1 /* Perform instruction reorganizations for delay slot filling.
2 Copyright (C) 1992-2016 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"
111 #include "memmodel.h"
114 #include "insn-config.h"
115 #include "emit-rtl.h"
117 #include "insn-attr.h"
118 #include "resource.h"
120 #include "tree-pass.h"
123 /* First, some functions that were used before GCC got a control flow graph.
124 These functions are now only used here in reorg.c, and have therefore
125 been moved here to avoid inadvertent misuse elsewhere in the compiler. */
127 /* Return the last label to mark the same position as LABEL. Return LABEL
128 itself if it is null or any return rtx. */
131 skip_consecutive_labels (rtx label_or_return
)
135 if (label_or_return
&& ANY_RETURN_P (label_or_return
))
136 return label_or_return
;
138 rtx_insn
*label
= as_a
<rtx_insn
*> (label_or_return
);
140 for (insn
= label
; insn
!= 0 && !INSN_P (insn
); insn
= NEXT_INSN (insn
))
147 /* INSN uses CC0 and is being moved into a delay slot. Set up REG_CC_SETTER
148 and REG_CC_USER notes so we can find it. */
151 link_cc0_insns (rtx_insn
*insn
)
153 rtx user
= next_nonnote_insn (insn
);
155 if (NONJUMP_INSN_P (user
) && GET_CODE (PATTERN (user
)) == SEQUENCE
)
156 user
= XVECEXP (PATTERN (user
), 0, 0);
158 add_reg_note (user
, REG_CC_SETTER
, insn
);
159 add_reg_note (insn
, REG_CC_USER
, user
);
162 /* Insns which have delay slots that have not yet been filled. */
164 static struct obstack unfilled_slots_obstack
;
165 static rtx
*unfilled_firstobj
;
167 /* Define macros to refer to the first and last slot containing unfilled
168 insns. These are used because the list may move and its address
169 should be recomputed at each use. */
171 #define unfilled_slots_base \
172 ((rtx_insn **) obstack_base (&unfilled_slots_obstack))
174 #define unfilled_slots_next \
175 ((rtx_insn **) obstack_next_free (&unfilled_slots_obstack))
177 /* Points to the label before the end of the function, or before a
179 static rtx_code_label
*function_return_label
;
180 /* Likewise for a simple_return. */
181 static rtx_code_label
*function_simple_return_label
;
183 /* Mapping between INSN_UID's and position in the code since INSN_UID's do
184 not always monotonically increase. */
185 static int *uid_to_ruid
;
187 /* Highest valid index in `uid_to_ruid'. */
190 static int stop_search_p (rtx_insn
*, int);
191 static int resource_conflicts_p (struct resources
*, struct resources
*);
192 static int insn_references_resource_p (rtx
, struct resources
*, bool);
193 static int insn_sets_resource_p (rtx
, struct resources
*, bool);
194 static rtx_code_label
*find_end_label (rtx
);
195 static rtx_insn
*emit_delay_sequence (rtx_insn
*, const vec
<rtx_insn
*> &,
197 static void add_to_delay_list (rtx_insn
*, vec
<rtx_insn
*> *);
198 static rtx_insn
*delete_from_delay_slot (rtx_insn
*);
199 static void delete_scheduled_jump (rtx_insn
*);
200 static void note_delay_statistics (int, int);
201 static int get_jump_flags (const rtx_insn
*, rtx
);
202 static int mostly_true_jump (rtx
);
203 static rtx
get_branch_condition (const rtx_insn
*, rtx
);
204 static int condition_dominates_p (rtx
, const rtx_insn
*);
205 static int redirect_with_delay_slots_safe_p (rtx_insn
*, rtx
, rtx
);
206 static int redirect_with_delay_list_safe_p (rtx_insn
*, rtx
,
207 const vec
<rtx_insn
*> &);
208 static int check_annul_list_true_false (int, const vec
<rtx_insn
*> &);
209 static void steal_delay_list_from_target (rtx_insn
*, rtx
, rtx_sequence
*,
216 static void steal_delay_list_from_fallthrough (rtx_insn
*, rtx
, rtx_sequence
*,
222 static void try_merge_delay_insns (rtx_insn
*, rtx_insn
*);
223 static rtx_insn
*redundant_insn (rtx
, rtx_insn
*, const vec
<rtx_insn
*> &);
224 static int own_thread_p (rtx
, rtx
, int);
225 static void update_block (rtx_insn
*, rtx
);
226 static int reorg_redirect_jump (rtx_jump_insn
*, rtx
);
227 static void update_reg_dead_notes (rtx_insn
*, rtx_insn
*);
228 static void fix_reg_dead_note (rtx_insn
*, rtx
);
229 static void update_reg_unused_notes (rtx
, rtx
);
230 static void fill_simple_delay_slots (int);
231 static void fill_slots_from_thread (rtx_jump_insn
*, rtx
, rtx
, rtx
,
233 int *, vec
<rtx_insn
*> *);
234 static void fill_eager_delay_slots (void);
235 static void relax_delay_slots (rtx_insn
*);
236 static void make_return_insns (rtx_insn
*);
238 /* A wrapper around next_active_insn which takes care to return ret_rtx
242 first_active_target_insn (rtx insn
)
244 if (ANY_RETURN_P (insn
))
246 return next_active_insn (as_a
<rtx_insn
*> (insn
));
249 /* Return true iff INSN is a simplejump, or any kind of return insn. */
252 simplejump_or_return_p (rtx insn
)
254 return (JUMP_P (insn
)
255 && (simplejump_p (as_a
<rtx_insn
*> (insn
))
256 || ANY_RETURN_P (PATTERN (insn
))));
259 /* Return TRUE if this insn should stop the search for insn to fill delay
260 slots. LABELS_P indicates that labels should terminate the search.
261 In all cases, jumps terminate the search. */
264 stop_search_p (rtx_insn
*insn
, int labels_p
)
269 /* If the insn can throw an exception that is caught within the function,
270 it may effectively perform a jump from the viewpoint of the function.
271 Therefore act like for a jump. */
272 if (can_throw_internal (insn
))
275 switch (GET_CODE (insn
))
289 /* OK unless it contains a delay slot or is an `asm' insn of some type.
290 We don't know anything about these. */
291 return (GET_CODE (PATTERN (insn
)) == SEQUENCE
292 || GET_CODE (PATTERN (insn
)) == ASM_INPUT
293 || asm_noperands (PATTERN (insn
)) >= 0);
300 /* Return TRUE if any resources are marked in both RES1 and RES2 or if either
301 resource set contains a volatile memory reference. Otherwise, return FALSE. */
304 resource_conflicts_p (struct resources
*res1
, struct resources
*res2
)
306 if ((res1
->cc
&& res2
->cc
) || (res1
->memory
&& res2
->memory
)
307 || res1
->volatil
|| res2
->volatil
)
310 return hard_reg_set_intersect_p (res1
->regs
, res2
->regs
);
313 /* Return TRUE if any resource marked in RES, a `struct resources', is
314 referenced by INSN. If INCLUDE_DELAYED_EFFECTS is set, return if the called
315 routine is using those resources.
317 We compute this by computing all the resources referenced by INSN and
318 seeing if this conflicts with RES. It might be faster to directly check
319 ourselves, and this is the way it used to work, but it means duplicating
320 a large block of complex code. */
323 insn_references_resource_p (rtx insn
, struct resources
*res
,
324 bool include_delayed_effects
)
326 struct resources insn_res
;
328 CLEAR_RESOURCE (&insn_res
);
329 mark_referenced_resources (insn
, &insn_res
, include_delayed_effects
);
330 return resource_conflicts_p (&insn_res
, res
);
333 /* Return TRUE if INSN modifies resources that are marked in RES.
334 INCLUDE_DELAYED_EFFECTS is set if the actions of that routine should be
335 included. CC0 is only modified if it is explicitly set; see comments
336 in front of mark_set_resources for details. */
339 insn_sets_resource_p (rtx insn
, struct resources
*res
,
340 bool include_delayed_effects
)
342 struct resources insn_sets
;
344 CLEAR_RESOURCE (&insn_sets
);
345 mark_set_resources (insn
, &insn_sets
, 0,
346 (include_delayed_effects
349 return resource_conflicts_p (&insn_sets
, res
);
352 /* Find a label at the end of the function or before a RETURN. If there
353 is none, try to make one. If that fails, returns 0.
355 The property of such a label is that it is placed just before the
356 epilogue or a bare RETURN insn, so that another bare RETURN can be
357 turned into a jump to the label unconditionally. In particular, the
358 label cannot be placed before a RETURN insn with a filled delay slot.
360 ??? There may be a problem with the current implementation. Suppose
361 we start with a bare RETURN insn and call find_end_label. It may set
362 function_return_label just before the RETURN. Suppose the machinery
363 is able to fill the delay slot of the RETURN insn afterwards. Then
364 function_return_label is no longer valid according to the property
365 described above and find_end_label will still return it unmodified.
366 Note that this is probably mitigated by the following observation:
367 once function_return_label is made, it is very likely the target of
368 a jump, so filling the delay slot of the RETURN will be much more
370 KIND is either simple_return_rtx or ret_rtx, indicating which type of
371 return we're looking for. */
373 static rtx_code_label
*
374 find_end_label (rtx kind
)
377 rtx_code_label
**plabel
;
380 plabel
= &function_return_label
;
383 gcc_assert (kind
== simple_return_rtx
);
384 plabel
= &function_simple_return_label
;
387 /* If we found one previously, return it. */
391 /* Otherwise, see if there is a label at the end of the function. If there
392 is, it must be that RETURN insns aren't needed, so that is our return
393 label and we don't have to do anything else. */
395 insn
= get_last_insn ();
397 || (NONJUMP_INSN_P (insn
)
398 && (GET_CODE (PATTERN (insn
)) == USE
399 || GET_CODE (PATTERN (insn
)) == CLOBBER
)))
400 insn
= PREV_INSN (insn
);
402 /* When a target threads its epilogue we might already have a
403 suitable return insn. If so put a label before it for the
404 function_return_label. */
406 && JUMP_P (PREV_INSN (insn
))
407 && PATTERN (PREV_INSN (insn
)) == kind
)
409 rtx_insn
*temp
= PREV_INSN (PREV_INSN (insn
));
410 rtx_code_label
*label
= gen_label_rtx ();
411 LABEL_NUSES (label
) = 0;
413 /* Put the label before any USE insns that may precede the RETURN
415 while (GET_CODE (temp
) == USE
)
416 temp
= PREV_INSN (temp
);
418 emit_label_after (label
, temp
);
422 else if (LABEL_P (insn
))
423 *plabel
= as_a
<rtx_code_label
*> (insn
);
426 rtx_code_label
*label
= gen_label_rtx ();
427 LABEL_NUSES (label
) = 0;
428 /* If the basic block reorder pass moves the return insn to
429 some other place try to locate it again and put our
430 function_return_label there. */
431 while (insn
&& ! (JUMP_P (insn
) && (PATTERN (insn
) == kind
)))
432 insn
= PREV_INSN (insn
);
435 insn
= PREV_INSN (insn
);
437 /* Put the label before any USE insns that may precede the
439 while (GET_CODE (insn
) == USE
)
440 insn
= PREV_INSN (insn
);
442 emit_label_after (label
, insn
);
446 if (targetm
.have_epilogue () && ! targetm
.have_return ())
447 /* The RETURN insn has its delay slot filled so we cannot
448 emit the label just before it. Since we already have
449 an epilogue and cannot emit a new RETURN, we cannot
450 emit the label at all. */
453 /* Otherwise, make a new label and emit a RETURN and BARRIER,
456 if (targetm
.have_return ())
458 /* The return we make may have delay slots too. */
459 rtx_insn
*pat
= targetm
.gen_return ();
460 rtx_insn
*insn
= emit_jump_insn (pat
);
461 set_return_jump_label (insn
);
463 if (num_delay_slots (insn
) > 0)
464 obstack_ptr_grow (&unfilled_slots_obstack
, insn
);
470 /* Show one additional use for this label so it won't go away until
472 ++LABEL_NUSES (*plabel
);
477 /* Put INSN and LIST together in a SEQUENCE rtx of LENGTH, and replace
478 the pattern of INSN with the SEQUENCE.
480 Returns the insn containing the SEQUENCE that replaces INSN. */
483 emit_delay_sequence (rtx_insn
*insn
, const vec
<rtx_insn
*> &list
, int length
)
485 /* Allocate the rtvec to hold the insns and the SEQUENCE. */
486 rtvec seqv
= rtvec_alloc (length
+ 1);
487 rtx seq
= gen_rtx_SEQUENCE (VOIDmode
, seqv
);
488 rtx_insn
*seq_insn
= make_insn_raw (seq
);
490 /* If DELAY_INSN has a location, use it for SEQ_INSN. If DELAY_INSN does
491 not have a location, but one of the delayed insns does, we pick up a
492 location from there later. */
493 INSN_LOCATION (seq_insn
) = INSN_LOCATION (insn
);
495 /* Unlink INSN from the insn chain, so that we can put it into
496 the SEQUENCE. Remember where we want to emit SEQUENCE in AFTER. */
497 rtx_insn
*after
= PREV_INSN (insn
);
499 SET_NEXT_INSN (insn
) = SET_PREV_INSN (insn
) = NULL
;
501 /* Build our SEQUENCE and rebuild the insn chain. */
503 XVECEXP (seq
, 0, 0) = emit_insn (insn
);
505 unsigned int delay_insns
= list
.length ();
506 gcc_assert (delay_insns
== (unsigned int) length
);
507 for (unsigned int i
= 0; i
< delay_insns
; i
++)
509 rtx_insn
*tem
= list
[i
];
512 /* Show that this copy of the insn isn't deleted. */
513 tem
->set_undeleted ();
515 /* Unlink insn from its original place, and re-emit it into
517 SET_NEXT_INSN (tem
) = SET_PREV_INSN (tem
) = NULL
;
518 XVECEXP (seq
, 0, i
+ 1) = emit_insn (tem
);
520 /* SPARC assembler, for instance, emit warning when debug info is output
521 into the delay slot. */
522 if (INSN_LOCATION (tem
) && !INSN_LOCATION (seq_insn
))
523 INSN_LOCATION (seq_insn
) = INSN_LOCATION (tem
);
524 INSN_LOCATION (tem
) = 0;
526 for (note
= REG_NOTES (tem
); note
; note
= next
)
528 next
= XEXP (note
, 1);
529 switch (REG_NOTE_KIND (note
))
532 /* Remove any REG_DEAD notes because we can't rely on them now
533 that the insn has been moved. */
534 remove_note (tem
, note
);
537 case REG_LABEL_OPERAND
:
538 case REG_LABEL_TARGET
:
539 /* Keep the label reference count up to date. */
540 if (LABEL_P (XEXP (note
, 0)))
541 LABEL_NUSES (XEXP (note
, 0)) ++;
551 /* Splice our SEQUENCE into the insn stream where INSN used to be. */
552 add_insn_after (seq_insn
, after
, NULL
);
557 /* Add INSN to DELAY_LIST and return the head of the new list. The list must
558 be in the order in which the insns are to be executed. */
561 add_to_delay_list (rtx_insn
*insn
, vec
<rtx_insn
*> *delay_list
)
563 /* If INSN has its block number recorded, clear it since we may
564 be moving the insn to a new block. */
565 clear_hashed_info_for_insn (insn
);
566 delay_list
->safe_push (insn
);
569 /* Delete INSN from the delay slot of the insn that it is in, which may
570 produce an insn with no delay slots. Return the new insn. */
573 delete_from_delay_slot (rtx_insn
*insn
)
575 rtx_insn
*trial
, *seq_insn
, *prev
;
580 /* We first must find the insn containing the SEQUENCE with INSN in its
581 delay slot. Do this by finding an insn, TRIAL, where
582 PREV_INSN (NEXT_INSN (TRIAL)) != TRIAL. */
585 PREV_INSN (NEXT_INSN (trial
)) == trial
;
586 trial
= NEXT_INSN (trial
))
589 seq_insn
= PREV_INSN (NEXT_INSN (trial
));
590 seq
= as_a
<rtx_sequence
*> (PATTERN (seq_insn
));
592 if (NEXT_INSN (seq_insn
) && BARRIER_P (NEXT_INSN (seq_insn
)))
595 /* Create a delay list consisting of all the insns other than the one
596 we are deleting (unless we were the only one). */
597 auto_vec
<rtx_insn
*, 5> delay_list
;
599 for (i
= 1; i
< seq
->len (); i
++)
600 if (seq
->insn (i
) != insn
)
601 add_to_delay_list (seq
->insn (i
), &delay_list
);
603 /* Delete the old SEQUENCE, re-emit the insn that used to have the delay
604 list, and rebuild the delay list if non-empty. */
605 prev
= PREV_INSN (seq_insn
);
606 trial
= seq
->insn (0);
607 delete_related_insns (seq_insn
);
608 add_insn_after (trial
, prev
, NULL
);
610 /* If there was a barrier after the old SEQUENCE, remit it. */
612 emit_barrier_after (trial
);
614 /* If there are any delay insns, remit them. Otherwise clear the
616 if (!delay_list
.is_empty ())
617 trial
= emit_delay_sequence (trial
, delay_list
, XVECLEN (seq
, 0) - 2);
618 else if (JUMP_P (trial
))
619 INSN_ANNULLED_BRANCH_P (trial
) = 0;
621 INSN_FROM_TARGET_P (insn
) = 0;
623 /* Show we need to fill this insn again. */
624 obstack_ptr_grow (&unfilled_slots_obstack
, trial
);
629 /* Delete INSN, a JUMP_INSN. If it is a conditional jump, we must track down
630 the insn that sets CC0 for it and delete it too. */
633 delete_scheduled_jump (rtx_insn
*insn
)
635 /* Delete the insn that sets cc0 for us. On machines without cc0, we could
636 delete the insn that sets the condition code, but it is hard to find it.
637 Since this case is rare anyway, don't bother trying; there would likely
638 be other insns that became dead anyway, which we wouldn't know to
641 if (HAVE_cc0
&& reg_mentioned_p (cc0_rtx
, insn
))
643 rtx note
= find_reg_note (insn
, REG_CC_SETTER
, NULL_RTX
);
645 /* If a reg-note was found, it points to an insn to set CC0. This
646 insn is in the delay list of some other insn. So delete it from
647 the delay list it was in. */
650 if (! FIND_REG_INC_NOTE (XEXP (note
, 0), NULL_RTX
)
651 && sets_cc0_p (PATTERN (XEXP (note
, 0))) == 1)
652 delete_from_delay_slot (as_a
<rtx_insn
*> (XEXP (note
, 0)));
656 /* The insn setting CC0 is our previous insn, but it may be in
657 a delay slot. It will be the last insn in the delay slot, if
659 rtx_insn
*trial
= previous_insn (insn
);
661 trial
= prev_nonnote_insn (trial
);
662 if (sets_cc0_p (PATTERN (trial
)) != 1
663 || FIND_REG_INC_NOTE (trial
, NULL_RTX
))
665 if (PREV_INSN (NEXT_INSN (trial
)) == trial
)
666 delete_related_insns (trial
);
668 delete_from_delay_slot (trial
);
672 delete_related_insns (insn
);
675 /* Counters for delay-slot filling. */
677 #define NUM_REORG_FUNCTIONS 2
678 #define MAX_DELAY_HISTOGRAM 3
679 #define MAX_REORG_PASSES 2
681 static int num_insns_needing_delays
[NUM_REORG_FUNCTIONS
][MAX_REORG_PASSES
];
683 static int num_filled_delays
[NUM_REORG_FUNCTIONS
][MAX_DELAY_HISTOGRAM
+1][MAX_REORG_PASSES
];
685 static int reorg_pass_number
;
688 note_delay_statistics (int slots_filled
, int index
)
690 num_insns_needing_delays
[index
][reorg_pass_number
]++;
691 if (slots_filled
> MAX_DELAY_HISTOGRAM
)
692 slots_filled
= MAX_DELAY_HISTOGRAM
;
693 num_filled_delays
[index
][slots_filled
][reorg_pass_number
]++;
696 /* Optimize the following cases:
698 1. When a conditional branch skips over only one instruction,
699 use an annulling branch and put that insn in the delay slot.
700 Use either a branch that annuls when the condition if true or
701 invert the test with a branch that annuls when the condition is
702 false. This saves insns, since otherwise we must copy an insn
705 (orig) (skip) (otherwise)
706 Bcc.n L1 Bcc',a L1 Bcc,a L1'
713 2. When a conditional branch skips over only one instruction,
714 and after that, it unconditionally branches somewhere else,
715 perform the similar optimization. This saves executing the
716 second branch in the case where the inverted condition is true.
725 This should be expanded to skip over N insns, where N is the number
726 of delay slots required. */
729 optimize_skip (rtx_jump_insn
*insn
, vec
<rtx_insn
*> *delay_list
)
731 rtx_insn
*trial
= next_nonnote_insn (insn
);
732 rtx_insn
*next_trial
= next_active_insn (trial
);
735 flags
= get_jump_flags (insn
, JUMP_LABEL (insn
));
738 || !NONJUMP_INSN_P (trial
)
739 || GET_CODE (PATTERN (trial
)) == SEQUENCE
740 || recog_memoized (trial
) < 0
741 || (! eligible_for_annul_false (insn
, 0, trial
, flags
)
742 && ! eligible_for_annul_true (insn
, 0, trial
, flags
))
743 || RTX_FRAME_RELATED_P (trial
)
744 || can_throw_internal (trial
))
747 /* There are two cases where we are just executing one insn (we assume
748 here that a branch requires only one insn; this should be generalized
749 at some point): Where the branch goes around a single insn or where
750 we have one insn followed by a branch to the same label we branch to.
751 In both of these cases, inverting the jump and annulling the delay
752 slot give the same effect in fewer insns. */
753 if (next_trial
== next_active_insn (JUMP_LABEL_AS_INSN (insn
))
755 && simplejump_or_return_p (next_trial
)
756 && JUMP_LABEL (insn
) == JUMP_LABEL (next_trial
)))
758 if (eligible_for_annul_false (insn
, 0, trial
, flags
))
760 if (invert_jump (insn
, JUMP_LABEL (insn
), 1))
761 INSN_FROM_TARGET_P (trial
) = 1;
762 else if (! eligible_for_annul_true (insn
, 0, trial
, flags
))
766 add_to_delay_list (trial
, delay_list
);
767 next_trial
= next_active_insn (trial
);
768 update_block (trial
, trial
);
769 delete_related_insns (trial
);
771 /* Also, if we are targeting an unconditional
772 branch, thread our jump to the target of that branch. Don't
773 change this into a RETURN here, because it may not accept what
774 we have in the delay slot. We'll fix this up later. */
775 if (next_trial
&& simplejump_or_return_p (next_trial
))
777 rtx target_label
= JUMP_LABEL (next_trial
);
778 if (ANY_RETURN_P (target_label
))
779 target_label
= find_end_label (target_label
);
783 /* Recompute the flags based on TARGET_LABEL since threading
784 the jump to TARGET_LABEL may change the direction of the
785 jump (which may change the circumstances in which the
786 delay slot is nullified). */
787 flags
= get_jump_flags (insn
, target_label
);
788 if (eligible_for_annul_true (insn
, 0, trial
, flags
))
789 reorg_redirect_jump (insn
, target_label
);
793 INSN_ANNULLED_BRANCH_P (insn
) = 1;
797 /* Encode and return branch direction and prediction information for
798 INSN assuming it will jump to LABEL.
800 Non conditional branches return no direction information and
801 are predicted as very likely taken. */
804 get_jump_flags (const rtx_insn
*insn
, rtx label
)
808 /* get_jump_flags can be passed any insn with delay slots, these may
809 be INSNs, CALL_INSNs, or JUMP_INSNs. Only JUMP_INSNs have branch
810 direction information, and only if they are conditional jumps.
812 If LABEL is a return, then there is no way to determine the branch
815 && (condjump_p (insn
) || condjump_in_parallel_p (insn
))
816 && !ANY_RETURN_P (label
)
817 && INSN_UID (insn
) <= max_uid
818 && INSN_UID (label
) <= max_uid
)
820 = (uid_to_ruid
[INSN_UID (label
)] > uid_to_ruid
[INSN_UID (insn
)])
821 ? ATTR_FLAG_forward
: ATTR_FLAG_backward
;
822 /* No valid direction information. */
829 /* Return truth value of the statement that this branch
830 is mostly taken. If we think that the branch is extremely likely
831 to be taken, we return 2. If the branch is slightly more likely to be
832 taken, return 1. If the branch is slightly less likely to be taken,
833 return 0 and if the branch is highly unlikely to be taken, return -1. */
836 mostly_true_jump (rtx jump_insn
)
838 /* If branch probabilities are available, then use that number since it
839 always gives a correct answer. */
840 rtx note
= find_reg_note (jump_insn
, REG_BR_PROB
, 0);
843 int prob
= XINT (note
, 0);
845 if (prob
>= REG_BR_PROB_BASE
* 9 / 10)
847 else if (prob
>= REG_BR_PROB_BASE
/ 2)
849 else if (prob
>= REG_BR_PROB_BASE
/ 10)
855 /* If there is no note, assume branches are not taken.
856 This should be rare. */
860 /* Return the condition under which INSN will branch to TARGET. If TARGET
861 is zero, return the condition under which INSN will return. If INSN is
862 an unconditional branch, return const_true_rtx. If INSN isn't a simple
863 type of jump, or it doesn't go to TARGET, return 0. */
866 get_branch_condition (const rtx_insn
*insn
, rtx target
)
868 rtx pat
= PATTERN (insn
);
871 if (condjump_in_parallel_p (insn
))
872 pat
= XVECEXP (pat
, 0, 0);
874 if (ANY_RETURN_P (pat
) && pat
== target
)
875 return const_true_rtx
;
877 if (GET_CODE (pat
) != SET
|| SET_DEST (pat
) != pc_rtx
)
881 if (GET_CODE (src
) == LABEL_REF
&& label_ref_label (src
) == target
)
882 return const_true_rtx
;
884 else if (GET_CODE (src
) == IF_THEN_ELSE
885 && XEXP (src
, 2) == pc_rtx
886 && ((GET_CODE (XEXP (src
, 1)) == LABEL_REF
887 && label_ref_label (XEXP (src
, 1)) == target
)
888 || (ANY_RETURN_P (XEXP (src
, 1)) && XEXP (src
, 1) == target
)))
889 return XEXP (src
, 0);
891 else if (GET_CODE (src
) == IF_THEN_ELSE
892 && XEXP (src
, 1) == pc_rtx
893 && ((GET_CODE (XEXP (src
, 2)) == LABEL_REF
894 && label_ref_label (XEXP (src
, 2)) == target
)
895 || (ANY_RETURN_P (XEXP (src
, 2)) && XEXP (src
, 2) == target
)))
898 rev
= reversed_comparison_code (XEXP (src
, 0), insn
);
900 return gen_rtx_fmt_ee (rev
, GET_MODE (XEXP (src
, 0)),
901 XEXP (XEXP (src
, 0), 0),
902 XEXP (XEXP (src
, 0), 1));
908 /* Return nonzero if CONDITION is more strict than the condition of
909 INSN, i.e., if INSN will always branch if CONDITION is true. */
912 condition_dominates_p (rtx condition
, const rtx_insn
*insn
)
914 rtx other_condition
= get_branch_condition (insn
, JUMP_LABEL (insn
));
915 enum rtx_code code
= GET_CODE (condition
);
916 enum rtx_code other_code
;
918 if (rtx_equal_p (condition
, other_condition
)
919 || other_condition
== const_true_rtx
)
922 else if (condition
== const_true_rtx
|| other_condition
== 0)
925 other_code
= GET_CODE (other_condition
);
926 if (GET_RTX_LENGTH (code
) != 2 || GET_RTX_LENGTH (other_code
) != 2
927 || ! rtx_equal_p (XEXP (condition
, 0), XEXP (other_condition
, 0))
928 || ! rtx_equal_p (XEXP (condition
, 1), XEXP (other_condition
, 1)))
931 return comparison_dominates_p (code
, other_code
);
934 /* Return nonzero if redirecting JUMP to NEWLABEL does not invalidate
935 any insns already in the delay slot of JUMP. */
938 redirect_with_delay_slots_safe_p (rtx_insn
*jump
, rtx newlabel
, rtx seq
)
941 rtx_sequence
*pat
= as_a
<rtx_sequence
*> (PATTERN (seq
));
943 /* Make sure all the delay slots of this jump would still
944 be valid after threading the jump. If they are still
945 valid, then return nonzero. */
947 flags
= get_jump_flags (jump
, newlabel
);
948 for (i
= 1; i
< pat
->len (); i
++)
950 #if ANNUL_IFFALSE_SLOTS
951 (INSN_ANNULLED_BRANCH_P (jump
)
952 && INSN_FROM_TARGET_P (pat
->insn (i
)))
953 ? eligible_for_annul_false (jump
, i
- 1, pat
->insn (i
), flags
) :
955 #if ANNUL_IFTRUE_SLOTS
956 (INSN_ANNULLED_BRANCH_P (jump
)
957 && ! INSN_FROM_TARGET_P (XVECEXP (pat
, 0, i
)))
958 ? eligible_for_annul_true (jump
, i
- 1, pat
->insn (i
), flags
) :
960 eligible_for_delay (jump
, i
- 1, pat
->insn (i
), flags
)))
963 return (i
== pat
->len ());
966 /* Return nonzero if redirecting JUMP to NEWLABEL does not invalidate
967 any insns we wish to place in the delay slot of JUMP. */
970 redirect_with_delay_list_safe_p (rtx_insn
*jump
, rtx newlabel
,
971 const vec
<rtx_insn
*> &delay_list
)
973 /* Make sure all the insns in DELAY_LIST would still be
974 valid after threading the jump. If they are still
975 valid, then return nonzero. */
977 int flags
= get_jump_flags (jump
, newlabel
);
978 unsigned int delay_insns
= delay_list
.length ();
980 for (; i
< delay_insns
; i
++)
982 #if ANNUL_IFFALSE_SLOTS
983 (INSN_ANNULLED_BRANCH_P (jump
)
984 && INSN_FROM_TARGET_P (delay_list
[i
]))
985 ? eligible_for_annul_false (jump
, i
, delay_list
[i
], flags
) :
987 #if ANNUL_IFTRUE_SLOTS
988 (INSN_ANNULLED_BRANCH_P (jump
)
989 && ! INSN_FROM_TARGET_P (delay_list
[i
]))
990 ? eligible_for_annul_true (jump
, i
, delay_list
[i
], flags
) :
992 eligible_for_delay (jump
, i
, delay_list
[i
], flags
)))
995 return i
== delay_insns
;
998 /* DELAY_LIST is a list of insns that have already been placed into delay
999 slots. See if all of them have the same annulling status as ANNUL_TRUE_P.
1000 If not, return 0; otherwise return 1. */
1003 check_annul_list_true_false (int annul_true_p
,
1004 const vec
<rtx_insn
*> &delay_list
)
1008 FOR_EACH_VEC_ELT (delay_list
, i
, trial
)
1009 if ((annul_true_p
&& INSN_FROM_TARGET_P (trial
))
1010 || (!annul_true_p
&& !INSN_FROM_TARGET_P (trial
)))
1016 /* INSN branches to an insn whose pattern SEQ is a SEQUENCE. Given that
1017 the condition tested by INSN is CONDITION and the resources shown in
1018 OTHER_NEEDED are needed after INSN, see whether INSN can take all the insns
1019 from SEQ's delay list, in addition to whatever insns it may execute
1020 (in DELAY_LIST). SETS and NEEDED are denote resources already set and
1021 needed while searching for delay slot insns. Return the concatenated
1022 delay list if possible, otherwise, return 0.
1024 SLOTS_TO_FILL is the total number of slots required by INSN, and
1025 PSLOTS_FILLED points to the number filled so far (also the number of
1026 insns in DELAY_LIST). It is updated with the number that have been
1027 filled from the SEQUENCE, if any.
1029 PANNUL_P points to a nonzero value if we already know that we need
1030 to annul INSN. If this routine determines that annulling is needed,
1031 it may set that value nonzero.
1033 PNEW_THREAD points to a location that is to receive the place at which
1034 execution should continue. */
1037 steal_delay_list_from_target (rtx_insn
*insn
, rtx condition
, rtx_sequence
*seq
,
1038 vec
<rtx_insn
*> *delay_list
, resources
*sets
,
1039 struct resources
*needed
,
1040 struct resources
*other_needed
,
1041 int slots_to_fill
, int *pslots_filled
,
1042 int *pannul_p
, rtx
*pnew_thread
)
1044 int slots_remaining
= slots_to_fill
- *pslots_filled
;
1045 int total_slots_filled
= *pslots_filled
;
1046 auto_vec
<rtx_insn
*, 5> new_delay_list
;
1047 int must_annul
= *pannul_p
;
1050 struct resources cc_set
;
1053 /* We can't do anything if there are more delay slots in SEQ than we
1054 can handle, or if we don't know that it will be a taken branch.
1055 We know that it will be a taken branch if it is either an unconditional
1056 branch or a conditional branch with a stricter branch condition.
1058 Also, exit if the branch has more than one set, since then it is computing
1059 other results that can't be ignored, e.g. the HPPA mov&branch instruction.
1060 ??? It may be possible to move other sets into INSN in addition to
1061 moving the instructions in the delay slots.
1063 We can not steal the delay list if one of the instructions in the
1064 current delay_list modifies the condition codes and the jump in the
1065 sequence is a conditional jump. We can not do this because we can
1066 not change the direction of the jump because the condition codes
1067 will effect the direction of the jump in the sequence. */
1069 CLEAR_RESOURCE (&cc_set
);
1072 FOR_EACH_VEC_ELT (*delay_list
, i
, trial
)
1074 mark_set_resources (trial
, &cc_set
, 0, MARK_SRC_DEST_CALL
);
1075 if (insn_references_resource_p (seq
->insn (0), &cc_set
, false))
1079 if (XVECLEN (seq
, 0) - 1 > slots_remaining
1080 || ! condition_dominates_p (condition
, seq
->insn (0))
1081 || ! single_set (seq
->insn (0)))
1084 /* On some targets, branches with delay slots can have a limited
1085 displacement. Give the back end a chance to tell us we can't do
1087 if (! targetm
.can_follow_jump (insn
, seq
->insn (0)))
1090 redundant
= XALLOCAVEC (bool, XVECLEN (seq
, 0));
1091 for (i
= 1; i
< seq
->len (); i
++)
1093 rtx_insn
*trial
= seq
->insn (i
);
1096 if (insn_references_resource_p (trial
, sets
, false)
1097 || insn_sets_resource_p (trial
, needed
, false)
1098 || insn_sets_resource_p (trial
, sets
, false)
1099 /* If TRIAL sets CC0, we can't copy it, so we can't steal this
1101 || (HAVE_cc0
&& find_reg_note (trial
, REG_CC_USER
, NULL_RTX
))
1102 /* If TRIAL is from the fallthrough code of an annulled branch insn
1103 in SEQ, we cannot use it. */
1104 || (INSN_ANNULLED_BRANCH_P (seq
->insn (0))
1105 && ! INSN_FROM_TARGET_P (trial
)))
1108 /* If this insn was already done (usually in a previous delay slot),
1109 pretend we put it in our delay slot. */
1110 redundant
[i
] = redundant_insn (trial
, insn
, new_delay_list
);
1114 /* We will end up re-vectoring this branch, so compute flags
1115 based on jumping to the new label. */
1116 flags
= get_jump_flags (insn
, JUMP_LABEL (seq
->insn (0)));
1119 && ((condition
== const_true_rtx
1120 || (! insn_sets_resource_p (trial
, other_needed
, false)
1121 && ! may_trap_or_fault_p (PATTERN (trial
)))))
1122 ? eligible_for_delay (insn
, total_slots_filled
, trial
, flags
)
1123 : (must_annul
|| (delay_list
->is_empty () && new_delay_list
.is_empty ()))
1125 check_annul_list_true_false (0, *delay_list
)
1126 && check_annul_list_true_false (0, new_delay_list
)
1127 && eligible_for_annul_false (insn
, total_slots_filled
,
1132 /* Frame related instructions cannot go into annulled delay
1133 slots, it messes up the dwarf info. */
1134 if (RTX_FRAME_RELATED_P (trial
))
1138 rtx_insn
*temp
= copy_delay_slot_insn (trial
);
1139 INSN_FROM_TARGET_P (temp
) = 1;
1140 add_to_delay_list (temp
, &new_delay_list
);
1141 total_slots_filled
++;
1143 if (--slots_remaining
== 0)
1150 /* Record the effect of the instructions that were redundant and which
1151 we therefore decided not to copy. */
1152 for (i
= 1; i
< seq
->len (); i
++)
1154 update_block (seq
->insn (i
), insn
);
1156 /* Show the place to which we will be branching. */
1157 *pnew_thread
= first_active_target_insn (JUMP_LABEL (seq
->insn (0)));
1159 /* Add any new insns to the delay list and update the count of the
1160 number of slots filled. */
1161 *pslots_filled
= total_slots_filled
;
1166 FOR_EACH_VEC_ELT (new_delay_list
, i
, temp
)
1167 add_to_delay_list (temp
, delay_list
);
1170 /* Similar to steal_delay_list_from_target except that SEQ is on the
1171 fallthrough path of INSN. Here we only do something if the delay insn
1172 of SEQ is an unconditional branch. In that case we steal its delay slot
1173 for INSN since unconditional branches are much easier to fill. */
1176 steal_delay_list_from_fallthrough (rtx_insn
*insn
, rtx condition
,
1178 vec
<rtx_insn
*> *delay_list
,
1179 struct resources
*sets
,
1180 struct resources
*needed
,
1181 struct resources
*other_needed
,
1182 int slots_to_fill
, int *pslots_filled
,
1187 int must_annul
= *pannul_p
;
1190 flags
= get_jump_flags (insn
, JUMP_LABEL (insn
));
1192 /* We can't do anything if SEQ's delay insn isn't an
1193 unconditional branch. */
1195 if (! simplejump_or_return_p (seq
->insn (0)))
1198 for (i
= 1; i
< seq
->len (); i
++)
1200 rtx_insn
*trial
= seq
->insn (i
);
1202 /* If TRIAL sets CC0, stealing it will move it too far from the use
1204 if (insn_references_resource_p (trial
, sets
, false)
1205 || insn_sets_resource_p (trial
, needed
, false)
1206 || insn_sets_resource_p (trial
, sets
, false)
1207 || (HAVE_cc0
&& sets_cc0_p (PATTERN (trial
))))
1211 /* If this insn was already done, we don't need it. */
1212 if (redundant_insn (trial
, insn
, *delay_list
))
1214 update_block (trial
, insn
);
1215 delete_from_delay_slot (trial
);
1220 && ((condition
== const_true_rtx
1221 || (! insn_sets_resource_p (trial
, other_needed
, false)
1222 && ! may_trap_or_fault_p (PATTERN (trial
)))))
1223 ? eligible_for_delay (insn
, *pslots_filled
, trial
, flags
)
1224 : (must_annul
|| delay_list
->is_empty ()) && (must_annul
= 1,
1225 check_annul_list_true_false (1, *delay_list
)
1226 && eligible_for_annul_true (insn
, *pslots_filled
, trial
, flags
)))
1230 delete_from_delay_slot (trial
);
1231 add_to_delay_list (trial
, delay_list
);
1233 if (++(*pslots_filled
) == slots_to_fill
)
1244 /* Try merging insns starting at THREAD which match exactly the insns in
1247 If all insns were matched and the insn was previously annulling, the
1248 annul bit will be cleared.
1250 For each insn that is merged, if the branch is or will be non-annulling,
1251 we delete the merged insn. */
1254 try_merge_delay_insns (rtx_insn
*insn
, rtx_insn
*thread
)
1256 rtx_insn
*trial
, *next_trial
;
1257 rtx_insn
*delay_insn
= as_a
<rtx_insn
*> (XVECEXP (PATTERN (insn
), 0, 0));
1258 int annul_p
= JUMP_P (delay_insn
) && INSN_ANNULLED_BRANCH_P (delay_insn
);
1259 int slot_number
= 1;
1260 int num_slots
= XVECLEN (PATTERN (insn
), 0);
1261 rtx next_to_match
= XVECEXP (PATTERN (insn
), 0, slot_number
);
1262 struct resources set
, needed
, modified
;
1263 auto_vec
<std::pair
<rtx_insn
*, bool>, 10> merged_insns
;
1266 flags
= get_jump_flags (delay_insn
, JUMP_LABEL (delay_insn
));
1268 CLEAR_RESOURCE (&needed
);
1269 CLEAR_RESOURCE (&set
);
1271 /* If this is not an annulling branch, take into account anything needed in
1272 INSN's delay slot. This prevents two increments from being incorrectly
1273 folded into one. If we are annulling, this would be the correct
1274 thing to do. (The alternative, looking at things set in NEXT_TO_MATCH
1275 will essentially disable this optimization. This method is somewhat of
1276 a kludge, but I don't see a better way.) */
1278 for (int i
= 1; i
< num_slots
; i
++)
1279 if (XVECEXP (PATTERN (insn
), 0, i
))
1280 mark_referenced_resources (XVECEXP (PATTERN (insn
), 0, i
), &needed
,
1283 for (trial
= thread
; !stop_search_p (trial
, 1); trial
= next_trial
)
1285 rtx pat
= PATTERN (trial
);
1286 rtx oldtrial
= trial
;
1288 next_trial
= next_nonnote_insn (trial
);
1290 /* TRIAL must be a CALL_INSN or INSN. Skip USE and CLOBBER. */
1291 if (NONJUMP_INSN_P (trial
)
1292 && (GET_CODE (pat
) == USE
|| GET_CODE (pat
) == CLOBBER
))
1295 if (GET_CODE (next_to_match
) == GET_CODE (trial
)
1296 /* We can't share an insn that sets cc0. */
1297 && (!HAVE_cc0
|| ! sets_cc0_p (pat
))
1298 && ! insn_references_resource_p (trial
, &set
, true)
1299 && ! insn_sets_resource_p (trial
, &set
, true)
1300 && ! insn_sets_resource_p (trial
, &needed
, true)
1301 && (trial
= try_split (pat
, trial
, 0)) != 0
1302 /* Update next_trial, in case try_split succeeded. */
1303 && (next_trial
= next_nonnote_insn (trial
))
1304 /* Likewise THREAD. */
1305 && (thread
= oldtrial
== thread
? trial
: thread
)
1306 && rtx_equal_p (PATTERN (next_to_match
), PATTERN (trial
))
1307 /* Have to test this condition if annul condition is different
1308 from (and less restrictive than) non-annulling one. */
1309 && eligible_for_delay (delay_insn
, slot_number
- 1, trial
, flags
))
1314 update_block (trial
, thread
);
1315 if (trial
== thread
)
1316 thread
= next_active_insn (thread
);
1318 delete_related_insns (trial
);
1319 INSN_FROM_TARGET_P (next_to_match
) = 0;
1322 merged_insns
.safe_push (std::pair
<rtx_insn
*, bool> (trial
, false));
1324 if (++slot_number
== num_slots
)
1327 next_to_match
= XVECEXP (PATTERN (insn
), 0, slot_number
);
1330 mark_set_resources (trial
, &set
, 0, MARK_SRC_DEST_CALL
);
1331 mark_referenced_resources (trial
, &needed
, true);
1334 /* See if we stopped on a filled insn. If we did, try to see if its
1335 delay slots match. */
1336 if (slot_number
!= num_slots
1337 && trial
&& NONJUMP_INSN_P (trial
)
1338 && GET_CODE (PATTERN (trial
)) == SEQUENCE
1339 && !(JUMP_P (XVECEXP (PATTERN (trial
), 0, 0))
1340 && INSN_ANNULLED_BRANCH_P (XVECEXP (PATTERN (trial
), 0, 0))))
1342 rtx_sequence
*pat
= as_a
<rtx_sequence
*> (PATTERN (trial
));
1343 rtx filled_insn
= XVECEXP (pat
, 0, 0);
1345 /* Account for resources set/needed by the filled insn. */
1346 mark_set_resources (filled_insn
, &set
, 0, MARK_SRC_DEST_CALL
);
1347 mark_referenced_resources (filled_insn
, &needed
, true);
1349 for (int i
= 1; i
< pat
->len (); i
++)
1351 rtx_insn
*dtrial
= pat
->insn (i
);
1353 CLEAR_RESOURCE (&modified
);
1354 /* Account for resources set by the insn following NEXT_TO_MATCH
1355 inside INSN's delay list. */
1356 for (int j
= 1; slot_number
+ j
< num_slots
; j
++)
1357 mark_set_resources (XVECEXP (PATTERN (insn
), 0, slot_number
+ j
),
1358 &modified
, 0, MARK_SRC_DEST_CALL
);
1359 /* Account for resources set by the insn before DTRIAL and inside
1360 TRIAL's delay list. */
1361 for (int j
= 1; j
< i
; j
++)
1362 mark_set_resources (XVECEXP (pat
, 0, j
),
1363 &modified
, 0, MARK_SRC_DEST_CALL
);
1364 if (! insn_references_resource_p (dtrial
, &set
, true)
1365 && ! insn_sets_resource_p (dtrial
, &set
, true)
1366 && ! insn_sets_resource_p (dtrial
, &needed
, true)
1367 && (!HAVE_cc0
|| ! sets_cc0_p (PATTERN (dtrial
)))
1368 && rtx_equal_p (PATTERN (next_to_match
), PATTERN (dtrial
))
1369 /* Check that DTRIAL and NEXT_TO_MATCH does not reference a
1370 resource modified between them (only dtrial is checked because
1371 next_to_match and dtrial shall to be equal in order to hit
1373 && ! insn_references_resource_p (dtrial
, &modified
, true)
1374 && eligible_for_delay (delay_insn
, slot_number
- 1, dtrial
, flags
))
1380 update_block (dtrial
, thread
);
1381 new_rtx
= delete_from_delay_slot (dtrial
);
1382 if (thread
->deleted ())
1384 INSN_FROM_TARGET_P (next_to_match
) = 0;
1387 merged_insns
.safe_push (std::pair
<rtx_insn
*, bool> (dtrial
,
1390 if (++slot_number
== num_slots
)
1393 next_to_match
= XVECEXP (PATTERN (insn
), 0, slot_number
);
1397 /* Keep track of the set/referenced resources for the delay
1398 slots of any trial insns we encounter. */
1399 mark_set_resources (dtrial
, &set
, 0, MARK_SRC_DEST_CALL
);
1400 mark_referenced_resources (dtrial
, &needed
, true);
1405 /* If all insns in the delay slot have been matched and we were previously
1406 annulling the branch, we need not any more. In that case delete all the
1407 merged insns. Also clear the INSN_FROM_TARGET_P bit of each insn in
1408 the delay list so that we know that it isn't only being used at the
1410 if (slot_number
== num_slots
&& annul_p
)
1412 unsigned int len
= merged_insns
.length ();
1413 for (unsigned int i
= len
- 1; i
< len
; i
--)
1414 if (merged_insns
[i
].second
)
1416 update_block (merged_insns
[i
].first
, thread
);
1417 rtx_insn
*new_rtx
= delete_from_delay_slot (merged_insns
[i
].first
);
1418 if (thread
->deleted ())
1423 update_block (merged_insns
[i
].first
, thread
);
1424 delete_related_insns (merged_insns
[i
].first
);
1427 INSN_ANNULLED_BRANCH_P (delay_insn
) = 0;
1429 for (int i
= 0; i
< XVECLEN (PATTERN (insn
), 0); i
++)
1430 INSN_FROM_TARGET_P (XVECEXP (PATTERN (insn
), 0, i
)) = 0;
1434 /* See if INSN is redundant with an insn in front of TARGET. Often this
1435 is called when INSN is a candidate for a delay slot of TARGET.
1436 DELAY_LIST are insns that will be placed in delay slots of TARGET in front
1437 of INSN. Often INSN will be redundant with an insn in a delay slot of
1438 some previous insn. This happens when we have a series of branches to the
1439 same label; in that case the first insn at the target might want to go
1440 into each of the delay slots.
1442 If we are not careful, this routine can take up a significant fraction
1443 of the total compilation time (4%), but only wins rarely. Hence we
1444 speed this routine up by making two passes. The first pass goes back
1445 until it hits a label and sees if it finds an insn with an identical
1446 pattern. Only in this (relatively rare) event does it check for
1449 We do not split insns we encounter. This could cause us not to find a
1450 redundant insn, but the cost of splitting seems greater than the possible
1451 gain in rare cases. */
1454 redundant_insn (rtx insn
, rtx_insn
*target
, const vec
<rtx_insn
*> &delay_list
)
1456 rtx target_main
= target
;
1457 rtx ipat
= PATTERN (insn
);
1460 struct resources needed
, set
;
1462 unsigned insns_to_search
;
1464 /* If INSN has any REG_UNUSED notes, it can't match anything since we
1465 are allowed to not actually assign to such a register. */
1466 if (find_reg_note (insn
, REG_UNUSED
, NULL_RTX
) != 0)
1469 /* Scan backwards looking for a match. */
1470 for (trial
= PREV_INSN (target
),
1471 insns_to_search
= MAX_DELAY_SLOT_INSN_SEARCH
;
1472 trial
&& insns_to_search
> 0;
1473 trial
= PREV_INSN (trial
))
1475 /* (use (insn))s can come immediately after a barrier if the
1476 label that used to precede them has been deleted as dead.
1477 See delete_related_insns. */
1478 if (LABEL_P (trial
) || BARRIER_P (trial
))
1481 if (!INSN_P (trial
))
1485 pat
= PATTERN (trial
);
1486 if (GET_CODE (pat
) == USE
|| GET_CODE (pat
) == CLOBBER
)
1489 if (rtx_sequence
*seq
= dyn_cast
<rtx_sequence
*> (pat
))
1491 /* Stop for a CALL and its delay slots because it is difficult to
1492 track its resource needs correctly. */
1493 if (CALL_P (seq
->element (0)))
1496 /* Stop for an INSN or JUMP_INSN with delayed effects and its delay
1497 slots because it is difficult to track its resource needs
1500 if (INSN_SETS_ARE_DELAYED (seq
->insn (0)))
1503 if (INSN_REFERENCES_ARE_DELAYED (seq
->insn (0)))
1506 /* See if any of the insns in the delay slot match, updating
1507 resource requirements as we go. */
1508 for (i
= seq
->len () - 1; i
> 0; i
--)
1509 if (GET_CODE (seq
->element (i
)) == GET_CODE (insn
)
1510 && rtx_equal_p (PATTERN (seq
->element (i
)), ipat
)
1511 && ! find_reg_note (seq
->element (i
), REG_UNUSED
, NULL_RTX
))
1514 /* If found a match, exit this loop early. */
1519 else if (GET_CODE (trial
) == GET_CODE (insn
) && rtx_equal_p (pat
, ipat
)
1520 && ! find_reg_note (trial
, REG_UNUSED
, NULL_RTX
))
1524 /* If we didn't find an insn that matches, return 0. */
1528 /* See what resources this insn sets and needs. If they overlap, or
1529 if this insn references CC0, it can't be redundant. */
1531 CLEAR_RESOURCE (&needed
);
1532 CLEAR_RESOURCE (&set
);
1533 mark_set_resources (insn
, &set
, 0, MARK_SRC_DEST_CALL
);
1534 mark_referenced_resources (insn
, &needed
, true);
1536 /* If TARGET is a SEQUENCE, get the main insn. */
1537 if (NONJUMP_INSN_P (target
) && GET_CODE (PATTERN (target
)) == SEQUENCE
)
1538 target_main
= XVECEXP (PATTERN (target
), 0, 0);
1540 if (resource_conflicts_p (&needed
, &set
)
1541 || (HAVE_cc0
&& reg_mentioned_p (cc0_rtx
, ipat
))
1542 /* The insn requiring the delay may not set anything needed or set by
1544 || insn_sets_resource_p (target_main
, &needed
, true)
1545 || insn_sets_resource_p (target_main
, &set
, true))
1548 /* Insns we pass may not set either NEEDED or SET, so merge them for
1550 needed
.memory
|= set
.memory
;
1551 IOR_HARD_REG_SET (needed
.regs
, set
.regs
);
1553 /* This insn isn't redundant if it conflicts with an insn that either is
1554 or will be in a delay slot of TARGET. */
1558 FOR_EACH_VEC_ELT (delay_list
, j
, temp
)
1559 if (insn_sets_resource_p (temp
, &needed
, true))
1562 if (NONJUMP_INSN_P (target
) && GET_CODE (PATTERN (target
)) == SEQUENCE
)
1563 for (i
= 1; i
< XVECLEN (PATTERN (target
), 0); i
++)
1564 if (insn_sets_resource_p (XVECEXP (PATTERN (target
), 0, i
), &needed
,
1568 /* Scan backwards until we reach a label or an insn that uses something
1569 INSN sets or sets something insn uses or sets. */
1571 for (trial
= PREV_INSN (target
),
1572 insns_to_search
= MAX_DELAY_SLOT_INSN_SEARCH
;
1573 trial
&& !LABEL_P (trial
) && insns_to_search
> 0;
1574 trial
= PREV_INSN (trial
))
1576 if (!INSN_P (trial
))
1580 pat
= PATTERN (trial
);
1581 if (GET_CODE (pat
) == USE
|| GET_CODE (pat
) == CLOBBER
)
1584 if (rtx_sequence
*seq
= dyn_cast
<rtx_sequence
*> (pat
))
1586 bool annul_p
= false;
1587 rtx_insn
*control
= seq
->insn (0);
1589 /* If this is a CALL_INSN and its delay slots, it is hard to track
1590 the resource needs properly, so give up. */
1591 if (CALL_P (control
))
1594 /* If this is an INSN or JUMP_INSN with delayed effects, it
1595 is hard to track the resource needs properly, so give up. */
1597 if (INSN_SETS_ARE_DELAYED (control
))
1600 if (INSN_REFERENCES_ARE_DELAYED (control
))
1603 if (JUMP_P (control
))
1604 annul_p
= INSN_ANNULLED_BRANCH_P (control
);
1606 /* See if any of the insns in the delay slot match, updating
1607 resource requirements as we go. */
1608 for (i
= seq
->len () - 1; i
> 0; i
--)
1610 rtx_insn
*candidate
= seq
->insn (i
);
1612 /* If an insn will be annulled if the branch is false, it isn't
1613 considered as a possible duplicate insn. */
1614 if (rtx_equal_p (PATTERN (candidate
), ipat
)
1615 && ! (annul_p
&& INSN_FROM_TARGET_P (candidate
)))
1617 /* Show that this insn will be used in the sequel. */
1618 INSN_FROM_TARGET_P (candidate
) = 0;
1622 /* Unless this is an annulled insn from the target of a branch,
1623 we must stop if it sets anything needed or set by INSN. */
1624 if ((!annul_p
|| !INSN_FROM_TARGET_P (candidate
))
1625 && insn_sets_resource_p (candidate
, &needed
, true))
1629 /* If the insn requiring the delay slot conflicts with INSN, we
1631 if (insn_sets_resource_p (control
, &needed
, true))
1636 /* See if TRIAL is the same as INSN. */
1637 pat
= PATTERN (trial
);
1638 if (rtx_equal_p (pat
, ipat
))
1641 /* Can't go any further if TRIAL conflicts with INSN. */
1642 if (insn_sets_resource_p (trial
, &needed
, true))
1650 /* Return 1 if THREAD can only be executed in one way. If LABEL is nonzero,
1651 it is the target of the branch insn being scanned. If ALLOW_FALLTHROUGH
1652 is nonzero, we are allowed to fall into this thread; otherwise, we are
1655 If LABEL is used more than one or we pass a label other than LABEL before
1656 finding an active insn, we do not own this thread. */
1659 own_thread_p (rtx thread
, rtx label
, int allow_fallthrough
)
1661 rtx_insn
*active_insn
;
1664 /* We don't own the function end. */
1665 if (thread
== 0 || ANY_RETURN_P (thread
))
1668 /* We have a non-NULL insn. */
1669 rtx_insn
*thread_insn
= as_a
<rtx_insn
*> (thread
);
1671 /* Get the first active insn, or THREAD_INSN, if it is an active insn. */
1672 active_insn
= next_active_insn (PREV_INSN (thread_insn
));
1674 for (insn
= thread_insn
; insn
!= active_insn
; insn
= NEXT_INSN (insn
))
1676 && (insn
!= label
|| LABEL_NUSES (insn
) != 1))
1679 if (allow_fallthrough
)
1682 /* Ensure that we reach a BARRIER before any insn or label. */
1683 for (insn
= prev_nonnote_insn (thread_insn
);
1684 insn
== 0 || !BARRIER_P (insn
);
1685 insn
= prev_nonnote_insn (insn
))
1688 || (NONJUMP_INSN_P (insn
)
1689 && GET_CODE (PATTERN (insn
)) != USE
1690 && GET_CODE (PATTERN (insn
)) != CLOBBER
))
1696 /* Called when INSN is being moved from a location near the target of a jump.
1697 We leave a marker of the form (use (INSN)) immediately in front
1698 of WHERE for mark_target_live_regs. These markers will be deleted when
1701 We used to try to update the live status of registers if WHERE is at
1702 the start of a basic block, but that can't work since we may remove a
1703 BARRIER in relax_delay_slots. */
1706 update_block (rtx_insn
*insn
, rtx where
)
1708 /* Ignore if this was in a delay slot and it came from the target of
1710 if (INSN_FROM_TARGET_P (insn
))
1713 emit_insn_before (gen_rtx_USE (VOIDmode
, insn
), where
);
1715 /* INSN might be making a value live in a block where it didn't use to
1716 be. So recompute liveness information for this block. */
1718 incr_ticks_for_insn (insn
);
1721 /* Similar to REDIRECT_JUMP except that we update the BB_TICKS entry for
1722 the basic block containing the jump. */
1725 reorg_redirect_jump (rtx_jump_insn
*jump
, rtx nlabel
)
1727 incr_ticks_for_insn (jump
);
1728 return redirect_jump (jump
, nlabel
, 1);
1731 /* Called when INSN is being moved forward into a delay slot of DELAYED_INSN.
1732 We check every instruction between INSN and DELAYED_INSN for REG_DEAD notes
1733 that reference values used in INSN. If we find one, then we move the
1734 REG_DEAD note to INSN.
1736 This is needed to handle the case where a later insn (after INSN) has a
1737 REG_DEAD note for a register used by INSN, and this later insn subsequently
1738 gets moved before a CODE_LABEL because it is a redundant insn. In this
1739 case, mark_target_live_regs may be confused into thinking the register
1740 is dead because it sees a REG_DEAD note immediately before a CODE_LABEL. */
1743 update_reg_dead_notes (rtx_insn
*insn
, rtx_insn
*delayed_insn
)
1748 for (p
= next_nonnote_insn (insn
); p
!= delayed_insn
;
1749 p
= next_nonnote_insn (p
))
1750 for (link
= REG_NOTES (p
); link
; link
= next
)
1752 next
= XEXP (link
, 1);
1754 if (REG_NOTE_KIND (link
) != REG_DEAD
1755 || !REG_P (XEXP (link
, 0)))
1758 if (reg_referenced_p (XEXP (link
, 0), PATTERN (insn
)))
1760 /* Move the REG_DEAD note from P to INSN. */
1761 remove_note (p
, link
);
1762 XEXP (link
, 1) = REG_NOTES (insn
);
1763 REG_NOTES (insn
) = link
;
1768 /* Called when an insn redundant with start_insn is deleted. If there
1769 is a REG_DEAD note for the target of start_insn between start_insn
1770 and stop_insn, then the REG_DEAD note needs to be deleted since the
1771 value no longer dies there.
1773 If the REG_DEAD note isn't deleted, then mark_target_live_regs may be
1774 confused into thinking the register is dead. */
1777 fix_reg_dead_note (rtx_insn
*start_insn
, rtx stop_insn
)
1782 for (p
= next_nonnote_insn (start_insn
); p
!= stop_insn
;
1783 p
= next_nonnote_insn (p
))
1784 for (link
= REG_NOTES (p
); link
; link
= next
)
1786 next
= XEXP (link
, 1);
1788 if (REG_NOTE_KIND (link
) != REG_DEAD
1789 || !REG_P (XEXP (link
, 0)))
1792 if (reg_set_p (XEXP (link
, 0), PATTERN (start_insn
)))
1794 remove_note (p
, link
);
1800 /* Delete any REG_UNUSED notes that exist on INSN but not on REDUNDANT_INSN.
1802 This handles the case of udivmodXi4 instructions which optimize their
1803 output depending on whether any REG_UNUSED notes are present.
1804 we must make sure that INSN calculates as many results as REDUNDANT_INSN
1808 update_reg_unused_notes (rtx insn
, rtx redundant_insn
)
1812 for (link
= REG_NOTES (insn
); link
; link
= next
)
1814 next
= XEXP (link
, 1);
1816 if (REG_NOTE_KIND (link
) != REG_UNUSED
1817 || !REG_P (XEXP (link
, 0)))
1820 if (! find_regno_note (redundant_insn
, REG_UNUSED
,
1821 REGNO (XEXP (link
, 0))))
1822 remove_note (insn
, link
);
1826 static vec
<rtx
> sibling_labels
;
1828 /* Return the label before INSN, or put a new label there. If SIBLING is
1829 non-zero, it is another label associated with the new label (if any),
1830 typically the former target of the jump that will be redirected to
1834 get_label_before (rtx_insn
*insn
, rtx sibling
)
1838 /* Find an existing label at this point
1839 or make a new one if there is none. */
1840 label
= prev_nonnote_insn (insn
);
1842 if (label
== 0 || !LABEL_P (label
))
1844 rtx_insn
*prev
= PREV_INSN (insn
);
1846 label
= gen_label_rtx ();
1847 emit_label_after (label
, prev
);
1848 LABEL_NUSES (label
) = 0;
1851 sibling_labels
.safe_push (label
);
1852 sibling_labels
.safe_push (sibling
);
1858 /* Scan a function looking for insns that need a delay slot and find insns to
1859 put into the delay slot.
1861 NON_JUMPS_P is nonzero if we are to only try to fill non-jump insns (such
1862 as calls). We do these first since we don't want jump insns (that are
1863 easier to fill) to get the only insns that could be used for non-jump insns.
1864 When it is zero, only try to fill JUMP_INSNs.
1866 When slots are filled in this manner, the insns (including the
1867 delay_insn) are put together in a SEQUENCE rtx. In this fashion,
1868 it is possible to tell whether a delay slot has really been filled
1869 or not. `final' knows how to deal with this, by communicating
1870 through FINAL_SEQUENCE. */
1873 fill_simple_delay_slots (int non_jumps_p
)
1875 rtx_insn
*insn
, *trial
, *next_trial
;
1878 int num_unfilled_slots
= unfilled_slots_next
- unfilled_slots_base
;
1879 struct resources needed
, set
;
1880 int slots_to_fill
, slots_filled
;
1881 auto_vec
<rtx_insn
*, 5> delay_list
;
1883 for (i
= 0; i
< num_unfilled_slots
; i
++)
1886 /* Get the next insn to fill. If it has already had any slots assigned,
1887 we can't do anything with it. Maybe we'll improve this later. */
1889 insn
= unfilled_slots_base
[i
];
1892 || (NONJUMP_INSN_P (insn
)
1893 && GET_CODE (PATTERN (insn
)) == SEQUENCE
)
1894 || (JUMP_P (insn
) && non_jumps_p
)
1895 || (!JUMP_P (insn
) && ! non_jumps_p
))
1898 /* It may have been that this insn used to need delay slots, but
1899 now doesn't; ignore in that case. This can happen, for example,
1900 on the HP PA RISC, where the number of delay slots depends on
1901 what insns are nearby. */
1902 slots_to_fill
= num_delay_slots (insn
);
1904 /* Some machine description have defined instructions to have
1905 delay slots only in certain circumstances which may depend on
1906 nearby insns (which change due to reorg's actions).
1908 For example, the PA port normally has delay slots for unconditional
1911 However, the PA port claims such jumps do not have a delay slot
1912 if they are immediate successors of certain CALL_INSNs. This
1913 allows the port to favor filling the delay slot of the call with
1914 the unconditional jump. */
1915 if (slots_to_fill
== 0)
1918 /* This insn needs, or can use, some delay slots. SLOTS_TO_FILL
1919 says how many. After initialization, first try optimizing
1922 nop add %o7,.-L1,%o7
1926 If this case applies, the delay slot of the call is filled with
1927 the unconditional jump. This is done first to avoid having the
1928 delay slot of the call filled in the backward scan. Also, since
1929 the unconditional jump is likely to also have a delay slot, that
1930 insn must exist when it is subsequently scanned.
1932 This is tried on each insn with delay slots as some machines
1933 have insns which perform calls, but are not represented as
1937 delay_list
.truncate (0);
1940 flags
= get_jump_flags (insn
, JUMP_LABEL (insn
));
1942 flags
= get_jump_flags (insn
, NULL_RTX
);
1944 if ((trial
= next_active_insn (insn
))
1946 && simplejump_p (trial
)
1947 && eligible_for_delay (insn
, slots_filled
, trial
, flags
)
1948 && no_labels_between_p (insn
, trial
)
1949 && ! can_throw_internal (trial
))
1953 add_to_delay_list (trial
, &delay_list
);
1955 /* TRIAL may have had its delay slot filled, then unfilled. When
1956 the delay slot is unfilled, TRIAL is placed back on the unfilled
1957 slots obstack. Unfortunately, it is placed on the end of the
1958 obstack, not in its original location. Therefore, we must search
1959 from entry i + 1 to the end of the unfilled slots obstack to
1960 try and find TRIAL. */
1961 tmp
= &unfilled_slots_base
[i
+ 1];
1962 while (*tmp
!= trial
&& tmp
!= unfilled_slots_next
)
1965 /* Remove the unconditional jump from consideration for delay slot
1966 filling and unthread it. */
1970 rtx_insn
*next
= NEXT_INSN (trial
);
1971 rtx_insn
*prev
= PREV_INSN (trial
);
1973 SET_NEXT_INSN (prev
) = next
;
1975 SET_PREV_INSN (next
) = prev
;
1979 /* Now, scan backwards from the insn to search for a potential
1980 delay-slot candidate. Stop searching when a label or jump is hit.
1982 For each candidate, if it is to go into the delay slot (moved
1983 forward in execution sequence), it must not need or set any resources
1984 that were set by later insns and must not set any resources that
1985 are needed for those insns.
1987 The delay slot insn itself sets resources unless it is a call
1988 (in which case the called routine, not the insn itself, is doing
1991 if (slots_filled
< slots_to_fill
)
1993 /* If the flags register is dead after the insn, then we want to be
1994 able to accept a candidate that clobbers it. For this purpose,
1995 we need to filter the flags register during life analysis, so
1996 that it doesn't create RAW and WAW dependencies, while still
1997 creating the necessary WAR dependencies. */
1999 = (slots_to_fill
== 1
2000 && targetm
.flags_regnum
!= INVALID_REGNUM
2001 && find_regno_note (insn
, REG_DEAD
, targetm
.flags_regnum
));
2002 struct resources fset
;
2003 CLEAR_RESOURCE (&needed
);
2004 CLEAR_RESOURCE (&set
);
2005 mark_set_resources (insn
, &set
, 0, MARK_SRC_DEST
);
2008 CLEAR_RESOURCE (&fset
);
2009 mark_set_resources (insn
, &fset
, 0, MARK_SRC_DEST
);
2011 mark_referenced_resources (insn
, &needed
, false);
2013 for (trial
= prev_nonnote_insn (insn
); ! stop_search_p (trial
, 1);
2016 next_trial
= prev_nonnote_insn (trial
);
2018 /* This must be an INSN or CALL_INSN. */
2019 pat
= PATTERN (trial
);
2021 /* Stand-alone USE and CLOBBER are just for flow. */
2022 if (GET_CODE (pat
) == USE
|| GET_CODE (pat
) == CLOBBER
)
2025 /* Check for resource conflict first, to avoid unnecessary
2027 if (! insn_references_resource_p (trial
, &set
, true)
2028 && ! insn_sets_resource_p (trial
,
2029 filter_flags
? &fset
: &set
,
2031 && ! insn_sets_resource_p (trial
, &needed
, true)
2032 /* Can't separate set of cc0 from its use. */
2033 && (!HAVE_cc0
|| ! (reg_mentioned_p (cc0_rtx
, pat
) && ! sets_cc0_p (pat
)))
2034 && ! can_throw_internal (trial
))
2036 trial
= try_split (pat
, trial
, 1);
2037 next_trial
= prev_nonnote_insn (trial
);
2038 if (eligible_for_delay (insn
, slots_filled
, trial
, flags
))
2040 /* In this case, we are searching backward, so if we
2041 find insns to put on the delay list, we want
2042 to put them at the head, rather than the
2043 tail, of the list. */
2045 update_reg_dead_notes (trial
, insn
);
2046 delay_list
.safe_insert (0, trial
);
2047 update_block (trial
, trial
);
2048 delete_related_insns (trial
);
2049 if (slots_to_fill
== ++slots_filled
)
2055 mark_set_resources (trial
, &set
, 0, MARK_SRC_DEST_CALL
);
2058 mark_set_resources (trial
, &fset
, 0, MARK_SRC_DEST_CALL
);
2059 /* If the flags register is set, then it doesn't create RAW
2060 dependencies any longer and it also doesn't create WAW
2061 dependencies since it's dead after the original insn. */
2062 if (TEST_HARD_REG_BIT (fset
.regs
, targetm
.flags_regnum
))
2064 CLEAR_HARD_REG_BIT (needed
.regs
, targetm
.flags_regnum
);
2065 CLEAR_HARD_REG_BIT (fset
.regs
, targetm
.flags_regnum
);
2068 mark_referenced_resources (trial
, &needed
, true);
2072 /* If all needed slots haven't been filled, we come here. */
2074 /* Try to optimize case of jumping around a single insn. */
2075 if ((ANNUL_IFTRUE_SLOTS
|| ANNUL_IFFALSE_SLOTS
)
2076 && slots_filled
!= slots_to_fill
2077 && delay_list
.is_empty ()
2079 && (condjump_p (insn
) || condjump_in_parallel_p (insn
))
2080 && !ANY_RETURN_P (JUMP_LABEL (insn
)))
2082 optimize_skip (as_a
<rtx_jump_insn
*> (insn
), &delay_list
);
2083 if (!delay_list
.is_empty ())
2087 /* Try to get insns from beyond the insn needing the delay slot.
2088 These insns can neither set or reference resources set in insns being
2089 skipped, cannot set resources in the insn being skipped, and, if this
2090 is a CALL_INSN (or a CALL_INSN is passed), cannot trap (because the
2091 call might not return).
2093 There used to be code which continued past the target label if
2094 we saw all uses of the target label. This code did not work,
2095 because it failed to account for some instructions which were
2096 both annulled and marked as from the target. This can happen as a
2097 result of optimize_skip. Since this code was redundant with
2098 fill_eager_delay_slots anyways, it was just deleted. */
2100 if (slots_filled
!= slots_to_fill
2101 /* If this instruction could throw an exception which is
2102 caught in the same function, then it's not safe to fill
2103 the delay slot with an instruction from beyond this
2104 point. For example, consider:
2115 Even though `i' is a local variable, we must be sure not
2116 to put `i = 3' in the delay slot if `f' might throw an
2119 Presumably, we should also check to see if we could get
2120 back to this function via `setjmp'. */
2121 && ! can_throw_internal (insn
)
2124 int maybe_never
= 0;
2125 rtx pat
, trial_delay
;
2127 CLEAR_RESOURCE (&needed
);
2128 CLEAR_RESOURCE (&set
);
2129 mark_set_resources (insn
, &set
, 0, MARK_SRC_DEST_CALL
);
2130 mark_referenced_resources (insn
, &needed
, true);
2135 for (trial
= next_nonnote_insn (insn
); !stop_search_p (trial
, 1);
2138 next_trial
= next_nonnote_insn (trial
);
2140 /* This must be an INSN or CALL_INSN. */
2141 pat
= PATTERN (trial
);
2143 /* Stand-alone USE and CLOBBER are just for flow. */
2144 if (GET_CODE (pat
) == USE
|| GET_CODE (pat
) == CLOBBER
)
2147 /* If this already has filled delay slots, get the insn needing
2149 if (GET_CODE (pat
) == SEQUENCE
)
2150 trial_delay
= XVECEXP (pat
, 0, 0);
2152 trial_delay
= trial
;
2154 /* Stop our search when seeing a jump. */
2155 if (JUMP_P (trial_delay
))
2158 /* See if we have a resource problem before we try to split. */
2159 if (GET_CODE (pat
) != SEQUENCE
2160 && ! insn_references_resource_p (trial
, &set
, true)
2161 && ! insn_sets_resource_p (trial
, &set
, true)
2162 && ! insn_sets_resource_p (trial
, &needed
, true)
2163 && (!HAVE_cc0
&& ! (reg_mentioned_p (cc0_rtx
, pat
) && ! sets_cc0_p (pat
)))
2164 && ! (maybe_never
&& may_trap_or_fault_p (pat
))
2165 && (trial
= try_split (pat
, trial
, 0))
2166 && eligible_for_delay (insn
, slots_filled
, trial
, flags
)
2167 && ! can_throw_internal (trial
))
2169 next_trial
= next_nonnote_insn (trial
);
2170 add_to_delay_list (trial
, &delay_list
);
2171 if (HAVE_cc0
&& reg_mentioned_p (cc0_rtx
, pat
))
2172 link_cc0_insns (trial
);
2174 delete_related_insns (trial
);
2175 if (slots_to_fill
== ++slots_filled
)
2180 mark_set_resources (trial
, &set
, 0, MARK_SRC_DEST_CALL
);
2181 mark_referenced_resources (trial
, &needed
, true);
2183 /* Ensure we don't put insns between the setting of cc and the
2184 comparison by moving a setting of cc into an earlier delay
2185 slot since these insns could clobber the condition code. */
2188 /* If this is a call, we might not get here. */
2189 if (CALL_P (trial_delay
))
2193 /* If there are slots left to fill and our search was stopped by an
2194 unconditional branch, try the insn at the branch target. We can
2195 redirect the branch if it works.
2197 Don't do this if the insn at the branch target is a branch. */
2198 if (slots_to_fill
!= slots_filled
2200 && jump_to_label_p (trial
)
2201 && simplejump_p (trial
)
2202 && (next_trial
= next_active_insn (JUMP_LABEL_AS_INSN (trial
))) != 0
2203 && ! (NONJUMP_INSN_P (next_trial
)
2204 && GET_CODE (PATTERN (next_trial
)) == SEQUENCE
)
2205 && !JUMP_P (next_trial
)
2206 && ! insn_references_resource_p (next_trial
, &set
, true)
2207 && ! insn_sets_resource_p (next_trial
, &set
, true)
2208 && ! insn_sets_resource_p (next_trial
, &needed
, true)
2209 && (!HAVE_cc0
|| ! reg_mentioned_p (cc0_rtx
, PATTERN (next_trial
)))
2210 && ! (maybe_never
&& may_trap_or_fault_p (PATTERN (next_trial
)))
2211 && (next_trial
= try_split (PATTERN (next_trial
), next_trial
, 0))
2212 && eligible_for_delay (insn
, slots_filled
, next_trial
, flags
)
2213 && ! can_throw_internal (trial
))
2215 /* See comment in relax_delay_slots about necessity of using
2216 next_real_insn here. */
2217 rtx_insn
*new_label
= next_real_insn (next_trial
);
2220 new_label
= get_label_before (new_label
, JUMP_LABEL (trial
));
2222 new_label
= find_end_label (simple_return_rtx
);
2226 add_to_delay_list (copy_delay_slot_insn (next_trial
),
2229 reorg_redirect_jump (as_a
<rtx_jump_insn
*> (trial
),
2235 /* If this is an unconditional jump, then try to get insns from the
2236 target of the jump. */
2237 rtx_jump_insn
*jump_insn
;
2238 if ((jump_insn
= dyn_cast
<rtx_jump_insn
*> (insn
))
2239 && simplejump_p (jump_insn
)
2240 && slots_filled
!= slots_to_fill
)
2241 fill_slots_from_thread (jump_insn
, const_true_rtx
,
2242 next_active_insn (JUMP_LABEL_AS_INSN (insn
)),
2243 NULL
, 1, 1, own_thread_p (JUMP_LABEL (insn
),
2244 JUMP_LABEL (insn
), 0),
2245 slots_to_fill
, &slots_filled
, &delay_list
);
2247 if (!delay_list
.is_empty ())
2248 unfilled_slots_base
[i
]
2249 = emit_delay_sequence (insn
, delay_list
, slots_filled
);
2251 if (slots_to_fill
== slots_filled
)
2252 unfilled_slots_base
[i
] = 0;
2254 note_delay_statistics (slots_filled
, 0);
2258 /* Follow any unconditional jump at LABEL, for the purpose of redirecting JUMP;
2259 return the ultimate label reached by any such chain of jumps.
2260 Return a suitable return rtx if the chain ultimately leads to a
2262 If LABEL is not followed by a jump, return LABEL.
2263 If the chain loops or we can't find end, return LABEL,
2264 since that tells caller to avoid changing the insn.
2265 If the returned label is obtained by following a crossing jump,
2266 set *CROSSING to true, otherwise set it to false. */
2269 follow_jumps (rtx label
, rtx_insn
*jump
, bool *crossing
)
2276 if (ANY_RETURN_P (label
))
2279 rtx_insn
*value
= as_a
<rtx_insn
*> (label
);
2283 && (insn
= next_active_insn (value
)) != 0
2285 && JUMP_LABEL (insn
) != NULL_RTX
2286 && ((any_uncondjump_p (insn
) && onlyjump_p (insn
))
2287 || ANY_RETURN_P (PATTERN (insn
)))
2288 && (next
= NEXT_INSN (insn
))
2289 && BARRIER_P (next
));
2292 rtx this_label_or_return
= JUMP_LABEL (insn
);
2294 /* If we have found a cycle, make the insn jump to itself. */
2295 if (this_label_or_return
== label
)
2298 /* Cannot follow returns and cannot look through tablejumps. */
2299 if (ANY_RETURN_P (this_label_or_return
))
2300 return this_label_or_return
;
2302 rtx_insn
*this_label
= as_a
<rtx_insn
*> (this_label_or_return
);
2303 if (NEXT_INSN (this_label
)
2304 && JUMP_TABLE_DATA_P (NEXT_INSN (this_label
)))
2307 if (!targetm
.can_follow_jump (jump
, insn
))
2310 *crossing
= CROSSING_JUMP_P (jump
);
2318 /* Try to find insns to place in delay slots.
2320 INSN is the jump needing SLOTS_TO_FILL delay slots. It tests CONDITION
2321 or is an unconditional branch if CONDITION is const_true_rtx.
2322 *PSLOTS_FILLED is updated with the number of slots that we have filled.
2324 THREAD is a flow-of-control, either the insns to be executed if the
2325 branch is true or if the branch is false, THREAD_IF_TRUE says which.
2327 OPPOSITE_THREAD is the thread in the opposite direction. It is used
2328 to see if any potential delay slot insns set things needed there.
2330 LIKELY is nonzero if it is extremely likely that the branch will be
2331 taken and THREAD_IF_TRUE is set. This is used for the branch at the
2332 end of a loop back up to the top.
2334 OWN_THREAD and OWN_OPPOSITE_THREAD are true if we are the only user of the
2335 thread. I.e., it is the fallthrough code of our jump or the target of the
2336 jump when we are the only jump going there.
2338 If OWN_THREAD is false, it must be the "true" thread of a jump. In that
2339 case, we can only take insns from the head of the thread for our delay
2340 slot. We then adjust the jump to point after the insns we have taken. */
2343 fill_slots_from_thread (rtx_jump_insn
*insn
, rtx condition
,
2344 rtx thread_or_return
, rtx opposite_thread
, int likely
,
2345 int thread_if_true
, int own_thread
, int slots_to_fill
,
2346 int *pslots_filled
, vec
<rtx_insn
*> *delay_list
)
2349 struct resources opposite_needed
, set
, needed
;
2355 /* Validate our arguments. */
2356 gcc_assert (condition
!= const_true_rtx
|| thread_if_true
);
2357 gcc_assert (own_thread
|| thread_if_true
);
2359 flags
= get_jump_flags (insn
, JUMP_LABEL (insn
));
2361 /* If our thread is the end of subroutine, we can't get any delay
2363 if (thread_or_return
== NULL_RTX
|| ANY_RETURN_P (thread_or_return
))
2366 rtx_insn
*thread
= as_a
<rtx_insn
*> (thread_or_return
);
2368 /* If this is an unconditional branch, nothing is needed at the
2369 opposite thread. Otherwise, compute what is needed there. */
2370 if (condition
== const_true_rtx
)
2371 CLEAR_RESOURCE (&opposite_needed
);
2373 mark_target_live_regs (get_insns (), opposite_thread
, &opposite_needed
);
2375 /* If the insn at THREAD can be split, do it here to avoid having to
2376 update THREAD and NEW_THREAD if it is done in the loop below. Also
2377 initialize NEW_THREAD. */
2379 new_thread
= thread
= try_split (PATTERN (thread
), thread
, 0);
2381 /* Scan insns at THREAD. We are looking for an insn that can be removed
2382 from THREAD (it neither sets nor references resources that were set
2383 ahead of it and it doesn't set anything needs by the insns ahead of
2384 it) and that either can be placed in an annulling insn or aren't
2385 needed at OPPOSITE_THREAD. */
2387 CLEAR_RESOURCE (&needed
);
2388 CLEAR_RESOURCE (&set
);
2390 /* If we do not own this thread, we must stop as soon as we find
2391 something that we can't put in a delay slot, since all we can do
2392 is branch into THREAD at a later point. Therefore, labels stop
2393 the search if this is not the `true' thread. */
2395 for (trial
= thread
;
2396 ! stop_search_p (trial
, ! thread_if_true
) && (! lose
|| own_thread
);
2397 trial
= next_nonnote_insn (trial
))
2401 /* If we have passed a label, we no longer own this thread. */
2402 if (LABEL_P (trial
))
2408 pat
= PATTERN (trial
);
2409 if (GET_CODE (pat
) == USE
|| GET_CODE (pat
) == CLOBBER
)
2412 /* If TRIAL conflicts with the insns ahead of it, we lose. Also,
2413 don't separate or copy insns that set and use CC0. */
2414 if (! insn_references_resource_p (trial
, &set
, true)
2415 && ! insn_sets_resource_p (trial
, &set
, true)
2416 && ! insn_sets_resource_p (trial
, &needed
, true)
2417 && (!HAVE_cc0
|| (! (reg_mentioned_p (cc0_rtx
, pat
)
2418 && (! own_thread
|| ! sets_cc0_p (pat
)))))
2419 && ! can_throw_internal (trial
))
2421 rtx_insn
*prior_insn
;
2423 /* If TRIAL is redundant with some insn before INSN, we don't
2424 actually need to add it to the delay list; we can merely pretend
2426 if ((prior_insn
= redundant_insn (trial
, insn
, *delay_list
)))
2428 fix_reg_dead_note (prior_insn
, insn
);
2431 update_block (trial
, thread
);
2432 if (trial
== thread
)
2434 thread
= next_active_insn (thread
);
2435 if (new_thread
== trial
)
2436 new_thread
= thread
;
2439 delete_related_insns (trial
);
2443 update_reg_unused_notes (prior_insn
, trial
);
2444 new_thread
= next_active_insn (trial
);
2450 /* There are two ways we can win: If TRIAL doesn't set anything
2451 needed at the opposite thread and can't trap, or if it can
2452 go into an annulled delay slot. But we want neither to copy
2453 nor to speculate frame-related insns. */
2455 && ((condition
== const_true_rtx
2456 && (own_thread
|| !RTX_FRAME_RELATED_P (trial
)))
2457 || (! insn_sets_resource_p (trial
, &opposite_needed
, true)
2458 && ! may_trap_or_fault_p (pat
)
2459 && ! RTX_FRAME_RELATED_P (trial
))))
2462 trial
= try_split (pat
, trial
, 0);
2463 if (new_thread
== old_trial
)
2465 if (thread
== old_trial
)
2467 pat
= PATTERN (trial
);
2468 if (eligible_for_delay (insn
, *pslots_filled
, trial
, flags
))
2471 else if (!RTX_FRAME_RELATED_P (trial
)
2472 && ((ANNUL_IFTRUE_SLOTS
&& ! thread_if_true
)
2473 || (ANNUL_IFFALSE_SLOTS
&& thread_if_true
)))
2476 trial
= try_split (pat
, trial
, 0);
2477 if (new_thread
== old_trial
)
2479 if (thread
== old_trial
)
2481 pat
= PATTERN (trial
);
2482 if ((must_annul
|| delay_list
->is_empty ()) && (thread_if_true
2483 ? check_annul_list_true_false (0, *delay_list
)
2484 && eligible_for_annul_false (insn
, *pslots_filled
, trial
, flags
)
2485 : check_annul_list_true_false (1, *delay_list
)
2486 && eligible_for_annul_true (insn
, *pslots_filled
, trial
, flags
)))
2493 if (HAVE_cc0
&& reg_mentioned_p (cc0_rtx
, pat
))
2494 link_cc0_insns (trial
);
2496 /* If we own this thread, delete the insn. If this is the
2497 destination of a branch, show that a basic block status
2498 may have been updated. In any case, mark the new
2499 starting point of this thread. */
2504 update_block (trial
, thread
);
2505 if (trial
== thread
)
2507 thread
= next_active_insn (thread
);
2508 if (new_thread
== trial
)
2509 new_thread
= thread
;
2512 /* We are moving this insn, not deleting it. We must
2513 temporarily increment the use count on any referenced
2514 label lest it be deleted by delete_related_insns. */
2515 for (note
= REG_NOTES (trial
);
2517 note
= XEXP (note
, 1))
2518 if (REG_NOTE_KIND (note
) == REG_LABEL_OPERAND
2519 || REG_NOTE_KIND (note
) == REG_LABEL_TARGET
)
2521 /* REG_LABEL_OPERAND could be
2522 NOTE_INSN_DELETED_LABEL too. */
2523 if (LABEL_P (XEXP (note
, 0)))
2524 LABEL_NUSES (XEXP (note
, 0))++;
2526 gcc_assert (REG_NOTE_KIND (note
)
2527 == REG_LABEL_OPERAND
);
2529 if (jump_to_label_p (trial
))
2530 LABEL_NUSES (JUMP_LABEL (trial
))++;
2532 delete_related_insns (trial
);
2534 for (note
= REG_NOTES (trial
);
2536 note
= XEXP (note
, 1))
2537 if (REG_NOTE_KIND (note
) == REG_LABEL_OPERAND
2538 || REG_NOTE_KIND (note
) == REG_LABEL_TARGET
)
2540 /* REG_LABEL_OPERAND could be
2541 NOTE_INSN_DELETED_LABEL too. */
2542 if (LABEL_P (XEXP (note
, 0)))
2543 LABEL_NUSES (XEXP (note
, 0))--;
2545 gcc_assert (REG_NOTE_KIND (note
)
2546 == REG_LABEL_OPERAND
);
2548 if (jump_to_label_p (trial
))
2549 LABEL_NUSES (JUMP_LABEL (trial
))--;
2552 new_thread
= next_active_insn (trial
);
2554 temp
= own_thread
? trial
: copy_delay_slot_insn (trial
);
2556 INSN_FROM_TARGET_P (temp
) = 1;
2558 add_to_delay_list (temp
, delay_list
);
2560 if (slots_to_fill
== ++(*pslots_filled
))
2562 /* Even though we have filled all the slots, we
2563 may be branching to a location that has a
2564 redundant insn. Skip any if so. */
2565 while (new_thread
&& ! own_thread
2566 && ! insn_sets_resource_p (new_thread
, &set
, true)
2567 && ! insn_sets_resource_p (new_thread
, &needed
,
2569 && ! insn_references_resource_p (new_thread
,
2572 = redundant_insn (new_thread
, insn
,
2575 /* We know we do not own the thread, so no need
2576 to call update_block and delete_insn. */
2577 fix_reg_dead_note (prior_insn
, insn
);
2578 update_reg_unused_notes (prior_insn
, new_thread
);
2580 = next_active_insn (as_a
<rtx_insn
*> (new_thread
));
2590 /* This insn can't go into a delay slot. */
2592 mark_set_resources (trial
, &set
, 0, MARK_SRC_DEST_CALL
);
2593 mark_referenced_resources (trial
, &needed
, true);
2595 /* Ensure we don't put insns between the setting of cc and the comparison
2596 by moving a setting of cc into an earlier delay slot since these insns
2597 could clobber the condition code. */
2600 /* If this insn is a register-register copy and the next insn has
2601 a use of our destination, change it to use our source. That way,
2602 it will become a candidate for our delay slot the next time
2603 through this loop. This case occurs commonly in loops that
2606 We could check for more complex cases than those tested below,
2607 but it doesn't seem worth it. It might also be a good idea to try
2608 to swap the two insns. That might do better.
2610 We can't do this if the next insn modifies our destination, because
2611 that would make the replacement into the insn invalid. We also can't
2612 do this if it modifies our source, because it might be an earlyclobber
2613 operand. This latter test also prevents updating the contents of
2614 a PRE_INC. We also can't do this if there's overlap of source and
2615 destination. Overlap may happen for larger-than-register-size modes. */
2617 if (NONJUMP_INSN_P (trial
) && GET_CODE (pat
) == SET
2618 && REG_P (SET_SRC (pat
))
2619 && REG_P (SET_DEST (pat
))
2620 && !reg_overlap_mentioned_p (SET_DEST (pat
), SET_SRC (pat
)))
2622 rtx_insn
*next
= next_nonnote_insn (trial
);
2624 if (next
&& NONJUMP_INSN_P (next
)
2625 && GET_CODE (PATTERN (next
)) != USE
2626 && ! reg_set_p (SET_DEST (pat
), next
)
2627 && ! reg_set_p (SET_SRC (pat
), next
)
2628 && reg_referenced_p (SET_DEST (pat
), PATTERN (next
))
2629 && ! modified_in_p (SET_DEST (pat
), next
))
2630 validate_replace_rtx (SET_DEST (pat
), SET_SRC (pat
), next
);
2634 /* If we stopped on a branch insn that has delay slots, see if we can
2635 steal some of the insns in those slots. */
2636 if (trial
&& NONJUMP_INSN_P (trial
)
2637 && GET_CODE (PATTERN (trial
)) == SEQUENCE
2638 && JUMP_P (XVECEXP (PATTERN (trial
), 0, 0)))
2640 rtx_sequence
*sequence
= as_a
<rtx_sequence
*> (PATTERN (trial
));
2641 /* If this is the `true' thread, we will want to follow the jump,
2642 so we can only do this if we have taken everything up to here. */
2643 if (thread_if_true
&& trial
== new_thread
)
2645 steal_delay_list_from_target (insn
, condition
, sequence
,
2646 delay_list
, &set
, &needed
,
2647 &opposite_needed
, slots_to_fill
,
2648 pslots_filled
, &must_annul
,
2650 /* If we owned the thread and are told that it branched
2651 elsewhere, make sure we own the thread at the new location. */
2652 if (own_thread
&& trial
!= new_thread
)
2653 own_thread
= own_thread_p (new_thread
, new_thread
, 0);
2655 else if (! thread_if_true
)
2656 steal_delay_list_from_fallthrough (insn
, condition
, sequence
,
2657 delay_list
, &set
, &needed
,
2658 &opposite_needed
, slots_to_fill
,
2659 pslots_filled
, &must_annul
);
2662 /* If we haven't found anything for this delay slot and it is very
2663 likely that the branch will be taken, see if the insn at our target
2664 increments or decrements a register with an increment that does not
2665 depend on the destination register. If so, try to place the opposite
2666 arithmetic insn after the jump insn and put the arithmetic insn in the
2667 delay slot. If we can't do this, return. */
2668 if (delay_list
->is_empty () && likely
2669 && new_thread
&& !ANY_RETURN_P (new_thread
)
2670 && NONJUMP_INSN_P (new_thread
)
2671 && !RTX_FRAME_RELATED_P (new_thread
)
2672 && GET_CODE (PATTERN (new_thread
)) != ASM_INPUT
2673 && asm_noperands (PATTERN (new_thread
)) < 0)
2675 rtx pat
= PATTERN (new_thread
);
2679 /* We know "new_thread" is an insn due to NONJUMP_INSN_P (new_thread)
2681 trial
= as_a
<rtx_insn
*> (new_thread
);
2682 pat
= PATTERN (trial
);
2684 if (!NONJUMP_INSN_P (trial
)
2685 || GET_CODE (pat
) != SET
2686 || ! eligible_for_delay (insn
, 0, trial
, flags
)
2687 || can_throw_internal (trial
))
2690 dest
= SET_DEST (pat
), src
= SET_SRC (pat
);
2691 if ((GET_CODE (src
) == PLUS
|| GET_CODE (src
) == MINUS
)
2692 && rtx_equal_p (XEXP (src
, 0), dest
)
2693 && (!FLOAT_MODE_P (GET_MODE (src
))
2694 || flag_unsafe_math_optimizations
)
2695 && ! reg_overlap_mentioned_p (dest
, XEXP (src
, 1))
2696 && ! side_effects_p (pat
))
2698 rtx other
= XEXP (src
, 1);
2702 /* If this is a constant adjustment, use the same code with
2703 the negated constant. Otherwise, reverse the sense of the
2705 if (CONST_INT_P (other
))
2706 new_arith
= gen_rtx_fmt_ee (GET_CODE (src
), GET_MODE (src
), dest
,
2707 negate_rtx (GET_MODE (src
), other
));
2709 new_arith
= gen_rtx_fmt_ee (GET_CODE (src
) == PLUS
? MINUS
: PLUS
,
2710 GET_MODE (src
), dest
, other
);
2712 ninsn
= emit_insn_after (gen_rtx_SET (dest
, new_arith
), insn
);
2714 if (recog_memoized (ninsn
) < 0
2715 || (extract_insn (ninsn
),
2716 !constrain_operands (1, get_preferred_alternatives (ninsn
))))
2718 delete_related_insns (ninsn
);
2724 update_block (trial
, thread
);
2725 if (trial
== thread
)
2727 thread
= next_active_insn (thread
);
2728 if (new_thread
== trial
)
2729 new_thread
= thread
;
2731 delete_related_insns (trial
);
2734 new_thread
= next_active_insn (trial
);
2736 ninsn
= own_thread
? trial
: copy_delay_slot_insn (trial
);
2738 INSN_FROM_TARGET_P (ninsn
) = 1;
2740 add_to_delay_list (ninsn
, delay_list
);
2745 if (!delay_list
->is_empty () && must_annul
)
2746 INSN_ANNULLED_BRANCH_P (insn
) = 1;
2748 /* If we are to branch into the middle of this thread, find an appropriate
2749 label or make a new one if none, and redirect INSN to it. If we hit the
2750 end of the function, use the end-of-function label. */
2751 if (new_thread
!= thread
)
2754 bool crossing
= false;
2756 gcc_assert (thread_if_true
);
2758 if (new_thread
&& simplejump_or_return_p (new_thread
)
2759 && redirect_with_delay_list_safe_p (insn
,
2760 JUMP_LABEL (new_thread
),
2762 new_thread
= follow_jumps (JUMP_LABEL (new_thread
), insn
,
2765 if (ANY_RETURN_P (new_thread
))
2766 label
= find_end_label (new_thread
);
2767 else if (LABEL_P (new_thread
))
2770 label
= get_label_before (as_a
<rtx_insn
*> (new_thread
),
2775 reorg_redirect_jump (insn
, label
);
2777 CROSSING_JUMP_P (insn
) = 1;
2782 /* Make another attempt to find insns to place in delay slots.
2784 We previously looked for insns located in front of the delay insn
2785 and, for non-jump delay insns, located behind the delay insn.
2787 Here only try to schedule jump insns and try to move insns from either
2788 the target or the following insns into the delay slot. If annulling is
2789 supported, we will be likely to do this. Otherwise, we can do this only
2793 fill_eager_delay_slots (void)
2797 int num_unfilled_slots
= unfilled_slots_next
- unfilled_slots_base
;
2799 for (i
= 0; i
< num_unfilled_slots
; i
++)
2802 rtx target_label
, insn_at_target
;
2803 rtx_insn
*fallthrough_insn
;
2804 auto_vec
<rtx_insn
*, 5> delay_list
;
2805 rtx_jump_insn
*jump_insn
;
2807 int own_fallthrough
;
2808 int prediction
, slots_to_fill
, slots_filled
;
2810 insn
= unfilled_slots_base
[i
];
2813 || ! (jump_insn
= dyn_cast
<rtx_jump_insn
*> (insn
))
2814 || ! (condjump_p (jump_insn
) || condjump_in_parallel_p (jump_insn
)))
2817 slots_to_fill
= num_delay_slots (jump_insn
);
2818 /* Some machine description have defined instructions to have
2819 delay slots only in certain circumstances which may depend on
2820 nearby insns (which change due to reorg's actions).
2822 For example, the PA port normally has delay slots for unconditional
2825 However, the PA port claims such jumps do not have a delay slot
2826 if they are immediate successors of certain CALL_INSNs. This
2827 allows the port to favor filling the delay slot of the call with
2828 the unconditional jump. */
2829 if (slots_to_fill
== 0)
2833 target_label
= JUMP_LABEL (jump_insn
);
2834 condition
= get_branch_condition (jump_insn
, target_label
);
2839 /* Get the next active fallthrough and target insns and see if we own
2840 them. Then see whether the branch is likely true. We don't need
2841 to do a lot of this for unconditional branches. */
2843 insn_at_target
= first_active_target_insn (target_label
);
2844 own_target
= own_thread_p (target_label
, target_label
, 0);
2846 if (condition
== const_true_rtx
)
2848 own_fallthrough
= 0;
2849 fallthrough_insn
= 0;
2854 fallthrough_insn
= next_active_insn (jump_insn
);
2855 own_fallthrough
= own_thread_p (NEXT_INSN (jump_insn
), NULL_RTX
, 1);
2856 prediction
= mostly_true_jump (jump_insn
);
2859 /* If this insn is expected to branch, first try to get insns from our
2860 target, then our fallthrough insns. If it is not expected to branch,
2861 try the other order. */
2865 fill_slots_from_thread (jump_insn
, condition
, insn_at_target
,
2866 fallthrough_insn
, prediction
== 2, 1,
2868 slots_to_fill
, &slots_filled
, &delay_list
);
2870 if (delay_list
.is_empty () && own_fallthrough
)
2872 /* Even though we didn't find anything for delay slots,
2873 we might have found a redundant insn which we deleted
2874 from the thread that was filled. So we have to recompute
2875 the next insn at the target. */
2876 target_label
= JUMP_LABEL (jump_insn
);
2877 insn_at_target
= first_active_target_insn (target_label
);
2879 fill_slots_from_thread (jump_insn
, condition
, fallthrough_insn
,
2880 insn_at_target
, 0, 0, own_fallthrough
,
2881 slots_to_fill
, &slots_filled
,
2887 if (own_fallthrough
)
2888 fill_slots_from_thread (jump_insn
, condition
, fallthrough_insn
,
2889 insn_at_target
, 0, 0, own_fallthrough
,
2890 slots_to_fill
, &slots_filled
, &delay_list
);
2892 if (delay_list
.is_empty ())
2893 fill_slots_from_thread (jump_insn
, condition
, insn_at_target
,
2894 next_active_insn (insn
), 0, 1, own_target
,
2895 slots_to_fill
, &slots_filled
, &delay_list
);
2898 if (!delay_list
.is_empty ())
2899 unfilled_slots_base
[i
]
2900 = emit_delay_sequence (jump_insn
, delay_list
, slots_filled
);
2902 if (slots_to_fill
== slots_filled
)
2903 unfilled_slots_base
[i
] = 0;
2905 note_delay_statistics (slots_filled
, 1);
2909 static void delete_computation (rtx_insn
*insn
);
2911 /* Recursively delete prior insns that compute the value (used only by INSN
2912 which the caller is deleting) stored in the register mentioned by NOTE
2913 which is a REG_DEAD note associated with INSN. */
2916 delete_prior_computation (rtx note
, rtx_insn
*insn
)
2919 rtx reg
= XEXP (note
, 0);
2921 for (our_prev
= prev_nonnote_insn (insn
);
2922 our_prev
&& (NONJUMP_INSN_P (our_prev
)
2923 || CALL_P (our_prev
));
2924 our_prev
= prev_nonnote_insn (our_prev
))
2926 rtx pat
= PATTERN (our_prev
);
2928 /* If we reach a CALL which is not calling a const function
2929 or the callee pops the arguments, then give up. */
2930 if (CALL_P (our_prev
)
2931 && (! RTL_CONST_CALL_P (our_prev
)
2932 || GET_CODE (pat
) != SET
|| GET_CODE (SET_SRC (pat
)) != CALL
))
2935 /* If we reach a SEQUENCE, it is too complex to try to
2936 do anything with it, so give up. We can be run during
2937 and after reorg, so SEQUENCE rtl can legitimately show
2939 if (GET_CODE (pat
) == SEQUENCE
)
2942 if (GET_CODE (pat
) == USE
2943 && NONJUMP_INSN_P (XEXP (pat
, 0)))
2944 /* reorg creates USEs that look like this. We leave them
2945 alone because reorg needs them for its own purposes. */
2948 if (reg_set_p (reg
, pat
))
2950 if (side_effects_p (pat
) && !CALL_P (our_prev
))
2953 if (GET_CODE (pat
) == PARALLEL
)
2955 /* If we find a SET of something else, we can't
2960 for (i
= 0; i
< XVECLEN (pat
, 0); i
++)
2962 rtx part
= XVECEXP (pat
, 0, i
);
2964 if (GET_CODE (part
) == SET
2965 && SET_DEST (part
) != reg
)
2969 if (i
== XVECLEN (pat
, 0))
2970 delete_computation (our_prev
);
2972 else if (GET_CODE (pat
) == SET
2973 && REG_P (SET_DEST (pat
)))
2975 int dest_regno
= REGNO (SET_DEST (pat
));
2976 int dest_endregno
= END_REGNO (SET_DEST (pat
));
2977 int regno
= REGNO (reg
);
2978 int endregno
= END_REGNO (reg
);
2980 if (dest_regno
>= regno
2981 && dest_endregno
<= endregno
)
2982 delete_computation (our_prev
);
2984 /* We may have a multi-word hard register and some, but not
2985 all, of the words of the register are needed in subsequent
2986 insns. Write REG_UNUSED notes for those parts that were not
2988 else if (dest_regno
<= regno
2989 && dest_endregno
>= endregno
)
2993 add_reg_note (our_prev
, REG_UNUSED
, reg
);
2995 for (i
= dest_regno
; i
< dest_endregno
; i
++)
2996 if (! find_regno_note (our_prev
, REG_UNUSED
, i
))
2999 if (i
== dest_endregno
)
3000 delete_computation (our_prev
);
3007 /* If PAT references the register that dies here, it is an
3008 additional use. Hence any prior SET isn't dead. However, this
3009 insn becomes the new place for the REG_DEAD note. */
3010 if (reg_overlap_mentioned_p (reg
, pat
))
3012 XEXP (note
, 1) = REG_NOTES (our_prev
);
3013 REG_NOTES (our_prev
) = note
;
3019 /* Delete INSN and recursively delete insns that compute values used only
3020 by INSN. This uses the REG_DEAD notes computed during flow analysis.
3022 Look at all our REG_DEAD notes. If a previous insn does nothing other
3023 than set a register that dies in this insn, we can delete that insn
3026 On machines with CC0, if CC0 is used in this insn, we may be able to
3027 delete the insn that set it. */
3030 delete_computation (rtx_insn
*insn
)
3034 if (HAVE_cc0
&& reg_referenced_p (cc0_rtx
, PATTERN (insn
)))
3036 rtx_insn
*prev
= prev_nonnote_insn (insn
);
3037 /* We assume that at this stage
3038 CC's are always set explicitly
3039 and always immediately before the jump that
3040 will use them. So if the previous insn
3041 exists to set the CC's, delete it
3042 (unless it performs auto-increments, etc.). */
3043 if (prev
&& NONJUMP_INSN_P (prev
)
3044 && sets_cc0_p (PATTERN (prev
)))
3046 if (sets_cc0_p (PATTERN (prev
)) > 0
3047 && ! side_effects_p (PATTERN (prev
)))
3048 delete_computation (prev
);
3050 /* Otherwise, show that cc0 won't be used. */
3051 add_reg_note (prev
, REG_UNUSED
, cc0_rtx
);
3055 for (note
= REG_NOTES (insn
); note
; note
= next
)
3057 next
= XEXP (note
, 1);
3059 if (REG_NOTE_KIND (note
) != REG_DEAD
3060 /* Verify that the REG_NOTE is legitimate. */
3061 || !REG_P (XEXP (note
, 0)))
3064 delete_prior_computation (note
, insn
);
3067 delete_related_insns (insn
);
3070 /* If all INSN does is set the pc, delete it,
3071 and delete the insn that set the condition codes for it
3072 if that's what the previous thing was. */
3075 delete_jump (rtx_insn
*insn
)
3077 rtx set
= single_set (insn
);
3079 if (set
&& GET_CODE (SET_DEST (set
)) == PC
)
3080 delete_computation (insn
);
3084 label_before_next_insn (rtx_insn
*x
, rtx scan_limit
)
3086 rtx_insn
*insn
= next_active_insn (x
);
3089 insn
= PREV_INSN (insn
);
3090 if (insn
== scan_limit
|| insn
== NULL_RTX
)
3098 /* Return TRUE if there is a NOTE_INSN_SWITCH_TEXT_SECTIONS note in between
3102 switch_text_sections_between_p (const rtx_insn
*beg
, const rtx_insn
*end
)
3105 for (p
= beg
; p
!= end
; p
= NEXT_INSN (p
))
3106 if (NOTE_P (p
) && NOTE_KIND (p
) == NOTE_INSN_SWITCH_TEXT_SECTIONS
)
3112 /* Once we have tried two ways to fill a delay slot, make a pass over the
3113 code to try to improve the results and to do such things as more jump
3117 relax_delay_slots (rtx_insn
*first
)
3119 rtx_insn
*insn
, *next
;
3122 rtx_insn
*delay_insn
;
3125 /* Look at every JUMP_INSN and see if we can improve it. */
3126 for (insn
= first
; insn
; insn
= next
)
3131 next
= next_active_insn (insn
);
3133 /* If this is a jump insn, see if it now jumps to a jump, jumps to
3134 the next insn, or jumps to a label that is not the last of a
3135 group of consecutive labels. */
3136 if (is_a
<rtx_jump_insn
*> (insn
)
3137 && (condjump_p (insn
) || condjump_in_parallel_p (insn
))
3138 && !ANY_RETURN_P (target_label
= JUMP_LABEL (insn
)))
3140 rtx_jump_insn
*jump_insn
= as_a
<rtx_jump_insn
*> (insn
);
3142 = skip_consecutive_labels (follow_jumps (target_label
, jump_insn
,
3144 if (ANY_RETURN_P (target_label
))
3145 target_label
= find_end_label (target_label
);
3148 && next_active_insn (as_a
<rtx_insn
*> (target_label
)) == next
3149 && ! condjump_in_parallel_p (jump_insn
)
3150 && ! (next
&& switch_text_sections_between_p (jump_insn
, next
)))
3152 delete_jump (jump_insn
);
3156 if (target_label
&& target_label
!= JUMP_LABEL (jump_insn
))
3158 reorg_redirect_jump (jump_insn
, target_label
);
3160 CROSSING_JUMP_P (jump_insn
) = 1;
3163 /* See if this jump conditionally branches around an unconditional
3164 jump. If so, invert this jump and point it to the target of the
3165 second jump. Check if it's possible on the target. */
3166 if (next
&& simplejump_or_return_p (next
)
3167 && any_condjump_p (jump_insn
)
3169 && (next_active_insn (as_a
<rtx_insn
*> (target_label
))
3170 == next_active_insn (next
))
3171 && no_labels_between_p (jump_insn
, next
)
3172 && targetm
.can_follow_jump (jump_insn
, next
))
3174 rtx label
= JUMP_LABEL (next
);
3176 /* Be careful how we do this to avoid deleting code or
3177 labels that are momentarily dead. See similar optimization
3180 We also need to ensure we properly handle the case when
3181 invert_jump fails. */
3183 ++LABEL_NUSES (target_label
);
3184 if (!ANY_RETURN_P (label
))
3185 ++LABEL_NUSES (label
);
3187 if (invert_jump (jump_insn
, label
, 1))
3189 delete_related_insns (next
);
3193 if (!ANY_RETURN_P (label
))
3194 --LABEL_NUSES (label
);
3196 if (--LABEL_NUSES (target_label
) == 0)
3197 delete_related_insns (target_label
);
3203 /* If this is an unconditional jump and the previous insn is a
3204 conditional jump, try reversing the condition of the previous
3205 insn and swapping our targets. The next pass might be able to
3208 Don't do this if we expect the conditional branch to be true, because
3209 we would then be making the more common case longer. */
3211 if (simplejump_or_return_p (insn
)
3212 && (other
= prev_active_insn (insn
)) != 0
3213 && any_condjump_p (other
)
3214 && no_labels_between_p (other
, insn
)
3215 && 0 > mostly_true_jump (other
))
3217 rtx other_target
= JUMP_LABEL (other
);
3218 target_label
= JUMP_LABEL (insn
);
3220 if (invert_jump (as_a
<rtx_jump_insn
*> (other
), target_label
, 0))
3221 reorg_redirect_jump (as_a
<rtx_jump_insn
*> (insn
), other_target
);
3224 /* Now look only at cases where we have a filled delay slot. */
3225 if (!NONJUMP_INSN_P (insn
) || GET_CODE (PATTERN (insn
)) != SEQUENCE
)
3228 pat
= as_a
<rtx_sequence
*> (PATTERN (insn
));
3229 delay_insn
= pat
->insn (0);
3231 /* See if the first insn in the delay slot is redundant with some
3232 previous insn. Remove it from the delay slot if so; then set up
3233 to reprocess this insn. */
3234 if (redundant_insn (pat
->insn (1), delay_insn
, vNULL
))
3236 update_block (pat
->insn (1), insn
);
3237 delete_from_delay_slot (pat
->insn (1));
3238 next
= prev_active_insn (next
);
3242 /* See if we have a RETURN insn with a filled delay slot followed
3243 by a RETURN insn with an unfilled a delay slot. If so, we can delete
3244 the first RETURN (but not its delay insn). This gives the same
3245 effect in fewer instructions.
3247 Only do so if optimizing for size since this results in slower, but
3249 if (optimize_function_for_size_p (cfun
)
3250 && ANY_RETURN_P (PATTERN (delay_insn
))
3253 && PATTERN (next
) == PATTERN (delay_insn
))
3258 /* Delete the RETURN and just execute the delay list insns.
3260 We do this by deleting the INSN containing the SEQUENCE, then
3261 re-emitting the insns separately, and then deleting the RETURN.
3262 This allows the count of the jump target to be properly
3265 Note that we need to change the INSN_UID of the re-emitted insns
3266 since it is used to hash the insns for mark_target_live_regs and
3267 the re-emitted insns will no longer be wrapped up in a SEQUENCE.
3269 Clear the from target bit, since these insns are no longer
3271 for (i
= 0; i
< XVECLEN (pat
, 0); i
++)
3272 INSN_FROM_TARGET_P (XVECEXP (pat
, 0, i
)) = 0;
3274 trial
= PREV_INSN (insn
);
3275 delete_related_insns (insn
);
3276 gcc_assert (GET_CODE (pat
) == SEQUENCE
);
3277 add_insn_after (delay_insn
, trial
, NULL
);
3279 for (i
= 1; i
< pat
->len (); i
++)
3280 after
= emit_copy_of_insn_after (pat
->insn (i
), after
);
3281 delete_scheduled_jump (delay_insn
);
3285 /* Now look only at the cases where we have a filled JUMP_INSN. */
3286 rtx_jump_insn
*delay_jump_insn
=
3287 dyn_cast
<rtx_jump_insn
*> (delay_insn
);
3288 if (! delay_jump_insn
|| !(condjump_p (delay_jump_insn
)
3289 || condjump_in_parallel_p (delay_jump_insn
)))
3292 target_label
= JUMP_LABEL (delay_jump_insn
);
3293 if (target_label
&& ANY_RETURN_P (target_label
))
3296 /* If this jump goes to another unconditional jump, thread it, but
3297 don't convert a jump into a RETURN here. */
3298 trial
= skip_consecutive_labels (follow_jumps (target_label
,
3301 if (ANY_RETURN_P (trial
))
3302 trial
= find_end_label (trial
);
3304 if (trial
&& trial
!= target_label
3305 && redirect_with_delay_slots_safe_p (delay_jump_insn
, trial
, insn
))
3307 reorg_redirect_jump (delay_jump_insn
, trial
);
3308 target_label
= trial
;
3310 CROSSING_JUMP_P (delay_jump_insn
) = 1;
3313 /* If the first insn at TARGET_LABEL is redundant with a previous
3314 insn, redirect the jump to the following insn and process again.
3315 We use next_real_insn instead of next_active_insn so we
3316 don't skip USE-markers, or we'll end up with incorrect
3318 trial
= next_real_insn (target_label
);
3319 if (trial
&& GET_CODE (PATTERN (trial
)) != SEQUENCE
3320 && redundant_insn (trial
, insn
, vNULL
)
3321 && ! can_throw_internal (trial
))
3323 /* Figure out where to emit the special USE insn so we don't
3324 later incorrectly compute register live/death info. */
3325 rtx_insn
*tmp
= next_active_insn (as_a
<rtx_insn
*> (trial
));
3327 tmp
= find_end_label (simple_return_rtx
);
3331 /* Insert the special USE insn and update dataflow info.
3332 We know "trial" is an insn here as it is the output of
3333 next_real_insn () above. */
3334 update_block (as_a
<rtx_insn
*> (trial
), tmp
);
3336 /* Now emit a label before the special USE insn, and
3337 redirect our jump to the new label. */
3338 target_label
= get_label_before (PREV_INSN (tmp
), target_label
);
3339 reorg_redirect_jump (delay_jump_insn
, target_label
);
3345 /* Similarly, if it is an unconditional jump with one insn in its
3346 delay list and that insn is redundant, thread the jump. */
3347 rtx_sequence
*trial_seq
=
3348 trial
? dyn_cast
<rtx_sequence
*> (PATTERN (trial
)) : NULL
;
3350 && trial_seq
->len () == 2
3351 && JUMP_P (trial_seq
->insn (0))
3352 && simplejump_or_return_p (trial_seq
->insn (0))
3353 && redundant_insn (trial_seq
->insn (1), insn
, vNULL
))
3355 target_label
= JUMP_LABEL (trial_seq
->insn (0));
3356 if (ANY_RETURN_P (target_label
))
3357 target_label
= find_end_label (target_label
);
3360 && redirect_with_delay_slots_safe_p (delay_jump_insn
,
3361 target_label
, insn
))
3363 update_block (trial_seq
->insn (1), insn
);
3364 reorg_redirect_jump (delay_jump_insn
, target_label
);
3370 /* See if we have a simple (conditional) jump that is useless. */
3371 if (! INSN_ANNULLED_BRANCH_P (delay_jump_insn
)
3372 && ! condjump_in_parallel_p (delay_jump_insn
)
3373 && prev_active_insn (as_a
<rtx_insn
*> (target_label
)) == insn
3374 && ! BARRIER_P (prev_nonnote_insn (as_a
<rtx_insn
*> (target_label
)))
3375 /* If the last insn in the delay slot sets CC0 for some insn,
3376 various code assumes that it is in a delay slot. We could
3377 put it back where it belonged and delete the register notes,
3378 but it doesn't seem worthwhile in this uncommon case. */
3380 || ! find_reg_note (XVECEXP (pat
, 0, XVECLEN (pat
, 0) - 1),
3381 REG_CC_USER
, NULL_RTX
)))
3386 /* All this insn does is execute its delay list and jump to the
3387 following insn. So delete the jump and just execute the delay
3390 We do this by deleting the INSN containing the SEQUENCE, then
3391 re-emitting the insns separately, and then deleting the jump.
3392 This allows the count of the jump target to be properly
3395 Note that we need to change the INSN_UID of the re-emitted insns
3396 since it is used to hash the insns for mark_target_live_regs and
3397 the re-emitted insns will no longer be wrapped up in a SEQUENCE.
3399 Clear the from target bit, since these insns are no longer
3401 for (i
= 0; i
< XVECLEN (pat
, 0); i
++)
3402 INSN_FROM_TARGET_P (XVECEXP (pat
, 0, i
)) = 0;
3404 trial
= PREV_INSN (insn
);
3405 delete_related_insns (insn
);
3406 gcc_assert (GET_CODE (pat
) == SEQUENCE
);
3407 add_insn_after (delay_jump_insn
, trial
, NULL
);
3408 after
= delay_jump_insn
;
3409 for (i
= 1; i
< pat
->len (); i
++)
3410 after
= emit_copy_of_insn_after (pat
->insn (i
), after
);
3411 delete_scheduled_jump (delay_jump_insn
);
3415 /* See if this is an unconditional jump around a single insn which is
3416 identical to the one in its delay slot. In this case, we can just
3417 delete the branch and the insn in its delay slot. */
3418 if (next
&& NONJUMP_INSN_P (next
)
3419 && label_before_next_insn (next
, insn
) == target_label
3420 && simplejump_p (insn
)
3421 && XVECLEN (pat
, 0) == 2
3422 && rtx_equal_p (PATTERN (next
), PATTERN (pat
->insn (1))))
3424 delete_related_insns (insn
);
3428 /* See if this jump (with its delay slots) conditionally branches
3429 around an unconditional jump (without delay slots). If so, invert
3430 this jump and point it to the target of the second jump. We cannot
3431 do this for annulled jumps, though. Again, don't convert a jump to
3433 if (! INSN_ANNULLED_BRANCH_P (delay_jump_insn
)
3434 && any_condjump_p (delay_jump_insn
)
3435 && next
&& simplejump_or_return_p (next
)
3436 && (next_active_insn (as_a
<rtx_insn
*> (target_label
))
3437 == next_active_insn (next
))
3438 && no_labels_between_p (insn
, next
))
3440 rtx label
= JUMP_LABEL (next
);
3441 rtx old_label
= JUMP_LABEL (delay_jump_insn
);
3443 if (ANY_RETURN_P (label
))
3444 label
= find_end_label (label
);
3446 /* find_end_label can generate a new label. Check this first. */
3448 && no_labels_between_p (insn
, next
)
3449 && redirect_with_delay_slots_safe_p (delay_jump_insn
,
3452 /* Be careful how we do this to avoid deleting code or labels
3453 that are momentarily dead. See similar optimization in
3456 ++LABEL_NUSES (old_label
);
3458 if (invert_jump (delay_jump_insn
, label
, 1))
3462 /* Must update the INSN_FROM_TARGET_P bits now that
3463 the branch is reversed, so that mark_target_live_regs
3464 will handle the delay slot insn correctly. */
3465 for (i
= 1; i
< XVECLEN (PATTERN (insn
), 0); i
++)
3467 rtx slot
= XVECEXP (PATTERN (insn
), 0, i
);
3468 INSN_FROM_TARGET_P (slot
) = ! INSN_FROM_TARGET_P (slot
);
3471 delete_related_insns (next
);
3475 if (old_label
&& --LABEL_NUSES (old_label
) == 0)
3476 delete_related_insns (old_label
);
3481 /* If we own the thread opposite the way this insn branches, see if we
3482 can merge its delay slots with following insns. */
3483 if (INSN_FROM_TARGET_P (pat
->insn (1))
3484 && own_thread_p (NEXT_INSN (insn
), 0, 1))
3485 try_merge_delay_insns (insn
, next
);
3486 else if (! INSN_FROM_TARGET_P (pat
->insn (1))
3487 && own_thread_p (target_label
, target_label
, 0))
3488 try_merge_delay_insns (insn
,
3489 next_active_insn (as_a
<rtx_insn
*> (target_label
)));
3491 /* If we get here, we haven't deleted INSN. But we may have deleted
3492 NEXT, so recompute it. */
3493 next
= next_active_insn (insn
);
3498 /* Look for filled jumps to the end of function label. We can try to convert
3499 them into RETURN insns if the insns in the delay slot are valid for the
3503 make_return_insns (rtx_insn
*first
)
3506 rtx_jump_insn
*jump_insn
;
3507 rtx real_return_label
= function_return_label
;
3508 rtx real_simple_return_label
= function_simple_return_label
;
3511 /* See if there is a RETURN insn in the function other than the one we
3512 made for END_OF_FUNCTION_LABEL. If so, set up anything we can't change
3513 into a RETURN to jump to it. */
3514 for (insn
= first
; insn
; insn
= NEXT_INSN (insn
))
3515 if (JUMP_P (insn
) && ANY_RETURN_P (PATTERN (insn
)))
3517 rtx t
= get_label_before (insn
, NULL_RTX
);
3518 if (PATTERN (insn
) == ret_rtx
)
3519 real_return_label
= t
;
3521 real_simple_return_label
= t
;
3525 /* Show an extra usage of REAL_RETURN_LABEL so it won't go away if it
3526 was equal to END_OF_FUNCTION_LABEL. */
3527 if (real_return_label
)
3528 LABEL_NUSES (real_return_label
)++;
3529 if (real_simple_return_label
)
3530 LABEL_NUSES (real_simple_return_label
)++;
3532 /* Clear the list of insns to fill so we can use it. */
3533 obstack_free (&unfilled_slots_obstack
, unfilled_firstobj
);
3535 for (insn
= first
; insn
; insn
= NEXT_INSN (insn
))
3538 rtx kind
, real_label
;
3540 /* Only look at filled JUMP_INSNs that go to the end of function
3542 if (!NONJUMP_INSN_P (insn
))
3545 if (GET_CODE (PATTERN (insn
)) != SEQUENCE
)
3548 rtx_sequence
*pat
= as_a
<rtx_sequence
*> (PATTERN (insn
));
3550 if (!jump_to_label_p (pat
->insn (0)))
3553 if (JUMP_LABEL (pat
->insn (0)) == function_return_label
)
3556 real_label
= real_return_label
;
3558 else if (JUMP_LABEL (pat
->insn (0)) == function_simple_return_label
)
3560 kind
= simple_return_rtx
;
3561 real_label
= real_simple_return_label
;
3566 jump_insn
= as_a
<rtx_jump_insn
*> (pat
->insn (0));
3568 /* If we can't make the jump into a RETURN, try to redirect it to the best
3569 RETURN and go on to the next insn. */
3570 if (!reorg_redirect_jump (jump_insn
, kind
))
3572 /* Make sure redirecting the jump will not invalidate the delay
3574 if (redirect_with_delay_slots_safe_p (jump_insn
, real_label
, insn
))
3575 reorg_redirect_jump (jump_insn
, real_label
);
3579 /* See if this RETURN can accept the insns current in its delay slot.
3580 It can if it has more or an equal number of slots and the contents
3581 of each is valid. */
3583 flags
= get_jump_flags (jump_insn
, JUMP_LABEL (jump_insn
));
3584 slots
= num_delay_slots (jump_insn
);
3585 if (slots
>= XVECLEN (pat
, 0) - 1)
3587 for (i
= 1; i
< XVECLEN (pat
, 0); i
++)
3589 #if ANNUL_IFFALSE_SLOTS
3590 (INSN_ANNULLED_BRANCH_P (jump_insn
)
3591 && INSN_FROM_TARGET_P (pat
->insn (i
)))
3592 ? eligible_for_annul_false (jump_insn
, i
- 1,
3593 pat
->insn (i
), flags
) :
3595 #if ANNUL_IFTRUE_SLOTS
3596 (INSN_ANNULLED_BRANCH_P (jump_insn
)
3597 && ! INSN_FROM_TARGET_P (pat
->insn (i
)))
3598 ? eligible_for_annul_true (jump_insn
, i
- 1,
3599 pat
->insn (i
), flags
) :
3601 eligible_for_delay (jump_insn
, i
- 1,
3602 pat
->insn (i
), flags
)))
3608 if (i
== XVECLEN (pat
, 0))
3611 /* We have to do something with this insn. If it is an unconditional
3612 RETURN, delete the SEQUENCE and output the individual insns,
3613 followed by the RETURN. Then set things up so we try to find
3614 insns for its delay slots, if it needs some. */
3615 if (ANY_RETURN_P (PATTERN (jump_insn
)))
3617 rtx_insn
*prev
= PREV_INSN (insn
);
3619 delete_related_insns (insn
);
3620 for (i
= 1; i
< XVECLEN (pat
, 0); i
++)
3621 prev
= emit_insn_after (PATTERN (XVECEXP (pat
, 0, i
)), prev
);
3623 insn
= emit_jump_insn_after (PATTERN (jump_insn
), prev
);
3624 emit_barrier_after (insn
);
3627 obstack_ptr_grow (&unfilled_slots_obstack
, insn
);
3630 /* It is probably more efficient to keep this with its current
3631 delay slot as a branch to a RETURN. */
3632 reorg_redirect_jump (jump_insn
, real_label
);
3635 /* Now delete REAL_RETURN_LABEL if we never used it. Then try to fill any
3636 new delay slots we have created. */
3637 if (real_return_label
!= NULL_RTX
&& --LABEL_NUSES (real_return_label
) == 0)
3638 delete_related_insns (real_return_label
);
3639 if (real_simple_return_label
!= NULL_RTX
3640 && --LABEL_NUSES (real_simple_return_label
) == 0)
3641 delete_related_insns (real_simple_return_label
);
3643 fill_simple_delay_slots (1);
3644 fill_simple_delay_slots (0);
3647 /* Try to find insns to place in delay slots. */
3650 dbr_schedule (rtx_insn
*first
)
3652 rtx_insn
*insn
, *next
, *epilogue_insn
= 0;
3654 bool need_return_insns
;
3656 /* If the current function has no insns other than the prologue and
3657 epilogue, then do not try to fill any delay slots. */
3658 if (n_basic_blocks_for_fn (cfun
) == NUM_FIXED_BLOCKS
)
3661 /* Find the highest INSN_UID and allocate and initialize our map from
3662 INSN_UID's to position in code. */
3663 for (max_uid
= 0, insn
= first
; insn
; insn
= NEXT_INSN (insn
))
3665 if (INSN_UID (insn
) > max_uid
)
3666 max_uid
= INSN_UID (insn
);
3668 && NOTE_KIND (insn
) == NOTE_INSN_EPILOGUE_BEG
)
3669 epilogue_insn
= insn
;
3672 uid_to_ruid
= XNEWVEC (int, max_uid
+ 1);
3673 for (i
= 0, insn
= first
; insn
; i
++, insn
= NEXT_INSN (insn
))
3674 uid_to_ruid
[INSN_UID (insn
)] = i
;
3676 /* Initialize the list of insns that need filling. */
3677 if (unfilled_firstobj
== 0)
3679 gcc_obstack_init (&unfilled_slots_obstack
);
3680 unfilled_firstobj
= XOBNEWVAR (&unfilled_slots_obstack
, rtx
, 0);
3683 for (insn
= next_active_insn (first
); insn
; insn
= next_active_insn (insn
))
3687 /* Skip vector tables. We can't get attributes for them. */
3688 if (JUMP_TABLE_DATA_P (insn
))
3692 INSN_ANNULLED_BRANCH_P (insn
) = 0;
3693 INSN_FROM_TARGET_P (insn
) = 0;
3695 if (num_delay_slots (insn
) > 0)
3696 obstack_ptr_grow (&unfilled_slots_obstack
, insn
);
3698 /* Ensure all jumps go to the last of a set of consecutive labels. */
3700 && (condjump_p (insn
) || condjump_in_parallel_p (insn
))
3701 && !ANY_RETURN_P (JUMP_LABEL (insn
))
3702 && ((target
= skip_consecutive_labels (JUMP_LABEL (insn
)))
3703 != JUMP_LABEL (insn
)))
3704 redirect_jump (as_a
<rtx_jump_insn
*> (insn
), target
, 1);
3707 init_resource_info (epilogue_insn
);
3709 /* Show we haven't computed an end-of-function label yet. */
3710 function_return_label
= function_simple_return_label
= NULL
;
3712 /* Initialize the statistics for this function. */
3713 memset (num_insns_needing_delays
, 0, sizeof num_insns_needing_delays
);
3714 memset (num_filled_delays
, 0, sizeof num_filled_delays
);
3716 /* Now do the delay slot filling. Try everything twice in case earlier
3717 changes make more slots fillable. */
3719 for (reorg_pass_number
= 0;
3720 reorg_pass_number
< MAX_REORG_PASSES
;
3721 reorg_pass_number
++)
3723 fill_simple_delay_slots (1);
3724 fill_simple_delay_slots (0);
3725 if (!targetm
.no_speculation_in_delay_slots_p ())
3726 fill_eager_delay_slots ();
3727 relax_delay_slots (first
);
3730 /* If we made an end of function label, indicate that it is now
3731 safe to delete it by undoing our prior adjustment to LABEL_NUSES.
3732 If it is now unused, delete it. */
3733 if (function_return_label
&& --LABEL_NUSES (function_return_label
) == 0)
3734 delete_related_insns (function_return_label
);
3735 if (function_simple_return_label
3736 && --LABEL_NUSES (function_simple_return_label
) == 0)
3737 delete_related_insns (function_simple_return_label
);
3739 need_return_insns
= false;
3740 need_return_insns
|= targetm
.have_return () && function_return_label
!= 0;
3741 need_return_insns
|= (targetm
.have_simple_return ()
3742 && function_simple_return_label
!= 0);
3743 if (need_return_insns
)
3744 make_return_insns (first
);
3746 /* Delete any USE insns made by update_block; subsequent passes don't need
3747 them or know how to deal with them. */
3748 for (insn
= first
; insn
; insn
= next
)
3750 next
= NEXT_INSN (insn
);
3752 if (NONJUMP_INSN_P (insn
) && GET_CODE (PATTERN (insn
)) == USE
3753 && INSN_P (XEXP (PATTERN (insn
), 0)))
3754 next
= delete_related_insns (insn
);
3757 obstack_free (&unfilled_slots_obstack
, unfilled_firstobj
);
3759 /* It is not clear why the line below is needed, but it does seem to be. */
3760 unfilled_firstobj
= XOBNEWVAR (&unfilled_slots_obstack
, rtx
, 0);
3764 int i
, j
, need_comma
;
3765 int total_delay_slots
[MAX_DELAY_HISTOGRAM
+ 1];
3766 int total_annul_slots
[MAX_DELAY_HISTOGRAM
+ 1];
3768 for (reorg_pass_number
= 0;
3769 reorg_pass_number
< MAX_REORG_PASSES
;
3770 reorg_pass_number
++)
3772 fprintf (dump_file
, ";; Reorg pass #%d:\n", reorg_pass_number
+ 1);
3773 for (i
= 0; i
< NUM_REORG_FUNCTIONS
; i
++)
3776 fprintf (dump_file
, ";; Reorg function #%d\n", i
);
3778 fprintf (dump_file
, ";; %d insns needing delay slots\n;; ",
3779 num_insns_needing_delays
[i
][reorg_pass_number
]);
3781 for (j
= 0; j
< MAX_DELAY_HISTOGRAM
+ 1; j
++)
3782 if (num_filled_delays
[i
][j
][reorg_pass_number
])
3785 fprintf (dump_file
, ", ");
3787 fprintf (dump_file
, "%d got %d delays",
3788 num_filled_delays
[i
][j
][reorg_pass_number
], j
);
3790 fprintf (dump_file
, "\n");
3793 memset (total_delay_slots
, 0, sizeof total_delay_slots
);
3794 memset (total_annul_slots
, 0, sizeof total_annul_slots
);
3795 for (insn
= first
; insn
; insn
= NEXT_INSN (insn
))
3797 if (! insn
->deleted ()
3798 && NONJUMP_INSN_P (insn
)
3799 && GET_CODE (PATTERN (insn
)) != USE
3800 && GET_CODE (PATTERN (insn
)) != CLOBBER
)
3802 if (GET_CODE (PATTERN (insn
)) == SEQUENCE
)
3805 j
= XVECLEN (PATTERN (insn
), 0) - 1;
3806 if (j
> MAX_DELAY_HISTOGRAM
)
3807 j
= MAX_DELAY_HISTOGRAM
;
3808 control
= XVECEXP (PATTERN (insn
), 0, 0);
3809 if (JUMP_P (control
) && INSN_ANNULLED_BRANCH_P (control
))
3810 total_annul_slots
[j
]++;
3812 total_delay_slots
[j
]++;
3814 else if (num_delay_slots (insn
) > 0)
3815 total_delay_slots
[0]++;
3818 fprintf (dump_file
, ";; Reorg totals: ");
3820 for (j
= 0; j
< MAX_DELAY_HISTOGRAM
+ 1; j
++)
3822 if (total_delay_slots
[j
])
3825 fprintf (dump_file
, ", ");
3827 fprintf (dump_file
, "%d got %d delays", total_delay_slots
[j
], j
);
3830 fprintf (dump_file
, "\n");
3832 if (ANNUL_IFTRUE_SLOTS
|| ANNUL_IFFALSE_SLOTS
)
3834 fprintf (dump_file
, ";; Reorg annuls: ");
3836 for (j
= 0; j
< MAX_DELAY_HISTOGRAM
+ 1; j
++)
3838 if (total_annul_slots
[j
])
3841 fprintf (dump_file
, ", ");
3843 fprintf (dump_file
, "%d got %d delays", total_annul_slots
[j
], j
);
3846 fprintf (dump_file
, "\n");
3849 fprintf (dump_file
, "\n");
3852 if (!sibling_labels
.is_empty ())
3854 update_alignments (sibling_labels
);
3855 sibling_labels
.release ();
3858 free_resource_info ();
3860 crtl
->dbr_scheduled_p
= true;
3863 /* Run delay slot optimization. */
3865 rest_of_handle_delay_slots (void)
3868 dbr_schedule (get_insns ());
3875 const pass_data pass_data_delay_slots
=
3877 RTL_PASS
, /* type */
3879 OPTGROUP_NONE
, /* optinfo_flags */
3880 TV_DBR_SCHED
, /* tv_id */
3881 0, /* properties_required */
3882 0, /* properties_provided */
3883 0, /* properties_destroyed */
3884 0, /* todo_flags_start */
3885 0, /* todo_flags_finish */
3888 class pass_delay_slots
: public rtl_opt_pass
3891 pass_delay_slots (gcc::context
*ctxt
)
3892 : rtl_opt_pass (pass_data_delay_slots
, ctxt
)
3895 /* opt_pass methods: */
3896 virtual bool gate (function
*);
3897 virtual unsigned int execute (function
*)
3899 return rest_of_handle_delay_slots ();
3902 }; // class pass_delay_slots
3905 pass_delay_slots::gate (function
*)
3907 /* At -O0 dataflow info isn't updated after RA. */
3909 return optimize
> 0 && flag_delayed_branch
&& !crtl
->dbr_scheduled_p
;
3917 make_pass_delay_slots (gcc::context
*ctxt
)
3919 return new pass_delay_slots (ctxt
);
3922 /* Machine dependent reorg pass. */
3926 const pass_data pass_data_machine_reorg
=
3928 RTL_PASS
, /* type */
3930 OPTGROUP_NONE
, /* optinfo_flags */
3931 TV_MACH_DEP
, /* tv_id */
3932 0, /* properties_required */
3933 0, /* properties_provided */
3934 0, /* properties_destroyed */
3935 0, /* todo_flags_start */
3936 0, /* todo_flags_finish */
3939 class pass_machine_reorg
: public rtl_opt_pass
3942 pass_machine_reorg (gcc::context
*ctxt
)
3943 : rtl_opt_pass (pass_data_machine_reorg
, ctxt
)
3946 /* opt_pass methods: */
3947 virtual bool gate (function
*)
3949 return targetm
.machine_dependent_reorg
!= 0;
3952 virtual unsigned int execute (function
*)
3954 targetm
.machine_dependent_reorg ();
3958 }; // class pass_machine_reorg
3963 make_pass_machine_reorg (gcc::context
*ctxt
)
3965 return new pass_machine_reorg (ctxt
);