1 /* Definitions for computing resource usage of specific insns.
2 Copyright (C) 1999, 2000, 2001, 2002, 2003
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, 59 Temple Place - Suite 330, Boston, MA
24 #include "coretypes.h"
29 #include "hard-reg-set.h"
30 #include "basic-block.h"
37 #include "insn-attr.h"
40 /* This structure is used to record liveness information at the targets or
41 fallthrough insns of branches. We will most likely need the information
42 at targets again, so save them in a hash table rather than recomputing them
47 int uid
; /* INSN_UID of target. */
48 struct target_info
*next
; /* Next info for same hash bucket. */
49 HARD_REG_SET live_regs
; /* Registers live at target. */
50 int block
; /* Basic block number containing target. */
51 int bb_tick
; /* Generation count of basic block info. */
54 #define TARGET_HASH_PRIME 257
56 /* Indicates what resources are required at the beginning of the epilogue. */
57 static struct resources start_of_epilogue_needs
;
59 /* Indicates what resources are required at function end. */
60 static struct resources end_of_function_needs
;
62 /* Define the hash table itself. */
63 static struct target_info
**target_hash_table
= NULL
;
65 /* For each basic block, we maintain a generation number of its basic
66 block info, which is updated each time we move an insn from the
67 target of a jump. This is the generation number indexed by block
72 /* Marks registers possibly live at the current place being scanned by
73 mark_target_live_regs. Also used by update_live_status. */
75 static HARD_REG_SET current_live_regs
;
77 /* Marks registers for which we have seen a REG_DEAD note but no assignment.
78 Also only used by the next two functions. */
80 static HARD_REG_SET pending_dead_regs
;
82 static void update_live_status (rtx
, rtx
, void *);
83 static int find_basic_block (rtx
, int);
84 static rtx
next_insn_no_annul (rtx
);
85 static rtx
find_dead_or_set_registers (rtx
, struct resources
*,
86 rtx
*, int, struct resources
,
89 /* Utility function called from mark_target_live_regs via note_stores.
90 It deadens any CLOBBERed registers and livens any SET registers. */
93 update_live_status (rtx dest
, rtx x
, void *data ATTRIBUTE_UNUSED
)
95 int first_regno
, last_regno
;
98 if (GET_CODE (dest
) != REG
99 && (GET_CODE (dest
) != SUBREG
|| GET_CODE (SUBREG_REG (dest
)) != REG
))
102 if (GET_CODE (dest
) == SUBREG
)
103 first_regno
= subreg_regno (dest
);
105 first_regno
= REGNO (dest
);
107 last_regno
= first_regno
+ HARD_REGNO_NREGS (first_regno
, GET_MODE (dest
));
109 if (GET_CODE (x
) == CLOBBER
)
110 for (i
= first_regno
; i
< last_regno
; i
++)
111 CLEAR_HARD_REG_BIT (current_live_regs
, i
);
113 for (i
= first_regno
; i
< last_regno
; i
++)
115 SET_HARD_REG_BIT (current_live_regs
, i
);
116 CLEAR_HARD_REG_BIT (pending_dead_regs
, i
);
120 /* Find the number of the basic block with correct live register
121 information that starts closest to INSN. Return -1 if we couldn't
122 find such a basic block or the beginning is more than
123 SEARCH_LIMIT instructions before INSN. Use SEARCH_LIMIT = -1 for
126 The delay slot filling code destroys the control-flow graph so,
127 instead of finding the basic block containing INSN, we search
128 backwards toward a BARRIER where the live register information is
132 find_basic_block (rtx insn
, int search_limit
)
136 /* Scan backwards to the previous BARRIER. Then see if we can find a
137 label that starts a basic block. Return the basic block number. */
138 for (insn
= prev_nonnote_insn (insn
);
139 insn
&& GET_CODE (insn
) != BARRIER
&& search_limit
!= 0;
140 insn
= prev_nonnote_insn (insn
), --search_limit
)
143 /* The closest BARRIER is too far away. */
144 if (search_limit
== 0)
147 /* The start of the function. */
149 return ENTRY_BLOCK_PTR
->next_bb
->index
;
151 /* See if any of the upcoming CODE_LABELs start a basic block. If we reach
152 anything other than a CODE_LABEL or note, we can't find this code. */
153 for (insn
= next_nonnote_insn (insn
);
154 insn
&& GET_CODE (insn
) == CODE_LABEL
;
155 insn
= next_nonnote_insn (insn
))
158 if (insn
== BB_HEAD (bb
))
165 /* Similar to next_insn, but ignores insns in the delay slots of
166 an annulled branch. */
169 next_insn_no_annul (rtx insn
)
173 /* If INSN is an annulled branch, skip any insns from the target
175 if ((GET_CODE (insn
) == JUMP_INSN
176 || GET_CODE (insn
) == CALL_INSN
177 || GET_CODE (insn
) == INSN
)
178 && INSN_ANNULLED_BRANCH_P (insn
)
179 && NEXT_INSN (PREV_INSN (insn
)) != insn
)
181 rtx next
= NEXT_INSN (insn
);
182 enum rtx_code code
= GET_CODE (next
);
184 while ((code
== INSN
|| code
== JUMP_INSN
|| code
== CALL_INSN
)
185 && INSN_FROM_TARGET_P (next
))
188 next
= NEXT_INSN (insn
);
189 code
= GET_CODE (next
);
193 insn
= NEXT_INSN (insn
);
194 if (insn
&& GET_CODE (insn
) == INSN
195 && GET_CODE (PATTERN (insn
)) == SEQUENCE
)
196 insn
= XVECEXP (PATTERN (insn
), 0, 0);
202 /* Given X, some rtl, and RES, a pointer to a `struct resource', mark
203 which resources are referenced by the insn. If INCLUDE_DELAYED_EFFECTS
204 is TRUE, resources used by the called routine will be included for
208 mark_referenced_resources (rtx x
, struct resources
*res
,
209 int include_delayed_effects
)
211 enum rtx_code code
= GET_CODE (x
);
214 const char *format_ptr
;
216 /* Handle leaf items for which we set resource flags. Also, special-case
217 CALL, SET and CLOBBER operators. */
230 if (GET_CODE (SUBREG_REG (x
)) != REG
)
231 mark_referenced_resources (SUBREG_REG (x
), res
, 0);
234 unsigned int regno
= subreg_regno (x
);
235 unsigned int last_regno
236 = regno
+ HARD_REGNO_NREGS (regno
, GET_MODE (x
));
238 if (last_regno
> FIRST_PSEUDO_REGISTER
)
240 for (r
= regno
; r
< last_regno
; r
++)
241 SET_HARD_REG_BIT (res
->regs
, r
);
247 unsigned int regno
= REGNO (x
);
248 unsigned int last_regno
249 = regno
+ HARD_REGNO_NREGS (regno
, GET_MODE (x
));
251 if (last_regno
> FIRST_PSEUDO_REGISTER
)
253 for (r
= regno
; r
< last_regno
; r
++)
254 SET_HARD_REG_BIT (res
->regs
, r
);
259 /* If this memory shouldn't change, it really isn't referencing
261 if (RTX_UNCHANGING_P (x
))
262 res
->unch_memory
= 1;
265 res
->volatil
|= MEM_VOLATILE_P (x
);
267 /* Mark registers used to access memory. */
268 mark_referenced_resources (XEXP (x
, 0), res
, 0);
275 case UNSPEC_VOLATILE
:
277 /* Traditional asm's are always volatile. */
286 res
->volatil
|= MEM_VOLATILE_P (x
);
288 /* For all ASM_OPERANDS, we must traverse the vector of input operands.
289 We can not just fall through here since then we would be confused
290 by the ASM_INPUT rtx inside ASM_OPERANDS, which do not indicate
291 traditional asms unlike their normal usage. */
293 for (i
= 0; i
< ASM_OPERANDS_INPUT_LENGTH (x
); i
++)
294 mark_referenced_resources (ASM_OPERANDS_INPUT (x
, i
), res
, 0);
298 /* The first operand will be a (MEM (xxx)) but doesn't really reference
299 memory. The second operand may be referenced, though. */
300 mark_referenced_resources (XEXP (XEXP (x
, 0), 0), res
, 0);
301 mark_referenced_resources (XEXP (x
, 1), res
, 0);
305 /* Usually, the first operand of SET is set, not referenced. But
306 registers used to access memory are referenced. SET_DEST is
307 also referenced if it is a ZERO_EXTRACT or SIGN_EXTRACT. */
309 mark_referenced_resources (SET_SRC (x
), res
, 0);
312 if (GET_CODE (x
) == SIGN_EXTRACT
313 || GET_CODE (x
) == ZERO_EXTRACT
314 || GET_CODE (x
) == STRICT_LOW_PART
)
315 mark_referenced_resources (x
, res
, 0);
316 else if (GET_CODE (x
) == SUBREG
)
318 if (GET_CODE (x
) == MEM
)
319 mark_referenced_resources (XEXP (x
, 0), res
, 0);
326 if (include_delayed_effects
)
328 /* A CALL references memory, the frame pointer if it exists, the
329 stack pointer, any global registers and any registers given in
330 USE insns immediately in front of the CALL.
332 However, we may have moved some of the parameter loading insns
333 into the delay slot of this CALL. If so, the USE's for them
334 don't count and should be skipped. */
335 rtx insn
= PREV_INSN (x
);
340 /* If we are part of a delay slot sequence, point at the SEQUENCE. */
341 if (NEXT_INSN (insn
) != x
)
343 sequence
= PATTERN (NEXT_INSN (insn
));
344 seq_size
= XVECLEN (sequence
, 0);
345 if (GET_CODE (sequence
) != SEQUENCE
)
350 SET_HARD_REG_BIT (res
->regs
, STACK_POINTER_REGNUM
);
351 if (frame_pointer_needed
)
353 SET_HARD_REG_BIT (res
->regs
, FRAME_POINTER_REGNUM
);
354 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
355 SET_HARD_REG_BIT (res
->regs
, HARD_FRAME_POINTER_REGNUM
);
359 for (i
= 0; i
< FIRST_PSEUDO_REGISTER
; i
++)
361 SET_HARD_REG_BIT (res
->regs
, i
);
363 /* Check for a REG_SETJMP. If it exists, then we must
364 assume that this call can need any register.
366 This is done to be more conservative about how we handle setjmp.
367 We assume that they both use and set all registers. Using all
368 registers ensures that a register will not be considered dead
369 just because it crosses a setjmp call. A register should be
370 considered dead only if the setjmp call returns nonzero. */
371 if (find_reg_note (x
, REG_SETJMP
, NULL
))
372 SET_HARD_REG_SET (res
->regs
);
377 for (link
= CALL_INSN_FUNCTION_USAGE (x
);
379 link
= XEXP (link
, 1))
380 if (GET_CODE (XEXP (link
, 0)) == USE
)
382 for (i
= 1; i
< seq_size
; i
++)
384 rtx slot_pat
= PATTERN (XVECEXP (sequence
, 0, i
));
385 if (GET_CODE (slot_pat
) == SET
386 && rtx_equal_p (SET_DEST (slot_pat
),
387 XEXP (XEXP (link
, 0), 0)))
391 mark_referenced_resources (XEXP (XEXP (link
, 0), 0),
397 /* ... fall through to other INSN processing ... */
402 #ifdef INSN_REFERENCES_ARE_DELAYED
403 if (! include_delayed_effects
404 && INSN_REFERENCES_ARE_DELAYED (x
))
408 /* No special processing, just speed up. */
409 mark_referenced_resources (PATTERN (x
), res
, include_delayed_effects
);
416 /* Process each sub-expression and flag what it needs. */
417 format_ptr
= GET_RTX_FORMAT (code
);
418 for (i
= 0; i
< GET_RTX_LENGTH (code
); i
++)
419 switch (*format_ptr
++)
422 mark_referenced_resources (XEXP (x
, i
), res
, include_delayed_effects
);
426 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
427 mark_referenced_resources (XVECEXP (x
, i
, j
), res
,
428 include_delayed_effects
);
433 /* A subroutine of mark_target_live_regs. Search forward from TARGET
434 looking for registers that are set before they are used. These are dead.
435 Stop after passing a few conditional jumps, and/or a small
436 number of unconditional branches. */
439 find_dead_or_set_registers (rtx target
, struct resources
*res
,
440 rtx
*jump_target
, int jump_count
,
441 struct resources set
, struct resources needed
)
443 HARD_REG_SET scratch
;
448 for (insn
= target
; insn
; insn
= next
)
450 rtx this_jump_insn
= insn
;
452 next
= NEXT_INSN (insn
);
454 /* If this instruction can throw an exception, then we don't
455 know where we might end up next. That means that we have to
456 assume that whatever we have already marked as live really is
458 if (can_throw_internal (insn
))
461 switch (GET_CODE (insn
))
464 /* After a label, any pending dead registers that weren't yet
465 used can be made dead. */
466 AND_COMPL_HARD_REG_SET (pending_dead_regs
, needed
.regs
);
467 AND_COMPL_HARD_REG_SET (res
->regs
, pending_dead_regs
);
468 CLEAR_HARD_REG_SET (pending_dead_regs
);
477 if (GET_CODE (PATTERN (insn
)) == USE
)
479 /* If INSN is a USE made by update_block, we care about the
480 underlying insn. Any registers set by the underlying insn
481 are live since the insn is being done somewhere else. */
482 if (INSN_P (XEXP (PATTERN (insn
), 0)))
483 mark_set_resources (XEXP (PATTERN (insn
), 0), res
, 0,
486 /* All other USE insns are to be ignored. */
489 else if (GET_CODE (PATTERN (insn
)) == CLOBBER
)
491 else if (GET_CODE (PATTERN (insn
)) == SEQUENCE
)
493 /* An unconditional jump can be used to fill the delay slot
494 of a call, so search for a JUMP_INSN in any position. */
495 for (i
= 0; i
< XVECLEN (PATTERN (insn
), 0); i
++)
497 this_jump_insn
= XVECEXP (PATTERN (insn
), 0, i
);
498 if (GET_CODE (this_jump_insn
) == JUMP_INSN
)
507 if (GET_CODE (this_jump_insn
) == JUMP_INSN
)
509 if (jump_count
++ < 10)
511 if (any_uncondjump_p (this_jump_insn
)
512 || GET_CODE (PATTERN (this_jump_insn
)) == RETURN
)
514 next
= JUMP_LABEL (this_jump_insn
);
519 *jump_target
= JUMP_LABEL (this_jump_insn
);
522 else if (any_condjump_p (this_jump_insn
))
524 struct resources target_set
, target_res
;
525 struct resources fallthrough_res
;
527 /* We can handle conditional branches here by following
528 both paths, and then IOR the results of the two paths
529 together, which will give us registers that are dead
530 on both paths. Since this is expensive, we give it
531 a much higher cost than unconditional branches. The
532 cost was chosen so that we will follow at most 1
533 conditional branch. */
536 if (jump_count
>= 10)
539 mark_referenced_resources (insn
, &needed
, 1);
541 /* For an annulled branch, mark_set_resources ignores slots
542 filled by instructions from the target. This is correct
543 if the branch is not taken. Since we are following both
544 paths from the branch, we must also compute correct info
545 if the branch is taken. We do this by inverting all of
546 the INSN_FROM_TARGET_P bits, calling mark_set_resources,
547 and then inverting the INSN_FROM_TARGET_P bits again. */
549 if (GET_CODE (PATTERN (insn
)) == SEQUENCE
550 && INSN_ANNULLED_BRANCH_P (this_jump_insn
))
552 for (i
= 1; i
< XVECLEN (PATTERN (insn
), 0); i
++)
553 INSN_FROM_TARGET_P (XVECEXP (PATTERN (insn
), 0, i
))
554 = ! INSN_FROM_TARGET_P (XVECEXP (PATTERN (insn
), 0, i
));
557 mark_set_resources (insn
, &target_set
, 0,
560 for (i
= 1; i
< XVECLEN (PATTERN (insn
), 0); i
++)
561 INSN_FROM_TARGET_P (XVECEXP (PATTERN (insn
), 0, i
))
562 = ! INSN_FROM_TARGET_P (XVECEXP (PATTERN (insn
), 0, i
));
564 mark_set_resources (insn
, &set
, 0, MARK_SRC_DEST_CALL
);
568 mark_set_resources (insn
, &set
, 0, MARK_SRC_DEST_CALL
);
573 COPY_HARD_REG_SET (scratch
, target_set
.regs
);
574 AND_COMPL_HARD_REG_SET (scratch
, needed
.regs
);
575 AND_COMPL_HARD_REG_SET (target_res
.regs
, scratch
);
577 fallthrough_res
= *res
;
578 COPY_HARD_REG_SET (scratch
, set
.regs
);
579 AND_COMPL_HARD_REG_SET (scratch
, needed
.regs
);
580 AND_COMPL_HARD_REG_SET (fallthrough_res
.regs
, scratch
);
582 find_dead_or_set_registers (JUMP_LABEL (this_jump_insn
),
583 &target_res
, 0, jump_count
,
585 find_dead_or_set_registers (next
,
586 &fallthrough_res
, 0, jump_count
,
588 IOR_HARD_REG_SET (fallthrough_res
.regs
, target_res
.regs
);
589 AND_HARD_REG_SET (res
->regs
, fallthrough_res
.regs
);
597 /* Don't try this optimization if we expired our jump count
598 above, since that would mean there may be an infinite loop
599 in the function being compiled. */
605 mark_referenced_resources (insn
, &needed
, 1);
606 mark_set_resources (insn
, &set
, 0, MARK_SRC_DEST_CALL
);
608 COPY_HARD_REG_SET (scratch
, set
.regs
);
609 AND_COMPL_HARD_REG_SET (scratch
, needed
.regs
);
610 AND_COMPL_HARD_REG_SET (res
->regs
, scratch
);
616 /* Given X, a part of an insn, and a pointer to a `struct resource',
617 RES, indicate which resources are modified by the insn. If
618 MARK_TYPE is MARK_SRC_DEST_CALL, also mark resources potentially
619 set by the called routine.
621 If IN_DEST is nonzero, it means we are inside a SET. Otherwise,
622 objects are being referenced instead of set.
624 We never mark the insn as modifying the condition code unless it explicitly
625 SETs CC0 even though this is not totally correct. The reason for this is
626 that we require a SET of CC0 to immediately precede the reference to CC0.
627 So if some other insn sets CC0 as a side-effect, we know it cannot affect
628 our computation and thus may be placed in a delay slot. */
631 mark_set_resources (rtx x
, struct resources
*res
, int in_dest
,
632 enum mark_resource_type mark_type
)
637 const char *format_ptr
;
656 /* These don't set any resources. */
665 /* Called routine modifies the condition code, memory, any registers
666 that aren't saved across calls, global registers and anything
667 explicitly CLOBBERed immediately after the CALL_INSN. */
669 if (mark_type
== MARK_SRC_DEST_CALL
)
673 res
->cc
= res
->memory
= 1;
674 for (r
= 0; r
< FIRST_PSEUDO_REGISTER
; r
++)
675 if (call_used_regs
[r
] || global_regs
[r
])
676 SET_HARD_REG_BIT (res
->regs
, r
);
678 for (link
= CALL_INSN_FUNCTION_USAGE (x
);
679 link
; link
= XEXP (link
, 1))
680 if (GET_CODE (XEXP (link
, 0)) == CLOBBER
)
681 mark_set_resources (SET_DEST (XEXP (link
, 0)), res
, 1,
684 /* Check for a REG_SETJMP. If it exists, then we must
685 assume that this call can clobber any register. */
686 if (find_reg_note (x
, REG_SETJMP
, NULL
))
687 SET_HARD_REG_SET (res
->regs
);
690 /* ... and also what its RTL says it modifies, if anything. */
695 /* An insn consisting of just a CLOBBER (or USE) is just for flow
696 and doesn't actually do anything, so we ignore it. */
698 #ifdef INSN_SETS_ARE_DELAYED
699 if (mark_type
!= MARK_SRC_DEST_CALL
700 && INSN_SETS_ARE_DELAYED (x
))
705 if (GET_CODE (x
) != USE
&& GET_CODE (x
) != CLOBBER
)
710 /* If the source of a SET is a CALL, this is actually done by
711 the called routine. So only include it if we are to include the
712 effects of the calling routine. */
714 mark_set_resources (SET_DEST (x
), res
,
715 (mark_type
== MARK_SRC_DEST_CALL
716 || GET_CODE (SET_SRC (x
)) != CALL
),
719 mark_set_resources (SET_SRC (x
), res
, 0, MARK_SRC_DEST
);
723 mark_set_resources (XEXP (x
, 0), res
, 1, MARK_SRC_DEST
);
727 for (i
= 0; i
< XVECLEN (x
, 0); i
++)
728 if (! (INSN_ANNULLED_BRANCH_P (XVECEXP (x
, 0, 0))
729 && INSN_FROM_TARGET_P (XVECEXP (x
, 0, i
))))
730 mark_set_resources (XVECEXP (x
, 0, i
), res
, 0, mark_type
);
737 mark_set_resources (XEXP (x
, 0), res
, 1, MARK_SRC_DEST
);
742 mark_set_resources (XEXP (x
, 0), res
, 1, MARK_SRC_DEST
);
743 mark_set_resources (XEXP (XEXP (x
, 1), 0), res
, 0, MARK_SRC_DEST
);
744 mark_set_resources (XEXP (XEXP (x
, 1), 1), res
, 0, MARK_SRC_DEST
);
749 mark_set_resources (XEXP (x
, 0), res
, in_dest
, MARK_SRC_DEST
);
750 mark_set_resources (XEXP (x
, 1), res
, 0, MARK_SRC_DEST
);
751 mark_set_resources (XEXP (x
, 2), res
, 0, MARK_SRC_DEST
);
758 res
->unch_memory
|= RTX_UNCHANGING_P (x
);
759 res
->volatil
|= MEM_VOLATILE_P (x
);
762 mark_set_resources (XEXP (x
, 0), res
, 0, MARK_SRC_DEST
);
768 if (GET_CODE (SUBREG_REG (x
)) != REG
)
769 mark_set_resources (SUBREG_REG (x
), res
, in_dest
, mark_type
);
772 unsigned int regno
= subreg_regno (x
);
773 unsigned int last_regno
774 = regno
+ HARD_REGNO_NREGS (regno
, GET_MODE (x
));
776 if (last_regno
> FIRST_PSEUDO_REGISTER
)
778 for (r
= regno
; r
< last_regno
; r
++)
779 SET_HARD_REG_BIT (res
->regs
, r
);
787 unsigned int regno
= REGNO (x
);
788 unsigned int last_regno
789 = regno
+ HARD_REGNO_NREGS (regno
, GET_MODE (x
));
791 if (last_regno
> FIRST_PSEUDO_REGISTER
)
793 for (r
= regno
; r
< last_regno
; r
++)
794 SET_HARD_REG_BIT (res
->regs
, r
);
798 case UNSPEC_VOLATILE
:
800 /* Traditional asm's are always volatile. */
809 res
->volatil
|= MEM_VOLATILE_P (x
);
811 /* For all ASM_OPERANDS, we must traverse the vector of input operands.
812 We can not just fall through here since then we would be confused
813 by the ASM_INPUT rtx inside ASM_OPERANDS, which do not indicate
814 traditional asms unlike their normal usage. */
816 for (i
= 0; i
< ASM_OPERANDS_INPUT_LENGTH (x
); i
++)
817 mark_set_resources (ASM_OPERANDS_INPUT (x
, i
), res
, in_dest
,
825 /* Process each sub-expression and flag what it needs. */
826 format_ptr
= GET_RTX_FORMAT (code
);
827 for (i
= 0; i
< GET_RTX_LENGTH (code
); i
++)
828 switch (*format_ptr
++)
831 mark_set_resources (XEXP (x
, i
), res
, in_dest
, mark_type
);
835 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
836 mark_set_resources (XVECEXP (x
, i
, j
), res
, in_dest
, mark_type
);
841 /* Set the resources that are live at TARGET.
843 If TARGET is zero, we refer to the end of the current function and can
844 return our precomputed value.
846 Otherwise, we try to find out what is live by consulting the basic block
847 information. This is tricky, because we must consider the actions of
848 reload and jump optimization, which occur after the basic block information
851 Accordingly, we proceed as follows::
853 We find the previous BARRIER and look at all immediately following labels
854 (with no intervening active insns) to see if any of them start a basic
855 block. If we hit the start of the function first, we use block 0.
857 Once we have found a basic block and a corresponding first insns, we can
858 accurately compute the live status from basic_block_live_regs and
859 reg_renumber. (By starting at a label following a BARRIER, we are immune
860 to actions taken by reload and jump.) Then we scan all insns between
861 that point and our target. For each CLOBBER (or for call-clobbered regs
862 when we pass a CALL_INSN), mark the appropriate registers are dead. For
863 a SET, mark them as live.
865 We have to be careful when using REG_DEAD notes because they are not
866 updated by such things as find_equiv_reg. So keep track of registers
867 marked as dead that haven't been assigned to, and mark them dead at the
868 next CODE_LABEL since reload and jump won't propagate values across labels.
870 If we cannot find the start of a basic block (should be a very rare
871 case, if it can happen at all), mark everything as potentially live.
873 Next, scan forward from TARGET looking for things set or clobbered
874 before they are used. These are not live.
876 Because we can be called many times on the same target, save our results
877 in a hash table indexed by INSN_UID. This is only done if the function
878 init_resource_info () was invoked before we are called. */
881 mark_target_live_regs (rtx insns
, rtx target
, struct resources
*res
)
885 struct target_info
*tinfo
= NULL
;
889 HARD_REG_SET scratch
;
890 struct resources set
, needed
;
892 /* Handle end of function. */
895 *res
= end_of_function_needs
;
899 /* We have to assume memory is needed, but the CC isn't. */
901 res
->volatil
= res
->unch_memory
= 0;
904 /* See if we have computed this value already. */
905 if (target_hash_table
!= NULL
)
907 for (tinfo
= target_hash_table
[INSN_UID (target
) % TARGET_HASH_PRIME
];
908 tinfo
; tinfo
= tinfo
->next
)
909 if (tinfo
->uid
== INSN_UID (target
))
912 /* Start by getting the basic block number. If we have saved
913 information, we can get it from there unless the insn at the
914 start of the basic block has been deleted. */
915 if (tinfo
&& tinfo
->block
!= -1
916 && ! INSN_DELETED_P (BB_HEAD (BASIC_BLOCK (tinfo
->block
))))
921 b
= find_basic_block (target
, MAX_DELAY_SLOT_LIVE_SEARCH
);
923 if (target_hash_table
!= NULL
)
927 /* If the information is up-to-date, use it. Otherwise, we will
929 if (b
== tinfo
->block
&& b
!= -1 && tinfo
->bb_tick
== bb_ticks
[b
])
931 COPY_HARD_REG_SET (res
->regs
, tinfo
->live_regs
);
937 /* Allocate a place to put our results and chain it into the
939 tinfo
= xmalloc (sizeof (struct target_info
));
940 tinfo
->uid
= INSN_UID (target
);
943 = target_hash_table
[INSN_UID (target
) % TARGET_HASH_PRIME
];
944 target_hash_table
[INSN_UID (target
) % TARGET_HASH_PRIME
] = tinfo
;
948 CLEAR_HARD_REG_SET (pending_dead_regs
);
950 /* If we found a basic block, get the live registers from it and update
951 them with anything set or killed between its start and the insn before
952 TARGET. Otherwise, we must assume everything is live. */
955 regset regs_live
= BASIC_BLOCK (b
)->global_live_at_start
;
958 rtx start_insn
, stop_insn
;
960 /* Compute hard regs live at start of block -- this is the real hard regs
961 marked live, plus live pseudo regs that have been renumbered to
964 REG_SET_TO_HARD_REG_SET (current_live_regs
, regs_live
);
966 EXECUTE_IF_SET_IN_REG_SET
967 (regs_live
, FIRST_PSEUDO_REGISTER
, i
,
969 if (reg_renumber
[i
] >= 0)
971 regno
= reg_renumber
[i
];
973 j
< regno
+ HARD_REGNO_NREGS (regno
,
974 PSEUDO_REGNO_MODE (i
));
976 SET_HARD_REG_BIT (current_live_regs
, j
);
980 /* Get starting and ending insn, handling the case where each might
982 start_insn
= (b
== 0 ? insns
: BB_HEAD (BASIC_BLOCK (b
)));
985 if (GET_CODE (start_insn
) == INSN
986 && GET_CODE (PATTERN (start_insn
)) == SEQUENCE
)
987 start_insn
= XVECEXP (PATTERN (start_insn
), 0, 0);
989 if (GET_CODE (stop_insn
) == INSN
990 && GET_CODE (PATTERN (stop_insn
)) == SEQUENCE
)
991 stop_insn
= next_insn (PREV_INSN (stop_insn
));
993 for (insn
= start_insn
; insn
!= stop_insn
;
994 insn
= next_insn_no_annul (insn
))
997 rtx real_insn
= insn
;
998 enum rtx_code code
= GET_CODE (insn
);
1000 /* If this insn is from the target of a branch, it isn't going to
1001 be used in the sequel. If it is used in both cases, this
1002 test will not be true. */
1003 if ((code
== INSN
|| code
== JUMP_INSN
|| code
== CALL_INSN
)
1004 && INSN_FROM_TARGET_P (insn
))
1007 /* If this insn is a USE made by update_block, we care about the
1009 if (code
== INSN
&& GET_CODE (PATTERN (insn
)) == USE
1010 && INSN_P (XEXP (PATTERN (insn
), 0)))
1011 real_insn
= XEXP (PATTERN (insn
), 0);
1013 if (GET_CODE (real_insn
) == CALL_INSN
)
1015 /* CALL clobbers all call-used regs that aren't fixed except
1016 sp, ap, and fp. Do this before setting the result of the
1018 AND_COMPL_HARD_REG_SET (current_live_regs
,
1019 regs_invalidated_by_call
);
1021 /* A CALL_INSN sets any global register live, since it may
1022 have been modified by the call. */
1023 for (i
= 0; i
< FIRST_PSEUDO_REGISTER
; i
++)
1025 SET_HARD_REG_BIT (current_live_regs
, i
);
1028 /* Mark anything killed in an insn to be deadened at the next
1029 label. Ignore USE insns; the only REG_DEAD notes will be for
1030 parameters. But they might be early. A CALL_INSN will usually
1031 clobber registers used for parameters. It isn't worth bothering
1032 with the unlikely case when it won't. */
1033 if ((GET_CODE (real_insn
) == INSN
1034 && GET_CODE (PATTERN (real_insn
)) != USE
1035 && GET_CODE (PATTERN (real_insn
)) != CLOBBER
)
1036 || GET_CODE (real_insn
) == JUMP_INSN
1037 || GET_CODE (real_insn
) == CALL_INSN
)
1039 for (link
= REG_NOTES (real_insn
); link
; link
= XEXP (link
, 1))
1040 if (REG_NOTE_KIND (link
) == REG_DEAD
1041 && GET_CODE (XEXP (link
, 0)) == REG
1042 && REGNO (XEXP (link
, 0)) < FIRST_PSEUDO_REGISTER
)
1044 unsigned int first_regno
= REGNO (XEXP (link
, 0));
1045 unsigned int last_regno
1047 + HARD_REGNO_NREGS (first_regno
,
1048 GET_MODE (XEXP (link
, 0))));
1050 for (i
= first_regno
; i
< last_regno
; i
++)
1051 SET_HARD_REG_BIT (pending_dead_regs
, i
);
1054 note_stores (PATTERN (real_insn
), update_live_status
, NULL
);
1056 /* If any registers were unused after this insn, kill them.
1057 These notes will always be accurate. */
1058 for (link
= REG_NOTES (real_insn
); link
; link
= XEXP (link
, 1))
1059 if (REG_NOTE_KIND (link
) == REG_UNUSED
1060 && GET_CODE (XEXP (link
, 0)) == REG
1061 && REGNO (XEXP (link
, 0)) < FIRST_PSEUDO_REGISTER
)
1063 unsigned int first_regno
= REGNO (XEXP (link
, 0));
1064 unsigned int last_regno
1066 + HARD_REGNO_NREGS (first_regno
,
1067 GET_MODE (XEXP (link
, 0))));
1069 for (i
= first_regno
; i
< last_regno
; i
++)
1070 CLEAR_HARD_REG_BIT (current_live_regs
, i
);
1074 else if (GET_CODE (real_insn
) == CODE_LABEL
)
1076 /* A label clobbers the pending dead registers since neither
1077 reload nor jump will propagate a value across a label. */
1078 AND_COMPL_HARD_REG_SET (current_live_regs
, pending_dead_regs
);
1079 CLEAR_HARD_REG_SET (pending_dead_regs
);
1082 /* The beginning of the epilogue corresponds to the end of the
1083 RTL chain when there are no epilogue insns. Certain resources
1084 are implicitly required at that point. */
1085 else if (GET_CODE (real_insn
) == NOTE
1086 && NOTE_LINE_NUMBER (real_insn
) == NOTE_INSN_EPILOGUE_BEG
)
1087 IOR_HARD_REG_SET (current_live_regs
, start_of_epilogue_needs
.regs
);
1090 COPY_HARD_REG_SET (res
->regs
, current_live_regs
);
1094 tinfo
->bb_tick
= bb_ticks
[b
];
1098 /* We didn't find the start of a basic block. Assume everything
1099 in use. This should happen only extremely rarely. */
1100 SET_HARD_REG_SET (res
->regs
);
1102 CLEAR_RESOURCE (&set
);
1103 CLEAR_RESOURCE (&needed
);
1105 jump_insn
= find_dead_or_set_registers (target
, res
, &jump_target
, 0,
1108 /* If we hit an unconditional branch, we have another way of finding out
1109 what is live: we can see what is live at the branch target and include
1110 anything used but not set before the branch. We add the live
1111 resources found using the test below to those found until now. */
1115 struct resources new_resources
;
1116 rtx stop_insn
= next_active_insn (jump_insn
);
1118 mark_target_live_regs (insns
, next_active_insn (jump_target
),
1120 CLEAR_RESOURCE (&set
);
1121 CLEAR_RESOURCE (&needed
);
1123 /* Include JUMP_INSN in the needed registers. */
1124 for (insn
= target
; insn
!= stop_insn
; insn
= next_active_insn (insn
))
1126 mark_referenced_resources (insn
, &needed
, 1);
1128 COPY_HARD_REG_SET (scratch
, needed
.regs
);
1129 AND_COMPL_HARD_REG_SET (scratch
, set
.regs
);
1130 IOR_HARD_REG_SET (new_resources
.regs
, scratch
);
1132 mark_set_resources (insn
, &set
, 0, MARK_SRC_DEST_CALL
);
1135 IOR_HARD_REG_SET (res
->regs
, new_resources
.regs
);
1140 COPY_HARD_REG_SET (tinfo
->live_regs
, res
->regs
);
1144 /* Initialize the resources required by mark_target_live_regs ().
1145 This should be invoked before the first call to mark_target_live_regs. */
1148 init_resource_info (rtx epilogue_insn
)
1152 /* Indicate what resources are required to be valid at the end of the current
1153 function. The condition code never is and memory always is. If the
1154 frame pointer is needed, it is and so is the stack pointer unless
1155 EXIT_IGNORE_STACK is nonzero. If the frame pointer is not needed, the
1156 stack pointer is. Registers used to return the function value are
1157 needed. Registers holding global variables are needed. */
1159 end_of_function_needs
.cc
= 0;
1160 end_of_function_needs
.memory
= 1;
1161 end_of_function_needs
.unch_memory
= 0;
1162 CLEAR_HARD_REG_SET (end_of_function_needs
.regs
);
1164 if (frame_pointer_needed
)
1166 SET_HARD_REG_BIT (end_of_function_needs
.regs
, FRAME_POINTER_REGNUM
);
1167 #if HARD_FRAME_POINTER_REGNUM != FRAME_POINTER_REGNUM
1168 SET_HARD_REG_BIT (end_of_function_needs
.regs
, HARD_FRAME_POINTER_REGNUM
);
1170 #ifdef EXIT_IGNORE_STACK
1171 if (! EXIT_IGNORE_STACK
1172 || current_function_sp_is_unchanging
)
1174 SET_HARD_REG_BIT (end_of_function_needs
.regs
, STACK_POINTER_REGNUM
);
1177 SET_HARD_REG_BIT (end_of_function_needs
.regs
, STACK_POINTER_REGNUM
);
1179 if (current_function_return_rtx
!= 0)
1180 mark_referenced_resources (current_function_return_rtx
,
1181 &end_of_function_needs
, 1);
1183 for (i
= 0; i
< FIRST_PSEUDO_REGISTER
; i
++)
1185 #ifdef EPILOGUE_USES
1186 || EPILOGUE_USES (i
)
1189 SET_HARD_REG_BIT (end_of_function_needs
.regs
, i
);
1191 /* The registers required to be live at the end of the function are
1192 represented in the flow information as being dead just prior to
1193 reaching the end of the function. For example, the return of a value
1194 might be represented by a USE of the return register immediately
1195 followed by an unconditional jump to the return label where the
1196 return label is the end of the RTL chain. The end of the RTL chain
1197 is then taken to mean that the return register is live.
1199 This sequence is no longer maintained when epilogue instructions are
1200 added to the RTL chain. To reconstruct the original meaning, the
1201 start of the epilogue (NOTE_INSN_EPILOGUE_BEG) is regarded as the
1202 point where these registers become live (start_of_epilogue_needs).
1203 If epilogue instructions are present, the registers set by those
1204 instructions won't have been processed by flow. Thus, those
1205 registers are additionally required at the end of the RTL chain
1206 (end_of_function_needs). */
1208 start_of_epilogue_needs
= end_of_function_needs
;
1210 while ((epilogue_insn
= next_nonnote_insn (epilogue_insn
)))
1211 mark_set_resources (epilogue_insn
, &end_of_function_needs
, 0,
1212 MARK_SRC_DEST_CALL
);
1214 /* Allocate and initialize the tables used by mark_target_live_regs. */
1215 target_hash_table
= xcalloc (TARGET_HASH_PRIME
, sizeof (struct target_info
*));
1216 bb_ticks
= xcalloc (last_basic_block
, sizeof (int));
1219 /* Free up the resources allocated to mark_target_live_regs (). This
1220 should be invoked after the last call to mark_target_live_regs (). */
1223 free_resource_info (void)
1225 if (target_hash_table
!= NULL
)
1229 for (i
= 0; i
< TARGET_HASH_PRIME
; ++i
)
1231 struct target_info
*ti
= target_hash_table
[i
];
1235 struct target_info
*next
= ti
->next
;
1241 free (target_hash_table
);
1242 target_hash_table
= NULL
;
1245 if (bb_ticks
!= NULL
)
1252 /* Clear any hashed information that we have stored for INSN. */
1255 clear_hashed_info_for_insn (rtx insn
)
1257 struct target_info
*tinfo
;
1259 if (target_hash_table
!= NULL
)
1261 for (tinfo
= target_hash_table
[INSN_UID (insn
) % TARGET_HASH_PRIME
];
1262 tinfo
; tinfo
= tinfo
->next
)
1263 if (tinfo
->uid
== INSN_UID (insn
))
1271 /* Increment the tick count for the basic block that contains INSN. */
1274 incr_ticks_for_insn (rtx insn
)
1276 int b
= find_basic_block (insn
, MAX_DELAY_SLOT_LIVE_SEARCH
);
1282 /* Add TRIAL to the set of resources used at the end of the current
1285 mark_end_of_function_resources (rtx trial
, int include_delayed_effects
)
1287 mark_referenced_resources (trial
, &end_of_function_needs
,
1288 include_delayed_effects
);