1 /* If-conversion support.
2 Copyright (C) 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007
3 Free Software Foundation, Inc.
5 This file is part of GCC.
7 GCC is free software; you can redistribute it and/or modify it
8 under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 3, 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 COPYING3. If not see
19 <http://www.gnu.org/licenses/>. */
23 #include "coretypes.h"
30 #include "insn-config.h"
33 #include "hard-reg-set.h"
34 #include "basic-block.h"
44 #include "tree-pass.h"
49 #ifndef HAVE_conditional_execution
50 #define HAVE_conditional_execution 0
52 #ifndef HAVE_conditional_move
53 #define HAVE_conditional_move 0
64 #ifndef HAVE_conditional_trap
65 #define HAVE_conditional_trap 0
68 #ifndef MAX_CONDITIONAL_EXECUTE
69 #define MAX_CONDITIONAL_EXECUTE (BRANCH_COST + 1)
72 #define IFCVT_MULTIPLE_DUMPS 1
74 #define NULL_BLOCK ((basic_block) NULL)
76 /* # of IF-THEN or IF-THEN-ELSE blocks we looked at */
77 static int num_possible_if_blocks
;
79 /* # of IF-THEN or IF-THEN-ELSE blocks were converted to conditional
81 static int num_updated_if_blocks
;
83 /* # of changes made. */
84 static int num_true_changes
;
86 /* Whether conditional execution changes were made. */
87 static int cond_exec_changed_p
;
89 /* Forward references. */
90 static int count_bb_insns (const_basic_block
);
91 static bool cheap_bb_rtx_cost_p (const_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 rtx
noce_get_condition (rtx
, rtx
*, bool);
98 static int noce_operand_ok (const_rtx
);
99 static void merge_if_block (ce_if_block_t
*);
100 static int find_cond_trap (basic_block
, edge
, edge
);
101 static basic_block
find_if_header (basic_block
, int);
102 static int block_jumps_and_fallthru_p (basic_block
, basic_block
);
103 static int noce_find_if_block (basic_block
, edge
, edge
, int);
104 static int cond_exec_find_if_block (ce_if_block_t
*);
105 static int find_if_case_1 (basic_block
, edge
, edge
);
106 static int find_if_case_2 (basic_block
, edge
, edge
);
107 static int find_memory (rtx
*, void *);
108 static int dead_or_predicable (basic_block
, basic_block
, basic_block
,
110 static void noce_emit_move_insn (rtx
, rtx
);
111 static rtx
block_has_only_trap (basic_block
);
113 /* Count the number of non-jump active insns in BB. */
116 count_bb_insns (const_basic_block bb
)
119 rtx insn
= BB_HEAD (bb
);
123 if (CALL_P (insn
) || NONJUMP_INSN_P (insn
))
126 if (insn
== BB_END (bb
))
128 insn
= NEXT_INSN (insn
);
134 /* Determine whether the total insn_rtx_cost on non-jump insns in
135 basic block BB is less than MAX_COST. This function returns
136 false if the cost of any instruction could not be estimated. */
139 cheap_bb_rtx_cost_p (const_basic_block bb
, int max_cost
)
142 rtx insn
= BB_HEAD (bb
);
146 if (NONJUMP_INSN_P (insn
))
148 int cost
= insn_rtx_cost (PATTERN (insn
));
152 /* If this instruction is the load or set of a "stack" register,
153 such as a floating point register on x87, then the cost of
154 speculatively executing this insn may need to include
155 the additional cost of popping its result off of the
156 register stack. Unfortunately, correctly recognizing and
157 accounting for this additional overhead is tricky, so for
158 now we simply prohibit such speculative execution. */
161 rtx set
= single_set (insn
);
162 if (set
&& STACK_REG_P (SET_DEST (set
)))
168 if (count
>= max_cost
)
171 else if (CALL_P (insn
))
174 if (insn
== BB_END (bb
))
176 insn
= NEXT_INSN (insn
);
182 /* Return the first non-jump active insn in the basic block. */
185 first_active_insn (basic_block bb
)
187 rtx insn
= BB_HEAD (bb
);
191 if (insn
== BB_END (bb
))
193 insn
= NEXT_INSN (insn
);
196 while (NOTE_P (insn
))
198 if (insn
== BB_END (bb
))
200 insn
= NEXT_INSN (insn
);
209 /* Return the last non-jump active (non-jump) insn in the basic block. */
212 last_active_insn (basic_block bb
, int skip_use_p
)
214 rtx insn
= BB_END (bb
);
215 rtx head
= BB_HEAD (bb
);
220 && NONJUMP_INSN_P (insn
)
221 && GET_CODE (PATTERN (insn
)) == USE
))
225 insn
= PREV_INSN (insn
);
234 /* Return the basic block reached by falling though the basic block BB. */
237 block_fallthru (basic_block bb
)
242 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
243 if (e
->flags
& EDGE_FALLTHRU
)
246 return (e
) ? e
->dest
: NULL_BLOCK
;
249 /* Go through a bunch of insns, converting them to conditional
250 execution format if possible. Return TRUE if all of the non-note
251 insns were processed. */
254 cond_exec_process_insns (ce_if_block_t
*ce_info ATTRIBUTE_UNUSED
,
255 /* if block information */rtx start
,
256 /* first insn to look at */rtx end
,
257 /* last insn to look at */rtx test
,
258 /* conditional execution test */rtx prob_val
,
259 /* probability of branch taken. */int mod_ok
)
261 int must_be_last
= FALSE
;
269 for (insn
= start
; ; insn
= NEXT_INSN (insn
))
274 gcc_assert(NONJUMP_INSN_P (insn
) || CALL_P (insn
));
276 /* Remove USE insns that get in the way. */
277 if (reload_completed
&& GET_CODE (PATTERN (insn
)) == USE
)
279 /* ??? Ug. Actually unlinking the thing is problematic,
280 given what we'd have to coordinate with our callers. */
281 SET_INSN_DELETED (insn
);
285 /* Last insn wasn't last? */
289 if (modified_in_p (test
, insn
))
296 /* Now build the conditional form of the instruction. */
297 pattern
= PATTERN (insn
);
298 xtest
= copy_rtx (test
);
300 /* If this is already a COND_EXEC, rewrite the test to be an AND of the
302 if (GET_CODE (pattern
) == COND_EXEC
)
304 if (GET_MODE (xtest
) != GET_MODE (COND_EXEC_TEST (pattern
)))
307 xtest
= gen_rtx_AND (GET_MODE (xtest
), xtest
,
308 COND_EXEC_TEST (pattern
));
309 pattern
= COND_EXEC_CODE (pattern
);
312 pattern
= gen_rtx_COND_EXEC (VOIDmode
, xtest
, pattern
);
314 /* If the machine needs to modify the insn being conditionally executed,
315 say for example to force a constant integer operand into a temp
316 register, do so here. */
317 #ifdef IFCVT_MODIFY_INSN
318 IFCVT_MODIFY_INSN (ce_info
, pattern
, insn
);
323 validate_change (insn
, &PATTERN (insn
), pattern
, 1);
325 if (CALL_P (insn
) && prob_val
)
326 validate_change (insn
, ®_NOTES (insn
),
327 alloc_EXPR_LIST (REG_BR_PROB
, prob_val
,
328 REG_NOTES (insn
)), 1);
338 /* Return the condition for a jump. Do not do any special processing. */
341 cond_exec_get_condition (rtx jump
)
345 if (any_condjump_p (jump
))
346 test_if
= SET_SRC (pc_set (jump
));
349 cond
= XEXP (test_if
, 0);
351 /* If this branches to JUMP_LABEL when the condition is false,
352 reverse the condition. */
353 if (GET_CODE (XEXP (test_if
, 2)) == LABEL_REF
354 && XEXP (XEXP (test_if
, 2), 0) == JUMP_LABEL (jump
))
356 enum rtx_code rev
= reversed_comparison_code (cond
, jump
);
360 cond
= gen_rtx_fmt_ee (rev
, GET_MODE (cond
), XEXP (cond
, 0),
367 /* Given a simple IF-THEN or IF-THEN-ELSE block, attempt to convert it
368 to conditional execution. Return TRUE if we were successful at
369 converting the block. */
372 cond_exec_process_if_block (ce_if_block_t
* ce_info
,
373 /* if block information */int do_multiple_p
)
375 basic_block test_bb
= ce_info
->test_bb
; /* last test block */
376 basic_block then_bb
= ce_info
->then_bb
; /* THEN */
377 basic_block else_bb
= ce_info
->else_bb
; /* ELSE or NULL */
378 rtx test_expr
; /* expression in IF_THEN_ELSE that is tested */
379 rtx then_start
; /* first insn in THEN block */
380 rtx then_end
; /* last insn + 1 in THEN block */
381 rtx else_start
= NULL_RTX
; /* first insn in ELSE block or NULL */
382 rtx else_end
= NULL_RTX
; /* last insn + 1 in ELSE block */
383 int max
; /* max # of insns to convert. */
384 int then_mod_ok
; /* whether conditional mods are ok in THEN */
385 rtx true_expr
; /* test for else block insns */
386 rtx false_expr
; /* test for then block insns */
387 rtx true_prob_val
; /* probability of else block */
388 rtx false_prob_val
; /* probability of then block */
390 enum rtx_code false_code
;
392 /* If test is comprised of && or || elements, and we've failed at handling
393 all of them together, just use the last test if it is the special case of
394 && elements without an ELSE block. */
395 if (!do_multiple_p
&& ce_info
->num_multiple_test_blocks
)
397 if (else_bb
|| ! ce_info
->and_and_p
)
400 ce_info
->test_bb
= test_bb
= ce_info
->last_test_bb
;
401 ce_info
->num_multiple_test_blocks
= 0;
402 ce_info
->num_and_and_blocks
= 0;
403 ce_info
->num_or_or_blocks
= 0;
406 /* Find the conditional jump to the ELSE or JOIN part, and isolate
408 test_expr
= cond_exec_get_condition (BB_END (test_bb
));
412 /* If the conditional jump is more than just a conditional jump,
413 then we can not do conditional execution conversion on this block. */
414 if (! onlyjump_p (BB_END (test_bb
)))
417 /* Collect the bounds of where we're to search, skipping any labels, jumps
418 and notes at the beginning and end of the block. Then count the total
419 number of insns and see if it is small enough to convert. */
420 then_start
= first_active_insn (then_bb
);
421 then_end
= last_active_insn (then_bb
, TRUE
);
422 n_insns
= ce_info
->num_then_insns
= count_bb_insns (then_bb
);
423 max
= MAX_CONDITIONAL_EXECUTE
;
428 else_start
= first_active_insn (else_bb
);
429 else_end
= last_active_insn (else_bb
, TRUE
);
430 n_insns
+= ce_info
->num_else_insns
= count_bb_insns (else_bb
);
436 /* Map test_expr/test_jump into the appropriate MD tests to use on
437 the conditionally executed code. */
439 true_expr
= test_expr
;
441 false_code
= reversed_comparison_code (true_expr
, BB_END (test_bb
));
442 if (false_code
!= UNKNOWN
)
443 false_expr
= gen_rtx_fmt_ee (false_code
, GET_MODE (true_expr
),
444 XEXP (true_expr
, 0), XEXP (true_expr
, 1));
446 false_expr
= NULL_RTX
;
448 #ifdef IFCVT_MODIFY_TESTS
449 /* If the machine description needs to modify the tests, such as setting a
450 conditional execution register from a comparison, it can do so here. */
451 IFCVT_MODIFY_TESTS (ce_info
, true_expr
, false_expr
);
453 /* See if the conversion failed. */
454 if (!true_expr
|| !false_expr
)
458 true_prob_val
= find_reg_note (BB_END (test_bb
), REG_BR_PROB
, NULL_RTX
);
461 true_prob_val
= XEXP (true_prob_val
, 0);
462 false_prob_val
= GEN_INT (REG_BR_PROB_BASE
- INTVAL (true_prob_val
));
465 false_prob_val
= NULL_RTX
;
467 /* If we have && or || tests, do them here. These tests are in the adjacent
468 blocks after the first block containing the test. */
469 if (ce_info
->num_multiple_test_blocks
> 0)
471 basic_block bb
= test_bb
;
472 basic_block last_test_bb
= ce_info
->last_test_bb
;
481 enum rtx_code f_code
;
483 bb
= block_fallthru (bb
);
484 start
= first_active_insn (bb
);
485 end
= last_active_insn (bb
, TRUE
);
487 && ! cond_exec_process_insns (ce_info
, start
, end
, false_expr
,
488 false_prob_val
, FALSE
))
491 /* If the conditional jump is more than just a conditional jump, then
492 we can not do conditional execution conversion on this block. */
493 if (! onlyjump_p (BB_END (bb
)))
496 /* Find the conditional jump and isolate the test. */
497 t
= cond_exec_get_condition (BB_END (bb
));
501 f_code
= reversed_comparison_code (t
, BB_END (bb
));
502 if (f_code
== UNKNOWN
)
505 f
= gen_rtx_fmt_ee (f_code
, GET_MODE (t
), XEXP (t
, 0), XEXP (t
, 1));
506 if (ce_info
->and_and_p
)
508 t
= gen_rtx_AND (GET_MODE (t
), true_expr
, t
);
509 f
= gen_rtx_IOR (GET_MODE (t
), false_expr
, f
);
513 t
= gen_rtx_IOR (GET_MODE (t
), true_expr
, t
);
514 f
= gen_rtx_AND (GET_MODE (t
), false_expr
, f
);
517 /* If the machine description needs to modify the tests, such as
518 setting a conditional execution register from a comparison, it can
520 #ifdef IFCVT_MODIFY_MULTIPLE_TESTS
521 IFCVT_MODIFY_MULTIPLE_TESTS (ce_info
, bb
, t
, f
);
523 /* See if the conversion failed. */
531 while (bb
!= last_test_bb
);
534 /* For IF-THEN-ELSE blocks, we don't allow modifications of the test
535 on then THEN block. */
536 then_mod_ok
= (else_bb
== NULL_BLOCK
);
538 /* Go through the THEN and ELSE blocks converting the insns if possible
539 to conditional execution. */
543 || ! cond_exec_process_insns (ce_info
, then_start
, then_end
,
544 false_expr
, false_prob_val
,
548 if (else_bb
&& else_end
549 && ! cond_exec_process_insns (ce_info
, else_start
, else_end
,
550 true_expr
, true_prob_val
, TRUE
))
553 /* If we cannot apply the changes, fail. Do not go through the normal fail
554 processing, since apply_change_group will call cancel_changes. */
555 if (! apply_change_group ())
557 #ifdef IFCVT_MODIFY_CANCEL
558 /* Cancel any machine dependent changes. */
559 IFCVT_MODIFY_CANCEL (ce_info
);
564 #ifdef IFCVT_MODIFY_FINAL
565 /* Do any machine dependent final modifications. */
566 IFCVT_MODIFY_FINAL (ce_info
);
569 /* Conversion succeeded. */
571 fprintf (dump_file
, "%d insn%s converted to conditional execution.\n",
572 n_insns
, (n_insns
== 1) ? " was" : "s were");
574 /* Merge the blocks! */
575 merge_if_block (ce_info
);
576 cond_exec_changed_p
= TRUE
;
580 #ifdef IFCVT_MODIFY_CANCEL
581 /* Cancel any machine dependent changes. */
582 IFCVT_MODIFY_CANCEL (ce_info
);
589 /* Used by noce_process_if_block to communicate with its subroutines.
591 The subroutines know that A and B may be evaluated freely. They
592 know that X is a register. They should insert new instructions
593 before cond_earliest. */
597 /* The basic blocks that make up the IF-THEN-{ELSE-,}JOIN block. */
598 basic_block test_bb
, then_bb
, else_bb
, join_bb
;
600 /* The jump that ends TEST_BB. */
603 /* The jump condition. */
606 /* New insns should be inserted before this one. */
609 /* Insns in the THEN and ELSE block. There is always just this
610 one insns in those blocks. The insns are single_set insns.
611 If there was no ELSE block, INSN_B is the last insn before
612 COND_EARLIEST, or NULL_RTX. In the former case, the insn
613 operands are still valid, as if INSN_B was moved down below
617 /* The SET_SRC of INSN_A and INSN_B. */
620 /* The SET_DEST of INSN_A. */
623 /* True if this if block is not canonical. In the canonical form of
624 if blocks, the THEN_BB is the block reached via the fallthru edge
625 from TEST_BB. For the noce transformations, we allow the symmetric
627 bool then_else_reversed
;
630 static rtx
noce_emit_store_flag (struct noce_if_info
*, rtx
, int, int);
631 static int noce_try_move (struct noce_if_info
*);
632 static int noce_try_store_flag (struct noce_if_info
*);
633 static int noce_try_addcc (struct noce_if_info
*);
634 static int noce_try_store_flag_constants (struct noce_if_info
*);
635 static int noce_try_store_flag_mask (struct noce_if_info
*);
636 static rtx
noce_emit_cmove (struct noce_if_info
*, rtx
, enum rtx_code
, rtx
,
638 static int noce_try_cmove (struct noce_if_info
*);
639 static int noce_try_cmove_arith (struct noce_if_info
*);
640 static rtx
noce_get_alt_condition (struct noce_if_info
*, rtx
, rtx
*);
641 static int noce_try_minmax (struct noce_if_info
*);
642 static int noce_try_abs (struct noce_if_info
*);
643 static int noce_try_sign_mask (struct noce_if_info
*);
645 /* Helper function for noce_try_store_flag*. */
648 noce_emit_store_flag (struct noce_if_info
*if_info
, rtx x
, int reversep
,
651 rtx cond
= if_info
->cond
;
655 cond_complex
= (! general_operand (XEXP (cond
, 0), VOIDmode
)
656 || ! general_operand (XEXP (cond
, 1), VOIDmode
));
658 /* If earliest == jump, or when the condition is complex, try to
659 build the store_flag insn directly. */
662 cond
= XEXP (SET_SRC (pc_set (if_info
->jump
)), 0);
665 code
= reversed_comparison_code (cond
, if_info
->jump
);
667 code
= GET_CODE (cond
);
669 if ((if_info
->cond_earliest
== if_info
->jump
|| cond_complex
)
670 && (normalize
== 0 || STORE_FLAG_VALUE
== normalize
))
674 tmp
= gen_rtx_fmt_ee (code
, GET_MODE (x
), XEXP (cond
, 0),
676 tmp
= gen_rtx_SET (VOIDmode
, x
, tmp
);
679 tmp
= emit_insn (tmp
);
681 if (recog_memoized (tmp
) >= 0)
687 if_info
->cond_earliest
= if_info
->jump
;
695 /* Don't even try if the comparison operands or the mode of X are weird. */
696 if (cond_complex
|| !SCALAR_INT_MODE_P (GET_MODE (x
)))
699 return emit_store_flag (x
, code
, XEXP (cond
, 0),
700 XEXP (cond
, 1), VOIDmode
,
701 (code
== LTU
|| code
== LEU
702 || code
== GEU
|| code
== GTU
), normalize
);
705 /* Emit instruction to move an rtx, possibly into STRICT_LOW_PART.
706 X is the destination/target and Y is the value to copy. */
709 noce_emit_move_insn (rtx x
, rtx y
)
711 enum machine_mode outmode
;
715 if (GET_CODE (x
) != STRICT_LOW_PART
)
717 rtx seq
, insn
, target
;
721 /* Check that the SET_SRC is reasonable before calling emit_move_insn,
722 otherwise construct a suitable SET pattern ourselves. */
723 insn
= (OBJECT_P (y
) || CONSTANT_P (y
) || GET_CODE (y
) == SUBREG
)
724 ? emit_move_insn (x
, y
)
725 : emit_insn (gen_rtx_SET (VOIDmode
, x
, y
));
729 if (recog_memoized (insn
) <= 0)
731 if (GET_CODE (x
) == ZERO_EXTRACT
)
733 rtx op
= XEXP (x
, 0);
734 unsigned HOST_WIDE_INT size
= INTVAL (XEXP (x
, 1));
735 unsigned HOST_WIDE_INT start
= INTVAL (XEXP (x
, 2));
737 /* store_bit_field expects START to be relative to
738 BYTES_BIG_ENDIAN and adjusts this value for machines with
739 BITS_BIG_ENDIAN != BYTES_BIG_ENDIAN. In order to be able to
740 invoke store_bit_field again it is necessary to have the START
741 value from the first call. */
742 if (BITS_BIG_ENDIAN
!= BYTES_BIG_ENDIAN
)
745 start
= BITS_PER_UNIT
- start
- size
;
748 gcc_assert (REG_P (op
));
749 start
= BITS_PER_WORD
- start
- size
;
753 gcc_assert (start
< (MEM_P (op
) ? BITS_PER_UNIT
: BITS_PER_WORD
));
754 store_bit_field (op
, size
, start
, GET_MODE (x
), y
);
758 switch (GET_RTX_CLASS (GET_CODE (y
)))
761 ot
= code_to_optab
[GET_CODE (y
)];
765 target
= expand_unop (GET_MODE (y
), ot
, XEXP (y
, 0), x
, 0);
766 if (target
!= NULL_RTX
)
769 emit_move_insn (x
, target
);
778 ot
= code_to_optab
[GET_CODE (y
)];
782 target
= expand_binop (GET_MODE (y
), ot
,
783 XEXP (y
, 0), XEXP (y
, 1),
785 if (target
!= NULL_RTX
)
788 emit_move_insn (x
, target
);
805 inner
= XEXP (outer
, 0);
806 outmode
= GET_MODE (outer
);
807 bitpos
= SUBREG_BYTE (outer
) * BITS_PER_UNIT
;
808 store_bit_field (inner
, GET_MODE_BITSIZE (outmode
), bitpos
, outmode
, y
);
811 /* Return sequence of instructions generated by if conversion. This
812 function calls end_sequence() to end the current stream, ensures
813 that are instructions are unshared, recognizable non-jump insns.
814 On failure, this function returns a NULL_RTX. */
817 end_ifcvt_sequence (struct noce_if_info
*if_info
)
820 rtx seq
= get_insns ();
822 set_used_flags (if_info
->x
);
823 set_used_flags (if_info
->cond
);
824 unshare_all_rtl_in_chain (seq
);
827 /* Make sure that all of the instructions emitted are recognizable,
828 and that we haven't introduced a new jump instruction.
829 As an exercise for the reader, build a general mechanism that
830 allows proper placement of required clobbers. */
831 for (insn
= seq
; insn
; insn
= NEXT_INSN (insn
))
833 || recog_memoized (insn
) == -1)
839 /* Convert "if (a != b) x = a; else x = b" into "x = a" and
840 "if (a == b) x = a; else x = b" into "x = b". */
843 noce_try_move (struct noce_if_info
*if_info
)
845 rtx cond
= if_info
->cond
;
846 enum rtx_code code
= GET_CODE (cond
);
849 if (code
!= NE
&& code
!= EQ
)
852 /* This optimization isn't valid if either A or B could be a NaN
854 if (HONOR_NANS (GET_MODE (if_info
->x
))
855 || HONOR_SIGNED_ZEROS (GET_MODE (if_info
->x
)))
858 /* Check whether the operands of the comparison are A and in
860 if ((rtx_equal_p (if_info
->a
, XEXP (cond
, 0))
861 && rtx_equal_p (if_info
->b
, XEXP (cond
, 1)))
862 || (rtx_equal_p (if_info
->a
, XEXP (cond
, 1))
863 && rtx_equal_p (if_info
->b
, XEXP (cond
, 0))))
865 y
= (code
== EQ
) ? if_info
->a
: if_info
->b
;
867 /* Avoid generating the move if the source is the destination. */
868 if (! rtx_equal_p (if_info
->x
, y
))
871 noce_emit_move_insn (if_info
->x
, y
);
872 seq
= end_ifcvt_sequence (if_info
);
876 emit_insn_before_setloc (seq
, if_info
->jump
,
877 INSN_LOCATOR (if_info
->insn_a
));
884 /* Convert "if (test) x = 1; else x = 0".
886 Only try 0 and STORE_FLAG_VALUE here. Other combinations will be
887 tried in noce_try_store_flag_constants after noce_try_cmove has had
888 a go at the conversion. */
891 noce_try_store_flag (struct noce_if_info
*if_info
)
896 if (GET_CODE (if_info
->b
) == CONST_INT
897 && INTVAL (if_info
->b
) == STORE_FLAG_VALUE
898 && if_info
->a
== const0_rtx
)
900 else if (if_info
->b
== const0_rtx
901 && GET_CODE (if_info
->a
) == CONST_INT
902 && INTVAL (if_info
->a
) == STORE_FLAG_VALUE
903 && (reversed_comparison_code (if_info
->cond
, if_info
->jump
)
911 target
= noce_emit_store_flag (if_info
, if_info
->x
, reversep
, 0);
914 if (target
!= if_info
->x
)
915 noce_emit_move_insn (if_info
->x
, target
);
917 seq
= end_ifcvt_sequence (if_info
);
921 emit_insn_before_setloc (seq
, if_info
->jump
,
922 INSN_LOCATOR (if_info
->insn_a
));
932 /* Convert "if (test) x = a; else x = b", for A and B constant. */
935 noce_try_store_flag_constants (struct noce_if_info
*if_info
)
939 HOST_WIDE_INT itrue
, ifalse
, diff
, tmp
;
940 int normalize
, can_reverse
;
941 enum machine_mode mode
;
943 if (GET_CODE (if_info
->a
) == CONST_INT
944 && GET_CODE (if_info
->b
) == CONST_INT
)
946 mode
= GET_MODE (if_info
->x
);
947 ifalse
= INTVAL (if_info
->a
);
948 itrue
= INTVAL (if_info
->b
);
950 /* Make sure we can represent the difference between the two values. */
951 if ((itrue
- ifalse
> 0)
952 != ((ifalse
< 0) != (itrue
< 0) ? ifalse
< 0 : ifalse
< itrue
))
955 diff
= trunc_int_for_mode (itrue
- ifalse
, mode
);
957 can_reverse
= (reversed_comparison_code (if_info
->cond
, if_info
->jump
)
961 if (diff
== STORE_FLAG_VALUE
|| diff
== -STORE_FLAG_VALUE
)
963 else if (ifalse
== 0 && exact_log2 (itrue
) >= 0
964 && (STORE_FLAG_VALUE
== 1
965 || BRANCH_COST
>= 2))
967 else if (itrue
== 0 && exact_log2 (ifalse
) >= 0 && can_reverse
968 && (STORE_FLAG_VALUE
== 1 || BRANCH_COST
>= 2))
969 normalize
= 1, reversep
= 1;
971 && (STORE_FLAG_VALUE
== -1
972 || BRANCH_COST
>= 2))
974 else if (ifalse
== -1 && can_reverse
975 && (STORE_FLAG_VALUE
== -1 || BRANCH_COST
>= 2))
976 normalize
= -1, reversep
= 1;
977 else if ((BRANCH_COST
>= 2 && STORE_FLAG_VALUE
== -1)
985 tmp
= itrue
; itrue
= ifalse
; ifalse
= tmp
;
986 diff
= trunc_int_for_mode (-diff
, mode
);
990 target
= noce_emit_store_flag (if_info
, if_info
->x
, reversep
, normalize
);
997 /* if (test) x = 3; else x = 4;
998 => x = 3 + (test == 0); */
999 if (diff
== STORE_FLAG_VALUE
|| diff
== -STORE_FLAG_VALUE
)
1001 target
= expand_simple_binop (mode
,
1002 (diff
== STORE_FLAG_VALUE
1004 GEN_INT (ifalse
), target
, if_info
->x
, 0,
1008 /* if (test) x = 8; else x = 0;
1009 => x = (test != 0) << 3; */
1010 else if (ifalse
== 0 && (tmp
= exact_log2 (itrue
)) >= 0)
1012 target
= expand_simple_binop (mode
, ASHIFT
,
1013 target
, GEN_INT (tmp
), if_info
->x
, 0,
1017 /* if (test) x = -1; else x = b;
1018 => x = -(test != 0) | b; */
1019 else if (itrue
== -1)
1021 target
= expand_simple_binop (mode
, IOR
,
1022 target
, GEN_INT (ifalse
), if_info
->x
, 0,
1026 /* if (test) x = a; else x = b;
1027 => x = (-(test != 0) & (b - a)) + a; */
1030 target
= expand_simple_binop (mode
, AND
,
1031 target
, GEN_INT (diff
), if_info
->x
, 0,
1034 target
= expand_simple_binop (mode
, PLUS
,
1035 target
, GEN_INT (ifalse
),
1036 if_info
->x
, 0, OPTAB_WIDEN
);
1045 if (target
!= if_info
->x
)
1046 noce_emit_move_insn (if_info
->x
, target
);
1048 seq
= end_ifcvt_sequence (if_info
);
1052 emit_insn_before_setloc (seq
, if_info
->jump
,
1053 INSN_LOCATOR (if_info
->insn_a
));
1060 /* Convert "if (test) foo++" into "foo += (test != 0)", and
1061 similarly for "foo--". */
1064 noce_try_addcc (struct noce_if_info
*if_info
)
1067 int subtract
, normalize
;
1069 if (GET_CODE (if_info
->a
) == PLUS
1070 && rtx_equal_p (XEXP (if_info
->a
, 0), if_info
->b
)
1071 && (reversed_comparison_code (if_info
->cond
, if_info
->jump
)
1074 rtx cond
= if_info
->cond
;
1075 enum rtx_code code
= reversed_comparison_code (cond
, if_info
->jump
);
1077 /* First try to use addcc pattern. */
1078 if (general_operand (XEXP (cond
, 0), VOIDmode
)
1079 && general_operand (XEXP (cond
, 1), VOIDmode
))
1082 target
= emit_conditional_add (if_info
->x
, code
,
1087 XEXP (if_info
->a
, 1),
1088 GET_MODE (if_info
->x
),
1089 (code
== LTU
|| code
== GEU
1090 || code
== LEU
|| code
== GTU
));
1093 if (target
!= if_info
->x
)
1094 noce_emit_move_insn (if_info
->x
, target
);
1096 seq
= end_ifcvt_sequence (if_info
);
1100 emit_insn_before_setloc (seq
, if_info
->jump
,
1101 INSN_LOCATOR (if_info
->insn_a
));
1107 /* If that fails, construct conditional increment or decrement using
1109 if (BRANCH_COST
>= 2
1110 && (XEXP (if_info
->a
, 1) == const1_rtx
1111 || XEXP (if_info
->a
, 1) == constm1_rtx
))
1114 if (STORE_FLAG_VALUE
== INTVAL (XEXP (if_info
->a
, 1)))
1115 subtract
= 0, normalize
= 0;
1116 else if (-STORE_FLAG_VALUE
== INTVAL (XEXP (if_info
->a
, 1)))
1117 subtract
= 1, normalize
= 0;
1119 subtract
= 0, normalize
= INTVAL (XEXP (if_info
->a
, 1));
1122 target
= noce_emit_store_flag (if_info
,
1123 gen_reg_rtx (GET_MODE (if_info
->x
)),
1127 target
= expand_simple_binop (GET_MODE (if_info
->x
),
1128 subtract
? MINUS
: PLUS
,
1129 if_info
->b
, target
, if_info
->x
,
1133 if (target
!= if_info
->x
)
1134 noce_emit_move_insn (if_info
->x
, target
);
1136 seq
= end_ifcvt_sequence (if_info
);
1140 emit_insn_before_setloc (seq
, if_info
->jump
,
1141 INSN_LOCATOR (if_info
->insn_a
));
1151 /* Convert "if (test) x = 0;" to "x &= -(test == 0);" */
1154 noce_try_store_flag_mask (struct noce_if_info
*if_info
)
1160 if ((BRANCH_COST
>= 2
1161 || STORE_FLAG_VALUE
== -1)
1162 && ((if_info
->a
== const0_rtx
1163 && rtx_equal_p (if_info
->b
, if_info
->x
))
1164 || ((reversep
= (reversed_comparison_code (if_info
->cond
,
1167 && if_info
->b
== const0_rtx
1168 && rtx_equal_p (if_info
->a
, if_info
->x
))))
1171 target
= noce_emit_store_flag (if_info
,
1172 gen_reg_rtx (GET_MODE (if_info
->x
)),
1175 target
= expand_simple_binop (GET_MODE (if_info
->x
), AND
,
1177 target
, if_info
->x
, 0,
1182 if (target
!= if_info
->x
)
1183 noce_emit_move_insn (if_info
->x
, target
);
1185 seq
= end_ifcvt_sequence (if_info
);
1189 emit_insn_before_setloc (seq
, if_info
->jump
,
1190 INSN_LOCATOR (if_info
->insn_a
));
1200 /* Helper function for noce_try_cmove and noce_try_cmove_arith. */
1203 noce_emit_cmove (struct noce_if_info
*if_info
, rtx x
, enum rtx_code code
,
1204 rtx cmp_a
, rtx cmp_b
, rtx vfalse
, rtx vtrue
)
1206 /* If earliest == jump, try to build the cmove insn directly.
1207 This is helpful when combine has created some complex condition
1208 (like for alpha's cmovlbs) that we can't hope to regenerate
1209 through the normal interface. */
1211 if (if_info
->cond_earliest
== if_info
->jump
)
1215 tmp
= gen_rtx_fmt_ee (code
, GET_MODE (if_info
->cond
), cmp_a
, cmp_b
);
1216 tmp
= gen_rtx_IF_THEN_ELSE (GET_MODE (x
), tmp
, vtrue
, vfalse
);
1217 tmp
= gen_rtx_SET (VOIDmode
, x
, tmp
);
1220 tmp
= emit_insn (tmp
);
1222 if (recog_memoized (tmp
) >= 0)
1234 /* Don't even try if the comparison operands are weird. */
1235 if (! general_operand (cmp_a
, GET_MODE (cmp_a
))
1236 || ! general_operand (cmp_b
, GET_MODE (cmp_b
)))
1239 #if HAVE_conditional_move
1240 return emit_conditional_move (x
, code
, cmp_a
, cmp_b
, VOIDmode
,
1241 vtrue
, vfalse
, GET_MODE (x
),
1242 (code
== LTU
|| code
== GEU
1243 || code
== LEU
|| code
== GTU
));
1245 /* We'll never get here, as noce_process_if_block doesn't call the
1246 functions involved. Ifdef code, however, should be discouraged
1247 because it leads to typos in the code not selected. However,
1248 emit_conditional_move won't exist either. */
1253 /* Try only simple constants and registers here. More complex cases
1254 are handled in noce_try_cmove_arith after noce_try_store_flag_arith
1255 has had a go at it. */
1258 noce_try_cmove (struct noce_if_info
*if_info
)
1263 if ((CONSTANT_P (if_info
->a
) || register_operand (if_info
->a
, VOIDmode
))
1264 && (CONSTANT_P (if_info
->b
) || register_operand (if_info
->b
, VOIDmode
)))
1268 code
= GET_CODE (if_info
->cond
);
1269 target
= noce_emit_cmove (if_info
, if_info
->x
, code
,
1270 XEXP (if_info
->cond
, 0),
1271 XEXP (if_info
->cond
, 1),
1272 if_info
->a
, if_info
->b
);
1276 if (target
!= if_info
->x
)
1277 noce_emit_move_insn (if_info
->x
, target
);
1279 seq
= end_ifcvt_sequence (if_info
);
1283 emit_insn_before_setloc (seq
, if_info
->jump
,
1284 INSN_LOCATOR (if_info
->insn_a
));
1297 /* Try more complex cases involving conditional_move. */
1300 noce_try_cmove_arith (struct noce_if_info
*if_info
)
1312 /* A conditional move from two memory sources is equivalent to a
1313 conditional on their addresses followed by a load. Don't do this
1314 early because it'll screw alias analysis. Note that we've
1315 already checked for no side effects. */
1316 /* ??? FIXME: Magic number 5. */
1317 if (cse_not_expected
1318 && MEM_P (a
) && MEM_P (b
)
1319 && BRANCH_COST
>= 5)
1323 x
= gen_reg_rtx (Pmode
);
1327 /* ??? We could handle this if we knew that a load from A or B could
1328 not fault. This is also true if we've already loaded
1329 from the address along the path from ENTRY. */
1330 else if (may_trap_p (a
) || may_trap_p (b
))
1333 /* if (test) x = a + b; else x = c - d;
1340 code
= GET_CODE (if_info
->cond
);
1341 insn_a
= if_info
->insn_a
;
1342 insn_b
= if_info
->insn_b
;
1344 /* Total insn_rtx_cost should be smaller than branch cost. Exit
1345 if insn_rtx_cost can't be estimated. */
1348 insn_cost
= insn_rtx_cost (PATTERN (insn_a
));
1349 if (insn_cost
== 0 || insn_cost
> COSTS_N_INSNS (BRANCH_COST
))
1357 insn_cost
+= insn_rtx_cost (PATTERN (insn_b
));
1358 if (insn_cost
== 0 || insn_cost
> COSTS_N_INSNS (BRANCH_COST
))
1362 /* Possibly rearrange operands to make things come out more natural. */
1363 if (reversed_comparison_code (if_info
->cond
, if_info
->jump
) != UNKNOWN
)
1366 if (rtx_equal_p (b
, x
))
1368 else if (general_operand (b
, GET_MODE (b
)))
1373 code
= reversed_comparison_code (if_info
->cond
, if_info
->jump
);
1374 tmp
= a
, a
= b
, b
= tmp
;
1375 tmp
= insn_a
, insn_a
= insn_b
, insn_b
= tmp
;
1384 /* If either operand is complex, load it into a register first.
1385 The best way to do this is to copy the original insn. In this
1386 way we preserve any clobbers etc that the insn may have had.
1387 This is of course not possible in the IS_MEM case. */
1388 if (! general_operand (a
, GET_MODE (a
)))
1394 tmp
= gen_reg_rtx (GET_MODE (a
));
1395 tmp
= emit_insn (gen_rtx_SET (VOIDmode
, tmp
, a
));
1398 goto end_seq_and_fail
;
1401 a
= gen_reg_rtx (GET_MODE (a
));
1402 tmp
= copy_rtx (insn_a
);
1403 set
= single_set (tmp
);
1405 tmp
= emit_insn (PATTERN (tmp
));
1407 if (recog_memoized (tmp
) < 0)
1408 goto end_seq_and_fail
;
1410 if (! general_operand (b
, GET_MODE (b
)))
1416 tmp
= gen_reg_rtx (GET_MODE (b
));
1417 tmp
= gen_rtx_SET (VOIDmode
, tmp
, b
);
1420 goto end_seq_and_fail
;
1423 b
= gen_reg_rtx (GET_MODE (b
));
1424 tmp
= copy_rtx (insn_b
);
1425 set
= single_set (tmp
);
1427 tmp
= PATTERN (tmp
);
1430 /* If insn to set up A clobbers any registers B depends on, try to
1431 swap insn that sets up A with the one that sets up B. If even
1432 that doesn't help, punt. */
1433 last
= get_last_insn ();
1434 if (last
&& modified_in_p (orig_b
, last
))
1436 tmp
= emit_insn_before (tmp
, get_insns ());
1437 if (modified_in_p (orig_a
, tmp
))
1438 goto end_seq_and_fail
;
1441 tmp
= emit_insn (tmp
);
1443 if (recog_memoized (tmp
) < 0)
1444 goto end_seq_and_fail
;
1447 target
= noce_emit_cmove (if_info
, x
, code
, XEXP (if_info
->cond
, 0),
1448 XEXP (if_info
->cond
, 1), a
, b
);
1451 goto end_seq_and_fail
;
1453 /* If we're handling a memory for above, emit the load now. */
1456 tmp
= gen_rtx_MEM (GET_MODE (if_info
->x
), target
);
1458 /* Copy over flags as appropriate. */
1459 if (MEM_VOLATILE_P (if_info
->a
) || MEM_VOLATILE_P (if_info
->b
))
1460 MEM_VOLATILE_P (tmp
) = 1;
1461 if (MEM_IN_STRUCT_P (if_info
->a
) && MEM_IN_STRUCT_P (if_info
->b
))
1462 MEM_IN_STRUCT_P (tmp
) = 1;
1463 if (MEM_SCALAR_P (if_info
->a
) && MEM_SCALAR_P (if_info
->b
))
1464 MEM_SCALAR_P (tmp
) = 1;
1465 if (MEM_ALIAS_SET (if_info
->a
) == MEM_ALIAS_SET (if_info
->b
))
1466 set_mem_alias_set (tmp
, MEM_ALIAS_SET (if_info
->a
));
1468 MIN (MEM_ALIGN (if_info
->a
), MEM_ALIGN (if_info
->b
)));
1470 noce_emit_move_insn (if_info
->x
, tmp
);
1472 else if (target
!= x
)
1473 noce_emit_move_insn (x
, target
);
1475 tmp
= end_ifcvt_sequence (if_info
);
1479 emit_insn_before_setloc (tmp
, if_info
->jump
, INSN_LOCATOR (if_info
->insn_a
));
1487 /* For most cases, the simplified condition we found is the best
1488 choice, but this is not the case for the min/max/abs transforms.
1489 For these we wish to know that it is A or B in the condition. */
1492 noce_get_alt_condition (struct noce_if_info
*if_info
, rtx target
,
1495 rtx cond
, set
, insn
;
1498 /* If target is already mentioned in the known condition, return it. */
1499 if (reg_mentioned_p (target
, if_info
->cond
))
1501 *earliest
= if_info
->cond_earliest
;
1502 return if_info
->cond
;
1505 set
= pc_set (if_info
->jump
);
1506 cond
= XEXP (SET_SRC (set
), 0);
1508 = GET_CODE (XEXP (SET_SRC (set
), 2)) == LABEL_REF
1509 && XEXP (XEXP (SET_SRC (set
), 2), 0) == JUMP_LABEL (if_info
->jump
);
1510 if (if_info
->then_else_reversed
)
1513 /* If we're looking for a constant, try to make the conditional
1514 have that constant in it. There are two reasons why it may
1515 not have the constant we want:
1517 1. GCC may have needed to put the constant in a register, because
1518 the target can't compare directly against that constant. For
1519 this case, we look for a SET immediately before the comparison
1520 that puts a constant in that register.
1522 2. GCC may have canonicalized the conditional, for example
1523 replacing "if x < 4" with "if x <= 3". We can undo that (or
1524 make equivalent types of changes) to get the constants we need
1525 if they're off by one in the right direction. */
1527 if (GET_CODE (target
) == CONST_INT
)
1529 enum rtx_code code
= GET_CODE (if_info
->cond
);
1530 rtx op_a
= XEXP (if_info
->cond
, 0);
1531 rtx op_b
= XEXP (if_info
->cond
, 1);
1534 /* First, look to see if we put a constant in a register. */
1535 prev_insn
= prev_nonnote_insn (if_info
->cond_earliest
);
1537 && BLOCK_NUM (prev_insn
) == BLOCK_NUM (if_info
->cond_earliest
)
1538 && INSN_P (prev_insn
)
1539 && GET_CODE (PATTERN (prev_insn
)) == SET
)
1541 rtx src
= find_reg_equal_equiv_note (prev_insn
);
1543 src
= SET_SRC (PATTERN (prev_insn
));
1544 if (GET_CODE (src
) == CONST_INT
)
1546 if (rtx_equal_p (op_a
, SET_DEST (PATTERN (prev_insn
))))
1548 else if (rtx_equal_p (op_b
, SET_DEST (PATTERN (prev_insn
))))
1551 if (GET_CODE (op_a
) == CONST_INT
)
1556 code
= swap_condition (code
);
1561 /* Now, look to see if we can get the right constant by
1562 adjusting the conditional. */
1563 if (GET_CODE (op_b
) == CONST_INT
)
1565 HOST_WIDE_INT desired_val
= INTVAL (target
);
1566 HOST_WIDE_INT actual_val
= INTVAL (op_b
);
1571 if (actual_val
== desired_val
+ 1)
1574 op_b
= GEN_INT (desired_val
);
1578 if (actual_val
== desired_val
- 1)
1581 op_b
= GEN_INT (desired_val
);
1585 if (actual_val
== desired_val
- 1)
1588 op_b
= GEN_INT (desired_val
);
1592 if (actual_val
== desired_val
+ 1)
1595 op_b
= GEN_INT (desired_val
);
1603 /* If we made any changes, generate a new conditional that is
1604 equivalent to what we started with, but has the right
1606 if (code
!= GET_CODE (if_info
->cond
)
1607 || op_a
!= XEXP (if_info
->cond
, 0)
1608 || op_b
!= XEXP (if_info
->cond
, 1))
1610 cond
= gen_rtx_fmt_ee (code
, GET_MODE (cond
), op_a
, op_b
);
1611 *earliest
= if_info
->cond_earliest
;
1616 cond
= canonicalize_condition (if_info
->jump
, cond
, reverse
,
1617 earliest
, target
, false, true);
1618 if (! cond
|| ! reg_mentioned_p (target
, cond
))
1621 /* We almost certainly searched back to a different place.
1622 Need to re-verify correct lifetimes. */
1624 /* X may not be mentioned in the range (cond_earliest, jump]. */
1625 for (insn
= if_info
->jump
; insn
!= *earliest
; insn
= PREV_INSN (insn
))
1626 if (INSN_P (insn
) && reg_overlap_mentioned_p (if_info
->x
, PATTERN (insn
)))
1629 /* A and B may not be modified in the range [cond_earliest, jump). */
1630 for (insn
= *earliest
; insn
!= if_info
->jump
; insn
= NEXT_INSN (insn
))
1632 && (modified_in_p (if_info
->a
, insn
)
1633 || modified_in_p (if_info
->b
, insn
)))
1639 /* Convert "if (a < b) x = a; else x = b;" to "x = min(a, b);", etc. */
1642 noce_try_minmax (struct noce_if_info
*if_info
)
1644 rtx cond
, earliest
, target
, seq
;
1645 enum rtx_code code
, op
;
1648 /* ??? Reject modes with NaNs or signed zeros since we don't know how
1649 they will be resolved with an SMIN/SMAX. It wouldn't be too hard
1650 to get the target to tell us... */
1651 if (HONOR_SIGNED_ZEROS (GET_MODE (if_info
->x
))
1652 || HONOR_NANS (GET_MODE (if_info
->x
)))
1655 cond
= noce_get_alt_condition (if_info
, if_info
->a
, &earliest
);
1659 /* Verify the condition is of the form we expect, and canonicalize
1660 the comparison code. */
1661 code
= GET_CODE (cond
);
1662 if (rtx_equal_p (XEXP (cond
, 0), if_info
->a
))
1664 if (! rtx_equal_p (XEXP (cond
, 1), if_info
->b
))
1667 else if (rtx_equal_p (XEXP (cond
, 1), if_info
->a
))
1669 if (! rtx_equal_p (XEXP (cond
, 0), if_info
->b
))
1671 code
= swap_condition (code
);
1676 /* Determine what sort of operation this is. Note that the code is for
1677 a taken branch, so the code->operation mapping appears backwards. */
1710 target
= expand_simple_binop (GET_MODE (if_info
->x
), op
,
1711 if_info
->a
, if_info
->b
,
1712 if_info
->x
, unsignedp
, OPTAB_WIDEN
);
1718 if (target
!= if_info
->x
)
1719 noce_emit_move_insn (if_info
->x
, target
);
1721 seq
= end_ifcvt_sequence (if_info
);
1725 emit_insn_before_setloc (seq
, if_info
->jump
, INSN_LOCATOR (if_info
->insn_a
));
1726 if_info
->cond
= cond
;
1727 if_info
->cond_earliest
= earliest
;
1732 /* Convert "if (a < 0) x = -a; else x = a;" to "x = abs(a);", etc. */
1735 noce_try_abs (struct noce_if_info
*if_info
)
1737 rtx cond
, earliest
, target
, seq
, a
, b
, c
;
1740 /* Recognize A and B as constituting an ABS or NABS. The canonical
1741 form is a branch around the negation, taken when the object is the
1742 first operand of a comparison against 0 that evaluates to true. */
1745 if (GET_CODE (a
) == NEG
&& rtx_equal_p (XEXP (a
, 0), b
))
1747 else if (GET_CODE (b
) == NEG
&& rtx_equal_p (XEXP (b
, 0), a
))
1749 c
= a
; a
= b
; b
= c
;
1755 cond
= noce_get_alt_condition (if_info
, b
, &earliest
);
1759 /* Verify the condition is of the form we expect. */
1760 if (rtx_equal_p (XEXP (cond
, 0), b
))
1762 else if (rtx_equal_p (XEXP (cond
, 1), b
))
1770 /* Verify that C is zero. Search one step backward for a
1771 REG_EQUAL note or a simple source if necessary. */
1774 rtx set
, insn
= prev_nonnote_insn (earliest
);
1776 && BLOCK_NUM (insn
) == BLOCK_NUM (earliest
)
1777 && (set
= single_set (insn
))
1778 && rtx_equal_p (SET_DEST (set
), c
))
1780 rtx note
= find_reg_equal_equiv_note (insn
);
1790 && GET_CODE (XEXP (c
, 0)) == SYMBOL_REF
1791 && CONSTANT_POOL_ADDRESS_P (XEXP (c
, 0)))
1792 c
= get_pool_constant (XEXP (c
, 0));
1794 /* Work around funny ideas get_condition has wrt canonicalization.
1795 Note that these rtx constants are known to be CONST_INT, and
1796 therefore imply integer comparisons. */
1797 if (c
== constm1_rtx
&& GET_CODE (cond
) == GT
)
1799 else if (c
== const1_rtx
&& GET_CODE (cond
) == LT
)
1801 else if (c
!= CONST0_RTX (GET_MODE (b
)))
1804 /* Determine what sort of operation this is. */
1805 switch (GET_CODE (cond
))
1824 target
= expand_abs_nojump (GET_MODE (if_info
->x
), b
, if_info
->x
, 1);
1826 /* ??? It's a quandary whether cmove would be better here, especially
1827 for integers. Perhaps combine will clean things up. */
1828 if (target
&& negate
)
1829 target
= expand_simple_unop (GET_MODE (target
), NEG
, target
, if_info
->x
, 0);
1837 if (target
!= if_info
->x
)
1838 noce_emit_move_insn (if_info
->x
, target
);
1840 seq
= end_ifcvt_sequence (if_info
);
1844 emit_insn_before_setloc (seq
, if_info
->jump
, INSN_LOCATOR (if_info
->insn_a
));
1845 if_info
->cond
= cond
;
1846 if_info
->cond_earliest
= earliest
;
1851 /* Convert "if (m < 0) x = b; else x = 0;" to "x = (m >> C) & b;". */
1854 noce_try_sign_mask (struct noce_if_info
*if_info
)
1856 rtx cond
, t
, m
, c
, seq
;
1857 enum machine_mode mode
;
1859 bool b_unconditional
;
1861 cond
= if_info
->cond
;
1862 code
= GET_CODE (cond
);
1867 if (if_info
->a
== const0_rtx
)
1869 if ((code
== LT
&& c
== const0_rtx
)
1870 || (code
== LE
&& c
== constm1_rtx
))
1873 else if (if_info
->b
== const0_rtx
)
1875 if ((code
== GE
&& c
== const0_rtx
)
1876 || (code
== GT
&& c
== constm1_rtx
))
1880 if (! t
|| side_effects_p (t
))
1883 /* We currently don't handle different modes. */
1884 mode
= GET_MODE (t
);
1885 if (GET_MODE (m
) != mode
)
1888 /* This is only profitable if T is cheap, or T is unconditionally
1889 executed/evaluated in the original insn sequence. The latter
1890 happens if INSN_B was taken from TEST_BB, or if there was no
1891 INSN_B which can happen for e.g. conditional stores to memory. */
1892 b_unconditional
= (if_info
->insn_b
== NULL_RTX
1893 || BLOCK_FOR_INSN (if_info
->insn_b
) == if_info
->test_bb
);
1894 if (rtx_cost (t
, SET
) >= COSTS_N_INSNS (2)
1895 && (!b_unconditional
1896 || t
!= if_info
->b
))
1900 /* Use emit_store_flag to generate "m < 0 ? -1 : 0" instead of expanding
1901 "(signed) m >> 31" directly. This benefits targets with specialized
1902 insns to obtain the signmask, but still uses ashr_optab otherwise. */
1903 m
= emit_store_flag (gen_reg_rtx (mode
), LT
, m
, const0_rtx
, mode
, 0, -1);
1904 t
= m
? expand_binop (mode
, and_optab
, m
, t
, NULL_RTX
, 0, OPTAB_DIRECT
)
1913 noce_emit_move_insn (if_info
->x
, t
);
1915 seq
= end_ifcvt_sequence (if_info
);
1919 emit_insn_before_setloc (seq
, if_info
->jump
, INSN_LOCATOR (if_info
->insn_a
));
1924 /* Optimize away "if (x & C) x |= C" and similar bit manipulation
1928 noce_try_bitop (struct noce_if_info
*if_info
)
1930 rtx cond
, x
, a
, result
, seq
;
1931 enum machine_mode mode
;
1936 cond
= if_info
->cond
;
1937 code
= GET_CODE (cond
);
1939 /* Check for no else condition. */
1940 if (! rtx_equal_p (x
, if_info
->b
))
1943 /* Check for a suitable condition. */
1944 if (code
!= NE
&& code
!= EQ
)
1946 if (XEXP (cond
, 1) != const0_rtx
)
1948 cond
= XEXP (cond
, 0);
1950 /* ??? We could also handle AND here. */
1951 if (GET_CODE (cond
) == ZERO_EXTRACT
)
1953 if (XEXP (cond
, 1) != const1_rtx
1954 || GET_CODE (XEXP (cond
, 2)) != CONST_INT
1955 || ! rtx_equal_p (x
, XEXP (cond
, 0)))
1957 bitnum
= INTVAL (XEXP (cond
, 2));
1958 mode
= GET_MODE (x
);
1959 if (BITS_BIG_ENDIAN
)
1960 bitnum
= GET_MODE_BITSIZE (mode
) - 1 - bitnum
;
1961 if (bitnum
< 0 || bitnum
>= HOST_BITS_PER_WIDE_INT
)
1968 if (GET_CODE (a
) == IOR
|| GET_CODE (a
) == XOR
)
1970 /* Check for "if (X & C) x = x op C". */
1971 if (! rtx_equal_p (x
, XEXP (a
, 0))
1972 || GET_CODE (XEXP (a
, 1)) != CONST_INT
1973 || (INTVAL (XEXP (a
, 1)) & GET_MODE_MASK (mode
))
1974 != (unsigned HOST_WIDE_INT
) 1 << bitnum
)
1977 /* if ((x & C) == 0) x |= C; is transformed to x |= C. */
1978 /* if ((x & C) != 0) x |= C; is transformed to nothing. */
1979 if (GET_CODE (a
) == IOR
)
1980 result
= (code
== NE
) ? a
: NULL_RTX
;
1981 else if (code
== NE
)
1983 /* if ((x & C) == 0) x ^= C; is transformed to x |= C. */
1984 result
= gen_int_mode ((HOST_WIDE_INT
) 1 << bitnum
, mode
);
1985 result
= simplify_gen_binary (IOR
, mode
, x
, result
);
1989 /* if ((x & C) != 0) x ^= C; is transformed to x &= ~C. */
1990 result
= gen_int_mode (~((HOST_WIDE_INT
) 1 << bitnum
), mode
);
1991 result
= simplify_gen_binary (AND
, mode
, x
, result
);
1994 else if (GET_CODE (a
) == AND
)
1996 /* Check for "if (X & C) x &= ~C". */
1997 if (! rtx_equal_p (x
, XEXP (a
, 0))
1998 || GET_CODE (XEXP (a
, 1)) != CONST_INT
1999 || (INTVAL (XEXP (a
, 1)) & GET_MODE_MASK (mode
))
2000 != (~((HOST_WIDE_INT
) 1 << bitnum
) & GET_MODE_MASK (mode
)))
2003 /* if ((x & C) == 0) x &= ~C; is transformed to nothing. */
2004 /* if ((x & C) != 0) x &= ~C; is transformed to x &= ~C. */
2005 result
= (code
== EQ
) ? a
: NULL_RTX
;
2013 noce_emit_move_insn (x
, result
);
2014 seq
= end_ifcvt_sequence (if_info
);
2018 emit_insn_before_setloc (seq
, if_info
->jump
,
2019 INSN_LOCATOR (if_info
->insn_a
));
2025 /* Similar to get_condition, only the resulting condition must be
2026 valid at JUMP, instead of at EARLIEST.
2028 If THEN_ELSE_REVERSED is true, the fallthrough does not go to the
2029 THEN block of the caller, and we have to reverse the condition. */
2032 noce_get_condition (rtx jump
, rtx
*earliest
, bool then_else_reversed
)
2037 if (! any_condjump_p (jump
))
2040 set
= pc_set (jump
);
2042 /* If this branches to JUMP_LABEL when the condition is false,
2043 reverse the condition. */
2044 reverse
= (GET_CODE (XEXP (SET_SRC (set
), 2)) == LABEL_REF
2045 && XEXP (XEXP (SET_SRC (set
), 2), 0) == JUMP_LABEL (jump
));
2047 /* We may have to reverse because the caller's if block is not canonical,
2048 i.e. the THEN block isn't the fallthrough block for the TEST block
2049 (see find_if_header). */
2050 if (then_else_reversed
)
2053 /* If the condition variable is a register and is MODE_INT, accept it. */
2055 cond
= XEXP (SET_SRC (set
), 0);
2056 tmp
= XEXP (cond
, 0);
2057 if (REG_P (tmp
) && GET_MODE_CLASS (GET_MODE (tmp
)) == MODE_INT
)
2062 cond
= gen_rtx_fmt_ee (reverse_condition (GET_CODE (cond
)),
2063 GET_MODE (cond
), tmp
, XEXP (cond
, 1));
2067 /* Otherwise, fall back on canonicalize_condition to do the dirty
2068 work of manipulating MODE_CC values and COMPARE rtx codes. */
2069 return canonicalize_condition (jump
, cond
, reverse
, earliest
,
2070 NULL_RTX
, false, true);
2073 /* Return true if OP is ok for if-then-else processing. */
2076 noce_operand_ok (const_rtx op
)
2078 /* We special-case memories, so handle any of them with
2079 no address side effects. */
2081 return ! side_effects_p (XEXP (op
, 0));
2083 if (side_effects_p (op
))
2086 return ! may_trap_p (op
);
2089 /* Return true if a write into MEM may trap or fault. */
2092 noce_mem_write_may_trap_or_fault_p (const_rtx mem
)
2096 if (MEM_READONLY_P (mem
))
2099 if (may_trap_or_fault_p (mem
))
2102 addr
= XEXP (mem
, 0);
2104 /* Call target hook to avoid the effects of -fpic etc.... */
2105 addr
= targetm
.delegitimize_address (addr
);
2108 switch (GET_CODE (addr
))
2116 addr
= XEXP (addr
, 0);
2120 addr
= XEXP (addr
, 1);
2123 if (GET_CODE (XEXP (addr
, 1)) == CONST_INT
)
2124 addr
= XEXP (addr
, 0);
2131 if (SYMBOL_REF_DECL (addr
)
2132 && decl_readonly_section (SYMBOL_REF_DECL (addr
), 0))
2142 /* Given a simple IF-THEN-JOIN or IF-THEN-ELSE-JOIN block, attempt to convert
2143 it without using conditional execution. Return TRUE if we were successful
2144 at converting the block. */
2147 noce_process_if_block (struct noce_if_info
*if_info
)
2149 basic_block test_bb
= if_info
->test_bb
; /* test block */
2150 basic_block then_bb
= if_info
->then_bb
; /* THEN */
2151 basic_block else_bb
= if_info
->else_bb
; /* ELSE or NULL */
2152 basic_block join_bb
= if_info
->join_bb
; /* JOIN */
2153 rtx jump
= if_info
->jump
;
2154 rtx cond
= if_info
->cond
;
2157 rtx orig_x
, x
, a
, b
;
2159 /* We're looking for patterns of the form
2161 (1) if (...) x = a; else x = b;
2162 (2) x = b; if (...) x = a;
2163 (3) if (...) x = a; // as if with an initial x = x.
2165 The later patterns require jumps to be more expensive.
2167 ??? For future expansion, look for multiple X in such patterns. */
2169 /* Look for one of the potential sets. */
2170 insn_a
= first_active_insn (then_bb
);
2172 || insn_a
!= last_active_insn (then_bb
, FALSE
)
2173 || (set_a
= single_set (insn_a
)) == NULL_RTX
)
2176 x
= SET_DEST (set_a
);
2177 a
= SET_SRC (set_a
);
2179 /* Look for the other potential set. Make sure we've got equivalent
2181 /* ??? This is overconservative. Storing to two different mems is
2182 as easy as conditionally computing the address. Storing to a
2183 single mem merely requires a scratch memory to use as one of the
2184 destination addresses; often the memory immediately below the
2185 stack pointer is available for this. */
2189 insn_b
= first_active_insn (else_bb
);
2191 || insn_b
!= last_active_insn (else_bb
, FALSE
)
2192 || (set_b
= single_set (insn_b
)) == NULL_RTX
2193 || ! rtx_equal_p (x
, SET_DEST (set_b
)))
2198 insn_b
= prev_nonnote_insn (if_info
->cond_earliest
);
2199 /* We're going to be moving the evaluation of B down from above
2200 COND_EARLIEST to JUMP. Make sure the relevant data is still
2203 || BLOCK_NUM (insn_b
) != BLOCK_NUM (if_info
->cond_earliest
)
2204 || !NONJUMP_INSN_P (insn_b
)
2205 || (set_b
= single_set (insn_b
)) == NULL_RTX
2206 || ! rtx_equal_p (x
, SET_DEST (set_b
))
2207 || reg_overlap_mentioned_p (x
, SET_SRC (set_b
))
2208 || modified_between_p (SET_SRC (set_b
),
2209 PREV_INSN (if_info
->cond_earliest
), jump
)
2210 /* Likewise with X. In particular this can happen when
2211 noce_get_condition looks farther back in the instruction
2212 stream than one might expect. */
2213 || reg_overlap_mentioned_p (x
, cond
)
2214 || reg_overlap_mentioned_p (x
, a
)
2215 || modified_between_p (x
, PREV_INSN (if_info
->cond_earliest
), jump
))
2216 insn_b
= set_b
= NULL_RTX
;
2219 /* If x has side effects then only the if-then-else form is safe to
2220 convert. But even in that case we would need to restore any notes
2221 (such as REG_INC) at then end. That can be tricky if
2222 noce_emit_move_insn expands to more than one insn, so disable the
2223 optimization entirely for now if there are side effects. */
2224 if (side_effects_p (x
))
2227 b
= (set_b
? SET_SRC (set_b
) : x
);
2229 /* Only operate on register destinations, and even then avoid extending
2230 the lifetime of hard registers on small register class machines. */
2233 || (SMALL_REGISTER_CLASSES
2234 && REGNO (x
) < FIRST_PSEUDO_REGISTER
))
2236 if (GET_MODE (x
) == BLKmode
)
2239 if (GET_MODE (x
) == ZERO_EXTRACT
2240 && (GET_CODE (XEXP (x
, 1)) != CONST_INT
2241 || GET_CODE (XEXP (x
, 2)) != CONST_INT
))
2244 x
= gen_reg_rtx (GET_MODE (GET_CODE (x
) == STRICT_LOW_PART
2245 ? XEXP (x
, 0) : x
));
2248 /* Don't operate on sources that may trap or are volatile. */
2249 if (! noce_operand_ok (a
) || ! noce_operand_ok (b
))
2252 /* Set up the info block for our subroutines. */
2253 if_info
->insn_a
= insn_a
;
2254 if_info
->insn_b
= insn_b
;
2259 /* Try optimizations in some approximation of a useful order. */
2260 /* ??? Should first look to see if X is live incoming at all. If it
2261 isn't, we don't need anything but an unconditional set. */
2263 /* Look and see if A and B are really the same. Avoid creating silly
2264 cmove constructs that no one will fix up later. */
2265 if (rtx_equal_p (a
, b
))
2267 /* If we have an INSN_B, we don't have to create any new rtl. Just
2268 move the instruction that we already have. If we don't have an
2269 INSN_B, that means that A == X, and we've got a noop move. In
2270 that case don't do anything and let the code below delete INSN_A. */
2271 if (insn_b
&& else_bb
)
2275 if (else_bb
&& insn_b
== BB_END (else_bb
))
2276 BB_END (else_bb
) = PREV_INSN (insn_b
);
2277 reorder_insns (insn_b
, insn_b
, PREV_INSN (jump
));
2279 /* If there was a REG_EQUAL note, delete it since it may have been
2280 true due to this insn being after a jump. */
2281 if ((note
= find_reg_note (insn_b
, REG_EQUAL
, NULL_RTX
)) != 0)
2282 remove_note (insn_b
, note
);
2286 /* If we have "x = b; if (...) x = a;", and x has side-effects, then
2287 x must be executed twice. */
2288 else if (insn_b
&& side_effects_p (orig_x
))
2295 /* Disallow the "if (...) x = a;" form (with an implicit "else x = x;")
2296 for optimizations if writing to x may trap or fault, i.e. it's a memory
2297 other than a static var or a stack slot, is misaligned on strict
2298 aligned machines or is read-only.
2299 If x is a read-only memory, then the program is valid only if we
2300 avoid the store into it. If there are stores on both the THEN and
2301 ELSE arms, then we can go ahead with the conversion; either the
2302 program is broken, or the condition is always false such that the
2303 other memory is selected. */
2304 if (!set_b
&& MEM_P (orig_x
) && noce_mem_write_may_trap_or_fault_p (orig_x
))
2307 if (noce_try_move (if_info
))
2309 if (noce_try_store_flag (if_info
))
2311 if (noce_try_bitop (if_info
))
2313 if (noce_try_minmax (if_info
))
2315 if (noce_try_abs (if_info
))
2317 if (HAVE_conditional_move
2318 && noce_try_cmove (if_info
))
2320 if (! HAVE_conditional_execution
)
2322 if (noce_try_store_flag_constants (if_info
))
2324 if (noce_try_addcc (if_info
))
2326 if (noce_try_store_flag_mask (if_info
))
2328 if (HAVE_conditional_move
2329 && noce_try_cmove_arith (if_info
))
2331 if (noce_try_sign_mask (if_info
))
2339 /* If we used a temporary, fix it up now. */
2345 noce_emit_move_insn (orig_x
, x
);
2347 set_used_flags (orig_x
);
2348 unshare_all_rtl_in_chain (seq
);
2351 emit_insn_before_setloc (seq
, BB_END (test_bb
), INSN_LOCATOR (insn_a
));
2354 /* The original THEN and ELSE blocks may now be removed. The test block
2355 must now jump to the join block. If the test block and the join block
2356 can be merged, do so. */
2359 delete_basic_block (else_bb
);
2363 remove_edge (find_edge (test_bb
, join_bb
));
2365 remove_edge (find_edge (then_bb
, join_bb
));
2366 redirect_edge_and_branch_force (single_succ_edge (test_bb
), join_bb
);
2367 delete_basic_block (then_bb
);
2370 if (can_merge_blocks_p (test_bb
, join_bb
))
2372 merge_blocks (test_bb
, join_bb
);
2376 num_updated_if_blocks
++;
2380 /* Check whether a block is suitable for conditional move conversion.
2381 Every insn must be a simple set of a register to a constant or a
2382 register. For each assignment, store the value in the array VALS,
2383 indexed by register number, then store the register number in
2384 REGS. COND is the condition we will test. */
2387 check_cond_move_block (basic_block bb
, rtx
*vals
, VEC (int, heap
) *regs
, rtx cond
)
2391 /* We can only handle simple jumps at the end of the basic block.
2392 It is almost impossible to update the CFG otherwise. */
2394 if (JUMP_P (insn
) && !onlyjump_p (insn
))
2397 FOR_BB_INSNS (bb
, insn
)
2401 if (!INSN_P (insn
) || JUMP_P (insn
))
2403 set
= single_set (insn
);
2407 dest
= SET_DEST (set
);
2408 src
= SET_SRC (set
);
2410 || (SMALL_REGISTER_CLASSES
&& HARD_REGISTER_P (dest
)))
2413 if (!CONSTANT_P (src
) && !register_operand (src
, VOIDmode
))
2416 if (side_effects_p (src
) || side_effects_p (dest
))
2419 if (may_trap_p (src
) || may_trap_p (dest
))
2422 /* Don't try to handle this if the source register was
2423 modified earlier in the block. */
2425 && vals
[REGNO (src
)] != NULL
)
2426 || (GET_CODE (src
) == SUBREG
&& REG_P (SUBREG_REG (src
))
2427 && vals
[REGNO (SUBREG_REG (src
))] != NULL
))
2430 /* Don't try to handle this if the destination register was
2431 modified earlier in the block. */
2432 if (vals
[REGNO (dest
)] != NULL
)
2435 /* Don't try to handle this if the condition uses the
2436 destination register. */
2437 if (reg_overlap_mentioned_p (dest
, cond
))
2440 /* Don't try to handle this if the source register is modified
2441 later in the block. */
2442 if (!CONSTANT_P (src
)
2443 && modified_between_p (src
, insn
, NEXT_INSN (BB_END (bb
))))
2446 vals
[REGNO (dest
)] = src
;
2448 VEC_safe_push (int, heap
, regs
, REGNO (dest
));
2454 /* Given a basic block BB suitable for conditional move conversion,
2455 a condition COND, and arrays THEN_VALS and ELSE_VALS containing the
2456 register values depending on COND, emit the insns in the block as
2457 conditional moves. If ELSE_BLOCK is true, THEN_BB was already
2458 processed. The caller has started a sequence for the conversion.
2459 Return true if successful, false if something goes wrong. */
2462 cond_move_convert_if_block (struct noce_if_info
*if_infop
,
2463 basic_block bb
, rtx cond
,
2464 rtx
*then_vals
, rtx
*else_vals
,
2468 rtx insn
, cond_arg0
, cond_arg1
;
2470 code
= GET_CODE (cond
);
2471 cond_arg0
= XEXP (cond
, 0);
2472 cond_arg1
= XEXP (cond
, 1);
2474 FOR_BB_INSNS (bb
, insn
)
2476 rtx set
, target
, dest
, t
, e
;
2479 if (!INSN_P (insn
) || JUMP_P (insn
))
2481 set
= single_set (insn
);
2482 gcc_assert (set
&& REG_P (SET_DEST (set
)));
2484 dest
= SET_DEST (set
);
2485 regno
= REGNO (dest
);
2487 t
= then_vals
[regno
];
2488 e
= else_vals
[regno
];
2492 /* If this register was set in the then block, we already
2493 handled this case there. */
2506 target
= noce_emit_cmove (if_infop
, dest
, code
, cond_arg0
, cond_arg1
,
2512 noce_emit_move_insn (dest
, target
);
2518 /* Given a simple IF-THEN-JOIN or IF-THEN-ELSE-JOIN block, attempt to convert
2519 it using only conditional moves. Return TRUE if we were successful at
2520 converting the block. */
2523 cond_move_process_if_block (struct noce_if_info
*if_info
)
2525 basic_block test_bb
= if_info
->test_bb
;
2526 basic_block then_bb
= if_info
->then_bb
;
2527 basic_block else_bb
= if_info
->else_bb
;
2528 basic_block join_bb
= if_info
->join_bb
;
2529 rtx jump
= if_info
->jump
;
2530 rtx cond
= if_info
->cond
;
2532 int max_reg
, size
, c
, reg
;
2535 VEC (int, heap
) *then_regs
= NULL
;
2536 VEC (int, heap
) *else_regs
= NULL
;
2539 /* Build a mapping for each block to the value used for each
2541 max_reg
= max_reg_num ();
2542 size
= (max_reg
+ 1) * sizeof (rtx
);
2543 then_vals
= (rtx
*) alloca (size
);
2544 else_vals
= (rtx
*) alloca (size
);
2545 memset (then_vals
, 0, size
);
2546 memset (else_vals
, 0, size
);
2548 /* Make sure the blocks are suitable. */
2549 if (!check_cond_move_block (then_bb
, then_vals
, then_regs
, cond
)
2550 || (else_bb
&& !check_cond_move_block (else_bb
, else_vals
, else_regs
, cond
)))
2553 /* Make sure the blocks can be used together. If the same register
2554 is set in both blocks, and is not set to a constant in both
2555 cases, then both blocks must set it to the same register. We
2556 have already verified that if it is set to a register, that the
2557 source register does not change after the assignment. Also count
2558 the number of registers set in only one of the blocks. */
2560 for (i
= 0; VEC_iterate (int, then_regs
, i
, reg
); i
++)
2562 if (!then_vals
[reg
] && !else_vals
[reg
])
2565 if (!else_vals
[reg
])
2569 if (!CONSTANT_P (then_vals
[reg
])
2570 && !CONSTANT_P (else_vals
[reg
])
2571 && !rtx_equal_p (then_vals
[reg
], else_vals
[reg
]))
2576 /* Finish off c for MAX_CONDITIONAL_EXECUTE. */
2577 for (i
= 0; VEC_iterate (int, else_regs
, i
, reg
); ++i
)
2578 if (!then_vals
[reg
])
2581 /* Make sure it is reasonable to convert this block. What matters
2582 is the number of assignments currently made in only one of the
2583 branches, since if we convert we are going to always execute
2585 if (c
> MAX_CONDITIONAL_EXECUTE
)
2588 /* Try to emit the conditional moves. First do the then block,
2589 then do anything left in the else blocks. */
2591 if (!cond_move_convert_if_block (if_info
, then_bb
, cond
,
2592 then_vals
, else_vals
, false)
2594 && !cond_move_convert_if_block (if_info
, else_bb
, cond
,
2595 then_vals
, else_vals
, true)))
2600 seq
= end_ifcvt_sequence (if_info
);
2604 loc_insn
= first_active_insn (then_bb
);
2607 loc_insn
= first_active_insn (else_bb
);
2608 gcc_assert (loc_insn
);
2610 emit_insn_before_setloc (seq
, jump
, INSN_LOCATOR (loc_insn
));
2614 delete_basic_block (else_bb
);
2618 remove_edge (find_edge (test_bb
, join_bb
));
2620 remove_edge (find_edge (then_bb
, join_bb
));
2621 redirect_edge_and_branch_force (single_succ_edge (test_bb
), join_bb
);
2622 delete_basic_block (then_bb
);
2625 if (can_merge_blocks_p (test_bb
, join_bb
))
2627 merge_blocks (test_bb
, join_bb
);
2631 num_updated_if_blocks
++;
2633 VEC_free (int, heap
, then_regs
);
2634 VEC_free (int, heap
, else_regs
);
2640 /* Determine if a given basic block heads a simple IF-THEN-JOIN or an
2641 IF-THEN-ELSE-JOIN block.
2643 If so, we'll try to convert the insns to not require the branch,
2644 using only transformations that do not require conditional execution.
2646 Return TRUE if we were successful at converting the block. */
2649 noce_find_if_block (basic_block test_bb
,
2650 edge then_edge
, edge else_edge
,
2653 basic_block then_bb
, else_bb
, join_bb
;
2654 bool then_else_reversed
= false;
2657 struct noce_if_info if_info
;
2659 /* We only ever should get here before reload. */
2660 gcc_assert (!reload_completed
);
2662 /* Recognize an IF-THEN-ELSE-JOIN block. */
2663 if (single_pred_p (then_edge
->dest
)
2664 && single_succ_p (then_edge
->dest
)
2665 && single_pred_p (else_edge
->dest
)
2666 && single_succ_p (else_edge
->dest
)
2667 && single_succ (then_edge
->dest
) == single_succ (else_edge
->dest
))
2669 then_bb
= then_edge
->dest
;
2670 else_bb
= else_edge
->dest
;
2671 join_bb
= single_succ (then_bb
);
2673 /* Recognize an IF-THEN-JOIN block. */
2674 else if (single_pred_p (then_edge
->dest
)
2675 && single_succ_p (then_edge
->dest
)
2676 && single_succ (then_edge
->dest
) == else_edge
->dest
)
2678 then_bb
= then_edge
->dest
;
2679 else_bb
= NULL_BLOCK
;
2680 join_bb
= else_edge
->dest
;
2682 /* Recognize an IF-ELSE-JOIN block. We can have those because the order
2683 of basic blocks in cfglayout mode does not matter, so the fallthrough
2684 edge can go to any basic block (and not just to bb->next_bb, like in
2686 else if (single_pred_p (else_edge
->dest
)
2687 && single_succ_p (else_edge
->dest
)
2688 && single_succ (else_edge
->dest
) == then_edge
->dest
)
2690 /* The noce transformations do not apply to IF-ELSE-JOIN blocks.
2691 To make this work, we have to invert the THEN and ELSE blocks
2692 and reverse the jump condition. */
2693 then_bb
= else_edge
->dest
;
2694 else_bb
= NULL_BLOCK
;
2695 join_bb
= single_succ (then_bb
);
2696 then_else_reversed
= true;
2699 /* Not a form we can handle. */
2702 /* The edges of the THEN and ELSE blocks cannot have complex edges. */
2703 if (single_succ_edge (then_bb
)->flags
& EDGE_COMPLEX
)
2706 && single_succ_edge (else_bb
)->flags
& EDGE_COMPLEX
)
2709 num_possible_if_blocks
++;
2714 "\nIF-THEN%s-JOIN block found, pass %d, test %d, then %d",
2715 (else_bb
) ? "-ELSE" : "",
2716 pass
, test_bb
->index
, then_bb
->index
);
2719 fprintf (dump_file
, ", else %d", else_bb
->index
);
2721 fprintf (dump_file
, ", join %d\n", join_bb
->index
);
2724 /* If the conditional jump is more than just a conditional
2725 jump, then we can not do if-conversion on this block. */
2726 jump
= BB_END (test_bb
);
2727 if (! onlyjump_p (jump
))
2730 /* If this is not a standard conditional jump, we can't parse it. */
2731 cond
= noce_get_condition (jump
,
2733 then_else_reversed
);
2737 /* We must be comparing objects whose modes imply the size. */
2738 if (GET_MODE (XEXP (cond
, 0)) == BLKmode
)
2741 /* Initialize an IF_INFO struct to pass around. */
2742 memset (&if_info
, 0, sizeof if_info
);
2743 if_info
.test_bb
= test_bb
;
2744 if_info
.then_bb
= then_bb
;
2745 if_info
.else_bb
= else_bb
;
2746 if_info
.join_bb
= join_bb
;
2747 if_info
.cond
= cond
;
2748 if_info
.cond_earliest
= cond_earliest
;
2749 if_info
.jump
= jump
;
2750 if_info
.then_else_reversed
= then_else_reversed
;
2752 /* Do the real work. */
2754 if (noce_process_if_block (&if_info
))
2757 if (HAVE_conditional_move
2758 && cond_move_process_if_block (&if_info
))
2765 /* Merge the blocks and mark for local life update. */
2768 merge_if_block (struct ce_if_block
* ce_info
)
2770 basic_block test_bb
= ce_info
->test_bb
; /* last test block */
2771 basic_block then_bb
= ce_info
->then_bb
; /* THEN */
2772 basic_block else_bb
= ce_info
->else_bb
; /* ELSE or NULL */
2773 basic_block join_bb
= ce_info
->join_bb
; /* join block */
2774 basic_block combo_bb
;
2776 /* All block merging is done into the lower block numbers. */
2779 df_set_bb_dirty (test_bb
);
2781 /* Merge any basic blocks to handle && and || subtests. Each of
2782 the blocks are on the fallthru path from the predecessor block. */
2783 if (ce_info
->num_multiple_test_blocks
> 0)
2785 basic_block bb
= test_bb
;
2786 basic_block last_test_bb
= ce_info
->last_test_bb
;
2787 basic_block fallthru
= block_fallthru (bb
);
2792 fallthru
= block_fallthru (bb
);
2793 merge_blocks (combo_bb
, bb
);
2796 while (bb
!= last_test_bb
);
2799 /* Merge TEST block into THEN block. Normally the THEN block won't have a
2800 label, but it might if there were || tests. That label's count should be
2801 zero, and it normally should be removed. */
2805 merge_blocks (combo_bb
, then_bb
);
2809 /* The ELSE block, if it existed, had a label. That label count
2810 will almost always be zero, but odd things can happen when labels
2811 get their addresses taken. */
2814 merge_blocks (combo_bb
, else_bb
);
2818 /* If there was no join block reported, that means it was not adjacent
2819 to the others, and so we cannot merge them. */
2823 rtx last
= BB_END (combo_bb
);
2825 /* The outgoing edge for the current COMBO block should already
2826 be correct. Verify this. */
2827 if (EDGE_COUNT (combo_bb
->succs
) == 0)
2828 gcc_assert (find_reg_note (last
, REG_NORETURN
, NULL
)
2829 || (NONJUMP_INSN_P (last
)
2830 && GET_CODE (PATTERN (last
)) == TRAP_IF
2831 && (TRAP_CONDITION (PATTERN (last
))
2832 == const_true_rtx
)));
2835 /* There should still be something at the end of the THEN or ELSE
2836 blocks taking us to our final destination. */
2837 gcc_assert (JUMP_P (last
)
2838 || (EDGE_SUCC (combo_bb
, 0)->dest
== EXIT_BLOCK_PTR
2840 && SIBLING_CALL_P (last
))
2841 || ((EDGE_SUCC (combo_bb
, 0)->flags
& EDGE_EH
)
2842 && can_throw_internal (last
)));
2845 /* The JOIN block may have had quite a number of other predecessors too.
2846 Since we've already merged the TEST, THEN and ELSE blocks, we should
2847 have only one remaining edge from our if-then-else diamond. If there
2848 is more than one remaining edge, it must come from elsewhere. There
2849 may be zero incoming edges if the THEN block didn't actually join
2850 back up (as with a call to a non-return function). */
2851 else if (EDGE_COUNT (join_bb
->preds
) < 2
2852 && join_bb
!= EXIT_BLOCK_PTR
)
2854 /* We can merge the JOIN cleanly and update the dataflow try
2855 again on this pass.*/
2856 merge_blocks (combo_bb
, join_bb
);
2861 /* We cannot merge the JOIN. */
2863 /* The outgoing edge for the current COMBO block should already
2864 be correct. Verify this. */
2865 gcc_assert (single_succ_p (combo_bb
)
2866 && single_succ (combo_bb
) == join_bb
);
2868 /* Remove the jump and cruft from the end of the COMBO block. */
2869 if (join_bb
!= EXIT_BLOCK_PTR
)
2870 tidy_fallthru_edge (single_succ_edge (combo_bb
));
2873 num_updated_if_blocks
++;
2876 /* Find a block ending in a simple IF condition and try to transform it
2877 in some way. When converting a multi-block condition, put the new code
2878 in the first such block and delete the rest. Return a pointer to this
2879 first block if some transformation was done. Return NULL otherwise. */
2882 find_if_header (basic_block test_bb
, int pass
)
2884 ce_if_block_t ce_info
;
2888 /* The kind of block we're looking for has exactly two successors. */
2889 if (EDGE_COUNT (test_bb
->succs
) != 2)
2892 then_edge
= EDGE_SUCC (test_bb
, 0);
2893 else_edge
= EDGE_SUCC (test_bb
, 1);
2895 if (df_get_bb_dirty (then_edge
->dest
))
2897 if (df_get_bb_dirty (else_edge
->dest
))
2900 /* Neither edge should be abnormal. */
2901 if ((then_edge
->flags
& EDGE_COMPLEX
)
2902 || (else_edge
->flags
& EDGE_COMPLEX
))
2905 /* Nor exit the loop. */
2906 if ((then_edge
->flags
& EDGE_LOOP_EXIT
)
2907 || (else_edge
->flags
& EDGE_LOOP_EXIT
))
2910 /* The THEN edge is canonically the one that falls through. */
2911 if (then_edge
->flags
& EDGE_FALLTHRU
)
2913 else if (else_edge
->flags
& EDGE_FALLTHRU
)
2916 else_edge
= then_edge
;
2920 /* Otherwise this must be a multiway branch of some sort. */
2923 memset (&ce_info
, '\0', sizeof (ce_info
));
2924 ce_info
.test_bb
= test_bb
;
2925 ce_info
.then_bb
= then_edge
->dest
;
2926 ce_info
.else_bb
= else_edge
->dest
;
2927 ce_info
.pass
= pass
;
2929 #ifdef IFCVT_INIT_EXTRA_FIELDS
2930 IFCVT_INIT_EXTRA_FIELDS (&ce_info
);
2933 if (! reload_completed
2934 && noce_find_if_block (test_bb
, then_edge
, else_edge
, pass
))
2937 if (HAVE_conditional_execution
&& reload_completed
2938 && cond_exec_find_if_block (&ce_info
))
2941 if (HAVE_trap
&& HAVE_conditional_trap
2942 && find_cond_trap (test_bb
, then_edge
, else_edge
))
2945 if (dom_info_state (CDI_POST_DOMINATORS
) >= DOM_NO_FAST_QUERY
2946 && (! HAVE_conditional_execution
|| reload_completed
))
2948 if (find_if_case_1 (test_bb
, then_edge
, else_edge
))
2950 if (find_if_case_2 (test_bb
, then_edge
, else_edge
))
2958 fprintf (dump_file
, "Conversion succeeded on pass %d.\n", pass
);
2959 /* Set this so we continue looking. */
2960 cond_exec_changed_p
= TRUE
;
2961 return ce_info
.test_bb
;
2964 /* Return true if a block has two edges, one of which falls through to the next
2965 block, and the other jumps to a specific block, so that we can tell if the
2966 block is part of an && test or an || test. Returns either -1 or the number
2967 of non-note, non-jump, non-USE/CLOBBER insns in the block. */
2970 block_jumps_and_fallthru_p (basic_block cur_bb
, basic_block target_bb
)
2973 int fallthru_p
= FALSE
;
2980 if (!cur_bb
|| !target_bb
)
2983 /* If no edges, obviously it doesn't jump or fallthru. */
2984 if (EDGE_COUNT (cur_bb
->succs
) == 0)
2987 FOR_EACH_EDGE (cur_edge
, ei
, cur_bb
->succs
)
2989 if (cur_edge
->flags
& EDGE_COMPLEX
)
2990 /* Anything complex isn't what we want. */
2993 else if (cur_edge
->flags
& EDGE_FALLTHRU
)
2996 else if (cur_edge
->dest
== target_bb
)
3003 if ((jump_p
& fallthru_p
) == 0)
3006 /* Don't allow calls in the block, since this is used to group && and ||
3007 together for conditional execution support. ??? we should support
3008 conditional execution support across calls for IA-64 some day, but
3009 for now it makes the code simpler. */
3010 end
= BB_END (cur_bb
);
3011 insn
= BB_HEAD (cur_bb
);
3013 while (insn
!= NULL_RTX
)
3020 && GET_CODE (PATTERN (insn
)) != USE
3021 && GET_CODE (PATTERN (insn
)) != CLOBBER
)
3027 insn
= NEXT_INSN (insn
);
3033 /* Determine if a given basic block heads a simple IF-THEN or IF-THEN-ELSE
3034 block. If so, we'll try to convert the insns to not require the branch.
3035 Return TRUE if we were successful at converting the block. */
3038 cond_exec_find_if_block (struct ce_if_block
* ce_info
)
3040 basic_block test_bb
= ce_info
->test_bb
;
3041 basic_block then_bb
= ce_info
->then_bb
;
3042 basic_block else_bb
= ce_info
->else_bb
;
3043 basic_block join_bb
= NULL_BLOCK
;
3048 ce_info
->last_test_bb
= test_bb
;
3050 /* We only ever should get here after reload,
3051 and only if we have conditional execution. */
3052 gcc_assert (HAVE_conditional_execution
&& reload_completed
);
3054 /* Discover if any fall through predecessors of the current test basic block
3055 were && tests (which jump to the else block) or || tests (which jump to
3057 if (single_pred_p (test_bb
)
3058 && single_pred_edge (test_bb
)->flags
== EDGE_FALLTHRU
)
3060 basic_block bb
= single_pred (test_bb
);
3061 basic_block target_bb
;
3062 int max_insns
= MAX_CONDITIONAL_EXECUTE
;
3065 /* Determine if the preceding block is an && or || block. */
3066 if ((n_insns
= block_jumps_and_fallthru_p (bb
, else_bb
)) >= 0)
3068 ce_info
->and_and_p
= TRUE
;
3069 target_bb
= else_bb
;
3071 else if ((n_insns
= block_jumps_and_fallthru_p (bb
, then_bb
)) >= 0)
3073 ce_info
->and_and_p
= FALSE
;
3074 target_bb
= then_bb
;
3077 target_bb
= NULL_BLOCK
;
3079 if (target_bb
&& n_insns
<= max_insns
)
3081 int total_insns
= 0;
3084 ce_info
->last_test_bb
= test_bb
;
3086 /* Found at least one && or || block, look for more. */
3089 ce_info
->test_bb
= test_bb
= bb
;
3090 total_insns
+= n_insns
;
3093 if (!single_pred_p (bb
))
3096 bb
= single_pred (bb
);
3097 n_insns
= block_jumps_and_fallthru_p (bb
, target_bb
);
3099 while (n_insns
>= 0 && (total_insns
+ n_insns
) <= max_insns
);
3101 ce_info
->num_multiple_test_blocks
= blocks
;
3102 ce_info
->num_multiple_test_insns
= total_insns
;
3104 if (ce_info
->and_and_p
)
3105 ce_info
->num_and_and_blocks
= blocks
;
3107 ce_info
->num_or_or_blocks
= blocks
;
3111 /* The THEN block of an IF-THEN combo must have exactly one predecessor,
3112 other than any || blocks which jump to the THEN block. */
3113 if ((EDGE_COUNT (then_bb
->preds
) - ce_info
->num_or_or_blocks
) != 1)
3116 /* The edges of the THEN and ELSE blocks cannot have complex edges. */
3117 FOR_EACH_EDGE (cur_edge
, ei
, then_bb
->preds
)
3119 if (cur_edge
->flags
& EDGE_COMPLEX
)
3123 FOR_EACH_EDGE (cur_edge
, ei
, else_bb
->preds
)
3125 if (cur_edge
->flags
& EDGE_COMPLEX
)
3129 /* The THEN block of an IF-THEN combo must have zero or one successors. */
3130 if (EDGE_COUNT (then_bb
->succs
) > 0
3131 && (!single_succ_p (then_bb
)
3132 || (single_succ_edge (then_bb
)->flags
& EDGE_COMPLEX
)
3133 || (epilogue_completed
&& tablejump_p (BB_END (then_bb
), NULL
, NULL
))))
3136 /* If the THEN block has no successors, conditional execution can still
3137 make a conditional call. Don't do this unless the ELSE block has
3138 only one incoming edge -- the CFG manipulation is too ugly otherwise.
3139 Check for the last insn of the THEN block being an indirect jump, which
3140 is listed as not having any successors, but confuses the rest of the CE
3141 code processing. ??? we should fix this in the future. */
3142 if (EDGE_COUNT (then_bb
->succs
) == 0)
3144 if (single_pred_p (else_bb
))
3146 rtx last_insn
= BB_END (then_bb
);
3149 && NOTE_P (last_insn
)
3150 && last_insn
!= BB_HEAD (then_bb
))
3151 last_insn
= PREV_INSN (last_insn
);
3154 && JUMP_P (last_insn
)
3155 && ! simplejump_p (last_insn
))
3159 else_bb
= NULL_BLOCK
;
3165 /* If the THEN block's successor is the other edge out of the TEST block,
3166 then we have an IF-THEN combo without an ELSE. */
3167 else if (single_succ (then_bb
) == else_bb
)
3170 else_bb
= NULL_BLOCK
;
3173 /* If the THEN and ELSE block meet in a subsequent block, and the ELSE
3174 has exactly one predecessor and one successor, and the outgoing edge
3175 is not complex, then we have an IF-THEN-ELSE combo. */
3176 else if (single_succ_p (else_bb
)
3177 && single_succ (then_bb
) == single_succ (else_bb
)
3178 && single_pred_p (else_bb
)
3179 && ! (single_succ_edge (else_bb
)->flags
& EDGE_COMPLEX
)
3180 && ! (epilogue_completed
&& tablejump_p (BB_END (else_bb
), NULL
, NULL
)))
3181 join_bb
= single_succ (else_bb
);
3183 /* Otherwise it is not an IF-THEN or IF-THEN-ELSE combination. */
3187 num_possible_if_blocks
++;
3192 "\nIF-THEN%s block found, pass %d, start block %d "
3193 "[insn %d], then %d [%d]",
3194 (else_bb
) ? "-ELSE" : "",
3197 BB_HEAD (test_bb
) ? (int)INSN_UID (BB_HEAD (test_bb
)) : -1,
3199 BB_HEAD (then_bb
) ? (int)INSN_UID (BB_HEAD (then_bb
)) : -1);
3202 fprintf (dump_file
, ", else %d [%d]",
3204 BB_HEAD (else_bb
) ? (int)INSN_UID (BB_HEAD (else_bb
)) : -1);
3206 fprintf (dump_file
, ", join %d [%d]",
3208 BB_HEAD (join_bb
) ? (int)INSN_UID (BB_HEAD (join_bb
)) : -1);
3210 if (ce_info
->num_multiple_test_blocks
> 0)
3211 fprintf (dump_file
, ", %d %s block%s last test %d [%d]",
3212 ce_info
->num_multiple_test_blocks
,
3213 (ce_info
->and_and_p
) ? "&&" : "||",
3214 (ce_info
->num_multiple_test_blocks
== 1) ? "" : "s",
3215 ce_info
->last_test_bb
->index
,
3216 ((BB_HEAD (ce_info
->last_test_bb
))
3217 ? (int)INSN_UID (BB_HEAD (ce_info
->last_test_bb
))
3220 fputc ('\n', dump_file
);
3223 /* Make sure IF, THEN, and ELSE, blocks are adjacent. Actually, we get the
3224 first condition for free, since we've already asserted that there's a
3225 fallthru edge from IF to THEN. Likewise for the && and || blocks, since
3226 we checked the FALLTHRU flag, those are already adjacent to the last IF
3228 /* ??? As an enhancement, move the ELSE block. Have to deal with
3229 BLOCK notes, if by no other means than backing out the merge if they
3230 exist. Sticky enough I don't want to think about it now. */
3232 if (else_bb
&& (next
= next
->next_bb
) != else_bb
)
3234 if ((next
= next
->next_bb
) != join_bb
&& join_bb
!= EXIT_BLOCK_PTR
)
3242 /* Do the real work. */
3244 ce_info
->else_bb
= else_bb
;
3245 ce_info
->join_bb
= join_bb
;
3247 /* If we have && and || tests, try to first handle combining the && and ||
3248 tests into the conditional code, and if that fails, go back and handle
3249 it without the && and ||, which at present handles the && case if there
3250 was no ELSE block. */
3251 if (cond_exec_process_if_block (ce_info
, TRUE
))
3254 if (ce_info
->num_multiple_test_blocks
)
3258 if (cond_exec_process_if_block (ce_info
, FALSE
))
3265 /* Convert a branch over a trap, or a branch
3266 to a trap, into a conditional trap. */
3269 find_cond_trap (basic_block test_bb
, edge then_edge
, edge else_edge
)
3271 basic_block then_bb
= then_edge
->dest
;
3272 basic_block else_bb
= else_edge
->dest
;
3273 basic_block other_bb
, trap_bb
;
3274 rtx trap
, jump
, cond
, cond_earliest
, seq
;
3277 /* Locate the block with the trap instruction. */
3278 /* ??? While we look for no successors, we really ought to allow
3279 EH successors. Need to fix merge_if_block for that to work. */
3280 if ((trap
= block_has_only_trap (then_bb
)) != NULL
)
3281 trap_bb
= then_bb
, other_bb
= else_bb
;
3282 else if ((trap
= block_has_only_trap (else_bb
)) != NULL
)
3283 trap_bb
= else_bb
, other_bb
= then_bb
;
3289 fprintf (dump_file
, "\nTRAP-IF block found, start %d, trap %d\n",
3290 test_bb
->index
, trap_bb
->index
);
3293 /* If this is not a standard conditional jump, we can't parse it. */
3294 jump
= BB_END (test_bb
);
3295 cond
= noce_get_condition (jump
, &cond_earliest
, false);
3299 /* If the conditional jump is more than just a conditional jump, then
3300 we can not do if-conversion on this block. */
3301 if (! onlyjump_p (jump
))
3304 /* We must be comparing objects whose modes imply the size. */
3305 if (GET_MODE (XEXP (cond
, 0)) == BLKmode
)
3308 /* Reverse the comparison code, if necessary. */
3309 code
= GET_CODE (cond
);
3310 if (then_bb
== trap_bb
)
3312 code
= reversed_comparison_code (cond
, jump
);
3313 if (code
== UNKNOWN
)
3317 /* Attempt to generate the conditional trap. */
3318 seq
= gen_cond_trap (code
, copy_rtx (XEXP (cond
, 0)),
3319 copy_rtx (XEXP (cond
, 1)),
3320 TRAP_CODE (PATTERN (trap
)));
3324 /* Emit the new insns before cond_earliest. */
3325 emit_insn_before_setloc (seq
, cond_earliest
, INSN_LOCATOR (trap
));
3327 /* Delete the trap block if possible. */
3328 remove_edge (trap_bb
== then_bb
? then_edge
: else_edge
);
3329 df_set_bb_dirty (test_bb
);
3330 df_set_bb_dirty (then_bb
);
3331 df_set_bb_dirty (else_bb
);
3333 if (EDGE_COUNT (trap_bb
->preds
) == 0)
3335 delete_basic_block (trap_bb
);
3339 /* Wire together the blocks again. */
3340 if (current_ir_type () == IR_RTL_CFGLAYOUT
)
3341 single_succ_edge (test_bb
)->flags
|= EDGE_FALLTHRU
;
3346 lab
= JUMP_LABEL (jump
);
3347 newjump
= emit_jump_insn_after (gen_jump (lab
), jump
);
3348 LABEL_NUSES (lab
) += 1;
3349 JUMP_LABEL (newjump
) = lab
;
3350 emit_barrier_after (newjump
);
3354 if (can_merge_blocks_p (test_bb
, other_bb
))
3356 merge_blocks (test_bb
, other_bb
);
3360 num_updated_if_blocks
++;
3364 /* Subroutine of find_cond_trap: if BB contains only a trap insn,
3368 block_has_only_trap (basic_block bb
)
3372 /* We're not the exit block. */
3373 if (bb
== EXIT_BLOCK_PTR
)
3376 /* The block must have no successors. */
3377 if (EDGE_COUNT (bb
->succs
) > 0)
3380 /* The only instruction in the THEN block must be the trap. */
3381 trap
= first_active_insn (bb
);
3382 if (! (trap
== BB_END (bb
)
3383 && GET_CODE (PATTERN (trap
)) == TRAP_IF
3384 && TRAP_CONDITION (PATTERN (trap
)) == const_true_rtx
))
3390 /* Look for IF-THEN-ELSE cases in which one of THEN or ELSE is
3391 transformable, but not necessarily the other. There need be no
3394 Return TRUE if we were successful at converting the block.
3396 Cases we'd like to look at:
3399 if (test) goto over; // x not live
3407 if (! test) goto label;
3410 if (test) goto E; // x not live
3424 (3) // This one's really only interesting for targets that can do
3425 // multiway branching, e.g. IA-64 BBB bundles. For other targets
3426 // it results in multiple branches on a cache line, which often
3427 // does not sit well with predictors.
3429 if (test1) goto E; // predicted not taken
3445 (A) Don't do (2) if the branch is predicted against the block we're
3446 eliminating. Do it anyway if we can eliminate a branch; this requires
3447 that the sole successor of the eliminated block postdominate the other
3450 (B) With CE, on (3) we can steal from both sides of the if, creating
3459 Again, this is most useful if J postdominates.
3461 (C) CE substitutes for helpful life information.
3463 (D) These heuristics need a lot of work. */
3465 /* Tests for case 1 above. */
3468 find_if_case_1 (basic_block test_bb
, edge then_edge
, edge else_edge
)
3470 basic_block then_bb
= then_edge
->dest
;
3471 basic_block else_bb
= else_edge
->dest
;
3475 /* If we are partitioning hot/cold basic blocks, we don't want to
3476 mess up unconditional or indirect jumps that cross between hot
3479 Basic block partitioning may result in some jumps that appear to
3480 be optimizable (or blocks that appear to be mergeable), but which really
3481 must be left untouched (they are required to make it safely across
3482 partition boundaries). See the comments at the top of
3483 bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */
3485 if ((BB_END (then_bb
)
3486 && find_reg_note (BB_END (then_bb
), REG_CROSSING_JUMP
, NULL_RTX
))
3487 || (BB_END (test_bb
)
3488 && find_reg_note (BB_END (test_bb
), REG_CROSSING_JUMP
, NULL_RTX
))
3489 || (BB_END (else_bb
)
3490 && find_reg_note (BB_END (else_bb
), REG_CROSSING_JUMP
,
3494 /* THEN has one successor. */
3495 if (!single_succ_p (then_bb
))
3498 /* THEN does not fall through, but is not strange either. */
3499 if (single_succ_edge (then_bb
)->flags
& (EDGE_COMPLEX
| EDGE_FALLTHRU
))
3502 /* THEN has one predecessor. */
3503 if (!single_pred_p (then_bb
))
3506 /* THEN must do something. */
3507 if (forwarder_block_p (then_bb
))
3510 num_possible_if_blocks
++;
3513 "\nIF-CASE-1 found, start %d, then %d\n",
3514 test_bb
->index
, then_bb
->index
);
3516 /* THEN is small. */
3517 if (! cheap_bb_rtx_cost_p (then_bb
, COSTS_N_INSNS (BRANCH_COST
)))
3520 /* Registers set are dead, or are predicable. */
3521 if (! dead_or_predicable (test_bb
, then_bb
, else_bb
,
3522 single_succ (then_bb
), 1))
3525 /* Conversion went ok, including moving the insns and fixing up the
3526 jump. Adjust the CFG to match. */
3528 /* We can avoid creating a new basic block if then_bb is immediately
3529 followed by else_bb, i.e. deleting then_bb allows test_bb to fall
3532 if (then_bb
->next_bb
== else_bb
3533 && then_bb
->prev_bb
== test_bb
3534 && else_bb
!= EXIT_BLOCK_PTR
)
3536 redirect_edge_succ (FALLTHRU_EDGE (test_bb
), else_bb
);
3540 new_bb
= redirect_edge_and_branch_force (FALLTHRU_EDGE (test_bb
),
3543 df_set_bb_dirty (test_bb
);
3544 df_set_bb_dirty (else_bb
);
3546 then_bb_index
= then_bb
->index
;
3547 delete_basic_block (then_bb
);
3549 /* Make rest of code believe that the newly created block is the THEN_BB
3550 block we removed. */
3553 df_bb_replace (then_bb_index
, new_bb
);
3554 /* Since the fallthru edge was redirected from test_bb to new_bb,
3555 we need to ensure that new_bb is in the same partition as
3556 test bb (you can not fall through across section boundaries). */
3557 BB_COPY_PARTITION (new_bb
, test_bb
);
3561 num_updated_if_blocks
++;
3566 /* Test for case 2 above. */
3569 find_if_case_2 (basic_block test_bb
, edge then_edge
, edge else_edge
)
3571 basic_block then_bb
= then_edge
->dest
;
3572 basic_block else_bb
= else_edge
->dest
;
3576 /* If we are partitioning hot/cold basic blocks, we don't want to
3577 mess up unconditional or indirect jumps that cross between hot
3580 Basic block partitioning may result in some jumps that appear to
3581 be optimizable (or blocks that appear to be mergeable), but which really
3582 must be left untouched (they are required to make it safely across
3583 partition boundaries). See the comments at the top of
3584 bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */
3586 if ((BB_END (then_bb
)
3587 && find_reg_note (BB_END (then_bb
), REG_CROSSING_JUMP
, NULL_RTX
))
3588 || (BB_END (test_bb
)
3589 && find_reg_note (BB_END (test_bb
), REG_CROSSING_JUMP
, NULL_RTX
))
3590 || (BB_END (else_bb
)
3591 && find_reg_note (BB_END (else_bb
), REG_CROSSING_JUMP
,
3595 /* ELSE has one successor. */
3596 if (!single_succ_p (else_bb
))
3599 else_succ
= single_succ_edge (else_bb
);
3601 /* ELSE outgoing edge is not complex. */
3602 if (else_succ
->flags
& EDGE_COMPLEX
)
3605 /* ELSE has one predecessor. */
3606 if (!single_pred_p (else_bb
))
3609 /* THEN is not EXIT. */
3610 if (then_bb
->index
< NUM_FIXED_BLOCKS
)
3613 /* ELSE is predicted or SUCC(ELSE) postdominates THEN. */
3614 note
= find_reg_note (BB_END (test_bb
), REG_BR_PROB
, NULL_RTX
);
3615 if (note
&& INTVAL (XEXP (note
, 0)) >= REG_BR_PROB_BASE
/ 2)
3617 else if (else_succ
->dest
->index
< NUM_FIXED_BLOCKS
3618 || dominated_by_p (CDI_POST_DOMINATORS
, then_bb
,
3624 num_possible_if_blocks
++;
3627 "\nIF-CASE-2 found, start %d, else %d\n",
3628 test_bb
->index
, else_bb
->index
);
3630 /* ELSE is small. */
3631 if (! cheap_bb_rtx_cost_p (else_bb
, COSTS_N_INSNS (BRANCH_COST
)))
3634 /* Registers set are dead, or are predicable. */
3635 if (! dead_or_predicable (test_bb
, else_bb
, then_bb
, else_succ
->dest
, 0))
3638 /* Conversion went ok, including moving the insns and fixing up the
3639 jump. Adjust the CFG to match. */
3641 df_set_bb_dirty (test_bb
);
3642 df_set_bb_dirty (then_bb
);
3643 delete_basic_block (else_bb
);
3646 num_updated_if_blocks
++;
3648 /* ??? We may now fallthru from one of THEN's successors into a join
3649 block. Rerun cleanup_cfg? Examine things manually? Wait? */
3654 /* A subroutine of dead_or_predicable called through for_each_rtx.
3655 Return 1 if a memory is found. */
3658 find_memory (rtx
*px
, void *data ATTRIBUTE_UNUSED
)
3663 /* Used by the code above to perform the actual rtl transformations.
3664 Return TRUE if successful.
3666 TEST_BB is the block containing the conditional branch. MERGE_BB
3667 is the block containing the code to manipulate. NEW_DEST is the
3668 label TEST_BB should be branching to after the conversion.
3669 REVERSEP is true if the sense of the branch should be reversed. */
3672 dead_or_predicable (basic_block test_bb
, basic_block merge_bb
,
3673 basic_block other_bb
, basic_block new_dest
, int reversep
)
3675 rtx head
, end
, jump
, earliest
= NULL_RTX
, old_dest
, new_label
= NULL_RTX
;
3677 jump
= BB_END (test_bb
);
3679 /* Find the extent of the real code in the merge block. */
3680 head
= BB_HEAD (merge_bb
);
3681 end
= BB_END (merge_bb
);
3683 /* If merge_bb ends with a tablejump, predicating/moving insn's
3684 into test_bb and then deleting merge_bb will result in the jumptable
3685 that follows merge_bb being removed along with merge_bb and then we
3686 get an unresolved reference to the jumptable. */
3687 if (tablejump_p (end
, NULL
, NULL
))
3691 head
= NEXT_INSN (head
);
3696 head
= end
= NULL_RTX
;
3699 head
= NEXT_INSN (head
);
3706 head
= end
= NULL_RTX
;
3709 end
= PREV_INSN (end
);
3712 /* Disable handling dead code by conditional execution if the machine needs
3713 to do anything funny with the tests, etc. */
3714 #ifndef IFCVT_MODIFY_TESTS
3715 if (HAVE_conditional_execution
)
3717 /* In the conditional execution case, we have things easy. We know
3718 the condition is reversible. We don't have to check life info
3719 because we're going to conditionally execute the code anyway.
3720 All that's left is making sure the insns involved can actually
3725 cond
= cond_exec_get_condition (jump
);
3729 prob_val
= find_reg_note (jump
, REG_BR_PROB
, NULL_RTX
);
3731 prob_val
= XEXP (prob_val
, 0);
3735 enum rtx_code rev
= reversed_comparison_code (cond
, jump
);
3738 cond
= gen_rtx_fmt_ee (rev
, GET_MODE (cond
), XEXP (cond
, 0),
3741 prob_val
= GEN_INT (REG_BR_PROB_BASE
- INTVAL (prob_val
));
3744 if (! cond_exec_process_insns ((ce_if_block_t
*)0, head
, end
, cond
,
3753 /* In the non-conditional execution case, we have to verify that there
3754 are no trapping operations, no calls, no references to memory, and
3755 that any registers modified are dead at the branch site. */
3757 rtx insn
, cond
, prev
;
3758 bitmap merge_set
, test_live
, test_set
;
3759 unsigned i
, fail
= 0;
3762 /* Check for no calls or trapping operations. */
3763 for (insn
= head
; ; insn
= NEXT_INSN (insn
))
3769 if (may_trap_p (PATTERN (insn
)))
3772 /* ??? Even non-trapping memories such as stack frame
3773 references must be avoided. For stores, we collect
3774 no lifetime info; for reads, we'd have to assert
3775 true_dependence false against every store in the
3777 if (for_each_rtx (&PATTERN (insn
), find_memory
, NULL
))
3784 if (! any_condjump_p (jump
))
3787 /* Find the extent of the conditional. */
3788 cond
= noce_get_condition (jump
, &earliest
, false);
3793 MERGE_SET = set of registers set in MERGE_BB
3794 TEST_LIVE = set of registers live at EARLIEST
3795 TEST_SET = set of registers set between EARLIEST and the
3796 end of the block. */
3798 merge_set
= BITMAP_ALLOC (®_obstack
);
3799 test_live
= BITMAP_ALLOC (®_obstack
);
3800 test_set
= BITMAP_ALLOC (®_obstack
);
3802 /* ??? bb->local_set is only valid during calculate_global_regs_live,
3803 so we must recompute usage for MERGE_BB. Not so bad, I suppose,
3804 since we've already asserted that MERGE_BB is small. */
3805 /* If we allocated new pseudos (e.g. in the conditional move
3806 expander called from noce_emit_cmove), we must resize the
3808 if (max_regno
< max_reg_num ())
3809 max_regno
= max_reg_num ();
3811 FOR_BB_INSNS (merge_bb
, insn
)
3815 unsigned int uid
= INSN_UID (insn
);
3816 struct df_ref
**def_rec
;
3817 for (def_rec
= DF_INSN_UID_DEFS (uid
); *def_rec
; def_rec
++)
3819 struct df_ref
*def
= *def_rec
;
3820 bitmap_set_bit (merge_set
, DF_REF_REGNO (def
));
3825 /* For small register class machines, don't lengthen lifetimes of
3826 hard registers before reload. */
3827 if (SMALL_REGISTER_CLASSES
&& ! reload_completed
)
3829 EXECUTE_IF_SET_IN_BITMAP (merge_set
, 0, i
, bi
)
3831 if (i
< FIRST_PSEUDO_REGISTER
3833 && ! global_regs
[i
])
3838 /* For TEST, we're interested in a range of insns, not a whole block.
3839 Moreover, we're interested in the insns live from OTHER_BB. */
3841 /* The loop below takes the set of live registers
3842 after JUMP, and calculates the live set before EARLIEST. */
3843 bitmap_copy (test_live
, df_get_live_in (other_bb
));
3844 df_simulate_artificial_refs_at_end (test_bb
, test_live
);
3845 for (insn
= jump
; ; insn
= prev
)
3849 df_simulate_find_defs (insn
, test_set
);
3850 df_simulate_one_insn_backwards (test_bb
, insn
, test_live
);
3852 prev
= PREV_INSN (insn
);
3853 if (insn
== earliest
)
3857 /* We can perform the transformation if
3858 MERGE_SET & (TEST_SET | TEST_LIVE)
3860 TEST_SET & DF_LIVE_IN (merge_bb)
3863 if (bitmap_intersect_p (test_set
, merge_set
)
3864 || bitmap_intersect_p (test_live
, merge_set
)
3865 || bitmap_intersect_p (test_set
, df_get_live_in (merge_bb
)))
3868 BITMAP_FREE (merge_set
);
3869 BITMAP_FREE (test_live
);
3870 BITMAP_FREE (test_set
);
3877 /* We don't want to use normal invert_jump or redirect_jump because
3878 we don't want to delete_insn called. Also, we want to do our own
3879 change group management. */
3881 old_dest
= JUMP_LABEL (jump
);
3882 if (other_bb
!= new_dest
)
3884 new_label
= block_label (new_dest
);
3886 ? ! invert_jump_1 (jump
, new_label
)
3887 : ! redirect_jump_1 (jump
, new_label
))
3891 if (! apply_change_group ())
3894 if (other_bb
!= new_dest
)
3896 redirect_jump_2 (jump
, old_dest
, new_label
, 0, reversep
);
3898 redirect_edge_succ (BRANCH_EDGE (test_bb
), new_dest
);
3901 gcov_type count
, probability
;
3902 count
= BRANCH_EDGE (test_bb
)->count
;
3903 BRANCH_EDGE (test_bb
)->count
= FALLTHRU_EDGE (test_bb
)->count
;
3904 FALLTHRU_EDGE (test_bb
)->count
= count
;
3905 probability
= BRANCH_EDGE (test_bb
)->probability
;
3906 BRANCH_EDGE (test_bb
)->probability
3907 = FALLTHRU_EDGE (test_bb
)->probability
;
3908 FALLTHRU_EDGE (test_bb
)->probability
= probability
;
3909 update_br_prob_note (test_bb
);
3913 /* Move the insns out of MERGE_BB to before the branch. */
3918 if (end
== BB_END (merge_bb
))
3919 BB_END (merge_bb
) = PREV_INSN (head
);
3921 /* PR 21767: When moving insns above a conditional branch, REG_EQUAL
3922 notes might become invalid. */
3928 if (! INSN_P (insn
))
3930 note
= find_reg_note (insn
, REG_EQUAL
, NULL_RTX
);
3933 set
= single_set (insn
);
3934 if (!set
|| !function_invariant_p (SET_SRC (set
)))
3935 remove_note (insn
, note
);
3936 } while (insn
!= end
&& (insn
= NEXT_INSN (insn
)));
3938 reorder_insns (head
, end
, PREV_INSN (earliest
));
3941 /* Remove the jump and edge if we can. */
3942 if (other_bb
== new_dest
)
3945 remove_edge (BRANCH_EDGE (test_bb
));
3946 /* ??? Can't merge blocks here, as then_bb is still in use.
3947 At minimum, the merge will get done just before bb-reorder. */
3957 /* Main entry point for all if-conversion. */
3960 if_convert (bool recompute_dominance
)
3967 df_live_add_problem ();
3968 df_live_set_all_dirty ();
3971 num_possible_if_blocks
= 0;
3972 num_updated_if_blocks
= 0;
3973 num_true_changes
= 0;
3975 loop_optimizer_init (AVOID_CFG_MODIFICATIONS
);
3976 mark_loop_exit_edges ();
3977 loop_optimizer_finalize ();
3978 free_dominance_info (CDI_DOMINATORS
);
3980 /* Compute postdominators if we think we'll use them. */
3981 if (HAVE_conditional_execution
|| recompute_dominance
)
3982 calculate_dominance_info (CDI_POST_DOMINATORS
);
3984 df_set_flags (DF_LR_RUN_DCE
);
3986 /* Go through each of the basic blocks looking for things to convert. If we
3987 have conditional execution, we make multiple passes to allow us to handle
3988 IF-THEN{-ELSE} blocks within other IF-THEN{-ELSE} blocks. */
3993 /* Only need to do dce on the first pass. */
3994 df_clear_flags (DF_LR_RUN_DCE
);
3995 cond_exec_changed_p
= FALSE
;
3998 #ifdef IFCVT_MULTIPLE_DUMPS
3999 if (dump_file
&& pass
> 1)
4000 fprintf (dump_file
, "\n\n========== Pass %d ==========\n", pass
);
4006 while (!df_get_bb_dirty (bb
)
4007 && (new_bb
= find_if_header (bb
, pass
)) != NULL
)
4011 #ifdef IFCVT_MULTIPLE_DUMPS
4012 if (dump_file
&& cond_exec_changed_p
)
4013 print_rtl_with_bb (dump_file
, get_insns ());
4016 while (cond_exec_changed_p
);
4018 #ifdef IFCVT_MULTIPLE_DUMPS
4020 fprintf (dump_file
, "\n\n========== no more changes\n");
4023 free_dominance_info (CDI_POST_DOMINATORS
);
4028 clear_aux_for_blocks ();
4030 /* If we allocated new pseudos, we must resize the array for sched1. */
4031 if (max_regno
< max_reg_num ())
4032 max_regno
= max_reg_num ();
4034 /* Write the final stats. */
4035 if (dump_file
&& num_possible_if_blocks
> 0)
4038 "\n%d possible IF blocks searched.\n",
4039 num_possible_if_blocks
);
4041 "%d IF blocks converted.\n",
4042 num_updated_if_blocks
);
4044 "%d true changes made.\n\n\n",
4049 df_remove_problem (df_live
);
4051 #ifdef ENABLE_CHECKING
4052 verify_flow_info ();
4057 gate_handle_if_conversion (void)
4059 return (optimize
> 0);
4062 /* If-conversion and CFG cleanup. */
4064 rest_of_handle_if_conversion (void)
4066 if (flag_if_conversion
)
4069 dump_flow_info (dump_file
, dump_flags
);
4070 cleanup_cfg (CLEANUP_EXPENSIVE
);
4078 struct tree_opt_pass pass_rtl_ifcvt
=
4081 gate_handle_if_conversion
, /* gate */
4082 rest_of_handle_if_conversion
, /* execute */
4085 0, /* static_pass_number */
4086 TV_IFCVT
, /* tv_id */
4087 0, /* properties_required */
4088 0, /* properties_provided */
4089 0, /* properties_destroyed */
4090 0, /* todo_flags_start */
4091 TODO_df_finish
| TODO_verify_rtl_sharing
|
4092 TODO_dump_func
, /* todo_flags_finish */
4097 gate_handle_if_after_combine (void)
4099 return (optimize
> 0 && flag_if_conversion
);
4103 /* Rerun if-conversion, as combine may have simplified things enough
4104 to now meet sequence length restrictions. */
4106 rest_of_handle_if_after_combine (void)
4112 struct tree_opt_pass pass_if_after_combine
=
4115 gate_handle_if_after_combine
, /* gate */
4116 rest_of_handle_if_after_combine
, /* execute */
4119 0, /* static_pass_number */
4120 TV_IFCVT
, /* tv_id */
4121 0, /* properties_required */
4122 0, /* properties_provided */
4123 0, /* properties_destroyed */
4124 0, /* todo_flags_start */
4125 TODO_df_finish
| TODO_verify_rtl_sharing
|
4127 TODO_ggc_collect
, /* todo_flags_finish */
4133 gate_handle_if_after_reload (void)
4135 return (optimize
> 0 && flag_if_conversion2
);
4139 rest_of_handle_if_after_reload (void)
4146 struct tree_opt_pass pass_if_after_reload
=
4149 gate_handle_if_after_reload
, /* gate */
4150 rest_of_handle_if_after_reload
, /* execute */
4153 0, /* static_pass_number */
4154 TV_IFCVT2
, /* tv_id */
4155 0, /* properties_required */
4156 0, /* properties_provided */
4157 0, /* properties_destroyed */
4158 0, /* todo_flags_start */
4159 TODO_df_finish
| TODO_verify_rtl_sharing
|
4161 TODO_ggc_collect
, /* todo_flags_finish */