* tree.c (find_tree_t, find_tree): Remove.
[official-gcc.git] / gcc / ifcvt.c
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1 /* If-conversion support.
2 Copyright (C) 2000, 2001, 2002, 2003, 2004, 2005
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 2, 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 COPYING. If not, write to the Free
19 Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA
20 02110-1301, USA. */
22 #include "config.h"
23 #include "system.h"
24 #include "coretypes.h"
25 #include "tm.h"
27 #include "rtl.h"
28 #include "regs.h"
29 #include "function.h"
30 #include "flags.h"
31 #include "insn-config.h"
32 #include "recog.h"
33 #include "except.h"
34 #include "hard-reg-set.h"
35 #include "basic-block.h"
36 #include "expr.h"
37 #include "real.h"
38 #include "output.h"
39 #include "optabs.h"
40 #include "toplev.h"
41 #include "tm_p.h"
42 #include "cfgloop.h"
43 #include "target.h"
44 #include "timevar.h"
45 #include "tree-pass.h"
48 #ifndef HAVE_conditional_execution
49 #define HAVE_conditional_execution 0
50 #endif
51 #ifndef HAVE_conditional_move
52 #define HAVE_conditional_move 0
53 #endif
54 #ifndef HAVE_incscc
55 #define HAVE_incscc 0
56 #endif
57 #ifndef HAVE_decscc
58 #define HAVE_decscc 0
59 #endif
60 #ifndef HAVE_trap
61 #define HAVE_trap 0
62 #endif
63 #ifndef HAVE_conditional_trap
64 #define HAVE_conditional_trap 0
65 #endif
67 #ifndef MAX_CONDITIONAL_EXECUTE
68 #define MAX_CONDITIONAL_EXECUTE (BRANCH_COST + 1)
69 #endif
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 which require life information to be updated. */
81 static int num_true_changes;
83 /* Whether conditional execution changes were made. */
84 static int cond_exec_changed_p;
86 /* True if life data ok at present. */
87 static bool life_data_ok;
89 /* Forward references. */
90 static int count_bb_insns (basic_block);
91 static bool cheap_bb_rtx_cost_p (basic_block, int);
92 static rtx first_active_insn (basic_block);
93 static rtx last_active_insn (basic_block, int);
94 static basic_block block_fallthru (basic_block);
95 static int cond_exec_process_insns (ce_if_block_t *, rtx, rtx, rtx, rtx, int);
96 static rtx cond_exec_get_condition (rtx);
97 static int cond_exec_process_if_block (ce_if_block_t *, int);
98 static rtx noce_get_condition (rtx, rtx *);
99 static int noce_operand_ok (rtx);
100 static int noce_process_if_block (ce_if_block_t *);
101 static int process_if_block (ce_if_block_t *);
102 static void merge_if_block (ce_if_block_t *);
103 static int find_cond_trap (basic_block, edge, edge);
104 static basic_block find_if_header (basic_block, int);
105 static int block_jumps_and_fallthru_p (basic_block, basic_block);
106 static int find_if_block (ce_if_block_t *);
107 static int find_if_case_1 (basic_block, edge, edge);
108 static int find_if_case_2 (basic_block, edge, edge);
109 static int find_memory (rtx *, void *);
110 static int dead_or_predicable (basic_block, basic_block, basic_block,
111 basic_block, int);
112 static void noce_emit_move_insn (rtx, rtx);
113 static rtx block_has_only_trap (basic_block);
115 /* Count the number of non-jump active insns in BB. */
117 static int
118 count_bb_insns (basic_block bb)
120 int count = 0;
121 rtx insn = BB_HEAD (bb);
123 while (1)
125 if (CALL_P (insn) || NONJUMP_INSN_P (insn))
126 count++;
128 if (insn == BB_END (bb))
129 break;
130 insn = NEXT_INSN (insn);
133 return count;
136 /* Determine whether the total insn_rtx_cost on non-jump insns in
137 basic block BB is less than MAX_COST. This function returns
138 false if the cost of any instruction could not be estimated. */
140 static bool
141 cheap_bb_rtx_cost_p (basic_block bb, int max_cost)
143 int count = 0;
144 rtx insn = BB_HEAD (bb);
146 while (1)
148 if (NONJUMP_INSN_P (insn))
150 int cost = insn_rtx_cost (PATTERN (insn));
151 if (cost == 0)
152 return false;
154 /* If this instruction is the load or set of a "stack" register,
155 such as a floating point register on x87, then the cost of
156 speculatively executing this instruction needs to include
157 the additional cost of popping this register off of the
158 register stack. */
159 #ifdef STACK_REGS
161 rtx set = single_set (insn);
162 if (set && STACK_REG_P (SET_DEST (set)))
163 cost += COSTS_N_INSNS (1);
165 #endif
167 count += cost;
168 if (count >= max_cost)
169 return false;
171 else if (CALL_P (insn))
172 return false;
174 if (insn == BB_END (bb))
175 break;
176 insn = NEXT_INSN (insn);
179 return true;
182 /* Return the first non-jump active insn in the basic block. */
184 static rtx
185 first_active_insn (basic_block bb)
187 rtx insn = BB_HEAD (bb);
189 if (LABEL_P (insn))
191 if (insn == BB_END (bb))
192 return NULL_RTX;
193 insn = NEXT_INSN (insn);
196 while (NOTE_P (insn))
198 if (insn == BB_END (bb))
199 return NULL_RTX;
200 insn = NEXT_INSN (insn);
203 if (JUMP_P (insn))
204 return NULL_RTX;
206 return insn;
209 /* Return the last non-jump active (non-jump) insn in the basic block. */
211 static rtx
212 last_active_insn (basic_block bb, int skip_use_p)
214 rtx insn = BB_END (bb);
215 rtx head = BB_HEAD (bb);
217 while (NOTE_P (insn)
218 || JUMP_P (insn)
219 || (skip_use_p
220 && NONJUMP_INSN_P (insn)
221 && GET_CODE (PATTERN (insn)) == USE))
223 if (insn == head)
224 return NULL_RTX;
225 insn = PREV_INSN (insn);
228 if (LABEL_P (insn))
229 return NULL_RTX;
231 return insn;
234 /* Return the basic block reached by falling though the basic block BB. */
236 static basic_block
237 block_fallthru (basic_block bb)
239 edge e;
240 edge_iterator ei;
242 FOR_EACH_EDGE (e, ei, bb->succs)
243 if (e->flags & EDGE_FALLTHRU)
244 break;
246 return (e) ? e->dest : NULL_BLOCK;
249 /* Go through a bunch of insns, converting them to conditional
250 execution format if possible. Return TRUE if all of the non-note
251 insns were processed. */
253 static int
254 cond_exec_process_insns (ce_if_block_t *ce_info ATTRIBUTE_UNUSED,
255 /* if block information */rtx start,
256 /* first insn to look at */rtx end,
257 /* last insn to look at */rtx test,
258 /* conditional execution test */rtx prob_val,
259 /* probability of branch taken. */int mod_ok)
261 int must_be_last = FALSE;
262 rtx insn;
263 rtx xtest;
264 rtx pattern;
266 if (!start || !end)
267 return FALSE;
269 for (insn = start; ; insn = NEXT_INSN (insn))
271 if (NOTE_P (insn))
272 goto insn_done;
274 gcc_assert(NONJUMP_INSN_P (insn) || CALL_P (insn));
276 /* Remove USE insns that get in the way. */
277 if (reload_completed && GET_CODE (PATTERN (insn)) == USE)
279 /* ??? Ug. Actually unlinking the thing is problematic,
280 given what we'd have to coordinate with our callers. */
281 SET_INSN_DELETED (insn);
282 goto insn_done;
285 /* Last insn wasn't last? */
286 if (must_be_last)
287 return FALSE;
289 if (modified_in_p (test, insn))
291 if (!mod_ok)
292 return FALSE;
293 must_be_last = TRUE;
296 /* Now build the conditional form of the instruction. */
297 pattern = PATTERN (insn);
298 xtest = copy_rtx (test);
300 /* If this is already a COND_EXEC, rewrite the test to be an AND of the
301 two conditions. */
302 if (GET_CODE (pattern) == COND_EXEC)
304 if (GET_MODE (xtest) != GET_MODE (COND_EXEC_TEST (pattern)))
305 return FALSE;
307 xtest = gen_rtx_AND (GET_MODE (xtest), xtest,
308 COND_EXEC_TEST (pattern));
309 pattern = COND_EXEC_CODE (pattern);
312 pattern = gen_rtx_COND_EXEC (VOIDmode, xtest, pattern);
314 /* If the machine needs to modify the insn being conditionally executed,
315 say for example to force a constant integer operand into a temp
316 register, do so here. */
317 #ifdef IFCVT_MODIFY_INSN
318 IFCVT_MODIFY_INSN (ce_info, pattern, insn);
319 if (! pattern)
320 return FALSE;
321 #endif
323 validate_change (insn, &PATTERN (insn), pattern, 1);
325 if (CALL_P (insn) && prob_val)
326 validate_change (insn, &REG_NOTES (insn),
327 alloc_EXPR_LIST (REG_BR_PROB, prob_val,
328 REG_NOTES (insn)), 1);
330 insn_done:
331 if (insn == end)
332 break;
335 return TRUE;
338 /* Return the condition for a jump. Do not do any special processing. */
340 static rtx
341 cond_exec_get_condition (rtx jump)
343 rtx test_if, cond;
345 if (any_condjump_p (jump))
346 test_if = SET_SRC (pc_set (jump));
347 else
348 return NULL_RTX;
349 cond = XEXP (test_if, 0);
351 /* If this branches to JUMP_LABEL when the condition is false,
352 reverse the condition. */
353 if (GET_CODE (XEXP (test_if, 2)) == LABEL_REF
354 && XEXP (XEXP (test_if, 2), 0) == JUMP_LABEL (jump))
356 enum rtx_code rev = reversed_comparison_code (cond, jump);
357 if (rev == UNKNOWN)
358 return NULL_RTX;
360 cond = gen_rtx_fmt_ee (rev, GET_MODE (cond), XEXP (cond, 0),
361 XEXP (cond, 1));
364 return cond;
367 /* Given a simple IF-THEN or IF-THEN-ELSE block, attempt to convert it
368 to conditional execution. Return TRUE if we were successful at
369 converting the block. */
371 static int
372 cond_exec_process_if_block (ce_if_block_t * ce_info,
373 /* if block information */int do_multiple_p)
375 basic_block test_bb = ce_info->test_bb; /* last test block */
376 basic_block then_bb = ce_info->then_bb; /* THEN */
377 basic_block else_bb = ce_info->else_bb; /* ELSE or NULL */
378 rtx test_expr; /* expression in IF_THEN_ELSE that is tested */
379 rtx then_start; /* first insn in THEN block */
380 rtx then_end; /* last insn + 1 in THEN block */
381 rtx else_start = NULL_RTX; /* first insn in ELSE block or NULL */
382 rtx else_end = NULL_RTX; /* last insn + 1 in ELSE block */
383 int max; /* max # of insns to convert. */
384 int then_mod_ok; /* whether conditional mods are ok in THEN */
385 rtx true_expr; /* test for else block insns */
386 rtx false_expr; /* test for then block insns */
387 rtx true_prob_val; /* probability of else block */
388 rtx false_prob_val; /* probability of then block */
389 int n_insns;
390 enum rtx_code false_code;
392 /* If test is comprised of && or || elements, and we've failed at handling
393 all of them together, just use the last test if it is the special case of
394 && elements without an ELSE block. */
395 if (!do_multiple_p && ce_info->num_multiple_test_blocks)
397 if (else_bb || ! ce_info->and_and_p)
398 return FALSE;
400 ce_info->test_bb = test_bb = ce_info->last_test_bb;
401 ce_info->num_multiple_test_blocks = 0;
402 ce_info->num_and_and_blocks = 0;
403 ce_info->num_or_or_blocks = 0;
406 /* Find the conditional jump to the ELSE or JOIN part, and isolate
407 the test. */
408 test_expr = cond_exec_get_condition (BB_END (test_bb));
409 if (! test_expr)
410 return FALSE;
412 /* If the conditional jump is more than just a conditional jump,
413 then we can not do conditional execution conversion on this block. */
414 if (! onlyjump_p (BB_END (test_bb)))
415 return FALSE;
417 /* Collect the bounds of where we're to search, skipping any labels, jumps
418 and notes at the beginning and end of the block. Then count the total
419 number of insns and see if it is small enough to convert. */
420 then_start = first_active_insn (then_bb);
421 then_end = last_active_insn (then_bb, TRUE);
422 n_insns = ce_info->num_then_insns = count_bb_insns (then_bb);
423 max = MAX_CONDITIONAL_EXECUTE;
425 if (else_bb)
427 max *= 2;
428 else_start = first_active_insn (else_bb);
429 else_end = last_active_insn (else_bb, TRUE);
430 n_insns += ce_info->num_else_insns = count_bb_insns (else_bb);
433 if (n_insns > max)
434 return FALSE;
436 /* Map test_expr/test_jump into the appropriate MD tests to use on
437 the conditionally executed code. */
439 true_expr = test_expr;
441 false_code = reversed_comparison_code (true_expr, BB_END (test_bb));
442 if (false_code != UNKNOWN)
443 false_expr = gen_rtx_fmt_ee (false_code, GET_MODE (true_expr),
444 XEXP (true_expr, 0), XEXP (true_expr, 1));
445 else
446 false_expr = NULL_RTX;
448 #ifdef IFCVT_MODIFY_TESTS
449 /* If the machine description needs to modify the tests, such as setting a
450 conditional execution register from a comparison, it can do so here. */
451 IFCVT_MODIFY_TESTS (ce_info, true_expr, false_expr);
453 /* See if the conversion failed. */
454 if (!true_expr || !false_expr)
455 goto fail;
456 #endif
458 true_prob_val = find_reg_note (BB_END (test_bb), REG_BR_PROB, NULL_RTX);
459 if (true_prob_val)
461 true_prob_val = XEXP (true_prob_val, 0);
462 false_prob_val = GEN_INT (REG_BR_PROB_BASE - INTVAL (true_prob_val));
464 else
465 false_prob_val = NULL_RTX;
467 /* If we have && or || tests, do them here. These tests are in the adjacent
468 blocks after the first block containing the test. */
469 if (ce_info->num_multiple_test_blocks > 0)
471 basic_block bb = test_bb;
472 basic_block last_test_bb = ce_info->last_test_bb;
474 if (! false_expr)
475 goto fail;
479 rtx start, end;
480 rtx t, f;
481 enum rtx_code f_code;
483 bb = block_fallthru (bb);
484 start = first_active_insn (bb);
485 end = last_active_insn (bb, TRUE);
486 if (start
487 && ! cond_exec_process_insns (ce_info, start, end, false_expr,
488 false_prob_val, FALSE))
489 goto fail;
491 /* If the conditional jump is more than just a conditional jump, then
492 we can not do conditional execution conversion on this block. */
493 if (! onlyjump_p (BB_END (bb)))
494 goto fail;
496 /* Find the conditional jump and isolate the test. */
497 t = cond_exec_get_condition (BB_END (bb));
498 if (! t)
499 goto fail;
501 f_code = reversed_comparison_code (t, BB_END (bb));
502 if (f_code == UNKNOWN)
503 goto fail;
505 f = gen_rtx_fmt_ee (f_code, GET_MODE (t), XEXP (t, 0), XEXP (t, 1));
506 if (ce_info->and_and_p)
508 t = gen_rtx_AND (GET_MODE (t), true_expr, t);
509 f = gen_rtx_IOR (GET_MODE (t), false_expr, f);
511 else
513 t = gen_rtx_IOR (GET_MODE (t), true_expr, t);
514 f = gen_rtx_AND (GET_MODE (t), false_expr, f);
517 /* If the machine description needs to modify the tests, such as
518 setting a conditional execution register from a comparison, it can
519 do so here. */
520 #ifdef IFCVT_MODIFY_MULTIPLE_TESTS
521 IFCVT_MODIFY_MULTIPLE_TESTS (ce_info, bb, t, f);
523 /* See if the conversion failed. */
524 if (!t || !f)
525 goto fail;
526 #endif
528 true_expr = t;
529 false_expr = f;
531 while (bb != last_test_bb);
534 /* For IF-THEN-ELSE blocks, we don't allow modifications of the test
535 on then THEN block. */
536 then_mod_ok = (else_bb == NULL_BLOCK);
538 /* Go through the THEN and ELSE blocks converting the insns if possible
539 to conditional execution. */
541 if (then_end
542 && (! false_expr
543 || ! cond_exec_process_insns (ce_info, then_start, then_end,
544 false_expr, false_prob_val,
545 then_mod_ok)))
546 goto fail;
548 if (else_bb && else_end
549 && ! cond_exec_process_insns (ce_info, else_start, else_end,
550 true_expr, true_prob_val, TRUE))
551 goto fail;
553 /* If we cannot apply the changes, fail. Do not go through the normal fail
554 processing, since apply_change_group will call cancel_changes. */
555 if (! apply_change_group ())
557 #ifdef IFCVT_MODIFY_CANCEL
558 /* Cancel any machine dependent changes. */
559 IFCVT_MODIFY_CANCEL (ce_info);
560 #endif
561 return FALSE;
564 #ifdef IFCVT_MODIFY_FINAL
565 /* Do any machine dependent final modifications. */
566 IFCVT_MODIFY_FINAL (ce_info);
567 #endif
569 /* Conversion succeeded. */
570 if (dump_file)
571 fprintf (dump_file, "%d insn%s converted to conditional execution.\n",
572 n_insns, (n_insns == 1) ? " was" : "s were");
574 /* Merge the blocks! */
575 merge_if_block (ce_info);
576 cond_exec_changed_p = TRUE;
577 return TRUE;
579 fail:
580 #ifdef IFCVT_MODIFY_CANCEL
581 /* Cancel any machine dependent changes. */
582 IFCVT_MODIFY_CANCEL (ce_info);
583 #endif
585 cancel_changes (0);
586 return FALSE;
589 /* Used by noce_process_if_block to communicate with its subroutines.
591 The subroutines know that A and B may be evaluated freely. They
592 know that X is a register. They should insert new instructions
593 before cond_earliest. */
595 struct noce_if_info
597 basic_block test_bb;
598 rtx insn_a, insn_b;
599 rtx x, a, b;
600 rtx jump, cond, cond_earliest;
601 /* True if "b" was originally evaluated unconditionally. */
602 bool b_unconditional;
605 static rtx noce_emit_store_flag (struct noce_if_info *, rtx, int, int);
606 static int noce_try_move (struct noce_if_info *);
607 static int noce_try_store_flag (struct noce_if_info *);
608 static int noce_try_addcc (struct noce_if_info *);
609 static int noce_try_store_flag_constants (struct noce_if_info *);
610 static int noce_try_store_flag_mask (struct noce_if_info *);
611 static rtx noce_emit_cmove (struct noce_if_info *, rtx, enum rtx_code, rtx,
612 rtx, rtx, rtx);
613 static int noce_try_cmove (struct noce_if_info *);
614 static int noce_try_cmove_arith (struct noce_if_info *);
615 static rtx noce_get_alt_condition (struct noce_if_info *, rtx, rtx *);
616 static int noce_try_minmax (struct noce_if_info *);
617 static int noce_try_abs (struct noce_if_info *);
618 static int noce_try_sign_mask (struct noce_if_info *);
620 /* Helper function for noce_try_store_flag*. */
622 static rtx
623 noce_emit_store_flag (struct noce_if_info *if_info, rtx x, int reversep,
624 int normalize)
626 rtx cond = if_info->cond;
627 int cond_complex;
628 enum rtx_code code;
630 cond_complex = (! general_operand (XEXP (cond, 0), VOIDmode)
631 || ! general_operand (XEXP (cond, 1), VOIDmode));
633 /* If earliest == jump, or when the condition is complex, try to
634 build the store_flag insn directly. */
636 if (cond_complex)
637 cond = XEXP (SET_SRC (pc_set (if_info->jump)), 0);
639 if (reversep)
640 code = reversed_comparison_code (cond, if_info->jump);
641 else
642 code = GET_CODE (cond);
644 if ((if_info->cond_earliest == if_info->jump || cond_complex)
645 && (normalize == 0 || STORE_FLAG_VALUE == normalize))
647 rtx tmp;
649 tmp = gen_rtx_fmt_ee (code, GET_MODE (x), XEXP (cond, 0),
650 XEXP (cond, 1));
651 tmp = gen_rtx_SET (VOIDmode, x, tmp);
653 start_sequence ();
654 tmp = emit_insn (tmp);
656 if (recog_memoized (tmp) >= 0)
658 tmp = get_insns ();
659 end_sequence ();
660 emit_insn (tmp);
662 if_info->cond_earliest = if_info->jump;
664 return x;
667 end_sequence ();
670 /* Don't even try if the comparison operands or the mode of X are weird. */
671 if (cond_complex || !SCALAR_INT_MODE_P (GET_MODE (x)))
672 return NULL_RTX;
674 return emit_store_flag (x, code, XEXP (cond, 0),
675 XEXP (cond, 1), VOIDmode,
676 (code == LTU || code == LEU
677 || code == GEU || code == GTU), normalize);
680 /* Emit instruction to move an rtx, possibly into STRICT_LOW_PART.
681 X is the destination/target and Y is the value to copy. */
683 static void
684 noce_emit_move_insn (rtx x, rtx y)
686 enum machine_mode outmode;
687 rtx outer, inner;
688 int bitpos;
690 if (GET_CODE (x) != STRICT_LOW_PART)
692 rtx seq, insn, target;
693 optab ot;
695 start_sequence ();
696 /* Check that the SET_SRC is reasonable before calling emit_move_insn,
697 otherwise construct a suitable SET pattern ourselves. */
698 insn = (OBJECT_P (y) || CONSTANT_P (y) || GET_CODE (y) == SUBREG)
699 ? emit_move_insn (x, y)
700 : emit_insn (gen_rtx_SET (VOIDmode, x, y));
701 seq = get_insns ();
702 end_sequence();
704 if (recog_memoized (insn) <= 0)
705 switch (GET_RTX_CLASS (GET_CODE (y)))
707 case RTX_UNARY:
708 ot = code_to_optab[GET_CODE (y)];
709 if (ot)
711 start_sequence ();
712 target = expand_unop (GET_MODE (y), ot, XEXP (y, 0), x, 0);
713 if (target != NULL_RTX)
715 if (target != x)
716 emit_move_insn (x, target);
717 seq = get_insns ();
719 end_sequence ();
721 break;
723 case RTX_BIN_ARITH:
724 case RTX_COMM_ARITH:
725 ot = code_to_optab[GET_CODE (y)];
726 if (ot)
728 start_sequence ();
729 target = expand_binop (GET_MODE (y), ot,
730 XEXP (y, 0), XEXP (y, 1),
731 x, 0, OPTAB_DIRECT);
732 if (target != NULL_RTX)
734 if (target != x)
735 emit_move_insn (x, target);
736 seq = get_insns ();
738 end_sequence ();
740 break;
742 default:
743 break;
746 emit_insn (seq);
747 return;
750 outer = XEXP (x, 0);
751 inner = XEXP (outer, 0);
752 outmode = GET_MODE (outer);
753 bitpos = SUBREG_BYTE (outer) * BITS_PER_UNIT;
754 store_bit_field (inner, GET_MODE_BITSIZE (outmode), bitpos, outmode, y);
757 /* Return sequence of instructions generated by if conversion. This
758 function calls end_sequence() to end the current stream, ensures
759 that are instructions are unshared, recognizable non-jump insns.
760 On failure, this function returns a NULL_RTX. */
762 static rtx
763 end_ifcvt_sequence (struct noce_if_info *if_info)
765 rtx insn;
766 rtx seq = get_insns ();
768 set_used_flags (if_info->x);
769 set_used_flags (if_info->cond);
770 unshare_all_rtl_in_chain (seq);
771 end_sequence ();
773 /* Make sure that all of the instructions emitted are recognizable,
774 and that we haven't introduced a new jump instruction.
775 As an exercise for the reader, build a general mechanism that
776 allows proper placement of required clobbers. */
777 for (insn = seq; insn; insn = NEXT_INSN (insn))
778 if (JUMP_P (insn)
779 || recog_memoized (insn) == -1)
780 return NULL_RTX;
782 return seq;
785 /* Convert "if (a != b) x = a; else x = b" into "x = a" and
786 "if (a == b) x = a; else x = b" into "x = b". */
788 static int
789 noce_try_move (struct noce_if_info *if_info)
791 rtx cond = if_info->cond;
792 enum rtx_code code = GET_CODE (cond);
793 rtx y, seq;
795 if (code != NE && code != EQ)
796 return FALSE;
798 /* This optimization isn't valid if either A or B could be a NaN
799 or a signed zero. */
800 if (HONOR_NANS (GET_MODE (if_info->x))
801 || HONOR_SIGNED_ZEROS (GET_MODE (if_info->x)))
802 return FALSE;
804 /* Check whether the operands of the comparison are A and in
805 either order. */
806 if ((rtx_equal_p (if_info->a, XEXP (cond, 0))
807 && rtx_equal_p (if_info->b, XEXP (cond, 1)))
808 || (rtx_equal_p (if_info->a, XEXP (cond, 1))
809 && rtx_equal_p (if_info->b, XEXP (cond, 0))))
811 y = (code == EQ) ? if_info->a : if_info->b;
813 /* Avoid generating the move if the source is the destination. */
814 if (! rtx_equal_p (if_info->x, y))
816 start_sequence ();
817 noce_emit_move_insn (if_info->x, y);
818 seq = end_ifcvt_sequence (if_info);
819 if (!seq)
820 return FALSE;
822 emit_insn_before_setloc (seq, if_info->jump,
823 INSN_LOCATOR (if_info->insn_a));
825 return TRUE;
827 return FALSE;
830 /* Convert "if (test) x = 1; else x = 0".
832 Only try 0 and STORE_FLAG_VALUE here. Other combinations will be
833 tried in noce_try_store_flag_constants after noce_try_cmove has had
834 a go at the conversion. */
836 static int
837 noce_try_store_flag (struct noce_if_info *if_info)
839 int reversep;
840 rtx target, seq;
842 if (GET_CODE (if_info->b) == CONST_INT
843 && INTVAL (if_info->b) == STORE_FLAG_VALUE
844 && if_info->a == const0_rtx)
845 reversep = 0;
846 else if (if_info->b == const0_rtx
847 && GET_CODE (if_info->a) == CONST_INT
848 && INTVAL (if_info->a) == STORE_FLAG_VALUE
849 && (reversed_comparison_code (if_info->cond, if_info->jump)
850 != UNKNOWN))
851 reversep = 1;
852 else
853 return FALSE;
855 start_sequence ();
857 target = noce_emit_store_flag (if_info, if_info->x, reversep, 0);
858 if (target)
860 if (target != if_info->x)
861 noce_emit_move_insn (if_info->x, target);
863 seq = end_ifcvt_sequence (if_info);
864 if (! seq)
865 return FALSE;
867 emit_insn_before_setloc (seq, if_info->jump,
868 INSN_LOCATOR (if_info->insn_a));
869 return TRUE;
871 else
873 end_sequence ();
874 return FALSE;
878 /* Convert "if (test) x = a; else x = b", for A and B constant. */
880 static int
881 noce_try_store_flag_constants (struct noce_if_info *if_info)
883 rtx target, seq;
884 int reversep;
885 HOST_WIDE_INT itrue, ifalse, diff, tmp;
886 int normalize, can_reverse;
887 enum machine_mode mode;
889 if (! no_new_pseudos
890 && GET_CODE (if_info->a) == CONST_INT
891 && GET_CODE (if_info->b) == CONST_INT)
893 mode = GET_MODE (if_info->x);
894 ifalse = INTVAL (if_info->a);
895 itrue = INTVAL (if_info->b);
897 /* Make sure we can represent the difference between the two values. */
898 if ((itrue - ifalse > 0)
899 != ((ifalse < 0) != (itrue < 0) ? ifalse < 0 : ifalse < itrue))
900 return FALSE;
902 diff = trunc_int_for_mode (itrue - ifalse, mode);
904 can_reverse = (reversed_comparison_code (if_info->cond, if_info->jump)
905 != UNKNOWN);
907 reversep = 0;
908 if (diff == STORE_FLAG_VALUE || diff == -STORE_FLAG_VALUE)
909 normalize = 0;
910 else if (ifalse == 0 && exact_log2 (itrue) >= 0
911 && (STORE_FLAG_VALUE == 1
912 || BRANCH_COST >= 2))
913 normalize = 1;
914 else if (itrue == 0 && exact_log2 (ifalse) >= 0 && can_reverse
915 && (STORE_FLAG_VALUE == 1 || BRANCH_COST >= 2))
916 normalize = 1, reversep = 1;
917 else if (itrue == -1
918 && (STORE_FLAG_VALUE == -1
919 || BRANCH_COST >= 2))
920 normalize = -1;
921 else if (ifalse == -1 && can_reverse
922 && (STORE_FLAG_VALUE == -1 || BRANCH_COST >= 2))
923 normalize = -1, reversep = 1;
924 else if ((BRANCH_COST >= 2 && STORE_FLAG_VALUE == -1)
925 || BRANCH_COST >= 3)
926 normalize = -1;
927 else
928 return FALSE;
930 if (reversep)
932 tmp = itrue; itrue = ifalse; ifalse = tmp;
933 diff = trunc_int_for_mode (-diff, mode);
936 start_sequence ();
937 target = noce_emit_store_flag (if_info, if_info->x, reversep, normalize);
938 if (! target)
940 end_sequence ();
941 return FALSE;
944 /* if (test) x = 3; else x = 4;
945 => x = 3 + (test == 0); */
946 if (diff == STORE_FLAG_VALUE || diff == -STORE_FLAG_VALUE)
948 target = expand_simple_binop (mode,
949 (diff == STORE_FLAG_VALUE
950 ? PLUS : MINUS),
951 GEN_INT (ifalse), target, if_info->x, 0,
952 OPTAB_WIDEN);
955 /* if (test) x = 8; else x = 0;
956 => x = (test != 0) << 3; */
957 else if (ifalse == 0 && (tmp = exact_log2 (itrue)) >= 0)
959 target = expand_simple_binop (mode, ASHIFT,
960 target, GEN_INT (tmp), if_info->x, 0,
961 OPTAB_WIDEN);
964 /* if (test) x = -1; else x = b;
965 => x = -(test != 0) | b; */
966 else if (itrue == -1)
968 target = expand_simple_binop (mode, IOR,
969 target, GEN_INT (ifalse), if_info->x, 0,
970 OPTAB_WIDEN);
973 /* if (test) x = a; else x = b;
974 => x = (-(test != 0) & (b - a)) + a; */
975 else
977 target = expand_simple_binop (mode, AND,
978 target, GEN_INT (diff), if_info->x, 0,
979 OPTAB_WIDEN);
980 if (target)
981 target = expand_simple_binop (mode, PLUS,
982 target, GEN_INT (ifalse),
983 if_info->x, 0, OPTAB_WIDEN);
986 if (! target)
988 end_sequence ();
989 return FALSE;
992 if (target != if_info->x)
993 noce_emit_move_insn (if_info->x, target);
995 seq = end_ifcvt_sequence (if_info);
996 if (!seq)
997 return FALSE;
999 emit_insn_before_setloc (seq, if_info->jump,
1000 INSN_LOCATOR (if_info->insn_a));
1001 return TRUE;
1004 return FALSE;
1007 /* Convert "if (test) foo++" into "foo += (test != 0)", and
1008 similarly for "foo--". */
1010 static int
1011 noce_try_addcc (struct noce_if_info *if_info)
1013 rtx target, seq;
1014 int subtract, normalize;
1016 if (! no_new_pseudos
1017 && GET_CODE (if_info->a) == PLUS
1018 && rtx_equal_p (XEXP (if_info->a, 0), if_info->b)
1019 && (reversed_comparison_code (if_info->cond, if_info->jump)
1020 != UNKNOWN))
1022 rtx cond = if_info->cond;
1023 enum rtx_code code = reversed_comparison_code (cond, if_info->jump);
1025 /* First try to use addcc pattern. */
1026 if (general_operand (XEXP (cond, 0), VOIDmode)
1027 && general_operand (XEXP (cond, 1), VOIDmode))
1029 start_sequence ();
1030 target = emit_conditional_add (if_info->x, code,
1031 XEXP (cond, 0),
1032 XEXP (cond, 1),
1033 VOIDmode,
1034 if_info->b,
1035 XEXP (if_info->a, 1),
1036 GET_MODE (if_info->x),
1037 (code == LTU || code == GEU
1038 || code == LEU || code == GTU));
1039 if (target)
1041 if (target != if_info->x)
1042 noce_emit_move_insn (if_info->x, target);
1044 seq = end_ifcvt_sequence (if_info);
1045 if (!seq)
1046 return FALSE;
1048 emit_insn_before_setloc (seq, if_info->jump,
1049 INSN_LOCATOR (if_info->insn_a));
1050 return TRUE;
1052 end_sequence ();
1055 /* If that fails, construct conditional increment or decrement using
1056 setcc. */
1057 if (BRANCH_COST >= 2
1058 && (XEXP (if_info->a, 1) == const1_rtx
1059 || XEXP (if_info->a, 1) == constm1_rtx))
1061 start_sequence ();
1062 if (STORE_FLAG_VALUE == INTVAL (XEXP (if_info->a, 1)))
1063 subtract = 0, normalize = 0;
1064 else if (-STORE_FLAG_VALUE == INTVAL (XEXP (if_info->a, 1)))
1065 subtract = 1, normalize = 0;
1066 else
1067 subtract = 0, normalize = INTVAL (XEXP (if_info->a, 1));
1070 target = noce_emit_store_flag (if_info,
1071 gen_reg_rtx (GET_MODE (if_info->x)),
1072 1, normalize);
1074 if (target)
1075 target = expand_simple_binop (GET_MODE (if_info->x),
1076 subtract ? MINUS : PLUS,
1077 if_info->b, target, if_info->x,
1078 0, OPTAB_WIDEN);
1079 if (target)
1081 if (target != if_info->x)
1082 noce_emit_move_insn (if_info->x, target);
1084 seq = end_ifcvt_sequence (if_info);
1085 if (!seq)
1086 return FALSE;
1088 emit_insn_before_setloc (seq, if_info->jump,
1089 INSN_LOCATOR (if_info->insn_a));
1090 return TRUE;
1092 end_sequence ();
1096 return FALSE;
1099 /* Convert "if (test) x = 0;" to "x &= -(test == 0);" */
1101 static int
1102 noce_try_store_flag_mask (struct noce_if_info *if_info)
1104 rtx target, seq;
1105 int reversep;
1107 reversep = 0;
1108 if (! no_new_pseudos
1109 && (BRANCH_COST >= 2
1110 || STORE_FLAG_VALUE == -1)
1111 && ((if_info->a == const0_rtx
1112 && rtx_equal_p (if_info->b, if_info->x))
1113 || ((reversep = (reversed_comparison_code (if_info->cond,
1114 if_info->jump)
1115 != UNKNOWN))
1116 && if_info->b == const0_rtx
1117 && rtx_equal_p (if_info->a, if_info->x))))
1119 start_sequence ();
1120 target = noce_emit_store_flag (if_info,
1121 gen_reg_rtx (GET_MODE (if_info->x)),
1122 reversep, -1);
1123 if (target)
1124 target = expand_simple_binop (GET_MODE (if_info->x), AND,
1125 if_info->x,
1126 target, if_info->x, 0,
1127 OPTAB_WIDEN);
1129 if (target)
1131 if (target != if_info->x)
1132 noce_emit_move_insn (if_info->x, target);
1134 seq = end_ifcvt_sequence (if_info);
1135 if (!seq)
1136 return FALSE;
1138 emit_insn_before_setloc (seq, if_info->jump,
1139 INSN_LOCATOR (if_info->insn_a));
1140 return TRUE;
1143 end_sequence ();
1146 return FALSE;
1149 /* Helper function for noce_try_cmove and noce_try_cmove_arith. */
1151 static rtx
1152 noce_emit_cmove (struct noce_if_info *if_info, rtx x, enum rtx_code code,
1153 rtx cmp_a, rtx cmp_b, rtx vfalse, rtx vtrue)
1155 /* If earliest == jump, try to build the cmove insn directly.
1156 This is helpful when combine has created some complex condition
1157 (like for alpha's cmovlbs) that we can't hope to regenerate
1158 through the normal interface. */
1160 if (if_info->cond_earliest == if_info->jump)
1162 rtx tmp;
1164 tmp = gen_rtx_fmt_ee (code, GET_MODE (if_info->cond), cmp_a, cmp_b);
1165 tmp = gen_rtx_IF_THEN_ELSE (GET_MODE (x), tmp, vtrue, vfalse);
1166 tmp = gen_rtx_SET (VOIDmode, x, tmp);
1168 start_sequence ();
1169 tmp = emit_insn (tmp);
1171 if (recog_memoized (tmp) >= 0)
1173 tmp = get_insns ();
1174 end_sequence ();
1175 emit_insn (tmp);
1177 return x;
1180 end_sequence ();
1183 /* Don't even try if the comparison operands are weird. */
1184 if (! general_operand (cmp_a, GET_MODE (cmp_a))
1185 || ! general_operand (cmp_b, GET_MODE (cmp_b)))
1186 return NULL_RTX;
1188 #if HAVE_conditional_move
1189 return emit_conditional_move (x, code, cmp_a, cmp_b, VOIDmode,
1190 vtrue, vfalse, GET_MODE (x),
1191 (code == LTU || code == GEU
1192 || code == LEU || code == GTU));
1193 #else
1194 /* We'll never get here, as noce_process_if_block doesn't call the
1195 functions involved. Ifdef code, however, should be discouraged
1196 because it leads to typos in the code not selected. However,
1197 emit_conditional_move won't exist either. */
1198 return NULL_RTX;
1199 #endif
1202 /* Try only simple constants and registers here. More complex cases
1203 are handled in noce_try_cmove_arith after noce_try_store_flag_arith
1204 has had a go at it. */
1206 static int
1207 noce_try_cmove (struct noce_if_info *if_info)
1209 enum rtx_code code;
1210 rtx target, seq;
1212 if ((CONSTANT_P (if_info->a) || register_operand (if_info->a, VOIDmode))
1213 && (CONSTANT_P (if_info->b) || register_operand (if_info->b, VOIDmode)))
1215 start_sequence ();
1217 code = GET_CODE (if_info->cond);
1218 target = noce_emit_cmove (if_info, if_info->x, code,
1219 XEXP (if_info->cond, 0),
1220 XEXP (if_info->cond, 1),
1221 if_info->a, if_info->b);
1223 if (target)
1225 if (target != if_info->x)
1226 noce_emit_move_insn (if_info->x, target);
1228 seq = end_ifcvt_sequence (if_info);
1229 if (!seq)
1230 return FALSE;
1232 emit_insn_before_setloc (seq, if_info->jump,
1233 INSN_LOCATOR (if_info->insn_a));
1234 return TRUE;
1236 else
1238 end_sequence ();
1239 return FALSE;
1243 return FALSE;
1246 /* Try more complex cases involving conditional_move. */
1248 static int
1249 noce_try_cmove_arith (struct noce_if_info *if_info)
1251 rtx a = if_info->a;
1252 rtx b = if_info->b;
1253 rtx x = if_info->x;
1254 rtx orig_a, orig_b;
1255 rtx insn_a, insn_b;
1256 rtx tmp, target;
1257 int is_mem = 0;
1258 int insn_cost;
1259 enum rtx_code code;
1261 /* A conditional move from two memory sources is equivalent to a
1262 conditional on their addresses followed by a load. Don't do this
1263 early because it'll screw alias analysis. Note that we've
1264 already checked for no side effects. */
1265 if (! no_new_pseudos && cse_not_expected
1266 && MEM_P (a) && MEM_P (b)
1267 && BRANCH_COST >= 5)
1269 a = XEXP (a, 0);
1270 b = XEXP (b, 0);
1271 x = gen_reg_rtx (Pmode);
1272 is_mem = 1;
1275 /* ??? We could handle this if we knew that a load from A or B could
1276 not fault. This is also true if we've already loaded
1277 from the address along the path from ENTRY. */
1278 else if (may_trap_p (a) || may_trap_p (b))
1279 return FALSE;
1281 /* if (test) x = a + b; else x = c - d;
1282 => y = a + b;
1283 x = c - d;
1284 if (test)
1285 x = y;
1288 code = GET_CODE (if_info->cond);
1289 insn_a = if_info->insn_a;
1290 insn_b = if_info->insn_b;
1292 /* Total insn_rtx_cost should be smaller than branch cost. Exit
1293 if insn_rtx_cost can't be estimated. */
1294 if (insn_a)
1296 insn_cost = insn_rtx_cost (PATTERN (insn_a));
1297 if (insn_cost == 0 || insn_cost > COSTS_N_INSNS (BRANCH_COST))
1298 return FALSE;
1300 else
1302 insn_cost = 0;
1305 if (insn_b) {
1306 insn_cost += insn_rtx_cost (PATTERN (insn_b));
1307 if (insn_cost == 0 || insn_cost > COSTS_N_INSNS (BRANCH_COST))
1308 return FALSE;
1311 /* Possibly rearrange operands to make things come out more natural. */
1312 if (reversed_comparison_code (if_info->cond, if_info->jump) != UNKNOWN)
1314 int reversep = 0;
1315 if (rtx_equal_p (b, x))
1316 reversep = 1;
1317 else if (general_operand (b, GET_MODE (b)))
1318 reversep = 1;
1320 if (reversep)
1322 code = reversed_comparison_code (if_info->cond, if_info->jump);
1323 tmp = a, a = b, b = tmp;
1324 tmp = insn_a, insn_a = insn_b, insn_b = tmp;
1328 start_sequence ();
1330 orig_a = a;
1331 orig_b = b;
1333 /* If either operand is complex, load it into a register first.
1334 The best way to do this is to copy the original insn. In this
1335 way we preserve any clobbers etc that the insn may have had.
1336 This is of course not possible in the IS_MEM case. */
1337 if (! general_operand (a, GET_MODE (a)))
1339 rtx set;
1341 if (no_new_pseudos)
1342 goto end_seq_and_fail;
1344 if (is_mem)
1346 tmp = gen_reg_rtx (GET_MODE (a));
1347 tmp = emit_insn (gen_rtx_SET (VOIDmode, tmp, a));
1349 else if (! insn_a)
1350 goto end_seq_and_fail;
1351 else
1353 a = gen_reg_rtx (GET_MODE (a));
1354 tmp = copy_rtx (insn_a);
1355 set = single_set (tmp);
1356 SET_DEST (set) = a;
1357 tmp = emit_insn (PATTERN (tmp));
1359 if (recog_memoized (tmp) < 0)
1360 goto end_seq_and_fail;
1362 if (! general_operand (b, GET_MODE (b)))
1364 rtx set, last;
1366 if (no_new_pseudos)
1367 goto end_seq_and_fail;
1369 if (is_mem)
1371 tmp = gen_reg_rtx (GET_MODE (b));
1372 tmp = gen_rtx_SET (VOIDmode, tmp, b);
1374 else if (! insn_b)
1375 goto end_seq_and_fail;
1376 else
1378 b = gen_reg_rtx (GET_MODE (b));
1379 tmp = copy_rtx (insn_b);
1380 set = single_set (tmp);
1381 SET_DEST (set) = b;
1382 tmp = PATTERN (tmp);
1385 /* If insn to set up A clobbers any registers B depends on, try to
1386 swap insn that sets up A with the one that sets up B. If even
1387 that doesn't help, punt. */
1388 last = get_last_insn ();
1389 if (last && modified_in_p (orig_b, last))
1391 tmp = emit_insn_before (tmp, get_insns ());
1392 if (modified_in_p (orig_a, tmp))
1393 goto end_seq_and_fail;
1395 else
1396 tmp = emit_insn (tmp);
1398 if (recog_memoized (tmp) < 0)
1399 goto end_seq_and_fail;
1402 target = noce_emit_cmove (if_info, x, code, XEXP (if_info->cond, 0),
1403 XEXP (if_info->cond, 1), a, b);
1405 if (! target)
1406 goto end_seq_and_fail;
1408 /* If we're handling a memory for above, emit the load now. */
1409 if (is_mem)
1411 tmp = gen_rtx_MEM (GET_MODE (if_info->x), target);
1413 /* Copy over flags as appropriate. */
1414 if (MEM_VOLATILE_P (if_info->a) || MEM_VOLATILE_P (if_info->b))
1415 MEM_VOLATILE_P (tmp) = 1;
1416 if (MEM_IN_STRUCT_P (if_info->a) && MEM_IN_STRUCT_P (if_info->b))
1417 MEM_IN_STRUCT_P (tmp) = 1;
1418 if (MEM_SCALAR_P (if_info->a) && MEM_SCALAR_P (if_info->b))
1419 MEM_SCALAR_P (tmp) = 1;
1420 if (MEM_ALIAS_SET (if_info->a) == MEM_ALIAS_SET (if_info->b))
1421 set_mem_alias_set (tmp, MEM_ALIAS_SET (if_info->a));
1422 set_mem_align (tmp,
1423 MIN (MEM_ALIGN (if_info->a), MEM_ALIGN (if_info->b)));
1425 noce_emit_move_insn (if_info->x, tmp);
1427 else if (target != x)
1428 noce_emit_move_insn (x, target);
1430 tmp = end_ifcvt_sequence (if_info);
1431 if (!tmp)
1432 return FALSE;
1434 emit_insn_before_setloc (tmp, if_info->jump, INSN_LOCATOR (if_info->insn_a));
1435 return TRUE;
1437 end_seq_and_fail:
1438 end_sequence ();
1439 return FALSE;
1442 /* For most cases, the simplified condition we found is the best
1443 choice, but this is not the case for the min/max/abs transforms.
1444 For these we wish to know that it is A or B in the condition. */
1446 static rtx
1447 noce_get_alt_condition (struct noce_if_info *if_info, rtx target,
1448 rtx *earliest)
1450 rtx cond, set, insn;
1451 int reverse;
1453 /* If target is already mentioned in the known condition, return it. */
1454 if (reg_mentioned_p (target, if_info->cond))
1456 *earliest = if_info->cond_earliest;
1457 return if_info->cond;
1460 set = pc_set (if_info->jump);
1461 cond = XEXP (SET_SRC (set), 0);
1462 reverse
1463 = GET_CODE (XEXP (SET_SRC (set), 2)) == LABEL_REF
1464 && XEXP (XEXP (SET_SRC (set), 2), 0) == JUMP_LABEL (if_info->jump);
1466 /* If we're looking for a constant, try to make the conditional
1467 have that constant in it. There are two reasons why it may
1468 not have the constant we want:
1470 1. GCC may have needed to put the constant in a register, because
1471 the target can't compare directly against that constant. For
1472 this case, we look for a SET immediately before the comparison
1473 that puts a constant in that register.
1475 2. GCC may have canonicalized the conditional, for example
1476 replacing "if x < 4" with "if x <= 3". We can undo that (or
1477 make equivalent types of changes) to get the constants we need
1478 if they're off by one in the right direction. */
1480 if (GET_CODE (target) == CONST_INT)
1482 enum rtx_code code = GET_CODE (if_info->cond);
1483 rtx op_a = XEXP (if_info->cond, 0);
1484 rtx op_b = XEXP (if_info->cond, 1);
1485 rtx prev_insn;
1487 /* First, look to see if we put a constant in a register. */
1488 prev_insn = prev_nonnote_insn (if_info->cond_earliest);
1489 if (prev_insn
1490 && INSN_P (prev_insn)
1491 && GET_CODE (PATTERN (prev_insn)) == SET)
1493 rtx src = find_reg_equal_equiv_note (prev_insn);
1494 if (!src)
1495 src = SET_SRC (PATTERN (prev_insn));
1496 if (GET_CODE (src) == CONST_INT)
1498 if (rtx_equal_p (op_a, SET_DEST (PATTERN (prev_insn))))
1499 op_a = src;
1500 else if (rtx_equal_p (op_b, SET_DEST (PATTERN (prev_insn))))
1501 op_b = src;
1503 if (GET_CODE (op_a) == CONST_INT)
1505 rtx tmp = op_a;
1506 op_a = op_b;
1507 op_b = tmp;
1508 code = swap_condition (code);
1513 /* Now, look to see if we can get the right constant by
1514 adjusting the conditional. */
1515 if (GET_CODE (op_b) == CONST_INT)
1517 HOST_WIDE_INT desired_val = INTVAL (target);
1518 HOST_WIDE_INT actual_val = INTVAL (op_b);
1520 switch (code)
1522 case LT:
1523 if (actual_val == desired_val + 1)
1525 code = LE;
1526 op_b = GEN_INT (desired_val);
1528 break;
1529 case LE:
1530 if (actual_val == desired_val - 1)
1532 code = LT;
1533 op_b = GEN_INT (desired_val);
1535 break;
1536 case GT:
1537 if (actual_val == desired_val - 1)
1539 code = GE;
1540 op_b = GEN_INT (desired_val);
1542 break;
1543 case GE:
1544 if (actual_val == desired_val + 1)
1546 code = GT;
1547 op_b = GEN_INT (desired_val);
1549 break;
1550 default:
1551 break;
1555 /* If we made any changes, generate a new conditional that is
1556 equivalent to what we started with, but has the right
1557 constants in it. */
1558 if (code != GET_CODE (if_info->cond)
1559 || op_a != XEXP (if_info->cond, 0)
1560 || op_b != XEXP (if_info->cond, 1))
1562 cond = gen_rtx_fmt_ee (code, GET_MODE (cond), op_a, op_b);
1563 *earliest = if_info->cond_earliest;
1564 return cond;
1568 cond = canonicalize_condition (if_info->jump, cond, reverse,
1569 earliest, target, false, true);
1570 if (! cond || ! reg_mentioned_p (target, cond))
1571 return NULL;
1573 /* We almost certainly searched back to a different place.
1574 Need to re-verify correct lifetimes. */
1576 /* X may not be mentioned in the range (cond_earliest, jump]. */
1577 for (insn = if_info->jump; insn != *earliest; insn = PREV_INSN (insn))
1578 if (INSN_P (insn) && reg_overlap_mentioned_p (if_info->x, PATTERN (insn)))
1579 return NULL;
1581 /* A and B may not be modified in the range [cond_earliest, jump). */
1582 for (insn = *earliest; insn != if_info->jump; insn = NEXT_INSN (insn))
1583 if (INSN_P (insn)
1584 && (modified_in_p (if_info->a, insn)
1585 || modified_in_p (if_info->b, insn)))
1586 return NULL;
1588 return cond;
1591 /* Convert "if (a < b) x = a; else x = b;" to "x = min(a, b);", etc. */
1593 static int
1594 noce_try_minmax (struct noce_if_info *if_info)
1596 rtx cond, earliest, target, seq;
1597 enum rtx_code code, op;
1598 int unsignedp;
1600 /* ??? Can't guarantee that expand_binop won't create pseudos. */
1601 if (no_new_pseudos)
1602 return FALSE;
1604 /* ??? Reject modes with NaNs or signed zeros since we don't know how
1605 they will be resolved with an SMIN/SMAX. It wouldn't be too hard
1606 to get the target to tell us... */
1607 if (HONOR_SIGNED_ZEROS (GET_MODE (if_info->x))
1608 || HONOR_NANS (GET_MODE (if_info->x)))
1609 return FALSE;
1611 cond = noce_get_alt_condition (if_info, if_info->a, &earliest);
1612 if (!cond)
1613 return FALSE;
1615 /* Verify the condition is of the form we expect, and canonicalize
1616 the comparison code. */
1617 code = GET_CODE (cond);
1618 if (rtx_equal_p (XEXP (cond, 0), if_info->a))
1620 if (! rtx_equal_p (XEXP (cond, 1), if_info->b))
1621 return FALSE;
1623 else if (rtx_equal_p (XEXP (cond, 1), if_info->a))
1625 if (! rtx_equal_p (XEXP (cond, 0), if_info->b))
1626 return FALSE;
1627 code = swap_condition (code);
1629 else
1630 return FALSE;
1632 /* Determine what sort of operation this is. Note that the code is for
1633 a taken branch, so the code->operation mapping appears backwards. */
1634 switch (code)
1636 case LT:
1637 case LE:
1638 case UNLT:
1639 case UNLE:
1640 op = SMAX;
1641 unsignedp = 0;
1642 break;
1643 case GT:
1644 case GE:
1645 case UNGT:
1646 case UNGE:
1647 op = SMIN;
1648 unsignedp = 0;
1649 break;
1650 case LTU:
1651 case LEU:
1652 op = UMAX;
1653 unsignedp = 1;
1654 break;
1655 case GTU:
1656 case GEU:
1657 op = UMIN;
1658 unsignedp = 1;
1659 break;
1660 default:
1661 return FALSE;
1664 start_sequence ();
1666 target = expand_simple_binop (GET_MODE (if_info->x), op,
1667 if_info->a, if_info->b,
1668 if_info->x, unsignedp, OPTAB_WIDEN);
1669 if (! target)
1671 end_sequence ();
1672 return FALSE;
1674 if (target != if_info->x)
1675 noce_emit_move_insn (if_info->x, target);
1677 seq = end_ifcvt_sequence (if_info);
1678 if (!seq)
1679 return FALSE;
1681 emit_insn_before_setloc (seq, if_info->jump, INSN_LOCATOR (if_info->insn_a));
1682 if_info->cond = cond;
1683 if_info->cond_earliest = earliest;
1685 return TRUE;
1688 /* Convert "if (a < 0) x = -a; else x = a;" to "x = abs(a);", etc. */
1690 static int
1691 noce_try_abs (struct noce_if_info *if_info)
1693 rtx cond, earliest, target, seq, a, b, c;
1694 int negate;
1696 /* ??? Can't guarantee that expand_binop won't create pseudos. */
1697 if (no_new_pseudos)
1698 return FALSE;
1700 /* Recognize A and B as constituting an ABS or NABS. The canonical
1701 form is a branch around the negation, taken when the object is the
1702 first operand of a comparison against 0 that evaluates to true. */
1703 a = if_info->a;
1704 b = if_info->b;
1705 if (GET_CODE (a) == NEG && rtx_equal_p (XEXP (a, 0), b))
1706 negate = 0;
1707 else if (GET_CODE (b) == NEG && rtx_equal_p (XEXP (b, 0), a))
1709 c = a; a = b; b = c;
1710 negate = 1;
1712 else
1713 return FALSE;
1715 cond = noce_get_alt_condition (if_info, b, &earliest);
1716 if (!cond)
1717 return FALSE;
1719 /* Verify the condition is of the form we expect. */
1720 if (rtx_equal_p (XEXP (cond, 0), b))
1721 c = XEXP (cond, 1);
1722 else if (rtx_equal_p (XEXP (cond, 1), b))
1724 c = XEXP (cond, 0);
1725 negate = !negate;
1727 else
1728 return FALSE;
1730 /* Verify that C is zero. Search one step backward for a
1731 REG_EQUAL note or a simple source if necessary. */
1732 if (REG_P (c))
1734 rtx set, insn = prev_nonnote_insn (earliest);
1735 if (insn
1736 && (set = single_set (insn))
1737 && rtx_equal_p (SET_DEST (set), c))
1739 rtx note = find_reg_equal_equiv_note (insn);
1740 if (note)
1741 c = XEXP (note, 0);
1742 else
1743 c = SET_SRC (set);
1745 else
1746 return FALSE;
1748 if (MEM_P (c)
1749 && GET_CODE (XEXP (c, 0)) == SYMBOL_REF
1750 && CONSTANT_POOL_ADDRESS_P (XEXP (c, 0)))
1751 c = get_pool_constant (XEXP (c, 0));
1753 /* Work around funny ideas get_condition has wrt canonicalization.
1754 Note that these rtx constants are known to be CONST_INT, and
1755 therefore imply integer comparisons. */
1756 if (c == constm1_rtx && GET_CODE (cond) == GT)
1758 else if (c == const1_rtx && GET_CODE (cond) == LT)
1760 else if (c != CONST0_RTX (GET_MODE (b)))
1761 return FALSE;
1763 /* Determine what sort of operation this is. */
1764 switch (GET_CODE (cond))
1766 case LT:
1767 case LE:
1768 case UNLT:
1769 case UNLE:
1770 negate = !negate;
1771 break;
1772 case GT:
1773 case GE:
1774 case UNGT:
1775 case UNGE:
1776 break;
1777 default:
1778 return FALSE;
1781 start_sequence ();
1783 target = expand_abs_nojump (GET_MODE (if_info->x), b, if_info->x, 1);
1785 /* ??? It's a quandary whether cmove would be better here, especially
1786 for integers. Perhaps combine will clean things up. */
1787 if (target && negate)
1788 target = expand_simple_unop (GET_MODE (target), NEG, target, if_info->x, 0);
1790 if (! target)
1792 end_sequence ();
1793 return FALSE;
1796 if (target != if_info->x)
1797 noce_emit_move_insn (if_info->x, target);
1799 seq = end_ifcvt_sequence (if_info);
1800 if (!seq)
1801 return FALSE;
1803 emit_insn_before_setloc (seq, if_info->jump, INSN_LOCATOR (if_info->insn_a));
1804 if_info->cond = cond;
1805 if_info->cond_earliest = earliest;
1807 return TRUE;
1810 /* Convert "if (m < 0) x = b; else x = 0;" to "x = (m >> C) & b;". */
1812 static int
1813 noce_try_sign_mask (struct noce_if_info *if_info)
1815 rtx cond, t, m, c, seq;
1816 enum machine_mode mode;
1817 enum rtx_code code;
1819 if (no_new_pseudos)
1820 return FALSE;
1822 cond = if_info->cond;
1823 code = GET_CODE (cond);
1824 m = XEXP (cond, 0);
1825 c = XEXP (cond, 1);
1827 t = NULL_RTX;
1828 if (if_info->a == const0_rtx)
1830 if ((code == LT && c == const0_rtx)
1831 || (code == LE && c == constm1_rtx))
1832 t = if_info->b;
1834 else if (if_info->b == const0_rtx)
1836 if ((code == GE && c == const0_rtx)
1837 || (code == GT && c == constm1_rtx))
1838 t = if_info->a;
1841 if (! t || side_effects_p (t))
1842 return FALSE;
1844 /* We currently don't handle different modes. */
1845 mode = GET_MODE (t);
1846 if (GET_MODE (m) != mode)
1847 return FALSE;
1849 /* This is only profitable if T is cheap, or T is unconditionally
1850 executed/evaluated in the original insn sequence. */
1851 if (rtx_cost (t, SET) >= COSTS_N_INSNS (2)
1852 && (!if_info->b_unconditional
1853 || t != if_info->b))
1854 return FALSE;
1856 start_sequence ();
1857 /* Use emit_store_flag to generate "m < 0 ? -1 : 0" instead of expanding
1858 "(signed) m >> 31" directly. This benefits targets with specialized
1859 insns to obtain the signmask, but still uses ashr_optab otherwise. */
1860 m = emit_store_flag (gen_reg_rtx (mode), LT, m, const0_rtx, mode, 0, -1);
1861 t = m ? expand_binop (mode, and_optab, m, t, NULL_RTX, 0, OPTAB_DIRECT)
1862 : NULL_RTX;
1864 if (!t)
1866 end_sequence ();
1867 return FALSE;
1870 noce_emit_move_insn (if_info->x, t);
1872 seq = end_ifcvt_sequence (if_info);
1873 if (!seq)
1874 return FALSE;
1876 emit_insn_before_setloc (seq, if_info->jump, INSN_LOCATOR (if_info->insn_a));
1877 return TRUE;
1881 /* Optimize away "if (x & C) x |= C" and similar bit manipulation
1882 transformations. */
1884 static int
1885 noce_try_bitop (struct noce_if_info *if_info)
1887 rtx cond, x, a, result, seq;
1888 enum machine_mode mode;
1889 enum rtx_code code;
1890 int bitnum;
1892 x = if_info->x;
1893 cond = if_info->cond;
1894 code = GET_CODE (cond);
1896 /* Check for no else condition. */
1897 if (! rtx_equal_p (x, if_info->b))
1898 return FALSE;
1900 /* Check for a suitable condition. */
1901 if (code != NE && code != EQ)
1902 return FALSE;
1903 if (XEXP (cond, 1) != const0_rtx)
1904 return FALSE;
1905 cond = XEXP (cond, 0);
1907 /* ??? We could also handle AND here. */
1908 if (GET_CODE (cond) == ZERO_EXTRACT)
1910 if (XEXP (cond, 1) != const1_rtx
1911 || GET_CODE (XEXP (cond, 2)) != CONST_INT
1912 || ! rtx_equal_p (x, XEXP (cond, 0)))
1913 return FALSE;
1914 bitnum = INTVAL (XEXP (cond, 2));
1915 mode = GET_MODE (x);
1916 if (bitnum >= HOST_BITS_PER_WIDE_INT)
1917 return FALSE;
1919 else
1920 return FALSE;
1922 a = if_info->a;
1923 if (GET_CODE (a) == IOR || GET_CODE (a) == XOR)
1925 /* Check for "if (X & C) x = x op C". */
1926 if (! rtx_equal_p (x, XEXP (a, 0))
1927 || GET_CODE (XEXP (a, 1)) != CONST_INT
1928 || (INTVAL (XEXP (a, 1)) & GET_MODE_MASK (mode))
1929 != (unsigned HOST_WIDE_INT) 1 << bitnum)
1930 return FALSE;
1932 /* if ((x & C) == 0) x |= C; is transformed to x |= C. */
1933 /* if ((x & C) != 0) x |= C; is transformed to nothing. */
1934 if (GET_CODE (a) == IOR)
1935 result = (code == NE) ? a : NULL_RTX;
1936 else if (code == NE)
1938 /* if ((x & C) == 0) x ^= C; is transformed to x |= C. */
1939 result = gen_int_mode ((HOST_WIDE_INT) 1 << bitnum, mode);
1940 result = simplify_gen_binary (IOR, mode, x, result);
1942 else
1944 /* if ((x & C) != 0) x ^= C; is transformed to x &= ~C. */
1945 result = gen_int_mode (~((HOST_WIDE_INT) 1 << bitnum), mode);
1946 result = simplify_gen_binary (AND, mode, x, result);
1949 else if (GET_CODE (a) == AND)
1951 /* Check for "if (X & C) x &= ~C". */
1952 if (! rtx_equal_p (x, XEXP (a, 0))
1953 || GET_CODE (XEXP (a, 1)) != CONST_INT
1954 || (INTVAL (XEXP (a, 1)) & GET_MODE_MASK (mode))
1955 != (~((HOST_WIDE_INT) 1 << bitnum) & GET_MODE_MASK (mode)))
1956 return FALSE;
1958 /* if ((x & C) == 0) x &= ~C; is transformed to nothing. */
1959 /* if ((x & C) != 0) x &= ~C; is transformed to x &= ~C. */
1960 result = (code == EQ) ? a : NULL_RTX;
1962 else
1963 return FALSE;
1965 if (result)
1967 start_sequence ();
1968 noce_emit_move_insn (x, result);
1969 seq = end_ifcvt_sequence (if_info);
1970 if (!seq)
1971 return FALSE;
1973 emit_insn_before_setloc (seq, if_info->jump,
1974 INSN_LOCATOR (if_info->insn_a));
1976 return TRUE;
1980 /* Similar to get_condition, only the resulting condition must be
1981 valid at JUMP, instead of at EARLIEST. */
1983 static rtx
1984 noce_get_condition (rtx jump, rtx *earliest)
1986 rtx cond, set, tmp;
1987 bool reverse;
1989 if (! any_condjump_p (jump))
1990 return NULL_RTX;
1992 set = pc_set (jump);
1994 /* If this branches to JUMP_LABEL when the condition is false,
1995 reverse the condition. */
1996 reverse = (GET_CODE (XEXP (SET_SRC (set), 2)) == LABEL_REF
1997 && XEXP (XEXP (SET_SRC (set), 2), 0) == JUMP_LABEL (jump));
1999 /* If the condition variable is a register and is MODE_INT, accept it. */
2001 cond = XEXP (SET_SRC (set), 0);
2002 tmp = XEXP (cond, 0);
2003 if (REG_P (tmp) && GET_MODE_CLASS (GET_MODE (tmp)) == MODE_INT)
2005 *earliest = jump;
2007 if (reverse)
2008 cond = gen_rtx_fmt_ee (reverse_condition (GET_CODE (cond)),
2009 GET_MODE (cond), tmp, XEXP (cond, 1));
2010 return cond;
2013 /* Otherwise, fall back on canonicalize_condition to do the dirty
2014 work of manipulating MODE_CC values and COMPARE rtx codes. */
2015 return canonicalize_condition (jump, cond, reverse, earliest,
2016 NULL_RTX, false, true);
2019 /* Initialize for a simple IF-THEN or IF-THEN-ELSE block. We will not
2020 be using conditional execution. Set some fields of IF_INFO based
2021 on CE_INFO: test_bb, cond, jump, cond_earliest. Return TRUE if
2022 things look OK. */
2024 static int
2025 noce_init_if_info (struct ce_if_block *ce_info, struct noce_if_info *if_info)
2027 basic_block test_bb = ce_info->test_bb;
2028 rtx cond, jump;
2030 /* If test is comprised of && or || elements, don't handle it unless
2031 it is the special case of && elements without an ELSE block. */
2032 if (ce_info->num_multiple_test_blocks)
2034 if (ce_info->else_bb || !ce_info->and_and_p)
2035 return FALSE;
2037 ce_info->test_bb = test_bb = ce_info->last_test_bb;
2038 ce_info->num_multiple_test_blocks = 0;
2039 ce_info->num_and_and_blocks = 0;
2040 ce_info->num_or_or_blocks = 0;
2043 /* If this is not a standard conditional jump, we can't parse it. */
2044 jump = BB_END (test_bb);
2045 cond = noce_get_condition (jump, &if_info->cond_earliest);
2046 if (!cond)
2047 return FALSE;
2049 /* If the conditional jump is more than just a conditional
2050 jump, then we can not do if-conversion on this block. */
2051 if (! onlyjump_p (jump))
2052 return FALSE;
2054 /* We must be comparing objects whose modes imply the size. */
2055 if (GET_MODE (XEXP (cond, 0)) == BLKmode)
2056 return FALSE;
2058 if_info->test_bb = test_bb;
2059 if_info->cond = cond;
2060 if_info->jump = jump;
2062 return TRUE;
2065 /* Return true if OP is ok for if-then-else processing. */
2067 static int
2068 noce_operand_ok (rtx op)
2070 /* We special-case memories, so handle any of them with
2071 no address side effects. */
2072 if (MEM_P (op))
2073 return ! side_effects_p (XEXP (op, 0));
2075 if (side_effects_p (op))
2076 return FALSE;
2078 return ! may_trap_p (op);
2081 /* Return true if a write into MEM may trap or fault. */
2083 static bool
2084 noce_mem_write_may_trap_or_fault_p (rtx mem)
2086 rtx addr;
2088 if (MEM_READONLY_P (mem))
2089 return true;
2091 if (may_trap_or_fault_p (mem))
2092 return true;
2094 addr = XEXP (mem, 0);
2096 /* Call target hook to avoid the effects of -fpic etc.... */
2097 addr = targetm.delegitimize_address (addr);
2099 while (addr)
2100 switch (GET_CODE (addr))
2102 case CONST:
2103 case PRE_DEC:
2104 case PRE_INC:
2105 case POST_DEC:
2106 case POST_INC:
2107 case POST_MODIFY:
2108 addr = XEXP (addr, 0);
2109 break;
2110 case LO_SUM:
2111 case PRE_MODIFY:
2112 addr = XEXP (addr, 1);
2113 break;
2114 case PLUS:
2115 if (GET_CODE (XEXP (addr, 1)) == CONST_INT)
2116 addr = XEXP (addr, 0);
2117 else
2118 return false;
2119 break;
2120 case LABEL_REF:
2121 return true;
2122 case SYMBOL_REF:
2123 if (SYMBOL_REF_DECL (addr)
2124 && decl_readonly_section (SYMBOL_REF_DECL (addr), 0))
2125 return true;
2126 return false;
2127 default:
2128 return false;
2131 return false;
2134 /* Given a simple IF-THEN or IF-THEN-ELSE block, attempt to convert it
2135 without using conditional execution. Return TRUE if we were
2136 successful at converting the block. */
2138 static int
2139 noce_process_if_block (struct ce_if_block * ce_info)
2141 basic_block test_bb = ce_info->test_bb; /* test block */
2142 basic_block then_bb = ce_info->then_bb; /* THEN */
2143 basic_block else_bb = ce_info->else_bb; /* ELSE or NULL */
2144 struct noce_if_info if_info;
2145 rtx insn_a, insn_b;
2146 rtx set_a, set_b;
2147 rtx orig_x, x, a, b;
2148 rtx jump, cond;
2150 /* We're looking for patterns of the form
2152 (1) if (...) x = a; else x = b;
2153 (2) x = b; if (...) x = a;
2154 (3) if (...) x = a; // as if with an initial x = x.
2156 The later patterns require jumps to be more expensive.
2158 ??? For future expansion, look for multiple X in such patterns. */
2160 if (!noce_init_if_info (ce_info, &if_info))
2161 return FALSE;
2163 cond = if_info.cond;
2164 jump = if_info.jump;
2166 /* Look for one of the potential sets. */
2167 insn_a = first_active_insn (then_bb);
2168 if (! insn_a
2169 || insn_a != last_active_insn (then_bb, FALSE)
2170 || (set_a = single_set (insn_a)) == NULL_RTX)
2171 return FALSE;
2173 x = SET_DEST (set_a);
2174 a = SET_SRC (set_a);
2176 /* Look for the other potential set. Make sure we've got equivalent
2177 destinations. */
2178 /* ??? This is overconservative. Storing to two different mems is
2179 as easy as conditionally computing the address. Storing to a
2180 single mem merely requires a scratch memory to use as one of the
2181 destination addresses; often the memory immediately below the
2182 stack pointer is available for this. */
2183 set_b = NULL_RTX;
2184 if (else_bb)
2186 insn_b = first_active_insn (else_bb);
2187 if (! insn_b
2188 || insn_b != last_active_insn (else_bb, FALSE)
2189 || (set_b = single_set (insn_b)) == NULL_RTX
2190 || ! rtx_equal_p (x, SET_DEST (set_b)))
2191 return FALSE;
2193 else
2195 insn_b = prev_nonnote_insn (if_info.cond_earliest);
2196 /* We're going to be moving the evaluation of B down from above
2197 COND_EARLIEST to JUMP. Make sure the relevant data is still
2198 intact. */
2199 if (! insn_b
2200 || !NONJUMP_INSN_P (insn_b)
2201 || (set_b = single_set (insn_b)) == NULL_RTX
2202 || ! rtx_equal_p (x, SET_DEST (set_b))
2203 || reg_overlap_mentioned_p (x, SET_SRC (set_b))
2204 || modified_between_p (SET_SRC (set_b),
2205 PREV_INSN (if_info.cond_earliest), jump)
2206 /* Likewise with X. In particular this can happen when
2207 noce_get_condition looks farther back in the instruction
2208 stream than one might expect. */
2209 || reg_overlap_mentioned_p (x, cond)
2210 || reg_overlap_mentioned_p (x, a)
2211 || modified_between_p (x, PREV_INSN (if_info.cond_earliest), jump))
2212 insn_b = set_b = NULL_RTX;
2215 /* If x has side effects then only the if-then-else form is safe to
2216 convert. But even in that case we would need to restore any notes
2217 (such as REG_INC) at then end. That can be tricky if
2218 noce_emit_move_insn expands to more than one insn, so disable the
2219 optimization entirely for now if there are side effects. */
2220 if (side_effects_p (x))
2221 return FALSE;
2223 b = (set_b ? SET_SRC (set_b) : x);
2225 /* Only operate on register destinations, and even then avoid extending
2226 the lifetime of hard registers on small register class machines. */
2227 orig_x = x;
2228 if (!REG_P (x)
2229 || (SMALL_REGISTER_CLASSES
2230 && REGNO (x) < FIRST_PSEUDO_REGISTER))
2232 if (no_new_pseudos || GET_MODE (x) == BLKmode)
2233 return FALSE;
2234 x = gen_reg_rtx (GET_MODE (GET_CODE (x) == STRICT_LOW_PART
2235 ? XEXP (x, 0) : x));
2238 /* Don't operate on sources that may trap or are volatile. */
2239 if (! noce_operand_ok (a) || ! noce_operand_ok (b))
2240 return FALSE;
2242 /* Set up the info block for our subroutines. */
2243 if_info.insn_a = insn_a;
2244 if_info.insn_b = insn_b;
2245 if_info.x = x;
2246 if_info.a = a;
2247 if_info.b = b;
2248 if_info.b_unconditional = else_bb == 0;
2250 /* Try optimizations in some approximation of a useful order. */
2251 /* ??? Should first look to see if X is live incoming at all. If it
2252 isn't, we don't need anything but an unconditional set. */
2254 /* Look and see if A and B are really the same. Avoid creating silly
2255 cmove constructs that no one will fix up later. */
2256 if (rtx_equal_p (a, b))
2258 /* If we have an INSN_B, we don't have to create any new rtl. Just
2259 move the instruction that we already have. If we don't have an
2260 INSN_B, that means that A == X, and we've got a noop move. In
2261 that case don't do anything and let the code below delete INSN_A. */
2262 if (insn_b && else_bb)
2264 rtx note;
2266 if (else_bb && insn_b == BB_END (else_bb))
2267 BB_END (else_bb) = PREV_INSN (insn_b);
2268 reorder_insns (insn_b, insn_b, PREV_INSN (jump));
2270 /* If there was a REG_EQUAL note, delete it since it may have been
2271 true due to this insn being after a jump. */
2272 if ((note = find_reg_note (insn_b, REG_EQUAL, NULL_RTX)) != 0)
2273 remove_note (insn_b, note);
2275 insn_b = NULL_RTX;
2277 /* If we have "x = b; if (...) x = a;", and x has side-effects, then
2278 x must be executed twice. */
2279 else if (insn_b && side_effects_p (orig_x))
2280 return FALSE;
2282 x = orig_x;
2283 goto success;
2286 /* Disallow the "if (...) x = a;" form (with an implicit "else x = x;")
2287 for optimizations if writing to x may trap or fault, i.e. it's a memory
2288 other than a static var or a stack slot, is misaligned on strict
2289 aligned machines or is read-only.
2290 If x is a read-only memory, then the program is valid only if we
2291 avoid the store into it. If there are stores on both the THEN and
2292 ELSE arms, then we can go ahead with the conversion; either the
2293 program is broken, or the condition is always false such that the
2294 other memory is selected. */
2295 if (!set_b && MEM_P (orig_x) && noce_mem_write_may_trap_or_fault_p (orig_x))
2296 return FALSE;
2298 if (noce_try_move (&if_info))
2299 goto success;
2300 if (noce_try_store_flag (&if_info))
2301 goto success;
2302 if (noce_try_bitop (&if_info))
2303 goto success;
2304 if (noce_try_minmax (&if_info))
2305 goto success;
2306 if (noce_try_abs (&if_info))
2307 goto success;
2308 if (HAVE_conditional_move
2309 && noce_try_cmove (&if_info))
2310 goto success;
2311 if (! HAVE_conditional_execution)
2313 if (noce_try_store_flag_constants (&if_info))
2314 goto success;
2315 if (noce_try_addcc (&if_info))
2316 goto success;
2317 if (noce_try_store_flag_mask (&if_info))
2318 goto success;
2319 if (HAVE_conditional_move
2320 && noce_try_cmove_arith (&if_info))
2321 goto success;
2322 if (noce_try_sign_mask (&if_info))
2323 goto success;
2326 return FALSE;
2328 success:
2329 /* The original sets may now be killed. */
2330 delete_insn (insn_a);
2332 /* Several special cases here: First, we may have reused insn_b above,
2333 in which case insn_b is now NULL. Second, we want to delete insn_b
2334 if it came from the ELSE block, because follows the now correct
2335 write that appears in the TEST block. However, if we got insn_b from
2336 the TEST block, it may in fact be loading data needed for the comparison.
2337 We'll let life_analysis remove the insn if it's really dead. */
2338 if (insn_b && else_bb)
2339 delete_insn (insn_b);
2341 /* The new insns will have been inserted immediately before the jump. We
2342 should be able to remove the jump with impunity, but the condition itself
2343 may have been modified by gcse to be shared across basic blocks. */
2344 delete_insn (jump);
2346 /* If we used a temporary, fix it up now. */
2347 if (orig_x != x)
2349 start_sequence ();
2350 noce_emit_move_insn (orig_x, x);
2351 insn_b = get_insns ();
2352 set_used_flags (orig_x);
2353 unshare_all_rtl_in_chain (insn_b);
2354 end_sequence ();
2356 emit_insn_after_setloc (insn_b, BB_END (test_bb), INSN_LOCATOR (insn_a));
2359 /* Merge the blocks! */
2360 merge_if_block (ce_info);
2362 return TRUE;
2365 /* Check whether a block is suitable for conditional move conversion.
2366 Every insn must be a simple set of a register to a constant or a
2367 register. For each assignment, store the value in the array VALS,
2368 indexed by register number. COND is the condition we will
2369 test. */
2371 static int
2372 check_cond_move_block (basic_block bb, rtx *vals, rtx cond)
2374 rtx insn;
2376 FOR_BB_INSNS (bb, insn)
2378 rtx set, dest, src;
2380 if (!INSN_P (insn) || JUMP_P (insn))
2381 continue;
2382 set = single_set (insn);
2383 if (!set)
2384 return FALSE;
2386 dest = SET_DEST (set);
2387 src = SET_SRC (set);
2388 if (!REG_P (dest)
2389 || (SMALL_REGISTER_CLASSES && HARD_REGISTER_P (dest)))
2390 return false;
2392 if (!CONSTANT_P (src) && !register_operand (src, VOIDmode))
2393 return FALSE;
2395 if (side_effects_p (src) || side_effects_p (dest))
2396 return FALSE;
2398 if (may_trap_p (src) || may_trap_p (dest))
2399 return FALSE;
2401 /* Don't try to handle this if the destination register was
2402 modified earlier in the block. */
2403 if (vals[REGNO (dest)] != NULL)
2404 return FALSE;
2406 /* Don't try to handle this if the condition uses the
2407 destination register. */
2408 if (reg_overlap_mentioned_p (dest, cond))
2409 return FALSE;
2411 vals[REGNO (dest)] = src;
2413 /* Don't try to handle this if the source register is modified
2414 later in the block. */
2415 if (!CONSTANT_P (src)
2416 && modified_between_p (src, insn, NEXT_INSN (BB_END (bb))))
2417 return FALSE;
2420 return TRUE;
2423 /* Given a simple IF-THEN or IF-THEN-ELSE block, attempt to convert it
2424 using only conditional moves. Return TRUE if we were successful at
2425 converting the block. */
2427 static int
2428 cond_move_process_if_block (struct ce_if_block *ce_info)
2430 basic_block then_bb = ce_info->then_bb;
2431 basic_block else_bb = ce_info->else_bb;
2432 struct noce_if_info if_info;
2433 rtx jump, cond, insn, seq, cond_arg0, cond_arg1, loc_insn;
2434 int max_reg, size, c, i;
2435 rtx *then_vals;
2436 rtx *else_vals;
2437 enum rtx_code code;
2439 if (!HAVE_conditional_move || no_new_pseudos)
2440 return FALSE;
2442 memset (&if_info, 0, sizeof if_info);
2444 if (!noce_init_if_info (ce_info, &if_info))
2445 return FALSE;
2447 cond = if_info.cond;
2448 jump = if_info.jump;
2450 /* Build a mapping for each block to the value used for each
2451 register. */
2452 max_reg = max_reg_num ();
2453 size = (max_reg + 1) * sizeof (rtx);
2454 then_vals = (rtx *) alloca (size);
2455 else_vals = (rtx *) alloca (size);
2456 memset (then_vals, 0, size);
2457 memset (else_vals, 0, size);
2459 /* Make sure the blocks are suitable. */
2460 if (!check_cond_move_block (then_bb, then_vals, cond)
2461 || (else_bb && !check_cond_move_block (else_bb, else_vals, cond)))
2462 return FALSE;
2464 /* Make sure the blocks can be used together. If the same register
2465 is set in both blocks, and is not set to a constant in both
2466 cases, then both blocks must set it to the same register. We
2467 have already verified that if it is set to a register, that the
2468 source register does not change after the assignment. Also count
2469 the number of registers set in only one of the blocks. */
2470 c = 0;
2471 for (i = 0; i <= max_reg; ++i)
2473 if (!then_vals[i] && !else_vals[i])
2474 continue;
2476 if (!then_vals[i] || !else_vals[i])
2477 ++c;
2478 else
2480 if (!CONSTANT_P (then_vals[i])
2481 && !CONSTANT_P (else_vals[i])
2482 && !rtx_equal_p (then_vals[i], else_vals[i]))
2483 return FALSE;
2487 /* Make sure it is reasonable to convert this block. What matters
2488 is the number of assignments currently made in only one of the
2489 branches, since if we convert we are going to always execute
2490 them. */
2491 if (c > MAX_CONDITIONAL_EXECUTE)
2492 return FALSE;
2494 /* Emit the conditional moves. First do the then block, then do
2495 anything left in the else blocks. */
2497 code = GET_CODE (cond);
2498 cond_arg0 = XEXP (cond, 0);
2499 cond_arg1 = XEXP (cond, 1);
2501 start_sequence ();
2503 FOR_BB_INSNS (then_bb, insn)
2505 rtx set, target, dest, t, e;
2506 unsigned int regno;
2508 if (!INSN_P (insn) || JUMP_P (insn))
2509 continue;
2510 set = single_set (insn);
2511 gcc_assert (set && REG_P (SET_DEST (set)));
2513 dest = SET_DEST (set);
2514 regno = REGNO (dest);
2515 t = then_vals[regno];
2516 e = else_vals[regno];
2517 gcc_assert (t);
2518 if (!e)
2519 e = dest;
2520 target = noce_emit_cmove (&if_info, dest, code, cond_arg0, cond_arg1,
2521 t, e);
2522 if (!target)
2524 end_sequence ();
2525 return FALSE;
2528 if (target != dest)
2529 noce_emit_move_insn (dest, target);
2532 if (else_bb)
2534 FOR_BB_INSNS (else_bb, insn)
2536 rtx set, target, dest;
2537 unsigned int regno;
2539 if (!INSN_P (insn) || JUMP_P (insn))
2540 continue;
2541 set = single_set (insn);
2542 gcc_assert (set && REG_P (SET_DEST (set)));
2544 dest = SET_DEST (set);
2545 regno = REGNO (dest);
2547 /* If this register was set in the then block, we already
2548 handled this case above. */
2549 if (then_vals[regno])
2550 continue;
2551 gcc_assert (else_vals[regno]);
2553 target = noce_emit_cmove (&if_info, dest, code, cond_arg0, cond_arg1,
2554 dest, else_vals[regno]);
2555 if (!target)
2557 end_sequence ();
2558 return FALSE;
2561 if (target != dest)
2562 noce_emit_move_insn (dest, target);
2566 seq = end_ifcvt_sequence (&if_info);
2567 if (!seq)
2568 return FALSE;
2570 loc_insn = first_active_insn (then_bb);
2571 if (!loc_insn)
2573 loc_insn = first_active_insn (else_bb);
2574 gcc_assert (loc_insn);
2576 emit_insn_before_setloc (seq, jump, INSN_LOCATOR (loc_insn));
2578 FOR_BB_INSNS (then_bb, insn)
2579 if (INSN_P (insn) && !JUMP_P (insn))
2580 delete_insn (insn);
2581 if (else_bb)
2583 FOR_BB_INSNS (else_bb, insn)
2584 if (INSN_P (insn) && !JUMP_P (insn))
2585 delete_insn (insn);
2587 delete_insn (jump);
2589 merge_if_block (ce_info);
2591 return TRUE;
2594 /* Attempt to convert an IF-THEN or IF-THEN-ELSE block into
2595 straight line code. Return true if successful. */
2597 static int
2598 process_if_block (struct ce_if_block * ce_info)
2600 if (! reload_completed
2601 && noce_process_if_block (ce_info))
2602 return TRUE;
2604 if (HAVE_conditional_move
2605 && cond_move_process_if_block (ce_info))
2606 return TRUE;
2608 if (HAVE_conditional_execution && reload_completed)
2610 /* If we have && and || tests, try to first handle combining the && and
2611 || tests into the conditional code, and if that fails, go back and
2612 handle it without the && and ||, which at present handles the && case
2613 if there was no ELSE block. */
2614 if (cond_exec_process_if_block (ce_info, TRUE))
2615 return TRUE;
2617 if (ce_info->num_multiple_test_blocks)
2619 cancel_changes (0);
2621 if (cond_exec_process_if_block (ce_info, FALSE))
2622 return TRUE;
2626 return FALSE;
2629 /* Merge the blocks and mark for local life update. */
2631 static void
2632 merge_if_block (struct ce_if_block * ce_info)
2634 basic_block test_bb = ce_info->test_bb; /* last test block */
2635 basic_block then_bb = ce_info->then_bb; /* THEN */
2636 basic_block else_bb = ce_info->else_bb; /* ELSE or NULL */
2637 basic_block join_bb = ce_info->join_bb; /* join block */
2638 basic_block combo_bb;
2640 /* All block merging is done into the lower block numbers. */
2642 combo_bb = test_bb;
2644 /* Merge any basic blocks to handle && and || subtests. Each of
2645 the blocks are on the fallthru path from the predecessor block. */
2646 if (ce_info->num_multiple_test_blocks > 0)
2648 basic_block bb = test_bb;
2649 basic_block last_test_bb = ce_info->last_test_bb;
2650 basic_block fallthru = block_fallthru (bb);
2654 bb = fallthru;
2655 fallthru = block_fallthru (bb);
2656 merge_blocks (combo_bb, bb);
2657 num_true_changes++;
2659 while (bb != last_test_bb);
2662 /* Merge TEST block into THEN block. Normally the THEN block won't have a
2663 label, but it might if there were || tests. That label's count should be
2664 zero, and it normally should be removed. */
2666 if (then_bb)
2668 if (combo_bb->il.rtl->global_live_at_end)
2669 COPY_REG_SET (combo_bb->il.rtl->global_live_at_end,
2670 then_bb->il.rtl->global_live_at_end);
2671 merge_blocks (combo_bb, then_bb);
2672 num_true_changes++;
2675 /* The ELSE block, if it existed, had a label. That label count
2676 will almost always be zero, but odd things can happen when labels
2677 get their addresses taken. */
2678 if (else_bb)
2680 merge_blocks (combo_bb, else_bb);
2681 num_true_changes++;
2684 /* If there was no join block reported, that means it was not adjacent
2685 to the others, and so we cannot merge them. */
2687 if (! join_bb)
2689 rtx last = BB_END (combo_bb);
2691 /* The outgoing edge for the current COMBO block should already
2692 be correct. Verify this. */
2693 if (EDGE_COUNT (combo_bb->succs) == 0)
2694 gcc_assert (find_reg_note (last, REG_NORETURN, NULL)
2695 || (NONJUMP_INSN_P (last)
2696 && GET_CODE (PATTERN (last)) == TRAP_IF
2697 && (TRAP_CONDITION (PATTERN (last))
2698 == const_true_rtx)));
2700 else
2701 /* There should still be something at the end of the THEN or ELSE
2702 blocks taking us to our final destination. */
2703 gcc_assert (JUMP_P (last)
2704 || (EDGE_SUCC (combo_bb, 0)->dest == EXIT_BLOCK_PTR
2705 && CALL_P (last)
2706 && SIBLING_CALL_P (last))
2707 || ((EDGE_SUCC (combo_bb, 0)->flags & EDGE_EH)
2708 && can_throw_internal (last)));
2711 /* The JOIN block may have had quite a number of other predecessors too.
2712 Since we've already merged the TEST, THEN and ELSE blocks, we should
2713 have only one remaining edge from our if-then-else diamond. If there
2714 is more than one remaining edge, it must come from elsewhere. There
2715 may be zero incoming edges if the THEN block didn't actually join
2716 back up (as with a call to a non-return function). */
2717 else if (EDGE_COUNT (join_bb->preds) < 2
2718 && join_bb != EXIT_BLOCK_PTR)
2720 /* We can merge the JOIN. */
2721 if (combo_bb->il.rtl->global_live_at_end)
2722 COPY_REG_SET (combo_bb->il.rtl->global_live_at_end,
2723 join_bb->il.rtl->global_live_at_end);
2725 merge_blocks (combo_bb, join_bb);
2726 num_true_changes++;
2728 else
2730 /* We cannot merge the JOIN. */
2732 /* The outgoing edge for the current COMBO block should already
2733 be correct. Verify this. */
2734 gcc_assert (single_succ_p (combo_bb)
2735 && single_succ (combo_bb) == join_bb);
2737 /* Remove the jump and cruft from the end of the COMBO block. */
2738 if (join_bb != EXIT_BLOCK_PTR)
2739 tidy_fallthru_edge (single_succ_edge (combo_bb));
2742 num_updated_if_blocks++;
2745 /* Find a block ending in a simple IF condition and try to transform it
2746 in some way. When converting a multi-block condition, put the new code
2747 in the first such block and delete the rest. Return a pointer to this
2748 first block if some transformation was done. Return NULL otherwise. */
2750 static basic_block
2751 find_if_header (basic_block test_bb, int pass)
2753 ce_if_block_t ce_info;
2754 edge then_edge;
2755 edge else_edge;
2757 /* The kind of block we're looking for has exactly two successors. */
2758 if (EDGE_COUNT (test_bb->succs) != 2)
2759 return NULL;
2761 then_edge = EDGE_SUCC (test_bb, 0);
2762 else_edge = EDGE_SUCC (test_bb, 1);
2764 /* Neither edge should be abnormal. */
2765 if ((then_edge->flags & EDGE_COMPLEX)
2766 || (else_edge->flags & EDGE_COMPLEX))
2767 return NULL;
2769 /* Nor exit the loop. */
2770 if ((then_edge->flags & EDGE_LOOP_EXIT)
2771 || (else_edge->flags & EDGE_LOOP_EXIT))
2772 return NULL;
2774 /* The THEN edge is canonically the one that falls through. */
2775 if (then_edge->flags & EDGE_FALLTHRU)
2777 else if (else_edge->flags & EDGE_FALLTHRU)
2779 edge e = else_edge;
2780 else_edge = then_edge;
2781 then_edge = e;
2783 else
2784 /* Otherwise this must be a multiway branch of some sort. */
2785 return NULL;
2787 memset (&ce_info, '\0', sizeof (ce_info));
2788 ce_info.test_bb = test_bb;
2789 ce_info.then_bb = then_edge->dest;
2790 ce_info.else_bb = else_edge->dest;
2791 ce_info.pass = pass;
2793 #ifdef IFCVT_INIT_EXTRA_FIELDS
2794 IFCVT_INIT_EXTRA_FIELDS (&ce_info);
2795 #endif
2797 if (find_if_block (&ce_info))
2798 goto success;
2800 if (HAVE_trap && HAVE_conditional_trap
2801 && find_cond_trap (test_bb, then_edge, else_edge))
2802 goto success;
2804 if (dom_computed[CDI_POST_DOMINATORS] >= DOM_NO_FAST_QUERY
2805 && (! HAVE_conditional_execution || reload_completed))
2807 if (find_if_case_1 (test_bb, then_edge, else_edge))
2808 goto success;
2809 if (find_if_case_2 (test_bb, then_edge, else_edge))
2810 goto success;
2813 return NULL;
2815 success:
2816 if (dump_file)
2817 fprintf (dump_file, "Conversion succeeded on pass %d.\n", pass);
2818 return ce_info.test_bb;
2821 /* Return true if a block has two edges, one of which falls through to the next
2822 block, and the other jumps to a specific block, so that we can tell if the
2823 block is part of an && test or an || test. Returns either -1 or the number
2824 of non-note, non-jump, non-USE/CLOBBER insns in the block. */
2826 static int
2827 block_jumps_and_fallthru_p (basic_block cur_bb, basic_block target_bb)
2829 edge cur_edge;
2830 int fallthru_p = FALSE;
2831 int jump_p = FALSE;
2832 rtx insn;
2833 rtx end;
2834 int n_insns = 0;
2835 edge_iterator ei;
2837 if (!cur_bb || !target_bb)
2838 return -1;
2840 /* If no edges, obviously it doesn't jump or fallthru. */
2841 if (EDGE_COUNT (cur_bb->succs) == 0)
2842 return FALSE;
2844 FOR_EACH_EDGE (cur_edge, ei, cur_bb->succs)
2846 if (cur_edge->flags & EDGE_COMPLEX)
2847 /* Anything complex isn't what we want. */
2848 return -1;
2850 else if (cur_edge->flags & EDGE_FALLTHRU)
2851 fallthru_p = TRUE;
2853 else if (cur_edge->dest == target_bb)
2854 jump_p = TRUE;
2856 else
2857 return -1;
2860 if ((jump_p & fallthru_p) == 0)
2861 return -1;
2863 /* Don't allow calls in the block, since this is used to group && and ||
2864 together for conditional execution support. ??? we should support
2865 conditional execution support across calls for IA-64 some day, but
2866 for now it makes the code simpler. */
2867 end = BB_END (cur_bb);
2868 insn = BB_HEAD (cur_bb);
2870 while (insn != NULL_RTX)
2872 if (CALL_P (insn))
2873 return -1;
2875 if (INSN_P (insn)
2876 && !JUMP_P (insn)
2877 && GET_CODE (PATTERN (insn)) != USE
2878 && GET_CODE (PATTERN (insn)) != CLOBBER)
2879 n_insns++;
2881 if (insn == end)
2882 break;
2884 insn = NEXT_INSN (insn);
2887 return n_insns;
2890 /* Determine if a given basic block heads a simple IF-THEN or IF-THEN-ELSE
2891 block. If so, we'll try to convert the insns to not require the branch.
2892 Return TRUE if we were successful at converting the block. */
2894 static int
2895 find_if_block (struct ce_if_block * ce_info)
2897 basic_block test_bb = ce_info->test_bb;
2898 basic_block then_bb = ce_info->then_bb;
2899 basic_block else_bb = ce_info->else_bb;
2900 basic_block join_bb = NULL_BLOCK;
2901 edge cur_edge;
2902 basic_block next;
2903 edge_iterator ei;
2905 ce_info->last_test_bb = test_bb;
2907 /* Discover if any fall through predecessors of the current test basic block
2908 were && tests (which jump to the else block) or || tests (which jump to
2909 the then block). */
2910 if (HAVE_conditional_execution && reload_completed
2911 && single_pred_p (test_bb)
2912 && single_pred_edge (test_bb)->flags == EDGE_FALLTHRU)
2914 basic_block bb = single_pred (test_bb);
2915 basic_block target_bb;
2916 int max_insns = MAX_CONDITIONAL_EXECUTE;
2917 int n_insns;
2919 /* Determine if the preceding block is an && or || block. */
2920 if ((n_insns = block_jumps_and_fallthru_p (bb, else_bb)) >= 0)
2922 ce_info->and_and_p = TRUE;
2923 target_bb = else_bb;
2925 else if ((n_insns = block_jumps_and_fallthru_p (bb, then_bb)) >= 0)
2927 ce_info->and_and_p = FALSE;
2928 target_bb = then_bb;
2930 else
2931 target_bb = NULL_BLOCK;
2933 if (target_bb && n_insns <= max_insns)
2935 int total_insns = 0;
2936 int blocks = 0;
2938 ce_info->last_test_bb = test_bb;
2940 /* Found at least one && or || block, look for more. */
2943 ce_info->test_bb = test_bb = bb;
2944 total_insns += n_insns;
2945 blocks++;
2947 if (!single_pred_p (bb))
2948 break;
2950 bb = single_pred (bb);
2951 n_insns = block_jumps_and_fallthru_p (bb, target_bb);
2953 while (n_insns >= 0 && (total_insns + n_insns) <= max_insns);
2955 ce_info->num_multiple_test_blocks = blocks;
2956 ce_info->num_multiple_test_insns = total_insns;
2958 if (ce_info->and_and_p)
2959 ce_info->num_and_and_blocks = blocks;
2960 else
2961 ce_info->num_or_or_blocks = blocks;
2965 /* The THEN block of an IF-THEN combo must have exactly one predecessor,
2966 other than any || blocks which jump to the THEN block. */
2967 if ((EDGE_COUNT (then_bb->preds) - ce_info->num_or_or_blocks) != 1)
2968 return FALSE;
2970 /* The edges of the THEN and ELSE blocks cannot have complex edges. */
2971 FOR_EACH_EDGE (cur_edge, ei, then_bb->preds)
2973 if (cur_edge->flags & EDGE_COMPLEX)
2974 return FALSE;
2977 FOR_EACH_EDGE (cur_edge, ei, else_bb->preds)
2979 if (cur_edge->flags & EDGE_COMPLEX)
2980 return FALSE;
2983 /* The THEN block of an IF-THEN combo must have zero or one successors. */
2984 if (EDGE_COUNT (then_bb->succs) > 0
2985 && (!single_succ_p (then_bb)
2986 || (single_succ_edge (then_bb)->flags & EDGE_COMPLEX)
2987 || (flow2_completed && tablejump_p (BB_END (then_bb), NULL, NULL))))
2988 return FALSE;
2990 /* If the THEN block has no successors, conditional execution can still
2991 make a conditional call. Don't do this unless the ELSE block has
2992 only one incoming edge -- the CFG manipulation is too ugly otherwise.
2993 Check for the last insn of the THEN block being an indirect jump, which
2994 is listed as not having any successors, but confuses the rest of the CE
2995 code processing. ??? we should fix this in the future. */
2996 if (EDGE_COUNT (then_bb->succs) == 0)
2998 if (single_pred_p (else_bb))
3000 rtx last_insn = BB_END (then_bb);
3002 while (last_insn
3003 && NOTE_P (last_insn)
3004 && last_insn != BB_HEAD (then_bb))
3005 last_insn = PREV_INSN (last_insn);
3007 if (last_insn
3008 && JUMP_P (last_insn)
3009 && ! simplejump_p (last_insn))
3010 return FALSE;
3012 join_bb = else_bb;
3013 else_bb = NULL_BLOCK;
3015 else
3016 return FALSE;
3019 /* If the THEN block's successor is the other edge out of the TEST block,
3020 then we have an IF-THEN combo without an ELSE. */
3021 else if (single_succ (then_bb) == else_bb)
3023 join_bb = else_bb;
3024 else_bb = NULL_BLOCK;
3027 /* If the THEN and ELSE block meet in a subsequent block, and the ELSE
3028 has exactly one predecessor and one successor, and the outgoing edge
3029 is not complex, then we have an IF-THEN-ELSE combo. */
3030 else if (single_succ_p (else_bb)
3031 && single_succ (then_bb) == single_succ (else_bb)
3032 && single_pred_p (else_bb)
3033 && ! (single_succ_edge (else_bb)->flags & EDGE_COMPLEX)
3034 && ! (flow2_completed && tablejump_p (BB_END (else_bb), NULL, NULL)))
3035 join_bb = single_succ (else_bb);
3037 /* Otherwise it is not an IF-THEN or IF-THEN-ELSE combination. */
3038 else
3039 return FALSE;
3041 num_possible_if_blocks++;
3043 if (dump_file)
3045 fprintf (dump_file,
3046 "\nIF-THEN%s block found, pass %d, start block %d "
3047 "[insn %d], then %d [%d]",
3048 (else_bb) ? "-ELSE" : "",
3049 ce_info->pass,
3050 test_bb->index,
3051 BB_HEAD (test_bb) ? (int)INSN_UID (BB_HEAD (test_bb)) : -1,
3052 then_bb->index,
3053 BB_HEAD (then_bb) ? (int)INSN_UID (BB_HEAD (then_bb)) : -1);
3055 if (else_bb)
3056 fprintf (dump_file, ", else %d [%d]",
3057 else_bb->index,
3058 BB_HEAD (else_bb) ? (int)INSN_UID (BB_HEAD (else_bb)) : -1);
3060 fprintf (dump_file, ", join %d [%d]",
3061 join_bb->index,
3062 BB_HEAD (join_bb) ? (int)INSN_UID (BB_HEAD (join_bb)) : -1);
3064 if (ce_info->num_multiple_test_blocks > 0)
3065 fprintf (dump_file, ", %d %s block%s last test %d [%d]",
3066 ce_info->num_multiple_test_blocks,
3067 (ce_info->and_and_p) ? "&&" : "||",
3068 (ce_info->num_multiple_test_blocks == 1) ? "" : "s",
3069 ce_info->last_test_bb->index,
3070 ((BB_HEAD (ce_info->last_test_bb))
3071 ? (int)INSN_UID (BB_HEAD (ce_info->last_test_bb))
3072 : -1));
3074 fputc ('\n', dump_file);
3077 /* Make sure IF, THEN, and ELSE, blocks are adjacent. Actually, we get the
3078 first condition for free, since we've already asserted that there's a
3079 fallthru edge from IF to THEN. Likewise for the && and || blocks, since
3080 we checked the FALLTHRU flag, those are already adjacent to the last IF
3081 block. */
3082 /* ??? As an enhancement, move the ELSE block. Have to deal with
3083 BLOCK notes, if by no other means than backing out the merge if they
3084 exist. Sticky enough I don't want to think about it now. */
3085 next = then_bb;
3086 if (else_bb && (next = next->next_bb) != else_bb)
3087 return FALSE;
3088 if ((next = next->next_bb) != join_bb && join_bb != EXIT_BLOCK_PTR)
3090 if (else_bb)
3091 join_bb = NULL;
3092 else
3093 return FALSE;
3096 /* Do the real work. */
3097 ce_info->else_bb = else_bb;
3098 ce_info->join_bb = join_bb;
3100 return process_if_block (ce_info);
3103 /* Convert a branch over a trap, or a branch
3104 to a trap, into a conditional trap. */
3106 static int
3107 find_cond_trap (basic_block test_bb, edge then_edge, edge else_edge)
3109 basic_block then_bb = then_edge->dest;
3110 basic_block else_bb = else_edge->dest;
3111 basic_block other_bb, trap_bb;
3112 rtx trap, jump, cond, cond_earliest, seq;
3113 enum rtx_code code;
3115 /* Locate the block with the trap instruction. */
3116 /* ??? While we look for no successors, we really ought to allow
3117 EH successors. Need to fix merge_if_block for that to work. */
3118 if ((trap = block_has_only_trap (then_bb)) != NULL)
3119 trap_bb = then_bb, other_bb = else_bb;
3120 else if ((trap = block_has_only_trap (else_bb)) != NULL)
3121 trap_bb = else_bb, other_bb = then_bb;
3122 else
3123 return FALSE;
3125 if (dump_file)
3127 fprintf (dump_file, "\nTRAP-IF block found, start %d, trap %d\n",
3128 test_bb->index, trap_bb->index);
3131 /* If this is not a standard conditional jump, we can't parse it. */
3132 jump = BB_END (test_bb);
3133 cond = noce_get_condition (jump, &cond_earliest);
3134 if (! cond)
3135 return FALSE;
3137 /* If the conditional jump is more than just a conditional jump, then
3138 we can not do if-conversion on this block. */
3139 if (! onlyjump_p (jump))
3140 return FALSE;
3142 /* We must be comparing objects whose modes imply the size. */
3143 if (GET_MODE (XEXP (cond, 0)) == BLKmode)
3144 return FALSE;
3146 /* Reverse the comparison code, if necessary. */
3147 code = GET_CODE (cond);
3148 if (then_bb == trap_bb)
3150 code = reversed_comparison_code (cond, jump);
3151 if (code == UNKNOWN)
3152 return FALSE;
3155 /* Attempt to generate the conditional trap. */
3156 seq = gen_cond_trap (code, XEXP (cond, 0),
3157 XEXP (cond, 1),
3158 TRAP_CODE (PATTERN (trap)));
3159 if (seq == NULL)
3160 return FALSE;
3162 num_true_changes++;
3164 /* Emit the new insns before cond_earliest. */
3165 emit_insn_before_setloc (seq, cond_earliest, INSN_LOCATOR (trap));
3167 /* Delete the trap block if possible. */
3168 remove_edge (trap_bb == then_bb ? then_edge : else_edge);
3169 if (EDGE_COUNT (trap_bb->preds) == 0)
3170 delete_basic_block (trap_bb);
3172 /* If the non-trap block and the test are now adjacent, merge them.
3173 Otherwise we must insert a direct branch. */
3174 if (test_bb->next_bb == other_bb)
3176 struct ce_if_block new_ce_info;
3177 delete_insn (jump);
3178 memset (&new_ce_info, '\0', sizeof (new_ce_info));
3179 new_ce_info.test_bb = test_bb;
3180 new_ce_info.then_bb = NULL;
3181 new_ce_info.else_bb = NULL;
3182 new_ce_info.join_bb = other_bb;
3183 merge_if_block (&new_ce_info);
3185 else
3187 rtx lab, newjump;
3189 lab = JUMP_LABEL (jump);
3190 newjump = emit_jump_insn_after (gen_jump (lab), jump);
3191 LABEL_NUSES (lab) += 1;
3192 JUMP_LABEL (newjump) = lab;
3193 emit_barrier_after (newjump);
3195 delete_insn (jump);
3198 return TRUE;
3201 /* Subroutine of find_cond_trap: if BB contains only a trap insn,
3202 return it. */
3204 static rtx
3205 block_has_only_trap (basic_block bb)
3207 rtx trap;
3209 /* We're not the exit block. */
3210 if (bb == EXIT_BLOCK_PTR)
3211 return NULL_RTX;
3213 /* The block must have no successors. */
3214 if (EDGE_COUNT (bb->succs) > 0)
3215 return NULL_RTX;
3217 /* The only instruction in the THEN block must be the trap. */
3218 trap = first_active_insn (bb);
3219 if (! (trap == BB_END (bb)
3220 && GET_CODE (PATTERN (trap)) == TRAP_IF
3221 && TRAP_CONDITION (PATTERN (trap)) == const_true_rtx))
3222 return NULL_RTX;
3224 return trap;
3227 /* Look for IF-THEN-ELSE cases in which one of THEN or ELSE is
3228 transformable, but not necessarily the other. There need be no
3229 JOIN block.
3231 Return TRUE if we were successful at converting the block.
3233 Cases we'd like to look at:
3236 if (test) goto over; // x not live
3237 x = a;
3238 goto label;
3239 over:
3241 becomes
3243 x = a;
3244 if (! test) goto label;
3247 if (test) goto E; // x not live
3248 x = big();
3249 goto L;
3251 x = b;
3252 goto M;
3254 becomes
3256 x = b;
3257 if (test) goto M;
3258 x = big();
3259 goto L;
3261 (3) // This one's really only interesting for targets that can do
3262 // multiway branching, e.g. IA-64 BBB bundles. For other targets
3263 // it results in multiple branches on a cache line, which often
3264 // does not sit well with predictors.
3266 if (test1) goto E; // predicted not taken
3267 x = a;
3268 if (test2) goto F;
3271 x = b;
3274 becomes
3276 x = a;
3277 if (test1) goto E;
3278 if (test2) goto F;
3280 Notes:
3282 (A) Don't do (2) if the branch is predicted against the block we're
3283 eliminating. Do it anyway if we can eliminate a branch; this requires
3284 that the sole successor of the eliminated block postdominate the other
3285 side of the if.
3287 (B) With CE, on (3) we can steal from both sides of the if, creating
3289 if (test1) x = a;
3290 if (!test1) x = b;
3291 if (test1) goto J;
3292 if (test2) goto F;
3296 Again, this is most useful if J postdominates.
3298 (C) CE substitutes for helpful life information.
3300 (D) These heuristics need a lot of work. */
3302 /* Tests for case 1 above. */
3304 static int
3305 find_if_case_1 (basic_block test_bb, edge then_edge, edge else_edge)
3307 basic_block then_bb = then_edge->dest;
3308 basic_block else_bb = else_edge->dest, new_bb;
3309 int then_bb_index;
3311 /* If we are partitioning hot/cold basic blocks, we don't want to
3312 mess up unconditional or indirect jumps that cross between hot
3313 and cold sections.
3315 Basic block partitioning may result in some jumps that appear to
3316 be optimizable (or blocks that appear to be mergeable), but which really
3317 must be left untouched (they are required to make it safely across
3318 partition boundaries). See the comments at the top of
3319 bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */
3321 if ((BB_END (then_bb)
3322 && find_reg_note (BB_END (then_bb), REG_CROSSING_JUMP, NULL_RTX))
3323 || (BB_END (test_bb)
3324 && find_reg_note (BB_END (test_bb), REG_CROSSING_JUMP, NULL_RTX))
3325 || (BB_END (else_bb)
3326 && find_reg_note (BB_END (else_bb), REG_CROSSING_JUMP,
3327 NULL_RTX)))
3328 return FALSE;
3330 /* THEN has one successor. */
3331 if (!single_succ_p (then_bb))
3332 return FALSE;
3334 /* THEN does not fall through, but is not strange either. */
3335 if (single_succ_edge (then_bb)->flags & (EDGE_COMPLEX | EDGE_FALLTHRU))
3336 return FALSE;
3338 /* THEN has one predecessor. */
3339 if (!single_pred_p (then_bb))
3340 return FALSE;
3342 /* THEN must do something. */
3343 if (forwarder_block_p (then_bb))
3344 return FALSE;
3346 num_possible_if_blocks++;
3347 if (dump_file)
3348 fprintf (dump_file,
3349 "\nIF-CASE-1 found, start %d, then %d\n",
3350 test_bb->index, then_bb->index);
3352 /* THEN is small. */
3353 if (! cheap_bb_rtx_cost_p (then_bb, COSTS_N_INSNS (BRANCH_COST)))
3354 return FALSE;
3356 /* Registers set are dead, or are predicable. */
3357 if (! dead_or_predicable (test_bb, then_bb, else_bb,
3358 single_succ (then_bb), 1))
3359 return FALSE;
3361 /* Conversion went ok, including moving the insns and fixing up the
3362 jump. Adjust the CFG to match. */
3364 bitmap_ior (test_bb->il.rtl->global_live_at_end,
3365 else_bb->il.rtl->global_live_at_start,
3366 then_bb->il.rtl->global_live_at_end);
3369 /* We can avoid creating a new basic block if then_bb is immediately
3370 followed by else_bb, i.e. deleting then_bb allows test_bb to fall
3371 thru to else_bb. */
3373 if (then_bb->next_bb == else_bb
3374 && then_bb->prev_bb == test_bb
3375 && else_bb != EXIT_BLOCK_PTR)
3377 redirect_edge_succ (FALLTHRU_EDGE (test_bb), else_bb);
3378 new_bb = 0;
3380 else
3381 new_bb = redirect_edge_and_branch_force (FALLTHRU_EDGE (test_bb),
3382 else_bb);
3384 then_bb_index = then_bb->index;
3385 delete_basic_block (then_bb);
3387 /* Make rest of code believe that the newly created block is the THEN_BB
3388 block we removed. */
3389 if (new_bb)
3391 new_bb->index = then_bb_index;
3392 SET_BASIC_BLOCK (then_bb_index, new_bb);
3393 /* Since the fallthru edge was redirected from test_bb to new_bb,
3394 we need to ensure that new_bb is in the same partition as
3395 test bb (you can not fall through across section boundaries). */
3396 BB_COPY_PARTITION (new_bb, test_bb);
3398 /* We've possibly created jump to next insn, cleanup_cfg will solve that
3399 later. */
3401 num_true_changes++;
3402 num_updated_if_blocks++;
3404 return TRUE;
3407 /* Test for case 2 above. */
3409 static int
3410 find_if_case_2 (basic_block test_bb, edge then_edge, edge else_edge)
3412 basic_block then_bb = then_edge->dest;
3413 basic_block else_bb = else_edge->dest;
3414 edge else_succ;
3415 rtx note;
3417 /* If we are partitioning hot/cold basic blocks, we don't want to
3418 mess up unconditional or indirect jumps that cross between hot
3419 and cold sections.
3421 Basic block partitioning may result in some jumps that appear to
3422 be optimizable (or blocks that appear to be mergeable), but which really
3423 must be left untouched (they are required to make it safely across
3424 partition boundaries). See the comments at the top of
3425 bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */
3427 if ((BB_END (then_bb)
3428 && find_reg_note (BB_END (then_bb), REG_CROSSING_JUMP, NULL_RTX))
3429 || (BB_END (test_bb)
3430 && find_reg_note (BB_END (test_bb), REG_CROSSING_JUMP, NULL_RTX))
3431 || (BB_END (else_bb)
3432 && find_reg_note (BB_END (else_bb), REG_CROSSING_JUMP,
3433 NULL_RTX)))
3434 return FALSE;
3436 /* ELSE has one successor. */
3437 if (!single_succ_p (else_bb))
3438 return FALSE;
3439 else
3440 else_succ = single_succ_edge (else_bb);
3442 /* ELSE outgoing edge is not complex. */
3443 if (else_succ->flags & EDGE_COMPLEX)
3444 return FALSE;
3446 /* ELSE has one predecessor. */
3447 if (!single_pred_p (else_bb))
3448 return FALSE;
3450 /* THEN is not EXIT. */
3451 if (then_bb->index < NUM_FIXED_BLOCKS)
3452 return FALSE;
3454 /* ELSE is predicted or SUCC(ELSE) postdominates THEN. */
3455 note = find_reg_note (BB_END (test_bb), REG_BR_PROB, NULL_RTX);
3456 if (note && INTVAL (XEXP (note, 0)) >= REG_BR_PROB_BASE / 2)
3458 else if (else_succ->dest->index < NUM_FIXED_BLOCKS
3459 || dominated_by_p (CDI_POST_DOMINATORS, then_bb,
3460 else_succ->dest))
3462 else
3463 return FALSE;
3465 num_possible_if_blocks++;
3466 if (dump_file)
3467 fprintf (dump_file,
3468 "\nIF-CASE-2 found, start %d, else %d\n",
3469 test_bb->index, else_bb->index);
3471 /* ELSE is small. */
3472 if (! cheap_bb_rtx_cost_p (else_bb, COSTS_N_INSNS (BRANCH_COST)))
3473 return FALSE;
3475 /* Registers set are dead, or are predicable. */
3476 if (! dead_or_predicable (test_bb, else_bb, then_bb, else_succ->dest, 0))
3477 return FALSE;
3479 /* Conversion went ok, including moving the insns and fixing up the
3480 jump. Adjust the CFG to match. */
3482 bitmap_ior (test_bb->il.rtl->global_live_at_end,
3483 then_bb->il.rtl->global_live_at_start,
3484 else_bb->il.rtl->global_live_at_end);
3486 delete_basic_block (else_bb);
3488 num_true_changes++;
3489 num_updated_if_blocks++;
3491 /* ??? We may now fallthru from one of THEN's successors into a join
3492 block. Rerun cleanup_cfg? Examine things manually? Wait? */
3494 return TRUE;
3497 /* A subroutine of dead_or_predicable called through for_each_rtx.
3498 Return 1 if a memory is found. */
3500 static int
3501 find_memory (rtx *px, void *data ATTRIBUTE_UNUSED)
3503 return MEM_P (*px);
3506 /* Used by the code above to perform the actual rtl transformations.
3507 Return TRUE if successful.
3509 TEST_BB is the block containing the conditional branch. MERGE_BB
3510 is the block containing the code to manipulate. NEW_DEST is the
3511 label TEST_BB should be branching to after the conversion.
3512 REVERSEP is true if the sense of the branch should be reversed. */
3514 static int
3515 dead_or_predicable (basic_block test_bb, basic_block merge_bb,
3516 basic_block other_bb, basic_block new_dest, int reversep)
3518 rtx head, end, jump, earliest = NULL_RTX, old_dest, new_label = NULL_RTX;
3520 jump = BB_END (test_bb);
3522 /* Find the extent of the real code in the merge block. */
3523 head = BB_HEAD (merge_bb);
3524 end = BB_END (merge_bb);
3526 if (LABEL_P (head))
3527 head = NEXT_INSN (head);
3528 if (NOTE_P (head))
3530 if (head == end)
3532 head = end = NULL_RTX;
3533 goto no_body;
3535 head = NEXT_INSN (head);
3538 if (JUMP_P (end))
3540 if (head == end)
3542 head = end = NULL_RTX;
3543 goto no_body;
3545 end = PREV_INSN (end);
3548 /* Disable handling dead code by conditional execution if the machine needs
3549 to do anything funny with the tests, etc. */
3550 #ifndef IFCVT_MODIFY_TESTS
3551 if (HAVE_conditional_execution)
3553 /* In the conditional execution case, we have things easy. We know
3554 the condition is reversible. We don't have to check life info
3555 because we're going to conditionally execute the code anyway.
3556 All that's left is making sure the insns involved can actually
3557 be predicated. */
3559 rtx cond, prob_val;
3561 cond = cond_exec_get_condition (jump);
3562 if (! cond)
3563 return FALSE;
3565 prob_val = find_reg_note (jump, REG_BR_PROB, NULL_RTX);
3566 if (prob_val)
3567 prob_val = XEXP (prob_val, 0);
3569 if (reversep)
3571 enum rtx_code rev = reversed_comparison_code (cond, jump);
3572 if (rev == UNKNOWN)
3573 return FALSE;
3574 cond = gen_rtx_fmt_ee (rev, GET_MODE (cond), XEXP (cond, 0),
3575 XEXP (cond, 1));
3576 if (prob_val)
3577 prob_val = GEN_INT (REG_BR_PROB_BASE - INTVAL (prob_val));
3580 if (! cond_exec_process_insns ((ce_if_block_t *)0, head, end, cond,
3581 prob_val, 0))
3582 goto cancel;
3584 earliest = jump;
3586 else
3587 #endif
3589 /* In the non-conditional execution case, we have to verify that there
3590 are no trapping operations, no calls, no references to memory, and
3591 that any registers modified are dead at the branch site. */
3593 rtx insn, cond, prev;
3594 regset merge_set, tmp, test_live, test_set;
3595 struct propagate_block_info *pbi;
3596 unsigned i, fail = 0;
3597 bitmap_iterator bi;
3599 /* Check for no calls or trapping operations. */
3600 for (insn = head; ; insn = NEXT_INSN (insn))
3602 if (CALL_P (insn))
3603 return FALSE;
3604 if (INSN_P (insn))
3606 if (may_trap_p (PATTERN (insn)))
3607 return FALSE;
3609 /* ??? Even non-trapping memories such as stack frame
3610 references must be avoided. For stores, we collect
3611 no lifetime info; for reads, we'd have to assert
3612 true_dependence false against every store in the
3613 TEST range. */
3614 if (for_each_rtx (&PATTERN (insn), find_memory, NULL))
3615 return FALSE;
3617 if (insn == end)
3618 break;
3621 if (! any_condjump_p (jump))
3622 return FALSE;
3624 /* Find the extent of the conditional. */
3625 cond = noce_get_condition (jump, &earliest);
3626 if (! cond)
3627 return FALSE;
3629 /* Collect:
3630 MERGE_SET = set of registers set in MERGE_BB
3631 TEST_LIVE = set of registers live at EARLIEST
3632 TEST_SET = set of registers set between EARLIEST and the
3633 end of the block. */
3635 tmp = ALLOC_REG_SET (&reg_obstack);
3636 merge_set = ALLOC_REG_SET (&reg_obstack);
3637 test_live = ALLOC_REG_SET (&reg_obstack);
3638 test_set = ALLOC_REG_SET (&reg_obstack);
3640 /* ??? bb->local_set is only valid during calculate_global_regs_live,
3641 so we must recompute usage for MERGE_BB. Not so bad, I suppose,
3642 since we've already asserted that MERGE_BB is small. */
3643 /* If we allocated new pseudos (e.g. in the conditional move
3644 expander called from noce_emit_cmove), we must resize the
3645 array first. */
3646 if (max_regno < max_reg_num ())
3648 max_regno = max_reg_num ();
3649 allocate_reg_info (max_regno, FALSE, FALSE);
3651 propagate_block (merge_bb, tmp, merge_set, merge_set, 0);
3653 /* For small register class machines, don't lengthen lifetimes of
3654 hard registers before reload. */
3655 if (SMALL_REGISTER_CLASSES && ! reload_completed)
3657 EXECUTE_IF_SET_IN_BITMAP (merge_set, 0, i, bi)
3659 if (i < FIRST_PSEUDO_REGISTER
3660 && ! fixed_regs[i]
3661 && ! global_regs[i])
3662 fail = 1;
3666 /* For TEST, we're interested in a range of insns, not a whole block.
3667 Moreover, we're interested in the insns live from OTHER_BB. */
3669 COPY_REG_SET (test_live, other_bb->il.rtl->global_live_at_start);
3670 pbi = init_propagate_block_info (test_bb, test_live, test_set, test_set,
3673 for (insn = jump; ; insn = prev)
3675 prev = propagate_one_insn (pbi, insn);
3676 if (insn == earliest)
3677 break;
3680 free_propagate_block_info (pbi);
3682 /* We can perform the transformation if
3683 MERGE_SET & (TEST_SET | TEST_LIVE)
3685 TEST_SET & merge_bb->il.rtl->global_live_at_start
3686 are empty. */
3688 if (bitmap_intersect_p (test_set, merge_set)
3689 || bitmap_intersect_p (test_live, merge_set)
3690 || bitmap_intersect_p (test_set,
3691 merge_bb->il.rtl->global_live_at_start))
3692 fail = 1;
3694 FREE_REG_SET (tmp);
3695 FREE_REG_SET (merge_set);
3696 FREE_REG_SET (test_live);
3697 FREE_REG_SET (test_set);
3699 if (fail)
3700 return FALSE;
3703 no_body:
3704 /* We don't want to use normal invert_jump or redirect_jump because
3705 we don't want to delete_insn called. Also, we want to do our own
3706 change group management. */
3708 old_dest = JUMP_LABEL (jump);
3709 if (other_bb != new_dest)
3711 new_label = block_label (new_dest);
3712 if (reversep
3713 ? ! invert_jump_1 (jump, new_label)
3714 : ! redirect_jump_1 (jump, new_label))
3715 goto cancel;
3718 if (! apply_change_group ())
3719 return FALSE;
3721 if (other_bb != new_dest)
3723 redirect_jump_2 (jump, old_dest, new_label, -1, reversep);
3725 redirect_edge_succ (BRANCH_EDGE (test_bb), new_dest);
3726 if (reversep)
3728 gcov_type count, probability;
3729 count = BRANCH_EDGE (test_bb)->count;
3730 BRANCH_EDGE (test_bb)->count = FALLTHRU_EDGE (test_bb)->count;
3731 FALLTHRU_EDGE (test_bb)->count = count;
3732 probability = BRANCH_EDGE (test_bb)->probability;
3733 BRANCH_EDGE (test_bb)->probability
3734 = FALLTHRU_EDGE (test_bb)->probability;
3735 FALLTHRU_EDGE (test_bb)->probability = probability;
3736 update_br_prob_note (test_bb);
3740 /* Move the insns out of MERGE_BB to before the branch. */
3741 if (head != NULL)
3743 rtx insn;
3745 if (end == BB_END (merge_bb))
3746 BB_END (merge_bb) = PREV_INSN (head);
3748 if (squeeze_notes (&head, &end))
3749 return TRUE;
3751 /* PR 21767: When moving insns above a conditional branch, REG_EQUAL
3752 notes might become invalid. */
3753 insn = head;
3756 rtx note, set;
3758 if (! INSN_P (insn))
3759 continue;
3760 note = find_reg_note (insn, REG_EQUAL, NULL_RTX);
3761 if (! note)
3762 continue;
3763 set = single_set (insn);
3764 if (!set || !function_invariant_p (SET_SRC (set)))
3765 remove_note (insn, note);
3766 } while (insn != end && (insn = NEXT_INSN (insn)));
3768 reorder_insns (head, end, PREV_INSN (earliest));
3771 /* Remove the jump and edge if we can. */
3772 if (other_bb == new_dest)
3774 delete_insn (jump);
3775 remove_edge (BRANCH_EDGE (test_bb));
3776 /* ??? Can't merge blocks here, as then_bb is still in use.
3777 At minimum, the merge will get done just before bb-reorder. */
3780 return TRUE;
3782 cancel:
3783 cancel_changes (0);
3784 return FALSE;
3787 /* Main entry point for all if-conversion. */
3789 static void
3790 if_convert (int x_life_data_ok)
3792 basic_block bb;
3793 int pass;
3795 num_possible_if_blocks = 0;
3796 num_updated_if_blocks = 0;
3797 num_true_changes = 0;
3798 life_data_ok = (x_life_data_ok != 0);
3800 if ((! targetm.cannot_modify_jumps_p ())
3801 && (!flag_reorder_blocks_and_partition || !no_new_pseudos
3802 || !targetm.have_named_sections))
3804 struct loops loops;
3806 flow_loops_find (&loops);
3807 mark_loop_exit_edges (&loops);
3808 flow_loops_free (&loops);
3809 free_dominance_info (CDI_DOMINATORS);
3812 /* Compute postdominators if we think we'll use them. */
3813 if (HAVE_conditional_execution || life_data_ok)
3814 calculate_dominance_info (CDI_POST_DOMINATORS);
3816 if (life_data_ok)
3817 clear_bb_flags ();
3819 /* Go through each of the basic blocks looking for things to convert. If we
3820 have conditional execution, we make multiple passes to allow us to handle
3821 IF-THEN{-ELSE} blocks within other IF-THEN{-ELSE} blocks. */
3822 pass = 0;
3825 cond_exec_changed_p = FALSE;
3826 pass++;
3828 #ifdef IFCVT_MULTIPLE_DUMPS
3829 if (dump_file && pass > 1)
3830 fprintf (dump_file, "\n\n========== Pass %d ==========\n", pass);
3831 #endif
3833 FOR_EACH_BB (bb)
3835 basic_block new_bb;
3836 while ((new_bb = find_if_header (bb, pass)))
3837 bb = new_bb;
3840 #ifdef IFCVT_MULTIPLE_DUMPS
3841 if (dump_file && cond_exec_changed_p)
3842 print_rtl_with_bb (dump_file, get_insns ());
3843 #endif
3845 while (cond_exec_changed_p);
3847 #ifdef IFCVT_MULTIPLE_DUMPS
3848 if (dump_file)
3849 fprintf (dump_file, "\n\n========== no more changes\n");
3850 #endif
3852 free_dominance_info (CDI_POST_DOMINATORS);
3854 if (dump_file)
3855 fflush (dump_file);
3857 clear_aux_for_blocks ();
3859 /* Rebuild life info for basic blocks that require it. */
3860 if (num_true_changes && life_data_ok)
3862 /* If we allocated new pseudos, we must resize the array for sched1. */
3863 if (max_regno < max_reg_num ())
3865 max_regno = max_reg_num ();
3866 allocate_reg_info (max_regno, FALSE, FALSE);
3868 update_life_info_in_dirty_blocks (UPDATE_LIFE_GLOBAL_RM_NOTES,
3869 PROP_DEATH_NOTES | PROP_SCAN_DEAD_CODE
3870 | PROP_KILL_DEAD_CODE);
3873 /* Write the final stats. */
3874 if (dump_file && num_possible_if_blocks > 0)
3876 fprintf (dump_file,
3877 "\n%d possible IF blocks searched.\n",
3878 num_possible_if_blocks);
3879 fprintf (dump_file,
3880 "%d IF blocks converted.\n",
3881 num_updated_if_blocks);
3882 fprintf (dump_file,
3883 "%d true changes made.\n\n\n",
3884 num_true_changes);
3887 #ifdef ENABLE_CHECKING
3888 verify_flow_info ();
3889 #endif
3892 static bool
3893 gate_handle_if_conversion (void)
3895 return (optimize > 0);
3898 /* If-conversion and CFG cleanup. */
3899 static void
3900 rest_of_handle_if_conversion (void)
3902 if (flag_if_conversion)
3904 if (dump_file)
3905 dump_flow_info (dump_file);
3906 cleanup_cfg (CLEANUP_EXPENSIVE);
3907 reg_scan (get_insns (), max_reg_num ());
3908 if_convert (0);
3911 timevar_push (TV_JUMP);
3912 cleanup_cfg (CLEANUP_EXPENSIVE);
3913 reg_scan (get_insns (), max_reg_num ());
3914 timevar_pop (TV_JUMP);
3917 struct tree_opt_pass pass_rtl_ifcvt =
3919 "ce1", /* name */
3920 gate_handle_if_conversion, /* gate */
3921 rest_of_handle_if_conversion, /* execute */
3922 NULL, /* sub */
3923 NULL, /* next */
3924 0, /* static_pass_number */
3925 TV_IFCVT, /* tv_id */
3926 0, /* properties_required */
3927 0, /* properties_provided */
3928 0, /* properties_destroyed */
3929 0, /* todo_flags_start */
3930 TODO_dump_func, /* todo_flags_finish */
3931 'C' /* letter */
3934 static bool
3935 gate_handle_if_after_combine (void)
3937 return (optimize > 0 && flag_if_conversion);
3941 /* Rerun if-conversion, as combine may have simplified things enough
3942 to now meet sequence length restrictions. */
3943 static void
3944 rest_of_handle_if_after_combine (void)
3946 no_new_pseudos = 0;
3947 if_convert (1);
3948 no_new_pseudos = 1;
3951 struct tree_opt_pass pass_if_after_combine =
3953 "ce2", /* name */
3954 gate_handle_if_after_combine, /* gate */
3955 rest_of_handle_if_after_combine, /* execute */
3956 NULL, /* sub */
3957 NULL, /* next */
3958 0, /* static_pass_number */
3959 TV_IFCVT, /* tv_id */
3960 0, /* properties_required */
3961 0, /* properties_provided */
3962 0, /* properties_destroyed */
3963 0, /* todo_flags_start */
3964 TODO_dump_func |
3965 TODO_ggc_collect, /* todo_flags_finish */
3966 'C' /* letter */
3970 static bool
3971 gate_handle_if_after_reload (void)
3973 return (optimize > 0);
3976 static void
3977 rest_of_handle_if_after_reload (void)
3979 /* Last attempt to optimize CFG, as scheduling, peepholing and insn
3980 splitting possibly introduced more crossjumping opportunities. */
3981 cleanup_cfg (CLEANUP_EXPENSIVE
3982 | CLEANUP_UPDATE_LIFE
3983 | (flag_crossjumping ? CLEANUP_CROSSJUMP : 0));
3984 if (flag_if_conversion2)
3985 if_convert (1);
3989 struct tree_opt_pass pass_if_after_reload =
3991 "ce3", /* name */
3992 gate_handle_if_after_reload, /* gate */
3993 rest_of_handle_if_after_reload, /* execute */
3994 NULL, /* sub */
3995 NULL, /* next */
3996 0, /* static_pass_number */
3997 TV_IFCVT2, /* tv_id */
3998 0, /* properties_required */
3999 0, /* properties_provided */
4000 0, /* properties_destroyed */
4001 0, /* todo_flags_start */
4002 TODO_dump_func |
4003 TODO_ggc_collect, /* todo_flags_finish */
4004 'E' /* letter */