1 /* If-conversion support.
2 Copyright (C) 2000, 2001, 2002, 2003, 2004, 2005, 2006
3 Free Software Foundation, Inc.
5 This file is part of GCC.
7 GCC is free software; you can redistribute it and/or modify it
8 under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 2, or (at your option)
12 GCC is distributed in the hope that it will be useful, but WITHOUT
13 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
14 or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public
15 License for more details.
17 You should have received a copy of the GNU General Public License
18 along with GCC; see the file COPYING. If not, write to the Free
19 Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA
24 #include "coretypes.h"
31 #include "insn-config.h"
34 #include "hard-reg-set.h"
35 #include "basic-block.h"
45 #include "tree-pass.h"
48 #ifndef HAVE_conditional_execution
49 #define HAVE_conditional_execution 0
51 #ifndef HAVE_conditional_move
52 #define HAVE_conditional_move 0
63 #ifndef HAVE_conditional_trap
64 #define HAVE_conditional_trap 0
67 #ifndef MAX_CONDITIONAL_EXECUTE
68 #define MAX_CONDITIONAL_EXECUTE (BRANCH_COST + 1)
71 #define NULL_BLOCK ((basic_block) NULL)
73 /* # of IF-THEN or IF-THEN-ELSE blocks we looked at */
74 static int num_possible_if_blocks
;
76 /* # of IF-THEN or IF-THEN-ELSE blocks were converted to conditional
78 static int num_updated_if_blocks
;
80 /* # of changes made which require life information to be updated. */
81 static int num_true_changes
;
83 /* Whether conditional execution changes were made. */
84 static int cond_exec_changed_p
;
86 /* True if life data ok at present. */
87 static bool life_data_ok
;
89 /* Forward references. */
90 static int count_bb_insns (basic_block
);
91 static bool cheap_bb_rtx_cost_p (basic_block
, int);
92 static rtx
first_active_insn (basic_block
);
93 static rtx
last_active_insn (basic_block
, int);
94 static basic_block
block_fallthru (basic_block
);
95 static int cond_exec_process_insns (ce_if_block_t
*, rtx
, rtx
, rtx
, rtx
, int);
96 static rtx
cond_exec_get_condition (rtx
);
97 static int cond_exec_process_if_block (ce_if_block_t
*, int);
98 static rtx
noce_get_condition (rtx
, rtx
*);
99 static int noce_operand_ok (rtx
);
100 static int noce_process_if_block (ce_if_block_t
*);
101 static int process_if_block (ce_if_block_t
*);
102 static void merge_if_block (ce_if_block_t
*);
103 static int find_cond_trap (basic_block
, edge
, edge
);
104 static basic_block
find_if_header (basic_block
, int);
105 static int block_jumps_and_fallthru_p (basic_block
, basic_block
);
106 static int find_if_block (ce_if_block_t
*);
107 static int find_if_case_1 (basic_block
, edge
, edge
);
108 static int find_if_case_2 (basic_block
, edge
, edge
);
109 static int find_memory (rtx
*, void *);
110 static int dead_or_predicable (basic_block
, basic_block
, basic_block
,
112 static void noce_emit_move_insn (rtx
, rtx
);
113 static rtx
block_has_only_trap (basic_block
);
115 /* Count the number of non-jump active insns in BB. */
118 count_bb_insns (basic_block bb
)
121 rtx insn
= BB_HEAD (bb
);
125 if (CALL_P (insn
) || NONJUMP_INSN_P (insn
))
128 if (insn
== BB_END (bb
))
130 insn
= NEXT_INSN (insn
);
136 /* Determine whether the total insn_rtx_cost on non-jump insns in
137 basic block BB is less than MAX_COST. This function returns
138 false if the cost of any instruction could not be estimated. */
141 cheap_bb_rtx_cost_p (basic_block bb
, int max_cost
)
144 rtx insn
= BB_HEAD (bb
);
148 if (NONJUMP_INSN_P (insn
))
150 int cost
= insn_rtx_cost (PATTERN (insn
));
154 /* If this instruction is the load or set of a "stack" register,
155 such as a floating point register on x87, then the cost of
156 speculatively executing this insn may need to include
157 the additional cost of popping its result off of the
158 register stack. Unfortunately, correctly recognizing and
159 accounting for this additional overhead is tricky, so for
160 now we simply prohibit such speculative execution. */
163 rtx set
= single_set (insn
);
164 if (set
&& STACK_REG_P (SET_DEST (set
)))
170 if (count
>= max_cost
)
173 else if (CALL_P (insn
))
176 if (insn
== BB_END (bb
))
178 insn
= NEXT_INSN (insn
);
184 /* Return the first non-jump active insn in the basic block. */
187 first_active_insn (basic_block bb
)
189 rtx insn
= BB_HEAD (bb
);
193 if (insn
== BB_END (bb
))
195 insn
= NEXT_INSN (insn
);
198 while (NOTE_P (insn
))
200 if (insn
== BB_END (bb
))
202 insn
= NEXT_INSN (insn
);
211 /* Return the last non-jump active (non-jump) insn in the basic block. */
214 last_active_insn (basic_block bb
, int skip_use_p
)
216 rtx insn
= BB_END (bb
);
217 rtx head
= BB_HEAD (bb
);
222 && NONJUMP_INSN_P (insn
)
223 && GET_CODE (PATTERN (insn
)) == USE
))
227 insn
= PREV_INSN (insn
);
236 /* Return the basic block reached by falling though the basic block BB. */
239 block_fallthru (basic_block bb
)
244 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
245 if (e
->flags
& EDGE_FALLTHRU
)
248 return (e
) ? e
->dest
: NULL_BLOCK
;
251 /* Go through a bunch of insns, converting them to conditional
252 execution format if possible. Return TRUE if all of the non-note
253 insns were processed. */
256 cond_exec_process_insns (ce_if_block_t
*ce_info ATTRIBUTE_UNUSED
,
257 /* if block information */rtx start
,
258 /* first insn to look at */rtx end
,
259 /* last insn to look at */rtx test
,
260 /* conditional execution test */rtx prob_val
,
261 /* probability of branch taken. */int mod_ok
)
263 int must_be_last
= FALSE
;
271 for (insn
= start
; ; insn
= NEXT_INSN (insn
))
276 gcc_assert(NONJUMP_INSN_P (insn
) || CALL_P (insn
));
278 /* Remove USE insns that get in the way. */
279 if (reload_completed
&& GET_CODE (PATTERN (insn
)) == USE
)
281 /* ??? Ug. Actually unlinking the thing is problematic,
282 given what we'd have to coordinate with our callers. */
283 SET_INSN_DELETED (insn
);
287 /* Last insn wasn't last? */
291 if (modified_in_p (test
, insn
))
298 /* Now build the conditional form of the instruction. */
299 pattern
= PATTERN (insn
);
300 xtest
= copy_rtx (test
);
302 /* If this is already a COND_EXEC, rewrite the test to be an AND of the
304 if (GET_CODE (pattern
) == COND_EXEC
)
306 if (GET_MODE (xtest
) != GET_MODE (COND_EXEC_TEST (pattern
)))
309 xtest
= gen_rtx_AND (GET_MODE (xtest
), xtest
,
310 COND_EXEC_TEST (pattern
));
311 pattern
= COND_EXEC_CODE (pattern
);
314 pattern
= gen_rtx_COND_EXEC (VOIDmode
, xtest
, pattern
);
316 /* If the machine needs to modify the insn being conditionally executed,
317 say for example to force a constant integer operand into a temp
318 register, do so here. */
319 #ifdef IFCVT_MODIFY_INSN
320 IFCVT_MODIFY_INSN (ce_info
, pattern
, insn
);
325 validate_change (insn
, &PATTERN (insn
), pattern
, 1);
327 if (CALL_P (insn
) && prob_val
)
328 validate_change (insn
, ®_NOTES (insn
),
329 alloc_EXPR_LIST (REG_BR_PROB
, prob_val
,
330 REG_NOTES (insn
)), 1);
340 /* Return the condition for a jump. Do not do any special processing. */
343 cond_exec_get_condition (rtx jump
)
347 if (any_condjump_p (jump
))
348 test_if
= SET_SRC (pc_set (jump
));
351 cond
= XEXP (test_if
, 0);
353 /* If this branches to JUMP_LABEL when the condition is false,
354 reverse the condition. */
355 if (GET_CODE (XEXP (test_if
, 2)) == LABEL_REF
356 && XEXP (XEXP (test_if
, 2), 0) == JUMP_LABEL (jump
))
358 enum rtx_code rev
= reversed_comparison_code (cond
, jump
);
362 cond
= gen_rtx_fmt_ee (rev
, GET_MODE (cond
), XEXP (cond
, 0),
369 /* Given a simple IF-THEN or IF-THEN-ELSE block, attempt to convert it
370 to conditional execution. Return TRUE if we were successful at
371 converting the block. */
374 cond_exec_process_if_block (ce_if_block_t
* ce_info
,
375 /* if block information */int do_multiple_p
)
377 basic_block test_bb
= ce_info
->test_bb
; /* last test block */
378 basic_block then_bb
= ce_info
->then_bb
; /* THEN */
379 basic_block else_bb
= ce_info
->else_bb
; /* ELSE or NULL */
380 rtx test_expr
; /* expression in IF_THEN_ELSE that is tested */
381 rtx then_start
; /* first insn in THEN block */
382 rtx then_end
; /* last insn + 1 in THEN block */
383 rtx else_start
= NULL_RTX
; /* first insn in ELSE block or NULL */
384 rtx else_end
= NULL_RTX
; /* last insn + 1 in ELSE block */
385 int max
; /* max # of insns to convert. */
386 int then_mod_ok
; /* whether conditional mods are ok in THEN */
387 rtx true_expr
; /* test for else block insns */
388 rtx false_expr
; /* test for then block insns */
389 rtx true_prob_val
; /* probability of else block */
390 rtx false_prob_val
; /* probability of then block */
392 enum rtx_code false_code
;
394 /* If test is comprised of && or || elements, and we've failed at handling
395 all of them together, just use the last test if it is the special case of
396 && elements without an ELSE block. */
397 if (!do_multiple_p
&& ce_info
->num_multiple_test_blocks
)
399 if (else_bb
|| ! ce_info
->and_and_p
)
402 ce_info
->test_bb
= test_bb
= ce_info
->last_test_bb
;
403 ce_info
->num_multiple_test_blocks
= 0;
404 ce_info
->num_and_and_blocks
= 0;
405 ce_info
->num_or_or_blocks
= 0;
408 /* Find the conditional jump to the ELSE or JOIN part, and isolate
410 test_expr
= cond_exec_get_condition (BB_END (test_bb
));
414 /* If the conditional jump is more than just a conditional jump,
415 then we can not do conditional execution conversion on this block. */
416 if (! onlyjump_p (BB_END (test_bb
)))
419 /* Collect the bounds of where we're to search, skipping any labels, jumps
420 and notes at the beginning and end of the block. Then count the total
421 number of insns and see if it is small enough to convert. */
422 then_start
= first_active_insn (then_bb
);
423 then_end
= last_active_insn (then_bb
, TRUE
);
424 n_insns
= ce_info
->num_then_insns
= count_bb_insns (then_bb
);
425 max
= MAX_CONDITIONAL_EXECUTE
;
430 else_start
= first_active_insn (else_bb
);
431 else_end
= last_active_insn (else_bb
, TRUE
);
432 n_insns
+= ce_info
->num_else_insns
= count_bb_insns (else_bb
);
438 /* Map test_expr/test_jump into the appropriate MD tests to use on
439 the conditionally executed code. */
441 true_expr
= test_expr
;
443 false_code
= reversed_comparison_code (true_expr
, BB_END (test_bb
));
444 if (false_code
!= UNKNOWN
)
445 false_expr
= gen_rtx_fmt_ee (false_code
, GET_MODE (true_expr
),
446 XEXP (true_expr
, 0), XEXP (true_expr
, 1));
448 false_expr
= NULL_RTX
;
450 #ifdef IFCVT_MODIFY_TESTS
451 /* If the machine description needs to modify the tests, such as setting a
452 conditional execution register from a comparison, it can do so here. */
453 IFCVT_MODIFY_TESTS (ce_info
, true_expr
, false_expr
);
455 /* See if the conversion failed. */
456 if (!true_expr
|| !false_expr
)
460 true_prob_val
= find_reg_note (BB_END (test_bb
), REG_BR_PROB
, NULL_RTX
);
463 true_prob_val
= XEXP (true_prob_val
, 0);
464 false_prob_val
= GEN_INT (REG_BR_PROB_BASE
- INTVAL (true_prob_val
));
467 false_prob_val
= NULL_RTX
;
469 /* If we have && or || tests, do them here. These tests are in the adjacent
470 blocks after the first block containing the test. */
471 if (ce_info
->num_multiple_test_blocks
> 0)
473 basic_block bb
= test_bb
;
474 basic_block last_test_bb
= ce_info
->last_test_bb
;
483 enum rtx_code f_code
;
485 bb
= block_fallthru (bb
);
486 start
= first_active_insn (bb
);
487 end
= last_active_insn (bb
, TRUE
);
489 && ! cond_exec_process_insns (ce_info
, start
, end
, false_expr
,
490 false_prob_val
, FALSE
))
493 /* If the conditional jump is more than just a conditional jump, then
494 we can not do conditional execution conversion on this block. */
495 if (! onlyjump_p (BB_END (bb
)))
498 /* Find the conditional jump and isolate the test. */
499 t
= cond_exec_get_condition (BB_END (bb
));
503 f_code
= reversed_comparison_code (t
, BB_END (bb
));
504 if (f_code
== UNKNOWN
)
507 f
= gen_rtx_fmt_ee (f_code
, GET_MODE (t
), XEXP (t
, 0), XEXP (t
, 1));
508 if (ce_info
->and_and_p
)
510 t
= gen_rtx_AND (GET_MODE (t
), true_expr
, t
);
511 f
= gen_rtx_IOR (GET_MODE (t
), false_expr
, f
);
515 t
= gen_rtx_IOR (GET_MODE (t
), true_expr
, t
);
516 f
= gen_rtx_AND (GET_MODE (t
), false_expr
, f
);
519 /* If the machine description needs to modify the tests, such as
520 setting a conditional execution register from a comparison, it can
522 #ifdef IFCVT_MODIFY_MULTIPLE_TESTS
523 IFCVT_MODIFY_MULTIPLE_TESTS (ce_info
, bb
, t
, f
);
525 /* See if the conversion failed. */
533 while (bb
!= last_test_bb
);
536 /* For IF-THEN-ELSE blocks, we don't allow modifications of the test
537 on then THEN block. */
538 then_mod_ok
= (else_bb
== NULL_BLOCK
);
540 /* Go through the THEN and ELSE blocks converting the insns if possible
541 to conditional execution. */
545 || ! cond_exec_process_insns (ce_info
, then_start
, then_end
,
546 false_expr
, false_prob_val
,
550 if (else_bb
&& else_end
551 && ! cond_exec_process_insns (ce_info
, else_start
, else_end
,
552 true_expr
, true_prob_val
, TRUE
))
555 /* If we cannot apply the changes, fail. Do not go through the normal fail
556 processing, since apply_change_group will call cancel_changes. */
557 if (! apply_change_group ())
559 #ifdef IFCVT_MODIFY_CANCEL
560 /* Cancel any machine dependent changes. */
561 IFCVT_MODIFY_CANCEL (ce_info
);
566 #ifdef IFCVT_MODIFY_FINAL
567 /* Do any machine dependent final modifications. */
568 IFCVT_MODIFY_FINAL (ce_info
);
571 /* Conversion succeeded. */
573 fprintf (dump_file
, "%d insn%s converted to conditional execution.\n",
574 n_insns
, (n_insns
== 1) ? " was" : "s were");
576 /* Merge the blocks! */
577 merge_if_block (ce_info
);
578 cond_exec_changed_p
= TRUE
;
582 #ifdef IFCVT_MODIFY_CANCEL
583 /* Cancel any machine dependent changes. */
584 IFCVT_MODIFY_CANCEL (ce_info
);
591 /* Used by noce_process_if_block to communicate with its subroutines.
593 The subroutines know that A and B may be evaluated freely. They
594 know that X is a register. They should insert new instructions
595 before cond_earliest. */
602 rtx jump
, cond
, cond_earliest
;
603 /* True if "b" was originally evaluated unconditionally. */
604 bool b_unconditional
;
607 static rtx
noce_emit_store_flag (struct noce_if_info
*, rtx
, int, int);
608 static int noce_try_move (struct noce_if_info
*);
609 static int noce_try_store_flag (struct noce_if_info
*);
610 static int noce_try_addcc (struct noce_if_info
*);
611 static int noce_try_store_flag_constants (struct noce_if_info
*);
612 static int noce_try_store_flag_mask (struct noce_if_info
*);
613 static rtx
noce_emit_cmove (struct noce_if_info
*, rtx
, enum rtx_code
, rtx
,
615 static int noce_try_cmove (struct noce_if_info
*);
616 static int noce_try_cmove_arith (struct noce_if_info
*);
617 static rtx
noce_get_alt_condition (struct noce_if_info
*, rtx
, rtx
*);
618 static int noce_try_minmax (struct noce_if_info
*);
619 static int noce_try_abs (struct noce_if_info
*);
620 static int noce_try_sign_mask (struct noce_if_info
*);
622 /* Helper function for noce_try_store_flag*. */
625 noce_emit_store_flag (struct noce_if_info
*if_info
, rtx x
, int reversep
,
628 rtx cond
= if_info
->cond
;
632 cond_complex
= (! general_operand (XEXP (cond
, 0), VOIDmode
)
633 || ! general_operand (XEXP (cond
, 1), VOIDmode
));
635 /* If earliest == jump, or when the condition is complex, try to
636 build the store_flag insn directly. */
639 cond
= XEXP (SET_SRC (pc_set (if_info
->jump
)), 0);
642 code
= reversed_comparison_code (cond
, if_info
->jump
);
644 code
= GET_CODE (cond
);
646 if ((if_info
->cond_earliest
== if_info
->jump
|| cond_complex
)
647 && (normalize
== 0 || STORE_FLAG_VALUE
== normalize
))
651 tmp
= gen_rtx_fmt_ee (code
, GET_MODE (x
), XEXP (cond
, 0),
653 tmp
= gen_rtx_SET (VOIDmode
, x
, tmp
);
656 tmp
= emit_insn (tmp
);
658 if (recog_memoized (tmp
) >= 0)
664 if_info
->cond_earliest
= if_info
->jump
;
672 /* Don't even try if the comparison operands or the mode of X are weird. */
673 if (cond_complex
|| !SCALAR_INT_MODE_P (GET_MODE (x
)))
676 return emit_store_flag (x
, code
, XEXP (cond
, 0),
677 XEXP (cond
, 1), VOIDmode
,
678 (code
== LTU
|| code
== LEU
679 || code
== GEU
|| code
== GTU
), normalize
);
682 /* Emit instruction to move an rtx, possibly into STRICT_LOW_PART.
683 X is the destination/target and Y is the value to copy. */
686 noce_emit_move_insn (rtx x
, rtx y
)
688 enum machine_mode outmode
;
692 if (GET_CODE (x
) != STRICT_LOW_PART
)
694 rtx seq
, insn
, target
;
698 /* Check that the SET_SRC is reasonable before calling emit_move_insn,
699 otherwise construct a suitable SET pattern ourselves. */
700 insn
= (OBJECT_P (y
) || CONSTANT_P (y
) || GET_CODE (y
) == SUBREG
)
701 ? emit_move_insn (x
, y
)
702 : emit_insn (gen_rtx_SET (VOIDmode
, x
, y
));
706 if (recog_memoized (insn
) <= 0)
708 if (GET_CODE (x
) == ZERO_EXTRACT
)
710 rtx op
= XEXP (x
, 0);
711 unsigned HOST_WIDE_INT size
= INTVAL (XEXP (x
, 1));
712 unsigned HOST_WIDE_INT start
= INTVAL (XEXP (x
, 2));
714 /* store_bit_field expects START to be relative to
715 BYTES_BIG_ENDIAN and adjusts this value for machines with
716 BITS_BIG_ENDIAN != BYTES_BIG_ENDIAN. In order to be able to
717 invoke store_bit_field again it is necessary to have the START
718 value from the first call. */
719 if (BITS_BIG_ENDIAN
!= BYTES_BIG_ENDIAN
)
722 start
= BITS_PER_UNIT
- start
- size
;
725 gcc_assert (REG_P (op
));
726 start
= BITS_PER_WORD
- start
- size
;
730 gcc_assert (start
< (MEM_P (op
) ? BITS_PER_UNIT
: BITS_PER_WORD
));
731 store_bit_field (op
, size
, start
, GET_MODE (x
), y
);
735 switch (GET_RTX_CLASS (GET_CODE (y
)))
738 ot
= code_to_optab
[GET_CODE (y
)];
742 target
= expand_unop (GET_MODE (y
), ot
, XEXP (y
, 0), x
, 0);
743 if (target
!= NULL_RTX
)
746 emit_move_insn (x
, target
);
755 ot
= code_to_optab
[GET_CODE (y
)];
759 target
= expand_binop (GET_MODE (y
), ot
,
760 XEXP (y
, 0), XEXP (y
, 1),
762 if (target
!= NULL_RTX
)
765 emit_move_insn (x
, target
);
782 inner
= XEXP (outer
, 0);
783 outmode
= GET_MODE (outer
);
784 bitpos
= SUBREG_BYTE (outer
) * BITS_PER_UNIT
;
785 store_bit_field (inner
, GET_MODE_BITSIZE (outmode
), bitpos
, outmode
, y
);
788 /* Return sequence of instructions generated by if conversion. This
789 function calls end_sequence() to end the current stream, ensures
790 that are instructions are unshared, recognizable non-jump insns.
791 On failure, this function returns a NULL_RTX. */
794 end_ifcvt_sequence (struct noce_if_info
*if_info
)
797 rtx seq
= get_insns ();
799 set_used_flags (if_info
->x
);
800 set_used_flags (if_info
->cond
);
801 unshare_all_rtl_in_chain (seq
);
804 /* Make sure that all of the instructions emitted are recognizable,
805 and that we haven't introduced a new jump instruction.
806 As an exercise for the reader, build a general mechanism that
807 allows proper placement of required clobbers. */
808 for (insn
= seq
; insn
; insn
= NEXT_INSN (insn
))
810 || recog_memoized (insn
) == -1)
816 /* Convert "if (a != b) x = a; else x = b" into "x = a" and
817 "if (a == b) x = a; else x = b" into "x = b". */
820 noce_try_move (struct noce_if_info
*if_info
)
822 rtx cond
= if_info
->cond
;
823 enum rtx_code code
= GET_CODE (cond
);
826 if (code
!= NE
&& code
!= EQ
)
829 /* This optimization isn't valid if either A or B could be a NaN
831 if (HONOR_NANS (GET_MODE (if_info
->x
))
832 || HONOR_SIGNED_ZEROS (GET_MODE (if_info
->x
)))
835 /* Check whether the operands of the comparison are A and in
837 if ((rtx_equal_p (if_info
->a
, XEXP (cond
, 0))
838 && rtx_equal_p (if_info
->b
, XEXP (cond
, 1)))
839 || (rtx_equal_p (if_info
->a
, XEXP (cond
, 1))
840 && rtx_equal_p (if_info
->b
, XEXP (cond
, 0))))
842 y
= (code
== EQ
) ? if_info
->a
: if_info
->b
;
844 /* Avoid generating the move if the source is the destination. */
845 if (! rtx_equal_p (if_info
->x
, y
))
848 noce_emit_move_insn (if_info
->x
, y
);
849 seq
= end_ifcvt_sequence (if_info
);
853 emit_insn_before_setloc (seq
, if_info
->jump
,
854 INSN_LOCATOR (if_info
->insn_a
));
861 /* Convert "if (test) x = 1; else x = 0".
863 Only try 0 and STORE_FLAG_VALUE here. Other combinations will be
864 tried in noce_try_store_flag_constants after noce_try_cmove has had
865 a go at the conversion. */
868 noce_try_store_flag (struct noce_if_info
*if_info
)
873 if (GET_CODE (if_info
->b
) == CONST_INT
874 && INTVAL (if_info
->b
) == STORE_FLAG_VALUE
875 && if_info
->a
== const0_rtx
)
877 else if (if_info
->b
== const0_rtx
878 && GET_CODE (if_info
->a
) == CONST_INT
879 && INTVAL (if_info
->a
) == STORE_FLAG_VALUE
880 && (reversed_comparison_code (if_info
->cond
, if_info
->jump
)
888 target
= noce_emit_store_flag (if_info
, if_info
->x
, reversep
, 0);
891 if (target
!= if_info
->x
)
892 noce_emit_move_insn (if_info
->x
, target
);
894 seq
= end_ifcvt_sequence (if_info
);
898 emit_insn_before_setloc (seq
, if_info
->jump
,
899 INSN_LOCATOR (if_info
->insn_a
));
909 /* Convert "if (test) x = a; else x = b", for A and B constant. */
912 noce_try_store_flag_constants (struct noce_if_info
*if_info
)
916 HOST_WIDE_INT itrue
, ifalse
, diff
, tmp
;
917 int normalize
, can_reverse
;
918 enum machine_mode mode
;
921 && GET_CODE (if_info
->a
) == CONST_INT
922 && GET_CODE (if_info
->b
) == CONST_INT
)
924 mode
= GET_MODE (if_info
->x
);
925 ifalse
= INTVAL (if_info
->a
);
926 itrue
= INTVAL (if_info
->b
);
928 /* Make sure we can represent the difference between the two values. */
929 if ((itrue
- ifalse
> 0)
930 != ((ifalse
< 0) != (itrue
< 0) ? ifalse
< 0 : ifalse
< itrue
))
933 diff
= trunc_int_for_mode (itrue
- ifalse
, mode
);
935 can_reverse
= (reversed_comparison_code (if_info
->cond
, if_info
->jump
)
939 if (diff
== STORE_FLAG_VALUE
|| diff
== -STORE_FLAG_VALUE
)
941 else if (ifalse
== 0 && exact_log2 (itrue
) >= 0
942 && (STORE_FLAG_VALUE
== 1
943 || BRANCH_COST
>= 2))
945 else if (itrue
== 0 && exact_log2 (ifalse
) >= 0 && can_reverse
946 && (STORE_FLAG_VALUE
== 1 || BRANCH_COST
>= 2))
947 normalize
= 1, reversep
= 1;
949 && (STORE_FLAG_VALUE
== -1
950 || BRANCH_COST
>= 2))
952 else if (ifalse
== -1 && can_reverse
953 && (STORE_FLAG_VALUE
== -1 || BRANCH_COST
>= 2))
954 normalize
= -1, reversep
= 1;
955 else if ((BRANCH_COST
>= 2 && STORE_FLAG_VALUE
== -1)
963 tmp
= itrue
; itrue
= ifalse
; ifalse
= tmp
;
964 diff
= trunc_int_for_mode (-diff
, mode
);
968 target
= noce_emit_store_flag (if_info
, if_info
->x
, reversep
, normalize
);
975 /* if (test) x = 3; else x = 4;
976 => x = 3 + (test == 0); */
977 if (diff
== STORE_FLAG_VALUE
|| diff
== -STORE_FLAG_VALUE
)
979 target
= expand_simple_binop (mode
,
980 (diff
== STORE_FLAG_VALUE
982 GEN_INT (ifalse
), target
, if_info
->x
, 0,
986 /* if (test) x = 8; else x = 0;
987 => x = (test != 0) << 3; */
988 else if (ifalse
== 0 && (tmp
= exact_log2 (itrue
)) >= 0)
990 target
= expand_simple_binop (mode
, ASHIFT
,
991 target
, GEN_INT (tmp
), if_info
->x
, 0,
995 /* if (test) x = -1; else x = b;
996 => x = -(test != 0) | b; */
997 else if (itrue
== -1)
999 target
= expand_simple_binop (mode
, IOR
,
1000 target
, GEN_INT (ifalse
), if_info
->x
, 0,
1004 /* if (test) x = a; else x = b;
1005 => x = (-(test != 0) & (b - a)) + a; */
1008 target
= expand_simple_binop (mode
, AND
,
1009 target
, GEN_INT (diff
), if_info
->x
, 0,
1012 target
= expand_simple_binop (mode
, PLUS
,
1013 target
, GEN_INT (ifalse
),
1014 if_info
->x
, 0, OPTAB_WIDEN
);
1023 if (target
!= if_info
->x
)
1024 noce_emit_move_insn (if_info
->x
, target
);
1026 seq
= end_ifcvt_sequence (if_info
);
1030 emit_insn_before_setloc (seq
, if_info
->jump
,
1031 INSN_LOCATOR (if_info
->insn_a
));
1038 /* Convert "if (test) foo++" into "foo += (test != 0)", and
1039 similarly for "foo--". */
1042 noce_try_addcc (struct noce_if_info
*if_info
)
1045 int subtract
, normalize
;
1047 if (! no_new_pseudos
1048 && GET_CODE (if_info
->a
) == PLUS
1049 && rtx_equal_p (XEXP (if_info
->a
, 0), if_info
->b
)
1050 && (reversed_comparison_code (if_info
->cond
, if_info
->jump
)
1053 rtx cond
= if_info
->cond
;
1054 enum rtx_code code
= reversed_comparison_code (cond
, if_info
->jump
);
1056 /* First try to use addcc pattern. */
1057 if (general_operand (XEXP (cond
, 0), VOIDmode
)
1058 && general_operand (XEXP (cond
, 1), VOIDmode
))
1061 target
= emit_conditional_add (if_info
->x
, code
,
1066 XEXP (if_info
->a
, 1),
1067 GET_MODE (if_info
->x
),
1068 (code
== LTU
|| code
== GEU
1069 || code
== LEU
|| code
== GTU
));
1072 if (target
!= if_info
->x
)
1073 noce_emit_move_insn (if_info
->x
, target
);
1075 seq
= end_ifcvt_sequence (if_info
);
1079 emit_insn_before_setloc (seq
, if_info
->jump
,
1080 INSN_LOCATOR (if_info
->insn_a
));
1086 /* If that fails, construct conditional increment or decrement using
1088 if (BRANCH_COST
>= 2
1089 && (XEXP (if_info
->a
, 1) == const1_rtx
1090 || XEXP (if_info
->a
, 1) == constm1_rtx
))
1093 if (STORE_FLAG_VALUE
== INTVAL (XEXP (if_info
->a
, 1)))
1094 subtract
= 0, normalize
= 0;
1095 else if (-STORE_FLAG_VALUE
== INTVAL (XEXP (if_info
->a
, 1)))
1096 subtract
= 1, normalize
= 0;
1098 subtract
= 0, normalize
= INTVAL (XEXP (if_info
->a
, 1));
1101 target
= noce_emit_store_flag (if_info
,
1102 gen_reg_rtx (GET_MODE (if_info
->x
)),
1106 target
= expand_simple_binop (GET_MODE (if_info
->x
),
1107 subtract
? MINUS
: PLUS
,
1108 if_info
->b
, target
, if_info
->x
,
1112 if (target
!= if_info
->x
)
1113 noce_emit_move_insn (if_info
->x
, target
);
1115 seq
= end_ifcvt_sequence (if_info
);
1119 emit_insn_before_setloc (seq
, if_info
->jump
,
1120 INSN_LOCATOR (if_info
->insn_a
));
1130 /* Convert "if (test) x = 0;" to "x &= -(test == 0);" */
1133 noce_try_store_flag_mask (struct noce_if_info
*if_info
)
1139 if (! no_new_pseudos
1140 && (BRANCH_COST
>= 2
1141 || STORE_FLAG_VALUE
== -1)
1142 && ((if_info
->a
== const0_rtx
1143 && rtx_equal_p (if_info
->b
, if_info
->x
))
1144 || ((reversep
= (reversed_comparison_code (if_info
->cond
,
1147 && if_info
->b
== const0_rtx
1148 && rtx_equal_p (if_info
->a
, if_info
->x
))))
1151 target
= noce_emit_store_flag (if_info
,
1152 gen_reg_rtx (GET_MODE (if_info
->x
)),
1155 target
= expand_simple_binop (GET_MODE (if_info
->x
), AND
,
1157 target
, if_info
->x
, 0,
1162 if (target
!= if_info
->x
)
1163 noce_emit_move_insn (if_info
->x
, target
);
1165 seq
= end_ifcvt_sequence (if_info
);
1169 emit_insn_before_setloc (seq
, if_info
->jump
,
1170 INSN_LOCATOR (if_info
->insn_a
));
1180 /* Helper function for noce_try_cmove and noce_try_cmove_arith. */
1183 noce_emit_cmove (struct noce_if_info
*if_info
, rtx x
, enum rtx_code code
,
1184 rtx cmp_a
, rtx cmp_b
, rtx vfalse
, rtx vtrue
)
1186 /* If earliest == jump, try to build the cmove insn directly.
1187 This is helpful when combine has created some complex condition
1188 (like for alpha's cmovlbs) that we can't hope to regenerate
1189 through the normal interface. */
1191 if (if_info
->cond_earliest
== if_info
->jump
)
1195 tmp
= gen_rtx_fmt_ee (code
, GET_MODE (if_info
->cond
), cmp_a
, cmp_b
);
1196 tmp
= gen_rtx_IF_THEN_ELSE (GET_MODE (x
), tmp
, vtrue
, vfalse
);
1197 tmp
= gen_rtx_SET (VOIDmode
, x
, tmp
);
1200 tmp
= emit_insn (tmp
);
1202 if (recog_memoized (tmp
) >= 0)
1214 /* Don't even try if the comparison operands are weird. */
1215 if (! general_operand (cmp_a
, GET_MODE (cmp_a
))
1216 || ! general_operand (cmp_b
, GET_MODE (cmp_b
)))
1219 #if HAVE_conditional_move
1220 return emit_conditional_move (x
, code
, cmp_a
, cmp_b
, VOIDmode
,
1221 vtrue
, vfalse
, GET_MODE (x
),
1222 (code
== LTU
|| code
== GEU
1223 || code
== LEU
|| code
== GTU
));
1225 /* We'll never get here, as noce_process_if_block doesn't call the
1226 functions involved. Ifdef code, however, should be discouraged
1227 because it leads to typos in the code not selected. However,
1228 emit_conditional_move won't exist either. */
1233 /* Try only simple constants and registers here. More complex cases
1234 are handled in noce_try_cmove_arith after noce_try_store_flag_arith
1235 has had a go at it. */
1238 noce_try_cmove (struct noce_if_info
*if_info
)
1243 if ((CONSTANT_P (if_info
->a
) || register_operand (if_info
->a
, VOIDmode
))
1244 && (CONSTANT_P (if_info
->b
) || register_operand (if_info
->b
, VOIDmode
)))
1248 code
= GET_CODE (if_info
->cond
);
1249 target
= noce_emit_cmove (if_info
, if_info
->x
, code
,
1250 XEXP (if_info
->cond
, 0),
1251 XEXP (if_info
->cond
, 1),
1252 if_info
->a
, if_info
->b
);
1256 if (target
!= if_info
->x
)
1257 noce_emit_move_insn (if_info
->x
, target
);
1259 seq
= end_ifcvt_sequence (if_info
);
1263 emit_insn_before_setloc (seq
, if_info
->jump
,
1264 INSN_LOCATOR (if_info
->insn_a
));
1277 /* Try more complex cases involving conditional_move. */
1280 noce_try_cmove_arith (struct noce_if_info
*if_info
)
1292 /* A conditional move from two memory sources is equivalent to a
1293 conditional on their addresses followed by a load. Don't do this
1294 early because it'll screw alias analysis. Note that we've
1295 already checked for no side effects. */
1296 if (! no_new_pseudos
&& cse_not_expected
1297 && MEM_P (a
) && MEM_P (b
)
1298 && BRANCH_COST
>= 5)
1302 x
= gen_reg_rtx (Pmode
);
1306 /* ??? We could handle this if we knew that a load from A or B could
1307 not fault. This is also true if we've already loaded
1308 from the address along the path from ENTRY. */
1309 else if (may_trap_p (a
) || may_trap_p (b
))
1312 /* if (test) x = a + b; else x = c - d;
1319 code
= GET_CODE (if_info
->cond
);
1320 insn_a
= if_info
->insn_a
;
1321 insn_b
= if_info
->insn_b
;
1323 /* Total insn_rtx_cost should be smaller than branch cost. Exit
1324 if insn_rtx_cost can't be estimated. */
1327 insn_cost
= insn_rtx_cost (PATTERN (insn_a
));
1328 if (insn_cost
== 0 || insn_cost
> COSTS_N_INSNS (BRANCH_COST
))
1336 insn_cost
+= insn_rtx_cost (PATTERN (insn_b
));
1337 if (insn_cost
== 0 || insn_cost
> COSTS_N_INSNS (BRANCH_COST
))
1341 /* Possibly rearrange operands to make things come out more natural. */
1342 if (reversed_comparison_code (if_info
->cond
, if_info
->jump
) != UNKNOWN
)
1345 if (rtx_equal_p (b
, x
))
1347 else if (general_operand (b
, GET_MODE (b
)))
1352 code
= reversed_comparison_code (if_info
->cond
, if_info
->jump
);
1353 tmp
= a
, a
= b
, b
= tmp
;
1354 tmp
= insn_a
, insn_a
= insn_b
, insn_b
= tmp
;
1363 /* If either operand is complex, load it into a register first.
1364 The best way to do this is to copy the original insn. In this
1365 way we preserve any clobbers etc that the insn may have had.
1366 This is of course not possible in the IS_MEM case. */
1367 if (! general_operand (a
, GET_MODE (a
)))
1372 goto end_seq_and_fail
;
1376 tmp
= gen_reg_rtx (GET_MODE (a
));
1377 tmp
= emit_insn (gen_rtx_SET (VOIDmode
, tmp
, a
));
1380 goto end_seq_and_fail
;
1383 a
= gen_reg_rtx (GET_MODE (a
));
1384 tmp
= copy_rtx (insn_a
);
1385 set
= single_set (tmp
);
1387 tmp
= emit_insn (PATTERN (tmp
));
1389 if (recog_memoized (tmp
) < 0)
1390 goto end_seq_and_fail
;
1392 if (! general_operand (b
, GET_MODE (b
)))
1397 goto end_seq_and_fail
;
1401 tmp
= gen_reg_rtx (GET_MODE (b
));
1402 tmp
= gen_rtx_SET (VOIDmode
, tmp
, b
);
1405 goto end_seq_and_fail
;
1408 b
= gen_reg_rtx (GET_MODE (b
));
1409 tmp
= copy_rtx (insn_b
);
1410 set
= single_set (tmp
);
1412 tmp
= PATTERN (tmp
);
1415 /* If insn to set up A clobbers any registers B depends on, try to
1416 swap insn that sets up A with the one that sets up B. If even
1417 that doesn't help, punt. */
1418 last
= get_last_insn ();
1419 if (last
&& modified_in_p (orig_b
, last
))
1421 tmp
= emit_insn_before (tmp
, get_insns ());
1422 if (modified_in_p (orig_a
, tmp
))
1423 goto end_seq_and_fail
;
1426 tmp
= emit_insn (tmp
);
1428 if (recog_memoized (tmp
) < 0)
1429 goto end_seq_and_fail
;
1432 target
= noce_emit_cmove (if_info
, x
, code
, XEXP (if_info
->cond
, 0),
1433 XEXP (if_info
->cond
, 1), a
, b
);
1436 goto end_seq_and_fail
;
1438 /* If we're handling a memory for above, emit the load now. */
1441 tmp
= gen_rtx_MEM (GET_MODE (if_info
->x
), target
);
1443 /* Copy over flags as appropriate. */
1444 if (MEM_VOLATILE_P (if_info
->a
) || MEM_VOLATILE_P (if_info
->b
))
1445 MEM_VOLATILE_P (tmp
) = 1;
1446 if (MEM_IN_STRUCT_P (if_info
->a
) && MEM_IN_STRUCT_P (if_info
->b
))
1447 MEM_IN_STRUCT_P (tmp
) = 1;
1448 if (MEM_SCALAR_P (if_info
->a
) && MEM_SCALAR_P (if_info
->b
))
1449 MEM_SCALAR_P (tmp
) = 1;
1450 if (MEM_ALIAS_SET (if_info
->a
) == MEM_ALIAS_SET (if_info
->b
))
1451 set_mem_alias_set (tmp
, MEM_ALIAS_SET (if_info
->a
));
1453 MIN (MEM_ALIGN (if_info
->a
), MEM_ALIGN (if_info
->b
)));
1455 noce_emit_move_insn (if_info
->x
, tmp
);
1457 else if (target
!= x
)
1458 noce_emit_move_insn (x
, target
);
1460 tmp
= end_ifcvt_sequence (if_info
);
1464 emit_insn_before_setloc (tmp
, if_info
->jump
, INSN_LOCATOR (if_info
->insn_a
));
1472 /* For most cases, the simplified condition we found is the best
1473 choice, but this is not the case for the min/max/abs transforms.
1474 For these we wish to know that it is A or B in the condition. */
1477 noce_get_alt_condition (struct noce_if_info
*if_info
, rtx target
,
1480 rtx cond
, set
, insn
;
1483 /* If target is already mentioned in the known condition, return it. */
1484 if (reg_mentioned_p (target
, if_info
->cond
))
1486 *earliest
= if_info
->cond_earliest
;
1487 return if_info
->cond
;
1490 set
= pc_set (if_info
->jump
);
1491 cond
= XEXP (SET_SRC (set
), 0);
1493 = GET_CODE (XEXP (SET_SRC (set
), 2)) == LABEL_REF
1494 && XEXP (XEXP (SET_SRC (set
), 2), 0) == JUMP_LABEL (if_info
->jump
);
1496 /* If we're looking for a constant, try to make the conditional
1497 have that constant in it. There are two reasons why it may
1498 not have the constant we want:
1500 1. GCC may have needed to put the constant in a register, because
1501 the target can't compare directly against that constant. For
1502 this case, we look for a SET immediately before the comparison
1503 that puts a constant in that register.
1505 2. GCC may have canonicalized the conditional, for example
1506 replacing "if x < 4" with "if x <= 3". We can undo that (or
1507 make equivalent types of changes) to get the constants we need
1508 if they're off by one in the right direction. */
1510 if (GET_CODE (target
) == CONST_INT
)
1512 enum rtx_code code
= GET_CODE (if_info
->cond
);
1513 rtx op_a
= XEXP (if_info
->cond
, 0);
1514 rtx op_b
= XEXP (if_info
->cond
, 1);
1517 /* First, look to see if we put a constant in a register. */
1518 prev_insn
= prev_nonnote_insn (if_info
->cond_earliest
);
1520 && INSN_P (prev_insn
)
1521 && GET_CODE (PATTERN (prev_insn
)) == SET
)
1523 rtx src
= find_reg_equal_equiv_note (prev_insn
);
1525 src
= SET_SRC (PATTERN (prev_insn
));
1526 if (GET_CODE (src
) == CONST_INT
)
1528 if (rtx_equal_p (op_a
, SET_DEST (PATTERN (prev_insn
))))
1530 else if (rtx_equal_p (op_b
, SET_DEST (PATTERN (prev_insn
))))
1533 if (GET_CODE (op_a
) == CONST_INT
)
1538 code
= swap_condition (code
);
1543 /* Now, look to see if we can get the right constant by
1544 adjusting the conditional. */
1545 if (GET_CODE (op_b
) == CONST_INT
)
1547 HOST_WIDE_INT desired_val
= INTVAL (target
);
1548 HOST_WIDE_INT actual_val
= INTVAL (op_b
);
1553 if (actual_val
== desired_val
+ 1)
1556 op_b
= GEN_INT (desired_val
);
1560 if (actual_val
== desired_val
- 1)
1563 op_b
= GEN_INT (desired_val
);
1567 if (actual_val
== desired_val
- 1)
1570 op_b
= GEN_INT (desired_val
);
1574 if (actual_val
== desired_val
+ 1)
1577 op_b
= GEN_INT (desired_val
);
1585 /* If we made any changes, generate a new conditional that is
1586 equivalent to what we started with, but has the right
1588 if (code
!= GET_CODE (if_info
->cond
)
1589 || op_a
!= XEXP (if_info
->cond
, 0)
1590 || op_b
!= XEXP (if_info
->cond
, 1))
1592 cond
= gen_rtx_fmt_ee (code
, GET_MODE (cond
), op_a
, op_b
);
1593 *earliest
= if_info
->cond_earliest
;
1598 cond
= canonicalize_condition (if_info
->jump
, cond
, reverse
,
1599 earliest
, target
, false, true);
1600 if (! cond
|| ! reg_mentioned_p (target
, cond
))
1603 /* We almost certainly searched back to a different place.
1604 Need to re-verify correct lifetimes. */
1606 /* X may not be mentioned in the range (cond_earliest, jump]. */
1607 for (insn
= if_info
->jump
; insn
!= *earliest
; insn
= PREV_INSN (insn
))
1608 if (INSN_P (insn
) && reg_overlap_mentioned_p (if_info
->x
, PATTERN (insn
)))
1611 /* A and B may not be modified in the range [cond_earliest, jump). */
1612 for (insn
= *earliest
; insn
!= if_info
->jump
; insn
= NEXT_INSN (insn
))
1614 && (modified_in_p (if_info
->a
, insn
)
1615 || modified_in_p (if_info
->b
, insn
)))
1621 /* Convert "if (a < b) x = a; else x = b;" to "x = min(a, b);", etc. */
1624 noce_try_minmax (struct noce_if_info
*if_info
)
1626 rtx cond
, earliest
, target
, seq
;
1627 enum rtx_code code
, op
;
1630 /* ??? Can't guarantee that expand_binop won't create pseudos. */
1634 /* ??? Reject modes with NaNs or signed zeros since we don't know how
1635 they will be resolved with an SMIN/SMAX. It wouldn't be too hard
1636 to get the target to tell us... */
1637 if (HONOR_SIGNED_ZEROS (GET_MODE (if_info
->x
))
1638 || HONOR_NANS (GET_MODE (if_info
->x
)))
1641 cond
= noce_get_alt_condition (if_info
, if_info
->a
, &earliest
);
1645 /* Verify the condition is of the form we expect, and canonicalize
1646 the comparison code. */
1647 code
= GET_CODE (cond
);
1648 if (rtx_equal_p (XEXP (cond
, 0), if_info
->a
))
1650 if (! rtx_equal_p (XEXP (cond
, 1), if_info
->b
))
1653 else if (rtx_equal_p (XEXP (cond
, 1), if_info
->a
))
1655 if (! rtx_equal_p (XEXP (cond
, 0), if_info
->b
))
1657 code
= swap_condition (code
);
1662 /* Determine what sort of operation this is. Note that the code is for
1663 a taken branch, so the code->operation mapping appears backwards. */
1696 target
= expand_simple_binop (GET_MODE (if_info
->x
), op
,
1697 if_info
->a
, if_info
->b
,
1698 if_info
->x
, unsignedp
, OPTAB_WIDEN
);
1704 if (target
!= if_info
->x
)
1705 noce_emit_move_insn (if_info
->x
, target
);
1707 seq
= end_ifcvt_sequence (if_info
);
1711 emit_insn_before_setloc (seq
, if_info
->jump
, INSN_LOCATOR (if_info
->insn_a
));
1712 if_info
->cond
= cond
;
1713 if_info
->cond_earliest
= earliest
;
1718 /* Convert "if (a < 0) x = -a; else x = a;" to "x = abs(a);", etc. */
1721 noce_try_abs (struct noce_if_info
*if_info
)
1723 rtx cond
, earliest
, target
, seq
, a
, b
, c
;
1726 /* ??? Can't guarantee that expand_binop won't create pseudos. */
1730 /* Recognize A and B as constituting an ABS or NABS. The canonical
1731 form is a branch around the negation, taken when the object is the
1732 first operand of a comparison against 0 that evaluates to true. */
1735 if (GET_CODE (a
) == NEG
&& rtx_equal_p (XEXP (a
, 0), b
))
1737 else if (GET_CODE (b
) == NEG
&& rtx_equal_p (XEXP (b
, 0), a
))
1739 c
= a
; a
= b
; b
= c
;
1745 cond
= noce_get_alt_condition (if_info
, b
, &earliest
);
1749 /* Verify the condition is of the form we expect. */
1750 if (rtx_equal_p (XEXP (cond
, 0), b
))
1752 else if (rtx_equal_p (XEXP (cond
, 1), b
))
1760 /* Verify that C is zero. Search one step backward for a
1761 REG_EQUAL note or a simple source if necessary. */
1764 rtx set
, insn
= prev_nonnote_insn (earliest
);
1766 && (set
= single_set (insn
))
1767 && rtx_equal_p (SET_DEST (set
), c
))
1769 rtx note
= find_reg_equal_equiv_note (insn
);
1779 && GET_CODE (XEXP (c
, 0)) == SYMBOL_REF
1780 && CONSTANT_POOL_ADDRESS_P (XEXP (c
, 0)))
1781 c
= get_pool_constant (XEXP (c
, 0));
1783 /* Work around funny ideas get_condition has wrt canonicalization.
1784 Note that these rtx constants are known to be CONST_INT, and
1785 therefore imply integer comparisons. */
1786 if (c
== constm1_rtx
&& GET_CODE (cond
) == GT
)
1788 else if (c
== const1_rtx
&& GET_CODE (cond
) == LT
)
1790 else if (c
!= CONST0_RTX (GET_MODE (b
)))
1793 /* Determine what sort of operation this is. */
1794 switch (GET_CODE (cond
))
1813 target
= expand_abs_nojump (GET_MODE (if_info
->x
), b
, if_info
->x
, 1);
1815 /* ??? It's a quandary whether cmove would be better here, especially
1816 for integers. Perhaps combine will clean things up. */
1817 if (target
&& negate
)
1818 target
= expand_simple_unop (GET_MODE (target
), NEG
, target
, if_info
->x
, 0);
1826 if (target
!= if_info
->x
)
1827 noce_emit_move_insn (if_info
->x
, target
);
1829 seq
= end_ifcvt_sequence (if_info
);
1833 emit_insn_before_setloc (seq
, if_info
->jump
, INSN_LOCATOR (if_info
->insn_a
));
1834 if_info
->cond
= cond
;
1835 if_info
->cond_earliest
= earliest
;
1840 /* Convert "if (m < 0) x = b; else x = 0;" to "x = (m >> C) & b;". */
1843 noce_try_sign_mask (struct noce_if_info
*if_info
)
1845 rtx cond
, t
, m
, c
, seq
;
1846 enum machine_mode mode
;
1852 cond
= if_info
->cond
;
1853 code
= GET_CODE (cond
);
1858 if (if_info
->a
== const0_rtx
)
1860 if ((code
== LT
&& c
== const0_rtx
)
1861 || (code
== LE
&& c
== constm1_rtx
))
1864 else if (if_info
->b
== const0_rtx
)
1866 if ((code
== GE
&& c
== const0_rtx
)
1867 || (code
== GT
&& c
== constm1_rtx
))
1871 if (! t
|| side_effects_p (t
))
1874 /* We currently don't handle different modes. */
1875 mode
= GET_MODE (t
);
1876 if (GET_MODE (m
) != mode
)
1879 /* This is only profitable if T is cheap, or T is unconditionally
1880 executed/evaluated in the original insn sequence. */
1881 if (rtx_cost (t
, SET
) >= COSTS_N_INSNS (2)
1882 && (!if_info
->b_unconditional
1883 || t
!= if_info
->b
))
1887 /* Use emit_store_flag to generate "m < 0 ? -1 : 0" instead of expanding
1888 "(signed) m >> 31" directly. This benefits targets with specialized
1889 insns to obtain the signmask, but still uses ashr_optab otherwise. */
1890 m
= emit_store_flag (gen_reg_rtx (mode
), LT
, m
, const0_rtx
, mode
, 0, -1);
1891 t
= m
? expand_binop (mode
, and_optab
, m
, t
, NULL_RTX
, 0, OPTAB_DIRECT
)
1900 noce_emit_move_insn (if_info
->x
, t
);
1902 seq
= end_ifcvt_sequence (if_info
);
1906 emit_insn_before_setloc (seq
, if_info
->jump
, INSN_LOCATOR (if_info
->insn_a
));
1911 /* Optimize away "if (x & C) x |= C" and similar bit manipulation
1915 noce_try_bitop (struct noce_if_info
*if_info
)
1917 rtx cond
, x
, a
, result
, seq
;
1918 enum machine_mode mode
;
1923 cond
= if_info
->cond
;
1924 code
= GET_CODE (cond
);
1926 /* Check for no else condition. */
1927 if (! rtx_equal_p (x
, if_info
->b
))
1930 /* Check for a suitable condition. */
1931 if (code
!= NE
&& code
!= EQ
)
1933 if (XEXP (cond
, 1) != const0_rtx
)
1935 cond
= XEXP (cond
, 0);
1937 /* ??? We could also handle AND here. */
1938 if (GET_CODE (cond
) == ZERO_EXTRACT
)
1940 if (XEXP (cond
, 1) != const1_rtx
1941 || GET_CODE (XEXP (cond
, 2)) != CONST_INT
1942 || ! rtx_equal_p (x
, XEXP (cond
, 0)))
1944 bitnum
= INTVAL (XEXP (cond
, 2));
1945 mode
= GET_MODE (x
);
1946 if (BITS_BIG_ENDIAN
)
1947 bitnum
= GET_MODE_BITSIZE (mode
) - 1 - bitnum
;
1948 if (bitnum
< 0 || bitnum
>= HOST_BITS_PER_WIDE_INT
)
1955 if (GET_CODE (a
) == IOR
|| GET_CODE (a
) == XOR
)
1957 /* Check for "if (X & C) x = x op C". */
1958 if (! rtx_equal_p (x
, XEXP (a
, 0))
1959 || GET_CODE (XEXP (a
, 1)) != CONST_INT
1960 || (INTVAL (XEXP (a
, 1)) & GET_MODE_MASK (mode
))
1961 != (unsigned HOST_WIDE_INT
) 1 << bitnum
)
1964 /* if ((x & C) == 0) x |= C; is transformed to x |= C. */
1965 /* if ((x & C) != 0) x |= C; is transformed to nothing. */
1966 if (GET_CODE (a
) == IOR
)
1967 result
= (code
== NE
) ? a
: NULL_RTX
;
1968 else if (code
== NE
)
1970 /* if ((x & C) == 0) x ^= C; is transformed to x |= C. */
1971 result
= gen_int_mode ((HOST_WIDE_INT
) 1 << bitnum
, mode
);
1972 result
= simplify_gen_binary (IOR
, mode
, x
, result
);
1976 /* if ((x & C) != 0) x ^= C; is transformed to x &= ~C. */
1977 result
= gen_int_mode (~((HOST_WIDE_INT
) 1 << bitnum
), mode
);
1978 result
= simplify_gen_binary (AND
, mode
, x
, result
);
1981 else if (GET_CODE (a
) == AND
)
1983 /* Check for "if (X & C) x &= ~C". */
1984 if (! rtx_equal_p (x
, XEXP (a
, 0))
1985 || GET_CODE (XEXP (a
, 1)) != CONST_INT
1986 || (INTVAL (XEXP (a
, 1)) & GET_MODE_MASK (mode
))
1987 != (~((HOST_WIDE_INT
) 1 << bitnum
) & GET_MODE_MASK (mode
)))
1990 /* if ((x & C) == 0) x &= ~C; is transformed to nothing. */
1991 /* if ((x & C) != 0) x &= ~C; is transformed to x &= ~C. */
1992 result
= (code
== EQ
) ? a
: NULL_RTX
;
2000 noce_emit_move_insn (x
, result
);
2001 seq
= end_ifcvt_sequence (if_info
);
2005 emit_insn_before_setloc (seq
, if_info
->jump
,
2006 INSN_LOCATOR (if_info
->insn_a
));
2012 /* Similar to get_condition, only the resulting condition must be
2013 valid at JUMP, instead of at EARLIEST. */
2016 noce_get_condition (rtx jump
, rtx
*earliest
)
2021 if (! any_condjump_p (jump
))
2024 set
= pc_set (jump
);
2026 /* If this branches to JUMP_LABEL when the condition is false,
2027 reverse the condition. */
2028 reverse
= (GET_CODE (XEXP (SET_SRC (set
), 2)) == LABEL_REF
2029 && XEXP (XEXP (SET_SRC (set
), 2), 0) == JUMP_LABEL (jump
));
2031 /* If the condition variable is a register and is MODE_INT, accept it. */
2033 cond
= XEXP (SET_SRC (set
), 0);
2034 tmp
= XEXP (cond
, 0);
2035 if (REG_P (tmp
) && GET_MODE_CLASS (GET_MODE (tmp
)) == MODE_INT
)
2040 cond
= gen_rtx_fmt_ee (reverse_condition (GET_CODE (cond
)),
2041 GET_MODE (cond
), tmp
, XEXP (cond
, 1));
2045 /* Otherwise, fall back on canonicalize_condition to do the dirty
2046 work of manipulating MODE_CC values and COMPARE rtx codes. */
2047 return canonicalize_condition (jump
, cond
, reverse
, earliest
,
2048 NULL_RTX
, false, true);
2051 /* Initialize for a simple IF-THEN or IF-THEN-ELSE block. We will not
2052 be using conditional execution. Set some fields of IF_INFO based
2053 on CE_INFO: test_bb, cond, jump, cond_earliest. Return TRUE if
2057 noce_init_if_info (struct ce_if_block
*ce_info
, struct noce_if_info
*if_info
)
2059 basic_block test_bb
= ce_info
->test_bb
;
2062 /* If test is comprised of && or || elements, don't handle it unless
2063 it is the special case of && elements without an ELSE block. */
2064 if (ce_info
->num_multiple_test_blocks
)
2066 if (ce_info
->else_bb
|| !ce_info
->and_and_p
)
2069 ce_info
->test_bb
= test_bb
= ce_info
->last_test_bb
;
2070 ce_info
->num_multiple_test_blocks
= 0;
2071 ce_info
->num_and_and_blocks
= 0;
2072 ce_info
->num_or_or_blocks
= 0;
2075 /* If this is not a standard conditional jump, we can't parse it. */
2076 jump
= BB_END (test_bb
);
2077 cond
= noce_get_condition (jump
, &if_info
->cond_earliest
);
2081 /* If the conditional jump is more than just a conditional
2082 jump, then we can not do if-conversion on this block. */
2083 if (! onlyjump_p (jump
))
2086 /* We must be comparing objects whose modes imply the size. */
2087 if (GET_MODE (XEXP (cond
, 0)) == BLKmode
)
2090 if_info
->test_bb
= test_bb
;
2091 if_info
->cond
= cond
;
2092 if_info
->jump
= jump
;
2097 /* Return true if OP is ok for if-then-else processing. */
2100 noce_operand_ok (rtx op
)
2102 /* We special-case memories, so handle any of them with
2103 no address side effects. */
2105 return ! side_effects_p (XEXP (op
, 0));
2107 if (side_effects_p (op
))
2110 return ! may_trap_p (op
);
2113 /* Return true if a write into MEM may trap or fault. */
2116 noce_mem_write_may_trap_or_fault_p (rtx mem
)
2120 if (MEM_READONLY_P (mem
))
2123 if (may_trap_or_fault_p (mem
))
2126 addr
= XEXP (mem
, 0);
2128 /* Call target hook to avoid the effects of -fpic etc.... */
2129 addr
= targetm
.delegitimize_address (addr
);
2132 switch (GET_CODE (addr
))
2140 addr
= XEXP (addr
, 0);
2144 addr
= XEXP (addr
, 1);
2147 if (GET_CODE (XEXP (addr
, 1)) == CONST_INT
)
2148 addr
= XEXP (addr
, 0);
2155 if (SYMBOL_REF_DECL (addr
)
2156 && decl_readonly_section (SYMBOL_REF_DECL (addr
), 0))
2166 /* Given a simple IF-THEN or IF-THEN-ELSE block, attempt to convert it
2167 without using conditional execution. Return TRUE if we were
2168 successful at converting the block. */
2171 noce_process_if_block (struct ce_if_block
* ce_info
)
2173 basic_block test_bb
= ce_info
->test_bb
; /* 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 struct noce_if_info if_info
;
2179 rtx orig_x
, x
, a
, b
;
2182 /* We're looking for patterns of the form
2184 (1) if (...) x = a; else x = b;
2185 (2) x = b; if (...) x = a;
2186 (3) if (...) x = a; // as if with an initial x = x.
2188 The later patterns require jumps to be more expensive.
2190 ??? For future expansion, look for multiple X in such patterns. */
2192 if (!noce_init_if_info (ce_info
, &if_info
))
2195 cond
= if_info
.cond
;
2196 jump
= if_info
.jump
;
2198 /* Look for one of the potential sets. */
2199 insn_a
= first_active_insn (then_bb
);
2201 || insn_a
!= last_active_insn (then_bb
, FALSE
)
2202 || (set_a
= single_set (insn_a
)) == NULL_RTX
)
2205 x
= SET_DEST (set_a
);
2206 a
= SET_SRC (set_a
);
2208 /* Look for the other potential set. Make sure we've got equivalent
2210 /* ??? This is overconservative. Storing to two different mems is
2211 as easy as conditionally computing the address. Storing to a
2212 single mem merely requires a scratch memory to use as one of the
2213 destination addresses; often the memory immediately below the
2214 stack pointer is available for this. */
2218 insn_b
= first_active_insn (else_bb
);
2220 || insn_b
!= last_active_insn (else_bb
, FALSE
)
2221 || (set_b
= single_set (insn_b
)) == NULL_RTX
2222 || ! rtx_equal_p (x
, SET_DEST (set_b
)))
2227 insn_b
= prev_nonnote_insn (if_info
.cond_earliest
);
2228 /* We're going to be moving the evaluation of B down from above
2229 COND_EARLIEST to JUMP. Make sure the relevant data is still
2232 || !NONJUMP_INSN_P (insn_b
)
2233 || (set_b
= single_set (insn_b
)) == NULL_RTX
2234 || ! rtx_equal_p (x
, SET_DEST (set_b
))
2235 || reg_overlap_mentioned_p (x
, SET_SRC (set_b
))
2236 || modified_between_p (SET_SRC (set_b
),
2237 PREV_INSN (if_info
.cond_earliest
), jump
)
2238 /* Likewise with X. In particular this can happen when
2239 noce_get_condition looks farther back in the instruction
2240 stream than one might expect. */
2241 || reg_overlap_mentioned_p (x
, cond
)
2242 || reg_overlap_mentioned_p (x
, a
)
2243 || modified_between_p (x
, PREV_INSN (if_info
.cond_earliest
), jump
))
2244 insn_b
= set_b
= NULL_RTX
;
2247 /* If x has side effects then only the if-then-else form is safe to
2248 convert. But even in that case we would need to restore any notes
2249 (such as REG_INC) at then end. That can be tricky if
2250 noce_emit_move_insn expands to more than one insn, so disable the
2251 optimization entirely for now if there are side effects. */
2252 if (side_effects_p (x
))
2255 b
= (set_b
? SET_SRC (set_b
) : x
);
2257 /* Only operate on register destinations, and even then avoid extending
2258 the lifetime of hard registers on small register class machines. */
2261 || (SMALL_REGISTER_CLASSES
2262 && REGNO (x
) < FIRST_PSEUDO_REGISTER
))
2264 if (no_new_pseudos
|| GET_MODE (x
) == BLKmode
)
2267 if (GET_MODE (x
) == ZERO_EXTRACT
2268 && (GET_CODE (XEXP (x
, 1)) != CONST_INT
2269 || GET_CODE (XEXP (x
, 2)) != CONST_INT
))
2272 x
= gen_reg_rtx (GET_MODE (GET_CODE (x
) == STRICT_LOW_PART
2273 ? XEXP (x
, 0) : x
));
2276 /* Don't operate on sources that may trap or are volatile. */
2277 if (! noce_operand_ok (a
) || ! noce_operand_ok (b
))
2280 /* Set up the info block for our subroutines. */
2281 if_info
.insn_a
= insn_a
;
2282 if_info
.insn_b
= insn_b
;
2286 if_info
.b_unconditional
= else_bb
== 0;
2288 /* Try optimizations in some approximation of a useful order. */
2289 /* ??? Should first look to see if X is live incoming at all. If it
2290 isn't, we don't need anything but an unconditional set. */
2292 /* Look and see if A and B are really the same. Avoid creating silly
2293 cmove constructs that no one will fix up later. */
2294 if (rtx_equal_p (a
, b
))
2296 /* If we have an INSN_B, we don't have to create any new rtl. Just
2297 move the instruction that we already have. If we don't have an
2298 INSN_B, that means that A == X, and we've got a noop move. In
2299 that case don't do anything and let the code below delete INSN_A. */
2300 if (insn_b
&& else_bb
)
2304 if (else_bb
&& insn_b
== BB_END (else_bb
))
2305 BB_END (else_bb
) = PREV_INSN (insn_b
);
2306 reorder_insns (insn_b
, insn_b
, PREV_INSN (jump
));
2308 /* If there was a REG_EQUAL note, delete it since it may have been
2309 true due to this insn being after a jump. */
2310 if ((note
= find_reg_note (insn_b
, REG_EQUAL
, NULL_RTX
)) != 0)
2311 remove_note (insn_b
, note
);
2315 /* If we have "x = b; if (...) x = a;", and x has side-effects, then
2316 x must be executed twice. */
2317 else if (insn_b
&& side_effects_p (orig_x
))
2324 /* Disallow the "if (...) x = a;" form (with an implicit "else x = x;")
2325 for optimizations if writing to x may trap or fault, i.e. it's a memory
2326 other than a static var or a stack slot, is misaligned on strict
2327 aligned machines or is read-only.
2328 If x is a read-only memory, then the program is valid only if we
2329 avoid the store into it. If there are stores on both the THEN and
2330 ELSE arms, then we can go ahead with the conversion; either the
2331 program is broken, or the condition is always false such that the
2332 other memory is selected. */
2333 if (!set_b
&& MEM_P (orig_x
) && noce_mem_write_may_trap_or_fault_p (orig_x
))
2336 if (noce_try_move (&if_info
))
2338 if (noce_try_store_flag (&if_info
))
2340 if (noce_try_bitop (&if_info
))
2342 if (noce_try_minmax (&if_info
))
2344 if (noce_try_abs (&if_info
))
2346 if (HAVE_conditional_move
2347 && noce_try_cmove (&if_info
))
2349 if (! HAVE_conditional_execution
)
2351 if (noce_try_store_flag_constants (&if_info
))
2353 if (noce_try_addcc (&if_info
))
2355 if (noce_try_store_flag_mask (&if_info
))
2357 if (HAVE_conditional_move
2358 && noce_try_cmove_arith (&if_info
))
2360 if (noce_try_sign_mask (&if_info
))
2367 /* The original sets may now be killed. */
2368 delete_insn (insn_a
);
2370 /* Several special cases here: First, we may have reused insn_b above,
2371 in which case insn_b is now NULL. Second, we want to delete insn_b
2372 if it came from the ELSE block, because follows the now correct
2373 write that appears in the TEST block. However, if we got insn_b from
2374 the TEST block, it may in fact be loading data needed for the comparison.
2375 We'll let life_analysis remove the insn if it's really dead. */
2376 if (insn_b
&& else_bb
)
2377 delete_insn (insn_b
);
2379 /* The new insns will have been inserted immediately before the jump. We
2380 should be able to remove the jump with impunity, but the condition itself
2381 may have been modified by gcse to be shared across basic blocks. */
2384 /* If we used a temporary, fix it up now. */
2388 noce_emit_move_insn (orig_x
, x
);
2389 insn_b
= get_insns ();
2390 set_used_flags (orig_x
);
2391 unshare_all_rtl_in_chain (insn_b
);
2394 emit_insn_after_setloc (insn_b
, BB_END (test_bb
), INSN_LOCATOR (insn_a
));
2397 /* Merge the blocks! */
2398 merge_if_block (ce_info
);
2403 /* Check whether a block is suitable for conditional move conversion.
2404 Every insn must be a simple set of a register to a constant or a
2405 register. For each assignment, store the value in the array VALS,
2406 indexed by register number. COND is the condition we will
2410 check_cond_move_block (basic_block bb
, rtx
*vals
, rtx cond
)
2414 FOR_BB_INSNS (bb
, insn
)
2418 if (!INSN_P (insn
) || JUMP_P (insn
))
2420 set
= single_set (insn
);
2424 dest
= SET_DEST (set
);
2425 src
= SET_SRC (set
);
2427 || (SMALL_REGISTER_CLASSES
&& HARD_REGISTER_P (dest
)))
2430 if (!CONSTANT_P (src
) && !register_operand (src
, VOIDmode
))
2433 if (side_effects_p (src
) || side_effects_p (dest
))
2436 if (may_trap_p (src
) || may_trap_p (dest
))
2439 /* Don't try to handle this if the source register was
2440 modified earlier in the block. */
2442 && vals
[REGNO (src
)] != NULL
)
2443 || (GET_CODE (src
) == SUBREG
&& REG_P (SUBREG_REG (src
))
2444 && vals
[REGNO (SUBREG_REG (src
))] != NULL
))
2447 /* Don't try to handle this if the destination register was
2448 modified earlier in the block. */
2449 if (vals
[REGNO (dest
)] != NULL
)
2452 /* Don't try to handle this if the condition uses the
2453 destination register. */
2454 if (reg_overlap_mentioned_p (dest
, cond
))
2457 vals
[REGNO (dest
)] = src
;
2459 /* Don't try to handle this if the source register is modified
2460 later in the block. */
2461 if (!CONSTANT_P (src
)
2462 && modified_between_p (src
, insn
, NEXT_INSN (BB_END (bb
))))
2469 /* Given a simple IF-THEN or IF-THEN-ELSE block, attempt to convert it
2470 using only conditional moves. Return TRUE if we were successful at
2471 converting the block. */
2474 cond_move_process_if_block (struct ce_if_block
*ce_info
)
2476 basic_block then_bb
= ce_info
->then_bb
;
2477 basic_block else_bb
= ce_info
->else_bb
;
2478 struct noce_if_info if_info
;
2479 rtx jump
, cond
, insn
, seq
, cond_arg0
, cond_arg1
, loc_insn
;
2480 int max_reg
, size
, c
, i
;
2485 if (!HAVE_conditional_move
|| no_new_pseudos
)
2488 memset (&if_info
, 0, sizeof if_info
);
2490 if (!noce_init_if_info (ce_info
, &if_info
))
2493 cond
= if_info
.cond
;
2494 jump
= if_info
.jump
;
2496 /* Build a mapping for each block to the value used for each
2498 max_reg
= max_reg_num ();
2499 size
= (max_reg
+ 1) * sizeof (rtx
);
2500 then_vals
= (rtx
*) alloca (size
);
2501 else_vals
= (rtx
*) alloca (size
);
2502 memset (then_vals
, 0, size
);
2503 memset (else_vals
, 0, size
);
2505 /* Make sure the blocks are suitable. */
2506 if (!check_cond_move_block (then_bb
, then_vals
, cond
)
2507 || (else_bb
&& !check_cond_move_block (else_bb
, else_vals
, cond
)))
2510 /* Make sure the blocks can be used together. If the same register
2511 is set in both blocks, and is not set to a constant in both
2512 cases, then both blocks must set it to the same register. We
2513 have already verified that if it is set to a register, that the
2514 source register does not change after the assignment. Also count
2515 the number of registers set in only one of the blocks. */
2517 for (i
= 0; i
<= max_reg
; ++i
)
2519 if (!then_vals
[i
] && !else_vals
[i
])
2522 if (!then_vals
[i
] || !else_vals
[i
])
2526 if (!CONSTANT_P (then_vals
[i
])
2527 && !CONSTANT_P (else_vals
[i
])
2528 && !rtx_equal_p (then_vals
[i
], else_vals
[i
]))
2533 /* Make sure it is reasonable to convert this block. What matters
2534 is the number of assignments currently made in only one of the
2535 branches, since if we convert we are going to always execute
2537 if (c
> MAX_CONDITIONAL_EXECUTE
)
2540 /* Emit the conditional moves. First do the then block, then do
2541 anything left in the else blocks. */
2543 code
= GET_CODE (cond
);
2544 cond_arg0
= XEXP (cond
, 0);
2545 cond_arg1
= XEXP (cond
, 1);
2549 FOR_BB_INSNS (then_bb
, insn
)
2551 rtx set
, target
, dest
, t
, e
;
2554 if (!INSN_P (insn
) || JUMP_P (insn
))
2556 set
= single_set (insn
);
2557 gcc_assert (set
&& REG_P (SET_DEST (set
)));
2559 dest
= SET_DEST (set
);
2560 regno
= REGNO (dest
);
2561 t
= then_vals
[regno
];
2562 e
= else_vals
[regno
];
2566 target
= noce_emit_cmove (&if_info
, dest
, code
, cond_arg0
, cond_arg1
,
2575 noce_emit_move_insn (dest
, target
);
2580 FOR_BB_INSNS (else_bb
, insn
)
2582 rtx set
, target
, dest
;
2585 if (!INSN_P (insn
) || JUMP_P (insn
))
2587 set
= single_set (insn
);
2588 gcc_assert (set
&& REG_P (SET_DEST (set
)));
2590 dest
= SET_DEST (set
);
2591 regno
= REGNO (dest
);
2593 /* If this register was set in the then block, we already
2594 handled this case above. */
2595 if (then_vals
[regno
])
2597 gcc_assert (else_vals
[regno
]);
2599 target
= noce_emit_cmove (&if_info
, dest
, code
, cond_arg0
, cond_arg1
,
2600 dest
, else_vals
[regno
]);
2608 noce_emit_move_insn (dest
, target
);
2612 seq
= end_ifcvt_sequence (&if_info
);
2616 loc_insn
= first_active_insn (then_bb
);
2619 loc_insn
= first_active_insn (else_bb
);
2620 gcc_assert (loc_insn
);
2622 emit_insn_before_setloc (seq
, jump
, INSN_LOCATOR (loc_insn
));
2624 FOR_BB_INSNS (then_bb
, insn
)
2625 if (INSN_P (insn
) && !JUMP_P (insn
))
2629 FOR_BB_INSNS (else_bb
, insn
)
2630 if (INSN_P (insn
) && !JUMP_P (insn
))
2635 merge_if_block (ce_info
);
2640 /* Attempt to convert an IF-THEN or IF-THEN-ELSE block into
2641 straight line code. Return true if successful. */
2644 process_if_block (struct ce_if_block
* ce_info
)
2646 if (! reload_completed
2647 && noce_process_if_block (ce_info
))
2650 if (HAVE_conditional_move
2651 && cond_move_process_if_block (ce_info
))
2654 if (HAVE_conditional_execution
&& reload_completed
)
2656 /* If we have && and || tests, try to first handle combining the && and
2657 || tests into the conditional code, and if that fails, go back and
2658 handle it without the && and ||, which at present handles the && case
2659 if there was no ELSE block. */
2660 if (cond_exec_process_if_block (ce_info
, TRUE
))
2663 if (ce_info
->num_multiple_test_blocks
)
2667 if (cond_exec_process_if_block (ce_info
, FALSE
))
2675 /* Merge the blocks and mark for local life update. */
2678 merge_if_block (struct ce_if_block
* ce_info
)
2680 basic_block test_bb
= ce_info
->test_bb
; /* last test block */
2681 basic_block then_bb
= ce_info
->then_bb
; /* THEN */
2682 basic_block else_bb
= ce_info
->else_bb
; /* ELSE or NULL */
2683 basic_block join_bb
= ce_info
->join_bb
; /* join block */
2684 basic_block combo_bb
;
2686 /* All block merging is done into the lower block numbers. */
2690 /* Merge any basic blocks to handle && and || subtests. Each of
2691 the blocks are on the fallthru path from the predecessor block. */
2692 if (ce_info
->num_multiple_test_blocks
> 0)
2694 basic_block bb
= test_bb
;
2695 basic_block last_test_bb
= ce_info
->last_test_bb
;
2696 basic_block fallthru
= block_fallthru (bb
);
2701 fallthru
= block_fallthru (bb
);
2702 merge_blocks (combo_bb
, bb
);
2705 while (bb
!= last_test_bb
);
2708 /* Merge TEST block into THEN block. Normally the THEN block won't have a
2709 label, but it might if there were || tests. That label's count should be
2710 zero, and it normally should be removed. */
2714 if (combo_bb
->il
.rtl
->global_live_at_end
)
2715 COPY_REG_SET (combo_bb
->il
.rtl
->global_live_at_end
,
2716 then_bb
->il
.rtl
->global_live_at_end
);
2717 merge_blocks (combo_bb
, then_bb
);
2721 /* The ELSE block, if it existed, had a label. That label count
2722 will almost always be zero, but odd things can happen when labels
2723 get their addresses taken. */
2726 merge_blocks (combo_bb
, else_bb
);
2730 /* If there was no join block reported, that means it was not adjacent
2731 to the others, and so we cannot merge them. */
2735 rtx last
= BB_END (combo_bb
);
2737 /* The outgoing edge for the current COMBO block should already
2738 be correct. Verify this. */
2739 if (EDGE_COUNT (combo_bb
->succs
) == 0)
2740 gcc_assert (find_reg_note (last
, REG_NORETURN
, NULL
)
2741 || (NONJUMP_INSN_P (last
)
2742 && GET_CODE (PATTERN (last
)) == TRAP_IF
2743 && (TRAP_CONDITION (PATTERN (last
))
2744 == const_true_rtx
)));
2747 /* There should still be something at the end of the THEN or ELSE
2748 blocks taking us to our final destination. */
2749 gcc_assert (JUMP_P (last
)
2750 || (EDGE_SUCC (combo_bb
, 0)->dest
== EXIT_BLOCK_PTR
2752 && SIBLING_CALL_P (last
))
2753 || ((EDGE_SUCC (combo_bb
, 0)->flags
& EDGE_EH
)
2754 && can_throw_internal (last
)));
2757 /* The JOIN block may have had quite a number of other predecessors too.
2758 Since we've already merged the TEST, THEN and ELSE blocks, we should
2759 have only one remaining edge from our if-then-else diamond. If there
2760 is more than one remaining edge, it must come from elsewhere. There
2761 may be zero incoming edges if the THEN block didn't actually join
2762 back up (as with a call to a non-return function). */
2763 else if (EDGE_COUNT (join_bb
->preds
) < 2
2764 && join_bb
!= EXIT_BLOCK_PTR
)
2766 /* We can merge the JOIN. */
2767 if (combo_bb
->il
.rtl
->global_live_at_end
)
2768 COPY_REG_SET (combo_bb
->il
.rtl
->global_live_at_end
,
2769 join_bb
->il
.rtl
->global_live_at_end
);
2771 merge_blocks (combo_bb
, join_bb
);
2776 /* We cannot merge the JOIN. */
2778 /* The outgoing edge for the current COMBO block should already
2779 be correct. Verify this. */
2780 gcc_assert (single_succ_p (combo_bb
)
2781 && single_succ (combo_bb
) == join_bb
);
2783 /* Remove the jump and cruft from the end of the COMBO block. */
2784 if (join_bb
!= EXIT_BLOCK_PTR
)
2785 tidy_fallthru_edge (single_succ_edge (combo_bb
));
2788 num_updated_if_blocks
++;
2791 /* Find a block ending in a simple IF condition and try to transform it
2792 in some way. When converting a multi-block condition, put the new code
2793 in the first such block and delete the rest. Return a pointer to this
2794 first block if some transformation was done. Return NULL otherwise. */
2797 find_if_header (basic_block test_bb
, int pass
)
2799 ce_if_block_t ce_info
;
2803 /* The kind of block we're looking for has exactly two successors. */
2804 if (EDGE_COUNT (test_bb
->succs
) != 2)
2807 then_edge
= EDGE_SUCC (test_bb
, 0);
2808 else_edge
= EDGE_SUCC (test_bb
, 1);
2810 /* Neither edge should be abnormal. */
2811 if ((then_edge
->flags
& EDGE_COMPLEX
)
2812 || (else_edge
->flags
& EDGE_COMPLEX
))
2815 /* Nor exit the loop. */
2816 if ((then_edge
->flags
& EDGE_LOOP_EXIT
)
2817 || (else_edge
->flags
& EDGE_LOOP_EXIT
))
2820 /* The THEN edge is canonically the one that falls through. */
2821 if (then_edge
->flags
& EDGE_FALLTHRU
)
2823 else if (else_edge
->flags
& EDGE_FALLTHRU
)
2826 else_edge
= then_edge
;
2830 /* Otherwise this must be a multiway branch of some sort. */
2833 memset (&ce_info
, '\0', sizeof (ce_info
));
2834 ce_info
.test_bb
= test_bb
;
2835 ce_info
.then_bb
= then_edge
->dest
;
2836 ce_info
.else_bb
= else_edge
->dest
;
2837 ce_info
.pass
= pass
;
2839 #ifdef IFCVT_INIT_EXTRA_FIELDS
2840 IFCVT_INIT_EXTRA_FIELDS (&ce_info
);
2843 if (find_if_block (&ce_info
))
2846 if (HAVE_trap
&& HAVE_conditional_trap
2847 && find_cond_trap (test_bb
, then_edge
, else_edge
))
2850 if (dom_computed
[CDI_POST_DOMINATORS
] >= DOM_NO_FAST_QUERY
2851 && (! HAVE_conditional_execution
|| reload_completed
))
2853 if (find_if_case_1 (test_bb
, then_edge
, else_edge
))
2855 if (find_if_case_2 (test_bb
, then_edge
, else_edge
))
2863 fprintf (dump_file
, "Conversion succeeded on pass %d.\n", pass
);
2864 return ce_info
.test_bb
;
2867 /* Return true if a block has two edges, one of which falls through to the next
2868 block, and the other jumps to a specific block, so that we can tell if the
2869 block is part of an && test or an || test. Returns either -1 or the number
2870 of non-note, non-jump, non-USE/CLOBBER insns in the block. */
2873 block_jumps_and_fallthru_p (basic_block cur_bb
, basic_block target_bb
)
2876 int fallthru_p
= FALSE
;
2883 if (!cur_bb
|| !target_bb
)
2886 /* If no edges, obviously it doesn't jump or fallthru. */
2887 if (EDGE_COUNT (cur_bb
->succs
) == 0)
2890 FOR_EACH_EDGE (cur_edge
, ei
, cur_bb
->succs
)
2892 if (cur_edge
->flags
& EDGE_COMPLEX
)
2893 /* Anything complex isn't what we want. */
2896 else if (cur_edge
->flags
& EDGE_FALLTHRU
)
2899 else if (cur_edge
->dest
== target_bb
)
2906 if ((jump_p
& fallthru_p
) == 0)
2909 /* Don't allow calls in the block, since this is used to group && and ||
2910 together for conditional execution support. ??? we should support
2911 conditional execution support across calls for IA-64 some day, but
2912 for now it makes the code simpler. */
2913 end
= BB_END (cur_bb
);
2914 insn
= BB_HEAD (cur_bb
);
2916 while (insn
!= NULL_RTX
)
2923 && GET_CODE (PATTERN (insn
)) != USE
2924 && GET_CODE (PATTERN (insn
)) != CLOBBER
)
2930 insn
= NEXT_INSN (insn
);
2936 /* Determine if a given basic block heads a simple IF-THEN or IF-THEN-ELSE
2937 block. If so, we'll try to convert the insns to not require the branch.
2938 Return TRUE if we were successful at converting the block. */
2941 find_if_block (struct ce_if_block
* ce_info
)
2943 basic_block test_bb
= ce_info
->test_bb
;
2944 basic_block then_bb
= ce_info
->then_bb
;
2945 basic_block else_bb
= ce_info
->else_bb
;
2946 basic_block join_bb
= NULL_BLOCK
;
2951 ce_info
->last_test_bb
= test_bb
;
2953 /* Discover if any fall through predecessors of the current test basic block
2954 were && tests (which jump to the else block) or || tests (which jump to
2956 if (HAVE_conditional_execution
&& reload_completed
2957 && single_pred_p (test_bb
)
2958 && single_pred_edge (test_bb
)->flags
== EDGE_FALLTHRU
)
2960 basic_block bb
= single_pred (test_bb
);
2961 basic_block target_bb
;
2962 int max_insns
= MAX_CONDITIONAL_EXECUTE
;
2965 /* Determine if the preceding block is an && or || block. */
2966 if ((n_insns
= block_jumps_and_fallthru_p (bb
, else_bb
)) >= 0)
2968 ce_info
->and_and_p
= TRUE
;
2969 target_bb
= else_bb
;
2971 else if ((n_insns
= block_jumps_and_fallthru_p (bb
, then_bb
)) >= 0)
2973 ce_info
->and_and_p
= FALSE
;
2974 target_bb
= then_bb
;
2977 target_bb
= NULL_BLOCK
;
2979 if (target_bb
&& n_insns
<= max_insns
)
2981 int total_insns
= 0;
2984 ce_info
->last_test_bb
= test_bb
;
2986 /* Found at least one && or || block, look for more. */
2989 ce_info
->test_bb
= test_bb
= bb
;
2990 total_insns
+= n_insns
;
2993 if (!single_pred_p (bb
))
2996 bb
= single_pred (bb
);
2997 n_insns
= block_jumps_and_fallthru_p (bb
, target_bb
);
2999 while (n_insns
>= 0 && (total_insns
+ n_insns
) <= max_insns
);
3001 ce_info
->num_multiple_test_blocks
= blocks
;
3002 ce_info
->num_multiple_test_insns
= total_insns
;
3004 if (ce_info
->and_and_p
)
3005 ce_info
->num_and_and_blocks
= blocks
;
3007 ce_info
->num_or_or_blocks
= blocks
;
3011 /* The THEN block of an IF-THEN combo must have exactly one predecessor,
3012 other than any || blocks which jump to the THEN block. */
3013 if ((EDGE_COUNT (then_bb
->preds
) - ce_info
->num_or_or_blocks
) != 1)
3016 /* The edges of the THEN and ELSE blocks cannot have complex edges. */
3017 FOR_EACH_EDGE (cur_edge
, ei
, then_bb
->preds
)
3019 if (cur_edge
->flags
& EDGE_COMPLEX
)
3023 FOR_EACH_EDGE (cur_edge
, ei
, else_bb
->preds
)
3025 if (cur_edge
->flags
& EDGE_COMPLEX
)
3029 /* The THEN block of an IF-THEN combo must have zero or one successors. */
3030 if (EDGE_COUNT (then_bb
->succs
) > 0
3031 && (!single_succ_p (then_bb
)
3032 || (single_succ_edge (then_bb
)->flags
& EDGE_COMPLEX
)
3033 || (flow2_completed
&& tablejump_p (BB_END (then_bb
), NULL
, NULL
))))
3036 /* If the THEN block has no successors, conditional execution can still
3037 make a conditional call. Don't do this unless the ELSE block has
3038 only one incoming edge -- the CFG manipulation is too ugly otherwise.
3039 Check for the last insn of the THEN block being an indirect jump, which
3040 is listed as not having any successors, but confuses the rest of the CE
3041 code processing. ??? we should fix this in the future. */
3042 if (EDGE_COUNT (then_bb
->succs
) == 0)
3044 if (single_pred_p (else_bb
))
3046 rtx last_insn
= BB_END (then_bb
);
3049 && NOTE_P (last_insn
)
3050 && last_insn
!= BB_HEAD (then_bb
))
3051 last_insn
= PREV_INSN (last_insn
);
3054 && JUMP_P (last_insn
)
3055 && ! simplejump_p (last_insn
))
3059 else_bb
= NULL_BLOCK
;
3065 /* If the THEN block's successor is the other edge out of the TEST block,
3066 then we have an IF-THEN combo without an ELSE. */
3067 else if (single_succ (then_bb
) == else_bb
)
3070 else_bb
= NULL_BLOCK
;
3073 /* If the THEN and ELSE block meet in a subsequent block, and the ELSE
3074 has exactly one predecessor and one successor, and the outgoing edge
3075 is not complex, then we have an IF-THEN-ELSE combo. */
3076 else if (single_succ_p (else_bb
)
3077 && single_succ (then_bb
) == single_succ (else_bb
)
3078 && single_pred_p (else_bb
)
3079 && ! (single_succ_edge (else_bb
)->flags
& EDGE_COMPLEX
)
3080 && ! (flow2_completed
&& tablejump_p (BB_END (else_bb
), NULL
, NULL
)))
3081 join_bb
= single_succ (else_bb
);
3083 /* Otherwise it is not an IF-THEN or IF-THEN-ELSE combination. */
3087 num_possible_if_blocks
++;
3092 "\nIF-THEN%s block found, pass %d, start block %d "
3093 "[insn %d], then %d [%d]",
3094 (else_bb
) ? "-ELSE" : "",
3097 BB_HEAD (test_bb
) ? (int)INSN_UID (BB_HEAD (test_bb
)) : -1,
3099 BB_HEAD (then_bb
) ? (int)INSN_UID (BB_HEAD (then_bb
)) : -1);
3102 fprintf (dump_file
, ", else %d [%d]",
3104 BB_HEAD (else_bb
) ? (int)INSN_UID (BB_HEAD (else_bb
)) : -1);
3106 fprintf (dump_file
, ", join %d [%d]",
3108 BB_HEAD (join_bb
) ? (int)INSN_UID (BB_HEAD (join_bb
)) : -1);
3110 if (ce_info
->num_multiple_test_blocks
> 0)
3111 fprintf (dump_file
, ", %d %s block%s last test %d [%d]",
3112 ce_info
->num_multiple_test_blocks
,
3113 (ce_info
->and_and_p
) ? "&&" : "||",
3114 (ce_info
->num_multiple_test_blocks
== 1) ? "" : "s",
3115 ce_info
->last_test_bb
->index
,
3116 ((BB_HEAD (ce_info
->last_test_bb
))
3117 ? (int)INSN_UID (BB_HEAD (ce_info
->last_test_bb
))
3120 fputc ('\n', dump_file
);
3123 /* Make sure IF, THEN, and ELSE, blocks are adjacent. Actually, we get the
3124 first condition for free, since we've already asserted that there's a
3125 fallthru edge from IF to THEN. Likewise for the && and || blocks, since
3126 we checked the FALLTHRU flag, those are already adjacent to the last IF
3128 /* ??? As an enhancement, move the ELSE block. Have to deal with
3129 BLOCK notes, if by no other means than backing out the merge if they
3130 exist. Sticky enough I don't want to think about it now. */
3132 if (else_bb
&& (next
= next
->next_bb
) != else_bb
)
3134 if ((next
= next
->next_bb
) != join_bb
&& join_bb
!= EXIT_BLOCK_PTR
)
3142 /* Do the real work. */
3143 ce_info
->else_bb
= else_bb
;
3144 ce_info
->join_bb
= join_bb
;
3146 return process_if_block (ce_info
);
3149 /* Convert a branch over a trap, or a branch
3150 to a trap, into a conditional trap. */
3153 find_cond_trap (basic_block test_bb
, edge then_edge
, edge else_edge
)
3155 basic_block then_bb
= then_edge
->dest
;
3156 basic_block else_bb
= else_edge
->dest
;
3157 basic_block other_bb
, trap_bb
;
3158 rtx trap
, jump
, cond
, cond_earliest
, seq
;
3161 /* Locate the block with the trap instruction. */
3162 /* ??? While we look for no successors, we really ought to allow
3163 EH successors. Need to fix merge_if_block for that to work. */
3164 if ((trap
= block_has_only_trap (then_bb
)) != NULL
)
3165 trap_bb
= then_bb
, other_bb
= else_bb
;
3166 else if ((trap
= block_has_only_trap (else_bb
)) != NULL
)
3167 trap_bb
= else_bb
, other_bb
= then_bb
;
3173 fprintf (dump_file
, "\nTRAP-IF block found, start %d, trap %d\n",
3174 test_bb
->index
, trap_bb
->index
);
3177 /* If this is not a standard conditional jump, we can't parse it. */
3178 jump
= BB_END (test_bb
);
3179 cond
= noce_get_condition (jump
, &cond_earliest
);
3183 /* If the conditional jump is more than just a conditional jump, then
3184 we can not do if-conversion on this block. */
3185 if (! onlyjump_p (jump
))
3188 /* We must be comparing objects whose modes imply the size. */
3189 if (GET_MODE (XEXP (cond
, 0)) == BLKmode
)
3192 /* Reverse the comparison code, if necessary. */
3193 code
= GET_CODE (cond
);
3194 if (then_bb
== trap_bb
)
3196 code
= reversed_comparison_code (cond
, jump
);
3197 if (code
== UNKNOWN
)
3201 /* Attempt to generate the conditional trap. */
3202 seq
= gen_cond_trap (code
, XEXP (cond
, 0),
3204 TRAP_CODE (PATTERN (trap
)));
3210 /* Emit the new insns before cond_earliest. */
3211 emit_insn_before_setloc (seq
, cond_earliest
, INSN_LOCATOR (trap
));
3213 /* Delete the trap block if possible. */
3214 remove_edge (trap_bb
== then_bb
? then_edge
: else_edge
);
3215 if (EDGE_COUNT (trap_bb
->preds
) == 0)
3216 delete_basic_block (trap_bb
);
3218 /* If the non-trap block and the test are now adjacent, merge them.
3219 Otherwise we must insert a direct branch. */
3220 if (test_bb
->next_bb
== other_bb
)
3222 struct ce_if_block new_ce_info
;
3224 memset (&new_ce_info
, '\0', sizeof (new_ce_info
));
3225 new_ce_info
.test_bb
= test_bb
;
3226 new_ce_info
.then_bb
= NULL
;
3227 new_ce_info
.else_bb
= NULL
;
3228 new_ce_info
.join_bb
= other_bb
;
3229 merge_if_block (&new_ce_info
);
3235 lab
= JUMP_LABEL (jump
);
3236 newjump
= emit_jump_insn_after (gen_jump (lab
), jump
);
3237 LABEL_NUSES (lab
) += 1;
3238 JUMP_LABEL (newjump
) = lab
;
3239 emit_barrier_after (newjump
);
3247 /* Subroutine of find_cond_trap: if BB contains only a trap insn,
3251 block_has_only_trap (basic_block bb
)
3255 /* We're not the exit block. */
3256 if (bb
== EXIT_BLOCK_PTR
)
3259 /* The block must have no successors. */
3260 if (EDGE_COUNT (bb
->succs
) > 0)
3263 /* The only instruction in the THEN block must be the trap. */
3264 trap
= first_active_insn (bb
);
3265 if (! (trap
== BB_END (bb
)
3266 && GET_CODE (PATTERN (trap
)) == TRAP_IF
3267 && TRAP_CONDITION (PATTERN (trap
)) == const_true_rtx
))
3273 /* Look for IF-THEN-ELSE cases in which one of THEN or ELSE is
3274 transformable, but not necessarily the other. There need be no
3277 Return TRUE if we were successful at converting the block.
3279 Cases we'd like to look at:
3282 if (test) goto over; // x not live
3290 if (! test) goto label;
3293 if (test) goto E; // x not live
3307 (3) // This one's really only interesting for targets that can do
3308 // multiway branching, e.g. IA-64 BBB bundles. For other targets
3309 // it results in multiple branches on a cache line, which often
3310 // does not sit well with predictors.
3312 if (test1) goto E; // predicted not taken
3328 (A) Don't do (2) if the branch is predicted against the block we're
3329 eliminating. Do it anyway if we can eliminate a branch; this requires
3330 that the sole successor of the eliminated block postdominate the other
3333 (B) With CE, on (3) we can steal from both sides of the if, creating
3342 Again, this is most useful if J postdominates.
3344 (C) CE substitutes for helpful life information.
3346 (D) These heuristics need a lot of work. */
3348 /* Tests for case 1 above. */
3351 find_if_case_1 (basic_block test_bb
, edge then_edge
, edge else_edge
)
3353 basic_block then_bb
= then_edge
->dest
;
3354 basic_block else_bb
= else_edge
->dest
, new_bb
;
3357 /* If we are partitioning hot/cold basic blocks, we don't want to
3358 mess up unconditional or indirect jumps that cross between hot
3361 Basic block partitioning may result in some jumps that appear to
3362 be optimizable (or blocks that appear to be mergeable), but which really
3363 must be left untouched (they are required to make it safely across
3364 partition boundaries). See the comments at the top of
3365 bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */
3367 if ((BB_END (then_bb
)
3368 && find_reg_note (BB_END (then_bb
), REG_CROSSING_JUMP
, NULL_RTX
))
3369 || (BB_END (test_bb
)
3370 && find_reg_note (BB_END (test_bb
), REG_CROSSING_JUMP
, NULL_RTX
))
3371 || (BB_END (else_bb
)
3372 && find_reg_note (BB_END (else_bb
), REG_CROSSING_JUMP
,
3376 /* THEN has one successor. */
3377 if (!single_succ_p (then_bb
))
3380 /* THEN does not fall through, but is not strange either. */
3381 if (single_succ_edge (then_bb
)->flags
& (EDGE_COMPLEX
| EDGE_FALLTHRU
))
3384 /* THEN has one predecessor. */
3385 if (!single_pred_p (then_bb
))
3388 /* THEN must do something. */
3389 if (forwarder_block_p (then_bb
))
3392 num_possible_if_blocks
++;
3395 "\nIF-CASE-1 found, start %d, then %d\n",
3396 test_bb
->index
, then_bb
->index
);
3398 /* THEN is small. */
3399 if (! cheap_bb_rtx_cost_p (then_bb
, COSTS_N_INSNS (BRANCH_COST
)))
3402 /* Registers set are dead, or are predicable. */
3403 if (! dead_or_predicable (test_bb
, then_bb
, else_bb
,
3404 single_succ (then_bb
), 1))
3407 /* Conversion went ok, including moving the insns and fixing up the
3408 jump. Adjust the CFG to match. */
3410 bitmap_ior (test_bb
->il
.rtl
->global_live_at_end
,
3411 else_bb
->il
.rtl
->global_live_at_start
,
3412 then_bb
->il
.rtl
->global_live_at_end
);
3415 /* We can avoid creating a new basic block if then_bb is immediately
3416 followed by else_bb, i.e. deleting then_bb allows test_bb to fall
3419 if (then_bb
->next_bb
== else_bb
3420 && then_bb
->prev_bb
== test_bb
3421 && else_bb
!= EXIT_BLOCK_PTR
)
3423 redirect_edge_succ (FALLTHRU_EDGE (test_bb
), else_bb
);
3427 new_bb
= redirect_edge_and_branch_force (FALLTHRU_EDGE (test_bb
),
3430 then_bb_index
= then_bb
->index
;
3431 delete_basic_block (then_bb
);
3433 /* Make rest of code believe that the newly created block is the THEN_BB
3434 block we removed. */
3437 new_bb
->index
= then_bb_index
;
3438 SET_BASIC_BLOCK (then_bb_index
, new_bb
);
3439 /* Since the fallthru edge was redirected from test_bb to new_bb,
3440 we need to ensure that new_bb is in the same partition as
3441 test bb (you can not fall through across section boundaries). */
3442 BB_COPY_PARTITION (new_bb
, test_bb
);
3444 /* We've possibly created jump to next insn, cleanup_cfg will solve that
3448 num_updated_if_blocks
++;
3453 /* Test for case 2 above. */
3456 find_if_case_2 (basic_block test_bb
, edge then_edge
, edge else_edge
)
3458 basic_block then_bb
= then_edge
->dest
;
3459 basic_block else_bb
= else_edge
->dest
;
3463 /* If we are partitioning hot/cold basic blocks, we don't want to
3464 mess up unconditional or indirect jumps that cross between hot
3467 Basic block partitioning may result in some jumps that appear to
3468 be optimizable (or blocks that appear to be mergeable), but which really
3469 must be left untouched (they are required to make it safely across
3470 partition boundaries). See the comments at the top of
3471 bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */
3473 if ((BB_END (then_bb
)
3474 && find_reg_note (BB_END (then_bb
), REG_CROSSING_JUMP
, NULL_RTX
))
3475 || (BB_END (test_bb
)
3476 && find_reg_note (BB_END (test_bb
), REG_CROSSING_JUMP
, NULL_RTX
))
3477 || (BB_END (else_bb
)
3478 && find_reg_note (BB_END (else_bb
), REG_CROSSING_JUMP
,
3482 /* ELSE has one successor. */
3483 if (!single_succ_p (else_bb
))
3486 else_succ
= single_succ_edge (else_bb
);
3488 /* ELSE outgoing edge is not complex. */
3489 if (else_succ
->flags
& EDGE_COMPLEX
)
3492 /* ELSE has one predecessor. */
3493 if (!single_pred_p (else_bb
))
3496 /* THEN is not EXIT. */
3497 if (then_bb
->index
< NUM_FIXED_BLOCKS
)
3500 /* ELSE is predicted or SUCC(ELSE) postdominates THEN. */
3501 note
= find_reg_note (BB_END (test_bb
), REG_BR_PROB
, NULL_RTX
);
3502 if (note
&& INTVAL (XEXP (note
, 0)) >= REG_BR_PROB_BASE
/ 2)
3504 else if (else_succ
->dest
->index
< NUM_FIXED_BLOCKS
3505 || dominated_by_p (CDI_POST_DOMINATORS
, then_bb
,
3511 num_possible_if_blocks
++;
3514 "\nIF-CASE-2 found, start %d, else %d\n",
3515 test_bb
->index
, else_bb
->index
);
3517 /* ELSE is small. */
3518 if (! cheap_bb_rtx_cost_p (else_bb
, COSTS_N_INSNS (BRANCH_COST
)))
3521 /* Registers set are dead, or are predicable. */
3522 if (! dead_or_predicable (test_bb
, else_bb
, then_bb
, else_succ
->dest
, 0))
3525 /* Conversion went ok, including moving the insns and fixing up the
3526 jump. Adjust the CFG to match. */
3528 bitmap_ior (test_bb
->il
.rtl
->global_live_at_end
,
3529 then_bb
->il
.rtl
->global_live_at_start
,
3530 else_bb
->il
.rtl
->global_live_at_end
);
3532 delete_basic_block (else_bb
);
3535 num_updated_if_blocks
++;
3537 /* ??? We may now fallthru from one of THEN's successors into a join
3538 block. Rerun cleanup_cfg? Examine things manually? Wait? */
3543 /* A subroutine of dead_or_predicable called through for_each_rtx.
3544 Return 1 if a memory is found. */
3547 find_memory (rtx
*px
, void *data ATTRIBUTE_UNUSED
)
3552 /* Used by the code above to perform the actual rtl transformations.
3553 Return TRUE if successful.
3555 TEST_BB is the block containing the conditional branch. MERGE_BB
3556 is the block containing the code to manipulate. NEW_DEST is the
3557 label TEST_BB should be branching to after the conversion.
3558 REVERSEP is true if the sense of the branch should be reversed. */
3561 dead_or_predicable (basic_block test_bb
, basic_block merge_bb
,
3562 basic_block other_bb
, basic_block new_dest
, int reversep
)
3564 rtx head
, end
, jump
, earliest
= NULL_RTX
, old_dest
, new_label
= NULL_RTX
;
3566 jump
= BB_END (test_bb
);
3568 /* Find the extent of the real code in the merge block. */
3569 head
= BB_HEAD (merge_bb
);
3570 end
= BB_END (merge_bb
);
3572 /* If merge_bb ends with a tablejump, predicating/moving insn's
3573 into test_bb and then deleting merge_bb will result in the jumptable
3574 that follows merge_bb being removed along with merge_bb and then we
3575 get an unresolved reference to the jumptable. */
3576 if (tablejump_p (end
, NULL
, NULL
))
3580 head
= NEXT_INSN (head
);
3585 head
= end
= NULL_RTX
;
3588 head
= NEXT_INSN (head
);
3595 head
= end
= NULL_RTX
;
3598 end
= PREV_INSN (end
);
3601 /* Disable handling dead code by conditional execution if the machine needs
3602 to do anything funny with the tests, etc. */
3603 #ifndef IFCVT_MODIFY_TESTS
3604 if (HAVE_conditional_execution
)
3606 /* In the conditional execution case, we have things easy. We know
3607 the condition is reversible. We don't have to check life info
3608 because we're going to conditionally execute the code anyway.
3609 All that's left is making sure the insns involved can actually
3614 cond
= cond_exec_get_condition (jump
);
3618 prob_val
= find_reg_note (jump
, REG_BR_PROB
, NULL_RTX
);
3620 prob_val
= XEXP (prob_val
, 0);
3624 enum rtx_code rev
= reversed_comparison_code (cond
, jump
);
3627 cond
= gen_rtx_fmt_ee (rev
, GET_MODE (cond
), XEXP (cond
, 0),
3630 prob_val
= GEN_INT (REG_BR_PROB_BASE
- INTVAL (prob_val
));
3633 if (! cond_exec_process_insns ((ce_if_block_t
*)0, head
, end
, cond
,
3642 /* In the non-conditional execution case, we have to verify that there
3643 are no trapping operations, no calls, no references to memory, and
3644 that any registers modified are dead at the branch site. */
3646 rtx insn
, cond
, prev
;
3647 regset merge_set
, tmp
, test_live
, test_set
;
3648 struct propagate_block_info
*pbi
;
3649 unsigned i
, fail
= 0;
3652 /* Check for no calls or trapping operations. */
3653 for (insn
= head
; ; insn
= NEXT_INSN (insn
))
3659 if (may_trap_p (PATTERN (insn
)))
3662 /* ??? Even non-trapping memories such as stack frame
3663 references must be avoided. For stores, we collect
3664 no lifetime info; for reads, we'd have to assert
3665 true_dependence false against every store in the
3667 if (for_each_rtx (&PATTERN (insn
), find_memory
, NULL
))
3674 if (! any_condjump_p (jump
))
3677 /* Find the extent of the conditional. */
3678 cond
= noce_get_condition (jump
, &earliest
);
3683 MERGE_SET = set of registers set in MERGE_BB
3684 TEST_LIVE = set of registers live at EARLIEST
3685 TEST_SET = set of registers set between EARLIEST and the
3686 end of the block. */
3688 tmp
= ALLOC_REG_SET (®_obstack
);
3689 merge_set
= ALLOC_REG_SET (®_obstack
);
3690 test_live
= ALLOC_REG_SET (®_obstack
);
3691 test_set
= ALLOC_REG_SET (®_obstack
);
3693 /* ??? bb->local_set is only valid during calculate_global_regs_live,
3694 so we must recompute usage for MERGE_BB. Not so bad, I suppose,
3695 since we've already asserted that MERGE_BB is small. */
3696 /* If we allocated new pseudos (e.g. in the conditional move
3697 expander called from noce_emit_cmove), we must resize the
3699 if (max_regno
< max_reg_num ())
3701 max_regno
= max_reg_num ();
3702 allocate_reg_info (max_regno
, FALSE
, FALSE
);
3704 propagate_block (merge_bb
, tmp
, merge_set
, merge_set
, 0);
3706 /* For small register class machines, don't lengthen lifetimes of
3707 hard registers before reload. */
3708 if (SMALL_REGISTER_CLASSES
&& ! reload_completed
)
3710 EXECUTE_IF_SET_IN_BITMAP (merge_set
, 0, i
, bi
)
3712 if (i
< FIRST_PSEUDO_REGISTER
3714 && ! global_regs
[i
])
3719 /* For TEST, we're interested in a range of insns, not a whole block.
3720 Moreover, we're interested in the insns live from OTHER_BB. */
3722 COPY_REG_SET (test_live
, other_bb
->il
.rtl
->global_live_at_start
);
3723 pbi
= init_propagate_block_info (test_bb
, test_live
, test_set
, test_set
,
3726 for (insn
= jump
; ; insn
= prev
)
3728 prev
= propagate_one_insn (pbi
, insn
);
3729 if (insn
== earliest
)
3733 free_propagate_block_info (pbi
);
3735 /* We can perform the transformation if
3736 MERGE_SET & (TEST_SET | TEST_LIVE)
3738 TEST_SET & merge_bb->il.rtl->global_live_at_start
3741 if (bitmap_intersect_p (test_set
, merge_set
)
3742 || bitmap_intersect_p (test_live
, merge_set
)
3743 || bitmap_intersect_p (test_set
,
3744 merge_bb
->il
.rtl
->global_live_at_start
))
3748 FREE_REG_SET (merge_set
);
3749 FREE_REG_SET (test_live
);
3750 FREE_REG_SET (test_set
);
3757 /* We don't want to use normal invert_jump or redirect_jump because
3758 we don't want to delete_insn called. Also, we want to do our own
3759 change group management. */
3761 old_dest
= JUMP_LABEL (jump
);
3762 if (other_bb
!= new_dest
)
3764 new_label
= block_label (new_dest
);
3766 ? ! invert_jump_1 (jump
, new_label
)
3767 : ! redirect_jump_1 (jump
, new_label
))
3771 if (! apply_change_group ())
3774 if (other_bb
!= new_dest
)
3776 redirect_jump_2 (jump
, old_dest
, new_label
, -1, reversep
);
3778 redirect_edge_succ (BRANCH_EDGE (test_bb
), new_dest
);
3781 gcov_type count
, probability
;
3782 count
= BRANCH_EDGE (test_bb
)->count
;
3783 BRANCH_EDGE (test_bb
)->count
= FALLTHRU_EDGE (test_bb
)->count
;
3784 FALLTHRU_EDGE (test_bb
)->count
= count
;
3785 probability
= BRANCH_EDGE (test_bb
)->probability
;
3786 BRANCH_EDGE (test_bb
)->probability
3787 = FALLTHRU_EDGE (test_bb
)->probability
;
3788 FALLTHRU_EDGE (test_bb
)->probability
= probability
;
3789 update_br_prob_note (test_bb
);
3793 /* Move the insns out of MERGE_BB to before the branch. */
3798 if (end
== BB_END (merge_bb
))
3799 BB_END (merge_bb
) = PREV_INSN (head
);
3801 if (squeeze_notes (&head
, &end
))
3804 /* PR 21767: When moving insns above a conditional branch, REG_EQUAL
3805 notes might become invalid. */
3811 if (! INSN_P (insn
))
3813 note
= find_reg_note (insn
, REG_EQUAL
, NULL_RTX
);
3816 set
= single_set (insn
);
3817 if (!set
|| !function_invariant_p (SET_SRC (set
)))
3818 remove_note (insn
, note
);
3819 } while (insn
!= end
&& (insn
= NEXT_INSN (insn
)));
3821 reorder_insns (head
, end
, PREV_INSN (earliest
));
3824 /* Remove the jump and edge if we can. */
3825 if (other_bb
== new_dest
)
3828 remove_edge (BRANCH_EDGE (test_bb
));
3829 /* ??? Can't merge blocks here, as then_bb is still in use.
3830 At minimum, the merge will get done just before bb-reorder. */
3840 /* Main entry point for all if-conversion. */
3843 if_convert (int x_life_data_ok
)
3848 num_possible_if_blocks
= 0;
3849 num_updated_if_blocks
= 0;
3850 num_true_changes
= 0;
3851 life_data_ok
= (x_life_data_ok
!= 0);
3853 if ((! targetm
.cannot_modify_jumps_p ())
3854 && (!flag_reorder_blocks_and_partition
|| !no_new_pseudos
3855 || !targetm
.have_named_sections
))
3859 flow_loops_find (&loops
);
3860 mark_loop_exit_edges (&loops
);
3861 flow_loops_free (&loops
);
3862 free_dominance_info (CDI_DOMINATORS
);
3865 /* Compute postdominators if we think we'll use them. */
3866 if (HAVE_conditional_execution
|| life_data_ok
)
3867 calculate_dominance_info (CDI_POST_DOMINATORS
);
3872 /* Go through each of the basic blocks looking for things to convert. If we
3873 have conditional execution, we make multiple passes to allow us to handle
3874 IF-THEN{-ELSE} blocks within other IF-THEN{-ELSE} blocks. */
3878 cond_exec_changed_p
= FALSE
;
3881 #ifdef IFCVT_MULTIPLE_DUMPS
3882 if (dump_file
&& pass
> 1)
3883 fprintf (dump_file
, "\n\n========== Pass %d ==========\n", pass
);
3889 while ((new_bb
= find_if_header (bb
, pass
)))
3893 #ifdef IFCVT_MULTIPLE_DUMPS
3894 if (dump_file
&& cond_exec_changed_p
)
3895 print_rtl_with_bb (dump_file
, get_insns ());
3898 while (cond_exec_changed_p
);
3900 #ifdef IFCVT_MULTIPLE_DUMPS
3902 fprintf (dump_file
, "\n\n========== no more changes\n");
3905 free_dominance_info (CDI_POST_DOMINATORS
);
3910 clear_aux_for_blocks ();
3912 /* Rebuild life info for basic blocks that require it. */
3913 if (num_true_changes
&& life_data_ok
)
3915 /* If we allocated new pseudos, we must resize the array for sched1. */
3916 if (max_regno
< max_reg_num ())
3918 max_regno
= max_reg_num ();
3919 allocate_reg_info (max_regno
, FALSE
, FALSE
);
3921 update_life_info_in_dirty_blocks (UPDATE_LIFE_GLOBAL_RM_NOTES
,
3922 PROP_DEATH_NOTES
| PROP_SCAN_DEAD_CODE
3923 | PROP_KILL_DEAD_CODE
);
3926 /* Write the final stats. */
3927 if (dump_file
&& num_possible_if_blocks
> 0)
3930 "\n%d possible IF blocks searched.\n",
3931 num_possible_if_blocks
);
3933 "%d IF blocks converted.\n",
3934 num_updated_if_blocks
);
3936 "%d true changes made.\n\n\n",
3940 #ifdef ENABLE_CHECKING
3941 verify_flow_info ();
3946 gate_handle_if_conversion (void)
3948 return (optimize
> 0);
3951 /* If-conversion and CFG cleanup. */
3953 rest_of_handle_if_conversion (void)
3955 if (flag_if_conversion
)
3958 dump_flow_info (dump_file
, dump_flags
);
3959 cleanup_cfg (CLEANUP_EXPENSIVE
);
3960 reg_scan (get_insns (), max_reg_num ());
3964 timevar_push (TV_JUMP
);
3965 cleanup_cfg (CLEANUP_EXPENSIVE
);
3966 reg_scan (get_insns (), max_reg_num ());
3967 timevar_pop (TV_JUMP
);
3971 struct tree_opt_pass pass_rtl_ifcvt
=
3974 gate_handle_if_conversion
, /* gate */
3975 rest_of_handle_if_conversion
, /* execute */
3978 0, /* static_pass_number */
3979 TV_IFCVT
, /* tv_id */
3980 0, /* properties_required */
3981 0, /* properties_provided */
3982 0, /* properties_destroyed */
3983 0, /* todo_flags_start */
3984 TODO_dump_func
, /* todo_flags_finish */
3989 gate_handle_if_after_combine (void)
3991 return (optimize
> 0 && flag_if_conversion
);
3995 /* Rerun if-conversion, as combine may have simplified things enough
3996 to now meet sequence length restrictions. */
3998 rest_of_handle_if_after_combine (void)
4006 struct tree_opt_pass pass_if_after_combine
=
4009 gate_handle_if_after_combine
, /* gate */
4010 rest_of_handle_if_after_combine
, /* execute */
4013 0, /* static_pass_number */
4014 TV_IFCVT
, /* tv_id */
4015 0, /* properties_required */
4016 0, /* properties_provided */
4017 0, /* properties_destroyed */
4018 0, /* todo_flags_start */
4020 TODO_ggc_collect
, /* todo_flags_finish */
4026 gate_handle_if_after_reload (void)
4028 return (optimize
> 0);
4032 rest_of_handle_if_after_reload (void)
4034 /* Last attempt to optimize CFG, as scheduling, peepholing and insn
4035 splitting possibly introduced more crossjumping opportunities. */
4036 cleanup_cfg (CLEANUP_EXPENSIVE
4037 | CLEANUP_UPDATE_LIFE
4038 | (flag_crossjumping
? CLEANUP_CROSSJUMP
: 0));
4039 if (flag_if_conversion2
)
4045 struct tree_opt_pass pass_if_after_reload
=
4048 gate_handle_if_after_reload
, /* gate */
4049 rest_of_handle_if_after_reload
, /* execute */
4052 0, /* static_pass_number */
4053 TV_IFCVT2
, /* tv_id */
4054 0, /* properties_required */
4055 0, /* properties_provided */
4056 0, /* properties_destroyed */
4057 0, /* todo_flags_start */
4059 TODO_ggc_collect
, /* todo_flags_finish */