1 /* If-conversion support.
2 Copyright (C) 2000, 2001, 2002, 2003, 2004 Free Software Foundation, Inc.
4 This file is part of GCC.
6 GCC is free software; you can redistribute it and/or modify it
7 under the terms of the GNU General Public License as published by
8 the Free Software Foundation; either version 2, or (at your option)
11 GCC is distributed in the hope that it will be useful, but WITHOUT
12 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
13 or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public
14 License for more details.
16 You should have received a copy of the GNU General Public License
17 along with GCC; see the file COPYING. If not, write to the Free
18 Software Foundation, 59 Temple Place - Suite 330, Boston, MA
23 #include "coretypes.h"
30 #include "insn-config.h"
33 #include "hard-reg-set.h"
34 #include "basic-block.h"
45 #ifndef HAVE_conditional_execution
46 #define HAVE_conditional_execution 0
48 #ifndef HAVE_conditional_move
49 #define HAVE_conditional_move 0
60 #ifndef HAVE_conditional_trap
61 #define HAVE_conditional_trap 0
64 #ifndef MAX_CONDITIONAL_EXECUTE
65 #define MAX_CONDITIONAL_EXECUTE (BRANCH_COST + 1)
68 #define NULL_EDGE ((struct edge_def *)NULL)
69 #define NULL_BLOCK ((struct basic_block_def *)NULL)
71 /* # of IF-THEN or IF-THEN-ELSE blocks we looked at */
72 static int num_possible_if_blocks
;
74 /* # of IF-THEN or IF-THEN-ELSE blocks were converted to conditional
76 static int num_updated_if_blocks
;
78 /* # of changes made which require life information to be updated. */
79 static int num_true_changes
;
81 /* Whether conditional execution changes were made. */
82 static int cond_exec_changed_p
;
84 /* True if life data ok at present. */
85 static bool life_data_ok
;
87 /* Forward references. */
88 static int count_bb_insns (basic_block
);
89 static int total_bb_rtx_cost (basic_block
);
90 static rtx
first_active_insn (basic_block
);
91 static rtx
last_active_insn (basic_block
, int);
92 static basic_block
block_fallthru (basic_block
);
93 static int cond_exec_process_insns (ce_if_block_t
*, rtx
, rtx
, rtx
, rtx
, int);
94 static rtx
cond_exec_get_condition (rtx
);
95 static int cond_exec_process_if_block (ce_if_block_t
*, int);
96 static rtx
noce_get_condition (rtx
, rtx
*);
97 static int noce_operand_ok (rtx
);
98 static int noce_process_if_block (ce_if_block_t
*);
99 static int process_if_block (ce_if_block_t
*);
100 static void merge_if_block (ce_if_block_t
*);
101 static int find_cond_trap (basic_block
, edge
, edge
);
102 static basic_block
find_if_header (basic_block
, int);
103 static int block_jumps_and_fallthru_p (basic_block
, basic_block
);
104 static int find_if_block (ce_if_block_t
*);
105 static int find_if_case_1 (basic_block
, edge
, edge
);
106 static int find_if_case_2 (basic_block
, edge
, edge
);
107 static int find_memory (rtx
*, void *);
108 static int dead_or_predicable (basic_block
, basic_block
, basic_block
,
110 static void noce_emit_move_insn (rtx
, rtx
);
111 static rtx
block_has_only_trap (basic_block
);
112 static void mark_loop_exit_edges (void);
114 /* Sets EDGE_LOOP_EXIT flag for all loop exits. */
116 mark_loop_exit_edges (void)
122 flow_loops_find (&loops
, LOOP_TREE
);
123 free_dominance_info (CDI_DOMINATORS
);
129 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
131 if (find_common_loop (bb
->loop_father
, e
->dest
->loop_father
)
133 e
->flags
|= EDGE_LOOP_EXIT
;
135 e
->flags
&= ~EDGE_LOOP_EXIT
;
140 flow_loops_free (&loops
);
143 /* Count the number of non-jump active insns in BB. */
146 count_bb_insns (basic_block bb
)
149 rtx insn
= BB_HEAD (bb
);
153 if (CALL_P (insn
) || NONJUMP_INSN_P (insn
))
156 if (insn
== BB_END (bb
))
158 insn
= NEXT_INSN (insn
);
164 /* Count the total rtx_cost of non-jump active insns in BB. */
167 total_bb_rtx_cost (basic_block bb
)
170 rtx insn
= BB_HEAD (bb
);
174 if (GET_CODE (insn
) == CALL_INSN
|| GET_CODE (insn
) == INSN
)
175 count
+= rtx_cost (PATTERN (insn
), 0);
177 if (insn
== BB_END (bb
))
179 insn
= NEXT_INSN (insn
);
185 /* Return the first non-jump active insn in the basic block. */
188 first_active_insn (basic_block bb
)
190 rtx insn
= BB_HEAD (bb
);
194 if (insn
== BB_END (bb
))
196 insn
= NEXT_INSN (insn
);
199 while (NOTE_P (insn
))
201 if (insn
== BB_END (bb
))
203 insn
= NEXT_INSN (insn
);
212 /* Return the last non-jump active (non-jump) insn in the basic block. */
215 last_active_insn (basic_block bb
, int skip_use_p
)
217 rtx insn
= BB_END (bb
);
218 rtx head
= BB_HEAD (bb
);
223 && NONJUMP_INSN_P (insn
)
224 && GET_CODE (PATTERN (insn
)) == USE
))
228 insn
= PREV_INSN (insn
);
237 /* Return the basic block reached by falling though the basic block BB. */
240 block_fallthru (basic_block bb
)
245 e
!= NULL_EDGE
&& (e
->flags
& EDGE_FALLTHRU
) == 0;
249 return (e
) ? e
->dest
: NULL_BLOCK
;
252 /* Go through a bunch of insns, converting them to conditional
253 execution format if possible. Return TRUE if all of the non-note
254 insns were processed. */
257 cond_exec_process_insns (ce_if_block_t
*ce_info ATTRIBUTE_UNUSED
,
258 /* if block information */rtx start
,
259 /* first insn to look at */rtx end
,
260 /* last insn to look at */rtx test
,
261 /* conditional execution test */rtx prob_val
,
262 /* probability of branch taken. */int mod_ok
)
264 int must_be_last
= FALSE
;
272 for (insn
= start
; ; insn
= NEXT_INSN (insn
))
277 if (!NONJUMP_INSN_P (insn
) && !CALL_P (insn
))
280 /* Remove USE insns that get in the way. */
281 if (reload_completed
&& GET_CODE (PATTERN (insn
)) == USE
)
283 /* ??? Ug. Actually unlinking the thing is problematic,
284 given what we'd have to coordinate with our callers. */
285 SET_INSN_DELETED (insn
);
289 /* Last insn wasn't last? */
293 if (modified_in_p (test
, insn
))
300 /* Now build the conditional form of the instruction. */
301 pattern
= PATTERN (insn
);
302 xtest
= copy_rtx (test
);
304 /* If this is already a COND_EXEC, rewrite the test to be an AND of the
306 if (GET_CODE (pattern
) == COND_EXEC
)
308 if (GET_MODE (xtest
) != GET_MODE (COND_EXEC_TEST (pattern
)))
311 xtest
= gen_rtx_AND (GET_MODE (xtest
), xtest
,
312 COND_EXEC_TEST (pattern
));
313 pattern
= COND_EXEC_CODE (pattern
);
316 pattern
= gen_rtx_COND_EXEC (VOIDmode
, xtest
, pattern
);
318 /* If the machine needs to modify the insn being conditionally executed,
319 say for example to force a constant integer operand into a temp
320 register, do so here. */
321 #ifdef IFCVT_MODIFY_INSN
322 IFCVT_MODIFY_INSN (ce_info
, pattern
, insn
);
327 validate_change (insn
, &PATTERN (insn
), pattern
, 1);
329 if (CALL_P (insn
) && prob_val
)
330 validate_change (insn
, ®_NOTES (insn
),
331 alloc_EXPR_LIST (REG_BR_PROB
, prob_val
,
332 REG_NOTES (insn
)), 1);
342 /* Return the condition for a jump. Do not do any special processing. */
345 cond_exec_get_condition (rtx jump
)
349 if (any_condjump_p (jump
))
350 test_if
= SET_SRC (pc_set (jump
));
353 cond
= XEXP (test_if
, 0);
355 /* If this branches to JUMP_LABEL when the condition is false,
356 reverse the condition. */
357 if (GET_CODE (XEXP (test_if
, 2)) == LABEL_REF
358 && XEXP (XEXP (test_if
, 2), 0) == JUMP_LABEL (jump
))
360 enum rtx_code rev
= reversed_comparison_code (cond
, jump
);
364 cond
= gen_rtx_fmt_ee (rev
, GET_MODE (cond
), XEXP (cond
, 0),
371 /* Given a simple IF-THEN or IF-THEN-ELSE block, attempt to convert it
372 to conditional execution. Return TRUE if we were successful at
373 converting the block. */
376 cond_exec_process_if_block (ce_if_block_t
* ce_info
,
377 /* if block information */int do_multiple_p
)
379 basic_block test_bb
= ce_info
->test_bb
; /* last test block */
380 basic_block then_bb
= ce_info
->then_bb
; /* THEN */
381 basic_block else_bb
= ce_info
->else_bb
; /* ELSE or NULL */
382 rtx test_expr
; /* expression in IF_THEN_ELSE that is tested */
383 rtx then_start
; /* first insn in THEN block */
384 rtx then_end
; /* last insn + 1 in THEN block */
385 rtx else_start
= NULL_RTX
; /* first insn in ELSE block or NULL */
386 rtx else_end
= NULL_RTX
; /* last insn + 1 in ELSE block */
387 int max
; /* max # of insns to convert. */
388 int then_mod_ok
; /* whether conditional mods are ok in THEN */
389 rtx true_expr
; /* test for else block insns */
390 rtx false_expr
; /* test for then block insns */
391 rtx true_prob_val
; /* probability of else block */
392 rtx false_prob_val
; /* probability of then block */
394 enum rtx_code false_code
;
396 /* If test is comprised of && or || elements, and we've failed at handling
397 all of them together, just use the last test if it is the special case of
398 && elements without an ELSE block. */
399 if (!do_multiple_p
&& ce_info
->num_multiple_test_blocks
)
401 if (else_bb
|| ! ce_info
->and_and_p
)
404 ce_info
->test_bb
= test_bb
= ce_info
->last_test_bb
;
405 ce_info
->num_multiple_test_blocks
= 0;
406 ce_info
->num_and_and_blocks
= 0;
407 ce_info
->num_or_or_blocks
= 0;
410 /* Find the conditional jump to the ELSE or JOIN part, and isolate
412 test_expr
= cond_exec_get_condition (BB_END (test_bb
));
416 /* If the conditional jump is more than just a conditional jump,
417 then we can not do conditional execution conversion on this block. */
418 if (! onlyjump_p (BB_END (test_bb
)))
421 /* Collect the bounds of where we're to search, skipping any labels, jumps
422 and notes at the beginning and end of the block. Then count the total
423 number of insns and see if it is small enough to convert. */
424 then_start
= first_active_insn (then_bb
);
425 then_end
= last_active_insn (then_bb
, TRUE
);
426 n_insns
= ce_info
->num_then_insns
= count_bb_insns (then_bb
);
427 max
= MAX_CONDITIONAL_EXECUTE
;
432 else_start
= first_active_insn (else_bb
);
433 else_end
= last_active_insn (else_bb
, TRUE
);
434 n_insns
+= ce_info
->num_else_insns
= count_bb_insns (else_bb
);
440 /* Map test_expr/test_jump into the appropriate MD tests to use on
441 the conditionally executed code. */
443 true_expr
= test_expr
;
445 false_code
= reversed_comparison_code (true_expr
, BB_END (test_bb
));
446 if (false_code
!= UNKNOWN
)
447 false_expr
= gen_rtx_fmt_ee (false_code
, GET_MODE (true_expr
),
448 XEXP (true_expr
, 0), XEXP (true_expr
, 1));
450 false_expr
= NULL_RTX
;
452 #ifdef IFCVT_MODIFY_TESTS
453 /* If the machine description needs to modify the tests, such as setting a
454 conditional execution register from a comparison, it can do so here. */
455 IFCVT_MODIFY_TESTS (ce_info
, true_expr
, false_expr
);
457 /* See if the conversion failed. */
458 if (!true_expr
|| !false_expr
)
462 true_prob_val
= find_reg_note (BB_END (test_bb
), REG_BR_PROB
, NULL_RTX
);
465 true_prob_val
= XEXP (true_prob_val
, 0);
466 false_prob_val
= GEN_INT (REG_BR_PROB_BASE
- INTVAL (true_prob_val
));
469 false_prob_val
= NULL_RTX
;
471 /* If we have && or || tests, do them here. These tests are in the adjacent
472 blocks after the first block containing the test. */
473 if (ce_info
->num_multiple_test_blocks
> 0)
475 basic_block bb
= test_bb
;
476 basic_block last_test_bb
= ce_info
->last_test_bb
;
486 bb
= block_fallthru (bb
);
487 start
= first_active_insn (bb
);
488 end
= last_active_insn (bb
, TRUE
);
490 && ! cond_exec_process_insns (ce_info
, start
, end
, false_expr
,
491 false_prob_val
, FALSE
))
494 /* If the conditional jump is more than just a conditional jump, then
495 we can not do conditional execution conversion on this block. */
496 if (! onlyjump_p (BB_END (bb
)))
499 /* Find the conditional jump and isolate the test. */
500 t
= cond_exec_get_condition (BB_END (bb
));
504 f
= gen_rtx_fmt_ee (reverse_condition (GET_CODE (t
)),
509 if (ce_info
->and_and_p
)
511 t
= gen_rtx_AND (GET_MODE (t
), true_expr
, t
);
512 f
= gen_rtx_IOR (GET_MODE (t
), false_expr
, f
);
516 t
= gen_rtx_IOR (GET_MODE (t
), true_expr
, t
);
517 f
= gen_rtx_AND (GET_MODE (t
), false_expr
, f
);
520 /* If the machine description needs to modify the tests, such as
521 setting a conditional execution register from a comparison, it can
523 #ifdef IFCVT_MODIFY_MULTIPLE_TESTS
524 IFCVT_MODIFY_MULTIPLE_TESTS (ce_info
, bb
, t
, f
);
526 /* See if the conversion failed. */
534 while (bb
!= last_test_bb
);
537 /* For IF-THEN-ELSE blocks, we don't allow modifications of the test
538 on then THEN block. */
539 then_mod_ok
= (else_bb
== NULL_BLOCK
);
541 /* Go through the THEN and ELSE blocks converting the insns if possible
542 to conditional execution. */
546 || ! cond_exec_process_insns (ce_info
, then_start
, then_end
,
547 false_expr
, false_prob_val
,
551 if (else_bb
&& else_end
552 && ! cond_exec_process_insns (ce_info
, else_start
, else_end
,
553 true_expr
, true_prob_val
, TRUE
))
556 /* If we cannot apply the changes, fail. Do not go through the normal fail
557 processing, since apply_change_group will call cancel_changes. */
558 if (! apply_change_group ())
560 #ifdef IFCVT_MODIFY_CANCEL
561 /* Cancel any machine dependent changes. */
562 IFCVT_MODIFY_CANCEL (ce_info
);
567 #ifdef IFCVT_MODIFY_FINAL
568 /* Do any machine dependent final modifications. */
569 IFCVT_MODIFY_FINAL (ce_info
);
572 /* Conversion succeeded. */
574 fprintf (dump_file
, "%d insn%s converted to conditional execution.\n",
575 n_insns
, (n_insns
== 1) ? " was" : "s were");
577 /* Merge the blocks! */
578 merge_if_block (ce_info
);
579 cond_exec_changed_p
= TRUE
;
583 #ifdef IFCVT_MODIFY_CANCEL
584 /* Cancel any machine dependent changes. */
585 IFCVT_MODIFY_CANCEL (ce_info
);
592 /* Used by noce_process_if_block to communicate with its subroutines.
594 The subroutines know that A and B may be evaluated freely. They
595 know that X is a register. They should insert new instructions
596 before cond_earliest. */
603 rtx jump
, cond
, cond_earliest
;
604 /* True if "b" was originally evaluated unconditionally. */
605 bool b_unconditional
;
608 static rtx
noce_emit_store_flag (struct noce_if_info
*, rtx
, int, int);
609 static int noce_try_move (struct noce_if_info
*);
610 static int noce_try_store_flag (struct noce_if_info
*);
611 static int noce_try_addcc (struct noce_if_info
*);
612 static int noce_try_store_flag_constants (struct noce_if_info
*);
613 static int noce_try_store_flag_mask (struct noce_if_info
*);
614 static rtx
noce_emit_cmove (struct noce_if_info
*, rtx
, enum rtx_code
, rtx
,
616 static int noce_try_cmove (struct noce_if_info
*);
617 static int noce_try_cmove_arith (struct noce_if_info
*);
618 static rtx
noce_get_alt_condition (struct noce_if_info
*, rtx
, rtx
*);
619 static int noce_try_minmax (struct noce_if_info
*);
620 static int noce_try_abs (struct noce_if_info
*);
621 static int noce_try_sign_mask (struct noce_if_info
*);
623 /* Helper function for noce_try_store_flag*. */
626 noce_emit_store_flag (struct noce_if_info
*if_info
, rtx x
, int reversep
,
629 rtx cond
= if_info
->cond
;
633 cond_complex
= (! general_operand (XEXP (cond
, 0), VOIDmode
)
634 || ! general_operand (XEXP (cond
, 1), VOIDmode
));
636 /* If earliest == jump, or when the condition is complex, try to
637 build the store_flag insn directly. */
640 cond
= XEXP (SET_SRC (pc_set (if_info
->jump
)), 0);
643 code
= reversed_comparison_code (cond
, if_info
->jump
);
645 code
= GET_CODE (cond
);
647 if ((if_info
->cond_earliest
== if_info
->jump
|| cond_complex
)
648 && (normalize
== 0 || STORE_FLAG_VALUE
== normalize
))
652 tmp
= gen_rtx_fmt_ee (code
, GET_MODE (x
), XEXP (cond
, 0),
654 tmp
= gen_rtx_SET (VOIDmode
, x
, tmp
);
657 tmp
= emit_insn (tmp
);
659 if (recog_memoized (tmp
) >= 0)
665 if_info
->cond_earliest
= if_info
->jump
;
673 /* Don't even try if the comparison operands or the mode of X are weird. */
674 if (cond_complex
|| !SCALAR_INT_MODE_P (GET_MODE (x
)))
677 return emit_store_flag (x
, code
, XEXP (cond
, 0),
678 XEXP (cond
, 1), VOIDmode
,
679 (code
== LTU
|| code
== LEU
680 || code
== GEU
|| code
== GTU
), normalize
);
683 /* Emit instruction to move an rtx, possibly into STRICT_LOW_PART.
684 X is the destination/target and Y is the value to copy. */
687 noce_emit_move_insn (rtx x
, rtx y
)
689 enum machine_mode outmode
, inmode
;
693 if (GET_CODE (x
) != STRICT_LOW_PART
)
695 emit_move_insn (x
, y
);
700 inner
= XEXP (outer
, 0);
701 outmode
= GET_MODE (outer
);
702 inmode
= GET_MODE (inner
);
703 bitpos
= SUBREG_BYTE (outer
) * BITS_PER_UNIT
;
704 store_bit_field (inner
, GET_MODE_BITSIZE (outmode
), bitpos
, outmode
, y
,
705 GET_MODE_BITSIZE (inmode
));
708 /* Return sequence of instructions generated by if conversion. This
709 function calls end_sequence() to end the current stream, ensures
710 that are instructions are unshared, recognizable non-jump insns.
711 On failure, this function returns a NULL_RTX. */
714 end_ifcvt_sequence (struct noce_if_info
*if_info
)
717 rtx seq
= get_insns ();
719 set_used_flags (if_info
->x
);
720 set_used_flags (if_info
->cond
);
721 unshare_all_rtl_in_chain (seq
);
724 /* Make sure that all of the instructions emitted are recognizable,
725 and that we haven't introduced a new jump instruction.
726 As an exercise for the reader, build a general mechanism that
727 allows proper placement of required clobbers. */
728 for (insn
= seq
; insn
; insn
= NEXT_INSN (insn
))
730 || recog_memoized (insn
) == -1)
736 /* Convert "if (a != b) x = a; else x = b" into "x = a" and
737 "if (a == b) x = a; else x = b" into "x = b". */
740 noce_try_move (struct noce_if_info
*if_info
)
742 rtx cond
= if_info
->cond
;
743 enum rtx_code code
= GET_CODE (cond
);
746 if (code
!= NE
&& code
!= EQ
)
749 /* This optimization isn't valid if either A or B could be a NaN
751 if (HONOR_NANS (GET_MODE (if_info
->x
))
752 || HONOR_SIGNED_ZEROS (GET_MODE (if_info
->x
)))
755 /* Check whether the operands of the comparison are A and in
757 if ((rtx_equal_p (if_info
->a
, XEXP (cond
, 0))
758 && rtx_equal_p (if_info
->b
, XEXP (cond
, 1)))
759 || (rtx_equal_p (if_info
->a
, XEXP (cond
, 1))
760 && rtx_equal_p (if_info
->b
, XEXP (cond
, 0))))
762 y
= (code
== EQ
) ? if_info
->a
: if_info
->b
;
764 /* Avoid generating the move if the source is the destination. */
765 if (! rtx_equal_p (if_info
->x
, y
))
768 noce_emit_move_insn (if_info
->x
, y
);
769 seq
= end_ifcvt_sequence (if_info
);
773 emit_insn_before_setloc (seq
, if_info
->jump
,
774 INSN_LOCATOR (if_info
->insn_a
));
781 /* Convert "if (test) x = 1; else x = 0".
783 Only try 0 and STORE_FLAG_VALUE here. Other combinations will be
784 tried in noce_try_store_flag_constants after noce_try_cmove has had
785 a go at the conversion. */
788 noce_try_store_flag (struct noce_if_info
*if_info
)
793 if (GET_CODE (if_info
->b
) == CONST_INT
794 && INTVAL (if_info
->b
) == STORE_FLAG_VALUE
795 && if_info
->a
== const0_rtx
)
797 else if (if_info
->b
== const0_rtx
798 && GET_CODE (if_info
->a
) == CONST_INT
799 && INTVAL (if_info
->a
) == STORE_FLAG_VALUE
800 && (reversed_comparison_code (if_info
->cond
, if_info
->jump
)
808 target
= noce_emit_store_flag (if_info
, if_info
->x
, reversep
, 0);
811 if (target
!= if_info
->x
)
812 noce_emit_move_insn (if_info
->x
, target
);
814 seq
= end_ifcvt_sequence (if_info
);
818 emit_insn_before_setloc (seq
, if_info
->jump
,
819 INSN_LOCATOR (if_info
->insn_a
));
829 /* Convert "if (test) x = a; else x = b", for A and B constant. */
832 noce_try_store_flag_constants (struct noce_if_info
*if_info
)
836 HOST_WIDE_INT itrue
, ifalse
, diff
, tmp
;
837 int normalize
, can_reverse
;
838 enum machine_mode mode
;
841 && GET_CODE (if_info
->a
) == CONST_INT
842 && GET_CODE (if_info
->b
) == CONST_INT
)
844 mode
= GET_MODE (if_info
->x
);
845 ifalse
= INTVAL (if_info
->a
);
846 itrue
= INTVAL (if_info
->b
);
848 /* Make sure we can represent the difference between the two values. */
849 if ((itrue
- ifalse
> 0)
850 != ((ifalse
< 0) != (itrue
< 0) ? ifalse
< 0 : ifalse
< itrue
))
853 diff
= trunc_int_for_mode (itrue
- ifalse
, mode
);
855 can_reverse
= (reversed_comparison_code (if_info
->cond
, if_info
->jump
)
859 if (diff
== STORE_FLAG_VALUE
|| diff
== -STORE_FLAG_VALUE
)
861 else if (ifalse
== 0 && exact_log2 (itrue
) >= 0
862 && (STORE_FLAG_VALUE
== 1
863 || BRANCH_COST
>= 2))
865 else if (itrue
== 0 && exact_log2 (ifalse
) >= 0 && can_reverse
866 && (STORE_FLAG_VALUE
== 1 || BRANCH_COST
>= 2))
867 normalize
= 1, reversep
= 1;
869 && (STORE_FLAG_VALUE
== -1
870 || BRANCH_COST
>= 2))
872 else if (ifalse
== -1 && can_reverse
873 && (STORE_FLAG_VALUE
== -1 || BRANCH_COST
>= 2))
874 normalize
= -1, reversep
= 1;
875 else if ((BRANCH_COST
>= 2 && STORE_FLAG_VALUE
== -1)
883 tmp
= itrue
; itrue
= ifalse
; ifalse
= tmp
;
884 diff
= trunc_int_for_mode (-diff
, mode
);
888 target
= noce_emit_store_flag (if_info
, if_info
->x
, reversep
, normalize
);
895 /* if (test) x = 3; else x = 4;
896 => x = 3 + (test == 0); */
897 if (diff
== STORE_FLAG_VALUE
|| diff
== -STORE_FLAG_VALUE
)
899 target
= expand_simple_binop (mode
,
900 (diff
== STORE_FLAG_VALUE
902 GEN_INT (ifalse
), target
, if_info
->x
, 0,
906 /* if (test) x = 8; else x = 0;
907 => x = (test != 0) << 3; */
908 else if (ifalse
== 0 && (tmp
= exact_log2 (itrue
)) >= 0)
910 target
= expand_simple_binop (mode
, ASHIFT
,
911 target
, GEN_INT (tmp
), if_info
->x
, 0,
915 /* if (test) x = -1; else x = b;
916 => x = -(test != 0) | b; */
917 else if (itrue
== -1)
919 target
= expand_simple_binop (mode
, IOR
,
920 target
, GEN_INT (ifalse
), if_info
->x
, 0,
924 /* if (test) x = a; else x = b;
925 => x = (-(test != 0) & (b - a)) + a; */
928 target
= expand_simple_binop (mode
, AND
,
929 target
, GEN_INT (diff
), if_info
->x
, 0,
932 target
= expand_simple_binop (mode
, PLUS
,
933 target
, GEN_INT (ifalse
),
934 if_info
->x
, 0, OPTAB_WIDEN
);
943 if (target
!= if_info
->x
)
944 noce_emit_move_insn (if_info
->x
, target
);
946 seq
= end_ifcvt_sequence (if_info
);
950 emit_insn_before_setloc (seq
, if_info
->jump
,
951 INSN_LOCATOR (if_info
->insn_a
));
958 /* Convert "if (test) foo++" into "foo += (test != 0)", and
959 similarly for "foo--". */
962 noce_try_addcc (struct noce_if_info
*if_info
)
965 int subtract
, normalize
;
968 && GET_CODE (if_info
->a
) == PLUS
969 && rtx_equal_p (XEXP (if_info
->a
, 0), if_info
->b
)
970 && (reversed_comparison_code (if_info
->cond
, if_info
->jump
)
973 rtx cond
= if_info
->cond
;
974 enum rtx_code code
= reversed_comparison_code (cond
, if_info
->jump
);
976 /* First try to use addcc pattern. */
977 if (general_operand (XEXP (cond
, 0), VOIDmode
)
978 && general_operand (XEXP (cond
, 1), VOIDmode
))
981 target
= emit_conditional_add (if_info
->x
, code
,
986 XEXP (if_info
->a
, 1),
987 GET_MODE (if_info
->x
),
988 (code
== LTU
|| code
== GEU
989 || code
== LEU
|| code
== GTU
));
992 if (target
!= if_info
->x
)
993 noce_emit_move_insn (if_info
->x
, target
);
995 seq
= end_ifcvt_sequence (if_info
);
999 emit_insn_before_setloc (seq
, if_info
->jump
,
1000 INSN_LOCATOR (if_info
->insn_a
));
1006 /* If that fails, construct conditional increment or decrement using
1008 if (BRANCH_COST
>= 2
1009 && (XEXP (if_info
->a
, 1) == const1_rtx
1010 || XEXP (if_info
->a
, 1) == constm1_rtx
))
1013 if (STORE_FLAG_VALUE
== INTVAL (XEXP (if_info
->a
, 1)))
1014 subtract
= 0, normalize
= 0;
1015 else if (-STORE_FLAG_VALUE
== INTVAL (XEXP (if_info
->a
, 1)))
1016 subtract
= 1, normalize
= 0;
1018 subtract
= 0, normalize
= INTVAL (XEXP (if_info
->a
, 1));
1021 target
= noce_emit_store_flag (if_info
,
1022 gen_reg_rtx (GET_MODE (if_info
->x
)),
1026 target
= expand_simple_binop (GET_MODE (if_info
->x
),
1027 subtract
? MINUS
: PLUS
,
1028 if_info
->b
, target
, if_info
->x
,
1032 if (target
!= if_info
->x
)
1033 noce_emit_move_insn (if_info
->x
, target
);
1035 seq
= end_ifcvt_sequence (if_info
);
1039 emit_insn_before_setloc (seq
, if_info
->jump
,
1040 INSN_LOCATOR (if_info
->insn_a
));
1050 /* Convert "if (test) x = 0;" to "x &= -(test == 0);" */
1053 noce_try_store_flag_mask (struct noce_if_info
*if_info
)
1059 if (! no_new_pseudos
1060 && (BRANCH_COST
>= 2
1061 || STORE_FLAG_VALUE
== -1)
1062 && ((if_info
->a
== const0_rtx
1063 && rtx_equal_p (if_info
->b
, if_info
->x
))
1064 || ((reversep
= (reversed_comparison_code (if_info
->cond
,
1067 && if_info
->b
== const0_rtx
1068 && rtx_equal_p (if_info
->a
, if_info
->x
))))
1071 target
= noce_emit_store_flag (if_info
,
1072 gen_reg_rtx (GET_MODE (if_info
->x
)),
1075 target
= expand_simple_binop (GET_MODE (if_info
->x
), AND
,
1077 target
, if_info
->x
, 0,
1082 if (target
!= if_info
->x
)
1083 noce_emit_move_insn (if_info
->x
, target
);
1085 seq
= end_ifcvt_sequence (if_info
);
1089 emit_insn_before_setloc (seq
, if_info
->jump
,
1090 INSN_LOCATOR (if_info
->insn_a
));
1100 /* Helper function for noce_try_cmove and noce_try_cmove_arith. */
1103 noce_emit_cmove (struct noce_if_info
*if_info
, rtx x
, enum rtx_code code
,
1104 rtx cmp_a
, rtx cmp_b
, rtx vfalse
, rtx vtrue
)
1106 /* If earliest == jump, try to build the cmove insn directly.
1107 This is helpful when combine has created some complex condition
1108 (like for alpha's cmovlbs) that we can't hope to regenerate
1109 through the normal interface. */
1111 if (if_info
->cond_earliest
== if_info
->jump
)
1115 tmp
= gen_rtx_fmt_ee (code
, GET_MODE (if_info
->cond
), cmp_a
, cmp_b
);
1116 tmp
= gen_rtx_IF_THEN_ELSE (GET_MODE (x
), tmp
, vtrue
, vfalse
);
1117 tmp
= gen_rtx_SET (VOIDmode
, x
, tmp
);
1120 tmp
= emit_insn (tmp
);
1122 if (recog_memoized (tmp
) >= 0)
1134 /* Don't even try if the comparison operands are weird. */
1135 if (! general_operand (cmp_a
, GET_MODE (cmp_a
))
1136 || ! general_operand (cmp_b
, GET_MODE (cmp_b
)))
1139 #if HAVE_conditional_move
1140 return emit_conditional_move (x
, code
, cmp_a
, cmp_b
, VOIDmode
,
1141 vtrue
, vfalse
, GET_MODE (x
),
1142 (code
== LTU
|| code
== GEU
1143 || code
== LEU
|| code
== GTU
));
1145 /* We'll never get here, as noce_process_if_block doesn't call the
1146 functions involved. Ifdef code, however, should be discouraged
1147 because it leads to typos in the code not selected. However,
1148 emit_conditional_move won't exist either. */
1153 /* Try only simple constants and registers here. More complex cases
1154 are handled in noce_try_cmove_arith after noce_try_store_flag_arith
1155 has had a go at it. */
1158 noce_try_cmove (struct noce_if_info
*if_info
)
1163 if ((CONSTANT_P (if_info
->a
) || register_operand (if_info
->a
, VOIDmode
))
1164 && (CONSTANT_P (if_info
->b
) || register_operand (if_info
->b
, VOIDmode
)))
1168 code
= GET_CODE (if_info
->cond
);
1169 target
= noce_emit_cmove (if_info
, if_info
->x
, code
,
1170 XEXP (if_info
->cond
, 0),
1171 XEXP (if_info
->cond
, 1),
1172 if_info
->a
, if_info
->b
);
1176 if (target
!= if_info
->x
)
1177 noce_emit_move_insn (if_info
->x
, target
);
1179 seq
= end_ifcvt_sequence (if_info
);
1183 emit_insn_before_setloc (seq
, if_info
->jump
,
1184 INSN_LOCATOR (if_info
->insn_a
));
1197 /* Try more complex cases involving conditional_move. */
1200 noce_try_cmove_arith (struct noce_if_info
*if_info
)
1210 /* A conditional move from two memory sources is equivalent to a
1211 conditional on their addresses followed by a load. Don't do this
1212 early because it'll screw alias analysis. Note that we've
1213 already checked for no side effects. */
1214 if (! no_new_pseudos
&& cse_not_expected
1215 && MEM_P (a
) && MEM_P (b
)
1216 && BRANCH_COST
>= 5)
1220 x
= gen_reg_rtx (Pmode
);
1224 /* ??? We could handle this if we knew that a load from A or B could
1225 not fault. This is also true if we've already loaded
1226 from the address along the path from ENTRY. */
1227 else if (may_trap_p (a
) || may_trap_p (b
))
1230 /* if (test) x = a + b; else x = c - d;
1237 code
= GET_CODE (if_info
->cond
);
1238 insn_a
= if_info
->insn_a
;
1239 insn_b
= if_info
->insn_b
;
1241 /* Possibly rearrange operands to make things come out more natural. */
1242 if (reversed_comparison_code (if_info
->cond
, if_info
->jump
) != UNKNOWN
)
1245 if (rtx_equal_p (b
, x
))
1247 else if (general_operand (b
, GET_MODE (b
)))
1252 code
= reversed_comparison_code (if_info
->cond
, if_info
->jump
);
1253 tmp
= a
, a
= b
, b
= tmp
;
1254 tmp
= insn_a
, insn_a
= insn_b
, insn_b
= tmp
;
1260 /* If either operand is complex, load it into a register first.
1261 The best way to do this is to copy the original insn. In this
1262 way we preserve any clobbers etc that the insn may have had.
1263 This is of course not possible in the IS_MEM case. */
1264 if (! general_operand (a
, GET_MODE (a
)))
1269 goto end_seq_and_fail
;
1273 tmp
= gen_reg_rtx (GET_MODE (a
));
1274 tmp
= emit_insn (gen_rtx_SET (VOIDmode
, tmp
, a
));
1277 goto end_seq_and_fail
;
1280 a
= gen_reg_rtx (GET_MODE (a
));
1281 tmp
= copy_rtx (insn_a
);
1282 set
= single_set (tmp
);
1284 tmp
= emit_insn (PATTERN (tmp
));
1286 if (recog_memoized (tmp
) < 0)
1287 goto end_seq_and_fail
;
1289 if (! general_operand (b
, GET_MODE (b
)))
1294 goto end_seq_and_fail
;
1298 tmp
= gen_reg_rtx (GET_MODE (b
));
1299 tmp
= emit_insn (gen_rtx_SET (VOIDmode
,
1304 goto end_seq_and_fail
;
1307 b
= gen_reg_rtx (GET_MODE (b
));
1308 tmp
= copy_rtx (insn_b
);
1309 set
= single_set (tmp
);
1311 tmp
= emit_insn (PATTERN (tmp
));
1313 if (recog_memoized (tmp
) < 0)
1314 goto end_seq_and_fail
;
1317 target
= noce_emit_cmove (if_info
, x
, code
, XEXP (if_info
->cond
, 0),
1318 XEXP (if_info
->cond
, 1), a
, b
);
1321 goto end_seq_and_fail
;
1323 /* If we're handling a memory for above, emit the load now. */
1326 tmp
= gen_rtx_MEM (GET_MODE (if_info
->x
), target
);
1328 /* Copy over flags as appropriate. */
1329 if (MEM_VOLATILE_P (if_info
->a
) || MEM_VOLATILE_P (if_info
->b
))
1330 MEM_VOLATILE_P (tmp
) = 1;
1331 if (MEM_IN_STRUCT_P (if_info
->a
) && MEM_IN_STRUCT_P (if_info
->b
))
1332 MEM_IN_STRUCT_P (tmp
) = 1;
1333 if (MEM_SCALAR_P (if_info
->a
) && MEM_SCALAR_P (if_info
->b
))
1334 MEM_SCALAR_P (tmp
) = 1;
1335 if (MEM_ALIAS_SET (if_info
->a
) == MEM_ALIAS_SET (if_info
->b
))
1336 set_mem_alias_set (tmp
, MEM_ALIAS_SET (if_info
->a
));
1338 MIN (MEM_ALIGN (if_info
->a
), MEM_ALIGN (if_info
->b
)));
1340 noce_emit_move_insn (if_info
->x
, tmp
);
1342 else if (target
!= x
)
1343 noce_emit_move_insn (x
, target
);
1345 tmp
= end_ifcvt_sequence (if_info
);
1349 emit_insn_before_setloc (tmp
, if_info
->jump
, INSN_LOCATOR (if_info
->insn_a
));
1357 /* For most cases, the simplified condition we found is the best
1358 choice, but this is not the case for the min/max/abs transforms.
1359 For these we wish to know that it is A or B in the condition. */
1362 noce_get_alt_condition (struct noce_if_info
*if_info
, rtx target
,
1365 rtx cond
, set
, insn
;
1368 /* If target is already mentioned in the known condition, return it. */
1369 if (reg_mentioned_p (target
, if_info
->cond
))
1371 *earliest
= if_info
->cond_earliest
;
1372 return if_info
->cond
;
1375 set
= pc_set (if_info
->jump
);
1376 cond
= XEXP (SET_SRC (set
), 0);
1378 = GET_CODE (XEXP (SET_SRC (set
), 2)) == LABEL_REF
1379 && XEXP (XEXP (SET_SRC (set
), 2), 0) == JUMP_LABEL (if_info
->jump
);
1381 /* If we're looking for a constant, try to make the conditional
1382 have that constant in it. There are two reasons why it may
1383 not have the constant we want:
1385 1. GCC may have needed to put the constant in a register, because
1386 the target can't compare directly against that constant. For
1387 this case, we look for a SET immediately before the comparison
1388 that puts a constant in that register.
1390 2. GCC may have canonicalized the conditional, for example
1391 replacing "if x < 4" with "if x <= 3". We can undo that (or
1392 make equivalent types of changes) to get the constants we need
1393 if they're off by one in the right direction. */
1395 if (GET_CODE (target
) == CONST_INT
)
1397 enum rtx_code code
= GET_CODE (if_info
->cond
);
1398 rtx op_a
= XEXP (if_info
->cond
, 0);
1399 rtx op_b
= XEXP (if_info
->cond
, 1);
1402 /* First, look to see if we put a constant in a register. */
1403 prev_insn
= PREV_INSN (if_info
->cond_earliest
);
1405 && INSN_P (prev_insn
)
1406 && GET_CODE (PATTERN (prev_insn
)) == SET
)
1408 rtx src
= find_reg_equal_equiv_note (prev_insn
);
1410 src
= SET_SRC (PATTERN (prev_insn
));
1411 if (GET_CODE (src
) == CONST_INT
)
1413 if (rtx_equal_p (op_a
, SET_DEST (PATTERN (prev_insn
))))
1415 else if (rtx_equal_p (op_b
, SET_DEST (PATTERN (prev_insn
))))
1418 if (GET_CODE (op_a
) == CONST_INT
)
1423 code
= swap_condition (code
);
1428 /* Now, look to see if we can get the right constant by
1429 adjusting the conditional. */
1430 if (GET_CODE (op_b
) == CONST_INT
)
1432 HOST_WIDE_INT desired_val
= INTVAL (target
);
1433 HOST_WIDE_INT actual_val
= INTVAL (op_b
);
1438 if (actual_val
== desired_val
+ 1)
1441 op_b
= GEN_INT (desired_val
);
1445 if (actual_val
== desired_val
- 1)
1448 op_b
= GEN_INT (desired_val
);
1452 if (actual_val
== desired_val
- 1)
1455 op_b
= GEN_INT (desired_val
);
1459 if (actual_val
== desired_val
+ 1)
1462 op_b
= GEN_INT (desired_val
);
1470 /* If we made any changes, generate a new conditional that is
1471 equivalent to what we started with, but has the right
1473 if (code
!= GET_CODE (if_info
->cond
)
1474 || op_a
!= XEXP (if_info
->cond
, 0)
1475 || op_b
!= XEXP (if_info
->cond
, 1))
1477 cond
= gen_rtx_fmt_ee (code
, GET_MODE (cond
), op_a
, op_b
);
1478 *earliest
= if_info
->cond_earliest
;
1483 cond
= canonicalize_condition (if_info
->jump
, cond
, reverse
,
1484 earliest
, target
, false);
1485 if (! cond
|| ! reg_mentioned_p (target
, cond
))
1488 /* We almost certainly searched back to a different place.
1489 Need to re-verify correct lifetimes. */
1491 /* X may not be mentioned in the range (cond_earliest, jump]. */
1492 for (insn
= if_info
->jump
; insn
!= *earliest
; insn
= PREV_INSN (insn
))
1493 if (INSN_P (insn
) && reg_overlap_mentioned_p (if_info
->x
, PATTERN (insn
)))
1496 /* A and B may not be modified in the range [cond_earliest, jump). */
1497 for (insn
= *earliest
; insn
!= if_info
->jump
; insn
= NEXT_INSN (insn
))
1499 && (modified_in_p (if_info
->a
, insn
)
1500 || modified_in_p (if_info
->b
, insn
)))
1506 /* Convert "if (a < b) x = a; else x = b;" to "x = min(a, b);", etc. */
1509 noce_try_minmax (struct noce_if_info
*if_info
)
1511 rtx cond
, earliest
, target
, seq
;
1512 enum rtx_code code
, op
;
1515 /* ??? Can't guarantee that expand_binop won't create pseudos. */
1519 /* ??? Reject modes with NaNs or signed zeros since we don't know how
1520 they will be resolved with an SMIN/SMAX. It wouldn't be too hard
1521 to get the target to tell us... */
1522 if (HONOR_SIGNED_ZEROS (GET_MODE (if_info
->x
))
1523 || HONOR_NANS (GET_MODE (if_info
->x
)))
1526 cond
= noce_get_alt_condition (if_info
, if_info
->a
, &earliest
);
1530 /* Verify the condition is of the form we expect, and canonicalize
1531 the comparison code. */
1532 code
= GET_CODE (cond
);
1533 if (rtx_equal_p (XEXP (cond
, 0), if_info
->a
))
1535 if (! rtx_equal_p (XEXP (cond
, 1), if_info
->b
))
1538 else if (rtx_equal_p (XEXP (cond
, 1), if_info
->a
))
1540 if (! rtx_equal_p (XEXP (cond
, 0), if_info
->b
))
1542 code
= swap_condition (code
);
1547 /* Determine what sort of operation this is. Note that the code is for
1548 a taken branch, so the code->operation mapping appears backwards. */
1581 target
= expand_simple_binop (GET_MODE (if_info
->x
), op
,
1582 if_info
->a
, if_info
->b
,
1583 if_info
->x
, unsignedp
, OPTAB_WIDEN
);
1589 if (target
!= if_info
->x
)
1590 noce_emit_move_insn (if_info
->x
, target
);
1592 seq
= end_ifcvt_sequence (if_info
);
1596 emit_insn_before_setloc (seq
, if_info
->jump
, INSN_LOCATOR (if_info
->insn_a
));
1597 if_info
->cond
= cond
;
1598 if_info
->cond_earliest
= earliest
;
1603 /* Convert "if (a < 0) x = -a; else x = a;" to "x = abs(a);", etc. */
1606 noce_try_abs (struct noce_if_info
*if_info
)
1608 rtx cond
, earliest
, target
, seq
, a
, b
, c
;
1611 /* ??? Can't guarantee that expand_binop won't create pseudos. */
1615 /* Recognize A and B as constituting an ABS or NABS. */
1618 if (GET_CODE (a
) == NEG
&& rtx_equal_p (XEXP (a
, 0), b
))
1620 else if (GET_CODE (b
) == NEG
&& rtx_equal_p (XEXP (b
, 0), a
))
1622 c
= a
; a
= b
; b
= c
;
1628 cond
= noce_get_alt_condition (if_info
, b
, &earliest
);
1632 /* Verify the condition is of the form we expect. */
1633 if (rtx_equal_p (XEXP (cond
, 0), b
))
1635 else if (rtx_equal_p (XEXP (cond
, 1), b
))
1640 /* Verify that C is zero. Search backward through the block for
1641 a REG_EQUAL note if necessary. */
1644 rtx insn
, note
= NULL
;
1645 for (insn
= earliest
;
1646 insn
!= BB_HEAD (if_info
->test_bb
);
1647 insn
= PREV_INSN (insn
))
1649 && ((note
= find_reg_note (insn
, REG_EQUAL
, c
))
1650 || (note
= find_reg_note (insn
, REG_EQUIV
, c
))))
1657 && GET_CODE (XEXP (c
, 0)) == SYMBOL_REF
1658 && CONSTANT_POOL_ADDRESS_P (XEXP (c
, 0)))
1659 c
= get_pool_constant (XEXP (c
, 0));
1661 /* Work around funny ideas get_condition has wrt canonicalization.
1662 Note that these rtx constants are known to be CONST_INT, and
1663 therefore imply integer comparisons. */
1664 if (c
== constm1_rtx
&& GET_CODE (cond
) == GT
)
1666 else if (c
== const1_rtx
&& GET_CODE (cond
) == LT
)
1668 else if (c
!= CONST0_RTX (GET_MODE (b
)))
1671 /* Determine what sort of operation this is. */
1672 switch (GET_CODE (cond
))
1691 target
= expand_abs_nojump (GET_MODE (if_info
->x
), b
, if_info
->x
, 1);
1693 /* ??? It's a quandary whether cmove would be better here, especially
1694 for integers. Perhaps combine will clean things up. */
1695 if (target
&& negate
)
1696 target
= expand_simple_unop (GET_MODE (target
), NEG
, target
, if_info
->x
, 0);
1704 if (target
!= if_info
->x
)
1705 noce_emit_move_insn (if_info
->x
, target
);
1707 seq
= end_ifcvt_sequence (if_info
);
1711 emit_insn_before_setloc (seq
, if_info
->jump
, INSN_LOCATOR (if_info
->insn_a
));
1712 if_info
->cond
= cond
;
1713 if_info
->cond_earliest
= earliest
;
1718 /* Convert "if (m < 0) x = b; else x = 0;" to "x = (m >> C) & b;". */
1721 noce_try_sign_mask (struct noce_if_info
*if_info
)
1723 rtx cond
, t
, m
, c
, seq
;
1724 enum machine_mode mode
;
1730 cond
= if_info
->cond
;
1731 code
= GET_CODE (cond
);
1736 if (if_info
->a
== const0_rtx
)
1738 if ((code
== LT
&& c
== const0_rtx
)
1739 || (code
== LE
&& c
== constm1_rtx
))
1742 else if (if_info
->b
== const0_rtx
)
1744 if ((code
== GE
&& c
== const0_rtx
)
1745 || (code
== GT
&& c
== constm1_rtx
))
1749 if (! t
|| side_effects_p (t
))
1752 /* We currently don't handle different modes. */
1753 mode
= GET_MODE (t
);
1754 if (GET_MODE (m
) != mode
)
1757 /* This is only profitable if T is cheap, or T is unconditionally
1758 executed/evaluated in the original insn sequence. */
1759 if (rtx_cost (t
, SET
) >= COSTS_N_INSNS (2)
1760 && (!if_info
->b_unconditional
1761 || t
!= if_info
->b
))
1765 /* Use emit_store_flag to generate "m < 0 ? -1 : 0" instead of expanding
1766 "(signed) m >> 31" directly. This benefits targets with specialized
1767 insns to obtain the signmask, but still uses ashr_optab otherwise. */
1768 m
= emit_store_flag (gen_reg_rtx (mode
), LT
, m
, const0_rtx
, mode
, 0, -1);
1769 t
= m
? expand_binop (mode
, and_optab
, m
, t
, NULL_RTX
, 0, OPTAB_DIRECT
)
1778 noce_emit_move_insn (if_info
->x
, t
);
1780 seq
= end_ifcvt_sequence (if_info
);
1784 emit_insn_before_setloc (seq
, if_info
->jump
, INSN_LOCATOR (if_info
->insn_a
));
1789 /* Similar to get_condition, only the resulting condition must be
1790 valid at JUMP, instead of at EARLIEST. */
1793 noce_get_condition (rtx jump
, rtx
*earliest
)
1795 rtx cond
, set
, tmp
, insn
;
1798 if (! any_condjump_p (jump
))
1801 set
= pc_set (jump
);
1803 /* If this branches to JUMP_LABEL when the condition is false,
1804 reverse the condition. */
1805 reverse
= (GET_CODE (XEXP (SET_SRC (set
), 2)) == LABEL_REF
1806 && XEXP (XEXP (SET_SRC (set
), 2), 0) == JUMP_LABEL (jump
));
1808 /* If the condition variable is a register and is MODE_INT, accept it. */
1810 cond
= XEXP (SET_SRC (set
), 0);
1811 tmp
= XEXP (cond
, 0);
1812 if (REG_P (tmp
) && GET_MODE_CLASS (GET_MODE (tmp
)) == MODE_INT
)
1817 cond
= gen_rtx_fmt_ee (reverse_condition (GET_CODE (cond
)),
1818 GET_MODE (cond
), tmp
, XEXP (cond
, 1));
1822 /* Otherwise, fall back on canonicalize_condition to do the dirty
1823 work of manipulating MODE_CC values and COMPARE rtx codes. */
1825 tmp
= canonicalize_condition (jump
, cond
, reverse
, earliest
, NULL_RTX
,
1830 /* We are going to insert code before JUMP, not before EARLIEST.
1831 We must therefore be certain that the given condition is valid
1832 at JUMP by virtue of not having been modified since. */
1833 for (insn
= *earliest
; insn
!= jump
; insn
= NEXT_INSN (insn
))
1834 if (INSN_P (insn
) && modified_in_p (tmp
, insn
))
1839 /* The condition was modified. See if we can get a partial result
1840 that doesn't follow all the reversals. Perhaps combine can fold
1841 them together later. */
1842 tmp
= XEXP (tmp
, 0);
1843 if (!REG_P (tmp
) || GET_MODE_CLASS (GET_MODE (tmp
)) != MODE_INT
)
1845 tmp
= canonicalize_condition (jump
, cond
, reverse
, earliest
, tmp
,
1850 /* For sanity's sake, re-validate the new result. */
1851 for (insn
= *earliest
; insn
!= jump
; insn
= NEXT_INSN (insn
))
1852 if (INSN_P (insn
) && modified_in_p (tmp
, insn
))
1858 /* Return true if OP is ok for if-then-else processing. */
1861 noce_operand_ok (rtx op
)
1863 /* We special-case memories, so handle any of them with
1864 no address side effects. */
1866 return ! side_effects_p (XEXP (op
, 0));
1868 if (side_effects_p (op
))
1871 return ! may_trap_p (op
);
1874 /* Given a simple IF-THEN or IF-THEN-ELSE block, attempt to convert it
1875 without using conditional execution. Return TRUE if we were
1876 successful at converting the block. */
1879 noce_process_if_block (struct ce_if_block
* ce_info
)
1881 basic_block test_bb
= ce_info
->test_bb
; /* test block */
1882 basic_block then_bb
= ce_info
->then_bb
; /* THEN */
1883 basic_block else_bb
= ce_info
->else_bb
; /* ELSE or NULL */
1884 struct noce_if_info if_info
;
1887 rtx orig_x
, x
, a
, b
;
1890 /* We're looking for patterns of the form
1892 (1) if (...) x = a; else x = b;
1893 (2) x = b; if (...) x = a;
1894 (3) if (...) x = a; // as if with an initial x = x.
1896 The later patterns require jumps to be more expensive.
1898 ??? For future expansion, look for multiple X in such patterns. */
1900 /* If test is comprised of && or || elements, don't handle it unless it is
1901 the special case of && elements without an ELSE block. */
1902 if (ce_info
->num_multiple_test_blocks
)
1904 if (else_bb
|| ! ce_info
->and_and_p
)
1907 ce_info
->test_bb
= test_bb
= ce_info
->last_test_bb
;
1908 ce_info
->num_multiple_test_blocks
= 0;
1909 ce_info
->num_and_and_blocks
= 0;
1910 ce_info
->num_or_or_blocks
= 0;
1913 /* If this is not a standard conditional jump, we can't parse it. */
1914 jump
= BB_END (test_bb
);
1915 cond
= noce_get_condition (jump
, &if_info
.cond_earliest
);
1919 /* If the conditional jump is more than just a conditional
1920 jump, then we can not do if-conversion on this block. */
1921 if (! onlyjump_p (jump
))
1924 /* We must be comparing objects whose modes imply the size. */
1925 if (GET_MODE (XEXP (cond
, 0)) == BLKmode
)
1928 /* Look for one of the potential sets. */
1929 insn_a
= first_active_insn (then_bb
);
1931 || insn_a
!= last_active_insn (then_bb
, FALSE
)
1932 || (set_a
= single_set (insn_a
)) == NULL_RTX
)
1935 x
= SET_DEST (set_a
);
1936 a
= SET_SRC (set_a
);
1938 /* Look for the other potential set. Make sure we've got equivalent
1940 /* ??? This is overconservative. Storing to two different mems is
1941 as easy as conditionally computing the address. Storing to a
1942 single mem merely requires a scratch memory to use as one of the
1943 destination addresses; often the memory immediately below the
1944 stack pointer is available for this. */
1948 insn_b
= first_active_insn (else_bb
);
1950 || insn_b
!= last_active_insn (else_bb
, FALSE
)
1951 || (set_b
= single_set (insn_b
)) == NULL_RTX
1952 || ! rtx_equal_p (x
, SET_DEST (set_b
)))
1957 insn_b
= prev_nonnote_insn (if_info
.cond_earliest
);
1958 /* We're going to be moving the evaluation of B down from above
1959 COND_EARLIEST to JUMP. Make sure the relevant data is still
1962 || !NONJUMP_INSN_P (insn_b
)
1963 || (set_b
= single_set (insn_b
)) == NULL_RTX
1964 || ! rtx_equal_p (x
, SET_DEST (set_b
))
1965 || reg_overlap_mentioned_p (x
, SET_SRC (set_b
))
1966 || modified_between_p (SET_SRC (set_b
),
1967 PREV_INSN (if_info
.cond_earliest
), jump
)
1968 /* Likewise with X. In particular this can happen when
1969 noce_get_condition looks farther back in the instruction
1970 stream than one might expect. */
1971 || reg_overlap_mentioned_p (x
, cond
)
1972 || reg_overlap_mentioned_p (x
, a
)
1973 || modified_between_p (x
, PREV_INSN (if_info
.cond_earliest
), jump
))
1974 insn_b
= set_b
= NULL_RTX
;
1977 /* If x has side effects then only the if-then-else form is safe to
1978 convert. But even in that case we would need to restore any notes
1979 (such as REG_INC) at then end. That can be tricky if
1980 noce_emit_move_insn expands to more than one insn, so disable the
1981 optimization entirely for now if there are side effects. */
1982 if (side_effects_p (x
))
1985 b
= (set_b
? SET_SRC (set_b
) : x
);
1987 /* Only operate on register destinations, and even then avoid extending
1988 the lifetime of hard registers on small register class machines. */
1991 || (SMALL_REGISTER_CLASSES
1992 && REGNO (x
) < FIRST_PSEUDO_REGISTER
))
1994 if (no_new_pseudos
|| GET_MODE (x
) == BLKmode
)
1996 x
= gen_reg_rtx (GET_MODE (GET_CODE (x
) == STRICT_LOW_PART
1997 ? XEXP (x
, 0) : x
));
2000 /* Don't operate on sources that may trap or are volatile. */
2001 if (! noce_operand_ok (a
) || ! noce_operand_ok (b
))
2004 /* Set up the info block for our subroutines. */
2005 if_info
.test_bb
= test_bb
;
2006 if_info
.cond
= cond
;
2007 if_info
.jump
= jump
;
2008 if_info
.insn_a
= insn_a
;
2009 if_info
.insn_b
= insn_b
;
2013 if_info
.b_unconditional
= else_bb
== 0;
2015 /* Try optimizations in some approximation of a useful order. */
2016 /* ??? Should first look to see if X is live incoming at all. If it
2017 isn't, we don't need anything but an unconditional set. */
2019 /* Look and see if A and B are really the same. Avoid creating silly
2020 cmove constructs that no one will fix up later. */
2021 if (rtx_equal_p (a
, b
))
2023 /* If we have an INSN_B, we don't have to create any new rtl. Just
2024 move the instruction that we already have. If we don't have an
2025 INSN_B, that means that A == X, and we've got a noop move. In
2026 that case don't do anything and let the code below delete INSN_A. */
2027 if (insn_b
&& else_bb
)
2031 if (else_bb
&& insn_b
== BB_END (else_bb
))
2032 BB_END (else_bb
) = PREV_INSN (insn_b
);
2033 reorder_insns (insn_b
, insn_b
, PREV_INSN (jump
));
2035 /* If there was a REG_EQUAL note, delete it since it may have been
2036 true due to this insn being after a jump. */
2037 if ((note
= find_reg_note (insn_b
, REG_EQUAL
, NULL_RTX
)) != 0)
2038 remove_note (insn_b
, note
);
2042 /* If we have "x = b; if (...) x = a;", and x has side-effects, then
2043 x must be executed twice. */
2044 else if (insn_b
&& side_effects_p (orig_x
))
2051 /* Disallow the "if (...) x = a;" form (with an implicit "else x = x;")
2052 for most optimizations if writing to x may trap, i.e. it's a memory
2053 other than a static var or a stack slot. */
2056 && ! MEM_NOTRAP_P (orig_x
)
2057 && rtx_addr_can_trap_p (XEXP (orig_x
, 0)))
2059 if (HAVE_conditional_move
)
2061 if (noce_try_cmove (&if_info
))
2063 if (! HAVE_conditional_execution
2064 && noce_try_cmove_arith (&if_info
))
2070 if (noce_try_move (&if_info
))
2072 if (noce_try_store_flag (&if_info
))
2074 if (noce_try_minmax (&if_info
))
2076 if (noce_try_abs (&if_info
))
2078 if (HAVE_conditional_move
2079 && noce_try_cmove (&if_info
))
2081 if (! HAVE_conditional_execution
)
2083 if (noce_try_store_flag_constants (&if_info
))
2085 if (noce_try_addcc (&if_info
))
2087 if (noce_try_store_flag_mask (&if_info
))
2089 if (HAVE_conditional_move
2090 && noce_try_cmove_arith (&if_info
))
2092 if (noce_try_sign_mask (&if_info
))
2099 /* The original sets may now be killed. */
2100 delete_insn (insn_a
);
2102 /* Several special cases here: First, we may have reused insn_b above,
2103 in which case insn_b is now NULL. Second, we want to delete insn_b
2104 if it came from the ELSE block, because follows the now correct
2105 write that appears in the TEST block. However, if we got insn_b from
2106 the TEST block, it may in fact be loading data needed for the comparison.
2107 We'll let life_analysis remove the insn if it's really dead. */
2108 if (insn_b
&& else_bb
)
2109 delete_insn (insn_b
);
2111 /* The new insns will have been inserted immediately before the jump. We
2112 should be able to remove the jump with impunity, but the condition itself
2113 may have been modified by gcse to be shared across basic blocks. */
2116 /* If we used a temporary, fix it up now. */
2120 noce_emit_move_insn (orig_x
, x
);
2121 insn_b
= get_insns ();
2122 set_used_flags (orig_x
);
2123 unshare_all_rtl_in_chain (insn_b
);
2126 emit_insn_after_setloc (insn_b
, BB_END (test_bb
), INSN_LOCATOR (insn_a
));
2129 /* Merge the blocks! */
2130 merge_if_block (ce_info
);
2135 /* Attempt to convert an IF-THEN or IF-THEN-ELSE block into
2136 straight line code. Return true if successful. */
2139 process_if_block (struct ce_if_block
* ce_info
)
2141 if (! reload_completed
2142 && noce_process_if_block (ce_info
))
2145 if (HAVE_conditional_execution
&& reload_completed
)
2147 /* If we have && and || tests, try to first handle combining the && and
2148 || tests into the conditional code, and if that fails, go back and
2149 handle it without the && and ||, which at present handles the && case
2150 if there was no ELSE block. */
2151 if (cond_exec_process_if_block (ce_info
, TRUE
))
2154 if (ce_info
->num_multiple_test_blocks
)
2158 if (cond_exec_process_if_block (ce_info
, FALSE
))
2166 /* Merge the blocks and mark for local life update. */
2169 merge_if_block (struct ce_if_block
* ce_info
)
2171 basic_block test_bb
= ce_info
->test_bb
; /* last test block */
2172 basic_block then_bb
= ce_info
->then_bb
; /* THEN */
2173 basic_block else_bb
= ce_info
->else_bb
; /* ELSE or NULL */
2174 basic_block join_bb
= ce_info
->join_bb
; /* join block */
2175 basic_block combo_bb
;
2177 /* All block merging is done into the lower block numbers. */
2181 /* Merge any basic blocks to handle && and || subtests. Each of
2182 the blocks are on the fallthru path from the predecessor block. */
2183 if (ce_info
->num_multiple_test_blocks
> 0)
2185 basic_block bb
= test_bb
;
2186 basic_block last_test_bb
= ce_info
->last_test_bb
;
2187 basic_block fallthru
= block_fallthru (bb
);
2192 fallthru
= block_fallthru (bb
);
2193 merge_blocks (combo_bb
, bb
);
2196 while (bb
!= last_test_bb
);
2199 /* Merge TEST block into THEN block. Normally the THEN block won't have a
2200 label, but it might if there were || tests. That label's count should be
2201 zero, and it normally should be removed. */
2205 if (combo_bb
->global_live_at_end
)
2206 COPY_REG_SET (combo_bb
->global_live_at_end
,
2207 then_bb
->global_live_at_end
);
2208 merge_blocks (combo_bb
, then_bb
);
2212 /* The ELSE block, if it existed, had a label. That label count
2213 will almost always be zero, but odd things can happen when labels
2214 get their addresses taken. */
2217 merge_blocks (combo_bb
, else_bb
);
2221 /* If there was no join block reported, that means it was not adjacent
2222 to the others, and so we cannot merge them. */
2226 rtx last
= BB_END (combo_bb
);
2228 /* The outgoing edge for the current COMBO block should already
2229 be correct. Verify this. */
2230 if (combo_bb
->succ
== NULL_EDGE
)
2232 if (find_reg_note (last
, REG_NORETURN
, NULL
))
2234 else if (NONJUMP_INSN_P (last
)
2235 && GET_CODE (PATTERN (last
)) == TRAP_IF
2236 && TRAP_CONDITION (PATTERN (last
)) == const_true_rtx
)
2242 /* There should still be something at the end of the THEN or ELSE
2243 blocks taking us to our final destination. */
2244 else if (JUMP_P (last
))
2246 else if (combo_bb
->succ
->dest
== EXIT_BLOCK_PTR
2248 && SIBLING_CALL_P (last
))
2250 else if ((combo_bb
->succ
->flags
& EDGE_EH
)
2251 && can_throw_internal (last
))
2257 /* The JOIN block may have had quite a number of other predecessors too.
2258 Since we've already merged the TEST, THEN and ELSE blocks, we should
2259 have only one remaining edge from our if-then-else diamond. If there
2260 is more than one remaining edge, it must come from elsewhere. There
2261 may be zero incoming edges if the THEN block didn't actually join
2262 back up (as with a call to abort). */
2263 else if ((join_bb
->pred
== NULL
2264 || join_bb
->pred
->pred_next
== NULL
)
2265 && join_bb
!= EXIT_BLOCK_PTR
)
2267 /* We can merge the JOIN. */
2268 if (combo_bb
->global_live_at_end
)
2269 COPY_REG_SET (combo_bb
->global_live_at_end
,
2270 join_bb
->global_live_at_end
);
2272 merge_blocks (combo_bb
, join_bb
);
2277 /* We cannot merge the JOIN. */
2279 /* The outgoing edge for the current COMBO block should already
2280 be correct. Verify this. */
2281 if (combo_bb
->succ
->succ_next
!= NULL_EDGE
2282 || combo_bb
->succ
->dest
!= join_bb
)
2285 /* Remove the jump and cruft from the end of the COMBO block. */
2286 if (join_bb
!= EXIT_BLOCK_PTR
)
2287 tidy_fallthru_edge (combo_bb
->succ
);
2290 num_updated_if_blocks
++;
2293 /* Find a block ending in a simple IF condition and try to transform it
2294 in some way. When converting a multi-block condition, put the new code
2295 in the first such block and delete the rest. Return a pointer to this
2296 first block if some transformation was done. Return NULL otherwise. */
2299 find_if_header (basic_block test_bb
, int pass
)
2301 ce_if_block_t ce_info
;
2305 /* The kind of block we're looking for has exactly two successors. */
2306 if ((then_edge
= test_bb
->succ
) == NULL_EDGE
2307 || (else_edge
= then_edge
->succ_next
) == NULL_EDGE
2308 || else_edge
->succ_next
!= NULL_EDGE
)
2311 /* Neither edge should be abnormal. */
2312 if ((then_edge
->flags
& EDGE_COMPLEX
)
2313 || (else_edge
->flags
& EDGE_COMPLEX
))
2316 /* Nor exit the loop. */
2317 if ((then_edge
->flags
& EDGE_LOOP_EXIT
)
2318 || (else_edge
->flags
& EDGE_LOOP_EXIT
))
2321 /* The THEN edge is canonically the one that falls through. */
2322 if (then_edge
->flags
& EDGE_FALLTHRU
)
2324 else if (else_edge
->flags
& EDGE_FALLTHRU
)
2327 else_edge
= then_edge
;
2331 /* Otherwise this must be a multiway branch of some sort. */
2334 memset (&ce_info
, '\0', sizeof (ce_info
));
2335 ce_info
.test_bb
= test_bb
;
2336 ce_info
.then_bb
= then_edge
->dest
;
2337 ce_info
.else_bb
= else_edge
->dest
;
2338 ce_info
.pass
= pass
;
2340 #ifdef IFCVT_INIT_EXTRA_FIELDS
2341 IFCVT_INIT_EXTRA_FIELDS (&ce_info
);
2344 if (find_if_block (&ce_info
))
2347 if (HAVE_trap
&& HAVE_conditional_trap
2348 && find_cond_trap (test_bb
, then_edge
, else_edge
))
2351 if (dom_computed
[CDI_POST_DOMINATORS
] >= DOM_NO_FAST_QUERY
2352 && (! HAVE_conditional_execution
|| reload_completed
))
2354 if (find_if_case_1 (test_bb
, then_edge
, else_edge
))
2356 if (find_if_case_2 (test_bb
, then_edge
, else_edge
))
2364 fprintf (dump_file
, "Conversion succeeded on pass %d.\n", pass
);
2365 return ce_info
.test_bb
;
2368 /* Return true if a block has two edges, one of which falls through to the next
2369 block, and the other jumps to a specific block, so that we can tell if the
2370 block is part of an && test or an || test. Returns either -1 or the number
2371 of non-note, non-jump, non-USE/CLOBBER insns in the block. */
2374 block_jumps_and_fallthru_p (basic_block cur_bb
, basic_block target_bb
)
2377 int fallthru_p
= FALSE
;
2383 if (!cur_bb
|| !target_bb
)
2386 /* If no edges, obviously it doesn't jump or fallthru. */
2387 if (cur_bb
->succ
== NULL_EDGE
)
2390 for (cur_edge
= cur_bb
->succ
;
2391 cur_edge
!= NULL_EDGE
;
2392 cur_edge
= cur_edge
->succ_next
)
2394 if (cur_edge
->flags
& EDGE_COMPLEX
)
2395 /* Anything complex isn't what we want. */
2398 else if (cur_edge
->flags
& EDGE_FALLTHRU
)
2401 else if (cur_edge
->dest
== target_bb
)
2408 if ((jump_p
& fallthru_p
) == 0)
2411 /* Don't allow calls in the block, since this is used to group && and ||
2412 together for conditional execution support. ??? we should support
2413 conditional execution support across calls for IA-64 some day, but
2414 for now it makes the code simpler. */
2415 end
= BB_END (cur_bb
);
2416 insn
= BB_HEAD (cur_bb
);
2418 while (insn
!= NULL_RTX
)
2425 && GET_CODE (PATTERN (insn
)) != USE
2426 && GET_CODE (PATTERN (insn
)) != CLOBBER
)
2432 insn
= NEXT_INSN (insn
);
2438 /* Determine if a given basic block heads a simple IF-THEN or IF-THEN-ELSE
2439 block. If so, we'll try to convert the insns to not require the branch.
2440 Return TRUE if we were successful at converting the block. */
2443 find_if_block (struct ce_if_block
* ce_info
)
2445 basic_block test_bb
= ce_info
->test_bb
;
2446 basic_block then_bb
= ce_info
->then_bb
;
2447 basic_block else_bb
= ce_info
->else_bb
;
2448 basic_block join_bb
= NULL_BLOCK
;
2449 edge then_succ
= then_bb
->succ
;
2450 edge else_succ
= else_bb
->succ
;
2451 int then_predecessors
;
2452 int else_predecessors
;
2456 ce_info
->last_test_bb
= test_bb
;
2458 /* Discover if any fall through predecessors of the current test basic block
2459 were && tests (which jump to the else block) or || tests (which jump to
2461 if (HAVE_conditional_execution
&& reload_completed
2462 && test_bb
->pred
!= NULL_EDGE
2463 && test_bb
->pred
->pred_next
== NULL_EDGE
2464 && test_bb
->pred
->flags
== EDGE_FALLTHRU
)
2466 basic_block bb
= test_bb
->pred
->src
;
2467 basic_block target_bb
;
2468 int max_insns
= MAX_CONDITIONAL_EXECUTE
;
2471 /* Determine if the preceding block is an && or || block. */
2472 if ((n_insns
= block_jumps_and_fallthru_p (bb
, else_bb
)) >= 0)
2474 ce_info
->and_and_p
= TRUE
;
2475 target_bb
= else_bb
;
2477 else if ((n_insns
= block_jumps_and_fallthru_p (bb
, then_bb
)) >= 0)
2479 ce_info
->and_and_p
= FALSE
;
2480 target_bb
= then_bb
;
2483 target_bb
= NULL_BLOCK
;
2485 if (target_bb
&& n_insns
<= max_insns
)
2487 int total_insns
= 0;
2490 ce_info
->last_test_bb
= test_bb
;
2492 /* Found at least one && or || block, look for more. */
2495 ce_info
->test_bb
= test_bb
= bb
;
2496 total_insns
+= n_insns
;
2499 if (bb
->pred
== NULL_EDGE
|| bb
->pred
->pred_next
!= NULL_EDGE
)
2503 n_insns
= block_jumps_and_fallthru_p (bb
, target_bb
);
2505 while (n_insns
>= 0 && (total_insns
+ n_insns
) <= max_insns
);
2507 ce_info
->num_multiple_test_blocks
= blocks
;
2508 ce_info
->num_multiple_test_insns
= total_insns
;
2510 if (ce_info
->and_and_p
)
2511 ce_info
->num_and_and_blocks
= blocks
;
2513 ce_info
->num_or_or_blocks
= blocks
;
2517 /* Count the number of edges the THEN and ELSE blocks have. */
2518 then_predecessors
= 0;
2519 for (cur_edge
= then_bb
->pred
;
2520 cur_edge
!= NULL_EDGE
;
2521 cur_edge
= cur_edge
->pred_next
)
2523 then_predecessors
++;
2524 if (cur_edge
->flags
& EDGE_COMPLEX
)
2528 else_predecessors
= 0;
2529 for (cur_edge
= else_bb
->pred
;
2530 cur_edge
!= NULL_EDGE
;
2531 cur_edge
= cur_edge
->pred_next
)
2533 else_predecessors
++;
2534 if (cur_edge
->flags
& EDGE_COMPLEX
)
2538 /* The THEN block of an IF-THEN combo must have exactly one predecessor,
2539 other than any || blocks which jump to the THEN block. */
2540 if ((then_predecessors
- ce_info
->num_or_or_blocks
) != 1)
2543 /* The THEN block of an IF-THEN combo must have zero or one successors. */
2544 if (then_succ
!= NULL_EDGE
2545 && (then_succ
->succ_next
!= NULL_EDGE
2546 || (then_succ
->flags
& EDGE_COMPLEX
)
2547 || (flow2_completed
&& tablejump_p (BB_END (then_bb
), NULL
, NULL
))))
2550 /* If the THEN block has no successors, conditional execution can still
2551 make a conditional call. Don't do this unless the ELSE block has
2552 only one incoming edge -- the CFG manipulation is too ugly otherwise.
2553 Check for the last insn of the THEN block being an indirect jump, which
2554 is listed as not having any successors, but confuses the rest of the CE
2555 code processing. ??? we should fix this in the future. */
2556 if (then_succ
== NULL
)
2558 if (else_bb
->pred
->pred_next
== NULL_EDGE
)
2560 rtx last_insn
= BB_END (then_bb
);
2563 && NOTE_P (last_insn
)
2564 && last_insn
!= BB_HEAD (then_bb
))
2565 last_insn
= PREV_INSN (last_insn
);
2568 && JUMP_P (last_insn
)
2569 && ! simplejump_p (last_insn
))
2573 else_bb
= NULL_BLOCK
;
2579 /* If the THEN block's successor is the other edge out of the TEST block,
2580 then we have an IF-THEN combo without an ELSE. */
2581 else if (then_succ
->dest
== else_bb
)
2584 else_bb
= NULL_BLOCK
;
2587 /* If the THEN and ELSE block meet in a subsequent block, and the ELSE
2588 has exactly one predecessor and one successor, and the outgoing edge
2589 is not complex, then we have an IF-THEN-ELSE combo. */
2590 else if (else_succ
!= NULL_EDGE
2591 && then_succ
->dest
== else_succ
->dest
2592 && else_bb
->pred
->pred_next
== NULL_EDGE
2593 && else_succ
->succ_next
== NULL_EDGE
2594 && ! (else_succ
->flags
& EDGE_COMPLEX
)
2595 && ! (flow2_completed
&& tablejump_p (BB_END (else_bb
), NULL
, NULL
)))
2596 join_bb
= else_succ
->dest
;
2598 /* Otherwise it is not an IF-THEN or IF-THEN-ELSE combination. */
2602 num_possible_if_blocks
++;
2607 "\nIF-THEN%s block found, pass %d, start block %d "
2608 "[insn %d], then %d [%d]",
2609 (else_bb
) ? "-ELSE" : "",
2612 BB_HEAD (test_bb
) ? (int)INSN_UID (BB_HEAD (test_bb
)) : -1,
2614 BB_HEAD (then_bb
) ? (int)INSN_UID (BB_HEAD (then_bb
)) : -1);
2617 fprintf (dump_file
, ", else %d [%d]",
2619 BB_HEAD (else_bb
) ? (int)INSN_UID (BB_HEAD (else_bb
)) : -1);
2621 fprintf (dump_file
, ", join %d [%d]",
2623 BB_HEAD (join_bb
) ? (int)INSN_UID (BB_HEAD (join_bb
)) : -1);
2625 if (ce_info
->num_multiple_test_blocks
> 0)
2626 fprintf (dump_file
, ", %d %s block%s last test %d [%d]",
2627 ce_info
->num_multiple_test_blocks
,
2628 (ce_info
->and_and_p
) ? "&&" : "||",
2629 (ce_info
->num_multiple_test_blocks
== 1) ? "" : "s",
2630 ce_info
->last_test_bb
->index
,
2631 ((BB_HEAD (ce_info
->last_test_bb
))
2632 ? (int)INSN_UID (BB_HEAD (ce_info
->last_test_bb
))
2635 fputc ('\n', dump_file
);
2638 /* Make sure IF, THEN, and ELSE, blocks are adjacent. Actually, we get the
2639 first condition for free, since we've already asserted that there's a
2640 fallthru edge from IF to THEN. Likewise for the && and || blocks, since
2641 we checked the FALLTHRU flag, those are already adjacent to the last IF
2643 /* ??? As an enhancement, move the ELSE block. Have to deal with
2644 BLOCK notes, if by no other means than aborting the merge if they
2645 exist. Sticky enough I don't want to think about it now. */
2647 if (else_bb
&& (next
= next
->next_bb
) != else_bb
)
2649 if ((next
= next
->next_bb
) != join_bb
&& join_bb
!= EXIT_BLOCK_PTR
)
2657 /* Do the real work. */
2658 ce_info
->else_bb
= else_bb
;
2659 ce_info
->join_bb
= join_bb
;
2661 return process_if_block (ce_info
);
2664 /* Convert a branch over a trap, or a branch
2665 to a trap, into a conditional trap. */
2668 find_cond_trap (basic_block test_bb
, edge then_edge
, edge else_edge
)
2670 basic_block then_bb
= then_edge
->dest
;
2671 basic_block else_bb
= else_edge
->dest
;
2672 basic_block other_bb
, trap_bb
;
2673 rtx trap
, jump
, cond
, cond_earliest
, seq
;
2676 /* Locate the block with the trap instruction. */
2677 /* ??? While we look for no successors, we really ought to allow
2678 EH successors. Need to fix merge_if_block for that to work. */
2679 if ((trap
= block_has_only_trap (then_bb
)) != NULL
)
2680 trap_bb
= then_bb
, other_bb
= else_bb
;
2681 else if ((trap
= block_has_only_trap (else_bb
)) != NULL
)
2682 trap_bb
= else_bb
, other_bb
= then_bb
;
2688 fprintf (dump_file
, "\nTRAP-IF block found, start %d, trap %d\n",
2689 test_bb
->index
, trap_bb
->index
);
2692 /* If this is not a standard conditional jump, we can't parse it. */
2693 jump
= BB_END (test_bb
);
2694 cond
= noce_get_condition (jump
, &cond_earliest
);
2698 /* If the conditional jump is more than just a conditional jump, then
2699 we can not do if-conversion on this block. */
2700 if (! onlyjump_p (jump
))
2703 /* We must be comparing objects whose modes imply the size. */
2704 if (GET_MODE (XEXP (cond
, 0)) == BLKmode
)
2707 /* Reverse the comparison code, if necessary. */
2708 code
= GET_CODE (cond
);
2709 if (then_bb
== trap_bb
)
2711 code
= reversed_comparison_code (cond
, jump
);
2712 if (code
== UNKNOWN
)
2716 /* Attempt to generate the conditional trap. */
2717 seq
= gen_cond_trap (code
, XEXP (cond
, 0),
2719 TRAP_CODE (PATTERN (trap
)));
2725 /* Emit the new insns before cond_earliest. */
2726 emit_insn_before_setloc (seq
, cond_earliest
, INSN_LOCATOR (trap
));
2728 /* Delete the trap block if possible. */
2729 remove_edge (trap_bb
== then_bb
? then_edge
: else_edge
);
2730 if (trap_bb
->pred
== NULL
)
2731 delete_basic_block (trap_bb
);
2733 /* If the non-trap block and the test are now adjacent, merge them.
2734 Otherwise we must insert a direct branch. */
2735 if (test_bb
->next_bb
== other_bb
)
2737 struct ce_if_block new_ce_info
;
2739 memset (&new_ce_info
, '\0', sizeof (new_ce_info
));
2740 new_ce_info
.test_bb
= test_bb
;
2741 new_ce_info
.then_bb
= NULL
;
2742 new_ce_info
.else_bb
= NULL
;
2743 new_ce_info
.join_bb
= other_bb
;
2744 merge_if_block (&new_ce_info
);
2750 lab
= JUMP_LABEL (jump
);
2751 newjump
= emit_jump_insn_after (gen_jump (lab
), jump
);
2752 LABEL_NUSES (lab
) += 1;
2753 JUMP_LABEL (newjump
) = lab
;
2754 emit_barrier_after (newjump
);
2762 /* Subroutine of find_cond_trap: if BB contains only a trap insn,
2766 block_has_only_trap (basic_block bb
)
2770 /* We're not the exit block. */
2771 if (bb
== EXIT_BLOCK_PTR
)
2774 /* The block must have no successors. */
2778 /* The only instruction in the THEN block must be the trap. */
2779 trap
= first_active_insn (bb
);
2780 if (! (trap
== BB_END (bb
)
2781 && GET_CODE (PATTERN (trap
)) == TRAP_IF
2782 && TRAP_CONDITION (PATTERN (trap
)) == const_true_rtx
))
2788 /* Look for IF-THEN-ELSE cases in which one of THEN or ELSE is
2789 transformable, but not necessarily the other. There need be no
2792 Return TRUE if we were successful at converting the block.
2794 Cases we'd like to look at:
2797 if (test) goto over; // x not live
2805 if (! test) goto label;
2808 if (test) goto E; // x not live
2822 (3) // This one's really only interesting for targets that can do
2823 // multiway branching, e.g. IA-64 BBB bundles. For other targets
2824 // it results in multiple branches on a cache line, which often
2825 // does not sit well with predictors.
2827 if (test1) goto E; // predicted not taken
2843 (A) Don't do (2) if the branch is predicted against the block we're
2844 eliminating. Do it anyway if we can eliminate a branch; this requires
2845 that the sole successor of the eliminated block postdominate the other
2848 (B) With CE, on (3) we can steal from both sides of the if, creating
2857 Again, this is most useful if J postdominates.
2859 (C) CE substitutes for helpful life information.
2861 (D) These heuristics need a lot of work. */
2863 /* Tests for case 1 above. */
2866 find_if_case_1 (basic_block test_bb
, edge then_edge
, edge else_edge
)
2868 basic_block then_bb
= then_edge
->dest
;
2869 basic_block else_bb
= else_edge
->dest
, new_bb
;
2870 edge then_succ
= then_bb
->succ
;
2873 /* If we are partitioning hot/cold basic blocks, we don't want to
2874 mess up unconditional or indirect jumps that cross between hot
2875 and cold sections. */
2877 if (flag_reorder_blocks_and_partition
2878 && ((BB_END (then_bb
)
2879 && find_reg_note (BB_END (then_bb
), REG_CROSSING_JUMP
, NULL_RTX
))
2880 || (BB_END (else_bb
)
2881 && find_reg_note (BB_END (else_bb
), REG_CROSSING_JUMP
,
2885 /* THEN has one successor. */
2886 if (!then_succ
|| then_succ
->succ_next
!= NULL
)
2889 /* THEN does not fall through, but is not strange either. */
2890 if (then_succ
->flags
& (EDGE_COMPLEX
| EDGE_FALLTHRU
))
2893 /* THEN has one predecessor. */
2894 if (then_bb
->pred
->pred_next
!= NULL
)
2897 /* THEN must do something. */
2898 if (forwarder_block_p (then_bb
))
2901 num_possible_if_blocks
++;
2904 "\nIF-CASE-1 found, start %d, then %d\n",
2905 test_bb
->index
, then_bb
->index
);
2907 /* THEN is small. */
2908 if (total_bb_rtx_cost (then_bb
) >= COSTS_N_INSNS (BRANCH_COST
))
2911 /* Registers set are dead, or are predicable. */
2912 if (! dead_or_predicable (test_bb
, then_bb
, else_bb
,
2913 then_bb
->succ
->dest
, 1))
2916 /* Conversion went ok, including moving the insns and fixing up the
2917 jump. Adjust the CFG to match. */
2919 bitmap_operation (test_bb
->global_live_at_end
,
2920 else_bb
->global_live_at_start
,
2921 then_bb
->global_live_at_end
, BITMAP_IOR
);
2923 new_bb
= redirect_edge_and_branch_force (FALLTHRU_EDGE (test_bb
), else_bb
);
2924 then_bb_index
= then_bb
->index
;
2925 delete_basic_block (then_bb
);
2927 /* Make rest of code believe that the newly created block is the THEN_BB
2928 block we removed. */
2931 new_bb
->index
= then_bb_index
;
2932 BASIC_BLOCK (then_bb_index
) = new_bb
;
2934 /* We've possibly created jump to next insn, cleanup_cfg will solve that
2938 num_updated_if_blocks
++;
2943 /* Test for case 2 above. */
2946 find_if_case_2 (basic_block test_bb
, edge then_edge
, edge else_edge
)
2948 basic_block then_bb
= then_edge
->dest
;
2949 basic_block else_bb
= else_edge
->dest
;
2950 edge else_succ
= else_bb
->succ
;
2953 /* If we are partitioning hot/cold basic blocks, we don't want to
2954 mess up unconditional or indirect jumps that cross between hot
2955 and cold sections. */
2957 if (flag_reorder_blocks_and_partition
2958 && ((BB_END (then_bb
)
2959 && find_reg_note (BB_END (then_bb
), REG_CROSSING_JUMP
, NULL_RTX
))
2960 || (BB_END (else_bb
)
2961 && find_reg_note (BB_END (else_bb
), REG_CROSSING_JUMP
,
2965 /* ELSE has one successor. */
2966 if (!else_succ
|| else_succ
->succ_next
!= NULL
)
2969 /* ELSE outgoing edge is not complex. */
2970 if (else_succ
->flags
& EDGE_COMPLEX
)
2973 /* ELSE has one predecessor. */
2974 if (else_bb
->pred
->pred_next
!= NULL
)
2977 /* THEN is not EXIT. */
2978 if (then_bb
->index
< 0)
2981 /* ELSE is predicted or SUCC(ELSE) postdominates THEN. */
2982 note
= find_reg_note (BB_END (test_bb
), REG_BR_PROB
, NULL_RTX
);
2983 if (note
&& INTVAL (XEXP (note
, 0)) >= REG_BR_PROB_BASE
/ 2)
2985 else if (else_succ
->dest
->index
< 0
2986 || dominated_by_p (CDI_POST_DOMINATORS
, then_bb
,
2992 num_possible_if_blocks
++;
2995 "\nIF-CASE-2 found, start %d, else %d\n",
2996 test_bb
->index
, else_bb
->index
);
2998 /* ELSE is small. */
2999 if (total_bb_rtx_cost (else_bb
) >= COSTS_N_INSNS (BRANCH_COST
))
3002 /* Registers set are dead, or are predicable. */
3003 if (! dead_or_predicable (test_bb
, else_bb
, then_bb
, else_succ
->dest
, 0))
3006 /* Conversion went ok, including moving the insns and fixing up the
3007 jump. Adjust the CFG to match. */
3009 bitmap_operation (test_bb
->global_live_at_end
,
3010 then_bb
->global_live_at_start
,
3011 else_bb
->global_live_at_end
, BITMAP_IOR
);
3013 delete_basic_block (else_bb
);
3016 num_updated_if_blocks
++;
3018 /* ??? We may now fallthru from one of THEN's successors into a join
3019 block. Rerun cleanup_cfg? Examine things manually? Wait? */
3024 /* A subroutine of dead_or_predicable called through for_each_rtx.
3025 Return 1 if a memory is found. */
3028 find_memory (rtx
*px
, void *data ATTRIBUTE_UNUSED
)
3033 /* Used by the code above to perform the actual rtl transformations.
3034 Return TRUE if successful.
3036 TEST_BB is the block containing the conditional branch. MERGE_BB
3037 is the block containing the code to manipulate. NEW_DEST is the
3038 label TEST_BB should be branching to after the conversion.
3039 REVERSEP is true if the sense of the branch should be reversed. */
3042 dead_or_predicable (basic_block test_bb
, basic_block merge_bb
,
3043 basic_block other_bb
, basic_block new_dest
, int reversep
)
3045 rtx head
, end
, jump
, earliest
= NULL_RTX
, old_dest
, new_label
= NULL_RTX
;
3047 jump
= BB_END (test_bb
);
3049 /* Find the extent of the real code in the merge block. */
3050 head
= BB_HEAD (merge_bb
);
3051 end
= BB_END (merge_bb
);
3054 head
= NEXT_INSN (head
);
3059 head
= end
= NULL_RTX
;
3062 head
= NEXT_INSN (head
);
3069 head
= end
= NULL_RTX
;
3072 end
= PREV_INSN (end
);
3075 /* Disable handling dead code by conditional execution if the machine needs
3076 to do anything funny with the tests, etc. */
3077 #ifndef IFCVT_MODIFY_TESTS
3078 if (HAVE_conditional_execution
)
3080 /* In the conditional execution case, we have things easy. We know
3081 the condition is reversible. We don't have to check life info
3082 because we're going to conditionally execute the code anyway.
3083 All that's left is making sure the insns involved can actually
3088 cond
= cond_exec_get_condition (jump
);
3092 prob_val
= find_reg_note (jump
, REG_BR_PROB
, NULL_RTX
);
3094 prob_val
= XEXP (prob_val
, 0);
3098 enum rtx_code rev
= reversed_comparison_code (cond
, jump
);
3101 cond
= gen_rtx_fmt_ee (rev
, GET_MODE (cond
), XEXP (cond
, 0),
3104 prob_val
= GEN_INT (REG_BR_PROB_BASE
- INTVAL (prob_val
));
3107 if (! cond_exec_process_insns ((ce_if_block_t
*)0, head
, end
, cond
,
3116 /* In the non-conditional execution case, we have to verify that there
3117 are no trapping operations, no calls, no references to memory, and
3118 that any registers modified are dead at the branch site. */
3120 rtx insn
, cond
, prev
;
3121 regset_head merge_set_head
, tmp_head
, test_live_head
, test_set_head
;
3122 regset merge_set
, tmp
, test_live
, test_set
;
3123 struct propagate_block_info
*pbi
;
3126 /* Check for no calls or trapping operations. */
3127 for (insn
= head
; ; insn
= NEXT_INSN (insn
))
3133 if (may_trap_p (PATTERN (insn
)))
3136 /* ??? Even non-trapping memories such as stack frame
3137 references must be avoided. For stores, we collect
3138 no lifetime info; for reads, we'd have to assert
3139 true_dependence false against every store in the
3141 if (for_each_rtx (&PATTERN (insn
), find_memory
, NULL
))
3148 if (! any_condjump_p (jump
))
3151 /* Find the extent of the conditional. */
3152 cond
= noce_get_condition (jump
, &earliest
);
3157 MERGE_SET = set of registers set in MERGE_BB
3158 TEST_LIVE = set of registers live at EARLIEST
3159 TEST_SET = set of registers set between EARLIEST and the
3160 end of the block. */
3162 tmp
= INITIALIZE_REG_SET (tmp_head
);
3163 merge_set
= INITIALIZE_REG_SET (merge_set_head
);
3164 test_live
= INITIALIZE_REG_SET (test_live_head
);
3165 test_set
= INITIALIZE_REG_SET (test_set_head
);
3167 /* ??? bb->local_set is only valid during calculate_global_regs_live,
3168 so we must recompute usage for MERGE_BB. Not so bad, I suppose,
3169 since we've already asserted that MERGE_BB is small. */
3170 propagate_block (merge_bb
, tmp
, merge_set
, merge_set
, 0);
3172 /* For small register class machines, don't lengthen lifetimes of
3173 hard registers before reload. */
3174 if (SMALL_REGISTER_CLASSES
&& ! reload_completed
)
3176 EXECUTE_IF_SET_IN_BITMAP
3179 if (i
< FIRST_PSEUDO_REGISTER
3181 && ! global_regs
[i
])
3186 /* For TEST, we're interested in a range of insns, not a whole block.
3187 Moreover, we're interested in the insns live from OTHER_BB. */
3189 COPY_REG_SET (test_live
, other_bb
->global_live_at_start
);
3190 pbi
= init_propagate_block_info (test_bb
, test_live
, test_set
, test_set
,
3193 for (insn
= jump
; ; insn
= prev
)
3195 prev
= propagate_one_insn (pbi
, insn
);
3196 if (insn
== earliest
)
3200 free_propagate_block_info (pbi
);
3202 /* We can perform the transformation if
3203 MERGE_SET & (TEST_SET | TEST_LIVE)
3205 TEST_SET & merge_bb->global_live_at_start
3208 bitmap_operation (tmp
, test_set
, test_live
, BITMAP_IOR
);
3209 bitmap_operation (tmp
, tmp
, merge_set
, BITMAP_AND
);
3210 EXECUTE_IF_SET_IN_BITMAP(tmp
, 0, i
, fail
= 1);
3212 bitmap_operation (tmp
, test_set
, merge_bb
->global_live_at_start
,
3214 EXECUTE_IF_SET_IN_BITMAP(tmp
, 0, i
, fail
= 1);
3217 FREE_REG_SET (merge_set
);
3218 FREE_REG_SET (test_live
);
3219 FREE_REG_SET (test_set
);
3226 /* We don't want to use normal invert_jump or redirect_jump because
3227 we don't want to delete_insn called. Also, we want to do our own
3228 change group management. */
3230 old_dest
= JUMP_LABEL (jump
);
3231 if (other_bb
!= new_dest
)
3233 new_label
= block_label (new_dest
);
3235 ? ! invert_jump_1 (jump
, new_label
)
3236 : ! redirect_jump_1 (jump
, new_label
))
3240 if (! apply_change_group ())
3243 if (other_bb
!= new_dest
)
3246 LABEL_NUSES (old_dest
) -= 1;
3248 LABEL_NUSES (new_label
) += 1;
3249 JUMP_LABEL (jump
) = new_label
;
3251 invert_br_probabilities (jump
);
3253 redirect_edge_succ (BRANCH_EDGE (test_bb
), new_dest
);
3256 gcov_type count
, probability
;
3257 count
= BRANCH_EDGE (test_bb
)->count
;
3258 BRANCH_EDGE (test_bb
)->count
= FALLTHRU_EDGE (test_bb
)->count
;
3259 FALLTHRU_EDGE (test_bb
)->count
= count
;
3260 probability
= BRANCH_EDGE (test_bb
)->probability
;
3261 BRANCH_EDGE (test_bb
)->probability
3262 = FALLTHRU_EDGE (test_bb
)->probability
;
3263 FALLTHRU_EDGE (test_bb
)->probability
= probability
;
3264 update_br_prob_note (test_bb
);
3268 /* Move the insns out of MERGE_BB to before the branch. */
3271 if (end
== BB_END (merge_bb
))
3272 BB_END (merge_bb
) = PREV_INSN (head
);
3274 if (squeeze_notes (&head
, &end
))
3277 reorder_insns (head
, end
, PREV_INSN (earliest
));
3280 /* Remove the jump and edge if we can. */
3281 if (other_bb
== new_dest
)
3284 remove_edge (BRANCH_EDGE (test_bb
));
3285 /* ??? Can't merge blocks here, as then_bb is still in use.
3286 At minimum, the merge will get done just before bb-reorder. */
3296 /* Main entry point for all if-conversion. */
3299 if_convert (int x_life_data_ok
)
3304 num_possible_if_blocks
= 0;
3305 num_updated_if_blocks
= 0;
3306 num_true_changes
= 0;
3307 life_data_ok
= (x_life_data_ok
!= 0);
3309 if ((! targetm
.cannot_modify_jumps_p ())
3310 && (!flag_reorder_blocks_and_partition
|| !no_new_pseudos
))
3311 mark_loop_exit_edges ();
3313 /* Compute postdominators if we think we'll use them. */
3314 if (HAVE_conditional_execution
|| life_data_ok
)
3315 calculate_dominance_info (CDI_POST_DOMINATORS
);
3320 /* Go through each of the basic blocks looking for things to convert. If we
3321 have conditional execution, we make multiple passes to allow us to handle
3322 IF-THEN{-ELSE} blocks within other IF-THEN{-ELSE} blocks. */
3326 cond_exec_changed_p
= FALSE
;
3329 #ifdef IFCVT_MULTIPLE_DUMPS
3330 if (dump_file
&& pass
> 1)
3331 fprintf (dump_file
, "\n\n========== Pass %d ==========\n", pass
);
3337 while ((new_bb
= find_if_header (bb
, pass
)))
3341 #ifdef IFCVT_MULTIPLE_DUMPS
3342 if (dump_file
&& cond_exec_changed_p
)
3343 print_rtl_with_bb (dump_file
, get_insns ());
3346 while (cond_exec_changed_p
);
3348 #ifdef IFCVT_MULTIPLE_DUMPS
3350 fprintf (dump_file
, "\n\n========== no more changes\n");
3353 free_dominance_info (CDI_POST_DOMINATORS
);
3358 clear_aux_for_blocks ();
3360 /* Rebuild life info for basic blocks that require it. */
3361 if (num_true_changes
&& life_data_ok
)
3363 /* If we allocated new pseudos, we must resize the array for sched1. */
3364 if (max_regno
< max_reg_num ())
3366 max_regno
= max_reg_num ();
3367 allocate_reg_info (max_regno
, FALSE
, FALSE
);
3369 update_life_info_in_dirty_blocks (UPDATE_LIFE_GLOBAL_RM_NOTES
,
3370 PROP_DEATH_NOTES
| PROP_SCAN_DEAD_CODE
3371 | PROP_KILL_DEAD_CODE
);
3374 /* Write the final stats. */
3375 if (dump_file
&& num_possible_if_blocks
> 0)
3378 "\n%d possible IF blocks searched.\n",
3379 num_possible_if_blocks
);
3381 "%d IF blocks converted.\n",
3382 num_updated_if_blocks
);
3384 "%d true changes made.\n\n\n",
3388 #ifdef ENABLE_CHECKING
3389 verify_flow_info ();