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"
49 #ifndef HAVE_conditional_execution
50 #define HAVE_conditional_execution 0
52 #ifndef HAVE_conditional_move
53 #define HAVE_conditional_move 0
64 #ifndef HAVE_conditional_trap
65 #define HAVE_conditional_trap 0
68 #ifndef MAX_CONDITIONAL_EXECUTE
69 #define MAX_CONDITIONAL_EXECUTE (BRANCH_COST + 1)
72 #define IFCVT_MULTIPLE_DUMPS 1
74 #define NULL_BLOCK ((basic_block) NULL)
76 /* # of IF-THEN or IF-THEN-ELSE blocks we looked at */
77 static int num_possible_if_blocks;
79 /* # of IF-THEN or IF-THEN-ELSE blocks were converted to conditional
81 static int num_updated_if_blocks;
83 /* # of changes made. */
84 static int num_true_changes;
86 /* Whether conditional execution changes were made. */
87 static int cond_exec_changed_p;
89 /* Forward references. */
90 static int count_bb_insns (const_basic_block);
91 static bool cheap_bb_rtx_cost_p (const_basic_block, int);
92 static rtx first_active_insn (basic_block);
93 static rtx last_active_insn (basic_block, int);
94 static basic_block block_fallthru (basic_block);
95 static int cond_exec_process_insns (ce_if_block_t *, rtx, rtx, rtx, rtx, int);
96 static rtx cond_exec_get_condition (rtx);
97 static rtx noce_get_condition (rtx, rtx *, bool);
98 static int noce_operand_ok (const_rtx);
99 static void merge_if_block (ce_if_block_t *);
100 static int find_cond_trap (basic_block, edge, edge);
101 static basic_block find_if_header (basic_block, int);
102 static int block_jumps_and_fallthru_p (basic_block, basic_block);
103 static int noce_find_if_block (basic_block, edge, edge, int);
104 static int cond_exec_find_if_block (ce_if_block_t *);
105 static int find_if_case_1 (basic_block, edge, edge);
106 static int find_if_case_2 (basic_block, edge, edge);
107 static int find_memory (rtx *, void *);
108 static int dead_or_predicable (basic_block, basic_block, basic_block,
110 static void noce_emit_move_insn (rtx, rtx);
111 static rtx block_has_only_trap (basic_block);
113 /* Count the number of non-jump active insns in BB. */
116 count_bb_insns (const_basic_block bb)
119 rtx insn = BB_HEAD (bb);
123 if (CALL_P (insn) || NONJUMP_INSN_P (insn))
126 if (insn == BB_END (bb))
128 insn = NEXT_INSN (insn);
134 /* Determine whether the total insn_rtx_cost on non-jump insns in
135 basic block BB is less than MAX_COST. This function returns
136 false if the cost of any instruction could not be estimated. */
139 cheap_bb_rtx_cost_p (const_basic_block bb, int max_cost)
142 rtx insn = BB_HEAD (bb);
146 if (NONJUMP_INSN_P (insn))
148 int cost = insn_rtx_cost (PATTERN (insn));
152 /* If this instruction is the load or set of a "stack" register,
153 such as a floating point register on x87, then the cost of
154 speculatively executing this insn may need to include
155 the additional cost of popping its result off of the
156 register stack. Unfortunately, correctly recognizing and
157 accounting for this additional overhead is tricky, so for
158 now we simply prohibit such speculative execution. */
161 rtx set = single_set (insn);
162 if (set && STACK_REG_P (SET_DEST (set)))
168 if (count >= max_cost)
171 else if (CALL_P (insn))
174 if (insn == BB_END (bb))
176 insn = NEXT_INSN (insn);
182 /* Return the first non-jump active insn in the basic block. */
185 first_active_insn (basic_block bb)
187 rtx insn = BB_HEAD (bb);
191 if (insn == BB_END (bb))
193 insn = NEXT_INSN (insn);
196 while (NOTE_P (insn))
198 if (insn == BB_END (bb))
200 insn = NEXT_INSN (insn);
209 /* Return the last non-jump active (non-jump) insn in the basic block. */
212 last_active_insn (basic_block bb, int skip_use_p)
214 rtx insn = BB_END (bb);
215 rtx head = BB_HEAD (bb);
220 && NONJUMP_INSN_P (insn)
221 && GET_CODE (PATTERN (insn)) == USE))
225 insn = PREV_INSN (insn);
234 /* Return the basic block reached by falling though the basic block BB. */
237 block_fallthru (basic_block bb)
242 FOR_EACH_EDGE (e, ei, bb->succs)
243 if (e->flags & EDGE_FALLTHRU)
246 return (e) ? e->dest : NULL_BLOCK;
249 /* Go through a bunch of insns, converting them to conditional
250 execution format if possible. Return TRUE if all of the non-note
251 insns were processed. */
254 cond_exec_process_insns (ce_if_block_t *ce_info ATTRIBUTE_UNUSED,
255 /* if block information */rtx start,
256 /* first insn to look at */rtx end,
257 /* last insn to look at */rtx test,
258 /* conditional execution test */rtx prob_val,
259 /* probability of branch taken. */int mod_ok)
261 int must_be_last = FALSE;
269 for (insn = start; ; insn = NEXT_INSN (insn))
274 gcc_assert(NONJUMP_INSN_P (insn) || CALL_P (insn));
276 /* Remove USE insns that get in the way. */
277 if (reload_completed && GET_CODE (PATTERN (insn)) == USE)
279 /* ??? Ug. Actually unlinking the thing is problematic,
280 given what we'd have to coordinate with our callers. */
281 SET_INSN_DELETED (insn);
285 /* Last insn wasn't last? */
289 if (modified_in_p (test, insn))
296 /* Now build the conditional form of the instruction. */
297 pattern = PATTERN (insn);
298 xtest = copy_rtx (test);
300 /* If this is already a COND_EXEC, rewrite the test to be an AND of the
302 if (GET_CODE (pattern) == COND_EXEC)
304 if (GET_MODE (xtest) != GET_MODE (COND_EXEC_TEST (pattern)))
307 xtest = gen_rtx_AND (GET_MODE (xtest), xtest,
308 COND_EXEC_TEST (pattern));
309 pattern = COND_EXEC_CODE (pattern);
312 pattern = gen_rtx_COND_EXEC (VOIDmode, xtest, pattern);
314 /* If the machine needs to modify the insn being conditionally executed,
315 say for example to force a constant integer operand into a temp
316 register, do so here. */
317 #ifdef IFCVT_MODIFY_INSN
318 IFCVT_MODIFY_INSN (ce_info, pattern, insn);
323 validate_change (insn, &PATTERN (insn), pattern, 1);
325 if (CALL_P (insn) && prob_val)
326 validate_change (insn, ®_NOTES (insn),
327 alloc_EXPR_LIST (REG_BR_PROB, prob_val,
328 REG_NOTES (insn)), 1);
338 /* Return the condition for a jump. Do not do any special processing. */
341 cond_exec_get_condition (rtx jump)
345 if (any_condjump_p (jump))
346 test_if = SET_SRC (pc_set (jump));
349 cond = XEXP (test_if, 0);
351 /* If this branches to JUMP_LABEL when the condition is false,
352 reverse the condition. */
353 if (GET_CODE (XEXP (test_if, 2)) == LABEL_REF
354 && XEXP (XEXP (test_if, 2), 0) == JUMP_LABEL (jump))
356 enum rtx_code rev = reversed_comparison_code (cond, jump);
360 cond = gen_rtx_fmt_ee (rev, GET_MODE (cond), XEXP (cond, 0),
367 /* Given a simple IF-THEN or IF-THEN-ELSE block, attempt to convert it
368 to conditional execution. Return TRUE if we were successful at
369 converting the block. */
372 cond_exec_process_if_block (ce_if_block_t * ce_info,
373 /* if block information */int do_multiple_p)
375 basic_block test_bb = ce_info->test_bb; /* last test block */
376 basic_block then_bb = ce_info->then_bb; /* THEN */
377 basic_block else_bb = ce_info->else_bb; /* ELSE or NULL */
378 rtx test_expr; /* expression in IF_THEN_ELSE that is tested */
379 rtx then_start; /* first insn in THEN block */
380 rtx then_end; /* last insn + 1 in THEN block */
381 rtx else_start = NULL_RTX; /* first insn in ELSE block or NULL */
382 rtx else_end = NULL_RTX; /* last insn + 1 in ELSE block */
383 int max; /* max # of insns to convert. */
384 int then_mod_ok; /* whether conditional mods are ok in THEN */
385 rtx true_expr; /* test for else block insns */
386 rtx false_expr; /* test for then block insns */
387 rtx true_prob_val; /* probability of else block */
388 rtx false_prob_val; /* probability of then block */
390 enum rtx_code false_code;
392 /* If test is comprised of && or || elements, and we've failed at handling
393 all of them together, just use the last test if it is the special case of
394 && elements without an ELSE block. */
395 if (!do_multiple_p && ce_info->num_multiple_test_blocks)
397 if (else_bb || ! ce_info->and_and_p)
400 ce_info->test_bb = test_bb = ce_info->last_test_bb;
401 ce_info->num_multiple_test_blocks = 0;
402 ce_info->num_and_and_blocks = 0;
403 ce_info->num_or_or_blocks = 0;
406 /* Find the conditional jump to the ELSE or JOIN part, and isolate
408 test_expr = cond_exec_get_condition (BB_END (test_bb));
412 /* If the conditional jump is more than just a conditional jump,
413 then we can not do conditional execution conversion on this block. */
414 if (! onlyjump_p (BB_END (test_bb)))
417 /* Collect the bounds of where we're to search, skipping any labels, jumps
418 and notes at the beginning and end of the block. Then count the total
419 number of insns and see if it is small enough to convert. */
420 then_start = first_active_insn (then_bb);
421 then_end = last_active_insn (then_bb, TRUE);
422 n_insns = ce_info->num_then_insns = count_bb_insns (then_bb);
423 max = MAX_CONDITIONAL_EXECUTE;
428 else_start = first_active_insn (else_bb);
429 else_end = last_active_insn (else_bb, TRUE);
430 n_insns += ce_info->num_else_insns = count_bb_insns (else_bb);
436 /* Map test_expr/test_jump into the appropriate MD tests to use on
437 the conditionally executed code. */
439 true_expr = test_expr;
441 false_code = reversed_comparison_code (true_expr, BB_END (test_bb));
442 if (false_code != UNKNOWN)
443 false_expr = gen_rtx_fmt_ee (false_code, GET_MODE (true_expr),
444 XEXP (true_expr, 0), XEXP (true_expr, 1));
446 false_expr = NULL_RTX;
448 #ifdef IFCVT_MODIFY_TESTS
449 /* If the machine description needs to modify the tests, such as setting a
450 conditional execution register from a comparison, it can do so here. */
451 IFCVT_MODIFY_TESTS (ce_info, true_expr, false_expr);
453 /* See if the conversion failed. */
454 if (!true_expr || !false_expr)
458 true_prob_val = find_reg_note (BB_END (test_bb), REG_BR_PROB, NULL_RTX);
461 true_prob_val = XEXP (true_prob_val, 0);
462 false_prob_val = GEN_INT (REG_BR_PROB_BASE - INTVAL (true_prob_val));
465 false_prob_val = NULL_RTX;
467 /* If we have && or || tests, do them here. These tests are in the adjacent
468 blocks after the first block containing the test. */
469 if (ce_info->num_multiple_test_blocks > 0)
471 basic_block bb = test_bb;
472 basic_block last_test_bb = ce_info->last_test_bb;
481 enum rtx_code f_code;
483 bb = block_fallthru (bb);
484 start = first_active_insn (bb);
485 end = last_active_insn (bb, TRUE);
487 && ! cond_exec_process_insns (ce_info, start, end, false_expr,
488 false_prob_val, FALSE))
491 /* If the conditional jump is more than just a conditional jump, then
492 we can not do conditional execution conversion on this block. */
493 if (! onlyjump_p (BB_END (bb)))
496 /* Find the conditional jump and isolate the test. */
497 t = cond_exec_get_condition (BB_END (bb));
501 f_code = reversed_comparison_code (t, BB_END (bb));
502 if (f_code == UNKNOWN)
505 f = gen_rtx_fmt_ee (f_code, GET_MODE (t), XEXP (t, 0), XEXP (t, 1));
506 if (ce_info->and_and_p)
508 t = gen_rtx_AND (GET_MODE (t), true_expr, t);
509 f = gen_rtx_IOR (GET_MODE (t), false_expr, f);
513 t = gen_rtx_IOR (GET_MODE (t), true_expr, t);
514 f = gen_rtx_AND (GET_MODE (t), false_expr, f);
517 /* If the machine description needs to modify the tests, such as
518 setting a conditional execution register from a comparison, it can
520 #ifdef IFCVT_MODIFY_MULTIPLE_TESTS
521 IFCVT_MODIFY_MULTIPLE_TESTS (ce_info, bb, t, f);
523 /* See if the conversion failed. */
531 while (bb != last_test_bb);
534 /* For IF-THEN-ELSE blocks, we don't allow modifications of the test
535 on then THEN block. */
536 then_mod_ok = (else_bb == NULL_BLOCK);
538 /* Go through the THEN and ELSE blocks converting the insns if possible
539 to conditional execution. */
543 || ! cond_exec_process_insns (ce_info, then_start, then_end,
544 false_expr, false_prob_val,
548 if (else_bb && else_end
549 && ! cond_exec_process_insns (ce_info, else_start, else_end,
550 true_expr, true_prob_val, TRUE))
553 /* If we cannot apply the changes, fail. Do not go through the normal fail
554 processing, since apply_change_group will call cancel_changes. */
555 if (! apply_change_group ())
557 #ifdef IFCVT_MODIFY_CANCEL
558 /* Cancel any machine dependent changes. */
559 IFCVT_MODIFY_CANCEL (ce_info);
564 #ifdef IFCVT_MODIFY_FINAL
565 /* Do any machine dependent final modifications. */
566 IFCVT_MODIFY_FINAL (ce_info);
569 /* Conversion succeeded. */
571 fprintf (dump_file, "%d insn%s converted to conditional execution.\n",
572 n_insns, (n_insns == 1) ? " was" : "s were");
574 /* Merge the blocks! */
575 merge_if_block (ce_info);
576 cond_exec_changed_p = TRUE;
580 #ifdef IFCVT_MODIFY_CANCEL
581 /* Cancel any machine dependent changes. */
582 IFCVT_MODIFY_CANCEL (ce_info);
589 /* Used by noce_process_if_block to communicate with its subroutines.
591 The subroutines know that A and B may be evaluated freely. They
592 know that X is a register. They should insert new instructions
593 before cond_earliest. */
597 /* The basic blocks that make up the IF-THEN-{ELSE-,}JOIN block. */
598 basic_block test_bb, then_bb, else_bb, join_bb;
600 /* The jump that ends TEST_BB. */
603 /* The jump condition. */
606 /* New insns should be inserted before this one. */
609 /* Insns in the THEN and ELSE block. There is always just this
610 one insns in those blocks. The insns are single_set insns.
611 If there was no ELSE block, INSN_B is the last insn before
612 COND_EARLIEST, or NULL_RTX. In the former case, the insn
613 operands are still valid, as if INSN_B was moved down below
617 /* The SET_SRC of INSN_A and INSN_B. */
620 /* The SET_DEST of INSN_A. */
623 /* True if this if block is not canonical. In the canonical form of
624 if blocks, the THEN_BB is the block reached via the fallthru edge
625 from TEST_BB. For the noce transformations, we allow the symmetric
627 bool then_else_reversed;
630 static rtx noce_emit_store_flag (struct noce_if_info *, rtx, int, int);
631 static int noce_try_move (struct noce_if_info *);
632 static int noce_try_store_flag (struct noce_if_info *);
633 static int noce_try_addcc (struct noce_if_info *);
634 static int noce_try_store_flag_constants (struct noce_if_info *);
635 static int noce_try_store_flag_mask (struct noce_if_info *);
636 static rtx noce_emit_cmove (struct noce_if_info *, rtx, enum rtx_code, rtx,
638 static int noce_try_cmove (struct noce_if_info *);
639 static int noce_try_cmove_arith (struct noce_if_info *);
640 static rtx noce_get_alt_condition (struct noce_if_info *, rtx, rtx *);
641 static int noce_try_minmax (struct noce_if_info *);
642 static int noce_try_abs (struct noce_if_info *);
643 static int noce_try_sign_mask (struct noce_if_info *);
645 /* Helper function for noce_try_store_flag*. */
648 noce_emit_store_flag (struct noce_if_info *if_info, rtx x, int reversep,
651 rtx cond = if_info->cond;
655 cond_complex = (! general_operand (XEXP (cond, 0), VOIDmode)
656 || ! general_operand (XEXP (cond, 1), VOIDmode));
658 /* If earliest == jump, or when the condition is complex, try to
659 build the store_flag insn directly. */
662 cond = XEXP (SET_SRC (pc_set (if_info->jump)), 0);
665 code = reversed_comparison_code (cond, if_info->jump);
667 code = GET_CODE (cond);
669 if ((if_info->cond_earliest == if_info->jump || cond_complex)
670 && (normalize == 0 || STORE_FLAG_VALUE == normalize))
674 tmp = gen_rtx_fmt_ee (code, GET_MODE (x), XEXP (cond, 0),
676 tmp = gen_rtx_SET (VOIDmode, x, tmp);
679 tmp = emit_insn (tmp);
681 if (recog_memoized (tmp) >= 0)
687 if_info->cond_earliest = if_info->jump;
695 /* Don't even try if the comparison operands or the mode of X are weird. */
696 if (cond_complex || !SCALAR_INT_MODE_P (GET_MODE (x)))
699 return emit_store_flag (x, code, XEXP (cond, 0),
700 XEXP (cond, 1), VOIDmode,
701 (code == LTU || code == LEU
702 || code == GEU || code == GTU), normalize);
705 /* Emit instruction to move an rtx, possibly into STRICT_LOW_PART.
706 X is the destination/target and Y is the value to copy. */
709 noce_emit_move_insn (rtx x, rtx y)
711 enum machine_mode outmode;
715 if (GET_CODE (x) != STRICT_LOW_PART)
717 rtx seq, insn, target;
721 /* Check that the SET_SRC is reasonable before calling emit_move_insn,
722 otherwise construct a suitable SET pattern ourselves. */
723 insn = (OBJECT_P (y) || CONSTANT_P (y) || GET_CODE (y) == SUBREG)
724 ? emit_move_insn (x, y)
725 : emit_insn (gen_rtx_SET (VOIDmode, x, y));
729 if (recog_memoized (insn) <= 0)
731 if (GET_CODE (x) == ZERO_EXTRACT)
733 rtx op = XEXP (x, 0);
734 unsigned HOST_WIDE_INT size = INTVAL (XEXP (x, 1));
735 unsigned HOST_WIDE_INT start = INTVAL (XEXP (x, 2));
737 /* store_bit_field expects START to be relative to
738 BYTES_BIG_ENDIAN and adjusts this value for machines with
739 BITS_BIG_ENDIAN != BYTES_BIG_ENDIAN. In order to be able to
740 invoke store_bit_field again it is necessary to have the START
741 value from the first call. */
742 if (BITS_BIG_ENDIAN != BYTES_BIG_ENDIAN)
745 start = BITS_PER_UNIT - start - size;
748 gcc_assert (REG_P (op));
749 start = BITS_PER_WORD - start - size;
753 gcc_assert (start < (MEM_P (op) ? BITS_PER_UNIT : BITS_PER_WORD));
754 store_bit_field (op, size, start, GET_MODE (x), y);
758 switch (GET_RTX_CLASS (GET_CODE (y)))
761 ot = code_to_optab[GET_CODE (y)];
765 target = expand_unop (GET_MODE (y), ot, XEXP (y, 0), x, 0);
766 if (target != NULL_RTX)
769 emit_move_insn (x, target);
778 ot = code_to_optab[GET_CODE (y)];
782 target = expand_binop (GET_MODE (y), ot,
783 XEXP (y, 0), XEXP (y, 1),
785 if (target != NULL_RTX)
788 emit_move_insn (x, target);
805 inner = XEXP (outer, 0);
806 outmode = GET_MODE (outer);
807 bitpos = SUBREG_BYTE (outer) * BITS_PER_UNIT;
808 store_bit_field (inner, GET_MODE_BITSIZE (outmode), bitpos, outmode, y);
811 /* Return sequence of instructions generated by if conversion. This
812 function calls end_sequence() to end the current stream, ensures
813 that are instructions are unshared, recognizable non-jump insns.
814 On failure, this function returns a NULL_RTX. */
817 end_ifcvt_sequence (struct noce_if_info *if_info)
820 rtx seq = get_insns ();
822 set_used_flags (if_info->x);
823 set_used_flags (if_info->cond);
824 unshare_all_rtl_in_chain (seq);
827 /* Make sure that all of the instructions emitted are recognizable,
828 and that we haven't introduced a new jump instruction.
829 As an exercise for the reader, build a general mechanism that
830 allows proper placement of required clobbers. */
831 for (insn = seq; insn; insn = NEXT_INSN (insn))
833 || recog_memoized (insn) == -1)
839 /* Convert "if (a != b) x = a; else x = b" into "x = a" and
840 "if (a == b) x = a; else x = b" into "x = b". */
843 noce_try_move (struct noce_if_info *if_info)
845 rtx cond = if_info->cond;
846 enum rtx_code code = GET_CODE (cond);
849 if (code != NE && code != EQ)
852 /* This optimization isn't valid if either A or B could be a NaN
854 if (HONOR_NANS (GET_MODE (if_info->x))
855 || HONOR_SIGNED_ZEROS (GET_MODE (if_info->x)))
858 /* Check whether the operands of the comparison are A and in
860 if ((rtx_equal_p (if_info->a, XEXP (cond, 0))
861 && rtx_equal_p (if_info->b, XEXP (cond, 1)))
862 || (rtx_equal_p (if_info->a, XEXP (cond, 1))
863 && rtx_equal_p (if_info->b, XEXP (cond, 0))))
865 y = (code == EQ) ? if_info->a : if_info->b;
867 /* Avoid generating the move if the source is the destination. */
868 if (! rtx_equal_p (if_info->x, y))
871 noce_emit_move_insn (if_info->x, y);
872 seq = end_ifcvt_sequence (if_info);
876 emit_insn_before_setloc (seq, if_info->jump,
877 INSN_LOCATOR (if_info->insn_a));
884 /* Convert "if (test) x = 1; else x = 0".
886 Only try 0 and STORE_FLAG_VALUE here. Other combinations will be
887 tried in noce_try_store_flag_constants after noce_try_cmove has had
888 a go at the conversion. */
891 noce_try_store_flag (struct noce_if_info *if_info)
896 if (GET_CODE (if_info->b) == CONST_INT
897 && INTVAL (if_info->b) == STORE_FLAG_VALUE
898 && if_info->a == const0_rtx)
900 else if (if_info->b == const0_rtx
901 && GET_CODE (if_info->a) == CONST_INT
902 && INTVAL (if_info->a) == STORE_FLAG_VALUE
903 && (reversed_comparison_code (if_info->cond, if_info->jump)
911 target = noce_emit_store_flag (if_info, if_info->x, reversep, 0);
914 if (target != if_info->x)
915 noce_emit_move_insn (if_info->x, target);
917 seq = end_ifcvt_sequence (if_info);
921 emit_insn_before_setloc (seq, if_info->jump,
922 INSN_LOCATOR (if_info->insn_a));
932 /* Convert "if (test) x = a; else x = b", for A and B constant. */
935 noce_try_store_flag_constants (struct noce_if_info *if_info)
939 HOST_WIDE_INT itrue, ifalse, diff, tmp;
940 int normalize, can_reverse;
941 enum machine_mode mode;
943 if (GET_CODE (if_info->a) == CONST_INT
944 && GET_CODE (if_info->b) == CONST_INT)
946 mode = GET_MODE (if_info->x);
947 ifalse = INTVAL (if_info->a);
948 itrue = INTVAL (if_info->b);
950 /* Make sure we can represent the difference between the two values. */
951 if ((itrue - ifalse > 0)
952 != ((ifalse < 0) != (itrue < 0) ? ifalse < 0 : ifalse < itrue))
955 diff = trunc_int_for_mode (itrue - ifalse, mode);
957 can_reverse = (reversed_comparison_code (if_info->cond, if_info->jump)
961 if (diff == STORE_FLAG_VALUE || diff == -STORE_FLAG_VALUE)
963 else if (ifalse == 0 && exact_log2 (itrue) >= 0
964 && (STORE_FLAG_VALUE == 1
965 || BRANCH_COST >= 2))
967 else if (itrue == 0 && exact_log2 (ifalse) >= 0 && can_reverse
968 && (STORE_FLAG_VALUE == 1 || BRANCH_COST >= 2))
969 normalize = 1, reversep = 1;
971 && (STORE_FLAG_VALUE == -1
972 || BRANCH_COST >= 2))
974 else if (ifalse == -1 && can_reverse
975 && (STORE_FLAG_VALUE == -1 || BRANCH_COST >= 2))
976 normalize = -1, reversep = 1;
977 else if ((BRANCH_COST >= 2 && STORE_FLAG_VALUE == -1)
985 tmp = itrue; itrue = ifalse; ifalse = tmp;
986 diff = trunc_int_for_mode (-diff, mode);
990 target = noce_emit_store_flag (if_info, if_info->x, reversep, normalize);
997 /* if (test) x = 3; else x = 4;
998 => x = 3 + (test == 0); */
999 if (diff == STORE_FLAG_VALUE || diff == -STORE_FLAG_VALUE)
1001 target = expand_simple_binop (mode,
1002 (diff == STORE_FLAG_VALUE
1004 GEN_INT (ifalse), target, if_info->x, 0,
1008 /* if (test) x = 8; else x = 0;
1009 => x = (test != 0) << 3; */
1010 else if (ifalse == 0 && (tmp = exact_log2 (itrue)) >= 0)
1012 target = expand_simple_binop (mode, ASHIFT,
1013 target, GEN_INT (tmp), if_info->x, 0,
1017 /* if (test) x = -1; else x = b;
1018 => x = -(test != 0) | b; */
1019 else if (itrue == -1)
1021 target = expand_simple_binop (mode, IOR,
1022 target, GEN_INT (ifalse), if_info->x, 0,
1026 /* if (test) x = a; else x = b;
1027 => x = (-(test != 0) & (b - a)) + a; */
1030 target = expand_simple_binop (mode, AND,
1031 target, GEN_INT (diff), if_info->x, 0,
1034 target = expand_simple_binop (mode, PLUS,
1035 target, GEN_INT (ifalse),
1036 if_info->x, 0, OPTAB_WIDEN);
1045 if (target != if_info->x)
1046 noce_emit_move_insn (if_info->x, target);
1048 seq = end_ifcvt_sequence (if_info);
1052 emit_insn_before_setloc (seq, if_info->jump,
1053 INSN_LOCATOR (if_info->insn_a));
1060 /* Convert "if (test) foo++" into "foo += (test != 0)", and
1061 similarly for "foo--". */
1064 noce_try_addcc (struct noce_if_info *if_info)
1067 int subtract, normalize;
1069 if (GET_CODE (if_info->a) == PLUS
1070 && rtx_equal_p (XEXP (if_info->a, 0), if_info->b)
1071 && (reversed_comparison_code (if_info->cond, if_info->jump)
1074 rtx cond = if_info->cond;
1075 enum rtx_code code = reversed_comparison_code (cond, if_info->jump);
1077 /* First try to use addcc pattern. */
1078 if (general_operand (XEXP (cond, 0), VOIDmode)
1079 && general_operand (XEXP (cond, 1), VOIDmode))
1082 target = emit_conditional_add (if_info->x, code,
1087 XEXP (if_info->a, 1),
1088 GET_MODE (if_info->x),
1089 (code == LTU || code == GEU
1090 || code == LEU || code == GTU));
1093 if (target != if_info->x)
1094 noce_emit_move_insn (if_info->x, target);
1096 seq = end_ifcvt_sequence (if_info);
1100 emit_insn_before_setloc (seq, if_info->jump,
1101 INSN_LOCATOR (if_info->insn_a));
1107 /* If that fails, construct conditional increment or decrement using
1109 if (BRANCH_COST >= 2
1110 && (XEXP (if_info->a, 1) == const1_rtx
1111 || XEXP (if_info->a, 1) == constm1_rtx))
1114 if (STORE_FLAG_VALUE == INTVAL (XEXP (if_info->a, 1)))
1115 subtract = 0, normalize = 0;
1116 else if (-STORE_FLAG_VALUE == INTVAL (XEXP (if_info->a, 1)))
1117 subtract = 1, normalize = 0;
1119 subtract = 0, normalize = INTVAL (XEXP (if_info->a, 1));
1122 target = noce_emit_store_flag (if_info,
1123 gen_reg_rtx (GET_MODE (if_info->x)),
1127 target = expand_simple_binop (GET_MODE (if_info->x),
1128 subtract ? MINUS : PLUS,
1129 if_info->b, target, if_info->x,
1133 if (target != if_info->x)
1134 noce_emit_move_insn (if_info->x, target);
1136 seq = end_ifcvt_sequence (if_info);
1140 emit_insn_before_setloc (seq, if_info->jump,
1141 INSN_LOCATOR (if_info->insn_a));
1151 /* Convert "if (test) x = 0;" to "x &= -(test == 0);" */
1154 noce_try_store_flag_mask (struct noce_if_info *if_info)
1160 if ((BRANCH_COST >= 2
1161 || STORE_FLAG_VALUE == -1)
1162 && ((if_info->a == const0_rtx
1163 && rtx_equal_p (if_info->b, if_info->x))
1164 || ((reversep = (reversed_comparison_code (if_info->cond,
1167 && if_info->b == const0_rtx
1168 && rtx_equal_p (if_info->a, if_info->x))))
1171 target = noce_emit_store_flag (if_info,
1172 gen_reg_rtx (GET_MODE (if_info->x)),
1175 target = expand_simple_binop (GET_MODE (if_info->x), AND,
1177 target, if_info->x, 0,
1182 if (target != if_info->x)
1183 noce_emit_move_insn (if_info->x, target);
1185 seq = end_ifcvt_sequence (if_info);
1189 emit_insn_before_setloc (seq, if_info->jump,
1190 INSN_LOCATOR (if_info->insn_a));
1200 /* Helper function for noce_try_cmove and noce_try_cmove_arith. */
1203 noce_emit_cmove (struct noce_if_info *if_info, rtx x, enum rtx_code code,
1204 rtx cmp_a, rtx cmp_b, rtx vfalse, rtx vtrue)
1206 /* If earliest == jump, try to build the cmove insn directly.
1207 This is helpful when combine has created some complex condition
1208 (like for alpha's cmovlbs) that we can't hope to regenerate
1209 through the normal interface. */
1211 if (if_info->cond_earliest == if_info->jump)
1215 tmp = gen_rtx_fmt_ee (code, GET_MODE (if_info->cond), cmp_a, cmp_b);
1216 tmp = gen_rtx_IF_THEN_ELSE (GET_MODE (x), tmp, vtrue, vfalse);
1217 tmp = gen_rtx_SET (VOIDmode, x, tmp);
1220 tmp = emit_insn (tmp);
1222 if (recog_memoized (tmp) >= 0)
1234 /* Don't even try if the comparison operands are weird. */
1235 if (! general_operand (cmp_a, GET_MODE (cmp_a))
1236 || ! general_operand (cmp_b, GET_MODE (cmp_b)))
1239 #if HAVE_conditional_move
1240 return emit_conditional_move (x, code, cmp_a, cmp_b, VOIDmode,
1241 vtrue, vfalse, GET_MODE (x),
1242 (code == LTU || code == GEU
1243 || code == LEU || code == GTU));
1245 /* We'll never get here, as noce_process_if_block doesn't call the
1246 functions involved. Ifdef code, however, should be discouraged
1247 because it leads to typos in the code not selected. However,
1248 emit_conditional_move won't exist either. */
1253 /* Try only simple constants and registers here. More complex cases
1254 are handled in noce_try_cmove_arith after noce_try_store_flag_arith
1255 has had a go at it. */
1258 noce_try_cmove (struct noce_if_info *if_info)
1263 if ((CONSTANT_P (if_info->a) || register_operand (if_info->a, VOIDmode))
1264 && (CONSTANT_P (if_info->b) || register_operand (if_info->b, VOIDmode)))
1268 code = GET_CODE (if_info->cond);
1269 target = noce_emit_cmove (if_info, if_info->x, code,
1270 XEXP (if_info->cond, 0),
1271 XEXP (if_info->cond, 1),
1272 if_info->a, if_info->b);
1276 if (target != if_info->x)
1277 noce_emit_move_insn (if_info->x, target);
1279 seq = end_ifcvt_sequence (if_info);
1283 emit_insn_before_setloc (seq, if_info->jump,
1284 INSN_LOCATOR (if_info->insn_a));
1297 /* Try more complex cases involving conditional_move. */
1300 noce_try_cmove_arith (struct noce_if_info *if_info)
1312 /* A conditional move from two memory sources is equivalent to a
1313 conditional on their addresses followed by a load. Don't do this
1314 early because it'll screw alias analysis. Note that we've
1315 already checked for no side effects. */
1316 /* ??? FIXME: Magic number 5. */
1317 if (cse_not_expected
1318 && MEM_P (a) && MEM_P (b)
1319 && BRANCH_COST >= 5)
1323 x = gen_reg_rtx (Pmode);
1327 /* ??? We could handle this if we knew that a load from A or B could
1328 not fault. This is also true if we've already loaded
1329 from the address along the path from ENTRY. */
1330 else if (may_trap_p (a) || may_trap_p (b))
1333 /* if (test) x = a + b; else x = c - d;
1340 code = GET_CODE (if_info->cond);
1341 insn_a = if_info->insn_a;
1342 insn_b = if_info->insn_b;
1344 /* Total insn_rtx_cost should be smaller than branch cost. Exit
1345 if insn_rtx_cost can't be estimated. */
1348 insn_cost = insn_rtx_cost (PATTERN (insn_a));
1349 if (insn_cost == 0 || insn_cost > COSTS_N_INSNS (BRANCH_COST))
1357 insn_cost += insn_rtx_cost (PATTERN (insn_b));
1358 if (insn_cost == 0 || insn_cost > COSTS_N_INSNS (BRANCH_COST))
1362 /* Possibly rearrange operands to make things come out more natural. */
1363 if (reversed_comparison_code (if_info->cond, if_info->jump) != UNKNOWN)
1366 if (rtx_equal_p (b, x))
1368 else if (general_operand (b, GET_MODE (b)))
1373 code = reversed_comparison_code (if_info->cond, if_info->jump);
1374 tmp = a, a = b, b = tmp;
1375 tmp = insn_a, insn_a = insn_b, insn_b = tmp;
1384 /* If either operand is complex, load it into a register first.
1385 The best way to do this is to copy the original insn. In this
1386 way we preserve any clobbers etc that the insn may have had.
1387 This is of course not possible in the IS_MEM case. */
1388 if (! general_operand (a, GET_MODE (a)))
1394 tmp = gen_reg_rtx (GET_MODE (a));
1395 tmp = emit_insn (gen_rtx_SET (VOIDmode, tmp, a));
1398 goto end_seq_and_fail;
1401 a = gen_reg_rtx (GET_MODE (a));
1402 tmp = copy_rtx (insn_a);
1403 set = single_set (tmp);
1405 tmp = emit_insn (PATTERN (tmp));
1407 if (recog_memoized (tmp) < 0)
1408 goto end_seq_and_fail;
1410 if (! general_operand (b, GET_MODE (b)))
1416 tmp = gen_reg_rtx (GET_MODE (b));
1417 tmp = gen_rtx_SET (VOIDmode, tmp, b);
1420 goto end_seq_and_fail;
1423 b = gen_reg_rtx (GET_MODE (b));
1424 tmp = copy_rtx (insn_b);
1425 set = single_set (tmp);
1427 tmp = PATTERN (tmp);
1430 /* If insn to set up A clobbers any registers B depends on, try to
1431 swap insn that sets up A with the one that sets up B. If even
1432 that doesn't help, punt. */
1433 last = get_last_insn ();
1434 if (last && modified_in_p (orig_b, last))
1436 tmp = emit_insn_before (tmp, get_insns ());
1437 if (modified_in_p (orig_a, tmp))
1438 goto end_seq_and_fail;
1441 tmp = emit_insn (tmp);
1443 if (recog_memoized (tmp) < 0)
1444 goto end_seq_and_fail;
1447 target = noce_emit_cmove (if_info, x, code, XEXP (if_info->cond, 0),
1448 XEXP (if_info->cond, 1), a, b);
1451 goto end_seq_and_fail;
1453 /* If we're handling a memory for above, emit the load now. */
1456 tmp = gen_rtx_MEM (GET_MODE (if_info->x), target);
1458 /* Copy over flags as appropriate. */
1459 if (MEM_VOLATILE_P (if_info->a) || MEM_VOLATILE_P (if_info->b))
1460 MEM_VOLATILE_P (tmp) = 1;
1461 if (MEM_IN_STRUCT_P (if_info->a) && MEM_IN_STRUCT_P (if_info->b))
1462 MEM_IN_STRUCT_P (tmp) = 1;
1463 if (MEM_SCALAR_P (if_info->a) && MEM_SCALAR_P (if_info->b))
1464 MEM_SCALAR_P (tmp) = 1;
1465 if (MEM_ALIAS_SET (if_info->a) == MEM_ALIAS_SET (if_info->b))
1466 set_mem_alias_set (tmp, MEM_ALIAS_SET (if_info->a));
1468 MIN (MEM_ALIGN (if_info->a), MEM_ALIGN (if_info->b)));
1470 noce_emit_move_insn (if_info->x, tmp);
1472 else if (target != x)
1473 noce_emit_move_insn (x, target);
1475 tmp = end_ifcvt_sequence (if_info);
1479 emit_insn_before_setloc (tmp, if_info->jump, INSN_LOCATOR (if_info->insn_a));
1487 /* For most cases, the simplified condition we found is the best
1488 choice, but this is not the case for the min/max/abs transforms.
1489 For these we wish to know that it is A or B in the condition. */
1492 noce_get_alt_condition (struct noce_if_info *if_info, rtx target,
1495 rtx cond, set, insn;
1498 /* If target is already mentioned in the known condition, return it. */
1499 if (reg_mentioned_p (target, if_info->cond))
1501 *earliest = if_info->cond_earliest;
1502 return if_info->cond;
1505 set = pc_set (if_info->jump);
1506 cond = XEXP (SET_SRC (set), 0);
1508 = GET_CODE (XEXP (SET_SRC (set), 2)) == LABEL_REF
1509 && XEXP (XEXP (SET_SRC (set), 2), 0) == JUMP_LABEL (if_info->jump);
1510 if (if_info->then_else_reversed)
1513 /* If we're looking for a constant, try to make the conditional
1514 have that constant in it. There are two reasons why it may
1515 not have the constant we want:
1517 1. GCC may have needed to put the constant in a register, because
1518 the target can't compare directly against that constant. For
1519 this case, we look for a SET immediately before the comparison
1520 that puts a constant in that register.
1522 2. GCC may have canonicalized the conditional, for example
1523 replacing "if x < 4" with "if x <= 3". We can undo that (or
1524 make equivalent types of changes) to get the constants we need
1525 if they're off by one in the right direction. */
1527 if (GET_CODE (target) == CONST_INT)
1529 enum rtx_code code = GET_CODE (if_info->cond);
1530 rtx op_a = XEXP (if_info->cond, 0);
1531 rtx op_b = XEXP (if_info->cond, 1);
1534 /* First, look to see if we put a constant in a register. */
1535 prev_insn = prev_nonnote_insn (if_info->cond_earliest);
1537 && INSN_P (prev_insn)
1538 && GET_CODE (PATTERN (prev_insn)) == SET)
1540 rtx src = find_reg_equal_equiv_note (prev_insn);
1542 src = SET_SRC (PATTERN (prev_insn));
1543 if (GET_CODE (src) == CONST_INT)
1545 if (rtx_equal_p (op_a, SET_DEST (PATTERN (prev_insn))))
1547 else if (rtx_equal_p (op_b, SET_DEST (PATTERN (prev_insn))))
1550 if (GET_CODE (op_a) == CONST_INT)
1555 code = swap_condition (code);
1560 /* Now, look to see if we can get the right constant by
1561 adjusting the conditional. */
1562 if (GET_CODE (op_b) == CONST_INT)
1564 HOST_WIDE_INT desired_val = INTVAL (target);
1565 HOST_WIDE_INT actual_val = INTVAL (op_b);
1570 if (actual_val == desired_val + 1)
1573 op_b = GEN_INT (desired_val);
1577 if (actual_val == desired_val - 1)
1580 op_b = GEN_INT (desired_val);
1584 if (actual_val == desired_val - 1)
1587 op_b = GEN_INT (desired_val);
1591 if (actual_val == desired_val + 1)
1594 op_b = GEN_INT (desired_val);
1602 /* If we made any changes, generate a new conditional that is
1603 equivalent to what we started with, but has the right
1605 if (code != GET_CODE (if_info->cond)
1606 || op_a != XEXP (if_info->cond, 0)
1607 || op_b != XEXP (if_info->cond, 1))
1609 cond = gen_rtx_fmt_ee (code, GET_MODE (cond), op_a, op_b);
1610 *earliest = if_info->cond_earliest;
1615 cond = canonicalize_condition (if_info->jump, cond, reverse,
1616 earliest, target, false, true);
1617 if (! cond || ! reg_mentioned_p (target, cond))
1620 /* We almost certainly searched back to a different place.
1621 Need to re-verify correct lifetimes. */
1623 /* X may not be mentioned in the range (cond_earliest, jump]. */
1624 for (insn = if_info->jump; insn != *earliest; insn = PREV_INSN (insn))
1625 if (INSN_P (insn) && reg_overlap_mentioned_p (if_info->x, PATTERN (insn)))
1628 /* A and B may not be modified in the range [cond_earliest, jump). */
1629 for (insn = *earliest; insn != if_info->jump; insn = NEXT_INSN (insn))
1631 && (modified_in_p (if_info->a, insn)
1632 || modified_in_p (if_info->b, insn)))
1638 /* Convert "if (a < b) x = a; else x = b;" to "x = min(a, b);", etc. */
1641 noce_try_minmax (struct noce_if_info *if_info)
1643 rtx cond, earliest, target, seq;
1644 enum rtx_code code, op;
1647 /* ??? Reject modes with NaNs or signed zeros since we don't know how
1648 they will be resolved with an SMIN/SMAX. It wouldn't be too hard
1649 to get the target to tell us... */
1650 if (HONOR_SIGNED_ZEROS (GET_MODE (if_info->x))
1651 || HONOR_NANS (GET_MODE (if_info->x)))
1654 cond = noce_get_alt_condition (if_info, if_info->a, &earliest);
1658 /* Verify the condition is of the form we expect, and canonicalize
1659 the comparison code. */
1660 code = GET_CODE (cond);
1661 if (rtx_equal_p (XEXP (cond, 0), if_info->a))
1663 if (! rtx_equal_p (XEXP (cond, 1), if_info->b))
1666 else if (rtx_equal_p (XEXP (cond, 1), if_info->a))
1668 if (! rtx_equal_p (XEXP (cond, 0), if_info->b))
1670 code = swap_condition (code);
1675 /* Determine what sort of operation this is. Note that the code is for
1676 a taken branch, so the code->operation mapping appears backwards. */
1709 target = expand_simple_binop (GET_MODE (if_info->x), op,
1710 if_info->a, if_info->b,
1711 if_info->x, unsignedp, OPTAB_WIDEN);
1717 if (target != if_info->x)
1718 noce_emit_move_insn (if_info->x, target);
1720 seq = end_ifcvt_sequence (if_info);
1724 emit_insn_before_setloc (seq, if_info->jump, INSN_LOCATOR (if_info->insn_a));
1725 if_info->cond = cond;
1726 if_info->cond_earliest = earliest;
1731 /* Convert "if (a < 0) x = -a; else x = a;" to "x = abs(a);", etc. */
1734 noce_try_abs (struct noce_if_info *if_info)
1736 rtx cond, earliest, target, seq, a, b, c;
1739 /* Recognize A and B as constituting an ABS or NABS. The canonical
1740 form is a branch around the negation, taken when the object is the
1741 first operand of a comparison against 0 that evaluates to true. */
1744 if (GET_CODE (a) == NEG && rtx_equal_p (XEXP (a, 0), b))
1746 else if (GET_CODE (b) == NEG && rtx_equal_p (XEXP (b, 0), a))
1748 c = a; a = b; b = c;
1754 cond = noce_get_alt_condition (if_info, b, &earliest);
1758 /* Verify the condition is of the form we expect. */
1759 if (rtx_equal_p (XEXP (cond, 0), b))
1761 else if (rtx_equal_p (XEXP (cond, 1), b))
1769 /* Verify that C is zero. Search one step backward for a
1770 REG_EQUAL note or a simple source if necessary. */
1773 rtx set, insn = prev_nonnote_insn (earliest);
1775 && (set = single_set (insn))
1776 && rtx_equal_p (SET_DEST (set), c))
1778 rtx note = find_reg_equal_equiv_note (insn);
1788 && GET_CODE (XEXP (c, 0)) == SYMBOL_REF
1789 && CONSTANT_POOL_ADDRESS_P (XEXP (c, 0)))
1790 c = get_pool_constant (XEXP (c, 0));
1792 /* Work around funny ideas get_condition has wrt canonicalization.
1793 Note that these rtx constants are known to be CONST_INT, and
1794 therefore imply integer comparisons. */
1795 if (c == constm1_rtx && GET_CODE (cond) == GT)
1797 else if (c == const1_rtx && GET_CODE (cond) == LT)
1799 else if (c != CONST0_RTX (GET_MODE (b)))
1802 /* Determine what sort of operation this is. */
1803 switch (GET_CODE (cond))
1822 target = expand_abs_nojump (GET_MODE (if_info->x), b, if_info->x, 1);
1824 /* ??? It's a quandary whether cmove would be better here, especially
1825 for integers. Perhaps combine will clean things up. */
1826 if (target && negate)
1827 target = expand_simple_unop (GET_MODE (target), NEG, target, if_info->x, 0);
1835 if (target != if_info->x)
1836 noce_emit_move_insn (if_info->x, target);
1838 seq = end_ifcvt_sequence (if_info);
1842 emit_insn_before_setloc (seq, if_info->jump, INSN_LOCATOR (if_info->insn_a));
1843 if_info->cond = cond;
1844 if_info->cond_earliest = earliest;
1849 /* Convert "if (m < 0) x = b; else x = 0;" to "x = (m >> C) & b;". */
1852 noce_try_sign_mask (struct noce_if_info *if_info)
1854 rtx cond, t, m, c, seq;
1855 enum machine_mode mode;
1857 bool b_unconditional;
1859 cond = if_info->cond;
1860 code = GET_CODE (cond);
1865 if (if_info->a == const0_rtx)
1867 if ((code == LT && c == const0_rtx)
1868 || (code == LE && c == constm1_rtx))
1871 else if (if_info->b == const0_rtx)
1873 if ((code == GE && c == const0_rtx)
1874 || (code == GT && c == constm1_rtx))
1878 if (! t || side_effects_p (t))
1881 /* We currently don't handle different modes. */
1882 mode = GET_MODE (t);
1883 if (GET_MODE (m) != mode)
1886 /* This is only profitable if T is cheap, or T is unconditionally
1887 executed/evaluated in the original insn sequence. The latter
1888 happens if INSN_B was taken from TEST_BB, or if there was no
1889 INSN_B which can happen for e.g. conditional stores to memory. */
1890 b_unconditional = (if_info->insn_b == NULL_RTX
1891 || BLOCK_FOR_INSN (if_info->insn_b) == if_info->test_bb);
1892 if (rtx_cost (t, SET) >= COSTS_N_INSNS (2)
1893 && (!b_unconditional
1894 || t != if_info->b))
1898 /* Use emit_store_flag to generate "m < 0 ? -1 : 0" instead of expanding
1899 "(signed) m >> 31" directly. This benefits targets with specialized
1900 insns to obtain the signmask, but still uses ashr_optab otherwise. */
1901 m = emit_store_flag (gen_reg_rtx (mode), LT, m, const0_rtx, mode, 0, -1);
1902 t = m ? expand_binop (mode, and_optab, m, t, NULL_RTX, 0, OPTAB_DIRECT)
1911 noce_emit_move_insn (if_info->x, t);
1913 seq = end_ifcvt_sequence (if_info);
1917 emit_insn_before_setloc (seq, if_info->jump, INSN_LOCATOR (if_info->insn_a));
1922 /* Optimize away "if (x & C) x |= C" and similar bit manipulation
1926 noce_try_bitop (struct noce_if_info *if_info)
1928 rtx cond, x, a, result, seq;
1929 enum machine_mode mode;
1934 cond = if_info->cond;
1935 code = GET_CODE (cond);
1937 /* Check for no else condition. */
1938 if (! rtx_equal_p (x, if_info->b))
1941 /* Check for a suitable condition. */
1942 if (code != NE && code != EQ)
1944 if (XEXP (cond, 1) != const0_rtx)
1946 cond = XEXP (cond, 0);
1948 /* ??? We could also handle AND here. */
1949 if (GET_CODE (cond) == ZERO_EXTRACT)
1951 if (XEXP (cond, 1) != const1_rtx
1952 || GET_CODE (XEXP (cond, 2)) != CONST_INT
1953 || ! rtx_equal_p (x, XEXP (cond, 0)))
1955 bitnum = INTVAL (XEXP (cond, 2));
1956 mode = GET_MODE (x);
1957 if (BITS_BIG_ENDIAN)
1958 bitnum = GET_MODE_BITSIZE (mode) - 1 - bitnum;
1959 if (bitnum < 0 || bitnum >= HOST_BITS_PER_WIDE_INT)
1966 if (GET_CODE (a) == IOR || GET_CODE (a) == XOR)
1968 /* Check for "if (X & C) x = x op C". */
1969 if (! rtx_equal_p (x, XEXP (a, 0))
1970 || GET_CODE (XEXP (a, 1)) != CONST_INT
1971 || (INTVAL (XEXP (a, 1)) & GET_MODE_MASK (mode))
1972 != (unsigned HOST_WIDE_INT) 1 << bitnum)
1975 /* if ((x & C) == 0) x |= C; is transformed to x |= C. */
1976 /* if ((x & C) != 0) x |= C; is transformed to nothing. */
1977 if (GET_CODE (a) == IOR)
1978 result = (code == NE) ? a : NULL_RTX;
1979 else if (code == NE)
1981 /* if ((x & C) == 0) x ^= C; is transformed to x |= C. */
1982 result = gen_int_mode ((HOST_WIDE_INT) 1 << bitnum, mode);
1983 result = simplify_gen_binary (IOR, mode, x, result);
1987 /* if ((x & C) != 0) x ^= C; is transformed to x &= ~C. */
1988 result = gen_int_mode (~((HOST_WIDE_INT) 1 << bitnum), mode);
1989 result = simplify_gen_binary (AND, mode, x, result);
1992 else if (GET_CODE (a) == AND)
1994 /* Check for "if (X & C) x &= ~C". */
1995 if (! rtx_equal_p (x, XEXP (a, 0))
1996 || GET_CODE (XEXP (a, 1)) != CONST_INT
1997 || (INTVAL (XEXP (a, 1)) & GET_MODE_MASK (mode))
1998 != (~((HOST_WIDE_INT) 1 << bitnum) & GET_MODE_MASK (mode)))
2001 /* if ((x & C) == 0) x &= ~C; is transformed to nothing. */
2002 /* if ((x & C) != 0) x &= ~C; is transformed to x &= ~C. */
2003 result = (code == EQ) ? a : NULL_RTX;
2011 noce_emit_move_insn (x, result);
2012 seq = end_ifcvt_sequence (if_info);
2016 emit_insn_before_setloc (seq, if_info->jump,
2017 INSN_LOCATOR (if_info->insn_a));
2023 /* Similar to get_condition, only the resulting condition must be
2024 valid at JUMP, instead of at EARLIEST.
2026 If THEN_ELSE_REVERSED is true, the fallthrough does not go to the
2027 THEN block of the caller, and we have to reverse the condition. */
2030 noce_get_condition (rtx jump, rtx *earliest, bool then_else_reversed)
2035 if (! any_condjump_p (jump))
2038 set = pc_set (jump);
2040 /* If this branches to JUMP_LABEL when the condition is false,
2041 reverse the condition. */
2042 reverse = (GET_CODE (XEXP (SET_SRC (set), 2)) == LABEL_REF
2043 && XEXP (XEXP (SET_SRC (set), 2), 0) == JUMP_LABEL (jump));
2045 /* We may have to reverse because the caller's if block is not canonical,
2046 i.e. the THEN block isn't the fallthrough block for the TEST block
2047 (see find_if_header). */
2048 if (then_else_reversed)
2051 /* If the condition variable is a register and is MODE_INT, accept it. */
2053 cond = XEXP (SET_SRC (set), 0);
2054 tmp = XEXP (cond, 0);
2055 if (REG_P (tmp) && GET_MODE_CLASS (GET_MODE (tmp)) == MODE_INT)
2060 cond = gen_rtx_fmt_ee (reverse_condition (GET_CODE (cond)),
2061 GET_MODE (cond), tmp, XEXP (cond, 1));
2065 /* Otherwise, fall back on canonicalize_condition to do the dirty
2066 work of manipulating MODE_CC values and COMPARE rtx codes. */
2067 return canonicalize_condition (jump, cond, reverse, earliest,
2068 NULL_RTX, false, true);
2071 /* Return true if OP is ok for if-then-else processing. */
2074 noce_operand_ok (const_rtx op)
2076 /* We special-case memories, so handle any of them with
2077 no address side effects. */
2079 return ! side_effects_p (XEXP (op, 0));
2081 if (side_effects_p (op))
2084 return ! may_trap_p (op);
2087 /* Return true if a write into MEM may trap or fault. */
2090 noce_mem_write_may_trap_or_fault_p (const_rtx mem)
2094 if (MEM_READONLY_P (mem))
2097 if (may_trap_or_fault_p (mem))
2100 addr = XEXP (mem, 0);
2102 /* Call target hook to avoid the effects of -fpic etc.... */
2103 addr = targetm.delegitimize_address (addr);
2106 switch (GET_CODE (addr))
2114 addr = XEXP (addr, 0);
2118 addr = XEXP (addr, 1);
2121 if (GET_CODE (XEXP (addr, 1)) == CONST_INT)
2122 addr = XEXP (addr, 0);
2129 if (SYMBOL_REF_DECL (addr)
2130 && decl_readonly_section (SYMBOL_REF_DECL (addr), 0))
2140 /* Given a simple IF-THEN-JOIN or IF-THEN-ELSE-JOIN block, attempt to convert
2141 it without using conditional execution. Return TRUE if we were successful
2142 at converting the block. */
2145 noce_process_if_block (struct noce_if_info *if_info)
2147 basic_block test_bb = if_info->test_bb; /* test block */
2148 basic_block then_bb = if_info->then_bb; /* THEN */
2149 basic_block else_bb = if_info->else_bb; /* ELSE or NULL */
2150 basic_block join_bb = if_info->join_bb; /* JOIN */
2151 rtx jump = if_info->jump;
2152 rtx cond = if_info->cond;
2155 rtx orig_x, x, a, b;
2157 /* We're looking for patterns of the form
2159 (1) if (...) x = a; else x = b;
2160 (2) x = b; if (...) x = a;
2161 (3) if (...) x = a; // as if with an initial x = x.
2163 The later patterns require jumps to be more expensive.
2165 ??? For future expansion, look for multiple X in such patterns. */
2167 /* Look for one of the potential sets. */
2168 insn_a = first_active_insn (then_bb);
2170 || insn_a != last_active_insn (then_bb, FALSE)
2171 || (set_a = single_set (insn_a)) == NULL_RTX)
2174 x = SET_DEST (set_a);
2175 a = SET_SRC (set_a);
2177 /* Look for the other potential set. Make sure we've got equivalent
2179 /* ??? This is overconservative. Storing to two different mems is
2180 as easy as conditionally computing the address. Storing to a
2181 single mem merely requires a scratch memory to use as one of the
2182 destination addresses; often the memory immediately below the
2183 stack pointer is available for this. */
2187 insn_b = first_active_insn (else_bb);
2189 || insn_b != last_active_insn (else_bb, FALSE)
2190 || (set_b = single_set (insn_b)) == NULL_RTX
2191 || ! rtx_equal_p (x, SET_DEST (set_b)))
2196 insn_b = prev_nonnote_insn (if_info->cond_earliest);
2197 /* We're going to be moving the evaluation of B down from above
2198 COND_EARLIEST to JUMP. Make sure the relevant data is still
2201 || !NONJUMP_INSN_P (insn_b)
2202 || (set_b = single_set (insn_b)) == NULL_RTX
2203 || ! rtx_equal_p (x, SET_DEST (set_b))
2204 || reg_overlap_mentioned_p (x, SET_SRC (set_b))
2205 || modified_between_p (SET_SRC (set_b),
2206 PREV_INSN (if_info->cond_earliest), jump)
2207 /* Likewise with X. In particular this can happen when
2208 noce_get_condition looks farther back in the instruction
2209 stream than one might expect. */
2210 || reg_overlap_mentioned_p (x, cond)
2211 || reg_overlap_mentioned_p (x, a)
2212 || modified_between_p (x, PREV_INSN (if_info->cond_earliest), jump))
2213 insn_b = set_b = NULL_RTX;
2216 /* If x has side effects then only the if-then-else form is safe to
2217 convert. But even in that case we would need to restore any notes
2218 (such as REG_INC) at then end. That can be tricky if
2219 noce_emit_move_insn expands to more than one insn, so disable the
2220 optimization entirely for now if there are side effects. */
2221 if (side_effects_p (x))
2224 b = (set_b ? SET_SRC (set_b) : x);
2226 /* Only operate on register destinations, and even then avoid extending
2227 the lifetime of hard registers on small register class machines. */
2230 || (SMALL_REGISTER_CLASSES
2231 && REGNO (x) < FIRST_PSEUDO_REGISTER))
2233 if (GET_MODE (x) == BLKmode)
2236 if (GET_MODE (x) == ZERO_EXTRACT
2237 && (GET_CODE (XEXP (x, 1)) != CONST_INT
2238 || GET_CODE (XEXP (x, 2)) != CONST_INT))
2241 x = gen_reg_rtx (GET_MODE (GET_CODE (x) == STRICT_LOW_PART
2242 ? XEXP (x, 0) : x));
2245 /* Don't operate on sources that may trap or are volatile. */
2246 if (! noce_operand_ok (a) || ! noce_operand_ok (b))
2249 /* Set up the info block for our subroutines. */
2250 if_info->insn_a = insn_a;
2251 if_info->insn_b = insn_b;
2256 /* Try optimizations in some approximation of a useful order. */
2257 /* ??? Should first look to see if X is live incoming at all. If it
2258 isn't, we don't need anything but an unconditional set. */
2260 /* Look and see if A and B are really the same. Avoid creating silly
2261 cmove constructs that no one will fix up later. */
2262 if (rtx_equal_p (a, b))
2264 /* If we have an INSN_B, we don't have to create any new rtl. Just
2265 move the instruction that we already have. If we don't have an
2266 INSN_B, that means that A == X, and we've got a noop move. In
2267 that case don't do anything and let the code below delete INSN_A. */
2268 if (insn_b && else_bb)
2272 if (else_bb && insn_b == BB_END (else_bb))
2273 BB_END (else_bb) = PREV_INSN (insn_b);
2274 reorder_insns (insn_b, insn_b, PREV_INSN (jump));
2276 /* If there was a REG_EQUAL note, delete it since it may have been
2277 true due to this insn being after a jump. */
2278 if ((note = find_reg_note (insn_b, REG_EQUAL, NULL_RTX)) != 0)
2279 remove_note (insn_b, note);
2283 /* If we have "x = b; if (...) x = a;", and x has side-effects, then
2284 x must be executed twice. */
2285 else if (insn_b && side_effects_p (orig_x))
2292 /* Disallow the "if (...) x = a;" form (with an implicit "else x = x;")
2293 for optimizations if writing to x may trap or fault, i.e. it's a memory
2294 other than a static var or a stack slot, is misaligned on strict
2295 aligned machines or is read-only.
2296 If x is a read-only memory, then the program is valid only if we
2297 avoid the store into it. If there are stores on both the THEN and
2298 ELSE arms, then we can go ahead with the conversion; either the
2299 program is broken, or the condition is always false such that the
2300 other memory is selected. */
2301 if (!set_b && MEM_P (orig_x) && noce_mem_write_may_trap_or_fault_p (orig_x))
2304 if (noce_try_move (if_info))
2306 if (noce_try_store_flag (if_info))
2308 if (noce_try_bitop (if_info))
2310 if (noce_try_minmax (if_info))
2312 if (noce_try_abs (if_info))
2314 if (HAVE_conditional_move
2315 && noce_try_cmove (if_info))
2317 if (! HAVE_conditional_execution)
2319 if (noce_try_store_flag_constants (if_info))
2321 if (noce_try_addcc (if_info))
2323 if (noce_try_store_flag_mask (if_info))
2325 if (HAVE_conditional_move
2326 && noce_try_cmove_arith (if_info))
2328 if (noce_try_sign_mask (if_info))
2336 /* If we used a temporary, fix it up now. */
2342 noce_emit_move_insn (orig_x, x);
2344 set_used_flags (orig_x);
2345 unshare_all_rtl_in_chain (seq);
2348 emit_insn_before_setloc (seq, BB_END (test_bb), INSN_LOCATOR (insn_a));
2351 /* The original THEN and ELSE blocks may now be removed. The test block
2352 must now jump to the join block. If the test block and the join block
2353 can be merged, do so. */
2356 delete_basic_block (else_bb);
2360 remove_edge (find_edge (test_bb, join_bb));
2362 remove_edge (find_edge (then_bb, join_bb));
2363 redirect_edge_and_branch_force (single_succ_edge (test_bb), join_bb);
2364 delete_basic_block (then_bb);
2367 if (can_merge_blocks_p (test_bb, join_bb))
2369 merge_blocks (test_bb, join_bb);
2373 num_updated_if_blocks++;
2377 /* Check whether a block is suitable for conditional move conversion.
2378 Every insn must be a simple set of a register to a constant or a
2379 register. For each assignment, store the value in the array VALS,
2380 indexed by register number, then store the register number in
2381 REGS. COND is the condition we will test. */
2384 check_cond_move_block (basic_block bb, rtx *vals, VEC (int, heap) *regs, rtx cond)
2388 /* We can only handle simple jumps at the end of the basic block.
2389 It is almost impossible to update the CFG otherwise. */
2391 if (JUMP_P (insn) && !onlyjump_p (insn))
2394 FOR_BB_INSNS (bb, insn)
2398 if (!INSN_P (insn) || JUMP_P (insn))
2400 set = single_set (insn);
2404 dest = SET_DEST (set);
2405 src = SET_SRC (set);
2407 || (SMALL_REGISTER_CLASSES && HARD_REGISTER_P (dest)))
2410 if (!CONSTANT_P (src) && !register_operand (src, VOIDmode))
2413 if (side_effects_p (src) || side_effects_p (dest))
2416 if (may_trap_p (src) || may_trap_p (dest))
2419 /* Don't try to handle this if the source register was
2420 modified earlier in the block. */
2422 && vals[REGNO (src)] != NULL)
2423 || (GET_CODE (src) == SUBREG && REG_P (SUBREG_REG (src))
2424 && vals[REGNO (SUBREG_REG (src))] != NULL))
2427 /* Don't try to handle this if the destination register was
2428 modified earlier in the block. */
2429 if (vals[REGNO (dest)] != NULL)
2432 /* Don't try to handle this if the condition uses the
2433 destination register. */
2434 if (reg_overlap_mentioned_p (dest, cond))
2437 /* Don't try to handle this if the source register is modified
2438 later in the block. */
2439 if (!CONSTANT_P (src)
2440 && modified_between_p (src, insn, NEXT_INSN (BB_END (bb))))
2443 vals[REGNO (dest)] = src;
2445 VEC_safe_push (int, heap, regs, REGNO (dest));
2451 /* Given a basic block BB suitable for conditional move conversion,
2452 a condition COND, and arrays THEN_VALS and ELSE_VALS containing the
2453 register values depending on COND, emit the insns in the block as
2454 conditional moves. If ELSE_BLOCK is true, THEN_BB was already
2455 processed. The caller has started a sequence for the conversion.
2456 Return true if successful, false if something goes wrong. */
2459 cond_move_convert_if_block (struct noce_if_info *if_infop,
2460 basic_block bb, rtx cond,
2461 rtx *then_vals, rtx *else_vals,
2465 rtx insn, cond_arg0, cond_arg1;
2467 code = GET_CODE (cond);
2468 cond_arg0 = XEXP (cond, 0);
2469 cond_arg1 = XEXP (cond, 1);
2471 FOR_BB_INSNS (bb, insn)
2473 rtx set, target, dest, t, e;
2476 if (!INSN_P (insn) || JUMP_P (insn))
2478 set = single_set (insn);
2479 gcc_assert (set && REG_P (SET_DEST (set)));
2481 dest = SET_DEST (set);
2482 regno = REGNO (dest);
2484 t = then_vals[regno];
2485 e = else_vals[regno];
2489 /* If this register was set in the then block, we already
2490 handled this case there. */
2503 target = noce_emit_cmove (if_infop, dest, code, cond_arg0, cond_arg1,
2509 noce_emit_move_insn (dest, target);
2515 /* Given a simple IF-THEN-JOIN or IF-THEN-ELSE-JOIN block, attempt to convert
2516 it using only conditional moves. Return TRUE if we were successful at
2517 converting the block. */
2520 cond_move_process_if_block (struct noce_if_info *if_info)
2522 basic_block test_bb = if_info->test_bb;
2523 basic_block then_bb = if_info->then_bb;
2524 basic_block else_bb = if_info->else_bb;
2525 basic_block join_bb = if_info->join_bb;
2526 rtx jump = if_info->jump;
2527 rtx cond = if_info->cond;
2529 int max_reg, size, c, reg;
2532 VEC (int, heap) *then_regs = NULL;
2533 VEC (int, heap) *else_regs = NULL;
2536 /* Build a mapping for each block to the value used for each
2538 max_reg = max_reg_num ();
2539 size = (max_reg + 1) * sizeof (rtx);
2540 then_vals = (rtx *) alloca (size);
2541 else_vals = (rtx *) alloca (size);
2542 memset (then_vals, 0, size);
2543 memset (else_vals, 0, size);
2545 /* Make sure the blocks are suitable. */
2546 if (!check_cond_move_block (then_bb, then_vals, then_regs, cond)
2547 || (else_bb && !check_cond_move_block (else_bb, else_vals, else_regs, cond)))
2550 /* Make sure the blocks can be used together. If the same register
2551 is set in both blocks, and is not set to a constant in both
2552 cases, then both blocks must set it to the same register. We
2553 have already verified that if it is set to a register, that the
2554 source register does not change after the assignment. Also count
2555 the number of registers set in only one of the blocks. */
2557 for (i = 0; VEC_iterate (int, then_regs, i, reg); i++)
2559 if (!then_vals[reg] && !else_vals[reg])
2562 if (!else_vals[reg])
2566 if (!CONSTANT_P (then_vals[reg])
2567 && !CONSTANT_P (else_vals[reg])
2568 && !rtx_equal_p (then_vals[reg], else_vals[reg]))
2573 /* Finish off c for MAX_CONDITIONAL_EXECUTE. */
2574 for (i = 0; VEC_iterate (int, else_regs, i, reg); ++i)
2575 if (!then_vals[reg])
2578 /* Make sure it is reasonable to convert this block. What matters
2579 is the number of assignments currently made in only one of the
2580 branches, since if we convert we are going to always execute
2582 if (c > MAX_CONDITIONAL_EXECUTE)
2585 /* Try to emit the conditional moves. First do the then block,
2586 then do anything left in the else blocks. */
2588 if (!cond_move_convert_if_block (if_info, then_bb, cond,
2589 then_vals, else_vals, false)
2591 && !cond_move_convert_if_block (if_info, else_bb, cond,
2592 then_vals, else_vals, true)))
2597 seq = end_ifcvt_sequence (if_info);
2601 loc_insn = first_active_insn (then_bb);
2604 loc_insn = first_active_insn (else_bb);
2605 gcc_assert (loc_insn);
2607 emit_insn_before_setloc (seq, jump, INSN_LOCATOR (loc_insn));
2611 delete_basic_block (else_bb);
2615 remove_edge (find_edge (test_bb, join_bb));
2617 remove_edge (find_edge (then_bb, join_bb));
2618 redirect_edge_and_branch_force (single_succ_edge (test_bb), join_bb);
2619 delete_basic_block (then_bb);
2622 if (can_merge_blocks_p (test_bb, join_bb))
2624 merge_blocks (test_bb, join_bb);
2628 num_updated_if_blocks++;
2630 VEC_free (int, heap, then_regs);
2631 VEC_free (int, heap, else_regs);
2637 /* Determine if a given basic block heads a simple IF-THEN-JOIN or an
2638 IF-THEN-ELSE-JOIN block.
2640 If so, we'll try to convert the insns to not require the branch,
2641 using only transformations that do not require conditional execution.
2643 Return TRUE if we were successful at converting the block. */
2646 noce_find_if_block (basic_block test_bb,
2647 edge then_edge, edge else_edge,
2650 basic_block then_bb, else_bb, join_bb;
2651 bool then_else_reversed = false;
2654 struct noce_if_info if_info;
2656 /* We only ever should get here before reload. */
2657 gcc_assert (!reload_completed);
2659 /* Recognize an IF-THEN-ELSE-JOIN block. */
2660 if (single_pred_p (then_edge->dest)
2661 && single_succ_p (then_edge->dest)
2662 && single_pred_p (else_edge->dest)
2663 && single_succ_p (else_edge->dest)
2664 && single_succ (then_edge->dest) == single_succ (else_edge->dest))
2666 then_bb = then_edge->dest;
2667 else_bb = else_edge->dest;
2668 join_bb = single_succ (then_bb);
2670 /* Recognize an IF-THEN-JOIN block. */
2671 else if (single_pred_p (then_edge->dest)
2672 && single_succ_p (then_edge->dest)
2673 && single_succ (then_edge->dest) == else_edge->dest)
2675 then_bb = then_edge->dest;
2676 else_bb = NULL_BLOCK;
2677 join_bb = else_edge->dest;
2679 /* Recognize an IF-ELSE-JOIN block. We can have those because the order
2680 of basic blocks in cfglayout mode does not matter, so the fallthrough
2681 edge can go to any basic block (and not just to bb->next_bb, like in
2683 else if (single_pred_p (else_edge->dest)
2684 && single_succ_p (else_edge->dest)
2685 && single_succ (else_edge->dest) == then_edge->dest)
2687 /* The noce transformations do not apply to IF-ELSE-JOIN blocks.
2688 To make this work, we have to invert the THEN and ELSE blocks
2689 and reverse the jump condition. */
2690 then_bb = else_edge->dest;
2691 else_bb = NULL_BLOCK;
2692 join_bb = single_succ (then_bb);
2693 then_else_reversed = true;
2696 /* Not a form we can handle. */
2699 /* The edges of the THEN and ELSE blocks cannot have complex edges. */
2700 if (single_succ_edge (then_bb)->flags & EDGE_COMPLEX)
2703 && single_succ_edge (else_bb)->flags & EDGE_COMPLEX)
2706 num_possible_if_blocks++;
2711 "\nIF-THEN%s-JOIN block found, pass %d, test %d, then %d",
2712 (else_bb) ? "-ELSE" : "",
2713 pass, test_bb->index, then_bb->index);
2716 fprintf (dump_file, ", else %d", else_bb->index);
2718 fprintf (dump_file, ", join %d\n", join_bb->index);
2721 /* If the conditional jump is more than just a conditional
2722 jump, then we can not do if-conversion on this block. */
2723 jump = BB_END (test_bb);
2724 if (! onlyjump_p (jump))
2727 /* If this is not a standard conditional jump, we can't parse it. */
2728 cond = noce_get_condition (jump,
2730 then_else_reversed);
2734 /* We must be comparing objects whose modes imply the size. */
2735 if (GET_MODE (XEXP (cond, 0)) == BLKmode)
2738 /* Initialize an IF_INFO struct to pass around. */
2739 memset (&if_info, 0, sizeof if_info);
2740 if_info.test_bb = test_bb;
2741 if_info.then_bb = then_bb;
2742 if_info.else_bb = else_bb;
2743 if_info.join_bb = join_bb;
2744 if_info.cond = cond;
2745 if_info.cond_earliest = cond_earliest;
2746 if_info.jump = jump;
2747 if_info.then_else_reversed = then_else_reversed;
2749 /* Do the real work. */
2751 if (noce_process_if_block (&if_info))
2754 if (HAVE_conditional_move
2755 && cond_move_process_if_block (&if_info))
2762 /* Merge the blocks and mark for local life update. */
2765 merge_if_block (struct ce_if_block * ce_info)
2767 basic_block test_bb = ce_info->test_bb; /* last test block */
2768 basic_block then_bb = ce_info->then_bb; /* THEN */
2769 basic_block else_bb = ce_info->else_bb; /* ELSE or NULL */
2770 basic_block join_bb = ce_info->join_bb; /* join block */
2771 basic_block combo_bb;
2773 /* All block merging is done into the lower block numbers. */
2776 df_set_bb_dirty (test_bb);
2778 /* Merge any basic blocks to handle && and || subtests. Each of
2779 the blocks are on the fallthru path from the predecessor block. */
2780 if (ce_info->num_multiple_test_blocks > 0)
2782 basic_block bb = test_bb;
2783 basic_block last_test_bb = ce_info->last_test_bb;
2784 basic_block fallthru = block_fallthru (bb);
2789 fallthru = block_fallthru (bb);
2790 merge_blocks (combo_bb, bb);
2793 while (bb != last_test_bb);
2796 /* Merge TEST block into THEN block. Normally the THEN block won't have a
2797 label, but it might if there were || tests. That label's count should be
2798 zero, and it normally should be removed. */
2802 merge_blocks (combo_bb, then_bb);
2806 /* The ELSE block, if it existed, had a label. That label count
2807 will almost always be zero, but odd things can happen when labels
2808 get their addresses taken. */
2811 merge_blocks (combo_bb, else_bb);
2815 /* If there was no join block reported, that means it was not adjacent
2816 to the others, and so we cannot merge them. */
2820 rtx last = BB_END (combo_bb);
2822 /* The outgoing edge for the current COMBO block should already
2823 be correct. Verify this. */
2824 if (EDGE_COUNT (combo_bb->succs) == 0)
2825 gcc_assert (find_reg_note (last, REG_NORETURN, NULL)
2826 || (NONJUMP_INSN_P (last)
2827 && GET_CODE (PATTERN (last)) == TRAP_IF
2828 && (TRAP_CONDITION (PATTERN (last))
2829 == const_true_rtx)));
2832 /* There should still be something at the end of the THEN or ELSE
2833 blocks taking us to our final destination. */
2834 gcc_assert (JUMP_P (last)
2835 || (EDGE_SUCC (combo_bb, 0)->dest == EXIT_BLOCK_PTR
2837 && SIBLING_CALL_P (last))
2838 || ((EDGE_SUCC (combo_bb, 0)->flags & EDGE_EH)
2839 && can_throw_internal (last)));
2842 /* The JOIN block may have had quite a number of other predecessors too.
2843 Since we've already merged the TEST, THEN and ELSE blocks, we should
2844 have only one remaining edge from our if-then-else diamond. If there
2845 is more than one remaining edge, it must come from elsewhere. There
2846 may be zero incoming edges if the THEN block didn't actually join
2847 back up (as with a call to a non-return function). */
2848 else if (EDGE_COUNT (join_bb->preds) < 2
2849 && join_bb != EXIT_BLOCK_PTR)
2851 /* We can merge the JOIN cleanly and update the dataflow try
2852 again on this pass.*/
2853 merge_blocks (combo_bb, join_bb);
2858 /* We cannot merge the JOIN. */
2860 /* The outgoing edge for the current COMBO block should already
2861 be correct. Verify this. */
2862 gcc_assert (single_succ_p (combo_bb)
2863 && single_succ (combo_bb) == join_bb);
2865 /* Remove the jump and cruft from the end of the COMBO block. */
2866 if (join_bb != EXIT_BLOCK_PTR)
2867 tidy_fallthru_edge (single_succ_edge (combo_bb));
2870 num_updated_if_blocks++;
2873 /* Find a block ending in a simple IF condition and try to transform it
2874 in some way. When converting a multi-block condition, put the new code
2875 in the first such block and delete the rest. Return a pointer to this
2876 first block if some transformation was done. Return NULL otherwise. */
2879 find_if_header (basic_block test_bb, int pass)
2881 ce_if_block_t ce_info;
2885 /* The kind of block we're looking for has exactly two successors. */
2886 if (EDGE_COUNT (test_bb->succs) != 2)
2889 then_edge = EDGE_SUCC (test_bb, 0);
2890 else_edge = EDGE_SUCC (test_bb, 1);
2892 if (df_get_bb_dirty (then_edge->dest))
2894 if (df_get_bb_dirty (else_edge->dest))
2897 /* Neither edge should be abnormal. */
2898 if ((then_edge->flags & EDGE_COMPLEX)
2899 || (else_edge->flags & EDGE_COMPLEX))
2902 /* Nor exit the loop. */
2903 if ((then_edge->flags & EDGE_LOOP_EXIT)
2904 || (else_edge->flags & EDGE_LOOP_EXIT))
2907 /* The THEN edge is canonically the one that falls through. */
2908 if (then_edge->flags & EDGE_FALLTHRU)
2910 else if (else_edge->flags & EDGE_FALLTHRU)
2913 else_edge = then_edge;
2917 /* Otherwise this must be a multiway branch of some sort. */
2920 memset (&ce_info, '\0', sizeof (ce_info));
2921 ce_info.test_bb = test_bb;
2922 ce_info.then_bb = then_edge->dest;
2923 ce_info.else_bb = else_edge->dest;
2924 ce_info.pass = pass;
2926 #ifdef IFCVT_INIT_EXTRA_FIELDS
2927 IFCVT_INIT_EXTRA_FIELDS (&ce_info);
2930 if (! reload_completed
2931 && noce_find_if_block (test_bb, then_edge, else_edge, pass))
2934 if (HAVE_conditional_execution && reload_completed
2935 && cond_exec_find_if_block (&ce_info))
2938 if (HAVE_trap && HAVE_conditional_trap
2939 && find_cond_trap (test_bb, then_edge, else_edge))
2942 if (dom_info_state (CDI_POST_DOMINATORS) >= DOM_NO_FAST_QUERY
2943 && (! HAVE_conditional_execution || reload_completed))
2945 if (find_if_case_1 (test_bb, then_edge, else_edge))
2947 if (find_if_case_2 (test_bb, then_edge, else_edge))
2955 fprintf (dump_file, "Conversion succeeded on pass %d.\n", pass);
2956 /* Set this so we continue looking. */
2957 cond_exec_changed_p = TRUE;
2958 return ce_info.test_bb;
2961 /* Return true if a block has two edges, one of which falls through to the next
2962 block, and the other jumps to a specific block, so that we can tell if the
2963 block is part of an && test or an || test. Returns either -1 or the number
2964 of non-note, non-jump, non-USE/CLOBBER insns in the block. */
2967 block_jumps_and_fallthru_p (basic_block cur_bb, basic_block target_bb)
2970 int fallthru_p = FALSE;
2977 if (!cur_bb || !target_bb)
2980 /* If no edges, obviously it doesn't jump or fallthru. */
2981 if (EDGE_COUNT (cur_bb->succs) == 0)
2984 FOR_EACH_EDGE (cur_edge, ei, cur_bb->succs)
2986 if (cur_edge->flags & EDGE_COMPLEX)
2987 /* Anything complex isn't what we want. */
2990 else if (cur_edge->flags & EDGE_FALLTHRU)
2993 else if (cur_edge->dest == target_bb)
3000 if ((jump_p & fallthru_p) == 0)
3003 /* Don't allow calls in the block, since this is used to group && and ||
3004 together for conditional execution support. ??? we should support
3005 conditional execution support across calls for IA-64 some day, but
3006 for now it makes the code simpler. */
3007 end = BB_END (cur_bb);
3008 insn = BB_HEAD (cur_bb);
3010 while (insn != NULL_RTX)
3017 && GET_CODE (PATTERN (insn)) != USE
3018 && GET_CODE (PATTERN (insn)) != CLOBBER)
3024 insn = NEXT_INSN (insn);
3030 /* Determine if a given basic block heads a simple IF-THEN or IF-THEN-ELSE
3031 block. If so, we'll try to convert the insns to not require the branch.
3032 Return TRUE if we were successful at converting the block. */
3035 cond_exec_find_if_block (struct ce_if_block * ce_info)
3037 basic_block test_bb = ce_info->test_bb;
3038 basic_block then_bb = ce_info->then_bb;
3039 basic_block else_bb = ce_info->else_bb;
3040 basic_block join_bb = NULL_BLOCK;
3045 ce_info->last_test_bb = test_bb;
3047 /* We only ever should get here after reload,
3048 and only if we have conditional execution. */
3049 gcc_assert (HAVE_conditional_execution && reload_completed);
3051 /* Discover if any fall through predecessors of the current test basic block
3052 were && tests (which jump to the else block) or || tests (which jump to
3054 if (single_pred_p (test_bb)
3055 && single_pred_edge (test_bb)->flags == EDGE_FALLTHRU)
3057 basic_block bb = single_pred (test_bb);
3058 basic_block target_bb;
3059 int max_insns = MAX_CONDITIONAL_EXECUTE;
3062 /* Determine if the preceding block is an && or || block. */
3063 if ((n_insns = block_jumps_and_fallthru_p (bb, else_bb)) >= 0)
3065 ce_info->and_and_p = TRUE;
3066 target_bb = else_bb;
3068 else if ((n_insns = block_jumps_and_fallthru_p (bb, then_bb)) >= 0)
3070 ce_info->and_and_p = FALSE;
3071 target_bb = then_bb;
3074 target_bb = NULL_BLOCK;
3076 if (target_bb && n_insns <= max_insns)
3078 int total_insns = 0;
3081 ce_info->last_test_bb = test_bb;
3083 /* Found at least one && or || block, look for more. */
3086 ce_info->test_bb = test_bb = bb;
3087 total_insns += n_insns;
3090 if (!single_pred_p (bb))
3093 bb = single_pred (bb);
3094 n_insns = block_jumps_and_fallthru_p (bb, target_bb);
3096 while (n_insns >= 0 && (total_insns + n_insns) <= max_insns);
3098 ce_info->num_multiple_test_blocks = blocks;
3099 ce_info->num_multiple_test_insns = total_insns;
3101 if (ce_info->and_and_p)
3102 ce_info->num_and_and_blocks = blocks;
3104 ce_info->num_or_or_blocks = blocks;
3108 /* The THEN block of an IF-THEN combo must have exactly one predecessor,
3109 other than any || blocks which jump to the THEN block. */
3110 if ((EDGE_COUNT (then_bb->preds) - ce_info->num_or_or_blocks) != 1)
3113 /* The edges of the THEN and ELSE blocks cannot have complex edges. */
3114 FOR_EACH_EDGE (cur_edge, ei, then_bb->preds)
3116 if (cur_edge->flags & EDGE_COMPLEX)
3120 FOR_EACH_EDGE (cur_edge, ei, else_bb->preds)
3122 if (cur_edge->flags & EDGE_COMPLEX)
3126 /* The THEN block of an IF-THEN combo must have zero or one successors. */
3127 if (EDGE_COUNT (then_bb->succs) > 0
3128 && (!single_succ_p (then_bb)
3129 || (single_succ_edge (then_bb)->flags & EDGE_COMPLEX)
3130 || (epilogue_completed && tablejump_p (BB_END (then_bb), NULL, NULL))))
3133 /* If the THEN block has no successors, conditional execution can still
3134 make a conditional call. Don't do this unless the ELSE block has
3135 only one incoming edge -- the CFG manipulation is too ugly otherwise.
3136 Check for the last insn of the THEN block being an indirect jump, which
3137 is listed as not having any successors, but confuses the rest of the CE
3138 code processing. ??? we should fix this in the future. */
3139 if (EDGE_COUNT (then_bb->succs) == 0)
3141 if (single_pred_p (else_bb))
3143 rtx last_insn = BB_END (then_bb);
3146 && NOTE_P (last_insn)
3147 && last_insn != BB_HEAD (then_bb))
3148 last_insn = PREV_INSN (last_insn);
3151 && JUMP_P (last_insn)
3152 && ! simplejump_p (last_insn))
3156 else_bb = NULL_BLOCK;
3162 /* If the THEN block's successor is the other edge out of the TEST block,
3163 then we have an IF-THEN combo without an ELSE. */
3164 else if (single_succ (then_bb) == else_bb)
3167 else_bb = NULL_BLOCK;
3170 /* If the THEN and ELSE block meet in a subsequent block, and the ELSE
3171 has exactly one predecessor and one successor, and the outgoing edge
3172 is not complex, then we have an IF-THEN-ELSE combo. */
3173 else if (single_succ_p (else_bb)
3174 && single_succ (then_bb) == single_succ (else_bb)
3175 && single_pred_p (else_bb)
3176 && ! (single_succ_edge (else_bb)->flags & EDGE_COMPLEX)
3177 && ! (epilogue_completed && tablejump_p (BB_END (else_bb), NULL, NULL)))
3178 join_bb = single_succ (else_bb);
3180 /* Otherwise it is not an IF-THEN or IF-THEN-ELSE combination. */
3184 num_possible_if_blocks++;
3189 "\nIF-THEN%s block found, pass %d, start block %d "
3190 "[insn %d], then %d [%d]",
3191 (else_bb) ? "-ELSE" : "",
3194 BB_HEAD (test_bb) ? (int)INSN_UID (BB_HEAD (test_bb)) : -1,
3196 BB_HEAD (then_bb) ? (int)INSN_UID (BB_HEAD (then_bb)) : -1);
3199 fprintf (dump_file, ", else %d [%d]",
3201 BB_HEAD (else_bb) ? (int)INSN_UID (BB_HEAD (else_bb)) : -1);
3203 fprintf (dump_file, ", join %d [%d]",
3205 BB_HEAD (join_bb) ? (int)INSN_UID (BB_HEAD (join_bb)) : -1);
3207 if (ce_info->num_multiple_test_blocks > 0)
3208 fprintf (dump_file, ", %d %s block%s last test %d [%d]",
3209 ce_info->num_multiple_test_blocks,
3210 (ce_info->and_and_p) ? "&&" : "||",
3211 (ce_info->num_multiple_test_blocks == 1) ? "" : "s",
3212 ce_info->last_test_bb->index,
3213 ((BB_HEAD (ce_info->last_test_bb))
3214 ? (int)INSN_UID (BB_HEAD (ce_info->last_test_bb))
3217 fputc ('\n', dump_file);
3220 /* Make sure IF, THEN, and ELSE, blocks are adjacent. Actually, we get the
3221 first condition for free, since we've already asserted that there's a
3222 fallthru edge from IF to THEN. Likewise for the && and || blocks, since
3223 we checked the FALLTHRU flag, those are already adjacent to the last IF
3225 /* ??? As an enhancement, move the ELSE block. Have to deal with
3226 BLOCK notes, if by no other means than backing out the merge if they
3227 exist. Sticky enough I don't want to think about it now. */
3229 if (else_bb && (next = next->next_bb) != else_bb)
3231 if ((next = next->next_bb) != join_bb && join_bb != EXIT_BLOCK_PTR)
3239 /* Do the real work. */
3241 ce_info->else_bb = else_bb;
3242 ce_info->join_bb = join_bb;
3244 /* If we have && and || tests, try to first handle combining the && and ||
3245 tests into the conditional code, and if that fails, go back and handle
3246 it without the && and ||, which at present handles the && case if there
3247 was no ELSE block. */
3248 if (cond_exec_process_if_block (ce_info, TRUE))
3251 if (ce_info->num_multiple_test_blocks)
3255 if (cond_exec_process_if_block (ce_info, FALSE))
3262 /* Convert a branch over a trap, or a branch
3263 to a trap, into a conditional trap. */
3266 find_cond_trap (basic_block test_bb, edge then_edge, edge else_edge)
3268 basic_block then_bb = then_edge->dest;
3269 basic_block else_bb = else_edge->dest;
3270 basic_block other_bb, trap_bb;
3271 rtx trap, jump, cond, cond_earliest, seq;
3274 /* Locate the block with the trap instruction. */
3275 /* ??? While we look for no successors, we really ought to allow
3276 EH successors. Need to fix merge_if_block for that to work. */
3277 if ((trap = block_has_only_trap (then_bb)) != NULL)
3278 trap_bb = then_bb, other_bb = else_bb;
3279 else if ((trap = block_has_only_trap (else_bb)) != NULL)
3280 trap_bb = else_bb, other_bb = then_bb;
3286 fprintf (dump_file, "\nTRAP-IF block found, start %d, trap %d\n",
3287 test_bb->index, trap_bb->index);
3290 /* If this is not a standard conditional jump, we can't parse it. */
3291 jump = BB_END (test_bb);
3292 cond = noce_get_condition (jump, &cond_earliest, false);
3296 /* If the conditional jump is more than just a conditional jump, then
3297 we can not do if-conversion on this block. */
3298 if (! onlyjump_p (jump))
3301 /* We must be comparing objects whose modes imply the size. */
3302 if (GET_MODE (XEXP (cond, 0)) == BLKmode)
3305 /* Reverse the comparison code, if necessary. */
3306 code = GET_CODE (cond);
3307 if (then_bb == trap_bb)
3309 code = reversed_comparison_code (cond, jump);
3310 if (code == UNKNOWN)
3314 /* Attempt to generate the conditional trap. */
3315 seq = gen_cond_trap (code, copy_rtx (XEXP (cond, 0)),
3316 copy_rtx (XEXP (cond, 1)),
3317 TRAP_CODE (PATTERN (trap)));
3321 /* Emit the new insns before cond_earliest. */
3322 emit_insn_before_setloc (seq, cond_earliest, INSN_LOCATOR (trap));
3324 /* Delete the trap block if possible. */
3325 remove_edge (trap_bb == then_bb ? then_edge : else_edge);
3326 df_set_bb_dirty (test_bb);
3327 df_set_bb_dirty (then_bb);
3328 df_set_bb_dirty (else_bb);
3330 if (EDGE_COUNT (trap_bb->preds) == 0)
3332 delete_basic_block (trap_bb);
3336 /* Wire together the blocks again. */
3337 if (current_ir_type () == IR_RTL_CFGLAYOUT)
3338 single_succ_edge (test_bb)->flags |= EDGE_FALLTHRU;
3343 lab = JUMP_LABEL (jump);
3344 newjump = emit_jump_insn_after (gen_jump (lab), jump);
3345 LABEL_NUSES (lab) += 1;
3346 JUMP_LABEL (newjump) = lab;
3347 emit_barrier_after (newjump);
3351 if (can_merge_blocks_p (test_bb, other_bb))
3353 merge_blocks (test_bb, other_bb);
3357 num_updated_if_blocks++;
3361 /* Subroutine of find_cond_trap: if BB contains only a trap insn,
3365 block_has_only_trap (basic_block bb)
3369 /* We're not the exit block. */
3370 if (bb == EXIT_BLOCK_PTR)
3373 /* The block must have no successors. */
3374 if (EDGE_COUNT (bb->succs) > 0)
3377 /* The only instruction in the THEN block must be the trap. */
3378 trap = first_active_insn (bb);
3379 if (! (trap == BB_END (bb)
3380 && GET_CODE (PATTERN (trap)) == TRAP_IF
3381 && TRAP_CONDITION (PATTERN (trap)) == const_true_rtx))
3387 /* Look for IF-THEN-ELSE cases in which one of THEN or ELSE is
3388 transformable, but not necessarily the other. There need be no
3391 Return TRUE if we were successful at converting the block.
3393 Cases we'd like to look at:
3396 if (test) goto over; // x not live
3404 if (! test) goto label;
3407 if (test) goto E; // x not live
3421 (3) // This one's really only interesting for targets that can do
3422 // multiway branching, e.g. IA-64 BBB bundles. For other targets
3423 // it results in multiple branches on a cache line, which often
3424 // does not sit well with predictors.
3426 if (test1) goto E; // predicted not taken
3442 (A) Don't do (2) if the branch is predicted against the block we're
3443 eliminating. Do it anyway if we can eliminate a branch; this requires
3444 that the sole successor of the eliminated block postdominate the other
3447 (B) With CE, on (3) we can steal from both sides of the if, creating
3456 Again, this is most useful if J postdominates.
3458 (C) CE substitutes for helpful life information.
3460 (D) These heuristics need a lot of work. */
3462 /* Tests for case 1 above. */
3465 find_if_case_1 (basic_block test_bb, edge then_edge, edge else_edge)
3467 basic_block then_bb = then_edge->dest;
3468 basic_block else_bb = else_edge->dest;
3472 /* If we are partitioning hot/cold basic blocks, we don't want to
3473 mess up unconditional or indirect jumps that cross between hot
3476 Basic block partitioning may result in some jumps that appear to
3477 be optimizable (or blocks that appear to be mergeable), but which really
3478 must be left untouched (they are required to make it safely across
3479 partition boundaries). See the comments at the top of
3480 bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */
3482 if ((BB_END (then_bb)
3483 && find_reg_note (BB_END (then_bb), REG_CROSSING_JUMP, NULL_RTX))
3484 || (BB_END (test_bb)
3485 && find_reg_note (BB_END (test_bb), REG_CROSSING_JUMP, NULL_RTX))
3486 || (BB_END (else_bb)
3487 && find_reg_note (BB_END (else_bb), REG_CROSSING_JUMP,
3491 /* THEN has one successor. */
3492 if (!single_succ_p (then_bb))
3495 /* THEN does not fall through, but is not strange either. */
3496 if (single_succ_edge (then_bb)->flags & (EDGE_COMPLEX | EDGE_FALLTHRU))
3499 /* THEN has one predecessor. */
3500 if (!single_pred_p (then_bb))
3503 /* THEN must do something. */
3504 if (forwarder_block_p (then_bb))
3507 num_possible_if_blocks++;
3510 "\nIF-CASE-1 found, start %d, then %d\n",
3511 test_bb->index, then_bb->index);
3513 /* THEN is small. */
3514 if (! cheap_bb_rtx_cost_p (then_bb, COSTS_N_INSNS (BRANCH_COST)))
3517 /* Registers set are dead, or are predicable. */
3518 if (! dead_or_predicable (test_bb, then_bb, else_bb,
3519 single_succ (then_bb), 1))
3522 /* Conversion went ok, including moving the insns and fixing up the
3523 jump. Adjust the CFG to match. */
3525 /* We can avoid creating a new basic block if then_bb is immediately
3526 followed by else_bb, i.e. deleting then_bb allows test_bb to fall
3529 if (then_bb->next_bb == else_bb
3530 && then_bb->prev_bb == test_bb
3531 && else_bb != EXIT_BLOCK_PTR)
3533 redirect_edge_succ (FALLTHRU_EDGE (test_bb), else_bb);
3537 new_bb = redirect_edge_and_branch_force (FALLTHRU_EDGE (test_bb),
3540 df_set_bb_dirty (test_bb);
3541 df_set_bb_dirty (else_bb);
3543 then_bb_index = then_bb->index;
3544 delete_basic_block (then_bb);
3546 /* Make rest of code believe that the newly created block is the THEN_BB
3547 block we removed. */
3550 df_bb_replace (then_bb_index, new_bb);
3551 /* Since the fallthru edge was redirected from test_bb to new_bb,
3552 we need to ensure that new_bb is in the same partition as
3553 test bb (you can not fall through across section boundaries). */
3554 BB_COPY_PARTITION (new_bb, test_bb);
3558 num_updated_if_blocks++;
3563 /* Test for case 2 above. */
3566 find_if_case_2 (basic_block test_bb, edge then_edge, edge else_edge)
3568 basic_block then_bb = then_edge->dest;
3569 basic_block else_bb = else_edge->dest;
3573 /* If we are partitioning hot/cold basic blocks, we don't want to
3574 mess up unconditional or indirect jumps that cross between hot
3577 Basic block partitioning may result in some jumps that appear to
3578 be optimizable (or blocks that appear to be mergeable), but which really
3579 must be left untouched (they are required to make it safely across
3580 partition boundaries). See the comments at the top of
3581 bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */
3583 if ((BB_END (then_bb)
3584 && find_reg_note (BB_END (then_bb), REG_CROSSING_JUMP, NULL_RTX))
3585 || (BB_END (test_bb)
3586 && find_reg_note (BB_END (test_bb), REG_CROSSING_JUMP, NULL_RTX))
3587 || (BB_END (else_bb)
3588 && find_reg_note (BB_END (else_bb), REG_CROSSING_JUMP,
3592 /* ELSE has one successor. */
3593 if (!single_succ_p (else_bb))
3596 else_succ = single_succ_edge (else_bb);
3598 /* ELSE outgoing edge is not complex. */
3599 if (else_succ->flags & EDGE_COMPLEX)
3602 /* ELSE has one predecessor. */
3603 if (!single_pred_p (else_bb))
3606 /* THEN is not EXIT. */
3607 if (then_bb->index < NUM_FIXED_BLOCKS)
3610 /* ELSE is predicted or SUCC(ELSE) postdominates THEN. */
3611 note = find_reg_note (BB_END (test_bb), REG_BR_PROB, NULL_RTX);
3612 if (note && INTVAL (XEXP (note, 0)) >= REG_BR_PROB_BASE / 2)
3614 else if (else_succ->dest->index < NUM_FIXED_BLOCKS
3615 || dominated_by_p (CDI_POST_DOMINATORS, then_bb,
3621 num_possible_if_blocks++;
3624 "\nIF-CASE-2 found, start %d, else %d\n",
3625 test_bb->index, else_bb->index);
3627 /* ELSE is small. */
3628 if (! cheap_bb_rtx_cost_p (else_bb, COSTS_N_INSNS (BRANCH_COST)))
3631 /* Registers set are dead, or are predicable. */
3632 if (! dead_or_predicable (test_bb, else_bb, then_bb, else_succ->dest, 0))
3635 /* Conversion went ok, including moving the insns and fixing up the
3636 jump. Adjust the CFG to match. */
3638 df_set_bb_dirty (test_bb);
3639 df_set_bb_dirty (then_bb);
3640 delete_basic_block (else_bb);
3643 num_updated_if_blocks++;
3645 /* ??? We may now fallthru from one of THEN's successors into a join
3646 block. Rerun cleanup_cfg? Examine things manually? Wait? */
3651 /* A subroutine of dead_or_predicable called through for_each_rtx.
3652 Return 1 if a memory is found. */
3655 find_memory (rtx *px, void *data ATTRIBUTE_UNUSED)
3660 /* Used by the code above to perform the actual rtl transformations.
3661 Return TRUE if successful.
3663 TEST_BB is the block containing the conditional branch. MERGE_BB
3664 is the block containing the code to manipulate. NEW_DEST is the
3665 label TEST_BB should be branching to after the conversion.
3666 REVERSEP is true if the sense of the branch should be reversed. */
3669 dead_or_predicable (basic_block test_bb, basic_block merge_bb,
3670 basic_block other_bb, basic_block new_dest, int reversep)
3672 rtx head, end, jump, earliest = NULL_RTX, old_dest, new_label = NULL_RTX;
3674 jump = BB_END (test_bb);
3676 /* Find the extent of the real code in the merge block. */
3677 head = BB_HEAD (merge_bb);
3678 end = BB_END (merge_bb);
3680 /* If merge_bb ends with a tablejump, predicating/moving insn's
3681 into test_bb and then deleting merge_bb will result in the jumptable
3682 that follows merge_bb being removed along with merge_bb and then we
3683 get an unresolved reference to the jumptable. */
3684 if (tablejump_p (end, NULL, NULL))
3688 head = NEXT_INSN (head);
3693 head = end = NULL_RTX;
3696 head = NEXT_INSN (head);
3703 head = end = NULL_RTX;
3706 end = PREV_INSN (end);
3709 /* Disable handling dead code by conditional execution if the machine needs
3710 to do anything funny with the tests, etc. */
3711 #ifndef IFCVT_MODIFY_TESTS
3712 if (HAVE_conditional_execution)
3714 /* In the conditional execution case, we have things easy. We know
3715 the condition is reversible. We don't have to check life info
3716 because we're going to conditionally execute the code anyway.
3717 All that's left is making sure the insns involved can actually
3722 cond = cond_exec_get_condition (jump);
3726 prob_val = find_reg_note (jump, REG_BR_PROB, NULL_RTX);
3728 prob_val = XEXP (prob_val, 0);
3732 enum rtx_code rev = reversed_comparison_code (cond, jump);
3735 cond = gen_rtx_fmt_ee (rev, GET_MODE (cond), XEXP (cond, 0),
3738 prob_val = GEN_INT (REG_BR_PROB_BASE - INTVAL (prob_val));
3741 if (! cond_exec_process_insns ((ce_if_block_t *)0, head, end, cond,
3750 /* In the non-conditional execution case, we have to verify that there
3751 are no trapping operations, no calls, no references to memory, and
3752 that any registers modified are dead at the branch site. */
3754 rtx insn, cond, prev;
3755 bitmap merge_set, test_live, test_set;
3756 unsigned i, fail = 0;
3759 /* Check for no calls or trapping operations. */
3760 for (insn = head; ; insn = NEXT_INSN (insn))
3766 if (may_trap_p (PATTERN (insn)))
3769 /* ??? Even non-trapping memories such as stack frame
3770 references must be avoided. For stores, we collect
3771 no lifetime info; for reads, we'd have to assert
3772 true_dependence false against every store in the
3774 if (for_each_rtx (&PATTERN (insn), find_memory, NULL))
3781 if (! any_condjump_p (jump))
3784 /* Find the extent of the conditional. */
3785 cond = noce_get_condition (jump, &earliest, false);
3790 MERGE_SET = set of registers set in MERGE_BB
3791 TEST_LIVE = set of registers live at EARLIEST
3792 TEST_SET = set of registers set between EARLIEST and the
3793 end of the block. */
3795 merge_set = BITMAP_ALLOC (®_obstack);
3796 test_live = BITMAP_ALLOC (®_obstack);
3797 test_set = BITMAP_ALLOC (®_obstack);
3799 /* ??? bb->local_set is only valid during calculate_global_regs_live,
3800 so we must recompute usage for MERGE_BB. Not so bad, I suppose,
3801 since we've already asserted that MERGE_BB is small. */
3802 /* If we allocated new pseudos (e.g. in the conditional move
3803 expander called from noce_emit_cmove), we must resize the
3805 if (max_regno < max_reg_num ())
3806 max_regno = max_reg_num ();
3808 FOR_BB_INSNS (merge_bb, insn)
3812 unsigned int uid = INSN_UID (insn);
3813 struct df_ref **def_rec;
3814 for (def_rec = DF_INSN_UID_DEFS (uid); *def_rec; def_rec++)
3816 struct df_ref *def = *def_rec;
3817 bitmap_set_bit (merge_set, DF_REF_REGNO (def));
3822 /* For small register class machines, don't lengthen lifetimes of
3823 hard registers before reload. */
3824 if (SMALL_REGISTER_CLASSES && ! reload_completed)
3826 EXECUTE_IF_SET_IN_BITMAP (merge_set, 0, i, bi)
3828 if (i < FIRST_PSEUDO_REGISTER
3830 && ! global_regs[i])
3835 /* For TEST, we're interested in a range of insns, not a whole block.
3836 Moreover, we're interested in the insns live from OTHER_BB. */
3838 /* The loop below takes the set of live registers
3839 after JUMP, and calculates the live set before EARLIEST. */
3840 bitmap_copy (test_live, df_get_live_in (other_bb));
3841 df_simulate_artificial_refs_at_end (test_bb, test_live);
3842 for (insn = jump; ; insn = prev)
3846 df_simulate_find_defs (insn, test_set);
3847 df_simulate_one_insn_backwards (test_bb, insn, test_live);
3849 prev = PREV_INSN (insn);
3850 if (insn == earliest)
3854 /* We can perform the transformation if
3855 MERGE_SET & (TEST_SET | TEST_LIVE)
3857 TEST_SET & DF_LIVE_IN (merge_bb)
3860 if (bitmap_intersect_p (test_set, merge_set)
3861 || bitmap_intersect_p (test_live, merge_set)
3862 || bitmap_intersect_p (test_set, df_get_live_in (merge_bb)))
3865 BITMAP_FREE (merge_set);
3866 BITMAP_FREE (test_live);
3867 BITMAP_FREE (test_set);
3874 /* We don't want to use normal invert_jump or redirect_jump because
3875 we don't want to delete_insn called. Also, we want to do our own
3876 change group management. */
3878 old_dest = JUMP_LABEL (jump);
3879 if (other_bb != new_dest)
3881 new_label = block_label (new_dest);
3883 ? ! invert_jump_1 (jump, new_label)
3884 : ! redirect_jump_1 (jump, new_label))
3888 if (! apply_change_group ())
3891 if (other_bb != new_dest)
3893 redirect_jump_2 (jump, old_dest, new_label, 0, reversep);
3895 redirect_edge_succ (BRANCH_EDGE (test_bb), new_dest);
3898 gcov_type count, probability;
3899 count = BRANCH_EDGE (test_bb)->count;
3900 BRANCH_EDGE (test_bb)->count = FALLTHRU_EDGE (test_bb)->count;
3901 FALLTHRU_EDGE (test_bb)->count = count;
3902 probability = BRANCH_EDGE (test_bb)->probability;
3903 BRANCH_EDGE (test_bb)->probability
3904 = FALLTHRU_EDGE (test_bb)->probability;
3905 FALLTHRU_EDGE (test_bb)->probability = probability;
3906 update_br_prob_note (test_bb);
3910 /* Move the insns out of MERGE_BB to before the branch. */
3915 if (end == BB_END (merge_bb))
3916 BB_END (merge_bb) = PREV_INSN (head);
3918 /* PR 21767: When moving insns above a conditional branch, REG_EQUAL
3919 notes might become invalid. */
3925 if (! INSN_P (insn))
3927 note = find_reg_note (insn, REG_EQUAL, NULL_RTX);
3930 set = single_set (insn);
3931 if (!set || !function_invariant_p (SET_SRC (set)))
3932 remove_note (insn, note);
3933 } while (insn != end && (insn = NEXT_INSN (insn)));
3935 reorder_insns (head, end, PREV_INSN (earliest));
3938 /* Remove the jump and edge if we can. */
3939 if (other_bb == new_dest)
3942 remove_edge (BRANCH_EDGE (test_bb));
3943 /* ??? Can't merge blocks here, as then_bb is still in use.
3944 At minimum, the merge will get done just before bb-reorder. */
3954 /* Main entry point for all if-conversion. */
3957 if_convert (bool recompute_dominance)
3964 df_live_add_problem ();
3965 df_live_set_all_dirty ();
3968 num_possible_if_blocks = 0;
3969 num_updated_if_blocks = 0;
3970 num_true_changes = 0;
3972 loop_optimizer_init (AVOID_CFG_MODIFICATIONS);
3973 mark_loop_exit_edges ();
3974 loop_optimizer_finalize ();
3975 free_dominance_info (CDI_DOMINATORS);
3977 /* Compute postdominators if we think we'll use them. */
3978 if (HAVE_conditional_execution || recompute_dominance)
3979 calculate_dominance_info (CDI_POST_DOMINATORS);
3981 df_set_flags (DF_LR_RUN_DCE);
3983 /* Go through each of the basic blocks looking for things to convert. If we
3984 have conditional execution, we make multiple passes to allow us to handle
3985 IF-THEN{-ELSE} blocks within other IF-THEN{-ELSE} blocks. */
3990 /* Only need to do dce on the first pass. */
3991 df_clear_flags (DF_LR_RUN_DCE);
3992 cond_exec_changed_p = FALSE;
3995 #ifdef IFCVT_MULTIPLE_DUMPS
3996 if (dump_file && pass > 1)
3997 fprintf (dump_file, "\n\n========== Pass %d ==========\n", pass);
4003 while (!df_get_bb_dirty (bb)
4004 && (new_bb = find_if_header (bb, pass)) != NULL)
4008 #ifdef IFCVT_MULTIPLE_DUMPS
4009 if (dump_file && cond_exec_changed_p)
4010 print_rtl_with_bb (dump_file, get_insns ());
4013 while (cond_exec_changed_p);
4015 #ifdef IFCVT_MULTIPLE_DUMPS
4017 fprintf (dump_file, "\n\n========== no more changes\n");
4020 free_dominance_info (CDI_POST_DOMINATORS);
4025 clear_aux_for_blocks ();
4027 /* If we allocated new pseudos, we must resize the array for sched1. */
4028 if (max_regno < max_reg_num ())
4029 max_regno = max_reg_num ();
4031 /* Write the final stats. */
4032 if (dump_file && num_possible_if_blocks > 0)
4035 "\n%d possible IF blocks searched.\n",
4036 num_possible_if_blocks);
4038 "%d IF blocks converted.\n",
4039 num_updated_if_blocks);
4041 "%d true changes made.\n\n\n",
4046 df_remove_problem (df_live);
4048 #ifdef ENABLE_CHECKING
4049 verify_flow_info ();
4054 gate_handle_if_conversion (void)
4056 return (optimize > 0);
4059 /* If-conversion and CFG cleanup. */
4061 rest_of_handle_if_conversion (void)
4063 if (flag_if_conversion)
4066 dump_flow_info (dump_file, dump_flags);
4067 cleanup_cfg (CLEANUP_EXPENSIVE);
4075 struct tree_opt_pass pass_rtl_ifcvt =
4078 gate_handle_if_conversion, /* gate */
4079 rest_of_handle_if_conversion, /* execute */
4082 0, /* static_pass_number */
4083 TV_IFCVT, /* tv_id */
4084 0, /* properties_required */
4085 0, /* properties_provided */
4086 0, /* properties_destroyed */
4087 0, /* todo_flags_start */
4089 TODO_dump_func, /* todo_flags_finish */
4094 gate_handle_if_after_combine (void)
4096 return (optimize > 0 && flag_if_conversion);
4100 /* Rerun if-conversion, as combine may have simplified things enough
4101 to now meet sequence length restrictions. */
4103 rest_of_handle_if_after_combine (void)
4109 struct tree_opt_pass pass_if_after_combine =
4112 gate_handle_if_after_combine, /* gate */
4113 rest_of_handle_if_after_combine, /* execute */
4116 0, /* static_pass_number */
4117 TV_IFCVT, /* tv_id */
4118 0, /* properties_required */
4119 0, /* properties_provided */
4120 0, /* properties_destroyed */
4121 0, /* todo_flags_start */
4124 TODO_ggc_collect, /* todo_flags_finish */
4130 gate_handle_if_after_reload (void)
4132 return (optimize > 0 && flag_if_conversion2);
4136 rest_of_handle_if_after_reload (void)
4143 struct tree_opt_pass pass_if_after_reload =
4146 gate_handle_if_after_reload, /* gate */
4147 rest_of_handle_if_after_reload, /* execute */
4150 0, /* static_pass_number */
4151 TV_IFCVT2, /* tv_id */
4152 0, /* properties_required */
4153 0, /* properties_provided */
4154 0, /* properties_destroyed */
4155 0, /* todo_flags_start */
4158 TODO_ggc_collect, /* todo_flags_finish */