1 /* Perform instruction reorganizations for delay slot filling.
2 Copyright (C) 1992-2014 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
93 On machines that use CC0, we are very conservative. We will not make
94 a copy of an insn involving CC0 since we want to maintain a 1-1
95 correspondence between the insn that sets and uses CC0. The insns are
96 allowed to be separated by placing an insn that sets CC0 (but not an insn
97 that uses CC0; we could do this, but it doesn't seem worthwhile) in a
98 delay slot. In that case, we point each insn at the other with REG_CC_USER
99 and REG_CC_SETTER notes. Note that these restrictions affect very few
100 machines because most RISC machines with delay slots will not use CC0
101 (the RT is the only known exception at this point). */
105 #include "coretypes.h"
107 #include "diagnostic-core.h"
112 #include "hash-set.h"
114 #include "machmode.h"
115 #include "hard-reg-set.h"
117 #include "function.h"
118 #include "insn-config.h"
119 #include "conditions.h"
120 #include "basic-block.h"
125 #include "insn-attr.h"
126 #include "resource.h"
130 #include "tree-pass.h"
131 #include "emit-rtl.h"
135 #ifndef ANNUL_IFTRUE_SLOTS
136 #define eligible_for_annul_true(INSN, SLOTS, TRIAL, FLAGS) 0
138 #ifndef ANNUL_IFFALSE_SLOTS
139 #define eligible_for_annul_false(INSN, SLOTS, TRIAL, FLAGS) 0
143 /* First, some functions that were used before GCC got a control flow graph.
144 These functions are now only used here in reorg.c, and have therefore
145 been moved here to avoid inadvertent misuse elsewhere in the compiler. */
147 /* Return the last label to mark the same position as LABEL. Return LABEL
148 itself if it is null or any return rtx. */
151 skip_consecutive_labels (rtx label_or_return
)
155 if (label_or_return
&& ANY_RETURN_P (label_or_return
))
156 return label_or_return
;
158 rtx_insn
*label
= as_a
<rtx_insn
*> (label_or_return
);
160 for (insn
= label
; insn
!= 0 && !INSN_P (insn
); insn
= NEXT_INSN (insn
))
168 /* INSN uses CC0 and is being moved into a delay slot. Set up REG_CC_SETTER
169 and REG_CC_USER notes so we can find it. */
172 link_cc0_insns (rtx insn
)
174 rtx user
= next_nonnote_insn (insn
);
176 if (NONJUMP_INSN_P (user
) && GET_CODE (PATTERN (user
)) == SEQUENCE
)
177 user
= XVECEXP (PATTERN (user
), 0, 0);
179 add_reg_note (user
, REG_CC_SETTER
, insn
);
180 add_reg_note (insn
, REG_CC_USER
, user
);
184 /* Insns which have delay slots that have not yet been filled. */
186 static struct obstack unfilled_slots_obstack
;
187 static rtx
*unfilled_firstobj
;
189 /* Define macros to refer to the first and last slot containing unfilled
190 insns. These are used because the list may move and its address
191 should be recomputed at each use. */
193 #define unfilled_slots_base \
194 ((rtx_insn **) obstack_base (&unfilled_slots_obstack))
196 #define unfilled_slots_next \
197 ((rtx_insn **) obstack_next_free (&unfilled_slots_obstack))
199 /* Points to the label before the end of the function, or before a
201 static rtx_code_label
*function_return_label
;
202 /* Likewise for a simple_return. */
203 static rtx_code_label
*function_simple_return_label
;
205 /* Mapping between INSN_UID's and position in the code since INSN_UID's do
206 not always monotonically increase. */
207 static int *uid_to_ruid
;
209 /* Highest valid index in `uid_to_ruid'. */
212 static int stop_search_p (rtx
, int);
213 static int resource_conflicts_p (struct resources
*, struct resources
*);
214 static int insn_references_resource_p (rtx
, struct resources
*, bool);
215 static int insn_sets_resource_p (rtx
, struct resources
*, bool);
216 static rtx_code_label
*find_end_label (rtx
);
217 static rtx_insn
*emit_delay_sequence (rtx_insn
*, rtx_insn_list
*, int);
218 static rtx_insn_list
*add_to_delay_list (rtx_insn
*, rtx_insn_list
*);
219 static rtx_insn
*delete_from_delay_slot (rtx_insn
*);
220 static void delete_scheduled_jump (rtx_insn
*);
221 static void note_delay_statistics (int, int);
222 #if defined(ANNUL_IFFALSE_SLOTS) || defined(ANNUL_IFTRUE_SLOTS)
223 static rtx_insn_list
*optimize_skip (rtx_insn
*);
225 static int get_jump_flags (const rtx_insn
*, rtx
);
226 static int mostly_true_jump (rtx
);
227 static rtx
get_branch_condition (const rtx_insn
*, rtx
);
228 static int condition_dominates_p (rtx
, const rtx_insn
*);
229 static int redirect_with_delay_slots_safe_p (rtx_insn
*, rtx
, rtx
);
230 static int redirect_with_delay_list_safe_p (rtx_insn
*, rtx
, rtx_insn_list
*);
231 static int check_annul_list_true_false (int, rtx
);
232 static rtx_insn_list
*steal_delay_list_from_target (rtx_insn
*, rtx
,
240 static rtx_insn_list
*steal_delay_list_from_fallthrough (rtx_insn
*, rtx
,
247 static void try_merge_delay_insns (rtx
, rtx_insn
*);
248 static rtx
redundant_insn (rtx
, rtx_insn
*, rtx
);
249 static int own_thread_p (rtx
, rtx
, int);
250 static void update_block (rtx_insn
*, rtx
);
251 static int reorg_redirect_jump (rtx_insn
*, rtx
);
252 static void update_reg_dead_notes (rtx
, rtx
);
253 static void fix_reg_dead_note (rtx
, rtx
);
254 static void update_reg_unused_notes (rtx
, rtx
);
255 static void fill_simple_delay_slots (int);
256 static rtx_insn_list
*fill_slots_from_thread (rtx_insn
*, rtx
, rtx
, rtx
,
258 int *, rtx_insn_list
*);
259 static void fill_eager_delay_slots (void);
260 static void relax_delay_slots (rtx_insn
*);
261 static void make_return_insns (rtx_insn
*);
263 /* A wrapper around next_active_insn which takes care to return ret_rtx
267 first_active_target_insn (rtx insn
)
269 if (ANY_RETURN_P (insn
))
271 return next_active_insn (as_a
<rtx_insn
*> (insn
));
274 /* Return true iff INSN is a simplejump, or any kind of return insn. */
277 simplejump_or_return_p (rtx insn
)
279 return (JUMP_P (insn
)
280 && (simplejump_p (as_a
<rtx_insn
*> (insn
))
281 || ANY_RETURN_P (PATTERN (insn
))));
284 /* Return TRUE if this insn should stop the search for insn to fill delay
285 slots. LABELS_P indicates that labels should terminate the search.
286 In all cases, jumps terminate the search. */
289 stop_search_p (rtx insn
, int labels_p
)
294 /* If the insn can throw an exception that is caught within the function,
295 it may effectively perform a jump from the viewpoint of the function.
296 Therefore act like for a jump. */
297 if (can_throw_internal (insn
))
300 switch (GET_CODE (insn
))
314 /* OK unless it contains a delay slot or is an `asm' insn of some type.
315 We don't know anything about these. */
316 return (GET_CODE (PATTERN (insn
)) == SEQUENCE
317 || GET_CODE (PATTERN (insn
)) == ASM_INPUT
318 || asm_noperands (PATTERN (insn
)) >= 0);
325 /* Return TRUE if any resources are marked in both RES1 and RES2 or if either
326 resource set contains a volatile memory reference. Otherwise, return FALSE. */
329 resource_conflicts_p (struct resources
*res1
, struct resources
*res2
)
331 if ((res1
->cc
&& res2
->cc
) || (res1
->memory
&& res2
->memory
)
332 || res1
->volatil
|| res2
->volatil
)
335 return hard_reg_set_intersect_p (res1
->regs
, res2
->regs
);
338 /* Return TRUE if any resource marked in RES, a `struct resources', is
339 referenced by INSN. If INCLUDE_DELAYED_EFFECTS is set, return if the called
340 routine is using those resources.
342 We compute this by computing all the resources referenced by INSN and
343 seeing if this conflicts with RES. It might be faster to directly check
344 ourselves, and this is the way it used to work, but it means duplicating
345 a large block of complex code. */
348 insn_references_resource_p (rtx insn
, struct resources
*res
,
349 bool include_delayed_effects
)
351 struct resources insn_res
;
353 CLEAR_RESOURCE (&insn_res
);
354 mark_referenced_resources (insn
, &insn_res
, include_delayed_effects
);
355 return resource_conflicts_p (&insn_res
, res
);
358 /* Return TRUE if INSN modifies resources that are marked in RES.
359 INCLUDE_DELAYED_EFFECTS is set if the actions of that routine should be
360 included. CC0 is only modified if it is explicitly set; see comments
361 in front of mark_set_resources for details. */
364 insn_sets_resource_p (rtx insn
, struct resources
*res
,
365 bool include_delayed_effects
)
367 struct resources insn_sets
;
369 CLEAR_RESOURCE (&insn_sets
);
370 mark_set_resources (insn
, &insn_sets
, 0,
371 (include_delayed_effects
374 return resource_conflicts_p (&insn_sets
, res
);
377 /* Find a label at the end of the function or before a RETURN. If there
378 is none, try to make one. If that fails, returns 0.
380 The property of such a label is that it is placed just before the
381 epilogue or a bare RETURN insn, so that another bare RETURN can be
382 turned into a jump to the label unconditionally. In particular, the
383 label cannot be placed before a RETURN insn with a filled delay slot.
385 ??? There may be a problem with the current implementation. Suppose
386 we start with a bare RETURN insn and call find_end_label. It may set
387 function_return_label just before the RETURN. Suppose the machinery
388 is able to fill the delay slot of the RETURN insn afterwards. Then
389 function_return_label is no longer valid according to the property
390 described above and find_end_label will still return it unmodified.
391 Note that this is probably mitigated by the following observation:
392 once function_return_label is made, it is very likely the target of
393 a jump, so filling the delay slot of the RETURN will be much more
395 KIND is either simple_return_rtx or ret_rtx, indicating which type of
396 return we're looking for. */
398 static rtx_code_label
*
399 find_end_label (rtx kind
)
402 rtx_code_label
**plabel
;
405 plabel
= &function_return_label
;
408 gcc_assert (kind
== simple_return_rtx
);
409 plabel
= &function_simple_return_label
;
412 /* If we found one previously, return it. */
416 /* Otherwise, see if there is a label at the end of the function. If there
417 is, it must be that RETURN insns aren't needed, so that is our return
418 label and we don't have to do anything else. */
420 insn
= get_last_insn ();
422 || (NONJUMP_INSN_P (insn
)
423 && (GET_CODE (PATTERN (insn
)) == USE
424 || GET_CODE (PATTERN (insn
)) == CLOBBER
)))
425 insn
= PREV_INSN (insn
);
427 /* When a target threads its epilogue we might already have a
428 suitable return insn. If so put a label before it for the
429 function_return_label. */
431 && JUMP_P (PREV_INSN (insn
))
432 && PATTERN (PREV_INSN (insn
)) == kind
)
434 rtx_insn
*temp
= PREV_INSN (PREV_INSN (insn
));
435 rtx_code_label
*label
= gen_label_rtx ();
436 LABEL_NUSES (label
) = 0;
438 /* Put the label before any USE insns that may precede the RETURN
440 while (GET_CODE (temp
) == USE
)
441 temp
= PREV_INSN (temp
);
443 emit_label_after (label
, temp
);
447 else if (LABEL_P (insn
))
448 *plabel
= as_a
<rtx_code_label
*> (insn
);
451 rtx_code_label
*label
= gen_label_rtx ();
452 LABEL_NUSES (label
) = 0;
453 /* If the basic block reorder pass moves the return insn to
454 some other place try to locate it again and put our
455 function_return_label there. */
456 while (insn
&& ! (JUMP_P (insn
) && (PATTERN (insn
) == kind
)))
457 insn
= PREV_INSN (insn
);
460 insn
= PREV_INSN (insn
);
462 /* Put the label before any USE insns that may precede the
464 while (GET_CODE (insn
) == USE
)
465 insn
= PREV_INSN (insn
);
467 emit_label_after (label
, insn
);
477 /* The RETURN insn has its delay slot filled so we cannot
478 emit the label just before it. Since we already have
479 an epilogue and cannot emit a new RETURN, we cannot
480 emit the label at all. */
482 #endif /* HAVE_epilogue */
484 /* Otherwise, make a new label and emit a RETURN and BARRIER,
490 /* The return we make may have delay slots too. */
491 rtx pat
= gen_return ();
492 rtx_insn
*insn
= emit_jump_insn (pat
);
493 set_return_jump_label (insn
);
495 if (num_delay_slots (insn
) > 0)
496 obstack_ptr_grow (&unfilled_slots_obstack
, insn
);
503 /* Show one additional use for this label so it won't go away until
505 ++LABEL_NUSES (*plabel
);
510 /* Put INSN and LIST together in a SEQUENCE rtx of LENGTH, and replace
511 the pattern of INSN with the SEQUENCE.
513 Returns the insn containing the SEQUENCE that replaces INSN. */
516 emit_delay_sequence (rtx_insn
*insn
, rtx_insn_list
*list
, int length
)
518 /* Allocate the rtvec to hold the insns and the SEQUENCE. */
519 rtvec seqv
= rtvec_alloc (length
+ 1);
520 rtx seq
= gen_rtx_SEQUENCE (VOIDmode
, seqv
);
521 rtx_insn
*seq_insn
= make_insn_raw (seq
);
523 /* If DELAY_INSN has a location, use it for SEQ_INSN. If DELAY_INSN does
524 not have a location, but one of the delayed insns does, we pick up a
525 location from there later. */
526 INSN_LOCATION (seq_insn
) = INSN_LOCATION (insn
);
528 /* Unlink INSN from the insn chain, so that we can put it into
529 the SEQUENCE. Remember where we want to emit SEQUENCE in AFTER. */
530 rtx after
= PREV_INSN (insn
);
532 SET_NEXT_INSN (insn
) = SET_PREV_INSN (insn
) = NULL
;
534 /* Build our SEQUENCE and rebuild the insn chain. */
537 XVECEXP (seq
, 0, 0) = emit_insn (insn
);
538 for (rtx_insn_list
*li
= list
; li
; li
= li
->next (), i
++)
540 rtx_insn
*tem
= li
->insn ();
543 /* Show that this copy of the insn isn't deleted. */
544 tem
->set_undeleted ();
546 /* Unlink insn from its original place, and re-emit it into
548 SET_NEXT_INSN (tem
) = SET_PREV_INSN (tem
) = NULL
;
549 XVECEXP (seq
, 0, i
) = emit_insn (tem
);
551 /* SPARC assembler, for instance, emit warning when debug info is output
552 into the delay slot. */
553 if (INSN_LOCATION (tem
) && !INSN_LOCATION (seq_insn
))
554 INSN_LOCATION (seq_insn
) = INSN_LOCATION (tem
);
555 INSN_LOCATION (tem
) = 0;
557 for (note
= REG_NOTES (tem
); note
; note
= next
)
559 next
= XEXP (note
, 1);
560 switch (REG_NOTE_KIND (note
))
563 /* Remove any REG_DEAD notes because we can't rely on them now
564 that the insn has been moved. */
565 remove_note (tem
, note
);
568 case REG_LABEL_OPERAND
:
569 case REG_LABEL_TARGET
:
570 /* Keep the label reference count up to date. */
571 if (LABEL_P (XEXP (note
, 0)))
572 LABEL_NUSES (XEXP (note
, 0)) ++;
581 gcc_assert (i
== length
+ 1);
583 /* Splice our SEQUENCE into the insn stream where INSN used to be. */
584 add_insn_after (seq_insn
, after
, NULL
);
589 /* Add INSN to DELAY_LIST and return the head of the new list. The list must
590 be in the order in which the insns are to be executed. */
592 static rtx_insn_list
*
593 add_to_delay_list (rtx_insn
*insn
, rtx_insn_list
*delay_list
)
595 /* If we have an empty list, just make a new list element. If
596 INSN has its block number recorded, clear it since we may
597 be moving the insn to a new block. */
601 clear_hashed_info_for_insn (insn
);
602 return gen_rtx_INSN_LIST (VOIDmode
, insn
, NULL_RTX
);
605 /* Otherwise this must be an INSN_LIST. Add INSN to the end of the
607 XEXP (delay_list
, 1) = add_to_delay_list (insn
, delay_list
->next ());
612 /* Delete INSN from the delay slot of the insn that it is in, which may
613 produce an insn with no delay slots. Return the new insn. */
616 delete_from_delay_slot (rtx_insn
*insn
)
618 rtx_insn
*trial
, *seq_insn
, *prev
;
620 rtx_insn_list
*delay_list
= 0;
624 /* We first must find the insn containing the SEQUENCE with INSN in its
625 delay slot. Do this by finding an insn, TRIAL, where
626 PREV_INSN (NEXT_INSN (TRIAL)) != TRIAL. */
629 PREV_INSN (NEXT_INSN (trial
)) == trial
;
630 trial
= NEXT_INSN (trial
))
633 seq_insn
= PREV_INSN (NEXT_INSN (trial
));
634 seq
= as_a
<rtx_sequence
*> (PATTERN (seq_insn
));
636 if (NEXT_INSN (seq_insn
) && BARRIER_P (NEXT_INSN (seq_insn
)))
639 /* Create a delay list consisting of all the insns other than the one
640 we are deleting (unless we were the only one). */
642 for (i
= 1; i
< seq
->len (); i
++)
643 if (seq
->insn (i
) != insn
)
644 delay_list
= add_to_delay_list (seq
->insn (i
), delay_list
);
646 /* Delete the old SEQUENCE, re-emit the insn that used to have the delay
647 list, and rebuild the delay list if non-empty. */
648 prev
= PREV_INSN (seq_insn
);
649 trial
= seq
->insn (0);
650 delete_related_insns (seq_insn
);
651 add_insn_after (trial
, prev
, NULL
);
653 /* If there was a barrier after the old SEQUENCE, remit it. */
655 emit_barrier_after (trial
);
657 /* If there are any delay insns, remit them. Otherwise clear the
660 trial
= emit_delay_sequence (trial
, delay_list
, XVECLEN (seq
, 0) - 2);
661 else if (JUMP_P (trial
))
662 INSN_ANNULLED_BRANCH_P (trial
) = 0;
664 INSN_FROM_TARGET_P (insn
) = 0;
666 /* Show we need to fill this insn again. */
667 obstack_ptr_grow (&unfilled_slots_obstack
, trial
);
672 /* Delete INSN, a JUMP_INSN. If it is a conditional jump, we must track down
673 the insn that sets CC0 for it and delete it too. */
676 delete_scheduled_jump (rtx_insn
*insn
)
678 /* Delete the insn that sets cc0 for us. On machines without cc0, we could
679 delete the insn that sets the condition code, but it is hard to find it.
680 Since this case is rare anyway, don't bother trying; there would likely
681 be other insns that became dead anyway, which we wouldn't know to
685 if (reg_mentioned_p (cc0_rtx
, insn
))
687 rtx note
= find_reg_note (insn
, REG_CC_SETTER
, NULL_RTX
);
689 /* If a reg-note was found, it points to an insn to set CC0. This
690 insn is in the delay list of some other insn. So delete it from
691 the delay list it was in. */
694 if (! FIND_REG_INC_NOTE (XEXP (note
, 0), NULL_RTX
)
695 && sets_cc0_p (PATTERN (XEXP (note
, 0))) == 1)
696 delete_from_delay_slot (as_a
<rtx_insn
*> (XEXP (note
, 0)));
700 /* The insn setting CC0 is our previous insn, but it may be in
701 a delay slot. It will be the last insn in the delay slot, if
703 rtx_insn
*trial
= previous_insn (insn
);
705 trial
= prev_nonnote_insn (trial
);
706 if (sets_cc0_p (PATTERN (trial
)) != 1
707 || FIND_REG_INC_NOTE (trial
, NULL_RTX
))
709 if (PREV_INSN (NEXT_INSN (trial
)) == trial
)
710 delete_related_insns (trial
);
712 delete_from_delay_slot (trial
);
717 delete_related_insns (insn
);
720 /* Counters for delay-slot filling. */
722 #define NUM_REORG_FUNCTIONS 2
723 #define MAX_DELAY_HISTOGRAM 3
724 #define MAX_REORG_PASSES 2
726 static int num_insns_needing_delays
[NUM_REORG_FUNCTIONS
][MAX_REORG_PASSES
];
728 static int num_filled_delays
[NUM_REORG_FUNCTIONS
][MAX_DELAY_HISTOGRAM
+1][MAX_REORG_PASSES
];
730 static int reorg_pass_number
;
733 note_delay_statistics (int slots_filled
, int index
)
735 num_insns_needing_delays
[index
][reorg_pass_number
]++;
736 if (slots_filled
> MAX_DELAY_HISTOGRAM
)
737 slots_filled
= MAX_DELAY_HISTOGRAM
;
738 num_filled_delays
[index
][slots_filled
][reorg_pass_number
]++;
741 #if defined(ANNUL_IFFALSE_SLOTS) || defined(ANNUL_IFTRUE_SLOTS)
743 /* Optimize the following cases:
745 1. When a conditional branch skips over only one instruction,
746 use an annulling branch and put that insn in the delay slot.
747 Use either a branch that annuls when the condition if true or
748 invert the test with a branch that annuls when the condition is
749 false. This saves insns, since otherwise we must copy an insn
752 (orig) (skip) (otherwise)
753 Bcc.n L1 Bcc',a L1 Bcc,a L1'
760 2. When a conditional branch skips over only one instruction,
761 and after that, it unconditionally branches somewhere else,
762 perform the similar optimization. This saves executing the
763 second branch in the case where the inverted condition is true.
772 This should be expanded to skip over N insns, where N is the number
773 of delay slots required. */
775 static rtx_insn_list
*
776 optimize_skip (rtx_insn
*insn
)
778 rtx_insn
*trial
= next_nonnote_insn (insn
);
779 rtx_insn
*next_trial
= next_active_insn (trial
);
780 rtx_insn_list
*delay_list
= 0;
783 flags
= get_jump_flags (insn
, JUMP_LABEL (insn
));
786 || !NONJUMP_INSN_P (trial
)
787 || GET_CODE (PATTERN (trial
)) == SEQUENCE
788 || recog_memoized (trial
) < 0
789 || (! eligible_for_annul_false (insn
, 0, trial
, flags
)
790 && ! eligible_for_annul_true (insn
, 0, trial
, flags
))
791 || can_throw_internal (trial
))
794 /* There are two cases where we are just executing one insn (we assume
795 here that a branch requires only one insn; this should be generalized
796 at some point): Where the branch goes around a single insn or where
797 we have one insn followed by a branch to the same label we branch to.
798 In both of these cases, inverting the jump and annulling the delay
799 slot give the same effect in fewer insns. */
800 if (next_trial
== next_active_insn (JUMP_LABEL (insn
))
802 && simplejump_or_return_p (next_trial
)
803 && JUMP_LABEL (insn
) == JUMP_LABEL (next_trial
)))
805 if (eligible_for_annul_false (insn
, 0, trial
, flags
))
807 if (invert_jump (insn
, JUMP_LABEL (insn
), 1))
808 INSN_FROM_TARGET_P (trial
) = 1;
809 else if (! eligible_for_annul_true (insn
, 0, trial
, flags
))
813 delay_list
= add_to_delay_list (trial
, NULL
);
814 next_trial
= next_active_insn (trial
);
815 update_block (trial
, trial
);
816 delete_related_insns (trial
);
818 /* Also, if we are targeting an unconditional
819 branch, thread our jump to the target of that branch. Don't
820 change this into a RETURN here, because it may not accept what
821 we have in the delay slot. We'll fix this up later. */
822 if (next_trial
&& simplejump_or_return_p (next_trial
))
824 rtx target_label
= JUMP_LABEL (next_trial
);
825 if (ANY_RETURN_P (target_label
))
826 target_label
= find_end_label (target_label
);
830 /* Recompute the flags based on TARGET_LABEL since threading
831 the jump to TARGET_LABEL may change the direction of the
832 jump (which may change the circumstances in which the
833 delay slot is nullified). */
834 flags
= get_jump_flags (insn
, target_label
);
835 if (eligible_for_annul_true (insn
, 0, trial
, flags
))
836 reorg_redirect_jump (insn
, target_label
);
840 INSN_ANNULLED_BRANCH_P (insn
) = 1;
847 /* Encode and return branch direction and prediction information for
848 INSN assuming it will jump to LABEL.
850 Non conditional branches return no direction information and
851 are predicted as very likely taken. */
854 get_jump_flags (const rtx_insn
*insn
, rtx label
)
858 /* get_jump_flags can be passed any insn with delay slots, these may
859 be INSNs, CALL_INSNs, or JUMP_INSNs. Only JUMP_INSNs have branch
860 direction information, and only if they are conditional jumps.
862 If LABEL is a return, then there is no way to determine the branch
865 && (condjump_p (insn
) || condjump_in_parallel_p (insn
))
866 && !ANY_RETURN_P (label
)
867 && INSN_UID (insn
) <= max_uid
868 && INSN_UID (label
) <= max_uid
)
870 = (uid_to_ruid
[INSN_UID (label
)] > uid_to_ruid
[INSN_UID (insn
)])
871 ? ATTR_FLAG_forward
: ATTR_FLAG_backward
;
872 /* No valid direction information. */
879 /* Return truth value of the statement that this branch
880 is mostly taken. If we think that the branch is extremely likely
881 to be taken, we return 2. If the branch is slightly more likely to be
882 taken, return 1. If the branch is slightly less likely to be taken,
883 return 0 and if the branch is highly unlikely to be taken, return -1. */
886 mostly_true_jump (rtx jump_insn
)
888 /* If branch probabilities are available, then use that number since it
889 always gives a correct answer. */
890 rtx note
= find_reg_note (jump_insn
, REG_BR_PROB
, 0);
893 int prob
= XINT (note
, 0);
895 if (prob
>= REG_BR_PROB_BASE
* 9 / 10)
897 else if (prob
>= REG_BR_PROB_BASE
/ 2)
899 else if (prob
>= REG_BR_PROB_BASE
/ 10)
905 /* If there is no note, assume branches are not taken.
906 This should be rare. */
910 /* Return the condition under which INSN will branch to TARGET. If TARGET
911 is zero, return the condition under which INSN will return. If INSN is
912 an unconditional branch, return const_true_rtx. If INSN isn't a simple
913 type of jump, or it doesn't go to TARGET, return 0. */
916 get_branch_condition (const rtx_insn
*insn
, rtx target
)
918 rtx pat
= PATTERN (insn
);
921 if (condjump_in_parallel_p (insn
))
922 pat
= XVECEXP (pat
, 0, 0);
924 if (ANY_RETURN_P (pat
) && pat
== target
)
925 return const_true_rtx
;
927 if (GET_CODE (pat
) != SET
|| SET_DEST (pat
) != pc_rtx
)
931 if (GET_CODE (src
) == LABEL_REF
&& LABEL_REF_LABEL (src
) == target
)
932 return const_true_rtx
;
934 else if (GET_CODE (src
) == IF_THEN_ELSE
935 && XEXP (src
, 2) == pc_rtx
936 && ((GET_CODE (XEXP (src
, 1)) == LABEL_REF
937 && LABEL_REF_LABEL (XEXP (src
, 1)) == target
)
938 || (ANY_RETURN_P (XEXP (src
, 1)) && XEXP (src
, 1) == target
)))
939 return XEXP (src
, 0);
941 else if (GET_CODE (src
) == IF_THEN_ELSE
942 && XEXP (src
, 1) == pc_rtx
943 && ((GET_CODE (XEXP (src
, 2)) == LABEL_REF
944 && LABEL_REF_LABEL (XEXP (src
, 2)) == target
)
945 || (ANY_RETURN_P (XEXP (src
, 2)) && XEXP (src
, 2) == target
)))
948 rev
= reversed_comparison_code (XEXP (src
, 0), insn
);
950 return gen_rtx_fmt_ee (rev
, GET_MODE (XEXP (src
, 0)),
951 XEXP (XEXP (src
, 0), 0),
952 XEXP (XEXP (src
, 0), 1));
958 /* Return nonzero if CONDITION is more strict than the condition of
959 INSN, i.e., if INSN will always branch if CONDITION is true. */
962 condition_dominates_p (rtx condition
, const rtx_insn
*insn
)
964 rtx other_condition
= get_branch_condition (insn
, JUMP_LABEL (insn
));
965 enum rtx_code code
= GET_CODE (condition
);
966 enum rtx_code other_code
;
968 if (rtx_equal_p (condition
, other_condition
)
969 || other_condition
== const_true_rtx
)
972 else if (condition
== const_true_rtx
|| other_condition
== 0)
975 other_code
= GET_CODE (other_condition
);
976 if (GET_RTX_LENGTH (code
) != 2 || GET_RTX_LENGTH (other_code
) != 2
977 || ! rtx_equal_p (XEXP (condition
, 0), XEXP (other_condition
, 0))
978 || ! rtx_equal_p (XEXP (condition
, 1), XEXP (other_condition
, 1)))
981 return comparison_dominates_p (code
, other_code
);
984 /* Return nonzero if redirecting JUMP to NEWLABEL does not invalidate
985 any insns already in the delay slot of JUMP. */
988 redirect_with_delay_slots_safe_p (rtx_insn
*jump
, rtx newlabel
, rtx seq
)
991 rtx_sequence
*pat
= as_a
<rtx_sequence
*> (PATTERN (seq
));
993 /* Make sure all the delay slots of this jump would still
994 be valid after threading the jump. If they are still
995 valid, then return nonzero. */
997 flags
= get_jump_flags (jump
, newlabel
);
998 for (i
= 1; i
< pat
->len (); i
++)
1000 #ifdef ANNUL_IFFALSE_SLOTS
1001 (INSN_ANNULLED_BRANCH_P (jump
)
1002 && INSN_FROM_TARGET_P (pat
->insn (i
)))
1003 ? eligible_for_annul_false (jump
, i
- 1, pat
->insn (i
), flags
) :
1005 #ifdef ANNUL_IFTRUE_SLOTS
1006 (INSN_ANNULLED_BRANCH_P (jump
)
1007 && ! INSN_FROM_TARGET_P (XVECEXP (pat
, 0, i
)))
1008 ? eligible_for_annul_true (jump
, i
- 1, pat
->insn (i
), flags
) :
1010 eligible_for_delay (jump
, i
- 1, pat
->insn (i
), flags
)))
1013 return (i
== pat
->len ());
1016 /* Return nonzero if redirecting JUMP to NEWLABEL does not invalidate
1017 any insns we wish to place in the delay slot of JUMP. */
1020 redirect_with_delay_list_safe_p (rtx_insn
*jump
, rtx newlabel
,
1021 rtx_insn_list
*delay_list
)
1026 /* Make sure all the insns in DELAY_LIST would still be
1027 valid after threading the jump. If they are still
1028 valid, then return nonzero. */
1030 flags
= get_jump_flags (jump
, newlabel
);
1031 for (li
= delay_list
, i
= 0; li
; li
= li
->next (), i
++)
1033 #ifdef ANNUL_IFFALSE_SLOTS
1034 (INSN_ANNULLED_BRANCH_P (jump
)
1035 && INSN_FROM_TARGET_P (li
->insn ()))
1036 ? eligible_for_annul_false (jump
, i
, li
->insn (), flags
) :
1038 #ifdef ANNUL_IFTRUE_SLOTS
1039 (INSN_ANNULLED_BRANCH_P (jump
)
1040 && ! INSN_FROM_TARGET_P (XEXP (li
, 0)))
1041 ? eligible_for_annul_true (jump
, i
, li
->insn (), flags
) :
1043 eligible_for_delay (jump
, i
, li
->insn (), flags
)))
1046 return (li
== NULL
);
1049 /* DELAY_LIST is a list of insns that have already been placed into delay
1050 slots. See if all of them have the same annulling status as ANNUL_TRUE_P.
1051 If not, return 0; otherwise return 1. */
1054 check_annul_list_true_false (int annul_true_p
, rtx delay_list
)
1060 for (temp
= delay_list
; temp
; temp
= XEXP (temp
, 1))
1062 rtx trial
= XEXP (temp
, 0);
1064 if ((annul_true_p
&& INSN_FROM_TARGET_P (trial
))
1065 || (!annul_true_p
&& !INSN_FROM_TARGET_P (trial
)))
1073 /* INSN branches to an insn whose pattern SEQ is a SEQUENCE. Given that
1074 the condition tested by INSN is CONDITION and the resources shown in
1075 OTHER_NEEDED are needed after INSN, see whether INSN can take all the insns
1076 from SEQ's delay list, in addition to whatever insns it may execute
1077 (in DELAY_LIST). SETS and NEEDED are denote resources already set and
1078 needed while searching for delay slot insns. Return the concatenated
1079 delay list if possible, otherwise, return 0.
1081 SLOTS_TO_FILL is the total number of slots required by INSN, and
1082 PSLOTS_FILLED points to the number filled so far (also the number of
1083 insns in DELAY_LIST). It is updated with the number that have been
1084 filled from the SEQUENCE, if any.
1086 PANNUL_P points to a nonzero value if we already know that we need
1087 to annul INSN. If this routine determines that annulling is needed,
1088 it may set that value nonzero.
1090 PNEW_THREAD points to a location that is to receive the place at which
1091 execution should continue. */
1093 static rtx_insn_list
*
1094 steal_delay_list_from_target (rtx_insn
*insn
, rtx condition
, rtx_sequence
*seq
,
1095 rtx_insn_list
*delay_list
, struct resources
*sets
,
1096 struct resources
*needed
,
1097 struct resources
*other_needed
,
1098 int slots_to_fill
, int *pslots_filled
,
1099 int *pannul_p
, rtx
*pnew_thread
)
1101 int slots_remaining
= slots_to_fill
- *pslots_filled
;
1102 int total_slots_filled
= *pslots_filled
;
1103 rtx_insn_list
*new_delay_list
= 0;
1104 int must_annul
= *pannul_p
;
1107 struct resources cc_set
;
1110 /* We can't do anything if there are more delay slots in SEQ than we
1111 can handle, or if we don't know that it will be a taken branch.
1112 We know that it will be a taken branch if it is either an unconditional
1113 branch or a conditional branch with a stricter branch condition.
1115 Also, exit if the branch has more than one set, since then it is computing
1116 other results that can't be ignored, e.g. the HPPA mov&branch instruction.
1117 ??? It may be possible to move other sets into INSN in addition to
1118 moving the instructions in the delay slots.
1120 We can not steal the delay list if one of the instructions in the
1121 current delay_list modifies the condition codes and the jump in the
1122 sequence is a conditional jump. We can not do this because we can
1123 not change the direction of the jump because the condition codes
1124 will effect the direction of the jump in the sequence. */
1126 CLEAR_RESOURCE (&cc_set
);
1127 for (rtx_insn_list
*temp
= delay_list
; temp
; temp
= temp
->next ())
1129 rtx_insn
*trial
= temp
->insn ();
1131 mark_set_resources (trial
, &cc_set
, 0, MARK_SRC_DEST_CALL
);
1132 if (insn_references_resource_p (seq
->insn (0), &cc_set
, false))
1136 if (XVECLEN (seq
, 0) - 1 > slots_remaining
1137 || ! condition_dominates_p (condition
, seq
->insn (0))
1138 || ! single_set (seq
->insn (0)))
1141 #ifdef MD_CAN_REDIRECT_BRANCH
1142 /* On some targets, branches with delay slots can have a limited
1143 displacement. Give the back end a chance to tell us we can't do
1145 if (! MD_CAN_REDIRECT_BRANCH (insn
, seq
->insn (0)))
1149 redundant
= XALLOCAVEC (bool, XVECLEN (seq
, 0));
1150 for (i
= 1; i
< seq
->len (); i
++)
1152 rtx_insn
*trial
= seq
->insn (i
);
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)
1159 /* If TRIAL sets CC0, we can't copy it, so we can't steal this
1161 || find_reg_note (trial
, REG_CC_USER
, NULL_RTX
)
1163 /* If TRIAL is from the fallthrough code of an annulled branch insn
1164 in SEQ, we cannot use it. */
1165 || (INSN_ANNULLED_BRANCH_P (seq
->insn (0))
1166 && ! INSN_FROM_TARGET_P (trial
)))
1169 /* If this insn was already done (usually in a previous delay slot),
1170 pretend we put it in our delay slot. */
1171 redundant
[i
] = redundant_insn (trial
, insn
, new_delay_list
);
1175 /* We will end up re-vectoring this branch, so compute flags
1176 based on jumping to the new label. */
1177 flags
= get_jump_flags (insn
, JUMP_LABEL (seq
->insn (0)));
1180 && ((condition
== const_true_rtx
1181 || (! insn_sets_resource_p (trial
, other_needed
, false)
1182 && ! may_trap_or_fault_p (PATTERN (trial
)))))
1183 ? eligible_for_delay (insn
, total_slots_filled
, trial
, flags
)
1184 : (must_annul
|| (delay_list
== NULL
&& new_delay_list
== NULL
))
1186 check_annul_list_true_false (0, delay_list
)
1187 && check_annul_list_true_false (0, new_delay_list
)
1188 && eligible_for_annul_false (insn
, total_slots_filled
,
1193 rtx_insn
*temp
= copy_delay_slot_insn (trial
);
1194 INSN_FROM_TARGET_P (temp
) = 1;
1195 new_delay_list
= add_to_delay_list (temp
, new_delay_list
);
1196 total_slots_filled
++;
1198 if (--slots_remaining
== 0)
1205 /* Record the effect of the instructions that were redundant and which
1206 we therefore decided not to copy. */
1207 for (i
= 1; i
< seq
->len (); i
++)
1209 update_block (seq
->insn (i
), insn
);
1211 /* Show the place to which we will be branching. */
1212 *pnew_thread
= first_active_target_insn (JUMP_LABEL (seq
->insn (0)));
1214 /* Add any new insns to the delay list and update the count of the
1215 number of slots filled. */
1216 *pslots_filled
= total_slots_filled
;
1220 if (delay_list
== 0)
1221 return new_delay_list
;
1223 for (rtx_insn_list
*temp
= new_delay_list
; temp
; temp
= temp
->next ())
1224 delay_list
= add_to_delay_list (temp
->insn (), delay_list
);
1229 /* Similar to steal_delay_list_from_target except that SEQ is on the
1230 fallthrough path of INSN. Here we only do something if the delay insn
1231 of SEQ is an unconditional branch. In that case we steal its delay slot
1232 for INSN since unconditional branches are much easier to fill. */
1234 static rtx_insn_list
*
1235 steal_delay_list_from_fallthrough (rtx_insn
*insn
, rtx condition
,
1237 rtx_insn_list
*delay_list
,
1238 struct resources
*sets
,
1239 struct resources
*needed
,
1240 struct resources
*other_needed
,
1241 int slots_to_fill
, int *pslots_filled
,
1246 int must_annul
= *pannul_p
;
1249 flags
= get_jump_flags (insn
, JUMP_LABEL (insn
));
1251 /* We can't do anything if SEQ's delay insn isn't an
1252 unconditional branch. */
1254 if (! simplejump_or_return_p (seq
->insn (0)))
1257 for (i
= 1; i
< seq
->len (); i
++)
1259 rtx_insn
*trial
= seq
->insn (i
);
1261 /* If TRIAL sets CC0, stealing it will move it too far from the use
1263 if (insn_references_resource_p (trial
, sets
, false)
1264 || insn_sets_resource_p (trial
, needed
, false)
1265 || insn_sets_resource_p (trial
, sets
, false)
1267 || sets_cc0_p (PATTERN (trial
))
1273 /* If this insn was already done, we don't need it. */
1274 if (redundant_insn (trial
, insn
, delay_list
))
1276 update_block (trial
, insn
);
1277 delete_from_delay_slot (trial
);
1282 && ((condition
== const_true_rtx
1283 || (! insn_sets_resource_p (trial
, other_needed
, false)
1284 && ! may_trap_or_fault_p (PATTERN (trial
)))))
1285 ? eligible_for_delay (insn
, *pslots_filled
, trial
, flags
)
1286 : (must_annul
|| delay_list
== NULL
) && (must_annul
= 1,
1287 check_annul_list_true_false (1, delay_list
)
1288 && eligible_for_annul_true (insn
, *pslots_filled
, trial
, flags
)))
1292 delete_from_delay_slot (trial
);
1293 delay_list
= add_to_delay_list (trial
, delay_list
);
1295 if (++(*pslots_filled
) == slots_to_fill
)
1307 /* Try merging insns starting at THREAD which match exactly the insns in
1310 If all insns were matched and the insn was previously annulling, the
1311 annul bit will be cleared.
1313 For each insn that is merged, if the branch is or will be non-annulling,
1314 we delete the merged insn. */
1317 try_merge_delay_insns (rtx insn
, rtx_insn
*thread
)
1319 rtx_insn
*trial
, *next_trial
;
1320 rtx_insn
*delay_insn
= as_a
<rtx_insn
*> (XVECEXP (PATTERN (insn
), 0, 0));
1321 int annul_p
= JUMP_P (delay_insn
) && INSN_ANNULLED_BRANCH_P (delay_insn
);
1322 int slot_number
= 1;
1323 int num_slots
= XVECLEN (PATTERN (insn
), 0);
1324 rtx next_to_match
= XVECEXP (PATTERN (insn
), 0, slot_number
);
1325 struct resources set
, needed
;
1326 rtx_insn_list
*merged_insns
= 0;
1330 flags
= get_jump_flags (delay_insn
, JUMP_LABEL (delay_insn
));
1332 CLEAR_RESOURCE (&needed
);
1333 CLEAR_RESOURCE (&set
);
1335 /* If this is not an annulling branch, take into account anything needed in
1336 INSN's delay slot. This prevents two increments from being incorrectly
1337 folded into one. If we are annulling, this would be the correct
1338 thing to do. (The alternative, looking at things set in NEXT_TO_MATCH
1339 will essentially disable this optimization. This method is somewhat of
1340 a kludge, but I don't see a better way.) */
1342 for (i
= 1 ; i
< num_slots
; i
++)
1343 if (XVECEXP (PATTERN (insn
), 0, i
))
1344 mark_referenced_resources (XVECEXP (PATTERN (insn
), 0, i
), &needed
,
1347 for (trial
= thread
; !stop_search_p (trial
, 1); trial
= next_trial
)
1349 rtx pat
= PATTERN (trial
);
1350 rtx oldtrial
= trial
;
1352 next_trial
= next_nonnote_insn (trial
);
1354 /* TRIAL must be a CALL_INSN or INSN. Skip USE and CLOBBER. */
1355 if (NONJUMP_INSN_P (trial
)
1356 && (GET_CODE (pat
) == USE
|| GET_CODE (pat
) == CLOBBER
))
1359 if (GET_CODE (next_to_match
) == GET_CODE (trial
)
1361 /* We can't share an insn that sets cc0. */
1362 && ! sets_cc0_p (pat
)
1364 && ! insn_references_resource_p (trial
, &set
, true)
1365 && ! insn_sets_resource_p (trial
, &set
, true)
1366 && ! insn_sets_resource_p (trial
, &needed
, true)
1367 && (trial
= try_split (pat
, trial
, 0)) != 0
1368 /* Update next_trial, in case try_split succeeded. */
1369 && (next_trial
= next_nonnote_insn (trial
))
1370 /* Likewise THREAD. */
1371 && (thread
= oldtrial
== thread
? trial
: thread
)
1372 && rtx_equal_p (PATTERN (next_to_match
), PATTERN (trial
))
1373 /* Have to test this condition if annul condition is different
1374 from (and less restrictive than) non-annulling one. */
1375 && eligible_for_delay (delay_insn
, slot_number
- 1, trial
, flags
))
1380 update_block (trial
, thread
);
1381 if (trial
== thread
)
1382 thread
= next_active_insn (thread
);
1384 delete_related_insns (trial
);
1385 INSN_FROM_TARGET_P (next_to_match
) = 0;
1388 merged_insns
= gen_rtx_INSN_LIST (VOIDmode
, trial
, merged_insns
);
1390 if (++slot_number
== num_slots
)
1393 next_to_match
= XVECEXP (PATTERN (insn
), 0, slot_number
);
1396 mark_set_resources (trial
, &set
, 0, MARK_SRC_DEST_CALL
);
1397 mark_referenced_resources (trial
, &needed
, true);
1400 /* See if we stopped on a filled insn. If we did, try to see if its
1401 delay slots match. */
1402 if (slot_number
!= num_slots
1403 && trial
&& NONJUMP_INSN_P (trial
)
1404 && GET_CODE (PATTERN (trial
)) == SEQUENCE
1405 && !(JUMP_P (XVECEXP (PATTERN (trial
), 0, 0))
1406 && INSN_ANNULLED_BRANCH_P (XVECEXP (PATTERN (trial
), 0, 0))))
1408 rtx_sequence
*pat
= as_a
<rtx_sequence
*> (PATTERN (trial
));
1409 rtx filled_insn
= XVECEXP (pat
, 0, 0);
1411 /* Account for resources set/needed by the filled insn. */
1412 mark_set_resources (filled_insn
, &set
, 0, MARK_SRC_DEST_CALL
);
1413 mark_referenced_resources (filled_insn
, &needed
, true);
1415 for (i
= 1; i
< pat
->len (); i
++)
1417 rtx_insn
*dtrial
= pat
->insn (i
);
1419 if (! insn_references_resource_p (dtrial
, &set
, true)
1420 && ! insn_sets_resource_p (dtrial
, &set
, true)
1421 && ! insn_sets_resource_p (dtrial
, &needed
, true)
1423 && ! sets_cc0_p (PATTERN (dtrial
))
1425 && rtx_equal_p (PATTERN (next_to_match
), PATTERN (dtrial
))
1426 && eligible_for_delay (delay_insn
, slot_number
- 1, dtrial
, flags
))
1432 update_block (dtrial
, thread
);
1433 new_rtx
= delete_from_delay_slot (dtrial
);
1434 if (thread
->deleted ())
1436 INSN_FROM_TARGET_P (next_to_match
) = 0;
1439 merged_insns
= gen_rtx_INSN_LIST (SImode
, dtrial
,
1442 if (++slot_number
== num_slots
)
1445 next_to_match
= XVECEXP (PATTERN (insn
), 0, slot_number
);
1449 /* Keep track of the set/referenced resources for the delay
1450 slots of any trial insns we encounter. */
1451 mark_set_resources (dtrial
, &set
, 0, MARK_SRC_DEST_CALL
);
1452 mark_referenced_resources (dtrial
, &needed
, true);
1457 /* If all insns in the delay slot have been matched and we were previously
1458 annulling the branch, we need not any more. In that case delete all the
1459 merged insns. Also clear the INSN_FROM_TARGET_P bit of each insn in
1460 the delay list so that we know that it isn't only being used at the
1462 if (slot_number
== num_slots
&& annul_p
)
1464 for (; merged_insns
; merged_insns
= merged_insns
->next ())
1466 if (GET_MODE (merged_insns
) == SImode
)
1470 update_block (merged_insns
->insn (), thread
);
1471 new_rtx
= delete_from_delay_slot (merged_insns
->insn ());
1472 if (thread
->deleted ())
1477 update_block (merged_insns
->insn (), thread
);
1478 delete_related_insns (merged_insns
->insn ());
1482 INSN_ANNULLED_BRANCH_P (delay_insn
) = 0;
1484 for (i
= 0; i
< XVECLEN (PATTERN (insn
), 0); i
++)
1485 INSN_FROM_TARGET_P (XVECEXP (PATTERN (insn
), 0, i
)) = 0;
1489 /* See if INSN is redundant with an insn in front of TARGET. Often this
1490 is called when INSN is a candidate for a delay slot of TARGET.
1491 DELAY_LIST are insns that will be placed in delay slots of TARGET in front
1492 of INSN. Often INSN will be redundant with an insn in a delay slot of
1493 some previous insn. This happens when we have a series of branches to the
1494 same label; in that case the first insn at the target might want to go
1495 into each of the delay slots.
1497 If we are not careful, this routine can take up a significant fraction
1498 of the total compilation time (4%), but only wins rarely. Hence we
1499 speed this routine up by making two passes. The first pass goes back
1500 until it hits a label and sees if it finds an insn with an identical
1501 pattern. Only in this (relatively rare) event does it check for
1504 We do not split insns we encounter. This could cause us not to find a
1505 redundant insn, but the cost of splitting seems greater than the possible
1506 gain in rare cases. */
1509 redundant_insn (rtx insn
, rtx_insn
*target
, rtx delay_list
)
1511 rtx target_main
= target
;
1512 rtx ipat
= PATTERN (insn
);
1515 struct resources needed
, set
;
1517 unsigned insns_to_search
;
1519 /* If INSN has any REG_UNUSED notes, it can't match anything since we
1520 are allowed to not actually assign to such a register. */
1521 if (find_reg_note (insn
, REG_UNUSED
, NULL_RTX
) != 0)
1524 /* Scan backwards looking for a match. */
1525 for (trial
= PREV_INSN (target
),
1526 insns_to_search
= MAX_DELAY_SLOT_INSN_SEARCH
;
1527 trial
&& insns_to_search
> 0;
1528 trial
= PREV_INSN (trial
))
1530 /* (use (insn))s can come immediately after a barrier if the
1531 label that used to precede them has been deleted as dead.
1532 See delete_related_insns. */
1533 if (LABEL_P (trial
) || BARRIER_P (trial
))
1536 if (!INSN_P (trial
))
1540 pat
= PATTERN (trial
);
1541 if (GET_CODE (pat
) == USE
|| GET_CODE (pat
) == CLOBBER
)
1544 if (rtx_sequence
*seq
= dyn_cast
<rtx_sequence
*> (pat
))
1546 /* Stop for a CALL and its delay slots because it is difficult to
1547 track its resource needs correctly. */
1548 if (CALL_P (seq
->element (0)))
1551 /* Stop for an INSN or JUMP_INSN with delayed effects and its delay
1552 slots because it is difficult to track its resource needs
1555 #ifdef INSN_SETS_ARE_DELAYED
1556 if (INSN_SETS_ARE_DELAYED (seq
->insn (0)))
1560 #ifdef INSN_REFERENCES_ARE_DELAYED
1561 if (INSN_REFERENCES_ARE_DELAYED (seq
->insn (0)))
1565 /* See if any of the insns in the delay slot match, updating
1566 resource requirements as we go. */
1567 for (i
= seq
->len () - 1; i
> 0; i
--)
1568 if (GET_CODE (seq
->element (i
)) == GET_CODE (insn
)
1569 && rtx_equal_p (PATTERN (seq
->element (i
)), ipat
)
1570 && ! find_reg_note (seq
->element (i
), REG_UNUSED
, NULL_RTX
))
1573 /* If found a match, exit this loop early. */
1578 else if (GET_CODE (trial
) == GET_CODE (insn
) && rtx_equal_p (pat
, ipat
)
1579 && ! find_reg_note (trial
, REG_UNUSED
, NULL_RTX
))
1583 /* If we didn't find an insn that matches, return 0. */
1587 /* See what resources this insn sets and needs. If they overlap, or
1588 if this insn references CC0, it can't be redundant. */
1590 CLEAR_RESOURCE (&needed
);
1591 CLEAR_RESOURCE (&set
);
1592 mark_set_resources (insn
, &set
, 0, MARK_SRC_DEST_CALL
);
1593 mark_referenced_resources (insn
, &needed
, true);
1595 /* If TARGET is a SEQUENCE, get the main insn. */
1596 if (NONJUMP_INSN_P (target
) && GET_CODE (PATTERN (target
)) == SEQUENCE
)
1597 target_main
= XVECEXP (PATTERN (target
), 0, 0);
1599 if (resource_conflicts_p (&needed
, &set
)
1601 || reg_mentioned_p (cc0_rtx
, ipat
)
1603 /* The insn requiring the delay may not set anything needed or set by
1605 || insn_sets_resource_p (target_main
, &needed
, true)
1606 || insn_sets_resource_p (target_main
, &set
, true))
1609 /* Insns we pass may not set either NEEDED or SET, so merge them for
1611 needed
.memory
|= set
.memory
;
1612 IOR_HARD_REG_SET (needed
.regs
, set
.regs
);
1614 /* This insn isn't redundant if it conflicts with an insn that either is
1615 or will be in a delay slot of TARGET. */
1619 if (insn_sets_resource_p (XEXP (delay_list
, 0), &needed
, true))
1621 delay_list
= XEXP (delay_list
, 1);
1624 if (NONJUMP_INSN_P (target
) && GET_CODE (PATTERN (target
)) == SEQUENCE
)
1625 for (i
= 1; i
< XVECLEN (PATTERN (target
), 0); i
++)
1626 if (insn_sets_resource_p (XVECEXP (PATTERN (target
), 0, i
), &needed
,
1630 /* Scan backwards until we reach a label or an insn that uses something
1631 INSN sets or sets something insn uses or sets. */
1633 for (trial
= PREV_INSN (target
),
1634 insns_to_search
= MAX_DELAY_SLOT_INSN_SEARCH
;
1635 trial
&& !LABEL_P (trial
) && insns_to_search
> 0;
1636 trial
= PREV_INSN (trial
))
1638 if (!INSN_P (trial
))
1642 pat
= PATTERN (trial
);
1643 if (GET_CODE (pat
) == USE
|| GET_CODE (pat
) == CLOBBER
)
1646 if (rtx_sequence
*seq
= dyn_cast
<rtx_sequence
*> (pat
))
1648 bool annul_p
= false;
1649 rtx_insn
*control
= seq
->insn (0);
1651 /* If this is a CALL_INSN and its delay slots, it is hard to track
1652 the resource needs properly, so give up. */
1653 if (CALL_P (control
))
1656 /* If this is an INSN or JUMP_INSN with delayed effects, it
1657 is hard to track the resource needs properly, so give up. */
1659 #ifdef INSN_SETS_ARE_DELAYED
1660 if (INSN_SETS_ARE_DELAYED (control
))
1664 #ifdef INSN_REFERENCES_ARE_DELAYED
1665 if (INSN_REFERENCES_ARE_DELAYED (control
))
1669 if (JUMP_P (control
))
1670 annul_p
= INSN_ANNULLED_BRANCH_P (control
);
1672 /* See if any of the insns in the delay slot match, updating
1673 resource requirements as we go. */
1674 for (i
= seq
->len () - 1; i
> 0; i
--)
1676 rtx candidate
= seq
->element (i
);
1678 /* If an insn will be annulled if the branch is false, it isn't
1679 considered as a possible duplicate insn. */
1680 if (rtx_equal_p (PATTERN (candidate
), ipat
)
1681 && ! (annul_p
&& INSN_FROM_TARGET_P (candidate
)))
1683 /* Show that this insn will be used in the sequel. */
1684 INSN_FROM_TARGET_P (candidate
) = 0;
1688 /* Unless this is an annulled insn from the target of a branch,
1689 we must stop if it sets anything needed or set by INSN. */
1690 if ((!annul_p
|| !INSN_FROM_TARGET_P (candidate
))
1691 && insn_sets_resource_p (candidate
, &needed
, true))
1695 /* If the insn requiring the delay slot conflicts with INSN, we
1697 if (insn_sets_resource_p (control
, &needed
, true))
1702 /* See if TRIAL is the same as INSN. */
1703 pat
= PATTERN (trial
);
1704 if (rtx_equal_p (pat
, ipat
))
1707 /* Can't go any further if TRIAL conflicts with INSN. */
1708 if (insn_sets_resource_p (trial
, &needed
, true))
1716 /* Return 1 if THREAD can only be executed in one way. If LABEL is nonzero,
1717 it is the target of the branch insn being scanned. If ALLOW_FALLTHROUGH
1718 is nonzero, we are allowed to fall into this thread; otherwise, we are
1721 If LABEL is used more than one or we pass a label other than LABEL before
1722 finding an active insn, we do not own this thread. */
1725 own_thread_p (rtx thread
, rtx label
, int allow_fallthrough
)
1727 rtx_insn
*active_insn
;
1730 /* We don't own the function end. */
1731 if (thread
== 0 || ANY_RETURN_P (thread
))
1734 /* We have a non-NULL insn. */
1735 rtx_insn
*thread_insn
= as_a
<rtx_insn
*> (thread
);
1737 /* Get the first active insn, or THREAD_INSN, if it is an active insn. */
1738 active_insn
= next_active_insn (PREV_INSN (thread_insn
));
1740 for (insn
= thread_insn
; insn
!= active_insn
; insn
= NEXT_INSN (insn
))
1742 && (insn
!= label
|| LABEL_NUSES (insn
) != 1))
1745 if (allow_fallthrough
)
1748 /* Ensure that we reach a BARRIER before any insn or label. */
1749 for (insn
= prev_nonnote_insn (thread_insn
);
1750 insn
== 0 || !BARRIER_P (insn
);
1751 insn
= prev_nonnote_insn (insn
))
1754 || (NONJUMP_INSN_P (insn
)
1755 && GET_CODE (PATTERN (insn
)) != USE
1756 && GET_CODE (PATTERN (insn
)) != CLOBBER
))
1762 /* Called when INSN is being moved from a location near the target of a jump.
1763 We leave a marker of the form (use (INSN)) immediately in front
1764 of WHERE for mark_target_live_regs. These markers will be deleted when
1767 We used to try to update the live status of registers if WHERE is at
1768 the start of a basic block, but that can't work since we may remove a
1769 BARRIER in relax_delay_slots. */
1772 update_block (rtx_insn
*insn
, rtx where
)
1774 /* Ignore if this was in a delay slot and it came from the target of
1776 if (INSN_FROM_TARGET_P (insn
))
1779 emit_insn_before (gen_rtx_USE (VOIDmode
, insn
), where
);
1781 /* INSN might be making a value live in a block where it didn't use to
1782 be. So recompute liveness information for this block. */
1784 incr_ticks_for_insn (insn
);
1787 /* Similar to REDIRECT_JUMP except that we update the BB_TICKS entry for
1788 the basic block containing the jump. */
1791 reorg_redirect_jump (rtx_insn
*jump
, rtx nlabel
)
1793 incr_ticks_for_insn (jump
);
1794 return redirect_jump (jump
, nlabel
, 1);
1797 /* Called when INSN is being moved forward into a delay slot of DELAYED_INSN.
1798 We check every instruction between INSN and DELAYED_INSN for REG_DEAD notes
1799 that reference values used in INSN. If we find one, then we move the
1800 REG_DEAD note to INSN.
1802 This is needed to handle the case where a later insn (after INSN) has a
1803 REG_DEAD note for a register used by INSN, and this later insn subsequently
1804 gets moved before a CODE_LABEL because it is a redundant insn. In this
1805 case, mark_target_live_regs may be confused into thinking the register
1806 is dead because it sees a REG_DEAD note immediately before a CODE_LABEL. */
1809 update_reg_dead_notes (rtx insn
, rtx delayed_insn
)
1813 for (p
= next_nonnote_insn (insn
); p
!= delayed_insn
;
1814 p
= next_nonnote_insn (p
))
1815 for (link
= REG_NOTES (p
); link
; link
= next
)
1817 next
= XEXP (link
, 1);
1819 if (REG_NOTE_KIND (link
) != REG_DEAD
1820 || !REG_P (XEXP (link
, 0)))
1823 if (reg_referenced_p (XEXP (link
, 0), PATTERN (insn
)))
1825 /* Move the REG_DEAD note from P to INSN. */
1826 remove_note (p
, link
);
1827 XEXP (link
, 1) = REG_NOTES (insn
);
1828 REG_NOTES (insn
) = link
;
1833 /* Called when an insn redundant with start_insn is deleted. If there
1834 is a REG_DEAD note for the target of start_insn between start_insn
1835 and stop_insn, then the REG_DEAD note needs to be deleted since the
1836 value no longer dies there.
1838 If the REG_DEAD note isn't deleted, then mark_target_live_regs may be
1839 confused into thinking the register is dead. */
1842 fix_reg_dead_note (rtx start_insn
, rtx stop_insn
)
1846 for (p
= next_nonnote_insn (start_insn
); p
!= stop_insn
;
1847 p
= next_nonnote_insn (p
))
1848 for (link
= REG_NOTES (p
); link
; link
= next
)
1850 next
= XEXP (link
, 1);
1852 if (REG_NOTE_KIND (link
) != REG_DEAD
1853 || !REG_P (XEXP (link
, 0)))
1856 if (reg_set_p (XEXP (link
, 0), PATTERN (start_insn
)))
1858 remove_note (p
, link
);
1864 /* Delete any REG_UNUSED notes that exist on INSN but not on REDUNDANT_INSN.
1866 This handles the case of udivmodXi4 instructions which optimize their
1867 output depending on whether any REG_UNUSED notes are present.
1868 we must make sure that INSN calculates as many results as REDUNDANT_INSN
1872 update_reg_unused_notes (rtx insn
, rtx redundant_insn
)
1876 for (link
= REG_NOTES (insn
); link
; link
= next
)
1878 next
= XEXP (link
, 1);
1880 if (REG_NOTE_KIND (link
) != REG_UNUSED
1881 || !REG_P (XEXP (link
, 0)))
1884 if (! find_regno_note (redundant_insn
, REG_UNUSED
,
1885 REGNO (XEXP (link
, 0))))
1886 remove_note (insn
, link
);
1890 static vec
<rtx
> sibling_labels
;
1892 /* Return the label before INSN, or put a new label there. If SIBLING is
1893 non-zero, it is another label associated with the new label (if any),
1894 typically the former target of the jump that will be redirected to
1898 get_label_before (rtx_insn
*insn
, rtx sibling
)
1902 /* Find an existing label at this point
1903 or make a new one if there is none. */
1904 label
= prev_nonnote_insn (insn
);
1906 if (label
== 0 || !LABEL_P (label
))
1908 rtx_insn
*prev
= PREV_INSN (insn
);
1910 label
= gen_label_rtx ();
1911 emit_label_after (label
, prev
);
1912 LABEL_NUSES (label
) = 0;
1915 sibling_labels
.safe_push (label
);
1916 sibling_labels
.safe_push (sibling
);
1922 /* Scan a function looking for insns that need a delay slot and find insns to
1923 put into the delay slot.
1925 NON_JUMPS_P is nonzero if we are to only try to fill non-jump insns (such
1926 as calls). We do these first since we don't want jump insns (that are
1927 easier to fill) to get the only insns that could be used for non-jump insns.
1928 When it is zero, only try to fill JUMP_INSNs.
1930 When slots are filled in this manner, the insns (including the
1931 delay_insn) are put together in a SEQUENCE rtx. In this fashion,
1932 it is possible to tell whether a delay slot has really been filled
1933 or not. `final' knows how to deal with this, by communicating
1934 through FINAL_SEQUENCE. */
1937 fill_simple_delay_slots (int non_jumps_p
)
1939 rtx_insn
*insn
, *trial
, *next_trial
;
1942 int num_unfilled_slots
= unfilled_slots_next
- unfilled_slots_base
;
1943 struct resources needed
, set
;
1944 int slots_to_fill
, slots_filled
;
1945 rtx_insn_list
*delay_list
;
1947 for (i
= 0; i
< num_unfilled_slots
; i
++)
1950 /* Get the next insn to fill. If it has already had any slots assigned,
1951 we can't do anything with it. Maybe we'll improve this later. */
1953 insn
= unfilled_slots_base
[i
];
1956 || (NONJUMP_INSN_P (insn
)
1957 && GET_CODE (PATTERN (insn
)) == SEQUENCE
)
1958 || (JUMP_P (insn
) && non_jumps_p
)
1959 || (!JUMP_P (insn
) && ! non_jumps_p
))
1962 /* It may have been that this insn used to need delay slots, but
1963 now doesn't; ignore in that case. This can happen, for example,
1964 on the HP PA RISC, where the number of delay slots depends on
1965 what insns are nearby. */
1966 slots_to_fill
= num_delay_slots (insn
);
1968 /* Some machine description have defined instructions to have
1969 delay slots only in certain circumstances which may depend on
1970 nearby insns (which change due to reorg's actions).
1972 For example, the PA port normally has delay slots for unconditional
1975 However, the PA port claims such jumps do not have a delay slot
1976 if they are immediate successors of certain CALL_INSNs. This
1977 allows the port to favor filling the delay slot of the call with
1978 the unconditional jump. */
1979 if (slots_to_fill
== 0)
1982 /* This insn needs, or can use, some delay slots. SLOTS_TO_FILL
1983 says how many. After initialization, first try optimizing
1986 nop add %o7,.-L1,%o7
1990 If this case applies, the delay slot of the call is filled with
1991 the unconditional jump. This is done first to avoid having the
1992 delay slot of the call filled in the backward scan. Also, since
1993 the unconditional jump is likely to also have a delay slot, that
1994 insn must exist when it is subsequently scanned.
1996 This is tried on each insn with delay slots as some machines
1997 have insns which perform calls, but are not represented as
2004 flags
= get_jump_flags (insn
, JUMP_LABEL (insn
));
2006 flags
= get_jump_flags (insn
, NULL_RTX
);
2008 if ((trial
= next_active_insn (insn
))
2010 && simplejump_p (trial
)
2011 && eligible_for_delay (insn
, slots_filled
, trial
, flags
)
2012 && no_labels_between_p (insn
, trial
)
2013 && ! can_throw_internal (trial
))
2017 delay_list
= add_to_delay_list (trial
, delay_list
);
2019 /* TRIAL may have had its delay slot filled, then unfilled. When
2020 the delay slot is unfilled, TRIAL is placed back on the unfilled
2021 slots obstack. Unfortunately, it is placed on the end of the
2022 obstack, not in its original location. Therefore, we must search
2023 from entry i + 1 to the end of the unfilled slots obstack to
2024 try and find TRIAL. */
2025 tmp
= &unfilled_slots_base
[i
+ 1];
2026 while (*tmp
!= trial
&& tmp
!= unfilled_slots_next
)
2029 /* Remove the unconditional jump from consideration for delay slot
2030 filling and unthread it. */
2034 rtx_insn
*next
= NEXT_INSN (trial
);
2035 rtx_insn
*prev
= PREV_INSN (trial
);
2037 SET_NEXT_INSN (prev
) = next
;
2039 SET_PREV_INSN (next
) = prev
;
2043 /* Now, scan backwards from the insn to search for a potential
2044 delay-slot candidate. Stop searching when a label or jump is hit.
2046 For each candidate, if it is to go into the delay slot (moved
2047 forward in execution sequence), it must not need or set any resources
2048 that were set by later insns and must not set any resources that
2049 are needed for those insns.
2051 The delay slot insn itself sets resources unless it is a call
2052 (in which case the called routine, not the insn itself, is doing
2055 if (slots_filled
< slots_to_fill
)
2057 CLEAR_RESOURCE (&needed
);
2058 CLEAR_RESOURCE (&set
);
2059 mark_set_resources (insn
, &set
, 0, MARK_SRC_DEST
);
2060 mark_referenced_resources (insn
, &needed
, false);
2062 for (trial
= prev_nonnote_insn (insn
); ! stop_search_p (trial
, 1);
2065 next_trial
= prev_nonnote_insn (trial
);
2067 /* This must be an INSN or CALL_INSN. */
2068 pat
= PATTERN (trial
);
2070 /* Stand-alone USE and CLOBBER are just for flow. */
2071 if (GET_CODE (pat
) == USE
|| GET_CODE (pat
) == CLOBBER
)
2074 /* Check for resource conflict first, to avoid unnecessary
2076 if (! insn_references_resource_p (trial
, &set
, true)
2077 && ! insn_sets_resource_p (trial
, &set
, true)
2078 && ! insn_sets_resource_p (trial
, &needed
, true)
2080 /* Can't separate set of cc0 from its use. */
2081 && ! (reg_mentioned_p (cc0_rtx
, pat
) && ! sets_cc0_p (pat
))
2083 && ! can_throw_internal (trial
))
2085 trial
= try_split (pat
, trial
, 1);
2086 next_trial
= prev_nonnote_insn (trial
);
2087 if (eligible_for_delay (insn
, slots_filled
, trial
, flags
))
2089 /* In this case, we are searching backward, so if we
2090 find insns to put on the delay list, we want
2091 to put them at the head, rather than the
2092 tail, of the list. */
2094 update_reg_dead_notes (trial
, insn
);
2095 delay_list
= gen_rtx_INSN_LIST (VOIDmode
,
2097 update_block (trial
, trial
);
2098 delete_related_insns (trial
);
2099 if (slots_to_fill
== ++slots_filled
)
2105 mark_set_resources (trial
, &set
, 0, MARK_SRC_DEST_CALL
);
2106 mark_referenced_resources (trial
, &needed
, true);
2110 /* If all needed slots haven't been filled, we come here. */
2112 /* Try to optimize case of jumping around a single insn. */
2113 #if defined(ANNUL_IFFALSE_SLOTS) || defined(ANNUL_IFTRUE_SLOTS)
2114 if (slots_filled
!= slots_to_fill
2117 && (condjump_p (insn
) || condjump_in_parallel_p (insn
))
2118 && !ANY_RETURN_P (JUMP_LABEL (insn
)))
2120 delay_list
= optimize_skip (insn
);
2126 /* Try to get insns from beyond the insn needing the delay slot.
2127 These insns can neither set or reference resources set in insns being
2128 skipped, cannot set resources in the insn being skipped, and, if this
2129 is a CALL_INSN (or a CALL_INSN is passed), cannot trap (because the
2130 call might not return).
2132 There used to be code which continued past the target label if
2133 we saw all uses of the target label. This code did not work,
2134 because it failed to account for some instructions which were
2135 both annulled and marked as from the target. This can happen as a
2136 result of optimize_skip. Since this code was redundant with
2137 fill_eager_delay_slots anyways, it was just deleted. */
2139 if (slots_filled
!= slots_to_fill
2140 /* If this instruction could throw an exception which is
2141 caught in the same function, then it's not safe to fill
2142 the delay slot with an instruction from beyond this
2143 point. For example, consider:
2154 Even though `i' is a local variable, we must be sure not
2155 to put `i = 3' in the delay slot if `f' might throw an
2158 Presumably, we should also check to see if we could get
2159 back to this function via `setjmp'. */
2160 && ! can_throw_internal (insn
)
2163 int maybe_never
= 0;
2164 rtx pat
, trial_delay
;
2166 CLEAR_RESOURCE (&needed
);
2167 CLEAR_RESOURCE (&set
);
2168 mark_set_resources (insn
, &set
, 0, MARK_SRC_DEST_CALL
);
2169 mark_referenced_resources (insn
, &needed
, true);
2174 for (trial
= next_nonnote_insn (insn
); !stop_search_p (trial
, 1);
2177 next_trial
= next_nonnote_insn (trial
);
2179 /* This must be an INSN or CALL_INSN. */
2180 pat
= PATTERN (trial
);
2182 /* Stand-alone USE and CLOBBER are just for flow. */
2183 if (GET_CODE (pat
) == USE
|| GET_CODE (pat
) == CLOBBER
)
2186 /* If this already has filled delay slots, get the insn needing
2188 if (GET_CODE (pat
) == SEQUENCE
)
2189 trial_delay
= XVECEXP (pat
, 0, 0);
2191 trial_delay
= trial
;
2193 /* Stop our search when seeing a jump. */
2194 if (JUMP_P (trial_delay
))
2197 /* See if we have a resource problem before we try to split. */
2198 if (GET_CODE (pat
) != SEQUENCE
2199 && ! insn_references_resource_p (trial
, &set
, true)
2200 && ! insn_sets_resource_p (trial
, &set
, true)
2201 && ! insn_sets_resource_p (trial
, &needed
, true)
2203 && ! (reg_mentioned_p (cc0_rtx
, pat
) && ! sets_cc0_p (pat
))
2205 && ! (maybe_never
&& may_trap_or_fault_p (pat
))
2206 && (trial
= try_split (pat
, trial
, 0))
2207 && eligible_for_delay (insn
, slots_filled
, trial
, flags
)
2208 && ! can_throw_internal (trial
))
2210 next_trial
= next_nonnote_insn (trial
);
2211 delay_list
= add_to_delay_list (trial
, delay_list
);
2213 if (reg_mentioned_p (cc0_rtx
, pat
))
2214 link_cc0_insns (trial
);
2216 delete_related_insns (trial
);
2217 if (slots_to_fill
== ++slots_filled
)
2222 mark_set_resources (trial
, &set
, 0, MARK_SRC_DEST_CALL
);
2223 mark_referenced_resources (trial
, &needed
, true);
2225 /* Ensure we don't put insns between the setting of cc and the
2226 comparison by moving a setting of cc into an earlier delay
2227 slot since these insns could clobber the condition code. */
2230 /* If this is a call, we might not get here. */
2231 if (CALL_P (trial_delay
))
2235 /* If there are slots left to fill and our search was stopped by an
2236 unconditional branch, try the insn at the branch target. We can
2237 redirect the branch if it works.
2239 Don't do this if the insn at the branch target is a branch. */
2240 if (slots_to_fill
!= slots_filled
2242 && jump_to_label_p (trial
)
2243 && simplejump_p (trial
)
2244 && (next_trial
= next_active_insn (JUMP_LABEL (trial
))) != 0
2245 && ! (NONJUMP_INSN_P (next_trial
)
2246 && GET_CODE (PATTERN (next_trial
)) == SEQUENCE
)
2247 && !JUMP_P (next_trial
)
2248 && ! insn_references_resource_p (next_trial
, &set
, true)
2249 && ! insn_sets_resource_p (next_trial
, &set
, true)
2250 && ! insn_sets_resource_p (next_trial
, &needed
, true)
2252 && ! reg_mentioned_p (cc0_rtx
, PATTERN (next_trial
))
2254 && ! (maybe_never
&& may_trap_or_fault_p (PATTERN (next_trial
)))
2255 && (next_trial
= try_split (PATTERN (next_trial
), next_trial
, 0))
2256 && eligible_for_delay (insn
, slots_filled
, next_trial
, flags
)
2257 && ! can_throw_internal (trial
))
2259 /* See comment in relax_delay_slots about necessity of using
2260 next_real_insn here. */
2261 rtx_insn
*new_label
= next_real_insn (next_trial
);
2264 new_label
= get_label_before (new_label
, JUMP_LABEL (trial
));
2266 new_label
= find_end_label (simple_return_rtx
);
2271 = add_to_delay_list (copy_delay_slot_insn (next_trial
),
2274 reorg_redirect_jump (trial
, new_label
);
2279 /* If this is an unconditional jump, then try to get insns from the
2280 target of the jump. */
2282 && simplejump_p (insn
)
2283 && slots_filled
!= slots_to_fill
)
2285 = fill_slots_from_thread (insn
, const_true_rtx
,
2286 next_active_insn (JUMP_LABEL (insn
)),
2288 own_thread_p (JUMP_LABEL (insn
),
2289 JUMP_LABEL (insn
), 0),
2290 slots_to_fill
, &slots_filled
,
2294 unfilled_slots_base
[i
]
2295 = emit_delay_sequence (insn
, delay_list
, slots_filled
);
2297 if (slots_to_fill
== slots_filled
)
2298 unfilled_slots_base
[i
] = 0;
2300 note_delay_statistics (slots_filled
, 0);
2304 /* Follow any unconditional jump at LABEL, for the purpose of redirecting JUMP;
2305 return the ultimate label reached by any such chain of jumps.
2306 Return a suitable return rtx if the chain ultimately leads to a
2308 If LABEL is not followed by a jump, return LABEL.
2309 If the chain loops or we can't find end, return LABEL,
2310 since that tells caller to avoid changing the insn.
2311 If the returned label is obtained by following a crossing jump,
2312 set *CROSSING to true, otherwise set it to false. */
2315 follow_jumps (rtx label
, rtx_insn
*jump
, bool *crossing
)
2322 if (ANY_RETURN_P (label
))
2325 rtx_insn
*value
= as_a
<rtx_insn
*> (label
);
2329 && (insn
= next_active_insn (value
)) != 0
2331 && JUMP_LABEL (insn
) != NULL_RTX
2332 && ((any_uncondjump_p (insn
) && onlyjump_p (insn
))
2333 || ANY_RETURN_P (PATTERN (insn
)))
2334 && (next
= NEXT_INSN (insn
))
2335 && BARRIER_P (next
));
2338 rtx this_label_or_return
= JUMP_LABEL (insn
);
2340 /* If we have found a cycle, make the insn jump to itself. */
2341 if (this_label_or_return
== label
)
2344 /* Cannot follow returns and cannot look through tablejumps. */
2345 if (ANY_RETURN_P (this_label_or_return
))
2346 return this_label_or_return
;
2348 rtx_insn
*this_label
= as_a
<rtx_insn
*> (this_label_or_return
);
2349 if (NEXT_INSN (this_label
)
2350 && JUMP_TABLE_DATA_P (NEXT_INSN (this_label
)))
2353 if (!targetm
.can_follow_jump (jump
, insn
))
2356 *crossing
= CROSSING_JUMP_P (jump
);
2364 /* Try to find insns to place in delay slots.
2366 INSN is the jump needing SLOTS_TO_FILL delay slots. It tests CONDITION
2367 or is an unconditional branch if CONDITION is const_true_rtx.
2368 *PSLOTS_FILLED is updated with the number of slots that we have filled.
2370 THREAD is a flow-of-control, either the insns to be executed if the
2371 branch is true or if the branch is false, THREAD_IF_TRUE says which.
2373 OPPOSITE_THREAD is the thread in the opposite direction. It is used
2374 to see if any potential delay slot insns set things needed there.
2376 LIKELY is nonzero if it is extremely likely that the branch will be
2377 taken and THREAD_IF_TRUE is set. This is used for the branch at the
2378 end of a loop back up to the top.
2380 OWN_THREAD and OWN_OPPOSITE_THREAD are true if we are the only user of the
2381 thread. I.e., it is the fallthrough code of our jump or the target of the
2382 jump when we are the only jump going there.
2384 If OWN_THREAD is false, it must be the "true" thread of a jump. In that
2385 case, we can only take insns from the head of the thread for our delay
2386 slot. We then adjust the jump to point after the insns we have taken. */
2388 static rtx_insn_list
*
2389 fill_slots_from_thread (rtx_insn
*insn
, rtx condition
, rtx thread_or_return
,
2390 rtx opposite_thread
, int likely
,
2392 int own_thread
, int slots_to_fill
,
2393 int *pslots_filled
, rtx_insn_list
*delay_list
)
2396 struct resources opposite_needed
, set
, needed
;
2402 /* Validate our arguments. */
2403 gcc_assert (condition
!= const_true_rtx
|| thread_if_true
);
2404 gcc_assert (own_thread
|| thread_if_true
);
2406 flags
= get_jump_flags (insn
, JUMP_LABEL (insn
));
2408 /* If our thread is the end of subroutine, we can't get any delay
2410 if (thread_or_return
== NULL_RTX
|| ANY_RETURN_P (thread_or_return
))
2413 rtx_insn
*thread
= as_a
<rtx_insn
*> (thread_or_return
);
2415 /* If this is an unconditional branch, nothing is needed at the
2416 opposite thread. Otherwise, compute what is needed there. */
2417 if (condition
== const_true_rtx
)
2418 CLEAR_RESOURCE (&opposite_needed
);
2420 mark_target_live_regs (get_insns (), opposite_thread
, &opposite_needed
);
2422 /* If the insn at THREAD can be split, do it here to avoid having to
2423 update THREAD and NEW_THREAD if it is done in the loop below. Also
2424 initialize NEW_THREAD. */
2426 new_thread
= thread
= try_split (PATTERN (thread
), thread
, 0);
2428 /* Scan insns at THREAD. We are looking for an insn that can be removed
2429 from THREAD (it neither sets nor references resources that were set
2430 ahead of it and it doesn't set anything needs by the insns ahead of
2431 it) and that either can be placed in an annulling insn or aren't
2432 needed at OPPOSITE_THREAD. */
2434 CLEAR_RESOURCE (&needed
);
2435 CLEAR_RESOURCE (&set
);
2437 /* If we do not own this thread, we must stop as soon as we find
2438 something that we can't put in a delay slot, since all we can do
2439 is branch into THREAD at a later point. Therefore, labels stop
2440 the search if this is not the `true' thread. */
2442 for (trial
= thread
;
2443 ! stop_search_p (trial
, ! thread_if_true
) && (! lose
|| own_thread
);
2444 trial
= next_nonnote_insn (trial
))
2448 /* If we have passed a label, we no longer own this thread. */
2449 if (LABEL_P (trial
))
2455 pat
= PATTERN (trial
);
2456 if (GET_CODE (pat
) == USE
|| GET_CODE (pat
) == CLOBBER
)
2459 /* If TRIAL conflicts with the insns ahead of it, we lose. Also,
2460 don't separate or copy insns that set and use CC0. */
2461 if (! insn_references_resource_p (trial
, &set
, true)
2462 && ! insn_sets_resource_p (trial
, &set
, true)
2463 && ! insn_sets_resource_p (trial
, &needed
, true)
2465 && ! (reg_mentioned_p (cc0_rtx
, pat
)
2466 && (! own_thread
|| ! sets_cc0_p (pat
)))
2468 && ! can_throw_internal (trial
))
2472 /* If TRIAL is redundant with some insn before INSN, we don't
2473 actually need to add it to the delay list; we can merely pretend
2475 if ((prior_insn
= redundant_insn (trial
, insn
, delay_list
)))
2477 fix_reg_dead_note (prior_insn
, insn
);
2480 update_block (trial
, thread
);
2481 if (trial
== thread
)
2483 thread
= next_active_insn (thread
);
2484 if (new_thread
== trial
)
2485 new_thread
= thread
;
2488 delete_related_insns (trial
);
2492 update_reg_unused_notes (prior_insn
, trial
);
2493 new_thread
= next_active_insn (trial
);
2499 /* There are two ways we can win: If TRIAL doesn't set anything
2500 needed at the opposite thread and can't trap, or if it can
2501 go into an annulled delay slot. */
2503 && (condition
== const_true_rtx
2504 || (! insn_sets_resource_p (trial
, &opposite_needed
, true)
2505 && ! may_trap_or_fault_p (pat
)
2506 && ! RTX_FRAME_RELATED_P (trial
))))
2509 trial
= try_split (pat
, trial
, 0);
2510 if (new_thread
== old_trial
)
2512 if (thread
== old_trial
)
2514 pat
= PATTERN (trial
);
2515 if (eligible_for_delay (insn
, *pslots_filled
, trial
, flags
))
2519 #ifdef ANNUL_IFTRUE_SLOTS
2522 #ifdef ANNUL_IFFALSE_SLOTS
2528 trial
= try_split (pat
, trial
, 0);
2529 if (new_thread
== old_trial
)
2531 if (thread
== old_trial
)
2533 pat
= PATTERN (trial
);
2534 if ((must_annul
|| delay_list
== NULL
) && (thread_if_true
2535 ? check_annul_list_true_false (0, delay_list
)
2536 && eligible_for_annul_false (insn
, *pslots_filled
, trial
, flags
)
2537 : check_annul_list_true_false (1, delay_list
)
2538 && eligible_for_annul_true (insn
, *pslots_filled
, trial
, flags
)))
2546 if (reg_mentioned_p (cc0_rtx
, pat
))
2547 link_cc0_insns (trial
);
2550 /* If we own this thread, delete the insn. If this is the
2551 destination of a branch, show that a basic block status
2552 may have been updated. In any case, mark the new
2553 starting point of this thread. */
2558 update_block (trial
, thread
);
2559 if (trial
== thread
)
2561 thread
= next_active_insn (thread
);
2562 if (new_thread
== trial
)
2563 new_thread
= thread
;
2566 /* We are moving this insn, not deleting it. We must
2567 temporarily increment the use count on any referenced
2568 label lest it be deleted by delete_related_insns. */
2569 for (note
= REG_NOTES (trial
);
2571 note
= XEXP (note
, 1))
2572 if (REG_NOTE_KIND (note
) == REG_LABEL_OPERAND
2573 || REG_NOTE_KIND (note
) == REG_LABEL_TARGET
)
2575 /* REG_LABEL_OPERAND could be
2576 NOTE_INSN_DELETED_LABEL too. */
2577 if (LABEL_P (XEXP (note
, 0)))
2578 LABEL_NUSES (XEXP (note
, 0))++;
2580 gcc_assert (REG_NOTE_KIND (note
)
2581 == REG_LABEL_OPERAND
);
2583 if (jump_to_label_p (trial
))
2584 LABEL_NUSES (JUMP_LABEL (trial
))++;
2586 delete_related_insns (trial
);
2588 for (note
= REG_NOTES (trial
);
2590 note
= XEXP (note
, 1))
2591 if (REG_NOTE_KIND (note
) == REG_LABEL_OPERAND
2592 || REG_NOTE_KIND (note
) == REG_LABEL_TARGET
)
2594 /* REG_LABEL_OPERAND could be
2595 NOTE_INSN_DELETED_LABEL too. */
2596 if (LABEL_P (XEXP (note
, 0)))
2597 LABEL_NUSES (XEXP (note
, 0))--;
2599 gcc_assert (REG_NOTE_KIND (note
)
2600 == REG_LABEL_OPERAND
);
2602 if (jump_to_label_p (trial
))
2603 LABEL_NUSES (JUMP_LABEL (trial
))--;
2606 new_thread
= next_active_insn (trial
);
2608 temp
= own_thread
? trial
: copy_delay_slot_insn (trial
);
2610 INSN_FROM_TARGET_P (temp
) = 1;
2612 delay_list
= add_to_delay_list (temp
, delay_list
);
2614 if (slots_to_fill
== ++(*pslots_filled
))
2616 /* Even though we have filled all the slots, we
2617 may be branching to a location that has a
2618 redundant insn. Skip any if so. */
2619 while (new_thread
&& ! own_thread
2620 && ! insn_sets_resource_p (new_thread
, &set
, true)
2621 && ! insn_sets_resource_p (new_thread
, &needed
,
2623 && ! insn_references_resource_p (new_thread
,
2626 = redundant_insn (new_thread
, insn
,
2629 /* We know we do not own the thread, so no need
2630 to call update_block and delete_insn. */
2631 fix_reg_dead_note (prior_insn
, insn
);
2632 update_reg_unused_notes (prior_insn
, new_thread
);
2633 new_thread
= next_active_insn (new_thread
);
2643 /* This insn can't go into a delay slot. */
2645 mark_set_resources (trial
, &set
, 0, MARK_SRC_DEST_CALL
);
2646 mark_referenced_resources (trial
, &needed
, true);
2648 /* Ensure we don't put insns between the setting of cc and the comparison
2649 by moving a setting of cc into an earlier delay slot since these insns
2650 could clobber the condition code. */
2653 /* If this insn is a register-register copy and the next insn has
2654 a use of our destination, change it to use our source. That way,
2655 it will become a candidate for our delay slot the next time
2656 through this loop. This case occurs commonly in loops that
2659 We could check for more complex cases than those tested below,
2660 but it doesn't seem worth it. It might also be a good idea to try
2661 to swap the two insns. That might do better.
2663 We can't do this if the next insn modifies our destination, because
2664 that would make the replacement into the insn invalid. We also can't
2665 do this if it modifies our source, because it might be an earlyclobber
2666 operand. This latter test also prevents updating the contents of
2667 a PRE_INC. We also can't do this if there's overlap of source and
2668 destination. Overlap may happen for larger-than-register-size modes. */
2670 if (NONJUMP_INSN_P (trial
) && GET_CODE (pat
) == SET
2671 && REG_P (SET_SRC (pat
))
2672 && REG_P (SET_DEST (pat
))
2673 && !reg_overlap_mentioned_p (SET_DEST (pat
), SET_SRC (pat
)))
2675 rtx next
= next_nonnote_insn (trial
);
2677 if (next
&& NONJUMP_INSN_P (next
)
2678 && GET_CODE (PATTERN (next
)) != USE
2679 && ! reg_set_p (SET_DEST (pat
), next
)
2680 && ! reg_set_p (SET_SRC (pat
), next
)
2681 && reg_referenced_p (SET_DEST (pat
), PATTERN (next
))
2682 && ! modified_in_p (SET_DEST (pat
), next
))
2683 validate_replace_rtx (SET_DEST (pat
), SET_SRC (pat
), next
);
2687 /* If we stopped on a branch insn that has delay slots, see if we can
2688 steal some of the insns in those slots. */
2689 if (trial
&& NONJUMP_INSN_P (trial
)
2690 && GET_CODE (PATTERN (trial
)) == SEQUENCE
2691 && JUMP_P (XVECEXP (PATTERN (trial
), 0, 0)))
2693 rtx_sequence
*sequence
= as_a
<rtx_sequence
*> (PATTERN (trial
));
2694 /* If this is the `true' thread, we will want to follow the jump,
2695 so we can only do this if we have taken everything up to here. */
2696 if (thread_if_true
&& trial
== new_thread
)
2699 = steal_delay_list_from_target (insn
, condition
, sequence
,
2700 delay_list
, &set
, &needed
,
2701 &opposite_needed
, slots_to_fill
,
2702 pslots_filled
, &must_annul
,
2704 /* If we owned the thread and are told that it branched
2705 elsewhere, make sure we own the thread at the new location. */
2706 if (own_thread
&& trial
!= new_thread
)
2707 own_thread
= own_thread_p (new_thread
, new_thread
, 0);
2709 else if (! thread_if_true
)
2711 = steal_delay_list_from_fallthrough (insn
, condition
,
2713 delay_list
, &set
, &needed
,
2714 &opposite_needed
, slots_to_fill
,
2715 pslots_filled
, &must_annul
);
2718 /* If we haven't found anything for this delay slot and it is very
2719 likely that the branch will be taken, see if the insn at our target
2720 increments or decrements a register with an increment that does not
2721 depend on the destination register. If so, try to place the opposite
2722 arithmetic insn after the jump insn and put the arithmetic insn in the
2723 delay slot. If we can't do this, return. */
2724 if (delay_list
== 0 && likely
2725 && new_thread
&& !ANY_RETURN_P (new_thread
)
2726 && NONJUMP_INSN_P (new_thread
)
2727 && !RTX_FRAME_RELATED_P (new_thread
)
2728 && GET_CODE (PATTERN (new_thread
)) != ASM_INPUT
2729 && asm_noperands (PATTERN (new_thread
)) < 0)
2731 rtx pat
= PATTERN (new_thread
);
2735 /* We know "new_thread" is an insn due to NONJUMP_INSN_P (new_thread)
2737 trial
= as_a
<rtx_insn
*> (new_thread
);
2738 pat
= PATTERN (trial
);
2740 if (!NONJUMP_INSN_P (trial
)
2741 || GET_CODE (pat
) != SET
2742 || ! eligible_for_delay (insn
, 0, trial
, flags
)
2743 || can_throw_internal (trial
))
2746 dest
= SET_DEST (pat
), src
= SET_SRC (pat
);
2747 if ((GET_CODE (src
) == PLUS
|| GET_CODE (src
) == MINUS
)
2748 && rtx_equal_p (XEXP (src
, 0), dest
)
2749 && (!FLOAT_MODE_P (GET_MODE (src
))
2750 || flag_unsafe_math_optimizations
)
2751 && ! reg_overlap_mentioned_p (dest
, XEXP (src
, 1))
2752 && ! side_effects_p (pat
))
2754 rtx other
= XEXP (src
, 1);
2758 /* If this is a constant adjustment, use the same code with
2759 the negated constant. Otherwise, reverse the sense of the
2761 if (CONST_INT_P (other
))
2762 new_arith
= gen_rtx_fmt_ee (GET_CODE (src
), GET_MODE (src
), dest
,
2763 negate_rtx (GET_MODE (src
), other
));
2765 new_arith
= gen_rtx_fmt_ee (GET_CODE (src
) == PLUS
? MINUS
: PLUS
,
2766 GET_MODE (src
), dest
, other
);
2768 ninsn
= emit_insn_after (gen_rtx_SET (VOIDmode
, dest
, new_arith
),
2771 if (recog_memoized (ninsn
) < 0
2772 || (extract_insn (ninsn
), ! constrain_operands (1)))
2774 delete_related_insns (ninsn
);
2780 update_block (trial
, thread
);
2781 if (trial
== thread
)
2783 thread
= next_active_insn (thread
);
2784 if (new_thread
== trial
)
2785 new_thread
= thread
;
2787 delete_related_insns (trial
);
2790 new_thread
= next_active_insn (trial
);
2792 ninsn
= own_thread
? trial
: copy_delay_slot_insn (trial
);
2794 INSN_FROM_TARGET_P (ninsn
) = 1;
2796 delay_list
= add_to_delay_list (ninsn
, NULL
);
2801 if (delay_list
&& must_annul
)
2802 INSN_ANNULLED_BRANCH_P (insn
) = 1;
2804 /* If we are to branch into the middle of this thread, find an appropriate
2805 label or make a new one if none, and redirect INSN to it. If we hit the
2806 end of the function, use the end-of-function label. */
2807 if (new_thread
!= thread
)
2810 bool crossing
= false;
2812 gcc_assert (thread_if_true
);
2814 if (new_thread
&& simplejump_or_return_p (new_thread
)
2815 && redirect_with_delay_list_safe_p (insn
,
2816 JUMP_LABEL (new_thread
),
2818 new_thread
= follow_jumps (JUMP_LABEL (new_thread
), insn
,
2821 if (ANY_RETURN_P (new_thread
))
2822 label
= find_end_label (new_thread
);
2823 else if (LABEL_P (new_thread
))
2826 label
= get_label_before (as_a
<rtx_insn
*> (new_thread
),
2831 reorg_redirect_jump (insn
, label
);
2833 CROSSING_JUMP_P (insn
) = 1;
2840 /* Make another attempt to find insns to place in delay slots.
2842 We previously looked for insns located in front of the delay insn
2843 and, for non-jump delay insns, located behind the delay insn.
2845 Here only try to schedule jump insns and try to move insns from either
2846 the target or the following insns into the delay slot. If annulling is
2847 supported, we will be likely to do this. Otherwise, we can do this only
2851 fill_eager_delay_slots (void)
2855 int num_unfilled_slots
= unfilled_slots_next
- unfilled_slots_base
;
2857 for (i
= 0; i
< num_unfilled_slots
; i
++)
2860 rtx target_label
, insn_at_target
;
2861 rtx_insn
*fallthrough_insn
;
2862 rtx_insn_list
*delay_list
= 0;
2864 int own_fallthrough
;
2865 int prediction
, slots_to_fill
, slots_filled
;
2867 insn
= unfilled_slots_base
[i
];
2871 || ! (condjump_p (insn
) || condjump_in_parallel_p (insn
)))
2874 slots_to_fill
= num_delay_slots (insn
);
2875 /* Some machine description have defined instructions to have
2876 delay slots only in certain circumstances which may depend on
2877 nearby insns (which change due to reorg's actions).
2879 For example, the PA port normally has delay slots for unconditional
2882 However, the PA port claims such jumps do not have a delay slot
2883 if they are immediate successors of certain CALL_INSNs. This
2884 allows the port to favor filling the delay slot of the call with
2885 the unconditional jump. */
2886 if (slots_to_fill
== 0)
2890 target_label
= JUMP_LABEL (insn
);
2891 condition
= get_branch_condition (insn
, target_label
);
2896 /* Get the next active fallthrough and target insns and see if we own
2897 them. Then see whether the branch is likely true. We don't need
2898 to do a lot of this for unconditional branches. */
2900 insn_at_target
= first_active_target_insn (target_label
);
2901 own_target
= own_thread_p (target_label
, target_label
, 0);
2903 if (condition
== const_true_rtx
)
2905 own_fallthrough
= 0;
2906 fallthrough_insn
= 0;
2911 fallthrough_insn
= next_active_insn (insn
);
2912 own_fallthrough
= own_thread_p (NEXT_INSN (insn
), NULL_RTX
, 1);
2913 prediction
= mostly_true_jump (insn
);
2916 /* If this insn is expected to branch, first try to get insns from our
2917 target, then our fallthrough insns. If it is not expected to branch,
2918 try the other order. */
2923 = fill_slots_from_thread (insn
, condition
, insn_at_target
,
2924 fallthrough_insn
, prediction
== 2, 1,
2926 slots_to_fill
, &slots_filled
, delay_list
);
2928 if (delay_list
== 0 && own_fallthrough
)
2930 /* Even though we didn't find anything for delay slots,
2931 we might have found a redundant insn which we deleted
2932 from the thread that was filled. So we have to recompute
2933 the next insn at the target. */
2934 target_label
= JUMP_LABEL (insn
);
2935 insn_at_target
= first_active_target_insn (target_label
);
2938 = fill_slots_from_thread (insn
, condition
, fallthrough_insn
,
2939 insn_at_target
, 0, 0,
2941 slots_to_fill
, &slots_filled
,
2947 if (own_fallthrough
)
2949 = fill_slots_from_thread (insn
, condition
, fallthrough_insn
,
2950 insn_at_target
, 0, 0,
2952 slots_to_fill
, &slots_filled
,
2955 if (delay_list
== 0)
2957 = fill_slots_from_thread (insn
, condition
, insn_at_target
,
2958 next_active_insn (insn
), 0, 1,
2960 slots_to_fill
, &slots_filled
,
2965 unfilled_slots_base
[i
]
2966 = emit_delay_sequence (insn
, delay_list
, slots_filled
);
2968 if (slots_to_fill
== slots_filled
)
2969 unfilled_slots_base
[i
] = 0;
2971 note_delay_statistics (slots_filled
, 1);
2975 static void delete_computation (rtx insn
);
2977 /* Recursively delete prior insns that compute the value (used only by INSN
2978 which the caller is deleting) stored in the register mentioned by NOTE
2979 which is a REG_DEAD note associated with INSN. */
2982 delete_prior_computation (rtx note
, rtx insn
)
2985 rtx reg
= XEXP (note
, 0);
2987 for (our_prev
= prev_nonnote_insn (insn
);
2988 our_prev
&& (NONJUMP_INSN_P (our_prev
)
2989 || CALL_P (our_prev
));
2990 our_prev
= prev_nonnote_insn (our_prev
))
2992 rtx pat
= PATTERN (our_prev
);
2994 /* If we reach a CALL which is not calling a const function
2995 or the callee pops the arguments, then give up. */
2996 if (CALL_P (our_prev
)
2997 && (! RTL_CONST_CALL_P (our_prev
)
2998 || GET_CODE (pat
) != SET
|| GET_CODE (SET_SRC (pat
)) != CALL
))
3001 /* If we reach a SEQUENCE, it is too complex to try to
3002 do anything with it, so give up. We can be run during
3003 and after reorg, so SEQUENCE rtl can legitimately show
3005 if (GET_CODE (pat
) == SEQUENCE
)
3008 if (GET_CODE (pat
) == USE
3009 && NONJUMP_INSN_P (XEXP (pat
, 0)))
3010 /* reorg creates USEs that look like this. We leave them
3011 alone because reorg needs them for its own purposes. */
3014 if (reg_set_p (reg
, pat
))
3016 if (side_effects_p (pat
) && !CALL_P (our_prev
))
3019 if (GET_CODE (pat
) == PARALLEL
)
3021 /* If we find a SET of something else, we can't
3026 for (i
= 0; i
< XVECLEN (pat
, 0); i
++)
3028 rtx part
= XVECEXP (pat
, 0, i
);
3030 if (GET_CODE (part
) == SET
3031 && SET_DEST (part
) != reg
)
3035 if (i
== XVECLEN (pat
, 0))
3036 delete_computation (our_prev
);
3038 else if (GET_CODE (pat
) == SET
3039 && REG_P (SET_DEST (pat
)))
3041 int dest_regno
= REGNO (SET_DEST (pat
));
3042 int dest_endregno
= END_REGNO (SET_DEST (pat
));
3043 int regno
= REGNO (reg
);
3044 int endregno
= END_REGNO (reg
);
3046 if (dest_regno
>= regno
3047 && dest_endregno
<= endregno
)
3048 delete_computation (our_prev
);
3050 /* We may have a multi-word hard register and some, but not
3051 all, of the words of the register are needed in subsequent
3052 insns. Write REG_UNUSED notes for those parts that were not
3054 else if (dest_regno
<= regno
3055 && dest_endregno
>= endregno
)
3059 add_reg_note (our_prev
, REG_UNUSED
, reg
);
3061 for (i
= dest_regno
; i
< dest_endregno
; i
++)
3062 if (! find_regno_note (our_prev
, REG_UNUSED
, i
))
3065 if (i
== dest_endregno
)
3066 delete_computation (our_prev
);
3073 /* If PAT references the register that dies here, it is an
3074 additional use. Hence any prior SET isn't dead. However, this
3075 insn becomes the new place for the REG_DEAD note. */
3076 if (reg_overlap_mentioned_p (reg
, pat
))
3078 XEXP (note
, 1) = REG_NOTES (our_prev
);
3079 REG_NOTES (our_prev
) = note
;
3085 /* Delete INSN and recursively delete insns that compute values used only
3086 by INSN. This uses the REG_DEAD notes computed during flow analysis.
3088 Look at all our REG_DEAD notes. If a previous insn does nothing other
3089 than set a register that dies in this insn, we can delete that insn
3092 On machines with CC0, if CC0 is used in this insn, we may be able to
3093 delete the insn that set it. */
3096 delete_computation (rtx insn
)
3101 if (reg_referenced_p (cc0_rtx
, PATTERN (insn
)))
3103 rtx prev
= prev_nonnote_insn (insn
);
3104 /* We assume that at this stage
3105 CC's are always set explicitly
3106 and always immediately before the jump that
3107 will use them. So if the previous insn
3108 exists to set the CC's, delete it
3109 (unless it performs auto-increments, etc.). */
3110 if (prev
&& NONJUMP_INSN_P (prev
)
3111 && sets_cc0_p (PATTERN (prev
)))
3113 if (sets_cc0_p (PATTERN (prev
)) > 0
3114 && ! side_effects_p (PATTERN (prev
)))
3115 delete_computation (prev
);
3117 /* Otherwise, show that cc0 won't be used. */
3118 add_reg_note (prev
, REG_UNUSED
, cc0_rtx
);
3123 for (note
= REG_NOTES (insn
); note
; note
= next
)
3125 next
= XEXP (note
, 1);
3127 if (REG_NOTE_KIND (note
) != REG_DEAD
3128 /* Verify that the REG_NOTE is legitimate. */
3129 || !REG_P (XEXP (note
, 0)))
3132 delete_prior_computation (note
, insn
);
3135 delete_related_insns (insn
);
3138 /* If all INSN does is set the pc, delete it,
3139 and delete the insn that set the condition codes for it
3140 if that's what the previous thing was. */
3143 delete_jump (rtx_insn
*insn
)
3145 rtx set
= single_set (insn
);
3147 if (set
&& GET_CODE (SET_DEST (set
)) == PC
)
3148 delete_computation (insn
);
3152 label_before_next_insn (rtx x
, rtx scan_limit
)
3154 rtx_insn
*insn
= next_active_insn (x
);
3157 insn
= PREV_INSN (insn
);
3158 if (insn
== scan_limit
|| insn
== NULL_RTX
)
3167 /* Once we have tried two ways to fill a delay slot, make a pass over the
3168 code to try to improve the results and to do such things as more jump
3172 relax_delay_slots (rtx_insn
*first
)
3174 rtx_insn
*insn
, *next
;
3177 rtx_insn
*delay_insn
;
3180 /* Look at every JUMP_INSN and see if we can improve it. */
3181 for (insn
= first
; insn
; insn
= next
)
3186 next
= next_active_insn (insn
);
3188 /* If this is a jump insn, see if it now jumps to a jump, jumps to
3189 the next insn, or jumps to a label that is not the last of a
3190 group of consecutive labels. */
3192 && (condjump_p (insn
) || condjump_in_parallel_p (insn
))
3193 && !ANY_RETURN_P (target_label
= JUMP_LABEL (insn
)))
3196 = skip_consecutive_labels (follow_jumps (target_label
, insn
,
3198 if (ANY_RETURN_P (target_label
))
3199 target_label
= find_end_label (target_label
);
3201 if (target_label
&& next_active_insn (target_label
) == next
3202 && ! condjump_in_parallel_p (insn
))
3208 if (target_label
&& target_label
!= JUMP_LABEL (insn
))
3210 reorg_redirect_jump (insn
, target_label
);
3212 CROSSING_JUMP_P (insn
) = 1;
3215 /* See if this jump conditionally branches around an unconditional
3216 jump. If so, invert this jump and point it to the target of the
3218 if (next
&& simplejump_or_return_p (next
)
3219 && any_condjump_p (insn
)
3221 && next_active_insn (target_label
) == next_active_insn (next
)
3222 && no_labels_between_p (insn
, next
))
3224 rtx label
= JUMP_LABEL (next
);
3226 /* Be careful how we do this to avoid deleting code or
3227 labels that are momentarily dead. See similar optimization
3230 We also need to ensure we properly handle the case when
3231 invert_jump fails. */
3233 ++LABEL_NUSES (target_label
);
3234 if (!ANY_RETURN_P (label
))
3235 ++LABEL_NUSES (label
);
3237 if (invert_jump (insn
, label
, 1))
3239 delete_related_insns (next
);
3243 if (!ANY_RETURN_P (label
))
3244 --LABEL_NUSES (label
);
3246 if (--LABEL_NUSES (target_label
) == 0)
3247 delete_related_insns (target_label
);
3253 /* If this is an unconditional jump and the previous insn is a
3254 conditional jump, try reversing the condition of the previous
3255 insn and swapping our targets. The next pass might be able to
3258 Don't do this if we expect the conditional branch to be true, because
3259 we would then be making the more common case longer. */
3261 if (simplejump_or_return_p (insn
)
3262 && (other
= prev_active_insn (insn
)) != 0
3263 && any_condjump_p (other
)
3264 && no_labels_between_p (other
, insn
)
3265 && 0 > mostly_true_jump (other
))
3267 rtx other_target
= JUMP_LABEL (other
);
3268 target_label
= JUMP_LABEL (insn
);
3270 if (invert_jump (other
, target_label
, 0))
3271 reorg_redirect_jump (insn
, other_target
);
3274 /* Now look only at cases where we have a filled delay slot. */
3275 if (!NONJUMP_INSN_P (insn
) || GET_CODE (PATTERN (insn
)) != SEQUENCE
)
3278 pat
= as_a
<rtx_sequence
*> (PATTERN (insn
));
3279 delay_insn
= pat
->insn (0);
3281 /* See if the first insn in the delay slot is redundant with some
3282 previous insn. Remove it from the delay slot if so; then set up
3283 to reprocess this insn. */
3284 if (redundant_insn (pat
->insn (1), delay_insn
, 0))
3286 update_block (pat
->insn (1), insn
);
3287 delete_from_delay_slot (pat
->insn (1));
3288 next
= prev_active_insn (next
);
3292 /* See if we have a RETURN insn with a filled delay slot followed
3293 by a RETURN insn with an unfilled a delay slot. If so, we can delete
3294 the first RETURN (but not its delay insn). This gives the same
3295 effect in fewer instructions.
3297 Only do so if optimizing for size since this results in slower, but
3299 if (optimize_function_for_size_p (cfun
)
3300 && ANY_RETURN_P (PATTERN (delay_insn
))
3303 && PATTERN (next
) == PATTERN (delay_insn
))
3308 /* Delete the RETURN and just execute the delay list insns.
3310 We do this by deleting the INSN containing the SEQUENCE, then
3311 re-emitting the insns separately, and then deleting the RETURN.
3312 This allows the count of the jump target to be properly
3315 Note that we need to change the INSN_UID of the re-emitted insns
3316 since it is used to hash the insns for mark_target_live_regs and
3317 the re-emitted insns will no longer be wrapped up in a SEQUENCE.
3319 Clear the from target bit, since these insns are no longer
3321 for (i
= 0; i
< XVECLEN (pat
, 0); i
++)
3322 INSN_FROM_TARGET_P (XVECEXP (pat
, 0, i
)) = 0;
3324 trial
= PREV_INSN (insn
);
3325 delete_related_insns (insn
);
3326 gcc_assert (GET_CODE (pat
) == SEQUENCE
);
3327 add_insn_after (delay_insn
, trial
, NULL
);
3329 for (i
= 1; i
< pat
->len (); i
++)
3330 after
= emit_copy_of_insn_after (pat
->insn (i
), after
);
3331 delete_scheduled_jump (delay_insn
);
3335 /* Now look only at the cases where we have a filled JUMP_INSN. */
3336 if (!JUMP_P (delay_insn
)
3337 || !(condjump_p (delay_insn
) || condjump_in_parallel_p (delay_insn
)))
3340 target_label
= JUMP_LABEL (delay_insn
);
3341 if (target_label
&& ANY_RETURN_P (target_label
))
3344 /* If this jump goes to another unconditional jump, thread it, but
3345 don't convert a jump into a RETURN here. */
3346 trial
= skip_consecutive_labels (follow_jumps (target_label
, delay_insn
,
3348 if (ANY_RETURN_P (trial
))
3349 trial
= find_end_label (trial
);
3351 if (trial
&& trial
!= target_label
3352 && redirect_with_delay_slots_safe_p (delay_insn
, trial
, insn
))
3354 reorg_redirect_jump (delay_insn
, trial
);
3355 target_label
= trial
;
3357 CROSSING_JUMP_P (insn
) = 1;
3360 /* If the first insn at TARGET_LABEL is redundant with a previous
3361 insn, redirect the jump to the following insn and process again.
3362 We use next_real_insn instead of next_active_insn so we
3363 don't skip USE-markers, or we'll end up with incorrect
3365 trial
= next_real_insn (target_label
);
3366 if (trial
&& GET_CODE (PATTERN (trial
)) != SEQUENCE
3367 && redundant_insn (trial
, insn
, 0)
3368 && ! can_throw_internal (trial
))
3370 /* Figure out where to emit the special USE insn so we don't
3371 later incorrectly compute register live/death info. */
3372 rtx_insn
*tmp
= next_active_insn (trial
);
3374 tmp
= find_end_label (simple_return_rtx
);
3378 /* Insert the special USE insn and update dataflow info.
3379 We know "trial" is an insn here as it is the output of
3380 next_real_insn () above. */
3381 update_block (as_a
<rtx_insn
*> (trial
), tmp
);
3383 /* Now emit a label before the special USE insn, and
3384 redirect our jump to the new label. */
3385 target_label
= get_label_before (PREV_INSN (tmp
), target_label
);
3386 reorg_redirect_jump (delay_insn
, target_label
);
3392 /* Similarly, if it is an unconditional jump with one insn in its
3393 delay list and that insn is redundant, thread the jump. */
3394 rtx_sequence
*trial_seq
=
3395 trial
? dyn_cast
<rtx_sequence
*> (PATTERN (trial
)) : NULL
;
3397 && trial_seq
->len () == 2
3398 && JUMP_P (trial_seq
->insn (0))
3399 && simplejump_or_return_p (trial_seq
->insn (0))
3400 && redundant_insn (trial_seq
->insn (1), insn
, 0))
3402 target_label
= JUMP_LABEL (trial_seq
->insn (0));
3403 if (ANY_RETURN_P (target_label
))
3404 target_label
= find_end_label (target_label
);
3407 && redirect_with_delay_slots_safe_p (delay_insn
, target_label
,
3410 update_block (trial_seq
->insn (1), insn
);
3411 reorg_redirect_jump (delay_insn
, target_label
);
3417 /* See if we have a simple (conditional) jump that is useless. */
3418 if (! INSN_ANNULLED_BRANCH_P (delay_insn
)
3419 && ! condjump_in_parallel_p (delay_insn
)
3420 && prev_active_insn (target_label
) == insn
3421 && ! BARRIER_P (prev_nonnote_insn (target_label
))
3423 /* If the last insn in the delay slot sets CC0 for some insn,
3424 various code assumes that it is in a delay slot. We could
3425 put it back where it belonged and delete the register notes,
3426 but it doesn't seem worthwhile in this uncommon case. */
3427 && ! find_reg_note (XVECEXP (pat
, 0, XVECLEN (pat
, 0) - 1),
3428 REG_CC_USER
, NULL_RTX
)
3435 /* All this insn does is execute its delay list and jump to the
3436 following insn. So delete the jump and just execute the delay
3439 We do this by deleting the INSN containing the SEQUENCE, then
3440 re-emitting the insns separately, and then deleting the jump.
3441 This allows the count of the jump target to be properly
3444 Note that we need to change the INSN_UID of the re-emitted insns
3445 since it is used to hash the insns for mark_target_live_regs and
3446 the re-emitted insns will no longer be wrapped up in a SEQUENCE.
3448 Clear the from target bit, since these insns are no longer
3450 for (i
= 0; i
< XVECLEN (pat
, 0); i
++)
3451 INSN_FROM_TARGET_P (XVECEXP (pat
, 0, i
)) = 0;
3453 trial
= PREV_INSN (insn
);
3454 delete_related_insns (insn
);
3455 gcc_assert (GET_CODE (pat
) == SEQUENCE
);
3456 add_insn_after (delay_insn
, trial
, NULL
);
3458 for (i
= 1; i
< pat
->len (); i
++)
3459 after
= emit_copy_of_insn_after (pat
->insn (i
), after
);
3460 delete_scheduled_jump (delay_insn
);
3464 /* See if this is an unconditional jump around a single insn which is
3465 identical to the one in its delay slot. In this case, we can just
3466 delete the branch and the insn in its delay slot. */
3467 if (next
&& NONJUMP_INSN_P (next
)
3468 && label_before_next_insn (next
, insn
) == target_label
3469 && simplejump_p (insn
)
3470 && XVECLEN (pat
, 0) == 2
3471 && rtx_equal_p (PATTERN (next
), PATTERN (pat
->insn (1))))
3473 delete_related_insns (insn
);
3477 /* See if this jump (with its delay slots) conditionally branches
3478 around an unconditional jump (without delay slots). If so, invert
3479 this jump and point it to the target of the second jump. We cannot
3480 do this for annulled jumps, though. Again, don't convert a jump to
3482 if (! INSN_ANNULLED_BRANCH_P (delay_insn
)
3483 && any_condjump_p (delay_insn
)
3484 && next
&& simplejump_or_return_p (next
)
3485 && next_active_insn (target_label
) == next_active_insn (next
)
3486 && no_labels_between_p (insn
, next
))
3488 rtx label
= JUMP_LABEL (next
);
3489 rtx old_label
= JUMP_LABEL (delay_insn
);
3491 if (ANY_RETURN_P (label
))
3492 label
= find_end_label (label
);
3494 /* find_end_label can generate a new label. Check this first. */
3496 && no_labels_between_p (insn
, next
)
3497 && redirect_with_delay_slots_safe_p (delay_insn
, label
, insn
))
3499 /* Be careful how we do this to avoid deleting code or labels
3500 that are momentarily dead. See similar optimization in
3503 ++LABEL_NUSES (old_label
);
3505 if (invert_jump (delay_insn
, label
, 1))
3509 /* Must update the INSN_FROM_TARGET_P bits now that
3510 the branch is reversed, so that mark_target_live_regs
3511 will handle the delay slot insn correctly. */
3512 for (i
= 1; i
< XVECLEN (PATTERN (insn
), 0); i
++)
3514 rtx slot
= XVECEXP (PATTERN (insn
), 0, i
);
3515 INSN_FROM_TARGET_P (slot
) = ! INSN_FROM_TARGET_P (slot
);
3518 delete_related_insns (next
);
3522 if (old_label
&& --LABEL_NUSES (old_label
) == 0)
3523 delete_related_insns (old_label
);
3528 /* If we own the thread opposite the way this insn branches, see if we
3529 can merge its delay slots with following insns. */
3530 if (INSN_FROM_TARGET_P (pat
->insn (1))
3531 && own_thread_p (NEXT_INSN (insn
), 0, 1))
3532 try_merge_delay_insns (insn
, next
);
3533 else if (! INSN_FROM_TARGET_P (pat
->insn (1))
3534 && own_thread_p (target_label
, target_label
, 0))
3535 try_merge_delay_insns (insn
, next_active_insn (target_label
));
3537 /* If we get here, we haven't deleted INSN. But we may have deleted
3538 NEXT, so recompute it. */
3539 next
= next_active_insn (insn
);
3544 /* Look for filled jumps to the end of function label. We can try to convert
3545 them into RETURN insns if the insns in the delay slot are valid for the
3549 make_return_insns (rtx_insn
*first
)
3552 rtx_insn
*jump_insn
;
3553 rtx real_return_label
= function_return_label
;
3554 rtx real_simple_return_label
= function_simple_return_label
;
3557 /* See if there is a RETURN insn in the function other than the one we
3558 made for END_OF_FUNCTION_LABEL. If so, set up anything we can't change
3559 into a RETURN to jump to it. */
3560 for (insn
= first
; insn
; insn
= NEXT_INSN (insn
))
3561 if (JUMP_P (insn
) && ANY_RETURN_P (PATTERN (insn
)))
3563 rtx t
= get_label_before (insn
, NULL_RTX
);
3564 if (PATTERN (insn
) == ret_rtx
)
3565 real_return_label
= t
;
3567 real_simple_return_label
= t
;
3571 /* Show an extra usage of REAL_RETURN_LABEL so it won't go away if it
3572 was equal to END_OF_FUNCTION_LABEL. */
3573 if (real_return_label
)
3574 LABEL_NUSES (real_return_label
)++;
3575 if (real_simple_return_label
)
3576 LABEL_NUSES (real_simple_return_label
)++;
3578 /* Clear the list of insns to fill so we can use it. */
3579 obstack_free (&unfilled_slots_obstack
, unfilled_firstobj
);
3581 for (insn
= first
; insn
; insn
= NEXT_INSN (insn
))
3584 rtx kind
, real_label
;
3586 /* Only look at filled JUMP_INSNs that go to the end of function
3588 if (!NONJUMP_INSN_P (insn
))
3591 if (GET_CODE (PATTERN (insn
)) != SEQUENCE
)
3594 rtx_sequence
*pat
= as_a
<rtx_sequence
*> (PATTERN (insn
));
3596 if (!jump_to_label_p (pat
->insn (0)))
3599 if (JUMP_LABEL (pat
->insn (0)) == function_return_label
)
3602 real_label
= real_return_label
;
3604 else if (JUMP_LABEL (pat
->insn (0)) == function_simple_return_label
)
3606 kind
= simple_return_rtx
;
3607 real_label
= real_simple_return_label
;
3612 jump_insn
= pat
->insn (0);
3614 /* If we can't make the jump into a RETURN, try to redirect it to the best
3615 RETURN and go on to the next insn. */
3616 if (!reorg_redirect_jump (jump_insn
, kind
))
3618 /* Make sure redirecting the jump will not invalidate the delay
3620 if (redirect_with_delay_slots_safe_p (jump_insn
, real_label
, insn
))
3621 reorg_redirect_jump (jump_insn
, real_label
);
3625 /* See if this RETURN can accept the insns current in its delay slot.
3626 It can if it has more or an equal number of slots and the contents
3627 of each is valid. */
3629 flags
= get_jump_flags (jump_insn
, JUMP_LABEL (jump_insn
));
3630 slots
= num_delay_slots (jump_insn
);
3631 if (slots
>= XVECLEN (pat
, 0) - 1)
3633 for (i
= 1; i
< XVECLEN (pat
, 0); i
++)
3635 #ifdef ANNUL_IFFALSE_SLOTS
3636 (INSN_ANNULLED_BRANCH_P (jump_insn
)
3637 && INSN_FROM_TARGET_P (pat
->insn (i
)))
3638 ? eligible_for_annul_false (jump_insn
, i
- 1,
3639 pat
->insn (i
), flags
) :
3641 #ifdef ANNUL_IFTRUE_SLOTS
3642 (INSN_ANNULLED_BRANCH_P (jump_insn
)
3643 && ! INSN_FROM_TARGET_P (pat
->insn (i
)))
3644 ? eligible_for_annul_true (jump_insn
, i
- 1,
3645 pat
->insn (i
), flags
) :
3647 eligible_for_delay (jump_insn
, i
- 1,
3648 pat
->insn (i
), flags
)))
3654 if (i
== XVECLEN (pat
, 0))
3657 /* We have to do something with this insn. If it is an unconditional
3658 RETURN, delete the SEQUENCE and output the individual insns,
3659 followed by the RETURN. Then set things up so we try to find
3660 insns for its delay slots, if it needs some. */
3661 if (ANY_RETURN_P (PATTERN (jump_insn
)))
3663 rtx_insn
*prev
= PREV_INSN (insn
);
3665 delete_related_insns (insn
);
3666 for (i
= 1; i
< XVECLEN (pat
, 0); i
++)
3667 prev
= emit_insn_after (PATTERN (XVECEXP (pat
, 0, i
)), prev
);
3669 insn
= emit_jump_insn_after (PATTERN (jump_insn
), prev
);
3670 emit_barrier_after (insn
);
3673 obstack_ptr_grow (&unfilled_slots_obstack
, insn
);
3676 /* It is probably more efficient to keep this with its current
3677 delay slot as a branch to a RETURN. */
3678 reorg_redirect_jump (jump_insn
, real_label
);
3681 /* Now delete REAL_RETURN_LABEL if we never used it. Then try to fill any
3682 new delay slots we have created. */
3683 if (real_return_label
!= NULL_RTX
&& --LABEL_NUSES (real_return_label
) == 0)
3684 delete_related_insns (real_return_label
);
3685 if (real_simple_return_label
!= NULL_RTX
3686 && --LABEL_NUSES (real_simple_return_label
) == 0)
3687 delete_related_insns (real_simple_return_label
);
3689 fill_simple_delay_slots (1);
3690 fill_simple_delay_slots (0);
3693 /* Try to find insns to place in delay slots. */
3696 dbr_schedule (rtx_insn
*first
)
3698 rtx_insn
*insn
, *next
, *epilogue_insn
= 0;
3700 bool need_return_insns
;
3702 /* If the current function has no insns other than the prologue and
3703 epilogue, then do not try to fill any delay slots. */
3704 if (n_basic_blocks_for_fn (cfun
) == NUM_FIXED_BLOCKS
)
3707 /* Find the highest INSN_UID and allocate and initialize our map from
3708 INSN_UID's to position in code. */
3709 for (max_uid
= 0, insn
= first
; insn
; insn
= NEXT_INSN (insn
))
3711 if (INSN_UID (insn
) > max_uid
)
3712 max_uid
= INSN_UID (insn
);
3714 && NOTE_KIND (insn
) == NOTE_INSN_EPILOGUE_BEG
)
3715 epilogue_insn
= insn
;
3718 uid_to_ruid
= XNEWVEC (int, max_uid
+ 1);
3719 for (i
= 0, insn
= first
; insn
; i
++, insn
= NEXT_INSN (insn
))
3720 uid_to_ruid
[INSN_UID (insn
)] = i
;
3722 /* Initialize the list of insns that need filling. */
3723 if (unfilled_firstobj
== 0)
3725 gcc_obstack_init (&unfilled_slots_obstack
);
3726 unfilled_firstobj
= XOBNEWVAR (&unfilled_slots_obstack
, rtx
, 0);
3729 for (insn
= next_active_insn (first
); insn
; insn
= next_active_insn (insn
))
3733 /* Skip vector tables. We can't get attributes for them. */
3734 if (JUMP_TABLE_DATA_P (insn
))
3738 INSN_ANNULLED_BRANCH_P (insn
) = 0;
3739 INSN_FROM_TARGET_P (insn
) = 0;
3741 if (num_delay_slots (insn
) > 0)
3742 obstack_ptr_grow (&unfilled_slots_obstack
, insn
);
3744 /* Ensure all jumps go to the last of a set of consecutive labels. */
3746 && (condjump_p (insn
) || condjump_in_parallel_p (insn
))
3747 && !ANY_RETURN_P (JUMP_LABEL (insn
))
3748 && ((target
= skip_consecutive_labels (JUMP_LABEL (insn
)))
3749 != JUMP_LABEL (insn
)))
3750 redirect_jump (insn
, target
, 1);
3753 init_resource_info (epilogue_insn
);
3755 /* Show we haven't computed an end-of-function label yet. */
3756 function_return_label
= function_simple_return_label
= NULL
;
3758 /* Initialize the statistics for this function. */
3759 memset (num_insns_needing_delays
, 0, sizeof num_insns_needing_delays
);
3760 memset (num_filled_delays
, 0, sizeof num_filled_delays
);
3762 /* Now do the delay slot filling. Try everything twice in case earlier
3763 changes make more slots fillable. */
3765 for (reorg_pass_number
= 0;
3766 reorg_pass_number
< MAX_REORG_PASSES
;
3767 reorg_pass_number
++)
3769 fill_simple_delay_slots (1);
3770 fill_simple_delay_slots (0);
3771 fill_eager_delay_slots ();
3772 relax_delay_slots (first
);
3775 /* If we made an end of function label, indicate that it is now
3776 safe to delete it by undoing our prior adjustment to LABEL_NUSES.
3777 If it is now unused, delete it. */
3778 if (function_return_label
&& --LABEL_NUSES (function_return_label
) == 0)
3779 delete_related_insns (function_return_label
);
3780 if (function_simple_return_label
3781 && --LABEL_NUSES (function_simple_return_label
) == 0)
3782 delete_related_insns (function_simple_return_label
);
3784 need_return_insns
= false;
3786 need_return_insns
|= HAVE_return
&& function_return_label
!= 0;
3788 #ifdef HAVE_simple_return
3789 need_return_insns
|= HAVE_simple_return
&& function_simple_return_label
!= 0;
3791 if (need_return_insns
)
3792 make_return_insns (first
);
3794 /* Delete any USE insns made by update_block; subsequent passes don't need
3795 them or know how to deal with them. */
3796 for (insn
= first
; insn
; insn
= next
)
3798 next
= NEXT_INSN (insn
);
3800 if (NONJUMP_INSN_P (insn
) && GET_CODE (PATTERN (insn
)) == USE
3801 && INSN_P (XEXP (PATTERN (insn
), 0)))
3802 next
= delete_related_insns (insn
);
3805 obstack_free (&unfilled_slots_obstack
, unfilled_firstobj
);
3807 /* It is not clear why the line below is needed, but it does seem to be. */
3808 unfilled_firstobj
= XOBNEWVAR (&unfilled_slots_obstack
, rtx
, 0);
3812 int i
, j
, need_comma
;
3813 int total_delay_slots
[MAX_DELAY_HISTOGRAM
+ 1];
3814 int total_annul_slots
[MAX_DELAY_HISTOGRAM
+ 1];
3816 for (reorg_pass_number
= 0;
3817 reorg_pass_number
< MAX_REORG_PASSES
;
3818 reorg_pass_number
++)
3820 fprintf (dump_file
, ";; Reorg pass #%d:\n", reorg_pass_number
+ 1);
3821 for (i
= 0; i
< NUM_REORG_FUNCTIONS
; i
++)
3824 fprintf (dump_file
, ";; Reorg function #%d\n", i
);
3826 fprintf (dump_file
, ";; %d insns needing delay slots\n;; ",
3827 num_insns_needing_delays
[i
][reorg_pass_number
]);
3829 for (j
= 0; j
< MAX_DELAY_HISTOGRAM
+ 1; j
++)
3830 if (num_filled_delays
[i
][j
][reorg_pass_number
])
3833 fprintf (dump_file
, ", ");
3835 fprintf (dump_file
, "%d got %d delays",
3836 num_filled_delays
[i
][j
][reorg_pass_number
], j
);
3838 fprintf (dump_file
, "\n");
3841 memset (total_delay_slots
, 0, sizeof total_delay_slots
);
3842 memset (total_annul_slots
, 0, sizeof total_annul_slots
);
3843 for (insn
= first
; insn
; insn
= NEXT_INSN (insn
))
3845 if (! insn
->deleted ()
3846 && NONJUMP_INSN_P (insn
)
3847 && GET_CODE (PATTERN (insn
)) != USE
3848 && GET_CODE (PATTERN (insn
)) != CLOBBER
)
3850 if (GET_CODE (PATTERN (insn
)) == SEQUENCE
)
3853 j
= XVECLEN (PATTERN (insn
), 0) - 1;
3854 if (j
> MAX_DELAY_HISTOGRAM
)
3855 j
= MAX_DELAY_HISTOGRAM
;
3856 control
= XVECEXP (PATTERN (insn
), 0, 0);
3857 if (JUMP_P (control
) && INSN_ANNULLED_BRANCH_P (control
))
3858 total_annul_slots
[j
]++;
3860 total_delay_slots
[j
]++;
3862 else if (num_delay_slots (insn
) > 0)
3863 total_delay_slots
[0]++;
3866 fprintf (dump_file
, ";; Reorg totals: ");
3868 for (j
= 0; j
< MAX_DELAY_HISTOGRAM
+ 1; j
++)
3870 if (total_delay_slots
[j
])
3873 fprintf (dump_file
, ", ");
3875 fprintf (dump_file
, "%d got %d delays", total_delay_slots
[j
], j
);
3878 fprintf (dump_file
, "\n");
3879 #if defined (ANNUL_IFTRUE_SLOTS) || defined (ANNUL_IFFALSE_SLOTS)
3880 fprintf (dump_file
, ";; Reorg annuls: ");
3882 for (j
= 0; j
< MAX_DELAY_HISTOGRAM
+ 1; j
++)
3884 if (total_annul_slots
[j
])
3887 fprintf (dump_file
, ", ");
3889 fprintf (dump_file
, "%d got %d delays", total_annul_slots
[j
], j
);
3892 fprintf (dump_file
, "\n");
3894 fprintf (dump_file
, "\n");
3897 if (!sibling_labels
.is_empty ())
3899 update_alignments (sibling_labels
);
3900 sibling_labels
.release ();
3903 free_resource_info ();
3905 crtl
->dbr_scheduled_p
= true;
3907 #endif /* DELAY_SLOTS */
3909 /* Run delay slot optimization. */
3911 rest_of_handle_delay_slots (void)
3914 dbr_schedule (get_insns ());
3921 const pass_data pass_data_delay_slots
=
3923 RTL_PASS
, /* type */
3925 OPTGROUP_NONE
, /* optinfo_flags */
3926 TV_DBR_SCHED
, /* tv_id */
3927 0, /* properties_required */
3928 0, /* properties_provided */
3929 0, /* properties_destroyed */
3930 0, /* todo_flags_start */
3931 0, /* todo_flags_finish */
3934 class pass_delay_slots
: public rtl_opt_pass
3937 pass_delay_slots (gcc::context
*ctxt
)
3938 : rtl_opt_pass (pass_data_delay_slots
, ctxt
)
3941 /* opt_pass methods: */
3942 virtual bool gate (function
*);
3943 virtual unsigned int execute (function
*)
3945 return rest_of_handle_delay_slots ();
3948 }; // class pass_delay_slots
3951 pass_delay_slots::gate (function
*)
3954 /* At -O0 dataflow info isn't updated after RA. */
3955 return optimize
> 0 && flag_delayed_branch
&& !crtl
->dbr_scheduled_p
;
3964 make_pass_delay_slots (gcc::context
*ctxt
)
3966 return new pass_delay_slots (ctxt
);
3969 /* Machine dependent reorg pass. */
3973 const pass_data pass_data_machine_reorg
=
3975 RTL_PASS
, /* type */
3977 OPTGROUP_NONE
, /* optinfo_flags */
3978 TV_MACH_DEP
, /* tv_id */
3979 0, /* properties_required */
3980 0, /* properties_provided */
3981 0, /* properties_destroyed */
3982 0, /* todo_flags_start */
3983 0, /* todo_flags_finish */
3986 class pass_machine_reorg
: public rtl_opt_pass
3989 pass_machine_reorg (gcc::context
*ctxt
)
3990 : rtl_opt_pass (pass_data_machine_reorg
, ctxt
)
3993 /* opt_pass methods: */
3994 virtual bool gate (function
*)
3996 return targetm
.machine_dependent_reorg
!= 0;
3999 virtual unsigned int execute (function
*)
4001 targetm
.machine_dependent_reorg ();
4005 }; // class pass_machine_reorg
4010 make_pass_machine_reorg (gcc::context
*ctxt
)
4012 return new pass_machine_reorg (ctxt
);