1 /* If-conversion support.
2 Copyright (C) 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008
3 Free Software Foundation, Inc.
5 This file is part of GCC.
7 GCC is free software; you can redistribute it and/or modify it
8 under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 3, or (at your option)
12 GCC is distributed in the hope that it will be useful, but WITHOUT
13 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
14 or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public
15 License for more details.
17 You should have received a copy of the GNU General Public License
18 along with GCC; see the file COPYING3. If not see
19 <http://www.gnu.org/licenses/>. */
23 #include "coretypes.h"
30 #include "insn-config.h"
33 #include "hard-reg-set.h"
34 #include "basic-block.h"
44 #include "tree-pass.h"
50 #ifndef HAVE_conditional_move
51 #define HAVE_conditional_move 0
63 #ifndef MAX_CONDITIONAL_EXECUTE
64 #define MAX_CONDITIONAL_EXECUTE \
65 (BRANCH_COST (optimize_function_for_speed_p (cfun), false) \
69 #define IFCVT_MULTIPLE_DUMPS 1
71 #define NULL_BLOCK ((basic_block) NULL)
73 /* # of IF-THEN or IF-THEN-ELSE blocks we looked at */
74 static int num_possible_if_blocks;
76 /* # of IF-THEN or IF-THEN-ELSE blocks were converted to conditional
78 static int num_updated_if_blocks;
80 /* # of changes made. */
81 static int num_true_changes;
83 /* Whether conditional execution changes were made. */
84 static int cond_exec_changed_p;
86 /* Forward references. */
87 static int count_bb_insns (const_basic_block);
88 static bool cheap_bb_rtx_cost_p (const_basic_block, int);
89 static rtx first_active_insn (basic_block);
90 static rtx last_active_insn (basic_block, int);
91 static basic_block block_fallthru (basic_block);
92 static int cond_exec_process_insns (ce_if_block_t *, rtx, rtx, rtx, rtx, int);
93 static rtx cond_exec_get_condition (rtx);
94 static rtx noce_get_condition (rtx, rtx *, bool);
95 static int noce_operand_ok (const_rtx);
96 static void merge_if_block (ce_if_block_t *);
97 static int find_cond_trap (basic_block, edge, edge);
98 static basic_block find_if_header (basic_block, int);
99 static int block_jumps_and_fallthru_p (basic_block, basic_block);
100 static int noce_find_if_block (basic_block, edge, edge, int);
101 static int cond_exec_find_if_block (ce_if_block_t *);
102 static int find_if_case_1 (basic_block, edge, edge);
103 static int find_if_case_2 (basic_block, edge, edge);
104 static int find_memory (rtx *, void *);
105 static int dead_or_predicable (basic_block, basic_block, basic_block,
107 static void noce_emit_move_insn (rtx, rtx);
108 static rtx block_has_only_trap (basic_block);
110 /* Count the number of non-jump active insns in BB. */
113 count_bb_insns (const_basic_block bb)
116 rtx insn = BB_HEAD (bb);
120 if (CALL_P (insn) || NONJUMP_INSN_P (insn))
123 if (insn == BB_END (bb))
125 insn = NEXT_INSN (insn);
131 /* Determine whether the total insn_rtx_cost on non-jump insns in
132 basic block BB is less than MAX_COST. This function returns
133 false if the cost of any instruction could not be estimated. */
136 cheap_bb_rtx_cost_p (const_basic_block bb, int max_cost)
139 rtx insn = BB_HEAD (bb);
140 bool speed = optimize_bb_for_speed_p (bb);
144 if (NONJUMP_INSN_P (insn))
146 int cost = insn_rtx_cost (PATTERN (insn), speed);
150 /* If this instruction is the load or set of a "stack" register,
151 such as a floating point register on x87, then the cost of
152 speculatively executing this insn may need to include
153 the additional cost of popping its result off of the
154 register stack. Unfortunately, correctly recognizing and
155 accounting for this additional overhead is tricky, so for
156 now we simply prohibit such speculative execution. */
159 rtx set = single_set (insn);
160 if (set && STACK_REG_P (SET_DEST (set)))
166 if (count >= max_cost)
169 else if (CALL_P (insn))
172 if (insn == BB_END (bb))
174 insn = NEXT_INSN (insn);
180 /* Return the first non-jump active insn in the basic block. */
183 first_active_insn (basic_block bb)
185 rtx insn = BB_HEAD (bb);
189 if (insn == BB_END (bb))
191 insn = NEXT_INSN (insn);
194 while (NOTE_P (insn) || DEBUG_INSN_P (insn))
196 if (insn == BB_END (bb))
198 insn = NEXT_INSN (insn);
207 /* Return the last non-jump active (non-jump) insn in the basic block. */
210 last_active_insn (basic_block bb, int skip_use_p)
212 rtx insn = BB_END (bb);
213 rtx head = BB_HEAD (bb);
217 || DEBUG_INSN_P (insn)
219 && NONJUMP_INSN_P (insn)
220 && GET_CODE (PATTERN (insn)) == USE))
224 insn = PREV_INSN (insn);
233 /* Return the basic block reached by falling though the basic block BB. */
236 block_fallthru (basic_block bb)
241 FOR_EACH_EDGE (e, ei, bb->succs)
242 if (e->flags & EDGE_FALLTHRU)
245 return (e) ? e->dest : NULL_BLOCK;
248 /* Go through a bunch of insns, converting them to conditional
249 execution format if possible. Return TRUE if all of the non-note
250 insns were processed. */
253 cond_exec_process_insns (ce_if_block_t *ce_info ATTRIBUTE_UNUSED,
254 /* if block information */rtx start,
255 /* first insn to look at */rtx end,
256 /* last insn to look at */rtx test,
257 /* conditional execution test */rtx prob_val,
258 /* probability of branch taken. */int mod_ok)
260 int must_be_last = FALSE;
268 for (insn = start; ; insn = NEXT_INSN (insn))
270 if (NOTE_P (insn) || DEBUG_INSN_P (insn))
273 gcc_assert(NONJUMP_INSN_P (insn) || CALL_P (insn));
275 /* Remove USE insns that get in the way. */
276 if (reload_completed && GET_CODE (PATTERN (insn)) == USE)
278 /* ??? Ug. Actually unlinking the thing is problematic,
279 given what we'd have to coordinate with our callers. */
280 SET_INSN_DELETED (insn);
284 /* Last insn wasn't last? */
288 if (modified_in_p (test, insn))
295 /* Now build the conditional form of the instruction. */
296 pattern = PATTERN (insn);
297 xtest = copy_rtx (test);
299 /* If this is already a COND_EXEC, rewrite the test to be an AND of the
301 if (GET_CODE (pattern) == COND_EXEC)
303 if (GET_MODE (xtest) != GET_MODE (COND_EXEC_TEST (pattern)))
306 xtest = gen_rtx_AND (GET_MODE (xtest), xtest,
307 COND_EXEC_TEST (pattern));
308 pattern = COND_EXEC_CODE (pattern);
311 pattern = gen_rtx_COND_EXEC (VOIDmode, xtest, pattern);
313 /* If the machine needs to modify the insn being conditionally executed,
314 say for example to force a constant integer operand into a temp
315 register, do so here. */
316 #ifdef IFCVT_MODIFY_INSN
317 IFCVT_MODIFY_INSN (ce_info, pattern, insn);
322 validate_change (insn, &PATTERN (insn), pattern, 1);
324 if (CALL_P (insn) && prob_val)
325 validate_change (insn, ®_NOTES (insn),
326 alloc_EXPR_LIST (REG_BR_PROB, prob_val,
327 REG_NOTES (insn)), 1);
337 /* Return the condition for a jump. Do not do any special processing. */
340 cond_exec_get_condition (rtx jump)
344 if (any_condjump_p (jump))
345 test_if = SET_SRC (pc_set (jump));
348 cond = XEXP (test_if, 0);
350 /* If this branches to JUMP_LABEL when the condition is false,
351 reverse the condition. */
352 if (GET_CODE (XEXP (test_if, 2)) == LABEL_REF
353 && XEXP (XEXP (test_if, 2), 0) == JUMP_LABEL (jump))
355 enum rtx_code rev = reversed_comparison_code (cond, jump);
359 cond = gen_rtx_fmt_ee (rev, GET_MODE (cond), XEXP (cond, 0),
366 /* Given a simple IF-THEN or IF-THEN-ELSE block, attempt to convert it
367 to conditional execution. Return TRUE if we were successful at
368 converting the block. */
371 cond_exec_process_if_block (ce_if_block_t * ce_info,
372 /* if block information */int do_multiple_p)
374 basic_block test_bb = ce_info->test_bb; /* last test block */
375 basic_block then_bb = ce_info->then_bb; /* THEN */
376 basic_block else_bb = ce_info->else_bb; /* ELSE or NULL */
377 rtx test_expr; /* expression in IF_THEN_ELSE that is tested */
378 rtx then_start; /* first insn in THEN block */
379 rtx then_end; /* last insn + 1 in THEN block */
380 rtx else_start = NULL_RTX; /* first insn in ELSE block or NULL */
381 rtx else_end = NULL_RTX; /* last insn + 1 in ELSE block */
382 int max; /* max # of insns to convert. */
383 int then_mod_ok; /* whether conditional mods are ok in THEN */
384 rtx true_expr; /* test for else block insns */
385 rtx false_expr; /* test for then block insns */
386 rtx true_prob_val; /* probability of else block */
387 rtx false_prob_val; /* probability of then block */
389 enum rtx_code false_code;
391 /* If test is comprised of && or || elements, and we've failed at handling
392 all of them together, just use the last test if it is the special case of
393 && elements without an ELSE block. */
394 if (!do_multiple_p && ce_info->num_multiple_test_blocks)
396 if (else_bb || ! ce_info->and_and_p)
399 ce_info->test_bb = test_bb = ce_info->last_test_bb;
400 ce_info->num_multiple_test_blocks = 0;
401 ce_info->num_and_and_blocks = 0;
402 ce_info->num_or_or_blocks = 0;
405 /* Find the conditional jump to the ELSE or JOIN part, and isolate
407 test_expr = cond_exec_get_condition (BB_END (test_bb));
411 /* If the conditional jump is more than just a conditional jump,
412 then we can not do conditional execution conversion on this block. */
413 if (! onlyjump_p (BB_END (test_bb)))
416 /* Collect the bounds of where we're to search, skipping any labels, jumps
417 and notes at the beginning and end of the block. Then count the total
418 number of insns and see if it is small enough to convert. */
419 then_start = first_active_insn (then_bb);
420 then_end = last_active_insn (then_bb, TRUE);
421 n_insns = ce_info->num_then_insns = count_bb_insns (then_bb);
422 max = MAX_CONDITIONAL_EXECUTE;
427 else_start = first_active_insn (else_bb);
428 else_end = last_active_insn (else_bb, TRUE);
429 n_insns += ce_info->num_else_insns = count_bb_insns (else_bb);
435 /* Map test_expr/test_jump into the appropriate MD tests to use on
436 the conditionally executed code. */
438 true_expr = test_expr;
440 false_code = reversed_comparison_code (true_expr, BB_END (test_bb));
441 if (false_code != UNKNOWN)
442 false_expr = gen_rtx_fmt_ee (false_code, GET_MODE (true_expr),
443 XEXP (true_expr, 0), XEXP (true_expr, 1));
445 false_expr = NULL_RTX;
447 #ifdef IFCVT_MODIFY_TESTS
448 /* If the machine description needs to modify the tests, such as setting a
449 conditional execution register from a comparison, it can do so here. */
450 IFCVT_MODIFY_TESTS (ce_info, true_expr, false_expr);
452 /* See if the conversion failed. */
453 if (!true_expr || !false_expr)
457 true_prob_val = find_reg_note (BB_END (test_bb), REG_BR_PROB, NULL_RTX);
460 true_prob_val = XEXP (true_prob_val, 0);
461 false_prob_val = GEN_INT (REG_BR_PROB_BASE - INTVAL (true_prob_val));
464 false_prob_val = NULL_RTX;
466 /* If we have && or || tests, do them here. These tests are in the adjacent
467 blocks after the first block containing the test. */
468 if (ce_info->num_multiple_test_blocks > 0)
470 basic_block bb = test_bb;
471 basic_block last_test_bb = ce_info->last_test_bb;
480 enum rtx_code f_code;
482 bb = block_fallthru (bb);
483 start = first_active_insn (bb);
484 end = last_active_insn (bb, TRUE);
486 && ! cond_exec_process_insns (ce_info, start, end, false_expr,
487 false_prob_val, FALSE))
490 /* If the conditional jump is more than just a conditional jump, then
491 we can not do conditional execution conversion on this block. */
492 if (! onlyjump_p (BB_END (bb)))
495 /* Find the conditional jump and isolate the test. */
496 t = cond_exec_get_condition (BB_END (bb));
500 f_code = reversed_comparison_code (t, BB_END (bb));
501 if (f_code == UNKNOWN)
504 f = gen_rtx_fmt_ee (f_code, GET_MODE (t), XEXP (t, 0), XEXP (t, 1));
505 if (ce_info->and_and_p)
507 t = gen_rtx_AND (GET_MODE (t), true_expr, t);
508 f = gen_rtx_IOR (GET_MODE (t), false_expr, f);
512 t = gen_rtx_IOR (GET_MODE (t), true_expr, t);
513 f = gen_rtx_AND (GET_MODE (t), false_expr, f);
516 /* If the machine description needs to modify the tests, such as
517 setting a conditional execution register from a comparison, it can
519 #ifdef IFCVT_MODIFY_MULTIPLE_TESTS
520 IFCVT_MODIFY_MULTIPLE_TESTS (ce_info, bb, t, f);
522 /* See if the conversion failed. */
530 while (bb != last_test_bb);
533 /* For IF-THEN-ELSE blocks, we don't allow modifications of the test
534 on then THEN block. */
535 then_mod_ok = (else_bb == NULL_BLOCK);
537 /* Go through the THEN and ELSE blocks converting the insns if possible
538 to conditional execution. */
542 || ! cond_exec_process_insns (ce_info, then_start, then_end,
543 false_expr, false_prob_val,
547 if (else_bb && else_end
548 && ! cond_exec_process_insns (ce_info, else_start, else_end,
549 true_expr, true_prob_val, TRUE))
552 /* If we cannot apply the changes, fail. Do not go through the normal fail
553 processing, since apply_change_group will call cancel_changes. */
554 if (! apply_change_group ())
556 #ifdef IFCVT_MODIFY_CANCEL
557 /* Cancel any machine dependent changes. */
558 IFCVT_MODIFY_CANCEL (ce_info);
563 #ifdef IFCVT_MODIFY_FINAL
564 /* Do any machine dependent final modifications. */
565 IFCVT_MODIFY_FINAL (ce_info);
568 /* Conversion succeeded. */
570 fprintf (dump_file, "%d insn%s converted to conditional execution.\n",
571 n_insns, (n_insns == 1) ? " was" : "s were");
573 /* Merge the blocks! */
574 merge_if_block (ce_info);
575 cond_exec_changed_p = TRUE;
579 #ifdef IFCVT_MODIFY_CANCEL
580 /* Cancel any machine dependent changes. */
581 IFCVT_MODIFY_CANCEL (ce_info);
588 /* Used by noce_process_if_block to communicate with its subroutines.
590 The subroutines know that A and B may be evaluated freely. They
591 know that X is a register. They should insert new instructions
592 before cond_earliest. */
596 /* The basic blocks that make up the IF-THEN-{ELSE-,}JOIN block. */
597 basic_block test_bb, then_bb, else_bb, join_bb;
599 /* The jump that ends TEST_BB. */
602 /* The jump condition. */
605 /* New insns should be inserted before this one. */
608 /* Insns in the THEN and ELSE block. There is always just this
609 one insns in those blocks. The insns are single_set insns.
610 If there was no ELSE block, INSN_B is the last insn before
611 COND_EARLIEST, or NULL_RTX. In the former case, the insn
612 operands are still valid, as if INSN_B was moved down below
616 /* The SET_SRC of INSN_A and INSN_B. */
619 /* The SET_DEST of INSN_A. */
622 /* True if this if block is not canonical. In the canonical form of
623 if blocks, the THEN_BB is the block reached via the fallthru edge
624 from TEST_BB. For the noce transformations, we allow the symmetric
626 bool then_else_reversed;
628 /* Estimated cost of the particular branch instruction. */
632 static rtx noce_emit_store_flag (struct noce_if_info *, rtx, int, int);
633 static int noce_try_move (struct noce_if_info *);
634 static int noce_try_store_flag (struct noce_if_info *);
635 static int noce_try_addcc (struct noce_if_info *);
636 static int noce_try_store_flag_constants (struct noce_if_info *);
637 static int noce_try_store_flag_mask (struct noce_if_info *);
638 static rtx noce_emit_cmove (struct noce_if_info *, rtx, enum rtx_code, rtx,
640 static int noce_try_cmove (struct noce_if_info *);
641 static int noce_try_cmove_arith (struct noce_if_info *);
642 static rtx noce_get_alt_condition (struct noce_if_info *, rtx, rtx *);
643 static int noce_try_minmax (struct noce_if_info *);
644 static int noce_try_abs (struct noce_if_info *);
645 static int noce_try_sign_mask (struct noce_if_info *);
647 /* Helper function for noce_try_store_flag*. */
650 noce_emit_store_flag (struct noce_if_info *if_info, rtx x, int reversep,
653 rtx cond = if_info->cond;
657 cond_complex = (! general_operand (XEXP (cond, 0), VOIDmode)
658 || ! general_operand (XEXP (cond, 1), VOIDmode));
660 /* If earliest == jump, or when the condition is complex, try to
661 build the store_flag insn directly. */
665 rtx set = pc_set (if_info->jump);
666 cond = XEXP (SET_SRC (set), 0);
667 if (GET_CODE (XEXP (SET_SRC (set), 2)) == LABEL_REF
668 && XEXP (XEXP (SET_SRC (set), 2), 0) == JUMP_LABEL (if_info->jump))
669 reversep = !reversep;
670 if (if_info->then_else_reversed)
671 reversep = !reversep;
675 code = reversed_comparison_code (cond, if_info->jump);
677 code = GET_CODE (cond);
679 if ((if_info->cond_earliest == if_info->jump || cond_complex)
680 && (normalize == 0 || STORE_FLAG_VALUE == normalize))
684 tmp = gen_rtx_fmt_ee (code, GET_MODE (x), XEXP (cond, 0),
686 tmp = gen_rtx_SET (VOIDmode, x, tmp);
689 tmp = emit_insn (tmp);
691 if (recog_memoized (tmp) >= 0)
697 if_info->cond_earliest = if_info->jump;
705 /* Don't even try if the comparison operands or the mode of X are weird. */
706 if (cond_complex || !SCALAR_INT_MODE_P (GET_MODE (x)))
709 return emit_store_flag (x, code, XEXP (cond, 0),
710 XEXP (cond, 1), VOIDmode,
711 (code == LTU || code == LEU
712 || code == GEU || code == GTU), normalize);
715 /* Emit instruction to move an rtx, possibly into STRICT_LOW_PART.
716 X is the destination/target and Y is the value to copy. */
719 noce_emit_move_insn (rtx x, rtx y)
721 enum machine_mode outmode;
725 if (GET_CODE (x) != STRICT_LOW_PART)
727 rtx seq, insn, target;
731 /* Check that the SET_SRC is reasonable before calling emit_move_insn,
732 otherwise construct a suitable SET pattern ourselves. */
733 insn = (OBJECT_P (y) || CONSTANT_P (y) || GET_CODE (y) == SUBREG)
734 ? emit_move_insn (x, y)
735 : emit_insn (gen_rtx_SET (VOIDmode, x, y));
739 if (recog_memoized (insn) <= 0)
741 if (GET_CODE (x) == ZERO_EXTRACT)
743 rtx op = XEXP (x, 0);
744 unsigned HOST_WIDE_INT size = INTVAL (XEXP (x, 1));
745 unsigned HOST_WIDE_INT start = INTVAL (XEXP (x, 2));
747 /* store_bit_field expects START to be relative to
748 BYTES_BIG_ENDIAN and adjusts this value for machines with
749 BITS_BIG_ENDIAN != BYTES_BIG_ENDIAN. In order to be able to
750 invoke store_bit_field again it is necessary to have the START
751 value from the first call. */
752 if (BITS_BIG_ENDIAN != BYTES_BIG_ENDIAN)
755 start = BITS_PER_UNIT - start - size;
758 gcc_assert (REG_P (op));
759 start = BITS_PER_WORD - start - size;
763 gcc_assert (start < (MEM_P (op) ? BITS_PER_UNIT : BITS_PER_WORD));
764 store_bit_field (op, size, start, GET_MODE (x), y);
768 switch (GET_RTX_CLASS (GET_CODE (y)))
771 ot = code_to_optab[GET_CODE (y)];
775 target = expand_unop (GET_MODE (y), ot, XEXP (y, 0), x, 0);
776 if (target != NULL_RTX)
779 emit_move_insn (x, target);
788 ot = code_to_optab[GET_CODE (y)];
792 target = expand_binop (GET_MODE (y), ot,
793 XEXP (y, 0), XEXP (y, 1),
795 if (target != NULL_RTX)
798 emit_move_insn (x, target);
815 inner = XEXP (outer, 0);
816 outmode = GET_MODE (outer);
817 bitpos = SUBREG_BYTE (outer) * BITS_PER_UNIT;
818 store_bit_field (inner, GET_MODE_BITSIZE (outmode), bitpos, outmode, y);
821 /* Return sequence of instructions generated by if conversion. This
822 function calls end_sequence() to end the current stream, ensures
823 that are instructions are unshared, recognizable non-jump insns.
824 On failure, this function returns a NULL_RTX. */
827 end_ifcvt_sequence (struct noce_if_info *if_info)
830 rtx seq = get_insns ();
832 set_used_flags (if_info->x);
833 set_used_flags (if_info->cond);
834 unshare_all_rtl_in_chain (seq);
837 /* Make sure that all of the instructions emitted are recognizable,
838 and that we haven't introduced a new jump instruction.
839 As an exercise for the reader, build a general mechanism that
840 allows proper placement of required clobbers. */
841 for (insn = seq; insn; insn = NEXT_INSN (insn))
843 || recog_memoized (insn) == -1)
849 /* Convert "if (a != b) x = a; else x = b" into "x = a" and
850 "if (a == b) x = a; else x = b" into "x = b". */
853 noce_try_move (struct noce_if_info *if_info)
855 rtx cond = if_info->cond;
856 enum rtx_code code = GET_CODE (cond);
859 if (code != NE && code != EQ)
862 /* This optimization isn't valid if either A or B could be a NaN
864 if (HONOR_NANS (GET_MODE (if_info->x))
865 || HONOR_SIGNED_ZEROS (GET_MODE (if_info->x)))
868 /* Check whether the operands of the comparison are A and in
870 if ((rtx_equal_p (if_info->a, XEXP (cond, 0))
871 && rtx_equal_p (if_info->b, XEXP (cond, 1)))
872 || (rtx_equal_p (if_info->a, XEXP (cond, 1))
873 && rtx_equal_p (if_info->b, XEXP (cond, 0))))
875 y = (code == EQ) ? if_info->a : if_info->b;
877 /* Avoid generating the move if the source is the destination. */
878 if (! rtx_equal_p (if_info->x, y))
881 noce_emit_move_insn (if_info->x, y);
882 seq = end_ifcvt_sequence (if_info);
886 emit_insn_before_setloc (seq, if_info->jump,
887 INSN_LOCATOR (if_info->insn_a));
894 /* Convert "if (test) x = 1; else x = 0".
896 Only try 0 and STORE_FLAG_VALUE here. Other combinations will be
897 tried in noce_try_store_flag_constants after noce_try_cmove has had
898 a go at the conversion. */
901 noce_try_store_flag (struct noce_if_info *if_info)
906 if (CONST_INT_P (if_info->b)
907 && INTVAL (if_info->b) == STORE_FLAG_VALUE
908 && if_info->a == const0_rtx)
910 else if (if_info->b == const0_rtx
911 && CONST_INT_P (if_info->a)
912 && INTVAL (if_info->a) == STORE_FLAG_VALUE
913 && (reversed_comparison_code (if_info->cond, if_info->jump)
921 target = noce_emit_store_flag (if_info, if_info->x, reversep, 0);
924 if (target != if_info->x)
925 noce_emit_move_insn (if_info->x, target);
927 seq = end_ifcvt_sequence (if_info);
931 emit_insn_before_setloc (seq, if_info->jump,
932 INSN_LOCATOR (if_info->insn_a));
942 /* Convert "if (test) x = a; else x = b", for A and B constant. */
945 noce_try_store_flag_constants (struct noce_if_info *if_info)
949 HOST_WIDE_INT itrue, ifalse, diff, tmp;
950 int normalize, can_reverse;
951 enum machine_mode mode;
953 if (CONST_INT_P (if_info->a)
954 && CONST_INT_P (if_info->b))
956 mode = GET_MODE (if_info->x);
957 ifalse = INTVAL (if_info->a);
958 itrue = INTVAL (if_info->b);
960 /* Make sure we can represent the difference between the two values. */
961 if ((itrue - ifalse > 0)
962 != ((ifalse < 0) != (itrue < 0) ? ifalse < 0 : ifalse < itrue))
965 diff = trunc_int_for_mode (itrue - ifalse, mode);
967 can_reverse = (reversed_comparison_code (if_info->cond, if_info->jump)
971 if (diff == STORE_FLAG_VALUE || diff == -STORE_FLAG_VALUE)
973 else if (ifalse == 0 && exact_log2 (itrue) >= 0
974 && (STORE_FLAG_VALUE == 1
975 || if_info->branch_cost >= 2))
977 else if (itrue == 0 && exact_log2 (ifalse) >= 0 && can_reverse
978 && (STORE_FLAG_VALUE == 1 || if_info->branch_cost >= 2))
979 normalize = 1, reversep = 1;
981 && (STORE_FLAG_VALUE == -1
982 || if_info->branch_cost >= 2))
984 else if (ifalse == -1 && can_reverse
985 && (STORE_FLAG_VALUE == -1 || if_info->branch_cost >= 2))
986 normalize = -1, reversep = 1;
987 else if ((if_info->branch_cost >= 2 && STORE_FLAG_VALUE == -1)
988 || if_info->branch_cost >= 3)
995 tmp = itrue; itrue = ifalse; ifalse = tmp;
996 diff = trunc_int_for_mode (-diff, mode);
1000 target = noce_emit_store_flag (if_info, if_info->x, reversep, normalize);
1007 /* if (test) x = 3; else x = 4;
1008 => x = 3 + (test == 0); */
1009 if (diff == STORE_FLAG_VALUE || diff == -STORE_FLAG_VALUE)
1011 target = expand_simple_binop (mode,
1012 (diff == STORE_FLAG_VALUE
1014 GEN_INT (ifalse), target, if_info->x, 0,
1018 /* if (test) x = 8; else x = 0;
1019 => x = (test != 0) << 3; */
1020 else if (ifalse == 0 && (tmp = exact_log2 (itrue)) >= 0)
1022 target = expand_simple_binop (mode, ASHIFT,
1023 target, GEN_INT (tmp), if_info->x, 0,
1027 /* if (test) x = -1; else x = b;
1028 => x = -(test != 0) | b; */
1029 else if (itrue == -1)
1031 target = expand_simple_binop (mode, IOR,
1032 target, GEN_INT (ifalse), if_info->x, 0,
1036 /* if (test) x = a; else x = b;
1037 => x = (-(test != 0) & (b - a)) + a; */
1040 target = expand_simple_binop (mode, AND,
1041 target, GEN_INT (diff), if_info->x, 0,
1044 target = expand_simple_binop (mode, PLUS,
1045 target, GEN_INT (ifalse),
1046 if_info->x, 0, OPTAB_WIDEN);
1055 if (target != if_info->x)
1056 noce_emit_move_insn (if_info->x, target);
1058 seq = end_ifcvt_sequence (if_info);
1062 emit_insn_before_setloc (seq, if_info->jump,
1063 INSN_LOCATOR (if_info->insn_a));
1070 /* Convert "if (test) foo++" into "foo += (test != 0)", and
1071 similarly for "foo--". */
1074 noce_try_addcc (struct noce_if_info *if_info)
1077 int subtract, normalize;
1079 if (GET_CODE (if_info->a) == PLUS
1080 && rtx_equal_p (XEXP (if_info->a, 0), if_info->b)
1081 && (reversed_comparison_code (if_info->cond, if_info->jump)
1084 rtx cond = if_info->cond;
1085 enum rtx_code code = reversed_comparison_code (cond, if_info->jump);
1087 /* First try to use addcc pattern. */
1088 if (general_operand (XEXP (cond, 0), VOIDmode)
1089 && general_operand (XEXP (cond, 1), VOIDmode))
1092 target = emit_conditional_add (if_info->x, code,
1097 XEXP (if_info->a, 1),
1098 GET_MODE (if_info->x),
1099 (code == LTU || code == GEU
1100 || code == LEU || code == GTU));
1103 if (target != if_info->x)
1104 noce_emit_move_insn (if_info->x, target);
1106 seq = end_ifcvt_sequence (if_info);
1110 emit_insn_before_setloc (seq, if_info->jump,
1111 INSN_LOCATOR (if_info->insn_a));
1117 /* If that fails, construct conditional increment or decrement using
1119 if (if_info->branch_cost >= 2
1120 && (XEXP (if_info->a, 1) == const1_rtx
1121 || XEXP (if_info->a, 1) == constm1_rtx))
1124 if (STORE_FLAG_VALUE == INTVAL (XEXP (if_info->a, 1)))
1125 subtract = 0, normalize = 0;
1126 else if (-STORE_FLAG_VALUE == INTVAL (XEXP (if_info->a, 1)))
1127 subtract = 1, normalize = 0;
1129 subtract = 0, normalize = INTVAL (XEXP (if_info->a, 1));
1132 target = noce_emit_store_flag (if_info,
1133 gen_reg_rtx (GET_MODE (if_info->x)),
1137 target = expand_simple_binop (GET_MODE (if_info->x),
1138 subtract ? MINUS : PLUS,
1139 if_info->b, target, if_info->x,
1143 if (target != if_info->x)
1144 noce_emit_move_insn (if_info->x, target);
1146 seq = end_ifcvt_sequence (if_info);
1150 emit_insn_before_setloc (seq, if_info->jump,
1151 INSN_LOCATOR (if_info->insn_a));
1161 /* Convert "if (test) x = 0;" to "x &= -(test == 0);" */
1164 noce_try_store_flag_mask (struct noce_if_info *if_info)
1170 if ((if_info->branch_cost >= 2
1171 || STORE_FLAG_VALUE == -1)
1172 && ((if_info->a == const0_rtx
1173 && rtx_equal_p (if_info->b, if_info->x))
1174 || ((reversep = (reversed_comparison_code (if_info->cond,
1177 && if_info->b == const0_rtx
1178 && rtx_equal_p (if_info->a, if_info->x))))
1181 target = noce_emit_store_flag (if_info,
1182 gen_reg_rtx (GET_MODE (if_info->x)),
1185 target = expand_simple_binop (GET_MODE (if_info->x), AND,
1187 target, if_info->x, 0,
1192 if (target != if_info->x)
1193 noce_emit_move_insn (if_info->x, target);
1195 seq = end_ifcvt_sequence (if_info);
1199 emit_insn_before_setloc (seq, if_info->jump,
1200 INSN_LOCATOR (if_info->insn_a));
1210 /* Helper function for noce_try_cmove and noce_try_cmove_arith. */
1213 noce_emit_cmove (struct noce_if_info *if_info, rtx x, enum rtx_code code,
1214 rtx cmp_a, rtx cmp_b, rtx vfalse, rtx vtrue)
1216 /* If earliest == jump, try to build the cmove insn directly.
1217 This is helpful when combine has created some complex condition
1218 (like for alpha's cmovlbs) that we can't hope to regenerate
1219 through the normal interface. */
1221 if (if_info->cond_earliest == if_info->jump)
1225 tmp = gen_rtx_fmt_ee (code, GET_MODE (if_info->cond), cmp_a, cmp_b);
1226 tmp = gen_rtx_IF_THEN_ELSE (GET_MODE (x), tmp, vtrue, vfalse);
1227 tmp = gen_rtx_SET (VOIDmode, x, tmp);
1230 tmp = emit_insn (tmp);
1232 if (recog_memoized (tmp) >= 0)
1244 /* Don't even try if the comparison operands are weird. */
1245 if (! general_operand (cmp_a, GET_MODE (cmp_a))
1246 || ! general_operand (cmp_b, GET_MODE (cmp_b)))
1249 #if HAVE_conditional_move
1250 return emit_conditional_move (x, code, cmp_a, cmp_b, VOIDmode,
1251 vtrue, vfalse, GET_MODE (x),
1252 (code == LTU || code == GEU
1253 || code == LEU || code == GTU));
1255 /* We'll never get here, as noce_process_if_block doesn't call the
1256 functions involved. Ifdef code, however, should be discouraged
1257 because it leads to typos in the code not selected. However,
1258 emit_conditional_move won't exist either. */
1263 /* Try only simple constants and registers here. More complex cases
1264 are handled in noce_try_cmove_arith after noce_try_store_flag_arith
1265 has had a go at it. */
1268 noce_try_cmove (struct noce_if_info *if_info)
1273 if ((CONSTANT_P (if_info->a) || register_operand (if_info->a, VOIDmode))
1274 && (CONSTANT_P (if_info->b) || register_operand (if_info->b, VOIDmode)))
1278 code = GET_CODE (if_info->cond);
1279 target = noce_emit_cmove (if_info, if_info->x, code,
1280 XEXP (if_info->cond, 0),
1281 XEXP (if_info->cond, 1),
1282 if_info->a, if_info->b);
1286 if (target != if_info->x)
1287 noce_emit_move_insn (if_info->x, target);
1289 seq = end_ifcvt_sequence (if_info);
1293 emit_insn_before_setloc (seq, if_info->jump,
1294 INSN_LOCATOR (if_info->insn_a));
1307 /* Try more complex cases involving conditional_move. */
1310 noce_try_cmove_arith (struct noce_if_info *if_info)
1322 /* A conditional move from two memory sources is equivalent to a
1323 conditional on their addresses followed by a load. Don't do this
1324 early because it'll screw alias analysis. Note that we've
1325 already checked for no side effects. */
1326 /* ??? FIXME: Magic number 5. */
1327 if (cse_not_expected
1328 && MEM_P (a) && MEM_P (b)
1329 && MEM_ADDR_SPACE (a) == MEM_ADDR_SPACE (b)
1330 && if_info->branch_cost >= 5)
1332 enum machine_mode address_mode
1333 = targetm.addr_space.address_mode (MEM_ADDR_SPACE (a));
1337 x = gen_reg_rtx (address_mode);
1341 /* ??? We could handle this if we knew that a load from A or B could
1342 not fault. This is also true if we've already loaded
1343 from the address along the path from ENTRY. */
1344 else if (may_trap_p (a) || may_trap_p (b))
1347 /* if (test) x = a + b; else x = c - d;
1354 code = GET_CODE (if_info->cond);
1355 insn_a = if_info->insn_a;
1356 insn_b = if_info->insn_b;
1358 /* Total insn_rtx_cost should be smaller than branch cost. Exit
1359 if insn_rtx_cost can't be estimated. */
1362 insn_cost = insn_rtx_cost (PATTERN (insn_a),
1363 optimize_bb_for_speed_p (BLOCK_FOR_INSN (insn_a)));
1364 if (insn_cost == 0 || insn_cost > COSTS_N_INSNS (if_info->branch_cost))
1372 insn_cost += insn_rtx_cost (PATTERN (insn_b),
1373 optimize_bb_for_speed_p (BLOCK_FOR_INSN (insn_b)));
1374 if (insn_cost == 0 || insn_cost > COSTS_N_INSNS (if_info->branch_cost))
1378 /* Possibly rearrange operands to make things come out more natural. */
1379 if (reversed_comparison_code (if_info->cond, if_info->jump) != UNKNOWN)
1382 if (rtx_equal_p (b, x))
1384 else if (general_operand (b, GET_MODE (b)))
1389 code = reversed_comparison_code (if_info->cond, if_info->jump);
1390 tmp = a, a = b, b = tmp;
1391 tmp = insn_a, insn_a = insn_b, insn_b = tmp;
1400 /* If either operand is complex, load it into a register first.
1401 The best way to do this is to copy the original insn. In this
1402 way we preserve any clobbers etc that the insn may have had.
1403 This is of course not possible in the IS_MEM case. */
1404 if (! general_operand (a, GET_MODE (a)))
1410 tmp = gen_reg_rtx (GET_MODE (a));
1411 tmp = emit_insn (gen_rtx_SET (VOIDmode, tmp, a));
1414 goto end_seq_and_fail;
1417 a = gen_reg_rtx (GET_MODE (a));
1418 tmp = copy_rtx (insn_a);
1419 set = single_set (tmp);
1421 tmp = emit_insn (PATTERN (tmp));
1423 if (recog_memoized (tmp) < 0)
1424 goto end_seq_and_fail;
1426 if (! general_operand (b, GET_MODE (b)))
1432 tmp = gen_reg_rtx (GET_MODE (b));
1433 tmp = gen_rtx_SET (VOIDmode, tmp, b);
1436 goto end_seq_and_fail;
1439 b = gen_reg_rtx (GET_MODE (b));
1440 tmp = copy_rtx (insn_b);
1441 set = single_set (tmp);
1443 tmp = PATTERN (tmp);
1446 /* If insn to set up A clobbers any registers B depends on, try to
1447 swap insn that sets up A with the one that sets up B. If even
1448 that doesn't help, punt. */
1449 last = get_last_insn ();
1450 if (last && modified_in_p (orig_b, last))
1452 tmp = emit_insn_before (tmp, get_insns ());
1453 if (modified_in_p (orig_a, tmp))
1454 goto end_seq_and_fail;
1457 tmp = emit_insn (tmp);
1459 if (recog_memoized (tmp) < 0)
1460 goto end_seq_and_fail;
1463 target = noce_emit_cmove (if_info, x, code, XEXP (if_info->cond, 0),
1464 XEXP (if_info->cond, 1), a, b);
1467 goto end_seq_and_fail;
1469 /* If we're handling a memory for above, emit the load now. */
1472 tmp = gen_rtx_MEM (GET_MODE (if_info->x), target);
1474 /* Copy over flags as appropriate. */
1475 if (MEM_VOLATILE_P (if_info->a) || MEM_VOLATILE_P (if_info->b))
1476 MEM_VOLATILE_P (tmp) = 1;
1477 if (MEM_IN_STRUCT_P (if_info->a) && MEM_IN_STRUCT_P (if_info->b))
1478 MEM_IN_STRUCT_P (tmp) = 1;
1479 if (MEM_SCALAR_P (if_info->a) && MEM_SCALAR_P (if_info->b))
1480 MEM_SCALAR_P (tmp) = 1;
1481 if (MEM_ALIAS_SET (if_info->a) == MEM_ALIAS_SET (if_info->b))
1482 set_mem_alias_set (tmp, MEM_ALIAS_SET (if_info->a));
1484 MIN (MEM_ALIGN (if_info->a), MEM_ALIGN (if_info->b)));
1486 gcc_assert (MEM_ADDR_SPACE (if_info->a) == MEM_ADDR_SPACE (if_info->b));
1487 set_mem_addr_space (tmp, MEM_ADDR_SPACE (if_info->a));
1489 noce_emit_move_insn (if_info->x, tmp);
1491 else if (target != x)
1492 noce_emit_move_insn (x, target);
1494 tmp = end_ifcvt_sequence (if_info);
1498 emit_insn_before_setloc (tmp, if_info->jump, INSN_LOCATOR (if_info->insn_a));
1506 /* For most cases, the simplified condition we found is the best
1507 choice, but this is not the case for the min/max/abs transforms.
1508 For these we wish to know that it is A or B in the condition. */
1511 noce_get_alt_condition (struct noce_if_info *if_info, rtx target,
1514 rtx cond, set, insn;
1517 /* If target is already mentioned in the known condition, return it. */
1518 if (reg_mentioned_p (target, if_info->cond))
1520 *earliest = if_info->cond_earliest;
1521 return if_info->cond;
1524 set = pc_set (if_info->jump);
1525 cond = XEXP (SET_SRC (set), 0);
1527 = GET_CODE (XEXP (SET_SRC (set), 2)) == LABEL_REF
1528 && XEXP (XEXP (SET_SRC (set), 2), 0) == JUMP_LABEL (if_info->jump);
1529 if (if_info->then_else_reversed)
1532 /* If we're looking for a constant, try to make the conditional
1533 have that constant in it. There are two reasons why it may
1534 not have the constant we want:
1536 1. GCC may have needed to put the constant in a register, because
1537 the target can't compare directly against that constant. For
1538 this case, we look for a SET immediately before the comparison
1539 that puts a constant in that register.
1541 2. GCC may have canonicalized the conditional, for example
1542 replacing "if x < 4" with "if x <= 3". We can undo that (or
1543 make equivalent types of changes) to get the constants we need
1544 if they're off by one in the right direction. */
1546 if (CONST_INT_P (target))
1548 enum rtx_code code = GET_CODE (if_info->cond);
1549 rtx op_a = XEXP (if_info->cond, 0);
1550 rtx op_b = XEXP (if_info->cond, 1);
1553 /* First, look to see if we put a constant in a register. */
1554 prev_insn = prev_nonnote_insn (if_info->cond_earliest);
1556 && BLOCK_FOR_INSN (prev_insn)
1557 == BLOCK_FOR_INSN (if_info->cond_earliest)
1558 && INSN_P (prev_insn)
1559 && GET_CODE (PATTERN (prev_insn)) == SET)
1561 rtx src = find_reg_equal_equiv_note (prev_insn);
1563 src = SET_SRC (PATTERN (prev_insn));
1564 if (CONST_INT_P (src))
1566 if (rtx_equal_p (op_a, SET_DEST (PATTERN (prev_insn))))
1568 else if (rtx_equal_p (op_b, SET_DEST (PATTERN (prev_insn))))
1571 if (CONST_INT_P (op_a))
1576 code = swap_condition (code);
1581 /* Now, look to see if we can get the right constant by
1582 adjusting the conditional. */
1583 if (CONST_INT_P (op_b))
1585 HOST_WIDE_INT desired_val = INTVAL (target);
1586 HOST_WIDE_INT actual_val = INTVAL (op_b);
1591 if (actual_val == desired_val + 1)
1594 op_b = GEN_INT (desired_val);
1598 if (actual_val == desired_val - 1)
1601 op_b = GEN_INT (desired_val);
1605 if (actual_val == desired_val - 1)
1608 op_b = GEN_INT (desired_val);
1612 if (actual_val == desired_val + 1)
1615 op_b = GEN_INT (desired_val);
1623 /* If we made any changes, generate a new conditional that is
1624 equivalent to what we started with, but has the right
1626 if (code != GET_CODE (if_info->cond)
1627 || op_a != XEXP (if_info->cond, 0)
1628 || op_b != XEXP (if_info->cond, 1))
1630 cond = gen_rtx_fmt_ee (code, GET_MODE (cond), op_a, op_b);
1631 *earliest = if_info->cond_earliest;
1636 cond = canonicalize_condition (if_info->jump, cond, reverse,
1637 earliest, target, false, true);
1638 if (! cond || ! reg_mentioned_p (target, cond))
1641 /* We almost certainly searched back to a different place.
1642 Need to re-verify correct lifetimes. */
1644 /* X may not be mentioned in the range (cond_earliest, jump]. */
1645 for (insn = if_info->jump; insn != *earliest; insn = PREV_INSN (insn))
1646 if (INSN_P (insn) && reg_overlap_mentioned_p (if_info->x, PATTERN (insn)))
1649 /* A and B may not be modified in the range [cond_earliest, jump). */
1650 for (insn = *earliest; insn != if_info->jump; insn = NEXT_INSN (insn))
1652 && (modified_in_p (if_info->a, insn)
1653 || modified_in_p (if_info->b, insn)))
1659 /* Convert "if (a < b) x = a; else x = b;" to "x = min(a, b);", etc. */
1662 noce_try_minmax (struct noce_if_info *if_info)
1664 rtx cond, earliest, target, seq;
1665 enum rtx_code code, op;
1668 /* ??? Reject modes with NaNs or signed zeros since we don't know how
1669 they will be resolved with an SMIN/SMAX. It wouldn't be too hard
1670 to get the target to tell us... */
1671 if (HONOR_SIGNED_ZEROS (GET_MODE (if_info->x))
1672 || HONOR_NANS (GET_MODE (if_info->x)))
1675 cond = noce_get_alt_condition (if_info, if_info->a, &earliest);
1679 /* Verify the condition is of the form we expect, and canonicalize
1680 the comparison code. */
1681 code = GET_CODE (cond);
1682 if (rtx_equal_p (XEXP (cond, 0), if_info->a))
1684 if (! rtx_equal_p (XEXP (cond, 1), if_info->b))
1687 else if (rtx_equal_p (XEXP (cond, 1), if_info->a))
1689 if (! rtx_equal_p (XEXP (cond, 0), if_info->b))
1691 code = swap_condition (code);
1696 /* Determine what sort of operation this is. Note that the code is for
1697 a taken branch, so the code->operation mapping appears backwards. */
1730 target = expand_simple_binop (GET_MODE (if_info->x), op,
1731 if_info->a, if_info->b,
1732 if_info->x, unsignedp, OPTAB_WIDEN);
1738 if (target != if_info->x)
1739 noce_emit_move_insn (if_info->x, target);
1741 seq = end_ifcvt_sequence (if_info);
1745 emit_insn_before_setloc (seq, if_info->jump, INSN_LOCATOR (if_info->insn_a));
1746 if_info->cond = cond;
1747 if_info->cond_earliest = earliest;
1752 /* Convert "if (a < 0) x = -a; else x = a;" to "x = abs(a);",
1753 "if (a < 0) x = ~a; else x = a;" to "x = one_cmpl_abs(a);",
1757 noce_try_abs (struct noce_if_info *if_info)
1759 rtx cond, earliest, target, seq, a, b, c;
1761 bool one_cmpl = false;
1763 /* Reject modes with signed zeros. */
1764 if (HONOR_SIGNED_ZEROS (GET_MODE (if_info->x)))
1767 /* Recognize A and B as constituting an ABS or NABS. The canonical
1768 form is a branch around the negation, taken when the object is the
1769 first operand of a comparison against 0 that evaluates to true. */
1772 if (GET_CODE (a) == NEG && rtx_equal_p (XEXP (a, 0), b))
1774 else if (GET_CODE (b) == NEG && rtx_equal_p (XEXP (b, 0), a))
1776 c = a; a = b; b = c;
1779 else if (GET_CODE (a) == NOT && rtx_equal_p (XEXP (a, 0), b))
1784 else if (GET_CODE (b) == NOT && rtx_equal_p (XEXP (b, 0), a))
1786 c = a; a = b; b = c;
1793 cond = noce_get_alt_condition (if_info, b, &earliest);
1797 /* Verify the condition is of the form we expect. */
1798 if (rtx_equal_p (XEXP (cond, 0), b))
1800 else if (rtx_equal_p (XEXP (cond, 1), b))
1808 /* Verify that C is zero. Search one step backward for a
1809 REG_EQUAL note or a simple source if necessary. */
1812 rtx set, insn = prev_nonnote_insn (earliest);
1814 && BLOCK_FOR_INSN (insn) == BLOCK_FOR_INSN (earliest)
1815 && (set = single_set (insn))
1816 && rtx_equal_p (SET_DEST (set), c))
1818 rtx note = find_reg_equal_equiv_note (insn);
1828 && GET_CODE (XEXP (c, 0)) == SYMBOL_REF
1829 && CONSTANT_POOL_ADDRESS_P (XEXP (c, 0)))
1830 c = get_pool_constant (XEXP (c, 0));
1832 /* Work around funny ideas get_condition has wrt canonicalization.
1833 Note that these rtx constants are known to be CONST_INT, and
1834 therefore imply integer comparisons. */
1835 if (c == constm1_rtx && GET_CODE (cond) == GT)
1837 else if (c == const1_rtx && GET_CODE (cond) == LT)
1839 else if (c != CONST0_RTX (GET_MODE (b)))
1842 /* Determine what sort of operation this is. */
1843 switch (GET_CODE (cond))
1862 target = expand_one_cmpl_abs_nojump (GET_MODE (if_info->x), b,
1865 target = expand_abs_nojump (GET_MODE (if_info->x), b, if_info->x, 1);
1867 /* ??? It's a quandary whether cmove would be better here, especially
1868 for integers. Perhaps combine will clean things up. */
1869 if (target && negate)
1872 target = expand_simple_unop (GET_MODE (target), NOT, target,
1875 target = expand_simple_unop (GET_MODE (target), NEG, target,
1885 if (target != if_info->x)
1886 noce_emit_move_insn (if_info->x, target);
1888 seq = end_ifcvt_sequence (if_info);
1892 emit_insn_before_setloc (seq, if_info->jump, INSN_LOCATOR (if_info->insn_a));
1893 if_info->cond = cond;
1894 if_info->cond_earliest = earliest;
1899 /* Convert "if (m < 0) x = b; else x = 0;" to "x = (m >> C) & b;". */
1902 noce_try_sign_mask (struct noce_if_info *if_info)
1904 rtx cond, t, m, c, seq;
1905 enum machine_mode mode;
1907 bool t_unconditional;
1909 cond = if_info->cond;
1910 code = GET_CODE (cond);
1915 if (if_info->a == const0_rtx)
1917 if ((code == LT && c == const0_rtx)
1918 || (code == LE && c == constm1_rtx))
1921 else if (if_info->b == const0_rtx)
1923 if ((code == GE && c == const0_rtx)
1924 || (code == GT && c == constm1_rtx))
1928 if (! t || side_effects_p (t))
1931 /* We currently don't handle different modes. */
1932 mode = GET_MODE (t);
1933 if (GET_MODE (m) != mode)
1936 /* This is only profitable if T is unconditionally executed/evaluated in the
1937 original insn sequence or T is cheap. The former happens if B is the
1938 non-zero (T) value and if INSN_B was taken from TEST_BB, or there was no
1939 INSN_B which can happen for e.g. conditional stores to memory. For the
1940 cost computation use the block TEST_BB where the evaluation will end up
1941 after the transformation. */
1944 && (if_info->insn_b == NULL_RTX
1945 || BLOCK_FOR_INSN (if_info->insn_b) == if_info->test_bb));
1946 if (!(t_unconditional
1947 || (rtx_cost (t, SET, optimize_bb_for_speed_p (if_info->test_bb))
1948 < COSTS_N_INSNS (2))))
1952 /* Use emit_store_flag to generate "m < 0 ? -1 : 0" instead of expanding
1953 "(signed) m >> 31" directly. This benefits targets with specialized
1954 insns to obtain the signmask, but still uses ashr_optab otherwise. */
1955 m = emit_store_flag (gen_reg_rtx (mode), LT, m, const0_rtx, mode, 0, -1);
1956 t = m ? expand_binop (mode, and_optab, m, t, NULL_RTX, 0, OPTAB_DIRECT)
1965 noce_emit_move_insn (if_info->x, t);
1967 seq = end_ifcvt_sequence (if_info);
1971 emit_insn_before_setloc (seq, if_info->jump, INSN_LOCATOR (if_info->insn_a));
1976 /* Optimize away "if (x & C) x |= C" and similar bit manipulation
1980 noce_try_bitop (struct noce_if_info *if_info)
1982 rtx cond, x, a, result, seq;
1983 enum machine_mode mode;
1988 cond = if_info->cond;
1989 code = GET_CODE (cond);
1991 /* Check for no else condition. */
1992 if (! rtx_equal_p (x, if_info->b))
1995 /* Check for a suitable condition. */
1996 if (code != NE && code != EQ)
1998 if (XEXP (cond, 1) != const0_rtx)
2000 cond = XEXP (cond, 0);
2002 /* ??? We could also handle AND here. */
2003 if (GET_CODE (cond) == ZERO_EXTRACT)
2005 if (XEXP (cond, 1) != const1_rtx
2006 || !CONST_INT_P (XEXP (cond, 2))
2007 || ! rtx_equal_p (x, XEXP (cond, 0)))
2009 bitnum = INTVAL (XEXP (cond, 2));
2010 mode = GET_MODE (x);
2011 if (BITS_BIG_ENDIAN)
2012 bitnum = GET_MODE_BITSIZE (mode) - 1 - bitnum;
2013 if (bitnum < 0 || bitnum >= HOST_BITS_PER_WIDE_INT)
2020 if (GET_CODE (a) == IOR || GET_CODE (a) == XOR)
2022 /* Check for "if (X & C) x = x op C". */
2023 if (! rtx_equal_p (x, XEXP (a, 0))
2024 || !CONST_INT_P (XEXP (a, 1))
2025 || (INTVAL (XEXP (a, 1)) & GET_MODE_MASK (mode))
2026 != (unsigned HOST_WIDE_INT) 1 << bitnum)
2029 /* if ((x & C) == 0) x |= C; is transformed to x |= C. */
2030 /* if ((x & C) != 0) x |= C; is transformed to nothing. */
2031 if (GET_CODE (a) == IOR)
2032 result = (code == NE) ? a : NULL_RTX;
2033 else if (code == NE)
2035 /* if ((x & C) == 0) x ^= C; is transformed to x |= C. */
2036 result = gen_int_mode ((HOST_WIDE_INT) 1 << bitnum, mode);
2037 result = simplify_gen_binary (IOR, mode, x, result);
2041 /* if ((x & C) != 0) x ^= C; is transformed to x &= ~C. */
2042 result = gen_int_mode (~((HOST_WIDE_INT) 1 << bitnum), mode);
2043 result = simplify_gen_binary (AND, mode, x, result);
2046 else if (GET_CODE (a) == AND)
2048 /* Check for "if (X & C) x &= ~C". */
2049 if (! rtx_equal_p (x, XEXP (a, 0))
2050 || !CONST_INT_P (XEXP (a, 1))
2051 || (INTVAL (XEXP (a, 1)) & GET_MODE_MASK (mode))
2052 != (~((HOST_WIDE_INT) 1 << bitnum) & GET_MODE_MASK (mode)))
2055 /* if ((x & C) == 0) x &= ~C; is transformed to nothing. */
2056 /* if ((x & C) != 0) x &= ~C; is transformed to x &= ~C. */
2057 result = (code == EQ) ? a : NULL_RTX;
2065 noce_emit_move_insn (x, result);
2066 seq = end_ifcvt_sequence (if_info);
2070 emit_insn_before_setloc (seq, if_info->jump,
2071 INSN_LOCATOR (if_info->insn_a));
2077 /* Similar to get_condition, only the resulting condition must be
2078 valid at JUMP, instead of at EARLIEST.
2080 If THEN_ELSE_REVERSED is true, the fallthrough does not go to the
2081 THEN block of the caller, and we have to reverse the condition. */
2084 noce_get_condition (rtx jump, rtx *earliest, bool then_else_reversed)
2089 if (! any_condjump_p (jump))
2092 set = pc_set (jump);
2094 /* If this branches to JUMP_LABEL when the condition is false,
2095 reverse the condition. */
2096 reverse = (GET_CODE (XEXP (SET_SRC (set), 2)) == LABEL_REF
2097 && XEXP (XEXP (SET_SRC (set), 2), 0) == JUMP_LABEL (jump));
2099 /* We may have to reverse because the caller's if block is not canonical,
2100 i.e. the THEN block isn't the fallthrough block for the TEST block
2101 (see find_if_header). */
2102 if (then_else_reversed)
2105 /* If the condition variable is a register and is MODE_INT, accept it. */
2107 cond = XEXP (SET_SRC (set), 0);
2108 tmp = XEXP (cond, 0);
2109 if (REG_P (tmp) && GET_MODE_CLASS (GET_MODE (tmp)) == MODE_INT)
2114 cond = gen_rtx_fmt_ee (reverse_condition (GET_CODE (cond)),
2115 GET_MODE (cond), tmp, XEXP (cond, 1));
2119 /* Otherwise, fall back on canonicalize_condition to do the dirty
2120 work of manipulating MODE_CC values and COMPARE rtx codes. */
2121 return canonicalize_condition (jump, cond, reverse, earliest,
2122 NULL_RTX, false, true);
2125 /* Return true if OP is ok for if-then-else processing. */
2128 noce_operand_ok (const_rtx op)
2130 /* We special-case memories, so handle any of them with
2131 no address side effects. */
2133 return ! side_effects_p (XEXP (op, 0));
2135 if (side_effects_p (op))
2138 return ! may_trap_p (op);
2141 /* Return true if a write into MEM may trap or fault. */
2144 noce_mem_write_may_trap_or_fault_p (const_rtx mem)
2148 if (MEM_READONLY_P (mem))
2151 if (may_trap_or_fault_p (mem))
2154 addr = XEXP (mem, 0);
2156 /* Call target hook to avoid the effects of -fpic etc.... */
2157 addr = targetm.delegitimize_address (addr);
2160 switch (GET_CODE (addr))
2168 addr = XEXP (addr, 0);
2172 addr = XEXP (addr, 1);
2175 if (CONST_INT_P (XEXP (addr, 1)))
2176 addr = XEXP (addr, 0);
2183 if (SYMBOL_REF_DECL (addr)
2184 && decl_readonly_section (SYMBOL_REF_DECL (addr), 0))
2194 /* Return whether we can use store speculation for MEM. TOP_BB is the
2195 basic block above the conditional block where we are considering
2196 doing the speculative store. We look for whether MEM is set
2197 unconditionally later in the function. */
2200 noce_can_store_speculate_p (basic_block top_bb, const_rtx mem)
2202 basic_block dominator;
2204 for (dominator = get_immediate_dominator (CDI_POST_DOMINATORS, top_bb);
2206 dominator = get_immediate_dominator (CDI_POST_DOMINATORS, dominator))
2210 FOR_BB_INSNS (dominator, insn)
2212 /* If we see something that might be a memory barrier, we
2213 have to stop looking. Even if the MEM is set later in
2214 the function, we still don't want to set it
2215 unconditionally before the barrier. */
2217 && (volatile_insn_p (PATTERN (insn))
2218 || (CALL_P (insn) && (!RTL_CONST_CALL_P (insn)))))
2221 if (memory_modified_in_insn_p (mem, insn))
2223 if (modified_in_p (XEXP (mem, 0), insn))
2232 /* Given a simple IF-THEN-JOIN or IF-THEN-ELSE-JOIN block, attempt to convert
2233 it without using conditional execution. Return TRUE if we were successful
2234 at converting the block. */
2237 noce_process_if_block (struct noce_if_info *if_info)
2239 basic_block test_bb = if_info->test_bb; /* test block */
2240 basic_block then_bb = if_info->then_bb; /* THEN */
2241 basic_block else_bb = if_info->else_bb; /* ELSE or NULL */
2242 basic_block join_bb = if_info->join_bb; /* JOIN */
2243 rtx jump = if_info->jump;
2244 rtx cond = if_info->cond;
2247 rtx orig_x, x, a, b;
2249 /* We're looking for patterns of the form
2251 (1) if (...) x = a; else x = b;
2252 (2) x = b; if (...) x = a;
2253 (3) if (...) x = a; // as if with an initial x = x.
2255 The later patterns require jumps to be more expensive.
2257 ??? For future expansion, look for multiple X in such patterns. */
2259 /* Look for one of the potential sets. */
2260 insn_a = first_active_insn (then_bb);
2262 || insn_a != last_active_insn (then_bb, FALSE)
2263 || (set_a = single_set (insn_a)) == NULL_RTX)
2266 x = SET_DEST (set_a);
2267 a = SET_SRC (set_a);
2269 /* Look for the other potential set. Make sure we've got equivalent
2271 /* ??? This is overconservative. Storing to two different mems is
2272 as easy as conditionally computing the address. Storing to a
2273 single mem merely requires a scratch memory to use as one of the
2274 destination addresses; often the memory immediately below the
2275 stack pointer is available for this. */
2279 insn_b = first_active_insn (else_bb);
2281 || insn_b != last_active_insn (else_bb, FALSE)
2282 || (set_b = single_set (insn_b)) == NULL_RTX
2283 || ! rtx_equal_p (x, SET_DEST (set_b)))
2288 insn_b = prev_nonnote_insn (if_info->cond_earliest);
2289 while (insn_b && DEBUG_INSN_P (insn_b))
2290 insn_b = prev_nonnote_insn (insn_b);
2291 /* We're going to be moving the evaluation of B down from above
2292 COND_EARLIEST to JUMP. Make sure the relevant data is still
2295 || BLOCK_FOR_INSN (insn_b) != BLOCK_FOR_INSN (if_info->cond_earliest)
2296 || !NONJUMP_INSN_P (insn_b)
2297 || (set_b = single_set (insn_b)) == NULL_RTX
2298 || ! rtx_equal_p (x, SET_DEST (set_b))
2299 || ! noce_operand_ok (SET_SRC (set_b))
2300 || reg_overlap_mentioned_p (x, SET_SRC (set_b))
2301 || modified_between_p (SET_SRC (set_b), insn_b, jump)
2302 /* Likewise with X. In particular this can happen when
2303 noce_get_condition looks farther back in the instruction
2304 stream than one might expect. */
2305 || reg_overlap_mentioned_p (x, cond)
2306 || reg_overlap_mentioned_p (x, a)
2307 || modified_between_p (x, insn_b, jump))
2308 insn_b = set_b = NULL_RTX;
2311 /* If x has side effects then only the if-then-else form is safe to
2312 convert. But even in that case we would need to restore any notes
2313 (such as REG_INC) at then end. That can be tricky if
2314 noce_emit_move_insn expands to more than one insn, so disable the
2315 optimization entirely for now if there are side effects. */
2316 if (side_effects_p (x))
2319 b = (set_b ? SET_SRC (set_b) : x);
2321 /* Only operate on register destinations, and even then avoid extending
2322 the lifetime of hard registers on small register class machines. */
2325 || (SMALL_REGISTER_CLASSES
2326 && REGNO (x) < FIRST_PSEUDO_REGISTER))
2328 if (GET_MODE (x) == BLKmode)
2331 if (GET_CODE (x) == ZERO_EXTRACT
2332 && (!CONST_INT_P (XEXP (x, 1))
2333 || !CONST_INT_P (XEXP (x, 2))))
2336 x = gen_reg_rtx (GET_MODE (GET_CODE (x) == STRICT_LOW_PART
2337 ? XEXP (x, 0) : x));
2340 /* Don't operate on sources that may trap or are volatile. */
2341 if (! noce_operand_ok (a) || ! noce_operand_ok (b))
2345 /* Set up the info block for our subroutines. */
2346 if_info->insn_a = insn_a;
2347 if_info->insn_b = insn_b;
2352 /* Try optimizations in some approximation of a useful order. */
2353 /* ??? Should first look to see if X is live incoming at all. If it
2354 isn't, we don't need anything but an unconditional set. */
2356 /* Look and see if A and B are really the same. Avoid creating silly
2357 cmove constructs that no one will fix up later. */
2358 if (rtx_equal_p (a, b))
2360 /* If we have an INSN_B, we don't have to create any new rtl. Just
2361 move the instruction that we already have. If we don't have an
2362 INSN_B, that means that A == X, and we've got a noop move. In
2363 that case don't do anything and let the code below delete INSN_A. */
2364 if (insn_b && else_bb)
2368 if (else_bb && insn_b == BB_END (else_bb))
2369 BB_END (else_bb) = PREV_INSN (insn_b);
2370 reorder_insns (insn_b, insn_b, PREV_INSN (jump));
2372 /* If there was a REG_EQUAL note, delete it since it may have been
2373 true due to this insn being after a jump. */
2374 if ((note = find_reg_note (insn_b, REG_EQUAL, NULL_RTX)) != 0)
2375 remove_note (insn_b, note);
2379 /* If we have "x = b; if (...) x = a;", and x has side-effects, then
2380 x must be executed twice. */
2381 else if (insn_b && side_effects_p (orig_x))
2388 if (!set_b && MEM_P (orig_x))
2390 /* Disallow the "if (...) x = a;" form (implicit "else x = x;")
2391 for optimizations if writing to x may trap or fault,
2392 i.e. it's a memory other than a static var or a stack slot,
2393 is misaligned on strict aligned machines or is read-only. If
2394 x is a read-only memory, then the program is valid only if we
2395 avoid the store into it. If there are stores on both the
2396 THEN and ELSE arms, then we can go ahead with the conversion;
2397 either the program is broken, or the condition is always
2398 false such that the other memory is selected. */
2399 if (noce_mem_write_may_trap_or_fault_p (orig_x))
2402 /* Avoid store speculation: given "if (...) x = a" where x is a
2403 MEM, we only want to do the store if x is always set
2404 somewhere in the function. This avoids cases like
2405 if (pthread_mutex_trylock(mutex))
2407 where we only want global_variable to be changed if the mutex
2408 is held. FIXME: This should ideally be expressed directly in
2410 if (!noce_can_store_speculate_p (test_bb, orig_x))
2414 if (noce_try_move (if_info))
2416 if (noce_try_store_flag (if_info))
2418 if (noce_try_bitop (if_info))
2420 if (noce_try_minmax (if_info))
2422 if (noce_try_abs (if_info))
2424 if (HAVE_conditional_move
2425 && noce_try_cmove (if_info))
2427 if (! targetm.have_conditional_execution ())
2429 if (noce_try_store_flag_constants (if_info))
2431 if (noce_try_addcc (if_info))
2433 if (noce_try_store_flag_mask (if_info))
2435 if (HAVE_conditional_move
2436 && noce_try_cmove_arith (if_info))
2438 if (noce_try_sign_mask (if_info))
2442 if (!else_bb && set_b)
2444 insn_b = set_b = NULL_RTX;
2453 /* If we used a temporary, fix it up now. */
2459 noce_emit_move_insn (orig_x, x);
2461 set_used_flags (orig_x);
2462 unshare_all_rtl_in_chain (seq);
2465 emit_insn_before_setloc (seq, BB_END (test_bb), INSN_LOCATOR (insn_a));
2468 /* The original THEN and ELSE blocks may now be removed. The test block
2469 must now jump to the join block. If the test block and the join block
2470 can be merged, do so. */
2473 delete_basic_block (else_bb);
2477 remove_edge (find_edge (test_bb, join_bb));
2479 remove_edge (find_edge (then_bb, join_bb));
2480 redirect_edge_and_branch_force (single_succ_edge (test_bb), join_bb);
2481 delete_basic_block (then_bb);
2484 if (can_merge_blocks_p (test_bb, join_bb))
2486 merge_blocks (test_bb, join_bb);
2490 num_updated_if_blocks++;
2494 /* Check whether a block is suitable for conditional move conversion.
2495 Every insn must be a simple set of a register to a constant or a
2496 register. For each assignment, store the value in the array VALS,
2497 indexed by register number, then store the register number in
2498 REGS. COND is the condition we will test. */
2501 check_cond_move_block (basic_block bb, rtx *vals, VEC (int, heap) **regs, rtx cond)
2505 /* We can only handle simple jumps at the end of the basic block.
2506 It is almost impossible to update the CFG otherwise. */
2508 if (JUMP_P (insn) && !onlyjump_p (insn))
2511 FOR_BB_INSNS (bb, insn)
2515 if (!NONDEBUG_INSN_P (insn) || JUMP_P (insn))
2517 set = single_set (insn);
2521 dest = SET_DEST (set);
2522 src = SET_SRC (set);
2524 || (SMALL_REGISTER_CLASSES && HARD_REGISTER_P (dest)))
2527 if (!CONSTANT_P (src) && !register_operand (src, VOIDmode))
2530 if (side_effects_p (src) || side_effects_p (dest))
2533 if (may_trap_p (src) || may_trap_p (dest))
2536 /* Don't try to handle this if the source register was
2537 modified earlier in the block. */
2539 && vals[REGNO (src)] != NULL)
2540 || (GET_CODE (src) == SUBREG && REG_P (SUBREG_REG (src))
2541 && vals[REGNO (SUBREG_REG (src))] != NULL))
2544 /* Don't try to handle this if the destination register was
2545 modified earlier in the block. */
2546 if (vals[REGNO (dest)] != NULL)
2549 /* Don't try to handle this if the condition uses the
2550 destination register. */
2551 if (reg_overlap_mentioned_p (dest, cond))
2554 /* Don't try to handle this if the source register is modified
2555 later in the block. */
2556 if (!CONSTANT_P (src)
2557 && modified_between_p (src, insn, NEXT_INSN (BB_END (bb))))
2560 vals[REGNO (dest)] = src;
2562 VEC_safe_push (int, heap, *regs, REGNO (dest));
2568 /* Given a basic block BB suitable for conditional move conversion,
2569 a condition COND, and arrays THEN_VALS and ELSE_VALS containing the
2570 register values depending on COND, emit the insns in the block as
2571 conditional moves. If ELSE_BLOCK is true, THEN_BB was already
2572 processed. The caller has started a sequence for the conversion.
2573 Return true if successful, false if something goes wrong. */
2576 cond_move_convert_if_block (struct noce_if_info *if_infop,
2577 basic_block bb, rtx cond,
2578 rtx *then_vals, rtx *else_vals,
2582 rtx insn, cond_arg0, cond_arg1;
2584 code = GET_CODE (cond);
2585 cond_arg0 = XEXP (cond, 0);
2586 cond_arg1 = XEXP (cond, 1);
2588 FOR_BB_INSNS (bb, insn)
2590 rtx set, target, dest, t, e;
2593 /* ??? Maybe emit conditional debug insn? */
2594 if (!NONDEBUG_INSN_P (insn) || JUMP_P (insn))
2596 set = single_set (insn);
2597 gcc_assert (set && REG_P (SET_DEST (set)));
2599 dest = SET_DEST (set);
2600 regno = REGNO (dest);
2602 t = then_vals[regno];
2603 e = else_vals[regno];
2607 /* If this register was set in the then block, we already
2608 handled this case there. */
2621 target = noce_emit_cmove (if_infop, dest, code, cond_arg0, cond_arg1,
2627 noce_emit_move_insn (dest, target);
2633 /* Given a simple IF-THEN-JOIN or IF-THEN-ELSE-JOIN block, attempt to convert
2634 it using only conditional moves. Return TRUE if we were successful at
2635 converting the block. */
2638 cond_move_process_if_block (struct noce_if_info *if_info)
2640 basic_block test_bb = if_info->test_bb;
2641 basic_block then_bb = if_info->then_bb;
2642 basic_block else_bb = if_info->else_bb;
2643 basic_block join_bb = if_info->join_bb;
2644 rtx jump = if_info->jump;
2645 rtx cond = if_info->cond;
2647 int max_reg, size, c, reg;
2650 VEC (int, heap) *then_regs = NULL;
2651 VEC (int, heap) *else_regs = NULL;
2654 /* Build a mapping for each block to the value used for each
2656 max_reg = max_reg_num ();
2657 size = (max_reg + 1) * sizeof (rtx);
2658 then_vals = (rtx *) alloca (size);
2659 else_vals = (rtx *) alloca (size);
2660 memset (then_vals, 0, size);
2661 memset (else_vals, 0, size);
2663 /* Make sure the blocks are suitable. */
2664 if (!check_cond_move_block (then_bb, then_vals, &then_regs, cond)
2665 || (else_bb && !check_cond_move_block (else_bb, else_vals, &else_regs, cond)))
2667 VEC_free (int, heap, then_regs);
2668 VEC_free (int, heap, else_regs);
2672 /* Make sure the blocks can be used together. If the same register
2673 is set in both blocks, and is not set to a constant in both
2674 cases, then both blocks must set it to the same register. We
2675 have already verified that if it is set to a register, that the
2676 source register does not change after the assignment. Also count
2677 the number of registers set in only one of the blocks. */
2679 for (i = 0; VEC_iterate (int, then_regs, i, reg); i++)
2681 if (!then_vals[reg] && !else_vals[reg])
2684 if (!else_vals[reg])
2688 if (!CONSTANT_P (then_vals[reg])
2689 && !CONSTANT_P (else_vals[reg])
2690 && !rtx_equal_p (then_vals[reg], else_vals[reg]))
2692 VEC_free (int, heap, then_regs);
2693 VEC_free (int, heap, else_regs);
2699 /* Finish off c for MAX_CONDITIONAL_EXECUTE. */
2700 for (i = 0; VEC_iterate (int, else_regs, i, reg); ++i)
2701 if (!then_vals[reg])
2704 /* Make sure it is reasonable to convert this block. What matters
2705 is the number of assignments currently made in only one of the
2706 branches, since if we convert we are going to always execute
2708 if (c > MAX_CONDITIONAL_EXECUTE)
2710 VEC_free (int, heap, then_regs);
2711 VEC_free (int, heap, else_regs);
2715 /* Try to emit the conditional moves. First do the then block,
2716 then do anything left in the else blocks. */
2718 if (!cond_move_convert_if_block (if_info, then_bb, cond,
2719 then_vals, else_vals, false)
2721 && !cond_move_convert_if_block (if_info, else_bb, cond,
2722 then_vals, else_vals, true)))
2725 VEC_free (int, heap, then_regs);
2726 VEC_free (int, heap, else_regs);
2729 seq = end_ifcvt_sequence (if_info);
2732 VEC_free (int, heap, then_regs);
2733 VEC_free (int, heap, else_regs);
2737 loc_insn = first_active_insn (then_bb);
2740 loc_insn = first_active_insn (else_bb);
2741 gcc_assert (loc_insn);
2743 emit_insn_before_setloc (seq, jump, INSN_LOCATOR (loc_insn));
2747 delete_basic_block (else_bb);
2751 remove_edge (find_edge (test_bb, join_bb));
2753 remove_edge (find_edge (then_bb, join_bb));
2754 redirect_edge_and_branch_force (single_succ_edge (test_bb), join_bb);
2755 delete_basic_block (then_bb);
2758 if (can_merge_blocks_p (test_bb, join_bb))
2760 merge_blocks (test_bb, join_bb);
2764 num_updated_if_blocks++;
2766 VEC_free (int, heap, then_regs);
2767 VEC_free (int, heap, else_regs);
2772 /* Determine if a given basic block heads a simple IF-THEN-JOIN or an
2773 IF-THEN-ELSE-JOIN block.
2775 If so, we'll try to convert the insns to not require the branch,
2776 using only transformations that do not require conditional execution.
2778 Return TRUE if we were successful at converting the block. */
2781 noce_find_if_block (basic_block test_bb,
2782 edge then_edge, edge else_edge,
2785 basic_block then_bb, else_bb, join_bb;
2786 bool then_else_reversed = false;
2789 struct noce_if_info if_info;
2791 /* We only ever should get here before reload. */
2792 gcc_assert (!reload_completed);
2794 /* Recognize an IF-THEN-ELSE-JOIN block. */
2795 if (single_pred_p (then_edge->dest)
2796 && single_succ_p (then_edge->dest)
2797 && single_pred_p (else_edge->dest)
2798 && single_succ_p (else_edge->dest)
2799 && single_succ (then_edge->dest) == single_succ (else_edge->dest))
2801 then_bb = then_edge->dest;
2802 else_bb = else_edge->dest;
2803 join_bb = single_succ (then_bb);
2805 /* Recognize an IF-THEN-JOIN block. */
2806 else if (single_pred_p (then_edge->dest)
2807 && single_succ_p (then_edge->dest)
2808 && single_succ (then_edge->dest) == else_edge->dest)
2810 then_bb = then_edge->dest;
2811 else_bb = NULL_BLOCK;
2812 join_bb = else_edge->dest;
2814 /* Recognize an IF-ELSE-JOIN block. We can have those because the order
2815 of basic blocks in cfglayout mode does not matter, so the fallthrough
2816 edge can go to any basic block (and not just to bb->next_bb, like in
2818 else if (single_pred_p (else_edge->dest)
2819 && single_succ_p (else_edge->dest)
2820 && single_succ (else_edge->dest) == then_edge->dest)
2822 /* The noce transformations do not apply to IF-ELSE-JOIN blocks.
2823 To make this work, we have to invert the THEN and ELSE blocks
2824 and reverse the jump condition. */
2825 then_bb = else_edge->dest;
2826 else_bb = NULL_BLOCK;
2827 join_bb = single_succ (then_bb);
2828 then_else_reversed = true;
2831 /* Not a form we can handle. */
2834 /* The edges of the THEN and ELSE blocks cannot have complex edges. */
2835 if (single_succ_edge (then_bb)->flags & EDGE_COMPLEX)
2838 && single_succ_edge (else_bb)->flags & EDGE_COMPLEX)
2841 num_possible_if_blocks++;
2846 "\nIF-THEN%s-JOIN block found, pass %d, test %d, then %d",
2847 (else_bb) ? "-ELSE" : "",
2848 pass, test_bb->index, then_bb->index);
2851 fprintf (dump_file, ", else %d", else_bb->index);
2853 fprintf (dump_file, ", join %d\n", join_bb->index);
2856 /* If the conditional jump is more than just a conditional
2857 jump, then we can not do if-conversion on this block. */
2858 jump = BB_END (test_bb);
2859 if (! onlyjump_p (jump))
2862 /* If this is not a standard conditional jump, we can't parse it. */
2863 cond = noce_get_condition (jump,
2865 then_else_reversed);
2869 /* We must be comparing objects whose modes imply the size. */
2870 if (GET_MODE (XEXP (cond, 0)) == BLKmode)
2873 /* Initialize an IF_INFO struct to pass around. */
2874 memset (&if_info, 0, sizeof if_info);
2875 if_info.test_bb = test_bb;
2876 if_info.then_bb = then_bb;
2877 if_info.else_bb = else_bb;
2878 if_info.join_bb = join_bb;
2879 if_info.cond = cond;
2880 if_info.cond_earliest = cond_earliest;
2881 if_info.jump = jump;
2882 if_info.then_else_reversed = then_else_reversed;
2883 if_info.branch_cost = BRANCH_COST (optimize_bb_for_speed_p (test_bb),
2884 predictable_edge_p (then_edge));
2886 /* Do the real work. */
2888 if (noce_process_if_block (&if_info))
2891 if (HAVE_conditional_move
2892 && cond_move_process_if_block (&if_info))
2899 /* Merge the blocks and mark for local life update. */
2902 merge_if_block (struct ce_if_block * ce_info)
2904 basic_block test_bb = ce_info->test_bb; /* last test block */
2905 basic_block then_bb = ce_info->then_bb; /* THEN */
2906 basic_block else_bb = ce_info->else_bb; /* ELSE or NULL */
2907 basic_block join_bb = ce_info->join_bb; /* join block */
2908 basic_block combo_bb;
2910 /* All block merging is done into the lower block numbers. */
2913 df_set_bb_dirty (test_bb);
2915 /* Merge any basic blocks to handle && and || subtests. Each of
2916 the blocks are on the fallthru path from the predecessor block. */
2917 if (ce_info->num_multiple_test_blocks > 0)
2919 basic_block bb = test_bb;
2920 basic_block last_test_bb = ce_info->last_test_bb;
2921 basic_block fallthru = block_fallthru (bb);
2926 fallthru = block_fallthru (bb);
2927 merge_blocks (combo_bb, bb);
2930 while (bb != last_test_bb);
2933 /* Merge TEST block into THEN block. Normally the THEN block won't have a
2934 label, but it might if there were || tests. That label's count should be
2935 zero, and it normally should be removed. */
2939 merge_blocks (combo_bb, then_bb);
2943 /* The ELSE block, if it existed, had a label. That label count
2944 will almost always be zero, but odd things can happen when labels
2945 get their addresses taken. */
2948 merge_blocks (combo_bb, else_bb);
2952 /* If there was no join block reported, that means it was not adjacent
2953 to the others, and so we cannot merge them. */
2957 rtx last = BB_END (combo_bb);
2959 /* The outgoing edge for the current COMBO block should already
2960 be correct. Verify this. */
2961 if (EDGE_COUNT (combo_bb->succs) == 0)
2962 gcc_assert (find_reg_note (last, REG_NORETURN, NULL)
2963 || (NONJUMP_INSN_P (last)
2964 && GET_CODE (PATTERN (last)) == TRAP_IF
2965 && (TRAP_CONDITION (PATTERN (last))
2966 == const_true_rtx)));
2969 /* There should still be something at the end of the THEN or ELSE
2970 blocks taking us to our final destination. */
2971 gcc_assert (JUMP_P (last)
2972 || (EDGE_SUCC (combo_bb, 0)->dest == EXIT_BLOCK_PTR
2974 && SIBLING_CALL_P (last))
2975 || ((EDGE_SUCC (combo_bb, 0)->flags & EDGE_EH)
2976 && can_throw_internal (last)));
2979 /* The JOIN block may have had quite a number of other predecessors too.
2980 Since we've already merged the TEST, THEN and ELSE blocks, we should
2981 have only one remaining edge from our if-then-else diamond. If there
2982 is more than one remaining edge, it must come from elsewhere. There
2983 may be zero incoming edges if the THEN block didn't actually join
2984 back up (as with a call to a non-return function). */
2985 else if (EDGE_COUNT (join_bb->preds) < 2
2986 && join_bb != EXIT_BLOCK_PTR)
2988 /* We can merge the JOIN cleanly and update the dataflow try
2989 again on this pass.*/
2990 merge_blocks (combo_bb, join_bb);
2995 /* We cannot merge the JOIN. */
2997 /* The outgoing edge for the current COMBO block should already
2998 be correct. Verify this. */
2999 gcc_assert (single_succ_p (combo_bb)
3000 && single_succ (combo_bb) == join_bb);
3002 /* Remove the jump and cruft from the end of the COMBO block. */
3003 if (join_bb != EXIT_BLOCK_PTR)
3004 tidy_fallthru_edge (single_succ_edge (combo_bb));
3007 num_updated_if_blocks++;
3010 /* Find a block ending in a simple IF condition and try to transform it
3011 in some way. When converting a multi-block condition, put the new code
3012 in the first such block and delete the rest. Return a pointer to this
3013 first block if some transformation was done. Return NULL otherwise. */
3016 find_if_header (basic_block test_bb, int pass)
3018 ce_if_block_t ce_info;
3022 /* The kind of block we're looking for has exactly two successors. */
3023 if (EDGE_COUNT (test_bb->succs) != 2)
3026 then_edge = EDGE_SUCC (test_bb, 0);
3027 else_edge = EDGE_SUCC (test_bb, 1);
3029 if (df_get_bb_dirty (then_edge->dest))
3031 if (df_get_bb_dirty (else_edge->dest))
3034 /* Neither edge should be abnormal. */
3035 if ((then_edge->flags & EDGE_COMPLEX)
3036 || (else_edge->flags & EDGE_COMPLEX))
3039 /* Nor exit the loop. */
3040 if ((then_edge->flags & EDGE_LOOP_EXIT)
3041 || (else_edge->flags & EDGE_LOOP_EXIT))
3044 /* The THEN edge is canonically the one that falls through. */
3045 if (then_edge->flags & EDGE_FALLTHRU)
3047 else if (else_edge->flags & EDGE_FALLTHRU)
3050 else_edge = then_edge;
3054 /* Otherwise this must be a multiway branch of some sort. */
3057 memset (&ce_info, '\0', sizeof (ce_info));
3058 ce_info.test_bb = test_bb;
3059 ce_info.then_bb = then_edge->dest;
3060 ce_info.else_bb = else_edge->dest;
3061 ce_info.pass = pass;
3063 #ifdef IFCVT_INIT_EXTRA_FIELDS
3064 IFCVT_INIT_EXTRA_FIELDS (&ce_info);
3067 if (! reload_completed
3068 && noce_find_if_block (test_bb, then_edge, else_edge, pass))
3071 if (targetm.have_conditional_execution () && reload_completed
3072 && cond_exec_find_if_block (&ce_info))
3076 && optab_handler (ctrap_optab, word_mode)->insn_code != CODE_FOR_nothing
3077 && find_cond_trap (test_bb, then_edge, else_edge))
3080 if (dom_info_state (CDI_POST_DOMINATORS) >= DOM_NO_FAST_QUERY
3081 && (! targetm.have_conditional_execution () || reload_completed))
3083 if (find_if_case_1 (test_bb, then_edge, else_edge))
3085 if (find_if_case_2 (test_bb, then_edge, else_edge))
3093 fprintf (dump_file, "Conversion succeeded on pass %d.\n", pass);
3094 /* Set this so we continue looking. */
3095 cond_exec_changed_p = TRUE;
3096 return ce_info.test_bb;
3099 /* Return true if a block has two edges, one of which falls through to the next
3100 block, and the other jumps to a specific block, so that we can tell if the
3101 block is part of an && test or an || test. Returns either -1 or the number
3102 of non-note, non-jump, non-USE/CLOBBER insns in the block. */
3105 block_jumps_and_fallthru_p (basic_block cur_bb, basic_block target_bb)
3108 int fallthru_p = FALSE;
3115 if (!cur_bb || !target_bb)
3118 /* If no edges, obviously it doesn't jump or fallthru. */
3119 if (EDGE_COUNT (cur_bb->succs) == 0)
3122 FOR_EACH_EDGE (cur_edge, ei, cur_bb->succs)
3124 if (cur_edge->flags & EDGE_COMPLEX)
3125 /* Anything complex isn't what we want. */
3128 else if (cur_edge->flags & EDGE_FALLTHRU)
3131 else if (cur_edge->dest == target_bb)
3138 if ((jump_p & fallthru_p) == 0)
3141 /* Don't allow calls in the block, since this is used to group && and ||
3142 together for conditional execution support. ??? we should support
3143 conditional execution support across calls for IA-64 some day, but
3144 for now it makes the code simpler. */
3145 end = BB_END (cur_bb);
3146 insn = BB_HEAD (cur_bb);
3148 while (insn != NULL_RTX)
3155 && !DEBUG_INSN_P (insn)
3156 && GET_CODE (PATTERN (insn)) != USE
3157 && GET_CODE (PATTERN (insn)) != CLOBBER)
3163 insn = NEXT_INSN (insn);
3169 /* Determine if a given basic block heads a simple IF-THEN or IF-THEN-ELSE
3170 block. If so, we'll try to convert the insns to not require the branch.
3171 Return TRUE if we were successful at converting the block. */
3174 cond_exec_find_if_block (struct ce_if_block * ce_info)
3176 basic_block test_bb = ce_info->test_bb;
3177 basic_block then_bb = ce_info->then_bb;
3178 basic_block else_bb = ce_info->else_bb;
3179 basic_block join_bb = NULL_BLOCK;
3184 ce_info->last_test_bb = test_bb;
3186 /* We only ever should get here after reload,
3187 and only if we have conditional execution. */
3188 gcc_assert (targetm.have_conditional_execution () && reload_completed);
3190 /* Discover if any fall through predecessors of the current test basic block
3191 were && tests (which jump to the else block) or || tests (which jump to
3193 if (single_pred_p (test_bb)
3194 && single_pred_edge (test_bb)->flags == EDGE_FALLTHRU)
3196 basic_block bb = single_pred (test_bb);
3197 basic_block target_bb;
3198 int max_insns = MAX_CONDITIONAL_EXECUTE;
3201 /* Determine if the preceding block is an && or || block. */
3202 if ((n_insns = block_jumps_and_fallthru_p (bb, else_bb)) >= 0)
3204 ce_info->and_and_p = TRUE;
3205 target_bb = else_bb;
3207 else if ((n_insns = block_jumps_and_fallthru_p (bb, then_bb)) >= 0)
3209 ce_info->and_and_p = FALSE;
3210 target_bb = then_bb;
3213 target_bb = NULL_BLOCK;
3215 if (target_bb && n_insns <= max_insns)
3217 int total_insns = 0;
3220 ce_info->last_test_bb = test_bb;
3222 /* Found at least one && or || block, look for more. */
3225 ce_info->test_bb = test_bb = bb;
3226 total_insns += n_insns;
3229 if (!single_pred_p (bb))
3232 bb = single_pred (bb);
3233 n_insns = block_jumps_and_fallthru_p (bb, target_bb);
3235 while (n_insns >= 0 && (total_insns + n_insns) <= max_insns);
3237 ce_info->num_multiple_test_blocks = blocks;
3238 ce_info->num_multiple_test_insns = total_insns;
3240 if (ce_info->and_and_p)
3241 ce_info->num_and_and_blocks = blocks;
3243 ce_info->num_or_or_blocks = blocks;
3247 /* The THEN block of an IF-THEN combo must have exactly one predecessor,
3248 other than any || blocks which jump to the THEN block. */
3249 if ((EDGE_COUNT (then_bb->preds) - ce_info->num_or_or_blocks) != 1)
3252 /* The edges of the THEN and ELSE blocks cannot have complex edges. */
3253 FOR_EACH_EDGE (cur_edge, ei, then_bb->preds)
3255 if (cur_edge->flags & EDGE_COMPLEX)
3259 FOR_EACH_EDGE (cur_edge, ei, else_bb->preds)
3261 if (cur_edge->flags & EDGE_COMPLEX)
3265 /* The THEN block of an IF-THEN combo must have zero or one successors. */
3266 if (EDGE_COUNT (then_bb->succs) > 0
3267 && (!single_succ_p (then_bb)
3268 || (single_succ_edge (then_bb)->flags & EDGE_COMPLEX)
3269 || (epilogue_completed && tablejump_p (BB_END (then_bb), NULL, NULL))))
3272 /* If the THEN block has no successors, conditional execution can still
3273 make a conditional call. Don't do this unless the ELSE block has
3274 only one incoming edge -- the CFG manipulation is too ugly otherwise.
3275 Check for the last insn of the THEN block being an indirect jump, which
3276 is listed as not having any successors, but confuses the rest of the CE
3277 code processing. ??? we should fix this in the future. */
3278 if (EDGE_COUNT (then_bb->succs) == 0)
3280 if (single_pred_p (else_bb))
3282 rtx last_insn = BB_END (then_bb);
3285 && NOTE_P (last_insn)
3286 && last_insn != BB_HEAD (then_bb))
3287 last_insn = PREV_INSN (last_insn);
3290 && JUMP_P (last_insn)
3291 && ! simplejump_p (last_insn))
3295 else_bb = NULL_BLOCK;
3301 /* If the THEN block's successor is the other edge out of the TEST block,
3302 then we have an IF-THEN combo without an ELSE. */
3303 else if (single_succ (then_bb) == else_bb)
3306 else_bb = NULL_BLOCK;
3309 /* If the THEN and ELSE block meet in a subsequent block, and the ELSE
3310 has exactly one predecessor and one successor, and the outgoing edge
3311 is not complex, then we have an IF-THEN-ELSE combo. */
3312 else if (single_succ_p (else_bb)
3313 && single_succ (then_bb) == single_succ (else_bb)
3314 && single_pred_p (else_bb)
3315 && ! (single_succ_edge (else_bb)->flags & EDGE_COMPLEX)
3316 && ! (epilogue_completed && tablejump_p (BB_END (else_bb), NULL, NULL)))
3317 join_bb = single_succ (else_bb);
3319 /* Otherwise it is not an IF-THEN or IF-THEN-ELSE combination. */
3323 num_possible_if_blocks++;
3328 "\nIF-THEN%s block found, pass %d, start block %d "
3329 "[insn %d], then %d [%d]",
3330 (else_bb) ? "-ELSE" : "",
3333 BB_HEAD (test_bb) ? (int)INSN_UID (BB_HEAD (test_bb)) : -1,
3335 BB_HEAD (then_bb) ? (int)INSN_UID (BB_HEAD (then_bb)) : -1);
3338 fprintf (dump_file, ", else %d [%d]",
3340 BB_HEAD (else_bb) ? (int)INSN_UID (BB_HEAD (else_bb)) : -1);
3342 fprintf (dump_file, ", join %d [%d]",
3344 BB_HEAD (join_bb) ? (int)INSN_UID (BB_HEAD (join_bb)) : -1);
3346 if (ce_info->num_multiple_test_blocks > 0)
3347 fprintf (dump_file, ", %d %s block%s last test %d [%d]",
3348 ce_info->num_multiple_test_blocks,
3349 (ce_info->and_and_p) ? "&&" : "||",
3350 (ce_info->num_multiple_test_blocks == 1) ? "" : "s",
3351 ce_info->last_test_bb->index,
3352 ((BB_HEAD (ce_info->last_test_bb))
3353 ? (int)INSN_UID (BB_HEAD (ce_info->last_test_bb))
3356 fputc ('\n', dump_file);
3359 /* Make sure IF, THEN, and ELSE, blocks are adjacent. Actually, we get the
3360 first condition for free, since we've already asserted that there's a
3361 fallthru edge from IF to THEN. Likewise for the && and || blocks, since
3362 we checked the FALLTHRU flag, those are already adjacent to the last IF
3364 /* ??? As an enhancement, move the ELSE block. Have to deal with
3365 BLOCK notes, if by no other means than backing out the merge if they
3366 exist. Sticky enough I don't want to think about it now. */
3368 if (else_bb && (next = next->next_bb) != else_bb)
3370 if ((next = next->next_bb) != join_bb && join_bb != EXIT_BLOCK_PTR)
3378 /* Do the real work. */
3380 ce_info->else_bb = else_bb;
3381 ce_info->join_bb = join_bb;
3383 /* If we have && and || tests, try to first handle combining the && and ||
3384 tests into the conditional code, and if that fails, go back and handle
3385 it without the && and ||, which at present handles the && case if there
3386 was no ELSE block. */
3387 if (cond_exec_process_if_block (ce_info, TRUE))
3390 if (ce_info->num_multiple_test_blocks)
3394 if (cond_exec_process_if_block (ce_info, FALSE))
3401 /* Convert a branch over a trap, or a branch
3402 to a trap, into a conditional trap. */
3405 find_cond_trap (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;
3409 basic_block other_bb, trap_bb;
3410 rtx trap, jump, cond, cond_earliest, seq;
3413 /* Locate the block with the trap instruction. */
3414 /* ??? While we look for no successors, we really ought to allow
3415 EH successors. Need to fix merge_if_block for that to work. */
3416 if ((trap = block_has_only_trap (then_bb)) != NULL)
3417 trap_bb = then_bb, other_bb = else_bb;
3418 else if ((trap = block_has_only_trap (else_bb)) != NULL)
3419 trap_bb = else_bb, other_bb = then_bb;
3425 fprintf (dump_file, "\nTRAP-IF block found, start %d, trap %d\n",
3426 test_bb->index, trap_bb->index);
3429 /* If this is not a standard conditional jump, we can't parse it. */
3430 jump = BB_END (test_bb);
3431 cond = noce_get_condition (jump, &cond_earliest, false);
3435 /* If the conditional jump is more than just a conditional jump, then
3436 we can not do if-conversion on this block. */
3437 if (! onlyjump_p (jump))
3440 /* We must be comparing objects whose modes imply the size. */
3441 if (GET_MODE (XEXP (cond, 0)) == BLKmode)
3444 /* Reverse the comparison code, if necessary. */
3445 code = GET_CODE (cond);
3446 if (then_bb == trap_bb)
3448 code = reversed_comparison_code (cond, jump);
3449 if (code == UNKNOWN)
3453 /* Attempt to generate the conditional trap. */
3454 seq = gen_cond_trap (code, copy_rtx (XEXP (cond, 0)),
3455 copy_rtx (XEXP (cond, 1)),
3456 TRAP_CODE (PATTERN (trap)));
3460 /* Emit the new insns before cond_earliest. */
3461 emit_insn_before_setloc (seq, cond_earliest, INSN_LOCATOR (trap));
3463 /* Delete the trap block if possible. */
3464 remove_edge (trap_bb == then_bb ? then_edge : else_edge);
3465 df_set_bb_dirty (test_bb);
3466 df_set_bb_dirty (then_bb);
3467 df_set_bb_dirty (else_bb);
3469 if (EDGE_COUNT (trap_bb->preds) == 0)
3471 delete_basic_block (trap_bb);
3475 /* Wire together the blocks again. */
3476 if (current_ir_type () == IR_RTL_CFGLAYOUT)
3477 single_succ_edge (test_bb)->flags |= EDGE_FALLTHRU;
3482 lab = JUMP_LABEL (jump);
3483 newjump = emit_jump_insn_after (gen_jump (lab), jump);
3484 LABEL_NUSES (lab) += 1;
3485 JUMP_LABEL (newjump) = lab;
3486 emit_barrier_after (newjump);
3490 if (can_merge_blocks_p (test_bb, other_bb))
3492 merge_blocks (test_bb, other_bb);
3496 num_updated_if_blocks++;
3500 /* Subroutine of find_cond_trap: if BB contains only a trap insn,
3504 block_has_only_trap (basic_block bb)
3508 /* We're not the exit block. */
3509 if (bb == EXIT_BLOCK_PTR)
3512 /* The block must have no successors. */
3513 if (EDGE_COUNT (bb->succs) > 0)
3516 /* The only instruction in the THEN block must be the trap. */
3517 trap = first_active_insn (bb);
3518 if (! (trap == BB_END (bb)
3519 && GET_CODE (PATTERN (trap)) == TRAP_IF
3520 && TRAP_CONDITION (PATTERN (trap)) == const_true_rtx))
3526 /* Look for IF-THEN-ELSE cases in which one of THEN or ELSE is
3527 transformable, but not necessarily the other. There need be no
3530 Return TRUE if we were successful at converting the block.
3532 Cases we'd like to look at:
3535 if (test) goto over; // x not live
3543 if (! test) goto label;
3546 if (test) goto E; // x not live
3560 (3) // This one's really only interesting for targets that can do
3561 // multiway branching, e.g. IA-64 BBB bundles. For other targets
3562 // it results in multiple branches on a cache line, which often
3563 // does not sit well with predictors.
3565 if (test1) goto E; // predicted not taken
3581 (A) Don't do (2) if the branch is predicted against the block we're
3582 eliminating. Do it anyway if we can eliminate a branch; this requires
3583 that the sole successor of the eliminated block postdominate the other
3586 (B) With CE, on (3) we can steal from both sides of the if, creating
3595 Again, this is most useful if J postdominates.
3597 (C) CE substitutes for helpful life information.
3599 (D) These heuristics need a lot of work. */
3601 /* Tests for case 1 above. */
3604 find_if_case_1 (basic_block test_bb, edge then_edge, edge else_edge)
3606 basic_block then_bb = then_edge->dest;
3607 basic_block else_bb = else_edge->dest;
3611 /* If we are partitioning hot/cold basic blocks, we don't want to
3612 mess up unconditional or indirect jumps that cross between hot
3615 Basic block partitioning may result in some jumps that appear to
3616 be optimizable (or blocks that appear to be mergeable), but which really
3617 must be left untouched (they are required to make it safely across
3618 partition boundaries). See the comments at the top of
3619 bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */
3621 if ((BB_END (then_bb)
3622 && find_reg_note (BB_END (then_bb), REG_CROSSING_JUMP, NULL_RTX))
3623 || (BB_END (test_bb)
3624 && find_reg_note (BB_END (test_bb), REG_CROSSING_JUMP, NULL_RTX))
3625 || (BB_END (else_bb)
3626 && find_reg_note (BB_END (else_bb), REG_CROSSING_JUMP,
3630 /* THEN has one successor. */
3631 if (!single_succ_p (then_bb))
3634 /* THEN does not fall through, but is not strange either. */
3635 if (single_succ_edge (then_bb)->flags & (EDGE_COMPLEX | EDGE_FALLTHRU))
3638 /* THEN has one predecessor. */
3639 if (!single_pred_p (then_bb))
3642 /* THEN must do something. */
3643 if (forwarder_block_p (then_bb))
3646 num_possible_if_blocks++;
3649 "\nIF-CASE-1 found, start %d, then %d\n",
3650 test_bb->index, then_bb->index);
3652 /* THEN is small. */
3653 if (! cheap_bb_rtx_cost_p (then_bb,
3654 COSTS_N_INSNS (BRANCH_COST (optimize_bb_for_speed_p (then_edge->src),
3655 predictable_edge_p (then_edge)))))
3658 /* Registers set are dead, or are predicable. */
3659 if (! dead_or_predicable (test_bb, then_bb, else_bb,
3660 single_succ (then_bb), 1))
3663 /* Conversion went ok, including moving the insns and fixing up the
3664 jump. Adjust the CFG to match. */
3666 /* We can avoid creating a new basic block if then_bb is immediately
3667 followed by else_bb, i.e. deleting then_bb allows test_bb to fall
3670 if (then_bb->next_bb == else_bb
3671 && then_bb->prev_bb == test_bb
3672 && else_bb != EXIT_BLOCK_PTR)
3674 redirect_edge_succ (FALLTHRU_EDGE (test_bb), else_bb);
3678 new_bb = redirect_edge_and_branch_force (FALLTHRU_EDGE (test_bb),
3681 df_set_bb_dirty (test_bb);
3682 df_set_bb_dirty (else_bb);
3684 then_bb_index = then_bb->index;
3685 delete_basic_block (then_bb);
3687 /* Make rest of code believe that the newly created block is the THEN_BB
3688 block we removed. */
3691 df_bb_replace (then_bb_index, new_bb);
3692 /* Since the fallthru edge was redirected from test_bb to new_bb,
3693 we need to ensure that new_bb is in the same partition as
3694 test bb (you can not fall through across section boundaries). */
3695 BB_COPY_PARTITION (new_bb, test_bb);
3699 num_updated_if_blocks++;
3704 /* Test for case 2 above. */
3707 find_if_case_2 (basic_block test_bb, edge then_edge, edge else_edge)
3709 basic_block then_bb = then_edge->dest;
3710 basic_block else_bb = else_edge->dest;
3714 /* If we are partitioning hot/cold basic blocks, we don't want to
3715 mess up unconditional or indirect jumps that cross between hot
3718 Basic block partitioning may result in some jumps that appear to
3719 be optimizable (or blocks that appear to be mergeable), but which really
3720 must be left untouched (they are required to make it safely across
3721 partition boundaries). See the comments at the top of
3722 bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */
3724 if ((BB_END (then_bb)
3725 && find_reg_note (BB_END (then_bb), REG_CROSSING_JUMP, NULL_RTX))
3726 || (BB_END (test_bb)
3727 && find_reg_note (BB_END (test_bb), REG_CROSSING_JUMP, NULL_RTX))
3728 || (BB_END (else_bb)
3729 && find_reg_note (BB_END (else_bb), REG_CROSSING_JUMP,
3733 /* ELSE has one successor. */
3734 if (!single_succ_p (else_bb))
3737 else_succ = single_succ_edge (else_bb);
3739 /* ELSE outgoing edge is not complex. */
3740 if (else_succ->flags & EDGE_COMPLEX)
3743 /* ELSE has one predecessor. */
3744 if (!single_pred_p (else_bb))
3747 /* THEN is not EXIT. */
3748 if (then_bb->index < NUM_FIXED_BLOCKS)
3751 /* ELSE is predicted or SUCC(ELSE) postdominates THEN. */
3752 note = find_reg_note (BB_END (test_bb), REG_BR_PROB, NULL_RTX);
3753 if (note && INTVAL (XEXP (note, 0)) >= REG_BR_PROB_BASE / 2)
3755 else if (else_succ->dest->index < NUM_FIXED_BLOCKS
3756 || dominated_by_p (CDI_POST_DOMINATORS, then_bb,
3762 num_possible_if_blocks++;
3765 "\nIF-CASE-2 found, start %d, else %d\n",
3766 test_bb->index, else_bb->index);
3768 /* ELSE is small. */
3769 if (! cheap_bb_rtx_cost_p (else_bb,
3770 COSTS_N_INSNS (BRANCH_COST (optimize_bb_for_speed_p (else_edge->src),
3771 predictable_edge_p (else_edge)))))
3774 /* Registers set are dead, or are predicable. */
3775 if (! dead_or_predicable (test_bb, else_bb, then_bb, else_succ->dest, 0))
3778 /* Conversion went ok, including moving the insns and fixing up the
3779 jump. Adjust the CFG to match. */
3781 df_set_bb_dirty (test_bb);
3782 df_set_bb_dirty (then_bb);
3783 delete_basic_block (else_bb);
3786 num_updated_if_blocks++;
3788 /* ??? We may now fallthru from one of THEN's successors into a join
3789 block. Rerun cleanup_cfg? Examine things manually? Wait? */
3794 /* A subroutine of dead_or_predicable called through for_each_rtx.
3795 Return 1 if a memory is found. */
3798 find_memory (rtx *px, void *data ATTRIBUTE_UNUSED)
3803 /* Used by the code above to perform the actual rtl transformations.
3804 Return TRUE if successful.
3806 TEST_BB is the block containing the conditional branch. MERGE_BB
3807 is the block containing the code to manipulate. NEW_DEST is the
3808 label TEST_BB should be branching to after the conversion.
3809 REVERSEP is true if the sense of the branch should be reversed. */
3812 dead_or_predicable (basic_block test_bb, basic_block merge_bb,
3813 basic_block other_bb, basic_block new_dest, int reversep)
3815 rtx head, end, jump, earliest = NULL_RTX, old_dest, new_label = NULL_RTX;
3816 /* Number of pending changes. */
3817 int n_validated_changes = 0;
3819 jump = BB_END (test_bb);
3821 /* Find the extent of the real code in the merge block. */
3822 head = BB_HEAD (merge_bb);
3823 end = BB_END (merge_bb);
3825 while (DEBUG_INSN_P (end) && end != head)
3826 end = PREV_INSN (end);
3828 /* If merge_bb ends with a tablejump, predicating/moving insn's
3829 into test_bb and then deleting merge_bb will result in the jumptable
3830 that follows merge_bb being removed along with merge_bb and then we
3831 get an unresolved reference to the jumptable. */
3832 if (tablejump_p (end, NULL, NULL))
3836 head = NEXT_INSN (head);
3837 while (DEBUG_INSN_P (head) && head != end)
3838 head = NEXT_INSN (head);
3843 head = end = NULL_RTX;
3846 head = NEXT_INSN (head);
3847 while (DEBUG_INSN_P (head) && head != end)
3848 head = NEXT_INSN (head);
3855 head = end = NULL_RTX;
3858 end = PREV_INSN (end);
3859 while (DEBUG_INSN_P (end) && end != head)
3860 end = PREV_INSN (end);
3863 /* Disable handling dead code by conditional execution if the machine needs
3864 to do anything funny with the tests, etc. */
3865 #ifndef IFCVT_MODIFY_TESTS
3866 if (targetm.have_conditional_execution ())
3868 /* In the conditional execution case, we have things easy. We know
3869 the condition is reversible. We don't have to check life info
3870 because we're going to conditionally execute the code anyway.
3871 All that's left is making sure the insns involved can actually
3876 cond = cond_exec_get_condition (jump);
3880 prob_val = find_reg_note (jump, REG_BR_PROB, NULL_RTX);
3882 prob_val = XEXP (prob_val, 0);
3886 enum rtx_code rev = reversed_comparison_code (cond, jump);
3889 cond = gen_rtx_fmt_ee (rev, GET_MODE (cond), XEXP (cond, 0),
3892 prob_val = GEN_INT (REG_BR_PROB_BASE - INTVAL (prob_val));
3895 if (cond_exec_process_insns (NULL, head, end, cond, prob_val, 0)
3896 && verify_changes (0))
3897 n_validated_changes = num_validated_changes ();
3904 /* Try the NCE path if the CE path did not result in any changes. */
3905 if (n_validated_changes == 0)
3907 /* In the non-conditional execution case, we have to verify that there
3908 are no trapping operations, no calls, no references to memory, and
3909 that any registers modified are dead at the branch site. */
3911 rtx insn, cond, prev;
3912 bitmap merge_set, test_live, test_set;
3913 unsigned i, fail = 0;
3916 /* Check for no calls or trapping operations. */
3917 for (insn = head; ; insn = NEXT_INSN (insn))
3921 if (NONDEBUG_INSN_P (insn))
3923 if (may_trap_p (PATTERN (insn)))
3926 /* ??? Even non-trapping memories such as stack frame
3927 references must be avoided. For stores, we collect
3928 no lifetime info; for reads, we'd have to assert
3929 true_dependence false against every store in the
3931 if (for_each_rtx (&PATTERN (insn), find_memory, NULL))
3938 if (! any_condjump_p (jump))
3941 /* Find the extent of the conditional. */
3942 cond = noce_get_condition (jump, &earliest, false);
3947 MERGE_SET = set of registers set in MERGE_BB
3948 TEST_LIVE = set of registers live at EARLIEST
3949 TEST_SET = set of registers set between EARLIEST and the
3950 end of the block. */
3952 merge_set = BITMAP_ALLOC (®_obstack);
3953 test_live = BITMAP_ALLOC (®_obstack);
3954 test_set = BITMAP_ALLOC (®_obstack);
3956 /* ??? bb->local_set is only valid during calculate_global_regs_live,
3957 so we must recompute usage for MERGE_BB. Not so bad, I suppose,
3958 since we've already asserted that MERGE_BB is small. */
3959 /* If we allocated new pseudos (e.g. in the conditional move
3960 expander called from noce_emit_cmove), we must resize the
3962 if (max_regno < max_reg_num ())
3963 max_regno = max_reg_num ();
3965 FOR_BB_INSNS (merge_bb, insn)
3967 if (NONDEBUG_INSN_P (insn))
3969 unsigned int uid = INSN_UID (insn);
3971 for (def_rec = DF_INSN_UID_DEFS (uid); *def_rec; def_rec++)
3973 df_ref def = *def_rec;
3974 bitmap_set_bit (merge_set, DF_REF_REGNO (def));
3979 /* For small register class machines, don't lengthen lifetimes of
3980 hard registers before reload. */
3981 if (SMALL_REGISTER_CLASSES && ! reload_completed)
3983 EXECUTE_IF_SET_IN_BITMAP (merge_set, 0, i, bi)
3985 if (i < FIRST_PSEUDO_REGISTER
3987 && ! global_regs[i])
3992 /* For TEST, we're interested in a range of insns, not a whole block.
3993 Moreover, we're interested in the insns live from OTHER_BB. */
3995 /* The loop below takes the set of live registers
3996 after JUMP, and calculates the live set before EARLIEST. */
3997 bitmap_copy (test_live, df_get_live_in (other_bb));
3998 df_simulate_initialize_backwards (test_bb, test_live);
3999 for (insn = jump; ; insn = prev)
4003 df_simulate_find_defs (insn, test_set);
4004 df_simulate_one_insn_backwards (test_bb, insn, test_live);
4006 prev = PREV_INSN (insn);
4007 if (insn == earliest)
4011 /* We can perform the transformation if
4012 MERGE_SET & (TEST_SET | TEST_LIVE)
4014 TEST_SET & DF_LIVE_IN (merge_bb)
4017 if (bitmap_intersect_p (test_set, merge_set)
4018 || bitmap_intersect_p (test_live, merge_set)
4019 || bitmap_intersect_p (test_set, df_get_live_in (merge_bb)))
4022 BITMAP_FREE (merge_set);
4023 BITMAP_FREE (test_live);
4024 BITMAP_FREE (test_set);
4031 /* We don't want to use normal invert_jump or redirect_jump because
4032 we don't want to delete_insn called. Also, we want to do our own
4033 change group management. */
4035 old_dest = JUMP_LABEL (jump);
4036 if (other_bb != new_dest)
4038 new_label = block_label (new_dest);
4040 ? ! invert_jump_1 (jump, new_label)
4041 : ! redirect_jump_1 (jump, new_label))
4045 if (verify_changes (n_validated_changes))
4046 confirm_change_group ();
4050 if (other_bb != new_dest)
4052 redirect_jump_2 (jump, old_dest, new_label, 0, reversep);
4054 redirect_edge_succ (BRANCH_EDGE (test_bb), new_dest);
4057 gcov_type count, probability;
4058 count = BRANCH_EDGE (test_bb)->count;
4059 BRANCH_EDGE (test_bb)->count = FALLTHRU_EDGE (test_bb)->count;
4060 FALLTHRU_EDGE (test_bb)->count = count;
4061 probability = BRANCH_EDGE (test_bb)->probability;
4062 BRANCH_EDGE (test_bb)->probability
4063 = FALLTHRU_EDGE (test_bb)->probability;
4064 FALLTHRU_EDGE (test_bb)->probability = probability;
4065 update_br_prob_note (test_bb);
4069 /* Move the insns out of MERGE_BB to before the branch. */
4074 if (end == BB_END (merge_bb))
4075 BB_END (merge_bb) = PREV_INSN (head);
4077 /* PR 21767: When moving insns above a conditional branch, REG_EQUAL
4078 notes might become invalid. */
4084 if (! INSN_P (insn))
4086 note = find_reg_note (insn, REG_EQUAL, NULL_RTX);
4089 set = single_set (insn);
4090 if (!set || !function_invariant_p (SET_SRC (set)))
4091 remove_note (insn, note);
4092 } while (insn != end && (insn = NEXT_INSN (insn)));
4094 reorder_insns (head, end, PREV_INSN (earliest));
4097 /* Remove the jump and edge if we can. */
4098 if (other_bb == new_dest)
4101 remove_edge (BRANCH_EDGE (test_bb));
4102 /* ??? Can't merge blocks here, as then_bb is still in use.
4103 At minimum, the merge will get done just before bb-reorder. */
4113 /* Main entry point for all if-conversion. */
4123 df_live_add_problem ();
4124 df_live_set_all_dirty ();
4127 num_possible_if_blocks = 0;
4128 num_updated_if_blocks = 0;
4129 num_true_changes = 0;
4131 loop_optimizer_init (AVOID_CFG_MODIFICATIONS);
4132 mark_loop_exit_edges ();
4133 loop_optimizer_finalize ();
4134 free_dominance_info (CDI_DOMINATORS);
4136 /* Compute postdominators. */
4137 calculate_dominance_info (CDI_POST_DOMINATORS);
4139 df_set_flags (DF_LR_RUN_DCE);
4141 /* Go through each of the basic blocks looking for things to convert. If we
4142 have conditional execution, we make multiple passes to allow us to handle
4143 IF-THEN{-ELSE} blocks within other IF-THEN{-ELSE} blocks. */
4148 /* Only need to do dce on the first pass. */
4149 df_clear_flags (DF_LR_RUN_DCE);
4150 cond_exec_changed_p = FALSE;
4153 #ifdef IFCVT_MULTIPLE_DUMPS
4154 if (dump_file && pass > 1)
4155 fprintf (dump_file, "\n\n========== Pass %d ==========\n", pass);
4161 while (!df_get_bb_dirty (bb)
4162 && (new_bb = find_if_header (bb, pass)) != NULL)
4166 #ifdef IFCVT_MULTIPLE_DUMPS
4167 if (dump_file && cond_exec_changed_p)
4169 if (dump_flags & TDF_SLIM)
4170 print_rtl_slim_with_bb (dump_file, get_insns (), dump_flags);
4172 print_rtl_with_bb (dump_file, get_insns ());
4176 while (cond_exec_changed_p);
4178 #ifdef IFCVT_MULTIPLE_DUMPS
4180 fprintf (dump_file, "\n\n========== no more changes\n");
4183 free_dominance_info (CDI_POST_DOMINATORS);
4188 clear_aux_for_blocks ();
4190 /* If we allocated new pseudos, we must resize the array for sched1. */
4191 if (max_regno < max_reg_num ())
4192 max_regno = max_reg_num ();
4194 /* Write the final stats. */
4195 if (dump_file && num_possible_if_blocks > 0)
4198 "\n%d possible IF blocks searched.\n",
4199 num_possible_if_blocks);
4201 "%d IF blocks converted.\n",
4202 num_updated_if_blocks);
4204 "%d true changes made.\n\n\n",
4209 df_remove_problem (df_live);
4211 #ifdef ENABLE_CHECKING
4212 verify_flow_info ();
4217 gate_handle_if_conversion (void)
4219 return (optimize > 0)
4220 && dbg_cnt (if_conversion);
4223 /* If-conversion and CFG cleanup. */
4225 rest_of_handle_if_conversion (void)
4227 if (flag_if_conversion)
4230 dump_flow_info (dump_file, dump_flags);
4231 cleanup_cfg (CLEANUP_EXPENSIVE);
4239 struct rtl_opt_pass pass_rtl_ifcvt =
4244 gate_handle_if_conversion, /* gate */
4245 rest_of_handle_if_conversion, /* execute */
4248 0, /* static_pass_number */
4249 TV_IFCVT, /* tv_id */
4250 0, /* properties_required */
4251 0, /* properties_provided */
4252 0, /* properties_destroyed */
4253 0, /* todo_flags_start */
4254 TODO_df_finish | TODO_verify_rtl_sharing |
4255 TODO_dump_func /* todo_flags_finish */
4260 gate_handle_if_after_combine (void)
4262 return optimize > 0 && flag_if_conversion
4263 && dbg_cnt (if_after_combine);
4267 /* Rerun if-conversion, as combine may have simplified things enough
4268 to now meet sequence length restrictions. */
4270 rest_of_handle_if_after_combine (void)
4276 struct rtl_opt_pass pass_if_after_combine =
4281 gate_handle_if_after_combine, /* gate */
4282 rest_of_handle_if_after_combine, /* execute */
4285 0, /* static_pass_number */
4286 TV_IFCVT, /* tv_id */
4287 0, /* properties_required */
4288 0, /* properties_provided */
4289 0, /* properties_destroyed */
4290 0, /* todo_flags_start */
4291 TODO_df_finish | TODO_verify_rtl_sharing |
4293 TODO_ggc_collect /* todo_flags_finish */
4299 gate_handle_if_after_reload (void)
4301 return optimize > 0 && flag_if_conversion2
4302 && dbg_cnt (if_after_reload);
4306 rest_of_handle_if_after_reload (void)
4313 struct rtl_opt_pass pass_if_after_reload =
4318 gate_handle_if_after_reload, /* gate */
4319 rest_of_handle_if_after_reload, /* execute */
4322 0, /* static_pass_number */
4323 TV_IFCVT2, /* tv_id */
4324 0, /* properties_required */
4325 0, /* properties_provided */
4326 0, /* properties_destroyed */
4327 0, /* todo_flags_start */
4328 TODO_df_finish | TODO_verify_rtl_sharing |
4330 TODO_ggc_collect /* todo_flags_finish */