1 /* If-conversion support.
2 Copyright (C) 2000, 2001, 2002, 2003, 2004, 2005, 2006
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 2, 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 COPYING. If not, write to the Free
19 Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA
24 #include "coretypes.h"
31 #include "insn-config.h"
34 #include "hard-reg-set.h"
35 #include "basic-block.h"
45 #include "tree-pass.h"
50 #ifndef HAVE_conditional_execution
51 #define HAVE_conditional_execution 0
53 #ifndef HAVE_conditional_move
54 #define HAVE_conditional_move 0
65 #ifndef HAVE_conditional_trap
66 #define HAVE_conditional_trap 0
69 #ifndef MAX_CONDITIONAL_EXECUTE
70 #define MAX_CONDITIONAL_EXECUTE (BRANCH_COST + 1)
73 #define NULL_BLOCK ((basic_block) NULL)
75 /* # of IF-THEN or IF-THEN-ELSE blocks we looked at */
76 static int num_possible_if_blocks;
78 /* # of IF-THEN or IF-THEN-ELSE blocks were converted to conditional
80 static int num_updated_if_blocks;
82 /* # of changes made which require life information to be updated. */
83 static int num_true_changes;
85 /* Whether conditional execution changes were made. */
86 static int cond_exec_changed_p;
88 /* True if life data ok at present. */
89 static bool life_data_ok;
91 /* Forward references. */
92 static int count_bb_insns (basic_block);
93 static bool cheap_bb_rtx_cost_p (basic_block, int);
94 static rtx first_active_insn (basic_block);
95 static rtx last_active_insn (basic_block, int);
96 static basic_block block_fallthru (basic_block);
97 static int cond_exec_process_insns (ce_if_block_t *, rtx, rtx, rtx, rtx, int);
98 static rtx cond_exec_get_condition (rtx);
99 static int cond_exec_process_if_block (ce_if_block_t *, int);
100 static rtx noce_get_condition (rtx, rtx *);
101 static int noce_operand_ok (rtx);
102 static int noce_process_if_block (ce_if_block_t *);
103 static int process_if_block (ce_if_block_t *);
104 static void merge_if_block (ce_if_block_t *);
105 static int find_cond_trap (basic_block, edge, edge);
106 static basic_block find_if_header (basic_block, int);
107 static int block_jumps_and_fallthru_p (basic_block, basic_block);
108 static int find_if_block (ce_if_block_t *);
109 static int find_if_case_1 (basic_block, edge, edge);
110 static int find_if_case_2 (basic_block, edge, edge);
111 static int find_memory (rtx *, void *);
112 static int dead_or_predicable (basic_block, basic_block, basic_block,
114 static void noce_emit_move_insn (rtx, rtx);
115 static rtx block_has_only_trap (basic_block);
117 /* Count the number of non-jump active insns in BB. */
120 count_bb_insns (basic_block bb)
123 rtx insn = BB_HEAD (bb);
127 if (CALL_P (insn) || NONJUMP_INSN_P (insn))
130 if (insn == BB_END (bb))
132 insn = NEXT_INSN (insn);
138 /* Determine whether the total insn_rtx_cost on non-jump insns in
139 basic block BB is less than MAX_COST. This function returns
140 false if the cost of any instruction could not be estimated. */
143 cheap_bb_rtx_cost_p (basic_block bb, int max_cost)
146 rtx insn = BB_HEAD (bb);
150 if (NONJUMP_INSN_P (insn))
152 int cost = insn_rtx_cost (PATTERN (insn));
156 /* If this instruction is the load or set of a "stack" register,
157 such as a floating point register on x87, then the cost of
158 speculatively executing this insn may need to include
159 the additional cost of popping its result off of the
160 register stack. Unfortunately, correctly recognizing and
161 accounting for this additional overhead is tricky, so for
162 now we simply prohibit such speculative execution. */
165 rtx set = single_set (insn);
166 if (set && STACK_REG_P (SET_DEST (set)))
172 if (count >= max_cost)
175 else if (CALL_P (insn))
178 if (insn == BB_END (bb))
180 insn = NEXT_INSN (insn);
186 /* Return the first non-jump active insn in the basic block. */
189 first_active_insn (basic_block bb)
191 rtx insn = BB_HEAD (bb);
195 if (insn == BB_END (bb))
197 insn = NEXT_INSN (insn);
200 while (NOTE_P (insn))
202 if (insn == BB_END (bb))
204 insn = NEXT_INSN (insn);
213 /* Return the last non-jump active (non-jump) insn in the basic block. */
216 last_active_insn (basic_block bb, int skip_use_p)
218 rtx insn = BB_END (bb);
219 rtx head = BB_HEAD (bb);
224 && NONJUMP_INSN_P (insn)
225 && GET_CODE (PATTERN (insn)) == USE))
229 insn = PREV_INSN (insn);
238 /* Return the basic block reached by falling though the basic block BB. */
241 block_fallthru (basic_block bb)
246 FOR_EACH_EDGE (e, ei, bb->succs)
247 if (e->flags & EDGE_FALLTHRU)
250 return (e) ? e->dest : NULL_BLOCK;
253 /* Go through a bunch of insns, converting them to conditional
254 execution format if possible. Return TRUE if all of the non-note
255 insns were processed. */
258 cond_exec_process_insns (ce_if_block_t *ce_info ATTRIBUTE_UNUSED,
259 /* if block information */rtx start,
260 /* first insn to look at */rtx end,
261 /* last insn to look at */rtx test,
262 /* conditional execution test */rtx prob_val,
263 /* probability of branch taken. */int mod_ok)
265 int must_be_last = FALSE;
273 for (insn = start; ; insn = NEXT_INSN (insn))
278 gcc_assert(NONJUMP_INSN_P (insn) || CALL_P (insn));
280 /* Remove USE insns that get in the way. */
281 if (reload_completed && GET_CODE (PATTERN (insn)) == USE)
283 /* ??? Ug. Actually unlinking the thing is problematic,
284 given what we'd have to coordinate with our callers. */
285 SET_INSN_DELETED (insn);
289 /* Last insn wasn't last? */
293 if (modified_in_p (test, insn))
300 /* Now build the conditional form of the instruction. */
301 pattern = PATTERN (insn);
302 xtest = copy_rtx (test);
304 /* If this is already a COND_EXEC, rewrite the test to be an AND of the
306 if (GET_CODE (pattern) == COND_EXEC)
308 if (GET_MODE (xtest) != GET_MODE (COND_EXEC_TEST (pattern)))
311 xtest = gen_rtx_AND (GET_MODE (xtest), xtest,
312 COND_EXEC_TEST (pattern));
313 pattern = COND_EXEC_CODE (pattern);
316 pattern = gen_rtx_COND_EXEC (VOIDmode, xtest, pattern);
318 /* If the machine needs to modify the insn being conditionally executed,
319 say for example to force a constant integer operand into a temp
320 register, do so here. */
321 #ifdef IFCVT_MODIFY_INSN
322 IFCVT_MODIFY_INSN (ce_info, pattern, insn);
327 validate_change (insn, &PATTERN (insn), pattern, 1);
329 if (CALL_P (insn) && prob_val)
330 validate_change (insn, ®_NOTES (insn),
331 alloc_EXPR_LIST (REG_BR_PROB, prob_val,
332 REG_NOTES (insn)), 1);
342 /* Return the condition for a jump. Do not do any special processing. */
345 cond_exec_get_condition (rtx jump)
349 if (any_condjump_p (jump))
350 test_if = SET_SRC (pc_set (jump));
353 cond = XEXP (test_if, 0);
355 /* If this branches to JUMP_LABEL when the condition is false,
356 reverse the condition. */
357 if (GET_CODE (XEXP (test_if, 2)) == LABEL_REF
358 && XEXP (XEXP (test_if, 2), 0) == JUMP_LABEL (jump))
360 enum rtx_code rev = reversed_comparison_code (cond, jump);
364 cond = gen_rtx_fmt_ee (rev, GET_MODE (cond), XEXP (cond, 0),
371 /* Given a simple IF-THEN or IF-THEN-ELSE block, attempt to convert it
372 to conditional execution. Return TRUE if we were successful at
373 converting the block. */
376 cond_exec_process_if_block (ce_if_block_t * ce_info,
377 /* if block information */int do_multiple_p)
379 basic_block test_bb = ce_info->test_bb; /* last test block */
380 basic_block then_bb = ce_info->then_bb; /* THEN */
381 basic_block else_bb = ce_info->else_bb; /* ELSE or NULL */
382 rtx test_expr; /* expression in IF_THEN_ELSE that is tested */
383 rtx then_start; /* first insn in THEN block */
384 rtx then_end; /* last insn + 1 in THEN block */
385 rtx else_start = NULL_RTX; /* first insn in ELSE block or NULL */
386 rtx else_end = NULL_RTX; /* last insn + 1 in ELSE block */
387 int max; /* max # of insns to convert. */
388 int then_mod_ok; /* whether conditional mods are ok in THEN */
389 rtx true_expr; /* test for else block insns */
390 rtx false_expr; /* test for then block insns */
391 rtx true_prob_val; /* probability of else block */
392 rtx false_prob_val; /* probability of then block */
394 enum rtx_code false_code;
396 /* If test is comprised of && or || elements, and we've failed at handling
397 all of them together, just use the last test if it is the special case of
398 && elements without an ELSE block. */
399 if (!do_multiple_p && ce_info->num_multiple_test_blocks)
401 if (else_bb || ! ce_info->and_and_p)
404 ce_info->test_bb = test_bb = ce_info->last_test_bb;
405 ce_info->num_multiple_test_blocks = 0;
406 ce_info->num_and_and_blocks = 0;
407 ce_info->num_or_or_blocks = 0;
410 /* Find the conditional jump to the ELSE or JOIN part, and isolate
412 test_expr = cond_exec_get_condition (BB_END (test_bb));
416 /* If the conditional jump is more than just a conditional jump,
417 then we can not do conditional execution conversion on this block. */
418 if (! onlyjump_p (BB_END (test_bb)))
421 /* Collect the bounds of where we're to search, skipping any labels, jumps
422 and notes at the beginning and end of the block. Then count the total
423 number of insns and see if it is small enough to convert. */
424 then_start = first_active_insn (then_bb);
425 then_end = last_active_insn (then_bb, TRUE);
426 n_insns = ce_info->num_then_insns = count_bb_insns (then_bb);
427 max = MAX_CONDITIONAL_EXECUTE;
432 else_start = first_active_insn (else_bb);
433 else_end = last_active_insn (else_bb, TRUE);
434 n_insns += ce_info->num_else_insns = count_bb_insns (else_bb);
440 /* Map test_expr/test_jump into the appropriate MD tests to use on
441 the conditionally executed code. */
443 true_expr = test_expr;
445 false_code = reversed_comparison_code (true_expr, BB_END (test_bb));
446 if (false_code != UNKNOWN)
447 false_expr = gen_rtx_fmt_ee (false_code, GET_MODE (true_expr),
448 XEXP (true_expr, 0), XEXP (true_expr, 1));
450 false_expr = NULL_RTX;
452 #ifdef IFCVT_MODIFY_TESTS
453 /* If the machine description needs to modify the tests, such as setting a
454 conditional execution register from a comparison, it can do so here. */
455 IFCVT_MODIFY_TESTS (ce_info, true_expr, false_expr);
457 /* See if the conversion failed. */
458 if (!true_expr || !false_expr)
462 true_prob_val = find_reg_note (BB_END (test_bb), REG_BR_PROB, NULL_RTX);
465 true_prob_val = XEXP (true_prob_val, 0);
466 false_prob_val = GEN_INT (REG_BR_PROB_BASE - INTVAL (true_prob_val));
469 false_prob_val = NULL_RTX;
471 /* If we have && or || tests, do them here. These tests are in the adjacent
472 blocks after the first block containing the test. */
473 if (ce_info->num_multiple_test_blocks > 0)
475 basic_block bb = test_bb;
476 basic_block last_test_bb = ce_info->last_test_bb;
485 enum rtx_code f_code;
487 bb = block_fallthru (bb);
488 start = first_active_insn (bb);
489 end = last_active_insn (bb, TRUE);
491 && ! cond_exec_process_insns (ce_info, start, end, false_expr,
492 false_prob_val, FALSE))
495 /* If the conditional jump is more than just a conditional jump, then
496 we can not do conditional execution conversion on this block. */
497 if (! onlyjump_p (BB_END (bb)))
500 /* Find the conditional jump and isolate the test. */
501 t = cond_exec_get_condition (BB_END (bb));
505 f_code = reversed_comparison_code (t, BB_END (bb));
506 if (f_code == UNKNOWN)
509 f = gen_rtx_fmt_ee (f_code, GET_MODE (t), XEXP (t, 0), XEXP (t, 1));
510 if (ce_info->and_and_p)
512 t = gen_rtx_AND (GET_MODE (t), true_expr, t);
513 f = gen_rtx_IOR (GET_MODE (t), false_expr, f);
517 t = gen_rtx_IOR (GET_MODE (t), true_expr, t);
518 f = gen_rtx_AND (GET_MODE (t), false_expr, f);
521 /* If the machine description needs to modify the tests, such as
522 setting a conditional execution register from a comparison, it can
524 #ifdef IFCVT_MODIFY_MULTIPLE_TESTS
525 IFCVT_MODIFY_MULTIPLE_TESTS (ce_info, bb, t, f);
527 /* See if the conversion failed. */
535 while (bb != last_test_bb);
538 /* For IF-THEN-ELSE blocks, we don't allow modifications of the test
539 on then THEN block. */
540 then_mod_ok = (else_bb == NULL_BLOCK);
542 /* Go through the THEN and ELSE blocks converting the insns if possible
543 to conditional execution. */
547 || ! cond_exec_process_insns (ce_info, then_start, then_end,
548 false_expr, false_prob_val,
552 if (else_bb && else_end
553 && ! cond_exec_process_insns (ce_info, else_start, else_end,
554 true_expr, true_prob_val, TRUE))
557 /* If we cannot apply the changes, fail. Do not go through the normal fail
558 processing, since apply_change_group will call cancel_changes. */
559 if (! apply_change_group ())
561 #ifdef IFCVT_MODIFY_CANCEL
562 /* Cancel any machine dependent changes. */
563 IFCVT_MODIFY_CANCEL (ce_info);
568 #ifdef IFCVT_MODIFY_FINAL
569 /* Do any machine dependent final modifications. */
570 IFCVT_MODIFY_FINAL (ce_info);
573 /* Conversion succeeded. */
575 fprintf (dump_file, "%d insn%s converted to conditional execution.\n",
576 n_insns, (n_insns == 1) ? " was" : "s were");
578 /* Merge the blocks! */
579 merge_if_block (ce_info);
580 cond_exec_changed_p = TRUE;
584 #ifdef IFCVT_MODIFY_CANCEL
585 /* Cancel any machine dependent changes. */
586 IFCVT_MODIFY_CANCEL (ce_info);
593 /* Used by noce_process_if_block to communicate with its subroutines.
595 The subroutines know that A and B may be evaluated freely. They
596 know that X is a register. They should insert new instructions
597 before cond_earliest. */
601 /* A basic block that ends in a simple conditional jump. */
604 /* The jump that ends TEST_BB. */
607 /* The jump condition. */
610 /* New insns should be inserted before this one. */
613 /* Insns in the THEN and ELSE block. There is always just this
614 one insns in those blocks. The insns are single_set insns.
615 If there was no ELSE block, INSN_B is the last insn before
616 COND_EARLIEST, or NULL_RTX. In the former case, the insn
617 operands are still valid, as if INSN_B was moved down below
621 /* The SET_SRC of INSN_A and INSN_B. */
624 /* The SET_DEST of INSN_A. */
628 static rtx noce_emit_store_flag (struct noce_if_info *, rtx, int, int);
629 static int noce_try_move (struct noce_if_info *);
630 static int noce_try_store_flag (struct noce_if_info *);
631 static int noce_try_addcc (struct noce_if_info *);
632 static int noce_try_store_flag_constants (struct noce_if_info *);
633 static int noce_try_store_flag_mask (struct noce_if_info *);
634 static rtx noce_emit_cmove (struct noce_if_info *, rtx, enum rtx_code, rtx,
636 static int noce_try_cmove (struct noce_if_info *);
637 static int noce_try_cmove_arith (struct noce_if_info *);
638 static rtx noce_get_alt_condition (struct noce_if_info *, rtx, rtx *);
639 static int noce_try_minmax (struct noce_if_info *);
640 static int noce_try_abs (struct noce_if_info *);
641 static int noce_try_sign_mask (struct noce_if_info *);
643 /* Helper function for noce_try_store_flag*. */
646 noce_emit_store_flag (struct noce_if_info *if_info, rtx x, int reversep,
649 rtx cond = if_info->cond;
653 cond_complex = (! general_operand (XEXP (cond, 0), VOIDmode)
654 || ! general_operand (XEXP (cond, 1), VOIDmode));
656 /* If earliest == jump, or when the condition is complex, try to
657 build the store_flag insn directly. */
660 cond = XEXP (SET_SRC (pc_set (if_info->jump)), 0);
663 code = reversed_comparison_code (cond, if_info->jump);
665 code = GET_CODE (cond);
667 if ((if_info->cond_earliest == if_info->jump || cond_complex)
668 && (normalize == 0 || STORE_FLAG_VALUE == normalize))
672 tmp = gen_rtx_fmt_ee (code, GET_MODE (x), XEXP (cond, 0),
674 tmp = gen_rtx_SET (VOIDmode, x, tmp);
677 tmp = emit_insn (tmp);
679 if (recog_memoized (tmp) >= 0)
685 if_info->cond_earliest = if_info->jump;
693 /* Don't even try if the comparison operands or the mode of X are weird. */
694 if (cond_complex || !SCALAR_INT_MODE_P (GET_MODE (x)))
697 return emit_store_flag (x, code, XEXP (cond, 0),
698 XEXP (cond, 1), VOIDmode,
699 (code == LTU || code == LEU
700 || code == GEU || code == GTU), normalize);
703 /* Emit instruction to move an rtx, possibly into STRICT_LOW_PART.
704 X is the destination/target and Y is the value to copy. */
707 noce_emit_move_insn (rtx x, rtx y)
709 enum machine_mode outmode;
713 if (GET_CODE (x) != STRICT_LOW_PART)
715 rtx seq, insn, target;
719 /* Check that the SET_SRC is reasonable before calling emit_move_insn,
720 otherwise construct a suitable SET pattern ourselves. */
721 insn = (OBJECT_P (y) || CONSTANT_P (y) || GET_CODE (y) == SUBREG)
722 ? emit_move_insn (x, y)
723 : emit_insn (gen_rtx_SET (VOIDmode, x, y));
727 if (recog_memoized (insn) <= 0)
729 if (GET_CODE (x) == ZERO_EXTRACT)
731 rtx op = XEXP (x, 0);
732 unsigned HOST_WIDE_INT size = INTVAL (XEXP (x, 1));
733 unsigned HOST_WIDE_INT start = INTVAL (XEXP (x, 2));
735 /* store_bit_field expects START to be relative to
736 BYTES_BIG_ENDIAN and adjusts this value for machines with
737 BITS_BIG_ENDIAN != BYTES_BIG_ENDIAN. In order to be able to
738 invoke store_bit_field again it is necessary to have the START
739 value from the first call. */
740 if (BITS_BIG_ENDIAN != BYTES_BIG_ENDIAN)
743 start = BITS_PER_UNIT - start - size;
746 gcc_assert (REG_P (op));
747 start = BITS_PER_WORD - start - size;
751 gcc_assert (start < (MEM_P (op) ? BITS_PER_UNIT : BITS_PER_WORD));
752 store_bit_field (op, size, start, GET_MODE (x), y);
756 switch (GET_RTX_CLASS (GET_CODE (y)))
759 ot = code_to_optab[GET_CODE (y)];
763 target = expand_unop (GET_MODE (y), ot, XEXP (y, 0), x, 0);
764 if (target != NULL_RTX)
767 emit_move_insn (x, target);
776 ot = code_to_optab[GET_CODE (y)];
780 target = expand_binop (GET_MODE (y), ot,
781 XEXP (y, 0), XEXP (y, 1),
783 if (target != NULL_RTX)
786 emit_move_insn (x, target);
803 inner = XEXP (outer, 0);
804 outmode = GET_MODE (outer);
805 bitpos = SUBREG_BYTE (outer) * BITS_PER_UNIT;
806 store_bit_field (inner, GET_MODE_BITSIZE (outmode), bitpos, outmode, y);
809 /* Return sequence of instructions generated by if conversion. This
810 function calls end_sequence() to end the current stream, ensures
811 that are instructions are unshared, recognizable non-jump insns.
812 On failure, this function returns a NULL_RTX. */
815 end_ifcvt_sequence (struct noce_if_info *if_info)
818 rtx seq = get_insns ();
820 set_used_flags (if_info->x);
821 set_used_flags (if_info->cond);
822 unshare_all_rtl_in_chain (seq);
825 /* Make sure that all of the instructions emitted are recognizable,
826 and that we haven't introduced a new jump instruction.
827 As an exercise for the reader, build a general mechanism that
828 allows proper placement of required clobbers. */
829 for (insn = seq; insn; insn = NEXT_INSN (insn))
831 || recog_memoized (insn) == -1)
837 /* Convert "if (a != b) x = a; else x = b" into "x = a" and
838 "if (a == b) x = a; else x = b" into "x = b". */
841 noce_try_move (struct noce_if_info *if_info)
843 rtx cond = if_info->cond;
844 enum rtx_code code = GET_CODE (cond);
847 if (code != NE && code != EQ)
850 /* This optimization isn't valid if either A or B could be a NaN
852 if (HONOR_NANS (GET_MODE (if_info->x))
853 || HONOR_SIGNED_ZEROS (GET_MODE (if_info->x)))
856 /* Check whether the operands of the comparison are A and in
858 if ((rtx_equal_p (if_info->a, XEXP (cond, 0))
859 && rtx_equal_p (if_info->b, XEXP (cond, 1)))
860 || (rtx_equal_p (if_info->a, XEXP (cond, 1))
861 && rtx_equal_p (if_info->b, XEXP (cond, 0))))
863 y = (code == EQ) ? if_info->a : if_info->b;
865 /* Avoid generating the move if the source is the destination. */
866 if (! rtx_equal_p (if_info->x, y))
869 noce_emit_move_insn (if_info->x, y);
870 seq = end_ifcvt_sequence (if_info);
874 emit_insn_before_setloc (seq, if_info->jump,
875 INSN_LOCATOR (if_info->insn_a));
882 /* Convert "if (test) x = 1; else x = 0".
884 Only try 0 and STORE_FLAG_VALUE here. Other combinations will be
885 tried in noce_try_store_flag_constants after noce_try_cmove has had
886 a go at the conversion. */
889 noce_try_store_flag (struct noce_if_info *if_info)
894 if (GET_CODE (if_info->b) == CONST_INT
895 && INTVAL (if_info->b) == STORE_FLAG_VALUE
896 && if_info->a == const0_rtx)
898 else if (if_info->b == const0_rtx
899 && GET_CODE (if_info->a) == CONST_INT
900 && INTVAL (if_info->a) == STORE_FLAG_VALUE
901 && (reversed_comparison_code (if_info->cond, if_info->jump)
909 target = noce_emit_store_flag (if_info, if_info->x, reversep, 0);
912 if (target != if_info->x)
913 noce_emit_move_insn (if_info->x, target);
915 seq = end_ifcvt_sequence (if_info);
919 emit_insn_before_setloc (seq, if_info->jump,
920 INSN_LOCATOR (if_info->insn_a));
930 /* Convert "if (test) x = a; else x = b", for A and B constant. */
933 noce_try_store_flag_constants (struct noce_if_info *if_info)
937 HOST_WIDE_INT itrue, ifalse, diff, tmp;
938 int normalize, can_reverse;
939 enum machine_mode mode;
942 && GET_CODE (if_info->a) == CONST_INT
943 && GET_CODE (if_info->b) == CONST_INT)
945 mode = GET_MODE (if_info->x);
946 ifalse = INTVAL (if_info->a);
947 itrue = INTVAL (if_info->b);
949 /* Make sure we can represent the difference between the two values. */
950 if ((itrue - ifalse > 0)
951 != ((ifalse < 0) != (itrue < 0) ? ifalse < 0 : ifalse < itrue))
954 diff = trunc_int_for_mode (itrue - ifalse, mode);
956 can_reverse = (reversed_comparison_code (if_info->cond, if_info->jump)
960 if (diff == STORE_FLAG_VALUE || diff == -STORE_FLAG_VALUE)
962 else if (ifalse == 0 && exact_log2 (itrue) >= 0
963 && (STORE_FLAG_VALUE == 1
964 || BRANCH_COST >= 2))
966 else if (itrue == 0 && exact_log2 (ifalse) >= 0 && can_reverse
967 && (STORE_FLAG_VALUE == 1 || BRANCH_COST >= 2))
968 normalize = 1, reversep = 1;
970 && (STORE_FLAG_VALUE == -1
971 || BRANCH_COST >= 2))
973 else if (ifalse == -1 && can_reverse
974 && (STORE_FLAG_VALUE == -1 || BRANCH_COST >= 2))
975 normalize = -1, reversep = 1;
976 else if ((BRANCH_COST >= 2 && STORE_FLAG_VALUE == -1)
984 tmp = itrue; itrue = ifalse; ifalse = tmp;
985 diff = trunc_int_for_mode (-diff, mode);
989 target = noce_emit_store_flag (if_info, if_info->x, reversep, normalize);
996 /* if (test) x = 3; else x = 4;
997 => x = 3 + (test == 0); */
998 if (diff == STORE_FLAG_VALUE || diff == -STORE_FLAG_VALUE)
1000 target = expand_simple_binop (mode,
1001 (diff == STORE_FLAG_VALUE
1003 GEN_INT (ifalse), target, if_info->x, 0,
1007 /* if (test) x = 8; else x = 0;
1008 => x = (test != 0) << 3; */
1009 else if (ifalse == 0 && (tmp = exact_log2 (itrue)) >= 0)
1011 target = expand_simple_binop (mode, ASHIFT,
1012 target, GEN_INT (tmp), if_info->x, 0,
1016 /* if (test) x = -1; else x = b;
1017 => x = -(test != 0) | b; */
1018 else if (itrue == -1)
1020 target = expand_simple_binop (mode, IOR,
1021 target, GEN_INT (ifalse), if_info->x, 0,
1025 /* if (test) x = a; else x = b;
1026 => x = (-(test != 0) & (b - a)) + a; */
1029 target = expand_simple_binop (mode, AND,
1030 target, GEN_INT (diff), if_info->x, 0,
1033 target = expand_simple_binop (mode, PLUS,
1034 target, GEN_INT (ifalse),
1035 if_info->x, 0, OPTAB_WIDEN);
1044 if (target != if_info->x)
1045 noce_emit_move_insn (if_info->x, target);
1047 seq = end_ifcvt_sequence (if_info);
1051 emit_insn_before_setloc (seq, if_info->jump,
1052 INSN_LOCATOR (if_info->insn_a));
1059 /* Convert "if (test) foo++" into "foo += (test != 0)", and
1060 similarly for "foo--". */
1063 noce_try_addcc (struct noce_if_info *if_info)
1066 int subtract, normalize;
1068 if (! no_new_pseudos
1069 && 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 (! no_new_pseudos
1161 && (BRANCH_COST >= 2
1162 || STORE_FLAG_VALUE == -1)
1163 && ((if_info->a == const0_rtx
1164 && rtx_equal_p (if_info->b, if_info->x))
1165 || ((reversep = (reversed_comparison_code (if_info->cond,
1168 && if_info->b == const0_rtx
1169 && rtx_equal_p (if_info->a, if_info->x))))
1172 target = noce_emit_store_flag (if_info,
1173 gen_reg_rtx (GET_MODE (if_info->x)),
1176 target = expand_simple_binop (GET_MODE (if_info->x), AND,
1178 target, if_info->x, 0,
1183 if (target != if_info->x)
1184 noce_emit_move_insn (if_info->x, target);
1186 seq = end_ifcvt_sequence (if_info);
1190 emit_insn_before_setloc (seq, if_info->jump,
1191 INSN_LOCATOR (if_info->insn_a));
1201 /* Helper function for noce_try_cmove and noce_try_cmove_arith. */
1204 noce_emit_cmove (struct noce_if_info *if_info, rtx x, enum rtx_code code,
1205 rtx cmp_a, rtx cmp_b, rtx vfalse, rtx vtrue)
1207 /* If earliest == jump, try to build the cmove insn directly.
1208 This is helpful when combine has created some complex condition
1209 (like for alpha's cmovlbs) that we can't hope to regenerate
1210 through the normal interface. */
1212 if (if_info->cond_earliest == if_info->jump)
1216 tmp = gen_rtx_fmt_ee (code, GET_MODE (if_info->cond), cmp_a, cmp_b);
1217 tmp = gen_rtx_IF_THEN_ELSE (GET_MODE (x), tmp, vtrue, vfalse);
1218 tmp = gen_rtx_SET (VOIDmode, x, tmp);
1221 tmp = emit_insn (tmp);
1223 if (recog_memoized (tmp) >= 0)
1235 /* Don't even try if the comparison operands are weird. */
1236 if (! general_operand (cmp_a, GET_MODE (cmp_a))
1237 || ! general_operand (cmp_b, GET_MODE (cmp_b)))
1240 #if HAVE_conditional_move
1241 return emit_conditional_move (x, code, cmp_a, cmp_b, VOIDmode,
1242 vtrue, vfalse, GET_MODE (x),
1243 (code == LTU || code == GEU
1244 || code == LEU || code == GTU));
1246 /* We'll never get here, as noce_process_if_block doesn't call the
1247 functions involved. Ifdef code, however, should be discouraged
1248 because it leads to typos in the code not selected. However,
1249 emit_conditional_move won't exist either. */
1254 /* Try only simple constants and registers here. More complex cases
1255 are handled in noce_try_cmove_arith after noce_try_store_flag_arith
1256 has had a go at it. */
1259 noce_try_cmove (struct noce_if_info *if_info)
1264 if ((CONSTANT_P (if_info->a) || register_operand (if_info->a, VOIDmode))
1265 && (CONSTANT_P (if_info->b) || register_operand (if_info->b, VOIDmode)))
1269 code = GET_CODE (if_info->cond);
1270 target = noce_emit_cmove (if_info, if_info->x, code,
1271 XEXP (if_info->cond, 0),
1272 XEXP (if_info->cond, 1),
1273 if_info->a, if_info->b);
1277 if (target != if_info->x)
1278 noce_emit_move_insn (if_info->x, target);
1280 seq = end_ifcvt_sequence (if_info);
1284 emit_insn_before_setloc (seq, if_info->jump,
1285 INSN_LOCATOR (if_info->insn_a));
1298 /* Try more complex cases involving conditional_move. */
1301 noce_try_cmove_arith (struct noce_if_info *if_info)
1313 /* A conditional move from two memory sources is equivalent to a
1314 conditional on their addresses followed by a load. Don't do this
1315 early because it'll screw alias analysis. Note that we've
1316 already checked for no side effects. */
1317 if (! no_new_pseudos && 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)))
1393 goto end_seq_and_fail;
1397 tmp = gen_reg_rtx (GET_MODE (a));
1398 tmp = emit_insn (gen_rtx_SET (VOIDmode, tmp, a));
1401 goto end_seq_and_fail;
1404 a = gen_reg_rtx (GET_MODE (a));
1405 tmp = copy_rtx (insn_a);
1406 set = single_set (tmp);
1408 tmp = emit_insn (PATTERN (tmp));
1410 if (recog_memoized (tmp) < 0)
1411 goto end_seq_and_fail;
1413 if (! general_operand (b, GET_MODE (b)))
1418 goto end_seq_and_fail;
1422 tmp = gen_reg_rtx (GET_MODE (b));
1423 tmp = gen_rtx_SET (VOIDmode, tmp, b);
1426 goto end_seq_and_fail;
1429 b = gen_reg_rtx (GET_MODE (b));
1430 tmp = copy_rtx (insn_b);
1431 set = single_set (tmp);
1433 tmp = PATTERN (tmp);
1436 /* If insn to set up A clobbers any registers B depends on, try to
1437 swap insn that sets up A with the one that sets up B. If even
1438 that doesn't help, punt. */
1439 last = get_last_insn ();
1440 if (last && modified_in_p (orig_b, last))
1442 tmp = emit_insn_before (tmp, get_insns ());
1443 if (modified_in_p (orig_a, tmp))
1444 goto end_seq_and_fail;
1447 tmp = emit_insn (tmp);
1449 if (recog_memoized (tmp) < 0)
1450 goto end_seq_and_fail;
1453 target = noce_emit_cmove (if_info, x, code, XEXP (if_info->cond, 0),
1454 XEXP (if_info->cond, 1), a, b);
1457 goto end_seq_and_fail;
1459 /* If we're handling a memory for above, emit the load now. */
1462 tmp = gen_rtx_MEM (GET_MODE (if_info->x), target);
1464 /* Copy over flags as appropriate. */
1465 if (MEM_VOLATILE_P (if_info->a) || MEM_VOLATILE_P (if_info->b))
1466 MEM_VOLATILE_P (tmp) = 1;
1467 if (MEM_IN_STRUCT_P (if_info->a) && MEM_IN_STRUCT_P (if_info->b))
1468 MEM_IN_STRUCT_P (tmp) = 1;
1469 if (MEM_SCALAR_P (if_info->a) && MEM_SCALAR_P (if_info->b))
1470 MEM_SCALAR_P (tmp) = 1;
1471 if (MEM_ALIAS_SET (if_info->a) == MEM_ALIAS_SET (if_info->b))
1472 set_mem_alias_set (tmp, MEM_ALIAS_SET (if_info->a));
1474 MIN (MEM_ALIGN (if_info->a), MEM_ALIGN (if_info->b)));
1476 noce_emit_move_insn (if_info->x, tmp);
1478 else if (target != x)
1479 noce_emit_move_insn (x, target);
1481 tmp = end_ifcvt_sequence (if_info);
1485 emit_insn_before_setloc (tmp, if_info->jump, INSN_LOCATOR (if_info->insn_a));
1493 /* For most cases, the simplified condition we found is the best
1494 choice, but this is not the case for the min/max/abs transforms.
1495 For these we wish to know that it is A or B in the condition. */
1498 noce_get_alt_condition (struct noce_if_info *if_info, rtx target,
1501 rtx cond, set, insn;
1504 /* If target is already mentioned in the known condition, return it. */
1505 if (reg_mentioned_p (target, if_info->cond))
1507 *earliest = if_info->cond_earliest;
1508 return if_info->cond;
1511 set = pc_set (if_info->jump);
1512 cond = XEXP (SET_SRC (set), 0);
1514 = GET_CODE (XEXP (SET_SRC (set), 2)) == LABEL_REF
1515 && XEXP (XEXP (SET_SRC (set), 2), 0) == JUMP_LABEL (if_info->jump);
1517 /* If we're looking for a constant, try to make the conditional
1518 have that constant in it. There are two reasons why it may
1519 not have the constant we want:
1521 1. GCC may have needed to put the constant in a register, because
1522 the target can't compare directly against that constant. For
1523 this case, we look for a SET immediately before the comparison
1524 that puts a constant in that register.
1526 2. GCC may have canonicalized the conditional, for example
1527 replacing "if x < 4" with "if x <= 3". We can undo that (or
1528 make equivalent types of changes) to get the constants we need
1529 if they're off by one in the right direction. */
1531 if (GET_CODE (target) == CONST_INT)
1533 enum rtx_code code = GET_CODE (if_info->cond);
1534 rtx op_a = XEXP (if_info->cond, 0);
1535 rtx op_b = XEXP (if_info->cond, 1);
1538 /* First, look to see if we put a constant in a register. */
1539 prev_insn = prev_nonnote_insn (if_info->cond_earliest);
1541 && INSN_P (prev_insn)
1542 && GET_CODE (PATTERN (prev_insn)) == SET)
1544 rtx src = find_reg_equal_equiv_note (prev_insn);
1546 src = SET_SRC (PATTERN (prev_insn));
1547 if (GET_CODE (src) == CONST_INT)
1549 if (rtx_equal_p (op_a, SET_DEST (PATTERN (prev_insn))))
1551 else if (rtx_equal_p (op_b, SET_DEST (PATTERN (prev_insn))))
1554 if (GET_CODE (op_a) == CONST_INT)
1559 code = swap_condition (code);
1564 /* Now, look to see if we can get the right constant by
1565 adjusting the conditional. */
1566 if (GET_CODE (op_b) == CONST_INT)
1568 HOST_WIDE_INT desired_val = INTVAL (target);
1569 HOST_WIDE_INT actual_val = INTVAL (op_b);
1574 if (actual_val == desired_val + 1)
1577 op_b = GEN_INT (desired_val);
1581 if (actual_val == desired_val - 1)
1584 op_b = GEN_INT (desired_val);
1588 if (actual_val == desired_val - 1)
1591 op_b = GEN_INT (desired_val);
1595 if (actual_val == desired_val + 1)
1598 op_b = GEN_INT (desired_val);
1606 /* If we made any changes, generate a new conditional that is
1607 equivalent to what we started with, but has the right
1609 if (code != GET_CODE (if_info->cond)
1610 || op_a != XEXP (if_info->cond, 0)
1611 || op_b != XEXP (if_info->cond, 1))
1613 cond = gen_rtx_fmt_ee (code, GET_MODE (cond), op_a, op_b);
1614 *earliest = if_info->cond_earliest;
1619 cond = canonicalize_condition (if_info->jump, cond, reverse,
1620 earliest, target, false, true);
1621 if (! cond || ! reg_mentioned_p (target, cond))
1624 /* We almost certainly searched back to a different place.
1625 Need to re-verify correct lifetimes. */
1627 /* X may not be mentioned in the range (cond_earliest, jump]. */
1628 for (insn = if_info->jump; insn != *earliest; insn = PREV_INSN (insn))
1629 if (INSN_P (insn) && reg_overlap_mentioned_p (if_info->x, PATTERN (insn)))
1632 /* A and B may not be modified in the range [cond_earliest, jump). */
1633 for (insn = *earliest; insn != if_info->jump; insn = NEXT_INSN (insn))
1635 && (modified_in_p (if_info->a, insn)
1636 || modified_in_p (if_info->b, insn)))
1642 /* Convert "if (a < b) x = a; else x = b;" to "x = min(a, b);", etc. */
1645 noce_try_minmax (struct noce_if_info *if_info)
1647 rtx cond, earliest, target, seq;
1648 enum rtx_code code, op;
1651 /* ??? Can't guarantee that expand_binop won't create pseudos. */
1655 /* ??? Reject modes with NaNs or signed zeros since we don't know how
1656 they will be resolved with an SMIN/SMAX. It wouldn't be too hard
1657 to get the target to tell us... */
1658 if (HONOR_SIGNED_ZEROS (GET_MODE (if_info->x))
1659 || HONOR_NANS (GET_MODE (if_info->x)))
1662 cond = noce_get_alt_condition (if_info, if_info->a, &earliest);
1666 /* Verify the condition is of the form we expect, and canonicalize
1667 the comparison code. */
1668 code = GET_CODE (cond);
1669 if (rtx_equal_p (XEXP (cond, 0), if_info->a))
1671 if (! rtx_equal_p (XEXP (cond, 1), if_info->b))
1674 else if (rtx_equal_p (XEXP (cond, 1), if_info->a))
1676 if (! rtx_equal_p (XEXP (cond, 0), if_info->b))
1678 code = swap_condition (code);
1683 /* Determine what sort of operation this is. Note that the code is for
1684 a taken branch, so the code->operation mapping appears backwards. */
1717 target = expand_simple_binop (GET_MODE (if_info->x), op,
1718 if_info->a, if_info->b,
1719 if_info->x, unsignedp, OPTAB_WIDEN);
1725 if (target != if_info->x)
1726 noce_emit_move_insn (if_info->x, target);
1728 seq = end_ifcvt_sequence (if_info);
1732 emit_insn_before_setloc (seq, if_info->jump, INSN_LOCATOR (if_info->insn_a));
1733 if_info->cond = cond;
1734 if_info->cond_earliest = earliest;
1739 /* Convert "if (a < 0) x = -a; else x = a;" to "x = abs(a);", etc. */
1742 noce_try_abs (struct noce_if_info *if_info)
1744 rtx cond, earliest, target, seq, a, b, c;
1747 /* ??? Can't guarantee that expand_binop won't create pseudos. */
1751 /* Recognize A and B as constituting an ABS or NABS. The canonical
1752 form is a branch around the negation, taken when the object is the
1753 first operand of a comparison against 0 that evaluates to true. */
1756 if (GET_CODE (a) == NEG && rtx_equal_p (XEXP (a, 0), b))
1758 else if (GET_CODE (b) == NEG && rtx_equal_p (XEXP (b, 0), a))
1760 c = a; a = b; b = c;
1766 cond = noce_get_alt_condition (if_info, b, &earliest);
1770 /* Verify the condition is of the form we expect. */
1771 if (rtx_equal_p (XEXP (cond, 0), b))
1773 else if (rtx_equal_p (XEXP (cond, 1), b))
1781 /* Verify that C is zero. Search one step backward for a
1782 REG_EQUAL note or a simple source if necessary. */
1785 rtx set, insn = prev_nonnote_insn (earliest);
1787 && (set = single_set (insn))
1788 && rtx_equal_p (SET_DEST (set), c))
1790 rtx note = find_reg_equal_equiv_note (insn);
1800 && GET_CODE (XEXP (c, 0)) == SYMBOL_REF
1801 && CONSTANT_POOL_ADDRESS_P (XEXP (c, 0)))
1802 c = get_pool_constant (XEXP (c, 0));
1804 /* Work around funny ideas get_condition has wrt canonicalization.
1805 Note that these rtx constants are known to be CONST_INT, and
1806 therefore imply integer comparisons. */
1807 if (c == constm1_rtx && GET_CODE (cond) == GT)
1809 else if (c == const1_rtx && GET_CODE (cond) == LT)
1811 else if (c != CONST0_RTX (GET_MODE (b)))
1814 /* Determine what sort of operation this is. */
1815 switch (GET_CODE (cond))
1834 target = expand_abs_nojump (GET_MODE (if_info->x), b, if_info->x, 1);
1836 /* ??? It's a quandary whether cmove would be better here, especially
1837 for integers. Perhaps combine will clean things up. */
1838 if (target && negate)
1839 target = expand_simple_unop (GET_MODE (target), NEG, target, if_info->x, 0);
1847 if (target != if_info->x)
1848 noce_emit_move_insn (if_info->x, target);
1850 seq = end_ifcvt_sequence (if_info);
1854 emit_insn_before_setloc (seq, if_info->jump, INSN_LOCATOR (if_info->insn_a));
1855 if_info->cond = cond;
1856 if_info->cond_earliest = earliest;
1861 /* Convert "if (m < 0) x = b; else x = 0;" to "x = (m >> C) & b;". */
1864 noce_try_sign_mask (struct noce_if_info *if_info)
1866 rtx cond, t, m, c, seq;
1867 enum machine_mode mode;
1873 cond = if_info->cond;
1874 code = GET_CODE (cond);
1879 if (if_info->a == const0_rtx)
1881 if ((code == LT && c == const0_rtx)
1882 || (code == LE && c == constm1_rtx))
1885 else if (if_info->b == const0_rtx)
1887 if ((code == GE && c == const0_rtx)
1888 || (code == GT && c == constm1_rtx))
1892 if (! t || side_effects_p (t))
1895 /* We currently don't handle different modes. */
1896 mode = GET_MODE (t);
1897 if (GET_MODE (m) != mode)
1900 /* This is only profitable if T is cheap, or T is unconditionally
1901 executed/evaluated in the original insn sequence. The latter
1902 happens if INSN_B was taken from TEST_BB. */
1903 if (rtx_cost (t, SET) >= COSTS_N_INSNS (2)
1904 && (BLOCK_FOR_INSN (if_info->insn_b) != if_info->test_bb
1905 || t != if_info->b))
1909 /* Use emit_store_flag to generate "m < 0 ? -1 : 0" instead of expanding
1910 "(signed) m >> 31" directly. This benefits targets with specialized
1911 insns to obtain the signmask, but still uses ashr_optab otherwise. */
1912 m = emit_store_flag (gen_reg_rtx (mode), LT, m, const0_rtx, mode, 0, -1);
1913 t = m ? expand_binop (mode, and_optab, m, t, NULL_RTX, 0, OPTAB_DIRECT)
1922 noce_emit_move_insn (if_info->x, t);
1924 seq = end_ifcvt_sequence (if_info);
1928 emit_insn_before_setloc (seq, if_info->jump, INSN_LOCATOR (if_info->insn_a));
1933 /* Optimize away "if (x & C) x |= C" and similar bit manipulation
1937 noce_try_bitop (struct noce_if_info *if_info)
1939 rtx cond, x, a, result, seq;
1940 enum machine_mode mode;
1945 cond = if_info->cond;
1946 code = GET_CODE (cond);
1948 /* Check for no else condition. */
1949 if (! rtx_equal_p (x, if_info->b))
1952 /* Check for a suitable condition. */
1953 if (code != NE && code != EQ)
1955 if (XEXP (cond, 1) != const0_rtx)
1957 cond = XEXP (cond, 0);
1959 /* ??? We could also handle AND here. */
1960 if (GET_CODE (cond) == ZERO_EXTRACT)
1962 if (XEXP (cond, 1) != const1_rtx
1963 || GET_CODE (XEXP (cond, 2)) != CONST_INT
1964 || ! rtx_equal_p (x, XEXP (cond, 0)))
1966 bitnum = INTVAL (XEXP (cond, 2));
1967 mode = GET_MODE (x);
1968 if (BITS_BIG_ENDIAN)
1969 bitnum = GET_MODE_BITSIZE (mode) - 1 - bitnum;
1970 if (bitnum < 0 || bitnum >= HOST_BITS_PER_WIDE_INT)
1977 if (GET_CODE (a) == IOR || GET_CODE (a) == XOR)
1979 /* Check for "if (X & C) x = x op C". */
1980 if (! rtx_equal_p (x, XEXP (a, 0))
1981 || GET_CODE (XEXP (a, 1)) != CONST_INT
1982 || (INTVAL (XEXP (a, 1)) & GET_MODE_MASK (mode))
1983 != (unsigned HOST_WIDE_INT) 1 << bitnum)
1986 /* if ((x & C) == 0) x |= C; is transformed to x |= C. */
1987 /* if ((x & C) != 0) x |= C; is transformed to nothing. */
1988 if (GET_CODE (a) == IOR)
1989 result = (code == NE) ? a : NULL_RTX;
1990 else if (code == NE)
1992 /* if ((x & C) == 0) x ^= C; is transformed to x |= C. */
1993 result = gen_int_mode ((HOST_WIDE_INT) 1 << bitnum, mode);
1994 result = simplify_gen_binary (IOR, mode, x, result);
1998 /* if ((x & C) != 0) x ^= C; is transformed to x &= ~C. */
1999 result = gen_int_mode (~((HOST_WIDE_INT) 1 << bitnum), mode);
2000 result = simplify_gen_binary (AND, mode, x, result);
2003 else if (GET_CODE (a) == AND)
2005 /* Check for "if (X & C) x &= ~C". */
2006 if (! rtx_equal_p (x, XEXP (a, 0))
2007 || GET_CODE (XEXP (a, 1)) != CONST_INT
2008 || (INTVAL (XEXP (a, 1)) & GET_MODE_MASK (mode))
2009 != (~((HOST_WIDE_INT) 1 << bitnum) & GET_MODE_MASK (mode)))
2012 /* if ((x & C) == 0) x &= ~C; is transformed to nothing. */
2013 /* if ((x & C) != 0) x &= ~C; is transformed to x &= ~C. */
2014 result = (code == EQ) ? a : NULL_RTX;
2022 noce_emit_move_insn (x, result);
2023 seq = end_ifcvt_sequence (if_info);
2027 emit_insn_before_setloc (seq, if_info->jump,
2028 INSN_LOCATOR (if_info->insn_a));
2034 /* Similar to get_condition, only the resulting condition must be
2035 valid at JUMP, instead of at EARLIEST. */
2038 noce_get_condition (rtx jump, rtx *earliest)
2043 if (! any_condjump_p (jump))
2046 set = pc_set (jump);
2048 /* If this branches to JUMP_LABEL when the condition is false,
2049 reverse the condition. */
2050 reverse = (GET_CODE (XEXP (SET_SRC (set), 2)) == LABEL_REF
2051 && XEXP (XEXP (SET_SRC (set), 2), 0) == JUMP_LABEL (jump));
2053 /* If the condition variable is a register and is MODE_INT, accept it. */
2055 cond = XEXP (SET_SRC (set), 0);
2056 tmp = XEXP (cond, 0);
2057 if (REG_P (tmp) && GET_MODE_CLASS (GET_MODE (tmp)) == MODE_INT)
2062 cond = gen_rtx_fmt_ee (reverse_condition (GET_CODE (cond)),
2063 GET_MODE (cond), tmp, XEXP (cond, 1));
2067 /* Otherwise, fall back on canonicalize_condition to do the dirty
2068 work of manipulating MODE_CC values and COMPARE rtx codes. */
2069 return canonicalize_condition (jump, cond, reverse, earliest,
2070 NULL_RTX, false, true);
2073 /* Initialize for a simple IF-THEN or IF-THEN-ELSE block. We will not
2074 be using conditional execution. Set some fields of IF_INFO based
2075 on CE_INFO: test_bb, cond, jump, cond_earliest. Return TRUE if
2079 noce_init_if_info (struct ce_if_block *ce_info, struct noce_if_info *if_info)
2081 basic_block test_bb = ce_info->test_bb;
2084 /* If test is comprised of && or || elements, don't handle it unless
2085 it is the special case of && elements without an ELSE block. */
2086 if (ce_info->num_multiple_test_blocks)
2088 if (ce_info->else_bb || !ce_info->and_and_p)
2091 ce_info->test_bb = test_bb = ce_info->last_test_bb;
2092 ce_info->num_multiple_test_blocks = 0;
2093 ce_info->num_and_and_blocks = 0;
2094 ce_info->num_or_or_blocks = 0;
2097 /* If this is not a standard conditional jump, we can't parse it. */
2098 jump = BB_END (test_bb);
2099 cond = noce_get_condition (jump, &if_info->cond_earliest);
2103 /* If the conditional jump is more than just a conditional
2104 jump, then we can not do if-conversion on this block. */
2105 if (! onlyjump_p (jump))
2108 /* We must be comparing objects whose modes imply the size. */
2109 if (GET_MODE (XEXP (cond, 0)) == BLKmode)
2112 if_info->test_bb = test_bb;
2113 if_info->cond = cond;
2114 if_info->jump = jump;
2119 /* Return true if OP is ok for if-then-else processing. */
2122 noce_operand_ok (rtx op)
2124 /* We special-case memories, so handle any of them with
2125 no address side effects. */
2127 return ! side_effects_p (XEXP (op, 0));
2129 if (side_effects_p (op))
2132 return ! may_trap_p (op);
2135 /* Return true if a write into MEM may trap or fault. */
2138 noce_mem_write_may_trap_or_fault_p (rtx mem)
2142 if (MEM_READONLY_P (mem))
2145 if (may_trap_or_fault_p (mem))
2148 addr = XEXP (mem, 0);
2150 /* Call target hook to avoid the effects of -fpic etc.... */
2151 addr = targetm.delegitimize_address (addr);
2154 switch (GET_CODE (addr))
2162 addr = XEXP (addr, 0);
2166 addr = XEXP (addr, 1);
2169 if (GET_CODE (XEXP (addr, 1)) == CONST_INT)
2170 addr = XEXP (addr, 0);
2177 if (SYMBOL_REF_DECL (addr)
2178 && decl_readonly_section (SYMBOL_REF_DECL (addr), 0))
2188 /* Given a simple IF-THEN or IF-THEN-ELSE block, attempt to convert it
2189 without using conditional execution. Return TRUE if we were
2190 successful at converting the block. */
2193 noce_process_if_block (struct ce_if_block * ce_info)
2195 basic_block test_bb = ce_info->test_bb; /* test block */
2196 basic_block then_bb = ce_info->then_bb; /* THEN */
2197 basic_block else_bb = ce_info->else_bb; /* ELSE or NULL */
2198 basic_block join_bb;
2199 struct noce_if_info if_info;
2202 rtx orig_x, x, a, b;
2205 /* We're looking for patterns of the form
2207 (1) if (...) x = a; else x = b;
2208 (2) x = b; if (...) x = a;
2209 (3) if (...) x = a; // as if with an initial x = x.
2211 The later patterns require jumps to be more expensive.
2213 ??? For future expansion, look for multiple X in such patterns. */
2215 if (!noce_init_if_info (ce_info, &if_info))
2218 cond = if_info.cond;
2219 jump = if_info.jump;
2221 /* Look for one of the potential sets. */
2222 insn_a = first_active_insn (then_bb);
2224 || insn_a != last_active_insn (then_bb, FALSE)
2225 || (set_a = single_set (insn_a)) == NULL_RTX)
2228 x = SET_DEST (set_a);
2229 a = SET_SRC (set_a);
2231 /* Look for the other potential set. Make sure we've got equivalent
2233 /* ??? This is overconservative. Storing to two different mems is
2234 as easy as conditionally computing the address. Storing to a
2235 single mem merely requires a scratch memory to use as one of the
2236 destination addresses; often the memory immediately below the
2237 stack pointer is available for this. */
2241 insn_b = first_active_insn (else_bb);
2243 || insn_b != last_active_insn (else_bb, FALSE)
2244 || (set_b = single_set (insn_b)) == NULL_RTX
2245 || ! rtx_equal_p (x, SET_DEST (set_b)))
2250 insn_b = prev_nonnote_insn (if_info.cond_earliest);
2251 /* We're going to be moving the evaluation of B down from above
2252 COND_EARLIEST to JUMP. Make sure the relevant data is still
2255 || !NONJUMP_INSN_P (insn_b)
2256 || (set_b = single_set (insn_b)) == NULL_RTX
2257 || ! rtx_equal_p (x, SET_DEST (set_b))
2258 || reg_overlap_mentioned_p (x, SET_SRC (set_b))
2259 || modified_between_p (SET_SRC (set_b),
2260 PREV_INSN (if_info.cond_earliest), jump)
2261 /* Likewise with X. In particular this can happen when
2262 noce_get_condition looks farther back in the instruction
2263 stream than one might expect. */
2264 || reg_overlap_mentioned_p (x, cond)
2265 || reg_overlap_mentioned_p (x, a)
2266 || modified_between_p (x, PREV_INSN (if_info.cond_earliest), jump))
2267 insn_b = set_b = NULL_RTX;
2270 /* If x has side effects then only the if-then-else form is safe to
2271 convert. But even in that case we would need to restore any notes
2272 (such as REG_INC) at then end. That can be tricky if
2273 noce_emit_move_insn expands to more than one insn, so disable the
2274 optimization entirely for now if there are side effects. */
2275 if (side_effects_p (x))
2278 b = (set_b ? SET_SRC (set_b) : x);
2280 /* Only operate on register destinations, and even then avoid extending
2281 the lifetime of hard registers on small register class machines. */
2284 || (SMALL_REGISTER_CLASSES
2285 && REGNO (x) < FIRST_PSEUDO_REGISTER))
2287 if (no_new_pseudos || GET_MODE (x) == BLKmode)
2290 if (GET_MODE (x) == ZERO_EXTRACT
2291 && (GET_CODE (XEXP (x, 1)) != CONST_INT
2292 || GET_CODE (XEXP (x, 2)) != CONST_INT))
2295 x = gen_reg_rtx (GET_MODE (GET_CODE (x) == STRICT_LOW_PART
2296 ? XEXP (x, 0) : x));
2299 /* Don't operate on sources that may trap or are volatile. */
2300 if (! noce_operand_ok (a) || ! noce_operand_ok (b))
2303 /* Set up the info block for our subroutines. */
2304 if_info.insn_a = insn_a;
2305 if_info.insn_b = insn_b;
2310 /* Try optimizations in some approximation of a useful order. */
2311 /* ??? Should first look to see if X is live incoming at all. If it
2312 isn't, we don't need anything but an unconditional set. */
2314 /* Look and see if A and B are really the same. Avoid creating silly
2315 cmove constructs that no one will fix up later. */
2316 if (rtx_equal_p (a, b))
2318 /* If we have an INSN_B, we don't have to create any new rtl. Just
2319 move the instruction that we already have. If we don't have an
2320 INSN_B, that means that A == X, and we've got a noop move. In
2321 that case don't do anything and let the code below delete INSN_A. */
2322 if (insn_b && else_bb)
2326 if (else_bb && insn_b == BB_END (else_bb))
2327 BB_END (else_bb) = PREV_INSN (insn_b);
2328 reorder_insns (insn_b, insn_b, PREV_INSN (jump));
2330 /* If there was a REG_EQUAL note, delete it since it may have been
2331 true due to this insn being after a jump. */
2332 if ((note = find_reg_note (insn_b, REG_EQUAL, NULL_RTX)) != 0)
2333 remove_note (insn_b, note);
2337 /* If we have "x = b; if (...) x = a;", and x has side-effects, then
2338 x must be executed twice. */
2339 else if (insn_b && side_effects_p (orig_x))
2346 /* Disallow the "if (...) x = a;" form (with an implicit "else x = x;")
2347 for optimizations if writing to x may trap or fault, i.e. it's a memory
2348 other than a static var or a stack slot, is misaligned on strict
2349 aligned machines or is read-only.
2350 If x is a read-only memory, then the program is valid only if we
2351 avoid the store into it. If there are stores on both the THEN and
2352 ELSE arms, then we can go ahead with the conversion; either the
2353 program is broken, or the condition is always false such that the
2354 other memory is selected. */
2355 if (!set_b && MEM_P (orig_x) && noce_mem_write_may_trap_or_fault_p (orig_x))
2358 if (noce_try_move (&if_info))
2360 if (noce_try_store_flag (&if_info))
2362 if (noce_try_bitop (&if_info))
2364 if (noce_try_minmax (&if_info))
2366 if (noce_try_abs (&if_info))
2368 if (HAVE_conditional_move
2369 && noce_try_cmove (&if_info))
2371 if (! HAVE_conditional_execution)
2373 if (noce_try_store_flag_constants (&if_info))
2375 if (noce_try_addcc (&if_info))
2377 if (noce_try_store_flag_mask (&if_info))
2379 if (HAVE_conditional_move
2380 && noce_try_cmove_arith (&if_info))
2382 if (noce_try_sign_mask (&if_info))
2390 /* If we used a temporary, fix it up now. */
2396 noce_emit_move_insn (orig_x, x);
2398 set_used_flags (orig_x);
2399 unshare_all_rtl_in_chain (seq);
2402 emit_insn_before_setloc (seq, BB_END (test_bb), INSN_LOCATOR (insn_a));
2405 /* The original THEN and ELSE blocks may now be removed. The test block
2406 must now jump to the join block. If the test block and the join block
2407 can be merged, do so. */
2409 join_bb = single_succ (then_bb);
2412 delete_basic_block (else_bb);
2416 remove_edge (find_edge (test_bb, join_bb));
2418 remove_edge (find_edge (then_bb, join_bb));
2419 redirect_edge_and_branch_force (single_succ_edge (test_bb), join_bb);
2420 delete_basic_block (then_bb);
2423 if (can_merge_blocks_p (test_bb, join_bb))
2425 merge_blocks (test_bb, join_bb);
2429 num_updated_if_blocks++;
2433 /* Check whether a block is suitable for conditional move conversion.
2434 Every insn must be a simple set of a register to a constant or a
2435 register. For each assignment, store the value in the array VALS,
2436 indexed by register number, then store the register number in
2437 REGS. COND is the condition we will test. */
2440 check_cond_move_block (basic_block bb, rtx *vals, VEC (int, heap) *regs, rtx cond)
2444 /* We can only handle simple jumps at the end of the basic block.
2445 It is almost impossible to update the CFG otherwise. */
2447 if (JUMP_P (insn) && !onlyjump_p (insn))
2450 FOR_BB_INSNS (bb, insn)
2454 if (!INSN_P (insn) || JUMP_P (insn))
2456 set = single_set (insn);
2460 dest = SET_DEST (set);
2461 src = SET_SRC (set);
2463 || (SMALL_REGISTER_CLASSES && HARD_REGISTER_P (dest)))
2466 if (!CONSTANT_P (src) && !register_operand (src, VOIDmode))
2469 if (side_effects_p (src) || side_effects_p (dest))
2472 if (may_trap_p (src) || may_trap_p (dest))
2475 /* Don't try to handle this if the source register was
2476 modified earlier in the block. */
2478 && vals[REGNO (src)] != NULL)
2479 || (GET_CODE (src) == SUBREG && REG_P (SUBREG_REG (src))
2480 && vals[REGNO (SUBREG_REG (src))] != NULL))
2483 /* Don't try to handle this if the destination register was
2484 modified earlier in the block. */
2485 if (vals[REGNO (dest)] != NULL)
2488 /* Don't try to handle this if the condition uses the
2489 destination register. */
2490 if (reg_overlap_mentioned_p (dest, cond))
2493 /* Don't try to handle this if the source register is modified
2494 later in the block. */
2495 if (!CONSTANT_P (src)
2496 && modified_between_p (src, insn, NEXT_INSN (BB_END (bb))))
2499 vals[REGNO (dest)] = src;
2501 VEC_safe_push (int, heap, regs, REGNO (dest));
2507 /* Given a basic block BB suitable for conditional move conversion,
2508 a condition COND, and arrays THEN_VALS and ELSE_VALS containing the
2509 register values depending on COND, emit the insns in the block as
2510 conditional moves. If ELSE_BLOCK is true, THEN_BB was already
2511 processed. The caller has started a sequence for the conversion.
2512 Return true if successful, false if something goes wrong. */
2515 cond_move_convert_if_block (struct noce_if_info *if_infop,
2516 basic_block bb, rtx cond,
2517 rtx *then_vals, rtx *else_vals,
2521 rtx insn, cond_arg0, cond_arg1;
2523 code = GET_CODE (cond);
2524 cond_arg0 = XEXP (cond, 0);
2525 cond_arg1 = XEXP (cond, 1);
2527 FOR_BB_INSNS (bb, insn)
2529 rtx set, target, dest, t, e;
2532 if (!INSN_P (insn) || JUMP_P (insn))
2534 set = single_set (insn);
2535 gcc_assert (set && REG_P (SET_DEST (set)));
2537 dest = SET_DEST (set);
2538 regno = REGNO (dest);
2540 t = then_vals[regno];
2541 e = else_vals[regno];
2545 /* If this register was set in the then block, we already
2546 handled this case there. */
2559 target = noce_emit_cmove (if_infop, dest, code, cond_arg0, cond_arg1,
2565 noce_emit_move_insn (dest, target);
2571 /* Given a simple IF-THEN or IF-THEN-ELSE block, attempt to convert it
2572 using only conditional moves. Return TRUE if we were successful at
2573 converting the block. */
2576 cond_move_process_if_block (struct ce_if_block *ce_info)
2578 basic_block test_bb = ce_info->test_bb;
2579 basic_block then_bb = ce_info->then_bb;
2580 basic_block else_bb = ce_info->else_bb;
2581 basic_block join_bb;
2582 struct noce_if_info if_info;
2583 rtx jump, cond, seq, loc_insn;
2584 int max_reg, size, c, reg;
2587 VEC (int, heap) *then_regs = NULL;
2588 VEC (int, heap) *else_regs = NULL;
2591 if (!HAVE_conditional_move || no_new_pseudos)
2594 memset (&if_info, 0, sizeof if_info);
2596 if (!noce_init_if_info (ce_info, &if_info))
2599 cond = if_info.cond;
2600 jump = if_info.jump;
2602 /* Build a mapping for each block to the value used for each
2604 max_reg = max_reg_num ();
2605 size = (max_reg + 1) * sizeof (rtx);
2606 then_vals = (rtx *) alloca (size);
2607 else_vals = (rtx *) alloca (size);
2608 memset (then_vals, 0, size);
2609 memset (else_vals, 0, size);
2611 /* Make sure the blocks are suitable. */
2612 if (!check_cond_move_block (then_bb, then_vals, then_regs, cond)
2613 || (else_bb && !check_cond_move_block (else_bb, else_vals, else_regs, cond)))
2616 /* Make sure the blocks can be used together. If the same register
2617 is set in both blocks, and is not set to a constant in both
2618 cases, then both blocks must set it to the same register. We
2619 have already verified that if it is set to a register, that the
2620 source register does not change after the assignment. Also count
2621 the number of registers set in only one of the blocks. */
2623 for (i = 0; VEC_iterate (int, then_regs, i, reg); i++)
2625 if (!then_vals[reg] && !else_vals[reg])
2628 if (!else_vals[reg])
2632 if (!CONSTANT_P (then_vals[reg])
2633 && !CONSTANT_P (else_vals[reg])
2634 && !rtx_equal_p (then_vals[reg], else_vals[reg]))
2639 /* Finish off c for MAX_CONDITIONAL_EXECUTE. */
2640 for (i = 0; VEC_iterate (int, else_regs, i, reg); ++i)
2641 if (!then_vals[reg])
2644 /* Make sure it is reasonable to convert this block. What matters
2645 is the number of assignments currently made in only one of the
2646 branches, since if we convert we are going to always execute
2648 if (c > MAX_CONDITIONAL_EXECUTE)
2651 /* Try to emit the conditional moves. First do the then block,
2652 then do anything left in the else blocks. */
2654 if (!cond_move_convert_if_block (&if_info, then_bb, cond,
2655 then_vals, else_vals, false)
2657 && !cond_move_convert_if_block (&if_info, else_bb, cond,
2658 then_vals, else_vals, true)))
2663 seq = end_ifcvt_sequence (&if_info);
2667 loc_insn = first_active_insn (then_bb);
2670 loc_insn = first_active_insn (else_bb);
2671 gcc_assert (loc_insn);
2673 emit_insn_before_setloc (seq, jump, INSN_LOCATOR (loc_insn));
2675 join_bb = single_succ (then_bb);
2678 delete_basic_block (else_bb);
2682 remove_edge (find_edge (test_bb, join_bb));
2684 remove_edge (find_edge (then_bb, join_bb));
2685 redirect_edge_and_branch_force (single_succ_edge (test_bb), join_bb);
2686 delete_basic_block (then_bb);
2689 if (can_merge_blocks_p (test_bb, join_bb))
2691 merge_blocks (test_bb, join_bb);
2695 num_updated_if_blocks++;
2697 VEC_free (int, heap, then_regs);
2698 VEC_free (int, heap, else_regs);
2704 /* Attempt to convert an IF-THEN or IF-THEN-ELSE block into
2705 straight line code. Return true if successful. */
2708 process_if_block (struct ce_if_block * ce_info)
2710 if (! reload_completed
2711 && noce_process_if_block (ce_info))
2714 if (HAVE_conditional_move
2715 && cond_move_process_if_block (ce_info))
2718 if (HAVE_conditional_execution && reload_completed)
2720 /* If we have && and || tests, try to first handle combining the && and
2721 || tests into the conditional code, and if that fails, go back and
2722 handle it without the && and ||, which at present handles the && case
2723 if there was no ELSE block. */
2724 if (cond_exec_process_if_block (ce_info, TRUE))
2727 if (ce_info->num_multiple_test_blocks)
2731 if (cond_exec_process_if_block (ce_info, FALSE))
2739 /* Merge the blocks and mark for local life update. */
2742 merge_if_block (struct ce_if_block * ce_info)
2744 basic_block test_bb = ce_info->test_bb; /* last test block */
2745 basic_block then_bb = ce_info->then_bb; /* THEN */
2746 basic_block else_bb = ce_info->else_bb; /* ELSE or NULL */
2747 basic_block join_bb = ce_info->join_bb; /* join block */
2748 basic_block combo_bb;
2750 /* All block merging is done into the lower block numbers. */
2754 /* Merge any basic blocks to handle && and || subtests. Each of
2755 the blocks are on the fallthru path from the predecessor block. */
2756 if (ce_info->num_multiple_test_blocks > 0)
2758 basic_block bb = test_bb;
2759 basic_block last_test_bb = ce_info->last_test_bb;
2760 basic_block fallthru = block_fallthru (bb);
2765 fallthru = block_fallthru (bb);
2766 merge_blocks (combo_bb, bb);
2769 while (bb != last_test_bb);
2772 /* Merge TEST block into THEN block. Normally the THEN block won't have a
2773 label, but it might if there were || tests. That label's count should be
2774 zero, and it normally should be removed. */
2778 merge_blocks (combo_bb, then_bb);
2782 /* The ELSE block, if it existed, had a label. That label count
2783 will almost always be zero, but odd things can happen when labels
2784 get their addresses taken. */
2787 merge_blocks (combo_bb, else_bb);
2791 /* If there was no join block reported, that means it was not adjacent
2792 to the others, and so we cannot merge them. */
2796 rtx last = BB_END (combo_bb);
2798 /* The outgoing edge for the current COMBO block should already
2799 be correct. Verify this. */
2800 if (EDGE_COUNT (combo_bb->succs) == 0)
2801 gcc_assert (find_reg_note (last, REG_NORETURN, NULL)
2802 || (NONJUMP_INSN_P (last)
2803 && GET_CODE (PATTERN (last)) == TRAP_IF
2804 && (TRAP_CONDITION (PATTERN (last))
2805 == const_true_rtx)));
2808 /* There should still be something at the end of the THEN or ELSE
2809 blocks taking us to our final destination. */
2810 gcc_assert (JUMP_P (last)
2811 || (EDGE_SUCC (combo_bb, 0)->dest == EXIT_BLOCK_PTR
2813 && SIBLING_CALL_P (last))
2814 || ((EDGE_SUCC (combo_bb, 0)->flags & EDGE_EH)
2815 && can_throw_internal (last)));
2818 /* The JOIN block may have had quite a number of other predecessors too.
2819 Since we've already merged the TEST, THEN and ELSE blocks, we should
2820 have only one remaining edge from our if-then-else diamond. If there
2821 is more than one remaining edge, it must come from elsewhere. There
2822 may be zero incoming edges if the THEN block didn't actually join
2823 back up (as with a call to a non-return function). */
2824 else if (EDGE_COUNT (join_bb->preds) < 2
2825 && join_bb != EXIT_BLOCK_PTR)
2827 /* We can merge the JOIN. */
2828 merge_blocks (combo_bb, join_bb);
2833 /* We cannot merge the JOIN. */
2835 /* The outgoing edge for the current COMBO block should already
2836 be correct. Verify this. */
2837 gcc_assert (single_succ_p (combo_bb)
2838 && single_succ (combo_bb) == join_bb);
2840 /* Remove the jump and cruft from the end of the COMBO block. */
2841 if (join_bb != EXIT_BLOCK_PTR)
2842 tidy_fallthru_edge (single_succ_edge (combo_bb));
2845 num_updated_if_blocks++;
2848 /* Find a block ending in a simple IF condition and try to transform it
2849 in some way. When converting a multi-block condition, put the new code
2850 in the first such block and delete the rest. Return a pointer to this
2851 first block if some transformation was done. Return NULL otherwise. */
2854 find_if_header (basic_block test_bb, int pass)
2856 ce_if_block_t ce_info;
2860 /* The kind of block we're looking for has exactly two successors. */
2861 if (EDGE_COUNT (test_bb->succs) != 2)
2864 then_edge = EDGE_SUCC (test_bb, 0);
2865 else_edge = EDGE_SUCC (test_bb, 1);
2867 /* Neither edge should be abnormal. */
2868 if ((then_edge->flags & EDGE_COMPLEX)
2869 || (else_edge->flags & EDGE_COMPLEX))
2872 /* Nor exit the loop. */
2873 if ((then_edge->flags & EDGE_LOOP_EXIT)
2874 || (else_edge->flags & EDGE_LOOP_EXIT))
2877 /* The THEN edge is canonically the one that falls through. */
2878 if (then_edge->flags & EDGE_FALLTHRU)
2880 else if (else_edge->flags & EDGE_FALLTHRU)
2883 else_edge = then_edge;
2887 /* Otherwise this must be a multiway branch of some sort. */
2890 memset (&ce_info, '\0', sizeof (ce_info));
2891 ce_info.test_bb = test_bb;
2892 ce_info.then_bb = then_edge->dest;
2893 ce_info.else_bb = else_edge->dest;
2894 ce_info.pass = pass;
2896 #ifdef IFCVT_INIT_EXTRA_FIELDS
2897 IFCVT_INIT_EXTRA_FIELDS (&ce_info);
2900 if (find_if_block (&ce_info))
2903 if (HAVE_trap && HAVE_conditional_trap
2904 && find_cond_trap (test_bb, then_edge, else_edge))
2907 if (dom_computed[CDI_POST_DOMINATORS] >= DOM_NO_FAST_QUERY
2908 && (! HAVE_conditional_execution || reload_completed))
2910 if (find_if_case_1 (test_bb, then_edge, else_edge))
2912 if (find_if_case_2 (test_bb, then_edge, else_edge))
2920 fprintf (dump_file, "Conversion succeeded on pass %d.\n", pass);
2921 return ce_info.test_bb;
2924 /* Return true if a block has two edges, one of which falls through to the next
2925 block, and the other jumps to a specific block, so that we can tell if the
2926 block is part of an && test or an || test. Returns either -1 or the number
2927 of non-note, non-jump, non-USE/CLOBBER insns in the block. */
2930 block_jumps_and_fallthru_p (basic_block cur_bb, basic_block target_bb)
2933 int fallthru_p = FALSE;
2940 if (!cur_bb || !target_bb)
2943 /* If no edges, obviously it doesn't jump or fallthru. */
2944 if (EDGE_COUNT (cur_bb->succs) == 0)
2947 FOR_EACH_EDGE (cur_edge, ei, cur_bb->succs)
2949 if (cur_edge->flags & EDGE_COMPLEX)
2950 /* Anything complex isn't what we want. */
2953 else if (cur_edge->flags & EDGE_FALLTHRU)
2956 else if (cur_edge->dest == target_bb)
2963 if ((jump_p & fallthru_p) == 0)
2966 /* Don't allow calls in the block, since this is used to group && and ||
2967 together for conditional execution support. ??? we should support
2968 conditional execution support across calls for IA-64 some day, but
2969 for now it makes the code simpler. */
2970 end = BB_END (cur_bb);
2971 insn = BB_HEAD (cur_bb);
2973 while (insn != NULL_RTX)
2980 && GET_CODE (PATTERN (insn)) != USE
2981 && GET_CODE (PATTERN (insn)) != CLOBBER)
2987 insn = NEXT_INSN (insn);
2993 /* Determine if a given basic block heads a simple IF-THEN or IF-THEN-ELSE
2994 block. If so, we'll try to convert the insns to not require the branch.
2995 Return TRUE if we were successful at converting the block. */
2998 find_if_block (struct ce_if_block * ce_info)
3000 basic_block test_bb = ce_info->test_bb;
3001 basic_block then_bb = ce_info->then_bb;
3002 basic_block else_bb = ce_info->else_bb;
3003 basic_block join_bb = NULL_BLOCK;
3008 ce_info->last_test_bb = test_bb;
3010 /* Discover if any fall through predecessors of the current test basic block
3011 were && tests (which jump to the else block) or || tests (which jump to
3013 if (HAVE_conditional_execution && reload_completed
3014 && single_pred_p (test_bb)
3015 && single_pred_edge (test_bb)->flags == EDGE_FALLTHRU)
3017 basic_block bb = single_pred (test_bb);
3018 basic_block target_bb;
3019 int max_insns = MAX_CONDITIONAL_EXECUTE;
3022 /* Determine if the preceding block is an && or || block. */
3023 if ((n_insns = block_jumps_and_fallthru_p (bb, else_bb)) >= 0)
3025 ce_info->and_and_p = TRUE;
3026 target_bb = else_bb;
3028 else if ((n_insns = block_jumps_and_fallthru_p (bb, then_bb)) >= 0)
3030 ce_info->and_and_p = FALSE;
3031 target_bb = then_bb;
3034 target_bb = NULL_BLOCK;
3036 if (target_bb && n_insns <= max_insns)
3038 int total_insns = 0;
3041 ce_info->last_test_bb = test_bb;
3043 /* Found at least one && or || block, look for more. */
3046 ce_info->test_bb = test_bb = bb;
3047 total_insns += n_insns;
3050 if (!single_pred_p (bb))
3053 bb = single_pred (bb);
3054 n_insns = block_jumps_and_fallthru_p (bb, target_bb);
3056 while (n_insns >= 0 && (total_insns + n_insns) <= max_insns);
3058 ce_info->num_multiple_test_blocks = blocks;
3059 ce_info->num_multiple_test_insns = total_insns;
3061 if (ce_info->and_and_p)
3062 ce_info->num_and_and_blocks = blocks;
3064 ce_info->num_or_or_blocks = blocks;
3068 /* The THEN block of an IF-THEN combo must have exactly one predecessor,
3069 other than any || blocks which jump to the THEN block. */
3070 if ((EDGE_COUNT (then_bb->preds) - ce_info->num_or_or_blocks) != 1)
3073 /* The edges of the THEN and ELSE blocks cannot have complex edges. */
3074 FOR_EACH_EDGE (cur_edge, ei, then_bb->preds)
3076 if (cur_edge->flags & EDGE_COMPLEX)
3080 FOR_EACH_EDGE (cur_edge, ei, else_bb->preds)
3082 if (cur_edge->flags & EDGE_COMPLEX)
3086 /* The THEN block of an IF-THEN combo must have zero or one successors. */
3087 if (EDGE_COUNT (then_bb->succs) > 0
3088 && (!single_succ_p (then_bb)
3089 || (single_succ_edge (then_bb)->flags & EDGE_COMPLEX)
3090 || (flow2_completed && tablejump_p (BB_END (then_bb), NULL, NULL))))
3093 /* If the THEN block has no successors, conditional execution can still
3094 make a conditional call. Don't do this unless the ELSE block has
3095 only one incoming edge -- the CFG manipulation is too ugly otherwise.
3096 Check for the last insn of the THEN block being an indirect jump, which
3097 is listed as not having any successors, but confuses the rest of the CE
3098 code processing. ??? we should fix this in the future. */
3099 if (EDGE_COUNT (then_bb->succs) == 0)
3101 if (single_pred_p (else_bb))
3103 rtx last_insn = BB_END (then_bb);
3106 && NOTE_P (last_insn)
3107 && last_insn != BB_HEAD (then_bb))
3108 last_insn = PREV_INSN (last_insn);
3111 && JUMP_P (last_insn)
3112 && ! simplejump_p (last_insn))
3116 else_bb = NULL_BLOCK;
3122 /* If the THEN block's successor is the other edge out of the TEST block,
3123 then we have an IF-THEN combo without an ELSE. */
3124 else if (single_succ (then_bb) == else_bb)
3127 else_bb = NULL_BLOCK;
3130 /* If the THEN and ELSE block meet in a subsequent block, and the ELSE
3131 has exactly one predecessor and one successor, and the outgoing edge
3132 is not complex, then we have an IF-THEN-ELSE combo. */
3133 else if (single_succ_p (else_bb)
3134 && single_succ (then_bb) == single_succ (else_bb)
3135 && single_pred_p (else_bb)
3136 && ! (single_succ_edge (else_bb)->flags & EDGE_COMPLEX)
3137 && ! (flow2_completed && tablejump_p (BB_END (else_bb), NULL, NULL)))
3138 join_bb = single_succ (else_bb);
3140 /* Otherwise it is not an IF-THEN or IF-THEN-ELSE combination. */
3144 num_possible_if_blocks++;
3149 "\nIF-THEN%s block found, pass %d, start block %d "
3150 "[insn %d], then %d [%d]",
3151 (else_bb) ? "-ELSE" : "",
3154 BB_HEAD (test_bb) ? (int)INSN_UID (BB_HEAD (test_bb)) : -1,
3156 BB_HEAD (then_bb) ? (int)INSN_UID (BB_HEAD (then_bb)) : -1);
3159 fprintf (dump_file, ", else %d [%d]",
3161 BB_HEAD (else_bb) ? (int)INSN_UID (BB_HEAD (else_bb)) : -1);
3163 fprintf (dump_file, ", join %d [%d]",
3165 BB_HEAD (join_bb) ? (int)INSN_UID (BB_HEAD (join_bb)) : -1);
3167 if (ce_info->num_multiple_test_blocks > 0)
3168 fprintf (dump_file, ", %d %s block%s last test %d [%d]",
3169 ce_info->num_multiple_test_blocks,
3170 (ce_info->and_and_p) ? "&&" : "||",
3171 (ce_info->num_multiple_test_blocks == 1) ? "" : "s",
3172 ce_info->last_test_bb->index,
3173 ((BB_HEAD (ce_info->last_test_bb))
3174 ? (int)INSN_UID (BB_HEAD (ce_info->last_test_bb))
3177 fputc ('\n', dump_file);
3180 /* Make sure IF, THEN, and ELSE, blocks are adjacent. Actually, we get the
3181 first condition for free, since we've already asserted that there's a
3182 fallthru edge from IF to THEN. Likewise for the && and || blocks, since
3183 we checked the FALLTHRU flag, those are already adjacent to the last IF
3185 /* ??? As an enhancement, move the ELSE block. Have to deal with
3186 BLOCK notes, if by no other means than backing out the merge if they
3187 exist. Sticky enough I don't want to think about it now. */
3189 if (else_bb && (next = next->next_bb) != else_bb)
3191 if ((next = next->next_bb) != join_bb && join_bb != EXIT_BLOCK_PTR)
3199 /* Do the real work. */
3200 ce_info->else_bb = else_bb;
3201 ce_info->join_bb = join_bb;
3203 return process_if_block (ce_info);
3206 /* Convert a branch over a trap, or a branch
3207 to a trap, into a conditional trap. */
3210 find_cond_trap (basic_block test_bb, edge then_edge, edge else_edge)
3212 basic_block then_bb = then_edge->dest;
3213 basic_block else_bb = else_edge->dest;
3214 basic_block other_bb, trap_bb;
3215 rtx trap, jump, cond, cond_earliest, seq;
3218 /* Locate the block with the trap instruction. */
3219 /* ??? While we look for no successors, we really ought to allow
3220 EH successors. Need to fix merge_if_block for that to work. */
3221 if ((trap = block_has_only_trap (then_bb)) != NULL)
3222 trap_bb = then_bb, other_bb = else_bb;
3223 else if ((trap = block_has_only_trap (else_bb)) != NULL)
3224 trap_bb = else_bb, other_bb = then_bb;
3230 fprintf (dump_file, "\nTRAP-IF block found, start %d, trap %d\n",
3231 test_bb->index, trap_bb->index);
3234 /* If this is not a standard conditional jump, we can't parse it. */
3235 jump = BB_END (test_bb);
3236 cond = noce_get_condition (jump, &cond_earliest);
3240 /* If the conditional jump is more than just a conditional jump, then
3241 we can not do if-conversion on this block. */
3242 if (! onlyjump_p (jump))
3245 /* We must be comparing objects whose modes imply the size. */
3246 if (GET_MODE (XEXP (cond, 0)) == BLKmode)
3249 /* Reverse the comparison code, if necessary. */
3250 code = GET_CODE (cond);
3251 if (then_bb == trap_bb)
3253 code = reversed_comparison_code (cond, jump);
3254 if (code == UNKNOWN)
3258 /* Attempt to generate the conditional trap. */
3259 seq = gen_cond_trap (code, XEXP (cond, 0),
3261 TRAP_CODE (PATTERN (trap)));
3265 /* Emit the new insns before cond_earliest. */
3266 emit_insn_before_setloc (seq, cond_earliest, INSN_LOCATOR (trap));
3268 /* Delete the trap block if possible. */
3269 remove_edge (trap_bb == then_bb ? then_edge : else_edge);
3270 if (EDGE_COUNT (trap_bb->preds) == 0)
3272 delete_basic_block (trap_bb);
3276 /* Wire together the blocks again. */
3277 if (current_ir_type () == IR_RTL_CFGLAYOUT)
3278 single_succ_edge (test_bb)->flags |= EDGE_FALLTHRU;
3283 lab = JUMP_LABEL (jump);
3284 newjump = emit_jump_insn_after (gen_jump (lab), jump);
3285 LABEL_NUSES (lab) += 1;
3286 JUMP_LABEL (newjump) = lab;
3287 emit_barrier_after (newjump);
3291 if (can_merge_blocks_p (test_bb, other_bb))
3293 merge_blocks (test_bb, other_bb);
3297 num_updated_if_blocks++;
3301 /* Subroutine of find_cond_trap: if BB contains only a trap insn,
3305 block_has_only_trap (basic_block bb)
3309 /* We're not the exit block. */
3310 if (bb == EXIT_BLOCK_PTR)
3313 /* The block must have no successors. */
3314 if (EDGE_COUNT (bb->succs) > 0)
3317 /* The only instruction in the THEN block must be the trap. */
3318 trap = first_active_insn (bb);
3319 if (! (trap == BB_END (bb)
3320 && GET_CODE (PATTERN (trap)) == TRAP_IF
3321 && TRAP_CONDITION (PATTERN (trap)) == const_true_rtx))
3327 /* Look for IF-THEN-ELSE cases in which one of THEN or ELSE is
3328 transformable, but not necessarily the other. There need be no
3331 Return TRUE if we were successful at converting the block.
3333 Cases we'd like to look at:
3336 if (test) goto over; // x not live
3344 if (! test) goto label;
3347 if (test) goto E; // x not live
3361 (3) // This one's really only interesting for targets that can do
3362 // multiway branching, e.g. IA-64 BBB bundles. For other targets
3363 // it results in multiple branches on a cache line, which often
3364 // does not sit well with predictors.
3366 if (test1) goto E; // predicted not taken
3382 (A) Don't do (2) if the branch is predicted against the block we're
3383 eliminating. Do it anyway if we can eliminate a branch; this requires
3384 that the sole successor of the eliminated block postdominate the other
3387 (B) With CE, on (3) we can steal from both sides of the if, creating
3396 Again, this is most useful if J postdominates.
3398 (C) CE substitutes for helpful life information.
3400 (D) These heuristics need a lot of work. */
3402 /* Tests for case 1 above. */
3405 find_if_case_1 (basic_block test_bb, edge then_edge, edge else_edge)
3407 basic_block then_bb = then_edge->dest;
3408 basic_block else_bb = else_edge->dest, new_bb;
3411 /* If we are partitioning hot/cold basic blocks, we don't want to
3412 mess up unconditional or indirect jumps that cross between hot
3415 Basic block partitioning may result in some jumps that appear to
3416 be optimizable (or blocks that appear to be mergeable), but which really
3417 must be left untouched (they are required to make it safely across
3418 partition boundaries). See the comments at the top of
3419 bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */
3421 if ((BB_END (then_bb)
3422 && find_reg_note (BB_END (then_bb), REG_CROSSING_JUMP, NULL_RTX))
3423 || (BB_END (test_bb)
3424 && find_reg_note (BB_END (test_bb), REG_CROSSING_JUMP, NULL_RTX))
3425 || (BB_END (else_bb)
3426 && find_reg_note (BB_END (else_bb), REG_CROSSING_JUMP,
3430 /* THEN has one successor. */
3431 if (!single_succ_p (then_bb))
3434 /* THEN does not fall through, but is not strange either. */
3435 if (single_succ_edge (then_bb)->flags & (EDGE_COMPLEX | EDGE_FALLTHRU))
3438 /* THEN has one predecessor. */
3439 if (!single_pred_p (then_bb))
3442 /* THEN must do something. */
3443 if (forwarder_block_p (then_bb))
3446 num_possible_if_blocks++;
3449 "\nIF-CASE-1 found, start %d, then %d\n",
3450 test_bb->index, then_bb->index);
3452 /* THEN is small. */
3453 if (! cheap_bb_rtx_cost_p (then_bb, COSTS_N_INSNS (BRANCH_COST)))
3456 /* Registers set are dead, or are predicable. */
3457 if (! dead_or_predicable (test_bb, then_bb, else_bb,
3458 single_succ (then_bb), 1))
3461 /* Conversion went ok, including moving the insns and fixing up the
3462 jump. Adjust the CFG to match. */
3464 bitmap_ior (test_bb->il.rtl->global_live_at_end,
3465 else_bb->il.rtl->global_live_at_start,
3466 then_bb->il.rtl->global_live_at_end);
3469 /* We can avoid creating a new basic block if then_bb is immediately
3470 followed by else_bb, i.e. deleting then_bb allows test_bb to fall
3473 if (then_bb->next_bb == else_bb
3474 && then_bb->prev_bb == test_bb
3475 && else_bb != EXIT_BLOCK_PTR)
3477 redirect_edge_succ (FALLTHRU_EDGE (test_bb), else_bb);
3481 new_bb = redirect_edge_and_branch_force (FALLTHRU_EDGE (test_bb),
3484 then_bb_index = then_bb->index;
3485 delete_basic_block (then_bb);
3487 /* Make rest of code believe that the newly created block is the THEN_BB
3488 block we removed. */
3491 new_bb->index = then_bb_index;
3492 SET_BASIC_BLOCK (then_bb_index, new_bb);
3493 /* Since the fallthru edge was redirected from test_bb to new_bb,
3494 we need to ensure that new_bb is in the same partition as
3495 test bb (you can not fall through across section boundaries). */
3496 BB_COPY_PARTITION (new_bb, test_bb);
3498 /* We've possibly created jump to next insn, cleanup_cfg will solve that
3502 num_updated_if_blocks++;
3507 /* Test for case 2 above. */
3510 find_if_case_2 (basic_block test_bb, edge then_edge, edge else_edge)
3512 basic_block then_bb = then_edge->dest;
3513 basic_block else_bb = else_edge->dest;
3517 /* If we are partitioning hot/cold basic blocks, we don't want to
3518 mess up unconditional or indirect jumps that cross between hot
3521 Basic block partitioning may result in some jumps that appear to
3522 be optimizable (or blocks that appear to be mergeable), but which really
3523 must be left untouched (they are required to make it safely across
3524 partition boundaries). See the comments at the top of
3525 bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */
3527 if ((BB_END (then_bb)
3528 && find_reg_note (BB_END (then_bb), REG_CROSSING_JUMP, NULL_RTX))
3529 || (BB_END (test_bb)
3530 && find_reg_note (BB_END (test_bb), REG_CROSSING_JUMP, NULL_RTX))
3531 || (BB_END (else_bb)
3532 && find_reg_note (BB_END (else_bb), REG_CROSSING_JUMP,
3536 /* ELSE has one successor. */
3537 if (!single_succ_p (else_bb))
3540 else_succ = single_succ_edge (else_bb);
3542 /* ELSE outgoing edge is not complex. */
3543 if (else_succ->flags & EDGE_COMPLEX)
3546 /* ELSE has one predecessor. */
3547 if (!single_pred_p (else_bb))
3550 /* THEN is not EXIT. */
3551 if (then_bb->index < NUM_FIXED_BLOCKS)
3554 /* ELSE is predicted or SUCC(ELSE) postdominates THEN. */
3555 note = find_reg_note (BB_END (test_bb), REG_BR_PROB, NULL_RTX);
3556 if (note && INTVAL (XEXP (note, 0)) >= REG_BR_PROB_BASE / 2)
3558 else if (else_succ->dest->index < NUM_FIXED_BLOCKS
3559 || dominated_by_p (CDI_POST_DOMINATORS, then_bb,
3565 num_possible_if_blocks++;
3568 "\nIF-CASE-2 found, start %d, else %d\n",
3569 test_bb->index, else_bb->index);
3571 /* ELSE is small. */
3572 if (! cheap_bb_rtx_cost_p (else_bb, COSTS_N_INSNS (BRANCH_COST)))
3575 /* Registers set are dead, or are predicable. */
3576 if (! dead_or_predicable (test_bb, else_bb, then_bb, else_succ->dest, 0))
3579 /* Conversion went ok, including moving the insns and fixing up the
3580 jump. Adjust the CFG to match. */
3582 bitmap_ior (test_bb->il.rtl->global_live_at_end,
3583 then_bb->il.rtl->global_live_at_start,
3584 else_bb->il.rtl->global_live_at_end);
3586 delete_basic_block (else_bb);
3589 num_updated_if_blocks++;
3591 /* ??? We may now fallthru from one of THEN's successors into a join
3592 block. Rerun cleanup_cfg? Examine things manually? Wait? */
3597 /* A subroutine of dead_or_predicable called through for_each_rtx.
3598 Return 1 if a memory is found. */
3601 find_memory (rtx *px, void *data ATTRIBUTE_UNUSED)
3606 /* Used by the code above to perform the actual rtl transformations.
3607 Return TRUE if successful.
3609 TEST_BB is the block containing the conditional branch. MERGE_BB
3610 is the block containing the code to manipulate. NEW_DEST is the
3611 label TEST_BB should be branching to after the conversion.
3612 REVERSEP is true if the sense of the branch should be reversed. */
3615 dead_or_predicable (basic_block test_bb, basic_block merge_bb,
3616 basic_block other_bb, basic_block new_dest, int reversep)
3618 rtx head, end, jump, earliest = NULL_RTX, old_dest, new_label = NULL_RTX;
3620 jump = BB_END (test_bb);
3622 /* Find the extent of the real code in the merge block. */
3623 head = BB_HEAD (merge_bb);
3624 end = BB_END (merge_bb);
3626 /* If merge_bb ends with a tablejump, predicating/moving insn's
3627 into test_bb and then deleting merge_bb will result in the jumptable
3628 that follows merge_bb being removed along with merge_bb and then we
3629 get an unresolved reference to the jumptable. */
3630 if (tablejump_p (end, NULL, NULL))
3634 head = NEXT_INSN (head);
3639 head = end = NULL_RTX;
3642 head = NEXT_INSN (head);
3649 head = end = NULL_RTX;
3652 end = PREV_INSN (end);
3655 /* Disable handling dead code by conditional execution if the machine needs
3656 to do anything funny with the tests, etc. */
3657 #ifndef IFCVT_MODIFY_TESTS
3658 if (HAVE_conditional_execution)
3660 /* In the conditional execution case, we have things easy. We know
3661 the condition is reversible. We don't have to check life info
3662 because we're going to conditionally execute the code anyway.
3663 All that's left is making sure the insns involved can actually
3668 cond = cond_exec_get_condition (jump);
3672 prob_val = find_reg_note (jump, REG_BR_PROB, NULL_RTX);
3674 prob_val = XEXP (prob_val, 0);
3678 enum rtx_code rev = reversed_comparison_code (cond, jump);
3681 cond = gen_rtx_fmt_ee (rev, GET_MODE (cond), XEXP (cond, 0),
3684 prob_val = GEN_INT (REG_BR_PROB_BASE - INTVAL (prob_val));
3687 if (! cond_exec_process_insns ((ce_if_block_t *)0, head, end, cond,
3696 /* In the non-conditional execution case, we have to verify that there
3697 are no trapping operations, no calls, no references to memory, and
3698 that any registers modified are dead at the branch site. */
3700 rtx insn, cond, prev;
3701 regset merge_set, tmp, test_live, test_set;
3702 struct propagate_block_info *pbi;
3703 unsigned i, fail = 0;
3706 /* Check for no calls or trapping operations. */
3707 for (insn = head; ; insn = NEXT_INSN (insn))
3713 if (may_trap_p (PATTERN (insn)))
3716 /* ??? Even non-trapping memories such as stack frame
3717 references must be avoided. For stores, we collect
3718 no lifetime info; for reads, we'd have to assert
3719 true_dependence false against every store in the
3721 if (for_each_rtx (&PATTERN (insn), find_memory, NULL))
3728 if (! any_condjump_p (jump))
3731 /* Find the extent of the conditional. */
3732 cond = noce_get_condition (jump, &earliest);
3737 MERGE_SET = set of registers set in MERGE_BB
3738 TEST_LIVE = set of registers live at EARLIEST
3739 TEST_SET = set of registers set between EARLIEST and the
3740 end of the block. */
3742 tmp = ALLOC_REG_SET (®_obstack);
3743 merge_set = ALLOC_REG_SET (®_obstack);
3744 test_live = ALLOC_REG_SET (®_obstack);
3745 test_set = ALLOC_REG_SET (®_obstack);
3747 /* ??? bb->local_set is only valid during calculate_global_regs_live,
3748 so we must recompute usage for MERGE_BB. Not so bad, I suppose,
3749 since we've already asserted that MERGE_BB is small. */
3750 /* If we allocated new pseudos (e.g. in the conditional move
3751 expander called from noce_emit_cmove), we must resize the
3753 if (max_regno < max_reg_num ())
3755 max_regno = max_reg_num ();
3756 allocate_reg_info (max_regno, FALSE, FALSE);
3758 propagate_block (merge_bb, tmp, merge_set, merge_set, 0);
3760 /* For small register class machines, don't lengthen lifetimes of
3761 hard registers before reload. */
3762 if (SMALL_REGISTER_CLASSES && ! reload_completed)
3764 EXECUTE_IF_SET_IN_BITMAP (merge_set, 0, i, bi)
3766 if (i < FIRST_PSEUDO_REGISTER
3768 && ! global_regs[i])
3773 /* For TEST, we're interested in a range of insns, not a whole block.
3774 Moreover, we're interested in the insns live from OTHER_BB. */
3776 COPY_REG_SET (test_live, other_bb->il.rtl->global_live_at_start);
3777 pbi = init_propagate_block_info (test_bb, test_live, test_set, test_set,
3780 for (insn = jump; ; insn = prev)
3782 prev = propagate_one_insn (pbi, insn);
3783 if (insn == earliest)
3787 free_propagate_block_info (pbi);
3789 /* We can perform the transformation if
3790 MERGE_SET & (TEST_SET | TEST_LIVE)
3792 TEST_SET & merge_bb->il.rtl->global_live_at_start
3795 if (bitmap_intersect_p (test_set, merge_set)
3796 || bitmap_intersect_p (test_live, merge_set)
3797 || bitmap_intersect_p (test_set,
3798 merge_bb->il.rtl->global_live_at_start))
3802 FREE_REG_SET (merge_set);
3803 FREE_REG_SET (test_live);
3804 FREE_REG_SET (test_set);
3811 /* We don't want to use normal invert_jump or redirect_jump because
3812 we don't want to delete_insn called. Also, we want to do our own
3813 change group management. */
3815 old_dest = JUMP_LABEL (jump);
3816 if (other_bb != new_dest)
3818 new_label = block_label (new_dest);
3820 ? ! invert_jump_1 (jump, new_label)
3821 : ! redirect_jump_1 (jump, new_label))
3825 if (! apply_change_group ())
3828 if (other_bb != new_dest)
3830 redirect_jump_2 (jump, old_dest, new_label, 0, reversep);
3832 redirect_edge_succ (BRANCH_EDGE (test_bb), new_dest);
3835 gcov_type count, probability;
3836 count = BRANCH_EDGE (test_bb)->count;
3837 BRANCH_EDGE (test_bb)->count = FALLTHRU_EDGE (test_bb)->count;
3838 FALLTHRU_EDGE (test_bb)->count = count;
3839 probability = BRANCH_EDGE (test_bb)->probability;
3840 BRANCH_EDGE (test_bb)->probability
3841 = FALLTHRU_EDGE (test_bb)->probability;
3842 FALLTHRU_EDGE (test_bb)->probability = probability;
3843 update_br_prob_note (test_bb);
3847 /* Move the insns out of MERGE_BB to before the branch. */
3852 if (end == BB_END (merge_bb))
3853 BB_END (merge_bb) = PREV_INSN (head);
3855 if (squeeze_notes (&head, &end))
3858 /* PR 21767: When moving insns above a conditional branch, REG_EQUAL
3859 notes might become invalid. */
3865 if (! INSN_P (insn))
3867 note = find_reg_note (insn, REG_EQUAL, NULL_RTX);
3870 set = single_set (insn);
3871 if (!set || !function_invariant_p (SET_SRC (set)))
3872 remove_note (insn, note);
3873 } while (insn != end && (insn = NEXT_INSN (insn)));
3875 reorder_insns (head, end, PREV_INSN (earliest));
3878 /* Remove the jump and edge if we can. */
3879 if (other_bb == new_dest)
3882 remove_edge (BRANCH_EDGE (test_bb));
3883 /* ??? Can't merge blocks here, as then_bb is still in use.
3884 At minimum, the merge will get done just before bb-reorder. */
3894 /* Main entry point for all if-conversion. */
3897 if_convert (int x_life_data_ok)
3902 num_possible_if_blocks = 0;
3903 num_updated_if_blocks = 0;
3904 num_true_changes = 0;
3905 life_data_ok = (x_life_data_ok != 0);
3907 if ((! targetm.cannot_modify_jumps_p ())
3908 && (!flag_reorder_blocks_and_partition || !no_new_pseudos
3909 || !targetm.have_named_sections))
3911 loop_optimizer_init (0);
3914 mark_loop_exit_edges ();
3915 loop_optimizer_finalize ();
3917 free_dominance_info (CDI_DOMINATORS);
3920 /* Compute postdominators if we think we'll use them. */
3921 if (HAVE_conditional_execution || life_data_ok)
3922 calculate_dominance_info (CDI_POST_DOMINATORS);
3927 /* Go through each of the basic blocks looking for things to convert. If we
3928 have conditional execution, we make multiple passes to allow us to handle
3929 IF-THEN{-ELSE} blocks within other IF-THEN{-ELSE} blocks. */
3933 cond_exec_changed_p = FALSE;
3936 #ifdef IFCVT_MULTIPLE_DUMPS
3937 if (dump_file && pass > 1)
3938 fprintf (dump_file, "\n\n========== Pass %d ==========\n", pass);
3944 while ((new_bb = find_if_header (bb, pass)))
3948 #ifdef IFCVT_MULTIPLE_DUMPS
3949 if (dump_file && cond_exec_changed_p)
3950 print_rtl_with_bb (dump_file, get_insns ());
3953 while (cond_exec_changed_p);
3955 #ifdef IFCVT_MULTIPLE_DUMPS
3957 fprintf (dump_file, "\n\n========== no more changes\n");
3960 free_dominance_info (CDI_POST_DOMINATORS);
3965 clear_aux_for_blocks ();
3967 /* Rebuild life info for basic blocks that require it. */
3968 if (num_true_changes && life_data_ok)
3970 /* If we allocated new pseudos, we must resize the array for sched1. */
3971 if (max_regno < max_reg_num ())
3973 max_regno = max_reg_num ();
3974 allocate_reg_info (max_regno, FALSE, FALSE);
3976 update_life_info_in_dirty_blocks (UPDATE_LIFE_GLOBAL_RM_NOTES,
3977 PROP_DEATH_NOTES | PROP_SCAN_DEAD_CODE
3978 | PROP_KILL_DEAD_CODE);
3981 /* Write the final stats. */
3982 if (dump_file && num_possible_if_blocks > 0)
3985 "\n%d possible IF blocks searched.\n",
3986 num_possible_if_blocks);
3988 "%d IF blocks converted.\n",
3989 num_updated_if_blocks);
3991 "%d true changes made.\n\n\n",
3995 #ifdef ENABLE_CHECKING
3996 verify_flow_info ();
4001 gate_handle_if_conversion (void)
4003 return (optimize > 0);
4006 /* If-conversion and CFG cleanup. */
4008 rest_of_handle_if_conversion (void)
4010 if (flag_if_conversion)
4013 dump_flow_info (dump_file, dump_flags);
4014 cleanup_cfg (CLEANUP_EXPENSIVE);
4015 reg_scan (get_insns (), max_reg_num ());
4019 timevar_push (TV_JUMP);
4020 cleanup_cfg (CLEANUP_EXPENSIVE);
4021 reg_scan (get_insns (), max_reg_num ());
4022 timevar_pop (TV_JUMP);
4026 struct tree_opt_pass pass_rtl_ifcvt =
4029 gate_handle_if_conversion, /* gate */
4030 rest_of_handle_if_conversion, /* execute */
4033 0, /* static_pass_number */
4034 TV_IFCVT, /* tv_id */
4035 0, /* properties_required */
4036 0, /* properties_provided */
4037 0, /* properties_destroyed */
4038 0, /* todo_flags_start */
4039 TODO_dump_func, /* todo_flags_finish */
4044 gate_handle_if_after_combine (void)
4046 return (optimize > 0 && flag_if_conversion);
4050 /* Rerun if-conversion, as combine may have simplified things enough
4051 to now meet sequence length restrictions. */
4053 rest_of_handle_if_after_combine (void)
4061 struct tree_opt_pass pass_if_after_combine =
4064 gate_handle_if_after_combine, /* gate */
4065 rest_of_handle_if_after_combine, /* execute */
4068 0, /* static_pass_number */
4069 TV_IFCVT, /* tv_id */
4070 0, /* properties_required */
4071 0, /* properties_provided */
4072 0, /* properties_destroyed */
4073 0, /* todo_flags_start */
4075 TODO_ggc_collect, /* todo_flags_finish */
4081 gate_handle_if_after_reload (void)
4083 return (optimize > 0);
4087 rest_of_handle_if_after_reload (void)
4089 /* Last attempt to optimize CFG, as scheduling, peepholing and insn
4090 splitting possibly introduced more crossjumping opportunities. */
4091 cleanup_cfg (CLEANUP_EXPENSIVE
4092 | CLEANUP_UPDATE_LIFE
4093 | (flag_crossjumping ? CLEANUP_CROSSJUMP : 0));
4094 if (flag_if_conversion2)
4100 struct tree_opt_pass pass_if_after_reload =
4103 gate_handle_if_after_reload, /* gate */
4104 rest_of_handle_if_after_reload, /* execute */
4107 0, /* static_pass_number */
4108 TV_IFCVT2, /* tv_id */
4109 0, /* properties_required */
4110 0, /* properties_provided */
4111 0, /* properties_destroyed */
4112 0, /* todo_flags_start */
4114 TODO_ggc_collect, /* todo_flags_finish */