);
3531 if (then_bb == trap_bb)
3533 code = reversed_comparison_code (cond, jump);
3534 if (code == UNKNOWN)
3535 return FALSE;
3538 /* Attempt to generate the conditional trap. */
3539 seq = gen_cond_trap (code, copy_rtx (XEXP (cond, 0)),
3540 copy_rtx (XEXP (cond, 1)),
3541 TRAP_CODE (PATTERN (trap)));
3542 if (seq == NULL)
3543 return FALSE;
3545 /* Emit the new insns before cond_earliest. */
3546 emit_insn_before_setloc (seq, cond_earliest, INSN_LOCATOR (trap));
3548 /* Delete the trap block if possible. */
3549 remove_edge (trap_bb == then_bb ? then_edge : else_edge);
3550 df_set_bb_dirty (test_bb);
3551 df_set_bb_dirty (then_bb);
3552 df_set_bb_dirty (else_bb);
3554 if (EDGE_COUNT (trap_bb->preds) == 0)
3556 delete_basic_block (trap_bb);
3557 num_true_changes++;
3560 /* Wire together the blocks again. */
3561 if (current_ir_type () == IR_RTL_CFGLAYOUT)
3562 single_succ_edge (test_bb)->flags |= EDGE_FALLTHRU;
3563 else
3565 rtx lab, newjump;
3567 lab = JUMP_LABEL (jump);
3568 newjump = emit_jump_insn_after (gen_jump (lab), jump);
3569 LABEL_NUSES (lab) += 1;
3570 JUMP_LABEL (newjump) = lab;
3571 emit_barrier_after (newjump);
3573 delete_insn (jump);
3575 if (can_merge_blocks_p (test_bb, other_bb))
3577 merge_blocks (test_bb, other_bb);
3578 num_true_changes++;
3581 num_updated_if_blocks++;
3582 return TRUE;
3585 /* Subroutine of find_cond_trap: if BB contains only a trap insn,
3586 return it. */
3588 static rtx
3589 block_has_only_trap (basic_block bb)
3591 rtx trap;
3593 /* We're not the exit block. */
3594 if (bb == EXIT_BLOCK_PTR)
3595 return NULL_RTX;
3597 /* The block must have no successors. */
3598 if (EDGE_COUNT (bb->succs) > 0)
3599 return NULL_RTX;
3601 /* The only instruction in the THEN block must be the trap. */
3602 trap = first_active_insn (bb);
3603 if (! (trap == BB_END (bb)
3604 && GET_CODE (PATTERN (trap)) == TRAP_IF
3605 && TRAP_CONDITION (PATTERN (trap)) == const_true_rtx))
3606 return NULL_RTX;
3608 return trap;
3611 /* Look for IF-THEN-ELSE cases in which one of THEN or ELSE is
3612 transformable, but not necessarily the other. There need be no
3613 JOIN block.
3615 Return TRUE if we were successful at converting the block.
3617 Cases we'd like to look at:
3620 if (test) goto over; // x not live
3621 x = a;
3622 goto label;
3623 over:
3625 becomes
3627 x = a;
3628 if (! test) goto label;
3631 if (test) goto E; // x not live
3632 x = big();
3633 goto L;
3635 x = b;
3636 goto M;
3638 becomes
3640 x = b;
3641 if (test) goto M;
3642 x = big();
3643 goto L;
3645 (3) // This one's really only interesting for targets that can do
3646 // multiway branching, e.g. IA-64 BBB bundles. For other targets
3647 // it results in multiple branches on a cache line, which often
3648 // does not sit well with predictors.
3650 if (test1) goto E; // predicted not taken
3651 x = a;
3652 if (test2) goto F;
3655 x = b;
3658 becomes
3660 x = a;
3661 if (test1) goto E;
3662 if (test2) goto F;
3664 Notes:
3666 (A) Don't do (2) if the branch is predicted against the block we're
3667 eliminating. Do it anyway if we can eliminate a branch; this requires
3668 that the sole successor of the eliminated block postdominate the other
3669 side of the if.
3671 (B) With CE, on (3) we can steal from both sides of the if, creating
3673 if (test1) x = a;
3674 if (!test1) x = b;
3675 if (test1) goto J;
3676 if (test2) goto F;
3680 Again, this is most useful if J postdominates.
3682 (C) CE substitutes for helpful life information.
3684 (D) These heuristics need a lot of work. */
3686 /* Tests for case 1 above. */
3688 static int
3689 find_if_case_1 (basic_block test_bb, edge then_edge, edge else_edge)
3691 basic_block then_bb = then_edge->dest;
3692 basic_block else_bb = else_edge->dest;
3693 basic_block new_bb;
3694 int then_bb_index;
3696 /* If we are partitioning hot/cold basic blocks, we don't want to
3697 mess up unconditional or indirect jumps that cross between hot
3698 and cold sections.
3700 Basic block partitioning may result in some jumps that appear to
3701 be optimizable (or blocks that appear to be mergeable), but which really
3702 must be left untouched (they are required to make it safely across
3703 partition boundaries). See the comments at the top of
3704 bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */
3706 if ((BB_END (then_bb)
3707 && find_reg_note (BB_END (then_bb), REG_CROSSING_JUMP, NULL_RTX))
3708 || (BB_END (test_bb)
3709 && find_reg_note (BB_END (test_bb), REG_CROSSING_JUMP, NULL_RTX))
3710 || (BB_END (else_bb)
3711 && find_reg_note (BB_END (else_bb), REG_CROSSING_JUMP,
3712 NULL_RTX)))
3713 return FALSE;
3715 /* THEN has one successor. */
3716 if (!single_succ_p (then_bb))
3717 return FALSE;
3719 /* THEN does not fall through, but is not strange either. */
3720 if (single_succ_edge (then_bb)->flags & (EDGE_COMPLEX | EDGE_FALLTHRU))
3721 return FALSE;
3723 /* THEN has one predecessor. */
3724 if (!single_pred_p (then_bb))
3725 return FALSE;
3727 /* THEN must do something. */
3728 if (forwarder_block_p (then_bb))
3729 return FALSE;
3731 num_possible_if_blocks++;
3732 if (dump_file)
3733 fprintf (dump_file,
3734 "\nIF-CASE-1 found, start %d, then %d\n",
3735 test_bb->index, then_bb->index);
3737 /* THEN is small. */
3738 if (! cheap_bb_rtx_cost_p (then_bb,
3739 COSTS_N_INSNS (BRANCH_COST (optimize_bb_for_speed_p (then_edge->src),
3740 predictable_edge_p (then_edge)))))
3741 return FALSE;
3743 /* Registers set are dead, or are predicable. */
3744 if (! dead_or_predicable (test_bb, then_bb, else_bb,
3745 single_succ (then_bb), 1))
3746 return FALSE;
3748 /* Conversion went ok, including moving the insns and fixing up the
3749 jump. Adjust the CFG to match. */
3751 /* We can avoid creating a new basic block if then_bb is immediately
3752 followed by else_bb, i.e. deleting then_bb allows test_bb to fall
3753 thru to else_bb. */
3755 if (then_bb->next_bb == else_bb
3756 && then_bb->prev_bb == test_bb
3757 && else_bb != EXIT_BLOCK_PTR)
3759 redirect_edge_succ (FALLTHRU_EDGE (test_bb), else_bb);
3760 new_bb = 0;
3762 else
3763 new_bb = redirect_edge_and_branch_force (FALLTHRU_EDGE (test_bb),
3764 else_bb);
3766 df_set_bb_dirty (test_bb);
3767 df_set_bb_dirty (else_bb);
3769 then_bb_index = then_bb->index;
3770 delete_basic_block (then_bb);
3772 /* Make rest of code believe that the newly created block is the THEN_BB
3773 block we removed. */
3774 if (new_bb)
3776 df_bb_replace (then_bb_index, new_bb);
3777 /* Since the fallthru edge was redirected from test_bb to new_bb,
3778 we need to ensure that new_bb is in the same partition as
3779 test bb (you can not fall through across section boundaries). */
3780 BB_COPY_PARTITION (new_bb, test_bb);
3783 num_true_changes++;
3784 num_updated_if_blocks++;
3786 return TRUE;
3789 /* Test for case 2 above. */
3791 static int
3792 find_if_case_2 (basic_block test_bb, edge then_edge, edge else_edge)
3794 basic_block then_bb = then_edge->dest;
3795 basic_block else_bb = else_edge->dest;
3796 edge else_succ;
3797 rtx note;
3799 /* If we are partitioning hot/cold basic blocks, we don't want to
3800 mess up unconditional or indirect jumps that cross between hot
3801 and cold sections.
3803 Basic block partitioning may result in some jumps that appear to
3804 be optimizable (or blocks that appear to be mergeable), but which really
3805 must be left untouched (they are required to make it safely across
3806 partition boundaries). See the comments at the top of
3807 bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */
3809 if ((BB_END (then_bb)
3810 && find_reg_note (BB_END (then_bb), REG_CROSSING_JUMP, NULL_RTX))
3811 || (BB_END (test_bb)
3812 && find_reg_note (BB_END (test_bb), REG_CROSSING_JUMP, NULL_RTX))
3813 || (BB_END (else_bb)
3814 && find_reg_note (BB_END (else_bb), REG_CROSSING_JUMP,
3815 NULL_RTX)))
3816 return FALSE;
3818 /* ELSE has one successor. */
3819 if (!single_succ_p (else_bb))
3820 return FALSE;
3821 else
3822 else_succ = single_succ_edge (else_bb);
3824 /* ELSE outgoing edge is not complex. */
3825 if (else_succ->flags & EDGE_COMPLEX)
3826 return FALSE;
3828 /* ELSE has one predecessor. */
3829 if (!single_pred_p (else_bb))
3830 return FALSE;
3832 /* THEN is not EXIT. */
3833 if (then_bb->index < NUM_FIXED_BLOCKS)
3834 return FALSE;
3836 /* ELSE is predicted or SUCC(ELSE) postdominates THEN. */
3837 note = find_reg_note (BB_END (test_bb), REG_BR_PROB, NULL_RTX);
3838 if (note && INTVAL (XEXP (note, 0)) >= REG_BR_PROB_BASE / 2)
3840 else if (else_succ->dest->index < NUM_FIXED_BLOCKS
3841 || dominated_by_p (CDI_POST_DOMINATORS, then_bb,
3842 else_succ->dest))
3844 else
3845 return FALSE;
3847 num_possible_if_blocks++;
3848 if (dump_file)
3849 fprintf (dump_file,
3850 "\nIF-CASE-2 found, start %d, else %d\n",
3851 test_bb->index, else_bb->index);
3853 /* ELSE is small. */
3854 if (! cheap_bb_rtx_cost_p (else_bb,
3855 COSTS_N_INSNS (BRANCH_COST (optimize_bb_for_speed_p (else_edge->src),
3856 predictable_edge_p (else_edge)))))
3857 return FALSE;
3859 /* Registers set are dead, or are predicable. */
3860 if (! dead_or_predicable (test_bb, else_bb, then_bb, else_succ->dest, 0))
3861 return FALSE;
3863 /* Conversion went ok, including moving the insns and fixing up the
3864 jump. Adjust the CFG to match. */
3866 df_set_bb_dirty (test_bb);
3867 df_set_bb_dirty (then_bb);
3868 delete_basic_block (else_bb);
3870 num_true_changes++;
3871 num_updated_if_blocks++;
3873 /* ??? We may now fallthru from one of THEN's successors into a join
3874 block. Rerun cleanup_cfg? Examine things manually? Wait? */
3876 return TRUE;
3879 /* A subroutine of dead_or_predicable called through for_each_rtx.
3880 Return 1 if a memory is found. */
3882 static int
3883 find_memory (rtx *px, void *data ATTRIBUTE_UNUSED)
3885 return MEM_P (*px);
3888 /* Used by the code above to perform the actual rtl transformations.
3889 Return TRUE if successful.
3891 TEST_BB is the block containing the conditional branch. MERGE_BB
3892 is the block containing the code to manipulate. NEW_DEST is the
3893 label TEST_BB should be branching to after the conversion.
3894 REVERSEP is true if the sense of the branch should be reversed. */
3896 static int
3897 dead_or_predicable (basic_block test_bb, basic_block merge_bb,
3898 basic_block other_bb, basic_block new_dest, int reversep)
3900 rtx head, end, jump, earliest = NULL_RTX, old_dest, new_label = NULL_RTX;
3901 /* Number of pending changes. */
3902 int n_validated_changes = 0;
3904 jump = BB_END (test_bb);
3906 /* Find the extent of the real code in the merge block. */
3907 head = BB_HEAD (merge_bb);
3908 end = BB_END (merge_bb);
3910 while (DEBUG_INSN_P (end) && end != head)
3911 end = PREV_INSN (end);
3913 /* If merge_bb ends with a tablejump, predicating/moving insn's
3914 into test_bb and then deleting merge_bb will result in the jumptable
3915 that follows merge_bb being removed along with merge_bb and then we
3916 get an unresolved reference to the jumptable. */
3917 if (tablejump_p (end, NULL, NULL))
3918 return FALSE;
3920 if (LABEL_P (head))
3921 head = NEXT_INSN (head);
3922 while (DEBUG_INSN_P (head) && head != end)
3923 head = NEXT_INSN (head);
3924 if (NOTE_P (head))
3926 if (head == end)
3928 head = end = NULL_RTX;
3929 goto no_body;
3931 head = NEXT_INSN (head);
3932 while (DEBUG_INSN_P (head) && head != end)
3933 head = NEXT_INSN (head);
3936 if (JUMP_P (end))
3938 if (head == end)
3940 head = end = NULL_RTX;
3941 goto no_body;
3943 end = PREV_INSN (end);
3944 while (DEBUG_INSN_P (end) && end != head)
3945 end = PREV_INSN (end);
3948 /* Disable handling dead code by conditional execution if the machine needs
3949 to do anything funny with the tests, etc. */
3950 #ifndef IFCVT_MODIFY_TESTS
3951 if (targetm.have_conditional_execution ())
3953 /* In the conditional execution case, we have things easy. We know
3954 the condition is reversible. We don't have to check life info
3955 because we're going to conditionally execute the code anyway.
3956 All that's left is making sure the insns involved can actually
3957 be predicated. */
3959 rtx cond, prob_val;
3961 cond = cond_exec_get_condition (jump);
3962 if (! cond)
3963 return FALSE;
3965 prob_val = find_reg_note (jump, REG_BR_PROB, NULL_RTX);
3966 if (prob_val)
3967 prob_val = XEXP (prob_val, 0);
3969 if (reversep)
3971 enum rtx_code rev = reversed_comparison_code (cond, jump);
3972 if (rev == UNKNOWN)
3973 return FALSE;
3974 cond = gen_rtx_fmt_ee (rev, GET_MODE (cond), XEXP (cond, 0),
3975 XEXP (cond, 1));
3976 if (prob_val)
3977 prob_val = GEN_INT (REG_BR_PROB_BASE - INTVAL (prob_val));
3980 if (cond_exec_process_insns (NULL, head, end, cond, prob_val, 0)
3981 && verify_changes (0))
3982 n_validated_changes = num_validated_changes ();
3983 else
3984 cancel_changes (0);
3986 earliest = jump;
3988 #endif
3989 /* Try the NCE path if the CE path did not result in any changes. */
3990 if (n_validated_changes == 0)
3992 /* In the non-conditional execution case, we have to verify that there
3993 are no trapping operations, no calls, no references to memory, and
3994 that any registers modified are dead at the branch site. */
3996 rtx insn, cond, prev;
3997 bitmap merge_set, merge_set_noclobber, test_live, test_set;
3998 unsigned i, fail = 0;
3999 bitmap_iterator bi;
4001 /* Check for no calls or trapping operations. */
4002 for (insn = head; ; insn = NEXT_INSN (insn))
4004 if (CALL_P (insn))
4005 return FALSE;
4006 if (NONDEBUG_INSN_P (insn))
4008 if (may_trap_p (PATTERN (insn)))
4009 return FALSE;
4011 /* ??? Even non-trapping memories such as stack frame
4012 references must be avoided. For stores, we collect
4013 no lifetime info; for reads, we'd have to assert
4014 true_dependence false against every store in the
4015 TEST range. */
4016 if (for_each_rtx (&PATTERN (insn), find_memory, NULL))
4017 return FALSE;
4019 if (insn == end)
4020 break;
4023 if (! any_condjump_p (jump))
4024 return FALSE;
4026 /* Find the extent of the conditional. */
4027 cond = noce_get_condition (jump, &earliest, false);
4028 if (! cond)
4029 return FALSE;
4031 /* Collect:
4032 MERGE_SET = set of registers set in MERGE_BB
4033 MERGE_SET_NOCLOBBER = like MERGE_SET, but only includes registers
4034 that are really set, not just clobbered.
4035 TEST_LIVE = set of registers live at EARLIEST
4036 TEST_SET = set of registers set between EARLIEST and the
4037 end of the block. */
4039 merge_set = BITMAP_ALLOC (&reg_obstack);
4040 merge_set_noclobber = BITMAP_ALLOC (&reg_obstack);
4041 test_live = BITMAP_ALLOC (&reg_obstack);
4042 test_set = BITMAP_ALLOC (&reg_obstack);
4044 /* ??? bb->local_set is only valid during calculate_global_regs_live,
4045 so we must recompute usage for MERGE_BB. Not so bad, I suppose,
4046 since we've already asserted that MERGE_BB is small. */
4047 /* If we allocated new pseudos (e.g. in the conditional move
4048 expander called from noce_emit_cmove), we must resize the
4049 array first. */
4050 if (max_regno < max_reg_num ())
4051 max_regno = max_reg_num ();
4053 FOR_BB_INSNS (merge_bb, insn)
4055 if (NONDEBUG_INSN_P (insn))
4057 df_simulate_find_defs (insn, merge_set);
4058 df_simulate_find_noclobber_defs (insn, merge_set_noclobber);
4062 /* For small register class machines, don't lengthen lifetimes of
4063 hard registers before reload. */
4064 if (SMALL_REGISTER_CLASSES && ! reload_completed)
4066 EXECUTE_IF_SET_IN_BITMAP (merge_set_noclobber, 0, i, bi)
4068 if (i < FIRST_PSEUDO_REGISTER
4069 && ! fixed_regs[i]
4070 && ! global_regs[i])
4071 fail = 1;
4075 /* For TEST, we're interested in a range of insns, not a whole block.
4076 Moreover, we're interested in the insns live from OTHER_BB. */
4078 /* The loop below takes the set of live registers
4079 after JUMP, and calculates the live set before EARLIEST. */
4080 bitmap_copy (test_live, df_get_live_in (other_bb));
4081 df_simulate_initialize_backwards (test_bb, test_live);
4082 for (insn = jump; ; insn = prev)
4084 if (INSN_P (insn))
4086 df_simulate_find_noclobber_defs (insn, test_set);
4087 df_simulate_one_insn_backwards (test_bb, insn, test_live);
4089 prev = PREV_INSN (insn);
4090 if (insn == earliest)
4091 break;
4094 /* We can perform the transformation if
4095 MERGE_SET_NOCLOBBER & TEST_SET
4097 MERGE_SET & TEST_LIVE)
4099 TEST_SET & DF_LIVE_IN (merge_bb)
4100 are empty. */
4102 if (bitmap_intersect_p (test_set, merge_set_noclobber)
4103 || bitmap_intersect_p (test_live, merge_set)
4104 || bitmap_intersect_p (test_set, df_get_live_in (merge_bb)))
4105 fail = 1;
4107 BITMAP_FREE (merge_set_noclobber);
4108 BITMAP_FREE (merge_set);
4109 BITMAP_FREE (test_live);
4110 BITMAP_FREE (test_set);
4112 if (fail)
4113 return FALSE;
4116 no_body:
4117 /* We don't want to use normal invert_jump or redirect_jump because
4118 we don't want to delete_insn called. Also, we want to do our own
4119 change group management. */
4121 old_dest = JUMP_LABEL (jump);
4122 if (other_bb != new_dest)
4124 new_label = block_label (new_dest);
4125 if (reversep
4126 ? ! invert_jump_1 (jump, new_label)
4127 : ! redirect_jump_1 (jump, new_label))
4128 goto cancel;
4131 if (verify_changes (n_validated_changes))
4132 confirm_change_group ();
4133 else
4134 goto cancel;
4136 if (other_bb != new_dest)
4138 redirect_jump_2 (jump, old_dest, new_label, 0, reversep);
4140 redirect_edge_succ (BRANCH_EDGE (test_bb), new_dest);
4141 if (reversep)
4143 gcov_type count, probability;
4144 count = BRANCH_EDGE (test_bb)->count;
4145 BRANCH_EDGE (test_bb)->count = FALLTHRU_EDGE (test_bb)->count;
4146 FALLTHRU_EDGE (test_bb)->count = count;
4147 probability = BRANCH_EDGE (test_bb)->probability;
4148 BRANCH_EDGE (test_bb)->probability
4149 = FALLTHRU_EDGE (test_bb)->probability;
4150 FALLTHRU_EDGE (test_bb)->probability = probability;
4151 update_br_prob_note (test_bb);
4155 /* Move the insns out of MERGE_BB to before the branch. */
4156 if (head != NULL)
4158 rtx insn;
4160 if (end == BB_END (merge_bb))
4161 BB_END (merge_bb) = PREV_INSN (head);
4163 /* PR 21767: When moving insns above a conditional branch, REG_EQUAL
4164 notes might become invalid. */
4165 insn = head;
4168 rtx note, set;
4170 if (! INSN_P (insn))
4171 continue;
4172 note = find_reg_note (insn, REG_EQUAL, NULL_RTX);
4173 if (! note)
4174 continue;
4175 set = single_set (insn);
4176 if (!set || !function_invariant_p (SET_SRC (set))
4177 || !function_invariant_p (XEXP (note, 0)))
4178 remove_note (insn, note);
4179 } while (insn != end && (insn = NEXT_INSN (insn)));
4181 reorder_insns (head, end, PREV_INSN (earliest));
4184 /* Remove the jump and edge if we can. */
4185 if (other_bb == new_dest)
4187 delete_insn (jump);
4188 remove_edge (BRANCH_EDGE (test_bb));
4189 /* ??? Can't merge blocks here, as then_bb is still in use.
4190 At minimum, the merge will get done just before bb-reorder. */
4193 return TRUE;
4195 cancel:
4196 cancel_changes (0);
4197 return FALSE;
4200 /* Main entry point for all if-conversion. */
4202 static void
4203 if_convert (void)
4205 basic_block bb;
4206 int pass;
4208 if (optimize == 1)
4210 df_live_add_problem ();
4211 df_live_set_all_dirty ();
4214 num_possible_if_blocks = 0;
4215 num_updated_if_blocks = 0;
4216 num_true_changes = 0;
4218 loop_optimizer_init (AVOID_CFG_MODIFICATIONS);
4219 mark_loop_exit_edges ();
4220 loop_optimizer_finalize ();
4221 free_dominance_info (CDI_DOMINATORS);
4223 /* Compute postdominators. */
4224 calculate_dominance_info (CDI_POST_DOMINATORS);
4226 df_set_flags (DF_LR_RUN_DCE);
4228 /* Go through each of the basic blocks looking for things to convert. If we
4229 have conditional execution, we make multiple passes to allow us to handle
4230 IF-THEN{-ELSE} blocks within other IF-THEN{-ELSE} blocks. */
4231 pass = 0;
4234 df_analyze ();
4235 /* Only need to do dce on the first pass. */
4236 df_clear_flags (DF_LR_RUN_DCE);
4237 cond_exec_changed_p = FALSE;
4238 pass++;
4240 #ifdef IFCVT_MULTIPLE_DUMPS
4241 if (dump_file && pass > 1)
4242 fprintf (dump_file, "\n\n========== Pass %d ==========\n", pass);
4243 #endif
4245 FOR_EACH_BB (bb)
4247 basic_block new_bb;
4248 while (!df_get_bb_dirty (bb)
4249 && (new_bb = find_if_header (bb, pass)) != NULL)
4250 bb = new_bb;
4253 #ifdef IFCVT_MULTIPLE_DUMPS
4254 if (dump_file && cond_exec_changed_p)
4256 if (dump_flags & TDF_SLIM)
4257 print_rtl_slim_with_bb (dump_file, get_insns (), dump_flags);
4258 else
4259 print_rtl_with_bb (dump_file, get_insns ());
4261 #endif
4263 while (cond_exec_changed_p);
4265 #ifdef IFCVT_MULTIPLE_DUMPS
4266 if (dump_file)
4267 fprintf (dump_file, "\n\n========== no more changes\n");
4268 #endif
4270 free_dominance_info (CDI_POST_DOMINATORS);
4272 if (dump_file)
4273 fflush (dump_file);
4275 clear_aux_for_blocks ();
4277 /* If we allocated new pseudos, we must resize the array for sched1. */
4278 if (max_regno < max_reg_num ())
4279 max_regno = max_reg_num ();
4281 /* Write the final stats. */
4282 if (dump_file && num_possible_if_blocks > 0)
4284 fprintf (dump_file,
4285 "\n%d possible IF blocks searched.\n",
4286 num_possible_if_blocks);
4287 fprintf (dump_file,
4288 "%d IF blocks converted.\n",
4289 num_updated_if_blocks);
4290 fprintf (dump_file,
4291 "%d true changes made.\n\n\n",
4292 num_true_changes);
4295 if (optimize == 1)
4296 df_remove_problem (df_live);
4298 #ifdef ENABLE_CHECKING
4299 verify_flow_info ();
4300 #endif
4303 static bool
4304 gate_handle_if_conversion (void)
4306 return (optimize > 0)
4307 && dbg_cnt (if_conversion);
4310 /* If-conversion and CFG cleanup. */
4311 static unsigned int
4312 rest_of_handle_if_conversion (void)
4314 if (flag_if_conversion)
4316 if (dump_file)
4317 dump_flow_info (dump_file, dump_flags);
4318 cleanup_cfg (CLEANUP_EXPENSIVE);
4319 if_convert ();
4322 cleanup_cfg (0);
4323 return 0;
4326 struct rtl_opt_pass pass_rtl_ifcvt =
4329 RTL_PASS,
4330 "ce1", /* name */
4331 gate_handle_if_conversion, /* gate */
4332 rest_of_handle_if_conversion, /* execute */
4333 NULL, /* sub */
4334 NULL, /* next */
4335 0, /* static_pass_number */
4336 TV_IFCVT, /* tv_id */
4337 0, /* properties_required */
4338 0, /* properties_provided */
4339 0, /* properties_destroyed */
4340 0, /* todo_flags_start */
4341 TODO_df_finish | TODO_verify_rtl_sharing |
4342 TODO_dump_func /* todo_flags_finish */
4346 static bool
4347 gate_handle_if_after_combine (void)
4349 return optimize > 0 && flag_if_conversion
4350 && dbg_cnt (if_after_combine);
4354 /* Rerun if-conversion, as combine may have simplified things enough
4355 to now meet sequence length restrictions. */
4356 static unsigned int
4357 rest_of_handle_if_after_combine (void)
4359 if_convert ();
4360 return 0;
4363 struct rtl_opt_pass pass_if_after_combine =
4366 RTL_PASS,
4367 "ce2", /* name */
4368 gate_handle_if_after_combine, /* gate */
4369 rest_of_handle_if_after_combine, /* execute */
4370 NULL, /* sub */
4371 NULL, /* next */
4372 0, /* static_pass_number */
4373 TV_IFCVT, /* tv_id */
4374 0, /* properties_required */
4375 0, /* properties_provided */
4376 0, /* properties_destroyed */
4377 0, /* todo_flags_start */
4378 TODO_df_finish | TODO_verify_rtl_sharing |
4379 TODO_dump_func |
4380 TODO_ggc_collect /* todo_flags_finish */
4385 static bool
4386 gate_handle_if_after_reload (void)
4388 return optimize > 0 && flag_if_conversion2
4389 && dbg_cnt (if_after_reload);
4392 static unsigned int
4393 rest_of_handle_if_after_reload (void)
4395 if_convert ();
4396 return 0;
4400 struct rtl_opt_pass pass_if_after_reload =
4403 RTL_PASS,
4404 "ce3", /* name */
4405 gate_handle_if_after_reload, /* gate */
4406 rest_of_handle_if_after_reload, /* execute */
4407 NULL, /* sub */
4408 NULL, /* next */
4409 0, /* static_pass_number */
4410 TV_IFCVT2, /* tv_id */
4411 0, /* properties_required */
4412 0, /* properties_provided */
4413 0, /* properties_destroyed */
4414 0, /* todo_flags_start */
4415 TODO_df_finish | TODO_verify_rtl_sharing |
4416 TODO_dump_func |
4417 TODO_ggc_collect /* todo_flags_finish */