1 /* Definitions for computing resource usage of specific insns.
2 Copyright (C) 1999-2015 Free Software Foundation, Inc.
4 This file is part of GCC.
6 GCC is free software; you can redistribute it and/or modify it under
7 the terms of the GNU General Public License as published by the Free
8 Software Foundation; either version 3, or (at your option) any later
11 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
12 WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
16 You should have received a copy of the GNU General Public License
17 along with GCC; see the file COPYING3. If not see
18 <http://www.gnu.org/licenses/>. */
22 #include "coretypes.h"
24 #include "diagnostic-core.h"
27 #include "hard-reg-set.h"
37 #include "dominance.h"
40 #include "basic-block.h"
43 #include "insn-attr.h"
47 /* This structure is used to record liveness information at the targets or
48 fallthrough insns of branches. We will most likely need the information
49 at targets again, so save them in a hash table rather than recomputing them
54 int uid
; /* INSN_UID of target. */
55 struct target_info
*next
; /* Next info for same hash bucket. */
56 HARD_REG_SET live_regs
; /* Registers live at target. */
57 int block
; /* Basic block number containing target. */
58 int bb_tick
; /* Generation count of basic block info. */
61 #define TARGET_HASH_PRIME 257
63 /* Indicates what resources are required at the beginning of the epilogue. */
64 static struct resources start_of_epilogue_needs
;
66 /* Indicates what resources are required at function end. */
67 static struct resources end_of_function_needs
;
69 /* Define the hash table itself. */
70 static struct target_info
**target_hash_table
= NULL
;
72 /* For each basic block, we maintain a generation number of its basic
73 block info, which is updated each time we move an insn from the
74 target of a jump. This is the generation number indexed by block
79 /* Marks registers possibly live at the current place being scanned by
80 mark_target_live_regs. Also used by update_live_status. */
82 static HARD_REG_SET current_live_regs
;
84 /* Marks registers for which we have seen a REG_DEAD note but no assignment.
85 Also only used by the next two functions. */
87 static HARD_REG_SET pending_dead_regs
;
89 static void update_live_status (rtx
, const_rtx
, void *);
90 static int find_basic_block (rtx_insn
*, int);
91 static rtx_insn
*next_insn_no_annul (rtx_insn
*);
92 static rtx_insn
*find_dead_or_set_registers (rtx_insn
*, struct resources
*,
93 rtx
*, int, struct resources
,
96 /* Utility function called from mark_target_live_regs via note_stores.
97 It deadens any CLOBBERed registers and livens any SET registers. */
100 update_live_status (rtx dest
, const_rtx x
, void *data ATTRIBUTE_UNUSED
)
102 int first_regno
, last_regno
;
106 && (GET_CODE (dest
) != SUBREG
|| !REG_P (SUBREG_REG (dest
))))
109 if (GET_CODE (dest
) == SUBREG
)
111 first_regno
= subreg_regno (dest
);
112 last_regno
= first_regno
+ subreg_nregs (dest
);
117 first_regno
= REGNO (dest
);
118 last_regno
= END_HARD_REGNO (dest
);
121 if (GET_CODE (x
) == CLOBBER
)
122 for (i
= first_regno
; i
< last_regno
; i
++)
123 CLEAR_HARD_REG_BIT (current_live_regs
, i
);
125 for (i
= first_regno
; i
< last_regno
; i
++)
127 SET_HARD_REG_BIT (current_live_regs
, i
);
128 CLEAR_HARD_REG_BIT (pending_dead_regs
, i
);
132 /* Find the number of the basic block with correct live register
133 information that starts closest to INSN. Return -1 if we couldn't
134 find such a basic block or the beginning is more than
135 SEARCH_LIMIT instructions before INSN. Use SEARCH_LIMIT = -1 for
138 The delay slot filling code destroys the control-flow graph so,
139 instead of finding the basic block containing INSN, we search
140 backwards toward a BARRIER where the live register information is
144 find_basic_block (rtx_insn
*insn
, int search_limit
)
146 /* Scan backwards to the previous BARRIER. Then see if we can find a
147 label that starts a basic block. Return the basic block number. */
148 for (insn
= prev_nonnote_insn (insn
);
149 insn
&& !BARRIER_P (insn
) && search_limit
!= 0;
150 insn
= prev_nonnote_insn (insn
), --search_limit
)
153 /* The closest BARRIER is too far away. */
154 if (search_limit
== 0)
157 /* The start of the function. */
159 return ENTRY_BLOCK_PTR_FOR_FN (cfun
)->next_bb
->index
;
161 /* See if any of the upcoming CODE_LABELs start a basic block. If we reach
162 anything other than a CODE_LABEL or note, we can't find this code. */
163 for (insn
= next_nonnote_insn (insn
);
164 insn
&& LABEL_P (insn
);
165 insn
= next_nonnote_insn (insn
))
166 if (BLOCK_FOR_INSN (insn
))
167 return BLOCK_FOR_INSN (insn
)->index
;
172 /* Similar to next_insn, but ignores insns in the delay slots of
173 an annulled branch. */
176 next_insn_no_annul (rtx_insn
*insn
)
180 /* If INSN is an annulled branch, skip any insns from the target
183 && INSN_ANNULLED_BRANCH_P (insn
)
184 && NEXT_INSN (PREV_INSN (insn
)) != insn
)
186 rtx_insn
*next
= NEXT_INSN (insn
);
188 while ((NONJUMP_INSN_P (next
) || JUMP_P (next
) || CALL_P (next
))
189 && INSN_FROM_TARGET_P (next
))
192 next
= NEXT_INSN (insn
);
196 insn
= NEXT_INSN (insn
);
197 if (insn
&& NONJUMP_INSN_P (insn
)
198 && GET_CODE (PATTERN (insn
)) == SEQUENCE
)
199 insn
= as_a
<rtx_sequence
*> (PATTERN (insn
))->insn (0);
205 /* Given X, some rtl, and RES, a pointer to a `struct resource', mark
206 which resources are referenced by the insn. If INCLUDE_DELAYED_EFFECTS
207 is TRUE, resources used by the called routine will be included for
211 mark_referenced_resources (rtx x
, struct resources
*res
,
212 bool include_delayed_effects
)
214 enum rtx_code code
= GET_CODE (x
);
217 const char *format_ptr
;
219 /* Handle leaf items for which we set resource flags. Also, special-case
220 CALL, SET and CLOBBER operators. */
231 if (!REG_P (SUBREG_REG (x
)))
232 mark_referenced_resources (SUBREG_REG (x
), res
, false);
235 unsigned int regno
= subreg_regno (x
);
236 unsigned int last_regno
= regno
+ subreg_nregs (x
);
238 gcc_assert (last_regno
<= FIRST_PSEUDO_REGISTER
);
239 for (r
= regno
; r
< last_regno
; r
++)
240 SET_HARD_REG_BIT (res
->regs
, r
);
245 gcc_assert (HARD_REGISTER_P (x
));
246 add_to_hard_reg_set (&res
->regs
, GET_MODE (x
), REGNO (x
));
250 /* If this memory shouldn't change, it really isn't referencing
252 if (! MEM_READONLY_P (x
))
254 res
->volatil
|= MEM_VOLATILE_P (x
);
256 /* Mark registers used to access memory. */
257 mark_referenced_resources (XEXP (x
, 0), res
, false);
264 case UNSPEC_VOLATILE
:
267 /* Traditional asm's are always volatile. */
272 res
->volatil
|= MEM_VOLATILE_P (x
);
274 /* For all ASM_OPERANDS, we must traverse the vector of input operands.
275 We can not just fall through here since then we would be confused
276 by the ASM_INPUT rtx inside ASM_OPERANDS, which do not indicate
277 traditional asms unlike their normal usage. */
279 for (i
= 0; i
< ASM_OPERANDS_INPUT_LENGTH (x
); i
++)
280 mark_referenced_resources (ASM_OPERANDS_INPUT (x
, i
), res
, false);
284 /* The first operand will be a (MEM (xxx)) but doesn't really reference
285 memory. The second operand may be referenced, though. */
286 mark_referenced_resources (XEXP (XEXP (x
, 0), 0), res
, false);
287 mark_referenced_resources (XEXP (x
, 1), res
, false);
291 /* Usually, the first operand of SET is set, not referenced. But
292 registers used to access memory are referenced. SET_DEST is
293 also referenced if it is a ZERO_EXTRACT. */
295 mark_referenced_resources (SET_SRC (x
), res
, false);
298 if (GET_CODE (x
) == ZERO_EXTRACT
299 || GET_CODE (x
) == STRICT_LOW_PART
)
300 mark_referenced_resources (x
, res
, false);
301 else if (GET_CODE (x
) == SUBREG
)
304 mark_referenced_resources (XEXP (x
, 0), res
, false);
311 if (include_delayed_effects
)
313 /* A CALL references memory, the frame pointer if it exists, the
314 stack pointer, any global registers and any registers given in
315 USE insns immediately in front of the CALL.
317 However, we may have moved some of the parameter loading insns
318 into the delay slot of this CALL. If so, the USE's for them
319 don't count and should be skipped. */
320 rtx_insn
*insn
= PREV_INSN (as_a
<rtx_insn
*> (x
));
321 rtx_sequence
*sequence
= 0;
325 /* If we are part of a delay slot sequence, point at the SEQUENCE. */
326 if (NEXT_INSN (insn
) != x
)
328 sequence
= as_a
<rtx_sequence
*> (PATTERN (NEXT_INSN (insn
)));
329 seq_size
= sequence
->len ();
330 gcc_assert (GET_CODE (sequence
) == SEQUENCE
);
334 SET_HARD_REG_BIT (res
->regs
, STACK_POINTER_REGNUM
);
335 if (frame_pointer_needed
)
337 SET_HARD_REG_BIT (res
->regs
, FRAME_POINTER_REGNUM
);
338 if (!HARD_FRAME_POINTER_IS_FRAME_POINTER
)
339 SET_HARD_REG_BIT (res
->regs
, HARD_FRAME_POINTER_REGNUM
);
342 for (i
= 0; i
< FIRST_PSEUDO_REGISTER
; i
++)
344 SET_HARD_REG_BIT (res
->regs
, i
);
346 /* Check for a REG_SETJMP. If it exists, then we must
347 assume that this call can need any register.
349 This is done to be more conservative about how we handle setjmp.
350 We assume that they both use and set all registers. Using all
351 registers ensures that a register will not be considered dead
352 just because it crosses a setjmp call. A register should be
353 considered dead only if the setjmp call returns nonzero. */
354 if (find_reg_note (x
, REG_SETJMP
, NULL
))
355 SET_HARD_REG_SET (res
->regs
);
360 for (link
= CALL_INSN_FUNCTION_USAGE (x
);
362 link
= XEXP (link
, 1))
363 if (GET_CODE (XEXP (link
, 0)) == USE
)
365 for (i
= 1; i
< seq_size
; i
++)
367 rtx slot_pat
= PATTERN (sequence
->element (i
));
368 if (GET_CODE (slot_pat
) == SET
369 && rtx_equal_p (SET_DEST (slot_pat
),
370 XEXP (XEXP (link
, 0), 0)))
374 mark_referenced_resources (XEXP (XEXP (link
, 0), 0),
380 /* ... fall through to other INSN processing ... */
385 if (GET_CODE (PATTERN (x
)) == COND_EXEC
)
386 /* In addition to the usual references, also consider all outputs
387 as referenced, to compensate for mark_set_resources treating
388 them as killed. This is similar to ZERO_EXTRACT / STRICT_LOW_PART
389 handling, execpt that we got a partial incidence instead of a partial
391 mark_set_resources (x
, res
, 0,
392 include_delayed_effects
393 ? MARK_SRC_DEST_CALL
: MARK_SRC_DEST
);
395 if (! include_delayed_effects
396 && INSN_REFERENCES_ARE_DELAYED (as_a
<rtx_insn
*> (x
)))
399 /* No special processing, just speed up. */
400 mark_referenced_resources (PATTERN (x
), res
, include_delayed_effects
);
407 /* Process each sub-expression and flag what it needs. */
408 format_ptr
= GET_RTX_FORMAT (code
);
409 for (i
= 0; i
< GET_RTX_LENGTH (code
); i
++)
410 switch (*format_ptr
++)
413 mark_referenced_resources (XEXP (x
, i
), res
, include_delayed_effects
);
417 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
418 mark_referenced_resources (XVECEXP (x
, i
, j
), res
,
419 include_delayed_effects
);
424 /* A subroutine of mark_target_live_regs. Search forward from TARGET
425 looking for registers that are set before they are used. These are dead.
426 Stop after passing a few conditional jumps, and/or a small
427 number of unconditional branches. */
430 find_dead_or_set_registers (rtx_insn
*target
, struct resources
*res
,
431 rtx
*jump_target
, int jump_count
,
432 struct resources set
, struct resources needed
)
434 HARD_REG_SET scratch
;
437 rtx_insn
*jump_insn
= 0;
440 for (insn
= target
; insn
; insn
= next_insn
)
442 rtx_insn
*this_jump_insn
= insn
;
444 next_insn
= NEXT_INSN (insn
);
446 /* If this instruction can throw an exception, then we don't
447 know where we might end up next. That means that we have to
448 assume that whatever we have already marked as live really is
450 if (can_throw_internal (insn
))
453 switch (GET_CODE (insn
))
456 /* After a label, any pending dead registers that weren't yet
457 used can be made dead. */
458 AND_COMPL_HARD_REG_SET (pending_dead_regs
, needed
.regs
);
459 AND_COMPL_HARD_REG_SET (res
->regs
, pending_dead_regs
);
460 CLEAR_HARD_REG_SET (pending_dead_regs
);
469 if (GET_CODE (PATTERN (insn
)) == USE
)
471 /* If INSN is a USE made by update_block, we care about the
472 underlying insn. Any registers set by the underlying insn
473 are live since the insn is being done somewhere else. */
474 if (INSN_P (XEXP (PATTERN (insn
), 0)))
475 mark_set_resources (XEXP (PATTERN (insn
), 0), res
, 0,
478 /* All other USE insns are to be ignored. */
481 else if (GET_CODE (PATTERN (insn
)) == CLOBBER
)
483 else if (rtx_sequence
*seq
=
484 dyn_cast
<rtx_sequence
*> (PATTERN (insn
)))
486 /* An unconditional jump can be used to fill the delay slot
487 of a call, so search for a JUMP_INSN in any position. */
488 for (i
= 0; i
< seq
->len (); i
++)
490 this_jump_insn
= seq
->insn (i
);
491 if (JUMP_P (this_jump_insn
))
500 if (JUMP_P (this_jump_insn
))
502 if (jump_count
++ < 10)
504 if (any_uncondjump_p (this_jump_insn
)
505 || ANY_RETURN_P (PATTERN (this_jump_insn
)))
507 rtx lab_or_return
= JUMP_LABEL (this_jump_insn
);
508 if (ANY_RETURN_P (lab_or_return
))
511 next_insn
= as_a
<rtx_insn
*> (lab_or_return
);
516 *jump_target
= JUMP_LABEL (this_jump_insn
);
519 else if (any_condjump_p (this_jump_insn
))
521 struct resources target_set
, target_res
;
522 struct resources fallthrough_res
;
524 /* We can handle conditional branches here by following
525 both paths, and then IOR the results of the two paths
526 together, which will give us registers that are dead
527 on both paths. Since this is expensive, we give it
528 a much higher cost than unconditional branches. The
529 cost was chosen so that we will follow at most 1
530 conditional branch. */
533 if (jump_count
>= 10)
536 mark_referenced_resources (insn
, &needed
, true);
538 /* For an annulled branch, mark_set_resources ignores slots
539 filled by instructions from the target. This is correct
540 if the branch is not taken. Since we are following both
541 paths from the branch, we must also compute correct info
542 if the branch is taken. We do this by inverting all of
543 the INSN_FROM_TARGET_P bits, calling mark_set_resources,
544 and then inverting the INSN_FROM_TARGET_P bits again. */
546 if (GET_CODE (PATTERN (insn
)) == SEQUENCE
547 && INSN_ANNULLED_BRANCH_P (this_jump_insn
))
549 rtx_sequence
*seq
= as_a
<rtx_sequence
*> (PATTERN (insn
));
550 for (i
= 1; i
< seq
->len (); i
++)
551 INSN_FROM_TARGET_P (seq
->element (i
))
552 = ! INSN_FROM_TARGET_P (seq
->element (i
));
555 mark_set_resources (insn
, &target_set
, 0,
558 for (i
= 1; i
< seq
->len (); i
++)
559 INSN_FROM_TARGET_P (seq
->element (i
))
560 = ! INSN_FROM_TARGET_P (seq
->element (i
));
562 mark_set_resources (insn
, &set
, 0, MARK_SRC_DEST_CALL
);
566 mark_set_resources (insn
, &set
, 0, MARK_SRC_DEST_CALL
);
571 COPY_HARD_REG_SET (scratch
, target_set
.regs
);
572 AND_COMPL_HARD_REG_SET (scratch
, needed
.regs
);
573 AND_COMPL_HARD_REG_SET (target_res
.regs
, scratch
);
575 fallthrough_res
= *res
;
576 COPY_HARD_REG_SET (scratch
, set
.regs
);
577 AND_COMPL_HARD_REG_SET (scratch
, needed
.regs
);
578 AND_COMPL_HARD_REG_SET (fallthrough_res
.regs
, scratch
);
580 if (!ANY_RETURN_P (JUMP_LABEL (this_jump_insn
)))
581 find_dead_or_set_registers (JUMP_LABEL_AS_INSN (this_jump_insn
),
582 &target_res
, 0, jump_count
,
584 find_dead_or_set_registers (next_insn
,
585 &fallthrough_res
, 0, jump_count
,
587 IOR_HARD_REG_SET (fallthrough_res
.regs
, target_res
.regs
);
588 AND_HARD_REG_SET (res
->regs
, fallthrough_res
.regs
);
596 /* Don't try this optimization if we expired our jump count
597 above, since that would mean there may be an infinite loop
598 in the function being compiled. */
604 mark_referenced_resources (insn
, &needed
, true);
605 mark_set_resources (insn
, &set
, 0, MARK_SRC_DEST_CALL
);
607 COPY_HARD_REG_SET (scratch
, set
.regs
);
608 AND_COMPL_HARD_REG_SET (scratch
, needed
.regs
);
609 AND_COMPL_HARD_REG_SET (res
->regs
, scratch
);
615 /* Given X, a part of an insn, and a pointer to a `struct resource',
616 RES, indicate which resources are modified by the insn. If
617 MARK_TYPE is MARK_SRC_DEST_CALL, also mark resources potentially
618 set by the called routine.
620 If IN_DEST is nonzero, it means we are inside a SET. Otherwise,
621 objects are being referenced instead of set.
623 We never mark the insn as modifying the condition code unless it explicitly
624 SETs CC0 even though this is not totally correct. The reason for this is
625 that we require a SET of CC0 to immediately precede the reference to CC0.
626 So if some other insn sets CC0 as a side-effect, we know it cannot affect
627 our computation and thus may be placed in a delay slot. */
630 mark_set_resources (rtx x
, struct resources
*res
, int in_dest
,
631 enum mark_resource_type mark_type
)
636 const char *format_ptr
;
653 /* These don't set any resources. */
662 /* Called routine modifies the condition code, memory, any registers
663 that aren't saved across calls, global registers and anything
664 explicitly CLOBBERed immediately after the CALL_INSN. */
666 if (mark_type
== MARK_SRC_DEST_CALL
)
668 rtx_call_insn
*call_insn
= as_a
<rtx_call_insn
*> (x
);
672 res
->cc
= res
->memory
= 1;
674 get_call_reg_set_usage (call_insn
, ®s
, regs_invalidated_by_call
);
675 IOR_HARD_REG_SET (res
->regs
, regs
);
677 for (link
= CALL_INSN_FUNCTION_USAGE (call_insn
);
678 link
; link
= XEXP (link
, 1))
679 if (GET_CODE (XEXP (link
, 0)) == CLOBBER
)
680 mark_set_resources (SET_DEST (XEXP (link
, 0)), res
, 1,
683 /* Check for a REG_SETJMP. If it exists, then we must
684 assume that this call can clobber any register. */
685 if (find_reg_note (call_insn
, REG_SETJMP
, NULL
))
686 SET_HARD_REG_SET (res
->regs
);
689 /* ... and also what its RTL says it modifies, if anything. */
694 /* An insn consisting of just a CLOBBER (or USE) is just for flow
695 and doesn't actually do anything, so we ignore it. */
697 if (mark_type
!= MARK_SRC_DEST_CALL
698 && INSN_SETS_ARE_DELAYED (as_a
<rtx_insn
*> (x
)))
702 if (GET_CODE (x
) != USE
&& GET_CODE (x
) != CLOBBER
)
707 /* If the source of a SET is a CALL, this is actually done by
708 the called routine. So only include it if we are to include the
709 effects of the calling routine. */
711 mark_set_resources (SET_DEST (x
), res
,
712 (mark_type
== MARK_SRC_DEST_CALL
713 || GET_CODE (SET_SRC (x
)) != CALL
),
716 mark_set_resources (SET_SRC (x
), res
, 0, MARK_SRC_DEST
);
720 mark_set_resources (XEXP (x
, 0), res
, 1, MARK_SRC_DEST
);
725 rtx_sequence
*seq
= as_a
<rtx_sequence
*> (x
);
726 rtx control
= seq
->element (0);
727 bool annul_p
= JUMP_P (control
) && INSN_ANNULLED_BRANCH_P (control
);
729 mark_set_resources (control
, res
, 0, mark_type
);
730 for (i
= seq
->len () - 1; i
>= 0; --i
)
732 rtx elt
= seq
->element (i
);
733 if (!annul_p
&& INSN_FROM_TARGET_P (elt
))
734 mark_set_resources (elt
, res
, 0, mark_type
);
743 mark_set_resources (XEXP (x
, 0), res
, 1, MARK_SRC_DEST
);
748 mark_set_resources (XEXP (x
, 0), res
, 1, MARK_SRC_DEST
);
749 mark_set_resources (XEXP (XEXP (x
, 1), 0), res
, 0, MARK_SRC_DEST
);
750 mark_set_resources (XEXP (XEXP (x
, 1), 1), res
, 0, MARK_SRC_DEST
);
755 mark_set_resources (XEXP (x
, 0), res
, in_dest
, MARK_SRC_DEST
);
756 mark_set_resources (XEXP (x
, 1), res
, 0, MARK_SRC_DEST
);
757 mark_set_resources (XEXP (x
, 2), res
, 0, MARK_SRC_DEST
);
764 res
->volatil
|= MEM_VOLATILE_P (x
);
767 mark_set_resources (XEXP (x
, 0), res
, 0, MARK_SRC_DEST
);
773 if (!REG_P (SUBREG_REG (x
)))
774 mark_set_resources (SUBREG_REG (x
), res
, in_dest
, mark_type
);
777 unsigned int regno
= subreg_regno (x
);
778 unsigned int last_regno
= regno
+ subreg_nregs (x
);
780 gcc_assert (last_regno
<= FIRST_PSEUDO_REGISTER
);
781 for (r
= regno
; r
< last_regno
; r
++)
782 SET_HARD_REG_BIT (res
->regs
, r
);
790 gcc_assert (HARD_REGISTER_P (x
));
791 add_to_hard_reg_set (&res
->regs
, GET_MODE (x
), REGNO (x
));
795 case UNSPEC_VOLATILE
:
797 /* Traditional asm's are always volatile. */
806 res
->volatil
|= MEM_VOLATILE_P (x
);
808 /* For all ASM_OPERANDS, we must traverse the vector of input operands.
809 We can not just fall through here since then we would be confused
810 by the ASM_INPUT rtx inside ASM_OPERANDS, which do not indicate
811 traditional asms unlike their normal usage. */
813 for (i
= 0; i
< ASM_OPERANDS_INPUT_LENGTH (x
); i
++)
814 mark_set_resources (ASM_OPERANDS_INPUT (x
, i
), res
, in_dest
,
822 /* Process each sub-expression and flag what it needs. */
823 format_ptr
= GET_RTX_FORMAT (code
);
824 for (i
= 0; i
< GET_RTX_LENGTH (code
); i
++)
825 switch (*format_ptr
++)
828 mark_set_resources (XEXP (x
, i
), res
, in_dest
, mark_type
);
832 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
833 mark_set_resources (XVECEXP (x
, i
, j
), res
, in_dest
, mark_type
);
838 /* Return TRUE if INSN is a return, possibly with a filled delay slot. */
841 return_insn_p (const_rtx insn
)
843 if (JUMP_P (insn
) && ANY_RETURN_P (PATTERN (insn
)))
846 if (NONJUMP_INSN_P (insn
) && GET_CODE (PATTERN (insn
)) == SEQUENCE
)
847 return return_insn_p (XVECEXP (PATTERN (insn
), 0, 0));
852 /* Set the resources that are live at TARGET.
854 If TARGET is zero, we refer to the end of the current function and can
855 return our precomputed value.
857 Otherwise, we try to find out what is live by consulting the basic block
858 information. This is tricky, because we must consider the actions of
859 reload and jump optimization, which occur after the basic block information
862 Accordingly, we proceed as follows::
864 We find the previous BARRIER and look at all immediately following labels
865 (with no intervening active insns) to see if any of them start a basic
866 block. If we hit the start of the function first, we use block 0.
868 Once we have found a basic block and a corresponding first insn, we can
869 accurately compute the live status (by starting at a label following a
870 BARRIER, we are immune to actions taken by reload and jump.) Then we
871 scan all insns between that point and our target. For each CLOBBER (or
872 for call-clobbered regs when we pass a CALL_INSN), mark the appropriate
873 registers are dead. For a SET, mark them as live.
875 We have to be careful when using REG_DEAD notes because they are not
876 updated by such things as find_equiv_reg. So keep track of registers
877 marked as dead that haven't been assigned to, and mark them dead at the
878 next CODE_LABEL since reload and jump won't propagate values across labels.
880 If we cannot find the start of a basic block (should be a very rare
881 case, if it can happen at all), mark everything as potentially live.
883 Next, scan forward from TARGET looking for things set or clobbered
884 before they are used. These are not live.
886 Because we can be called many times on the same target, save our results
887 in a hash table indexed by INSN_UID. This is only done if the function
888 init_resource_info () was invoked before we are called. */
891 mark_target_live_regs (rtx_insn
*insns
, rtx target_maybe_return
, struct resources
*res
)
895 struct target_info
*tinfo
= NULL
;
899 HARD_REG_SET scratch
;
900 struct resources set
, needed
;
902 /* Handle end of function. */
903 if (target_maybe_return
== 0 || ANY_RETURN_P (target_maybe_return
))
905 *res
= end_of_function_needs
;
909 /* We've handled the case of RETURN/SIMPLE_RETURN; we should now have an
911 rtx_insn
*target
= as_a
<rtx_insn
*> (target_maybe_return
);
913 /* Handle return insn. */
914 if (return_insn_p (target
))
916 *res
= end_of_function_needs
;
917 mark_referenced_resources (target
, res
, false);
921 /* We have to assume memory is needed, but the CC isn't. */
926 /* See if we have computed this value already. */
927 if (target_hash_table
!= NULL
)
929 for (tinfo
= target_hash_table
[INSN_UID (target
) % TARGET_HASH_PRIME
];
930 tinfo
; tinfo
= tinfo
->next
)
931 if (tinfo
->uid
== INSN_UID (target
))
934 /* Start by getting the basic block number. If we have saved
935 information, we can get it from there unless the insn at the
936 start of the basic block has been deleted. */
937 if (tinfo
&& tinfo
->block
!= -1
938 && ! BB_HEAD (BASIC_BLOCK_FOR_FN (cfun
, tinfo
->block
))->deleted ())
943 b
= find_basic_block (target
, MAX_DELAY_SLOT_LIVE_SEARCH
);
945 if (target_hash_table
!= NULL
)
949 /* If the information is up-to-date, use it. Otherwise, we will
951 if (b
== tinfo
->block
&& b
!= -1 && tinfo
->bb_tick
== bb_ticks
[b
])
953 COPY_HARD_REG_SET (res
->regs
, tinfo
->live_regs
);
959 /* Allocate a place to put our results and chain it into the
961 tinfo
= XNEW (struct target_info
);
962 tinfo
->uid
= INSN_UID (target
);
965 = target_hash_table
[INSN_UID (target
) % TARGET_HASH_PRIME
];
966 target_hash_table
[INSN_UID (target
) % TARGET_HASH_PRIME
] = tinfo
;
970 CLEAR_HARD_REG_SET (pending_dead_regs
);
972 /* If we found a basic block, get the live registers from it and update
973 them with anything set or killed between its start and the insn before
974 TARGET; this custom life analysis is really about registers so we need
975 to use the LR problem. Otherwise, we must assume everything is live. */
978 regset regs_live
= DF_LR_IN (BASIC_BLOCK_FOR_FN (cfun
, b
));
979 rtx_insn
*start_insn
, *stop_insn
;
981 /* Compute hard regs live at start of block. */
982 REG_SET_TO_HARD_REG_SET (current_live_regs
, regs_live
);
984 /* Get starting and ending insn, handling the case where each might
986 start_insn
= (b
== ENTRY_BLOCK_PTR_FOR_FN (cfun
)->next_bb
->index
?
987 insns
: BB_HEAD (BASIC_BLOCK_FOR_FN (cfun
, b
)));
990 if (NONJUMP_INSN_P (start_insn
)
991 && GET_CODE (PATTERN (start_insn
)) == SEQUENCE
)
992 start_insn
= as_a
<rtx_sequence
*> (PATTERN (start_insn
))->insn (0);
994 if (NONJUMP_INSN_P (stop_insn
)
995 && GET_CODE (PATTERN (stop_insn
)) == SEQUENCE
)
996 stop_insn
= next_insn (PREV_INSN (stop_insn
));
998 for (insn
= start_insn
; insn
!= stop_insn
;
999 insn
= next_insn_no_annul (insn
))
1002 rtx_insn
*real_insn
= insn
;
1003 enum rtx_code code
= GET_CODE (insn
);
1005 if (DEBUG_INSN_P (insn
))
1008 /* If this insn is from the target of a branch, it isn't going to
1009 be used in the sequel. If it is used in both cases, this
1010 test will not be true. */
1011 if ((code
== INSN
|| code
== JUMP_INSN
|| code
== CALL_INSN
)
1012 && INSN_FROM_TARGET_P (insn
))
1015 /* If this insn is a USE made by update_block, we care about the
1018 && GET_CODE (PATTERN (insn
)) == USE
1019 && INSN_P (XEXP (PATTERN (insn
), 0)))
1020 real_insn
= as_a
<rtx_insn
*> (XEXP (PATTERN (insn
), 0));
1022 if (CALL_P (real_insn
))
1024 /* Values in call-clobbered registers survive a COND_EXEC CALL
1025 if that is not executed; this matters for resoure use because
1026 they may be used by a complementarily (or more strictly)
1027 predicated instruction, or if the CALL is NORETURN. */
1028 if (GET_CODE (PATTERN (real_insn
)) != COND_EXEC
)
1030 HARD_REG_SET regs_invalidated_by_this_call
;
1031 get_call_reg_set_usage (real_insn
,
1032 ®s_invalidated_by_this_call
,
1033 regs_invalidated_by_call
);
1034 /* CALL clobbers all call-used regs that aren't fixed except
1035 sp, ap, and fp. Do this before setting the result of the
1037 AND_COMPL_HARD_REG_SET (current_live_regs
,
1038 regs_invalidated_by_this_call
);
1041 /* A CALL_INSN sets any global register live, since it may
1042 have been modified by the call. */
1043 for (i
= 0; i
< FIRST_PSEUDO_REGISTER
; i
++)
1045 SET_HARD_REG_BIT (current_live_regs
, i
);
1048 /* Mark anything killed in an insn to be deadened at the next
1049 label. Ignore USE insns; the only REG_DEAD notes will be for
1050 parameters. But they might be early. A CALL_INSN will usually
1051 clobber registers used for parameters. It isn't worth bothering
1052 with the unlikely case when it won't. */
1053 if ((NONJUMP_INSN_P (real_insn
)
1054 && GET_CODE (PATTERN (real_insn
)) != USE
1055 && GET_CODE (PATTERN (real_insn
)) != CLOBBER
)
1056 || JUMP_P (real_insn
)
1057 || CALL_P (real_insn
))
1059 for (link
= REG_NOTES (real_insn
); link
; link
= XEXP (link
, 1))
1060 if (REG_NOTE_KIND (link
) == REG_DEAD
1061 && REG_P (XEXP (link
, 0))
1062 && REGNO (XEXP (link
, 0)) < FIRST_PSEUDO_REGISTER
)
1063 add_to_hard_reg_set (&pending_dead_regs
,
1064 GET_MODE (XEXP (link
, 0)),
1065 REGNO (XEXP (link
, 0)));
1067 note_stores (PATTERN (real_insn
), update_live_status
, NULL
);
1069 /* If any registers were unused after this insn, kill them.
1070 These notes will always be accurate. */
1071 for (link
= REG_NOTES (real_insn
); link
; link
= XEXP (link
, 1))
1072 if (REG_NOTE_KIND (link
) == REG_UNUSED
1073 && REG_P (XEXP (link
, 0))
1074 && REGNO (XEXP (link
, 0)) < FIRST_PSEUDO_REGISTER
)
1075 remove_from_hard_reg_set (¤t_live_regs
,
1076 GET_MODE (XEXP (link
, 0)),
1077 REGNO (XEXP (link
, 0)));
1080 else if (LABEL_P (real_insn
))
1084 /* A label clobbers the pending dead registers since neither
1085 reload nor jump will propagate a value across a label. */
1086 AND_COMPL_HARD_REG_SET (current_live_regs
, pending_dead_regs
);
1087 CLEAR_HARD_REG_SET (pending_dead_regs
);
1089 /* We must conservatively assume that all registers that used
1090 to be live here still are. The fallthrough edge may have
1091 left a live register uninitialized. */
1092 bb
= BLOCK_FOR_INSN (real_insn
);
1095 HARD_REG_SET extra_live
;
1097 REG_SET_TO_HARD_REG_SET (extra_live
, DF_LR_IN (bb
));
1098 IOR_HARD_REG_SET (current_live_regs
, extra_live
);
1102 /* The beginning of the epilogue corresponds to the end of the
1103 RTL chain when there are no epilogue insns. Certain resources
1104 are implicitly required at that point. */
1105 else if (NOTE_P (real_insn
)
1106 && NOTE_KIND (real_insn
) == NOTE_INSN_EPILOGUE_BEG
)
1107 IOR_HARD_REG_SET (current_live_regs
, start_of_epilogue_needs
.regs
);
1110 COPY_HARD_REG_SET (res
->regs
, current_live_regs
);
1114 tinfo
->bb_tick
= bb_ticks
[b
];
1118 /* We didn't find the start of a basic block. Assume everything
1119 in use. This should happen only extremely rarely. */
1120 SET_HARD_REG_SET (res
->regs
);
1122 CLEAR_RESOURCE (&set
);
1123 CLEAR_RESOURCE (&needed
);
1125 jump_insn
= find_dead_or_set_registers (target
, res
, &jump_target
, 0,
1128 /* If we hit an unconditional branch, we have another way of finding out
1129 what is live: we can see what is live at the branch target and include
1130 anything used but not set before the branch. We add the live
1131 resources found using the test below to those found until now. */
1135 struct resources new_resources
;
1136 rtx_insn
*stop_insn
= next_active_insn (jump_insn
);
1138 if (!ANY_RETURN_P (jump_target
))
1139 jump_target
= next_active_insn (jump_target
);
1140 mark_target_live_regs (insns
, jump_target
, &new_resources
);
1141 CLEAR_RESOURCE (&set
);
1142 CLEAR_RESOURCE (&needed
);
1144 /* Include JUMP_INSN in the needed registers. */
1145 for (insn
= target
; insn
!= stop_insn
; insn
= next_active_insn (insn
))
1147 mark_referenced_resources (insn
, &needed
, true);
1149 COPY_HARD_REG_SET (scratch
, needed
.regs
);
1150 AND_COMPL_HARD_REG_SET (scratch
, set
.regs
);
1151 IOR_HARD_REG_SET (new_resources
.regs
, scratch
);
1153 mark_set_resources (insn
, &set
, 0, MARK_SRC_DEST_CALL
);
1156 IOR_HARD_REG_SET (res
->regs
, new_resources
.regs
);
1161 COPY_HARD_REG_SET (tinfo
->live_regs
, res
->regs
);
1165 /* Initialize the resources required by mark_target_live_regs ().
1166 This should be invoked before the first call to mark_target_live_regs. */
1169 init_resource_info (rtx_insn
*epilogue_insn
)
1174 /* Indicate what resources are required to be valid at the end of the current
1175 function. The condition code never is and memory always is.
1176 The stack pointer is needed unless EXIT_IGNORE_STACK is true
1177 and there is an epilogue that restores the original stack pointer
1178 from the frame pointer. Registers used to return the function value
1179 are needed. Registers holding global variables are needed. */
1181 end_of_function_needs
.cc
= 0;
1182 end_of_function_needs
.memory
= 1;
1183 CLEAR_HARD_REG_SET (end_of_function_needs
.regs
);
1185 if (frame_pointer_needed
)
1187 SET_HARD_REG_BIT (end_of_function_needs
.regs
, FRAME_POINTER_REGNUM
);
1188 if (!HARD_FRAME_POINTER_IS_FRAME_POINTER
)
1189 SET_HARD_REG_BIT (end_of_function_needs
.regs
,
1190 HARD_FRAME_POINTER_REGNUM
);
1192 if (!(frame_pointer_needed
1193 && EXIT_IGNORE_STACK
1195 && !crtl
->sp_is_unchanging
))
1196 SET_HARD_REG_BIT (end_of_function_needs
.regs
, STACK_POINTER_REGNUM
);
1198 if (crtl
->return_rtx
!= 0)
1199 mark_referenced_resources (crtl
->return_rtx
,
1200 &end_of_function_needs
, true);
1202 for (i
= 0; i
< FIRST_PSEUDO_REGISTER
; i
++)
1203 if (global_regs
[i
] || EPILOGUE_USES (i
))
1204 SET_HARD_REG_BIT (end_of_function_needs
.regs
, i
);
1206 /* The registers required to be live at the end of the function are
1207 represented in the flow information as being dead just prior to
1208 reaching the end of the function. For example, the return of a value
1209 might be represented by a USE of the return register immediately
1210 followed by an unconditional jump to the return label where the
1211 return label is the end of the RTL chain. The end of the RTL chain
1212 is then taken to mean that the return register is live.
1214 This sequence is no longer maintained when epilogue instructions are
1215 added to the RTL chain. To reconstruct the original meaning, the
1216 start of the epilogue (NOTE_INSN_EPILOGUE_BEG) is regarded as the
1217 point where these registers become live (start_of_epilogue_needs).
1218 If epilogue instructions are present, the registers set by those
1219 instructions won't have been processed by flow. Thus, those
1220 registers are additionally required at the end of the RTL chain
1221 (end_of_function_needs). */
1223 start_of_epilogue_needs
= end_of_function_needs
;
1225 while ((epilogue_insn
= next_nonnote_insn (epilogue_insn
)))
1227 mark_set_resources (epilogue_insn
, &end_of_function_needs
, 0,
1228 MARK_SRC_DEST_CALL
);
1229 if (return_insn_p (epilogue_insn
))
1233 /* Allocate and initialize the tables used by mark_target_live_regs. */
1234 target_hash_table
= XCNEWVEC (struct target_info
*, TARGET_HASH_PRIME
);
1235 bb_ticks
= XCNEWVEC (int, last_basic_block_for_fn (cfun
));
1237 /* Set the BLOCK_FOR_INSN of each label that starts a basic block. */
1238 FOR_EACH_BB_FN (bb
, cfun
)
1239 if (LABEL_P (BB_HEAD (bb
)))
1240 BLOCK_FOR_INSN (BB_HEAD (bb
)) = bb
;
1243 /* Free up the resources allocated to mark_target_live_regs (). This
1244 should be invoked after the last call to mark_target_live_regs (). */
1247 free_resource_info (void)
1251 if (target_hash_table
!= NULL
)
1255 for (i
= 0; i
< TARGET_HASH_PRIME
; ++i
)
1257 struct target_info
*ti
= target_hash_table
[i
];
1261 struct target_info
*next
= ti
->next
;
1267 free (target_hash_table
);
1268 target_hash_table
= NULL
;
1271 if (bb_ticks
!= NULL
)
1277 FOR_EACH_BB_FN (bb
, cfun
)
1278 if (LABEL_P (BB_HEAD (bb
)))
1279 BLOCK_FOR_INSN (BB_HEAD (bb
)) = NULL
;
1282 /* Clear any hashed information that we have stored for INSN. */
1285 clear_hashed_info_for_insn (rtx_insn
*insn
)
1287 struct target_info
*tinfo
;
1289 if (target_hash_table
!= NULL
)
1291 for (tinfo
= target_hash_table
[INSN_UID (insn
) % TARGET_HASH_PRIME
];
1292 tinfo
; tinfo
= tinfo
->next
)
1293 if (tinfo
->uid
== INSN_UID (insn
))
1301 /* Increment the tick count for the basic block that contains INSN. */
1304 incr_ticks_for_insn (rtx_insn
*insn
)
1306 int b
= find_basic_block (insn
, MAX_DELAY_SLOT_LIVE_SEARCH
);
1312 /* Add TRIAL to the set of resources used at the end of the current
1315 mark_end_of_function_resources (rtx trial
, bool include_delayed_effects
)
1317 mark_referenced_resources (trial
, &end_of_function_needs
,
1318 include_delayed_effects
);