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
28 #include "insn-config.h"
31 #include "hard-reg-set.h"
32 #include "basic-block.h"
40 #ifndef HAVE_conditional_execution
41 #define HAVE_conditional_execution 0
43 #ifndef HAVE_conditional_move
44 #define HAVE_conditional_move 0
55 #ifndef HAVE_conditional_trap
56 #define HAVE_conditional_trap 0
59 #ifndef MAX_CONDITIONAL_EXECUTE
60 #define MAX_CONDITIONAL_EXECUTE (BRANCH_COST + 1)
63 #define NULL_EDGE ((struct edge_def *)NULL)
64 #define NULL_BLOCK ((struct basic_block_def *)NULL)
66 /* # of IF-THEN or IF-THEN-ELSE blocks we looked at */
67 static int num_possible_if_blocks
;
69 /* # of IF-THEN or IF-THEN-ELSE blocks were converted to conditional
71 static int num_updated_if_blocks
;
73 /* # of basic blocks that were removed. */
74 static int num_removed_blocks
;
76 /* Whether conditional execution changes were made. */
77 static int cond_exec_changed_p
;
79 /* True if life data ok at present. */
80 static bool life_data_ok
;
82 /* The post-dominator relation on the original block numbers. */
83 static dominance_info post_dominators
;
85 /* Forward references. */
86 static int count_bb_insns
PARAMS ((basic_block
));
87 static rtx first_active_insn
PARAMS ((basic_block
));
88 static rtx last_active_insn
PARAMS ((basic_block
, int));
89 static int seq_contains_jump
PARAMS ((rtx
));
90 static basic_block block_fallthru
PARAMS ((basic_block
));
91 static int cond_exec_process_insns
PARAMS ((ce_if_block_t
*,
92 rtx
, rtx
, rtx
, rtx
, int));
93 static rtx cond_exec_get_condition
PARAMS ((rtx
));
94 static int cond_exec_process_if_block
PARAMS ((ce_if_block_t
*, int));
95 static rtx noce_get_condition
PARAMS ((rtx
, rtx
*));
96 static int noce_operand_ok
PARAMS ((rtx
));
97 static int noce_process_if_block
PARAMS ((ce_if_block_t
*));
98 static int process_if_block
PARAMS ((ce_if_block_t
*));
99 static void merge_if_block
PARAMS ((ce_if_block_t
*));
100 static int find_cond_trap
PARAMS ((basic_block
, edge
, edge
));
101 static basic_block find_if_header
PARAMS ((basic_block
, int));
102 static int block_jumps_and_fallthru_p
PARAMS ((basic_block
, basic_block
));
103 static int find_if_block
PARAMS ((ce_if_block_t
*));
104 static int find_if_case_1
PARAMS ((basic_block
, edge
, edge
));
105 static int find_if_case_2
PARAMS ((basic_block
, edge
, edge
));
106 static int find_memory
PARAMS ((rtx
*, void *));
107 static int dead_or_predicable
PARAMS ((basic_block
, basic_block
,
108 basic_block
, basic_block
, int));
109 static void noce_emit_move_insn
PARAMS ((rtx
, rtx
));
110 static rtx block_has_only_trap
PARAMS ((basic_block
));
112 /* Count the number of non-jump active insns in BB. */
123 if (GET_CODE (insn
) == CALL_INSN
|| GET_CODE (insn
) == INSN
)
128 insn
= NEXT_INSN (insn
);
134 /* Return the first non-jump active insn in the basic block. */
137 first_active_insn (bb
)
142 if (GET_CODE (insn
) == CODE_LABEL
)
146 insn
= NEXT_INSN (insn
);
149 while (GET_CODE (insn
) == NOTE
)
153 insn
= NEXT_INSN (insn
);
156 if (GET_CODE (insn
) == JUMP_INSN
)
162 /* Return the last non-jump active (non-jump) insn in the basic block. */
165 last_active_insn (bb
, skip_use_p
)
172 while (GET_CODE (insn
) == NOTE
173 || GET_CODE (insn
) == JUMP_INSN
175 && GET_CODE (insn
) == INSN
176 && GET_CODE (PATTERN (insn
)) == USE
))
180 insn
= PREV_INSN (insn
);
183 if (GET_CODE (insn
) == CODE_LABEL
)
189 /* It is possible, especially when having dealt with multi-word
190 arithmetic, for the expanders to have emitted jumps. Search
191 through the sequence and return TRUE if a jump exists so that
192 we can abort the conversion. */
195 seq_contains_jump (insn
)
200 if (GET_CODE (insn
) == JUMP_INSN
)
202 insn
= NEXT_INSN (insn
);
214 e
!= NULL_EDGE
&& (e
->flags
& EDGE_FALLTHRU
) == 0;
218 return (e
) ? e
->dest
: NULL_BLOCK
;
221 /* Go through a bunch of insns, converting them to conditional
222 execution format if possible. Return TRUE if all of the non-note
223 insns were processed. */
226 cond_exec_process_insns (ce_info
, start
, end
, test
, prob_val
, mod_ok
)
227 ce_if_block_t
*ce_info
; /* if block information */
228 rtx start
; /* first insn to look at */
229 rtx end
; /* last insn to look at */
230 rtx test
; /* conditional execution test */
231 rtx prob_val
; /* probability of branch taken. */
232 int mod_ok
; /* true if modifications ok last insn. */
234 int must_be_last
= FALSE
;
242 for (insn
= start
; ; insn
= NEXT_INSN (insn
))
244 if (GET_CODE (insn
) == NOTE
)
247 if (GET_CODE (insn
) != INSN
&& GET_CODE (insn
) != CALL_INSN
)
250 /* Remove USE insns that get in the way. */
251 if (reload_completed
&& GET_CODE (PATTERN (insn
)) == USE
)
253 /* ??? Ug. Actually unlinking the thing is problematic,
254 given what we'd have to coordinate with our callers. */
255 PUT_CODE (insn
, NOTE
);
256 NOTE_LINE_NUMBER (insn
) = NOTE_INSN_DELETED
;
257 NOTE_SOURCE_FILE (insn
) = 0;
261 /* Last insn wasn't last? */
265 if (modified_in_p (test
, insn
))
272 /* Now build the conditional form of the instruction. */
273 pattern
= PATTERN (insn
);
274 xtest
= copy_rtx (test
);
276 /* If this is already a COND_EXEC, rewrite the test to be an AND of the
278 if (GET_CODE (pattern
) == COND_EXEC
)
280 if (GET_MODE (xtest
) != GET_MODE (COND_EXEC_TEST (pattern
)))
283 xtest
= gen_rtx_AND (GET_MODE (xtest
), xtest
,
284 COND_EXEC_TEST (pattern
));
285 pattern
= COND_EXEC_CODE (pattern
);
288 pattern
= gen_rtx_COND_EXEC (VOIDmode
, xtest
, pattern
);
290 /* If the machine needs to modify the insn being conditionally executed,
291 say for example to force a constant integer operand into a temp
292 register, do so here. */
293 #ifdef IFCVT_MODIFY_INSN
294 IFCVT_MODIFY_INSN (ce_info
, pattern
, insn
);
299 validate_change (insn
, &PATTERN (insn
), pattern
, 1);
301 if (GET_CODE (insn
) == CALL_INSN
&& prob_val
)
302 validate_change (insn
, ®_NOTES (insn
),
303 alloc_EXPR_LIST (REG_BR_PROB
, prob_val
,
304 REG_NOTES (insn
)), 1);
314 /* Return the condition for a jump. Do not do any special processing. */
317 cond_exec_get_condition (jump
)
322 if (any_condjump_p (jump
))
323 test_if
= SET_SRC (pc_set (jump
));
326 cond
= XEXP (test_if
, 0);
328 /* If this branches to JUMP_LABEL when the condition is false,
329 reverse the condition. */
330 if (GET_CODE (XEXP (test_if
, 2)) == LABEL_REF
331 && XEXP (XEXP (test_if
, 2), 0) == JUMP_LABEL (jump
))
333 enum rtx_code rev
= reversed_comparison_code (cond
, jump
);
337 cond
= gen_rtx_fmt_ee (rev
, GET_MODE (cond
), XEXP (cond
, 0),
344 /* Given a simple IF-THEN or IF-THEN-ELSE block, attempt to convert it
345 to conditional execution. Return TRUE if we were successful at
346 converting the the block. */
349 cond_exec_process_if_block (ce_info
, do_multiple_p
)
350 ce_if_block_t
* ce_info
; /* if block information */
351 int do_multiple_p
; /* != 0 if we should handle && and || blocks */
353 basic_block test_bb
= ce_info
->test_bb
; /* last test block */
354 basic_block then_bb
= ce_info
->then_bb
; /* THEN */
355 basic_block else_bb
= ce_info
->else_bb
; /* ELSE or NULL */
356 rtx test_expr
; /* expression in IF_THEN_ELSE that is tested */
357 rtx then_start
; /* first insn in THEN block */
358 rtx then_end
; /* last insn + 1 in THEN block */
359 rtx else_start
= NULL_RTX
; /* first insn in ELSE block or NULL */
360 rtx else_end
= NULL_RTX
; /* last insn + 1 in ELSE block */
361 int max
; /* max # of insns to convert. */
362 int then_mod_ok
; /* whether conditional mods are ok in THEN */
363 rtx true_expr
; /* test for else block insns */
364 rtx false_expr
; /* test for then block insns */
365 rtx true_prob_val
; /* probability of else block */
366 rtx false_prob_val
; /* probability of then block */
368 enum rtx_code false_code
;
370 /* If test is comprised of && or || elements, and we've failed at handling
371 all of them together, just use the last test if it is the special case of
372 && elements without an ELSE block. */
373 if (!do_multiple_p
&& ce_info
->num_multiple_test_blocks
)
375 if (else_bb
|| ! ce_info
->and_and_p
)
378 ce_info
->test_bb
= test_bb
= ce_info
->last_test_bb
;
379 ce_info
->num_multiple_test_blocks
= 0;
380 ce_info
->num_and_and_blocks
= 0;
381 ce_info
->num_or_or_blocks
= 0;
384 /* Find the conditional jump to the ELSE or JOIN part, and isolate
386 test_expr
= cond_exec_get_condition (test_bb
->end
);
390 /* If the conditional jump is more than just a conditional jump,
391 then we can not do conditional execution conversion on this block. */
392 if (! onlyjump_p (test_bb
->end
))
395 /* Collect the bounds of where we're to search, skipping any labels, jumps
396 and notes at the beginning and end of the block. Then count the total
397 number of insns and see if it is small enough to convert. */
398 then_start
= first_active_insn (then_bb
);
399 then_end
= last_active_insn (then_bb
, TRUE
);
400 n_insns
= ce_info
->num_then_insns
= count_bb_insns (then_bb
);
401 max
= MAX_CONDITIONAL_EXECUTE
;
406 else_start
= first_active_insn (else_bb
);
407 else_end
= last_active_insn (else_bb
, TRUE
);
408 n_insns
+= ce_info
->num_else_insns
= count_bb_insns (else_bb
);
414 /* Map test_expr/test_jump into the appropriate MD tests to use on
415 the conditionally executed code. */
417 true_expr
= test_expr
;
419 false_code
= reversed_comparison_code (true_expr
, test_bb
->end
);
420 if (false_code
!= UNKNOWN
)
421 false_expr
= gen_rtx_fmt_ee (false_code
, GET_MODE (true_expr
),
422 XEXP (true_expr
, 0), XEXP (true_expr
, 1));
424 false_expr
= NULL_RTX
;
426 #ifdef IFCVT_MODIFY_TESTS
427 /* If the machine description needs to modify the tests, such as setting a
428 conditional execution register from a comparison, it can do so here. */
429 IFCVT_MODIFY_TESTS (true_expr
, false_expr
, test_bb
, then_bb
, else_bb
,
432 /* See if the conversion failed */
433 if (!true_expr
|| !false_expr
)
437 #ifdef IFCVT_MODIFY_TESTS
438 /* If the machine description needs to modify the tests, such as setting a
439 conditional execution register from a comparison, it can do so here. */
440 IFCVT_MODIFY_TESTS (ce_info
, true_expr
, false_expr
);
442 /* See if the conversion failed */
443 if (!true_expr
|| !false_expr
)
447 true_prob_val
= find_reg_note (test_bb
->end
, REG_BR_PROB
, NULL_RTX
);
450 true_prob_val
= XEXP (true_prob_val
, 0);
451 false_prob_val
= GEN_INT (REG_BR_PROB_BASE
- INTVAL (true_prob_val
));
454 false_prob_val
= NULL_RTX
;
456 /* If we have && or || tests, do them here. These tests are in the adjacent
457 blocks after the first block containing the test. */
458 if (ce_info
->num_multiple_test_blocks
> 0)
460 basic_block bb
= test_bb
;
461 basic_block last_test_bb
= ce_info
->last_test_bb
;
468 bb
= block_fallthru (bb
);
469 start
= first_active_insn (bb
);
470 end
= last_active_insn (bb
, TRUE
);
472 && ! cond_exec_process_insns (ce_info
, start
, end
, false_expr
,
473 false_prob_val
, FALSE
))
476 /* If the conditional jump is more than just a conditional jump, then
477 we can not do conditional execution conversion on this block. */
478 if (! onlyjump_p (bb
->end
))
481 /* Find the conditional jump and isolate the test. */
482 t
= cond_exec_get_condition (bb
->end
);
486 f
= gen_rtx_fmt_ee (reverse_condition (GET_CODE (t
)),
491 if (ce_info
->and_and_p
)
493 t
= gen_rtx_AND (GET_MODE (t
), true_expr
, t
);
494 f
= gen_rtx_IOR (GET_MODE (t
), false_expr
, f
);
498 t
= gen_rtx_IOR (GET_MODE (t
), true_expr
, t
);
499 f
= gen_rtx_AND (GET_MODE (t
), false_expr
, f
);
502 /* If the machine description needs to modify the tests, such as
503 setting a conditional execution register from a comparison, it can
505 #ifdef IFCVT_MODIFY_MULTIPLE_TESTS
506 IFCVT_MODIFY_MULTIPLE_TESTS (ce_info
, bb
, t
, f
);
508 /* See if the conversion failed */
516 while (bb
!= last_test_bb
);
519 /* For IF-THEN-ELSE blocks, we don't allow modifications of the test
520 on then THEN block. */
521 then_mod_ok
= (else_bb
== NULL_BLOCK
);
523 /* Go through the THEN and ELSE blocks converting the insns if possible
524 to conditional execution. */
528 || ! cond_exec_process_insns (ce_info
, then_start
, then_end
,
529 false_expr
, false_prob_val
,
533 if (else_bb
&& else_end
534 && ! cond_exec_process_insns (ce_info
, else_start
, else_end
,
535 true_expr
, true_prob_val
, TRUE
))
538 /* If we cannot apply the changes, fail. Do not go through the normal fail
539 processing, since apply_change_group will call cancel_changes. */
540 if (! apply_change_group ())
542 #ifdef IFCVT_MODIFY_CANCEL
543 /* Cancel any machine dependent changes. */
544 IFCVT_MODIFY_CANCEL (ce_info
);
549 #ifdef IFCVT_MODIFY_FINAL
550 /* Do any machine dependent final modifications */
551 IFCVT_MODIFY_FINAL (ce_info
);
554 /* Conversion succeeded. */
556 fprintf (rtl_dump_file
, "%d insn%s converted to conditional execution.\n",
557 n_insns
, (n_insns
== 1) ? " was" : "s were");
559 /* Merge the blocks! */
560 merge_if_block (ce_info
);
561 cond_exec_changed_p
= TRUE
;
565 #ifdef IFCVT_MODIFY_CANCEL
566 /* Cancel any machine dependent changes. */
567 IFCVT_MODIFY_CANCEL (ce_info
);
574 /* Used by noce_process_if_block to communicate with its subroutines.
576 The subroutines know that A and B may be evaluated freely. They
577 know that X is a register. They should insert new instructions
578 before cond_earliest. */
585 rtx jump
, cond
, cond_earliest
;
588 static rtx noce_emit_store_flag
PARAMS ((struct noce_if_info
*,
590 static int noce_try_store_flag
PARAMS ((struct noce_if_info
*));
591 static int noce_try_store_flag_inc
PARAMS ((struct noce_if_info
*));
592 static int noce_try_store_flag_constants
PARAMS ((struct noce_if_info
*));
593 static int noce_try_store_flag_mask
PARAMS ((struct noce_if_info
*));
594 static rtx noce_emit_cmove
PARAMS ((struct noce_if_info
*,
595 rtx
, enum rtx_code
, rtx
,
597 static int noce_try_cmove
PARAMS ((struct noce_if_info
*));
598 static int noce_try_cmove_arith
PARAMS ((struct noce_if_info
*));
599 static rtx noce_get_alt_condition
PARAMS ((struct noce_if_info
*,
601 static int noce_try_minmax
PARAMS ((struct noce_if_info
*));
602 static int noce_try_abs
PARAMS ((struct noce_if_info
*));
604 /* Helper function for noce_try_store_flag*. */
607 noce_emit_store_flag (if_info
, x
, reversep
, normalize
)
608 struct noce_if_info
*if_info
;
610 int reversep
, normalize
;
612 rtx cond
= if_info
->cond
;
616 cond_complex
= (! general_operand (XEXP (cond
, 0), VOIDmode
)
617 || ! general_operand (XEXP (cond
, 1), VOIDmode
));
619 /* If earliest == jump, or when the condition is complex, try to
620 build the store_flag insn directly. */
623 cond
= XEXP (SET_SRC (pc_set (if_info
->jump
)), 0);
626 code
= reversed_comparison_code (cond
, if_info
->jump
);
628 code
= GET_CODE (cond
);
630 if ((if_info
->cond_earliest
== if_info
->jump
|| cond_complex
)
631 && (normalize
== 0 || STORE_FLAG_VALUE
== normalize
))
635 tmp
= gen_rtx_fmt_ee (code
, GET_MODE (x
), XEXP (cond
, 0),
637 tmp
= gen_rtx_SET (VOIDmode
, x
, tmp
);
640 tmp
= emit_insn (tmp
);
642 if (recog_memoized (tmp
) >= 0)
648 if_info
->cond_earliest
= if_info
->jump
;
656 /* Don't even try if the comparison operands are weird. */
660 return emit_store_flag (x
, code
, XEXP (cond
, 0),
661 XEXP (cond
, 1), VOIDmode
,
662 (code
== LTU
|| code
== LEU
663 || code
== GEU
|| code
== GTU
), normalize
);
666 /* Emit instruction to move an rtx into STRICT_LOW_PART. */
668 noce_emit_move_insn (x
, y
)
671 enum machine_mode outmode
, inmode
;
675 if (GET_CODE (x
) != STRICT_LOW_PART
)
677 emit_move_insn (x
, y
);
682 inner
= XEXP (outer
, 0);
683 outmode
= GET_MODE (outer
);
684 inmode
= GET_MODE (inner
);
685 bitpos
= SUBREG_BYTE (outer
) * BITS_PER_UNIT
;
686 store_bit_field (inner
, GET_MODE_BITSIZE (outmode
), bitpos
, outmode
, y
,
687 GET_MODE_BITSIZE (inmode
));
690 /* Convert "if (test) x = 1; else x = 0".
692 Only try 0 and STORE_FLAG_VALUE here. Other combinations will be
693 tried in noce_try_store_flag_constants after noce_try_cmove has had
694 a go at the conversion. */
697 noce_try_store_flag (if_info
)
698 struct noce_if_info
*if_info
;
703 if (GET_CODE (if_info
->b
) == CONST_INT
704 && INTVAL (if_info
->b
) == STORE_FLAG_VALUE
705 && if_info
->a
== const0_rtx
)
707 else if (if_info
->b
== const0_rtx
708 && GET_CODE (if_info
->a
) == CONST_INT
709 && INTVAL (if_info
->a
) == STORE_FLAG_VALUE
710 && (reversed_comparison_code (if_info
->cond
, if_info
->jump
)
718 target
= noce_emit_store_flag (if_info
, if_info
->x
, reversep
, 0);
721 if (target
!= if_info
->x
)
722 noce_emit_move_insn (if_info
->x
, target
);
726 emit_insn_before_scope (seq
, if_info
->jump
, INSN_SCOPE (if_info
->insn_a
));
737 /* Convert "if (test) x = a; else x = b", for A and B constant. */
740 noce_try_store_flag_constants (if_info
)
741 struct noce_if_info
*if_info
;
745 HOST_WIDE_INT itrue
, ifalse
, diff
, tmp
;
746 int normalize
, can_reverse
;
747 enum machine_mode mode
;
750 && GET_CODE (if_info
->a
) == CONST_INT
751 && GET_CODE (if_info
->b
) == CONST_INT
)
753 mode
= GET_MODE (if_info
->x
);
754 ifalse
= INTVAL (if_info
->a
);
755 itrue
= INTVAL (if_info
->b
);
757 /* Make sure we can represent the difference between the two values. */
758 if ((itrue
- ifalse
> 0)
759 != ((ifalse
< 0) != (itrue
< 0) ? ifalse
< 0 : ifalse
< itrue
))
762 diff
= trunc_int_for_mode (itrue
- ifalse
, mode
);
764 can_reverse
= (reversed_comparison_code (if_info
->cond
, if_info
->jump
)
768 if (diff
== STORE_FLAG_VALUE
|| diff
== -STORE_FLAG_VALUE
)
770 else if (ifalse
== 0 && exact_log2 (itrue
) >= 0
771 && (STORE_FLAG_VALUE
== 1
772 || BRANCH_COST
>= 2))
774 else if (itrue
== 0 && exact_log2 (ifalse
) >= 0 && can_reverse
775 && (STORE_FLAG_VALUE
== 1 || BRANCH_COST
>= 2))
776 normalize
= 1, reversep
= 1;
778 && (STORE_FLAG_VALUE
== -1
779 || BRANCH_COST
>= 2))
781 else if (ifalse
== -1 && can_reverse
782 && (STORE_FLAG_VALUE
== -1 || BRANCH_COST
>= 2))
783 normalize
= -1, reversep
= 1;
784 else if ((BRANCH_COST
>= 2 && STORE_FLAG_VALUE
== -1)
792 tmp
= itrue
; itrue
= ifalse
; ifalse
= tmp
;
793 diff
= trunc_int_for_mode (-diff
, mode
);
797 target
= noce_emit_store_flag (if_info
, if_info
->x
, reversep
, normalize
);
804 /* if (test) x = 3; else x = 4;
805 => x = 3 + (test == 0); */
806 if (diff
== STORE_FLAG_VALUE
|| diff
== -STORE_FLAG_VALUE
)
808 target
= expand_simple_binop (mode
,
809 (diff
== STORE_FLAG_VALUE
811 GEN_INT (ifalse
), target
, if_info
->x
, 0,
815 /* if (test) x = 8; else x = 0;
816 => x = (test != 0) << 3; */
817 else if (ifalse
== 0 && (tmp
= exact_log2 (itrue
)) >= 0)
819 target
= expand_simple_binop (mode
, ASHIFT
,
820 target
, GEN_INT (tmp
), if_info
->x
, 0,
824 /* if (test) x = -1; else x = b;
825 => x = -(test != 0) | b; */
826 else if (itrue
== -1)
828 target
= expand_simple_binop (mode
, IOR
,
829 target
, GEN_INT (ifalse
), if_info
->x
, 0,
833 /* if (test) x = a; else x = b;
834 => x = (-(test != 0) & (b - a)) + a; */
837 target
= expand_simple_binop (mode
, AND
,
838 target
, GEN_INT (diff
), if_info
->x
, 0,
841 target
= expand_simple_binop (mode
, PLUS
,
842 target
, GEN_INT (ifalse
),
843 if_info
->x
, 0, OPTAB_WIDEN
);
852 if (target
!= if_info
->x
)
853 noce_emit_move_insn (if_info
->x
, target
);
858 if (seq_contains_jump (seq
))
861 emit_insn_before_scope (seq
, if_info
->jump
, INSN_SCOPE (if_info
->insn_a
));
869 /* Convert "if (test) foo++" into "foo += (test != 0)", and
870 similarly for "foo--". */
873 noce_try_store_flag_inc (if_info
)
874 struct noce_if_info
*if_info
;
877 int subtract
, normalize
;
883 /* Should be no `else' case to worry about. */
884 && if_info
->b
== if_info
->x
885 && GET_CODE (if_info
->a
) == PLUS
886 && (XEXP (if_info
->a
, 1) == const1_rtx
887 || XEXP (if_info
->a
, 1) == constm1_rtx
)
888 && rtx_equal_p (XEXP (if_info
->a
, 0), if_info
->x
)
889 && (reversed_comparison_code (if_info
->cond
, if_info
->jump
)
892 if (STORE_FLAG_VALUE
== INTVAL (XEXP (if_info
->a
, 1)))
893 subtract
= 0, normalize
= 0;
894 else if (-STORE_FLAG_VALUE
== INTVAL (XEXP (if_info
->a
, 1)))
895 subtract
= 1, normalize
= 0;
897 subtract
= 0, normalize
= INTVAL (XEXP (if_info
->a
, 1));
901 target
= noce_emit_store_flag (if_info
,
902 gen_reg_rtx (GET_MODE (if_info
->x
)),
906 target
= expand_simple_binop (GET_MODE (if_info
->x
),
907 subtract
? MINUS
: PLUS
,
908 if_info
->x
, target
, if_info
->x
,
912 if (target
!= if_info
->x
)
913 noce_emit_move_insn (if_info
->x
, target
);
918 if (seq_contains_jump (seq
))
921 emit_insn_before_scope (seq
, if_info
->jump
,
922 INSN_SCOPE (if_info
->insn_a
));
933 /* Convert "if (test) x = 0;" to "x &= -(test == 0);" */
936 noce_try_store_flag_mask (if_info
)
937 struct noce_if_info
*if_info
;
945 || STORE_FLAG_VALUE
== -1)
946 && ((if_info
->a
== const0_rtx
947 && rtx_equal_p (if_info
->b
, if_info
->x
))
948 || ((reversep
= (reversed_comparison_code (if_info
->cond
,
951 && if_info
->b
== const0_rtx
952 && rtx_equal_p (if_info
->a
, if_info
->x
))))
955 target
= noce_emit_store_flag (if_info
,
956 gen_reg_rtx (GET_MODE (if_info
->x
)),
959 target
= expand_simple_binop (GET_MODE (if_info
->x
), AND
,
960 if_info
->x
, target
, if_info
->x
, 0,
965 if (target
!= if_info
->x
)
966 noce_emit_move_insn (if_info
->x
, target
);
971 if (seq_contains_jump (seq
))
974 emit_insn_before_scope (seq
, if_info
->jump
,
975 INSN_SCOPE (if_info
->insn_a
));
986 /* Helper function for noce_try_cmove and noce_try_cmove_arith. */
989 noce_emit_cmove (if_info
, x
, code
, cmp_a
, cmp_b
, vfalse
, vtrue
)
990 struct noce_if_info
*if_info
;
991 rtx x
, cmp_a
, cmp_b
, vfalse
, vtrue
;
994 /* If earliest == jump, try to build the cmove insn directly.
995 This is helpful when combine has created some complex condition
996 (like for alpha's cmovlbs) that we can't hope to regenerate
997 through the normal interface. */
999 if (if_info
->cond_earliest
== if_info
->jump
)
1003 tmp
= gen_rtx_fmt_ee (code
, GET_MODE (if_info
->cond
), cmp_a
, cmp_b
);
1004 tmp
= gen_rtx_IF_THEN_ELSE (GET_MODE (x
), tmp
, vtrue
, vfalse
);
1005 tmp
= gen_rtx_SET (VOIDmode
, x
, tmp
);
1008 tmp
= emit_insn (tmp
);
1010 if (recog_memoized (tmp
) >= 0)
1022 /* Don't even try if the comparison operands are weird. */
1023 if (! general_operand (cmp_a
, GET_MODE (cmp_a
))
1024 || ! general_operand (cmp_b
, GET_MODE (cmp_b
)))
1027 #if HAVE_conditional_move
1028 return emit_conditional_move (x
, code
, cmp_a
, cmp_b
, VOIDmode
,
1029 vtrue
, vfalse
, GET_MODE (x
),
1030 (code
== LTU
|| code
== GEU
1031 || code
== LEU
|| code
== GTU
));
1033 /* We'll never get here, as noce_process_if_block doesn't call the
1034 functions involved. Ifdef code, however, should be discouraged
1035 because it leads to typos in the code not selected. However,
1036 emit_conditional_move won't exist either. */
1041 /* Try only simple constants and registers here. More complex cases
1042 are handled in noce_try_cmove_arith after noce_try_store_flag_arith
1043 has had a go at it. */
1046 noce_try_cmove (if_info
)
1047 struct noce_if_info
*if_info
;
1052 if ((CONSTANT_P (if_info
->a
) || register_operand (if_info
->a
, VOIDmode
))
1053 && (CONSTANT_P (if_info
->b
) || register_operand (if_info
->b
, VOIDmode
)))
1057 code
= GET_CODE (if_info
->cond
);
1058 target
= noce_emit_cmove (if_info
, if_info
->x
, code
,
1059 XEXP (if_info
->cond
, 0),
1060 XEXP (if_info
->cond
, 1),
1061 if_info
->a
, if_info
->b
);
1065 if (target
!= if_info
->x
)
1066 noce_emit_move_insn (if_info
->x
, target
);
1070 emit_insn_before_scope (seq
, if_info
->jump
,
1071 INSN_SCOPE (if_info
->insn_a
));
1084 /* Try more complex cases involving conditional_move. */
1087 noce_try_cmove_arith (if_info
)
1088 struct noce_if_info
*if_info
;
1098 /* A conditional move from two memory sources is equivalent to a
1099 conditional on their addresses followed by a load. Don't do this
1100 early because it'll screw alias analysis. Note that we've
1101 already checked for no side effects. */
1102 if (! no_new_pseudos
&& cse_not_expected
1103 && GET_CODE (a
) == MEM
&& GET_CODE (b
) == MEM
1104 && BRANCH_COST
>= 5)
1108 x
= gen_reg_rtx (Pmode
);
1112 /* ??? We could handle this if we knew that a load from A or B could
1113 not fault. This is also true if we've already loaded
1114 from the address along the path from ENTRY. */
1115 else if (may_trap_p (a
) || may_trap_p (b
))
1118 /* if (test) x = a + b; else x = c - d;
1125 code
= GET_CODE (if_info
->cond
);
1126 insn_a
= if_info
->insn_a
;
1127 insn_b
= if_info
->insn_b
;
1129 /* Possibly rearrange operands to make things come out more natural. */
1130 if (reversed_comparison_code (if_info
->cond
, if_info
->jump
) != UNKNOWN
)
1133 if (rtx_equal_p (b
, x
))
1135 else if (general_operand (b
, GET_MODE (b
)))
1140 code
= reversed_comparison_code (if_info
->cond
, if_info
->jump
);
1141 tmp
= a
, a
= b
, b
= tmp
;
1142 tmp
= insn_a
, insn_a
= insn_b
, insn_b
= tmp
;
1148 /* If either operand is complex, load it into a register first.
1149 The best way to do this is to copy the original insn. In this
1150 way we preserve any clobbers etc that the insn may have had.
1151 This is of course not possible in the IS_MEM case. */
1152 if (! general_operand (a
, GET_MODE (a
)))
1157 goto end_seq_and_fail
;
1161 tmp
= gen_reg_rtx (GET_MODE (a
));
1162 tmp
= emit_insn (gen_rtx_SET (VOIDmode
, tmp
, a
));
1165 goto end_seq_and_fail
;
1168 a
= gen_reg_rtx (GET_MODE (a
));
1169 tmp
= copy_rtx (insn_a
);
1170 set
= single_set (tmp
);
1172 tmp
= emit_insn (PATTERN (tmp
));
1174 if (recog_memoized (tmp
) < 0)
1175 goto end_seq_and_fail
;
1177 if (! general_operand (b
, GET_MODE (b
)))
1182 goto end_seq_and_fail
;
1186 tmp
= gen_reg_rtx (GET_MODE (b
));
1187 tmp
= emit_insn (gen_rtx_SET (VOIDmode
, tmp
, b
));
1190 goto end_seq_and_fail
;
1193 b
= gen_reg_rtx (GET_MODE (b
));
1194 tmp
= copy_rtx (insn_b
);
1195 set
= single_set (tmp
);
1197 tmp
= emit_insn (PATTERN (tmp
));
1199 if (recog_memoized (tmp
) < 0)
1200 goto end_seq_and_fail
;
1203 target
= noce_emit_cmove (if_info
, x
, code
, XEXP (if_info
->cond
, 0),
1204 XEXP (if_info
->cond
, 1), a
, b
);
1207 goto end_seq_and_fail
;
1209 /* If we're handling a memory for above, emit the load now. */
1212 tmp
= gen_rtx_MEM (GET_MODE (if_info
->x
), target
);
1214 /* Copy over flags as appropriate. */
1215 if (MEM_VOLATILE_P (if_info
->a
) || MEM_VOLATILE_P (if_info
->b
))
1216 MEM_VOLATILE_P (tmp
) = 1;
1217 if (MEM_IN_STRUCT_P (if_info
->a
) && MEM_IN_STRUCT_P (if_info
->b
))
1218 MEM_IN_STRUCT_P (tmp
) = 1;
1219 if (MEM_SCALAR_P (if_info
->a
) && MEM_SCALAR_P (if_info
->b
))
1220 MEM_SCALAR_P (tmp
) = 1;
1221 if (MEM_ALIAS_SET (if_info
->a
) == MEM_ALIAS_SET (if_info
->b
))
1222 set_mem_alias_set (tmp
, MEM_ALIAS_SET (if_info
->a
));
1224 MIN (MEM_ALIGN (if_info
->a
), MEM_ALIGN (if_info
->b
)));
1226 noce_emit_move_insn (if_info
->x
, tmp
);
1228 else if (target
!= x
)
1229 noce_emit_move_insn (x
, target
);
1233 emit_insn_before_scope (tmp
, if_info
->jump
, INSN_SCOPE (if_info
->insn_a
));
1241 /* For most cases, the simplified condition we found is the best
1242 choice, but this is not the case for the min/max/abs transforms.
1243 For these we wish to know that it is A or B in the condition. */
1246 noce_get_alt_condition (if_info
, target
, earliest
)
1247 struct noce_if_info
*if_info
;
1251 rtx cond
, set
, insn
;
1254 /* If target is already mentioned in the known condition, return it. */
1255 if (reg_mentioned_p (target
, if_info
->cond
))
1257 *earliest
= if_info
->cond_earliest
;
1258 return if_info
->cond
;
1261 set
= pc_set (if_info
->jump
);
1262 cond
= XEXP (SET_SRC (set
), 0);
1264 = GET_CODE (XEXP (SET_SRC (set
), 2)) == LABEL_REF
1265 && XEXP (XEXP (SET_SRC (set
), 2), 0) == JUMP_LABEL (if_info
->jump
);
1267 /* If we're looking for a constant, try to make the conditional
1268 have that constant in it. There are two reasons why it may
1269 not have the constant we want:
1271 1. GCC may have needed to put the constant in a register, because
1272 the target can't compare directly against that constant. For
1273 this case, we look for a SET immediately before the comparison
1274 that puts a constant in that register.
1276 2. GCC may have canonicalized the conditional, for example
1277 replacing "if x < 4" with "if x <= 3". We can undo that (or
1278 make equivalent types of changes) to get the constants we need
1279 if they're off by one in the right direction. */
1281 if (GET_CODE (target
) == CONST_INT
)
1283 enum rtx_code code
= GET_CODE (if_info
->cond
);
1284 rtx op_a
= XEXP (if_info
->cond
, 0);
1285 rtx op_b
= XEXP (if_info
->cond
, 1);
1288 /* First, look to see if we put a constant in a register. */
1289 prev_insn
= PREV_INSN (if_info
->cond_earliest
);
1291 && INSN_P (prev_insn
)
1292 && GET_CODE (PATTERN (prev_insn
)) == SET
)
1294 rtx src
= find_reg_equal_equiv_note (prev_insn
);
1296 src
= SET_SRC (PATTERN (prev_insn
));
1297 if (GET_CODE (src
) == CONST_INT
)
1299 if (rtx_equal_p (op_a
, SET_DEST (PATTERN (prev_insn
))))
1301 else if (rtx_equal_p (op_b
, SET_DEST (PATTERN (prev_insn
))))
1304 if (GET_CODE (op_a
) == CONST_INT
)
1309 code
= swap_condition (code
);
1314 /* Now, look to see if we can get the right constant by
1315 adjusting the conditional. */
1316 if (GET_CODE (op_b
) == CONST_INT
)
1318 HOST_WIDE_INT desired_val
= INTVAL (target
);
1319 HOST_WIDE_INT actual_val
= INTVAL (op_b
);
1324 if (actual_val
== desired_val
+ 1)
1327 op_b
= GEN_INT (desired_val
);
1331 if (actual_val
== desired_val
- 1)
1334 op_b
= GEN_INT (desired_val
);
1338 if (actual_val
== desired_val
- 1)
1341 op_b
= GEN_INT (desired_val
);
1345 if (actual_val
== desired_val
+ 1)
1348 op_b
= GEN_INT (desired_val
);
1356 /* If we made any changes, generate a new conditional that is
1357 equivalent to what we started with, but has the right
1359 if (code
!= GET_CODE (if_info
->cond
)
1360 || op_a
!= XEXP (if_info
->cond
, 0)
1361 || op_b
!= XEXP (if_info
->cond
, 1))
1363 cond
= gen_rtx_fmt_ee (code
, GET_MODE (cond
), op_a
, op_b
);
1364 *earliest
= if_info
->cond_earliest
;
1369 cond
= canonicalize_condition (if_info
->jump
, cond
, reverse
,
1371 if (! cond
|| ! reg_mentioned_p (target
, cond
))
1374 /* We almost certainly searched back to a different place.
1375 Need to re-verify correct lifetimes. */
1377 /* X may not be mentioned in the range (cond_earliest, jump]. */
1378 for (insn
= if_info
->jump
; insn
!= *earliest
; insn
= PREV_INSN (insn
))
1379 if (INSN_P (insn
) && reg_mentioned_p (if_info
->x
, insn
))
1382 /* A and B may not be modified in the range [cond_earliest, jump). */
1383 for (insn
= *earliest
; insn
!= if_info
->jump
; insn
= NEXT_INSN (insn
))
1385 && (modified_in_p (if_info
->a
, insn
)
1386 || modified_in_p (if_info
->b
, insn
)))
1392 /* Convert "if (a < b) x = a; else x = b;" to "x = min(a, b);", etc. */
1395 noce_try_minmax (if_info
)
1396 struct noce_if_info
*if_info
;
1398 rtx cond
, earliest
, target
, seq
;
1399 enum rtx_code code
, op
;
1402 /* ??? Can't guarantee that expand_binop won't create pseudos. */
1406 /* ??? Reject modes with NaNs or signed zeros since we don't know how
1407 they will be resolved with an SMIN/SMAX. It wouldn't be too hard
1408 to get the target to tell us... */
1409 if (HONOR_SIGNED_ZEROS (GET_MODE (if_info
->x
))
1410 || HONOR_NANS (GET_MODE (if_info
->x
)))
1413 cond
= noce_get_alt_condition (if_info
, if_info
->a
, &earliest
);
1417 /* Verify the condition is of the form we expect, and canonicalize
1418 the comparison code. */
1419 code
= GET_CODE (cond
);
1420 if (rtx_equal_p (XEXP (cond
, 0), if_info
->a
))
1422 if (! rtx_equal_p (XEXP (cond
, 1), if_info
->b
))
1425 else if (rtx_equal_p (XEXP (cond
, 1), if_info
->a
))
1427 if (! rtx_equal_p (XEXP (cond
, 0), if_info
->b
))
1429 code
= swap_condition (code
);
1434 /* Determine what sort of operation this is. Note that the code is for
1435 a taken branch, so the code->operation mapping appears backwards. */
1468 target
= expand_simple_binop (GET_MODE (if_info
->x
), op
,
1469 if_info
->a
, if_info
->b
,
1470 if_info
->x
, unsignedp
, OPTAB_WIDEN
);
1476 if (target
!= if_info
->x
)
1477 noce_emit_move_insn (if_info
->x
, target
);
1482 if (seq_contains_jump (seq
))
1485 emit_insn_before_scope (seq
, if_info
->jump
, INSN_SCOPE (if_info
->insn_a
));
1486 if_info
->cond
= cond
;
1487 if_info
->cond_earliest
= earliest
;
1492 /* Convert "if (a < 0) x = -a; else x = a;" to "x = abs(a);", etc. */
1495 noce_try_abs (if_info
)
1496 struct noce_if_info
*if_info
;
1498 rtx cond
, earliest
, target
, seq
, a
, b
, c
;
1501 /* ??? Can't guarantee that expand_binop won't create pseudos. */
1505 /* Recognize A and B as constituting an ABS or NABS. */
1508 if (GET_CODE (a
) == NEG
&& rtx_equal_p (XEXP (a
, 0), b
))
1510 else if (GET_CODE (b
) == NEG
&& rtx_equal_p (XEXP (b
, 0), a
))
1512 c
= a
; a
= b
; b
= c
;
1518 cond
= noce_get_alt_condition (if_info
, b
, &earliest
);
1522 /* Verify the condition is of the form we expect. */
1523 if (rtx_equal_p (XEXP (cond
, 0), b
))
1525 else if (rtx_equal_p (XEXP (cond
, 1), b
))
1530 /* Verify that C is zero. Search backward through the block for
1531 a REG_EQUAL note if necessary. */
1534 rtx insn
, note
= NULL
;
1535 for (insn
= earliest
;
1536 insn
!= if_info
->test_bb
->head
;
1537 insn
= PREV_INSN (insn
))
1539 && ((note
= find_reg_note (insn
, REG_EQUAL
, c
))
1540 || (note
= find_reg_note (insn
, REG_EQUIV
, c
))))
1546 if (GET_CODE (c
) == MEM
1547 && GET_CODE (XEXP (c
, 0)) == SYMBOL_REF
1548 && CONSTANT_POOL_ADDRESS_P (XEXP (c
, 0)))
1549 c
= get_pool_constant (XEXP (c
, 0));
1551 /* Work around funny ideas get_condition has wrt canonicalization.
1552 Note that these rtx constants are known to be CONST_INT, and
1553 therefore imply integer comparisons. */
1554 if (c
== constm1_rtx
&& GET_CODE (cond
) == GT
)
1556 else if (c
== const1_rtx
&& GET_CODE (cond
) == LT
)
1558 else if (c
!= CONST0_RTX (GET_MODE (b
)))
1561 /* Determine what sort of operation this is. */
1562 switch (GET_CODE (cond
))
1581 target
= expand_simple_unop (GET_MODE (if_info
->x
), ABS
, b
, if_info
->x
, 0);
1583 /* ??? It's a quandry whether cmove would be better here, especially
1584 for integers. Perhaps combine will clean things up. */
1585 if (target
&& negate
)
1586 target
= expand_simple_unop (GET_MODE (target
), NEG
, target
, if_info
->x
, 0);
1594 if (target
!= if_info
->x
)
1595 noce_emit_move_insn (if_info
->x
, target
);
1600 if (seq_contains_jump (seq
))
1603 emit_insn_before_scope (seq
, if_info
->jump
, INSN_SCOPE (if_info
->insn_a
));
1604 if_info
->cond
= cond
;
1605 if_info
->cond_earliest
= earliest
;
1610 /* Similar to get_condition, only the resulting condition must be
1611 valid at JUMP, instead of at EARLIEST. */
1614 noce_get_condition (jump
, earliest
)
1618 rtx cond
, set
, tmp
, insn
;
1621 if (! any_condjump_p (jump
))
1624 set
= pc_set (jump
);
1626 /* If this branches to JUMP_LABEL when the condition is false,
1627 reverse the condition. */
1628 reverse
= (GET_CODE (XEXP (SET_SRC (set
), 2)) == LABEL_REF
1629 && XEXP (XEXP (SET_SRC (set
), 2), 0) == JUMP_LABEL (jump
));
1631 /* If the condition variable is a register and is MODE_INT, accept it. */
1633 cond
= XEXP (SET_SRC (set
), 0);
1634 tmp
= XEXP (cond
, 0);
1635 if (REG_P (tmp
) && GET_MODE_CLASS (GET_MODE (tmp
)) == MODE_INT
)
1640 cond
= gen_rtx_fmt_ee (reverse_condition (GET_CODE (cond
)),
1641 GET_MODE (cond
), tmp
, XEXP (cond
, 1));
1645 /* Otherwise, fall back on canonicalize_condition to do the dirty
1646 work of manipulating MODE_CC values and COMPARE rtx codes. */
1648 tmp
= canonicalize_condition (jump
, cond
, reverse
, earliest
, NULL_RTX
);
1652 /* We are going to insert code before JUMP, not before EARLIEST.
1653 We must therefore be certain that the given condition is valid
1654 at JUMP by virtue of not having been modified since. */
1655 for (insn
= *earliest
; insn
!= jump
; insn
= NEXT_INSN (insn
))
1656 if (INSN_P (insn
) && modified_in_p (tmp
, insn
))
1661 /* The condition was modified. See if we can get a partial result
1662 that doesn't follow all the reversals. Perhaps combine can fold
1663 them together later. */
1664 tmp
= XEXP (tmp
, 0);
1665 if (!REG_P (tmp
) || GET_MODE_CLASS (GET_MODE (tmp
)) != MODE_INT
)
1667 tmp
= canonicalize_condition (jump
, cond
, reverse
, earliest
, tmp
);
1671 /* For sanity's sake, re-validate the new result. */
1672 for (insn
= *earliest
; insn
!= jump
; insn
= NEXT_INSN (insn
))
1673 if (INSN_P (insn
) && modified_in_p (tmp
, insn
))
1679 /* Return true if OP is ok for if-then-else processing. */
1682 noce_operand_ok (op
)
1685 /* We special-case memories, so handle any of them with
1686 no address side effects. */
1687 if (GET_CODE (op
) == MEM
)
1688 return ! side_effects_p (XEXP (op
, 0));
1690 if (side_effects_p (op
))
1693 return ! may_trap_p (op
);
1696 /* Given a simple IF-THEN or IF-THEN-ELSE block, attempt to convert it
1697 without using conditional execution. Return TRUE if we were
1698 successful at converting the the block. */
1701 noce_process_if_block (ce_info
)
1702 struct ce_if_block
* ce_info
;
1704 basic_block test_bb
= ce_info
->test_bb
; /* test block */
1705 basic_block then_bb
= ce_info
->then_bb
; /* THEN */
1706 basic_block else_bb
= ce_info
->else_bb
; /* ELSE or NULL */
1707 struct noce_if_info if_info
;
1710 rtx orig_x
, x
, a
, b
;
1711 rtx jump
, cond
, insn
;
1713 /* We're looking for patterns of the form
1715 (1) if (...) x = a; else x = b;
1716 (2) x = b; if (...) x = a;
1717 (3) if (...) x = a; // as if with an initial x = x.
1719 The later patterns require jumps to be more expensive.
1721 ??? For future expansion, look for multiple X in such patterns. */
1723 /* If test is comprised of && or || elements, don't handle it unless it is
1724 the special case of && elements without an ELSE block. */
1725 if (ce_info
->num_multiple_test_blocks
)
1727 if (else_bb
|| ! ce_info
->and_and_p
)
1730 ce_info
->test_bb
= test_bb
= ce_info
->last_test_bb
;
1731 ce_info
->num_multiple_test_blocks
= 0;
1732 ce_info
->num_and_and_blocks
= 0;
1733 ce_info
->num_or_or_blocks
= 0;
1736 /* If this is not a standard conditional jump, we can't parse it. */
1737 jump
= test_bb
->end
;
1738 cond
= noce_get_condition (jump
, &if_info
.cond_earliest
);
1742 /* If the conditional jump is more than just a conditional
1743 jump, then we can not do if-conversion on this block. */
1744 if (! onlyjump_p (jump
))
1747 /* We must be comparing objects whose modes imply the size. */
1748 if (GET_MODE (XEXP (cond
, 0)) == BLKmode
)
1751 /* Look for one of the potential sets. */
1752 insn_a
= first_active_insn (then_bb
);
1754 || insn_a
!= last_active_insn (then_bb
, FALSE
)
1755 || (set_a
= single_set (insn_a
)) == NULL_RTX
)
1758 x
= SET_DEST (set_a
);
1759 a
= SET_SRC (set_a
);
1761 /* Look for the other potential set. Make sure we've got equivalent
1763 /* ??? This is overconservative. Storing to two different mems is
1764 as easy as conditionally computing the address. Storing to a
1765 single mem merely requires a scratch memory to use as one of the
1766 destination addresses; often the memory immediately below the
1767 stack pointer is available for this. */
1771 insn_b
= first_active_insn (else_bb
);
1773 || insn_b
!= last_active_insn (else_bb
, FALSE
)
1774 || (set_b
= single_set (insn_b
)) == NULL_RTX
1775 || ! rtx_equal_p (x
, SET_DEST (set_b
)))
1780 insn_b
= prev_nonnote_insn (if_info
.cond_earliest
);
1782 || GET_CODE (insn_b
) != INSN
1783 || (set_b
= single_set (insn_b
)) == NULL_RTX
1784 || ! rtx_equal_p (x
, SET_DEST (set_b
))
1785 || reg_mentioned_p (x
, cond
)
1786 || reg_mentioned_p (x
, a
)
1787 || reg_mentioned_p (x
, SET_SRC (set_b
)))
1788 insn_b
= set_b
= NULL_RTX
;
1790 b
= (set_b
? SET_SRC (set_b
) : x
);
1792 /* X may not be mentioned in the range (cond_earliest, jump]. */
1793 for (insn
= jump
; insn
!= if_info
.cond_earliest
; insn
= PREV_INSN (insn
))
1794 if (INSN_P (insn
) && reg_mentioned_p (x
, insn
))
1797 /* A and B may not be modified in the range [cond_earliest, jump). */
1798 for (insn
= if_info
.cond_earliest
; insn
!= jump
; insn
= NEXT_INSN (insn
))
1800 && (modified_in_p (a
, insn
) || modified_in_p (b
, insn
)))
1803 /* Only operate on register destinations, and even then avoid extending
1804 the lifetime of hard registers on small register class machines. */
1806 if (GET_CODE (x
) != REG
1807 || (SMALL_REGISTER_CLASSES
1808 && REGNO (x
) < FIRST_PSEUDO_REGISTER
))
1812 x
= gen_reg_rtx (GET_MODE (GET_CODE (x
) == STRICT_LOW_PART
1813 ? XEXP (x
, 0) : x
));
1816 /* Don't operate on sources that may trap or are volatile. */
1817 if (! noce_operand_ok (a
) || ! noce_operand_ok (b
))
1820 /* Set up the info block for our subroutines. */
1821 if_info
.test_bb
= test_bb
;
1822 if_info
.cond
= cond
;
1823 if_info
.jump
= jump
;
1824 if_info
.insn_a
= insn_a
;
1825 if_info
.insn_b
= insn_b
;
1830 /* Try optimizations in some approximation of a useful order. */
1831 /* ??? Should first look to see if X is live incoming at all. If it
1832 isn't, we don't need anything but an unconditional set. */
1834 /* Look and see if A and B are really the same. Avoid creating silly
1835 cmove constructs that no one will fix up later. */
1836 if (rtx_equal_p (a
, b
))
1838 /* If we have an INSN_B, we don't have to create any new rtl. Just
1839 move the instruction that we already have. If we don't have an
1840 INSN_B, that means that A == X, and we've got a noop move. In
1841 that case don't do anything and let the code below delete INSN_A. */
1842 if (insn_b
&& else_bb
)
1846 if (else_bb
&& insn_b
== else_bb
->end
)
1847 else_bb
->end
= PREV_INSN (insn_b
);
1848 reorder_insns (insn_b
, insn_b
, PREV_INSN (if_info
.cond_earliest
));
1850 /* If there was a REG_EQUAL note, delete it since it may have been
1851 true due to this insn being after a jump. */
1852 if ((note
= find_reg_note (insn_b
, REG_EQUAL
, NULL_RTX
)) != 0)
1853 remove_note (insn_b
, note
);
1857 /* If we have "x = b; if (...) x = a;", and x has side-effects, then
1858 x must be executed twice. */
1859 else if (insn_b
&& side_effects_p (orig_x
))
1866 if (noce_try_store_flag (&if_info
))
1868 if (noce_try_minmax (&if_info
))
1870 if (noce_try_abs (&if_info
))
1872 if (HAVE_conditional_move
1873 && noce_try_cmove (&if_info
))
1875 if (! HAVE_conditional_execution
)
1877 if (noce_try_store_flag_constants (&if_info
))
1879 if (noce_try_store_flag_inc (&if_info
))
1881 if (noce_try_store_flag_mask (&if_info
))
1883 if (HAVE_conditional_move
1884 && noce_try_cmove_arith (&if_info
))
1891 /* The original sets may now be killed. */
1892 delete_insn (insn_a
);
1894 /* Several special cases here: First, we may have reused insn_b above,
1895 in which case insn_b is now NULL. Second, we want to delete insn_b
1896 if it came from the ELSE block, because follows the now correct
1897 write that appears in the TEST block. However, if we got insn_b from
1898 the TEST block, it may in fact be loading data needed for the comparison.
1899 We'll let life_analysis remove the insn if it's really dead. */
1900 if (insn_b
&& else_bb
)
1901 delete_insn (insn_b
);
1903 /* The new insns will have been inserted before cond_earliest. We should
1904 be able to remove the jump with impunity, but the condition itself may
1905 have been modified by gcse to be shared across basic blocks. */
1908 /* If we used a temporary, fix it up now. */
1912 noce_emit_move_insn (copy_rtx (orig_x
), x
);
1913 insn_b
= get_insns ();
1916 emit_insn_after_scope (insn_b
, test_bb
->end
, INSN_SCOPE (insn_a
));
1919 /* Merge the blocks! */
1920 merge_if_block (ce_info
);
1925 /* Attempt to convert an IF-THEN or IF-THEN-ELSE block into
1926 straight line code. Return true if successful. */
1929 process_if_block (ce_info
)
1930 struct ce_if_block
* ce_info
;
1932 if (! reload_completed
1933 && noce_process_if_block (ce_info
))
1936 if (HAVE_conditional_execution
&& reload_completed
)
1938 /* If we have && and || tests, try to first handle combining the && and
1939 || tests into the conditional code, and if that fails, go back and
1940 handle it without the && and ||, which at present handles the && case
1941 if there was no ELSE block. */
1942 if (cond_exec_process_if_block (ce_info
, TRUE
))
1945 if (ce_info
->num_multiple_test_blocks
)
1949 if (cond_exec_process_if_block (ce_info
, FALSE
))
1957 /* Merge the blocks and mark for local life update. */
1960 merge_if_block (ce_info
)
1961 struct ce_if_block
* ce_info
;
1963 basic_block test_bb
= ce_info
->test_bb
; /* last test block */
1964 basic_block then_bb
= ce_info
->then_bb
; /* THEN */
1965 basic_block else_bb
= ce_info
->else_bb
; /* ELSE or NULL */
1966 basic_block join_bb
= ce_info
->join_bb
; /* join block */
1967 basic_block combo_bb
;
1969 /* All block merging is done into the lower block numbers. */
1973 /* Merge any basic blocks to handle && and || subtests. Each of
1974 the blocks are on the fallthru path from the predecessor block. */
1975 if (ce_info
->num_multiple_test_blocks
> 0)
1977 basic_block bb
= test_bb
;
1978 basic_block last_test_bb
= ce_info
->last_test_bb
;
1979 basic_block fallthru
= block_fallthru (bb
);
1984 fallthru
= block_fallthru (bb
);
1985 if (post_dominators
)
1986 delete_from_dominance_info (post_dominators
, bb
);
1987 merge_blocks_nomove (combo_bb
, bb
);
1988 num_removed_blocks
++;
1990 while (bb
!= last_test_bb
);
1993 /* Merge TEST block into THEN block. Normally the THEN block won't have a
1994 label, but it might if there were || tests. That label's count should be
1995 zero, and it normally should be removed. */
1999 if (combo_bb
->global_live_at_end
)
2000 COPY_REG_SET (combo_bb
->global_live_at_end
,
2001 then_bb
->global_live_at_end
);
2002 if (post_dominators
)
2003 delete_from_dominance_info (post_dominators
, then_bb
);
2004 merge_blocks_nomove (combo_bb
, then_bb
);
2005 num_removed_blocks
++;
2008 /* The ELSE block, if it existed, had a label. That label count
2009 will almost always be zero, but odd things can happen when labels
2010 get their addresses taken. */
2013 if (post_dominators
)
2014 delete_from_dominance_info (post_dominators
, else_bb
);
2015 merge_blocks_nomove (combo_bb
, else_bb
);
2016 num_removed_blocks
++;
2019 /* If there was no join block reported, that means it was not adjacent
2020 to the others, and so we cannot merge them. */
2024 rtx last
= combo_bb
->end
;
2026 /* The outgoing edge for the current COMBO block should already
2027 be correct. Verify this. */
2028 if (combo_bb
->succ
== NULL_EDGE
)
2030 if (find_reg_note (last
, REG_NORETURN
, NULL
))
2032 else if (GET_CODE (last
) == INSN
2033 && GET_CODE (PATTERN (last
)) == TRAP_IF
2034 && TRAP_CONDITION (PATTERN (last
)) == const_true_rtx
)
2040 /* There should still be something at the end of the THEN or ELSE
2041 blocks taking us to our final destination. */
2042 else if (GET_CODE (last
) == JUMP_INSN
)
2044 else if (combo_bb
->succ
->dest
== EXIT_BLOCK_PTR
2045 && GET_CODE (last
) == CALL_INSN
2046 && SIBLING_CALL_P (last
))
2048 else if ((combo_bb
->succ
->flags
& EDGE_EH
)
2049 && can_throw_internal (last
))
2055 /* The JOIN block may have had quite a number of other predecessors too.
2056 Since we've already merged the TEST, THEN and ELSE blocks, we should
2057 have only one remaining edge from our if-then-else diamond. If there
2058 is more than one remaining edge, it must come from elsewhere. There
2059 may be zero incoming edges if the THEN block didn't actually join
2060 back up (as with a call to abort). */
2061 else if ((join_bb
->pred
== NULL
2062 || join_bb
->pred
->pred_next
== NULL
)
2063 && join_bb
!= EXIT_BLOCK_PTR
)
2065 /* We can merge the JOIN. */
2066 if (combo_bb
->global_live_at_end
)
2067 COPY_REG_SET (combo_bb
->global_live_at_end
,
2068 join_bb
->global_live_at_end
);
2070 if (post_dominators
)
2071 delete_from_dominance_info (post_dominators
, join_bb
);
2072 merge_blocks_nomove (combo_bb
, join_bb
);
2073 num_removed_blocks
++;
2077 /* We cannot merge the JOIN. */
2079 /* The outgoing edge for the current COMBO block should already
2080 be correct. Verify this. */
2081 if (combo_bb
->succ
->succ_next
!= NULL_EDGE
2082 || combo_bb
->succ
->dest
!= join_bb
)
2085 /* Remove the jump and cruft from the end of the COMBO block. */
2086 if (join_bb
!= EXIT_BLOCK_PTR
)
2087 tidy_fallthru_edge (combo_bb
->succ
, combo_bb
, join_bb
);
2090 num_updated_if_blocks
++;
2093 /* Find a block ending in a simple IF condition and try to transform it
2094 in some way. When converting a multi-block condition, put the new code
2095 in the first such block and delete the rest. Return a pointer to this
2096 first block if some transformation was done. Return NULL otherwise. */
2099 find_if_header (test_bb
, pass
)
2100 basic_block test_bb
;
2103 ce_if_block_t ce_info
;
2107 /* The kind of block we're looking for has exactly two successors. */
2108 if ((then_edge
= test_bb
->succ
) == NULL_EDGE
2109 || (else_edge
= then_edge
->succ_next
) == NULL_EDGE
2110 || else_edge
->succ_next
!= NULL_EDGE
)
2113 /* Neither edge should be abnormal. */
2114 if ((then_edge
->flags
& EDGE_COMPLEX
)
2115 || (else_edge
->flags
& EDGE_COMPLEX
))
2118 /* The THEN edge is canonically the one that falls through. */
2119 if (then_edge
->flags
& EDGE_FALLTHRU
)
2121 else if (else_edge
->flags
& EDGE_FALLTHRU
)
2124 else_edge
= then_edge
;
2128 /* Otherwise this must be a multiway branch of some sort. */
2131 memset ((PTR
) &ce_info
, '\0', sizeof (ce_info
));
2132 ce_info
.test_bb
= test_bb
;
2133 ce_info
.then_bb
= then_edge
->dest
;
2134 ce_info
.else_bb
= else_edge
->dest
;
2135 ce_info
.pass
= pass
;
2137 #ifdef IFCVT_INIT_EXTRA_FIELDS
2138 IFCVT_INIT_EXTRA_FIELDS (&ce_info
);
2141 if (find_if_block (&ce_info
))
2144 if (HAVE_trap
&& HAVE_conditional_trap
2145 && find_cond_trap (test_bb
, then_edge
, else_edge
))
2149 && (! HAVE_conditional_execution
|| reload_completed
))
2151 if (find_if_case_1 (test_bb
, then_edge
, else_edge
))
2153 if (find_if_case_2 (test_bb
, then_edge
, else_edge
))
2161 fprintf (rtl_dump_file
, "Conversion succeeded on pass %d.\n", pass
);
2162 return ce_info
.test_bb
;
2165 /* Return true if a block has two edges, one of which falls through to the next
2166 block, and the other jumps to a specific block, so that we can tell if the
2167 block is part of an && test or an || test. Returns either -1 or the number
2168 of non-note, non-jump, non-USE/CLOBBER insns in the block. */
2171 block_jumps_and_fallthru_p (cur_bb
, target_bb
)
2173 basic_block target_bb
;
2176 int fallthru_p
= FALSE
;
2182 if (!cur_bb
|| !target_bb
)
2185 /* If no edges, obviously it doesn't jump or fallthru. */
2186 if (cur_bb
->succ
== NULL_EDGE
)
2189 for (cur_edge
= cur_bb
->succ
;
2190 cur_edge
!= NULL_EDGE
;
2191 cur_edge
= cur_edge
->succ_next
)
2193 if (cur_edge
->flags
& EDGE_COMPLEX
)
2194 /* Anything complex isn't what we want. */
2197 else if (cur_edge
->flags
& EDGE_FALLTHRU
)
2200 else if (cur_edge
->dest
== target_bb
)
2207 if ((jump_p
& fallthru_p
) == 0)
2210 /* Don't allow calls in the block, since this is used to group && and ||
2211 together for conditional execution support. ??? we should support
2212 conditional execution support across calls for IA-64 some day, but
2213 for now it makes the code simpler. */
2215 insn
= cur_bb
->head
;
2217 while (insn
!= NULL_RTX
)
2219 if (GET_CODE (insn
) == CALL_INSN
)
2223 && GET_CODE (insn
) != JUMP_INSN
2224 && GET_CODE (PATTERN (insn
)) != USE
2225 && GET_CODE (PATTERN (insn
)) != CLOBBER
)
2231 insn
= NEXT_INSN (insn
);
2237 /* Determine if a given basic block heads a simple IF-THEN or IF-THEN-ELSE
2238 block. If so, we'll try to convert the insns to not require the branch.
2239 Return TRUE if we were successful at converting the the block. */
2242 find_if_block (ce_info
)
2243 struct ce_if_block
* ce_info
;
2245 basic_block test_bb
= ce_info
->test_bb
;
2246 basic_block then_bb
= ce_info
->then_bb
;
2247 basic_block else_bb
= ce_info
->else_bb
;
2248 basic_block join_bb
= NULL_BLOCK
;
2249 edge then_succ
= then_bb
->succ
;
2250 edge else_succ
= else_bb
->succ
;
2251 int then_predecessors
;
2252 int else_predecessors
;
2256 ce_info
->last_test_bb
= test_bb
;
2258 /* Discover if any fall through predecessors of the current test basic block
2259 were && tests (which jump to the else block) or || tests (which jump to
2261 if (HAVE_conditional_execution
&& reload_completed
2262 && test_bb
->pred
!= NULL_EDGE
2263 && test_bb
->pred
->pred_next
== NULL_EDGE
2264 && test_bb
->pred
->flags
== EDGE_FALLTHRU
)
2266 basic_block bb
= test_bb
->pred
->src
;
2267 basic_block target_bb
;
2268 int max_insns
= MAX_CONDITIONAL_EXECUTE
;
2271 /* Determine if the preceeding block is an && or || block. */
2272 if ((n_insns
= block_jumps_and_fallthru_p (bb
, else_bb
)) >= 0)
2274 ce_info
->and_and_p
= TRUE
;
2275 target_bb
= else_bb
;
2277 else if ((n_insns
= block_jumps_and_fallthru_p (bb
, then_bb
)) >= 0)
2279 ce_info
->and_and_p
= FALSE
;
2280 target_bb
= then_bb
;
2283 target_bb
= NULL_BLOCK
;
2285 if (target_bb
&& n_insns
<= max_insns
)
2287 int total_insns
= 0;
2290 ce_info
->last_test_bb
= test_bb
;
2292 /* Found at least one && or || block, look for more. */
2295 ce_info
->test_bb
= test_bb
= bb
;
2296 total_insns
+= n_insns
;
2299 if (bb
->pred
== NULL_EDGE
|| bb
->pred
->pred_next
!= NULL_EDGE
)
2303 n_insns
= block_jumps_and_fallthru_p (bb
, target_bb
);
2305 while (n_insns
>= 0 && (total_insns
+ n_insns
) <= max_insns
);
2307 ce_info
->num_multiple_test_blocks
= blocks
;
2308 ce_info
->num_multiple_test_insns
= total_insns
;
2310 if (ce_info
->and_and_p
)
2311 ce_info
->num_and_and_blocks
= blocks
;
2313 ce_info
->num_or_or_blocks
= blocks
;
2317 /* Count the number of edges the THEN and ELSE blocks have. */
2318 then_predecessors
= 0;
2319 for (cur_edge
= then_bb
->pred
;
2320 cur_edge
!= NULL_EDGE
;
2321 cur_edge
= cur_edge
->pred_next
)
2323 then_predecessors
++;
2324 if (cur_edge
->flags
& EDGE_COMPLEX
)
2328 else_predecessors
= 0;
2329 for (cur_edge
= else_bb
->pred
;
2330 cur_edge
!= NULL_EDGE
;
2331 cur_edge
= cur_edge
->pred_next
)
2333 else_predecessors
++;
2334 if (cur_edge
->flags
& EDGE_COMPLEX
)
2338 /* The THEN block of an IF-THEN combo must have exactly one predecessor,
2339 other than any || blocks which jump to the THEN block. */
2340 if ((then_predecessors
- ce_info
->num_or_or_blocks
) != 1)
2343 /* The THEN block of an IF-THEN combo must have zero or one successors. */
2344 if (then_succ
!= NULL_EDGE
2345 && (then_succ
->succ_next
!= NULL_EDGE
2346 || (then_succ
->flags
& EDGE_COMPLEX
)))
2349 /* If the THEN block has no successors, conditional execution can still
2350 make a conditional call. Don't do this unless the ELSE block has
2351 only one incoming edge -- the CFG manipulation is too ugly otherwise.
2352 Check for the last insn of the THEN block being an indirect jump, which
2353 is listed as not having any successors, but confuses the rest of the CE
2354 code processing. ??? we should fix this in the future. */
2355 if (then_succ
== NULL
)
2357 if (else_bb
->pred
->pred_next
== NULL_EDGE
)
2359 rtx last_insn
= then_bb
->end
;
2362 && GET_CODE (last_insn
) == NOTE
2363 && last_insn
!= then_bb
->head
)
2364 last_insn
= PREV_INSN (last_insn
);
2367 && GET_CODE (last_insn
) == JUMP_INSN
2368 && ! simplejump_p (last_insn
))
2372 else_bb
= NULL_BLOCK
;
2378 /* If the THEN block's successor is the other edge out of the TEST block,
2379 then we have an IF-THEN combo without an ELSE. */
2380 else if (then_succ
->dest
== else_bb
)
2383 else_bb
= NULL_BLOCK
;
2386 /* If the THEN and ELSE block meet in a subsequent block, and the ELSE
2387 has exactly one predecessor and one successor, and the outgoing edge
2388 is not complex, then we have an IF-THEN-ELSE combo. */
2389 else if (else_succ
!= NULL_EDGE
2390 && then_succ
->dest
== else_succ
->dest
2391 && else_bb
->pred
->pred_next
== NULL_EDGE
2392 && else_succ
->succ_next
== NULL_EDGE
2393 && ! (else_succ
->flags
& EDGE_COMPLEX
))
2394 join_bb
= else_succ
->dest
;
2396 /* Otherwise it is not an IF-THEN or IF-THEN-ELSE combination. */
2400 num_possible_if_blocks
++;
2404 fprintf (rtl_dump_file
, "\nIF-THEN%s block found, pass %d, start block %d [insn %d], then %d [%d]",
2405 (else_bb
) ? "-ELSE" : "",
2407 test_bb
->index
, (test_bb
->head
) ? (int)INSN_UID (test_bb
->head
) : -1,
2408 then_bb
->index
, (then_bb
->head
) ? (int)INSN_UID (then_bb
->head
) : -1);
2411 fprintf (rtl_dump_file
, ", else %d [%d]",
2412 else_bb
->index
, (else_bb
->head
) ? (int)INSN_UID (else_bb
->head
) : -1);
2414 fprintf (rtl_dump_file
, ", join %d [%d]",
2415 join_bb
->index
, (join_bb
->head
) ? (int)INSN_UID (join_bb
->head
) : -1);
2417 if (ce_info
->num_multiple_test_blocks
> 0)
2418 fprintf (rtl_dump_file
, ", %d %s block%s last test %d [%d]",
2419 ce_info
->num_multiple_test_blocks
,
2420 (ce_info
->and_and_p
) ? "&&" : "||",
2421 (ce_info
->num_multiple_test_blocks
== 1) ? "" : "s",
2422 ce_info
->last_test_bb
->index
,
2423 ((ce_info
->last_test_bb
->head
)
2424 ? (int)INSN_UID (ce_info
->last_test_bb
->head
)
2427 fputc ('\n', rtl_dump_file
);
2430 /* Make sure IF, THEN, and ELSE, blocks are adjacent. Actually, we get the
2431 first condition for free, since we've already asserted that there's a
2432 fallthru edge from IF to THEN. Likewise for the && and || blocks, since
2433 we checked the FALLTHRU flag, those are already adjacent to the last IF
2435 /* ??? As an enhancement, move the ELSE block. Have to deal with
2436 BLOCK notes, if by no other means than aborting the merge if they
2437 exist. Sticky enough I don't want to think about it now. */
2439 if (else_bb
&& (next
= next
->next_bb
) != else_bb
)
2441 if ((next
= next
->next_bb
) != join_bb
&& join_bb
!= EXIT_BLOCK_PTR
)
2449 /* Do the real work. */
2450 ce_info
->else_bb
= else_bb
;
2451 ce_info
->join_bb
= join_bb
;
2453 return process_if_block (ce_info
);
2456 /* Convert a branch over a trap, or a branch
2457 to a trap, into a conditional trap. */
2460 find_cond_trap (test_bb
, then_edge
, else_edge
)
2461 basic_block test_bb
;
2462 edge then_edge
, else_edge
;
2464 basic_block then_bb
= then_edge
->dest
;
2465 basic_block else_bb
= else_edge
->dest
;
2466 basic_block other_bb
, trap_bb
;
2467 rtx trap
, jump
, cond
, cond_earliest
, seq
;
2470 /* Locate the block with the trap instruction. */
2471 /* ??? While we look for no successors, we really ought to allow
2472 EH successors. Need to fix merge_if_block for that to work. */
2473 if ((trap
= block_has_only_trap (then_bb
)) != NULL
)
2474 trap_bb
= then_bb
, other_bb
= else_bb
;
2475 else if ((trap
= block_has_only_trap (else_bb
)) != NULL
)
2476 trap_bb
= else_bb
, other_bb
= then_bb
;
2482 fprintf (rtl_dump_file
, "\nTRAP-IF block found, start %d, trap %d\n",
2483 test_bb
->index
, trap_bb
->index
);
2486 /* If this is not a standard conditional jump, we can't parse it. */
2487 jump
= test_bb
->end
;
2488 cond
= noce_get_condition (jump
, &cond_earliest
);
2492 /* If the conditional jump is more than just a conditional jump, then
2493 we can not do if-conversion on this block. */
2494 if (! onlyjump_p (jump
))
2497 /* We must be comparing objects whose modes imply the size. */
2498 if (GET_MODE (XEXP (cond
, 0)) == BLKmode
)
2501 /* Reverse the comparison code, if necessary. */
2502 code
= GET_CODE (cond
);
2503 if (then_bb
== trap_bb
)
2505 code
= reversed_comparison_code (cond
, jump
);
2506 if (code
== UNKNOWN
)
2510 /* Attempt to generate the conditional trap. */
2511 seq
= gen_cond_trap (code
, XEXP (cond
, 0), XEXP (cond
, 1),
2512 TRAP_CODE (PATTERN (trap
)));
2516 /* Emit the new insns before cond_earliest. */
2517 emit_insn_before_scope (seq
, cond_earliest
, INSN_SCOPE (trap
));
2519 /* Delete the trap block if possible. */
2520 remove_edge (trap_bb
== then_bb
? then_edge
: else_edge
);
2521 if (trap_bb
->pred
== NULL
)
2523 if (post_dominators
)
2524 delete_from_dominance_info (post_dominators
, trap_bb
);
2525 flow_delete_block (trap_bb
);
2526 num_removed_blocks
++;
2529 /* If the non-trap block and the test are now adjacent, merge them.
2530 Otherwise we must insert a direct branch. */
2531 if (test_bb
->next_bb
== other_bb
)
2533 struct ce_if_block new_ce_info
;
2535 memset ((PTR
) &new_ce_info
, '\0', sizeof (new_ce_info
));
2536 new_ce_info
.test_bb
= test_bb
;
2537 new_ce_info
.then_bb
= NULL
;
2538 new_ce_info
.else_bb
= NULL
;
2539 new_ce_info
.join_bb
= other_bb
;
2540 merge_if_block (&new_ce_info
);
2546 lab
= JUMP_LABEL (jump
);
2547 newjump
= emit_jump_insn_after (gen_jump (lab
), jump
);
2548 LABEL_NUSES (lab
) += 1;
2549 JUMP_LABEL (newjump
) = lab
;
2550 emit_barrier_after (newjump
);
2558 /* Subroutine of find_cond_trap: if BB contains only a trap insn,
2562 block_has_only_trap (bb
)
2567 /* We're not the exit block. */
2568 if (bb
== EXIT_BLOCK_PTR
)
2571 /* The block must have no successors. */
2575 /* The only instruction in the THEN block must be the trap. */
2576 trap
= first_active_insn (bb
);
2577 if (! (trap
== bb
->end
2578 && GET_CODE (PATTERN (trap
)) == TRAP_IF
2579 && TRAP_CONDITION (PATTERN (trap
)) == const_true_rtx
))
2585 /* Look for IF-THEN-ELSE cases in which one of THEN or ELSE is
2586 transformable, but not necessarily the other. There need be no
2589 Return TRUE if we were successful at converting the the block.
2591 Cases we'd like to look at:
2594 if (test) goto over; // x not live
2602 if (! test) goto label;
2605 if (test) goto E; // x not live
2619 (3) // This one's really only interesting for targets that can do
2620 // multiway branching, e.g. IA-64 BBB bundles. For other targets
2621 // it results in multiple branches on a cache line, which often
2622 // does not sit well with predictors.
2624 if (test1) goto E; // predicted not taken
2640 (A) Don't do (2) if the branch is predicted against the block we're
2641 eliminating. Do it anyway if we can eliminate a branch; this requires
2642 that the sole successor of the eliminated block postdominate the other
2645 (B) With CE, on (3) we can steal from both sides of the if, creating
2654 Again, this is most useful if J postdominates.
2656 (C) CE substitutes for helpful life information.
2658 (D) These heuristics need a lot of work. */
2660 /* Tests for case 1 above. */
2663 find_if_case_1 (test_bb
, then_edge
, else_edge
)
2664 basic_block test_bb
;
2665 edge then_edge
, else_edge
;
2667 basic_block then_bb
= then_edge
->dest
;
2668 basic_block else_bb
= else_edge
->dest
, new_bb
;
2669 edge then_succ
= then_bb
->succ
;
2672 /* THEN has one successor. */
2673 if (!then_succ
|| then_succ
->succ_next
!= NULL
)
2676 /* THEN does not fall through, but is not strange either. */
2677 if (then_succ
->flags
& (EDGE_COMPLEX
| EDGE_FALLTHRU
))
2680 /* THEN has one predecessor. */
2681 if (then_bb
->pred
->pred_next
!= NULL
)
2684 /* THEN must do something. */
2685 if (forwarder_block_p (then_bb
))
2688 num_possible_if_blocks
++;
2690 fprintf (rtl_dump_file
,
2691 "\nIF-CASE-1 found, start %d, then %d\n",
2692 test_bb
->index
, then_bb
->index
);
2694 /* THEN is small. */
2695 if (count_bb_insns (then_bb
) > BRANCH_COST
)
2698 /* Registers set are dead, or are predicable. */
2699 if (! dead_or_predicable (test_bb
, then_bb
, else_bb
,
2700 then_bb
->succ
->dest
, 1))
2703 /* Conversion went ok, including moving the insns and fixing up the
2704 jump. Adjust the CFG to match. */
2706 bitmap_operation (test_bb
->global_live_at_end
,
2707 else_bb
->global_live_at_start
,
2708 then_bb
->global_live_at_end
, BITMAP_IOR
);
2710 new_bb
= redirect_edge_and_branch_force (FALLTHRU_EDGE (test_bb
), else_bb
);
2711 then_bb_index
= then_bb
->index
;
2712 if (post_dominators
)
2713 delete_from_dominance_info (post_dominators
, then_bb
);
2714 flow_delete_block (then_bb
);
2716 /* Make rest of code believe that the newly created block is the THEN_BB
2717 block we removed. */
2720 new_bb
->index
= then_bb_index
;
2721 BASIC_BLOCK (then_bb_index
) = new_bb
;
2723 /* We've possibly created jump to next insn, cleanup_cfg will solve that
2726 num_removed_blocks
++;
2727 num_updated_if_blocks
++;
2732 /* Test for case 2 above. */
2735 find_if_case_2 (test_bb
, then_edge
, else_edge
)
2736 basic_block test_bb
;
2737 edge then_edge
, else_edge
;
2739 basic_block then_bb
= then_edge
->dest
;
2740 basic_block else_bb
= else_edge
->dest
;
2741 edge else_succ
= else_bb
->succ
;
2744 /* ELSE has one successor. */
2745 if (!else_succ
|| else_succ
->succ_next
!= NULL
)
2748 /* ELSE outgoing edge is not complex. */
2749 if (else_succ
->flags
& EDGE_COMPLEX
)
2752 /* ELSE has one predecessor. */
2753 if (else_bb
->pred
->pred_next
!= NULL
)
2756 /* THEN is not EXIT. */
2757 if (then_bb
->index
< 0)
2760 /* ELSE is predicted or SUCC(ELSE) postdominates THEN. */
2761 note
= find_reg_note (test_bb
->end
, REG_BR_PROB
, NULL_RTX
);
2762 if (note
&& INTVAL (XEXP (note
, 0)) >= REG_BR_PROB_BASE
/ 2)
2764 else if (else_succ
->dest
->index
< 0
2765 || dominated_by_p (post_dominators
, then_bb
,
2771 num_possible_if_blocks
++;
2773 fprintf (rtl_dump_file
,
2774 "\nIF-CASE-2 found, start %d, else %d\n",
2775 test_bb
->index
, else_bb
->index
);
2777 /* ELSE is small. */
2778 if (count_bb_insns (then_bb
) > BRANCH_COST
)
2781 /* Registers set are dead, or are predicable. */
2782 if (! dead_or_predicable (test_bb
, else_bb
, then_bb
, else_succ
->dest
, 0))
2785 /* Conversion went ok, including moving the insns and fixing up the
2786 jump. Adjust the CFG to match. */
2788 bitmap_operation (test_bb
->global_live_at_end
,
2789 then_bb
->global_live_at_start
,
2790 else_bb
->global_live_at_end
, BITMAP_IOR
);
2792 if (post_dominators
)
2793 delete_from_dominance_info (post_dominators
, else_bb
);
2794 flow_delete_block (else_bb
);
2796 num_removed_blocks
++;
2797 num_updated_if_blocks
++;
2799 /* ??? We may now fallthru from one of THEN's successors into a join
2800 block. Rerun cleanup_cfg? Examine things manually? Wait? */
2805 /* A subroutine of dead_or_predicable called through for_each_rtx.
2806 Return 1 if a memory is found. */
2809 find_memory (px
, data
)
2811 void *data ATTRIBUTE_UNUSED
;
2813 return GET_CODE (*px
) == MEM
;
2816 /* Used by the code above to perform the actual rtl transformations.
2817 Return TRUE if successful.
2819 TEST_BB is the block containing the conditional branch. MERGE_BB
2820 is the block containing the code to manipulate. NEW_DEST is the
2821 label TEST_BB should be branching to after the conversion.
2822 REVERSEP is true if the sense of the branch should be reversed. */
2825 dead_or_predicable (test_bb
, merge_bb
, other_bb
, new_dest
, reversep
)
2826 basic_block test_bb
, merge_bb
, other_bb
;
2827 basic_block new_dest
;
2830 rtx head
, end
, jump
, earliest
, old_dest
, new_label
= NULL_RTX
;
2832 jump
= test_bb
->end
;
2834 /* Find the extent of the real code in the merge block. */
2835 head
= merge_bb
->head
;
2836 end
= merge_bb
->end
;
2838 if (GET_CODE (head
) == CODE_LABEL
)
2839 head
= NEXT_INSN (head
);
2840 if (GET_CODE (head
) == NOTE
)
2844 head
= end
= NULL_RTX
;
2847 head
= NEXT_INSN (head
);
2850 if (GET_CODE (end
) == JUMP_INSN
)
2854 head
= end
= NULL_RTX
;
2857 end
= PREV_INSN (end
);
2860 /* Disable handling dead code by conditional execution if the machine needs
2861 to do anything funny with the tests, etc. */
2862 #ifndef IFCVT_MODIFY_TESTS
2863 if (HAVE_conditional_execution
)
2865 /* In the conditional execution case, we have things easy. We know
2866 the condition is reversable. We don't have to check life info,
2867 becase we're going to conditionally execute the code anyway.
2868 All that's left is making sure the insns involved can actually
2873 cond
= cond_exec_get_condition (jump
);
2877 prob_val
= find_reg_note (jump
, REG_BR_PROB
, NULL_RTX
);
2879 prob_val
= XEXP (prob_val
, 0);
2883 enum rtx_code rev
= reversed_comparison_code (cond
, jump
);
2886 cond
= gen_rtx_fmt_ee (rev
, GET_MODE (cond
), XEXP (cond
, 0),
2889 prob_val
= GEN_INT (REG_BR_PROB_BASE
- INTVAL (prob_val
));
2892 if (! cond_exec_process_insns ((ce_if_block_t
*)0, head
, end
, cond
,
2901 /* In the non-conditional execution case, we have to verify that there
2902 are no trapping operations, no calls, no references to memory, and
2903 that any registers modified are dead at the branch site. */
2905 rtx insn
, cond
, prev
;
2906 regset_head merge_set_head
, tmp_head
, test_live_head
, test_set_head
;
2907 regset merge_set
, tmp
, test_live
, test_set
;
2908 struct propagate_block_info
*pbi
;
2911 /* Check for no calls or trapping operations. */
2912 for (insn
= head
; ; insn
= NEXT_INSN (insn
))
2914 if (GET_CODE (insn
) == CALL_INSN
)
2918 if (may_trap_p (PATTERN (insn
)))
2921 /* ??? Even non-trapping memories such as stack frame
2922 references must be avoided. For stores, we collect
2923 no lifetime info; for reads, we'd have to assert
2924 true_dependence false against every store in the
2926 if (for_each_rtx (&PATTERN (insn
), find_memory
, NULL
))
2933 if (! any_condjump_p (jump
))
2936 /* Find the extent of the conditional. */
2937 cond
= noce_get_condition (jump
, &earliest
);
2942 MERGE_SET = set of registers set in MERGE_BB
2943 TEST_LIVE = set of registers live at EARLIEST
2944 TEST_SET = set of registers set between EARLIEST and the
2945 end of the block. */
2947 tmp
= INITIALIZE_REG_SET (tmp_head
);
2948 merge_set
= INITIALIZE_REG_SET (merge_set_head
);
2949 test_live
= INITIALIZE_REG_SET (test_live_head
);
2950 test_set
= INITIALIZE_REG_SET (test_set_head
);
2952 /* ??? bb->local_set is only valid during calculate_global_regs_live,
2953 so we must recompute usage for MERGE_BB. Not so bad, I suppose,
2954 since we've already asserted that MERGE_BB is small. */
2955 propagate_block (merge_bb
, tmp
, merge_set
, merge_set
, 0);
2957 /* For small register class machines, don't lengthen lifetimes of
2958 hard registers before reload. */
2959 if (SMALL_REGISTER_CLASSES
&& ! reload_completed
)
2961 EXECUTE_IF_SET_IN_BITMAP
2964 if (i
< FIRST_PSEUDO_REGISTER
2966 && ! global_regs
[i
])
2971 /* For TEST, we're interested in a range of insns, not a whole block.
2972 Moreover, we're interested in the insns live from OTHER_BB. */
2974 COPY_REG_SET (test_live
, other_bb
->global_live_at_start
);
2975 pbi
= init_propagate_block_info (test_bb
, test_live
, test_set
, test_set
,
2978 for (insn
= jump
; ; insn
= prev
)
2980 prev
= propagate_one_insn (pbi
, insn
);
2981 if (insn
== earliest
)
2985 free_propagate_block_info (pbi
);
2987 /* We can perform the transformation if
2988 MERGE_SET & (TEST_SET | TEST_LIVE)
2990 TEST_SET & merge_bb->global_live_at_start
2993 bitmap_operation (tmp
, test_set
, test_live
, BITMAP_IOR
);
2994 bitmap_operation (tmp
, tmp
, merge_set
, BITMAP_AND
);
2995 EXECUTE_IF_SET_IN_BITMAP(tmp
, 0, i
, fail
= 1);
2997 bitmap_operation (tmp
, test_set
, merge_bb
->global_live_at_start
,
2999 EXECUTE_IF_SET_IN_BITMAP(tmp
, 0, i
, fail
= 1);
3002 FREE_REG_SET (merge_set
);
3003 FREE_REG_SET (test_live
);
3004 FREE_REG_SET (test_set
);
3011 /* We don't want to use normal invert_jump or redirect_jump because
3012 we don't want to delete_insn called. Also, we want to do our own
3013 change group management. */
3015 old_dest
= JUMP_LABEL (jump
);
3016 if (other_bb
!= new_dest
)
3018 new_label
= block_label (new_dest
);
3020 ? ! invert_jump_1 (jump
, new_label
)
3021 : ! redirect_jump_1 (jump
, new_label
))
3025 if (! apply_change_group ())
3028 if (other_bb
!= new_dest
)
3031 LABEL_NUSES (old_dest
) -= 1;
3033 LABEL_NUSES (new_label
) += 1;
3034 JUMP_LABEL (jump
) = new_label
;
3036 invert_br_probabilities (jump
);
3038 redirect_edge_succ (BRANCH_EDGE (test_bb
), new_dest
);
3041 gcov_type count
, probability
;
3042 count
= BRANCH_EDGE (test_bb
)->count
;
3043 BRANCH_EDGE (test_bb
)->count
= FALLTHRU_EDGE (test_bb
)->count
;
3044 FALLTHRU_EDGE (test_bb
)->count
= count
;
3045 probability
= BRANCH_EDGE (test_bb
)->probability
;
3046 BRANCH_EDGE (test_bb
)->probability
3047 = FALLTHRU_EDGE (test_bb
)->probability
;
3048 FALLTHRU_EDGE (test_bb
)->probability
= probability
;
3049 update_br_prob_note (test_bb
);
3053 /* Move the insns out of MERGE_BB to before the branch. */
3056 if (end
== merge_bb
->end
)
3057 merge_bb
->end
= PREV_INSN (head
);
3059 if (squeeze_notes (&head
, &end
))
3062 reorder_insns (head
, end
, PREV_INSN (earliest
));
3065 /* Remove the jump and edge if we can. */
3066 if (other_bb
== new_dest
)
3069 remove_edge (BRANCH_EDGE (test_bb
));
3070 /* ??? Can't merge blocks here, as then_bb is still in use.
3071 At minimum, the merge will get done just before bb-reorder. */
3081 /* Main entry point for all if-conversion. */
3084 if_convert (x_life_data_ok
)
3090 num_possible_if_blocks
= 0;
3091 num_updated_if_blocks
= 0;
3092 num_removed_blocks
= 0;
3093 life_data_ok
= (x_life_data_ok
!= 0);
3095 /* Free up basic_block_for_insn so that we don't have to keep it
3096 up to date, either here or in merge_blocks_nomove. */
3097 free_basic_block_vars (1);
3099 /* Compute postdominators if we think we'll use them. */
3100 post_dominators
= NULL
;
3101 if (HAVE_conditional_execution
|| life_data_ok
)
3103 post_dominators
= calculate_dominance_info (CDI_POST_DOMINATORS
);
3108 /* Go through each of the basic blocks looking for things to convert. If we
3109 have conditional execution, we make multiple passes to allow us to handle
3110 IF-THEN{-ELSE} blocks within other IF-THEN{-ELSE} blocks. */
3114 cond_exec_changed_p
= FALSE
;
3117 #ifdef IFCVT_MULTIPLE_DUMPS
3118 if (rtl_dump_file
&& pass
> 1)
3119 fprintf (rtl_dump_file
, "\n\n========== Pass %d ==========\n", pass
);
3124 basic_block new_bb
= find_if_header (bb
, pass
);
3129 #ifdef IFCVT_MULTIPLE_DUMPS
3130 if (rtl_dump_file
&& cond_exec_changed_p
)
3131 print_rtl_with_bb (rtl_dump_file
, get_insns ());
3134 while (cond_exec_changed_p
);
3136 #ifdef IFCVT_MULTIPLE_DUMPS
3138 fprintf (rtl_dump_file
, "\n\n========== no more changes\n");
3141 if (post_dominators
)
3142 free_dominance_info (post_dominators
);
3145 fflush (rtl_dump_file
);
3147 clear_aux_for_blocks ();
3149 /* Rebuild life info for basic blocks that require it. */
3150 if (num_removed_blocks
&& life_data_ok
)
3152 /* If we allocated new pseudos, we must resize the array for sched1. */
3153 if (max_regno
< max_reg_num ())
3155 max_regno
= max_reg_num ();
3156 allocate_reg_info (max_regno
, FALSE
, FALSE
);
3158 update_life_info_in_dirty_blocks (UPDATE_LIFE_GLOBAL_RM_NOTES
,
3159 PROP_DEATH_NOTES
| PROP_SCAN_DEAD_CODE
3160 | PROP_KILL_DEAD_CODE
);
3163 /* Write the final stats. */
3164 if (rtl_dump_file
&& num_possible_if_blocks
> 0)
3166 fprintf (rtl_dump_file
,
3167 "\n%d possible IF blocks searched.\n",
3168 num_possible_if_blocks
);
3169 fprintf (rtl_dump_file
,
3170 "%d IF blocks converted.\n",
3171 num_updated_if_blocks
);
3172 fprintf (rtl_dump_file
,
3173 "%d basic blocks deleted.\n\n\n",
3174 num_removed_blocks
);
3177 #ifdef ENABLE_CHECKING
3178 verify_flow_info ();