1 /* If-conversion support.
2 Copyright (C) 2000, 2001, 2002, 2003 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 2, 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 COPYING. If not, write to the Free
18 Software Foundation, 59 Temple Place - Suite 330, Boston, MA
23 #include "coretypes.h"
30 #include "insn-config.h"
33 #include "hard-reg-set.h"
34 #include "basic-block.h"
45 #ifndef HAVE_conditional_execution
46 #define HAVE_conditional_execution 0
48 #ifndef HAVE_conditional_move
49 #define HAVE_conditional_move 0
60 #ifndef HAVE_conditional_trap
61 #define HAVE_conditional_trap 0
64 #ifndef MAX_CONDITIONAL_EXECUTE
65 #define MAX_CONDITIONAL_EXECUTE (BRANCH_COST + 1)
68 #define NULL_EDGE ((struct edge_def *)NULL)
69 #define NULL_BLOCK ((struct basic_block_def *)NULL)
71 /* # of IF-THEN or IF-THEN-ELSE blocks we looked at */
72 static int num_possible_if_blocks
;
74 /* # of IF-THEN or IF-THEN-ELSE blocks were converted to conditional
76 static int num_updated_if_blocks
;
78 /* # of changes made which require life information to be updated. */
79 static int num_true_changes
;
81 /* Whether conditional execution changes were made. */
82 static int cond_exec_changed_p
;
84 /* True if life data ok at present. */
85 static bool life_data_ok
;
87 /* The post-dominator relation on the original block numbers. */
88 static dominance_info post_dominators
;
90 /* Forward references. */
91 static int count_bb_insns (basic_block
);
92 static rtx
first_active_insn (basic_block
);
93 static rtx
last_active_insn (basic_block
, int);
94 static int seq_contains_jump (rtx
);
95 static basic_block
block_fallthru (basic_block
);
96 static int cond_exec_process_insns (ce_if_block_t
*, rtx
, rtx
, rtx
, rtx
, int);
97 static rtx
cond_exec_get_condition (rtx
);
98 static int cond_exec_process_if_block (ce_if_block_t
*, int);
99 static rtx
noce_get_condition (rtx
, rtx
*);
100 static int noce_operand_ok (rtx
);
101 static int noce_process_if_block (ce_if_block_t
*);
102 static int process_if_block (ce_if_block_t
*);
103 static void merge_if_block (ce_if_block_t
*);
104 static int find_cond_trap (basic_block
, edge
, edge
);
105 static basic_block
find_if_header (basic_block
, int);
106 static int block_jumps_and_fallthru_p (basic_block
, basic_block
);
107 static int find_if_block (ce_if_block_t
*);
108 static int find_if_case_1 (basic_block
, edge
, edge
);
109 static int find_if_case_2 (basic_block
, edge
, edge
);
110 static int find_memory (rtx
*, void *);
111 static int dead_or_predicable (basic_block
, basic_block
, basic_block
,
113 static void noce_emit_move_insn (rtx
, rtx
);
114 static rtx
block_has_only_trap (basic_block
);
115 static void mark_loop_exit_edges (void);
117 /* Sets EDGE_LOOP_EXIT flag for all loop exits. */
119 mark_loop_exit_edges (void)
125 flow_loops_find (&loops
, LOOP_TREE
);
131 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
133 if (find_common_loop (bb
->loop_father
, e
->dest
->loop_father
)
135 e
->flags
|= EDGE_LOOP_EXIT
;
137 e
->flags
&= ~EDGE_LOOP_EXIT
;
142 flow_loops_free (&loops
);
145 /* Count the number of non-jump active insns in BB. */
148 count_bb_insns (basic_block bb
)
155 if (GET_CODE (insn
) == CALL_INSN
|| GET_CODE (insn
) == INSN
)
160 insn
= NEXT_INSN (insn
);
166 /* Return the first non-jump active insn in the basic block. */
169 first_active_insn (basic_block bb
)
173 if (GET_CODE (insn
) == CODE_LABEL
)
177 insn
= NEXT_INSN (insn
);
180 while (GET_CODE (insn
) == NOTE
)
184 insn
= NEXT_INSN (insn
);
187 if (GET_CODE (insn
) == JUMP_INSN
)
193 /* Return the last non-jump active (non-jump) insn in the basic block. */
196 last_active_insn (basic_block bb
, int skip_use_p
)
201 while (GET_CODE (insn
) == NOTE
202 || GET_CODE (insn
) == JUMP_INSN
204 && GET_CODE (insn
) == INSN
205 && GET_CODE (PATTERN (insn
)) == USE
))
209 insn
= PREV_INSN (insn
);
212 if (GET_CODE (insn
) == CODE_LABEL
)
218 /* It is possible, especially when having dealt with multi-word
219 arithmetic, for the expanders to have emitted jumps. Search
220 through the sequence and return TRUE if a jump exists so that
221 we can abort the conversion. */
224 seq_contains_jump (rtx insn
)
228 if (GET_CODE (insn
) == JUMP_INSN
)
230 insn
= NEXT_INSN (insn
);
236 block_fallthru (basic_block bb
)
241 e
!= NULL_EDGE
&& (e
->flags
& EDGE_FALLTHRU
) == 0;
245 return (e
) ? e
->dest
: NULL_BLOCK
;
248 /* Go through a bunch of insns, converting them to conditional
249 execution format if possible. Return TRUE if all of the non-note
250 insns were processed. */
253 cond_exec_process_insns (ce_if_block_t
*ce_info ATTRIBUTE_UNUSED
,
254 /* if block information */rtx start
,
255 /* first insn to look at */rtx end
,
256 /* last insn to look at */rtx test
,
257 /* conditional execution test */rtx prob_val
,
258 /* probability of branch taken. */int mod_ok
)
260 int must_be_last
= FALSE
;
268 for (insn
= start
; ; insn
= NEXT_INSN (insn
))
270 if (GET_CODE (insn
) == NOTE
)
273 if (GET_CODE (insn
) != INSN
&& GET_CODE (insn
) != CALL_INSN
)
276 /* Remove USE insns that get in the way. */
277 if (reload_completed
&& GET_CODE (PATTERN (insn
)) == USE
)
279 /* ??? Ug. Actually unlinking the thing is problematic,
280 given what we'd have to coordinate with our callers. */
281 PUT_CODE (insn
, NOTE
);
282 NOTE_LINE_NUMBER (insn
) = NOTE_INSN_DELETED
;
283 NOTE_SOURCE_FILE (insn
) = 0;
287 /* Last insn wasn't last? */
291 if (modified_in_p (test
, insn
))
298 /* Now build the conditional form of the instruction. */
299 pattern
= PATTERN (insn
);
300 xtest
= copy_rtx (test
);
302 /* If this is already a COND_EXEC, rewrite the test to be an AND of the
304 if (GET_CODE (pattern
) == COND_EXEC
)
306 if (GET_MODE (xtest
) != GET_MODE (COND_EXEC_TEST (pattern
)))
309 xtest
= gen_rtx_AND (GET_MODE (xtest
), xtest
,
310 COND_EXEC_TEST (pattern
));
311 pattern
= COND_EXEC_CODE (pattern
);
314 pattern
= gen_rtx_COND_EXEC (VOIDmode
, xtest
, pattern
);
316 /* If the machine needs to modify the insn being conditionally executed,
317 say for example to force a constant integer operand into a temp
318 register, do so here. */
319 #ifdef IFCVT_MODIFY_INSN
320 IFCVT_MODIFY_INSN (ce_info
, pattern
, insn
);
325 validate_change (insn
, &PATTERN (insn
), pattern
, 1);
327 if (GET_CODE (insn
) == CALL_INSN
&& prob_val
)
328 validate_change (insn
, ®_NOTES (insn
),
329 alloc_EXPR_LIST (REG_BR_PROB
, prob_val
,
330 REG_NOTES (insn
)), 1);
340 /* Return the condition for a jump. Do not do any special processing. */
343 cond_exec_get_condition (rtx jump
)
347 if (any_condjump_p (jump
))
348 test_if
= SET_SRC (pc_set (jump
));
351 cond
= XEXP (test_if
, 0);
353 /* If this branches to JUMP_LABEL when the condition is false,
354 reverse the condition. */
355 if (GET_CODE (XEXP (test_if
, 2)) == LABEL_REF
356 && XEXP (XEXP (test_if
, 2), 0) == JUMP_LABEL (jump
))
358 enum rtx_code rev
= reversed_comparison_code (cond
, jump
);
362 cond
= gen_rtx_fmt_ee (rev
, GET_MODE (cond
), XEXP (cond
, 0),
369 /* Given a simple IF-THEN or IF-THEN-ELSE block, attempt to convert it
370 to conditional execution. Return TRUE if we were successful at
371 converting the block. */
374 cond_exec_process_if_block (ce_if_block_t
* ce_info
,
375 /* if block information */int do_multiple_p
)
377 basic_block test_bb
= ce_info
->test_bb
; /* last test block */
378 basic_block then_bb
= ce_info
->then_bb
; /* THEN */
379 basic_block else_bb
= ce_info
->else_bb
; /* ELSE or NULL */
380 rtx test_expr
; /* expression in IF_THEN_ELSE that is tested */
381 rtx then_start
; /* first insn in THEN block */
382 rtx then_end
; /* last insn + 1 in THEN block */
383 rtx else_start
= NULL_RTX
; /* first insn in ELSE block or NULL */
384 rtx else_end
= NULL_RTX
; /* last insn + 1 in ELSE block */
385 int max
; /* max # of insns to convert. */
386 int then_mod_ok
; /* whether conditional mods are ok in THEN */
387 rtx true_expr
; /* test for else block insns */
388 rtx false_expr
; /* test for then block insns */
389 rtx true_prob_val
; /* probability of else block */
390 rtx false_prob_val
; /* probability of then block */
392 enum rtx_code false_code
;
394 /* If test is comprised of && or || elements, and we've failed at handling
395 all of them together, just use the last test if it is the special case of
396 && elements without an ELSE block. */
397 if (!do_multiple_p
&& ce_info
->num_multiple_test_blocks
)
399 if (else_bb
|| ! ce_info
->and_and_p
)
402 ce_info
->test_bb
= test_bb
= ce_info
->last_test_bb
;
403 ce_info
->num_multiple_test_blocks
= 0;
404 ce_info
->num_and_and_blocks
= 0;
405 ce_info
->num_or_or_blocks
= 0;
408 /* Find the conditional jump to the ELSE or JOIN part, and isolate
410 test_expr
= cond_exec_get_condition (test_bb
->end
);
414 /* If the conditional jump is more than just a conditional jump,
415 then we can not do conditional execution conversion on this block. */
416 if (! onlyjump_p (test_bb
->end
))
419 /* Collect the bounds of where we're to search, skipping any labels, jumps
420 and notes at the beginning and end of the block. Then count the total
421 number of insns and see if it is small enough to convert. */
422 then_start
= first_active_insn (then_bb
);
423 then_end
= last_active_insn (then_bb
, TRUE
);
424 n_insns
= ce_info
->num_then_insns
= count_bb_insns (then_bb
);
425 max
= MAX_CONDITIONAL_EXECUTE
;
430 else_start
= first_active_insn (else_bb
);
431 else_end
= last_active_insn (else_bb
, TRUE
);
432 n_insns
+= ce_info
->num_else_insns
= count_bb_insns (else_bb
);
438 /* Map test_expr/test_jump into the appropriate MD tests to use on
439 the conditionally executed code. */
441 true_expr
= test_expr
;
443 false_code
= reversed_comparison_code (true_expr
, test_bb
->end
);
444 if (false_code
!= UNKNOWN
)
445 false_expr
= gen_rtx_fmt_ee (false_code
, GET_MODE (true_expr
),
446 XEXP (true_expr
, 0), XEXP (true_expr
, 1));
448 false_expr
= NULL_RTX
;
450 #ifdef IFCVT_MODIFY_TESTS
451 /* If the machine description needs to modify the tests, such as setting a
452 conditional execution register from a comparison, it can do so here. */
453 IFCVT_MODIFY_TESTS (ce_info
, true_expr
, false_expr
);
455 /* See if the conversion failed */
456 if (!true_expr
|| !false_expr
)
460 true_prob_val
= find_reg_note (test_bb
->end
, REG_BR_PROB
, NULL_RTX
);
463 true_prob_val
= XEXP (true_prob_val
, 0);
464 false_prob_val
= GEN_INT (REG_BR_PROB_BASE
- INTVAL (true_prob_val
));
467 false_prob_val
= NULL_RTX
;
469 /* If we have && or || tests, do them here. These tests are in the adjacent
470 blocks after the first block containing the test. */
471 if (ce_info
->num_multiple_test_blocks
> 0)
473 basic_block bb
= test_bb
;
474 basic_block last_test_bb
= ce_info
->last_test_bb
;
484 bb
= block_fallthru (bb
);
485 start
= first_active_insn (bb
);
486 end
= last_active_insn (bb
, TRUE
);
488 && ! cond_exec_process_insns (ce_info
, start
, end
, false_expr
,
489 false_prob_val
, FALSE
))
492 /* If the conditional jump is more than just a conditional jump, then
493 we can not do conditional execution conversion on this block. */
494 if (! onlyjump_p (bb
->end
))
497 /* Find the conditional jump and isolate the test. */
498 t
= cond_exec_get_condition (bb
->end
);
502 f
= gen_rtx_fmt_ee (reverse_condition (GET_CODE (t
)),
507 if (ce_info
->and_and_p
)
509 t
= gen_rtx_AND (GET_MODE (t
), true_expr
, t
);
510 f
= gen_rtx_IOR (GET_MODE (t
), false_expr
, f
);
514 t
= gen_rtx_IOR (GET_MODE (t
), true_expr
, t
);
515 f
= gen_rtx_AND (GET_MODE (t
), false_expr
, f
);
518 /* If the machine description needs to modify the tests, such as
519 setting a conditional execution register from a comparison, it can
521 #ifdef IFCVT_MODIFY_MULTIPLE_TESTS
522 IFCVT_MODIFY_MULTIPLE_TESTS (ce_info
, bb
, t
, f
);
524 /* See if the conversion failed */
532 while (bb
!= last_test_bb
);
535 /* For IF-THEN-ELSE blocks, we don't allow modifications of the test
536 on then THEN block. */
537 then_mod_ok
= (else_bb
== NULL_BLOCK
);
539 /* Go through the THEN and ELSE blocks converting the insns if possible
540 to conditional execution. */
544 || ! cond_exec_process_insns (ce_info
, then_start
, then_end
,
545 false_expr
, false_prob_val
,
549 if (else_bb
&& else_end
550 && ! cond_exec_process_insns (ce_info
, else_start
, else_end
,
551 true_expr
, true_prob_val
, TRUE
))
554 /* If we cannot apply the changes, fail. Do not go through the normal fail
555 processing, since apply_change_group will call cancel_changes. */
556 if (! apply_change_group ())
558 #ifdef IFCVT_MODIFY_CANCEL
559 /* Cancel any machine dependent changes. */
560 IFCVT_MODIFY_CANCEL (ce_info
);
565 #ifdef IFCVT_MODIFY_FINAL
566 /* Do any machine dependent final modifications */
567 IFCVT_MODIFY_FINAL (ce_info
);
570 /* Conversion succeeded. */
572 fprintf (rtl_dump_file
, "%d insn%s converted to conditional execution.\n",
573 n_insns
, (n_insns
== 1) ? " was" : "s were");
575 /* Merge the blocks! */
576 merge_if_block (ce_info
);
577 cond_exec_changed_p
= TRUE
;
581 #ifdef IFCVT_MODIFY_CANCEL
582 /* Cancel any machine dependent changes. */
583 IFCVT_MODIFY_CANCEL (ce_info
);
590 /* Used by noce_process_if_block to communicate with its subroutines.
592 The subroutines know that A and B may be evaluated freely. They
593 know that X is a register. They should insert new instructions
594 before cond_earliest. */
601 rtx jump
, cond
, cond_earliest
;
604 static rtx
noce_emit_store_flag (struct noce_if_info
*, rtx
, int, int);
605 static int noce_try_store_flag (struct noce_if_info
*);
606 static int noce_try_addcc (struct noce_if_info
*);
607 static int noce_try_store_flag_constants (struct noce_if_info
*);
608 static int noce_try_store_flag_mask (struct noce_if_info
*);
609 static rtx
noce_emit_cmove (struct noce_if_info
*, rtx
, enum rtx_code
, rtx
,
611 static int noce_try_cmove (struct noce_if_info
*);
612 static int noce_try_cmove_arith (struct noce_if_info
*);
613 static rtx
noce_get_alt_condition (struct noce_if_info
*, rtx
, rtx
*);
614 static int noce_try_minmax (struct noce_if_info
*);
615 static int noce_try_abs (struct noce_if_info
*);
617 /* Helper function for noce_try_store_flag*. */
620 noce_emit_store_flag (struct noce_if_info
*if_info
, rtx x
, int reversep
,
623 rtx cond
= if_info
->cond
;
627 cond_complex
= (! general_operand (XEXP (cond
, 0), VOIDmode
)
628 || ! general_operand (XEXP (cond
, 1), VOIDmode
));
630 /* If earliest == jump, or when the condition is complex, try to
631 build the store_flag insn directly. */
634 cond
= XEXP (SET_SRC (pc_set (if_info
->jump
)), 0);
637 code
= reversed_comparison_code (cond
, if_info
->jump
);
639 code
= GET_CODE (cond
);
641 if ((if_info
->cond_earliest
== if_info
->jump
|| cond_complex
)
642 && (normalize
== 0 || STORE_FLAG_VALUE
== normalize
))
646 tmp
= gen_rtx_fmt_ee (code
, GET_MODE (x
), XEXP (cond
, 0),
648 tmp
= gen_rtx_SET (VOIDmode
, x
, tmp
);
651 tmp
= emit_insn (tmp
);
653 if (recog_memoized (tmp
) >= 0)
659 if_info
->cond_earliest
= if_info
->jump
;
667 /* Don't even try if the comparison operands or the mode of X are weird. */
668 if (cond_complex
|| !SCALAR_INT_MODE_P (GET_MODE (x
)))
671 return emit_store_flag (x
, code
, XEXP (cond
, 0),
672 XEXP (cond
, 1), VOIDmode
,
673 (code
== LTU
|| code
== LEU
674 || code
== GEU
|| code
== GTU
), normalize
);
677 /* Emit instruction to move an rtx into STRICT_LOW_PART. */
679 noce_emit_move_insn (rtx x
, rtx y
)
681 enum machine_mode outmode
, inmode
;
685 if (GET_CODE (x
) != STRICT_LOW_PART
)
687 emit_move_insn (x
, y
);
692 inner
= XEXP (outer
, 0);
693 outmode
= GET_MODE (outer
);
694 inmode
= GET_MODE (inner
);
695 bitpos
= SUBREG_BYTE (outer
) * BITS_PER_UNIT
;
696 store_bit_field (inner
, GET_MODE_BITSIZE (outmode
), bitpos
, outmode
, y
,
697 GET_MODE_BITSIZE (inmode
));
700 /* Convert "if (test) x = 1; else x = 0".
702 Only try 0 and STORE_FLAG_VALUE here. Other combinations will be
703 tried in noce_try_store_flag_constants after noce_try_cmove has had
704 a go at the conversion. */
707 noce_try_store_flag (struct noce_if_info
*if_info
)
712 if (GET_CODE (if_info
->b
) == CONST_INT
713 && INTVAL (if_info
->b
) == STORE_FLAG_VALUE
714 && if_info
->a
== const0_rtx
)
716 else if (if_info
->b
== const0_rtx
717 && GET_CODE (if_info
->a
) == CONST_INT
718 && INTVAL (if_info
->a
) == STORE_FLAG_VALUE
719 && (reversed_comparison_code (if_info
->cond
, if_info
->jump
)
727 target
= noce_emit_store_flag (if_info
, if_info
->x
, reversep
, 0);
730 if (target
!= if_info
->x
)
731 noce_emit_move_insn (if_info
->x
, target
);
735 emit_insn_before_setloc (seq
, if_info
->jump
, INSN_LOCATOR (if_info
->insn_a
));
746 /* Convert "if (test) x = a; else x = b", for A and B constant. */
749 noce_try_store_flag_constants (struct noce_if_info
*if_info
)
753 HOST_WIDE_INT itrue
, ifalse
, diff
, tmp
;
754 int normalize
, can_reverse
;
755 enum machine_mode mode
;
758 && GET_CODE (if_info
->a
) == CONST_INT
759 && GET_CODE (if_info
->b
) == CONST_INT
)
761 mode
= GET_MODE (if_info
->x
);
762 ifalse
= INTVAL (if_info
->a
);
763 itrue
= INTVAL (if_info
->b
);
765 /* Make sure we can represent the difference between the two values. */
766 if ((itrue
- ifalse
> 0)
767 != ((ifalse
< 0) != (itrue
< 0) ? ifalse
< 0 : ifalse
< itrue
))
770 diff
= trunc_int_for_mode (itrue
- ifalse
, mode
);
772 can_reverse
= (reversed_comparison_code (if_info
->cond
, if_info
->jump
)
776 if (diff
== STORE_FLAG_VALUE
|| diff
== -STORE_FLAG_VALUE
)
778 else if (ifalse
== 0 && exact_log2 (itrue
) >= 0
779 && (STORE_FLAG_VALUE
== 1
780 || BRANCH_COST
>= 2))
782 else if (itrue
== 0 && exact_log2 (ifalse
) >= 0 && can_reverse
783 && (STORE_FLAG_VALUE
== 1 || BRANCH_COST
>= 2))
784 normalize
= 1, reversep
= 1;
786 && (STORE_FLAG_VALUE
== -1
787 || BRANCH_COST
>= 2))
789 else if (ifalse
== -1 && can_reverse
790 && (STORE_FLAG_VALUE
== -1 || BRANCH_COST
>= 2))
791 normalize
= -1, reversep
= 1;
792 else if ((BRANCH_COST
>= 2 && STORE_FLAG_VALUE
== -1)
800 tmp
= itrue
; itrue
= ifalse
; ifalse
= tmp
;
801 diff
= trunc_int_for_mode (-diff
, mode
);
805 target
= noce_emit_store_flag (if_info
, if_info
->x
, reversep
, normalize
);
812 /* if (test) x = 3; else x = 4;
813 => x = 3 + (test == 0); */
814 if (diff
== STORE_FLAG_VALUE
|| diff
== -STORE_FLAG_VALUE
)
816 target
= expand_simple_binop (mode
,
817 (diff
== STORE_FLAG_VALUE
819 GEN_INT (ifalse
), target
, if_info
->x
, 0,
823 /* if (test) x = 8; else x = 0;
824 => x = (test != 0) << 3; */
825 else if (ifalse
== 0 && (tmp
= exact_log2 (itrue
)) >= 0)
827 target
= expand_simple_binop (mode
, ASHIFT
,
828 target
, GEN_INT (tmp
), if_info
->x
, 0,
832 /* if (test) x = -1; else x = b;
833 => x = -(test != 0) | b; */
834 else if (itrue
== -1)
836 target
= expand_simple_binop (mode
, IOR
,
837 target
, GEN_INT (ifalse
), if_info
->x
, 0,
841 /* if (test) x = a; else x = b;
842 => x = (-(test != 0) & (b - a)) + a; */
845 target
= expand_simple_binop (mode
, AND
,
846 target
, GEN_INT (diff
), if_info
->x
, 0,
849 target
= expand_simple_binop (mode
, PLUS
,
850 target
, GEN_INT (ifalse
),
851 if_info
->x
, 0, OPTAB_WIDEN
);
860 if (target
!= if_info
->x
)
861 noce_emit_move_insn (if_info
->x
, target
);
866 if (seq_contains_jump (seq
))
869 emit_insn_before_setloc (seq
, if_info
->jump
, INSN_LOCATOR (if_info
->insn_a
));
877 /* Convert "if (test) foo++" into "foo += (test != 0)", and
878 similarly for "foo--". */
881 noce_try_addcc (struct noce_if_info
*if_info
)
884 int subtract
, normalize
;
887 && GET_CODE (if_info
->a
) == PLUS
888 && rtx_equal_p (XEXP (if_info
->a
, 0), if_info
->b
)
889 && (reversed_comparison_code (if_info
->cond
, if_info
->jump
)
892 rtx cond
= if_info
->cond
;
893 enum rtx_code code
= reversed_comparison_code (cond
, if_info
->jump
);
895 /* First try to use addcc pattern. */
896 if (general_operand (XEXP (cond
, 0), VOIDmode
)
897 && general_operand (XEXP (cond
, 1), VOIDmode
))
900 target
= emit_conditional_add (if_info
->x
, code
,
901 XEXP (cond
, 0), XEXP (cond
, 1),
903 if_info
->b
, XEXP (if_info
->a
, 1),
904 GET_MODE (if_info
->x
),
905 (code
== LTU
|| code
== GEU
906 || code
== LEU
|| code
== GTU
));
909 if (target
!= if_info
->x
)
910 noce_emit_move_insn (if_info
->x
, target
);
914 emit_insn_before_setloc (seq
, if_info
->jump
,
915 INSN_LOCATOR (if_info
->insn_a
));
921 /* If that fails, construct conditional increment or decrement using
924 && (XEXP (if_info
->a
, 1) == const1_rtx
925 || XEXP (if_info
->a
, 1) == constm1_rtx
))
928 if (STORE_FLAG_VALUE
== INTVAL (XEXP (if_info
->a
, 1)))
929 subtract
= 0, normalize
= 0;
930 else if (-STORE_FLAG_VALUE
== INTVAL (XEXP (if_info
->a
, 1)))
931 subtract
= 1, normalize
= 0;
933 subtract
= 0, normalize
= INTVAL (XEXP (if_info
->a
, 1));
936 target
= noce_emit_store_flag (if_info
,
937 gen_reg_rtx (GET_MODE (if_info
->x
)),
941 target
= expand_simple_binop (GET_MODE (if_info
->x
),
942 subtract
? MINUS
: PLUS
,
943 if_info
->b
, target
, if_info
->x
,
947 if (target
!= if_info
->x
)
948 noce_emit_move_insn (if_info
->x
, target
);
953 if (seq_contains_jump (seq
))
956 emit_insn_before_setloc (seq
, if_info
->jump
,
957 INSN_LOCATOR (if_info
->insn_a
));
968 /* Convert "if (test) x = 0;" to "x &= -(test == 0);" */
971 noce_try_store_flag_mask (struct noce_if_info
*if_info
)
979 || STORE_FLAG_VALUE
== -1)
980 && ((if_info
->a
== const0_rtx
981 && rtx_equal_p (if_info
->b
, if_info
->x
))
982 || ((reversep
= (reversed_comparison_code (if_info
->cond
,
985 && if_info
->b
== const0_rtx
986 && rtx_equal_p (if_info
->a
, if_info
->x
))))
989 target
= noce_emit_store_flag (if_info
,
990 gen_reg_rtx (GET_MODE (if_info
->x
)),
993 target
= expand_simple_binop (GET_MODE (if_info
->x
), AND
,
994 if_info
->x
, target
, if_info
->x
, 0,
999 if (target
!= if_info
->x
)
1000 noce_emit_move_insn (if_info
->x
, target
);
1005 if (seq_contains_jump (seq
))
1008 emit_insn_before_setloc (seq
, if_info
->jump
,
1009 INSN_LOCATOR (if_info
->insn_a
));
1020 /* Helper function for noce_try_cmove and noce_try_cmove_arith. */
1023 noce_emit_cmove (struct noce_if_info
*if_info
, rtx x
, enum rtx_code code
,
1024 rtx cmp_a
, rtx cmp_b
, rtx vfalse
, rtx vtrue
)
1026 /* If earliest == jump, try to build the cmove insn directly.
1027 This is helpful when combine has created some complex condition
1028 (like for alpha's cmovlbs) that we can't hope to regenerate
1029 through the normal interface. */
1031 if (if_info
->cond_earliest
== if_info
->jump
)
1035 tmp
= gen_rtx_fmt_ee (code
, GET_MODE (if_info
->cond
), cmp_a
, cmp_b
);
1036 tmp
= gen_rtx_IF_THEN_ELSE (GET_MODE (x
), tmp
, vtrue
, vfalse
);
1037 tmp
= gen_rtx_SET (VOIDmode
, x
, tmp
);
1040 tmp
= emit_insn (tmp
);
1042 if (recog_memoized (tmp
) >= 0)
1054 /* Don't even try if the comparison operands are weird. */
1055 if (! general_operand (cmp_a
, GET_MODE (cmp_a
))
1056 || ! general_operand (cmp_b
, GET_MODE (cmp_b
)))
1059 #if HAVE_conditional_move
1060 return emit_conditional_move (x
, code
, cmp_a
, cmp_b
, VOIDmode
,
1061 vtrue
, vfalse
, GET_MODE (x
),
1062 (code
== LTU
|| code
== GEU
1063 || code
== LEU
|| code
== GTU
));
1065 /* We'll never get here, as noce_process_if_block doesn't call the
1066 functions involved. Ifdef code, however, should be discouraged
1067 because it leads to typos in the code not selected. However,
1068 emit_conditional_move won't exist either. */
1073 /* Try only simple constants and registers here. More complex cases
1074 are handled in noce_try_cmove_arith after noce_try_store_flag_arith
1075 has had a go at it. */
1078 noce_try_cmove (struct noce_if_info
*if_info
)
1083 if ((CONSTANT_P (if_info
->a
) || register_operand (if_info
->a
, VOIDmode
))
1084 && (CONSTANT_P (if_info
->b
) || register_operand (if_info
->b
, VOIDmode
)))
1088 code
= GET_CODE (if_info
->cond
);
1089 target
= noce_emit_cmove (if_info
, if_info
->x
, code
,
1090 XEXP (if_info
->cond
, 0),
1091 XEXP (if_info
->cond
, 1),
1092 if_info
->a
, if_info
->b
);
1096 if (target
!= if_info
->x
)
1097 noce_emit_move_insn (if_info
->x
, target
);
1101 emit_insn_before_setloc (seq
, if_info
->jump
,
1102 INSN_LOCATOR (if_info
->insn_a
));
1115 /* Try more complex cases involving conditional_move. */
1118 noce_try_cmove_arith (struct noce_if_info
*if_info
)
1128 /* A conditional move from two memory sources is equivalent to a
1129 conditional on their addresses followed by a load. Don't do this
1130 early because it'll screw alias analysis. Note that we've
1131 already checked for no side effects. */
1132 if (! no_new_pseudos
&& cse_not_expected
1133 && GET_CODE (a
) == MEM
&& GET_CODE (b
) == MEM
1134 && BRANCH_COST
>= 5)
1138 x
= gen_reg_rtx (Pmode
);
1142 /* ??? We could handle this if we knew that a load from A or B could
1143 not fault. This is also true if we've already loaded
1144 from the address along the path from ENTRY. */
1145 else if (may_trap_p (a
) || may_trap_p (b
))
1148 /* if (test) x = a + b; else x = c - d;
1155 code
= GET_CODE (if_info
->cond
);
1156 insn_a
= if_info
->insn_a
;
1157 insn_b
= if_info
->insn_b
;
1159 /* Possibly rearrange operands to make things come out more natural. */
1160 if (reversed_comparison_code (if_info
->cond
, if_info
->jump
) != UNKNOWN
)
1163 if (rtx_equal_p (b
, x
))
1165 else if (general_operand (b
, GET_MODE (b
)))
1170 code
= reversed_comparison_code (if_info
->cond
, if_info
->jump
);
1171 tmp
= a
, a
= b
, b
= tmp
;
1172 tmp
= insn_a
, insn_a
= insn_b
, insn_b
= tmp
;
1178 /* If either operand is complex, load it into a register first.
1179 The best way to do this is to copy the original insn. In this
1180 way we preserve any clobbers etc that the insn may have had.
1181 This is of course not possible in the IS_MEM case. */
1182 if (! general_operand (a
, GET_MODE (a
)))
1187 goto end_seq_and_fail
;
1191 tmp
= gen_reg_rtx (GET_MODE (a
));
1192 tmp
= emit_insn (gen_rtx_SET (VOIDmode
, tmp
, a
));
1195 goto end_seq_and_fail
;
1198 a
= gen_reg_rtx (GET_MODE (a
));
1199 tmp
= copy_rtx (insn_a
);
1200 set
= single_set (tmp
);
1202 tmp
= emit_insn (PATTERN (tmp
));
1204 if (recog_memoized (tmp
) < 0)
1205 goto end_seq_and_fail
;
1207 if (! general_operand (b
, GET_MODE (b
)))
1212 goto end_seq_and_fail
;
1216 tmp
= gen_reg_rtx (GET_MODE (b
));
1217 tmp
= emit_insn (gen_rtx_SET (VOIDmode
, tmp
, b
));
1220 goto end_seq_and_fail
;
1223 b
= gen_reg_rtx (GET_MODE (b
));
1224 tmp
= copy_rtx (insn_b
);
1225 set
= single_set (tmp
);
1227 tmp
= emit_insn (PATTERN (tmp
));
1229 if (recog_memoized (tmp
) < 0)
1230 goto end_seq_and_fail
;
1233 target
= noce_emit_cmove (if_info
, x
, code
, XEXP (if_info
->cond
, 0),
1234 XEXP (if_info
->cond
, 1), a
, b
);
1237 goto end_seq_and_fail
;
1239 /* If we're handling a memory for above, emit the load now. */
1242 tmp
= gen_rtx_MEM (GET_MODE (if_info
->x
), target
);
1244 /* Copy over flags as appropriate. */
1245 if (MEM_VOLATILE_P (if_info
->a
) || MEM_VOLATILE_P (if_info
->b
))
1246 MEM_VOLATILE_P (tmp
) = 1;
1247 if (MEM_IN_STRUCT_P (if_info
->a
) && MEM_IN_STRUCT_P (if_info
->b
))
1248 MEM_IN_STRUCT_P (tmp
) = 1;
1249 if (MEM_SCALAR_P (if_info
->a
) && MEM_SCALAR_P (if_info
->b
))
1250 MEM_SCALAR_P (tmp
) = 1;
1251 if (MEM_ALIAS_SET (if_info
->a
) == MEM_ALIAS_SET (if_info
->b
))
1252 set_mem_alias_set (tmp
, MEM_ALIAS_SET (if_info
->a
));
1254 MIN (MEM_ALIGN (if_info
->a
), MEM_ALIGN (if_info
->b
)));
1256 noce_emit_move_insn (if_info
->x
, tmp
);
1258 else if (target
!= x
)
1259 noce_emit_move_insn (x
, target
);
1263 emit_insn_before_setloc (tmp
, if_info
->jump
, INSN_LOCATOR (if_info
->insn_a
));
1271 /* For most cases, the simplified condition we found is the best
1272 choice, but this is not the case for the min/max/abs transforms.
1273 For these we wish to know that it is A or B in the condition. */
1276 noce_get_alt_condition (struct noce_if_info
*if_info
, rtx target
,
1279 rtx cond
, set
, insn
;
1282 /* If target is already mentioned in the known condition, return it. */
1283 if (reg_mentioned_p (target
, if_info
->cond
))
1285 *earliest
= if_info
->cond_earliest
;
1286 return if_info
->cond
;
1289 set
= pc_set (if_info
->jump
);
1290 cond
= XEXP (SET_SRC (set
), 0);
1292 = GET_CODE (XEXP (SET_SRC (set
), 2)) == LABEL_REF
1293 && XEXP (XEXP (SET_SRC (set
), 2), 0) == JUMP_LABEL (if_info
->jump
);
1295 /* If we're looking for a constant, try to make the conditional
1296 have that constant in it. There are two reasons why it may
1297 not have the constant we want:
1299 1. GCC may have needed to put the constant in a register, because
1300 the target can't compare directly against that constant. For
1301 this case, we look for a SET immediately before the comparison
1302 that puts a constant in that register.
1304 2. GCC may have canonicalized the conditional, for example
1305 replacing "if x < 4" with "if x <= 3". We can undo that (or
1306 make equivalent types of changes) to get the constants we need
1307 if they're off by one in the right direction. */
1309 if (GET_CODE (target
) == CONST_INT
)
1311 enum rtx_code code
= GET_CODE (if_info
->cond
);
1312 rtx op_a
= XEXP (if_info
->cond
, 0);
1313 rtx op_b
= XEXP (if_info
->cond
, 1);
1316 /* First, look to see if we put a constant in a register. */
1317 prev_insn
= PREV_INSN (if_info
->cond_earliest
);
1319 && INSN_P (prev_insn
)
1320 && GET_CODE (PATTERN (prev_insn
)) == SET
)
1322 rtx src
= find_reg_equal_equiv_note (prev_insn
);
1324 src
= SET_SRC (PATTERN (prev_insn
));
1325 if (GET_CODE (src
) == CONST_INT
)
1327 if (rtx_equal_p (op_a
, SET_DEST (PATTERN (prev_insn
))))
1329 else if (rtx_equal_p (op_b
, SET_DEST (PATTERN (prev_insn
))))
1332 if (GET_CODE (op_a
) == CONST_INT
)
1337 code
= swap_condition (code
);
1342 /* Now, look to see if we can get the right constant by
1343 adjusting the conditional. */
1344 if (GET_CODE (op_b
) == CONST_INT
)
1346 HOST_WIDE_INT desired_val
= INTVAL (target
);
1347 HOST_WIDE_INT actual_val
= INTVAL (op_b
);
1352 if (actual_val
== desired_val
+ 1)
1355 op_b
= GEN_INT (desired_val
);
1359 if (actual_val
== desired_val
- 1)
1362 op_b
= GEN_INT (desired_val
);
1366 if (actual_val
== desired_val
- 1)
1369 op_b
= GEN_INT (desired_val
);
1373 if (actual_val
== desired_val
+ 1)
1376 op_b
= GEN_INT (desired_val
);
1384 /* If we made any changes, generate a new conditional that is
1385 equivalent to what we started with, but has the right
1387 if (code
!= GET_CODE (if_info
->cond
)
1388 || op_a
!= XEXP (if_info
->cond
, 0)
1389 || op_b
!= XEXP (if_info
->cond
, 1))
1391 cond
= gen_rtx_fmt_ee (code
, GET_MODE (cond
), op_a
, op_b
);
1392 *earliest
= if_info
->cond_earliest
;
1397 cond
= canonicalize_condition (if_info
->jump
, cond
, reverse
,
1398 earliest
, target
, false);
1399 if (! cond
|| ! reg_mentioned_p (target
, cond
))
1402 /* We almost certainly searched back to a different place.
1403 Need to re-verify correct lifetimes. */
1405 /* X may not be mentioned in the range (cond_earliest, jump]. */
1406 for (insn
= if_info
->jump
; insn
!= *earliest
; insn
= PREV_INSN (insn
))
1407 if (INSN_P (insn
) && reg_overlap_mentioned_p (if_info
->x
, PATTERN (insn
)))
1410 /* A and B may not be modified in the range [cond_earliest, jump). */
1411 for (insn
= *earliest
; insn
!= if_info
->jump
; insn
= NEXT_INSN (insn
))
1413 && (modified_in_p (if_info
->a
, insn
)
1414 || modified_in_p (if_info
->b
, insn
)))
1420 /* Convert "if (a < b) x = a; else x = b;" to "x = min(a, b);", etc. */
1423 noce_try_minmax (struct noce_if_info
*if_info
)
1425 rtx cond
, earliest
, target
, seq
;
1426 enum rtx_code code
, op
;
1429 /* ??? Can't guarantee that expand_binop won't create pseudos. */
1433 /* ??? Reject modes with NaNs or signed zeros since we don't know how
1434 they will be resolved with an SMIN/SMAX. It wouldn't be too hard
1435 to get the target to tell us... */
1436 if (HONOR_SIGNED_ZEROS (GET_MODE (if_info
->x
))
1437 || HONOR_NANS (GET_MODE (if_info
->x
)))
1440 cond
= noce_get_alt_condition (if_info
, if_info
->a
, &earliest
);
1444 /* Verify the condition is of the form we expect, and canonicalize
1445 the comparison code. */
1446 code
= GET_CODE (cond
);
1447 if (rtx_equal_p (XEXP (cond
, 0), if_info
->a
))
1449 if (! rtx_equal_p (XEXP (cond
, 1), if_info
->b
))
1452 else if (rtx_equal_p (XEXP (cond
, 1), if_info
->a
))
1454 if (! rtx_equal_p (XEXP (cond
, 0), if_info
->b
))
1456 code
= swap_condition (code
);
1461 /* Determine what sort of operation this is. Note that the code is for
1462 a taken branch, so the code->operation mapping appears backwards. */
1495 target
= expand_simple_binop (GET_MODE (if_info
->x
), op
,
1496 if_info
->a
, if_info
->b
,
1497 if_info
->x
, unsignedp
, OPTAB_WIDEN
);
1503 if (target
!= if_info
->x
)
1504 noce_emit_move_insn (if_info
->x
, target
);
1509 if (seq_contains_jump (seq
))
1512 emit_insn_before_setloc (seq
, if_info
->jump
, INSN_LOCATOR (if_info
->insn_a
));
1513 if_info
->cond
= cond
;
1514 if_info
->cond_earliest
= earliest
;
1519 /* Convert "if (a < 0) x = -a; else x = a;" to "x = abs(a);", etc. */
1522 noce_try_abs (struct noce_if_info
*if_info
)
1524 rtx cond
, earliest
, target
, seq
, a
, b
, c
;
1527 /* ??? Can't guarantee that expand_binop won't create pseudos. */
1531 /* Recognize A and B as constituting an ABS or NABS. */
1534 if (GET_CODE (a
) == NEG
&& rtx_equal_p (XEXP (a
, 0), b
))
1536 else if (GET_CODE (b
) == NEG
&& rtx_equal_p (XEXP (b
, 0), a
))
1538 c
= a
; a
= b
; b
= c
;
1544 cond
= noce_get_alt_condition (if_info
, b
, &earliest
);
1548 /* Verify the condition is of the form we expect. */
1549 if (rtx_equal_p (XEXP (cond
, 0), b
))
1551 else if (rtx_equal_p (XEXP (cond
, 1), b
))
1556 /* Verify that C is zero. Search backward through the block for
1557 a REG_EQUAL note if necessary. */
1560 rtx insn
, note
= NULL
;
1561 for (insn
= earliest
;
1562 insn
!= if_info
->test_bb
->head
;
1563 insn
= PREV_INSN (insn
))
1565 && ((note
= find_reg_note (insn
, REG_EQUAL
, c
))
1566 || (note
= find_reg_note (insn
, REG_EQUIV
, c
))))
1572 if (GET_CODE (c
) == MEM
1573 && GET_CODE (XEXP (c
, 0)) == SYMBOL_REF
1574 && CONSTANT_POOL_ADDRESS_P (XEXP (c
, 0)))
1575 c
= get_pool_constant (XEXP (c
, 0));
1577 /* Work around funny ideas get_condition has wrt canonicalization.
1578 Note that these rtx constants are known to be CONST_INT, and
1579 therefore imply integer comparisons. */
1580 if (c
== constm1_rtx
&& GET_CODE (cond
) == GT
)
1582 else if (c
== const1_rtx
&& GET_CODE (cond
) == LT
)
1584 else if (c
!= CONST0_RTX (GET_MODE (b
)))
1587 /* Determine what sort of operation this is. */
1588 switch (GET_CODE (cond
))
1607 target
= expand_abs_nojump (GET_MODE (if_info
->x
), b
, if_info
->x
, 1);
1609 /* ??? It's a quandry whether cmove would be better here, especially
1610 for integers. Perhaps combine will clean things up. */
1611 if (target
&& negate
)
1612 target
= expand_simple_unop (GET_MODE (target
), NEG
, target
, if_info
->x
, 0);
1620 if (target
!= if_info
->x
)
1621 noce_emit_move_insn (if_info
->x
, target
);
1626 if (seq_contains_jump (seq
))
1629 emit_insn_before_setloc (seq
, if_info
->jump
, INSN_LOCATOR (if_info
->insn_a
));
1630 if_info
->cond
= cond
;
1631 if_info
->cond_earliest
= earliest
;
1636 /* Similar to get_condition, only the resulting condition must be
1637 valid at JUMP, instead of at EARLIEST. */
1640 noce_get_condition (rtx jump
, rtx
*earliest
)
1642 rtx cond
, set
, tmp
, insn
;
1645 if (! any_condjump_p (jump
))
1648 set
= pc_set (jump
);
1650 /* If this branches to JUMP_LABEL when the condition is false,
1651 reverse the condition. */
1652 reverse
= (GET_CODE (XEXP (SET_SRC (set
), 2)) == LABEL_REF
1653 && XEXP (XEXP (SET_SRC (set
), 2), 0) == JUMP_LABEL (jump
));
1655 /* If the condition variable is a register and is MODE_INT, accept it. */
1657 cond
= XEXP (SET_SRC (set
), 0);
1658 tmp
= XEXP (cond
, 0);
1659 if (REG_P (tmp
) && GET_MODE_CLASS (GET_MODE (tmp
)) == MODE_INT
)
1664 cond
= gen_rtx_fmt_ee (reverse_condition (GET_CODE (cond
)),
1665 GET_MODE (cond
), tmp
, XEXP (cond
, 1));
1669 /* Otherwise, fall back on canonicalize_condition to do the dirty
1670 work of manipulating MODE_CC values and COMPARE rtx codes. */
1672 tmp
= canonicalize_condition (jump
, cond
, reverse
, earliest
, NULL_RTX
,
1677 /* We are going to insert code before JUMP, not before EARLIEST.
1678 We must therefore be certain that the given condition is valid
1679 at JUMP by virtue of not having been modified since. */
1680 for (insn
= *earliest
; insn
!= jump
; insn
= NEXT_INSN (insn
))
1681 if (INSN_P (insn
) && modified_in_p (tmp
, insn
))
1686 /* The condition was modified. See if we can get a partial result
1687 that doesn't follow all the reversals. Perhaps combine can fold
1688 them together later. */
1689 tmp
= XEXP (tmp
, 0);
1690 if (!REG_P (tmp
) || GET_MODE_CLASS (GET_MODE (tmp
)) != MODE_INT
)
1692 tmp
= canonicalize_condition (jump
, cond
, reverse
, earliest
, tmp
,
1697 /* For sanity's sake, re-validate the new result. */
1698 for (insn
= *earliest
; insn
!= jump
; insn
= NEXT_INSN (insn
))
1699 if (INSN_P (insn
) && modified_in_p (tmp
, insn
))
1705 /* Return true if OP is ok for if-then-else processing. */
1708 noce_operand_ok (rtx op
)
1710 /* We special-case memories, so handle any of them with
1711 no address side effects. */
1712 if (GET_CODE (op
) == MEM
)
1713 return ! side_effects_p (XEXP (op
, 0));
1715 if (side_effects_p (op
))
1718 return ! may_trap_p (op
);
1721 /* Given a simple IF-THEN or IF-THEN-ELSE block, attempt to convert it
1722 without using conditional execution. Return TRUE if we were
1723 successful at converting the block. */
1726 noce_process_if_block (struct ce_if_block
* ce_info
)
1728 basic_block test_bb
= ce_info
->test_bb
; /* test block */
1729 basic_block then_bb
= ce_info
->then_bb
; /* THEN */
1730 basic_block else_bb
= ce_info
->else_bb
; /* ELSE or NULL */
1731 struct noce_if_info if_info
;
1734 rtx orig_x
, x
, a
, b
;
1737 /* We're looking for patterns of the form
1739 (1) if (...) x = a; else x = b;
1740 (2) x = b; if (...) x = a;
1741 (3) if (...) x = a; // as if with an initial x = x.
1743 The later patterns require jumps to be more expensive.
1745 ??? For future expansion, look for multiple X in such patterns. */
1747 /* If test is comprised of && or || elements, don't handle it unless it is
1748 the special case of && elements without an ELSE block. */
1749 if (ce_info
->num_multiple_test_blocks
)
1751 if (else_bb
|| ! ce_info
->and_and_p
)
1754 ce_info
->test_bb
= test_bb
= ce_info
->last_test_bb
;
1755 ce_info
->num_multiple_test_blocks
= 0;
1756 ce_info
->num_and_and_blocks
= 0;
1757 ce_info
->num_or_or_blocks
= 0;
1760 /* If this is not a standard conditional jump, we can't parse it. */
1761 jump
= test_bb
->end
;
1762 cond
= noce_get_condition (jump
, &if_info
.cond_earliest
);
1766 /* If the conditional jump is more than just a conditional
1767 jump, then we can not do if-conversion on this block. */
1768 if (! onlyjump_p (jump
))
1771 /* We must be comparing objects whose modes imply the size. */
1772 if (GET_MODE (XEXP (cond
, 0)) == BLKmode
)
1775 /* Look for one of the potential sets. */
1776 insn_a
= first_active_insn (then_bb
);
1778 || insn_a
!= last_active_insn (then_bb
, FALSE
)
1779 || (set_a
= single_set (insn_a
)) == NULL_RTX
)
1782 x
= SET_DEST (set_a
);
1783 a
= SET_SRC (set_a
);
1785 /* Look for the other potential set. Make sure we've got equivalent
1787 /* ??? This is overconservative. Storing to two different mems is
1788 as easy as conditionally computing the address. Storing to a
1789 single mem merely requires a scratch memory to use as one of the
1790 destination addresses; often the memory immediately below the
1791 stack pointer is available for this. */
1795 insn_b
= first_active_insn (else_bb
);
1797 || insn_b
!= last_active_insn (else_bb
, FALSE
)
1798 || (set_b
= single_set (insn_b
)) == NULL_RTX
1799 || ! rtx_equal_p (x
, SET_DEST (set_b
)))
1804 insn_b
= prev_nonnote_insn (if_info
.cond_earliest
);
1805 /* We're going to be moving the evaluation of B down from above
1806 COND_EARLIEST to JUMP. Make sure the relevant data is still
1809 || GET_CODE (insn_b
) != INSN
1810 || (set_b
= single_set (insn_b
)) == NULL_RTX
1811 || ! rtx_equal_p (x
, SET_DEST (set_b
))
1812 || reg_overlap_mentioned_p (x
, SET_SRC (set_b
))
1813 || modified_between_p (SET_SRC (set_b
),
1814 PREV_INSN (if_info
.cond_earliest
), jump
)
1815 /* Likewise with X. In particular this can happen when
1816 noce_get_condition looks farther back in the instruction
1817 stream than one might expect. */
1818 || reg_overlap_mentioned_p (x
, cond
)
1819 || reg_overlap_mentioned_p (x
, a
)
1820 || modified_between_p (x
, PREV_INSN (if_info
.cond_earliest
), jump
))
1821 insn_b
= set_b
= NULL_RTX
;
1824 /* If x has side effects then only the if-then-else form is safe to
1825 convert. But even in that case we would need to restore any notes
1826 (such as REG_INC) at then end. That can be tricky if
1827 noce_emit_move_insn expands to more than one insn, so disable the
1828 optimization entirely for now if there are side effects. */
1829 if (side_effects_p (x
))
1832 b
= (set_b
? SET_SRC (set_b
) : x
);
1834 /* Only operate on register destinations, and even then avoid extending
1835 the lifetime of hard registers on small register class machines. */
1837 if (GET_CODE (x
) != REG
1838 || (SMALL_REGISTER_CLASSES
1839 && REGNO (x
) < FIRST_PSEUDO_REGISTER
))
1841 if (no_new_pseudos
|| GET_MODE (x
) == BLKmode
)
1843 x
= gen_reg_rtx (GET_MODE (GET_CODE (x
) == STRICT_LOW_PART
1844 ? XEXP (x
, 0) : x
));
1847 /* Don't operate on sources that may trap or are volatile. */
1848 if (! noce_operand_ok (a
) || ! noce_operand_ok (b
))
1851 /* Set up the info block for our subroutines. */
1852 if_info
.test_bb
= test_bb
;
1853 if_info
.cond
= cond
;
1854 if_info
.jump
= jump
;
1855 if_info
.insn_a
= insn_a
;
1856 if_info
.insn_b
= insn_b
;
1861 /* Try optimizations in some approximation of a useful order. */
1862 /* ??? Should first look to see if X is live incoming at all. If it
1863 isn't, we don't need anything but an unconditional set. */
1865 /* Look and see if A and B are really the same. Avoid creating silly
1866 cmove constructs that no one will fix up later. */
1867 if (rtx_equal_p (a
, b
))
1869 /* If we have an INSN_B, we don't have to create any new rtl. Just
1870 move the instruction that we already have. If we don't have an
1871 INSN_B, that means that A == X, and we've got a noop move. In
1872 that case don't do anything and let the code below delete INSN_A. */
1873 if (insn_b
&& else_bb
)
1877 if (else_bb
&& insn_b
== else_bb
->end
)
1878 else_bb
->end
= PREV_INSN (insn_b
);
1879 reorder_insns (insn_b
, insn_b
, PREV_INSN (jump
));
1881 /* If there was a REG_EQUAL note, delete it since it may have been
1882 true due to this insn being after a jump. */
1883 if ((note
= find_reg_note (insn_b
, REG_EQUAL
, NULL_RTX
)) != 0)
1884 remove_note (insn_b
, note
);
1888 /* If we have "x = b; if (...) x = a;", and x has side-effects, then
1889 x must be executed twice. */
1890 else if (insn_b
&& side_effects_p (orig_x
))
1897 if (noce_try_store_flag (&if_info
))
1899 if (noce_try_minmax (&if_info
))
1901 if (noce_try_abs (&if_info
))
1903 if (HAVE_conditional_move
1904 && noce_try_cmove (&if_info
))
1906 if (! HAVE_conditional_execution
)
1908 if (noce_try_store_flag_constants (&if_info
))
1910 if (noce_try_addcc (&if_info
))
1912 if (noce_try_store_flag_mask (&if_info
))
1914 if (HAVE_conditional_move
1915 && noce_try_cmove_arith (&if_info
))
1922 /* The original sets may now be killed. */
1923 delete_insn (insn_a
);
1925 /* Several special cases here: First, we may have reused insn_b above,
1926 in which case insn_b is now NULL. Second, we want to delete insn_b
1927 if it came from the ELSE block, because follows the now correct
1928 write that appears in the TEST block. However, if we got insn_b from
1929 the TEST block, it may in fact be loading data needed for the comparison.
1930 We'll let life_analysis remove the insn if it's really dead. */
1931 if (insn_b
&& else_bb
)
1932 delete_insn (insn_b
);
1934 /* The new insns will have been inserted immediately before the jump. We
1935 should be able to remove the jump with impunity, but the condition itself
1936 may have been modified by gcse to be shared across basic blocks. */
1939 /* If we used a temporary, fix it up now. */
1943 noce_emit_move_insn (copy_rtx (orig_x
), x
);
1944 insn_b
= get_insns ();
1947 emit_insn_after_setloc (insn_b
, test_bb
->end
, INSN_LOCATOR (insn_a
));
1950 /* Merge the blocks! */
1951 merge_if_block (ce_info
);
1956 /* Attempt to convert an IF-THEN or IF-THEN-ELSE block into
1957 straight line code. Return true if successful. */
1960 process_if_block (struct ce_if_block
* ce_info
)
1962 if (! reload_completed
1963 && noce_process_if_block (ce_info
))
1966 if (HAVE_conditional_execution
&& reload_completed
)
1968 /* If we have && and || tests, try to first handle combining the && and
1969 || tests into the conditional code, and if that fails, go back and
1970 handle it without the && and ||, which at present handles the && case
1971 if there was no ELSE block. */
1972 if (cond_exec_process_if_block (ce_info
, TRUE
))
1975 if (ce_info
->num_multiple_test_blocks
)
1979 if (cond_exec_process_if_block (ce_info
, FALSE
))
1987 /* Merge the blocks and mark for local life update. */
1990 merge_if_block (struct ce_if_block
* ce_info
)
1992 basic_block test_bb
= ce_info
->test_bb
; /* last test block */
1993 basic_block then_bb
= ce_info
->then_bb
; /* THEN */
1994 basic_block else_bb
= ce_info
->else_bb
; /* ELSE or NULL */
1995 basic_block join_bb
= ce_info
->join_bb
; /* join block */
1996 basic_block combo_bb
;
1998 /* All block merging is done into the lower block numbers. */
2002 /* Merge any basic blocks to handle && and || subtests. Each of
2003 the blocks are on the fallthru path from the predecessor block. */
2004 if (ce_info
->num_multiple_test_blocks
> 0)
2006 basic_block bb
= test_bb
;
2007 basic_block last_test_bb
= ce_info
->last_test_bb
;
2008 basic_block fallthru
= block_fallthru (bb
);
2013 fallthru
= block_fallthru (bb
);
2014 if (post_dominators
)
2015 delete_from_dominance_info (post_dominators
, bb
);
2016 merge_blocks (combo_bb
, bb
);
2019 while (bb
!= last_test_bb
);
2022 /* Merge TEST block into THEN block. Normally the THEN block won't have a
2023 label, but it might if there were || tests. That label's count should be
2024 zero, and it normally should be removed. */
2028 if (combo_bb
->global_live_at_end
)
2029 COPY_REG_SET (combo_bb
->global_live_at_end
,
2030 then_bb
->global_live_at_end
);
2031 if (post_dominators
)
2032 delete_from_dominance_info (post_dominators
, then_bb
);
2033 merge_blocks (combo_bb
, then_bb
);
2037 /* The ELSE block, if it existed, had a label. That label count
2038 will almost always be zero, but odd things can happen when labels
2039 get their addresses taken. */
2042 if (post_dominators
)
2043 delete_from_dominance_info (post_dominators
, else_bb
);
2044 merge_blocks (combo_bb
, else_bb
);
2048 /* If there was no join block reported, that means it was not adjacent
2049 to the others, and so we cannot merge them. */
2053 rtx last
= combo_bb
->end
;
2055 /* The outgoing edge for the current COMBO block should already
2056 be correct. Verify this. */
2057 if (combo_bb
->succ
== NULL_EDGE
)
2059 if (find_reg_note (last
, REG_NORETURN
, NULL
))
2061 else if (GET_CODE (last
) == INSN
2062 && GET_CODE (PATTERN (last
)) == TRAP_IF
2063 && TRAP_CONDITION (PATTERN (last
)) == const_true_rtx
)
2069 /* There should still be something at the end of the THEN or ELSE
2070 blocks taking us to our final destination. */
2071 else if (GET_CODE (last
) == JUMP_INSN
)
2073 else if (combo_bb
->succ
->dest
== EXIT_BLOCK_PTR
2074 && GET_CODE (last
) == CALL_INSN
2075 && SIBLING_CALL_P (last
))
2077 else if ((combo_bb
->succ
->flags
& EDGE_EH
)
2078 && can_throw_internal (last
))
2084 /* The JOIN block may have had quite a number of other predecessors too.
2085 Since we've already merged the TEST, THEN and ELSE blocks, we should
2086 have only one remaining edge from our if-then-else diamond. If there
2087 is more than one remaining edge, it must come from elsewhere. There
2088 may be zero incoming edges if the THEN block didn't actually join
2089 back up (as with a call to abort). */
2090 else if ((join_bb
->pred
== NULL
2091 || join_bb
->pred
->pred_next
== NULL
)
2092 && join_bb
!= EXIT_BLOCK_PTR
)
2094 /* We can merge the JOIN. */
2095 if (combo_bb
->global_live_at_end
)
2096 COPY_REG_SET (combo_bb
->global_live_at_end
,
2097 join_bb
->global_live_at_end
);
2099 if (post_dominators
)
2100 delete_from_dominance_info (post_dominators
, join_bb
);
2101 merge_blocks (combo_bb
, join_bb
);
2106 /* We cannot merge the JOIN. */
2108 /* The outgoing edge for the current COMBO block should already
2109 be correct. Verify this. */
2110 if (combo_bb
->succ
->succ_next
!= NULL_EDGE
2111 || combo_bb
->succ
->dest
!= join_bb
)
2114 /* Remove the jump and cruft from the end of the COMBO block. */
2115 if (join_bb
!= EXIT_BLOCK_PTR
)
2116 tidy_fallthru_edge (combo_bb
->succ
, combo_bb
, join_bb
);
2119 num_updated_if_blocks
++;
2122 /* Find a block ending in a simple IF condition and try to transform it
2123 in some way. When converting a multi-block condition, put the new code
2124 in the first such block and delete the rest. Return a pointer to this
2125 first block if some transformation was done. Return NULL otherwise. */
2128 find_if_header (basic_block test_bb
, int pass
)
2130 ce_if_block_t ce_info
;
2134 /* The kind of block we're looking for has exactly two successors. */
2135 if ((then_edge
= test_bb
->succ
) == NULL_EDGE
2136 || (else_edge
= then_edge
->succ_next
) == NULL_EDGE
2137 || else_edge
->succ_next
!= NULL_EDGE
)
2140 /* Neither edge should be abnormal. */
2141 if ((then_edge
->flags
& EDGE_COMPLEX
)
2142 || (else_edge
->flags
& EDGE_COMPLEX
))
2145 /* Nor exit the loop. */
2146 if ((then_edge
->flags
& EDGE_LOOP_EXIT
)
2147 || (else_edge
->flags
& EDGE_LOOP_EXIT
))
2150 /* The THEN edge is canonically the one that falls through. */
2151 if (then_edge
->flags
& EDGE_FALLTHRU
)
2153 else if (else_edge
->flags
& EDGE_FALLTHRU
)
2156 else_edge
= then_edge
;
2160 /* Otherwise this must be a multiway branch of some sort. */
2163 memset (&ce_info
, '\0', sizeof (ce_info
));
2164 ce_info
.test_bb
= test_bb
;
2165 ce_info
.then_bb
= then_edge
->dest
;
2166 ce_info
.else_bb
= else_edge
->dest
;
2167 ce_info
.pass
= pass
;
2169 #ifdef IFCVT_INIT_EXTRA_FIELDS
2170 IFCVT_INIT_EXTRA_FIELDS (&ce_info
);
2173 if (find_if_block (&ce_info
))
2176 if (HAVE_trap
&& HAVE_conditional_trap
2177 && find_cond_trap (test_bb
, then_edge
, else_edge
))
2181 && (! HAVE_conditional_execution
|| reload_completed
))
2183 if (find_if_case_1 (test_bb
, then_edge
, else_edge
))
2185 if (find_if_case_2 (test_bb
, then_edge
, else_edge
))
2193 fprintf (rtl_dump_file
, "Conversion succeeded on pass %d.\n", pass
);
2194 return ce_info
.test_bb
;
2197 /* Return true if a block has two edges, one of which falls through to the next
2198 block, and the other jumps to a specific block, so that we can tell if the
2199 block is part of an && test or an || test. Returns either -1 or the number
2200 of non-note, non-jump, non-USE/CLOBBER insns in the block. */
2203 block_jumps_and_fallthru_p (basic_block cur_bb
, basic_block target_bb
)
2206 int fallthru_p
= FALSE
;
2212 if (!cur_bb
|| !target_bb
)
2215 /* If no edges, obviously it doesn't jump or fallthru. */
2216 if (cur_bb
->succ
== NULL_EDGE
)
2219 for (cur_edge
= cur_bb
->succ
;
2220 cur_edge
!= NULL_EDGE
;
2221 cur_edge
= cur_edge
->succ_next
)
2223 if (cur_edge
->flags
& EDGE_COMPLEX
)
2224 /* Anything complex isn't what we want. */
2227 else if (cur_edge
->flags
& EDGE_FALLTHRU
)
2230 else if (cur_edge
->dest
== target_bb
)
2237 if ((jump_p
& fallthru_p
) == 0)
2240 /* Don't allow calls in the block, since this is used to group && and ||
2241 together for conditional execution support. ??? we should support
2242 conditional execution support across calls for IA-64 some day, but
2243 for now it makes the code simpler. */
2245 insn
= cur_bb
->head
;
2247 while (insn
!= NULL_RTX
)
2249 if (GET_CODE (insn
) == CALL_INSN
)
2253 && GET_CODE (insn
) != JUMP_INSN
2254 && GET_CODE (PATTERN (insn
)) != USE
2255 && GET_CODE (PATTERN (insn
)) != CLOBBER
)
2261 insn
= NEXT_INSN (insn
);
2267 /* Determine if a given basic block heads a simple IF-THEN or IF-THEN-ELSE
2268 block. If so, we'll try to convert the insns to not require the branch.
2269 Return TRUE if we were successful at converting the block. */
2272 find_if_block (struct ce_if_block
* ce_info
)
2274 basic_block test_bb
= ce_info
->test_bb
;
2275 basic_block then_bb
= ce_info
->then_bb
;
2276 basic_block else_bb
= ce_info
->else_bb
;
2277 basic_block join_bb
= NULL_BLOCK
;
2278 edge then_succ
= then_bb
->succ
;
2279 edge else_succ
= else_bb
->succ
;
2280 int then_predecessors
;
2281 int else_predecessors
;
2285 ce_info
->last_test_bb
= test_bb
;
2287 /* Discover if any fall through predecessors of the current test basic block
2288 were && tests (which jump to the else block) or || tests (which jump to
2290 if (HAVE_conditional_execution
&& reload_completed
2291 && test_bb
->pred
!= NULL_EDGE
2292 && test_bb
->pred
->pred_next
== NULL_EDGE
2293 && test_bb
->pred
->flags
== EDGE_FALLTHRU
)
2295 basic_block bb
= test_bb
->pred
->src
;
2296 basic_block target_bb
;
2297 int max_insns
= MAX_CONDITIONAL_EXECUTE
;
2300 /* Determine if the preceding block is an && or || block. */
2301 if ((n_insns
= block_jumps_and_fallthru_p (bb
, else_bb
)) >= 0)
2303 ce_info
->and_and_p
= TRUE
;
2304 target_bb
= else_bb
;
2306 else if ((n_insns
= block_jumps_and_fallthru_p (bb
, then_bb
)) >= 0)
2308 ce_info
->and_and_p
= FALSE
;
2309 target_bb
= then_bb
;
2312 target_bb
= NULL_BLOCK
;
2314 if (target_bb
&& n_insns
<= max_insns
)
2316 int total_insns
= 0;
2319 ce_info
->last_test_bb
= test_bb
;
2321 /* Found at least one && or || block, look for more. */
2324 ce_info
->test_bb
= test_bb
= bb
;
2325 total_insns
+= n_insns
;
2328 if (bb
->pred
== NULL_EDGE
|| bb
->pred
->pred_next
!= NULL_EDGE
)
2332 n_insns
= block_jumps_and_fallthru_p (bb
, target_bb
);
2334 while (n_insns
>= 0 && (total_insns
+ n_insns
) <= max_insns
);
2336 ce_info
->num_multiple_test_blocks
= blocks
;
2337 ce_info
->num_multiple_test_insns
= total_insns
;
2339 if (ce_info
->and_and_p
)
2340 ce_info
->num_and_and_blocks
= blocks
;
2342 ce_info
->num_or_or_blocks
= blocks
;
2346 /* Count the number of edges the THEN and ELSE blocks have. */
2347 then_predecessors
= 0;
2348 for (cur_edge
= then_bb
->pred
;
2349 cur_edge
!= NULL_EDGE
;
2350 cur_edge
= cur_edge
->pred_next
)
2352 then_predecessors
++;
2353 if (cur_edge
->flags
& EDGE_COMPLEX
)
2357 else_predecessors
= 0;
2358 for (cur_edge
= else_bb
->pred
;
2359 cur_edge
!= NULL_EDGE
;
2360 cur_edge
= cur_edge
->pred_next
)
2362 else_predecessors
++;
2363 if (cur_edge
->flags
& EDGE_COMPLEX
)
2367 /* The THEN block of an IF-THEN combo must have exactly one predecessor,
2368 other than any || blocks which jump to the THEN block. */
2369 if ((then_predecessors
- ce_info
->num_or_or_blocks
) != 1)
2372 /* The THEN block of an IF-THEN combo must have zero or one successors. */
2373 if (then_succ
!= NULL_EDGE
2374 && (then_succ
->succ_next
!= NULL_EDGE
2375 || (then_succ
->flags
& EDGE_COMPLEX
)
2376 || (flow2_completed
&& tablejump_p (then_bb
->end
, NULL
, NULL
))))
2379 /* If the THEN block has no successors, conditional execution can still
2380 make a conditional call. Don't do this unless the ELSE block has
2381 only one incoming edge -- the CFG manipulation is too ugly otherwise.
2382 Check for the last insn of the THEN block being an indirect jump, which
2383 is listed as not having any successors, but confuses the rest of the CE
2384 code processing. ??? we should fix this in the future. */
2385 if (then_succ
== NULL
)
2387 if (else_bb
->pred
->pred_next
== NULL_EDGE
)
2389 rtx last_insn
= then_bb
->end
;
2392 && GET_CODE (last_insn
) == NOTE
2393 && last_insn
!= then_bb
->head
)
2394 last_insn
= PREV_INSN (last_insn
);
2397 && GET_CODE (last_insn
) == JUMP_INSN
2398 && ! simplejump_p (last_insn
))
2402 else_bb
= NULL_BLOCK
;
2408 /* If the THEN block's successor is the other edge out of the TEST block,
2409 then we have an IF-THEN combo without an ELSE. */
2410 else if (then_succ
->dest
== else_bb
)
2413 else_bb
= NULL_BLOCK
;
2416 /* If the THEN and ELSE block meet in a subsequent block, and the ELSE
2417 has exactly one predecessor and one successor, and the outgoing edge
2418 is not complex, then we have an IF-THEN-ELSE combo. */
2419 else if (else_succ
!= NULL_EDGE
2420 && then_succ
->dest
== else_succ
->dest
2421 && else_bb
->pred
->pred_next
== NULL_EDGE
2422 && else_succ
->succ_next
== NULL_EDGE
2423 && ! (else_succ
->flags
& EDGE_COMPLEX
)
2424 && ! (flow2_completed
&& tablejump_p (else_bb
->end
, NULL
, NULL
)))
2425 join_bb
= else_succ
->dest
;
2427 /* Otherwise it is not an IF-THEN or IF-THEN-ELSE combination. */
2431 num_possible_if_blocks
++;
2435 fprintf (rtl_dump_file
, "\nIF-THEN%s block found, pass %d, start block %d [insn %d], then %d [%d]",
2436 (else_bb
) ? "-ELSE" : "",
2438 test_bb
->index
, (test_bb
->head
) ? (int)INSN_UID (test_bb
->head
) : -1,
2439 then_bb
->index
, (then_bb
->head
) ? (int)INSN_UID (then_bb
->head
) : -1);
2442 fprintf (rtl_dump_file
, ", else %d [%d]",
2443 else_bb
->index
, (else_bb
->head
) ? (int)INSN_UID (else_bb
->head
) : -1);
2445 fprintf (rtl_dump_file
, ", join %d [%d]",
2446 join_bb
->index
, (join_bb
->head
) ? (int)INSN_UID (join_bb
->head
) : -1);
2448 if (ce_info
->num_multiple_test_blocks
> 0)
2449 fprintf (rtl_dump_file
, ", %d %s block%s last test %d [%d]",
2450 ce_info
->num_multiple_test_blocks
,
2451 (ce_info
->and_and_p
) ? "&&" : "||",
2452 (ce_info
->num_multiple_test_blocks
== 1) ? "" : "s",
2453 ce_info
->last_test_bb
->index
,
2454 ((ce_info
->last_test_bb
->head
)
2455 ? (int)INSN_UID (ce_info
->last_test_bb
->head
)
2458 fputc ('\n', rtl_dump_file
);
2461 /* Make sure IF, THEN, and ELSE, blocks are adjacent. Actually, we get the
2462 first condition for free, since we've already asserted that there's a
2463 fallthru edge from IF to THEN. Likewise for the && and || blocks, since
2464 we checked the FALLTHRU flag, those are already adjacent to the last IF
2466 /* ??? As an enhancement, move the ELSE block. Have to deal with
2467 BLOCK notes, if by no other means than aborting the merge if they
2468 exist. Sticky enough I don't want to think about it now. */
2470 if (else_bb
&& (next
= next
->next_bb
) != else_bb
)
2472 if ((next
= next
->next_bb
) != join_bb
&& join_bb
!= EXIT_BLOCK_PTR
)
2480 /* Do the real work. */
2481 ce_info
->else_bb
= else_bb
;
2482 ce_info
->join_bb
= join_bb
;
2484 return process_if_block (ce_info
);
2487 /* Convert a branch over a trap, or a branch
2488 to a trap, into a conditional trap. */
2491 find_cond_trap (basic_block test_bb
, edge then_edge
, edge else_edge
)
2493 basic_block then_bb
= then_edge
->dest
;
2494 basic_block else_bb
= else_edge
->dest
;
2495 basic_block other_bb
, trap_bb
;
2496 rtx trap
, jump
, cond
, cond_earliest
, seq
;
2499 /* Locate the block with the trap instruction. */
2500 /* ??? While we look for no successors, we really ought to allow
2501 EH successors. Need to fix merge_if_block for that to work. */
2502 if ((trap
= block_has_only_trap (then_bb
)) != NULL
)
2503 trap_bb
= then_bb
, other_bb
= else_bb
;
2504 else if ((trap
= block_has_only_trap (else_bb
)) != NULL
)
2505 trap_bb
= else_bb
, other_bb
= then_bb
;
2511 fprintf (rtl_dump_file
, "\nTRAP-IF block found, start %d, trap %d\n",
2512 test_bb
->index
, trap_bb
->index
);
2515 /* If this is not a standard conditional jump, we can't parse it. */
2516 jump
= test_bb
->end
;
2517 cond
= noce_get_condition (jump
, &cond_earliest
);
2521 /* If the conditional jump is more than just a conditional jump, then
2522 we can not do if-conversion on this block. */
2523 if (! onlyjump_p (jump
))
2526 /* We must be comparing objects whose modes imply the size. */
2527 if (GET_MODE (XEXP (cond
, 0)) == BLKmode
)
2530 /* Reverse the comparison code, if necessary. */
2531 code
= GET_CODE (cond
);
2532 if (then_bb
== trap_bb
)
2534 code
= reversed_comparison_code (cond
, jump
);
2535 if (code
== UNKNOWN
)
2539 /* Attempt to generate the conditional trap. */
2540 seq
= gen_cond_trap (code
, XEXP (cond
, 0), XEXP (cond
, 1),
2541 TRAP_CODE (PATTERN (trap
)));
2547 /* Emit the new insns before cond_earliest. */
2548 emit_insn_before_setloc (seq
, cond_earliest
, INSN_LOCATOR (trap
));
2550 /* Delete the trap block if possible. */
2551 remove_edge (trap_bb
== then_bb
? then_edge
: else_edge
);
2552 if (trap_bb
->pred
== NULL
)
2554 if (post_dominators
)
2555 delete_from_dominance_info (post_dominators
, trap_bb
);
2556 delete_block (trap_bb
);
2559 /* If the non-trap block and the test are now adjacent, merge them.
2560 Otherwise we must insert a direct branch. */
2561 if (test_bb
->next_bb
== other_bb
)
2563 struct ce_if_block new_ce_info
;
2565 memset (&new_ce_info
, '\0', sizeof (new_ce_info
));
2566 new_ce_info
.test_bb
= test_bb
;
2567 new_ce_info
.then_bb
= NULL
;
2568 new_ce_info
.else_bb
= NULL
;
2569 new_ce_info
.join_bb
= other_bb
;
2570 merge_if_block (&new_ce_info
);
2576 lab
= JUMP_LABEL (jump
);
2577 newjump
= emit_jump_insn_after (gen_jump (lab
), jump
);
2578 LABEL_NUSES (lab
) += 1;
2579 JUMP_LABEL (newjump
) = lab
;
2580 emit_barrier_after (newjump
);
2588 /* Subroutine of find_cond_trap: if BB contains only a trap insn,
2592 block_has_only_trap (basic_block bb
)
2596 /* We're not the exit block. */
2597 if (bb
== EXIT_BLOCK_PTR
)
2600 /* The block must have no successors. */
2604 /* The only instruction in the THEN block must be the trap. */
2605 trap
= first_active_insn (bb
);
2606 if (! (trap
== bb
->end
2607 && GET_CODE (PATTERN (trap
)) == TRAP_IF
2608 && TRAP_CONDITION (PATTERN (trap
)) == const_true_rtx
))
2614 /* Look for IF-THEN-ELSE cases in which one of THEN or ELSE is
2615 transformable, but not necessarily the other. There need be no
2618 Return TRUE if we were successful at converting the block.
2620 Cases we'd like to look at:
2623 if (test) goto over; // x not live
2631 if (! test) goto label;
2634 if (test) goto E; // x not live
2648 (3) // This one's really only interesting for targets that can do
2649 // multiway branching, e.g. IA-64 BBB bundles. For other targets
2650 // it results in multiple branches on a cache line, which often
2651 // does not sit well with predictors.
2653 if (test1) goto E; // predicted not taken
2669 (A) Don't do (2) if the branch is predicted against the block we're
2670 eliminating. Do it anyway if we can eliminate a branch; this requires
2671 that the sole successor of the eliminated block postdominate the other
2674 (B) With CE, on (3) we can steal from both sides of the if, creating
2683 Again, this is most useful if J postdominates.
2685 (C) CE substitutes for helpful life information.
2687 (D) These heuristics need a lot of work. */
2689 /* Tests for case 1 above. */
2692 find_if_case_1 (basic_block test_bb
, edge then_edge
, edge else_edge
)
2694 basic_block then_bb
= then_edge
->dest
;
2695 basic_block else_bb
= else_edge
->dest
, new_bb
;
2696 edge then_succ
= then_bb
->succ
;
2699 /* THEN has one successor. */
2700 if (!then_succ
|| then_succ
->succ_next
!= NULL
)
2703 /* THEN does not fall through, but is not strange either. */
2704 if (then_succ
->flags
& (EDGE_COMPLEX
| EDGE_FALLTHRU
))
2707 /* THEN has one predecessor. */
2708 if (then_bb
->pred
->pred_next
!= NULL
)
2711 /* THEN must do something. */
2712 if (forwarder_block_p (then_bb
))
2715 num_possible_if_blocks
++;
2717 fprintf (rtl_dump_file
,
2718 "\nIF-CASE-1 found, start %d, then %d\n",
2719 test_bb
->index
, then_bb
->index
);
2721 /* THEN is small. */
2722 if (count_bb_insns (then_bb
) > BRANCH_COST
)
2725 /* Registers set are dead, or are predicable. */
2726 if (! dead_or_predicable (test_bb
, then_bb
, else_bb
,
2727 then_bb
->succ
->dest
, 1))
2730 /* Conversion went ok, including moving the insns and fixing up the
2731 jump. Adjust the CFG to match. */
2733 bitmap_operation (test_bb
->global_live_at_end
,
2734 else_bb
->global_live_at_start
,
2735 then_bb
->global_live_at_end
, BITMAP_IOR
);
2737 new_bb
= redirect_edge_and_branch_force (FALLTHRU_EDGE (test_bb
), else_bb
);
2738 then_bb_index
= then_bb
->index
;
2739 if (post_dominators
)
2740 delete_from_dominance_info (post_dominators
, then_bb
);
2741 delete_block (then_bb
);
2743 /* Make rest of code believe that the newly created block is the THEN_BB
2744 block we removed. */
2747 new_bb
->index
= then_bb_index
;
2748 BASIC_BLOCK (then_bb_index
) = new_bb
;
2749 if (post_dominators
)
2750 add_to_dominance_info (post_dominators
, new_bb
);
2752 /* We've possibly created jump to next insn, cleanup_cfg will solve that
2756 num_updated_if_blocks
++;
2761 /* Test for case 2 above. */
2764 find_if_case_2 (basic_block test_bb
, edge then_edge
, edge else_edge
)
2766 basic_block then_bb
= then_edge
->dest
;
2767 basic_block else_bb
= else_edge
->dest
;
2768 edge else_succ
= else_bb
->succ
;
2771 /* ELSE has one successor. */
2772 if (!else_succ
|| else_succ
->succ_next
!= NULL
)
2775 /* ELSE outgoing edge is not complex. */
2776 if (else_succ
->flags
& EDGE_COMPLEX
)
2779 /* ELSE has one predecessor. */
2780 if (else_bb
->pred
->pred_next
!= NULL
)
2783 /* THEN is not EXIT. */
2784 if (then_bb
->index
< 0)
2787 /* ELSE is predicted or SUCC(ELSE) postdominates THEN. */
2788 note
= find_reg_note (test_bb
->end
, REG_BR_PROB
, NULL_RTX
);
2789 if (note
&& INTVAL (XEXP (note
, 0)) >= REG_BR_PROB_BASE
/ 2)
2791 else if (else_succ
->dest
->index
< 0
2792 || dominated_by_p (post_dominators
, then_bb
,
2798 num_possible_if_blocks
++;
2800 fprintf (rtl_dump_file
,
2801 "\nIF-CASE-2 found, start %d, else %d\n",
2802 test_bb
->index
, else_bb
->index
);
2804 /* ELSE is small. */
2805 if (count_bb_insns (else_bb
) > BRANCH_COST
)
2808 /* Registers set are dead, or are predicable. */
2809 if (! dead_or_predicable (test_bb
, else_bb
, then_bb
, else_succ
->dest
, 0))
2812 /* Conversion went ok, including moving the insns and fixing up the
2813 jump. Adjust the CFG to match. */
2815 bitmap_operation (test_bb
->global_live_at_end
,
2816 then_bb
->global_live_at_start
,
2817 else_bb
->global_live_at_end
, BITMAP_IOR
);
2819 if (post_dominators
)
2820 delete_from_dominance_info (post_dominators
, else_bb
);
2821 delete_block (else_bb
);
2824 num_updated_if_blocks
++;
2826 /* ??? We may now fallthru from one of THEN's successors into a join
2827 block. Rerun cleanup_cfg? Examine things manually? Wait? */
2832 /* A subroutine of dead_or_predicable called through for_each_rtx.
2833 Return 1 if a memory is found. */
2836 find_memory (rtx
*px
, void *data ATTRIBUTE_UNUSED
)
2838 return GET_CODE (*px
) == MEM
;
2841 /* Used by the code above to perform the actual rtl transformations.
2842 Return TRUE if successful.
2844 TEST_BB is the block containing the conditional branch. MERGE_BB
2845 is the block containing the code to manipulate. NEW_DEST is the
2846 label TEST_BB should be branching to after the conversion.
2847 REVERSEP is true if the sense of the branch should be reversed. */
2850 dead_or_predicable (basic_block test_bb
, basic_block merge_bb
,
2851 basic_block other_bb
, basic_block new_dest
, int reversep
)
2853 rtx head
, end
, jump
, earliest
, old_dest
, new_label
= NULL_RTX
;
2855 jump
= test_bb
->end
;
2857 /* Find the extent of the real code in the merge block. */
2858 head
= merge_bb
->head
;
2859 end
= merge_bb
->end
;
2861 if (GET_CODE (head
) == CODE_LABEL
)
2862 head
= NEXT_INSN (head
);
2863 if (GET_CODE (head
) == NOTE
)
2867 head
= end
= NULL_RTX
;
2870 head
= NEXT_INSN (head
);
2873 if (GET_CODE (end
) == JUMP_INSN
)
2877 head
= end
= NULL_RTX
;
2880 end
= PREV_INSN (end
);
2883 /* Disable handling dead code by conditional execution if the machine needs
2884 to do anything funny with the tests, etc. */
2885 #ifndef IFCVT_MODIFY_TESTS
2886 if (HAVE_conditional_execution
)
2888 /* In the conditional execution case, we have things easy. We know
2889 the condition is reversible. We don't have to check life info,
2890 becase we're going to conditionally execute the code anyway.
2891 All that's left is making sure the insns involved can actually
2896 cond
= cond_exec_get_condition (jump
);
2900 prob_val
= find_reg_note (jump
, REG_BR_PROB
, NULL_RTX
);
2902 prob_val
= XEXP (prob_val
, 0);
2906 enum rtx_code rev
= reversed_comparison_code (cond
, jump
);
2909 cond
= gen_rtx_fmt_ee (rev
, GET_MODE (cond
), XEXP (cond
, 0),
2912 prob_val
= GEN_INT (REG_BR_PROB_BASE
- INTVAL (prob_val
));
2915 if (! cond_exec_process_insns ((ce_if_block_t
*)0, head
, end
, cond
,
2924 /* In the non-conditional execution case, we have to verify that there
2925 are no trapping operations, no calls, no references to memory, and
2926 that any registers modified are dead at the branch site. */
2928 rtx insn
, cond
, prev
;
2929 regset_head merge_set_head
, tmp_head
, test_live_head
, test_set_head
;
2930 regset merge_set
, tmp
, test_live
, test_set
;
2931 struct propagate_block_info
*pbi
;
2934 /* Check for no calls or trapping operations. */
2935 for (insn
= head
; ; insn
= NEXT_INSN (insn
))
2937 if (GET_CODE (insn
) == CALL_INSN
)
2941 if (may_trap_p (PATTERN (insn
)))
2944 /* ??? Even non-trapping memories such as stack frame
2945 references must be avoided. For stores, we collect
2946 no lifetime info; for reads, we'd have to assert
2947 true_dependence false against every store in the
2949 if (for_each_rtx (&PATTERN (insn
), find_memory
, NULL
))
2956 if (! any_condjump_p (jump
))
2959 /* Find the extent of the conditional. */
2960 cond
= noce_get_condition (jump
, &earliest
);
2965 MERGE_SET = set of registers set in MERGE_BB
2966 TEST_LIVE = set of registers live at EARLIEST
2967 TEST_SET = set of registers set between EARLIEST and the
2968 end of the block. */
2970 tmp
= INITIALIZE_REG_SET (tmp_head
);
2971 merge_set
= INITIALIZE_REG_SET (merge_set_head
);
2972 test_live
= INITIALIZE_REG_SET (test_live_head
);
2973 test_set
= INITIALIZE_REG_SET (test_set_head
);
2975 /* ??? bb->local_set is only valid during calculate_global_regs_live,
2976 so we must recompute usage for MERGE_BB. Not so bad, I suppose,
2977 since we've already asserted that MERGE_BB is small. */
2978 propagate_block (merge_bb
, tmp
, merge_set
, merge_set
, 0);
2980 /* For small register class machines, don't lengthen lifetimes of
2981 hard registers before reload. */
2982 if (SMALL_REGISTER_CLASSES
&& ! reload_completed
)
2984 EXECUTE_IF_SET_IN_BITMAP
2987 if (i
< FIRST_PSEUDO_REGISTER
2989 && ! global_regs
[i
])
2994 /* For TEST, we're interested in a range of insns, not a whole block.
2995 Moreover, we're interested in the insns live from OTHER_BB. */
2997 COPY_REG_SET (test_live
, other_bb
->global_live_at_start
);
2998 pbi
= init_propagate_block_info (test_bb
, test_live
, test_set
, test_set
,
3001 for (insn
= jump
; ; insn
= prev
)
3003 prev
= propagate_one_insn (pbi
, insn
);
3004 if (insn
== earliest
)
3008 free_propagate_block_info (pbi
);
3010 /* We can perform the transformation if
3011 MERGE_SET & (TEST_SET | TEST_LIVE)
3013 TEST_SET & merge_bb->global_live_at_start
3016 bitmap_operation (tmp
, test_set
, test_live
, BITMAP_IOR
);
3017 bitmap_operation (tmp
, tmp
, merge_set
, BITMAP_AND
);
3018 EXECUTE_IF_SET_IN_BITMAP(tmp
, 0, i
, fail
= 1);
3020 bitmap_operation (tmp
, test_set
, merge_bb
->global_live_at_start
,
3022 EXECUTE_IF_SET_IN_BITMAP(tmp
, 0, i
, fail
= 1);
3025 FREE_REG_SET (merge_set
);
3026 FREE_REG_SET (test_live
);
3027 FREE_REG_SET (test_set
);
3034 /* We don't want to use normal invert_jump or redirect_jump because
3035 we don't want to delete_insn called. Also, we want to do our own
3036 change group management. */
3038 old_dest
= JUMP_LABEL (jump
);
3039 if (other_bb
!= new_dest
)
3041 new_label
= block_label (new_dest
);
3043 ? ! invert_jump_1 (jump
, new_label
)
3044 : ! redirect_jump_1 (jump
, new_label
))
3048 if (! apply_change_group ())
3051 if (other_bb
!= new_dest
)
3054 LABEL_NUSES (old_dest
) -= 1;
3056 LABEL_NUSES (new_label
) += 1;
3057 JUMP_LABEL (jump
) = new_label
;
3059 invert_br_probabilities (jump
);
3061 redirect_edge_succ (BRANCH_EDGE (test_bb
), new_dest
);
3064 gcov_type count
, probability
;
3065 count
= BRANCH_EDGE (test_bb
)->count
;
3066 BRANCH_EDGE (test_bb
)->count
= FALLTHRU_EDGE (test_bb
)->count
;
3067 FALLTHRU_EDGE (test_bb
)->count
= count
;
3068 probability
= BRANCH_EDGE (test_bb
)->probability
;
3069 BRANCH_EDGE (test_bb
)->probability
3070 = FALLTHRU_EDGE (test_bb
)->probability
;
3071 FALLTHRU_EDGE (test_bb
)->probability
= probability
;
3072 update_br_prob_note (test_bb
);
3076 /* Move the insns out of MERGE_BB to before the branch. */
3079 if (end
== merge_bb
->end
)
3080 merge_bb
->end
= PREV_INSN (head
);
3082 if (squeeze_notes (&head
, &end
))
3085 reorder_insns (head
, end
, PREV_INSN (earliest
));
3088 /* Remove the jump and edge if we can. */
3089 if (other_bb
== new_dest
)
3092 remove_edge (BRANCH_EDGE (test_bb
));
3093 /* ??? Can't merge blocks here, as then_bb is still in use.
3094 At minimum, the merge will get done just before bb-reorder. */
3104 /* Main entry point for all if-conversion. */
3107 if_convert (int x_life_data_ok
)
3112 num_possible_if_blocks
= 0;
3113 num_updated_if_blocks
= 0;
3114 num_true_changes
= 0;
3115 life_data_ok
= (x_life_data_ok
!= 0);
3117 if (! (* targetm
.cannot_modify_jumps_p
) ())
3118 mark_loop_exit_edges ();
3120 /* Free up basic_block_for_insn so that we don't have to keep it
3121 up to date, either here or in merge_blocks. */
3122 free_basic_block_vars (1);
3124 /* Compute postdominators if we think we'll use them. */
3125 post_dominators
= NULL
;
3126 if (HAVE_conditional_execution
|| life_data_ok
)
3128 post_dominators
= calculate_dominance_info (CDI_POST_DOMINATORS
);
3133 /* Go through each of the basic blocks looking for things to convert. If we
3134 have conditional execution, we make multiple passes to allow us to handle
3135 IF-THEN{-ELSE} blocks within other IF-THEN{-ELSE} blocks. */
3139 cond_exec_changed_p
= FALSE
;
3142 #ifdef IFCVT_MULTIPLE_DUMPS
3143 if (rtl_dump_file
&& pass
> 1)
3144 fprintf (rtl_dump_file
, "\n\n========== Pass %d ==========\n", pass
);
3150 while ((new_bb
= find_if_header (bb
, pass
)))
3154 #ifdef IFCVT_MULTIPLE_DUMPS
3155 if (rtl_dump_file
&& cond_exec_changed_p
)
3156 print_rtl_with_bb (rtl_dump_file
, get_insns ());
3159 while (cond_exec_changed_p
);
3161 #ifdef IFCVT_MULTIPLE_DUMPS
3163 fprintf (rtl_dump_file
, "\n\n========== no more changes\n");
3166 if (post_dominators
)
3167 free_dominance_info (post_dominators
);
3170 fflush (rtl_dump_file
);
3172 clear_aux_for_blocks ();
3174 /* Rebuild life info for basic blocks that require it. */
3175 if (num_true_changes
&& life_data_ok
)
3177 /* If we allocated new pseudos, we must resize the array for sched1. */
3178 if (max_regno
< max_reg_num ())
3180 max_regno
= max_reg_num ();
3181 allocate_reg_info (max_regno
, FALSE
, FALSE
);
3183 update_life_info_in_dirty_blocks (UPDATE_LIFE_GLOBAL_RM_NOTES
,
3184 PROP_DEATH_NOTES
| PROP_SCAN_DEAD_CODE
3185 | PROP_KILL_DEAD_CODE
);
3188 /* Write the final stats. */
3189 if (rtl_dump_file
&& num_possible_if_blocks
> 0)
3191 fprintf (rtl_dump_file
,
3192 "\n%d possible IF blocks searched.\n",
3193 num_possible_if_blocks
);
3194 fprintf (rtl_dump_file
,
3195 "%d IF blocks converted.\n",
3196 num_updated_if_blocks
);
3197 fprintf (rtl_dump_file
,
3198 "%d true changes made.\n\n\n",
3202 #ifdef ENABLE_CHECKING
3203 verify_flow_info ();