1 /* If-conversion support.
2 Copyright (C) 2000, 2001, 2002 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"
42 #ifndef HAVE_conditional_execution
43 #define HAVE_conditional_execution 0
45 #ifndef HAVE_conditional_move
46 #define HAVE_conditional_move 0
57 #ifndef HAVE_conditional_trap
58 #define HAVE_conditional_trap 0
61 #ifndef MAX_CONDITIONAL_EXECUTE
62 #define MAX_CONDITIONAL_EXECUTE (BRANCH_COST + 1)
65 #define NULL_EDGE ((struct edge_def *)NULL)
66 #define NULL_BLOCK ((struct basic_block_def *)NULL)
68 /* # of IF-THEN or IF-THEN-ELSE blocks we looked at */
69 static int num_possible_if_blocks
;
71 /* # of IF-THEN or IF-THEN-ELSE blocks were converted to conditional
73 static int num_updated_if_blocks
;
75 /* # of basic blocks that were removed. */
76 static int num_removed_blocks
;
78 /* Whether conditional execution changes were made. */
79 static int cond_exec_changed_p
;
81 /* True if life data ok at present. */
82 static bool life_data_ok
;
84 /* The post-dominator relation on the original block numbers. */
85 static dominance_info post_dominators
;
87 /* Forward references. */
88 static int count_bb_insns
PARAMS ((basic_block
));
89 static rtx first_active_insn
PARAMS ((basic_block
));
90 static rtx last_active_insn
PARAMS ((basic_block
, int));
91 static int seq_contains_jump
PARAMS ((rtx
));
92 static basic_block block_fallthru
PARAMS ((basic_block
));
93 static int cond_exec_process_insns
PARAMS ((ce_if_block_t
*,
94 rtx
, rtx
, rtx
, rtx
, int));
95 static rtx cond_exec_get_condition
PARAMS ((rtx
));
96 static int cond_exec_process_if_block
PARAMS ((ce_if_block_t
*, int));
97 static rtx noce_get_condition
PARAMS ((rtx
, rtx
*));
98 static int noce_operand_ok
PARAMS ((rtx
));
99 static int noce_process_if_block
PARAMS ((ce_if_block_t
*));
100 static int process_if_block
PARAMS ((ce_if_block_t
*));
101 static void merge_if_block
PARAMS ((ce_if_block_t
*));
102 static int find_cond_trap
PARAMS ((basic_block
, edge
, edge
));
103 static basic_block find_if_header
PARAMS ((basic_block
, int));
104 static int block_jumps_and_fallthru_p
PARAMS ((basic_block
, basic_block
));
105 static int find_if_block
PARAMS ((ce_if_block_t
*));
106 static int find_if_case_1
PARAMS ((basic_block
, edge
, edge
));
107 static int find_if_case_2
PARAMS ((basic_block
, edge
, edge
));
108 static int find_memory
PARAMS ((rtx
*, void *));
109 static int dead_or_predicable
PARAMS ((basic_block
, basic_block
,
110 basic_block
, basic_block
, int));
111 static void noce_emit_move_insn
PARAMS ((rtx
, rtx
));
112 static rtx block_has_only_trap
PARAMS ((basic_block
));
114 /* Count the number of non-jump active insns in BB. */
125 if (GET_CODE (insn
) == CALL_INSN
|| GET_CODE (insn
) == INSN
)
130 insn
= NEXT_INSN (insn
);
136 /* Return the first non-jump active insn in the basic block. */
139 first_active_insn (bb
)
144 if (GET_CODE (insn
) == CODE_LABEL
)
148 insn
= NEXT_INSN (insn
);
151 while (GET_CODE (insn
) == NOTE
)
155 insn
= NEXT_INSN (insn
);
158 if (GET_CODE (insn
) == JUMP_INSN
)
164 /* Return the last non-jump active (non-jump) insn in the basic block. */
167 last_active_insn (bb
, skip_use_p
)
174 while (GET_CODE (insn
) == NOTE
175 || GET_CODE (insn
) == JUMP_INSN
177 && GET_CODE (insn
) == INSN
178 && GET_CODE (PATTERN (insn
)) == USE
))
182 insn
= PREV_INSN (insn
);
185 if (GET_CODE (insn
) == CODE_LABEL
)
191 /* It is possible, especially when having dealt with multi-word
192 arithmetic, for the expanders to have emitted jumps. Search
193 through the sequence and return TRUE if a jump exists so that
194 we can abort the conversion. */
197 seq_contains_jump (insn
)
202 if (GET_CODE (insn
) == JUMP_INSN
)
204 insn
= NEXT_INSN (insn
);
216 e
!= NULL_EDGE
&& (e
->flags
& EDGE_FALLTHRU
) == 0;
220 return (e
) ? e
->dest
: NULL_BLOCK
;
223 /* Go through a bunch of insns, converting them to conditional
224 execution format if possible. Return TRUE if all of the non-note
225 insns were processed. */
228 cond_exec_process_insns (ce_info
, start
, end
, test
, prob_val
, mod_ok
)
229 ce_if_block_t
*ce_info ATTRIBUTE_UNUSED
; /* if block information */
230 rtx start
; /* first insn to look at */
231 rtx end
; /* last insn to look at */
232 rtx test
; /* conditional execution test */
233 rtx prob_val
; /* probability of branch taken. */
234 int mod_ok
; /* true if modifications ok last insn. */
236 int must_be_last
= FALSE
;
244 for (insn
= start
; ; insn
= NEXT_INSN (insn
))
246 if (GET_CODE (insn
) == NOTE
)
249 if (GET_CODE (insn
) != INSN
&& GET_CODE (insn
) != CALL_INSN
)
252 /* Remove USE insns that get in the way. */
253 if (reload_completed
&& GET_CODE (PATTERN (insn
)) == USE
)
255 /* ??? Ug. Actually unlinking the thing is problematic,
256 given what we'd have to coordinate with our callers. */
257 PUT_CODE (insn
, NOTE
);
258 NOTE_LINE_NUMBER (insn
) = NOTE_INSN_DELETED
;
259 NOTE_SOURCE_FILE (insn
) = 0;
263 /* Last insn wasn't last? */
267 if (modified_in_p (test
, insn
))
274 /* Now build the conditional form of the instruction. */
275 pattern
= PATTERN (insn
);
276 xtest
= copy_rtx (test
);
278 /* If this is already a COND_EXEC, rewrite the test to be an AND of the
280 if (GET_CODE (pattern
) == COND_EXEC
)
282 if (GET_MODE (xtest
) != GET_MODE (COND_EXEC_TEST (pattern
)))
285 xtest
= gen_rtx_AND (GET_MODE (xtest
), xtest
,
286 COND_EXEC_TEST (pattern
));
287 pattern
= COND_EXEC_CODE (pattern
);
290 pattern
= gen_rtx_COND_EXEC (VOIDmode
, xtest
, pattern
);
292 /* If the machine needs to modify the insn being conditionally executed,
293 say for example to force a constant integer operand into a temp
294 register, do so here. */
295 #ifdef IFCVT_MODIFY_INSN
296 IFCVT_MODIFY_INSN (ce_info
, pattern
, insn
);
301 validate_change (insn
, &PATTERN (insn
), pattern
, 1);
303 if (GET_CODE (insn
) == CALL_INSN
&& prob_val
)
304 validate_change (insn
, ®_NOTES (insn
),
305 alloc_EXPR_LIST (REG_BR_PROB
, prob_val
,
306 REG_NOTES (insn
)), 1);
316 /* Return the condition for a jump. Do not do any special processing. */
319 cond_exec_get_condition (jump
)
324 if (any_condjump_p (jump
))
325 test_if
= SET_SRC (pc_set (jump
));
328 cond
= XEXP (test_if
, 0);
330 /* If this branches to JUMP_LABEL when the condition is false,
331 reverse the condition. */
332 if (GET_CODE (XEXP (test_if
, 2)) == LABEL_REF
333 && XEXP (XEXP (test_if
, 2), 0) == JUMP_LABEL (jump
))
335 enum rtx_code rev
= reversed_comparison_code (cond
, jump
);
339 cond
= gen_rtx_fmt_ee (rev
, GET_MODE (cond
), XEXP (cond
, 0),
346 /* Given a simple IF-THEN or IF-THEN-ELSE block, attempt to convert it
347 to conditional execution. Return TRUE if we were successful at
348 converting the block. */
351 cond_exec_process_if_block (ce_info
, do_multiple_p
)
352 ce_if_block_t
* ce_info
; /* if block information */
353 int do_multiple_p
; /* != 0 if we should handle && and || blocks */
355 basic_block test_bb
= ce_info
->test_bb
; /* last test block */
356 basic_block then_bb
= ce_info
->then_bb
; /* THEN */
357 basic_block else_bb
= ce_info
->else_bb
; /* ELSE or NULL */
358 rtx test_expr
; /* expression in IF_THEN_ELSE that is tested */
359 rtx then_start
; /* first insn in THEN block */
360 rtx then_end
; /* last insn + 1 in THEN block */
361 rtx else_start
= NULL_RTX
; /* first insn in ELSE block or NULL */
362 rtx else_end
= NULL_RTX
; /* last insn + 1 in ELSE block */
363 int max
; /* max # of insns to convert. */
364 int then_mod_ok
; /* whether conditional mods are ok in THEN */
365 rtx true_expr
; /* test for else block insns */
366 rtx false_expr
; /* test for then block insns */
367 rtx true_prob_val
; /* probability of else block */
368 rtx false_prob_val
; /* probability of then block */
370 enum rtx_code false_code
;
372 /* If test is comprised of && or || elements, and we've failed at handling
373 all of them together, just use the last test if it is the special case of
374 && elements without an ELSE block. */
375 if (!do_multiple_p
&& ce_info
->num_multiple_test_blocks
)
377 if (else_bb
|| ! ce_info
->and_and_p
)
380 ce_info
->test_bb
= test_bb
= ce_info
->last_test_bb
;
381 ce_info
->num_multiple_test_blocks
= 0;
382 ce_info
->num_and_and_blocks
= 0;
383 ce_info
->num_or_or_blocks
= 0;
386 /* Find the conditional jump to the ELSE or JOIN part, and isolate
388 test_expr
= cond_exec_get_condition (test_bb
->end
);
392 /* If the conditional jump is more than just a conditional jump,
393 then we can not do conditional execution conversion on this block. */
394 if (! onlyjump_p (test_bb
->end
))
397 /* Collect the bounds of where we're to search, skipping any labels, jumps
398 and notes at the beginning and end of the block. Then count the total
399 number of insns and see if it is small enough to convert. */
400 then_start
= first_active_insn (then_bb
);
401 then_end
= last_active_insn (then_bb
, TRUE
);
402 n_insns
= ce_info
->num_then_insns
= count_bb_insns (then_bb
);
403 max
= MAX_CONDITIONAL_EXECUTE
;
408 else_start
= first_active_insn (else_bb
);
409 else_end
= last_active_insn (else_bb
, TRUE
);
410 n_insns
+= ce_info
->num_else_insns
= count_bb_insns (else_bb
);
416 /* Map test_expr/test_jump into the appropriate MD tests to use on
417 the conditionally executed code. */
419 true_expr
= test_expr
;
421 false_code
= reversed_comparison_code (true_expr
, test_bb
->end
);
422 if (false_code
!= UNKNOWN
)
423 false_expr
= gen_rtx_fmt_ee (false_code
, GET_MODE (true_expr
),
424 XEXP (true_expr
, 0), XEXP (true_expr
, 1));
426 false_expr
= NULL_RTX
;
428 #ifdef IFCVT_MODIFY_TESTS
429 /* If the machine description needs to modify the tests, such as setting a
430 conditional execution register from a comparison, it can do so here. */
431 IFCVT_MODIFY_TESTS (ce_info
, true_expr
, false_expr
);
433 /* See if the conversion failed */
434 if (!true_expr
|| !false_expr
)
438 true_prob_val
= find_reg_note (test_bb
->end
, REG_BR_PROB
, NULL_RTX
);
441 true_prob_val
= XEXP (true_prob_val
, 0);
442 false_prob_val
= GEN_INT (REG_BR_PROB_BASE
- INTVAL (true_prob_val
));
445 false_prob_val
= NULL_RTX
;
447 /* If we have && or || tests, do them here. These tests are in the adjacent
448 blocks after the first block containing the test. */
449 if (ce_info
->num_multiple_test_blocks
> 0)
451 basic_block bb
= test_bb
;
452 basic_block last_test_bb
= ce_info
->last_test_bb
;
462 bb
= block_fallthru (bb
);
463 start
= first_active_insn (bb
);
464 end
= last_active_insn (bb
, TRUE
);
466 && ! cond_exec_process_insns (ce_info
, start
, end
, false_expr
,
467 false_prob_val
, FALSE
))
470 /* If the conditional jump is more than just a conditional jump, then
471 we can not do conditional execution conversion on this block. */
472 if (! onlyjump_p (bb
->end
))
475 /* Find the conditional jump and isolate the test. */
476 t
= cond_exec_get_condition (bb
->end
);
480 f
= gen_rtx_fmt_ee (reverse_condition (GET_CODE (t
)),
485 if (ce_info
->and_and_p
)
487 t
= gen_rtx_AND (GET_MODE (t
), true_expr
, t
);
488 f
= gen_rtx_IOR (GET_MODE (t
), false_expr
, f
);
492 t
= gen_rtx_IOR (GET_MODE (t
), true_expr
, t
);
493 f
= gen_rtx_AND (GET_MODE (t
), false_expr
, f
);
496 /* If the machine description needs to modify the tests, such as
497 setting a conditional execution register from a comparison, it can
499 #ifdef IFCVT_MODIFY_MULTIPLE_TESTS
500 IFCVT_MODIFY_MULTIPLE_TESTS (ce_info
, bb
, t
, f
);
502 /* See if the conversion failed */
510 while (bb
!= last_test_bb
);
513 /* For IF-THEN-ELSE blocks, we don't allow modifications of the test
514 on then THEN block. */
515 then_mod_ok
= (else_bb
== NULL_BLOCK
);
517 /* Go through the THEN and ELSE blocks converting the insns if possible
518 to conditional execution. */
522 || ! cond_exec_process_insns (ce_info
, then_start
, then_end
,
523 false_expr
, false_prob_val
,
527 if (else_bb
&& else_end
528 && ! cond_exec_process_insns (ce_info
, else_start
, else_end
,
529 true_expr
, true_prob_val
, TRUE
))
532 /* If we cannot apply the changes, fail. Do not go through the normal fail
533 processing, since apply_change_group will call cancel_changes. */
534 if (! apply_change_group ())
536 #ifdef IFCVT_MODIFY_CANCEL
537 /* Cancel any machine dependent changes. */
538 IFCVT_MODIFY_CANCEL (ce_info
);
543 #ifdef IFCVT_MODIFY_FINAL
544 /* Do any machine dependent final modifications */
545 IFCVT_MODIFY_FINAL (ce_info
);
548 /* Conversion succeeded. */
550 fprintf (rtl_dump_file
, "%d insn%s converted to conditional execution.\n",
551 n_insns
, (n_insns
== 1) ? " was" : "s were");
553 /* Merge the blocks! */
554 merge_if_block (ce_info
);
555 cond_exec_changed_p
= TRUE
;
559 #ifdef IFCVT_MODIFY_CANCEL
560 /* Cancel any machine dependent changes. */
561 IFCVT_MODIFY_CANCEL (ce_info
);
568 /* Used by noce_process_if_block to communicate with its subroutines.
570 The subroutines know that A and B may be evaluated freely. They
571 know that X is a register. They should insert new instructions
572 before cond_earliest. */
579 rtx jump
, cond
, cond_earliest
;
582 static rtx noce_emit_store_flag
PARAMS ((struct noce_if_info
*,
584 static int noce_try_store_flag
PARAMS ((struct noce_if_info
*));
585 static int noce_try_store_flag_inc
PARAMS ((struct noce_if_info
*));
586 static int noce_try_store_flag_constants
PARAMS ((struct noce_if_info
*));
587 static int noce_try_store_flag_mask
PARAMS ((struct noce_if_info
*));
588 static rtx noce_emit_cmove
PARAMS ((struct noce_if_info
*,
589 rtx
, enum rtx_code
, rtx
,
591 static int noce_try_cmove
PARAMS ((struct noce_if_info
*));
592 static int noce_try_cmove_arith
PARAMS ((struct noce_if_info
*));
593 static rtx noce_get_alt_condition
PARAMS ((struct noce_if_info
*,
595 static int noce_try_minmax
PARAMS ((struct noce_if_info
*));
596 static int noce_try_abs
PARAMS ((struct noce_if_info
*));
598 /* Helper function for noce_try_store_flag*. */
601 noce_emit_store_flag (if_info
, x
, reversep
, normalize
)
602 struct noce_if_info
*if_info
;
604 int reversep
, normalize
;
606 rtx cond
= if_info
->cond
;
610 cond_complex
= (! general_operand (XEXP (cond
, 0), VOIDmode
)
611 || ! general_operand (XEXP (cond
, 1), VOIDmode
));
613 /* If earliest == jump, or when the condition is complex, try to
614 build the store_flag insn directly. */
617 cond
= XEXP (SET_SRC (pc_set (if_info
->jump
)), 0);
620 code
= reversed_comparison_code (cond
, if_info
->jump
);
622 code
= GET_CODE (cond
);
624 if ((if_info
->cond_earliest
== if_info
->jump
|| cond_complex
)
625 && (normalize
== 0 || STORE_FLAG_VALUE
== normalize
))
629 tmp
= gen_rtx_fmt_ee (code
, GET_MODE (x
), XEXP (cond
, 0),
631 tmp
= gen_rtx_SET (VOIDmode
, x
, tmp
);
634 tmp
= emit_insn (tmp
);
636 if (recog_memoized (tmp
) >= 0)
642 if_info
->cond_earliest
= if_info
->jump
;
650 /* Don't even try if the comparison operands are weird. */
654 return emit_store_flag (x
, code
, XEXP (cond
, 0),
655 XEXP (cond
, 1), VOIDmode
,
656 (code
== LTU
|| code
== LEU
657 || code
== GEU
|| code
== GTU
), normalize
);
660 /* Emit instruction to move an rtx into STRICT_LOW_PART. */
662 noce_emit_move_insn (x
, y
)
665 enum machine_mode outmode
, inmode
;
669 if (GET_CODE (x
) != STRICT_LOW_PART
)
671 emit_move_insn (x
, y
);
676 inner
= XEXP (outer
, 0);
677 outmode
= GET_MODE (outer
);
678 inmode
= GET_MODE (inner
);
679 bitpos
= SUBREG_BYTE (outer
) * BITS_PER_UNIT
;
680 store_bit_field (inner
, GET_MODE_BITSIZE (outmode
), bitpos
, outmode
, y
,
681 GET_MODE_BITSIZE (inmode
));
684 /* Convert "if (test) x = 1; else x = 0".
686 Only try 0 and STORE_FLAG_VALUE here. Other combinations will be
687 tried in noce_try_store_flag_constants after noce_try_cmove has had
688 a go at the conversion. */
691 noce_try_store_flag (if_info
)
692 struct noce_if_info
*if_info
;
697 if (GET_CODE (if_info
->b
) == CONST_INT
698 && INTVAL (if_info
->b
) == STORE_FLAG_VALUE
699 && if_info
->a
== const0_rtx
)
701 else if (if_info
->b
== const0_rtx
702 && GET_CODE (if_info
->a
) == CONST_INT
703 && INTVAL (if_info
->a
) == STORE_FLAG_VALUE
704 && (reversed_comparison_code (if_info
->cond
, if_info
->jump
)
712 target
= noce_emit_store_flag (if_info
, if_info
->x
, reversep
, 0);
715 if (target
!= if_info
->x
)
716 noce_emit_move_insn (if_info
->x
, target
);
720 emit_insn_before_scope (seq
, if_info
->jump
, INSN_SCOPE (if_info
->insn_a
));
731 /* Convert "if (test) x = a; else x = b", for A and B constant. */
734 noce_try_store_flag_constants (if_info
)
735 struct noce_if_info
*if_info
;
739 HOST_WIDE_INT itrue
, ifalse
, diff
, tmp
;
740 int normalize
, can_reverse
;
741 enum machine_mode mode
;
744 && GET_CODE (if_info
->a
) == CONST_INT
745 && GET_CODE (if_info
->b
) == CONST_INT
)
747 mode
= GET_MODE (if_info
->x
);
748 ifalse
= INTVAL (if_info
->a
);
749 itrue
= INTVAL (if_info
->b
);
751 /* Make sure we can represent the difference between the two values. */
752 if ((itrue
- ifalse
> 0)
753 != ((ifalse
< 0) != (itrue
< 0) ? ifalse
< 0 : ifalse
< itrue
))
756 diff
= trunc_int_for_mode (itrue
- ifalse
, mode
);
758 can_reverse
= (reversed_comparison_code (if_info
->cond
, if_info
->jump
)
762 if (diff
== STORE_FLAG_VALUE
|| diff
== -STORE_FLAG_VALUE
)
764 else if (ifalse
== 0 && exact_log2 (itrue
) >= 0
765 && (STORE_FLAG_VALUE
== 1
766 || BRANCH_COST
>= 2))
768 else if (itrue
== 0 && exact_log2 (ifalse
) >= 0 && can_reverse
769 && (STORE_FLAG_VALUE
== 1 || BRANCH_COST
>= 2))
770 normalize
= 1, reversep
= 1;
772 && (STORE_FLAG_VALUE
== -1
773 || BRANCH_COST
>= 2))
775 else if (ifalse
== -1 && can_reverse
776 && (STORE_FLAG_VALUE
== -1 || BRANCH_COST
>= 2))
777 normalize
= -1, reversep
= 1;
778 else if ((BRANCH_COST
>= 2 && STORE_FLAG_VALUE
== -1)
786 tmp
= itrue
; itrue
= ifalse
; ifalse
= tmp
;
787 diff
= trunc_int_for_mode (-diff
, mode
);
791 target
= noce_emit_store_flag (if_info
, if_info
->x
, reversep
, normalize
);
798 /* if (test) x = 3; else x = 4;
799 => x = 3 + (test == 0); */
800 if (diff
== STORE_FLAG_VALUE
|| diff
== -STORE_FLAG_VALUE
)
802 target
= expand_simple_binop (mode
,
803 (diff
== STORE_FLAG_VALUE
805 GEN_INT (ifalse
), target
, if_info
->x
, 0,
809 /* if (test) x = 8; else x = 0;
810 => x = (test != 0) << 3; */
811 else if (ifalse
== 0 && (tmp
= exact_log2 (itrue
)) >= 0)
813 target
= expand_simple_binop (mode
, ASHIFT
,
814 target
, GEN_INT (tmp
), if_info
->x
, 0,
818 /* if (test) x = -1; else x = b;
819 => x = -(test != 0) | b; */
820 else if (itrue
== -1)
822 target
= expand_simple_binop (mode
, IOR
,
823 target
, GEN_INT (ifalse
), if_info
->x
, 0,
827 /* if (test) x = a; else x = b;
828 => x = (-(test != 0) & (b - a)) + a; */
831 target
= expand_simple_binop (mode
, AND
,
832 target
, GEN_INT (diff
), if_info
->x
, 0,
835 target
= expand_simple_binop (mode
, PLUS
,
836 target
, GEN_INT (ifalse
),
837 if_info
->x
, 0, OPTAB_WIDEN
);
846 if (target
!= if_info
->x
)
847 noce_emit_move_insn (if_info
->x
, target
);
852 if (seq_contains_jump (seq
))
855 emit_insn_before_scope (seq
, if_info
->jump
, INSN_SCOPE (if_info
->insn_a
));
863 /* Convert "if (test) foo++" into "foo += (test != 0)", and
864 similarly for "foo--". */
867 noce_try_store_flag_inc (if_info
)
868 struct noce_if_info
*if_info
;
871 int subtract
, normalize
;
877 /* Should be no `else' case to worry about. */
878 && if_info
->b
== if_info
->x
879 && GET_CODE (if_info
->a
) == PLUS
880 && (XEXP (if_info
->a
, 1) == const1_rtx
881 || XEXP (if_info
->a
, 1) == constm1_rtx
)
882 && rtx_equal_p (XEXP (if_info
->a
, 0), if_info
->x
)
883 && (reversed_comparison_code (if_info
->cond
, if_info
->jump
)
886 if (STORE_FLAG_VALUE
== INTVAL (XEXP (if_info
->a
, 1)))
887 subtract
= 0, normalize
= 0;
888 else if (-STORE_FLAG_VALUE
== INTVAL (XEXP (if_info
->a
, 1)))
889 subtract
= 1, normalize
= 0;
891 subtract
= 0, normalize
= INTVAL (XEXP (if_info
->a
, 1));
895 target
= noce_emit_store_flag (if_info
,
896 gen_reg_rtx (GET_MODE (if_info
->x
)),
900 target
= expand_simple_binop (GET_MODE (if_info
->x
),
901 subtract
? MINUS
: PLUS
,
902 if_info
->x
, target
, if_info
->x
,
906 if (target
!= if_info
->x
)
907 noce_emit_move_insn (if_info
->x
, target
);
912 if (seq_contains_jump (seq
))
915 emit_insn_before_scope (seq
, if_info
->jump
,
916 INSN_SCOPE (if_info
->insn_a
));
927 /* Convert "if (test) x = 0;" to "x &= -(test == 0);" */
930 noce_try_store_flag_mask (if_info
)
931 struct noce_if_info
*if_info
;
939 || STORE_FLAG_VALUE
== -1)
940 && ((if_info
->a
== const0_rtx
941 && rtx_equal_p (if_info
->b
, if_info
->x
))
942 || ((reversep
= (reversed_comparison_code (if_info
->cond
,
945 && if_info
->b
== const0_rtx
946 && rtx_equal_p (if_info
->a
, if_info
->x
))))
949 target
= noce_emit_store_flag (if_info
,
950 gen_reg_rtx (GET_MODE (if_info
->x
)),
953 target
= expand_simple_binop (GET_MODE (if_info
->x
), AND
,
954 if_info
->x
, target
, if_info
->x
, 0,
959 if (target
!= if_info
->x
)
960 noce_emit_move_insn (if_info
->x
, target
);
965 if (seq_contains_jump (seq
))
968 emit_insn_before_scope (seq
, if_info
->jump
,
969 INSN_SCOPE (if_info
->insn_a
));
980 /* Helper function for noce_try_cmove and noce_try_cmove_arith. */
983 noce_emit_cmove (if_info
, x
, code
, cmp_a
, cmp_b
, vfalse
, vtrue
)
984 struct noce_if_info
*if_info
;
985 rtx x
, cmp_a
, cmp_b
, vfalse
, vtrue
;
988 /* If earliest == jump, try to build the cmove insn directly.
989 This is helpful when combine has created some complex condition
990 (like for alpha's cmovlbs) that we can't hope to regenerate
991 through the normal interface. */
993 if (if_info
->cond_earliest
== if_info
->jump
)
997 tmp
= gen_rtx_fmt_ee (code
, GET_MODE (if_info
->cond
), cmp_a
, cmp_b
);
998 tmp
= gen_rtx_IF_THEN_ELSE (GET_MODE (x
), tmp
, vtrue
, vfalse
);
999 tmp
= gen_rtx_SET (VOIDmode
, x
, tmp
);
1002 tmp
= emit_insn (tmp
);
1004 if (recog_memoized (tmp
) >= 0)
1016 /* Don't even try if the comparison operands are weird. */
1017 if (! general_operand (cmp_a
, GET_MODE (cmp_a
))
1018 || ! general_operand (cmp_b
, GET_MODE (cmp_b
)))
1021 #if HAVE_conditional_move
1022 return emit_conditional_move (x
, code
, cmp_a
, cmp_b
, VOIDmode
,
1023 vtrue
, vfalse
, GET_MODE (x
),
1024 (code
== LTU
|| code
== GEU
1025 || code
== LEU
|| code
== GTU
));
1027 /* We'll never get here, as noce_process_if_block doesn't call the
1028 functions involved. Ifdef code, however, should be discouraged
1029 because it leads to typos in the code not selected. However,
1030 emit_conditional_move won't exist either. */
1035 /* Try only simple constants and registers here. More complex cases
1036 are handled in noce_try_cmove_arith after noce_try_store_flag_arith
1037 has had a go at it. */
1040 noce_try_cmove (if_info
)
1041 struct noce_if_info
*if_info
;
1046 if ((CONSTANT_P (if_info
->a
) || register_operand (if_info
->a
, VOIDmode
))
1047 && (CONSTANT_P (if_info
->b
) || register_operand (if_info
->b
, VOIDmode
)))
1051 code
= GET_CODE (if_info
->cond
);
1052 target
= noce_emit_cmove (if_info
, if_info
->x
, code
,
1053 XEXP (if_info
->cond
, 0),
1054 XEXP (if_info
->cond
, 1),
1055 if_info
->a
, if_info
->b
);
1059 if (target
!= if_info
->x
)
1060 noce_emit_move_insn (if_info
->x
, target
);
1064 emit_insn_before_scope (seq
, if_info
->jump
,
1065 INSN_SCOPE (if_info
->insn_a
));
1078 /* Try more complex cases involving conditional_move. */
1081 noce_try_cmove_arith (if_info
)
1082 struct noce_if_info
*if_info
;
1092 /* A conditional move from two memory sources is equivalent to a
1093 conditional on their addresses followed by a load. Don't do this
1094 early because it'll screw alias analysis. Note that we've
1095 already checked for no side effects. */
1096 if (! no_new_pseudos
&& cse_not_expected
1097 && GET_CODE (a
) == MEM
&& GET_CODE (b
) == MEM
1098 && BRANCH_COST
>= 5)
1102 x
= gen_reg_rtx (Pmode
);
1106 /* ??? We could handle this if we knew that a load from A or B could
1107 not fault. This is also true if we've already loaded
1108 from the address along the path from ENTRY. */
1109 else if (may_trap_p (a
) || may_trap_p (b
))
1112 /* if (test) x = a + b; else x = c - d;
1119 code
= GET_CODE (if_info
->cond
);
1120 insn_a
= if_info
->insn_a
;
1121 insn_b
= if_info
->insn_b
;
1123 /* Possibly rearrange operands to make things come out more natural. */
1124 if (reversed_comparison_code (if_info
->cond
, if_info
->jump
) != UNKNOWN
)
1127 if (rtx_equal_p (b
, x
))
1129 else if (general_operand (b
, GET_MODE (b
)))
1134 code
= reversed_comparison_code (if_info
->cond
, if_info
->jump
);
1135 tmp
= a
, a
= b
, b
= tmp
;
1136 tmp
= insn_a
, insn_a
= insn_b
, insn_b
= tmp
;
1142 /* If either operand is complex, load it into a register first.
1143 The best way to do this is to copy the original insn. In this
1144 way we preserve any clobbers etc that the insn may have had.
1145 This is of course not possible in the IS_MEM case. */
1146 if (! general_operand (a
, GET_MODE (a
)))
1151 goto end_seq_and_fail
;
1155 tmp
= gen_reg_rtx (GET_MODE (a
));
1156 tmp
= emit_insn (gen_rtx_SET (VOIDmode
, tmp
, a
));
1159 goto end_seq_and_fail
;
1162 a
= gen_reg_rtx (GET_MODE (a
));
1163 tmp
= copy_rtx (insn_a
);
1164 set
= single_set (tmp
);
1166 tmp
= emit_insn (PATTERN (tmp
));
1168 if (recog_memoized (tmp
) < 0)
1169 goto end_seq_and_fail
;
1171 if (! general_operand (b
, GET_MODE (b
)))
1176 goto end_seq_and_fail
;
1180 tmp
= gen_reg_rtx (GET_MODE (b
));
1181 tmp
= emit_insn (gen_rtx_SET (VOIDmode
, tmp
, b
));
1184 goto end_seq_and_fail
;
1187 b
= gen_reg_rtx (GET_MODE (b
));
1188 tmp
= copy_rtx (insn_b
);
1189 set
= single_set (tmp
);
1191 tmp
= emit_insn (PATTERN (tmp
));
1193 if (recog_memoized (tmp
) < 0)
1194 goto end_seq_and_fail
;
1197 target
= noce_emit_cmove (if_info
, x
, code
, XEXP (if_info
->cond
, 0),
1198 XEXP (if_info
->cond
, 1), a
, b
);
1201 goto end_seq_and_fail
;
1203 /* If we're handling a memory for above, emit the load now. */
1206 tmp
= gen_rtx_MEM (GET_MODE (if_info
->x
), target
);
1208 /* Copy over flags as appropriate. */
1209 if (MEM_VOLATILE_P (if_info
->a
) || MEM_VOLATILE_P (if_info
->b
))
1210 MEM_VOLATILE_P (tmp
) = 1;
1211 if (MEM_IN_STRUCT_P (if_info
->a
) && MEM_IN_STRUCT_P (if_info
->b
))
1212 MEM_IN_STRUCT_P (tmp
) = 1;
1213 if (MEM_SCALAR_P (if_info
->a
) && MEM_SCALAR_P (if_info
->b
))
1214 MEM_SCALAR_P (tmp
) = 1;
1215 if (MEM_ALIAS_SET (if_info
->a
) == MEM_ALIAS_SET (if_info
->b
))
1216 set_mem_alias_set (tmp
, MEM_ALIAS_SET (if_info
->a
));
1218 MIN (MEM_ALIGN (if_info
->a
), MEM_ALIGN (if_info
->b
)));
1220 noce_emit_move_insn (if_info
->x
, tmp
);
1222 else if (target
!= x
)
1223 noce_emit_move_insn (x
, target
);
1227 emit_insn_before_scope (tmp
, if_info
->jump
, INSN_SCOPE (if_info
->insn_a
));
1235 /* For most cases, the simplified condition we found is the best
1236 choice, but this is not the case for the min/max/abs transforms.
1237 For these we wish to know that it is A or B in the condition. */
1240 noce_get_alt_condition (if_info
, target
, earliest
)
1241 struct noce_if_info
*if_info
;
1245 rtx cond
, set
, insn
;
1248 /* If target is already mentioned in the known condition, return it. */
1249 if (reg_mentioned_p (target
, if_info
->cond
))
1251 *earliest
= if_info
->cond_earliest
;
1252 return if_info
->cond
;
1255 set
= pc_set (if_info
->jump
);
1256 cond
= XEXP (SET_SRC (set
), 0);
1258 = GET_CODE (XEXP (SET_SRC (set
), 2)) == LABEL_REF
1259 && XEXP (XEXP (SET_SRC (set
), 2), 0) == JUMP_LABEL (if_info
->jump
);
1261 /* If we're looking for a constant, try to make the conditional
1262 have that constant in it. There are two reasons why it may
1263 not have the constant we want:
1265 1. GCC may have needed to put the constant in a register, because
1266 the target can't compare directly against that constant. For
1267 this case, we look for a SET immediately before the comparison
1268 that puts a constant in that register.
1270 2. GCC may have canonicalized the conditional, for example
1271 replacing "if x < 4" with "if x <= 3". We can undo that (or
1272 make equivalent types of changes) to get the constants we need
1273 if they're off by one in the right direction. */
1275 if (GET_CODE (target
) == CONST_INT
)
1277 enum rtx_code code
= GET_CODE (if_info
->cond
);
1278 rtx op_a
= XEXP (if_info
->cond
, 0);
1279 rtx op_b
= XEXP (if_info
->cond
, 1);
1282 /* First, look to see if we put a constant in a register. */
1283 prev_insn
= PREV_INSN (if_info
->cond_earliest
);
1285 && INSN_P (prev_insn
)
1286 && GET_CODE (PATTERN (prev_insn
)) == SET
)
1288 rtx src
= find_reg_equal_equiv_note (prev_insn
);
1290 src
= SET_SRC (PATTERN (prev_insn
));
1291 if (GET_CODE (src
) == CONST_INT
)
1293 if (rtx_equal_p (op_a
, SET_DEST (PATTERN (prev_insn
))))
1295 else if (rtx_equal_p (op_b
, SET_DEST (PATTERN (prev_insn
))))
1298 if (GET_CODE (op_a
) == CONST_INT
)
1303 code
= swap_condition (code
);
1308 /* Now, look to see if we can get the right constant by
1309 adjusting the conditional. */
1310 if (GET_CODE (op_b
) == CONST_INT
)
1312 HOST_WIDE_INT desired_val
= INTVAL (target
);
1313 HOST_WIDE_INT actual_val
= INTVAL (op_b
);
1318 if (actual_val
== desired_val
+ 1)
1321 op_b
= GEN_INT (desired_val
);
1325 if (actual_val
== desired_val
- 1)
1328 op_b
= GEN_INT (desired_val
);
1332 if (actual_val
== desired_val
- 1)
1335 op_b
= GEN_INT (desired_val
);
1339 if (actual_val
== desired_val
+ 1)
1342 op_b
= GEN_INT (desired_val
);
1350 /* If we made any changes, generate a new conditional that is
1351 equivalent to what we started with, but has the right
1353 if (code
!= GET_CODE (if_info
->cond
)
1354 || op_a
!= XEXP (if_info
->cond
, 0)
1355 || op_b
!= XEXP (if_info
->cond
, 1))
1357 cond
= gen_rtx_fmt_ee (code
, GET_MODE (cond
), op_a
, op_b
);
1358 *earliest
= if_info
->cond_earliest
;
1363 cond
= canonicalize_condition (if_info
->jump
, cond
, reverse
,
1365 if (! cond
|| ! reg_mentioned_p (target
, cond
))
1368 /* We almost certainly searched back to a different place.
1369 Need to re-verify correct lifetimes. */
1371 /* X may not be mentioned in the range (cond_earliest, jump]. */
1372 for (insn
= if_info
->jump
; insn
!= *earliest
; insn
= PREV_INSN (insn
))
1373 if (INSN_P (insn
) && reg_overlap_mentioned_p (if_info
->x
, PATTERN (insn
)))
1376 /* A and B may not be modified in the range [cond_earliest, jump). */
1377 for (insn
= *earliest
; insn
!= if_info
->jump
; insn
= NEXT_INSN (insn
))
1379 && (modified_in_p (if_info
->a
, insn
)
1380 || modified_in_p (if_info
->b
, insn
)))
1386 /* Convert "if (a < b) x = a; else x = b;" to "x = min(a, b);", etc. */
1389 noce_try_minmax (if_info
)
1390 struct noce_if_info
*if_info
;
1392 rtx cond
, earliest
, target
, seq
;
1393 enum rtx_code code
, op
;
1396 /* ??? Can't guarantee that expand_binop won't create pseudos. */
1400 /* ??? Reject modes with NaNs or signed zeros since we don't know how
1401 they will be resolved with an SMIN/SMAX. It wouldn't be too hard
1402 to get the target to tell us... */
1403 if (HONOR_SIGNED_ZEROS (GET_MODE (if_info
->x
))
1404 || HONOR_NANS (GET_MODE (if_info
->x
)))
1407 cond
= noce_get_alt_condition (if_info
, if_info
->a
, &earliest
);
1411 /* Verify the condition is of the form we expect, and canonicalize
1412 the comparison code. */
1413 code
= GET_CODE (cond
);
1414 if (rtx_equal_p (XEXP (cond
, 0), if_info
->a
))
1416 if (! rtx_equal_p (XEXP (cond
, 1), if_info
->b
))
1419 else if (rtx_equal_p (XEXP (cond
, 1), if_info
->a
))
1421 if (! rtx_equal_p (XEXP (cond
, 0), if_info
->b
))
1423 code
= swap_condition (code
);
1428 /* Determine what sort of operation this is. Note that the code is for
1429 a taken branch, so the code->operation mapping appears backwards. */
1462 target
= expand_simple_binop (GET_MODE (if_info
->x
), op
,
1463 if_info
->a
, if_info
->b
,
1464 if_info
->x
, unsignedp
, OPTAB_WIDEN
);
1470 if (target
!= if_info
->x
)
1471 noce_emit_move_insn (if_info
->x
, target
);
1476 if (seq_contains_jump (seq
))
1479 emit_insn_before_scope (seq
, if_info
->jump
, INSN_SCOPE (if_info
->insn_a
));
1480 if_info
->cond
= cond
;
1481 if_info
->cond_earliest
= earliest
;
1486 /* Convert "if (a < 0) x = -a; else x = a;" to "x = abs(a);", etc. */
1489 noce_try_abs (if_info
)
1490 struct noce_if_info
*if_info
;
1492 rtx cond
, earliest
, target
, seq
, a
, b
, c
;
1495 /* ??? Can't guarantee that expand_binop won't create pseudos. */
1499 /* Recognize A and B as constituting an ABS or NABS. */
1502 if (GET_CODE (a
) == NEG
&& rtx_equal_p (XEXP (a
, 0), b
))
1504 else if (GET_CODE (b
) == NEG
&& rtx_equal_p (XEXP (b
, 0), a
))
1506 c
= a
; a
= b
; b
= c
;
1512 cond
= noce_get_alt_condition (if_info
, b
, &earliest
);
1516 /* Verify the condition is of the form we expect. */
1517 if (rtx_equal_p (XEXP (cond
, 0), b
))
1519 else if (rtx_equal_p (XEXP (cond
, 1), b
))
1524 /* Verify that C is zero. Search backward through the block for
1525 a REG_EQUAL note if necessary. */
1528 rtx insn
, note
= NULL
;
1529 for (insn
= earliest
;
1530 insn
!= if_info
->test_bb
->head
;
1531 insn
= PREV_INSN (insn
))
1533 && ((note
= find_reg_note (insn
, REG_EQUAL
, c
))
1534 || (note
= find_reg_note (insn
, REG_EQUIV
, c
))))
1540 if (GET_CODE (c
) == MEM
1541 && GET_CODE (XEXP (c
, 0)) == SYMBOL_REF
1542 && CONSTANT_POOL_ADDRESS_P (XEXP (c
, 0)))
1543 c
= get_pool_constant (XEXP (c
, 0));
1545 /* Work around funny ideas get_condition has wrt canonicalization.
1546 Note that these rtx constants are known to be CONST_INT, and
1547 therefore imply integer comparisons. */
1548 if (c
== constm1_rtx
&& GET_CODE (cond
) == GT
)
1550 else if (c
== const1_rtx
&& GET_CODE (cond
) == LT
)
1552 else if (c
!= CONST0_RTX (GET_MODE (b
)))
1555 /* Determine what sort of operation this is. */
1556 switch (GET_CODE (cond
))
1575 target
= expand_simple_unop (GET_MODE (if_info
->x
), ABS
, b
, if_info
->x
, 0);
1577 /* ??? It's a quandry whether cmove would be better here, especially
1578 for integers. Perhaps combine will clean things up. */
1579 if (target
&& negate
)
1580 target
= expand_simple_unop (GET_MODE (target
), NEG
, target
, if_info
->x
, 0);
1588 if (target
!= if_info
->x
)
1589 noce_emit_move_insn (if_info
->x
, target
);
1594 if (seq_contains_jump (seq
))
1597 emit_insn_before_scope (seq
, if_info
->jump
, INSN_SCOPE (if_info
->insn_a
));
1598 if_info
->cond
= cond
;
1599 if_info
->cond_earliest
= earliest
;
1604 /* Similar to get_condition, only the resulting condition must be
1605 valid at JUMP, instead of at EARLIEST. */
1608 noce_get_condition (jump
, earliest
)
1612 rtx cond
, set
, tmp
, insn
;
1615 if (! any_condjump_p (jump
))
1618 set
= pc_set (jump
);
1620 /* If this branches to JUMP_LABEL when the condition is false,
1621 reverse the condition. */
1622 reverse
= (GET_CODE (XEXP (SET_SRC (set
), 2)) == LABEL_REF
1623 && XEXP (XEXP (SET_SRC (set
), 2), 0) == JUMP_LABEL (jump
));
1625 /* If the condition variable is a register and is MODE_INT, accept it. */
1627 cond
= XEXP (SET_SRC (set
), 0);
1628 tmp
= XEXP (cond
, 0);
1629 if (REG_P (tmp
) && GET_MODE_CLASS (GET_MODE (tmp
)) == MODE_INT
)
1634 cond
= gen_rtx_fmt_ee (reverse_condition (GET_CODE (cond
)),
1635 GET_MODE (cond
), tmp
, XEXP (cond
, 1));
1639 /* Otherwise, fall back on canonicalize_condition to do the dirty
1640 work of manipulating MODE_CC values and COMPARE rtx codes. */
1642 tmp
= canonicalize_condition (jump
, cond
, reverse
, earliest
, NULL_RTX
);
1646 /* We are going to insert code before JUMP, not before EARLIEST.
1647 We must therefore be certain that the given condition is valid
1648 at JUMP by virtue of not having been modified since. */
1649 for (insn
= *earliest
; insn
!= jump
; insn
= NEXT_INSN (insn
))
1650 if (INSN_P (insn
) && modified_in_p (tmp
, insn
))
1655 /* The condition was modified. See if we can get a partial result
1656 that doesn't follow all the reversals. Perhaps combine can fold
1657 them together later. */
1658 tmp
= XEXP (tmp
, 0);
1659 if (!REG_P (tmp
) || GET_MODE_CLASS (GET_MODE (tmp
)) != MODE_INT
)
1661 tmp
= canonicalize_condition (jump
, cond
, reverse
, earliest
, tmp
);
1665 /* For sanity's sake, re-validate the new result. */
1666 for (insn
= *earliest
; insn
!= jump
; insn
= NEXT_INSN (insn
))
1667 if (INSN_P (insn
) && modified_in_p (tmp
, insn
))
1673 /* Return true if OP is ok for if-then-else processing. */
1676 noce_operand_ok (op
)
1679 /* We special-case memories, so handle any of them with
1680 no address side effects. */
1681 if (GET_CODE (op
) == MEM
)
1682 return ! side_effects_p (XEXP (op
, 0));
1684 if (side_effects_p (op
))
1687 return ! may_trap_p (op
);
1690 /* Given a simple IF-THEN or IF-THEN-ELSE block, attempt to convert it
1691 without using conditional execution. Return TRUE if we were
1692 successful at converting the block. */
1695 noce_process_if_block (ce_info
)
1696 struct ce_if_block
* ce_info
;
1698 basic_block test_bb
= ce_info
->test_bb
; /* test block */
1699 basic_block then_bb
= ce_info
->then_bb
; /* THEN */
1700 basic_block else_bb
= ce_info
->else_bb
; /* ELSE or NULL */
1701 struct noce_if_info if_info
;
1704 rtx orig_x
, x
, a
, b
;
1707 /* We're looking for patterns of the form
1709 (1) if (...) x = a; else x = b;
1710 (2) x = b; if (...) x = a;
1711 (3) if (...) x = a; // as if with an initial x = x.
1713 The later patterns require jumps to be more expensive.
1715 ??? For future expansion, look for multiple X in such patterns. */
1717 /* If test is comprised of && or || elements, don't handle it unless it is
1718 the special case of && elements without an ELSE block. */
1719 if (ce_info
->num_multiple_test_blocks
)
1721 if (else_bb
|| ! ce_info
->and_and_p
)
1724 ce_info
->test_bb
= test_bb
= ce_info
->last_test_bb
;
1725 ce_info
->num_multiple_test_blocks
= 0;
1726 ce_info
->num_and_and_blocks
= 0;
1727 ce_info
->num_or_or_blocks
= 0;
1730 /* If this is not a standard conditional jump, we can't parse it. */
1731 jump
= test_bb
->end
;
1732 cond
= noce_get_condition (jump
, &if_info
.cond_earliest
);
1736 /* If the conditional jump is more than just a conditional
1737 jump, then we can not do if-conversion on this block. */
1738 if (! onlyjump_p (jump
))
1741 /* We must be comparing objects whose modes imply the size. */
1742 if (GET_MODE (XEXP (cond
, 0)) == BLKmode
)
1745 /* Look for one of the potential sets. */
1746 insn_a
= first_active_insn (then_bb
);
1748 || insn_a
!= last_active_insn (then_bb
, FALSE
)
1749 || (set_a
= single_set (insn_a
)) == NULL_RTX
)
1752 x
= SET_DEST (set_a
);
1753 a
= SET_SRC (set_a
);
1755 /* Look for the other potential set. Make sure we've got equivalent
1757 /* ??? This is overconservative. Storing to two different mems is
1758 as easy as conditionally computing the address. Storing to a
1759 single mem merely requires a scratch memory to use as one of the
1760 destination addresses; often the memory immediately below the
1761 stack pointer is available for this. */
1765 insn_b
= first_active_insn (else_bb
);
1767 || insn_b
!= last_active_insn (else_bb
, FALSE
)
1768 || (set_b
= single_set (insn_b
)) == NULL_RTX
1769 || ! rtx_equal_p (x
, SET_DEST (set_b
)))
1774 insn_b
= prev_nonnote_insn (if_info
.cond_earliest
);
1776 || GET_CODE (insn_b
) != INSN
1777 || (set_b
= single_set (insn_b
)) == NULL_RTX
1778 || ! rtx_equal_p (x
, SET_DEST (set_b
))
1779 || reg_overlap_mentioned_p (x
, cond
)
1780 || reg_overlap_mentioned_p (x
, a
)
1781 || reg_overlap_mentioned_p (x
, SET_SRC (set_b
))
1782 || modified_between_p (x
, if_info
.cond_earliest
, NEXT_INSN (jump
)))
1783 insn_b
= set_b
= NULL_RTX
;
1785 b
= (set_b
? SET_SRC (set_b
) : x
);
1787 /* Only operate on register destinations, and even then avoid extending
1788 the lifetime of hard registers on small register class machines. */
1790 if (GET_CODE (x
) != REG
1791 || (SMALL_REGISTER_CLASSES
1792 && REGNO (x
) < FIRST_PSEUDO_REGISTER
))
1796 x
= gen_reg_rtx (GET_MODE (GET_CODE (x
) == STRICT_LOW_PART
1797 ? XEXP (x
, 0) : x
));
1800 /* Don't operate on sources that may trap or are volatile. */
1801 if (! noce_operand_ok (a
) || ! noce_operand_ok (b
))
1804 /* Set up the info block for our subroutines. */
1805 if_info
.test_bb
= test_bb
;
1806 if_info
.cond
= cond
;
1807 if_info
.jump
= jump
;
1808 if_info
.insn_a
= insn_a
;
1809 if_info
.insn_b
= insn_b
;
1814 /* Try optimizations in some approximation of a useful order. */
1815 /* ??? Should first look to see if X is live incoming at all. If it
1816 isn't, we don't need anything but an unconditional set. */
1818 /* Look and see if A and B are really the same. Avoid creating silly
1819 cmove constructs that no one will fix up later. */
1820 if (rtx_equal_p (a
, b
))
1822 /* If we have an INSN_B, we don't have to create any new rtl. Just
1823 move the instruction that we already have. If we don't have an
1824 INSN_B, that means that A == X, and we've got a noop move. In
1825 that case don't do anything and let the code below delete INSN_A. */
1826 if (insn_b
&& else_bb
)
1830 if (else_bb
&& insn_b
== else_bb
->end
)
1831 else_bb
->end
= PREV_INSN (insn_b
);
1832 reorder_insns (insn_b
, insn_b
, PREV_INSN (jump
));
1834 /* If there was a REG_EQUAL note, delete it since it may have been
1835 true due to this insn being after a jump. */
1836 if ((note
= find_reg_note (insn_b
, REG_EQUAL
, NULL_RTX
)) != 0)
1837 remove_note (insn_b
, note
);
1841 /* If we have "x = b; if (...) x = a;", and x has side-effects, then
1842 x must be executed twice. */
1843 else if (insn_b
&& side_effects_p (orig_x
))
1850 if (noce_try_store_flag (&if_info
))
1852 if (noce_try_minmax (&if_info
))
1854 if (noce_try_abs (&if_info
))
1856 if (HAVE_conditional_move
1857 && noce_try_cmove (&if_info
))
1859 if (! HAVE_conditional_execution
)
1861 if (noce_try_store_flag_constants (&if_info
))
1863 if (noce_try_store_flag_inc (&if_info
))
1865 if (noce_try_store_flag_mask (&if_info
))
1867 if (HAVE_conditional_move
1868 && noce_try_cmove_arith (&if_info
))
1875 /* The original sets may now be killed. */
1876 delete_insn (insn_a
);
1878 /* Several special cases here: First, we may have reused insn_b above,
1879 in which case insn_b is now NULL. Second, we want to delete insn_b
1880 if it came from the ELSE block, because follows the now correct
1881 write that appears in the TEST block. However, if we got insn_b from
1882 the TEST block, it may in fact be loading data needed for the comparison.
1883 We'll let life_analysis remove the insn if it's really dead. */
1884 if (insn_b
&& else_bb
)
1885 delete_insn (insn_b
);
1887 /* The new insns will have been inserted immediately before the jump. We
1888 should be able to remove the jump with impunity, but the condition itself
1889 may have been modified by gcse to be shared across basic blocks. */
1892 /* If we used a temporary, fix it up now. */
1896 noce_emit_move_insn (copy_rtx (orig_x
), x
);
1897 insn_b
= get_insns ();
1900 emit_insn_after_scope (insn_b
, test_bb
->end
, INSN_SCOPE (insn_a
));
1903 /* Merge the blocks! */
1904 merge_if_block (ce_info
);
1909 /* Attempt to convert an IF-THEN or IF-THEN-ELSE block into
1910 straight line code. Return true if successful. */
1913 process_if_block (ce_info
)
1914 struct ce_if_block
* ce_info
;
1916 if (! reload_completed
1917 && noce_process_if_block (ce_info
))
1920 if (HAVE_conditional_execution
&& reload_completed
)
1922 /* If we have && and || tests, try to first handle combining the && and
1923 || tests into the conditional code, and if that fails, go back and
1924 handle it without the && and ||, which at present handles the && case
1925 if there was no ELSE block. */
1926 if (cond_exec_process_if_block (ce_info
, TRUE
))
1929 if (ce_info
->num_multiple_test_blocks
)
1933 if (cond_exec_process_if_block (ce_info
, FALSE
))
1941 /* Merge the blocks and mark for local life update. */
1944 merge_if_block (ce_info
)
1945 struct ce_if_block
* ce_info
;
1947 basic_block test_bb
= ce_info
->test_bb
; /* last test block */
1948 basic_block then_bb
= ce_info
->then_bb
; /* THEN */
1949 basic_block else_bb
= ce_info
->else_bb
; /* ELSE or NULL */
1950 basic_block join_bb
= ce_info
->join_bb
; /* join block */
1951 basic_block combo_bb
;
1953 /* All block merging is done into the lower block numbers. */
1957 /* Merge any basic blocks to handle && and || subtests. Each of
1958 the blocks are on the fallthru path from the predecessor block. */
1959 if (ce_info
->num_multiple_test_blocks
> 0)
1961 basic_block bb
= test_bb
;
1962 basic_block last_test_bb
= ce_info
->last_test_bb
;
1963 basic_block fallthru
= block_fallthru (bb
);
1968 fallthru
= block_fallthru (bb
);
1969 if (post_dominators
)
1970 delete_from_dominance_info (post_dominators
, bb
);
1971 merge_blocks_nomove (combo_bb
, bb
);
1972 num_removed_blocks
++;
1974 while (bb
!= last_test_bb
);
1977 /* Merge TEST block into THEN block. Normally the THEN block won't have a
1978 label, but it might if there were || tests. That label's count should be
1979 zero, and it normally should be removed. */
1983 if (combo_bb
->global_live_at_end
)
1984 COPY_REG_SET (combo_bb
->global_live_at_end
,
1985 then_bb
->global_live_at_end
);
1986 if (post_dominators
)
1987 delete_from_dominance_info (post_dominators
, then_bb
);
1988 merge_blocks_nomove (combo_bb
, then_bb
);
1989 num_removed_blocks
++;
1992 /* The ELSE block, if it existed, had a label. That label count
1993 will almost always be zero, but odd things can happen when labels
1994 get their addresses taken. */
1997 if (post_dominators
)
1998 delete_from_dominance_info (post_dominators
, else_bb
);
1999 merge_blocks_nomove (combo_bb
, else_bb
);
2000 num_removed_blocks
++;
2003 /* If there was no join block reported, that means it was not adjacent
2004 to the others, and so we cannot merge them. */
2008 rtx last
= combo_bb
->end
;
2010 /* The outgoing edge for the current COMBO block should already
2011 be correct. Verify this. */
2012 if (combo_bb
->succ
== NULL_EDGE
)
2014 if (find_reg_note (last
, REG_NORETURN
, NULL
))
2016 else if (GET_CODE (last
) == INSN
2017 && GET_CODE (PATTERN (last
)) == TRAP_IF
2018 && TRAP_CONDITION (PATTERN (last
)) == const_true_rtx
)
2024 /* There should still be something at the end of the THEN or ELSE
2025 blocks taking us to our final destination. */
2026 else if (GET_CODE (last
) == JUMP_INSN
)
2028 else if (combo_bb
->succ
->dest
== EXIT_BLOCK_PTR
2029 && GET_CODE (last
) == CALL_INSN
2030 && SIBLING_CALL_P (last
))
2032 else if ((combo_bb
->succ
->flags
& EDGE_EH
)
2033 && can_throw_internal (last
))
2039 /* The JOIN block may have had quite a number of other predecessors too.
2040 Since we've already merged the TEST, THEN and ELSE blocks, we should
2041 have only one remaining edge from our if-then-else diamond. If there
2042 is more than one remaining edge, it must come from elsewhere. There
2043 may be zero incoming edges if the THEN block didn't actually join
2044 back up (as with a call to abort). */
2045 else if ((join_bb
->pred
== NULL
2046 || join_bb
->pred
->pred_next
== NULL
)
2047 && join_bb
!= EXIT_BLOCK_PTR
)
2049 /* We can merge the JOIN. */
2050 if (combo_bb
->global_live_at_end
)
2051 COPY_REG_SET (combo_bb
->global_live_at_end
,
2052 join_bb
->global_live_at_end
);
2054 if (post_dominators
)
2055 delete_from_dominance_info (post_dominators
, join_bb
);
2056 merge_blocks_nomove (combo_bb
, join_bb
);
2057 num_removed_blocks
++;
2061 /* We cannot merge the JOIN. */
2063 /* The outgoing edge for the current COMBO block should already
2064 be correct. Verify this. */
2065 if (combo_bb
->succ
->succ_next
!= NULL_EDGE
2066 || combo_bb
->succ
->dest
!= join_bb
)
2069 /* Remove the jump and cruft from the end of the COMBO block. */
2070 if (join_bb
!= EXIT_BLOCK_PTR
)
2071 tidy_fallthru_edge (combo_bb
->succ
, combo_bb
, join_bb
);
2074 num_updated_if_blocks
++;
2077 /* Find a block ending in a simple IF condition and try to transform it
2078 in some way. When converting a multi-block condition, put the new code
2079 in the first such block and delete the rest. Return a pointer to this
2080 first block if some transformation was done. Return NULL otherwise. */
2083 find_if_header (test_bb
, pass
)
2084 basic_block test_bb
;
2087 ce_if_block_t ce_info
;
2091 /* The kind of block we're looking for has exactly two successors. */
2092 if ((then_edge
= test_bb
->succ
) == NULL_EDGE
2093 || (else_edge
= then_edge
->succ_next
) == NULL_EDGE
2094 || else_edge
->succ_next
!= NULL_EDGE
)
2097 /* Neither edge should be abnormal. */
2098 if ((then_edge
->flags
& EDGE_COMPLEX
)
2099 || (else_edge
->flags
& EDGE_COMPLEX
))
2102 /* The THEN edge is canonically the one that falls through. */
2103 if (then_edge
->flags
& EDGE_FALLTHRU
)
2105 else if (else_edge
->flags
& EDGE_FALLTHRU
)
2108 else_edge
= then_edge
;
2112 /* Otherwise this must be a multiway branch of some sort. */
2115 memset ((PTR
) &ce_info
, '\0', sizeof (ce_info
));
2116 ce_info
.test_bb
= test_bb
;
2117 ce_info
.then_bb
= then_edge
->dest
;
2118 ce_info
.else_bb
= else_edge
->dest
;
2119 ce_info
.pass
= pass
;
2121 #ifdef IFCVT_INIT_EXTRA_FIELDS
2122 IFCVT_INIT_EXTRA_FIELDS (&ce_info
);
2125 if (find_if_block (&ce_info
))
2128 if (HAVE_trap
&& HAVE_conditional_trap
2129 && find_cond_trap (test_bb
, then_edge
, else_edge
))
2133 && (! HAVE_conditional_execution
|| reload_completed
))
2135 if (find_if_case_1 (test_bb
, then_edge
, else_edge
))
2137 if (find_if_case_2 (test_bb
, then_edge
, else_edge
))
2145 fprintf (rtl_dump_file
, "Conversion succeeded on pass %d.\n", pass
);
2146 return ce_info
.test_bb
;
2149 /* Return true if a block has two edges, one of which falls through to the next
2150 block, and the other jumps to a specific block, so that we can tell if the
2151 block is part of an && test or an || test. Returns either -1 or the number
2152 of non-note, non-jump, non-USE/CLOBBER insns in the block. */
2155 block_jumps_and_fallthru_p (cur_bb
, target_bb
)
2157 basic_block target_bb
;
2160 int fallthru_p
= FALSE
;
2166 if (!cur_bb
|| !target_bb
)
2169 /* If no edges, obviously it doesn't jump or fallthru. */
2170 if (cur_bb
->succ
== NULL_EDGE
)
2173 for (cur_edge
= cur_bb
->succ
;
2174 cur_edge
!= NULL_EDGE
;
2175 cur_edge
= cur_edge
->succ_next
)
2177 if (cur_edge
->flags
& EDGE_COMPLEX
)
2178 /* Anything complex isn't what we want. */
2181 else if (cur_edge
->flags
& EDGE_FALLTHRU
)
2184 else if (cur_edge
->dest
== target_bb
)
2191 if ((jump_p
& fallthru_p
) == 0)
2194 /* Don't allow calls in the block, since this is used to group && and ||
2195 together for conditional execution support. ??? we should support
2196 conditional execution support across calls for IA-64 some day, but
2197 for now it makes the code simpler. */
2199 insn
= cur_bb
->head
;
2201 while (insn
!= NULL_RTX
)
2203 if (GET_CODE (insn
) == CALL_INSN
)
2207 && GET_CODE (insn
) != JUMP_INSN
2208 && GET_CODE (PATTERN (insn
)) != USE
2209 && GET_CODE (PATTERN (insn
)) != CLOBBER
)
2215 insn
= NEXT_INSN (insn
);
2221 /* Determine if a given basic block heads a simple IF-THEN or IF-THEN-ELSE
2222 block. If so, we'll try to convert the insns to not require the branch.
2223 Return TRUE if we were successful at converting the block. */
2226 find_if_block (ce_info
)
2227 struct ce_if_block
* ce_info
;
2229 basic_block test_bb
= ce_info
->test_bb
;
2230 basic_block then_bb
= ce_info
->then_bb
;
2231 basic_block else_bb
= ce_info
->else_bb
;
2232 basic_block join_bb
= NULL_BLOCK
;
2233 edge then_succ
= then_bb
->succ
;
2234 edge else_succ
= else_bb
->succ
;
2235 int then_predecessors
;
2236 int else_predecessors
;
2240 ce_info
->last_test_bb
= test_bb
;
2242 /* Discover if any fall through predecessors of the current test basic block
2243 were && tests (which jump to the else block) or || tests (which jump to
2245 if (HAVE_conditional_execution
&& reload_completed
2246 && test_bb
->pred
!= NULL_EDGE
2247 && test_bb
->pred
->pred_next
== NULL_EDGE
2248 && test_bb
->pred
->flags
== EDGE_FALLTHRU
)
2250 basic_block bb
= test_bb
->pred
->src
;
2251 basic_block target_bb
;
2252 int max_insns
= MAX_CONDITIONAL_EXECUTE
;
2255 /* Determine if the preceeding block is an && or || block. */
2256 if ((n_insns
= block_jumps_and_fallthru_p (bb
, else_bb
)) >= 0)
2258 ce_info
->and_and_p
= TRUE
;
2259 target_bb
= else_bb
;
2261 else if ((n_insns
= block_jumps_and_fallthru_p (bb
, then_bb
)) >= 0)
2263 ce_info
->and_and_p
= FALSE
;
2264 target_bb
= then_bb
;
2267 target_bb
= NULL_BLOCK
;
2269 if (target_bb
&& n_insns
<= max_insns
)
2271 int total_insns
= 0;
2274 ce_info
->last_test_bb
= test_bb
;
2276 /* Found at least one && or || block, look for more. */
2279 ce_info
->test_bb
= test_bb
= bb
;
2280 total_insns
+= n_insns
;
2283 if (bb
->pred
== NULL_EDGE
|| bb
->pred
->pred_next
!= NULL_EDGE
)
2287 n_insns
= block_jumps_and_fallthru_p (bb
, target_bb
);
2289 while (n_insns
>= 0 && (total_insns
+ n_insns
) <= max_insns
);
2291 ce_info
->num_multiple_test_blocks
= blocks
;
2292 ce_info
->num_multiple_test_insns
= total_insns
;
2294 if (ce_info
->and_and_p
)
2295 ce_info
->num_and_and_blocks
= blocks
;
2297 ce_info
->num_or_or_blocks
= blocks
;
2301 /* Count the number of edges the THEN and ELSE blocks have. */
2302 then_predecessors
= 0;
2303 for (cur_edge
= then_bb
->pred
;
2304 cur_edge
!= NULL_EDGE
;
2305 cur_edge
= cur_edge
->pred_next
)
2307 then_predecessors
++;
2308 if (cur_edge
->flags
& EDGE_COMPLEX
)
2312 else_predecessors
= 0;
2313 for (cur_edge
= else_bb
->pred
;
2314 cur_edge
!= NULL_EDGE
;
2315 cur_edge
= cur_edge
->pred_next
)
2317 else_predecessors
++;
2318 if (cur_edge
->flags
& EDGE_COMPLEX
)
2322 /* The THEN block of an IF-THEN combo must have exactly one predecessor,
2323 other than any || blocks which jump to the THEN block. */
2324 if ((then_predecessors
- ce_info
->num_or_or_blocks
) != 1)
2327 /* The THEN block of an IF-THEN combo must have zero or one successors. */
2328 if (then_succ
!= NULL_EDGE
2329 && (then_succ
->succ_next
!= NULL_EDGE
2330 || (then_succ
->flags
& EDGE_COMPLEX
)))
2333 /* If the THEN block has no successors, conditional execution can still
2334 make a conditional call. Don't do this unless the ELSE block has
2335 only one incoming edge -- the CFG manipulation is too ugly otherwise.
2336 Check for the last insn of the THEN block being an indirect jump, which
2337 is listed as not having any successors, but confuses the rest of the CE
2338 code processing. ??? we should fix this in the future. */
2339 if (then_succ
== NULL
)
2341 if (else_bb
->pred
->pred_next
== NULL_EDGE
)
2343 rtx last_insn
= then_bb
->end
;
2346 && GET_CODE (last_insn
) == NOTE
2347 && last_insn
!= then_bb
->head
)
2348 last_insn
= PREV_INSN (last_insn
);
2351 && GET_CODE (last_insn
) == JUMP_INSN
2352 && ! simplejump_p (last_insn
))
2356 else_bb
= NULL_BLOCK
;
2362 /* If the THEN block's successor is the other edge out of the TEST block,
2363 then we have an IF-THEN combo without an ELSE. */
2364 else if (then_succ
->dest
== else_bb
)
2367 else_bb
= NULL_BLOCK
;
2370 /* If the THEN and ELSE block meet in a subsequent block, and the ELSE
2371 has exactly one predecessor and one successor, and the outgoing edge
2372 is not complex, then we have an IF-THEN-ELSE combo. */
2373 else if (else_succ
!= NULL_EDGE
2374 && then_succ
->dest
== else_succ
->dest
2375 && else_bb
->pred
->pred_next
== NULL_EDGE
2376 && else_succ
->succ_next
== NULL_EDGE
2377 && ! (else_succ
->flags
& EDGE_COMPLEX
))
2378 join_bb
= else_succ
->dest
;
2380 /* Otherwise it is not an IF-THEN or IF-THEN-ELSE combination. */
2384 num_possible_if_blocks
++;
2388 fprintf (rtl_dump_file
, "\nIF-THEN%s block found, pass %d, start block %d [insn %d], then %d [%d]",
2389 (else_bb
) ? "-ELSE" : "",
2391 test_bb
->index
, (test_bb
->head
) ? (int)INSN_UID (test_bb
->head
) : -1,
2392 then_bb
->index
, (then_bb
->head
) ? (int)INSN_UID (then_bb
->head
) : -1);
2395 fprintf (rtl_dump_file
, ", else %d [%d]",
2396 else_bb
->index
, (else_bb
->head
) ? (int)INSN_UID (else_bb
->head
) : -1);
2398 fprintf (rtl_dump_file
, ", join %d [%d]",
2399 join_bb
->index
, (join_bb
->head
) ? (int)INSN_UID (join_bb
->head
) : -1);
2401 if (ce_info
->num_multiple_test_blocks
> 0)
2402 fprintf (rtl_dump_file
, ", %d %s block%s last test %d [%d]",
2403 ce_info
->num_multiple_test_blocks
,
2404 (ce_info
->and_and_p
) ? "&&" : "||",
2405 (ce_info
->num_multiple_test_blocks
== 1) ? "" : "s",
2406 ce_info
->last_test_bb
->index
,
2407 ((ce_info
->last_test_bb
->head
)
2408 ? (int)INSN_UID (ce_info
->last_test_bb
->head
)
2411 fputc ('\n', rtl_dump_file
);
2414 /* Make sure IF, THEN, and ELSE, blocks are adjacent. Actually, we get the
2415 first condition for free, since we've already asserted that there's a
2416 fallthru edge from IF to THEN. Likewise for the && and || blocks, since
2417 we checked the FALLTHRU flag, those are already adjacent to the last IF
2419 /* ??? As an enhancement, move the ELSE block. Have to deal with
2420 BLOCK notes, if by no other means than aborting the merge if they
2421 exist. Sticky enough I don't want to think about it now. */
2423 if (else_bb
&& (next
= next
->next_bb
) != else_bb
)
2425 if ((next
= next
->next_bb
) != join_bb
&& join_bb
!= EXIT_BLOCK_PTR
)
2433 /* Do the real work. */
2434 ce_info
->else_bb
= else_bb
;
2435 ce_info
->join_bb
= join_bb
;
2437 return process_if_block (ce_info
);
2440 /* Convert a branch over a trap, or a branch
2441 to a trap, into a conditional trap. */
2444 find_cond_trap (test_bb
, then_edge
, else_edge
)
2445 basic_block test_bb
;
2446 edge then_edge
, else_edge
;
2448 basic_block then_bb
= then_edge
->dest
;
2449 basic_block else_bb
= else_edge
->dest
;
2450 basic_block other_bb
, trap_bb
;
2451 rtx trap
, jump
, cond
, cond_earliest
, seq
;
2454 /* Locate the block with the trap instruction. */
2455 /* ??? While we look for no successors, we really ought to allow
2456 EH successors. Need to fix merge_if_block for that to work. */
2457 if ((trap
= block_has_only_trap (then_bb
)) != NULL
)
2458 trap_bb
= then_bb
, other_bb
= else_bb
;
2459 else if ((trap
= block_has_only_trap (else_bb
)) != NULL
)
2460 trap_bb
= else_bb
, other_bb
= then_bb
;
2466 fprintf (rtl_dump_file
, "\nTRAP-IF block found, start %d, trap %d\n",
2467 test_bb
->index
, trap_bb
->index
);
2470 /* If this is not a standard conditional jump, we can't parse it. */
2471 jump
= test_bb
->end
;
2472 cond
= noce_get_condition (jump
, &cond_earliest
);
2476 /* If the conditional jump is more than just a conditional jump, then
2477 we can not do if-conversion on this block. */
2478 if (! onlyjump_p (jump
))
2481 /* We must be comparing objects whose modes imply the size. */
2482 if (GET_MODE (XEXP (cond
, 0)) == BLKmode
)
2485 /* Reverse the comparison code, if necessary. */
2486 code
= GET_CODE (cond
);
2487 if (then_bb
== trap_bb
)
2489 code
= reversed_comparison_code (cond
, jump
);
2490 if (code
== UNKNOWN
)
2494 /* Attempt to generate the conditional trap. */
2495 seq
= gen_cond_trap (code
, XEXP (cond
, 0), XEXP (cond
, 1),
2496 TRAP_CODE (PATTERN (trap
)));
2500 /* Emit the new insns before cond_earliest. */
2501 emit_insn_before_scope (seq
, cond_earliest
, INSN_SCOPE (trap
));
2503 /* Delete the trap block if possible. */
2504 remove_edge (trap_bb
== then_bb
? then_edge
: else_edge
);
2505 if (trap_bb
->pred
== NULL
)
2507 if (post_dominators
)
2508 delete_from_dominance_info (post_dominators
, trap_bb
);
2509 flow_delete_block (trap_bb
);
2510 num_removed_blocks
++;
2513 /* If the non-trap block and the test are now adjacent, merge them.
2514 Otherwise we must insert a direct branch. */
2515 if (test_bb
->next_bb
== other_bb
)
2517 struct ce_if_block new_ce_info
;
2519 memset ((PTR
) &new_ce_info
, '\0', sizeof (new_ce_info
));
2520 new_ce_info
.test_bb
= test_bb
;
2521 new_ce_info
.then_bb
= NULL
;
2522 new_ce_info
.else_bb
= NULL
;
2523 new_ce_info
.join_bb
= other_bb
;
2524 merge_if_block (&new_ce_info
);
2530 lab
= JUMP_LABEL (jump
);
2531 newjump
= emit_jump_insn_after (gen_jump (lab
), jump
);
2532 LABEL_NUSES (lab
) += 1;
2533 JUMP_LABEL (newjump
) = lab
;
2534 emit_barrier_after (newjump
);
2542 /* Subroutine of find_cond_trap: if BB contains only a trap insn,
2546 block_has_only_trap (bb
)
2551 /* We're not the exit block. */
2552 if (bb
== EXIT_BLOCK_PTR
)
2555 /* The block must have no successors. */
2559 /* The only instruction in the THEN block must be the trap. */
2560 trap
= first_active_insn (bb
);
2561 if (! (trap
== bb
->end
2562 && GET_CODE (PATTERN (trap
)) == TRAP_IF
2563 && TRAP_CONDITION (PATTERN (trap
)) == const_true_rtx
))
2569 /* Look for IF-THEN-ELSE cases in which one of THEN or ELSE is
2570 transformable, but not necessarily the other. There need be no
2573 Return TRUE if we were successful at converting the block.
2575 Cases we'd like to look at:
2578 if (test) goto over; // x not live
2586 if (! test) goto label;
2589 if (test) goto E; // x not live
2603 (3) // This one's really only interesting for targets that can do
2604 // multiway branching, e.g. IA-64 BBB bundles. For other targets
2605 // it results in multiple branches on a cache line, which often
2606 // does not sit well with predictors.
2608 if (test1) goto E; // predicted not taken
2624 (A) Don't do (2) if the branch is predicted against the block we're
2625 eliminating. Do it anyway if we can eliminate a branch; this requires
2626 that the sole successor of the eliminated block postdominate the other
2629 (B) With CE, on (3) we can steal from both sides of the if, creating
2638 Again, this is most useful if J postdominates.
2640 (C) CE substitutes for helpful life information.
2642 (D) These heuristics need a lot of work. */
2644 /* Tests for case 1 above. */
2647 find_if_case_1 (test_bb
, then_edge
, else_edge
)
2648 basic_block test_bb
;
2649 edge then_edge
, else_edge
;
2651 basic_block then_bb
= then_edge
->dest
;
2652 basic_block else_bb
= else_edge
->dest
, new_bb
;
2653 edge then_succ
= then_bb
->succ
;
2656 /* THEN has one successor. */
2657 if (!then_succ
|| then_succ
->succ_next
!= NULL
)
2660 /* THEN does not fall through, but is not strange either. */
2661 if (then_succ
->flags
& (EDGE_COMPLEX
| EDGE_FALLTHRU
))
2664 /* THEN has one predecessor. */
2665 if (then_bb
->pred
->pred_next
!= NULL
)
2668 /* THEN must do something. */
2669 if (forwarder_block_p (then_bb
))
2672 num_possible_if_blocks
++;
2674 fprintf (rtl_dump_file
,
2675 "\nIF-CASE-1 found, start %d, then %d\n",
2676 test_bb
->index
, then_bb
->index
);
2678 /* THEN is small. */
2679 if (count_bb_insns (then_bb
) > BRANCH_COST
)
2682 /* Registers set are dead, or are predicable. */
2683 if (! dead_or_predicable (test_bb
, then_bb
, else_bb
,
2684 then_bb
->succ
->dest
, 1))
2687 /* Conversion went ok, including moving the insns and fixing up the
2688 jump. Adjust the CFG to match. */
2690 bitmap_operation (test_bb
->global_live_at_end
,
2691 else_bb
->global_live_at_start
,
2692 then_bb
->global_live_at_end
, BITMAP_IOR
);
2694 new_bb
= redirect_edge_and_branch_force (FALLTHRU_EDGE (test_bb
), else_bb
);
2695 then_bb_index
= then_bb
->index
;
2696 if (post_dominators
)
2697 delete_from_dominance_info (post_dominators
, then_bb
);
2698 flow_delete_block (then_bb
);
2700 /* Make rest of code believe that the newly created block is the THEN_BB
2701 block we removed. */
2704 new_bb
->index
= then_bb_index
;
2705 BASIC_BLOCK (then_bb_index
) = new_bb
;
2707 /* We've possibly created jump to next insn, cleanup_cfg will solve that
2710 num_removed_blocks
++;
2711 num_updated_if_blocks
++;
2716 /* Test for case 2 above. */
2719 find_if_case_2 (test_bb
, then_edge
, else_edge
)
2720 basic_block test_bb
;
2721 edge then_edge
, else_edge
;
2723 basic_block then_bb
= then_edge
->dest
;
2724 basic_block else_bb
= else_edge
->dest
;
2725 edge else_succ
= else_bb
->succ
;
2728 /* ELSE has one successor. */
2729 if (!else_succ
|| else_succ
->succ_next
!= NULL
)
2732 /* ELSE outgoing edge is not complex. */
2733 if (else_succ
->flags
& EDGE_COMPLEX
)
2736 /* ELSE has one predecessor. */
2737 if (else_bb
->pred
->pred_next
!= NULL
)
2740 /* THEN is not EXIT. */
2741 if (then_bb
->index
< 0)
2744 /* ELSE is predicted or SUCC(ELSE) postdominates THEN. */
2745 note
= find_reg_note (test_bb
->end
, REG_BR_PROB
, NULL_RTX
);
2746 if (note
&& INTVAL (XEXP (note
, 0)) >= REG_BR_PROB_BASE
/ 2)
2748 else if (else_succ
->dest
->index
< 0
2749 || dominated_by_p (post_dominators
, then_bb
,
2755 num_possible_if_blocks
++;
2757 fprintf (rtl_dump_file
,
2758 "\nIF-CASE-2 found, start %d, else %d\n",
2759 test_bb
->index
, else_bb
->index
);
2761 /* ELSE is small. */
2762 if (count_bb_insns (else_bb
) > BRANCH_COST
)
2765 /* Registers set are dead, or are predicable. */
2766 if (! dead_or_predicable (test_bb
, else_bb
, then_bb
, else_succ
->dest
, 0))
2769 /* Conversion went ok, including moving the insns and fixing up the
2770 jump. Adjust the CFG to match. */
2772 bitmap_operation (test_bb
->global_live_at_end
,
2773 then_bb
->global_live_at_start
,
2774 else_bb
->global_live_at_end
, BITMAP_IOR
);
2776 if (post_dominators
)
2777 delete_from_dominance_info (post_dominators
, else_bb
);
2778 flow_delete_block (else_bb
);
2780 num_removed_blocks
++;
2781 num_updated_if_blocks
++;
2783 /* ??? We may now fallthru from one of THEN's successors into a join
2784 block. Rerun cleanup_cfg? Examine things manually? Wait? */
2789 /* A subroutine of dead_or_predicable called through for_each_rtx.
2790 Return 1 if a memory is found. */
2793 find_memory (px
, data
)
2795 void *data ATTRIBUTE_UNUSED
;
2797 return GET_CODE (*px
) == MEM
;
2800 /* Used by the code above to perform the actual rtl transformations.
2801 Return TRUE if successful.
2803 TEST_BB is the block containing the conditional branch. MERGE_BB
2804 is the block containing the code to manipulate. NEW_DEST is the
2805 label TEST_BB should be branching to after the conversion.
2806 REVERSEP is true if the sense of the branch should be reversed. */
2809 dead_or_predicable (test_bb
, merge_bb
, other_bb
, new_dest
, reversep
)
2810 basic_block test_bb
, merge_bb
, other_bb
;
2811 basic_block new_dest
;
2814 rtx head
, end
, jump
, earliest
, old_dest
, new_label
= NULL_RTX
;
2816 jump
= test_bb
->end
;
2818 /* Find the extent of the real code in the merge block. */
2819 head
= merge_bb
->head
;
2820 end
= merge_bb
->end
;
2822 if (GET_CODE (head
) == CODE_LABEL
)
2823 head
= NEXT_INSN (head
);
2824 if (GET_CODE (head
) == NOTE
)
2828 head
= end
= NULL_RTX
;
2831 head
= NEXT_INSN (head
);
2834 if (GET_CODE (end
) == JUMP_INSN
)
2838 head
= end
= NULL_RTX
;
2841 end
= PREV_INSN (end
);
2844 /* Disable handling dead code by conditional execution if the machine needs
2845 to do anything funny with the tests, etc. */
2846 #ifndef IFCVT_MODIFY_TESTS
2847 if (HAVE_conditional_execution
)
2849 /* In the conditional execution case, we have things easy. We know
2850 the condition is reversable. We don't have to check life info,
2851 becase we're going to conditionally execute the code anyway.
2852 All that's left is making sure the insns involved can actually
2857 cond
= cond_exec_get_condition (jump
);
2861 prob_val
= find_reg_note (jump
, REG_BR_PROB
, NULL_RTX
);
2863 prob_val
= XEXP (prob_val
, 0);
2867 enum rtx_code rev
= reversed_comparison_code (cond
, jump
);
2870 cond
= gen_rtx_fmt_ee (rev
, GET_MODE (cond
), XEXP (cond
, 0),
2873 prob_val
= GEN_INT (REG_BR_PROB_BASE
- INTVAL (prob_val
));
2876 if (! cond_exec_process_insns ((ce_if_block_t
*)0, head
, end
, cond
,
2885 /* In the non-conditional execution case, we have to verify that there
2886 are no trapping operations, no calls, no references to memory, and
2887 that any registers modified are dead at the branch site. */
2889 rtx insn
, cond
, prev
;
2890 regset_head merge_set_head
, tmp_head
, test_live_head
, test_set_head
;
2891 regset merge_set
, tmp
, test_live
, test_set
;
2892 struct propagate_block_info
*pbi
;
2895 /* Check for no calls or trapping operations. */
2896 for (insn
= head
; ; insn
= NEXT_INSN (insn
))
2898 if (GET_CODE (insn
) == CALL_INSN
)
2902 if (may_trap_p (PATTERN (insn
)))
2905 /* ??? Even non-trapping memories such as stack frame
2906 references must be avoided. For stores, we collect
2907 no lifetime info; for reads, we'd have to assert
2908 true_dependence false against every store in the
2910 if (for_each_rtx (&PATTERN (insn
), find_memory
, NULL
))
2917 if (! any_condjump_p (jump
))
2920 /* Find the extent of the conditional. */
2921 cond
= noce_get_condition (jump
, &earliest
);
2926 MERGE_SET = set of registers set in MERGE_BB
2927 TEST_LIVE = set of registers live at EARLIEST
2928 TEST_SET = set of registers set between EARLIEST and the
2929 end of the block. */
2931 tmp
= INITIALIZE_REG_SET (tmp_head
);
2932 merge_set
= INITIALIZE_REG_SET (merge_set_head
);
2933 test_live
= INITIALIZE_REG_SET (test_live_head
);
2934 test_set
= INITIALIZE_REG_SET (test_set_head
);
2936 /* ??? bb->local_set is only valid during calculate_global_regs_live,
2937 so we must recompute usage for MERGE_BB. Not so bad, I suppose,
2938 since we've already asserted that MERGE_BB is small. */
2939 propagate_block (merge_bb
, tmp
, merge_set
, merge_set
, 0);
2941 /* For small register class machines, don't lengthen lifetimes of
2942 hard registers before reload. */
2943 if (SMALL_REGISTER_CLASSES
&& ! reload_completed
)
2945 EXECUTE_IF_SET_IN_BITMAP
2948 if (i
< FIRST_PSEUDO_REGISTER
2950 && ! global_regs
[i
])
2955 /* For TEST, we're interested in a range of insns, not a whole block.
2956 Moreover, we're interested in the insns live from OTHER_BB. */
2958 COPY_REG_SET (test_live
, other_bb
->global_live_at_start
);
2959 pbi
= init_propagate_block_info (test_bb
, test_live
, test_set
, test_set
,
2962 for (insn
= jump
; ; insn
= prev
)
2964 prev
= propagate_one_insn (pbi
, insn
);
2965 if (insn
== earliest
)
2969 free_propagate_block_info (pbi
);
2971 /* We can perform the transformation if
2972 MERGE_SET & (TEST_SET | TEST_LIVE)
2974 TEST_SET & merge_bb->global_live_at_start
2977 bitmap_operation (tmp
, test_set
, test_live
, BITMAP_IOR
);
2978 bitmap_operation (tmp
, tmp
, merge_set
, BITMAP_AND
);
2979 EXECUTE_IF_SET_IN_BITMAP(tmp
, 0, i
, fail
= 1);
2981 bitmap_operation (tmp
, test_set
, merge_bb
->global_live_at_start
,
2983 EXECUTE_IF_SET_IN_BITMAP(tmp
, 0, i
, fail
= 1);
2986 FREE_REG_SET (merge_set
);
2987 FREE_REG_SET (test_live
);
2988 FREE_REG_SET (test_set
);
2995 /* We don't want to use normal invert_jump or redirect_jump because
2996 we don't want to delete_insn called. Also, we want to do our own
2997 change group management. */
2999 old_dest
= JUMP_LABEL (jump
);
3000 if (other_bb
!= new_dest
)
3002 new_label
= block_label (new_dest
);
3004 ? ! invert_jump_1 (jump
, new_label
)
3005 : ! redirect_jump_1 (jump
, new_label
))
3009 if (! apply_change_group ())
3012 if (other_bb
!= new_dest
)
3015 LABEL_NUSES (old_dest
) -= 1;
3017 LABEL_NUSES (new_label
) += 1;
3018 JUMP_LABEL (jump
) = new_label
;
3020 invert_br_probabilities (jump
);
3022 redirect_edge_succ (BRANCH_EDGE (test_bb
), new_dest
);
3025 gcov_type count
, probability
;
3026 count
= BRANCH_EDGE (test_bb
)->count
;
3027 BRANCH_EDGE (test_bb
)->count
= FALLTHRU_EDGE (test_bb
)->count
;
3028 FALLTHRU_EDGE (test_bb
)->count
= count
;
3029 probability
= BRANCH_EDGE (test_bb
)->probability
;
3030 BRANCH_EDGE (test_bb
)->probability
3031 = FALLTHRU_EDGE (test_bb
)->probability
;
3032 FALLTHRU_EDGE (test_bb
)->probability
= probability
;
3033 update_br_prob_note (test_bb
);
3037 /* Move the insns out of MERGE_BB to before the branch. */
3040 if (end
== merge_bb
->end
)
3041 merge_bb
->end
= PREV_INSN (head
);
3043 if (squeeze_notes (&head
, &end
))
3046 reorder_insns (head
, end
, PREV_INSN (earliest
));
3049 /* Remove the jump and edge if we can. */
3050 if (other_bb
== new_dest
)
3053 remove_edge (BRANCH_EDGE (test_bb
));
3054 /* ??? Can't merge blocks here, as then_bb is still in use.
3055 At minimum, the merge will get done just before bb-reorder. */
3065 /* Main entry point for all if-conversion. */
3068 if_convert (x_life_data_ok
)
3074 num_possible_if_blocks
= 0;
3075 num_updated_if_blocks
= 0;
3076 num_removed_blocks
= 0;
3077 life_data_ok
= (x_life_data_ok
!= 0);
3079 /* Free up basic_block_for_insn so that we don't have to keep it
3080 up to date, either here or in merge_blocks_nomove. */
3081 free_basic_block_vars (1);
3083 /* Compute postdominators if we think we'll use them. */
3084 post_dominators
= NULL
;
3085 if (HAVE_conditional_execution
|| life_data_ok
)
3087 post_dominators
= calculate_dominance_info (CDI_POST_DOMINATORS
);
3092 /* Go through each of the basic blocks looking for things to convert. If we
3093 have conditional execution, we make multiple passes to allow us to handle
3094 IF-THEN{-ELSE} blocks within other IF-THEN{-ELSE} blocks. */
3098 cond_exec_changed_p
= FALSE
;
3101 #ifdef IFCVT_MULTIPLE_DUMPS
3102 if (rtl_dump_file
&& pass
> 1)
3103 fprintf (rtl_dump_file
, "\n\n========== Pass %d ==========\n", pass
);
3109 while ((new_bb
= find_if_header (bb
, pass
)))
3113 #ifdef IFCVT_MULTIPLE_DUMPS
3114 if (rtl_dump_file
&& cond_exec_changed_p
)
3115 print_rtl_with_bb (rtl_dump_file
, get_insns ());
3118 while (cond_exec_changed_p
);
3120 #ifdef IFCVT_MULTIPLE_DUMPS
3122 fprintf (rtl_dump_file
, "\n\n========== no more changes\n");
3125 if (post_dominators
)
3126 free_dominance_info (post_dominators
);
3129 fflush (rtl_dump_file
);
3131 clear_aux_for_blocks ();
3133 /* Rebuild life info for basic blocks that require it. */
3134 if (num_removed_blocks
&& life_data_ok
)
3136 /* If we allocated new pseudos, we must resize the array for sched1. */
3137 if (max_regno
< max_reg_num ())
3139 max_regno
= max_reg_num ();
3140 allocate_reg_info (max_regno
, FALSE
, FALSE
);
3142 update_life_info_in_dirty_blocks (UPDATE_LIFE_GLOBAL_RM_NOTES
,
3143 PROP_DEATH_NOTES
| PROP_SCAN_DEAD_CODE
3144 | PROP_KILL_DEAD_CODE
);
3147 /* Write the final stats. */
3148 if (rtl_dump_file
&& num_possible_if_blocks
> 0)
3150 fprintf (rtl_dump_file
,
3151 "\n%d possible IF blocks searched.\n",
3152 num_possible_if_blocks
);
3153 fprintf (rtl_dump_file
,
3154 "%d IF blocks converted.\n",
3155 num_updated_if_blocks
);
3156 fprintf (rtl_dump_file
,
3157 "%d basic blocks deleted.\n\n\n",
3158 num_removed_blocks
);
3161 #ifdef ENABLE_CHECKING
3162 verify_flow_info ();