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_EDGE ((edge) NULL)
70 #define NULL_BLOCK ((basic_block) NULL)
72 /* # of IF-THEN or IF-THEN-ELSE blocks we looked at */
73 static int num_possible_if_blocks
;
75 /* # of IF-THEN or IF-THEN-ELSE blocks were converted to conditional
77 static int num_updated_if_blocks
;
79 /* # of changes made which require life information to be updated. */
80 static int num_true_changes
;
82 /* Whether conditional execution changes were made. */
83 static int cond_exec_changed_p
;
85 /* True if life data ok at present. */
86 static bool life_data_ok
;
88 /* Forward references. */
89 static int count_bb_insns (basic_block
);
90 static bool cheap_bb_rtx_cost_p (basic_block
, int);
91 static rtx
first_active_insn (basic_block
);
92 static rtx
last_active_insn (basic_block
, int);
93 static basic_block
block_fallthru (basic_block
);
94 static int cond_exec_process_insns (ce_if_block_t
*, rtx
, rtx
, rtx
, rtx
, int);
95 static rtx
cond_exec_get_condition (rtx
);
96 static int cond_exec_process_if_block (ce_if_block_t
*, int);
97 static rtx
noce_get_condition (rtx
, rtx
*);
98 static int noce_operand_ok (rtx
);
99 static int noce_process_if_block (ce_if_block_t
*);
100 static int process_if_block (ce_if_block_t
*);
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 find_if_block (ce_if_block_t
*);
106 static int find_if_case_1 (basic_block
, edge
, edge
);
107 static int find_if_case_2 (basic_block
, edge
, edge
);
108 static int find_memory (rtx
*, void *);
109 static int dead_or_predicable (basic_block
, basic_block
, basic_block
,
111 static void noce_emit_move_insn (rtx
, rtx
);
112 static rtx
block_has_only_trap (basic_block
);
114 /* Count the number of non-jump active insns in BB. */
117 count_bb_insns (basic_block bb
)
120 rtx insn
= BB_HEAD (bb
);
124 if (CALL_P (insn
) || NONJUMP_INSN_P (insn
))
127 if (insn
== BB_END (bb
))
129 insn
= NEXT_INSN (insn
);
135 /* Determine whether the total insn_rtx_cost on non-jump insns in
136 basic block BB is less than MAX_COST. This function returns
137 false if the cost of any instruction could not be estimated. */
140 cheap_bb_rtx_cost_p (basic_block bb
, int max_cost
)
143 rtx insn
= BB_HEAD (bb
);
147 if (NONJUMP_INSN_P (insn
))
149 int cost
= insn_rtx_cost (PATTERN (insn
));
153 /* If this instruction is the load or set of a "stack" register,
154 such as a floating point register on x87, then the cost of
155 speculatively executing this instruction needs to include
156 the additional cost of popping this register off of the
160 rtx set
= single_set (insn
);
161 if (set
&& STACK_REG_P (SET_DEST (set
)))
162 cost
+= COSTS_N_INSNS (1);
167 if (count
>= max_cost
)
170 else if (CALL_P (insn
))
173 if (insn
== BB_END (bb
))
175 insn
= NEXT_INSN (insn
);
181 /* Return the first non-jump active insn in the basic block. */
184 first_active_insn (basic_block bb
)
186 rtx insn
= BB_HEAD (bb
);
190 if (insn
== BB_END (bb
))
192 insn
= NEXT_INSN (insn
);
195 while (NOTE_P (insn
))
197 if (insn
== BB_END (bb
))
199 insn
= NEXT_INSN (insn
);
208 /* Return the last non-jump active (non-jump) insn in the basic block. */
211 last_active_insn (basic_block bb
, int skip_use_p
)
213 rtx insn
= BB_END (bb
);
214 rtx head
= BB_HEAD (bb
);
219 && NONJUMP_INSN_P (insn
)
220 && GET_CODE (PATTERN (insn
)) == USE
))
224 insn
= PREV_INSN (insn
);
233 /* Return the basic block reached by falling though the basic block BB. */
236 block_fallthru (basic_block bb
)
241 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
242 if (e
->flags
& EDGE_FALLTHRU
)
245 return (e
) ? e
->dest
: NULL_BLOCK
;
248 /* Go through a bunch of insns, converting them to conditional
249 execution format if possible. Return TRUE if all of the non-note
250 insns were processed. */
253 cond_exec_process_insns (ce_if_block_t
*ce_info ATTRIBUTE_UNUSED
,
254 /* if block information */rtx start
,
255 /* first insn to look at */rtx end
,
256 /* last insn to look at */rtx test
,
257 /* conditional execution test */rtx prob_val
,
258 /* probability of branch taken. */int mod_ok
)
260 int must_be_last
= FALSE
;
268 for (insn
= start
; ; insn
= NEXT_INSN (insn
))
273 if (!NONJUMP_INSN_P (insn
) && !CALL_P (insn
))
276 /* Remove USE insns that get in the way. */
277 if (reload_completed
&& GET_CODE (PATTERN (insn
)) == USE
)
279 /* ??? Ug. Actually unlinking the thing is problematic,
280 given what we'd have to coordinate with our callers. */
281 SET_INSN_DELETED (insn
);
285 /* Last insn wasn't last? */
289 if (modified_in_p (test
, insn
))
296 /* Now build the conditional form of the instruction. */
297 pattern
= PATTERN (insn
);
298 xtest
= copy_rtx (test
);
300 /* If this is already a COND_EXEC, rewrite the test to be an AND of the
302 if (GET_CODE (pattern
) == COND_EXEC
)
304 if (GET_MODE (xtest
) != GET_MODE (COND_EXEC_TEST (pattern
)))
307 xtest
= gen_rtx_AND (GET_MODE (xtest
), xtest
,
308 COND_EXEC_TEST (pattern
));
309 pattern
= COND_EXEC_CODE (pattern
);
312 pattern
= gen_rtx_COND_EXEC (VOIDmode
, xtest
, pattern
);
314 /* If the machine needs to modify the insn being conditionally executed,
315 say for example to force a constant integer operand into a temp
316 register, do so here. */
317 #ifdef IFCVT_MODIFY_INSN
318 IFCVT_MODIFY_INSN (ce_info
, pattern
, insn
);
323 validate_change (insn
, &PATTERN (insn
), pattern
, 1);
325 if (CALL_P (insn
) && prob_val
)
326 validate_change (insn
, ®_NOTES (insn
),
327 alloc_EXPR_LIST (REG_BR_PROB
, prob_val
,
328 REG_NOTES (insn
)), 1);
338 /* Return the condition for a jump. Do not do any special processing. */
341 cond_exec_get_condition (rtx jump
)
345 if (any_condjump_p (jump
))
346 test_if
= SET_SRC (pc_set (jump
));
349 cond
= XEXP (test_if
, 0);
351 /* If this branches to JUMP_LABEL when the condition is false,
352 reverse the condition. */
353 if (GET_CODE (XEXP (test_if
, 2)) == LABEL_REF
354 && XEXP (XEXP (test_if
, 2), 0) == JUMP_LABEL (jump
))
356 enum rtx_code rev
= reversed_comparison_code (cond
, jump
);
360 cond
= gen_rtx_fmt_ee (rev
, GET_MODE (cond
), XEXP (cond
, 0),
367 /* Given a simple IF-THEN or IF-THEN-ELSE block, attempt to convert it
368 to conditional execution. Return TRUE if we were successful at
369 converting the block. */
372 cond_exec_process_if_block (ce_if_block_t
* ce_info
,
373 /* if block information */int do_multiple_p
)
375 basic_block test_bb
= ce_info
->test_bb
; /* last test block */
376 basic_block then_bb
= ce_info
->then_bb
; /* THEN */
377 basic_block else_bb
= ce_info
->else_bb
; /* ELSE or NULL */
378 rtx test_expr
; /* expression in IF_THEN_ELSE that is tested */
379 rtx then_start
; /* first insn in THEN block */
380 rtx then_end
; /* last insn + 1 in THEN block */
381 rtx else_start
= NULL_RTX
; /* first insn in ELSE block or NULL */
382 rtx else_end
= NULL_RTX
; /* last insn + 1 in ELSE block */
383 int max
; /* max # of insns to convert. */
384 int then_mod_ok
; /* whether conditional mods are ok in THEN */
385 rtx true_expr
; /* test for else block insns */
386 rtx false_expr
; /* test for then block insns */
387 rtx true_prob_val
; /* probability of else block */
388 rtx false_prob_val
; /* probability of then block */
390 enum rtx_code false_code
;
392 /* If test is comprised of && or || elements, and we've failed at handling
393 all of them together, just use the last test if it is the special case of
394 && elements without an ELSE block. */
395 if (!do_multiple_p
&& ce_info
->num_multiple_test_blocks
)
397 if (else_bb
|| ! ce_info
->and_and_p
)
400 ce_info
->test_bb
= test_bb
= ce_info
->last_test_bb
;
401 ce_info
->num_multiple_test_blocks
= 0;
402 ce_info
->num_and_and_blocks
= 0;
403 ce_info
->num_or_or_blocks
= 0;
406 /* Find the conditional jump to the ELSE or JOIN part, and isolate
408 test_expr
= cond_exec_get_condition (BB_END (test_bb
));
412 /* If the conditional jump is more than just a conditional jump,
413 then we can not do conditional execution conversion on this block. */
414 if (! onlyjump_p (BB_END (test_bb
)))
417 /* Collect the bounds of where we're to search, skipping any labels, jumps
418 and notes at the beginning and end of the block. Then count the total
419 number of insns and see if it is small enough to convert. */
420 then_start
= first_active_insn (then_bb
);
421 then_end
= last_active_insn (then_bb
, TRUE
);
422 n_insns
= ce_info
->num_then_insns
= count_bb_insns (then_bb
);
423 max
= MAX_CONDITIONAL_EXECUTE
;
428 else_start
= first_active_insn (else_bb
);
429 else_end
= last_active_insn (else_bb
, TRUE
);
430 n_insns
+= ce_info
->num_else_insns
= count_bb_insns (else_bb
);
436 /* Map test_expr/test_jump into the appropriate MD tests to use on
437 the conditionally executed code. */
439 true_expr
= test_expr
;
441 false_code
= reversed_comparison_code (true_expr
, BB_END (test_bb
));
442 if (false_code
!= UNKNOWN
)
443 false_expr
= gen_rtx_fmt_ee (false_code
, GET_MODE (true_expr
),
444 XEXP (true_expr
, 0), XEXP (true_expr
, 1));
446 false_expr
= NULL_RTX
;
448 #ifdef IFCVT_MODIFY_TESTS
449 /* If the machine description needs to modify the tests, such as setting a
450 conditional execution register from a comparison, it can do so here. */
451 IFCVT_MODIFY_TESTS (ce_info
, true_expr
, false_expr
);
453 /* See if the conversion failed. */
454 if (!true_expr
|| !false_expr
)
458 true_prob_val
= find_reg_note (BB_END (test_bb
), REG_BR_PROB
, NULL_RTX
);
461 true_prob_val
= XEXP (true_prob_val
, 0);
462 false_prob_val
= GEN_INT (REG_BR_PROB_BASE
- INTVAL (true_prob_val
));
465 false_prob_val
= NULL_RTX
;
467 /* If we have && or || tests, do them here. These tests are in the adjacent
468 blocks after the first block containing the test. */
469 if (ce_info
->num_multiple_test_blocks
> 0)
471 basic_block bb
= test_bb
;
472 basic_block last_test_bb
= ce_info
->last_test_bb
;
481 enum rtx_code f_code
;
483 bb
= block_fallthru (bb
);
484 start
= first_active_insn (bb
);
485 end
= last_active_insn (bb
, TRUE
);
487 && ! cond_exec_process_insns (ce_info
, start
, end
, false_expr
,
488 false_prob_val
, FALSE
))
491 /* If the conditional jump is more than just a conditional jump, then
492 we can not do conditional execution conversion on this block. */
493 if (! onlyjump_p (BB_END (bb
)))
496 /* Find the conditional jump and isolate the test. */
497 t
= cond_exec_get_condition (BB_END (bb
));
501 f_code
= reversed_comparison_code (t
, BB_END (bb
));
502 if (f_code
== UNKNOWN
)
505 f
= gen_rtx_fmt_ee (f_code
, GET_MODE (t
), XEXP (t
, 0), XEXP (t
, 1));
506 if (ce_info
->and_and_p
)
508 t
= gen_rtx_AND (GET_MODE (t
), true_expr
, t
);
509 f
= gen_rtx_IOR (GET_MODE (t
), false_expr
, f
);
513 t
= gen_rtx_IOR (GET_MODE (t
), true_expr
, t
);
514 f
= gen_rtx_AND (GET_MODE (t
), false_expr
, f
);
517 /* If the machine description needs to modify the tests, such as
518 setting a conditional execution register from a comparison, it can
520 #ifdef IFCVT_MODIFY_MULTIPLE_TESTS
521 IFCVT_MODIFY_MULTIPLE_TESTS (ce_info
, bb
, t
, f
);
523 /* See if the conversion failed. */
531 while (bb
!= last_test_bb
);
534 /* For IF-THEN-ELSE blocks, we don't allow modifications of the test
535 on then THEN block. */
536 then_mod_ok
= (else_bb
== NULL_BLOCK
);
538 /* Go through the THEN and ELSE blocks converting the insns if possible
539 to conditional execution. */
543 || ! cond_exec_process_insns (ce_info
, then_start
, then_end
,
544 false_expr
, false_prob_val
,
548 if (else_bb
&& else_end
549 && ! cond_exec_process_insns (ce_info
, else_start
, else_end
,
550 true_expr
, true_prob_val
, TRUE
))
553 /* If we cannot apply the changes, fail. Do not go through the normal fail
554 processing, since apply_change_group will call cancel_changes. */
555 if (! apply_change_group ())
557 #ifdef IFCVT_MODIFY_CANCEL
558 /* Cancel any machine dependent changes. */
559 IFCVT_MODIFY_CANCEL (ce_info
);
564 #ifdef IFCVT_MODIFY_FINAL
565 /* Do any machine dependent final modifications. */
566 IFCVT_MODIFY_FINAL (ce_info
);
569 /* Conversion succeeded. */
571 fprintf (dump_file
, "%d insn%s converted to conditional execution.\n",
572 n_insns
, (n_insns
== 1) ? " was" : "s were");
574 /* Merge the blocks! */
575 merge_if_block (ce_info
);
576 cond_exec_changed_p
= TRUE
;
580 #ifdef IFCVT_MODIFY_CANCEL
581 /* Cancel any machine dependent changes. */
582 IFCVT_MODIFY_CANCEL (ce_info
);
589 /* Used by noce_process_if_block to communicate with its subroutines.
591 The subroutines know that A and B may be evaluated freely. They
592 know that X is a register. They should insert new instructions
593 before cond_earliest. */
600 rtx jump
, cond
, cond_earliest
;
601 /* True if "b" was originally evaluated unconditionally. */
602 bool b_unconditional
;
605 static rtx
noce_emit_store_flag (struct noce_if_info
*, rtx
, int, int);
606 static int noce_try_move (struct noce_if_info
*);
607 static int noce_try_store_flag (struct noce_if_info
*);
608 static int noce_try_addcc (struct noce_if_info
*);
609 static int noce_try_store_flag_constants (struct noce_if_info
*);
610 static int noce_try_store_flag_mask (struct noce_if_info
*);
611 static rtx
noce_emit_cmove (struct noce_if_info
*, rtx
, enum rtx_code
, rtx
,
613 static int noce_try_cmove (struct noce_if_info
*);
614 static int noce_try_cmove_arith (struct noce_if_info
*);
615 static rtx
noce_get_alt_condition (struct noce_if_info
*, rtx
, rtx
*);
616 static int noce_try_minmax (struct noce_if_info
*);
617 static int noce_try_abs (struct noce_if_info
*);
618 static int noce_try_sign_mask (struct noce_if_info
*);
620 /* Helper function for noce_try_store_flag*. */
623 noce_emit_store_flag (struct noce_if_info
*if_info
, rtx x
, int reversep
,
626 rtx cond
= if_info
->cond
;
630 cond_complex
= (! general_operand (XEXP (cond
, 0), VOIDmode
)
631 || ! general_operand (XEXP (cond
, 1), VOIDmode
));
633 /* If earliest == jump, or when the condition is complex, try to
634 build the store_flag insn directly. */
637 cond
= XEXP (SET_SRC (pc_set (if_info
->jump
)), 0);
640 code
= reversed_comparison_code (cond
, if_info
->jump
);
642 code
= GET_CODE (cond
);
644 if ((if_info
->cond_earliest
== if_info
->jump
|| cond_complex
)
645 && (normalize
== 0 || STORE_FLAG_VALUE
== normalize
))
649 tmp
= gen_rtx_fmt_ee (code
, GET_MODE (x
), XEXP (cond
, 0),
651 tmp
= gen_rtx_SET (VOIDmode
, x
, tmp
);
654 tmp
= emit_insn (tmp
);
656 if (recog_memoized (tmp
) >= 0)
662 if_info
->cond_earliest
= if_info
->jump
;
670 /* Don't even try if the comparison operands or the mode of X are weird. */
671 if (cond_complex
|| !SCALAR_INT_MODE_P (GET_MODE (x
)))
674 return emit_store_flag (x
, code
, XEXP (cond
, 0),
675 XEXP (cond
, 1), VOIDmode
,
676 (code
== LTU
|| code
== LEU
677 || code
== GEU
|| code
== GTU
), normalize
);
680 /* Emit instruction to move an rtx, possibly into STRICT_LOW_PART.
681 X is the destination/target and Y is the value to copy. */
684 noce_emit_move_insn (rtx x
, rtx y
)
686 enum machine_mode outmode
;
690 if (GET_CODE (x
) != STRICT_LOW_PART
)
692 emit_move_insn (x
, y
);
697 inner
= XEXP (outer
, 0);
698 outmode
= GET_MODE (outer
);
699 bitpos
= SUBREG_BYTE (outer
) * BITS_PER_UNIT
;
700 store_bit_field (inner
, GET_MODE_BITSIZE (outmode
), bitpos
, outmode
, y
);
703 /* Return sequence of instructions generated by if conversion. This
704 function calls end_sequence() to end the current stream, ensures
705 that are instructions are unshared, recognizable non-jump insns.
706 On failure, this function returns a NULL_RTX. */
709 end_ifcvt_sequence (struct noce_if_info
*if_info
)
712 rtx seq
= get_insns ();
714 set_used_flags (if_info
->x
);
715 set_used_flags (if_info
->cond
);
716 unshare_all_rtl_in_chain (seq
);
719 /* Make sure that all of the instructions emitted are recognizable,
720 and that we haven't introduced a new jump instruction.
721 As an exercise for the reader, build a general mechanism that
722 allows proper placement of required clobbers. */
723 for (insn
= seq
; insn
; insn
= NEXT_INSN (insn
))
725 || recog_memoized (insn
) == -1)
731 /* Convert "if (a != b) x = a; else x = b" into "x = a" and
732 "if (a == b) x = a; else x = b" into "x = b". */
735 noce_try_move (struct noce_if_info
*if_info
)
737 rtx cond
= if_info
->cond
;
738 enum rtx_code code
= GET_CODE (cond
);
741 if (code
!= NE
&& code
!= EQ
)
744 /* This optimization isn't valid if either A or B could be a NaN
746 if (HONOR_NANS (GET_MODE (if_info
->x
))
747 || HONOR_SIGNED_ZEROS (GET_MODE (if_info
->x
)))
750 /* Check whether the operands of the comparison are A and in
752 if ((rtx_equal_p (if_info
->a
, XEXP (cond
, 0))
753 && rtx_equal_p (if_info
->b
, XEXP (cond
, 1)))
754 || (rtx_equal_p (if_info
->a
, XEXP (cond
, 1))
755 && rtx_equal_p (if_info
->b
, XEXP (cond
, 0))))
757 y
= (code
== EQ
) ? if_info
->a
: if_info
->b
;
759 /* Avoid generating the move if the source is the destination. */
760 if (! rtx_equal_p (if_info
->x
, y
))
763 noce_emit_move_insn (if_info
->x
, y
);
764 seq
= end_ifcvt_sequence (if_info
);
768 emit_insn_before_setloc (seq
, if_info
->jump
,
769 INSN_LOCATOR (if_info
->insn_a
));
776 /* Convert "if (test) x = 1; else x = 0".
778 Only try 0 and STORE_FLAG_VALUE here. Other combinations will be
779 tried in noce_try_store_flag_constants after noce_try_cmove has had
780 a go at the conversion. */
783 noce_try_store_flag (struct noce_if_info
*if_info
)
788 if (GET_CODE (if_info
->b
) == CONST_INT
789 && INTVAL (if_info
->b
) == STORE_FLAG_VALUE
790 && if_info
->a
== const0_rtx
)
792 else if (if_info
->b
== const0_rtx
793 && GET_CODE (if_info
->a
) == CONST_INT
794 && INTVAL (if_info
->a
) == STORE_FLAG_VALUE
795 && (reversed_comparison_code (if_info
->cond
, if_info
->jump
)
803 target
= noce_emit_store_flag (if_info
, if_info
->x
, reversep
, 0);
806 if (target
!= if_info
->x
)
807 noce_emit_move_insn (if_info
->x
, target
);
809 seq
= end_ifcvt_sequence (if_info
);
813 emit_insn_before_setloc (seq
, if_info
->jump
,
814 INSN_LOCATOR (if_info
->insn_a
));
824 /* Convert "if (test) x = a; else x = b", for A and B constant. */
827 noce_try_store_flag_constants (struct noce_if_info
*if_info
)
831 HOST_WIDE_INT itrue
, ifalse
, diff
, tmp
;
832 int normalize
, can_reverse
;
833 enum machine_mode mode
;
836 && GET_CODE (if_info
->a
) == CONST_INT
837 && GET_CODE (if_info
->b
) == CONST_INT
)
839 mode
= GET_MODE (if_info
->x
);
840 ifalse
= INTVAL (if_info
->a
);
841 itrue
= INTVAL (if_info
->b
);
843 /* Make sure we can represent the difference between the two values. */
844 if ((itrue
- ifalse
> 0)
845 != ((ifalse
< 0) != (itrue
< 0) ? ifalse
< 0 : ifalse
< itrue
))
848 diff
= trunc_int_for_mode (itrue
- ifalse
, mode
);
850 can_reverse
= (reversed_comparison_code (if_info
->cond
, if_info
->jump
)
854 if (diff
== STORE_FLAG_VALUE
|| diff
== -STORE_FLAG_VALUE
)
856 else if (ifalse
== 0 && exact_log2 (itrue
) >= 0
857 && (STORE_FLAG_VALUE
== 1
858 || BRANCH_COST
>= 2))
860 else if (itrue
== 0 && exact_log2 (ifalse
) >= 0 && can_reverse
861 && (STORE_FLAG_VALUE
== 1 || BRANCH_COST
>= 2))
862 normalize
= 1, reversep
= 1;
864 && (STORE_FLAG_VALUE
== -1
865 || BRANCH_COST
>= 2))
867 else if (ifalse
== -1 && can_reverse
868 && (STORE_FLAG_VALUE
== -1 || BRANCH_COST
>= 2))
869 normalize
= -1, reversep
= 1;
870 else if ((BRANCH_COST
>= 2 && STORE_FLAG_VALUE
== -1)
878 tmp
= itrue
; itrue
= ifalse
; ifalse
= tmp
;
879 diff
= trunc_int_for_mode (-diff
, mode
);
883 target
= noce_emit_store_flag (if_info
, if_info
->x
, reversep
, normalize
);
890 /* if (test) x = 3; else x = 4;
891 => x = 3 + (test == 0); */
892 if (diff
== STORE_FLAG_VALUE
|| diff
== -STORE_FLAG_VALUE
)
894 target
= expand_simple_binop (mode
,
895 (diff
== STORE_FLAG_VALUE
897 GEN_INT (ifalse
), target
, if_info
->x
, 0,
901 /* if (test) x = 8; else x = 0;
902 => x = (test != 0) << 3; */
903 else if (ifalse
== 0 && (tmp
= exact_log2 (itrue
)) >= 0)
905 target
= expand_simple_binop (mode
, ASHIFT
,
906 target
, GEN_INT (tmp
), if_info
->x
, 0,
910 /* if (test) x = -1; else x = b;
911 => x = -(test != 0) | b; */
912 else if (itrue
== -1)
914 target
= expand_simple_binop (mode
, IOR
,
915 target
, GEN_INT (ifalse
), if_info
->x
, 0,
919 /* if (test) x = a; else x = b;
920 => x = (-(test != 0) & (b - a)) + a; */
923 target
= expand_simple_binop (mode
, AND
,
924 target
, GEN_INT (diff
), if_info
->x
, 0,
927 target
= expand_simple_binop (mode
, PLUS
,
928 target
, GEN_INT (ifalse
),
929 if_info
->x
, 0, OPTAB_WIDEN
);
938 if (target
!= if_info
->x
)
939 noce_emit_move_insn (if_info
->x
, target
);
941 seq
= end_ifcvt_sequence (if_info
);
945 emit_insn_before_setloc (seq
, if_info
->jump
,
946 INSN_LOCATOR (if_info
->insn_a
));
953 /* Convert "if (test) foo++" into "foo += (test != 0)", and
954 similarly for "foo--". */
957 noce_try_addcc (struct noce_if_info
*if_info
)
960 int subtract
, normalize
;
963 && GET_CODE (if_info
->a
) == PLUS
964 && rtx_equal_p (XEXP (if_info
->a
, 0), if_info
->b
)
965 && (reversed_comparison_code (if_info
->cond
, if_info
->jump
)
968 rtx cond
= if_info
->cond
;
969 enum rtx_code code
= reversed_comparison_code (cond
, if_info
->jump
);
971 /* First try to use addcc pattern. */
972 if (general_operand (XEXP (cond
, 0), VOIDmode
)
973 && general_operand (XEXP (cond
, 1), VOIDmode
))
976 target
= emit_conditional_add (if_info
->x
, code
,
981 XEXP (if_info
->a
, 1),
982 GET_MODE (if_info
->x
),
983 (code
== LTU
|| code
== GEU
984 || code
== LEU
|| code
== GTU
));
987 if (target
!= if_info
->x
)
988 noce_emit_move_insn (if_info
->x
, target
);
990 seq
= end_ifcvt_sequence (if_info
);
994 emit_insn_before_setloc (seq
, if_info
->jump
,
995 INSN_LOCATOR (if_info
->insn_a
));
1001 /* If that fails, construct conditional increment or decrement using
1003 if (BRANCH_COST
>= 2
1004 && (XEXP (if_info
->a
, 1) == const1_rtx
1005 || XEXP (if_info
->a
, 1) == constm1_rtx
))
1008 if (STORE_FLAG_VALUE
== INTVAL (XEXP (if_info
->a
, 1)))
1009 subtract
= 0, normalize
= 0;
1010 else if (-STORE_FLAG_VALUE
== INTVAL (XEXP (if_info
->a
, 1)))
1011 subtract
= 1, normalize
= 0;
1013 subtract
= 0, normalize
= INTVAL (XEXP (if_info
->a
, 1));
1016 target
= noce_emit_store_flag (if_info
,
1017 gen_reg_rtx (GET_MODE (if_info
->x
)),
1021 target
= expand_simple_binop (GET_MODE (if_info
->x
),
1022 subtract
? MINUS
: PLUS
,
1023 if_info
->b
, target
, if_info
->x
,
1027 if (target
!= if_info
->x
)
1028 noce_emit_move_insn (if_info
->x
, target
);
1030 seq
= end_ifcvt_sequence (if_info
);
1034 emit_insn_before_setloc (seq
, if_info
->jump
,
1035 INSN_LOCATOR (if_info
->insn_a
));
1045 /* Convert "if (test) x = 0;" to "x &= -(test == 0);" */
1048 noce_try_store_flag_mask (struct noce_if_info
*if_info
)
1054 if (! no_new_pseudos
1055 && (BRANCH_COST
>= 2
1056 || STORE_FLAG_VALUE
== -1)
1057 && ((if_info
->a
== const0_rtx
1058 && rtx_equal_p (if_info
->b
, if_info
->x
))
1059 || ((reversep
= (reversed_comparison_code (if_info
->cond
,
1062 && if_info
->b
== const0_rtx
1063 && rtx_equal_p (if_info
->a
, if_info
->x
))))
1066 target
= noce_emit_store_flag (if_info
,
1067 gen_reg_rtx (GET_MODE (if_info
->x
)),
1070 target
= expand_simple_binop (GET_MODE (if_info
->x
), AND
,
1072 target
, if_info
->x
, 0,
1077 if (target
!= if_info
->x
)
1078 noce_emit_move_insn (if_info
->x
, target
);
1080 seq
= end_ifcvt_sequence (if_info
);
1084 emit_insn_before_setloc (seq
, if_info
->jump
,
1085 INSN_LOCATOR (if_info
->insn_a
));
1095 /* Helper function for noce_try_cmove and noce_try_cmove_arith. */
1098 noce_emit_cmove (struct noce_if_info
*if_info
, rtx x
, enum rtx_code code
,
1099 rtx cmp_a
, rtx cmp_b
, rtx vfalse
, rtx vtrue
)
1101 /* If earliest == jump, try to build the cmove insn directly.
1102 This is helpful when combine has created some complex condition
1103 (like for alpha's cmovlbs) that we can't hope to regenerate
1104 through the normal interface. */
1106 if (if_info
->cond_earliest
== if_info
->jump
)
1110 tmp
= gen_rtx_fmt_ee (code
, GET_MODE (if_info
->cond
), cmp_a
, cmp_b
);
1111 tmp
= gen_rtx_IF_THEN_ELSE (GET_MODE (x
), tmp
, vtrue
, vfalse
);
1112 tmp
= gen_rtx_SET (VOIDmode
, x
, tmp
);
1115 tmp
= emit_insn (tmp
);
1117 if (recog_memoized (tmp
) >= 0)
1129 /* Don't even try if the comparison operands are weird. */
1130 if (! general_operand (cmp_a
, GET_MODE (cmp_a
))
1131 || ! general_operand (cmp_b
, GET_MODE (cmp_b
)))
1134 #if HAVE_conditional_move
1135 return emit_conditional_move (x
, code
, cmp_a
, cmp_b
, VOIDmode
,
1136 vtrue
, vfalse
, GET_MODE (x
),
1137 (code
== LTU
|| code
== GEU
1138 || code
== LEU
|| code
== GTU
));
1140 /* We'll never get here, as noce_process_if_block doesn't call the
1141 functions involved. Ifdef code, however, should be discouraged
1142 because it leads to typos in the code not selected. However,
1143 emit_conditional_move won't exist either. */
1148 /* Try only simple constants and registers here. More complex cases
1149 are handled in noce_try_cmove_arith after noce_try_store_flag_arith
1150 has had a go at it. */
1153 noce_try_cmove (struct noce_if_info
*if_info
)
1158 if ((CONSTANT_P (if_info
->a
) || register_operand (if_info
->a
, VOIDmode
))
1159 && (CONSTANT_P (if_info
->b
) || register_operand (if_info
->b
, VOIDmode
)))
1163 code
= GET_CODE (if_info
->cond
);
1164 target
= noce_emit_cmove (if_info
, if_info
->x
, code
,
1165 XEXP (if_info
->cond
, 0),
1166 XEXP (if_info
->cond
, 1),
1167 if_info
->a
, if_info
->b
);
1171 if (target
!= if_info
->x
)
1172 noce_emit_move_insn (if_info
->x
, target
);
1174 seq
= end_ifcvt_sequence (if_info
);
1178 emit_insn_before_setloc (seq
, if_info
->jump
,
1179 INSN_LOCATOR (if_info
->insn_a
));
1192 /* Try more complex cases involving conditional_move. */
1195 noce_try_cmove_arith (struct noce_if_info
*if_info
)
1207 /* A conditional move from two memory sources is equivalent to a
1208 conditional on their addresses followed by a load. Don't do this
1209 early because it'll screw alias analysis. Note that we've
1210 already checked for no side effects. */
1211 if (! no_new_pseudos
&& cse_not_expected
1212 && MEM_P (a
) && MEM_P (b
)
1213 && BRANCH_COST
>= 5)
1217 x
= gen_reg_rtx (Pmode
);
1221 /* ??? We could handle this if we knew that a load from A or B could
1222 not fault. This is also true if we've already loaded
1223 from the address along the path from ENTRY. */
1224 else if (may_trap_p (a
) || may_trap_p (b
))
1227 /* if (test) x = a + b; else x = c - d;
1234 code
= GET_CODE (if_info
->cond
);
1235 insn_a
= if_info
->insn_a
;
1236 insn_b
= if_info
->insn_b
;
1238 /* Total insn_rtx_cost should be smaller than branch cost. Exit
1239 if insn_rtx_cost can't be estimated. */
1242 insn_cost
= insn_rtx_cost (PATTERN (insn_a
));
1243 if (insn_cost
== 0 || insn_cost
> COSTS_N_INSNS (BRANCH_COST
))
1252 insn_cost
+= insn_rtx_cost (PATTERN (insn_b
));
1253 if (insn_cost
== 0 || insn_cost
> COSTS_N_INSNS (BRANCH_COST
))
1257 /* Possibly rearrange operands to make things come out more natural. */
1258 if (reversed_comparison_code (if_info
->cond
, if_info
->jump
) != UNKNOWN
)
1261 if (rtx_equal_p (b
, x
))
1263 else if (general_operand (b
, GET_MODE (b
)))
1268 code
= reversed_comparison_code (if_info
->cond
, if_info
->jump
);
1269 tmp
= a
, a
= b
, b
= tmp
;
1270 tmp
= insn_a
, insn_a
= insn_b
, insn_b
= tmp
;
1279 /* If either operand is complex, load it into a register first.
1280 The best way to do this is to copy the original insn. In this
1281 way we preserve any clobbers etc that the insn may have had.
1282 This is of course not possible in the IS_MEM case. */
1283 if (! general_operand (a
, GET_MODE (a
)))
1288 goto end_seq_and_fail
;
1292 tmp
= gen_reg_rtx (GET_MODE (a
));
1293 tmp
= emit_insn (gen_rtx_SET (VOIDmode
, tmp
, a
));
1296 goto end_seq_and_fail
;
1299 a
= gen_reg_rtx (GET_MODE (a
));
1300 tmp
= copy_rtx (insn_a
);
1301 set
= single_set (tmp
);
1303 tmp
= emit_insn (PATTERN (tmp
));
1305 if (recog_memoized (tmp
) < 0)
1306 goto end_seq_and_fail
;
1308 if (! general_operand (b
, GET_MODE (b
)))
1313 goto end_seq_and_fail
;
1317 tmp
= gen_reg_rtx (GET_MODE (b
));
1318 tmp
= gen_rtx_SET (VOIDmode
, tmp
, b
);
1321 goto end_seq_and_fail
;
1324 b
= gen_reg_rtx (GET_MODE (b
));
1325 tmp
= copy_rtx (insn_b
);
1326 set
= single_set (tmp
);
1328 tmp
= PATTERN (tmp
);
1331 /* If insn to set up A clobbers any registers B depends on, try to
1332 swap insn that sets up A with the one that sets up B. If even
1333 that doesn't help, punt. */
1334 last
= get_last_insn ();
1335 if (last
&& modified_in_p (orig_b
, last
))
1337 tmp
= emit_insn_before (tmp
, get_insns ());
1338 if (modified_in_p (orig_a
, tmp
))
1339 goto end_seq_and_fail
;
1342 tmp
= emit_insn (tmp
);
1344 if (recog_memoized (tmp
) < 0)
1345 goto end_seq_and_fail
;
1348 target
= noce_emit_cmove (if_info
, x
, code
, XEXP (if_info
->cond
, 0),
1349 XEXP (if_info
->cond
, 1), a
, b
);
1352 goto end_seq_and_fail
;
1354 /* If we're handling a memory for above, emit the load now. */
1357 tmp
= gen_rtx_MEM (GET_MODE (if_info
->x
), target
);
1359 /* Copy over flags as appropriate. */
1360 if (MEM_VOLATILE_P (if_info
->a
) || MEM_VOLATILE_P (if_info
->b
))
1361 MEM_VOLATILE_P (tmp
) = 1;
1362 if (MEM_IN_STRUCT_P (if_info
->a
) && MEM_IN_STRUCT_P (if_info
->b
))
1363 MEM_IN_STRUCT_P (tmp
) = 1;
1364 if (MEM_SCALAR_P (if_info
->a
) && MEM_SCALAR_P (if_info
->b
))
1365 MEM_SCALAR_P (tmp
) = 1;
1366 if (MEM_ALIAS_SET (if_info
->a
) == MEM_ALIAS_SET (if_info
->b
))
1367 set_mem_alias_set (tmp
, MEM_ALIAS_SET (if_info
->a
));
1369 MIN (MEM_ALIGN (if_info
->a
), MEM_ALIGN (if_info
->b
)));
1371 noce_emit_move_insn (if_info
->x
, tmp
);
1373 else if (target
!= x
)
1374 noce_emit_move_insn (x
, target
);
1376 tmp
= end_ifcvt_sequence (if_info
);
1380 emit_insn_before_setloc (tmp
, if_info
->jump
, INSN_LOCATOR (if_info
->insn_a
));
1388 /* For most cases, the simplified condition we found is the best
1389 choice, but this is not the case for the min/max/abs transforms.
1390 For these we wish to know that it is A or B in the condition. */
1393 noce_get_alt_condition (struct noce_if_info
*if_info
, rtx target
,
1396 rtx cond
, set
, insn
;
1399 /* If target is already mentioned in the known condition, return it. */
1400 if (reg_mentioned_p (target
, if_info
->cond
))
1402 *earliest
= if_info
->cond_earliest
;
1403 return if_info
->cond
;
1406 set
= pc_set (if_info
->jump
);
1407 cond
= XEXP (SET_SRC (set
), 0);
1409 = GET_CODE (XEXP (SET_SRC (set
), 2)) == LABEL_REF
1410 && XEXP (XEXP (SET_SRC (set
), 2), 0) == JUMP_LABEL (if_info
->jump
);
1412 /* If we're looking for a constant, try to make the conditional
1413 have that constant in it. There are two reasons why it may
1414 not have the constant we want:
1416 1. GCC may have needed to put the constant in a register, because
1417 the target can't compare directly against that constant. For
1418 this case, we look for a SET immediately before the comparison
1419 that puts a constant in that register.
1421 2. GCC may have canonicalized the conditional, for example
1422 replacing "if x < 4" with "if x <= 3". We can undo that (or
1423 make equivalent types of changes) to get the constants we need
1424 if they're off by one in the right direction. */
1426 if (GET_CODE (target
) == CONST_INT
)
1428 enum rtx_code code
= GET_CODE (if_info
->cond
);
1429 rtx op_a
= XEXP (if_info
->cond
, 0);
1430 rtx op_b
= XEXP (if_info
->cond
, 1);
1433 /* First, look to see if we put a constant in a register. */
1434 prev_insn
= PREV_INSN (if_info
->cond_earliest
);
1436 && INSN_P (prev_insn
)
1437 && GET_CODE (PATTERN (prev_insn
)) == SET
)
1439 rtx src
= find_reg_equal_equiv_note (prev_insn
);
1441 src
= SET_SRC (PATTERN (prev_insn
));
1442 if (GET_CODE (src
) == CONST_INT
)
1444 if (rtx_equal_p (op_a
, SET_DEST (PATTERN (prev_insn
))))
1446 else if (rtx_equal_p (op_b
, SET_DEST (PATTERN (prev_insn
))))
1449 if (GET_CODE (op_a
) == CONST_INT
)
1454 code
= swap_condition (code
);
1459 /* Now, look to see if we can get the right constant by
1460 adjusting the conditional. */
1461 if (GET_CODE (op_b
) == CONST_INT
)
1463 HOST_WIDE_INT desired_val
= INTVAL (target
);
1464 HOST_WIDE_INT actual_val
= INTVAL (op_b
);
1469 if (actual_val
== desired_val
+ 1)
1472 op_b
= GEN_INT (desired_val
);
1476 if (actual_val
== desired_val
- 1)
1479 op_b
= GEN_INT (desired_val
);
1483 if (actual_val
== desired_val
- 1)
1486 op_b
= GEN_INT (desired_val
);
1490 if (actual_val
== desired_val
+ 1)
1493 op_b
= GEN_INT (desired_val
);
1501 /* If we made any changes, generate a new conditional that is
1502 equivalent to what we started with, but has the right
1504 if (code
!= GET_CODE (if_info
->cond
)
1505 || op_a
!= XEXP (if_info
->cond
, 0)
1506 || op_b
!= XEXP (if_info
->cond
, 1))
1508 cond
= gen_rtx_fmt_ee (code
, GET_MODE (cond
), op_a
, op_b
);
1509 *earliest
= if_info
->cond_earliest
;
1514 cond
= canonicalize_condition (if_info
->jump
, cond
, reverse
,
1515 earliest
, target
, false, true);
1516 if (! cond
|| ! reg_mentioned_p (target
, cond
))
1519 /* We almost certainly searched back to a different place.
1520 Need to re-verify correct lifetimes. */
1522 /* X may not be mentioned in the range (cond_earliest, jump]. */
1523 for (insn
= if_info
->jump
; insn
!= *earliest
; insn
= PREV_INSN (insn
))
1524 if (INSN_P (insn
) && reg_overlap_mentioned_p (if_info
->x
, PATTERN (insn
)))
1527 /* A and B may not be modified in the range [cond_earliest, jump). */
1528 for (insn
= *earliest
; insn
!= if_info
->jump
; insn
= NEXT_INSN (insn
))
1530 && (modified_in_p (if_info
->a
, insn
)
1531 || modified_in_p (if_info
->b
, insn
)))
1537 /* Convert "if (a < b) x = a; else x = b;" to "x = min(a, b);", etc. */
1540 noce_try_minmax (struct noce_if_info
*if_info
)
1542 rtx cond
, earliest
, target
, seq
;
1543 enum rtx_code code
, op
;
1546 /* ??? Can't guarantee that expand_binop won't create pseudos. */
1550 /* ??? Reject modes with NaNs or signed zeros since we don't know how
1551 they will be resolved with an SMIN/SMAX. It wouldn't be too hard
1552 to get the target to tell us... */
1553 if (HONOR_SIGNED_ZEROS (GET_MODE (if_info
->x
))
1554 || HONOR_NANS (GET_MODE (if_info
->x
)))
1557 cond
= noce_get_alt_condition (if_info
, if_info
->a
, &earliest
);
1561 /* Verify the condition is of the form we expect, and canonicalize
1562 the comparison code. */
1563 code
= GET_CODE (cond
);
1564 if (rtx_equal_p (XEXP (cond
, 0), if_info
->a
))
1566 if (! rtx_equal_p (XEXP (cond
, 1), if_info
->b
))
1569 else if (rtx_equal_p (XEXP (cond
, 1), if_info
->a
))
1571 if (! rtx_equal_p (XEXP (cond
, 0), if_info
->b
))
1573 code
= swap_condition (code
);
1578 /* Determine what sort of operation this is. Note that the code is for
1579 a taken branch, so the code->operation mapping appears backwards. */
1612 target
= expand_simple_binop (GET_MODE (if_info
->x
), op
,
1613 if_info
->a
, if_info
->b
,
1614 if_info
->x
, unsignedp
, OPTAB_WIDEN
);
1620 if (target
!= if_info
->x
)
1621 noce_emit_move_insn (if_info
->x
, target
);
1623 seq
= end_ifcvt_sequence (if_info
);
1627 emit_insn_before_setloc (seq
, if_info
->jump
, INSN_LOCATOR (if_info
->insn_a
));
1628 if_info
->cond
= cond
;
1629 if_info
->cond_earliest
= earliest
;
1634 /* Convert "if (a < 0) x = -a; else x = a;" to "x = abs(a);", etc. */
1637 noce_try_abs (struct noce_if_info
*if_info
)
1639 rtx cond
, earliest
, target
, seq
, a
, b
, c
;
1642 /* ??? Can't guarantee that expand_binop won't create pseudos. */
1646 /* Recognize A and B as constituting an ABS or NABS. */
1649 if (GET_CODE (a
) == NEG
&& rtx_equal_p (XEXP (a
, 0), b
))
1651 else if (GET_CODE (b
) == NEG
&& rtx_equal_p (XEXP (b
, 0), a
))
1653 c
= a
; a
= b
; b
= c
;
1659 cond
= noce_get_alt_condition (if_info
, b
, &earliest
);
1663 /* Verify the condition is of the form we expect. */
1664 if (rtx_equal_p (XEXP (cond
, 0), b
))
1666 else if (rtx_equal_p (XEXP (cond
, 1), b
))
1671 /* Verify that C is zero. Search backward through the block for
1672 a REG_EQUAL note if necessary. */
1675 rtx insn
, note
= NULL
;
1676 for (insn
= earliest
;
1677 insn
!= BB_HEAD (if_info
->test_bb
);
1678 insn
= PREV_INSN (insn
))
1680 && ((note
= find_reg_note (insn
, REG_EQUAL
, c
))
1681 || (note
= find_reg_note (insn
, REG_EQUIV
, c
))))
1688 && GET_CODE (XEXP (c
, 0)) == SYMBOL_REF
1689 && CONSTANT_POOL_ADDRESS_P (XEXP (c
, 0)))
1690 c
= get_pool_constant (XEXP (c
, 0));
1692 /* Work around funny ideas get_condition has wrt canonicalization.
1693 Note that these rtx constants are known to be CONST_INT, and
1694 therefore imply integer comparisons. */
1695 if (c
== constm1_rtx
&& GET_CODE (cond
) == GT
)
1697 else if (c
== const1_rtx
&& GET_CODE (cond
) == LT
)
1699 else if (c
!= CONST0_RTX (GET_MODE (b
)))
1702 /* Determine what sort of operation this is. */
1703 switch (GET_CODE (cond
))
1722 target
= expand_abs_nojump (GET_MODE (if_info
->x
), b
, if_info
->x
, 1);
1724 /* ??? It's a quandary whether cmove would be better here, especially
1725 for integers. Perhaps combine will clean things up. */
1726 if (target
&& negate
)
1727 target
= expand_simple_unop (GET_MODE (target
), NEG
, target
, if_info
->x
, 0);
1735 if (target
!= if_info
->x
)
1736 noce_emit_move_insn (if_info
->x
, target
);
1738 seq
= end_ifcvt_sequence (if_info
);
1742 emit_insn_before_setloc (seq
, if_info
->jump
, INSN_LOCATOR (if_info
->insn_a
));
1743 if_info
->cond
= cond
;
1744 if_info
->cond_earliest
= earliest
;
1749 /* Convert "if (m < 0) x = b; else x = 0;" to "x = (m >> C) & b;". */
1752 noce_try_sign_mask (struct noce_if_info
*if_info
)
1754 rtx cond
, t
, m
, c
, seq
;
1755 enum machine_mode mode
;
1761 cond
= if_info
->cond
;
1762 code
= GET_CODE (cond
);
1767 if (if_info
->a
== const0_rtx
)
1769 if ((code
== LT
&& c
== const0_rtx
)
1770 || (code
== LE
&& c
== constm1_rtx
))
1773 else if (if_info
->b
== const0_rtx
)
1775 if ((code
== GE
&& c
== const0_rtx
)
1776 || (code
== GT
&& c
== constm1_rtx
))
1780 if (! t
|| side_effects_p (t
))
1783 /* We currently don't handle different modes. */
1784 mode
= GET_MODE (t
);
1785 if (GET_MODE (m
) != mode
)
1788 /* This is only profitable if T is cheap, or T is unconditionally
1789 executed/evaluated in the original insn sequence. */
1790 if (rtx_cost (t
, SET
) >= COSTS_N_INSNS (2)
1791 && (!if_info
->b_unconditional
1792 || t
!= if_info
->b
))
1796 /* Use emit_store_flag to generate "m < 0 ? -1 : 0" instead of expanding
1797 "(signed) m >> 31" directly. This benefits targets with specialized
1798 insns to obtain the signmask, but still uses ashr_optab otherwise. */
1799 m
= emit_store_flag (gen_reg_rtx (mode
), LT
, m
, const0_rtx
, mode
, 0, -1);
1800 t
= m
? expand_binop (mode
, and_optab
, m
, t
, NULL_RTX
, 0, OPTAB_DIRECT
)
1809 noce_emit_move_insn (if_info
->x
, t
);
1811 seq
= end_ifcvt_sequence (if_info
);
1815 emit_insn_before_setloc (seq
, if_info
->jump
, INSN_LOCATOR (if_info
->insn_a
));
1820 /* Similar to get_condition, only the resulting condition must be
1821 valid at JUMP, instead of at EARLIEST. */
1824 noce_get_condition (rtx jump
, rtx
*earliest
)
1829 if (! any_condjump_p (jump
))
1832 set
= pc_set (jump
);
1834 /* If this branches to JUMP_LABEL when the condition is false,
1835 reverse the condition. */
1836 reverse
= (GET_CODE (XEXP (SET_SRC (set
), 2)) == LABEL_REF
1837 && XEXP (XEXP (SET_SRC (set
), 2), 0) == JUMP_LABEL (jump
));
1839 /* If the condition variable is a register and is MODE_INT, accept it. */
1841 cond
= XEXP (SET_SRC (set
), 0);
1842 tmp
= XEXP (cond
, 0);
1843 if (REG_P (tmp
) && GET_MODE_CLASS (GET_MODE (tmp
)) == MODE_INT
)
1848 cond
= gen_rtx_fmt_ee (reverse_condition (GET_CODE (cond
)),
1849 GET_MODE (cond
), tmp
, XEXP (cond
, 1));
1853 /* Otherwise, fall back on canonicalize_condition to do the dirty
1854 work of manipulating MODE_CC values and COMPARE rtx codes. */
1855 return canonicalize_condition (jump
, cond
, reverse
, earliest
,
1856 NULL_RTX
, false, true);
1859 /* Return true if OP is ok for if-then-else processing. */
1862 noce_operand_ok (rtx op
)
1864 /* We special-case memories, so handle any of them with
1865 no address side effects. */
1867 return ! side_effects_p (XEXP (op
, 0));
1869 if (side_effects_p (op
))
1872 return ! may_trap_p (op
);
1875 /* Given a simple IF-THEN or IF-THEN-ELSE block, attempt to convert it
1876 without using conditional execution. Return TRUE if we were
1877 successful at converting the block. */
1880 noce_process_if_block (struct ce_if_block
* ce_info
)
1882 basic_block test_bb
= ce_info
->test_bb
; /* test block */
1883 basic_block then_bb
= ce_info
->then_bb
; /* THEN */
1884 basic_block else_bb
= ce_info
->else_bb
; /* ELSE or NULL */
1885 struct noce_if_info if_info
;
1888 rtx orig_x
, x
, a
, b
;
1891 /* We're looking for patterns of the form
1893 (1) if (...) x = a; else x = b;
1894 (2) x = b; if (...) x = a;
1895 (3) if (...) x = a; // as if with an initial x = x.
1897 The later patterns require jumps to be more expensive.
1899 ??? For future expansion, look for multiple X in such patterns. */
1901 /* If test is comprised of && or || elements, don't handle it unless it is
1902 the special case of && elements without an ELSE block. */
1903 if (ce_info
->num_multiple_test_blocks
)
1905 if (else_bb
|| ! ce_info
->and_and_p
)
1908 ce_info
->test_bb
= test_bb
= ce_info
->last_test_bb
;
1909 ce_info
->num_multiple_test_blocks
= 0;
1910 ce_info
->num_and_and_blocks
= 0;
1911 ce_info
->num_or_or_blocks
= 0;
1914 /* If this is not a standard conditional jump, we can't parse it. */
1915 jump
= BB_END (test_bb
);
1916 cond
= noce_get_condition (jump
, &if_info
.cond_earliest
);
1920 /* If the conditional jump is more than just a conditional
1921 jump, then we can not do if-conversion on this block. */
1922 if (! onlyjump_p (jump
))
1925 /* We must be comparing objects whose modes imply the size. */
1926 if (GET_MODE (XEXP (cond
, 0)) == BLKmode
)
1929 /* Look for one of the potential sets. */
1930 insn_a
= first_active_insn (then_bb
);
1932 || insn_a
!= last_active_insn (then_bb
, FALSE
)
1933 || (set_a
= single_set (insn_a
)) == NULL_RTX
)
1936 x
= SET_DEST (set_a
);
1937 a
= SET_SRC (set_a
);
1939 /* Look for the other potential set. Make sure we've got equivalent
1941 /* ??? This is overconservative. Storing to two different mems is
1942 as easy as conditionally computing the address. Storing to a
1943 single mem merely requires a scratch memory to use as one of the
1944 destination addresses; often the memory immediately below the
1945 stack pointer is available for this. */
1949 insn_b
= first_active_insn (else_bb
);
1951 || insn_b
!= last_active_insn (else_bb
, FALSE
)
1952 || (set_b
= single_set (insn_b
)) == NULL_RTX
1953 || ! rtx_equal_p (x
, SET_DEST (set_b
)))
1958 insn_b
= prev_nonnote_insn (if_info
.cond_earliest
);
1959 /* We're going to be moving the evaluation of B down from above
1960 COND_EARLIEST to JUMP. Make sure the relevant data is still
1963 || !NONJUMP_INSN_P (insn_b
)
1964 || (set_b
= single_set (insn_b
)) == NULL_RTX
1965 || ! rtx_equal_p (x
, SET_DEST (set_b
))
1966 || reg_overlap_mentioned_p (x
, SET_SRC (set_b
))
1967 || modified_between_p (SET_SRC (set_b
),
1968 PREV_INSN (if_info
.cond_earliest
), jump
)
1969 /* Likewise with X. In particular this can happen when
1970 noce_get_condition looks farther back in the instruction
1971 stream than one might expect. */
1972 || reg_overlap_mentioned_p (x
, cond
)
1973 || reg_overlap_mentioned_p (x
, a
)
1974 || modified_between_p (x
, PREV_INSN (if_info
.cond_earliest
), jump
))
1975 insn_b
= set_b
= NULL_RTX
;
1978 /* If x has side effects then only the if-then-else form is safe to
1979 convert. But even in that case we would need to restore any notes
1980 (such as REG_INC) at then end. That can be tricky if
1981 noce_emit_move_insn expands to more than one insn, so disable the
1982 optimization entirely for now if there are side effects. */
1983 if (side_effects_p (x
))
1986 b
= (set_b
? SET_SRC (set_b
) : x
);
1988 /* Only operate on register destinations, and even then avoid extending
1989 the lifetime of hard registers on small register class machines. */
1992 || (SMALL_REGISTER_CLASSES
1993 && REGNO (x
) < FIRST_PSEUDO_REGISTER
))
1995 if (no_new_pseudos
|| GET_MODE (x
) == BLKmode
)
1997 x
= gen_reg_rtx (GET_MODE (GET_CODE (x
) == STRICT_LOW_PART
1998 ? XEXP (x
, 0) : x
));
2001 /* Don't operate on sources that may trap or are volatile. */
2002 if (! noce_operand_ok (a
) || ! noce_operand_ok (b
))
2005 /* Set up the info block for our subroutines. */
2006 if_info
.test_bb
= test_bb
;
2007 if_info
.cond
= cond
;
2008 if_info
.jump
= jump
;
2009 if_info
.insn_a
= insn_a
;
2010 if_info
.insn_b
= insn_b
;
2014 if_info
.b_unconditional
= else_bb
== 0;
2016 /* Try optimizations in some approximation of a useful order. */
2017 /* ??? Should first look to see if X is live incoming at all. If it
2018 isn't, we don't need anything but an unconditional set. */
2020 /* Look and see if A and B are really the same. Avoid creating silly
2021 cmove constructs that no one will fix up later. */
2022 if (rtx_equal_p (a
, b
))
2024 /* If we have an INSN_B, we don't have to create any new rtl. Just
2025 move the instruction that we already have. If we don't have an
2026 INSN_B, that means that A == X, and we've got a noop move. In
2027 that case don't do anything and let the code below delete INSN_A. */
2028 if (insn_b
&& else_bb
)
2032 if (else_bb
&& insn_b
== BB_END (else_bb
))
2033 BB_END (else_bb
) = PREV_INSN (insn_b
);
2034 reorder_insns (insn_b
, insn_b
, PREV_INSN (jump
));
2036 /* If there was a REG_EQUAL note, delete it since it may have been
2037 true due to this insn being after a jump. */
2038 if ((note
= find_reg_note (insn_b
, REG_EQUAL
, NULL_RTX
)) != 0)
2039 remove_note (insn_b
, note
);
2043 /* If we have "x = b; if (...) x = a;", and x has side-effects, then
2044 x must be executed twice. */
2045 else if (insn_b
&& side_effects_p (orig_x
))
2052 /* Disallow the "if (...) x = a;" form (with an implicit "else x = x;")
2053 for most optimizations if writing to x may trap, i.e. it's a memory
2054 other than a static var or a stack slot. */
2057 && ! MEM_NOTRAP_P (orig_x
)
2058 && rtx_addr_can_trap_p (XEXP (orig_x
, 0)))
2060 if (HAVE_conditional_move
)
2062 if (noce_try_cmove (&if_info
))
2064 if (! HAVE_conditional_execution
2065 && noce_try_cmove_arith (&if_info
))
2071 if (noce_try_move (&if_info
))
2073 if (noce_try_store_flag (&if_info
))
2075 if (noce_try_minmax (&if_info
))
2077 if (noce_try_abs (&if_info
))
2079 if (HAVE_conditional_move
2080 && noce_try_cmove (&if_info
))
2082 if (! HAVE_conditional_execution
)
2084 if (noce_try_store_flag_constants (&if_info
))
2086 if (noce_try_addcc (&if_info
))
2088 if (noce_try_store_flag_mask (&if_info
))
2090 if (HAVE_conditional_move
2091 && noce_try_cmove_arith (&if_info
))
2093 if (noce_try_sign_mask (&if_info
))
2100 /* The original sets may now be killed. */
2101 delete_insn (insn_a
);
2103 /* Several special cases here: First, we may have reused insn_b above,
2104 in which case insn_b is now NULL. Second, we want to delete insn_b
2105 if it came from the ELSE block, because follows the now correct
2106 write that appears in the TEST block. However, if we got insn_b from
2107 the TEST block, it may in fact be loading data needed for the comparison.
2108 We'll let life_analysis remove the insn if it's really dead. */
2109 if (insn_b
&& else_bb
)
2110 delete_insn (insn_b
);
2112 /* The new insns will have been inserted immediately before the jump. We
2113 should be able to remove the jump with impunity, but the condition itself
2114 may have been modified by gcse to be shared across basic blocks. */
2117 /* If we used a temporary, fix it up now. */
2121 noce_emit_move_insn (orig_x
, x
);
2122 insn_b
= get_insns ();
2123 set_used_flags (orig_x
);
2124 unshare_all_rtl_in_chain (insn_b
);
2127 emit_insn_after_setloc (insn_b
, BB_END (test_bb
), INSN_LOCATOR (insn_a
));
2130 /* Merge the blocks! */
2131 merge_if_block (ce_info
);
2136 /* Attempt to convert an IF-THEN or IF-THEN-ELSE block into
2137 straight line code. Return true if successful. */
2140 process_if_block (struct ce_if_block
* ce_info
)
2142 if (! reload_completed
2143 && noce_process_if_block (ce_info
))
2146 if (HAVE_conditional_execution
&& reload_completed
)
2148 /* If we have && and || tests, try to first handle combining the && and
2149 || tests into the conditional code, and if that fails, go back and
2150 handle it without the && and ||, which at present handles the && case
2151 if there was no ELSE block. */
2152 if (cond_exec_process_if_block (ce_info
, TRUE
))
2155 if (ce_info
->num_multiple_test_blocks
)
2159 if (cond_exec_process_if_block (ce_info
, FALSE
))
2167 /* Merge the blocks and mark for local life update. */
2170 merge_if_block (struct ce_if_block
* ce_info
)
2172 basic_block test_bb
= ce_info
->test_bb
; /* last test block */
2173 basic_block then_bb
= ce_info
->then_bb
; /* THEN */
2174 basic_block else_bb
= ce_info
->else_bb
; /* ELSE or NULL */
2175 basic_block join_bb
= ce_info
->join_bb
; /* join block */
2176 basic_block combo_bb
;
2178 /* All block merging is done into the lower block numbers. */
2182 /* Merge any basic blocks to handle && and || subtests. Each of
2183 the blocks are on the fallthru path from the predecessor block. */
2184 if (ce_info
->num_multiple_test_blocks
> 0)
2186 basic_block bb
= test_bb
;
2187 basic_block last_test_bb
= ce_info
->last_test_bb
;
2188 basic_block fallthru
= block_fallthru (bb
);
2193 fallthru
= block_fallthru (bb
);
2194 merge_blocks (combo_bb
, bb
);
2197 while (bb
!= last_test_bb
);
2200 /* Merge TEST block into THEN block. Normally the THEN block won't have a
2201 label, but it might if there were || tests. That label's count should be
2202 zero, and it normally should be removed. */
2206 if (combo_bb
->global_live_at_end
)
2207 COPY_REG_SET (combo_bb
->global_live_at_end
,
2208 then_bb
->global_live_at_end
);
2209 merge_blocks (combo_bb
, then_bb
);
2213 /* The ELSE block, if it existed, had a label. That label count
2214 will almost always be zero, but odd things can happen when labels
2215 get their addresses taken. */
2218 merge_blocks (combo_bb
, else_bb
);
2222 /* If there was no join block reported, that means it was not adjacent
2223 to the others, and so we cannot merge them. */
2227 rtx last
= BB_END (combo_bb
);
2229 /* The outgoing edge for the current COMBO block should already
2230 be correct. Verify this. */
2231 if (EDGE_COUNT (combo_bb
->succs
) == 0)
2233 if (find_reg_note (last
, REG_NORETURN
, NULL
))
2235 else if (NONJUMP_INSN_P (last
)
2236 && GET_CODE (PATTERN (last
)) == TRAP_IF
2237 && TRAP_CONDITION (PATTERN (last
)) == const_true_rtx
)
2243 /* There should still be something at the end of the THEN or ELSE
2244 blocks taking us to our final destination. */
2245 else if (JUMP_P (last
))
2247 else if (EDGE_SUCC (combo_bb
, 0)->dest
== EXIT_BLOCK_PTR
2249 && SIBLING_CALL_P (last
))
2251 else if ((EDGE_SUCC (combo_bb
, 0)->flags
& EDGE_EH
)
2252 && can_throw_internal (last
))
2258 /* The JOIN block may have had quite a number of other predecessors too.
2259 Since we've already merged the TEST, THEN and ELSE blocks, we should
2260 have only one remaining edge from our if-then-else diamond. If there
2261 is more than one remaining edge, it must come from elsewhere. There
2262 may be zero incoming edges if the THEN block didn't actually join
2263 back up (as with a call to abort). */
2264 else if (EDGE_COUNT (join_bb
->preds
) < 2
2265 && join_bb
!= EXIT_BLOCK_PTR
)
2267 /* We can merge the JOIN. */
2268 if (combo_bb
->global_live_at_end
)
2269 COPY_REG_SET (combo_bb
->global_live_at_end
,
2270 join_bb
->global_live_at_end
);
2272 merge_blocks (combo_bb
, join_bb
);
2277 /* We cannot merge the JOIN. */
2279 /* The outgoing edge for the current COMBO block should already
2280 be correct. Verify this. */
2281 gcc_assert (single_succ_p (combo_bb
)
2282 && single_succ (combo_bb
) == join_bb
);
2284 /* Remove the jump and cruft from the end of the COMBO block. */
2285 if (join_bb
!= EXIT_BLOCK_PTR
)
2286 tidy_fallthru_edge (single_succ_edge (combo_bb
));
2289 num_updated_if_blocks
++;
2292 /* Find a block ending in a simple IF condition and try to transform it
2293 in some way. When converting a multi-block condition, put the new code
2294 in the first such block and delete the rest. Return a pointer to this
2295 first block if some transformation was done. Return NULL otherwise. */
2298 find_if_header (basic_block test_bb
, int pass
)
2300 ce_if_block_t ce_info
;
2304 /* The kind of block we're looking for has exactly two successors. */
2305 if (EDGE_COUNT (test_bb
->succs
) != 2)
2308 then_edge
= EDGE_SUCC (test_bb
, 0);
2309 else_edge
= EDGE_SUCC (test_bb
, 1);
2311 /* Neither edge should be abnormal. */
2312 if ((then_edge
->flags
& EDGE_COMPLEX
)
2313 || (else_edge
->flags
& EDGE_COMPLEX
))
2316 /* Nor exit the loop. */
2317 if ((then_edge
->flags
& EDGE_LOOP_EXIT
)
2318 || (else_edge
->flags
& EDGE_LOOP_EXIT
))
2321 /* The THEN edge is canonically the one that falls through. */
2322 if (then_edge
->flags
& EDGE_FALLTHRU
)
2324 else if (else_edge
->flags
& EDGE_FALLTHRU
)
2327 else_edge
= then_edge
;
2331 /* Otherwise this must be a multiway branch of some sort. */
2334 memset (&ce_info
, '\0', sizeof (ce_info
));
2335 ce_info
.test_bb
= test_bb
;
2336 ce_info
.then_bb
= then_edge
->dest
;
2337 ce_info
.else_bb
= else_edge
->dest
;
2338 ce_info
.pass
= pass
;
2340 #ifdef IFCVT_INIT_EXTRA_FIELDS
2341 IFCVT_INIT_EXTRA_FIELDS (&ce_info
);
2344 if (find_if_block (&ce_info
))
2347 if (HAVE_trap
&& HAVE_conditional_trap
2348 && find_cond_trap (test_bb
, then_edge
, else_edge
))
2351 if (dom_computed
[CDI_POST_DOMINATORS
] >= DOM_NO_FAST_QUERY
2352 && (! HAVE_conditional_execution
|| reload_completed
))
2354 if (find_if_case_1 (test_bb
, then_edge
, else_edge
))
2356 if (find_if_case_2 (test_bb
, then_edge
, else_edge
))
2364 fprintf (dump_file
, "Conversion succeeded on pass %d.\n", pass
);
2365 return ce_info
.test_bb
;
2368 /* Return true if a block has two edges, one of which falls through to the next
2369 block, and the other jumps to a specific block, so that we can tell if the
2370 block is part of an && test or an || test. Returns either -1 or the number
2371 of non-note, non-jump, non-USE/CLOBBER insns in the block. */
2374 block_jumps_and_fallthru_p (basic_block cur_bb
, basic_block target_bb
)
2377 int fallthru_p
= FALSE
;
2384 if (!cur_bb
|| !target_bb
)
2387 /* If no edges, obviously it doesn't jump or fallthru. */
2388 if (EDGE_COUNT (cur_bb
->succs
) == 0)
2391 FOR_EACH_EDGE (cur_edge
, ei
, cur_bb
->succs
)
2393 if (cur_edge
->flags
& EDGE_COMPLEX
)
2394 /* Anything complex isn't what we want. */
2397 else if (cur_edge
->flags
& EDGE_FALLTHRU
)
2400 else if (cur_edge
->dest
== target_bb
)
2407 if ((jump_p
& fallthru_p
) == 0)
2410 /* Don't allow calls in the block, since this is used to group && and ||
2411 together for conditional execution support. ??? we should support
2412 conditional execution support across calls for IA-64 some day, but
2413 for now it makes the code simpler. */
2414 end
= BB_END (cur_bb
);
2415 insn
= BB_HEAD (cur_bb
);
2417 while (insn
!= NULL_RTX
)
2424 && GET_CODE (PATTERN (insn
)) != USE
2425 && GET_CODE (PATTERN (insn
)) != CLOBBER
)
2431 insn
= NEXT_INSN (insn
);
2437 /* Determine if a given basic block heads a simple IF-THEN or IF-THEN-ELSE
2438 block. If so, we'll try to convert the insns to not require the branch.
2439 Return TRUE if we were successful at converting the block. */
2442 find_if_block (struct ce_if_block
* ce_info
)
2444 basic_block test_bb
= ce_info
->test_bb
;
2445 basic_block then_bb
= ce_info
->then_bb
;
2446 basic_block else_bb
= ce_info
->else_bb
;
2447 basic_block join_bb
= NULL_BLOCK
;
2452 ce_info
->last_test_bb
= test_bb
;
2454 /* Discover if any fall through predecessors of the current test basic block
2455 were && tests (which jump to the else block) or || tests (which jump to
2457 if (HAVE_conditional_execution
&& reload_completed
2458 && single_pred_p (test_bb
)
2459 && single_pred_edge (test_bb
)->flags
== EDGE_FALLTHRU
)
2461 basic_block bb
= single_pred (test_bb
);
2462 basic_block target_bb
;
2463 int max_insns
= MAX_CONDITIONAL_EXECUTE
;
2466 /* Determine if the preceding block is an && or || block. */
2467 if ((n_insns
= block_jumps_and_fallthru_p (bb
, else_bb
)) >= 0)
2469 ce_info
->and_and_p
= TRUE
;
2470 target_bb
= else_bb
;
2472 else if ((n_insns
= block_jumps_and_fallthru_p (bb
, then_bb
)) >= 0)
2474 ce_info
->and_and_p
= FALSE
;
2475 target_bb
= then_bb
;
2478 target_bb
= NULL_BLOCK
;
2480 if (target_bb
&& n_insns
<= max_insns
)
2482 int total_insns
= 0;
2485 ce_info
->last_test_bb
= test_bb
;
2487 /* Found at least one && or || block, look for more. */
2490 ce_info
->test_bb
= test_bb
= bb
;
2491 total_insns
+= n_insns
;
2494 if (!single_pred_p (bb
))
2497 bb
= single_pred (bb
);
2498 n_insns
= block_jumps_and_fallthru_p (bb
, target_bb
);
2500 while (n_insns
>= 0 && (total_insns
+ n_insns
) <= max_insns
);
2502 ce_info
->num_multiple_test_blocks
= blocks
;
2503 ce_info
->num_multiple_test_insns
= total_insns
;
2505 if (ce_info
->and_and_p
)
2506 ce_info
->num_and_and_blocks
= blocks
;
2508 ce_info
->num_or_or_blocks
= blocks
;
2512 /* The THEN block of an IF-THEN combo must have exactly one predecessor,
2513 other than any || blocks which jump to the THEN block. */
2514 if ((EDGE_COUNT (then_bb
->preds
) - ce_info
->num_or_or_blocks
) != 1)
2517 /* The edges of the THEN and ELSE blocks cannot have complex edges. */
2518 FOR_EACH_EDGE (cur_edge
, ei
, then_bb
->preds
)
2520 if (cur_edge
->flags
& EDGE_COMPLEX
)
2524 FOR_EACH_EDGE (cur_edge
, ei
, else_bb
->preds
)
2526 if (cur_edge
->flags
& EDGE_COMPLEX
)
2530 /* The THEN block of an IF-THEN combo must have zero or one successors. */
2531 if (EDGE_COUNT (then_bb
->succs
) > 0
2532 && (!single_succ_p (then_bb
)
2533 || (single_succ_edge (then_bb
)->flags
& EDGE_COMPLEX
)
2534 || (flow2_completed
&& tablejump_p (BB_END (then_bb
), NULL
, NULL
))))
2537 /* If the THEN block has no successors, conditional execution can still
2538 make a conditional call. Don't do this unless the ELSE block has
2539 only one incoming edge -- the CFG manipulation is too ugly otherwise.
2540 Check for the last insn of the THEN block being an indirect jump, which
2541 is listed as not having any successors, but confuses the rest of the CE
2542 code processing. ??? we should fix this in the future. */
2543 if (EDGE_COUNT (then_bb
->succs
) == 0)
2545 if (single_pred_p (else_bb
))
2547 rtx last_insn
= BB_END (then_bb
);
2550 && NOTE_P (last_insn
)
2551 && last_insn
!= BB_HEAD (then_bb
))
2552 last_insn
= PREV_INSN (last_insn
);
2555 && JUMP_P (last_insn
)
2556 && ! simplejump_p (last_insn
))
2560 else_bb
= NULL_BLOCK
;
2566 /* If the THEN block's successor is the other edge out of the TEST block,
2567 then we have an IF-THEN combo without an ELSE. */
2568 else if (single_succ (then_bb
) == else_bb
)
2571 else_bb
= NULL_BLOCK
;
2574 /* If the THEN and ELSE block meet in a subsequent block, and the ELSE
2575 has exactly one predecessor and one successor, and the outgoing edge
2576 is not complex, then we have an IF-THEN-ELSE combo. */
2577 else if (single_succ_p (else_bb
)
2578 && single_succ (then_bb
) == single_succ (else_bb
)
2579 && single_pred_p (else_bb
)
2580 && ! (single_succ_edge (else_bb
)->flags
& EDGE_COMPLEX
)
2581 && ! (flow2_completed
&& tablejump_p (BB_END (else_bb
), NULL
, NULL
)))
2582 join_bb
= single_succ (else_bb
);
2584 /* Otherwise it is not an IF-THEN or IF-THEN-ELSE combination. */
2588 num_possible_if_blocks
++;
2593 "\nIF-THEN%s block found, pass %d, start block %d "
2594 "[insn %d], then %d [%d]",
2595 (else_bb
) ? "-ELSE" : "",
2598 BB_HEAD (test_bb
) ? (int)INSN_UID (BB_HEAD (test_bb
)) : -1,
2600 BB_HEAD (then_bb
) ? (int)INSN_UID (BB_HEAD (then_bb
)) : -1);
2603 fprintf (dump_file
, ", else %d [%d]",
2605 BB_HEAD (else_bb
) ? (int)INSN_UID (BB_HEAD (else_bb
)) : -1);
2607 fprintf (dump_file
, ", join %d [%d]",
2609 BB_HEAD (join_bb
) ? (int)INSN_UID (BB_HEAD (join_bb
)) : -1);
2611 if (ce_info
->num_multiple_test_blocks
> 0)
2612 fprintf (dump_file
, ", %d %s block%s last test %d [%d]",
2613 ce_info
->num_multiple_test_blocks
,
2614 (ce_info
->and_and_p
) ? "&&" : "||",
2615 (ce_info
->num_multiple_test_blocks
== 1) ? "" : "s",
2616 ce_info
->last_test_bb
->index
,
2617 ((BB_HEAD (ce_info
->last_test_bb
))
2618 ? (int)INSN_UID (BB_HEAD (ce_info
->last_test_bb
))
2621 fputc ('\n', dump_file
);
2624 /* Make sure IF, THEN, and ELSE, blocks are adjacent. Actually, we get the
2625 first condition for free, since we've already asserted that there's a
2626 fallthru edge from IF to THEN. Likewise for the && and || blocks, since
2627 we checked the FALLTHRU flag, those are already adjacent to the last IF
2629 /* ??? As an enhancement, move the ELSE block. Have to deal with
2630 BLOCK notes, if by no other means than aborting the merge if they
2631 exist. Sticky enough I don't want to think about it now. */
2633 if (else_bb
&& (next
= next
->next_bb
) != else_bb
)
2635 if ((next
= next
->next_bb
) != join_bb
&& join_bb
!= EXIT_BLOCK_PTR
)
2643 /* Do the real work. */
2644 ce_info
->else_bb
= else_bb
;
2645 ce_info
->join_bb
= join_bb
;
2647 return process_if_block (ce_info
);
2650 /* Convert a branch over a trap, or a branch
2651 to a trap, into a conditional trap. */
2654 find_cond_trap (basic_block test_bb
, edge then_edge
, edge else_edge
)
2656 basic_block then_bb
= then_edge
->dest
;
2657 basic_block else_bb
= else_edge
->dest
;
2658 basic_block other_bb
, trap_bb
;
2659 rtx trap
, jump
, cond
, cond_earliest
, seq
;
2662 /* Locate the block with the trap instruction. */
2663 /* ??? While we look for no successors, we really ought to allow
2664 EH successors. Need to fix merge_if_block for that to work. */
2665 if ((trap
= block_has_only_trap (then_bb
)) != NULL
)
2666 trap_bb
= then_bb
, other_bb
= else_bb
;
2667 else if ((trap
= block_has_only_trap (else_bb
)) != NULL
)
2668 trap_bb
= else_bb
, other_bb
= then_bb
;
2674 fprintf (dump_file
, "\nTRAP-IF block found, start %d, trap %d\n",
2675 test_bb
->index
, trap_bb
->index
);
2678 /* If this is not a standard conditional jump, we can't parse it. */
2679 jump
= BB_END (test_bb
);
2680 cond
= noce_get_condition (jump
, &cond_earliest
);
2684 /* If the conditional jump is more than just a conditional jump, then
2685 we can not do if-conversion on this block. */
2686 if (! onlyjump_p (jump
))
2689 /* We must be comparing objects whose modes imply the size. */
2690 if (GET_MODE (XEXP (cond
, 0)) == BLKmode
)
2693 /* Reverse the comparison code, if necessary. */
2694 code
= GET_CODE (cond
);
2695 if (then_bb
== trap_bb
)
2697 code
= reversed_comparison_code (cond
, jump
);
2698 if (code
== UNKNOWN
)
2702 /* Attempt to generate the conditional trap. */
2703 seq
= gen_cond_trap (code
, XEXP (cond
, 0),
2705 TRAP_CODE (PATTERN (trap
)));
2711 /* Emit the new insns before cond_earliest. */
2712 emit_insn_before_setloc (seq
, cond_earliest
, INSN_LOCATOR (trap
));
2714 /* Delete the trap block if possible. */
2715 remove_edge (trap_bb
== then_bb
? then_edge
: else_edge
);
2716 if (EDGE_COUNT (trap_bb
->preds
) == 0)
2717 delete_basic_block (trap_bb
);
2719 /* If the non-trap block and the test are now adjacent, merge them.
2720 Otherwise we must insert a direct branch. */
2721 if (test_bb
->next_bb
== other_bb
)
2723 struct ce_if_block new_ce_info
;
2725 memset (&new_ce_info
, '\0', sizeof (new_ce_info
));
2726 new_ce_info
.test_bb
= test_bb
;
2727 new_ce_info
.then_bb
= NULL
;
2728 new_ce_info
.else_bb
= NULL
;
2729 new_ce_info
.join_bb
= other_bb
;
2730 merge_if_block (&new_ce_info
);
2736 lab
= JUMP_LABEL (jump
);
2737 newjump
= emit_jump_insn_after (gen_jump (lab
), jump
);
2738 LABEL_NUSES (lab
) += 1;
2739 JUMP_LABEL (newjump
) = lab
;
2740 emit_barrier_after (newjump
);
2748 /* Subroutine of find_cond_trap: if BB contains only a trap insn,
2752 block_has_only_trap (basic_block bb
)
2756 /* We're not the exit block. */
2757 if (bb
== EXIT_BLOCK_PTR
)
2760 /* The block must have no successors. */
2761 if (EDGE_COUNT (bb
->succs
) > 0)
2764 /* The only instruction in the THEN block must be the trap. */
2765 trap
= first_active_insn (bb
);
2766 if (! (trap
== BB_END (bb
)
2767 && GET_CODE (PATTERN (trap
)) == TRAP_IF
2768 && TRAP_CONDITION (PATTERN (trap
)) == const_true_rtx
))
2774 /* Look for IF-THEN-ELSE cases in which one of THEN or ELSE is
2775 transformable, but not necessarily the other. There need be no
2778 Return TRUE if we were successful at converting the block.
2780 Cases we'd like to look at:
2783 if (test) goto over; // x not live
2791 if (! test) goto label;
2794 if (test) goto E; // x not live
2808 (3) // This one's really only interesting for targets that can do
2809 // multiway branching, e.g. IA-64 BBB bundles. For other targets
2810 // it results in multiple branches on a cache line, which often
2811 // does not sit well with predictors.
2813 if (test1) goto E; // predicted not taken
2829 (A) Don't do (2) if the branch is predicted against the block we're
2830 eliminating. Do it anyway if we can eliminate a branch; this requires
2831 that the sole successor of the eliminated block postdominate the other
2834 (B) With CE, on (3) we can steal from both sides of the if, creating
2843 Again, this is most useful if J postdominates.
2845 (C) CE substitutes for helpful life information.
2847 (D) These heuristics need a lot of work. */
2849 /* Tests for case 1 above. */
2852 find_if_case_1 (basic_block test_bb
, edge then_edge
, edge else_edge
)
2854 basic_block then_bb
= then_edge
->dest
;
2855 basic_block else_bb
= else_edge
->dest
, new_bb
;
2858 /* If we are partitioning hot/cold basic blocks, we don't want to
2859 mess up unconditional or indirect jumps that cross between hot
2862 Basic block partitioning may result in some jumps that appear to
2863 be optimizable (or blocks that appear to be mergeable), but which really
2864 must be left untouched (they are required to make it safely across
2865 partition boundaries). See the comments at the top of
2866 bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */
2868 if ((BB_END (then_bb
)
2869 && find_reg_note (BB_END (then_bb
), REG_CROSSING_JUMP
, NULL_RTX
))
2870 || (BB_END (test_bb
)
2871 && find_reg_note (BB_END (test_bb
), REG_CROSSING_JUMP
, NULL_RTX
))
2872 || (BB_END (else_bb
)
2873 && find_reg_note (BB_END (else_bb
), REG_CROSSING_JUMP
,
2877 /* THEN has one successor. */
2878 if (!single_succ_p (then_bb
))
2881 /* THEN does not fall through, but is not strange either. */
2882 if (single_succ_edge (then_bb
)->flags
& (EDGE_COMPLEX
| EDGE_FALLTHRU
))
2885 /* THEN has one predecessor. */
2886 if (!single_pred_p (then_bb
))
2889 /* THEN must do something. */
2890 if (forwarder_block_p (then_bb
))
2893 num_possible_if_blocks
++;
2896 "\nIF-CASE-1 found, start %d, then %d\n",
2897 test_bb
->index
, then_bb
->index
);
2899 /* THEN is small. */
2900 if (! cheap_bb_rtx_cost_p (then_bb
, COSTS_N_INSNS (BRANCH_COST
)))
2903 /* Registers set are dead, or are predicable. */
2904 if (! dead_or_predicable (test_bb
, then_bb
, else_bb
,
2905 single_succ (then_bb
), 1))
2908 /* Conversion went ok, including moving the insns and fixing up the
2909 jump. Adjust the CFG to match. */
2911 bitmap_ior (test_bb
->global_live_at_end
,
2912 else_bb
->global_live_at_start
,
2913 then_bb
->global_live_at_end
);
2916 /* We can avoid creating a new basic block if then_bb is immediately
2917 followed by else_bb, i.e. deleting then_bb allows test_bb to fall
2920 if (then_bb
->next_bb
== else_bb
2921 && then_bb
->prev_bb
== test_bb
2922 && else_bb
!= EXIT_BLOCK_PTR
)
2924 redirect_edge_succ (FALLTHRU_EDGE (test_bb
), else_bb
);
2928 new_bb
= redirect_edge_and_branch_force (FALLTHRU_EDGE (test_bb
),
2931 then_bb_index
= then_bb
->index
;
2932 delete_basic_block (then_bb
);
2934 /* Make rest of code believe that the newly created block is the THEN_BB
2935 block we removed. */
2938 new_bb
->index
= then_bb_index
;
2939 BASIC_BLOCK (then_bb_index
) = new_bb
;
2940 /* Since the fallthru edge was redirected from test_bb to new_bb,
2941 we need to ensure that new_bb is in the same partition as
2942 test bb (you can not fall through across section boundaries). */
2943 BB_COPY_PARTITION (new_bb
, test_bb
);
2945 /* We've possibly created jump to next insn, cleanup_cfg will solve that
2949 num_updated_if_blocks
++;
2954 /* Test for case 2 above. */
2957 find_if_case_2 (basic_block test_bb
, edge then_edge
, edge else_edge
)
2959 basic_block then_bb
= then_edge
->dest
;
2960 basic_block else_bb
= else_edge
->dest
;
2964 /* If we are partitioning hot/cold basic blocks, we don't want to
2965 mess up unconditional or indirect jumps that cross between hot
2968 Basic block partitioning may result in some jumps that appear to
2969 be optimizable (or blocks that appear to be mergeable), but which really
2970 must be left untouched (they are required to make it safely across
2971 partition boundaries). See the comments at the top of
2972 bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */
2974 if ((BB_END (then_bb
)
2975 && find_reg_note (BB_END (then_bb
), REG_CROSSING_JUMP
, NULL_RTX
))
2976 || (BB_END (test_bb
)
2977 && find_reg_note (BB_END (test_bb
), REG_CROSSING_JUMP
, NULL_RTX
))
2978 || (BB_END (else_bb
)
2979 && find_reg_note (BB_END (else_bb
), REG_CROSSING_JUMP
,
2983 /* ELSE has one successor. */
2984 if (!single_succ_p (else_bb
))
2987 else_succ
= single_succ_edge (else_bb
);
2989 /* ELSE outgoing edge is not complex. */
2990 if (else_succ
->flags
& EDGE_COMPLEX
)
2993 /* ELSE has one predecessor. */
2994 if (!single_pred_p (else_bb
))
2997 /* THEN is not EXIT. */
2998 if (then_bb
->index
< 0)
3001 /* ELSE is predicted or SUCC(ELSE) postdominates THEN. */
3002 note
= find_reg_note (BB_END (test_bb
), REG_BR_PROB
, NULL_RTX
);
3003 if (note
&& INTVAL (XEXP (note
, 0)) >= REG_BR_PROB_BASE
/ 2)
3005 else if (else_succ
->dest
->index
< 0
3006 || dominated_by_p (CDI_POST_DOMINATORS
, then_bb
,
3012 num_possible_if_blocks
++;
3015 "\nIF-CASE-2 found, start %d, else %d\n",
3016 test_bb
->index
, else_bb
->index
);
3018 /* ELSE is small. */
3019 if (! cheap_bb_rtx_cost_p (else_bb
, COSTS_N_INSNS (BRANCH_COST
)))
3022 /* Registers set are dead, or are predicable. */
3023 if (! dead_or_predicable (test_bb
, else_bb
, then_bb
, else_succ
->dest
, 0))
3026 /* Conversion went ok, including moving the insns and fixing up the
3027 jump. Adjust the CFG to match. */
3029 bitmap_ior (test_bb
->global_live_at_end
,
3030 then_bb
->global_live_at_start
,
3031 else_bb
->global_live_at_end
);
3033 delete_basic_block (else_bb
);
3036 num_updated_if_blocks
++;
3038 /* ??? We may now fallthru from one of THEN's successors into a join
3039 block. Rerun cleanup_cfg? Examine things manually? Wait? */
3044 /* A subroutine of dead_or_predicable called through for_each_rtx.
3045 Return 1 if a memory is found. */
3048 find_memory (rtx
*px
, void *data ATTRIBUTE_UNUSED
)
3053 /* Used by the code above to perform the actual rtl transformations.
3054 Return TRUE if successful.
3056 TEST_BB is the block containing the conditional branch. MERGE_BB
3057 is the block containing the code to manipulate. NEW_DEST is the
3058 label TEST_BB should be branching to after the conversion.
3059 REVERSEP is true if the sense of the branch should be reversed. */
3062 dead_or_predicable (basic_block test_bb
, basic_block merge_bb
,
3063 basic_block other_bb
, basic_block new_dest
, int reversep
)
3065 rtx head
, end
, jump
, earliest
= NULL_RTX
, old_dest
, new_label
= NULL_RTX
;
3067 jump
= BB_END (test_bb
);
3069 /* Find the extent of the real code in the merge block. */
3070 head
= BB_HEAD (merge_bb
);
3071 end
= BB_END (merge_bb
);
3074 head
= NEXT_INSN (head
);
3079 head
= end
= NULL_RTX
;
3082 head
= NEXT_INSN (head
);
3089 head
= end
= NULL_RTX
;
3092 end
= PREV_INSN (end
);
3095 /* Disable handling dead code by conditional execution if the machine needs
3096 to do anything funny with the tests, etc. */
3097 #ifndef IFCVT_MODIFY_TESTS
3098 if (HAVE_conditional_execution
)
3100 /* In the conditional execution case, we have things easy. We know
3101 the condition is reversible. We don't have to check life info
3102 because we're going to conditionally execute the code anyway.
3103 All that's left is making sure the insns involved can actually
3108 cond
= cond_exec_get_condition (jump
);
3112 prob_val
= find_reg_note (jump
, REG_BR_PROB
, NULL_RTX
);
3114 prob_val
= XEXP (prob_val
, 0);
3118 enum rtx_code rev
= reversed_comparison_code (cond
, jump
);
3121 cond
= gen_rtx_fmt_ee (rev
, GET_MODE (cond
), XEXP (cond
, 0),
3124 prob_val
= GEN_INT (REG_BR_PROB_BASE
- INTVAL (prob_val
));
3127 if (! cond_exec_process_insns ((ce_if_block_t
*)0, head
, end
, cond
,
3136 /* In the non-conditional execution case, we have to verify that there
3137 are no trapping operations, no calls, no references to memory, and
3138 that any registers modified are dead at the branch site. */
3140 rtx insn
, cond
, prev
;
3141 regset merge_set
, tmp
, test_live
, test_set
;
3142 struct propagate_block_info
*pbi
;
3143 unsigned i
, fail
= 0;
3146 /* Check for no calls or trapping operations. */
3147 for (insn
= head
; ; insn
= NEXT_INSN (insn
))
3153 if (may_trap_p (PATTERN (insn
)))
3156 /* ??? Even non-trapping memories such as stack frame
3157 references must be avoided. For stores, we collect
3158 no lifetime info; for reads, we'd have to assert
3159 true_dependence false against every store in the
3161 if (for_each_rtx (&PATTERN (insn
), find_memory
, NULL
))
3168 if (! any_condjump_p (jump
))
3171 /* Find the extent of the conditional. */
3172 cond
= noce_get_condition (jump
, &earliest
);
3177 MERGE_SET = set of registers set in MERGE_BB
3178 TEST_LIVE = set of registers live at EARLIEST
3179 TEST_SET = set of registers set between EARLIEST and the
3180 end of the block. */
3182 tmp
= ALLOC_REG_SET (®_obstack
);
3183 merge_set
= ALLOC_REG_SET (®_obstack
);
3184 test_live
= ALLOC_REG_SET (®_obstack
);
3185 test_set
= ALLOC_REG_SET (®_obstack
);
3187 /* ??? bb->local_set is only valid during calculate_global_regs_live,
3188 so we must recompute usage for MERGE_BB. Not so bad, I suppose,
3189 since we've already asserted that MERGE_BB is small. */
3190 propagate_block (merge_bb
, tmp
, merge_set
, merge_set
, 0);
3192 /* For small register class machines, don't lengthen lifetimes of
3193 hard registers before reload. */
3194 if (SMALL_REGISTER_CLASSES
&& ! reload_completed
)
3196 EXECUTE_IF_SET_IN_BITMAP (merge_set
, 0, i
, bi
)
3198 if (i
< FIRST_PSEUDO_REGISTER
3200 && ! global_regs
[i
])
3205 /* For TEST, we're interested in a range of insns, not a whole block.
3206 Moreover, we're interested in the insns live from OTHER_BB. */
3208 COPY_REG_SET (test_live
, other_bb
->global_live_at_start
);
3209 pbi
= init_propagate_block_info (test_bb
, test_live
, test_set
, test_set
,
3212 for (insn
= jump
; ; insn
= prev
)
3214 prev
= propagate_one_insn (pbi
, insn
);
3215 if (insn
== earliest
)
3219 free_propagate_block_info (pbi
);
3221 /* We can perform the transformation if
3222 MERGE_SET & (TEST_SET | TEST_LIVE)
3224 TEST_SET & merge_bb->global_live_at_start
3227 if (bitmap_intersect_p (test_set
, merge_set
)
3228 || bitmap_intersect_p (test_live
, merge_set
)
3229 || bitmap_intersect_p (test_set
, merge_bb
->global_live_at_start
))
3233 FREE_REG_SET (merge_set
);
3234 FREE_REG_SET (test_live
);
3235 FREE_REG_SET (test_set
);
3242 /* We don't want to use normal invert_jump or redirect_jump because
3243 we don't want to delete_insn called. Also, we want to do our own
3244 change group management. */
3246 old_dest
= JUMP_LABEL (jump
);
3247 if (other_bb
!= new_dest
)
3249 new_label
= block_label (new_dest
);
3251 ? ! invert_jump_1 (jump
, new_label
)
3252 : ! redirect_jump_1 (jump
, new_label
))
3256 if (! apply_change_group ())
3259 if (other_bb
!= new_dest
)
3261 redirect_jump_2 (jump
, old_dest
, new_label
, -1, reversep
);
3263 redirect_edge_succ (BRANCH_EDGE (test_bb
), new_dest
);
3266 gcov_type count
, probability
;
3267 count
= BRANCH_EDGE (test_bb
)->count
;
3268 BRANCH_EDGE (test_bb
)->count
= FALLTHRU_EDGE (test_bb
)->count
;
3269 FALLTHRU_EDGE (test_bb
)->count
= count
;
3270 probability
= BRANCH_EDGE (test_bb
)->probability
;
3271 BRANCH_EDGE (test_bb
)->probability
3272 = FALLTHRU_EDGE (test_bb
)->probability
;
3273 FALLTHRU_EDGE (test_bb
)->probability
= probability
;
3274 update_br_prob_note (test_bb
);
3278 /* Move the insns out of MERGE_BB to before the branch. */
3281 if (end
== BB_END (merge_bb
))
3282 BB_END (merge_bb
) = PREV_INSN (head
);
3284 if (squeeze_notes (&head
, &end
))
3287 reorder_insns (head
, end
, PREV_INSN (earliest
));
3290 /* Remove the jump and edge if we can. */
3291 if (other_bb
== new_dest
)
3294 remove_edge (BRANCH_EDGE (test_bb
));
3295 /* ??? Can't merge blocks here, as then_bb is still in use.
3296 At minimum, the merge will get done just before bb-reorder. */
3306 /* Main entry point for all if-conversion. */
3309 if_convert (int x_life_data_ok
)
3314 num_possible_if_blocks
= 0;
3315 num_updated_if_blocks
= 0;
3316 num_true_changes
= 0;
3317 life_data_ok
= (x_life_data_ok
!= 0);
3319 if ((! targetm
.cannot_modify_jumps_p ())
3320 && (!flag_reorder_blocks_and_partition
|| !no_new_pseudos
3321 || !targetm
.have_named_sections
))
3325 flow_loops_find (&loops
);
3326 mark_loop_exit_edges (&loops
);
3327 flow_loops_free (&loops
);
3328 free_dominance_info (CDI_DOMINATORS
);
3331 /* Compute postdominators if we think we'll use them. */
3332 if (HAVE_conditional_execution
|| life_data_ok
)
3333 calculate_dominance_info (CDI_POST_DOMINATORS
);
3338 /* Go through each of the basic blocks looking for things to convert. If we
3339 have conditional execution, we make multiple passes to allow us to handle
3340 IF-THEN{-ELSE} blocks within other IF-THEN{-ELSE} blocks. */
3344 cond_exec_changed_p
= FALSE
;
3347 #ifdef IFCVT_MULTIPLE_DUMPS
3348 if (dump_file
&& pass
> 1)
3349 fprintf (dump_file
, "\n\n========== Pass %d ==========\n", pass
);
3355 while ((new_bb
= find_if_header (bb
, pass
)))
3359 #ifdef IFCVT_MULTIPLE_DUMPS
3360 if (dump_file
&& cond_exec_changed_p
)
3361 print_rtl_with_bb (dump_file
, get_insns ());
3364 while (cond_exec_changed_p
);
3366 #ifdef IFCVT_MULTIPLE_DUMPS
3368 fprintf (dump_file
, "\n\n========== no more changes\n");
3371 free_dominance_info (CDI_POST_DOMINATORS
);
3376 clear_aux_for_blocks ();
3378 /* Rebuild life info for basic blocks that require it. */
3379 if (num_true_changes
&& life_data_ok
)
3381 /* If we allocated new pseudos, we must resize the array for sched1. */
3382 if (max_regno
< max_reg_num ())
3384 max_regno
= max_reg_num ();
3385 allocate_reg_info (max_regno
, FALSE
, FALSE
);
3387 update_life_info_in_dirty_blocks (UPDATE_LIFE_GLOBAL_RM_NOTES
,
3388 PROP_DEATH_NOTES
| PROP_SCAN_DEAD_CODE
3389 | PROP_KILL_DEAD_CODE
);
3392 /* Write the final stats. */
3393 if (dump_file
&& num_possible_if_blocks
> 0)
3396 "\n%d possible IF blocks searched.\n",
3397 num_possible_if_blocks
);
3399 "%d IF blocks converted.\n",
3400 num_updated_if_blocks
);
3402 "%d true changes made.\n\n\n",
3406 #ifdef ENABLE_CHECKING
3407 verify_flow_info ();