1 /* If-conversion support.
2 Copyright (C) 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007
3 Free Software Foundation, Inc.
5 This file is part of GCC.
7 GCC is free software; you can redistribute it and/or modify it
8 under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 3, or (at your option)
12 GCC is distributed in the hope that it will be useful, but WITHOUT
13 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
14 or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public
15 License for more details.
17 You should have received a copy of the GNU General Public License
18 along with GCC; see the file COPYING3. If not see
19 <http://www.gnu.org/licenses/>. */
23 #include "coretypes.h"
30 #include "insn-config.h"
33 #include "hard-reg-set.h"
34 #include "basic-block.h"
44 #include "tree-pass.h"
50 #ifndef HAVE_conditional_execution
51 #define HAVE_conditional_execution 0
53 #ifndef HAVE_conditional_move
54 #define HAVE_conditional_move 0
65 #ifndef HAVE_conditional_trap
66 #define HAVE_conditional_trap 0
69 #ifndef MAX_CONDITIONAL_EXECUTE
70 #define MAX_CONDITIONAL_EXECUTE \
71 (BRANCH_COST (optimize_function_for_speed_p (cfun), false) \
75 #define IFCVT_MULTIPLE_DUMPS 1
77 #define NULL_BLOCK ((basic_block) NULL)
79 /* # of IF-THEN or IF-THEN-ELSE blocks we looked at */
80 static int num_possible_if_blocks;
82 /* # of IF-THEN or IF-THEN-ELSE blocks were converted to conditional
84 static int num_updated_if_blocks;
86 /* # of changes made. */
87 static int num_true_changes;
89 /* Whether conditional execution changes were made. */
90 static int cond_exec_changed_p;
92 /* Forward references. */
93 static int count_bb_insns (const_basic_block);
94 static bool cheap_bb_rtx_cost_p (const_basic_block, int);
95 static rtx first_active_insn (basic_block);
96 static rtx last_active_insn (basic_block, int);
97 static basic_block block_fallthru (basic_block);
98 static int cond_exec_process_insns (ce_if_block_t *, rtx, rtx, rtx, rtx, int);
99 static rtx cond_exec_get_condition (rtx);
100 static rtx noce_get_condition (rtx, rtx *, bool);
101 static int noce_operand_ok (const_rtx);
102 static void merge_if_block (ce_if_block_t *);
103 static int find_cond_trap (basic_block, edge, edge);
104 static basic_block find_if_header (basic_block, int);
105 static int block_jumps_and_fallthru_p (basic_block, basic_block);
106 static int noce_find_if_block (basic_block, edge, edge, int);
107 static int cond_exec_find_if_block (ce_if_block_t *);
108 static int find_if_case_1 (basic_block, edge, edge);
109 static int find_if_case_2 (basic_block, edge, edge);
110 static int find_memory (rtx *, void *);
111 static int dead_or_predicable (basic_block, basic_block, basic_block,
113 static void noce_emit_move_insn (rtx, rtx);
114 static rtx block_has_only_trap (basic_block);
116 /* Count the number of non-jump active insns in BB. */
119 count_bb_insns (const_basic_block bb)
122 rtx insn = BB_HEAD (bb);
126 if (CALL_P (insn) || NONJUMP_INSN_P (insn))
129 if (insn == BB_END (bb))
131 insn = NEXT_INSN (insn);
137 /* Determine whether the total insn_rtx_cost on non-jump insns in
138 basic block BB is less than MAX_COST. This function returns
139 false if the cost of any instruction could not be estimated. */
142 cheap_bb_rtx_cost_p (const_basic_block bb, int max_cost)
145 rtx insn = BB_HEAD (bb);
146 bool speed = optimize_bb_for_speed_p (bb);
150 if (NONJUMP_INSN_P (insn))
152 int cost = insn_rtx_cost (PATTERN (insn), speed);
156 /* If this instruction is the load or set of a "stack" register,
157 such as a floating point register on x87, then the cost of
158 speculatively executing this insn may need to include
159 the additional cost of popping its result off of the
160 register stack. Unfortunately, correctly recognizing and
161 accounting for this additional overhead is tricky, so for
162 now we simply prohibit such speculative execution. */
165 rtx set = single_set (insn);
166 if (set && STACK_REG_P (SET_DEST (set)))
172 if (count >= max_cost)
175 else if (CALL_P (insn))
178 if (insn == BB_END (bb))
180 insn = NEXT_INSN (insn);
186 /* Return the first non-jump active insn in the basic block. */
189 first_active_insn (basic_block bb)
191 rtx insn = BB_HEAD (bb);
195 if (insn == BB_END (bb))
197 insn = NEXT_INSN (insn);
200 while (NOTE_P (insn))
202 if (insn == BB_END (bb))
204 insn = NEXT_INSN (insn);
213 /* Return the last non-jump active (non-jump) insn in the basic block. */
216 last_active_insn (basic_block bb, int skip_use_p)
218 rtx insn = BB_END (bb);
219 rtx head = BB_HEAD (bb);
224 && NONJUMP_INSN_P (insn)
225 && GET_CODE (PATTERN (insn)) == USE))
229 insn = PREV_INSN (insn);
238 /* Return the basic block reached by falling though the basic block BB. */
241 block_fallthru (basic_block bb)
246 FOR_EACH_EDGE (e, ei, bb->succs)
247 if (e->flags & EDGE_FALLTHRU)
250 return (e) ? e->dest : NULL_BLOCK;
253 /* Go through a bunch of insns, converting them to conditional
254 execution format if possible. Return TRUE if all of the non-note
255 insns were processed. */
258 cond_exec_process_insns (ce_if_block_t *ce_info ATTRIBUTE_UNUSED,
259 /* if block information */rtx start,
260 /* first insn to look at */rtx end,
261 /* last insn to look at */rtx test,
262 /* conditional execution test */rtx prob_val,
263 /* probability of branch taken. */int mod_ok)
265 int must_be_last = FALSE;
273 for (insn = start; ; insn = NEXT_INSN (insn))
278 gcc_assert(NONJUMP_INSN_P (insn) || CALL_P (insn));
280 /* Remove USE insns that get in the way. */
281 if (reload_completed && GET_CODE (PATTERN (insn)) == USE)
283 /* ??? Ug. Actually unlinking the thing is problematic,
284 given what we'd have to coordinate with our callers. */
285 SET_INSN_DELETED (insn);
289 /* Last insn wasn't last? */
293 if (modified_in_p (test, insn))
300 /* Now build the conditional form of the instruction. */
301 pattern = PATTERN (insn);
302 xtest = copy_rtx (test);
304 /* If this is already a COND_EXEC, rewrite the test to be an AND of the
306 if (GET_CODE (pattern) == COND_EXEC)
308 if (GET_MODE (xtest) != GET_MODE (COND_EXEC_TEST (pattern)))
311 xtest = gen_rtx_AND (GET_MODE (xtest), xtest,
312 COND_EXEC_TEST (pattern));
313 pattern = COND_EXEC_CODE (pattern);
316 pattern = gen_rtx_COND_EXEC (VOIDmode, xtest, pattern);
318 /* If the machine needs to modify the insn being conditionally executed,
319 say for example to force a constant integer operand into a temp
320 register, do so here. */
321 #ifdef IFCVT_MODIFY_INSN
322 IFCVT_MODIFY_INSN (ce_info, pattern, insn);
327 validate_change (insn, &PATTERN (insn), pattern, 1);
329 if (CALL_P (insn) && prob_val)
330 validate_change (insn, ®_NOTES (insn),
331 alloc_EXPR_LIST (REG_BR_PROB, prob_val,
332 REG_NOTES (insn)), 1);
342 /* Return the condition for a jump. Do not do any special processing. */
345 cond_exec_get_condition (rtx jump)
349 if (any_condjump_p (jump))
350 test_if = SET_SRC (pc_set (jump));
353 cond = XEXP (test_if, 0);
355 /* If this branches to JUMP_LABEL when the condition is false,
356 reverse the condition. */
357 if (GET_CODE (XEXP (test_if, 2)) == LABEL_REF
358 && XEXP (XEXP (test_if, 2), 0) == JUMP_LABEL (jump))
360 enum rtx_code rev = reversed_comparison_code (cond, jump);
364 cond = gen_rtx_fmt_ee (rev, GET_MODE (cond), XEXP (cond, 0),
371 /* Given a simple IF-THEN or IF-THEN-ELSE block, attempt to convert it
372 to conditional execution. Return TRUE if we were successful at
373 converting the block. */
376 cond_exec_process_if_block (ce_if_block_t * ce_info,
377 /* if block information */int do_multiple_p)
379 basic_block test_bb = ce_info->test_bb; /* last test block */
380 basic_block then_bb = ce_info->then_bb; /* THEN */
381 basic_block else_bb = ce_info->else_bb; /* ELSE or NULL */
382 rtx test_expr; /* expression in IF_THEN_ELSE that is tested */
383 rtx then_start; /* first insn in THEN block */
384 rtx then_end; /* last insn + 1 in THEN block */
385 rtx else_start = NULL_RTX; /* first insn in ELSE block or NULL */
386 rtx else_end = NULL_RTX; /* last insn + 1 in ELSE block */
387 int max; /* max # of insns to convert. */
388 int then_mod_ok; /* whether conditional mods are ok in THEN */
389 rtx true_expr; /* test for else block insns */
390 rtx false_expr; /* test for then block insns */
391 rtx true_prob_val; /* probability of else block */
392 rtx false_prob_val; /* probability of then block */
394 enum rtx_code false_code;
396 /* If test is comprised of && or || elements, and we've failed at handling
397 all of them together, just use the last test if it is the special case of
398 && elements without an ELSE block. */
399 if (!do_multiple_p && ce_info->num_multiple_test_blocks)
401 if (else_bb || ! ce_info->and_and_p)
404 ce_info->test_bb = test_bb = ce_info->last_test_bb;
405 ce_info->num_multiple_test_blocks = 0;
406 ce_info->num_and_and_blocks = 0;
407 ce_info->num_or_or_blocks = 0;
410 /* Find the conditional jump to the ELSE or JOIN part, and isolate
412 test_expr = cond_exec_get_condition (BB_END (test_bb));
416 /* If the conditional jump is more than just a conditional jump,
417 then we can not do conditional execution conversion on this block. */
418 if (! onlyjump_p (BB_END (test_bb)))
421 /* Collect the bounds of where we're to search, skipping any labels, jumps
422 and notes at the beginning and end of the block. Then count the total
423 number of insns and see if it is small enough to convert. */
424 then_start = first_active_insn (then_bb);
425 then_end = last_active_insn (then_bb, TRUE);
426 n_insns = ce_info->num_then_insns = count_bb_insns (then_bb);
427 max = MAX_CONDITIONAL_EXECUTE;
432 else_start = first_active_insn (else_bb);
433 else_end = last_active_insn (else_bb, TRUE);
434 n_insns += ce_info->num_else_insns = count_bb_insns (else_bb);
440 /* Map test_expr/test_jump into the appropriate MD tests to use on
441 the conditionally executed code. */
443 true_expr = test_expr;
445 false_code = reversed_comparison_code (true_expr, BB_END (test_bb));
446 if (false_code != UNKNOWN)
447 false_expr = gen_rtx_fmt_ee (false_code, GET_MODE (true_expr),
448 XEXP (true_expr, 0), XEXP (true_expr, 1));
450 false_expr = NULL_RTX;
452 #ifdef IFCVT_MODIFY_TESTS
453 /* If the machine description needs to modify the tests, such as setting a
454 conditional execution register from a comparison, it can do so here. */
455 IFCVT_MODIFY_TESTS (ce_info, true_expr, false_expr);
457 /* See if the conversion failed. */
458 if (!true_expr || !false_expr)
462 true_prob_val = find_reg_note (BB_END (test_bb), REG_BR_PROB, NULL_RTX);
465 true_prob_val = XEXP (true_prob_val, 0);
466 false_prob_val = GEN_INT (REG_BR_PROB_BASE - INTVAL (true_prob_val));
469 false_prob_val = NULL_RTX;
471 /* If we have && or || tests, do them here. These tests are in the adjacent
472 blocks after the first block containing the test. */
473 if (ce_info->num_multiple_test_blocks > 0)
475 basic_block bb = test_bb;
476 basic_block last_test_bb = ce_info->last_test_bb;
485 enum rtx_code f_code;
487 bb = block_fallthru (bb);
488 start = first_active_insn (bb);
489 end = last_active_insn (bb, TRUE);
491 && ! cond_exec_process_insns (ce_info, start, end, false_expr,
492 false_prob_val, FALSE))
495 /* If the conditional jump is more than just a conditional jump, then
496 we can not do conditional execution conversion on this block. */
497 if (! onlyjump_p (BB_END (bb)))
500 /* Find the conditional jump and isolate the test. */
501 t = cond_exec_get_condition (BB_END (bb));
505 f_code = reversed_comparison_code (t, BB_END (bb));
506 if (f_code == UNKNOWN)
509 f = gen_rtx_fmt_ee (f_code, GET_MODE (t), XEXP (t, 0), XEXP (t, 1));
510 if (ce_info->and_and_p)
512 t = gen_rtx_AND (GET_MODE (t), true_expr, t);
513 f = gen_rtx_IOR (GET_MODE (t), false_expr, f);
517 t = gen_rtx_IOR (GET_MODE (t), true_expr, t);
518 f = gen_rtx_AND (GET_MODE (t), false_expr, f);
521 /* If the machine description needs to modify the tests, such as
522 setting a conditional execution register from a comparison, it can
524 #ifdef IFCVT_MODIFY_MULTIPLE_TESTS
525 IFCVT_MODIFY_MULTIPLE_TESTS (ce_info, bb, t, f);
527 /* See if the conversion failed. */
535 while (bb != last_test_bb);
538 /* For IF-THEN-ELSE blocks, we don't allow modifications of the test
539 on then THEN block. */
540 then_mod_ok = (else_bb == NULL_BLOCK);
542 /* Go through the THEN and ELSE blocks converting the insns if possible
543 to conditional execution. */
547 || ! cond_exec_process_insns (ce_info, then_start, then_end,
548 false_expr, false_prob_val,
552 if (else_bb && else_end
553 && ! cond_exec_process_insns (ce_info, else_start, else_end,
554 true_expr, true_prob_val, TRUE))
557 /* If we cannot apply the changes, fail. Do not go through the normal fail
558 processing, since apply_change_group will call cancel_changes. */
559 if (! apply_change_group ())
561 #ifdef IFCVT_MODIFY_CANCEL
562 /* Cancel any machine dependent changes. */
563 IFCVT_MODIFY_CANCEL (ce_info);
568 #ifdef IFCVT_MODIFY_FINAL
569 /* Do any machine dependent final modifications. */
570 IFCVT_MODIFY_FINAL (ce_info);
573 /* Conversion succeeded. */
575 fprintf (dump_file, "%d insn%s converted to conditional execution.\n",
576 n_insns, (n_insns == 1) ? " was" : "s were");
578 /* Merge the blocks! */
579 merge_if_block (ce_info);
580 cond_exec_changed_p = TRUE;
584 #ifdef IFCVT_MODIFY_CANCEL
585 /* Cancel any machine dependent changes. */
586 IFCVT_MODIFY_CANCEL (ce_info);
593 /* Used by noce_process_if_block to communicate with its subroutines.
595 The subroutines know that A and B may be evaluated freely. They
596 know that X is a register. They should insert new instructions
597 before cond_earliest. */
601 /* The basic blocks that make up the IF-THEN-{ELSE-,}JOIN block. */
602 basic_block test_bb, then_bb, else_bb, join_bb;
604 /* The jump that ends TEST_BB. */
607 /* The jump condition. */
610 /* New insns should be inserted before this one. */
613 /* Insns in the THEN and ELSE block. There is always just this
614 one insns in those blocks. The insns are single_set insns.
615 If there was no ELSE block, INSN_B is the last insn before
616 COND_EARLIEST, or NULL_RTX. In the former case, the insn
617 operands are still valid, as if INSN_B was moved down below
621 /* The SET_SRC of INSN_A and INSN_B. */
624 /* The SET_DEST of INSN_A. */
627 /* True if this if block is not canonical. In the canonical form of
628 if blocks, the THEN_BB is the block reached via the fallthru edge
629 from TEST_BB. For the noce transformations, we allow the symmetric
631 bool then_else_reversed;
633 /* Estimated cost of the particular branch instruction. */
637 static rtx noce_emit_store_flag (struct noce_if_info *, rtx, int, int);
638 static int noce_try_move (struct noce_if_info *);
639 static int noce_try_store_flag (struct noce_if_info *);
640 static int noce_try_addcc (struct noce_if_info *);
641 static int noce_try_store_flag_constants (struct noce_if_info *);
642 static int noce_try_store_flag_mask (struct noce_if_info *);
643 static rtx noce_emit_cmove (struct noce_if_info *, rtx, enum rtx_code, rtx,
645 static int noce_try_cmove (struct noce_if_info *);
646 static int noce_try_cmove_arith (struct noce_if_info *);
647 static rtx noce_get_alt_condition (struct noce_if_info *, rtx, rtx *);
648 static int noce_try_minmax (struct noce_if_info *);
649 static int noce_try_abs (struct noce_if_info *);
650 static int noce_try_sign_mask (struct noce_if_info *);
652 /* Helper function for noce_try_store_flag*. */
655 noce_emit_store_flag (struct noce_if_info *if_info, rtx x, int reversep,
658 rtx cond = if_info->cond;
662 cond_complex = (! general_operand (XEXP (cond, 0), VOIDmode)
663 || ! general_operand (XEXP (cond, 1), VOIDmode));
665 /* If earliest == jump, or when the condition is complex, try to
666 build the store_flag insn directly. */
669 cond = XEXP (SET_SRC (pc_set (if_info->jump)), 0);
672 code = reversed_comparison_code (cond, if_info->jump);
674 code = GET_CODE (cond);
676 if ((if_info->cond_earliest == if_info->jump || cond_complex)
677 && (normalize == 0 || STORE_FLAG_VALUE == normalize))
681 tmp = gen_rtx_fmt_ee (code, GET_MODE (x), XEXP (cond, 0),
683 tmp = gen_rtx_SET (VOIDmode, x, tmp);
686 tmp = emit_insn (tmp);
688 if (recog_memoized (tmp) >= 0)
694 if_info->cond_earliest = if_info->jump;
702 /* Don't even try if the comparison operands or the mode of X are weird. */
703 if (cond_complex || !SCALAR_INT_MODE_P (GET_MODE (x)))
706 return emit_store_flag (x, code, XEXP (cond, 0),
707 XEXP (cond, 1), VOIDmode,
708 (code == LTU || code == LEU
709 || code == GEU || code == GTU), normalize);
712 /* Emit instruction to move an rtx, possibly into STRICT_LOW_PART.
713 X is the destination/target and Y is the value to copy. */
716 noce_emit_move_insn (rtx x, rtx y)
718 enum machine_mode outmode;
722 if (GET_CODE (x) != STRICT_LOW_PART)
724 rtx seq, insn, target;
728 /* Check that the SET_SRC is reasonable before calling emit_move_insn,
729 otherwise construct a suitable SET pattern ourselves. */
730 insn = (OBJECT_P (y) || CONSTANT_P (y) || GET_CODE (y) == SUBREG)
731 ? emit_move_insn (x, y)
732 : emit_insn (gen_rtx_SET (VOIDmode, x, y));
736 if (recog_memoized (insn) <= 0)
738 if (GET_CODE (x) == ZERO_EXTRACT)
740 rtx op = XEXP (x, 0);
741 unsigned HOST_WIDE_INT size = INTVAL (XEXP (x, 1));
742 unsigned HOST_WIDE_INT start = INTVAL (XEXP (x, 2));
744 /* store_bit_field expects START to be relative to
745 BYTES_BIG_ENDIAN and adjusts this value for machines with
746 BITS_BIG_ENDIAN != BYTES_BIG_ENDIAN. In order to be able to
747 invoke store_bit_field again it is necessary to have the START
748 value from the first call. */
749 if (BITS_BIG_ENDIAN != BYTES_BIG_ENDIAN)
752 start = BITS_PER_UNIT - start - size;
755 gcc_assert (REG_P (op));
756 start = BITS_PER_WORD - start - size;
760 gcc_assert (start < (MEM_P (op) ? BITS_PER_UNIT : BITS_PER_WORD));
761 store_bit_field (op, size, start, GET_MODE (x), y);
765 switch (GET_RTX_CLASS (GET_CODE (y)))
768 ot = code_to_optab[GET_CODE (y)];
772 target = expand_unop (GET_MODE (y), ot, XEXP (y, 0), x, 0);
773 if (target != NULL_RTX)
776 emit_move_insn (x, target);
785 ot = code_to_optab[GET_CODE (y)];
789 target = expand_binop (GET_MODE (y), ot,
790 XEXP (y, 0), XEXP (y, 1),
792 if (target != NULL_RTX)
795 emit_move_insn (x, target);
812 inner = XEXP (outer, 0);
813 outmode = GET_MODE (outer);
814 bitpos = SUBREG_BYTE (outer) * BITS_PER_UNIT;
815 store_bit_field (inner, GET_MODE_BITSIZE (outmode), bitpos, outmode, y);
818 /* Return sequence of instructions generated by if conversion. This
819 function calls end_sequence() to end the current stream, ensures
820 that are instructions are unshared, recognizable non-jump insns.
821 On failure, this function returns a NULL_RTX. */
824 end_ifcvt_sequence (struct noce_if_info *if_info)
827 rtx seq = get_insns ();
829 set_used_flags (if_info->x);
830 set_used_flags (if_info->cond);
831 unshare_all_rtl_in_chain (seq);
834 /* Make sure that all of the instructions emitted are recognizable,
835 and that we haven't introduced a new jump instruction.
836 As an exercise for the reader, build a general mechanism that
837 allows proper placement of required clobbers. */
838 for (insn = seq; insn; insn = NEXT_INSN (insn))
840 || recog_memoized (insn) == -1)
846 /* Convert "if (a != b) x = a; else x = b" into "x = a" and
847 "if (a == b) x = a; else x = b" into "x = b". */
850 noce_try_move (struct noce_if_info *if_info)
852 rtx cond = if_info->cond;
853 enum rtx_code code = GET_CODE (cond);
856 if (code != NE && code != EQ)
859 /* This optimization isn't valid if either A or B could be a NaN
861 if (HONOR_NANS (GET_MODE (if_info->x))
862 || HONOR_SIGNED_ZEROS (GET_MODE (if_info->x)))
865 /* Check whether the operands of the comparison are A and in
867 if ((rtx_equal_p (if_info->a, XEXP (cond, 0))
868 && rtx_equal_p (if_info->b, XEXP (cond, 1)))
869 || (rtx_equal_p (if_info->a, XEXP (cond, 1))
870 && rtx_equal_p (if_info->b, XEXP (cond, 0))))
872 y = (code == EQ) ? if_info->a : if_info->b;
874 /* Avoid generating the move if the source is the destination. */
875 if (! rtx_equal_p (if_info->x, y))
878 noce_emit_move_insn (if_info->x, y);
879 seq = end_ifcvt_sequence (if_info);
883 emit_insn_before_setloc (seq, if_info->jump,
884 INSN_LOCATOR (if_info->insn_a));
891 /* Convert "if (test) x = 1; else x = 0".
893 Only try 0 and STORE_FLAG_VALUE here. Other combinations will be
894 tried in noce_try_store_flag_constants after noce_try_cmove has had
895 a go at the conversion. */
898 noce_try_store_flag (struct noce_if_info *if_info)
903 if (GET_CODE (if_info->b) == CONST_INT
904 && INTVAL (if_info->b) == STORE_FLAG_VALUE
905 && if_info->a == const0_rtx)
907 else if (if_info->b == const0_rtx
908 && GET_CODE (if_info->a) == CONST_INT
909 && INTVAL (if_info->a) == STORE_FLAG_VALUE
910 && (reversed_comparison_code (if_info->cond, if_info->jump)
918 target = noce_emit_store_flag (if_info, if_info->x, reversep, 0);
921 if (target != if_info->x)
922 noce_emit_move_insn (if_info->x, target);
924 seq = end_ifcvt_sequence (if_info);
928 emit_insn_before_setloc (seq, if_info->jump,
929 INSN_LOCATOR (if_info->insn_a));
939 /* Convert "if (test) x = a; else x = b", for A and B constant. */
942 noce_try_store_flag_constants (struct noce_if_info *if_info)
946 HOST_WIDE_INT itrue, ifalse, diff, tmp;
947 int normalize, can_reverse;
948 enum machine_mode mode;
950 if (GET_CODE (if_info->a) == CONST_INT
951 && GET_CODE (if_info->b) == CONST_INT)
953 mode = GET_MODE (if_info->x);
954 ifalse = INTVAL (if_info->a);
955 itrue = INTVAL (if_info->b);
957 /* Make sure we can represent the difference between the two values. */
958 if ((itrue - ifalse > 0)
959 != ((ifalse < 0) != (itrue < 0) ? ifalse < 0 : ifalse < itrue))
962 diff = trunc_int_for_mode (itrue - ifalse, mode);
964 can_reverse = (reversed_comparison_code (if_info->cond, if_info->jump)
968 if (diff == STORE_FLAG_VALUE || diff == -STORE_FLAG_VALUE)
970 else if (ifalse == 0 && exact_log2 (itrue) >= 0
971 && (STORE_FLAG_VALUE == 1
972 || if_info->branch_cost >= 2))
974 else if (itrue == 0 && exact_log2 (ifalse) >= 0 && can_reverse
975 && (STORE_FLAG_VALUE == 1 || if_info->branch_cost >= 2))
976 normalize = 1, reversep = 1;
978 && (STORE_FLAG_VALUE == -1
979 || if_info->branch_cost >= 2))
981 else if (ifalse == -1 && can_reverse
982 && (STORE_FLAG_VALUE == -1 || if_info->branch_cost >= 2))
983 normalize = -1, reversep = 1;
984 else if ((if_info->branch_cost >= 2 && STORE_FLAG_VALUE == -1)
985 || if_info->branch_cost >= 3)
992 tmp = itrue; itrue = ifalse; ifalse = tmp;
993 diff = trunc_int_for_mode (-diff, mode);
997 target = noce_emit_store_flag (if_info, if_info->x, reversep, normalize);
1004 /* if (test) x = 3; else x = 4;
1005 => x = 3 + (test == 0); */
1006 if (diff == STORE_FLAG_VALUE || diff == -STORE_FLAG_VALUE)
1008 target = expand_simple_binop (mode,
1009 (diff == STORE_FLAG_VALUE
1011 GEN_INT (ifalse), target, if_info->x, 0,
1015 /* if (test) x = 8; else x = 0;
1016 => x = (test != 0) << 3; */
1017 else if (ifalse == 0 && (tmp = exact_log2 (itrue)) >= 0)
1019 target = expand_simple_binop (mode, ASHIFT,
1020 target, GEN_INT (tmp), if_info->x, 0,
1024 /* if (test) x = -1; else x = b;
1025 => x = -(test != 0) | b; */
1026 else if (itrue == -1)
1028 target = expand_simple_binop (mode, IOR,
1029 target, GEN_INT (ifalse), if_info->x, 0,
1033 /* if (test) x = a; else x = b;
1034 => x = (-(test != 0) & (b - a)) + a; */
1037 target = expand_simple_binop (mode, AND,
1038 target, GEN_INT (diff), if_info->x, 0,
1041 target = expand_simple_binop (mode, PLUS,
1042 target, GEN_INT (ifalse),
1043 if_info->x, 0, OPTAB_WIDEN);
1052 if (target != if_info->x)
1053 noce_emit_move_insn (if_info->x, target);
1055 seq = end_ifcvt_sequence (if_info);
1059 emit_insn_before_setloc (seq, if_info->jump,
1060 INSN_LOCATOR (if_info->insn_a));
1067 /* Convert "if (test) foo++" into "foo += (test != 0)", and
1068 similarly for "foo--". */
1071 noce_try_addcc (struct noce_if_info *if_info)
1074 int subtract, normalize;
1076 if (GET_CODE (if_info->a) == PLUS
1077 && rtx_equal_p (XEXP (if_info->a, 0), if_info->b)
1078 && (reversed_comparison_code (if_info->cond, if_info->jump)
1081 rtx cond = if_info->cond;
1082 enum rtx_code code = reversed_comparison_code (cond, if_info->jump);
1084 /* First try to use addcc pattern. */
1085 if (general_operand (XEXP (cond, 0), VOIDmode)
1086 && general_operand (XEXP (cond, 1), VOIDmode))
1089 target = emit_conditional_add (if_info->x, code,
1094 XEXP (if_info->a, 1),
1095 GET_MODE (if_info->x),
1096 (code == LTU || code == GEU
1097 || code == LEU || code == GTU));
1100 if (target != if_info->x)
1101 noce_emit_move_insn (if_info->x, target);
1103 seq = end_ifcvt_sequence (if_info);
1107 emit_insn_before_setloc (seq, if_info->jump,
1108 INSN_LOCATOR (if_info->insn_a));
1114 /* If that fails, construct conditional increment or decrement using
1116 if (if_info->branch_cost >= 2
1117 && (XEXP (if_info->a, 1) == const1_rtx
1118 || XEXP (if_info->a, 1) == constm1_rtx))
1121 if (STORE_FLAG_VALUE == INTVAL (XEXP (if_info->a, 1)))
1122 subtract = 0, normalize = 0;
1123 else if (-STORE_FLAG_VALUE == INTVAL (XEXP (if_info->a, 1)))
1124 subtract = 1, normalize = 0;
1126 subtract = 0, normalize = INTVAL (XEXP (if_info->a, 1));
1129 target = noce_emit_store_flag (if_info,
1130 gen_reg_rtx (GET_MODE (if_info->x)),
1134 target = expand_simple_binop (GET_MODE (if_info->x),
1135 subtract ? MINUS : PLUS,
1136 if_info->b, target, if_info->x,
1140 if (target != if_info->x)
1141 noce_emit_move_insn (if_info->x, target);
1143 seq = end_ifcvt_sequence (if_info);
1147 emit_insn_before_setloc (seq, if_info->jump,
1148 INSN_LOCATOR (if_info->insn_a));
1158 /* Convert "if (test) x = 0;" to "x &= -(test == 0);" */
1161 noce_try_store_flag_mask (struct noce_if_info *if_info)
1167 if ((if_info->branch_cost >= 2
1168 || STORE_FLAG_VALUE == -1)
1169 && ((if_info->a == const0_rtx
1170 && rtx_equal_p (if_info->b, if_info->x))
1171 || ((reversep = (reversed_comparison_code (if_info->cond,
1174 && if_info->b == const0_rtx
1175 && rtx_equal_p (if_info->a, if_info->x))))
1178 target = noce_emit_store_flag (if_info,
1179 gen_reg_rtx (GET_MODE (if_info->x)),
1182 target = expand_simple_binop (GET_MODE (if_info->x), AND,
1184 target, if_info->x, 0,
1189 if (target != if_info->x)
1190 noce_emit_move_insn (if_info->x, target);
1192 seq = end_ifcvt_sequence (if_info);
1196 emit_insn_before_setloc (seq, if_info->jump,
1197 INSN_LOCATOR (if_info->insn_a));
1207 /* Helper function for noce_try_cmove and noce_try_cmove_arith. */
1210 noce_emit_cmove (struct noce_if_info *if_info, rtx x, enum rtx_code code,
1211 rtx cmp_a, rtx cmp_b, rtx vfalse, rtx vtrue)
1213 /* If earliest == jump, try to build the cmove insn directly.
1214 This is helpful when combine has created some complex condition
1215 (like for alpha's cmovlbs) that we can't hope to regenerate
1216 through the normal interface. */
1218 if (if_info->cond_earliest == if_info->jump)
1222 tmp = gen_rtx_fmt_ee (code, GET_MODE (if_info->cond), cmp_a, cmp_b);
1223 tmp = gen_rtx_IF_THEN_ELSE (GET_MODE (x), tmp, vtrue, vfalse);
1224 tmp = gen_rtx_SET (VOIDmode, x, tmp);
1227 tmp = emit_insn (tmp);
1229 if (recog_memoized (tmp) >= 0)
1241 /* Don't even try if the comparison operands are weird. */
1242 if (! general_operand (cmp_a, GET_MODE (cmp_a))
1243 || ! general_operand (cmp_b, GET_MODE (cmp_b)))
1246 #if HAVE_conditional_move
1247 return emit_conditional_move (x, code, cmp_a, cmp_b, VOIDmode,
1248 vtrue, vfalse, GET_MODE (x),
1249 (code == LTU || code == GEU
1250 || code == LEU || code == GTU));
1252 /* We'll never get here, as noce_process_if_block doesn't call the
1253 functions involved. Ifdef code, however, should be discouraged
1254 because it leads to typos in the code not selected. However,
1255 emit_conditional_move won't exist either. */
1260 /* Try only simple constants and registers here. More complex cases
1261 are handled in noce_try_cmove_arith after noce_try_store_flag_arith
1262 has had a go at it. */
1265 noce_try_cmove (struct noce_if_info *if_info)
1270 if ((CONSTANT_P (if_info->a) || register_operand (if_info->a, VOIDmode))
1271 && (CONSTANT_P (if_info->b) || register_operand (if_info->b, VOIDmode)))
1275 code = GET_CODE (if_info->cond);
1276 target = noce_emit_cmove (if_info, if_info->x, code,
1277 XEXP (if_info->cond, 0),
1278 XEXP (if_info->cond, 1),
1279 if_info->a, if_info->b);
1283 if (target != if_info->x)
1284 noce_emit_move_insn (if_info->x, target);
1286 seq = end_ifcvt_sequence (if_info);
1290 emit_insn_before_setloc (seq, if_info->jump,
1291 INSN_LOCATOR (if_info->insn_a));
1304 /* Try more complex cases involving conditional_move. */
1307 noce_try_cmove_arith (struct noce_if_info *if_info)
1319 /* A conditional move from two memory sources is equivalent to a
1320 conditional on their addresses followed by a load. Don't do this
1321 early because it'll screw alias analysis. Note that we've
1322 already checked for no side effects. */
1323 /* ??? FIXME: Magic number 5. */
1324 if (cse_not_expected
1325 && MEM_P (a) && MEM_P (b)
1326 && if_info->branch_cost >= 5)
1330 x = gen_reg_rtx (Pmode);
1334 /* ??? We could handle this if we knew that a load from A or B could
1335 not fault. This is also true if we've already loaded
1336 from the address along the path from ENTRY. */
1337 else if (may_trap_p (a) || may_trap_p (b))
1340 /* if (test) x = a + b; else x = c - d;
1347 code = GET_CODE (if_info->cond);
1348 insn_a = if_info->insn_a;
1349 insn_b = if_info->insn_b;
1351 /* Total insn_rtx_cost should be smaller than branch cost. Exit
1352 if insn_rtx_cost can't be estimated. */
1355 insn_cost = insn_rtx_cost (PATTERN (insn_a),
1356 optimize_bb_for_speed_p (BLOCK_FOR_INSN (insn_a)));
1357 if (insn_cost == 0 || insn_cost > COSTS_N_INSNS (if_info->branch_cost))
1365 insn_cost += insn_rtx_cost (PATTERN (insn_b),
1366 optimize_bb_for_speed_p (BLOCK_FOR_INSN (insn_b)));
1367 if (insn_cost == 0 || insn_cost > COSTS_N_INSNS (if_info->branch_cost))
1371 /* Possibly rearrange operands to make things come out more natural. */
1372 if (reversed_comparison_code (if_info->cond, if_info->jump) != UNKNOWN)
1375 if (rtx_equal_p (b, x))
1377 else if (general_operand (b, GET_MODE (b)))
1382 code = reversed_comparison_code (if_info->cond, if_info->jump);
1383 tmp = a, a = b, b = tmp;
1384 tmp = insn_a, insn_a = insn_b, insn_b = tmp;
1393 /* If either operand is complex, load it into a register first.
1394 The best way to do this is to copy the original insn. In this
1395 way we preserve any clobbers etc that the insn may have had.
1396 This is of course not possible in the IS_MEM case. */
1397 if (! general_operand (a, GET_MODE (a)))
1403 tmp = gen_reg_rtx (GET_MODE (a));
1404 tmp = emit_insn (gen_rtx_SET (VOIDmode, tmp, a));
1407 goto end_seq_and_fail;
1410 a = gen_reg_rtx (GET_MODE (a));
1411 tmp = copy_rtx (insn_a);
1412 set = single_set (tmp);
1414 tmp = emit_insn (PATTERN (tmp));
1416 if (recog_memoized (tmp) < 0)
1417 goto end_seq_and_fail;
1419 if (! general_operand (b, GET_MODE (b)))
1425 tmp = gen_reg_rtx (GET_MODE (b));
1426 tmp = gen_rtx_SET (VOIDmode, tmp, b);
1429 goto end_seq_and_fail;
1432 b = gen_reg_rtx (GET_MODE (b));
1433 tmp = copy_rtx (insn_b);
1434 set = single_set (tmp);
1436 tmp = PATTERN (tmp);
1439 /* If insn to set up A clobbers any registers B depends on, try to
1440 swap insn that sets up A with the one that sets up B. If even
1441 that doesn't help, punt. */
1442 last = get_last_insn ();
1443 if (last && modified_in_p (orig_b, last))
1445 tmp = emit_insn_before (tmp, get_insns ());
1446 if (modified_in_p (orig_a, tmp))
1447 goto end_seq_and_fail;
1450 tmp = emit_insn (tmp);
1452 if (recog_memoized (tmp) < 0)
1453 goto end_seq_and_fail;
1456 target = noce_emit_cmove (if_info, x, code, XEXP (if_info->cond, 0),
1457 XEXP (if_info->cond, 1), a, b);
1460 goto end_seq_and_fail;
1462 /* If we're handling a memory for above, emit the load now. */
1465 tmp = gen_rtx_MEM (GET_MODE (if_info->x), target);
1467 /* Copy over flags as appropriate. */
1468 if (MEM_VOLATILE_P (if_info->a) || MEM_VOLATILE_P (if_info->b))
1469 MEM_VOLATILE_P (tmp) = 1;
1470 if (MEM_IN_STRUCT_P (if_info->a) && MEM_IN_STRUCT_P (if_info->b))
1471 MEM_IN_STRUCT_P (tmp) = 1;
1472 if (MEM_SCALAR_P (if_info->a) && MEM_SCALAR_P (if_info->b))
1473 MEM_SCALAR_P (tmp) = 1;
1474 if (MEM_ALIAS_SET (if_info->a) == MEM_ALIAS_SET (if_info->b))
1475 set_mem_alias_set (tmp, MEM_ALIAS_SET (if_info->a));
1477 MIN (MEM_ALIGN (if_info->a), MEM_ALIGN (if_info->b)));
1479 noce_emit_move_insn (if_info->x, tmp);
1481 else if (target != x)
1482 noce_emit_move_insn (x, target);
1484 tmp = end_ifcvt_sequence (if_info);
1488 emit_insn_before_setloc (tmp, if_info->jump, INSN_LOCATOR (if_info->insn_a));
1496 /* For most cases, the simplified condition we found is the best
1497 choice, but this is not the case for the min/max/abs transforms.
1498 For these we wish to know that it is A or B in the condition. */
1501 noce_get_alt_condition (struct noce_if_info *if_info, rtx target,
1504 rtx cond, set, insn;
1507 /* If target is already mentioned in the known condition, return it. */
1508 if (reg_mentioned_p (target, if_info->cond))
1510 *earliest = if_info->cond_earliest;
1511 return if_info->cond;
1514 set = pc_set (if_info->jump);
1515 cond = XEXP (SET_SRC (set), 0);
1517 = GET_CODE (XEXP (SET_SRC (set), 2)) == LABEL_REF
1518 && XEXP (XEXP (SET_SRC (set), 2), 0) == JUMP_LABEL (if_info->jump);
1519 if (if_info->then_else_reversed)
1522 /* If we're looking for a constant, try to make the conditional
1523 have that constant in it. There are two reasons why it may
1524 not have the constant we want:
1526 1. GCC may have needed to put the constant in a register, because
1527 the target can't compare directly against that constant. For
1528 this case, we look for a SET immediately before the comparison
1529 that puts a constant in that register.
1531 2. GCC may have canonicalized the conditional, for example
1532 replacing "if x < 4" with "if x <= 3". We can undo that (or
1533 make equivalent types of changes) to get the constants we need
1534 if they're off by one in the right direction. */
1536 if (GET_CODE (target) == CONST_INT)
1538 enum rtx_code code = GET_CODE (if_info->cond);
1539 rtx op_a = XEXP (if_info->cond, 0);
1540 rtx op_b = XEXP (if_info->cond, 1);
1543 /* First, look to see if we put a constant in a register. */
1544 prev_insn = prev_nonnote_insn (if_info->cond_earliest);
1546 && BLOCK_NUM (prev_insn) == BLOCK_NUM (if_info->cond_earliest)
1547 && INSN_P (prev_insn)
1548 && GET_CODE (PATTERN (prev_insn)) == SET)
1550 rtx src = find_reg_equal_equiv_note (prev_insn);
1552 src = SET_SRC (PATTERN (prev_insn));
1553 if (GET_CODE (src) == CONST_INT)
1555 if (rtx_equal_p (op_a, SET_DEST (PATTERN (prev_insn))))
1557 else if (rtx_equal_p (op_b, SET_DEST (PATTERN (prev_insn))))
1560 if (GET_CODE (op_a) == CONST_INT)
1565 code = swap_condition (code);
1570 /* Now, look to see if we can get the right constant by
1571 adjusting the conditional. */
1572 if (GET_CODE (op_b) == CONST_INT)
1574 HOST_WIDE_INT desired_val = INTVAL (target);
1575 HOST_WIDE_INT actual_val = INTVAL (op_b);
1580 if (actual_val == desired_val + 1)
1583 op_b = GEN_INT (desired_val);
1587 if (actual_val == desired_val - 1)
1590 op_b = GEN_INT (desired_val);
1594 if (actual_val == desired_val - 1)
1597 op_b = GEN_INT (desired_val);
1601 if (actual_val == desired_val + 1)
1604 op_b = GEN_INT (desired_val);
1612 /* If we made any changes, generate a new conditional that is
1613 equivalent to what we started with, but has the right
1615 if (code != GET_CODE (if_info->cond)
1616 || op_a != XEXP (if_info->cond, 0)
1617 || op_b != XEXP (if_info->cond, 1))
1619 cond = gen_rtx_fmt_ee (code, GET_MODE (cond), op_a, op_b);
1620 *earliest = if_info->cond_earliest;
1625 cond = canonicalize_condition (if_info->jump, cond, reverse,
1626 earliest, target, false, true);
1627 if (! cond || ! reg_mentioned_p (target, cond))
1630 /* We almost certainly searched back to a different place.
1631 Need to re-verify correct lifetimes. */
1633 /* X may not be mentioned in the range (cond_earliest, jump]. */
1634 for (insn = if_info->jump; insn != *earliest; insn = PREV_INSN (insn))
1635 if (INSN_P (insn) && reg_overlap_mentioned_p (if_info->x, PATTERN (insn)))
1638 /* A and B may not be modified in the range [cond_earliest, jump). */
1639 for (insn = *earliest; insn != if_info->jump; insn = NEXT_INSN (insn))
1641 && (modified_in_p (if_info->a, insn)
1642 || modified_in_p (if_info->b, insn)))
1648 /* Convert "if (a < b) x = a; else x = b;" to "x = min(a, b);", etc. */
1651 noce_try_minmax (struct noce_if_info *if_info)
1653 rtx cond, earliest, target, seq;
1654 enum rtx_code code, op;
1657 /* ??? Reject modes with NaNs or signed zeros since we don't know how
1658 they will be resolved with an SMIN/SMAX. It wouldn't be too hard
1659 to get the target to tell us... */
1660 if (HONOR_SIGNED_ZEROS (GET_MODE (if_info->x))
1661 || HONOR_NANS (GET_MODE (if_info->x)))
1664 cond = noce_get_alt_condition (if_info, if_info->a, &earliest);
1668 /* Verify the condition is of the form we expect, and canonicalize
1669 the comparison code. */
1670 code = GET_CODE (cond);
1671 if (rtx_equal_p (XEXP (cond, 0), if_info->a))
1673 if (! rtx_equal_p (XEXP (cond, 1), if_info->b))
1676 else if (rtx_equal_p (XEXP (cond, 1), if_info->a))
1678 if (! rtx_equal_p (XEXP (cond, 0), if_info->b))
1680 code = swap_condition (code);
1685 /* Determine what sort of operation this is. Note that the code is for
1686 a taken branch, so the code->operation mapping appears backwards. */
1719 target = expand_simple_binop (GET_MODE (if_info->x), op,
1720 if_info->a, if_info->b,
1721 if_info->x, unsignedp, OPTAB_WIDEN);
1727 if (target != if_info->x)
1728 noce_emit_move_insn (if_info->x, target);
1730 seq = end_ifcvt_sequence (if_info);
1734 emit_insn_before_setloc (seq, if_info->jump, INSN_LOCATOR (if_info->insn_a));
1735 if_info->cond = cond;
1736 if_info->cond_earliest = earliest;
1741 /* Convert "if (a < 0) x = -a; else x = a;" to "x = abs(a);", etc. */
1744 noce_try_abs (struct noce_if_info *if_info)
1746 rtx cond, earliest, target, seq, a, b, c;
1749 /* Reject modes with signed zeros. */
1750 if (HONOR_SIGNED_ZEROS (GET_MODE (if_info->x)))
1753 /* Recognize A and B as constituting an ABS or NABS. The canonical
1754 form is a branch around the negation, taken when the object is the
1755 first operand of a comparison against 0 that evaluates to true. */
1758 if (GET_CODE (a) == NEG && rtx_equal_p (XEXP (a, 0), b))
1760 else if (GET_CODE (b) == NEG && rtx_equal_p (XEXP (b, 0), a))
1762 c = a; a = b; b = c;
1768 cond = noce_get_alt_condition (if_info, b, &earliest);
1772 /* Verify the condition is of the form we expect. */
1773 if (rtx_equal_p (XEXP (cond, 0), b))
1775 else if (rtx_equal_p (XEXP (cond, 1), b))
1783 /* Verify that C is zero. Search one step backward for a
1784 REG_EQUAL note or a simple source if necessary. */
1787 rtx set, insn = prev_nonnote_insn (earliest);
1789 && BLOCK_NUM (insn) == BLOCK_NUM (earliest)
1790 && (set = single_set (insn))
1791 && rtx_equal_p (SET_DEST (set), c))
1793 rtx note = find_reg_equal_equiv_note (insn);
1803 && GET_CODE (XEXP (c, 0)) == SYMBOL_REF
1804 && CONSTANT_POOL_ADDRESS_P (XEXP (c, 0)))
1805 c = get_pool_constant (XEXP (c, 0));
1807 /* Work around funny ideas get_condition has wrt canonicalization.
1808 Note that these rtx constants are known to be CONST_INT, and
1809 therefore imply integer comparisons. */
1810 if (c == constm1_rtx && GET_CODE (cond) == GT)
1812 else if (c == const1_rtx && GET_CODE (cond) == LT)
1814 else if (c != CONST0_RTX (GET_MODE (b)))
1817 /* Determine what sort of operation this is. */
1818 switch (GET_CODE (cond))
1837 target = expand_abs_nojump (GET_MODE (if_info->x), b, if_info->x, 1);
1839 /* ??? It's a quandary whether cmove would be better here, especially
1840 for integers. Perhaps combine will clean things up. */
1841 if (target && negate)
1842 target = expand_simple_unop (GET_MODE (target), NEG, target, if_info->x, 0);
1850 if (target != if_info->x)
1851 noce_emit_move_insn (if_info->x, target);
1853 seq = end_ifcvt_sequence (if_info);
1857 emit_insn_before_setloc (seq, if_info->jump, INSN_LOCATOR (if_info->insn_a));
1858 if_info->cond = cond;
1859 if_info->cond_earliest = earliest;
1864 /* Convert "if (m < 0) x = b; else x = 0;" to "x = (m >> C) & b;". */
1867 noce_try_sign_mask (struct noce_if_info *if_info)
1869 rtx cond, t, m, c, seq;
1870 enum machine_mode mode;
1872 bool b_unconditional;
1874 cond = if_info->cond;
1875 code = GET_CODE (cond);
1880 if (if_info->a == const0_rtx)
1882 if ((code == LT && c == const0_rtx)
1883 || (code == LE && c == constm1_rtx))
1886 else if (if_info->b == const0_rtx)
1888 if ((code == GE && c == const0_rtx)
1889 || (code == GT && c == constm1_rtx))
1893 if (! t || side_effects_p (t))
1896 /* We currently don't handle different modes. */
1897 mode = GET_MODE (t);
1898 if (GET_MODE (m) != mode)
1901 /* This is only profitable if T is cheap, or T is unconditionally
1902 executed/evaluated in the original insn sequence. The latter
1903 happens if INSN_B was taken from TEST_BB, or if there was no
1904 INSN_B which can happen for e.g. conditional stores to memory. */
1905 b_unconditional = (if_info->insn_b == NULL_RTX
1906 || BLOCK_FOR_INSN (if_info->insn_b) == if_info->test_bb);
1907 if (rtx_cost (t, SET, optimize_bb_for_speed_p (BLOCK_FOR_INSN (if_info->insn_b)))
1908 >= COSTS_N_INSNS (2)
1909 && (!b_unconditional
1910 || t != if_info->b))
1914 /* Use emit_store_flag to generate "m < 0 ? -1 : 0" instead of expanding
1915 "(signed) m >> 31" directly. This benefits targets with specialized
1916 insns to obtain the signmask, but still uses ashr_optab otherwise. */
1917 m = emit_store_flag (gen_reg_rtx (mode), LT, m, const0_rtx, mode, 0, -1);
1918 t = m ? expand_binop (mode, and_optab, m, t, NULL_RTX, 0, OPTAB_DIRECT)
1927 noce_emit_move_insn (if_info->x, t);
1929 seq = end_ifcvt_sequence (if_info);
1933 emit_insn_before_setloc (seq, if_info->jump, INSN_LOCATOR (if_info->insn_a));
1938 /* Optimize away "if (x & C) x |= C" and similar bit manipulation
1942 noce_try_bitop (struct noce_if_info *if_info)
1944 rtx cond, x, a, result, seq;
1945 enum machine_mode mode;
1950 cond = if_info->cond;
1951 code = GET_CODE (cond);
1953 /* Check for no else condition. */
1954 if (! rtx_equal_p (x, if_info->b))
1957 /* Check for a suitable condition. */
1958 if (code != NE && code != EQ)
1960 if (XEXP (cond, 1) != const0_rtx)
1962 cond = XEXP (cond, 0);
1964 /* ??? We could also handle AND here. */
1965 if (GET_CODE (cond) == ZERO_EXTRACT)
1967 if (XEXP (cond, 1) != const1_rtx
1968 || GET_CODE (XEXP (cond, 2)) != CONST_INT
1969 || ! rtx_equal_p (x, XEXP (cond, 0)))
1971 bitnum = INTVAL (XEXP (cond, 2));
1972 mode = GET_MODE (x);
1973 if (BITS_BIG_ENDIAN)
1974 bitnum = GET_MODE_BITSIZE (mode) - 1 - bitnum;
1975 if (bitnum < 0 || bitnum >= HOST_BITS_PER_WIDE_INT)
1982 if (GET_CODE (a) == IOR || GET_CODE (a) == XOR)
1984 /* Check for "if (X & C) x = x op C". */
1985 if (! rtx_equal_p (x, XEXP (a, 0))
1986 || GET_CODE (XEXP (a, 1)) != CONST_INT
1987 || (INTVAL (XEXP (a, 1)) & GET_MODE_MASK (mode))
1988 != (unsigned HOST_WIDE_INT) 1 << bitnum)
1991 /* if ((x & C) == 0) x |= C; is transformed to x |= C. */
1992 /* if ((x & C) != 0) x |= C; is transformed to nothing. */
1993 if (GET_CODE (a) == IOR)
1994 result = (code == NE) ? a : NULL_RTX;
1995 else if (code == NE)
1997 /* if ((x & C) == 0) x ^= C; is transformed to x |= C. */
1998 result = gen_int_mode ((HOST_WIDE_INT) 1 << bitnum, mode);
1999 result = simplify_gen_binary (IOR, mode, x, result);
2003 /* if ((x & C) != 0) x ^= C; is transformed to x &= ~C. */
2004 result = gen_int_mode (~((HOST_WIDE_INT) 1 << bitnum), mode);
2005 result = simplify_gen_binary (AND, mode, x, result);
2008 else if (GET_CODE (a) == AND)
2010 /* Check for "if (X & C) x &= ~C". */
2011 if (! rtx_equal_p (x, XEXP (a, 0))
2012 || GET_CODE (XEXP (a, 1)) != CONST_INT
2013 || (INTVAL (XEXP (a, 1)) & GET_MODE_MASK (mode))
2014 != (~((HOST_WIDE_INT) 1 << bitnum) & GET_MODE_MASK (mode)))
2017 /* if ((x & C) == 0) x &= ~C; is transformed to nothing. */
2018 /* if ((x & C) != 0) x &= ~C; is transformed to x &= ~C. */
2019 result = (code == EQ) ? a : NULL_RTX;
2027 noce_emit_move_insn (x, result);
2028 seq = end_ifcvt_sequence (if_info);
2032 emit_insn_before_setloc (seq, if_info->jump,
2033 INSN_LOCATOR (if_info->insn_a));
2039 /* Similar to get_condition, only the resulting condition must be
2040 valid at JUMP, instead of at EARLIEST.
2042 If THEN_ELSE_REVERSED is true, the fallthrough does not go to the
2043 THEN block of the caller, and we have to reverse the condition. */
2046 noce_get_condition (rtx jump, rtx *earliest, bool then_else_reversed)
2051 if (! any_condjump_p (jump))
2054 set = pc_set (jump);
2056 /* If this branches to JUMP_LABEL when the condition is false,
2057 reverse the condition. */
2058 reverse = (GET_CODE (XEXP (SET_SRC (set), 2)) == LABEL_REF
2059 && XEXP (XEXP (SET_SRC (set), 2), 0) == JUMP_LABEL (jump));
2061 /* We may have to reverse because the caller's if block is not canonical,
2062 i.e. the THEN block isn't the fallthrough block for the TEST block
2063 (see find_if_header). */
2064 if (then_else_reversed)
2067 /* If the condition variable is a register and is MODE_INT, accept it. */
2069 cond = XEXP (SET_SRC (set), 0);
2070 tmp = XEXP (cond, 0);
2071 if (REG_P (tmp) && GET_MODE_CLASS (GET_MODE (tmp)) == MODE_INT)
2076 cond = gen_rtx_fmt_ee (reverse_condition (GET_CODE (cond)),
2077 GET_MODE (cond), tmp, XEXP (cond, 1));
2081 /* Otherwise, fall back on canonicalize_condition to do the dirty
2082 work of manipulating MODE_CC values and COMPARE rtx codes. */
2083 return canonicalize_condition (jump, cond, reverse, earliest,
2084 NULL_RTX, false, true);
2087 /* Return true if OP is ok for if-then-else processing. */
2090 noce_operand_ok (const_rtx op)
2092 /* We special-case memories, so handle any of them with
2093 no address side effects. */
2095 return ! side_effects_p (XEXP (op, 0));
2097 if (side_effects_p (op))
2100 return ! may_trap_p (op);
2103 /* Return true if a write into MEM may trap or fault. */
2106 noce_mem_write_may_trap_or_fault_p (const_rtx mem)
2110 if (MEM_READONLY_P (mem))
2113 if (may_trap_or_fault_p (mem))
2116 addr = XEXP (mem, 0);
2118 /* Call target hook to avoid the effects of -fpic etc.... */
2119 addr = targetm.delegitimize_address (addr);
2122 switch (GET_CODE (addr))
2130 addr = XEXP (addr, 0);
2134 addr = XEXP (addr, 1);
2137 if (GET_CODE (XEXP (addr, 1)) == CONST_INT)
2138 addr = XEXP (addr, 0);
2145 if (SYMBOL_REF_DECL (addr)
2146 && decl_readonly_section (SYMBOL_REF_DECL (addr), 0))
2156 /* Return whether we can use store speculation for MEM. TOP_BB is the
2157 basic block above the conditional block where we are considering
2158 doing the speculative store. We look for whether MEM is set
2159 unconditionally later in the function. */
2162 noce_can_store_speculate_p (basic_block top_bb, const_rtx mem)
2164 basic_block dominator;
2166 for (dominator = get_immediate_dominator (CDI_POST_DOMINATORS, top_bb);
2168 dominator = get_immediate_dominator (CDI_POST_DOMINATORS, dominator))
2172 FOR_BB_INSNS (dominator, insn)
2174 /* If we see something that might be a memory barrier, we
2175 have to stop looking. Even if the MEM is set later in
2176 the function, we still don't want to set it
2177 unconditionally before the barrier. */
2179 && (volatile_insn_p (PATTERN (insn))
2180 || (CALL_P (insn) && (!RTL_CONST_CALL_P (insn)))))
2183 if (memory_modified_in_insn_p (mem, insn))
2185 if (modified_in_p (XEXP (mem, 0), insn))
2194 /* Given a simple IF-THEN-JOIN or IF-THEN-ELSE-JOIN block, attempt to convert
2195 it without using conditional execution. Return TRUE if we were successful
2196 at converting the block. */
2199 noce_process_if_block (struct noce_if_info *if_info)
2201 basic_block test_bb = if_info->test_bb; /* test block */
2202 basic_block then_bb = if_info->then_bb; /* THEN */
2203 basic_block else_bb = if_info->else_bb; /* ELSE or NULL */
2204 basic_block join_bb = if_info->join_bb; /* JOIN */
2205 rtx jump = if_info->jump;
2206 rtx cond = if_info->cond;
2209 rtx orig_x, x, a, b;
2211 /* We're looking for patterns of the form
2213 (1) if (...) x = a; else x = b;
2214 (2) x = b; if (...) x = a;
2215 (3) if (...) x = a; // as if with an initial x = x.
2217 The later patterns require jumps to be more expensive.
2219 ??? For future expansion, look for multiple X in such patterns. */
2221 /* Look for one of the potential sets. */
2222 insn_a = first_active_insn (then_bb);
2224 || insn_a != last_active_insn (then_bb, FALSE)
2225 || (set_a = single_set (insn_a)) == NULL_RTX)
2228 x = SET_DEST (set_a);
2229 a = SET_SRC (set_a);
2231 /* Look for the other potential set. Make sure we've got equivalent
2233 /* ??? This is overconservative. Storing to two different mems is
2234 as easy as conditionally computing the address. Storing to a
2235 single mem merely requires a scratch memory to use as one of the
2236 destination addresses; often the memory immediately below the
2237 stack pointer is available for this. */
2241 insn_b = first_active_insn (else_bb);
2243 || insn_b != last_active_insn (else_bb, FALSE)
2244 || (set_b = single_set (insn_b)) == NULL_RTX
2245 || ! rtx_equal_p (x, SET_DEST (set_b)))
2250 insn_b = prev_nonnote_insn (if_info->cond_earliest);
2251 /* We're going to be moving the evaluation of B down from above
2252 COND_EARLIEST to JUMP. Make sure the relevant data is still
2255 || BLOCK_NUM (insn_b) != BLOCK_NUM (if_info->cond_earliest)
2256 || !NONJUMP_INSN_P (insn_b)
2257 || (set_b = single_set (insn_b)) == NULL_RTX
2258 || ! rtx_equal_p (x, SET_DEST (set_b))
2259 || ! noce_operand_ok (SET_SRC (set_b))
2260 || reg_overlap_mentioned_p (x, SET_SRC (set_b))
2261 || modified_between_p (SET_SRC (set_b),
2262 PREV_INSN (if_info->cond_earliest), jump)
2263 /* Likewise with X. In particular this can happen when
2264 noce_get_condition looks farther back in the instruction
2265 stream than one might expect. */
2266 || reg_overlap_mentioned_p (x, cond)
2267 || reg_overlap_mentioned_p (x, a)
2268 || modified_between_p (x, PREV_INSN (if_info->cond_earliest), jump))
2269 insn_b = set_b = NULL_RTX;
2272 /* If x has side effects then only the if-then-else form is safe to
2273 convert. But even in that case we would need to restore any notes
2274 (such as REG_INC) at then end. That can be tricky if
2275 noce_emit_move_insn expands to more than one insn, so disable the
2276 optimization entirely for now if there are side effects. */
2277 if (side_effects_p (x))
2280 b = (set_b ? SET_SRC (set_b) : x);
2282 /* Only operate on register destinations, and even then avoid extending
2283 the lifetime of hard registers on small register class machines. */
2286 || (SMALL_REGISTER_CLASSES
2287 && REGNO (x) < FIRST_PSEUDO_REGISTER))
2289 if (GET_MODE (x) == BLKmode)
2292 if (GET_CODE (x) == ZERO_EXTRACT
2293 && (GET_CODE (XEXP (x, 1)) != CONST_INT
2294 || GET_CODE (XEXP (x, 2)) != CONST_INT))
2297 x = gen_reg_rtx (GET_MODE (GET_CODE (x) == STRICT_LOW_PART
2298 ? XEXP (x, 0) : x));
2301 /* Don't operate on sources that may trap or are volatile. */
2302 if (! noce_operand_ok (a) || ! noce_operand_ok (b))
2306 /* Set up the info block for our subroutines. */
2307 if_info->insn_a = insn_a;
2308 if_info->insn_b = insn_b;
2313 /* Try optimizations in some approximation of a useful order. */
2314 /* ??? Should first look to see if X is live incoming at all. If it
2315 isn't, we don't need anything but an unconditional set. */
2317 /* Look and see if A and B are really the same. Avoid creating silly
2318 cmove constructs that no one will fix up later. */
2319 if (rtx_equal_p (a, b))
2321 /* If we have an INSN_B, we don't have to create any new rtl. Just
2322 move the instruction that we already have. If we don't have an
2323 INSN_B, that means that A == X, and we've got a noop move. In
2324 that case don't do anything and let the code below delete INSN_A. */
2325 if (insn_b && else_bb)
2329 if (else_bb && insn_b == BB_END (else_bb))
2330 BB_END (else_bb) = PREV_INSN (insn_b);
2331 reorder_insns (insn_b, insn_b, PREV_INSN (jump));
2333 /* If there was a REG_EQUAL note, delete it since it may have been
2334 true due to this insn being after a jump. */
2335 if ((note = find_reg_note (insn_b, REG_EQUAL, NULL_RTX)) != 0)
2336 remove_note (insn_b, note);
2340 /* If we have "x = b; if (...) x = a;", and x has side-effects, then
2341 x must be executed twice. */
2342 else if (insn_b && side_effects_p (orig_x))
2349 if (!set_b && MEM_P (orig_x))
2351 /* Disallow the "if (...) x = a;" form (implicit "else x = x;")
2352 for optimizations if writing to x may trap or fault,
2353 i.e. it's a memory other than a static var or a stack slot,
2354 is misaligned on strict aligned machines or is read-only. If
2355 x is a read-only memory, then the program is valid only if we
2356 avoid the store into it. If there are stores on both the
2357 THEN and ELSE arms, then we can go ahead with the conversion;
2358 either the program is broken, or the condition is always
2359 false such that the other memory is selected. */
2360 if (noce_mem_write_may_trap_or_fault_p (orig_x))
2363 /* Avoid store speculation: given "if (...) x = a" where x is a
2364 MEM, we only want to do the store if x is always set
2365 somewhere in the function. This avoids cases like
2366 if (pthread_mutex_trylock(mutex))
2368 where we only want global_variable to be changed if the mutex
2369 is held. FIXME: This should ideally be expressed directly in
2371 if (!noce_can_store_speculate_p (test_bb, orig_x))
2375 if (noce_try_move (if_info))
2377 if (noce_try_store_flag (if_info))
2379 if (noce_try_bitop (if_info))
2381 if (noce_try_minmax (if_info))
2383 if (noce_try_abs (if_info))
2385 if (HAVE_conditional_move
2386 && noce_try_cmove (if_info))
2388 if (! HAVE_conditional_execution)
2390 if (noce_try_store_flag_constants (if_info))
2392 if (noce_try_addcc (if_info))
2394 if (noce_try_store_flag_mask (if_info))
2396 if (HAVE_conditional_move
2397 && noce_try_cmove_arith (if_info))
2399 if (noce_try_sign_mask (if_info))
2403 if (!else_bb && set_b)
2405 insn_b = set_b = NULL_RTX;
2414 /* If we used a temporary, fix it up now. */
2420 noce_emit_move_insn (orig_x, x);
2422 set_used_flags (orig_x);
2423 unshare_all_rtl_in_chain (seq);
2426 emit_insn_before_setloc (seq, BB_END (test_bb), INSN_LOCATOR (insn_a));
2429 /* The original THEN and ELSE blocks may now be removed. The test block
2430 must now jump to the join block. If the test block and the join block
2431 can be merged, do so. */
2434 delete_basic_block (else_bb);
2438 remove_edge (find_edge (test_bb, join_bb));
2440 remove_edge (find_edge (then_bb, join_bb));
2441 redirect_edge_and_branch_force (single_succ_edge (test_bb), join_bb);
2442 delete_basic_block (then_bb);
2445 if (can_merge_blocks_p (test_bb, join_bb))
2447 merge_blocks (test_bb, join_bb);
2451 num_updated_if_blocks++;
2455 /* Check whether a block is suitable for conditional move conversion.
2456 Every insn must be a simple set of a register to a constant or a
2457 register. For each assignment, store the value in the array VALS,
2458 indexed by register number, then store the register number in
2459 REGS. COND is the condition we will test. */
2462 check_cond_move_block (basic_block bb, rtx *vals, VEC (int, heap) **regs, rtx cond)
2466 /* We can only handle simple jumps at the end of the basic block.
2467 It is almost impossible to update the CFG otherwise. */
2469 if (JUMP_P (insn) && !onlyjump_p (insn))
2472 FOR_BB_INSNS (bb, insn)
2476 if (!INSN_P (insn) || JUMP_P (insn))
2478 set = single_set (insn);
2482 dest = SET_DEST (set);
2483 src = SET_SRC (set);
2485 || (SMALL_REGISTER_CLASSES && HARD_REGISTER_P (dest)))
2488 if (!CONSTANT_P (src) && !register_operand (src, VOIDmode))
2491 if (side_effects_p (src) || side_effects_p (dest))
2494 if (may_trap_p (src) || may_trap_p (dest))
2497 /* Don't try to handle this if the source register was
2498 modified earlier in the block. */
2500 && vals[REGNO (src)] != NULL)
2501 || (GET_CODE (src) == SUBREG && REG_P (SUBREG_REG (src))
2502 && vals[REGNO (SUBREG_REG (src))] != NULL))
2505 /* Don't try to handle this if the destination register was
2506 modified earlier in the block. */
2507 if (vals[REGNO (dest)] != NULL)
2510 /* Don't try to handle this if the condition uses the
2511 destination register. */
2512 if (reg_overlap_mentioned_p (dest, cond))
2515 /* Don't try to handle this if the source register is modified
2516 later in the block. */
2517 if (!CONSTANT_P (src)
2518 && modified_between_p (src, insn, NEXT_INSN (BB_END (bb))))
2521 vals[REGNO (dest)] = src;
2523 VEC_safe_push (int, heap, *regs, REGNO (dest));
2529 /* Given a basic block BB suitable for conditional move conversion,
2530 a condition COND, and arrays THEN_VALS and ELSE_VALS containing the
2531 register values depending on COND, emit the insns in the block as
2532 conditional moves. If ELSE_BLOCK is true, THEN_BB was already
2533 processed. The caller has started a sequence for the conversion.
2534 Return true if successful, false if something goes wrong. */
2537 cond_move_convert_if_block (struct noce_if_info *if_infop,
2538 basic_block bb, rtx cond,
2539 rtx *then_vals, rtx *else_vals,
2543 rtx insn, cond_arg0, cond_arg1;
2545 code = GET_CODE (cond);
2546 cond_arg0 = XEXP (cond, 0);
2547 cond_arg1 = XEXP (cond, 1);
2549 FOR_BB_INSNS (bb, insn)
2551 rtx set, target, dest, t, e;
2554 if (!INSN_P (insn) || JUMP_P (insn))
2556 set = single_set (insn);
2557 gcc_assert (set && REG_P (SET_DEST (set)));
2559 dest = SET_DEST (set);
2560 regno = REGNO (dest);
2562 t = then_vals[regno];
2563 e = else_vals[regno];
2567 /* If this register was set in the then block, we already
2568 handled this case there. */
2581 target = noce_emit_cmove (if_infop, dest, code, cond_arg0, cond_arg1,
2587 noce_emit_move_insn (dest, target);
2593 /* Given a simple IF-THEN-JOIN or IF-THEN-ELSE-JOIN block, attempt to convert
2594 it using only conditional moves. Return TRUE if we were successful at
2595 converting the block. */
2598 cond_move_process_if_block (struct noce_if_info *if_info)
2600 basic_block test_bb = if_info->test_bb;
2601 basic_block then_bb = if_info->then_bb;
2602 basic_block else_bb = if_info->else_bb;
2603 basic_block join_bb = if_info->join_bb;
2604 rtx jump = if_info->jump;
2605 rtx cond = if_info->cond;
2607 int max_reg, size, c, reg;
2610 VEC (int, heap) *then_regs = NULL;
2611 VEC (int, heap) *else_regs = NULL;
2614 /* Build a mapping for each block to the value used for each
2616 max_reg = max_reg_num ();
2617 size = (max_reg + 1) * sizeof (rtx);
2618 then_vals = (rtx *) alloca (size);
2619 else_vals = (rtx *) alloca (size);
2620 memset (then_vals, 0, size);
2621 memset (else_vals, 0, size);
2623 /* Make sure the blocks are suitable. */
2624 if (!check_cond_move_block (then_bb, then_vals, &then_regs, cond)
2625 || (else_bb && !check_cond_move_block (else_bb, else_vals, &else_regs, cond)))
2627 VEC_free (int, heap, then_regs);
2628 VEC_free (int, heap, else_regs);
2632 /* Make sure the blocks can be used together. If the same register
2633 is set in both blocks, and is not set to a constant in both
2634 cases, then both blocks must set it to the same register. We
2635 have already verified that if it is set to a register, that the
2636 source register does not change after the assignment. Also count
2637 the number of registers set in only one of the blocks. */
2639 for (i = 0; VEC_iterate (int, then_regs, i, reg); i++)
2641 if (!then_vals[reg] && !else_vals[reg])
2644 if (!else_vals[reg])
2648 if (!CONSTANT_P (then_vals[reg])
2649 && !CONSTANT_P (else_vals[reg])
2650 && !rtx_equal_p (then_vals[reg], else_vals[reg]))
2652 VEC_free (int, heap, then_regs);
2653 VEC_free (int, heap, else_regs);
2659 /* Finish off c for MAX_CONDITIONAL_EXECUTE. */
2660 for (i = 0; VEC_iterate (int, else_regs, i, reg); ++i)
2661 if (!then_vals[reg])
2664 /* Make sure it is reasonable to convert this block. What matters
2665 is the number of assignments currently made in only one of the
2666 branches, since if we convert we are going to always execute
2668 if (c > MAX_CONDITIONAL_EXECUTE)
2670 VEC_free (int, heap, then_regs);
2671 VEC_free (int, heap, else_regs);
2675 /* Try to emit the conditional moves. First do the then block,
2676 then do anything left in the else blocks. */
2678 if (!cond_move_convert_if_block (if_info, then_bb, cond,
2679 then_vals, else_vals, false)
2681 && !cond_move_convert_if_block (if_info, else_bb, cond,
2682 then_vals, else_vals, true)))
2685 VEC_free (int, heap, then_regs);
2686 VEC_free (int, heap, else_regs);
2689 seq = end_ifcvt_sequence (if_info);
2692 VEC_free (int, heap, then_regs);
2693 VEC_free (int, heap, else_regs);
2697 loc_insn = first_active_insn (then_bb);
2700 loc_insn = first_active_insn (else_bb);
2701 gcc_assert (loc_insn);
2703 emit_insn_before_setloc (seq, jump, INSN_LOCATOR (loc_insn));
2707 delete_basic_block (else_bb);
2711 remove_edge (find_edge (test_bb, join_bb));
2713 remove_edge (find_edge (then_bb, join_bb));
2714 redirect_edge_and_branch_force (single_succ_edge (test_bb), join_bb);
2715 delete_basic_block (then_bb);
2718 if (can_merge_blocks_p (test_bb, join_bb))
2720 merge_blocks (test_bb, join_bb);
2724 num_updated_if_blocks++;
2726 VEC_free (int, heap, then_regs);
2727 VEC_free (int, heap, else_regs);
2732 /* Determine if a given basic block heads a simple IF-THEN-JOIN or an
2733 IF-THEN-ELSE-JOIN block.
2735 If so, we'll try to convert the insns to not require the branch,
2736 using only transformations that do not require conditional execution.
2738 Return TRUE if we were successful at converting the block. */
2741 noce_find_if_block (basic_block test_bb,
2742 edge then_edge, edge else_edge,
2745 basic_block then_bb, else_bb, join_bb;
2746 bool then_else_reversed = false;
2749 struct noce_if_info if_info;
2751 /* We only ever should get here before reload. */
2752 gcc_assert (!reload_completed);
2754 /* Recognize an IF-THEN-ELSE-JOIN block. */
2755 if (single_pred_p (then_edge->dest)
2756 && single_succ_p (then_edge->dest)
2757 && single_pred_p (else_edge->dest)
2758 && single_succ_p (else_edge->dest)
2759 && single_succ (then_edge->dest) == single_succ (else_edge->dest))
2761 then_bb = then_edge->dest;
2762 else_bb = else_edge->dest;
2763 join_bb = single_succ (then_bb);
2765 /* Recognize an IF-THEN-JOIN block. */
2766 else if (single_pred_p (then_edge->dest)
2767 && single_succ_p (then_edge->dest)
2768 && single_succ (then_edge->dest) == else_edge->dest)
2770 then_bb = then_edge->dest;
2771 else_bb = NULL_BLOCK;
2772 join_bb = else_edge->dest;
2774 /* Recognize an IF-ELSE-JOIN block. We can have those because the order
2775 of basic blocks in cfglayout mode does not matter, so the fallthrough
2776 edge can go to any basic block (and not just to bb->next_bb, like in
2778 else if (single_pred_p (else_edge->dest)
2779 && single_succ_p (else_edge->dest)
2780 && single_succ (else_edge->dest) == then_edge->dest)
2782 /* The noce transformations do not apply to IF-ELSE-JOIN blocks.
2783 To make this work, we have to invert the THEN and ELSE blocks
2784 and reverse the jump condition. */
2785 then_bb = else_edge->dest;
2786 else_bb = NULL_BLOCK;
2787 join_bb = single_succ (then_bb);
2788 then_else_reversed = true;
2791 /* Not a form we can handle. */
2794 /* The edges of the THEN and ELSE blocks cannot have complex edges. */
2795 if (single_succ_edge (then_bb)->flags & EDGE_COMPLEX)
2798 && single_succ_edge (else_bb)->flags & EDGE_COMPLEX)
2801 num_possible_if_blocks++;
2806 "\nIF-THEN%s-JOIN block found, pass %d, test %d, then %d",
2807 (else_bb) ? "-ELSE" : "",
2808 pass, test_bb->index, then_bb->index);
2811 fprintf (dump_file, ", else %d", else_bb->index);
2813 fprintf (dump_file, ", join %d\n", join_bb->index);
2816 /* If the conditional jump is more than just a conditional
2817 jump, then we can not do if-conversion on this block. */
2818 jump = BB_END (test_bb);
2819 if (! onlyjump_p (jump))
2822 /* If this is not a standard conditional jump, we can't parse it. */
2823 cond = noce_get_condition (jump,
2825 then_else_reversed);
2829 /* We must be comparing objects whose modes imply the size. */
2830 if (GET_MODE (XEXP (cond, 0)) == BLKmode)
2833 /* Initialize an IF_INFO struct to pass around. */
2834 memset (&if_info, 0, sizeof if_info);
2835 if_info.test_bb = test_bb;
2836 if_info.then_bb = then_bb;
2837 if_info.else_bb = else_bb;
2838 if_info.join_bb = join_bb;
2839 if_info.cond = cond;
2840 if_info.cond_earliest = cond_earliest;
2841 if_info.jump = jump;
2842 if_info.then_else_reversed = then_else_reversed;
2843 if_info.branch_cost = BRANCH_COST (optimize_bb_for_speed_p (test_bb),
2844 predictable_edge_p (then_edge));
2846 /* Do the real work. */
2848 if (noce_process_if_block (&if_info))
2851 if (HAVE_conditional_move
2852 && cond_move_process_if_block (&if_info))
2859 /* Merge the blocks and mark for local life update. */
2862 merge_if_block (struct ce_if_block * ce_info)
2864 basic_block test_bb = ce_info->test_bb; /* last test block */
2865 basic_block then_bb = ce_info->then_bb; /* THEN */
2866 basic_block else_bb = ce_info->else_bb; /* ELSE or NULL */
2867 basic_block join_bb = ce_info->join_bb; /* join block */
2868 basic_block combo_bb;
2870 /* All block merging is done into the lower block numbers. */
2873 df_set_bb_dirty (test_bb);
2875 /* Merge any basic blocks to handle && and || subtests. Each of
2876 the blocks are on the fallthru path from the predecessor block. */
2877 if (ce_info->num_multiple_test_blocks > 0)
2879 basic_block bb = test_bb;
2880 basic_block last_test_bb = ce_info->last_test_bb;
2881 basic_block fallthru = block_fallthru (bb);
2886 fallthru = block_fallthru (bb);
2887 merge_blocks (combo_bb, bb);
2890 while (bb != last_test_bb);
2893 /* Merge TEST block into THEN block. Normally the THEN block won't have a
2894 label, but it might if there were || tests. That label's count should be
2895 zero, and it normally should be removed. */
2899 merge_blocks (combo_bb, then_bb);
2903 /* The ELSE block, if it existed, had a label. That label count
2904 will almost always be zero, but odd things can happen when labels
2905 get their addresses taken. */
2908 merge_blocks (combo_bb, else_bb);
2912 /* If there was no join block reported, that means it was not adjacent
2913 to the others, and so we cannot merge them. */
2917 rtx last = BB_END (combo_bb);
2919 /* The outgoing edge for the current COMBO block should already
2920 be correct. Verify this. */
2921 if (EDGE_COUNT (combo_bb->succs) == 0)
2922 gcc_assert (find_reg_note (last, REG_NORETURN, NULL)
2923 || (NONJUMP_INSN_P (last)
2924 && GET_CODE (PATTERN (last)) == TRAP_IF
2925 && (TRAP_CONDITION (PATTERN (last))
2926 == const_true_rtx)));
2929 /* There should still be something at the end of the THEN or ELSE
2930 blocks taking us to our final destination. */
2931 gcc_assert (JUMP_P (last)
2932 || (EDGE_SUCC (combo_bb, 0)->dest == EXIT_BLOCK_PTR
2934 && SIBLING_CALL_P (last))
2935 || ((EDGE_SUCC (combo_bb, 0)->flags & EDGE_EH)
2936 && can_throw_internal (last)));
2939 /* The JOIN block may have had quite a number of other predecessors too.
2940 Since we've already merged the TEST, THEN and ELSE blocks, we should
2941 have only one remaining edge from our if-then-else diamond. If there
2942 is more than one remaining edge, it must come from elsewhere. There
2943 may be zero incoming edges if the THEN block didn't actually join
2944 back up (as with a call to a non-return function). */
2945 else if (EDGE_COUNT (join_bb->preds) < 2
2946 && join_bb != EXIT_BLOCK_PTR)
2948 /* We can merge the JOIN cleanly and update the dataflow try
2949 again on this pass.*/
2950 merge_blocks (combo_bb, join_bb);
2955 /* We cannot merge the JOIN. */
2957 /* The outgoing edge for the current COMBO block should already
2958 be correct. Verify this. */
2959 gcc_assert (single_succ_p (combo_bb)
2960 && single_succ (combo_bb) == join_bb);
2962 /* Remove the jump and cruft from the end of the COMBO block. */
2963 if (join_bb != EXIT_BLOCK_PTR)
2964 tidy_fallthru_edge (single_succ_edge (combo_bb));
2967 num_updated_if_blocks++;
2970 /* Find a block ending in a simple IF condition and try to transform it
2971 in some way. When converting a multi-block condition, put the new code
2972 in the first such block and delete the rest. Return a pointer to this
2973 first block if some transformation was done. Return NULL otherwise. */
2976 find_if_header (basic_block test_bb, int pass)
2978 ce_if_block_t ce_info;
2982 /* The kind of block we're looking for has exactly two successors. */
2983 if (EDGE_COUNT (test_bb->succs) != 2)
2986 then_edge = EDGE_SUCC (test_bb, 0);
2987 else_edge = EDGE_SUCC (test_bb, 1);
2989 if (df_get_bb_dirty (then_edge->dest))
2991 if (df_get_bb_dirty (else_edge->dest))
2994 /* Neither edge should be abnormal. */
2995 if ((then_edge->flags & EDGE_COMPLEX)
2996 || (else_edge->flags & EDGE_COMPLEX))
2999 /* Nor exit the loop. */
3000 if ((then_edge->flags & EDGE_LOOP_EXIT)
3001 || (else_edge->flags & EDGE_LOOP_EXIT))
3004 /* The THEN edge is canonically the one that falls through. */
3005 if (then_edge->flags & EDGE_FALLTHRU)
3007 else if (else_edge->flags & EDGE_FALLTHRU)
3010 else_edge = then_edge;
3014 /* Otherwise this must be a multiway branch of some sort. */
3017 memset (&ce_info, '\0', sizeof (ce_info));
3018 ce_info.test_bb = test_bb;
3019 ce_info.then_bb = then_edge->dest;
3020 ce_info.else_bb = else_edge->dest;
3021 ce_info.pass = pass;
3023 #ifdef IFCVT_INIT_EXTRA_FIELDS
3024 IFCVT_INIT_EXTRA_FIELDS (&ce_info);
3027 if (! reload_completed
3028 && noce_find_if_block (test_bb, then_edge, else_edge, pass))
3031 if (HAVE_conditional_execution && reload_completed
3032 && cond_exec_find_if_block (&ce_info))
3035 if (HAVE_trap && HAVE_conditional_trap
3036 && find_cond_trap (test_bb, then_edge, else_edge))
3039 if (dom_info_state (CDI_POST_DOMINATORS) >= DOM_NO_FAST_QUERY
3040 && (! HAVE_conditional_execution || reload_completed))
3042 if (find_if_case_1 (test_bb, then_edge, else_edge))
3044 if (find_if_case_2 (test_bb, then_edge, else_edge))
3052 fprintf (dump_file, "Conversion succeeded on pass %d.\n", pass);
3053 /* Set this so we continue looking. */
3054 cond_exec_changed_p = TRUE;
3055 return ce_info.test_bb;
3058 /* Return true if a block has two edges, one of which falls through to the next
3059 block, and the other jumps to a specific block, so that we can tell if the
3060 block is part of an && test or an || test. Returns either -1 or the number
3061 of non-note, non-jump, non-USE/CLOBBER insns in the block. */
3064 block_jumps_and_fallthru_p (basic_block cur_bb, basic_block target_bb)
3067 int fallthru_p = FALSE;
3074 if (!cur_bb || !target_bb)
3077 /* If no edges, obviously it doesn't jump or fallthru. */
3078 if (EDGE_COUNT (cur_bb->succs) == 0)
3081 FOR_EACH_EDGE (cur_edge, ei, cur_bb->succs)
3083 if (cur_edge->flags & EDGE_COMPLEX)
3084 /* Anything complex isn't what we want. */
3087 else if (cur_edge->flags & EDGE_FALLTHRU)
3090 else if (cur_edge->dest == target_bb)
3097 if ((jump_p & fallthru_p) == 0)
3100 /* Don't allow calls in the block, since this is used to group && and ||
3101 together for conditional execution support. ??? we should support
3102 conditional execution support across calls for IA-64 some day, but
3103 for now it makes the code simpler. */
3104 end = BB_END (cur_bb);
3105 insn = BB_HEAD (cur_bb);
3107 while (insn != NULL_RTX)
3114 && GET_CODE (PATTERN (insn)) != USE
3115 && GET_CODE (PATTERN (insn)) != CLOBBER)
3121 insn = NEXT_INSN (insn);
3127 /* Determine if a given basic block heads a simple IF-THEN or IF-THEN-ELSE
3128 block. If so, we'll try to convert the insns to not require the branch.
3129 Return TRUE if we were successful at converting the block. */
3132 cond_exec_find_if_block (struct ce_if_block * ce_info)
3134 basic_block test_bb = ce_info->test_bb;
3135 basic_block then_bb = ce_info->then_bb;
3136 basic_block else_bb = ce_info->else_bb;
3137 basic_block join_bb = NULL_BLOCK;
3142 ce_info->last_test_bb = test_bb;
3144 /* We only ever should get here after reload,
3145 and only if we have conditional execution. */
3146 gcc_assert (HAVE_conditional_execution && reload_completed);
3148 /* Discover if any fall through predecessors of the current test basic block
3149 were && tests (which jump to the else block) or || tests (which jump to
3151 if (single_pred_p (test_bb)
3152 && single_pred_edge (test_bb)->flags == EDGE_FALLTHRU)
3154 basic_block bb = single_pred (test_bb);
3155 basic_block target_bb;
3156 int max_insns = MAX_CONDITIONAL_EXECUTE;
3159 /* Determine if the preceding block is an && or || block. */
3160 if ((n_insns = block_jumps_and_fallthru_p (bb, else_bb)) >= 0)
3162 ce_info->and_and_p = TRUE;
3163 target_bb = else_bb;
3165 else if ((n_insns = block_jumps_and_fallthru_p (bb, then_bb)) >= 0)
3167 ce_info->and_and_p = FALSE;
3168 target_bb = then_bb;
3171 target_bb = NULL_BLOCK;
3173 if (target_bb && n_insns <= max_insns)
3175 int total_insns = 0;
3178 ce_info->last_test_bb = test_bb;
3180 /* Found at least one && or || block, look for more. */
3183 ce_info->test_bb = test_bb = bb;
3184 total_insns += n_insns;
3187 if (!single_pred_p (bb))
3190 bb = single_pred (bb);
3191 n_insns = block_jumps_and_fallthru_p (bb, target_bb);
3193 while (n_insns >= 0 && (total_insns + n_insns) <= max_insns);
3195 ce_info->num_multiple_test_blocks = blocks;
3196 ce_info->num_multiple_test_insns = total_insns;
3198 if (ce_info->and_and_p)
3199 ce_info->num_and_and_blocks = blocks;
3201 ce_info->num_or_or_blocks = blocks;
3205 /* The THEN block of an IF-THEN combo must have exactly one predecessor,
3206 other than any || blocks which jump to the THEN block. */
3207 if ((EDGE_COUNT (then_bb->preds) - ce_info->num_or_or_blocks) != 1)
3210 /* The edges of the THEN and ELSE blocks cannot have complex edges. */
3211 FOR_EACH_EDGE (cur_edge, ei, then_bb->preds)
3213 if (cur_edge->flags & EDGE_COMPLEX)
3217 FOR_EACH_EDGE (cur_edge, ei, else_bb->preds)
3219 if (cur_edge->flags & EDGE_COMPLEX)
3223 /* The THEN block of an IF-THEN combo must have zero or one successors. */
3224 if (EDGE_COUNT (then_bb->succs) > 0
3225 && (!single_succ_p (then_bb)
3226 || (single_succ_edge (then_bb)->flags & EDGE_COMPLEX)
3227 || (epilogue_completed && tablejump_p (BB_END (then_bb), NULL, NULL))))
3230 /* If the THEN block has no successors, conditional execution can still
3231 make a conditional call. Don't do this unless the ELSE block has
3232 only one incoming edge -- the CFG manipulation is too ugly otherwise.
3233 Check for the last insn of the THEN block being an indirect jump, which
3234 is listed as not having any successors, but confuses the rest of the CE
3235 code processing. ??? we should fix this in the future. */
3236 if (EDGE_COUNT (then_bb->succs) == 0)
3238 if (single_pred_p (else_bb))
3240 rtx last_insn = BB_END (then_bb);
3243 && NOTE_P (last_insn)
3244 && last_insn != BB_HEAD (then_bb))
3245 last_insn = PREV_INSN (last_insn);
3248 && JUMP_P (last_insn)
3249 && ! simplejump_p (last_insn))
3253 else_bb = NULL_BLOCK;
3259 /* If the THEN block's successor is the other edge out of the TEST block,
3260 then we have an IF-THEN combo without an ELSE. */
3261 else if (single_succ (then_bb) == else_bb)
3264 else_bb = NULL_BLOCK;
3267 /* If the THEN and ELSE block meet in a subsequent block, and the ELSE
3268 has exactly one predecessor and one successor, and the outgoing edge
3269 is not complex, then we have an IF-THEN-ELSE combo. */
3270 else if (single_succ_p (else_bb)
3271 && single_succ (then_bb) == single_succ (else_bb)
3272 && single_pred_p (else_bb)
3273 && ! (single_succ_edge (else_bb)->flags & EDGE_COMPLEX)
3274 && ! (epilogue_completed && tablejump_p (BB_END (else_bb), NULL, NULL)))
3275 join_bb = single_succ (else_bb);
3277 /* Otherwise it is not an IF-THEN or IF-THEN-ELSE combination. */
3281 num_possible_if_blocks++;
3286 "\nIF-THEN%s block found, pass %d, start block %d "
3287 "[insn %d], then %d [%d]",
3288 (else_bb) ? "-ELSE" : "",
3291 BB_HEAD (test_bb) ? (int)INSN_UID (BB_HEAD (test_bb)) : -1,
3293 BB_HEAD (then_bb) ? (int)INSN_UID (BB_HEAD (then_bb)) : -1);
3296 fprintf (dump_file, ", else %d [%d]",
3298 BB_HEAD (else_bb) ? (int)INSN_UID (BB_HEAD (else_bb)) : -1);
3300 fprintf (dump_file, ", join %d [%d]",
3302 BB_HEAD (join_bb) ? (int)INSN_UID (BB_HEAD (join_bb)) : -1);
3304 if (ce_info->num_multiple_test_blocks > 0)
3305 fprintf (dump_file, ", %d %s block%s last test %d [%d]",
3306 ce_info->num_multiple_test_blocks,
3307 (ce_info->and_and_p) ? "&&" : "||",
3308 (ce_info->num_multiple_test_blocks == 1) ? "" : "s",
3309 ce_info->last_test_bb->index,
3310 ((BB_HEAD (ce_info->last_test_bb))
3311 ? (int)INSN_UID (BB_HEAD (ce_info->last_test_bb))
3314 fputc ('\n', dump_file);
3317 /* Make sure IF, THEN, and ELSE, blocks are adjacent. Actually, we get the
3318 first condition for free, since we've already asserted that there's a
3319 fallthru edge from IF to THEN. Likewise for the && and || blocks, since
3320 we checked the FALLTHRU flag, those are already adjacent to the last IF
3322 /* ??? As an enhancement, move the ELSE block. Have to deal with
3323 BLOCK notes, if by no other means than backing out the merge if they
3324 exist. Sticky enough I don't want to think about it now. */
3326 if (else_bb && (next = next->next_bb) != else_bb)
3328 if ((next = next->next_bb) != join_bb && join_bb != EXIT_BLOCK_PTR)
3336 /* Do the real work. */
3338 ce_info->else_bb = else_bb;
3339 ce_info->join_bb = join_bb;
3341 /* If we have && and || tests, try to first handle combining the && and ||
3342 tests into the conditional code, and if that fails, go back and handle
3343 it without the && and ||, which at present handles the && case if there
3344 was no ELSE block. */
3345 if (cond_exec_process_if_block (ce_info, TRUE))
3348 if (ce_info->num_multiple_test_blocks)
3352 if (cond_exec_process_if_block (ce_info, FALSE))
3359 /* Convert a branch over a trap, or a branch
3360 to a trap, into a conditional trap. */
3363 find_cond_trap (basic_block test_bb, edge then_edge, edge else_edge)
3365 basic_block then_bb = then_edge->dest;
3366 basic_block else_bb = else_edge->dest;
3367 basic_block other_bb, trap_bb;
3368 rtx trap, jump, cond, cond_earliest, seq;
3371 /* Locate the block with the trap instruction. */
3372 /* ??? While we look for no successors, we really ought to allow
3373 EH successors. Need to fix merge_if_block for that to work. */
3374 if ((trap = block_has_only_trap (then_bb)) != NULL)
3375 trap_bb = then_bb, other_bb = else_bb;
3376 else if ((trap = block_has_only_trap (else_bb)) != NULL)
3377 trap_bb = else_bb, other_bb = then_bb;
3383 fprintf (dump_file, "\nTRAP-IF block found, start %d, trap %d\n",
3384 test_bb->index, trap_bb->index);
3387 /* If this is not a standard conditional jump, we can't parse it. */
3388 jump = BB_END (test_bb);
3389 cond = noce_get_condition (jump, &cond_earliest, false);
3393 /* If the conditional jump is more than just a conditional jump, then
3394 we can not do if-conversion on this block. */
3395 if (! onlyjump_p (jump))
3398 /* We must be comparing objects whose modes imply the size. */
3399 if (GET_MODE (XEXP (cond, 0)) == BLKmode)
3402 /* Reverse the comparison code, if necessary. */
3403 code = GET_CODE (cond);
3404 if (then_bb == trap_bb)
3406 code = reversed_comparison_code (cond, jump);
3407 if (code == UNKNOWN)
3411 /* Attempt to generate the conditional trap. */
3412 seq = gen_cond_trap (code, copy_rtx (XEXP (cond, 0)),
3413 copy_rtx (XEXP (cond, 1)),
3414 TRAP_CODE (PATTERN (trap)));
3418 /* Emit the new insns before cond_earliest. */
3419 emit_insn_before_setloc (seq, cond_earliest, INSN_LOCATOR (trap));
3421 /* Delete the trap block if possible. */
3422 remove_edge (trap_bb == then_bb ? then_edge : else_edge);
3423 df_set_bb_dirty (test_bb);
3424 df_set_bb_dirty (then_bb);
3425 df_set_bb_dirty (else_bb);
3427 if (EDGE_COUNT (trap_bb->preds) == 0)
3429 delete_basic_block (trap_bb);
3433 /* Wire together the blocks again. */
3434 if (current_ir_type () == IR_RTL_CFGLAYOUT)
3435 single_succ_edge (test_bb)->flags |= EDGE_FALLTHRU;
3440 lab = JUMP_LABEL (jump);
3441 newjump = emit_jump_insn_after (gen_jump (lab), jump);
3442 LABEL_NUSES (lab) += 1;
3443 JUMP_LABEL (newjump) = lab;
3444 emit_barrier_after (newjump);
3448 if (can_merge_blocks_p (test_bb, other_bb))
3450 merge_blocks (test_bb, other_bb);
3454 num_updated_if_blocks++;
3458 /* Subroutine of find_cond_trap: if BB contains only a trap insn,
3462 block_has_only_trap (basic_block bb)
3466 /* We're not the exit block. */
3467 if (bb == EXIT_BLOCK_PTR)
3470 /* The block must have no successors. */
3471 if (EDGE_COUNT (bb->succs) > 0)
3474 /* The only instruction in the THEN block must be the trap. */
3475 trap = first_active_insn (bb);
3476 if (! (trap == BB_END (bb)
3477 && GET_CODE (PATTERN (trap)) == TRAP_IF
3478 && TRAP_CONDITION (PATTERN (trap)) == const_true_rtx))
3484 /* Look for IF-THEN-ELSE cases in which one of THEN or ELSE is
3485 transformable, but not necessarily the other. There need be no
3488 Return TRUE if we were successful at converting the block.
3490 Cases we'd like to look at:
3493 if (test) goto over; // x not live
3501 if (! test) goto label;
3504 if (test) goto E; // x not live
3518 (3) // This one's really only interesting for targets that can do
3519 // multiway branching, e.g. IA-64 BBB bundles. For other targets
3520 // it results in multiple branches on a cache line, which often
3521 // does not sit well with predictors.
3523 if (test1) goto E; // predicted not taken
3539 (A) Don't do (2) if the branch is predicted against the block we're
3540 eliminating. Do it anyway if we can eliminate a branch; this requires
3541 that the sole successor of the eliminated block postdominate the other
3544 (B) With CE, on (3) we can steal from both sides of the if, creating
3553 Again, this is most useful if J postdominates.
3555 (C) CE substitutes for helpful life information.
3557 (D) These heuristics need a lot of work. */
3559 /* Tests for case 1 above. */
3562 find_if_case_1 (basic_block test_bb, edge then_edge, edge else_edge)
3564 basic_block then_bb = then_edge->dest;
3565 basic_block else_bb = else_edge->dest;
3569 /* If we are partitioning hot/cold basic blocks, we don't want to
3570 mess up unconditional or indirect jumps that cross between hot
3573 Basic block partitioning may result in some jumps that appear to
3574 be optimizable (or blocks that appear to be mergeable), but which really
3575 must be left untouched (they are required to make it safely across
3576 partition boundaries). See the comments at the top of
3577 bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */
3579 if ((BB_END (then_bb)
3580 && find_reg_note (BB_END (then_bb), REG_CROSSING_JUMP, NULL_RTX))
3581 || (BB_END (test_bb)
3582 && find_reg_note (BB_END (test_bb), REG_CROSSING_JUMP, NULL_RTX))
3583 || (BB_END (else_bb)
3584 && find_reg_note (BB_END (else_bb), REG_CROSSING_JUMP,
3588 /* THEN has one successor. */
3589 if (!single_succ_p (then_bb))
3592 /* THEN does not fall through, but is not strange either. */
3593 if (single_succ_edge (then_bb)->flags & (EDGE_COMPLEX | EDGE_FALLTHRU))
3596 /* THEN has one predecessor. */
3597 if (!single_pred_p (then_bb))
3600 /* THEN must do something. */
3601 if (forwarder_block_p (then_bb))
3604 num_possible_if_blocks++;
3607 "\nIF-CASE-1 found, start %d, then %d\n",
3608 test_bb->index, then_bb->index);
3610 /* THEN is small. */
3611 if (! cheap_bb_rtx_cost_p (then_bb,
3612 COSTS_N_INSNS (BRANCH_COST (optimize_bb_for_speed_p (then_edge->src),
3613 predictable_edge_p (then_edge)))))
3616 /* Registers set are dead, or are predicable. */
3617 if (! dead_or_predicable (test_bb, then_bb, else_bb,
3618 single_succ (then_bb), 1))
3621 /* Conversion went ok, including moving the insns and fixing up the
3622 jump. Adjust the CFG to match. */
3624 /* We can avoid creating a new basic block if then_bb is immediately
3625 followed by else_bb, i.e. deleting then_bb allows test_bb to fall
3628 if (then_bb->next_bb == else_bb
3629 && then_bb->prev_bb == test_bb
3630 && else_bb != EXIT_BLOCK_PTR)
3632 redirect_edge_succ (FALLTHRU_EDGE (test_bb), else_bb);
3636 new_bb = redirect_edge_and_branch_force (FALLTHRU_EDGE (test_bb),
3639 df_set_bb_dirty (test_bb);
3640 df_set_bb_dirty (else_bb);
3642 then_bb_index = then_bb->index;
3643 delete_basic_block (then_bb);
3645 /* Make rest of code believe that the newly created block is the THEN_BB
3646 block we removed. */
3649 df_bb_replace (then_bb_index, new_bb);
3650 /* Since the fallthru edge was redirected from test_bb to new_bb,
3651 we need to ensure that new_bb is in the same partition as
3652 test bb (you can not fall through across section boundaries). */
3653 BB_COPY_PARTITION (new_bb, test_bb);
3657 num_updated_if_blocks++;
3662 /* Test for case 2 above. */
3665 find_if_case_2 (basic_block test_bb, edge then_edge, edge else_edge)
3667 basic_block then_bb = then_edge->dest;
3668 basic_block else_bb = else_edge->dest;
3672 /* If we are partitioning hot/cold basic blocks, we don't want to
3673 mess up unconditional or indirect jumps that cross between hot
3676 Basic block partitioning may result in some jumps that appear to
3677 be optimizable (or blocks that appear to be mergeable), but which really
3678 must be left untouched (they are required to make it safely across
3679 partition boundaries). See the comments at the top of
3680 bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */
3682 if ((BB_END (then_bb)
3683 && find_reg_note (BB_END (then_bb), REG_CROSSING_JUMP, NULL_RTX))
3684 || (BB_END (test_bb)
3685 && find_reg_note (BB_END (test_bb), REG_CROSSING_JUMP, NULL_RTX))
3686 || (BB_END (else_bb)
3687 && find_reg_note (BB_END (else_bb), REG_CROSSING_JUMP,
3691 /* ELSE has one successor. */
3692 if (!single_succ_p (else_bb))
3695 else_succ = single_succ_edge (else_bb);
3697 /* ELSE outgoing edge is not complex. */
3698 if (else_succ->flags & EDGE_COMPLEX)
3701 /* ELSE has one predecessor. */
3702 if (!single_pred_p (else_bb))
3705 /* THEN is not EXIT. */
3706 if (then_bb->index < NUM_FIXED_BLOCKS)
3709 /* ELSE is predicted or SUCC(ELSE) postdominates THEN. */
3710 note = find_reg_note (BB_END (test_bb), REG_BR_PROB, NULL_RTX);
3711 if (note && INTVAL (XEXP (note, 0)) >= REG_BR_PROB_BASE / 2)
3713 else if (else_succ->dest->index < NUM_FIXED_BLOCKS
3714 || dominated_by_p (CDI_POST_DOMINATORS, then_bb,
3720 num_possible_if_blocks++;
3723 "\nIF-CASE-2 found, start %d, else %d\n",
3724 test_bb->index, else_bb->index);
3726 /* ELSE is small. */
3727 if (! cheap_bb_rtx_cost_p (else_bb,
3728 COSTS_N_INSNS (BRANCH_COST (optimize_bb_for_speed_p (else_edge->src),
3729 predictable_edge_p (else_edge)))))
3732 /* Registers set are dead, or are predicable. */
3733 if (! dead_or_predicable (test_bb, else_bb, then_bb, else_succ->dest, 0))
3736 /* Conversion went ok, including moving the insns and fixing up the
3737 jump. Adjust the CFG to match. */
3739 df_set_bb_dirty (test_bb);
3740 df_set_bb_dirty (then_bb);
3741 delete_basic_block (else_bb);
3744 num_updated_if_blocks++;
3746 /* ??? We may now fallthru from one of THEN's successors into a join
3747 block. Rerun cleanup_cfg? Examine things manually? Wait? */
3752 /* A subroutine of dead_or_predicable called through for_each_rtx.
3753 Return 1 if a memory is found. */
3756 find_memory (rtx *px, void *data ATTRIBUTE_UNUSED)
3761 /* Used by the code above to perform the actual rtl transformations.
3762 Return TRUE if successful.
3764 TEST_BB is the block containing the conditional branch. MERGE_BB
3765 is the block containing the code to manipulate. NEW_DEST is the
3766 label TEST_BB should be branching to after the conversion.
3767 REVERSEP is true if the sense of the branch should be reversed. */
3770 dead_or_predicable (basic_block test_bb, basic_block merge_bb,
3771 basic_block other_bb, basic_block new_dest, int reversep)
3773 rtx head, end, jump, earliest = NULL_RTX, old_dest, new_label = NULL_RTX;
3775 jump = BB_END (test_bb);
3777 /* Find the extent of the real code in the merge block. */
3778 head = BB_HEAD (merge_bb);
3779 end = BB_END (merge_bb);
3781 /* If merge_bb ends with a tablejump, predicating/moving insn's
3782 into test_bb and then deleting merge_bb will result in the jumptable
3783 that follows merge_bb being removed along with merge_bb and then we
3784 get an unresolved reference to the jumptable. */
3785 if (tablejump_p (end, NULL, NULL))
3789 head = NEXT_INSN (head);
3794 head = end = NULL_RTX;
3797 head = NEXT_INSN (head);
3804 head = end = NULL_RTX;
3807 end = PREV_INSN (end);
3810 /* Disable handling dead code by conditional execution if the machine needs
3811 to do anything funny with the tests, etc. */
3812 #ifndef IFCVT_MODIFY_TESTS
3813 if (HAVE_conditional_execution)
3815 /* In the conditional execution case, we have things easy. We know
3816 the condition is reversible. We don't have to check life info
3817 because we're going to conditionally execute the code anyway.
3818 All that's left is making sure the insns involved can actually
3823 cond = cond_exec_get_condition (jump);
3827 prob_val = find_reg_note (jump, REG_BR_PROB, NULL_RTX);
3829 prob_val = XEXP (prob_val, 0);
3833 enum rtx_code rev = reversed_comparison_code (cond, jump);
3836 cond = gen_rtx_fmt_ee (rev, GET_MODE (cond), XEXP (cond, 0),
3839 prob_val = GEN_INT (REG_BR_PROB_BASE - INTVAL (prob_val));
3842 if (! cond_exec_process_insns ((ce_if_block_t *)0, head, end, cond,
3851 /* In the non-conditional execution case, we have to verify that there
3852 are no trapping operations, no calls, no references to memory, and
3853 that any registers modified are dead at the branch site. */
3855 rtx insn, cond, prev;
3856 bitmap merge_set, test_live, test_set;
3857 unsigned i, fail = 0;
3860 /* Check for no calls or trapping operations. */
3861 for (insn = head; ; insn = NEXT_INSN (insn))
3867 if (may_trap_p (PATTERN (insn)))
3870 /* ??? Even non-trapping memories such as stack frame
3871 references must be avoided. For stores, we collect
3872 no lifetime info; for reads, we'd have to assert
3873 true_dependence false against every store in the
3875 if (for_each_rtx (&PATTERN (insn), find_memory, NULL))
3882 if (! any_condjump_p (jump))
3885 /* Find the extent of the conditional. */
3886 cond = noce_get_condition (jump, &earliest, false);
3891 MERGE_SET = set of registers set in MERGE_BB
3892 TEST_LIVE = set of registers live at EARLIEST
3893 TEST_SET = set of registers set between EARLIEST and the
3894 end of the block. */
3896 merge_set = BITMAP_ALLOC (®_obstack);
3897 test_live = BITMAP_ALLOC (®_obstack);
3898 test_set = BITMAP_ALLOC (®_obstack);
3900 /* ??? bb->local_set is only valid during calculate_global_regs_live,
3901 so we must recompute usage for MERGE_BB. Not so bad, I suppose,
3902 since we've already asserted that MERGE_BB is small. */
3903 /* If we allocated new pseudos (e.g. in the conditional move
3904 expander called from noce_emit_cmove), we must resize the
3906 if (max_regno < max_reg_num ())
3907 max_regno = max_reg_num ();
3909 FOR_BB_INSNS (merge_bb, insn)
3913 unsigned int uid = INSN_UID (insn);
3914 struct df_ref **def_rec;
3915 for (def_rec = DF_INSN_UID_DEFS (uid); *def_rec; def_rec++)
3917 struct df_ref *def = *def_rec;
3918 bitmap_set_bit (merge_set, DF_REF_REGNO (def));
3923 /* For small register class machines, don't lengthen lifetimes of
3924 hard registers before reload. */
3925 if (SMALL_REGISTER_CLASSES && ! reload_completed)
3927 EXECUTE_IF_SET_IN_BITMAP (merge_set, 0, i, bi)
3929 if (i < FIRST_PSEUDO_REGISTER
3931 && ! global_regs[i])
3936 /* For TEST, we're interested in a range of insns, not a whole block.
3937 Moreover, we're interested in the insns live from OTHER_BB. */
3939 /* The loop below takes the set of live registers
3940 after JUMP, and calculates the live set before EARLIEST. */
3941 bitmap_copy (test_live, df_get_live_in (other_bb));
3942 df_simulate_artificial_refs_at_end (test_bb, test_live);
3943 for (insn = jump; ; insn = prev)
3947 df_simulate_find_defs (insn, test_set);
3948 df_simulate_one_insn (test_bb, insn, test_live);
3950 prev = PREV_INSN (insn);
3951 if (insn == earliest)
3955 /* We can perform the transformation if
3956 MERGE_SET & (TEST_SET | TEST_LIVE)
3958 TEST_SET & DF_LIVE_IN (merge_bb)
3961 if (bitmap_intersect_p (test_set, merge_set)
3962 || bitmap_intersect_p (test_live, merge_set)
3963 || bitmap_intersect_p (test_set, df_get_live_in (merge_bb)))
3966 BITMAP_FREE (merge_set);
3967 BITMAP_FREE (test_live);
3968 BITMAP_FREE (test_set);
3975 /* We don't want to use normal invert_jump or redirect_jump because
3976 we don't want to delete_insn called. Also, we want to do our own
3977 change group management. */
3979 old_dest = JUMP_LABEL (jump);
3980 if (other_bb != new_dest)
3982 new_label = block_label (new_dest);
3984 ? ! invert_jump_1 (jump, new_label)
3985 : ! redirect_jump_1 (jump, new_label))
3989 if (! apply_change_group ())
3992 if (other_bb != new_dest)
3994 redirect_jump_2 (jump, old_dest, new_label, 0, reversep);
3996 redirect_edge_succ (BRANCH_EDGE (test_bb), new_dest);
3999 gcov_type count, probability;
4000 count = BRANCH_EDGE (test_bb)->count;
4001 BRANCH_EDGE (test_bb)->count = FALLTHRU_EDGE (test_bb)->count;
4002 FALLTHRU_EDGE (test_bb)->count = count;
4003 probability = BRANCH_EDGE (test_bb)->probability;
4004 BRANCH_EDGE (test_bb)->probability
4005 = FALLTHRU_EDGE (test_bb)->probability;
4006 FALLTHRU_EDGE (test_bb)->probability = probability;
4007 update_br_prob_note (test_bb);
4011 /* Move the insns out of MERGE_BB to before the branch. */
4016 if (end == BB_END (merge_bb))
4017 BB_END (merge_bb) = PREV_INSN (head);
4019 /* PR 21767: When moving insns above a conditional branch, REG_EQUAL
4020 notes might become invalid. */
4026 if (! INSN_P (insn))
4028 note = find_reg_note (insn, REG_EQUAL, NULL_RTX);
4031 set = single_set (insn);
4032 if (!set || !function_invariant_p (SET_SRC (set)))
4033 remove_note (insn, note);
4034 } while (insn != end && (insn = NEXT_INSN (insn)));
4036 reorder_insns (head, end, PREV_INSN (earliest));
4039 /* Remove the jump and edge if we can. */
4040 if (other_bb == new_dest)
4043 remove_edge (BRANCH_EDGE (test_bb));
4044 /* ??? Can't merge blocks here, as then_bb is still in use.
4045 At minimum, the merge will get done just before bb-reorder. */
4055 /* Main entry point for all if-conversion. */
4065 df_live_add_problem ();
4066 df_live_set_all_dirty ();
4069 num_possible_if_blocks = 0;
4070 num_updated_if_blocks = 0;
4071 num_true_changes = 0;
4073 loop_optimizer_init (AVOID_CFG_MODIFICATIONS);
4074 mark_loop_exit_edges ();
4075 loop_optimizer_finalize ();
4076 free_dominance_info (CDI_DOMINATORS);
4078 /* Compute postdominators. */
4079 calculate_dominance_info (CDI_POST_DOMINATORS);
4081 df_set_flags (DF_LR_RUN_DCE);
4083 /* Go through each of the basic blocks looking for things to convert. If we
4084 have conditional execution, we make multiple passes to allow us to handle
4085 IF-THEN{-ELSE} blocks within other IF-THEN{-ELSE} blocks. */
4090 /* Only need to do dce on the first pass. */
4091 df_clear_flags (DF_LR_RUN_DCE);
4092 cond_exec_changed_p = FALSE;
4095 #ifdef IFCVT_MULTIPLE_DUMPS
4096 if (dump_file && pass > 1)
4097 fprintf (dump_file, "\n\n========== Pass %d ==========\n", pass);
4103 while (!df_get_bb_dirty (bb)
4104 && (new_bb = find_if_header (bb, pass)) != NULL)
4108 #ifdef IFCVT_MULTIPLE_DUMPS
4109 if (dump_file && cond_exec_changed_p)
4110 print_rtl_with_bb (dump_file, get_insns ());
4113 while (cond_exec_changed_p);
4115 #ifdef IFCVT_MULTIPLE_DUMPS
4117 fprintf (dump_file, "\n\n========== no more changes\n");
4120 free_dominance_info (CDI_POST_DOMINATORS);
4125 clear_aux_for_blocks ();
4127 /* If we allocated new pseudos, we must resize the array for sched1. */
4128 if (max_regno < max_reg_num ())
4129 max_regno = max_reg_num ();
4131 /* Write the final stats. */
4132 if (dump_file && num_possible_if_blocks > 0)
4135 "\n%d possible IF blocks searched.\n",
4136 num_possible_if_blocks);
4138 "%d IF blocks converted.\n",
4139 num_updated_if_blocks);
4141 "%d true changes made.\n\n\n",
4146 df_remove_problem (df_live);
4148 #ifdef ENABLE_CHECKING
4149 verify_flow_info ();
4154 gate_handle_if_conversion (void)
4156 return (optimize > 0)
4157 && dbg_cnt (if_conversion);
4160 /* If-conversion and CFG cleanup. */
4162 rest_of_handle_if_conversion (void)
4164 if (flag_if_conversion)
4167 dump_flow_info (dump_file, dump_flags);
4168 cleanup_cfg (CLEANUP_EXPENSIVE);
4176 struct rtl_opt_pass pass_rtl_ifcvt =
4181 gate_handle_if_conversion, /* gate */
4182 rest_of_handle_if_conversion, /* execute */
4185 0, /* static_pass_number */
4186 TV_IFCVT, /* tv_id */
4187 0, /* properties_required */
4188 0, /* properties_provided */
4189 0, /* properties_destroyed */
4190 0, /* todo_flags_start */
4191 TODO_df_finish | TODO_verify_rtl_sharing |
4192 TODO_dump_func /* todo_flags_finish */
4197 gate_handle_if_after_combine (void)
4199 return optimize > 0 && flag_if_conversion
4200 && dbg_cnt (if_after_combine);
4204 /* Rerun if-conversion, as combine may have simplified things enough
4205 to now meet sequence length restrictions. */
4207 rest_of_handle_if_after_combine (void)
4213 struct rtl_opt_pass pass_if_after_combine =
4218 gate_handle_if_after_combine, /* gate */
4219 rest_of_handle_if_after_combine, /* execute */
4222 0, /* static_pass_number */
4223 TV_IFCVT, /* tv_id */
4224 0, /* properties_required */
4225 0, /* properties_provided */
4226 0, /* properties_destroyed */
4227 0, /* todo_flags_start */
4228 TODO_df_finish | TODO_verify_rtl_sharing |
4230 TODO_ggc_collect /* todo_flags_finish */
4236 gate_handle_if_after_reload (void)
4238 return optimize > 0 && flag_if_conversion2
4239 && dbg_cnt (if_after_reload);
4243 rest_of_handle_if_after_reload (void)
4250 struct rtl_opt_pass pass_if_after_reload =
4255 gate_handle_if_after_reload, /* gate */
4256 rest_of_handle_if_after_reload, /* execute */
4259 0, /* static_pass_number */
4260 TV_IFCVT2, /* tv_id */
4261 0, /* properties_required */
4262 0, /* properties_provided */
4263 0, /* properties_destroyed */
4264 0, /* todo_flags_start */
4265 TODO_df_finish | TODO_verify_rtl_sharing |
4267 TODO_ggc_collect /* todo_flags_finish */