1 /* If-conversion support.
2 Copyright (C) 2000-2014 Free Software Foundation, Inc.
4 This file is part of GCC.
6 GCC is free software; you can redistribute it and/or modify it
7 under the terms of the GNU General Public License as published by
8 the Free Software Foundation; either version 3, or (at your option)
11 GCC is distributed in the hope that it will be useful, but WITHOUT
12 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
13 or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public
14 License for more details.
16 You should have received a copy of the GNU General Public License
17 along with GCC; see the file COPYING3. If not see
18 <http://www.gnu.org/licenses/>. */
22 #include "coretypes.h"
29 #include "insn-config.h"
32 #include "hard-reg-set.h"
33 #include "basic-block.h"
37 #include "diagnostic-core.h"
41 #include "tree-pass.h"
46 #ifndef HAVE_conditional_move
47 #define HAVE_conditional_move 0
59 #ifndef MAX_CONDITIONAL_EXECUTE
60 #define MAX_CONDITIONAL_EXECUTE \
61 (BRANCH_COST (optimize_function_for_speed_p (cfun), false) \
65 #define IFCVT_MULTIPLE_DUMPS 1
67 #define NULL_BLOCK ((basic_block) NULL)
69 /* True if after combine pass. */
70 static bool ifcvt_after_combine
;
72 /* # of IF-THEN or IF-THEN-ELSE blocks we looked at */
73 static int num_possible_if_blocks
;
75 /* # of IF-THEN or IF-THEN-ELSE blocks were converted to conditional
77 static int num_updated_if_blocks
;
79 /* # of changes made. */
80 static int num_true_changes
;
82 /* Whether conditional execution changes were made. */
83 static int cond_exec_changed_p
;
85 /* Forward references. */
86 static int count_bb_insns (const_basic_block
);
87 static bool cheap_bb_rtx_cost_p (const_basic_block
, int, int);
88 static rtx_insn
*first_active_insn (basic_block
);
89 static rtx_insn
*last_active_insn (basic_block
, int);
90 static rtx_insn
*find_active_insn_before (basic_block
, rtx_insn
*);
91 static rtx_insn
*find_active_insn_after (basic_block
, rtx_insn
*);
92 static basic_block
block_fallthru (basic_block
);
93 static int cond_exec_process_insns (ce_if_block
*, rtx_insn
*, rtx
, rtx
, int,
95 static rtx
cond_exec_get_condition (rtx
);
96 static rtx
noce_get_condition (rtx_insn
*, rtx_insn
**, bool);
97 static int noce_operand_ok (const_rtx
);
98 static void merge_if_block (ce_if_block
*);
99 static int find_cond_trap (basic_block
, edge
, edge
);
100 static basic_block
find_if_header (basic_block
, int);
101 static int block_jumps_and_fallthru_p (basic_block
, basic_block
);
102 static int noce_find_if_block (basic_block
, edge
, edge
, int);
103 static int cond_exec_find_if_block (ce_if_block
*);
104 static int find_if_case_1 (basic_block
, edge
, edge
);
105 static int find_if_case_2 (basic_block
, edge
, edge
);
106 static int dead_or_predicable (basic_block
, basic_block
, basic_block
,
108 static void noce_emit_move_insn (rtx
, rtx
);
109 static rtx_insn
*block_has_only_trap (basic_block
);
111 /* Count the number of non-jump active insns in BB. */
114 count_bb_insns (const_basic_block bb
)
117 rtx_insn
*insn
= BB_HEAD (bb
);
121 if (active_insn_p (insn
) && !JUMP_P (insn
))
124 if (insn
== BB_END (bb
))
126 insn
= NEXT_INSN (insn
);
132 /* Determine whether the total insn_rtx_cost on non-jump insns in
133 basic block BB is less than MAX_COST. This function returns
134 false if the cost of any instruction could not be estimated.
136 The cost of the non-jump insns in BB is scaled by REG_BR_PROB_BASE
137 as those insns are being speculated. MAX_COST is scaled with SCALE
138 plus a small fudge factor. */
141 cheap_bb_rtx_cost_p (const_basic_block bb
, int scale
, int max_cost
)
144 rtx_insn
*insn
= BB_HEAD (bb
);
145 bool speed
= optimize_bb_for_speed_p (bb
);
147 /* Set scale to REG_BR_PROB_BASE to void the identical scaling
148 applied to insn_rtx_cost when optimizing for size. Only do
149 this after combine because if-conversion might interfere with
150 passes before combine.
152 Use optimize_function_for_speed_p instead of the pre-defined
153 variable speed to make sure it is set to same value for all
154 basic blocks in one if-conversion transformation. */
155 if (!optimize_function_for_speed_p (cfun
) && ifcvt_after_combine
)
156 scale
= REG_BR_PROB_BASE
;
157 /* Our branch probability/scaling factors are just estimates and don't
158 account for cases where we can get speculation for free and other
159 secondary benefits. So we fudge the scale factor to make speculating
160 appear a little more profitable when optimizing for performance. */
162 scale
+= REG_BR_PROB_BASE
/ 8;
169 if (NONJUMP_INSN_P (insn
))
171 int cost
= insn_rtx_cost (PATTERN (insn
), speed
) * REG_BR_PROB_BASE
;
175 /* If this instruction is the load or set of a "stack" register,
176 such as a floating point register on x87, then the cost of
177 speculatively executing this insn may need to include
178 the additional cost of popping its result off of the
179 register stack. Unfortunately, correctly recognizing and
180 accounting for this additional overhead is tricky, so for
181 now we simply prohibit such speculative execution. */
184 rtx set
= single_set (insn
);
185 if (set
&& STACK_REG_P (SET_DEST (set
)))
191 if (count
>= max_cost
)
194 else if (CALL_P (insn
))
197 if (insn
== BB_END (bb
))
199 insn
= NEXT_INSN (insn
);
205 /* Return the first non-jump active insn in the basic block. */
208 first_active_insn (basic_block bb
)
210 rtx_insn
*insn
= BB_HEAD (bb
);
214 if (insn
== BB_END (bb
))
216 insn
= NEXT_INSN (insn
);
219 while (NOTE_P (insn
) || DEBUG_INSN_P (insn
))
221 if (insn
== BB_END (bb
))
223 insn
= NEXT_INSN (insn
);
232 /* Return the last non-jump active (non-jump) insn in the basic block. */
235 last_active_insn (basic_block bb
, int skip_use_p
)
237 rtx_insn
*insn
= BB_END (bb
);
238 rtx_insn
*head
= BB_HEAD (bb
);
242 || DEBUG_INSN_P (insn
)
244 && NONJUMP_INSN_P (insn
)
245 && GET_CODE (PATTERN (insn
)) == USE
))
249 insn
= PREV_INSN (insn
);
258 /* Return the active insn before INSN inside basic block CURR_BB. */
261 find_active_insn_before (basic_block curr_bb
, rtx_insn
*insn
)
263 if (!insn
|| insn
== BB_HEAD (curr_bb
))
266 while ((insn
= PREV_INSN (insn
)) != NULL_RTX
)
268 if (NONJUMP_INSN_P (insn
) || JUMP_P (insn
) || CALL_P (insn
))
271 /* No other active insn all the way to the start of the basic block. */
272 if (insn
== BB_HEAD (curr_bb
))
279 /* Return the active insn after INSN inside basic block CURR_BB. */
282 find_active_insn_after (basic_block curr_bb
, rtx_insn
*insn
)
284 if (!insn
|| insn
== BB_END (curr_bb
))
287 while ((insn
= NEXT_INSN (insn
)) != NULL_RTX
)
289 if (NONJUMP_INSN_P (insn
) || JUMP_P (insn
) || CALL_P (insn
))
292 /* No other active insn all the way to the end of the basic block. */
293 if (insn
== BB_END (curr_bb
))
300 /* Return the basic block reached by falling though the basic block BB. */
303 block_fallthru (basic_block bb
)
305 edge e
= find_fallthru_edge (bb
->succs
);
307 return (e
) ? e
->dest
: NULL_BLOCK
;
310 /* Return true if RTXs A and B can be safely interchanged. */
313 rtx_interchangeable_p (const_rtx a
, const_rtx b
)
315 if (!rtx_equal_p (a
, b
))
318 if (GET_CODE (a
) != MEM
)
321 /* A dead type-unsafe memory reference is legal, but a live type-unsafe memory
322 reference is not. Interchanging a dead type-unsafe memory reference with
323 a live type-safe one creates a live type-unsafe memory reference, in other
324 words, it makes the program illegal.
325 We check here conservatively whether the two memory references have equal
326 memory attributes. */
328 return mem_attrs_eq_p (get_mem_attrs (a
), get_mem_attrs (b
));
332 /* Go through a bunch of insns, converting them to conditional
333 execution format if possible. Return TRUE if all of the non-note
334 insns were processed. */
337 cond_exec_process_insns (ce_if_block
*ce_info ATTRIBUTE_UNUSED
,
338 /* if block information */rtx_insn
*start
,
339 /* first insn to look at */rtx end
,
340 /* last insn to look at */rtx test
,
341 /* conditional execution test */int prob_val
,
342 /* probability of branch taken. */int mod_ok
)
344 int must_be_last
= FALSE
;
352 for (insn
= start
; ; insn
= NEXT_INSN (insn
))
354 /* dwarf2out can't cope with conditional prologues. */
355 if (NOTE_P (insn
) && NOTE_KIND (insn
) == NOTE_INSN_PROLOGUE_END
)
358 if (NOTE_P (insn
) || DEBUG_INSN_P (insn
))
361 gcc_assert (NONJUMP_INSN_P (insn
) || CALL_P (insn
));
363 /* dwarf2out can't cope with conditional unwind info. */
364 if (RTX_FRAME_RELATED_P (insn
))
367 /* Remove USE insns that get in the way. */
368 if (reload_completed
&& GET_CODE (PATTERN (insn
)) == USE
)
370 /* ??? Ug. Actually unlinking the thing is problematic,
371 given what we'd have to coordinate with our callers. */
372 SET_INSN_DELETED (insn
);
376 /* Last insn wasn't last? */
380 if (modified_in_p (test
, insn
))
387 /* Now build the conditional form of the instruction. */
388 pattern
= PATTERN (insn
);
389 xtest
= copy_rtx (test
);
391 /* If this is already a COND_EXEC, rewrite the test to be an AND of the
393 if (GET_CODE (pattern
) == COND_EXEC
)
395 if (GET_MODE (xtest
) != GET_MODE (COND_EXEC_TEST (pattern
)))
398 xtest
= gen_rtx_AND (GET_MODE (xtest
), xtest
,
399 COND_EXEC_TEST (pattern
));
400 pattern
= COND_EXEC_CODE (pattern
);
403 pattern
= gen_rtx_COND_EXEC (VOIDmode
, xtest
, pattern
);
405 /* If the machine needs to modify the insn being conditionally executed,
406 say for example to force a constant integer operand into a temp
407 register, do so here. */
408 #ifdef IFCVT_MODIFY_INSN
409 IFCVT_MODIFY_INSN (ce_info
, pattern
, insn
);
414 validate_change (insn
, &PATTERN (insn
), pattern
, 1);
416 if (CALL_P (insn
) && prob_val
>= 0)
417 validate_change (insn
, ®_NOTES (insn
),
418 gen_rtx_INT_LIST ((enum machine_mode
) REG_BR_PROB
,
419 prob_val
, REG_NOTES (insn
)), 1);
429 /* Return the condition for a jump. Do not do any special processing. */
432 cond_exec_get_condition (rtx jump
)
436 if (any_condjump_p (jump
))
437 test_if
= SET_SRC (pc_set (jump
));
440 cond
= XEXP (test_if
, 0);
442 /* If this branches to JUMP_LABEL when the condition is false,
443 reverse the condition. */
444 if (GET_CODE (XEXP (test_if
, 2)) == LABEL_REF
445 && XEXP (XEXP (test_if
, 2), 0) == JUMP_LABEL (jump
))
447 enum rtx_code rev
= reversed_comparison_code (cond
, jump
);
451 cond
= gen_rtx_fmt_ee (rev
, GET_MODE (cond
), XEXP (cond
, 0),
458 /* Given a simple IF-THEN or IF-THEN-ELSE block, attempt to convert it
459 to conditional execution. Return TRUE if we were successful at
460 converting the block. */
463 cond_exec_process_if_block (ce_if_block
* ce_info
,
464 /* if block information */int do_multiple_p
)
466 basic_block test_bb
= ce_info
->test_bb
; /* last test block */
467 basic_block then_bb
= ce_info
->then_bb
; /* THEN */
468 basic_block else_bb
= ce_info
->else_bb
; /* ELSE or NULL */
469 rtx test_expr
; /* expression in IF_THEN_ELSE that is tested */
470 rtx_insn
*then_start
; /* first insn in THEN block */
471 rtx_insn
*then_end
; /* last insn + 1 in THEN block */
472 rtx_insn
*else_start
= NULL
; /* first insn in ELSE block or NULL */
473 rtx_insn
*else_end
= NULL
; /* last insn + 1 in ELSE block */
474 int max
; /* max # of insns to convert. */
475 int then_mod_ok
; /* whether conditional mods are ok in THEN */
476 rtx true_expr
; /* test for else block insns */
477 rtx false_expr
; /* test for then block insns */
478 int true_prob_val
; /* probability of else block */
479 int false_prob_val
; /* probability of then block */
480 rtx_insn
*then_last_head
= NULL
; /* Last match at the head of THEN */
481 rtx_insn
*else_last_head
= NULL
; /* Last match at the head of ELSE */
482 rtx_insn
*then_first_tail
= NULL
; /* First match at the tail of THEN */
483 rtx_insn
*else_first_tail
= NULL
; /* First match at the tail of ELSE */
484 int then_n_insns
, else_n_insns
, n_insns
;
485 enum rtx_code false_code
;
488 /* If test is comprised of && or || elements, and we've failed at handling
489 all of them together, just use the last test if it is the special case of
490 && elements without an ELSE block. */
491 if (!do_multiple_p
&& ce_info
->num_multiple_test_blocks
)
493 if (else_bb
|| ! ce_info
->and_and_p
)
496 ce_info
->test_bb
= test_bb
= ce_info
->last_test_bb
;
497 ce_info
->num_multiple_test_blocks
= 0;
498 ce_info
->num_and_and_blocks
= 0;
499 ce_info
->num_or_or_blocks
= 0;
502 /* Find the conditional jump to the ELSE or JOIN part, and isolate
504 test_expr
= cond_exec_get_condition (BB_END (test_bb
));
508 /* If the conditional jump is more than just a conditional jump,
509 then we can not do conditional execution conversion on this block. */
510 if (! onlyjump_p (BB_END (test_bb
)))
513 /* Collect the bounds of where we're to search, skipping any labels, jumps
514 and notes at the beginning and end of the block. Then count the total
515 number of insns and see if it is small enough to convert. */
516 then_start
= first_active_insn (then_bb
);
517 then_end
= last_active_insn (then_bb
, TRUE
);
518 then_n_insns
= ce_info
->num_then_insns
= count_bb_insns (then_bb
);
519 n_insns
= then_n_insns
;
520 max
= MAX_CONDITIONAL_EXECUTE
;
527 else_start
= first_active_insn (else_bb
);
528 else_end
= last_active_insn (else_bb
, TRUE
);
529 else_n_insns
= ce_info
->num_else_insns
= count_bb_insns (else_bb
);
530 n_insns
+= else_n_insns
;
532 /* Look for matching sequences at the head and tail of the two blocks,
533 and limit the range of insns to be converted if possible. */
534 n_matching
= flow_find_cross_jump (then_bb
, else_bb
,
535 &then_first_tail
, &else_first_tail
,
537 if (then_first_tail
== BB_HEAD (then_bb
))
538 then_start
= then_end
= NULL
;
539 if (else_first_tail
== BB_HEAD (else_bb
))
540 else_start
= else_end
= NULL
;
545 then_end
= find_active_insn_before (then_bb
, then_first_tail
);
547 else_end
= find_active_insn_before (else_bb
, else_first_tail
);
548 n_insns
-= 2 * n_matching
;
553 && then_n_insns
> n_matching
554 && else_n_insns
> n_matching
)
556 int longest_match
= MIN (then_n_insns
- n_matching
,
557 else_n_insns
- n_matching
);
559 = flow_find_head_matching_sequence (then_bb
, else_bb
,
568 /* We won't pass the insns in the head sequence to
569 cond_exec_process_insns, so we need to test them here
570 to make sure that they don't clobber the condition. */
571 for (insn
= BB_HEAD (then_bb
);
572 insn
!= NEXT_INSN (then_last_head
);
573 insn
= NEXT_INSN (insn
))
574 if (!LABEL_P (insn
) && !NOTE_P (insn
)
575 && !DEBUG_INSN_P (insn
)
576 && modified_in_p (test_expr
, insn
))
580 if (then_last_head
== then_end
)
581 then_start
= then_end
= NULL
;
582 if (else_last_head
== else_end
)
583 else_start
= else_end
= NULL
;
588 then_start
= find_active_insn_after (then_bb
, then_last_head
);
590 else_start
= find_active_insn_after (else_bb
, else_last_head
);
591 n_insns
-= 2 * n_matching
;
599 /* Map test_expr/test_jump into the appropriate MD tests to use on
600 the conditionally executed code. */
602 true_expr
= test_expr
;
604 false_code
= reversed_comparison_code (true_expr
, BB_END (test_bb
));
605 if (false_code
!= UNKNOWN
)
606 false_expr
= gen_rtx_fmt_ee (false_code
, GET_MODE (true_expr
),
607 XEXP (true_expr
, 0), XEXP (true_expr
, 1));
609 false_expr
= NULL_RTX
;
611 #ifdef IFCVT_MODIFY_TESTS
612 /* If the machine description needs to modify the tests, such as setting a
613 conditional execution register from a comparison, it can do so here. */
614 IFCVT_MODIFY_TESTS (ce_info
, true_expr
, false_expr
);
616 /* See if the conversion failed. */
617 if (!true_expr
|| !false_expr
)
621 note
= find_reg_note (BB_END (test_bb
), REG_BR_PROB
, NULL_RTX
);
624 true_prob_val
= XINT (note
, 0);
625 false_prob_val
= REG_BR_PROB_BASE
- true_prob_val
;
633 /* If we have && or || tests, do them here. These tests are in the adjacent
634 blocks after the first block containing the test. */
635 if (ce_info
->num_multiple_test_blocks
> 0)
637 basic_block bb
= test_bb
;
638 basic_block last_test_bb
= ce_info
->last_test_bb
;
645 rtx_insn
*start
, *end
;
647 enum rtx_code f_code
;
649 bb
= block_fallthru (bb
);
650 start
= first_active_insn (bb
);
651 end
= last_active_insn (bb
, TRUE
);
653 && ! cond_exec_process_insns (ce_info
, start
, end
, false_expr
,
654 false_prob_val
, FALSE
))
657 /* If the conditional jump is more than just a conditional jump, then
658 we can not do conditional execution conversion on this block. */
659 if (! onlyjump_p (BB_END (bb
)))
662 /* Find the conditional jump and isolate the test. */
663 t
= cond_exec_get_condition (BB_END (bb
));
667 f_code
= reversed_comparison_code (t
, BB_END (bb
));
668 if (f_code
== UNKNOWN
)
671 f
= gen_rtx_fmt_ee (f_code
, GET_MODE (t
), XEXP (t
, 0), XEXP (t
, 1));
672 if (ce_info
->and_and_p
)
674 t
= gen_rtx_AND (GET_MODE (t
), true_expr
, t
);
675 f
= gen_rtx_IOR (GET_MODE (t
), false_expr
, f
);
679 t
= gen_rtx_IOR (GET_MODE (t
), true_expr
, t
);
680 f
= gen_rtx_AND (GET_MODE (t
), false_expr
, f
);
683 /* If the machine description needs to modify the tests, such as
684 setting a conditional execution register from a comparison, it can
686 #ifdef IFCVT_MODIFY_MULTIPLE_TESTS
687 IFCVT_MODIFY_MULTIPLE_TESTS (ce_info
, bb
, t
, f
);
689 /* See if the conversion failed. */
697 while (bb
!= last_test_bb
);
700 /* For IF-THEN-ELSE blocks, we don't allow modifications of the test
701 on then THEN block. */
702 then_mod_ok
= (else_bb
== NULL_BLOCK
);
704 /* Go through the THEN and ELSE blocks converting the insns if possible
705 to conditional execution. */
709 || ! cond_exec_process_insns (ce_info
, then_start
, then_end
,
710 false_expr
, false_prob_val
,
714 if (else_bb
&& else_end
715 && ! cond_exec_process_insns (ce_info
, else_start
, else_end
,
716 true_expr
, true_prob_val
, TRUE
))
719 /* If we cannot apply the changes, fail. Do not go through the normal fail
720 processing, since apply_change_group will call cancel_changes. */
721 if (! apply_change_group ())
723 #ifdef IFCVT_MODIFY_CANCEL
724 /* Cancel any machine dependent changes. */
725 IFCVT_MODIFY_CANCEL (ce_info
);
730 #ifdef IFCVT_MODIFY_FINAL
731 /* Do any machine dependent final modifications. */
732 IFCVT_MODIFY_FINAL (ce_info
);
735 /* Conversion succeeded. */
737 fprintf (dump_file
, "%d insn%s converted to conditional execution.\n",
738 n_insns
, (n_insns
== 1) ? " was" : "s were");
740 /* Merge the blocks! If we had matching sequences, make sure to delete one
741 copy at the appropriate location first: delete the copy in the THEN branch
742 for a tail sequence so that the remaining one is executed last for both
743 branches, and delete the copy in the ELSE branch for a head sequence so
744 that the remaining one is executed first for both branches. */
747 rtx_insn
*from
= then_first_tail
;
749 from
= find_active_insn_after (then_bb
, from
);
750 delete_insn_chain (from
, BB_END (then_bb
), false);
753 delete_insn_chain (first_active_insn (else_bb
), else_last_head
, false);
755 merge_if_block (ce_info
);
756 cond_exec_changed_p
= TRUE
;
760 #ifdef IFCVT_MODIFY_CANCEL
761 /* Cancel any machine dependent changes. */
762 IFCVT_MODIFY_CANCEL (ce_info
);
769 /* Used by noce_process_if_block to communicate with its subroutines.
771 The subroutines know that A and B may be evaluated freely. They
772 know that X is a register. They should insert new instructions
773 before cond_earliest. */
777 /* The basic blocks that make up the IF-THEN-{ELSE-,}JOIN block. */
778 basic_block test_bb
, then_bb
, else_bb
, join_bb
;
780 /* The jump that ends TEST_BB. */
783 /* The jump condition. */
786 /* New insns should be inserted before this one. */
787 rtx_insn
*cond_earliest
;
789 /* Insns in the THEN and ELSE block. There is always just this
790 one insns in those blocks. The insns are single_set insns.
791 If there was no ELSE block, INSN_B is the last insn before
792 COND_EARLIEST, or NULL_RTX. In the former case, the insn
793 operands are still valid, as if INSN_B was moved down below
795 rtx_insn
*insn_a
, *insn_b
;
797 /* The SET_SRC of INSN_A and INSN_B. */
800 /* The SET_DEST of INSN_A. */
803 /* True if this if block is not canonical. In the canonical form of
804 if blocks, the THEN_BB is the block reached via the fallthru edge
805 from TEST_BB. For the noce transformations, we allow the symmetric
807 bool then_else_reversed
;
809 /* Estimated cost of the particular branch instruction. */
813 static rtx
noce_emit_store_flag (struct noce_if_info
*, rtx
, int, int);
814 static int noce_try_move (struct noce_if_info
*);
815 static int noce_try_store_flag (struct noce_if_info
*);
816 static int noce_try_addcc (struct noce_if_info
*);
817 static int noce_try_store_flag_constants (struct noce_if_info
*);
818 static int noce_try_store_flag_mask (struct noce_if_info
*);
819 static rtx
noce_emit_cmove (struct noce_if_info
*, rtx
, enum rtx_code
, rtx
,
821 static int noce_try_cmove (struct noce_if_info
*);
822 static int noce_try_cmove_arith (struct noce_if_info
*);
823 static rtx
noce_get_alt_condition (struct noce_if_info
*, rtx
, rtx_insn
**);
824 static int noce_try_minmax (struct noce_if_info
*);
825 static int noce_try_abs (struct noce_if_info
*);
826 static int noce_try_sign_mask (struct noce_if_info
*);
828 /* Helper function for noce_try_store_flag*. */
831 noce_emit_store_flag (struct noce_if_info
*if_info
, rtx x
, int reversep
,
834 rtx cond
= if_info
->cond
;
838 cond_complex
= (! general_operand (XEXP (cond
, 0), VOIDmode
)
839 || ! general_operand (XEXP (cond
, 1), VOIDmode
));
841 /* If earliest == jump, or when the condition is complex, try to
842 build the store_flag insn directly. */
846 rtx set
= pc_set (if_info
->jump
);
847 cond
= XEXP (SET_SRC (set
), 0);
848 if (GET_CODE (XEXP (SET_SRC (set
), 2)) == LABEL_REF
849 && XEXP (XEXP (SET_SRC (set
), 2), 0) == JUMP_LABEL (if_info
->jump
))
850 reversep
= !reversep
;
851 if (if_info
->then_else_reversed
)
852 reversep
= !reversep
;
856 code
= reversed_comparison_code (cond
, if_info
->jump
);
858 code
= GET_CODE (cond
);
860 if ((if_info
->cond_earliest
== if_info
->jump
|| cond_complex
)
861 && (normalize
== 0 || STORE_FLAG_VALUE
== normalize
))
865 tmp
= gen_rtx_fmt_ee (code
, GET_MODE (x
), XEXP (cond
, 0),
867 tmp
= gen_rtx_SET (VOIDmode
, x
, tmp
);
870 tmp
= emit_insn (tmp
);
872 if (recog_memoized (tmp
) >= 0)
878 if_info
->cond_earliest
= if_info
->jump
;
886 /* Don't even try if the comparison operands or the mode of X are weird. */
887 if (cond_complex
|| !SCALAR_INT_MODE_P (GET_MODE (x
)))
890 return emit_store_flag (x
, code
, XEXP (cond
, 0),
891 XEXP (cond
, 1), VOIDmode
,
892 (code
== LTU
|| code
== LEU
893 || code
== GEU
|| code
== GTU
), normalize
);
896 /* Emit instruction to move an rtx, possibly into STRICT_LOW_PART.
897 X is the destination/target and Y is the value to copy. */
900 noce_emit_move_insn (rtx x
, rtx y
)
902 enum machine_mode outmode
;
906 if (GET_CODE (x
) != STRICT_LOW_PART
)
908 rtx seq
, insn
, target
;
912 /* Check that the SET_SRC is reasonable before calling emit_move_insn,
913 otherwise construct a suitable SET pattern ourselves. */
914 insn
= (OBJECT_P (y
) || CONSTANT_P (y
) || GET_CODE (y
) == SUBREG
)
915 ? emit_move_insn (x
, y
)
916 : emit_insn (gen_rtx_SET (VOIDmode
, x
, y
));
920 if (recog_memoized (insn
) <= 0)
922 if (GET_CODE (x
) == ZERO_EXTRACT
)
924 rtx op
= XEXP (x
, 0);
925 unsigned HOST_WIDE_INT size
= INTVAL (XEXP (x
, 1));
926 unsigned HOST_WIDE_INT start
= INTVAL (XEXP (x
, 2));
928 /* store_bit_field expects START to be relative to
929 BYTES_BIG_ENDIAN and adjusts this value for machines with
930 BITS_BIG_ENDIAN != BYTES_BIG_ENDIAN. In order to be able to
931 invoke store_bit_field again it is necessary to have the START
932 value from the first call. */
933 if (BITS_BIG_ENDIAN
!= BYTES_BIG_ENDIAN
)
936 start
= BITS_PER_UNIT
- start
- size
;
939 gcc_assert (REG_P (op
));
940 start
= BITS_PER_WORD
- start
- size
;
944 gcc_assert (start
< (MEM_P (op
) ? BITS_PER_UNIT
: BITS_PER_WORD
));
945 store_bit_field (op
, size
, start
, 0, 0, GET_MODE (x
), y
);
949 switch (GET_RTX_CLASS (GET_CODE (y
)))
952 ot
= code_to_optab (GET_CODE (y
));
956 target
= expand_unop (GET_MODE (y
), ot
, XEXP (y
, 0), x
, 0);
957 if (target
!= NULL_RTX
)
960 emit_move_insn (x
, target
);
969 ot
= code_to_optab (GET_CODE (y
));
973 target
= expand_binop (GET_MODE (y
), ot
,
974 XEXP (y
, 0), XEXP (y
, 1),
976 if (target
!= NULL_RTX
)
979 emit_move_insn (x
, target
);
996 inner
= XEXP (outer
, 0);
997 outmode
= GET_MODE (outer
);
998 bitpos
= SUBREG_BYTE (outer
) * BITS_PER_UNIT
;
999 store_bit_field (inner
, GET_MODE_BITSIZE (outmode
), bitpos
,
1003 /* Return sequence of instructions generated by if conversion. This
1004 function calls end_sequence() to end the current stream, ensures
1005 that are instructions are unshared, recognizable non-jump insns.
1006 On failure, this function returns a NULL_RTX. */
1009 end_ifcvt_sequence (struct noce_if_info
*if_info
)
1012 rtx_insn
*seq
= get_insns ();
1014 set_used_flags (if_info
->x
);
1015 set_used_flags (if_info
->cond
);
1016 set_used_flags (if_info
->a
);
1017 set_used_flags (if_info
->b
);
1018 unshare_all_rtl_in_chain (seq
);
1021 /* Make sure that all of the instructions emitted are recognizable,
1022 and that we haven't introduced a new jump instruction.
1023 As an exercise for the reader, build a general mechanism that
1024 allows proper placement of required clobbers. */
1025 for (insn
= seq
; insn
; insn
= NEXT_INSN (insn
))
1027 || recog_memoized (insn
) == -1)
1033 /* Convert "if (a != b) x = a; else x = b" into "x = a" and
1034 "if (a == b) x = a; else x = b" into "x = b". */
1037 noce_try_move (struct noce_if_info
*if_info
)
1039 rtx cond
= if_info
->cond
;
1040 enum rtx_code code
= GET_CODE (cond
);
1044 if (code
!= NE
&& code
!= EQ
)
1047 /* This optimization isn't valid if either A or B could be a NaN
1048 or a signed zero. */
1049 if (HONOR_NANS (GET_MODE (if_info
->x
))
1050 || HONOR_SIGNED_ZEROS (GET_MODE (if_info
->x
)))
1053 /* Check whether the operands of the comparison are A and in
1055 if ((rtx_equal_p (if_info
->a
, XEXP (cond
, 0))
1056 && rtx_equal_p (if_info
->b
, XEXP (cond
, 1)))
1057 || (rtx_equal_p (if_info
->a
, XEXP (cond
, 1))
1058 && rtx_equal_p (if_info
->b
, XEXP (cond
, 0))))
1060 if (!rtx_interchangeable_p (if_info
->a
, if_info
->b
))
1063 y
= (code
== EQ
) ? if_info
->a
: if_info
->b
;
1065 /* Avoid generating the move if the source is the destination. */
1066 if (! rtx_equal_p (if_info
->x
, y
))
1069 noce_emit_move_insn (if_info
->x
, y
);
1070 seq
= end_ifcvt_sequence (if_info
);
1074 emit_insn_before_setloc (seq
, if_info
->jump
,
1075 INSN_LOCATION (if_info
->insn_a
));
1082 /* Convert "if (test) x = 1; else x = 0".
1084 Only try 0 and STORE_FLAG_VALUE here. Other combinations will be
1085 tried in noce_try_store_flag_constants after noce_try_cmove has had
1086 a go at the conversion. */
1089 noce_try_store_flag (struct noce_if_info
*if_info
)
1095 if (CONST_INT_P (if_info
->b
)
1096 && INTVAL (if_info
->b
) == STORE_FLAG_VALUE
1097 && if_info
->a
== const0_rtx
)
1099 else if (if_info
->b
== const0_rtx
1100 && CONST_INT_P (if_info
->a
)
1101 && INTVAL (if_info
->a
) == STORE_FLAG_VALUE
1102 && (reversed_comparison_code (if_info
->cond
, if_info
->jump
)
1110 target
= noce_emit_store_flag (if_info
, if_info
->x
, reversep
, 0);
1113 if (target
!= if_info
->x
)
1114 noce_emit_move_insn (if_info
->x
, target
);
1116 seq
= end_ifcvt_sequence (if_info
);
1120 emit_insn_before_setloc (seq
, if_info
->jump
,
1121 INSN_LOCATION (if_info
->insn_a
));
1131 /* Convert "if (test) x = a; else x = b", for A and B constant. */
1134 noce_try_store_flag_constants (struct noce_if_info
*if_info
)
1139 HOST_WIDE_INT itrue
, ifalse
, diff
, tmp
;
1140 int normalize
, can_reverse
;
1141 enum machine_mode mode
;
1143 if (CONST_INT_P (if_info
->a
)
1144 && CONST_INT_P (if_info
->b
))
1146 mode
= GET_MODE (if_info
->x
);
1147 ifalse
= INTVAL (if_info
->a
);
1148 itrue
= INTVAL (if_info
->b
);
1150 diff
= (unsigned HOST_WIDE_INT
) itrue
- ifalse
;
1151 /* Make sure we can represent the difference between the two values. */
1153 != ((ifalse
< 0) != (itrue
< 0) ? ifalse
< 0 : ifalse
< itrue
))
1156 diff
= trunc_int_for_mode (diff
, mode
);
1158 can_reverse
= (reversed_comparison_code (if_info
->cond
, if_info
->jump
)
1162 if (diff
== STORE_FLAG_VALUE
|| diff
== -STORE_FLAG_VALUE
)
1164 else if (ifalse
== 0 && exact_log2 (itrue
) >= 0
1165 && (STORE_FLAG_VALUE
== 1
1166 || if_info
->branch_cost
>= 2))
1168 else if (itrue
== 0 && exact_log2 (ifalse
) >= 0 && can_reverse
1169 && (STORE_FLAG_VALUE
== 1 || if_info
->branch_cost
>= 2))
1170 normalize
= 1, reversep
= 1;
1171 else if (itrue
== -1
1172 && (STORE_FLAG_VALUE
== -1
1173 || if_info
->branch_cost
>= 2))
1175 else if (ifalse
== -1 && can_reverse
1176 && (STORE_FLAG_VALUE
== -1 || if_info
->branch_cost
>= 2))
1177 normalize
= -1, reversep
= 1;
1178 else if ((if_info
->branch_cost
>= 2 && STORE_FLAG_VALUE
== -1)
1179 || if_info
->branch_cost
>= 3)
1186 tmp
= itrue
; itrue
= ifalse
; ifalse
= tmp
;
1187 diff
= trunc_int_for_mode (-(unsigned HOST_WIDE_INT
) diff
, mode
);
1191 target
= noce_emit_store_flag (if_info
, if_info
->x
, reversep
, normalize
);
1198 /* if (test) x = 3; else x = 4;
1199 => x = 3 + (test == 0); */
1200 if (diff
== STORE_FLAG_VALUE
|| diff
== -STORE_FLAG_VALUE
)
1202 target
= expand_simple_binop (mode
,
1203 (diff
== STORE_FLAG_VALUE
1205 gen_int_mode (ifalse
, mode
), target
,
1206 if_info
->x
, 0, OPTAB_WIDEN
);
1209 /* if (test) x = 8; else x = 0;
1210 => x = (test != 0) << 3; */
1211 else if (ifalse
== 0 && (tmp
= exact_log2 (itrue
)) >= 0)
1213 target
= expand_simple_binop (mode
, ASHIFT
,
1214 target
, GEN_INT (tmp
), if_info
->x
, 0,
1218 /* if (test) x = -1; else x = b;
1219 => x = -(test != 0) | b; */
1220 else if (itrue
== -1)
1222 target
= expand_simple_binop (mode
, IOR
,
1223 target
, gen_int_mode (ifalse
, mode
),
1224 if_info
->x
, 0, OPTAB_WIDEN
);
1227 /* if (test) x = a; else x = b;
1228 => x = (-(test != 0) & (b - a)) + a; */
1231 target
= expand_simple_binop (mode
, AND
,
1232 target
, gen_int_mode (diff
, mode
),
1233 if_info
->x
, 0, OPTAB_WIDEN
);
1235 target
= expand_simple_binop (mode
, PLUS
,
1236 target
, gen_int_mode (ifalse
, mode
),
1237 if_info
->x
, 0, OPTAB_WIDEN
);
1246 if (target
!= if_info
->x
)
1247 noce_emit_move_insn (if_info
->x
, target
);
1249 seq
= end_ifcvt_sequence (if_info
);
1253 emit_insn_before_setloc (seq
, if_info
->jump
,
1254 INSN_LOCATION (if_info
->insn_a
));
1261 /* Convert "if (test) foo++" into "foo += (test != 0)", and
1262 similarly for "foo--". */
1265 noce_try_addcc (struct noce_if_info
*if_info
)
1269 int subtract
, normalize
;
1271 if (GET_CODE (if_info
->a
) == PLUS
1272 && rtx_equal_p (XEXP (if_info
->a
, 0), if_info
->b
)
1273 && (reversed_comparison_code (if_info
->cond
, if_info
->jump
)
1276 rtx cond
= if_info
->cond
;
1277 enum rtx_code code
= reversed_comparison_code (cond
, if_info
->jump
);
1279 /* First try to use addcc pattern. */
1280 if (general_operand (XEXP (cond
, 0), VOIDmode
)
1281 && general_operand (XEXP (cond
, 1), VOIDmode
))
1284 target
= emit_conditional_add (if_info
->x
, code
,
1289 XEXP (if_info
->a
, 1),
1290 GET_MODE (if_info
->x
),
1291 (code
== LTU
|| code
== GEU
1292 || code
== LEU
|| code
== GTU
));
1295 if (target
!= if_info
->x
)
1296 noce_emit_move_insn (if_info
->x
, target
);
1298 seq
= end_ifcvt_sequence (if_info
);
1302 emit_insn_before_setloc (seq
, if_info
->jump
,
1303 INSN_LOCATION (if_info
->insn_a
));
1309 /* If that fails, construct conditional increment or decrement using
1311 if (if_info
->branch_cost
>= 2
1312 && (XEXP (if_info
->a
, 1) == const1_rtx
1313 || XEXP (if_info
->a
, 1) == constm1_rtx
))
1316 if (STORE_FLAG_VALUE
== INTVAL (XEXP (if_info
->a
, 1)))
1317 subtract
= 0, normalize
= 0;
1318 else if (-STORE_FLAG_VALUE
== INTVAL (XEXP (if_info
->a
, 1)))
1319 subtract
= 1, normalize
= 0;
1321 subtract
= 0, normalize
= INTVAL (XEXP (if_info
->a
, 1));
1324 target
= noce_emit_store_flag (if_info
,
1325 gen_reg_rtx (GET_MODE (if_info
->x
)),
1329 target
= expand_simple_binop (GET_MODE (if_info
->x
),
1330 subtract
? MINUS
: PLUS
,
1331 if_info
->b
, target
, if_info
->x
,
1335 if (target
!= if_info
->x
)
1336 noce_emit_move_insn (if_info
->x
, target
);
1338 seq
= end_ifcvt_sequence (if_info
);
1342 emit_insn_before_setloc (seq
, if_info
->jump
,
1343 INSN_LOCATION (if_info
->insn_a
));
1353 /* Convert "if (test) x = 0;" to "x &= -(test == 0);" */
1356 noce_try_store_flag_mask (struct noce_if_info
*if_info
)
1363 if ((if_info
->branch_cost
>= 2
1364 || STORE_FLAG_VALUE
== -1)
1365 && ((if_info
->a
== const0_rtx
1366 && rtx_equal_p (if_info
->b
, if_info
->x
))
1367 || ((reversep
= (reversed_comparison_code (if_info
->cond
,
1370 && if_info
->b
== const0_rtx
1371 && rtx_equal_p (if_info
->a
, if_info
->x
))))
1374 target
= noce_emit_store_flag (if_info
,
1375 gen_reg_rtx (GET_MODE (if_info
->x
)),
1378 target
= expand_simple_binop (GET_MODE (if_info
->x
), AND
,
1380 target
, if_info
->x
, 0,
1385 if (target
!= if_info
->x
)
1386 noce_emit_move_insn (if_info
->x
, target
);
1388 seq
= end_ifcvt_sequence (if_info
);
1392 emit_insn_before_setloc (seq
, if_info
->jump
,
1393 INSN_LOCATION (if_info
->insn_a
));
1403 /* Helper function for noce_try_cmove and noce_try_cmove_arith. */
1406 noce_emit_cmove (struct noce_if_info
*if_info
, rtx x
, enum rtx_code code
,
1407 rtx cmp_a
, rtx cmp_b
, rtx vfalse
, rtx vtrue
)
1409 rtx target ATTRIBUTE_UNUSED
;
1410 int unsignedp ATTRIBUTE_UNUSED
;
1412 /* If earliest == jump, try to build the cmove insn directly.
1413 This is helpful when combine has created some complex condition
1414 (like for alpha's cmovlbs) that we can't hope to regenerate
1415 through the normal interface. */
1417 if (if_info
->cond_earliest
== if_info
->jump
)
1421 tmp
= gen_rtx_fmt_ee (code
, GET_MODE (if_info
->cond
), cmp_a
, cmp_b
);
1422 tmp
= gen_rtx_IF_THEN_ELSE (GET_MODE (x
), tmp
, vtrue
, vfalse
);
1423 tmp
= gen_rtx_SET (VOIDmode
, x
, tmp
);
1426 tmp
= emit_insn (tmp
);
1428 if (recog_memoized (tmp
) >= 0)
1440 /* Don't even try if the comparison operands are weird. */
1441 if (! general_operand (cmp_a
, GET_MODE (cmp_a
))
1442 || ! general_operand (cmp_b
, GET_MODE (cmp_b
)))
1445 #if HAVE_conditional_move
1446 unsignedp
= (code
== LTU
|| code
== GEU
1447 || code
== LEU
|| code
== GTU
);
1449 target
= emit_conditional_move (x
, code
, cmp_a
, cmp_b
, VOIDmode
,
1450 vtrue
, vfalse
, GET_MODE (x
),
1455 /* We might be faced with a situation like:
1458 vtrue = (subreg:M (reg:N VTRUE) BYTE)
1459 vfalse = (subreg:M (reg:N VFALSE) BYTE)
1461 We can't do a conditional move in mode M, but it's possible that we
1462 could do a conditional move in mode N instead and take a subreg of
1465 If we can't create new pseudos, though, don't bother. */
1466 if (reload_completed
)
1469 if (GET_CODE (vtrue
) == SUBREG
&& GET_CODE (vfalse
) == SUBREG
)
1471 rtx reg_vtrue
= SUBREG_REG (vtrue
);
1472 rtx reg_vfalse
= SUBREG_REG (vfalse
);
1473 unsigned int byte_vtrue
= SUBREG_BYTE (vtrue
);
1474 unsigned int byte_vfalse
= SUBREG_BYTE (vfalse
);
1475 rtx promoted_target
;
1477 if (GET_MODE (reg_vtrue
) != GET_MODE (reg_vfalse
)
1478 || byte_vtrue
!= byte_vfalse
1479 || (SUBREG_PROMOTED_VAR_P (vtrue
)
1480 != SUBREG_PROMOTED_VAR_P (vfalse
))
1481 || (SUBREG_PROMOTED_GET (vtrue
)
1482 != SUBREG_PROMOTED_GET (vfalse
)))
1485 promoted_target
= gen_reg_rtx (GET_MODE (reg_vtrue
));
1487 target
= emit_conditional_move (promoted_target
, code
, cmp_a
, cmp_b
,
1488 VOIDmode
, reg_vtrue
, reg_vfalse
,
1489 GET_MODE (reg_vtrue
), unsignedp
);
1490 /* Nope, couldn't do it in that mode either. */
1494 target
= gen_rtx_SUBREG (GET_MODE (vtrue
), promoted_target
, byte_vtrue
);
1495 SUBREG_PROMOTED_VAR_P (target
) = SUBREG_PROMOTED_VAR_P (vtrue
);
1496 SUBREG_PROMOTED_SET (target
, SUBREG_PROMOTED_GET (vtrue
));
1497 emit_move_insn (x
, target
);
1503 /* We'll never get here, as noce_process_if_block doesn't call the
1504 functions involved. Ifdef code, however, should be discouraged
1505 because it leads to typos in the code not selected. However,
1506 emit_conditional_move won't exist either. */
1511 /* Try only simple constants and registers here. More complex cases
1512 are handled in noce_try_cmove_arith after noce_try_store_flag_arith
1513 has had a go at it. */
1516 noce_try_cmove (struct noce_if_info
*if_info
)
1522 if ((CONSTANT_P (if_info
->a
) || register_operand (if_info
->a
, VOIDmode
))
1523 && (CONSTANT_P (if_info
->b
) || register_operand (if_info
->b
, VOIDmode
)))
1527 code
= GET_CODE (if_info
->cond
);
1528 target
= noce_emit_cmove (if_info
, if_info
->x
, code
,
1529 XEXP (if_info
->cond
, 0),
1530 XEXP (if_info
->cond
, 1),
1531 if_info
->a
, if_info
->b
);
1535 if (target
!= if_info
->x
)
1536 noce_emit_move_insn (if_info
->x
, target
);
1538 seq
= end_ifcvt_sequence (if_info
);
1542 emit_insn_before_setloc (seq
, if_info
->jump
,
1543 INSN_LOCATION (if_info
->insn_a
));
1556 /* Try more complex cases involving conditional_move. */
1559 noce_try_cmove_arith (struct noce_if_info
*if_info
)
1571 /* A conditional move from two memory sources is equivalent to a
1572 conditional on their addresses followed by a load. Don't do this
1573 early because it'll screw alias analysis. Note that we've
1574 already checked for no side effects. */
1575 /* ??? FIXME: Magic number 5. */
1576 if (cse_not_expected
1577 && MEM_P (a
) && MEM_P (b
)
1578 && MEM_ADDR_SPACE (a
) == MEM_ADDR_SPACE (b
)
1579 && if_info
->branch_cost
>= 5)
1581 enum machine_mode address_mode
= get_address_mode (a
);
1585 x
= gen_reg_rtx (address_mode
);
1589 /* ??? We could handle this if we knew that a load from A or B could
1590 not trap or fault. This is also true if we've already loaded
1591 from the address along the path from ENTRY. */
1592 else if (may_trap_or_fault_p (a
) || may_trap_or_fault_p (b
))
1595 /* if (test) x = a + b; else x = c - d;
1602 code
= GET_CODE (if_info
->cond
);
1603 insn_a
= if_info
->insn_a
;
1604 insn_b
= if_info
->insn_b
;
1606 /* Total insn_rtx_cost should be smaller than branch cost. Exit
1607 if insn_rtx_cost can't be estimated. */
1611 = insn_rtx_cost (PATTERN (insn_a
),
1612 optimize_bb_for_speed_p (BLOCK_FOR_INSN (insn_a
)));
1613 if (insn_cost
== 0 || insn_cost
> COSTS_N_INSNS (if_info
->branch_cost
))
1622 += insn_rtx_cost (PATTERN (insn_b
),
1623 optimize_bb_for_speed_p (BLOCK_FOR_INSN (insn_b
)));
1624 if (insn_cost
== 0 || insn_cost
> COSTS_N_INSNS (if_info
->branch_cost
))
1628 /* Possibly rearrange operands to make things come out more natural. */
1629 if (reversed_comparison_code (if_info
->cond
, if_info
->jump
) != UNKNOWN
)
1632 if (rtx_equal_p (b
, x
))
1634 else if (general_operand (b
, GET_MODE (b
)))
1639 code
= reversed_comparison_code (if_info
->cond
, if_info
->jump
);
1640 tmp
= a
, a
= b
, b
= tmp
;
1641 tmp
= insn_a
, insn_a
= insn_b
, insn_b
= tmp
;
1650 /* If either operand is complex, load it into a register first.
1651 The best way to do this is to copy the original insn. In this
1652 way we preserve any clobbers etc that the insn may have had.
1653 This is of course not possible in the IS_MEM case. */
1654 if (! general_operand (a
, GET_MODE (a
)))
1660 tmp
= gen_reg_rtx (GET_MODE (a
));
1661 tmp
= emit_insn (gen_rtx_SET (VOIDmode
, tmp
, a
));
1664 goto end_seq_and_fail
;
1667 a
= gen_reg_rtx (GET_MODE (a
));
1668 tmp
= copy_rtx (insn_a
);
1669 set
= single_set (tmp
);
1671 tmp
= emit_insn (PATTERN (tmp
));
1673 if (recog_memoized (tmp
) < 0)
1674 goto end_seq_and_fail
;
1676 if (! general_operand (b
, GET_MODE (b
)))
1682 tmp
= gen_reg_rtx (GET_MODE (b
));
1683 tmp
= gen_rtx_SET (VOIDmode
, tmp
, b
);
1686 goto end_seq_and_fail
;
1689 b
= gen_reg_rtx (GET_MODE (b
));
1690 tmp
= copy_rtx (insn_b
);
1691 set
= single_set (tmp
);
1693 tmp
= PATTERN (tmp
);
1696 /* If insn to set up A clobbers any registers B depends on, try to
1697 swap insn that sets up A with the one that sets up B. If even
1698 that doesn't help, punt. */
1699 last
= get_last_insn ();
1700 if (last
&& modified_in_p (orig_b
, last
))
1702 tmp
= emit_insn_before (tmp
, get_insns ());
1703 if (modified_in_p (orig_a
, tmp
))
1704 goto end_seq_and_fail
;
1707 tmp
= emit_insn (tmp
);
1709 if (recog_memoized (tmp
) < 0)
1710 goto end_seq_and_fail
;
1713 target
= noce_emit_cmove (if_info
, x
, code
, XEXP (if_info
->cond
, 0),
1714 XEXP (if_info
->cond
, 1), a
, b
);
1717 goto end_seq_and_fail
;
1719 /* If we're handling a memory for above, emit the load now. */
1722 tmp
= gen_rtx_MEM (GET_MODE (if_info
->x
), target
);
1724 /* Copy over flags as appropriate. */
1725 if (MEM_VOLATILE_P (if_info
->a
) || MEM_VOLATILE_P (if_info
->b
))
1726 MEM_VOLATILE_P (tmp
) = 1;
1727 if (MEM_ALIAS_SET (if_info
->a
) == MEM_ALIAS_SET (if_info
->b
))
1728 set_mem_alias_set (tmp
, MEM_ALIAS_SET (if_info
->a
));
1730 MIN (MEM_ALIGN (if_info
->a
), MEM_ALIGN (if_info
->b
)));
1732 gcc_assert (MEM_ADDR_SPACE (if_info
->a
) == MEM_ADDR_SPACE (if_info
->b
));
1733 set_mem_addr_space (tmp
, MEM_ADDR_SPACE (if_info
->a
));
1735 noce_emit_move_insn (if_info
->x
, tmp
);
1737 else if (target
!= x
)
1738 noce_emit_move_insn (x
, target
);
1740 tmp
= end_ifcvt_sequence (if_info
);
1744 emit_insn_before_setloc (tmp
, if_info
->jump
, INSN_LOCATION (if_info
->insn_a
));
1752 /* For most cases, the simplified condition we found is the best
1753 choice, but this is not the case for the min/max/abs transforms.
1754 For these we wish to know that it is A or B in the condition. */
1757 noce_get_alt_condition (struct noce_if_info
*if_info
, rtx target
,
1758 rtx_insn
**earliest
)
1764 /* If target is already mentioned in the known condition, return it. */
1765 if (reg_mentioned_p (target
, if_info
->cond
))
1767 *earliest
= if_info
->cond_earliest
;
1768 return if_info
->cond
;
1771 set
= pc_set (if_info
->jump
);
1772 cond
= XEXP (SET_SRC (set
), 0);
1774 = GET_CODE (XEXP (SET_SRC (set
), 2)) == LABEL_REF
1775 && XEXP (XEXP (SET_SRC (set
), 2), 0) == JUMP_LABEL (if_info
->jump
);
1776 if (if_info
->then_else_reversed
)
1779 /* If we're looking for a constant, try to make the conditional
1780 have that constant in it. There are two reasons why it may
1781 not have the constant we want:
1783 1. GCC may have needed to put the constant in a register, because
1784 the target can't compare directly against that constant. For
1785 this case, we look for a SET immediately before the comparison
1786 that puts a constant in that register.
1788 2. GCC may have canonicalized the conditional, for example
1789 replacing "if x < 4" with "if x <= 3". We can undo that (or
1790 make equivalent types of changes) to get the constants we need
1791 if they're off by one in the right direction. */
1793 if (CONST_INT_P (target
))
1795 enum rtx_code code
= GET_CODE (if_info
->cond
);
1796 rtx op_a
= XEXP (if_info
->cond
, 0);
1797 rtx op_b
= XEXP (if_info
->cond
, 1);
1800 /* First, look to see if we put a constant in a register. */
1801 prev_insn
= prev_nonnote_insn (if_info
->cond_earliest
);
1803 && BLOCK_FOR_INSN (prev_insn
)
1804 == BLOCK_FOR_INSN (if_info
->cond_earliest
)
1805 && INSN_P (prev_insn
)
1806 && GET_CODE (PATTERN (prev_insn
)) == SET
)
1808 rtx src
= find_reg_equal_equiv_note (prev_insn
);
1810 src
= SET_SRC (PATTERN (prev_insn
));
1811 if (CONST_INT_P (src
))
1813 if (rtx_equal_p (op_a
, SET_DEST (PATTERN (prev_insn
))))
1815 else if (rtx_equal_p (op_b
, SET_DEST (PATTERN (prev_insn
))))
1818 if (CONST_INT_P (op_a
))
1823 code
= swap_condition (code
);
1828 /* Now, look to see if we can get the right constant by
1829 adjusting the conditional. */
1830 if (CONST_INT_P (op_b
))
1832 HOST_WIDE_INT desired_val
= INTVAL (target
);
1833 HOST_WIDE_INT actual_val
= INTVAL (op_b
);
1838 if (actual_val
== desired_val
+ 1)
1841 op_b
= GEN_INT (desired_val
);
1845 if (actual_val
== desired_val
- 1)
1848 op_b
= GEN_INT (desired_val
);
1852 if (actual_val
== desired_val
- 1)
1855 op_b
= GEN_INT (desired_val
);
1859 if (actual_val
== desired_val
+ 1)
1862 op_b
= GEN_INT (desired_val
);
1870 /* If we made any changes, generate a new conditional that is
1871 equivalent to what we started with, but has the right
1873 if (code
!= GET_CODE (if_info
->cond
)
1874 || op_a
!= XEXP (if_info
->cond
, 0)
1875 || op_b
!= XEXP (if_info
->cond
, 1))
1877 cond
= gen_rtx_fmt_ee (code
, GET_MODE (cond
), op_a
, op_b
);
1878 *earliest
= if_info
->cond_earliest
;
1883 cond
= canonicalize_condition (if_info
->jump
, cond
, reverse
,
1884 earliest
, target
, false, true);
1885 if (! cond
|| ! reg_mentioned_p (target
, cond
))
1888 /* We almost certainly searched back to a different place.
1889 Need to re-verify correct lifetimes. */
1891 /* X may not be mentioned in the range (cond_earliest, jump]. */
1892 for (insn
= if_info
->jump
; insn
!= *earliest
; insn
= PREV_INSN (insn
))
1893 if (INSN_P (insn
) && reg_overlap_mentioned_p (if_info
->x
, PATTERN (insn
)))
1896 /* A and B may not be modified in the range [cond_earliest, jump). */
1897 for (insn
= *earliest
; insn
!= if_info
->jump
; insn
= NEXT_INSN (insn
))
1899 && (modified_in_p (if_info
->a
, insn
)
1900 || modified_in_p (if_info
->b
, insn
)))
1906 /* Convert "if (a < b) x = a; else x = b;" to "x = min(a, b);", etc. */
1909 noce_try_minmax (struct noce_if_info
*if_info
)
1912 rtx_insn
*earliest
, *seq
;
1913 enum rtx_code code
, op
;
1916 /* ??? Reject modes with NaNs or signed zeros since we don't know how
1917 they will be resolved with an SMIN/SMAX. It wouldn't be too hard
1918 to get the target to tell us... */
1919 if (HONOR_SIGNED_ZEROS (GET_MODE (if_info
->x
))
1920 || HONOR_NANS (GET_MODE (if_info
->x
)))
1923 cond
= noce_get_alt_condition (if_info
, if_info
->a
, &earliest
);
1927 /* Verify the condition is of the form we expect, and canonicalize
1928 the comparison code. */
1929 code
= GET_CODE (cond
);
1930 if (rtx_equal_p (XEXP (cond
, 0), if_info
->a
))
1932 if (! rtx_equal_p (XEXP (cond
, 1), if_info
->b
))
1935 else if (rtx_equal_p (XEXP (cond
, 1), if_info
->a
))
1937 if (! rtx_equal_p (XEXP (cond
, 0), if_info
->b
))
1939 code
= swap_condition (code
);
1944 /* Determine what sort of operation this is. Note that the code is for
1945 a taken branch, so the code->operation mapping appears backwards. */
1978 target
= expand_simple_binop (GET_MODE (if_info
->x
), op
,
1979 if_info
->a
, if_info
->b
,
1980 if_info
->x
, unsignedp
, OPTAB_WIDEN
);
1986 if (target
!= if_info
->x
)
1987 noce_emit_move_insn (if_info
->x
, target
);
1989 seq
= end_ifcvt_sequence (if_info
);
1993 emit_insn_before_setloc (seq
, if_info
->jump
, INSN_LOCATION (if_info
->insn_a
));
1994 if_info
->cond
= cond
;
1995 if_info
->cond_earliest
= earliest
;
2000 /* Convert "if (a < 0) x = -a; else x = a;" to "x = abs(a);",
2001 "if (a < 0) x = ~a; else x = a;" to "x = one_cmpl_abs(a);",
2005 noce_try_abs (struct noce_if_info
*if_info
)
2007 rtx cond
, target
, a
, b
, c
;
2008 rtx_insn
*earliest
, *seq
;
2010 bool one_cmpl
= false;
2012 /* Reject modes with signed zeros. */
2013 if (HONOR_SIGNED_ZEROS (GET_MODE (if_info
->x
)))
2016 /* Recognize A and B as constituting an ABS or NABS. The canonical
2017 form is a branch around the negation, taken when the object is the
2018 first operand of a comparison against 0 that evaluates to true. */
2021 if (GET_CODE (a
) == NEG
&& rtx_equal_p (XEXP (a
, 0), b
))
2023 else if (GET_CODE (b
) == NEG
&& rtx_equal_p (XEXP (b
, 0), a
))
2025 c
= a
; a
= b
; b
= c
;
2028 else if (GET_CODE (a
) == NOT
&& rtx_equal_p (XEXP (a
, 0), b
))
2033 else if (GET_CODE (b
) == NOT
&& rtx_equal_p (XEXP (b
, 0), a
))
2035 c
= a
; a
= b
; b
= c
;
2042 cond
= noce_get_alt_condition (if_info
, b
, &earliest
);
2046 /* Verify the condition is of the form we expect. */
2047 if (rtx_equal_p (XEXP (cond
, 0), b
))
2049 else if (rtx_equal_p (XEXP (cond
, 1), b
))
2057 /* Verify that C is zero. Search one step backward for a
2058 REG_EQUAL note or a simple source if necessary. */
2061 rtx set
, insn
= prev_nonnote_insn (earliest
);
2063 && BLOCK_FOR_INSN (insn
) == BLOCK_FOR_INSN (earliest
)
2064 && (set
= single_set (insn
))
2065 && rtx_equal_p (SET_DEST (set
), c
))
2067 rtx note
= find_reg_equal_equiv_note (insn
);
2077 && GET_CODE (XEXP (c
, 0)) == SYMBOL_REF
2078 && CONSTANT_POOL_ADDRESS_P (XEXP (c
, 0)))
2079 c
= get_pool_constant (XEXP (c
, 0));
2081 /* Work around funny ideas get_condition has wrt canonicalization.
2082 Note that these rtx constants are known to be CONST_INT, and
2083 therefore imply integer comparisons. */
2084 if (c
== constm1_rtx
&& GET_CODE (cond
) == GT
)
2086 else if (c
== const1_rtx
&& GET_CODE (cond
) == LT
)
2088 else if (c
!= CONST0_RTX (GET_MODE (b
)))
2091 /* Determine what sort of operation this is. */
2092 switch (GET_CODE (cond
))
2111 target
= expand_one_cmpl_abs_nojump (GET_MODE (if_info
->x
), b
,
2114 target
= expand_abs_nojump (GET_MODE (if_info
->x
), b
, if_info
->x
, 1);
2116 /* ??? It's a quandary whether cmove would be better here, especially
2117 for integers. Perhaps combine will clean things up. */
2118 if (target
&& negate
)
2121 target
= expand_simple_unop (GET_MODE (target
), NOT
, target
,
2124 target
= expand_simple_unop (GET_MODE (target
), NEG
, target
,
2134 if (target
!= if_info
->x
)
2135 noce_emit_move_insn (if_info
->x
, target
);
2137 seq
= end_ifcvt_sequence (if_info
);
2141 emit_insn_before_setloc (seq
, if_info
->jump
, INSN_LOCATION (if_info
->insn_a
));
2142 if_info
->cond
= cond
;
2143 if_info
->cond_earliest
= earliest
;
2148 /* Convert "if (m < 0) x = b; else x = 0;" to "x = (m >> C) & b;". */
2151 noce_try_sign_mask (struct noce_if_info
*if_info
)
2155 enum machine_mode mode
;
2157 bool t_unconditional
;
2159 cond
= if_info
->cond
;
2160 code
= GET_CODE (cond
);
2165 if (if_info
->a
== const0_rtx
)
2167 if ((code
== LT
&& c
== const0_rtx
)
2168 || (code
== LE
&& c
== constm1_rtx
))
2171 else if (if_info
->b
== const0_rtx
)
2173 if ((code
== GE
&& c
== const0_rtx
)
2174 || (code
== GT
&& c
== constm1_rtx
))
2178 if (! t
|| side_effects_p (t
))
2181 /* We currently don't handle different modes. */
2182 mode
= GET_MODE (t
);
2183 if (GET_MODE (m
) != mode
)
2186 /* This is only profitable if T is unconditionally executed/evaluated in the
2187 original insn sequence or T is cheap. The former happens if B is the
2188 non-zero (T) value and if INSN_B was taken from TEST_BB, or there was no
2189 INSN_B which can happen for e.g. conditional stores to memory. For the
2190 cost computation use the block TEST_BB where the evaluation will end up
2191 after the transformation. */
2194 && (if_info
->insn_b
== NULL_RTX
2195 || BLOCK_FOR_INSN (if_info
->insn_b
) == if_info
->test_bb
));
2196 if (!(t_unconditional
2197 || (set_src_cost (t
, optimize_bb_for_speed_p (if_info
->test_bb
))
2198 < COSTS_N_INSNS (2))))
2202 /* Use emit_store_flag to generate "m < 0 ? -1 : 0" instead of expanding
2203 "(signed) m >> 31" directly. This benefits targets with specialized
2204 insns to obtain the signmask, but still uses ashr_optab otherwise. */
2205 m
= emit_store_flag (gen_reg_rtx (mode
), LT
, m
, const0_rtx
, mode
, 0, -1);
2206 t
= m
? expand_binop (mode
, and_optab
, m
, t
, NULL_RTX
, 0, OPTAB_DIRECT
)
2215 noce_emit_move_insn (if_info
->x
, t
);
2217 seq
= end_ifcvt_sequence (if_info
);
2221 emit_insn_before_setloc (seq
, if_info
->jump
, INSN_LOCATION (if_info
->insn_a
));
2226 /* Optimize away "if (x & C) x |= C" and similar bit manipulation
2230 noce_try_bitop (struct noce_if_info
*if_info
)
2232 rtx cond
, x
, a
, result
;
2234 enum machine_mode mode
;
2239 cond
= if_info
->cond
;
2240 code
= GET_CODE (cond
);
2242 /* Check for no else condition. */
2243 if (! rtx_equal_p (x
, if_info
->b
))
2246 /* Check for a suitable condition. */
2247 if (code
!= NE
&& code
!= EQ
)
2249 if (XEXP (cond
, 1) != const0_rtx
)
2251 cond
= XEXP (cond
, 0);
2253 /* ??? We could also handle AND here. */
2254 if (GET_CODE (cond
) == ZERO_EXTRACT
)
2256 if (XEXP (cond
, 1) != const1_rtx
2257 || !CONST_INT_P (XEXP (cond
, 2))
2258 || ! rtx_equal_p (x
, XEXP (cond
, 0)))
2260 bitnum
= INTVAL (XEXP (cond
, 2));
2261 mode
= GET_MODE (x
);
2262 if (BITS_BIG_ENDIAN
)
2263 bitnum
= GET_MODE_BITSIZE (mode
) - 1 - bitnum
;
2264 if (bitnum
< 0 || bitnum
>= HOST_BITS_PER_WIDE_INT
)
2271 if (GET_CODE (a
) == IOR
|| GET_CODE (a
) == XOR
)
2273 /* Check for "if (X & C) x = x op C". */
2274 if (! rtx_equal_p (x
, XEXP (a
, 0))
2275 || !CONST_INT_P (XEXP (a
, 1))
2276 || (INTVAL (XEXP (a
, 1)) & GET_MODE_MASK (mode
))
2277 != (unsigned HOST_WIDE_INT
) 1 << bitnum
)
2280 /* if ((x & C) == 0) x |= C; is transformed to x |= C. */
2281 /* if ((x & C) != 0) x |= C; is transformed to nothing. */
2282 if (GET_CODE (a
) == IOR
)
2283 result
= (code
== NE
) ? a
: NULL_RTX
;
2284 else if (code
== NE
)
2286 /* if ((x & C) == 0) x ^= C; is transformed to x |= C. */
2287 result
= gen_int_mode ((HOST_WIDE_INT
) 1 << bitnum
, mode
);
2288 result
= simplify_gen_binary (IOR
, mode
, x
, result
);
2292 /* if ((x & C) != 0) x ^= C; is transformed to x &= ~C. */
2293 result
= gen_int_mode (~((HOST_WIDE_INT
) 1 << bitnum
), mode
);
2294 result
= simplify_gen_binary (AND
, mode
, x
, result
);
2297 else if (GET_CODE (a
) == AND
)
2299 /* Check for "if (X & C) x &= ~C". */
2300 if (! rtx_equal_p (x
, XEXP (a
, 0))
2301 || !CONST_INT_P (XEXP (a
, 1))
2302 || (INTVAL (XEXP (a
, 1)) & GET_MODE_MASK (mode
))
2303 != (~((HOST_WIDE_INT
) 1 << bitnum
) & GET_MODE_MASK (mode
)))
2306 /* if ((x & C) == 0) x &= ~C; is transformed to nothing. */
2307 /* if ((x & C) != 0) x &= ~C; is transformed to x &= ~C. */
2308 result
= (code
== EQ
) ? a
: NULL_RTX
;
2316 noce_emit_move_insn (x
, result
);
2317 seq
= end_ifcvt_sequence (if_info
);
2321 emit_insn_before_setloc (seq
, if_info
->jump
,
2322 INSN_LOCATION (if_info
->insn_a
));
2328 /* Similar to get_condition, only the resulting condition must be
2329 valid at JUMP, instead of at EARLIEST.
2331 If THEN_ELSE_REVERSED is true, the fallthrough does not go to the
2332 THEN block of the caller, and we have to reverse the condition. */
2335 noce_get_condition (rtx_insn
*jump
, rtx_insn
**earliest
, bool then_else_reversed
)
2340 if (! any_condjump_p (jump
))
2343 set
= pc_set (jump
);
2345 /* If this branches to JUMP_LABEL when the condition is false,
2346 reverse the condition. */
2347 reverse
= (GET_CODE (XEXP (SET_SRC (set
), 2)) == LABEL_REF
2348 && XEXP (XEXP (SET_SRC (set
), 2), 0) == JUMP_LABEL (jump
));
2350 /* We may have to reverse because the caller's if block is not canonical,
2351 i.e. the THEN block isn't the fallthrough block for the TEST block
2352 (see find_if_header). */
2353 if (then_else_reversed
)
2356 /* If the condition variable is a register and is MODE_INT, accept it. */
2358 cond
= XEXP (SET_SRC (set
), 0);
2359 tmp
= XEXP (cond
, 0);
2360 if (REG_P (tmp
) && GET_MODE_CLASS (GET_MODE (tmp
)) == MODE_INT
2361 && (GET_MODE (tmp
) != BImode
2362 || !targetm
.small_register_classes_for_mode_p (BImode
)))
2367 cond
= gen_rtx_fmt_ee (reverse_condition (GET_CODE (cond
)),
2368 GET_MODE (cond
), tmp
, XEXP (cond
, 1));
2372 /* Otherwise, fall back on canonicalize_condition to do the dirty
2373 work of manipulating MODE_CC values and COMPARE rtx codes. */
2374 tmp
= canonicalize_condition (jump
, cond
, reverse
, earliest
,
2375 NULL_RTX
, false, true);
2377 /* We don't handle side-effects in the condition, like handling
2378 REG_INC notes and making sure no duplicate conditions are emitted. */
2379 if (tmp
!= NULL_RTX
&& side_effects_p (tmp
))
2385 /* Return true if OP is ok for if-then-else processing. */
2388 noce_operand_ok (const_rtx op
)
2390 if (side_effects_p (op
))
2393 /* We special-case memories, so handle any of them with
2394 no address side effects. */
2396 return ! side_effects_p (XEXP (op
, 0));
2398 return ! may_trap_p (op
);
2401 /* Return true if a write into MEM may trap or fault. */
2404 noce_mem_write_may_trap_or_fault_p (const_rtx mem
)
2408 if (MEM_READONLY_P (mem
))
2411 if (may_trap_or_fault_p (mem
))
2414 addr
= XEXP (mem
, 0);
2416 /* Call target hook to avoid the effects of -fpic etc.... */
2417 addr
= targetm
.delegitimize_address (addr
);
2420 switch (GET_CODE (addr
))
2428 addr
= XEXP (addr
, 0);
2432 addr
= XEXP (addr
, 1);
2435 if (CONST_INT_P (XEXP (addr
, 1)))
2436 addr
= XEXP (addr
, 0);
2443 if (SYMBOL_REF_DECL (addr
)
2444 && decl_readonly_section (SYMBOL_REF_DECL (addr
), 0))
2454 /* Return whether we can use store speculation for MEM. TOP_BB is the
2455 basic block above the conditional block where we are considering
2456 doing the speculative store. We look for whether MEM is set
2457 unconditionally later in the function. */
2460 noce_can_store_speculate_p (basic_block top_bb
, const_rtx mem
)
2462 basic_block dominator
;
2464 for (dominator
= get_immediate_dominator (CDI_POST_DOMINATORS
, top_bb
);
2466 dominator
= get_immediate_dominator (CDI_POST_DOMINATORS
, dominator
))
2470 FOR_BB_INSNS (dominator
, insn
)
2472 /* If we see something that might be a memory barrier, we
2473 have to stop looking. Even if the MEM is set later in
2474 the function, we still don't want to set it
2475 unconditionally before the barrier. */
2477 && (volatile_insn_p (PATTERN (insn
))
2478 || (CALL_P (insn
) && (!RTL_CONST_CALL_P (insn
)))))
2481 if (memory_must_be_modified_in_insn_p (mem
, insn
))
2483 if (modified_in_p (XEXP (mem
, 0), insn
))
2492 /* Given a simple IF-THEN-JOIN or IF-THEN-ELSE-JOIN block, attempt to convert
2493 it without using conditional execution. Return TRUE if we were successful
2494 at converting the block. */
2497 noce_process_if_block (struct noce_if_info
*if_info
)
2499 basic_block test_bb
= if_info
->test_bb
; /* test block */
2500 basic_block then_bb
= if_info
->then_bb
; /* THEN */
2501 basic_block else_bb
= if_info
->else_bb
; /* ELSE or NULL */
2502 basic_block join_bb
= if_info
->join_bb
; /* JOIN */
2503 rtx_insn
*jump
= if_info
->jump
;
2504 rtx cond
= if_info
->cond
;
2505 rtx_insn
*insn_a
, *insn_b
;
2507 rtx orig_x
, x
, a
, b
;
2509 /* We're looking for patterns of the form
2511 (1) if (...) x = a; else x = b;
2512 (2) x = b; if (...) x = a;
2513 (3) if (...) x = a; // as if with an initial x = x.
2515 The later patterns require jumps to be more expensive.
2517 ??? For future expansion, look for multiple X in such patterns. */
2519 /* Look for one of the potential sets. */
2520 insn_a
= first_active_insn (then_bb
);
2522 || insn_a
!= last_active_insn (then_bb
, FALSE
)
2523 || (set_a
= single_set (insn_a
)) == NULL_RTX
)
2526 x
= SET_DEST (set_a
);
2527 a
= SET_SRC (set_a
);
2529 /* Look for the other potential set. Make sure we've got equivalent
2531 /* ??? This is overconservative. Storing to two different mems is
2532 as easy as conditionally computing the address. Storing to a
2533 single mem merely requires a scratch memory to use as one of the
2534 destination addresses; often the memory immediately below the
2535 stack pointer is available for this. */
2539 insn_b
= first_active_insn (else_bb
);
2541 || insn_b
!= last_active_insn (else_bb
, FALSE
)
2542 || (set_b
= single_set (insn_b
)) == NULL_RTX
2543 || ! rtx_interchangeable_p (x
, SET_DEST (set_b
)))
2548 insn_b
= prev_nonnote_nondebug_insn (if_info
->cond_earliest
);
2549 /* We're going to be moving the evaluation of B down from above
2550 COND_EARLIEST to JUMP. Make sure the relevant data is still
2553 || BLOCK_FOR_INSN (insn_b
) != BLOCK_FOR_INSN (if_info
->cond_earliest
)
2554 || !NONJUMP_INSN_P (insn_b
)
2555 || (set_b
= single_set (insn_b
)) == NULL_RTX
2556 || ! rtx_interchangeable_p (x
, SET_DEST (set_b
))
2557 || ! noce_operand_ok (SET_SRC (set_b
))
2558 || reg_overlap_mentioned_p (x
, SET_SRC (set_b
))
2559 || modified_between_p (SET_SRC (set_b
), insn_b
, jump
)
2560 /* Avoid extending the lifetime of hard registers on small
2561 register class machines. */
2562 || (REG_P (SET_SRC (set_b
))
2563 && HARD_REGISTER_P (SET_SRC (set_b
))
2564 && targetm
.small_register_classes_for_mode_p
2565 (GET_MODE (SET_SRC (set_b
))))
2566 /* Likewise with X. In particular this can happen when
2567 noce_get_condition looks farther back in the instruction
2568 stream than one might expect. */
2569 || reg_overlap_mentioned_p (x
, cond
)
2570 || reg_overlap_mentioned_p (x
, a
)
2571 || modified_between_p (x
, insn_b
, jump
))
2578 /* If x has side effects then only the if-then-else form is safe to
2579 convert. But even in that case we would need to restore any notes
2580 (such as REG_INC) at then end. That can be tricky if
2581 noce_emit_move_insn expands to more than one insn, so disable the
2582 optimization entirely for now if there are side effects. */
2583 if (side_effects_p (x
))
2586 b
= (set_b
? SET_SRC (set_b
) : x
);
2588 /* Only operate on register destinations, and even then avoid extending
2589 the lifetime of hard registers on small register class machines. */
2592 || (HARD_REGISTER_P (x
)
2593 && targetm
.small_register_classes_for_mode_p (GET_MODE (x
))))
2595 if (GET_MODE (x
) == BLKmode
)
2598 if (GET_CODE (x
) == ZERO_EXTRACT
2599 && (!CONST_INT_P (XEXP (x
, 1))
2600 || !CONST_INT_P (XEXP (x
, 2))))
2603 x
= gen_reg_rtx (GET_MODE (GET_CODE (x
) == STRICT_LOW_PART
2604 ? XEXP (x
, 0) : x
));
2607 /* Don't operate on sources that may trap or are volatile. */
2608 if (! noce_operand_ok (a
) || ! noce_operand_ok (b
))
2612 /* Set up the info block for our subroutines. */
2613 if_info
->insn_a
= insn_a
;
2614 if_info
->insn_b
= insn_b
;
2619 /* Try optimizations in some approximation of a useful order. */
2620 /* ??? Should first look to see if X is live incoming at all. If it
2621 isn't, we don't need anything but an unconditional set. */
2623 /* Look and see if A and B are really the same. Avoid creating silly
2624 cmove constructs that no one will fix up later. */
2625 if (rtx_interchangeable_p (a
, b
))
2627 /* If we have an INSN_B, we don't have to create any new rtl. Just
2628 move the instruction that we already have. If we don't have an
2629 INSN_B, that means that A == X, and we've got a noop move. In
2630 that case don't do anything and let the code below delete INSN_A. */
2631 if (insn_b
&& else_bb
)
2635 if (else_bb
&& insn_b
== BB_END (else_bb
))
2636 BB_END (else_bb
) = PREV_INSN (insn_b
);
2637 reorder_insns (insn_b
, insn_b
, PREV_INSN (jump
));
2639 /* If there was a REG_EQUAL note, delete it since it may have been
2640 true due to this insn being after a jump. */
2641 if ((note
= find_reg_note (insn_b
, REG_EQUAL
, NULL_RTX
)) != 0)
2642 remove_note (insn_b
, note
);
2646 /* If we have "x = b; if (...) x = a;", and x has side-effects, then
2647 x must be executed twice. */
2648 else if (insn_b
&& side_effects_p (orig_x
))
2655 if (!set_b
&& MEM_P (orig_x
))
2657 /* Disallow the "if (...) x = a;" form (implicit "else x = x;")
2658 for optimizations if writing to x may trap or fault,
2659 i.e. it's a memory other than a static var or a stack slot,
2660 is misaligned on strict aligned machines or is read-only. If
2661 x is a read-only memory, then the program is valid only if we
2662 avoid the store into it. If there are stores on both the
2663 THEN and ELSE arms, then we can go ahead with the conversion;
2664 either the program is broken, or the condition is always
2665 false such that the other memory is selected. */
2666 if (noce_mem_write_may_trap_or_fault_p (orig_x
))
2669 /* Avoid store speculation: given "if (...) x = a" where x is a
2670 MEM, we only want to do the store if x is always set
2671 somewhere in the function. This avoids cases like
2672 if (pthread_mutex_trylock(mutex))
2674 where we only want global_variable to be changed if the mutex
2675 is held. FIXME: This should ideally be expressed directly in
2677 if (!noce_can_store_speculate_p (test_bb
, orig_x
))
2681 if (noce_try_move (if_info
))
2683 if (noce_try_store_flag (if_info
))
2685 if (noce_try_bitop (if_info
))
2687 if (noce_try_minmax (if_info
))
2689 if (noce_try_abs (if_info
))
2691 if (HAVE_conditional_move
2692 && noce_try_cmove (if_info
))
2694 if (! targetm
.have_conditional_execution ())
2696 if (noce_try_store_flag_constants (if_info
))
2698 if (noce_try_addcc (if_info
))
2700 if (noce_try_store_flag_mask (if_info
))
2702 if (HAVE_conditional_move
2703 && noce_try_cmove_arith (if_info
))
2705 if (noce_try_sign_mask (if_info
))
2709 if (!else_bb
&& set_b
)
2721 /* If we used a temporary, fix it up now. */
2727 noce_emit_move_insn (orig_x
, x
);
2729 set_used_flags (orig_x
);
2730 unshare_all_rtl_in_chain (seq
);
2733 emit_insn_before_setloc (seq
, BB_END (test_bb
), INSN_LOCATION (insn_a
));
2736 /* The original THEN and ELSE blocks may now be removed. The test block
2737 must now jump to the join block. If the test block and the join block
2738 can be merged, do so. */
2741 delete_basic_block (else_bb
);
2745 remove_edge (find_edge (test_bb
, join_bb
));
2747 remove_edge (find_edge (then_bb
, join_bb
));
2748 redirect_edge_and_branch_force (single_succ_edge (test_bb
), join_bb
);
2749 delete_basic_block (then_bb
);
2752 if (can_merge_blocks_p (test_bb
, join_bb
))
2754 merge_blocks (test_bb
, join_bb
);
2758 num_updated_if_blocks
++;
2762 /* Check whether a block is suitable for conditional move conversion.
2763 Every insn must be a simple set of a register to a constant or a
2764 register. For each assignment, store the value in the pointer map
2765 VALS, keyed indexed by register pointer, then store the register
2766 pointer in REGS. COND is the condition we will test. */
2769 check_cond_move_block (basic_block bb
,
2770 hash_map
<rtx
, rtx
> *vals
,
2776 /* We can only handle simple jumps at the end of the basic block.
2777 It is almost impossible to update the CFG otherwise. */
2779 if (JUMP_P (insn
) && !onlyjump_p (insn
))
2782 FOR_BB_INSNS (bb
, insn
)
2786 if (!NONDEBUG_INSN_P (insn
) || JUMP_P (insn
))
2788 set
= single_set (insn
);
2792 dest
= SET_DEST (set
);
2793 src
= SET_SRC (set
);
2795 || (HARD_REGISTER_P (dest
)
2796 && targetm
.small_register_classes_for_mode_p (GET_MODE (dest
))))
2799 if (!CONSTANT_P (src
) && !register_operand (src
, VOIDmode
))
2802 if (side_effects_p (src
) || side_effects_p (dest
))
2805 if (may_trap_p (src
) || may_trap_p (dest
))
2808 /* Don't try to handle this if the source register was
2809 modified earlier in the block. */
2812 || (GET_CODE (src
) == SUBREG
&& REG_P (SUBREG_REG (src
))
2813 && vals
->get (SUBREG_REG (src
))))
2816 /* Don't try to handle this if the destination register was
2817 modified earlier in the block. */
2818 if (vals
->get (dest
))
2821 /* Don't try to handle this if the condition uses the
2822 destination register. */
2823 if (reg_overlap_mentioned_p (dest
, cond
))
2826 /* Don't try to handle this if the source register is modified
2827 later in the block. */
2828 if (!CONSTANT_P (src
)
2829 && modified_between_p (src
, insn
, NEXT_INSN (BB_END (bb
))))
2832 vals
->put (dest
, src
);
2834 regs
->safe_push (dest
);
2840 /* Given a basic block BB suitable for conditional move conversion,
2841 a condition COND, and pointer maps THEN_VALS and ELSE_VALS containing
2842 the register values depending on COND, emit the insns in the block as
2843 conditional moves. If ELSE_BLOCK is true, THEN_BB was already
2844 processed. The caller has started a sequence for the conversion.
2845 Return true if successful, false if something goes wrong. */
2848 cond_move_convert_if_block (struct noce_if_info
*if_infop
,
2849 basic_block bb
, rtx cond
,
2850 hash_map
<rtx
, rtx
> *then_vals
,
2851 hash_map
<rtx
, rtx
> *else_vals
,
2856 rtx cond_arg0
, cond_arg1
;
2858 code
= GET_CODE (cond
);
2859 cond_arg0
= XEXP (cond
, 0);
2860 cond_arg1
= XEXP (cond
, 1);
2862 FOR_BB_INSNS (bb
, insn
)
2864 rtx set
, target
, dest
, t
, e
;
2866 /* ??? Maybe emit conditional debug insn? */
2867 if (!NONDEBUG_INSN_P (insn
) || JUMP_P (insn
))
2869 set
= single_set (insn
);
2870 gcc_assert (set
&& REG_P (SET_DEST (set
)));
2872 dest
= SET_DEST (set
);
2874 rtx
*then_slot
= then_vals
->get (dest
);
2875 rtx
*else_slot
= else_vals
->get (dest
);
2876 t
= then_slot
? *then_slot
: NULL_RTX
;
2877 e
= else_slot
? *else_slot
: NULL_RTX
;
2881 /* If this register was set in the then block, we already
2882 handled this case there. */
2895 target
= noce_emit_cmove (if_infop
, dest
, code
, cond_arg0
, cond_arg1
,
2901 noce_emit_move_insn (dest
, target
);
2907 /* Given a simple IF-THEN-JOIN or IF-THEN-ELSE-JOIN block, attempt to convert
2908 it using only conditional moves. Return TRUE if we were successful at
2909 converting the block. */
2912 cond_move_process_if_block (struct noce_if_info
*if_info
)
2914 basic_block test_bb
= if_info
->test_bb
;
2915 basic_block then_bb
= if_info
->then_bb
;
2916 basic_block else_bb
= if_info
->else_bb
;
2917 basic_block join_bb
= if_info
->join_bb
;
2918 rtx_insn
*jump
= if_info
->jump
;
2919 rtx cond
= if_info
->cond
;
2920 rtx_insn
*seq
, *loc_insn
;
2923 vec
<rtx
> then_regs
= vNULL
;
2924 vec
<rtx
> else_regs
= vNULL
;
2926 int success_p
= FALSE
;
2928 /* Build a mapping for each block to the value used for each
2930 hash_map
<rtx
, rtx
> then_vals
;
2931 hash_map
<rtx
, rtx
> else_vals
;
2933 /* Make sure the blocks are suitable. */
2934 if (!check_cond_move_block (then_bb
, &then_vals
, &then_regs
, cond
)
2936 && !check_cond_move_block (else_bb
, &else_vals
, &else_regs
, cond
)))
2939 /* Make sure the blocks can be used together. If the same register
2940 is set in both blocks, and is not set to a constant in both
2941 cases, then both blocks must set it to the same register. We
2942 have already verified that if it is set to a register, that the
2943 source register does not change after the assignment. Also count
2944 the number of registers set in only one of the blocks. */
2946 FOR_EACH_VEC_ELT (then_regs
, i
, reg
)
2948 rtx
*then_slot
= then_vals
.get (reg
);
2949 rtx
*else_slot
= else_vals
.get (reg
);
2951 gcc_checking_assert (then_slot
);
2956 rtx then_val
= *then_slot
;
2957 rtx else_val
= *else_slot
;
2958 if (!CONSTANT_P (then_val
) && !CONSTANT_P (else_val
)
2959 && !rtx_equal_p (then_val
, else_val
))
2964 /* Finish off c for MAX_CONDITIONAL_EXECUTE. */
2965 FOR_EACH_VEC_ELT (else_regs
, i
, reg
)
2967 gcc_checking_assert (else_vals
.get (reg
));
2968 if (!then_vals
.get (reg
))
2972 /* Make sure it is reasonable to convert this block. What matters
2973 is the number of assignments currently made in only one of the
2974 branches, since if we convert we are going to always execute
2976 if (c
> MAX_CONDITIONAL_EXECUTE
)
2979 /* Try to emit the conditional moves. First do the then block,
2980 then do anything left in the else blocks. */
2982 if (!cond_move_convert_if_block (if_info
, then_bb
, cond
,
2983 &then_vals
, &else_vals
, false)
2985 && !cond_move_convert_if_block (if_info
, else_bb
, cond
,
2986 &then_vals
, &else_vals
, true)))
2991 seq
= end_ifcvt_sequence (if_info
);
2995 loc_insn
= first_active_insn (then_bb
);
2998 loc_insn
= first_active_insn (else_bb
);
2999 gcc_assert (loc_insn
);
3001 emit_insn_before_setloc (seq
, jump
, INSN_LOCATION (loc_insn
));
3005 delete_basic_block (else_bb
);
3009 remove_edge (find_edge (test_bb
, join_bb
));
3011 remove_edge (find_edge (then_bb
, join_bb
));
3012 redirect_edge_and_branch_force (single_succ_edge (test_bb
), join_bb
);
3013 delete_basic_block (then_bb
);
3016 if (can_merge_blocks_p (test_bb
, join_bb
))
3018 merge_blocks (test_bb
, join_bb
);
3022 num_updated_if_blocks
++;
3027 then_regs
.release ();
3028 else_regs
.release ();
3033 /* Determine if a given basic block heads a simple IF-THEN-JOIN or an
3034 IF-THEN-ELSE-JOIN block.
3036 If so, we'll try to convert the insns to not require the branch,
3037 using only transformations that do not require conditional execution.
3039 Return TRUE if we were successful at converting the block. */
3042 noce_find_if_block (basic_block test_bb
, edge then_edge
, edge else_edge
,
3045 basic_block then_bb
, else_bb
, join_bb
;
3046 bool then_else_reversed
= false;
3049 rtx_insn
*cond_earliest
;
3050 struct noce_if_info if_info
;
3052 /* We only ever should get here before reload. */
3053 gcc_assert (!reload_completed
);
3055 /* Recognize an IF-THEN-ELSE-JOIN block. */
3056 if (single_pred_p (then_edge
->dest
)
3057 && single_succ_p (then_edge
->dest
)
3058 && single_pred_p (else_edge
->dest
)
3059 && single_succ_p (else_edge
->dest
)
3060 && single_succ (then_edge
->dest
) == single_succ (else_edge
->dest
))
3062 then_bb
= then_edge
->dest
;
3063 else_bb
= else_edge
->dest
;
3064 join_bb
= single_succ (then_bb
);
3066 /* Recognize an IF-THEN-JOIN block. */
3067 else if (single_pred_p (then_edge
->dest
)
3068 && single_succ_p (then_edge
->dest
)
3069 && single_succ (then_edge
->dest
) == else_edge
->dest
)
3071 then_bb
= then_edge
->dest
;
3072 else_bb
= NULL_BLOCK
;
3073 join_bb
= else_edge
->dest
;
3075 /* Recognize an IF-ELSE-JOIN block. We can have those because the order
3076 of basic blocks in cfglayout mode does not matter, so the fallthrough
3077 edge can go to any basic block (and not just to bb->next_bb, like in
3079 else if (single_pred_p (else_edge
->dest
)
3080 && single_succ_p (else_edge
->dest
)
3081 && single_succ (else_edge
->dest
) == then_edge
->dest
)
3083 /* The noce transformations do not apply to IF-ELSE-JOIN blocks.
3084 To make this work, we have to invert the THEN and ELSE blocks
3085 and reverse the jump condition. */
3086 then_bb
= else_edge
->dest
;
3087 else_bb
= NULL_BLOCK
;
3088 join_bb
= single_succ (then_bb
);
3089 then_else_reversed
= true;
3092 /* Not a form we can handle. */
3095 /* The edges of the THEN and ELSE blocks cannot have complex edges. */
3096 if (single_succ_edge (then_bb
)->flags
& EDGE_COMPLEX
)
3099 && single_succ_edge (else_bb
)->flags
& EDGE_COMPLEX
)
3102 num_possible_if_blocks
++;
3107 "\nIF-THEN%s-JOIN block found, pass %d, test %d, then %d",
3108 (else_bb
) ? "-ELSE" : "",
3109 pass
, test_bb
->index
, then_bb
->index
);
3112 fprintf (dump_file
, ", else %d", else_bb
->index
);
3114 fprintf (dump_file
, ", join %d\n", join_bb
->index
);
3117 /* If the conditional jump is more than just a conditional
3118 jump, then we can not do if-conversion on this block. */
3119 jump
= BB_END (test_bb
);
3120 if (! onlyjump_p (jump
))
3123 /* If this is not a standard conditional jump, we can't parse it. */
3124 cond
= noce_get_condition (jump
, &cond_earliest
, then_else_reversed
);
3128 /* We must be comparing objects whose modes imply the size. */
3129 if (GET_MODE (XEXP (cond
, 0)) == BLKmode
)
3132 /* Initialize an IF_INFO struct to pass around. */
3133 memset (&if_info
, 0, sizeof if_info
);
3134 if_info
.test_bb
= test_bb
;
3135 if_info
.then_bb
= then_bb
;
3136 if_info
.else_bb
= else_bb
;
3137 if_info
.join_bb
= join_bb
;
3138 if_info
.cond
= cond
;
3139 if_info
.cond_earliest
= cond_earliest
;
3140 if_info
.jump
= jump
;
3141 if_info
.then_else_reversed
= then_else_reversed
;
3142 if_info
.branch_cost
= BRANCH_COST (optimize_bb_for_speed_p (test_bb
),
3143 predictable_edge_p (then_edge
));
3145 /* Do the real work. */
3147 if (noce_process_if_block (&if_info
))
3150 if (HAVE_conditional_move
3151 && cond_move_process_if_block (&if_info
))
3158 /* Merge the blocks and mark for local life update. */
3161 merge_if_block (struct ce_if_block
* ce_info
)
3163 basic_block test_bb
= ce_info
->test_bb
; /* last test block */
3164 basic_block then_bb
= ce_info
->then_bb
; /* THEN */
3165 basic_block else_bb
= ce_info
->else_bb
; /* ELSE or NULL */
3166 basic_block join_bb
= ce_info
->join_bb
; /* join block */
3167 basic_block combo_bb
;
3169 /* All block merging is done into the lower block numbers. */
3172 df_set_bb_dirty (test_bb
);
3174 /* Merge any basic blocks to handle && and || subtests. Each of
3175 the blocks are on the fallthru path from the predecessor block. */
3176 if (ce_info
->num_multiple_test_blocks
> 0)
3178 basic_block bb
= test_bb
;
3179 basic_block last_test_bb
= ce_info
->last_test_bb
;
3180 basic_block fallthru
= block_fallthru (bb
);
3185 fallthru
= block_fallthru (bb
);
3186 merge_blocks (combo_bb
, bb
);
3189 while (bb
!= last_test_bb
);
3192 /* Merge TEST block into THEN block. Normally the THEN block won't have a
3193 label, but it might if there were || tests. That label's count should be
3194 zero, and it normally should be removed. */
3198 /* If THEN_BB has no successors, then there's a BARRIER after it.
3199 If COMBO_BB has more than one successor (THEN_BB), then that BARRIER
3200 is no longer needed, and in fact it is incorrect to leave it in
3202 if (EDGE_COUNT (then_bb
->succs
) == 0
3203 && EDGE_COUNT (combo_bb
->succs
) > 1)
3205 rtx_insn
*end
= NEXT_INSN (BB_END (then_bb
));
3206 while (end
&& NOTE_P (end
) && !NOTE_INSN_BASIC_BLOCK_P (end
))
3207 end
= NEXT_INSN (end
);
3209 if (end
&& BARRIER_P (end
))
3212 merge_blocks (combo_bb
, then_bb
);
3216 /* The ELSE block, if it existed, had a label. That label count
3217 will almost always be zero, but odd things can happen when labels
3218 get their addresses taken. */
3221 /* If ELSE_BB has no successors, then there's a BARRIER after it.
3222 If COMBO_BB has more than one successor (ELSE_BB), then that BARRIER
3223 is no longer needed, and in fact it is incorrect to leave it in
3225 if (EDGE_COUNT (else_bb
->succs
) == 0
3226 && EDGE_COUNT (combo_bb
->succs
) > 1)
3228 rtx_insn
*end
= NEXT_INSN (BB_END (else_bb
));
3229 while (end
&& NOTE_P (end
) && !NOTE_INSN_BASIC_BLOCK_P (end
))
3230 end
= NEXT_INSN (end
);
3232 if (end
&& BARRIER_P (end
))
3235 merge_blocks (combo_bb
, else_bb
);
3239 /* If there was no join block reported, that means it was not adjacent
3240 to the others, and so we cannot merge them. */
3244 rtx_insn
*last
= BB_END (combo_bb
);
3246 /* The outgoing edge for the current COMBO block should already
3247 be correct. Verify this. */
3248 if (EDGE_COUNT (combo_bb
->succs
) == 0)
3249 gcc_assert (find_reg_note (last
, REG_NORETURN
, NULL
)
3250 || (NONJUMP_INSN_P (last
)
3251 && GET_CODE (PATTERN (last
)) == TRAP_IF
3252 && (TRAP_CONDITION (PATTERN (last
))
3253 == const_true_rtx
)));
3256 /* There should still be something at the end of the THEN or ELSE
3257 blocks taking us to our final destination. */
3258 gcc_assert (JUMP_P (last
)
3259 || (EDGE_SUCC (combo_bb
, 0)->dest
3260 == EXIT_BLOCK_PTR_FOR_FN (cfun
)
3262 && SIBLING_CALL_P (last
))
3263 || ((EDGE_SUCC (combo_bb
, 0)->flags
& EDGE_EH
)
3264 && can_throw_internal (last
)));
3267 /* The JOIN block may have had quite a number of other predecessors too.
3268 Since we've already merged the TEST, THEN and ELSE blocks, we should
3269 have only one remaining edge from our if-then-else diamond. If there
3270 is more than one remaining edge, it must come from elsewhere. There
3271 may be zero incoming edges if the THEN block didn't actually join
3272 back up (as with a call to a non-return function). */
3273 else if (EDGE_COUNT (join_bb
->preds
) < 2
3274 && join_bb
!= EXIT_BLOCK_PTR_FOR_FN (cfun
))
3276 /* We can merge the JOIN cleanly and update the dataflow try
3277 again on this pass.*/
3278 merge_blocks (combo_bb
, join_bb
);
3283 /* We cannot merge the JOIN. */
3285 /* The outgoing edge for the current COMBO block should already
3286 be correct. Verify this. */
3287 gcc_assert (single_succ_p (combo_bb
)
3288 && single_succ (combo_bb
) == join_bb
);
3290 /* Remove the jump and cruft from the end of the COMBO block. */
3291 if (join_bb
!= EXIT_BLOCK_PTR_FOR_FN (cfun
))
3292 tidy_fallthru_edge (single_succ_edge (combo_bb
));
3295 num_updated_if_blocks
++;
3298 /* Find a block ending in a simple IF condition and try to transform it
3299 in some way. When converting a multi-block condition, put the new code
3300 in the first such block and delete the rest. Return a pointer to this
3301 first block if some transformation was done. Return NULL otherwise. */
3304 find_if_header (basic_block test_bb
, int pass
)
3306 ce_if_block ce_info
;
3310 /* The kind of block we're looking for has exactly two successors. */
3311 if (EDGE_COUNT (test_bb
->succs
) != 2)
3314 then_edge
= EDGE_SUCC (test_bb
, 0);
3315 else_edge
= EDGE_SUCC (test_bb
, 1);
3317 if (df_get_bb_dirty (then_edge
->dest
))
3319 if (df_get_bb_dirty (else_edge
->dest
))
3322 /* Neither edge should be abnormal. */
3323 if ((then_edge
->flags
& EDGE_COMPLEX
)
3324 || (else_edge
->flags
& EDGE_COMPLEX
))
3327 /* Nor exit the loop. */
3328 if ((then_edge
->flags
& EDGE_LOOP_EXIT
)
3329 || (else_edge
->flags
& EDGE_LOOP_EXIT
))
3332 /* The THEN edge is canonically the one that falls through. */
3333 if (then_edge
->flags
& EDGE_FALLTHRU
)
3335 else if (else_edge
->flags
& EDGE_FALLTHRU
)
3338 else_edge
= then_edge
;
3342 /* Otherwise this must be a multiway branch of some sort. */
3345 memset (&ce_info
, 0, sizeof (ce_info
));
3346 ce_info
.test_bb
= test_bb
;
3347 ce_info
.then_bb
= then_edge
->dest
;
3348 ce_info
.else_bb
= else_edge
->dest
;
3349 ce_info
.pass
= pass
;
3351 #ifdef IFCVT_MACHDEP_INIT
3352 IFCVT_MACHDEP_INIT (&ce_info
);
3355 if (!reload_completed
3356 && noce_find_if_block (test_bb
, then_edge
, else_edge
, pass
))
3359 if (reload_completed
3360 && targetm
.have_conditional_execution ()
3361 && cond_exec_find_if_block (&ce_info
))
3365 && optab_handler (ctrap_optab
, word_mode
) != CODE_FOR_nothing
3366 && find_cond_trap (test_bb
, then_edge
, else_edge
))
3369 if (dom_info_state (CDI_POST_DOMINATORS
) >= DOM_NO_FAST_QUERY
3370 && (reload_completed
|| !targetm
.have_conditional_execution ()))
3372 if (find_if_case_1 (test_bb
, then_edge
, else_edge
))
3374 if (find_if_case_2 (test_bb
, then_edge
, else_edge
))
3382 fprintf (dump_file
, "Conversion succeeded on pass %d.\n", pass
);
3383 /* Set this so we continue looking. */
3384 cond_exec_changed_p
= TRUE
;
3385 return ce_info
.test_bb
;
3388 /* Return true if a block has two edges, one of which falls through to the next
3389 block, and the other jumps to a specific block, so that we can tell if the
3390 block is part of an && test or an || test. Returns either -1 or the number
3391 of non-note, non-jump, non-USE/CLOBBER insns in the block. */
3394 block_jumps_and_fallthru_p (basic_block cur_bb
, basic_block target_bb
)
3397 int fallthru_p
= FALSE
;
3404 if (!cur_bb
|| !target_bb
)
3407 /* If no edges, obviously it doesn't jump or fallthru. */
3408 if (EDGE_COUNT (cur_bb
->succs
) == 0)
3411 FOR_EACH_EDGE (cur_edge
, ei
, cur_bb
->succs
)
3413 if (cur_edge
->flags
& EDGE_COMPLEX
)
3414 /* Anything complex isn't what we want. */
3417 else if (cur_edge
->flags
& EDGE_FALLTHRU
)
3420 else if (cur_edge
->dest
== target_bb
)
3427 if ((jump_p
& fallthru_p
) == 0)
3430 /* Don't allow calls in the block, since this is used to group && and ||
3431 together for conditional execution support. ??? we should support
3432 conditional execution support across calls for IA-64 some day, but
3433 for now it makes the code simpler. */
3434 end
= BB_END (cur_bb
);
3435 insn
= BB_HEAD (cur_bb
);
3437 while (insn
!= NULL_RTX
)
3444 && !DEBUG_INSN_P (insn
)
3445 && GET_CODE (PATTERN (insn
)) != USE
3446 && GET_CODE (PATTERN (insn
)) != CLOBBER
)
3452 insn
= NEXT_INSN (insn
);
3458 /* Determine if a given basic block heads a simple IF-THEN or IF-THEN-ELSE
3459 block. If so, we'll try to convert the insns to not require the branch.
3460 Return TRUE if we were successful at converting the block. */
3463 cond_exec_find_if_block (struct ce_if_block
* ce_info
)
3465 basic_block test_bb
= ce_info
->test_bb
;
3466 basic_block then_bb
= ce_info
->then_bb
;
3467 basic_block else_bb
= ce_info
->else_bb
;
3468 basic_block join_bb
= NULL_BLOCK
;
3473 ce_info
->last_test_bb
= test_bb
;
3475 /* We only ever should get here after reload,
3476 and if we have conditional execution. */
3477 gcc_assert (reload_completed
&& targetm
.have_conditional_execution ());
3479 /* Discover if any fall through predecessors of the current test basic block
3480 were && tests (which jump to the else block) or || tests (which jump to
3482 if (single_pred_p (test_bb
)
3483 && single_pred_edge (test_bb
)->flags
== EDGE_FALLTHRU
)
3485 basic_block bb
= single_pred (test_bb
);
3486 basic_block target_bb
;
3487 int max_insns
= MAX_CONDITIONAL_EXECUTE
;
3490 /* Determine if the preceding block is an && or || block. */
3491 if ((n_insns
= block_jumps_and_fallthru_p (bb
, else_bb
)) >= 0)
3493 ce_info
->and_and_p
= TRUE
;
3494 target_bb
= else_bb
;
3496 else if ((n_insns
= block_jumps_and_fallthru_p (bb
, then_bb
)) >= 0)
3498 ce_info
->and_and_p
= FALSE
;
3499 target_bb
= then_bb
;
3502 target_bb
= NULL_BLOCK
;
3504 if (target_bb
&& n_insns
<= max_insns
)
3506 int total_insns
= 0;
3509 ce_info
->last_test_bb
= test_bb
;
3511 /* Found at least one && or || block, look for more. */
3514 ce_info
->test_bb
= test_bb
= bb
;
3515 total_insns
+= n_insns
;
3518 if (!single_pred_p (bb
))
3521 bb
= single_pred (bb
);
3522 n_insns
= block_jumps_and_fallthru_p (bb
, target_bb
);
3524 while (n_insns
>= 0 && (total_insns
+ n_insns
) <= max_insns
);
3526 ce_info
->num_multiple_test_blocks
= blocks
;
3527 ce_info
->num_multiple_test_insns
= total_insns
;
3529 if (ce_info
->and_and_p
)
3530 ce_info
->num_and_and_blocks
= blocks
;
3532 ce_info
->num_or_or_blocks
= blocks
;
3536 /* The THEN block of an IF-THEN combo must have exactly one predecessor,
3537 other than any || blocks which jump to the THEN block. */
3538 if ((EDGE_COUNT (then_bb
->preds
) - ce_info
->num_or_or_blocks
) != 1)
3541 /* The edges of the THEN and ELSE blocks cannot have complex edges. */
3542 FOR_EACH_EDGE (cur_edge
, ei
, then_bb
->preds
)
3544 if (cur_edge
->flags
& EDGE_COMPLEX
)
3548 FOR_EACH_EDGE (cur_edge
, ei
, else_bb
->preds
)
3550 if (cur_edge
->flags
& EDGE_COMPLEX
)
3554 /* The THEN block of an IF-THEN combo must have zero or one successors. */
3555 if (EDGE_COUNT (then_bb
->succs
) > 0
3556 && (!single_succ_p (then_bb
)
3557 || (single_succ_edge (then_bb
)->flags
& EDGE_COMPLEX
)
3558 || (epilogue_completed
3559 && tablejump_p (BB_END (then_bb
), NULL
, NULL
))))
3562 /* If the THEN block has no successors, conditional execution can still
3563 make a conditional call. Don't do this unless the ELSE block has
3564 only one incoming edge -- the CFG manipulation is too ugly otherwise.
3565 Check for the last insn of the THEN block being an indirect jump, which
3566 is listed as not having any successors, but confuses the rest of the CE
3567 code processing. ??? we should fix this in the future. */
3568 if (EDGE_COUNT (then_bb
->succs
) == 0)
3570 if (single_pred_p (else_bb
) && else_bb
!= EXIT_BLOCK_PTR_FOR_FN (cfun
))
3572 rtx_insn
*last_insn
= BB_END (then_bb
);
3575 && NOTE_P (last_insn
)
3576 && last_insn
!= BB_HEAD (then_bb
))
3577 last_insn
= PREV_INSN (last_insn
);
3580 && JUMP_P (last_insn
)
3581 && ! simplejump_p (last_insn
))
3585 else_bb
= NULL_BLOCK
;
3591 /* If the THEN block's successor is the other edge out of the TEST block,
3592 then we have an IF-THEN combo without an ELSE. */
3593 else if (single_succ (then_bb
) == else_bb
)
3596 else_bb
= NULL_BLOCK
;
3599 /* If the THEN and ELSE block meet in a subsequent block, and the ELSE
3600 has exactly one predecessor and one successor, and the outgoing edge
3601 is not complex, then we have an IF-THEN-ELSE combo. */
3602 else if (single_succ_p (else_bb
)
3603 && single_succ (then_bb
) == single_succ (else_bb
)
3604 && single_pred_p (else_bb
)
3605 && !(single_succ_edge (else_bb
)->flags
& EDGE_COMPLEX
)
3606 && !(epilogue_completed
3607 && tablejump_p (BB_END (else_bb
), NULL
, NULL
)))
3608 join_bb
= single_succ (else_bb
);
3610 /* Otherwise it is not an IF-THEN or IF-THEN-ELSE combination. */
3614 num_possible_if_blocks
++;
3619 "\nIF-THEN%s block found, pass %d, start block %d "
3620 "[insn %d], then %d [%d]",
3621 (else_bb
) ? "-ELSE" : "",
3624 BB_HEAD (test_bb
) ? (int)INSN_UID (BB_HEAD (test_bb
)) : -1,
3626 BB_HEAD (then_bb
) ? (int)INSN_UID (BB_HEAD (then_bb
)) : -1);
3629 fprintf (dump_file
, ", else %d [%d]",
3631 BB_HEAD (else_bb
) ? (int)INSN_UID (BB_HEAD (else_bb
)) : -1);
3633 fprintf (dump_file
, ", join %d [%d]",
3635 BB_HEAD (join_bb
) ? (int)INSN_UID (BB_HEAD (join_bb
)) : -1);
3637 if (ce_info
->num_multiple_test_blocks
> 0)
3638 fprintf (dump_file
, ", %d %s block%s last test %d [%d]",
3639 ce_info
->num_multiple_test_blocks
,
3640 (ce_info
->and_and_p
) ? "&&" : "||",
3641 (ce_info
->num_multiple_test_blocks
== 1) ? "" : "s",
3642 ce_info
->last_test_bb
->index
,
3643 ((BB_HEAD (ce_info
->last_test_bb
))
3644 ? (int)INSN_UID (BB_HEAD (ce_info
->last_test_bb
))
3647 fputc ('\n', dump_file
);
3650 /* Make sure IF, THEN, and ELSE, blocks are adjacent. Actually, we get the
3651 first condition for free, since we've already asserted that there's a
3652 fallthru edge from IF to THEN. Likewise for the && and || blocks, since
3653 we checked the FALLTHRU flag, those are already adjacent to the last IF
3655 /* ??? As an enhancement, move the ELSE block. Have to deal with
3656 BLOCK notes, if by no other means than backing out the merge if they
3657 exist. Sticky enough I don't want to think about it now. */
3659 if (else_bb
&& (next
= next
->next_bb
) != else_bb
)
3661 if ((next
= next
->next_bb
) != join_bb
3662 && join_bb
!= EXIT_BLOCK_PTR_FOR_FN (cfun
))
3670 /* Do the real work. */
3672 ce_info
->else_bb
= else_bb
;
3673 ce_info
->join_bb
= join_bb
;
3675 /* If we have && and || tests, try to first handle combining the && and ||
3676 tests into the conditional code, and if that fails, go back and handle
3677 it without the && and ||, which at present handles the && case if there
3678 was no ELSE block. */
3679 if (cond_exec_process_if_block (ce_info
, TRUE
))
3682 if (ce_info
->num_multiple_test_blocks
)
3686 if (cond_exec_process_if_block (ce_info
, FALSE
))
3693 /* Convert a branch over a trap, or a branch
3694 to a trap, into a conditional trap. */
3697 find_cond_trap (basic_block test_bb
, edge then_edge
, edge else_edge
)
3699 basic_block then_bb
= then_edge
->dest
;
3700 basic_block else_bb
= else_edge
->dest
;
3701 basic_block other_bb
, trap_bb
;
3702 rtx_insn
*trap
, *jump
;
3704 rtx_insn
*cond_earliest
;
3707 /* Locate the block with the trap instruction. */
3708 /* ??? While we look for no successors, we really ought to allow
3709 EH successors. Need to fix merge_if_block for that to work. */
3710 if ((trap
= block_has_only_trap (then_bb
)) != NULL
)
3711 trap_bb
= then_bb
, other_bb
= else_bb
;
3712 else if ((trap
= block_has_only_trap (else_bb
)) != NULL
)
3713 trap_bb
= else_bb
, other_bb
= then_bb
;
3719 fprintf (dump_file
, "\nTRAP-IF block found, start %d, trap %d\n",
3720 test_bb
->index
, trap_bb
->index
);
3723 /* If this is not a standard conditional jump, we can't parse it. */
3724 jump
= BB_END (test_bb
);
3725 cond
= noce_get_condition (jump
, &cond_earliest
, false);
3729 /* If the conditional jump is more than just a conditional jump, then
3730 we can not do if-conversion on this block. */
3731 if (! onlyjump_p (jump
))
3734 /* We must be comparing objects whose modes imply the size. */
3735 if (GET_MODE (XEXP (cond
, 0)) == BLKmode
)
3738 /* Reverse the comparison code, if necessary. */
3739 code
= GET_CODE (cond
);
3740 if (then_bb
== trap_bb
)
3742 code
= reversed_comparison_code (cond
, jump
);
3743 if (code
== UNKNOWN
)
3747 /* Attempt to generate the conditional trap. */
3748 seq
= gen_cond_trap (code
, copy_rtx (XEXP (cond
, 0)),
3749 copy_rtx (XEXP (cond
, 1)),
3750 TRAP_CODE (PATTERN (trap
)));
3754 /* Emit the new insns before cond_earliest. */
3755 emit_insn_before_setloc (seq
, cond_earliest
, INSN_LOCATION (trap
));
3757 /* Delete the trap block if possible. */
3758 remove_edge (trap_bb
== then_bb
? then_edge
: else_edge
);
3759 df_set_bb_dirty (test_bb
);
3760 df_set_bb_dirty (then_bb
);
3761 df_set_bb_dirty (else_bb
);
3763 if (EDGE_COUNT (trap_bb
->preds
) == 0)
3765 delete_basic_block (trap_bb
);
3769 /* Wire together the blocks again. */
3770 if (current_ir_type () == IR_RTL_CFGLAYOUT
)
3771 single_succ_edge (test_bb
)->flags
|= EDGE_FALLTHRU
;
3772 else if (trap_bb
== then_bb
)
3777 lab
= JUMP_LABEL (jump
);
3778 newjump
= emit_jump_insn_after (gen_jump (lab
), jump
);
3779 LABEL_NUSES (lab
) += 1;
3780 JUMP_LABEL (newjump
) = lab
;
3781 emit_barrier_after (newjump
);
3785 if (can_merge_blocks_p (test_bb
, other_bb
))
3787 merge_blocks (test_bb
, other_bb
);
3791 num_updated_if_blocks
++;
3795 /* Subroutine of find_cond_trap: if BB contains only a trap insn,
3799 block_has_only_trap (basic_block bb
)
3803 /* We're not the exit block. */
3804 if (bb
== EXIT_BLOCK_PTR_FOR_FN (cfun
))
3807 /* The block must have no successors. */
3808 if (EDGE_COUNT (bb
->succs
) > 0)
3811 /* The only instruction in the THEN block must be the trap. */
3812 trap
= first_active_insn (bb
);
3813 if (! (trap
== BB_END (bb
)
3814 && GET_CODE (PATTERN (trap
)) == TRAP_IF
3815 && TRAP_CONDITION (PATTERN (trap
)) == const_true_rtx
))
3821 /* Look for IF-THEN-ELSE cases in which one of THEN or ELSE is
3822 transformable, but not necessarily the other. There need be no
3825 Return TRUE if we were successful at converting the block.
3827 Cases we'd like to look at:
3830 if (test) goto over; // x not live
3838 if (! test) goto label;
3841 if (test) goto E; // x not live
3855 (3) // This one's really only interesting for targets that can do
3856 // multiway branching, e.g. IA-64 BBB bundles. For other targets
3857 // it results in multiple branches on a cache line, which often
3858 // does not sit well with predictors.
3860 if (test1) goto E; // predicted not taken
3876 (A) Don't do (2) if the branch is predicted against the block we're
3877 eliminating. Do it anyway if we can eliminate a branch; this requires
3878 that the sole successor of the eliminated block postdominate the other
3881 (B) With CE, on (3) we can steal from both sides of the if, creating
3890 Again, this is most useful if J postdominates.
3892 (C) CE substitutes for helpful life information.
3894 (D) These heuristics need a lot of work. */
3896 /* Tests for case 1 above. */
3899 find_if_case_1 (basic_block test_bb
, edge then_edge
, edge else_edge
)
3901 basic_block then_bb
= then_edge
->dest
;
3902 basic_block else_bb
= else_edge
->dest
;
3904 int then_bb_index
, then_prob
;
3905 rtx else_target
= NULL_RTX
;
3907 /* If we are partitioning hot/cold basic blocks, we don't want to
3908 mess up unconditional or indirect jumps that cross between hot
3911 Basic block partitioning may result in some jumps that appear to
3912 be optimizable (or blocks that appear to be mergeable), but which really
3913 must be left untouched (they are required to make it safely across
3914 partition boundaries). See the comments at the top of
3915 bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */
3917 if ((BB_END (then_bb
)
3918 && JUMP_P (BB_END (then_bb
))
3919 && CROSSING_JUMP_P (BB_END (then_bb
)))
3920 || (BB_END (test_bb
)
3921 && JUMP_P (BB_END (test_bb
))
3922 && CROSSING_JUMP_P (BB_END (test_bb
)))
3923 || (BB_END (else_bb
)
3924 && JUMP_P (BB_END (else_bb
))
3925 && CROSSING_JUMP_P (BB_END (else_bb
))))
3928 /* THEN has one successor. */
3929 if (!single_succ_p (then_bb
))
3932 /* THEN does not fall through, but is not strange either. */
3933 if (single_succ_edge (then_bb
)->flags
& (EDGE_COMPLEX
| EDGE_FALLTHRU
))
3936 /* THEN has one predecessor. */
3937 if (!single_pred_p (then_bb
))
3940 /* THEN must do something. */
3941 if (forwarder_block_p (then_bb
))
3944 num_possible_if_blocks
++;
3947 "\nIF-CASE-1 found, start %d, then %d\n",
3948 test_bb
->index
, then_bb
->index
);
3950 if (then_edge
->probability
)
3951 then_prob
= REG_BR_PROB_BASE
- then_edge
->probability
;
3953 then_prob
= REG_BR_PROB_BASE
/ 2;
3955 /* We're speculating from the THEN path, we want to make sure the cost
3956 of speculation is within reason. */
3957 if (! cheap_bb_rtx_cost_p (then_bb
, then_prob
,
3958 COSTS_N_INSNS (BRANCH_COST (optimize_bb_for_speed_p (then_edge
->src
),
3959 predictable_edge_p (then_edge
)))))
3962 if (else_bb
== EXIT_BLOCK_PTR_FOR_FN (cfun
))
3964 rtx_insn
*jump
= BB_END (else_edge
->src
);
3965 gcc_assert (JUMP_P (jump
));
3966 else_target
= JUMP_LABEL (jump
);
3969 /* Registers set are dead, or are predicable. */
3970 if (! dead_or_predicable (test_bb
, then_bb
, else_bb
,
3971 single_succ_edge (then_bb
), 1))
3974 /* Conversion went ok, including moving the insns and fixing up the
3975 jump. Adjust the CFG to match. */
3977 /* We can avoid creating a new basic block if then_bb is immediately
3978 followed by else_bb, i.e. deleting then_bb allows test_bb to fall
3979 through to else_bb. */
3981 if (then_bb
->next_bb
== else_bb
3982 && then_bb
->prev_bb
== test_bb
3983 && else_bb
!= EXIT_BLOCK_PTR_FOR_FN (cfun
))
3985 redirect_edge_succ (FALLTHRU_EDGE (test_bb
), else_bb
);
3988 else if (else_bb
== EXIT_BLOCK_PTR_FOR_FN (cfun
))
3989 new_bb
= force_nonfallthru_and_redirect (FALLTHRU_EDGE (test_bb
),
3990 else_bb
, else_target
);
3992 new_bb
= redirect_edge_and_branch_force (FALLTHRU_EDGE (test_bb
),
3995 df_set_bb_dirty (test_bb
);
3996 df_set_bb_dirty (else_bb
);
3998 then_bb_index
= then_bb
->index
;
3999 delete_basic_block (then_bb
);
4001 /* Make rest of code believe that the newly created block is the THEN_BB
4002 block we removed. */
4005 df_bb_replace (then_bb_index
, new_bb
);
4006 /* This should have been done above via force_nonfallthru_and_redirect
4007 (possibly called from redirect_edge_and_branch_force). */
4008 gcc_checking_assert (BB_PARTITION (new_bb
) == BB_PARTITION (test_bb
));
4012 num_updated_if_blocks
++;
4017 /* Test for case 2 above. */
4020 find_if_case_2 (basic_block test_bb
, edge then_edge
, edge else_edge
)
4022 basic_block then_bb
= then_edge
->dest
;
4023 basic_block else_bb
= else_edge
->dest
;
4025 int then_prob
, else_prob
;
4027 /* We do not want to speculate (empty) loop latches. */
4029 && else_bb
->loop_father
->latch
== else_bb
)
4032 /* If we are partitioning hot/cold basic blocks, we don't want to
4033 mess up unconditional or indirect jumps that cross between hot
4036 Basic block partitioning may result in some jumps that appear to
4037 be optimizable (or blocks that appear to be mergeable), but which really
4038 must be left untouched (they are required to make it safely across
4039 partition boundaries). See the comments at the top of
4040 bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */
4042 if ((BB_END (then_bb
)
4043 && JUMP_P (BB_END (then_bb
))
4044 && CROSSING_JUMP_P (BB_END (then_bb
)))
4045 || (BB_END (test_bb
)
4046 && JUMP_P (BB_END (test_bb
))
4047 && CROSSING_JUMP_P (BB_END (test_bb
)))
4048 || (BB_END (else_bb
)
4049 && JUMP_P (BB_END (else_bb
))
4050 && CROSSING_JUMP_P (BB_END (else_bb
))))
4053 /* ELSE has one successor. */
4054 if (!single_succ_p (else_bb
))
4057 else_succ
= single_succ_edge (else_bb
);
4059 /* ELSE outgoing edge is not complex. */
4060 if (else_succ
->flags
& EDGE_COMPLEX
)
4063 /* ELSE has one predecessor. */
4064 if (!single_pred_p (else_bb
))
4067 /* THEN is not EXIT. */
4068 if (then_bb
->index
< NUM_FIXED_BLOCKS
)
4071 if (else_edge
->probability
)
4073 else_prob
= else_edge
->probability
;
4074 then_prob
= REG_BR_PROB_BASE
- else_prob
;
4078 else_prob
= REG_BR_PROB_BASE
/ 2;
4079 then_prob
= REG_BR_PROB_BASE
/ 2;
4082 /* ELSE is predicted or SUCC(ELSE) postdominates THEN. */
4083 if (else_prob
> then_prob
)
4085 else if (else_succ
->dest
->index
< NUM_FIXED_BLOCKS
4086 || dominated_by_p (CDI_POST_DOMINATORS
, then_bb
,
4092 num_possible_if_blocks
++;
4095 "\nIF-CASE-2 found, start %d, else %d\n",
4096 test_bb
->index
, else_bb
->index
);
4098 /* We're speculating from the ELSE path, we want to make sure the cost
4099 of speculation is within reason. */
4100 if (! cheap_bb_rtx_cost_p (else_bb
, else_prob
,
4101 COSTS_N_INSNS (BRANCH_COST (optimize_bb_for_speed_p (else_edge
->src
),
4102 predictable_edge_p (else_edge
)))))
4105 /* Registers set are dead, or are predicable. */
4106 if (! dead_or_predicable (test_bb
, else_bb
, then_bb
, else_succ
, 0))
4109 /* Conversion went ok, including moving the insns and fixing up the
4110 jump. Adjust the CFG to match. */
4112 df_set_bb_dirty (test_bb
);
4113 df_set_bb_dirty (then_bb
);
4114 delete_basic_block (else_bb
);
4117 num_updated_if_blocks
++;
4119 /* ??? We may now fallthru from one of THEN's successors into a join
4120 block. Rerun cleanup_cfg? Examine things manually? Wait? */
4125 /* Used by the code above to perform the actual rtl transformations.
4126 Return TRUE if successful.
4128 TEST_BB is the block containing the conditional branch. MERGE_BB
4129 is the block containing the code to manipulate. DEST_EDGE is an
4130 edge representing a jump to the join block; after the conversion,
4131 TEST_BB should be branching to its destination.
4132 REVERSEP is true if the sense of the branch should be reversed. */
4135 dead_or_predicable (basic_block test_bb
, basic_block merge_bb
,
4136 basic_block other_bb
, edge dest_edge
, int reversep
)
4138 basic_block new_dest
= dest_edge
->dest
;
4139 rtx_insn
*head
, *end
, *jump
;
4140 rtx_insn
*earliest
= NULL
;
4142 bitmap merge_set
= NULL
;
4143 /* Number of pending changes. */
4144 int n_validated_changes
= 0;
4145 rtx new_dest_label
= NULL_RTX
;
4147 jump
= BB_END (test_bb
);
4149 /* Find the extent of the real code in the merge block. */
4150 head
= BB_HEAD (merge_bb
);
4151 end
= BB_END (merge_bb
);
4153 while (DEBUG_INSN_P (end
) && end
!= head
)
4154 end
= PREV_INSN (end
);
4156 /* If merge_bb ends with a tablejump, predicating/moving insn's
4157 into test_bb and then deleting merge_bb will result in the jumptable
4158 that follows merge_bb being removed along with merge_bb and then we
4159 get an unresolved reference to the jumptable. */
4160 if (tablejump_p (end
, NULL
, NULL
))
4164 head
= NEXT_INSN (head
);
4165 while (DEBUG_INSN_P (head
) && head
!= end
)
4166 head
= NEXT_INSN (head
);
4174 head
= NEXT_INSN (head
);
4175 while (DEBUG_INSN_P (head
) && head
!= end
)
4176 head
= NEXT_INSN (head
);
4181 if (!onlyjump_p (end
))
4188 end
= PREV_INSN (end
);
4189 while (DEBUG_INSN_P (end
) && end
!= head
)
4190 end
= PREV_INSN (end
);
4193 /* Don't move frame-related insn across the conditional branch. This
4194 can lead to one of the paths of the branch having wrong unwind info. */
4195 if (epilogue_completed
)
4197 rtx_insn
*insn
= head
;
4200 if (INSN_P (insn
) && RTX_FRAME_RELATED_P (insn
))
4204 insn
= NEXT_INSN (insn
);
4208 /* Disable handling dead code by conditional execution if the machine needs
4209 to do anything funny with the tests, etc. */
4210 #ifndef IFCVT_MODIFY_TESTS
4211 if (targetm
.have_conditional_execution ())
4213 /* In the conditional execution case, we have things easy. We know
4214 the condition is reversible. We don't have to check life info
4215 because we're going to conditionally execute the code anyway.
4216 All that's left is making sure the insns involved can actually
4221 cond
= cond_exec_get_condition (jump
);
4225 rtx note
= find_reg_note (jump
, REG_BR_PROB
, NULL_RTX
);
4226 int prob_val
= (note
? XINT (note
, 0) : -1);
4230 enum rtx_code rev
= reversed_comparison_code (cond
, jump
);
4233 cond
= gen_rtx_fmt_ee (rev
, GET_MODE (cond
), XEXP (cond
, 0),
4236 prob_val
= REG_BR_PROB_BASE
- prob_val
;
4239 if (cond_exec_process_insns (NULL
, head
, end
, cond
, prob_val
, 0)
4240 && verify_changes (0))
4241 n_validated_changes
= num_validated_changes ();
4249 /* If we allocated new pseudos (e.g. in the conditional move
4250 expander called from noce_emit_cmove), we must resize the
4252 if (max_regno
< max_reg_num ())
4253 max_regno
= max_reg_num ();
4255 /* Try the NCE path if the CE path did not result in any changes. */
4256 if (n_validated_changes
== 0)
4263 /* In the non-conditional execution case, we have to verify that there
4264 are no trapping operations, no calls, no references to memory, and
4265 that any registers modified are dead at the branch site. */
4267 if (!any_condjump_p (jump
))
4270 /* Find the extent of the conditional. */
4271 cond
= noce_get_condition (jump
, &earliest
, false);
4275 live
= BITMAP_ALLOC (®_obstack
);
4276 simulate_backwards_to_point (merge_bb
, live
, end
);
4277 success
= can_move_insns_across (head
, end
, earliest
, jump
,
4279 df_get_live_in (other_bb
), NULL
);
4284 /* Collect the set of registers set in MERGE_BB. */
4285 merge_set
= BITMAP_ALLOC (®_obstack
);
4287 FOR_BB_INSNS (merge_bb
, insn
)
4288 if (NONDEBUG_INSN_P (insn
))
4289 df_simulate_find_defs (insn
, merge_set
);
4291 #ifdef HAVE_simple_return
4292 /* If shrink-wrapping, disable this optimization when test_bb is
4293 the first basic block and merge_bb exits. The idea is to not
4294 move code setting up a return register as that may clobber a
4295 register used to pass function parameters, which then must be
4296 saved in caller-saved regs. A caller-saved reg requires the
4297 prologue, killing a shrink-wrap opportunity. */
4298 if ((flag_shrink_wrap
&& HAVE_simple_return
&& !epilogue_completed
)
4299 && ENTRY_BLOCK_PTR_FOR_FN (cfun
)->next_bb
== test_bb
4300 && single_succ_p (new_dest
)
4301 && single_succ (new_dest
) == EXIT_BLOCK_PTR_FOR_FN (cfun
)
4302 && bitmap_intersect_p (df_get_live_in (new_dest
), merge_set
))
4307 return_regs
= BITMAP_ALLOC (®_obstack
);
4309 /* Start off with the intersection of regs used to pass
4310 params and regs used to return values. */
4311 for (i
= 0; i
< FIRST_PSEUDO_REGISTER
; i
++)
4312 if (FUNCTION_ARG_REGNO_P (i
)
4313 && targetm
.calls
.function_value_regno_p (i
))
4314 bitmap_set_bit (return_regs
, INCOMING_REGNO (i
));
4316 bitmap_and_into (return_regs
,
4317 df_get_live_out (ENTRY_BLOCK_PTR_FOR_FN (cfun
)));
4318 bitmap_and_into (return_regs
,
4319 df_get_live_in (EXIT_BLOCK_PTR_FOR_FN (cfun
)));
4320 if (!bitmap_empty_p (return_regs
))
4322 FOR_BB_INSNS_REVERSE (new_dest
, insn
)
4323 if (NONDEBUG_INSN_P (insn
))
4327 /* If this insn sets any reg in return_regs, add all
4328 reg uses to the set of regs we're interested in. */
4329 FOR_EACH_INSN_DEF (def
, insn
)
4330 if (bitmap_bit_p (return_regs
, DF_REF_REGNO (def
)))
4332 df_simulate_uses (insn
, return_regs
);
4336 if (bitmap_intersect_p (merge_set
, return_regs
))
4338 BITMAP_FREE (return_regs
);
4339 BITMAP_FREE (merge_set
);
4343 BITMAP_FREE (return_regs
);
4349 /* We don't want to use normal invert_jump or redirect_jump because
4350 we don't want to delete_insn called. Also, we want to do our own
4351 change group management. */
4353 old_dest
= JUMP_LABEL (jump
);
4354 if (other_bb
!= new_dest
)
4356 if (JUMP_P (BB_END (dest_edge
->src
)))
4357 new_dest_label
= JUMP_LABEL (BB_END (dest_edge
->src
));
4358 else if (new_dest
== EXIT_BLOCK_PTR_FOR_FN (cfun
))
4359 new_dest_label
= ret_rtx
;
4361 new_dest_label
= block_label (new_dest
);
4364 ? ! invert_jump_1 (jump
, new_dest_label
)
4365 : ! redirect_jump_1 (jump
, new_dest_label
))
4369 if (verify_changes (n_validated_changes
))
4370 confirm_change_group ();
4374 if (other_bb
!= new_dest
)
4376 redirect_jump_2 (jump
, old_dest
, new_dest_label
, 0, reversep
);
4378 redirect_edge_succ (BRANCH_EDGE (test_bb
), new_dest
);
4381 gcov_type count
, probability
;
4382 count
= BRANCH_EDGE (test_bb
)->count
;
4383 BRANCH_EDGE (test_bb
)->count
= FALLTHRU_EDGE (test_bb
)->count
;
4384 FALLTHRU_EDGE (test_bb
)->count
= count
;
4385 probability
= BRANCH_EDGE (test_bb
)->probability
;
4386 BRANCH_EDGE (test_bb
)->probability
4387 = FALLTHRU_EDGE (test_bb
)->probability
;
4388 FALLTHRU_EDGE (test_bb
)->probability
= probability
;
4389 update_br_prob_note (test_bb
);
4393 /* Move the insns out of MERGE_BB to before the branch. */
4398 if (end
== BB_END (merge_bb
))
4399 BB_END (merge_bb
) = PREV_INSN (head
);
4401 /* PR 21767: when moving insns above a conditional branch, the REG_EQUAL
4402 notes being moved might become invalid. */
4408 if (! INSN_P (insn
))
4410 note
= find_reg_note (insn
, REG_EQUAL
, NULL_RTX
);
4413 set
= single_set (insn
);
4414 if (!set
|| !function_invariant_p (SET_SRC (set
))
4415 || !function_invariant_p (XEXP (note
, 0)))
4416 remove_note (insn
, note
);
4417 } while (insn
!= end
&& (insn
= NEXT_INSN (insn
)));
4419 /* PR46315: when moving insns above a conditional branch, the REG_EQUAL
4420 notes referring to the registers being set might become invalid. */
4426 EXECUTE_IF_SET_IN_BITMAP (merge_set
, 0, i
, bi
)
4427 remove_reg_equal_equiv_notes_for_regno (i
);
4429 BITMAP_FREE (merge_set
);
4432 reorder_insns (head
, end
, PREV_INSN (earliest
));
4435 /* Remove the jump and edge if we can. */
4436 if (other_bb
== new_dest
)
4439 remove_edge (BRANCH_EDGE (test_bb
));
4440 /* ??? Can't merge blocks here, as then_bb is still in use.
4441 At minimum, the merge will get done just before bb-reorder. */
4450 BITMAP_FREE (merge_set
);
4455 /* Main entry point for all if-conversion. AFTER_COMBINE is true if
4456 we are after combine pass. */
4459 if_convert (bool after_combine
)
4466 df_live_add_problem ();
4467 df_live_set_all_dirty ();
4470 /* Record whether we are after combine pass. */
4471 ifcvt_after_combine
= after_combine
;
4472 num_possible_if_blocks
= 0;
4473 num_updated_if_blocks
= 0;
4474 num_true_changes
= 0;
4476 loop_optimizer_init (AVOID_CFG_MODIFICATIONS
);
4477 mark_loop_exit_edges ();
4478 loop_optimizer_finalize ();
4479 free_dominance_info (CDI_DOMINATORS
);
4481 /* Compute postdominators. */
4482 calculate_dominance_info (CDI_POST_DOMINATORS
);
4484 df_set_flags (DF_LR_RUN_DCE
);
4486 /* Go through each of the basic blocks looking for things to convert. If we
4487 have conditional execution, we make multiple passes to allow us to handle
4488 IF-THEN{-ELSE} blocks within other IF-THEN{-ELSE} blocks. */
4493 /* Only need to do dce on the first pass. */
4494 df_clear_flags (DF_LR_RUN_DCE
);
4495 cond_exec_changed_p
= FALSE
;
4498 #ifdef IFCVT_MULTIPLE_DUMPS
4499 if (dump_file
&& pass
> 1)
4500 fprintf (dump_file
, "\n\n========== Pass %d ==========\n", pass
);
4503 FOR_EACH_BB_FN (bb
, cfun
)
4506 while (!df_get_bb_dirty (bb
)
4507 && (new_bb
= find_if_header (bb
, pass
)) != NULL
)
4511 #ifdef IFCVT_MULTIPLE_DUMPS
4512 if (dump_file
&& cond_exec_changed_p
)
4513 print_rtl_with_bb (dump_file
, get_insns (), dump_flags
);
4516 while (cond_exec_changed_p
);
4518 #ifdef IFCVT_MULTIPLE_DUMPS
4520 fprintf (dump_file
, "\n\n========== no more changes\n");
4523 free_dominance_info (CDI_POST_DOMINATORS
);
4528 clear_aux_for_blocks ();
4530 /* If we allocated new pseudos, we must resize the array for sched1. */
4531 if (max_regno
< max_reg_num ())
4532 max_regno
= max_reg_num ();
4534 /* Write the final stats. */
4535 if (dump_file
&& num_possible_if_blocks
> 0)
4538 "\n%d possible IF blocks searched.\n",
4539 num_possible_if_blocks
);
4541 "%d IF blocks converted.\n",
4542 num_updated_if_blocks
);
4544 "%d true changes made.\n\n\n",
4549 df_remove_problem (df_live
);
4551 #ifdef ENABLE_CHECKING
4552 verify_flow_info ();
4556 /* If-conversion and CFG cleanup. */
4558 rest_of_handle_if_conversion (void)
4560 if (flag_if_conversion
)
4564 dump_reg_info (dump_file
);
4565 dump_flow_info (dump_file
, dump_flags
);
4567 cleanup_cfg (CLEANUP_EXPENSIVE
);
4577 const pass_data pass_data_rtl_ifcvt
=
4579 RTL_PASS
, /* type */
4581 OPTGROUP_NONE
, /* optinfo_flags */
4582 TV_IFCVT
, /* tv_id */
4583 0, /* properties_required */
4584 0, /* properties_provided */
4585 0, /* properties_destroyed */
4586 0, /* todo_flags_start */
4587 TODO_df_finish
, /* todo_flags_finish */
4590 class pass_rtl_ifcvt
: public rtl_opt_pass
4593 pass_rtl_ifcvt (gcc::context
*ctxt
)
4594 : rtl_opt_pass (pass_data_rtl_ifcvt
, ctxt
)
4597 /* opt_pass methods: */
4598 virtual bool gate (function
*)
4600 return (optimize
> 0) && dbg_cnt (if_conversion
);
4603 virtual unsigned int execute (function
*)
4605 return rest_of_handle_if_conversion ();
4608 }; // class pass_rtl_ifcvt
4613 make_pass_rtl_ifcvt (gcc::context
*ctxt
)
4615 return new pass_rtl_ifcvt (ctxt
);
4619 /* Rerun if-conversion, as combine may have simplified things enough
4620 to now meet sequence length restrictions. */
4624 const pass_data pass_data_if_after_combine
=
4626 RTL_PASS
, /* type */
4628 OPTGROUP_NONE
, /* optinfo_flags */
4629 TV_IFCVT
, /* tv_id */
4630 0, /* properties_required */
4631 0, /* properties_provided */
4632 0, /* properties_destroyed */
4633 0, /* todo_flags_start */
4634 TODO_df_finish
, /* todo_flags_finish */
4637 class pass_if_after_combine
: public rtl_opt_pass
4640 pass_if_after_combine (gcc::context
*ctxt
)
4641 : rtl_opt_pass (pass_data_if_after_combine
, ctxt
)
4644 /* opt_pass methods: */
4645 virtual bool gate (function
*)
4647 return optimize
> 0 && flag_if_conversion
4648 && dbg_cnt (if_after_combine
);
4651 virtual unsigned int execute (function
*)
4657 }; // class pass_if_after_combine
4662 make_pass_if_after_combine (gcc::context
*ctxt
)
4664 return new pass_if_after_combine (ctxt
);
4670 const pass_data pass_data_if_after_reload
=
4672 RTL_PASS
, /* type */
4674 OPTGROUP_NONE
, /* optinfo_flags */
4675 TV_IFCVT2
, /* tv_id */
4676 0, /* properties_required */
4677 0, /* properties_provided */
4678 0, /* properties_destroyed */
4679 0, /* todo_flags_start */
4680 TODO_df_finish
, /* todo_flags_finish */
4683 class pass_if_after_reload
: public rtl_opt_pass
4686 pass_if_after_reload (gcc::context
*ctxt
)
4687 : rtl_opt_pass (pass_data_if_after_reload
, ctxt
)
4690 /* opt_pass methods: */
4691 virtual bool gate (function
*)
4693 return optimize
> 0 && flag_if_conversion2
4694 && dbg_cnt (if_after_reload
);
4697 virtual unsigned int execute (function
*)
4703 }; // class pass_if_after_reload
4708 make_pass_if_after_reload (gcc::context
*ctxt
)
4710 return new pass_if_after_reload (ctxt
);