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)
1202 /* A conditional move from two memory sources is equivalent to a
1203 conditional on their addresses followed by a load. Don't do this
1204 early because it'll screw alias analysis. Note that we've
1205 already checked for no side effects. */
1206 if (! no_new_pseudos && cse_not_expected
1207 && GET_CODE (a) == MEM && GET_CODE (b) == MEM
1208 && BRANCH_COST >= 5)
1212 x = gen_reg_rtx (Pmode);
1216 /* ??? We could handle this if we knew that a load from A or B could
1217 not fault. This is also true if we've already loaded
1218 from the address along the path from ENTRY. */
1219 else if (may_trap_p (a) || may_trap_p (b))
1222 /* if (test) x = a + b; else x = c - d;
1229 code = GET_CODE (if_info->cond);
1230 insn_a = if_info->insn_a;
1231 insn_b = if_info->insn_b;
1233 /* Possibly rearrange operands to make things come out more natural. */
1234 if (reversed_comparison_code (if_info->cond, if_info->jump) != UNKNOWN)
1237 if (rtx_equal_p (b, x))
1239 else if (general_operand (b, GET_MODE (b)))
1244 code = reversed_comparison_code (if_info->cond, if_info->jump);
1245 tmp = a, a = b, b = tmp;
1246 tmp = insn_a, insn_a = insn_b, insn_b = tmp;
1255 /* If either operand is complex, load it into a register first.
1256 The best way to do this is to copy the original insn. In this
1257 way we preserve any clobbers etc that the insn may have had.
1258 This is of course not possible in the IS_MEM case. */
1259 if (! general_operand (a, GET_MODE (a)))
1264 goto end_seq_and_fail;
1268 tmp = gen_reg_rtx (GET_MODE (a));
1269 tmp = emit_insn (gen_rtx_SET (VOIDmode, tmp, a));
1272 goto end_seq_and_fail;
1275 a = gen_reg_rtx (GET_MODE (a));
1276 tmp = copy_rtx (insn_a);
1277 set = single_set (tmp);
1279 tmp = emit_insn (PATTERN (tmp));
1281 if (recog_memoized (tmp) < 0)
1282 goto end_seq_and_fail;
1284 if (! general_operand (b, GET_MODE (b)))
1289 goto end_seq_and_fail;
1293 tmp = gen_reg_rtx (GET_MODE (b));
1294 tmp = gen_rtx_SET (VOIDmode, tmp, b);
1297 goto end_seq_and_fail;
1300 b = gen_reg_rtx (GET_MODE (b));
1301 tmp = copy_rtx (insn_b);
1302 set = single_set (tmp);
1304 tmp = PATTERN (tmp);
1307 /* If insn to set up A clobbers any registers B depends on, try to
1308 swap insn that sets up A with the one that sets up B. If even
1309 that doesn't help, punt. */
1310 last = get_last_insn ();
1311 if (last && modified_in_p (orig_b, last))
1313 tmp = emit_insn_before (tmp, get_insns ());
1314 if (modified_in_p (orig_a, tmp))
1315 goto end_seq_and_fail;
1318 tmp = emit_insn (tmp);
1320 if (recog_memoized (tmp) < 0)
1321 goto end_seq_and_fail;
1324 target = noce_emit_cmove (if_info, x, code, XEXP (if_info->cond, 0),
1325 XEXP (if_info->cond, 1), a, b);
1328 goto end_seq_and_fail;
1330 /* If we're handling a memory for above, emit the load now. */
1333 tmp = gen_rtx_MEM (GET_MODE (if_info->x), target);
1335 /* Copy over flags as appropriate. */
1336 if (MEM_VOLATILE_P (if_info->a) || MEM_VOLATILE_P (if_info->b))
1337 MEM_VOLATILE_P (tmp) = 1;
1338 if (MEM_IN_STRUCT_P (if_info->a) && MEM_IN_STRUCT_P (if_info->b))
1339 MEM_IN_STRUCT_P (tmp) = 1;
1340 if (MEM_SCALAR_P (if_info->a) && MEM_SCALAR_P (if_info->b))
1341 MEM_SCALAR_P (tmp) = 1;
1342 if (MEM_ALIAS_SET (if_info->a) == MEM_ALIAS_SET (if_info->b))
1343 set_mem_alias_set (tmp, MEM_ALIAS_SET (if_info->a));
1345 MIN (MEM_ALIGN (if_info->a), MEM_ALIGN (if_info->b)));
1347 noce_emit_move_insn (if_info->x, tmp);
1349 else if (target != x)
1350 noce_emit_move_insn (x, target);
1353 unshare_ifcvt_sequence (if_info, tmp);
1355 emit_insn_before_setloc (tmp, if_info->jump, INSN_LOCATOR (if_info->insn_a));
1363 /* For most cases, the simplified condition we found is the best
1364 choice, but this is not the case for the min/max/abs transforms.
1365 For these we wish to know that it is A or B in the condition. */
1368 noce_get_alt_condition (struct noce_if_info *if_info, rtx target,
1371 rtx cond, set, insn;
1374 /* If target is already mentioned in the known condition, return it. */
1375 if (reg_mentioned_p (target, if_info->cond))
1377 *earliest = if_info->cond_earliest;
1378 return if_info->cond;
1381 set = pc_set (if_info->jump);
1382 cond = XEXP (SET_SRC (set), 0);
1384 = GET_CODE (XEXP (SET_SRC (set), 2)) == LABEL_REF
1385 && XEXP (XEXP (SET_SRC (set), 2), 0) == JUMP_LABEL (if_info->jump);
1387 /* If we're looking for a constant, try to make the conditional
1388 have that constant in it. There are two reasons why it may
1389 not have the constant we want:
1391 1. GCC may have needed to put the constant in a register, because
1392 the target can't compare directly against that constant. For
1393 this case, we look for a SET immediately before the comparison
1394 that puts a constant in that register.
1396 2. GCC may have canonicalized the conditional, for example
1397 replacing "if x < 4" with "if x <= 3". We can undo that (or
1398 make equivalent types of changes) to get the constants we need
1399 if they're off by one in the right direction. */
1401 if (GET_CODE (target) == CONST_INT)
1403 enum rtx_code code = GET_CODE (if_info->cond);
1404 rtx op_a = XEXP (if_info->cond, 0);
1405 rtx op_b = XEXP (if_info->cond, 1);
1408 /* First, look to see if we put a constant in a register. */
1409 prev_insn = PREV_INSN (if_info->cond_earliest);
1411 && INSN_P (prev_insn)
1412 && GET_CODE (PATTERN (prev_insn)) == SET)
1414 rtx src = find_reg_equal_equiv_note (prev_insn);
1416 src = SET_SRC (PATTERN (prev_insn));
1417 if (GET_CODE (src) == CONST_INT)
1419 if (rtx_equal_p (op_a, SET_DEST (PATTERN (prev_insn))))
1421 else if (rtx_equal_p (op_b, SET_DEST (PATTERN (prev_insn))))
1424 if (GET_CODE (op_a) == CONST_INT)
1429 code = swap_condition (code);
1434 /* Now, look to see if we can get the right constant by
1435 adjusting the conditional. */
1436 if (GET_CODE (op_b) == CONST_INT)
1438 HOST_WIDE_INT desired_val = INTVAL (target);
1439 HOST_WIDE_INT actual_val = INTVAL (op_b);
1444 if (actual_val == desired_val + 1)
1447 op_b = GEN_INT (desired_val);
1451 if (actual_val == desired_val - 1)
1454 op_b = GEN_INT (desired_val);
1458 if (actual_val == desired_val - 1)
1461 op_b = GEN_INT (desired_val);
1465 if (actual_val == desired_val + 1)
1468 op_b = GEN_INT (desired_val);
1476 /* If we made any changes, generate a new conditional that is
1477 equivalent to what we started with, but has the right
1479 if (code != GET_CODE (if_info->cond)
1480 || op_a != XEXP (if_info->cond, 0)
1481 || op_b != XEXP (if_info->cond, 1))
1483 cond = gen_rtx_fmt_ee (code, GET_MODE (cond), op_a, op_b);
1484 *earliest = if_info->cond_earliest;
1489 cond = canonicalize_condition (if_info->jump, cond, reverse,
1490 earliest, target, false);
1491 if (! cond || ! reg_mentioned_p (target, cond))
1494 /* We almost certainly searched back to a different place.
1495 Need to re-verify correct lifetimes. */
1497 /* X may not be mentioned in the range (cond_earliest, jump]. */
1498 for (insn = if_info->jump; insn != *earliest; insn = PREV_INSN (insn))
1499 if (INSN_P (insn) && reg_overlap_mentioned_p (if_info->x, PATTERN (insn)))
1502 /* A and B may not be modified in the range [cond_earliest, jump). */
1503 for (insn = *earliest; insn != if_info->jump; insn = NEXT_INSN (insn))
1505 && (modified_in_p (if_info->a, insn)
1506 || modified_in_p (if_info->b, insn)))
1512 /* Convert "if (a < b) x = a; else x = b;" to "x = min(a, b);", etc. */
1515 noce_try_minmax (struct noce_if_info *if_info)
1517 rtx cond, earliest, target, seq;
1518 enum rtx_code code, op;
1521 /* ??? Can't guarantee that expand_binop won't create pseudos. */
1525 /* ??? Reject modes with NaNs or signed zeros since we don't know how
1526 they will be resolved with an SMIN/SMAX. It wouldn't be too hard
1527 to get the target to tell us... */
1528 if (HONOR_SIGNED_ZEROS (GET_MODE (if_info->x))
1529 || HONOR_NANS (GET_MODE (if_info->x)))
1532 cond = noce_get_alt_condition (if_info, if_info->a, &earliest);
1536 /* Verify the condition is of the form we expect, and canonicalize
1537 the comparison code. */
1538 code = GET_CODE (cond);
1539 if (rtx_equal_p (XEXP (cond, 0), if_info->a))
1541 if (! rtx_equal_p (XEXP (cond, 1), if_info->b))
1544 else if (rtx_equal_p (XEXP (cond, 1), if_info->a))
1546 if (! rtx_equal_p (XEXP (cond, 0), if_info->b))
1548 code = swap_condition (code);
1553 /* Determine what sort of operation this is. Note that the code is for
1554 a taken branch, so the code->operation mapping appears backwards. */
1587 target = expand_simple_binop (GET_MODE (if_info->x), op,
1588 if_info->a, if_info->b,
1589 if_info->x, unsignedp, OPTAB_WIDEN);
1595 if (target != if_info->x)
1596 noce_emit_move_insn (if_info->x, target);
1599 unshare_ifcvt_sequence (if_info, seq);
1602 if (seq_contains_jump (seq))
1605 emit_insn_before_setloc (seq, if_info->jump, INSN_LOCATOR (if_info->insn_a));
1606 if_info->cond = cond;
1607 if_info->cond_earliest = earliest;
1612 /* Convert "if (a < 0) x = -a; else x = a;" to "x = abs(a);", etc. */
1615 noce_try_abs (struct noce_if_info *if_info)
1617 rtx cond, earliest, target, seq, a, b, c;
1620 /* ??? Can't guarantee that expand_binop won't create pseudos. */
1624 /* Recognize A and B as constituting an ABS or NABS. */
1627 if (GET_CODE (a) == NEG && rtx_equal_p (XEXP (a, 0), b))
1629 else if (GET_CODE (b) == NEG && rtx_equal_p (XEXP (b, 0), a))
1631 c = a; a = b; b = c;
1637 cond = noce_get_alt_condition (if_info, b, &earliest);
1641 /* Verify the condition is of the form we expect. */
1642 if (rtx_equal_p (XEXP (cond, 0), b))
1644 else if (rtx_equal_p (XEXP (cond, 1), b))
1649 /* Verify that C is zero. Search backward through the block for
1650 a REG_EQUAL note if necessary. */
1653 rtx insn, note = NULL;
1654 for (insn = earliest;
1655 insn != BB_HEAD (if_info->test_bb);
1656 insn = PREV_INSN (insn))
1658 && ((note = find_reg_note (insn, REG_EQUAL, c))
1659 || (note = find_reg_note (insn, REG_EQUIV, c))))
1665 if (GET_CODE (c) == MEM
1666 && GET_CODE (XEXP (c, 0)) == SYMBOL_REF
1667 && CONSTANT_POOL_ADDRESS_P (XEXP (c, 0)))
1668 c = get_pool_constant (XEXP (c, 0));
1670 /* Work around funny ideas get_condition has wrt canonicalization.
1671 Note that these rtx constants are known to be CONST_INT, and
1672 therefore imply integer comparisons. */
1673 if (c == constm1_rtx && GET_CODE (cond) == GT)
1675 else if (c == const1_rtx && GET_CODE (cond) == LT)
1677 else if (c != CONST0_RTX (GET_MODE (b)))
1680 /* Determine what sort of operation this is. */
1681 switch (GET_CODE (cond))
1700 target = expand_abs_nojump (GET_MODE (if_info->x), b, if_info->x, 1);
1702 /* ??? It's a quandary whether cmove would be better here, especially
1703 for integers. Perhaps combine will clean things up. */
1704 if (target && negate)
1705 target = expand_simple_unop (GET_MODE (target), NEG, target, if_info->x, 0);
1713 if (target != if_info->x)
1714 noce_emit_move_insn (if_info->x, target);
1717 unshare_ifcvt_sequence (if_info, seq);
1720 if (seq_contains_jump (seq))
1723 emit_insn_before_setloc (seq, if_info->jump, INSN_LOCATOR (if_info->insn_a));
1724 if_info->cond = cond;
1725 if_info->cond_earliest = earliest;
1730 /* Similar to get_condition, only the resulting condition must be
1731 valid at JUMP, instead of at EARLIEST. */
1734 noce_get_condition (rtx jump, rtx *earliest)
1736 rtx cond, set, tmp, insn;
1739 if (! any_condjump_p (jump))
1742 set = pc_set (jump);
1744 /* If this branches to JUMP_LABEL when the condition is false,
1745 reverse the condition. */
1746 reverse = (GET_CODE (XEXP (SET_SRC (set), 2)) == LABEL_REF
1747 && XEXP (XEXP (SET_SRC (set), 2), 0) == JUMP_LABEL (jump));
1749 /* If the condition variable is a register and is MODE_INT, accept it. */
1751 cond = XEXP (SET_SRC (set), 0);
1752 tmp = XEXP (cond, 0);
1753 if (REG_P (tmp) && GET_MODE_CLASS (GET_MODE (tmp)) == MODE_INT)
1758 cond = gen_rtx_fmt_ee (reverse_condition (GET_CODE (cond)),
1759 GET_MODE (cond), tmp, XEXP (cond, 1));
1763 /* Otherwise, fall back on canonicalize_condition to do the dirty
1764 work of manipulating MODE_CC values and COMPARE rtx codes. */
1766 tmp = canonicalize_condition (jump, cond, reverse, earliest, NULL_RTX,
1771 /* We are going to insert code before JUMP, not before EARLIEST.
1772 We must therefore be certain that the given condition is valid
1773 at JUMP by virtue of not having been modified since. */
1774 for (insn = *earliest; insn != jump; insn = NEXT_INSN (insn))
1775 if (INSN_P (insn) && modified_in_p (tmp, insn))
1780 /* The condition was modified. See if we can get a partial result
1781 that doesn't follow all the reversals. Perhaps combine can fold
1782 them together later. */
1783 tmp = XEXP (tmp, 0);
1784 if (!REG_P (tmp) || GET_MODE_CLASS (GET_MODE (tmp)) != MODE_INT)
1786 tmp = canonicalize_condition (jump, cond, reverse, earliest, tmp,
1791 /* For sanity's sake, re-validate the new result. */
1792 for (insn = *earliest; insn != jump; insn = NEXT_INSN (insn))
1793 if (INSN_P (insn) && modified_in_p (tmp, insn))
1799 /* Return true if OP is ok for if-then-else processing. */
1802 noce_operand_ok (rtx op)
1804 /* We special-case memories, so handle any of them with
1805 no address side effects. */
1806 if (GET_CODE (op) == MEM)
1807 return ! side_effects_p (XEXP (op, 0));
1809 if (side_effects_p (op))
1812 return ! may_trap_p (op);
1815 /* Given a simple IF-THEN or IF-THEN-ELSE block, attempt to convert it
1816 without using conditional execution. Return TRUE if we were
1817 successful at converting the block. */
1820 noce_process_if_block (struct ce_if_block * ce_info)
1822 basic_block test_bb = ce_info->test_bb; /* test block */
1823 basic_block then_bb = ce_info->then_bb; /* THEN */
1824 basic_block else_bb = ce_info->else_bb; /* ELSE or NULL */
1825 struct noce_if_info if_info;
1828 rtx orig_x, x, a, b;
1831 /* We're looking for patterns of the form
1833 (1) if (...) x = a; else x = b;
1834 (2) x = b; if (...) x = a;
1835 (3) if (...) x = a; // as if with an initial x = x.
1837 The later patterns require jumps to be more expensive.
1839 ??? For future expansion, look for multiple X in such patterns. */
1841 /* If test is comprised of && or || elements, don't handle it unless it is
1842 the special case of && elements without an ELSE block. */
1843 if (ce_info->num_multiple_test_blocks)
1845 if (else_bb || ! ce_info->and_and_p)
1848 ce_info->test_bb = test_bb = ce_info->last_test_bb;
1849 ce_info->num_multiple_test_blocks = 0;
1850 ce_info->num_and_and_blocks = 0;
1851 ce_info->num_or_or_blocks = 0;
1854 /* If this is not a standard conditional jump, we can't parse it. */
1855 jump = BB_END (test_bb);
1856 cond = noce_get_condition (jump, &if_info.cond_earliest);
1860 /* If the conditional jump is more than just a conditional
1861 jump, then we can not do if-conversion on this block. */
1862 if (! onlyjump_p (jump))
1865 /* We must be comparing objects whose modes imply the size. */
1866 if (GET_MODE (XEXP (cond, 0)) == BLKmode)
1869 /* Look for one of the potential sets. */
1870 insn_a = first_active_insn (then_bb);
1872 || insn_a != last_active_insn (then_bb, FALSE)
1873 || (set_a = single_set (insn_a)) == NULL_RTX)
1876 x = SET_DEST (set_a);
1877 a = SET_SRC (set_a);
1879 /* Look for the other potential set. Make sure we've got equivalent
1881 /* ??? This is overconservative. Storing to two different mems is
1882 as easy as conditionally computing the address. Storing to a
1883 single mem merely requires a scratch memory to use as one of the
1884 destination addresses; often the memory immediately below the
1885 stack pointer is available for this. */
1889 insn_b = first_active_insn (else_bb);
1891 || insn_b != last_active_insn (else_bb, FALSE)
1892 || (set_b = single_set (insn_b)) == NULL_RTX
1893 || ! rtx_equal_p (x, SET_DEST (set_b)))
1898 insn_b = prev_nonnote_insn (if_info.cond_earliest);
1899 /* We're going to be moving the evaluation of B down from above
1900 COND_EARLIEST to JUMP. Make sure the relevant data is still
1903 || GET_CODE (insn_b) != INSN
1904 || (set_b = single_set (insn_b)) == NULL_RTX
1905 || ! rtx_equal_p (x, SET_DEST (set_b))
1906 || reg_overlap_mentioned_p (x, SET_SRC (set_b))
1907 || modified_between_p (SET_SRC (set_b),
1908 PREV_INSN (if_info.cond_earliest), jump)
1909 /* Likewise with X. In particular this can happen when
1910 noce_get_condition looks farther back in the instruction
1911 stream than one might expect. */
1912 || reg_overlap_mentioned_p (x, cond)
1913 || reg_overlap_mentioned_p (x, a)
1914 || modified_between_p (x, PREV_INSN (if_info.cond_earliest), jump))
1915 insn_b = set_b = NULL_RTX;
1918 /* If x has side effects then only the if-then-else form is safe to
1919 convert. But even in that case we would need to restore any notes
1920 (such as REG_INC) at then end. That can be tricky if
1921 noce_emit_move_insn expands to more than one insn, so disable the
1922 optimization entirely for now if there are side effects. */
1923 if (side_effects_p (x))
1926 b = (set_b ? SET_SRC (set_b) : x);
1928 /* Only operate on register destinations, and even then avoid extending
1929 the lifetime of hard registers on small register class machines. */
1931 if (GET_CODE (x) != REG
1932 || (SMALL_REGISTER_CLASSES
1933 && REGNO (x) < FIRST_PSEUDO_REGISTER))
1935 if (no_new_pseudos || GET_MODE (x) == BLKmode)
1937 x = gen_reg_rtx (GET_MODE (GET_CODE (x) == STRICT_LOW_PART
1938 ? XEXP (x, 0) : x));
1941 /* Don't operate on sources that may trap or are volatile. */
1942 if (! noce_operand_ok (a) || ! noce_operand_ok (b))
1945 /* Set up the info block for our subroutines. */
1946 if_info.test_bb = test_bb;
1947 if_info.cond = cond;
1948 if_info.jump = jump;
1949 if_info.insn_a = insn_a;
1950 if_info.insn_b = insn_b;
1955 /* Try optimizations in some approximation of a useful order. */
1956 /* ??? Should first look to see if X is live incoming at all. If it
1957 isn't, we don't need anything but an unconditional set. */
1959 /* Look and see if A and B are really the same. Avoid creating silly
1960 cmove constructs that no one will fix up later. */
1961 if (rtx_equal_p (a, b))
1963 /* If we have an INSN_B, we don't have to create any new rtl. Just
1964 move the instruction that we already have. If we don't have an
1965 INSN_B, that means that A == X, and we've got a noop move. In
1966 that case don't do anything and let the code below delete INSN_A. */
1967 if (insn_b && else_bb)
1971 if (else_bb && insn_b == BB_END (else_bb))
1972 BB_END (else_bb) = PREV_INSN (insn_b);
1973 reorder_insns (insn_b, insn_b, PREV_INSN (jump));
1975 /* If there was a REG_EQUAL note, delete it since it may have been
1976 true due to this insn being after a jump. */
1977 if ((note = find_reg_note (insn_b, REG_EQUAL, NULL_RTX)) != 0)
1978 remove_note (insn_b, note);
1982 /* If we have "x = b; if (...) x = a;", and x has side-effects, then
1983 x must be executed twice. */
1984 else if (insn_b && side_effects_p (orig_x))
1991 /* Disallow the "if (...) x = a;" form (with an implicit "else x = x;")
1992 for most optimizations if writing to x may trap, i.e. its a memory
1993 other than a static var or a stack slot. */
1995 && GET_CODE (orig_x) == MEM
1996 && ! MEM_NOTRAP_P (orig_x)
1997 && rtx_addr_can_trap_p (XEXP (orig_x, 0)))
1999 if (HAVE_conditional_move)
2001 if (noce_try_cmove (&if_info))
2003 if (! HAVE_conditional_execution
2004 && noce_try_cmove_arith (&if_info))
2010 if (noce_try_move (&if_info))
2012 if (noce_try_store_flag (&if_info))
2014 if (noce_try_minmax (&if_info))
2016 if (noce_try_abs (&if_info))
2018 if (HAVE_conditional_move
2019 && noce_try_cmove (&if_info))
2021 if (! HAVE_conditional_execution)
2023 if (noce_try_store_flag_constants (&if_info))
2025 if (noce_try_addcc (&if_info))
2027 if (noce_try_store_flag_mask (&if_info))
2029 if (HAVE_conditional_move
2030 && noce_try_cmove_arith (&if_info))
2037 /* The original sets may now be killed. */
2038 delete_insn (insn_a);
2040 /* Several special cases here: First, we may have reused insn_b above,
2041 in which case insn_b is now NULL. Second, we want to delete insn_b
2042 if it came from the ELSE block, because follows the now correct
2043 write that appears in the TEST block. However, if we got insn_b from
2044 the TEST block, it may in fact be loading data needed for the comparison.
2045 We'll let life_analysis remove the insn if it's really dead. */
2046 if (insn_b && else_bb)
2047 delete_insn (insn_b);
2049 /* The new insns will have been inserted immediately before the jump. We
2050 should be able to remove the jump with impunity, but the condition itself
2051 may have been modified by gcse to be shared across basic blocks. */
2054 /* If we used a temporary, fix it up now. */
2058 noce_emit_move_insn (orig_x, x);
2059 insn_b = get_insns ();
2060 set_used_flags (orig_x);
2061 unshare_all_rtl_in_chain (insn_b);
2064 emit_insn_after_setloc (insn_b, BB_END (test_bb), INSN_LOCATOR (insn_a));
2067 /* Merge the blocks! */
2068 merge_if_block (ce_info);
2073 /* Attempt to convert an IF-THEN or IF-THEN-ELSE block into
2074 straight line code. Return true if successful. */
2077 process_if_block (struct ce_if_block * ce_info)
2079 if (! reload_completed
2080 && noce_process_if_block (ce_info))
2083 if (HAVE_conditional_execution && reload_completed)
2085 /* If we have && and || tests, try to first handle combining the && and
2086 || tests into the conditional code, and if that fails, go back and
2087 handle it without the && and ||, which at present handles the && case
2088 if there was no ELSE block. */
2089 if (cond_exec_process_if_block (ce_info, TRUE))
2092 if (ce_info->num_multiple_test_blocks)
2096 if (cond_exec_process_if_block (ce_info, FALSE))
2104 /* Merge the blocks and mark for local life update. */
2107 merge_if_block (struct ce_if_block * ce_info)
2109 basic_block test_bb = ce_info->test_bb; /* last test block */
2110 basic_block then_bb = ce_info->then_bb; /* THEN */
2111 basic_block else_bb = ce_info->else_bb; /* ELSE or NULL */
2112 basic_block join_bb = ce_info->join_bb; /* join block */
2113 basic_block combo_bb;
2115 /* All block merging is done into the lower block numbers. */
2119 /* Merge any basic blocks to handle && and || subtests. Each of
2120 the blocks are on the fallthru path from the predecessor block. */
2121 if (ce_info->num_multiple_test_blocks > 0)
2123 basic_block bb = test_bb;
2124 basic_block last_test_bb = ce_info->last_test_bb;
2125 basic_block fallthru = block_fallthru (bb);
2130 fallthru = block_fallthru (bb);
2131 if (dom_computed[CDI_POST_DOMINATORS] >= DOM_NO_FAST_QUERY)
2132 delete_from_dominance_info (CDI_POST_DOMINATORS, bb);
2133 merge_blocks (combo_bb, bb);
2136 while (bb != last_test_bb);
2139 /* Merge TEST block into THEN block. Normally the THEN block won't have a
2140 label, but it might if there were || tests. That label's count should be
2141 zero, and it normally should be removed. */
2145 if (combo_bb->global_live_at_end)
2146 COPY_REG_SET (combo_bb->global_live_at_end,
2147 then_bb->global_live_at_end);
2148 if (dom_computed[CDI_POST_DOMINATORS] >= DOM_NO_FAST_QUERY)
2149 delete_from_dominance_info (CDI_POST_DOMINATORS, then_bb);
2150 merge_blocks (combo_bb, then_bb);
2154 /* The ELSE block, if it existed, had a label. That label count
2155 will almost always be zero, but odd things can happen when labels
2156 get their addresses taken. */
2159 if (dom_computed[CDI_POST_DOMINATORS] >= DOM_NO_FAST_QUERY)
2160 delete_from_dominance_info (CDI_POST_DOMINATORS, else_bb);
2161 merge_blocks (combo_bb, else_bb);
2165 /* If there was no join block reported, that means it was not adjacent
2166 to the others, and so we cannot merge them. */
2170 rtx last = BB_END (combo_bb);
2172 /* The outgoing edge for the current COMBO block should already
2173 be correct. Verify this. */
2174 if (combo_bb->succ == NULL_EDGE)
2176 if (find_reg_note (last, REG_NORETURN, NULL))
2178 else if (GET_CODE (last) == INSN
2179 && GET_CODE (PATTERN (last)) == TRAP_IF
2180 && TRAP_CONDITION (PATTERN (last)) == const_true_rtx)
2186 /* There should still be something at the end of the THEN or ELSE
2187 blocks taking us to our final destination. */
2188 else if (GET_CODE (last) == JUMP_INSN)
2190 else if (combo_bb->succ->dest == EXIT_BLOCK_PTR
2191 && GET_CODE (last) == CALL_INSN
2192 && SIBLING_CALL_P (last))
2194 else if ((combo_bb->succ->flags & EDGE_EH)
2195 && can_throw_internal (last))
2201 /* The JOIN block may have had quite a number of other predecessors too.
2202 Since we've already merged the TEST, THEN and ELSE blocks, we should
2203 have only one remaining edge from our if-then-else diamond. If there
2204 is more than one remaining edge, it must come from elsewhere. There
2205 may be zero incoming edges if the THEN block didn't actually join
2206 back up (as with a call to abort). */
2207 else if ((join_bb->pred == NULL
2208 || join_bb->pred->pred_next == NULL)
2209 && join_bb != EXIT_BLOCK_PTR)
2211 /* We can merge the JOIN. */
2212 if (combo_bb->global_live_at_end)
2213 COPY_REG_SET (combo_bb->global_live_at_end,
2214 join_bb->global_live_at_end);
2216 if (dom_computed[CDI_POST_DOMINATORS] >= DOM_NO_FAST_QUERY)
2217 delete_from_dominance_info (CDI_POST_DOMINATORS, join_bb);
2218 merge_blocks (combo_bb, join_bb);
2223 /* We cannot merge the JOIN. */
2225 /* The outgoing edge for the current COMBO block should already
2226 be correct. Verify this. */
2227 if (combo_bb->succ->succ_next != NULL_EDGE
2228 || combo_bb->succ->dest != join_bb)
2231 /* Remove the jump and cruft from the end of the COMBO block. */
2232 if (join_bb != EXIT_BLOCK_PTR)
2233 tidy_fallthru_edge (combo_bb->succ, combo_bb, join_bb);
2236 num_updated_if_blocks++;
2239 /* Find a block ending in a simple IF condition and try to transform it
2240 in some way. When converting a multi-block condition, put the new code
2241 in the first such block and delete the rest. Return a pointer to this
2242 first block if some transformation was done. Return NULL otherwise. */
2245 find_if_header (basic_block test_bb, int pass)
2247 ce_if_block_t ce_info;
2251 /* The kind of block we're looking for has exactly two successors. */
2252 if ((then_edge = test_bb->succ) == NULL_EDGE
2253 || (else_edge = then_edge->succ_next) == NULL_EDGE
2254 || else_edge->succ_next != NULL_EDGE)
2257 /* Neither edge should be abnormal. */
2258 if ((then_edge->flags & EDGE_COMPLEX)
2259 || (else_edge->flags & EDGE_COMPLEX))
2262 /* Nor exit the loop. */
2263 if ((then_edge->flags & EDGE_LOOP_EXIT)
2264 || (else_edge->flags & EDGE_LOOP_EXIT))
2267 /* The THEN edge is canonically the one that falls through. */
2268 if (then_edge->flags & EDGE_FALLTHRU)
2270 else if (else_edge->flags & EDGE_FALLTHRU)
2273 else_edge = then_edge;
2277 /* Otherwise this must be a multiway branch of some sort. */
2280 memset (&ce_info, '\0', sizeof (ce_info));
2281 ce_info.test_bb = test_bb;
2282 ce_info.then_bb = then_edge->dest;
2283 ce_info.else_bb = else_edge->dest;
2284 ce_info.pass = pass;
2286 #ifdef IFCVT_INIT_EXTRA_FIELDS
2287 IFCVT_INIT_EXTRA_FIELDS (&ce_info);
2290 if (find_if_block (&ce_info))
2293 if (HAVE_trap && HAVE_conditional_trap
2294 && find_cond_trap (test_bb, then_edge, else_edge))
2297 if (dom_computed[CDI_POST_DOMINATORS] >= DOM_NO_FAST_QUERY
2298 && (! HAVE_conditional_execution || reload_completed))
2300 if (find_if_case_1 (test_bb, then_edge, else_edge))
2302 if (find_if_case_2 (test_bb, then_edge, else_edge))
2310 fprintf (rtl_dump_file, "Conversion succeeded on pass %d.\n", pass);
2311 return ce_info.test_bb;
2314 /* Return true if a block has two edges, one of which falls through to the next
2315 block, and the other jumps to a specific block, so that we can tell if the
2316 block is part of an && test or an || test. Returns either -1 or the number
2317 of non-note, non-jump, non-USE/CLOBBER insns in the block. */
2320 block_jumps_and_fallthru_p (basic_block cur_bb, basic_block target_bb)
2323 int fallthru_p = FALSE;
2329 if (!cur_bb || !target_bb)
2332 /* If no edges, obviously it doesn't jump or fallthru. */
2333 if (cur_bb->succ == NULL_EDGE)
2336 for (cur_edge = cur_bb->succ;
2337 cur_edge != NULL_EDGE;
2338 cur_edge = cur_edge->succ_next)
2340 if (cur_edge->flags & EDGE_COMPLEX)
2341 /* Anything complex isn't what we want. */
2344 else if (cur_edge->flags & EDGE_FALLTHRU)
2347 else if (cur_edge->dest == target_bb)
2354 if ((jump_p & fallthru_p) == 0)
2357 /* Don't allow calls in the block, since this is used to group && and ||
2358 together for conditional execution support. ??? we should support
2359 conditional execution support across calls for IA-64 some day, but
2360 for now it makes the code simpler. */
2361 end = BB_END (cur_bb);
2362 insn = BB_HEAD (cur_bb);
2364 while (insn != NULL_RTX)
2366 if (GET_CODE (insn) == CALL_INSN)
2370 && GET_CODE (insn) != JUMP_INSN
2371 && GET_CODE (PATTERN (insn)) != USE
2372 && GET_CODE (PATTERN (insn)) != CLOBBER)
2378 insn = NEXT_INSN (insn);
2384 /* Determine if a given basic block heads a simple IF-THEN or IF-THEN-ELSE
2385 block. If so, we'll try to convert the insns to not require the branch.
2386 Return TRUE if we were successful at converting the block. */
2389 find_if_block (struct ce_if_block * ce_info)
2391 basic_block test_bb = ce_info->test_bb;
2392 basic_block then_bb = ce_info->then_bb;
2393 basic_block else_bb = ce_info->else_bb;
2394 basic_block join_bb = NULL_BLOCK;
2395 edge then_succ = then_bb->succ;
2396 edge else_succ = else_bb->succ;
2397 int then_predecessors;
2398 int else_predecessors;
2402 ce_info->last_test_bb = test_bb;
2404 /* Discover if any fall through predecessors of the current test basic block
2405 were && tests (which jump to the else block) or || tests (which jump to
2407 if (HAVE_conditional_execution && reload_completed
2408 && test_bb->pred != NULL_EDGE
2409 && test_bb->pred->pred_next == NULL_EDGE
2410 && test_bb->pred->flags == EDGE_FALLTHRU)
2412 basic_block bb = test_bb->pred->src;
2413 basic_block target_bb;
2414 int max_insns = MAX_CONDITIONAL_EXECUTE;
2417 /* Determine if the preceding block is an && or || block. */
2418 if ((n_insns = block_jumps_and_fallthru_p (bb, else_bb)) >= 0)
2420 ce_info->and_and_p = TRUE;
2421 target_bb = else_bb;
2423 else if ((n_insns = block_jumps_and_fallthru_p (bb, then_bb)) >= 0)
2425 ce_info->and_and_p = FALSE;
2426 target_bb = then_bb;
2429 target_bb = NULL_BLOCK;
2431 if (target_bb && n_insns <= max_insns)
2433 int total_insns = 0;
2436 ce_info->last_test_bb = test_bb;
2438 /* Found at least one && or || block, look for more. */
2441 ce_info->test_bb = test_bb = bb;
2442 total_insns += n_insns;
2445 if (bb->pred == NULL_EDGE || bb->pred->pred_next != NULL_EDGE)
2449 n_insns = block_jumps_and_fallthru_p (bb, target_bb);
2451 while (n_insns >= 0 && (total_insns + n_insns) <= max_insns);
2453 ce_info->num_multiple_test_blocks = blocks;
2454 ce_info->num_multiple_test_insns = total_insns;
2456 if (ce_info->and_and_p)
2457 ce_info->num_and_and_blocks = blocks;
2459 ce_info->num_or_or_blocks = blocks;
2463 /* Count the number of edges the THEN and ELSE blocks have. */
2464 then_predecessors = 0;
2465 for (cur_edge = then_bb->pred;
2466 cur_edge != NULL_EDGE;
2467 cur_edge = cur_edge->pred_next)
2469 then_predecessors++;
2470 if (cur_edge->flags & EDGE_COMPLEX)
2474 else_predecessors = 0;
2475 for (cur_edge = else_bb->pred;
2476 cur_edge != NULL_EDGE;
2477 cur_edge = cur_edge->pred_next)
2479 else_predecessors++;
2480 if (cur_edge->flags & EDGE_COMPLEX)
2484 /* The THEN block of an IF-THEN combo must have exactly one predecessor,
2485 other than any || blocks which jump to the THEN block. */
2486 if ((then_predecessors - ce_info->num_or_or_blocks) != 1)
2489 /* The THEN block of an IF-THEN combo must have zero or one successors. */
2490 if (then_succ != NULL_EDGE
2491 && (then_succ->succ_next != NULL_EDGE
2492 || (then_succ->flags & EDGE_COMPLEX)
2493 || (flow2_completed && tablejump_p (BB_END (then_bb), NULL, NULL))))
2496 /* If the THEN block has no successors, conditional execution can still
2497 make a conditional call. Don't do this unless the ELSE block has
2498 only one incoming edge -- the CFG manipulation is too ugly otherwise.
2499 Check for the last insn of the THEN block being an indirect jump, which
2500 is listed as not having any successors, but confuses the rest of the CE
2501 code processing. ??? we should fix this in the future. */
2502 if (then_succ == NULL)
2504 if (else_bb->pred->pred_next == NULL_EDGE)
2506 rtx last_insn = BB_END (then_bb);
2509 && GET_CODE (last_insn) == NOTE
2510 && last_insn != BB_HEAD (then_bb))
2511 last_insn = PREV_INSN (last_insn);
2514 && GET_CODE (last_insn) == JUMP_INSN
2515 && ! simplejump_p (last_insn))
2519 else_bb = NULL_BLOCK;
2525 /* If the THEN block's successor is the other edge out of the TEST block,
2526 then we have an IF-THEN combo without an ELSE. */
2527 else if (then_succ->dest == else_bb)
2530 else_bb = NULL_BLOCK;
2533 /* If the THEN and ELSE block meet in a subsequent block, and the ELSE
2534 has exactly one predecessor and one successor, and the outgoing edge
2535 is not complex, then we have an IF-THEN-ELSE combo. */
2536 else if (else_succ != NULL_EDGE
2537 && then_succ->dest == else_succ->dest
2538 && else_bb->pred->pred_next == NULL_EDGE
2539 && else_succ->succ_next == NULL_EDGE
2540 && ! (else_succ->flags & EDGE_COMPLEX)
2541 && ! (flow2_completed && tablejump_p (BB_END (else_bb), NULL, NULL)))
2542 join_bb = else_succ->dest;
2544 /* Otherwise it is not an IF-THEN or IF-THEN-ELSE combination. */
2548 num_possible_if_blocks++;
2552 fprintf (rtl_dump_file, "\nIF-THEN%s block found, pass %d, start block %d [insn %d], then %d [%d]",
2553 (else_bb) ? "-ELSE" : "",
2555 test_bb->index, (BB_HEAD (test_bb)) ? (int)INSN_UID (BB_HEAD (test_bb)) : -1,
2556 then_bb->index, (BB_HEAD (then_bb)) ? (int)INSN_UID (BB_HEAD (then_bb)) : -1);
2559 fprintf (rtl_dump_file, ", else %d [%d]",
2560 else_bb->index, (BB_HEAD (else_bb)) ? (int)INSN_UID (BB_HEAD (else_bb)) : -1);
2562 fprintf (rtl_dump_file, ", join %d [%d]",
2563 join_bb->index, (BB_HEAD (join_bb)) ? (int)INSN_UID (BB_HEAD (join_bb)) : -1);
2565 if (ce_info->num_multiple_test_blocks > 0)
2566 fprintf (rtl_dump_file, ", %d %s block%s last test %d [%d]",
2567 ce_info->num_multiple_test_blocks,
2568 (ce_info->and_and_p) ? "&&" : "||",
2569 (ce_info->num_multiple_test_blocks == 1) ? "" : "s",
2570 ce_info->last_test_bb->index,
2571 ((BB_HEAD (ce_info->last_test_bb))
2572 ? (int)INSN_UID (BB_HEAD (ce_info->last_test_bb))
2575 fputc ('\n', rtl_dump_file);
2578 /* Make sure IF, THEN, and ELSE, blocks are adjacent. Actually, we get the
2579 first condition for free, since we've already asserted that there's a
2580 fallthru edge from IF to THEN. Likewise for the && and || blocks, since
2581 we checked the FALLTHRU flag, those are already adjacent to the last IF
2583 /* ??? As an enhancement, move the ELSE block. Have to deal with
2584 BLOCK notes, if by no other means than aborting the merge if they
2585 exist. Sticky enough I don't want to think about it now. */
2587 if (else_bb && (next = next->next_bb) != else_bb)
2589 if ((next = next->next_bb) != join_bb && join_bb != EXIT_BLOCK_PTR)
2597 /* Do the real work. */
2598 ce_info->else_bb = else_bb;
2599 ce_info->join_bb = join_bb;
2601 return process_if_block (ce_info);
2604 /* Convert a branch over a trap, or a branch
2605 to a trap, into a conditional trap. */
2608 find_cond_trap (basic_block test_bb, edge then_edge, edge else_edge)
2610 basic_block then_bb = then_edge->dest;
2611 basic_block else_bb = else_edge->dest;
2612 basic_block other_bb, trap_bb;
2613 rtx trap, jump, cond, cond_earliest, seq;
2616 /* Locate the block with the trap instruction. */
2617 /* ??? While we look for no successors, we really ought to allow
2618 EH successors. Need to fix merge_if_block for that to work. */
2619 if ((trap = block_has_only_trap (then_bb)) != NULL)
2620 trap_bb = then_bb, other_bb = else_bb;
2621 else if ((trap = block_has_only_trap (else_bb)) != NULL)
2622 trap_bb = else_bb, other_bb = then_bb;
2628 fprintf (rtl_dump_file, "\nTRAP-IF block found, start %d, trap %d\n",
2629 test_bb->index, trap_bb->index);
2632 /* If this is not a standard conditional jump, we can't parse it. */
2633 jump = BB_END (test_bb);
2634 cond = noce_get_condition (jump, &cond_earliest);
2638 /* If the conditional jump is more than just a conditional jump, then
2639 we can not do if-conversion on this block. */
2640 if (! onlyjump_p (jump))
2643 /* We must be comparing objects whose modes imply the size. */
2644 if (GET_MODE (XEXP (cond, 0)) == BLKmode)
2647 /* Reverse the comparison code, if necessary. */
2648 code = GET_CODE (cond);
2649 if (then_bb == trap_bb)
2651 code = reversed_comparison_code (cond, jump);
2652 if (code == UNKNOWN)
2656 /* Attempt to generate the conditional trap. */
2657 seq = gen_cond_trap (code, XEXP (cond, 0),
2659 TRAP_CODE (PATTERN (trap)));
2665 /* Emit the new insns before cond_earliest. */
2666 emit_insn_before_setloc (seq, cond_earliest, INSN_LOCATOR (trap));
2668 /* Delete the trap block if possible. */
2669 remove_edge (trap_bb == then_bb ? then_edge : else_edge);
2670 if (trap_bb->pred == NULL)
2672 if (dom_computed[CDI_POST_DOMINATORS] >= DOM_NO_FAST_QUERY)
2673 delete_from_dominance_info (CDI_POST_DOMINATORS, trap_bb);
2674 delete_block (trap_bb);
2677 /* If the non-trap block and the test are now adjacent, merge them.
2678 Otherwise we must insert a direct branch. */
2679 if (test_bb->next_bb == other_bb)
2681 struct ce_if_block new_ce_info;
2683 memset (&new_ce_info, '\0', sizeof (new_ce_info));
2684 new_ce_info.test_bb = test_bb;
2685 new_ce_info.then_bb = NULL;
2686 new_ce_info.else_bb = NULL;
2687 new_ce_info.join_bb = other_bb;
2688 merge_if_block (&new_ce_info);
2694 lab = JUMP_LABEL (jump);
2695 newjump = emit_jump_insn_after (gen_jump (lab), jump);
2696 LABEL_NUSES (lab) += 1;
2697 JUMP_LABEL (newjump) = lab;
2698 emit_barrier_after (newjump);
2706 /* Subroutine of find_cond_trap: if BB contains only a trap insn,
2710 block_has_only_trap (basic_block bb)
2714 /* We're not the exit block. */
2715 if (bb == EXIT_BLOCK_PTR)
2718 /* The block must have no successors. */
2722 /* The only instruction in the THEN block must be the trap. */
2723 trap = first_active_insn (bb);
2724 if (! (trap == BB_END (bb)
2725 && GET_CODE (PATTERN (trap)) == TRAP_IF
2726 && TRAP_CONDITION (PATTERN (trap)) == const_true_rtx))
2732 /* Look for IF-THEN-ELSE cases in which one of THEN or ELSE is
2733 transformable, but not necessarily the other. There need be no
2736 Return TRUE if we were successful at converting the block.
2738 Cases we'd like to look at:
2741 if (test) goto over; // x not live
2749 if (! test) goto label;
2752 if (test) goto E; // x not live
2766 (3) // This one's really only interesting for targets that can do
2767 // multiway branching, e.g. IA-64 BBB bundles. For other targets
2768 // it results in multiple branches on a cache line, which often
2769 // does not sit well with predictors.
2771 if (test1) goto E; // predicted not taken
2787 (A) Don't do (2) if the branch is predicted against the block we're
2788 eliminating. Do it anyway if we can eliminate a branch; this requires
2789 that the sole successor of the eliminated block postdominate the other
2792 (B) With CE, on (3) we can steal from both sides of the if, creating
2801 Again, this is most useful if J postdominates.
2803 (C) CE substitutes for helpful life information.
2805 (D) These heuristics need a lot of work. */
2807 /* Tests for case 1 above. */
2810 find_if_case_1 (basic_block test_bb, edge then_edge, edge else_edge)
2812 basic_block then_bb = then_edge->dest;
2813 basic_block else_bb = else_edge->dest, new_bb;
2814 edge then_succ = then_bb->succ;
2817 /* THEN has one successor. */
2818 if (!then_succ || then_succ->succ_next != NULL)
2821 /* THEN does not fall through, but is not strange either. */
2822 if (then_succ->flags & (EDGE_COMPLEX | EDGE_FALLTHRU))
2825 /* THEN has one predecessor. */
2826 if (then_bb->pred->pred_next != NULL)
2829 /* THEN must do something. */
2830 if (forwarder_block_p (then_bb))
2833 num_possible_if_blocks++;
2835 fprintf (rtl_dump_file,
2836 "\nIF-CASE-1 found, start %d, then %d\n",
2837 test_bb->index, then_bb->index);
2839 /* THEN is small. */
2840 if (count_bb_insns (then_bb) > BRANCH_COST)
2843 /* Registers set are dead, or are predicable. */
2844 if (! dead_or_predicable (test_bb, then_bb, else_bb,
2845 then_bb->succ->dest, 1))
2848 /* Conversion went ok, including moving the insns and fixing up the
2849 jump. Adjust the CFG to match. */
2851 bitmap_operation (test_bb->global_live_at_end,
2852 else_bb->global_live_at_start,
2853 then_bb->global_live_at_end, BITMAP_IOR);
2855 new_bb = redirect_edge_and_branch_force (FALLTHRU_EDGE (test_bb), else_bb);
2856 then_bb_index = then_bb->index;
2857 if (dom_computed[CDI_POST_DOMINATORS] >= DOM_NO_FAST_QUERY)
2858 delete_from_dominance_info (CDI_POST_DOMINATORS, then_bb);
2859 delete_block (then_bb);
2861 /* Make rest of code believe that the newly created block is the THEN_BB
2862 block we removed. */
2865 new_bb->index = then_bb_index;
2866 BASIC_BLOCK (then_bb_index) = new_bb;
2867 if (dom_computed[CDI_POST_DOMINATORS] >= DOM_NO_FAST_QUERY)
2868 add_to_dominance_info (CDI_POST_DOMINATORS, new_bb);
2870 /* We've possibly created jump to next insn, cleanup_cfg will solve that
2874 num_updated_if_blocks++;
2879 /* Test for case 2 above. */
2882 find_if_case_2 (basic_block test_bb, edge then_edge, edge else_edge)
2884 basic_block then_bb = then_edge->dest;
2885 basic_block else_bb = else_edge->dest;
2886 edge else_succ = else_bb->succ;
2889 /* ELSE has one successor. */
2890 if (!else_succ || else_succ->succ_next != NULL)
2893 /* ELSE outgoing edge is not complex. */
2894 if (else_succ->flags & EDGE_COMPLEX)
2897 /* ELSE has one predecessor. */
2898 if (else_bb->pred->pred_next != NULL)
2901 /* THEN is not EXIT. */
2902 if (then_bb->index < 0)
2905 /* ELSE is predicted or SUCC(ELSE) postdominates THEN. */
2906 note = find_reg_note (BB_END (test_bb), REG_BR_PROB, NULL_RTX);
2907 if (note && INTVAL (XEXP (note, 0)) >= REG_BR_PROB_BASE / 2)
2909 else if (else_succ->dest->index < 0
2910 || dominated_by_p (CDI_POST_DOMINATORS, then_bb,
2916 num_possible_if_blocks++;
2918 fprintf (rtl_dump_file,
2919 "\nIF-CASE-2 found, start %d, else %d\n",
2920 test_bb->index, else_bb->index);
2922 /* ELSE is small. */
2923 if (count_bb_insns (else_bb) > BRANCH_COST)
2926 /* Registers set are dead, or are predicable. */
2927 if (! dead_or_predicable (test_bb, else_bb, then_bb, else_succ->dest, 0))
2930 /* Conversion went ok, including moving the insns and fixing up the
2931 jump. Adjust the CFG to match. */
2933 bitmap_operation (test_bb->global_live_at_end,
2934 then_bb->global_live_at_start,
2935 else_bb->global_live_at_end, BITMAP_IOR);
2937 if (dom_computed[CDI_POST_DOMINATORS] >= DOM_NO_FAST_QUERY)
2938 delete_from_dominance_info (CDI_POST_DOMINATORS, else_bb);
2939 delete_block (else_bb);
2942 num_updated_if_blocks++;
2944 /* ??? We may now fallthru from one of THEN's successors into a join
2945 block. Rerun cleanup_cfg? Examine things manually? Wait? */
2950 /* A subroutine of dead_or_predicable called through for_each_rtx.
2951 Return 1 if a memory is found. */
2954 find_memory (rtx *px, void *data ATTRIBUTE_UNUSED)
2956 return GET_CODE (*px) == MEM;
2959 /* Used by the code above to perform the actual rtl transformations.
2960 Return TRUE if successful.
2962 TEST_BB is the block containing the conditional branch. MERGE_BB
2963 is the block containing the code to manipulate. NEW_DEST is the
2964 label TEST_BB should be branching to after the conversion.
2965 REVERSEP is true if the sense of the branch should be reversed. */
2968 dead_or_predicable (basic_block test_bb, basic_block merge_bb,
2969 basic_block other_bb, basic_block new_dest, int reversep)
2971 rtx head, end, jump, earliest, old_dest, new_label = NULL_RTX;
2973 jump = BB_END (test_bb);
2975 /* Find the extent of the real code in the merge block. */
2976 head = BB_HEAD (merge_bb);
2977 end = BB_END (merge_bb);
2979 if (GET_CODE (head) == CODE_LABEL)
2980 head = NEXT_INSN (head);
2981 if (GET_CODE (head) == NOTE)
2985 head = end = NULL_RTX;
2988 head = NEXT_INSN (head);
2991 if (GET_CODE (end) == JUMP_INSN)
2995 head = end = NULL_RTX;
2998 end = PREV_INSN (end);
3001 /* Disable handling dead code by conditional execution if the machine needs
3002 to do anything funny with the tests, etc. */
3003 #ifndef IFCVT_MODIFY_TESTS
3004 if (HAVE_conditional_execution)
3006 /* In the conditional execution case, we have things easy. We know
3007 the condition is reversible. We don't have to check life info
3008 because we're going to conditionally execute the code anyway.
3009 All that's left is making sure the insns involved can actually
3014 cond = cond_exec_get_condition (jump);
3018 prob_val = find_reg_note (jump, REG_BR_PROB, NULL_RTX);
3020 prob_val = XEXP (prob_val, 0);
3024 enum rtx_code rev = reversed_comparison_code (cond, jump);
3027 cond = gen_rtx_fmt_ee (rev, GET_MODE (cond), XEXP (cond, 0),
3030 prob_val = GEN_INT (REG_BR_PROB_BASE - INTVAL (prob_val));
3033 if (! cond_exec_process_insns ((ce_if_block_t *)0, head, end, cond,
3042 /* In the non-conditional execution case, we have to verify that there
3043 are no trapping operations, no calls, no references to memory, and
3044 that any registers modified are dead at the branch site. */
3046 rtx insn, cond, prev;
3047 regset_head merge_set_head, tmp_head, test_live_head, test_set_head;
3048 regset merge_set, tmp, test_live, test_set;
3049 struct propagate_block_info *pbi;
3052 /* Check for no calls or trapping operations. */
3053 for (insn = head; ; insn = NEXT_INSN (insn))
3055 if (GET_CODE (insn) == CALL_INSN)
3059 if (may_trap_p (PATTERN (insn)))
3062 /* ??? Even non-trapping memories such as stack frame
3063 references must be avoided. For stores, we collect
3064 no lifetime info; for reads, we'd have to assert
3065 true_dependence false against every store in the
3067 if (for_each_rtx (&PATTERN (insn), find_memory, NULL))
3074 if (! any_condjump_p (jump))
3077 /* Find the extent of the conditional. */
3078 cond = noce_get_condition (jump, &earliest);
3083 MERGE_SET = set of registers set in MERGE_BB
3084 TEST_LIVE = set of registers live at EARLIEST
3085 TEST_SET = set of registers set between EARLIEST and the
3086 end of the block. */
3088 tmp = INITIALIZE_REG_SET (tmp_head);
3089 merge_set = INITIALIZE_REG_SET (merge_set_head);
3090 test_live = INITIALIZE_REG_SET (test_live_head);
3091 test_set = INITIALIZE_REG_SET (test_set_head);
3093 /* ??? bb->local_set is only valid during calculate_global_regs_live,
3094 so we must recompute usage for MERGE_BB. Not so bad, I suppose,
3095 since we've already asserted that MERGE_BB is small. */
3096 propagate_block (merge_bb, tmp, merge_set, merge_set, 0);
3098 /* For small register class machines, don't lengthen lifetimes of
3099 hard registers before reload. */
3100 if (SMALL_REGISTER_CLASSES && ! reload_completed)
3102 EXECUTE_IF_SET_IN_BITMAP
3105 if (i < FIRST_PSEUDO_REGISTER
3107 && ! global_regs[i])
3112 /* For TEST, we're interested in a range of insns, not a whole block.
3113 Moreover, we're interested in the insns live from OTHER_BB. */
3115 COPY_REG_SET (test_live, other_bb->global_live_at_start);
3116 pbi = init_propagate_block_info (test_bb, test_live, test_set, test_set,
3119 for (insn = jump; ; insn = prev)
3121 prev = propagate_one_insn (pbi, insn);
3122 if (insn == earliest)
3126 free_propagate_block_info (pbi);
3128 /* We can perform the transformation if
3129 MERGE_SET & (TEST_SET | TEST_LIVE)
3131 TEST_SET & merge_bb->global_live_at_start
3134 bitmap_operation (tmp, test_set, test_live, BITMAP_IOR);
3135 bitmap_operation (tmp, tmp, merge_set, BITMAP_AND);
3136 EXECUTE_IF_SET_IN_BITMAP(tmp, 0, i, fail = 1);
3138 bitmap_operation (tmp, test_set, merge_bb->global_live_at_start,
3140 EXECUTE_IF_SET_IN_BITMAP(tmp, 0, i, fail = 1);
3143 FREE_REG_SET (merge_set);
3144 FREE_REG_SET (test_live);
3145 FREE_REG_SET (test_set);
3152 /* We don't want to use normal invert_jump or redirect_jump because
3153 we don't want to delete_insn called. Also, we want to do our own
3154 change group management. */
3156 old_dest = JUMP_LABEL (jump);
3157 if (other_bb != new_dest)
3159 new_label = block_label (new_dest);
3161 ? ! invert_jump_1 (jump, new_label)
3162 : ! redirect_jump_1 (jump, new_label))
3166 if (! apply_change_group ())
3169 if (other_bb != new_dest)
3172 LABEL_NUSES (old_dest) -= 1;
3174 LABEL_NUSES (new_label) += 1;
3175 JUMP_LABEL (jump) = new_label;
3177 invert_br_probabilities (jump);
3179 redirect_edge_succ (BRANCH_EDGE (test_bb), new_dest);
3182 gcov_type count, probability;
3183 count = BRANCH_EDGE (test_bb)->count;
3184 BRANCH_EDGE (test_bb)->count = FALLTHRU_EDGE (test_bb)->count;
3185 FALLTHRU_EDGE (test_bb)->count = count;
3186 probability = BRANCH_EDGE (test_bb)->probability;
3187 BRANCH_EDGE (test_bb)->probability
3188 = FALLTHRU_EDGE (test_bb)->probability;
3189 FALLTHRU_EDGE (test_bb)->probability = probability;
3190 update_br_prob_note (test_bb);
3194 /* Move the insns out of MERGE_BB to before the branch. */
3197 if (end == BB_END (merge_bb))
3198 BB_END (merge_bb) = PREV_INSN (head);
3200 if (squeeze_notes (&head, &end))
3203 reorder_insns (head, end, PREV_INSN (earliest));
3206 /* Remove the jump and edge if we can. */
3207 if (other_bb == new_dest)
3210 remove_edge (BRANCH_EDGE (test_bb));
3211 /* ??? Can't merge blocks here, as then_bb is still in use.
3212 At minimum, the merge will get done just before bb-reorder. */
3222 /* Main entry point for all if-conversion. */
3225 if_convert (int x_life_data_ok)
3230 num_possible_if_blocks = 0;
3231 num_updated_if_blocks = 0;
3232 num_true_changes = 0;
3233 life_data_ok = (x_life_data_ok != 0);
3235 if (! (* targetm.cannot_modify_jumps_p) ())
3236 mark_loop_exit_edges ();
3238 /* Free up basic_block_for_insn so that we don't have to keep it
3239 up to date, either here or in merge_blocks. */
3240 free_basic_block_vars (1);
3242 /* Compute postdominators if we think we'll use them. */
3243 if (HAVE_conditional_execution || life_data_ok)
3244 calculate_dominance_info (CDI_POST_DOMINATORS);
3249 /* Go through each of the basic blocks looking for things to convert. If we
3250 have conditional execution, we make multiple passes to allow us to handle
3251 IF-THEN{-ELSE} blocks within other IF-THEN{-ELSE} blocks. */
3255 cond_exec_changed_p = FALSE;
3258 #ifdef IFCVT_MULTIPLE_DUMPS
3259 if (rtl_dump_file && pass > 1)
3260 fprintf (rtl_dump_file, "\n\n========== Pass %d ==========\n", pass);
3266 while ((new_bb = find_if_header (bb, pass)))
3270 #ifdef IFCVT_MULTIPLE_DUMPS
3271 if (rtl_dump_file && cond_exec_changed_p)
3272 print_rtl_with_bb (rtl_dump_file, get_insns ());
3275 while (cond_exec_changed_p);
3277 #ifdef IFCVT_MULTIPLE_DUMPS
3279 fprintf (rtl_dump_file, "\n\n========== no more changes\n");
3282 free_dominance_info (CDI_POST_DOMINATORS);
3285 fflush (rtl_dump_file);
3287 clear_aux_for_blocks ();
3289 /* Rebuild life info for basic blocks that require it. */
3290 if (num_true_changes && life_data_ok)
3292 /* If we allocated new pseudos, we must resize the array for sched1. */
3293 if (max_regno < max_reg_num ())
3295 max_regno = max_reg_num ();
3296 allocate_reg_info (max_regno, FALSE, FALSE);
3298 update_life_info_in_dirty_blocks (UPDATE_LIFE_GLOBAL_RM_NOTES,
3299 PROP_DEATH_NOTES | PROP_SCAN_DEAD_CODE
3300 | PROP_KILL_DEAD_CODE);
3303 /* Write the final stats. */
3304 if (rtl_dump_file && num_possible_if_blocks > 0)
3306 fprintf (rtl_dump_file,
3307 "\n%d possible IF blocks searched.\n",
3308 num_possible_if_blocks);
3309 fprintf (rtl_dump_file,
3310 "%d IF blocks converted.\n",
3311 num_updated_if_blocks);
3312 fprintf (rtl_dump_file,
3313 "%d true changes made.\n\n\n",
3317 #ifdef ENABLE_CHECKING
3318 verify_flow_info ();