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 basic blocks that were removed. */
79 static int num_removed_blocks
;
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 ()
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 /* Should be no `else' case to worry about. */
888 && if_info
->b
== if_info
->x
889 && GET_CODE (if_info
->a
) == PLUS
890 && rtx_equal_p (XEXP (if_info
->a
, 0), if_info
->x
)
891 && (reversed_comparison_code (if_info
->cond
, if_info
->jump
)
894 rtx cond
= if_info
->cond
;
895 enum rtx_code code
= reversed_comparison_code (cond
, if_info
->jump
);
897 /* First try to use addcc pattern. */
898 if (general_operand (XEXP (cond
, 0), VOIDmode
)
899 && general_operand (XEXP (cond
, 1), VOIDmode
))
902 target
= emit_conditional_add (if_info
->x
, code
,
903 XEXP (cond
, 0), XEXP (cond
, 1),
905 if_info
->b
, XEXP (if_info
->a
, 1),
906 GET_MODE (if_info
->x
),
907 (code
== LTU
|| code
== GEU
908 || code
== LEU
|| code
== GTU
));
911 if (target
!= if_info
->x
)
912 noce_emit_move_insn (if_info
->x
, target
);
916 emit_insn_before_setloc (seq
, if_info
->jump
,
917 INSN_LOCATOR (if_info
->insn_a
));
923 /* If that fails, construct conditional increment or decrement using
926 && (XEXP (if_info
->a
, 1) == const1_rtx
927 || XEXP (if_info
->a
, 1) == constm1_rtx
))
930 if (STORE_FLAG_VALUE
== INTVAL (XEXP (if_info
->a
, 1)))
931 subtract
= 0, normalize
= 0;
932 else if (-STORE_FLAG_VALUE
== INTVAL (XEXP (if_info
->a
, 1)))
933 subtract
= 1, normalize
= 0;
935 subtract
= 0, normalize
= INTVAL (XEXP (if_info
->a
, 1));
938 target
= noce_emit_store_flag (if_info
,
939 gen_reg_rtx (GET_MODE (if_info
->x
)),
943 target
= expand_simple_binop (GET_MODE (if_info
->x
),
944 subtract
? MINUS
: PLUS
,
945 if_info
->x
, target
, if_info
->x
,
949 if (target
!= if_info
->x
)
950 noce_emit_move_insn (if_info
->x
, target
);
955 if (seq_contains_jump (seq
))
958 emit_insn_before_setloc (seq
, if_info
->jump
,
959 INSN_LOCATOR (if_info
->insn_a
));
970 /* Convert "if (test) x = 0;" to "x &= -(test == 0);" */
973 noce_try_store_flag_mask (struct noce_if_info
*if_info
)
981 || STORE_FLAG_VALUE
== -1)
982 && ((if_info
->a
== const0_rtx
983 && rtx_equal_p (if_info
->b
, if_info
->x
))
984 || ((reversep
= (reversed_comparison_code (if_info
->cond
,
987 && if_info
->b
== const0_rtx
988 && rtx_equal_p (if_info
->a
, if_info
->x
))))
991 target
= noce_emit_store_flag (if_info
,
992 gen_reg_rtx (GET_MODE (if_info
->x
)),
995 target
= expand_simple_binop (GET_MODE (if_info
->x
), AND
,
996 if_info
->x
, target
, if_info
->x
, 0,
1001 if (target
!= if_info
->x
)
1002 noce_emit_move_insn (if_info
->x
, target
);
1007 if (seq_contains_jump (seq
))
1010 emit_insn_before_setloc (seq
, if_info
->jump
,
1011 INSN_LOCATOR (if_info
->insn_a
));
1022 /* Helper function for noce_try_cmove and noce_try_cmove_arith. */
1025 noce_emit_cmove (struct noce_if_info
*if_info
, rtx x
, enum rtx_code code
,
1026 rtx cmp_a
, rtx cmp_b
, rtx vfalse
, rtx vtrue
)
1028 /* If earliest == jump, try to build the cmove insn directly.
1029 This is helpful when combine has created some complex condition
1030 (like for alpha's cmovlbs) that we can't hope to regenerate
1031 through the normal interface. */
1033 if (if_info
->cond_earliest
== if_info
->jump
)
1037 tmp
= gen_rtx_fmt_ee (code
, GET_MODE (if_info
->cond
), cmp_a
, cmp_b
);
1038 tmp
= gen_rtx_IF_THEN_ELSE (GET_MODE (x
), tmp
, vtrue
, vfalse
);
1039 tmp
= gen_rtx_SET (VOIDmode
, x
, tmp
);
1042 tmp
= emit_insn (tmp
);
1044 if (recog_memoized (tmp
) >= 0)
1056 /* Don't even try if the comparison operands are weird. */
1057 if (! general_operand (cmp_a
, GET_MODE (cmp_a
))
1058 || ! general_operand (cmp_b
, GET_MODE (cmp_b
)))
1061 #if HAVE_conditional_move
1062 return emit_conditional_move (x
, code
, cmp_a
, cmp_b
, VOIDmode
,
1063 vtrue
, vfalse
, GET_MODE (x
),
1064 (code
== LTU
|| code
== GEU
1065 || code
== LEU
|| code
== GTU
));
1067 /* We'll never get here, as noce_process_if_block doesn't call the
1068 functions involved. Ifdef code, however, should be discouraged
1069 because it leads to typos in the code not selected. However,
1070 emit_conditional_move won't exist either. */
1075 /* Try only simple constants and registers here. More complex cases
1076 are handled in noce_try_cmove_arith after noce_try_store_flag_arith
1077 has had a go at it. */
1080 noce_try_cmove (struct noce_if_info
*if_info
)
1085 if ((CONSTANT_P (if_info
->a
) || register_operand (if_info
->a
, VOIDmode
))
1086 && (CONSTANT_P (if_info
->b
) || register_operand (if_info
->b
, VOIDmode
)))
1090 code
= GET_CODE (if_info
->cond
);
1091 target
= noce_emit_cmove (if_info
, if_info
->x
, code
,
1092 XEXP (if_info
->cond
, 0),
1093 XEXP (if_info
->cond
, 1),
1094 if_info
->a
, if_info
->b
);
1098 if (target
!= if_info
->x
)
1099 noce_emit_move_insn (if_info
->x
, target
);
1103 emit_insn_before_setloc (seq
, if_info
->jump
,
1104 INSN_LOCATOR (if_info
->insn_a
));
1117 /* Try more complex cases involving conditional_move. */
1120 noce_try_cmove_arith (struct noce_if_info
*if_info
)
1130 /* A conditional move from two memory sources is equivalent to a
1131 conditional on their addresses followed by a load. Don't do this
1132 early because it'll screw alias analysis. Note that we've
1133 already checked for no side effects. */
1134 if (! no_new_pseudos
&& cse_not_expected
1135 && GET_CODE (a
) == MEM
&& GET_CODE (b
) == MEM
1136 && BRANCH_COST
>= 5)
1140 x
= gen_reg_rtx (Pmode
);
1144 /* ??? We could handle this if we knew that a load from A or B could
1145 not fault. This is also true if we've already loaded
1146 from the address along the path from ENTRY. */
1147 else if (may_trap_p (a
) || may_trap_p (b
))
1150 /* if (test) x = a + b; else x = c - d;
1157 code
= GET_CODE (if_info
->cond
);
1158 insn_a
= if_info
->insn_a
;
1159 insn_b
= if_info
->insn_b
;
1161 /* Possibly rearrange operands to make things come out more natural. */
1162 if (reversed_comparison_code (if_info
->cond
, if_info
->jump
) != UNKNOWN
)
1165 if (rtx_equal_p (b
, x
))
1167 else if (general_operand (b
, GET_MODE (b
)))
1172 code
= reversed_comparison_code (if_info
->cond
, if_info
->jump
);
1173 tmp
= a
, a
= b
, b
= tmp
;
1174 tmp
= insn_a
, insn_a
= insn_b
, insn_b
= tmp
;
1180 /* If either operand is complex, load it into a register first.
1181 The best way to do this is to copy the original insn. In this
1182 way we preserve any clobbers etc that the insn may have had.
1183 This is of course not possible in the IS_MEM case. */
1184 if (! general_operand (a
, GET_MODE (a
)))
1189 goto end_seq_and_fail
;
1193 tmp
= gen_reg_rtx (GET_MODE (a
));
1194 tmp
= emit_insn (gen_rtx_SET (VOIDmode
, tmp
, a
));
1197 goto end_seq_and_fail
;
1200 a
= gen_reg_rtx (GET_MODE (a
));
1201 tmp
= copy_rtx (insn_a
);
1202 set
= single_set (tmp
);
1204 tmp
= emit_insn (PATTERN (tmp
));
1206 if (recog_memoized (tmp
) < 0)
1207 goto end_seq_and_fail
;
1209 if (! general_operand (b
, GET_MODE (b
)))
1214 goto end_seq_and_fail
;
1218 tmp
= gen_reg_rtx (GET_MODE (b
));
1219 tmp
= emit_insn (gen_rtx_SET (VOIDmode
, tmp
, b
));
1222 goto end_seq_and_fail
;
1225 b
= gen_reg_rtx (GET_MODE (b
));
1226 tmp
= copy_rtx (insn_b
);
1227 set
= single_set (tmp
);
1229 tmp
= emit_insn (PATTERN (tmp
));
1231 if (recog_memoized (tmp
) < 0)
1232 goto end_seq_and_fail
;
1235 target
= noce_emit_cmove (if_info
, x
, code
, XEXP (if_info
->cond
, 0),
1236 XEXP (if_info
->cond
, 1), a
, b
);
1239 goto end_seq_and_fail
;
1241 /* If we're handling a memory for above, emit the load now. */
1244 tmp
= gen_rtx_MEM (GET_MODE (if_info
->x
), target
);
1246 /* Copy over flags as appropriate. */
1247 if (MEM_VOLATILE_P (if_info
->a
) || MEM_VOLATILE_P (if_info
->b
))
1248 MEM_VOLATILE_P (tmp
) = 1;
1249 if (MEM_IN_STRUCT_P (if_info
->a
) && MEM_IN_STRUCT_P (if_info
->b
))
1250 MEM_IN_STRUCT_P (tmp
) = 1;
1251 if (MEM_SCALAR_P (if_info
->a
) && MEM_SCALAR_P (if_info
->b
))
1252 MEM_SCALAR_P (tmp
) = 1;
1253 if (MEM_ALIAS_SET (if_info
->a
) == MEM_ALIAS_SET (if_info
->b
))
1254 set_mem_alias_set (tmp
, MEM_ALIAS_SET (if_info
->a
));
1256 MIN (MEM_ALIGN (if_info
->a
), MEM_ALIGN (if_info
->b
)));
1258 noce_emit_move_insn (if_info
->x
, tmp
);
1260 else if (target
!= x
)
1261 noce_emit_move_insn (x
, target
);
1265 emit_insn_before_setloc (tmp
, if_info
->jump
, INSN_LOCATOR (if_info
->insn_a
));
1273 /* For most cases, the simplified condition we found is the best
1274 choice, but this is not the case for the min/max/abs transforms.
1275 For these we wish to know that it is A or B in the condition. */
1278 noce_get_alt_condition (struct noce_if_info
*if_info
, rtx target
,
1281 rtx cond
, set
, insn
;
1284 /* If target is already mentioned in the known condition, return it. */
1285 if (reg_mentioned_p (target
, if_info
->cond
))
1287 *earliest
= if_info
->cond_earliest
;
1288 return if_info
->cond
;
1291 set
= pc_set (if_info
->jump
);
1292 cond
= XEXP (SET_SRC (set
), 0);
1294 = GET_CODE (XEXP (SET_SRC (set
), 2)) == LABEL_REF
1295 && XEXP (XEXP (SET_SRC (set
), 2), 0) == JUMP_LABEL (if_info
->jump
);
1297 /* If we're looking for a constant, try to make the conditional
1298 have that constant in it. There are two reasons why it may
1299 not have the constant we want:
1301 1. GCC may have needed to put the constant in a register, because
1302 the target can't compare directly against that constant. For
1303 this case, we look for a SET immediately before the comparison
1304 that puts a constant in that register.
1306 2. GCC may have canonicalized the conditional, for example
1307 replacing "if x < 4" with "if x <= 3". We can undo that (or
1308 make equivalent types of changes) to get the constants we need
1309 if they're off by one in the right direction. */
1311 if (GET_CODE (target
) == CONST_INT
)
1313 enum rtx_code code
= GET_CODE (if_info
->cond
);
1314 rtx op_a
= XEXP (if_info
->cond
, 0);
1315 rtx op_b
= XEXP (if_info
->cond
, 1);
1318 /* First, look to see if we put a constant in a register. */
1319 prev_insn
= PREV_INSN (if_info
->cond_earliest
);
1321 && INSN_P (prev_insn
)
1322 && GET_CODE (PATTERN (prev_insn
)) == SET
)
1324 rtx src
= find_reg_equal_equiv_note (prev_insn
);
1326 src
= SET_SRC (PATTERN (prev_insn
));
1327 if (GET_CODE (src
) == CONST_INT
)
1329 if (rtx_equal_p (op_a
, SET_DEST (PATTERN (prev_insn
))))
1331 else if (rtx_equal_p (op_b
, SET_DEST (PATTERN (prev_insn
))))
1334 if (GET_CODE (op_a
) == CONST_INT
)
1339 code
= swap_condition (code
);
1344 /* Now, look to see if we can get the right constant by
1345 adjusting the conditional. */
1346 if (GET_CODE (op_b
) == CONST_INT
)
1348 HOST_WIDE_INT desired_val
= INTVAL (target
);
1349 HOST_WIDE_INT actual_val
= INTVAL (op_b
);
1354 if (actual_val
== desired_val
+ 1)
1357 op_b
= GEN_INT (desired_val
);
1361 if (actual_val
== desired_val
- 1)
1364 op_b
= GEN_INT (desired_val
);
1368 if (actual_val
== desired_val
- 1)
1371 op_b
= GEN_INT (desired_val
);
1375 if (actual_val
== desired_val
+ 1)
1378 op_b
= GEN_INT (desired_val
);
1386 /* If we made any changes, generate a new conditional that is
1387 equivalent to what we started with, but has the right
1389 if (code
!= GET_CODE (if_info
->cond
)
1390 || op_a
!= XEXP (if_info
->cond
, 0)
1391 || op_b
!= XEXP (if_info
->cond
, 1))
1393 cond
= gen_rtx_fmt_ee (code
, GET_MODE (cond
), op_a
, op_b
);
1394 *earliest
= if_info
->cond_earliest
;
1399 cond
= canonicalize_condition (if_info
->jump
, cond
, reverse
,
1401 if (! cond
|| ! reg_mentioned_p (target
, cond
))
1404 /* We almost certainly searched back to a different place.
1405 Need to re-verify correct lifetimes. */
1407 /* X may not be mentioned in the range (cond_earliest, jump]. */
1408 for (insn
= if_info
->jump
; insn
!= *earliest
; insn
= PREV_INSN (insn
))
1409 if (INSN_P (insn
) && reg_overlap_mentioned_p (if_info
->x
, PATTERN (insn
)))
1412 /* A and B may not be modified in the range [cond_earliest, jump). */
1413 for (insn
= *earliest
; insn
!= if_info
->jump
; insn
= NEXT_INSN (insn
))
1415 && (modified_in_p (if_info
->a
, insn
)
1416 || modified_in_p (if_info
->b
, insn
)))
1422 /* Convert "if (a < b) x = a; else x = b;" to "x = min(a, b);", etc. */
1425 noce_try_minmax (struct noce_if_info
*if_info
)
1427 rtx cond
, earliest
, target
, seq
;
1428 enum rtx_code code
, op
;
1431 /* ??? Can't guarantee that expand_binop won't create pseudos. */
1435 /* ??? Reject modes with NaNs or signed zeros since we don't know how
1436 they will be resolved with an SMIN/SMAX. It wouldn't be too hard
1437 to get the target to tell us... */
1438 if (HONOR_SIGNED_ZEROS (GET_MODE (if_info
->x
))
1439 || HONOR_NANS (GET_MODE (if_info
->x
)))
1442 cond
= noce_get_alt_condition (if_info
, if_info
->a
, &earliest
);
1446 /* Verify the condition is of the form we expect, and canonicalize
1447 the comparison code. */
1448 code
= GET_CODE (cond
);
1449 if (rtx_equal_p (XEXP (cond
, 0), if_info
->a
))
1451 if (! rtx_equal_p (XEXP (cond
, 1), if_info
->b
))
1454 else if (rtx_equal_p (XEXP (cond
, 1), if_info
->a
))
1456 if (! rtx_equal_p (XEXP (cond
, 0), if_info
->b
))
1458 code
= swap_condition (code
);
1463 /* Determine what sort of operation this is. Note that the code is for
1464 a taken branch, so the code->operation mapping appears backwards. */
1497 target
= expand_simple_binop (GET_MODE (if_info
->x
), op
,
1498 if_info
->a
, if_info
->b
,
1499 if_info
->x
, unsignedp
, OPTAB_WIDEN
);
1505 if (target
!= if_info
->x
)
1506 noce_emit_move_insn (if_info
->x
, target
);
1511 if (seq_contains_jump (seq
))
1514 emit_insn_before_setloc (seq
, if_info
->jump
, INSN_LOCATOR (if_info
->insn_a
));
1515 if_info
->cond
= cond
;
1516 if_info
->cond_earliest
= earliest
;
1521 /* Convert "if (a < 0) x = -a; else x = a;" to "x = abs(a);", etc. */
1524 noce_try_abs (struct noce_if_info
*if_info
)
1526 rtx cond
, earliest
, target
, seq
, a
, b
, c
;
1529 /* ??? Can't guarantee that expand_binop won't create pseudos. */
1533 /* Recognize A and B as constituting an ABS or NABS. */
1536 if (GET_CODE (a
) == NEG
&& rtx_equal_p (XEXP (a
, 0), b
))
1538 else if (GET_CODE (b
) == NEG
&& rtx_equal_p (XEXP (b
, 0), a
))
1540 c
= a
; a
= b
; b
= c
;
1546 cond
= noce_get_alt_condition (if_info
, b
, &earliest
);
1550 /* Verify the condition is of the form we expect. */
1551 if (rtx_equal_p (XEXP (cond
, 0), b
))
1553 else if (rtx_equal_p (XEXP (cond
, 1), b
))
1558 /* Verify that C is zero. Search backward through the block for
1559 a REG_EQUAL note if necessary. */
1562 rtx insn
, note
= NULL
;
1563 for (insn
= earliest
;
1564 insn
!= if_info
->test_bb
->head
;
1565 insn
= PREV_INSN (insn
))
1567 && ((note
= find_reg_note (insn
, REG_EQUAL
, c
))
1568 || (note
= find_reg_note (insn
, REG_EQUIV
, c
))))
1574 if (GET_CODE (c
) == MEM
1575 && GET_CODE (XEXP (c
, 0)) == SYMBOL_REF
1576 && CONSTANT_POOL_ADDRESS_P (XEXP (c
, 0)))
1577 c
= get_pool_constant (XEXP (c
, 0));
1579 /* Work around funny ideas get_condition has wrt canonicalization.
1580 Note that these rtx constants are known to be CONST_INT, and
1581 therefore imply integer comparisons. */
1582 if (c
== constm1_rtx
&& GET_CODE (cond
) == GT
)
1584 else if (c
== const1_rtx
&& GET_CODE (cond
) == LT
)
1586 else if (c
!= CONST0_RTX (GET_MODE (b
)))
1589 /* Determine what sort of operation this is. */
1590 switch (GET_CODE (cond
))
1609 target
= expand_abs_nojump (GET_MODE (if_info
->x
), b
, if_info
->x
, 1);
1611 /* ??? It's a quandry whether cmove would be better here, especially
1612 for integers. Perhaps combine will clean things up. */
1613 if (target
&& negate
)
1614 target
= expand_simple_unop (GET_MODE (target
), NEG
, target
, if_info
->x
, 0);
1622 if (target
!= if_info
->x
)
1623 noce_emit_move_insn (if_info
->x
, target
);
1628 if (seq_contains_jump (seq
))
1631 emit_insn_before_setloc (seq
, if_info
->jump
, INSN_LOCATOR (if_info
->insn_a
));
1632 if_info
->cond
= cond
;
1633 if_info
->cond_earliest
= earliest
;
1638 /* Similar to get_condition, only the resulting condition must be
1639 valid at JUMP, instead of at EARLIEST. */
1642 noce_get_condition (rtx jump
, rtx
*earliest
)
1644 rtx cond
, set
, tmp
, insn
;
1647 if (! any_condjump_p (jump
))
1650 set
= pc_set (jump
);
1652 /* If this branches to JUMP_LABEL when the condition is false,
1653 reverse the condition. */
1654 reverse
= (GET_CODE (XEXP (SET_SRC (set
), 2)) == LABEL_REF
1655 && XEXP (XEXP (SET_SRC (set
), 2), 0) == JUMP_LABEL (jump
));
1657 /* If the condition variable is a register and is MODE_INT, accept it. */
1659 cond
= XEXP (SET_SRC (set
), 0);
1660 tmp
= XEXP (cond
, 0);
1661 if (REG_P (tmp
) && GET_MODE_CLASS (GET_MODE (tmp
)) == MODE_INT
)
1666 cond
= gen_rtx_fmt_ee (reverse_condition (GET_CODE (cond
)),
1667 GET_MODE (cond
), tmp
, XEXP (cond
, 1));
1671 /* Otherwise, fall back on canonicalize_condition to do the dirty
1672 work of manipulating MODE_CC values and COMPARE rtx codes. */
1674 tmp
= canonicalize_condition (jump
, cond
, reverse
, earliest
, NULL_RTX
);
1678 /* We are going to insert code before JUMP, not before EARLIEST.
1679 We must therefore be certain that the given condition is valid
1680 at JUMP by virtue of not having been modified since. */
1681 for (insn
= *earliest
; insn
!= jump
; insn
= NEXT_INSN (insn
))
1682 if (INSN_P (insn
) && modified_in_p (tmp
, insn
))
1687 /* The condition was modified. See if we can get a partial result
1688 that doesn't follow all the reversals. Perhaps combine can fold
1689 them together later. */
1690 tmp
= XEXP (tmp
, 0);
1691 if (!REG_P (tmp
) || GET_MODE_CLASS (GET_MODE (tmp
)) != MODE_INT
)
1693 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
);
2017 num_removed_blocks
++;
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
);
2034 num_removed_blocks
++;
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
);
2045 num_removed_blocks
++;
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
);
2102 num_removed_blocks
++;
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
)));
2545 /* Emit the new insns before cond_earliest. */
2546 emit_insn_before_setloc (seq
, cond_earliest
, INSN_LOCATOR (trap
));
2548 /* Delete the trap block if possible. */
2549 remove_edge (trap_bb
== then_bb
? then_edge
: else_edge
);
2550 if (trap_bb
->pred
== NULL
)
2552 if (post_dominators
)
2553 delete_from_dominance_info (post_dominators
, trap_bb
);
2554 delete_block (trap_bb
);
2555 num_removed_blocks
++;
2558 /* If the non-trap block and the test are now adjacent, merge them.
2559 Otherwise we must insert a direct branch. */
2560 if (test_bb
->next_bb
== other_bb
)
2562 struct ce_if_block new_ce_info
;
2564 memset (&new_ce_info
, '\0', sizeof (new_ce_info
));
2565 new_ce_info
.test_bb
= test_bb
;
2566 new_ce_info
.then_bb
= NULL
;
2567 new_ce_info
.else_bb
= NULL
;
2568 new_ce_info
.join_bb
= other_bb
;
2569 merge_if_block (&new_ce_info
);
2575 lab
= JUMP_LABEL (jump
);
2576 newjump
= emit_jump_insn_after (gen_jump (lab
), jump
);
2577 LABEL_NUSES (lab
) += 1;
2578 JUMP_LABEL (newjump
) = lab
;
2579 emit_barrier_after (newjump
);
2587 /* Subroutine of find_cond_trap: if BB contains only a trap insn,
2591 block_has_only_trap (basic_block bb
)
2595 /* We're not the exit block. */
2596 if (bb
== EXIT_BLOCK_PTR
)
2599 /* The block must have no successors. */
2603 /* The only instruction in the THEN block must be the trap. */
2604 trap
= first_active_insn (bb
);
2605 if (! (trap
== bb
->end
2606 && GET_CODE (PATTERN (trap
)) == TRAP_IF
2607 && TRAP_CONDITION (PATTERN (trap
)) == const_true_rtx
))
2613 /* Look for IF-THEN-ELSE cases in which one of THEN or ELSE is
2614 transformable, but not necessarily the other. There need be no
2617 Return TRUE if we were successful at converting the block.
2619 Cases we'd like to look at:
2622 if (test) goto over; // x not live
2630 if (! test) goto label;
2633 if (test) goto E; // x not live
2647 (3) // This one's really only interesting for targets that can do
2648 // multiway branching, e.g. IA-64 BBB bundles. For other targets
2649 // it results in multiple branches on a cache line, which often
2650 // does not sit well with predictors.
2652 if (test1) goto E; // predicted not taken
2668 (A) Don't do (2) if the branch is predicted against the block we're
2669 eliminating. Do it anyway if we can eliminate a branch; this requires
2670 that the sole successor of the eliminated block postdominate the other
2673 (B) With CE, on (3) we can steal from both sides of the if, creating
2682 Again, this is most useful if J postdominates.
2684 (C) CE substitutes for helpful life information.
2686 (D) These heuristics need a lot of work. */
2688 /* Tests for case 1 above. */
2691 find_if_case_1 (basic_block test_bb
, edge then_edge
, edge else_edge
)
2693 basic_block then_bb
= then_edge
->dest
;
2694 basic_block else_bb
= else_edge
->dest
, new_bb
;
2695 edge then_succ
= then_bb
->succ
;
2698 /* THEN has one successor. */
2699 if (!then_succ
|| then_succ
->succ_next
!= NULL
)
2702 /* THEN does not fall through, but is not strange either. */
2703 if (then_succ
->flags
& (EDGE_COMPLEX
| EDGE_FALLTHRU
))
2706 /* THEN has one predecessor. */
2707 if (then_bb
->pred
->pred_next
!= NULL
)
2710 /* THEN must do something. */
2711 if (forwarder_block_p (then_bb
))
2714 num_possible_if_blocks
++;
2716 fprintf (rtl_dump_file
,
2717 "\nIF-CASE-1 found, start %d, then %d\n",
2718 test_bb
->index
, then_bb
->index
);
2720 /* THEN is small. */
2721 if (count_bb_insns (then_bb
) > BRANCH_COST
)
2724 /* Registers set are dead, or are predicable. */
2725 if (! dead_or_predicable (test_bb
, then_bb
, else_bb
,
2726 then_bb
->succ
->dest
, 1))
2729 /* Conversion went ok, including moving the insns and fixing up the
2730 jump. Adjust the CFG to match. */
2732 bitmap_operation (test_bb
->global_live_at_end
,
2733 else_bb
->global_live_at_start
,
2734 then_bb
->global_live_at_end
, BITMAP_IOR
);
2736 new_bb
= redirect_edge_and_branch_force (FALLTHRU_EDGE (test_bb
), else_bb
);
2737 then_bb_index
= then_bb
->index
;
2738 if (post_dominators
)
2739 delete_from_dominance_info (post_dominators
, then_bb
);
2740 delete_block (then_bb
);
2742 /* Make rest of code believe that the newly created block is the THEN_BB
2743 block we removed. */
2746 new_bb
->index
= then_bb_index
;
2747 BASIC_BLOCK (then_bb_index
) = new_bb
;
2748 if (post_dominators
)
2749 add_to_dominance_info (post_dominators
, new_bb
);
2751 /* We've possibly created jump to next insn, cleanup_cfg will solve that
2754 num_removed_blocks
++;
2755 num_updated_if_blocks
++;
2760 /* Test for case 2 above. */
2763 find_if_case_2 (basic_block test_bb
, edge then_edge
, edge else_edge
)
2765 basic_block then_bb
= then_edge
->dest
;
2766 basic_block else_bb
= else_edge
->dest
;
2767 edge else_succ
= else_bb
->succ
;
2770 /* ELSE has one successor. */
2771 if (!else_succ
|| else_succ
->succ_next
!= NULL
)
2774 /* ELSE outgoing edge is not complex. */
2775 if (else_succ
->flags
& EDGE_COMPLEX
)
2778 /* ELSE has one predecessor. */
2779 if (else_bb
->pred
->pred_next
!= NULL
)
2782 /* THEN is not EXIT. */
2783 if (then_bb
->index
< 0)
2786 /* ELSE is predicted or SUCC(ELSE) postdominates THEN. */
2787 note
= find_reg_note (test_bb
->end
, REG_BR_PROB
, NULL_RTX
);
2788 if (note
&& INTVAL (XEXP (note
, 0)) >= REG_BR_PROB_BASE
/ 2)
2790 else if (else_succ
->dest
->index
< 0
2791 || dominated_by_p (post_dominators
, then_bb
,
2797 num_possible_if_blocks
++;
2799 fprintf (rtl_dump_file
,
2800 "\nIF-CASE-2 found, start %d, else %d\n",
2801 test_bb
->index
, else_bb
->index
);
2803 /* ELSE is small. */
2804 if (count_bb_insns (else_bb
) > BRANCH_COST
)
2807 /* Registers set are dead, or are predicable. */
2808 if (! dead_or_predicable (test_bb
, else_bb
, then_bb
, else_succ
->dest
, 0))
2811 /* Conversion went ok, including moving the insns and fixing up the
2812 jump. Adjust the CFG to match. */
2814 bitmap_operation (test_bb
->global_live_at_end
,
2815 then_bb
->global_live_at_start
,
2816 else_bb
->global_live_at_end
, BITMAP_IOR
);
2818 if (post_dominators
)
2819 delete_from_dominance_info (post_dominators
, else_bb
);
2820 delete_block (else_bb
);
2822 num_removed_blocks
++;
2823 num_updated_if_blocks
++;
2825 /* ??? We may now fallthru from one of THEN's successors into a join
2826 block. Rerun cleanup_cfg? Examine things manually? Wait? */
2831 /* A subroutine of dead_or_predicable called through for_each_rtx.
2832 Return 1 if a memory is found. */
2835 find_memory (rtx
*px
, void *data ATTRIBUTE_UNUSED
)
2837 return GET_CODE (*px
) == MEM
;
2840 /* Used by the code above to perform the actual rtl transformations.
2841 Return TRUE if successful.
2843 TEST_BB is the block containing the conditional branch. MERGE_BB
2844 is the block containing the code to manipulate. NEW_DEST is the
2845 label TEST_BB should be branching to after the conversion.
2846 REVERSEP is true if the sense of the branch should be reversed. */
2849 dead_or_predicable (basic_block test_bb
, basic_block merge_bb
,
2850 basic_block other_bb
, basic_block new_dest
, int reversep
)
2852 rtx head
, end
, jump
, earliest
, old_dest
, new_label
= NULL_RTX
;
2854 jump
= test_bb
->end
;
2856 /* Find the extent of the real code in the merge block. */
2857 head
= merge_bb
->head
;
2858 end
= merge_bb
->end
;
2860 if (GET_CODE (head
) == CODE_LABEL
)
2861 head
= NEXT_INSN (head
);
2862 if (GET_CODE (head
) == NOTE
)
2866 head
= end
= NULL_RTX
;
2869 head
= NEXT_INSN (head
);
2872 if (GET_CODE (end
) == JUMP_INSN
)
2876 head
= end
= NULL_RTX
;
2879 end
= PREV_INSN (end
);
2882 /* Disable handling dead code by conditional execution if the machine needs
2883 to do anything funny with the tests, etc. */
2884 #ifndef IFCVT_MODIFY_TESTS
2885 if (HAVE_conditional_execution
)
2887 /* In the conditional execution case, we have things easy. We know
2888 the condition is reversible. We don't have to check life info,
2889 becase we're going to conditionally execute the code anyway.
2890 All that's left is making sure the insns involved can actually
2895 cond
= cond_exec_get_condition (jump
);
2899 prob_val
= find_reg_note (jump
, REG_BR_PROB
, NULL_RTX
);
2901 prob_val
= XEXP (prob_val
, 0);
2905 enum rtx_code rev
= reversed_comparison_code (cond
, jump
);
2908 cond
= gen_rtx_fmt_ee (rev
, GET_MODE (cond
), XEXP (cond
, 0),
2911 prob_val
= GEN_INT (REG_BR_PROB_BASE
- INTVAL (prob_val
));
2914 if (! cond_exec_process_insns ((ce_if_block_t
*)0, head
, end
, cond
,
2923 /* In the non-conditional execution case, we have to verify that there
2924 are no trapping operations, no calls, no references to memory, and
2925 that any registers modified are dead at the branch site. */
2927 rtx insn
, cond
, prev
;
2928 regset_head merge_set_head
, tmp_head
, test_live_head
, test_set_head
;
2929 regset merge_set
, tmp
, test_live
, test_set
;
2930 struct propagate_block_info
*pbi
;
2933 /* Check for no calls or trapping operations. */
2934 for (insn
= head
; ; insn
= NEXT_INSN (insn
))
2936 if (GET_CODE (insn
) == CALL_INSN
)
2940 if (may_trap_p (PATTERN (insn
)))
2943 /* ??? Even non-trapping memories such as stack frame
2944 references must be avoided. For stores, we collect
2945 no lifetime info; for reads, we'd have to assert
2946 true_dependence false against every store in the
2948 if (for_each_rtx (&PATTERN (insn
), find_memory
, NULL
))
2955 if (! any_condjump_p (jump
))
2958 /* Find the extent of the conditional. */
2959 cond
= noce_get_condition (jump
, &earliest
);
2964 MERGE_SET = set of registers set in MERGE_BB
2965 TEST_LIVE = set of registers live at EARLIEST
2966 TEST_SET = set of registers set between EARLIEST and the
2967 end of the block. */
2969 tmp
= INITIALIZE_REG_SET (tmp_head
);
2970 merge_set
= INITIALIZE_REG_SET (merge_set_head
);
2971 test_live
= INITIALIZE_REG_SET (test_live_head
);
2972 test_set
= INITIALIZE_REG_SET (test_set_head
);
2974 /* ??? bb->local_set is only valid during calculate_global_regs_live,
2975 so we must recompute usage for MERGE_BB. Not so bad, I suppose,
2976 since we've already asserted that MERGE_BB is small. */
2977 propagate_block (merge_bb
, tmp
, merge_set
, merge_set
, 0);
2979 /* For small register class machines, don't lengthen lifetimes of
2980 hard registers before reload. */
2981 if (SMALL_REGISTER_CLASSES
&& ! reload_completed
)
2983 EXECUTE_IF_SET_IN_BITMAP
2986 if (i
< FIRST_PSEUDO_REGISTER
2988 && ! global_regs
[i
])
2993 /* For TEST, we're interested in a range of insns, not a whole block.
2994 Moreover, we're interested in the insns live from OTHER_BB. */
2996 COPY_REG_SET (test_live
, other_bb
->global_live_at_start
);
2997 pbi
= init_propagate_block_info (test_bb
, test_live
, test_set
, test_set
,
3000 for (insn
= jump
; ; insn
= prev
)
3002 prev
= propagate_one_insn (pbi
, insn
);
3003 if (insn
== earliest
)
3007 free_propagate_block_info (pbi
);
3009 /* We can perform the transformation if
3010 MERGE_SET & (TEST_SET | TEST_LIVE)
3012 TEST_SET & merge_bb->global_live_at_start
3015 bitmap_operation (tmp
, test_set
, test_live
, BITMAP_IOR
);
3016 bitmap_operation (tmp
, tmp
, merge_set
, BITMAP_AND
);
3017 EXECUTE_IF_SET_IN_BITMAP(tmp
, 0, i
, fail
= 1);
3019 bitmap_operation (tmp
, test_set
, merge_bb
->global_live_at_start
,
3021 EXECUTE_IF_SET_IN_BITMAP(tmp
, 0, i
, fail
= 1);
3024 FREE_REG_SET (merge_set
);
3025 FREE_REG_SET (test_live
);
3026 FREE_REG_SET (test_set
);
3033 /* We don't want to use normal invert_jump or redirect_jump because
3034 we don't want to delete_insn called. Also, we want to do our own
3035 change group management. */
3037 old_dest
= JUMP_LABEL (jump
);
3038 if (other_bb
!= new_dest
)
3040 new_label
= block_label (new_dest
);
3042 ? ! invert_jump_1 (jump
, new_label
)
3043 : ! redirect_jump_1 (jump
, new_label
))
3047 if (! apply_change_group ())
3050 if (other_bb
!= new_dest
)
3053 LABEL_NUSES (old_dest
) -= 1;
3055 LABEL_NUSES (new_label
) += 1;
3056 JUMP_LABEL (jump
) = new_label
;
3058 invert_br_probabilities (jump
);
3060 redirect_edge_succ (BRANCH_EDGE (test_bb
), new_dest
);
3063 gcov_type count
, probability
;
3064 count
= BRANCH_EDGE (test_bb
)->count
;
3065 BRANCH_EDGE (test_bb
)->count
= FALLTHRU_EDGE (test_bb
)->count
;
3066 FALLTHRU_EDGE (test_bb
)->count
= count
;
3067 probability
= BRANCH_EDGE (test_bb
)->probability
;
3068 BRANCH_EDGE (test_bb
)->probability
3069 = FALLTHRU_EDGE (test_bb
)->probability
;
3070 FALLTHRU_EDGE (test_bb
)->probability
= probability
;
3071 update_br_prob_note (test_bb
);
3075 /* Move the insns out of MERGE_BB to before the branch. */
3078 if (end
== merge_bb
->end
)
3079 merge_bb
->end
= PREV_INSN (head
);
3081 if (squeeze_notes (&head
, &end
))
3084 reorder_insns (head
, end
, PREV_INSN (earliest
));
3087 /* Remove the jump and edge if we can. */
3088 if (other_bb
== new_dest
)
3091 remove_edge (BRANCH_EDGE (test_bb
));
3092 /* ??? Can't merge blocks here, as then_bb is still in use.
3093 At minimum, the merge will get done just before bb-reorder. */
3103 /* Main entry point for all if-conversion. */
3106 if_convert (int x_life_data_ok
)
3111 num_possible_if_blocks
= 0;
3112 num_updated_if_blocks
= 0;
3113 num_removed_blocks
= 0;
3114 life_data_ok
= (x_life_data_ok
!= 0);
3116 if (! (* targetm
.cannot_modify_jumps_p
) ())
3117 mark_loop_exit_edges ();
3119 /* Free up basic_block_for_insn so that we don't have to keep it
3120 up to date, either here or in merge_blocks. */
3121 free_basic_block_vars (1);
3123 /* Compute postdominators if we think we'll use them. */
3124 post_dominators
= NULL
;
3125 if (HAVE_conditional_execution
|| life_data_ok
)
3127 post_dominators
= calculate_dominance_info (CDI_POST_DOMINATORS
);
3132 /* Go through each of the basic blocks looking for things to convert. If we
3133 have conditional execution, we make multiple passes to allow us to handle
3134 IF-THEN{-ELSE} blocks within other IF-THEN{-ELSE} blocks. */
3138 cond_exec_changed_p
= FALSE
;
3141 #ifdef IFCVT_MULTIPLE_DUMPS
3142 if (rtl_dump_file
&& pass
> 1)
3143 fprintf (rtl_dump_file
, "\n\n========== Pass %d ==========\n", pass
);
3149 while ((new_bb
= find_if_header (bb
, pass
)))
3153 #ifdef IFCVT_MULTIPLE_DUMPS
3154 if (rtl_dump_file
&& cond_exec_changed_p
)
3155 print_rtl_with_bb (rtl_dump_file
, get_insns ());
3158 while (cond_exec_changed_p
);
3160 #ifdef IFCVT_MULTIPLE_DUMPS
3162 fprintf (rtl_dump_file
, "\n\n========== no more changes\n");
3165 if (post_dominators
)
3166 free_dominance_info (post_dominators
);
3169 fflush (rtl_dump_file
);
3171 clear_aux_for_blocks ();
3173 /* Rebuild life info for basic blocks that require it. */
3174 if (num_removed_blocks
&& life_data_ok
)
3176 /* If we allocated new pseudos, we must resize the array for sched1. */
3177 if (max_regno
< max_reg_num ())
3179 max_regno
= max_reg_num ();
3180 allocate_reg_info (max_regno
, FALSE
, FALSE
);
3182 update_life_info_in_dirty_blocks (UPDATE_LIFE_GLOBAL_RM_NOTES
,
3183 PROP_DEATH_NOTES
| PROP_SCAN_DEAD_CODE
3184 | PROP_KILL_DEAD_CODE
);
3187 /* Write the final stats. */
3188 if (rtl_dump_file
&& num_possible_if_blocks
> 0)
3190 fprintf (rtl_dump_file
,
3191 "\n%d possible IF blocks searched.\n",
3192 num_possible_if_blocks
);
3193 fprintf (rtl_dump_file
,
3194 "%d IF blocks converted.\n",
3195 num_updated_if_blocks
);
3196 fprintf (rtl_dump_file
,
3197 "%d basic blocks deleted.\n\n\n",
3198 num_removed_blocks
);
3201 #ifdef ENABLE_CHECKING
3202 verify_flow_info ();