1 /* If-conversion support.
2 Copyright (C) 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2010
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"
38 #include "diagnostic-core.h"
44 #include "tree-pass.h"
50 #ifndef HAVE_conditional_move
51 #define HAVE_conditional_move 0
63 #ifndef MAX_CONDITIONAL_EXECUTE
64 #define MAX_CONDITIONAL_EXECUTE \
65 (BRANCH_COST (optimize_function_for_speed_p (cfun), false) \
69 #define IFCVT_MULTIPLE_DUMPS 1
71 #define NULL_BLOCK ((basic_block) NULL)
73 /* # of IF-THEN or IF-THEN-ELSE blocks we looked at */
74 static int num_possible_if_blocks;
76 /* # of IF-THEN or IF-THEN-ELSE blocks were converted to conditional
78 static int num_updated_if_blocks;
80 /* # of changes made. */
81 static int num_true_changes;
83 /* Whether conditional execution changes were made. */
84 static int cond_exec_changed_p;
86 /* Forward references. */
87 static int count_bb_insns (const_basic_block);
88 static bool cheap_bb_rtx_cost_p (const_basic_block, int);
89 static rtx first_active_insn (basic_block);
90 static rtx last_active_insn (basic_block, int);
91 static rtx find_active_insn_before (basic_block, rtx);
92 static rtx find_active_insn_after (basic_block, rtx);
93 static basic_block block_fallthru (basic_block);
94 static int cond_exec_process_insns (ce_if_block_t *, rtx, rtx, rtx, rtx, int);
95 static rtx cond_exec_get_condition (rtx);
96 static rtx noce_get_condition (rtx, rtx *, bool);
97 static int noce_operand_ok (const_rtx);
98 static void merge_if_block (ce_if_block_t *);
99 static int find_cond_trap (basic_block, edge, edge);
100 static basic_block find_if_header (basic_block, int);
101 static int block_jumps_and_fallthru_p (basic_block, basic_block);
102 static int noce_find_if_block (basic_block, edge, edge, int);
103 static int cond_exec_find_if_block (ce_if_block_t *);
104 static int find_if_case_1 (basic_block, edge, edge);
105 static int find_if_case_2 (basic_block, edge, edge);
106 static int dead_or_predicable (basic_block, basic_block, basic_block,
108 static void noce_emit_move_insn (rtx, rtx);
109 static rtx block_has_only_trap (basic_block);
111 /* Count the number of non-jump active insns in BB. */
114 count_bb_insns (const_basic_block bb)
117 rtx insn = BB_HEAD (bb);
121 if (CALL_P (insn) || NONJUMP_INSN_P (insn))
124 if (insn == BB_END (bb))
126 insn = NEXT_INSN (insn);
132 /* Determine whether the total insn_rtx_cost on non-jump insns in
133 basic block BB is less than MAX_COST. This function returns
134 false if the cost of any instruction could not be estimated. */
137 cheap_bb_rtx_cost_p (const_basic_block bb, int max_cost)
140 rtx insn = BB_HEAD (bb);
141 bool speed = optimize_bb_for_speed_p (bb);
145 if (NONJUMP_INSN_P (insn))
147 int cost = insn_rtx_cost (PATTERN (insn), speed);
151 /* If this instruction is the load or set of a "stack" register,
152 such as a floating point register on x87, then the cost of
153 speculatively executing this insn may need to include
154 the additional cost of popping its result off of the
155 register stack. Unfortunately, correctly recognizing and
156 accounting for this additional overhead is tricky, so for
157 now we simply prohibit such speculative execution. */
160 rtx set = single_set (insn);
161 if (set && STACK_REG_P (SET_DEST (set)))
167 if (count >= max_cost)
170 else if (CALL_P (insn))
173 if (insn == BB_END (bb))
175 insn = NEXT_INSN (insn);
181 /* Return the first non-jump active insn in the basic block. */
184 first_active_insn (basic_block bb)
186 rtx insn = BB_HEAD (bb);
190 if (insn == BB_END (bb))
192 insn = NEXT_INSN (insn);
195 while (NOTE_P (insn) || DEBUG_INSN_P (insn))
197 if (insn == BB_END (bb))
199 insn = NEXT_INSN (insn);
208 /* Return the last non-jump active (non-jump) insn in the basic block. */
211 last_active_insn (basic_block bb, int skip_use_p)
213 rtx insn = BB_END (bb);
214 rtx head = BB_HEAD (bb);
218 || DEBUG_INSN_P (insn)
220 && NONJUMP_INSN_P (insn)
221 && GET_CODE (PATTERN (insn)) == USE))
225 insn = PREV_INSN (insn);
234 /* Return the active insn before INSN inside basic block CURR_BB. */
237 find_active_insn_before (basic_block curr_bb, rtx insn)
239 if (!insn || insn == BB_HEAD (curr_bb))
242 while ((insn = PREV_INSN (insn)) != NULL_RTX)
244 if (NONJUMP_INSN_P (insn) || JUMP_P (insn) || CALL_P (insn))
247 /* No other active insn all the way to the start of the basic block. */
248 if (insn == BB_HEAD (curr_bb))
255 /* Return the active insn after INSN inside basic block CURR_BB. */
258 find_active_insn_after (basic_block curr_bb, rtx insn)
260 if (!insn || insn == BB_END (curr_bb))
263 while ((insn = NEXT_INSN (insn)) != NULL_RTX)
265 if (NONJUMP_INSN_P (insn) || JUMP_P (insn) || CALL_P (insn))
268 /* No other active insn all the way to the end of the basic block. */
269 if (insn == BB_END (curr_bb))
276 /* Return the basic block reached by falling though the basic block BB. */
279 block_fallthru (basic_block bb)
284 FOR_EACH_EDGE (e, ei, bb->succs)
285 if (e->flags & EDGE_FALLTHRU)
288 return (e) ? e->dest : NULL_BLOCK;
291 /* Go through a bunch of insns, converting them to conditional
292 execution format if possible. Return TRUE if all of the non-note
293 insns were processed. */
296 cond_exec_process_insns (ce_if_block_t *ce_info ATTRIBUTE_UNUSED,
297 /* if block information */rtx start,
298 /* first insn to look at */rtx end,
299 /* last insn to look at */rtx test,
300 /* conditional execution test */rtx prob_val,
301 /* probability of branch taken. */int mod_ok)
303 int must_be_last = FALSE;
311 for (insn = start; ; insn = NEXT_INSN (insn))
313 if (NOTE_P (insn) || DEBUG_INSN_P (insn))
316 gcc_assert(NONJUMP_INSN_P (insn) || CALL_P (insn));
318 /* Remove USE insns that get in the way. */
319 if (reload_completed && GET_CODE (PATTERN (insn)) == USE)
321 /* ??? Ug. Actually unlinking the thing is problematic,
322 given what we'd have to coordinate with our callers. */
323 SET_INSN_DELETED (insn);
327 /* Last insn wasn't last? */
331 if (modified_in_p (test, insn))
338 /* Now build the conditional form of the instruction. */
339 pattern = PATTERN (insn);
340 xtest = copy_rtx (test);
342 /* If this is already a COND_EXEC, rewrite the test to be an AND of the
344 if (GET_CODE (pattern) == COND_EXEC)
346 if (GET_MODE (xtest) != GET_MODE (COND_EXEC_TEST (pattern)))
349 xtest = gen_rtx_AND (GET_MODE (xtest), xtest,
350 COND_EXEC_TEST (pattern));
351 pattern = COND_EXEC_CODE (pattern);
354 pattern = gen_rtx_COND_EXEC (VOIDmode, xtest, pattern);
356 /* If the machine needs to modify the insn being conditionally executed,
357 say for example to force a constant integer operand into a temp
358 register, do so here. */
359 #ifdef IFCVT_MODIFY_INSN
360 IFCVT_MODIFY_INSN (ce_info, pattern, insn);
365 validate_change (insn, &PATTERN (insn), pattern, 1);
367 if (CALL_P (insn) && prob_val)
368 validate_change (insn, ®_NOTES (insn),
369 alloc_EXPR_LIST (REG_BR_PROB, prob_val,
370 REG_NOTES (insn)), 1);
380 /* Return the condition for a jump. Do not do any special processing. */
383 cond_exec_get_condition (rtx jump)
387 if (any_condjump_p (jump))
388 test_if = SET_SRC (pc_set (jump));
391 cond = XEXP (test_if, 0);
393 /* If this branches to JUMP_LABEL when the condition is false,
394 reverse the condition. */
395 if (GET_CODE (XEXP (test_if, 2)) == LABEL_REF
396 && XEXP (XEXP (test_if, 2), 0) == JUMP_LABEL (jump))
398 enum rtx_code rev = reversed_comparison_code (cond, jump);
402 cond = gen_rtx_fmt_ee (rev, GET_MODE (cond), XEXP (cond, 0),
409 /* Given a simple IF-THEN or IF-THEN-ELSE block, attempt to convert it
410 to conditional execution. Return TRUE if we were successful at
411 converting the block. */
414 cond_exec_process_if_block (ce_if_block_t * ce_info,
415 /* if block information */int do_multiple_p)
417 basic_block test_bb = ce_info->test_bb; /* last test block */
418 basic_block then_bb = ce_info->then_bb; /* THEN */
419 basic_block else_bb = ce_info->else_bb; /* ELSE or NULL */
420 rtx test_expr; /* expression in IF_THEN_ELSE that is tested */
421 rtx then_start; /* first insn in THEN block */
422 rtx then_end; /* last insn + 1 in THEN block */
423 rtx else_start = NULL_RTX; /* first insn in ELSE block or NULL */
424 rtx else_end = NULL_RTX; /* last insn + 1 in ELSE block */
425 int max; /* max # of insns to convert. */
426 int then_mod_ok; /* whether conditional mods are ok in THEN */
427 rtx true_expr; /* test for else block insns */
428 rtx false_expr; /* test for then block insns */
429 rtx true_prob_val; /* probability of else block */
430 rtx false_prob_val; /* probability of then block */
431 rtx then_last_head = NULL_RTX; /* Last match at the head of THEN */
432 rtx else_last_head = NULL_RTX; /* Last match at the head of ELSE */
433 rtx then_first_tail = NULL_RTX; /* First match at the tail of THEN */
434 rtx else_first_tail = NULL_RTX; /* First match at the tail of ELSE */
435 int then_n_insns, else_n_insns, n_insns;
436 enum rtx_code false_code;
438 /* If test is comprised of && or || elements, and we've failed at handling
439 all of them together, just use the last test if it is the special case of
440 && elements without an ELSE block. */
441 if (!do_multiple_p && ce_info->num_multiple_test_blocks)
443 if (else_bb || ! ce_info->and_and_p)
446 ce_info->test_bb = test_bb = ce_info->last_test_bb;
447 ce_info->num_multiple_test_blocks = 0;
448 ce_info->num_and_and_blocks = 0;
449 ce_info->num_or_or_blocks = 0;
452 /* Find the conditional jump to the ELSE or JOIN part, and isolate
454 test_expr = cond_exec_get_condition (BB_END (test_bb));
458 /* If the conditional jump is more than just a conditional jump,
459 then we can not do conditional execution conversion on this block. */
460 if (! onlyjump_p (BB_END (test_bb)))
463 /* Collect the bounds of where we're to search, skipping any labels, jumps
464 and notes at the beginning and end of the block. Then count the total
465 number of insns and see if it is small enough to convert. */
466 then_start = first_active_insn (then_bb);
467 then_end = last_active_insn (then_bb, TRUE);
468 then_n_insns = ce_info->num_then_insns = count_bb_insns (then_bb);
469 n_insns = then_n_insns;
470 max = MAX_CONDITIONAL_EXECUTE;
477 else_start = first_active_insn (else_bb);
478 else_end = last_active_insn (else_bb, TRUE);
479 else_n_insns = ce_info->num_else_insns = count_bb_insns (else_bb);
480 n_insns += else_n_insns;
482 /* Look for matching sequences at the head and tail of the two blocks,
483 and limit the range of insns to be converted if possible. */
484 n_matching = flow_find_cross_jump (then_bb, else_bb,
485 &then_first_tail, &else_first_tail);
486 if (then_first_tail == BB_HEAD (then_bb))
487 then_start = then_end = NULL_RTX;
488 if (else_first_tail == BB_HEAD (else_bb))
489 else_start = else_end = NULL_RTX;
494 then_end = find_active_insn_before (then_bb, then_first_tail);
496 else_end = find_active_insn_before (else_bb, else_first_tail);
497 n_insns -= 2 * n_matching;
500 if (then_start && else_start)
502 int longest_match = MIN (then_n_insns - n_matching,
503 else_n_insns - n_matching);
505 = flow_find_head_matching_sequence (then_bb, else_bb,
514 /* We won't pass the insns in the head sequence to
515 cond_exec_process_insns, so we need to test them here
516 to make sure that they don't clobber the condition. */
517 for (insn = BB_HEAD (then_bb);
518 insn != NEXT_INSN (then_last_head);
519 insn = NEXT_INSN (insn))
520 if (!LABEL_P (insn) && !NOTE_P (insn)
521 && !DEBUG_INSN_P (insn)
522 && modified_in_p (test_expr, insn))
526 if (then_last_head == then_end)
527 then_start = then_end = NULL_RTX;
528 if (else_last_head == else_end)
529 else_start = else_end = NULL_RTX;
534 then_start = find_active_insn_after (then_bb, then_last_head);
536 else_start = find_active_insn_after (else_bb, else_last_head);
537 n_insns -= 2 * n_matching;
545 /* Map test_expr/test_jump into the appropriate MD tests to use on
546 the conditionally executed code. */
548 true_expr = test_expr;
550 false_code = reversed_comparison_code (true_expr, BB_END (test_bb));
551 if (false_code != UNKNOWN)
552 false_expr = gen_rtx_fmt_ee (false_code, GET_MODE (true_expr),
553 XEXP (true_expr, 0), XEXP (true_expr, 1));
555 false_expr = NULL_RTX;
557 #ifdef IFCVT_MODIFY_TESTS
558 /* If the machine description needs to modify the tests, such as setting a
559 conditional execution register from a comparison, it can do so here. */
560 IFCVT_MODIFY_TESTS (ce_info, true_expr, false_expr);
562 /* See if the conversion failed. */
563 if (!true_expr || !false_expr)
567 true_prob_val = find_reg_note (BB_END (test_bb), REG_BR_PROB, NULL_RTX);
570 true_prob_val = XEXP (true_prob_val, 0);
571 false_prob_val = GEN_INT (REG_BR_PROB_BASE - INTVAL (true_prob_val));
574 false_prob_val = NULL_RTX;
576 /* If we have && or || tests, do them here. These tests are in the adjacent
577 blocks after the first block containing the test. */
578 if (ce_info->num_multiple_test_blocks > 0)
580 basic_block bb = test_bb;
581 basic_block last_test_bb = ce_info->last_test_bb;
590 enum rtx_code f_code;
592 bb = block_fallthru (bb);
593 start = first_active_insn (bb);
594 end = last_active_insn (bb, TRUE);
596 && ! cond_exec_process_insns (ce_info, start, end, false_expr,
597 false_prob_val, FALSE))
600 /* If the conditional jump is more than just a conditional jump, then
601 we can not do conditional execution conversion on this block. */
602 if (! onlyjump_p (BB_END (bb)))
605 /* Find the conditional jump and isolate the test. */
606 t = cond_exec_get_condition (BB_END (bb));
610 f_code = reversed_comparison_code (t, BB_END (bb));
611 if (f_code == UNKNOWN)
614 f = gen_rtx_fmt_ee (f_code, GET_MODE (t), XEXP (t, 0), XEXP (t, 1));
615 if (ce_info->and_and_p)
617 t = gen_rtx_AND (GET_MODE (t), true_expr, t);
618 f = gen_rtx_IOR (GET_MODE (t), false_expr, f);
622 t = gen_rtx_IOR (GET_MODE (t), true_expr, t);
623 f = gen_rtx_AND (GET_MODE (t), false_expr, f);
626 /* If the machine description needs to modify the tests, such as
627 setting a conditional execution register from a comparison, it can
629 #ifdef IFCVT_MODIFY_MULTIPLE_TESTS
630 IFCVT_MODIFY_MULTIPLE_TESTS (ce_info, bb, t, f);
632 /* See if the conversion failed. */
640 while (bb != last_test_bb);
643 /* For IF-THEN-ELSE blocks, we don't allow modifications of the test
644 on then THEN block. */
645 then_mod_ok = (else_bb == NULL_BLOCK);
647 /* Go through the THEN and ELSE blocks converting the insns if possible
648 to conditional execution. */
652 || ! cond_exec_process_insns (ce_info, then_start, then_end,
653 false_expr, false_prob_val,
657 if (else_bb && else_end
658 && ! cond_exec_process_insns (ce_info, else_start, else_end,
659 true_expr, true_prob_val, TRUE))
662 /* If we cannot apply the changes, fail. Do not go through the normal fail
663 processing, since apply_change_group will call cancel_changes. */
664 if (! apply_change_group ())
666 #ifdef IFCVT_MODIFY_CANCEL
667 /* Cancel any machine dependent changes. */
668 IFCVT_MODIFY_CANCEL (ce_info);
673 #ifdef IFCVT_MODIFY_FINAL
674 /* Do any machine dependent final modifications. */
675 IFCVT_MODIFY_FINAL (ce_info);
678 /* Conversion succeeded. */
680 fprintf (dump_file, "%d insn%s converted to conditional execution.\n",
681 n_insns, (n_insns == 1) ? " was" : "s were");
683 /* Merge the blocks! If we had matching sequences, make sure to delete one
684 copy at the appropriate location first: delete the copy in the THEN branch
685 for a tail sequence so that the remaining one is executed last for both
686 branches, and delete the copy in the ELSE branch for a head sequence so
687 that the remaining one is executed first for both branches. */
690 rtx from = then_first_tail;
692 from = find_active_insn_after (then_bb, from);
693 delete_insn_chain (from, BB_END (then_bb), false);
696 delete_insn_chain (first_active_insn (else_bb), else_last_head, false);
698 merge_if_block (ce_info);
699 cond_exec_changed_p = TRUE;
703 #ifdef IFCVT_MODIFY_CANCEL
704 /* Cancel any machine dependent changes. */
705 IFCVT_MODIFY_CANCEL (ce_info);
712 /* Used by noce_process_if_block to communicate with its subroutines.
714 The subroutines know that A and B may be evaluated freely. They
715 know that X is a register. They should insert new instructions
716 before cond_earliest. */
720 /* The basic blocks that make up the IF-THEN-{ELSE-,}JOIN block. */
721 basic_block test_bb, then_bb, else_bb, join_bb;
723 /* The jump that ends TEST_BB. */
726 /* The jump condition. */
729 /* New insns should be inserted before this one. */
732 /* Insns in the THEN and ELSE block. There is always just this
733 one insns in those blocks. The insns are single_set insns.
734 If there was no ELSE block, INSN_B is the last insn before
735 COND_EARLIEST, or NULL_RTX. In the former case, the insn
736 operands are still valid, as if INSN_B was moved down below
740 /* The SET_SRC of INSN_A and INSN_B. */
743 /* The SET_DEST of INSN_A. */
746 /* True if this if block is not canonical. In the canonical form of
747 if blocks, the THEN_BB is the block reached via the fallthru edge
748 from TEST_BB. For the noce transformations, we allow the symmetric
750 bool then_else_reversed;
752 /* Estimated cost of the particular branch instruction. */
756 static rtx noce_emit_store_flag (struct noce_if_info *, rtx, int, int);
757 static int noce_try_move (struct noce_if_info *);
758 static int noce_try_store_flag (struct noce_if_info *);
759 static int noce_try_addcc (struct noce_if_info *);
760 static int noce_try_store_flag_constants (struct noce_if_info *);
761 static int noce_try_store_flag_mask (struct noce_if_info *);
762 static rtx noce_emit_cmove (struct noce_if_info *, rtx, enum rtx_code, rtx,
764 static int noce_try_cmove (struct noce_if_info *);
765 static int noce_try_cmove_arith (struct noce_if_info *);
766 static rtx noce_get_alt_condition (struct noce_if_info *, rtx, rtx *);
767 static int noce_try_minmax (struct noce_if_info *);
768 static int noce_try_abs (struct noce_if_info *);
769 static int noce_try_sign_mask (struct noce_if_info *);
771 /* Helper function for noce_try_store_flag*. */
774 noce_emit_store_flag (struct noce_if_info *if_info, rtx x, int reversep,
777 rtx cond = if_info->cond;
781 cond_complex = (! general_operand (XEXP (cond, 0), VOIDmode)
782 || ! general_operand (XEXP (cond, 1), VOIDmode));
784 /* If earliest == jump, or when the condition is complex, try to
785 build the store_flag insn directly. */
789 rtx set = pc_set (if_info->jump);
790 cond = XEXP (SET_SRC (set), 0);
791 if (GET_CODE (XEXP (SET_SRC (set), 2)) == LABEL_REF
792 && XEXP (XEXP (SET_SRC (set), 2), 0) == JUMP_LABEL (if_info->jump))
793 reversep = !reversep;
794 if (if_info->then_else_reversed)
795 reversep = !reversep;
799 code = reversed_comparison_code (cond, if_info->jump);
801 code = GET_CODE (cond);
803 if ((if_info->cond_earliest == if_info->jump || cond_complex)
804 && (normalize == 0 || STORE_FLAG_VALUE == normalize))
808 tmp = gen_rtx_fmt_ee (code, GET_MODE (x), XEXP (cond, 0),
810 tmp = gen_rtx_SET (VOIDmode, x, tmp);
813 tmp = emit_insn (tmp);
815 if (recog_memoized (tmp) >= 0)
821 if_info->cond_earliest = if_info->jump;
829 /* Don't even try if the comparison operands or the mode of X are weird. */
830 if (cond_complex || !SCALAR_INT_MODE_P (GET_MODE (x)))
833 return emit_store_flag (x, code, XEXP (cond, 0),
834 XEXP (cond, 1), VOIDmode,
835 (code == LTU || code == LEU
836 || code == GEU || code == GTU), normalize);
839 /* Emit instruction to move an rtx, possibly into STRICT_LOW_PART.
840 X is the destination/target and Y is the value to copy. */
843 noce_emit_move_insn (rtx x, rtx y)
845 enum machine_mode outmode;
849 if (GET_CODE (x) != STRICT_LOW_PART)
851 rtx seq, insn, target;
855 /* Check that the SET_SRC is reasonable before calling emit_move_insn,
856 otherwise construct a suitable SET pattern ourselves. */
857 insn = (OBJECT_P (y) || CONSTANT_P (y) || GET_CODE (y) == SUBREG)
858 ? emit_move_insn (x, y)
859 : emit_insn (gen_rtx_SET (VOIDmode, x, y));
863 if (recog_memoized (insn) <= 0)
865 if (GET_CODE (x) == ZERO_EXTRACT)
867 rtx op = XEXP (x, 0);
868 unsigned HOST_WIDE_INT size = INTVAL (XEXP (x, 1));
869 unsigned HOST_WIDE_INT start = INTVAL (XEXP (x, 2));
871 /* store_bit_field expects START to be relative to
872 BYTES_BIG_ENDIAN and adjusts this value for machines with
873 BITS_BIG_ENDIAN != BYTES_BIG_ENDIAN. In order to be able to
874 invoke store_bit_field again it is necessary to have the START
875 value from the first call. */
876 if (BITS_BIG_ENDIAN != BYTES_BIG_ENDIAN)
879 start = BITS_PER_UNIT - start - size;
882 gcc_assert (REG_P (op));
883 start = BITS_PER_WORD - start - size;
887 gcc_assert (start < (MEM_P (op) ? BITS_PER_UNIT : BITS_PER_WORD));
888 store_bit_field (op, size, start, GET_MODE (x), y);
892 switch (GET_RTX_CLASS (GET_CODE (y)))
895 ot = code_to_optab[GET_CODE (y)];
899 target = expand_unop (GET_MODE (y), ot, XEXP (y, 0), x, 0);
900 if (target != NULL_RTX)
903 emit_move_insn (x, target);
912 ot = code_to_optab[GET_CODE (y)];
916 target = expand_binop (GET_MODE (y), ot,
917 XEXP (y, 0), XEXP (y, 1),
919 if (target != NULL_RTX)
922 emit_move_insn (x, target);
939 inner = XEXP (outer, 0);
940 outmode = GET_MODE (outer);
941 bitpos = SUBREG_BYTE (outer) * BITS_PER_UNIT;
942 store_bit_field (inner, GET_MODE_BITSIZE (outmode), bitpos, outmode, y);
945 /* Return sequence of instructions generated by if conversion. This
946 function calls end_sequence() to end the current stream, ensures
947 that are instructions are unshared, recognizable non-jump insns.
948 On failure, this function returns a NULL_RTX. */
951 end_ifcvt_sequence (struct noce_if_info *if_info)
954 rtx seq = get_insns ();
956 set_used_flags (if_info->x);
957 set_used_flags (if_info->cond);
958 unshare_all_rtl_in_chain (seq);
961 /* Make sure that all of the instructions emitted are recognizable,
962 and that we haven't introduced a new jump instruction.
963 As an exercise for the reader, build a general mechanism that
964 allows proper placement of required clobbers. */
965 for (insn = seq; insn; insn = NEXT_INSN (insn))
967 || recog_memoized (insn) == -1)
973 /* Convert "if (a != b) x = a; else x = b" into "x = a" and
974 "if (a == b) x = a; else x = b" into "x = b". */
977 noce_try_move (struct noce_if_info *if_info)
979 rtx cond = if_info->cond;
980 enum rtx_code code = GET_CODE (cond);
983 if (code != NE && code != EQ)
986 /* This optimization isn't valid if either A or B could be a NaN
988 if (HONOR_NANS (GET_MODE (if_info->x))
989 || HONOR_SIGNED_ZEROS (GET_MODE (if_info->x)))
992 /* Check whether the operands of the comparison are A and in
994 if ((rtx_equal_p (if_info->a, XEXP (cond, 0))
995 && rtx_equal_p (if_info->b, XEXP (cond, 1)))
996 || (rtx_equal_p (if_info->a, XEXP (cond, 1))
997 && rtx_equal_p (if_info->b, XEXP (cond, 0))))
999 y = (code == EQ) ? if_info->a : if_info->b;
1001 /* Avoid generating the move if the source is the destination. */
1002 if (! rtx_equal_p (if_info->x, y))
1005 noce_emit_move_insn (if_info->x, y);
1006 seq = end_ifcvt_sequence (if_info);
1010 emit_insn_before_setloc (seq, if_info->jump,
1011 INSN_LOCATOR (if_info->insn_a));
1018 /* Convert "if (test) x = 1; else x = 0".
1020 Only try 0 and STORE_FLAG_VALUE here. Other combinations will be
1021 tried in noce_try_store_flag_constants after noce_try_cmove has had
1022 a go at the conversion. */
1025 noce_try_store_flag (struct noce_if_info *if_info)
1030 if (CONST_INT_P (if_info->b)
1031 && INTVAL (if_info->b) == STORE_FLAG_VALUE
1032 && if_info->a == const0_rtx)
1034 else if (if_info->b == const0_rtx
1035 && CONST_INT_P (if_info->a)
1036 && INTVAL (if_info->a) == STORE_FLAG_VALUE
1037 && (reversed_comparison_code (if_info->cond, if_info->jump)
1045 target = noce_emit_store_flag (if_info, if_info->x, reversep, 0);
1048 if (target != if_info->x)
1049 noce_emit_move_insn (if_info->x, target);
1051 seq = end_ifcvt_sequence (if_info);
1055 emit_insn_before_setloc (seq, if_info->jump,
1056 INSN_LOCATOR (if_info->insn_a));
1066 /* Convert "if (test) x = a; else x = b", for A and B constant. */
1069 noce_try_store_flag_constants (struct noce_if_info *if_info)
1073 HOST_WIDE_INT itrue, ifalse, diff, tmp;
1074 int normalize, can_reverse;
1075 enum machine_mode mode;
1077 if (CONST_INT_P (if_info->a)
1078 && CONST_INT_P (if_info->b))
1080 mode = GET_MODE (if_info->x);
1081 ifalse = INTVAL (if_info->a);
1082 itrue = INTVAL (if_info->b);
1084 /* Make sure we can represent the difference between the two values. */
1085 if ((itrue - ifalse > 0)
1086 != ((ifalse < 0) != (itrue < 0) ? ifalse < 0 : ifalse < itrue))
1089 diff = trunc_int_for_mode (itrue - ifalse, mode);
1091 can_reverse = (reversed_comparison_code (if_info->cond, if_info->jump)
1095 if (diff == STORE_FLAG_VALUE || diff == -STORE_FLAG_VALUE)
1097 else if (ifalse == 0 && exact_log2 (itrue) >= 0
1098 && (STORE_FLAG_VALUE == 1
1099 || if_info->branch_cost >= 2))
1101 else if (itrue == 0 && exact_log2 (ifalse) >= 0 && can_reverse
1102 && (STORE_FLAG_VALUE == 1 || if_info->branch_cost >= 2))
1103 normalize = 1, reversep = 1;
1104 else if (itrue == -1
1105 && (STORE_FLAG_VALUE == -1
1106 || if_info->branch_cost >= 2))
1108 else if (ifalse == -1 && can_reverse
1109 && (STORE_FLAG_VALUE == -1 || if_info->branch_cost >= 2))
1110 normalize = -1, reversep = 1;
1111 else if ((if_info->branch_cost >= 2 && STORE_FLAG_VALUE == -1)
1112 || if_info->branch_cost >= 3)
1119 tmp = itrue; itrue = ifalse; ifalse = tmp;
1120 diff = trunc_int_for_mode (-diff, mode);
1124 target = noce_emit_store_flag (if_info, if_info->x, reversep, normalize);
1131 /* if (test) x = 3; else x = 4;
1132 => x = 3 + (test == 0); */
1133 if (diff == STORE_FLAG_VALUE || diff == -STORE_FLAG_VALUE)
1135 target = expand_simple_binop (mode,
1136 (diff == STORE_FLAG_VALUE
1138 GEN_INT (ifalse), target, if_info->x, 0,
1142 /* if (test) x = 8; else x = 0;
1143 => x = (test != 0) << 3; */
1144 else if (ifalse == 0 && (tmp = exact_log2 (itrue)) >= 0)
1146 target = expand_simple_binop (mode, ASHIFT,
1147 target, GEN_INT (tmp), if_info->x, 0,
1151 /* if (test) x = -1; else x = b;
1152 => x = -(test != 0) | b; */
1153 else if (itrue == -1)
1155 target = expand_simple_binop (mode, IOR,
1156 target, GEN_INT (ifalse), if_info->x, 0,
1160 /* if (test) x = a; else x = b;
1161 => x = (-(test != 0) & (b - a)) + a; */
1164 target = expand_simple_binop (mode, AND,
1165 target, GEN_INT (diff), if_info->x, 0,
1168 target = expand_simple_binop (mode, PLUS,
1169 target, GEN_INT (ifalse),
1170 if_info->x, 0, OPTAB_WIDEN);
1179 if (target != if_info->x)
1180 noce_emit_move_insn (if_info->x, target);
1182 seq = end_ifcvt_sequence (if_info);
1186 emit_insn_before_setloc (seq, if_info->jump,
1187 INSN_LOCATOR (if_info->insn_a));
1194 /* Convert "if (test) foo++" into "foo += (test != 0)", and
1195 similarly for "foo--". */
1198 noce_try_addcc (struct noce_if_info *if_info)
1201 int subtract, normalize;
1203 if (GET_CODE (if_info->a) == PLUS
1204 && rtx_equal_p (XEXP (if_info->a, 0), if_info->b)
1205 && (reversed_comparison_code (if_info->cond, if_info->jump)
1208 rtx cond = if_info->cond;
1209 enum rtx_code code = reversed_comparison_code (cond, if_info->jump);
1211 /* First try to use addcc pattern. */
1212 if (general_operand (XEXP (cond, 0), VOIDmode)
1213 && general_operand (XEXP (cond, 1), VOIDmode))
1216 target = emit_conditional_add (if_info->x, code,
1221 XEXP (if_info->a, 1),
1222 GET_MODE (if_info->x),
1223 (code == LTU || code == GEU
1224 || code == LEU || code == GTU));
1227 if (target != if_info->x)
1228 noce_emit_move_insn (if_info->x, target);
1230 seq = end_ifcvt_sequence (if_info);
1234 emit_insn_before_setloc (seq, if_info->jump,
1235 INSN_LOCATOR (if_info->insn_a));
1241 /* If that fails, construct conditional increment or decrement using
1243 if (if_info->branch_cost >= 2
1244 && (XEXP (if_info->a, 1) == const1_rtx
1245 || XEXP (if_info->a, 1) == constm1_rtx))
1248 if (STORE_FLAG_VALUE == INTVAL (XEXP (if_info->a, 1)))
1249 subtract = 0, normalize = 0;
1250 else if (-STORE_FLAG_VALUE == INTVAL (XEXP (if_info->a, 1)))
1251 subtract = 1, normalize = 0;
1253 subtract = 0, normalize = INTVAL (XEXP (if_info->a, 1));
1256 target = noce_emit_store_flag (if_info,
1257 gen_reg_rtx (GET_MODE (if_info->x)),
1261 target = expand_simple_binop (GET_MODE (if_info->x),
1262 subtract ? MINUS : PLUS,
1263 if_info->b, target, if_info->x,
1267 if (target != if_info->x)
1268 noce_emit_move_insn (if_info->x, target);
1270 seq = end_ifcvt_sequence (if_info);
1274 emit_insn_before_setloc (seq, if_info->jump,
1275 INSN_LOCATOR (if_info->insn_a));
1285 /* Convert "if (test) x = 0;" to "x &= -(test == 0);" */
1288 noce_try_store_flag_mask (struct noce_if_info *if_info)
1294 if ((if_info->branch_cost >= 2
1295 || STORE_FLAG_VALUE == -1)
1296 && ((if_info->a == const0_rtx
1297 && rtx_equal_p (if_info->b, if_info->x))
1298 || ((reversep = (reversed_comparison_code (if_info->cond,
1301 && if_info->b == const0_rtx
1302 && rtx_equal_p (if_info->a, if_info->x))))
1305 target = noce_emit_store_flag (if_info,
1306 gen_reg_rtx (GET_MODE (if_info->x)),
1309 target = expand_simple_binop (GET_MODE (if_info->x), AND,
1311 target, if_info->x, 0,
1316 if (target != if_info->x)
1317 noce_emit_move_insn (if_info->x, target);
1319 seq = end_ifcvt_sequence (if_info);
1323 emit_insn_before_setloc (seq, if_info->jump,
1324 INSN_LOCATOR (if_info->insn_a));
1334 /* Helper function for noce_try_cmove and noce_try_cmove_arith. */
1337 noce_emit_cmove (struct noce_if_info *if_info, rtx x, enum rtx_code code,
1338 rtx cmp_a, rtx cmp_b, rtx vfalse, rtx vtrue)
1340 /* If earliest == jump, try to build the cmove insn directly.
1341 This is helpful when combine has created some complex condition
1342 (like for alpha's cmovlbs) that we can't hope to regenerate
1343 through the normal interface. */
1345 if (if_info->cond_earliest == if_info->jump)
1349 tmp = gen_rtx_fmt_ee (code, GET_MODE (if_info->cond), cmp_a, cmp_b);
1350 tmp = gen_rtx_IF_THEN_ELSE (GET_MODE (x), tmp, vtrue, vfalse);
1351 tmp = gen_rtx_SET (VOIDmode, x, tmp);
1354 tmp = emit_insn (tmp);
1356 if (recog_memoized (tmp) >= 0)
1368 /* Don't even try if the comparison operands are weird. */
1369 if (! general_operand (cmp_a, GET_MODE (cmp_a))
1370 || ! general_operand (cmp_b, GET_MODE (cmp_b)))
1373 #if HAVE_conditional_move
1374 return emit_conditional_move (x, code, cmp_a, cmp_b, VOIDmode,
1375 vtrue, vfalse, GET_MODE (x),
1376 (code == LTU || code == GEU
1377 || code == LEU || code == GTU));
1379 /* We'll never get here, as noce_process_if_block doesn't call the
1380 functions involved. Ifdef code, however, should be discouraged
1381 because it leads to typos in the code not selected. However,
1382 emit_conditional_move won't exist either. */
1387 /* Try only simple constants and registers here. More complex cases
1388 are handled in noce_try_cmove_arith after noce_try_store_flag_arith
1389 has had a go at it. */
1392 noce_try_cmove (struct noce_if_info *if_info)
1397 if ((CONSTANT_P (if_info->a) || register_operand (if_info->a, VOIDmode))
1398 && (CONSTANT_P (if_info->b) || register_operand (if_info->b, VOIDmode)))
1402 code = GET_CODE (if_info->cond);
1403 target = noce_emit_cmove (if_info, if_info->x, code,
1404 XEXP (if_info->cond, 0),
1405 XEXP (if_info->cond, 1),
1406 if_info->a, if_info->b);
1410 if (target != if_info->x)
1411 noce_emit_move_insn (if_info->x, target);
1413 seq = end_ifcvt_sequence (if_info);
1417 emit_insn_before_setloc (seq, if_info->jump,
1418 INSN_LOCATOR (if_info->insn_a));
1431 /* Try more complex cases involving conditional_move. */
1434 noce_try_cmove_arith (struct noce_if_info *if_info)
1446 /* A conditional move from two memory sources is equivalent to a
1447 conditional on their addresses followed by a load. Don't do this
1448 early because it'll screw alias analysis. Note that we've
1449 already checked for no side effects. */
1450 /* ??? FIXME: Magic number 5. */
1451 if (cse_not_expected
1452 && MEM_P (a) && MEM_P (b)
1453 && MEM_ADDR_SPACE (a) == MEM_ADDR_SPACE (b)
1454 && if_info->branch_cost >= 5)
1456 enum machine_mode address_mode
1457 = targetm.addr_space.address_mode (MEM_ADDR_SPACE (a));
1461 x = gen_reg_rtx (address_mode);
1465 /* ??? We could handle this if we knew that a load from A or B could
1466 not fault. This is also true if we've already loaded
1467 from the address along the path from ENTRY. */
1468 else if (may_trap_p (a) || may_trap_p (b))
1471 /* if (test) x = a + b; else x = c - d;
1478 code = GET_CODE (if_info->cond);
1479 insn_a = if_info->insn_a;
1480 insn_b = if_info->insn_b;
1482 /* Total insn_rtx_cost should be smaller than branch cost. Exit
1483 if insn_rtx_cost can't be estimated. */
1487 = insn_rtx_cost (PATTERN (insn_a),
1488 optimize_bb_for_speed_p (BLOCK_FOR_INSN (insn_a)));
1489 if (insn_cost == 0 || insn_cost > COSTS_N_INSNS (if_info->branch_cost))
1498 += insn_rtx_cost (PATTERN (insn_b),
1499 optimize_bb_for_speed_p (BLOCK_FOR_INSN (insn_b)));
1500 if (insn_cost == 0 || insn_cost > COSTS_N_INSNS (if_info->branch_cost))
1504 /* Possibly rearrange operands to make things come out more natural. */
1505 if (reversed_comparison_code (if_info->cond, if_info->jump) != UNKNOWN)
1508 if (rtx_equal_p (b, x))
1510 else if (general_operand (b, GET_MODE (b)))
1515 code = reversed_comparison_code (if_info->cond, if_info->jump);
1516 tmp = a, a = b, b = tmp;
1517 tmp = insn_a, insn_a = insn_b, insn_b = tmp;
1526 /* If either operand is complex, load it into a register first.
1527 The best way to do this is to copy the original insn. In this
1528 way we preserve any clobbers etc that the insn may have had.
1529 This is of course not possible in the IS_MEM case. */
1530 if (! general_operand (a, GET_MODE (a)))
1536 tmp = gen_reg_rtx (GET_MODE (a));
1537 tmp = emit_insn (gen_rtx_SET (VOIDmode, tmp, a));
1540 goto end_seq_and_fail;
1543 a = gen_reg_rtx (GET_MODE (a));
1544 tmp = copy_rtx (insn_a);
1545 set = single_set (tmp);
1547 tmp = emit_insn (PATTERN (tmp));
1549 if (recog_memoized (tmp) < 0)
1550 goto end_seq_and_fail;
1552 if (! general_operand (b, GET_MODE (b)))
1558 tmp = gen_reg_rtx (GET_MODE (b));
1559 tmp = gen_rtx_SET (VOIDmode, tmp, b);
1562 goto end_seq_and_fail;
1565 b = gen_reg_rtx (GET_MODE (b));
1566 tmp = copy_rtx (insn_b);
1567 set = single_set (tmp);
1569 tmp = PATTERN (tmp);
1572 /* If insn to set up A clobbers any registers B depends on, try to
1573 swap insn that sets up A with the one that sets up B. If even
1574 that doesn't help, punt. */
1575 last = get_last_insn ();
1576 if (last && modified_in_p (orig_b, last))
1578 tmp = emit_insn_before (tmp, get_insns ());
1579 if (modified_in_p (orig_a, tmp))
1580 goto end_seq_and_fail;
1583 tmp = emit_insn (tmp);
1585 if (recog_memoized (tmp) < 0)
1586 goto end_seq_and_fail;
1589 target = noce_emit_cmove (if_info, x, code, XEXP (if_info->cond, 0),
1590 XEXP (if_info->cond, 1), a, b);
1593 goto end_seq_and_fail;
1595 /* If we're handling a memory for above, emit the load now. */
1598 tmp = gen_rtx_MEM (GET_MODE (if_info->x), target);
1600 /* Copy over flags as appropriate. */
1601 if (MEM_VOLATILE_P (if_info->a) || MEM_VOLATILE_P (if_info->b))
1602 MEM_VOLATILE_P (tmp) = 1;
1603 if (MEM_IN_STRUCT_P (if_info->a) && MEM_IN_STRUCT_P (if_info->b))
1604 MEM_IN_STRUCT_P (tmp) = 1;
1605 if (MEM_SCALAR_P (if_info->a) && MEM_SCALAR_P (if_info->b))
1606 MEM_SCALAR_P (tmp) = 1;
1607 if (MEM_ALIAS_SET (if_info->a) == MEM_ALIAS_SET (if_info->b))
1608 set_mem_alias_set (tmp, MEM_ALIAS_SET (if_info->a));
1610 MIN (MEM_ALIGN (if_info->a), MEM_ALIGN (if_info->b)));
1612 gcc_assert (MEM_ADDR_SPACE (if_info->a) == MEM_ADDR_SPACE (if_info->b));
1613 set_mem_addr_space (tmp, MEM_ADDR_SPACE (if_info->a));
1615 noce_emit_move_insn (if_info->x, tmp);
1617 else if (target != x)
1618 noce_emit_move_insn (x, target);
1620 tmp = end_ifcvt_sequence (if_info);
1624 emit_insn_before_setloc (tmp, if_info->jump, INSN_LOCATOR (if_info->insn_a));
1632 /* For most cases, the simplified condition we found is the best
1633 choice, but this is not the case for the min/max/abs transforms.
1634 For these we wish to know that it is A or B in the condition. */
1637 noce_get_alt_condition (struct noce_if_info *if_info, rtx target,
1640 rtx cond, set, insn;
1643 /* If target is already mentioned in the known condition, return it. */
1644 if (reg_mentioned_p (target, if_info->cond))
1646 *earliest = if_info->cond_earliest;
1647 return if_info->cond;
1650 set = pc_set (if_info->jump);
1651 cond = XEXP (SET_SRC (set), 0);
1653 = GET_CODE (XEXP (SET_SRC (set), 2)) == LABEL_REF
1654 && XEXP (XEXP (SET_SRC (set), 2), 0) == JUMP_LABEL (if_info->jump);
1655 if (if_info->then_else_reversed)
1658 /* If we're looking for a constant, try to make the conditional
1659 have that constant in it. There are two reasons why it may
1660 not have the constant we want:
1662 1. GCC may have needed to put the constant in a register, because
1663 the target can't compare directly against that constant. For
1664 this case, we look for a SET immediately before the comparison
1665 that puts a constant in that register.
1667 2. GCC may have canonicalized the conditional, for example
1668 replacing "if x < 4" with "if x <= 3". We can undo that (or
1669 make equivalent types of changes) to get the constants we need
1670 if they're off by one in the right direction. */
1672 if (CONST_INT_P (target))
1674 enum rtx_code code = GET_CODE (if_info->cond);
1675 rtx op_a = XEXP (if_info->cond, 0);
1676 rtx op_b = XEXP (if_info->cond, 1);
1679 /* First, look to see if we put a constant in a register. */
1680 prev_insn = prev_nonnote_insn (if_info->cond_earliest);
1682 && BLOCK_FOR_INSN (prev_insn)
1683 == BLOCK_FOR_INSN (if_info->cond_earliest)
1684 && INSN_P (prev_insn)
1685 && GET_CODE (PATTERN (prev_insn)) == SET)
1687 rtx src = find_reg_equal_equiv_note (prev_insn);
1689 src = SET_SRC (PATTERN (prev_insn));
1690 if (CONST_INT_P (src))
1692 if (rtx_equal_p (op_a, SET_DEST (PATTERN (prev_insn))))
1694 else if (rtx_equal_p (op_b, SET_DEST (PATTERN (prev_insn))))
1697 if (CONST_INT_P (op_a))
1702 code = swap_condition (code);
1707 /* Now, look to see if we can get the right constant by
1708 adjusting the conditional. */
1709 if (CONST_INT_P (op_b))
1711 HOST_WIDE_INT desired_val = INTVAL (target);
1712 HOST_WIDE_INT actual_val = INTVAL (op_b);
1717 if (actual_val == desired_val + 1)
1720 op_b = GEN_INT (desired_val);
1724 if (actual_val == desired_val - 1)
1727 op_b = GEN_INT (desired_val);
1731 if (actual_val == desired_val - 1)
1734 op_b = GEN_INT (desired_val);
1738 if (actual_val == desired_val + 1)
1741 op_b = GEN_INT (desired_val);
1749 /* If we made any changes, generate a new conditional that is
1750 equivalent to what we started with, but has the right
1752 if (code != GET_CODE (if_info->cond)
1753 || op_a != XEXP (if_info->cond, 0)
1754 || op_b != XEXP (if_info->cond, 1))
1756 cond = gen_rtx_fmt_ee (code, GET_MODE (cond), op_a, op_b);
1757 *earliest = if_info->cond_earliest;
1762 cond = canonicalize_condition (if_info->jump, cond, reverse,
1763 earliest, target, false, true);
1764 if (! cond || ! reg_mentioned_p (target, cond))
1767 /* We almost certainly searched back to a different place.
1768 Need to re-verify correct lifetimes. */
1770 /* X may not be mentioned in the range (cond_earliest, jump]. */
1771 for (insn = if_info->jump; insn != *earliest; insn = PREV_INSN (insn))
1772 if (INSN_P (insn) && reg_overlap_mentioned_p (if_info->x, PATTERN (insn)))
1775 /* A and B may not be modified in the range [cond_earliest, jump). */
1776 for (insn = *earliest; insn != if_info->jump; insn = NEXT_INSN (insn))
1778 && (modified_in_p (if_info->a, insn)
1779 || modified_in_p (if_info->b, insn)))
1785 /* Convert "if (a < b) x = a; else x = b;" to "x = min(a, b);", etc. */
1788 noce_try_minmax (struct noce_if_info *if_info)
1790 rtx cond, earliest, target, seq;
1791 enum rtx_code code, op;
1794 /* ??? Reject modes with NaNs or signed zeros since we don't know how
1795 they will be resolved with an SMIN/SMAX. It wouldn't be too hard
1796 to get the target to tell us... */
1797 if (HONOR_SIGNED_ZEROS (GET_MODE (if_info->x))
1798 || HONOR_NANS (GET_MODE (if_info->x)))
1801 cond = noce_get_alt_condition (if_info, if_info->a, &earliest);
1805 /* Verify the condition is of the form we expect, and canonicalize
1806 the comparison code. */
1807 code = GET_CODE (cond);
1808 if (rtx_equal_p (XEXP (cond, 0), if_info->a))
1810 if (! rtx_equal_p (XEXP (cond, 1), if_info->b))
1813 else if (rtx_equal_p (XEXP (cond, 1), if_info->a))
1815 if (! rtx_equal_p (XEXP (cond, 0), if_info->b))
1817 code = swap_condition (code);
1822 /* Determine what sort of operation this is. Note that the code is for
1823 a taken branch, so the code->operation mapping appears backwards. */
1856 target = expand_simple_binop (GET_MODE (if_info->x), op,
1857 if_info->a, if_info->b,
1858 if_info->x, unsignedp, OPTAB_WIDEN);
1864 if (target != if_info->x)
1865 noce_emit_move_insn (if_info->x, target);
1867 seq = end_ifcvt_sequence (if_info);
1871 emit_insn_before_setloc (seq, if_info->jump, INSN_LOCATOR (if_info->insn_a));
1872 if_info->cond = cond;
1873 if_info->cond_earliest = earliest;
1878 /* Convert "if (a < 0) x = -a; else x = a;" to "x = abs(a);",
1879 "if (a < 0) x = ~a; else x = a;" to "x = one_cmpl_abs(a);",
1883 noce_try_abs (struct noce_if_info *if_info)
1885 rtx cond, earliest, target, seq, a, b, c;
1887 bool one_cmpl = false;
1889 /* Reject modes with signed zeros. */
1890 if (HONOR_SIGNED_ZEROS (GET_MODE (if_info->x)))
1893 /* Recognize A and B as constituting an ABS or NABS. The canonical
1894 form is a branch around the negation, taken when the object is the
1895 first operand of a comparison against 0 that evaluates to true. */
1898 if (GET_CODE (a) == NEG && rtx_equal_p (XEXP (a, 0), b))
1900 else if (GET_CODE (b) == NEG && rtx_equal_p (XEXP (b, 0), a))
1902 c = a; a = b; b = c;
1905 else if (GET_CODE (a) == NOT && rtx_equal_p (XEXP (a, 0), b))
1910 else if (GET_CODE (b) == NOT && rtx_equal_p (XEXP (b, 0), a))
1912 c = a; a = b; b = c;
1919 cond = noce_get_alt_condition (if_info, b, &earliest);
1923 /* Verify the condition is of the form we expect. */
1924 if (rtx_equal_p (XEXP (cond, 0), b))
1926 else if (rtx_equal_p (XEXP (cond, 1), b))
1934 /* Verify that C is zero. Search one step backward for a
1935 REG_EQUAL note or a simple source if necessary. */
1938 rtx set, insn = prev_nonnote_insn (earliest);
1940 && BLOCK_FOR_INSN (insn) == BLOCK_FOR_INSN (earliest)
1941 && (set = single_set (insn))
1942 && rtx_equal_p (SET_DEST (set), c))
1944 rtx note = find_reg_equal_equiv_note (insn);
1954 && GET_CODE (XEXP (c, 0)) == SYMBOL_REF
1955 && CONSTANT_POOL_ADDRESS_P (XEXP (c, 0)))
1956 c = get_pool_constant (XEXP (c, 0));
1958 /* Work around funny ideas get_condition has wrt canonicalization.
1959 Note that these rtx constants are known to be CONST_INT, and
1960 therefore imply integer comparisons. */
1961 if (c == constm1_rtx && GET_CODE (cond) == GT)
1963 else if (c == const1_rtx && GET_CODE (cond) == LT)
1965 else if (c != CONST0_RTX (GET_MODE (b)))
1968 /* Determine what sort of operation this is. */
1969 switch (GET_CODE (cond))
1988 target = expand_one_cmpl_abs_nojump (GET_MODE (if_info->x), b,
1991 target = expand_abs_nojump (GET_MODE (if_info->x), b, if_info->x, 1);
1993 /* ??? It's a quandary whether cmove would be better here, especially
1994 for integers. Perhaps combine will clean things up. */
1995 if (target && negate)
1998 target = expand_simple_unop (GET_MODE (target), NOT, target,
2001 target = expand_simple_unop (GET_MODE (target), NEG, target,
2011 if (target != if_info->x)
2012 noce_emit_move_insn (if_info->x, target);
2014 seq = end_ifcvt_sequence (if_info);
2018 emit_insn_before_setloc (seq, if_info->jump, INSN_LOCATOR (if_info->insn_a));
2019 if_info->cond = cond;
2020 if_info->cond_earliest = earliest;
2025 /* Convert "if (m < 0) x = b; else x = 0;" to "x = (m >> C) & b;". */
2028 noce_try_sign_mask (struct noce_if_info *if_info)
2030 rtx cond, t, m, c, seq;
2031 enum machine_mode mode;
2033 bool t_unconditional;
2035 cond = if_info->cond;
2036 code = GET_CODE (cond);
2041 if (if_info->a == const0_rtx)
2043 if ((code == LT && c == const0_rtx)
2044 || (code == LE && c == constm1_rtx))
2047 else if (if_info->b == const0_rtx)
2049 if ((code == GE && c == const0_rtx)
2050 || (code == GT && c == constm1_rtx))
2054 if (! t || side_effects_p (t))
2057 /* We currently don't handle different modes. */
2058 mode = GET_MODE (t);
2059 if (GET_MODE (m) != mode)
2062 /* This is only profitable if T is unconditionally executed/evaluated in the
2063 original insn sequence or T is cheap. The former happens if B is the
2064 non-zero (T) value and if INSN_B was taken from TEST_BB, or there was no
2065 INSN_B which can happen for e.g. conditional stores to memory. For the
2066 cost computation use the block TEST_BB where the evaluation will end up
2067 after the transformation. */
2070 && (if_info->insn_b == NULL_RTX
2071 || BLOCK_FOR_INSN (if_info->insn_b) == if_info->test_bb));
2072 if (!(t_unconditional
2073 || (rtx_cost (t, SET, optimize_bb_for_speed_p (if_info->test_bb))
2074 < COSTS_N_INSNS (2))))
2078 /* Use emit_store_flag to generate "m < 0 ? -1 : 0" instead of expanding
2079 "(signed) m >> 31" directly. This benefits targets with specialized
2080 insns to obtain the signmask, but still uses ashr_optab otherwise. */
2081 m = emit_store_flag (gen_reg_rtx (mode), LT, m, const0_rtx, mode, 0, -1);
2082 t = m ? expand_binop (mode, and_optab, m, t, NULL_RTX, 0, OPTAB_DIRECT)
2091 noce_emit_move_insn (if_info->x, t);
2093 seq = end_ifcvt_sequence (if_info);
2097 emit_insn_before_setloc (seq, if_info->jump, INSN_LOCATOR (if_info->insn_a));
2102 /* Optimize away "if (x & C) x |= C" and similar bit manipulation
2106 noce_try_bitop (struct noce_if_info *if_info)
2108 rtx cond, x, a, result, seq;
2109 enum machine_mode mode;
2114 cond = if_info->cond;
2115 code = GET_CODE (cond);
2117 /* Check for no else condition. */
2118 if (! rtx_equal_p (x, if_info->b))
2121 /* Check for a suitable condition. */
2122 if (code != NE && code != EQ)
2124 if (XEXP (cond, 1) != const0_rtx)
2126 cond = XEXP (cond, 0);
2128 /* ??? We could also handle AND here. */
2129 if (GET_CODE (cond) == ZERO_EXTRACT)
2131 if (XEXP (cond, 1) != const1_rtx
2132 || !CONST_INT_P (XEXP (cond, 2))
2133 || ! rtx_equal_p (x, XEXP (cond, 0)))
2135 bitnum = INTVAL (XEXP (cond, 2));
2136 mode = GET_MODE (x);
2137 if (BITS_BIG_ENDIAN)
2138 bitnum = GET_MODE_BITSIZE (mode) - 1 - bitnum;
2139 if (bitnum < 0 || bitnum >= HOST_BITS_PER_WIDE_INT)
2146 if (GET_CODE (a) == IOR || GET_CODE (a) == XOR)
2148 /* Check for "if (X & C) x = x op C". */
2149 if (! rtx_equal_p (x, XEXP (a, 0))
2150 || !CONST_INT_P (XEXP (a, 1))
2151 || (INTVAL (XEXP (a, 1)) & GET_MODE_MASK (mode))
2152 != (unsigned HOST_WIDE_INT) 1 << bitnum)
2155 /* if ((x & C) == 0) x |= C; is transformed to x |= C. */
2156 /* if ((x & C) != 0) x |= C; is transformed to nothing. */
2157 if (GET_CODE (a) == IOR)
2158 result = (code == NE) ? a : NULL_RTX;
2159 else if (code == NE)
2161 /* if ((x & C) == 0) x ^= C; is transformed to x |= C. */
2162 result = gen_int_mode ((HOST_WIDE_INT) 1 << bitnum, mode);
2163 result = simplify_gen_binary (IOR, mode, x, result);
2167 /* if ((x & C) != 0) x ^= C; is transformed to x &= ~C. */
2168 result = gen_int_mode (~((HOST_WIDE_INT) 1 << bitnum), mode);
2169 result = simplify_gen_binary (AND, mode, x, result);
2172 else if (GET_CODE (a) == AND)
2174 /* Check for "if (X & C) x &= ~C". */
2175 if (! rtx_equal_p (x, XEXP (a, 0))
2176 || !CONST_INT_P (XEXP (a, 1))
2177 || (INTVAL (XEXP (a, 1)) & GET_MODE_MASK (mode))
2178 != (~((HOST_WIDE_INT) 1 << bitnum) & GET_MODE_MASK (mode)))
2181 /* if ((x & C) == 0) x &= ~C; is transformed to nothing. */
2182 /* if ((x & C) != 0) x &= ~C; is transformed to x &= ~C. */
2183 result = (code == EQ) ? a : NULL_RTX;
2191 noce_emit_move_insn (x, result);
2192 seq = end_ifcvt_sequence (if_info);
2196 emit_insn_before_setloc (seq, if_info->jump,
2197 INSN_LOCATOR (if_info->insn_a));
2203 /* Similar to get_condition, only the resulting condition must be
2204 valid at JUMP, instead of at EARLIEST.
2206 If THEN_ELSE_REVERSED is true, the fallthrough does not go to the
2207 THEN block of the caller, and we have to reverse the condition. */
2210 noce_get_condition (rtx jump, rtx *earliest, bool then_else_reversed)
2215 if (! any_condjump_p (jump))
2218 set = pc_set (jump);
2220 /* If this branches to JUMP_LABEL when the condition is false,
2221 reverse the condition. */
2222 reverse = (GET_CODE (XEXP (SET_SRC (set), 2)) == LABEL_REF
2223 && XEXP (XEXP (SET_SRC (set), 2), 0) == JUMP_LABEL (jump));
2225 /* We may have to reverse because the caller's if block is not canonical,
2226 i.e. the THEN block isn't the fallthrough block for the TEST block
2227 (see find_if_header). */
2228 if (then_else_reversed)
2231 /* If the condition variable is a register and is MODE_INT, accept it. */
2233 cond = XEXP (SET_SRC (set), 0);
2234 tmp = XEXP (cond, 0);
2235 if (REG_P (tmp) && GET_MODE_CLASS (GET_MODE (tmp)) == MODE_INT)
2240 cond = gen_rtx_fmt_ee (reverse_condition (GET_CODE (cond)),
2241 GET_MODE (cond), tmp, XEXP (cond, 1));
2245 /* Otherwise, fall back on canonicalize_condition to do the dirty
2246 work of manipulating MODE_CC values and COMPARE rtx codes. */
2247 tmp = canonicalize_condition (jump, cond, reverse, earliest,
2248 NULL_RTX, false, true);
2250 /* We don't handle side-effects in the condition, like handling
2251 REG_INC notes and making sure no duplicate conditions are emitted. */
2252 if (tmp != NULL_RTX && side_effects_p (tmp))
2258 /* Return true if OP is ok for if-then-else processing. */
2261 noce_operand_ok (const_rtx op)
2263 /* We special-case memories, so handle any of them with
2264 no address side effects. */
2266 return ! side_effects_p (XEXP (op, 0));
2268 if (side_effects_p (op))
2271 return ! may_trap_p (op);
2274 /* Return true if a write into MEM may trap or fault. */
2277 noce_mem_write_may_trap_or_fault_p (const_rtx mem)
2281 if (MEM_READONLY_P (mem))
2284 if (may_trap_or_fault_p (mem))
2287 addr = XEXP (mem, 0);
2289 /* Call target hook to avoid the effects of -fpic etc.... */
2290 addr = targetm.delegitimize_address (addr);
2293 switch (GET_CODE (addr))
2301 addr = XEXP (addr, 0);
2305 addr = XEXP (addr, 1);
2308 if (CONST_INT_P (XEXP (addr, 1)))
2309 addr = XEXP (addr, 0);
2316 if (SYMBOL_REF_DECL (addr)
2317 && decl_readonly_section (SYMBOL_REF_DECL (addr), 0))
2327 /* Return whether we can use store speculation for MEM. TOP_BB is the
2328 basic block above the conditional block where we are considering
2329 doing the speculative store. We look for whether MEM is set
2330 unconditionally later in the function. */
2333 noce_can_store_speculate_p (basic_block top_bb, const_rtx mem)
2335 basic_block dominator;
2337 for (dominator = get_immediate_dominator (CDI_POST_DOMINATORS, top_bb);
2339 dominator = get_immediate_dominator (CDI_POST_DOMINATORS, dominator))
2343 FOR_BB_INSNS (dominator, insn)
2345 /* If we see something that might be a memory barrier, we
2346 have to stop looking. Even if the MEM is set later in
2347 the function, we still don't want to set it
2348 unconditionally before the barrier. */
2350 && (volatile_insn_p (PATTERN (insn))
2351 || (CALL_P (insn) && (!RTL_CONST_CALL_P (insn)))))
2354 if (memory_modified_in_insn_p (mem, insn))
2356 if (modified_in_p (XEXP (mem, 0), insn))
2365 /* Given a simple IF-THEN-JOIN or IF-THEN-ELSE-JOIN block, attempt to convert
2366 it without using conditional execution. Return TRUE if we were successful
2367 at converting the block. */
2370 noce_process_if_block (struct noce_if_info *if_info)
2372 basic_block test_bb = if_info->test_bb; /* test block */
2373 basic_block then_bb = if_info->then_bb; /* THEN */
2374 basic_block else_bb = if_info->else_bb; /* ELSE or NULL */
2375 basic_block join_bb = if_info->join_bb; /* JOIN */
2376 rtx jump = if_info->jump;
2377 rtx cond = if_info->cond;
2380 rtx orig_x, x, a, b;
2382 /* We're looking for patterns of the form
2384 (1) if (...) x = a; else x = b;
2385 (2) x = b; if (...) x = a;
2386 (3) if (...) x = a; // as if with an initial x = x.
2388 The later patterns require jumps to be more expensive.
2390 ??? For future expansion, look for multiple X in such patterns. */
2392 /* Look for one of the potential sets. */
2393 insn_a = first_active_insn (then_bb);
2395 || insn_a != last_active_insn (then_bb, FALSE)
2396 || (set_a = single_set (insn_a)) == NULL_RTX)
2399 x = SET_DEST (set_a);
2400 a = SET_SRC (set_a);
2402 /* Look for the other potential set. Make sure we've got equivalent
2404 /* ??? This is overconservative. Storing to two different mems is
2405 as easy as conditionally computing the address. Storing to a
2406 single mem merely requires a scratch memory to use as one of the
2407 destination addresses; often the memory immediately below the
2408 stack pointer is available for this. */
2412 insn_b = first_active_insn (else_bb);
2414 || insn_b != last_active_insn (else_bb, FALSE)
2415 || (set_b = single_set (insn_b)) == NULL_RTX
2416 || ! rtx_equal_p (x, SET_DEST (set_b)))
2421 insn_b = prev_nonnote_nondebug_insn (if_info->cond_earliest);
2422 /* We're going to be moving the evaluation of B down from above
2423 COND_EARLIEST to JUMP. Make sure the relevant data is still
2426 || BLOCK_FOR_INSN (insn_b) != BLOCK_FOR_INSN (if_info->cond_earliest)
2427 || !NONJUMP_INSN_P (insn_b)
2428 || (set_b = single_set (insn_b)) == NULL_RTX
2429 || ! rtx_equal_p (x, SET_DEST (set_b))
2430 || ! noce_operand_ok (SET_SRC (set_b))
2431 || reg_overlap_mentioned_p (x, SET_SRC (set_b))
2432 || modified_between_p (SET_SRC (set_b), insn_b, jump)
2433 /* Likewise with X. In particular this can happen when
2434 noce_get_condition looks farther back in the instruction
2435 stream than one might expect. */
2436 || reg_overlap_mentioned_p (x, cond)
2437 || reg_overlap_mentioned_p (x, a)
2438 || modified_between_p (x, insn_b, jump))
2439 insn_b = set_b = NULL_RTX;
2442 /* If x has side effects then only the if-then-else form is safe to
2443 convert. But even in that case we would need to restore any notes
2444 (such as REG_INC) at then end. That can be tricky if
2445 noce_emit_move_insn expands to more than one insn, so disable the
2446 optimization entirely for now if there are side effects. */
2447 if (side_effects_p (x))
2450 b = (set_b ? SET_SRC (set_b) : x);
2452 /* Only operate on register destinations, and even then avoid extending
2453 the lifetime of hard registers on small register class machines. */
2456 || (HARD_REGISTER_P (x)
2457 && targetm.small_register_classes_for_mode_p (GET_MODE (x))))
2459 if (GET_MODE (x) == BLKmode)
2462 if (GET_CODE (x) == ZERO_EXTRACT
2463 && (!CONST_INT_P (XEXP (x, 1))
2464 || !CONST_INT_P (XEXP (x, 2))))
2467 x = gen_reg_rtx (GET_MODE (GET_CODE (x) == STRICT_LOW_PART
2468 ? XEXP (x, 0) : x));
2471 /* Don't operate on sources that may trap or are volatile. */
2472 if (! noce_operand_ok (a) || ! noce_operand_ok (b))
2476 /* Set up the info block for our subroutines. */
2477 if_info->insn_a = insn_a;
2478 if_info->insn_b = insn_b;
2483 /* Try optimizations in some approximation of a useful order. */
2484 /* ??? Should first look to see if X is live incoming at all. If it
2485 isn't, we don't need anything but an unconditional set. */
2487 /* Look and see if A and B are really the same. Avoid creating silly
2488 cmove constructs that no one will fix up later. */
2489 if (rtx_equal_p (a, b))
2491 /* If we have an INSN_B, we don't have to create any new rtl. Just
2492 move the instruction that we already have. If we don't have an
2493 INSN_B, that means that A == X, and we've got a noop move. In
2494 that case don't do anything and let the code below delete INSN_A. */
2495 if (insn_b && else_bb)
2499 if (else_bb && insn_b == BB_END (else_bb))
2500 BB_END (else_bb) = PREV_INSN (insn_b);
2501 reorder_insns (insn_b, insn_b, PREV_INSN (jump));
2503 /* If there was a REG_EQUAL note, delete it since it may have been
2504 true due to this insn being after a jump. */
2505 if ((note = find_reg_note (insn_b, REG_EQUAL, NULL_RTX)) != 0)
2506 remove_note (insn_b, note);
2510 /* If we have "x = b; if (...) x = a;", and x has side-effects, then
2511 x must be executed twice. */
2512 else if (insn_b && side_effects_p (orig_x))
2519 if (!set_b && MEM_P (orig_x))
2521 /* Disallow the "if (...) x = a;" form (implicit "else x = x;")
2522 for optimizations if writing to x may trap or fault,
2523 i.e. it's a memory other than a static var or a stack slot,
2524 is misaligned on strict aligned machines or is read-only. If
2525 x is a read-only memory, then the program is valid only if we
2526 avoid the store into it. If there are stores on both the
2527 THEN and ELSE arms, then we can go ahead with the conversion;
2528 either the program is broken, or the condition is always
2529 false such that the other memory is selected. */
2530 if (noce_mem_write_may_trap_or_fault_p (orig_x))
2533 /* Avoid store speculation: given "if (...) x = a" where x is a
2534 MEM, we only want to do the store if x is always set
2535 somewhere in the function. This avoids cases like
2536 if (pthread_mutex_trylock(mutex))
2538 where we only want global_variable to be changed if the mutex
2539 is held. FIXME: This should ideally be expressed directly in
2541 if (!noce_can_store_speculate_p (test_bb, orig_x))
2545 if (noce_try_move (if_info))
2547 if (noce_try_store_flag (if_info))
2549 if (noce_try_bitop (if_info))
2551 if (noce_try_minmax (if_info))
2553 if (noce_try_abs (if_info))
2555 if (HAVE_conditional_move
2556 && noce_try_cmove (if_info))
2558 if (! targetm.have_conditional_execution ())
2560 if (noce_try_store_flag_constants (if_info))
2562 if (noce_try_addcc (if_info))
2564 if (noce_try_store_flag_mask (if_info))
2566 if (HAVE_conditional_move
2567 && noce_try_cmove_arith (if_info))
2569 if (noce_try_sign_mask (if_info))
2573 if (!else_bb && set_b)
2575 insn_b = set_b = NULL_RTX;
2584 /* If we used a temporary, fix it up now. */
2590 noce_emit_move_insn (orig_x, x);
2592 set_used_flags (orig_x);
2593 unshare_all_rtl_in_chain (seq);
2596 emit_insn_before_setloc (seq, BB_END (test_bb), INSN_LOCATOR (insn_a));
2599 /* The original THEN and ELSE blocks may now be removed. The test block
2600 must now jump to the join block. If the test block and the join block
2601 can be merged, do so. */
2604 delete_basic_block (else_bb);
2608 remove_edge (find_edge (test_bb, join_bb));
2610 remove_edge (find_edge (then_bb, join_bb));
2611 redirect_edge_and_branch_force (single_succ_edge (test_bb), join_bb);
2612 delete_basic_block (then_bb);
2615 if (can_merge_blocks_p (test_bb, join_bb))
2617 merge_blocks (test_bb, join_bb);
2621 num_updated_if_blocks++;
2625 /* Check whether a block is suitable for conditional move conversion.
2626 Every insn must be a simple set of a register to a constant or a
2627 register. For each assignment, store the value in the array VALS,
2628 indexed by register number, then store the register number in
2629 REGS. COND is the condition we will test. */
2632 check_cond_move_block (basic_block bb, rtx *vals, VEC (int, heap) **regs,
2637 /* We can only handle simple jumps at the end of the basic block.
2638 It is almost impossible to update the CFG otherwise. */
2640 if (JUMP_P (insn) && !onlyjump_p (insn))
2643 FOR_BB_INSNS (bb, insn)
2647 if (!NONDEBUG_INSN_P (insn) || JUMP_P (insn))
2649 set = single_set (insn);
2653 dest = SET_DEST (set);
2654 src = SET_SRC (set);
2656 || (HARD_REGISTER_P (dest)
2657 && targetm.small_register_classes_for_mode_p (GET_MODE (dest))))
2660 if (!CONSTANT_P (src) && !register_operand (src, VOIDmode))
2663 if (side_effects_p (src) || side_effects_p (dest))
2666 if (may_trap_p (src) || may_trap_p (dest))
2669 /* Don't try to handle this if the source register was
2670 modified earlier in the block. */
2672 && vals[REGNO (src)] != NULL)
2673 || (GET_CODE (src) == SUBREG && REG_P (SUBREG_REG (src))
2674 && vals[REGNO (SUBREG_REG (src))] != NULL))
2677 /* Don't try to handle this if the destination register was
2678 modified earlier in the block. */
2679 if (vals[REGNO (dest)] != NULL)
2682 /* Don't try to handle this if the condition uses the
2683 destination register. */
2684 if (reg_overlap_mentioned_p (dest, cond))
2687 /* Don't try to handle this if the source register is modified
2688 later in the block. */
2689 if (!CONSTANT_P (src)
2690 && modified_between_p (src, insn, NEXT_INSN (BB_END (bb))))
2693 vals[REGNO (dest)] = src;
2695 VEC_safe_push (int, heap, *regs, REGNO (dest));
2701 /* Given a basic block BB suitable for conditional move conversion,
2702 a condition COND, and arrays THEN_VALS and ELSE_VALS containing the
2703 register values depending on COND, emit the insns in the block as
2704 conditional moves. If ELSE_BLOCK is true, THEN_BB was already
2705 processed. The caller has started a sequence for the conversion.
2706 Return true if successful, false if something goes wrong. */
2709 cond_move_convert_if_block (struct noce_if_info *if_infop,
2710 basic_block bb, rtx cond,
2711 rtx *then_vals, rtx *else_vals,
2715 rtx insn, cond_arg0, cond_arg1;
2717 code = GET_CODE (cond);
2718 cond_arg0 = XEXP (cond, 0);
2719 cond_arg1 = XEXP (cond, 1);
2721 FOR_BB_INSNS (bb, insn)
2723 rtx set, target, dest, t, e;
2726 /* ??? Maybe emit conditional debug insn? */
2727 if (!NONDEBUG_INSN_P (insn) || JUMP_P (insn))
2729 set = single_set (insn);
2730 gcc_assert (set && REG_P (SET_DEST (set)));
2732 dest = SET_DEST (set);
2733 regno = REGNO (dest);
2735 t = then_vals[regno];
2736 e = else_vals[regno];
2740 /* If this register was set in the then block, we already
2741 handled this case there. */
2754 target = noce_emit_cmove (if_infop, dest, code, cond_arg0, cond_arg1,
2760 noce_emit_move_insn (dest, target);
2766 /* Given a simple IF-THEN-JOIN or IF-THEN-ELSE-JOIN block, attempt to convert
2767 it using only conditional moves. Return TRUE if we were successful at
2768 converting the block. */
2771 cond_move_process_if_block (struct noce_if_info *if_info)
2773 basic_block test_bb = if_info->test_bb;
2774 basic_block then_bb = if_info->then_bb;
2775 basic_block else_bb = if_info->else_bb;
2776 basic_block join_bb = if_info->join_bb;
2777 rtx jump = if_info->jump;
2778 rtx cond = if_info->cond;
2780 int max_reg, size, c, reg;
2783 VEC (int, heap) *then_regs = NULL;
2784 VEC (int, heap) *else_regs = NULL;
2787 /* Build a mapping for each block to the value used for each
2789 max_reg = max_reg_num ();
2790 size = (max_reg + 1) * sizeof (rtx);
2791 then_vals = (rtx *) alloca (size);
2792 else_vals = (rtx *) alloca (size);
2793 memset (then_vals, 0, size);
2794 memset (else_vals, 0, size);
2796 /* Make sure the blocks are suitable. */
2797 if (!check_cond_move_block (then_bb, then_vals, &then_regs, cond)
2799 && !check_cond_move_block (else_bb, else_vals, &else_regs, cond)))
2801 VEC_free (int, heap, then_regs);
2802 VEC_free (int, heap, else_regs);
2806 /* Make sure the blocks can be used together. If the same register
2807 is set in both blocks, and is not set to a constant in both
2808 cases, then both blocks must set it to the same register. We
2809 have already verified that if it is set to a register, that the
2810 source register does not change after the assignment. Also count
2811 the number of registers set in only one of the blocks. */
2813 FOR_EACH_VEC_ELT (int, then_regs, i, reg)
2815 if (!then_vals[reg] && !else_vals[reg])
2818 if (!else_vals[reg])
2822 if (!CONSTANT_P (then_vals[reg])
2823 && !CONSTANT_P (else_vals[reg])
2824 && !rtx_equal_p (then_vals[reg], else_vals[reg]))
2826 VEC_free (int, heap, then_regs);
2827 VEC_free (int, heap, else_regs);
2833 /* Finish off c for MAX_CONDITIONAL_EXECUTE. */
2834 FOR_EACH_VEC_ELT (int, else_regs, i, reg)
2835 if (!then_vals[reg])
2838 /* Make sure it is reasonable to convert this block. What matters
2839 is the number of assignments currently made in only one of the
2840 branches, since if we convert we are going to always execute
2842 if (c > MAX_CONDITIONAL_EXECUTE)
2844 VEC_free (int, heap, then_regs);
2845 VEC_free (int, heap, else_regs);
2849 /* Try to emit the conditional moves. First do the then block,
2850 then do anything left in the else blocks. */
2852 if (!cond_move_convert_if_block (if_info, then_bb, cond,
2853 then_vals, else_vals, false)
2855 && !cond_move_convert_if_block (if_info, else_bb, cond,
2856 then_vals, else_vals, true)))
2859 VEC_free (int, heap, then_regs);
2860 VEC_free (int, heap, else_regs);
2863 seq = end_ifcvt_sequence (if_info);
2866 VEC_free (int, heap, then_regs);
2867 VEC_free (int, heap, else_regs);
2871 loc_insn = first_active_insn (then_bb);
2874 loc_insn = first_active_insn (else_bb);
2875 gcc_assert (loc_insn);
2877 emit_insn_before_setloc (seq, jump, INSN_LOCATOR (loc_insn));
2881 delete_basic_block (else_bb);
2885 remove_edge (find_edge (test_bb, join_bb));
2887 remove_edge (find_edge (then_bb, join_bb));
2888 redirect_edge_and_branch_force (single_succ_edge (test_bb), join_bb);
2889 delete_basic_block (then_bb);
2892 if (can_merge_blocks_p (test_bb, join_bb))
2894 merge_blocks (test_bb, join_bb);
2898 num_updated_if_blocks++;
2900 VEC_free (int, heap, then_regs);
2901 VEC_free (int, heap, else_regs);
2906 /* Determine if a given basic block heads a simple IF-THEN-JOIN or an
2907 IF-THEN-ELSE-JOIN block.
2909 If so, we'll try to convert the insns to not require the branch,
2910 using only transformations that do not require conditional execution.
2912 Return TRUE if we were successful at converting the block. */
2915 noce_find_if_block (basic_block test_bb, edge then_edge, edge else_edge,
2918 basic_block then_bb, else_bb, join_bb;
2919 bool then_else_reversed = false;
2922 struct noce_if_info if_info;
2924 /* We only ever should get here before reload. */
2925 gcc_assert (!reload_completed);
2927 /* Recognize an IF-THEN-ELSE-JOIN block. */
2928 if (single_pred_p (then_edge->dest)
2929 && single_succ_p (then_edge->dest)
2930 && single_pred_p (else_edge->dest)
2931 && single_succ_p (else_edge->dest)
2932 && single_succ (then_edge->dest) == single_succ (else_edge->dest))
2934 then_bb = then_edge->dest;
2935 else_bb = else_edge->dest;
2936 join_bb = single_succ (then_bb);
2938 /* Recognize an IF-THEN-JOIN block. */
2939 else if (single_pred_p (then_edge->dest)
2940 && single_succ_p (then_edge->dest)
2941 && single_succ (then_edge->dest) == else_edge->dest)
2943 then_bb = then_edge->dest;
2944 else_bb = NULL_BLOCK;
2945 join_bb = else_edge->dest;
2947 /* Recognize an IF-ELSE-JOIN block. We can have those because the order
2948 of basic blocks in cfglayout mode does not matter, so the fallthrough
2949 edge can go to any basic block (and not just to bb->next_bb, like in
2951 else if (single_pred_p (else_edge->dest)
2952 && single_succ_p (else_edge->dest)
2953 && single_succ (else_edge->dest) == then_edge->dest)
2955 /* The noce transformations do not apply to IF-ELSE-JOIN blocks.
2956 To make this work, we have to invert the THEN and ELSE blocks
2957 and reverse the jump condition. */
2958 then_bb = else_edge->dest;
2959 else_bb = NULL_BLOCK;
2960 join_bb = single_succ (then_bb);
2961 then_else_reversed = true;
2964 /* Not a form we can handle. */
2967 /* The edges of the THEN and ELSE blocks cannot have complex edges. */
2968 if (single_succ_edge (then_bb)->flags & EDGE_COMPLEX)
2971 && single_succ_edge (else_bb)->flags & EDGE_COMPLEX)
2974 num_possible_if_blocks++;
2979 "\nIF-THEN%s-JOIN block found, pass %d, test %d, then %d",
2980 (else_bb) ? "-ELSE" : "",
2981 pass, test_bb->index, then_bb->index);
2984 fprintf (dump_file, ", else %d", else_bb->index);
2986 fprintf (dump_file, ", join %d\n", join_bb->index);
2989 /* If the conditional jump is more than just a conditional
2990 jump, then we can not do if-conversion on this block. */
2991 jump = BB_END (test_bb);
2992 if (! onlyjump_p (jump))
2995 /* If this is not a standard conditional jump, we can't parse it. */
2996 cond = noce_get_condition (jump, &cond_earliest, then_else_reversed);
3000 /* We must be comparing objects whose modes imply the size. */
3001 if (GET_MODE (XEXP (cond, 0)) == BLKmode)
3004 /* Initialize an IF_INFO struct to pass around. */
3005 memset (&if_info, 0, sizeof if_info);
3006 if_info.test_bb = test_bb;
3007 if_info.then_bb = then_bb;
3008 if_info.else_bb = else_bb;
3009 if_info.join_bb = join_bb;
3010 if_info.cond = cond;
3011 if_info.cond_earliest = cond_earliest;
3012 if_info.jump = jump;
3013 if_info.then_else_reversed = then_else_reversed;
3014 if_info.branch_cost = BRANCH_COST (optimize_bb_for_speed_p (test_bb),
3015 predictable_edge_p (then_edge));
3017 /* Do the real work. */
3019 if (noce_process_if_block (&if_info))
3022 if (HAVE_conditional_move
3023 && cond_move_process_if_block (&if_info))
3030 /* Merge the blocks and mark for local life update. */
3033 merge_if_block (struct ce_if_block * ce_info)
3035 basic_block test_bb = ce_info->test_bb; /* last test block */
3036 basic_block then_bb = ce_info->then_bb; /* THEN */
3037 basic_block else_bb = ce_info->else_bb; /* ELSE or NULL */
3038 basic_block join_bb = ce_info->join_bb; /* join block */
3039 basic_block combo_bb;
3041 /* All block merging is done into the lower block numbers. */
3044 df_set_bb_dirty (test_bb);
3046 /* Merge any basic blocks to handle && and || subtests. Each of
3047 the blocks are on the fallthru path from the predecessor block. */
3048 if (ce_info->num_multiple_test_blocks > 0)
3050 basic_block bb = test_bb;
3051 basic_block last_test_bb = ce_info->last_test_bb;
3052 basic_block fallthru = block_fallthru (bb);
3057 fallthru = block_fallthru (bb);
3058 merge_blocks (combo_bb, bb);
3061 while (bb != last_test_bb);
3064 /* Merge TEST block into THEN block. Normally the THEN block won't have a
3065 label, but it might if there were || tests. That label's count should be
3066 zero, and it normally should be removed. */
3070 merge_blocks (combo_bb, then_bb);
3074 /* The ELSE block, if it existed, had a label. That label count
3075 will almost always be zero, but odd things can happen when labels
3076 get their addresses taken. */
3079 merge_blocks (combo_bb, else_bb);
3083 /* If there was no join block reported, that means it was not adjacent
3084 to the others, and so we cannot merge them. */
3088 rtx last = BB_END (combo_bb);
3090 /* The outgoing edge for the current COMBO block should already
3091 be correct. Verify this. */
3092 if (EDGE_COUNT (combo_bb->succs) == 0)
3093 gcc_assert (find_reg_note (last, REG_NORETURN, NULL)
3094 || (NONJUMP_INSN_P (last)
3095 && GET_CODE (PATTERN (last)) == TRAP_IF
3096 && (TRAP_CONDITION (PATTERN (last))
3097 == const_true_rtx)));
3100 /* There should still be something at the end of the THEN or ELSE
3101 blocks taking us to our final destination. */
3102 gcc_assert (JUMP_P (last)
3103 || (EDGE_SUCC (combo_bb, 0)->dest == EXIT_BLOCK_PTR
3105 && SIBLING_CALL_P (last))
3106 || ((EDGE_SUCC (combo_bb, 0)->flags & EDGE_EH)
3107 && can_throw_internal (last)));
3110 /* The JOIN block may have had quite a number of other predecessors too.
3111 Since we've already merged the TEST, THEN and ELSE blocks, we should
3112 have only one remaining edge from our if-then-else diamond. If there
3113 is more than one remaining edge, it must come from elsewhere. There
3114 may be zero incoming edges if the THEN block didn't actually join
3115 back up (as with a call to a non-return function). */
3116 else if (EDGE_COUNT (join_bb->preds) < 2
3117 && join_bb != EXIT_BLOCK_PTR)
3119 /* We can merge the JOIN cleanly and update the dataflow try
3120 again on this pass.*/
3121 merge_blocks (combo_bb, join_bb);
3126 /* We cannot merge the JOIN. */
3128 /* The outgoing edge for the current COMBO block should already
3129 be correct. Verify this. */
3130 gcc_assert (single_succ_p (combo_bb)
3131 && single_succ (combo_bb) == join_bb);
3133 /* Remove the jump and cruft from the end of the COMBO block. */
3134 if (join_bb != EXIT_BLOCK_PTR)
3135 tidy_fallthru_edge (single_succ_edge (combo_bb));
3138 num_updated_if_blocks++;
3141 /* Find a block ending in a simple IF condition and try to transform it
3142 in some way. When converting a multi-block condition, put the new code
3143 in the first such block and delete the rest. Return a pointer to this
3144 first block if some transformation was done. Return NULL otherwise. */
3147 find_if_header (basic_block test_bb, int pass)
3149 ce_if_block_t ce_info;
3153 /* The kind of block we're looking for has exactly two successors. */
3154 if (EDGE_COUNT (test_bb->succs) != 2)
3157 then_edge = EDGE_SUCC (test_bb, 0);
3158 else_edge = EDGE_SUCC (test_bb, 1);
3160 if (df_get_bb_dirty (then_edge->dest))
3162 if (df_get_bb_dirty (else_edge->dest))
3165 /* Neither edge should be abnormal. */
3166 if ((then_edge->flags & EDGE_COMPLEX)
3167 || (else_edge->flags & EDGE_COMPLEX))
3170 /* Nor exit the loop. */
3171 if ((then_edge->flags & EDGE_LOOP_EXIT)
3172 || (else_edge->flags & EDGE_LOOP_EXIT))
3175 /* The THEN edge is canonically the one that falls through. */
3176 if (then_edge->flags & EDGE_FALLTHRU)
3178 else if (else_edge->flags & EDGE_FALLTHRU)
3181 else_edge = then_edge;
3185 /* Otherwise this must be a multiway branch of some sort. */
3188 memset (&ce_info, 0, sizeof (ce_info));
3189 ce_info.test_bb = test_bb;
3190 ce_info.then_bb = then_edge->dest;
3191 ce_info.else_bb = else_edge->dest;
3192 ce_info.pass = pass;
3194 #ifdef IFCVT_INIT_EXTRA_FIELDS
3195 IFCVT_INIT_EXTRA_FIELDS (&ce_info);
3198 if (!reload_completed
3199 && noce_find_if_block (test_bb, then_edge, else_edge, pass))
3202 if (reload_completed
3203 && targetm.have_conditional_execution ()
3204 && cond_exec_find_if_block (&ce_info))
3208 && optab_handler (ctrap_optab, word_mode) != CODE_FOR_nothing
3209 && find_cond_trap (test_bb, then_edge, else_edge))
3212 if (dom_info_state (CDI_POST_DOMINATORS) >= DOM_NO_FAST_QUERY
3213 && (reload_completed || !targetm.have_conditional_execution ()))
3215 if (find_if_case_1 (test_bb, then_edge, else_edge))
3217 if (find_if_case_2 (test_bb, then_edge, else_edge))
3225 fprintf (dump_file, "Conversion succeeded on pass %d.\n", pass);
3226 /* Set this so we continue looking. */
3227 cond_exec_changed_p = TRUE;
3228 return ce_info.test_bb;
3231 /* Return true if a block has two edges, one of which falls through to the next
3232 block, and the other jumps to a specific block, so that we can tell if the
3233 block is part of an && test or an || test. Returns either -1 or the number
3234 of non-note, non-jump, non-USE/CLOBBER insns in the block. */
3237 block_jumps_and_fallthru_p (basic_block cur_bb, basic_block target_bb)
3240 int fallthru_p = FALSE;
3247 if (!cur_bb || !target_bb)
3250 /* If no edges, obviously it doesn't jump or fallthru. */
3251 if (EDGE_COUNT (cur_bb->succs) == 0)
3254 FOR_EACH_EDGE (cur_edge, ei, cur_bb->succs)
3256 if (cur_edge->flags & EDGE_COMPLEX)
3257 /* Anything complex isn't what we want. */
3260 else if (cur_edge->flags & EDGE_FALLTHRU)
3263 else if (cur_edge->dest == target_bb)
3270 if ((jump_p & fallthru_p) == 0)
3273 /* Don't allow calls in the block, since this is used to group && and ||
3274 together for conditional execution support. ??? we should support
3275 conditional execution support across calls for IA-64 some day, but
3276 for now it makes the code simpler. */
3277 end = BB_END (cur_bb);
3278 insn = BB_HEAD (cur_bb);
3280 while (insn != NULL_RTX)
3287 && !DEBUG_INSN_P (insn)
3288 && GET_CODE (PATTERN (insn)) != USE
3289 && GET_CODE (PATTERN (insn)) != CLOBBER)
3295 insn = NEXT_INSN (insn);
3301 /* Determine if a given basic block heads a simple IF-THEN or IF-THEN-ELSE
3302 block. If so, we'll try to convert the insns to not require the branch.
3303 Return TRUE if we were successful at converting the block. */
3306 cond_exec_find_if_block (struct ce_if_block * ce_info)
3308 basic_block test_bb = ce_info->test_bb;
3309 basic_block then_bb = ce_info->then_bb;
3310 basic_block else_bb = ce_info->else_bb;
3311 basic_block join_bb = NULL_BLOCK;
3316 ce_info->last_test_bb = test_bb;
3318 /* We only ever should get here after reload,
3319 and if we have conditional execution. */
3320 gcc_assert (reload_completed && targetm.have_conditional_execution ());
3322 /* Discover if any fall through predecessors of the current test basic block
3323 were && tests (which jump to the else block) or || tests (which jump to
3325 if (single_pred_p (test_bb)
3326 && single_pred_edge (test_bb)->flags == EDGE_FALLTHRU)
3328 basic_block bb = single_pred (test_bb);
3329 basic_block target_bb;
3330 int max_insns = MAX_CONDITIONAL_EXECUTE;
3333 /* Determine if the preceding block is an && or || block. */
3334 if ((n_insns = block_jumps_and_fallthru_p (bb, else_bb)) >= 0)
3336 ce_info->and_and_p = TRUE;
3337 target_bb = else_bb;
3339 else if ((n_insns = block_jumps_and_fallthru_p (bb, then_bb)) >= 0)
3341 ce_info->and_and_p = FALSE;
3342 target_bb = then_bb;
3345 target_bb = NULL_BLOCK;
3347 if (target_bb && n_insns <= max_insns)
3349 int total_insns = 0;
3352 ce_info->last_test_bb = test_bb;
3354 /* Found at least one && or || block, look for more. */
3357 ce_info->test_bb = test_bb = bb;
3358 total_insns += n_insns;
3361 if (!single_pred_p (bb))
3364 bb = single_pred (bb);
3365 n_insns = block_jumps_and_fallthru_p (bb, target_bb);
3367 while (n_insns >= 0 && (total_insns + n_insns) <= max_insns);
3369 ce_info->num_multiple_test_blocks = blocks;
3370 ce_info->num_multiple_test_insns = total_insns;
3372 if (ce_info->and_and_p)
3373 ce_info->num_and_and_blocks = blocks;
3375 ce_info->num_or_or_blocks = blocks;
3379 /* The THEN block of an IF-THEN combo must have exactly one predecessor,
3380 other than any || blocks which jump to the THEN block. */
3381 if ((EDGE_COUNT (then_bb->preds) - ce_info->num_or_or_blocks) != 1)
3384 /* The edges of the THEN and ELSE blocks cannot have complex edges. */
3385 FOR_EACH_EDGE (cur_edge, ei, then_bb->preds)
3387 if (cur_edge->flags & EDGE_COMPLEX)
3391 FOR_EACH_EDGE (cur_edge, ei, else_bb->preds)
3393 if (cur_edge->flags & EDGE_COMPLEX)
3397 /* The THEN block of an IF-THEN combo must have zero or one successors. */
3398 if (EDGE_COUNT (then_bb->succs) > 0
3399 && (!single_succ_p (then_bb)
3400 || (single_succ_edge (then_bb)->flags & EDGE_COMPLEX)
3401 || (epilogue_completed
3402 && tablejump_p (BB_END (then_bb), NULL, NULL))))
3405 /* If the THEN block has no successors, conditional execution can still
3406 make a conditional call. Don't do this unless the ELSE block has
3407 only one incoming edge -- the CFG manipulation is too ugly otherwise.
3408 Check for the last insn of the THEN block being an indirect jump, which
3409 is listed as not having any successors, but confuses the rest of the CE
3410 code processing. ??? we should fix this in the future. */
3411 if (EDGE_COUNT (then_bb->succs) == 0)
3413 if (single_pred_p (else_bb))
3415 rtx last_insn = BB_END (then_bb);
3418 && NOTE_P (last_insn)
3419 && last_insn != BB_HEAD (then_bb))
3420 last_insn = PREV_INSN (last_insn);
3423 && JUMP_P (last_insn)
3424 && ! simplejump_p (last_insn))
3428 else_bb = NULL_BLOCK;
3434 /* If the THEN block's successor is the other edge out of the TEST block,
3435 then we have an IF-THEN combo without an ELSE. */
3436 else if (single_succ (then_bb) == else_bb)
3439 else_bb = NULL_BLOCK;
3442 /* If the THEN and ELSE block meet in a subsequent block, and the ELSE
3443 has exactly one predecessor and one successor, and the outgoing edge
3444 is not complex, then we have an IF-THEN-ELSE combo. */
3445 else if (single_succ_p (else_bb)
3446 && single_succ (then_bb) == single_succ (else_bb)
3447 && single_pred_p (else_bb)
3448 && !(single_succ_edge (else_bb)->flags & EDGE_COMPLEX)
3449 && !(epilogue_completed
3450 && tablejump_p (BB_END (else_bb), NULL, NULL)))
3451 join_bb = single_succ (else_bb);
3453 /* Otherwise it is not an IF-THEN or IF-THEN-ELSE combination. */
3457 num_possible_if_blocks++;
3462 "\nIF-THEN%s block found, pass %d, start block %d "
3463 "[insn %d], then %d [%d]",
3464 (else_bb) ? "-ELSE" : "",
3467 BB_HEAD (test_bb) ? (int)INSN_UID (BB_HEAD (test_bb)) : -1,
3469 BB_HEAD (then_bb) ? (int)INSN_UID (BB_HEAD (then_bb)) : -1);
3472 fprintf (dump_file, ", else %d [%d]",
3474 BB_HEAD (else_bb) ? (int)INSN_UID (BB_HEAD (else_bb)) : -1);
3476 fprintf (dump_file, ", join %d [%d]",
3478 BB_HEAD (join_bb) ? (int)INSN_UID (BB_HEAD (join_bb)) : -1);
3480 if (ce_info->num_multiple_test_blocks > 0)
3481 fprintf (dump_file, ", %d %s block%s last test %d [%d]",
3482 ce_info->num_multiple_test_blocks,
3483 (ce_info->and_and_p) ? "&&" : "||",
3484 (ce_info->num_multiple_test_blocks == 1) ? "" : "s",
3485 ce_info->last_test_bb->index,
3486 ((BB_HEAD (ce_info->last_test_bb))
3487 ? (int)INSN_UID (BB_HEAD (ce_info->last_test_bb))
3490 fputc ('\n', dump_file);
3493 /* Make sure IF, THEN, and ELSE, blocks are adjacent. Actually, we get the
3494 first condition for free, since we've already asserted that there's a
3495 fallthru edge from IF to THEN. Likewise for the && and || blocks, since
3496 we checked the FALLTHRU flag, those are already adjacent to the last IF
3498 /* ??? As an enhancement, move the ELSE block. Have to deal with
3499 BLOCK notes, if by no other means than backing out the merge if they
3500 exist. Sticky enough I don't want to think about it now. */
3502 if (else_bb && (next = next->next_bb) != else_bb)
3504 if ((next = next->next_bb) != join_bb && join_bb != EXIT_BLOCK_PTR)
3512 /* Do the real work. */
3514 ce_info->else_bb = else_bb;
3515 ce_info->join_bb = join_bb;
3517 /* If we have && and || tests, try to first handle combining the && and ||
3518 tests into the conditional code, and if that fails, go back and handle
3519 it without the && and ||, which at present handles the && case if there
3520 was no ELSE block. */
3521 if (cond_exec_process_if_block (ce_info, TRUE))
3524 if (ce_info->num_multiple_test_blocks)
3528 if (cond_exec_process_if_block (ce_info, FALSE))
3535 /* Convert a branch over a trap, or a branch
3536 to a trap, into a conditional trap. */
3539 find_cond_trap (basic_block test_bb, edge then_edge, edge else_edge)
3541 basic_block then_bb = then_edge->dest;
3542 basic_block else_bb = else_edge->dest;
3543 basic_block other_bb, trap_bb;
3544 rtx trap, jump, cond, cond_earliest, seq;
3547 /* Locate the block with the trap instruction. */
3548 /* ??? While we look for no successors, we really ought to allow
3549 EH successors. Need to fix merge_if_block for that to work. */
3550 if ((trap = block_has_only_trap (then_bb)) != NULL)
3551 trap_bb = then_bb, other_bb = else_bb;
3552 else if ((trap = block_has_only_trap (else_bb)) != NULL)
3553 trap_bb = else_bb, other_bb = then_bb;
3559 fprintf (dump_file, "\nTRAP-IF block found, start %d, trap %d\n",
3560 test_bb->index, trap_bb->index);
3563 /* If this is not a standard conditional jump, we can't parse it. */
3564 jump = BB_END (test_bb);
3565 cond = noce_get_condition (jump, &cond_earliest, false);
3569 /* If the conditional jump is more than just a conditional jump, then
3570 we can not do if-conversion on this block. */
3571 if (! onlyjump_p (jump))
3574 /* We must be comparing objects whose modes imply the size. */
3575 if (GET_MODE (XEXP (cond, 0)) == BLKmode)
3578 /* Reverse the comparison code, if necessary. */
3579 code = GET_CODE (cond);
3580 if (then_bb == trap_bb)
3582 code = reversed_comparison_code (cond, jump);
3583 if (code == UNKNOWN)
3587 /* Attempt to generate the conditional trap. */
3588 seq = gen_cond_trap (code, copy_rtx (XEXP (cond, 0)),
3589 copy_rtx (XEXP (cond, 1)),
3590 TRAP_CODE (PATTERN (trap)));
3594 /* Emit the new insns before cond_earliest. */
3595 emit_insn_before_setloc (seq, cond_earliest, INSN_LOCATOR (trap));
3597 /* Delete the trap block if possible. */
3598 remove_edge (trap_bb == then_bb ? then_edge : else_edge);
3599 df_set_bb_dirty (test_bb);
3600 df_set_bb_dirty (then_bb);
3601 df_set_bb_dirty (else_bb);
3603 if (EDGE_COUNT (trap_bb->preds) == 0)
3605 delete_basic_block (trap_bb);
3609 /* Wire together the blocks again. */
3610 if (current_ir_type () == IR_RTL_CFGLAYOUT)
3611 single_succ_edge (test_bb)->flags |= EDGE_FALLTHRU;
3616 lab = JUMP_LABEL (jump);
3617 newjump = emit_jump_insn_after (gen_jump (lab), jump);
3618 LABEL_NUSES (lab) += 1;
3619 JUMP_LABEL (newjump) = lab;
3620 emit_barrier_after (newjump);
3624 if (can_merge_blocks_p (test_bb, other_bb))
3626 merge_blocks (test_bb, other_bb);
3630 num_updated_if_blocks++;
3634 /* Subroutine of find_cond_trap: if BB contains only a trap insn,
3638 block_has_only_trap (basic_block bb)
3642 /* We're not the exit block. */
3643 if (bb == EXIT_BLOCK_PTR)
3646 /* The block must have no successors. */
3647 if (EDGE_COUNT (bb->succs) > 0)
3650 /* The only instruction in the THEN block must be the trap. */
3651 trap = first_active_insn (bb);
3652 if (! (trap == BB_END (bb)
3653 && GET_CODE (PATTERN (trap)) == TRAP_IF
3654 && TRAP_CONDITION (PATTERN (trap)) == const_true_rtx))
3660 /* Look for IF-THEN-ELSE cases in which one of THEN or ELSE is
3661 transformable, but not necessarily the other. There need be no
3664 Return TRUE if we were successful at converting the block.
3666 Cases we'd like to look at:
3669 if (test) goto over; // x not live
3677 if (! test) goto label;
3680 if (test) goto E; // x not live
3694 (3) // This one's really only interesting for targets that can do
3695 // multiway branching, e.g. IA-64 BBB bundles. For other targets
3696 // it results in multiple branches on a cache line, which often
3697 // does not sit well with predictors.
3699 if (test1) goto E; // predicted not taken
3715 (A) Don't do (2) if the branch is predicted against the block we're
3716 eliminating. Do it anyway if we can eliminate a branch; this requires
3717 that the sole successor of the eliminated block postdominate the other
3720 (B) With CE, on (3) we can steal from both sides of the if, creating
3729 Again, this is most useful if J postdominates.
3731 (C) CE substitutes for helpful life information.
3733 (D) These heuristics need a lot of work. */
3735 /* Tests for case 1 above. */
3738 find_if_case_1 (basic_block test_bb, edge then_edge, edge else_edge)
3740 basic_block then_bb = then_edge->dest;
3741 basic_block else_bb = else_edge->dest;
3745 /* If we are partitioning hot/cold basic blocks, we don't want to
3746 mess up unconditional or indirect jumps that cross between hot
3749 Basic block partitioning may result in some jumps that appear to
3750 be optimizable (or blocks that appear to be mergeable), but which really
3751 must be left untouched (they are required to make it safely across
3752 partition boundaries). See the comments at the top of
3753 bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */
3755 if ((BB_END (then_bb)
3756 && find_reg_note (BB_END (then_bb), REG_CROSSING_JUMP, NULL_RTX))
3757 || (BB_END (test_bb)
3758 && find_reg_note (BB_END (test_bb), REG_CROSSING_JUMP, NULL_RTX))
3759 || (BB_END (else_bb)
3760 && find_reg_note (BB_END (else_bb), REG_CROSSING_JUMP,
3764 /* THEN has one successor. */
3765 if (!single_succ_p (then_bb))
3768 /* THEN does not fall through, but is not strange either. */
3769 if (single_succ_edge (then_bb)->flags & (EDGE_COMPLEX | EDGE_FALLTHRU))
3772 /* THEN has one predecessor. */
3773 if (!single_pred_p (then_bb))
3776 /* THEN must do something. */
3777 if (forwarder_block_p (then_bb))
3780 num_possible_if_blocks++;
3783 "\nIF-CASE-1 found, start %d, then %d\n",
3784 test_bb->index, then_bb->index);
3786 /* THEN is small. */
3787 if (! cheap_bb_rtx_cost_p (then_bb,
3788 COSTS_N_INSNS (BRANCH_COST (optimize_bb_for_speed_p (then_edge->src),
3789 predictable_edge_p (then_edge)))))
3792 /* Registers set are dead, or are predicable. */
3793 if (! dead_or_predicable (test_bb, then_bb, else_bb,
3794 single_succ (then_bb), 1))
3797 /* Conversion went ok, including moving the insns and fixing up the
3798 jump. Adjust the CFG to match. */
3800 /* We can avoid creating a new basic block if then_bb is immediately
3801 followed by else_bb, i.e. deleting then_bb allows test_bb to fall
3804 if (then_bb->next_bb == else_bb
3805 && then_bb->prev_bb == test_bb
3806 && else_bb != EXIT_BLOCK_PTR)
3808 redirect_edge_succ (FALLTHRU_EDGE (test_bb), else_bb);
3812 new_bb = redirect_edge_and_branch_force (FALLTHRU_EDGE (test_bb),
3815 df_set_bb_dirty (test_bb);
3816 df_set_bb_dirty (else_bb);
3818 then_bb_index = then_bb->index;
3819 delete_basic_block (then_bb);
3821 /* Make rest of code believe that the newly created block is the THEN_BB
3822 block we removed. */
3825 df_bb_replace (then_bb_index, new_bb);
3826 /* Since the fallthru edge was redirected from test_bb to new_bb,
3827 we need to ensure that new_bb is in the same partition as
3828 test bb (you can not fall through across section boundaries). */
3829 BB_COPY_PARTITION (new_bb, test_bb);
3833 num_updated_if_blocks++;
3838 /* Test for case 2 above. */
3841 find_if_case_2 (basic_block test_bb, edge then_edge, edge else_edge)
3843 basic_block then_bb = then_edge->dest;
3844 basic_block else_bb = else_edge->dest;
3848 /* If we are partitioning hot/cold basic blocks, we don't want to
3849 mess up unconditional or indirect jumps that cross between hot
3852 Basic block partitioning may result in some jumps that appear to
3853 be optimizable (or blocks that appear to be mergeable), but which really
3854 must be left untouched (they are required to make it safely across
3855 partition boundaries). See the comments at the top of
3856 bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */
3858 if ((BB_END (then_bb)
3859 && find_reg_note (BB_END (then_bb), REG_CROSSING_JUMP, NULL_RTX))
3860 || (BB_END (test_bb)
3861 && find_reg_note (BB_END (test_bb), REG_CROSSING_JUMP, NULL_RTX))
3862 || (BB_END (else_bb)
3863 && find_reg_note (BB_END (else_bb), REG_CROSSING_JUMP,
3867 /* ELSE has one successor. */
3868 if (!single_succ_p (else_bb))
3871 else_succ = single_succ_edge (else_bb);
3873 /* ELSE outgoing edge is not complex. */
3874 if (else_succ->flags & EDGE_COMPLEX)
3877 /* ELSE has one predecessor. */
3878 if (!single_pred_p (else_bb))
3881 /* THEN is not EXIT. */
3882 if (then_bb->index < NUM_FIXED_BLOCKS)
3885 /* ELSE is predicted or SUCC(ELSE) postdominates THEN. */
3886 note = find_reg_note (BB_END (test_bb), REG_BR_PROB, NULL_RTX);
3887 if (note && INTVAL (XEXP (note, 0)) >= REG_BR_PROB_BASE / 2)
3889 else if (else_succ->dest->index < NUM_FIXED_BLOCKS
3890 || dominated_by_p (CDI_POST_DOMINATORS, then_bb,
3896 num_possible_if_blocks++;
3899 "\nIF-CASE-2 found, start %d, else %d\n",
3900 test_bb->index, else_bb->index);
3902 /* ELSE is small. */
3903 if (! cheap_bb_rtx_cost_p (else_bb,
3904 COSTS_N_INSNS (BRANCH_COST (optimize_bb_for_speed_p (else_edge->src),
3905 predictable_edge_p (else_edge)))))
3908 /* Registers set are dead, or are predicable. */
3909 if (! dead_or_predicable (test_bb, else_bb, then_bb, else_succ->dest, 0))
3912 /* Conversion went ok, including moving the insns and fixing up the
3913 jump. Adjust the CFG to match. */
3915 df_set_bb_dirty (test_bb);
3916 df_set_bb_dirty (then_bb);
3917 delete_basic_block (else_bb);
3920 num_updated_if_blocks++;
3922 /* ??? We may now fallthru from one of THEN's successors into a join
3923 block. Rerun cleanup_cfg? Examine things manually? Wait? */
3928 /* Used by the code above to perform the actual rtl transformations.
3929 Return TRUE if successful.
3931 TEST_BB is the block containing the conditional branch. MERGE_BB
3932 is the block containing the code to manipulate. NEW_DEST is the
3933 label TEST_BB should be branching to after the conversion.
3934 REVERSEP is true if the sense of the branch should be reversed. */
3937 dead_or_predicable (basic_block test_bb, basic_block merge_bb,
3938 basic_block other_bb, basic_block new_dest, int reversep)
3940 rtx head, end, jump, earliest = NULL_RTX, old_dest, new_label = NULL_RTX;
3941 /* Number of pending changes. */
3942 int n_validated_changes = 0;
3944 jump = BB_END (test_bb);
3946 /* Find the extent of the real code in the merge block. */
3947 head = BB_HEAD (merge_bb);
3948 end = BB_END (merge_bb);
3950 while (DEBUG_INSN_P (end) && end != head)
3951 end = PREV_INSN (end);
3953 /* If merge_bb ends with a tablejump, predicating/moving insn's
3954 into test_bb and then deleting merge_bb will result in the jumptable
3955 that follows merge_bb being removed along with merge_bb and then we
3956 get an unresolved reference to the jumptable. */
3957 if (tablejump_p (end, NULL, NULL))
3961 head = NEXT_INSN (head);
3962 while (DEBUG_INSN_P (head) && head != end)
3963 head = NEXT_INSN (head);
3968 head = end = NULL_RTX;
3971 head = NEXT_INSN (head);
3972 while (DEBUG_INSN_P (head) && head != end)
3973 head = NEXT_INSN (head);
3980 head = end = NULL_RTX;
3983 end = PREV_INSN (end);
3984 while (DEBUG_INSN_P (end) && end != head)
3985 end = PREV_INSN (end);
3988 /* Disable handling dead code by conditional execution if the machine needs
3989 to do anything funny with the tests, etc. */
3990 #ifndef IFCVT_MODIFY_TESTS
3991 if (targetm.have_conditional_execution ())
3993 /* In the conditional execution case, we have things easy. We know
3994 the condition is reversible. We don't have to check life info
3995 because we're going to conditionally execute the code anyway.
3996 All that's left is making sure the insns involved can actually
4001 cond = cond_exec_get_condition (jump);
4005 prob_val = find_reg_note (jump, REG_BR_PROB, NULL_RTX);
4007 prob_val = XEXP (prob_val, 0);
4011 enum rtx_code rev = reversed_comparison_code (cond, jump);
4014 cond = gen_rtx_fmt_ee (rev, GET_MODE (cond), XEXP (cond, 0),
4017 prob_val = GEN_INT (REG_BR_PROB_BASE - INTVAL (prob_val));
4020 if (cond_exec_process_insns (NULL, head, end, cond, prob_val, 0)
4021 && verify_changes (0))
4022 n_validated_changes = num_validated_changes ();
4029 /* If we allocated new pseudos (e.g. in the conditional move
4030 expander called from noce_emit_cmove), we must resize the
4032 if (max_regno < max_reg_num ())
4033 max_regno = max_reg_num ();
4035 /* Try the NCE path if the CE path did not result in any changes. */
4036 if (n_validated_changes == 0)
4042 /* In the non-conditional execution case, we have to verify that there
4043 are no trapping operations, no calls, no references to memory, and
4044 that any registers modified are dead at the branch site. */
4046 if (!any_condjump_p (jump))
4049 /* Find the extent of the conditional. */
4050 cond = noce_get_condition (jump, &earliest, false);
4054 live = BITMAP_ALLOC (®_obstack);
4055 simulate_backwards_to_point (merge_bb, live, end);
4056 success = can_move_insns_across (head, end, earliest, jump,
4058 df_get_live_in (other_bb), NULL);
4065 /* We don't want to use normal invert_jump or redirect_jump because
4066 we don't want to delete_insn called. Also, we want to do our own
4067 change group management. */
4069 old_dest = JUMP_LABEL (jump);
4070 if (other_bb != new_dest)
4072 new_label = block_label (new_dest);
4074 ? ! invert_jump_1 (jump, new_label)
4075 : ! redirect_jump_1 (jump, new_label))
4079 if (verify_changes (n_validated_changes))
4080 confirm_change_group ();
4084 if (other_bb != new_dest)
4086 redirect_jump_2 (jump, old_dest, new_label, 0, reversep);
4088 redirect_edge_succ (BRANCH_EDGE (test_bb), new_dest);
4091 gcov_type count, probability;
4092 count = BRANCH_EDGE (test_bb)->count;
4093 BRANCH_EDGE (test_bb)->count = FALLTHRU_EDGE (test_bb)->count;
4094 FALLTHRU_EDGE (test_bb)->count = count;
4095 probability = BRANCH_EDGE (test_bb)->probability;
4096 BRANCH_EDGE (test_bb)->probability
4097 = FALLTHRU_EDGE (test_bb)->probability;
4098 FALLTHRU_EDGE (test_bb)->probability = probability;
4099 update_br_prob_note (test_bb);
4103 /* Move the insns out of MERGE_BB to before the branch. */
4108 if (end == BB_END (merge_bb))
4109 BB_END (merge_bb) = PREV_INSN (head);
4111 /* PR 21767: When moving insns above a conditional branch, REG_EQUAL
4112 notes might become invalid. */
4118 if (! INSN_P (insn))
4120 note = find_reg_note (insn, REG_EQUAL, NULL_RTX);
4123 set = single_set (insn);
4124 if (!set || !function_invariant_p (SET_SRC (set))
4125 || !function_invariant_p (XEXP (note, 0)))
4126 remove_note (insn, note);
4127 } while (insn != end && (insn = NEXT_INSN (insn)));
4129 reorder_insns (head, end, PREV_INSN (earliest));
4132 /* Remove the jump and edge if we can. */
4133 if (other_bb == new_dest)
4136 remove_edge (BRANCH_EDGE (test_bb));
4137 /* ??? Can't merge blocks here, as then_bb is still in use.
4138 At minimum, the merge will get done just before bb-reorder. */
4148 /* Main entry point for all if-conversion. */
4158 df_live_add_problem ();
4159 df_live_set_all_dirty ();
4162 num_possible_if_blocks = 0;
4163 num_updated_if_blocks = 0;
4164 num_true_changes = 0;
4166 loop_optimizer_init (AVOID_CFG_MODIFICATIONS);
4167 mark_loop_exit_edges ();
4168 loop_optimizer_finalize ();
4169 free_dominance_info (CDI_DOMINATORS);
4171 /* Compute postdominators. */
4172 calculate_dominance_info (CDI_POST_DOMINATORS);
4174 df_set_flags (DF_LR_RUN_DCE);
4176 /* Go through each of the basic blocks looking for things to convert. If we
4177 have conditional execution, we make multiple passes to allow us to handle
4178 IF-THEN{-ELSE} blocks within other IF-THEN{-ELSE} blocks. */
4183 /* Only need to do dce on the first pass. */
4184 df_clear_flags (DF_LR_RUN_DCE);
4185 cond_exec_changed_p = FALSE;
4188 #ifdef IFCVT_MULTIPLE_DUMPS
4189 if (dump_file && pass > 1)
4190 fprintf (dump_file, "\n\n========== Pass %d ==========\n", pass);
4196 while (!df_get_bb_dirty (bb)
4197 && (new_bb = find_if_header (bb, pass)) != NULL)
4201 #ifdef IFCVT_MULTIPLE_DUMPS
4202 if (dump_file && cond_exec_changed_p)
4204 if (dump_flags & TDF_SLIM)
4205 print_rtl_slim_with_bb (dump_file, get_insns (), dump_flags);
4207 print_rtl_with_bb (dump_file, get_insns ());
4211 while (cond_exec_changed_p);
4213 #ifdef IFCVT_MULTIPLE_DUMPS
4215 fprintf (dump_file, "\n\n========== no more changes\n");
4218 free_dominance_info (CDI_POST_DOMINATORS);
4223 clear_aux_for_blocks ();
4225 /* If we allocated new pseudos, we must resize the array for sched1. */
4226 if (max_regno < max_reg_num ())
4227 max_regno = max_reg_num ();
4229 /* Write the final stats. */
4230 if (dump_file && num_possible_if_blocks > 0)
4233 "\n%d possible IF blocks searched.\n",
4234 num_possible_if_blocks);
4236 "%d IF blocks converted.\n",
4237 num_updated_if_blocks);
4239 "%d true changes made.\n\n\n",
4244 df_remove_problem (df_live);
4246 #ifdef ENABLE_CHECKING
4247 verify_flow_info ();
4252 gate_handle_if_conversion (void)
4254 return (optimize > 0)
4255 && dbg_cnt (if_conversion);
4258 /* If-conversion and CFG cleanup. */
4260 rest_of_handle_if_conversion (void)
4262 if (flag_if_conversion)
4265 dump_flow_info (dump_file, dump_flags);
4266 cleanup_cfg (CLEANUP_EXPENSIVE);
4274 struct rtl_opt_pass pass_rtl_ifcvt =
4279 gate_handle_if_conversion, /* gate */
4280 rest_of_handle_if_conversion, /* execute */
4283 0, /* static_pass_number */
4284 TV_IFCVT, /* tv_id */
4285 0, /* properties_required */
4286 0, /* properties_provided */
4287 0, /* properties_destroyed */
4288 0, /* todo_flags_start */
4289 TODO_df_finish | TODO_verify_rtl_sharing |
4290 TODO_dump_func /* todo_flags_finish */
4295 gate_handle_if_after_combine (void)
4297 return optimize > 0 && flag_if_conversion
4298 && dbg_cnt (if_after_combine);
4302 /* Rerun if-conversion, as combine may have simplified things enough
4303 to now meet sequence length restrictions. */
4305 rest_of_handle_if_after_combine (void)
4311 struct rtl_opt_pass pass_if_after_combine =
4316 gate_handle_if_after_combine, /* gate */
4317 rest_of_handle_if_after_combine, /* execute */
4320 0, /* static_pass_number */
4321 TV_IFCVT, /* tv_id */
4322 0, /* properties_required */
4323 0, /* properties_provided */
4324 0, /* properties_destroyed */
4325 0, /* todo_flags_start */
4326 TODO_df_finish | TODO_verify_rtl_sharing |
4328 TODO_ggc_collect /* todo_flags_finish */
4334 gate_handle_if_after_reload (void)
4336 return optimize > 0 && flag_if_conversion2
4337 && dbg_cnt (if_after_reload);
4341 rest_of_handle_if_after_reload (void)
4348 struct rtl_opt_pass pass_if_after_reload =
4353 gate_handle_if_after_reload, /* gate */
4354 rest_of_handle_if_after_reload, /* execute */
4357 0, /* static_pass_number */
4358 TV_IFCVT2, /* tv_id */
4359 0, /* properties_required */
4360 0, /* properties_provided */
4361 0, /* properties_destroyed */
4362 0, /* todo_flags_start */
4363 TODO_df_finish | TODO_verify_rtl_sharing |
4365 TODO_ggc_collect /* todo_flags_finish */