1 /* Definitions for computing resource usage of specific insns.
2 Copyright (C) 1999, 2000, 2001, 2002, 2003, 2004, 2005
3 Free Software Foundation, Inc.
5 This file is part of GCC.
7 GCC is free software; you can redistribute it and/or modify it under
8 the terms of the GNU General Public License as published by the Free
9 Software Foundation; either version 2, or (at your option) any later
12 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
13 WARRANTY; without even the implied warranty of MERCHANTABILITY or
14 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
17 You should have received a copy of the GNU General Public License
18 along with GCC; see the file COPYING. If not, write to the Free
19 Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA
24 #include "coretypes.h"
29 #include "hard-reg-set.h"
36 #include "insn-attr.h"
39 /* This structure is used to record liveness information at the targets or
40 fallthrough insns of branches. We will most likely need the information
41 at targets again, so save them in a hash table rather than recomputing them
46 int uid
; /* INSN_UID of target. */
47 struct target_info
*next
; /* Next info for same hash bucket. */
48 HARD_REG_SET live_regs
; /* Registers live at target. */
49 int block
; /* Basic block number containing target. */
50 int bb_tick
; /* Generation count of basic block info. */
53 #define TARGET_HASH_PRIME 257
55 /* Indicates what resources are required at the beginning of the epilogue. */
56 static struct resources start_of_epilogue_needs
;
58 /* Indicates what resources are required at function end. */
59 static struct resources end_of_function_needs
;
61 /* Define the hash table itself. */
62 static struct target_info
**target_hash_table
= NULL
;
64 /* For each basic block, we maintain a generation number of its basic
65 block info, which is updated each time we move an insn from the
66 target of a jump. This is the generation number indexed by block
71 /* Marks registers possibly live at the current place being scanned by
72 mark_target_live_regs. Also used by update_live_status. */
74 static HARD_REG_SET current_live_regs
;
76 /* Marks registers for which we have seen a REG_DEAD note but no assignment.
77 Also only used by the next two functions. */
79 static HARD_REG_SET pending_dead_regs
;
81 static void update_live_status (rtx
, rtx
, void *);
82 static int find_basic_block (rtx
, int);
83 static rtx
next_insn_no_annul (rtx
);
84 static rtx
find_dead_or_set_registers (rtx
, struct resources
*,
85 rtx
*, int, struct resources
,
88 /* Utility function called from mark_target_live_regs via note_stores.
89 It deadens any CLOBBERed registers and livens any SET registers. */
92 update_live_status (rtx dest
, rtx x
, void *data ATTRIBUTE_UNUSED
)
94 int first_regno
, last_regno
;
98 && (GET_CODE (dest
) != SUBREG
|| !REG_P (SUBREG_REG (dest
))))
101 if (GET_CODE (dest
) == SUBREG
)
103 first_regno
= subreg_regno (dest
);
104 last_regno
= first_regno
+ subreg_nregs (dest
);
109 first_regno
= REGNO (dest
);
110 last_regno
= END_HARD_REGNO (dest
);
113 if (GET_CODE (x
) == CLOBBER
)
114 for (i
= first_regno
; i
< last_regno
; i
++)
115 CLEAR_HARD_REG_BIT (current_live_regs
, i
);
117 for (i
= first_regno
; i
< last_regno
; i
++)
119 SET_HARD_REG_BIT (current_live_regs
, i
);
120 CLEAR_HARD_REG_BIT (pending_dead_regs
, i
);
124 /* Find the number of the basic block with correct live register
125 information that starts closest to INSN. Return -1 if we couldn't
126 find such a basic block or the beginning is more than
127 SEARCH_LIMIT instructions before INSN. Use SEARCH_LIMIT = -1 for
130 The delay slot filling code destroys the control-flow graph so,
131 instead of finding the basic block containing INSN, we search
132 backwards toward a BARRIER where the live register information is
136 find_basic_block (rtx insn
, int search_limit
)
140 /* Scan backwards to the previous BARRIER. Then see if we can find a
141 label that starts a basic block. Return the basic block number. */
142 for (insn
= prev_nonnote_insn (insn
);
143 insn
&& !BARRIER_P (insn
) && search_limit
!= 0;
144 insn
= prev_nonnote_insn (insn
), --search_limit
)
147 /* The closest BARRIER is too far away. */
148 if (search_limit
== 0)
151 /* The start of the function. */
153 return ENTRY_BLOCK_PTR
->next_bb
->index
;
155 /* See if any of the upcoming CODE_LABELs start a basic block. If we reach
156 anything other than a CODE_LABEL or note, we can't find this code. */
157 for (insn
= next_nonnote_insn (insn
);
158 insn
&& LABEL_P (insn
);
159 insn
= next_nonnote_insn (insn
))
162 if (insn
== BB_HEAD (bb
))
169 /* Similar to next_insn, but ignores insns in the delay slots of
170 an annulled branch. */
173 next_insn_no_annul (rtx insn
)
177 /* If INSN is an annulled branch, skip any insns from the target
180 && INSN_ANNULLED_BRANCH_P (insn
)
181 && NEXT_INSN (PREV_INSN (insn
)) != insn
)
183 rtx next
= NEXT_INSN (insn
);
184 enum rtx_code code
= GET_CODE (next
);
186 while ((code
== INSN
|| code
== JUMP_INSN
|| code
== CALL_INSN
)
187 && INSN_FROM_TARGET_P (next
))
190 next
= NEXT_INSN (insn
);
191 code
= GET_CODE (next
);
195 insn
= NEXT_INSN (insn
);
196 if (insn
&& NONJUMP_INSN_P (insn
)
197 && GET_CODE (PATTERN (insn
)) == SEQUENCE
)
198 insn
= XVECEXP (PATTERN (insn
), 0, 0);
204 /* Given X, some rtl, and RES, a pointer to a `struct resource', mark
205 which resources are referenced by the insn. If INCLUDE_DELAYED_EFFECTS
206 is TRUE, resources used by the called routine will be included for
210 mark_referenced_resources (rtx x
, struct resources
*res
,
211 int include_delayed_effects
)
213 enum rtx_code code
= GET_CODE (x
);
216 const char *format_ptr
;
218 /* Handle leaf items for which we set resource flags. Also, special-case
219 CALL, SET and CLOBBER operators. */
232 if (!REG_P (SUBREG_REG (x
)))
233 mark_referenced_resources (SUBREG_REG (x
), res
, 0);
236 unsigned int regno
= subreg_regno (x
);
237 unsigned int last_regno
= regno
+ subreg_nregs (x
);
239 gcc_assert (last_regno
<= FIRST_PSEUDO_REGISTER
);
240 for (r
= regno
; r
< last_regno
; r
++)
241 SET_HARD_REG_BIT (res
->regs
, r
);
246 gcc_assert (HARD_REGISTER_P (x
));
247 add_to_hard_reg_set (&res
->regs
, GET_MODE (x
), REGNO (x
));
251 /* If this memory shouldn't change, it really isn't referencing
253 if (MEM_READONLY_P (x
))
254 res
->unch_memory
= 1;
257 res
->volatil
|= MEM_VOLATILE_P (x
);
259 /* Mark registers used to access memory. */
260 mark_referenced_resources (XEXP (x
, 0), res
, 0);
267 case UNSPEC_VOLATILE
:
269 /* Traditional asm's are always volatile. */
278 res
->volatil
|= MEM_VOLATILE_P (x
);
280 /* For all ASM_OPERANDS, we must traverse the vector of input operands.
281 We can not just fall through here since then we would be confused
282 by the ASM_INPUT rtx inside ASM_OPERANDS, which do not indicate
283 traditional asms unlike their normal usage. */
285 for (i
= 0; i
< ASM_OPERANDS_INPUT_LENGTH (x
); i
++)
286 mark_referenced_resources (ASM_OPERANDS_INPUT (x
, i
), res
, 0);
290 /* The first operand will be a (MEM (xxx)) but doesn't really reference
291 memory. The second operand may be referenced, though. */
292 mark_referenced_resources (XEXP (XEXP (x
, 0), 0), res
, 0);
293 mark_referenced_resources (XEXP (x
, 1), res
, 0);
297 /* Usually, the first operand of SET is set, not referenced. But
298 registers used to access memory are referenced. SET_DEST is
299 also referenced if it is a ZERO_EXTRACT. */
301 mark_referenced_resources (SET_SRC (x
), res
, 0);
304 if (GET_CODE (x
) == ZERO_EXTRACT
305 || GET_CODE (x
) == STRICT_LOW_PART
)
306 mark_referenced_resources (x
, res
, 0);
307 else if (GET_CODE (x
) == SUBREG
)
310 mark_referenced_resources (XEXP (x
, 0), res
, 0);
317 if (include_delayed_effects
)
319 /* A CALL references memory, the frame pointer if it exists, the
320 stack pointer, any global registers and any registers given in
321 USE insns immediately in front of the CALL.
323 However, we may have moved some of the parameter loading insns
324 into the delay slot of this CALL. If so, the USE's for them
325 don't count and should be skipped. */
326 rtx insn
= PREV_INSN (x
);
331 /* If we are part of a delay slot sequence, point at the SEQUENCE. */
332 if (NEXT_INSN (insn
) != x
)
334 sequence
= PATTERN (NEXT_INSN (insn
));
335 seq_size
= XVECLEN (sequence
, 0);
336 gcc_assert (GET_CODE (sequence
) == SEQUENCE
);
340 SET_HARD_REG_BIT (res
->regs
, STACK_POINTER_REGNUM
);
341 if (frame_pointer_needed
)
343 SET_HARD_REG_BIT (res
->regs
, FRAME_POINTER_REGNUM
);
344 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
345 SET_HARD_REG_BIT (res
->regs
, HARD_FRAME_POINTER_REGNUM
);
349 for (i
= 0; i
< FIRST_PSEUDO_REGISTER
; i
++)
351 SET_HARD_REG_BIT (res
->regs
, i
);
353 /* Check for a REG_SETJMP. If it exists, then we must
354 assume that this call can need any register.
356 This is done to be more conservative about how we handle setjmp.
357 We assume that they both use and set all registers. Using all
358 registers ensures that a register will not be considered dead
359 just because it crosses a setjmp call. A register should be
360 considered dead only if the setjmp call returns nonzero. */
361 if (find_reg_note (x
, REG_SETJMP
, NULL
))
362 SET_HARD_REG_SET (res
->regs
);
367 for (link
= CALL_INSN_FUNCTION_USAGE (x
);
369 link
= XEXP (link
, 1))
370 if (GET_CODE (XEXP (link
, 0)) == USE
)
372 for (i
= 1; i
< seq_size
; i
++)
374 rtx slot_pat
= PATTERN (XVECEXP (sequence
, 0, i
));
375 if (GET_CODE (slot_pat
) == SET
376 && rtx_equal_p (SET_DEST (slot_pat
),
377 XEXP (XEXP (link
, 0), 0)))
381 mark_referenced_resources (XEXP (XEXP (link
, 0), 0),
387 /* ... fall through to other INSN processing ... */
392 #ifdef INSN_REFERENCES_ARE_DELAYED
393 if (! include_delayed_effects
394 && INSN_REFERENCES_ARE_DELAYED (x
))
398 /* No special processing, just speed up. */
399 mark_referenced_resources (PATTERN (x
), res
, include_delayed_effects
);
406 /* Process each sub-expression and flag what it needs. */
407 format_ptr
= GET_RTX_FORMAT (code
);
408 for (i
= 0; i
< GET_RTX_LENGTH (code
); i
++)
409 switch (*format_ptr
++)
412 mark_referenced_resources (XEXP (x
, i
), res
, include_delayed_effects
);
416 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
417 mark_referenced_resources (XVECEXP (x
, i
, j
), res
,
418 include_delayed_effects
);
423 /* A subroutine of mark_target_live_regs. Search forward from TARGET
424 looking for registers that are set before they are used. These are dead.
425 Stop after passing a few conditional jumps, and/or a small
426 number of unconditional branches. */
429 find_dead_or_set_registers (rtx target
, struct resources
*res
,
430 rtx
*jump_target
, int jump_count
,
431 struct resources set
, struct resources needed
)
433 HARD_REG_SET scratch
;
438 for (insn
= target
; insn
; insn
= next
)
440 rtx this_jump_insn
= insn
;
442 next
= NEXT_INSN (insn
);
444 /* If this instruction can throw an exception, then we don't
445 know where we might end up next. That means that we have to
446 assume that whatever we have already marked as live really is
448 if (can_throw_internal (insn
))
451 switch (GET_CODE (insn
))
454 /* After a label, any pending dead registers that weren't yet
455 used can be made dead. */
456 AND_COMPL_HARD_REG_SET (pending_dead_regs
, needed
.regs
);
457 AND_COMPL_HARD_REG_SET (res
->regs
, pending_dead_regs
);
458 CLEAR_HARD_REG_SET (pending_dead_regs
);
467 if (GET_CODE (PATTERN (insn
)) == USE
)
469 /* If INSN is a USE made by update_block, we care about the
470 underlying insn. Any registers set by the underlying insn
471 are live since the insn is being done somewhere else. */
472 if (INSN_P (XEXP (PATTERN (insn
), 0)))
473 mark_set_resources (XEXP (PATTERN (insn
), 0), res
, 0,
476 /* All other USE insns are to be ignored. */
479 else if (GET_CODE (PATTERN (insn
)) == CLOBBER
)
481 else if (GET_CODE (PATTERN (insn
)) == SEQUENCE
)
483 /* An unconditional jump can be used to fill the delay slot
484 of a call, so search for a JUMP_INSN in any position. */
485 for (i
= 0; i
< XVECLEN (PATTERN (insn
), 0); i
++)
487 this_jump_insn
= XVECEXP (PATTERN (insn
), 0, i
);
488 if (JUMP_P (this_jump_insn
))
497 if (JUMP_P (this_jump_insn
))
499 if (jump_count
++ < 10)
501 if (any_uncondjump_p (this_jump_insn
)
502 || GET_CODE (PATTERN (this_jump_insn
)) == RETURN
)
504 next
= JUMP_LABEL (this_jump_insn
);
509 *jump_target
= JUMP_LABEL (this_jump_insn
);
512 else if (any_condjump_p (this_jump_insn
))
514 struct resources target_set
, target_res
;
515 struct resources fallthrough_res
;
517 /* We can handle conditional branches here by following
518 both paths, and then IOR the results of the two paths
519 together, which will give us registers that are dead
520 on both paths. Since this is expensive, we give it
521 a much higher cost than unconditional branches. The
522 cost was chosen so that we will follow at most 1
523 conditional branch. */
526 if (jump_count
>= 10)
529 mark_referenced_resources (insn
, &needed
, 1);
531 /* For an annulled branch, mark_set_resources ignores slots
532 filled by instructions from the target. This is correct
533 if the branch is not taken. Since we are following both
534 paths from the branch, we must also compute correct info
535 if the branch is taken. We do this by inverting all of
536 the INSN_FROM_TARGET_P bits, calling mark_set_resources,
537 and then inverting the INSN_FROM_TARGET_P bits again. */
539 if (GET_CODE (PATTERN (insn
)) == SEQUENCE
540 && INSN_ANNULLED_BRANCH_P (this_jump_insn
))
542 for (i
= 1; i
< XVECLEN (PATTERN (insn
), 0); i
++)
543 INSN_FROM_TARGET_P (XVECEXP (PATTERN (insn
), 0, i
))
544 = ! INSN_FROM_TARGET_P (XVECEXP (PATTERN (insn
), 0, i
));
547 mark_set_resources (insn
, &target_set
, 0,
550 for (i
= 1; i
< XVECLEN (PATTERN (insn
), 0); i
++)
551 INSN_FROM_TARGET_P (XVECEXP (PATTERN (insn
), 0, i
))
552 = ! INSN_FROM_TARGET_P (XVECEXP (PATTERN (insn
), 0, i
));
554 mark_set_resources (insn
, &set
, 0, MARK_SRC_DEST_CALL
);
558 mark_set_resources (insn
, &set
, 0, MARK_SRC_DEST_CALL
);
563 COPY_HARD_REG_SET (scratch
, target_set
.regs
);
564 AND_COMPL_HARD_REG_SET (scratch
, needed
.regs
);
565 AND_COMPL_HARD_REG_SET (target_res
.regs
, scratch
);
567 fallthrough_res
= *res
;
568 COPY_HARD_REG_SET (scratch
, set
.regs
);
569 AND_COMPL_HARD_REG_SET (scratch
, needed
.regs
);
570 AND_COMPL_HARD_REG_SET (fallthrough_res
.regs
, scratch
);
572 find_dead_or_set_registers (JUMP_LABEL (this_jump_insn
),
573 &target_res
, 0, jump_count
,
575 find_dead_or_set_registers (next
,
576 &fallthrough_res
, 0, jump_count
,
578 IOR_HARD_REG_SET (fallthrough_res
.regs
, target_res
.regs
);
579 AND_HARD_REG_SET (res
->regs
, fallthrough_res
.regs
);
587 /* Don't try this optimization if we expired our jump count
588 above, since that would mean there may be an infinite loop
589 in the function being compiled. */
595 mark_referenced_resources (insn
, &needed
, 1);
596 mark_set_resources (insn
, &set
, 0, MARK_SRC_DEST_CALL
);
598 COPY_HARD_REG_SET (scratch
, set
.regs
);
599 AND_COMPL_HARD_REG_SET (scratch
, needed
.regs
);
600 AND_COMPL_HARD_REG_SET (res
->regs
, scratch
);
606 /* Given X, a part of an insn, and a pointer to a `struct resource',
607 RES, indicate which resources are modified by the insn. If
608 MARK_TYPE is MARK_SRC_DEST_CALL, also mark resources potentially
609 set by the called routine.
611 If IN_DEST is nonzero, it means we are inside a SET. Otherwise,
612 objects are being referenced instead of set.
614 We never mark the insn as modifying the condition code unless it explicitly
615 SETs CC0 even though this is not totally correct. The reason for this is
616 that we require a SET of CC0 to immediately precede the reference to CC0.
617 So if some other insn sets CC0 as a side-effect, we know it cannot affect
618 our computation and thus may be placed in a delay slot. */
621 mark_set_resources (rtx x
, struct resources
*res
, int in_dest
,
622 enum mark_resource_type mark_type
)
627 const char *format_ptr
;
646 /* These don't set any resources. */
655 /* Called routine modifies the condition code, memory, any registers
656 that aren't saved across calls, global registers and anything
657 explicitly CLOBBERed immediately after the CALL_INSN. */
659 if (mark_type
== MARK_SRC_DEST_CALL
)
663 res
->cc
= res
->memory
= 1;
664 for (r
= 0; r
< FIRST_PSEUDO_REGISTER
; r
++)
665 if (call_used_regs
[r
] || global_regs
[r
])
666 SET_HARD_REG_BIT (res
->regs
, r
);
668 for (link
= CALL_INSN_FUNCTION_USAGE (x
);
669 link
; link
= XEXP (link
, 1))
670 if (GET_CODE (XEXP (link
, 0)) == CLOBBER
)
671 mark_set_resources (SET_DEST (XEXP (link
, 0)), res
, 1,
674 /* Check for a REG_SETJMP. If it exists, then we must
675 assume that this call can clobber any register. */
676 if (find_reg_note (x
, REG_SETJMP
, NULL
))
677 SET_HARD_REG_SET (res
->regs
);
680 /* ... and also what its RTL says it modifies, if anything. */
685 /* An insn consisting of just a CLOBBER (or USE) is just for flow
686 and doesn't actually do anything, so we ignore it. */
688 #ifdef INSN_SETS_ARE_DELAYED
689 if (mark_type
!= MARK_SRC_DEST_CALL
690 && INSN_SETS_ARE_DELAYED (x
))
695 if (GET_CODE (x
) != USE
&& GET_CODE (x
) != CLOBBER
)
700 /* If the source of a SET is a CALL, this is actually done by
701 the called routine. So only include it if we are to include the
702 effects of the calling routine. */
704 mark_set_resources (SET_DEST (x
), res
,
705 (mark_type
== MARK_SRC_DEST_CALL
706 || GET_CODE (SET_SRC (x
)) != CALL
),
709 mark_set_resources (SET_SRC (x
), res
, 0, MARK_SRC_DEST
);
713 mark_set_resources (XEXP (x
, 0), res
, 1, MARK_SRC_DEST
);
717 for (i
= 0; i
< XVECLEN (x
, 0); i
++)
718 if (! (INSN_ANNULLED_BRANCH_P (XVECEXP (x
, 0, 0))
719 && INSN_FROM_TARGET_P (XVECEXP (x
, 0, i
))))
720 mark_set_resources (XVECEXP (x
, 0, i
), res
, 0, mark_type
);
727 mark_set_resources (XEXP (x
, 0), res
, 1, MARK_SRC_DEST
);
732 mark_set_resources (XEXP (x
, 0), res
, 1, MARK_SRC_DEST
);
733 mark_set_resources (XEXP (XEXP (x
, 1), 0), res
, 0, MARK_SRC_DEST
);
734 mark_set_resources (XEXP (XEXP (x
, 1), 1), res
, 0, MARK_SRC_DEST
);
739 mark_set_resources (XEXP (x
, 0), res
, in_dest
, MARK_SRC_DEST
);
740 mark_set_resources (XEXP (x
, 1), res
, 0, MARK_SRC_DEST
);
741 mark_set_resources (XEXP (x
, 2), res
, 0, MARK_SRC_DEST
);
748 res
->unch_memory
|= MEM_READONLY_P (x
);
749 res
->volatil
|= MEM_VOLATILE_P (x
);
752 mark_set_resources (XEXP (x
, 0), res
, 0, MARK_SRC_DEST
);
758 if (!REG_P (SUBREG_REG (x
)))
759 mark_set_resources (SUBREG_REG (x
), res
, in_dest
, mark_type
);
762 unsigned int regno
= subreg_regno (x
);
763 unsigned int last_regno
= regno
+ subreg_nregs (x
);
765 gcc_assert (last_regno
<= FIRST_PSEUDO_REGISTER
);
766 for (r
= regno
; r
< last_regno
; r
++)
767 SET_HARD_REG_BIT (res
->regs
, r
);
775 gcc_assert (HARD_REGISTER_P (x
));
776 add_to_hard_reg_set (&res
->regs
, GET_MODE (x
), REGNO (x
));
780 case UNSPEC_VOLATILE
:
782 /* Traditional asm's are always volatile. */
791 res
->volatil
|= MEM_VOLATILE_P (x
);
793 /* For all ASM_OPERANDS, we must traverse the vector of input operands.
794 We can not just fall through here since then we would be confused
795 by the ASM_INPUT rtx inside ASM_OPERANDS, which do not indicate
796 traditional asms unlike their normal usage. */
798 for (i
= 0; i
< ASM_OPERANDS_INPUT_LENGTH (x
); i
++)
799 mark_set_resources (ASM_OPERANDS_INPUT (x
, i
), res
, in_dest
,
807 /* Process each sub-expression and flag what it needs. */
808 format_ptr
= GET_RTX_FORMAT (code
);
809 for (i
= 0; i
< GET_RTX_LENGTH (code
); i
++)
810 switch (*format_ptr
++)
813 mark_set_resources (XEXP (x
, i
), res
, in_dest
, mark_type
);
817 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
818 mark_set_resources (XVECEXP (x
, i
, j
), res
, in_dest
, mark_type
);
823 /* Return TRUE if INSN is a return, possibly with a filled delay slot. */
826 return_insn_p (rtx insn
)
828 if (JUMP_P (insn
) && GET_CODE (PATTERN (insn
)) == RETURN
)
831 if (NONJUMP_INSN_P (insn
) && GET_CODE (PATTERN (insn
)) == SEQUENCE
)
832 return return_insn_p (XVECEXP (PATTERN (insn
), 0, 0));
837 /* Set the resources that are live at TARGET.
839 If TARGET is zero, we refer to the end of the current function and can
840 return our precomputed value.
842 Otherwise, we try to find out what is live by consulting the basic block
843 information. This is tricky, because we must consider the actions of
844 reload and jump optimization, which occur after the basic block information
847 Accordingly, we proceed as follows::
849 We find the previous BARRIER and look at all immediately following labels
850 (with no intervening active insns) to see if any of them start a basic
851 block. If we hit the start of the function first, we use block 0.
853 Once we have found a basic block and a corresponding first insns, we can
854 accurately compute the live status from basic_block_live_regs and
855 reg_renumber. (By starting at a label following a BARRIER, we are immune
856 to actions taken by reload and jump.) Then we scan all insns between
857 that point and our target. For each CLOBBER (or for call-clobbered regs
858 when we pass a CALL_INSN), mark the appropriate registers are dead. For
859 a SET, mark them as live.
861 We have to be careful when using REG_DEAD notes because they are not
862 updated by such things as find_equiv_reg. So keep track of registers
863 marked as dead that haven't been assigned to, and mark them dead at the
864 next CODE_LABEL since reload and jump won't propagate values across labels.
866 If we cannot find the start of a basic block (should be a very rare
867 case, if it can happen at all), mark everything as potentially live.
869 Next, scan forward from TARGET looking for things set or clobbered
870 before they are used. These are not live.
872 Because we can be called many times on the same target, save our results
873 in a hash table indexed by INSN_UID. This is only done if the function
874 init_resource_info () was invoked before we are called. */
877 mark_target_live_regs (rtx insns
, rtx target
, struct resources
*res
)
881 struct target_info
*tinfo
= NULL
;
885 HARD_REG_SET scratch
;
886 struct resources set
, needed
;
888 /* Handle end of function. */
891 *res
= end_of_function_needs
;
895 /* Handle return insn. */
896 else if (return_insn_p (target
))
898 *res
= end_of_function_needs
;
899 mark_referenced_resources (target
, res
, 0);
903 /* We have to assume memory is needed, but the CC isn't. */
905 res
->volatil
= res
->unch_memory
= 0;
908 /* See if we have computed this value already. */
909 if (target_hash_table
!= NULL
)
911 for (tinfo
= target_hash_table
[INSN_UID (target
) % TARGET_HASH_PRIME
];
912 tinfo
; tinfo
= tinfo
->next
)
913 if (tinfo
->uid
== INSN_UID (target
))
916 /* Start by getting the basic block number. If we have saved
917 information, we can get it from there unless the insn at the
918 start of the basic block has been deleted. */
919 if (tinfo
&& tinfo
->block
!= -1
920 && ! INSN_DELETED_P (BB_HEAD (BASIC_BLOCK (tinfo
->block
))))
925 b
= find_basic_block (target
, MAX_DELAY_SLOT_LIVE_SEARCH
);
927 if (target_hash_table
!= NULL
)
931 /* If the information is up-to-date, use it. Otherwise, we will
933 if (b
== tinfo
->block
&& b
!= -1 && tinfo
->bb_tick
== bb_ticks
[b
])
935 COPY_HARD_REG_SET (res
->regs
, tinfo
->live_regs
);
941 /* Allocate a place to put our results and chain it into the
943 tinfo
= XNEW (struct target_info
);
944 tinfo
->uid
= INSN_UID (target
);
947 = target_hash_table
[INSN_UID (target
) % TARGET_HASH_PRIME
];
948 target_hash_table
[INSN_UID (target
) % TARGET_HASH_PRIME
] = tinfo
;
952 CLEAR_HARD_REG_SET (pending_dead_regs
);
954 /* If we found a basic block, get the live registers from it and update
955 them with anything set or killed between its start and the insn before
956 TARGET. Otherwise, we must assume everything is live. */
959 regset regs_live
= BASIC_BLOCK (b
)->il
.rtl
->global_live_at_start
;
960 rtx start_insn
, stop_insn
;
961 reg_set_iterator rsi
;
963 /* Compute hard regs live at start of block -- this is the real hard regs
964 marked live, plus live pseudo regs that have been renumbered to
967 REG_SET_TO_HARD_REG_SET (current_live_regs
, regs_live
);
969 EXECUTE_IF_SET_IN_REG_SET (regs_live
, FIRST_PSEUDO_REGISTER
, i
, rsi
)
971 if (reg_renumber
[i
] >= 0)
972 add_to_hard_reg_set (¤t_live_regs
, PSEUDO_REGNO_MODE (i
),
976 /* Get starting and ending insn, handling the case where each might
978 start_insn
= (b
== 0 ? insns
: BB_HEAD (BASIC_BLOCK (b
)));
981 if (NONJUMP_INSN_P (start_insn
)
982 && GET_CODE (PATTERN (start_insn
)) == SEQUENCE
)
983 start_insn
= XVECEXP (PATTERN (start_insn
), 0, 0);
985 if (NONJUMP_INSN_P (stop_insn
)
986 && GET_CODE (PATTERN (stop_insn
)) == SEQUENCE
)
987 stop_insn
= next_insn (PREV_INSN (stop_insn
));
989 for (insn
= start_insn
; insn
!= stop_insn
;
990 insn
= next_insn_no_annul (insn
))
993 rtx real_insn
= insn
;
994 enum rtx_code code
= GET_CODE (insn
);
996 /* If this insn is from the target of a branch, it isn't going to
997 be used in the sequel. If it is used in both cases, this
998 test will not be true. */
999 if ((code
== INSN
|| code
== JUMP_INSN
|| code
== CALL_INSN
)
1000 && INSN_FROM_TARGET_P (insn
))
1003 /* If this insn is a USE made by update_block, we care about the
1005 if (code
== INSN
&& GET_CODE (PATTERN (insn
)) == USE
1006 && INSN_P (XEXP (PATTERN (insn
), 0)))
1007 real_insn
= XEXP (PATTERN (insn
), 0);
1009 if (CALL_P (real_insn
))
1011 /* CALL clobbers all call-used regs that aren't fixed except
1012 sp, ap, and fp. Do this before setting the result of the
1014 AND_COMPL_HARD_REG_SET (current_live_regs
,
1015 regs_invalidated_by_call
);
1017 /* A CALL_INSN sets any global register live, since it may
1018 have been modified by the call. */
1019 for (i
= 0; i
< FIRST_PSEUDO_REGISTER
; i
++)
1021 SET_HARD_REG_BIT (current_live_regs
, i
);
1024 /* Mark anything killed in an insn to be deadened at the next
1025 label. Ignore USE insns; the only REG_DEAD notes will be for
1026 parameters. But they might be early. A CALL_INSN will usually
1027 clobber registers used for parameters. It isn't worth bothering
1028 with the unlikely case when it won't. */
1029 if ((NONJUMP_INSN_P (real_insn
)
1030 && GET_CODE (PATTERN (real_insn
)) != USE
1031 && GET_CODE (PATTERN (real_insn
)) != CLOBBER
)
1032 || JUMP_P (real_insn
)
1033 || CALL_P (real_insn
))
1035 for (link
= REG_NOTES (real_insn
); link
; link
= XEXP (link
, 1))
1036 if (REG_NOTE_KIND (link
) == REG_DEAD
1037 && REG_P (XEXP (link
, 0))
1038 && REGNO (XEXP (link
, 0)) < FIRST_PSEUDO_REGISTER
)
1039 add_to_hard_reg_set (&pending_dead_regs
,
1040 GET_MODE (XEXP (link
, 0)),
1041 REGNO (XEXP (link
, 0)));
1043 note_stores (PATTERN (real_insn
), update_live_status
, NULL
);
1045 /* If any registers were unused after this insn, kill them.
1046 These notes will always be accurate. */
1047 for (link
= REG_NOTES (real_insn
); link
; link
= XEXP (link
, 1))
1048 if (REG_NOTE_KIND (link
) == REG_UNUSED
1049 && REG_P (XEXP (link
, 0))
1050 && REGNO (XEXP (link
, 0)) < FIRST_PSEUDO_REGISTER
)
1051 remove_from_hard_reg_set (¤t_live_regs
,
1052 GET_MODE (XEXP (link
, 0)),
1053 REGNO (XEXP (link
, 0)));
1056 else if (LABEL_P (real_insn
))
1058 /* A label clobbers the pending dead registers since neither
1059 reload nor jump will propagate a value across a label. */
1060 AND_COMPL_HARD_REG_SET (current_live_regs
, pending_dead_regs
);
1061 CLEAR_HARD_REG_SET (pending_dead_regs
);
1064 /* The beginning of the epilogue corresponds to the end of the
1065 RTL chain when there are no epilogue insns. Certain resources
1066 are implicitly required at that point. */
1067 else if (NOTE_P (real_insn
)
1068 && NOTE_KIND (real_insn
) == NOTE_INSN_EPILOGUE_BEG
)
1069 IOR_HARD_REG_SET (current_live_regs
, start_of_epilogue_needs
.regs
);
1072 COPY_HARD_REG_SET (res
->regs
, current_live_regs
);
1076 tinfo
->bb_tick
= bb_ticks
[b
];
1080 /* We didn't find the start of a basic block. Assume everything
1081 in use. This should happen only extremely rarely. */
1082 SET_HARD_REG_SET (res
->regs
);
1084 CLEAR_RESOURCE (&set
);
1085 CLEAR_RESOURCE (&needed
);
1087 jump_insn
= find_dead_or_set_registers (target
, res
, &jump_target
, 0,
1090 /* If we hit an unconditional branch, we have another way of finding out
1091 what is live: we can see what is live at the branch target and include
1092 anything used but not set before the branch. We add the live
1093 resources found using the test below to those found until now. */
1097 struct resources new_resources
;
1098 rtx stop_insn
= next_active_insn (jump_insn
);
1100 mark_target_live_regs (insns
, next_active_insn (jump_target
),
1102 CLEAR_RESOURCE (&set
);
1103 CLEAR_RESOURCE (&needed
);
1105 /* Include JUMP_INSN in the needed registers. */
1106 for (insn
= target
; insn
!= stop_insn
; insn
= next_active_insn (insn
))
1108 mark_referenced_resources (insn
, &needed
, 1);
1110 COPY_HARD_REG_SET (scratch
, needed
.regs
);
1111 AND_COMPL_HARD_REG_SET (scratch
, set
.regs
);
1112 IOR_HARD_REG_SET (new_resources
.regs
, scratch
);
1114 mark_set_resources (insn
, &set
, 0, MARK_SRC_DEST_CALL
);
1117 IOR_HARD_REG_SET (res
->regs
, new_resources
.regs
);
1122 COPY_HARD_REG_SET (tinfo
->live_regs
, res
->regs
);
1126 /* Initialize the resources required by mark_target_live_regs ().
1127 This should be invoked before the first call to mark_target_live_regs. */
1130 init_resource_info (rtx epilogue_insn
)
1134 /* Indicate what resources are required to be valid at the end of the current
1135 function. The condition code never is and memory always is. If the
1136 frame pointer is needed, it is and so is the stack pointer unless
1137 EXIT_IGNORE_STACK is nonzero. If the frame pointer is not needed, the
1138 stack pointer is. Registers used to return the function value are
1139 needed. Registers holding global variables are needed. */
1141 end_of_function_needs
.cc
= 0;
1142 end_of_function_needs
.memory
= 1;
1143 end_of_function_needs
.unch_memory
= 0;
1144 CLEAR_HARD_REG_SET (end_of_function_needs
.regs
);
1146 if (frame_pointer_needed
)
1148 SET_HARD_REG_BIT (end_of_function_needs
.regs
, FRAME_POINTER_REGNUM
);
1149 #if HARD_FRAME_POINTER_REGNUM != FRAME_POINTER_REGNUM
1150 SET_HARD_REG_BIT (end_of_function_needs
.regs
, HARD_FRAME_POINTER_REGNUM
);
1152 if (! EXIT_IGNORE_STACK
1153 || current_function_sp_is_unchanging
)
1154 SET_HARD_REG_BIT (end_of_function_needs
.regs
, STACK_POINTER_REGNUM
);
1157 SET_HARD_REG_BIT (end_of_function_needs
.regs
, STACK_POINTER_REGNUM
);
1159 if (current_function_return_rtx
!= 0)
1160 mark_referenced_resources (current_function_return_rtx
,
1161 &end_of_function_needs
, 1);
1163 for (i
= 0; i
< FIRST_PSEUDO_REGISTER
; i
++)
1165 #ifdef EPILOGUE_USES
1166 || EPILOGUE_USES (i
)
1169 SET_HARD_REG_BIT (end_of_function_needs
.regs
, i
);
1171 /* The registers required to be live at the end of the function are
1172 represented in the flow information as being dead just prior to
1173 reaching the end of the function. For example, the return of a value
1174 might be represented by a USE of the return register immediately
1175 followed by an unconditional jump to the return label where the
1176 return label is the end of the RTL chain. The end of the RTL chain
1177 is then taken to mean that the return register is live.
1179 This sequence is no longer maintained when epilogue instructions are
1180 added to the RTL chain. To reconstruct the original meaning, the
1181 start of the epilogue (NOTE_INSN_EPILOGUE_BEG) is regarded as the
1182 point where these registers become live (start_of_epilogue_needs).
1183 If epilogue instructions are present, the registers set by those
1184 instructions won't have been processed by flow. Thus, those
1185 registers are additionally required at the end of the RTL chain
1186 (end_of_function_needs). */
1188 start_of_epilogue_needs
= end_of_function_needs
;
1190 while ((epilogue_insn
= next_nonnote_insn (epilogue_insn
)))
1192 mark_set_resources (epilogue_insn
, &end_of_function_needs
, 0,
1193 MARK_SRC_DEST_CALL
);
1194 if (return_insn_p (epilogue_insn
))
1198 /* Allocate and initialize the tables used by mark_target_live_regs. */
1199 target_hash_table
= XCNEWVEC (struct target_info
*, TARGET_HASH_PRIME
);
1200 bb_ticks
= XCNEWVEC (int, last_basic_block
);
1203 /* Free up the resources allocated to mark_target_live_regs (). This
1204 should be invoked after the last call to mark_target_live_regs (). */
1207 free_resource_info (void)
1209 if (target_hash_table
!= NULL
)
1213 for (i
= 0; i
< TARGET_HASH_PRIME
; ++i
)
1215 struct target_info
*ti
= target_hash_table
[i
];
1219 struct target_info
*next
= ti
->next
;
1225 free (target_hash_table
);
1226 target_hash_table
= NULL
;
1229 if (bb_ticks
!= NULL
)
1236 /* Clear any hashed information that we have stored for INSN. */
1239 clear_hashed_info_for_insn (rtx insn
)
1241 struct target_info
*tinfo
;
1243 if (target_hash_table
!= NULL
)
1245 for (tinfo
= target_hash_table
[INSN_UID (insn
) % TARGET_HASH_PRIME
];
1246 tinfo
; tinfo
= tinfo
->next
)
1247 if (tinfo
->uid
== INSN_UID (insn
))
1255 /* Increment the tick count for the basic block that contains INSN. */
1258 incr_ticks_for_insn (rtx insn
)
1260 int b
= find_basic_block (insn
, MAX_DELAY_SLOT_LIVE_SEARCH
);
1266 /* Add TRIAL to the set of resources used at the end of the current
1269 mark_end_of_function_resources (rtx trial
, int include_delayed_effects
)
1271 mark_referenced_resources (trial
, &end_of_function_needs
,
1272 include_delayed_effects
);