1 /* If-conversion support.
2 Copyright (C) 2000, 2001, 2002, 2003, 2004, 2005
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, 59 Temple Place - Suite 330, Boston, MA
24 #include "coretypes.h"
31 #include "insn-config.h"
34 #include "hard-reg-set.h"
35 #include "basic-block.h"
46 #ifndef HAVE_conditional_execution
47 #define HAVE_conditional_execution 0
49 #ifndef HAVE_conditional_move
50 #define HAVE_conditional_move 0
61 #ifndef HAVE_conditional_trap
62 #define HAVE_conditional_trap 0
65 #ifndef MAX_CONDITIONAL_EXECUTE
66 #define MAX_CONDITIONAL_EXECUTE (BRANCH_COST + 1)
69 #define NULL_BLOCK ((basic_block) NULL)
71 /* # of IF-THEN or IF-THEN-ELSE blocks we looked at */
72 static int num_possible_if_blocks
;
74 /* # of IF-THEN or IF-THEN-ELSE blocks were converted to conditional
76 static int num_updated_if_blocks
;
78 /* # of changes made which require life information to be updated. */
79 static int num_true_changes
;
81 /* Whether conditional execution changes were made. */
82 static int cond_exec_changed_p
;
84 /* True if life data ok at present. */
85 static bool life_data_ok
;
87 /* Forward references. */
88 static int count_bb_insns (basic_block
);
89 static bool cheap_bb_rtx_cost_p (basic_block
, int);
90 static rtx
first_active_insn (basic_block
);
91 static rtx
last_active_insn (basic_block
, int);
92 static basic_block
block_fallthru (basic_block
);
93 static int cond_exec_process_insns (ce_if_block_t
*, rtx
, rtx
, rtx
, rtx
, int);
94 static rtx
cond_exec_get_condition (rtx
);
95 static int cond_exec_process_if_block (ce_if_block_t
*, int);
96 static rtx
noce_get_condition (rtx
, rtx
*);
97 static int noce_operand_ok (rtx
);
98 static int noce_process_if_block (ce_if_block_t
*);
99 static int process_if_block (ce_if_block_t
*);
100 static void merge_if_block (ce_if_block_t
*);
101 static int find_cond_trap (basic_block
, edge
, edge
);
102 static basic_block
find_if_header (basic_block
, int);
103 static int block_jumps_and_fallthru_p (basic_block
, basic_block
);
104 static int find_if_block (ce_if_block_t
*);
105 static int find_if_case_1 (basic_block
, edge
, edge
);
106 static int find_if_case_2 (basic_block
, edge
, edge
);
107 static int find_memory (rtx
*, void *);
108 static int dead_or_predicable (basic_block
, basic_block
, basic_block
,
110 static void noce_emit_move_insn (rtx
, rtx
);
111 static rtx
block_has_only_trap (basic_block
);
113 /* Count the number of non-jump active insns in BB. */
116 count_bb_insns (basic_block bb
)
119 rtx insn
= BB_HEAD (bb
);
123 if (CALL_P (insn
) || NONJUMP_INSN_P (insn
))
126 if (insn
== BB_END (bb
))
128 insn
= NEXT_INSN (insn
);
134 /* Determine whether the total insn_rtx_cost on non-jump insns in
135 basic block BB is less than MAX_COST. This function returns
136 false if the cost of any instruction could not be estimated. */
139 cheap_bb_rtx_cost_p (basic_block bb
, int max_cost
)
142 rtx insn
= BB_HEAD (bb
);
146 if (NONJUMP_INSN_P (insn
))
148 int cost
= insn_rtx_cost (PATTERN (insn
));
152 /* If this instruction is the load or set of a "stack" register,
153 such as a floating point register on x87, then the cost of
154 speculatively executing this instruction needs to include
155 the additional cost of popping this register off of the
159 rtx set
= single_set (insn
);
160 if (set
&& STACK_REG_P (SET_DEST (set
)))
161 cost
+= COSTS_N_INSNS (1);
166 if (count
>= max_cost
)
169 else if (CALL_P (insn
))
172 if (insn
== BB_END (bb
))
174 insn
= NEXT_INSN (insn
);
180 /* Return the first non-jump active insn in the basic block. */
183 first_active_insn (basic_block bb
)
185 rtx insn
= BB_HEAD (bb
);
189 if (insn
== BB_END (bb
))
191 insn
= NEXT_INSN (insn
);
194 while (NOTE_P (insn
))
196 if (insn
== BB_END (bb
))
198 insn
= NEXT_INSN (insn
);
207 /* Return the last non-jump active (non-jump) insn in the basic block. */
210 last_active_insn (basic_block bb
, int skip_use_p
)
212 rtx insn
= BB_END (bb
);
213 rtx head
= BB_HEAD (bb
);
218 && NONJUMP_INSN_P (insn
)
219 && GET_CODE (PATTERN (insn
)) == USE
))
223 insn
= PREV_INSN (insn
);
232 /* Return the basic block reached by falling though the basic block BB. */
235 block_fallthru (basic_block bb
)
240 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
241 if (e
->flags
& EDGE_FALLTHRU
)
244 return (e
) ? e
->dest
: NULL_BLOCK
;
247 /* Go through a bunch of insns, converting them to conditional
248 execution format if possible. Return TRUE if all of the non-note
249 insns were processed. */
252 cond_exec_process_insns (ce_if_block_t
*ce_info ATTRIBUTE_UNUSED
,
253 /* if block information */rtx start
,
254 /* first insn to look at */rtx end
,
255 /* last insn to look at */rtx test
,
256 /* conditional execution test */rtx prob_val
,
257 /* probability of branch taken. */int mod_ok
)
259 int must_be_last
= FALSE
;
267 for (insn
= start
; ; insn
= NEXT_INSN (insn
))
272 gcc_assert(NONJUMP_INSN_P (insn
) || CALL_P (insn
));
274 /* Remove USE insns that get in the way. */
275 if (reload_completed
&& GET_CODE (PATTERN (insn
)) == USE
)
277 /* ??? Ug. Actually unlinking the thing is problematic,
278 given what we'd have to coordinate with our callers. */
279 SET_INSN_DELETED (insn
);
283 /* Last insn wasn't last? */
287 if (modified_in_p (test
, insn
))
294 /* Now build the conditional form of the instruction. */
295 pattern
= PATTERN (insn
);
296 xtest
= copy_rtx (test
);
298 /* If this is already a COND_EXEC, rewrite the test to be an AND of the
300 if (GET_CODE (pattern
) == COND_EXEC
)
302 if (GET_MODE (xtest
) != GET_MODE (COND_EXEC_TEST (pattern
)))
305 xtest
= gen_rtx_AND (GET_MODE (xtest
), xtest
,
306 COND_EXEC_TEST (pattern
));
307 pattern
= COND_EXEC_CODE (pattern
);
310 pattern
= gen_rtx_COND_EXEC (VOIDmode
, xtest
, pattern
);
312 /* If the machine needs to modify the insn being conditionally executed,
313 say for example to force a constant integer operand into a temp
314 register, do so here. */
315 #ifdef IFCVT_MODIFY_INSN
316 IFCVT_MODIFY_INSN (ce_info
, pattern
, insn
);
321 validate_change (insn
, &PATTERN (insn
), pattern
, 1);
323 if (CALL_P (insn
) && prob_val
)
324 validate_change (insn
, ®_NOTES (insn
),
325 alloc_EXPR_LIST (REG_BR_PROB
, prob_val
,
326 REG_NOTES (insn
)), 1);
336 /* Return the condition for a jump. Do not do any special processing. */
339 cond_exec_get_condition (rtx jump
)
343 if (any_condjump_p (jump
))
344 test_if
= SET_SRC (pc_set (jump
));
347 cond
= XEXP (test_if
, 0);
349 /* If this branches to JUMP_LABEL when the condition is false,
350 reverse the condition. */
351 if (GET_CODE (XEXP (test_if
, 2)) == LABEL_REF
352 && XEXP (XEXP (test_if
, 2), 0) == JUMP_LABEL (jump
))
354 enum rtx_code rev
= reversed_comparison_code (cond
, jump
);
358 cond
= gen_rtx_fmt_ee (rev
, GET_MODE (cond
), XEXP (cond
, 0),
365 /* Given a simple IF-THEN or IF-THEN-ELSE block, attempt to convert it
366 to conditional execution. Return TRUE if we were successful at
367 converting the block. */
370 cond_exec_process_if_block (ce_if_block_t
* ce_info
,
371 /* if block information */int do_multiple_p
)
373 basic_block test_bb
= ce_info
->test_bb
; /* last test block */
374 basic_block then_bb
= ce_info
->then_bb
; /* THEN */
375 basic_block else_bb
= ce_info
->else_bb
; /* ELSE or NULL */
376 rtx test_expr
; /* expression in IF_THEN_ELSE that is tested */
377 rtx then_start
; /* first insn in THEN block */
378 rtx then_end
; /* last insn + 1 in THEN block */
379 rtx else_start
= NULL_RTX
; /* first insn in ELSE block or NULL */
380 rtx else_end
= NULL_RTX
; /* last insn + 1 in ELSE block */
381 int max
; /* max # of insns to convert. */
382 int then_mod_ok
; /* whether conditional mods are ok in THEN */
383 rtx true_expr
; /* test for else block insns */
384 rtx false_expr
; /* test for then block insns */
385 rtx true_prob_val
; /* probability of else block */
386 rtx false_prob_val
; /* probability of then block */
388 enum rtx_code false_code
;
390 /* If test is comprised of && or || elements, and we've failed at handling
391 all of them together, just use the last test if it is the special case of
392 && elements without an ELSE block. */
393 if (!do_multiple_p
&& ce_info
->num_multiple_test_blocks
)
395 if (else_bb
|| ! ce_info
->and_and_p
)
398 ce_info
->test_bb
= test_bb
= ce_info
->last_test_bb
;
399 ce_info
->num_multiple_test_blocks
= 0;
400 ce_info
->num_and_and_blocks
= 0;
401 ce_info
->num_or_or_blocks
= 0;
404 /* Find the conditional jump to the ELSE or JOIN part, and isolate
406 test_expr
= cond_exec_get_condition (BB_END (test_bb
));
410 /* If the conditional jump is more than just a conditional jump,
411 then we can not do conditional execution conversion on this block. */
412 if (! onlyjump_p (BB_END (test_bb
)))
415 /* Collect the bounds of where we're to search, skipping any labels, jumps
416 and notes at the beginning and end of the block. Then count the total
417 number of insns and see if it is small enough to convert. */
418 then_start
= first_active_insn (then_bb
);
419 then_end
= last_active_insn (then_bb
, TRUE
);
420 n_insns
= ce_info
->num_then_insns
= count_bb_insns (then_bb
);
421 max
= MAX_CONDITIONAL_EXECUTE
;
426 else_start
= first_active_insn (else_bb
);
427 else_end
= last_active_insn (else_bb
, TRUE
);
428 n_insns
+= ce_info
->num_else_insns
= count_bb_insns (else_bb
);
434 /* Map test_expr/test_jump into the appropriate MD tests to use on
435 the conditionally executed code. */
437 true_expr
= test_expr
;
439 false_code
= reversed_comparison_code (true_expr
, BB_END (test_bb
));
440 if (false_code
!= UNKNOWN
)
441 false_expr
= gen_rtx_fmt_ee (false_code
, GET_MODE (true_expr
),
442 XEXP (true_expr
, 0), XEXP (true_expr
, 1));
444 false_expr
= NULL_RTX
;
446 #ifdef IFCVT_MODIFY_TESTS
447 /* If the machine description needs to modify the tests, such as setting a
448 conditional execution register from a comparison, it can do so here. */
449 IFCVT_MODIFY_TESTS (ce_info
, true_expr
, false_expr
);
451 /* See if the conversion failed. */
452 if (!true_expr
|| !false_expr
)
456 true_prob_val
= find_reg_note (BB_END (test_bb
), REG_BR_PROB
, NULL_RTX
);
459 true_prob_val
= XEXP (true_prob_val
, 0);
460 false_prob_val
= GEN_INT (REG_BR_PROB_BASE
- INTVAL (true_prob_val
));
463 false_prob_val
= NULL_RTX
;
465 /* If we have && or || tests, do them here. These tests are in the adjacent
466 blocks after the first block containing the test. */
467 if (ce_info
->num_multiple_test_blocks
> 0)
469 basic_block bb
= test_bb
;
470 basic_block last_test_bb
= ce_info
->last_test_bb
;
479 enum rtx_code f_code
;
481 bb
= block_fallthru (bb
);
482 start
= first_active_insn (bb
);
483 end
= last_active_insn (bb
, TRUE
);
485 && ! cond_exec_process_insns (ce_info
, start
, end
, false_expr
,
486 false_prob_val
, FALSE
))
489 /* If the conditional jump is more than just a conditional jump, then
490 we can not do conditional execution conversion on this block. */
491 if (! onlyjump_p (BB_END (bb
)))
494 /* Find the conditional jump and isolate the test. */
495 t
= cond_exec_get_condition (BB_END (bb
));
499 f_code
= reversed_comparison_code (t
, BB_END (bb
));
500 if (f_code
== UNKNOWN
)
503 f
= gen_rtx_fmt_ee (f_code
, GET_MODE (t
), XEXP (t
, 0), XEXP (t
, 1));
504 if (ce_info
->and_and_p
)
506 t
= gen_rtx_AND (GET_MODE (t
), true_expr
, t
);
507 f
= gen_rtx_IOR (GET_MODE (t
), false_expr
, f
);
511 t
= gen_rtx_IOR (GET_MODE (t
), true_expr
, t
);
512 f
= gen_rtx_AND (GET_MODE (t
), false_expr
, f
);
515 /* If the machine description needs to modify the tests, such as
516 setting a conditional execution register from a comparison, it can
518 #ifdef IFCVT_MODIFY_MULTIPLE_TESTS
519 IFCVT_MODIFY_MULTIPLE_TESTS (ce_info
, bb
, t
, f
);
521 /* See if the conversion failed. */
529 while (bb
!= last_test_bb
);
532 /* For IF-THEN-ELSE blocks, we don't allow modifications of the test
533 on then THEN block. */
534 then_mod_ok
= (else_bb
== NULL_BLOCK
);
536 /* Go through the THEN and ELSE blocks converting the insns if possible
537 to conditional execution. */
541 || ! cond_exec_process_insns (ce_info
, then_start
, then_end
,
542 false_expr
, false_prob_val
,
546 if (else_bb
&& else_end
547 && ! cond_exec_process_insns (ce_info
, else_start
, else_end
,
548 true_expr
, true_prob_val
, TRUE
))
551 /* If we cannot apply the changes, fail. Do not go through the normal fail
552 processing, since apply_change_group will call cancel_changes. */
553 if (! apply_change_group ())
555 #ifdef IFCVT_MODIFY_CANCEL
556 /* Cancel any machine dependent changes. */
557 IFCVT_MODIFY_CANCEL (ce_info
);
562 #ifdef IFCVT_MODIFY_FINAL
563 /* Do any machine dependent final modifications. */
564 IFCVT_MODIFY_FINAL (ce_info
);
567 /* Conversion succeeded. */
569 fprintf (dump_file
, "%d insn%s converted to conditional execution.\n",
570 n_insns
, (n_insns
== 1) ? " was" : "s were");
572 /* Merge the blocks! */
573 merge_if_block (ce_info
);
574 cond_exec_changed_p
= TRUE
;
578 #ifdef IFCVT_MODIFY_CANCEL
579 /* Cancel any machine dependent changes. */
580 IFCVT_MODIFY_CANCEL (ce_info
);
587 /* Used by noce_process_if_block to communicate with its subroutines.
589 The subroutines know that A and B may be evaluated freely. They
590 know that X is a register. They should insert new instructions
591 before cond_earliest. */
598 rtx jump
, cond
, cond_earliest
;
599 /* True if "b" was originally evaluated unconditionally. */
600 bool b_unconditional
;
603 static rtx
noce_emit_store_flag (struct noce_if_info
*, rtx
, int, int);
604 static int noce_try_move (struct noce_if_info
*);
605 static int noce_try_store_flag (struct noce_if_info
*);
606 static int noce_try_addcc (struct noce_if_info
*);
607 static int noce_try_store_flag_constants (struct noce_if_info
*);
608 static int noce_try_store_flag_mask (struct noce_if_info
*);
609 static rtx
noce_emit_cmove (struct noce_if_info
*, rtx
, enum rtx_code
, rtx
,
611 static int noce_try_cmove (struct noce_if_info
*);
612 static int noce_try_cmove_arith (struct noce_if_info
*);
613 static rtx
noce_get_alt_condition (struct noce_if_info
*, rtx
, rtx
*);
614 static int noce_try_minmax (struct noce_if_info
*);
615 static int noce_try_abs (struct noce_if_info
*);
616 static int noce_try_sign_mask (struct noce_if_info
*);
618 /* Helper function for noce_try_store_flag*. */
621 noce_emit_store_flag (struct noce_if_info
*if_info
, rtx x
, int reversep
,
624 rtx cond
= if_info
->cond
;
628 cond_complex
= (! general_operand (XEXP (cond
, 0), VOIDmode
)
629 || ! general_operand (XEXP (cond
, 1), VOIDmode
));
631 /* If earliest == jump, or when the condition is complex, try to
632 build the store_flag insn directly. */
635 cond
= XEXP (SET_SRC (pc_set (if_info
->jump
)), 0);
638 code
= reversed_comparison_code (cond
, if_info
->jump
);
640 code
= GET_CODE (cond
);
642 if ((if_info
->cond_earliest
== if_info
->jump
|| cond_complex
)
643 && (normalize
== 0 || STORE_FLAG_VALUE
== normalize
))
647 tmp
= gen_rtx_fmt_ee (code
, GET_MODE (x
), XEXP (cond
, 0),
649 tmp
= gen_rtx_SET (VOIDmode
, x
, tmp
);
652 tmp
= emit_insn (tmp
);
654 if (recog_memoized (tmp
) >= 0)
660 if_info
->cond_earliest
= if_info
->jump
;
668 /* Don't even try if the comparison operands or the mode of X are weird. */
669 if (cond_complex
|| !SCALAR_INT_MODE_P (GET_MODE (x
)))
672 return emit_store_flag (x
, code
, XEXP (cond
, 0),
673 XEXP (cond
, 1), VOIDmode
,
674 (code
== LTU
|| code
== LEU
675 || code
== GEU
|| code
== GTU
), normalize
);
678 /* Emit instruction to move an rtx, possibly into STRICT_LOW_PART.
679 X is the destination/target and Y is the value to copy. */
682 noce_emit_move_insn (rtx x
, rtx y
)
684 enum machine_mode outmode
;
688 if (GET_CODE (x
) != STRICT_LOW_PART
)
690 emit_move_insn (x
, y
);
695 inner
= XEXP (outer
, 0);
696 outmode
= GET_MODE (outer
);
697 bitpos
= SUBREG_BYTE (outer
) * BITS_PER_UNIT
;
698 store_bit_field (inner
, GET_MODE_BITSIZE (outmode
), bitpos
, outmode
, y
);
701 /* Return sequence of instructions generated by if conversion. This
702 function calls end_sequence() to end the current stream, ensures
703 that are instructions are unshared, recognizable non-jump insns.
704 On failure, this function returns a NULL_RTX. */
707 end_ifcvt_sequence (struct noce_if_info
*if_info
)
710 rtx seq
= get_insns ();
712 set_used_flags (if_info
->x
);
713 set_used_flags (if_info
->cond
);
714 unshare_all_rtl_in_chain (seq
);
717 /* Make sure that all of the instructions emitted are recognizable,
718 and that we haven't introduced a new jump instruction.
719 As an exercise for the reader, build a general mechanism that
720 allows proper placement of required clobbers. */
721 for (insn
= seq
; insn
; insn
= NEXT_INSN (insn
))
723 || recog_memoized (insn
) == -1)
729 /* Convert "if (a != b) x = a; else x = b" into "x = a" and
730 "if (a == b) x = a; else x = b" into "x = b". */
733 noce_try_move (struct noce_if_info
*if_info
)
735 rtx cond
= if_info
->cond
;
736 enum rtx_code code
= GET_CODE (cond
);
739 if (code
!= NE
&& code
!= EQ
)
742 /* This optimization isn't valid if either A or B could be a NaN
744 if (HONOR_NANS (GET_MODE (if_info
->x
))
745 || HONOR_SIGNED_ZEROS (GET_MODE (if_info
->x
)))
748 /* Check whether the operands of the comparison are A and in
750 if ((rtx_equal_p (if_info
->a
, XEXP (cond
, 0))
751 && rtx_equal_p (if_info
->b
, XEXP (cond
, 1)))
752 || (rtx_equal_p (if_info
->a
, XEXP (cond
, 1))
753 && rtx_equal_p (if_info
->b
, XEXP (cond
, 0))))
755 y
= (code
== EQ
) ? if_info
->a
: if_info
->b
;
757 /* Avoid generating the move if the source is the destination. */
758 if (! rtx_equal_p (if_info
->x
, y
))
761 noce_emit_move_insn (if_info
->x
, y
);
762 seq
= end_ifcvt_sequence (if_info
);
766 emit_insn_before_setloc (seq
, if_info
->jump
,
767 INSN_LOCATOR (if_info
->insn_a
));
774 /* Convert "if (test) x = 1; else x = 0".
776 Only try 0 and STORE_FLAG_VALUE here. Other combinations will be
777 tried in noce_try_store_flag_constants after noce_try_cmove has had
778 a go at the conversion. */
781 noce_try_store_flag (struct noce_if_info
*if_info
)
786 if (GET_CODE (if_info
->b
) == CONST_INT
787 && INTVAL (if_info
->b
) == STORE_FLAG_VALUE
788 && if_info
->a
== const0_rtx
)
790 else if (if_info
->b
== const0_rtx
791 && GET_CODE (if_info
->a
) == CONST_INT
792 && INTVAL (if_info
->a
) == STORE_FLAG_VALUE
793 && (reversed_comparison_code (if_info
->cond
, if_info
->jump
)
801 target
= noce_emit_store_flag (if_info
, if_info
->x
, reversep
, 0);
804 if (target
!= if_info
->x
)
805 noce_emit_move_insn (if_info
->x
, target
);
807 seq
= end_ifcvt_sequence (if_info
);
811 emit_insn_before_setloc (seq
, if_info
->jump
,
812 INSN_LOCATOR (if_info
->insn_a
));
822 /* Convert "if (test) x = a; else x = b", for A and B constant. */
825 noce_try_store_flag_constants (struct noce_if_info
*if_info
)
829 HOST_WIDE_INT itrue
, ifalse
, diff
, tmp
;
830 int normalize
, can_reverse
;
831 enum machine_mode mode
;
834 && GET_CODE (if_info
->a
) == CONST_INT
835 && GET_CODE (if_info
->b
) == CONST_INT
)
837 mode
= GET_MODE (if_info
->x
);
838 ifalse
= INTVAL (if_info
->a
);
839 itrue
= INTVAL (if_info
->b
);
841 /* Make sure we can represent the difference between the two values. */
842 if ((itrue
- ifalse
> 0)
843 != ((ifalse
< 0) != (itrue
< 0) ? ifalse
< 0 : ifalse
< itrue
))
846 diff
= trunc_int_for_mode (itrue
- ifalse
, mode
);
848 can_reverse
= (reversed_comparison_code (if_info
->cond
, if_info
->jump
)
852 if (diff
== STORE_FLAG_VALUE
|| diff
== -STORE_FLAG_VALUE
)
854 else if (ifalse
== 0 && exact_log2 (itrue
) >= 0
855 && (STORE_FLAG_VALUE
== 1
856 || BRANCH_COST
>= 2))
858 else if (itrue
== 0 && exact_log2 (ifalse
) >= 0 && can_reverse
859 && (STORE_FLAG_VALUE
== 1 || BRANCH_COST
>= 2))
860 normalize
= 1, reversep
= 1;
862 && (STORE_FLAG_VALUE
== -1
863 || BRANCH_COST
>= 2))
865 else if (ifalse
== -1 && can_reverse
866 && (STORE_FLAG_VALUE
== -1 || BRANCH_COST
>= 2))
867 normalize
= -1, reversep
= 1;
868 else if ((BRANCH_COST
>= 2 && STORE_FLAG_VALUE
== -1)
876 tmp
= itrue
; itrue
= ifalse
; ifalse
= tmp
;
877 diff
= trunc_int_for_mode (-diff
, mode
);
881 target
= noce_emit_store_flag (if_info
, if_info
->x
, reversep
, normalize
);
888 /* if (test) x = 3; else x = 4;
889 => x = 3 + (test == 0); */
890 if (diff
== STORE_FLAG_VALUE
|| diff
== -STORE_FLAG_VALUE
)
892 target
= expand_simple_binop (mode
,
893 (diff
== STORE_FLAG_VALUE
895 GEN_INT (ifalse
), target
, if_info
->x
, 0,
899 /* if (test) x = 8; else x = 0;
900 => x = (test != 0) << 3; */
901 else if (ifalse
== 0 && (tmp
= exact_log2 (itrue
)) >= 0)
903 target
= expand_simple_binop (mode
, ASHIFT
,
904 target
, GEN_INT (tmp
), if_info
->x
, 0,
908 /* if (test) x = -1; else x = b;
909 => x = -(test != 0) | b; */
910 else if (itrue
== -1)
912 target
= expand_simple_binop (mode
, IOR
,
913 target
, GEN_INT (ifalse
), if_info
->x
, 0,
917 /* if (test) x = a; else x = b;
918 => x = (-(test != 0) & (b - a)) + a; */
921 target
= expand_simple_binop (mode
, AND
,
922 target
, GEN_INT (diff
), if_info
->x
, 0,
925 target
= expand_simple_binop (mode
, PLUS
,
926 target
, GEN_INT (ifalse
),
927 if_info
->x
, 0, OPTAB_WIDEN
);
936 if (target
!= if_info
->x
)
937 noce_emit_move_insn (if_info
->x
, target
);
939 seq
= end_ifcvt_sequence (if_info
);
943 emit_insn_before_setloc (seq
, if_info
->jump
,
944 INSN_LOCATOR (if_info
->insn_a
));
951 /* Convert "if (test) foo++" into "foo += (test != 0)", and
952 similarly for "foo--". */
955 noce_try_addcc (struct noce_if_info
*if_info
)
958 int subtract
, normalize
;
961 && GET_CODE (if_info
->a
) == PLUS
962 && rtx_equal_p (XEXP (if_info
->a
, 0), if_info
->b
)
963 && (reversed_comparison_code (if_info
->cond
, if_info
->jump
)
966 rtx cond
= if_info
->cond
;
967 enum rtx_code code
= reversed_comparison_code (cond
, if_info
->jump
);
969 /* First try to use addcc pattern. */
970 if (general_operand (XEXP (cond
, 0), VOIDmode
)
971 && general_operand (XEXP (cond
, 1), VOIDmode
))
974 target
= emit_conditional_add (if_info
->x
, code
,
979 XEXP (if_info
->a
, 1),
980 GET_MODE (if_info
->x
),
981 (code
== LTU
|| code
== GEU
982 || code
== LEU
|| code
== GTU
));
985 if (target
!= if_info
->x
)
986 noce_emit_move_insn (if_info
->x
, target
);
988 seq
= end_ifcvt_sequence (if_info
);
992 emit_insn_before_setloc (seq
, if_info
->jump
,
993 INSN_LOCATOR (if_info
->insn_a
));
999 /* If that fails, construct conditional increment or decrement using
1001 if (BRANCH_COST
>= 2
1002 && (XEXP (if_info
->a
, 1) == const1_rtx
1003 || XEXP (if_info
->a
, 1) == constm1_rtx
))
1006 if (STORE_FLAG_VALUE
== INTVAL (XEXP (if_info
->a
, 1)))
1007 subtract
= 0, normalize
= 0;
1008 else if (-STORE_FLAG_VALUE
== INTVAL (XEXP (if_info
->a
, 1)))
1009 subtract
= 1, normalize
= 0;
1011 subtract
= 0, normalize
= INTVAL (XEXP (if_info
->a
, 1));
1014 target
= noce_emit_store_flag (if_info
,
1015 gen_reg_rtx (GET_MODE (if_info
->x
)),
1019 target
= expand_simple_binop (GET_MODE (if_info
->x
),
1020 subtract
? MINUS
: PLUS
,
1021 if_info
->b
, target
, if_info
->x
,
1025 if (target
!= if_info
->x
)
1026 noce_emit_move_insn (if_info
->x
, target
);
1028 seq
= end_ifcvt_sequence (if_info
);
1032 emit_insn_before_setloc (seq
, if_info
->jump
,
1033 INSN_LOCATOR (if_info
->insn_a
));
1043 /* Convert "if (test) x = 0;" to "x &= -(test == 0);" */
1046 noce_try_store_flag_mask (struct noce_if_info
*if_info
)
1052 if (! no_new_pseudos
1053 && (BRANCH_COST
>= 2
1054 || STORE_FLAG_VALUE
== -1)
1055 && ((if_info
->a
== const0_rtx
1056 && rtx_equal_p (if_info
->b
, if_info
->x
))
1057 || ((reversep
= (reversed_comparison_code (if_info
->cond
,
1060 && if_info
->b
== const0_rtx
1061 && rtx_equal_p (if_info
->a
, if_info
->x
))))
1064 target
= noce_emit_store_flag (if_info
,
1065 gen_reg_rtx (GET_MODE (if_info
->x
)),
1068 target
= expand_simple_binop (GET_MODE (if_info
->x
), AND
,
1070 target
, if_info
->x
, 0,
1075 if (target
!= if_info
->x
)
1076 noce_emit_move_insn (if_info
->x
, target
);
1078 seq
= end_ifcvt_sequence (if_info
);
1082 emit_insn_before_setloc (seq
, if_info
->jump
,
1083 INSN_LOCATOR (if_info
->insn_a
));
1093 /* Helper function for noce_try_cmove and noce_try_cmove_arith. */
1096 noce_emit_cmove (struct noce_if_info
*if_info
, rtx x
, enum rtx_code code
,
1097 rtx cmp_a
, rtx cmp_b
, rtx vfalse
, rtx vtrue
)
1099 /* If earliest == jump, try to build the cmove insn directly.
1100 This is helpful when combine has created some complex condition
1101 (like for alpha's cmovlbs) that we can't hope to regenerate
1102 through the normal interface. */
1104 if (if_info
->cond_earliest
== if_info
->jump
)
1108 tmp
= gen_rtx_fmt_ee (code
, GET_MODE (if_info
->cond
), cmp_a
, cmp_b
);
1109 tmp
= gen_rtx_IF_THEN_ELSE (GET_MODE (x
), tmp
, vtrue
, vfalse
);
1110 tmp
= gen_rtx_SET (VOIDmode
, x
, tmp
);
1113 tmp
= emit_insn (tmp
);
1115 if (recog_memoized (tmp
) >= 0)
1127 /* Don't even try if the comparison operands are weird. */
1128 if (! general_operand (cmp_a
, GET_MODE (cmp_a
))
1129 || ! general_operand (cmp_b
, GET_MODE (cmp_b
)))
1132 #if HAVE_conditional_move
1133 return emit_conditional_move (x
, code
, cmp_a
, cmp_b
, VOIDmode
,
1134 vtrue
, vfalse
, GET_MODE (x
),
1135 (code
== LTU
|| code
== GEU
1136 || code
== LEU
|| code
== GTU
));
1138 /* We'll never get here, as noce_process_if_block doesn't call the
1139 functions involved. Ifdef code, however, should be discouraged
1140 because it leads to typos in the code not selected. However,
1141 emit_conditional_move won't exist either. */
1146 /* Try only simple constants and registers here. More complex cases
1147 are handled in noce_try_cmove_arith after noce_try_store_flag_arith
1148 has had a go at it. */
1151 noce_try_cmove (struct noce_if_info
*if_info
)
1156 if ((CONSTANT_P (if_info
->a
) || register_operand (if_info
->a
, VOIDmode
))
1157 && (CONSTANT_P (if_info
->b
) || register_operand (if_info
->b
, VOIDmode
)))
1161 code
= GET_CODE (if_info
->cond
);
1162 target
= noce_emit_cmove (if_info
, if_info
->x
, code
,
1163 XEXP (if_info
->cond
, 0),
1164 XEXP (if_info
->cond
, 1),
1165 if_info
->a
, if_info
->b
);
1169 if (target
!= if_info
->x
)
1170 noce_emit_move_insn (if_info
->x
, target
);
1172 seq
= end_ifcvt_sequence (if_info
);
1176 emit_insn_before_setloc (seq
, if_info
->jump
,
1177 INSN_LOCATOR (if_info
->insn_a
));
1190 /* Try more complex cases involving conditional_move. */
1193 noce_try_cmove_arith (struct noce_if_info
*if_info
)
1205 /* A conditional move from two memory sources is equivalent to a
1206 conditional on their addresses followed by a load. Don't do this
1207 early because it'll screw alias analysis. Note that we've
1208 already checked for no side effects. */
1209 if (! no_new_pseudos
&& cse_not_expected
1210 && MEM_P (a
) && MEM_P (b
)
1211 && BRANCH_COST
>= 5)
1215 x
= gen_reg_rtx (Pmode
);
1219 /* ??? We could handle this if we knew that a load from A or B could
1220 not fault. This is also true if we've already loaded
1221 from the address along the path from ENTRY. */
1222 else if (may_trap_p (a
) || may_trap_p (b
))
1225 /* if (test) x = a + b; else x = c - d;
1232 code
= GET_CODE (if_info
->cond
);
1233 insn_a
= if_info
->insn_a
;
1234 insn_b
= if_info
->insn_b
;
1236 /* Total insn_rtx_cost should be smaller than branch cost. Exit
1237 if insn_rtx_cost can't be estimated. */
1240 insn_cost
= insn_rtx_cost (PATTERN (insn_a
));
1241 if (insn_cost
== 0 || insn_cost
> COSTS_N_INSNS (BRANCH_COST
))
1250 insn_cost
+= insn_rtx_cost (PATTERN (insn_b
));
1251 if (insn_cost
== 0 || insn_cost
> COSTS_N_INSNS (BRANCH_COST
))
1255 /* Possibly rearrange operands to make things come out more natural. */
1256 if (reversed_comparison_code (if_info
->cond
, if_info
->jump
) != UNKNOWN
)
1259 if (rtx_equal_p (b
, x
))
1261 else if (general_operand (b
, GET_MODE (b
)))
1266 code
= reversed_comparison_code (if_info
->cond
, if_info
->jump
);
1267 tmp
= a
, a
= b
, b
= tmp
;
1268 tmp
= insn_a
, insn_a
= insn_b
, insn_b
= tmp
;
1277 /* If either operand is complex, load it into a register first.
1278 The best way to do this is to copy the original insn. In this
1279 way we preserve any clobbers etc that the insn may have had.
1280 This is of course not possible in the IS_MEM case. */
1281 if (! general_operand (a
, GET_MODE (a
)))
1286 goto end_seq_and_fail
;
1290 tmp
= gen_reg_rtx (GET_MODE (a
));
1291 tmp
= emit_insn (gen_rtx_SET (VOIDmode
, tmp
, a
));
1294 goto end_seq_and_fail
;
1297 a
= gen_reg_rtx (GET_MODE (a
));
1298 tmp
= copy_rtx (insn_a
);
1299 set
= single_set (tmp
);
1301 tmp
= emit_insn (PATTERN (tmp
));
1303 if (recog_memoized (tmp
) < 0)
1304 goto end_seq_and_fail
;
1306 if (! general_operand (b
, GET_MODE (b
)))
1311 goto end_seq_and_fail
;
1315 tmp
= gen_reg_rtx (GET_MODE (b
));
1316 tmp
= gen_rtx_SET (VOIDmode
, tmp
, b
);
1319 goto end_seq_and_fail
;
1322 b
= gen_reg_rtx (GET_MODE (b
));
1323 tmp
= copy_rtx (insn_b
);
1324 set
= single_set (tmp
);
1326 tmp
= PATTERN (tmp
);
1329 /* If insn to set up A clobbers any registers B depends on, try to
1330 swap insn that sets up A with the one that sets up B. If even
1331 that doesn't help, punt. */
1332 last
= get_last_insn ();
1333 if (last
&& modified_in_p (orig_b
, last
))
1335 tmp
= emit_insn_before (tmp
, get_insns ());
1336 if (modified_in_p (orig_a
, tmp
))
1337 goto end_seq_and_fail
;
1340 tmp
= emit_insn (tmp
);
1342 if (recog_memoized (tmp
) < 0)
1343 goto end_seq_and_fail
;
1346 target
= noce_emit_cmove (if_info
, x
, code
, XEXP (if_info
->cond
, 0),
1347 XEXP (if_info
->cond
, 1), a
, b
);
1350 goto end_seq_and_fail
;
1352 /* If we're handling a memory for above, emit the load now. */
1355 tmp
= gen_rtx_MEM (GET_MODE (if_info
->x
), target
);
1357 /* Copy over flags as appropriate. */
1358 if (MEM_VOLATILE_P (if_info
->a
) || MEM_VOLATILE_P (if_info
->b
))
1359 MEM_VOLATILE_P (tmp
) = 1;
1360 if (MEM_IN_STRUCT_P (if_info
->a
) && MEM_IN_STRUCT_P (if_info
->b
))
1361 MEM_IN_STRUCT_P (tmp
) = 1;
1362 if (MEM_SCALAR_P (if_info
->a
) && MEM_SCALAR_P (if_info
->b
))
1363 MEM_SCALAR_P (tmp
) = 1;
1364 if (MEM_ALIAS_SET (if_info
->a
) == MEM_ALIAS_SET (if_info
->b
))
1365 set_mem_alias_set (tmp
, MEM_ALIAS_SET (if_info
->a
));
1367 MIN (MEM_ALIGN (if_info
->a
), MEM_ALIGN (if_info
->b
)));
1369 noce_emit_move_insn (if_info
->x
, tmp
);
1371 else if (target
!= x
)
1372 noce_emit_move_insn (x
, target
);
1374 tmp
= end_ifcvt_sequence (if_info
);
1378 emit_insn_before_setloc (tmp
, if_info
->jump
, INSN_LOCATOR (if_info
->insn_a
));
1386 /* For most cases, the simplified condition we found is the best
1387 choice, but this is not the case for the min/max/abs transforms.
1388 For these we wish to know that it is A or B in the condition. */
1391 noce_get_alt_condition (struct noce_if_info
*if_info
, rtx target
,
1394 rtx cond
, set
, insn
;
1397 /* If target is already mentioned in the known condition, return it. */
1398 if (reg_mentioned_p (target
, if_info
->cond
))
1400 *earliest
= if_info
->cond_earliest
;
1401 return if_info
->cond
;
1404 set
= pc_set (if_info
->jump
);
1405 cond
= XEXP (SET_SRC (set
), 0);
1407 = GET_CODE (XEXP (SET_SRC (set
), 2)) == LABEL_REF
1408 && XEXP (XEXP (SET_SRC (set
), 2), 0) == JUMP_LABEL (if_info
->jump
);
1410 /* If we're looking for a constant, try to make the conditional
1411 have that constant in it. There are two reasons why it may
1412 not have the constant we want:
1414 1. GCC may have needed to put the constant in a register, because
1415 the target can't compare directly against that constant. For
1416 this case, we look for a SET immediately before the comparison
1417 that puts a constant in that register.
1419 2. GCC may have canonicalized the conditional, for example
1420 replacing "if x < 4" with "if x <= 3". We can undo that (or
1421 make equivalent types of changes) to get the constants we need
1422 if they're off by one in the right direction. */
1424 if (GET_CODE (target
) == CONST_INT
)
1426 enum rtx_code code
= GET_CODE (if_info
->cond
);
1427 rtx op_a
= XEXP (if_info
->cond
, 0);
1428 rtx op_b
= XEXP (if_info
->cond
, 1);
1431 /* First, look to see if we put a constant in a register. */
1432 prev_insn
= PREV_INSN (if_info
->cond_earliest
);
1434 && INSN_P (prev_insn
)
1435 && GET_CODE (PATTERN (prev_insn
)) == SET
)
1437 rtx src
= find_reg_equal_equiv_note (prev_insn
);
1439 src
= SET_SRC (PATTERN (prev_insn
));
1440 if (GET_CODE (src
) == CONST_INT
)
1442 if (rtx_equal_p (op_a
, SET_DEST (PATTERN (prev_insn
))))
1444 else if (rtx_equal_p (op_b
, SET_DEST (PATTERN (prev_insn
))))
1447 if (GET_CODE (op_a
) == CONST_INT
)
1452 code
= swap_condition (code
);
1457 /* Now, look to see if we can get the right constant by
1458 adjusting the conditional. */
1459 if (GET_CODE (op_b
) == CONST_INT
)
1461 HOST_WIDE_INT desired_val
= INTVAL (target
);
1462 HOST_WIDE_INT actual_val
= INTVAL (op_b
);
1467 if (actual_val
== desired_val
+ 1)
1470 op_b
= GEN_INT (desired_val
);
1474 if (actual_val
== desired_val
- 1)
1477 op_b
= GEN_INT (desired_val
);
1481 if (actual_val
== desired_val
- 1)
1484 op_b
= GEN_INT (desired_val
);
1488 if (actual_val
== desired_val
+ 1)
1491 op_b
= GEN_INT (desired_val
);
1499 /* If we made any changes, generate a new conditional that is
1500 equivalent to what we started with, but has the right
1502 if (code
!= GET_CODE (if_info
->cond
)
1503 || op_a
!= XEXP (if_info
->cond
, 0)
1504 || op_b
!= XEXP (if_info
->cond
, 1))
1506 cond
= gen_rtx_fmt_ee (code
, GET_MODE (cond
), op_a
, op_b
);
1507 *earliest
= if_info
->cond_earliest
;
1512 cond
= canonicalize_condition (if_info
->jump
, cond
, reverse
,
1513 earliest
, target
, false, true);
1514 if (! cond
|| ! reg_mentioned_p (target
, cond
))
1517 /* We almost certainly searched back to a different place.
1518 Need to re-verify correct lifetimes. */
1520 /* X may not be mentioned in the range (cond_earliest, jump]. */
1521 for (insn
= if_info
->jump
; insn
!= *earliest
; insn
= PREV_INSN (insn
))
1522 if (INSN_P (insn
) && reg_overlap_mentioned_p (if_info
->x
, PATTERN (insn
)))
1525 /* A and B may not be modified in the range [cond_earliest, jump). */
1526 for (insn
= *earliest
; insn
!= if_info
->jump
; insn
= NEXT_INSN (insn
))
1528 && (modified_in_p (if_info
->a
, insn
)
1529 || modified_in_p (if_info
->b
, insn
)))
1535 /* Convert "if (a < b) x = a; else x = b;" to "x = min(a, b);", etc. */
1538 noce_try_minmax (struct noce_if_info
*if_info
)
1540 rtx cond
, earliest
, target
, seq
;
1541 enum rtx_code code
, op
;
1544 /* ??? Can't guarantee that expand_binop won't create pseudos. */
1548 /* ??? Reject modes with NaNs or signed zeros since we don't know how
1549 they will be resolved with an SMIN/SMAX. It wouldn't be too hard
1550 to get the target to tell us... */
1551 if (HONOR_SIGNED_ZEROS (GET_MODE (if_info
->x
))
1552 || HONOR_NANS (GET_MODE (if_info
->x
)))
1555 cond
= noce_get_alt_condition (if_info
, if_info
->a
, &earliest
);
1559 /* Verify the condition is of the form we expect, and canonicalize
1560 the comparison code. */
1561 code
= GET_CODE (cond
);
1562 if (rtx_equal_p (XEXP (cond
, 0), if_info
->a
))
1564 if (! rtx_equal_p (XEXP (cond
, 1), if_info
->b
))
1567 else if (rtx_equal_p (XEXP (cond
, 1), if_info
->a
))
1569 if (! rtx_equal_p (XEXP (cond
, 0), if_info
->b
))
1571 code
= swap_condition (code
);
1576 /* Determine what sort of operation this is. Note that the code is for
1577 a taken branch, so the code->operation mapping appears backwards. */
1610 target
= expand_simple_binop (GET_MODE (if_info
->x
), op
,
1611 if_info
->a
, if_info
->b
,
1612 if_info
->x
, unsignedp
, OPTAB_WIDEN
);
1618 if (target
!= if_info
->x
)
1619 noce_emit_move_insn (if_info
->x
, target
);
1621 seq
= end_ifcvt_sequence (if_info
);
1625 emit_insn_before_setloc (seq
, if_info
->jump
, INSN_LOCATOR (if_info
->insn_a
));
1626 if_info
->cond
= cond
;
1627 if_info
->cond_earliest
= earliest
;
1632 /* Convert "if (a < 0) x = -a; else x = a;" to "x = abs(a);", etc. */
1635 noce_try_abs (struct noce_if_info
*if_info
)
1637 rtx cond
, earliest
, target
, seq
, a
, b
, c
;
1640 /* ??? Can't guarantee that expand_binop won't create pseudos. */
1644 /* Recognize A and B as constituting an ABS or NABS. */
1647 if (GET_CODE (a
) == NEG
&& rtx_equal_p (XEXP (a
, 0), b
))
1649 else if (GET_CODE (b
) == NEG
&& rtx_equal_p (XEXP (b
, 0), a
))
1651 c
= a
; a
= b
; b
= c
;
1657 cond
= noce_get_alt_condition (if_info
, b
, &earliest
);
1661 /* Verify the condition is of the form we expect. */
1662 if (rtx_equal_p (XEXP (cond
, 0), b
))
1664 else if (rtx_equal_p (XEXP (cond
, 1), b
))
1669 /* Verify that C is zero. Search backward through the block for
1670 a REG_EQUAL note if necessary. */
1673 rtx insn
, note
= NULL
;
1674 for (insn
= earliest
;
1675 insn
!= BB_HEAD (if_info
->test_bb
);
1676 insn
= PREV_INSN (insn
))
1678 && ((note
= find_reg_note (insn
, REG_EQUAL
, c
))
1679 || (note
= find_reg_note (insn
, REG_EQUIV
, c
))))
1686 && GET_CODE (XEXP (c
, 0)) == SYMBOL_REF
1687 && CONSTANT_POOL_ADDRESS_P (XEXP (c
, 0)))
1688 c
= get_pool_constant (XEXP (c
, 0));
1690 /* Work around funny ideas get_condition has wrt canonicalization.
1691 Note that these rtx constants are known to be CONST_INT, and
1692 therefore imply integer comparisons. */
1693 if (c
== constm1_rtx
&& GET_CODE (cond
) == GT
)
1695 else if (c
== const1_rtx
&& GET_CODE (cond
) == LT
)
1697 else if (c
!= CONST0_RTX (GET_MODE (b
)))
1700 /* Determine what sort of operation this is. */
1701 switch (GET_CODE (cond
))
1720 target
= expand_abs_nojump (GET_MODE (if_info
->x
), b
, if_info
->x
, 1);
1722 /* ??? It's a quandary whether cmove would be better here, especially
1723 for integers. Perhaps combine will clean things up. */
1724 if (target
&& negate
)
1725 target
= expand_simple_unop (GET_MODE (target
), NEG
, target
, if_info
->x
, 0);
1733 if (target
!= if_info
->x
)
1734 noce_emit_move_insn (if_info
->x
, target
);
1736 seq
= end_ifcvt_sequence (if_info
);
1740 emit_insn_before_setloc (seq
, if_info
->jump
, INSN_LOCATOR (if_info
->insn_a
));
1741 if_info
->cond
= cond
;
1742 if_info
->cond_earliest
= earliest
;
1747 /* Convert "if (m < 0) x = b; else x = 0;" to "x = (m >> C) & b;". */
1750 noce_try_sign_mask (struct noce_if_info
*if_info
)
1752 rtx cond
, t
, m
, c
, seq
;
1753 enum machine_mode mode
;
1759 cond
= if_info
->cond
;
1760 code
= GET_CODE (cond
);
1765 if (if_info
->a
== const0_rtx
)
1767 if ((code
== LT
&& c
== const0_rtx
)
1768 || (code
== LE
&& c
== constm1_rtx
))
1771 else if (if_info
->b
== const0_rtx
)
1773 if ((code
== GE
&& c
== const0_rtx
)
1774 || (code
== GT
&& c
== constm1_rtx
))
1778 if (! t
|| side_effects_p (t
))
1781 /* We currently don't handle different modes. */
1782 mode
= GET_MODE (t
);
1783 if (GET_MODE (m
) != mode
)
1786 /* This is only profitable if T is cheap, or T is unconditionally
1787 executed/evaluated in the original insn sequence. */
1788 if (rtx_cost (t
, SET
) >= COSTS_N_INSNS (2)
1789 && (!if_info
->b_unconditional
1790 || t
!= if_info
->b
))
1794 /* Use emit_store_flag to generate "m < 0 ? -1 : 0" instead of expanding
1795 "(signed) m >> 31" directly. This benefits targets with specialized
1796 insns to obtain the signmask, but still uses ashr_optab otherwise. */
1797 m
= emit_store_flag (gen_reg_rtx (mode
), LT
, m
, const0_rtx
, mode
, 0, -1);
1798 t
= m
? expand_binop (mode
, and_optab
, m
, t
, NULL_RTX
, 0, OPTAB_DIRECT
)
1807 noce_emit_move_insn (if_info
->x
, t
);
1809 seq
= end_ifcvt_sequence (if_info
);
1813 emit_insn_before_setloc (seq
, if_info
->jump
, INSN_LOCATOR (if_info
->insn_a
));
1818 /* Similar to get_condition, only the resulting condition must be
1819 valid at JUMP, instead of at EARLIEST. */
1822 noce_get_condition (rtx jump
, rtx
*earliest
)
1827 if (! any_condjump_p (jump
))
1830 set
= pc_set (jump
);
1832 /* If this branches to JUMP_LABEL when the condition is false,
1833 reverse the condition. */
1834 reverse
= (GET_CODE (XEXP (SET_SRC (set
), 2)) == LABEL_REF
1835 && XEXP (XEXP (SET_SRC (set
), 2), 0) == JUMP_LABEL (jump
));
1837 /* If the condition variable is a register and is MODE_INT, accept it. */
1839 cond
= XEXP (SET_SRC (set
), 0);
1840 tmp
= XEXP (cond
, 0);
1841 if (REG_P (tmp
) && GET_MODE_CLASS (GET_MODE (tmp
)) == MODE_INT
)
1846 cond
= gen_rtx_fmt_ee (reverse_condition (GET_CODE (cond
)),
1847 GET_MODE (cond
), tmp
, XEXP (cond
, 1));
1851 /* Otherwise, fall back on canonicalize_condition to do the dirty
1852 work of manipulating MODE_CC values and COMPARE rtx codes. */
1853 return canonicalize_condition (jump
, cond
, reverse
, earliest
,
1854 NULL_RTX
, false, true);
1857 /* Return true if OP is ok for if-then-else processing. */
1860 noce_operand_ok (rtx op
)
1862 /* We special-case memories, so handle any of them with
1863 no address side effects. */
1865 return ! side_effects_p (XEXP (op
, 0));
1867 if (side_effects_p (op
))
1870 return ! may_trap_p (op
);
1873 /* Given a simple IF-THEN or IF-THEN-ELSE block, attempt to convert it
1874 without using conditional execution. Return TRUE if we were
1875 successful at converting the block. */
1878 noce_process_if_block (struct ce_if_block
* ce_info
)
1880 basic_block test_bb
= ce_info
->test_bb
; /* test block */
1881 basic_block then_bb
= ce_info
->then_bb
; /* THEN */
1882 basic_block else_bb
= ce_info
->else_bb
; /* ELSE or NULL */
1883 struct noce_if_info if_info
;
1886 rtx orig_x
, x
, a
, b
;
1889 /* We're looking for patterns of the form
1891 (1) if (...) x = a; else x = b;
1892 (2) x = b; if (...) x = a;
1893 (3) if (...) x = a; // as if with an initial x = x.
1895 The later patterns require jumps to be more expensive.
1897 ??? For future expansion, look for multiple X in such patterns. */
1899 /* If test is comprised of && or || elements, don't handle it unless it is
1900 the special case of && elements without an ELSE block. */
1901 if (ce_info
->num_multiple_test_blocks
)
1903 if (else_bb
|| ! ce_info
->and_and_p
)
1906 ce_info
->test_bb
= test_bb
= ce_info
->last_test_bb
;
1907 ce_info
->num_multiple_test_blocks
= 0;
1908 ce_info
->num_and_and_blocks
= 0;
1909 ce_info
->num_or_or_blocks
= 0;
1912 /* If this is not a standard conditional jump, we can't parse it. */
1913 jump
= BB_END (test_bb
);
1914 cond
= noce_get_condition (jump
, &if_info
.cond_earliest
);
1918 /* If the conditional jump is more than just a conditional
1919 jump, then we can not do if-conversion on this block. */
1920 if (! onlyjump_p (jump
))
1923 /* We must be comparing objects whose modes imply the size. */
1924 if (GET_MODE (XEXP (cond
, 0)) == BLKmode
)
1927 /* Look for one of the potential sets. */
1928 insn_a
= first_active_insn (then_bb
);
1930 || insn_a
!= last_active_insn (then_bb
, FALSE
)
1931 || (set_a
= single_set (insn_a
)) == NULL_RTX
)
1934 x
= SET_DEST (set_a
);
1935 a
= SET_SRC (set_a
);
1937 /* Look for the other potential set. Make sure we've got equivalent
1939 /* ??? This is overconservative. Storing to two different mems is
1940 as easy as conditionally computing the address. Storing to a
1941 single mem merely requires a scratch memory to use as one of the
1942 destination addresses; often the memory immediately below the
1943 stack pointer is available for this. */
1947 insn_b
= first_active_insn (else_bb
);
1949 || insn_b
!= last_active_insn (else_bb
, FALSE
)
1950 || (set_b
= single_set (insn_b
)) == NULL_RTX
1951 || ! rtx_equal_p (x
, SET_DEST (set_b
)))
1956 insn_b
= prev_nonnote_insn (if_info
.cond_earliest
);
1957 /* We're going to be moving the evaluation of B down from above
1958 COND_EARLIEST to JUMP. Make sure the relevant data is still
1961 || !NONJUMP_INSN_P (insn_b
)
1962 || (set_b
= single_set (insn_b
)) == NULL_RTX
1963 || ! rtx_equal_p (x
, SET_DEST (set_b
))
1964 || reg_overlap_mentioned_p (x
, SET_SRC (set_b
))
1965 || modified_between_p (SET_SRC (set_b
),
1966 PREV_INSN (if_info
.cond_earliest
), jump
)
1967 /* Likewise with X. In particular this can happen when
1968 noce_get_condition looks farther back in the instruction
1969 stream than one might expect. */
1970 || reg_overlap_mentioned_p (x
, cond
)
1971 || reg_overlap_mentioned_p (x
, a
)
1972 || modified_between_p (x
, PREV_INSN (if_info
.cond_earliest
), jump
))
1973 insn_b
= set_b
= NULL_RTX
;
1976 /* If x has side effects then only the if-then-else form is safe to
1977 convert. But even in that case we would need to restore any notes
1978 (such as REG_INC) at then end. That can be tricky if
1979 noce_emit_move_insn expands to more than one insn, so disable the
1980 optimization entirely for now if there are side effects. */
1981 if (side_effects_p (x
))
1984 /* If x is a read-only memory, then the program is valid only if we
1985 avoid the store into it. If there are stores on both the THEN and
1986 ELSE arms, then we can go ahead with the conversion; either the
1987 program is broken, or the condition is always false such that the
1988 other memory is selected. */
1989 if (!set_b
&& MEM_P (x
) && MEM_READONLY_P (x
))
1992 b
= (set_b
? SET_SRC (set_b
) : x
);
1994 /* Only operate on register destinations, and even then avoid extending
1995 the lifetime of hard registers on small register class machines. */
1998 || (SMALL_REGISTER_CLASSES
1999 && REGNO (x
) < FIRST_PSEUDO_REGISTER
))
2001 if (no_new_pseudos
|| GET_MODE (x
) == BLKmode
)
2003 x
= gen_reg_rtx (GET_MODE (GET_CODE (x
) == STRICT_LOW_PART
2004 ? XEXP (x
, 0) : x
));
2007 /* Don't operate on sources that may trap or are volatile. */
2008 if (! noce_operand_ok (a
) || ! noce_operand_ok (b
))
2011 /* Set up the info block for our subroutines. */
2012 if_info
.test_bb
= test_bb
;
2013 if_info
.cond
= cond
;
2014 if_info
.jump
= jump
;
2015 if_info
.insn_a
= insn_a
;
2016 if_info
.insn_b
= insn_b
;
2020 if_info
.b_unconditional
= else_bb
== 0;
2022 /* Try optimizations in some approximation of a useful order. */
2023 /* ??? Should first look to see if X is live incoming at all. If it
2024 isn't, we don't need anything but an unconditional set. */
2026 /* Look and see if A and B are really the same. Avoid creating silly
2027 cmove constructs that no one will fix up later. */
2028 if (rtx_equal_p (a
, b
))
2030 /* If we have an INSN_B, we don't have to create any new rtl. Just
2031 move the instruction that we already have. If we don't have an
2032 INSN_B, that means that A == X, and we've got a noop move. In
2033 that case don't do anything and let the code below delete INSN_A. */
2034 if (insn_b
&& else_bb
)
2038 if (else_bb
&& insn_b
== BB_END (else_bb
))
2039 BB_END (else_bb
) = PREV_INSN (insn_b
);
2040 reorder_insns (insn_b
, insn_b
, PREV_INSN (jump
));
2042 /* If there was a REG_EQUAL note, delete it since it may have been
2043 true due to this insn being after a jump. */
2044 if ((note
= find_reg_note (insn_b
, REG_EQUAL
, NULL_RTX
)) != 0)
2045 remove_note (insn_b
, note
);
2049 /* If we have "x = b; if (...) x = a;", and x has side-effects, then
2050 x must be executed twice. */
2051 else if (insn_b
&& side_effects_p (orig_x
))
2058 /* Disallow the "if (...) x = a;" form (with an implicit "else x = x;")
2059 for most optimizations if writing to x may trap, i.e. it's a memory
2060 other than a static var or a stack slot. */
2063 && ! MEM_NOTRAP_P (orig_x
)
2064 && rtx_addr_can_trap_p (XEXP (orig_x
, 0)))
2066 if (HAVE_conditional_move
)
2068 if (noce_try_cmove (&if_info
))
2070 if (! HAVE_conditional_execution
2071 && noce_try_cmove_arith (&if_info
))
2077 if (noce_try_move (&if_info
))
2079 if (noce_try_store_flag (&if_info
))
2081 if (noce_try_minmax (&if_info
))
2083 if (noce_try_abs (&if_info
))
2085 if (HAVE_conditional_move
2086 && noce_try_cmove (&if_info
))
2088 if (! HAVE_conditional_execution
)
2090 if (noce_try_store_flag_constants (&if_info
))
2092 if (noce_try_addcc (&if_info
))
2094 if (noce_try_store_flag_mask (&if_info
))
2096 if (HAVE_conditional_move
2097 && noce_try_cmove_arith (&if_info
))
2099 if (noce_try_sign_mask (&if_info
))
2106 /* The original sets may now be killed. */
2107 delete_insn (insn_a
);
2109 /* Several special cases here: First, we may have reused insn_b above,
2110 in which case insn_b is now NULL. Second, we want to delete insn_b
2111 if it came from the ELSE block, because follows the now correct
2112 write that appears in the TEST block. However, if we got insn_b from
2113 the TEST block, it may in fact be loading data needed for the comparison.
2114 We'll let life_analysis remove the insn if it's really dead. */
2115 if (insn_b
&& else_bb
)
2116 delete_insn (insn_b
);
2118 /* The new insns will have been inserted immediately before the jump. We
2119 should be able to remove the jump with impunity, but the condition itself
2120 may have been modified by gcse to be shared across basic blocks. */
2123 /* If we used a temporary, fix it up now. */
2127 noce_emit_move_insn (orig_x
, x
);
2128 insn_b
= get_insns ();
2129 set_used_flags (orig_x
);
2130 unshare_all_rtl_in_chain (insn_b
);
2133 emit_insn_after_setloc (insn_b
, BB_END (test_bb
), INSN_LOCATOR (insn_a
));
2136 /* Merge the blocks! */
2137 merge_if_block (ce_info
);
2142 /* Attempt to convert an IF-THEN or IF-THEN-ELSE block into
2143 straight line code. Return true if successful. */
2146 process_if_block (struct ce_if_block
* ce_info
)
2148 if (! reload_completed
2149 && noce_process_if_block (ce_info
))
2152 if (HAVE_conditional_execution
&& reload_completed
)
2154 /* If we have && and || tests, try to first handle combining the && and
2155 || tests into the conditional code, and if that fails, go back and
2156 handle it without the && and ||, which at present handles the && case
2157 if there was no ELSE block. */
2158 if (cond_exec_process_if_block (ce_info
, TRUE
))
2161 if (ce_info
->num_multiple_test_blocks
)
2165 if (cond_exec_process_if_block (ce_info
, FALSE
))
2173 /* Merge the blocks and mark for local life update. */
2176 merge_if_block (struct ce_if_block
* ce_info
)
2178 basic_block test_bb
= ce_info
->test_bb
; /* last test block */
2179 basic_block then_bb
= ce_info
->then_bb
; /* THEN */
2180 basic_block else_bb
= ce_info
->else_bb
; /* ELSE or NULL */
2181 basic_block join_bb
= ce_info
->join_bb
; /* join block */
2182 basic_block combo_bb
;
2184 /* All block merging is done into the lower block numbers. */
2188 /* Merge any basic blocks to handle && and || subtests. Each of
2189 the blocks are on the fallthru path from the predecessor block. */
2190 if (ce_info
->num_multiple_test_blocks
> 0)
2192 basic_block bb
= test_bb
;
2193 basic_block last_test_bb
= ce_info
->last_test_bb
;
2194 basic_block fallthru
= block_fallthru (bb
);
2199 fallthru
= block_fallthru (bb
);
2200 merge_blocks (combo_bb
, bb
);
2203 while (bb
!= last_test_bb
);
2206 /* Merge TEST block into THEN block. Normally the THEN block won't have a
2207 label, but it might if there were || tests. That label's count should be
2208 zero, and it normally should be removed. */
2212 if (combo_bb
->global_live_at_end
)
2213 COPY_REG_SET (combo_bb
->global_live_at_end
,
2214 then_bb
->global_live_at_end
);
2215 merge_blocks (combo_bb
, then_bb
);
2219 /* The ELSE block, if it existed, had a label. That label count
2220 will almost always be zero, but odd things can happen when labels
2221 get their addresses taken. */
2224 merge_blocks (combo_bb
, else_bb
);
2228 /* If there was no join block reported, that means it was not adjacent
2229 to the others, and so we cannot merge them. */
2233 rtx last
= BB_END (combo_bb
);
2235 /* The outgoing edge for the current COMBO block should already
2236 be correct. Verify this. */
2237 if (EDGE_COUNT (combo_bb
->succs
) == 0)
2238 gcc_assert (find_reg_note (last
, REG_NORETURN
, NULL
)
2239 || (NONJUMP_INSN_P (last
)
2240 && GET_CODE (PATTERN (last
)) == TRAP_IF
2241 && (TRAP_CONDITION (PATTERN (last
))
2242 == const_true_rtx
)));
2245 /* There should still be something at the end of the THEN or ELSE
2246 blocks taking us to our final destination. */
2247 gcc_assert (JUMP_P (last
)
2248 || (EDGE_SUCC (combo_bb
, 0)->dest
== EXIT_BLOCK_PTR
2250 && SIBLING_CALL_P (last
))
2251 || ((EDGE_SUCC (combo_bb
, 0)->flags
& EDGE_EH
)
2252 && can_throw_internal (last
)));
2255 /* The JOIN block may have had quite a number of other predecessors too.
2256 Since we've already merged the TEST, THEN and ELSE blocks, we should
2257 have only one remaining edge from our if-then-else diamond. If there
2258 is more than one remaining edge, it must come from elsewhere. There
2259 may be zero incoming edges if the THEN block didn't actually join
2260 back up (as with a call to a non-return function). */
2261 else if (EDGE_COUNT (join_bb
->preds
) < 2
2262 && join_bb
!= EXIT_BLOCK_PTR
)
2264 /* We can merge the JOIN. */
2265 if (combo_bb
->global_live_at_end
)
2266 COPY_REG_SET (combo_bb
->global_live_at_end
,
2267 join_bb
->global_live_at_end
);
2269 merge_blocks (combo_bb
, join_bb
);
2274 /* We cannot merge the JOIN. */
2276 /* The outgoing edge for the current COMBO block should already
2277 be correct. Verify this. */
2278 gcc_assert (single_succ_p (combo_bb
)
2279 && single_succ (combo_bb
) == join_bb
);
2281 /* Remove the jump and cruft from the end of the COMBO block. */
2282 if (join_bb
!= EXIT_BLOCK_PTR
)
2283 tidy_fallthru_edge (single_succ_edge (combo_bb
));
2286 num_updated_if_blocks
++;
2289 /* Find a block ending in a simple IF condition and try to transform it
2290 in some way. When converting a multi-block condition, put the new code
2291 in the first such block and delete the rest. Return a pointer to this
2292 first block if some transformation was done. Return NULL otherwise. */
2295 find_if_header (basic_block test_bb
, int pass
)
2297 ce_if_block_t ce_info
;
2301 /* The kind of block we're looking for has exactly two successors. */
2302 if (EDGE_COUNT (test_bb
->succs
) != 2)
2305 then_edge
= EDGE_SUCC (test_bb
, 0);
2306 else_edge
= EDGE_SUCC (test_bb
, 1);
2308 /* Neither edge should be abnormal. */
2309 if ((then_edge
->flags
& EDGE_COMPLEX
)
2310 || (else_edge
->flags
& EDGE_COMPLEX
))
2313 /* Nor exit the loop. */
2314 if ((then_edge
->flags
& EDGE_LOOP_EXIT
)
2315 || (else_edge
->flags
& EDGE_LOOP_EXIT
))
2318 /* The THEN edge is canonically the one that falls through. */
2319 if (then_edge
->flags
& EDGE_FALLTHRU
)
2321 else if (else_edge
->flags
& EDGE_FALLTHRU
)
2324 else_edge
= then_edge
;
2328 /* Otherwise this must be a multiway branch of some sort. */
2331 memset (&ce_info
, '\0', sizeof (ce_info
));
2332 ce_info
.test_bb
= test_bb
;
2333 ce_info
.then_bb
= then_edge
->dest
;
2334 ce_info
.else_bb
= else_edge
->dest
;
2335 ce_info
.pass
= pass
;
2337 #ifdef IFCVT_INIT_EXTRA_FIELDS
2338 IFCVT_INIT_EXTRA_FIELDS (&ce_info
);
2341 if (find_if_block (&ce_info
))
2344 if (HAVE_trap
&& HAVE_conditional_trap
2345 && find_cond_trap (test_bb
, then_edge
, else_edge
))
2348 if (dom_computed
[CDI_POST_DOMINATORS
] >= DOM_NO_FAST_QUERY
2349 && (! HAVE_conditional_execution
|| reload_completed
))
2351 if (find_if_case_1 (test_bb
, then_edge
, else_edge
))
2353 if (find_if_case_2 (test_bb
, then_edge
, else_edge
))
2361 fprintf (dump_file
, "Conversion succeeded on pass %d.\n", pass
);
2362 return ce_info
.test_bb
;
2365 /* Return true if a block has two edges, one of which falls through to the next
2366 block, and the other jumps to a specific block, so that we can tell if the
2367 block is part of an && test or an || test. Returns either -1 or the number
2368 of non-note, non-jump, non-USE/CLOBBER insns in the block. */
2371 block_jumps_and_fallthru_p (basic_block cur_bb
, basic_block target_bb
)
2374 int fallthru_p
= FALSE
;
2381 if (!cur_bb
|| !target_bb
)
2384 /* If no edges, obviously it doesn't jump or fallthru. */
2385 if (EDGE_COUNT (cur_bb
->succs
) == 0)
2388 FOR_EACH_EDGE (cur_edge
, ei
, cur_bb
->succs
)
2390 if (cur_edge
->flags
& EDGE_COMPLEX
)
2391 /* Anything complex isn't what we want. */
2394 else if (cur_edge
->flags
& EDGE_FALLTHRU
)
2397 else if (cur_edge
->dest
== target_bb
)
2404 if ((jump_p
& fallthru_p
) == 0)
2407 /* Don't allow calls in the block, since this is used to group && and ||
2408 together for conditional execution support. ??? we should support
2409 conditional execution support across calls for IA-64 some day, but
2410 for now it makes the code simpler. */
2411 end
= BB_END (cur_bb
);
2412 insn
= BB_HEAD (cur_bb
);
2414 while (insn
!= NULL_RTX
)
2421 && GET_CODE (PATTERN (insn
)) != USE
2422 && GET_CODE (PATTERN (insn
)) != CLOBBER
)
2428 insn
= NEXT_INSN (insn
);
2434 /* Determine if a given basic block heads a simple IF-THEN or IF-THEN-ELSE
2435 block. If so, we'll try to convert the insns to not require the branch.
2436 Return TRUE if we were successful at converting the block. */
2439 find_if_block (struct ce_if_block
* ce_info
)
2441 basic_block test_bb
= ce_info
->test_bb
;
2442 basic_block then_bb
= ce_info
->then_bb
;
2443 basic_block else_bb
= ce_info
->else_bb
;
2444 basic_block join_bb
= NULL_BLOCK
;
2449 ce_info
->last_test_bb
= test_bb
;
2451 /* Discover if any fall through predecessors of the current test basic block
2452 were && tests (which jump to the else block) or || tests (which jump to
2454 if (HAVE_conditional_execution
&& reload_completed
2455 && single_pred_p (test_bb
)
2456 && single_pred_edge (test_bb
)->flags
== EDGE_FALLTHRU
)
2458 basic_block bb
= single_pred (test_bb
);
2459 basic_block target_bb
;
2460 int max_insns
= MAX_CONDITIONAL_EXECUTE
;
2463 /* Determine if the preceding block is an && or || block. */
2464 if ((n_insns
= block_jumps_and_fallthru_p (bb
, else_bb
)) >= 0)
2466 ce_info
->and_and_p
= TRUE
;
2467 target_bb
= else_bb
;
2469 else if ((n_insns
= block_jumps_and_fallthru_p (bb
, then_bb
)) >= 0)
2471 ce_info
->and_and_p
= FALSE
;
2472 target_bb
= then_bb
;
2475 target_bb
= NULL_BLOCK
;
2477 if (target_bb
&& n_insns
<= max_insns
)
2479 int total_insns
= 0;
2482 ce_info
->last_test_bb
= test_bb
;
2484 /* Found at least one && or || block, look for more. */
2487 ce_info
->test_bb
= test_bb
= bb
;
2488 total_insns
+= n_insns
;
2491 if (!single_pred_p (bb
))
2494 bb
= single_pred (bb
);
2495 n_insns
= block_jumps_and_fallthru_p (bb
, target_bb
);
2497 while (n_insns
>= 0 && (total_insns
+ n_insns
) <= max_insns
);
2499 ce_info
->num_multiple_test_blocks
= blocks
;
2500 ce_info
->num_multiple_test_insns
= total_insns
;
2502 if (ce_info
->and_and_p
)
2503 ce_info
->num_and_and_blocks
= blocks
;
2505 ce_info
->num_or_or_blocks
= blocks
;
2509 /* The THEN block of an IF-THEN combo must have exactly one predecessor,
2510 other than any || blocks which jump to the THEN block. */
2511 if ((EDGE_COUNT (then_bb
->preds
) - ce_info
->num_or_or_blocks
) != 1)
2514 /* The edges of the THEN and ELSE blocks cannot have complex edges. */
2515 FOR_EACH_EDGE (cur_edge
, ei
, then_bb
->preds
)
2517 if (cur_edge
->flags
& EDGE_COMPLEX
)
2521 FOR_EACH_EDGE (cur_edge
, ei
, else_bb
->preds
)
2523 if (cur_edge
->flags
& EDGE_COMPLEX
)
2527 /* The THEN block of an IF-THEN combo must have zero or one successors. */
2528 if (EDGE_COUNT (then_bb
->succs
) > 0
2529 && (!single_succ_p (then_bb
)
2530 || (single_succ_edge (then_bb
)->flags
& EDGE_COMPLEX
)
2531 || (flow2_completed
&& tablejump_p (BB_END (then_bb
), NULL
, NULL
))))
2534 /* If the THEN block has no successors, conditional execution can still
2535 make a conditional call. Don't do this unless the ELSE block has
2536 only one incoming edge -- the CFG manipulation is too ugly otherwise.
2537 Check for the last insn of the THEN block being an indirect jump, which
2538 is listed as not having any successors, but confuses the rest of the CE
2539 code processing. ??? we should fix this in the future. */
2540 if (EDGE_COUNT (then_bb
->succs
) == 0)
2542 if (single_pred_p (else_bb
))
2544 rtx last_insn
= BB_END (then_bb
);
2547 && NOTE_P (last_insn
)
2548 && last_insn
!= BB_HEAD (then_bb
))
2549 last_insn
= PREV_INSN (last_insn
);
2552 && JUMP_P (last_insn
)
2553 && ! simplejump_p (last_insn
))
2557 else_bb
= NULL_BLOCK
;
2563 /* If the THEN block's successor is the other edge out of the TEST block,
2564 then we have an IF-THEN combo without an ELSE. */
2565 else if (single_succ (then_bb
) == else_bb
)
2568 else_bb
= NULL_BLOCK
;
2571 /* If the THEN and ELSE block meet in a subsequent block, and the ELSE
2572 has exactly one predecessor and one successor, and the outgoing edge
2573 is not complex, then we have an IF-THEN-ELSE combo. */
2574 else if (single_succ_p (else_bb
)
2575 && single_succ (then_bb
) == single_succ (else_bb
)
2576 && single_pred_p (else_bb
)
2577 && ! (single_succ_edge (else_bb
)->flags
& EDGE_COMPLEX
)
2578 && ! (flow2_completed
&& tablejump_p (BB_END (else_bb
), NULL
, NULL
)))
2579 join_bb
= single_succ (else_bb
);
2581 /* Otherwise it is not an IF-THEN or IF-THEN-ELSE combination. */
2585 num_possible_if_blocks
++;
2590 "\nIF-THEN%s block found, pass %d, start block %d "
2591 "[insn %d], then %d [%d]",
2592 (else_bb
) ? "-ELSE" : "",
2595 BB_HEAD (test_bb
) ? (int)INSN_UID (BB_HEAD (test_bb
)) : -1,
2597 BB_HEAD (then_bb
) ? (int)INSN_UID (BB_HEAD (then_bb
)) : -1);
2600 fprintf (dump_file
, ", else %d [%d]",
2602 BB_HEAD (else_bb
) ? (int)INSN_UID (BB_HEAD (else_bb
)) : -1);
2604 fprintf (dump_file
, ", join %d [%d]",
2606 BB_HEAD (join_bb
) ? (int)INSN_UID (BB_HEAD (join_bb
)) : -1);
2608 if (ce_info
->num_multiple_test_blocks
> 0)
2609 fprintf (dump_file
, ", %d %s block%s last test %d [%d]",
2610 ce_info
->num_multiple_test_blocks
,
2611 (ce_info
->and_and_p
) ? "&&" : "||",
2612 (ce_info
->num_multiple_test_blocks
== 1) ? "" : "s",
2613 ce_info
->last_test_bb
->index
,
2614 ((BB_HEAD (ce_info
->last_test_bb
))
2615 ? (int)INSN_UID (BB_HEAD (ce_info
->last_test_bb
))
2618 fputc ('\n', dump_file
);
2621 /* Make sure IF, THEN, and ELSE, blocks are adjacent. Actually, we get the
2622 first condition for free, since we've already asserted that there's a
2623 fallthru edge from IF to THEN. Likewise for the && and || blocks, since
2624 we checked the FALLTHRU flag, those are already adjacent to the last IF
2626 /* ??? As an enhancement, move the ELSE block. Have to deal with
2627 BLOCK notes, if by no other means than backing out the merge if they
2628 exist. Sticky enough I don't want to think about it now. */
2630 if (else_bb
&& (next
= next
->next_bb
) != else_bb
)
2632 if ((next
= next
->next_bb
) != join_bb
&& join_bb
!= EXIT_BLOCK_PTR
)
2640 /* Do the real work. */
2641 ce_info
->else_bb
= else_bb
;
2642 ce_info
->join_bb
= join_bb
;
2644 return process_if_block (ce_info
);
2647 /* Convert a branch over a trap, or a branch
2648 to a trap, into a conditional trap. */
2651 find_cond_trap (basic_block test_bb
, edge then_edge
, edge else_edge
)
2653 basic_block then_bb
= then_edge
->dest
;
2654 basic_block else_bb
= else_edge
->dest
;
2655 basic_block other_bb
, trap_bb
;
2656 rtx trap
, jump
, cond
, cond_earliest
, seq
;
2659 /* Locate the block with the trap instruction. */
2660 /* ??? While we look for no successors, we really ought to allow
2661 EH successors. Need to fix merge_if_block for that to work. */
2662 if ((trap
= block_has_only_trap (then_bb
)) != NULL
)
2663 trap_bb
= then_bb
, other_bb
= else_bb
;
2664 else if ((trap
= block_has_only_trap (else_bb
)) != NULL
)
2665 trap_bb
= else_bb
, other_bb
= then_bb
;
2671 fprintf (dump_file
, "\nTRAP-IF block found, start %d, trap %d\n",
2672 test_bb
->index
, trap_bb
->index
);
2675 /* If this is not a standard conditional jump, we can't parse it. */
2676 jump
= BB_END (test_bb
);
2677 cond
= noce_get_condition (jump
, &cond_earliest
);
2681 /* If the conditional jump is more than just a conditional jump, then
2682 we can not do if-conversion on this block. */
2683 if (! onlyjump_p (jump
))
2686 /* We must be comparing objects whose modes imply the size. */
2687 if (GET_MODE (XEXP (cond
, 0)) == BLKmode
)
2690 /* Reverse the comparison code, if necessary. */
2691 code
= GET_CODE (cond
);
2692 if (then_bb
== trap_bb
)
2694 code
= reversed_comparison_code (cond
, jump
);
2695 if (code
== UNKNOWN
)
2699 /* Attempt to generate the conditional trap. */
2700 seq
= gen_cond_trap (code
, XEXP (cond
, 0),
2702 TRAP_CODE (PATTERN (trap
)));
2708 /* Emit the new insns before cond_earliest. */
2709 emit_insn_before_setloc (seq
, cond_earliest
, INSN_LOCATOR (trap
));
2711 /* Delete the trap block if possible. */
2712 remove_edge (trap_bb
== then_bb
? then_edge
: else_edge
);
2713 if (EDGE_COUNT (trap_bb
->preds
) == 0)
2714 delete_basic_block (trap_bb
);
2716 /* If the non-trap block and the test are now adjacent, merge them.
2717 Otherwise we must insert a direct branch. */
2718 if (test_bb
->next_bb
== other_bb
)
2720 struct ce_if_block new_ce_info
;
2722 memset (&new_ce_info
, '\0', sizeof (new_ce_info
));
2723 new_ce_info
.test_bb
= test_bb
;
2724 new_ce_info
.then_bb
= NULL
;
2725 new_ce_info
.else_bb
= NULL
;
2726 new_ce_info
.join_bb
= other_bb
;
2727 merge_if_block (&new_ce_info
);
2733 lab
= JUMP_LABEL (jump
);
2734 newjump
= emit_jump_insn_after (gen_jump (lab
), jump
);
2735 LABEL_NUSES (lab
) += 1;
2736 JUMP_LABEL (newjump
) = lab
;
2737 emit_barrier_after (newjump
);
2745 /* Subroutine of find_cond_trap: if BB contains only a trap insn,
2749 block_has_only_trap (basic_block bb
)
2753 /* We're not the exit block. */
2754 if (bb
== EXIT_BLOCK_PTR
)
2757 /* The block must have no successors. */
2758 if (EDGE_COUNT (bb
->succs
) > 0)
2761 /* The only instruction in the THEN block must be the trap. */
2762 trap
= first_active_insn (bb
);
2763 if (! (trap
== BB_END (bb
)
2764 && GET_CODE (PATTERN (trap
)) == TRAP_IF
2765 && TRAP_CONDITION (PATTERN (trap
)) == const_true_rtx
))
2771 /* Look for IF-THEN-ELSE cases in which one of THEN or ELSE is
2772 transformable, but not necessarily the other. There need be no
2775 Return TRUE if we were successful at converting the block.
2777 Cases we'd like to look at:
2780 if (test) goto over; // x not live
2788 if (! test) goto label;
2791 if (test) goto E; // x not live
2805 (3) // This one's really only interesting for targets that can do
2806 // multiway branching, e.g. IA-64 BBB bundles. For other targets
2807 // it results in multiple branches on a cache line, which often
2808 // does not sit well with predictors.
2810 if (test1) goto E; // predicted not taken
2826 (A) Don't do (2) if the branch is predicted against the block we're
2827 eliminating. Do it anyway if we can eliminate a branch; this requires
2828 that the sole successor of the eliminated block postdominate the other
2831 (B) With CE, on (3) we can steal from both sides of the if, creating
2840 Again, this is most useful if J postdominates.
2842 (C) CE substitutes for helpful life information.
2844 (D) These heuristics need a lot of work. */
2846 /* Tests for case 1 above. */
2849 find_if_case_1 (basic_block test_bb
, edge then_edge
, edge else_edge
)
2851 basic_block then_bb
= then_edge
->dest
;
2852 basic_block else_bb
= else_edge
->dest
, new_bb
;
2855 /* If we are partitioning hot/cold basic blocks, we don't want to
2856 mess up unconditional or indirect jumps that cross between hot
2859 Basic block partitioning may result in some jumps that appear to
2860 be optimizable (or blocks that appear to be mergeable), but which really
2861 must be left untouched (they are required to make it safely across
2862 partition boundaries). See the comments at the top of
2863 bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */
2865 if ((BB_END (then_bb
)
2866 && find_reg_note (BB_END (then_bb
), REG_CROSSING_JUMP
, NULL_RTX
))
2867 || (BB_END (test_bb
)
2868 && find_reg_note (BB_END (test_bb
), REG_CROSSING_JUMP
, NULL_RTX
))
2869 || (BB_END (else_bb
)
2870 && find_reg_note (BB_END (else_bb
), REG_CROSSING_JUMP
,
2874 /* THEN has one successor. */
2875 if (!single_succ_p (then_bb
))
2878 /* THEN does not fall through, but is not strange either. */
2879 if (single_succ_edge (then_bb
)->flags
& (EDGE_COMPLEX
| EDGE_FALLTHRU
))
2882 /* THEN has one predecessor. */
2883 if (!single_pred_p (then_bb
))
2886 /* THEN must do something. */
2887 if (forwarder_block_p (then_bb
))
2890 num_possible_if_blocks
++;
2893 "\nIF-CASE-1 found, start %d, then %d\n",
2894 test_bb
->index
, then_bb
->index
);
2896 /* THEN is small. */
2897 if (! cheap_bb_rtx_cost_p (then_bb
, COSTS_N_INSNS (BRANCH_COST
)))
2900 /* Registers set are dead, or are predicable. */
2901 if (! dead_or_predicable (test_bb
, then_bb
, else_bb
,
2902 single_succ (then_bb
), 1))
2905 /* Conversion went ok, including moving the insns and fixing up the
2906 jump. Adjust the CFG to match. */
2908 bitmap_ior (test_bb
->global_live_at_end
,
2909 else_bb
->global_live_at_start
,
2910 then_bb
->global_live_at_end
);
2913 /* We can avoid creating a new basic block if then_bb is immediately
2914 followed by else_bb, i.e. deleting then_bb allows test_bb to fall
2917 if (then_bb
->next_bb
== else_bb
2918 && then_bb
->prev_bb
== test_bb
2919 && else_bb
!= EXIT_BLOCK_PTR
)
2921 redirect_edge_succ (FALLTHRU_EDGE (test_bb
), else_bb
);
2925 new_bb
= redirect_edge_and_branch_force (FALLTHRU_EDGE (test_bb
),
2928 then_bb_index
= then_bb
->index
;
2929 delete_basic_block (then_bb
);
2931 /* Make rest of code believe that the newly created block is the THEN_BB
2932 block we removed. */
2935 new_bb
->index
= then_bb_index
;
2936 BASIC_BLOCK (then_bb_index
) = new_bb
;
2937 /* Since the fallthru edge was redirected from test_bb to new_bb,
2938 we need to ensure that new_bb is in the same partition as
2939 test bb (you can not fall through across section boundaries). */
2940 BB_COPY_PARTITION (new_bb
, test_bb
);
2942 /* We've possibly created jump to next insn, cleanup_cfg will solve that
2946 num_updated_if_blocks
++;
2951 /* Test for case 2 above. */
2954 find_if_case_2 (basic_block test_bb
, edge then_edge
, edge else_edge
)
2956 basic_block then_bb
= then_edge
->dest
;
2957 basic_block else_bb
= else_edge
->dest
;
2961 /* If we are partitioning hot/cold basic blocks, we don't want to
2962 mess up unconditional or indirect jumps that cross between hot
2965 Basic block partitioning may result in some jumps that appear to
2966 be optimizable (or blocks that appear to be mergeable), but which really
2967 must be left untouched (they are required to make it safely across
2968 partition boundaries). See the comments at the top of
2969 bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */
2971 if ((BB_END (then_bb
)
2972 && find_reg_note (BB_END (then_bb
), REG_CROSSING_JUMP
, NULL_RTX
))
2973 || (BB_END (test_bb
)
2974 && find_reg_note (BB_END (test_bb
), REG_CROSSING_JUMP
, NULL_RTX
))
2975 || (BB_END (else_bb
)
2976 && find_reg_note (BB_END (else_bb
), REG_CROSSING_JUMP
,
2980 /* ELSE has one successor. */
2981 if (!single_succ_p (else_bb
))
2984 else_succ
= single_succ_edge (else_bb
);
2986 /* ELSE outgoing edge is not complex. */
2987 if (else_succ
->flags
& EDGE_COMPLEX
)
2990 /* ELSE has one predecessor. */
2991 if (!single_pred_p (else_bb
))
2994 /* THEN is not EXIT. */
2995 if (then_bb
->index
< 0)
2998 /* ELSE is predicted or SUCC(ELSE) postdominates THEN. */
2999 note
= find_reg_note (BB_END (test_bb
), REG_BR_PROB
, NULL_RTX
);
3000 if (note
&& INTVAL (XEXP (note
, 0)) >= REG_BR_PROB_BASE
/ 2)
3002 else if (else_succ
->dest
->index
< 0
3003 || dominated_by_p (CDI_POST_DOMINATORS
, then_bb
,
3009 num_possible_if_blocks
++;
3012 "\nIF-CASE-2 found, start %d, else %d\n",
3013 test_bb
->index
, else_bb
->index
);
3015 /* ELSE is small. */
3016 if (! cheap_bb_rtx_cost_p (else_bb
, COSTS_N_INSNS (BRANCH_COST
)))
3019 /* Registers set are dead, or are predicable. */
3020 if (! dead_or_predicable (test_bb
, else_bb
, then_bb
, else_succ
->dest
, 0))
3023 /* Conversion went ok, including moving the insns and fixing up the
3024 jump. Adjust the CFG to match. */
3026 bitmap_ior (test_bb
->global_live_at_end
,
3027 then_bb
->global_live_at_start
,
3028 else_bb
->global_live_at_end
);
3030 delete_basic_block (else_bb
);
3033 num_updated_if_blocks
++;
3035 /* ??? We may now fallthru from one of THEN's successors into a join
3036 block. Rerun cleanup_cfg? Examine things manually? Wait? */
3041 /* A subroutine of dead_or_predicable called through for_each_rtx.
3042 Return 1 if a memory is found. */
3045 find_memory (rtx
*px
, void *data ATTRIBUTE_UNUSED
)
3050 /* Used by the code above to perform the actual rtl transformations.
3051 Return TRUE if successful.
3053 TEST_BB is the block containing the conditional branch. MERGE_BB
3054 is the block containing the code to manipulate. NEW_DEST is the
3055 label TEST_BB should be branching to after the conversion.
3056 REVERSEP is true if the sense of the branch should be reversed. */
3059 dead_or_predicable (basic_block test_bb
, basic_block merge_bb
,
3060 basic_block other_bb
, basic_block new_dest
, int reversep
)
3062 rtx head
, end
, jump
, earliest
= NULL_RTX
, old_dest
, new_label
= NULL_RTX
;
3064 jump
= BB_END (test_bb
);
3066 /* Find the extent of the real code in the merge block. */
3067 head
= BB_HEAD (merge_bb
);
3068 end
= BB_END (merge_bb
);
3071 head
= NEXT_INSN (head
);
3076 head
= end
= NULL_RTX
;
3079 head
= NEXT_INSN (head
);
3086 head
= end
= NULL_RTX
;
3089 end
= PREV_INSN (end
);
3092 /* Disable handling dead code by conditional execution if the machine needs
3093 to do anything funny with the tests, etc. */
3094 #ifndef IFCVT_MODIFY_TESTS
3095 if (HAVE_conditional_execution
)
3097 /* In the conditional execution case, we have things easy. We know
3098 the condition is reversible. We don't have to check life info
3099 because we're going to conditionally execute the code anyway.
3100 All that's left is making sure the insns involved can actually
3105 cond
= cond_exec_get_condition (jump
);
3109 prob_val
= find_reg_note (jump
, REG_BR_PROB
, NULL_RTX
);
3111 prob_val
= XEXP (prob_val
, 0);
3115 enum rtx_code rev
= reversed_comparison_code (cond
, jump
);
3118 cond
= gen_rtx_fmt_ee (rev
, GET_MODE (cond
), XEXP (cond
, 0),
3121 prob_val
= GEN_INT (REG_BR_PROB_BASE
- INTVAL (prob_val
));
3124 if (! cond_exec_process_insns ((ce_if_block_t
*)0, head
, end
, cond
,
3133 /* In the non-conditional execution case, we have to verify that there
3134 are no trapping operations, no calls, no references to memory, and
3135 that any registers modified are dead at the branch site. */
3137 rtx insn
, cond
, prev
;
3138 regset merge_set
, tmp
, test_live
, test_set
;
3139 struct propagate_block_info
*pbi
;
3140 unsigned i
, fail
= 0;
3143 /* Check for no calls or trapping operations. */
3144 for (insn
= head
; ; insn
= NEXT_INSN (insn
))
3150 if (may_trap_p (PATTERN (insn
)))
3153 /* ??? Even non-trapping memories such as stack frame
3154 references must be avoided. For stores, we collect
3155 no lifetime info; for reads, we'd have to assert
3156 true_dependence false against every store in the
3158 if (for_each_rtx (&PATTERN (insn
), find_memory
, NULL
))
3165 if (! any_condjump_p (jump
))
3168 /* Find the extent of the conditional. */
3169 cond
= noce_get_condition (jump
, &earliest
);
3174 MERGE_SET = set of registers set in MERGE_BB
3175 TEST_LIVE = set of registers live at EARLIEST
3176 TEST_SET = set of registers set between EARLIEST and the
3177 end of the block. */
3179 tmp
= ALLOC_REG_SET (®_obstack
);
3180 merge_set
= ALLOC_REG_SET (®_obstack
);
3181 test_live
= ALLOC_REG_SET (®_obstack
);
3182 test_set
= ALLOC_REG_SET (®_obstack
);
3184 /* ??? bb->local_set is only valid during calculate_global_regs_live,
3185 so we must recompute usage for MERGE_BB. Not so bad, I suppose,
3186 since we've already asserted that MERGE_BB is small. */
3187 propagate_block (merge_bb
, tmp
, merge_set
, merge_set
, 0);
3189 /* For small register class machines, don't lengthen lifetimes of
3190 hard registers before reload. */
3191 if (SMALL_REGISTER_CLASSES
&& ! reload_completed
)
3193 EXECUTE_IF_SET_IN_BITMAP (merge_set
, 0, i
, bi
)
3195 if (i
< FIRST_PSEUDO_REGISTER
3197 && ! global_regs
[i
])
3202 /* For TEST, we're interested in a range of insns, not a whole block.
3203 Moreover, we're interested in the insns live from OTHER_BB. */
3205 COPY_REG_SET (test_live
, other_bb
->global_live_at_start
);
3206 pbi
= init_propagate_block_info (test_bb
, test_live
, test_set
, test_set
,
3209 for (insn
= jump
; ; insn
= prev
)
3211 prev
= propagate_one_insn (pbi
, insn
);
3212 if (insn
== earliest
)
3216 free_propagate_block_info (pbi
);
3218 /* We can perform the transformation if
3219 MERGE_SET & (TEST_SET | TEST_LIVE)
3221 TEST_SET & merge_bb->global_live_at_start
3224 if (bitmap_intersect_p (test_set
, merge_set
)
3225 || bitmap_intersect_p (test_live
, merge_set
)
3226 || bitmap_intersect_p (test_set
, merge_bb
->global_live_at_start
))
3230 FREE_REG_SET (merge_set
);
3231 FREE_REG_SET (test_live
);
3232 FREE_REG_SET (test_set
);
3239 /* We don't want to use normal invert_jump or redirect_jump because
3240 we don't want to delete_insn called. Also, we want to do our own
3241 change group management. */
3243 old_dest
= JUMP_LABEL (jump
);
3244 if (other_bb
!= new_dest
)
3246 new_label
= block_label (new_dest
);
3248 ? ! invert_jump_1 (jump
, new_label
)
3249 : ! redirect_jump_1 (jump
, new_label
))
3253 if (! apply_change_group ())
3256 if (other_bb
!= new_dest
)
3258 redirect_jump_2 (jump
, old_dest
, new_label
, -1, reversep
);
3260 redirect_edge_succ (BRANCH_EDGE (test_bb
), new_dest
);
3263 gcov_type count
, probability
;
3264 count
= BRANCH_EDGE (test_bb
)->count
;
3265 BRANCH_EDGE (test_bb
)->count
= FALLTHRU_EDGE (test_bb
)->count
;
3266 FALLTHRU_EDGE (test_bb
)->count
= count
;
3267 probability
= BRANCH_EDGE (test_bb
)->probability
;
3268 BRANCH_EDGE (test_bb
)->probability
3269 = FALLTHRU_EDGE (test_bb
)->probability
;
3270 FALLTHRU_EDGE (test_bb
)->probability
= probability
;
3271 update_br_prob_note (test_bb
);
3275 /* Move the insns out of MERGE_BB to before the branch. */
3278 if (end
== BB_END (merge_bb
))
3279 BB_END (merge_bb
) = PREV_INSN (head
);
3281 if (squeeze_notes (&head
, &end
))
3284 reorder_insns (head
, end
, PREV_INSN (earliest
));
3287 /* Remove the jump and edge if we can. */
3288 if (other_bb
== new_dest
)
3291 remove_edge (BRANCH_EDGE (test_bb
));
3292 /* ??? Can't merge blocks here, as then_bb is still in use.
3293 At minimum, the merge will get done just before bb-reorder. */
3303 /* Main entry point for all if-conversion. */
3306 if_convert (int x_life_data_ok
)
3311 num_possible_if_blocks
= 0;
3312 num_updated_if_blocks
= 0;
3313 num_true_changes
= 0;
3314 life_data_ok
= (x_life_data_ok
!= 0);
3316 if ((! targetm
.cannot_modify_jumps_p ())
3317 && (!flag_reorder_blocks_and_partition
|| !no_new_pseudos
3318 || !targetm
.have_named_sections
))
3322 flow_loops_find (&loops
);
3323 mark_loop_exit_edges (&loops
);
3324 flow_loops_free (&loops
);
3325 free_dominance_info (CDI_DOMINATORS
);
3328 /* Compute postdominators if we think we'll use them. */
3329 if (HAVE_conditional_execution
|| life_data_ok
)
3330 calculate_dominance_info (CDI_POST_DOMINATORS
);
3335 /* Go through each of the basic blocks looking for things to convert. If we
3336 have conditional execution, we make multiple passes to allow us to handle
3337 IF-THEN{-ELSE} blocks within other IF-THEN{-ELSE} blocks. */
3341 cond_exec_changed_p
= FALSE
;
3344 #ifdef IFCVT_MULTIPLE_DUMPS
3345 if (dump_file
&& pass
> 1)
3346 fprintf (dump_file
, "\n\n========== Pass %d ==========\n", pass
);
3352 while ((new_bb
= find_if_header (bb
, pass
)))
3356 #ifdef IFCVT_MULTIPLE_DUMPS
3357 if (dump_file
&& cond_exec_changed_p
)
3358 print_rtl_with_bb (dump_file
, get_insns ());
3361 while (cond_exec_changed_p
);
3363 #ifdef IFCVT_MULTIPLE_DUMPS
3365 fprintf (dump_file
, "\n\n========== no more changes\n");
3368 free_dominance_info (CDI_POST_DOMINATORS
);
3373 clear_aux_for_blocks ();
3375 /* Rebuild life info for basic blocks that require it. */
3376 if (num_true_changes
&& life_data_ok
)
3378 /* If we allocated new pseudos, we must resize the array for sched1. */
3379 if (max_regno
< max_reg_num ())
3381 max_regno
= max_reg_num ();
3382 allocate_reg_info (max_regno
, FALSE
, FALSE
);
3384 update_life_info_in_dirty_blocks (UPDATE_LIFE_GLOBAL_RM_NOTES
,
3385 PROP_DEATH_NOTES
| PROP_SCAN_DEAD_CODE
3386 | PROP_KILL_DEAD_CODE
);
3389 /* Write the final stats. */
3390 if (dump_file
&& num_possible_if_blocks
> 0)
3393 "\n%d possible IF blocks searched.\n",
3394 num_possible_if_blocks
);
3396 "%d IF blocks converted.\n",
3397 num_updated_if_blocks
);
3399 "%d true changes made.\n\n\n",
3403 #ifdef ENABLE_CHECKING
3404 verify_flow_info ();