1 /* If-conversion support.
2 Copyright (C) 2000, 2001, 2002, 2003 Free Software Foundation, Inc.
4 This file is part of GCC.
6 GCC is free software; you can redistribute it and/or modify it
7 under the terms of the GNU General Public License as published by
8 the Free Software Foundation; either version 2, or (at your option)
11 GCC is distributed in the hope that it will be useful, but WITHOUT
12 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
13 or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public
14 License for more details.
16 You should have received a copy of the GNU General Public License
17 along with GCC; see the file COPYING. If not, write to the Free
18 Software Foundation, 59 Temple Place - Suite 330, Boston, MA
23 #include "coretypes.h"
30 #include "insn-config.h"
33 #include "hard-reg-set.h"
34 #include "basic-block.h"
45 #ifndef HAVE_conditional_execution
46 #define HAVE_conditional_execution 0
48 #ifndef HAVE_conditional_move
49 #define HAVE_conditional_move 0
60 #ifndef HAVE_conditional_trap
61 #define HAVE_conditional_trap 0
64 #ifndef MAX_CONDITIONAL_EXECUTE
65 #define MAX_CONDITIONAL_EXECUTE (BRANCH_COST + 1)
68 #define NULL_EDGE ((struct edge_def *)NULL)
69 #define NULL_BLOCK ((struct basic_block_def *)NULL)
71 /* # of IF-THEN or IF-THEN-ELSE blocks we looked at */
72 static int num_possible_if_blocks;
74 /* # of IF-THEN or IF-THEN-ELSE blocks were converted to conditional
76 static int num_updated_if_blocks;
78 /* # of changes made which require life information to be updated. */
79 static int num_true_changes;
81 /* Whether conditional execution changes were made. */
82 static int cond_exec_changed_p;
84 /* True if life data ok at present. */
85 static bool life_data_ok;
87 /* Forward references. */
88 static int count_bb_insns (basic_block);
89 static rtx first_active_insn (basic_block);
90 static rtx last_active_insn (basic_block, int);
91 static int seq_contains_jump (rtx);
92 static basic_block block_fallthru (basic_block);
93 static int cond_exec_process_insns (ce_if_block_t *, rtx, rtx, rtx, rtx, int);
94 static rtx cond_exec_get_condition (rtx);
95 static int cond_exec_process_if_block (ce_if_block_t *, int);
96 static rtx noce_get_condition (rtx, rtx *);
97 static int noce_operand_ok (rtx);
98 static int noce_process_if_block (ce_if_block_t *);
99 static int process_if_block (ce_if_block_t *);
100 static void merge_if_block (ce_if_block_t *);
101 static int find_cond_trap (basic_block, edge, edge);
102 static basic_block find_if_header (basic_block, int);
103 static int block_jumps_and_fallthru_p (basic_block, basic_block);
104 static int find_if_block (ce_if_block_t *);
105 static int find_if_case_1 (basic_block, edge, edge);
106 static int find_if_case_2 (basic_block, edge, edge);
107 static int find_memory (rtx *, void *);
108 static int dead_or_predicable (basic_block, basic_block, basic_block,
110 static void noce_emit_move_insn (rtx, rtx);
111 static rtx block_has_only_trap (basic_block);
112 static void mark_loop_exit_edges (void);
114 /* Sets EDGE_LOOP_EXIT flag for all loop exits. */
116 mark_loop_exit_edges (void)
122 flow_loops_find (&loops, LOOP_TREE);
123 free_dominance_info (CDI_DOMINATORS);
129 for (e = bb->succ; e; e = e->succ_next)
131 if (find_common_loop (bb->loop_father, e->dest->loop_father)
133 e->flags |= EDGE_LOOP_EXIT;
135 e->flags &= ~EDGE_LOOP_EXIT;
140 flow_loops_free (&loops);
143 /* Count the number of non-jump active insns in BB. */
146 count_bb_insns (basic_block bb)
149 rtx insn = BB_HEAD (bb);
153 if (GET_CODE (insn) == CALL_INSN || GET_CODE (insn) == INSN)
156 if (insn == BB_END (bb))
158 insn = NEXT_INSN (insn);
164 /* Return the first non-jump active insn in the basic block. */
167 first_active_insn (basic_block bb)
169 rtx insn = BB_HEAD (bb);
171 if (GET_CODE (insn) == CODE_LABEL)
173 if (insn == BB_END (bb))
175 insn = NEXT_INSN (insn);
178 while (GET_CODE (insn) == NOTE)
180 if (insn == BB_END (bb))
182 insn = NEXT_INSN (insn);
185 if (GET_CODE (insn) == JUMP_INSN)
191 /* Return the last non-jump active (non-jump) insn in the basic block. */
194 last_active_insn (basic_block bb, int skip_use_p)
196 rtx insn = BB_END (bb);
197 rtx head = BB_HEAD (bb);
199 while (GET_CODE (insn) == NOTE
200 || GET_CODE (insn) == JUMP_INSN
202 && GET_CODE (insn) == INSN
203 && GET_CODE (PATTERN (insn)) == USE))
207 insn = PREV_INSN (insn);
210 if (GET_CODE (insn) == CODE_LABEL)
216 /* It is possible, especially when having dealt with multi-word
217 arithmetic, for the expanders to have emitted jumps. Search
218 through the sequence and return TRUE if a jump exists so that
219 we can abort the conversion. */
222 seq_contains_jump (rtx insn)
226 if (GET_CODE (insn) == JUMP_INSN)
228 insn = NEXT_INSN (insn);
234 block_fallthru (basic_block bb)
239 e != NULL_EDGE && (e->flags & EDGE_FALLTHRU) == 0;
243 return (e) ? e->dest : NULL_BLOCK;
246 /* Go through a bunch of insns, converting them to conditional
247 execution format if possible. Return TRUE if all of the non-note
248 insns were processed. */
251 cond_exec_process_insns (ce_if_block_t *ce_info ATTRIBUTE_UNUSED,
252 /* if block information */rtx start,
253 /* first insn to look at */rtx end,
254 /* last insn to look at */rtx test,
255 /* conditional execution test */rtx prob_val,
256 /* probability of branch taken. */int mod_ok)
258 int must_be_last = FALSE;
266 for (insn = start; ; insn = NEXT_INSN (insn))
268 if (GET_CODE (insn) == NOTE)
271 if (GET_CODE (insn) != INSN && GET_CODE (insn) != CALL_INSN)
274 /* Remove USE insns that get in the way. */
275 if (reload_completed && GET_CODE (PATTERN (insn)) == USE)
277 /* ??? Ug. Actually unlinking the thing is problematic,
278 given what we'd have to coordinate with our callers. */
279 PUT_CODE (insn, NOTE);
280 NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED;
281 NOTE_SOURCE_FILE (insn) = 0;
285 /* Last insn wasn't last? */
289 if (modified_in_p (test, insn))
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
302 if (GET_CODE (pattern) == COND_EXEC)
304 if (GET_MODE (xtest) != GET_MODE (COND_EXEC_TEST (pattern)))
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);
323 validate_change (insn, &PATTERN (insn), pattern, 1);
325 if (GET_CODE (insn) == CALL_INSN && prob_val)
326 validate_change (insn, ®_NOTES (insn),
327 alloc_EXPR_LIST (REG_BR_PROB, prob_val,
328 REG_NOTES (insn)), 1);
338 /* Return the condition for a jump. Do not do any special processing. */
341 cond_exec_get_condition (rtx jump)
345 if (any_condjump_p (jump))
346 test_if = SET_SRC (pc_set (jump));
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);
360 cond = gen_rtx_fmt_ee (rev, GET_MODE (cond), XEXP (cond, 0),
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. */
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 */
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)
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
408 test_expr = cond_exec_get_condition (BB_END (test_bb));
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)))
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;
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);
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));
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)
458 true_prob_val = find_reg_note (BB_END (test_bb), REG_BR_PROB, NULL_RTX);
461 true_prob_val = XEXP (true_prob_val, 0);
462 false_prob_val = GEN_INT (REG_BR_PROB_BASE - INTVAL (true_prob_val));
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;
482 bb = block_fallthru (bb);
483 start = first_active_insn (bb);
484 end = last_active_insn (bb, TRUE);
486 && ! cond_exec_process_insns (ce_info, start, end, false_expr,
487 false_prob_val, FALSE))
490 /* If the conditional jump is more than just a conditional jump, then
491 we can not do conditional execution conversion on this block. */
492 if (! onlyjump_p (BB_END (bb)))
495 /* Find the conditional jump and isolate the test. */
496 t = cond_exec_get_condition (BB_END (bb));
500 f = gen_rtx_fmt_ee (reverse_condition (GET_CODE (t)),
505 if (ce_info->and_and_p)
507 t = gen_rtx_AND (GET_MODE (t), true_expr, t);
508 f = gen_rtx_IOR (GET_MODE (t), false_expr, f);
512 t = gen_rtx_IOR (GET_MODE (t), true_expr, t);
513 f = gen_rtx_AND (GET_MODE (t), false_expr, f);
516 /* If the machine description needs to modify the tests, such as
517 setting a conditional execution register from a comparison, it can
519 #ifdef IFCVT_MODIFY_MULTIPLE_TESTS
520 IFCVT_MODIFY_MULTIPLE_TESTS (ce_info, bb, t, f);
522 /* See if the conversion failed. */
530 while (bb != last_test_bb);
533 /* For IF-THEN-ELSE blocks, we don't allow modifications of the test
534 on then THEN block. */
535 then_mod_ok = (else_bb == NULL_BLOCK);
537 /* Go through the THEN and ELSE blocks converting the insns if possible
538 to conditional execution. */
542 || ! cond_exec_process_insns (ce_info, then_start, then_end,
543 false_expr, false_prob_val,
547 if (else_bb && else_end
548 && ! cond_exec_process_insns (ce_info, else_start, else_end,
549 true_expr, true_prob_val, TRUE))
552 /* If we cannot apply the changes, fail. Do not go through the normal fail
553 processing, since apply_change_group will call cancel_changes. */
554 if (! apply_change_group ())
556 #ifdef IFCVT_MODIFY_CANCEL
557 /* Cancel any machine dependent changes. */
558 IFCVT_MODIFY_CANCEL (ce_info);
563 #ifdef IFCVT_MODIFY_FINAL
564 /* Do any machine dependent final modifications. */
565 IFCVT_MODIFY_FINAL (ce_info);
568 /* Conversion succeeded. */
570 fprintf (rtl_dump_file, "%d insn%s converted to conditional execution.\n",
571 n_insns, (n_insns == 1) ? " was" : "s were");
573 /* Merge the blocks! */
574 merge_if_block (ce_info);
575 cond_exec_changed_p = TRUE;
579 #ifdef IFCVT_MODIFY_CANCEL
580 /* Cancel any machine dependent changes. */
581 IFCVT_MODIFY_CANCEL (ce_info);
588 /* Used by noce_process_if_block to communicate with its subroutines.
590 The subroutines know that A and B may be evaluated freely. They
591 know that X is a register. They should insert new instructions
592 before cond_earliest. */
599 rtx jump, cond, cond_earliest;
602 static rtx noce_emit_store_flag (struct noce_if_info *, rtx, int, int);
603 static int noce_try_move (struct noce_if_info *);
604 static int noce_try_store_flag (struct noce_if_info *);
605 static int noce_try_addcc (struct noce_if_info *);
606 static int noce_try_store_flag_constants (struct noce_if_info *);
607 static int noce_try_store_flag_mask (struct noce_if_info *);
608 static rtx noce_emit_cmove (struct noce_if_info *, rtx, enum rtx_code, rtx,
610 static int noce_try_cmove (struct noce_if_info *);
611 static int noce_try_cmove_arith (struct noce_if_info *);
612 static rtx noce_get_alt_condition (struct noce_if_info *, rtx, rtx *);
613 static int noce_try_minmax (struct noce_if_info *);
614 static int noce_try_abs (struct noce_if_info *);
616 /* Helper function for noce_try_store_flag*. */
619 noce_emit_store_flag (struct noce_if_info *if_info, rtx x, int reversep,
622 rtx cond = if_info->cond;
626 cond_complex = (! general_operand (XEXP (cond, 0), VOIDmode)
627 || ! general_operand (XEXP (cond, 1), VOIDmode));
629 /* If earliest == jump, or when the condition is complex, try to
630 build the store_flag insn directly. */
633 cond = XEXP (SET_SRC (pc_set (if_info->jump)), 0);
636 code = reversed_comparison_code (cond, if_info->jump);
638 code = GET_CODE (cond);
640 if ((if_info->cond_earliest == if_info->jump || cond_complex)
641 && (normalize == 0 || STORE_FLAG_VALUE == normalize))
645 tmp = gen_rtx_fmt_ee (code, GET_MODE (x), XEXP (cond, 0),
647 tmp = gen_rtx_SET (VOIDmode, x, tmp);
650 tmp = emit_insn (tmp);
652 if (recog_memoized (tmp) >= 0)
658 if_info->cond_earliest = if_info->jump;
666 /* Don't even try if the comparison operands or the mode of X are weird. */
667 if (cond_complex || !SCALAR_INT_MODE_P (GET_MODE (x)))
670 return emit_store_flag (x, code, XEXP (cond, 0),
671 XEXP (cond, 1), VOIDmode,
672 (code == LTU || code == LEU
673 || code == GEU || code == GTU), normalize);
676 /* Emit instruction to move an rtx, possibly into STRICT_LOW_PART.
677 X is the destination/target and Y is the value to copy. */
680 noce_emit_move_insn (rtx x, rtx y)
682 enum machine_mode outmode, inmode;
686 if (GET_CODE (x) != STRICT_LOW_PART)
688 emit_move_insn (x, y);
693 inner = XEXP (outer, 0);
694 outmode = GET_MODE (outer);
695 inmode = GET_MODE (inner);
696 bitpos = SUBREG_BYTE (outer) * BITS_PER_UNIT;
697 store_bit_field (inner, GET_MODE_BITSIZE (outmode), bitpos, outmode, y,
698 GET_MODE_BITSIZE (inmode));
701 /* Unshare sequence SEQ produced by if conversion. We care to mark
702 all arguments that may be shared with outer instruction stream. */
704 unshare_ifcvt_sequence (struct noce_if_info *if_info, rtx seq)
706 set_used_flags (if_info->x);
707 set_used_flags (if_info->cond);
708 unshare_all_rtl_in_chain (seq);
711 /* Convert "if (a != b) x = a; else x = b" into "x = a" and
712 "if (a == b) x = a; else x = b" into "x = b". */
715 noce_try_move (struct noce_if_info *if_info)
717 rtx cond = if_info->cond;
718 enum rtx_code code = GET_CODE (cond);
721 if (code != NE && code != EQ)
724 /* This optimization isn't valid if either A or B could be a NaN
726 if (HONOR_NANS (GET_MODE (if_info->x))
727 || HONOR_SIGNED_ZEROS (GET_MODE (if_info->x)))
730 /* Check whether the operands of the comparison are A and in
732 if ((rtx_equal_p (if_info->a, XEXP (cond, 0))
733 && rtx_equal_p (if_info->b, XEXP (cond, 1)))
734 || (rtx_equal_p (if_info->a, XEXP (cond, 1))
735 && rtx_equal_p (if_info->b, XEXP (cond, 0))))
737 y = (code == EQ) ? if_info->a : if_info->b;
739 /* Avoid generating the move if the source is the destination. */
740 if (! rtx_equal_p (if_info->x, y))
743 noce_emit_move_insn (if_info->x, y);
745 unshare_ifcvt_sequence (if_info, seq);
748 /* Make sure that all of the instructions emitted are
749 recognizable. As an excersise for the reader, build
750 a general mechanism that allows proper placement of
751 required clobbers. */
752 for (y = seq; y ; y = NEXT_INSN (y))
753 if (recog_memoized (y) == -1)
756 emit_insn_before_setloc (seq, if_info->jump,
757 INSN_LOCATOR (if_info->insn_a));
764 /* Convert "if (test) x = 1; else x = 0".
766 Only try 0 and STORE_FLAG_VALUE here. Other combinations will be
767 tried in noce_try_store_flag_constants after noce_try_cmove has had
768 a go at the conversion. */
771 noce_try_store_flag (struct noce_if_info *if_info)
776 if (GET_CODE (if_info->b) == CONST_INT
777 && INTVAL (if_info->b) == STORE_FLAG_VALUE
778 && if_info->a == const0_rtx)
780 else if (if_info->b == const0_rtx
781 && GET_CODE (if_info->a) == CONST_INT
782 && INTVAL (if_info->a) == STORE_FLAG_VALUE
783 && (reversed_comparison_code (if_info->cond, if_info->jump)
791 target = noce_emit_store_flag (if_info, if_info->x, reversep, 0);
794 if (target != if_info->x)
795 noce_emit_move_insn (if_info->x, target);
798 unshare_ifcvt_sequence (if_info, seq);
800 emit_insn_before_setloc (seq, if_info->jump, INSN_LOCATOR (if_info->insn_a));
811 /* Convert "if (test) x = a; else x = b", for A and B constant. */
814 noce_try_store_flag_constants (struct noce_if_info *if_info)
818 HOST_WIDE_INT itrue, ifalse, diff, tmp;
819 int normalize, can_reverse;
820 enum machine_mode mode;
823 && GET_CODE (if_info->a) == CONST_INT
824 && GET_CODE (if_info->b) == CONST_INT)
826 mode = GET_MODE (if_info->x);
827 ifalse = INTVAL (if_info->a);
828 itrue = INTVAL (if_info->b);
830 /* Make sure we can represent the difference between the two values. */
831 if ((itrue - ifalse > 0)
832 != ((ifalse < 0) != (itrue < 0) ? ifalse < 0 : ifalse < itrue))
835 diff = trunc_int_for_mode (itrue - ifalse, mode);
837 can_reverse = (reversed_comparison_code (if_info->cond, if_info->jump)
841 if (diff == STORE_FLAG_VALUE || diff == -STORE_FLAG_VALUE)
843 else if (ifalse == 0 && exact_log2 (itrue) >= 0
844 && (STORE_FLAG_VALUE == 1
845 || BRANCH_COST >= 2))
847 else if (itrue == 0 && exact_log2 (ifalse) >= 0 && can_reverse
848 && (STORE_FLAG_VALUE == 1 || BRANCH_COST >= 2))
849 normalize = 1, reversep = 1;
851 && (STORE_FLAG_VALUE == -1
852 || BRANCH_COST >= 2))
854 else if (ifalse == -1 && can_reverse
855 && (STORE_FLAG_VALUE == -1 || BRANCH_COST >= 2))
856 normalize = -1, reversep = 1;
857 else if ((BRANCH_COST >= 2 && STORE_FLAG_VALUE == -1)
865 tmp = itrue; itrue = ifalse; ifalse = tmp;
866 diff = trunc_int_for_mode (-diff, mode);
870 target = noce_emit_store_flag (if_info, if_info->x, reversep, normalize);
877 /* if (test) x = 3; else x = 4;
878 => x = 3 + (test == 0); */
879 if (diff == STORE_FLAG_VALUE || diff == -STORE_FLAG_VALUE)
881 target = expand_simple_binop (mode,
882 (diff == STORE_FLAG_VALUE
884 GEN_INT (ifalse), target, if_info->x, 0,
888 /* if (test) x = 8; else x = 0;
889 => x = (test != 0) << 3; */
890 else if (ifalse == 0 && (tmp = exact_log2 (itrue)) >= 0)
892 target = expand_simple_binop (mode, ASHIFT,
893 target, GEN_INT (tmp), if_info->x, 0,
897 /* if (test) x = -1; else x = b;
898 => x = -(test != 0) | b; */
899 else if (itrue == -1)
901 target = expand_simple_binop (mode, IOR,
902 target, GEN_INT (ifalse), if_info->x, 0,
906 /* if (test) x = a; else x = b;
907 => x = (-(test != 0) & (b - a)) + a; */
910 target = expand_simple_binop (mode, AND,
911 target, GEN_INT (diff), if_info->x, 0,
914 target = expand_simple_binop (mode, PLUS,
915 target, GEN_INT (ifalse),
916 if_info->x, 0, OPTAB_WIDEN);
925 if (target != if_info->x)
926 noce_emit_move_insn (if_info->x, target);
929 unshare_ifcvt_sequence (if_info, seq);
932 if (seq_contains_jump (seq))
935 emit_insn_before_setloc (seq, if_info->jump, INSN_LOCATOR (if_info->insn_a));
943 /* Convert "if (test) foo++" into "foo += (test != 0)", and
944 similarly for "foo--". */
947 noce_try_addcc (struct noce_if_info *if_info)
950 int subtract, normalize;
953 && GET_CODE (if_info->a) == PLUS
954 && rtx_equal_p (XEXP (if_info->a, 0), if_info->b)
955 && (reversed_comparison_code (if_info->cond, if_info->jump)
958 rtx cond = if_info->cond;
959 enum rtx_code code = reversed_comparison_code (cond, if_info->jump);
961 /* First try to use addcc pattern. */
962 if (general_operand (XEXP (cond, 0), VOIDmode)
963 && general_operand (XEXP (cond, 1), VOIDmode))
966 target = emit_conditional_add (if_info->x, code,
971 XEXP (if_info->a, 1),
972 GET_MODE (if_info->x),
973 (code == LTU || code == GEU
974 || code == LEU || code == GTU));
977 if (target != if_info->x)
978 noce_emit_move_insn (if_info->x, target);
981 unshare_ifcvt_sequence (if_info, seq);
983 emit_insn_before_setloc (seq, if_info->jump,
984 INSN_LOCATOR (if_info->insn_a));
990 /* If that fails, construct conditional increment or decrement using
993 && (XEXP (if_info->a, 1) == const1_rtx
994 || XEXP (if_info->a, 1) == constm1_rtx))
997 if (STORE_FLAG_VALUE == INTVAL (XEXP (if_info->a, 1)))
998 subtract = 0, normalize = 0;
999 else if (-STORE_FLAG_VALUE == INTVAL (XEXP (if_info->a, 1)))
1000 subtract = 1, normalize = 0;
1002 subtract = 0, normalize = INTVAL (XEXP (if_info->a, 1));
1005 target = noce_emit_store_flag (if_info,
1006 gen_reg_rtx (GET_MODE (if_info->x)),
1010 target = expand_simple_binop (GET_MODE (if_info->x),
1011 subtract ? MINUS : PLUS,
1012 if_info->b, target, if_info->x,
1016 if (target != if_info->x)
1017 noce_emit_move_insn (if_info->x, target);
1020 unshare_ifcvt_sequence (if_info, seq);
1023 if (seq_contains_jump (seq))
1026 emit_insn_before_setloc (seq, if_info->jump,
1027 INSN_LOCATOR (if_info->insn_a));
1038 /* Convert "if (test) x = 0;" to "x &= -(test == 0);" */
1041 noce_try_store_flag_mask (struct noce_if_info *if_info)
1047 if (! no_new_pseudos
1048 && (BRANCH_COST >= 2
1049 || STORE_FLAG_VALUE == -1)
1050 && ((if_info->a == const0_rtx
1051 && rtx_equal_p (if_info->b, if_info->x))
1052 || ((reversep = (reversed_comparison_code (if_info->cond,
1055 && if_info->b == const0_rtx
1056 && rtx_equal_p (if_info->a, if_info->x))))
1059 target = noce_emit_store_flag (if_info,
1060 gen_reg_rtx (GET_MODE (if_info->x)),
1063 target = expand_simple_binop (GET_MODE (if_info->x), AND,
1065 target, if_info->x, 0,
1070 if (target != if_info->x)
1071 noce_emit_move_insn (if_info->x, target);
1074 unshare_ifcvt_sequence (if_info, seq);
1077 if (seq_contains_jump (seq))
1080 emit_insn_before_setloc (seq, if_info->jump,
1081 INSN_LOCATOR (if_info->insn_a));
1092 /* Helper function for noce_try_cmove and noce_try_cmove_arith. */
1095 noce_emit_cmove (struct noce_if_info *if_info, rtx x, enum rtx_code code,
1096 rtx cmp_a, rtx cmp_b, rtx vfalse, rtx vtrue)
1098 /* If earliest == jump, try to build the cmove insn directly.
1099 This is helpful when combine has created some complex condition
1100 (like for alpha's cmovlbs) that we can't hope to regenerate
1101 through the normal interface. */
1103 if (if_info->cond_earliest == if_info->jump)
1107 tmp = gen_rtx_fmt_ee (code, GET_MODE (if_info->cond), cmp_a, cmp_b);
1108 tmp = gen_rtx_IF_THEN_ELSE (GET_MODE (x), tmp, vtrue, vfalse);
1109 tmp = gen_rtx_SET (VOIDmode, x, tmp);
1112 tmp = emit_insn (tmp);
1114 if (recog_memoized (tmp) >= 0)
1126 /* Don't even try if the comparison operands are weird. */
1127 if (! general_operand (cmp_a, GET_MODE (cmp_a))
1128 || ! general_operand (cmp_b, GET_MODE (cmp_b)))
1131 #if HAVE_conditional_move
1132 return emit_conditional_move (x, code, cmp_a, cmp_b, VOIDmode,
1133 vtrue, vfalse, GET_MODE (x),
1134 (code == LTU || code == GEU
1135 || code == LEU || code == GTU));
1137 /* We'll never get here, as noce_process_if_block doesn't call the
1138 functions involved. Ifdef code, however, should be discouraged
1139 because it leads to typos in the code not selected. However,
1140 emit_conditional_move won't exist either. */
1145 /* Try only simple constants and registers here. More complex cases
1146 are handled in noce_try_cmove_arith after noce_try_store_flag_arith
1147 has had a go at it. */
1150 noce_try_cmove (struct noce_if_info *if_info)
1155 if ((CONSTANT_P (if_info->a) || register_operand (if_info->a, VOIDmode))
1156 && (CONSTANT_P (if_info->b) || register_operand (if_info->b, VOIDmode)))
1160 code = GET_CODE (if_info->cond);
1161 target = noce_emit_cmove (if_info, if_info->x, code,
1162 XEXP (if_info->cond, 0),
1163 XEXP (if_info->cond, 1),
1164 if_info->a, if_info->b);
1168 if (target != if_info->x)
1169 noce_emit_move_insn (if_info->x, target);
1172 unshare_ifcvt_sequence (if_info, seq);
1174 emit_insn_before_setloc (seq, if_info->jump,
1175 INSN_LOCATOR (if_info->insn_a));
1188 /* Try more complex cases involving conditional_move. */
1191 noce_try_cmove_arith (struct noce_if_info *if_info)
1201 /* A conditional move from two memory sources is equivalent to a
1202 conditional on their addresses followed by a load. Don't do this
1203 early because it'll screw alias analysis. Note that we've
1204 already checked for no side effects. */
1205 if (! no_new_pseudos && cse_not_expected
1206 && GET_CODE (a) == MEM && GET_CODE (b) == MEM
1207 && BRANCH_COST >= 5)
1211 x = gen_reg_rtx (Pmode);
1215 /* ??? We could handle this if we knew that a load from A or B could
1216 not fault. This is also true if we've already loaded
1217 from the address along the path from ENTRY. */
1218 else if (may_trap_p (a) || may_trap_p (b))
1221 /* if (test) x = a + b; else x = c - d;
1228 code = GET_CODE (if_info->cond);
1229 insn_a = if_info->insn_a;
1230 insn_b = if_info->insn_b;
1232 /* Possibly rearrange operands to make things come out more natural. */
1233 if (reversed_comparison_code (if_info->cond, if_info->jump) != UNKNOWN)
1236 if (rtx_equal_p (b, x))
1238 else if (general_operand (b, GET_MODE (b)))
1243 code = reversed_comparison_code (if_info->cond, if_info->jump);
1244 tmp = a, a = b, b = tmp;
1245 tmp = insn_a, insn_a = insn_b, insn_b = tmp;
1251 /* If either operand is complex, load it into a register first.
1252 The best way to do this is to copy the original insn. In this
1253 way we preserve any clobbers etc that the insn may have had.
1254 This is of course not possible in the IS_MEM case. */
1255 if (! general_operand (a, GET_MODE (a)))
1260 goto end_seq_and_fail;
1264 tmp = gen_reg_rtx (GET_MODE (a));
1265 tmp = emit_insn (gen_rtx_SET (VOIDmode, tmp, a));
1268 goto end_seq_and_fail;
1271 a = gen_reg_rtx (GET_MODE (a));
1272 tmp = copy_rtx (insn_a);
1273 set = single_set (tmp);
1275 tmp = emit_insn (PATTERN (tmp));
1277 if (recog_memoized (tmp) < 0)
1278 goto end_seq_and_fail;
1280 if (! general_operand (b, GET_MODE (b)))
1285 goto end_seq_and_fail;
1289 tmp = gen_reg_rtx (GET_MODE (b));
1290 tmp = emit_insn (gen_rtx_SET (VOIDmode,
1295 goto end_seq_and_fail;
1298 b = gen_reg_rtx (GET_MODE (b));
1299 tmp = copy_rtx (insn_b);
1300 set = single_set (tmp);
1302 tmp = emit_insn (PATTERN (tmp));
1304 if (recog_memoized (tmp) < 0)
1305 goto end_seq_and_fail;
1308 target = noce_emit_cmove (if_info, x, code, XEXP (if_info->cond, 0),
1309 XEXP (if_info->cond, 1), a, b);
1312 goto end_seq_and_fail;
1314 /* If we're handling a memory for above, emit the load now. */
1317 tmp = gen_rtx_MEM (GET_MODE (if_info->x), target);
1319 /* Copy over flags as appropriate. */
1320 if (MEM_VOLATILE_P (if_info->a) || MEM_VOLATILE_P (if_info->b))
1321 MEM_VOLATILE_P (tmp) = 1;
1322 if (MEM_IN_STRUCT_P (if_info->a) && MEM_IN_STRUCT_P (if_info->b))
1323 MEM_IN_STRUCT_P (tmp) = 1;
1324 if (MEM_SCALAR_P (if_info->a) && MEM_SCALAR_P (if_info->b))
1325 MEM_SCALAR_P (tmp) = 1;
1326 if (MEM_ALIAS_SET (if_info->a) == MEM_ALIAS_SET (if_info->b))
1327 set_mem_alias_set (tmp, MEM_ALIAS_SET (if_info->a));
1329 MIN (MEM_ALIGN (if_info->a), MEM_ALIGN (if_info->b)));
1331 noce_emit_move_insn (if_info->x, tmp);
1333 else if (target != x)
1334 noce_emit_move_insn (x, target);
1337 unshare_ifcvt_sequence (if_info, tmp);
1339 emit_insn_before_setloc (tmp, if_info->jump, INSN_LOCATOR (if_info->insn_a));
1347 /* For most cases, the simplified condition we found is the best
1348 choice, but this is not the case for the min/max/abs transforms.
1349 For these we wish to know that it is A or B in the condition. */
1352 noce_get_alt_condition (struct noce_if_info *if_info, rtx target,
1355 rtx cond, set, insn;
1358 /* If target is already mentioned in the known condition, return it. */
1359 if (reg_mentioned_p (target, if_info->cond))
1361 *earliest = if_info->cond_earliest;
1362 return if_info->cond;
1365 set = pc_set (if_info->jump);
1366 cond = XEXP (SET_SRC (set), 0);
1368 = GET_CODE (XEXP (SET_SRC (set), 2)) == LABEL_REF
1369 && XEXP (XEXP (SET_SRC (set), 2), 0) == JUMP_LABEL (if_info->jump);
1371 /* If we're looking for a constant, try to make the conditional
1372 have that constant in it. There are two reasons why it may
1373 not have the constant we want:
1375 1. GCC may have needed to put the constant in a register, because
1376 the target can't compare directly against that constant. For
1377 this case, we look for a SET immediately before the comparison
1378 that puts a constant in that register.
1380 2. GCC may have canonicalized the conditional, for example
1381 replacing "if x < 4" with "if x <= 3". We can undo that (or
1382 make equivalent types of changes) to get the constants we need
1383 if they're off by one in the right direction. */
1385 if (GET_CODE (target) == CONST_INT)
1387 enum rtx_code code = GET_CODE (if_info->cond);
1388 rtx op_a = XEXP (if_info->cond, 0);
1389 rtx op_b = XEXP (if_info->cond, 1);
1392 /* First, look to see if we put a constant in a register. */
1393 prev_insn = PREV_INSN (if_info->cond_earliest);
1395 && INSN_P (prev_insn)
1396 && GET_CODE (PATTERN (prev_insn)) == SET)
1398 rtx src = find_reg_equal_equiv_note (prev_insn);
1400 src = SET_SRC (PATTERN (prev_insn));
1401 if (GET_CODE (src) == CONST_INT)
1403 if (rtx_equal_p (op_a, SET_DEST (PATTERN (prev_insn))))
1405 else if (rtx_equal_p (op_b, SET_DEST (PATTERN (prev_insn))))
1408 if (GET_CODE (op_a) == CONST_INT)
1413 code = swap_condition (code);
1418 /* Now, look to see if we can get the right constant by
1419 adjusting the conditional. */
1420 if (GET_CODE (op_b) == CONST_INT)
1422 HOST_WIDE_INT desired_val = INTVAL (target);
1423 HOST_WIDE_INT actual_val = INTVAL (op_b);
1428 if (actual_val == desired_val + 1)
1431 op_b = GEN_INT (desired_val);
1435 if (actual_val == desired_val - 1)
1438 op_b = GEN_INT (desired_val);
1442 if (actual_val == desired_val - 1)
1445 op_b = GEN_INT (desired_val);
1449 if (actual_val == desired_val + 1)
1452 op_b = GEN_INT (desired_val);
1460 /* If we made any changes, generate a new conditional that is
1461 equivalent to what we started with, but has the right
1463 if (code != GET_CODE (if_info->cond)
1464 || op_a != XEXP (if_info->cond, 0)
1465 || op_b != XEXP (if_info->cond, 1))
1467 cond = gen_rtx_fmt_ee (code, GET_MODE (cond), op_a, op_b);
1468 *earliest = if_info->cond_earliest;
1473 cond = canonicalize_condition (if_info->jump, cond, reverse,
1474 earliest, target, false);
1475 if (! cond || ! reg_mentioned_p (target, cond))
1478 /* We almost certainly searched back to a different place.
1479 Need to re-verify correct lifetimes. */
1481 /* X may not be mentioned in the range (cond_earliest, jump]. */
1482 for (insn = if_info->jump; insn != *earliest; insn = PREV_INSN (insn))
1483 if (INSN_P (insn) && reg_overlap_mentioned_p (if_info->x, PATTERN (insn)))
1486 /* A and B may not be modified in the range [cond_earliest, jump). */
1487 for (insn = *earliest; insn != if_info->jump; insn = NEXT_INSN (insn))
1489 && (modified_in_p (if_info->a, insn)
1490 || modified_in_p (if_info->b, insn)))
1496 /* Convert "if (a < b) x = a; else x = b;" to "x = min(a, b);", etc. */
1499 noce_try_minmax (struct noce_if_info *if_info)
1501 rtx cond, earliest, target, seq;
1502 enum rtx_code code, op;
1505 /* ??? Can't guarantee that expand_binop won't create pseudos. */
1509 /* ??? Reject modes with NaNs or signed zeros since we don't know how
1510 they will be resolved with an SMIN/SMAX. It wouldn't be too hard
1511 to get the target to tell us... */
1512 if (HONOR_SIGNED_ZEROS (GET_MODE (if_info->x))
1513 || HONOR_NANS (GET_MODE (if_info->x)))
1516 cond = noce_get_alt_condition (if_info, if_info->a, &earliest);
1520 /* Verify the condition is of the form we expect, and canonicalize
1521 the comparison code. */
1522 code = GET_CODE (cond);
1523 if (rtx_equal_p (XEXP (cond, 0), if_info->a))
1525 if (! rtx_equal_p (XEXP (cond, 1), if_info->b))
1528 else if (rtx_equal_p (XEXP (cond, 1), if_info->a))
1530 if (! rtx_equal_p (XEXP (cond, 0), if_info->b))
1532 code = swap_condition (code);
1537 /* Determine what sort of operation this is. Note that the code is for
1538 a taken branch, so the code->operation mapping appears backwards. */
1571 target = expand_simple_binop (GET_MODE (if_info->x), op,
1572 if_info->a, if_info->b,
1573 if_info->x, unsignedp, OPTAB_WIDEN);
1579 if (target != if_info->x)
1580 noce_emit_move_insn (if_info->x, target);
1583 unshare_ifcvt_sequence (if_info, seq);
1586 if (seq_contains_jump (seq))
1589 emit_insn_before_setloc (seq, if_info->jump, INSN_LOCATOR (if_info->insn_a));
1590 if_info->cond = cond;
1591 if_info->cond_earliest = earliest;
1596 /* Convert "if (a < 0) x = -a; else x = a;" to "x = abs(a);", etc. */
1599 noce_try_abs (struct noce_if_info *if_info)
1601 rtx cond, earliest, target, seq, a, b, c;
1604 /* ??? Can't guarantee that expand_binop won't create pseudos. */
1608 /* Recognize A and B as constituting an ABS or NABS. */
1611 if (GET_CODE (a) == NEG && rtx_equal_p (XEXP (a, 0), b))
1613 else if (GET_CODE (b) == NEG && rtx_equal_p (XEXP (b, 0), a))
1615 c = a; a = b; b = c;
1621 cond = noce_get_alt_condition (if_info, b, &earliest);
1625 /* Verify the condition is of the form we expect. */
1626 if (rtx_equal_p (XEXP (cond, 0), b))
1628 else if (rtx_equal_p (XEXP (cond, 1), b))
1633 /* Verify that C is zero. Search backward through the block for
1634 a REG_EQUAL note if necessary. */
1637 rtx insn, note = NULL;
1638 for (insn = earliest;
1639 insn != BB_HEAD (if_info->test_bb);
1640 insn = PREV_INSN (insn))
1642 && ((note = find_reg_note (insn, REG_EQUAL, c))
1643 || (note = find_reg_note (insn, REG_EQUIV, c))))
1649 if (GET_CODE (c) == MEM
1650 && GET_CODE (XEXP (c, 0)) == SYMBOL_REF
1651 && CONSTANT_POOL_ADDRESS_P (XEXP (c, 0)))
1652 c = get_pool_constant (XEXP (c, 0));
1654 /* Work around funny ideas get_condition has wrt canonicalization.
1655 Note that these rtx constants are known to be CONST_INT, and
1656 therefore imply integer comparisons. */
1657 if (c == constm1_rtx && GET_CODE (cond) == GT)
1659 else if (c == const1_rtx && GET_CODE (cond) == LT)
1661 else if (c != CONST0_RTX (GET_MODE (b)))
1664 /* Determine what sort of operation this is. */
1665 switch (GET_CODE (cond))
1684 target = expand_abs_nojump (GET_MODE (if_info->x), b, if_info->x, 1);
1686 /* ??? It's a quandary whether cmove would be better here, especially
1687 for integers. Perhaps combine will clean things up. */
1688 if (target && negate)
1689 target = expand_simple_unop (GET_MODE (target), NEG, target, if_info->x, 0);
1697 if (target != if_info->x)
1698 noce_emit_move_insn (if_info->x, target);
1701 unshare_ifcvt_sequence (if_info, seq);
1704 if (seq_contains_jump (seq))
1707 emit_insn_before_setloc (seq, if_info->jump, INSN_LOCATOR (if_info->insn_a));
1708 if_info->cond = cond;
1709 if_info->cond_earliest = earliest;
1714 /* Similar to get_condition, only the resulting condition must be
1715 valid at JUMP, instead of at EARLIEST. */
1718 noce_get_condition (rtx jump, rtx *earliest)
1720 rtx cond, set, tmp, insn;
1723 if (! any_condjump_p (jump))
1726 set = pc_set (jump);
1728 /* If this branches to JUMP_LABEL when the condition is false,
1729 reverse the condition. */
1730 reverse = (GET_CODE (XEXP (SET_SRC (set), 2)) == LABEL_REF
1731 && XEXP (XEXP (SET_SRC (set), 2), 0) == JUMP_LABEL (jump));
1733 /* If the condition variable is a register and is MODE_INT, accept it. */
1735 cond = XEXP (SET_SRC (set), 0);
1736 tmp = XEXP (cond, 0);
1737 if (REG_P (tmp) && GET_MODE_CLASS (GET_MODE (tmp)) == MODE_INT)
1742 cond = gen_rtx_fmt_ee (reverse_condition (GET_CODE (cond)),
1743 GET_MODE (cond), tmp, XEXP (cond, 1));
1747 /* Otherwise, fall back on canonicalize_condition to do the dirty
1748 work of manipulating MODE_CC values and COMPARE rtx codes. */
1750 tmp = canonicalize_condition (jump, cond, reverse, earliest, NULL_RTX,
1755 /* We are going to insert code before JUMP, not before EARLIEST.
1756 We must therefore be certain that the given condition is valid
1757 at JUMP by virtue of not having been modified since. */
1758 for (insn = *earliest; insn != jump; insn = NEXT_INSN (insn))
1759 if (INSN_P (insn) && modified_in_p (tmp, insn))
1764 /* The condition was modified. See if we can get a partial result
1765 that doesn't follow all the reversals. Perhaps combine can fold
1766 them together later. */
1767 tmp = XEXP (tmp, 0);
1768 if (!REG_P (tmp) || GET_MODE_CLASS (GET_MODE (tmp)) != MODE_INT)
1770 tmp = canonicalize_condition (jump, cond, reverse, earliest, tmp,
1775 /* For sanity's sake, re-validate the new result. */
1776 for (insn = *earliest; insn != jump; insn = NEXT_INSN (insn))
1777 if (INSN_P (insn) && modified_in_p (tmp, insn))
1783 /* Return true if OP is ok for if-then-else processing. */
1786 noce_operand_ok (rtx op)
1788 /* We special-case memories, so handle any of them with
1789 no address side effects. */
1790 if (GET_CODE (op) == MEM)
1791 return ! side_effects_p (XEXP (op, 0));
1793 if (side_effects_p (op))
1796 return ! may_trap_p (op);
1799 /* Given a simple IF-THEN or IF-THEN-ELSE block, attempt to convert it
1800 without using conditional execution. Return TRUE if we were
1801 successful at converting the block. */
1804 noce_process_if_block (struct ce_if_block * ce_info)
1806 basic_block test_bb = ce_info->test_bb; /* test block */
1807 basic_block then_bb = ce_info->then_bb; /* THEN */
1808 basic_block else_bb = ce_info->else_bb; /* ELSE or NULL */
1809 struct noce_if_info if_info;
1812 rtx orig_x, x, a, b;
1815 /* We're looking for patterns of the form
1817 (1) if (...) x = a; else x = b;
1818 (2) x = b; if (...) x = a;
1819 (3) if (...) x = a; // as if with an initial x = x.
1821 The later patterns require jumps to be more expensive.
1823 ??? For future expansion, look for multiple X in such patterns. */
1825 /* If test is comprised of && or || elements, don't handle it unless it is
1826 the special case of && elements without an ELSE block. */
1827 if (ce_info->num_multiple_test_blocks)
1829 if (else_bb || ! ce_info->and_and_p)
1832 ce_info->test_bb = test_bb = ce_info->last_test_bb;
1833 ce_info->num_multiple_test_blocks = 0;
1834 ce_info->num_and_and_blocks = 0;
1835 ce_info->num_or_or_blocks = 0;
1838 /* If this is not a standard conditional jump, we can't parse it. */
1839 jump = BB_END (test_bb);
1840 cond = noce_get_condition (jump, &if_info.cond_earliest);
1844 /* If the conditional jump is more than just a conditional
1845 jump, then we can not do if-conversion on this block. */
1846 if (! onlyjump_p (jump))
1849 /* We must be comparing objects whose modes imply the size. */
1850 if (GET_MODE (XEXP (cond, 0)) == BLKmode)
1853 /* Look for one of the potential sets. */
1854 insn_a = first_active_insn (then_bb);
1856 || insn_a != last_active_insn (then_bb, FALSE)
1857 || (set_a = single_set (insn_a)) == NULL_RTX)
1860 x = SET_DEST (set_a);
1861 a = SET_SRC (set_a);
1863 /* Look for the other potential set. Make sure we've got equivalent
1865 /* ??? This is overconservative. Storing to two different mems is
1866 as easy as conditionally computing the address. Storing to a
1867 single mem merely requires a scratch memory to use as one of the
1868 destination addresses; often the memory immediately below the
1869 stack pointer is available for this. */
1873 insn_b = first_active_insn (else_bb);
1875 || insn_b != last_active_insn (else_bb, FALSE)
1876 || (set_b = single_set (insn_b)) == NULL_RTX
1877 || ! rtx_equal_p (x, SET_DEST (set_b)))
1882 insn_b = prev_nonnote_insn (if_info.cond_earliest);
1883 /* We're going to be moving the evaluation of B down from above
1884 COND_EARLIEST to JUMP. Make sure the relevant data is still
1887 || GET_CODE (insn_b) != INSN
1888 || (set_b = single_set (insn_b)) == NULL_RTX
1889 || ! rtx_equal_p (x, SET_DEST (set_b))
1890 || reg_overlap_mentioned_p (x, SET_SRC (set_b))
1891 || modified_between_p (SET_SRC (set_b),
1892 PREV_INSN (if_info.cond_earliest), jump)
1893 /* Likewise with X. In particular this can happen when
1894 noce_get_condition looks farther back in the instruction
1895 stream than one might expect. */
1896 || reg_overlap_mentioned_p (x, cond)
1897 || reg_overlap_mentioned_p (x, a)
1898 || modified_between_p (x, PREV_INSN (if_info.cond_earliest), jump))
1899 insn_b = set_b = NULL_RTX;
1902 /* If x has side effects then only the if-then-else form is safe to
1903 convert. But even in that case we would need to restore any notes
1904 (such as REG_INC) at then end. That can be tricky if
1905 noce_emit_move_insn expands to more than one insn, so disable the
1906 optimization entirely for now if there are side effects. */
1907 if (side_effects_p (x))
1910 b = (set_b ? SET_SRC (set_b) : x);
1912 /* Only operate on register destinations, and even then avoid extending
1913 the lifetime of hard registers on small register class machines. */
1915 if (GET_CODE (x) != REG
1916 || (SMALL_REGISTER_CLASSES
1917 && REGNO (x) < FIRST_PSEUDO_REGISTER))
1919 if (no_new_pseudos || GET_MODE (x) == BLKmode)
1921 x = gen_reg_rtx (GET_MODE (GET_CODE (x) == STRICT_LOW_PART
1922 ? XEXP (x, 0) : x));
1925 /* Don't operate on sources that may trap or are volatile. */
1926 if (! noce_operand_ok (a) || ! noce_operand_ok (b))
1929 /* Set up the info block for our subroutines. */
1930 if_info.test_bb = test_bb;
1931 if_info.cond = cond;
1932 if_info.jump = jump;
1933 if_info.insn_a = insn_a;
1934 if_info.insn_b = insn_b;
1939 /* Try optimizations in some approximation of a useful order. */
1940 /* ??? Should first look to see if X is live incoming at all. If it
1941 isn't, we don't need anything but an unconditional set. */
1943 /* Look and see if A and B are really the same. Avoid creating silly
1944 cmove constructs that no one will fix up later. */
1945 if (rtx_equal_p (a, b))
1947 /* If we have an INSN_B, we don't have to create any new rtl. Just
1948 move the instruction that we already have. If we don't have an
1949 INSN_B, that means that A == X, and we've got a noop move. In
1950 that case don't do anything and let the code below delete INSN_A. */
1951 if (insn_b && else_bb)
1955 if (else_bb && insn_b == BB_END (else_bb))
1956 BB_END (else_bb) = PREV_INSN (insn_b);
1957 reorder_insns (insn_b, insn_b, PREV_INSN (jump));
1959 /* If there was a REG_EQUAL note, delete it since it may have been
1960 true due to this insn being after a jump. */
1961 if ((note = find_reg_note (insn_b, REG_EQUAL, NULL_RTX)) != 0)
1962 remove_note (insn_b, note);
1966 /* If we have "x = b; if (...) x = a;", and x has side-effects, then
1967 x must be executed twice. */
1968 else if (insn_b && side_effects_p (orig_x))
1975 /* Disallow the "if (...) x = a;" form (with an implicit "else x = x;")
1976 for most optimizations if writing to x may trap, i.e. its a memory
1977 other than a static var or a stack slot. */
1979 && GET_CODE (orig_x) == MEM
1980 && ! MEM_NOTRAP_P (orig_x)
1981 && rtx_addr_can_trap_p (XEXP (orig_x, 0)))
1983 if (HAVE_conditional_move)
1985 if (noce_try_cmove (&if_info))
1987 if (! HAVE_conditional_execution
1988 && noce_try_cmove_arith (&if_info))
1994 if (noce_try_move (&if_info))
1996 if (noce_try_store_flag (&if_info))
1998 if (noce_try_minmax (&if_info))
2000 if (noce_try_abs (&if_info))
2002 if (HAVE_conditional_move
2003 && noce_try_cmove (&if_info))
2005 if (! HAVE_conditional_execution)
2007 if (noce_try_store_flag_constants (&if_info))
2009 if (noce_try_addcc (&if_info))
2011 if (noce_try_store_flag_mask (&if_info))
2013 if (HAVE_conditional_move
2014 && noce_try_cmove_arith (&if_info))
2021 /* The original sets may now be killed. */
2022 delete_insn (insn_a);
2024 /* Several special cases here: First, we may have reused insn_b above,
2025 in which case insn_b is now NULL. Second, we want to delete insn_b
2026 if it came from the ELSE block, because follows the now correct
2027 write that appears in the TEST block. However, if we got insn_b from
2028 the TEST block, it may in fact be loading data needed for the comparison.
2029 We'll let life_analysis remove the insn if it's really dead. */
2030 if (insn_b && else_bb)
2031 delete_insn (insn_b);
2033 /* The new insns will have been inserted immediately before the jump. We
2034 should be able to remove the jump with impunity, but the condition itself
2035 may have been modified by gcse to be shared across basic blocks. */
2038 /* If we used a temporary, fix it up now. */
2042 noce_emit_move_insn (orig_x, x);
2043 insn_b = get_insns ();
2044 set_used_flags (orig_x);
2045 unshare_all_rtl_in_chain (insn_b);
2048 emit_insn_after_setloc (insn_b, BB_END (test_bb), INSN_LOCATOR (insn_a));
2051 /* Merge the blocks! */
2052 merge_if_block (ce_info);
2057 /* Attempt to convert an IF-THEN or IF-THEN-ELSE block into
2058 straight line code. Return true if successful. */
2061 process_if_block (struct ce_if_block * ce_info)
2063 if (! reload_completed
2064 && noce_process_if_block (ce_info))
2067 if (HAVE_conditional_execution && reload_completed)
2069 /* If we have && and || tests, try to first handle combining the && and
2070 || tests into the conditional code, and if that fails, go back and
2071 handle it without the && and ||, which at present handles the && case
2072 if there was no ELSE block. */
2073 if (cond_exec_process_if_block (ce_info, TRUE))
2076 if (ce_info->num_multiple_test_blocks)
2080 if (cond_exec_process_if_block (ce_info, FALSE))
2088 /* Merge the blocks and mark for local life update. */
2091 merge_if_block (struct ce_if_block * ce_info)
2093 basic_block test_bb = ce_info->test_bb; /* last test block */
2094 basic_block then_bb = ce_info->then_bb; /* THEN */
2095 basic_block else_bb = ce_info->else_bb; /* ELSE or NULL */
2096 basic_block join_bb = ce_info->join_bb; /* join block */
2097 basic_block combo_bb;
2099 /* All block merging is done into the lower block numbers. */
2103 /* Merge any basic blocks to handle && and || subtests. Each of
2104 the blocks are on the fallthru path from the predecessor block. */
2105 if (ce_info->num_multiple_test_blocks > 0)
2107 basic_block bb = test_bb;
2108 basic_block last_test_bb = ce_info->last_test_bb;
2109 basic_block fallthru = block_fallthru (bb);
2114 fallthru = block_fallthru (bb);
2115 if (dom_computed[CDI_POST_DOMINATORS] >= DOM_NO_FAST_QUERY)
2116 delete_from_dominance_info (CDI_POST_DOMINATORS, bb);
2117 merge_blocks (combo_bb, bb);
2120 while (bb != last_test_bb);
2123 /* Merge TEST block into THEN block. Normally the THEN block won't have a
2124 label, but it might if there were || tests. That label's count should be
2125 zero, and it normally should be removed. */
2129 if (combo_bb->global_live_at_end)
2130 COPY_REG_SET (combo_bb->global_live_at_end,
2131 then_bb->global_live_at_end);
2132 if (dom_computed[CDI_POST_DOMINATORS] >= DOM_NO_FAST_QUERY)
2133 delete_from_dominance_info (CDI_POST_DOMINATORS, then_bb);
2134 merge_blocks (combo_bb, then_bb);
2138 /* The ELSE block, if it existed, had a label. That label count
2139 will almost always be zero, but odd things can happen when labels
2140 get their addresses taken. */
2143 if (dom_computed[CDI_POST_DOMINATORS] >= DOM_NO_FAST_QUERY)
2144 delete_from_dominance_info (CDI_POST_DOMINATORS, else_bb);
2145 merge_blocks (combo_bb, else_bb);
2149 /* If there was no join block reported, that means it was not adjacent
2150 to the others, and so we cannot merge them. */
2154 rtx last = BB_END (combo_bb);
2156 /* The outgoing edge for the current COMBO block should already
2157 be correct. Verify this. */
2158 if (combo_bb->succ == NULL_EDGE)
2160 if (find_reg_note (last, REG_NORETURN, NULL))
2162 else if (GET_CODE (last) == INSN
2163 && GET_CODE (PATTERN (last)) == TRAP_IF
2164 && TRAP_CONDITION (PATTERN (last)) == const_true_rtx)
2170 /* There should still be something at the end of the THEN or ELSE
2171 blocks taking us to our final destination. */
2172 else if (GET_CODE (last) == JUMP_INSN)
2174 else if (combo_bb->succ->dest == EXIT_BLOCK_PTR
2175 && GET_CODE (last) == CALL_INSN
2176 && SIBLING_CALL_P (last))
2178 else if ((combo_bb->succ->flags & EDGE_EH)
2179 && can_throw_internal (last))
2185 /* The JOIN block may have had quite a number of other predecessors too.
2186 Since we've already merged the TEST, THEN and ELSE blocks, we should
2187 have only one remaining edge from our if-then-else diamond. If there
2188 is more than one remaining edge, it must come from elsewhere. There
2189 may be zero incoming edges if the THEN block didn't actually join
2190 back up (as with a call to abort). */
2191 else if ((join_bb->pred == NULL
2192 || join_bb->pred->pred_next == NULL)
2193 && join_bb != EXIT_BLOCK_PTR)
2195 /* We can merge the JOIN. */
2196 if (combo_bb->global_live_at_end)
2197 COPY_REG_SET (combo_bb->global_live_at_end,
2198 join_bb->global_live_at_end);
2200 if (dom_computed[CDI_POST_DOMINATORS] >= DOM_NO_FAST_QUERY)
2201 delete_from_dominance_info (CDI_POST_DOMINATORS, join_bb);
2202 merge_blocks (combo_bb, join_bb);
2207 /* We cannot merge the JOIN. */
2209 /* The outgoing edge for the current COMBO block should already
2210 be correct. Verify this. */
2211 if (combo_bb->succ->succ_next != NULL_EDGE
2212 || combo_bb->succ->dest != join_bb)
2215 /* Remove the jump and cruft from the end of the COMBO block. */
2216 if (join_bb != EXIT_BLOCK_PTR)
2217 tidy_fallthru_edge (combo_bb->succ, combo_bb, join_bb);
2220 num_updated_if_blocks++;
2223 /* Find a block ending in a simple IF condition and try to transform it
2224 in some way. When converting a multi-block condition, put the new code
2225 in the first such block and delete the rest. Return a pointer to this
2226 first block if some transformation was done. Return NULL otherwise. */
2229 find_if_header (basic_block test_bb, int pass)
2231 ce_if_block_t ce_info;
2235 /* The kind of block we're looking for has exactly two successors. */
2236 if ((then_edge = test_bb->succ) == NULL_EDGE
2237 || (else_edge = then_edge->succ_next) == NULL_EDGE
2238 || else_edge->succ_next != NULL_EDGE)
2241 /* Neither edge should be abnormal. */
2242 if ((then_edge->flags & EDGE_COMPLEX)
2243 || (else_edge->flags & EDGE_COMPLEX))
2246 /* Nor exit the loop. */
2247 if ((then_edge->flags & EDGE_LOOP_EXIT)
2248 || (else_edge->flags & EDGE_LOOP_EXIT))
2251 /* The THEN edge is canonically the one that falls through. */
2252 if (then_edge->flags & EDGE_FALLTHRU)
2254 else if (else_edge->flags & EDGE_FALLTHRU)
2257 else_edge = then_edge;
2261 /* Otherwise this must be a multiway branch of some sort. */
2264 memset (&ce_info, '\0', sizeof (ce_info));
2265 ce_info.test_bb = test_bb;
2266 ce_info.then_bb = then_edge->dest;
2267 ce_info.else_bb = else_edge->dest;
2268 ce_info.pass = pass;
2270 #ifdef IFCVT_INIT_EXTRA_FIELDS
2271 IFCVT_INIT_EXTRA_FIELDS (&ce_info);
2274 if (find_if_block (&ce_info))
2277 if (HAVE_trap && HAVE_conditional_trap
2278 && find_cond_trap (test_bb, then_edge, else_edge))
2281 if (dom_computed[CDI_POST_DOMINATORS] >= DOM_NO_FAST_QUERY
2282 && (! HAVE_conditional_execution || reload_completed))
2284 if (find_if_case_1 (test_bb, then_edge, else_edge))
2286 if (find_if_case_2 (test_bb, then_edge, else_edge))
2294 fprintf (rtl_dump_file, "Conversion succeeded on pass %d.\n", pass);
2295 return ce_info.test_bb;
2298 /* Return true if a block has two edges, one of which falls through to the next
2299 block, and the other jumps to a specific block, so that we can tell if the
2300 block is part of an && test or an || test. Returns either -1 or the number
2301 of non-note, non-jump, non-USE/CLOBBER insns in the block. */
2304 block_jumps_and_fallthru_p (basic_block cur_bb, basic_block target_bb)
2307 int fallthru_p = FALSE;
2313 if (!cur_bb || !target_bb)
2316 /* If no edges, obviously it doesn't jump or fallthru. */
2317 if (cur_bb->succ == NULL_EDGE)
2320 for (cur_edge = cur_bb->succ;
2321 cur_edge != NULL_EDGE;
2322 cur_edge = cur_edge->succ_next)
2324 if (cur_edge->flags & EDGE_COMPLEX)
2325 /* Anything complex isn't what we want. */
2328 else if (cur_edge->flags & EDGE_FALLTHRU)
2331 else if (cur_edge->dest == target_bb)
2338 if ((jump_p & fallthru_p) == 0)
2341 /* Don't allow calls in the block, since this is used to group && and ||
2342 together for conditional execution support. ??? we should support
2343 conditional execution support across calls for IA-64 some day, but
2344 for now it makes the code simpler. */
2345 end = BB_END (cur_bb);
2346 insn = BB_HEAD (cur_bb);
2348 while (insn != NULL_RTX)
2350 if (GET_CODE (insn) == CALL_INSN)
2354 && GET_CODE (insn) != JUMP_INSN
2355 && GET_CODE (PATTERN (insn)) != USE
2356 && GET_CODE (PATTERN (insn)) != CLOBBER)
2362 insn = NEXT_INSN (insn);
2368 /* Determine if a given basic block heads a simple IF-THEN or IF-THEN-ELSE
2369 block. If so, we'll try to convert the insns to not require the branch.
2370 Return TRUE if we were successful at converting the block. */
2373 find_if_block (struct ce_if_block * ce_info)
2375 basic_block test_bb = ce_info->test_bb;
2376 basic_block then_bb = ce_info->then_bb;
2377 basic_block else_bb = ce_info->else_bb;
2378 basic_block join_bb = NULL_BLOCK;
2379 edge then_succ = then_bb->succ;
2380 edge else_succ = else_bb->succ;
2381 int then_predecessors;
2382 int else_predecessors;
2386 ce_info->last_test_bb = test_bb;
2388 /* Discover if any fall through predecessors of the current test basic block
2389 were && tests (which jump to the else block) or || tests (which jump to
2391 if (HAVE_conditional_execution && reload_completed
2392 && test_bb->pred != NULL_EDGE
2393 && test_bb->pred->pred_next == NULL_EDGE
2394 && test_bb->pred->flags == EDGE_FALLTHRU)
2396 basic_block bb = test_bb->pred->src;
2397 basic_block target_bb;
2398 int max_insns = MAX_CONDITIONAL_EXECUTE;
2401 /* Determine if the preceding block is an && or || block. */
2402 if ((n_insns = block_jumps_and_fallthru_p (bb, else_bb)) >= 0)
2404 ce_info->and_and_p = TRUE;
2405 target_bb = else_bb;
2407 else if ((n_insns = block_jumps_and_fallthru_p (bb, then_bb)) >= 0)
2409 ce_info->and_and_p = FALSE;
2410 target_bb = then_bb;
2413 target_bb = NULL_BLOCK;
2415 if (target_bb && n_insns <= max_insns)
2417 int total_insns = 0;
2420 ce_info->last_test_bb = test_bb;
2422 /* Found at least one && or || block, look for more. */
2425 ce_info->test_bb = test_bb = bb;
2426 total_insns += n_insns;
2429 if (bb->pred == NULL_EDGE || bb->pred->pred_next != NULL_EDGE)
2433 n_insns = block_jumps_and_fallthru_p (bb, target_bb);
2435 while (n_insns >= 0 && (total_insns + n_insns) <= max_insns);
2437 ce_info->num_multiple_test_blocks = blocks;
2438 ce_info->num_multiple_test_insns = total_insns;
2440 if (ce_info->and_and_p)
2441 ce_info->num_and_and_blocks = blocks;
2443 ce_info->num_or_or_blocks = blocks;
2447 /* Count the number of edges the THEN and ELSE blocks have. */
2448 then_predecessors = 0;
2449 for (cur_edge = then_bb->pred;
2450 cur_edge != NULL_EDGE;
2451 cur_edge = cur_edge->pred_next)
2453 then_predecessors++;
2454 if (cur_edge->flags & EDGE_COMPLEX)
2458 else_predecessors = 0;
2459 for (cur_edge = else_bb->pred;
2460 cur_edge != NULL_EDGE;
2461 cur_edge = cur_edge->pred_next)
2463 else_predecessors++;
2464 if (cur_edge->flags & EDGE_COMPLEX)
2468 /* The THEN block of an IF-THEN combo must have exactly one predecessor,
2469 other than any || blocks which jump to the THEN block. */
2470 if ((then_predecessors - ce_info->num_or_or_blocks) != 1)
2473 /* The THEN block of an IF-THEN combo must have zero or one successors. */
2474 if (then_succ != NULL_EDGE
2475 && (then_succ->succ_next != NULL_EDGE
2476 || (then_succ->flags & EDGE_COMPLEX)
2477 || (flow2_completed && tablejump_p (BB_END (then_bb), NULL, NULL))))
2480 /* If the THEN block has no successors, conditional execution can still
2481 make a conditional call. Don't do this unless the ELSE block has
2482 only one incoming edge -- the CFG manipulation is too ugly otherwise.
2483 Check for the last insn of the THEN block being an indirect jump, which
2484 is listed as not having any successors, but confuses the rest of the CE
2485 code processing. ??? we should fix this in the future. */
2486 if (then_succ == NULL)
2488 if (else_bb->pred->pred_next == NULL_EDGE)
2490 rtx last_insn = BB_END (then_bb);
2493 && GET_CODE (last_insn) == NOTE
2494 && last_insn != BB_HEAD (then_bb))
2495 last_insn = PREV_INSN (last_insn);
2498 && GET_CODE (last_insn) == JUMP_INSN
2499 && ! simplejump_p (last_insn))
2503 else_bb = NULL_BLOCK;
2509 /* If the THEN block's successor is the other edge out of the TEST block,
2510 then we have an IF-THEN combo without an ELSE. */
2511 else if (then_succ->dest == else_bb)
2514 else_bb = NULL_BLOCK;
2517 /* If the THEN and ELSE block meet in a subsequent block, and the ELSE
2518 has exactly one predecessor and one successor, and the outgoing edge
2519 is not complex, then we have an IF-THEN-ELSE combo. */
2520 else if (else_succ != NULL_EDGE
2521 && then_succ->dest == else_succ->dest
2522 && else_bb->pred->pred_next == NULL_EDGE
2523 && else_succ->succ_next == NULL_EDGE
2524 && ! (else_succ->flags & EDGE_COMPLEX)
2525 && ! (flow2_completed && tablejump_p (BB_END (else_bb), NULL, NULL)))
2526 join_bb = else_succ->dest;
2528 /* Otherwise it is not an IF-THEN or IF-THEN-ELSE combination. */
2532 num_possible_if_blocks++;
2536 fprintf (rtl_dump_file, "\nIF-THEN%s block found, pass %d, start block %d [insn %d], then %d [%d]",
2537 (else_bb) ? "-ELSE" : "",
2539 test_bb->index, (BB_HEAD (test_bb)) ? (int)INSN_UID (BB_HEAD (test_bb)) : -1,
2540 then_bb->index, (BB_HEAD (then_bb)) ? (int)INSN_UID (BB_HEAD (then_bb)) : -1);
2543 fprintf (rtl_dump_file, ", else %d [%d]",
2544 else_bb->index, (BB_HEAD (else_bb)) ? (int)INSN_UID (BB_HEAD (else_bb)) : -1);
2546 fprintf (rtl_dump_file, ", join %d [%d]",
2547 join_bb->index, (BB_HEAD (join_bb)) ? (int)INSN_UID (BB_HEAD (join_bb)) : -1);
2549 if (ce_info->num_multiple_test_blocks > 0)
2550 fprintf (rtl_dump_file, ", %d %s block%s last test %d [%d]",
2551 ce_info->num_multiple_test_blocks,
2552 (ce_info->and_and_p) ? "&&" : "||",
2553 (ce_info->num_multiple_test_blocks == 1) ? "" : "s",
2554 ce_info->last_test_bb->index,
2555 ((BB_HEAD (ce_info->last_test_bb))
2556 ? (int)INSN_UID (BB_HEAD (ce_info->last_test_bb))
2559 fputc ('\n', rtl_dump_file);
2562 /* Make sure IF, THEN, and ELSE, blocks are adjacent. Actually, we get the
2563 first condition for free, since we've already asserted that there's a
2564 fallthru edge from IF to THEN. Likewise for the && and || blocks, since
2565 we checked the FALLTHRU flag, those are already adjacent to the last IF
2567 /* ??? As an enhancement, move the ELSE block. Have to deal with
2568 BLOCK notes, if by no other means than aborting the merge if they
2569 exist. Sticky enough I don't want to think about it now. */
2571 if (else_bb && (next = next->next_bb) != else_bb)
2573 if ((next = next->next_bb) != join_bb && join_bb != EXIT_BLOCK_PTR)
2581 /* Do the real work. */
2582 ce_info->else_bb = else_bb;
2583 ce_info->join_bb = join_bb;
2585 return process_if_block (ce_info);
2588 /* Convert a branch over a trap, or a branch
2589 to a trap, into a conditional trap. */
2592 find_cond_trap (basic_block test_bb, edge then_edge, edge else_edge)
2594 basic_block then_bb = then_edge->dest;
2595 basic_block else_bb = else_edge->dest;
2596 basic_block other_bb, trap_bb;
2597 rtx trap, jump, cond, cond_earliest, seq;
2600 /* Locate the block with the trap instruction. */
2601 /* ??? While we look for no successors, we really ought to allow
2602 EH successors. Need to fix merge_if_block for that to work. */
2603 if ((trap = block_has_only_trap (then_bb)) != NULL)
2604 trap_bb = then_bb, other_bb = else_bb;
2605 else if ((trap = block_has_only_trap (else_bb)) != NULL)
2606 trap_bb = else_bb, other_bb = then_bb;
2612 fprintf (rtl_dump_file, "\nTRAP-IF block found, start %d, trap %d\n",
2613 test_bb->index, trap_bb->index);
2616 /* If this is not a standard conditional jump, we can't parse it. */
2617 jump = BB_END (test_bb);
2618 cond = noce_get_condition (jump, &cond_earliest);
2622 /* If the conditional jump is more than just a conditional jump, then
2623 we can not do if-conversion on this block. */
2624 if (! onlyjump_p (jump))
2627 /* We must be comparing objects whose modes imply the size. */
2628 if (GET_MODE (XEXP (cond, 0)) == BLKmode)
2631 /* Reverse the comparison code, if necessary. */
2632 code = GET_CODE (cond);
2633 if (then_bb == trap_bb)
2635 code = reversed_comparison_code (cond, jump);
2636 if (code == UNKNOWN)
2640 /* Attempt to generate the conditional trap. */
2641 seq = gen_cond_trap (code, XEXP (cond, 0),
2643 TRAP_CODE (PATTERN (trap)));
2649 /* Emit the new insns before cond_earliest. */
2650 emit_insn_before_setloc (seq, cond_earliest, INSN_LOCATOR (trap));
2652 /* Delete the trap block if possible. */
2653 remove_edge (trap_bb == then_bb ? then_edge : else_edge);
2654 if (trap_bb->pred == NULL)
2656 if (dom_computed[CDI_POST_DOMINATORS] >= DOM_NO_FAST_QUERY)
2657 delete_from_dominance_info (CDI_POST_DOMINATORS, trap_bb);
2658 delete_block (trap_bb);
2661 /* If the non-trap block and the test are now adjacent, merge them.
2662 Otherwise we must insert a direct branch. */
2663 if (test_bb->next_bb == other_bb)
2665 struct ce_if_block new_ce_info;
2667 memset (&new_ce_info, '\0', sizeof (new_ce_info));
2668 new_ce_info.test_bb = test_bb;
2669 new_ce_info.then_bb = NULL;
2670 new_ce_info.else_bb = NULL;
2671 new_ce_info.join_bb = other_bb;
2672 merge_if_block (&new_ce_info);
2678 lab = JUMP_LABEL (jump);
2679 newjump = emit_jump_insn_after (gen_jump (lab), jump);
2680 LABEL_NUSES (lab) += 1;
2681 JUMP_LABEL (newjump) = lab;
2682 emit_barrier_after (newjump);
2690 /* Subroutine of find_cond_trap: if BB contains only a trap insn,
2694 block_has_only_trap (basic_block bb)
2698 /* We're not the exit block. */
2699 if (bb == EXIT_BLOCK_PTR)
2702 /* The block must have no successors. */
2706 /* The only instruction in the THEN block must be the trap. */
2707 trap = first_active_insn (bb);
2708 if (! (trap == BB_END (bb)
2709 && GET_CODE (PATTERN (trap)) == TRAP_IF
2710 && TRAP_CONDITION (PATTERN (trap)) == const_true_rtx))
2716 /* Look for IF-THEN-ELSE cases in which one of THEN or ELSE is
2717 transformable, but not necessarily the other. There need be no
2720 Return TRUE if we were successful at converting the block.
2722 Cases we'd like to look at:
2725 if (test) goto over; // x not live
2733 if (! test) goto label;
2736 if (test) goto E; // x not live
2750 (3) // This one's really only interesting for targets that can do
2751 // multiway branching, e.g. IA-64 BBB bundles. For other targets
2752 // it results in multiple branches on a cache line, which often
2753 // does not sit well with predictors.
2755 if (test1) goto E; // predicted not taken
2771 (A) Don't do (2) if the branch is predicted against the block we're
2772 eliminating. Do it anyway if we can eliminate a branch; this requires
2773 that the sole successor of the eliminated block postdominate the other
2776 (B) With CE, on (3) we can steal from both sides of the if, creating
2785 Again, this is most useful if J postdominates.
2787 (C) CE substitutes for helpful life information.
2789 (D) These heuristics need a lot of work. */
2791 /* Tests for case 1 above. */
2794 find_if_case_1 (basic_block test_bb, edge then_edge, edge else_edge)
2796 basic_block then_bb = then_edge->dest;
2797 basic_block else_bb = else_edge->dest, new_bb;
2798 edge then_succ = then_bb->succ;
2801 /* THEN has one successor. */
2802 if (!then_succ || then_succ->succ_next != NULL)
2805 /* THEN does not fall through, but is not strange either. */
2806 if (then_succ->flags & (EDGE_COMPLEX | EDGE_FALLTHRU))
2809 /* THEN has one predecessor. */
2810 if (then_bb->pred->pred_next != NULL)
2813 /* THEN must do something. */
2814 if (forwarder_block_p (then_bb))
2817 num_possible_if_blocks++;
2819 fprintf (rtl_dump_file,
2820 "\nIF-CASE-1 found, start %d, then %d\n",
2821 test_bb->index, then_bb->index);
2823 /* THEN is small. */
2824 if (count_bb_insns (then_bb) > BRANCH_COST)
2827 /* Registers set are dead, or are predicable. */
2828 if (! dead_or_predicable (test_bb, then_bb, else_bb,
2829 then_bb->succ->dest, 1))
2832 /* Conversion went ok, including moving the insns and fixing up the
2833 jump. Adjust the CFG to match. */
2835 bitmap_operation (test_bb->global_live_at_end,
2836 else_bb->global_live_at_start,
2837 then_bb->global_live_at_end, BITMAP_IOR);
2839 new_bb = redirect_edge_and_branch_force (FALLTHRU_EDGE (test_bb), else_bb);
2840 then_bb_index = then_bb->index;
2841 if (dom_computed[CDI_POST_DOMINATORS] >= DOM_NO_FAST_QUERY)
2842 delete_from_dominance_info (CDI_POST_DOMINATORS, then_bb);
2843 delete_block (then_bb);
2845 /* Make rest of code believe that the newly created block is the THEN_BB
2846 block we removed. */
2849 new_bb->index = then_bb_index;
2850 BASIC_BLOCK (then_bb_index) = new_bb;
2851 if (dom_computed[CDI_POST_DOMINATORS] >= DOM_NO_FAST_QUERY)
2852 add_to_dominance_info (CDI_POST_DOMINATORS, new_bb);
2854 /* We've possibly created jump to next insn, cleanup_cfg will solve that
2858 num_updated_if_blocks++;
2863 /* Test for case 2 above. */
2866 find_if_case_2 (basic_block test_bb, edge then_edge, edge else_edge)
2868 basic_block then_bb = then_edge->dest;
2869 basic_block else_bb = else_edge->dest;
2870 edge else_succ = else_bb->succ;
2873 /* ELSE has one successor. */
2874 if (!else_succ || else_succ->succ_next != NULL)
2877 /* ELSE outgoing edge is not complex. */
2878 if (else_succ->flags & EDGE_COMPLEX)
2881 /* ELSE has one predecessor. */
2882 if (else_bb->pred->pred_next != NULL)
2885 /* THEN is not EXIT. */
2886 if (then_bb->index < 0)
2889 /* ELSE is predicted or SUCC(ELSE) postdominates THEN. */
2890 note = find_reg_note (BB_END (test_bb), REG_BR_PROB, NULL_RTX);
2891 if (note && INTVAL (XEXP (note, 0)) >= REG_BR_PROB_BASE / 2)
2893 else if (else_succ->dest->index < 0
2894 || dominated_by_p (CDI_POST_DOMINATORS, then_bb,
2900 num_possible_if_blocks++;
2902 fprintf (rtl_dump_file,
2903 "\nIF-CASE-2 found, start %d, else %d\n",
2904 test_bb->index, else_bb->index);
2906 /* ELSE is small. */
2907 if (count_bb_insns (else_bb) > BRANCH_COST)
2910 /* Registers set are dead, or are predicable. */
2911 if (! dead_or_predicable (test_bb, else_bb, then_bb, else_succ->dest, 0))
2914 /* Conversion went ok, including moving the insns and fixing up the
2915 jump. Adjust the CFG to match. */
2917 bitmap_operation (test_bb->global_live_at_end,
2918 then_bb->global_live_at_start,
2919 else_bb->global_live_at_end, BITMAP_IOR);
2921 if (dom_computed[CDI_POST_DOMINATORS] >= DOM_NO_FAST_QUERY)
2922 delete_from_dominance_info (CDI_POST_DOMINATORS, else_bb);
2923 delete_block (else_bb);
2926 num_updated_if_blocks++;
2928 /* ??? We may now fallthru from one of THEN's successors into a join
2929 block. Rerun cleanup_cfg? Examine things manually? Wait? */
2934 /* A subroutine of dead_or_predicable called through for_each_rtx.
2935 Return 1 if a memory is found. */
2938 find_memory (rtx *px, void *data ATTRIBUTE_UNUSED)
2940 return GET_CODE (*px) == MEM;
2943 /* Used by the code above to perform the actual rtl transformations.
2944 Return TRUE if successful.
2946 TEST_BB is the block containing the conditional branch. MERGE_BB
2947 is the block containing the code to manipulate. NEW_DEST is the
2948 label TEST_BB should be branching to after the conversion.
2949 REVERSEP is true if the sense of the branch should be reversed. */
2952 dead_or_predicable (basic_block test_bb, basic_block merge_bb,
2953 basic_block other_bb, basic_block new_dest, int reversep)
2955 rtx head, end, jump, earliest, old_dest, new_label = NULL_RTX;
2957 jump = BB_END (test_bb);
2959 /* Find the extent of the real code in the merge block. */
2960 head = BB_HEAD (merge_bb);
2961 end = BB_END (merge_bb);
2963 if (GET_CODE (head) == CODE_LABEL)
2964 head = NEXT_INSN (head);
2965 if (GET_CODE (head) == NOTE)
2969 head = end = NULL_RTX;
2972 head = NEXT_INSN (head);
2975 if (GET_CODE (end) == JUMP_INSN)
2979 head = end = NULL_RTX;
2982 end = PREV_INSN (end);
2985 /* Disable handling dead code by conditional execution if the machine needs
2986 to do anything funny with the tests, etc. */
2987 #ifndef IFCVT_MODIFY_TESTS
2988 if (HAVE_conditional_execution)
2990 /* In the conditional execution case, we have things easy. We know
2991 the condition is reversible. We don't have to check life info
2992 because we're going to conditionally execute the code anyway.
2993 All that's left is making sure the insns involved can actually
2998 cond = cond_exec_get_condition (jump);
3002 prob_val = find_reg_note (jump, REG_BR_PROB, NULL_RTX);
3004 prob_val = XEXP (prob_val, 0);
3008 enum rtx_code rev = reversed_comparison_code (cond, jump);
3011 cond = gen_rtx_fmt_ee (rev, GET_MODE (cond), XEXP (cond, 0),
3014 prob_val = GEN_INT (REG_BR_PROB_BASE - INTVAL (prob_val));
3017 if (! cond_exec_process_insns ((ce_if_block_t *)0, head, end, cond,
3026 /* In the non-conditional execution case, we have to verify that there
3027 are no trapping operations, no calls, no references to memory, and
3028 that any registers modified are dead at the branch site. */
3030 rtx insn, cond, prev;
3031 regset_head merge_set_head, tmp_head, test_live_head, test_set_head;
3032 regset merge_set, tmp, test_live, test_set;
3033 struct propagate_block_info *pbi;
3036 /* Check for no calls or trapping operations. */
3037 for (insn = head; ; insn = NEXT_INSN (insn))
3039 if (GET_CODE (insn) == CALL_INSN)
3043 if (may_trap_p (PATTERN (insn)))
3046 /* ??? Even non-trapping memories such as stack frame
3047 references must be avoided. For stores, we collect
3048 no lifetime info; for reads, we'd have to assert
3049 true_dependence false against every store in the
3051 if (for_each_rtx (&PATTERN (insn), find_memory, NULL))
3058 if (! any_condjump_p (jump))
3061 /* Find the extent of the conditional. */
3062 cond = noce_get_condition (jump, &earliest);
3067 MERGE_SET = set of registers set in MERGE_BB
3068 TEST_LIVE = set of registers live at EARLIEST
3069 TEST_SET = set of registers set between EARLIEST and the
3070 end of the block. */
3072 tmp = INITIALIZE_REG_SET (tmp_head);
3073 merge_set = INITIALIZE_REG_SET (merge_set_head);
3074 test_live = INITIALIZE_REG_SET (test_live_head);
3075 test_set = INITIALIZE_REG_SET (test_set_head);
3077 /* ??? bb->local_set is only valid during calculate_global_regs_live,
3078 so we must recompute usage for MERGE_BB. Not so bad, I suppose,
3079 since we've already asserted that MERGE_BB is small. */
3080 propagate_block (merge_bb, tmp, merge_set, merge_set, 0);
3082 /* For small register class machines, don't lengthen lifetimes of
3083 hard registers before reload. */
3084 if (SMALL_REGISTER_CLASSES && ! reload_completed)
3086 EXECUTE_IF_SET_IN_BITMAP
3089 if (i < FIRST_PSEUDO_REGISTER
3091 && ! global_regs[i])
3096 /* For TEST, we're interested in a range of insns, not a whole block.
3097 Moreover, we're interested in the insns live from OTHER_BB. */
3099 COPY_REG_SET (test_live, other_bb->global_live_at_start);
3100 pbi = init_propagate_block_info (test_bb, test_live, test_set, test_set,
3103 for (insn = jump; ; insn = prev)
3105 prev = propagate_one_insn (pbi, insn);
3106 if (insn == earliest)
3110 free_propagate_block_info (pbi);
3112 /* We can perform the transformation if
3113 MERGE_SET & (TEST_SET | TEST_LIVE)
3115 TEST_SET & merge_bb->global_live_at_start
3118 bitmap_operation (tmp, test_set, test_live, BITMAP_IOR);
3119 bitmap_operation (tmp, tmp, merge_set, BITMAP_AND);
3120 EXECUTE_IF_SET_IN_BITMAP(tmp, 0, i, fail = 1);
3122 bitmap_operation (tmp, test_set, merge_bb->global_live_at_start,
3124 EXECUTE_IF_SET_IN_BITMAP(tmp, 0, i, fail = 1);
3127 FREE_REG_SET (merge_set);
3128 FREE_REG_SET (test_live);
3129 FREE_REG_SET (test_set);
3136 /* We don't want to use normal invert_jump or redirect_jump because
3137 we don't want to delete_insn called. Also, we want to do our own
3138 change group management. */
3140 old_dest = JUMP_LABEL (jump);
3141 if (other_bb != new_dest)
3143 new_label = block_label (new_dest);
3145 ? ! invert_jump_1 (jump, new_label)
3146 : ! redirect_jump_1 (jump, new_label))
3150 if (! apply_change_group ())
3153 if (other_bb != new_dest)
3156 LABEL_NUSES (old_dest) -= 1;
3158 LABEL_NUSES (new_label) += 1;
3159 JUMP_LABEL (jump) = new_label;
3161 invert_br_probabilities (jump);
3163 redirect_edge_succ (BRANCH_EDGE (test_bb), new_dest);
3166 gcov_type count, probability;
3167 count = BRANCH_EDGE (test_bb)->count;
3168 BRANCH_EDGE (test_bb)->count = FALLTHRU_EDGE (test_bb)->count;
3169 FALLTHRU_EDGE (test_bb)->count = count;
3170 probability = BRANCH_EDGE (test_bb)->probability;
3171 BRANCH_EDGE (test_bb)->probability
3172 = FALLTHRU_EDGE (test_bb)->probability;
3173 FALLTHRU_EDGE (test_bb)->probability = probability;
3174 update_br_prob_note (test_bb);
3178 /* Move the insns out of MERGE_BB to before the branch. */
3181 if (end == BB_END (merge_bb))
3182 BB_END (merge_bb) = PREV_INSN (head);
3184 if (squeeze_notes (&head, &end))
3187 reorder_insns (head, end, PREV_INSN (earliest));
3190 /* Remove the jump and edge if we can. */
3191 if (other_bb == new_dest)
3194 remove_edge (BRANCH_EDGE (test_bb));
3195 /* ??? Can't merge blocks here, as then_bb is still in use.
3196 At minimum, the merge will get done just before bb-reorder. */
3206 /* Main entry point for all if-conversion. */
3209 if_convert (int x_life_data_ok)
3214 num_possible_if_blocks = 0;
3215 num_updated_if_blocks = 0;
3216 num_true_changes = 0;
3217 life_data_ok = (x_life_data_ok != 0);
3219 if (! (* targetm.cannot_modify_jumps_p) ())
3220 mark_loop_exit_edges ();
3222 /* Free up basic_block_for_insn so that we don't have to keep it
3223 up to date, either here or in merge_blocks. */
3224 free_basic_block_vars (1);
3226 /* Compute postdominators if we think we'll use them. */
3227 if (HAVE_conditional_execution || life_data_ok)
3228 calculate_dominance_info (CDI_POST_DOMINATORS);
3233 /* Go through each of the basic blocks looking for things to convert. If we
3234 have conditional execution, we make multiple passes to allow us to handle
3235 IF-THEN{-ELSE} blocks within other IF-THEN{-ELSE} blocks. */
3239 cond_exec_changed_p = FALSE;
3242 #ifdef IFCVT_MULTIPLE_DUMPS
3243 if (rtl_dump_file && pass > 1)
3244 fprintf (rtl_dump_file, "\n\n========== Pass %d ==========\n", pass);
3250 while ((new_bb = find_if_header (bb, pass)))
3254 #ifdef IFCVT_MULTIPLE_DUMPS
3255 if (rtl_dump_file && cond_exec_changed_p)
3256 print_rtl_with_bb (rtl_dump_file, get_insns ());
3259 while (cond_exec_changed_p);
3261 #ifdef IFCVT_MULTIPLE_DUMPS
3263 fprintf (rtl_dump_file, "\n\n========== no more changes\n");
3266 free_dominance_info (CDI_POST_DOMINATORS);
3269 fflush (rtl_dump_file);
3271 clear_aux_for_blocks ();
3273 /* Rebuild life info for basic blocks that require it. */
3274 if (num_true_changes && life_data_ok)
3276 /* If we allocated new pseudos, we must resize the array for sched1. */
3277 if (max_regno < max_reg_num ())
3279 max_regno = max_reg_num ();
3280 allocate_reg_info (max_regno, FALSE, FALSE);
3282 update_life_info_in_dirty_blocks (UPDATE_LIFE_GLOBAL_RM_NOTES,
3283 PROP_DEATH_NOTES | PROP_SCAN_DEAD_CODE
3284 | PROP_KILL_DEAD_CODE);
3287 /* Write the final stats. */
3288 if (rtl_dump_file && num_possible_if_blocks > 0)
3290 fprintf (rtl_dump_file,
3291 "\n%d possible IF blocks searched.\n",
3292 num_possible_if_blocks);
3293 fprintf (rtl_dump_file,
3294 "%d IF blocks converted.\n",
3295 num_updated_if_blocks);
3296 fprintf (rtl_dump_file,
3297 "%d true changes made.\n\n\n",
3301 #ifdef ENABLE_CHECKING
3302 verify_flow_info ();