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 ((edge) NULL)
69 #define NULL_BLOCK ((basic_block) 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_EACH_EDGE (e
, bb
->succs
)
131 if (find_common_loop (bb
->loop_father
, e
->dest
->loop_father
)
133 e
->flags
|= EDGE_LOOP_EXIT
;
135 e
->flags
&= ~EDGE_LOOP_EXIT
;
141 flow_loops_free (&loops
);
144 /* Count the number of non-jump active insns in BB. */
147 count_bb_insns (basic_block bb
)
150 rtx insn
= BB_HEAD (bb
);
154 if (CALL_P (insn
) || NONJUMP_INSN_P (insn
))
157 if (insn
== BB_END (bb
))
159 insn
= NEXT_INSN (insn
);
165 /* Count the total insn_rtx_cost of non-jump active insns in BB.
166 This function returns -1, if the cost of any instruction could
170 total_bb_rtx_cost (basic_block bb
)
173 rtx insn
= BB_HEAD (bb
);
177 if (NONJUMP_INSN_P (insn
))
179 int cost
= insn_rtx_cost (PATTERN (insn
));
184 else if (CALL_P (insn
))
187 if (insn
== BB_END (bb
))
189 insn
= NEXT_INSN (insn
);
195 /* Return the first non-jump active insn in the basic block. */
198 first_active_insn (basic_block bb
)
200 rtx insn
= BB_HEAD (bb
);
204 if (insn
== BB_END (bb
))
206 insn
= NEXT_INSN (insn
);
209 while (NOTE_P (insn
))
211 if (insn
== BB_END (bb
))
213 insn
= NEXT_INSN (insn
);
222 /* Return the last non-jump active (non-jump) insn in the basic block. */
225 last_active_insn (basic_block bb
, int skip_use_p
)
227 rtx insn
= BB_END (bb
);
228 rtx head
= BB_HEAD (bb
);
233 && NONJUMP_INSN_P (insn
)
234 && GET_CODE (PATTERN (insn
)) == USE
))
238 insn
= PREV_INSN (insn
);
247 /* Return the basic block reached by falling though the basic block BB. */
250 block_fallthru (basic_block bb
)
254 FOR_EACH_EDGE (e
, bb
->succs
)
256 if (e
->flags
& EDGE_FALLTHRU
)
261 return (e
) ? e
->dest
: NULL_BLOCK
;
264 /* Go through a bunch of insns, converting them to conditional
265 execution format if possible. Return TRUE if all of the non-note
266 insns were processed. */
269 cond_exec_process_insns (ce_if_block_t
*ce_info ATTRIBUTE_UNUSED
,
270 /* if block information */rtx start
,
271 /* first insn to look at */rtx end
,
272 /* last insn to look at */rtx test
,
273 /* conditional execution test */rtx prob_val
,
274 /* probability of branch taken. */int mod_ok
)
276 int must_be_last
= FALSE
;
284 for (insn
= start
; ; insn
= NEXT_INSN (insn
))
289 if (!NONJUMP_INSN_P (insn
) && !CALL_P (insn
))
292 /* Remove USE insns that get in the way. */
293 if (reload_completed
&& GET_CODE (PATTERN (insn
)) == USE
)
295 /* ??? Ug. Actually unlinking the thing is problematic,
296 given what we'd have to coordinate with our callers. */
297 SET_INSN_DELETED (insn
);
301 /* Last insn wasn't last? */
305 if (modified_in_p (test
, insn
))
312 /* Now build the conditional form of the instruction. */
313 pattern
= PATTERN (insn
);
314 xtest
= copy_rtx (test
);
316 /* If this is already a COND_EXEC, rewrite the test to be an AND of the
318 if (GET_CODE (pattern
) == COND_EXEC
)
320 if (GET_MODE (xtest
) != GET_MODE (COND_EXEC_TEST (pattern
)))
323 xtest
= gen_rtx_AND (GET_MODE (xtest
), xtest
,
324 COND_EXEC_TEST (pattern
));
325 pattern
= COND_EXEC_CODE (pattern
);
328 pattern
= gen_rtx_COND_EXEC (VOIDmode
, xtest
, pattern
);
330 /* If the machine needs to modify the insn being conditionally executed,
331 say for example to force a constant integer operand into a temp
332 register, do so here. */
333 #ifdef IFCVT_MODIFY_INSN
334 IFCVT_MODIFY_INSN (ce_info
, pattern
, insn
);
339 validate_change (insn
, &PATTERN (insn
), pattern
, 1);
341 if (CALL_P (insn
) && prob_val
)
342 validate_change (insn
, ®_NOTES (insn
),
343 alloc_EXPR_LIST (REG_BR_PROB
, prob_val
,
344 REG_NOTES (insn
)), 1);
354 /* Return the condition for a jump. Do not do any special processing. */
357 cond_exec_get_condition (rtx jump
)
361 if (any_condjump_p (jump
))
362 test_if
= SET_SRC (pc_set (jump
));
365 cond
= XEXP (test_if
, 0);
367 /* If this branches to JUMP_LABEL when the condition is false,
368 reverse the condition. */
369 if (GET_CODE (XEXP (test_if
, 2)) == LABEL_REF
370 && XEXP (XEXP (test_if
, 2), 0) == JUMP_LABEL (jump
))
372 enum rtx_code rev
= reversed_comparison_code (cond
, jump
);
376 cond
= gen_rtx_fmt_ee (rev
, GET_MODE (cond
), XEXP (cond
, 0),
383 /* Given a simple IF-THEN or IF-THEN-ELSE block, attempt to convert it
384 to conditional execution. Return TRUE if we were successful at
385 converting the block. */
388 cond_exec_process_if_block (ce_if_block_t
* ce_info
,
389 /* if block information */int do_multiple_p
)
391 basic_block test_bb
= ce_info
->test_bb
; /* last test block */
392 basic_block then_bb
= ce_info
->then_bb
; /* THEN */
393 basic_block else_bb
= ce_info
->else_bb
; /* ELSE or NULL */
394 rtx test_expr
; /* expression in IF_THEN_ELSE that is tested */
395 rtx then_start
; /* first insn in THEN block */
396 rtx then_end
; /* last insn + 1 in THEN block */
397 rtx else_start
= NULL_RTX
; /* first insn in ELSE block or NULL */
398 rtx else_end
= NULL_RTX
; /* last insn + 1 in ELSE block */
399 int max
; /* max # of insns to convert. */
400 int then_mod_ok
; /* whether conditional mods are ok in THEN */
401 rtx true_expr
; /* test for else block insns */
402 rtx false_expr
; /* test for then block insns */
403 rtx true_prob_val
; /* probability of else block */
404 rtx false_prob_val
; /* probability of then block */
406 enum rtx_code false_code
;
408 /* If test is comprised of && or || elements, and we've failed at handling
409 all of them together, just use the last test if it is the special case of
410 && elements without an ELSE block. */
411 if (!do_multiple_p
&& ce_info
->num_multiple_test_blocks
)
413 if (else_bb
|| ! ce_info
->and_and_p
)
416 ce_info
->test_bb
= test_bb
= ce_info
->last_test_bb
;
417 ce_info
->num_multiple_test_blocks
= 0;
418 ce_info
->num_and_and_blocks
= 0;
419 ce_info
->num_or_or_blocks
= 0;
422 /* Find the conditional jump to the ELSE or JOIN part, and isolate
424 test_expr
= cond_exec_get_condition (BB_END (test_bb
));
428 /* If the conditional jump is more than just a conditional jump,
429 then we can not do conditional execution conversion on this block. */
430 if (! onlyjump_p (BB_END (test_bb
)))
433 /* Collect the bounds of where we're to search, skipping any labels, jumps
434 and notes at the beginning and end of the block. Then count the total
435 number of insns and see if it is small enough to convert. */
436 then_start
= first_active_insn (then_bb
);
437 then_end
= last_active_insn (then_bb
, TRUE
);
438 n_insns
= ce_info
->num_then_insns
= count_bb_insns (then_bb
);
439 max
= MAX_CONDITIONAL_EXECUTE
;
444 else_start
= first_active_insn (else_bb
);
445 else_end
= last_active_insn (else_bb
, TRUE
);
446 n_insns
+= ce_info
->num_else_insns
= count_bb_insns (else_bb
);
452 /* Map test_expr/test_jump into the appropriate MD tests to use on
453 the conditionally executed code. */
455 true_expr
= test_expr
;
457 false_code
= reversed_comparison_code (true_expr
, BB_END (test_bb
));
458 if (false_code
!= UNKNOWN
)
459 false_expr
= gen_rtx_fmt_ee (false_code
, GET_MODE (true_expr
),
460 XEXP (true_expr
, 0), XEXP (true_expr
, 1));
462 false_expr
= NULL_RTX
;
464 #ifdef IFCVT_MODIFY_TESTS
465 /* If the machine description needs to modify the tests, such as setting a
466 conditional execution register from a comparison, it can do so here. */
467 IFCVT_MODIFY_TESTS (ce_info
, true_expr
, false_expr
);
469 /* See if the conversion failed. */
470 if (!true_expr
|| !false_expr
)
474 true_prob_val
= find_reg_note (BB_END (test_bb
), REG_BR_PROB
, NULL_RTX
);
477 true_prob_val
= XEXP (true_prob_val
, 0);
478 false_prob_val
= GEN_INT (REG_BR_PROB_BASE
- INTVAL (true_prob_val
));
481 false_prob_val
= NULL_RTX
;
483 /* If we have && or || tests, do them here. These tests are in the adjacent
484 blocks after the first block containing the test. */
485 if (ce_info
->num_multiple_test_blocks
> 0)
487 basic_block bb
= test_bb
;
488 basic_block last_test_bb
= ce_info
->last_test_bb
;
498 bb
= block_fallthru (bb
);
499 start
= first_active_insn (bb
);
500 end
= last_active_insn (bb
, TRUE
);
502 && ! cond_exec_process_insns (ce_info
, start
, end
, false_expr
,
503 false_prob_val
, FALSE
))
506 /* If the conditional jump is more than just a conditional jump, then
507 we can not do conditional execution conversion on this block. */
508 if (! onlyjump_p (BB_END (bb
)))
511 /* Find the conditional jump and isolate the test. */
512 t
= cond_exec_get_condition (BB_END (bb
));
516 f
= gen_rtx_fmt_ee (reverse_condition (GET_CODE (t
)),
521 if (ce_info
->and_and_p
)
523 t
= gen_rtx_AND (GET_MODE (t
), true_expr
, t
);
524 f
= gen_rtx_IOR (GET_MODE (t
), false_expr
, f
);
528 t
= gen_rtx_IOR (GET_MODE (t
), true_expr
, t
);
529 f
= gen_rtx_AND (GET_MODE (t
), false_expr
, f
);
532 /* If the machine description needs to modify the tests, such as
533 setting a conditional execution register from a comparison, it can
535 #ifdef IFCVT_MODIFY_MULTIPLE_TESTS
536 IFCVT_MODIFY_MULTIPLE_TESTS (ce_info
, bb
, t
, f
);
538 /* See if the conversion failed. */
546 while (bb
!= last_test_bb
);
549 /* For IF-THEN-ELSE blocks, we don't allow modifications of the test
550 on then THEN block. */
551 then_mod_ok
= (else_bb
== NULL_BLOCK
);
553 /* Go through the THEN and ELSE blocks converting the insns if possible
554 to conditional execution. */
558 || ! cond_exec_process_insns (ce_info
, then_start
, then_end
,
559 false_expr
, false_prob_val
,
563 if (else_bb
&& else_end
564 && ! cond_exec_process_insns (ce_info
, else_start
, else_end
,
565 true_expr
, true_prob_val
, TRUE
))
568 /* If we cannot apply the changes, fail. Do not go through the normal fail
569 processing, since apply_change_group will call cancel_changes. */
570 if (! apply_change_group ())
572 #ifdef IFCVT_MODIFY_CANCEL
573 /* Cancel any machine dependent changes. */
574 IFCVT_MODIFY_CANCEL (ce_info
);
579 #ifdef IFCVT_MODIFY_FINAL
580 /* Do any machine dependent final modifications. */
581 IFCVT_MODIFY_FINAL (ce_info
);
584 /* Conversion succeeded. */
586 fprintf (dump_file
, "%d insn%s converted to conditional execution.\n",
587 n_insns
, (n_insns
== 1) ? " was" : "s were");
589 /* Merge the blocks! */
590 merge_if_block (ce_info
);
591 cond_exec_changed_p
= TRUE
;
595 #ifdef IFCVT_MODIFY_CANCEL
596 /* Cancel any machine dependent changes. */
597 IFCVT_MODIFY_CANCEL (ce_info
);
604 /* Used by noce_process_if_block to communicate with its subroutines.
606 The subroutines know that A and B may be evaluated freely. They
607 know that X is a register. They should insert new instructions
608 before cond_earliest. */
615 rtx jump
, cond
, cond_earliest
;
616 /* True if "b" was originally evaluated unconditionally. */
617 bool b_unconditional
;
620 static rtx
noce_emit_store_flag (struct noce_if_info
*, rtx
, int, int);
621 static int noce_try_move (struct noce_if_info
*);
622 static int noce_try_store_flag (struct noce_if_info
*);
623 static int noce_try_addcc (struct noce_if_info
*);
624 static int noce_try_store_flag_constants (struct noce_if_info
*);
625 static int noce_try_store_flag_mask (struct noce_if_info
*);
626 static rtx
noce_emit_cmove (struct noce_if_info
*, rtx
, enum rtx_code
, rtx
,
628 static int noce_try_cmove (struct noce_if_info
*);
629 static int noce_try_cmove_arith (struct noce_if_info
*);
630 static rtx
noce_get_alt_condition (struct noce_if_info
*, rtx
, rtx
*);
631 static int noce_try_minmax (struct noce_if_info
*);
632 static int noce_try_abs (struct noce_if_info
*);
633 static int noce_try_sign_mask (struct noce_if_info
*);
635 /* Helper function for noce_try_store_flag*. */
638 noce_emit_store_flag (struct noce_if_info
*if_info
, rtx x
, int reversep
,
641 rtx cond
= if_info
->cond
;
645 cond_complex
= (! general_operand (XEXP (cond
, 0), VOIDmode
)
646 || ! general_operand (XEXP (cond
, 1), VOIDmode
));
648 /* If earliest == jump, or when the condition is complex, try to
649 build the store_flag insn directly. */
652 cond
= XEXP (SET_SRC (pc_set (if_info
->jump
)), 0);
655 code
= reversed_comparison_code (cond
, if_info
->jump
);
657 code
= GET_CODE (cond
);
659 if ((if_info
->cond_earliest
== if_info
->jump
|| cond_complex
)
660 && (normalize
== 0 || STORE_FLAG_VALUE
== normalize
))
664 tmp
= gen_rtx_fmt_ee (code
, GET_MODE (x
), XEXP (cond
, 0),
666 tmp
= gen_rtx_SET (VOIDmode
, x
, tmp
);
669 tmp
= emit_insn (tmp
);
671 if (recog_memoized (tmp
) >= 0)
677 if_info
->cond_earliest
= if_info
->jump
;
685 /* Don't even try if the comparison operands or the mode of X are weird. */
686 if (cond_complex
|| !SCALAR_INT_MODE_P (GET_MODE (x
)))
689 return emit_store_flag (x
, code
, XEXP (cond
, 0),
690 XEXP (cond
, 1), VOIDmode
,
691 (code
== LTU
|| code
== LEU
692 || code
== GEU
|| code
== GTU
), normalize
);
695 /* Emit instruction to move an rtx, possibly into STRICT_LOW_PART.
696 X is the destination/target and Y is the value to copy. */
699 noce_emit_move_insn (rtx x
, rtx y
)
701 enum machine_mode outmode
, inmode
;
705 if (GET_CODE (x
) != STRICT_LOW_PART
)
707 emit_move_insn (x
, y
);
712 inner
= XEXP (outer
, 0);
713 outmode
= GET_MODE (outer
);
714 inmode
= GET_MODE (inner
);
715 bitpos
= SUBREG_BYTE (outer
) * BITS_PER_UNIT
;
716 store_bit_field (inner
, GET_MODE_BITSIZE (outmode
), bitpos
, outmode
, y
);
719 /* Return sequence of instructions generated by if conversion. This
720 function calls end_sequence() to end the current stream, ensures
721 that are instructions are unshared, recognizable non-jump insns.
722 On failure, this function returns a NULL_RTX. */
725 end_ifcvt_sequence (struct noce_if_info
*if_info
)
728 rtx seq
= get_insns ();
730 set_used_flags (if_info
->x
);
731 set_used_flags (if_info
->cond
);
732 unshare_all_rtl_in_chain (seq
);
735 /* Make sure that all of the instructions emitted are recognizable,
736 and that we haven't introduced a new jump instruction.
737 As an exercise for the reader, build a general mechanism that
738 allows proper placement of required clobbers. */
739 for (insn
= seq
; insn
; insn
= NEXT_INSN (insn
))
741 || recog_memoized (insn
) == -1)
747 /* Convert "if (a != b) x = a; else x = b" into "x = a" and
748 "if (a == b) x = a; else x = b" into "x = b". */
751 noce_try_move (struct noce_if_info
*if_info
)
753 rtx cond
= if_info
->cond
;
754 enum rtx_code code
= GET_CODE (cond
);
757 if (code
!= NE
&& code
!= EQ
)
760 /* This optimization isn't valid if either A or B could be a NaN
762 if (HONOR_NANS (GET_MODE (if_info
->x
))
763 || HONOR_SIGNED_ZEROS (GET_MODE (if_info
->x
)))
766 /* Check whether the operands of the comparison are A and in
768 if ((rtx_equal_p (if_info
->a
, XEXP (cond
, 0))
769 && rtx_equal_p (if_info
->b
, XEXP (cond
, 1)))
770 || (rtx_equal_p (if_info
->a
, XEXP (cond
, 1))
771 && rtx_equal_p (if_info
->b
, XEXP (cond
, 0))))
773 y
= (code
== EQ
) ? if_info
->a
: if_info
->b
;
775 /* Avoid generating the move if the source is the destination. */
776 if (! rtx_equal_p (if_info
->x
, y
))
779 noce_emit_move_insn (if_info
->x
, y
);
780 seq
= end_ifcvt_sequence (if_info
);
784 emit_insn_before_setloc (seq
, if_info
->jump
,
785 INSN_LOCATOR (if_info
->insn_a
));
792 /* Convert "if (test) x = 1; else x = 0".
794 Only try 0 and STORE_FLAG_VALUE here. Other combinations will be
795 tried in noce_try_store_flag_constants after noce_try_cmove has had
796 a go at the conversion. */
799 noce_try_store_flag (struct noce_if_info
*if_info
)
804 if (GET_CODE (if_info
->b
) == CONST_INT
805 && INTVAL (if_info
->b
) == STORE_FLAG_VALUE
806 && if_info
->a
== const0_rtx
)
808 else if (if_info
->b
== const0_rtx
809 && GET_CODE (if_info
->a
) == CONST_INT
810 && INTVAL (if_info
->a
) == STORE_FLAG_VALUE
811 && (reversed_comparison_code (if_info
->cond
, if_info
->jump
)
819 target
= noce_emit_store_flag (if_info
, if_info
->x
, reversep
, 0);
822 if (target
!= if_info
->x
)
823 noce_emit_move_insn (if_info
->x
, target
);
825 seq
= end_ifcvt_sequence (if_info
);
829 emit_insn_before_setloc (seq
, if_info
->jump
,
830 INSN_LOCATOR (if_info
->insn_a
));
840 /* Convert "if (test) x = a; else x = b", for A and B constant. */
843 noce_try_store_flag_constants (struct noce_if_info
*if_info
)
847 HOST_WIDE_INT itrue
, ifalse
, diff
, tmp
;
848 int normalize
, can_reverse
;
849 enum machine_mode mode
;
852 && GET_CODE (if_info
->a
) == CONST_INT
853 && GET_CODE (if_info
->b
) == CONST_INT
)
855 mode
= GET_MODE (if_info
->x
);
856 ifalse
= INTVAL (if_info
->a
);
857 itrue
= INTVAL (if_info
->b
);
859 /* Make sure we can represent the difference between the two values. */
860 if ((itrue
- ifalse
> 0)
861 != ((ifalse
< 0) != (itrue
< 0) ? ifalse
< 0 : ifalse
< itrue
))
864 diff
= trunc_int_for_mode (itrue
- ifalse
, mode
);
866 can_reverse
= (reversed_comparison_code (if_info
->cond
, if_info
->jump
)
870 if (diff
== STORE_FLAG_VALUE
|| diff
== -STORE_FLAG_VALUE
)
872 else if (ifalse
== 0 && exact_log2 (itrue
) >= 0
873 && (STORE_FLAG_VALUE
== 1
874 || BRANCH_COST
>= 2))
876 else if (itrue
== 0 && exact_log2 (ifalse
) >= 0 && can_reverse
877 && (STORE_FLAG_VALUE
== 1 || BRANCH_COST
>= 2))
878 normalize
= 1, reversep
= 1;
880 && (STORE_FLAG_VALUE
== -1
881 || BRANCH_COST
>= 2))
883 else if (ifalse
== -1 && can_reverse
884 && (STORE_FLAG_VALUE
== -1 || BRANCH_COST
>= 2))
885 normalize
= -1, reversep
= 1;
886 else if ((BRANCH_COST
>= 2 && STORE_FLAG_VALUE
== -1)
894 tmp
= itrue
; itrue
= ifalse
; ifalse
= tmp
;
895 diff
= trunc_int_for_mode (-diff
, mode
);
899 target
= noce_emit_store_flag (if_info
, if_info
->x
, reversep
, normalize
);
906 /* if (test) x = 3; else x = 4;
907 => x = 3 + (test == 0); */
908 if (diff
== STORE_FLAG_VALUE
|| diff
== -STORE_FLAG_VALUE
)
910 target
= expand_simple_binop (mode
,
911 (diff
== STORE_FLAG_VALUE
913 GEN_INT (ifalse
), target
, if_info
->x
, 0,
917 /* if (test) x = 8; else x = 0;
918 => x = (test != 0) << 3; */
919 else if (ifalse
== 0 && (tmp
= exact_log2 (itrue
)) >= 0)
921 target
= expand_simple_binop (mode
, ASHIFT
,
922 target
, GEN_INT (tmp
), if_info
->x
, 0,
926 /* if (test) x = -1; else x = b;
927 => x = -(test != 0) | b; */
928 else if (itrue
== -1)
930 target
= expand_simple_binop (mode
, IOR
,
931 target
, GEN_INT (ifalse
), if_info
->x
, 0,
935 /* if (test) x = a; else x = b;
936 => x = (-(test != 0) & (b - a)) + a; */
939 target
= expand_simple_binop (mode
, AND
,
940 target
, GEN_INT (diff
), if_info
->x
, 0,
943 target
= expand_simple_binop (mode
, PLUS
,
944 target
, GEN_INT (ifalse
),
945 if_info
->x
, 0, OPTAB_WIDEN
);
954 if (target
!= if_info
->x
)
955 noce_emit_move_insn (if_info
->x
, target
);
957 seq
= end_ifcvt_sequence (if_info
);
961 emit_insn_before_setloc (seq
, if_info
->jump
,
962 INSN_LOCATOR (if_info
->insn_a
));
969 /* Convert "if (test) foo++" into "foo += (test != 0)", and
970 similarly for "foo--". */
973 noce_try_addcc (struct noce_if_info
*if_info
)
976 int subtract
, normalize
;
979 && GET_CODE (if_info
->a
) == PLUS
980 && rtx_equal_p (XEXP (if_info
->a
, 0), if_info
->b
)
981 && (reversed_comparison_code (if_info
->cond
, if_info
->jump
)
984 rtx cond
= if_info
->cond
;
985 enum rtx_code code
= reversed_comparison_code (cond
, if_info
->jump
);
987 /* First try to use addcc pattern. */
988 if (general_operand (XEXP (cond
, 0), VOIDmode
)
989 && general_operand (XEXP (cond
, 1), VOIDmode
))
992 target
= emit_conditional_add (if_info
->x
, code
,
997 XEXP (if_info
->a
, 1),
998 GET_MODE (if_info
->x
),
999 (code
== LTU
|| code
== GEU
1000 || code
== LEU
|| code
== GTU
));
1003 if (target
!= if_info
->x
)
1004 noce_emit_move_insn (if_info
->x
, target
);
1006 seq
= end_ifcvt_sequence (if_info
);
1010 emit_insn_before_setloc (seq
, if_info
->jump
,
1011 INSN_LOCATOR (if_info
->insn_a
));
1017 /* If that fails, construct conditional increment or decrement using
1019 if (BRANCH_COST
>= 2
1020 && (XEXP (if_info
->a
, 1) == const1_rtx
1021 || XEXP (if_info
->a
, 1) == constm1_rtx
))
1024 if (STORE_FLAG_VALUE
== INTVAL (XEXP (if_info
->a
, 1)))
1025 subtract
= 0, normalize
= 0;
1026 else if (-STORE_FLAG_VALUE
== INTVAL (XEXP (if_info
->a
, 1)))
1027 subtract
= 1, normalize
= 0;
1029 subtract
= 0, normalize
= INTVAL (XEXP (if_info
->a
, 1));
1032 target
= noce_emit_store_flag (if_info
,
1033 gen_reg_rtx (GET_MODE (if_info
->x
)),
1037 target
= expand_simple_binop (GET_MODE (if_info
->x
),
1038 subtract
? MINUS
: PLUS
,
1039 if_info
->b
, target
, if_info
->x
,
1043 if (target
!= if_info
->x
)
1044 noce_emit_move_insn (if_info
->x
, target
);
1046 seq
= end_ifcvt_sequence (if_info
);
1050 emit_insn_before_setloc (seq
, if_info
->jump
,
1051 INSN_LOCATOR (if_info
->insn_a
));
1061 /* Convert "if (test) x = 0;" to "x &= -(test == 0);" */
1064 noce_try_store_flag_mask (struct noce_if_info
*if_info
)
1070 if (! no_new_pseudos
1071 && (BRANCH_COST
>= 2
1072 || STORE_FLAG_VALUE
== -1)
1073 && ((if_info
->a
== const0_rtx
1074 && rtx_equal_p (if_info
->b
, if_info
->x
))
1075 || ((reversep
= (reversed_comparison_code (if_info
->cond
,
1078 && if_info
->b
== const0_rtx
1079 && rtx_equal_p (if_info
->a
, if_info
->x
))))
1082 target
= noce_emit_store_flag (if_info
,
1083 gen_reg_rtx (GET_MODE (if_info
->x
)),
1086 target
= expand_simple_binop (GET_MODE (if_info
->x
), AND
,
1088 target
, if_info
->x
, 0,
1093 if (target
!= if_info
->x
)
1094 noce_emit_move_insn (if_info
->x
, target
);
1096 seq
= end_ifcvt_sequence (if_info
);
1100 emit_insn_before_setloc (seq
, if_info
->jump
,
1101 INSN_LOCATOR (if_info
->insn_a
));
1111 /* Helper function for noce_try_cmove and noce_try_cmove_arith. */
1114 noce_emit_cmove (struct noce_if_info
*if_info
, rtx x
, enum rtx_code code
,
1115 rtx cmp_a
, rtx cmp_b
, rtx vfalse
, rtx vtrue
)
1117 /* If earliest == jump, try to build the cmove insn directly.
1118 This is helpful when combine has created some complex condition
1119 (like for alpha's cmovlbs) that we can't hope to regenerate
1120 through the normal interface. */
1122 if (if_info
->cond_earliest
== if_info
->jump
)
1126 tmp
= gen_rtx_fmt_ee (code
, GET_MODE (if_info
->cond
), cmp_a
, cmp_b
);
1127 tmp
= gen_rtx_IF_THEN_ELSE (GET_MODE (x
), tmp
, vtrue
, vfalse
);
1128 tmp
= gen_rtx_SET (VOIDmode
, x
, tmp
);
1131 tmp
= emit_insn (tmp
);
1133 if (recog_memoized (tmp
) >= 0)
1145 /* Don't even try if the comparison operands are weird. */
1146 if (! general_operand (cmp_a
, GET_MODE (cmp_a
))
1147 || ! general_operand (cmp_b
, GET_MODE (cmp_b
)))
1150 #if HAVE_conditional_move
1151 return emit_conditional_move (x
, code
, cmp_a
, cmp_b
, VOIDmode
,
1152 vtrue
, vfalse
, GET_MODE (x
),
1153 (code
== LTU
|| code
== GEU
1154 || code
== LEU
|| code
== GTU
));
1156 /* We'll never get here, as noce_process_if_block doesn't call the
1157 functions involved. Ifdef code, however, should be discouraged
1158 because it leads to typos in the code not selected. However,
1159 emit_conditional_move won't exist either. */
1164 /* Try only simple constants and registers here. More complex cases
1165 are handled in noce_try_cmove_arith after noce_try_store_flag_arith
1166 has had a go at it. */
1169 noce_try_cmove (struct noce_if_info
*if_info
)
1174 if ((CONSTANT_P (if_info
->a
) || register_operand (if_info
->a
, VOIDmode
))
1175 && (CONSTANT_P (if_info
->b
) || register_operand (if_info
->b
, VOIDmode
)))
1179 code
= GET_CODE (if_info
->cond
);
1180 target
= noce_emit_cmove (if_info
, if_info
->x
, code
,
1181 XEXP (if_info
->cond
, 0),
1182 XEXP (if_info
->cond
, 1),
1183 if_info
->a
, if_info
->b
);
1187 if (target
!= if_info
->x
)
1188 noce_emit_move_insn (if_info
->x
, target
);
1190 seq
= end_ifcvt_sequence (if_info
);
1194 emit_insn_before_setloc (seq
, if_info
->jump
,
1195 INSN_LOCATOR (if_info
->insn_a
));
1208 /* Try more complex cases involving conditional_move. */
1211 noce_try_cmove_arith (struct noce_if_info
*if_info
)
1221 /* A conditional move from two memory sources is equivalent to a
1222 conditional on their addresses followed by a load. Don't do this
1223 early because it'll screw alias analysis. Note that we've
1224 already checked for no side effects. */
1225 if (! no_new_pseudos
&& cse_not_expected
1226 && MEM_P (a
) && MEM_P (b
)
1227 && BRANCH_COST
>= 5)
1231 x
= gen_reg_rtx (Pmode
);
1235 /* ??? We could handle this if we knew that a load from A or B could
1236 not fault. This is also true if we've already loaded
1237 from the address along the path from ENTRY. */
1238 else if (may_trap_p (a
) || may_trap_p (b
))
1241 /* if (test) x = a + b; else x = c - d;
1248 code
= GET_CODE (if_info
->cond
);
1249 insn_a
= if_info
->insn_a
;
1250 insn_b
= if_info
->insn_b
;
1252 /* Possibly rearrange operands to make things come out more natural. */
1253 if (reversed_comparison_code (if_info
->cond
, if_info
->jump
) != UNKNOWN
)
1256 if (rtx_equal_p (b
, x
))
1258 else if (general_operand (b
, GET_MODE (b
)))
1263 code
= reversed_comparison_code (if_info
->cond
, if_info
->jump
);
1264 tmp
= a
, a
= b
, b
= tmp
;
1265 tmp
= insn_a
, insn_a
= insn_b
, insn_b
= tmp
;
1271 /* If either operand is complex, load it into a register first.
1272 The best way to do this is to copy the original insn. In this
1273 way we preserve any clobbers etc that the insn may have had.
1274 This is of course not possible in the IS_MEM case. */
1275 if (! general_operand (a
, GET_MODE (a
)))
1280 goto end_seq_and_fail
;
1284 tmp
= gen_reg_rtx (GET_MODE (a
));
1285 tmp
= emit_insn (gen_rtx_SET (VOIDmode
, tmp
, a
));
1288 goto end_seq_and_fail
;
1291 a
= gen_reg_rtx (GET_MODE (a
));
1292 tmp
= copy_rtx (insn_a
);
1293 set
= single_set (tmp
);
1295 tmp
= emit_insn (PATTERN (tmp
));
1297 if (recog_memoized (tmp
) < 0)
1298 goto end_seq_and_fail
;
1300 if (! general_operand (b
, GET_MODE (b
)))
1305 goto end_seq_and_fail
;
1309 tmp
= gen_reg_rtx (GET_MODE (b
));
1310 tmp
= emit_insn (gen_rtx_SET (VOIDmode
,
1315 goto end_seq_and_fail
;
1318 b
= gen_reg_rtx (GET_MODE (b
));
1319 tmp
= copy_rtx (insn_b
);
1320 set
= single_set (tmp
);
1322 tmp
= emit_insn (PATTERN (tmp
));
1324 if (recog_memoized (tmp
) < 0)
1325 goto end_seq_and_fail
;
1328 target
= noce_emit_cmove (if_info
, x
, code
, XEXP (if_info
->cond
, 0),
1329 XEXP (if_info
->cond
, 1), a
, b
);
1332 goto end_seq_and_fail
;
1334 /* If we're handling a memory for above, emit the load now. */
1337 tmp
= gen_rtx_MEM (GET_MODE (if_info
->x
), target
);
1339 /* Copy over flags as appropriate. */
1340 if (MEM_VOLATILE_P (if_info
->a
) || MEM_VOLATILE_P (if_info
->b
))
1341 MEM_VOLATILE_P (tmp
) = 1;
1342 if (MEM_IN_STRUCT_P (if_info
->a
) && MEM_IN_STRUCT_P (if_info
->b
))
1343 MEM_IN_STRUCT_P (tmp
) = 1;
1344 if (MEM_SCALAR_P (if_info
->a
) && MEM_SCALAR_P (if_info
->b
))
1345 MEM_SCALAR_P (tmp
) = 1;
1346 if (MEM_ALIAS_SET (if_info
->a
) == MEM_ALIAS_SET (if_info
->b
))
1347 set_mem_alias_set (tmp
, MEM_ALIAS_SET (if_info
->a
));
1349 MIN (MEM_ALIGN (if_info
->a
), MEM_ALIGN (if_info
->b
)));
1351 noce_emit_move_insn (if_info
->x
, tmp
);
1353 else if (target
!= x
)
1354 noce_emit_move_insn (x
, target
);
1356 tmp
= end_ifcvt_sequence (if_info
);
1360 emit_insn_before_setloc (tmp
, if_info
->jump
, INSN_LOCATOR (if_info
->insn_a
));
1368 /* For most cases, the simplified condition we found is the best
1369 choice, but this is not the case for the min/max/abs transforms.
1370 For these we wish to know that it is A or B in the condition. */
1373 noce_get_alt_condition (struct noce_if_info
*if_info
, rtx target
,
1376 rtx cond
, set
, insn
;
1379 /* If target is already mentioned in the known condition, return it. */
1380 if (reg_mentioned_p (target
, if_info
->cond
))
1382 *earliest
= if_info
->cond_earliest
;
1383 return if_info
->cond
;
1386 set
= pc_set (if_info
->jump
);
1387 cond
= XEXP (SET_SRC (set
), 0);
1389 = GET_CODE (XEXP (SET_SRC (set
), 2)) == LABEL_REF
1390 && XEXP (XEXP (SET_SRC (set
), 2), 0) == JUMP_LABEL (if_info
->jump
);
1392 /* If we're looking for a constant, try to make the conditional
1393 have that constant in it. There are two reasons why it may
1394 not have the constant we want:
1396 1. GCC may have needed to put the constant in a register, because
1397 the target can't compare directly against that constant. For
1398 this case, we look for a SET immediately before the comparison
1399 that puts a constant in that register.
1401 2. GCC may have canonicalized the conditional, for example
1402 replacing "if x < 4" with "if x <= 3". We can undo that (or
1403 make equivalent types of changes) to get the constants we need
1404 if they're off by one in the right direction. */
1406 if (GET_CODE (target
) == CONST_INT
)
1408 enum rtx_code code
= GET_CODE (if_info
->cond
);
1409 rtx op_a
= XEXP (if_info
->cond
, 0);
1410 rtx op_b
= XEXP (if_info
->cond
, 1);
1413 /* First, look to see if we put a constant in a register. */
1414 prev_insn
= PREV_INSN (if_info
->cond_earliest
);
1416 && INSN_P (prev_insn
)
1417 && GET_CODE (PATTERN (prev_insn
)) == SET
)
1419 rtx src
= find_reg_equal_equiv_note (prev_insn
);
1421 src
= SET_SRC (PATTERN (prev_insn
));
1422 if (GET_CODE (src
) == CONST_INT
)
1424 if (rtx_equal_p (op_a
, SET_DEST (PATTERN (prev_insn
))))
1426 else if (rtx_equal_p (op_b
, SET_DEST (PATTERN (prev_insn
))))
1429 if (GET_CODE (op_a
) == CONST_INT
)
1434 code
= swap_condition (code
);
1439 /* Now, look to see if we can get the right constant by
1440 adjusting the conditional. */
1441 if (GET_CODE (op_b
) == CONST_INT
)
1443 HOST_WIDE_INT desired_val
= INTVAL (target
);
1444 HOST_WIDE_INT actual_val
= INTVAL (op_b
);
1449 if (actual_val
== desired_val
+ 1)
1452 op_b
= GEN_INT (desired_val
);
1456 if (actual_val
== desired_val
- 1)
1459 op_b
= GEN_INT (desired_val
);
1463 if (actual_val
== desired_val
- 1)
1466 op_b
= GEN_INT (desired_val
);
1470 if (actual_val
== desired_val
+ 1)
1473 op_b
= GEN_INT (desired_val
);
1481 /* If we made any changes, generate a new conditional that is
1482 equivalent to what we started with, but has the right
1484 if (code
!= GET_CODE (if_info
->cond
)
1485 || op_a
!= XEXP (if_info
->cond
, 0)
1486 || op_b
!= XEXP (if_info
->cond
, 1))
1488 cond
= gen_rtx_fmt_ee (code
, GET_MODE (cond
), op_a
, op_b
);
1489 *earliest
= if_info
->cond_earliest
;
1494 cond
= canonicalize_condition (if_info
->jump
, cond
, reverse
,
1495 earliest
, target
, false, true);
1496 if (! cond
|| ! reg_mentioned_p (target
, cond
))
1499 /* We almost certainly searched back to a different place.
1500 Need to re-verify correct lifetimes. */
1502 /* X may not be mentioned in the range (cond_earliest, jump]. */
1503 for (insn
= if_info
->jump
; insn
!= *earliest
; insn
= PREV_INSN (insn
))
1504 if (INSN_P (insn
) && reg_overlap_mentioned_p (if_info
->x
, PATTERN (insn
)))
1507 /* A and B may not be modified in the range [cond_earliest, jump). */
1508 for (insn
= *earliest
; insn
!= if_info
->jump
; insn
= NEXT_INSN (insn
))
1510 && (modified_in_p (if_info
->a
, insn
)
1511 || modified_in_p (if_info
->b
, insn
)))
1517 /* Convert "if (a < b) x = a; else x = b;" to "x = min(a, b);", etc. */
1520 noce_try_minmax (struct noce_if_info
*if_info
)
1522 rtx cond
, earliest
, target
, seq
;
1523 enum rtx_code code
, op
;
1526 /* ??? Can't guarantee that expand_binop won't create pseudos. */
1530 /* ??? Reject modes with NaNs or signed zeros since we don't know how
1531 they will be resolved with an SMIN/SMAX. It wouldn't be too hard
1532 to get the target to tell us... */
1533 if (HONOR_SIGNED_ZEROS (GET_MODE (if_info
->x
))
1534 || HONOR_NANS (GET_MODE (if_info
->x
)))
1537 cond
= noce_get_alt_condition (if_info
, if_info
->a
, &earliest
);
1541 /* Verify the condition is of the form we expect, and canonicalize
1542 the comparison code. */
1543 code
= GET_CODE (cond
);
1544 if (rtx_equal_p (XEXP (cond
, 0), if_info
->a
))
1546 if (! rtx_equal_p (XEXP (cond
, 1), if_info
->b
))
1549 else if (rtx_equal_p (XEXP (cond
, 1), if_info
->a
))
1551 if (! rtx_equal_p (XEXP (cond
, 0), if_info
->b
))
1553 code
= swap_condition (code
);
1558 /* Determine what sort of operation this is. Note that the code is for
1559 a taken branch, so the code->operation mapping appears backwards. */
1592 target
= expand_simple_binop (GET_MODE (if_info
->x
), op
,
1593 if_info
->a
, if_info
->b
,
1594 if_info
->x
, unsignedp
, OPTAB_WIDEN
);
1600 if (target
!= if_info
->x
)
1601 noce_emit_move_insn (if_info
->x
, target
);
1603 seq
= end_ifcvt_sequence (if_info
);
1607 emit_insn_before_setloc (seq
, if_info
->jump
, INSN_LOCATOR (if_info
->insn_a
));
1608 if_info
->cond
= cond
;
1609 if_info
->cond_earliest
= earliest
;
1614 /* Convert "if (a < 0) x = -a; else x = a;" to "x = abs(a);", etc. */
1617 noce_try_abs (struct noce_if_info
*if_info
)
1619 rtx cond
, earliest
, target
, seq
, a
, b
, c
;
1622 /* ??? Can't guarantee that expand_binop won't create pseudos. */
1626 /* Recognize A and B as constituting an ABS or NABS. */
1629 if (GET_CODE (a
) == NEG
&& rtx_equal_p (XEXP (a
, 0), b
))
1631 else if (GET_CODE (b
) == NEG
&& rtx_equal_p (XEXP (b
, 0), a
))
1633 c
= a
; a
= b
; b
= c
;
1639 cond
= noce_get_alt_condition (if_info
, b
, &earliest
);
1643 /* Verify the condition is of the form we expect. */
1644 if (rtx_equal_p (XEXP (cond
, 0), b
))
1646 else if (rtx_equal_p (XEXP (cond
, 1), b
))
1651 /* Verify that C is zero. Search backward through the block for
1652 a REG_EQUAL note if necessary. */
1655 rtx insn
, note
= NULL
;
1656 for (insn
= earliest
;
1657 insn
!= BB_HEAD (if_info
->test_bb
);
1658 insn
= PREV_INSN (insn
))
1660 && ((note
= find_reg_note (insn
, REG_EQUAL
, c
))
1661 || (note
= find_reg_note (insn
, REG_EQUIV
, c
))))
1668 && GET_CODE (XEXP (c
, 0)) == SYMBOL_REF
1669 && CONSTANT_POOL_ADDRESS_P (XEXP (c
, 0)))
1670 c
= get_pool_constant (XEXP (c
, 0));
1672 /* Work around funny ideas get_condition has wrt canonicalization.
1673 Note that these rtx constants are known to be CONST_INT, and
1674 therefore imply integer comparisons. */
1675 if (c
== constm1_rtx
&& GET_CODE (cond
) == GT
)
1677 else if (c
== const1_rtx
&& GET_CODE (cond
) == LT
)
1679 else if (c
!= CONST0_RTX (GET_MODE (b
)))
1682 /* Determine what sort of operation this is. */
1683 switch (GET_CODE (cond
))
1702 target
= expand_abs_nojump (GET_MODE (if_info
->x
), b
, if_info
->x
, 1);
1704 /* ??? It's a quandary whether cmove would be better here, especially
1705 for integers. Perhaps combine will clean things up. */
1706 if (target
&& negate
)
1707 target
= expand_simple_unop (GET_MODE (target
), NEG
, target
, if_info
->x
, 0);
1715 if (target
!= if_info
->x
)
1716 noce_emit_move_insn (if_info
->x
, target
);
1718 seq
= end_ifcvt_sequence (if_info
);
1722 emit_insn_before_setloc (seq
, if_info
->jump
, INSN_LOCATOR (if_info
->insn_a
));
1723 if_info
->cond
= cond
;
1724 if_info
->cond_earliest
= earliest
;
1729 /* Convert "if (m < 0) x = b; else x = 0;" to "x = (m >> C) & b;". */
1732 noce_try_sign_mask (struct noce_if_info
*if_info
)
1734 rtx cond
, t
, m
, c
, seq
;
1735 enum machine_mode mode
;
1741 cond
= if_info
->cond
;
1742 code
= GET_CODE (cond
);
1747 if (if_info
->a
== const0_rtx
)
1749 if ((code
== LT
&& c
== const0_rtx
)
1750 || (code
== LE
&& c
== constm1_rtx
))
1753 else if (if_info
->b
== const0_rtx
)
1755 if ((code
== GE
&& c
== const0_rtx
)
1756 || (code
== GT
&& c
== constm1_rtx
))
1760 if (! t
|| side_effects_p (t
))
1763 /* We currently don't handle different modes. */
1764 mode
= GET_MODE (t
);
1765 if (GET_MODE (m
) != mode
)
1768 /* This is only profitable if T is cheap, or T is unconditionally
1769 executed/evaluated in the original insn sequence. */
1770 if (rtx_cost (t
, SET
) >= COSTS_N_INSNS (2)
1771 && (!if_info
->b_unconditional
1772 || t
!= if_info
->b
))
1776 /* Use emit_store_flag to generate "m < 0 ? -1 : 0" instead of expanding
1777 "(signed) m >> 31" directly. This benefits targets with specialized
1778 insns to obtain the signmask, but still uses ashr_optab otherwise. */
1779 m
= emit_store_flag (gen_reg_rtx (mode
), LT
, m
, const0_rtx
, mode
, 0, -1);
1780 t
= m
? expand_binop (mode
, and_optab
, m
, t
, NULL_RTX
, 0, OPTAB_DIRECT
)
1789 noce_emit_move_insn (if_info
->x
, t
);
1791 seq
= end_ifcvt_sequence (if_info
);
1795 emit_insn_before_setloc (seq
, if_info
->jump
, INSN_LOCATOR (if_info
->insn_a
));
1800 /* Similar to get_condition, only the resulting condition must be
1801 valid at JUMP, instead of at EARLIEST. */
1804 noce_get_condition (rtx jump
, rtx
*earliest
)
1809 if (! any_condjump_p (jump
))
1812 set
= pc_set (jump
);
1814 /* If this branches to JUMP_LABEL when the condition is false,
1815 reverse the condition. */
1816 reverse
= (GET_CODE (XEXP (SET_SRC (set
), 2)) == LABEL_REF
1817 && XEXP (XEXP (SET_SRC (set
), 2), 0) == JUMP_LABEL (jump
));
1819 /* If the condition variable is a register and is MODE_INT, accept it. */
1821 cond
= XEXP (SET_SRC (set
), 0);
1822 tmp
= XEXP (cond
, 0);
1823 if (REG_P (tmp
) && GET_MODE_CLASS (GET_MODE (tmp
)) == MODE_INT
)
1828 cond
= gen_rtx_fmt_ee (reverse_condition (GET_CODE (cond
)),
1829 GET_MODE (cond
), tmp
, XEXP (cond
, 1));
1833 /* Otherwise, fall back on canonicalize_condition to do the dirty
1834 work of manipulating MODE_CC values and COMPARE rtx codes. */
1835 return canonicalize_condition (jump
, cond
, reverse
, earliest
,
1836 NULL_RTX
, false, true);
1839 /* Return true if OP is ok for if-then-else processing. */
1842 noce_operand_ok (rtx op
)
1844 /* We special-case memories, so handle any of them with
1845 no address side effects. */
1847 return ! side_effects_p (XEXP (op
, 0));
1849 if (side_effects_p (op
))
1852 return ! may_trap_p (op
);
1855 /* Given a simple IF-THEN or IF-THEN-ELSE block, attempt to convert it
1856 without using conditional execution. Return TRUE if we were
1857 successful at converting the block. */
1860 noce_process_if_block (struct ce_if_block
* ce_info
)
1862 basic_block test_bb
= ce_info
->test_bb
; /* test block */
1863 basic_block then_bb
= ce_info
->then_bb
; /* THEN */
1864 basic_block else_bb
= ce_info
->else_bb
; /* ELSE or NULL */
1865 struct noce_if_info if_info
;
1868 rtx orig_x
, x
, a
, b
;
1871 /* We're looking for patterns of the form
1873 (1) if (...) x = a; else x = b;
1874 (2) x = b; if (...) x = a;
1875 (3) if (...) x = a; // as if with an initial x = x.
1877 The later patterns require jumps to be more expensive.
1879 ??? For future expansion, look for multiple X in such patterns. */
1881 /* If test is comprised of && or || elements, don't handle it unless it is
1882 the special case of && elements without an ELSE block. */
1883 if (ce_info
->num_multiple_test_blocks
)
1885 if (else_bb
|| ! ce_info
->and_and_p
)
1888 ce_info
->test_bb
= test_bb
= ce_info
->last_test_bb
;
1889 ce_info
->num_multiple_test_blocks
= 0;
1890 ce_info
->num_and_and_blocks
= 0;
1891 ce_info
->num_or_or_blocks
= 0;
1894 /* If this is not a standard conditional jump, we can't parse it. */
1895 jump
= BB_END (test_bb
);
1896 cond
= noce_get_condition (jump
, &if_info
.cond_earliest
);
1900 /* If the conditional jump is more than just a conditional
1901 jump, then we can not do if-conversion on this block. */
1902 if (! onlyjump_p (jump
))
1905 /* We must be comparing objects whose modes imply the size. */
1906 if (GET_MODE (XEXP (cond
, 0)) == BLKmode
)
1909 /* Look for one of the potential sets. */
1910 insn_a
= first_active_insn (then_bb
);
1912 || insn_a
!= last_active_insn (then_bb
, FALSE
)
1913 || (set_a
= single_set (insn_a
)) == NULL_RTX
)
1916 x
= SET_DEST (set_a
);
1917 a
= SET_SRC (set_a
);
1919 /* Look for the other potential set. Make sure we've got equivalent
1921 /* ??? This is overconservative. Storing to two different mems is
1922 as easy as conditionally computing the address. Storing to a
1923 single mem merely requires a scratch memory to use as one of the
1924 destination addresses; often the memory immediately below the
1925 stack pointer is available for this. */
1929 insn_b
= first_active_insn (else_bb
);
1931 || insn_b
!= last_active_insn (else_bb
, FALSE
)
1932 || (set_b
= single_set (insn_b
)) == NULL_RTX
1933 || ! rtx_equal_p (x
, SET_DEST (set_b
)))
1938 insn_b
= prev_nonnote_insn (if_info
.cond_earliest
);
1939 /* We're going to be moving the evaluation of B down from above
1940 COND_EARLIEST to JUMP. Make sure the relevant data is still
1943 || !NONJUMP_INSN_P (insn_b
)
1944 || (set_b
= single_set (insn_b
)) == NULL_RTX
1945 || ! rtx_equal_p (x
, SET_DEST (set_b
))
1946 || reg_overlap_mentioned_p (x
, SET_SRC (set_b
))
1947 || modified_between_p (SET_SRC (set_b
),
1948 PREV_INSN (if_info
.cond_earliest
), jump
)
1949 /* Likewise with X. In particular this can happen when
1950 noce_get_condition looks farther back in the instruction
1951 stream than one might expect. */
1952 || reg_overlap_mentioned_p (x
, cond
)
1953 || reg_overlap_mentioned_p (x
, a
)
1954 || modified_between_p (x
, PREV_INSN (if_info
.cond_earliest
), jump
))
1955 insn_b
= set_b
= NULL_RTX
;
1958 /* If x has side effects then only the if-then-else form is safe to
1959 convert. But even in that case we would need to restore any notes
1960 (such as REG_INC) at then end. That can be tricky if
1961 noce_emit_move_insn expands to more than one insn, so disable the
1962 optimization entirely for now if there are side effects. */
1963 if (side_effects_p (x
))
1966 b
= (set_b
? SET_SRC (set_b
) : x
);
1968 /* Only operate on register destinations, and even then avoid extending
1969 the lifetime of hard registers on small register class machines. */
1972 || (SMALL_REGISTER_CLASSES
1973 && REGNO (x
) < FIRST_PSEUDO_REGISTER
))
1975 if (no_new_pseudos
|| GET_MODE (x
) == BLKmode
)
1977 x
= gen_reg_rtx (GET_MODE (GET_CODE (x
) == STRICT_LOW_PART
1978 ? XEXP (x
, 0) : x
));
1981 /* Don't operate on sources that may trap or are volatile. */
1982 if (! noce_operand_ok (a
) || ! noce_operand_ok (b
))
1985 /* Set up the info block for our subroutines. */
1986 if_info
.test_bb
= test_bb
;
1987 if_info
.cond
= cond
;
1988 if_info
.jump
= jump
;
1989 if_info
.insn_a
= insn_a
;
1990 if_info
.insn_b
= insn_b
;
1994 if_info
.b_unconditional
= else_bb
== 0;
1996 /* Try optimizations in some approximation of a useful order. */
1997 /* ??? Should first look to see if X is live incoming at all. If it
1998 isn't, we don't need anything but an unconditional set. */
2000 /* Look and see if A and B are really the same. Avoid creating silly
2001 cmove constructs that no one will fix up later. */
2002 if (rtx_equal_p (a
, b
))
2004 /* If we have an INSN_B, we don't have to create any new rtl. Just
2005 move the instruction that we already have. If we don't have an
2006 INSN_B, that means that A == X, and we've got a noop move. In
2007 that case don't do anything and let the code below delete INSN_A. */
2008 if (insn_b
&& else_bb
)
2012 if (else_bb
&& insn_b
== BB_END (else_bb
))
2013 BB_END (else_bb
) = PREV_INSN (insn_b
);
2014 reorder_insns (insn_b
, insn_b
, PREV_INSN (jump
));
2016 /* If there was a REG_EQUAL note, delete it since it may have been
2017 true due to this insn being after a jump. */
2018 if ((note
= find_reg_note (insn_b
, REG_EQUAL
, NULL_RTX
)) != 0)
2019 remove_note (insn_b
, note
);
2023 /* If we have "x = b; if (...) x = a;", and x has side-effects, then
2024 x must be executed twice. */
2025 else if (insn_b
&& side_effects_p (orig_x
))
2032 /* Disallow the "if (...) x = a;" form (with an implicit "else x = x;")
2033 for most optimizations if writing to x may trap, i.e. it's a memory
2034 other than a static var or a stack slot. */
2037 && ! MEM_NOTRAP_P (orig_x
)
2038 && rtx_addr_can_trap_p (XEXP (orig_x
, 0)))
2040 if (HAVE_conditional_move
)
2042 if (noce_try_cmove (&if_info
))
2044 if (! HAVE_conditional_execution
2045 && noce_try_cmove_arith (&if_info
))
2051 if (noce_try_move (&if_info
))
2053 if (noce_try_store_flag (&if_info
))
2055 if (noce_try_minmax (&if_info
))
2057 if (noce_try_abs (&if_info
))
2059 if (HAVE_conditional_move
2060 && noce_try_cmove (&if_info
))
2062 if (! HAVE_conditional_execution
)
2064 if (noce_try_store_flag_constants (&if_info
))
2066 if (noce_try_addcc (&if_info
))
2068 if (noce_try_store_flag_mask (&if_info
))
2070 if (HAVE_conditional_move
2071 && noce_try_cmove_arith (&if_info
))
2073 if (noce_try_sign_mask (&if_info
))
2080 /* The original sets may now be killed. */
2081 delete_insn (insn_a
);
2083 /* Several special cases here: First, we may have reused insn_b above,
2084 in which case insn_b is now NULL. Second, we want to delete insn_b
2085 if it came from the ELSE block, because follows the now correct
2086 write that appears in the TEST block. However, if we got insn_b from
2087 the TEST block, it may in fact be loading data needed for the comparison.
2088 We'll let life_analysis remove the insn if it's really dead. */
2089 if (insn_b
&& else_bb
)
2090 delete_insn (insn_b
);
2092 /* The new insns will have been inserted immediately before the jump. We
2093 should be able to remove the jump with impunity, but the condition itself
2094 may have been modified by gcse to be shared across basic blocks. */
2097 /* If we used a temporary, fix it up now. */
2101 noce_emit_move_insn (orig_x
, x
);
2102 insn_b
= get_insns ();
2103 set_used_flags (orig_x
);
2104 unshare_all_rtl_in_chain (insn_b
);
2107 emit_insn_after_setloc (insn_b
, BB_END (test_bb
), INSN_LOCATOR (insn_a
));
2110 /* Merge the blocks! */
2111 merge_if_block (ce_info
);
2116 /* Attempt to convert an IF-THEN or IF-THEN-ELSE block into
2117 straight line code. Return true if successful. */
2120 process_if_block (struct ce_if_block
* ce_info
)
2122 if (! reload_completed
2123 && noce_process_if_block (ce_info
))
2126 if (HAVE_conditional_execution
&& reload_completed
)
2128 /* If we have && and || tests, try to first handle combining the && and
2129 || tests into the conditional code, and if that fails, go back and
2130 handle it without the && and ||, which at present handles the && case
2131 if there was no ELSE block. */
2132 if (cond_exec_process_if_block (ce_info
, TRUE
))
2135 if (ce_info
->num_multiple_test_blocks
)
2139 if (cond_exec_process_if_block (ce_info
, FALSE
))
2147 /* Merge the blocks and mark for local life update. */
2150 merge_if_block (struct ce_if_block
* ce_info
)
2152 basic_block test_bb
= ce_info
->test_bb
; /* last test block */
2153 basic_block then_bb
= ce_info
->then_bb
; /* THEN */
2154 basic_block else_bb
= ce_info
->else_bb
; /* ELSE or NULL */
2155 basic_block join_bb
= ce_info
->join_bb
; /* join block */
2156 basic_block combo_bb
;
2158 /* All block merging is done into the lower block numbers. */
2162 /* Merge any basic blocks to handle && and || subtests. Each of
2163 the blocks are on the fallthru path from the predecessor block. */
2164 if (ce_info
->num_multiple_test_blocks
> 0)
2166 basic_block bb
= test_bb
;
2167 basic_block last_test_bb
= ce_info
->last_test_bb
;
2168 basic_block fallthru
= block_fallthru (bb
);
2173 fallthru
= block_fallthru (bb
);
2174 merge_blocks (combo_bb
, bb
);
2177 while (bb
!= last_test_bb
);
2180 /* Merge TEST block into THEN block. Normally the THEN block won't have a
2181 label, but it might if there were || tests. That label's count should be
2182 zero, and it normally should be removed. */
2186 if (combo_bb
->global_live_at_end
)
2187 COPY_REG_SET (combo_bb
->global_live_at_end
,
2188 then_bb
->global_live_at_end
);
2189 merge_blocks (combo_bb
, then_bb
);
2193 /* The ELSE block, if it existed, had a label. That label count
2194 will almost always be zero, but odd things can happen when labels
2195 get their addresses taken. */
2198 merge_blocks (combo_bb
, else_bb
);
2202 /* If there was no join block reported, that means it was not adjacent
2203 to the others, and so we cannot merge them. */
2207 rtx last
= BB_END (combo_bb
);
2209 /* The outgoing edge for the current COMBO block should already
2210 be correct. Verify this. */
2211 if (EDGE_COUNT (combo_bb
->succs
) == 0)
2213 if (find_reg_note (last
, REG_NORETURN
, NULL
))
2215 else if (NONJUMP_INSN_P (last
)
2216 && GET_CODE (PATTERN (last
)) == TRAP_IF
2217 && TRAP_CONDITION (PATTERN (last
)) == const_true_rtx
)
2223 /* There should still be something at the end of the THEN or ELSE
2224 blocks taking us to our final destination. */
2225 else if (JUMP_P (last
))
2227 else if (EDGE_SUCC (combo_bb
, 0)->dest
== EXIT_BLOCK_PTR
2229 && SIBLING_CALL_P (last
))
2231 else if ((EDGE_SUCC (combo_bb
, 0)->flags
& EDGE_EH
)
2232 && can_throw_internal (last
))
2238 /* The JOIN block may have had quite a number of other predecessors too.
2239 Since we've already merged the TEST, THEN and ELSE blocks, we should
2240 have only one remaining edge from our if-then-else diamond. If there
2241 is more than one remaining edge, it must come from elsewhere. There
2242 may be zero incoming edges if the THEN block didn't actually join
2243 back up (as with a call to abort). */
2244 else if (EDGE_COUNT (join_bb
->preds
) < 2
2245 && join_bb
!= EXIT_BLOCK_PTR
)
2247 /* We can merge the JOIN. */
2248 if (combo_bb
->global_live_at_end
)
2249 COPY_REG_SET (combo_bb
->global_live_at_end
,
2250 join_bb
->global_live_at_end
);
2252 merge_blocks (combo_bb
, join_bb
);
2257 /* We cannot merge the JOIN. */
2259 /* The outgoing edge for the current COMBO block should already
2260 be correct. Verify this. */
2261 if (EDGE_COUNT (combo_bb
->succs
) > 1
2262 || EDGE_SUCC (combo_bb
, 0)->dest
!= join_bb
)
2265 /* Remove the jump and cruft from the end of the COMBO block. */
2266 if (join_bb
!= EXIT_BLOCK_PTR
)
2267 tidy_fallthru_edge (EDGE_SUCC (combo_bb
, 0));
2270 num_updated_if_blocks
++;
2273 /* Find a block ending in a simple IF condition and try to transform it
2274 in some way. When converting a multi-block condition, put the new code
2275 in the first such block and delete the rest. Return a pointer to this
2276 first block if some transformation was done. Return NULL otherwise. */
2279 find_if_header (basic_block test_bb
, int pass
)
2281 ce_if_block_t ce_info
;
2285 /* The kind of block we're looking for has exactly two successors. */
2286 if (EDGE_COUNT (test_bb
->succs
) != 2)
2289 then_edge
= EDGE_SUCC (test_bb
, 0);
2290 else_edge
= EDGE_SUCC (test_bb
, 1);
2292 /* Neither edge should be abnormal. */
2293 if ((then_edge
->flags
& EDGE_COMPLEX
)
2294 || (else_edge
->flags
& EDGE_COMPLEX
))
2297 /* Nor exit the loop. */
2298 if ((then_edge
->flags
& EDGE_LOOP_EXIT
)
2299 || (else_edge
->flags
& EDGE_LOOP_EXIT
))
2302 /* The THEN edge is canonically the one that falls through. */
2303 if (then_edge
->flags
& EDGE_FALLTHRU
)
2305 else if (else_edge
->flags
& EDGE_FALLTHRU
)
2308 else_edge
= then_edge
;
2312 /* Otherwise this must be a multiway branch of some sort. */
2315 memset (&ce_info
, '\0', sizeof (ce_info
));
2316 ce_info
.test_bb
= test_bb
;
2317 ce_info
.then_bb
= then_edge
->dest
;
2318 ce_info
.else_bb
= else_edge
->dest
;
2319 ce_info
.pass
= pass
;
2321 #ifdef IFCVT_INIT_EXTRA_FIELDS
2322 IFCVT_INIT_EXTRA_FIELDS (&ce_info
);
2325 if (find_if_block (&ce_info
))
2328 if (HAVE_trap
&& HAVE_conditional_trap
2329 && find_cond_trap (test_bb
, then_edge
, else_edge
))
2332 if (dom_computed
[CDI_POST_DOMINATORS
] >= DOM_NO_FAST_QUERY
2333 && (! HAVE_conditional_execution
|| reload_completed
))
2335 if (find_if_case_1 (test_bb
, then_edge
, else_edge
))
2337 if (find_if_case_2 (test_bb
, then_edge
, else_edge
))
2345 fprintf (dump_file
, "Conversion succeeded on pass %d.\n", pass
);
2346 return ce_info
.test_bb
;
2349 /* Return true if a block has two edges, one of which falls through to the next
2350 block, and the other jumps to a specific block, so that we can tell if the
2351 block is part of an && test or an || test. Returns either -1 or the number
2352 of non-note, non-jump, non-USE/CLOBBER insns in the block. */
2355 block_jumps_and_fallthru_p (basic_block cur_bb
, basic_block target_bb
)
2358 int fallthru_p
= FALSE
;
2364 if (!cur_bb
|| !target_bb
)
2367 /* If no edges, obviously it doesn't jump or fallthru. */
2368 if (EDGE_COUNT (cur_bb
->succs
) == 0)
2371 FOR_EACH_EDGE (cur_edge
, cur_bb
->succs
)
2373 if (cur_edge
->flags
& EDGE_COMPLEX
)
2374 /* Anything complex isn't what we want. */
2377 else if (cur_edge
->flags
& EDGE_FALLTHRU
)
2380 else if (cur_edge
->dest
== target_bb
)
2388 if ((jump_p
& fallthru_p
) == 0)
2391 /* Don't allow calls in the block, since this is used to group && and ||
2392 together for conditional execution support. ??? we should support
2393 conditional execution support across calls for IA-64 some day, but
2394 for now it makes the code simpler. */
2395 end
= BB_END (cur_bb
);
2396 insn
= BB_HEAD (cur_bb
);
2398 while (insn
!= NULL_RTX
)
2405 && GET_CODE (PATTERN (insn
)) != USE
2406 && GET_CODE (PATTERN (insn
)) != CLOBBER
)
2412 insn
= NEXT_INSN (insn
);
2418 /* Determine if a given basic block heads a simple IF-THEN or IF-THEN-ELSE
2419 block. If so, we'll try to convert the insns to not require the branch.
2420 Return TRUE if we were successful at converting the block. */
2423 find_if_block (struct ce_if_block
* ce_info
)
2425 basic_block test_bb
= ce_info
->test_bb
;
2426 basic_block then_bb
= ce_info
->then_bb
;
2427 basic_block else_bb
= ce_info
->else_bb
;
2428 basic_block join_bb
= NULL_BLOCK
;
2429 int then_predecessors
;
2430 int else_predecessors
;
2434 ce_info
->last_test_bb
= test_bb
;
2436 /* Discover if any fall through predecessors of the current test basic block
2437 were && tests (which jump to the else block) or || tests (which jump to
2439 if (HAVE_conditional_execution
&& reload_completed
2440 && EDGE_COUNT (test_bb
->preds
) == 1
2441 && EDGE_PRED (test_bb
, 0)->flags
== EDGE_FALLTHRU
)
2443 basic_block bb
= EDGE_PRED (test_bb
, 0)->src
;
2444 basic_block target_bb
;
2445 int max_insns
= MAX_CONDITIONAL_EXECUTE
;
2448 /* Determine if the preceding block is an && or || block. */
2449 if ((n_insns
= block_jumps_and_fallthru_p (bb
, else_bb
)) >= 0)
2451 ce_info
->and_and_p
= TRUE
;
2452 target_bb
= else_bb
;
2454 else if ((n_insns
= block_jumps_and_fallthru_p (bb
, then_bb
)) >= 0)
2456 ce_info
->and_and_p
= FALSE
;
2457 target_bb
= then_bb
;
2460 target_bb
= NULL_BLOCK
;
2462 if (target_bb
&& n_insns
<= max_insns
)
2464 int total_insns
= 0;
2467 ce_info
->last_test_bb
= test_bb
;
2469 /* Found at least one && or || block, look for more. */
2472 ce_info
->test_bb
= test_bb
= bb
;
2473 total_insns
+= n_insns
;
2476 if (EDGE_COUNT (bb
->preds
) != 1)
2479 bb
= EDGE_PRED (bb
, 0)->src
;
2480 n_insns
= block_jumps_and_fallthru_p (bb
, target_bb
);
2482 while (n_insns
>= 0 && (total_insns
+ n_insns
) <= max_insns
);
2484 ce_info
->num_multiple_test_blocks
= blocks
;
2485 ce_info
->num_multiple_test_insns
= total_insns
;
2487 if (ce_info
->and_and_p
)
2488 ce_info
->num_and_and_blocks
= blocks
;
2490 ce_info
->num_or_or_blocks
= blocks
;
2494 /* Count the number of edges the THEN and ELSE blocks have. */
2495 then_predecessors
= 0;
2496 FOR_EACH_EDGE (cur_edge
, then_bb
->preds
)
2498 then_predecessors
++;
2499 if (cur_edge
->flags
& EDGE_COMPLEX
)
2504 else_predecessors
= 0;
2505 FOR_EACH_EDGE (cur_edge
, else_bb
->preds
)
2507 else_predecessors
++;
2508 if (cur_edge
->flags
& EDGE_COMPLEX
)
2513 /* The THEN block of an IF-THEN combo must have exactly one predecessor,
2514 other than any || blocks which jump to the THEN block. */
2515 if ((then_predecessors
- ce_info
->num_or_or_blocks
) != 1)
2518 /* The THEN block of an IF-THEN combo must have zero or one successors. */
2519 if (EDGE_COUNT (then_bb
->succs
) > 0
2520 && (EDGE_COUNT (then_bb
->succs
) > 1
2521 || (EDGE_SUCC (then_bb
, 0)->flags
& EDGE_COMPLEX
)
2522 || (flow2_completed
&& tablejump_p (BB_END (then_bb
), NULL
, NULL
))))
2525 /* If the THEN block has no successors, conditional execution can still
2526 make a conditional call. Don't do this unless the ELSE block has
2527 only one incoming edge -- the CFG manipulation is too ugly otherwise.
2528 Check for the last insn of the THEN block being an indirect jump, which
2529 is listed as not having any successors, but confuses the rest of the CE
2530 code processing. ??? we should fix this in the future. */
2531 if (EDGE_COUNT (then_bb
->succs
) == 0)
2533 if (EDGE_COUNT (else_bb
->preds
) == 1)
2535 rtx last_insn
= BB_END (then_bb
);
2538 && NOTE_P (last_insn
)
2539 && last_insn
!= BB_HEAD (then_bb
))
2540 last_insn
= PREV_INSN (last_insn
);
2543 && JUMP_P (last_insn
)
2544 && ! simplejump_p (last_insn
))
2548 else_bb
= NULL_BLOCK
;
2554 /* If the THEN block's successor is the other edge out of the TEST block,
2555 then we have an IF-THEN combo without an ELSE. */
2556 else if (EDGE_SUCC (then_bb
, 0)->dest
== else_bb
)
2559 else_bb
= NULL_BLOCK
;
2562 /* If the THEN and ELSE block meet in a subsequent block, and the ELSE
2563 has exactly one predecessor and one successor, and the outgoing edge
2564 is not complex, then we have an IF-THEN-ELSE combo. */
2565 else if (EDGE_COUNT (else_bb
->succs
) == 1
2566 && EDGE_SUCC (then_bb
, 0)->dest
== EDGE_SUCC (else_bb
, 0)->dest
2567 && EDGE_COUNT (else_bb
->preds
) == 1
2568 && ! (EDGE_SUCC (else_bb
, 0)->flags
& EDGE_COMPLEX
)
2569 && ! (flow2_completed
&& tablejump_p (BB_END (else_bb
), NULL
, NULL
)))
2570 join_bb
= EDGE_SUCC (else_bb
, 0)->dest
;
2572 /* Otherwise it is not an IF-THEN or IF-THEN-ELSE combination. */
2576 num_possible_if_blocks
++;
2581 "\nIF-THEN%s block found, pass %d, start block %d "
2582 "[insn %d], then %d [%d]",
2583 (else_bb
) ? "-ELSE" : "",
2586 BB_HEAD (test_bb
) ? (int)INSN_UID (BB_HEAD (test_bb
)) : -1,
2588 BB_HEAD (then_bb
) ? (int)INSN_UID (BB_HEAD (then_bb
)) : -1);
2591 fprintf (dump_file
, ", else %d [%d]",
2593 BB_HEAD (else_bb
) ? (int)INSN_UID (BB_HEAD (else_bb
)) : -1);
2595 fprintf (dump_file
, ", join %d [%d]",
2597 BB_HEAD (join_bb
) ? (int)INSN_UID (BB_HEAD (join_bb
)) : -1);
2599 if (ce_info
->num_multiple_test_blocks
> 0)
2600 fprintf (dump_file
, ", %d %s block%s last test %d [%d]",
2601 ce_info
->num_multiple_test_blocks
,
2602 (ce_info
->and_and_p
) ? "&&" : "||",
2603 (ce_info
->num_multiple_test_blocks
== 1) ? "" : "s",
2604 ce_info
->last_test_bb
->index
,
2605 ((BB_HEAD (ce_info
->last_test_bb
))
2606 ? (int)INSN_UID (BB_HEAD (ce_info
->last_test_bb
))
2609 fputc ('\n', dump_file
);
2612 /* Make sure IF, THEN, and ELSE, blocks are adjacent. Actually, we get the
2613 first condition for free, since we've already asserted that there's a
2614 fallthru edge from IF to THEN. Likewise for the && and || blocks, since
2615 we checked the FALLTHRU flag, those are already adjacent to the last IF
2617 /* ??? As an enhancement, move the ELSE block. Have to deal with
2618 BLOCK notes, if by no other means than aborting the merge if they
2619 exist. Sticky enough I don't want to think about it now. */
2621 if (else_bb
&& (next
= next
->next_bb
) != else_bb
)
2623 if ((next
= next
->next_bb
) != join_bb
&& join_bb
!= EXIT_BLOCK_PTR
)
2631 /* Do the real work. */
2632 ce_info
->else_bb
= else_bb
;
2633 ce_info
->join_bb
= join_bb
;
2635 return process_if_block (ce_info
);
2638 /* Convert a branch over a trap, or a branch
2639 to a trap, into a conditional trap. */
2642 find_cond_trap (basic_block test_bb
, edge then_edge
, edge else_edge
)
2644 basic_block then_bb
= then_edge
->dest
;
2645 basic_block else_bb
= else_edge
->dest
;
2646 basic_block other_bb
, trap_bb
;
2647 rtx trap
, jump
, cond
, cond_earliest
, seq
;
2650 /* Locate the block with the trap instruction. */
2651 /* ??? While we look for no successors, we really ought to allow
2652 EH successors. Need to fix merge_if_block for that to work. */
2653 if ((trap
= block_has_only_trap (then_bb
)) != NULL
)
2654 trap_bb
= then_bb
, other_bb
= else_bb
;
2655 else if ((trap
= block_has_only_trap (else_bb
)) != NULL
)
2656 trap_bb
= else_bb
, other_bb
= then_bb
;
2662 fprintf (dump_file
, "\nTRAP-IF block found, start %d, trap %d\n",
2663 test_bb
->index
, trap_bb
->index
);
2666 /* If this is not a standard conditional jump, we can't parse it. */
2667 jump
= BB_END (test_bb
);
2668 cond
= noce_get_condition (jump
, &cond_earliest
);
2672 /* If the conditional jump is more than just a conditional jump, then
2673 we can not do if-conversion on this block. */
2674 if (! onlyjump_p (jump
))
2677 /* We must be comparing objects whose modes imply the size. */
2678 if (GET_MODE (XEXP (cond
, 0)) == BLKmode
)
2681 /* Reverse the comparison code, if necessary. */
2682 code
= GET_CODE (cond
);
2683 if (then_bb
== trap_bb
)
2685 code
= reversed_comparison_code (cond
, jump
);
2686 if (code
== UNKNOWN
)
2690 /* Attempt to generate the conditional trap. */
2691 seq
= gen_cond_trap (code
, XEXP (cond
, 0),
2693 TRAP_CODE (PATTERN (trap
)));
2699 /* Emit the new insns before cond_earliest. */
2700 emit_insn_before_setloc (seq
, cond_earliest
, INSN_LOCATOR (trap
));
2702 /* Delete the trap block if possible. */
2703 remove_edge (trap_bb
== then_bb
? then_edge
: else_edge
);
2704 if (EDGE_COUNT (trap_bb
->preds
) == 0)
2705 delete_basic_block (trap_bb
);
2707 /* If the non-trap block and the test are now adjacent, merge them.
2708 Otherwise we must insert a direct branch. */
2709 if (test_bb
->next_bb
== other_bb
)
2711 struct ce_if_block new_ce_info
;
2713 memset (&new_ce_info
, '\0', sizeof (new_ce_info
));
2714 new_ce_info
.test_bb
= test_bb
;
2715 new_ce_info
.then_bb
= NULL
;
2716 new_ce_info
.else_bb
= NULL
;
2717 new_ce_info
.join_bb
= other_bb
;
2718 merge_if_block (&new_ce_info
);
2724 lab
= JUMP_LABEL (jump
);
2725 newjump
= emit_jump_insn_after (gen_jump (lab
), jump
);
2726 LABEL_NUSES (lab
) += 1;
2727 JUMP_LABEL (newjump
) = lab
;
2728 emit_barrier_after (newjump
);
2736 /* Subroutine of find_cond_trap: if BB contains only a trap insn,
2740 block_has_only_trap (basic_block bb
)
2744 /* We're not the exit block. */
2745 if (bb
== EXIT_BLOCK_PTR
)
2748 /* The block must have no successors. */
2749 if (EDGE_COUNT (bb
->succs
) > 0)
2752 /* The only instruction in the THEN block must be the trap. */
2753 trap
= first_active_insn (bb
);
2754 if (! (trap
== BB_END (bb
)
2755 && GET_CODE (PATTERN (trap
)) == TRAP_IF
2756 && TRAP_CONDITION (PATTERN (trap
)) == const_true_rtx
))
2762 /* Look for IF-THEN-ELSE cases in which one of THEN or ELSE is
2763 transformable, but not necessarily the other. There need be no
2766 Return TRUE if we were successful at converting the block.
2768 Cases we'd like to look at:
2771 if (test) goto over; // x not live
2779 if (! test) goto label;
2782 if (test) goto E; // x not live
2796 (3) // This one's really only interesting for targets that can do
2797 // multiway branching, e.g. IA-64 BBB bundles. For other targets
2798 // it results in multiple branches on a cache line, which often
2799 // does not sit well with predictors.
2801 if (test1) goto E; // predicted not taken
2817 (A) Don't do (2) if the branch is predicted against the block we're
2818 eliminating. Do it anyway if we can eliminate a branch; this requires
2819 that the sole successor of the eliminated block postdominate the other
2822 (B) With CE, on (3) we can steal from both sides of the if, creating
2831 Again, this is most useful if J postdominates.
2833 (C) CE substitutes for helpful life information.
2835 (D) These heuristics need a lot of work. */
2837 /* Tests for case 1 above. */
2840 find_if_case_1 (basic_block test_bb
, edge then_edge
, edge else_edge
)
2842 basic_block then_bb
= then_edge
->dest
;
2843 basic_block else_bb
= else_edge
->dest
, new_bb
;
2844 int then_bb_index
, bb_cost
;
2846 /* If we are partitioning hot/cold basic blocks, we don't want to
2847 mess up unconditional or indirect jumps that cross between hot
2848 and cold sections. */
2850 if (flag_reorder_blocks_and_partition
2851 && ((BB_END (then_bb
)
2852 && find_reg_note (BB_END (then_bb
), REG_CROSSING_JUMP
, NULL_RTX
))
2853 || (BB_END (else_bb
)
2854 && find_reg_note (BB_END (else_bb
), REG_CROSSING_JUMP
,
2858 /* THEN has one successor. */
2859 if (EDGE_COUNT (then_bb
->succs
) != 1)
2862 /* THEN does not fall through, but is not strange either. */
2863 if (EDGE_SUCC (then_bb
, 0)->flags
& (EDGE_COMPLEX
| EDGE_FALLTHRU
))
2866 /* THEN has one predecessor. */
2867 if (EDGE_COUNT (then_bb
->preds
) != 1)
2870 /* THEN must do something. */
2871 if (forwarder_block_p (then_bb
))
2874 num_possible_if_blocks
++;
2877 "\nIF-CASE-1 found, start %d, then %d\n",
2878 test_bb
->index
, then_bb
->index
);
2880 /* THEN is small. */
2881 bb_cost
= total_bb_rtx_cost (then_bb
);
2882 if (bb_cost
< 0 || bb_cost
>= COSTS_N_INSNS (BRANCH_COST
))
2885 /* Registers set are dead, or are predicable. */
2886 if (! dead_or_predicable (test_bb
, then_bb
, else_bb
,
2887 EDGE_SUCC (then_bb
, 0)->dest
, 1))
2890 /* Conversion went ok, including moving the insns and fixing up the
2891 jump. Adjust the CFG to match. */
2893 bitmap_operation (test_bb
->global_live_at_end
,
2894 else_bb
->global_live_at_start
,
2895 then_bb
->global_live_at_end
, BITMAP_IOR
);
2897 new_bb
= redirect_edge_and_branch_force (FALLTHRU_EDGE (test_bb
), else_bb
);
2898 then_bb_index
= then_bb
->index
;
2899 delete_basic_block (then_bb
);
2901 /* Make rest of code believe that the newly created block is the THEN_BB
2902 block we removed. */
2905 new_bb
->index
= then_bb_index
;
2906 BASIC_BLOCK (then_bb_index
) = new_bb
;
2907 new_bb
->partition
= test_bb
->partition
;
2909 /* We've possibly created jump to next insn, cleanup_cfg will solve that
2913 num_updated_if_blocks
++;
2918 /* Test for case 2 above. */
2921 find_if_case_2 (basic_block test_bb
, edge then_edge
, edge else_edge
)
2923 basic_block then_bb
= then_edge
->dest
;
2924 basic_block else_bb
= else_edge
->dest
;
2929 /* If we are partitioning hot/cold basic blocks, we don't want to
2930 mess up unconditional or indirect jumps that cross between hot
2931 and cold sections. */
2933 if (flag_reorder_blocks_and_partition
2934 && ((BB_END (then_bb
)
2935 && find_reg_note (BB_END (then_bb
), REG_CROSSING_JUMP
, NULL_RTX
))
2936 || (BB_END (else_bb
)
2937 && find_reg_note (BB_END (else_bb
), REG_CROSSING_JUMP
,
2941 /* ELSE has one successor. */
2942 if (EDGE_COUNT (else_bb
->succs
) != 1)
2945 else_succ
= EDGE_SUCC (else_bb
, 0);
2947 /* ELSE outgoing edge is not complex. */
2948 if (else_succ
->flags
& EDGE_COMPLEX
)
2951 /* ELSE has one predecessor. */
2952 if (EDGE_COUNT (else_bb
->preds
) != 1)
2955 /* THEN is not EXIT. */
2956 if (then_bb
->index
< 0)
2959 /* ELSE is predicted or SUCC(ELSE) postdominates THEN. */
2960 note
= find_reg_note (BB_END (test_bb
), REG_BR_PROB
, NULL_RTX
);
2961 if (note
&& INTVAL (XEXP (note
, 0)) >= REG_BR_PROB_BASE
/ 2)
2963 else if (else_succ
->dest
->index
< 0
2964 || dominated_by_p (CDI_POST_DOMINATORS
, then_bb
,
2970 num_possible_if_blocks
++;
2973 "\nIF-CASE-2 found, start %d, else %d\n",
2974 test_bb
->index
, else_bb
->index
);
2976 /* ELSE is small. */
2977 bb_cost
= total_bb_rtx_cost (else_bb
);
2978 if (bb_cost
< 0 || bb_cost
>= COSTS_N_INSNS (BRANCH_COST
))
2981 /* Registers set are dead, or are predicable. */
2982 if (! dead_or_predicable (test_bb
, else_bb
, then_bb
, else_succ
->dest
, 0))
2985 /* Conversion went ok, including moving the insns and fixing up the
2986 jump. Adjust the CFG to match. */
2988 bitmap_operation (test_bb
->global_live_at_end
,
2989 then_bb
->global_live_at_start
,
2990 else_bb
->global_live_at_end
, BITMAP_IOR
);
2992 delete_basic_block (else_bb
);
2995 num_updated_if_blocks
++;
2997 /* ??? We may now fallthru from one of THEN's successors into a join
2998 block. Rerun cleanup_cfg? Examine things manually? Wait? */
3003 /* A subroutine of dead_or_predicable called through for_each_rtx.
3004 Return 1 if a memory is found. */
3007 find_memory (rtx
*px
, void *data ATTRIBUTE_UNUSED
)
3012 /* Used by the code above to perform the actual rtl transformations.
3013 Return TRUE if successful.
3015 TEST_BB is the block containing the conditional branch. MERGE_BB
3016 is the block containing the code to manipulate. NEW_DEST is the
3017 label TEST_BB should be branching to after the conversion.
3018 REVERSEP is true if the sense of the branch should be reversed. */
3021 dead_or_predicable (basic_block test_bb
, basic_block merge_bb
,
3022 basic_block other_bb
, basic_block new_dest
, int reversep
)
3024 rtx head
, end
, jump
, earliest
= NULL_RTX
, old_dest
, new_label
= NULL_RTX
;
3026 jump
= BB_END (test_bb
);
3028 /* Find the extent of the real code in the merge block. */
3029 head
= BB_HEAD (merge_bb
);
3030 end
= BB_END (merge_bb
);
3033 head
= NEXT_INSN (head
);
3038 head
= end
= NULL_RTX
;
3041 head
= NEXT_INSN (head
);
3048 head
= end
= NULL_RTX
;
3051 end
= PREV_INSN (end
);
3054 /* Disable handling dead code by conditional execution if the machine needs
3055 to do anything funny with the tests, etc. */
3056 #ifndef IFCVT_MODIFY_TESTS
3057 if (HAVE_conditional_execution
)
3059 /* In the conditional execution case, we have things easy. We know
3060 the condition is reversible. We don't have to check life info
3061 because we're going to conditionally execute the code anyway.
3062 All that's left is making sure the insns involved can actually
3067 cond
= cond_exec_get_condition (jump
);
3071 prob_val
= find_reg_note (jump
, REG_BR_PROB
, NULL_RTX
);
3073 prob_val
= XEXP (prob_val
, 0);
3077 enum rtx_code rev
= reversed_comparison_code (cond
, jump
);
3080 cond
= gen_rtx_fmt_ee (rev
, GET_MODE (cond
), XEXP (cond
, 0),
3083 prob_val
= GEN_INT (REG_BR_PROB_BASE
- INTVAL (prob_val
));
3086 if (! cond_exec_process_insns ((ce_if_block_t
*)0, head
, end
, cond
,
3095 /* In the non-conditional execution case, we have to verify that there
3096 are no trapping operations, no calls, no references to memory, and
3097 that any registers modified are dead at the branch site. */
3099 rtx insn
, cond
, prev
;
3100 regset_head merge_set_head
, tmp_head
, test_live_head
, test_set_head
;
3101 regset merge_set
, tmp
, test_live
, test_set
;
3102 struct propagate_block_info
*pbi
;
3105 /* Check for no calls or trapping operations. */
3106 for (insn
= head
; ; insn
= NEXT_INSN (insn
))
3112 if (may_trap_p (PATTERN (insn
)))
3115 /* ??? Even non-trapping memories such as stack frame
3116 references must be avoided. For stores, we collect
3117 no lifetime info; for reads, we'd have to assert
3118 true_dependence false against every store in the
3120 if (for_each_rtx (&PATTERN (insn
), find_memory
, NULL
))
3127 if (! any_condjump_p (jump
))
3130 /* Find the extent of the conditional. */
3131 cond
= noce_get_condition (jump
, &earliest
);
3136 MERGE_SET = set of registers set in MERGE_BB
3137 TEST_LIVE = set of registers live at EARLIEST
3138 TEST_SET = set of registers set between EARLIEST and the
3139 end of the block. */
3141 tmp
= INITIALIZE_REG_SET (tmp_head
);
3142 merge_set
= INITIALIZE_REG_SET (merge_set_head
);
3143 test_live
= INITIALIZE_REG_SET (test_live_head
);
3144 test_set
= INITIALIZE_REG_SET (test_set_head
);
3146 /* ??? bb->local_set is only valid during calculate_global_regs_live,
3147 so we must recompute usage for MERGE_BB. Not so bad, I suppose,
3148 since we've already asserted that MERGE_BB is small. */
3149 propagate_block (merge_bb
, tmp
, merge_set
, merge_set
, 0);
3151 /* For small register class machines, don't lengthen lifetimes of
3152 hard registers before reload. */
3153 if (SMALL_REGISTER_CLASSES
&& ! reload_completed
)
3155 EXECUTE_IF_SET_IN_BITMAP
3158 if (i
< FIRST_PSEUDO_REGISTER
3160 && ! global_regs
[i
])
3165 /* For TEST, we're interested in a range of insns, not a whole block.
3166 Moreover, we're interested in the insns live from OTHER_BB. */
3168 COPY_REG_SET (test_live
, other_bb
->global_live_at_start
);
3169 pbi
= init_propagate_block_info (test_bb
, test_live
, test_set
, test_set
,
3172 for (insn
= jump
; ; insn
= prev
)
3174 prev
= propagate_one_insn (pbi
, insn
);
3175 if (insn
== earliest
)
3179 free_propagate_block_info (pbi
);
3181 /* We can perform the transformation if
3182 MERGE_SET & (TEST_SET | TEST_LIVE)
3184 TEST_SET & merge_bb->global_live_at_start
3187 bitmap_operation (tmp
, test_set
, test_live
, BITMAP_IOR
);
3188 bitmap_operation (tmp
, tmp
, merge_set
, BITMAP_AND
);
3189 EXECUTE_IF_SET_IN_BITMAP(tmp
, 0, i
, fail
= 1);
3191 bitmap_operation (tmp
, test_set
, merge_bb
->global_live_at_start
,
3193 EXECUTE_IF_SET_IN_BITMAP(tmp
, 0, i
, fail
= 1);
3196 FREE_REG_SET (merge_set
);
3197 FREE_REG_SET (test_live
);
3198 FREE_REG_SET (test_set
);
3205 /* We don't want to use normal invert_jump or redirect_jump because
3206 we don't want to delete_insn called. Also, we want to do our own
3207 change group management. */
3209 old_dest
= JUMP_LABEL (jump
);
3210 if (other_bb
!= new_dest
)
3212 new_label
= block_label (new_dest
);
3214 ? ! invert_jump_1 (jump
, new_label
)
3215 : ! redirect_jump_1 (jump
, new_label
))
3219 if (! apply_change_group ())
3222 if (other_bb
!= new_dest
)
3225 LABEL_NUSES (old_dest
) -= 1;
3227 LABEL_NUSES (new_label
) += 1;
3228 JUMP_LABEL (jump
) = new_label
;
3230 invert_br_probabilities (jump
);
3232 redirect_edge_succ (BRANCH_EDGE (test_bb
), new_dest
);
3235 gcov_type count
, probability
;
3236 count
= BRANCH_EDGE (test_bb
)->count
;
3237 BRANCH_EDGE (test_bb
)->count
= FALLTHRU_EDGE (test_bb
)->count
;
3238 FALLTHRU_EDGE (test_bb
)->count
= count
;
3239 probability
= BRANCH_EDGE (test_bb
)->probability
;
3240 BRANCH_EDGE (test_bb
)->probability
3241 = FALLTHRU_EDGE (test_bb
)->probability
;
3242 FALLTHRU_EDGE (test_bb
)->probability
= probability
;
3243 update_br_prob_note (test_bb
);
3247 /* Move the insns out of MERGE_BB to before the branch. */
3250 if (end
== BB_END (merge_bb
))
3251 BB_END (merge_bb
) = PREV_INSN (head
);
3253 if (squeeze_notes (&head
, &end
))
3256 reorder_insns (head
, end
, PREV_INSN (earliest
));
3259 /* Remove the jump and edge if we can. */
3260 if (other_bb
== new_dest
)
3263 remove_edge (BRANCH_EDGE (test_bb
));
3264 /* ??? Can't merge blocks here, as then_bb is still in use.
3265 At minimum, the merge will get done just before bb-reorder. */
3275 /* Main entry point for all if-conversion. */
3278 if_convert (int x_life_data_ok
)
3283 num_possible_if_blocks
= 0;
3284 num_updated_if_blocks
= 0;
3285 num_true_changes
= 0;
3286 life_data_ok
= (x_life_data_ok
!= 0);
3288 if ((! targetm
.cannot_modify_jumps_p ())
3289 && (!flag_reorder_blocks_and_partition
|| !no_new_pseudos
3290 || !targetm
.have_named_sections
))
3291 mark_loop_exit_edges ();
3293 /* Compute postdominators if we think we'll use them. */
3294 if (HAVE_conditional_execution
|| life_data_ok
)
3295 calculate_dominance_info (CDI_POST_DOMINATORS
);
3300 /* Go through each of the basic blocks looking for things to convert. If we
3301 have conditional execution, we make multiple passes to allow us to handle
3302 IF-THEN{-ELSE} blocks within other IF-THEN{-ELSE} blocks. */
3306 cond_exec_changed_p
= FALSE
;
3309 #ifdef IFCVT_MULTIPLE_DUMPS
3310 if (dump_file
&& pass
> 1)
3311 fprintf (dump_file
, "\n\n========== Pass %d ==========\n", pass
);
3317 while ((new_bb
= find_if_header (bb
, pass
)))
3321 #ifdef IFCVT_MULTIPLE_DUMPS
3322 if (dump_file
&& cond_exec_changed_p
)
3323 print_rtl_with_bb (dump_file
, get_insns ());
3326 while (cond_exec_changed_p
);
3328 #ifdef IFCVT_MULTIPLE_DUMPS
3330 fprintf (dump_file
, "\n\n========== no more changes\n");
3333 free_dominance_info (CDI_POST_DOMINATORS
);
3338 clear_aux_for_blocks ();
3340 /* Rebuild life info for basic blocks that require it. */
3341 if (num_true_changes
&& life_data_ok
)
3343 /* If we allocated new pseudos, we must resize the array for sched1. */
3344 if (max_regno
< max_reg_num ())
3346 max_regno
= max_reg_num ();
3347 allocate_reg_info (max_regno
, FALSE
, FALSE
);
3349 update_life_info_in_dirty_blocks (UPDATE_LIFE_GLOBAL_RM_NOTES
,
3350 PROP_DEATH_NOTES
| PROP_SCAN_DEAD_CODE
3351 | PROP_KILL_DEAD_CODE
);
3354 /* Write the final stats. */
3355 if (dump_file
&& num_possible_if_blocks
> 0)
3358 "\n%d possible IF blocks searched.\n",
3359 num_possible_if_blocks
);
3361 "%d IF blocks converted.\n",
3362 num_updated_if_blocks
);
3364 "%d true changes made.\n\n\n",
3368 #ifdef ENABLE_CHECKING
3369 verify_flow_info ();