1 /* Definitions for computing resource usage of specific insns.
2 Copyright (C) 1999, 2000 Free Software Foundation, Inc.
4 This file is part of GNU CC.
6 GNU CC is free software; you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by
8 the Free Software Foundation; either version 2, or (at your option)
11 GNU CC is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 GNU General Public License for more details.
16 You should have received a copy of the GNU General Public License
17 along with GNU CC; see the file COPYING. If not, write to
18 the Free Software Foundation, 59 Temple Place - Suite 330,
19 Boston, MA 02111-1307, USA. */
26 #include "hard-reg-set.h"
27 #include "basic-block.h"
33 #include "insn-attr.h"
35 /* This structure is used to record liveness information at the targets or
36 fallthrough insns of branches. We will most likely need the information
37 at targets again, so save them in a hash table rather than recomputing them
42 int uid; /* INSN_UID of target. */
43 struct target_info *next; /* Next info for same hash bucket. */
44 HARD_REG_SET live_regs; /* Registers live at target. */
45 int block; /* Basic block number containing target. */
46 int bb_tick; /* Generation count of basic block info. */
49 #define TARGET_HASH_PRIME 257
51 /* Indicates what resources are required at the beginning of the epilogue. */
52 static struct resources start_of_epilogue_needs;
54 /* Indicates what resources are required at function end. */
55 static struct resources end_of_function_needs;
57 /* Define the hash table itself. */
58 static struct target_info **target_hash_table = NULL;
60 /* For each basic block, we maintain a generation number of its basic
61 block info, which is updated each time we move an insn from the
62 target of a jump. This is the generation number indexed by block
67 /* Marks registers possibly live at the current place being scanned by
68 mark_target_live_regs. Used only by next two function. */
70 static HARD_REG_SET current_live_regs;
72 /* Marks registers for which we have seen a REG_DEAD note but no assignment.
73 Also only used by the next two functions. */
75 static HARD_REG_SET pending_dead_regs;
77 static void update_live_status PARAMS ((rtx, rtx, void *));
78 static int find_basic_block PARAMS ((rtx));
79 static rtx next_insn_no_annul PARAMS ((rtx));
80 static rtx find_dead_or_set_registers PARAMS ((rtx, struct resources*,
81 rtx*, int, struct resources,
84 /* Utility function called from mark_target_live_regs via note_stores.
85 It deadens any CLOBBERed registers and livens any SET registers. */
88 update_live_status (dest, x, data)
91 void *data ATTRIBUTE_UNUSED;
93 int first_regno, last_regno;
96 if (GET_CODE (dest) != REG
97 && (GET_CODE (dest) != SUBREG || GET_CODE (SUBREG_REG (dest)) != REG))
100 if (GET_CODE (dest) == SUBREG)
101 first_regno = REGNO (SUBREG_REG (dest)) + SUBREG_WORD (dest);
103 first_regno = REGNO (dest);
105 last_regno = first_regno + HARD_REGNO_NREGS (first_regno, GET_MODE (dest));
107 if (GET_CODE (x) == CLOBBER)
108 for (i = first_regno; i < last_regno; i++)
109 CLEAR_HARD_REG_BIT (current_live_regs, i);
111 for (i = first_regno; i < last_regno; i++)
113 SET_HARD_REG_BIT (current_live_regs, i);
114 CLEAR_HARD_REG_BIT (pending_dead_regs, i);
117 /* Find the number of the basic block that starts closest to INSN. Return -1
118 if we couldn't find such a basic block. */
121 find_basic_block (insn)
126 /* Scan backwards to the previous BARRIER. Then see if we can find a
127 label that starts a basic block. Return the basic block number. */
129 for (insn = prev_nonnote_insn (insn);
130 insn && GET_CODE (insn) != BARRIER;
131 insn = prev_nonnote_insn (insn))
134 /* The start of the function is basic block zero. */
138 /* See if any of the upcoming CODE_LABELs start a basic block. If we reach
139 anything other than a CODE_LABEL or note, we can't find this code. */
140 for (insn = next_nonnote_insn (insn);
141 insn && GET_CODE (insn) == CODE_LABEL;
142 insn = next_nonnote_insn (insn))
144 for (i = 0; i < n_basic_blocks; i++)
145 if (insn == BLOCK_HEAD (i))
152 /* Similar to next_insn, but ignores insns in the delay slots of
153 an annulled branch. */
156 next_insn_no_annul (insn)
161 /* If INSN is an annulled branch, skip any insns from the target
163 if (INSN_ANNULLED_BRANCH_P (insn)
164 && NEXT_INSN (PREV_INSN (insn)) != insn)
165 while (INSN_FROM_TARGET_P (NEXT_INSN (insn)))
166 insn = NEXT_INSN (insn);
168 insn = NEXT_INSN (insn);
169 if (insn && GET_CODE (insn) == INSN
170 && GET_CODE (PATTERN (insn)) == SEQUENCE)
171 insn = XVECEXP (PATTERN (insn), 0, 0);
177 /* Given X, some rtl, and RES, a pointer to a `struct resource', mark
178 which resources are references by the insn. If INCLUDE_DELAYED_EFFECTS
179 is TRUE, resources used by the called routine will be included for
183 mark_referenced_resources (x, res, include_delayed_effects)
185 register struct resources *res;
186 register int include_delayed_effects;
188 enum rtx_code code = GET_CODE (x);
191 register const char *format_ptr;
193 /* Handle leaf items for which we set resource flags. Also, special-case
194 CALL, SET and CLOBBER operators. */
206 if (GET_CODE (SUBREG_REG (x)) != REG)
207 mark_referenced_resources (SUBREG_REG (x), res, 0);
210 unsigned int regno = REGNO (SUBREG_REG (x)) + SUBREG_WORD (x);
211 unsigned int last_regno
212 = regno + HARD_REGNO_NREGS (regno, GET_MODE (x));
214 for (r = regno; r < last_regno; r++)
215 SET_HARD_REG_BIT (res->regs, r);
220 for (r = 0; r < HARD_REGNO_NREGS (REGNO (x), GET_MODE (x)); r++)
221 SET_HARD_REG_BIT (res->regs, REGNO (x) + r);
225 /* If this memory shouldn't change, it really isn't referencing
227 if (RTX_UNCHANGING_P (x))
228 res->unch_memory = 1;
231 res->volatil |= MEM_VOLATILE_P (x);
233 /* Mark registers used to access memory. */
234 mark_referenced_resources (XEXP (x, 0), res, 0);
241 case UNSPEC_VOLATILE:
243 /* Traditional asm's are always volatile. */
252 res->volatil |= MEM_VOLATILE_P (x);
254 /* For all ASM_OPERANDS, we must traverse the vector of input operands.
255 We can not just fall through here since then we would be confused
256 by the ASM_INPUT rtx inside ASM_OPERANDS, which do not indicate
257 traditional asms unlike their normal usage. */
259 for (i = 0; i < ASM_OPERANDS_INPUT_LENGTH (x); i++)
260 mark_referenced_resources (ASM_OPERANDS_INPUT (x, i), res, 0);
264 /* The first operand will be a (MEM (xxx)) but doesn't really reference
265 memory. The second operand may be referenced, though. */
266 mark_referenced_resources (XEXP (XEXP (x, 0), 0), res, 0);
267 mark_referenced_resources (XEXP (x, 1), res, 0);
271 /* Usually, the first operand of SET is set, not referenced. But
272 registers used to access memory are referenced. SET_DEST is
273 also referenced if it is a ZERO_EXTRACT or SIGN_EXTRACT. */
275 mark_referenced_resources (SET_SRC (x), res, 0);
278 if (GET_CODE (x) == SIGN_EXTRACT
279 || GET_CODE (x) == ZERO_EXTRACT
280 || GET_CODE (x) == STRICT_LOW_PART)
281 mark_referenced_resources (x, res, 0);
282 else if (GET_CODE (x) == SUBREG)
284 if (GET_CODE (x) == MEM)
285 mark_referenced_resources (XEXP (x, 0), res, 0);
292 if (include_delayed_effects)
294 /* A CALL references memory, the frame pointer if it exists, the
295 stack pointer, any global registers and any registers given in
296 USE insns immediately in front of the CALL.
298 However, we may have moved some of the parameter loading insns
299 into the delay slot of this CALL. If so, the USE's for them
300 don't count and should be skipped. */
301 rtx insn = PREV_INSN (x);
304 rtx next = NEXT_INSN (x);
307 /* If we are part of a delay slot sequence, point at the SEQUENCE. */
308 if (NEXT_INSN (insn) != x)
310 next = NEXT_INSN (NEXT_INSN (insn));
311 sequence = PATTERN (NEXT_INSN (insn));
312 seq_size = XVECLEN (sequence, 0);
313 if (GET_CODE (sequence) != SEQUENCE)
318 SET_HARD_REG_BIT (res->regs, STACK_POINTER_REGNUM);
319 if (frame_pointer_needed)
321 SET_HARD_REG_BIT (res->regs, FRAME_POINTER_REGNUM);
322 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
323 SET_HARD_REG_BIT (res->regs, HARD_FRAME_POINTER_REGNUM);
327 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
329 SET_HARD_REG_BIT (res->regs, i);
331 /* Check for a NOTE_INSN_SETJMP. If it exists, then we must
332 assume that this call can need any register.
334 This is done to be more conservative about how we handle setjmp.
335 We assume that they both use and set all registers. Using all
336 registers ensures that a register will not be considered dead
337 just because it crosses a setjmp call. A register should be
338 considered dead only if the setjmp call returns non-zero. */
339 if (next && GET_CODE (next) == NOTE
340 && NOTE_LINE_NUMBER (next) == NOTE_INSN_SETJMP)
341 SET_HARD_REG_SET (res->regs);
346 for (link = CALL_INSN_FUNCTION_USAGE (x);
348 link = XEXP (link, 1))
349 if (GET_CODE (XEXP (link, 0)) == USE)
351 for (i = 1; i < seq_size; i++)
353 rtx slot_pat = PATTERN (XVECEXP (sequence, 0, i));
354 if (GET_CODE (slot_pat) == SET
355 && rtx_equal_p (SET_DEST (slot_pat),
356 XEXP (XEXP (link, 0), 0)))
360 mark_referenced_resources (XEXP (XEXP (link, 0), 0),
366 /* ... fall through to other INSN processing ... */
371 #ifdef INSN_REFERENCES_ARE_DELAYED
372 if (! include_delayed_effects
373 && INSN_REFERENCES_ARE_DELAYED (x))
377 /* No special processing, just speed up. */
378 mark_referenced_resources (PATTERN (x), res, include_delayed_effects);
385 /* Process each sub-expression and flag what it needs. */
386 format_ptr = GET_RTX_FORMAT (code);
387 for (i = 0; i < GET_RTX_LENGTH (code); i++)
388 switch (*format_ptr++)
391 mark_referenced_resources (XEXP (x, i), res, include_delayed_effects);
395 for (j = 0; j < XVECLEN (x, i); j++)
396 mark_referenced_resources (XVECEXP (x, i, j), res,
397 include_delayed_effects);
402 /* A subroutine of mark_target_live_regs. Search forward from TARGET
403 looking for registers that are set before they are used. These are dead.
404 Stop after passing a few conditional jumps, and/or a small
405 number of unconditional branches. */
408 find_dead_or_set_registers (target, res, jump_target, jump_count, set, needed)
410 struct resources *res;
413 struct resources set, needed;
415 HARD_REG_SET scratch;
420 for (insn = target; insn; insn = next)
422 rtx this_jump_insn = insn;
424 next = NEXT_INSN (insn);
426 /* If this instruction can throw an exception, then we don't
427 know where we might end up next. That means that we have to
428 assume that whatever we have already marked as live really is
430 if (can_throw (insn))
433 switch (GET_CODE (insn))
436 /* After a label, any pending dead registers that weren't yet
437 used can be made dead. */
438 AND_COMPL_HARD_REG_SET (pending_dead_regs, needed.regs);
439 AND_COMPL_HARD_REG_SET (res->regs, pending_dead_regs);
440 CLEAR_HARD_REG_SET (pending_dead_regs);
449 if (GET_CODE (PATTERN (insn)) == USE)
451 /* If INSN is a USE made by update_block, we care about the
452 underlying insn. Any registers set by the underlying insn
453 are live since the insn is being done somewhere else. */
454 if (GET_RTX_CLASS (GET_CODE (XEXP (PATTERN (insn), 0))) == 'i')
455 mark_set_resources (XEXP (PATTERN (insn), 0), res, 0,
458 /* All other USE insns are to be ignored. */
461 else if (GET_CODE (PATTERN (insn)) == CLOBBER)
463 else if (GET_CODE (PATTERN (insn)) == SEQUENCE)
465 /* An unconditional jump can be used to fill the delay slot
466 of a call, so search for a JUMP_INSN in any position. */
467 for (i = 0; i < XVECLEN (PATTERN (insn), 0); i++)
469 this_jump_insn = XVECEXP (PATTERN (insn), 0, i);
470 if (GET_CODE (this_jump_insn) == JUMP_INSN)
479 if (GET_CODE (this_jump_insn) == JUMP_INSN)
481 if (jump_count++ < 10)
483 if (any_uncondjump_p (this_jump_insn)
484 || GET_CODE (PATTERN (this_jump_insn)) == RETURN)
486 next = JUMP_LABEL (this_jump_insn);
491 *jump_target = JUMP_LABEL (this_jump_insn);
494 else if (any_condjump_p (this_jump_insn))
496 struct resources target_set, target_res;
497 struct resources fallthrough_res;
499 /* We can handle conditional branches here by following
500 both paths, and then IOR the results of the two paths
501 together, which will give us registers that are dead
502 on both paths. Since this is expensive, we give it
503 a much higher cost than unconditional branches. The
504 cost was chosen so that we will follow at most 1
505 conditional branch. */
508 if (jump_count >= 10)
511 mark_referenced_resources (insn, &needed, 1);
513 /* For an annulled branch, mark_set_resources ignores slots
514 filled by instructions from the target. This is correct
515 if the branch is not taken. Since we are following both
516 paths from the branch, we must also compute correct info
517 if the branch is taken. We do this by inverting all of
518 the INSN_FROM_TARGET_P bits, calling mark_set_resources,
519 and then inverting the INSN_FROM_TARGET_P bits again. */
521 if (GET_CODE (PATTERN (insn)) == SEQUENCE
522 && INSN_ANNULLED_BRANCH_P (this_jump_insn))
524 for (i = 1; i < XVECLEN (PATTERN (insn), 0); i++)
525 INSN_FROM_TARGET_P (XVECEXP (PATTERN (insn), 0, i))
526 = ! INSN_FROM_TARGET_P (XVECEXP (PATTERN (insn), 0, i));
529 mark_set_resources (insn, &target_set, 0,
532 for (i = 1; i < XVECLEN (PATTERN (insn), 0); i++)
533 INSN_FROM_TARGET_P (XVECEXP (PATTERN (insn), 0, i))
534 = ! INSN_FROM_TARGET_P (XVECEXP (PATTERN (insn), 0, i));
536 mark_set_resources (insn, &set, 0, MARK_SRC_DEST_CALL);
540 mark_set_resources (insn, &set, 0, MARK_SRC_DEST_CALL);
545 COPY_HARD_REG_SET (scratch, target_set.regs);
546 AND_COMPL_HARD_REG_SET (scratch, needed.regs);
547 AND_COMPL_HARD_REG_SET (target_res.regs, scratch);
549 fallthrough_res = *res;
550 COPY_HARD_REG_SET (scratch, set.regs);
551 AND_COMPL_HARD_REG_SET (scratch, needed.regs);
552 AND_COMPL_HARD_REG_SET (fallthrough_res.regs, scratch);
554 find_dead_or_set_registers (JUMP_LABEL (this_jump_insn),
555 &target_res, 0, jump_count,
557 find_dead_or_set_registers (next,
558 &fallthrough_res, 0, jump_count,
560 IOR_HARD_REG_SET (fallthrough_res.regs, target_res.regs);
561 AND_HARD_REG_SET (res->regs, fallthrough_res.regs);
569 /* Don't try this optimization if we expired our jump count
570 above, since that would mean there may be an infinite loop
571 in the function being compiled. */
577 mark_referenced_resources (insn, &needed, 1);
578 mark_set_resources (insn, &set, 0, MARK_SRC_DEST_CALL);
580 COPY_HARD_REG_SET (scratch, set.regs);
581 AND_COMPL_HARD_REG_SET (scratch, needed.regs);
582 AND_COMPL_HARD_REG_SET (res->regs, scratch);
588 /* Given X, a part of an insn, and a pointer to a `struct resource',
589 RES, indicate which resources are modified by the insn. If
590 MARK_TYPE is MARK_SRC_DEST_CALL, also mark resources potentially
591 set by the called routine. If MARK_TYPE is MARK_DEST, only mark SET_DESTs
593 If IN_DEST is nonzero, it means we are inside a SET. Otherwise,
594 objects are being referenced instead of set.
596 We never mark the insn as modifying the condition code unless it explicitly
597 SETs CC0 even though this is not totally correct. The reason for this is
598 that we require a SET of CC0 to immediately precede the reference to CC0.
599 So if some other insn sets CC0 as a side-effect, we know it cannot affect
600 our computation and thus may be placed in a delay slot. */
603 mark_set_resources (x, res, in_dest, mark_type)
605 register struct resources *res;
607 enum mark_resource_type mark_type;
612 const char *format_ptr;
630 /* These don't set any resources. */
639 /* Called routine modifies the condition code, memory, any registers
640 that aren't saved across calls, global registers and anything
641 explicitly CLOBBERed immediately after the CALL_INSN. */
643 if (mark_type == MARK_SRC_DEST_CALL)
645 rtx next = NEXT_INSN (x);
646 rtx prev = PREV_INSN (x);
649 res->cc = res->memory = 1;
650 for (r = 0; r < FIRST_PSEUDO_REGISTER; r++)
651 if (call_used_regs[r] || global_regs[r])
652 SET_HARD_REG_BIT (res->regs, r);
654 /* If X is part of a delay slot sequence, then NEXT should be
655 the first insn after the sequence. */
656 if (NEXT_INSN (prev) != x)
657 next = NEXT_INSN (NEXT_INSN (prev));
659 for (link = CALL_INSN_FUNCTION_USAGE (x);
660 link; link = XEXP (link, 1))
661 if (GET_CODE (XEXP (link, 0)) == CLOBBER)
662 mark_set_resources (SET_DEST (XEXP (link, 0)), res, 1,
665 /* Check for a NOTE_INSN_SETJMP. If it exists, then we must
666 assume that this call can clobber any register. */
667 if (next && GET_CODE (next) == NOTE
668 && NOTE_LINE_NUMBER (next) == NOTE_INSN_SETJMP)
669 SET_HARD_REG_SET (res->regs);
672 /* ... and also what its RTL says it modifies, if anything. */
677 /* An insn consisting of just a CLOBBER (or USE) is just for flow
678 and doesn't actually do anything, so we ignore it. */
680 #ifdef INSN_SETS_ARE_DELAYED
681 if (mark_type != MARK_SRC_DEST_CALL
682 && INSN_SETS_ARE_DELAYED (x))
687 if (GET_CODE (x) != USE && GET_CODE (x) != CLOBBER)
692 /* If the source of a SET is a CALL, this is actually done by
693 the called routine. So only include it if we are to include the
694 effects of the calling routine. */
696 mark_set_resources (SET_DEST (x), res,
697 (mark_type == MARK_SRC_DEST_CALL
698 || GET_CODE (SET_SRC (x)) != CALL),
701 if (mark_type != MARK_DEST)
702 mark_set_resources (SET_SRC (x), res, 0, MARK_SRC_DEST);
706 mark_set_resources (XEXP (x, 0), res, 1, MARK_SRC_DEST);
710 for (i = 0; i < XVECLEN (x, 0); i++)
711 if (! (INSN_ANNULLED_BRANCH_P (XVECEXP (x, 0, 0))
712 && INSN_FROM_TARGET_P (XVECEXP (x, 0, i))))
713 mark_set_resources (XVECEXP (x, 0, i), res, 0, mark_type);
720 mark_set_resources (XEXP (x, 0), res, 1, MARK_SRC_DEST);
725 if (! (mark_type == MARK_DEST && in_dest))
727 mark_set_resources (XEXP (x, 0), res, in_dest, MARK_SRC_DEST);
728 mark_set_resources (XEXP (x, 1), res, 0, MARK_SRC_DEST);
729 mark_set_resources (XEXP (x, 2), res, 0, MARK_SRC_DEST);
737 res->unch_memory |= RTX_UNCHANGING_P (x);
738 res->volatil |= MEM_VOLATILE_P (x);
741 mark_set_resources (XEXP (x, 0), res, 0, MARK_SRC_DEST);
747 if (GET_CODE (SUBREG_REG (x)) != REG)
748 mark_set_resources (SUBREG_REG (x), res, in_dest, mark_type);
751 unsigned int regno = REGNO (SUBREG_REG (x)) + SUBREG_WORD (x);
752 unsigned int last_regno
753 = regno + HARD_REGNO_NREGS (regno, GET_MODE (x));
755 for (r = regno; r < last_regno; r++)
756 SET_HARD_REG_BIT (res->regs, r);
763 for (r = 0; r < HARD_REGNO_NREGS (REGNO (x), GET_MODE (x)); r++)
764 SET_HARD_REG_BIT (res->regs, REGNO (x) + r);
767 case STRICT_LOW_PART:
768 if (! (mark_type == MARK_DEST && in_dest))
770 mark_set_resources (XEXP (x, 0), res, 0, MARK_SRC_DEST);
774 case UNSPEC_VOLATILE:
776 /* Traditional asm's are always volatile. */
785 res->volatil |= MEM_VOLATILE_P (x);
787 /* For all ASM_OPERANDS, we must traverse the vector of input operands.
788 We can not just fall through here since then we would be confused
789 by the ASM_INPUT rtx inside ASM_OPERANDS, which do not indicate
790 traditional asms unlike their normal usage. */
792 for (i = 0; i < ASM_OPERANDS_INPUT_LENGTH (x); i++)
793 mark_set_resources (ASM_OPERANDS_INPUT (x, i), res, in_dest,
801 /* Process each sub-expression and flag what it needs. */
802 format_ptr = GET_RTX_FORMAT (code);
803 for (i = 0; i < GET_RTX_LENGTH (code); i++)
804 switch (*format_ptr++)
807 mark_set_resources (XEXP (x, i), res, in_dest, mark_type);
811 for (j = 0; j < XVECLEN (x, i); j++)
812 mark_set_resources (XVECEXP (x, i, j), res, in_dest, mark_type);
817 /* Set the resources that are live at TARGET.
819 If TARGET is zero, we refer to the end of the current function and can
820 return our precomputed value.
822 Otherwise, we try to find out what is live by consulting the basic block
823 information. This is tricky, because we must consider the actions of
824 reload and jump optimization, which occur after the basic block information
827 Accordingly, we proceed as follows::
829 We find the previous BARRIER and look at all immediately following labels
830 (with no intervening active insns) to see if any of them start a basic
831 block. If we hit the start of the function first, we use block 0.
833 Once we have found a basic block and a corresponding first insns, we can
834 accurately compute the live status from basic_block_live_regs and
835 reg_renumber. (By starting at a label following a BARRIER, we are immune
836 to actions taken by reload and jump.) Then we scan all insns between
837 that point and our target. For each CLOBBER (or for call-clobbered regs
838 when we pass a CALL_INSN), mark the appropriate registers are dead. For
839 a SET, mark them as live.
841 We have to be careful when using REG_DEAD notes because they are not
842 updated by such things as find_equiv_reg. So keep track of registers
843 marked as dead that haven't been assigned to, and mark them dead at the
844 next CODE_LABEL since reload and jump won't propagate values across labels.
846 If we cannot find the start of a basic block (should be a very rare
847 case, if it can happen at all), mark everything as potentially live.
849 Next, scan forward from TARGET looking for things set or clobbered
850 before they are used. These are not live.
852 Because we can be called many times on the same target, save our results
853 in a hash table indexed by INSN_UID. This is only done if the function
854 init_resource_info () was invoked before we are called. */
857 mark_target_live_regs (insns, target, res)
860 struct resources *res;
864 struct target_info *tinfo = NULL;
868 HARD_REG_SET scratch;
869 struct resources set, needed;
871 /* Handle end of function. */
874 *res = end_of_function_needs;
878 /* We have to assume memory is needed, but the CC isn't. */
880 res->volatil = res->unch_memory = 0;
883 /* See if we have computed this value already. */
884 if (target_hash_table != NULL)
886 for (tinfo = target_hash_table[INSN_UID (target) % TARGET_HASH_PRIME];
887 tinfo; tinfo = tinfo->next)
888 if (tinfo->uid == INSN_UID (target))
891 /* Start by getting the basic block number. If we have saved
892 information, we can get it from there unless the insn at the
893 start of the basic block has been deleted. */
894 if (tinfo && tinfo->block != -1
895 && ! INSN_DELETED_P (BLOCK_HEAD (tinfo->block)))
900 b = find_basic_block (target);
902 if (target_hash_table != NULL)
906 /* If the information is up-to-date, use it. Otherwise, we will
908 if (b == tinfo->block && b != -1 && tinfo->bb_tick == bb_ticks[b])
910 COPY_HARD_REG_SET (res->regs, tinfo->live_regs);
916 /* Allocate a place to put our results and chain it into the
918 tinfo = (struct target_info *) oballoc (sizeof (struct target_info));
919 tinfo->uid = INSN_UID (target);
921 tinfo->next = target_hash_table[INSN_UID (target) % TARGET_HASH_PRIME];
922 target_hash_table[INSN_UID (target) % TARGET_HASH_PRIME] = tinfo;
926 CLEAR_HARD_REG_SET (pending_dead_regs);
928 /* If we found a basic block, get the live registers from it and update
929 them with anything set or killed between its start and the insn before
930 TARGET. Otherwise, we must assume everything is live. */
933 regset regs_live = BASIC_BLOCK (b)->global_live_at_start;
936 rtx start_insn, stop_insn;
938 /* Compute hard regs live at start of block -- this is the real hard regs
939 marked live, plus live pseudo regs that have been renumbered to
942 REG_SET_TO_HARD_REG_SET (current_live_regs, regs_live);
944 EXECUTE_IF_SET_IN_REG_SET
945 (regs_live, FIRST_PSEUDO_REGISTER, i,
947 if (reg_renumber[i] >= 0)
949 regno = reg_renumber[i];
951 j < regno + HARD_REGNO_NREGS (regno,
952 PSEUDO_REGNO_MODE (i));
954 SET_HARD_REG_BIT (current_live_regs, j);
958 /* Get starting and ending insn, handling the case where each might
960 start_insn = (b == 0 ? insns : BLOCK_HEAD (b));
963 if (GET_CODE (start_insn) == INSN
964 && GET_CODE (PATTERN (start_insn)) == SEQUENCE)
965 start_insn = XVECEXP (PATTERN (start_insn), 0, 0);
967 if (GET_CODE (stop_insn) == INSN
968 && GET_CODE (PATTERN (stop_insn)) == SEQUENCE)
969 stop_insn = next_insn (PREV_INSN (stop_insn));
971 for (insn = start_insn; insn != stop_insn;
972 insn = next_insn_no_annul (insn))
975 rtx real_insn = insn;
977 /* If this insn is from the target of a branch, it isn't going to
978 be used in the sequel. If it is used in both cases, this
979 test will not be true. */
980 if (INSN_FROM_TARGET_P (insn))
983 /* If this insn is a USE made by update_block, we care about the
985 if (GET_CODE (insn) == INSN && GET_CODE (PATTERN (insn)) == USE
986 && GET_RTX_CLASS (GET_CODE (XEXP (PATTERN (insn), 0))) == 'i')
987 real_insn = XEXP (PATTERN (insn), 0);
989 if (GET_CODE (real_insn) == CALL_INSN)
991 /* CALL clobbers all call-used regs that aren't fixed except
992 sp, ap, and fp. Do this before setting the result of the
994 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
995 if (call_used_regs[i]
996 && i != STACK_POINTER_REGNUM && i != FRAME_POINTER_REGNUM
997 && i != ARG_POINTER_REGNUM
998 #if HARD_FRAME_POINTER_REGNUM != FRAME_POINTER_REGNUM
999 && i != HARD_FRAME_POINTER_REGNUM
1001 #if ARG_POINTER_REGNUM != FRAME_POINTER_REGNUM
1002 && ! (i == ARG_POINTER_REGNUM && fixed_regs[i])
1004 #if defined (PIC_OFFSET_TABLE_REGNUM) && !defined (PIC_OFFSET_TABLE_REG_CALL_CLOBBERED)
1005 && ! (i == PIC_OFFSET_TABLE_REGNUM && flag_pic)
1008 CLEAR_HARD_REG_BIT (current_live_regs, i);
1010 /* A CALL_INSN sets any global register live, since it may
1011 have been modified by the call. */
1012 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
1014 SET_HARD_REG_BIT (current_live_regs, i);
1017 /* Mark anything killed in an insn to be deadened at the next
1018 label. Ignore USE insns; the only REG_DEAD notes will be for
1019 parameters. But they might be early. A CALL_INSN will usually
1020 clobber registers used for parameters. It isn't worth bothering
1021 with the unlikely case when it won't. */
1022 if ((GET_CODE (real_insn) == INSN
1023 && GET_CODE (PATTERN (real_insn)) != USE
1024 && GET_CODE (PATTERN (real_insn)) != CLOBBER)
1025 || GET_CODE (real_insn) == JUMP_INSN
1026 || GET_CODE (real_insn) == CALL_INSN)
1028 for (link = REG_NOTES (real_insn); link; link = XEXP (link, 1))
1029 if (REG_NOTE_KIND (link) == REG_DEAD
1030 && GET_CODE (XEXP (link, 0)) == REG
1031 && REGNO (XEXP (link, 0)) < FIRST_PSEUDO_REGISTER)
1033 int first_regno = REGNO (XEXP (link, 0));
1036 + HARD_REGNO_NREGS (first_regno,
1037 GET_MODE (XEXP (link, 0))));
1039 for (i = first_regno; i < last_regno; i++)
1040 SET_HARD_REG_BIT (pending_dead_regs, i);
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 && GET_CODE (XEXP (link, 0)) == REG
1050 && REGNO (XEXP (link, 0)) < FIRST_PSEUDO_REGISTER)
1052 int first_regno = REGNO (XEXP (link, 0));
1055 + HARD_REGNO_NREGS (first_regno,
1056 GET_MODE (XEXP (link, 0))));
1058 for (i = first_regno; i < last_regno; i++)
1059 CLEAR_HARD_REG_BIT (current_live_regs, i);
1063 else if (GET_CODE (real_insn) == CODE_LABEL)
1065 /* A label clobbers the pending dead registers since neither
1066 reload nor jump will propagate a value across a label. */
1067 AND_COMPL_HARD_REG_SET (current_live_regs, pending_dead_regs);
1068 CLEAR_HARD_REG_SET (pending_dead_regs);
1071 /* The beginning of the epilogue corresponds to the end of the
1072 RTL chain when there are no epilogue insns. Certain resources
1073 are implicitly required at that point. */
1074 else if (GET_CODE (real_insn) == NOTE
1075 && NOTE_LINE_NUMBER (real_insn) == NOTE_INSN_EPILOGUE_BEG)
1076 IOR_HARD_REG_SET (current_live_regs, start_of_epilogue_needs.regs);
1079 COPY_HARD_REG_SET (res->regs, current_live_regs);
1083 tinfo->bb_tick = bb_ticks[b];
1087 /* We didn't find the start of a basic block. Assume everything
1088 in use. This should happen only extremely rarely. */
1089 SET_HARD_REG_SET (res->regs);
1091 CLEAR_RESOURCE (&set);
1092 CLEAR_RESOURCE (&needed);
1094 jump_insn = find_dead_or_set_registers (target, res, &jump_target, 0,
1097 /* If we hit an unconditional branch, we have another way of finding out
1098 what is live: we can see what is live at the branch target and include
1099 anything used but not set before the branch. We add the live
1100 resources found using the test below to those found until now. */
1104 struct resources new_resources;
1105 rtx stop_insn = next_active_insn (jump_insn);
1107 mark_target_live_regs (insns, next_active_insn (jump_target),
1109 CLEAR_RESOURCE (&set);
1110 CLEAR_RESOURCE (&needed);
1112 /* Include JUMP_INSN in the needed registers. */
1113 for (insn = target; insn != stop_insn; insn = next_active_insn (insn))
1115 mark_referenced_resources (insn, &needed, 1);
1117 COPY_HARD_REG_SET (scratch, needed.regs);
1118 AND_COMPL_HARD_REG_SET (scratch, set.regs);
1119 IOR_HARD_REG_SET (new_resources.regs, scratch);
1121 mark_set_resources (insn, &set, 0, MARK_SRC_DEST_CALL);
1124 IOR_HARD_REG_SET (res->regs, new_resources.regs);
1129 COPY_HARD_REG_SET (tinfo->live_regs, res->regs);
1133 /* Initialize the resources required by mark_target_live_regs ().
1134 This should be invoked before the first call to mark_target_live_regs. */
1137 init_resource_info (epilogue_insn)
1142 /* Indicate what resources are required to be valid at the end of the current
1143 function. The condition code never is and memory always is. If the
1144 frame pointer is needed, it is and so is the stack pointer unless
1145 EXIT_IGNORE_STACK is non-zero. If the frame pointer is not needed, the
1146 stack pointer is. Registers used to return the function value are
1147 needed. Registers holding global variables are needed. */
1149 end_of_function_needs.cc = 0;
1150 end_of_function_needs.memory = 1;
1151 end_of_function_needs.unch_memory = 0;
1152 CLEAR_HARD_REG_SET (end_of_function_needs.regs);
1154 if (frame_pointer_needed)
1156 SET_HARD_REG_BIT (end_of_function_needs.regs, FRAME_POINTER_REGNUM);
1157 #if HARD_FRAME_POINTER_REGNUM != FRAME_POINTER_REGNUM
1158 SET_HARD_REG_BIT (end_of_function_needs.regs, HARD_FRAME_POINTER_REGNUM);
1160 #ifdef EXIT_IGNORE_STACK
1161 if (! EXIT_IGNORE_STACK
1162 || current_function_sp_is_unchanging)
1164 SET_HARD_REG_BIT (end_of_function_needs.regs, STACK_POINTER_REGNUM);
1167 SET_HARD_REG_BIT (end_of_function_needs.regs, STACK_POINTER_REGNUM);
1169 if (current_function_return_rtx != 0)
1170 mark_referenced_resources (current_function_return_rtx,
1171 &end_of_function_needs, 1);
1173 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
1175 #ifdef EPILOGUE_USES
1176 || EPILOGUE_USES (i)
1179 SET_HARD_REG_BIT (end_of_function_needs.regs, i);
1181 /* The registers required to be live at the end of the function are
1182 represented in the flow information as being dead just prior to
1183 reaching the end of the function. For example, the return of a value
1184 might be represented by a USE of the return register immediately
1185 followed by an unconditional jump to the return label where the
1186 return label is the end of the RTL chain. The end of the RTL chain
1187 is then taken to mean that the return register is live.
1189 This sequence is no longer maintained when epilogue instructions are
1190 added to the RTL chain. To reconstruct the original meaning, the
1191 start of the epilogue (NOTE_INSN_EPILOGUE_BEG) is regarded as the
1192 point where these registers become live (start_of_epilogue_needs).
1193 If epilogue instructions are present, the registers set by those
1194 instructions won't have been processed by flow. Thus, those
1195 registers are additionally required at the end of the RTL chain
1196 (end_of_function_needs). */
1198 start_of_epilogue_needs = end_of_function_needs;
1200 while ((epilogue_insn = next_nonnote_insn (epilogue_insn)))
1201 mark_set_resources (epilogue_insn, &end_of_function_needs, 0,
1202 MARK_SRC_DEST_CALL);
1204 /* Allocate and initialize the tables used by mark_target_live_regs. */
1205 target_hash_table = (struct target_info **)
1206 xcalloc (TARGET_HASH_PRIME, sizeof (struct target_info *));
1207 bb_ticks = (int *) xcalloc (n_basic_blocks, sizeof (int));
1210 /* Free up the resources allcated to mark_target_live_regs (). This
1211 should be invoked after the last call to mark_target_live_regs (). */
1214 free_resource_info ()
1216 if (target_hash_table != NULL)
1218 free (target_hash_table);
1219 target_hash_table = NULL;
1222 if (bb_ticks != NULL)
1229 /* Clear any hashed information that we have stored for INSN. */
1232 clear_hashed_info_for_insn (insn)
1235 struct target_info *tinfo;
1237 if (target_hash_table != NULL)
1239 for (tinfo = target_hash_table[INSN_UID (insn) % TARGET_HASH_PRIME];
1240 tinfo; tinfo = tinfo->next)
1241 if (tinfo->uid == INSN_UID (insn))
1249 /* Increment the tick count for the basic block that contains INSN. */
1252 incr_ticks_for_insn (insn)
1255 int b = find_basic_block (insn);
1261 /* Add TRIAL to the set of resources used at the end of the current
1264 mark_end_of_function_resources (trial, include_delayed_effects)
1266 int include_delayed_effects;
1268 mark_referenced_resources (trial, &end_of_function_needs,
1269 include_delayed_effects);
1272 /* Try to find a hard register of mode MODE, matching the register class in
1273 CLASS_STR, which is available at the beginning of insn CURRENT_INSN and
1274 remains available until the end of LAST_INSN. LAST_INSN may be NULL_RTX,
1275 in which case the only condition is that the register must be available
1276 before CURRENT_INSN.
1277 Registers that already have bits set in REG_SET will not be considered.
1279 If an appropriate register is available, it will be returned and the
1280 corresponding bit(s) in REG_SET will be set; otherwise, NULL_RTX is
1284 find_free_register (current_insn, last_insn, class_str, mode, reg_set)
1285 rtx current_insn, last_insn;
1286 const char *class_str;
1288 HARD_REG_SET *reg_set;
1291 struct resources used;
1292 unsigned char clet = class_str[0];
1293 enum reg_class class
1294 = (clet == 'r' ? GENERAL_REGS : REG_CLASS_FROM_LETTER (clet));
1296 mark_target_live_regs (get_insns (), current_insn, &used);
1298 while (current_insn != last_insn)
1300 /* Exclude anything set in this insn. */
1301 mark_set_resources (PATTERN (current_insn), &used, 0,
1302 MARK_SRC_DEST_CALL);
1303 current_insn = next_nonnote_insn (current_insn);
1307 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
1312 #ifdef REG_ALLOC_ORDER
1313 regno = reg_alloc_order [i];
1318 /* Don't allocate fixed registers. */
1319 if (fixed_regs[regno])
1321 /* Make sure the register is of the right class. */
1322 if (! TEST_HARD_REG_BIT (reg_class_contents[class], regno))
1324 /* And can support the mode we need. */
1325 if (! HARD_REGNO_MODE_OK (regno, mode))
1327 /* And that we don't create an extra save/restore. */
1328 if (! call_used_regs[regno] && ! regs_ever_live[regno])
1330 /* And we don't clobber traceback for noreturn functions. */
1331 if ((regno == FRAME_POINTER_REGNUM || regno == HARD_FRAME_POINTER_REGNUM)
1332 && (! reload_completed || frame_pointer_needed))
1336 for (j = HARD_REGNO_NREGS (regno, mode) - 1; j >= 0; j--)
1338 if (TEST_HARD_REG_BIT (*reg_set, regno + j)
1339 || TEST_HARD_REG_BIT (used.regs, regno + j))
1347 for (j = HARD_REGNO_NREGS (regno, mode) - 1; j >= 0; j--)
1349 SET_HARD_REG_BIT (*reg_set, regno + j);
1351 return gen_rtx_REG (mode, regno);
1357 /* Return true if REG is dead at CURRENT_INSN. */
1360 reg_dead_p (current_insn, reg)
1361 rtx current_insn, reg;
1363 struct resources used;
1366 mark_target_live_regs (get_insns (), current_insn, &used);
1368 regno = REGNO (reg);
1369 for (j = HARD_REGNO_NREGS (regno, GET_MODE (reg)) - 1; j >= 0; j--)
1371 if (TEST_HARD_REG_BIT (used.regs, regno + j))