1 /* If-conversion support.
2 Copyright (C) 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007
3 Free Software Foundation, Inc.
5 This file is part of GCC.
7 GCC is free software; you can redistribute it and/or modify it
8 under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 2, or (at your option)
12 GCC is distributed in the hope that it will be useful, but WITHOUT
13 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
14 or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public
15 License for more details.
17 You should have received a copy of the GNU General Public License
18 along with GCC; see the file COPYING. If not, write to the Free
19 Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA
24 #include "coretypes.h"
31 #include "insn-config.h"
34 #include "hard-reg-set.h"
35 #include "basic-block.h"
45 #include "tree-pass.h"
50 #ifndef HAVE_conditional_execution
51 #define HAVE_conditional_execution 0
53 #ifndef HAVE_conditional_move
54 #define HAVE_conditional_move 0
65 #ifndef HAVE_conditional_trap
66 #define HAVE_conditional_trap 0
69 #ifndef MAX_CONDITIONAL_EXECUTE
70 #define MAX_CONDITIONAL_EXECUTE (BRANCH_COST + 1)
73 #define NULL_BLOCK ((basic_block) NULL)
75 /* # of IF-THEN or IF-THEN-ELSE blocks we looked at */
76 static int num_possible_if_blocks
;
78 /* # of IF-THEN or IF-THEN-ELSE blocks were converted to conditional
80 static int num_updated_if_blocks
;
82 /* # of changes made which require life information to be updated. */
83 static int num_true_changes
;
85 /* Whether conditional execution changes were made. */
86 static int cond_exec_changed_p
;
88 /* True if life data ok at present. */
89 static bool life_data_ok
;
91 /* Forward references. */
92 static int count_bb_insns (basic_block
);
93 static bool cheap_bb_rtx_cost_p (basic_block
, int);
94 static rtx
first_active_insn (basic_block
);
95 static rtx
last_active_insn (basic_block
, int);
96 static basic_block
block_fallthru (basic_block
);
97 static int cond_exec_process_insns (ce_if_block_t
*, rtx
, rtx
, rtx
, rtx
, int);
98 static rtx
cond_exec_get_condition (rtx
);
99 static rtx
noce_get_condition (rtx
, rtx
*, bool);
100 static int noce_operand_ok (rtx
);
101 static void merge_if_block (ce_if_block_t
*);
102 static int find_cond_trap (basic_block
, edge
, edge
);
103 static basic_block
find_if_header (basic_block
, int);
104 static int block_jumps_and_fallthru_p (basic_block
, basic_block
);
105 static int noce_find_if_block (basic_block
, edge
, edge
, int);
106 static int cond_exec_find_if_block (ce_if_block_t
*);
107 static int find_if_case_1 (basic_block
, edge
, edge
);
108 static int find_if_case_2 (basic_block
, edge
, edge
);
109 static int find_memory (rtx
*, void *);
110 static int dead_or_predicable (basic_block
, basic_block
, basic_block
,
112 static void noce_emit_move_insn (rtx
, rtx
);
113 static rtx
block_has_only_trap (basic_block
);
115 /* Count the number of non-jump active insns in BB. */
118 count_bb_insns (basic_block bb
)
121 rtx insn
= BB_HEAD (bb
);
125 if (CALL_P (insn
) || NONJUMP_INSN_P (insn
))
128 if (insn
== BB_END (bb
))
130 insn
= NEXT_INSN (insn
);
136 /* Determine whether the total insn_rtx_cost on non-jump insns in
137 basic block BB is less than MAX_COST. This function returns
138 false if the cost of any instruction could not be estimated. */
141 cheap_bb_rtx_cost_p (basic_block bb
, int max_cost
)
144 rtx insn
= BB_HEAD (bb
);
148 if (NONJUMP_INSN_P (insn
))
150 int cost
= insn_rtx_cost (PATTERN (insn
));
154 /* If this instruction is the load or set of a "stack" register,
155 such as a floating point register on x87, then the cost of
156 speculatively executing this insn may need to include
157 the additional cost of popping its result off of the
158 register stack. Unfortunately, correctly recognizing and
159 accounting for this additional overhead is tricky, so for
160 now we simply prohibit such speculative execution. */
163 rtx set
= single_set (insn
);
164 if (set
&& STACK_REG_P (SET_DEST (set
)))
170 if (count
>= max_cost
)
173 else if (CALL_P (insn
))
176 if (insn
== BB_END (bb
))
178 insn
= NEXT_INSN (insn
);
184 /* Return the first non-jump active insn in the basic block. */
187 first_active_insn (basic_block bb
)
189 rtx insn
= BB_HEAD (bb
);
193 if (insn
== BB_END (bb
))
195 insn
= NEXT_INSN (insn
);
198 while (NOTE_P (insn
))
200 if (insn
== BB_END (bb
))
202 insn
= NEXT_INSN (insn
);
211 /* Return the last non-jump active (non-jump) insn in the basic block. */
214 last_active_insn (basic_block bb
, int skip_use_p
)
216 rtx insn
= BB_END (bb
);
217 rtx head
= BB_HEAD (bb
);
222 && NONJUMP_INSN_P (insn
)
223 && GET_CODE (PATTERN (insn
)) == USE
))
227 insn
= PREV_INSN (insn
);
236 /* Return the basic block reached by falling though the basic block BB. */
239 block_fallthru (basic_block bb
)
244 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
245 if (e
->flags
& EDGE_FALLTHRU
)
248 return (e
) ? e
->dest
: NULL_BLOCK
;
251 /* Go through a bunch of insns, converting them to conditional
252 execution format if possible. Return TRUE if all of the non-note
253 insns were processed. */
256 cond_exec_process_insns (ce_if_block_t
*ce_info ATTRIBUTE_UNUSED
,
257 /* if block information */rtx start
,
258 /* first insn to look at */rtx end
,
259 /* last insn to look at */rtx test
,
260 /* conditional execution test */rtx prob_val
,
261 /* probability of branch taken. */int mod_ok
)
263 int must_be_last
= FALSE
;
271 for (insn
= start
; ; insn
= NEXT_INSN (insn
))
276 gcc_assert(NONJUMP_INSN_P (insn
) || CALL_P (insn
));
278 /* Remove USE insns that get in the way. */
279 if (reload_completed
&& GET_CODE (PATTERN (insn
)) == USE
)
281 /* ??? Ug. Actually unlinking the thing is problematic,
282 given what we'd have to coordinate with our callers. */
283 SET_INSN_DELETED (insn
);
287 /* Last insn wasn't last? */
291 if (modified_in_p (test
, insn
))
298 /* Now build the conditional form of the instruction. */
299 pattern
= PATTERN (insn
);
300 xtest
= copy_rtx (test
);
302 /* If this is already a COND_EXEC, rewrite the test to be an AND of the
304 if (GET_CODE (pattern
) == COND_EXEC
)
306 if (GET_MODE (xtest
) != GET_MODE (COND_EXEC_TEST (pattern
)))
309 xtest
= gen_rtx_AND (GET_MODE (xtest
), xtest
,
310 COND_EXEC_TEST (pattern
));
311 pattern
= COND_EXEC_CODE (pattern
);
314 pattern
= gen_rtx_COND_EXEC (VOIDmode
, xtest
, pattern
);
316 /* If the machine needs to modify the insn being conditionally executed,
317 say for example to force a constant integer operand into a temp
318 register, do so here. */
319 #ifdef IFCVT_MODIFY_INSN
320 IFCVT_MODIFY_INSN (ce_info
, pattern
, insn
);
325 validate_change (insn
, &PATTERN (insn
), pattern
, 1);
327 if (CALL_P (insn
) && prob_val
)
328 validate_change (insn
, ®_NOTES (insn
),
329 alloc_EXPR_LIST (REG_BR_PROB
, prob_val
,
330 REG_NOTES (insn
)), 1);
340 /* Return the condition for a jump. Do not do any special processing. */
343 cond_exec_get_condition (rtx jump
)
347 if (any_condjump_p (jump
))
348 test_if
= SET_SRC (pc_set (jump
));
351 cond
= XEXP (test_if
, 0);
353 /* If this branches to JUMP_LABEL when the condition is false,
354 reverse the condition. */
355 if (GET_CODE (XEXP (test_if
, 2)) == LABEL_REF
356 && XEXP (XEXP (test_if
, 2), 0) == JUMP_LABEL (jump
))
358 enum rtx_code rev
= reversed_comparison_code (cond
, jump
);
362 cond
= gen_rtx_fmt_ee (rev
, GET_MODE (cond
), XEXP (cond
, 0),
369 /* Given a simple IF-THEN or IF-THEN-ELSE block, attempt to convert it
370 to conditional execution. Return TRUE if we were successful at
371 converting the block. */
374 cond_exec_process_if_block (ce_if_block_t
* ce_info
,
375 /* if block information */int do_multiple_p
)
377 basic_block test_bb
= ce_info
->test_bb
; /* last test block */
378 basic_block then_bb
= ce_info
->then_bb
; /* THEN */
379 basic_block else_bb
= ce_info
->else_bb
; /* ELSE or NULL */
380 rtx test_expr
; /* expression in IF_THEN_ELSE that is tested */
381 rtx then_start
; /* first insn in THEN block */
382 rtx then_end
; /* last insn + 1 in THEN block */
383 rtx else_start
= NULL_RTX
; /* first insn in ELSE block or NULL */
384 rtx else_end
= NULL_RTX
; /* last insn + 1 in ELSE block */
385 int max
; /* max # of insns to convert. */
386 int then_mod_ok
; /* whether conditional mods are ok in THEN */
387 rtx true_expr
; /* test for else block insns */
388 rtx false_expr
; /* test for then block insns */
389 rtx true_prob_val
; /* probability of else block */
390 rtx false_prob_val
; /* probability of then block */
392 enum rtx_code false_code
;
394 /* If test is comprised of && or || elements, and we've failed at handling
395 all of them together, just use the last test if it is the special case of
396 && elements without an ELSE block. */
397 if (!do_multiple_p
&& ce_info
->num_multiple_test_blocks
)
399 if (else_bb
|| ! ce_info
->and_and_p
)
402 ce_info
->test_bb
= test_bb
= ce_info
->last_test_bb
;
403 ce_info
->num_multiple_test_blocks
= 0;
404 ce_info
->num_and_and_blocks
= 0;
405 ce_info
->num_or_or_blocks
= 0;
408 /* Find the conditional jump to the ELSE or JOIN part, and isolate
410 test_expr
= cond_exec_get_condition (BB_END (test_bb
));
414 /* If the conditional jump is more than just a conditional jump,
415 then we can not do conditional execution conversion on this block. */
416 if (! onlyjump_p (BB_END (test_bb
)))
419 /* Collect the bounds of where we're to search, skipping any labels, jumps
420 and notes at the beginning and end of the block. Then count the total
421 number of insns and see if it is small enough to convert. */
422 then_start
= first_active_insn (then_bb
);
423 then_end
= last_active_insn (then_bb
, TRUE
);
424 n_insns
= ce_info
->num_then_insns
= count_bb_insns (then_bb
);
425 max
= MAX_CONDITIONAL_EXECUTE
;
430 else_start
= first_active_insn (else_bb
);
431 else_end
= last_active_insn (else_bb
, TRUE
);
432 n_insns
+= ce_info
->num_else_insns
= count_bb_insns (else_bb
);
438 /* Map test_expr/test_jump into the appropriate MD tests to use on
439 the conditionally executed code. */
441 true_expr
= test_expr
;
443 false_code
= reversed_comparison_code (true_expr
, BB_END (test_bb
));
444 if (false_code
!= UNKNOWN
)
445 false_expr
= gen_rtx_fmt_ee (false_code
, GET_MODE (true_expr
),
446 XEXP (true_expr
, 0), XEXP (true_expr
, 1));
448 false_expr
= NULL_RTX
;
450 #ifdef IFCVT_MODIFY_TESTS
451 /* If the machine description needs to modify the tests, such as setting a
452 conditional execution register from a comparison, it can do so here. */
453 IFCVT_MODIFY_TESTS (ce_info
, true_expr
, false_expr
);
455 /* See if the conversion failed. */
456 if (!true_expr
|| !false_expr
)
460 true_prob_val
= find_reg_note (BB_END (test_bb
), REG_BR_PROB
, NULL_RTX
);
463 true_prob_val
= XEXP (true_prob_val
, 0);
464 false_prob_val
= GEN_INT (REG_BR_PROB_BASE
- INTVAL (true_prob_val
));
467 false_prob_val
= NULL_RTX
;
469 /* If we have && or || tests, do them here. These tests are in the adjacent
470 blocks after the first block containing the test. */
471 if (ce_info
->num_multiple_test_blocks
> 0)
473 basic_block bb
= test_bb
;
474 basic_block last_test_bb
= ce_info
->last_test_bb
;
483 enum rtx_code f_code
;
485 bb
= block_fallthru (bb
);
486 start
= first_active_insn (bb
);
487 end
= last_active_insn (bb
, TRUE
);
489 && ! cond_exec_process_insns (ce_info
, start
, end
, false_expr
,
490 false_prob_val
, FALSE
))
493 /* If the conditional jump is more than just a conditional jump, then
494 we can not do conditional execution conversion on this block. */
495 if (! onlyjump_p (BB_END (bb
)))
498 /* Find the conditional jump and isolate the test. */
499 t
= cond_exec_get_condition (BB_END (bb
));
503 f_code
= reversed_comparison_code (t
, BB_END (bb
));
504 if (f_code
== UNKNOWN
)
507 f
= gen_rtx_fmt_ee (f_code
, GET_MODE (t
), XEXP (t
, 0), XEXP (t
, 1));
508 if (ce_info
->and_and_p
)
510 t
= gen_rtx_AND (GET_MODE (t
), true_expr
, t
);
511 f
= gen_rtx_IOR (GET_MODE (t
), false_expr
, f
);
515 t
= gen_rtx_IOR (GET_MODE (t
), true_expr
, t
);
516 f
= gen_rtx_AND (GET_MODE (t
), false_expr
, f
);
519 /* If the machine description needs to modify the tests, such as
520 setting a conditional execution register from a comparison, it can
522 #ifdef IFCVT_MODIFY_MULTIPLE_TESTS
523 IFCVT_MODIFY_MULTIPLE_TESTS (ce_info
, bb
, t
, f
);
525 /* See if the conversion failed. */
533 while (bb
!= last_test_bb
);
536 /* For IF-THEN-ELSE blocks, we don't allow modifications of the test
537 on then THEN block. */
538 then_mod_ok
= (else_bb
== NULL_BLOCK
);
540 /* Go through the THEN and ELSE blocks converting the insns if possible
541 to conditional execution. */
545 || ! cond_exec_process_insns (ce_info
, then_start
, then_end
,
546 false_expr
, false_prob_val
,
550 if (else_bb
&& else_end
551 && ! cond_exec_process_insns (ce_info
, else_start
, else_end
,
552 true_expr
, true_prob_val
, TRUE
))
555 /* If we cannot apply the changes, fail. Do not go through the normal fail
556 processing, since apply_change_group will call cancel_changes. */
557 if (! apply_change_group ())
559 #ifdef IFCVT_MODIFY_CANCEL
560 /* Cancel any machine dependent changes. */
561 IFCVT_MODIFY_CANCEL (ce_info
);
566 #ifdef IFCVT_MODIFY_FINAL
567 /* Do any machine dependent final modifications. */
568 IFCVT_MODIFY_FINAL (ce_info
);
571 /* Conversion succeeded. */
573 fprintf (dump_file
, "%d insn%s converted to conditional execution.\n",
574 n_insns
, (n_insns
== 1) ? " was" : "s were");
576 /* Merge the blocks! */
577 merge_if_block (ce_info
);
578 cond_exec_changed_p
= TRUE
;
582 #ifdef IFCVT_MODIFY_CANCEL
583 /* Cancel any machine dependent changes. */
584 IFCVT_MODIFY_CANCEL (ce_info
);
591 /* Used by noce_process_if_block to communicate with its subroutines.
593 The subroutines know that A and B may be evaluated freely. They
594 know that X is a register. They should insert new instructions
595 before cond_earliest. */
599 /* The basic blocks that make up the IF-THEN-{ELSE-,}JOIN block. */
600 basic_block test_bb
, then_bb
, else_bb
, join_bb
;
602 /* The jump that ends TEST_BB. */
605 /* The jump condition. */
608 /* New insns should be inserted before this one. */
611 /* Insns in the THEN and ELSE block. There is always just this
612 one insns in those blocks. The insns are single_set insns.
613 If there was no ELSE block, INSN_B is the last insn before
614 COND_EARLIEST, or NULL_RTX. In the former case, the insn
615 operands are still valid, as if INSN_B was moved down below
619 /* The SET_SRC of INSN_A and INSN_B. */
622 /* The SET_DEST of INSN_A. */
625 /* True if this if block is not canonical. In the canonical form of
626 if blocks, the THEN_BB is the block reached via the fallthru edge
627 from TEST_BB. For the noce transformations, we allow the symmetric
629 bool then_else_reversed
;
632 static rtx
noce_emit_store_flag (struct noce_if_info
*, rtx
, int, int);
633 static int noce_try_move (struct noce_if_info
*);
634 static int noce_try_store_flag (struct noce_if_info
*);
635 static int noce_try_addcc (struct noce_if_info
*);
636 static int noce_try_store_flag_constants (struct noce_if_info
*);
637 static int noce_try_store_flag_mask (struct noce_if_info
*);
638 static rtx
noce_emit_cmove (struct noce_if_info
*, rtx
, enum rtx_code
, rtx
,
640 static int noce_try_cmove (struct noce_if_info
*);
641 static int noce_try_cmove_arith (struct noce_if_info
*);
642 static rtx
noce_get_alt_condition (struct noce_if_info
*, rtx
, rtx
*);
643 static int noce_try_minmax (struct noce_if_info
*);
644 static int noce_try_abs (struct noce_if_info
*);
645 static int noce_try_sign_mask (struct noce_if_info
*);
647 /* Helper function for noce_try_store_flag*. */
650 noce_emit_store_flag (struct noce_if_info
*if_info
, rtx x
, int reversep
,
653 rtx cond
= if_info
->cond
;
657 cond_complex
= (! general_operand (XEXP (cond
, 0), VOIDmode
)
658 || ! general_operand (XEXP (cond
, 1), VOIDmode
));
660 /* If earliest == jump, or when the condition is complex, try to
661 build the store_flag insn directly. */
664 cond
= XEXP (SET_SRC (pc_set (if_info
->jump
)), 0);
667 code
= reversed_comparison_code (cond
, if_info
->jump
);
669 code
= GET_CODE (cond
);
671 if ((if_info
->cond_earliest
== if_info
->jump
|| cond_complex
)
672 && (normalize
== 0 || STORE_FLAG_VALUE
== normalize
))
676 tmp
= gen_rtx_fmt_ee (code
, GET_MODE (x
), XEXP (cond
, 0),
678 tmp
= gen_rtx_SET (VOIDmode
, x
, tmp
);
681 tmp
= emit_insn (tmp
);
683 if (recog_memoized (tmp
) >= 0)
689 if_info
->cond_earliest
= if_info
->jump
;
697 /* Don't even try if the comparison operands or the mode of X are weird. */
698 if (cond_complex
|| !SCALAR_INT_MODE_P (GET_MODE (x
)))
701 return emit_store_flag (x
, code
, XEXP (cond
, 0),
702 XEXP (cond
, 1), VOIDmode
,
703 (code
== LTU
|| code
== LEU
704 || code
== GEU
|| code
== GTU
), normalize
);
707 /* Emit instruction to move an rtx, possibly into STRICT_LOW_PART.
708 X is the destination/target and Y is the value to copy. */
711 noce_emit_move_insn (rtx x
, rtx y
)
713 enum machine_mode outmode
;
717 if (GET_CODE (x
) != STRICT_LOW_PART
)
719 rtx seq
, insn
, target
;
723 /* Check that the SET_SRC is reasonable before calling emit_move_insn,
724 otherwise construct a suitable SET pattern ourselves. */
725 insn
= (OBJECT_P (y
) || CONSTANT_P (y
) || GET_CODE (y
) == SUBREG
)
726 ? emit_move_insn (x
, y
)
727 : emit_insn (gen_rtx_SET (VOIDmode
, x
, y
));
731 if (recog_memoized (insn
) <= 0)
733 if (GET_CODE (x
) == ZERO_EXTRACT
)
735 rtx op
= XEXP (x
, 0);
736 unsigned HOST_WIDE_INT size
= INTVAL (XEXP (x
, 1));
737 unsigned HOST_WIDE_INT start
= INTVAL (XEXP (x
, 2));
739 /* store_bit_field expects START to be relative to
740 BYTES_BIG_ENDIAN and adjusts this value for machines with
741 BITS_BIG_ENDIAN != BYTES_BIG_ENDIAN. In order to be able to
742 invoke store_bit_field again it is necessary to have the START
743 value from the first call. */
744 if (BITS_BIG_ENDIAN
!= BYTES_BIG_ENDIAN
)
747 start
= BITS_PER_UNIT
- start
- size
;
750 gcc_assert (REG_P (op
));
751 start
= BITS_PER_WORD
- start
- size
;
755 gcc_assert (start
< (MEM_P (op
) ? BITS_PER_UNIT
: BITS_PER_WORD
));
756 store_bit_field (op
, size
, start
, GET_MODE (x
), y
);
760 switch (GET_RTX_CLASS (GET_CODE (y
)))
763 ot
= code_to_optab
[GET_CODE (y
)];
767 target
= expand_unop (GET_MODE (y
), ot
, XEXP (y
, 0), x
, 0);
768 if (target
!= NULL_RTX
)
771 emit_move_insn (x
, target
);
780 ot
= code_to_optab
[GET_CODE (y
)];
784 target
= expand_binop (GET_MODE (y
), ot
,
785 XEXP (y
, 0), XEXP (y
, 1),
787 if (target
!= NULL_RTX
)
790 emit_move_insn (x
, target
);
807 inner
= XEXP (outer
, 0);
808 outmode
= GET_MODE (outer
);
809 bitpos
= SUBREG_BYTE (outer
) * BITS_PER_UNIT
;
810 store_bit_field (inner
, GET_MODE_BITSIZE (outmode
), bitpos
, outmode
, y
);
813 /* Return sequence of instructions generated by if conversion. This
814 function calls end_sequence() to end the current stream, ensures
815 that are instructions are unshared, recognizable non-jump insns.
816 On failure, this function returns a NULL_RTX. */
819 end_ifcvt_sequence (struct noce_if_info
*if_info
)
822 rtx seq
= get_insns ();
824 set_used_flags (if_info
->x
);
825 set_used_flags (if_info
->cond
);
826 unshare_all_rtl_in_chain (seq
);
829 /* Make sure that all of the instructions emitted are recognizable,
830 and that we haven't introduced a new jump instruction.
831 As an exercise for the reader, build a general mechanism that
832 allows proper placement of required clobbers. */
833 for (insn
= seq
; insn
; insn
= NEXT_INSN (insn
))
835 || recog_memoized (insn
) == -1)
841 /* Convert "if (a != b) x = a; else x = b" into "x = a" and
842 "if (a == b) x = a; else x = b" into "x = b". */
845 noce_try_move (struct noce_if_info
*if_info
)
847 rtx cond
= if_info
->cond
;
848 enum rtx_code code
= GET_CODE (cond
);
851 if (code
!= NE
&& code
!= EQ
)
854 /* This optimization isn't valid if either A or B could be a NaN
856 if (HONOR_NANS (GET_MODE (if_info
->x
))
857 || HONOR_SIGNED_ZEROS (GET_MODE (if_info
->x
)))
860 /* Check whether the operands of the comparison are A and in
862 if ((rtx_equal_p (if_info
->a
, XEXP (cond
, 0))
863 && rtx_equal_p (if_info
->b
, XEXP (cond
, 1)))
864 || (rtx_equal_p (if_info
->a
, XEXP (cond
, 1))
865 && rtx_equal_p (if_info
->b
, XEXP (cond
, 0))))
867 y
= (code
== EQ
) ? if_info
->a
: if_info
->b
;
869 /* Avoid generating the move if the source is the destination. */
870 if (! rtx_equal_p (if_info
->x
, y
))
873 noce_emit_move_insn (if_info
->x
, y
);
874 seq
= end_ifcvt_sequence (if_info
);
878 emit_insn_before_setloc (seq
, if_info
->jump
,
879 INSN_LOCATOR (if_info
->insn_a
));
886 /* Convert "if (test) x = 1; else x = 0".
888 Only try 0 and STORE_FLAG_VALUE here. Other combinations will be
889 tried in noce_try_store_flag_constants after noce_try_cmove has had
890 a go at the conversion. */
893 noce_try_store_flag (struct noce_if_info
*if_info
)
898 if (GET_CODE (if_info
->b
) == CONST_INT
899 && INTVAL (if_info
->b
) == STORE_FLAG_VALUE
900 && if_info
->a
== const0_rtx
)
902 else if (if_info
->b
== const0_rtx
903 && GET_CODE (if_info
->a
) == CONST_INT
904 && INTVAL (if_info
->a
) == STORE_FLAG_VALUE
905 && (reversed_comparison_code (if_info
->cond
, if_info
->jump
)
913 target
= noce_emit_store_flag (if_info
, if_info
->x
, reversep
, 0);
916 if (target
!= if_info
->x
)
917 noce_emit_move_insn (if_info
->x
, target
);
919 seq
= end_ifcvt_sequence (if_info
);
923 emit_insn_before_setloc (seq
, if_info
->jump
,
924 INSN_LOCATOR (if_info
->insn_a
));
934 /* Convert "if (test) x = a; else x = b", for A and B constant. */
937 noce_try_store_flag_constants (struct noce_if_info
*if_info
)
941 HOST_WIDE_INT itrue
, ifalse
, diff
, tmp
;
942 int normalize
, can_reverse
;
943 enum machine_mode mode
;
945 if (GET_CODE (if_info
->a
) == CONST_INT
946 && GET_CODE (if_info
->b
) == CONST_INT
)
948 mode
= GET_MODE (if_info
->x
);
949 ifalse
= INTVAL (if_info
->a
);
950 itrue
= INTVAL (if_info
->b
);
952 /* Make sure we can represent the difference between the two values. */
953 if ((itrue
- ifalse
> 0)
954 != ((ifalse
< 0) != (itrue
< 0) ? ifalse
< 0 : ifalse
< itrue
))
957 diff
= trunc_int_for_mode (itrue
- ifalse
, mode
);
959 can_reverse
= (reversed_comparison_code (if_info
->cond
, if_info
->jump
)
963 if (diff
== STORE_FLAG_VALUE
|| diff
== -STORE_FLAG_VALUE
)
965 else if (ifalse
== 0 && exact_log2 (itrue
) >= 0
966 && (STORE_FLAG_VALUE
== 1
967 || BRANCH_COST
>= 2))
969 else if (itrue
== 0 && exact_log2 (ifalse
) >= 0 && can_reverse
970 && (STORE_FLAG_VALUE
== 1 || BRANCH_COST
>= 2))
971 normalize
= 1, reversep
= 1;
973 && (STORE_FLAG_VALUE
== -1
974 || BRANCH_COST
>= 2))
976 else if (ifalse
== -1 && can_reverse
977 && (STORE_FLAG_VALUE
== -1 || BRANCH_COST
>= 2))
978 normalize
= -1, reversep
= 1;
979 else if ((BRANCH_COST
>= 2 && STORE_FLAG_VALUE
== -1)
987 tmp
= itrue
; itrue
= ifalse
; ifalse
= tmp
;
988 diff
= trunc_int_for_mode (-diff
, mode
);
992 target
= noce_emit_store_flag (if_info
, if_info
->x
, reversep
, normalize
);
999 /* if (test) x = 3; else x = 4;
1000 => x = 3 + (test == 0); */
1001 if (diff
== STORE_FLAG_VALUE
|| diff
== -STORE_FLAG_VALUE
)
1003 target
= expand_simple_binop (mode
,
1004 (diff
== STORE_FLAG_VALUE
1006 GEN_INT (ifalse
), target
, if_info
->x
, 0,
1010 /* if (test) x = 8; else x = 0;
1011 => x = (test != 0) << 3; */
1012 else if (ifalse
== 0 && (tmp
= exact_log2 (itrue
)) >= 0)
1014 target
= expand_simple_binop (mode
, ASHIFT
,
1015 target
, GEN_INT (tmp
), if_info
->x
, 0,
1019 /* if (test) x = -1; else x = b;
1020 => x = -(test != 0) | b; */
1021 else if (itrue
== -1)
1023 target
= expand_simple_binop (mode
, IOR
,
1024 target
, GEN_INT (ifalse
), if_info
->x
, 0,
1028 /* if (test) x = a; else x = b;
1029 => x = (-(test != 0) & (b - a)) + a; */
1032 target
= expand_simple_binop (mode
, AND
,
1033 target
, GEN_INT (diff
), if_info
->x
, 0,
1036 target
= expand_simple_binop (mode
, PLUS
,
1037 target
, GEN_INT (ifalse
),
1038 if_info
->x
, 0, OPTAB_WIDEN
);
1047 if (target
!= if_info
->x
)
1048 noce_emit_move_insn (if_info
->x
, target
);
1050 seq
= end_ifcvt_sequence (if_info
);
1054 emit_insn_before_setloc (seq
, if_info
->jump
,
1055 INSN_LOCATOR (if_info
->insn_a
));
1062 /* Convert "if (test) foo++" into "foo += (test != 0)", and
1063 similarly for "foo--". */
1066 noce_try_addcc (struct noce_if_info
*if_info
)
1069 int subtract
, normalize
;
1071 if (GET_CODE (if_info
->a
) == PLUS
1072 && rtx_equal_p (XEXP (if_info
->a
, 0), if_info
->b
)
1073 && (reversed_comparison_code (if_info
->cond
, if_info
->jump
)
1076 rtx cond
= if_info
->cond
;
1077 enum rtx_code code
= reversed_comparison_code (cond
, if_info
->jump
);
1079 /* First try to use addcc pattern. */
1080 if (general_operand (XEXP (cond
, 0), VOIDmode
)
1081 && general_operand (XEXP (cond
, 1), VOIDmode
))
1084 target
= emit_conditional_add (if_info
->x
, code
,
1089 XEXP (if_info
->a
, 1),
1090 GET_MODE (if_info
->x
),
1091 (code
== LTU
|| code
== GEU
1092 || code
== LEU
|| code
== GTU
));
1095 if (target
!= if_info
->x
)
1096 noce_emit_move_insn (if_info
->x
, target
);
1098 seq
= end_ifcvt_sequence (if_info
);
1102 emit_insn_before_setloc (seq
, if_info
->jump
,
1103 INSN_LOCATOR (if_info
->insn_a
));
1109 /* If that fails, construct conditional increment or decrement using
1111 if (BRANCH_COST
>= 2
1112 && (XEXP (if_info
->a
, 1) == const1_rtx
1113 || XEXP (if_info
->a
, 1) == constm1_rtx
))
1116 if (STORE_FLAG_VALUE
== INTVAL (XEXP (if_info
->a
, 1)))
1117 subtract
= 0, normalize
= 0;
1118 else if (-STORE_FLAG_VALUE
== INTVAL (XEXP (if_info
->a
, 1)))
1119 subtract
= 1, normalize
= 0;
1121 subtract
= 0, normalize
= INTVAL (XEXP (if_info
->a
, 1));
1124 target
= noce_emit_store_flag (if_info
,
1125 gen_reg_rtx (GET_MODE (if_info
->x
)),
1129 target
= expand_simple_binop (GET_MODE (if_info
->x
),
1130 subtract
? MINUS
: PLUS
,
1131 if_info
->b
, target
, if_info
->x
,
1135 if (target
!= if_info
->x
)
1136 noce_emit_move_insn (if_info
->x
, target
);
1138 seq
= end_ifcvt_sequence (if_info
);
1142 emit_insn_before_setloc (seq
, if_info
->jump
,
1143 INSN_LOCATOR (if_info
->insn_a
));
1153 /* Convert "if (test) x = 0;" to "x &= -(test == 0);" */
1156 noce_try_store_flag_mask (struct noce_if_info
*if_info
)
1162 if ((BRANCH_COST
>= 2
1163 || STORE_FLAG_VALUE
== -1)
1164 && ((if_info
->a
== const0_rtx
1165 && rtx_equal_p (if_info
->b
, if_info
->x
))
1166 || ((reversep
= (reversed_comparison_code (if_info
->cond
,
1169 && if_info
->b
== const0_rtx
1170 && rtx_equal_p (if_info
->a
, if_info
->x
))))
1173 target
= noce_emit_store_flag (if_info
,
1174 gen_reg_rtx (GET_MODE (if_info
->x
)),
1177 target
= expand_simple_binop (GET_MODE (if_info
->x
), AND
,
1179 target
, if_info
->x
, 0,
1184 if (target
!= if_info
->x
)
1185 noce_emit_move_insn (if_info
->x
, target
);
1187 seq
= end_ifcvt_sequence (if_info
);
1191 emit_insn_before_setloc (seq
, if_info
->jump
,
1192 INSN_LOCATOR (if_info
->insn_a
));
1202 /* Helper function for noce_try_cmove and noce_try_cmove_arith. */
1205 noce_emit_cmove (struct noce_if_info
*if_info
, rtx x
, enum rtx_code code
,
1206 rtx cmp_a
, rtx cmp_b
, rtx vfalse
, rtx vtrue
)
1208 /* If earliest == jump, try to build the cmove insn directly.
1209 This is helpful when combine has created some complex condition
1210 (like for alpha's cmovlbs) that we can't hope to regenerate
1211 through the normal interface. */
1213 if (if_info
->cond_earliest
== if_info
->jump
)
1217 tmp
= gen_rtx_fmt_ee (code
, GET_MODE (if_info
->cond
), cmp_a
, cmp_b
);
1218 tmp
= gen_rtx_IF_THEN_ELSE (GET_MODE (x
), tmp
, vtrue
, vfalse
);
1219 tmp
= gen_rtx_SET (VOIDmode
, x
, tmp
);
1222 tmp
= emit_insn (tmp
);
1224 if (recog_memoized (tmp
) >= 0)
1236 /* Don't even try if the comparison operands are weird. */
1237 if (! general_operand (cmp_a
, GET_MODE (cmp_a
))
1238 || ! general_operand (cmp_b
, GET_MODE (cmp_b
)))
1241 #if HAVE_conditional_move
1242 return emit_conditional_move (x
, code
, cmp_a
, cmp_b
, VOIDmode
,
1243 vtrue
, vfalse
, GET_MODE (x
),
1244 (code
== LTU
|| code
== GEU
1245 || code
== LEU
|| code
== GTU
));
1247 /* We'll never get here, as noce_process_if_block doesn't call the
1248 functions involved. Ifdef code, however, should be discouraged
1249 because it leads to typos in the code not selected. However,
1250 emit_conditional_move won't exist either. */
1255 /* Try only simple constants and registers here. More complex cases
1256 are handled in noce_try_cmove_arith after noce_try_store_flag_arith
1257 has had a go at it. */
1260 noce_try_cmove (struct noce_if_info
*if_info
)
1265 if ((CONSTANT_P (if_info
->a
) || register_operand (if_info
->a
, VOIDmode
))
1266 && (CONSTANT_P (if_info
->b
) || register_operand (if_info
->b
, VOIDmode
)))
1270 code
= GET_CODE (if_info
->cond
);
1271 target
= noce_emit_cmove (if_info
, if_info
->x
, code
,
1272 XEXP (if_info
->cond
, 0),
1273 XEXP (if_info
->cond
, 1),
1274 if_info
->a
, if_info
->b
);
1278 if (target
!= if_info
->x
)
1279 noce_emit_move_insn (if_info
->x
, target
);
1281 seq
= end_ifcvt_sequence (if_info
);
1285 emit_insn_before_setloc (seq
, if_info
->jump
,
1286 INSN_LOCATOR (if_info
->insn_a
));
1299 /* Try more complex cases involving conditional_move. */
1302 noce_try_cmove_arith (struct noce_if_info
*if_info
)
1314 /* A conditional move from two memory sources is equivalent to a
1315 conditional on their addresses followed by a load. Don't do this
1316 early because it'll screw alias analysis. Note that we've
1317 already checked for no side effects. */
1318 /* ??? FIXME: Magic number 5. */
1319 if (cse_not_expected
1320 && MEM_P (a
) && MEM_P (b
)
1321 && BRANCH_COST
>= 5)
1325 x
= gen_reg_rtx (Pmode
);
1329 /* ??? We could handle this if we knew that a load from A or B could
1330 not fault. This is also true if we've already loaded
1331 from the address along the path from ENTRY. */
1332 else if (may_trap_p (a
) || may_trap_p (b
))
1335 /* if (test) x = a + b; else x = c - d;
1342 code
= GET_CODE (if_info
->cond
);
1343 insn_a
= if_info
->insn_a
;
1344 insn_b
= if_info
->insn_b
;
1346 /* Total insn_rtx_cost should be smaller than branch cost. Exit
1347 if insn_rtx_cost can't be estimated. */
1350 insn_cost
= insn_rtx_cost (PATTERN (insn_a
));
1351 if (insn_cost
== 0 || insn_cost
> COSTS_N_INSNS (BRANCH_COST
))
1359 insn_cost
+= insn_rtx_cost (PATTERN (insn_b
));
1360 if (insn_cost
== 0 || insn_cost
> COSTS_N_INSNS (BRANCH_COST
))
1364 /* Possibly rearrange operands to make things come out more natural. */
1365 if (reversed_comparison_code (if_info
->cond
, if_info
->jump
) != UNKNOWN
)
1368 if (rtx_equal_p (b
, x
))
1370 else if (general_operand (b
, GET_MODE (b
)))
1375 code
= reversed_comparison_code (if_info
->cond
, if_info
->jump
);
1376 tmp
= a
, a
= b
, b
= tmp
;
1377 tmp
= insn_a
, insn_a
= insn_b
, insn_b
= tmp
;
1386 /* If either operand is complex, load it into a register first.
1387 The best way to do this is to copy the original insn. In this
1388 way we preserve any clobbers etc that the insn may have had.
1389 This is of course not possible in the IS_MEM case. */
1390 if (! general_operand (a
, GET_MODE (a
)))
1396 tmp
= gen_reg_rtx (GET_MODE (a
));
1397 tmp
= emit_insn (gen_rtx_SET (VOIDmode
, tmp
, a
));
1400 goto end_seq_and_fail
;
1403 a
= gen_reg_rtx (GET_MODE (a
));
1404 tmp
= copy_rtx (insn_a
);
1405 set
= single_set (tmp
);
1407 tmp
= emit_insn (PATTERN (tmp
));
1409 if (recog_memoized (tmp
) < 0)
1410 goto end_seq_and_fail
;
1412 if (! general_operand (b
, GET_MODE (b
)))
1418 tmp
= gen_reg_rtx (GET_MODE (b
));
1419 tmp
= gen_rtx_SET (VOIDmode
, tmp
, b
);
1422 goto end_seq_and_fail
;
1425 b
= gen_reg_rtx (GET_MODE (b
));
1426 tmp
= copy_rtx (insn_b
);
1427 set
= single_set (tmp
);
1429 tmp
= PATTERN (tmp
);
1432 /* If insn to set up A clobbers any registers B depends on, try to
1433 swap insn that sets up A with the one that sets up B. If even
1434 that doesn't help, punt. */
1435 last
= get_last_insn ();
1436 if (last
&& modified_in_p (orig_b
, last
))
1438 tmp
= emit_insn_before (tmp
, get_insns ());
1439 if (modified_in_p (orig_a
, tmp
))
1440 goto end_seq_and_fail
;
1443 tmp
= emit_insn (tmp
);
1445 if (recog_memoized (tmp
) < 0)
1446 goto end_seq_and_fail
;
1449 target
= noce_emit_cmove (if_info
, x
, code
, XEXP (if_info
->cond
, 0),
1450 XEXP (if_info
->cond
, 1), a
, b
);
1453 goto end_seq_and_fail
;
1455 /* If we're handling a memory for above, emit the load now. */
1458 tmp
= gen_rtx_MEM (GET_MODE (if_info
->x
), target
);
1460 /* Copy over flags as appropriate. */
1461 if (MEM_VOLATILE_P (if_info
->a
) || MEM_VOLATILE_P (if_info
->b
))
1462 MEM_VOLATILE_P (tmp
) = 1;
1463 if (MEM_IN_STRUCT_P (if_info
->a
) && MEM_IN_STRUCT_P (if_info
->b
))
1464 MEM_IN_STRUCT_P (tmp
) = 1;
1465 if (MEM_SCALAR_P (if_info
->a
) && MEM_SCALAR_P (if_info
->b
))
1466 MEM_SCALAR_P (tmp
) = 1;
1467 if (MEM_ALIAS_SET (if_info
->a
) == MEM_ALIAS_SET (if_info
->b
))
1468 set_mem_alias_set (tmp
, MEM_ALIAS_SET (if_info
->a
));
1470 MIN (MEM_ALIGN (if_info
->a
), MEM_ALIGN (if_info
->b
)));
1472 noce_emit_move_insn (if_info
->x
, tmp
);
1474 else if (target
!= x
)
1475 noce_emit_move_insn (x
, target
);
1477 tmp
= end_ifcvt_sequence (if_info
);
1481 emit_insn_before_setloc (tmp
, if_info
->jump
, INSN_LOCATOR (if_info
->insn_a
));
1489 /* For most cases, the simplified condition we found is the best
1490 choice, but this is not the case for the min/max/abs transforms.
1491 For these we wish to know that it is A or B in the condition. */
1494 noce_get_alt_condition (struct noce_if_info
*if_info
, rtx target
,
1497 rtx cond
, set
, insn
;
1500 /* If target is already mentioned in the known condition, return it. */
1501 if (reg_mentioned_p (target
, if_info
->cond
))
1503 *earliest
= if_info
->cond_earliest
;
1504 return if_info
->cond
;
1507 set
= pc_set (if_info
->jump
);
1508 cond
= XEXP (SET_SRC (set
), 0);
1510 = GET_CODE (XEXP (SET_SRC (set
), 2)) == LABEL_REF
1511 && XEXP (XEXP (SET_SRC (set
), 2), 0) == JUMP_LABEL (if_info
->jump
);
1512 if (if_info
->then_else_reversed
)
1515 /* If we're looking for a constant, try to make the conditional
1516 have that constant in it. There are two reasons why it may
1517 not have the constant we want:
1519 1. GCC may have needed to put the constant in a register, because
1520 the target can't compare directly against that constant. For
1521 this case, we look for a SET immediately before the comparison
1522 that puts a constant in that register.
1524 2. GCC may have canonicalized the conditional, for example
1525 replacing "if x < 4" with "if x <= 3". We can undo that (or
1526 make equivalent types of changes) to get the constants we need
1527 if they're off by one in the right direction. */
1529 if (GET_CODE (target
) == CONST_INT
)
1531 enum rtx_code code
= GET_CODE (if_info
->cond
);
1532 rtx op_a
= XEXP (if_info
->cond
, 0);
1533 rtx op_b
= XEXP (if_info
->cond
, 1);
1536 /* First, look to see if we put a constant in a register. */
1537 prev_insn
= prev_nonnote_insn (if_info
->cond_earliest
);
1539 && INSN_P (prev_insn
)
1540 && GET_CODE (PATTERN (prev_insn
)) == SET
)
1542 rtx src
= find_reg_equal_equiv_note (prev_insn
);
1544 src
= SET_SRC (PATTERN (prev_insn
));
1545 if (GET_CODE (src
) == CONST_INT
)
1547 if (rtx_equal_p (op_a
, SET_DEST (PATTERN (prev_insn
))))
1549 else if (rtx_equal_p (op_b
, SET_DEST (PATTERN (prev_insn
))))
1552 if (GET_CODE (op_a
) == CONST_INT
)
1557 code
= swap_condition (code
);
1562 /* Now, look to see if we can get the right constant by
1563 adjusting the conditional. */
1564 if (GET_CODE (op_b
) == CONST_INT
)
1566 HOST_WIDE_INT desired_val
= INTVAL (target
);
1567 HOST_WIDE_INT actual_val
= INTVAL (op_b
);
1572 if (actual_val
== desired_val
+ 1)
1575 op_b
= GEN_INT (desired_val
);
1579 if (actual_val
== desired_val
- 1)
1582 op_b
= GEN_INT (desired_val
);
1586 if (actual_val
== desired_val
- 1)
1589 op_b
= GEN_INT (desired_val
);
1593 if (actual_val
== desired_val
+ 1)
1596 op_b
= GEN_INT (desired_val
);
1604 /* If we made any changes, generate a new conditional that is
1605 equivalent to what we started with, but has the right
1607 if (code
!= GET_CODE (if_info
->cond
)
1608 || op_a
!= XEXP (if_info
->cond
, 0)
1609 || op_b
!= XEXP (if_info
->cond
, 1))
1611 cond
= gen_rtx_fmt_ee (code
, GET_MODE (cond
), op_a
, op_b
);
1612 *earliest
= if_info
->cond_earliest
;
1617 cond
= canonicalize_condition (if_info
->jump
, cond
, reverse
,
1618 earliest
, target
, false, true);
1619 if (! cond
|| ! reg_mentioned_p (target
, cond
))
1622 /* We almost certainly searched back to a different place.
1623 Need to re-verify correct lifetimes. */
1625 /* X may not be mentioned in the range (cond_earliest, jump]. */
1626 for (insn
= if_info
->jump
; insn
!= *earliest
; insn
= PREV_INSN (insn
))
1627 if (INSN_P (insn
) && reg_overlap_mentioned_p (if_info
->x
, PATTERN (insn
)))
1630 /* A and B may not be modified in the range [cond_earliest, jump). */
1631 for (insn
= *earliest
; insn
!= if_info
->jump
; insn
= NEXT_INSN (insn
))
1633 && (modified_in_p (if_info
->a
, insn
)
1634 || modified_in_p (if_info
->b
, insn
)))
1640 /* Convert "if (a < b) x = a; else x = b;" to "x = min(a, b);", etc. */
1643 noce_try_minmax (struct noce_if_info
*if_info
)
1645 rtx cond
, earliest
, target
, seq
;
1646 enum rtx_code code
, op
;
1649 /* ??? Reject modes with NaNs or signed zeros since we don't know how
1650 they will be resolved with an SMIN/SMAX. It wouldn't be too hard
1651 to get the target to tell us... */
1652 if (HONOR_SIGNED_ZEROS (GET_MODE (if_info
->x
))
1653 || HONOR_NANS (GET_MODE (if_info
->x
)))
1656 cond
= noce_get_alt_condition (if_info
, if_info
->a
, &earliest
);
1660 /* Verify the condition is of the form we expect, and canonicalize
1661 the comparison code. */
1662 code
= GET_CODE (cond
);
1663 if (rtx_equal_p (XEXP (cond
, 0), if_info
->a
))
1665 if (! rtx_equal_p (XEXP (cond
, 1), if_info
->b
))
1668 else if (rtx_equal_p (XEXP (cond
, 1), if_info
->a
))
1670 if (! rtx_equal_p (XEXP (cond
, 0), if_info
->b
))
1672 code
= swap_condition (code
);
1677 /* Determine what sort of operation this is. Note that the code is for
1678 a taken branch, so the code->operation mapping appears backwards. */
1711 target
= expand_simple_binop (GET_MODE (if_info
->x
), op
,
1712 if_info
->a
, if_info
->b
,
1713 if_info
->x
, unsignedp
, OPTAB_WIDEN
);
1719 if (target
!= if_info
->x
)
1720 noce_emit_move_insn (if_info
->x
, target
);
1722 seq
= end_ifcvt_sequence (if_info
);
1726 emit_insn_before_setloc (seq
, if_info
->jump
, INSN_LOCATOR (if_info
->insn_a
));
1727 if_info
->cond
= cond
;
1728 if_info
->cond_earliest
= earliest
;
1733 /* Convert "if (a < 0) x = -a; else x = a;" to "x = abs(a);", etc. */
1736 noce_try_abs (struct noce_if_info
*if_info
)
1738 rtx cond
, earliest
, target
, seq
, a
, b
, c
;
1741 /* Recognize A and B as constituting an ABS or NABS. The canonical
1742 form is a branch around the negation, taken when the object is the
1743 first operand of a comparison against 0 that evaluates to true. */
1746 if (GET_CODE (a
) == NEG
&& rtx_equal_p (XEXP (a
, 0), b
))
1748 else if (GET_CODE (b
) == NEG
&& rtx_equal_p (XEXP (b
, 0), a
))
1750 c
= a
; a
= b
; b
= c
;
1756 cond
= noce_get_alt_condition (if_info
, b
, &earliest
);
1760 /* Verify the condition is of the form we expect. */
1761 if (rtx_equal_p (XEXP (cond
, 0), b
))
1763 else if (rtx_equal_p (XEXP (cond
, 1), b
))
1771 /* Verify that C is zero. Search one step backward for a
1772 REG_EQUAL note or a simple source if necessary. */
1775 rtx set
, insn
= prev_nonnote_insn (earliest
);
1777 && (set
= single_set (insn
))
1778 && rtx_equal_p (SET_DEST (set
), c
))
1780 rtx note
= find_reg_equal_equiv_note (insn
);
1790 && GET_CODE (XEXP (c
, 0)) == SYMBOL_REF
1791 && CONSTANT_POOL_ADDRESS_P (XEXP (c
, 0)))
1792 c
= get_pool_constant (XEXP (c
, 0));
1794 /* Work around funny ideas get_condition has wrt canonicalization.
1795 Note that these rtx constants are known to be CONST_INT, and
1796 therefore imply integer comparisons. */
1797 if (c
== constm1_rtx
&& GET_CODE (cond
) == GT
)
1799 else if (c
== const1_rtx
&& GET_CODE (cond
) == LT
)
1801 else if (c
!= CONST0_RTX (GET_MODE (b
)))
1804 /* Determine what sort of operation this is. */
1805 switch (GET_CODE (cond
))
1824 target
= expand_abs_nojump (GET_MODE (if_info
->x
), b
, if_info
->x
, 1);
1826 /* ??? It's a quandary whether cmove would be better here, especially
1827 for integers. Perhaps combine will clean things up. */
1828 if (target
&& negate
)
1829 target
= expand_simple_unop (GET_MODE (target
), NEG
, target
, if_info
->x
, 0);
1837 if (target
!= if_info
->x
)
1838 noce_emit_move_insn (if_info
->x
, target
);
1840 seq
= end_ifcvt_sequence (if_info
);
1844 emit_insn_before_setloc (seq
, if_info
->jump
, INSN_LOCATOR (if_info
->insn_a
));
1845 if_info
->cond
= cond
;
1846 if_info
->cond_earliest
= earliest
;
1851 /* Convert "if (m < 0) x = b; else x = 0;" to "x = (m >> C) & b;". */
1854 noce_try_sign_mask (struct noce_if_info
*if_info
)
1856 rtx cond
, t
, m
, c
, seq
;
1857 enum machine_mode mode
;
1859 bool b_unconditional
;
1861 cond
= if_info
->cond
;
1862 code
= GET_CODE (cond
);
1867 if (if_info
->a
== const0_rtx
)
1869 if ((code
== LT
&& c
== const0_rtx
)
1870 || (code
== LE
&& c
== constm1_rtx
))
1873 else if (if_info
->b
== const0_rtx
)
1875 if ((code
== GE
&& c
== const0_rtx
)
1876 || (code
== GT
&& c
== constm1_rtx
))
1880 if (! t
|| side_effects_p (t
))
1883 /* We currently don't handle different modes. */
1884 mode
= GET_MODE (t
);
1885 if (GET_MODE (m
) != mode
)
1888 /* This is only profitable if T is cheap, or T is unconditionally
1889 executed/evaluated in the original insn sequence. The latter
1890 happens if INSN_B was taken from TEST_BB, or if there was no
1891 INSN_B which can happen for e.g. conditional stores to memory. */
1892 b_unconditional
= (if_info
->insn_b
== NULL_RTX
1893 || BLOCK_FOR_INSN (if_info
->insn_b
) == if_info
->test_bb
);
1894 if (rtx_cost (t
, SET
) >= COSTS_N_INSNS (2)
1895 && (!b_unconditional
1896 || t
!= if_info
->b
))
1900 /* Use emit_store_flag to generate "m < 0 ? -1 : 0" instead of expanding
1901 "(signed) m >> 31" directly. This benefits targets with specialized
1902 insns to obtain the signmask, but still uses ashr_optab otherwise. */
1903 m
= emit_store_flag (gen_reg_rtx (mode
), LT
, m
, const0_rtx
, mode
, 0, -1);
1904 t
= m
? expand_binop (mode
, and_optab
, m
, t
, NULL_RTX
, 0, OPTAB_DIRECT
)
1913 noce_emit_move_insn (if_info
->x
, t
);
1915 seq
= end_ifcvt_sequence (if_info
);
1919 emit_insn_before_setloc (seq
, if_info
->jump
, INSN_LOCATOR (if_info
->insn_a
));
1924 /* Optimize away "if (x & C) x |= C" and similar bit manipulation
1928 noce_try_bitop (struct noce_if_info
*if_info
)
1930 rtx cond
, x
, a
, result
, seq
;
1931 enum machine_mode mode
;
1936 cond
= if_info
->cond
;
1937 code
= GET_CODE (cond
);
1939 /* Check for no else condition. */
1940 if (! rtx_equal_p (x
, if_info
->b
))
1943 /* Check for a suitable condition. */
1944 if (code
!= NE
&& code
!= EQ
)
1946 if (XEXP (cond
, 1) != const0_rtx
)
1948 cond
= XEXP (cond
, 0);
1950 /* ??? We could also handle AND here. */
1951 if (GET_CODE (cond
) == ZERO_EXTRACT
)
1953 if (XEXP (cond
, 1) != const1_rtx
1954 || GET_CODE (XEXP (cond
, 2)) != CONST_INT
1955 || ! rtx_equal_p (x
, XEXP (cond
, 0)))
1957 bitnum
= INTVAL (XEXP (cond
, 2));
1958 mode
= GET_MODE (x
);
1959 if (BITS_BIG_ENDIAN
)
1960 bitnum
= GET_MODE_BITSIZE (mode
) - 1 - bitnum
;
1961 if (bitnum
< 0 || bitnum
>= HOST_BITS_PER_WIDE_INT
)
1968 if (GET_CODE (a
) == IOR
|| GET_CODE (a
) == XOR
)
1970 /* Check for "if (X & C) x = x op C". */
1971 if (! rtx_equal_p (x
, XEXP (a
, 0))
1972 || GET_CODE (XEXP (a
, 1)) != CONST_INT
1973 || (INTVAL (XEXP (a
, 1)) & GET_MODE_MASK (mode
))
1974 != (unsigned HOST_WIDE_INT
) 1 << bitnum
)
1977 /* if ((x & C) == 0) x |= C; is transformed to x |= C. */
1978 /* if ((x & C) != 0) x |= C; is transformed to nothing. */
1979 if (GET_CODE (a
) == IOR
)
1980 result
= (code
== NE
) ? a
: NULL_RTX
;
1981 else if (code
== NE
)
1983 /* if ((x & C) == 0) x ^= C; is transformed to x |= C. */
1984 result
= gen_int_mode ((HOST_WIDE_INT
) 1 << bitnum
, mode
);
1985 result
= simplify_gen_binary (IOR
, mode
, x
, result
);
1989 /* if ((x & C) != 0) x ^= C; is transformed to x &= ~C. */
1990 result
= gen_int_mode (~((HOST_WIDE_INT
) 1 << bitnum
), mode
);
1991 result
= simplify_gen_binary (AND
, mode
, x
, result
);
1994 else if (GET_CODE (a
) == AND
)
1996 /* Check for "if (X & C) x &= ~C". */
1997 if (! rtx_equal_p (x
, XEXP (a
, 0))
1998 || GET_CODE (XEXP (a
, 1)) != CONST_INT
1999 || (INTVAL (XEXP (a
, 1)) & GET_MODE_MASK (mode
))
2000 != (~((HOST_WIDE_INT
) 1 << bitnum
) & GET_MODE_MASK (mode
)))
2003 /* if ((x & C) == 0) x &= ~C; is transformed to nothing. */
2004 /* if ((x & C) != 0) x &= ~C; is transformed to x &= ~C. */
2005 result
= (code
== EQ
) ? a
: NULL_RTX
;
2013 noce_emit_move_insn (x
, result
);
2014 seq
= end_ifcvt_sequence (if_info
);
2018 emit_insn_before_setloc (seq
, if_info
->jump
,
2019 INSN_LOCATOR (if_info
->insn_a
));
2025 /* Similar to get_condition, only the resulting condition must be
2026 valid at JUMP, instead of at EARLIEST.
2028 If THEN_ELSE_REVERSED is true, the fallthrough does not go to the
2029 THEN block of the caller, and we have to reverse the condition. */
2032 noce_get_condition (rtx jump
, rtx
*earliest
, bool then_else_reversed
)
2037 if (! any_condjump_p (jump
))
2040 set
= pc_set (jump
);
2042 /* If this branches to JUMP_LABEL when the condition is false,
2043 reverse the condition. */
2044 reverse
= (GET_CODE (XEXP (SET_SRC (set
), 2)) == LABEL_REF
2045 && XEXP (XEXP (SET_SRC (set
), 2), 0) == JUMP_LABEL (jump
));
2047 /* We may have to reverse because the caller's if block is not canonical,
2048 i.e. the THEN block isn't the fallthrough block for the TEST block
2049 (see find_if_header). */
2050 if (then_else_reversed
)
2053 /* If the condition variable is a register and is MODE_INT, accept it. */
2055 cond
= XEXP (SET_SRC (set
), 0);
2056 tmp
= XEXP (cond
, 0);
2057 if (REG_P (tmp
) && GET_MODE_CLASS (GET_MODE (tmp
)) == MODE_INT
)
2062 cond
= gen_rtx_fmt_ee (reverse_condition (GET_CODE (cond
)),
2063 GET_MODE (cond
), tmp
, XEXP (cond
, 1));
2067 /* Otherwise, fall back on canonicalize_condition to do the dirty
2068 work of manipulating MODE_CC values and COMPARE rtx codes. */
2069 return canonicalize_condition (jump
, cond
, reverse
, earliest
,
2070 NULL_RTX
, false, true);
2073 /* Return true if OP is ok for if-then-else processing. */
2076 noce_operand_ok (rtx op
)
2078 /* We special-case memories, so handle any of them with
2079 no address side effects. */
2081 return ! side_effects_p (XEXP (op
, 0));
2083 if (side_effects_p (op
))
2086 return ! may_trap_p (op
);
2089 /* Return true if a write into MEM may trap or fault. */
2092 noce_mem_write_may_trap_or_fault_p (rtx mem
)
2096 if (MEM_READONLY_P (mem
))
2099 if (may_trap_or_fault_p (mem
))
2102 addr
= XEXP (mem
, 0);
2104 /* Call target hook to avoid the effects of -fpic etc.... */
2105 addr
= targetm
.delegitimize_address (addr
);
2108 switch (GET_CODE (addr
))
2116 addr
= XEXP (addr
, 0);
2120 addr
= XEXP (addr
, 1);
2123 if (GET_CODE (XEXP (addr
, 1)) == CONST_INT
)
2124 addr
= XEXP (addr
, 0);
2131 if (SYMBOL_REF_DECL (addr
)
2132 && decl_readonly_section (SYMBOL_REF_DECL (addr
), 0))
2142 /* Given a simple IF-THEN-JOIN or IF-THEN-ELSE-JOIN block, attempt to convert
2143 it without using conditional execution. Return TRUE if we were successful
2144 at converting the block. */
2147 noce_process_if_block (struct noce_if_info
*if_info
)
2149 basic_block test_bb
= if_info
->test_bb
; /* test block */
2150 basic_block then_bb
= if_info
->then_bb
; /* THEN */
2151 basic_block else_bb
= if_info
->else_bb
; /* ELSE or NULL */
2152 basic_block join_bb
= if_info
->join_bb
; /* JOIN */
2153 rtx jump
= if_info
->jump
;
2154 rtx cond
= if_info
->cond
;
2157 rtx orig_x
, x
, a
, b
;
2159 /* We're looking for patterns of the form
2161 (1) if (...) x = a; else x = b;
2162 (2) x = b; if (...) x = a;
2163 (3) if (...) x = a; // as if with an initial x = x.
2165 The later patterns require jumps to be more expensive.
2167 ??? For future expansion, look for multiple X in such patterns. */
2169 /* Look for one of the potential sets. */
2170 insn_a
= first_active_insn (then_bb
);
2172 || insn_a
!= last_active_insn (then_bb
, FALSE
)
2173 || (set_a
= single_set (insn_a
)) == NULL_RTX
)
2176 x
= SET_DEST (set_a
);
2177 a
= SET_SRC (set_a
);
2179 /* Look for the other potential set. Make sure we've got equivalent
2181 /* ??? This is overconservative. Storing to two different mems is
2182 as easy as conditionally computing the address. Storing to a
2183 single mem merely requires a scratch memory to use as one of the
2184 destination addresses; often the memory immediately below the
2185 stack pointer is available for this. */
2189 insn_b
= first_active_insn (else_bb
);
2191 || insn_b
!= last_active_insn (else_bb
, FALSE
)
2192 || (set_b
= single_set (insn_b
)) == NULL_RTX
2193 || ! rtx_equal_p (x
, SET_DEST (set_b
)))
2198 insn_b
= prev_nonnote_insn (if_info
->cond_earliest
);
2199 /* We're going to be moving the evaluation of B down from above
2200 COND_EARLIEST to JUMP. Make sure the relevant data is still
2203 || !NONJUMP_INSN_P (insn_b
)
2204 || (set_b
= single_set (insn_b
)) == NULL_RTX
2205 || ! rtx_equal_p (x
, SET_DEST (set_b
))
2206 || reg_overlap_mentioned_p (x
, SET_SRC (set_b
))
2207 || modified_between_p (SET_SRC (set_b
),
2208 PREV_INSN (if_info
->cond_earliest
), jump
)
2209 /* Likewise with X. In particular this can happen when
2210 noce_get_condition looks farther back in the instruction
2211 stream than one might expect. */
2212 || reg_overlap_mentioned_p (x
, cond
)
2213 || reg_overlap_mentioned_p (x
, a
)
2214 || modified_between_p (x
, PREV_INSN (if_info
->cond_earliest
), jump
))
2215 insn_b
= set_b
= NULL_RTX
;
2218 /* If x has side effects then only the if-then-else form is safe to
2219 convert. But even in that case we would need to restore any notes
2220 (such as REG_INC) at then end. That can be tricky if
2221 noce_emit_move_insn expands to more than one insn, so disable the
2222 optimization entirely for now if there are side effects. */
2223 if (side_effects_p (x
))
2226 b
= (set_b
? SET_SRC (set_b
) : x
);
2228 /* Only operate on register destinations, and even then avoid extending
2229 the lifetime of hard registers on small register class machines. */
2232 || (SMALL_REGISTER_CLASSES
2233 && REGNO (x
) < FIRST_PSEUDO_REGISTER
))
2235 if (GET_MODE (x
) == BLKmode
)
2238 if (GET_MODE (x
) == ZERO_EXTRACT
2239 && (GET_CODE (XEXP (x
, 1)) != CONST_INT
2240 || GET_CODE (XEXP (x
, 2)) != CONST_INT
))
2243 x
= gen_reg_rtx (GET_MODE (GET_CODE (x
) == STRICT_LOW_PART
2244 ? XEXP (x
, 0) : x
));
2247 /* Don't operate on sources that may trap or are volatile. */
2248 if (! noce_operand_ok (a
) || ! noce_operand_ok (b
))
2251 /* Set up the info block for our subroutines. */
2252 if_info
->insn_a
= insn_a
;
2253 if_info
->insn_b
= insn_b
;
2258 /* Try optimizations in some approximation of a useful order. */
2259 /* ??? Should first look to see if X is live incoming at all. If it
2260 isn't, we don't need anything but an unconditional set. */
2262 /* Look and see if A and B are really the same. Avoid creating silly
2263 cmove constructs that no one will fix up later. */
2264 if (rtx_equal_p (a
, b
))
2266 /* If we have an INSN_B, we don't have to create any new rtl. Just
2267 move the instruction that we already have. If we don't have an
2268 INSN_B, that means that A == X, and we've got a noop move. In
2269 that case don't do anything and let the code below delete INSN_A. */
2270 if (insn_b
&& else_bb
)
2274 if (else_bb
&& insn_b
== BB_END (else_bb
))
2275 BB_END (else_bb
) = PREV_INSN (insn_b
);
2276 reorder_insns (insn_b
, insn_b
, PREV_INSN (jump
));
2278 /* If there was a REG_EQUAL note, delete it since it may have been
2279 true due to this insn being after a jump. */
2280 if ((note
= find_reg_note (insn_b
, REG_EQUAL
, NULL_RTX
)) != 0)
2281 remove_note (insn_b
, note
);
2285 /* If we have "x = b; if (...) x = a;", and x has side-effects, then
2286 x must be executed twice. */
2287 else if (insn_b
&& side_effects_p (orig_x
))
2294 /* Disallow the "if (...) x = a;" form (with an implicit "else x = x;")
2295 for optimizations if writing to x may trap or fault, i.e. it's a memory
2296 other than a static var or a stack slot, is misaligned on strict
2297 aligned machines or is read-only.
2298 If x is a read-only memory, then the program is valid only if we
2299 avoid the store into it. If there are stores on both the THEN and
2300 ELSE arms, then we can go ahead with the conversion; either the
2301 program is broken, or the condition is always false such that the
2302 other memory is selected. */
2303 if (!set_b
&& MEM_P (orig_x
) && noce_mem_write_may_trap_or_fault_p (orig_x
))
2306 if (noce_try_move (if_info
))
2308 if (noce_try_store_flag (if_info
))
2310 if (noce_try_bitop (if_info
))
2312 if (noce_try_minmax (if_info
))
2314 if (noce_try_abs (if_info
))
2316 if (HAVE_conditional_move
2317 && noce_try_cmove (if_info
))
2319 if (! HAVE_conditional_execution
)
2321 if (noce_try_store_flag_constants (if_info
))
2323 if (noce_try_addcc (if_info
))
2325 if (noce_try_store_flag_mask (if_info
))
2327 if (HAVE_conditional_move
2328 && noce_try_cmove_arith (if_info
))
2330 if (noce_try_sign_mask (if_info
))
2338 /* If we used a temporary, fix it up now. */
2344 noce_emit_move_insn (orig_x
, x
);
2346 set_used_flags (orig_x
);
2347 unshare_all_rtl_in_chain (seq
);
2350 emit_insn_before_setloc (seq
, BB_END (test_bb
), INSN_LOCATOR (insn_a
));
2353 /* The original THEN and ELSE blocks may now be removed. The test block
2354 must now jump to the join block. If the test block and the join block
2355 can be merged, do so. */
2358 delete_basic_block (else_bb
);
2362 remove_edge (find_edge (test_bb
, join_bb
));
2364 remove_edge (find_edge (then_bb
, join_bb
));
2365 redirect_edge_and_branch_force (single_succ_edge (test_bb
), join_bb
);
2366 delete_basic_block (then_bb
);
2369 if (can_merge_blocks_p (test_bb
, join_bb
))
2371 merge_blocks (test_bb
, join_bb
);
2375 num_updated_if_blocks
++;
2379 /* Check whether a block is suitable for conditional move conversion.
2380 Every insn must be a simple set of a register to a constant or a
2381 register. For each assignment, store the value in the array VALS,
2382 indexed by register number, then store the register number in
2383 REGS. COND is the condition we will test. */
2386 check_cond_move_block (basic_block bb
, rtx
*vals
, VEC (int, heap
) *regs
, rtx cond
)
2390 /* We can only handle simple jumps at the end of the basic block.
2391 It is almost impossible to update the CFG otherwise. */
2393 if (JUMP_P (insn
) && !onlyjump_p (insn
))
2396 FOR_BB_INSNS (bb
, insn
)
2400 if (!INSN_P (insn
) || JUMP_P (insn
))
2402 set
= single_set (insn
);
2406 dest
= SET_DEST (set
);
2407 src
= SET_SRC (set
);
2409 || (SMALL_REGISTER_CLASSES
&& HARD_REGISTER_P (dest
)))
2412 if (!CONSTANT_P (src
) && !register_operand (src
, VOIDmode
))
2415 if (side_effects_p (src
) || side_effects_p (dest
))
2418 if (may_trap_p (src
) || may_trap_p (dest
))
2421 /* Don't try to handle this if the source register was
2422 modified earlier in the block. */
2424 && vals
[REGNO (src
)] != NULL
)
2425 || (GET_CODE (src
) == SUBREG
&& REG_P (SUBREG_REG (src
))
2426 && vals
[REGNO (SUBREG_REG (src
))] != NULL
))
2429 /* Don't try to handle this if the destination register was
2430 modified earlier in the block. */
2431 if (vals
[REGNO (dest
)] != NULL
)
2434 /* Don't try to handle this if the condition uses the
2435 destination register. */
2436 if (reg_overlap_mentioned_p (dest
, cond
))
2439 /* Don't try to handle this if the source register is modified
2440 later in the block. */
2441 if (!CONSTANT_P (src
)
2442 && modified_between_p (src
, insn
, NEXT_INSN (BB_END (bb
))))
2445 vals
[REGNO (dest
)] = src
;
2447 VEC_safe_push (int, heap
, regs
, REGNO (dest
));
2453 /* Given a basic block BB suitable for conditional move conversion,
2454 a condition COND, and arrays THEN_VALS and ELSE_VALS containing the
2455 register values depending on COND, emit the insns in the block as
2456 conditional moves. If ELSE_BLOCK is true, THEN_BB was already
2457 processed. The caller has started a sequence for the conversion.
2458 Return true if successful, false if something goes wrong. */
2461 cond_move_convert_if_block (struct noce_if_info
*if_infop
,
2462 basic_block bb
, rtx cond
,
2463 rtx
*then_vals
, rtx
*else_vals
,
2467 rtx insn
, cond_arg0
, cond_arg1
;
2469 code
= GET_CODE (cond
);
2470 cond_arg0
= XEXP (cond
, 0);
2471 cond_arg1
= XEXP (cond
, 1);
2473 FOR_BB_INSNS (bb
, insn
)
2475 rtx set
, target
, dest
, t
, e
;
2478 if (!INSN_P (insn
) || JUMP_P (insn
))
2480 set
= single_set (insn
);
2481 gcc_assert (set
&& REG_P (SET_DEST (set
)));
2483 dest
= SET_DEST (set
);
2484 regno
= REGNO (dest
);
2486 t
= then_vals
[regno
];
2487 e
= else_vals
[regno
];
2491 /* If this register was set in the then block, we already
2492 handled this case there. */
2505 target
= noce_emit_cmove (if_infop
, dest
, code
, cond_arg0
, cond_arg1
,
2511 noce_emit_move_insn (dest
, target
);
2517 /* Given a simple IF-THEN-JOIN or IF-THEN-ELSE-JOIN block, attempt to convert
2518 it using only conditional moves. Return TRUE if we were successful at
2519 converting the block. */
2522 cond_move_process_if_block (struct noce_if_info
*if_info
)
2524 basic_block test_bb
= if_info
->test_bb
;
2525 basic_block then_bb
= if_info
->then_bb
;
2526 basic_block else_bb
= if_info
->else_bb
;
2527 basic_block join_bb
= if_info
->join_bb
;
2528 rtx jump
= if_info
->jump
;
2529 rtx cond
= if_info
->cond
;
2531 int max_reg
, size
, c
, reg
;
2534 VEC (int, heap
) *then_regs
= NULL
;
2535 VEC (int, heap
) *else_regs
= NULL
;
2538 /* Build a mapping for each block to the value used for each
2540 max_reg
= max_reg_num ();
2541 size
= (max_reg
+ 1) * sizeof (rtx
);
2542 then_vals
= (rtx
*) alloca (size
);
2543 else_vals
= (rtx
*) alloca (size
);
2544 memset (then_vals
, 0, size
);
2545 memset (else_vals
, 0, size
);
2547 /* Make sure the blocks are suitable. */
2548 if (!check_cond_move_block (then_bb
, then_vals
, then_regs
, cond
)
2549 || (else_bb
&& !check_cond_move_block (else_bb
, else_vals
, else_regs
, cond
)))
2552 /* Make sure the blocks can be used together. If the same register
2553 is set in both blocks, and is not set to a constant in both
2554 cases, then both blocks must set it to the same register. We
2555 have already verified that if it is set to a register, that the
2556 source register does not change after the assignment. Also count
2557 the number of registers set in only one of the blocks. */
2559 for (i
= 0; VEC_iterate (int, then_regs
, i
, reg
); i
++)
2561 if (!then_vals
[reg
] && !else_vals
[reg
])
2564 if (!else_vals
[reg
])
2568 if (!CONSTANT_P (then_vals
[reg
])
2569 && !CONSTANT_P (else_vals
[reg
])
2570 && !rtx_equal_p (then_vals
[reg
], else_vals
[reg
]))
2575 /* Finish off c for MAX_CONDITIONAL_EXECUTE. */
2576 for (i
= 0; VEC_iterate (int, else_regs
, i
, reg
); ++i
)
2577 if (!then_vals
[reg
])
2580 /* Make sure it is reasonable to convert this block. What matters
2581 is the number of assignments currently made in only one of the
2582 branches, since if we convert we are going to always execute
2584 if (c
> MAX_CONDITIONAL_EXECUTE
)
2587 /* Try to emit the conditional moves. First do the then block,
2588 then do anything left in the else blocks. */
2590 if (!cond_move_convert_if_block (if_info
, then_bb
, cond
,
2591 then_vals
, else_vals
, false)
2593 && !cond_move_convert_if_block (if_info
, else_bb
, cond
,
2594 then_vals
, else_vals
, true)))
2599 seq
= end_ifcvt_sequence (if_info
);
2603 loc_insn
= first_active_insn (then_bb
);
2606 loc_insn
= first_active_insn (else_bb
);
2607 gcc_assert (loc_insn
);
2609 emit_insn_before_setloc (seq
, jump
, INSN_LOCATOR (loc_insn
));
2613 delete_basic_block (else_bb
);
2617 remove_edge (find_edge (test_bb
, join_bb
));
2619 remove_edge (find_edge (then_bb
, join_bb
));
2620 redirect_edge_and_branch_force (single_succ_edge (test_bb
), join_bb
);
2621 delete_basic_block (then_bb
);
2624 if (can_merge_blocks_p (test_bb
, join_bb
))
2626 merge_blocks (test_bb
, join_bb
);
2630 num_updated_if_blocks
++;
2632 VEC_free (int, heap
, then_regs
);
2633 VEC_free (int, heap
, else_regs
);
2639 /* Determine if a given basic block heads a simple IF-THEN-JOIN or an
2640 IF-THEN-ELSE-JOIN block.
2642 If so, we'll try to convert the insns to not require the branch,
2643 using only transformations that do not require conditional execution.
2645 Return TRUE if we were successful at converting the block. */
2648 noce_find_if_block (basic_block test_bb
,
2649 edge then_edge
, edge else_edge
,
2652 basic_block then_bb
, else_bb
, join_bb
;
2653 bool then_else_reversed
= false;
2655 struct noce_if_info if_info
;
2657 /* We only ever should get here before reload. */
2658 gcc_assert (!reload_completed
);
2660 /* Recognize an IF-THEN-ELSE-JOIN block. */
2661 if (single_pred_p (then_edge
->dest
)
2662 && single_succ_p (then_edge
->dest
)
2663 && single_pred_p (else_edge
->dest
)
2664 && single_succ_p (else_edge
->dest
)
2665 && single_succ (then_edge
->dest
) == single_succ (else_edge
->dest
))
2667 then_bb
= then_edge
->dest
;
2668 else_bb
= else_edge
->dest
;
2669 join_bb
= single_succ (then_bb
);
2671 /* Recognize an IF-THEN-JOIN block. */
2672 else if (single_pred_p (then_edge
->dest
)
2673 && single_succ_p (then_edge
->dest
)
2674 && single_succ (then_edge
->dest
) == else_edge
->dest
)
2676 then_bb
= then_edge
->dest
;
2677 else_bb
= NULL_BLOCK
;
2678 join_bb
= else_edge
->dest
;
2680 /* Recognize an IF-ELSE-JOIN block. We can have those because the order
2681 of basic blocks in cfglayout mode does not matter, so the fallthrough
2682 edge can go to any basic block (and not just to bb->next_bb, like in
2684 else if (single_pred_p (else_edge
->dest
)
2685 && single_succ_p (else_edge
->dest
)
2686 && single_succ (else_edge
->dest
) == then_edge
->dest
)
2688 /* The noce transformations do not apply to IF-ELSE-JOIN blocks.
2689 To make this work, we have to invert the THEN and ELSE blocks
2690 and reverse the jump condition. */
2691 then_bb
= else_edge
->dest
;
2692 else_bb
= NULL_BLOCK
;
2693 join_bb
= single_succ (then_bb
);
2694 then_else_reversed
= true;
2697 /* Not a form we can handle. */
2700 /* The edges of the THEN and ELSE blocks cannot have complex edges. */
2701 if (single_succ_edge (then_bb
)->flags
& EDGE_COMPLEX
)
2704 && single_succ_edge (else_bb
)->flags
& EDGE_COMPLEX
)
2707 num_possible_if_blocks
++;
2712 "\nIF-THEN%s-JOIN block found, pass %d, test %d, then %d",
2713 (else_bb
) ? "-ELSE" : "",
2714 pass
, test_bb
->index
, then_bb
->index
);
2717 fprintf (dump_file
, ", else %d", else_bb
->index
);
2719 fprintf (dump_file
, ", join %d\n", join_bb
->index
);
2722 /* If the conditional jump is more than just a conditional
2723 jump, then we can not do if-conversion on this block. */
2724 jump
= BB_END (test_bb
);
2725 if (! onlyjump_p (jump
))
2728 /* If this is not a standard conditional jump, we can't parse it. */
2729 cond
= noce_get_condition (jump
,
2730 &if_info
.cond_earliest
,
2731 then_else_reversed
);
2735 /* We must be comparing objects whose modes imply the size. */
2736 if (GET_MODE (XEXP (cond
, 0)) == BLKmode
)
2739 /* Initialize an IF_INFO struct to pass around. */
2740 memset (&if_info
, 0, sizeof if_info
);
2741 if_info
.test_bb
= test_bb
;
2742 if_info
.then_bb
= then_bb
;
2743 if_info
.else_bb
= else_bb
;
2744 if_info
.join_bb
= join_bb
;
2745 if_info
.cond
= cond
;
2746 if_info
.jump
= jump
;
2747 if_info
.then_else_reversed
= then_else_reversed
;
2749 /* Do the real work. */
2751 if (noce_process_if_block (&if_info
))
2754 if (HAVE_conditional_move
2755 && cond_move_process_if_block (&if_info
))
2762 /* Merge the blocks and mark for local life update. */
2765 merge_if_block (struct ce_if_block
* ce_info
)
2767 basic_block test_bb
= ce_info
->test_bb
; /* last test block */
2768 basic_block then_bb
= ce_info
->then_bb
; /* THEN */
2769 basic_block else_bb
= ce_info
->else_bb
; /* ELSE or NULL */
2770 basic_block join_bb
= ce_info
->join_bb
; /* join block */
2771 basic_block combo_bb
;
2773 /* All block merging is done into the lower block numbers. */
2777 /* Merge any basic blocks to handle && and || subtests. Each of
2778 the blocks are on the fallthru path from the predecessor block. */
2779 if (ce_info
->num_multiple_test_blocks
> 0)
2781 basic_block bb
= test_bb
;
2782 basic_block last_test_bb
= ce_info
->last_test_bb
;
2783 basic_block fallthru
= block_fallthru (bb
);
2788 fallthru
= block_fallthru (bb
);
2789 merge_blocks (combo_bb
, bb
);
2792 while (bb
!= last_test_bb
);
2795 /* Merge TEST block into THEN block. Normally the THEN block won't have a
2796 label, but it might if there were || tests. That label's count should be
2797 zero, and it normally should be removed. */
2801 merge_blocks (combo_bb
, then_bb
);
2805 /* The ELSE block, if it existed, had a label. That label count
2806 will almost always be zero, but odd things can happen when labels
2807 get their addresses taken. */
2810 merge_blocks (combo_bb
, else_bb
);
2814 /* If there was no join block reported, that means it was not adjacent
2815 to the others, and so we cannot merge them. */
2819 rtx last
= BB_END (combo_bb
);
2821 /* The outgoing edge for the current COMBO block should already
2822 be correct. Verify this. */
2823 if (EDGE_COUNT (combo_bb
->succs
) == 0)
2824 gcc_assert (find_reg_note (last
, REG_NORETURN
, NULL
)
2825 || (NONJUMP_INSN_P (last
)
2826 && GET_CODE (PATTERN (last
)) == TRAP_IF
2827 && (TRAP_CONDITION (PATTERN (last
))
2828 == const_true_rtx
)));
2831 /* There should still be something at the end of the THEN or ELSE
2832 blocks taking us to our final destination. */
2833 gcc_assert (JUMP_P (last
)
2834 || (EDGE_SUCC (combo_bb
, 0)->dest
== EXIT_BLOCK_PTR
2836 && SIBLING_CALL_P (last
))
2837 || ((EDGE_SUCC (combo_bb
, 0)->flags
& EDGE_EH
)
2838 && can_throw_internal (last
)));
2841 /* The JOIN block may have had quite a number of other predecessors too.
2842 Since we've already merged the TEST, THEN and ELSE blocks, we should
2843 have only one remaining edge from our if-then-else diamond. If there
2844 is more than one remaining edge, it must come from elsewhere. There
2845 may be zero incoming edges if the THEN block didn't actually join
2846 back up (as with a call to a non-return function). */
2847 else if (EDGE_COUNT (join_bb
->preds
) < 2
2848 && join_bb
!= EXIT_BLOCK_PTR
)
2850 /* We can merge the JOIN. */
2851 merge_blocks (combo_bb
, join_bb
);
2856 /* We cannot merge the JOIN. */
2858 /* The outgoing edge for the current COMBO block should already
2859 be correct. Verify this. */
2860 gcc_assert (single_succ_p (combo_bb
)
2861 && single_succ (combo_bb
) == join_bb
);
2863 /* Remove the jump and cruft from the end of the COMBO block. */
2864 if (join_bb
!= EXIT_BLOCK_PTR
)
2865 tidy_fallthru_edge (single_succ_edge (combo_bb
));
2868 num_updated_if_blocks
++;
2871 /* Find a block ending in a simple IF condition and try to transform it
2872 in some way. When converting a multi-block condition, put the new code
2873 in the first such block and delete the rest. Return a pointer to this
2874 first block if some transformation was done. Return NULL otherwise. */
2877 find_if_header (basic_block test_bb
, int pass
)
2879 ce_if_block_t ce_info
;
2883 /* The kind of block we're looking for has exactly two successors. */
2884 if (EDGE_COUNT (test_bb
->succs
) != 2)
2887 then_edge
= EDGE_SUCC (test_bb
, 0);
2888 else_edge
= EDGE_SUCC (test_bb
, 1);
2890 /* Neither edge should be abnormal. */
2891 if ((then_edge
->flags
& EDGE_COMPLEX
)
2892 || (else_edge
->flags
& EDGE_COMPLEX
))
2895 /* Nor exit the loop. */
2896 if ((then_edge
->flags
& EDGE_LOOP_EXIT
)
2897 || (else_edge
->flags
& EDGE_LOOP_EXIT
))
2900 /* The THEN edge is canonically the one that falls through. */
2901 if (then_edge
->flags
& EDGE_FALLTHRU
)
2903 else if (else_edge
->flags
& EDGE_FALLTHRU
)
2906 else_edge
= then_edge
;
2910 /* Otherwise this must be a multiway branch of some sort. */
2913 memset (&ce_info
, '\0', sizeof (ce_info
));
2914 ce_info
.test_bb
= test_bb
;
2915 ce_info
.then_bb
= then_edge
->dest
;
2916 ce_info
.else_bb
= else_edge
->dest
;
2917 ce_info
.pass
= pass
;
2919 #ifdef IFCVT_INIT_EXTRA_FIELDS
2920 IFCVT_INIT_EXTRA_FIELDS (&ce_info
);
2923 if (! reload_completed
2924 && noce_find_if_block (test_bb
, then_edge
, else_edge
, pass
))
2927 if (HAVE_conditional_execution
&& reload_completed
2928 && cond_exec_find_if_block (&ce_info
))
2931 if (HAVE_trap
&& HAVE_conditional_trap
2932 && find_cond_trap (test_bb
, then_edge
, else_edge
))
2935 if (dom_info_state (CDI_POST_DOMINATORS
) >= DOM_NO_FAST_QUERY
2936 && (! HAVE_conditional_execution
|| reload_completed
))
2938 if (find_if_case_1 (test_bb
, then_edge
, else_edge
))
2940 if (find_if_case_2 (test_bb
, then_edge
, else_edge
))
2948 fprintf (dump_file
, "Conversion succeeded on pass %d.\n", pass
);
2949 return ce_info
.test_bb
;
2952 /* Return true if a block has two edges, one of which falls through to the next
2953 block, and the other jumps to a specific block, so that we can tell if the
2954 block is part of an && test or an || test. Returns either -1 or the number
2955 of non-note, non-jump, non-USE/CLOBBER insns in the block. */
2958 block_jumps_and_fallthru_p (basic_block cur_bb
, basic_block target_bb
)
2961 int fallthru_p
= FALSE
;
2968 if (!cur_bb
|| !target_bb
)
2971 /* If no edges, obviously it doesn't jump or fallthru. */
2972 if (EDGE_COUNT (cur_bb
->succs
) == 0)
2975 FOR_EACH_EDGE (cur_edge
, ei
, cur_bb
->succs
)
2977 if (cur_edge
->flags
& EDGE_COMPLEX
)
2978 /* Anything complex isn't what we want. */
2981 else if (cur_edge
->flags
& EDGE_FALLTHRU
)
2984 else if (cur_edge
->dest
== target_bb
)
2991 if ((jump_p
& fallthru_p
) == 0)
2994 /* Don't allow calls in the block, since this is used to group && and ||
2995 together for conditional execution support. ??? we should support
2996 conditional execution support across calls for IA-64 some day, but
2997 for now it makes the code simpler. */
2998 end
= BB_END (cur_bb
);
2999 insn
= BB_HEAD (cur_bb
);
3001 while (insn
!= NULL_RTX
)
3008 && GET_CODE (PATTERN (insn
)) != USE
3009 && GET_CODE (PATTERN (insn
)) != CLOBBER
)
3015 insn
= NEXT_INSN (insn
);
3021 /* Determine if a given basic block heads a simple IF-THEN or IF-THEN-ELSE
3022 block. If so, we'll try to convert the insns to not require the branch.
3023 Return TRUE if we were successful at converting the block. */
3026 cond_exec_find_if_block (struct ce_if_block
* ce_info
)
3028 basic_block test_bb
= ce_info
->test_bb
;
3029 basic_block then_bb
= ce_info
->then_bb
;
3030 basic_block else_bb
= ce_info
->else_bb
;
3031 basic_block join_bb
= NULL_BLOCK
;
3036 ce_info
->last_test_bb
= test_bb
;
3038 /* We only ever should get here after reload,
3039 and only if we have conditional execution. */
3040 gcc_assert (HAVE_conditional_execution
&& reload_completed
);
3042 /* Discover if any fall through predecessors of the current test basic block
3043 were && tests (which jump to the else block) or || tests (which jump to
3045 if (single_pred_p (test_bb
)
3046 && single_pred_edge (test_bb
)->flags
== EDGE_FALLTHRU
)
3048 basic_block bb
= single_pred (test_bb
);
3049 basic_block target_bb
;
3050 int max_insns
= MAX_CONDITIONAL_EXECUTE
;
3053 /* Determine if the preceding block is an && or || block. */
3054 if ((n_insns
= block_jumps_and_fallthru_p (bb
, else_bb
)) >= 0)
3056 ce_info
->and_and_p
= TRUE
;
3057 target_bb
= else_bb
;
3059 else if ((n_insns
= block_jumps_and_fallthru_p (bb
, then_bb
)) >= 0)
3061 ce_info
->and_and_p
= FALSE
;
3062 target_bb
= then_bb
;
3065 target_bb
= NULL_BLOCK
;
3067 if (target_bb
&& n_insns
<= max_insns
)
3069 int total_insns
= 0;
3072 ce_info
->last_test_bb
= test_bb
;
3074 /* Found at least one && or || block, look for more. */
3077 ce_info
->test_bb
= test_bb
= bb
;
3078 total_insns
+= n_insns
;
3081 if (!single_pred_p (bb
))
3084 bb
= single_pred (bb
);
3085 n_insns
= block_jumps_and_fallthru_p (bb
, target_bb
);
3087 while (n_insns
>= 0 && (total_insns
+ n_insns
) <= max_insns
);
3089 ce_info
->num_multiple_test_blocks
= blocks
;
3090 ce_info
->num_multiple_test_insns
= total_insns
;
3092 if (ce_info
->and_and_p
)
3093 ce_info
->num_and_and_blocks
= blocks
;
3095 ce_info
->num_or_or_blocks
= blocks
;
3099 /* The THEN block of an IF-THEN combo must have exactly one predecessor,
3100 other than any || blocks which jump to the THEN block. */
3101 if ((EDGE_COUNT (then_bb
->preds
) - ce_info
->num_or_or_blocks
) != 1)
3104 /* The edges of the THEN and ELSE blocks cannot have complex edges. */
3105 FOR_EACH_EDGE (cur_edge
, ei
, then_bb
->preds
)
3107 if (cur_edge
->flags
& EDGE_COMPLEX
)
3111 FOR_EACH_EDGE (cur_edge
, ei
, else_bb
->preds
)
3113 if (cur_edge
->flags
& EDGE_COMPLEX
)
3117 /* The THEN block of an IF-THEN combo must have zero or one successors. */
3118 if (EDGE_COUNT (then_bb
->succs
) > 0
3119 && (!single_succ_p (then_bb
)
3120 || (single_succ_edge (then_bb
)->flags
& EDGE_COMPLEX
)
3121 || (flow2_completed
&& tablejump_p (BB_END (then_bb
), NULL
, NULL
))))
3124 /* If the THEN block has no successors, conditional execution can still
3125 make a conditional call. Don't do this unless the ELSE block has
3126 only one incoming edge -- the CFG manipulation is too ugly otherwise.
3127 Check for the last insn of the THEN block being an indirect jump, which
3128 is listed as not having any successors, but confuses the rest of the CE
3129 code processing. ??? we should fix this in the future. */
3130 if (EDGE_COUNT (then_bb
->succs
) == 0)
3132 if (single_pred_p (else_bb
))
3134 rtx last_insn
= BB_END (then_bb
);
3137 && NOTE_P (last_insn
)
3138 && last_insn
!= BB_HEAD (then_bb
))
3139 last_insn
= PREV_INSN (last_insn
);
3142 && JUMP_P (last_insn
)
3143 && ! simplejump_p (last_insn
))
3147 else_bb
= NULL_BLOCK
;
3153 /* If the THEN block's successor is the other edge out of the TEST block,
3154 then we have an IF-THEN combo without an ELSE. */
3155 else if (single_succ (then_bb
) == else_bb
)
3158 else_bb
= NULL_BLOCK
;
3161 /* If the THEN and ELSE block meet in a subsequent block, and the ELSE
3162 has exactly one predecessor and one successor, and the outgoing edge
3163 is not complex, then we have an IF-THEN-ELSE combo. */
3164 else if (single_succ_p (else_bb
)
3165 && single_succ (then_bb
) == single_succ (else_bb
)
3166 && single_pred_p (else_bb
)
3167 && ! (single_succ_edge (else_bb
)->flags
& EDGE_COMPLEX
)
3168 && ! (flow2_completed
&& tablejump_p (BB_END (else_bb
), NULL
, NULL
)))
3169 join_bb
= single_succ (else_bb
);
3171 /* Otherwise it is not an IF-THEN or IF-THEN-ELSE combination. */
3175 num_possible_if_blocks
++;
3180 "\nIF-THEN%s block found, pass %d, start block %d "
3181 "[insn %d], then %d [%d]",
3182 (else_bb
) ? "-ELSE" : "",
3185 BB_HEAD (test_bb
) ? (int)INSN_UID (BB_HEAD (test_bb
)) : -1,
3187 BB_HEAD (then_bb
) ? (int)INSN_UID (BB_HEAD (then_bb
)) : -1);
3190 fprintf (dump_file
, ", else %d [%d]",
3192 BB_HEAD (else_bb
) ? (int)INSN_UID (BB_HEAD (else_bb
)) : -1);
3194 fprintf (dump_file
, ", join %d [%d]",
3196 BB_HEAD (join_bb
) ? (int)INSN_UID (BB_HEAD (join_bb
)) : -1);
3198 if (ce_info
->num_multiple_test_blocks
> 0)
3199 fprintf (dump_file
, ", %d %s block%s last test %d [%d]",
3200 ce_info
->num_multiple_test_blocks
,
3201 (ce_info
->and_and_p
) ? "&&" : "||",
3202 (ce_info
->num_multiple_test_blocks
== 1) ? "" : "s",
3203 ce_info
->last_test_bb
->index
,
3204 ((BB_HEAD (ce_info
->last_test_bb
))
3205 ? (int)INSN_UID (BB_HEAD (ce_info
->last_test_bb
))
3208 fputc ('\n', dump_file
);
3211 /* Make sure IF, THEN, and ELSE, blocks are adjacent. Actually, we get the
3212 first condition for free, since we've already asserted that there's a
3213 fallthru edge from IF to THEN. Likewise for the && and || blocks, since
3214 we checked the FALLTHRU flag, those are already adjacent to the last IF
3216 /* ??? As an enhancement, move the ELSE block. Have to deal with
3217 BLOCK notes, if by no other means than backing out the merge if they
3218 exist. Sticky enough I don't want to think about it now. */
3220 if (else_bb
&& (next
= next
->next_bb
) != else_bb
)
3222 if ((next
= next
->next_bb
) != join_bb
&& join_bb
!= EXIT_BLOCK_PTR
)
3230 /* Do the real work. */
3232 ce_info
->else_bb
= else_bb
;
3233 ce_info
->join_bb
= join_bb
;
3235 /* If we have && and || tests, try to first handle combining the && and ||
3236 tests into the conditional code, and if that fails, go back and handle
3237 it without the && and ||, which at present handles the && case if there
3238 was no ELSE block. */
3239 if (cond_exec_process_if_block (ce_info
, TRUE
))
3242 if (ce_info
->num_multiple_test_blocks
)
3246 if (cond_exec_process_if_block (ce_info
, FALSE
))
3253 /* Convert a branch over a trap, or a branch
3254 to a trap, into a conditional trap. */
3257 find_cond_trap (basic_block test_bb
, edge then_edge
, edge else_edge
)
3259 basic_block then_bb
= then_edge
->dest
;
3260 basic_block else_bb
= else_edge
->dest
;
3261 basic_block other_bb
, trap_bb
;
3262 rtx trap
, jump
, cond
, cond_earliest
, seq
;
3265 /* Locate the block with the trap instruction. */
3266 /* ??? While we look for no successors, we really ought to allow
3267 EH successors. Need to fix merge_if_block for that to work. */
3268 if ((trap
= block_has_only_trap (then_bb
)) != NULL
)
3269 trap_bb
= then_bb
, other_bb
= else_bb
;
3270 else if ((trap
= block_has_only_trap (else_bb
)) != NULL
)
3271 trap_bb
= else_bb
, other_bb
= then_bb
;
3277 fprintf (dump_file
, "\nTRAP-IF block found, start %d, trap %d\n",
3278 test_bb
->index
, trap_bb
->index
);
3281 /* If this is not a standard conditional jump, we can't parse it. */
3282 jump
= BB_END (test_bb
);
3283 cond
= noce_get_condition (jump
, &cond_earliest
, false);
3287 /* If the conditional jump is more than just a conditional jump, then
3288 we can not do if-conversion on this block. */
3289 if (! onlyjump_p (jump
))
3292 /* We must be comparing objects whose modes imply the size. */
3293 if (GET_MODE (XEXP (cond
, 0)) == BLKmode
)
3296 /* Reverse the comparison code, if necessary. */
3297 code
= GET_CODE (cond
);
3298 if (then_bb
== trap_bb
)
3300 code
= reversed_comparison_code (cond
, jump
);
3301 if (code
== UNKNOWN
)
3305 /* Attempt to generate the conditional trap. */
3306 seq
= gen_cond_trap (code
, XEXP (cond
, 0),
3308 TRAP_CODE (PATTERN (trap
)));
3312 /* Emit the new insns before cond_earliest. */
3313 emit_insn_before_setloc (seq
, cond_earliest
, INSN_LOCATOR (trap
));
3315 /* Delete the trap block if possible. */
3316 remove_edge (trap_bb
== then_bb
? then_edge
: else_edge
);
3317 if (EDGE_COUNT (trap_bb
->preds
) == 0)
3319 delete_basic_block (trap_bb
);
3323 /* Wire together the blocks again. */
3324 if (current_ir_type () == IR_RTL_CFGLAYOUT
)
3325 single_succ_edge (test_bb
)->flags
|= EDGE_FALLTHRU
;
3330 lab
= JUMP_LABEL (jump
);
3331 newjump
= emit_jump_insn_after (gen_jump (lab
), jump
);
3332 LABEL_NUSES (lab
) += 1;
3333 JUMP_LABEL (newjump
) = lab
;
3334 emit_barrier_after (newjump
);
3338 if (can_merge_blocks_p (test_bb
, other_bb
))
3340 merge_blocks (test_bb
, other_bb
);
3344 num_updated_if_blocks
++;
3348 /* Subroutine of find_cond_trap: if BB contains only a trap insn,
3352 block_has_only_trap (basic_block bb
)
3356 /* We're not the exit block. */
3357 if (bb
== EXIT_BLOCK_PTR
)
3360 /* The block must have no successors. */
3361 if (EDGE_COUNT (bb
->succs
) > 0)
3364 /* The only instruction in the THEN block must be the trap. */
3365 trap
= first_active_insn (bb
);
3366 if (! (trap
== BB_END (bb
)
3367 && GET_CODE (PATTERN (trap
)) == TRAP_IF
3368 && TRAP_CONDITION (PATTERN (trap
)) == const_true_rtx
))
3374 /* Look for IF-THEN-ELSE cases in which one of THEN or ELSE is
3375 transformable, but not necessarily the other. There need be no
3378 Return TRUE if we were successful at converting the block.
3380 Cases we'd like to look at:
3383 if (test) goto over; // x not live
3391 if (! test) goto label;
3394 if (test) goto E; // x not live
3408 (3) // This one's really only interesting for targets that can do
3409 // multiway branching, e.g. IA-64 BBB bundles. For other targets
3410 // it results in multiple branches on a cache line, which often
3411 // does not sit well with predictors.
3413 if (test1) goto E; // predicted not taken
3429 (A) Don't do (2) if the branch is predicted against the block we're
3430 eliminating. Do it anyway if we can eliminate a branch; this requires
3431 that the sole successor of the eliminated block postdominate the other
3434 (B) With CE, on (3) we can steal from both sides of the if, creating
3443 Again, this is most useful if J postdominates.
3445 (C) CE substitutes for helpful life information.
3447 (D) These heuristics need a lot of work. */
3449 /* Tests for case 1 above. */
3452 find_if_case_1 (basic_block test_bb
, edge then_edge
, edge else_edge
)
3454 basic_block then_bb
= then_edge
->dest
;
3455 basic_block else_bb
= else_edge
->dest
, new_bb
;
3458 /* If we are partitioning hot/cold basic blocks, we don't want to
3459 mess up unconditional or indirect jumps that cross between hot
3462 Basic block partitioning may result in some jumps that appear to
3463 be optimizable (or blocks that appear to be mergeable), but which really
3464 must be left untouched (they are required to make it safely across
3465 partition boundaries). See the comments at the top of
3466 bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */
3468 if ((BB_END (then_bb
)
3469 && find_reg_note (BB_END (then_bb
), REG_CROSSING_JUMP
, NULL_RTX
))
3470 || (BB_END (test_bb
)
3471 && find_reg_note (BB_END (test_bb
), REG_CROSSING_JUMP
, NULL_RTX
))
3472 || (BB_END (else_bb
)
3473 && find_reg_note (BB_END (else_bb
), REG_CROSSING_JUMP
,
3477 /* THEN has one successor. */
3478 if (!single_succ_p (then_bb
))
3481 /* THEN does not fall through, but is not strange either. */
3482 if (single_succ_edge (then_bb
)->flags
& (EDGE_COMPLEX
| EDGE_FALLTHRU
))
3485 /* THEN has one predecessor. */
3486 if (!single_pred_p (then_bb
))
3489 /* THEN must do something. */
3490 if (forwarder_block_p (then_bb
))
3493 num_possible_if_blocks
++;
3496 "\nIF-CASE-1 found, start %d, then %d\n",
3497 test_bb
->index
, then_bb
->index
);
3499 /* THEN is small. */
3500 if (! cheap_bb_rtx_cost_p (then_bb
, COSTS_N_INSNS (BRANCH_COST
)))
3503 /* Registers set are dead, or are predicable. */
3504 if (! dead_or_predicable (test_bb
, then_bb
, else_bb
,
3505 single_succ (then_bb
), 1))
3508 /* Conversion went ok, including moving the insns and fixing up the
3509 jump. Adjust the CFG to match. */
3511 bitmap_ior (test_bb
->il
.rtl
->global_live_at_end
,
3512 else_bb
->il
.rtl
->global_live_at_start
,
3513 then_bb
->il
.rtl
->global_live_at_end
);
3516 /* We can avoid creating a new basic block if then_bb is immediately
3517 followed by else_bb, i.e. deleting then_bb allows test_bb to fall
3520 if (then_bb
->next_bb
== else_bb
3521 && then_bb
->prev_bb
== test_bb
3522 && else_bb
!= EXIT_BLOCK_PTR
)
3524 redirect_edge_succ (FALLTHRU_EDGE (test_bb
), else_bb
);
3528 new_bb
= redirect_edge_and_branch_force (FALLTHRU_EDGE (test_bb
),
3531 then_bb_index
= then_bb
->index
;
3532 delete_basic_block (then_bb
);
3534 /* Make rest of code believe that the newly created block is the THEN_BB
3535 block we removed. */
3538 new_bb
->index
= then_bb_index
;
3539 SET_BASIC_BLOCK (then_bb_index
, new_bb
);
3540 /* Since the fallthru edge was redirected from test_bb to new_bb,
3541 we need to ensure that new_bb is in the same partition as
3542 test bb (you can not fall through across section boundaries). */
3543 BB_COPY_PARTITION (new_bb
, test_bb
);
3545 /* We've possibly created jump to next insn, cleanup_cfg will solve that
3549 num_updated_if_blocks
++;
3554 /* Test for case 2 above. */
3557 find_if_case_2 (basic_block test_bb
, edge then_edge
, edge else_edge
)
3559 basic_block then_bb
= then_edge
->dest
;
3560 basic_block else_bb
= else_edge
->dest
;
3564 /* If we are partitioning hot/cold basic blocks, we don't want to
3565 mess up unconditional or indirect jumps that cross between hot
3568 Basic block partitioning may result in some jumps that appear to
3569 be optimizable (or blocks that appear to be mergeable), but which really
3570 must be left untouched (they are required to make it safely across
3571 partition boundaries). See the comments at the top of
3572 bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */
3574 if ((BB_END (then_bb
)
3575 && find_reg_note (BB_END (then_bb
), REG_CROSSING_JUMP
, NULL_RTX
))
3576 || (BB_END (test_bb
)
3577 && find_reg_note (BB_END (test_bb
), REG_CROSSING_JUMP
, NULL_RTX
))
3578 || (BB_END (else_bb
)
3579 && find_reg_note (BB_END (else_bb
), REG_CROSSING_JUMP
,
3583 /* ELSE has one successor. */
3584 if (!single_succ_p (else_bb
))
3587 else_succ
= single_succ_edge (else_bb
);
3589 /* ELSE outgoing edge is not complex. */
3590 if (else_succ
->flags
& EDGE_COMPLEX
)
3593 /* ELSE has one predecessor. */
3594 if (!single_pred_p (else_bb
))
3597 /* THEN is not EXIT. */
3598 if (then_bb
->index
< NUM_FIXED_BLOCKS
)
3601 /* ELSE is predicted or SUCC(ELSE) postdominates THEN. */
3602 note
= find_reg_note (BB_END (test_bb
), REG_BR_PROB
, NULL_RTX
);
3603 if (note
&& INTVAL (XEXP (note
, 0)) >= REG_BR_PROB_BASE
/ 2)
3605 else if (else_succ
->dest
->index
< NUM_FIXED_BLOCKS
3606 || dominated_by_p (CDI_POST_DOMINATORS
, then_bb
,
3612 num_possible_if_blocks
++;
3615 "\nIF-CASE-2 found, start %d, else %d\n",
3616 test_bb
->index
, else_bb
->index
);
3618 /* ELSE is small. */
3619 if (! cheap_bb_rtx_cost_p (else_bb
, COSTS_N_INSNS (BRANCH_COST
)))
3622 /* Registers set are dead, or are predicable. */
3623 if (! dead_or_predicable (test_bb
, else_bb
, then_bb
, else_succ
->dest
, 0))
3626 /* Conversion went ok, including moving the insns and fixing up the
3627 jump. Adjust the CFG to match. */
3629 bitmap_ior (test_bb
->il
.rtl
->global_live_at_end
,
3630 then_bb
->il
.rtl
->global_live_at_start
,
3631 else_bb
->il
.rtl
->global_live_at_end
);
3633 delete_basic_block (else_bb
);
3636 num_updated_if_blocks
++;
3638 /* ??? We may now fallthru from one of THEN's successors into a join
3639 block. Rerun cleanup_cfg? Examine things manually? Wait? */
3644 /* A subroutine of dead_or_predicable called through for_each_rtx.
3645 Return 1 if a memory is found. */
3648 find_memory (rtx
*px
, void *data ATTRIBUTE_UNUSED
)
3653 /* Used by the code above to perform the actual rtl transformations.
3654 Return TRUE if successful.
3656 TEST_BB is the block containing the conditional branch. MERGE_BB
3657 is the block containing the code to manipulate. NEW_DEST is the
3658 label TEST_BB should be branching to after the conversion.
3659 REVERSEP is true if the sense of the branch should be reversed. */
3662 dead_or_predicable (basic_block test_bb
, basic_block merge_bb
,
3663 basic_block other_bb
, basic_block new_dest
, int reversep
)
3665 rtx head
, end
, jump
, earliest
= NULL_RTX
, old_dest
, new_label
= NULL_RTX
;
3667 jump
= BB_END (test_bb
);
3669 /* Find the extent of the real code in the merge block. */
3670 head
= BB_HEAD (merge_bb
);
3671 end
= BB_END (merge_bb
);
3673 /* If merge_bb ends with a tablejump, predicating/moving insn's
3674 into test_bb and then deleting merge_bb will result in the jumptable
3675 that follows merge_bb being removed along with merge_bb and then we
3676 get an unresolved reference to the jumptable. */
3677 if (tablejump_p (end
, NULL
, NULL
))
3681 head
= NEXT_INSN (head
);
3686 head
= end
= NULL_RTX
;
3689 head
= NEXT_INSN (head
);
3696 head
= end
= NULL_RTX
;
3699 end
= PREV_INSN (end
);
3702 /* Disable handling dead code by conditional execution if the machine needs
3703 to do anything funny with the tests, etc. */
3704 #ifndef IFCVT_MODIFY_TESTS
3705 if (HAVE_conditional_execution
)
3707 /* In the conditional execution case, we have things easy. We know
3708 the condition is reversible. We don't have to check life info
3709 because we're going to conditionally execute the code anyway.
3710 All that's left is making sure the insns involved can actually
3715 cond
= cond_exec_get_condition (jump
);
3719 prob_val
= find_reg_note (jump
, REG_BR_PROB
, NULL_RTX
);
3721 prob_val
= XEXP (prob_val
, 0);
3725 enum rtx_code rev
= reversed_comparison_code (cond
, jump
);
3728 cond
= gen_rtx_fmt_ee (rev
, GET_MODE (cond
), XEXP (cond
, 0),
3731 prob_val
= GEN_INT (REG_BR_PROB_BASE
- INTVAL (prob_val
));
3734 if (! cond_exec_process_insns ((ce_if_block_t
*)0, head
, end
, cond
,
3743 /* In the non-conditional execution case, we have to verify that there
3744 are no trapping operations, no calls, no references to memory, and
3745 that any registers modified are dead at the branch site. */
3747 rtx insn
, cond
, prev
;
3748 regset merge_set
, tmp
, test_live
, test_set
;
3749 struct propagate_block_info
*pbi
;
3750 unsigned i
, fail
= 0;
3753 /* Check for no calls or trapping operations. */
3754 for (insn
= head
; ; insn
= NEXT_INSN (insn
))
3760 if (may_trap_p (PATTERN (insn
)))
3763 /* ??? Even non-trapping memories such as stack frame
3764 references must be avoided. For stores, we collect
3765 no lifetime info; for reads, we'd have to assert
3766 true_dependence false against every store in the
3768 if (for_each_rtx (&PATTERN (insn
), find_memory
, NULL
))
3775 if (! any_condjump_p (jump
))
3778 /* Find the extent of the conditional. */
3779 cond
= noce_get_condition (jump
, &earliest
, false);
3784 MERGE_SET = set of registers set in MERGE_BB
3785 TEST_LIVE = set of registers live at EARLIEST
3786 TEST_SET = set of registers set between EARLIEST and the
3787 end of the block. */
3789 tmp
= ALLOC_REG_SET (®_obstack
);
3790 merge_set
= ALLOC_REG_SET (®_obstack
);
3791 test_live
= ALLOC_REG_SET (®_obstack
);
3792 test_set
= ALLOC_REG_SET (®_obstack
);
3794 /* ??? bb->local_set is only valid during calculate_global_regs_live,
3795 so we must recompute usage for MERGE_BB. Not so bad, I suppose,
3796 since we've already asserted that MERGE_BB is small. */
3797 /* If we allocated new pseudos (e.g. in the conditional move
3798 expander called from noce_emit_cmove), we must resize the
3800 if (max_regno
< max_reg_num ())
3802 max_regno
= max_reg_num ();
3803 allocate_reg_info (max_regno
, FALSE
, FALSE
);
3805 propagate_block (merge_bb
, tmp
, merge_set
, merge_set
, 0);
3807 /* For small register class machines, don't lengthen lifetimes of
3808 hard registers before reload. */
3809 if (SMALL_REGISTER_CLASSES
&& ! reload_completed
)
3811 EXECUTE_IF_SET_IN_BITMAP (merge_set
, 0, i
, bi
)
3813 if (i
< FIRST_PSEUDO_REGISTER
3815 && ! global_regs
[i
])
3820 /* For TEST, we're interested in a range of insns, not a whole block.
3821 Moreover, we're interested in the insns live from OTHER_BB. */
3823 COPY_REG_SET (test_live
, other_bb
->il
.rtl
->global_live_at_start
);
3824 pbi
= init_propagate_block_info (test_bb
, test_live
, test_set
, test_set
,
3827 for (insn
= jump
; ; insn
= prev
)
3829 prev
= propagate_one_insn (pbi
, insn
);
3830 if (insn
== earliest
)
3834 free_propagate_block_info (pbi
);
3836 /* We can perform the transformation if
3837 MERGE_SET & (TEST_SET | TEST_LIVE)
3839 TEST_SET & merge_bb->il.rtl->global_live_at_start
3842 if (bitmap_intersect_p (test_set
, merge_set
)
3843 || bitmap_intersect_p (test_live
, merge_set
)
3844 || bitmap_intersect_p (test_set
,
3845 merge_bb
->il
.rtl
->global_live_at_start
))
3849 FREE_REG_SET (merge_set
);
3850 FREE_REG_SET (test_live
);
3851 FREE_REG_SET (test_set
);
3858 /* We don't want to use normal invert_jump or redirect_jump because
3859 we don't want to delete_insn called. Also, we want to do our own
3860 change group management. */
3862 old_dest
= JUMP_LABEL (jump
);
3863 if (other_bb
!= new_dest
)
3865 new_label
= block_label (new_dest
);
3867 ? ! invert_jump_1 (jump
, new_label
)
3868 : ! redirect_jump_1 (jump
, new_label
))
3872 if (! apply_change_group ())
3875 if (other_bb
!= new_dest
)
3877 redirect_jump_2 (jump
, old_dest
, new_label
, 0, reversep
);
3879 redirect_edge_succ (BRANCH_EDGE (test_bb
), new_dest
);
3882 gcov_type count
, probability
;
3883 count
= BRANCH_EDGE (test_bb
)->count
;
3884 BRANCH_EDGE (test_bb
)->count
= FALLTHRU_EDGE (test_bb
)->count
;
3885 FALLTHRU_EDGE (test_bb
)->count
= count
;
3886 probability
= BRANCH_EDGE (test_bb
)->probability
;
3887 BRANCH_EDGE (test_bb
)->probability
3888 = FALLTHRU_EDGE (test_bb
)->probability
;
3889 FALLTHRU_EDGE (test_bb
)->probability
= probability
;
3890 update_br_prob_note (test_bb
);
3894 /* Move the insns out of MERGE_BB to before the branch. */
3899 if (end
== BB_END (merge_bb
))
3900 BB_END (merge_bb
) = PREV_INSN (head
);
3902 /* PR 21767: When moving insns above a conditional branch, REG_EQUAL
3903 notes might become invalid. */
3909 if (! INSN_P (insn
))
3911 note
= find_reg_note (insn
, REG_EQUAL
, NULL_RTX
);
3914 set
= single_set (insn
);
3915 if (!set
|| !function_invariant_p (SET_SRC (set
)))
3916 remove_note (insn
, note
);
3917 } while (insn
!= end
&& (insn
= NEXT_INSN (insn
)));
3919 reorder_insns (head
, end
, PREV_INSN (earliest
));
3922 /* Remove the jump and edge if we can. */
3923 if (other_bb
== new_dest
)
3926 remove_edge (BRANCH_EDGE (test_bb
));
3927 /* ??? Can't merge blocks here, as then_bb is still in use.
3928 At minimum, the merge will get done just before bb-reorder. */
3938 /* Main entry point for all if-conversion. */
3941 if_convert (int x_life_data_ok
)
3946 num_possible_if_blocks
= 0;
3947 num_updated_if_blocks
= 0;
3948 num_true_changes
= 0;
3949 life_data_ok
= (x_life_data_ok
!= 0);
3951 /* Some transformations in this pass can create new pseudos,
3952 if the pass runs before reload. Make sure we can do so. */
3953 gcc_assert (! no_new_pseudos
|| reload_completed
);
3955 loop_optimizer_init (AVOID_CFG_MODIFICATIONS
);
3956 mark_loop_exit_edges ();
3957 loop_optimizer_finalize ();
3958 free_dominance_info (CDI_DOMINATORS
);
3960 /* Compute postdominators if we think we'll use them. */
3961 if (HAVE_conditional_execution
|| life_data_ok
)
3962 calculate_dominance_info (CDI_POST_DOMINATORS
);
3967 /* Go through each of the basic blocks looking for things to convert. If we
3968 have conditional execution, we make multiple passes to allow us to handle
3969 IF-THEN{-ELSE} blocks within other IF-THEN{-ELSE} blocks. */
3973 cond_exec_changed_p
= FALSE
;
3976 #ifdef IFCVT_MULTIPLE_DUMPS
3977 if (dump_file
&& pass
> 1)
3978 fprintf (dump_file
, "\n\n========== Pass %d ==========\n", pass
);
3984 while ((new_bb
= find_if_header (bb
, pass
)))
3988 #ifdef IFCVT_MULTIPLE_DUMPS
3989 if (dump_file
&& cond_exec_changed_p
)
3990 print_rtl_with_bb (dump_file
, get_insns ());
3993 while (cond_exec_changed_p
);
3995 #ifdef IFCVT_MULTIPLE_DUMPS
3997 fprintf (dump_file
, "\n\n========== no more changes\n");
4000 free_dominance_info (CDI_POST_DOMINATORS
);
4005 clear_aux_for_blocks ();
4007 /* Rebuild life info for basic blocks that require it. */
4008 if (num_true_changes
&& life_data_ok
)
4010 /* If we allocated new pseudos, we must resize the array for sched1. */
4011 if (max_regno
< max_reg_num ())
4013 max_regno
= max_reg_num ();
4014 allocate_reg_info (max_regno
, FALSE
, FALSE
);
4016 update_life_info_in_dirty_blocks (UPDATE_LIFE_GLOBAL_RM_NOTES
,
4017 PROP_DEATH_NOTES
| PROP_SCAN_DEAD_CODE
4018 | PROP_KILL_DEAD_CODE
);
4021 /* Write the final stats. */
4022 if (dump_file
&& num_possible_if_blocks
> 0)
4025 "\n%d possible IF blocks searched.\n",
4026 num_possible_if_blocks
);
4028 "%d IF blocks converted.\n",
4029 num_updated_if_blocks
);
4031 "%d true changes made.\n\n\n",
4035 #ifdef ENABLE_CHECKING
4036 verify_flow_info ();
4041 gate_handle_if_conversion (void)
4043 return (optimize
> 0);
4046 /* If-conversion and CFG cleanup. */
4048 rest_of_handle_if_conversion (void)
4050 if (flag_if_conversion
)
4053 dump_flow_info (dump_file
, dump_flags
);
4054 cleanup_cfg (CLEANUP_EXPENSIVE
);
4055 reg_scan (get_insns (), max_reg_num ());
4059 timevar_push (TV_JUMP
);
4060 cleanup_cfg (CLEANUP_EXPENSIVE
);
4061 reg_scan (get_insns (), max_reg_num ());
4062 timevar_pop (TV_JUMP
);
4066 struct tree_opt_pass pass_rtl_ifcvt
=
4069 gate_handle_if_conversion
, /* gate */
4070 rest_of_handle_if_conversion
, /* execute */
4073 0, /* static_pass_number */
4074 TV_IFCVT
, /* tv_id */
4075 0, /* properties_required */
4076 0, /* properties_provided */
4077 0, /* properties_destroyed */
4078 0, /* todo_flags_start */
4079 TODO_dump_func
, /* todo_flags_finish */
4084 gate_handle_if_after_combine (void)
4086 return (optimize
> 0 && flag_if_conversion
);
4090 /* Rerun if-conversion, as combine may have simplified things enough
4091 to now meet sequence length restrictions. */
4093 rest_of_handle_if_after_combine (void)
4101 struct tree_opt_pass pass_if_after_combine
=
4104 gate_handle_if_after_combine
, /* gate */
4105 rest_of_handle_if_after_combine
, /* execute */
4108 0, /* static_pass_number */
4109 TV_IFCVT
, /* tv_id */
4110 0, /* properties_required */
4111 0, /* properties_provided */
4112 0, /* properties_destroyed */
4113 0, /* todo_flags_start */
4115 TODO_ggc_collect
, /* todo_flags_finish */
4121 gate_handle_if_after_reload (void)
4123 return (optimize
> 0);
4127 rest_of_handle_if_after_reload (void)
4129 /* Last attempt to optimize CFG, as scheduling, peepholing and insn
4130 splitting possibly introduced more crossjumping opportunities. */
4131 cleanup_cfg (CLEANUP_EXPENSIVE
4132 | CLEANUP_UPDATE_LIFE
4133 | (flag_crossjumping
? CLEANUP_CROSSJUMP
: 0));
4134 if (flag_if_conversion2
)
4140 struct tree_opt_pass pass_if_after_reload
=
4143 gate_handle_if_after_reload
, /* gate */
4144 rest_of_handle_if_after_reload
, /* execute */
4147 0, /* static_pass_number */
4148 TV_IFCVT2
, /* tv_id */
4149 0, /* properties_required */
4150 0, /* properties_provided */
4151 0, /* properties_destroyed */
4152 0, /* todo_flags_start */
4154 TODO_ggc_collect
, /* todo_flags_finish */