1 /* If-conversion support.
2 Copyright (C) 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007
3 Free Software Foundation, Inc.
5 This file is part of GCC.
7 GCC is free software; you can redistribute it and/or modify it
8 under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 3, or (at your option)
12 GCC is distributed in the hope that it will be useful, but WITHOUT
13 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
14 or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public
15 License for more details.
17 You should have received a copy of the GNU General Public License
18 along with GCC; see the file COPYING3. If not see
19 <http://www.gnu.org/licenses/>. */
23 #include "coretypes.h"
30 #include "insn-config.h"
33 #include "hard-reg-set.h"
34 #include "basic-block.h"
44 #include "tree-pass.h"
50 #ifndef HAVE_conditional_execution
51 #define HAVE_conditional_execution 0
53 #ifndef HAVE_conditional_move
54 #define HAVE_conditional_move 0
65 #ifndef HAVE_conditional_trap
66 #define HAVE_conditional_trap 0
69 #ifndef MAX_CONDITIONAL_EXECUTE
70 #define MAX_CONDITIONAL_EXECUTE (BRANCH_COST + 1)
73 #define IFCVT_MULTIPLE_DUMPS 1
75 #define NULL_BLOCK ((basic_block) NULL)
77 /* # of IF-THEN or IF-THEN-ELSE blocks we looked at */
78 static int num_possible_if_blocks;
80 /* # of IF-THEN or IF-THEN-ELSE blocks were converted to conditional
82 static int num_updated_if_blocks;
84 /* # of changes made. */
85 static int num_true_changes;
87 /* Whether conditional execution changes were made. */
88 static int cond_exec_changed_p;
90 /* Forward references. */
91 static int count_bb_insns (const_basic_block);
92 static bool cheap_bb_rtx_cost_p (const_basic_block, int);
93 static rtx first_active_insn (basic_block);
94 static rtx last_active_insn (basic_block, int);
95 static basic_block block_fallthru (basic_block);
96 static int cond_exec_process_insns (ce_if_block_t *, rtx, rtx, rtx, rtx, int);
97 static rtx cond_exec_get_condition (rtx);
98 static rtx noce_get_condition (rtx, rtx *, bool);
99 static int noce_operand_ok (const_rtx);
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 noce_find_if_block (basic_block, edge, edge, int);
105 static int cond_exec_find_if_block (ce_if_block_t *);
106 static int find_if_case_1 (basic_block, edge, edge);
107 static int find_if_case_2 (basic_block, edge, edge);
108 static int find_memory (rtx *, void *);
109 static int dead_or_predicable (basic_block, basic_block, basic_block,
111 static void noce_emit_move_insn (rtx, rtx);
112 static rtx block_has_only_trap (basic_block);
114 /* Count the number of non-jump active insns in BB. */
117 count_bb_insns (const_basic_block bb)
120 rtx insn = BB_HEAD (bb);
124 if (CALL_P (insn) || NONJUMP_INSN_P (insn))
127 if (insn == BB_END (bb))
129 insn = NEXT_INSN (insn);
135 /* Determine whether the total insn_rtx_cost on non-jump insns in
136 basic block BB is less than MAX_COST. This function returns
137 false if the cost of any instruction could not be estimated. */
140 cheap_bb_rtx_cost_p (const_basic_block bb, int max_cost)
143 rtx insn = BB_HEAD (bb);
147 if (NONJUMP_INSN_P (insn))
149 int cost = insn_rtx_cost (PATTERN (insn));
153 /* If this instruction is the load or set of a "stack" register,
154 such as a floating point register on x87, then the cost of
155 speculatively executing this insn may need to include
156 the additional cost of popping its result off of the
157 register stack. Unfortunately, correctly recognizing and
158 accounting for this additional overhead is tricky, so for
159 now we simply prohibit such speculative execution. */
162 rtx set = single_set (insn);
163 if (set && STACK_REG_P (SET_DEST (set)))
169 if (count >= max_cost)
172 else if (CALL_P (insn))
175 if (insn == BB_END (bb))
177 insn = NEXT_INSN (insn);
183 /* Return the first non-jump active insn in the basic block. */
186 first_active_insn (basic_block bb)
188 rtx insn = BB_HEAD (bb);
192 if (insn == BB_END (bb))
194 insn = NEXT_INSN (insn);
197 while (NOTE_P (insn))
199 if (insn == BB_END (bb))
201 insn = NEXT_INSN (insn);
210 /* Return the last non-jump active (non-jump) insn in the basic block. */
213 last_active_insn (basic_block bb, int skip_use_p)
215 rtx insn = BB_END (bb);
216 rtx head = BB_HEAD (bb);
221 && NONJUMP_INSN_P (insn)
222 && GET_CODE (PATTERN (insn)) == USE))
226 insn = PREV_INSN (insn);
235 /* Return the basic block reached by falling though the basic block BB. */
238 block_fallthru (basic_block bb)
243 FOR_EACH_EDGE (e, ei, bb->succs)
244 if (e->flags & EDGE_FALLTHRU)
247 return (e) ? e->dest : NULL_BLOCK;
250 /* Go through a bunch of insns, converting them to conditional
251 execution format if possible. Return TRUE if all of the non-note
252 insns were processed. */
255 cond_exec_process_insns (ce_if_block_t *ce_info ATTRIBUTE_UNUSED,
256 /* if block information */rtx start,
257 /* first insn to look at */rtx end,
258 /* last insn to look at */rtx test,
259 /* conditional execution test */rtx prob_val,
260 /* probability of branch taken. */int mod_ok)
262 int must_be_last = FALSE;
270 for (insn = start; ; insn = NEXT_INSN (insn))
275 gcc_assert(NONJUMP_INSN_P (insn) || CALL_P (insn));
277 /* Remove USE insns that get in the way. */
278 if (reload_completed && GET_CODE (PATTERN (insn)) == USE)
280 /* ??? Ug. Actually unlinking the thing is problematic,
281 given what we'd have to coordinate with our callers. */
282 SET_INSN_DELETED (insn);
286 /* Last insn wasn't last? */
290 if (modified_in_p (test, insn))
297 /* Now build the conditional form of the instruction. */
298 pattern = PATTERN (insn);
299 xtest = copy_rtx (test);
301 /* If this is already a COND_EXEC, rewrite the test to be an AND of the
303 if (GET_CODE (pattern) == COND_EXEC)
305 if (GET_MODE (xtest) != GET_MODE (COND_EXEC_TEST (pattern)))
308 xtest = gen_rtx_AND (GET_MODE (xtest), xtest,
309 COND_EXEC_TEST (pattern));
310 pattern = COND_EXEC_CODE (pattern);
313 pattern = gen_rtx_COND_EXEC (VOIDmode, xtest, pattern);
315 /* If the machine needs to modify the insn being conditionally executed,
316 say for example to force a constant integer operand into a temp
317 register, do so here. */
318 #ifdef IFCVT_MODIFY_INSN
319 IFCVT_MODIFY_INSN (ce_info, pattern, insn);
324 validate_change (insn, &PATTERN (insn), pattern, 1);
326 if (CALL_P (insn) && prob_val)
327 validate_change (insn, ®_NOTES (insn),
328 alloc_EXPR_LIST (REG_BR_PROB, prob_val,
329 REG_NOTES (insn)), 1);
339 /* Return the condition for a jump. Do not do any special processing. */
342 cond_exec_get_condition (rtx jump)
346 if (any_condjump_p (jump))
347 test_if = SET_SRC (pc_set (jump));
350 cond = XEXP (test_if, 0);
352 /* If this branches to JUMP_LABEL when the condition is false,
353 reverse the condition. */
354 if (GET_CODE (XEXP (test_if, 2)) == LABEL_REF
355 && XEXP (XEXP (test_if, 2), 0) == JUMP_LABEL (jump))
357 enum rtx_code rev = reversed_comparison_code (cond, jump);
361 cond = gen_rtx_fmt_ee (rev, GET_MODE (cond), XEXP (cond, 0),
368 /* Given a simple IF-THEN or IF-THEN-ELSE block, attempt to convert it
369 to conditional execution. Return TRUE if we were successful at
370 converting the block. */
373 cond_exec_process_if_block (ce_if_block_t * ce_info,
374 /* if block information */int do_multiple_p)
376 basic_block test_bb = ce_info->test_bb; /* last test block */
377 basic_block then_bb = ce_info->then_bb; /* THEN */
378 basic_block else_bb = ce_info->else_bb; /* ELSE or NULL */
379 rtx test_expr; /* expression in IF_THEN_ELSE that is tested */
380 rtx then_start; /* first insn in THEN block */
381 rtx then_end; /* last insn + 1 in THEN block */
382 rtx else_start = NULL_RTX; /* first insn in ELSE block or NULL */
383 rtx else_end = NULL_RTX; /* last insn + 1 in ELSE block */
384 int max; /* max # of insns to convert. */
385 int then_mod_ok; /* whether conditional mods are ok in THEN */
386 rtx true_expr; /* test for else block insns */
387 rtx false_expr; /* test for then block insns */
388 rtx true_prob_val; /* probability of else block */
389 rtx false_prob_val; /* probability of then block */
391 enum rtx_code false_code;
393 /* If test is comprised of && or || elements, and we've failed at handling
394 all of them together, just use the last test if it is the special case of
395 && elements without an ELSE block. */
396 if (!do_multiple_p && ce_info->num_multiple_test_blocks)
398 if (else_bb || ! ce_info->and_and_p)
401 ce_info->test_bb = test_bb = ce_info->last_test_bb;
402 ce_info->num_multiple_test_blocks = 0;
403 ce_info->num_and_and_blocks = 0;
404 ce_info->num_or_or_blocks = 0;
407 /* Find the conditional jump to the ELSE or JOIN part, and isolate
409 test_expr = cond_exec_get_condition (BB_END (test_bb));
413 /* If the conditional jump is more than just a conditional jump,
414 then we can not do conditional execution conversion on this block. */
415 if (! onlyjump_p (BB_END (test_bb)))
418 /* Collect the bounds of where we're to search, skipping any labels, jumps
419 and notes at the beginning and end of the block. Then count the total
420 number of insns and see if it is small enough to convert. */
421 then_start = first_active_insn (then_bb);
422 then_end = last_active_insn (then_bb, TRUE);
423 n_insns = ce_info->num_then_insns = count_bb_insns (then_bb);
424 max = MAX_CONDITIONAL_EXECUTE;
429 else_start = first_active_insn (else_bb);
430 else_end = last_active_insn (else_bb, TRUE);
431 n_insns += ce_info->num_else_insns = count_bb_insns (else_bb);
437 /* Map test_expr/test_jump into the appropriate MD tests to use on
438 the conditionally executed code. */
440 true_expr = test_expr;
442 false_code = reversed_comparison_code (true_expr, BB_END (test_bb));
443 if (false_code != UNKNOWN)
444 false_expr = gen_rtx_fmt_ee (false_code, GET_MODE (true_expr),
445 XEXP (true_expr, 0), XEXP (true_expr, 1));
447 false_expr = NULL_RTX;
449 #ifdef IFCVT_MODIFY_TESTS
450 /* If the machine description needs to modify the tests, such as setting a
451 conditional execution register from a comparison, it can do so here. */
452 IFCVT_MODIFY_TESTS (ce_info, true_expr, false_expr);
454 /* See if the conversion failed. */
455 if (!true_expr || !false_expr)
459 true_prob_val = find_reg_note (BB_END (test_bb), REG_BR_PROB, NULL_RTX);
462 true_prob_val = XEXP (true_prob_val, 0);
463 false_prob_val = GEN_INT (REG_BR_PROB_BASE - INTVAL (true_prob_val));
466 false_prob_val = NULL_RTX;
468 /* If we have && or || tests, do them here. These tests are in the adjacent
469 blocks after the first block containing the test. */
470 if (ce_info->num_multiple_test_blocks > 0)
472 basic_block bb = test_bb;
473 basic_block last_test_bb = ce_info->last_test_bb;
482 enum rtx_code f_code;
484 bb = block_fallthru (bb);
485 start = first_active_insn (bb);
486 end = last_active_insn (bb, TRUE);
488 && ! cond_exec_process_insns (ce_info, start, end, false_expr,
489 false_prob_val, FALSE))
492 /* If the conditional jump is more than just a conditional jump, then
493 we can not do conditional execution conversion on this block. */
494 if (! onlyjump_p (BB_END (bb)))
497 /* Find the conditional jump and isolate the test. */
498 t = cond_exec_get_condition (BB_END (bb));
502 f_code = reversed_comparison_code (t, BB_END (bb));
503 if (f_code == UNKNOWN)
506 f = gen_rtx_fmt_ee (f_code, GET_MODE (t), XEXP (t, 0), XEXP (t, 1));
507 if (ce_info->and_and_p)
509 t = gen_rtx_AND (GET_MODE (t), true_expr, t);
510 f = gen_rtx_IOR (GET_MODE (t), false_expr, f);
514 t = gen_rtx_IOR (GET_MODE (t), true_expr, t);
515 f = gen_rtx_AND (GET_MODE (t), false_expr, f);
518 /* If the machine description needs to modify the tests, such as
519 setting a conditional execution register from a comparison, it can
521 #ifdef IFCVT_MODIFY_MULTIPLE_TESTS
522 IFCVT_MODIFY_MULTIPLE_TESTS (ce_info, bb, t, f);
524 /* See if the conversion failed. */
532 while (bb != last_test_bb);
535 /* For IF-THEN-ELSE blocks, we don't allow modifications of the test
536 on then THEN block. */
537 then_mod_ok = (else_bb == NULL_BLOCK);
539 /* Go through the THEN and ELSE blocks converting the insns if possible
540 to conditional execution. */
544 || ! cond_exec_process_insns (ce_info, then_start, then_end,
545 false_expr, false_prob_val,
549 if (else_bb && else_end
550 && ! cond_exec_process_insns (ce_info, else_start, else_end,
551 true_expr, true_prob_val, TRUE))
554 /* If we cannot apply the changes, fail. Do not go through the normal fail
555 processing, since apply_change_group will call cancel_changes. */
556 if (! apply_change_group ())
558 #ifdef IFCVT_MODIFY_CANCEL
559 /* Cancel any machine dependent changes. */
560 IFCVT_MODIFY_CANCEL (ce_info);
565 #ifdef IFCVT_MODIFY_FINAL
566 /* Do any machine dependent final modifications. */
567 IFCVT_MODIFY_FINAL (ce_info);
570 /* Conversion succeeded. */
572 fprintf (dump_file, "%d insn%s converted to conditional execution.\n",
573 n_insns, (n_insns == 1) ? " was" : "s were");
575 /* Merge the blocks! */
576 merge_if_block (ce_info);
577 cond_exec_changed_p = TRUE;
581 #ifdef IFCVT_MODIFY_CANCEL
582 /* Cancel any machine dependent changes. */
583 IFCVT_MODIFY_CANCEL (ce_info);
590 /* Used by noce_process_if_block to communicate with its subroutines.
592 The subroutines know that A and B may be evaluated freely. They
593 know that X is a register. They should insert new instructions
594 before cond_earliest. */
598 /* The basic blocks that make up the IF-THEN-{ELSE-,}JOIN block. */
599 basic_block test_bb, then_bb, else_bb, join_bb;
601 /* The jump that ends TEST_BB. */
604 /* The jump condition. */
607 /* New insns should be inserted before this one. */
610 /* Insns in the THEN and ELSE block. There is always just this
611 one insns in those blocks. The insns are single_set insns.
612 If there was no ELSE block, INSN_B is the last insn before
613 COND_EARLIEST, or NULL_RTX. In the former case, the insn
614 operands are still valid, as if INSN_B was moved down below
618 /* The SET_SRC of INSN_A and INSN_B. */
621 /* The SET_DEST of INSN_A. */
624 /* True if this if block is not canonical. In the canonical form of
625 if blocks, the THEN_BB is the block reached via the fallthru edge
626 from TEST_BB. For the noce transformations, we allow the symmetric
628 bool then_else_reversed;
631 static rtx noce_emit_store_flag (struct noce_if_info *, rtx, int, int);
632 static int noce_try_move (struct noce_if_info *);
633 static int noce_try_store_flag (struct noce_if_info *);
634 static int noce_try_addcc (struct noce_if_info *);
635 static int noce_try_store_flag_constants (struct noce_if_info *);
636 static int noce_try_store_flag_mask (struct noce_if_info *);
637 static rtx noce_emit_cmove (struct noce_if_info *, rtx, enum rtx_code, rtx,
639 static int noce_try_cmove (struct noce_if_info *);
640 static int noce_try_cmove_arith (struct noce_if_info *);
641 static rtx noce_get_alt_condition (struct noce_if_info *, rtx, rtx *);
642 static int noce_try_minmax (struct noce_if_info *);
643 static int noce_try_abs (struct noce_if_info *);
644 static int noce_try_sign_mask (struct noce_if_info *);
646 /* Helper function for noce_try_store_flag*. */
649 noce_emit_store_flag (struct noce_if_info *if_info, rtx x, int reversep,
652 rtx cond = if_info->cond;
656 cond_complex = (! general_operand (XEXP (cond, 0), VOIDmode)
657 || ! general_operand (XEXP (cond, 1), VOIDmode));
659 /* If earliest == jump, or when the condition is complex, try to
660 build the store_flag insn directly. */
663 cond = XEXP (SET_SRC (pc_set (if_info->jump)), 0);
666 code = reversed_comparison_code (cond, if_info->jump);
668 code = GET_CODE (cond);
670 if ((if_info->cond_earliest == if_info->jump || cond_complex)
671 && (normalize == 0 || STORE_FLAG_VALUE == normalize))
675 tmp = gen_rtx_fmt_ee (code, GET_MODE (x), XEXP (cond, 0),
677 tmp = gen_rtx_SET (VOIDmode, x, tmp);
680 tmp = emit_insn (tmp);
682 if (recog_memoized (tmp) >= 0)
688 if_info->cond_earliest = if_info->jump;
696 /* Don't even try if the comparison operands or the mode of X are weird. */
697 if (cond_complex || !SCALAR_INT_MODE_P (GET_MODE (x)))
700 return emit_store_flag (x, code, XEXP (cond, 0),
701 XEXP (cond, 1), VOIDmode,
702 (code == LTU || code == LEU
703 || code == GEU || code == GTU), normalize);
706 /* Emit instruction to move an rtx, possibly into STRICT_LOW_PART.
707 X is the destination/target and Y is the value to copy. */
710 noce_emit_move_insn (rtx x, rtx y)
712 enum machine_mode outmode;
716 if (GET_CODE (x) != STRICT_LOW_PART)
718 rtx seq, insn, target;
722 /* Check that the SET_SRC is reasonable before calling emit_move_insn,
723 otherwise construct a suitable SET pattern ourselves. */
724 insn = (OBJECT_P (y) || CONSTANT_P (y) || GET_CODE (y) == SUBREG)
725 ? emit_move_insn (x, y)
726 : emit_insn (gen_rtx_SET (VOIDmode, x, y));
730 if (recog_memoized (insn) <= 0)
732 if (GET_CODE (x) == ZERO_EXTRACT)
734 rtx op = XEXP (x, 0);
735 unsigned HOST_WIDE_INT size = INTVAL (XEXP (x, 1));
736 unsigned HOST_WIDE_INT start = INTVAL (XEXP (x, 2));
738 /* store_bit_field expects START to be relative to
739 BYTES_BIG_ENDIAN and adjusts this value for machines with
740 BITS_BIG_ENDIAN != BYTES_BIG_ENDIAN. In order to be able to
741 invoke store_bit_field again it is necessary to have the START
742 value from the first call. */
743 if (BITS_BIG_ENDIAN != BYTES_BIG_ENDIAN)
746 start = BITS_PER_UNIT - start - size;
749 gcc_assert (REG_P (op));
750 start = BITS_PER_WORD - start - size;
754 gcc_assert (start < (MEM_P (op) ? BITS_PER_UNIT : BITS_PER_WORD));
755 store_bit_field (op, size, start, GET_MODE (x), y);
759 switch (GET_RTX_CLASS (GET_CODE (y)))
762 ot = code_to_optab[GET_CODE (y)];
766 target = expand_unop (GET_MODE (y), ot, XEXP (y, 0), x, 0);
767 if (target != NULL_RTX)
770 emit_move_insn (x, target);
779 ot = code_to_optab[GET_CODE (y)];
783 target = expand_binop (GET_MODE (y), ot,
784 XEXP (y, 0), XEXP (y, 1),
786 if (target != NULL_RTX)
789 emit_move_insn (x, target);
806 inner = XEXP (outer, 0);
807 outmode = GET_MODE (outer);
808 bitpos = SUBREG_BYTE (outer) * BITS_PER_UNIT;
809 store_bit_field (inner, GET_MODE_BITSIZE (outmode), bitpos, outmode, y);
812 /* Return sequence of instructions generated by if conversion. This
813 function calls end_sequence() to end the current stream, ensures
814 that are instructions are unshared, recognizable non-jump insns.
815 On failure, this function returns a NULL_RTX. */
818 end_ifcvt_sequence (struct noce_if_info *if_info)
821 rtx seq = get_insns ();
823 set_used_flags (if_info->x);
824 set_used_flags (if_info->cond);
825 unshare_all_rtl_in_chain (seq);
828 /* Make sure that all of the instructions emitted are recognizable,
829 and that we haven't introduced a new jump instruction.
830 As an exercise for the reader, build a general mechanism that
831 allows proper placement of required clobbers. */
832 for (insn = seq; insn; insn = NEXT_INSN (insn))
834 || recog_memoized (insn) == -1)
840 /* Convert "if (a != b) x = a; else x = b" into "x = a" and
841 "if (a == b) x = a; else x = b" into "x = b". */
844 noce_try_move (struct noce_if_info *if_info)
846 rtx cond = if_info->cond;
847 enum rtx_code code = GET_CODE (cond);
850 if (code != NE && code != EQ)
853 /* This optimization isn't valid if either A or B could be a NaN
855 if (HONOR_NANS (GET_MODE (if_info->x))
856 || HONOR_SIGNED_ZEROS (GET_MODE (if_info->x)))
859 /* Check whether the operands of the comparison are A and in
861 if ((rtx_equal_p (if_info->a, XEXP (cond, 0))
862 && rtx_equal_p (if_info->b, XEXP (cond, 1)))
863 || (rtx_equal_p (if_info->a, XEXP (cond, 1))
864 && rtx_equal_p (if_info->b, XEXP (cond, 0))))
866 y = (code == EQ) ? if_info->a : if_info->b;
868 /* Avoid generating the move if the source is the destination. */
869 if (! rtx_equal_p (if_info->x, y))
872 noce_emit_move_insn (if_info->x, y);
873 seq = end_ifcvt_sequence (if_info);
877 emit_insn_before_setloc (seq, if_info->jump,
878 INSN_LOCATOR (if_info->insn_a));
885 /* Convert "if (test) x = 1; else x = 0".
887 Only try 0 and STORE_FLAG_VALUE here. Other combinations will be
888 tried in noce_try_store_flag_constants after noce_try_cmove has had
889 a go at the conversion. */
892 noce_try_store_flag (struct noce_if_info *if_info)
897 if (GET_CODE (if_info->b) == CONST_INT
898 && INTVAL (if_info->b) == STORE_FLAG_VALUE
899 && if_info->a == const0_rtx)
901 else if (if_info->b == const0_rtx
902 && GET_CODE (if_info->a) == CONST_INT
903 && INTVAL (if_info->a) == STORE_FLAG_VALUE
904 && (reversed_comparison_code (if_info->cond, if_info->jump)
912 target = noce_emit_store_flag (if_info, if_info->x, reversep, 0);
915 if (target != if_info->x)
916 noce_emit_move_insn (if_info->x, target);
918 seq = end_ifcvt_sequence (if_info);
922 emit_insn_before_setloc (seq, if_info->jump,
923 INSN_LOCATOR (if_info->insn_a));
933 /* Convert "if (test) x = a; else x = b", for A and B constant. */
936 noce_try_store_flag_constants (struct noce_if_info *if_info)
940 HOST_WIDE_INT itrue, ifalse, diff, tmp;
941 int normalize, can_reverse;
942 enum machine_mode mode;
944 if (GET_CODE (if_info->a) == CONST_INT
945 && GET_CODE (if_info->b) == CONST_INT)
947 mode = GET_MODE (if_info->x);
948 ifalse = INTVAL (if_info->a);
949 itrue = INTVAL (if_info->b);
951 /* Make sure we can represent the difference between the two values. */
952 if ((itrue - ifalse > 0)
953 != ((ifalse < 0) != (itrue < 0) ? ifalse < 0 : ifalse < itrue))
956 diff = trunc_int_for_mode (itrue - ifalse, mode);
958 can_reverse = (reversed_comparison_code (if_info->cond, if_info->jump)
962 if (diff == STORE_FLAG_VALUE || diff == -STORE_FLAG_VALUE)
964 else if (ifalse == 0 && exact_log2 (itrue) >= 0
965 && (STORE_FLAG_VALUE == 1
966 || BRANCH_COST >= 2))
968 else if (itrue == 0 && exact_log2 (ifalse) >= 0 && can_reverse
969 && (STORE_FLAG_VALUE == 1 || BRANCH_COST >= 2))
970 normalize = 1, reversep = 1;
972 && (STORE_FLAG_VALUE == -1
973 || BRANCH_COST >= 2))
975 else if (ifalse == -1 && can_reverse
976 && (STORE_FLAG_VALUE == -1 || BRANCH_COST >= 2))
977 normalize = -1, reversep = 1;
978 else if ((BRANCH_COST >= 2 && STORE_FLAG_VALUE == -1)
986 tmp = itrue; itrue = ifalse; ifalse = tmp;
987 diff = trunc_int_for_mode (-diff, mode);
991 target = noce_emit_store_flag (if_info, if_info->x, reversep, normalize);
998 /* if (test) x = 3; else x = 4;
999 => x = 3 + (test == 0); */
1000 if (diff == STORE_FLAG_VALUE || diff == -STORE_FLAG_VALUE)
1002 target = expand_simple_binop (mode,
1003 (diff == STORE_FLAG_VALUE
1005 GEN_INT (ifalse), target, if_info->x, 0,
1009 /* if (test) x = 8; else x = 0;
1010 => x = (test != 0) << 3; */
1011 else if (ifalse == 0 && (tmp = exact_log2 (itrue)) >= 0)
1013 target = expand_simple_binop (mode, ASHIFT,
1014 target, GEN_INT (tmp), if_info->x, 0,
1018 /* if (test) x = -1; else x = b;
1019 => x = -(test != 0) | b; */
1020 else if (itrue == -1)
1022 target = expand_simple_binop (mode, IOR,
1023 target, GEN_INT (ifalse), if_info->x, 0,
1027 /* if (test) x = a; else x = b;
1028 => x = (-(test != 0) & (b - a)) + a; */
1031 target = expand_simple_binop (mode, AND,
1032 target, GEN_INT (diff), if_info->x, 0,
1035 target = expand_simple_binop (mode, PLUS,
1036 target, GEN_INT (ifalse),
1037 if_info->x, 0, OPTAB_WIDEN);
1046 if (target != if_info->x)
1047 noce_emit_move_insn (if_info->x, target);
1049 seq = end_ifcvt_sequence (if_info);
1053 emit_insn_before_setloc (seq, if_info->jump,
1054 INSN_LOCATOR (if_info->insn_a));
1061 /* Convert "if (test) foo++" into "foo += (test != 0)", and
1062 similarly for "foo--". */
1065 noce_try_addcc (struct noce_if_info *if_info)
1068 int subtract, normalize;
1070 if (GET_CODE (if_info->a) == PLUS
1071 && rtx_equal_p (XEXP (if_info->a, 0), if_info->b)
1072 && (reversed_comparison_code (if_info->cond, if_info->jump)
1075 rtx cond = if_info->cond;
1076 enum rtx_code code = reversed_comparison_code (cond, if_info->jump);
1078 /* First try to use addcc pattern. */
1079 if (general_operand (XEXP (cond, 0), VOIDmode)
1080 && general_operand (XEXP (cond, 1), VOIDmode))
1083 target = emit_conditional_add (if_info->x, code,
1088 XEXP (if_info->a, 1),
1089 GET_MODE (if_info->x),
1090 (code == LTU || code == GEU
1091 || code == LEU || code == GTU));
1094 if (target != if_info->x)
1095 noce_emit_move_insn (if_info->x, target);
1097 seq = end_ifcvt_sequence (if_info);
1101 emit_insn_before_setloc (seq, if_info->jump,
1102 INSN_LOCATOR (if_info->insn_a));
1108 /* If that fails, construct conditional increment or decrement using
1110 if (BRANCH_COST >= 2
1111 && (XEXP (if_info->a, 1) == const1_rtx
1112 || XEXP (if_info->a, 1) == constm1_rtx))
1115 if (STORE_FLAG_VALUE == INTVAL (XEXP (if_info->a, 1)))
1116 subtract = 0, normalize = 0;
1117 else if (-STORE_FLAG_VALUE == INTVAL (XEXP (if_info->a, 1)))
1118 subtract = 1, normalize = 0;
1120 subtract = 0, normalize = INTVAL (XEXP (if_info->a, 1));
1123 target = noce_emit_store_flag (if_info,
1124 gen_reg_rtx (GET_MODE (if_info->x)),
1128 target = expand_simple_binop (GET_MODE (if_info->x),
1129 subtract ? MINUS : PLUS,
1130 if_info->b, target, if_info->x,
1134 if (target != if_info->x)
1135 noce_emit_move_insn (if_info->x, target);
1137 seq = end_ifcvt_sequence (if_info);
1141 emit_insn_before_setloc (seq, if_info->jump,
1142 INSN_LOCATOR (if_info->insn_a));
1152 /* Convert "if (test) x = 0;" to "x &= -(test == 0);" */
1155 noce_try_store_flag_mask (struct noce_if_info *if_info)
1161 if ((BRANCH_COST >= 2
1162 || STORE_FLAG_VALUE == -1)
1163 && ((if_info->a == const0_rtx
1164 && rtx_equal_p (if_info->b, if_info->x))
1165 || ((reversep = (reversed_comparison_code (if_info->cond,
1168 && if_info->b == const0_rtx
1169 && rtx_equal_p (if_info->a, if_info->x))))
1172 target = noce_emit_store_flag (if_info,
1173 gen_reg_rtx (GET_MODE (if_info->x)),
1176 target = expand_simple_binop (GET_MODE (if_info->x), AND,
1178 target, if_info->x, 0,
1183 if (target != if_info->x)
1184 noce_emit_move_insn (if_info->x, target);
1186 seq = end_ifcvt_sequence (if_info);
1190 emit_insn_before_setloc (seq, if_info->jump,
1191 INSN_LOCATOR (if_info->insn_a));
1201 /* Helper function for noce_try_cmove and noce_try_cmove_arith. */
1204 noce_emit_cmove (struct noce_if_info *if_info, rtx x, enum rtx_code code,
1205 rtx cmp_a, rtx cmp_b, rtx vfalse, rtx vtrue)
1207 /* If earliest == jump, try to build the cmove insn directly.
1208 This is helpful when combine has created some complex condition
1209 (like for alpha's cmovlbs) that we can't hope to regenerate
1210 through the normal interface. */
1212 if (if_info->cond_earliest == if_info->jump)
1216 tmp = gen_rtx_fmt_ee (code, GET_MODE (if_info->cond), cmp_a, cmp_b);
1217 tmp = gen_rtx_IF_THEN_ELSE (GET_MODE (x), tmp, vtrue, vfalse);
1218 tmp = gen_rtx_SET (VOIDmode, x, tmp);
1221 tmp = emit_insn (tmp);
1223 if (recog_memoized (tmp) >= 0)
1235 /* Don't even try if the comparison operands are weird. */
1236 if (! general_operand (cmp_a, GET_MODE (cmp_a))
1237 || ! general_operand (cmp_b, GET_MODE (cmp_b)))
1240 #if HAVE_conditional_move
1241 return emit_conditional_move (x, code, cmp_a, cmp_b, VOIDmode,
1242 vtrue, vfalse, GET_MODE (x),
1243 (code == LTU || code == GEU
1244 || code == LEU || code == GTU));
1246 /* We'll never get here, as noce_process_if_block doesn't call the
1247 functions involved. Ifdef code, however, should be discouraged
1248 because it leads to typos in the code not selected. However,
1249 emit_conditional_move won't exist either. */
1254 /* Try only simple constants and registers here. More complex cases
1255 are handled in noce_try_cmove_arith after noce_try_store_flag_arith
1256 has had a go at it. */
1259 noce_try_cmove (struct noce_if_info *if_info)
1264 if ((CONSTANT_P (if_info->a) || register_operand (if_info->a, VOIDmode))
1265 && (CONSTANT_P (if_info->b) || register_operand (if_info->b, VOIDmode)))
1269 code = GET_CODE (if_info->cond);
1270 target = noce_emit_cmove (if_info, if_info->x, code,
1271 XEXP (if_info->cond, 0),
1272 XEXP (if_info->cond, 1),
1273 if_info->a, if_info->b);
1277 if (target != if_info->x)
1278 noce_emit_move_insn (if_info->x, target);
1280 seq = end_ifcvt_sequence (if_info);
1284 emit_insn_before_setloc (seq, if_info->jump,
1285 INSN_LOCATOR (if_info->insn_a));
1298 /* Try more complex cases involving conditional_move. */
1301 noce_try_cmove_arith (struct noce_if_info *if_info)
1313 /* A conditional move from two memory sources is equivalent to a
1314 conditional on their addresses followed by a load. Don't do this
1315 early because it'll screw alias analysis. Note that we've
1316 already checked for no side effects. */
1317 /* ??? FIXME: Magic number 5. */
1318 if (cse_not_expected
1319 && MEM_P (a) && MEM_P (b)
1320 && BRANCH_COST >= 5)
1324 x = gen_reg_rtx (Pmode);
1328 /* ??? We could handle this if we knew that a load from A or B could
1329 not fault. This is also true if we've already loaded
1330 from the address along the path from ENTRY. */
1331 else if (may_trap_p (a) || may_trap_p (b))
1334 /* if (test) x = a + b; else x = c - d;
1341 code = GET_CODE (if_info->cond);
1342 insn_a = if_info->insn_a;
1343 insn_b = if_info->insn_b;
1345 /* Total insn_rtx_cost should be smaller than branch cost. Exit
1346 if insn_rtx_cost can't be estimated. */
1349 insn_cost = insn_rtx_cost (PATTERN (insn_a));
1350 if (insn_cost == 0 || insn_cost > COSTS_N_INSNS (BRANCH_COST))
1358 insn_cost += insn_rtx_cost (PATTERN (insn_b));
1359 if (insn_cost == 0 || insn_cost > COSTS_N_INSNS (BRANCH_COST))
1363 /* Possibly rearrange operands to make things come out more natural. */
1364 if (reversed_comparison_code (if_info->cond, if_info->jump) != UNKNOWN)
1367 if (rtx_equal_p (b, x))
1369 else if (general_operand (b, GET_MODE (b)))
1374 code = reversed_comparison_code (if_info->cond, if_info->jump);
1375 tmp = a, a = b, b = tmp;
1376 tmp = insn_a, insn_a = insn_b, insn_b = tmp;
1385 /* If either operand is complex, load it into a register first.
1386 The best way to do this is to copy the original insn. In this
1387 way we preserve any clobbers etc that the insn may have had.
1388 This is of course not possible in the IS_MEM case. */
1389 if (! general_operand (a, GET_MODE (a)))
1395 tmp = gen_reg_rtx (GET_MODE (a));
1396 tmp = emit_insn (gen_rtx_SET (VOIDmode, tmp, a));
1399 goto end_seq_and_fail;
1402 a = gen_reg_rtx (GET_MODE (a));
1403 tmp = copy_rtx (insn_a);
1404 set = single_set (tmp);
1406 tmp = emit_insn (PATTERN (tmp));
1408 if (recog_memoized (tmp) < 0)
1409 goto end_seq_and_fail;
1411 if (! general_operand (b, GET_MODE (b)))
1417 tmp = gen_reg_rtx (GET_MODE (b));
1418 tmp = gen_rtx_SET (VOIDmode, tmp, b);
1421 goto end_seq_and_fail;
1424 b = gen_reg_rtx (GET_MODE (b));
1425 tmp = copy_rtx (insn_b);
1426 set = single_set (tmp);
1428 tmp = PATTERN (tmp);
1431 /* If insn to set up A clobbers any registers B depends on, try to
1432 swap insn that sets up A with the one that sets up B. If even
1433 that doesn't help, punt. */
1434 last = get_last_insn ();
1435 if (last && modified_in_p (orig_b, last))
1437 tmp = emit_insn_before (tmp, get_insns ());
1438 if (modified_in_p (orig_a, tmp))
1439 goto end_seq_and_fail;
1442 tmp = emit_insn (tmp);
1444 if (recog_memoized (tmp) < 0)
1445 goto end_seq_and_fail;
1448 target = noce_emit_cmove (if_info, x, code, XEXP (if_info->cond, 0),
1449 XEXP (if_info->cond, 1), a, b);
1452 goto end_seq_and_fail;
1454 /* If we're handling a memory for above, emit the load now. */
1457 tmp = gen_rtx_MEM (GET_MODE (if_info->x), target);
1459 /* Copy over flags as appropriate. */
1460 if (MEM_VOLATILE_P (if_info->a) || MEM_VOLATILE_P (if_info->b))
1461 MEM_VOLATILE_P (tmp) = 1;
1462 if (MEM_IN_STRUCT_P (if_info->a) && MEM_IN_STRUCT_P (if_info->b))
1463 MEM_IN_STRUCT_P (tmp) = 1;
1464 if (MEM_SCALAR_P (if_info->a) && MEM_SCALAR_P (if_info->b))
1465 MEM_SCALAR_P (tmp) = 1;
1466 if (MEM_ALIAS_SET (if_info->a) == MEM_ALIAS_SET (if_info->b))
1467 set_mem_alias_set (tmp, MEM_ALIAS_SET (if_info->a));
1469 MIN (MEM_ALIGN (if_info->a), MEM_ALIGN (if_info->b)));
1471 noce_emit_move_insn (if_info->x, tmp);
1473 else if (target != x)
1474 noce_emit_move_insn (x, target);
1476 tmp = end_ifcvt_sequence (if_info);
1480 emit_insn_before_setloc (tmp, if_info->jump, INSN_LOCATOR (if_info->insn_a));
1488 /* For most cases, the simplified condition we found is the best
1489 choice, but this is not the case for the min/max/abs transforms.
1490 For these we wish to know that it is A or B in the condition. */
1493 noce_get_alt_condition (struct noce_if_info *if_info, rtx target,
1496 rtx cond, set, insn;
1499 /* If target is already mentioned in the known condition, return it. */
1500 if (reg_mentioned_p (target, if_info->cond))
1502 *earliest = if_info->cond_earliest;
1503 return if_info->cond;
1506 set = pc_set (if_info->jump);
1507 cond = XEXP (SET_SRC (set), 0);
1509 = GET_CODE (XEXP (SET_SRC (set), 2)) == LABEL_REF
1510 && XEXP (XEXP (SET_SRC (set), 2), 0) == JUMP_LABEL (if_info->jump);
1511 if (if_info->then_else_reversed)
1514 /* If we're looking for a constant, try to make the conditional
1515 have that constant in it. There are two reasons why it may
1516 not have the constant we want:
1518 1. GCC may have needed to put the constant in a register, because
1519 the target can't compare directly against that constant. For
1520 this case, we look for a SET immediately before the comparison
1521 that puts a constant in that register.
1523 2. GCC may have canonicalized the conditional, for example
1524 replacing "if x < 4" with "if x <= 3". We can undo that (or
1525 make equivalent types of changes) to get the constants we need
1526 if they're off by one in the right direction. */
1528 if (GET_CODE (target) == CONST_INT)
1530 enum rtx_code code = GET_CODE (if_info->cond);
1531 rtx op_a = XEXP (if_info->cond, 0);
1532 rtx op_b = XEXP (if_info->cond, 1);
1535 /* First, look to see if we put a constant in a register. */
1536 prev_insn = prev_nonnote_insn (if_info->cond_earliest);
1538 && BLOCK_NUM (prev_insn) == BLOCK_NUM (if_info->cond_earliest)
1539 && INSN_P (prev_insn)
1540 && GET_CODE (PATTERN (prev_insn)) == SET)
1542 rtx src = find_reg_equal_equiv_note (prev_insn);
1544 src = SET_SRC (PATTERN (prev_insn));
1545 if (GET_CODE (src) == CONST_INT)
1547 if (rtx_equal_p (op_a, SET_DEST (PATTERN (prev_insn))))
1549 else if (rtx_equal_p (op_b, SET_DEST (PATTERN (prev_insn))))
1552 if (GET_CODE (op_a) == CONST_INT)
1557 code = swap_condition (code);
1562 /* Now, look to see if we can get the right constant by
1563 adjusting the conditional. */
1564 if (GET_CODE (op_b) == CONST_INT)
1566 HOST_WIDE_INT desired_val = INTVAL (target);
1567 HOST_WIDE_INT actual_val = INTVAL (op_b);
1572 if (actual_val == desired_val + 1)
1575 op_b = GEN_INT (desired_val);
1579 if (actual_val == desired_val - 1)
1582 op_b = GEN_INT (desired_val);
1586 if (actual_val == desired_val - 1)
1589 op_b = GEN_INT (desired_val);
1593 if (actual_val == desired_val + 1)
1596 op_b = GEN_INT (desired_val);
1604 /* If we made any changes, generate a new conditional that is
1605 equivalent to what we started with, but has the right
1607 if (code != GET_CODE (if_info->cond)
1608 || op_a != XEXP (if_info->cond, 0)
1609 || op_b != XEXP (if_info->cond, 1))
1611 cond = gen_rtx_fmt_ee (code, GET_MODE (cond), op_a, op_b);
1612 *earliest = if_info->cond_earliest;
1617 cond = canonicalize_condition (if_info->jump, cond, reverse,
1618 earliest, target, false, true);
1619 if (! cond || ! reg_mentioned_p (target, cond))
1622 /* We almost certainly searched back to a different place.
1623 Need to re-verify correct lifetimes. */
1625 /* X may not be mentioned in the range (cond_earliest, jump]. */
1626 for (insn = if_info->jump; insn != *earliest; insn = PREV_INSN (insn))
1627 if (INSN_P (insn) && reg_overlap_mentioned_p (if_info->x, PATTERN (insn)))
1630 /* A and B may not be modified in the range [cond_earliest, jump). */
1631 for (insn = *earliest; insn != if_info->jump; insn = NEXT_INSN (insn))
1633 && (modified_in_p (if_info->a, insn)
1634 || modified_in_p (if_info->b, insn)))
1640 /* Convert "if (a < b) x = a; else x = b;" to "x = min(a, b);", etc. */
1643 noce_try_minmax (struct noce_if_info *if_info)
1645 rtx cond, earliest, target, seq;
1646 enum rtx_code code, op;
1649 /* ??? Reject modes with NaNs or signed zeros since we don't know how
1650 they will be resolved with an SMIN/SMAX. It wouldn't be too hard
1651 to get the target to tell us... */
1652 if (HONOR_SIGNED_ZEROS (GET_MODE (if_info->x))
1653 || HONOR_NANS (GET_MODE (if_info->x)))
1656 cond = noce_get_alt_condition (if_info, if_info->a, &earliest);
1660 /* Verify the condition is of the form we expect, and canonicalize
1661 the comparison code. */
1662 code = GET_CODE (cond);
1663 if (rtx_equal_p (XEXP (cond, 0), if_info->a))
1665 if (! rtx_equal_p (XEXP (cond, 1), if_info->b))
1668 else if (rtx_equal_p (XEXP (cond, 1), if_info->a))
1670 if (! rtx_equal_p (XEXP (cond, 0), if_info->b))
1672 code = swap_condition (code);
1677 /* Determine what sort of operation this is. Note that the code is for
1678 a taken branch, so the code->operation mapping appears backwards. */
1711 target = expand_simple_binop (GET_MODE (if_info->x), op,
1712 if_info->a, if_info->b,
1713 if_info->x, unsignedp, OPTAB_WIDEN);
1719 if (target != if_info->x)
1720 noce_emit_move_insn (if_info->x, target);
1722 seq = end_ifcvt_sequence (if_info);
1726 emit_insn_before_setloc (seq, if_info->jump, INSN_LOCATOR (if_info->insn_a));
1727 if_info->cond = cond;
1728 if_info->cond_earliest = earliest;
1733 /* Convert "if (a < 0) x = -a; else x = a;" to "x = abs(a);", etc. */
1736 noce_try_abs (struct noce_if_info *if_info)
1738 rtx cond, earliest, target, seq, a, b, c;
1741 /* Recognize A and B as constituting an ABS or NABS. The canonical
1742 form is a branch around the negation, taken when the object is the
1743 first operand of a comparison against 0 that evaluates to true. */
1746 if (GET_CODE (a) == NEG && rtx_equal_p (XEXP (a, 0), b))
1748 else if (GET_CODE (b) == NEG && rtx_equal_p (XEXP (b, 0), a))
1750 c = a; a = b; b = c;
1756 cond = noce_get_alt_condition (if_info, b, &earliest);
1760 /* Verify the condition is of the form we expect. */
1761 if (rtx_equal_p (XEXP (cond, 0), b))
1763 else if (rtx_equal_p (XEXP (cond, 1), b))
1771 /* Verify that C is zero. Search one step backward for a
1772 REG_EQUAL note or a simple source if necessary. */
1775 rtx set, insn = prev_nonnote_insn (earliest);
1777 && BLOCK_NUM (insn) == BLOCK_NUM (earliest)
1778 && (set = single_set (insn))
1779 && rtx_equal_p (SET_DEST (set), c))
1781 rtx note = find_reg_equal_equiv_note (insn);
1791 && GET_CODE (XEXP (c, 0)) == SYMBOL_REF
1792 && CONSTANT_POOL_ADDRESS_P (XEXP (c, 0)))
1793 c = get_pool_constant (XEXP (c, 0));
1795 /* Work around funny ideas get_condition has wrt canonicalization.
1796 Note that these rtx constants are known to be CONST_INT, and
1797 therefore imply integer comparisons. */
1798 if (c == constm1_rtx && GET_CODE (cond) == GT)
1800 else if (c == const1_rtx && GET_CODE (cond) == LT)
1802 else if (c != CONST0_RTX (GET_MODE (b)))
1805 /* Determine what sort of operation this is. */
1806 switch (GET_CODE (cond))
1825 target = expand_abs_nojump (GET_MODE (if_info->x), b, if_info->x, 1);
1827 /* ??? It's a quandary whether cmove would be better here, especially
1828 for integers. Perhaps combine will clean things up. */
1829 if (target && negate)
1830 target = expand_simple_unop (GET_MODE (target), NEG, target, if_info->x, 0);
1838 if (target != if_info->x)
1839 noce_emit_move_insn (if_info->x, target);
1841 seq = end_ifcvt_sequence (if_info);
1845 emit_insn_before_setloc (seq, if_info->jump, INSN_LOCATOR (if_info->insn_a));
1846 if_info->cond = cond;
1847 if_info->cond_earliest = earliest;
1852 /* Convert "if (m < 0) x = b; else x = 0;" to "x = (m >> C) & b;". */
1855 noce_try_sign_mask (struct noce_if_info *if_info)
1857 rtx cond, t, m, c, seq;
1858 enum machine_mode mode;
1860 bool b_unconditional;
1862 cond = if_info->cond;
1863 code = GET_CODE (cond);
1868 if (if_info->a == const0_rtx)
1870 if ((code == LT && c == const0_rtx)
1871 || (code == LE && c == constm1_rtx))
1874 else if (if_info->b == const0_rtx)
1876 if ((code == GE && c == const0_rtx)
1877 || (code == GT && c == constm1_rtx))
1881 if (! t || side_effects_p (t))
1884 /* We currently don't handle different modes. */
1885 mode = GET_MODE (t);
1886 if (GET_MODE (m) != mode)
1889 /* This is only profitable if T is cheap, or T is unconditionally
1890 executed/evaluated in the original insn sequence. The latter
1891 happens if INSN_B was taken from TEST_BB, or if there was no
1892 INSN_B which can happen for e.g. conditional stores to memory. */
1893 b_unconditional = (if_info->insn_b == NULL_RTX
1894 || BLOCK_FOR_INSN (if_info->insn_b) == if_info->test_bb);
1895 if (rtx_cost (t, SET) >= COSTS_N_INSNS (2)
1896 && (!b_unconditional
1897 || t != if_info->b))
1901 /* Use emit_store_flag to generate "m < 0 ? -1 : 0" instead of expanding
1902 "(signed) m >> 31" directly. This benefits targets with specialized
1903 insns to obtain the signmask, but still uses ashr_optab otherwise. */
1904 m = emit_store_flag (gen_reg_rtx (mode), LT, m, const0_rtx, mode, 0, -1);
1905 t = m ? expand_binop (mode, and_optab, m, t, NULL_RTX, 0, OPTAB_DIRECT)
1914 noce_emit_move_insn (if_info->x, t);
1916 seq = end_ifcvt_sequence (if_info);
1920 emit_insn_before_setloc (seq, if_info->jump, INSN_LOCATOR (if_info->insn_a));
1925 /* Optimize away "if (x & C) x |= C" and similar bit manipulation
1929 noce_try_bitop (struct noce_if_info *if_info)
1931 rtx cond, x, a, result, seq;
1932 enum machine_mode mode;
1937 cond = if_info->cond;
1938 code = GET_CODE (cond);
1940 /* Check for no else condition. */
1941 if (! rtx_equal_p (x, if_info->b))
1944 /* Check for a suitable condition. */
1945 if (code != NE && code != EQ)
1947 if (XEXP (cond, 1) != const0_rtx)
1949 cond = XEXP (cond, 0);
1951 /* ??? We could also handle AND here. */
1952 if (GET_CODE (cond) == ZERO_EXTRACT)
1954 if (XEXP (cond, 1) != const1_rtx
1955 || GET_CODE (XEXP (cond, 2)) != CONST_INT
1956 || ! rtx_equal_p (x, XEXP (cond, 0)))
1958 bitnum = INTVAL (XEXP (cond, 2));
1959 mode = GET_MODE (x);
1960 if (BITS_BIG_ENDIAN)
1961 bitnum = GET_MODE_BITSIZE (mode) - 1 - bitnum;
1962 if (bitnum < 0 || bitnum >= HOST_BITS_PER_WIDE_INT)
1969 if (GET_CODE (a) == IOR || GET_CODE (a) == XOR)
1971 /* Check for "if (X & C) x = x op C". */
1972 if (! rtx_equal_p (x, XEXP (a, 0))
1973 || GET_CODE (XEXP (a, 1)) != CONST_INT
1974 || (INTVAL (XEXP (a, 1)) & GET_MODE_MASK (mode))
1975 != (unsigned HOST_WIDE_INT) 1 << bitnum)
1978 /* if ((x & C) == 0) x |= C; is transformed to x |= C. */
1979 /* if ((x & C) != 0) x |= C; is transformed to nothing. */
1980 if (GET_CODE (a) == IOR)
1981 result = (code == NE) ? a : NULL_RTX;
1982 else if (code == NE)
1984 /* if ((x & C) == 0) x ^= C; is transformed to x |= C. */
1985 result = gen_int_mode ((HOST_WIDE_INT) 1 << bitnum, mode);
1986 result = simplify_gen_binary (IOR, mode, x, result);
1990 /* if ((x & C) != 0) x ^= C; is transformed to x &= ~C. */
1991 result = gen_int_mode (~((HOST_WIDE_INT) 1 << bitnum), mode);
1992 result = simplify_gen_binary (AND, mode, x, result);
1995 else if (GET_CODE (a) == AND)
1997 /* Check for "if (X & C) x &= ~C". */
1998 if (! rtx_equal_p (x, XEXP (a, 0))
1999 || GET_CODE (XEXP (a, 1)) != CONST_INT
2000 || (INTVAL (XEXP (a, 1)) & GET_MODE_MASK (mode))
2001 != (~((HOST_WIDE_INT) 1 << bitnum) & GET_MODE_MASK (mode)))
2004 /* if ((x & C) == 0) x &= ~C; is transformed to nothing. */
2005 /* if ((x & C) != 0) x &= ~C; is transformed to x &= ~C. */
2006 result = (code == EQ) ? a : NULL_RTX;
2014 noce_emit_move_insn (x, result);
2015 seq = end_ifcvt_sequence (if_info);
2019 emit_insn_before_setloc (seq, if_info->jump,
2020 INSN_LOCATOR (if_info->insn_a));
2026 /* Similar to get_condition, only the resulting condition must be
2027 valid at JUMP, instead of at EARLIEST.
2029 If THEN_ELSE_REVERSED is true, the fallthrough does not go to the
2030 THEN block of the caller, and we have to reverse the condition. */
2033 noce_get_condition (rtx jump, rtx *earliest, bool then_else_reversed)
2038 if (! any_condjump_p (jump))
2041 set = pc_set (jump);
2043 /* If this branches to JUMP_LABEL when the condition is false,
2044 reverse the condition. */
2045 reverse = (GET_CODE (XEXP (SET_SRC (set), 2)) == LABEL_REF
2046 && XEXP (XEXP (SET_SRC (set), 2), 0) == JUMP_LABEL (jump));
2048 /* We may have to reverse because the caller's if block is not canonical,
2049 i.e. the THEN block isn't the fallthrough block for the TEST block
2050 (see find_if_header). */
2051 if (then_else_reversed)
2054 /* If the condition variable is a register and is MODE_INT, accept it. */
2056 cond = XEXP (SET_SRC (set), 0);
2057 tmp = XEXP (cond, 0);
2058 if (REG_P (tmp) && GET_MODE_CLASS (GET_MODE (tmp)) == MODE_INT)
2063 cond = gen_rtx_fmt_ee (reverse_condition (GET_CODE (cond)),
2064 GET_MODE (cond), tmp, XEXP (cond, 1));
2068 /* Otherwise, fall back on canonicalize_condition to do the dirty
2069 work of manipulating MODE_CC values and COMPARE rtx codes. */
2070 return canonicalize_condition (jump, cond, reverse, earliest,
2071 NULL_RTX, false, true);
2074 /* Return true if OP is ok for if-then-else processing. */
2077 noce_operand_ok (const_rtx op)
2079 /* We special-case memories, so handle any of them with
2080 no address side effects. */
2082 return ! side_effects_p (XEXP (op, 0));
2084 if (side_effects_p (op))
2087 return ! may_trap_p (op);
2090 /* Return true if a write into MEM may trap or fault. */
2093 noce_mem_write_may_trap_or_fault_p (const_rtx mem)
2097 if (MEM_READONLY_P (mem))
2100 if (may_trap_or_fault_p (mem))
2103 addr = XEXP (mem, 0);
2105 /* Call target hook to avoid the effects of -fpic etc.... */
2106 addr = targetm.delegitimize_address (addr);
2109 switch (GET_CODE (addr))
2117 addr = XEXP (addr, 0);
2121 addr = XEXP (addr, 1);
2124 if (GET_CODE (XEXP (addr, 1)) == CONST_INT)
2125 addr = XEXP (addr, 0);
2132 if (SYMBOL_REF_DECL (addr)
2133 && decl_readonly_section (SYMBOL_REF_DECL (addr), 0))
2143 /* Return whether we can use store speculation for MEM. TOP_BB is the
2144 basic block above the conditional block where we are considering
2145 doing the speculative store. We look for whether MEM is set
2146 unconditionally later in the function. */
2149 noce_can_store_speculate_p (basic_block top_bb, const_rtx mem)
2151 basic_block dominator;
2153 for (dominator = get_immediate_dominator (CDI_POST_DOMINATORS, top_bb);
2155 dominator = get_immediate_dominator (CDI_POST_DOMINATORS, dominator))
2159 FOR_BB_INSNS (dominator, insn)
2161 /* If we see something that might be a memory barrier, we
2162 have to stop looking. Even if the MEM is set later in
2163 the function, we still don't want to set it
2164 unconditionally before the barrier. */
2166 && (volatile_insn_p (PATTERN (insn))
2168 && (!CONST_OR_PURE_CALL_P (insn)
2169 || pure_call_p (insn)))))
2172 if (memory_modified_in_insn_p (mem, insn))
2174 if (modified_in_p (XEXP (mem, 0), insn))
2183 /* Given a simple IF-THEN-JOIN or IF-THEN-ELSE-JOIN block, attempt to convert
2184 it without using conditional execution. Return TRUE if we were successful
2185 at converting the block. */
2188 noce_process_if_block (struct noce_if_info *if_info)
2190 basic_block test_bb = if_info->test_bb; /* test block */
2191 basic_block then_bb = if_info->then_bb; /* THEN */
2192 basic_block else_bb = if_info->else_bb; /* ELSE or NULL */
2193 basic_block join_bb = if_info->join_bb; /* JOIN */
2194 rtx jump = if_info->jump;
2195 rtx cond = if_info->cond;
2198 rtx orig_x, x, a, b;
2200 /* We're looking for patterns of the form
2202 (1) if (...) x = a; else x = b;
2203 (2) x = b; if (...) x = a;
2204 (3) if (...) x = a; // as if with an initial x = x.
2206 The later patterns require jumps to be more expensive.
2208 ??? For future expansion, look for multiple X in such patterns. */
2210 /* Look for one of the potential sets. */
2211 insn_a = first_active_insn (then_bb);
2213 || insn_a != last_active_insn (then_bb, FALSE)
2214 || (set_a = single_set (insn_a)) == NULL_RTX)
2217 x = SET_DEST (set_a);
2218 a = SET_SRC (set_a);
2220 /* Look for the other potential set. Make sure we've got equivalent
2222 /* ??? This is overconservative. Storing to two different mems is
2223 as easy as conditionally computing the address. Storing to a
2224 single mem merely requires a scratch memory to use as one of the
2225 destination addresses; often the memory immediately below the
2226 stack pointer is available for this. */
2230 insn_b = first_active_insn (else_bb);
2232 || insn_b != last_active_insn (else_bb, FALSE)
2233 || (set_b = single_set (insn_b)) == NULL_RTX
2234 || ! rtx_equal_p (x, SET_DEST (set_b)))
2239 insn_b = prev_nonnote_insn (if_info->cond_earliest);
2240 /* We're going to be moving the evaluation of B down from above
2241 COND_EARLIEST to JUMP. Make sure the relevant data is still
2244 || BLOCK_NUM (insn_b) != BLOCK_NUM (if_info->cond_earliest)
2245 || !NONJUMP_INSN_P (insn_b)
2246 || (set_b = single_set (insn_b)) == NULL_RTX
2247 || ! rtx_equal_p (x, SET_DEST (set_b))
2248 || ! noce_operand_ok (SET_SRC (set_b))
2249 || reg_overlap_mentioned_p (x, SET_SRC (set_b))
2250 || modified_between_p (SET_SRC (set_b),
2251 PREV_INSN (if_info->cond_earliest), jump)
2252 /* Likewise with X. In particular this can happen when
2253 noce_get_condition looks farther back in the instruction
2254 stream than one might expect. */
2255 || reg_overlap_mentioned_p (x, cond)
2256 || reg_overlap_mentioned_p (x, a)
2257 || modified_between_p (x, PREV_INSN (if_info->cond_earliest), jump))
2258 insn_b = set_b = NULL_RTX;
2261 /* If x has side effects then only the if-then-else form is safe to
2262 convert. But even in that case we would need to restore any notes
2263 (such as REG_INC) at then end. That can be tricky if
2264 noce_emit_move_insn expands to more than one insn, so disable the
2265 optimization entirely for now if there are side effects. */
2266 if (side_effects_p (x))
2269 b = (set_b ? SET_SRC (set_b) : x);
2271 /* Only operate on register destinations, and even then avoid extending
2272 the lifetime of hard registers on small register class machines. */
2275 || (SMALL_REGISTER_CLASSES
2276 && REGNO (x) < FIRST_PSEUDO_REGISTER))
2278 if (GET_MODE (x) == BLKmode)
2281 if (GET_MODE (x) == ZERO_EXTRACT
2282 && (GET_CODE (XEXP (x, 1)) != CONST_INT
2283 || GET_CODE (XEXP (x, 2)) != CONST_INT))
2286 x = gen_reg_rtx (GET_MODE (GET_CODE (x) == STRICT_LOW_PART
2287 ? XEXP (x, 0) : x));
2290 /* Don't operate on sources that may trap or are volatile. */
2291 if (! noce_operand_ok (a) || ! noce_operand_ok (b))
2295 /* Set up the info block for our subroutines. */
2296 if_info->insn_a = insn_a;
2297 if_info->insn_b = insn_b;
2302 /* Try optimizations in some approximation of a useful order. */
2303 /* ??? Should first look to see if X is live incoming at all. If it
2304 isn't, we don't need anything but an unconditional set. */
2306 /* Look and see if A and B are really the same. Avoid creating silly
2307 cmove constructs that no one will fix up later. */
2308 if (rtx_equal_p (a, b))
2310 /* If we have an INSN_B, we don't have to create any new rtl. Just
2311 move the instruction that we already have. If we don't have an
2312 INSN_B, that means that A == X, and we've got a noop move. In
2313 that case don't do anything and let the code below delete INSN_A. */
2314 if (insn_b && else_bb)
2318 if (else_bb && insn_b == BB_END (else_bb))
2319 BB_END (else_bb) = PREV_INSN (insn_b);
2320 reorder_insns (insn_b, insn_b, PREV_INSN (jump));
2322 /* If there was a REG_EQUAL note, delete it since it may have been
2323 true due to this insn being after a jump. */
2324 if ((note = find_reg_note (insn_b, REG_EQUAL, NULL_RTX)) != 0)
2325 remove_note (insn_b, note);
2329 /* If we have "x = b; if (...) x = a;", and x has side-effects, then
2330 x must be executed twice. */
2331 else if (insn_b && side_effects_p (orig_x))
2338 if (!set_b && MEM_P (orig_x))
2340 /* Disallow the "if (...) x = a;" form (implicit "else x = x;")
2341 for optimizations if writing to x may trap or fault,
2342 i.e. it's a memory other than a static var or a stack slot,
2343 is misaligned on strict aligned machines or is read-only. If
2344 x is a read-only memory, then the program is valid only if we
2345 avoid the store into it. If there are stores on both the
2346 THEN and ELSE arms, then we can go ahead with the conversion;
2347 either the program is broken, or the condition is always
2348 false such that the other memory is selected. */
2349 if (noce_mem_write_may_trap_or_fault_p (orig_x))
2352 /* Avoid store speculation: given "if (...) x = a" where x is a
2353 MEM, we only want to do the store if x is always set
2354 somewhere in the function. This avoids cases like
2355 if (pthread_mutex_trylock(mutex))
2357 where we only want global_variable to be changed if the mutex
2358 is held. FIXME: This should ideally be expressed directly in
2360 if (!noce_can_store_speculate_p (test_bb, orig_x))
2364 if (noce_try_move (if_info))
2366 if (noce_try_store_flag (if_info))
2368 if (noce_try_bitop (if_info))
2370 if (noce_try_minmax (if_info))
2372 if (noce_try_abs (if_info))
2374 if (HAVE_conditional_move
2375 && noce_try_cmove (if_info))
2377 if (! HAVE_conditional_execution)
2379 if (noce_try_store_flag_constants (if_info))
2381 if (noce_try_addcc (if_info))
2383 if (noce_try_store_flag_mask (if_info))
2385 if (HAVE_conditional_move
2386 && noce_try_cmove_arith (if_info))
2388 if (noce_try_sign_mask (if_info))
2392 if (!else_bb && set_b)
2394 insn_b = set_b = NULL_RTX;
2403 /* If we used a temporary, fix it up now. */
2409 noce_emit_move_insn (orig_x, x);
2411 set_used_flags (orig_x);
2412 unshare_all_rtl_in_chain (seq);
2415 emit_insn_before_setloc (seq, BB_END (test_bb), INSN_LOCATOR (insn_a));
2418 /* The original THEN and ELSE blocks may now be removed. The test block
2419 must now jump to the join block. If the test block and the join block
2420 can be merged, do so. */
2423 delete_basic_block (else_bb);
2427 remove_edge (find_edge (test_bb, join_bb));
2429 remove_edge (find_edge (then_bb, join_bb));
2430 redirect_edge_and_branch_force (single_succ_edge (test_bb), join_bb);
2431 delete_basic_block (then_bb);
2434 if (can_merge_blocks_p (test_bb, join_bb))
2436 merge_blocks (test_bb, join_bb);
2440 num_updated_if_blocks++;
2444 /* Check whether a block is suitable for conditional move conversion.
2445 Every insn must be a simple set of a register to a constant or a
2446 register. For each assignment, store the value in the array VALS,
2447 indexed by register number, then store the register number in
2448 REGS. COND is the condition we will test. */
2451 check_cond_move_block (basic_block bb, rtx *vals, VEC (int, heap) *regs, rtx cond)
2455 /* We can only handle simple jumps at the end of the basic block.
2456 It is almost impossible to update the CFG otherwise. */
2458 if (JUMP_P (insn) && !onlyjump_p (insn))
2461 FOR_BB_INSNS (bb, insn)
2465 if (!INSN_P (insn) || JUMP_P (insn))
2467 set = single_set (insn);
2471 dest = SET_DEST (set);
2472 src = SET_SRC (set);
2474 || (SMALL_REGISTER_CLASSES && HARD_REGISTER_P (dest)))
2477 if (!CONSTANT_P (src) && !register_operand (src, VOIDmode))
2480 if (side_effects_p (src) || side_effects_p (dest))
2483 if (may_trap_p (src) || may_trap_p (dest))
2486 /* Don't try to handle this if the source register was
2487 modified earlier in the block. */
2489 && vals[REGNO (src)] != NULL)
2490 || (GET_CODE (src) == SUBREG && REG_P (SUBREG_REG (src))
2491 && vals[REGNO (SUBREG_REG (src))] != NULL))
2494 /* Don't try to handle this if the destination register was
2495 modified earlier in the block. */
2496 if (vals[REGNO (dest)] != NULL)
2499 /* Don't try to handle this if the condition uses the
2500 destination register. */
2501 if (reg_overlap_mentioned_p (dest, cond))
2504 /* Don't try to handle this if the source register is modified
2505 later in the block. */
2506 if (!CONSTANT_P (src)
2507 && modified_between_p (src, insn, NEXT_INSN (BB_END (bb))))
2510 vals[REGNO (dest)] = src;
2512 VEC_safe_push (int, heap, regs, REGNO (dest));
2518 /* Given a basic block BB suitable for conditional move conversion,
2519 a condition COND, and arrays THEN_VALS and ELSE_VALS containing the
2520 register values depending on COND, emit the insns in the block as
2521 conditional moves. If ELSE_BLOCK is true, THEN_BB was already
2522 processed. The caller has started a sequence for the conversion.
2523 Return true if successful, false if something goes wrong. */
2526 cond_move_convert_if_block (struct noce_if_info *if_infop,
2527 basic_block bb, rtx cond,
2528 rtx *then_vals, rtx *else_vals,
2532 rtx insn, cond_arg0, cond_arg1;
2534 code = GET_CODE (cond);
2535 cond_arg0 = XEXP (cond, 0);
2536 cond_arg1 = XEXP (cond, 1);
2538 FOR_BB_INSNS (bb, insn)
2540 rtx set, target, dest, t, e;
2543 if (!INSN_P (insn) || JUMP_P (insn))
2545 set = single_set (insn);
2546 gcc_assert (set && REG_P (SET_DEST (set)));
2548 dest = SET_DEST (set);
2549 regno = REGNO (dest);
2551 t = then_vals[regno];
2552 e = else_vals[regno];
2556 /* If this register was set in the then block, we already
2557 handled this case there. */
2570 target = noce_emit_cmove (if_infop, dest, code, cond_arg0, cond_arg1,
2576 noce_emit_move_insn (dest, target);
2582 /* Given a simple IF-THEN-JOIN or IF-THEN-ELSE-JOIN block, attempt to convert
2583 it using only conditional moves. Return TRUE if we were successful at
2584 converting the block. */
2587 cond_move_process_if_block (struct noce_if_info *if_info)
2589 basic_block test_bb = if_info->test_bb;
2590 basic_block then_bb = if_info->then_bb;
2591 basic_block else_bb = if_info->else_bb;
2592 basic_block join_bb = if_info->join_bb;
2593 rtx jump = if_info->jump;
2594 rtx cond = if_info->cond;
2596 int max_reg, size, c, reg;
2599 VEC (int, heap) *then_regs = NULL;
2600 VEC (int, heap) *else_regs = NULL;
2603 /* Build a mapping for each block to the value used for each
2605 max_reg = max_reg_num ();
2606 size = (max_reg + 1) * sizeof (rtx);
2607 then_vals = (rtx *) alloca (size);
2608 else_vals = (rtx *) alloca (size);
2609 memset (then_vals, 0, size);
2610 memset (else_vals, 0, size);
2612 /* Make sure the blocks are suitable. */
2613 if (!check_cond_move_block (then_bb, then_vals, then_regs, cond)
2614 || (else_bb && !check_cond_move_block (else_bb, else_vals, else_regs, cond)))
2617 /* Make sure the blocks can be used together. If the same register
2618 is set in both blocks, and is not set to a constant in both
2619 cases, then both blocks must set it to the same register. We
2620 have already verified that if it is set to a register, that the
2621 source register does not change after the assignment. Also count
2622 the number of registers set in only one of the blocks. */
2624 for (i = 0; VEC_iterate (int, then_regs, i, reg); i++)
2626 if (!then_vals[reg] && !else_vals[reg])
2629 if (!else_vals[reg])
2633 if (!CONSTANT_P (then_vals[reg])
2634 && !CONSTANT_P (else_vals[reg])
2635 && !rtx_equal_p (then_vals[reg], else_vals[reg]))
2640 /* Finish off c for MAX_CONDITIONAL_EXECUTE. */
2641 for (i = 0; VEC_iterate (int, else_regs, i, reg); ++i)
2642 if (!then_vals[reg])
2645 /* Make sure it is reasonable to convert this block. What matters
2646 is the number of assignments currently made in only one of the
2647 branches, since if we convert we are going to always execute
2649 if (c > MAX_CONDITIONAL_EXECUTE)
2652 /* Try to emit the conditional moves. First do the then block,
2653 then do anything left in the else blocks. */
2655 if (!cond_move_convert_if_block (if_info, then_bb, cond,
2656 then_vals, else_vals, false)
2658 && !cond_move_convert_if_block (if_info, else_bb, cond,
2659 then_vals, else_vals, true)))
2664 seq = end_ifcvt_sequence (if_info);
2668 loc_insn = first_active_insn (then_bb);
2671 loc_insn = first_active_insn (else_bb);
2672 gcc_assert (loc_insn);
2674 emit_insn_before_setloc (seq, jump, INSN_LOCATOR (loc_insn));
2678 delete_basic_block (else_bb);
2682 remove_edge (find_edge (test_bb, join_bb));
2684 remove_edge (find_edge (then_bb, join_bb));
2685 redirect_edge_and_branch_force (single_succ_edge (test_bb), join_bb);
2686 delete_basic_block (then_bb);
2689 if (can_merge_blocks_p (test_bb, join_bb))
2691 merge_blocks (test_bb, join_bb);
2695 num_updated_if_blocks++;
2697 VEC_free (int, heap, then_regs);
2698 VEC_free (int, heap, else_regs);
2704 /* Determine if a given basic block heads a simple IF-THEN-JOIN or an
2705 IF-THEN-ELSE-JOIN block.
2707 If so, we'll try to convert the insns to not require the branch,
2708 using only transformations that do not require conditional execution.
2710 Return TRUE if we were successful at converting the block. */
2713 noce_find_if_block (basic_block test_bb,
2714 edge then_edge, edge else_edge,
2717 basic_block then_bb, else_bb, join_bb;
2718 bool then_else_reversed = false;
2721 struct noce_if_info if_info;
2723 /* We only ever should get here before reload. */
2724 gcc_assert (!reload_completed);
2726 /* Recognize an IF-THEN-ELSE-JOIN block. */
2727 if (single_pred_p (then_edge->dest)
2728 && single_succ_p (then_edge->dest)
2729 && single_pred_p (else_edge->dest)
2730 && single_succ_p (else_edge->dest)
2731 && single_succ (then_edge->dest) == single_succ (else_edge->dest))
2733 then_bb = then_edge->dest;
2734 else_bb = else_edge->dest;
2735 join_bb = single_succ (then_bb);
2737 /* Recognize an IF-THEN-JOIN block. */
2738 else if (single_pred_p (then_edge->dest)
2739 && single_succ_p (then_edge->dest)
2740 && single_succ (then_edge->dest) == else_edge->dest)
2742 then_bb = then_edge->dest;
2743 else_bb = NULL_BLOCK;
2744 join_bb = else_edge->dest;
2746 /* Recognize an IF-ELSE-JOIN block. We can have those because the order
2747 of basic blocks in cfglayout mode does not matter, so the fallthrough
2748 edge can go to any basic block (and not just to bb->next_bb, like in
2750 else if (single_pred_p (else_edge->dest)
2751 && single_succ_p (else_edge->dest)
2752 && single_succ (else_edge->dest) == then_edge->dest)
2754 /* The noce transformations do not apply to IF-ELSE-JOIN blocks.
2755 To make this work, we have to invert the THEN and ELSE blocks
2756 and reverse the jump condition. */
2757 then_bb = else_edge->dest;
2758 else_bb = NULL_BLOCK;
2759 join_bb = single_succ (then_bb);
2760 then_else_reversed = true;
2763 /* Not a form we can handle. */
2766 /* The edges of the THEN and ELSE blocks cannot have complex edges. */
2767 if (single_succ_edge (then_bb)->flags & EDGE_COMPLEX)
2770 && single_succ_edge (else_bb)->flags & EDGE_COMPLEX)
2773 num_possible_if_blocks++;
2778 "\nIF-THEN%s-JOIN block found, pass %d, test %d, then %d",
2779 (else_bb) ? "-ELSE" : "",
2780 pass, test_bb->index, then_bb->index);
2783 fprintf (dump_file, ", else %d", else_bb->index);
2785 fprintf (dump_file, ", join %d\n", join_bb->index);
2788 /* If the conditional jump is more than just a conditional
2789 jump, then we can not do if-conversion on this block. */
2790 jump = BB_END (test_bb);
2791 if (! onlyjump_p (jump))
2794 /* If this is not a standard conditional jump, we can't parse it. */
2795 cond = noce_get_condition (jump,
2797 then_else_reversed);
2801 /* We must be comparing objects whose modes imply the size. */
2802 if (GET_MODE (XEXP (cond, 0)) == BLKmode)
2805 /* Initialize an IF_INFO struct to pass around. */
2806 memset (&if_info, 0, sizeof if_info);
2807 if_info.test_bb = test_bb;
2808 if_info.then_bb = then_bb;
2809 if_info.else_bb = else_bb;
2810 if_info.join_bb = join_bb;
2811 if_info.cond = cond;
2812 if_info.cond_earliest = cond_earliest;
2813 if_info.jump = jump;
2814 if_info.then_else_reversed = then_else_reversed;
2816 /* Do the real work. */
2818 if (noce_process_if_block (&if_info))
2821 if (HAVE_conditional_move
2822 && cond_move_process_if_block (&if_info))
2829 /* Merge the blocks and mark for local life update. */
2832 merge_if_block (struct ce_if_block * ce_info)
2834 basic_block test_bb = ce_info->test_bb; /* last test block */
2835 basic_block then_bb = ce_info->then_bb; /* THEN */
2836 basic_block else_bb = ce_info->else_bb; /* ELSE or NULL */
2837 basic_block join_bb = ce_info->join_bb; /* join block */
2838 basic_block combo_bb;
2840 /* All block merging is done into the lower block numbers. */
2843 df_set_bb_dirty (test_bb);
2845 /* Merge any basic blocks to handle && and || subtests. Each of
2846 the blocks are on the fallthru path from the predecessor block. */
2847 if (ce_info->num_multiple_test_blocks > 0)
2849 basic_block bb = test_bb;
2850 basic_block last_test_bb = ce_info->last_test_bb;
2851 basic_block fallthru = block_fallthru (bb);
2856 fallthru = block_fallthru (bb);
2857 merge_blocks (combo_bb, bb);
2860 while (bb != last_test_bb);
2863 /* Merge TEST block into THEN block. Normally the THEN block won't have a
2864 label, but it might if there were || tests. That label's count should be
2865 zero, and it normally should be removed. */
2869 merge_blocks (combo_bb, then_bb);
2873 /* The ELSE block, if it existed, had a label. That label count
2874 will almost always be zero, but odd things can happen when labels
2875 get their addresses taken. */
2878 merge_blocks (combo_bb, else_bb);
2882 /* If there was no join block reported, that means it was not adjacent
2883 to the others, and so we cannot merge them. */
2887 rtx last = BB_END (combo_bb);
2889 /* The outgoing edge for the current COMBO block should already
2890 be correct. Verify this. */
2891 if (EDGE_COUNT (combo_bb->succs) == 0)
2892 gcc_assert (find_reg_note (last, REG_NORETURN, NULL)
2893 || (NONJUMP_INSN_P (last)
2894 && GET_CODE (PATTERN (last)) == TRAP_IF
2895 && (TRAP_CONDITION (PATTERN (last))
2896 == const_true_rtx)));
2899 /* There should still be something at the end of the THEN or ELSE
2900 blocks taking us to our final destination. */
2901 gcc_assert (JUMP_P (last)
2902 || (EDGE_SUCC (combo_bb, 0)->dest == EXIT_BLOCK_PTR
2904 && SIBLING_CALL_P (last))
2905 || ((EDGE_SUCC (combo_bb, 0)->flags & EDGE_EH)
2906 && can_throw_internal (last)));
2909 /* The JOIN block may have had quite a number of other predecessors too.
2910 Since we've already merged the TEST, THEN and ELSE blocks, we should
2911 have only one remaining edge from our if-then-else diamond. If there
2912 is more than one remaining edge, it must come from elsewhere. There
2913 may be zero incoming edges if the THEN block didn't actually join
2914 back up (as with a call to a non-return function). */
2915 else if (EDGE_COUNT (join_bb->preds) < 2
2916 && join_bb != EXIT_BLOCK_PTR)
2918 /* We can merge the JOIN cleanly and update the dataflow try
2919 again on this pass.*/
2920 merge_blocks (combo_bb, join_bb);
2925 /* We cannot merge the JOIN. */
2927 /* The outgoing edge for the current COMBO block should already
2928 be correct. Verify this. */
2929 gcc_assert (single_succ_p (combo_bb)
2930 && single_succ (combo_bb) == join_bb);
2932 /* Remove the jump and cruft from the end of the COMBO block. */
2933 if (join_bb != EXIT_BLOCK_PTR)
2934 tidy_fallthru_edge (single_succ_edge (combo_bb));
2937 num_updated_if_blocks++;
2940 /* Find a block ending in a simple IF condition and try to transform it
2941 in some way. When converting a multi-block condition, put the new code
2942 in the first such block and delete the rest. Return a pointer to this
2943 first block if some transformation was done. Return NULL otherwise. */
2946 find_if_header (basic_block test_bb, int pass)
2948 ce_if_block_t ce_info;
2952 /* The kind of block we're looking for has exactly two successors. */
2953 if (EDGE_COUNT (test_bb->succs) != 2)
2956 then_edge = EDGE_SUCC (test_bb, 0);
2957 else_edge = EDGE_SUCC (test_bb, 1);
2959 if (df_get_bb_dirty (then_edge->dest))
2961 if (df_get_bb_dirty (else_edge->dest))
2964 /* Neither edge should be abnormal. */
2965 if ((then_edge->flags & EDGE_COMPLEX)
2966 || (else_edge->flags & EDGE_COMPLEX))
2969 /* Nor exit the loop. */
2970 if ((then_edge->flags & EDGE_LOOP_EXIT)
2971 || (else_edge->flags & EDGE_LOOP_EXIT))
2974 /* The THEN edge is canonically the one that falls through. */
2975 if (then_edge->flags & EDGE_FALLTHRU)
2977 else if (else_edge->flags & EDGE_FALLTHRU)
2980 else_edge = then_edge;
2984 /* Otherwise this must be a multiway branch of some sort. */
2987 memset (&ce_info, '\0', sizeof (ce_info));
2988 ce_info.test_bb = test_bb;
2989 ce_info.then_bb = then_edge->dest;
2990 ce_info.else_bb = else_edge->dest;
2991 ce_info.pass = pass;
2993 #ifdef IFCVT_INIT_EXTRA_FIELDS
2994 IFCVT_INIT_EXTRA_FIELDS (&ce_info);
2997 if (! reload_completed
2998 && noce_find_if_block (test_bb, then_edge, else_edge, pass))
3001 if (HAVE_conditional_execution && reload_completed
3002 && cond_exec_find_if_block (&ce_info))
3005 if (HAVE_trap && HAVE_conditional_trap
3006 && find_cond_trap (test_bb, then_edge, else_edge))
3009 if (dom_info_state (CDI_POST_DOMINATORS) >= DOM_NO_FAST_QUERY
3010 && (! HAVE_conditional_execution || reload_completed))
3012 if (find_if_case_1 (test_bb, then_edge, else_edge))
3014 if (find_if_case_2 (test_bb, then_edge, else_edge))
3022 fprintf (dump_file, "Conversion succeeded on pass %d.\n", pass);
3023 /* Set this so we continue looking. */
3024 cond_exec_changed_p = TRUE;
3025 return ce_info.test_bb;
3028 /* Return true if a block has two edges, one of which falls through to the next
3029 block, and the other jumps to a specific block, so that we can tell if the
3030 block is part of an && test or an || test. Returns either -1 or the number
3031 of non-note, non-jump, non-USE/CLOBBER insns in the block. */
3034 block_jumps_and_fallthru_p (basic_block cur_bb, basic_block target_bb)
3037 int fallthru_p = FALSE;
3044 if (!cur_bb || !target_bb)
3047 /* If no edges, obviously it doesn't jump or fallthru. */
3048 if (EDGE_COUNT (cur_bb->succs) == 0)
3051 FOR_EACH_EDGE (cur_edge, ei, cur_bb->succs)
3053 if (cur_edge->flags & EDGE_COMPLEX)
3054 /* Anything complex isn't what we want. */
3057 else if (cur_edge->flags & EDGE_FALLTHRU)
3060 else if (cur_edge->dest == target_bb)
3067 if ((jump_p & fallthru_p) == 0)
3070 /* Don't allow calls in the block, since this is used to group && and ||
3071 together for conditional execution support. ??? we should support
3072 conditional execution support across calls for IA-64 some day, but
3073 for now it makes the code simpler. */
3074 end = BB_END (cur_bb);
3075 insn = BB_HEAD (cur_bb);
3077 while (insn != NULL_RTX)
3084 && GET_CODE (PATTERN (insn)) != USE
3085 && GET_CODE (PATTERN (insn)) != CLOBBER)
3091 insn = NEXT_INSN (insn);
3097 /* Determine if a given basic block heads a simple IF-THEN or IF-THEN-ELSE
3098 block. If so, we'll try to convert the insns to not require the branch.
3099 Return TRUE if we were successful at converting the block. */
3102 cond_exec_find_if_block (struct ce_if_block * ce_info)
3104 basic_block test_bb = ce_info->test_bb;
3105 basic_block then_bb = ce_info->then_bb;
3106 basic_block else_bb = ce_info->else_bb;
3107 basic_block join_bb = NULL_BLOCK;
3112 ce_info->last_test_bb = test_bb;
3114 /* We only ever should get here after reload,
3115 and only if we have conditional execution. */
3116 gcc_assert (HAVE_conditional_execution && reload_completed);
3118 /* Discover if any fall through predecessors of the current test basic block
3119 were && tests (which jump to the else block) or || tests (which jump to
3121 if (single_pred_p (test_bb)
3122 && single_pred_edge (test_bb)->flags == EDGE_FALLTHRU)
3124 basic_block bb = single_pred (test_bb);
3125 basic_block target_bb;
3126 int max_insns = MAX_CONDITIONAL_EXECUTE;
3129 /* Determine if the preceding block is an && or || block. */
3130 if ((n_insns = block_jumps_and_fallthru_p (bb, else_bb)) >= 0)
3132 ce_info->and_and_p = TRUE;
3133 target_bb = else_bb;
3135 else if ((n_insns = block_jumps_and_fallthru_p (bb, then_bb)) >= 0)
3137 ce_info->and_and_p = FALSE;
3138 target_bb = then_bb;
3141 target_bb = NULL_BLOCK;
3143 if (target_bb && n_insns <= max_insns)
3145 int total_insns = 0;
3148 ce_info->last_test_bb = test_bb;
3150 /* Found at least one && or || block, look for more. */
3153 ce_info->test_bb = test_bb = bb;
3154 total_insns += n_insns;
3157 if (!single_pred_p (bb))
3160 bb = single_pred (bb);
3161 n_insns = block_jumps_and_fallthru_p (bb, target_bb);
3163 while (n_insns >= 0 && (total_insns + n_insns) <= max_insns);
3165 ce_info->num_multiple_test_blocks = blocks;
3166 ce_info->num_multiple_test_insns = total_insns;
3168 if (ce_info->and_and_p)
3169 ce_info->num_and_and_blocks = blocks;
3171 ce_info->num_or_or_blocks = blocks;
3175 /* The THEN block of an IF-THEN combo must have exactly one predecessor,
3176 other than any || blocks which jump to the THEN block. */
3177 if ((EDGE_COUNT (then_bb->preds) - ce_info->num_or_or_blocks) != 1)
3180 /* The edges of the THEN and ELSE blocks cannot have complex edges. */
3181 FOR_EACH_EDGE (cur_edge, ei, then_bb->preds)
3183 if (cur_edge->flags & EDGE_COMPLEX)
3187 FOR_EACH_EDGE (cur_edge, ei, else_bb->preds)
3189 if (cur_edge->flags & EDGE_COMPLEX)
3193 /* The THEN block of an IF-THEN combo must have zero or one successors. */
3194 if (EDGE_COUNT (then_bb->succs) > 0
3195 && (!single_succ_p (then_bb)
3196 || (single_succ_edge (then_bb)->flags & EDGE_COMPLEX)
3197 || (epilogue_completed && tablejump_p (BB_END (then_bb), NULL, NULL))))
3200 /* If the THEN block has no successors, conditional execution can still
3201 make a conditional call. Don't do this unless the ELSE block has
3202 only one incoming edge -- the CFG manipulation is too ugly otherwise.
3203 Check for the last insn of the THEN block being an indirect jump, which
3204 is listed as not having any successors, but confuses the rest of the CE
3205 code processing. ??? we should fix this in the future. */
3206 if (EDGE_COUNT (then_bb->succs) == 0)
3208 if (single_pred_p (else_bb))
3210 rtx last_insn = BB_END (then_bb);
3213 && NOTE_P (last_insn)
3214 && last_insn != BB_HEAD (then_bb))
3215 last_insn = PREV_INSN (last_insn);
3218 && JUMP_P (last_insn)
3219 && ! simplejump_p (last_insn))
3223 else_bb = NULL_BLOCK;
3229 /* If the THEN block's successor is the other edge out of the TEST block,
3230 then we have an IF-THEN combo without an ELSE. */
3231 else if (single_succ (then_bb) == else_bb)
3234 else_bb = NULL_BLOCK;
3237 /* If the THEN and ELSE block meet in a subsequent block, and the ELSE
3238 has exactly one predecessor and one successor, and the outgoing edge
3239 is not complex, then we have an IF-THEN-ELSE combo. */
3240 else if (single_succ_p (else_bb)
3241 && single_succ (then_bb) == single_succ (else_bb)
3242 && single_pred_p (else_bb)
3243 && ! (single_succ_edge (else_bb)->flags & EDGE_COMPLEX)
3244 && ! (epilogue_completed && tablejump_p (BB_END (else_bb), NULL, NULL)))
3245 join_bb = single_succ (else_bb);
3247 /* Otherwise it is not an IF-THEN or IF-THEN-ELSE combination. */
3251 num_possible_if_blocks++;
3256 "\nIF-THEN%s block found, pass %d, start block %d "
3257 "[insn %d], then %d [%d]",
3258 (else_bb) ? "-ELSE" : "",
3261 BB_HEAD (test_bb) ? (int)INSN_UID (BB_HEAD (test_bb)) : -1,
3263 BB_HEAD (then_bb) ? (int)INSN_UID (BB_HEAD (then_bb)) : -1);
3266 fprintf (dump_file, ", else %d [%d]",
3268 BB_HEAD (else_bb) ? (int)INSN_UID (BB_HEAD (else_bb)) : -1);
3270 fprintf (dump_file, ", join %d [%d]",
3272 BB_HEAD (join_bb) ? (int)INSN_UID (BB_HEAD (join_bb)) : -1);
3274 if (ce_info->num_multiple_test_blocks > 0)
3275 fprintf (dump_file, ", %d %s block%s last test %d [%d]",
3276 ce_info->num_multiple_test_blocks,
3277 (ce_info->and_and_p) ? "&&" : "||",
3278 (ce_info->num_multiple_test_blocks == 1) ? "" : "s",
3279 ce_info->last_test_bb->index,
3280 ((BB_HEAD (ce_info->last_test_bb))
3281 ? (int)INSN_UID (BB_HEAD (ce_info->last_test_bb))
3284 fputc ('\n', dump_file);
3287 /* Make sure IF, THEN, and ELSE, blocks are adjacent. Actually, we get the
3288 first condition for free, since we've already asserted that there's a
3289 fallthru edge from IF to THEN. Likewise for the && and || blocks, since
3290 we checked the FALLTHRU flag, those are already adjacent to the last IF
3292 /* ??? As an enhancement, move the ELSE block. Have to deal with
3293 BLOCK notes, if by no other means than backing out the merge if they
3294 exist. Sticky enough I don't want to think about it now. */
3296 if (else_bb && (next = next->next_bb) != else_bb)
3298 if ((next = next->next_bb) != join_bb && join_bb != EXIT_BLOCK_PTR)
3306 /* Do the real work. */
3308 ce_info->else_bb = else_bb;
3309 ce_info->join_bb = join_bb;
3311 /* If we have && and || tests, try to first handle combining the && and ||
3312 tests into the conditional code, and if that fails, go back and handle
3313 it without the && and ||, which at present handles the && case if there
3314 was no ELSE block. */
3315 if (cond_exec_process_if_block (ce_info, TRUE))
3318 if (ce_info->num_multiple_test_blocks)
3322 if (cond_exec_process_if_block (ce_info, FALSE))
3329 /* Convert a branch over a trap, or a branch
3330 to a trap, into a conditional trap. */
3333 find_cond_trap (basic_block test_bb, edge then_edge, edge else_edge)
3335 basic_block then_bb = then_edge->dest;
3336 basic_block else_bb = else_edge->dest;
3337 basic_block other_bb, trap_bb;
3338 rtx trap, jump, cond, cond_earliest, seq;
3341 /* Locate the block with the trap instruction. */
3342 /* ??? While we look for no successors, we really ought to allow
3343 EH successors. Need to fix merge_if_block for that to work. */
3344 if ((trap = block_has_only_trap (then_bb)) != NULL)
3345 trap_bb = then_bb, other_bb = else_bb;
3346 else if ((trap = block_has_only_trap (else_bb)) != NULL)
3347 trap_bb = else_bb, other_bb = then_bb;
3353 fprintf (dump_file, "\nTRAP-IF block found, start %d, trap %d\n",
3354 test_bb->index, trap_bb->index);
3357 /* If this is not a standard conditional jump, we can't parse it. */
3358 jump = BB_END (test_bb);
3359 cond = noce_get_condition (jump, &cond_earliest, false);
3363 /* If the conditional jump is more than just a conditional jump, then
3364 we can not do if-conversion on this block. */
3365 if (! onlyjump_p (jump))
3368 /* We must be comparing objects whose modes imply the size. */
3369 if (GET_MODE (XEXP (cond, 0)) == BLKmode)
3372 /* Reverse the comparison code, if necessary. */
3373 code = GET_CODE (cond);
3374 if (then_bb == trap_bb)
3376 code = reversed_comparison_code (cond, jump);
3377 if (code == UNKNOWN)
3381 /* Attempt to generate the conditional trap. */
3382 seq = gen_cond_trap (code, copy_rtx (XEXP (cond, 0)),
3383 copy_rtx (XEXP (cond, 1)),
3384 TRAP_CODE (PATTERN (trap)));
3388 /* Emit the new insns before cond_earliest. */
3389 emit_insn_before_setloc (seq, cond_earliest, INSN_LOCATOR (trap));
3391 /* Delete the trap block if possible. */
3392 remove_edge (trap_bb == then_bb ? then_edge : else_edge);
3393 df_set_bb_dirty (test_bb);
3394 df_set_bb_dirty (then_bb);
3395 df_set_bb_dirty (else_bb);
3397 if (EDGE_COUNT (trap_bb->preds) == 0)
3399 delete_basic_block (trap_bb);
3403 /* Wire together the blocks again. */
3404 if (current_ir_type () == IR_RTL_CFGLAYOUT)
3405 single_succ_edge (test_bb)->flags |= EDGE_FALLTHRU;
3410 lab = JUMP_LABEL (jump);
3411 newjump = emit_jump_insn_after (gen_jump (lab), jump);
3412 LABEL_NUSES (lab) += 1;
3413 JUMP_LABEL (newjump) = lab;
3414 emit_barrier_after (newjump);
3418 if (can_merge_blocks_p (test_bb, other_bb))
3420 merge_blocks (test_bb, other_bb);
3424 num_updated_if_blocks++;
3428 /* Subroutine of find_cond_trap: if BB contains only a trap insn,
3432 block_has_only_trap (basic_block bb)
3436 /* We're not the exit block. */
3437 if (bb == EXIT_BLOCK_PTR)
3440 /* The block must have no successors. */
3441 if (EDGE_COUNT (bb->succs) > 0)
3444 /* The only instruction in the THEN block must be the trap. */
3445 trap = first_active_insn (bb);
3446 if (! (trap == BB_END (bb)
3447 && GET_CODE (PATTERN (trap)) == TRAP_IF
3448 && TRAP_CONDITION (PATTERN (trap)) == const_true_rtx))
3454 /* Look for IF-THEN-ELSE cases in which one of THEN or ELSE is
3455 transformable, but not necessarily the other. There need be no
3458 Return TRUE if we were successful at converting the block.
3460 Cases we'd like to look at:
3463 if (test) goto over; // x not live
3471 if (! test) goto label;
3474 if (test) goto E; // x not live
3488 (3) // This one's really only interesting for targets that can do
3489 // multiway branching, e.g. IA-64 BBB bundles. For other targets
3490 // it results in multiple branches on a cache line, which often
3491 // does not sit well with predictors.
3493 if (test1) goto E; // predicted not taken
3509 (A) Don't do (2) if the branch is predicted against the block we're
3510 eliminating. Do it anyway if we can eliminate a branch; this requires
3511 that the sole successor of the eliminated block postdominate the other
3514 (B) With CE, on (3) we can steal from both sides of the if, creating
3523 Again, this is most useful if J postdominates.
3525 (C) CE substitutes for helpful life information.
3527 (D) These heuristics need a lot of work. */
3529 /* Tests for case 1 above. */
3532 find_if_case_1 (basic_block test_bb, edge then_edge, edge else_edge)
3534 basic_block then_bb = then_edge->dest;
3535 basic_block else_bb = else_edge->dest;
3539 /* If we are partitioning hot/cold basic blocks, we don't want to
3540 mess up unconditional or indirect jumps that cross between hot
3543 Basic block partitioning may result in some jumps that appear to
3544 be optimizable (or blocks that appear to be mergeable), but which really
3545 must be left untouched (they are required to make it safely across
3546 partition boundaries). See the comments at the top of
3547 bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */
3549 if ((BB_END (then_bb)
3550 && find_reg_note (BB_END (then_bb), REG_CROSSING_JUMP, NULL_RTX))
3551 || (BB_END (test_bb)
3552 && find_reg_note (BB_END (test_bb), REG_CROSSING_JUMP, NULL_RTX))
3553 || (BB_END (else_bb)
3554 && find_reg_note (BB_END (else_bb), REG_CROSSING_JUMP,
3558 /* THEN has one successor. */
3559 if (!single_succ_p (then_bb))
3562 /* THEN does not fall through, but is not strange either. */
3563 if (single_succ_edge (then_bb)->flags & (EDGE_COMPLEX | EDGE_FALLTHRU))
3566 /* THEN has one predecessor. */
3567 if (!single_pred_p (then_bb))
3570 /* THEN must do something. */
3571 if (forwarder_block_p (then_bb))
3574 num_possible_if_blocks++;
3577 "\nIF-CASE-1 found, start %d, then %d\n",
3578 test_bb->index, then_bb->index);
3580 /* THEN is small. */
3581 if (! cheap_bb_rtx_cost_p (then_bb, COSTS_N_INSNS (BRANCH_COST)))
3584 /* Registers set are dead, or are predicable. */
3585 if (! dead_or_predicable (test_bb, then_bb, else_bb,
3586 single_succ (then_bb), 1))
3589 /* Conversion went ok, including moving the insns and fixing up the
3590 jump. Adjust the CFG to match. */
3592 /* We can avoid creating a new basic block if then_bb is immediately
3593 followed by else_bb, i.e. deleting then_bb allows test_bb to fall
3596 if (then_bb->next_bb == else_bb
3597 && then_bb->prev_bb == test_bb
3598 && else_bb != EXIT_BLOCK_PTR)
3600 redirect_edge_succ (FALLTHRU_EDGE (test_bb), else_bb);
3604 new_bb = redirect_edge_and_branch_force (FALLTHRU_EDGE (test_bb),
3607 df_set_bb_dirty (test_bb);
3608 df_set_bb_dirty (else_bb);
3610 then_bb_index = then_bb->index;
3611 delete_basic_block (then_bb);
3613 /* Make rest of code believe that the newly created block is the THEN_BB
3614 block we removed. */
3617 df_bb_replace (then_bb_index, new_bb);
3618 /* Since the fallthru edge was redirected from test_bb to new_bb,
3619 we need to ensure that new_bb is in the same partition as
3620 test bb (you can not fall through across section boundaries). */
3621 BB_COPY_PARTITION (new_bb, test_bb);
3625 num_updated_if_blocks++;
3630 /* Test for case 2 above. */
3633 find_if_case_2 (basic_block test_bb, edge then_edge, edge else_edge)
3635 basic_block then_bb = then_edge->dest;
3636 basic_block else_bb = else_edge->dest;
3640 /* If we are partitioning hot/cold basic blocks, we don't want to
3641 mess up unconditional or indirect jumps that cross between hot
3644 Basic block partitioning may result in some jumps that appear to
3645 be optimizable (or blocks that appear to be mergeable), but which really
3646 must be left untouched (they are required to make it safely across
3647 partition boundaries). See the comments at the top of
3648 bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */
3650 if ((BB_END (then_bb)
3651 && find_reg_note (BB_END (then_bb), REG_CROSSING_JUMP, NULL_RTX))
3652 || (BB_END (test_bb)
3653 && find_reg_note (BB_END (test_bb), REG_CROSSING_JUMP, NULL_RTX))
3654 || (BB_END (else_bb)
3655 && find_reg_note (BB_END (else_bb), REG_CROSSING_JUMP,
3659 /* ELSE has one successor. */
3660 if (!single_succ_p (else_bb))
3663 else_succ = single_succ_edge (else_bb);
3665 /* ELSE outgoing edge is not complex. */
3666 if (else_succ->flags & EDGE_COMPLEX)
3669 /* ELSE has one predecessor. */
3670 if (!single_pred_p (else_bb))
3673 /* THEN is not EXIT. */
3674 if (then_bb->index < NUM_FIXED_BLOCKS)
3677 /* ELSE is predicted or SUCC(ELSE) postdominates THEN. */
3678 note = find_reg_note (BB_END (test_bb), REG_BR_PROB, NULL_RTX);
3679 if (note && INTVAL (XEXP (note, 0)) >= REG_BR_PROB_BASE / 2)
3681 else if (else_succ->dest->index < NUM_FIXED_BLOCKS
3682 || dominated_by_p (CDI_POST_DOMINATORS, then_bb,
3688 num_possible_if_blocks++;
3691 "\nIF-CASE-2 found, start %d, else %d\n",
3692 test_bb->index, else_bb->index);
3694 /* ELSE is small. */
3695 if (! cheap_bb_rtx_cost_p (else_bb, COSTS_N_INSNS (BRANCH_COST)))
3698 /* Registers set are dead, or are predicable. */
3699 if (! dead_or_predicable (test_bb, else_bb, then_bb, else_succ->dest, 0))
3702 /* Conversion went ok, including moving the insns and fixing up the
3703 jump. Adjust the CFG to match. */
3705 df_set_bb_dirty (test_bb);
3706 df_set_bb_dirty (then_bb);
3707 delete_basic_block (else_bb);
3710 num_updated_if_blocks++;
3712 /* ??? We may now fallthru from one of THEN's successors into a join
3713 block. Rerun cleanup_cfg? Examine things manually? Wait? */
3718 /* A subroutine of dead_or_predicable called through for_each_rtx.
3719 Return 1 if a memory is found. */
3722 find_memory (rtx *px, void *data ATTRIBUTE_UNUSED)
3727 /* Used by the code above to perform the actual rtl transformations.
3728 Return TRUE if successful.
3730 TEST_BB is the block containing the conditional branch. MERGE_BB
3731 is the block containing the code to manipulate. NEW_DEST is the
3732 label TEST_BB should be branching to after the conversion.
3733 REVERSEP is true if the sense of the branch should be reversed. */
3736 dead_or_predicable (basic_block test_bb, basic_block merge_bb,
3737 basic_block other_bb, basic_block new_dest, int reversep)
3739 rtx head, end, jump, earliest = NULL_RTX, old_dest, new_label = NULL_RTX;
3741 jump = BB_END (test_bb);
3743 /* Find the extent of the real code in the merge block. */
3744 head = BB_HEAD (merge_bb);
3745 end = BB_END (merge_bb);
3747 /* If merge_bb ends with a tablejump, predicating/moving insn's
3748 into test_bb and then deleting merge_bb will result in the jumptable
3749 that follows merge_bb being removed along with merge_bb and then we
3750 get an unresolved reference to the jumptable. */
3751 if (tablejump_p (end, NULL, NULL))
3755 head = NEXT_INSN (head);
3760 head = end = NULL_RTX;
3763 head = NEXT_INSN (head);
3770 head = end = NULL_RTX;
3773 end = PREV_INSN (end);
3776 /* Disable handling dead code by conditional execution if the machine needs
3777 to do anything funny with the tests, etc. */
3778 #ifndef IFCVT_MODIFY_TESTS
3779 if (HAVE_conditional_execution)
3781 /* In the conditional execution case, we have things easy. We know
3782 the condition is reversible. We don't have to check life info
3783 because we're going to conditionally execute the code anyway.
3784 All that's left is making sure the insns involved can actually
3789 cond = cond_exec_get_condition (jump);
3793 prob_val = find_reg_note (jump, REG_BR_PROB, NULL_RTX);
3795 prob_val = XEXP (prob_val, 0);
3799 enum rtx_code rev = reversed_comparison_code (cond, jump);
3802 cond = gen_rtx_fmt_ee (rev, GET_MODE (cond), XEXP (cond, 0),
3805 prob_val = GEN_INT (REG_BR_PROB_BASE - INTVAL (prob_val));
3808 if (! cond_exec_process_insns ((ce_if_block_t *)0, head, end, cond,
3817 /* In the non-conditional execution case, we have to verify that there
3818 are no trapping operations, no calls, no references to memory, and
3819 that any registers modified are dead at the branch site. */
3821 rtx insn, cond, prev;
3822 bitmap merge_set, test_live, test_set;
3823 unsigned i, fail = 0;
3826 /* Check for no calls or trapping operations. */
3827 for (insn = head; ; insn = NEXT_INSN (insn))
3833 if (may_trap_p (PATTERN (insn)))
3836 /* ??? Even non-trapping memories such as stack frame
3837 references must be avoided. For stores, we collect
3838 no lifetime info; for reads, we'd have to assert
3839 true_dependence false against every store in the
3841 if (for_each_rtx (&PATTERN (insn), find_memory, NULL))
3848 if (! any_condjump_p (jump))
3851 /* Find the extent of the conditional. */
3852 cond = noce_get_condition (jump, &earliest, false);
3857 MERGE_SET = set of registers set in MERGE_BB
3858 TEST_LIVE = set of registers live at EARLIEST
3859 TEST_SET = set of registers set between EARLIEST and the
3860 end of the block. */
3862 merge_set = BITMAP_ALLOC (®_obstack);
3863 test_live = BITMAP_ALLOC (®_obstack);
3864 test_set = BITMAP_ALLOC (®_obstack);
3866 /* ??? bb->local_set is only valid during calculate_global_regs_live,
3867 so we must recompute usage for MERGE_BB. Not so bad, I suppose,
3868 since we've already asserted that MERGE_BB is small. */
3869 /* If we allocated new pseudos (e.g. in the conditional move
3870 expander called from noce_emit_cmove), we must resize the
3872 if (max_regno < max_reg_num ())
3873 max_regno = max_reg_num ();
3875 FOR_BB_INSNS (merge_bb, insn)
3879 unsigned int uid = INSN_UID (insn);
3880 struct df_ref **def_rec;
3881 for (def_rec = DF_INSN_UID_DEFS (uid); *def_rec; def_rec++)
3883 struct df_ref *def = *def_rec;
3884 bitmap_set_bit (merge_set, DF_REF_REGNO (def));
3889 /* For small register class machines, don't lengthen lifetimes of
3890 hard registers before reload. */
3891 if (SMALL_REGISTER_CLASSES && ! reload_completed)
3893 EXECUTE_IF_SET_IN_BITMAP (merge_set, 0, i, bi)
3895 if (i < FIRST_PSEUDO_REGISTER
3897 && ! global_regs[i])
3902 /* For TEST, we're interested in a range of insns, not a whole block.
3903 Moreover, we're interested in the insns live from OTHER_BB. */
3905 /* The loop below takes the set of live registers
3906 after JUMP, and calculates the live set before EARLIEST. */
3907 bitmap_copy (test_live, df_get_live_in (other_bb));
3908 df_simulate_artificial_refs_at_end (test_bb, test_live);
3909 for (insn = jump; ; insn = prev)
3913 df_simulate_find_defs (insn, test_set);
3914 df_simulate_one_insn_backwards (test_bb, insn, test_live);
3916 prev = PREV_INSN (insn);
3917 if (insn == earliest)
3921 /* We can perform the transformation if
3922 MERGE_SET & (TEST_SET | TEST_LIVE)
3924 TEST_SET & DF_LIVE_IN (merge_bb)
3927 if (bitmap_intersect_p (test_set, merge_set)
3928 || bitmap_intersect_p (test_live, merge_set)
3929 || bitmap_intersect_p (test_set, df_get_live_in (merge_bb)))
3932 BITMAP_FREE (merge_set);
3933 BITMAP_FREE (test_live);
3934 BITMAP_FREE (test_set);
3941 /* We don't want to use normal invert_jump or redirect_jump because
3942 we don't want to delete_insn called. Also, we want to do our own
3943 change group management. */
3945 old_dest = JUMP_LABEL (jump);
3946 if (other_bb != new_dest)
3948 new_label = block_label (new_dest);
3950 ? ! invert_jump_1 (jump, new_label)
3951 : ! redirect_jump_1 (jump, new_label))
3955 if (! apply_change_group ())
3958 if (other_bb != new_dest)
3960 redirect_jump_2 (jump, old_dest, new_label, 0, reversep);
3962 redirect_edge_succ (BRANCH_EDGE (test_bb), new_dest);
3965 gcov_type count, probability;
3966 count = BRANCH_EDGE (test_bb)->count;
3967 BRANCH_EDGE (test_bb)->count = FALLTHRU_EDGE (test_bb)->count;
3968 FALLTHRU_EDGE (test_bb)->count = count;
3969 probability = BRANCH_EDGE (test_bb)->probability;
3970 BRANCH_EDGE (test_bb)->probability
3971 = FALLTHRU_EDGE (test_bb)->probability;
3972 FALLTHRU_EDGE (test_bb)->probability = probability;
3973 update_br_prob_note (test_bb);
3977 /* Move the insns out of MERGE_BB to before the branch. */
3982 if (end == BB_END (merge_bb))
3983 BB_END (merge_bb) = PREV_INSN (head);
3985 /* PR 21767: When moving insns above a conditional branch, REG_EQUAL
3986 notes might become invalid. */
3992 if (! INSN_P (insn))
3994 note = find_reg_note (insn, REG_EQUAL, NULL_RTX);
3997 set = single_set (insn);
3998 if (!set || !function_invariant_p (SET_SRC (set)))
3999 remove_note (insn, note);
4000 } while (insn != end && (insn = NEXT_INSN (insn)));
4002 reorder_insns (head, end, PREV_INSN (earliest));
4005 /* Remove the jump and edge if we can. */
4006 if (other_bb == new_dest)
4009 remove_edge (BRANCH_EDGE (test_bb));
4010 /* ??? Can't merge blocks here, as then_bb is still in use.
4011 At minimum, the merge will get done just before bb-reorder. */
4021 /* Main entry point for all if-conversion. */
4031 df_live_add_problem ();
4032 df_live_set_all_dirty ();
4035 num_possible_if_blocks = 0;
4036 num_updated_if_blocks = 0;
4037 num_true_changes = 0;
4039 loop_optimizer_init (AVOID_CFG_MODIFICATIONS);
4040 mark_loop_exit_edges ();
4041 loop_optimizer_finalize ();
4042 free_dominance_info (CDI_DOMINATORS);
4044 /* Compute postdominators. */
4045 calculate_dominance_info (CDI_POST_DOMINATORS);
4047 df_set_flags (DF_LR_RUN_DCE);
4049 /* Go through each of the basic blocks looking for things to convert. If we
4050 have conditional execution, we make multiple passes to allow us to handle
4051 IF-THEN{-ELSE} blocks within other IF-THEN{-ELSE} blocks. */
4056 /* Only need to do dce on the first pass. */
4057 df_clear_flags (DF_LR_RUN_DCE);
4058 cond_exec_changed_p = FALSE;
4061 #ifdef IFCVT_MULTIPLE_DUMPS
4062 if (dump_file && pass > 1)
4063 fprintf (dump_file, "\n\n========== Pass %d ==========\n", pass);
4069 while (!df_get_bb_dirty (bb)
4070 && (new_bb = find_if_header (bb, pass)) != NULL)
4074 #ifdef IFCVT_MULTIPLE_DUMPS
4075 if (dump_file && cond_exec_changed_p)
4076 print_rtl_with_bb (dump_file, get_insns ());
4079 while (cond_exec_changed_p);
4081 #ifdef IFCVT_MULTIPLE_DUMPS
4083 fprintf (dump_file, "\n\n========== no more changes\n");
4086 free_dominance_info (CDI_POST_DOMINATORS);
4091 clear_aux_for_blocks ();
4093 /* If we allocated new pseudos, we must resize the array for sched1. */
4094 if (max_regno < max_reg_num ())
4095 max_regno = max_reg_num ();
4097 /* Write the final stats. */
4098 if (dump_file && num_possible_if_blocks > 0)
4101 "\n%d possible IF blocks searched.\n",
4102 num_possible_if_blocks);
4104 "%d IF blocks converted.\n",
4105 num_updated_if_blocks);
4107 "%d true changes made.\n\n\n",
4112 df_remove_problem (df_live);
4114 #ifdef ENABLE_CHECKING
4115 verify_flow_info ();
4120 gate_handle_if_conversion (void)
4122 return (optimize > 0)
4123 && dbg_cnt (if_conversion);
4126 /* If-conversion and CFG cleanup. */
4128 rest_of_handle_if_conversion (void)
4130 if (flag_if_conversion)
4133 dump_flow_info (dump_file, dump_flags);
4134 cleanup_cfg (CLEANUP_EXPENSIVE);
4142 struct tree_opt_pass pass_rtl_ifcvt =
4145 gate_handle_if_conversion, /* gate */
4146 rest_of_handle_if_conversion, /* execute */
4149 0, /* static_pass_number */
4150 TV_IFCVT, /* tv_id */
4151 0, /* properties_required */
4152 0, /* properties_provided */
4153 0, /* properties_destroyed */
4154 0, /* todo_flags_start */
4155 TODO_df_finish | TODO_verify_rtl_sharing |
4156 TODO_dump_func, /* todo_flags_finish */
4161 gate_handle_if_after_combine (void)
4163 return optimize > 0 && flag_if_conversion
4164 && dbg_cnt (if_after_combine);
4168 /* Rerun if-conversion, as combine may have simplified things enough
4169 to now meet sequence length restrictions. */
4171 rest_of_handle_if_after_combine (void)
4177 struct tree_opt_pass pass_if_after_combine =
4180 gate_handle_if_after_combine, /* gate */
4181 rest_of_handle_if_after_combine, /* execute */
4184 0, /* static_pass_number */
4185 TV_IFCVT, /* tv_id */
4186 0, /* properties_required */
4187 0, /* properties_provided */
4188 0, /* properties_destroyed */
4189 0, /* todo_flags_start */
4190 TODO_df_finish | TODO_verify_rtl_sharing |
4192 TODO_ggc_collect, /* todo_flags_finish */
4198 gate_handle_if_after_reload (void)
4200 return optimize > 0 && flag_if_conversion2
4201 && dbg_cnt (if_after_reload);
4205 rest_of_handle_if_after_reload (void)
4212 struct tree_opt_pass pass_if_after_reload =
4215 gate_handle_if_after_reload, /* gate */
4216 rest_of_handle_if_after_reload, /* execute */
4219 0, /* static_pass_number */
4220 TV_IFCVT2, /* tv_id */
4221 0, /* properties_required */
4222 0, /* properties_provided */
4223 0, /* properties_destroyed */
4224 0, /* todo_flags_start */
4225 TODO_df_finish | TODO_verify_rtl_sharing |
4227 TODO_ggc_collect, /* todo_flags_finish */