1 /* If-conversion support.
2 Copyright (C) 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008
3 Free Software Foundation, Inc.
5 This file is part of GCC.
7 GCC is free software; you can redistribute it and/or modify it
8 under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 3, or (at your option)
12 GCC is distributed in the hope that it will be useful, but WITHOUT
13 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
14 or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public
15 License for more details.
17 You should have received a copy of the GNU General Public License
18 along with GCC; see the file COPYING3. If not see
19 <http://www.gnu.org/licenses/>. */
23 #include "coretypes.h"
30 #include "insn-config.h"
33 #include "hard-reg-set.h"
34 #include "basic-block.h"
44 #include "tree-pass.h"
50 #ifndef HAVE_conditional_execution
51 #define HAVE_conditional_execution 0
53 #ifndef HAVE_conditional_move
54 #define HAVE_conditional_move 0
66 #ifndef MAX_CONDITIONAL_EXECUTE
67 #define MAX_CONDITIONAL_EXECUTE \
68 (BRANCH_COST (optimize_function_for_speed_p (cfun), false) \
72 #define IFCVT_MULTIPLE_DUMPS 1
74 #define NULL_BLOCK ((basic_block) NULL)
76 /* # of IF-THEN or IF-THEN-ELSE blocks we looked at */
77 static int num_possible_if_blocks;
79 /* # of IF-THEN or IF-THEN-ELSE blocks were converted to conditional
81 static int num_updated_if_blocks;
83 /* # of changes made. */
84 static int num_true_changes;
86 /* Whether conditional execution changes were made. */
87 static int cond_exec_changed_p;
89 /* Forward references. */
90 static int count_bb_insns (const_basic_block);
91 static bool cheap_bb_rtx_cost_p (const_basic_block, int);
92 static rtx first_active_insn (basic_block);
93 static rtx last_active_insn (basic_block, int);
94 static basic_block block_fallthru (basic_block);
95 static int cond_exec_process_insns (ce_if_block_t *, rtx, rtx, rtx, rtx, int);
96 static rtx cond_exec_get_condition (rtx);
97 static rtx noce_get_condition (rtx, rtx *, bool);
98 static int noce_operand_ok (const_rtx);
99 static void merge_if_block (ce_if_block_t *);
100 static int find_cond_trap (basic_block, edge, edge);
101 static basic_block find_if_header (basic_block, int);
102 static int block_jumps_and_fallthru_p (basic_block, basic_block);
103 static int noce_find_if_block (basic_block, edge, edge, int);
104 static int cond_exec_find_if_block (ce_if_block_t *);
105 static int find_if_case_1 (basic_block, edge, edge);
106 static int find_if_case_2 (basic_block, edge, edge);
107 static int find_memory (rtx *, void *);
108 static int dead_or_predicable (basic_block, basic_block, basic_block,
110 static void noce_emit_move_insn (rtx, rtx);
111 static rtx block_has_only_trap (basic_block);
113 /* Count the number of non-jump active insns in BB. */
116 count_bb_insns (const_basic_block bb)
119 rtx insn = BB_HEAD (bb);
123 if (CALL_P (insn) || NONJUMP_INSN_P (insn))
126 if (insn == BB_END (bb))
128 insn = NEXT_INSN (insn);
134 /* Determine whether the total insn_rtx_cost on non-jump insns in
135 basic block BB is less than MAX_COST. This function returns
136 false if the cost of any instruction could not be estimated. */
139 cheap_bb_rtx_cost_p (const_basic_block bb, int max_cost)
142 rtx insn = BB_HEAD (bb);
143 bool speed = optimize_bb_for_speed_p (bb);
147 if (NONJUMP_INSN_P (insn))
149 int cost = insn_rtx_cost (PATTERN (insn), speed);
153 /* If this instruction is the load or set of a "stack" register,
154 such as a floating point register on x87, then the cost of
155 speculatively executing this insn may need to include
156 the additional cost of popping its result off of the
157 register stack. Unfortunately, correctly recognizing and
158 accounting for this additional overhead is tricky, so for
159 now we simply prohibit such speculative execution. */
162 rtx set = single_set (insn);
163 if (set && STACK_REG_P (SET_DEST (set)))
169 if (count >= max_cost)
172 else if (CALL_P (insn))
175 if (insn == BB_END (bb))
177 insn = NEXT_INSN (insn);
183 /* Return the first non-jump active insn in the basic block. */
186 first_active_insn (basic_block bb)
188 rtx insn = BB_HEAD (bb);
192 if (insn == BB_END (bb))
194 insn = NEXT_INSN (insn);
197 while (NOTE_P (insn) || DEBUG_INSN_P (insn))
199 if (insn == BB_END (bb))
201 insn = NEXT_INSN (insn);
210 /* Return the last non-jump active (non-jump) insn in the basic block. */
213 last_active_insn (basic_block bb, int skip_use_p)
215 rtx insn = BB_END (bb);
216 rtx head = BB_HEAD (bb);
220 || DEBUG_INSN_P (insn)
222 && NONJUMP_INSN_P (insn)
223 && GET_CODE (PATTERN (insn)) == USE))
227 insn = PREV_INSN (insn);
236 /* Return the basic block reached by falling though the basic block BB. */
239 block_fallthru (basic_block bb)
244 FOR_EACH_EDGE (e, ei, bb->succs)
245 if (e->flags & EDGE_FALLTHRU)
248 return (e) ? e->dest : NULL_BLOCK;
251 /* Go through a bunch of insns, converting them to conditional
252 execution format if possible. Return TRUE if all of the non-note
253 insns were processed. */
256 cond_exec_process_insns (ce_if_block_t *ce_info ATTRIBUTE_UNUSED,
257 /* if block information */rtx start,
258 /* first insn to look at */rtx end,
259 /* last insn to look at */rtx test,
260 /* conditional execution test */rtx prob_val,
261 /* probability of branch taken. */int mod_ok)
263 int must_be_last = FALSE;
271 for (insn = start; ; insn = NEXT_INSN (insn))
273 if (NOTE_P (insn) || DEBUG_INSN_P (insn))
276 gcc_assert(NONJUMP_INSN_P (insn) || CALL_P (insn));
278 /* Remove USE insns that get in the way. */
279 if (reload_completed && GET_CODE (PATTERN (insn)) == USE)
281 /* ??? Ug. Actually unlinking the thing is problematic,
282 given what we'd have to coordinate with our callers. */
283 SET_INSN_DELETED (insn);
287 /* Last insn wasn't last? */
291 if (modified_in_p (test, insn))
298 /* Now build the conditional form of the instruction. */
299 pattern = PATTERN (insn);
300 xtest = copy_rtx (test);
302 /* If this is already a COND_EXEC, rewrite the test to be an AND of the
304 if (GET_CODE (pattern) == COND_EXEC)
306 if (GET_MODE (xtest) != GET_MODE (COND_EXEC_TEST (pattern)))
309 xtest = gen_rtx_AND (GET_MODE (xtest), xtest,
310 COND_EXEC_TEST (pattern));
311 pattern = COND_EXEC_CODE (pattern);
314 pattern = gen_rtx_COND_EXEC (VOIDmode, xtest, pattern);
316 /* If the machine needs to modify the insn being conditionally executed,
317 say for example to force a constant integer operand into a temp
318 register, do so here. */
319 #ifdef IFCVT_MODIFY_INSN
320 IFCVT_MODIFY_INSN (ce_info, pattern, insn);
325 validate_change (insn, &PATTERN (insn), pattern, 1);
327 if (CALL_P (insn) && prob_val)
328 validate_change (insn, ®_NOTES (insn),
329 alloc_EXPR_LIST (REG_BR_PROB, prob_val,
330 REG_NOTES (insn)), 1);
340 /* Return the condition for a jump. Do not do any special processing. */
343 cond_exec_get_condition (rtx jump)
347 if (any_condjump_p (jump))
348 test_if = SET_SRC (pc_set (jump));
351 cond = XEXP (test_if, 0);
353 /* If this branches to JUMP_LABEL when the condition is false,
354 reverse the condition. */
355 if (GET_CODE (XEXP (test_if, 2)) == LABEL_REF
356 && XEXP (XEXP (test_if, 2), 0) == JUMP_LABEL (jump))
358 enum rtx_code rev = reversed_comparison_code (cond, jump);
362 cond = gen_rtx_fmt_ee (rev, GET_MODE (cond), XEXP (cond, 0),
369 /* Given a simple IF-THEN or IF-THEN-ELSE block, attempt to convert it
370 to conditional execution. Return TRUE if we were successful at
371 converting the block. */
374 cond_exec_process_if_block (ce_if_block_t * ce_info,
375 /* if block information */int do_multiple_p)
377 basic_block test_bb = ce_info->test_bb; /* last test block */
378 basic_block then_bb = ce_info->then_bb; /* THEN */
379 basic_block else_bb = ce_info->else_bb; /* ELSE or NULL */
380 rtx test_expr; /* expression in IF_THEN_ELSE that is tested */
381 rtx then_start; /* first insn in THEN block */
382 rtx then_end; /* last insn + 1 in THEN block */
383 rtx else_start = NULL_RTX; /* first insn in ELSE block or NULL */
384 rtx else_end = NULL_RTX; /* last insn + 1 in ELSE block */
385 int max; /* max # of insns to convert. */
386 int then_mod_ok; /* whether conditional mods are ok in THEN */
387 rtx true_expr; /* test for else block insns */
388 rtx false_expr; /* test for then block insns */
389 rtx true_prob_val; /* probability of else block */
390 rtx false_prob_val; /* probability of then block */
392 enum rtx_code false_code;
394 /* If test is comprised of && or || elements, and we've failed at handling
395 all of them together, just use the last test if it is the special case of
396 && elements without an ELSE block. */
397 if (!do_multiple_p && ce_info->num_multiple_test_blocks)
399 if (else_bb || ! ce_info->and_and_p)
402 ce_info->test_bb = test_bb = ce_info->last_test_bb;
403 ce_info->num_multiple_test_blocks = 0;
404 ce_info->num_and_and_blocks = 0;
405 ce_info->num_or_or_blocks = 0;
408 /* Find the conditional jump to the ELSE or JOIN part, and isolate
410 test_expr = cond_exec_get_condition (BB_END (test_bb));
414 /* If the conditional jump is more than just a conditional jump,
415 then we can not do conditional execution conversion on this block. */
416 if (! onlyjump_p (BB_END (test_bb)))
419 /* Collect the bounds of where we're to search, skipping any labels, jumps
420 and notes at the beginning and end of the block. Then count the total
421 number of insns and see if it is small enough to convert. */
422 then_start = first_active_insn (then_bb);
423 then_end = last_active_insn (then_bb, TRUE);
424 n_insns = ce_info->num_then_insns = count_bb_insns (then_bb);
425 max = MAX_CONDITIONAL_EXECUTE;
430 else_start = first_active_insn (else_bb);
431 else_end = last_active_insn (else_bb, TRUE);
432 n_insns += ce_info->num_else_insns = count_bb_insns (else_bb);
438 /* Map test_expr/test_jump into the appropriate MD tests to use on
439 the conditionally executed code. */
441 true_expr = test_expr;
443 false_code = reversed_comparison_code (true_expr, BB_END (test_bb));
444 if (false_code != UNKNOWN)
445 false_expr = gen_rtx_fmt_ee (false_code, GET_MODE (true_expr),
446 XEXP (true_expr, 0), XEXP (true_expr, 1));
448 false_expr = NULL_RTX;
450 #ifdef IFCVT_MODIFY_TESTS
451 /* If the machine description needs to modify the tests, such as setting a
452 conditional execution register from a comparison, it can do so here. */
453 IFCVT_MODIFY_TESTS (ce_info, true_expr, false_expr);
455 /* See if the conversion failed. */
456 if (!true_expr || !false_expr)
460 true_prob_val = find_reg_note (BB_END (test_bb), REG_BR_PROB, NULL_RTX);
463 true_prob_val = XEXP (true_prob_val, 0);
464 false_prob_val = GEN_INT (REG_BR_PROB_BASE - INTVAL (true_prob_val));
467 false_prob_val = NULL_RTX;
469 /* If we have && or || tests, do them here. These tests are in the adjacent
470 blocks after the first block containing the test. */
471 if (ce_info->num_multiple_test_blocks > 0)
473 basic_block bb = test_bb;
474 basic_block last_test_bb = ce_info->last_test_bb;
483 enum rtx_code f_code;
485 bb = block_fallthru (bb);
486 start = first_active_insn (bb);
487 end = last_active_insn (bb, TRUE);
489 && ! cond_exec_process_insns (ce_info, start, end, false_expr,
490 false_prob_val, FALSE))
493 /* If the conditional jump is more than just a conditional jump, then
494 we can not do conditional execution conversion on this block. */
495 if (! onlyjump_p (BB_END (bb)))
498 /* Find the conditional jump and isolate the test. */
499 t = cond_exec_get_condition (BB_END (bb));
503 f_code = reversed_comparison_code (t, BB_END (bb));
504 if (f_code == UNKNOWN)
507 f = gen_rtx_fmt_ee (f_code, GET_MODE (t), XEXP (t, 0), XEXP (t, 1));
508 if (ce_info->and_and_p)
510 t = gen_rtx_AND (GET_MODE (t), true_expr, t);
511 f = gen_rtx_IOR (GET_MODE (t), false_expr, f);
515 t = gen_rtx_IOR (GET_MODE (t), true_expr, t);
516 f = gen_rtx_AND (GET_MODE (t), false_expr, f);
519 /* If the machine description needs to modify the tests, such as
520 setting a conditional execution register from a comparison, it can
522 #ifdef IFCVT_MODIFY_MULTIPLE_TESTS
523 IFCVT_MODIFY_MULTIPLE_TESTS (ce_info, bb, t, f);
525 /* See if the conversion failed. */
533 while (bb != last_test_bb);
536 /* For IF-THEN-ELSE blocks, we don't allow modifications of the test
537 on then THEN block. */
538 then_mod_ok = (else_bb == NULL_BLOCK);
540 /* Go through the THEN and ELSE blocks converting the insns if possible
541 to conditional execution. */
545 || ! cond_exec_process_insns (ce_info, then_start, then_end,
546 false_expr, false_prob_val,
550 if (else_bb && else_end
551 && ! cond_exec_process_insns (ce_info, else_start, else_end,
552 true_expr, true_prob_val, TRUE))
555 /* If we cannot apply the changes, fail. Do not go through the normal fail
556 processing, since apply_change_group will call cancel_changes. */
557 if (! apply_change_group ())
559 #ifdef IFCVT_MODIFY_CANCEL
560 /* Cancel any machine dependent changes. */
561 IFCVT_MODIFY_CANCEL (ce_info);
566 #ifdef IFCVT_MODIFY_FINAL
567 /* Do any machine dependent final modifications. */
568 IFCVT_MODIFY_FINAL (ce_info);
571 /* Conversion succeeded. */
573 fprintf (dump_file, "%d insn%s converted to conditional execution.\n",
574 n_insns, (n_insns == 1) ? " was" : "s were");
576 /* Merge the blocks! */
577 merge_if_block (ce_info);
578 cond_exec_changed_p = TRUE;
582 #ifdef IFCVT_MODIFY_CANCEL
583 /* Cancel any machine dependent changes. */
584 IFCVT_MODIFY_CANCEL (ce_info);
591 /* Used by noce_process_if_block to communicate with its subroutines.
593 The subroutines know that A and B may be evaluated freely. They
594 know that X is a register. They should insert new instructions
595 before cond_earliest. */
599 /* The basic blocks that make up the IF-THEN-{ELSE-,}JOIN block. */
600 basic_block test_bb, then_bb, else_bb, join_bb;
602 /* The jump that ends TEST_BB. */
605 /* The jump condition. */
608 /* New insns should be inserted before this one. */
611 /* Insns in the THEN and ELSE block. There is always just this
612 one insns in those blocks. The insns are single_set insns.
613 If there was no ELSE block, INSN_B is the last insn before
614 COND_EARLIEST, or NULL_RTX. In the former case, the insn
615 operands are still valid, as if INSN_B was moved down below
619 /* The SET_SRC of INSN_A and INSN_B. */
622 /* The SET_DEST of INSN_A. */
625 /* True if this if block is not canonical. In the canonical form of
626 if blocks, the THEN_BB is the block reached via the fallthru edge
627 from TEST_BB. For the noce transformations, we allow the symmetric
629 bool then_else_reversed;
631 /* Estimated cost of the particular branch instruction. */
635 static rtx noce_emit_store_flag (struct noce_if_info *, rtx, int, int);
636 static int noce_try_move (struct noce_if_info *);
637 static int noce_try_store_flag (struct noce_if_info *);
638 static int noce_try_addcc (struct noce_if_info *);
639 static int noce_try_store_flag_constants (struct noce_if_info *);
640 static int noce_try_store_flag_mask (struct noce_if_info *);
641 static rtx noce_emit_cmove (struct noce_if_info *, rtx, enum rtx_code, rtx,
643 static int noce_try_cmove (struct noce_if_info *);
644 static int noce_try_cmove_arith (struct noce_if_info *);
645 static rtx noce_get_alt_condition (struct noce_if_info *, rtx, rtx *);
646 static int noce_try_minmax (struct noce_if_info *);
647 static int noce_try_abs (struct noce_if_info *);
648 static int noce_try_sign_mask (struct noce_if_info *);
650 /* Helper function for noce_try_store_flag*. */
653 noce_emit_store_flag (struct noce_if_info *if_info, rtx x, int reversep,
656 rtx cond = if_info->cond;
660 cond_complex = (! general_operand (XEXP (cond, 0), VOIDmode)
661 || ! general_operand (XEXP (cond, 1), VOIDmode));
663 /* If earliest == jump, or when the condition is complex, try to
664 build the store_flag insn directly. */
668 rtx set = pc_set (if_info->jump);
669 cond = XEXP (SET_SRC (set), 0);
670 if (GET_CODE (XEXP (SET_SRC (set), 2)) == LABEL_REF
671 && XEXP (XEXP (SET_SRC (set), 2), 0) == JUMP_LABEL (if_info->jump))
672 reversep = !reversep;
673 if (if_info->then_else_reversed)
674 reversep = !reversep;
678 code = reversed_comparison_code (cond, if_info->jump);
680 code = GET_CODE (cond);
682 if ((if_info->cond_earliest == if_info->jump || cond_complex)
683 && (normalize == 0 || STORE_FLAG_VALUE == normalize))
687 tmp = gen_rtx_fmt_ee (code, GET_MODE (x), XEXP (cond, 0),
689 tmp = gen_rtx_SET (VOIDmode, x, tmp);
692 tmp = emit_insn (tmp);
694 if (recog_memoized (tmp) >= 0)
700 if_info->cond_earliest = if_info->jump;
708 /* Don't even try if the comparison operands or the mode of X are weird. */
709 if (cond_complex || !SCALAR_INT_MODE_P (GET_MODE (x)))
712 return emit_store_flag (x, code, XEXP (cond, 0),
713 XEXP (cond, 1), VOIDmode,
714 (code == LTU || code == LEU
715 || code == GEU || code == GTU), normalize);
718 /* Emit instruction to move an rtx, possibly into STRICT_LOW_PART.
719 X is the destination/target and Y is the value to copy. */
722 noce_emit_move_insn (rtx x, rtx y)
724 enum machine_mode outmode;
728 if (GET_CODE (x) != STRICT_LOW_PART)
730 rtx seq, insn, target;
734 /* Check that the SET_SRC is reasonable before calling emit_move_insn,
735 otherwise construct a suitable SET pattern ourselves. */
736 insn = (OBJECT_P (y) || CONSTANT_P (y) || GET_CODE (y) == SUBREG)
737 ? emit_move_insn (x, y)
738 : emit_insn (gen_rtx_SET (VOIDmode, x, y));
742 if (recog_memoized (insn) <= 0)
744 if (GET_CODE (x) == ZERO_EXTRACT)
746 rtx op = XEXP (x, 0);
747 unsigned HOST_WIDE_INT size = INTVAL (XEXP (x, 1));
748 unsigned HOST_WIDE_INT start = INTVAL (XEXP (x, 2));
750 /* store_bit_field expects START to be relative to
751 BYTES_BIG_ENDIAN and adjusts this value for machines with
752 BITS_BIG_ENDIAN != BYTES_BIG_ENDIAN. In order to be able to
753 invoke store_bit_field again it is necessary to have the START
754 value from the first call. */
755 if (BITS_BIG_ENDIAN != BYTES_BIG_ENDIAN)
758 start = BITS_PER_UNIT - start - size;
761 gcc_assert (REG_P (op));
762 start = BITS_PER_WORD - start - size;
766 gcc_assert (start < (MEM_P (op) ? BITS_PER_UNIT : BITS_PER_WORD));
767 store_bit_field (op, size, start, GET_MODE (x), y);
771 switch (GET_RTX_CLASS (GET_CODE (y)))
774 ot = code_to_optab[GET_CODE (y)];
778 target = expand_unop (GET_MODE (y), ot, XEXP (y, 0), x, 0);
779 if (target != NULL_RTX)
782 emit_move_insn (x, target);
791 ot = code_to_optab[GET_CODE (y)];
795 target = expand_binop (GET_MODE (y), ot,
796 XEXP (y, 0), XEXP (y, 1),
798 if (target != NULL_RTX)
801 emit_move_insn (x, target);
818 inner = XEXP (outer, 0);
819 outmode = GET_MODE (outer);
820 bitpos = SUBREG_BYTE (outer) * BITS_PER_UNIT;
821 store_bit_field (inner, GET_MODE_BITSIZE (outmode), bitpos, outmode, y);
824 /* Return sequence of instructions generated by if conversion. This
825 function calls end_sequence() to end the current stream, ensures
826 that are instructions are unshared, recognizable non-jump insns.
827 On failure, this function returns a NULL_RTX. */
830 end_ifcvt_sequence (struct noce_if_info *if_info)
833 rtx seq = get_insns ();
835 set_used_flags (if_info->x);
836 set_used_flags (if_info->cond);
837 unshare_all_rtl_in_chain (seq);
840 /* Make sure that all of the instructions emitted are recognizable,
841 and that we haven't introduced a new jump instruction.
842 As an exercise for the reader, build a general mechanism that
843 allows proper placement of required clobbers. */
844 for (insn = seq; insn; insn = NEXT_INSN (insn))
846 || recog_memoized (insn) == -1)
852 /* Convert "if (a != b) x = a; else x = b" into "x = a" and
853 "if (a == b) x = a; else x = b" into "x = b". */
856 noce_try_move (struct noce_if_info *if_info)
858 rtx cond = if_info->cond;
859 enum rtx_code code = GET_CODE (cond);
862 if (code != NE && code != EQ)
865 /* This optimization isn't valid if either A or B could be a NaN
867 if (HONOR_NANS (GET_MODE (if_info->x))
868 || HONOR_SIGNED_ZEROS (GET_MODE (if_info->x)))
871 /* Check whether the operands of the comparison are A and in
873 if ((rtx_equal_p (if_info->a, XEXP (cond, 0))
874 && rtx_equal_p (if_info->b, XEXP (cond, 1)))
875 || (rtx_equal_p (if_info->a, XEXP (cond, 1))
876 && rtx_equal_p (if_info->b, XEXP (cond, 0))))
878 y = (code == EQ) ? if_info->a : if_info->b;
880 /* Avoid generating the move if the source is the destination. */
881 if (! rtx_equal_p (if_info->x, y))
884 noce_emit_move_insn (if_info->x, y);
885 seq = end_ifcvt_sequence (if_info);
889 emit_insn_before_setloc (seq, if_info->jump,
890 INSN_LOCATOR (if_info->insn_a));
897 /* Convert "if (test) x = 1; else x = 0".
899 Only try 0 and STORE_FLAG_VALUE here. Other combinations will be
900 tried in noce_try_store_flag_constants after noce_try_cmove has had
901 a go at the conversion. */
904 noce_try_store_flag (struct noce_if_info *if_info)
909 if (CONST_INT_P (if_info->b)
910 && INTVAL (if_info->b) == STORE_FLAG_VALUE
911 && if_info->a == const0_rtx)
913 else if (if_info->b == const0_rtx
914 && CONST_INT_P (if_info->a)
915 && INTVAL (if_info->a) == STORE_FLAG_VALUE
916 && (reversed_comparison_code (if_info->cond, if_info->jump)
924 target = noce_emit_store_flag (if_info, if_info->x, reversep, 0);
927 if (target != if_info->x)
928 noce_emit_move_insn (if_info->x, target);
930 seq = end_ifcvt_sequence (if_info);
934 emit_insn_before_setloc (seq, if_info->jump,
935 INSN_LOCATOR (if_info->insn_a));
945 /* Convert "if (test) x = a; else x = b", for A and B constant. */
948 noce_try_store_flag_constants (struct noce_if_info *if_info)
952 HOST_WIDE_INT itrue, ifalse, diff, tmp;
953 int normalize, can_reverse;
954 enum machine_mode mode;
956 if (CONST_INT_P (if_info->a)
957 && CONST_INT_P (if_info->b))
959 mode = GET_MODE (if_info->x);
960 ifalse = INTVAL (if_info->a);
961 itrue = INTVAL (if_info->b);
963 /* Make sure we can represent the difference between the two values. */
964 if ((itrue - ifalse > 0)
965 != ((ifalse < 0) != (itrue < 0) ? ifalse < 0 : ifalse < itrue))
968 diff = trunc_int_for_mode (itrue - ifalse, mode);
970 can_reverse = (reversed_comparison_code (if_info->cond, if_info->jump)
974 if (diff == STORE_FLAG_VALUE || diff == -STORE_FLAG_VALUE)
976 else if (ifalse == 0 && exact_log2 (itrue) >= 0
977 && (STORE_FLAG_VALUE == 1
978 || if_info->branch_cost >= 2))
980 else if (itrue == 0 && exact_log2 (ifalse) >= 0 && can_reverse
981 && (STORE_FLAG_VALUE == 1 || if_info->branch_cost >= 2))
982 normalize = 1, reversep = 1;
984 && (STORE_FLAG_VALUE == -1
985 || if_info->branch_cost >= 2))
987 else if (ifalse == -1 && can_reverse
988 && (STORE_FLAG_VALUE == -1 || if_info->branch_cost >= 2))
989 normalize = -1, reversep = 1;
990 else if ((if_info->branch_cost >= 2 && STORE_FLAG_VALUE == -1)
991 || if_info->branch_cost >= 3)
998 tmp = itrue; itrue = ifalse; ifalse = tmp;
999 diff = trunc_int_for_mode (-diff, mode);
1003 target = noce_emit_store_flag (if_info, if_info->x, reversep, normalize);
1010 /* if (test) x = 3; else x = 4;
1011 => x = 3 + (test == 0); */
1012 if (diff == STORE_FLAG_VALUE || diff == -STORE_FLAG_VALUE)
1014 target = expand_simple_binop (mode,
1015 (diff == STORE_FLAG_VALUE
1017 GEN_INT (ifalse), target, if_info->x, 0,
1021 /* if (test) x = 8; else x = 0;
1022 => x = (test != 0) << 3; */
1023 else if (ifalse == 0 && (tmp = exact_log2 (itrue)) >= 0)
1025 target = expand_simple_binop (mode, ASHIFT,
1026 target, GEN_INT (tmp), if_info->x, 0,
1030 /* if (test) x = -1; else x = b;
1031 => x = -(test != 0) | b; */
1032 else if (itrue == -1)
1034 target = expand_simple_binop (mode, IOR,
1035 target, GEN_INT (ifalse), if_info->x, 0,
1039 /* if (test) x = a; else x = b;
1040 => x = (-(test != 0) & (b - a)) + a; */
1043 target = expand_simple_binop (mode, AND,
1044 target, GEN_INT (diff), if_info->x, 0,
1047 target = expand_simple_binop (mode, PLUS,
1048 target, GEN_INT (ifalse),
1049 if_info->x, 0, OPTAB_WIDEN);
1058 if (target != if_info->x)
1059 noce_emit_move_insn (if_info->x, target);
1061 seq = end_ifcvt_sequence (if_info);
1065 emit_insn_before_setloc (seq, if_info->jump,
1066 INSN_LOCATOR (if_info->insn_a));
1073 /* Convert "if (test) foo++" into "foo += (test != 0)", and
1074 similarly for "foo--". */
1077 noce_try_addcc (struct noce_if_info *if_info)
1080 int subtract, normalize;
1082 if (GET_CODE (if_info->a) == PLUS
1083 && rtx_equal_p (XEXP (if_info->a, 0), if_info->b)
1084 && (reversed_comparison_code (if_info->cond, if_info->jump)
1087 rtx cond = if_info->cond;
1088 enum rtx_code code = reversed_comparison_code (cond, if_info->jump);
1090 /* First try to use addcc pattern. */
1091 if (general_operand (XEXP (cond, 0), VOIDmode)
1092 && general_operand (XEXP (cond, 1), VOIDmode))
1095 target = emit_conditional_add (if_info->x, code,
1100 XEXP (if_info->a, 1),
1101 GET_MODE (if_info->x),
1102 (code == LTU || code == GEU
1103 || code == LEU || code == GTU));
1106 if (target != if_info->x)
1107 noce_emit_move_insn (if_info->x, target);
1109 seq = end_ifcvt_sequence (if_info);
1113 emit_insn_before_setloc (seq, if_info->jump,
1114 INSN_LOCATOR (if_info->insn_a));
1120 /* If that fails, construct conditional increment or decrement using
1122 if (if_info->branch_cost >= 2
1123 && (XEXP (if_info->a, 1) == const1_rtx
1124 || XEXP (if_info->a, 1) == constm1_rtx))
1127 if (STORE_FLAG_VALUE == INTVAL (XEXP (if_info->a, 1)))
1128 subtract = 0, normalize = 0;
1129 else if (-STORE_FLAG_VALUE == INTVAL (XEXP (if_info->a, 1)))
1130 subtract = 1, normalize = 0;
1132 subtract = 0, normalize = INTVAL (XEXP (if_info->a, 1));
1135 target = noce_emit_store_flag (if_info,
1136 gen_reg_rtx (GET_MODE (if_info->x)),
1140 target = expand_simple_binop (GET_MODE (if_info->x),
1141 subtract ? MINUS : PLUS,
1142 if_info->b, target, if_info->x,
1146 if (target != if_info->x)
1147 noce_emit_move_insn (if_info->x, target);
1149 seq = end_ifcvt_sequence (if_info);
1153 emit_insn_before_setloc (seq, if_info->jump,
1154 INSN_LOCATOR (if_info->insn_a));
1164 /* Convert "if (test) x = 0;" to "x &= -(test == 0);" */
1167 noce_try_store_flag_mask (struct noce_if_info *if_info)
1173 if ((if_info->branch_cost >= 2
1174 || STORE_FLAG_VALUE == -1)
1175 && ((if_info->a == const0_rtx
1176 && rtx_equal_p (if_info->b, if_info->x))
1177 || ((reversep = (reversed_comparison_code (if_info->cond,
1180 && if_info->b == const0_rtx
1181 && rtx_equal_p (if_info->a, if_info->x))))
1184 target = noce_emit_store_flag (if_info,
1185 gen_reg_rtx (GET_MODE (if_info->x)),
1188 target = expand_simple_binop (GET_MODE (if_info->x), AND,
1190 target, if_info->x, 0,
1195 if (target != if_info->x)
1196 noce_emit_move_insn (if_info->x, target);
1198 seq = end_ifcvt_sequence (if_info);
1202 emit_insn_before_setloc (seq, if_info->jump,
1203 INSN_LOCATOR (if_info->insn_a));
1213 /* Helper function for noce_try_cmove and noce_try_cmove_arith. */
1216 noce_emit_cmove (struct noce_if_info *if_info, rtx x, enum rtx_code code,
1217 rtx cmp_a, rtx cmp_b, rtx vfalse, rtx vtrue)
1219 /* If earliest == jump, try to build the cmove insn directly.
1220 This is helpful when combine has created some complex condition
1221 (like for alpha's cmovlbs) that we can't hope to regenerate
1222 through the normal interface. */
1224 if (if_info->cond_earliest == if_info->jump)
1228 tmp = gen_rtx_fmt_ee (code, GET_MODE (if_info->cond), cmp_a, cmp_b);
1229 tmp = gen_rtx_IF_THEN_ELSE (GET_MODE (x), tmp, vtrue, vfalse);
1230 tmp = gen_rtx_SET (VOIDmode, x, tmp);
1233 tmp = emit_insn (tmp);
1235 if (recog_memoized (tmp) >= 0)
1247 /* Don't even try if the comparison operands are weird. */
1248 if (! general_operand (cmp_a, GET_MODE (cmp_a))
1249 || ! general_operand (cmp_b, GET_MODE (cmp_b)))
1252 #if HAVE_conditional_move
1253 return emit_conditional_move (x, code, cmp_a, cmp_b, VOIDmode,
1254 vtrue, vfalse, GET_MODE (x),
1255 (code == LTU || code == GEU
1256 || code == LEU || code == GTU));
1258 /* We'll never get here, as noce_process_if_block doesn't call the
1259 functions involved. Ifdef code, however, should be discouraged
1260 because it leads to typos in the code not selected. However,
1261 emit_conditional_move won't exist either. */
1266 /* Try only simple constants and registers here. More complex cases
1267 are handled in noce_try_cmove_arith after noce_try_store_flag_arith
1268 has had a go at it. */
1271 noce_try_cmove (struct noce_if_info *if_info)
1276 if ((CONSTANT_P (if_info->a) || register_operand (if_info->a, VOIDmode))
1277 && (CONSTANT_P (if_info->b) || register_operand (if_info->b, VOIDmode)))
1281 code = GET_CODE (if_info->cond);
1282 target = noce_emit_cmove (if_info, if_info->x, code,
1283 XEXP (if_info->cond, 0),
1284 XEXP (if_info->cond, 1),
1285 if_info->a, if_info->b);
1289 if (target != if_info->x)
1290 noce_emit_move_insn (if_info->x, target);
1292 seq = end_ifcvt_sequence (if_info);
1296 emit_insn_before_setloc (seq, if_info->jump,
1297 INSN_LOCATOR (if_info->insn_a));
1310 /* Try more complex cases involving conditional_move. */
1313 noce_try_cmove_arith (struct noce_if_info *if_info)
1325 /* A conditional move from two memory sources is equivalent to a
1326 conditional on their addresses followed by a load. Don't do this
1327 early because it'll screw alias analysis. Note that we've
1328 already checked for no side effects. */
1329 /* ??? FIXME: Magic number 5. */
1330 if (cse_not_expected
1331 && MEM_P (a) && MEM_P (b)
1332 && if_info->branch_cost >= 5)
1336 x = gen_reg_rtx (Pmode);
1340 /* ??? We could handle this if we knew that a load from A or B could
1341 not fault. This is also true if we've already loaded
1342 from the address along the path from ENTRY. */
1343 else if (may_trap_p (a) || may_trap_p (b))
1346 /* if (test) x = a + b; else x = c - d;
1353 code = GET_CODE (if_info->cond);
1354 insn_a = if_info->insn_a;
1355 insn_b = if_info->insn_b;
1357 /* Total insn_rtx_cost should be smaller than branch cost. Exit
1358 if insn_rtx_cost can't be estimated. */
1361 insn_cost = insn_rtx_cost (PATTERN (insn_a),
1362 optimize_bb_for_speed_p (BLOCK_FOR_INSN (insn_a)));
1363 if (insn_cost == 0 || insn_cost > COSTS_N_INSNS (if_info->branch_cost))
1371 insn_cost += insn_rtx_cost (PATTERN (insn_b),
1372 optimize_bb_for_speed_p (BLOCK_FOR_INSN (insn_b)));
1373 if (insn_cost == 0 || insn_cost > COSTS_N_INSNS (if_info->branch_cost))
1377 /* Possibly rearrange operands to make things come out more natural. */
1378 if (reversed_comparison_code (if_info->cond, if_info->jump) != UNKNOWN)
1381 if (rtx_equal_p (b, x))
1383 else if (general_operand (b, GET_MODE (b)))
1388 code = reversed_comparison_code (if_info->cond, if_info->jump);
1389 tmp = a, a = b, b = tmp;
1390 tmp = insn_a, insn_a = insn_b, insn_b = tmp;
1399 /* If either operand is complex, load it into a register first.
1400 The best way to do this is to copy the original insn. In this
1401 way we preserve any clobbers etc that the insn may have had.
1402 This is of course not possible in the IS_MEM case. */
1403 if (! general_operand (a, GET_MODE (a)))
1409 tmp = gen_reg_rtx (GET_MODE (a));
1410 tmp = emit_insn (gen_rtx_SET (VOIDmode, tmp, a));
1413 goto end_seq_and_fail;
1416 a = gen_reg_rtx (GET_MODE (a));
1417 tmp = copy_rtx (insn_a);
1418 set = single_set (tmp);
1420 tmp = emit_insn (PATTERN (tmp));
1422 if (recog_memoized (tmp) < 0)
1423 goto end_seq_and_fail;
1425 if (! general_operand (b, GET_MODE (b)))
1431 tmp = gen_reg_rtx (GET_MODE (b));
1432 tmp = gen_rtx_SET (VOIDmode, tmp, b);
1435 goto end_seq_and_fail;
1438 b = gen_reg_rtx (GET_MODE (b));
1439 tmp = copy_rtx (insn_b);
1440 set = single_set (tmp);
1442 tmp = PATTERN (tmp);
1445 /* If insn to set up A clobbers any registers B depends on, try to
1446 swap insn that sets up A with the one that sets up B. If even
1447 that doesn't help, punt. */
1448 last = get_last_insn ();
1449 if (last && modified_in_p (orig_b, last))
1451 tmp = emit_insn_before (tmp, get_insns ());
1452 if (modified_in_p (orig_a, tmp))
1453 goto end_seq_and_fail;
1456 tmp = emit_insn (tmp);
1458 if (recog_memoized (tmp) < 0)
1459 goto end_seq_and_fail;
1462 target = noce_emit_cmove (if_info, x, code, XEXP (if_info->cond, 0),
1463 XEXP (if_info->cond, 1), a, b);
1466 goto end_seq_and_fail;
1468 /* If we're handling a memory for above, emit the load now. */
1471 tmp = gen_rtx_MEM (GET_MODE (if_info->x), target);
1473 /* Copy over flags as appropriate. */
1474 if (MEM_VOLATILE_P (if_info->a) || MEM_VOLATILE_P (if_info->b))
1475 MEM_VOLATILE_P (tmp) = 1;
1476 if (MEM_IN_STRUCT_P (if_info->a) && MEM_IN_STRUCT_P (if_info->b))
1477 MEM_IN_STRUCT_P (tmp) = 1;
1478 if (MEM_SCALAR_P (if_info->a) && MEM_SCALAR_P (if_info->b))
1479 MEM_SCALAR_P (tmp) = 1;
1480 if (MEM_ALIAS_SET (if_info->a) == MEM_ALIAS_SET (if_info->b))
1481 set_mem_alias_set (tmp, MEM_ALIAS_SET (if_info->a));
1483 MIN (MEM_ALIGN (if_info->a), MEM_ALIGN (if_info->b)));
1485 noce_emit_move_insn (if_info->x, tmp);
1487 else if (target != x)
1488 noce_emit_move_insn (x, target);
1490 tmp = end_ifcvt_sequence (if_info);
1494 emit_insn_before_setloc (tmp, if_info->jump, INSN_LOCATOR (if_info->insn_a));
1502 /* For most cases, the simplified condition we found is the best
1503 choice, but this is not the case for the min/max/abs transforms.
1504 For these we wish to know that it is A or B in the condition. */
1507 noce_get_alt_condition (struct noce_if_info *if_info, rtx target,
1510 rtx cond, set, insn;
1513 /* If target is already mentioned in the known condition, return it. */
1514 if (reg_mentioned_p (target, if_info->cond))
1516 *earliest = if_info->cond_earliest;
1517 return if_info->cond;
1520 set = pc_set (if_info->jump);
1521 cond = XEXP (SET_SRC (set), 0);
1523 = GET_CODE (XEXP (SET_SRC (set), 2)) == LABEL_REF
1524 && XEXP (XEXP (SET_SRC (set), 2), 0) == JUMP_LABEL (if_info->jump);
1525 if (if_info->then_else_reversed)
1528 /* If we're looking for a constant, try to make the conditional
1529 have that constant in it. There are two reasons why it may
1530 not have the constant we want:
1532 1. GCC may have needed to put the constant in a register, because
1533 the target can't compare directly against that constant. For
1534 this case, we look for a SET immediately before the comparison
1535 that puts a constant in that register.
1537 2. GCC may have canonicalized the conditional, for example
1538 replacing "if x < 4" with "if x <= 3". We can undo that (or
1539 make equivalent types of changes) to get the constants we need
1540 if they're off by one in the right direction. */
1542 if (CONST_INT_P (target))
1544 enum rtx_code code = GET_CODE (if_info->cond);
1545 rtx op_a = XEXP (if_info->cond, 0);
1546 rtx op_b = XEXP (if_info->cond, 1);
1549 /* First, look to see if we put a constant in a register. */
1550 prev_insn = prev_nonnote_insn (if_info->cond_earliest);
1552 && BLOCK_NUM (prev_insn) == BLOCK_NUM (if_info->cond_earliest)
1553 && INSN_P (prev_insn)
1554 && GET_CODE (PATTERN (prev_insn)) == SET)
1556 rtx src = find_reg_equal_equiv_note (prev_insn);
1558 src = SET_SRC (PATTERN (prev_insn));
1559 if (CONST_INT_P (src))
1561 if (rtx_equal_p (op_a, SET_DEST (PATTERN (prev_insn))))
1563 else if (rtx_equal_p (op_b, SET_DEST (PATTERN (prev_insn))))
1566 if (CONST_INT_P (op_a))
1571 code = swap_condition (code);
1576 /* Now, look to see if we can get the right constant by
1577 adjusting the conditional. */
1578 if (CONST_INT_P (op_b))
1580 HOST_WIDE_INT desired_val = INTVAL (target);
1581 HOST_WIDE_INT actual_val = INTVAL (op_b);
1586 if (actual_val == desired_val + 1)
1589 op_b = GEN_INT (desired_val);
1593 if (actual_val == desired_val - 1)
1596 op_b = GEN_INT (desired_val);
1600 if (actual_val == desired_val - 1)
1603 op_b = GEN_INT (desired_val);
1607 if (actual_val == desired_val + 1)
1610 op_b = GEN_INT (desired_val);
1618 /* If we made any changes, generate a new conditional that is
1619 equivalent to what we started with, but has the right
1621 if (code != GET_CODE (if_info->cond)
1622 || op_a != XEXP (if_info->cond, 0)
1623 || op_b != XEXP (if_info->cond, 1))
1625 cond = gen_rtx_fmt_ee (code, GET_MODE (cond), op_a, op_b);
1626 *earliest = if_info->cond_earliest;
1631 cond = canonicalize_condition (if_info->jump, cond, reverse,
1632 earliest, target, false, true);
1633 if (! cond || ! reg_mentioned_p (target, cond))
1636 /* We almost certainly searched back to a different place.
1637 Need to re-verify correct lifetimes. */
1639 /* X may not be mentioned in the range (cond_earliest, jump]. */
1640 for (insn = if_info->jump; insn != *earliest; insn = PREV_INSN (insn))
1641 if (INSN_P (insn) && reg_overlap_mentioned_p (if_info->x, PATTERN (insn)))
1644 /* A and B may not be modified in the range [cond_earliest, jump). */
1645 for (insn = *earliest; insn != if_info->jump; insn = NEXT_INSN (insn))
1647 && (modified_in_p (if_info->a, insn)
1648 || modified_in_p (if_info->b, insn)))
1654 /* Convert "if (a < b) x = a; else x = b;" to "x = min(a, b);", etc. */
1657 noce_try_minmax (struct noce_if_info *if_info)
1659 rtx cond, earliest, target, seq;
1660 enum rtx_code code, op;
1663 /* ??? Reject modes with NaNs or signed zeros since we don't know how
1664 they will be resolved with an SMIN/SMAX. It wouldn't be too hard
1665 to get the target to tell us... */
1666 if (HONOR_SIGNED_ZEROS (GET_MODE (if_info->x))
1667 || HONOR_NANS (GET_MODE (if_info->x)))
1670 cond = noce_get_alt_condition (if_info, if_info->a, &earliest);
1674 /* Verify the condition is of the form we expect, and canonicalize
1675 the comparison code. */
1676 code = GET_CODE (cond);
1677 if (rtx_equal_p (XEXP (cond, 0), if_info->a))
1679 if (! rtx_equal_p (XEXP (cond, 1), if_info->b))
1682 else if (rtx_equal_p (XEXP (cond, 1), if_info->a))
1684 if (! rtx_equal_p (XEXP (cond, 0), if_info->b))
1686 code = swap_condition (code);
1691 /* Determine what sort of operation this is. Note that the code is for
1692 a taken branch, so the code->operation mapping appears backwards. */
1725 target = expand_simple_binop (GET_MODE (if_info->x), op,
1726 if_info->a, if_info->b,
1727 if_info->x, unsignedp, OPTAB_WIDEN);
1733 if (target != if_info->x)
1734 noce_emit_move_insn (if_info->x, target);
1736 seq = end_ifcvt_sequence (if_info);
1740 emit_insn_before_setloc (seq, if_info->jump, INSN_LOCATOR (if_info->insn_a));
1741 if_info->cond = cond;
1742 if_info->cond_earliest = earliest;
1747 /* Convert "if (a < 0) x = -a; else x = a;" to "x = abs(a);", etc. */
1750 noce_try_abs (struct noce_if_info *if_info)
1752 rtx cond, earliest, target, seq, a, b, c;
1755 /* Reject modes with signed zeros. */
1756 if (HONOR_SIGNED_ZEROS (GET_MODE (if_info->x)))
1759 /* Recognize A and B as constituting an ABS or NABS. The canonical
1760 form is a branch around the negation, taken when the object is the
1761 first operand of a comparison against 0 that evaluates to true. */
1764 if (GET_CODE (a) == NEG && rtx_equal_p (XEXP (a, 0), b))
1766 else if (GET_CODE (b) == NEG && rtx_equal_p (XEXP (b, 0), a))
1768 c = a; a = b; b = c;
1774 cond = noce_get_alt_condition (if_info, b, &earliest);
1778 /* Verify the condition is of the form we expect. */
1779 if (rtx_equal_p (XEXP (cond, 0), b))
1781 else if (rtx_equal_p (XEXP (cond, 1), b))
1789 /* Verify that C is zero. Search one step backward for a
1790 REG_EQUAL note or a simple source if necessary. */
1793 rtx set, insn = prev_nonnote_insn (earliest);
1795 && BLOCK_NUM (insn) == BLOCK_NUM (earliest)
1796 && (set = single_set (insn))
1797 && rtx_equal_p (SET_DEST (set), c))
1799 rtx note = find_reg_equal_equiv_note (insn);
1809 && GET_CODE (XEXP (c, 0)) == SYMBOL_REF
1810 && CONSTANT_POOL_ADDRESS_P (XEXP (c, 0)))
1811 c = get_pool_constant (XEXP (c, 0));
1813 /* Work around funny ideas get_condition has wrt canonicalization.
1814 Note that these rtx constants are known to be CONST_INT, and
1815 therefore imply integer comparisons. */
1816 if (c == constm1_rtx && GET_CODE (cond) == GT)
1818 else if (c == const1_rtx && GET_CODE (cond) == LT)
1820 else if (c != CONST0_RTX (GET_MODE (b)))
1823 /* Determine what sort of operation this is. */
1824 switch (GET_CODE (cond))
1843 target = expand_abs_nojump (GET_MODE (if_info->x), b, if_info->x, 1);
1845 /* ??? It's a quandary whether cmove would be better here, especially
1846 for integers. Perhaps combine will clean things up. */
1847 if (target && negate)
1848 target = expand_simple_unop (GET_MODE (target), NEG, target, if_info->x, 0);
1856 if (target != if_info->x)
1857 noce_emit_move_insn (if_info->x, target);
1859 seq = end_ifcvt_sequence (if_info);
1863 emit_insn_before_setloc (seq, if_info->jump, INSN_LOCATOR (if_info->insn_a));
1864 if_info->cond = cond;
1865 if_info->cond_earliest = earliest;
1870 /* Convert "if (m < 0) x = b; else x = 0;" to "x = (m >> C) & b;". */
1873 noce_try_sign_mask (struct noce_if_info *if_info)
1875 rtx cond, t, m, c, seq;
1876 enum machine_mode mode;
1878 bool t_unconditional;
1880 cond = if_info->cond;
1881 code = GET_CODE (cond);
1886 if (if_info->a == const0_rtx)
1888 if ((code == LT && c == const0_rtx)
1889 || (code == LE && c == constm1_rtx))
1892 else if (if_info->b == const0_rtx)
1894 if ((code == GE && c == const0_rtx)
1895 || (code == GT && c == constm1_rtx))
1899 if (! t || side_effects_p (t))
1902 /* We currently don't handle different modes. */
1903 mode = GET_MODE (t);
1904 if (GET_MODE (m) != mode)
1907 /* This is only profitable if T is unconditionally executed/evaluated in the
1908 original insn sequence or T is cheap. The former happens if B is the
1909 non-zero (T) value and if INSN_B was taken from TEST_BB, or there was no
1910 INSN_B which can happen for e.g. conditional stores to memory. For the
1911 cost computation use the block TEST_BB where the evaluation will end up
1912 after the transformation. */
1915 && (if_info->insn_b == NULL_RTX
1916 || BLOCK_FOR_INSN (if_info->insn_b) == if_info->test_bb));
1917 if (!(t_unconditional
1918 || (rtx_cost (t, SET, optimize_bb_for_speed_p (if_info->test_bb))
1919 < COSTS_N_INSNS (2))))
1923 /* Use emit_store_flag to generate "m < 0 ? -1 : 0" instead of expanding
1924 "(signed) m >> 31" directly. This benefits targets with specialized
1925 insns to obtain the signmask, but still uses ashr_optab otherwise. */
1926 m = emit_store_flag (gen_reg_rtx (mode), LT, m, const0_rtx, mode, 0, -1);
1927 t = m ? expand_binop (mode, and_optab, m, t, NULL_RTX, 0, OPTAB_DIRECT)
1936 noce_emit_move_insn (if_info->x, t);
1938 seq = end_ifcvt_sequence (if_info);
1942 emit_insn_before_setloc (seq, if_info->jump, INSN_LOCATOR (if_info->insn_a));
1947 /* Optimize away "if (x & C) x |= C" and similar bit manipulation
1951 noce_try_bitop (struct noce_if_info *if_info)
1953 rtx cond, x, a, result, seq;
1954 enum machine_mode mode;
1959 cond = if_info->cond;
1960 code = GET_CODE (cond);
1962 /* Check for no else condition. */
1963 if (! rtx_equal_p (x, if_info->b))
1966 /* Check for a suitable condition. */
1967 if (code != NE && code != EQ)
1969 if (XEXP (cond, 1) != const0_rtx)
1971 cond = XEXP (cond, 0);
1973 /* ??? We could also handle AND here. */
1974 if (GET_CODE (cond) == ZERO_EXTRACT)
1976 if (XEXP (cond, 1) != const1_rtx
1977 || !CONST_INT_P (XEXP (cond, 2))
1978 || ! rtx_equal_p (x, XEXP (cond, 0)))
1980 bitnum = INTVAL (XEXP (cond, 2));
1981 mode = GET_MODE (x);
1982 if (BITS_BIG_ENDIAN)
1983 bitnum = GET_MODE_BITSIZE (mode) - 1 - bitnum;
1984 if (bitnum < 0 || bitnum >= HOST_BITS_PER_WIDE_INT)
1991 if (GET_CODE (a) == IOR || GET_CODE (a) == XOR)
1993 /* Check for "if (X & C) x = x op C". */
1994 if (! rtx_equal_p (x, XEXP (a, 0))
1995 || !CONST_INT_P (XEXP (a, 1))
1996 || (INTVAL (XEXP (a, 1)) & GET_MODE_MASK (mode))
1997 != (unsigned HOST_WIDE_INT) 1 << bitnum)
2000 /* if ((x & C) == 0) x |= C; is transformed to x |= C. */
2001 /* if ((x & C) != 0) x |= C; is transformed to nothing. */
2002 if (GET_CODE (a) == IOR)
2003 result = (code == NE) ? a : NULL_RTX;
2004 else if (code == NE)
2006 /* if ((x & C) == 0) x ^= C; is transformed to x |= C. */
2007 result = gen_int_mode ((HOST_WIDE_INT) 1 << bitnum, mode);
2008 result = simplify_gen_binary (IOR, mode, x, result);
2012 /* if ((x & C) != 0) x ^= C; is transformed to x &= ~C. */
2013 result = gen_int_mode (~((HOST_WIDE_INT) 1 << bitnum), mode);
2014 result = simplify_gen_binary (AND, mode, x, result);
2017 else if (GET_CODE (a) == AND)
2019 /* Check for "if (X & C) x &= ~C". */
2020 if (! rtx_equal_p (x, XEXP (a, 0))
2021 || !CONST_INT_P (XEXP (a, 1))
2022 || (INTVAL (XEXP (a, 1)) & GET_MODE_MASK (mode))
2023 != (~((HOST_WIDE_INT) 1 << bitnum) & GET_MODE_MASK (mode)))
2026 /* if ((x & C) == 0) x &= ~C; is transformed to nothing. */
2027 /* if ((x & C) != 0) x &= ~C; is transformed to x &= ~C. */
2028 result = (code == EQ) ? a : NULL_RTX;
2036 noce_emit_move_insn (x, result);
2037 seq = end_ifcvt_sequence (if_info);
2041 emit_insn_before_setloc (seq, if_info->jump,
2042 INSN_LOCATOR (if_info->insn_a));
2048 /* Similar to get_condition, only the resulting condition must be
2049 valid at JUMP, instead of at EARLIEST.
2051 If THEN_ELSE_REVERSED is true, the fallthrough does not go to the
2052 THEN block of the caller, and we have to reverse the condition. */
2055 noce_get_condition (rtx jump, rtx *earliest, bool then_else_reversed)
2060 if (! any_condjump_p (jump))
2063 set = pc_set (jump);
2065 /* If this branches to JUMP_LABEL when the condition is false,
2066 reverse the condition. */
2067 reverse = (GET_CODE (XEXP (SET_SRC (set), 2)) == LABEL_REF
2068 && XEXP (XEXP (SET_SRC (set), 2), 0) == JUMP_LABEL (jump));
2070 /* We may have to reverse because the caller's if block is not canonical,
2071 i.e. the THEN block isn't the fallthrough block for the TEST block
2072 (see find_if_header). */
2073 if (then_else_reversed)
2076 /* If the condition variable is a register and is MODE_INT, accept it. */
2078 cond = XEXP (SET_SRC (set), 0);
2079 tmp = XEXP (cond, 0);
2080 if (REG_P (tmp) && GET_MODE_CLASS (GET_MODE (tmp)) == MODE_INT)
2085 cond = gen_rtx_fmt_ee (reverse_condition (GET_CODE (cond)),
2086 GET_MODE (cond), tmp, XEXP (cond, 1));
2090 /* Otherwise, fall back on canonicalize_condition to do the dirty
2091 work of manipulating MODE_CC values and COMPARE rtx codes. */
2092 return canonicalize_condition (jump, cond, reverse, earliest,
2093 NULL_RTX, false, true);
2096 /* Return true if OP is ok for if-then-else processing. */
2099 noce_operand_ok (const_rtx op)
2101 /* We special-case memories, so handle any of them with
2102 no address side effects. */
2104 return ! side_effects_p (XEXP (op, 0));
2106 if (side_effects_p (op))
2109 return ! may_trap_p (op);
2112 /* Return true if a write into MEM may trap or fault. */
2115 noce_mem_write_may_trap_or_fault_p (const_rtx mem)
2119 if (MEM_READONLY_P (mem))
2122 if (may_trap_or_fault_p (mem))
2125 addr = XEXP (mem, 0);
2127 /* Call target hook to avoid the effects of -fpic etc.... */
2128 addr = targetm.delegitimize_address (addr);
2131 switch (GET_CODE (addr))
2139 addr = XEXP (addr, 0);
2143 addr = XEXP (addr, 1);
2146 if (CONST_INT_P (XEXP (addr, 1)))
2147 addr = XEXP (addr, 0);
2154 if (SYMBOL_REF_DECL (addr)
2155 && decl_readonly_section (SYMBOL_REF_DECL (addr), 0))
2165 /* Return whether we can use store speculation for MEM. TOP_BB is the
2166 basic block above the conditional block where we are considering
2167 doing the speculative store. We look for whether MEM is set
2168 unconditionally later in the function. */
2171 noce_can_store_speculate_p (basic_block top_bb, const_rtx mem)
2173 basic_block dominator;
2175 for (dominator = get_immediate_dominator (CDI_POST_DOMINATORS, top_bb);
2177 dominator = get_immediate_dominator (CDI_POST_DOMINATORS, dominator))
2181 FOR_BB_INSNS (dominator, insn)
2183 /* If we see something that might be a memory barrier, we
2184 have to stop looking. Even if the MEM is set later in
2185 the function, we still don't want to set it
2186 unconditionally before the barrier. */
2188 && (volatile_insn_p (PATTERN (insn))
2189 || (CALL_P (insn) && (!RTL_CONST_CALL_P (insn)))))
2192 if (memory_modified_in_insn_p (mem, insn))
2194 if (modified_in_p (XEXP (mem, 0), insn))
2203 /* Given a simple IF-THEN-JOIN or IF-THEN-ELSE-JOIN block, attempt to convert
2204 it without using conditional execution. Return TRUE if we were successful
2205 at converting the block. */
2208 noce_process_if_block (struct noce_if_info *if_info)
2210 basic_block test_bb = if_info->test_bb; /* test block */
2211 basic_block then_bb = if_info->then_bb; /* THEN */
2212 basic_block else_bb = if_info->else_bb; /* ELSE or NULL */
2213 basic_block join_bb = if_info->join_bb; /* JOIN */
2214 rtx jump = if_info->jump;
2215 rtx cond = if_info->cond;
2218 rtx orig_x, x, a, b;
2220 /* We're looking for patterns of the form
2222 (1) if (...) x = a; else x = b;
2223 (2) x = b; if (...) x = a;
2224 (3) if (...) x = a; // as if with an initial x = x.
2226 The later patterns require jumps to be more expensive.
2228 ??? For future expansion, look for multiple X in such patterns. */
2230 /* Look for one of the potential sets. */
2231 insn_a = first_active_insn (then_bb);
2233 || insn_a != last_active_insn (then_bb, FALSE)
2234 || (set_a = single_set (insn_a)) == NULL_RTX)
2237 x = SET_DEST (set_a);
2238 a = SET_SRC (set_a);
2240 /* Look for the other potential set. Make sure we've got equivalent
2242 /* ??? This is overconservative. Storing to two different mems is
2243 as easy as conditionally computing the address. Storing to a
2244 single mem merely requires a scratch memory to use as one of the
2245 destination addresses; often the memory immediately below the
2246 stack pointer is available for this. */
2250 insn_b = first_active_insn (else_bb);
2252 || insn_b != last_active_insn (else_bb, FALSE)
2253 || (set_b = single_set (insn_b)) == NULL_RTX
2254 || ! rtx_equal_p (x, SET_DEST (set_b)))
2259 insn_b = prev_nonnote_insn (if_info->cond_earliest);
2260 while (insn_b && DEBUG_INSN_P (insn_b))
2261 insn_b = prev_nonnote_insn (insn_b);
2262 /* We're going to be moving the evaluation of B down from above
2263 COND_EARLIEST to JUMP. Make sure the relevant data is still
2266 || BLOCK_NUM (insn_b) != BLOCK_NUM (if_info->cond_earliest)
2267 || !NONJUMP_INSN_P (insn_b)
2268 || (set_b = single_set (insn_b)) == NULL_RTX
2269 || ! rtx_equal_p (x, SET_DEST (set_b))
2270 || ! noce_operand_ok (SET_SRC (set_b))
2271 || reg_overlap_mentioned_p (x, SET_SRC (set_b))
2272 || modified_between_p (SET_SRC (set_b), insn_b, jump)
2273 /* Likewise with X. In particular this can happen when
2274 noce_get_condition looks farther back in the instruction
2275 stream than one might expect. */
2276 || reg_overlap_mentioned_p (x, cond)
2277 || reg_overlap_mentioned_p (x, a)
2278 || modified_between_p (x, insn_b, jump))
2279 insn_b = set_b = NULL_RTX;
2282 /* If x has side effects then only the if-then-else form is safe to
2283 convert. But even in that case we would need to restore any notes
2284 (such as REG_INC) at then end. That can be tricky if
2285 noce_emit_move_insn expands to more than one insn, so disable the
2286 optimization entirely for now if there are side effects. */
2287 if (side_effects_p (x))
2290 b = (set_b ? SET_SRC (set_b) : x);
2292 /* Only operate on register destinations, and even then avoid extending
2293 the lifetime of hard registers on small register class machines. */
2296 || (SMALL_REGISTER_CLASSES
2297 && REGNO (x) < FIRST_PSEUDO_REGISTER))
2299 if (GET_MODE (x) == BLKmode)
2302 if (GET_CODE (x) == ZERO_EXTRACT
2303 && (!CONST_INT_P (XEXP (x, 1))
2304 || !CONST_INT_P (XEXP (x, 2))))
2307 x = gen_reg_rtx (GET_MODE (GET_CODE (x) == STRICT_LOW_PART
2308 ? XEXP (x, 0) : x));
2311 /* Don't operate on sources that may trap or are volatile. */
2312 if (! noce_operand_ok (a) || ! noce_operand_ok (b))
2316 /* Set up the info block for our subroutines. */
2317 if_info->insn_a = insn_a;
2318 if_info->insn_b = insn_b;
2323 /* Try optimizations in some approximation of a useful order. */
2324 /* ??? Should first look to see if X is live incoming at all. If it
2325 isn't, we don't need anything but an unconditional set. */
2327 /* Look and see if A and B are really the same. Avoid creating silly
2328 cmove constructs that no one will fix up later. */
2329 if (rtx_equal_p (a, b))
2331 /* If we have an INSN_B, we don't have to create any new rtl. Just
2332 move the instruction that we already have. If we don't have an
2333 INSN_B, that means that A == X, and we've got a noop move. In
2334 that case don't do anything and let the code below delete INSN_A. */
2335 if (insn_b && else_bb)
2339 if (else_bb && insn_b == BB_END (else_bb))
2340 BB_END (else_bb) = PREV_INSN (insn_b);
2341 reorder_insns (insn_b, insn_b, PREV_INSN (jump));
2343 /* If there was a REG_EQUAL note, delete it since it may have been
2344 true due to this insn being after a jump. */
2345 if ((note = find_reg_note (insn_b, REG_EQUAL, NULL_RTX)) != 0)
2346 remove_note (insn_b, note);
2350 /* If we have "x = b; if (...) x = a;", and x has side-effects, then
2351 x must be executed twice. */
2352 else if (insn_b && side_effects_p (orig_x))
2359 if (!set_b && MEM_P (orig_x))
2361 /* Disallow the "if (...) x = a;" form (implicit "else x = x;")
2362 for optimizations if writing to x may trap or fault,
2363 i.e. it's a memory other than a static var or a stack slot,
2364 is misaligned on strict aligned machines or is read-only. If
2365 x is a read-only memory, then the program is valid only if we
2366 avoid the store into it. If there are stores on both the
2367 THEN and ELSE arms, then we can go ahead with the conversion;
2368 either the program is broken, or the condition is always
2369 false such that the other memory is selected. */
2370 if (noce_mem_write_may_trap_or_fault_p (orig_x))
2373 /* Avoid store speculation: given "if (...) x = a" where x is a
2374 MEM, we only want to do the store if x is always set
2375 somewhere in the function. This avoids cases like
2376 if (pthread_mutex_trylock(mutex))
2378 where we only want global_variable to be changed if the mutex
2379 is held. FIXME: This should ideally be expressed directly in
2381 if (!noce_can_store_speculate_p (test_bb, orig_x))
2385 if (noce_try_move (if_info))
2387 if (noce_try_store_flag (if_info))
2389 if (noce_try_bitop (if_info))
2391 if (noce_try_minmax (if_info))
2393 if (noce_try_abs (if_info))
2395 if (HAVE_conditional_move
2396 && noce_try_cmove (if_info))
2398 if (! HAVE_conditional_execution)
2400 if (noce_try_store_flag_constants (if_info))
2402 if (noce_try_addcc (if_info))
2404 if (noce_try_store_flag_mask (if_info))
2406 if (HAVE_conditional_move
2407 && noce_try_cmove_arith (if_info))
2409 if (noce_try_sign_mask (if_info))
2413 if (!else_bb && set_b)
2415 insn_b = set_b = NULL_RTX;
2424 /* If we used a temporary, fix it up now. */
2430 noce_emit_move_insn (orig_x, x);
2432 set_used_flags (orig_x);
2433 unshare_all_rtl_in_chain (seq);
2436 emit_insn_before_setloc (seq, BB_END (test_bb), INSN_LOCATOR (insn_a));
2439 /* The original THEN and ELSE blocks may now be removed. The test block
2440 must now jump to the join block. If the test block and the join block
2441 can be merged, do so. */
2444 delete_basic_block (else_bb);
2448 remove_edge (find_edge (test_bb, join_bb));
2450 remove_edge (find_edge (then_bb, join_bb));
2451 redirect_edge_and_branch_force (single_succ_edge (test_bb), join_bb);
2452 delete_basic_block (then_bb);
2455 if (can_merge_blocks_p (test_bb, join_bb))
2457 merge_blocks (test_bb, join_bb);
2461 num_updated_if_blocks++;
2465 /* Check whether a block is suitable for conditional move conversion.
2466 Every insn must be a simple set of a register to a constant or a
2467 register. For each assignment, store the value in the array VALS,
2468 indexed by register number, then store the register number in
2469 REGS. COND is the condition we will test. */
2472 check_cond_move_block (basic_block bb, rtx *vals, VEC (int, heap) **regs, rtx cond)
2476 /* We can only handle simple jumps at the end of the basic block.
2477 It is almost impossible to update the CFG otherwise. */
2479 if (JUMP_P (insn) && !onlyjump_p (insn))
2482 FOR_BB_INSNS (bb, insn)
2486 if (!NONDEBUG_INSN_P (insn) || JUMP_P (insn))
2488 set = single_set (insn);
2492 dest = SET_DEST (set);
2493 src = SET_SRC (set);
2495 || (SMALL_REGISTER_CLASSES && HARD_REGISTER_P (dest)))
2498 if (!CONSTANT_P (src) && !register_operand (src, VOIDmode))
2501 if (side_effects_p (src) || side_effects_p (dest))
2504 if (may_trap_p (src) || may_trap_p (dest))
2507 /* Don't try to handle this if the source register was
2508 modified earlier in the block. */
2510 && vals[REGNO (src)] != NULL)
2511 || (GET_CODE (src) == SUBREG && REG_P (SUBREG_REG (src))
2512 && vals[REGNO (SUBREG_REG (src))] != NULL))
2515 /* Don't try to handle this if the destination register was
2516 modified earlier in the block. */
2517 if (vals[REGNO (dest)] != NULL)
2520 /* Don't try to handle this if the condition uses the
2521 destination register. */
2522 if (reg_overlap_mentioned_p (dest, cond))
2525 /* Don't try to handle this if the source register is modified
2526 later in the block. */
2527 if (!CONSTANT_P (src)
2528 && modified_between_p (src, insn, NEXT_INSN (BB_END (bb))))
2531 vals[REGNO (dest)] = src;
2533 VEC_safe_push (int, heap, *regs, REGNO (dest));
2539 /* Given a basic block BB suitable for conditional move conversion,
2540 a condition COND, and arrays THEN_VALS and ELSE_VALS containing the
2541 register values depending on COND, emit the insns in the block as
2542 conditional moves. If ELSE_BLOCK is true, THEN_BB was already
2543 processed. The caller has started a sequence for the conversion.
2544 Return true if successful, false if something goes wrong. */
2547 cond_move_convert_if_block (struct noce_if_info *if_infop,
2548 basic_block bb, rtx cond,
2549 rtx *then_vals, rtx *else_vals,
2553 rtx insn, cond_arg0, cond_arg1;
2555 code = GET_CODE (cond);
2556 cond_arg0 = XEXP (cond, 0);
2557 cond_arg1 = XEXP (cond, 1);
2559 FOR_BB_INSNS (bb, insn)
2561 rtx set, target, dest, t, e;
2564 /* ??? Maybe emit conditional debug insn? */
2565 if (!NONDEBUG_INSN_P (insn) || JUMP_P (insn))
2567 set = single_set (insn);
2568 gcc_assert (set && REG_P (SET_DEST (set)));
2570 dest = SET_DEST (set);
2571 regno = REGNO (dest);
2573 t = then_vals[regno];
2574 e = else_vals[regno];
2578 /* If this register was set in the then block, we already
2579 handled this case there. */
2592 target = noce_emit_cmove (if_infop, dest, code, cond_arg0, cond_arg1,
2598 noce_emit_move_insn (dest, target);
2604 /* Given a simple IF-THEN-JOIN or IF-THEN-ELSE-JOIN block, attempt to convert
2605 it using only conditional moves. Return TRUE if we were successful at
2606 converting the block. */
2609 cond_move_process_if_block (struct noce_if_info *if_info)
2611 basic_block test_bb = if_info->test_bb;
2612 basic_block then_bb = if_info->then_bb;
2613 basic_block else_bb = if_info->else_bb;
2614 basic_block join_bb = if_info->join_bb;
2615 rtx jump = if_info->jump;
2616 rtx cond = if_info->cond;
2618 int max_reg, size, c, reg;
2621 VEC (int, heap) *then_regs = NULL;
2622 VEC (int, heap) *else_regs = NULL;
2625 /* Build a mapping for each block to the value used for each
2627 max_reg = max_reg_num ();
2628 size = (max_reg + 1) * sizeof (rtx);
2629 then_vals = (rtx *) alloca (size);
2630 else_vals = (rtx *) alloca (size);
2631 memset (then_vals, 0, size);
2632 memset (else_vals, 0, size);
2634 /* Make sure the blocks are suitable. */
2635 if (!check_cond_move_block (then_bb, then_vals, &then_regs, cond)
2636 || (else_bb && !check_cond_move_block (else_bb, else_vals, &else_regs, cond)))
2638 VEC_free (int, heap, then_regs);
2639 VEC_free (int, heap, else_regs);
2643 /* Make sure the blocks can be used together. If the same register
2644 is set in both blocks, and is not set to a constant in both
2645 cases, then both blocks must set it to the same register. We
2646 have already verified that if it is set to a register, that the
2647 source register does not change after the assignment. Also count
2648 the number of registers set in only one of the blocks. */
2650 for (i = 0; VEC_iterate (int, then_regs, i, reg); i++)
2652 if (!then_vals[reg] && !else_vals[reg])
2655 if (!else_vals[reg])
2659 if (!CONSTANT_P (then_vals[reg])
2660 && !CONSTANT_P (else_vals[reg])
2661 && !rtx_equal_p (then_vals[reg], else_vals[reg]))
2663 VEC_free (int, heap, then_regs);
2664 VEC_free (int, heap, else_regs);
2670 /* Finish off c for MAX_CONDITIONAL_EXECUTE. */
2671 for (i = 0; VEC_iterate (int, else_regs, i, reg); ++i)
2672 if (!then_vals[reg])
2675 /* Make sure it is reasonable to convert this block. What matters
2676 is the number of assignments currently made in only one of the
2677 branches, since if we convert we are going to always execute
2679 if (c > MAX_CONDITIONAL_EXECUTE)
2681 VEC_free (int, heap, then_regs);
2682 VEC_free (int, heap, else_regs);
2686 /* Try to emit the conditional moves. First do the then block,
2687 then do anything left in the else blocks. */
2689 if (!cond_move_convert_if_block (if_info, then_bb, cond,
2690 then_vals, else_vals, false)
2692 && !cond_move_convert_if_block (if_info, else_bb, cond,
2693 then_vals, else_vals, true)))
2696 VEC_free (int, heap, then_regs);
2697 VEC_free (int, heap, else_regs);
2700 seq = end_ifcvt_sequence (if_info);
2703 VEC_free (int, heap, then_regs);
2704 VEC_free (int, heap, else_regs);
2708 loc_insn = first_active_insn (then_bb);
2711 loc_insn = first_active_insn (else_bb);
2712 gcc_assert (loc_insn);
2714 emit_insn_before_setloc (seq, jump, INSN_LOCATOR (loc_insn));
2718 delete_basic_block (else_bb);
2722 remove_edge (find_edge (test_bb, join_bb));
2724 remove_edge (find_edge (then_bb, join_bb));
2725 redirect_edge_and_branch_force (single_succ_edge (test_bb), join_bb);
2726 delete_basic_block (then_bb);
2729 if (can_merge_blocks_p (test_bb, join_bb))
2731 merge_blocks (test_bb, join_bb);
2735 num_updated_if_blocks++;
2737 VEC_free (int, heap, then_regs);
2738 VEC_free (int, heap, else_regs);
2743 /* Determine if a given basic block heads a simple IF-THEN-JOIN or an
2744 IF-THEN-ELSE-JOIN block.
2746 If so, we'll try to convert the insns to not require the branch,
2747 using only transformations that do not require conditional execution.
2749 Return TRUE if we were successful at converting the block. */
2752 noce_find_if_block (basic_block test_bb,
2753 edge then_edge, edge else_edge,
2756 basic_block then_bb, else_bb, join_bb;
2757 bool then_else_reversed = false;
2760 struct noce_if_info if_info;
2762 /* We only ever should get here before reload. */
2763 gcc_assert (!reload_completed);
2765 /* Recognize an IF-THEN-ELSE-JOIN block. */
2766 if (single_pred_p (then_edge->dest)
2767 && single_succ_p (then_edge->dest)
2768 && single_pred_p (else_edge->dest)
2769 && single_succ_p (else_edge->dest)
2770 && single_succ (then_edge->dest) == single_succ (else_edge->dest))
2772 then_bb = then_edge->dest;
2773 else_bb = else_edge->dest;
2774 join_bb = single_succ (then_bb);
2776 /* Recognize an IF-THEN-JOIN block. */
2777 else if (single_pred_p (then_edge->dest)
2778 && single_succ_p (then_edge->dest)
2779 && single_succ (then_edge->dest) == else_edge->dest)
2781 then_bb = then_edge->dest;
2782 else_bb = NULL_BLOCK;
2783 join_bb = else_edge->dest;
2785 /* Recognize an IF-ELSE-JOIN block. We can have those because the order
2786 of basic blocks in cfglayout mode does not matter, so the fallthrough
2787 edge can go to any basic block (and not just to bb->next_bb, like in
2789 else if (single_pred_p (else_edge->dest)
2790 && single_succ_p (else_edge->dest)
2791 && single_succ (else_edge->dest) == then_edge->dest)
2793 /* The noce transformations do not apply to IF-ELSE-JOIN blocks.
2794 To make this work, we have to invert the THEN and ELSE blocks
2795 and reverse the jump condition. */
2796 then_bb = else_edge->dest;
2797 else_bb = NULL_BLOCK;
2798 join_bb = single_succ (then_bb);
2799 then_else_reversed = true;
2802 /* Not a form we can handle. */
2805 /* The edges of the THEN and ELSE blocks cannot have complex edges. */
2806 if (single_succ_edge (then_bb)->flags & EDGE_COMPLEX)
2809 && single_succ_edge (else_bb)->flags & EDGE_COMPLEX)
2812 num_possible_if_blocks++;
2817 "\nIF-THEN%s-JOIN block found, pass %d, test %d, then %d",
2818 (else_bb) ? "-ELSE" : "",
2819 pass, test_bb->index, then_bb->index);
2822 fprintf (dump_file, ", else %d", else_bb->index);
2824 fprintf (dump_file, ", join %d\n", join_bb->index);
2827 /* If the conditional jump is more than just a conditional
2828 jump, then we can not do if-conversion on this block. */
2829 jump = BB_END (test_bb);
2830 if (! onlyjump_p (jump))
2833 /* If this is not a standard conditional jump, we can't parse it. */
2834 cond = noce_get_condition (jump,
2836 then_else_reversed);
2840 /* We must be comparing objects whose modes imply the size. */
2841 if (GET_MODE (XEXP (cond, 0)) == BLKmode)
2844 /* Initialize an IF_INFO struct to pass around. */
2845 memset (&if_info, 0, sizeof if_info);
2846 if_info.test_bb = test_bb;
2847 if_info.then_bb = then_bb;
2848 if_info.else_bb = else_bb;
2849 if_info.join_bb = join_bb;
2850 if_info.cond = cond;
2851 if_info.cond_earliest = cond_earliest;
2852 if_info.jump = jump;
2853 if_info.then_else_reversed = then_else_reversed;
2854 if_info.branch_cost = BRANCH_COST (optimize_bb_for_speed_p (test_bb),
2855 predictable_edge_p (then_edge));
2857 /* Do the real work. */
2859 if (noce_process_if_block (&if_info))
2862 if (HAVE_conditional_move
2863 && cond_move_process_if_block (&if_info))
2870 /* Merge the blocks and mark for local life update. */
2873 merge_if_block (struct ce_if_block * ce_info)
2875 basic_block test_bb = ce_info->test_bb; /* last test block */
2876 basic_block then_bb = ce_info->then_bb; /* THEN */
2877 basic_block else_bb = ce_info->else_bb; /* ELSE or NULL */
2878 basic_block join_bb = ce_info->join_bb; /* join block */
2879 basic_block combo_bb;
2881 /* All block merging is done into the lower block numbers. */
2884 df_set_bb_dirty (test_bb);
2886 /* Merge any basic blocks to handle && and || subtests. Each of
2887 the blocks are on the fallthru path from the predecessor block. */
2888 if (ce_info->num_multiple_test_blocks > 0)
2890 basic_block bb = test_bb;
2891 basic_block last_test_bb = ce_info->last_test_bb;
2892 basic_block fallthru = block_fallthru (bb);
2897 fallthru = block_fallthru (bb);
2898 merge_blocks (combo_bb, bb);
2901 while (bb != last_test_bb);
2904 /* Merge TEST block into THEN block. Normally the THEN block won't have a
2905 label, but it might if there were || tests. That label's count should be
2906 zero, and it normally should be removed. */
2910 merge_blocks (combo_bb, then_bb);
2914 /* The ELSE block, if it existed, had a label. That label count
2915 will almost always be zero, but odd things can happen when labels
2916 get their addresses taken. */
2919 merge_blocks (combo_bb, else_bb);
2923 /* If there was no join block reported, that means it was not adjacent
2924 to the others, and so we cannot merge them. */
2928 rtx last = BB_END (combo_bb);
2930 /* The outgoing edge for the current COMBO block should already
2931 be correct. Verify this. */
2932 if (EDGE_COUNT (combo_bb->succs) == 0)
2933 gcc_assert (find_reg_note (last, REG_NORETURN, NULL)
2934 || (NONJUMP_INSN_P (last)
2935 && GET_CODE (PATTERN (last)) == TRAP_IF
2936 && (TRAP_CONDITION (PATTERN (last))
2937 == const_true_rtx)));
2940 /* There should still be something at the end of the THEN or ELSE
2941 blocks taking us to our final destination. */
2942 gcc_assert (JUMP_P (last)
2943 || (EDGE_SUCC (combo_bb, 0)->dest == EXIT_BLOCK_PTR
2945 && SIBLING_CALL_P (last))
2946 || ((EDGE_SUCC (combo_bb, 0)->flags & EDGE_EH)
2947 && can_throw_internal (last)));
2950 /* The JOIN block may have had quite a number of other predecessors too.
2951 Since we've already merged the TEST, THEN and ELSE blocks, we should
2952 have only one remaining edge from our if-then-else diamond. If there
2953 is more than one remaining edge, it must come from elsewhere. There
2954 may be zero incoming edges if the THEN block didn't actually join
2955 back up (as with a call to a non-return function). */
2956 else if (EDGE_COUNT (join_bb->preds) < 2
2957 && join_bb != EXIT_BLOCK_PTR)
2959 /* We can merge the JOIN cleanly and update the dataflow try
2960 again on this pass.*/
2961 merge_blocks (combo_bb, join_bb);
2966 /* We cannot merge the JOIN. */
2968 /* The outgoing edge for the current COMBO block should already
2969 be correct. Verify this. */
2970 gcc_assert (single_succ_p (combo_bb)
2971 && single_succ (combo_bb) == join_bb);
2973 /* Remove the jump and cruft from the end of the COMBO block. */
2974 if (join_bb != EXIT_BLOCK_PTR)
2975 tidy_fallthru_edge (single_succ_edge (combo_bb));
2978 num_updated_if_blocks++;
2981 /* Find a block ending in a simple IF condition and try to transform it
2982 in some way. When converting a multi-block condition, put the new code
2983 in the first such block and delete the rest. Return a pointer to this
2984 first block if some transformation was done. Return NULL otherwise. */
2987 find_if_header (basic_block test_bb, int pass)
2989 ce_if_block_t ce_info;
2993 /* The kind of block we're looking for has exactly two successors. */
2994 if (EDGE_COUNT (test_bb->succs) != 2)
2997 then_edge = EDGE_SUCC (test_bb, 0);
2998 else_edge = EDGE_SUCC (test_bb, 1);
3000 if (df_get_bb_dirty (then_edge->dest))
3002 if (df_get_bb_dirty (else_edge->dest))
3005 /* Neither edge should be abnormal. */
3006 if ((then_edge->flags & EDGE_COMPLEX)
3007 || (else_edge->flags & EDGE_COMPLEX))
3010 /* Nor exit the loop. */
3011 if ((then_edge->flags & EDGE_LOOP_EXIT)
3012 || (else_edge->flags & EDGE_LOOP_EXIT))
3015 /* The THEN edge is canonically the one that falls through. */
3016 if (then_edge->flags & EDGE_FALLTHRU)
3018 else if (else_edge->flags & EDGE_FALLTHRU)
3021 else_edge = then_edge;
3025 /* Otherwise this must be a multiway branch of some sort. */
3028 memset (&ce_info, '\0', sizeof (ce_info));
3029 ce_info.test_bb = test_bb;
3030 ce_info.then_bb = then_edge->dest;
3031 ce_info.else_bb = else_edge->dest;
3032 ce_info.pass = pass;
3034 #ifdef IFCVT_INIT_EXTRA_FIELDS
3035 IFCVT_INIT_EXTRA_FIELDS (&ce_info);
3038 if (! reload_completed
3039 && noce_find_if_block (test_bb, then_edge, else_edge, pass))
3042 if (HAVE_conditional_execution && reload_completed
3043 && cond_exec_find_if_block (&ce_info))
3047 && optab_handler (ctrap_optab, word_mode)->insn_code != CODE_FOR_nothing
3048 && find_cond_trap (test_bb, then_edge, else_edge))
3051 if (dom_info_state (CDI_POST_DOMINATORS) >= DOM_NO_FAST_QUERY
3052 && (! HAVE_conditional_execution || reload_completed))
3054 if (find_if_case_1 (test_bb, then_edge, else_edge))
3056 if (find_if_case_2 (test_bb, then_edge, else_edge))
3064 fprintf (dump_file, "Conversion succeeded on pass %d.\n", pass);
3065 /* Set this so we continue looking. */
3066 cond_exec_changed_p = TRUE;
3067 return ce_info.test_bb;
3070 /* Return true if a block has two edges, one of which falls through to the next
3071 block, and the other jumps to a specific block, so that we can tell if the
3072 block is part of an && test or an || test. Returns either -1 or the number
3073 of non-note, non-jump, non-USE/CLOBBER insns in the block. */
3076 block_jumps_and_fallthru_p (basic_block cur_bb, basic_block target_bb)
3079 int fallthru_p = FALSE;
3086 if (!cur_bb || !target_bb)
3089 /* If no edges, obviously it doesn't jump or fallthru. */
3090 if (EDGE_COUNT (cur_bb->succs) == 0)
3093 FOR_EACH_EDGE (cur_edge, ei, cur_bb->succs)
3095 if (cur_edge->flags & EDGE_COMPLEX)
3096 /* Anything complex isn't what we want. */
3099 else if (cur_edge->flags & EDGE_FALLTHRU)
3102 else if (cur_edge->dest == target_bb)
3109 if ((jump_p & fallthru_p) == 0)
3112 /* Don't allow calls in the block, since this is used to group && and ||
3113 together for conditional execution support. ??? we should support
3114 conditional execution support across calls for IA-64 some day, but
3115 for now it makes the code simpler. */
3116 end = BB_END (cur_bb);
3117 insn = BB_HEAD (cur_bb);
3119 while (insn != NULL_RTX)
3126 && !DEBUG_INSN_P (insn)
3127 && GET_CODE (PATTERN (insn)) != USE
3128 && GET_CODE (PATTERN (insn)) != CLOBBER)
3134 insn = NEXT_INSN (insn);
3140 /* Determine if a given basic block heads a simple IF-THEN or IF-THEN-ELSE
3141 block. If so, we'll try to convert the insns to not require the branch.
3142 Return TRUE if we were successful at converting the block. */
3145 cond_exec_find_if_block (struct ce_if_block * ce_info)
3147 basic_block test_bb = ce_info->test_bb;
3148 basic_block then_bb = ce_info->then_bb;
3149 basic_block else_bb = ce_info->else_bb;
3150 basic_block join_bb = NULL_BLOCK;
3155 ce_info->last_test_bb = test_bb;
3157 /* We only ever should get here after reload,
3158 and only if we have conditional execution. */
3159 gcc_assert (HAVE_conditional_execution && reload_completed);
3161 /* Discover if any fall through predecessors of the current test basic block
3162 were && tests (which jump to the else block) or || tests (which jump to
3164 if (single_pred_p (test_bb)
3165 && single_pred_edge (test_bb)->flags == EDGE_FALLTHRU)
3167 basic_block bb = single_pred (test_bb);
3168 basic_block target_bb;
3169 int max_insns = MAX_CONDITIONAL_EXECUTE;
3172 /* Determine if the preceding block is an && or || block. */
3173 if ((n_insns = block_jumps_and_fallthru_p (bb, else_bb)) >= 0)
3175 ce_info->and_and_p = TRUE;
3176 target_bb = else_bb;
3178 else if ((n_insns = block_jumps_and_fallthru_p (bb, then_bb)) >= 0)
3180 ce_info->and_and_p = FALSE;
3181 target_bb = then_bb;
3184 target_bb = NULL_BLOCK;
3186 if (target_bb && n_insns <= max_insns)
3188 int total_insns = 0;
3191 ce_info->last_test_bb = test_bb;
3193 /* Found at least one && or || block, look for more. */
3196 ce_info->test_bb = test_bb = bb;
3197 total_insns += n_insns;
3200 if (!single_pred_p (bb))
3203 bb = single_pred (bb);
3204 n_insns = block_jumps_and_fallthru_p (bb, target_bb);
3206 while (n_insns >= 0 && (total_insns + n_insns) <= max_insns);
3208 ce_info->num_multiple_test_blocks = blocks;
3209 ce_info->num_multiple_test_insns = total_insns;
3211 if (ce_info->and_and_p)
3212 ce_info->num_and_and_blocks = blocks;
3214 ce_info->num_or_or_blocks = blocks;
3218 /* The THEN block of an IF-THEN combo must have exactly one predecessor,
3219 other than any || blocks which jump to the THEN block. */
3220 if ((EDGE_COUNT (then_bb->preds) - ce_info->num_or_or_blocks) != 1)
3223 /* The edges of the THEN and ELSE blocks cannot have complex edges. */
3224 FOR_EACH_EDGE (cur_edge, ei, then_bb->preds)
3226 if (cur_edge->flags & EDGE_COMPLEX)
3230 FOR_EACH_EDGE (cur_edge, ei, else_bb->preds)
3232 if (cur_edge->flags & EDGE_COMPLEX)
3236 /* The THEN block of an IF-THEN combo must have zero or one successors. */
3237 if (EDGE_COUNT (then_bb->succs) > 0
3238 && (!single_succ_p (then_bb)
3239 || (single_succ_edge (then_bb)->flags & EDGE_COMPLEX)
3240 || (epilogue_completed && tablejump_p (BB_END (then_bb), NULL, NULL))))
3243 /* If the THEN block has no successors, conditional execution can still
3244 make a conditional call. Don't do this unless the ELSE block has
3245 only one incoming edge -- the CFG manipulation is too ugly otherwise.
3246 Check for the last insn of the THEN block being an indirect jump, which
3247 is listed as not having any successors, but confuses the rest of the CE
3248 code processing. ??? we should fix this in the future. */
3249 if (EDGE_COUNT (then_bb->succs) == 0)
3251 if (single_pred_p (else_bb))
3253 rtx last_insn = BB_END (then_bb);
3256 && NOTE_P (last_insn)
3257 && last_insn != BB_HEAD (then_bb))
3258 last_insn = PREV_INSN (last_insn);
3261 && JUMP_P (last_insn)
3262 && ! simplejump_p (last_insn))
3266 else_bb = NULL_BLOCK;
3272 /* If the THEN block's successor is the other edge out of the TEST block,
3273 then we have an IF-THEN combo without an ELSE. */
3274 else if (single_succ (then_bb) == else_bb)
3277 else_bb = NULL_BLOCK;
3280 /* If the THEN and ELSE block meet in a subsequent block, and the ELSE
3281 has exactly one predecessor and one successor, and the outgoing edge
3282 is not complex, then we have an IF-THEN-ELSE combo. */
3283 else if (single_succ_p (else_bb)
3284 && single_succ (then_bb) == single_succ (else_bb)
3285 && single_pred_p (else_bb)
3286 && ! (single_succ_edge (else_bb)->flags & EDGE_COMPLEX)
3287 && ! (epilogue_completed && tablejump_p (BB_END (else_bb), NULL, NULL)))
3288 join_bb = single_succ (else_bb);
3290 /* Otherwise it is not an IF-THEN or IF-THEN-ELSE combination. */
3294 num_possible_if_blocks++;
3299 "\nIF-THEN%s block found, pass %d, start block %d "
3300 "[insn %d], then %d [%d]",
3301 (else_bb) ? "-ELSE" : "",
3304 BB_HEAD (test_bb) ? (int)INSN_UID (BB_HEAD (test_bb)) : -1,
3306 BB_HEAD (then_bb) ? (int)INSN_UID (BB_HEAD (then_bb)) : -1);
3309 fprintf (dump_file, ", else %d [%d]",
3311 BB_HEAD (else_bb) ? (int)INSN_UID (BB_HEAD (else_bb)) : -1);
3313 fprintf (dump_file, ", join %d [%d]",
3315 BB_HEAD (join_bb) ? (int)INSN_UID (BB_HEAD (join_bb)) : -1);
3317 if (ce_info->num_multiple_test_blocks > 0)
3318 fprintf (dump_file, ", %d %s block%s last test %d [%d]",
3319 ce_info->num_multiple_test_blocks,
3320 (ce_info->and_and_p) ? "&&" : "||",
3321 (ce_info->num_multiple_test_blocks == 1) ? "" : "s",
3322 ce_info->last_test_bb->index,
3323 ((BB_HEAD (ce_info->last_test_bb))
3324 ? (int)INSN_UID (BB_HEAD (ce_info->last_test_bb))
3327 fputc ('\n', dump_file);
3330 /* Make sure IF, THEN, and ELSE, blocks are adjacent. Actually, we get the
3331 first condition for free, since we've already asserted that there's a
3332 fallthru edge from IF to THEN. Likewise for the && and || blocks, since
3333 we checked the FALLTHRU flag, those are already adjacent to the last IF
3335 /* ??? As an enhancement, move the ELSE block. Have to deal with
3336 BLOCK notes, if by no other means than backing out the merge if they
3337 exist. Sticky enough I don't want to think about it now. */
3339 if (else_bb && (next = next->next_bb) != else_bb)
3341 if ((next = next->next_bb) != join_bb && join_bb != EXIT_BLOCK_PTR)
3349 /* Do the real work. */
3351 ce_info->else_bb = else_bb;
3352 ce_info->join_bb = join_bb;
3354 /* If we have && and || tests, try to first handle combining the && and ||
3355 tests into the conditional code, and if that fails, go back and handle
3356 it without the && and ||, which at present handles the && case if there
3357 was no ELSE block. */
3358 if (cond_exec_process_if_block (ce_info, TRUE))
3361 if (ce_info->num_multiple_test_blocks)
3365 if (cond_exec_process_if_block (ce_info, FALSE))
3372 /* Convert a branch over a trap, or a branch
3373 to a trap, into a conditional trap. */
3376 find_cond_trap (basic_block test_bb, edge then_edge, edge else_edge)
3378 basic_block then_bb = then_edge->dest;
3379 basic_block else_bb = else_edge->dest;
3380 basic_block other_bb, trap_bb;
3381 rtx trap, jump, cond, cond_earliest, seq;
3384 /* Locate the block with the trap instruction. */
3385 /* ??? While we look for no successors, we really ought to allow
3386 EH successors. Need to fix merge_if_block for that to work. */
3387 if ((trap = block_has_only_trap (then_bb)) != NULL)
3388 trap_bb = then_bb, other_bb = else_bb;
3389 else if ((trap = block_has_only_trap (else_bb)) != NULL)
3390 trap_bb = else_bb, other_bb = then_bb;
3396 fprintf (dump_file, "\nTRAP-IF block found, start %d, trap %d\n",
3397 test_bb->index, trap_bb->index);
3400 /* If this is not a standard conditional jump, we can't parse it. */
3401 jump = BB_END (test_bb);
3402 cond = noce_get_condition (jump, &cond_earliest, false);
3406 /* If the conditional jump is more than just a conditional jump, then
3407 we can not do if-conversion on this block. */
3408 if (! onlyjump_p (jump))
3411 /* We must be comparing objects whose modes imply the size. */
3412 if (GET_MODE (XEXP (cond, 0)) == BLKmode)
3415 /* Reverse the comparison code, if necessary. */
3416 code = GET_CODE (cond);
3417 if (then_bb == trap_bb)
3419 code = reversed_comparison_code (cond, jump);
3420 if (code == UNKNOWN)
3424 /* Attempt to generate the conditional trap. */
3425 seq = gen_cond_trap (code, copy_rtx (XEXP (cond, 0)),
3426 copy_rtx (XEXP (cond, 1)),
3427 TRAP_CODE (PATTERN (trap)));
3431 /* Emit the new insns before cond_earliest. */
3432 emit_insn_before_setloc (seq, cond_earliest, INSN_LOCATOR (trap));
3434 /* Delete the trap block if possible. */
3435 remove_edge (trap_bb == then_bb ? then_edge : else_edge);
3436 df_set_bb_dirty (test_bb);
3437 df_set_bb_dirty (then_bb);
3438 df_set_bb_dirty (else_bb);
3440 if (EDGE_COUNT (trap_bb->preds) == 0)
3442 delete_basic_block (trap_bb);
3446 /* Wire together the blocks again. */
3447 if (current_ir_type () == IR_RTL_CFGLAYOUT)
3448 single_succ_edge (test_bb)->flags |= EDGE_FALLTHRU;
3453 lab = JUMP_LABEL (jump);
3454 newjump = emit_jump_insn_after (gen_jump (lab), jump);
3455 LABEL_NUSES (lab) += 1;
3456 JUMP_LABEL (newjump) = lab;
3457 emit_barrier_after (newjump);
3461 if (can_merge_blocks_p (test_bb, other_bb))
3463 merge_blocks (test_bb, other_bb);
3467 num_updated_if_blocks++;
3471 /* Subroutine of find_cond_trap: if BB contains only a trap insn,
3475 block_has_only_trap (basic_block bb)
3479 /* We're not the exit block. */
3480 if (bb == EXIT_BLOCK_PTR)
3483 /* The block must have no successors. */
3484 if (EDGE_COUNT (bb->succs) > 0)
3487 /* The only instruction in the THEN block must be the trap. */
3488 trap = first_active_insn (bb);
3489 if (! (trap == BB_END (bb)
3490 && GET_CODE (PATTERN (trap)) == TRAP_IF
3491 && TRAP_CONDITION (PATTERN (trap)) == const_true_rtx))
3497 /* Look for IF-THEN-ELSE cases in which one of THEN or ELSE is
3498 transformable, but not necessarily the other. There need be no
3501 Return TRUE if we were successful at converting the block.
3503 Cases we'd like to look at:
3506 if (test) goto over; // x not live
3514 if (! test) goto label;
3517 if (test) goto E; // x not live
3531 (3) // This one's really only interesting for targets that can do
3532 // multiway branching, e.g. IA-64 BBB bundles. For other targets
3533 // it results in multiple branches on a cache line, which often
3534 // does not sit well with predictors.
3536 if (test1) goto E; // predicted not taken
3552 (A) Don't do (2) if the branch is predicted against the block we're
3553 eliminating. Do it anyway if we can eliminate a branch; this requires
3554 that the sole successor of the eliminated block postdominate the other
3557 (B) With CE, on (3) we can steal from both sides of the if, creating
3566 Again, this is most useful if J postdominates.
3568 (C) CE substitutes for helpful life information.
3570 (D) These heuristics need a lot of work. */
3572 /* Tests for case 1 above. */
3575 find_if_case_1 (basic_block test_bb, edge then_edge, edge else_edge)
3577 basic_block then_bb = then_edge->dest;
3578 basic_block else_bb = else_edge->dest;
3582 /* If we are partitioning hot/cold basic blocks, we don't want to
3583 mess up unconditional or indirect jumps that cross between hot
3586 Basic block partitioning may result in some jumps that appear to
3587 be optimizable (or blocks that appear to be mergeable), but which really
3588 must be left untouched (they are required to make it safely across
3589 partition boundaries). See the comments at the top of
3590 bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */
3592 if ((BB_END (then_bb)
3593 && find_reg_note (BB_END (then_bb), REG_CROSSING_JUMP, NULL_RTX))
3594 || (BB_END (test_bb)
3595 && find_reg_note (BB_END (test_bb), REG_CROSSING_JUMP, NULL_RTX))
3596 || (BB_END (else_bb)
3597 && find_reg_note (BB_END (else_bb), REG_CROSSING_JUMP,
3601 /* THEN has one successor. */
3602 if (!single_succ_p (then_bb))
3605 /* THEN does not fall through, but is not strange either. */
3606 if (single_succ_edge (then_bb)->flags & (EDGE_COMPLEX | EDGE_FALLTHRU))
3609 /* THEN has one predecessor. */
3610 if (!single_pred_p (then_bb))
3613 /* THEN must do something. */
3614 if (forwarder_block_p (then_bb))
3617 num_possible_if_blocks++;
3620 "\nIF-CASE-1 found, start %d, then %d\n",
3621 test_bb->index, then_bb->index);
3623 /* THEN is small. */
3624 if (! cheap_bb_rtx_cost_p (then_bb,
3625 COSTS_N_INSNS (BRANCH_COST (optimize_bb_for_speed_p (then_edge->src),
3626 predictable_edge_p (then_edge)))))
3629 /* Registers set are dead, or are predicable. */
3630 if (! dead_or_predicable (test_bb, then_bb, else_bb,
3631 single_succ (then_bb), 1))
3634 /* Conversion went ok, including moving the insns and fixing up the
3635 jump. Adjust the CFG to match. */
3637 /* We can avoid creating a new basic block if then_bb is immediately
3638 followed by else_bb, i.e. deleting then_bb allows test_bb to fall
3641 if (then_bb->next_bb == else_bb
3642 && then_bb->prev_bb == test_bb
3643 && else_bb != EXIT_BLOCK_PTR)
3645 redirect_edge_succ (FALLTHRU_EDGE (test_bb), else_bb);
3649 new_bb = redirect_edge_and_branch_force (FALLTHRU_EDGE (test_bb),
3652 df_set_bb_dirty (test_bb);
3653 df_set_bb_dirty (else_bb);
3655 then_bb_index = then_bb->index;
3656 delete_basic_block (then_bb);
3658 /* Make rest of code believe that the newly created block is the THEN_BB
3659 block we removed. */
3662 df_bb_replace (then_bb_index, new_bb);
3663 /* Since the fallthru edge was redirected from test_bb to new_bb,
3664 we need to ensure that new_bb is in the same partition as
3665 test bb (you can not fall through across section boundaries). */
3666 BB_COPY_PARTITION (new_bb, test_bb);
3670 num_updated_if_blocks++;
3675 /* Test for case 2 above. */
3678 find_if_case_2 (basic_block test_bb, edge then_edge, edge else_edge)
3680 basic_block then_bb = then_edge->dest;
3681 basic_block else_bb = else_edge->dest;
3685 /* If we are partitioning hot/cold basic blocks, we don't want to
3686 mess up unconditional or indirect jumps that cross between hot
3689 Basic block partitioning may result in some jumps that appear to
3690 be optimizable (or blocks that appear to be mergeable), but which really
3691 must be left untouched (they are required to make it safely across
3692 partition boundaries). See the comments at the top of
3693 bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */
3695 if ((BB_END (then_bb)
3696 && find_reg_note (BB_END (then_bb), REG_CROSSING_JUMP, NULL_RTX))
3697 || (BB_END (test_bb)
3698 && find_reg_note (BB_END (test_bb), REG_CROSSING_JUMP, NULL_RTX))
3699 || (BB_END (else_bb)
3700 && find_reg_note (BB_END (else_bb), REG_CROSSING_JUMP,
3704 /* ELSE has one successor. */
3705 if (!single_succ_p (else_bb))
3708 else_succ = single_succ_edge (else_bb);
3710 /* ELSE outgoing edge is not complex. */
3711 if (else_succ->flags & EDGE_COMPLEX)
3714 /* ELSE has one predecessor. */
3715 if (!single_pred_p (else_bb))
3718 /* THEN is not EXIT. */
3719 if (then_bb->index < NUM_FIXED_BLOCKS)
3722 /* ELSE is predicted or SUCC(ELSE) postdominates THEN. */
3723 note = find_reg_note (BB_END (test_bb), REG_BR_PROB, NULL_RTX);
3724 if (note && INTVAL (XEXP (note, 0)) >= REG_BR_PROB_BASE / 2)
3726 else if (else_succ->dest->index < NUM_FIXED_BLOCKS
3727 || dominated_by_p (CDI_POST_DOMINATORS, then_bb,
3733 num_possible_if_blocks++;
3736 "\nIF-CASE-2 found, start %d, else %d\n",
3737 test_bb->index, else_bb->index);
3739 /* ELSE is small. */
3740 if (! cheap_bb_rtx_cost_p (else_bb,
3741 COSTS_N_INSNS (BRANCH_COST (optimize_bb_for_speed_p (else_edge->src),
3742 predictable_edge_p (else_edge)))))
3745 /* Registers set are dead, or are predicable. */
3746 if (! dead_or_predicable (test_bb, else_bb, then_bb, else_succ->dest, 0))
3749 /* Conversion went ok, including moving the insns and fixing up the
3750 jump. Adjust the CFG to match. */
3752 df_set_bb_dirty (test_bb);
3753 df_set_bb_dirty (then_bb);
3754 delete_basic_block (else_bb);
3757 num_updated_if_blocks++;
3759 /* ??? We may now fallthru from one of THEN's successors into a join
3760 block. Rerun cleanup_cfg? Examine things manually? Wait? */
3765 /* A subroutine of dead_or_predicable called through for_each_rtx.
3766 Return 1 if a memory is found. */
3769 find_memory (rtx *px, void *data ATTRIBUTE_UNUSED)
3774 /* Used by the code above to perform the actual rtl transformations.
3775 Return TRUE if successful.
3777 TEST_BB is the block containing the conditional branch. MERGE_BB
3778 is the block containing the code to manipulate. NEW_DEST is the
3779 label TEST_BB should be branching to after the conversion.
3780 REVERSEP is true if the sense of the branch should be reversed. */
3783 dead_or_predicable (basic_block test_bb, basic_block merge_bb,
3784 basic_block other_bb, basic_block new_dest, int reversep)
3786 rtx head, end, jump, earliest = NULL_RTX, old_dest, new_label = NULL_RTX;
3787 /* Number of pending changes. */
3788 int n_validated_changes = 0;
3790 jump = BB_END (test_bb);
3792 /* Find the extent of the real code in the merge block. */
3793 head = BB_HEAD (merge_bb);
3794 end = BB_END (merge_bb);
3796 while (DEBUG_INSN_P (end) && end != head)
3797 end = PREV_INSN (end);
3799 /* If merge_bb ends with a tablejump, predicating/moving insn's
3800 into test_bb and then deleting merge_bb will result in the jumptable
3801 that follows merge_bb being removed along with merge_bb and then we
3802 get an unresolved reference to the jumptable. */
3803 if (tablejump_p (end, NULL, NULL))
3807 head = NEXT_INSN (head);
3808 while (DEBUG_INSN_P (head) && head != end)
3809 head = NEXT_INSN (head);
3814 head = end = NULL_RTX;
3817 head = NEXT_INSN (head);
3818 while (DEBUG_INSN_P (head) && head != end)
3819 head = NEXT_INSN (head);
3826 head = end = NULL_RTX;
3829 end = PREV_INSN (end);
3830 while (DEBUG_INSN_P (end) && end != head)
3831 end = PREV_INSN (end);
3834 /* Disable handling dead code by conditional execution if the machine needs
3835 to do anything funny with the tests, etc. */
3836 #ifndef IFCVT_MODIFY_TESTS
3837 if (HAVE_conditional_execution)
3839 /* In the conditional execution case, we have things easy. We know
3840 the condition is reversible. We don't have to check life info
3841 because we're going to conditionally execute the code anyway.
3842 All that's left is making sure the insns involved can actually
3847 cond = cond_exec_get_condition (jump);
3851 prob_val = find_reg_note (jump, REG_BR_PROB, NULL_RTX);
3853 prob_val = XEXP (prob_val, 0);
3857 enum rtx_code rev = reversed_comparison_code (cond, jump);
3860 cond = gen_rtx_fmt_ee (rev, GET_MODE (cond), XEXP (cond, 0),
3863 prob_val = GEN_INT (REG_BR_PROB_BASE - INTVAL (prob_val));
3866 if (cond_exec_process_insns (NULL, head, end, cond, prob_val, 0)
3867 && verify_changes (0))
3868 n_validated_changes = num_validated_changes ();
3875 /* Try the NCE path if the CE path did not result in any changes. */
3876 if (n_validated_changes == 0)
3878 /* In the non-conditional execution case, we have to verify that there
3879 are no trapping operations, no calls, no references to memory, and
3880 that any registers modified are dead at the branch site. */
3882 rtx insn, cond, prev;
3883 bitmap merge_set, test_live, test_set;
3884 unsigned i, fail = 0;
3887 /* Check for no calls or trapping operations. */
3888 for (insn = head; ; insn = NEXT_INSN (insn))
3892 if (NONDEBUG_INSN_P (insn))
3894 if (may_trap_p (PATTERN (insn)))
3897 /* ??? Even non-trapping memories such as stack frame
3898 references must be avoided. For stores, we collect
3899 no lifetime info; for reads, we'd have to assert
3900 true_dependence false against every store in the
3902 if (for_each_rtx (&PATTERN (insn), find_memory, NULL))
3909 if (! any_condjump_p (jump))
3912 /* Find the extent of the conditional. */
3913 cond = noce_get_condition (jump, &earliest, false);
3918 MERGE_SET = set of registers set in MERGE_BB
3919 TEST_LIVE = set of registers live at EARLIEST
3920 TEST_SET = set of registers set between EARLIEST and the
3921 end of the block. */
3923 merge_set = BITMAP_ALLOC (®_obstack);
3924 test_live = BITMAP_ALLOC (®_obstack);
3925 test_set = BITMAP_ALLOC (®_obstack);
3927 /* ??? bb->local_set is only valid during calculate_global_regs_live,
3928 so we must recompute usage for MERGE_BB. Not so bad, I suppose,
3929 since we've already asserted that MERGE_BB is small. */
3930 /* If we allocated new pseudos (e.g. in the conditional move
3931 expander called from noce_emit_cmove), we must resize the
3933 if (max_regno < max_reg_num ())
3934 max_regno = max_reg_num ();
3936 FOR_BB_INSNS (merge_bb, insn)
3938 if (NONDEBUG_INSN_P (insn))
3940 unsigned int uid = INSN_UID (insn);
3942 for (def_rec = DF_INSN_UID_DEFS (uid); *def_rec; def_rec++)
3944 df_ref def = *def_rec;
3945 bitmap_set_bit (merge_set, DF_REF_REGNO (def));
3950 /* For small register class machines, don't lengthen lifetimes of
3951 hard registers before reload. */
3952 if (SMALL_REGISTER_CLASSES && ! reload_completed)
3954 EXECUTE_IF_SET_IN_BITMAP (merge_set, 0, i, bi)
3956 if (i < FIRST_PSEUDO_REGISTER
3958 && ! global_regs[i])
3963 /* For TEST, we're interested in a range of insns, not a whole block.
3964 Moreover, we're interested in the insns live from OTHER_BB. */
3966 /* The loop below takes the set of live registers
3967 after JUMP, and calculates the live set before EARLIEST. */
3968 bitmap_copy (test_live, df_get_live_in (other_bb));
3969 df_simulate_initialize_backwards (test_bb, test_live);
3970 for (insn = jump; ; insn = prev)
3974 df_simulate_find_defs (insn, test_set);
3975 df_simulate_one_insn_backwards (test_bb, insn, test_live);
3977 prev = PREV_INSN (insn);
3978 if (insn == earliest)
3982 /* We can perform the transformation if
3983 MERGE_SET & (TEST_SET | TEST_LIVE)
3985 TEST_SET & DF_LIVE_IN (merge_bb)
3988 if (bitmap_intersect_p (test_set, merge_set)
3989 || bitmap_intersect_p (test_live, merge_set)
3990 || bitmap_intersect_p (test_set, df_get_live_in (merge_bb)))
3993 BITMAP_FREE (merge_set);
3994 BITMAP_FREE (test_live);
3995 BITMAP_FREE (test_set);
4002 /* We don't want to use normal invert_jump or redirect_jump because
4003 we don't want to delete_insn called. Also, we want to do our own
4004 change group management. */
4006 old_dest = JUMP_LABEL (jump);
4007 if (other_bb != new_dest)
4009 new_label = block_label (new_dest);
4011 ? ! invert_jump_1 (jump, new_label)
4012 : ! redirect_jump_1 (jump, new_label))
4016 if (verify_changes (n_validated_changes))
4017 confirm_change_group ();
4021 if (other_bb != new_dest)
4023 redirect_jump_2 (jump, old_dest, new_label, 0, reversep);
4025 redirect_edge_succ (BRANCH_EDGE (test_bb), new_dest);
4028 gcov_type count, probability;
4029 count = BRANCH_EDGE (test_bb)->count;
4030 BRANCH_EDGE (test_bb)->count = FALLTHRU_EDGE (test_bb)->count;
4031 FALLTHRU_EDGE (test_bb)->count = count;
4032 probability = BRANCH_EDGE (test_bb)->probability;
4033 BRANCH_EDGE (test_bb)->probability
4034 = FALLTHRU_EDGE (test_bb)->probability;
4035 FALLTHRU_EDGE (test_bb)->probability = probability;
4036 update_br_prob_note (test_bb);
4040 /* Move the insns out of MERGE_BB to before the branch. */
4045 if (end == BB_END (merge_bb))
4046 BB_END (merge_bb) = PREV_INSN (head);
4048 /* PR 21767: When moving insns above a conditional branch, REG_EQUAL
4049 notes might become invalid. */
4055 if (! INSN_P (insn))
4057 note = find_reg_note (insn, REG_EQUAL, NULL_RTX);
4060 set = single_set (insn);
4061 if (!set || !function_invariant_p (SET_SRC (set)))
4062 remove_note (insn, note);
4063 } while (insn != end && (insn = NEXT_INSN (insn)));
4065 reorder_insns (head, end, PREV_INSN (earliest));
4068 /* Remove the jump and edge if we can. */
4069 if (other_bb == new_dest)
4072 remove_edge (BRANCH_EDGE (test_bb));
4073 /* ??? Can't merge blocks here, as then_bb is still in use.
4074 At minimum, the merge will get done just before bb-reorder. */
4084 /* Main entry point for all if-conversion. */
4094 df_live_add_problem ();
4095 df_live_set_all_dirty ();
4098 num_possible_if_blocks = 0;
4099 num_updated_if_blocks = 0;
4100 num_true_changes = 0;
4102 loop_optimizer_init (AVOID_CFG_MODIFICATIONS);
4103 mark_loop_exit_edges ();
4104 loop_optimizer_finalize ();
4105 free_dominance_info (CDI_DOMINATORS);
4107 /* Compute postdominators. */
4108 calculate_dominance_info (CDI_POST_DOMINATORS);
4110 df_set_flags (DF_LR_RUN_DCE);
4112 /* Go through each of the basic blocks looking for things to convert. If we
4113 have conditional execution, we make multiple passes to allow us to handle
4114 IF-THEN{-ELSE} blocks within other IF-THEN{-ELSE} blocks. */
4119 /* Only need to do dce on the first pass. */
4120 df_clear_flags (DF_LR_RUN_DCE);
4121 cond_exec_changed_p = FALSE;
4124 #ifdef IFCVT_MULTIPLE_DUMPS
4125 if (dump_file && pass > 1)
4126 fprintf (dump_file, "\n\n========== Pass %d ==========\n", pass);
4132 while (!df_get_bb_dirty (bb)
4133 && (new_bb = find_if_header (bb, pass)) != NULL)
4137 #ifdef IFCVT_MULTIPLE_DUMPS
4138 if (dump_file && cond_exec_changed_p)
4139 print_rtl_with_bb (dump_file, get_insns ());
4142 while (cond_exec_changed_p);
4144 #ifdef IFCVT_MULTIPLE_DUMPS
4146 fprintf (dump_file, "\n\n========== no more changes\n");
4149 free_dominance_info (CDI_POST_DOMINATORS);
4154 clear_aux_for_blocks ();
4156 /* If we allocated new pseudos, we must resize the array for sched1. */
4157 if (max_regno < max_reg_num ())
4158 max_regno = max_reg_num ();
4160 /* Write the final stats. */
4161 if (dump_file && num_possible_if_blocks > 0)
4164 "\n%d possible IF blocks searched.\n",
4165 num_possible_if_blocks);
4167 "%d IF blocks converted.\n",
4168 num_updated_if_blocks);
4170 "%d true changes made.\n\n\n",
4175 df_remove_problem (df_live);
4177 #ifdef ENABLE_CHECKING
4178 verify_flow_info ();
4183 gate_handle_if_conversion (void)
4185 return (optimize > 0)
4186 && dbg_cnt (if_conversion);
4189 /* If-conversion and CFG cleanup. */
4191 rest_of_handle_if_conversion (void)
4193 if (flag_if_conversion)
4196 dump_flow_info (dump_file, dump_flags);
4197 cleanup_cfg (CLEANUP_EXPENSIVE);
4205 struct rtl_opt_pass pass_rtl_ifcvt =
4210 gate_handle_if_conversion, /* gate */
4211 rest_of_handle_if_conversion, /* execute */
4214 0, /* static_pass_number */
4215 TV_IFCVT, /* tv_id */
4216 0, /* properties_required */
4217 0, /* properties_provided */
4218 0, /* properties_destroyed */
4219 0, /* todo_flags_start */
4220 TODO_df_finish | TODO_verify_rtl_sharing |
4221 TODO_dump_func /* todo_flags_finish */
4226 gate_handle_if_after_combine (void)
4228 return optimize > 0 && flag_if_conversion
4229 && dbg_cnt (if_after_combine);
4233 /* Rerun if-conversion, as combine may have simplified things enough
4234 to now meet sequence length restrictions. */
4236 rest_of_handle_if_after_combine (void)
4242 struct rtl_opt_pass pass_if_after_combine =
4247 gate_handle_if_after_combine, /* gate */
4248 rest_of_handle_if_after_combine, /* execute */
4251 0, /* static_pass_number */
4252 TV_IFCVT, /* tv_id */
4253 0, /* properties_required */
4254 0, /* properties_provided */
4255 0, /* properties_destroyed */
4256 0, /* todo_flags_start */
4257 TODO_df_finish | TODO_verify_rtl_sharing |
4259 TODO_ggc_collect /* todo_flags_finish */
4265 gate_handle_if_after_reload (void)
4267 return optimize > 0 && flag_if_conversion2
4268 && dbg_cnt (if_after_reload);
4272 rest_of_handle_if_after_reload (void)
4279 struct rtl_opt_pass pass_if_after_reload =
4284 gate_handle_if_after_reload, /* gate */
4285 rest_of_handle_if_after_reload, /* execute */
4288 0, /* static_pass_number */
4289 TV_IFCVT2, /* tv_id */
4290 0, /* properties_required */
4291 0, /* properties_provided */
4292 0, /* properties_destroyed */
4293 0, /* todo_flags_start */
4294 TODO_df_finish | TODO_verify_rtl_sharing |
4296 TODO_ggc_collect /* todo_flags_finish */