1 /* Perform instruction reorganizations for delay slot filling.
2 Copyright (C) 1992-2024 Free Software Foundation, Inc.
3 Contributed by Richard Kenner (kenner@vlsi1.ultra.nyu.edu).
4 Hacked by Michael Tiemann (tiemann@cygnus.com).
6 This file is part of GCC.
8 GCC is free software; you can redistribute it and/or modify it under
9 the terms of the GNU General Public License as published by the Free
10 Software Foundation; either version 3, or (at your option) any later
13 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
14 WARRANTY; without even the implied warranty of MERCHANTABILITY or
15 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
18 You should have received a copy of the GNU General Public License
19 along with GCC; see the file COPYING3. If not see
20 <http://www.gnu.org/licenses/>. */
22 /* Instruction reorganization pass.
24 This pass runs after register allocation and final jump
25 optimization. It should be the last pass to run before peephole.
26 It serves primarily to fill delay slots of insns, typically branch
27 and call insns. Other insns typically involve more complicated
28 interactions of data dependencies and resource constraints, and
29 are better handled by scheduling before register allocation (by the
30 function `schedule_insns').
32 The Branch Penalty is the number of extra cycles that are needed to
33 execute a branch insn. On an ideal machine, branches take a single
34 cycle, and the Branch Penalty is 0. Several RISC machines approach
35 branch delays differently:
37 The MIPS has a single branch delay slot. Most insns
38 (except other branches) can be used to fill this slot. When the
39 slot is filled, two insns execute in two cycles, reducing the
40 branch penalty to zero.
42 The SPARC always has a branch delay slot, but its effects can be
43 annulled when the branch is not taken. This means that failing to
44 find other sources of insns, we can hoist an insn from the branch
45 target that would only be safe to execute knowing that the branch
48 The HP-PA always has a branch delay slot. For unconditional branches
49 its effects can be annulled when the branch is taken. The effects
50 of the delay slot in a conditional branch can be nullified for forward
51 taken branches, or for untaken backward branches. This means
52 we can hoist insns from the fall-through path for forward branches or
53 steal insns from the target of backward branches.
55 The TMS320C3x and C4x have three branch delay slots. When the three
56 slots are filled, the branch penalty is zero. Most insns can fill the
57 delay slots except jump insns.
59 Three techniques for filling delay slots have been implemented so far:
61 (1) `fill_simple_delay_slots' is the simplest, most efficient way
62 to fill delay slots. This pass first looks for insns which come
63 from before the branch and which are safe to execute after the
64 branch. Then it searches after the insn requiring delay slots or,
65 in the case of a branch, for insns that are after the point at
66 which the branch merges into the fallthrough code, if such a point
67 exists. When such insns are found, the branch penalty decreases
68 and no code expansion takes place.
70 (2) `fill_eager_delay_slots' is more complicated: it is used for
71 scheduling conditional jumps, or for scheduling jumps which cannot
72 be filled using (1). A machine need not have annulled jumps to use
73 this strategy, but it helps (by keeping more options open).
74 `fill_eager_delay_slots' tries to guess the direction the branch
75 will go; if it guesses right 100% of the time, it can reduce the
76 branch penalty as much as `fill_simple_delay_slots' does. If it
77 guesses wrong 100% of the time, it might as well schedule nops. When
78 `fill_eager_delay_slots' takes insns from the fall-through path of
79 the jump, usually there is no code expansion; when it takes insns
80 from the branch target, there is code expansion if it is not the
81 only way to reach that target.
83 (3) `relax_delay_slots' uses a set of rules to simplify code that
84 has been reorganized by (1) and (2). It finds cases where
85 conditional test can be eliminated, jumps can be threaded, extra
86 insns can be eliminated, etc. It is the job of (1) and (2) to do a
87 good job of scheduling locally; `relax_delay_slots' takes care of
88 making the various individual schedules work well together. It is
89 especially tuned to handle the control flow interactions of branch
90 insns. It does nothing for insns with delay slots that do not
95 #include "coretypes.h"
101 #include "memmodel.h"
104 #include "insn-config.h"
105 #include "emit-rtl.h"
107 #include "insn-attr.h"
108 #include "resource.h"
109 #include "tree-pass.h"
112 /* First, some functions that were used before GCC got a control flow graph.
113 These functions are now only used here in reorg.cc, and have therefore
114 been moved here to avoid inadvertent misuse elsewhere in the compiler. */
116 /* Return the last label to mark the same position as LABEL. Return LABEL
117 itself if it is null or any return rtx. */
120 skip_consecutive_labels (rtx label_or_return
)
124 if (label_or_return
&& ANY_RETURN_P (label_or_return
))
125 return label_or_return
;
127 rtx_insn
*label
= as_a
<rtx_insn
*> (label_or_return
);
129 /* __builtin_unreachable can create a CODE_LABEL followed by a BARRIER.
131 Since reaching the CODE_LABEL is undefined behavior, we can return
132 any code label and we're OK at run time.
134 However, if we return a CODE_LABEL which leads to a shrink-wrapped
135 epilogue, but the path does not have a prologue, then we will trip
136 a sanity check in the dwarf2 cfi code which wants to verify that
137 the CFIs are all the same on the traces leading to the epilogue.
139 So we explicitly disallow looking through BARRIERS here. */
141 insn
!= 0 && !INSN_P (insn
) && !BARRIER_P (insn
);
142 insn
= NEXT_INSN (insn
))
149 /* Insns which have delay slots that have not yet been filled. */
151 static struct obstack unfilled_slots_obstack
;
152 static rtx
*unfilled_firstobj
;
154 /* Define macros to refer to the first and last slot containing unfilled
155 insns. These are used because the list may move and its address
156 should be recomputed at each use. */
158 #define unfilled_slots_base \
159 ((rtx_insn **) obstack_base (&unfilled_slots_obstack))
161 #define unfilled_slots_next \
162 ((rtx_insn **) obstack_next_free (&unfilled_slots_obstack))
164 /* Points to the label before the end of the function, or before a
166 static rtx_code_label
*function_return_label
;
167 /* Likewise for a simple_return. */
168 static rtx_code_label
*function_simple_return_label
;
170 /* Mapping between INSN_UID's and position in the code since INSN_UID's do
171 not always monotonically increase. */
172 static int *uid_to_ruid
;
174 /* Highest valid index in `uid_to_ruid'. */
177 static bool stop_search_p (rtx_insn
*, bool);
178 static bool resource_conflicts_p (struct resources
*, struct resources
*);
179 static bool insn_references_resource_p (rtx
, struct resources
*, bool);
180 static bool insn_sets_resource_p (rtx
, struct resources
*, bool);
181 static rtx_code_label
*find_end_label (rtx
);
182 static rtx_insn
*emit_delay_sequence (rtx_insn
*, const vec
<rtx_insn
*> &,
184 static void add_to_delay_list (rtx_insn
*, vec
<rtx_insn
*> *);
185 static rtx_insn
*delete_from_delay_slot (rtx_insn
*);
186 static void delete_scheduled_jump (rtx_insn
*);
187 static void note_delay_statistics (int, int);
188 static int get_jump_flags (const rtx_insn
*, rtx
);
189 static int mostly_true_jump (rtx
);
190 static rtx
get_branch_condition (const rtx_insn
*, rtx
);
191 static bool condition_dominates_p (rtx
, const rtx_insn
*);
192 static bool redirect_with_delay_slots_safe_p (rtx_insn
*, rtx
, rtx
);
193 static bool redirect_with_delay_list_safe_p (rtx_insn
*, rtx
,
194 const vec
<rtx_insn
*> &);
195 static bool check_annul_list_true_false (bool, const vec
<rtx_insn
*> &);
196 static void steal_delay_list_from_target (rtx_insn
*, rtx
, rtx_sequence
*,
203 static void steal_delay_list_from_fallthrough (rtx_insn
*, rtx
, rtx_sequence
*,
209 static void try_merge_delay_insns (rtx_insn
*, rtx_insn
*);
210 static rtx_insn
*redundant_insn (rtx
, rtx_insn
*, const vec
<rtx_insn
*> &);
211 static bool own_thread_p (rtx
, rtx
, bool);
212 static void update_block (rtx_insn
*, rtx_insn
*);
213 static bool reorg_redirect_jump (rtx_jump_insn
*, rtx
);
214 static void update_reg_dead_notes (rtx_insn
*, rtx_insn
*);
215 static void fix_reg_dead_note (rtx_insn
*, rtx
);
216 static void update_reg_unused_notes (rtx_insn
*, rtx
);
217 static void fill_simple_delay_slots (bool);
218 static void fill_slots_from_thread (rtx_jump_insn
*, rtx
, rtx
, rtx
,
219 bool, bool, bool, int,
220 int *, vec
<rtx_insn
*> *);
221 static void fill_eager_delay_slots (void);
222 static void relax_delay_slots (rtx_insn
*);
223 static void make_return_insns (rtx_insn
*);
225 /* A wrapper around next_active_insn which takes care to return ret_rtx
229 first_active_target_insn (rtx insn
)
231 if (ANY_RETURN_P (insn
))
233 return next_active_insn (as_a
<rtx_insn
*> (insn
));
236 /* Return true iff INSN is a simplejump, or any kind of return insn. */
239 simplejump_or_return_p (rtx insn
)
241 return (JUMP_P (insn
)
242 && (simplejump_p (as_a
<rtx_insn
*> (insn
))
243 || ANY_RETURN_P (PATTERN (insn
))));
246 /* Return TRUE if this insn should stop the search for insn to fill delay
247 slots. LABELS_P indicates that labels should terminate the search.
248 In all cases, jumps terminate the search. */
251 stop_search_p (rtx_insn
*insn
, bool labels_p
)
256 /* If the insn can throw an exception that is caught within the function,
257 it may effectively perform a jump from the viewpoint of the function.
258 Therefore act like for a jump. */
259 if (can_throw_internal (insn
))
262 switch (GET_CODE (insn
))
277 /* OK unless it contains a delay slot or is an `asm' insn of some type.
278 We don't know anything about these. */
279 return (GET_CODE (PATTERN (insn
)) == SEQUENCE
280 || GET_CODE (PATTERN (insn
)) == ASM_INPUT
281 || asm_noperands (PATTERN (insn
)) >= 0);
288 /* Return TRUE if any resources are marked in both RES1 and RES2 or if either
289 resource set contains a volatile memory reference. Otherwise, return FALSE. */
292 resource_conflicts_p (struct resources
*res1
, struct resources
*res2
)
294 if ((res1
->cc
&& res2
->cc
) || (res1
->memory
&& res2
->memory
)
295 || res1
->volatil
|| res2
->volatil
)
298 return hard_reg_set_intersect_p (res1
->regs
, res2
->regs
);
301 /* Return TRUE if any resource marked in RES, a `struct resources', is
302 referenced by INSN. If INCLUDE_DELAYED_EFFECTS is set, return if the called
303 routine is using those resources.
305 We compute this by computing all the resources referenced by INSN and
306 seeing if this conflicts with RES. It might be faster to directly check
307 ourselves, and this is the way it used to work, but it means duplicating
308 a large block of complex code. */
311 insn_references_resource_p (rtx insn
, struct resources
*res
,
312 bool include_delayed_effects
)
314 struct resources insn_res
;
316 CLEAR_RESOURCE (&insn_res
);
317 mark_referenced_resources (insn
, &insn_res
, include_delayed_effects
);
318 return resource_conflicts_p (&insn_res
, res
);
321 /* Return TRUE if INSN modifies resources that are marked in RES.
322 INCLUDE_DELAYED_EFFECTS is set if the actions of that routine should be
326 insn_sets_resource_p (rtx insn
, struct resources
*res
,
327 bool include_delayed_effects
)
329 struct resources insn_sets
;
331 CLEAR_RESOURCE (&insn_sets
);
332 mark_set_resources (insn
, &insn_sets
, 0,
333 (include_delayed_effects
336 return resource_conflicts_p (&insn_sets
, res
);
339 /* Find a label at the end of the function or before a RETURN. If there
340 is none, try to make one. If that fails, returns 0.
342 The property of such a label is that it is placed just before the
343 epilogue or a bare RETURN insn, so that another bare RETURN can be
344 turned into a jump to the label unconditionally. In particular, the
345 label cannot be placed before a RETURN insn with a filled delay slot.
347 ??? There may be a problem with the current implementation. Suppose
348 we start with a bare RETURN insn and call find_end_label. It may set
349 function_return_label just before the RETURN. Suppose the machinery
350 is able to fill the delay slot of the RETURN insn afterwards. Then
351 function_return_label is no longer valid according to the property
352 described above and find_end_label will still return it unmodified.
353 Note that this is probably mitigated by the following observation:
354 once function_return_label is made, it is very likely the target of
355 a jump, so filling the delay slot of the RETURN will be much more
357 KIND is either simple_return_rtx or ret_rtx, indicating which type of
358 return we're looking for. */
360 static rtx_code_label
*
361 find_end_label (rtx kind
)
364 rtx_code_label
**plabel
;
367 plabel
= &function_return_label
;
370 gcc_assert (kind
== simple_return_rtx
);
371 plabel
= &function_simple_return_label
;
374 /* If we found one previously, return it. */
378 /* Otherwise, see if there is a label at the end of the function. If there
379 is, it must be that RETURN insns aren't needed, so that is our return
380 label and we don't have to do anything else. */
382 insn
= get_last_insn ();
384 || (NONJUMP_INSN_P (insn
)
385 && (GET_CODE (PATTERN (insn
)) == USE
386 || GET_CODE (PATTERN (insn
)) == CLOBBER
)))
387 insn
= PREV_INSN (insn
);
389 /* When a target threads its epilogue we might already have a
390 suitable return insn. If so put a label before it for the
391 function_return_label. */
393 && JUMP_P (PREV_INSN (insn
))
394 && PATTERN (PREV_INSN (insn
)) == kind
)
396 rtx_insn
*temp
= PREV_INSN (PREV_INSN (insn
));
397 rtx_code_label
*label
= gen_label_rtx ();
398 LABEL_NUSES (label
) = 0;
400 /* Put the label before any USE insns that may precede the RETURN
402 while (GET_CODE (temp
) == USE
)
403 temp
= PREV_INSN (temp
);
405 emit_label_after (label
, temp
);
409 else if (LABEL_P (insn
))
410 *plabel
= as_a
<rtx_code_label
*> (insn
);
413 rtx_code_label
*label
= gen_label_rtx ();
414 LABEL_NUSES (label
) = 0;
415 /* If the basic block reorder pass moves the return insn to
416 some other place try to locate it again and put our
417 function_return_label there. */
418 while (insn
&& ! (JUMP_P (insn
) && (PATTERN (insn
) == kind
)))
419 insn
= PREV_INSN (insn
);
422 insn
= PREV_INSN (insn
);
424 /* Put the label before any USE insns that may precede the
426 while (GET_CODE (insn
) == USE
)
427 insn
= PREV_INSN (insn
);
429 emit_label_after (label
, insn
);
433 if (targetm
.have_epilogue () && ! targetm
.have_return ())
434 /* The RETURN insn has its delay slot filled so we cannot
435 emit the label just before it. Since we already have
436 an epilogue and cannot emit a new RETURN, we cannot
437 emit the label at all. */
440 /* Otherwise, make a new label and emit a RETURN and BARRIER,
443 if (targetm
.have_return ())
445 /* The return we make may have delay slots too. */
446 rtx_insn
*pat
= targetm
.gen_return ();
447 rtx_insn
*insn
= emit_jump_insn (pat
);
448 set_return_jump_label (insn
);
450 if (num_delay_slots (insn
) > 0)
451 obstack_ptr_grow (&unfilled_slots_obstack
, insn
);
457 /* Show one additional use for this label so it won't go away until
459 ++LABEL_NUSES (*plabel
);
464 /* Put INSN and LIST together in a SEQUENCE rtx of LENGTH, and replace
465 the pattern of INSN with the SEQUENCE.
467 Returns the insn containing the SEQUENCE that replaces INSN. */
470 emit_delay_sequence (rtx_insn
*insn
, const vec
<rtx_insn
*> &list
, int length
)
472 /* Allocate the rtvec to hold the insns and the SEQUENCE. */
473 rtvec seqv
= rtvec_alloc (length
+ 1);
474 rtx seq
= gen_rtx_SEQUENCE (VOIDmode
, seqv
);
475 rtx_insn
*seq_insn
= make_insn_raw (seq
);
477 /* If DELAY_INSN has a location, use it for SEQ_INSN. If DELAY_INSN does
478 not have a location, but one of the delayed insns does, we pick up a
479 location from there later. */
480 INSN_LOCATION (seq_insn
) = INSN_LOCATION (insn
);
482 /* Unlink INSN from the insn chain, so that we can put it into
483 the SEQUENCE. Remember where we want to emit SEQUENCE in AFTER. */
484 rtx_insn
*after
= PREV_INSN (insn
);
486 SET_NEXT_INSN (insn
) = SET_PREV_INSN (insn
) = NULL
;
488 /* Build our SEQUENCE and rebuild the insn chain. */
490 XVECEXP (seq
, 0, 0) = emit_insn (insn
);
492 unsigned int delay_insns
= list
.length ();
493 gcc_assert (delay_insns
== (unsigned int) length
);
494 for (unsigned int i
= 0; i
< delay_insns
; i
++)
496 rtx_insn
*tem
= list
[i
];
499 /* Show that this copy of the insn isn't deleted. */
500 tem
->set_undeleted ();
502 /* Unlink insn from its original place, and re-emit it into
504 SET_NEXT_INSN (tem
) = SET_PREV_INSN (tem
) = NULL
;
505 XVECEXP (seq
, 0, i
+ 1) = emit_insn (tem
);
507 /* SPARC assembler, for instance, emit warning when debug info is output
508 into the delay slot. */
509 if (INSN_LOCATION (tem
) && !INSN_LOCATION (seq_insn
))
510 INSN_LOCATION (seq_insn
) = INSN_LOCATION (tem
);
511 INSN_LOCATION (tem
) = 0;
513 for (note
= REG_NOTES (tem
); note
; note
= next
)
515 next
= XEXP (note
, 1);
516 switch (REG_NOTE_KIND (note
))
519 /* Remove any REG_DEAD notes because we can't rely on them now
520 that the insn has been moved. */
521 remove_note (tem
, note
);
524 case REG_LABEL_OPERAND
:
525 case REG_LABEL_TARGET
:
526 /* Keep the label reference count up to date. */
527 if (LABEL_P (XEXP (note
, 0)))
528 LABEL_NUSES (XEXP (note
, 0)) ++;
538 /* Splice our SEQUENCE into the insn stream where INSN used to be. */
539 add_insn_after (seq_insn
, after
, NULL
);
544 /* Add INSN to DELAY_LIST and return the head of the new list. The list must
545 be in the order in which the insns are to be executed. */
548 add_to_delay_list (rtx_insn
*insn
, vec
<rtx_insn
*> *delay_list
)
550 /* If INSN has its block number recorded, clear it since we may
551 be moving the insn to a new block. */
552 clear_hashed_info_for_insn (insn
);
554 delay_list
->safe_push (insn
);
557 /* Delete INSN from the delay slot of the insn that it is in, which may
558 produce an insn with no delay slots. Return the new insn. */
561 delete_from_delay_slot (rtx_insn
*insn
)
563 rtx_insn
*trial
, *seq_insn
, *prev
;
565 bool had_barrier
= false;
568 /* We first must find the insn containing the SEQUENCE with INSN in its
569 delay slot. Do this by finding an insn, TRIAL, where
570 PREV_INSN (NEXT_INSN (TRIAL)) != TRIAL. */
573 PREV_INSN (NEXT_INSN (trial
)) == trial
;
574 trial
= NEXT_INSN (trial
))
577 seq_insn
= PREV_INSN (NEXT_INSN (trial
));
578 seq
= as_a
<rtx_sequence
*> (PATTERN (seq_insn
));
580 if (NEXT_INSN (seq_insn
) && BARRIER_P (NEXT_INSN (seq_insn
)))
583 /* Create a delay list consisting of all the insns other than the one
584 we are deleting (unless we were the only one). */
585 auto_vec
<rtx_insn
*, 5> delay_list
;
587 for (i
= 1; i
< seq
->len (); i
++)
588 if (seq
->insn (i
) != insn
)
589 add_to_delay_list (seq
->insn (i
), &delay_list
);
591 /* Delete the old SEQUENCE, re-emit the insn that used to have the delay
592 list, and rebuild the delay list if non-empty. */
593 prev
= PREV_INSN (seq_insn
);
594 trial
= seq
->insn (0);
595 delete_related_insns (seq_insn
);
596 add_insn_after (trial
, prev
, NULL
);
598 /* If there was a barrier after the old SEQUENCE, remit it. */
600 emit_barrier_after (trial
);
602 /* If there are any delay insns, remit them. Otherwise clear the
604 if (!delay_list
.is_empty ())
605 trial
= emit_delay_sequence (trial
, delay_list
, XVECLEN (seq
, 0) - 2);
606 else if (JUMP_P (trial
))
607 INSN_ANNULLED_BRANCH_P (trial
) = 0;
609 INSN_FROM_TARGET_P (insn
) = 0;
611 /* Show we need to fill this insn again. */
612 obstack_ptr_grow (&unfilled_slots_obstack
, trial
);
617 /* Delete INSN, a JUMP_INSN. */
620 delete_scheduled_jump (rtx_insn
*insn
)
622 delete_related_insns (insn
);
625 /* Counters for delay-slot filling. */
627 #define NUM_REORG_FUNCTIONS 2
628 #define MAX_DELAY_HISTOGRAM 3
629 #define MAX_REORG_PASSES 2
631 static int num_insns_needing_delays
[NUM_REORG_FUNCTIONS
][MAX_REORG_PASSES
];
633 static int num_filled_delays
[NUM_REORG_FUNCTIONS
][MAX_DELAY_HISTOGRAM
+1][MAX_REORG_PASSES
];
635 static int reorg_pass_number
;
638 note_delay_statistics (int slots_filled
, int index
)
640 num_insns_needing_delays
[index
][reorg_pass_number
]++;
641 if (slots_filled
> MAX_DELAY_HISTOGRAM
)
642 slots_filled
= MAX_DELAY_HISTOGRAM
;
643 num_filled_delays
[index
][slots_filled
][reorg_pass_number
]++;
646 /* Optimize the following cases:
648 1. When a conditional branch skips over only one instruction,
649 use an annulling branch and put that insn in the delay slot.
650 Use either a branch that annuls when the condition if true or
651 invert the test with a branch that annuls when the condition is
652 false. This saves insns, since otherwise we must copy an insn
655 (orig) (skip) (otherwise)
656 Bcc.n L1 Bcc',a L1 Bcc,a L1'
663 2. When a conditional branch skips over only one instruction,
664 and after that, it unconditionally branches somewhere else,
665 perform the similar optimization. This saves executing the
666 second branch in the case where the inverted condition is true.
675 This should be expanded to skip over N insns, where N is the number
676 of delay slots required. */
679 optimize_skip (rtx_jump_insn
*insn
, vec
<rtx_insn
*> *delay_list
)
681 rtx_insn
*trial
= next_nonnote_insn (insn
);
682 rtx_insn
*next_trial
= next_active_insn (trial
);
685 flags
= get_jump_flags (insn
, JUMP_LABEL (insn
));
688 || !NONJUMP_INSN_P (trial
)
689 || GET_CODE (PATTERN (trial
)) == SEQUENCE
690 || recog_memoized (trial
) < 0
691 || (! eligible_for_annul_false (insn
, 0, trial
, flags
)
692 && ! eligible_for_annul_true (insn
, 0, trial
, flags
))
693 || RTX_FRAME_RELATED_P (trial
)
694 || can_throw_internal (trial
))
697 /* There are two cases where we are just executing one insn (we assume
698 here that a branch requires only one insn; this should be generalized
699 at some point): Where the branch goes around a single insn or where
700 we have one insn followed by a branch to the same label we branch to.
701 In both of these cases, inverting the jump and annulling the delay
702 slot give the same effect in fewer insns. */
703 if (next_trial
== next_active_insn (JUMP_LABEL_AS_INSN (insn
))
705 && simplejump_or_return_p (next_trial
)
706 && JUMP_LABEL (insn
) == JUMP_LABEL (next_trial
)))
708 if (eligible_for_annul_false (insn
, 0, trial
, flags
))
710 if (invert_jump (insn
, JUMP_LABEL (insn
), 1))
711 INSN_FROM_TARGET_P (trial
) = 1;
712 else if (! eligible_for_annul_true (insn
, 0, trial
, flags
))
716 add_to_delay_list (trial
, delay_list
);
717 next_trial
= next_active_insn (trial
);
718 update_block (trial
, trial
);
719 delete_related_insns (trial
);
721 /* Also, if we are targeting an unconditional
722 branch, thread our jump to the target of that branch. Don't
723 change this into a RETURN here, because it may not accept what
724 we have in the delay slot. We'll fix this up later. */
725 if (next_trial
&& simplejump_or_return_p (next_trial
))
727 rtx target_label
= JUMP_LABEL (next_trial
);
728 if (ANY_RETURN_P (target_label
))
729 target_label
= find_end_label (target_label
);
733 /* Recompute the flags based on TARGET_LABEL since threading
734 the jump to TARGET_LABEL may change the direction of the
735 jump (which may change the circumstances in which the
736 delay slot is nullified). */
737 flags
= get_jump_flags (insn
, target_label
);
738 if (eligible_for_annul_true (insn
, 0, trial
, flags
))
739 reorg_redirect_jump (insn
, target_label
);
743 INSN_ANNULLED_BRANCH_P (insn
) = 1;
747 /* Encode and return branch direction and prediction information for
748 INSN assuming it will jump to LABEL.
750 Non conditional branches return no direction information and
751 are predicted as very likely taken. */
754 get_jump_flags (const rtx_insn
*insn
, rtx label
)
758 /* get_jump_flags can be passed any insn with delay slots, these may
759 be INSNs, CALL_INSNs, or JUMP_INSNs. Only JUMP_INSNs have branch
760 direction information, and only if they are conditional jumps.
762 If LABEL is a return, then there is no way to determine the branch
765 && (condjump_p (insn
) || condjump_in_parallel_p (insn
))
766 && !ANY_RETURN_P (label
)
767 && INSN_UID (insn
) <= max_uid
768 && INSN_UID (label
) <= max_uid
)
770 = (uid_to_ruid
[INSN_UID (label
)] > uid_to_ruid
[INSN_UID (insn
)])
771 ? ATTR_FLAG_forward
: ATTR_FLAG_backward
;
772 /* No valid direction information. */
779 /* Return truth value of the statement that this branch
780 is mostly taken. If we think that the branch is extremely likely
781 to be taken, we return 2. If the branch is slightly more likely to be
782 taken, return 1. If the branch is slightly less likely to be taken,
783 return 0 and if the branch is highly unlikely to be taken, return -1. */
786 mostly_true_jump (rtx jump_insn
)
788 /* If branch probabilities are available, then use that number since it
789 always gives a correct answer. */
790 rtx note
= find_reg_note (jump_insn
, REG_BR_PROB
, 0);
793 int prob
= profile_probability::from_reg_br_prob_note (XINT (note
, 0))
794 .to_reg_br_prob_base ();
796 if (prob
>= REG_BR_PROB_BASE
* 9 / 10)
798 else if (prob
>= REG_BR_PROB_BASE
/ 2)
800 else if (prob
>= REG_BR_PROB_BASE
/ 10)
806 /* If there is no note, assume branches are not taken.
807 This should be rare. */
811 /* Return the condition under which INSN will branch to TARGET. If TARGET
812 is zero, return the condition under which INSN will return. If INSN is
813 an unconditional branch, return const_true_rtx. If INSN isn't a simple
814 type of jump, or it doesn't go to TARGET, return 0. */
817 get_branch_condition (const rtx_insn
*insn
, rtx target
)
819 rtx pat
= PATTERN (insn
);
822 if (condjump_in_parallel_p (insn
))
823 pat
= XVECEXP (pat
, 0, 0);
825 if (ANY_RETURN_P (pat
) && pat
== target
)
826 return const_true_rtx
;
828 if (GET_CODE (pat
) != SET
|| SET_DEST (pat
) != pc_rtx
)
832 if (GET_CODE (src
) == LABEL_REF
&& label_ref_label (src
) == target
)
833 return const_true_rtx
;
835 else if (GET_CODE (src
) == IF_THEN_ELSE
836 && XEXP (src
, 2) == pc_rtx
837 && ((GET_CODE (XEXP (src
, 1)) == LABEL_REF
838 && label_ref_label (XEXP (src
, 1)) == target
)
839 || (ANY_RETURN_P (XEXP (src
, 1)) && XEXP (src
, 1) == target
)))
840 return XEXP (src
, 0);
842 else if (GET_CODE (src
) == IF_THEN_ELSE
843 && XEXP (src
, 1) == pc_rtx
844 && ((GET_CODE (XEXP (src
, 2)) == LABEL_REF
845 && label_ref_label (XEXP (src
, 2)) == target
)
846 || (ANY_RETURN_P (XEXP (src
, 2)) && XEXP (src
, 2) == target
)))
849 rev
= reversed_comparison_code (XEXP (src
, 0), insn
);
851 return gen_rtx_fmt_ee (rev
, GET_MODE (XEXP (src
, 0)),
852 XEXP (XEXP (src
, 0), 0),
853 XEXP (XEXP (src
, 0), 1));
859 /* Return true if CONDITION is more strict than the condition of
860 INSN, i.e., if INSN will always branch if CONDITION is true. */
863 condition_dominates_p (rtx condition
, const rtx_insn
*insn
)
865 rtx other_condition
= get_branch_condition (insn
, JUMP_LABEL (insn
));
866 enum rtx_code code
= GET_CODE (condition
);
867 enum rtx_code other_code
;
869 if (rtx_equal_p (condition
, other_condition
)
870 || other_condition
== const_true_rtx
)
873 else if (condition
== const_true_rtx
|| other_condition
== 0)
876 other_code
= GET_CODE (other_condition
);
877 if (GET_RTX_LENGTH (code
) != 2 || GET_RTX_LENGTH (other_code
) != 2
878 || ! rtx_equal_p (XEXP (condition
, 0), XEXP (other_condition
, 0))
879 || ! rtx_equal_p (XEXP (condition
, 1), XEXP (other_condition
, 1)))
882 return comparison_dominates_p (code
, other_code
);
885 /* Return true if redirecting JUMP to NEWLABEL does not invalidate
886 any insns already in the delay slot of JUMP. */
889 redirect_with_delay_slots_safe_p (rtx_insn
*jump
, rtx newlabel
, rtx seq
)
892 rtx_sequence
*pat
= as_a
<rtx_sequence
*> (PATTERN (seq
));
894 /* Make sure all the delay slots of this jump would still
895 be valid after threading the jump. If they are still
896 valid, then return nonzero. */
898 flags
= get_jump_flags (jump
, newlabel
);
899 for (i
= 1; i
< pat
->len (); i
++)
901 #if ANNUL_IFFALSE_SLOTS
902 (INSN_ANNULLED_BRANCH_P (jump
)
903 && INSN_FROM_TARGET_P (pat
->insn (i
)))
904 ? eligible_for_annul_false (jump
, i
- 1, pat
->insn (i
), flags
) :
906 #if ANNUL_IFTRUE_SLOTS
907 (INSN_ANNULLED_BRANCH_P (jump
)
908 && ! INSN_FROM_TARGET_P (XVECEXP (pat
, 0, i
)))
909 ? eligible_for_annul_true (jump
, i
- 1, pat
->insn (i
), flags
) :
911 eligible_for_delay (jump
, i
- 1, pat
->insn (i
), flags
)))
914 return (i
== pat
->len ());
917 /* Return true if redirecting JUMP to NEWLABEL does not invalidate
918 any insns we wish to place in the delay slot of JUMP. */
921 redirect_with_delay_list_safe_p (rtx_insn
*jump
, rtx newlabel
,
922 const vec
<rtx_insn
*> &delay_list
)
924 /* Make sure all the insns in DELAY_LIST would still be
925 valid after threading the jump. If they are still
926 valid, then return true. */
928 int flags
= get_jump_flags (jump
, newlabel
);
929 unsigned int delay_insns
= delay_list
.length ();
931 for (; i
< delay_insns
; i
++)
933 #if ANNUL_IFFALSE_SLOTS
934 (INSN_ANNULLED_BRANCH_P (jump
)
935 && INSN_FROM_TARGET_P (delay_list
[i
]))
936 ? eligible_for_annul_false (jump
, i
, delay_list
[i
], flags
) :
938 #if ANNUL_IFTRUE_SLOTS
939 (INSN_ANNULLED_BRANCH_P (jump
)
940 && ! INSN_FROM_TARGET_P (delay_list
[i
]))
941 ? eligible_for_annul_true (jump
, i
, delay_list
[i
], flags
) :
943 eligible_for_delay (jump
, i
, delay_list
[i
], flags
)))
946 return i
== delay_insns
;
949 /* DELAY_LIST is a list of insns that have already been placed into delay
950 slots. See if all of them have the same annulling status as ANNUL_TRUE_P.
951 If not, return false; otherwise return true. */
954 check_annul_list_true_false (bool annul_true_p
,
955 const vec
<rtx_insn
*> &delay_list
)
959 FOR_EACH_VEC_ELT (delay_list
, i
, trial
)
960 if ((annul_true_p
&& INSN_FROM_TARGET_P (trial
))
961 || (!annul_true_p
&& !INSN_FROM_TARGET_P (trial
)))
967 /* INSN branches to an insn whose pattern SEQ is a SEQUENCE. Given that
968 the condition tested by INSN is CONDITION and the resources shown in
969 OTHER_NEEDED are needed after INSN, see whether INSN can take all the insns
970 from SEQ's delay list, in addition to whatever insns it may execute
971 (in DELAY_LIST). SETS and NEEDED are denote resources already set and
972 needed while searching for delay slot insns. Return the concatenated
973 delay list if possible, otherwise, return 0.
975 SLOTS_TO_FILL is the total number of slots required by INSN, and
976 PSLOTS_FILLED points to the number filled so far (also the number of
977 insns in DELAY_LIST). It is updated with the number that have been
978 filled from the SEQUENCE, if any.
980 PANNUL_P points to a nonzero value if we already know that we need
981 to annul INSN. If this routine determines that annulling is needed,
982 it may set that value to true.
984 PNEW_THREAD points to a location that is to receive the place at which
985 execution should continue. */
988 steal_delay_list_from_target (rtx_insn
*insn
, rtx condition
, rtx_sequence
*seq
,
989 vec
<rtx_insn
*> *delay_list
,
990 struct resources
*sets
,
991 struct resources
*needed
,
992 struct resources
*other_needed
,
993 int slots_to_fill
, int *pslots_filled
,
994 bool *pannul_p
, rtx
*pnew_thread
)
996 int slots_remaining
= slots_to_fill
- *pslots_filled
;
997 int total_slots_filled
= *pslots_filled
;
998 auto_vec
<rtx_insn
*, 5> new_delay_list
;
999 bool must_annul
= *pannul_p
;
1000 bool used_annul
= false;
1002 struct resources cc_set
;
1003 rtx_insn
**redundant
;
1005 /* We can't do anything if there are more delay slots in SEQ than we
1006 can handle, or if we don't know that it will be a taken branch.
1007 We know that it will be a taken branch if it is either an unconditional
1008 branch or a conditional branch with a stricter branch condition.
1010 Also, exit if the branch has more than one set, since then it is computing
1011 other results that can't be ignored, e.g. the HPPA mov&branch instruction.
1012 ??? It may be possible to move other sets into INSN in addition to
1013 moving the instructions in the delay slots.
1015 We cannot steal the delay list if one of the instructions in the
1016 current delay_list modifies the condition codes and the jump in the
1017 sequence is a conditional jump. We cannot do this because we cannot
1018 change the direction of the jump because the condition codes
1019 will effect the direction of the jump in the sequence. */
1021 CLEAR_RESOURCE (&cc_set
);
1024 FOR_EACH_VEC_ELT (*delay_list
, i
, trial
)
1026 mark_set_resources (trial
, &cc_set
, 0, MARK_SRC_DEST_CALL
);
1027 if (insn_references_resource_p (seq
->insn (0), &cc_set
, false))
1031 if (XVECLEN (seq
, 0) - 1 > slots_remaining
1032 || ! condition_dominates_p (condition
, seq
->insn (0))
1033 || ! single_set (seq
->insn (0)))
1036 /* On some targets, branches with delay slots can have a limited
1037 displacement. Give the back end a chance to tell us we can't do
1039 if (! targetm
.can_follow_jump (insn
, seq
->insn (0)))
1042 redundant
= XALLOCAVEC (rtx_insn
*, XVECLEN (seq
, 0));
1043 for (i
= 1; i
< seq
->len (); i
++)
1045 rtx_insn
*trial
= seq
->insn (i
);
1048 if (insn_references_resource_p (trial
, sets
, false)
1049 || insn_sets_resource_p (trial
, needed
, false)
1050 || insn_sets_resource_p (trial
, sets
, false)
1051 /* If TRIAL is from the fallthrough code of an annulled branch insn
1052 in SEQ, we cannot use it. */
1053 || (INSN_ANNULLED_BRANCH_P (seq
->insn (0))
1054 && ! INSN_FROM_TARGET_P (trial
)))
1057 /* If this insn was already done (usually in a previous delay slot),
1058 pretend we put it in our delay slot. */
1059 redundant
[i
] = redundant_insn (trial
, insn
, new_delay_list
);
1063 /* We will end up re-vectoring this branch, so compute flags
1064 based on jumping to the new label. */
1065 flags
= get_jump_flags (insn
, JUMP_LABEL (seq
->insn (0)));
1068 && ((condition
== const_true_rtx
1069 || (! insn_sets_resource_p (trial
, other_needed
, false)
1070 && ! may_trap_or_fault_p (PATTERN (trial
)))))
1071 ? eligible_for_delay (insn
, total_slots_filled
, trial
, flags
)
1072 : (must_annul
|| (delay_list
->is_empty () && new_delay_list
.is_empty ()))
1073 && (must_annul
= true,
1074 check_annul_list_true_false (false, *delay_list
)
1075 && check_annul_list_true_false (false, new_delay_list
)
1076 && eligible_for_annul_false (insn
, total_slots_filled
,
1081 /* Frame related instructions cannot go into annulled delay
1082 slots, it messes up the dwarf info. */
1083 if (RTX_FRAME_RELATED_P (trial
))
1087 rtx_insn
*temp
= copy_delay_slot_insn (trial
);
1088 INSN_FROM_TARGET_P (temp
) = 1;
1089 add_to_delay_list (temp
, &new_delay_list
);
1090 total_slots_filled
++;
1092 if (--slots_remaining
== 0)
1099 /* Record the effect of the instructions that were redundant and which
1100 we therefore decided not to copy. */
1101 for (i
= 1; i
< seq
->len (); i
++)
1104 fix_reg_dead_note (redundant
[i
], insn
);
1105 update_block (seq
->insn (i
), insn
);
1108 /* Show the place to which we will be branching. */
1109 *pnew_thread
= first_active_target_insn (JUMP_LABEL (seq
->insn (0)));
1111 /* Add any new insns to the delay list and update the count of the
1112 number of slots filled. */
1113 *pslots_filled
= total_slots_filled
;
1118 FOR_EACH_VEC_ELT (new_delay_list
, i
, temp
)
1119 add_to_delay_list (temp
, delay_list
);
1122 /* Similar to steal_delay_list_from_target except that SEQ is on the
1123 fallthrough path of INSN. Here we only do something if the delay insn
1124 of SEQ is an unconditional branch. In that case we steal its delay slot
1125 for INSN since unconditional branches are much easier to fill. */
1128 steal_delay_list_from_fallthrough (rtx_insn
*insn
, rtx condition
,
1130 vec
<rtx_insn
*> *delay_list
,
1131 struct resources
*sets
,
1132 struct resources
*needed
,
1133 struct resources
*other_needed
,
1134 int slots_to_fill
, int *pslots_filled
,
1139 bool must_annul
= *pannul_p
;
1140 bool used_annul
= false;
1142 flags
= get_jump_flags (insn
, JUMP_LABEL (insn
));
1144 /* We can't do anything if SEQ's delay insn isn't an
1145 unconditional branch. */
1147 if (! simplejump_or_return_p (seq
->insn (0)))
1150 for (i
= 1; i
< seq
->len (); i
++)
1152 rtx_insn
*trial
= seq
->insn (i
);
1153 rtx_insn
*prior_insn
;
1155 if (insn_references_resource_p (trial
, sets
, false)
1156 || insn_sets_resource_p (trial
, needed
, false)
1157 || insn_sets_resource_p (trial
, sets
, false))
1160 /* If this insn was already done, we don't need it. */
1161 if ((prior_insn
= redundant_insn (trial
, insn
, *delay_list
)))
1163 fix_reg_dead_note (prior_insn
, insn
);
1164 update_block (trial
, insn
);
1165 delete_from_delay_slot (trial
);
1170 && ((condition
== const_true_rtx
1171 || (! insn_sets_resource_p (trial
, other_needed
, false)
1172 && ! may_trap_or_fault_p (PATTERN (trial
)))))
1173 ? eligible_for_delay (insn
, *pslots_filled
, trial
, flags
)
1174 : (must_annul
|| delay_list
->is_empty ()) && (must_annul
= true,
1175 check_annul_list_true_false (true, *delay_list
)
1176 && eligible_for_annul_true (insn
, *pslots_filled
, trial
, flags
)))
1180 delete_from_delay_slot (trial
);
1181 add_to_delay_list (trial
, delay_list
);
1183 if (++(*pslots_filled
) == slots_to_fill
)
1194 /* Try merging insns starting at THREAD which match exactly the insns in
1197 If all insns were matched and the insn was previously annulling, the
1198 annul bit will be cleared.
1200 For each insn that is merged, if the branch is or will be non-annulling,
1201 we delete the merged insn. */
1204 try_merge_delay_insns (rtx_insn
*insn
, rtx_insn
*thread
)
1206 rtx_insn
*trial
, *next_trial
;
1207 rtx_insn
*delay_insn
= as_a
<rtx_insn
*> (XVECEXP (PATTERN (insn
), 0, 0));
1208 bool annul_p
= JUMP_P (delay_insn
) && INSN_ANNULLED_BRANCH_P (delay_insn
);
1209 int slot_number
= 1;
1210 int num_slots
= XVECLEN (PATTERN (insn
), 0);
1211 rtx next_to_match
= XVECEXP (PATTERN (insn
), 0, slot_number
);
1212 struct resources set
, needed
, modified
;
1213 auto_vec
<std::pair
<rtx_insn
*, bool>, 10> merged_insns
;
1216 flags
= get_jump_flags (delay_insn
, JUMP_LABEL (delay_insn
));
1218 CLEAR_RESOURCE (&needed
);
1219 CLEAR_RESOURCE (&set
);
1221 /* If this is not an annulling branch, take into account anything needed in
1222 INSN's delay slot. This prevents two increments from being incorrectly
1223 folded into one. If we are annulling, this would be the correct
1224 thing to do. (The alternative, looking at things set in NEXT_TO_MATCH
1225 will essentially disable this optimization. This method is somewhat of
1226 a kludge, but I don't see a better way.) */
1228 for (int i
= 1; i
< num_slots
; i
++)
1229 if (XVECEXP (PATTERN (insn
), 0, i
))
1230 mark_referenced_resources (XVECEXP (PATTERN (insn
), 0, i
), &needed
,
1233 for (trial
= thread
; !stop_search_p (trial
, true); trial
= next_trial
)
1235 rtx pat
= PATTERN (trial
);
1236 rtx oldtrial
= trial
;
1238 next_trial
= next_nonnote_insn (trial
);
1240 /* TRIAL must be a CALL_INSN or INSN. Skip USE and CLOBBER. */
1241 if (NONJUMP_INSN_P (trial
)
1242 && (GET_CODE (pat
) == USE
|| GET_CODE (pat
) == CLOBBER
))
1245 if (GET_CODE (next_to_match
) == GET_CODE (trial
)
1246 && ! insn_references_resource_p (trial
, &set
, true)
1247 && ! insn_sets_resource_p (trial
, &set
, true)
1248 && ! insn_sets_resource_p (trial
, &needed
, true)
1249 && (trial
= try_split (pat
, trial
, 0)) != 0
1250 /* Update next_trial, in case try_split succeeded. */
1251 && (next_trial
= next_nonnote_insn (trial
))
1252 /* Likewise THREAD. */
1253 && (thread
= oldtrial
== thread
? trial
: thread
)
1254 && rtx_equal_p (PATTERN (next_to_match
), PATTERN (trial
))
1255 /* Have to test this condition if annul condition is different
1256 from (and less restrictive than) non-annulling one. */
1257 && eligible_for_delay (delay_insn
, slot_number
- 1, trial
, flags
))
1262 update_block (trial
, thread
);
1263 if (trial
== thread
)
1264 thread
= next_active_insn (thread
);
1266 delete_related_insns (trial
);
1267 INSN_FROM_TARGET_P (next_to_match
) = 0;
1270 merged_insns
.safe_push (std::pair
<rtx_insn
*, bool> (trial
, false));
1272 if (++slot_number
== num_slots
)
1275 next_to_match
= XVECEXP (PATTERN (insn
), 0, slot_number
);
1278 mark_set_resources (trial
, &set
, 0, MARK_SRC_DEST_CALL
);
1279 mark_referenced_resources (trial
, &needed
, true);
1282 /* See if we stopped on a filled insn. If we did, try to see if its
1283 delay slots match. */
1284 if (slot_number
!= num_slots
1285 && trial
&& NONJUMP_INSN_P (trial
)
1286 && GET_CODE (PATTERN (trial
)) == SEQUENCE
1287 && !(JUMP_P (XVECEXP (PATTERN (trial
), 0, 0))
1288 && INSN_ANNULLED_BRANCH_P (XVECEXP (PATTERN (trial
), 0, 0))))
1290 rtx_sequence
*pat
= as_a
<rtx_sequence
*> (PATTERN (trial
));
1291 rtx filled_insn
= XVECEXP (pat
, 0, 0);
1293 /* Account for resources set/needed by the filled insn. */
1294 mark_set_resources (filled_insn
, &set
, 0, MARK_SRC_DEST_CALL
);
1295 mark_referenced_resources (filled_insn
, &needed
, true);
1297 for (int i
= 1; i
< pat
->len (); i
++)
1299 rtx_insn
*dtrial
= pat
->insn (i
);
1301 CLEAR_RESOURCE (&modified
);
1302 /* Account for resources set by the insn following NEXT_TO_MATCH
1303 inside INSN's delay list. */
1304 for (int j
= 1; slot_number
+ j
< num_slots
; j
++)
1305 mark_set_resources (XVECEXP (PATTERN (insn
), 0, slot_number
+ j
),
1306 &modified
, 0, MARK_SRC_DEST_CALL
);
1307 /* Account for resources set by the insn before DTRIAL and inside
1308 TRIAL's delay list. */
1309 for (int j
= 1; j
< i
; j
++)
1310 mark_set_resources (XVECEXP (pat
, 0, j
),
1311 &modified
, 0, MARK_SRC_DEST_CALL
);
1312 if (! insn_references_resource_p (dtrial
, &set
, true)
1313 && ! insn_sets_resource_p (dtrial
, &set
, true)
1314 && ! insn_sets_resource_p (dtrial
, &needed
, true)
1315 && rtx_equal_p (PATTERN (next_to_match
), PATTERN (dtrial
))
1316 /* Check that DTRIAL and NEXT_TO_MATCH does not reference a
1317 resource modified between them (only dtrial is checked because
1318 next_to_match and dtrial shall to be equal in order to hit
1320 && ! insn_references_resource_p (dtrial
, &modified
, true)
1321 && eligible_for_delay (delay_insn
, slot_number
- 1, dtrial
, flags
))
1327 update_block (dtrial
, thread
);
1328 new_rtx
= delete_from_delay_slot (dtrial
);
1329 if (thread
->deleted ())
1331 INSN_FROM_TARGET_P (next_to_match
) = 0;
1334 merged_insns
.safe_push (std::pair
<rtx_insn
*, bool> (dtrial
,
1337 if (++slot_number
== num_slots
)
1340 next_to_match
= XVECEXP (PATTERN (insn
), 0, slot_number
);
1344 /* Keep track of the set/referenced resources for the delay
1345 slots of any trial insns we encounter. */
1346 mark_set_resources (dtrial
, &set
, 0, MARK_SRC_DEST_CALL
);
1347 mark_referenced_resources (dtrial
, &needed
, true);
1352 /* If all insns in the delay slot have been matched and we were previously
1353 annulling the branch, we need not any more. In that case delete all the
1354 merged insns. Also clear the INSN_FROM_TARGET_P bit of each insn in
1355 the delay list so that we know that it isn't only being used at the
1357 if (slot_number
== num_slots
&& annul_p
)
1359 unsigned int len
= merged_insns
.length ();
1360 for (unsigned int i
= len
- 1; i
< len
; i
--)
1361 if (merged_insns
[i
].second
)
1363 update_block (merged_insns
[i
].first
, thread
);
1364 rtx_insn
*new_rtx
= delete_from_delay_slot (merged_insns
[i
].first
);
1365 if (thread
->deleted ())
1370 update_block (merged_insns
[i
].first
, thread
);
1371 delete_related_insns (merged_insns
[i
].first
);
1374 INSN_ANNULLED_BRANCH_P (delay_insn
) = 0;
1376 for (int i
= 0; i
< XVECLEN (PATTERN (insn
), 0); i
++)
1377 INSN_FROM_TARGET_P (XVECEXP (PATTERN (insn
), 0, i
)) = 0;
1381 /* See if INSN is redundant with an insn in front of TARGET. Often this
1382 is called when INSN is a candidate for a delay slot of TARGET.
1383 DELAY_LIST are insns that will be placed in delay slots of TARGET in front
1384 of INSN. Often INSN will be redundant with an insn in a delay slot of
1385 some previous insn. This happens when we have a series of branches to the
1386 same label; in that case the first insn at the target might want to go
1387 into each of the delay slots.
1389 If we are not careful, this routine can take up a significant fraction
1390 of the total compilation time (4%), but only wins rarely. Hence we
1391 speed this routine up by making two passes. The first pass goes back
1392 until it hits a label and sees if it finds an insn with an identical
1393 pattern. Only in this (relatively rare) event does it check for
1396 We do not split insns we encounter. This could cause us not to find a
1397 redundant insn, but the cost of splitting seems greater than the possible
1398 gain in rare cases. */
1401 redundant_insn (rtx insn
, rtx_insn
*target
, const vec
<rtx_insn
*> &delay_list
)
1403 rtx target_main
= target
;
1404 rtx ipat
= PATTERN (insn
);
1407 struct resources needed
, set
;
1409 unsigned insns_to_search
;
1411 /* If INSN has any REG_UNUSED notes, it can't match anything since we
1412 are allowed to not actually assign to such a register. */
1413 if (find_reg_note (insn
, REG_UNUSED
, NULL_RTX
) != 0)
1416 /* Scan backwards looking for a match. */
1417 for (trial
= PREV_INSN (target
),
1418 insns_to_search
= param_max_delay_slot_insn_search
;
1419 trial
&& insns_to_search
> 0;
1420 trial
= PREV_INSN (trial
))
1422 /* (use (insn))s can come immediately after a barrier if the
1423 label that used to precede them has been deleted as dead.
1424 See delete_related_insns. */
1425 if (LABEL_P (trial
) || BARRIER_P (trial
))
1428 if (!INSN_P (trial
))
1432 pat
= PATTERN (trial
);
1433 if (GET_CODE (pat
) == USE
|| GET_CODE (pat
) == CLOBBER
)
1436 if (GET_CODE (trial
) == DEBUG_INSN
)
1439 if (rtx_sequence
*seq
= dyn_cast
<rtx_sequence
*> (pat
))
1441 /* Stop for a CALL and its delay slots because it is difficult to
1442 track its resource needs correctly. */
1443 if (CALL_P (seq
->element (0)))
1446 /* Stop for an INSN or JUMP_INSN with delayed effects and its delay
1447 slots because it is difficult to track its resource needs
1450 if (INSN_SETS_ARE_DELAYED (seq
->insn (0)))
1453 if (INSN_REFERENCES_ARE_DELAYED (seq
->insn (0)))
1456 /* See if any of the insns in the delay slot match, updating
1457 resource requirements as we go. */
1458 for (i
= seq
->len () - 1; i
> 0; i
--)
1459 if (GET_CODE (seq
->element (i
)) == GET_CODE (insn
)
1460 && rtx_equal_p (PATTERN (seq
->element (i
)), ipat
)
1461 && ! find_reg_note (seq
->element (i
), REG_UNUSED
, NULL_RTX
))
1464 /* If found a match, exit this loop early. */
1469 else if (GET_CODE (trial
) == GET_CODE (insn
) && rtx_equal_p (pat
, ipat
)
1470 && ! find_reg_note (trial
, REG_UNUSED
, NULL_RTX
))
1474 /* If we didn't find an insn that matches, return 0. */
1478 /* See what resources this insn sets and needs. If they overlap, it
1479 can't be redundant. */
1481 CLEAR_RESOURCE (&needed
);
1482 CLEAR_RESOURCE (&set
);
1483 mark_set_resources (insn
, &set
, 0, MARK_SRC_DEST_CALL
);
1484 mark_referenced_resources (insn
, &needed
, true);
1486 /* If TARGET is a SEQUENCE, get the main insn. */
1487 if (NONJUMP_INSN_P (target
) && GET_CODE (PATTERN (target
)) == SEQUENCE
)
1488 target_main
= XVECEXP (PATTERN (target
), 0, 0);
1490 if (resource_conflicts_p (&needed
, &set
)
1491 /* The insn requiring the delay may not set anything needed or set by
1493 || insn_sets_resource_p (target_main
, &needed
, true)
1494 || insn_sets_resource_p (target_main
, &set
, true))
1497 /* Insns we pass may not set either NEEDED or SET, so merge them for
1499 needed
.memory
|= set
.memory
;
1500 needed
.regs
|= set
.regs
;
1502 /* This insn isn't redundant if it conflicts with an insn that either is
1503 or will be in a delay slot of TARGET. */
1507 FOR_EACH_VEC_ELT (delay_list
, j
, temp
)
1508 if (insn_sets_resource_p (temp
, &needed
, true))
1511 if (NONJUMP_INSN_P (target
) && GET_CODE (PATTERN (target
)) == SEQUENCE
)
1512 for (i
= 1; i
< XVECLEN (PATTERN (target
), 0); i
++)
1513 if (insn_sets_resource_p (XVECEXP (PATTERN (target
), 0, i
), &needed
,
1517 /* Scan backwards until we reach a label or an insn that uses something
1518 INSN sets or sets something insn uses or sets. */
1520 for (trial
= PREV_INSN (target
),
1521 insns_to_search
= param_max_delay_slot_insn_search
;
1522 trial
&& !LABEL_P (trial
) && insns_to_search
> 0;
1523 trial
= PREV_INSN (trial
))
1525 if (!INSN_P (trial
))
1529 pat
= PATTERN (trial
);
1530 if (GET_CODE (pat
) == USE
|| GET_CODE (pat
) == CLOBBER
)
1533 if (GET_CODE (trial
) == DEBUG_INSN
)
1536 if (rtx_sequence
*seq
= dyn_cast
<rtx_sequence
*> (pat
))
1538 bool annul_p
= false;
1539 rtx_insn
*control
= seq
->insn (0);
1541 /* If this is a CALL_INSN and its delay slots, it is hard to track
1542 the resource needs properly, so give up. */
1543 if (CALL_P (control
))
1546 /* If this is an INSN or JUMP_INSN with delayed effects, it
1547 is hard to track the resource needs properly, so give up. */
1549 if (INSN_SETS_ARE_DELAYED (control
))
1552 if (INSN_REFERENCES_ARE_DELAYED (control
))
1555 if (JUMP_P (control
))
1556 annul_p
= INSN_ANNULLED_BRANCH_P (control
);
1558 /* See if any of the insns in the delay slot match, updating
1559 resource requirements as we go. */
1560 for (i
= seq
->len () - 1; i
> 0; i
--)
1562 rtx_insn
*candidate
= seq
->insn (i
);
1564 /* If an insn will be annulled if the branch is false, it isn't
1565 considered as a possible duplicate insn. */
1566 if (rtx_equal_p (PATTERN (candidate
), ipat
)
1567 && ! (annul_p
&& INSN_FROM_TARGET_P (candidate
)))
1569 /* Show that this insn will be used in the sequel. */
1570 INSN_FROM_TARGET_P (candidate
) = 0;
1574 /* Unless this is an annulled insn from the target of a branch,
1575 we must stop if it sets anything needed or set by INSN. */
1576 if ((!annul_p
|| !INSN_FROM_TARGET_P (candidate
))
1577 && insn_sets_resource_p (candidate
, &needed
, true))
1581 /* If the insn requiring the delay slot conflicts with INSN, we
1583 if (insn_sets_resource_p (control
, &needed
, true))
1588 /* See if TRIAL is the same as INSN. */
1589 pat
= PATTERN (trial
);
1590 if (rtx_equal_p (pat
, ipat
))
1593 /* Can't go any further if TRIAL conflicts with INSN. */
1594 if (insn_sets_resource_p (trial
, &needed
, true))
1602 /* Return true if THREAD can only be executed in one way. If LABEL is nonzero,
1603 it is the target of the branch insn being scanned. If ALLOW_FALLTHROUGH
1604 is true, we are allowed to fall into this thread; otherwise, we are not.
1606 If LABEL is used more than one or we pass a label other than LABEL before
1607 finding an active insn, we do not own this thread. */
1610 own_thread_p (rtx thread
, rtx label
, bool allow_fallthrough
)
1612 rtx_insn
*active_insn
;
1615 /* We don't own the function end. */
1616 if (thread
== 0 || ANY_RETURN_P (thread
))
1619 /* We have a non-NULL insn. */
1620 rtx_insn
*thread_insn
= as_a
<rtx_insn
*> (thread
);
1622 /* Get the first active insn, or THREAD_INSN, if it is an active insn. */
1623 active_insn
= next_active_insn (PREV_INSN (thread_insn
));
1625 for (insn
= thread_insn
; insn
!= active_insn
; insn
= NEXT_INSN (insn
))
1627 && (insn
!= label
|| LABEL_NUSES (insn
) != 1))
1630 if (allow_fallthrough
)
1633 /* Ensure that we reach a BARRIER before any insn or label. */
1634 for (insn
= prev_nonnote_insn (thread_insn
);
1635 insn
== 0 || !BARRIER_P (insn
);
1636 insn
= prev_nonnote_insn (insn
))
1639 || (NONJUMP_INSN_P (insn
)
1640 && GET_CODE (PATTERN (insn
)) != USE
1641 && GET_CODE (PATTERN (insn
)) != CLOBBER
))
1647 /* Called when INSN is being moved from a location near the target of a jump.
1648 We leave a marker of the form (use (INSN)) immediately in front of WHERE
1649 for mark_target_live_regs. These markers will be deleted at the end.
1651 We used to try to update the live status of registers if WHERE is at
1652 the start of a basic block, but that can't work since we may remove a
1653 BARRIER in relax_delay_slots. */
1656 update_block (rtx_insn
*insn
, rtx_insn
*where
)
1658 emit_insn_before (gen_rtx_USE (VOIDmode
, insn
), where
);
1660 /* INSN might be making a value live in a block where it didn't use to
1661 be. So recompute liveness information for this block. */
1662 incr_ticks_for_insn (insn
);
1665 /* Similar to REDIRECT_JUMP except that we update the BB_TICKS entry for
1666 the basic block containing the jump. */
1669 reorg_redirect_jump (rtx_jump_insn
*jump
, rtx nlabel
)
1671 incr_ticks_for_insn (jump
);
1672 return redirect_jump (jump
, nlabel
, 1);
1675 /* Called when INSN is being moved forward into a delay slot of DELAYED_INSN.
1676 We check every instruction between INSN and DELAYED_INSN for REG_DEAD notes
1677 that reference values used in INSN. If we find one, then we move the
1678 REG_DEAD note to INSN.
1680 This is needed to handle the case where a later insn (after INSN) has a
1681 REG_DEAD note for a register used by INSN, and this later insn subsequently
1682 gets moved before a CODE_LABEL because it is a redundant insn. In this
1683 case, mark_target_live_regs may be confused into thinking the register
1684 is dead because it sees a REG_DEAD note immediately before a CODE_LABEL. */
1687 update_reg_dead_notes (rtx_insn
*insn
, rtx_insn
*delayed_insn
)
1692 for (p
= next_nonnote_insn (insn
); p
!= delayed_insn
;
1693 p
= next_nonnote_insn (p
))
1694 for (link
= REG_NOTES (p
); link
; link
= next
)
1696 next
= XEXP (link
, 1);
1698 if (REG_NOTE_KIND (link
) != REG_DEAD
1699 || !REG_P (XEXP (link
, 0)))
1702 if (reg_referenced_p (XEXP (link
, 0), PATTERN (insn
)))
1704 /* Move the REG_DEAD note from P to INSN. */
1705 remove_note (p
, link
);
1706 XEXP (link
, 1) = REG_NOTES (insn
);
1707 REG_NOTES (insn
) = link
;
1712 /* Called when an insn redundant with start_insn is deleted. If there
1713 is a REG_DEAD note for the target of start_insn between start_insn
1714 and stop_insn, then the REG_DEAD note needs to be deleted since the
1715 value no longer dies there.
1717 If the REG_DEAD note isn't deleted, then mark_target_live_regs may be
1718 confused into thinking the register is dead. */
1721 fix_reg_dead_note (rtx_insn
*start_insn
, rtx stop_insn
)
1726 for (p
= next_nonnote_insn (start_insn
); p
!= stop_insn
;
1727 p
= next_nonnote_insn (p
))
1728 for (link
= REG_NOTES (p
); link
; link
= next
)
1730 next
= XEXP (link
, 1);
1732 if (REG_NOTE_KIND (link
) != REG_DEAD
1733 || !REG_P (XEXP (link
, 0)))
1736 if (reg_set_p (XEXP (link
, 0), PATTERN (start_insn
)))
1738 remove_note (p
, link
);
1744 /* Delete any REG_UNUSED notes that exist on INSN but not on OTHER_INSN.
1746 This handles the case of udivmodXi4 instructions which optimize their
1747 output depending on whether any REG_UNUSED notes are present. We must
1748 make sure that INSN calculates as many results as OTHER_INSN does. */
1751 update_reg_unused_notes (rtx_insn
*insn
, rtx other_insn
)
1755 for (link
= REG_NOTES (insn
); link
; link
= next
)
1757 next
= XEXP (link
, 1);
1759 if (REG_NOTE_KIND (link
) != REG_UNUSED
1760 || !REG_P (XEXP (link
, 0)))
1763 if (!find_regno_note (other_insn
, REG_UNUSED
, REGNO (XEXP (link
, 0))))
1764 remove_note (insn
, link
);
1768 static vec
<rtx
> sibling_labels
;
1770 /* Return the label before INSN, or put a new label there. If SIBLING is
1771 non-zero, it is another label associated with the new label (if any),
1772 typically the former target of the jump that will be redirected to
1776 get_label_before (rtx_insn
*insn
, rtx sibling
)
1780 /* Find an existing label at this point
1781 or make a new one if there is none. */
1782 label
= prev_nonnote_insn (insn
);
1784 if (label
== 0 || !LABEL_P (label
))
1786 rtx_insn
*prev
= PREV_INSN (insn
);
1788 label
= gen_label_rtx ();
1789 emit_label_after (label
, prev
);
1790 LABEL_NUSES (label
) = 0;
1793 sibling_labels
.safe_push (label
);
1794 sibling_labels
.safe_push (sibling
);
1800 /* Scan a function looking for insns that need a delay slot and find insns to
1801 put into the delay slot.
1803 NON_JUMPS_P is true if we are to only try to fill non-jump insns (such
1804 as calls). We do these first since we don't want jump insns (that are
1805 easier to fill) to get the only insns that could be used for non-jump insns.
1806 When it is zero, only try to fill JUMP_INSNs.
1808 When slots are filled in this manner, the insns (including the
1809 delay_insn) are put together in a SEQUENCE rtx. In this fashion,
1810 it is possible to tell whether a delay slot has really been filled
1811 or not. `final' knows how to deal with this, by communicating
1812 through FINAL_SEQUENCE. */
1815 fill_simple_delay_slots (bool non_jumps_p
)
1817 rtx_insn
*insn
, *trial
, *next_trial
;
1820 int num_unfilled_slots
= unfilled_slots_next
- unfilled_slots_base
;
1821 struct resources needed
, set
;
1822 int slots_to_fill
, slots_filled
;
1823 auto_vec
<rtx_insn
*, 5> delay_list
;
1825 for (i
= 0; i
< num_unfilled_slots
; i
++)
1828 /* Get the next insn to fill. If it has already had any slots assigned,
1829 we can't do anything with it. Maybe we'll improve this later. */
1831 insn
= unfilled_slots_base
[i
];
1834 || (NONJUMP_INSN_P (insn
)
1835 && GET_CODE (PATTERN (insn
)) == SEQUENCE
)
1836 || (JUMP_P (insn
) && non_jumps_p
)
1837 || (!JUMP_P (insn
) && ! non_jumps_p
))
1840 /* It may have been that this insn used to need delay slots, but
1841 now doesn't; ignore in that case. This can happen, for example,
1842 on the HP PA RISC, where the number of delay slots depends on
1843 what insns are nearby. */
1844 slots_to_fill
= num_delay_slots (insn
);
1846 /* Some machine description have defined instructions to have
1847 delay slots only in certain circumstances which may depend on
1848 nearby insns (which change due to reorg's actions).
1850 For example, the PA port normally has delay slots for unconditional
1853 However, the PA port claims such jumps do not have a delay slot
1854 if they are immediate successors of certain CALL_INSNs. This
1855 allows the port to favor filling the delay slot of the call with
1856 the unconditional jump. */
1857 if (slots_to_fill
== 0)
1860 /* This insn needs, or can use, some delay slots. SLOTS_TO_FILL
1861 says how many. After initialization, first try optimizing
1864 nop add %o7,.-L1,%o7
1868 If this case applies, the delay slot of the call is filled with
1869 the unconditional jump. This is done first to avoid having the
1870 delay slot of the call filled in the backward scan. Also, since
1871 the unconditional jump is likely to also have a delay slot, that
1872 insn must exist when it is subsequently scanned.
1874 This is tried on each insn with delay slots as some machines
1875 have insns which perform calls, but are not represented as
1879 delay_list
.truncate (0);
1882 flags
= get_jump_flags (insn
, JUMP_LABEL (insn
));
1884 flags
= get_jump_flags (insn
, NULL_RTX
);
1886 if ((trial
= next_active_insn (insn
))
1888 && simplejump_p (trial
)
1889 && eligible_for_delay (insn
, slots_filled
, trial
, flags
)
1890 && no_labels_between_p (insn
, trial
)
1891 && ! can_throw_internal (trial
))
1895 add_to_delay_list (trial
, &delay_list
);
1897 /* TRIAL may have had its delay slot filled, then unfilled. When
1898 the delay slot is unfilled, TRIAL is placed back on the unfilled
1899 slots obstack. Unfortunately, it is placed on the end of the
1900 obstack, not in its original location. Therefore, we must search
1901 from entry i + 1 to the end of the unfilled slots obstack to
1902 try and find TRIAL. */
1903 tmp
= &unfilled_slots_base
[i
+ 1];
1904 while (*tmp
!= trial
&& tmp
!= unfilled_slots_next
)
1907 /* Remove the unconditional jump from consideration for delay slot
1908 filling and unthread it. */
1912 rtx_insn
*next
= NEXT_INSN (trial
);
1913 rtx_insn
*prev
= PREV_INSN (trial
);
1915 SET_NEXT_INSN (prev
) = next
;
1917 SET_PREV_INSN (next
) = prev
;
1921 /* Now, scan backwards from the insn to search for a potential
1922 delay-slot candidate. Stop searching when a label or jump is hit.
1924 For each candidate, if it is to go into the delay slot (moved
1925 forward in execution sequence), it must not need or set any resources
1926 that were set by later insns and must not set any resources that
1927 are needed for those insns.
1929 The delay slot insn itself sets resources unless it is a call
1930 (in which case the called routine, not the insn itself, is doing
1933 if (slots_filled
< slots_to_fill
)
1935 /* If the flags register is dead after the insn, then we want to be
1936 able to accept a candidate that clobbers it. For this purpose,
1937 we need to filter the flags register during life analysis, so
1938 that it doesn't create RAW and WAW dependencies, while still
1939 creating the necessary WAR dependencies. */
1941 = (slots_to_fill
== 1
1942 && targetm
.flags_regnum
!= INVALID_REGNUM
1943 && find_regno_note (insn
, REG_DEAD
, targetm
.flags_regnum
));
1944 struct resources fset
;
1945 CLEAR_RESOURCE (&needed
);
1946 CLEAR_RESOURCE (&set
);
1947 mark_set_resources (insn
, &set
, 0, MARK_SRC_DEST
);
1950 CLEAR_RESOURCE (&fset
);
1951 mark_set_resources (insn
, &fset
, 0, MARK_SRC_DEST
);
1953 mark_referenced_resources (insn
, &needed
, false);
1955 for (trial
= prev_nonnote_insn (insn
); ! stop_search_p (trial
, true);
1958 next_trial
= prev_nonnote_insn (trial
);
1960 /* This must be an INSN or CALL_INSN. */
1961 pat
= PATTERN (trial
);
1963 /* Stand-alone USE and CLOBBER are just for flow. */
1964 if (GET_CODE (pat
) == USE
|| GET_CODE (pat
) == CLOBBER
)
1967 /* And DEBUG_INSNs never go into delay slots. */
1968 if (GET_CODE (trial
) == DEBUG_INSN
)
1971 /* Check for resource conflict first, to avoid unnecessary
1973 if (! insn_references_resource_p (trial
, &set
, true)
1974 && ! insn_sets_resource_p (trial
,
1975 filter_flags
? &fset
: &set
,
1977 && ! insn_sets_resource_p (trial
, &needed
, true)
1978 && ! can_throw_internal (trial
))
1980 trial
= try_split (pat
, trial
, 1);
1981 next_trial
= prev_nonnote_insn (trial
);
1982 if (eligible_for_delay (insn
, slots_filled
, trial
, flags
))
1984 /* In this case, we are searching backward, so if we
1985 find insns to put on the delay list, we want
1986 to put them at the head, rather than the
1987 tail, of the list. */
1989 update_reg_dead_notes (trial
, insn
);
1990 delay_list
.safe_insert (0, trial
);
1991 update_block (trial
, trial
);
1992 delete_related_insns (trial
);
1993 if (slots_to_fill
== ++slots_filled
)
1999 mark_set_resources (trial
, &set
, 0, MARK_SRC_DEST_CALL
);
2002 mark_set_resources (trial
, &fset
, 0, MARK_SRC_DEST_CALL
);
2003 /* If the flags register is set, then it doesn't create RAW
2004 dependencies any longer and it also doesn't create WAW
2005 dependencies since it's dead after the original insn. */
2006 if (TEST_HARD_REG_BIT (fset
.regs
, targetm
.flags_regnum
))
2008 CLEAR_HARD_REG_BIT (needed
.regs
, targetm
.flags_regnum
);
2009 CLEAR_HARD_REG_BIT (fset
.regs
, targetm
.flags_regnum
);
2012 mark_referenced_resources (trial
, &needed
, true);
2016 /* If all needed slots haven't been filled, we come here. */
2018 /* Try to optimize case of jumping around a single insn. */
2019 if ((ANNUL_IFTRUE_SLOTS
|| ANNUL_IFFALSE_SLOTS
)
2020 && slots_filled
!= slots_to_fill
2021 && delay_list
.is_empty ()
2023 && (condjump_p (insn
) || condjump_in_parallel_p (insn
))
2024 && !ANY_RETURN_P (JUMP_LABEL (insn
)))
2026 optimize_skip (as_a
<rtx_jump_insn
*> (insn
), &delay_list
);
2027 if (!delay_list
.is_empty ())
2031 /* Try to get insns from beyond the insn needing the delay slot.
2032 These insns can neither set or reference resources set in insns being
2033 skipped, cannot set resources in the insn being skipped, and, if this
2034 is a CALL_INSN (or a CALL_INSN is passed), cannot trap (because the
2035 call might not return).
2037 There used to be code which continued past the target label if
2038 we saw all uses of the target label. This code did not work,
2039 because it failed to account for some instructions which were
2040 both annulled and marked as from the target. This can happen as a
2041 result of optimize_skip. Since this code was redundant with
2042 fill_eager_delay_slots anyways, it was just deleted. */
2044 if (slots_filled
!= slots_to_fill
2045 /* If this instruction could throw an exception which is
2046 caught in the same function, then it's not safe to fill
2047 the delay slot with an instruction from beyond this
2048 point. For example, consider:
2059 Even though `i' is a local variable, we must be sure not
2060 to put `i = 3' in the delay slot if `f' might throw an
2063 Presumably, we should also check to see if we could get
2064 back to this function via `setjmp'. */
2065 && ! can_throw_internal (insn
)
2068 bool maybe_never
= false;
2069 rtx pat
, trial_delay
;
2071 CLEAR_RESOURCE (&needed
);
2072 CLEAR_RESOURCE (&set
);
2073 mark_set_resources (insn
, &set
, 0, MARK_SRC_DEST_CALL
);
2074 mark_referenced_resources (insn
, &needed
, true);
2079 for (trial
= next_nonnote_insn (insn
); !stop_search_p (trial
, true);
2082 next_trial
= next_nonnote_insn (trial
);
2084 /* This must be an INSN or CALL_INSN. */
2085 pat
= PATTERN (trial
);
2087 /* Stand-alone USE and CLOBBER are just for flow. */
2088 if (GET_CODE (pat
) == USE
|| GET_CODE (pat
) == CLOBBER
)
2091 /* And DEBUG_INSNs do not go in delay slots. */
2092 if (GET_CODE (trial
) == DEBUG_INSN
)
2095 /* If this already has filled delay slots, get the insn needing
2097 if (GET_CODE (pat
) == SEQUENCE
)
2098 trial_delay
= XVECEXP (pat
, 0, 0);
2100 trial_delay
= trial
;
2102 /* Stop our search when seeing a jump. */
2103 if (JUMP_P (trial_delay
))
2106 /* See if we have a resource problem before we try to split. */
2107 if (GET_CODE (pat
) != SEQUENCE
2108 && ! insn_references_resource_p (trial
, &set
, true)
2109 && ! insn_sets_resource_p (trial
, &set
, true)
2110 && ! insn_sets_resource_p (trial
, &needed
, true)
2111 && ! (maybe_never
&& may_trap_or_fault_p (pat
))
2112 && (trial
= try_split (pat
, trial
, 0))
2113 && eligible_for_delay (insn
, slots_filled
, trial
, flags
)
2114 && ! can_throw_internal (trial
))
2116 next_trial
= next_nonnote_insn (trial
);
2117 add_to_delay_list (trial
, &delay_list
);
2119 delete_related_insns (trial
);
2120 if (slots_to_fill
== ++slots_filled
)
2125 mark_set_resources (trial
, &set
, 0, MARK_SRC_DEST_CALL
);
2126 mark_referenced_resources (trial
, &needed
, true);
2128 /* Ensure we don't put insns between the setting of cc and the
2129 comparison by moving a setting of cc into an earlier delay
2130 slot since these insns could clobber the condition code. */
2133 /* If this is a call, we might not get here. */
2134 if (CALL_P (trial_delay
))
2138 /* If there are slots left to fill and our search was stopped by an
2139 unconditional branch, try the insn at the branch target. We can
2140 redirect the branch if it works.
2142 Don't do this if the insn at the branch target is a branch. */
2143 if (slots_to_fill
!= slots_filled
2145 && jump_to_label_p (trial
)
2146 && simplejump_p (trial
)
2147 && (next_trial
= next_active_insn (JUMP_LABEL_AS_INSN (trial
))) != 0
2148 && ! (NONJUMP_INSN_P (next_trial
)
2149 && GET_CODE (PATTERN (next_trial
)) == SEQUENCE
)
2150 && !JUMP_P (next_trial
)
2151 && ! insn_references_resource_p (next_trial
, &set
, true)
2152 && ! insn_sets_resource_p (next_trial
, &set
, true)
2153 && ! insn_sets_resource_p (next_trial
, &needed
, true)
2154 && ! (maybe_never
&& may_trap_or_fault_p (PATTERN (next_trial
)))
2155 && (next_trial
= try_split (PATTERN (next_trial
), next_trial
, 0))
2156 && eligible_for_delay (insn
, slots_filled
, next_trial
, flags
)
2157 && ! can_throw_internal (trial
))
2159 /* See comment in relax_delay_slots about necessity of using
2160 next_real_nondebug_insn here. */
2161 rtx_insn
*new_label
= next_real_nondebug_insn (next_trial
);
2164 new_label
= get_label_before (new_label
, JUMP_LABEL (trial
));
2166 new_label
= find_end_label (simple_return_rtx
);
2170 add_to_delay_list (copy_delay_slot_insn (next_trial
),
2173 reorg_redirect_jump (as_a
<rtx_jump_insn
*> (trial
),
2179 /* If this is an unconditional jump, then try to get insns from the
2180 target of the jump. */
2181 rtx_jump_insn
*jump_insn
;
2182 if ((jump_insn
= dyn_cast
<rtx_jump_insn
*> (insn
))
2183 && simplejump_p (jump_insn
)
2184 && slots_filled
!= slots_to_fill
)
2185 fill_slots_from_thread (jump_insn
, const_true_rtx
,
2186 next_active_insn (JUMP_LABEL_AS_INSN (insn
)),
2187 NULL
, 1, 1, own_thread_p (JUMP_LABEL (insn
),
2188 JUMP_LABEL (insn
), false),
2189 slots_to_fill
, &slots_filled
, &delay_list
);
2191 if (!delay_list
.is_empty ())
2192 unfilled_slots_base
[i
]
2193 = emit_delay_sequence (insn
, delay_list
, slots_filled
);
2195 if (slots_to_fill
== slots_filled
)
2196 unfilled_slots_base
[i
] = 0;
2198 note_delay_statistics (slots_filled
, 0);
2202 /* Follow any unconditional jump at LABEL, for the purpose of redirecting JUMP;
2203 return the ultimate label reached by any such chain of jumps.
2204 Return a suitable return rtx if the chain ultimately leads to a
2206 If LABEL is not followed by a jump, return LABEL.
2207 If the chain loops or we can't find end, return LABEL,
2208 since that tells caller to avoid changing the insn.
2209 If the returned label is obtained by following a crossing jump,
2210 set *CROSSING to true, otherwise set it to false. */
2213 follow_jumps (rtx label
, rtx_insn
*jump
, bool *crossing
)
2220 if (ANY_RETURN_P (label
))
2223 rtx_insn
*value
= as_a
<rtx_insn
*> (label
);
2227 && (insn
= next_active_insn (value
)) != 0
2229 && JUMP_LABEL (insn
) != NULL_RTX
2230 && ((any_uncondjump_p (insn
) && onlyjump_p (insn
))
2231 || ANY_RETURN_P (PATTERN (insn
)))
2232 && (next
= NEXT_INSN (insn
))
2233 && BARRIER_P (next
));
2236 rtx this_label_or_return
= JUMP_LABEL (insn
);
2238 /* If we have found a cycle, make the insn jump to itself. */
2239 if (this_label_or_return
== label
)
2242 /* Cannot follow returns and cannot look through tablejumps. */
2243 if (ANY_RETURN_P (this_label_or_return
))
2244 return this_label_or_return
;
2246 rtx_insn
*this_label
= as_a
<rtx_insn
*> (this_label_or_return
);
2247 if (NEXT_INSN (this_label
)
2248 && JUMP_TABLE_DATA_P (NEXT_INSN (this_label
)))
2251 if (!targetm
.can_follow_jump (jump
, insn
))
2254 *crossing
= CROSSING_JUMP_P (jump
);
2262 /* Try to find insns to place in delay slots.
2264 INSN is the jump needing SLOTS_TO_FILL delay slots. It tests CONDITION
2265 or is an unconditional branch if CONDITION is const_true_rtx.
2266 *PSLOTS_FILLED is updated with the number of slots that we have filled.
2268 THREAD is a flow-of-control, either the insns to be executed if the
2269 branch is true or if the branch is false, THREAD_IF_TRUE says which.
2271 OPPOSITE_THREAD is the thread in the opposite direction. It is used
2272 to see if any potential delay slot insns set things needed there.
2274 LIKELY is true if it is extremely likely that the branch will be
2275 taken and THREAD_IF_TRUE is set. This is used for the branch at the
2276 end of a loop back up to the top.
2278 OWN_THREAD is true if we are the only user of the thread, i.e. it is
2279 the target of the jump when we are the only jump going there.
2281 If OWN_THREAD is false, it must be the "true" thread of a jump. In that
2282 case, we can only take insns from the head of the thread for our delay
2283 slot. We then adjust the jump to point after the insns we have taken. */
2286 fill_slots_from_thread (rtx_jump_insn
*insn
, rtx condition
,
2287 rtx thread_or_return
, rtx opposite_thread
, bool likely
,
2288 bool thread_if_true
, bool own_thread
, int slots_to_fill
,
2289 int *pslots_filled
, vec
<rtx_insn
*> *delay_list
)
2292 struct resources opposite_needed
, set
, needed
;
2295 bool must_annul
= false;
2298 /* Validate our arguments. */
2299 gcc_assert (condition
!= const_true_rtx
|| thread_if_true
);
2300 gcc_assert (own_thread
|| thread_if_true
);
2302 flags
= get_jump_flags (insn
, JUMP_LABEL (insn
));
2304 /* If our thread is the end of subroutine, we can't get any delay
2306 if (thread_or_return
== NULL_RTX
|| ANY_RETURN_P (thread_or_return
))
2309 rtx_insn
*thread
= as_a
<rtx_insn
*> (thread_or_return
);
2311 /* If this is an unconditional branch, nothing is needed at the
2312 opposite thread. Otherwise, compute what is needed there. */
2313 if (condition
== const_true_rtx
)
2314 CLEAR_RESOURCE (&opposite_needed
);
2316 mark_target_live_regs (get_insns (), opposite_thread
, &opposite_needed
);
2318 /* If the insn at THREAD can be split, do it here to avoid having to
2319 update THREAD and NEW_THREAD if it is done in the loop below. Also
2320 initialize NEW_THREAD. */
2322 new_thread
= thread
= try_split (PATTERN (thread
), thread
, 0);
2324 /* Scan insns at THREAD. We are looking for an insn that can be removed
2325 from THREAD (it neither sets nor references resources that were set
2326 ahead of it and it doesn't set anything needs by the insns ahead of
2327 it) and that either can be placed in an annulling insn or aren't
2328 needed at OPPOSITE_THREAD. */
2330 CLEAR_RESOURCE (&needed
);
2331 CLEAR_RESOURCE (&set
);
2333 /* Handle the flags register specially, to be able to accept a
2334 candidate that clobbers it. See also fill_simple_delay_slots. */
2336 = (slots_to_fill
== 1
2337 && targetm
.flags_regnum
!= INVALID_REGNUM
2338 && find_regno_note (insn
, REG_DEAD
, targetm
.flags_regnum
));
2339 struct resources fset
;
2340 struct resources flags_res
;
2343 CLEAR_RESOURCE (&fset
);
2344 CLEAR_RESOURCE (&flags_res
);
2345 SET_HARD_REG_BIT (flags_res
.regs
, targetm
.flags_regnum
);
2348 /* If we do not own this thread, we must stop as soon as we find
2349 something that we can't put in a delay slot, since all we can do
2350 is branch into THREAD at a later point. Therefore, labels stop
2351 the search if this is not the `true' thread. */
2353 for (trial
= thread
;
2354 ! stop_search_p (trial
, ! thread_if_true
) && (! lose
|| own_thread
);
2355 trial
= next_nonnote_insn (trial
))
2359 /* If we have passed a label, we no longer own this thread. */
2360 if (LABEL_P (trial
))
2366 pat
= PATTERN (trial
);
2367 if (GET_CODE (pat
) == USE
|| GET_CODE (pat
) == CLOBBER
)
2370 if (GET_CODE (trial
) == DEBUG_INSN
)
2373 /* If TRIAL conflicts with the insns ahead of it, we lose. */
2374 if (! insn_references_resource_p (trial
, &set
, true)
2375 && ! insn_sets_resource_p (trial
, filter_flags
? &fset
: &set
, true)
2376 && ! insn_sets_resource_p (trial
, &needed
, true)
2377 /* If we're handling sets to the flags register specially, we
2378 only allow an insn into a delay-slot, if it either:
2379 - doesn't set the flags register,
2380 - the "set" of the flags register isn't used (clobbered),
2381 - insns between the delay-slot insn and the trial-insn
2382 as accounted in "set", have not affected the flags register. */
2384 || ! insn_sets_resource_p (trial
, &flags_res
, true)
2385 || find_regno_note (trial
, REG_UNUSED
, targetm
.flags_regnum
)
2386 || ! TEST_HARD_REG_BIT (set
.regs
, targetm
.flags_regnum
))
2387 && ! can_throw_internal (trial
))
2389 rtx_insn
*prior_insn
;
2391 /* If TRIAL is redundant with some insn before INSN, we don't
2392 actually need to add it to the delay list; we can merely pretend
2394 if ((prior_insn
= redundant_insn (trial
, insn
, *delay_list
)))
2396 fix_reg_dead_note (prior_insn
, insn
);
2399 update_block (trial
, thread
);
2400 if (trial
== thread
)
2402 thread
= next_active_insn (thread
);
2403 if (new_thread
== trial
)
2404 new_thread
= thread
;
2407 delete_related_insns (trial
);
2411 update_reg_unused_notes (prior_insn
, trial
);
2412 new_thread
= next_active_insn (trial
);
2418 /* There are two ways we can win: If TRIAL doesn't set anything
2419 needed at the opposite thread and can't trap, or if it can
2420 go into an annulled delay slot. But we want neither to copy
2421 nor to speculate frame-related insns. */
2423 && ((condition
== const_true_rtx
2424 && (own_thread
|| !RTX_FRAME_RELATED_P (trial
)))
2425 || (! insn_sets_resource_p (trial
, &opposite_needed
, true)
2426 && ! may_trap_or_fault_p (pat
)
2427 && ! RTX_FRAME_RELATED_P (trial
))))
2430 trial
= try_split (pat
, trial
, 0);
2431 if (new_thread
== old_trial
)
2433 if (thread
== old_trial
)
2435 pat
= PATTERN (trial
);
2436 if (eligible_for_delay (insn
, *pslots_filled
, trial
, flags
))
2439 else if (!RTX_FRAME_RELATED_P (trial
)
2440 && ((ANNUL_IFTRUE_SLOTS
&& ! thread_if_true
)
2441 || (ANNUL_IFFALSE_SLOTS
&& thread_if_true
)))
2444 trial
= try_split (pat
, trial
, 0);
2445 if (new_thread
== old_trial
)
2447 if (thread
== old_trial
)
2449 pat
= PATTERN (trial
);
2450 if ((must_annul
|| delay_list
->is_empty ()) && (thread_if_true
2451 ? check_annul_list_true_false (false, *delay_list
)
2452 && eligible_for_annul_false (insn
, *pslots_filled
, trial
, flags
)
2453 : check_annul_list_true_false (true, *delay_list
)
2454 && eligible_for_annul_true (insn
, *pslots_filled
, trial
, flags
)))
2461 /* If we own this thread, delete the insn. If this is the
2462 destination of a branch, show that a basic block status
2463 may have been updated. In any case, mark the new
2464 starting point of this thread. */
2469 update_block (trial
, thread
);
2470 if (trial
== thread
)
2472 thread
= next_active_insn (thread
);
2473 if (new_thread
== trial
)
2474 new_thread
= thread
;
2477 /* We are moving this insn, not deleting it. We must
2478 temporarily increment the use count on any referenced
2479 label lest it be deleted by delete_related_insns. */
2480 for (note
= REG_NOTES (trial
);
2482 note
= XEXP (note
, 1))
2483 if (REG_NOTE_KIND (note
) == REG_LABEL_OPERAND
2484 || REG_NOTE_KIND (note
) == REG_LABEL_TARGET
)
2486 /* REG_LABEL_OPERAND could be
2487 NOTE_INSN_DELETED_LABEL too. */
2488 if (LABEL_P (XEXP (note
, 0)))
2489 LABEL_NUSES (XEXP (note
, 0))++;
2491 gcc_assert (REG_NOTE_KIND (note
)
2492 == REG_LABEL_OPERAND
);
2494 if (jump_to_label_p (trial
))
2495 LABEL_NUSES (JUMP_LABEL (trial
))++;
2497 delete_related_insns (trial
);
2499 for (note
= REG_NOTES (trial
);
2501 note
= XEXP (note
, 1))
2502 if (REG_NOTE_KIND (note
) == REG_LABEL_OPERAND
2503 || REG_NOTE_KIND (note
) == REG_LABEL_TARGET
)
2505 /* REG_LABEL_OPERAND could be
2506 NOTE_INSN_DELETED_LABEL too. */
2507 if (LABEL_P (XEXP (note
, 0)))
2508 LABEL_NUSES (XEXP (note
, 0))--;
2510 gcc_assert (REG_NOTE_KIND (note
)
2511 == REG_LABEL_OPERAND
);
2513 if (jump_to_label_p (trial
))
2514 LABEL_NUSES (JUMP_LABEL (trial
))--;
2517 new_thread
= next_active_insn (trial
);
2519 temp
= own_thread
? trial
: copy_delay_slot_insn (trial
);
2521 INSN_FROM_TARGET_P (temp
) = 1;
2523 add_to_delay_list (temp
, delay_list
);
2525 if (slots_to_fill
== ++(*pslots_filled
))
2527 /* Even though we have filled all the slots, we
2528 may be branching to a location that has a
2529 redundant insn. Skip any if so. */
2530 while (new_thread
&& ! own_thread
2531 && ! insn_sets_resource_p (new_thread
, &set
, true)
2532 && ! insn_sets_resource_p (new_thread
, &needed
,
2534 && ! insn_references_resource_p (new_thread
,
2537 = redundant_insn (new_thread
, insn
,
2540 /* We know we do not own the thread, so no need
2541 to call update_block and delete_insn. */
2542 fix_reg_dead_note (prior_insn
, insn
);
2543 update_reg_unused_notes (prior_insn
, new_thread
);
2545 = next_active_insn (as_a
<rtx_insn
*> (new_thread
));
2555 /* This insn can't go into a delay slot. */
2557 mark_set_resources (trial
, &set
, 0, MARK_SRC_DEST_CALL
);
2558 mark_referenced_resources (trial
, &needed
, true);
2561 mark_set_resources (trial
, &fset
, 0, MARK_SRC_DEST_CALL
);
2563 /* Groups of flags-register setters with users should not
2564 affect opportunities to move flags-register-setting insns
2565 (clobbers) into the delay-slot. */
2566 CLEAR_HARD_REG_BIT (needed
.regs
, targetm
.flags_regnum
);
2567 CLEAR_HARD_REG_BIT (fset
.regs
, targetm
.flags_regnum
);
2570 /* Ensure we don't put insns between the setting of cc and the comparison
2571 by moving a setting of cc into an earlier delay slot since these insns
2572 could clobber the condition code. */
2575 /* If this insn is a register-register copy and the next insn has
2576 a use of our destination, change it to use our source. That way,
2577 it will become a candidate for our delay slot the next time
2578 through this loop. This case occurs commonly in loops that
2581 We could check for more complex cases than those tested below,
2582 but it doesn't seem worth it. It might also be a good idea to try
2583 to swap the two insns. That might do better.
2585 We can't do this if the next insn modifies our destination, because
2586 that would make the replacement into the insn invalid. We also can't
2587 do this if it modifies our source, because it might be an earlyclobber
2588 operand. This latter test also prevents updating the contents of
2589 a PRE_INC. We also can't do this if there's overlap of source and
2590 destination. Overlap may happen for larger-than-register-size modes. */
2592 if (NONJUMP_INSN_P (trial
) && GET_CODE (pat
) == SET
2593 && REG_P (SET_SRC (pat
))
2594 && REG_P (SET_DEST (pat
))
2595 && !reg_overlap_mentioned_p (SET_DEST (pat
), SET_SRC (pat
)))
2597 rtx_insn
*next
= next_nonnote_insn (trial
);
2599 if (next
&& NONJUMP_INSN_P (next
)
2600 && GET_CODE (PATTERN (next
)) != USE
2601 && ! reg_set_p (SET_DEST (pat
), next
)
2602 && ! reg_set_p (SET_SRC (pat
), next
)
2603 && reg_referenced_p (SET_DEST (pat
), PATTERN (next
))
2604 && ! modified_in_p (SET_DEST (pat
), next
))
2605 validate_replace_rtx (SET_DEST (pat
), SET_SRC (pat
), next
);
2609 /* If we stopped on a branch insn that has delay slots, see if we can
2610 steal some of the insns in those slots. */
2611 if (trial
&& NONJUMP_INSN_P (trial
)
2612 && GET_CODE (PATTERN (trial
)) == SEQUENCE
2613 && JUMP_P (XVECEXP (PATTERN (trial
), 0, 0)))
2615 rtx_sequence
*sequence
= as_a
<rtx_sequence
*> (PATTERN (trial
));
2616 /* If this is the `true' thread, we will want to follow the jump,
2617 so we can only do this if we have taken everything up to here. */
2618 if (thread_if_true
&& trial
== new_thread
)
2620 steal_delay_list_from_target (insn
, condition
, sequence
,
2621 delay_list
, &set
, &needed
,
2622 &opposite_needed
, slots_to_fill
,
2623 pslots_filled
, &must_annul
,
2625 /* If we owned the thread and are told that it branched
2626 elsewhere, make sure we own the thread at the new location. */
2627 if (own_thread
&& trial
!= new_thread
)
2628 own_thread
= own_thread_p (new_thread
, new_thread
, false);
2630 else if (! thread_if_true
)
2631 steal_delay_list_from_fallthrough (insn
, condition
, sequence
,
2632 delay_list
, &set
, &needed
,
2633 &opposite_needed
, slots_to_fill
,
2634 pslots_filled
, &must_annul
);
2637 /* If we haven't found anything for this delay slot and it is very
2638 likely that the branch will be taken, see if the insn at our target
2639 increments or decrements a register with an increment that does not
2640 depend on the destination register. If so, try to place the opposite
2641 arithmetic insn after the jump insn and put the arithmetic insn in the
2642 delay slot. If we can't do this, return. */
2643 if (delay_list
->is_empty () && likely
2645 && !ANY_RETURN_P (new_thread
)
2646 && NONJUMP_INSN_P (new_thread
)
2647 && !RTX_FRAME_RELATED_P (new_thread
)
2648 && GET_CODE (PATTERN (new_thread
)) != ASM_INPUT
2649 && asm_noperands (PATTERN (new_thread
)) < 0)
2654 /* We know "new_thread" is an insn due to NONJUMP_INSN_P (new_thread)
2656 trial
= as_a
<rtx_insn
*> (new_thread
);
2657 rtx pat
= PATTERN (trial
);
2659 if (!NONJUMP_INSN_P (trial
)
2660 || GET_CODE (pat
) != SET
2661 || ! eligible_for_delay (insn
, 0, trial
, flags
)
2662 || can_throw_internal (trial
))
2665 dest
= SET_DEST (pat
), src
= SET_SRC (pat
);
2666 if ((GET_CODE (src
) == PLUS
|| GET_CODE (src
) == MINUS
)
2667 && rtx_equal_p (XEXP (src
, 0), dest
)
2668 && (!FLOAT_MODE_P (GET_MODE (src
))
2669 || flag_unsafe_math_optimizations
)
2670 && ! reg_overlap_mentioned_p (dest
, XEXP (src
, 1))
2671 && ! side_effects_p (pat
))
2673 rtx other
= XEXP (src
, 1);
2677 /* If this is a constant adjustment, use the same code with
2678 the negated constant. Otherwise, reverse the sense of the
2680 if (CONST_INT_P (other
))
2681 new_arith
= gen_rtx_fmt_ee (GET_CODE (src
), GET_MODE (src
), dest
,
2682 negate_rtx (GET_MODE (src
), other
));
2684 new_arith
= gen_rtx_fmt_ee (GET_CODE (src
) == PLUS
? MINUS
: PLUS
,
2685 GET_MODE (src
), dest
, other
);
2687 ninsn
= emit_insn_after (gen_rtx_SET (dest
, new_arith
), insn
);
2689 if (recog_memoized (ninsn
) < 0
2690 || (extract_insn (ninsn
),
2691 !constrain_operands (1, get_preferred_alternatives (ninsn
))))
2693 delete_related_insns (ninsn
);
2699 update_block (trial
, thread
);
2700 if (trial
== thread
)
2702 thread
= next_active_insn (thread
);
2703 if (new_thread
== trial
)
2704 new_thread
= thread
;
2706 delete_related_insns (trial
);
2709 new_thread
= next_active_insn (trial
);
2711 ninsn
= own_thread
? trial
: copy_delay_slot_insn (trial
);
2713 INSN_FROM_TARGET_P (ninsn
) = 1;
2715 add_to_delay_list (ninsn
, delay_list
);
2720 if (!delay_list
->is_empty () && must_annul
)
2721 INSN_ANNULLED_BRANCH_P (insn
) = 1;
2723 /* If we are to branch into the middle of this thread, find an appropriate
2724 label or make a new one if none, and redirect INSN to it. If we hit the
2725 end of the function, use the end-of-function label. */
2726 if (new_thread
!= thread
)
2729 bool crossing
= false;
2731 gcc_assert (thread_if_true
);
2734 && simplejump_or_return_p (new_thread
)
2735 && redirect_with_delay_list_safe_p (insn
,
2736 JUMP_LABEL (new_thread
),
2738 new_thread
= follow_jumps (JUMP_LABEL (new_thread
), insn
, &crossing
);
2741 label
= find_end_label (simple_return_rtx
);
2742 else if (ANY_RETURN_P (new_thread
))
2743 label
= find_end_label (new_thread
);
2744 else if (LABEL_P (new_thread
))
2747 label
= get_label_before (as_a
<rtx_insn
*> (new_thread
),
2752 reorg_redirect_jump (insn
, label
);
2754 CROSSING_JUMP_P (insn
) = 1;
2759 /* Make another attempt to find insns to place in delay slots.
2761 We previously looked for insns located in front of the delay insn
2762 and, for non-jump delay insns, located behind the delay insn.
2764 Here only try to schedule jump insns and try to move insns from either
2765 the target or the following insns into the delay slot. If annulling is
2766 supported, we will be likely to do this. Otherwise, we can do this only
2770 fill_eager_delay_slots (void)
2774 int num_unfilled_slots
= unfilled_slots_next
- unfilled_slots_base
;
2776 for (i
= 0; i
< num_unfilled_slots
; i
++)
2779 rtx target_label
, insn_at_target
;
2780 rtx_insn
*fallthrough_insn
;
2781 auto_vec
<rtx_insn
*, 5> delay_list
;
2782 rtx_jump_insn
*jump_insn
;
2784 bool own_fallthrough
;
2785 int prediction
, slots_to_fill
, slots_filled
;
2787 insn
= unfilled_slots_base
[i
];
2790 || ! (jump_insn
= dyn_cast
<rtx_jump_insn
*> (insn
))
2791 || ! (condjump_p (jump_insn
) || condjump_in_parallel_p (jump_insn
)))
2794 slots_to_fill
= num_delay_slots (jump_insn
);
2795 /* Some machine description have defined instructions to have
2796 delay slots only in certain circumstances which may depend on
2797 nearby insns (which change due to reorg's actions).
2799 For example, the PA port normally has delay slots for unconditional
2802 However, the PA port claims such jumps do not have a delay slot
2803 if they are immediate successors of certain CALL_INSNs. This
2804 allows the port to favor filling the delay slot of the call with
2805 the unconditional jump. */
2806 if (slots_to_fill
== 0)
2810 target_label
= JUMP_LABEL (jump_insn
);
2811 condition
= get_branch_condition (jump_insn
, target_label
);
2816 /* Get the next active fallthrough and target insns and see if we own
2817 them. Then see whether the branch is likely true. We don't need
2818 to do a lot of this for unconditional branches. */
2820 insn_at_target
= first_active_target_insn (target_label
);
2821 own_target
= own_thread_p (target_label
, target_label
, false);
2823 if (condition
== const_true_rtx
)
2825 own_fallthrough
= false;
2826 fallthrough_insn
= 0;
2831 fallthrough_insn
= next_active_insn (jump_insn
);
2832 own_fallthrough
= own_thread_p (NEXT_INSN (jump_insn
),
2834 prediction
= mostly_true_jump (jump_insn
);
2837 /* If this insn is expected to branch, first try to get insns from our
2838 target, then our fallthrough insns. If it is not expected to branch,
2839 try the other order. */
2843 fill_slots_from_thread (jump_insn
, condition
, insn_at_target
,
2844 fallthrough_insn
, prediction
== 2, true,
2845 own_target
, slots_to_fill
,
2846 &slots_filled
, &delay_list
);
2848 if (delay_list
.is_empty () && own_fallthrough
)
2850 /* Even though we didn't find anything for delay slots,
2851 we might have found a redundant insn which we deleted
2852 from the thread that was filled. So we have to recompute
2853 the next insn at the target. */
2854 target_label
= JUMP_LABEL (jump_insn
);
2855 insn_at_target
= first_active_target_insn (target_label
);
2857 fill_slots_from_thread (jump_insn
, condition
, fallthrough_insn
,
2858 insn_at_target
, false, false,
2859 own_fallthrough
, slots_to_fill
,
2860 &slots_filled
, &delay_list
);
2865 if (own_fallthrough
)
2866 fill_slots_from_thread (jump_insn
, condition
, fallthrough_insn
,
2867 insn_at_target
, false, false,
2868 own_fallthrough
, slots_to_fill
,
2869 &slots_filled
, &delay_list
);
2871 if (delay_list
.is_empty ())
2872 fill_slots_from_thread (jump_insn
, condition
, insn_at_target
,
2873 next_active_insn (insn
), false, true,
2874 own_target
, slots_to_fill
,
2875 &slots_filled
, &delay_list
);
2878 if (!delay_list
.is_empty ())
2879 unfilled_slots_base
[i
]
2880 = emit_delay_sequence (jump_insn
, delay_list
, slots_filled
);
2882 if (slots_to_fill
== slots_filled
)
2883 unfilled_slots_base
[i
] = 0;
2885 note_delay_statistics (slots_filled
, 1);
2889 static void delete_computation (rtx_insn
*insn
);
2891 /* Recursively delete prior insns that compute the value (used only by INSN
2892 which the caller is deleting) stored in the register mentioned by NOTE
2893 which is a REG_DEAD note associated with INSN. */
2896 delete_prior_computation (rtx note
, rtx_insn
*insn
)
2899 rtx reg
= XEXP (note
, 0);
2901 for (our_prev
= prev_nonnote_insn (insn
);
2902 our_prev
&& (NONJUMP_INSN_P (our_prev
)
2903 || CALL_P (our_prev
));
2904 our_prev
= prev_nonnote_insn (our_prev
))
2906 rtx pat
= PATTERN (our_prev
);
2908 /* If we reach a CALL which is not calling a const function
2909 or the callee pops the arguments, then give up. */
2910 if (CALL_P (our_prev
)
2911 && (! RTL_CONST_CALL_P (our_prev
)
2912 || GET_CODE (pat
) != SET
|| GET_CODE (SET_SRC (pat
)) != CALL
))
2915 /* If we reach a SEQUENCE, it is too complex to try to
2916 do anything with it, so give up. We can be run during
2917 and after reorg, so SEQUENCE rtl can legitimately show
2919 if (GET_CODE (pat
) == SEQUENCE
)
2922 if (GET_CODE (pat
) == USE
2923 && NONJUMP_INSN_P (XEXP (pat
, 0)))
2924 /* reorg creates USEs that look like this. We leave them
2925 alone because reorg needs them for its own purposes. */
2928 if (reg_set_p (reg
, pat
))
2930 if (side_effects_p (pat
) && !CALL_P (our_prev
))
2933 if (GET_CODE (pat
) == PARALLEL
)
2935 /* If we find a SET of something else, we can't
2940 for (i
= 0; i
< XVECLEN (pat
, 0); i
++)
2942 rtx part
= XVECEXP (pat
, 0, i
);
2944 if (GET_CODE (part
) == SET
2945 && SET_DEST (part
) != reg
)
2949 if (i
== XVECLEN (pat
, 0))
2950 delete_computation (our_prev
);
2952 else if (GET_CODE (pat
) == SET
2953 && REG_P (SET_DEST (pat
)))
2955 int dest_regno
= REGNO (SET_DEST (pat
));
2956 int dest_endregno
= END_REGNO (SET_DEST (pat
));
2957 int regno
= REGNO (reg
);
2958 int endregno
= END_REGNO (reg
);
2960 if (dest_regno
>= regno
2961 && dest_endregno
<= endregno
)
2962 delete_computation (our_prev
);
2964 /* We may have a multi-word hard register and some, but not
2965 all, of the words of the register are needed in subsequent
2966 insns. Write REG_UNUSED notes for those parts that were not
2968 else if (dest_regno
<= regno
2969 && dest_endregno
>= endregno
)
2973 add_reg_note (our_prev
, REG_UNUSED
, reg
);
2975 for (i
= dest_regno
; i
< dest_endregno
; i
++)
2976 if (! find_regno_note (our_prev
, REG_UNUSED
, i
))
2979 if (i
== dest_endregno
)
2980 delete_computation (our_prev
);
2987 /* If PAT references the register that dies here, it is an
2988 additional use. Hence any prior SET isn't dead. However, this
2989 insn becomes the new place for the REG_DEAD note. */
2990 if (reg_overlap_mentioned_p (reg
, pat
))
2992 XEXP (note
, 1) = REG_NOTES (our_prev
);
2993 REG_NOTES (our_prev
) = note
;
2999 /* Delete INSN and recursively delete insns that compute values used only
3000 by INSN. This uses the REG_DEAD notes computed during flow analysis.
3002 Look at all our REG_DEAD notes. If a previous insn does nothing other
3003 than set a register that dies in this insn, we can delete that insn
3007 delete_computation (rtx_insn
*insn
)
3011 for (note
= REG_NOTES (insn
); note
; note
= next
)
3013 next
= XEXP (note
, 1);
3015 if (REG_NOTE_KIND (note
) != REG_DEAD
3016 /* Verify that the REG_NOTE is legitimate. */
3017 || !REG_P (XEXP (note
, 0)))
3020 delete_prior_computation (note
, insn
);
3023 delete_related_insns (insn
);
3026 /* If all INSN does is set the pc, delete it,
3027 and delete the insn that set the condition codes for it
3028 if that's what the previous thing was. */
3031 delete_jump (rtx_insn
*insn
)
3033 rtx set
= single_set (insn
);
3035 if (set
&& GET_CODE (SET_DEST (set
)) == PC
)
3036 delete_computation (insn
);
3040 label_before_next_insn (rtx_insn
*x
, rtx scan_limit
)
3042 rtx_insn
*insn
= next_active_insn (x
);
3045 insn
= PREV_INSN (insn
);
3046 if (insn
== scan_limit
|| insn
== NULL_RTX
)
3054 /* Return TRUE if there is a NOTE_INSN_SWITCH_TEXT_SECTIONS note in between
3058 switch_text_sections_between_p (const rtx_insn
*beg
, const rtx_insn
*end
)
3061 for (p
= beg
; p
!= end
; p
= NEXT_INSN (p
))
3062 if (NOTE_P (p
) && NOTE_KIND (p
) == NOTE_INSN_SWITCH_TEXT_SECTIONS
)
3068 /* Once we have tried two ways to fill a delay slot, make a pass over the
3069 code to try to improve the results and to do such things as more jump
3073 relax_delay_slots (rtx_insn
*first
)
3075 rtx_insn
*insn
, *next
;
3077 rtx_insn
*delay_insn
;
3080 /* Look at every JUMP_INSN and see if we can improve it. */
3081 for (insn
= first
; insn
; insn
= next
)
3083 rtx_insn
*other
, *prior_insn
;
3086 next
= next_active_insn (insn
);
3088 /* If this is a jump insn, see if it now jumps to a jump, jumps to
3089 the next insn, or jumps to a label that is not the last of a
3090 group of consecutive labels. */
3091 if (is_a
<rtx_jump_insn
*> (insn
)
3092 && (condjump_p (insn
) || condjump_in_parallel_p (insn
))
3093 && !ANY_RETURN_P (target_label
= JUMP_LABEL (insn
)))
3095 rtx_jump_insn
*jump_insn
= as_a
<rtx_jump_insn
*> (insn
);
3097 = skip_consecutive_labels (follow_jumps (target_label
, jump_insn
,
3099 if (ANY_RETURN_P (target_label
))
3100 target_label
= find_end_label (target_label
);
3103 && next_active_insn (as_a
<rtx_insn
*> (target_label
)) == next
3104 && ! condjump_in_parallel_p (jump_insn
)
3105 && ! (next
&& switch_text_sections_between_p (jump_insn
, next
)))
3107 rtx_insn
*direct_label
= as_a
<rtx_insn
*> (JUMP_LABEL (insn
));
3108 rtx_insn
*prev
= prev_nonnote_insn (direct_label
);
3110 /* If the insn jumps over a BARRIER and is the only way to reach
3111 its target, then we need to delete the BARRIER before the jump
3112 because, otherwise, the target may end up being considered as
3113 unreachable and thus also deleted. */
3114 if (BARRIER_P (prev
) && LABEL_NUSES (direct_label
) == 1)
3116 delete_related_insns (prev
);
3118 /* We have just removed a BARRIER, which means that the block
3119 number of the next insns has effectively been changed (see
3120 find_basic_block in resource.cc), so clear it. */
3121 clear_hashed_info_until_next_barrier (direct_label
);
3124 delete_jump (jump_insn
);
3128 if (target_label
&& target_label
!= JUMP_LABEL (jump_insn
))
3130 reorg_redirect_jump (jump_insn
, target_label
);
3132 CROSSING_JUMP_P (jump_insn
) = 1;
3135 /* See if this jump conditionally branches around an unconditional
3136 jump. If so, invert this jump and point it to the target of the
3137 second jump. Check if it's possible on the target. */
3138 if (next
&& simplejump_or_return_p (next
)
3139 && any_condjump_p (jump_insn
)
3141 && (next_active_insn (as_a
<rtx_insn
*> (target_label
))
3142 == next_active_insn (next
))
3143 && no_labels_between_p (jump_insn
, next
)
3144 && targetm
.can_follow_jump (jump_insn
, next
))
3146 rtx label
= JUMP_LABEL (next
);
3148 /* Be careful how we do this to avoid deleting code or
3149 labels that are momentarily dead. See similar optimization
3152 We also need to ensure we properly handle the case when
3153 invert_jump fails. */
3155 ++LABEL_NUSES (target_label
);
3156 if (!ANY_RETURN_P (label
))
3157 ++LABEL_NUSES (label
);
3159 if (invert_jump (jump_insn
, label
, 1))
3161 rtx_insn
*from
= delete_related_insns (next
);
3163 /* We have just removed a BARRIER, which means that the block
3164 number of the next insns has effectively been changed (see
3165 find_basic_block in resource.cc), so clear it. */
3167 clear_hashed_info_until_next_barrier (from
);
3172 if (!ANY_RETURN_P (label
))
3173 --LABEL_NUSES (label
);
3175 if (--LABEL_NUSES (target_label
) == 0)
3176 delete_related_insns (target_label
);
3182 /* If this is an unconditional jump and the previous insn is a
3183 conditional jump, try reversing the condition of the previous
3184 insn and swapping our targets. The next pass might be able to
3187 Don't do this if we expect the conditional branch to be true, because
3188 we would then be making the more common case longer. */
3190 if (simplejump_or_return_p (insn
)
3191 && (other
= prev_active_insn (insn
)) != 0
3192 && any_condjump_p (other
)
3193 && no_labels_between_p (other
, insn
)
3194 && mostly_true_jump (other
) < 0)
3196 rtx other_target
= JUMP_LABEL (other
);
3197 target_label
= JUMP_LABEL (insn
);
3199 if (invert_jump (as_a
<rtx_jump_insn
*> (other
), target_label
, 0))
3200 reorg_redirect_jump (as_a
<rtx_jump_insn
*> (insn
), other_target
);
3203 /* Now look only at cases where we have a filled delay slot. */
3204 if (!NONJUMP_INSN_P (insn
) || GET_CODE (PATTERN (insn
)) != SEQUENCE
)
3207 pat
= as_a
<rtx_sequence
*> (PATTERN (insn
));
3208 delay_insn
= pat
->insn (0);
3210 /* See if the first insn in the delay slot is redundant with some
3211 previous insn. Remove it from the delay slot if so; then set up
3212 to reprocess this insn. */
3213 if ((prior_insn
= redundant_insn (pat
->insn (1), delay_insn
, vNULL
)))
3215 fix_reg_dead_note (prior_insn
, insn
);
3216 update_block (pat
->insn (1), insn
);
3217 delete_from_delay_slot (pat
->insn (1));
3218 next
= prev_active_insn (next
);
3222 /* See if we have a RETURN insn with a filled delay slot followed
3223 by a RETURN insn with an unfilled a delay slot. If so, we can delete
3224 the first RETURN (but not its delay insn). This gives the same
3225 effect in fewer instructions.
3227 Only do so if optimizing for size since this results in slower, but
3229 if (optimize_function_for_size_p (cfun
)
3230 && ANY_RETURN_P (PATTERN (delay_insn
))
3233 && PATTERN (next
) == PATTERN (delay_insn
))
3238 /* Delete the RETURN and just execute the delay list insns.
3240 We do this by deleting the INSN containing the SEQUENCE, then
3241 re-emitting the insns separately, and then deleting the RETURN.
3242 This allows the count of the jump target to be properly
3245 Note that we need to change the INSN_UID of the re-emitted insns
3246 since it is used to hash the insns for mark_target_live_regs and
3247 the re-emitted insns will no longer be wrapped up in a SEQUENCE.
3249 Clear the from target bit, since these insns are no longer
3251 for (i
= 0; i
< XVECLEN (pat
, 0); i
++)
3252 INSN_FROM_TARGET_P (XVECEXP (pat
, 0, i
)) = 0;
3254 rtx_insn
*prev
= PREV_INSN (insn
);
3255 delete_related_insns (insn
);
3256 gcc_assert (GET_CODE (pat
) == SEQUENCE
);
3257 add_insn_after (delay_insn
, prev
, NULL
);
3259 for (i
= 1; i
< pat
->len (); i
++)
3260 after
= emit_copy_of_insn_after (pat
->insn (i
), after
);
3261 delete_scheduled_jump (delay_insn
);
3265 /* Now look only at the cases where we have a filled JUMP_INSN. */
3266 rtx_jump_insn
*delay_jump_insn
=
3267 dyn_cast
<rtx_jump_insn
*> (delay_insn
);
3268 if (! delay_jump_insn
|| !(condjump_p (delay_jump_insn
)
3269 || condjump_in_parallel_p (delay_jump_insn
)))
3272 target_label
= JUMP_LABEL (delay_jump_insn
);
3273 if (target_label
&& ANY_RETURN_P (target_label
))
3276 /* If this jump goes to another unconditional jump, thread it, but
3277 don't convert a jump into a RETURN here. */
3278 rtx trial
= skip_consecutive_labels (follow_jumps (target_label
,
3281 if (ANY_RETURN_P (trial
))
3282 trial
= find_end_label (trial
);
3284 if (trial
&& trial
!= target_label
3285 && redirect_with_delay_slots_safe_p (delay_jump_insn
, trial
, insn
))
3287 reorg_redirect_jump (delay_jump_insn
, trial
);
3288 target_label
= trial
;
3290 CROSSING_JUMP_P (delay_jump_insn
) = 1;
3293 /* If the first insn at TARGET_LABEL is redundant with a previous
3294 insn, redirect the jump to the following insn and process again.
3295 We use next_real_nondebug_insn instead of next_active_insn so we
3296 don't skip USE-markers, or we'll end up with incorrect
3298 trial
= next_real_nondebug_insn (target_label
);
3299 if (trial
&& GET_CODE (PATTERN (trial
)) != SEQUENCE
3300 && redundant_insn (trial
, insn
, vNULL
)
3301 && ! can_throw_internal (trial
))
3303 /* Figure out where to emit the special USE insn so we don't
3304 later incorrectly compute register live/death info. */
3305 rtx_insn
*tmp
= next_active_insn (as_a
<rtx_insn
*> (trial
));
3307 tmp
= find_end_label (simple_return_rtx
);
3311 /* Insert the special USE insn and update dataflow info.
3312 We know "trial" is an insn here as it is the output of
3313 next_real_nondebug_insn () above. */
3314 update_block (as_a
<rtx_insn
*> (trial
), tmp
);
3316 /* Now emit a label before the special USE insn, and
3317 redirect our jump to the new label. */
3318 target_label
= get_label_before (PREV_INSN (tmp
), target_label
);
3319 reorg_redirect_jump (delay_jump_insn
, target_label
);
3325 /* Similarly, if it is an unconditional jump with one insn in its
3326 delay list and that insn is redundant, thread the jump. */
3327 rtx_sequence
*trial_seq
=
3328 trial
? dyn_cast
<rtx_sequence
*> (PATTERN (trial
)) : NULL
;
3330 && trial_seq
->len () == 2
3331 && JUMP_P (trial_seq
->insn (0))
3332 && simplejump_or_return_p (trial_seq
->insn (0))
3333 && redundant_insn (trial_seq
->insn (1), insn
, vNULL
))
3335 rtx temp_label
= JUMP_LABEL (trial_seq
->insn (0));
3336 if (ANY_RETURN_P (temp_label
))
3337 temp_label
= find_end_label (temp_label
);
3340 && redirect_with_delay_slots_safe_p (delay_jump_insn
,
3343 update_block (trial_seq
->insn (1), insn
);
3344 reorg_redirect_jump (delay_jump_insn
, temp_label
);
3350 /* See if we have a simple (conditional) jump that is useless. */
3351 if (!CROSSING_JUMP_P (delay_jump_insn
)
3352 && !INSN_ANNULLED_BRANCH_P (delay_jump_insn
)
3353 && !condjump_in_parallel_p (delay_jump_insn
)
3354 && prev_active_insn (as_a
<rtx_insn
*> (target_label
)) == insn
3355 && !BARRIER_P (prev_nonnote_insn (as_a
<rtx_insn
*> (target_label
))))
3360 /* All this insn does is execute its delay list and jump to the
3361 following insn. So delete the jump and just execute the delay
3364 We do this by deleting the INSN containing the SEQUENCE, then
3365 re-emitting the insns separately, and then deleting the jump.
3366 This allows the count of the jump target to be properly
3369 Note that we need to change the INSN_UID of the re-emitted insns
3370 since it is used to hash the insns for mark_target_live_regs and
3371 the re-emitted insns will no longer be wrapped up in a SEQUENCE.
3373 Clear the from target bit, since these insns are no longer
3375 for (i
= 0; i
< XVECLEN (pat
, 0); i
++)
3376 INSN_FROM_TARGET_P (XVECEXP (pat
, 0, i
)) = 0;
3378 rtx_insn
*prev
= PREV_INSN (insn
);
3379 delete_related_insns (insn
);
3380 gcc_assert (GET_CODE (pat
) == SEQUENCE
);
3381 add_insn_after (delay_jump_insn
, prev
, NULL
);
3382 after
= delay_jump_insn
;
3383 for (i
= 1; i
< pat
->len (); i
++)
3384 after
= emit_copy_of_insn_after (pat
->insn (i
), after
);
3385 delete_scheduled_jump (delay_jump_insn
);
3389 /* See if this is an unconditional jump around a single insn which is
3390 identical to the one in its delay slot. In this case, we can just
3391 delete the branch and the insn in its delay slot. */
3392 if (next
&& NONJUMP_INSN_P (next
)
3393 && label_before_next_insn (next
, insn
) == target_label
3394 && simplejump_p (insn
)
3395 && XVECLEN (pat
, 0) == 2
3396 && rtx_equal_p (PATTERN (next
), PATTERN (pat
->insn (1))))
3398 delete_related_insns (insn
);
3402 /* See if this jump (with its delay slots) conditionally branches
3403 around an unconditional jump (without delay slots). If so, invert
3404 this jump and point it to the target of the second jump. We cannot
3405 do this for annulled jumps, though. Again, don't convert a jump to
3407 if (! INSN_ANNULLED_BRANCH_P (delay_jump_insn
)
3408 && any_condjump_p (delay_jump_insn
)
3409 && next
&& simplejump_or_return_p (next
)
3410 && (next_active_insn (as_a
<rtx_insn
*> (target_label
))
3411 == next_active_insn (next
))
3412 && no_labels_between_p (insn
, next
))
3414 rtx label
= JUMP_LABEL (next
);
3415 rtx old_label
= JUMP_LABEL (delay_jump_insn
);
3417 if (ANY_RETURN_P (label
))
3418 label
= find_end_label (label
);
3420 /* find_end_label can generate a new label. Check this first. */
3422 && no_labels_between_p (insn
, next
)
3423 && redirect_with_delay_slots_safe_p (delay_jump_insn
,
3426 /* Be careful how we do this to avoid deleting code or labels
3427 that are momentarily dead. See similar optimization in
3430 ++LABEL_NUSES (old_label
);
3432 if (invert_jump (delay_jump_insn
, label
, 1))
3434 /* Must update the INSN_FROM_TARGET_P bits now that
3435 the branch is reversed, so that mark_target_live_regs
3436 will handle the delay slot insn correctly. */
3437 for (int i
= 1; i
< XVECLEN (PATTERN (insn
), 0); i
++)
3439 rtx slot
= XVECEXP (PATTERN (insn
), 0, i
);
3440 INSN_FROM_TARGET_P (slot
) = ! INSN_FROM_TARGET_P (slot
);
3443 /* We have just removed a BARRIER, which means that the block
3444 number of the next insns has effectively been changed (see
3445 find_basic_block in resource.cc), so clear it. */
3446 rtx_insn
*from
= delete_related_insns (next
);
3448 clear_hashed_info_until_next_barrier (from
);
3453 if (old_label
&& --LABEL_NUSES (old_label
) == 0)
3454 delete_related_insns (old_label
);
3459 /* If we own the thread opposite the way this insn branches, see if we
3460 can merge its delay slots with following insns. */
3461 if (INSN_FROM_TARGET_P (pat
->insn (1))
3462 && own_thread_p (NEXT_INSN (insn
), 0, true))
3463 try_merge_delay_insns (insn
, next
);
3464 else if (! INSN_FROM_TARGET_P (pat
->insn (1))
3465 && own_thread_p (target_label
, target_label
, false))
3466 try_merge_delay_insns (insn
,
3467 next_active_insn (as_a
<rtx_insn
*> (target_label
)));
3469 /* If we get here, we haven't deleted INSN. But we may have deleted
3470 NEXT, so recompute it. */
3471 next
= next_active_insn (insn
);
3476 /* Look for filled jumps to the end of function label. We can try to convert
3477 them into RETURN insns if the insns in the delay slot are valid for the
3481 make_return_insns (rtx_insn
*first
)
3484 rtx_jump_insn
*jump_insn
;
3485 rtx real_return_label
= function_return_label
;
3486 rtx real_simple_return_label
= function_simple_return_label
;
3489 /* See if there is a RETURN insn in the function other than the one we
3490 made for END_OF_FUNCTION_LABEL. If so, set up anything we can't change
3491 into a RETURN to jump to it. */
3492 for (insn
= first
; insn
; insn
= NEXT_INSN (insn
))
3493 if (JUMP_P (insn
) && ANY_RETURN_P (PATTERN (insn
)))
3495 rtx t
= get_label_before (insn
, NULL_RTX
);
3496 if (PATTERN (insn
) == ret_rtx
)
3497 real_return_label
= t
;
3499 real_simple_return_label
= t
;
3503 /* Show an extra usage of REAL_RETURN_LABEL so it won't go away if it
3504 was equal to END_OF_FUNCTION_LABEL. */
3505 if (real_return_label
)
3506 LABEL_NUSES (real_return_label
)++;
3507 if (real_simple_return_label
)
3508 LABEL_NUSES (real_simple_return_label
)++;
3510 /* Clear the list of insns to fill so we can use it. */
3511 obstack_free (&unfilled_slots_obstack
, unfilled_firstobj
);
3513 for (insn
= first
; insn
; insn
= NEXT_INSN (insn
))
3516 rtx kind
, real_label
;
3518 /* Only look at filled JUMP_INSNs that go to the end of function
3520 if (!NONJUMP_INSN_P (insn
))
3523 if (GET_CODE (PATTERN (insn
)) != SEQUENCE
)
3526 rtx_sequence
*pat
= as_a
<rtx_sequence
*> (PATTERN (insn
));
3528 if (!jump_to_label_p (pat
->insn (0)))
3531 if (JUMP_LABEL (pat
->insn (0)) == function_return_label
)
3534 real_label
= real_return_label
;
3536 else if (JUMP_LABEL (pat
->insn (0)) == function_simple_return_label
)
3538 kind
= simple_return_rtx
;
3539 real_label
= real_simple_return_label
;
3544 jump_insn
= as_a
<rtx_jump_insn
*> (pat
->insn (0));
3546 /* If we can't make the jump into a RETURN, try to redirect it to the best
3547 RETURN and go on to the next insn. */
3548 if (!reorg_redirect_jump (jump_insn
, kind
))
3550 /* Make sure redirecting the jump will not invalidate the delay
3552 if (redirect_with_delay_slots_safe_p (jump_insn
, real_label
, insn
))
3553 reorg_redirect_jump (jump_insn
, real_label
);
3557 /* See if this RETURN can accept the insns current in its delay slot.
3558 It can if it has more or an equal number of slots and the contents
3559 of each is valid. */
3561 flags
= get_jump_flags (jump_insn
, JUMP_LABEL (jump_insn
));
3562 slots
= num_delay_slots (jump_insn
);
3563 if (slots
>= XVECLEN (pat
, 0) - 1)
3565 for (i
= 1; i
< XVECLEN (pat
, 0); i
++)
3567 #if ANNUL_IFFALSE_SLOTS
3568 (INSN_ANNULLED_BRANCH_P (jump_insn
)
3569 && INSN_FROM_TARGET_P (pat
->insn (i
)))
3570 ? eligible_for_annul_false (jump_insn
, i
- 1,
3571 pat
->insn (i
), flags
) :
3573 #if ANNUL_IFTRUE_SLOTS
3574 (INSN_ANNULLED_BRANCH_P (jump_insn
)
3575 && ! INSN_FROM_TARGET_P (pat
->insn (i
)))
3576 ? eligible_for_annul_true (jump_insn
, i
- 1,
3577 pat
->insn (i
), flags
) :
3579 eligible_for_delay (jump_insn
, i
- 1,
3580 pat
->insn (i
), flags
)))
3586 if (i
== XVECLEN (pat
, 0))
3589 /* We have to do something with this insn. If it is an unconditional
3590 RETURN, delete the SEQUENCE and output the individual insns,
3591 followed by the RETURN. Then set things up so we try to find
3592 insns for its delay slots, if it needs some. */
3593 if (ANY_RETURN_P (PATTERN (jump_insn
)))
3595 rtx_insn
*after
= PREV_INSN (insn
);
3597 delete_related_insns (insn
);
3599 for (i
= 1; i
< pat
->len (); i
++)
3600 after
= emit_copy_of_insn_after (pat
->insn (i
), after
);
3601 add_insn_after (insn
, after
, NULL
);
3602 emit_barrier_after (insn
);
3605 obstack_ptr_grow (&unfilled_slots_obstack
, insn
);
3608 /* It is probably more efficient to keep this with its current
3609 delay slot as a branch to a RETURN. */
3610 reorg_redirect_jump (jump_insn
, real_label
);
3613 /* Now delete REAL_RETURN_LABEL if we never used it. Then try to fill any
3614 new delay slots we have created. */
3615 if (real_return_label
!= NULL_RTX
&& --LABEL_NUSES (real_return_label
) == 0)
3616 delete_related_insns (real_return_label
);
3617 if (real_simple_return_label
!= NULL_RTX
3618 && --LABEL_NUSES (real_simple_return_label
) == 0)
3619 delete_related_insns (real_simple_return_label
);
3621 fill_simple_delay_slots (true);
3622 fill_simple_delay_slots (false);
3625 /* Try to find insns to place in delay slots. */
3628 dbr_schedule (rtx_insn
*first
)
3630 rtx_insn
*insn
, *next
, *epilogue_insn
= 0;
3631 bool need_return_insns
;
3634 /* If the current function has no insns other than the prologue and
3635 epilogue, then do not try to fill any delay slots. */
3636 if (n_basic_blocks_for_fn (cfun
) == NUM_FIXED_BLOCKS
)
3639 /* Find the highest INSN_UID and allocate and initialize our map from
3640 INSN_UID's to position in code. */
3641 for (max_uid
= 0, insn
= first
; insn
; insn
= NEXT_INSN (insn
))
3643 if (INSN_UID (insn
) > max_uid
)
3644 max_uid
= INSN_UID (insn
);
3646 && NOTE_KIND (insn
) == NOTE_INSN_EPILOGUE_BEG
)
3647 epilogue_insn
= insn
;
3650 uid_to_ruid
= XNEWVEC (int, max_uid
+ 1);
3651 for (i
= 0, insn
= first
; insn
; i
++, insn
= NEXT_INSN (insn
))
3652 uid_to_ruid
[INSN_UID (insn
)] = i
;
3654 /* Initialize the list of insns that need filling. */
3655 if (unfilled_firstobj
== 0)
3657 gcc_obstack_init (&unfilled_slots_obstack
);
3658 unfilled_firstobj
= XOBNEWVAR (&unfilled_slots_obstack
, rtx
, 0);
3661 for (insn
= next_active_insn (first
); insn
; insn
= next_active_insn (insn
))
3665 /* Skip vector tables. We can't get attributes for them. */
3666 if (JUMP_TABLE_DATA_P (insn
))
3670 INSN_ANNULLED_BRANCH_P (insn
) = 0;
3671 INSN_FROM_TARGET_P (insn
) = 0;
3673 if (num_delay_slots (insn
) > 0)
3674 obstack_ptr_grow (&unfilled_slots_obstack
, insn
);
3676 /* Ensure all jumps go to the last of a set of consecutive labels. */
3678 && (condjump_p (insn
) || condjump_in_parallel_p (insn
))
3679 && !ANY_RETURN_P (JUMP_LABEL (insn
))
3680 && ((target
= skip_consecutive_labels (JUMP_LABEL (insn
)))
3681 != JUMP_LABEL (insn
)))
3682 redirect_jump (as_a
<rtx_jump_insn
*> (insn
), target
, 1);
3685 init_resource_info (epilogue_insn
);
3687 /* Show we haven't computed an end-of-function label yet. */
3688 function_return_label
= function_simple_return_label
= NULL
;
3690 /* Initialize the statistics for this function. */
3691 memset (num_insns_needing_delays
, 0, sizeof num_insns_needing_delays
);
3692 memset (num_filled_delays
, 0, sizeof num_filled_delays
);
3694 /* Now do the delay slot filling. Try everything twice in case earlier
3695 changes make more slots fillable. */
3697 for (reorg_pass_number
= 0;
3698 reorg_pass_number
< MAX_REORG_PASSES
;
3699 reorg_pass_number
++)
3701 fill_simple_delay_slots (true);
3702 fill_simple_delay_slots (false);
3703 if (!targetm
.no_speculation_in_delay_slots_p ())
3704 fill_eager_delay_slots ();
3705 relax_delay_slots (first
);
3708 /* If we made an end of function label, indicate that it is now
3709 safe to delete it by undoing our prior adjustment to LABEL_NUSES.
3710 If it is now unused, delete it. */
3711 if (function_return_label
&& --LABEL_NUSES (function_return_label
) == 0)
3712 delete_related_insns (function_return_label
);
3713 if (function_simple_return_label
3714 && --LABEL_NUSES (function_simple_return_label
) == 0)
3715 delete_related_insns (function_simple_return_label
);
3717 need_return_insns
= false;
3718 need_return_insns
|= targetm
.have_return () && function_return_label
!= 0;
3719 need_return_insns
|= (targetm
.have_simple_return ()
3720 && function_simple_return_label
!= 0);
3721 if (need_return_insns
)
3722 make_return_insns (first
);
3724 /* Delete any USE insns made by update_block; subsequent passes don't need
3725 them or know how to deal with them. */
3726 for (insn
= first
; insn
; insn
= next
)
3728 next
= NEXT_INSN (insn
);
3730 if (NONJUMP_INSN_P (insn
) && GET_CODE (PATTERN (insn
)) == USE
3731 && INSN_P (XEXP (PATTERN (insn
), 0)))
3732 next
= delete_related_insns (insn
);
3735 obstack_free (&unfilled_slots_obstack
, unfilled_firstobj
);
3737 /* It is not clear why the line below is needed, but it does seem to be. */
3738 unfilled_firstobj
= XOBNEWVAR (&unfilled_slots_obstack
, rtx
, 0);
3742 int i
, j
, need_comma
;
3743 int total_delay_slots
[MAX_DELAY_HISTOGRAM
+ 1];
3744 int total_annul_slots
[MAX_DELAY_HISTOGRAM
+ 1];
3746 for (reorg_pass_number
= 0;
3747 reorg_pass_number
< MAX_REORG_PASSES
;
3748 reorg_pass_number
++)
3750 fprintf (dump_file
, ";; Reorg pass #%d:\n", reorg_pass_number
+ 1);
3751 for (i
= 0; i
< NUM_REORG_FUNCTIONS
; i
++)
3754 fprintf (dump_file
, ";; Reorg function #%d\n", i
);
3756 fprintf (dump_file
, ";; %d insns needing delay slots\n;; ",
3757 num_insns_needing_delays
[i
][reorg_pass_number
]);
3759 for (j
= 0; j
< MAX_DELAY_HISTOGRAM
+ 1; j
++)
3760 if (num_filled_delays
[i
][j
][reorg_pass_number
])
3763 fprintf (dump_file
, ", ");
3765 fprintf (dump_file
, "%d got %d delays",
3766 num_filled_delays
[i
][j
][reorg_pass_number
], j
);
3768 fprintf (dump_file
, "\n");
3771 memset (total_delay_slots
, 0, sizeof total_delay_slots
);
3772 memset (total_annul_slots
, 0, sizeof total_annul_slots
);
3773 for (insn
= first
; insn
; insn
= NEXT_INSN (insn
))
3775 if (! insn
->deleted ()
3776 && NONJUMP_INSN_P (insn
)
3777 && GET_CODE (PATTERN (insn
)) != USE
3778 && GET_CODE (PATTERN (insn
)) != CLOBBER
)
3780 if (GET_CODE (PATTERN (insn
)) == SEQUENCE
)
3783 j
= XVECLEN (PATTERN (insn
), 0) - 1;
3784 if (j
> MAX_DELAY_HISTOGRAM
)
3785 j
= MAX_DELAY_HISTOGRAM
;
3786 control
= XVECEXP (PATTERN (insn
), 0, 0);
3787 if (JUMP_P (control
) && INSN_ANNULLED_BRANCH_P (control
))
3788 total_annul_slots
[j
]++;
3790 total_delay_slots
[j
]++;
3792 else if (num_delay_slots (insn
) > 0)
3793 total_delay_slots
[0]++;
3796 fprintf (dump_file
, ";; Reorg totals: ");
3798 for (j
= 0; j
< MAX_DELAY_HISTOGRAM
+ 1; j
++)
3800 if (total_delay_slots
[j
])
3803 fprintf (dump_file
, ", ");
3805 fprintf (dump_file
, "%d got %d delays", total_delay_slots
[j
], j
);
3808 fprintf (dump_file
, "\n");
3810 if (ANNUL_IFTRUE_SLOTS
|| ANNUL_IFFALSE_SLOTS
)
3812 fprintf (dump_file
, ";; Reorg annuls: ");
3814 for (j
= 0; j
< MAX_DELAY_HISTOGRAM
+ 1; j
++)
3816 if (total_annul_slots
[j
])
3819 fprintf (dump_file
, ", ");
3821 fprintf (dump_file
, "%d got %d delays", total_annul_slots
[j
], j
);
3824 fprintf (dump_file
, "\n");
3827 fprintf (dump_file
, "\n");
3830 if (!sibling_labels
.is_empty ())
3832 update_alignments (sibling_labels
);
3833 sibling_labels
.release ();
3836 free_resource_info ();
3838 crtl
->dbr_scheduled_p
= true;
3841 /* Run delay slot optimization. */
3843 rest_of_handle_delay_slots (void)
3846 dbr_schedule (get_insns ());
3851 const pass_data pass_data_delay_slots
=
3853 RTL_PASS
, /* type */
3855 OPTGROUP_NONE
, /* optinfo_flags */
3856 TV_DBR_SCHED
, /* tv_id */
3857 0, /* properties_required */
3858 0, /* properties_provided */
3859 0, /* properties_destroyed */
3860 0, /* todo_flags_start */
3861 0, /* todo_flags_finish */
3864 class pass_delay_slots
: public rtl_opt_pass
3867 pass_delay_slots (gcc::context
*ctxt
)
3868 : rtl_opt_pass (pass_data_delay_slots
, ctxt
)
3871 /* opt_pass methods: */
3872 bool gate (function
*) final override
;
3873 unsigned int execute (function
*) final override
3875 rest_of_handle_delay_slots ();
3879 }; // class pass_delay_slots
3882 pass_delay_slots::gate (function
*)
3884 /* At -O0 dataflow info isn't updated after RA. */
3886 return optimize
> 0 && flag_delayed_branch
&& !crtl
->dbr_scheduled_p
;
3894 make_pass_delay_slots (gcc::context
*ctxt
)
3896 return new pass_delay_slots (ctxt
);
3899 /* Machine dependent reorg pass. */
3903 const pass_data pass_data_machine_reorg
=
3905 RTL_PASS
, /* type */
3907 OPTGROUP_NONE
, /* optinfo_flags */
3908 TV_MACH_DEP
, /* tv_id */
3909 0, /* properties_required */
3910 0, /* properties_provided */
3911 0, /* properties_destroyed */
3912 0, /* todo_flags_start */
3913 0, /* todo_flags_finish */
3916 class pass_machine_reorg
: public rtl_opt_pass
3919 pass_machine_reorg (gcc::context
*ctxt
)
3920 : rtl_opt_pass (pass_data_machine_reorg
, ctxt
)
3923 /* opt_pass methods: */
3924 bool gate (function
*) final override
3926 return targetm
.machine_dependent_reorg
!= 0;
3929 unsigned int execute (function
*) final override
3931 targetm
.machine_dependent_reorg ();
3935 }; // class pass_machine_reorg
3940 make_pass_machine_reorg (gcc::context
*ctxt
)
3942 return new pass_machine_reorg (ctxt
);