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
)
151 rtx insn
= BB_HEAD (bb
);
155 if (GET_CODE (insn
) == CALL_INSN
|| GET_CODE (insn
) == INSN
)
158 if (insn
== BB_END (bb
))
160 insn
= NEXT_INSN (insn
);
166 /* Return the first non-jump active insn in the basic block. */
169 first_active_insn (basic_block bb
)
171 rtx insn
= BB_HEAD (bb
);
173 if (GET_CODE (insn
) == CODE_LABEL
)
175 if (insn
== BB_END (bb
))
177 insn
= NEXT_INSN (insn
);
180 while (GET_CODE (insn
) == NOTE
)
182 if (insn
== BB_END (bb
))
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
)
198 rtx insn
= BB_END (bb
);
199 rtx head
= BB_HEAD (bb
);
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 (BB_END (test_bb
));
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 (BB_END (test_bb
)))
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
, BB_END (test_bb
));
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 (BB_END (test_bb
), 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 (bb
)))
497 /* Find the conditional jump and isolate the test. */
498 t
= cond_exec_get_condition (BB_END (bb
));
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_move (struct noce_if_info
*);
606 static int noce_try_store_flag (struct noce_if_info
*);
607 static int noce_try_addcc (struct noce_if_info
*);
608 static int noce_try_store_flag_constants (struct noce_if_info
*);
609 static int noce_try_store_flag_mask (struct noce_if_info
*);
610 static rtx
noce_emit_cmove (struct noce_if_info
*, rtx
, enum rtx_code
, rtx
,
612 static int noce_try_cmove (struct noce_if_info
*);
613 static int noce_try_cmove_arith (struct noce_if_info
*);
614 static rtx
noce_get_alt_condition (struct noce_if_info
*, rtx
, rtx
*);
615 static int noce_try_minmax (struct noce_if_info
*);
616 static int noce_try_abs (struct noce_if_info
*);
618 /* Helper function for noce_try_store_flag*. */
621 noce_emit_store_flag (struct noce_if_info
*if_info
, rtx x
, int reversep
,
624 rtx cond
= if_info
->cond
;
628 cond_complex
= (! general_operand (XEXP (cond
, 0), VOIDmode
)
629 || ! general_operand (XEXP (cond
, 1), VOIDmode
));
631 /* If earliest == jump, or when the condition is complex, try to
632 build the store_flag insn directly. */
635 cond
= XEXP (SET_SRC (pc_set (if_info
->jump
)), 0);
638 code
= reversed_comparison_code (cond
, if_info
->jump
);
640 code
= GET_CODE (cond
);
642 if ((if_info
->cond_earliest
== if_info
->jump
|| cond_complex
)
643 && (normalize
== 0 || STORE_FLAG_VALUE
== normalize
))
647 tmp
= gen_rtx_fmt_ee (code
, GET_MODE (x
), XEXP (cond
, 0),
649 tmp
= gen_rtx_SET (VOIDmode
, x
, tmp
);
652 tmp
= emit_insn (tmp
);
654 if (recog_memoized (tmp
) >= 0)
660 if_info
->cond_earliest
= if_info
->jump
;
668 /* Don't even try if the comparison operands or the mode of X are weird. */
669 if (cond_complex
|| !SCALAR_INT_MODE_P (GET_MODE (x
)))
672 return emit_store_flag (x
, code
, XEXP (cond
, 0),
673 XEXP (cond
, 1), VOIDmode
,
674 (code
== LTU
|| code
== LEU
675 || code
== GEU
|| code
== GTU
), normalize
);
678 /* Emit instruction to move an rtx, possibly into STRICT_LOW_PART.
679 X is the destination/target and Y is the value to copy. */
682 noce_emit_move_insn (rtx x
, rtx y
)
684 enum machine_mode outmode
, inmode
;
688 if (GET_CODE (x
) != STRICT_LOW_PART
)
690 emit_move_insn (x
, y
);
695 inner
= XEXP (outer
, 0);
696 outmode
= GET_MODE (outer
);
697 inmode
= GET_MODE (inner
);
698 bitpos
= SUBREG_BYTE (outer
) * BITS_PER_UNIT
;
699 store_bit_field (inner
, GET_MODE_BITSIZE (outmode
), bitpos
, outmode
, y
,
700 GET_MODE_BITSIZE (inmode
));
703 /* Unshare sequence SEQ produced by if conversion. We care to mark
704 all arguments that may be shared with outer instruction stream. */
706 unshare_ifcvt_sequence (struct noce_if_info
*if_info
, rtx seq
)
708 set_used_flags (if_info
->x
);
709 set_used_flags (if_info
->cond
);
710 unshare_all_rtl_in_chain (seq
);
713 /* Convert "if (a != b) x = a; else x = b" into "x = a" and
714 "if (a == b) x = a; else x = b" into "x = b". */
717 noce_try_move (struct noce_if_info
*if_info
)
719 rtx cond
= if_info
->cond
;
720 enum rtx_code code
= GET_CODE (cond
);
723 if (code
!= NE
&& code
!= EQ
)
726 /* This optimization isn't valid if either A or B could be a NaN
728 if (HONOR_NANS (GET_MODE (if_info
->x
))
729 || HONOR_SIGNED_ZEROS (GET_MODE (if_info
->x
)))
732 /* Check whether the operands of the comparison are A and in
734 if ((rtx_equal_p (if_info
->a
, XEXP (cond
, 0))
735 && rtx_equal_p (if_info
->b
, XEXP (cond
, 1)))
736 || (rtx_equal_p (if_info
->a
, XEXP (cond
, 1))
737 && rtx_equal_p (if_info
->b
, XEXP (cond
, 0))))
739 y
= (code
== EQ
) ? if_info
->a
: if_info
->b
;
741 /* Avoid generating the move if the source is the destination. */
742 if (! rtx_equal_p (if_info
->x
, y
))
745 noce_emit_move_insn (if_info
->x
, y
);
747 unshare_ifcvt_sequence (if_info
, seq
);
749 emit_insn_before_setloc (seq
, if_info
->jump
,
750 INSN_LOCATOR (if_info
->insn_a
));
757 /* Convert "if (test) x = 1; else x = 0".
759 Only try 0 and STORE_FLAG_VALUE here. Other combinations will be
760 tried in noce_try_store_flag_constants after noce_try_cmove has had
761 a go at the conversion. */
764 noce_try_store_flag (struct noce_if_info
*if_info
)
769 if (GET_CODE (if_info
->b
) == CONST_INT
770 && INTVAL (if_info
->b
) == STORE_FLAG_VALUE
771 && if_info
->a
== const0_rtx
)
773 else if (if_info
->b
== const0_rtx
774 && GET_CODE (if_info
->a
) == CONST_INT
775 && INTVAL (if_info
->a
) == STORE_FLAG_VALUE
776 && (reversed_comparison_code (if_info
->cond
, if_info
->jump
)
784 target
= noce_emit_store_flag (if_info
, if_info
->x
, reversep
, 0);
787 if (target
!= if_info
->x
)
788 noce_emit_move_insn (if_info
->x
, target
);
791 unshare_ifcvt_sequence (if_info
, seq
);
793 emit_insn_before_setloc (seq
, if_info
->jump
, INSN_LOCATOR (if_info
->insn_a
));
804 /* Convert "if (test) x = a; else x = b", for A and B constant. */
807 noce_try_store_flag_constants (struct noce_if_info
*if_info
)
811 HOST_WIDE_INT itrue
, ifalse
, diff
, tmp
;
812 int normalize
, can_reverse
;
813 enum machine_mode mode
;
816 && GET_CODE (if_info
->a
) == CONST_INT
817 && GET_CODE (if_info
->b
) == CONST_INT
)
819 mode
= GET_MODE (if_info
->x
);
820 ifalse
= INTVAL (if_info
->a
);
821 itrue
= INTVAL (if_info
->b
);
823 /* Make sure we can represent the difference between the two values. */
824 if ((itrue
- ifalse
> 0)
825 != ((ifalse
< 0) != (itrue
< 0) ? ifalse
< 0 : ifalse
< itrue
))
828 diff
= trunc_int_for_mode (itrue
- ifalse
, mode
);
830 can_reverse
= (reversed_comparison_code (if_info
->cond
, if_info
->jump
)
834 if (diff
== STORE_FLAG_VALUE
|| diff
== -STORE_FLAG_VALUE
)
836 else if (ifalse
== 0 && exact_log2 (itrue
) >= 0
837 && (STORE_FLAG_VALUE
== 1
838 || BRANCH_COST
>= 2))
840 else if (itrue
== 0 && exact_log2 (ifalse
) >= 0 && can_reverse
841 && (STORE_FLAG_VALUE
== 1 || BRANCH_COST
>= 2))
842 normalize
= 1, reversep
= 1;
844 && (STORE_FLAG_VALUE
== -1
845 || BRANCH_COST
>= 2))
847 else if (ifalse
== -1 && can_reverse
848 && (STORE_FLAG_VALUE
== -1 || BRANCH_COST
>= 2))
849 normalize
= -1, reversep
= 1;
850 else if ((BRANCH_COST
>= 2 && STORE_FLAG_VALUE
== -1)
858 tmp
= itrue
; itrue
= ifalse
; ifalse
= tmp
;
859 diff
= trunc_int_for_mode (-diff
, mode
);
863 target
= noce_emit_store_flag (if_info
, if_info
->x
, reversep
, normalize
);
870 /* if (test) x = 3; else x = 4;
871 => x = 3 + (test == 0); */
872 if (diff
== STORE_FLAG_VALUE
|| diff
== -STORE_FLAG_VALUE
)
874 target
= expand_simple_binop (mode
,
875 (diff
== STORE_FLAG_VALUE
877 GEN_INT (ifalse
), target
, if_info
->x
, 0,
881 /* if (test) x = 8; else x = 0;
882 => x = (test != 0) << 3; */
883 else if (ifalse
== 0 && (tmp
= exact_log2 (itrue
)) >= 0)
885 target
= expand_simple_binop (mode
, ASHIFT
,
886 target
, GEN_INT (tmp
), if_info
->x
, 0,
890 /* if (test) x = -1; else x = b;
891 => x = -(test != 0) | b; */
892 else if (itrue
== -1)
894 target
= expand_simple_binop (mode
, IOR
,
895 target
, GEN_INT (ifalse
), if_info
->x
, 0,
899 /* if (test) x = a; else x = b;
900 => x = (-(test != 0) & (b - a)) + a; */
903 target
= expand_simple_binop (mode
, AND
,
904 target
, GEN_INT (diff
), if_info
->x
, 0,
907 target
= expand_simple_binop (mode
, PLUS
,
908 target
, GEN_INT (ifalse
),
909 if_info
->x
, 0, OPTAB_WIDEN
);
918 if (target
!= if_info
->x
)
919 noce_emit_move_insn (if_info
->x
, target
);
922 unshare_ifcvt_sequence (if_info
, seq
);
925 if (seq_contains_jump (seq
))
928 emit_insn_before_setloc (seq
, if_info
->jump
, INSN_LOCATOR (if_info
->insn_a
));
936 /* Convert "if (test) foo++" into "foo += (test != 0)", and
937 similarly for "foo--". */
940 noce_try_addcc (struct noce_if_info
*if_info
)
943 int subtract
, normalize
;
946 && GET_CODE (if_info
->a
) == PLUS
947 && rtx_equal_p (XEXP (if_info
->a
, 0), if_info
->b
)
948 && (reversed_comparison_code (if_info
->cond
, if_info
->jump
)
951 rtx cond
= if_info
->cond
;
952 enum rtx_code code
= reversed_comparison_code (cond
, if_info
->jump
);
954 /* First try to use addcc pattern. */
955 if (general_operand (XEXP (cond
, 0), VOIDmode
)
956 && general_operand (XEXP (cond
, 1), VOIDmode
))
959 target
= emit_conditional_add (if_info
->x
, code
,
964 XEXP (if_info
->a
, 1),
965 GET_MODE (if_info
->x
),
966 (code
== LTU
|| code
== GEU
967 || code
== LEU
|| code
== GTU
));
970 if (target
!= if_info
->x
)
971 noce_emit_move_insn (if_info
->x
, target
);
974 unshare_ifcvt_sequence (if_info
, seq
);
976 emit_insn_before_setloc (seq
, if_info
->jump
,
977 INSN_LOCATOR (if_info
->insn_a
));
983 /* If that fails, construct conditional increment or decrement using
986 && (XEXP (if_info
->a
, 1) == const1_rtx
987 || XEXP (if_info
->a
, 1) == constm1_rtx
))
990 if (STORE_FLAG_VALUE
== INTVAL (XEXP (if_info
->a
, 1)))
991 subtract
= 0, normalize
= 0;
992 else if (-STORE_FLAG_VALUE
== INTVAL (XEXP (if_info
->a
, 1)))
993 subtract
= 1, normalize
= 0;
995 subtract
= 0, normalize
= INTVAL (XEXP (if_info
->a
, 1));
998 target
= noce_emit_store_flag (if_info
,
999 gen_reg_rtx (GET_MODE (if_info
->x
)),
1003 target
= expand_simple_binop (GET_MODE (if_info
->x
),
1004 subtract
? MINUS
: PLUS
,
1005 if_info
->b
, target
, if_info
->x
,
1009 if (target
!= if_info
->x
)
1010 noce_emit_move_insn (if_info
->x
, target
);
1013 unshare_ifcvt_sequence (if_info
, seq
);
1016 if (seq_contains_jump (seq
))
1019 emit_insn_before_setloc (seq
, if_info
->jump
,
1020 INSN_LOCATOR (if_info
->insn_a
));
1031 /* Convert "if (test) x = 0;" to "x &= -(test == 0);" */
1034 noce_try_store_flag_mask (struct noce_if_info
*if_info
)
1040 if (! no_new_pseudos
1041 && (BRANCH_COST
>= 2
1042 || STORE_FLAG_VALUE
== -1)
1043 && ((if_info
->a
== const0_rtx
1044 && rtx_equal_p (if_info
->b
, if_info
->x
))
1045 || ((reversep
= (reversed_comparison_code (if_info
->cond
,
1048 && if_info
->b
== const0_rtx
1049 && rtx_equal_p (if_info
->a
, if_info
->x
))))
1052 target
= noce_emit_store_flag (if_info
,
1053 gen_reg_rtx (GET_MODE (if_info
->x
)),
1056 target
= expand_simple_binop (GET_MODE (if_info
->x
), AND
,
1058 target
, if_info
->x
, 0,
1063 if (target
!= if_info
->x
)
1064 noce_emit_move_insn (if_info
->x
, target
);
1067 unshare_ifcvt_sequence (if_info
, seq
);
1070 if (seq_contains_jump (seq
))
1073 emit_insn_before_setloc (seq
, if_info
->jump
,
1074 INSN_LOCATOR (if_info
->insn_a
));
1085 /* Helper function for noce_try_cmove and noce_try_cmove_arith. */
1088 noce_emit_cmove (struct noce_if_info
*if_info
, rtx x
, enum rtx_code code
,
1089 rtx cmp_a
, rtx cmp_b
, rtx vfalse
, rtx vtrue
)
1091 /* If earliest == jump, try to build the cmove insn directly.
1092 This is helpful when combine has created some complex condition
1093 (like for alpha's cmovlbs) that we can't hope to regenerate
1094 through the normal interface. */
1096 if (if_info
->cond_earliest
== if_info
->jump
)
1100 tmp
= gen_rtx_fmt_ee (code
, GET_MODE (if_info
->cond
), cmp_a
, cmp_b
);
1101 tmp
= gen_rtx_IF_THEN_ELSE (GET_MODE (x
), tmp
, vtrue
, vfalse
);
1102 tmp
= gen_rtx_SET (VOIDmode
, x
, tmp
);
1105 tmp
= emit_insn (tmp
);
1107 if (recog_memoized (tmp
) >= 0)
1119 /* Don't even try if the comparison operands are weird. */
1120 if (! general_operand (cmp_a
, GET_MODE (cmp_a
))
1121 || ! general_operand (cmp_b
, GET_MODE (cmp_b
)))
1124 #if HAVE_conditional_move
1125 return emit_conditional_move (x
, code
, cmp_a
, cmp_b
, VOIDmode
,
1126 vtrue
, vfalse
, GET_MODE (x
),
1127 (code
== LTU
|| code
== GEU
1128 || code
== LEU
|| code
== GTU
));
1130 /* We'll never get here, as noce_process_if_block doesn't call the
1131 functions involved. Ifdef code, however, should be discouraged
1132 because it leads to typos in the code not selected. However,
1133 emit_conditional_move won't exist either. */
1138 /* Try only simple constants and registers here. More complex cases
1139 are handled in noce_try_cmove_arith after noce_try_store_flag_arith
1140 has had a go at it. */
1143 noce_try_cmove (struct noce_if_info
*if_info
)
1148 if ((CONSTANT_P (if_info
->a
) || register_operand (if_info
->a
, VOIDmode
))
1149 && (CONSTANT_P (if_info
->b
) || register_operand (if_info
->b
, VOIDmode
)))
1153 code
= GET_CODE (if_info
->cond
);
1154 target
= noce_emit_cmove (if_info
, if_info
->x
, code
,
1155 XEXP (if_info
->cond
, 0),
1156 XEXP (if_info
->cond
, 1),
1157 if_info
->a
, if_info
->b
);
1161 if (target
!= if_info
->x
)
1162 noce_emit_move_insn (if_info
->x
, target
);
1165 unshare_ifcvt_sequence (if_info
, seq
);
1167 emit_insn_before_setloc (seq
, if_info
->jump
,
1168 INSN_LOCATOR (if_info
->insn_a
));
1181 /* Try more complex cases involving conditional_move. */
1184 noce_try_cmove_arith (struct noce_if_info
*if_info
)
1194 /* A conditional move from two memory sources is equivalent to a
1195 conditional on their addresses followed by a load. Don't do this
1196 early because it'll screw alias analysis. Note that we've
1197 already checked for no side effects. */
1198 if (! no_new_pseudos
&& cse_not_expected
1199 && GET_CODE (a
) == MEM
&& GET_CODE (b
) == MEM
1200 && BRANCH_COST
>= 5)
1204 x
= gen_reg_rtx (Pmode
);
1208 /* ??? We could handle this if we knew that a load from A or B could
1209 not fault. This is also true if we've already loaded
1210 from the address along the path from ENTRY. */
1211 else if (may_trap_p (a
) || may_trap_p (b
))
1214 /* if (test) x = a + b; else x = c - d;
1221 code
= GET_CODE (if_info
->cond
);
1222 insn_a
= if_info
->insn_a
;
1223 insn_b
= if_info
->insn_b
;
1225 /* Possibly rearrange operands to make things come out more natural. */
1226 if (reversed_comparison_code (if_info
->cond
, if_info
->jump
) != UNKNOWN
)
1229 if (rtx_equal_p (b
, x
))
1231 else if (general_operand (b
, GET_MODE (b
)))
1236 code
= reversed_comparison_code (if_info
->cond
, if_info
->jump
);
1237 tmp
= a
, a
= b
, b
= tmp
;
1238 tmp
= insn_a
, insn_a
= insn_b
, insn_b
= tmp
;
1244 /* If either operand is complex, load it into a register first.
1245 The best way to do this is to copy the original insn. In this
1246 way we preserve any clobbers etc that the insn may have had.
1247 This is of course not possible in the IS_MEM case. */
1248 if (! general_operand (a
, GET_MODE (a
)))
1253 goto end_seq_and_fail
;
1257 tmp
= gen_reg_rtx (GET_MODE (a
));
1258 tmp
= emit_insn (gen_rtx_SET (VOIDmode
, tmp
, a
));
1261 goto end_seq_and_fail
;
1264 a
= gen_reg_rtx (GET_MODE (a
));
1265 tmp
= copy_rtx (insn_a
);
1266 set
= single_set (tmp
);
1268 tmp
= emit_insn (PATTERN (tmp
));
1270 if (recog_memoized (tmp
) < 0)
1271 goto end_seq_and_fail
;
1273 if (! general_operand (b
, GET_MODE (b
)))
1278 goto end_seq_and_fail
;
1282 tmp
= gen_reg_rtx (GET_MODE (b
));
1283 tmp
= emit_insn (gen_rtx_SET (VOIDmode
,
1288 goto end_seq_and_fail
;
1291 b
= gen_reg_rtx (GET_MODE (b
));
1292 tmp
= copy_rtx (insn_b
);
1293 set
= single_set (tmp
);
1295 tmp
= emit_insn (PATTERN (tmp
));
1297 if (recog_memoized (tmp
) < 0)
1298 goto end_seq_and_fail
;
1301 target
= noce_emit_cmove (if_info
, x
, code
, XEXP (if_info
->cond
, 0),
1302 XEXP (if_info
->cond
, 1), a
, b
);
1305 goto end_seq_and_fail
;
1307 /* If we're handling a memory for above, emit the load now. */
1310 tmp
= gen_rtx_MEM (GET_MODE (if_info
->x
), target
);
1312 /* Copy over flags as appropriate. */
1313 if (MEM_VOLATILE_P (if_info
->a
) || MEM_VOLATILE_P (if_info
->b
))
1314 MEM_VOLATILE_P (tmp
) = 1;
1315 if (MEM_IN_STRUCT_P (if_info
->a
) && MEM_IN_STRUCT_P (if_info
->b
))
1316 MEM_IN_STRUCT_P (tmp
) = 1;
1317 if (MEM_SCALAR_P (if_info
->a
) && MEM_SCALAR_P (if_info
->b
))
1318 MEM_SCALAR_P (tmp
) = 1;
1319 if (MEM_ALIAS_SET (if_info
->a
) == MEM_ALIAS_SET (if_info
->b
))
1320 set_mem_alias_set (tmp
, MEM_ALIAS_SET (if_info
->a
));
1322 MIN (MEM_ALIGN (if_info
->a
), MEM_ALIGN (if_info
->b
)));
1324 noce_emit_move_insn (if_info
->x
, tmp
);
1326 else if (target
!= x
)
1327 noce_emit_move_insn (x
, target
);
1330 unshare_ifcvt_sequence (if_info
, tmp
);
1332 emit_insn_before_setloc (tmp
, if_info
->jump
, INSN_LOCATOR (if_info
->insn_a
));
1340 /* For most cases, the simplified condition we found is the best
1341 choice, but this is not the case for the min/max/abs transforms.
1342 For these we wish to know that it is A or B in the condition. */
1345 noce_get_alt_condition (struct noce_if_info
*if_info
, rtx target
,
1348 rtx cond
, set
, insn
;
1351 /* If target is already mentioned in the known condition, return it. */
1352 if (reg_mentioned_p (target
, if_info
->cond
))
1354 *earliest
= if_info
->cond_earliest
;
1355 return if_info
->cond
;
1358 set
= pc_set (if_info
->jump
);
1359 cond
= XEXP (SET_SRC (set
), 0);
1361 = GET_CODE (XEXP (SET_SRC (set
), 2)) == LABEL_REF
1362 && XEXP (XEXP (SET_SRC (set
), 2), 0) == JUMP_LABEL (if_info
->jump
);
1364 /* If we're looking for a constant, try to make the conditional
1365 have that constant in it. There are two reasons why it may
1366 not have the constant we want:
1368 1. GCC may have needed to put the constant in a register, because
1369 the target can't compare directly against that constant. For
1370 this case, we look for a SET immediately before the comparison
1371 that puts a constant in that register.
1373 2. GCC may have canonicalized the conditional, for example
1374 replacing "if x < 4" with "if x <= 3". We can undo that (or
1375 make equivalent types of changes) to get the constants we need
1376 if they're off by one in the right direction. */
1378 if (GET_CODE (target
) == CONST_INT
)
1380 enum rtx_code code
= GET_CODE (if_info
->cond
);
1381 rtx op_a
= XEXP (if_info
->cond
, 0);
1382 rtx op_b
= XEXP (if_info
->cond
, 1);
1385 /* First, look to see if we put a constant in a register. */
1386 prev_insn
= PREV_INSN (if_info
->cond_earliest
);
1388 && INSN_P (prev_insn
)
1389 && GET_CODE (PATTERN (prev_insn
)) == SET
)
1391 rtx src
= find_reg_equal_equiv_note (prev_insn
);
1393 src
= SET_SRC (PATTERN (prev_insn
));
1394 if (GET_CODE (src
) == CONST_INT
)
1396 if (rtx_equal_p (op_a
, SET_DEST (PATTERN (prev_insn
))))
1398 else if (rtx_equal_p (op_b
, SET_DEST (PATTERN (prev_insn
))))
1401 if (GET_CODE (op_a
) == CONST_INT
)
1406 code
= swap_condition (code
);
1411 /* Now, look to see if we can get the right constant by
1412 adjusting the conditional. */
1413 if (GET_CODE (op_b
) == CONST_INT
)
1415 HOST_WIDE_INT desired_val
= INTVAL (target
);
1416 HOST_WIDE_INT actual_val
= INTVAL (op_b
);
1421 if (actual_val
== desired_val
+ 1)
1424 op_b
= GEN_INT (desired_val
);
1428 if (actual_val
== desired_val
- 1)
1431 op_b
= GEN_INT (desired_val
);
1435 if (actual_val
== desired_val
- 1)
1438 op_b
= GEN_INT (desired_val
);
1442 if (actual_val
== desired_val
+ 1)
1445 op_b
= GEN_INT (desired_val
);
1453 /* If we made any changes, generate a new conditional that is
1454 equivalent to what we started with, but has the right
1456 if (code
!= GET_CODE (if_info
->cond
)
1457 || op_a
!= XEXP (if_info
->cond
, 0)
1458 || op_b
!= XEXP (if_info
->cond
, 1))
1460 cond
= gen_rtx_fmt_ee (code
, GET_MODE (cond
), op_a
, op_b
);
1461 *earliest
= if_info
->cond_earliest
;
1466 cond
= canonicalize_condition (if_info
->jump
, cond
, reverse
,
1467 earliest
, target
, false);
1468 if (! cond
|| ! reg_mentioned_p (target
, cond
))
1471 /* We almost certainly searched back to a different place.
1472 Need to re-verify correct lifetimes. */
1474 /* X may not be mentioned in the range (cond_earliest, jump]. */
1475 for (insn
= if_info
->jump
; insn
!= *earliest
; insn
= PREV_INSN (insn
))
1476 if (INSN_P (insn
) && reg_overlap_mentioned_p (if_info
->x
, PATTERN (insn
)))
1479 /* A and B may not be modified in the range [cond_earliest, jump). */
1480 for (insn
= *earliest
; insn
!= if_info
->jump
; insn
= NEXT_INSN (insn
))
1482 && (modified_in_p (if_info
->a
, insn
)
1483 || modified_in_p (if_info
->b
, insn
)))
1489 /* Convert "if (a < b) x = a; else x = b;" to "x = min(a, b);", etc. */
1492 noce_try_minmax (struct noce_if_info
*if_info
)
1494 rtx cond
, earliest
, target
, seq
;
1495 enum rtx_code code
, op
;
1498 /* ??? Can't guarantee that expand_binop won't create pseudos. */
1502 /* ??? Reject modes with NaNs or signed zeros since we don't know how
1503 they will be resolved with an SMIN/SMAX. It wouldn't be too hard
1504 to get the target to tell us... */
1505 if (HONOR_SIGNED_ZEROS (GET_MODE (if_info
->x
))
1506 || HONOR_NANS (GET_MODE (if_info
->x
)))
1509 cond
= noce_get_alt_condition (if_info
, if_info
->a
, &earliest
);
1513 /* Verify the condition is of the form we expect, and canonicalize
1514 the comparison code. */
1515 code
= GET_CODE (cond
);
1516 if (rtx_equal_p (XEXP (cond
, 0), if_info
->a
))
1518 if (! rtx_equal_p (XEXP (cond
, 1), if_info
->b
))
1521 else if (rtx_equal_p (XEXP (cond
, 1), if_info
->a
))
1523 if (! rtx_equal_p (XEXP (cond
, 0), if_info
->b
))
1525 code
= swap_condition (code
);
1530 /* Determine what sort of operation this is. Note that the code is for
1531 a taken branch, so the code->operation mapping appears backwards. */
1564 target
= expand_simple_binop (GET_MODE (if_info
->x
), op
,
1565 if_info
->a
, if_info
->b
,
1566 if_info
->x
, unsignedp
, OPTAB_WIDEN
);
1572 if (target
!= if_info
->x
)
1573 noce_emit_move_insn (if_info
->x
, target
);
1576 unshare_ifcvt_sequence (if_info
, seq
);
1579 if (seq_contains_jump (seq
))
1582 emit_insn_before_setloc (seq
, if_info
->jump
, INSN_LOCATOR (if_info
->insn_a
));
1583 if_info
->cond
= cond
;
1584 if_info
->cond_earliest
= earliest
;
1589 /* Convert "if (a < 0) x = -a; else x = a;" to "x = abs(a);", etc. */
1592 noce_try_abs (struct noce_if_info
*if_info
)
1594 rtx cond
, earliest
, target
, seq
, a
, b
, c
;
1597 /* ??? Can't guarantee that expand_binop won't create pseudos. */
1601 /* Recognize A and B as constituting an ABS or NABS. */
1604 if (GET_CODE (a
) == NEG
&& rtx_equal_p (XEXP (a
, 0), b
))
1606 else if (GET_CODE (b
) == NEG
&& rtx_equal_p (XEXP (b
, 0), a
))
1608 c
= a
; a
= b
; b
= c
;
1614 cond
= noce_get_alt_condition (if_info
, b
, &earliest
);
1618 /* Verify the condition is of the form we expect. */
1619 if (rtx_equal_p (XEXP (cond
, 0), b
))
1621 else if (rtx_equal_p (XEXP (cond
, 1), b
))
1626 /* Verify that C is zero. Search backward through the block for
1627 a REG_EQUAL note if necessary. */
1630 rtx insn
, note
= NULL
;
1631 for (insn
= earliest
;
1632 insn
!= BB_HEAD (if_info
->test_bb
);
1633 insn
= PREV_INSN (insn
))
1635 && ((note
= find_reg_note (insn
, REG_EQUAL
, c
))
1636 || (note
= find_reg_note (insn
, REG_EQUIV
, c
))))
1642 if (GET_CODE (c
) == MEM
1643 && GET_CODE (XEXP (c
, 0)) == SYMBOL_REF
1644 && CONSTANT_POOL_ADDRESS_P (XEXP (c
, 0)))
1645 c
= get_pool_constant (XEXP (c
, 0));
1647 /* Work around funny ideas get_condition has wrt canonicalization.
1648 Note that these rtx constants are known to be CONST_INT, and
1649 therefore imply integer comparisons. */
1650 if (c
== constm1_rtx
&& GET_CODE (cond
) == GT
)
1652 else if (c
== const1_rtx
&& GET_CODE (cond
) == LT
)
1654 else if (c
!= CONST0_RTX (GET_MODE (b
)))
1657 /* Determine what sort of operation this is. */
1658 switch (GET_CODE (cond
))
1677 target
= expand_abs_nojump (GET_MODE (if_info
->x
), b
, if_info
->x
, 1);
1679 /* ??? It's a quandary whether cmove would be better here, especially
1680 for integers. Perhaps combine will clean things up. */
1681 if (target
&& negate
)
1682 target
= expand_simple_unop (GET_MODE (target
), NEG
, target
, if_info
->x
, 0);
1690 if (target
!= if_info
->x
)
1691 noce_emit_move_insn (if_info
->x
, target
);
1694 unshare_ifcvt_sequence (if_info
, seq
);
1697 if (seq_contains_jump (seq
))
1700 emit_insn_before_setloc (seq
, if_info
->jump
, INSN_LOCATOR (if_info
->insn_a
));
1701 if_info
->cond
= cond
;
1702 if_info
->cond_earliest
= earliest
;
1707 /* Similar to get_condition, only the resulting condition must be
1708 valid at JUMP, instead of at EARLIEST. */
1711 noce_get_condition (rtx jump
, rtx
*earliest
)
1713 rtx cond
, set
, tmp
, insn
;
1716 if (! any_condjump_p (jump
))
1719 set
= pc_set (jump
);
1721 /* If this branches to JUMP_LABEL when the condition is false,
1722 reverse the condition. */
1723 reverse
= (GET_CODE (XEXP (SET_SRC (set
), 2)) == LABEL_REF
1724 && XEXP (XEXP (SET_SRC (set
), 2), 0) == JUMP_LABEL (jump
));
1726 /* If the condition variable is a register and is MODE_INT, accept it. */
1728 cond
= XEXP (SET_SRC (set
), 0);
1729 tmp
= XEXP (cond
, 0);
1730 if (REG_P (tmp
) && GET_MODE_CLASS (GET_MODE (tmp
)) == MODE_INT
)
1735 cond
= gen_rtx_fmt_ee (reverse_condition (GET_CODE (cond
)),
1736 GET_MODE (cond
), tmp
, XEXP (cond
, 1));
1740 /* Otherwise, fall back on canonicalize_condition to do the dirty
1741 work of manipulating MODE_CC values and COMPARE rtx codes. */
1743 tmp
= canonicalize_condition (jump
, cond
, reverse
, earliest
, NULL_RTX
,
1748 /* We are going to insert code before JUMP, not before EARLIEST.
1749 We must therefore be certain that the given condition is valid
1750 at JUMP by virtue of not having been modified since. */
1751 for (insn
= *earliest
; insn
!= jump
; insn
= NEXT_INSN (insn
))
1752 if (INSN_P (insn
) && modified_in_p (tmp
, insn
))
1757 /* The condition was modified. See if we can get a partial result
1758 that doesn't follow all the reversals. Perhaps combine can fold
1759 them together later. */
1760 tmp
= XEXP (tmp
, 0);
1761 if (!REG_P (tmp
) || GET_MODE_CLASS (GET_MODE (tmp
)) != MODE_INT
)
1763 tmp
= canonicalize_condition (jump
, cond
, reverse
, earliest
, tmp
,
1768 /* For sanity's sake, re-validate the new result. */
1769 for (insn
= *earliest
; insn
!= jump
; insn
= NEXT_INSN (insn
))
1770 if (INSN_P (insn
) && modified_in_p (tmp
, insn
))
1776 /* Return true if OP is ok for if-then-else processing. */
1779 noce_operand_ok (rtx op
)
1781 /* We special-case memories, so handle any of them with
1782 no address side effects. */
1783 if (GET_CODE (op
) == MEM
)
1784 return ! side_effects_p (XEXP (op
, 0));
1786 if (side_effects_p (op
))
1789 return ! may_trap_p (op
);
1792 /* Given a simple IF-THEN or IF-THEN-ELSE block, attempt to convert it
1793 without using conditional execution. Return TRUE if we were
1794 successful at converting the block. */
1797 noce_process_if_block (struct ce_if_block
* ce_info
)
1799 basic_block test_bb
= ce_info
->test_bb
; /* test block */
1800 basic_block then_bb
= ce_info
->then_bb
; /* THEN */
1801 basic_block else_bb
= ce_info
->else_bb
; /* ELSE or NULL */
1802 struct noce_if_info if_info
;
1805 rtx orig_x
, x
, a
, b
;
1808 /* We're looking for patterns of the form
1810 (1) if (...) x = a; else x = b;
1811 (2) x = b; if (...) x = a;
1812 (3) if (...) x = a; // as if with an initial x = x.
1814 The later patterns require jumps to be more expensive.
1816 ??? For future expansion, look for multiple X in such patterns. */
1818 /* If test is comprised of && or || elements, don't handle it unless it is
1819 the special case of && elements without an ELSE block. */
1820 if (ce_info
->num_multiple_test_blocks
)
1822 if (else_bb
|| ! ce_info
->and_and_p
)
1825 ce_info
->test_bb
= test_bb
= ce_info
->last_test_bb
;
1826 ce_info
->num_multiple_test_blocks
= 0;
1827 ce_info
->num_and_and_blocks
= 0;
1828 ce_info
->num_or_or_blocks
= 0;
1831 /* If this is not a standard conditional jump, we can't parse it. */
1832 jump
= BB_END (test_bb
);
1833 cond
= noce_get_condition (jump
, &if_info
.cond_earliest
);
1837 /* If the conditional jump is more than just a conditional
1838 jump, then we can not do if-conversion on this block. */
1839 if (! onlyjump_p (jump
))
1842 /* We must be comparing objects whose modes imply the size. */
1843 if (GET_MODE (XEXP (cond
, 0)) == BLKmode
)
1846 /* Look for one of the potential sets. */
1847 insn_a
= first_active_insn (then_bb
);
1849 || insn_a
!= last_active_insn (then_bb
, FALSE
)
1850 || (set_a
= single_set (insn_a
)) == NULL_RTX
)
1853 x
= SET_DEST (set_a
);
1854 a
= SET_SRC (set_a
);
1856 /* Look for the other potential set. Make sure we've got equivalent
1858 /* ??? This is overconservative. Storing to two different mems is
1859 as easy as conditionally computing the address. Storing to a
1860 single mem merely requires a scratch memory to use as one of the
1861 destination addresses; often the memory immediately below the
1862 stack pointer is available for this. */
1866 insn_b
= first_active_insn (else_bb
);
1868 || insn_b
!= last_active_insn (else_bb
, FALSE
)
1869 || (set_b
= single_set (insn_b
)) == NULL_RTX
1870 || ! rtx_equal_p (x
, SET_DEST (set_b
)))
1875 insn_b
= prev_nonnote_insn (if_info
.cond_earliest
);
1876 /* We're going to be moving the evaluation of B down from above
1877 COND_EARLIEST to JUMP. Make sure the relevant data is still
1880 || GET_CODE (insn_b
) != INSN
1881 || (set_b
= single_set (insn_b
)) == NULL_RTX
1882 || ! rtx_equal_p (x
, SET_DEST (set_b
))
1883 || reg_overlap_mentioned_p (x
, SET_SRC (set_b
))
1884 || modified_between_p (SET_SRC (set_b
),
1885 PREV_INSN (if_info
.cond_earliest
), jump
)
1886 /* Likewise with X. In particular this can happen when
1887 noce_get_condition looks farther back in the instruction
1888 stream than one might expect. */
1889 || reg_overlap_mentioned_p (x
, cond
)
1890 || reg_overlap_mentioned_p (x
, a
)
1891 || modified_between_p (x
, PREV_INSN (if_info
.cond_earliest
), jump
))
1892 insn_b
= set_b
= NULL_RTX
;
1895 /* If x has side effects then only the if-then-else form is safe to
1896 convert. But even in that case we would need to restore any notes
1897 (such as REG_INC) at then end. That can be tricky if
1898 noce_emit_move_insn expands to more than one insn, so disable the
1899 optimization entirely for now if there are side effects. */
1900 if (side_effects_p (x
))
1903 b
= (set_b
? SET_SRC (set_b
) : x
);
1905 /* Only operate on register destinations, and even then avoid extending
1906 the lifetime of hard registers on small register class machines. */
1908 if (GET_CODE (x
) != REG
1909 || (SMALL_REGISTER_CLASSES
1910 && REGNO (x
) < FIRST_PSEUDO_REGISTER
))
1912 if (no_new_pseudos
|| GET_MODE (x
) == BLKmode
)
1914 x
= gen_reg_rtx (GET_MODE (GET_CODE (x
) == STRICT_LOW_PART
1915 ? XEXP (x
, 0) : x
));
1918 /* Don't operate on sources that may trap or are volatile. */
1919 if (! noce_operand_ok (a
) || ! noce_operand_ok (b
))
1922 /* Set up the info block for our subroutines. */
1923 if_info
.test_bb
= test_bb
;
1924 if_info
.cond
= cond
;
1925 if_info
.jump
= jump
;
1926 if_info
.insn_a
= insn_a
;
1927 if_info
.insn_b
= insn_b
;
1932 /* Try optimizations in some approximation of a useful order. */
1933 /* ??? Should first look to see if X is live incoming at all. If it
1934 isn't, we don't need anything but an unconditional set. */
1936 /* Look and see if A and B are really the same. Avoid creating silly
1937 cmove constructs that no one will fix up later. */
1938 if (rtx_equal_p (a
, b
))
1940 /* If we have an INSN_B, we don't have to create any new rtl. Just
1941 move the instruction that we already have. If we don't have an
1942 INSN_B, that means that A == X, and we've got a noop move. In
1943 that case don't do anything and let the code below delete INSN_A. */
1944 if (insn_b
&& else_bb
)
1948 if (else_bb
&& insn_b
== BB_END (else_bb
))
1949 BB_END (else_bb
) = PREV_INSN (insn_b
);
1950 reorder_insns (insn_b
, insn_b
, PREV_INSN (jump
));
1952 /* If there was a REG_EQUAL note, delete it since it may have been
1953 true due to this insn being after a jump. */
1954 if ((note
= find_reg_note (insn_b
, REG_EQUAL
, NULL_RTX
)) != 0)
1955 remove_note (insn_b
, note
);
1959 /* If we have "x = b; if (...) x = a;", and x has side-effects, then
1960 x must be executed twice. */
1961 else if (insn_b
&& side_effects_p (orig_x
))
1968 if (noce_try_move (&if_info
))
1970 if (noce_try_store_flag (&if_info
))
1972 if (noce_try_minmax (&if_info
))
1974 if (noce_try_abs (&if_info
))
1976 if (HAVE_conditional_move
1977 && noce_try_cmove (&if_info
))
1979 if (! HAVE_conditional_execution
)
1981 if (noce_try_store_flag_constants (&if_info
))
1983 if (noce_try_addcc (&if_info
))
1985 if (noce_try_store_flag_mask (&if_info
))
1987 if (HAVE_conditional_move
1988 && noce_try_cmove_arith (&if_info
))
1995 /* The original sets may now be killed. */
1996 delete_insn (insn_a
);
1998 /* Several special cases here: First, we may have reused insn_b above,
1999 in which case insn_b is now NULL. Second, we want to delete insn_b
2000 if it came from the ELSE block, because follows the now correct
2001 write that appears in the TEST block. However, if we got insn_b from
2002 the TEST block, it may in fact be loading data needed for the comparison.
2003 We'll let life_analysis remove the insn if it's really dead. */
2004 if (insn_b
&& else_bb
)
2005 delete_insn (insn_b
);
2007 /* The new insns will have been inserted immediately before the jump. We
2008 should be able to remove the jump with impunity, but the condition itself
2009 may have been modified by gcse to be shared across basic blocks. */
2012 /* If we used a temporary, fix it up now. */
2016 noce_emit_move_insn (orig_x
, x
);
2017 insn_b
= get_insns ();
2018 set_used_flags (orig_x
);
2019 unshare_all_rtl_in_chain (insn_b
);
2022 emit_insn_after_setloc (insn_b
, BB_END (test_bb
), INSN_LOCATOR (insn_a
));
2025 /* Merge the blocks! */
2026 merge_if_block (ce_info
);
2031 /* Attempt to convert an IF-THEN or IF-THEN-ELSE block into
2032 straight line code. Return true if successful. */
2035 process_if_block (struct ce_if_block
* ce_info
)
2037 if (! reload_completed
2038 && noce_process_if_block (ce_info
))
2041 if (HAVE_conditional_execution
&& reload_completed
)
2043 /* If we have && and || tests, try to first handle combining the && and
2044 || tests into the conditional code, and if that fails, go back and
2045 handle it without the && and ||, which at present handles the && case
2046 if there was no ELSE block. */
2047 if (cond_exec_process_if_block (ce_info
, TRUE
))
2050 if (ce_info
->num_multiple_test_blocks
)
2054 if (cond_exec_process_if_block (ce_info
, FALSE
))
2062 /* Merge the blocks and mark for local life update. */
2065 merge_if_block (struct ce_if_block
* ce_info
)
2067 basic_block test_bb
= ce_info
->test_bb
; /* last test block */
2068 basic_block then_bb
= ce_info
->then_bb
; /* THEN */
2069 basic_block else_bb
= ce_info
->else_bb
; /* ELSE or NULL */
2070 basic_block join_bb
= ce_info
->join_bb
; /* join block */
2071 basic_block combo_bb
;
2073 /* All block merging is done into the lower block numbers. */
2077 /* Merge any basic blocks to handle && and || subtests. Each of
2078 the blocks are on the fallthru path from the predecessor block. */
2079 if (ce_info
->num_multiple_test_blocks
> 0)
2081 basic_block bb
= test_bb
;
2082 basic_block last_test_bb
= ce_info
->last_test_bb
;
2083 basic_block fallthru
= block_fallthru (bb
);
2088 fallthru
= block_fallthru (bb
);
2089 if (post_dominators
)
2090 delete_from_dominance_info (post_dominators
, bb
);
2091 merge_blocks (combo_bb
, bb
);
2094 while (bb
!= last_test_bb
);
2097 /* Merge TEST block into THEN block. Normally the THEN block won't have a
2098 label, but it might if there were || tests. That label's count should be
2099 zero, and it normally should be removed. */
2103 if (combo_bb
->global_live_at_end
)
2104 COPY_REG_SET (combo_bb
->global_live_at_end
,
2105 then_bb
->global_live_at_end
);
2106 if (post_dominators
)
2107 delete_from_dominance_info (post_dominators
, then_bb
);
2108 merge_blocks (combo_bb
, then_bb
);
2112 /* The ELSE block, if it existed, had a label. That label count
2113 will almost always be zero, but odd things can happen when labels
2114 get their addresses taken. */
2117 if (post_dominators
)
2118 delete_from_dominance_info (post_dominators
, else_bb
);
2119 merge_blocks (combo_bb
, else_bb
);
2123 /* If there was no join block reported, that means it was not adjacent
2124 to the others, and so we cannot merge them. */
2128 rtx last
= BB_END (combo_bb
);
2130 /* The outgoing edge for the current COMBO block should already
2131 be correct. Verify this. */
2132 if (combo_bb
->succ
== NULL_EDGE
)
2134 if (find_reg_note (last
, REG_NORETURN
, NULL
))
2136 else if (GET_CODE (last
) == INSN
2137 && GET_CODE (PATTERN (last
)) == TRAP_IF
2138 && TRAP_CONDITION (PATTERN (last
)) == const_true_rtx
)
2144 /* There should still be something at the end of the THEN or ELSE
2145 blocks taking us to our final destination. */
2146 else if (GET_CODE (last
) == JUMP_INSN
)
2148 else if (combo_bb
->succ
->dest
== EXIT_BLOCK_PTR
2149 && GET_CODE (last
) == CALL_INSN
2150 && SIBLING_CALL_P (last
))
2152 else if ((combo_bb
->succ
->flags
& EDGE_EH
)
2153 && can_throw_internal (last
))
2159 /* The JOIN block may have had quite a number of other predecessors too.
2160 Since we've already merged the TEST, THEN and ELSE blocks, we should
2161 have only one remaining edge from our if-then-else diamond. If there
2162 is more than one remaining edge, it must come from elsewhere. There
2163 may be zero incoming edges if the THEN block didn't actually join
2164 back up (as with a call to abort). */
2165 else if ((join_bb
->pred
== NULL
2166 || join_bb
->pred
->pred_next
== NULL
)
2167 && join_bb
!= EXIT_BLOCK_PTR
)
2169 /* We can merge the JOIN. */
2170 if (combo_bb
->global_live_at_end
)
2171 COPY_REG_SET (combo_bb
->global_live_at_end
,
2172 join_bb
->global_live_at_end
);
2174 if (post_dominators
)
2175 delete_from_dominance_info (post_dominators
, join_bb
);
2176 merge_blocks (combo_bb
, join_bb
);
2181 /* We cannot merge the JOIN. */
2183 /* The outgoing edge for the current COMBO block should already
2184 be correct. Verify this. */
2185 if (combo_bb
->succ
->succ_next
!= NULL_EDGE
2186 || combo_bb
->succ
->dest
!= join_bb
)
2189 /* Remove the jump and cruft from the end of the COMBO block. */
2190 if (join_bb
!= EXIT_BLOCK_PTR
)
2191 tidy_fallthru_edge (combo_bb
->succ
, combo_bb
, join_bb
);
2194 num_updated_if_blocks
++;
2197 /* Find a block ending in a simple IF condition and try to transform it
2198 in some way. When converting a multi-block condition, put the new code
2199 in the first such block and delete the rest. Return a pointer to this
2200 first block if some transformation was done. Return NULL otherwise. */
2203 find_if_header (basic_block test_bb
, int pass
)
2205 ce_if_block_t ce_info
;
2209 /* The kind of block we're looking for has exactly two successors. */
2210 if ((then_edge
= test_bb
->succ
) == NULL_EDGE
2211 || (else_edge
= then_edge
->succ_next
) == NULL_EDGE
2212 || else_edge
->succ_next
!= NULL_EDGE
)
2215 /* Neither edge should be abnormal. */
2216 if ((then_edge
->flags
& EDGE_COMPLEX
)
2217 || (else_edge
->flags
& EDGE_COMPLEX
))
2220 /* Nor exit the loop. */
2221 if ((then_edge
->flags
& EDGE_LOOP_EXIT
)
2222 || (else_edge
->flags
& EDGE_LOOP_EXIT
))
2225 /* The THEN edge is canonically the one that falls through. */
2226 if (then_edge
->flags
& EDGE_FALLTHRU
)
2228 else if (else_edge
->flags
& EDGE_FALLTHRU
)
2231 else_edge
= then_edge
;
2235 /* Otherwise this must be a multiway branch of some sort. */
2238 memset (&ce_info
, '\0', sizeof (ce_info
));
2239 ce_info
.test_bb
= test_bb
;
2240 ce_info
.then_bb
= then_edge
->dest
;
2241 ce_info
.else_bb
= else_edge
->dest
;
2242 ce_info
.pass
= pass
;
2244 #ifdef IFCVT_INIT_EXTRA_FIELDS
2245 IFCVT_INIT_EXTRA_FIELDS (&ce_info
);
2248 if (find_if_block (&ce_info
))
2251 if (HAVE_trap
&& HAVE_conditional_trap
2252 && find_cond_trap (test_bb
, then_edge
, else_edge
))
2256 && (! HAVE_conditional_execution
|| reload_completed
))
2258 if (find_if_case_1 (test_bb
, then_edge
, else_edge
))
2260 if (find_if_case_2 (test_bb
, then_edge
, else_edge
))
2268 fprintf (rtl_dump_file
, "Conversion succeeded on pass %d.\n", pass
);
2269 return ce_info
.test_bb
;
2272 /* Return true if a block has two edges, one of which falls through to the next
2273 block, and the other jumps to a specific block, so that we can tell if the
2274 block is part of an && test or an || test. Returns either -1 or the number
2275 of non-note, non-jump, non-USE/CLOBBER insns in the block. */
2278 block_jumps_and_fallthru_p (basic_block cur_bb
, basic_block target_bb
)
2281 int fallthru_p
= FALSE
;
2287 if (!cur_bb
|| !target_bb
)
2290 /* If no edges, obviously it doesn't jump or fallthru. */
2291 if (cur_bb
->succ
== NULL_EDGE
)
2294 for (cur_edge
= cur_bb
->succ
;
2295 cur_edge
!= NULL_EDGE
;
2296 cur_edge
= cur_edge
->succ_next
)
2298 if (cur_edge
->flags
& EDGE_COMPLEX
)
2299 /* Anything complex isn't what we want. */
2302 else if (cur_edge
->flags
& EDGE_FALLTHRU
)
2305 else if (cur_edge
->dest
== target_bb
)
2312 if ((jump_p
& fallthru_p
) == 0)
2315 /* Don't allow calls in the block, since this is used to group && and ||
2316 together for conditional execution support. ??? we should support
2317 conditional execution support across calls for IA-64 some day, but
2318 for now it makes the code simpler. */
2319 end
= BB_END (cur_bb
);
2320 insn
= BB_HEAD (cur_bb
);
2322 while (insn
!= NULL_RTX
)
2324 if (GET_CODE (insn
) == CALL_INSN
)
2328 && GET_CODE (insn
) != JUMP_INSN
2329 && GET_CODE (PATTERN (insn
)) != USE
2330 && GET_CODE (PATTERN (insn
)) != CLOBBER
)
2336 insn
= NEXT_INSN (insn
);
2342 /* Determine if a given basic block heads a simple IF-THEN or IF-THEN-ELSE
2343 block. If so, we'll try to convert the insns to not require the branch.
2344 Return TRUE if we were successful at converting the block. */
2347 find_if_block (struct ce_if_block
* ce_info
)
2349 basic_block test_bb
= ce_info
->test_bb
;
2350 basic_block then_bb
= ce_info
->then_bb
;
2351 basic_block else_bb
= ce_info
->else_bb
;
2352 basic_block join_bb
= NULL_BLOCK
;
2353 edge then_succ
= then_bb
->succ
;
2354 edge else_succ
= else_bb
->succ
;
2355 int then_predecessors
;
2356 int else_predecessors
;
2360 ce_info
->last_test_bb
= test_bb
;
2362 /* Discover if any fall through predecessors of the current test basic block
2363 were && tests (which jump to the else block) or || tests (which jump to
2365 if (HAVE_conditional_execution
&& reload_completed
2366 && test_bb
->pred
!= NULL_EDGE
2367 && test_bb
->pred
->pred_next
== NULL_EDGE
2368 && test_bb
->pred
->flags
== EDGE_FALLTHRU
)
2370 basic_block bb
= test_bb
->pred
->src
;
2371 basic_block target_bb
;
2372 int max_insns
= MAX_CONDITIONAL_EXECUTE
;
2375 /* Determine if the preceding block is an && or || block. */
2376 if ((n_insns
= block_jumps_and_fallthru_p (bb
, else_bb
)) >= 0)
2378 ce_info
->and_and_p
= TRUE
;
2379 target_bb
= else_bb
;
2381 else if ((n_insns
= block_jumps_and_fallthru_p (bb
, then_bb
)) >= 0)
2383 ce_info
->and_and_p
= FALSE
;
2384 target_bb
= then_bb
;
2387 target_bb
= NULL_BLOCK
;
2389 if (target_bb
&& n_insns
<= max_insns
)
2391 int total_insns
= 0;
2394 ce_info
->last_test_bb
= test_bb
;
2396 /* Found at least one && or || block, look for more. */
2399 ce_info
->test_bb
= test_bb
= bb
;
2400 total_insns
+= n_insns
;
2403 if (bb
->pred
== NULL_EDGE
|| bb
->pred
->pred_next
!= NULL_EDGE
)
2407 n_insns
= block_jumps_and_fallthru_p (bb
, target_bb
);
2409 while (n_insns
>= 0 && (total_insns
+ n_insns
) <= max_insns
);
2411 ce_info
->num_multiple_test_blocks
= blocks
;
2412 ce_info
->num_multiple_test_insns
= total_insns
;
2414 if (ce_info
->and_and_p
)
2415 ce_info
->num_and_and_blocks
= blocks
;
2417 ce_info
->num_or_or_blocks
= blocks
;
2421 /* Count the number of edges the THEN and ELSE blocks have. */
2422 then_predecessors
= 0;
2423 for (cur_edge
= then_bb
->pred
;
2424 cur_edge
!= NULL_EDGE
;
2425 cur_edge
= cur_edge
->pred_next
)
2427 then_predecessors
++;
2428 if (cur_edge
->flags
& EDGE_COMPLEX
)
2432 else_predecessors
= 0;
2433 for (cur_edge
= else_bb
->pred
;
2434 cur_edge
!= NULL_EDGE
;
2435 cur_edge
= cur_edge
->pred_next
)
2437 else_predecessors
++;
2438 if (cur_edge
->flags
& EDGE_COMPLEX
)
2442 /* The THEN block of an IF-THEN combo must have exactly one predecessor,
2443 other than any || blocks which jump to the THEN block. */
2444 if ((then_predecessors
- ce_info
->num_or_or_blocks
) != 1)
2447 /* The THEN block of an IF-THEN combo must have zero or one successors. */
2448 if (then_succ
!= NULL_EDGE
2449 && (then_succ
->succ_next
!= NULL_EDGE
2450 || (then_succ
->flags
& EDGE_COMPLEX
)
2451 || (flow2_completed
&& tablejump_p (BB_END (then_bb
), NULL
, NULL
))))
2454 /* If the THEN block has no successors, conditional execution can still
2455 make a conditional call. Don't do this unless the ELSE block has
2456 only one incoming edge -- the CFG manipulation is too ugly otherwise.
2457 Check for the last insn of the THEN block being an indirect jump, which
2458 is listed as not having any successors, but confuses the rest of the CE
2459 code processing. ??? we should fix this in the future. */
2460 if (then_succ
== NULL
)
2462 if (else_bb
->pred
->pred_next
== NULL_EDGE
)
2464 rtx last_insn
= BB_END (then_bb
);
2467 && GET_CODE (last_insn
) == NOTE
2468 && last_insn
!= BB_HEAD (then_bb
))
2469 last_insn
= PREV_INSN (last_insn
);
2472 && GET_CODE (last_insn
) == JUMP_INSN
2473 && ! simplejump_p (last_insn
))
2477 else_bb
= NULL_BLOCK
;
2483 /* If the THEN block's successor is the other edge out of the TEST block,
2484 then we have an IF-THEN combo without an ELSE. */
2485 else if (then_succ
->dest
== else_bb
)
2488 else_bb
= NULL_BLOCK
;
2491 /* If the THEN and ELSE block meet in a subsequent block, and the ELSE
2492 has exactly one predecessor and one successor, and the outgoing edge
2493 is not complex, then we have an IF-THEN-ELSE combo. */
2494 else if (else_succ
!= NULL_EDGE
2495 && then_succ
->dest
== else_succ
->dest
2496 && else_bb
->pred
->pred_next
== NULL_EDGE
2497 && else_succ
->succ_next
== NULL_EDGE
2498 && ! (else_succ
->flags
& EDGE_COMPLEX
)
2499 && ! (flow2_completed
&& tablejump_p (BB_END (else_bb
), NULL
, NULL
)))
2500 join_bb
= else_succ
->dest
;
2502 /* Otherwise it is not an IF-THEN or IF-THEN-ELSE combination. */
2506 num_possible_if_blocks
++;
2510 fprintf (rtl_dump_file
, "\nIF-THEN%s block found, pass %d, start block %d [insn %d], then %d [%d]",
2511 (else_bb
) ? "-ELSE" : "",
2513 test_bb
->index
, (BB_HEAD (test_bb
)) ? (int)INSN_UID (BB_HEAD (test_bb
)) : -1,
2514 then_bb
->index
, (BB_HEAD (then_bb
)) ? (int)INSN_UID (BB_HEAD (then_bb
)) : -1);
2517 fprintf (rtl_dump_file
, ", else %d [%d]",
2518 else_bb
->index
, (BB_HEAD (else_bb
)) ? (int)INSN_UID (BB_HEAD (else_bb
)) : -1);
2520 fprintf (rtl_dump_file
, ", join %d [%d]",
2521 join_bb
->index
, (BB_HEAD (join_bb
)) ? (int)INSN_UID (BB_HEAD (join_bb
)) : -1);
2523 if (ce_info
->num_multiple_test_blocks
> 0)
2524 fprintf (rtl_dump_file
, ", %d %s block%s last test %d [%d]",
2525 ce_info
->num_multiple_test_blocks
,
2526 (ce_info
->and_and_p
) ? "&&" : "||",
2527 (ce_info
->num_multiple_test_blocks
== 1) ? "" : "s",
2528 ce_info
->last_test_bb
->index
,
2529 ((BB_HEAD (ce_info
->last_test_bb
))
2530 ? (int)INSN_UID (BB_HEAD (ce_info
->last_test_bb
))
2533 fputc ('\n', rtl_dump_file
);
2536 /* Make sure IF, THEN, and ELSE, blocks are adjacent. Actually, we get the
2537 first condition for free, since we've already asserted that there's a
2538 fallthru edge from IF to THEN. Likewise for the && and || blocks, since
2539 we checked the FALLTHRU flag, those are already adjacent to the last IF
2541 /* ??? As an enhancement, move the ELSE block. Have to deal with
2542 BLOCK notes, if by no other means than aborting the merge if they
2543 exist. Sticky enough I don't want to think about it now. */
2545 if (else_bb
&& (next
= next
->next_bb
) != else_bb
)
2547 if ((next
= next
->next_bb
) != join_bb
&& join_bb
!= EXIT_BLOCK_PTR
)
2555 /* Do the real work. */
2556 ce_info
->else_bb
= else_bb
;
2557 ce_info
->join_bb
= join_bb
;
2559 return process_if_block (ce_info
);
2562 /* Convert a branch over a trap, or a branch
2563 to a trap, into a conditional trap. */
2566 find_cond_trap (basic_block test_bb
, edge then_edge
, edge else_edge
)
2568 basic_block then_bb
= then_edge
->dest
;
2569 basic_block else_bb
= else_edge
->dest
;
2570 basic_block other_bb
, trap_bb
;
2571 rtx trap
, jump
, cond
, cond_earliest
, seq
;
2574 /* Locate the block with the trap instruction. */
2575 /* ??? While we look for no successors, we really ought to allow
2576 EH successors. Need to fix merge_if_block for that to work. */
2577 if ((trap
= block_has_only_trap (then_bb
)) != NULL
)
2578 trap_bb
= then_bb
, other_bb
= else_bb
;
2579 else if ((trap
= block_has_only_trap (else_bb
)) != NULL
)
2580 trap_bb
= else_bb
, other_bb
= then_bb
;
2586 fprintf (rtl_dump_file
, "\nTRAP-IF block found, start %d, trap %d\n",
2587 test_bb
->index
, trap_bb
->index
);
2590 /* If this is not a standard conditional jump, we can't parse it. */
2591 jump
= BB_END (test_bb
);
2592 cond
= noce_get_condition (jump
, &cond_earliest
);
2596 /* If the conditional jump is more than just a conditional jump, then
2597 we can not do if-conversion on this block. */
2598 if (! onlyjump_p (jump
))
2601 /* We must be comparing objects whose modes imply the size. */
2602 if (GET_MODE (XEXP (cond
, 0)) == BLKmode
)
2605 /* Reverse the comparison code, if necessary. */
2606 code
= GET_CODE (cond
);
2607 if (then_bb
== trap_bb
)
2609 code
= reversed_comparison_code (cond
, jump
);
2610 if (code
== UNKNOWN
)
2614 /* Attempt to generate the conditional trap. */
2615 seq
= gen_cond_trap (code
, XEXP (cond
, 0),
2617 TRAP_CODE (PATTERN (trap
)));
2623 /* Emit the new insns before cond_earliest. */
2624 emit_insn_before_setloc (seq
, cond_earliest
, INSN_LOCATOR (trap
));
2626 /* Delete the trap block if possible. */
2627 remove_edge (trap_bb
== then_bb
? then_edge
: else_edge
);
2628 if (trap_bb
->pred
== NULL
)
2630 if (post_dominators
)
2631 delete_from_dominance_info (post_dominators
, trap_bb
);
2632 delete_block (trap_bb
);
2635 /* If the non-trap block and the test are now adjacent, merge them.
2636 Otherwise we must insert a direct branch. */
2637 if (test_bb
->next_bb
== other_bb
)
2639 struct ce_if_block new_ce_info
;
2641 memset (&new_ce_info
, '\0', sizeof (new_ce_info
));
2642 new_ce_info
.test_bb
= test_bb
;
2643 new_ce_info
.then_bb
= NULL
;
2644 new_ce_info
.else_bb
= NULL
;
2645 new_ce_info
.join_bb
= other_bb
;
2646 merge_if_block (&new_ce_info
);
2652 lab
= JUMP_LABEL (jump
);
2653 newjump
= emit_jump_insn_after (gen_jump (lab
), jump
);
2654 LABEL_NUSES (lab
) += 1;
2655 JUMP_LABEL (newjump
) = lab
;
2656 emit_barrier_after (newjump
);
2664 /* Subroutine of find_cond_trap: if BB contains only a trap insn,
2668 block_has_only_trap (basic_block bb
)
2672 /* We're not the exit block. */
2673 if (bb
== EXIT_BLOCK_PTR
)
2676 /* The block must have no successors. */
2680 /* The only instruction in the THEN block must be the trap. */
2681 trap
= first_active_insn (bb
);
2682 if (! (trap
== BB_END (bb
)
2683 && GET_CODE (PATTERN (trap
)) == TRAP_IF
2684 && TRAP_CONDITION (PATTERN (trap
)) == const_true_rtx
))
2690 /* Look for IF-THEN-ELSE cases in which one of THEN or ELSE is
2691 transformable, but not necessarily the other. There need be no
2694 Return TRUE if we were successful at converting the block.
2696 Cases we'd like to look at:
2699 if (test) goto over; // x not live
2707 if (! test) goto label;
2710 if (test) goto E; // x not live
2724 (3) // This one's really only interesting for targets that can do
2725 // multiway branching, e.g. IA-64 BBB bundles. For other targets
2726 // it results in multiple branches on a cache line, which often
2727 // does not sit well with predictors.
2729 if (test1) goto E; // predicted not taken
2745 (A) Don't do (2) if the branch is predicted against the block we're
2746 eliminating. Do it anyway if we can eliminate a branch; this requires
2747 that the sole successor of the eliminated block postdominate the other
2750 (B) With CE, on (3) we can steal from both sides of the if, creating
2759 Again, this is most useful if J postdominates.
2761 (C) CE substitutes for helpful life information.
2763 (D) These heuristics need a lot of work. */
2765 /* Tests for case 1 above. */
2768 find_if_case_1 (basic_block test_bb
, edge then_edge
, edge else_edge
)
2770 basic_block then_bb
= then_edge
->dest
;
2771 basic_block else_bb
= else_edge
->dest
, new_bb
;
2772 edge then_succ
= then_bb
->succ
;
2775 /* THEN has one successor. */
2776 if (!then_succ
|| then_succ
->succ_next
!= NULL
)
2779 /* THEN does not fall through, but is not strange either. */
2780 if (then_succ
->flags
& (EDGE_COMPLEX
| EDGE_FALLTHRU
))
2783 /* THEN has one predecessor. */
2784 if (then_bb
->pred
->pred_next
!= NULL
)
2787 /* THEN must do something. */
2788 if (forwarder_block_p (then_bb
))
2791 num_possible_if_blocks
++;
2793 fprintf (rtl_dump_file
,
2794 "\nIF-CASE-1 found, start %d, then %d\n",
2795 test_bb
->index
, then_bb
->index
);
2797 /* THEN is small. */
2798 if (count_bb_insns (then_bb
) > BRANCH_COST
)
2801 /* Registers set are dead, or are predicable. */
2802 if (! dead_or_predicable (test_bb
, then_bb
, else_bb
,
2803 then_bb
->succ
->dest
, 1))
2806 /* Conversion went ok, including moving the insns and fixing up the
2807 jump. Adjust the CFG to match. */
2809 bitmap_operation (test_bb
->global_live_at_end
,
2810 else_bb
->global_live_at_start
,
2811 then_bb
->global_live_at_end
, BITMAP_IOR
);
2813 new_bb
= redirect_edge_and_branch_force (FALLTHRU_EDGE (test_bb
), else_bb
);
2814 then_bb_index
= then_bb
->index
;
2815 if (post_dominators
)
2816 delete_from_dominance_info (post_dominators
, then_bb
);
2817 delete_block (then_bb
);
2819 /* Make rest of code believe that the newly created block is the THEN_BB
2820 block we removed. */
2823 new_bb
->index
= then_bb_index
;
2824 BASIC_BLOCK (then_bb_index
) = new_bb
;
2825 if (post_dominators
)
2826 add_to_dominance_info (post_dominators
, new_bb
);
2828 /* We've possibly created jump to next insn, cleanup_cfg will solve that
2832 num_updated_if_blocks
++;
2837 /* Test for case 2 above. */
2840 find_if_case_2 (basic_block test_bb
, edge then_edge
, edge else_edge
)
2842 basic_block then_bb
= then_edge
->dest
;
2843 basic_block else_bb
= else_edge
->dest
;
2844 edge else_succ
= else_bb
->succ
;
2847 /* ELSE has one successor. */
2848 if (!else_succ
|| else_succ
->succ_next
!= NULL
)
2851 /* ELSE outgoing edge is not complex. */
2852 if (else_succ
->flags
& EDGE_COMPLEX
)
2855 /* ELSE has one predecessor. */
2856 if (else_bb
->pred
->pred_next
!= NULL
)
2859 /* THEN is not EXIT. */
2860 if (then_bb
->index
< 0)
2863 /* ELSE is predicted or SUCC(ELSE) postdominates THEN. */
2864 note
= find_reg_note (BB_END (test_bb
), REG_BR_PROB
, NULL_RTX
);
2865 if (note
&& INTVAL (XEXP (note
, 0)) >= REG_BR_PROB_BASE
/ 2)
2867 else if (else_succ
->dest
->index
< 0
2868 || dominated_by_p (post_dominators
, then_bb
,
2874 num_possible_if_blocks
++;
2876 fprintf (rtl_dump_file
,
2877 "\nIF-CASE-2 found, start %d, else %d\n",
2878 test_bb
->index
, else_bb
->index
);
2880 /* ELSE is small. */
2881 if (count_bb_insns (else_bb
) > BRANCH_COST
)
2884 /* Registers set are dead, or are predicable. */
2885 if (! dead_or_predicable (test_bb
, else_bb
, then_bb
, else_succ
->dest
, 0))
2888 /* Conversion went ok, including moving the insns and fixing up the
2889 jump. Adjust the CFG to match. */
2891 bitmap_operation (test_bb
->global_live_at_end
,
2892 then_bb
->global_live_at_start
,
2893 else_bb
->global_live_at_end
, BITMAP_IOR
);
2895 if (post_dominators
)
2896 delete_from_dominance_info (post_dominators
, else_bb
);
2897 delete_block (else_bb
);
2900 num_updated_if_blocks
++;
2902 /* ??? We may now fallthru from one of THEN's successors into a join
2903 block. Rerun cleanup_cfg? Examine things manually? Wait? */
2908 /* A subroutine of dead_or_predicable called through for_each_rtx.
2909 Return 1 if a memory is found. */
2912 find_memory (rtx
*px
, void *data ATTRIBUTE_UNUSED
)
2914 return GET_CODE (*px
) == MEM
;
2917 /* Used by the code above to perform the actual rtl transformations.
2918 Return TRUE if successful.
2920 TEST_BB is the block containing the conditional branch. MERGE_BB
2921 is the block containing the code to manipulate. NEW_DEST is the
2922 label TEST_BB should be branching to after the conversion.
2923 REVERSEP is true if the sense of the branch should be reversed. */
2926 dead_or_predicable (basic_block test_bb
, basic_block merge_bb
,
2927 basic_block other_bb
, basic_block new_dest
, int reversep
)
2929 rtx head
, end
, jump
, earliest
, old_dest
, new_label
= NULL_RTX
;
2931 jump
= BB_END (test_bb
);
2933 /* Find the extent of the real code in the merge block. */
2934 head
= BB_HEAD (merge_bb
);
2935 end
= BB_END (merge_bb
);
2937 if (GET_CODE (head
) == CODE_LABEL
)
2938 head
= NEXT_INSN (head
);
2939 if (GET_CODE (head
) == NOTE
)
2943 head
= end
= NULL_RTX
;
2946 head
= NEXT_INSN (head
);
2949 if (GET_CODE (end
) == JUMP_INSN
)
2953 head
= end
= NULL_RTX
;
2956 end
= PREV_INSN (end
);
2959 /* Disable handling dead code by conditional execution if the machine needs
2960 to do anything funny with the tests, etc. */
2961 #ifndef IFCVT_MODIFY_TESTS
2962 if (HAVE_conditional_execution
)
2964 /* In the conditional execution case, we have things easy. We know
2965 the condition is reversible. We don't have to check life info
2966 because we're going to conditionally execute the code anyway.
2967 All that's left is making sure the insns involved can actually
2972 cond
= cond_exec_get_condition (jump
);
2976 prob_val
= find_reg_note (jump
, REG_BR_PROB
, NULL_RTX
);
2978 prob_val
= XEXP (prob_val
, 0);
2982 enum rtx_code rev
= reversed_comparison_code (cond
, jump
);
2985 cond
= gen_rtx_fmt_ee (rev
, GET_MODE (cond
), XEXP (cond
, 0),
2988 prob_val
= GEN_INT (REG_BR_PROB_BASE
- INTVAL (prob_val
));
2991 if (! cond_exec_process_insns ((ce_if_block_t
*)0, head
, end
, cond
,
3000 /* In the non-conditional execution case, we have to verify that there
3001 are no trapping operations, no calls, no references to memory, and
3002 that any registers modified are dead at the branch site. */
3004 rtx insn
, cond
, prev
;
3005 regset_head merge_set_head
, tmp_head
, test_live_head
, test_set_head
;
3006 regset merge_set
, tmp
, test_live
, test_set
;
3007 struct propagate_block_info
*pbi
;
3010 /* Check for no calls or trapping operations. */
3011 for (insn
= head
; ; insn
= NEXT_INSN (insn
))
3013 if (GET_CODE (insn
) == CALL_INSN
)
3017 if (may_trap_p (PATTERN (insn
)))
3020 /* ??? Even non-trapping memories such as stack frame
3021 references must be avoided. For stores, we collect
3022 no lifetime info; for reads, we'd have to assert
3023 true_dependence false against every store in the
3025 if (for_each_rtx (&PATTERN (insn
), find_memory
, NULL
))
3032 if (! any_condjump_p (jump
))
3035 /* Find the extent of the conditional. */
3036 cond
= noce_get_condition (jump
, &earliest
);
3041 MERGE_SET = set of registers set in MERGE_BB
3042 TEST_LIVE = set of registers live at EARLIEST
3043 TEST_SET = set of registers set between EARLIEST and the
3044 end of the block. */
3046 tmp
= INITIALIZE_REG_SET (tmp_head
);
3047 merge_set
= INITIALIZE_REG_SET (merge_set_head
);
3048 test_live
= INITIALIZE_REG_SET (test_live_head
);
3049 test_set
= INITIALIZE_REG_SET (test_set_head
);
3051 /* ??? bb->local_set is only valid during calculate_global_regs_live,
3052 so we must recompute usage for MERGE_BB. Not so bad, I suppose,
3053 since we've already asserted that MERGE_BB is small. */
3054 propagate_block (merge_bb
, tmp
, merge_set
, merge_set
, 0);
3056 /* For small register class machines, don't lengthen lifetimes of
3057 hard registers before reload. */
3058 if (SMALL_REGISTER_CLASSES
&& ! reload_completed
)
3060 EXECUTE_IF_SET_IN_BITMAP
3063 if (i
< FIRST_PSEUDO_REGISTER
3065 && ! global_regs
[i
])
3070 /* For TEST, we're interested in a range of insns, not a whole block.
3071 Moreover, we're interested in the insns live from OTHER_BB. */
3073 COPY_REG_SET (test_live
, other_bb
->global_live_at_start
);
3074 pbi
= init_propagate_block_info (test_bb
, test_live
, test_set
, test_set
,
3077 for (insn
= jump
; ; insn
= prev
)
3079 prev
= propagate_one_insn (pbi
, insn
);
3080 if (insn
== earliest
)
3084 free_propagate_block_info (pbi
);
3086 /* We can perform the transformation if
3087 MERGE_SET & (TEST_SET | TEST_LIVE)
3089 TEST_SET & merge_bb->global_live_at_start
3092 bitmap_operation (tmp
, test_set
, test_live
, BITMAP_IOR
);
3093 bitmap_operation (tmp
, tmp
, merge_set
, BITMAP_AND
);
3094 EXECUTE_IF_SET_IN_BITMAP(tmp
, 0, i
, fail
= 1);
3096 bitmap_operation (tmp
, test_set
, merge_bb
->global_live_at_start
,
3098 EXECUTE_IF_SET_IN_BITMAP(tmp
, 0, i
, fail
= 1);
3101 FREE_REG_SET (merge_set
);
3102 FREE_REG_SET (test_live
);
3103 FREE_REG_SET (test_set
);
3110 /* We don't want to use normal invert_jump or redirect_jump because
3111 we don't want to delete_insn called. Also, we want to do our own
3112 change group management. */
3114 old_dest
= JUMP_LABEL (jump
);
3115 if (other_bb
!= new_dest
)
3117 new_label
= block_label (new_dest
);
3119 ? ! invert_jump_1 (jump
, new_label
)
3120 : ! redirect_jump_1 (jump
, new_label
))
3124 if (! apply_change_group ())
3127 if (other_bb
!= new_dest
)
3130 LABEL_NUSES (old_dest
) -= 1;
3132 LABEL_NUSES (new_label
) += 1;
3133 JUMP_LABEL (jump
) = new_label
;
3135 invert_br_probabilities (jump
);
3137 redirect_edge_succ (BRANCH_EDGE (test_bb
), new_dest
);
3140 gcov_type count
, probability
;
3141 count
= BRANCH_EDGE (test_bb
)->count
;
3142 BRANCH_EDGE (test_bb
)->count
= FALLTHRU_EDGE (test_bb
)->count
;
3143 FALLTHRU_EDGE (test_bb
)->count
= count
;
3144 probability
= BRANCH_EDGE (test_bb
)->probability
;
3145 BRANCH_EDGE (test_bb
)->probability
3146 = FALLTHRU_EDGE (test_bb
)->probability
;
3147 FALLTHRU_EDGE (test_bb
)->probability
= probability
;
3148 update_br_prob_note (test_bb
);
3152 /* Move the insns out of MERGE_BB to before the branch. */
3155 if (end
== BB_END (merge_bb
))
3156 BB_END (merge_bb
) = PREV_INSN (head
);
3158 if (squeeze_notes (&head
, &end
))
3161 reorder_insns (head
, end
, PREV_INSN (earliest
));
3164 /* Remove the jump and edge if we can. */
3165 if (other_bb
== new_dest
)
3168 remove_edge (BRANCH_EDGE (test_bb
));
3169 /* ??? Can't merge blocks here, as then_bb is still in use.
3170 At minimum, the merge will get done just before bb-reorder. */
3180 /* Main entry point for all if-conversion. */
3183 if_convert (int x_life_data_ok
)
3188 num_possible_if_blocks
= 0;
3189 num_updated_if_blocks
= 0;
3190 num_true_changes
= 0;
3191 life_data_ok
= (x_life_data_ok
!= 0);
3193 if (! (* targetm
.cannot_modify_jumps_p
) ())
3194 mark_loop_exit_edges ();
3196 /* Free up basic_block_for_insn so that we don't have to keep it
3197 up to date, either here or in merge_blocks. */
3198 free_basic_block_vars (1);
3200 /* Compute postdominators if we think we'll use them. */
3201 post_dominators
= NULL
;
3202 if (HAVE_conditional_execution
|| life_data_ok
)
3204 post_dominators
= calculate_dominance_info (CDI_POST_DOMINATORS
);
3209 /* Go through each of the basic blocks looking for things to convert. If we
3210 have conditional execution, we make multiple passes to allow us to handle
3211 IF-THEN{-ELSE} blocks within other IF-THEN{-ELSE} blocks. */
3215 cond_exec_changed_p
= FALSE
;
3218 #ifdef IFCVT_MULTIPLE_DUMPS
3219 if (rtl_dump_file
&& pass
> 1)
3220 fprintf (rtl_dump_file
, "\n\n========== Pass %d ==========\n", pass
);
3226 while ((new_bb
= find_if_header (bb
, pass
)))
3230 #ifdef IFCVT_MULTIPLE_DUMPS
3231 if (rtl_dump_file
&& cond_exec_changed_p
)
3232 print_rtl_with_bb (rtl_dump_file
, get_insns ());
3235 while (cond_exec_changed_p
);
3237 #ifdef IFCVT_MULTIPLE_DUMPS
3239 fprintf (rtl_dump_file
, "\n\n========== no more changes\n");
3242 if (post_dominators
)
3243 free_dominance_info (post_dominators
);
3246 fflush (rtl_dump_file
);
3248 clear_aux_for_blocks ();
3250 /* Rebuild life info for basic blocks that require it. */
3251 if (num_true_changes
&& life_data_ok
)
3253 /* If we allocated new pseudos, we must resize the array for sched1. */
3254 if (max_regno
< max_reg_num ())
3256 max_regno
= max_reg_num ();
3257 allocate_reg_info (max_regno
, FALSE
, FALSE
);
3259 update_life_info_in_dirty_blocks (UPDATE_LIFE_GLOBAL_RM_NOTES
,
3260 PROP_DEATH_NOTES
| PROP_SCAN_DEAD_CODE
3261 | PROP_KILL_DEAD_CODE
);
3264 /* Write the final stats. */
3265 if (rtl_dump_file
&& num_possible_if_blocks
> 0)
3267 fprintf (rtl_dump_file
,
3268 "\n%d possible IF blocks searched.\n",
3269 num_possible_if_blocks
);
3270 fprintf (rtl_dump_file
,
3271 "%d IF blocks converted.\n",
3272 num_updated_if_blocks
);
3273 fprintf (rtl_dump_file
,
3274 "%d true changes made.\n\n\n",
3278 #ifdef ENABLE_CHECKING
3279 verify_flow_info ();