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
, inmode
;
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 inmode
= GET_MODE (inner
);
700 bitpos
= SUBREG_BYTE (outer
) * BITS_PER_UNIT
;
701 store_bit_field (inner
, GET_MODE_BITSIZE (outmode
), bitpos
, outmode
, y
);
704 /* Return sequence of instructions generated by if conversion. This
705 function calls end_sequence() to end the current stream, ensures
706 that are instructions are unshared, recognizable non-jump insns.
707 On failure, this function returns a NULL_RTX. */
710 end_ifcvt_sequence (struct noce_if_info
*if_info
)
713 rtx seq
= get_insns ();
715 set_used_flags (if_info
->x
);
716 set_used_flags (if_info
->cond
);
717 unshare_all_rtl_in_chain (seq
);
720 /* Make sure that all of the instructions emitted are recognizable,
721 and that we haven't introduced a new jump instruction.
722 As an exercise for the reader, build a general mechanism that
723 allows proper placement of required clobbers. */
724 for (insn
= seq
; insn
; insn
= NEXT_INSN (insn
))
726 || recog_memoized (insn
) == -1)
732 /* Convert "if (a != b) x = a; else x = b" into "x = a" and
733 "if (a == b) x = a; else x = b" into "x = b". */
736 noce_try_move (struct noce_if_info
*if_info
)
738 rtx cond
= if_info
->cond
;
739 enum rtx_code code
= GET_CODE (cond
);
742 if (code
!= NE
&& code
!= EQ
)
745 /* This optimization isn't valid if either A or B could be a NaN
747 if (HONOR_NANS (GET_MODE (if_info
->x
))
748 || HONOR_SIGNED_ZEROS (GET_MODE (if_info
->x
)))
751 /* Check whether the operands of the comparison are A and in
753 if ((rtx_equal_p (if_info
->a
, XEXP (cond
, 0))
754 && rtx_equal_p (if_info
->b
, XEXP (cond
, 1)))
755 || (rtx_equal_p (if_info
->a
, XEXP (cond
, 1))
756 && rtx_equal_p (if_info
->b
, XEXP (cond
, 0))))
758 y
= (code
== EQ
) ? if_info
->a
: if_info
->b
;
760 /* Avoid generating the move if the source is the destination. */
761 if (! rtx_equal_p (if_info
->x
, y
))
764 noce_emit_move_insn (if_info
->x
, y
);
765 seq
= end_ifcvt_sequence (if_info
);
769 emit_insn_before_setloc (seq
, if_info
->jump
,
770 INSN_LOCATOR (if_info
->insn_a
));
777 /* Convert "if (test) x = 1; else x = 0".
779 Only try 0 and STORE_FLAG_VALUE here. Other combinations will be
780 tried in noce_try_store_flag_constants after noce_try_cmove has had
781 a go at the conversion. */
784 noce_try_store_flag (struct noce_if_info
*if_info
)
789 if (GET_CODE (if_info
->b
) == CONST_INT
790 && INTVAL (if_info
->b
) == STORE_FLAG_VALUE
791 && if_info
->a
== const0_rtx
)
793 else if (if_info
->b
== const0_rtx
794 && GET_CODE (if_info
->a
) == CONST_INT
795 && INTVAL (if_info
->a
) == STORE_FLAG_VALUE
796 && (reversed_comparison_code (if_info
->cond
, if_info
->jump
)
804 target
= noce_emit_store_flag (if_info
, if_info
->x
, reversep
, 0);
807 if (target
!= if_info
->x
)
808 noce_emit_move_insn (if_info
->x
, target
);
810 seq
= end_ifcvt_sequence (if_info
);
814 emit_insn_before_setloc (seq
, if_info
->jump
,
815 INSN_LOCATOR (if_info
->insn_a
));
825 /* Convert "if (test) x = a; else x = b", for A and B constant. */
828 noce_try_store_flag_constants (struct noce_if_info
*if_info
)
832 HOST_WIDE_INT itrue
, ifalse
, diff
, tmp
;
833 int normalize
, can_reverse
;
834 enum machine_mode mode
;
837 && GET_CODE (if_info
->a
) == CONST_INT
838 && GET_CODE (if_info
->b
) == CONST_INT
)
840 mode
= GET_MODE (if_info
->x
);
841 ifalse
= INTVAL (if_info
->a
);
842 itrue
= INTVAL (if_info
->b
);
844 /* Make sure we can represent the difference between the two values. */
845 if ((itrue
- ifalse
> 0)
846 != ((ifalse
< 0) != (itrue
< 0) ? ifalse
< 0 : ifalse
< itrue
))
849 diff
= trunc_int_for_mode (itrue
- ifalse
, mode
);
851 can_reverse
= (reversed_comparison_code (if_info
->cond
, if_info
->jump
)
855 if (diff
== STORE_FLAG_VALUE
|| diff
== -STORE_FLAG_VALUE
)
857 else if (ifalse
== 0 && exact_log2 (itrue
) >= 0
858 && (STORE_FLAG_VALUE
== 1
859 || BRANCH_COST
>= 2))
861 else if (itrue
== 0 && exact_log2 (ifalse
) >= 0 && can_reverse
862 && (STORE_FLAG_VALUE
== 1 || BRANCH_COST
>= 2))
863 normalize
= 1, reversep
= 1;
865 && (STORE_FLAG_VALUE
== -1
866 || BRANCH_COST
>= 2))
868 else if (ifalse
== -1 && can_reverse
869 && (STORE_FLAG_VALUE
== -1 || BRANCH_COST
>= 2))
870 normalize
= -1, reversep
= 1;
871 else if ((BRANCH_COST
>= 2 && STORE_FLAG_VALUE
== -1)
879 tmp
= itrue
; itrue
= ifalse
; ifalse
= tmp
;
880 diff
= trunc_int_for_mode (-diff
, mode
);
884 target
= noce_emit_store_flag (if_info
, if_info
->x
, reversep
, normalize
);
891 /* if (test) x = 3; else x = 4;
892 => x = 3 + (test == 0); */
893 if (diff
== STORE_FLAG_VALUE
|| diff
== -STORE_FLAG_VALUE
)
895 target
= expand_simple_binop (mode
,
896 (diff
== STORE_FLAG_VALUE
898 GEN_INT (ifalse
), target
, if_info
->x
, 0,
902 /* if (test) x = 8; else x = 0;
903 => x = (test != 0) << 3; */
904 else if (ifalse
== 0 && (tmp
= exact_log2 (itrue
)) >= 0)
906 target
= expand_simple_binop (mode
, ASHIFT
,
907 target
, GEN_INT (tmp
), if_info
->x
, 0,
911 /* if (test) x = -1; else x = b;
912 => x = -(test != 0) | b; */
913 else if (itrue
== -1)
915 target
= expand_simple_binop (mode
, IOR
,
916 target
, GEN_INT (ifalse
), if_info
->x
, 0,
920 /* if (test) x = a; else x = b;
921 => x = (-(test != 0) & (b - a)) + a; */
924 target
= expand_simple_binop (mode
, AND
,
925 target
, GEN_INT (diff
), if_info
->x
, 0,
928 target
= expand_simple_binop (mode
, PLUS
,
929 target
, GEN_INT (ifalse
),
930 if_info
->x
, 0, OPTAB_WIDEN
);
939 if (target
!= if_info
->x
)
940 noce_emit_move_insn (if_info
->x
, target
);
942 seq
= end_ifcvt_sequence (if_info
);
946 emit_insn_before_setloc (seq
, if_info
->jump
,
947 INSN_LOCATOR (if_info
->insn_a
));
954 /* Convert "if (test) foo++" into "foo += (test != 0)", and
955 similarly for "foo--". */
958 noce_try_addcc (struct noce_if_info
*if_info
)
961 int subtract
, normalize
;
964 && GET_CODE (if_info
->a
) == PLUS
965 && rtx_equal_p (XEXP (if_info
->a
, 0), if_info
->b
)
966 && (reversed_comparison_code (if_info
->cond
, if_info
->jump
)
969 rtx cond
= if_info
->cond
;
970 enum rtx_code code
= reversed_comparison_code (cond
, if_info
->jump
);
972 /* First try to use addcc pattern. */
973 if (general_operand (XEXP (cond
, 0), VOIDmode
)
974 && general_operand (XEXP (cond
, 1), VOIDmode
))
977 target
= emit_conditional_add (if_info
->x
, code
,
982 XEXP (if_info
->a
, 1),
983 GET_MODE (if_info
->x
),
984 (code
== LTU
|| code
== GEU
985 || code
== LEU
|| code
== GTU
));
988 if (target
!= if_info
->x
)
989 noce_emit_move_insn (if_info
->x
, target
);
991 seq
= end_ifcvt_sequence (if_info
);
995 emit_insn_before_setloc (seq
, if_info
->jump
,
996 INSN_LOCATOR (if_info
->insn_a
));
1002 /* If that fails, construct conditional increment or decrement using
1004 if (BRANCH_COST
>= 2
1005 && (XEXP (if_info
->a
, 1) == const1_rtx
1006 || XEXP (if_info
->a
, 1) == constm1_rtx
))
1009 if (STORE_FLAG_VALUE
== INTVAL (XEXP (if_info
->a
, 1)))
1010 subtract
= 0, normalize
= 0;
1011 else if (-STORE_FLAG_VALUE
== INTVAL (XEXP (if_info
->a
, 1)))
1012 subtract
= 1, normalize
= 0;
1014 subtract
= 0, normalize
= INTVAL (XEXP (if_info
->a
, 1));
1017 target
= noce_emit_store_flag (if_info
,
1018 gen_reg_rtx (GET_MODE (if_info
->x
)),
1022 target
= expand_simple_binop (GET_MODE (if_info
->x
),
1023 subtract
? MINUS
: PLUS
,
1024 if_info
->b
, target
, if_info
->x
,
1028 if (target
!= if_info
->x
)
1029 noce_emit_move_insn (if_info
->x
, target
);
1031 seq
= end_ifcvt_sequence (if_info
);
1035 emit_insn_before_setloc (seq
, if_info
->jump
,
1036 INSN_LOCATOR (if_info
->insn_a
));
1046 /* Convert "if (test) x = 0;" to "x &= -(test == 0);" */
1049 noce_try_store_flag_mask (struct noce_if_info
*if_info
)
1055 if (! no_new_pseudos
1056 && (BRANCH_COST
>= 2
1057 || STORE_FLAG_VALUE
== -1)
1058 && ((if_info
->a
== const0_rtx
1059 && rtx_equal_p (if_info
->b
, if_info
->x
))
1060 || ((reversep
= (reversed_comparison_code (if_info
->cond
,
1063 && if_info
->b
== const0_rtx
1064 && rtx_equal_p (if_info
->a
, if_info
->x
))))
1067 target
= noce_emit_store_flag (if_info
,
1068 gen_reg_rtx (GET_MODE (if_info
->x
)),
1071 target
= expand_simple_binop (GET_MODE (if_info
->x
), AND
,
1073 target
, if_info
->x
, 0,
1078 if (target
!= if_info
->x
)
1079 noce_emit_move_insn (if_info
->x
, target
);
1081 seq
= end_ifcvt_sequence (if_info
);
1085 emit_insn_before_setloc (seq
, if_info
->jump
,
1086 INSN_LOCATOR (if_info
->insn_a
));
1096 /* Helper function for noce_try_cmove and noce_try_cmove_arith. */
1099 noce_emit_cmove (struct noce_if_info
*if_info
, rtx x
, enum rtx_code code
,
1100 rtx cmp_a
, rtx cmp_b
, rtx vfalse
, rtx vtrue
)
1102 /* If earliest == jump, try to build the cmove insn directly.
1103 This is helpful when combine has created some complex condition
1104 (like for alpha's cmovlbs) that we can't hope to regenerate
1105 through the normal interface. */
1107 if (if_info
->cond_earliest
== if_info
->jump
)
1111 tmp
= gen_rtx_fmt_ee (code
, GET_MODE (if_info
->cond
), cmp_a
, cmp_b
);
1112 tmp
= gen_rtx_IF_THEN_ELSE (GET_MODE (x
), tmp
, vtrue
, vfalse
);
1113 tmp
= gen_rtx_SET (VOIDmode
, x
, tmp
);
1116 tmp
= emit_insn (tmp
);
1118 if (recog_memoized (tmp
) >= 0)
1130 /* Don't even try if the comparison operands are weird. */
1131 if (! general_operand (cmp_a
, GET_MODE (cmp_a
))
1132 || ! general_operand (cmp_b
, GET_MODE (cmp_b
)))
1135 #if HAVE_conditional_move
1136 return emit_conditional_move (x
, code
, cmp_a
, cmp_b
, VOIDmode
,
1137 vtrue
, vfalse
, GET_MODE (x
),
1138 (code
== LTU
|| code
== GEU
1139 || code
== LEU
|| code
== GTU
));
1141 /* We'll never get here, as noce_process_if_block doesn't call the
1142 functions involved. Ifdef code, however, should be discouraged
1143 because it leads to typos in the code not selected. However,
1144 emit_conditional_move won't exist either. */
1149 /* Try only simple constants and registers here. More complex cases
1150 are handled in noce_try_cmove_arith after noce_try_store_flag_arith
1151 has had a go at it. */
1154 noce_try_cmove (struct noce_if_info
*if_info
)
1159 if ((CONSTANT_P (if_info
->a
) || register_operand (if_info
->a
, VOIDmode
))
1160 && (CONSTANT_P (if_info
->b
) || register_operand (if_info
->b
, VOIDmode
)))
1164 code
= GET_CODE (if_info
->cond
);
1165 target
= noce_emit_cmove (if_info
, if_info
->x
, code
,
1166 XEXP (if_info
->cond
, 0),
1167 XEXP (if_info
->cond
, 1),
1168 if_info
->a
, if_info
->b
);
1172 if (target
!= if_info
->x
)
1173 noce_emit_move_insn (if_info
->x
, target
);
1175 seq
= end_ifcvt_sequence (if_info
);
1179 emit_insn_before_setloc (seq
, if_info
->jump
,
1180 INSN_LOCATOR (if_info
->insn_a
));
1193 /* Try more complex cases involving conditional_move. */
1196 noce_try_cmove_arith (struct noce_if_info
*if_info
)
1208 /* A conditional move from two memory sources is equivalent to a
1209 conditional on their addresses followed by a load. Don't do this
1210 early because it'll screw alias analysis. Note that we've
1211 already checked for no side effects. */
1212 if (! no_new_pseudos
&& cse_not_expected
1213 && MEM_P (a
) && MEM_P (b
)
1214 && BRANCH_COST
>= 5)
1218 x
= gen_reg_rtx (Pmode
);
1222 /* ??? We could handle this if we knew that a load from A or B could
1223 not fault. This is also true if we've already loaded
1224 from the address along the path from ENTRY. */
1225 else if (may_trap_p (a
) || may_trap_p (b
))
1228 /* if (test) x = a + b; else x = c - d;
1235 code
= GET_CODE (if_info
->cond
);
1236 insn_a
= if_info
->insn_a
;
1237 insn_b
= if_info
->insn_b
;
1239 /* Total insn_rtx_cost should be smaller than branch cost. Exit
1240 if insn_rtx_cost can't be estimated. */
1243 insn_cost
= insn_rtx_cost (PATTERN (insn_a
));
1244 if (insn_cost
== 0 || insn_cost
> COSTS_N_INSNS (BRANCH_COST
))
1253 insn_cost
+= insn_rtx_cost (PATTERN (insn_b
));
1254 if (insn_cost
== 0 || insn_cost
> COSTS_N_INSNS (BRANCH_COST
))
1258 /* Possibly rearrange operands to make things come out more natural. */
1259 if (reversed_comparison_code (if_info
->cond
, if_info
->jump
) != UNKNOWN
)
1262 if (rtx_equal_p (b
, x
))
1264 else if (general_operand (b
, GET_MODE (b
)))
1269 code
= reversed_comparison_code (if_info
->cond
, if_info
->jump
);
1270 tmp
= a
, a
= b
, b
= tmp
;
1271 tmp
= insn_a
, insn_a
= insn_b
, insn_b
= tmp
;
1280 /* If either operand is complex, load it into a register first.
1281 The best way to do this is to copy the original insn. In this
1282 way we preserve any clobbers etc that the insn may have had.
1283 This is of course not possible in the IS_MEM case. */
1284 if (! general_operand (a
, GET_MODE (a
)))
1289 goto end_seq_and_fail
;
1293 tmp
= gen_reg_rtx (GET_MODE (a
));
1294 tmp
= emit_insn (gen_rtx_SET (VOIDmode
, tmp
, a
));
1297 goto end_seq_and_fail
;
1300 a
= gen_reg_rtx (GET_MODE (a
));
1301 tmp
= copy_rtx (insn_a
);
1302 set
= single_set (tmp
);
1304 tmp
= emit_insn (PATTERN (tmp
));
1306 if (recog_memoized (tmp
) < 0)
1307 goto end_seq_and_fail
;
1309 if (! general_operand (b
, GET_MODE (b
)))
1314 goto end_seq_and_fail
;
1318 tmp
= gen_reg_rtx (GET_MODE (b
));
1319 tmp
= gen_rtx_SET (VOIDmode
, tmp
, b
);
1322 goto end_seq_and_fail
;
1325 b
= gen_reg_rtx (GET_MODE (b
));
1326 tmp
= copy_rtx (insn_b
);
1327 set
= single_set (tmp
);
1329 tmp
= PATTERN (tmp
);
1332 /* If insn to set up A clobbers any registers B depends on, try to
1333 swap insn that sets up A with the one that sets up B. If even
1334 that doesn't help, punt. */
1335 last
= get_last_insn ();
1336 if (last
&& modified_in_p (orig_b
, last
))
1338 tmp
= emit_insn_before (tmp
, get_insns ());
1339 if (modified_in_p (orig_a
, tmp
))
1340 goto end_seq_and_fail
;
1343 tmp
= emit_insn (tmp
);
1345 if (recog_memoized (tmp
) < 0)
1346 goto end_seq_and_fail
;
1349 target
= noce_emit_cmove (if_info
, x
, code
, XEXP (if_info
->cond
, 0),
1350 XEXP (if_info
->cond
, 1), a
, b
);
1353 goto end_seq_and_fail
;
1355 /* If we're handling a memory for above, emit the load now. */
1358 tmp
= gen_rtx_MEM (GET_MODE (if_info
->x
), target
);
1360 /* Copy over flags as appropriate. */
1361 if (MEM_VOLATILE_P (if_info
->a
) || MEM_VOLATILE_P (if_info
->b
))
1362 MEM_VOLATILE_P (tmp
) = 1;
1363 if (MEM_IN_STRUCT_P (if_info
->a
) && MEM_IN_STRUCT_P (if_info
->b
))
1364 MEM_IN_STRUCT_P (tmp
) = 1;
1365 if (MEM_SCALAR_P (if_info
->a
) && MEM_SCALAR_P (if_info
->b
))
1366 MEM_SCALAR_P (tmp
) = 1;
1367 if (MEM_ALIAS_SET (if_info
->a
) == MEM_ALIAS_SET (if_info
->b
))
1368 set_mem_alias_set (tmp
, MEM_ALIAS_SET (if_info
->a
));
1370 MIN (MEM_ALIGN (if_info
->a
), MEM_ALIGN (if_info
->b
)));
1372 noce_emit_move_insn (if_info
->x
, tmp
);
1374 else if (target
!= x
)
1375 noce_emit_move_insn (x
, target
);
1377 tmp
= end_ifcvt_sequence (if_info
);
1381 emit_insn_before_setloc (tmp
, if_info
->jump
, INSN_LOCATOR (if_info
->insn_a
));
1389 /* For most cases, the simplified condition we found is the best
1390 choice, but this is not the case for the min/max/abs transforms.
1391 For these we wish to know that it is A or B in the condition. */
1394 noce_get_alt_condition (struct noce_if_info
*if_info
, rtx target
,
1397 rtx cond
, set
, insn
;
1400 /* If target is already mentioned in the known condition, return it. */
1401 if (reg_mentioned_p (target
, if_info
->cond
))
1403 *earliest
= if_info
->cond_earliest
;
1404 return if_info
->cond
;
1407 set
= pc_set (if_info
->jump
);
1408 cond
= XEXP (SET_SRC (set
), 0);
1410 = GET_CODE (XEXP (SET_SRC (set
), 2)) == LABEL_REF
1411 && XEXP (XEXP (SET_SRC (set
), 2), 0) == JUMP_LABEL (if_info
->jump
);
1413 /* If we're looking for a constant, try to make the conditional
1414 have that constant in it. There are two reasons why it may
1415 not have the constant we want:
1417 1. GCC may have needed to put the constant in a register, because
1418 the target can't compare directly against that constant. For
1419 this case, we look for a SET immediately before the comparison
1420 that puts a constant in that register.
1422 2. GCC may have canonicalized the conditional, for example
1423 replacing "if x < 4" with "if x <= 3". We can undo that (or
1424 make equivalent types of changes) to get the constants we need
1425 if they're off by one in the right direction. */
1427 if (GET_CODE (target
) == CONST_INT
)
1429 enum rtx_code code
= GET_CODE (if_info
->cond
);
1430 rtx op_a
= XEXP (if_info
->cond
, 0);
1431 rtx op_b
= XEXP (if_info
->cond
, 1);
1434 /* First, look to see if we put a constant in a register. */
1435 prev_insn
= PREV_INSN (if_info
->cond_earliest
);
1437 && INSN_P (prev_insn
)
1438 && GET_CODE (PATTERN (prev_insn
)) == SET
)
1440 rtx src
= find_reg_equal_equiv_note (prev_insn
);
1442 src
= SET_SRC (PATTERN (prev_insn
));
1443 if (GET_CODE (src
) == CONST_INT
)
1445 if (rtx_equal_p (op_a
, SET_DEST (PATTERN (prev_insn
))))
1447 else if (rtx_equal_p (op_b
, SET_DEST (PATTERN (prev_insn
))))
1450 if (GET_CODE (op_a
) == CONST_INT
)
1455 code
= swap_condition (code
);
1460 /* Now, look to see if we can get the right constant by
1461 adjusting the conditional. */
1462 if (GET_CODE (op_b
) == CONST_INT
)
1464 HOST_WIDE_INT desired_val
= INTVAL (target
);
1465 HOST_WIDE_INT actual_val
= INTVAL (op_b
);
1470 if (actual_val
== desired_val
+ 1)
1473 op_b
= GEN_INT (desired_val
);
1477 if (actual_val
== desired_val
- 1)
1480 op_b
= GEN_INT (desired_val
);
1484 if (actual_val
== desired_val
- 1)
1487 op_b
= GEN_INT (desired_val
);
1491 if (actual_val
== desired_val
+ 1)
1494 op_b
= GEN_INT (desired_val
);
1502 /* If we made any changes, generate a new conditional that is
1503 equivalent to what we started with, but has the right
1505 if (code
!= GET_CODE (if_info
->cond
)
1506 || op_a
!= XEXP (if_info
->cond
, 0)
1507 || op_b
!= XEXP (if_info
->cond
, 1))
1509 cond
= gen_rtx_fmt_ee (code
, GET_MODE (cond
), op_a
, op_b
);
1510 *earliest
= if_info
->cond_earliest
;
1515 cond
= canonicalize_condition (if_info
->jump
, cond
, reverse
,
1516 earliest
, target
, false, true);
1517 if (! cond
|| ! reg_mentioned_p (target
, cond
))
1520 /* We almost certainly searched back to a different place.
1521 Need to re-verify correct lifetimes. */
1523 /* X may not be mentioned in the range (cond_earliest, jump]. */
1524 for (insn
= if_info
->jump
; insn
!= *earliest
; insn
= PREV_INSN (insn
))
1525 if (INSN_P (insn
) && reg_overlap_mentioned_p (if_info
->x
, PATTERN (insn
)))
1528 /* A and B may not be modified in the range [cond_earliest, jump). */
1529 for (insn
= *earliest
; insn
!= if_info
->jump
; insn
= NEXT_INSN (insn
))
1531 && (modified_in_p (if_info
->a
, insn
)
1532 || modified_in_p (if_info
->b
, insn
)))
1538 /* Convert "if (a < b) x = a; else x = b;" to "x = min(a, b);", etc. */
1541 noce_try_minmax (struct noce_if_info
*if_info
)
1543 rtx cond
, earliest
, target
, seq
;
1544 enum rtx_code code
, op
;
1547 /* ??? Can't guarantee that expand_binop won't create pseudos. */
1551 /* ??? Reject modes with NaNs or signed zeros since we don't know how
1552 they will be resolved with an SMIN/SMAX. It wouldn't be too hard
1553 to get the target to tell us... */
1554 if (HONOR_SIGNED_ZEROS (GET_MODE (if_info
->x
))
1555 || HONOR_NANS (GET_MODE (if_info
->x
)))
1558 cond
= noce_get_alt_condition (if_info
, if_info
->a
, &earliest
);
1562 /* Verify the condition is of the form we expect, and canonicalize
1563 the comparison code. */
1564 code
= GET_CODE (cond
);
1565 if (rtx_equal_p (XEXP (cond
, 0), if_info
->a
))
1567 if (! rtx_equal_p (XEXP (cond
, 1), if_info
->b
))
1570 else if (rtx_equal_p (XEXP (cond
, 1), if_info
->a
))
1572 if (! rtx_equal_p (XEXP (cond
, 0), if_info
->b
))
1574 code
= swap_condition (code
);
1579 /* Determine what sort of operation this is. Note that the code is for
1580 a taken branch, so the code->operation mapping appears backwards. */
1613 target
= expand_simple_binop (GET_MODE (if_info
->x
), op
,
1614 if_info
->a
, if_info
->b
,
1615 if_info
->x
, unsignedp
, OPTAB_WIDEN
);
1621 if (target
!= if_info
->x
)
1622 noce_emit_move_insn (if_info
->x
, target
);
1624 seq
= end_ifcvt_sequence (if_info
);
1628 emit_insn_before_setloc (seq
, if_info
->jump
, INSN_LOCATOR (if_info
->insn_a
));
1629 if_info
->cond
= cond
;
1630 if_info
->cond_earliest
= earliest
;
1635 /* Convert "if (a < 0) x = -a; else x = a;" to "x = abs(a);", etc. */
1638 noce_try_abs (struct noce_if_info
*if_info
)
1640 rtx cond
, earliest
, target
, seq
, a
, b
, c
;
1643 /* ??? Can't guarantee that expand_binop won't create pseudos. */
1647 /* Recognize A and B as constituting an ABS or NABS. */
1650 if (GET_CODE (a
) == NEG
&& rtx_equal_p (XEXP (a
, 0), b
))
1652 else if (GET_CODE (b
) == NEG
&& rtx_equal_p (XEXP (b
, 0), a
))
1654 c
= a
; a
= b
; b
= c
;
1660 cond
= noce_get_alt_condition (if_info
, b
, &earliest
);
1664 /* Verify the condition is of the form we expect. */
1665 if (rtx_equal_p (XEXP (cond
, 0), b
))
1667 else if (rtx_equal_p (XEXP (cond
, 1), b
))
1672 /* Verify that C is zero. Search backward through the block for
1673 a REG_EQUAL note if necessary. */
1676 rtx insn
, note
= NULL
;
1677 for (insn
= earliest
;
1678 insn
!= BB_HEAD (if_info
->test_bb
);
1679 insn
= PREV_INSN (insn
))
1681 && ((note
= find_reg_note (insn
, REG_EQUAL
, c
))
1682 || (note
= find_reg_note (insn
, REG_EQUIV
, c
))))
1689 && GET_CODE (XEXP (c
, 0)) == SYMBOL_REF
1690 && CONSTANT_POOL_ADDRESS_P (XEXP (c
, 0)))
1691 c
= get_pool_constant (XEXP (c
, 0));
1693 /* Work around funny ideas get_condition has wrt canonicalization.
1694 Note that these rtx constants are known to be CONST_INT, and
1695 therefore imply integer comparisons. */
1696 if (c
== constm1_rtx
&& GET_CODE (cond
) == GT
)
1698 else if (c
== const1_rtx
&& GET_CODE (cond
) == LT
)
1700 else if (c
!= CONST0_RTX (GET_MODE (b
)))
1703 /* Determine what sort of operation this is. */
1704 switch (GET_CODE (cond
))
1723 target
= expand_abs_nojump (GET_MODE (if_info
->x
), b
, if_info
->x
, 1);
1725 /* ??? It's a quandary whether cmove would be better here, especially
1726 for integers. Perhaps combine will clean things up. */
1727 if (target
&& negate
)
1728 target
= expand_simple_unop (GET_MODE (target
), NEG
, target
, if_info
->x
, 0);
1736 if (target
!= if_info
->x
)
1737 noce_emit_move_insn (if_info
->x
, target
);
1739 seq
= end_ifcvt_sequence (if_info
);
1743 emit_insn_before_setloc (seq
, if_info
->jump
, INSN_LOCATOR (if_info
->insn_a
));
1744 if_info
->cond
= cond
;
1745 if_info
->cond_earliest
= earliest
;
1750 /* Convert "if (m < 0) x = b; else x = 0;" to "x = (m >> C) & b;". */
1753 noce_try_sign_mask (struct noce_if_info
*if_info
)
1755 rtx cond
, t
, m
, c
, seq
;
1756 enum machine_mode mode
;
1762 cond
= if_info
->cond
;
1763 code
= GET_CODE (cond
);
1768 if (if_info
->a
== const0_rtx
)
1770 if ((code
== LT
&& c
== const0_rtx
)
1771 || (code
== LE
&& c
== constm1_rtx
))
1774 else if (if_info
->b
== const0_rtx
)
1776 if ((code
== GE
&& c
== const0_rtx
)
1777 || (code
== GT
&& c
== constm1_rtx
))
1781 if (! t
|| side_effects_p (t
))
1784 /* We currently don't handle different modes. */
1785 mode
= GET_MODE (t
);
1786 if (GET_MODE (m
) != mode
)
1789 /* This is only profitable if T is cheap, or T is unconditionally
1790 executed/evaluated in the original insn sequence. */
1791 if (rtx_cost (t
, SET
) >= COSTS_N_INSNS (2)
1792 && (!if_info
->b_unconditional
1793 || t
!= if_info
->b
))
1797 /* Use emit_store_flag to generate "m < 0 ? -1 : 0" instead of expanding
1798 "(signed) m >> 31" directly. This benefits targets with specialized
1799 insns to obtain the signmask, but still uses ashr_optab otherwise. */
1800 m
= emit_store_flag (gen_reg_rtx (mode
), LT
, m
, const0_rtx
, mode
, 0, -1);
1801 t
= m
? expand_binop (mode
, and_optab
, m
, t
, NULL_RTX
, 0, OPTAB_DIRECT
)
1810 noce_emit_move_insn (if_info
->x
, t
);
1812 seq
= end_ifcvt_sequence (if_info
);
1816 emit_insn_before_setloc (seq
, if_info
->jump
, INSN_LOCATOR (if_info
->insn_a
));
1821 /* Similar to get_condition, only the resulting condition must be
1822 valid at JUMP, instead of at EARLIEST. */
1825 noce_get_condition (rtx jump
, rtx
*earliest
)
1830 if (! any_condjump_p (jump
))
1833 set
= pc_set (jump
);
1835 /* If this branches to JUMP_LABEL when the condition is false,
1836 reverse the condition. */
1837 reverse
= (GET_CODE (XEXP (SET_SRC (set
), 2)) == LABEL_REF
1838 && XEXP (XEXP (SET_SRC (set
), 2), 0) == JUMP_LABEL (jump
));
1840 /* If the condition variable is a register and is MODE_INT, accept it. */
1842 cond
= XEXP (SET_SRC (set
), 0);
1843 tmp
= XEXP (cond
, 0);
1844 if (REG_P (tmp
) && GET_MODE_CLASS (GET_MODE (tmp
)) == MODE_INT
)
1849 cond
= gen_rtx_fmt_ee (reverse_condition (GET_CODE (cond
)),
1850 GET_MODE (cond
), tmp
, XEXP (cond
, 1));
1854 /* Otherwise, fall back on canonicalize_condition to do the dirty
1855 work of manipulating MODE_CC values and COMPARE rtx codes. */
1856 return canonicalize_condition (jump
, cond
, reverse
, earliest
,
1857 NULL_RTX
, false, true);
1860 /* Return true if OP is ok for if-then-else processing. */
1863 noce_operand_ok (rtx op
)
1865 /* We special-case memories, so handle any of them with
1866 no address side effects. */
1868 return ! side_effects_p (XEXP (op
, 0));
1870 if (side_effects_p (op
))
1873 return ! may_trap_p (op
);
1876 /* Given a simple IF-THEN or IF-THEN-ELSE block, attempt to convert it
1877 without using conditional execution. Return TRUE if we were
1878 successful at converting the block. */
1881 noce_process_if_block (struct ce_if_block
* ce_info
)
1883 basic_block test_bb
= ce_info
->test_bb
; /* test block */
1884 basic_block then_bb
= ce_info
->then_bb
; /* THEN */
1885 basic_block else_bb
= ce_info
->else_bb
; /* ELSE or NULL */
1886 struct noce_if_info if_info
;
1889 rtx orig_x
, x
, a
, b
;
1892 /* We're looking for patterns of the form
1894 (1) if (...) x = a; else x = b;
1895 (2) x = b; if (...) x = a;
1896 (3) if (...) x = a; // as if with an initial x = x.
1898 The later patterns require jumps to be more expensive.
1900 ??? For future expansion, look for multiple X in such patterns. */
1902 /* If test is comprised of && or || elements, don't handle it unless it is
1903 the special case of && elements without an ELSE block. */
1904 if (ce_info
->num_multiple_test_blocks
)
1906 if (else_bb
|| ! ce_info
->and_and_p
)
1909 ce_info
->test_bb
= test_bb
= ce_info
->last_test_bb
;
1910 ce_info
->num_multiple_test_blocks
= 0;
1911 ce_info
->num_and_and_blocks
= 0;
1912 ce_info
->num_or_or_blocks
= 0;
1915 /* If this is not a standard conditional jump, we can't parse it. */
1916 jump
= BB_END (test_bb
);
1917 cond
= noce_get_condition (jump
, &if_info
.cond_earliest
);
1921 /* If the conditional jump is more than just a conditional
1922 jump, then we can not do if-conversion on this block. */
1923 if (! onlyjump_p (jump
))
1926 /* We must be comparing objects whose modes imply the size. */
1927 if (GET_MODE (XEXP (cond
, 0)) == BLKmode
)
1930 /* Look for one of the potential sets. */
1931 insn_a
= first_active_insn (then_bb
);
1933 || insn_a
!= last_active_insn (then_bb
, FALSE
)
1934 || (set_a
= single_set (insn_a
)) == NULL_RTX
)
1937 x
= SET_DEST (set_a
);
1938 a
= SET_SRC (set_a
);
1940 /* Look for the other potential set. Make sure we've got equivalent
1942 /* ??? This is overconservative. Storing to two different mems is
1943 as easy as conditionally computing the address. Storing to a
1944 single mem merely requires a scratch memory to use as one of the
1945 destination addresses; often the memory immediately below the
1946 stack pointer is available for this. */
1950 insn_b
= first_active_insn (else_bb
);
1952 || insn_b
!= last_active_insn (else_bb
, FALSE
)
1953 || (set_b
= single_set (insn_b
)) == NULL_RTX
1954 || ! rtx_equal_p (x
, SET_DEST (set_b
)))
1959 insn_b
= prev_nonnote_insn (if_info
.cond_earliest
);
1960 /* We're going to be moving the evaluation of B down from above
1961 COND_EARLIEST to JUMP. Make sure the relevant data is still
1964 || !NONJUMP_INSN_P (insn_b
)
1965 || (set_b
= single_set (insn_b
)) == NULL_RTX
1966 || ! rtx_equal_p (x
, SET_DEST (set_b
))
1967 || reg_overlap_mentioned_p (x
, SET_SRC (set_b
))
1968 || modified_between_p (SET_SRC (set_b
),
1969 PREV_INSN (if_info
.cond_earliest
), jump
)
1970 /* Likewise with X. In particular this can happen when
1971 noce_get_condition looks farther back in the instruction
1972 stream than one might expect. */
1973 || reg_overlap_mentioned_p (x
, cond
)
1974 || reg_overlap_mentioned_p (x
, a
)
1975 || modified_between_p (x
, PREV_INSN (if_info
.cond_earliest
), jump
))
1976 insn_b
= set_b
= NULL_RTX
;
1979 /* If x has side effects then only the if-then-else form is safe to
1980 convert. But even in that case we would need to restore any notes
1981 (such as REG_INC) at then end. That can be tricky if
1982 noce_emit_move_insn expands to more than one insn, so disable the
1983 optimization entirely for now if there are side effects. */
1984 if (side_effects_p (x
))
1987 b
= (set_b
? SET_SRC (set_b
) : x
);
1989 /* Only operate on register destinations, and even then avoid extending
1990 the lifetime of hard registers on small register class machines. */
1993 || (SMALL_REGISTER_CLASSES
1994 && REGNO (x
) < FIRST_PSEUDO_REGISTER
))
1996 if (no_new_pseudos
|| GET_MODE (x
) == BLKmode
)
1998 x
= gen_reg_rtx (GET_MODE (GET_CODE (x
) == STRICT_LOW_PART
1999 ? XEXP (x
, 0) : x
));
2002 /* Don't operate on sources that may trap or are volatile. */
2003 if (! noce_operand_ok (a
) || ! noce_operand_ok (b
))
2006 /* Set up the info block for our subroutines. */
2007 if_info
.test_bb
= test_bb
;
2008 if_info
.cond
= cond
;
2009 if_info
.jump
= jump
;
2010 if_info
.insn_a
= insn_a
;
2011 if_info
.insn_b
= insn_b
;
2015 if_info
.b_unconditional
= else_bb
== 0;
2017 /* Try optimizations in some approximation of a useful order. */
2018 /* ??? Should first look to see if X is live incoming at all. If it
2019 isn't, we don't need anything but an unconditional set. */
2021 /* Look and see if A and B are really the same. Avoid creating silly
2022 cmove constructs that no one will fix up later. */
2023 if (rtx_equal_p (a
, b
))
2025 /* If we have an INSN_B, we don't have to create any new rtl. Just
2026 move the instruction that we already have. If we don't have an
2027 INSN_B, that means that A == X, and we've got a noop move. In
2028 that case don't do anything and let the code below delete INSN_A. */
2029 if (insn_b
&& else_bb
)
2033 if (else_bb
&& insn_b
== BB_END (else_bb
))
2034 BB_END (else_bb
) = PREV_INSN (insn_b
);
2035 reorder_insns (insn_b
, insn_b
, PREV_INSN (jump
));
2037 /* If there was a REG_EQUAL note, delete it since it may have been
2038 true due to this insn being after a jump. */
2039 if ((note
= find_reg_note (insn_b
, REG_EQUAL
, NULL_RTX
)) != 0)
2040 remove_note (insn_b
, note
);
2044 /* If we have "x = b; if (...) x = a;", and x has side-effects, then
2045 x must be executed twice. */
2046 else if (insn_b
&& side_effects_p (orig_x
))
2053 /* Disallow the "if (...) x = a;" form (with an implicit "else x = x;")
2054 for most optimizations if writing to x may trap, i.e. it's a memory
2055 other than a static var or a stack slot. */
2058 && ! MEM_NOTRAP_P (orig_x
)
2059 && rtx_addr_can_trap_p (XEXP (orig_x
, 0)))
2061 if (HAVE_conditional_move
)
2063 if (noce_try_cmove (&if_info
))
2065 if (! HAVE_conditional_execution
2066 && noce_try_cmove_arith (&if_info
))
2072 if (noce_try_move (&if_info
))
2074 if (noce_try_store_flag (&if_info
))
2076 if (noce_try_minmax (&if_info
))
2078 if (noce_try_abs (&if_info
))
2080 if (HAVE_conditional_move
2081 && noce_try_cmove (&if_info
))
2083 if (! HAVE_conditional_execution
)
2085 if (noce_try_store_flag_constants (&if_info
))
2087 if (noce_try_addcc (&if_info
))
2089 if (noce_try_store_flag_mask (&if_info
))
2091 if (HAVE_conditional_move
2092 && noce_try_cmove_arith (&if_info
))
2094 if (noce_try_sign_mask (&if_info
))
2101 /* The original sets may now be killed. */
2102 delete_insn (insn_a
);
2104 /* Several special cases here: First, we may have reused insn_b above,
2105 in which case insn_b is now NULL. Second, we want to delete insn_b
2106 if it came from the ELSE block, because follows the now correct
2107 write that appears in the TEST block. However, if we got insn_b from
2108 the TEST block, it may in fact be loading data needed for the comparison.
2109 We'll let life_analysis remove the insn if it's really dead. */
2110 if (insn_b
&& else_bb
)
2111 delete_insn (insn_b
);
2113 /* The new insns will have been inserted immediately before the jump. We
2114 should be able to remove the jump with impunity, but the condition itself
2115 may have been modified by gcse to be shared across basic blocks. */
2118 /* If we used a temporary, fix it up now. */
2122 noce_emit_move_insn (orig_x
, x
);
2123 insn_b
= get_insns ();
2124 set_used_flags (orig_x
);
2125 unshare_all_rtl_in_chain (insn_b
);
2128 emit_insn_after_setloc (insn_b
, BB_END (test_bb
), INSN_LOCATOR (insn_a
));
2131 /* Merge the blocks! */
2132 merge_if_block (ce_info
);
2137 /* Attempt to convert an IF-THEN or IF-THEN-ELSE block into
2138 straight line code. Return true if successful. */
2141 process_if_block (struct ce_if_block
* ce_info
)
2143 if (! reload_completed
2144 && noce_process_if_block (ce_info
))
2147 if (HAVE_conditional_execution
&& reload_completed
)
2149 /* If we have && and || tests, try to first handle combining the && and
2150 || tests into the conditional code, and if that fails, go back and
2151 handle it without the && and ||, which at present handles the && case
2152 if there was no ELSE block. */
2153 if (cond_exec_process_if_block (ce_info
, TRUE
))
2156 if (ce_info
->num_multiple_test_blocks
)
2160 if (cond_exec_process_if_block (ce_info
, FALSE
))
2168 /* Merge the blocks and mark for local life update. */
2171 merge_if_block (struct ce_if_block
* ce_info
)
2173 basic_block test_bb
= ce_info
->test_bb
; /* last test block */
2174 basic_block then_bb
= ce_info
->then_bb
; /* THEN */
2175 basic_block else_bb
= ce_info
->else_bb
; /* ELSE or NULL */
2176 basic_block join_bb
= ce_info
->join_bb
; /* join block */
2177 basic_block combo_bb
;
2179 /* All block merging is done into the lower block numbers. */
2183 /* Merge any basic blocks to handle && and || subtests. Each of
2184 the blocks are on the fallthru path from the predecessor block. */
2185 if (ce_info
->num_multiple_test_blocks
> 0)
2187 basic_block bb
= test_bb
;
2188 basic_block last_test_bb
= ce_info
->last_test_bb
;
2189 basic_block fallthru
= block_fallthru (bb
);
2194 fallthru
= block_fallthru (bb
);
2195 merge_blocks (combo_bb
, bb
);
2198 while (bb
!= last_test_bb
);
2201 /* Merge TEST block into THEN block. Normally the THEN block won't have a
2202 label, but it might if there were || tests. That label's count should be
2203 zero, and it normally should be removed. */
2207 if (combo_bb
->global_live_at_end
)
2208 COPY_REG_SET (combo_bb
->global_live_at_end
,
2209 then_bb
->global_live_at_end
);
2210 merge_blocks (combo_bb
, then_bb
);
2214 /* The ELSE block, if it existed, had a label. That label count
2215 will almost always be zero, but odd things can happen when labels
2216 get their addresses taken. */
2219 merge_blocks (combo_bb
, else_bb
);
2223 /* If there was no join block reported, that means it was not adjacent
2224 to the others, and so we cannot merge them. */
2228 rtx last
= BB_END (combo_bb
);
2230 /* The outgoing edge for the current COMBO block should already
2231 be correct. Verify this. */
2232 if (EDGE_COUNT (combo_bb
->succs
) == 0)
2234 if (find_reg_note (last
, REG_NORETURN
, NULL
))
2236 else if (NONJUMP_INSN_P (last
)
2237 && GET_CODE (PATTERN (last
)) == TRAP_IF
2238 && TRAP_CONDITION (PATTERN (last
)) == const_true_rtx
)
2244 /* There should still be something at the end of the THEN or ELSE
2245 blocks taking us to our final destination. */
2246 else if (JUMP_P (last
))
2248 else if (EDGE_SUCC (combo_bb
, 0)->dest
== EXIT_BLOCK_PTR
2250 && SIBLING_CALL_P (last
))
2252 else if ((EDGE_SUCC (combo_bb
, 0)->flags
& EDGE_EH
)
2253 && can_throw_internal (last
))
2259 /* The JOIN block may have had quite a number of other predecessors too.
2260 Since we've already merged the TEST, THEN and ELSE blocks, we should
2261 have only one remaining edge from our if-then-else diamond. If there
2262 is more than one remaining edge, it must come from elsewhere. There
2263 may be zero incoming edges if the THEN block didn't actually join
2264 back up (as with a call to abort). */
2265 else if (EDGE_COUNT (join_bb
->preds
) < 2
2266 && join_bb
!= EXIT_BLOCK_PTR
)
2268 /* We can merge the JOIN. */
2269 if (combo_bb
->global_live_at_end
)
2270 COPY_REG_SET (combo_bb
->global_live_at_end
,
2271 join_bb
->global_live_at_end
);
2273 merge_blocks (combo_bb
, join_bb
);
2278 /* We cannot merge the JOIN. */
2280 /* The outgoing edge for the current COMBO block should already
2281 be correct. Verify this. */
2282 if (EDGE_COUNT (combo_bb
->succs
) > 1
2283 || EDGE_SUCC (combo_bb
, 0)->dest
!= join_bb
)
2286 /* Remove the jump and cruft from the end of the COMBO block. */
2287 if (join_bb
!= EXIT_BLOCK_PTR
)
2288 tidy_fallthru_edge (EDGE_SUCC (combo_bb
, 0));
2291 num_updated_if_blocks
++;
2294 /* Find a block ending in a simple IF condition and try to transform it
2295 in some way. When converting a multi-block condition, put the new code
2296 in the first such block and delete the rest. Return a pointer to this
2297 first block if some transformation was done. Return NULL otherwise. */
2300 find_if_header (basic_block test_bb
, int pass
)
2302 ce_if_block_t ce_info
;
2306 /* The kind of block we're looking for has exactly two successors. */
2307 if (EDGE_COUNT (test_bb
->succs
) != 2)
2310 then_edge
= EDGE_SUCC (test_bb
, 0);
2311 else_edge
= EDGE_SUCC (test_bb
, 1);
2313 /* Neither edge should be abnormal. */
2314 if ((then_edge
->flags
& EDGE_COMPLEX
)
2315 || (else_edge
->flags
& EDGE_COMPLEX
))
2318 /* Nor exit the loop. */
2319 if ((then_edge
->flags
& EDGE_LOOP_EXIT
)
2320 || (else_edge
->flags
& EDGE_LOOP_EXIT
))
2323 /* The THEN edge is canonically the one that falls through. */
2324 if (then_edge
->flags
& EDGE_FALLTHRU
)
2326 else if (else_edge
->flags
& EDGE_FALLTHRU
)
2329 else_edge
= then_edge
;
2333 /* Otherwise this must be a multiway branch of some sort. */
2336 memset (&ce_info
, '\0', sizeof (ce_info
));
2337 ce_info
.test_bb
= test_bb
;
2338 ce_info
.then_bb
= then_edge
->dest
;
2339 ce_info
.else_bb
= else_edge
->dest
;
2340 ce_info
.pass
= pass
;
2342 #ifdef IFCVT_INIT_EXTRA_FIELDS
2343 IFCVT_INIT_EXTRA_FIELDS (&ce_info
);
2346 if (find_if_block (&ce_info
))
2349 if (HAVE_trap
&& HAVE_conditional_trap
2350 && find_cond_trap (test_bb
, then_edge
, else_edge
))
2353 if (dom_computed
[CDI_POST_DOMINATORS
] >= DOM_NO_FAST_QUERY
2354 && (! HAVE_conditional_execution
|| reload_completed
))
2356 if (find_if_case_1 (test_bb
, then_edge
, else_edge
))
2358 if (find_if_case_2 (test_bb
, then_edge
, else_edge
))
2366 fprintf (dump_file
, "Conversion succeeded on pass %d.\n", pass
);
2367 return ce_info
.test_bb
;
2370 /* Return true if a block has two edges, one of which falls through to the next
2371 block, and the other jumps to a specific block, so that we can tell if the
2372 block is part of an && test or an || test. Returns either -1 or the number
2373 of non-note, non-jump, non-USE/CLOBBER insns in the block. */
2376 block_jumps_and_fallthru_p (basic_block cur_bb
, basic_block target_bb
)
2379 int fallthru_p
= FALSE
;
2386 if (!cur_bb
|| !target_bb
)
2389 /* If no edges, obviously it doesn't jump or fallthru. */
2390 if (EDGE_COUNT (cur_bb
->succs
) == 0)
2393 FOR_EACH_EDGE (cur_edge
, ei
, cur_bb
->succs
)
2395 if (cur_edge
->flags
& EDGE_COMPLEX
)
2396 /* Anything complex isn't what we want. */
2399 else if (cur_edge
->flags
& EDGE_FALLTHRU
)
2402 else if (cur_edge
->dest
== target_bb
)
2409 if ((jump_p
& fallthru_p
) == 0)
2412 /* Don't allow calls in the block, since this is used to group && and ||
2413 together for conditional execution support. ??? we should support
2414 conditional execution support across calls for IA-64 some day, but
2415 for now it makes the code simpler. */
2416 end
= BB_END (cur_bb
);
2417 insn
= BB_HEAD (cur_bb
);
2419 while (insn
!= NULL_RTX
)
2426 && GET_CODE (PATTERN (insn
)) != USE
2427 && GET_CODE (PATTERN (insn
)) != CLOBBER
)
2433 insn
= NEXT_INSN (insn
);
2439 /* Determine if a given basic block heads a simple IF-THEN or IF-THEN-ELSE
2440 block. If so, we'll try to convert the insns to not require the branch.
2441 Return TRUE if we were successful at converting the block. */
2444 find_if_block (struct ce_if_block
* ce_info
)
2446 basic_block test_bb
= ce_info
->test_bb
;
2447 basic_block then_bb
= ce_info
->then_bb
;
2448 basic_block else_bb
= ce_info
->else_bb
;
2449 basic_block join_bb
= NULL_BLOCK
;
2454 ce_info
->last_test_bb
= test_bb
;
2456 /* Discover if any fall through predecessors of the current test basic block
2457 were && tests (which jump to the else block) or || tests (which jump to
2459 if (HAVE_conditional_execution
&& reload_completed
2460 && EDGE_COUNT (test_bb
->preds
) == 1
2461 && EDGE_PRED (test_bb
, 0)->flags
== EDGE_FALLTHRU
)
2463 basic_block bb
= EDGE_PRED (test_bb
, 0)->src
;
2464 basic_block target_bb
;
2465 int max_insns
= MAX_CONDITIONAL_EXECUTE
;
2468 /* Determine if the preceding block is an && or || block. */
2469 if ((n_insns
= block_jumps_and_fallthru_p (bb
, else_bb
)) >= 0)
2471 ce_info
->and_and_p
= TRUE
;
2472 target_bb
= else_bb
;
2474 else if ((n_insns
= block_jumps_and_fallthru_p (bb
, then_bb
)) >= 0)
2476 ce_info
->and_and_p
= FALSE
;
2477 target_bb
= then_bb
;
2480 target_bb
= NULL_BLOCK
;
2482 if (target_bb
&& n_insns
<= max_insns
)
2484 int total_insns
= 0;
2487 ce_info
->last_test_bb
= test_bb
;
2489 /* Found at least one && or || block, look for more. */
2492 ce_info
->test_bb
= test_bb
= bb
;
2493 total_insns
+= n_insns
;
2496 if (EDGE_COUNT (bb
->preds
) != 1)
2499 bb
= EDGE_PRED (bb
, 0)->src
;
2500 n_insns
= block_jumps_and_fallthru_p (bb
, target_bb
);
2502 while (n_insns
>= 0 && (total_insns
+ n_insns
) <= max_insns
);
2504 ce_info
->num_multiple_test_blocks
= blocks
;
2505 ce_info
->num_multiple_test_insns
= total_insns
;
2507 if (ce_info
->and_and_p
)
2508 ce_info
->num_and_and_blocks
= blocks
;
2510 ce_info
->num_or_or_blocks
= blocks
;
2514 /* The THEN block of an IF-THEN combo must have exactly one predecessor,
2515 other than any || blocks which jump to the THEN block. */
2516 if ((EDGE_COUNT (then_bb
->preds
) - ce_info
->num_or_or_blocks
) != 1)
2519 /* The edges of the THEN and ELSE blocks cannot have complex edges. */
2520 FOR_EACH_EDGE (cur_edge
, ei
, then_bb
->preds
)
2522 if (cur_edge
->flags
& EDGE_COMPLEX
)
2526 FOR_EACH_EDGE (cur_edge
, ei
, else_bb
->preds
)
2528 if (cur_edge
->flags
& EDGE_COMPLEX
)
2532 /* The THEN block of an IF-THEN combo must have zero or one successors. */
2533 if (EDGE_COUNT (then_bb
->succs
) > 0
2534 && (EDGE_COUNT (then_bb
->succs
) > 1
2535 || (EDGE_SUCC (then_bb
, 0)->flags
& EDGE_COMPLEX
)
2536 || (flow2_completed
&& tablejump_p (BB_END (then_bb
), NULL
, NULL
))))
2539 /* If the THEN block has no successors, conditional execution can still
2540 make a conditional call. Don't do this unless the ELSE block has
2541 only one incoming edge -- the CFG manipulation is too ugly otherwise.
2542 Check for the last insn of the THEN block being an indirect jump, which
2543 is listed as not having any successors, but confuses the rest of the CE
2544 code processing. ??? we should fix this in the future. */
2545 if (EDGE_COUNT (then_bb
->succs
) == 0)
2547 if (EDGE_COUNT (else_bb
->preds
) == 1)
2549 rtx last_insn
= BB_END (then_bb
);
2552 && NOTE_P (last_insn
)
2553 && last_insn
!= BB_HEAD (then_bb
))
2554 last_insn
= PREV_INSN (last_insn
);
2557 && JUMP_P (last_insn
)
2558 && ! simplejump_p (last_insn
))
2562 else_bb
= NULL_BLOCK
;
2568 /* If the THEN block's successor is the other edge out of the TEST block,
2569 then we have an IF-THEN combo without an ELSE. */
2570 else if (EDGE_SUCC (then_bb
, 0)->dest
== else_bb
)
2573 else_bb
= NULL_BLOCK
;
2576 /* If the THEN and ELSE block meet in a subsequent block, and the ELSE
2577 has exactly one predecessor and one successor, and the outgoing edge
2578 is not complex, then we have an IF-THEN-ELSE combo. */
2579 else if (EDGE_COUNT (else_bb
->succs
) == 1
2580 && EDGE_SUCC (then_bb
, 0)->dest
== EDGE_SUCC (else_bb
, 0)->dest
2581 && EDGE_COUNT (else_bb
->preds
) == 1
2582 && ! (EDGE_SUCC (else_bb
, 0)->flags
& EDGE_COMPLEX
)
2583 && ! (flow2_completed
&& tablejump_p (BB_END (else_bb
), NULL
, NULL
)))
2584 join_bb
= EDGE_SUCC (else_bb
, 0)->dest
;
2586 /* Otherwise it is not an IF-THEN or IF-THEN-ELSE combination. */
2590 num_possible_if_blocks
++;
2595 "\nIF-THEN%s block found, pass %d, start block %d "
2596 "[insn %d], then %d [%d]",
2597 (else_bb
) ? "-ELSE" : "",
2600 BB_HEAD (test_bb
) ? (int)INSN_UID (BB_HEAD (test_bb
)) : -1,
2602 BB_HEAD (then_bb
) ? (int)INSN_UID (BB_HEAD (then_bb
)) : -1);
2605 fprintf (dump_file
, ", else %d [%d]",
2607 BB_HEAD (else_bb
) ? (int)INSN_UID (BB_HEAD (else_bb
)) : -1);
2609 fprintf (dump_file
, ", join %d [%d]",
2611 BB_HEAD (join_bb
) ? (int)INSN_UID (BB_HEAD (join_bb
)) : -1);
2613 if (ce_info
->num_multiple_test_blocks
> 0)
2614 fprintf (dump_file
, ", %d %s block%s last test %d [%d]",
2615 ce_info
->num_multiple_test_blocks
,
2616 (ce_info
->and_and_p
) ? "&&" : "||",
2617 (ce_info
->num_multiple_test_blocks
== 1) ? "" : "s",
2618 ce_info
->last_test_bb
->index
,
2619 ((BB_HEAD (ce_info
->last_test_bb
))
2620 ? (int)INSN_UID (BB_HEAD (ce_info
->last_test_bb
))
2623 fputc ('\n', dump_file
);
2626 /* Make sure IF, THEN, and ELSE, blocks are adjacent. Actually, we get the
2627 first condition for free, since we've already asserted that there's a
2628 fallthru edge from IF to THEN. Likewise for the && and || blocks, since
2629 we checked the FALLTHRU flag, those are already adjacent to the last IF
2631 /* ??? As an enhancement, move the ELSE block. Have to deal with
2632 BLOCK notes, if by no other means than aborting the merge if they
2633 exist. Sticky enough I don't want to think about it now. */
2635 if (else_bb
&& (next
= next
->next_bb
) != else_bb
)
2637 if ((next
= next
->next_bb
) != join_bb
&& join_bb
!= EXIT_BLOCK_PTR
)
2645 /* Do the real work. */
2646 ce_info
->else_bb
= else_bb
;
2647 ce_info
->join_bb
= join_bb
;
2649 return process_if_block (ce_info
);
2652 /* Convert a branch over a trap, or a branch
2653 to a trap, into a conditional trap. */
2656 find_cond_trap (basic_block test_bb
, edge then_edge
, edge else_edge
)
2658 basic_block then_bb
= then_edge
->dest
;
2659 basic_block else_bb
= else_edge
->dest
;
2660 basic_block other_bb
, trap_bb
;
2661 rtx trap
, jump
, cond
, cond_earliest
, seq
;
2664 /* Locate the block with the trap instruction. */
2665 /* ??? While we look for no successors, we really ought to allow
2666 EH successors. Need to fix merge_if_block for that to work. */
2667 if ((trap
= block_has_only_trap (then_bb
)) != NULL
)
2668 trap_bb
= then_bb
, other_bb
= else_bb
;
2669 else if ((trap
= block_has_only_trap (else_bb
)) != NULL
)
2670 trap_bb
= else_bb
, other_bb
= then_bb
;
2676 fprintf (dump_file
, "\nTRAP-IF block found, start %d, trap %d\n",
2677 test_bb
->index
, trap_bb
->index
);
2680 /* If this is not a standard conditional jump, we can't parse it. */
2681 jump
= BB_END (test_bb
);
2682 cond
= noce_get_condition (jump
, &cond_earliest
);
2686 /* If the conditional jump is more than just a conditional jump, then
2687 we can not do if-conversion on this block. */
2688 if (! onlyjump_p (jump
))
2691 /* We must be comparing objects whose modes imply the size. */
2692 if (GET_MODE (XEXP (cond
, 0)) == BLKmode
)
2695 /* Reverse the comparison code, if necessary. */
2696 code
= GET_CODE (cond
);
2697 if (then_bb
== trap_bb
)
2699 code
= reversed_comparison_code (cond
, jump
);
2700 if (code
== UNKNOWN
)
2704 /* Attempt to generate the conditional trap. */
2705 seq
= gen_cond_trap (code
, XEXP (cond
, 0),
2707 TRAP_CODE (PATTERN (trap
)));
2713 /* Emit the new insns before cond_earliest. */
2714 emit_insn_before_setloc (seq
, cond_earliest
, INSN_LOCATOR (trap
));
2716 /* Delete the trap block if possible. */
2717 remove_edge (trap_bb
== then_bb
? then_edge
: else_edge
);
2718 if (EDGE_COUNT (trap_bb
->preds
) == 0)
2719 delete_basic_block (trap_bb
);
2721 /* If the non-trap block and the test are now adjacent, merge them.
2722 Otherwise we must insert a direct branch. */
2723 if (test_bb
->next_bb
== other_bb
)
2725 struct ce_if_block new_ce_info
;
2727 memset (&new_ce_info
, '\0', sizeof (new_ce_info
));
2728 new_ce_info
.test_bb
= test_bb
;
2729 new_ce_info
.then_bb
= NULL
;
2730 new_ce_info
.else_bb
= NULL
;
2731 new_ce_info
.join_bb
= other_bb
;
2732 merge_if_block (&new_ce_info
);
2738 lab
= JUMP_LABEL (jump
);
2739 newjump
= emit_jump_insn_after (gen_jump (lab
), jump
);
2740 LABEL_NUSES (lab
) += 1;
2741 JUMP_LABEL (newjump
) = lab
;
2742 emit_barrier_after (newjump
);
2750 /* Subroutine of find_cond_trap: if BB contains only a trap insn,
2754 block_has_only_trap (basic_block bb
)
2758 /* We're not the exit block. */
2759 if (bb
== EXIT_BLOCK_PTR
)
2762 /* The block must have no successors. */
2763 if (EDGE_COUNT (bb
->succs
) > 0)
2766 /* The only instruction in the THEN block must be the trap. */
2767 trap
= first_active_insn (bb
);
2768 if (! (trap
== BB_END (bb
)
2769 && GET_CODE (PATTERN (trap
)) == TRAP_IF
2770 && TRAP_CONDITION (PATTERN (trap
)) == const_true_rtx
))
2776 /* Look for IF-THEN-ELSE cases in which one of THEN or ELSE is
2777 transformable, but not necessarily the other. There need be no
2780 Return TRUE if we were successful at converting the block.
2782 Cases we'd like to look at:
2785 if (test) goto over; // x not live
2793 if (! test) goto label;
2796 if (test) goto E; // x not live
2810 (3) // This one's really only interesting for targets that can do
2811 // multiway branching, e.g. IA-64 BBB bundles. For other targets
2812 // it results in multiple branches on a cache line, which often
2813 // does not sit well with predictors.
2815 if (test1) goto E; // predicted not taken
2831 (A) Don't do (2) if the branch is predicted against the block we're
2832 eliminating. Do it anyway if we can eliminate a branch; this requires
2833 that the sole successor of the eliminated block postdominate the other
2836 (B) With CE, on (3) we can steal from both sides of the if, creating
2845 Again, this is most useful if J postdominates.
2847 (C) CE substitutes for helpful life information.
2849 (D) These heuristics need a lot of work. */
2851 /* Tests for case 1 above. */
2854 find_if_case_1 (basic_block test_bb
, edge then_edge
, edge else_edge
)
2856 basic_block then_bb
= then_edge
->dest
;
2857 basic_block else_bb
= else_edge
->dest
, new_bb
;
2860 /* If we are partitioning hot/cold basic blocks, we don't want to
2861 mess up unconditional or indirect jumps that cross between hot
2864 Basic block partitioning may result in some jumps that appear to
2865 be optimizable (or blocks that appear to be mergeable), but which really
2866 must be left untouched (they are required to make it safely across
2867 partition boundaries). See the comments at the top of
2868 bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */
2870 if (flag_reorder_blocks_and_partition
2871 && ((BB_END (then_bb
)
2872 && find_reg_note (BB_END (then_bb
), REG_CROSSING_JUMP
, NULL_RTX
))
2873 || (BB_END (else_bb
)
2874 && find_reg_note (BB_END (else_bb
), REG_CROSSING_JUMP
,
2878 /* THEN has one successor. */
2879 if (EDGE_COUNT (then_bb
->succs
) != 1)
2882 /* THEN does not fall through, but is not strange either. */
2883 if (EDGE_SUCC (then_bb
, 0)->flags
& (EDGE_COMPLEX
| EDGE_FALLTHRU
))
2886 /* THEN has one predecessor. */
2887 if (EDGE_COUNT (then_bb
->preds
) != 1)
2890 /* THEN must do something. */
2891 if (forwarder_block_p (then_bb
))
2894 num_possible_if_blocks
++;
2897 "\nIF-CASE-1 found, start %d, then %d\n",
2898 test_bb
->index
, then_bb
->index
);
2900 /* THEN is small. */
2901 if (! cheap_bb_rtx_cost_p (then_bb
, COSTS_N_INSNS (BRANCH_COST
)))
2904 /* Registers set are dead, or are predicable. */
2905 if (! dead_or_predicable (test_bb
, then_bb
, else_bb
,
2906 EDGE_SUCC (then_bb
, 0)->dest
, 1))
2909 /* Conversion went ok, including moving the insns and fixing up the
2910 jump. Adjust the CFG to match. */
2912 bitmap_ior (test_bb
->global_live_at_end
,
2913 else_bb
->global_live_at_start
,
2914 then_bb
->global_live_at_end
);
2917 /* We can avoid creating a new basic block if then_bb is immediately
2918 followed by else_bb, i.e. deleting then_bb allows test_bb to fall
2921 if (then_bb
->next_bb
== else_bb
2922 && then_bb
->prev_bb
== test_bb
2923 && else_bb
!= EXIT_BLOCK_PTR
)
2925 redirect_edge_succ (FALLTHRU_EDGE (test_bb
), else_bb
);
2929 new_bb
= redirect_edge_and_branch_force (FALLTHRU_EDGE (test_bb
),
2932 then_bb_index
= then_bb
->index
;
2933 delete_basic_block (then_bb
);
2935 /* Make rest of code believe that the newly created block is the THEN_BB
2936 block we removed. */
2939 new_bb
->index
= then_bb_index
;
2940 BASIC_BLOCK (then_bb_index
) = new_bb
;
2941 /* Since the fallthru edge was redirected from test_bb to new_bb,
2942 we need to ensure that new_bb is in the same partition as
2943 test bb (you can not fall through across section boundaries). */
2944 BB_COPY_PARTITION (new_bb
, test_bb
);
2946 /* We've possibly created jump to next insn, cleanup_cfg will solve that
2950 num_updated_if_blocks
++;
2955 /* Test for case 2 above. */
2958 find_if_case_2 (basic_block test_bb
, edge then_edge
, edge else_edge
)
2960 basic_block then_bb
= then_edge
->dest
;
2961 basic_block else_bb
= else_edge
->dest
;
2965 /* If we are partitioning hot/cold basic blocks, we don't want to
2966 mess up unconditional or indirect jumps that cross between hot
2969 Basic block partitioning may result in some jumps that appear to
2970 be optimizable (or blocks that appear to be mergeable), but which really
2971 must be left untouched (they are required to make it safely across
2972 partition boundaries). See the comments at the top of
2973 bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */
2975 if (flag_reorder_blocks_and_partition
2976 && ((BB_END (then_bb
)
2977 && find_reg_note (BB_END (then_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 (EDGE_COUNT (else_bb
->succs
) != 1)
2987 else_succ
= EDGE_SUCC (else_bb
, 0);
2989 /* ELSE outgoing edge is not complex. */
2990 if (else_succ
->flags
& EDGE_COMPLEX
)
2993 /* ELSE has one predecessor. */
2994 if (EDGE_COUNT (else_bb
->preds
) != 1)
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 ();