1 /* If-conversion support.
2 Copyright (C) 2000, 2001, 2002, 2003, 2004 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 (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 *);
615 static int noce_try_sign_mask (struct noce_if_info *);
617 /* Helper function for noce_try_store_flag*. */
620 noce_emit_store_flag (struct noce_if_info *if_info, rtx x, int reversep,
623 rtx cond = if_info->cond;
627 cond_complex = (! general_operand (XEXP (cond, 0), VOIDmode)
628 || ! general_operand (XEXP (cond, 1), VOIDmode));
630 /* If earliest == jump, or when the condition is complex, try to
631 build the store_flag insn directly. */
634 cond = XEXP (SET_SRC (pc_set (if_info->jump)), 0);
637 code = reversed_comparison_code (cond, if_info->jump);
639 code = GET_CODE (cond);
641 if ((if_info->cond_earliest == if_info->jump || cond_complex)
642 && (normalize == 0 || STORE_FLAG_VALUE == normalize))
646 tmp = gen_rtx_fmt_ee (code, GET_MODE (x), XEXP (cond, 0),
648 tmp = gen_rtx_SET (VOIDmode, x, tmp);
651 tmp = emit_insn (tmp);
653 if (recog_memoized (tmp) >= 0)
659 if_info->cond_earliest = if_info->jump;
667 /* Don't even try if the comparison operands or the mode of X are weird. */
668 if (cond_complex || !SCALAR_INT_MODE_P (GET_MODE (x)))
671 return emit_store_flag (x, code, XEXP (cond, 0),
672 XEXP (cond, 1), VOIDmode,
673 (code == LTU || code == LEU
674 || code == GEU || code == GTU), normalize);
677 /* Emit instruction to move an rtx, possibly into STRICT_LOW_PART.
678 X is the destination/target and Y is the value to copy. */
681 noce_emit_move_insn (rtx x, rtx y)
683 enum machine_mode outmode, inmode;
687 if (GET_CODE (x) != STRICT_LOW_PART)
689 emit_move_insn (x, y);
694 inner = XEXP (outer, 0);
695 outmode = GET_MODE (outer);
696 inmode = GET_MODE (inner);
697 bitpos = SUBREG_BYTE (outer) * BITS_PER_UNIT;
698 store_bit_field (inner, GET_MODE_BITSIZE (outmode), bitpos, outmode, y,
699 GET_MODE_BITSIZE (inmode));
702 /* Unshare sequence SEQ produced by if conversion. We care to mark
703 all arguments that may be shared with outer instruction stream. */
705 unshare_ifcvt_sequence (struct noce_if_info *if_info, rtx seq)
707 set_used_flags (if_info->x);
708 set_used_flags (if_info->cond);
709 unshare_all_rtl_in_chain (seq);
712 /* Convert "if (a != b) x = a; else x = b" into "x = a" and
713 "if (a == b) x = a; else x = b" into "x = b". */
716 noce_try_move (struct noce_if_info *if_info)
718 rtx cond = if_info->cond;
719 enum rtx_code code = GET_CODE (cond);
722 if (code != NE && code != EQ)
725 /* This optimization isn't valid if either A or B could be a NaN
727 if (HONOR_NANS (GET_MODE (if_info->x))
728 || HONOR_SIGNED_ZEROS (GET_MODE (if_info->x)))
731 /* Check whether the operands of the comparison are A and in
733 if ((rtx_equal_p (if_info->a, XEXP (cond, 0))
734 && rtx_equal_p (if_info->b, XEXP (cond, 1)))
735 || (rtx_equal_p (if_info->a, XEXP (cond, 1))
736 && rtx_equal_p (if_info->b, XEXP (cond, 0))))
738 y = (code == EQ) ? if_info->a : if_info->b;
740 /* Avoid generating the move if the source is the destination. */
741 if (! rtx_equal_p (if_info->x, y))
744 noce_emit_move_insn (if_info->x, y);
746 unshare_ifcvt_sequence (if_info, seq);
749 /* Make sure that all of the instructions emitted are
750 recognizable. As an excersise for the reader, build
751 a general mechanism that allows proper placement of
752 required clobbers. */
753 for (y = seq; y ; y = NEXT_INSN (y))
754 if (recog_memoized (y) == -1)
757 emit_insn_before_setloc (seq, if_info->jump,
758 INSN_LOCATOR (if_info->insn_a));
765 /* Convert "if (test) x = 1; else x = 0".
767 Only try 0 and STORE_FLAG_VALUE here. Other combinations will be
768 tried in noce_try_store_flag_constants after noce_try_cmove has had
769 a go at the conversion. */
772 noce_try_store_flag (struct noce_if_info *if_info)
777 if (GET_CODE (if_info->b) == CONST_INT
778 && INTVAL (if_info->b) == STORE_FLAG_VALUE
779 && if_info->a == const0_rtx)
781 else if (if_info->b == const0_rtx
782 && GET_CODE (if_info->a) == CONST_INT
783 && INTVAL (if_info->a) == STORE_FLAG_VALUE
784 && (reversed_comparison_code (if_info->cond, if_info->jump)
792 target = noce_emit_store_flag (if_info, if_info->x, reversep, 0);
795 if (target != if_info->x)
796 noce_emit_move_insn (if_info->x, target);
799 unshare_ifcvt_sequence (if_info, seq);
801 emit_insn_before_setloc (seq, if_info->jump, INSN_LOCATOR (if_info->insn_a));
812 /* Convert "if (test) x = a; else x = b", for A and B constant. */
815 noce_try_store_flag_constants (struct noce_if_info *if_info)
819 HOST_WIDE_INT itrue, ifalse, diff, tmp;
820 int normalize, can_reverse;
821 enum machine_mode mode;
824 && GET_CODE (if_info->a) == CONST_INT
825 && GET_CODE (if_info->b) == CONST_INT)
827 mode = GET_MODE (if_info->x);
828 ifalse = INTVAL (if_info->a);
829 itrue = INTVAL (if_info->b);
831 /* Make sure we can represent the difference between the two values. */
832 if ((itrue - ifalse > 0)
833 != ((ifalse < 0) != (itrue < 0) ? ifalse < 0 : ifalse < itrue))
836 diff = trunc_int_for_mode (itrue - ifalse, mode);
838 can_reverse = (reversed_comparison_code (if_info->cond, if_info->jump)
842 if (diff == STORE_FLAG_VALUE || diff == -STORE_FLAG_VALUE)
844 else if (ifalse == 0 && exact_log2 (itrue) >= 0
845 && (STORE_FLAG_VALUE == 1
846 || BRANCH_COST >= 2))
848 else if (itrue == 0 && exact_log2 (ifalse) >= 0 && can_reverse
849 && (STORE_FLAG_VALUE == 1 || BRANCH_COST >= 2))
850 normalize = 1, reversep = 1;
852 && (STORE_FLAG_VALUE == -1
853 || BRANCH_COST >= 2))
855 else if (ifalse == -1 && can_reverse
856 && (STORE_FLAG_VALUE == -1 || BRANCH_COST >= 2))
857 normalize = -1, reversep = 1;
858 else if ((BRANCH_COST >= 2 && STORE_FLAG_VALUE == -1)
866 tmp = itrue; itrue = ifalse; ifalse = tmp;
867 diff = trunc_int_for_mode (-diff, mode);
871 target = noce_emit_store_flag (if_info, if_info->x, reversep, normalize);
878 /* if (test) x = 3; else x = 4;
879 => x = 3 + (test == 0); */
880 if (diff == STORE_FLAG_VALUE || diff == -STORE_FLAG_VALUE)
882 target = expand_simple_binop (mode,
883 (diff == STORE_FLAG_VALUE
885 GEN_INT (ifalse), target, if_info->x, 0,
889 /* if (test) x = 8; else x = 0;
890 => x = (test != 0) << 3; */
891 else if (ifalse == 0 && (tmp = exact_log2 (itrue)) >= 0)
893 target = expand_simple_binop (mode, ASHIFT,
894 target, GEN_INT (tmp), if_info->x, 0,
898 /* if (test) x = -1; else x = b;
899 => x = -(test != 0) | b; */
900 else if (itrue == -1)
902 target = expand_simple_binop (mode, IOR,
903 target, GEN_INT (ifalse), if_info->x, 0,
907 /* if (test) x = a; else x = b;
908 => x = (-(test != 0) & (b - a)) + a; */
911 target = expand_simple_binop (mode, AND,
912 target, GEN_INT (diff), if_info->x, 0,
915 target = expand_simple_binop (mode, PLUS,
916 target, GEN_INT (ifalse),
917 if_info->x, 0, OPTAB_WIDEN);
926 if (target != if_info->x)
927 noce_emit_move_insn (if_info->x, target);
930 unshare_ifcvt_sequence (if_info, seq);
933 if (seq_contains_jump (seq))
936 emit_insn_before_setloc (seq, if_info->jump, INSN_LOCATOR (if_info->insn_a));
944 /* Convert "if (test) foo++" into "foo += (test != 0)", and
945 similarly for "foo--". */
948 noce_try_addcc (struct noce_if_info *if_info)
951 int subtract, normalize;
954 && GET_CODE (if_info->a) == PLUS
955 && rtx_equal_p (XEXP (if_info->a, 0), if_info->b)
956 && (reversed_comparison_code (if_info->cond, if_info->jump)
959 rtx cond = if_info->cond;
960 enum rtx_code code = reversed_comparison_code (cond, if_info->jump);
962 /* First try to use addcc pattern. */
963 if (general_operand (XEXP (cond, 0), VOIDmode)
964 && general_operand (XEXP (cond, 1), VOIDmode))
967 target = emit_conditional_add (if_info->x, code,
972 XEXP (if_info->a, 1),
973 GET_MODE (if_info->x),
974 (code == LTU || code == GEU
975 || code == LEU || code == GTU));
978 if (target != if_info->x)
979 noce_emit_move_insn (if_info->x, target);
982 unshare_ifcvt_sequence (if_info, seq);
984 emit_insn_before_setloc (seq, if_info->jump,
985 INSN_LOCATOR (if_info->insn_a));
991 /* If that fails, construct conditional increment or decrement using
994 && (XEXP (if_info->a, 1) == const1_rtx
995 || XEXP (if_info->a, 1) == constm1_rtx))
998 if (STORE_FLAG_VALUE == INTVAL (XEXP (if_info->a, 1)))
999 subtract = 0, normalize = 0;
1000 else if (-STORE_FLAG_VALUE == INTVAL (XEXP (if_info->a, 1)))
1001 subtract = 1, normalize = 0;
1003 subtract = 0, normalize = INTVAL (XEXP (if_info->a, 1));
1006 target = noce_emit_store_flag (if_info,
1007 gen_reg_rtx (GET_MODE (if_info->x)),
1011 target = expand_simple_binop (GET_MODE (if_info->x),
1012 subtract ? MINUS : PLUS,
1013 if_info->b, target, if_info->x,
1017 if (target != if_info->x)
1018 noce_emit_move_insn (if_info->x, target);
1021 unshare_ifcvt_sequence (if_info, seq);
1024 if (seq_contains_jump (seq))
1027 emit_insn_before_setloc (seq, if_info->jump,
1028 INSN_LOCATOR (if_info->insn_a));
1039 /* Convert "if (test) x = 0;" to "x &= -(test == 0);" */
1042 noce_try_store_flag_mask (struct noce_if_info *if_info)
1048 if (! no_new_pseudos
1049 && (BRANCH_COST >= 2
1050 || STORE_FLAG_VALUE == -1)
1051 && ((if_info->a == const0_rtx
1052 && rtx_equal_p (if_info->b, if_info->x))
1053 || ((reversep = (reversed_comparison_code (if_info->cond,
1056 && if_info->b == const0_rtx
1057 && rtx_equal_p (if_info->a, if_info->x))))
1060 target = noce_emit_store_flag (if_info,
1061 gen_reg_rtx (GET_MODE (if_info->x)),
1064 target = expand_simple_binop (GET_MODE (if_info->x), AND,
1066 target, if_info->x, 0,
1071 if (target != if_info->x)
1072 noce_emit_move_insn (if_info->x, target);
1075 unshare_ifcvt_sequence (if_info, seq);
1078 if (seq_contains_jump (seq))
1081 emit_insn_before_setloc (seq, if_info->jump,
1082 INSN_LOCATOR (if_info->insn_a));
1093 /* Helper function for noce_try_cmove and noce_try_cmove_arith. */
1096 noce_emit_cmove (struct noce_if_info *if_info, rtx x, enum rtx_code code,
1097 rtx cmp_a, rtx cmp_b, rtx vfalse, rtx vtrue)
1099 /* If earliest == jump, try to build the cmove insn directly.
1100 This is helpful when combine has created some complex condition
1101 (like for alpha's cmovlbs) that we can't hope to regenerate
1102 through the normal interface. */
1104 if (if_info->cond_earliest == if_info->jump)
1108 tmp = gen_rtx_fmt_ee (code, GET_MODE (if_info->cond), cmp_a, cmp_b);
1109 tmp = gen_rtx_IF_THEN_ELSE (GET_MODE (x), tmp, vtrue, vfalse);
1110 tmp = gen_rtx_SET (VOIDmode, x, tmp);
1113 tmp = emit_insn (tmp);
1115 if (recog_memoized (tmp) >= 0)
1127 /* Don't even try if the comparison operands are weird. */
1128 if (! general_operand (cmp_a, GET_MODE (cmp_a))
1129 || ! general_operand (cmp_b, GET_MODE (cmp_b)))
1132 #if HAVE_conditional_move
1133 return emit_conditional_move (x, code, cmp_a, cmp_b, VOIDmode,
1134 vtrue, vfalse, GET_MODE (x),
1135 (code == LTU || code == GEU
1136 || code == LEU || code == GTU));
1138 /* We'll never get here, as noce_process_if_block doesn't call the
1139 functions involved. Ifdef code, however, should be discouraged
1140 because it leads to typos in the code not selected. However,
1141 emit_conditional_move won't exist either. */
1146 /* Try only simple constants and registers here. More complex cases
1147 are handled in noce_try_cmove_arith after noce_try_store_flag_arith
1148 has had a go at it. */
1151 noce_try_cmove (struct noce_if_info *if_info)
1156 if ((CONSTANT_P (if_info->a) || register_operand (if_info->a, VOIDmode))
1157 && (CONSTANT_P (if_info->b) || register_operand (if_info->b, VOIDmode)))
1161 code = GET_CODE (if_info->cond);
1162 target = noce_emit_cmove (if_info, if_info->x, code,
1163 XEXP (if_info->cond, 0),
1164 XEXP (if_info->cond, 1),
1165 if_info->a, if_info->b);
1169 if (target != if_info->x)
1170 noce_emit_move_insn (if_info->x, target);
1173 unshare_ifcvt_sequence (if_info, seq);
1175 emit_insn_before_setloc (seq, if_info->jump,
1176 INSN_LOCATOR (if_info->insn_a));
1189 /* Try more complex cases involving conditional_move. */
1192 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;
1252 /* If either operand is complex, load it into a register first.
1253 The best way to do this is to copy the original insn. In this
1254 way we preserve any clobbers etc that the insn may have had.
1255 This is of course not possible in the IS_MEM case. */
1256 if (! general_operand (a, GET_MODE (a)))
1261 goto end_seq_and_fail;
1265 tmp = gen_reg_rtx (GET_MODE (a));
1266 tmp = emit_insn (gen_rtx_SET (VOIDmode, tmp, a));
1269 goto end_seq_and_fail;
1272 a = gen_reg_rtx (GET_MODE (a));
1273 tmp = copy_rtx (insn_a);
1274 set = single_set (tmp);
1276 tmp = emit_insn (PATTERN (tmp));
1278 if (recog_memoized (tmp) < 0)
1279 goto end_seq_and_fail;
1281 if (! general_operand (b, GET_MODE (b)))
1286 goto end_seq_and_fail;
1290 tmp = gen_reg_rtx (GET_MODE (b));
1291 tmp = emit_insn (gen_rtx_SET (VOIDmode,
1296 goto end_seq_and_fail;
1299 b = gen_reg_rtx (GET_MODE (b));
1300 tmp = copy_rtx (insn_b);
1301 set = single_set (tmp);
1303 tmp = emit_insn (PATTERN (tmp));
1305 if (recog_memoized (tmp) < 0)
1306 goto end_seq_and_fail;
1309 target = noce_emit_cmove (if_info, x, code, XEXP (if_info->cond, 0),
1310 XEXP (if_info->cond, 1), a, b);
1313 goto end_seq_and_fail;
1315 /* If we're handling a memory for above, emit the load now. */
1318 tmp = gen_rtx_MEM (GET_MODE (if_info->x), target);
1320 /* Copy over flags as appropriate. */
1321 if (MEM_VOLATILE_P (if_info->a) || MEM_VOLATILE_P (if_info->b))
1322 MEM_VOLATILE_P (tmp) = 1;
1323 if (MEM_IN_STRUCT_P (if_info->a) && MEM_IN_STRUCT_P (if_info->b))
1324 MEM_IN_STRUCT_P (tmp) = 1;
1325 if (MEM_SCALAR_P (if_info->a) && MEM_SCALAR_P (if_info->b))
1326 MEM_SCALAR_P (tmp) = 1;
1327 if (MEM_ALIAS_SET (if_info->a) == MEM_ALIAS_SET (if_info->b))
1328 set_mem_alias_set (tmp, MEM_ALIAS_SET (if_info->a));
1330 MIN (MEM_ALIGN (if_info->a), MEM_ALIGN (if_info->b)));
1332 noce_emit_move_insn (if_info->x, tmp);
1334 else if (target != x)
1335 noce_emit_move_insn (x, target);
1338 unshare_ifcvt_sequence (if_info, tmp);
1340 emit_insn_before_setloc (tmp, if_info->jump, INSN_LOCATOR (if_info->insn_a));
1348 /* For most cases, the simplified condition we found is the best
1349 choice, but this is not the case for the min/max/abs transforms.
1350 For these we wish to know that it is A or B in the condition. */
1353 noce_get_alt_condition (struct noce_if_info *if_info, rtx target,
1356 rtx cond, set, insn;
1359 /* If target is already mentioned in the known condition, return it. */
1360 if (reg_mentioned_p (target, if_info->cond))
1362 *earliest = if_info->cond_earliest;
1363 return if_info->cond;
1366 set = pc_set (if_info->jump);
1367 cond = XEXP (SET_SRC (set), 0);
1369 = GET_CODE (XEXP (SET_SRC (set), 2)) == LABEL_REF
1370 && XEXP (XEXP (SET_SRC (set), 2), 0) == JUMP_LABEL (if_info->jump);
1372 /* If we're looking for a constant, try to make the conditional
1373 have that constant in it. There are two reasons why it may
1374 not have the constant we want:
1376 1. GCC may have needed to put the constant in a register, because
1377 the target can't compare directly against that constant. For
1378 this case, we look for a SET immediately before the comparison
1379 that puts a constant in that register.
1381 2. GCC may have canonicalized the conditional, for example
1382 replacing "if x < 4" with "if x <= 3". We can undo that (or
1383 make equivalent types of changes) to get the constants we need
1384 if they're off by one in the right direction. */
1386 if (GET_CODE (target) == CONST_INT)
1388 enum rtx_code code = GET_CODE (if_info->cond);
1389 rtx op_a = XEXP (if_info->cond, 0);
1390 rtx op_b = XEXP (if_info->cond, 1);
1393 /* First, look to see if we put a constant in a register. */
1394 prev_insn = PREV_INSN (if_info->cond_earliest);
1396 && INSN_P (prev_insn)
1397 && GET_CODE (PATTERN (prev_insn)) == SET)
1399 rtx src = find_reg_equal_equiv_note (prev_insn);
1401 src = SET_SRC (PATTERN (prev_insn));
1402 if (GET_CODE (src) == CONST_INT)
1404 if (rtx_equal_p (op_a, SET_DEST (PATTERN (prev_insn))))
1406 else if (rtx_equal_p (op_b, SET_DEST (PATTERN (prev_insn))))
1409 if (GET_CODE (op_a) == CONST_INT)
1414 code = swap_condition (code);
1419 /* Now, look to see if we can get the right constant by
1420 adjusting the conditional. */
1421 if (GET_CODE (op_b) == CONST_INT)
1423 HOST_WIDE_INT desired_val = INTVAL (target);
1424 HOST_WIDE_INT actual_val = INTVAL (op_b);
1429 if (actual_val == desired_val + 1)
1432 op_b = GEN_INT (desired_val);
1436 if (actual_val == desired_val - 1)
1439 op_b = GEN_INT (desired_val);
1443 if (actual_val == desired_val - 1)
1446 op_b = GEN_INT (desired_val);
1450 if (actual_val == desired_val + 1)
1453 op_b = GEN_INT (desired_val);
1461 /* If we made any changes, generate a new conditional that is
1462 equivalent to what we started with, but has the right
1464 if (code != GET_CODE (if_info->cond)
1465 || op_a != XEXP (if_info->cond, 0)
1466 || op_b != XEXP (if_info->cond, 1))
1468 cond = gen_rtx_fmt_ee (code, GET_MODE (cond), op_a, op_b);
1469 *earliest = if_info->cond_earliest;
1474 cond = canonicalize_condition (if_info->jump, cond, reverse,
1475 earliest, target, false);
1476 if (! cond || ! reg_mentioned_p (target, cond))
1479 /* We almost certainly searched back to a different place.
1480 Need to re-verify correct lifetimes. */
1482 /* X may not be mentioned in the range (cond_earliest, jump]. */
1483 for (insn = if_info->jump; insn != *earliest; insn = PREV_INSN (insn))
1484 if (INSN_P (insn) && reg_overlap_mentioned_p (if_info->x, PATTERN (insn)))
1487 /* A and B may not be modified in the range [cond_earliest, jump). */
1488 for (insn = *earliest; insn != if_info->jump; insn = NEXT_INSN (insn))
1490 && (modified_in_p (if_info->a, insn)
1491 || modified_in_p (if_info->b, insn)))
1497 /* Convert "if (a < b) x = a; else x = b;" to "x = min(a, b);", etc. */
1500 noce_try_minmax (struct noce_if_info *if_info)
1502 rtx cond, earliest, target, seq;
1503 enum rtx_code code, op;
1506 /* ??? Can't guarantee that expand_binop won't create pseudos. */
1510 /* ??? Reject modes with NaNs or signed zeros since we don't know how
1511 they will be resolved with an SMIN/SMAX. It wouldn't be too hard
1512 to get the target to tell us... */
1513 if (HONOR_SIGNED_ZEROS (GET_MODE (if_info->x))
1514 || HONOR_NANS (GET_MODE (if_info->x)))
1517 cond = noce_get_alt_condition (if_info, if_info->a, &earliest);
1521 /* Verify the condition is of the form we expect, and canonicalize
1522 the comparison code. */
1523 code = GET_CODE (cond);
1524 if (rtx_equal_p (XEXP (cond, 0), if_info->a))
1526 if (! rtx_equal_p (XEXP (cond, 1), if_info->b))
1529 else if (rtx_equal_p (XEXP (cond, 1), if_info->a))
1531 if (! rtx_equal_p (XEXP (cond, 0), if_info->b))
1533 code = swap_condition (code);
1538 /* Determine what sort of operation this is. Note that the code is for
1539 a taken branch, so the code->operation mapping appears backwards. */
1572 target = expand_simple_binop (GET_MODE (if_info->x), op,
1573 if_info->a, if_info->b,
1574 if_info->x, unsignedp, OPTAB_WIDEN);
1580 if (target != if_info->x)
1581 noce_emit_move_insn (if_info->x, target);
1584 unshare_ifcvt_sequence (if_info, seq);
1587 if (seq_contains_jump (seq))
1590 emit_insn_before_setloc (seq, if_info->jump, INSN_LOCATOR (if_info->insn_a));
1591 if_info->cond = cond;
1592 if_info->cond_earliest = earliest;
1597 /* Convert "if (a < 0) x = -a; else x = a;" to "x = abs(a);", etc. */
1600 noce_try_abs (struct noce_if_info *if_info)
1602 rtx cond, earliest, target, seq, a, b, c;
1605 /* ??? Can't guarantee that expand_binop won't create pseudos. */
1609 /* Recognize A and B as constituting an ABS or NABS. */
1612 if (GET_CODE (a) == NEG && rtx_equal_p (XEXP (a, 0), b))
1614 else if (GET_CODE (b) == NEG && rtx_equal_p (XEXP (b, 0), a))
1616 c = a; a = b; b = c;
1622 cond = noce_get_alt_condition (if_info, b, &earliest);
1626 /* Verify the condition is of the form we expect. */
1627 if (rtx_equal_p (XEXP (cond, 0), b))
1629 else if (rtx_equal_p (XEXP (cond, 1), b))
1634 /* Verify that C is zero. Search backward through the block for
1635 a REG_EQUAL note if necessary. */
1638 rtx insn, note = NULL;
1639 for (insn = earliest;
1640 insn != BB_HEAD (if_info->test_bb);
1641 insn = PREV_INSN (insn))
1643 && ((note = find_reg_note (insn, REG_EQUAL, c))
1644 || (note = find_reg_note (insn, REG_EQUIV, c))))
1650 if (GET_CODE (c) == MEM
1651 && GET_CODE (XEXP (c, 0)) == SYMBOL_REF
1652 && CONSTANT_POOL_ADDRESS_P (XEXP (c, 0)))
1653 c = get_pool_constant (XEXP (c, 0));
1655 /* Work around funny ideas get_condition has wrt canonicalization.
1656 Note that these rtx constants are known to be CONST_INT, and
1657 therefore imply integer comparisons. */
1658 if (c == constm1_rtx && GET_CODE (cond) == GT)
1660 else if (c == const1_rtx && GET_CODE (cond) == LT)
1662 else if (c != CONST0_RTX (GET_MODE (b)))
1665 /* Determine what sort of operation this is. */
1666 switch (GET_CODE (cond))
1685 target = expand_abs_nojump (GET_MODE (if_info->x), b, if_info->x, 1);
1687 /* ??? It's a quandary whether cmove would be better here, especially
1688 for integers. Perhaps combine will clean things up. */
1689 if (target && negate)
1690 target = expand_simple_unop (GET_MODE (target), NEG, target, if_info->x, 0);
1698 if (target != if_info->x)
1699 noce_emit_move_insn (if_info->x, target);
1702 unshare_ifcvt_sequence (if_info, seq);
1705 if (seq_contains_jump (seq))
1708 emit_insn_before_setloc (seq, if_info->jump, INSN_LOCATOR (if_info->insn_a));
1709 if_info->cond = cond;
1710 if_info->cond_earliest = earliest;
1715 /* Convert "if (m < 0) x = b; else x = 0;" to "x = (m >> C) & b;". */
1718 noce_try_sign_mask (struct noce_if_info *if_info)
1720 rtx cond, t, m, c, seq;
1721 enum machine_mode mode;
1727 cond = if_info->cond;
1728 code = GET_CODE (cond);
1733 if (if_info->a == const0_rtx)
1735 if ((code == LT && c == const0_rtx)
1736 || (code == LE && c == constm1_rtx))
1739 else if (if_info->b == const0_rtx)
1741 if ((code == GE && c == const0_rtx)
1742 || (code == GT && c == constm1_rtx))
1746 if (! t || side_effects_p (t))
1749 /* We currently don't handle different modes. */
1750 mode = GET_MODE (t);
1751 if (GET_MODE (m) != mode)
1754 /* This is only profitable if T is cheap. */
1755 if (rtx_cost (t, SET) >= COSTS_N_INSNS (2))
1759 c = gen_int_mode (GET_MODE_BITSIZE (mode) - 1, mode);
1760 m = expand_binop (mode, ashr_optab, m, c, NULL_RTX, 0, OPTAB_DIRECT);
1761 t = m ? expand_binop (mode, and_optab, m, t, NULL_RTX, 0, OPTAB_DIRECT)
1770 noce_emit_move_insn (if_info->x, t);
1772 unshare_ifcvt_sequence (if_info, seq);
1774 emit_insn_before_setloc (seq, if_info->jump,
1775 INSN_LOCATOR (if_info->insn_a));
1780 /* Similar to get_condition, only the resulting condition must be
1781 valid at JUMP, instead of at EARLIEST. */
1784 noce_get_condition (rtx jump, rtx *earliest)
1786 rtx cond, set, tmp, insn;
1789 if (! any_condjump_p (jump))
1792 set = pc_set (jump);
1794 /* If this branches to JUMP_LABEL when the condition is false,
1795 reverse the condition. */
1796 reverse = (GET_CODE (XEXP (SET_SRC (set), 2)) == LABEL_REF
1797 && XEXP (XEXP (SET_SRC (set), 2), 0) == JUMP_LABEL (jump));
1799 /* If the condition variable is a register and is MODE_INT, accept it. */
1801 cond = XEXP (SET_SRC (set), 0);
1802 tmp = XEXP (cond, 0);
1803 if (REG_P (tmp) && GET_MODE_CLASS (GET_MODE (tmp)) == MODE_INT)
1808 cond = gen_rtx_fmt_ee (reverse_condition (GET_CODE (cond)),
1809 GET_MODE (cond), tmp, XEXP (cond, 1));
1813 /* Otherwise, fall back on canonicalize_condition to do the dirty
1814 work of manipulating MODE_CC values and COMPARE rtx codes. */
1816 tmp = canonicalize_condition (jump, cond, reverse, earliest, NULL_RTX,
1821 /* We are going to insert code before JUMP, not before EARLIEST.
1822 We must therefore be certain that the given condition is valid
1823 at JUMP by virtue of not having been modified since. */
1824 for (insn = *earliest; insn != jump; insn = NEXT_INSN (insn))
1825 if (INSN_P (insn) && modified_in_p (tmp, insn))
1830 /* The condition was modified. See if we can get a partial result
1831 that doesn't follow all the reversals. Perhaps combine can fold
1832 them together later. */
1833 tmp = XEXP (tmp, 0);
1834 if (!REG_P (tmp) || GET_MODE_CLASS (GET_MODE (tmp)) != MODE_INT)
1836 tmp = canonicalize_condition (jump, cond, reverse, earliest, tmp,
1841 /* For sanity's sake, re-validate the new result. */
1842 for (insn = *earliest; insn != jump; insn = NEXT_INSN (insn))
1843 if (INSN_P (insn) && modified_in_p (tmp, insn))
1849 /* Return true if OP is ok for if-then-else processing. */
1852 noce_operand_ok (rtx op)
1854 /* We special-case memories, so handle any of them with
1855 no address side effects. */
1856 if (GET_CODE (op) == MEM)
1857 return ! side_effects_p (XEXP (op, 0));
1859 if (side_effects_p (op))
1862 return ! may_trap_p (op);
1865 /* Given a simple IF-THEN or IF-THEN-ELSE block, attempt to convert it
1866 without using conditional execution. Return TRUE if we were
1867 successful at converting the block. */
1870 noce_process_if_block (struct ce_if_block * ce_info)
1872 basic_block test_bb = ce_info->test_bb; /* test block */
1873 basic_block then_bb = ce_info->then_bb; /* THEN */
1874 basic_block else_bb = ce_info->else_bb; /* ELSE or NULL */
1875 struct noce_if_info if_info;
1878 rtx orig_x, x, a, b;
1881 /* We're looking for patterns of the form
1883 (1) if (...) x = a; else x = b;
1884 (2) x = b; if (...) x = a;
1885 (3) if (...) x = a; // as if with an initial x = x.
1887 The later patterns require jumps to be more expensive.
1889 ??? For future expansion, look for multiple X in such patterns. */
1891 /* If test is comprised of && or || elements, don't handle it unless it is
1892 the special case of && elements without an ELSE block. */
1893 if (ce_info->num_multiple_test_blocks)
1895 if (else_bb || ! ce_info->and_and_p)
1898 ce_info->test_bb = test_bb = ce_info->last_test_bb;
1899 ce_info->num_multiple_test_blocks = 0;
1900 ce_info->num_and_and_blocks = 0;
1901 ce_info->num_or_or_blocks = 0;
1904 /* If this is not a standard conditional jump, we can't parse it. */
1905 jump = BB_END (test_bb);
1906 cond = noce_get_condition (jump, &if_info.cond_earliest);
1910 /* If the conditional jump is more than just a conditional
1911 jump, then we can not do if-conversion on this block. */
1912 if (! onlyjump_p (jump))
1915 /* We must be comparing objects whose modes imply the size. */
1916 if (GET_MODE (XEXP (cond, 0)) == BLKmode)
1919 /* Look for one of the potential sets. */
1920 insn_a = first_active_insn (then_bb);
1922 || insn_a != last_active_insn (then_bb, FALSE)
1923 || (set_a = single_set (insn_a)) == NULL_RTX)
1926 x = SET_DEST (set_a);
1927 a = SET_SRC (set_a);
1929 /* Look for the other potential set. Make sure we've got equivalent
1931 /* ??? This is overconservative. Storing to two different mems is
1932 as easy as conditionally computing the address. Storing to a
1933 single mem merely requires a scratch memory to use as one of the
1934 destination addresses; often the memory immediately below the
1935 stack pointer is available for this. */
1939 insn_b = first_active_insn (else_bb);
1941 || insn_b != last_active_insn (else_bb, FALSE)
1942 || (set_b = single_set (insn_b)) == NULL_RTX
1943 || ! rtx_equal_p (x, SET_DEST (set_b)))
1948 insn_b = prev_nonnote_insn (if_info.cond_earliest);
1949 /* We're going to be moving the evaluation of B down from above
1950 COND_EARLIEST to JUMP. Make sure the relevant data is still
1953 || GET_CODE (insn_b) != INSN
1954 || (set_b = single_set (insn_b)) == NULL_RTX
1955 || ! rtx_equal_p (x, SET_DEST (set_b))
1956 || reg_overlap_mentioned_p (x, SET_SRC (set_b))
1957 || modified_between_p (SET_SRC (set_b),
1958 PREV_INSN (if_info.cond_earliest), jump)
1959 /* Likewise with X. In particular this can happen when
1960 noce_get_condition looks farther back in the instruction
1961 stream than one might expect. */
1962 || reg_overlap_mentioned_p (x, cond)
1963 || reg_overlap_mentioned_p (x, a)
1964 || modified_between_p (x, PREV_INSN (if_info.cond_earliest), jump))
1965 insn_b = set_b = NULL_RTX;
1968 /* If x has side effects then only the if-then-else form is safe to
1969 convert. But even in that case we would need to restore any notes
1970 (such as REG_INC) at then end. That can be tricky if
1971 noce_emit_move_insn expands to more than one insn, so disable the
1972 optimization entirely for now if there are side effects. */
1973 if (side_effects_p (x))
1976 b = (set_b ? SET_SRC (set_b) : x);
1978 /* Only operate on register destinations, and even then avoid extending
1979 the lifetime of hard registers on small register class machines. */
1982 || (SMALL_REGISTER_CLASSES
1983 && REGNO (x) < FIRST_PSEUDO_REGISTER))
1985 if (no_new_pseudos || GET_MODE (x) == BLKmode)
1987 x = gen_reg_rtx (GET_MODE (GET_CODE (x) == STRICT_LOW_PART
1988 ? XEXP (x, 0) : x));
1991 /* Don't operate on sources that may trap or are volatile. */
1992 if (! noce_operand_ok (a) || ! noce_operand_ok (b))
1995 /* Set up the info block for our subroutines. */
1996 if_info.test_bb = test_bb;
1997 if_info.cond = cond;
1998 if_info.jump = jump;
1999 if_info.insn_a = insn_a;
2000 if_info.insn_b = insn_b;
2005 /* Try optimizations in some approximation of a useful order. */
2006 /* ??? Should first look to see if X is live incoming at all. If it
2007 isn't, we don't need anything but an unconditional set. */
2009 /* Look and see if A and B are really the same. Avoid creating silly
2010 cmove constructs that no one will fix up later. */
2011 if (rtx_equal_p (a, b))
2013 /* If we have an INSN_B, we don't have to create any new rtl. Just
2014 move the instruction that we already have. If we don't have an
2015 INSN_B, that means that A == X, and we've got a noop move. In
2016 that case don't do anything and let the code below delete INSN_A. */
2017 if (insn_b && else_bb)
2021 if (else_bb && insn_b == BB_END (else_bb))
2022 BB_END (else_bb) = PREV_INSN (insn_b);
2023 reorder_insns (insn_b, insn_b, PREV_INSN (jump));
2025 /* If there was a REG_EQUAL note, delete it since it may have been
2026 true due to this insn being after a jump. */
2027 if ((note = find_reg_note (insn_b, REG_EQUAL, NULL_RTX)) != 0)
2028 remove_note (insn_b, note);
2032 /* If we have "x = b; if (...) x = a;", and x has side-effects, then
2033 x must be executed twice. */
2034 else if (insn_b && side_effects_p (orig_x))
2041 /* Disallow the "if (...) x = a;" form (with an implicit "else x = x;")
2042 for most optimizations if writing to x may trap, i.e. it's a memory
2043 other than a static var or a stack slot. */
2045 && GET_CODE (orig_x) == MEM
2046 && ! MEM_NOTRAP_P (orig_x)
2047 && rtx_addr_can_trap_p (XEXP (orig_x, 0)))
2049 if (HAVE_conditional_move)
2051 if (noce_try_cmove (&if_info))
2053 if (! HAVE_conditional_execution
2054 && noce_try_cmove_arith (&if_info))
2060 if (noce_try_move (&if_info))
2062 if (noce_try_store_flag (&if_info))
2064 if (noce_try_minmax (&if_info))
2066 if (noce_try_abs (&if_info))
2068 if (HAVE_conditional_move
2069 && noce_try_cmove (&if_info))
2071 if (! HAVE_conditional_execution)
2073 if (noce_try_store_flag_constants (&if_info))
2075 if (noce_try_addcc (&if_info))
2077 if (noce_try_store_flag_mask (&if_info))
2079 if (HAVE_conditional_move
2080 && noce_try_cmove_arith (&if_info))
2082 if (noce_try_sign_mask (&if_info))
2089 /* The original sets may now be killed. */
2090 delete_insn (insn_a);
2092 /* Several special cases here: First, we may have reused insn_b above,
2093 in which case insn_b is now NULL. Second, we want to delete insn_b
2094 if it came from the ELSE block, because follows the now correct
2095 write that appears in the TEST block. However, if we got insn_b from
2096 the TEST block, it may in fact be loading data needed for the comparison.
2097 We'll let life_analysis remove the insn if it's really dead. */
2098 if (insn_b && else_bb)
2099 delete_insn (insn_b);
2101 /* The new insns will have been inserted immediately before the jump. We
2102 should be able to remove the jump with impunity, but the condition itself
2103 may have been modified by gcse to be shared across basic blocks. */
2106 /* If we used a temporary, fix it up now. */
2110 noce_emit_move_insn (orig_x, x);
2111 insn_b = get_insns ();
2112 set_used_flags (orig_x);
2113 unshare_all_rtl_in_chain (insn_b);
2116 emit_insn_after_setloc (insn_b, BB_END (test_bb), INSN_LOCATOR (insn_a));
2119 /* Merge the blocks! */
2120 merge_if_block (ce_info);
2125 /* Attempt to convert an IF-THEN or IF-THEN-ELSE block into
2126 straight line code. Return true if successful. */
2129 process_if_block (struct ce_if_block * ce_info)
2131 if (! reload_completed
2132 && noce_process_if_block (ce_info))
2135 if (HAVE_conditional_execution && reload_completed)
2137 /* If we have && and || tests, try to first handle combining the && and
2138 || tests into the conditional code, and if that fails, go back and
2139 handle it without the && and ||, which at present handles the && case
2140 if there was no ELSE block. */
2141 if (cond_exec_process_if_block (ce_info, TRUE))
2144 if (ce_info->num_multiple_test_blocks)
2148 if (cond_exec_process_if_block (ce_info, FALSE))
2156 /* Merge the blocks and mark for local life update. */
2159 merge_if_block (struct ce_if_block * ce_info)
2161 basic_block test_bb = ce_info->test_bb; /* last test block */
2162 basic_block then_bb = ce_info->then_bb; /* THEN */
2163 basic_block else_bb = ce_info->else_bb; /* ELSE or NULL */
2164 basic_block join_bb = ce_info->join_bb; /* join block */
2165 basic_block combo_bb;
2167 /* All block merging is done into the lower block numbers. */
2171 /* Merge any basic blocks to handle && and || subtests. Each of
2172 the blocks are on the fallthru path from the predecessor block. */
2173 if (ce_info->num_multiple_test_blocks > 0)
2175 basic_block bb = test_bb;
2176 basic_block last_test_bb = ce_info->last_test_bb;
2177 basic_block fallthru = block_fallthru (bb);
2182 fallthru = block_fallthru (bb);
2183 merge_blocks (combo_bb, bb);
2186 while (bb != last_test_bb);
2189 /* Merge TEST block into THEN block. Normally the THEN block won't have a
2190 label, but it might if there were || tests. That label's count should be
2191 zero, and it normally should be removed. */
2195 if (combo_bb->global_live_at_end)
2196 COPY_REG_SET (combo_bb->global_live_at_end,
2197 then_bb->global_live_at_end);
2198 merge_blocks (combo_bb, then_bb);
2202 /* The ELSE block, if it existed, had a label. That label count
2203 will almost always be zero, but odd things can happen when labels
2204 get their addresses taken. */
2207 merge_blocks (combo_bb, else_bb);
2211 /* If there was no join block reported, that means it was not adjacent
2212 to the others, and so we cannot merge them. */
2216 rtx last = BB_END (combo_bb);
2218 /* The outgoing edge for the current COMBO block should already
2219 be correct. Verify this. */
2220 if (combo_bb->succ == NULL_EDGE)
2222 if (find_reg_note (last, REG_NORETURN, NULL))
2224 else if (GET_CODE (last) == INSN
2225 && GET_CODE (PATTERN (last)) == TRAP_IF
2226 && TRAP_CONDITION (PATTERN (last)) == const_true_rtx)
2232 /* There should still be something at the end of the THEN or ELSE
2233 blocks taking us to our final destination. */
2234 else if (GET_CODE (last) == JUMP_INSN)
2236 else if (combo_bb->succ->dest == EXIT_BLOCK_PTR
2237 && GET_CODE (last) == CALL_INSN
2238 && SIBLING_CALL_P (last))
2240 else if ((combo_bb->succ->flags & EDGE_EH)
2241 && can_throw_internal (last))
2247 /* The JOIN block may have had quite a number of other predecessors too.
2248 Since we've already merged the TEST, THEN and ELSE blocks, we should
2249 have only one remaining edge from our if-then-else diamond. If there
2250 is more than one remaining edge, it must come from elsewhere. There
2251 may be zero incoming edges if the THEN block didn't actually join
2252 back up (as with a call to abort). */
2253 else if ((join_bb->pred == NULL
2254 || join_bb->pred->pred_next == NULL)
2255 && join_bb != EXIT_BLOCK_PTR)
2257 /* We can merge the JOIN. */
2258 if (combo_bb->global_live_at_end)
2259 COPY_REG_SET (combo_bb->global_live_at_end,
2260 join_bb->global_live_at_end);
2262 merge_blocks (combo_bb, join_bb);
2267 /* We cannot merge the JOIN. */
2269 /* The outgoing edge for the current COMBO block should already
2270 be correct. Verify this. */
2271 if (combo_bb->succ->succ_next != NULL_EDGE
2272 || combo_bb->succ->dest != join_bb)
2275 /* Remove the jump and cruft from the end of the COMBO block. */
2276 if (join_bb != EXIT_BLOCK_PTR)
2277 tidy_fallthru_edge (combo_bb->succ);
2280 num_updated_if_blocks++;
2283 /* Find a block ending in a simple IF condition and try to transform it
2284 in some way. When converting a multi-block condition, put the new code
2285 in the first such block and delete the rest. Return a pointer to this
2286 first block if some transformation was done. Return NULL otherwise. */
2289 find_if_header (basic_block test_bb, int pass)
2291 ce_if_block_t ce_info;
2295 /* The kind of block we're looking for has exactly two successors. */
2296 if ((then_edge = test_bb->succ) == NULL_EDGE
2297 || (else_edge = then_edge->succ_next) == NULL_EDGE
2298 || else_edge->succ_next != NULL_EDGE)
2301 /* Neither edge should be abnormal. */
2302 if ((then_edge->flags & EDGE_COMPLEX)
2303 || (else_edge->flags & EDGE_COMPLEX))
2306 /* Nor exit the loop. */
2307 if ((then_edge->flags & EDGE_LOOP_EXIT)
2308 || (else_edge->flags & EDGE_LOOP_EXIT))
2311 /* The THEN edge is canonically the one that falls through. */
2312 if (then_edge->flags & EDGE_FALLTHRU)
2314 else if (else_edge->flags & EDGE_FALLTHRU)
2317 else_edge = then_edge;
2321 /* Otherwise this must be a multiway branch of some sort. */
2324 memset (&ce_info, '\0', sizeof (ce_info));
2325 ce_info.test_bb = test_bb;
2326 ce_info.then_bb = then_edge->dest;
2327 ce_info.else_bb = else_edge->dest;
2328 ce_info.pass = pass;
2330 #ifdef IFCVT_INIT_EXTRA_FIELDS
2331 IFCVT_INIT_EXTRA_FIELDS (&ce_info);
2334 if (find_if_block (&ce_info))
2337 if (HAVE_trap && HAVE_conditional_trap
2338 && find_cond_trap (test_bb, then_edge, else_edge))
2341 if (dom_computed[CDI_POST_DOMINATORS] >= DOM_NO_FAST_QUERY
2342 && (! HAVE_conditional_execution || reload_completed))
2344 if (find_if_case_1 (test_bb, then_edge, else_edge))
2346 if (find_if_case_2 (test_bb, then_edge, else_edge))
2354 fprintf (dump_file, "Conversion succeeded on pass %d.\n", pass);
2355 return ce_info.test_bb;
2358 /* Return true if a block has two edges, one of which falls through to the next
2359 block, and the other jumps to a specific block, so that we can tell if the
2360 block is part of an && test or an || test. Returns either -1 or the number
2361 of non-note, non-jump, non-USE/CLOBBER insns in the block. */
2364 block_jumps_and_fallthru_p (basic_block cur_bb, basic_block target_bb)
2367 int fallthru_p = FALSE;
2373 if (!cur_bb || !target_bb)
2376 /* If no edges, obviously it doesn't jump or fallthru. */
2377 if (cur_bb->succ == NULL_EDGE)
2380 for (cur_edge = cur_bb->succ;
2381 cur_edge != NULL_EDGE;
2382 cur_edge = cur_edge->succ_next)
2384 if (cur_edge->flags & EDGE_COMPLEX)
2385 /* Anything complex isn't what we want. */
2388 else if (cur_edge->flags & EDGE_FALLTHRU)
2391 else if (cur_edge->dest == target_bb)
2398 if ((jump_p & fallthru_p) == 0)
2401 /* Don't allow calls in the block, since this is used to group && and ||
2402 together for conditional execution support. ??? we should support
2403 conditional execution support across calls for IA-64 some day, but
2404 for now it makes the code simpler. */
2405 end = BB_END (cur_bb);
2406 insn = BB_HEAD (cur_bb);
2408 while (insn != NULL_RTX)
2410 if (GET_CODE (insn) == CALL_INSN)
2414 && GET_CODE (insn) != JUMP_INSN
2415 && GET_CODE (PATTERN (insn)) != USE
2416 && GET_CODE (PATTERN (insn)) != CLOBBER)
2422 insn = NEXT_INSN (insn);
2428 /* Determine if a given basic block heads a simple IF-THEN or IF-THEN-ELSE
2429 block. If so, we'll try to convert the insns to not require the branch.
2430 Return TRUE if we were successful at converting the block. */
2433 find_if_block (struct ce_if_block * ce_info)
2435 basic_block test_bb = ce_info->test_bb;
2436 basic_block then_bb = ce_info->then_bb;
2437 basic_block else_bb = ce_info->else_bb;
2438 basic_block join_bb = NULL_BLOCK;
2439 edge then_succ = then_bb->succ;
2440 edge else_succ = else_bb->succ;
2441 int then_predecessors;
2442 int else_predecessors;
2446 ce_info->last_test_bb = test_bb;
2448 /* Discover if any fall through predecessors of the current test basic block
2449 were && tests (which jump to the else block) or || tests (which jump to
2451 if (HAVE_conditional_execution && reload_completed
2452 && test_bb->pred != NULL_EDGE
2453 && test_bb->pred->pred_next == NULL_EDGE
2454 && test_bb->pred->flags == EDGE_FALLTHRU)
2456 basic_block bb = test_bb->pred->src;
2457 basic_block target_bb;
2458 int max_insns = MAX_CONDITIONAL_EXECUTE;
2461 /* Determine if the preceding block is an && or || block. */
2462 if ((n_insns = block_jumps_and_fallthru_p (bb, else_bb)) >= 0)
2464 ce_info->and_and_p = TRUE;
2465 target_bb = else_bb;
2467 else if ((n_insns = block_jumps_and_fallthru_p (bb, then_bb)) >= 0)
2469 ce_info->and_and_p = FALSE;
2470 target_bb = then_bb;
2473 target_bb = NULL_BLOCK;
2475 if (target_bb && n_insns <= max_insns)
2477 int total_insns = 0;
2480 ce_info->last_test_bb = test_bb;
2482 /* Found at least one && or || block, look for more. */
2485 ce_info->test_bb = test_bb = bb;
2486 total_insns += n_insns;
2489 if (bb->pred == NULL_EDGE || bb->pred->pred_next != NULL_EDGE)
2493 n_insns = block_jumps_and_fallthru_p (bb, target_bb);
2495 while (n_insns >= 0 && (total_insns + n_insns) <= max_insns);
2497 ce_info->num_multiple_test_blocks = blocks;
2498 ce_info->num_multiple_test_insns = total_insns;
2500 if (ce_info->and_and_p)
2501 ce_info->num_and_and_blocks = blocks;
2503 ce_info->num_or_or_blocks = blocks;
2507 /* Count the number of edges the THEN and ELSE blocks have. */
2508 then_predecessors = 0;
2509 for (cur_edge = then_bb->pred;
2510 cur_edge != NULL_EDGE;
2511 cur_edge = cur_edge->pred_next)
2513 then_predecessors++;
2514 if (cur_edge->flags & EDGE_COMPLEX)
2518 else_predecessors = 0;
2519 for (cur_edge = else_bb->pred;
2520 cur_edge != NULL_EDGE;
2521 cur_edge = cur_edge->pred_next)
2523 else_predecessors++;
2524 if (cur_edge->flags & EDGE_COMPLEX)
2528 /* The THEN block of an IF-THEN combo must have exactly one predecessor,
2529 other than any || blocks which jump to the THEN block. */
2530 if ((then_predecessors - ce_info->num_or_or_blocks) != 1)
2533 /* The THEN block of an IF-THEN combo must have zero or one successors. */
2534 if (then_succ != NULL_EDGE
2535 && (then_succ->succ_next != NULL_EDGE
2536 || (then_succ->flags & EDGE_COMPLEX)
2537 || (flow2_completed && tablejump_p (BB_END (then_bb), NULL, NULL))))
2540 /* If the THEN block has no successors, conditional execution can still
2541 make a conditional call. Don't do this unless the ELSE block has
2542 only one incoming edge -- the CFG manipulation is too ugly otherwise.
2543 Check for the last insn of the THEN block being an indirect jump, which
2544 is listed as not having any successors, but confuses the rest of the CE
2545 code processing. ??? we should fix this in the future. */
2546 if (then_succ == NULL)
2548 if (else_bb->pred->pred_next == NULL_EDGE)
2550 rtx last_insn = BB_END (then_bb);
2553 && GET_CODE (last_insn) == NOTE
2554 && last_insn != BB_HEAD (then_bb))
2555 last_insn = PREV_INSN (last_insn);
2558 && GET_CODE (last_insn) == JUMP_INSN
2559 && ! simplejump_p (last_insn))
2563 else_bb = NULL_BLOCK;
2569 /* If the THEN block's successor is the other edge out of the TEST block,
2570 then we have an IF-THEN combo without an ELSE. */
2571 else if (then_succ->dest == else_bb)
2574 else_bb = NULL_BLOCK;
2577 /* If the THEN and ELSE block meet in a subsequent block, and the ELSE
2578 has exactly one predecessor and one successor, and the outgoing edge
2579 is not complex, then we have an IF-THEN-ELSE combo. */
2580 else if (else_succ != NULL_EDGE
2581 && then_succ->dest == else_succ->dest
2582 && else_bb->pred->pred_next == NULL_EDGE
2583 && else_succ->succ_next == NULL_EDGE
2584 && ! (else_succ->flags & EDGE_COMPLEX)
2585 && ! (flow2_completed && tablejump_p (BB_END (else_bb), NULL, NULL)))
2586 join_bb = else_succ->dest;
2588 /* Otherwise it is not an IF-THEN or IF-THEN-ELSE combination. */
2592 num_possible_if_blocks++;
2597 "\nIF-THEN%s block found, pass %d, start block %d "
2598 "[insn %d], then %d [%d]",
2599 (else_bb) ? "-ELSE" : "",
2602 BB_HEAD (test_bb) ? (int)INSN_UID (BB_HEAD (test_bb)) : -1,
2604 BB_HEAD (then_bb) ? (int)INSN_UID (BB_HEAD (then_bb)) : -1);
2607 fprintf (dump_file, ", else %d [%d]",
2609 BB_HEAD (else_bb) ? (int)INSN_UID (BB_HEAD (else_bb)) : -1);
2611 fprintf (dump_file, ", join %d [%d]",
2613 BB_HEAD (join_bb) ? (int)INSN_UID (BB_HEAD (join_bb)) : -1);
2615 if (ce_info->num_multiple_test_blocks > 0)
2616 fprintf (dump_file, ", %d %s block%s last test %d [%d]",
2617 ce_info->num_multiple_test_blocks,
2618 (ce_info->and_and_p) ? "&&" : "||",
2619 (ce_info->num_multiple_test_blocks == 1) ? "" : "s",
2620 ce_info->last_test_bb->index,
2621 ((BB_HEAD (ce_info->last_test_bb))
2622 ? (int)INSN_UID (BB_HEAD (ce_info->last_test_bb))
2625 fputc ('\n', dump_file);
2628 /* Make sure IF, THEN, and ELSE, blocks are adjacent. Actually, we get the
2629 first condition for free, since we've already asserted that there's a
2630 fallthru edge from IF to THEN. Likewise for the && and || blocks, since
2631 we checked the FALLTHRU flag, those are already adjacent to the last IF
2633 /* ??? As an enhancement, move the ELSE block. Have to deal with
2634 BLOCK notes, if by no other means than aborting the merge if they
2635 exist. Sticky enough I don't want to think about it now. */
2637 if (else_bb && (next = next->next_bb) != else_bb)
2639 if ((next = next->next_bb) != join_bb && join_bb != EXIT_BLOCK_PTR)
2647 /* Do the real work. */
2648 ce_info->else_bb = else_bb;
2649 ce_info->join_bb = join_bb;
2651 return process_if_block (ce_info);
2654 /* Convert a branch over a trap, or a branch
2655 to a trap, into a conditional trap. */
2658 find_cond_trap (basic_block test_bb, edge then_edge, edge else_edge)
2660 basic_block then_bb = then_edge->dest;
2661 basic_block else_bb = else_edge->dest;
2662 basic_block other_bb, trap_bb;
2663 rtx trap, jump, cond, cond_earliest, seq;
2666 /* Locate the block with the trap instruction. */
2667 /* ??? While we look for no successors, we really ought to allow
2668 EH successors. Need to fix merge_if_block for that to work. */
2669 if ((trap = block_has_only_trap (then_bb)) != NULL)
2670 trap_bb = then_bb, other_bb = else_bb;
2671 else if ((trap = block_has_only_trap (else_bb)) != NULL)
2672 trap_bb = else_bb, other_bb = then_bb;
2678 fprintf (dump_file, "\nTRAP-IF block found, start %d, trap %d\n",
2679 test_bb->index, trap_bb->index);
2682 /* If this is not a standard conditional jump, we can't parse it. */
2683 jump = BB_END (test_bb);
2684 cond = noce_get_condition (jump, &cond_earliest);
2688 /* If the conditional jump is more than just a conditional jump, then
2689 we can not do if-conversion on this block. */
2690 if (! onlyjump_p (jump))
2693 /* We must be comparing objects whose modes imply the size. */
2694 if (GET_MODE (XEXP (cond, 0)) == BLKmode)
2697 /* Reverse the comparison code, if necessary. */
2698 code = GET_CODE (cond);
2699 if (then_bb == trap_bb)
2701 code = reversed_comparison_code (cond, jump);
2702 if (code == UNKNOWN)
2706 /* Attempt to generate the conditional trap. */
2707 seq = gen_cond_trap (code, XEXP (cond, 0),
2709 TRAP_CODE (PATTERN (trap)));
2715 /* Emit the new insns before cond_earliest. */
2716 emit_insn_before_setloc (seq, cond_earliest, INSN_LOCATOR (trap));
2718 /* Delete the trap block if possible. */
2719 remove_edge (trap_bb == then_bb ? then_edge : else_edge);
2720 if (trap_bb->pred == NULL)
2721 delete_basic_block (trap_bb);
2723 /* If the non-trap block and the test are now adjacent, merge them.
2724 Otherwise we must insert a direct branch. */
2725 if (test_bb->next_bb == other_bb)
2727 struct ce_if_block new_ce_info;
2729 memset (&new_ce_info, '\0', sizeof (new_ce_info));
2730 new_ce_info.test_bb = test_bb;
2731 new_ce_info.then_bb = NULL;
2732 new_ce_info.else_bb = NULL;
2733 new_ce_info.join_bb = other_bb;
2734 merge_if_block (&new_ce_info);
2740 lab = JUMP_LABEL (jump);
2741 newjump = emit_jump_insn_after (gen_jump (lab), jump);
2742 LABEL_NUSES (lab) += 1;
2743 JUMP_LABEL (newjump) = lab;
2744 emit_barrier_after (newjump);
2752 /* Subroutine of find_cond_trap: if BB contains only a trap insn,
2756 block_has_only_trap (basic_block bb)
2760 /* We're not the exit block. */
2761 if (bb == EXIT_BLOCK_PTR)
2764 /* The block must have no successors. */
2768 /* The only instruction in the THEN block must be the trap. */
2769 trap = first_active_insn (bb);
2770 if (! (trap == BB_END (bb)
2771 && GET_CODE (PATTERN (trap)) == TRAP_IF
2772 && TRAP_CONDITION (PATTERN (trap)) == const_true_rtx))
2778 /* Look for IF-THEN-ELSE cases in which one of THEN or ELSE is
2779 transformable, but not necessarily the other. There need be no
2782 Return TRUE if we were successful at converting the block.
2784 Cases we'd like to look at:
2787 if (test) goto over; // x not live
2795 if (! test) goto label;
2798 if (test) goto E; // x not live
2812 (3) // This one's really only interesting for targets that can do
2813 // multiway branching, e.g. IA-64 BBB bundles. For other targets
2814 // it results in multiple branches on a cache line, which often
2815 // does not sit well with predictors.
2817 if (test1) goto E; // predicted not taken
2833 (A) Don't do (2) if the branch is predicted against the block we're
2834 eliminating. Do it anyway if we can eliminate a branch; this requires
2835 that the sole successor of the eliminated block postdominate the other
2838 (B) With CE, on (3) we can steal from both sides of the if, creating
2847 Again, this is most useful if J postdominates.
2849 (C) CE substitutes for helpful life information.
2851 (D) These heuristics need a lot of work. */
2853 /* Tests for case 1 above. */
2856 find_if_case_1 (basic_block test_bb, edge then_edge, edge else_edge)
2858 basic_block then_bb = then_edge->dest;
2859 basic_block else_bb = else_edge->dest, new_bb;
2860 edge then_succ = then_bb->succ;
2863 /* If we are partitioning hot/cold basic blocks, we don't want to
2864 mess up unconditional or indirect jumps that cross between hot
2865 and cold sections. */
2867 if (flag_reorder_blocks_and_partition
2868 && ((BB_END (then_bb)
2869 && find_reg_note (BB_END (then_bb), REG_CROSSING_JUMP, NULL_RTX))
2870 || (BB_END (else_bb)
2871 && find_reg_note (BB_END (else_bb), REG_CROSSING_JUMP,
2875 /* THEN has one successor. */
2876 if (!then_succ || then_succ->succ_next != NULL)
2879 /* THEN does not fall through, but is not strange either. */
2880 if (then_succ->flags & (EDGE_COMPLEX | EDGE_FALLTHRU))
2883 /* THEN has one predecessor. */
2884 if (then_bb->pred->pred_next != NULL)
2887 /* THEN must do something. */
2888 if (forwarder_block_p (then_bb))
2891 num_possible_if_blocks++;
2894 "\nIF-CASE-1 found, start %d, then %d\n",
2895 test_bb->index, then_bb->index);
2897 /* THEN is small. */
2898 if (count_bb_insns (then_bb) > BRANCH_COST)
2901 /* Registers set are dead, or are predicable. */
2902 if (! dead_or_predicable (test_bb, then_bb, else_bb,
2903 then_bb->succ->dest, 1))
2906 /* Conversion went ok, including moving the insns and fixing up the
2907 jump. Adjust the CFG to match. */
2909 bitmap_operation (test_bb->global_live_at_end,
2910 else_bb->global_live_at_start,
2911 then_bb->global_live_at_end, BITMAP_IOR);
2913 new_bb = redirect_edge_and_branch_force (FALLTHRU_EDGE (test_bb), else_bb);
2914 then_bb_index = then_bb->index;
2915 delete_basic_block (then_bb);
2917 /* Make rest of code believe that the newly created block is the THEN_BB
2918 block we removed. */
2921 new_bb->index = then_bb_index;
2922 BASIC_BLOCK (then_bb_index) = new_bb;
2924 /* We've possibly created jump to next insn, cleanup_cfg will solve that
2928 num_updated_if_blocks++;
2933 /* Test for case 2 above. */
2936 find_if_case_2 (basic_block test_bb, edge then_edge, edge else_edge)
2938 basic_block then_bb = then_edge->dest;
2939 basic_block else_bb = else_edge->dest;
2940 edge else_succ = else_bb->succ;
2943 /* If we are partitioning hot/cold basic blocks, we don't want to
2944 mess up unconditional or indirect jumps that cross between hot
2945 and cold sections. */
2947 if (flag_reorder_blocks_and_partition
2948 && ((BB_END (then_bb)
2949 && find_reg_note (BB_END (then_bb), REG_CROSSING_JUMP, NULL_RTX))
2950 || (BB_END (else_bb)
2951 && find_reg_note (BB_END (else_bb), REG_CROSSING_JUMP,
2955 /* ELSE has one successor. */
2956 if (!else_succ || else_succ->succ_next != NULL)
2959 /* ELSE outgoing edge is not complex. */
2960 if (else_succ->flags & EDGE_COMPLEX)
2963 /* ELSE has one predecessor. */
2964 if (else_bb->pred->pred_next != NULL)
2967 /* THEN is not EXIT. */
2968 if (then_bb->index < 0)
2971 /* ELSE is predicted or SUCC(ELSE) postdominates THEN. */
2972 note = find_reg_note (BB_END (test_bb), REG_BR_PROB, NULL_RTX);
2973 if (note && INTVAL (XEXP (note, 0)) >= REG_BR_PROB_BASE / 2)
2975 else if (else_succ->dest->index < 0
2976 || dominated_by_p (CDI_POST_DOMINATORS, then_bb,
2982 num_possible_if_blocks++;
2985 "\nIF-CASE-2 found, start %d, else %d\n",
2986 test_bb->index, else_bb->index);
2988 /* ELSE is small. */
2989 if (count_bb_insns (else_bb) > BRANCH_COST)
2992 /* Registers set are dead, or are predicable. */
2993 if (! dead_or_predicable (test_bb, else_bb, then_bb, else_succ->dest, 0))
2996 /* Conversion went ok, including moving the insns and fixing up the
2997 jump. Adjust the CFG to match. */
2999 bitmap_operation (test_bb->global_live_at_end,
3000 then_bb->global_live_at_start,
3001 else_bb->global_live_at_end, BITMAP_IOR);
3003 delete_basic_block (else_bb);
3006 num_updated_if_blocks++;
3008 /* ??? We may now fallthru from one of THEN's successors into a join
3009 block. Rerun cleanup_cfg? Examine things manually? Wait? */
3014 /* A subroutine of dead_or_predicable called through for_each_rtx.
3015 Return 1 if a memory is found. */
3018 find_memory (rtx *px, void *data ATTRIBUTE_UNUSED)
3020 return GET_CODE (*px) == MEM;
3023 /* Used by the code above to perform the actual rtl transformations.
3024 Return TRUE if successful.
3026 TEST_BB is the block containing the conditional branch. MERGE_BB
3027 is the block containing the code to manipulate. NEW_DEST is the
3028 label TEST_BB should be branching to after the conversion.
3029 REVERSEP is true if the sense of the branch should be reversed. */
3032 dead_or_predicable (basic_block test_bb, basic_block merge_bb,
3033 basic_block other_bb, basic_block new_dest, int reversep)
3035 rtx head, end, jump, earliest = NULL_RTX, old_dest, new_label = NULL_RTX;
3037 jump = BB_END (test_bb);
3039 /* Find the extent of the real code in the merge block. */
3040 head = BB_HEAD (merge_bb);
3041 end = BB_END (merge_bb);
3043 if (GET_CODE (head) == CODE_LABEL)
3044 head = NEXT_INSN (head);
3045 if (GET_CODE (head) == NOTE)
3049 head = end = NULL_RTX;
3052 head = NEXT_INSN (head);
3055 if (GET_CODE (end) == JUMP_INSN)
3059 head = end = NULL_RTX;
3062 end = PREV_INSN (end);
3065 /* Disable handling dead code by conditional execution if the machine needs
3066 to do anything funny with the tests, etc. */
3067 #ifndef IFCVT_MODIFY_TESTS
3068 if (HAVE_conditional_execution)
3070 /* In the conditional execution case, we have things easy. We know
3071 the condition is reversible. We don't have to check life info
3072 because we're going to conditionally execute the code anyway.
3073 All that's left is making sure the insns involved can actually
3078 cond = cond_exec_get_condition (jump);
3082 prob_val = find_reg_note (jump, REG_BR_PROB, NULL_RTX);
3084 prob_val = XEXP (prob_val, 0);
3088 enum rtx_code rev = reversed_comparison_code (cond, jump);
3091 cond = gen_rtx_fmt_ee (rev, GET_MODE (cond), XEXP (cond, 0),
3094 prob_val = GEN_INT (REG_BR_PROB_BASE - INTVAL (prob_val));
3097 if (! cond_exec_process_insns ((ce_if_block_t *)0, head, end, cond,
3106 /* In the non-conditional execution case, we have to verify that there
3107 are no trapping operations, no calls, no references to memory, and
3108 that any registers modified are dead at the branch site. */
3110 rtx insn, cond, prev;
3111 regset_head merge_set_head, tmp_head, test_live_head, test_set_head;
3112 regset merge_set, tmp, test_live, test_set;
3113 struct propagate_block_info *pbi;
3116 /* Check for no calls or trapping operations. */
3117 for (insn = head; ; insn = NEXT_INSN (insn))
3119 if (GET_CODE (insn) == CALL_INSN)
3123 if (may_trap_p (PATTERN (insn)))
3126 /* ??? Even non-trapping memories such as stack frame
3127 references must be avoided. For stores, we collect
3128 no lifetime info; for reads, we'd have to assert
3129 true_dependence false against every store in the
3131 if (for_each_rtx (&PATTERN (insn), find_memory, NULL))
3138 if (! any_condjump_p (jump))
3141 /* Find the extent of the conditional. */
3142 cond = noce_get_condition (jump, &earliest);
3147 MERGE_SET = set of registers set in MERGE_BB
3148 TEST_LIVE = set of registers live at EARLIEST
3149 TEST_SET = set of registers set between EARLIEST and the
3150 end of the block. */
3152 tmp = INITIALIZE_REG_SET (tmp_head);
3153 merge_set = INITIALIZE_REG_SET (merge_set_head);
3154 test_live = INITIALIZE_REG_SET (test_live_head);
3155 test_set = INITIALIZE_REG_SET (test_set_head);
3157 /* ??? bb->local_set is only valid during calculate_global_regs_live,
3158 so we must recompute usage for MERGE_BB. Not so bad, I suppose,
3159 since we've already asserted that MERGE_BB is small. */
3160 propagate_block (merge_bb, tmp, merge_set, merge_set, 0);
3162 /* For small register class machines, don't lengthen lifetimes of
3163 hard registers before reload. */
3164 if (SMALL_REGISTER_CLASSES && ! reload_completed)
3166 EXECUTE_IF_SET_IN_BITMAP
3169 if (i < FIRST_PSEUDO_REGISTER
3171 && ! global_regs[i])
3176 /* For TEST, we're interested in a range of insns, not a whole block.
3177 Moreover, we're interested in the insns live from OTHER_BB. */
3179 COPY_REG_SET (test_live, other_bb->global_live_at_start);
3180 pbi = init_propagate_block_info (test_bb, test_live, test_set, test_set,
3183 for (insn = jump; ; insn = prev)
3185 prev = propagate_one_insn (pbi, insn);
3186 if (insn == earliest)
3190 free_propagate_block_info (pbi);
3192 /* We can perform the transformation if
3193 MERGE_SET & (TEST_SET | TEST_LIVE)
3195 TEST_SET & merge_bb->global_live_at_start
3198 bitmap_operation (tmp, test_set, test_live, BITMAP_IOR);
3199 bitmap_operation (tmp, tmp, merge_set, BITMAP_AND);
3200 EXECUTE_IF_SET_IN_BITMAP(tmp, 0, i, fail = 1);
3202 bitmap_operation (tmp, test_set, merge_bb->global_live_at_start,
3204 EXECUTE_IF_SET_IN_BITMAP(tmp, 0, i, fail = 1);
3207 FREE_REG_SET (merge_set);
3208 FREE_REG_SET (test_live);
3209 FREE_REG_SET (test_set);
3216 /* We don't want to use normal invert_jump or redirect_jump because
3217 we don't want to delete_insn called. Also, we want to do our own
3218 change group management. */
3220 old_dest = JUMP_LABEL (jump);
3221 if (other_bb != new_dest)
3223 new_label = block_label (new_dest);
3225 ? ! invert_jump_1 (jump, new_label)
3226 : ! redirect_jump_1 (jump, new_label))
3230 if (! apply_change_group ())
3233 if (other_bb != new_dest)
3236 LABEL_NUSES (old_dest) -= 1;
3238 LABEL_NUSES (new_label) += 1;
3239 JUMP_LABEL (jump) = new_label;
3241 invert_br_probabilities (jump);
3243 redirect_edge_succ (BRANCH_EDGE (test_bb), new_dest);
3246 gcov_type count, probability;
3247 count = BRANCH_EDGE (test_bb)->count;
3248 BRANCH_EDGE (test_bb)->count = FALLTHRU_EDGE (test_bb)->count;
3249 FALLTHRU_EDGE (test_bb)->count = count;
3250 probability = BRANCH_EDGE (test_bb)->probability;
3251 BRANCH_EDGE (test_bb)->probability
3252 = FALLTHRU_EDGE (test_bb)->probability;
3253 FALLTHRU_EDGE (test_bb)->probability = probability;
3254 update_br_prob_note (test_bb);
3258 /* Move the insns out of MERGE_BB to before the branch. */
3261 if (end == BB_END (merge_bb))
3262 BB_END (merge_bb) = PREV_INSN (head);
3264 if (squeeze_notes (&head, &end))
3267 reorder_insns (head, end, PREV_INSN (earliest));
3270 /* Remove the jump and edge if we can. */
3271 if (other_bb == new_dest)
3274 remove_edge (BRANCH_EDGE (test_bb));
3275 /* ??? Can't merge blocks here, as then_bb is still in use.
3276 At minimum, the merge will get done just before bb-reorder. */
3286 /* Main entry point for all if-conversion. */
3289 if_convert (int x_life_data_ok)
3294 num_possible_if_blocks = 0;
3295 num_updated_if_blocks = 0;
3296 num_true_changes = 0;
3297 life_data_ok = (x_life_data_ok != 0);
3299 if ((! targetm.cannot_modify_jumps_p ())
3300 && (!flag_reorder_blocks_and_partition || !no_new_pseudos))
3301 mark_loop_exit_edges ();
3303 /* Compute postdominators if we think we'll use them. */
3304 if (HAVE_conditional_execution || life_data_ok)
3305 calculate_dominance_info (CDI_POST_DOMINATORS);
3310 /* Go through each of the basic blocks looking for things to convert. If we
3311 have conditional execution, we make multiple passes to allow us to handle
3312 IF-THEN{-ELSE} blocks within other IF-THEN{-ELSE} blocks. */
3316 cond_exec_changed_p = FALSE;
3319 #ifdef IFCVT_MULTIPLE_DUMPS
3320 if (dump_file && pass > 1)
3321 fprintf (dump_file, "\n\n========== Pass %d ==========\n", pass);
3327 while ((new_bb = find_if_header (bb, pass)))
3331 #ifdef IFCVT_MULTIPLE_DUMPS
3332 if (dump_file && cond_exec_changed_p)
3333 print_rtl_with_bb (dump_file, get_insns ());
3336 while (cond_exec_changed_p);
3338 #ifdef IFCVT_MULTIPLE_DUMPS
3340 fprintf (dump_file, "\n\n========== no more changes\n");
3343 free_dominance_info (CDI_POST_DOMINATORS);
3348 clear_aux_for_blocks ();
3350 /* Rebuild life info for basic blocks that require it. */
3351 if (num_true_changes && life_data_ok)
3353 /* If we allocated new pseudos, we must resize the array for sched1. */
3354 if (max_regno < max_reg_num ())
3356 max_regno = max_reg_num ();
3357 allocate_reg_info (max_regno, FALSE, FALSE);
3359 update_life_info_in_dirty_blocks (UPDATE_LIFE_GLOBAL_RM_NOTES,
3360 PROP_DEATH_NOTES | PROP_SCAN_DEAD_CODE
3361 | PROP_KILL_DEAD_CODE);
3364 /* Write the final stats. */
3365 if (dump_file && num_possible_if_blocks > 0)
3368 "\n%d possible IF blocks searched.\n",
3369 num_possible_if_blocks);
3371 "%d IF blocks converted.\n",
3372 num_updated_if_blocks);
3374 "%d true changes made.\n\n\n",
3378 #ifdef ENABLE_CHECKING
3379 verify_flow_info ();