1 /* Definitions for computing resource usage of specific insns.
2 Copyright (C) 1999-2016 Free Software Foundation, Inc.
4 This file is part of GCC.
6 GCC is free software; you can redistribute it and/or modify it under
7 the terms of the GNU General Public License as published by the Free
8 Software Foundation; either version 3, or (at your option) any later
11 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
12 WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
16 You should have received a copy of the GNU General Public License
17 along with GCC; see the file COPYING3. If not see
18 <http://www.gnu.org/licenses/>. */
22 #include "coretypes.h"
30 #include "insn-attr.h"
33 /* This structure is used to record liveness information at the targets or
34 fallthrough insns of branches. We will most likely need the information
35 at targets again, so save them in a hash table rather than recomputing them
40 int uid; /* INSN_UID of target. */
41 struct target_info *next; /* Next info for same hash bucket. */
42 HARD_REG_SET live_regs; /* Registers live at target. */
43 int block; /* Basic block number containing target. */
44 int bb_tick; /* Generation count of basic block info. */
47 #define TARGET_HASH_PRIME 257
49 /* Indicates what resources are required at the beginning of the epilogue. */
50 static struct resources start_of_epilogue_needs;
52 /* Indicates what resources are required at function end. */
53 static struct resources end_of_function_needs;
55 /* Define the hash table itself. */
56 static struct target_info **target_hash_table = NULL;
58 /* For each basic block, we maintain a generation number of its basic
59 block info, which is updated each time we move an insn from the
60 target of a jump. This is the generation number indexed by block
65 /* Marks registers possibly live at the current place being scanned by
66 mark_target_live_regs. Also used by update_live_status. */
68 static HARD_REG_SET current_live_regs;
70 /* Marks registers for which we have seen a REG_DEAD note but no assignment.
71 Also only used by the next two functions. */
73 static HARD_REG_SET pending_dead_regs;
75 static void update_live_status (rtx, const_rtx, void *);
76 static int find_basic_block (rtx_insn *, int);
77 static rtx_insn *next_insn_no_annul (rtx_insn *);
78 static rtx_insn *find_dead_or_set_registers (rtx_insn *, struct resources*,
79 rtx *, int, struct resources,
82 /* Utility function called from mark_target_live_regs via note_stores.
83 It deadens any CLOBBERed registers and livens any SET registers. */
86 update_live_status (rtx dest, const_rtx x, void *data ATTRIBUTE_UNUSED)
88 int first_regno, last_regno;
92 && (GET_CODE (dest) != SUBREG || !REG_P (SUBREG_REG (dest))))
95 if (GET_CODE (dest) == SUBREG)
97 first_regno = subreg_regno (dest);
98 last_regno = first_regno + subreg_nregs (dest);
103 first_regno = REGNO (dest);
104 last_regno = END_REGNO (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);
118 /* Find the number of the basic block with correct live register
119 information that starts closest to INSN. Return -1 if we couldn't
120 find such a basic block or the beginning is more than
121 SEARCH_LIMIT instructions before INSN. Use SEARCH_LIMIT = -1 for
124 The delay slot filling code destroys the control-flow graph so,
125 instead of finding the basic block containing INSN, we search
126 backwards toward a BARRIER where the live register information is
130 find_basic_block (rtx_insn *insn, int search_limit)
132 /* Scan backwards to the previous BARRIER. Then see if we can find a
133 label that starts a basic block. Return the basic block number. */
134 for (insn = prev_nonnote_insn (insn);
135 insn && !BARRIER_P (insn) && search_limit != 0;
136 insn = prev_nonnote_insn (insn), --search_limit)
139 /* The closest BARRIER is too far away. */
140 if (search_limit == 0)
143 /* The start of the function. */
145 return ENTRY_BLOCK_PTR_FOR_FN (cfun)->next_bb->index;
147 /* See if any of the upcoming CODE_LABELs start a basic block. If we reach
148 anything other than a CODE_LABEL or note, we can't find this code. */
149 for (insn = next_nonnote_insn (insn);
150 insn && LABEL_P (insn);
151 insn = next_nonnote_insn (insn))
152 if (BLOCK_FOR_INSN (insn))
153 return BLOCK_FOR_INSN (insn)->index;
158 /* Similar to next_insn, but ignores insns in the delay slots of
159 an annulled branch. */
162 next_insn_no_annul (rtx_insn *insn)
166 /* If INSN is an annulled branch, skip any insns from the target
169 && INSN_ANNULLED_BRANCH_P (insn)
170 && NEXT_INSN (PREV_INSN (insn)) != insn)
172 rtx_insn *next = NEXT_INSN (insn);
174 while ((NONJUMP_INSN_P (next) || JUMP_P (next) || CALL_P (next))
175 && INSN_FROM_TARGET_P (next))
178 next = NEXT_INSN (insn);
182 insn = NEXT_INSN (insn);
183 if (insn && NONJUMP_INSN_P (insn)
184 && GET_CODE (PATTERN (insn)) == SEQUENCE)
185 insn = as_a <rtx_sequence *> (PATTERN (insn))->insn (0);
191 /* Given X, some rtl, and RES, a pointer to a `struct resource', mark
192 which resources are referenced by the insn. If INCLUDE_DELAYED_EFFECTS
193 is TRUE, resources used by the called routine will be included for
197 mark_referenced_resources (rtx x, struct resources *res,
198 bool include_delayed_effects)
200 enum rtx_code code = GET_CODE (x);
203 const char *format_ptr;
205 /* Handle leaf items for which we set resource flags. Also, special-case
206 CALL, SET and CLOBBER operators. */
217 if (!REG_P (SUBREG_REG (x)))
218 mark_referenced_resources (SUBREG_REG (x), res, false);
221 unsigned int regno = subreg_regno (x);
222 unsigned int last_regno = regno + subreg_nregs (x);
224 gcc_assert (last_regno <= FIRST_PSEUDO_REGISTER);
225 for (r = regno; r < last_regno; r++)
226 SET_HARD_REG_BIT (res->regs, r);
231 gcc_assert (HARD_REGISTER_P (x));
232 add_to_hard_reg_set (&res->regs, GET_MODE (x), REGNO (x));
236 /* If this memory shouldn't change, it really isn't referencing
238 if (! MEM_READONLY_P (x))
240 res->volatil |= MEM_VOLATILE_P (x);
242 /* Mark registers used to access memory. */
243 mark_referenced_resources (XEXP (x, 0), res, false);
250 case UNSPEC_VOLATILE:
253 /* Traditional asm's are always volatile. */
258 res->volatil |= MEM_VOLATILE_P (x);
260 /* For all ASM_OPERANDS, we must traverse the vector of input operands.
261 We can not just fall through here since then we would be confused
262 by the ASM_INPUT rtx inside ASM_OPERANDS, which do not indicate
263 traditional asms unlike their normal usage. */
265 for (i = 0; i < ASM_OPERANDS_INPUT_LENGTH (x); i++)
266 mark_referenced_resources (ASM_OPERANDS_INPUT (x, i), res, false);
270 /* The first operand will be a (MEM (xxx)) but doesn't really reference
271 memory. The second operand may be referenced, though. */
272 mark_referenced_resources (XEXP (XEXP (x, 0), 0), res, false);
273 mark_referenced_resources (XEXP (x, 1), res, false);
277 /* Usually, the first operand of SET is set, not referenced. But
278 registers used to access memory are referenced. SET_DEST is
279 also referenced if it is a ZERO_EXTRACT. */
281 mark_referenced_resources (SET_SRC (x), res, false);
284 if (GET_CODE (x) == ZERO_EXTRACT
285 || GET_CODE (x) == STRICT_LOW_PART)
286 mark_referenced_resources (x, res, false);
287 else if (GET_CODE (x) == SUBREG)
290 mark_referenced_resources (XEXP (x, 0), res, false);
297 if (include_delayed_effects)
299 /* A CALL references memory, the frame pointer if it exists, the
300 stack pointer, any global registers and any registers given in
301 USE insns immediately in front of the CALL.
303 However, we may have moved some of the parameter loading insns
304 into the delay slot of this CALL. If so, the USE's for them
305 don't count and should be skipped. */
306 rtx_insn *insn = PREV_INSN (as_a <rtx_insn *> (x));
307 rtx_sequence *sequence = 0;
311 /* If we are part of a delay slot sequence, point at the SEQUENCE. */
312 if (NEXT_INSN (insn) != x)
314 sequence = as_a <rtx_sequence *> (PATTERN (NEXT_INSN (insn)));
315 seq_size = sequence->len ();
316 gcc_assert (GET_CODE (sequence) == SEQUENCE);
320 SET_HARD_REG_BIT (res->regs, STACK_POINTER_REGNUM);
321 if (frame_pointer_needed)
323 SET_HARD_REG_BIT (res->regs, FRAME_POINTER_REGNUM);
324 if (!HARD_FRAME_POINTER_IS_FRAME_POINTER)
325 SET_HARD_REG_BIT (res->regs, HARD_FRAME_POINTER_REGNUM);
328 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
330 SET_HARD_REG_BIT (res->regs, i);
332 /* Check for a REG_SETJMP. If it exists, then we must
333 assume that this call can need any register.
335 This is done to be more conservative about how we handle setjmp.
336 We assume that they both use and set all registers. Using all
337 registers ensures that a register will not be considered dead
338 just because it crosses a setjmp call. A register should be
339 considered dead only if the setjmp call returns nonzero. */
340 if (find_reg_note (x, REG_SETJMP, NULL))
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 (sequence->element (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 if (GET_CODE (PATTERN (x)) == COND_EXEC)
372 /* In addition to the usual references, also consider all outputs
373 as referenced, to compensate for mark_set_resources treating
374 them as killed. This is similar to ZERO_EXTRACT / STRICT_LOW_PART
375 handling, execpt that we got a partial incidence instead of a partial
377 mark_set_resources (x, res, 0,
378 include_delayed_effects
379 ? MARK_SRC_DEST_CALL : MARK_SRC_DEST);
381 if (! include_delayed_effects
382 && INSN_REFERENCES_ARE_DELAYED (as_a <rtx_insn *> (x)))
385 /* No special processing, just speed up. */
386 mark_referenced_resources (PATTERN (x), res, include_delayed_effects);
393 /* Process each sub-expression and flag what it needs. */
394 format_ptr = GET_RTX_FORMAT (code);
395 for (i = 0; i < GET_RTX_LENGTH (code); i++)
396 switch (*format_ptr++)
399 mark_referenced_resources (XEXP (x, i), res, include_delayed_effects);
403 for (j = 0; j < XVECLEN (x, i); j++)
404 mark_referenced_resources (XVECEXP (x, i, j), res,
405 include_delayed_effects);
410 /* A subroutine of mark_target_live_regs. Search forward from TARGET
411 looking for registers that are set before they are used. These are dead.
412 Stop after passing a few conditional jumps, and/or a small
413 number of unconditional branches. */
416 find_dead_or_set_registers (rtx_insn *target, struct resources *res,
417 rtx *jump_target, int jump_count,
418 struct resources set, struct resources needed)
420 HARD_REG_SET scratch;
423 rtx_insn *jump_insn = 0;
426 for (insn = target; insn; insn = next_insn)
428 rtx_insn *this_insn = insn;
430 next_insn = NEXT_INSN (insn);
432 /* If this instruction can throw an exception, then we don't
433 know where we might end up next. That means that we have to
434 assume that whatever we have already marked as live really is
436 if (can_throw_internal (insn))
439 switch (GET_CODE (insn))
442 /* After a label, any pending dead registers that weren't yet
443 used can be made dead. */
444 AND_COMPL_HARD_REG_SET (pending_dead_regs, needed.regs);
445 AND_COMPL_HARD_REG_SET (res->regs, pending_dead_regs);
446 CLEAR_HARD_REG_SET (pending_dead_regs);
455 if (GET_CODE (PATTERN (insn)) == USE)
457 /* If INSN is a USE made by update_block, we care about the
458 underlying insn. Any registers set by the underlying insn
459 are live since the insn is being done somewhere else. */
460 if (INSN_P (XEXP (PATTERN (insn), 0)))
461 mark_set_resources (XEXP (PATTERN (insn), 0), res, 0,
464 /* All other USE insns are to be ignored. */
467 else if (GET_CODE (PATTERN (insn)) == CLOBBER)
469 else if (rtx_sequence *seq =
470 dyn_cast <rtx_sequence *> (PATTERN (insn)))
472 /* An unconditional jump can be used to fill the delay slot
473 of a call, so search for a JUMP_INSN in any position. */
474 for (i = 0; i < seq->len (); i++)
476 this_insn = seq->insn (i);
477 if (JUMP_P (this_insn))
486 if (rtx_jump_insn *this_jump_insn =
487 dyn_cast <rtx_jump_insn *> (this_insn))
489 if (jump_count++ < 10)
491 if (any_uncondjump_p (this_jump_insn)
492 || ANY_RETURN_P (PATTERN (this_jump_insn)))
494 rtx lab_or_return = this_jump_insn->jump_label ();
495 if (ANY_RETURN_P (lab_or_return))
498 next_insn = as_a <rtx_insn *> (lab_or_return);
503 *jump_target = JUMP_LABEL (this_jump_insn);
506 else if (any_condjump_p (this_jump_insn))
508 struct resources target_set, target_res;
509 struct resources fallthrough_res;
511 /* We can handle conditional branches here by following
512 both paths, and then IOR the results of the two paths
513 together, which will give us registers that are dead
514 on both paths. Since this is expensive, we give it
515 a much higher cost than unconditional branches. The
516 cost was chosen so that we will follow at most 1
517 conditional branch. */
520 if (jump_count >= 10)
523 mark_referenced_resources (insn, &needed, true);
525 /* For an annulled branch, mark_set_resources ignores slots
526 filled by instructions from the target. This is correct
527 if the branch is not taken. Since we are following both
528 paths from the branch, we must also compute correct info
529 if the branch is taken. We do this by inverting all of
530 the INSN_FROM_TARGET_P bits, calling mark_set_resources,
531 and then inverting the INSN_FROM_TARGET_P bits again. */
533 if (GET_CODE (PATTERN (insn)) == SEQUENCE
534 && INSN_ANNULLED_BRANCH_P (this_jump_insn))
536 rtx_sequence *seq = as_a <rtx_sequence *> (PATTERN (insn));
537 for (i = 1; i < seq->len (); i++)
538 INSN_FROM_TARGET_P (seq->element (i))
539 = ! INSN_FROM_TARGET_P (seq->element (i));
542 mark_set_resources (insn, &target_set, 0,
545 for (i = 1; i < seq->len (); i++)
546 INSN_FROM_TARGET_P (seq->element (i))
547 = ! INSN_FROM_TARGET_P (seq->element (i));
549 mark_set_resources (insn, &set, 0, MARK_SRC_DEST_CALL);
553 mark_set_resources (insn, &set, 0, MARK_SRC_DEST_CALL);
558 COPY_HARD_REG_SET (scratch, target_set.regs);
559 AND_COMPL_HARD_REG_SET (scratch, needed.regs);
560 AND_COMPL_HARD_REG_SET (target_res.regs, scratch);
562 fallthrough_res = *res;
563 COPY_HARD_REG_SET (scratch, set.regs);
564 AND_COMPL_HARD_REG_SET (scratch, needed.regs);
565 AND_COMPL_HARD_REG_SET (fallthrough_res.regs, scratch);
567 if (!ANY_RETURN_P (this_jump_insn->jump_label ()))
568 find_dead_or_set_registers
569 (this_jump_insn->jump_target (),
570 &target_res, 0, jump_count, target_set, needed);
571 find_dead_or_set_registers (next_insn,
572 &fallthrough_res, 0, jump_count,
574 IOR_HARD_REG_SET (fallthrough_res.regs, target_res.regs);
575 AND_HARD_REG_SET (res->regs, fallthrough_res.regs);
583 /* Don't try this optimization if we expired our jump count
584 above, since that would mean there may be an infinite loop
585 in the function being compiled. */
591 mark_referenced_resources (insn, &needed, true);
592 mark_set_resources (insn, &set, 0, MARK_SRC_DEST_CALL);
594 COPY_HARD_REG_SET (scratch, set.regs);
595 AND_COMPL_HARD_REG_SET (scratch, needed.regs);
596 AND_COMPL_HARD_REG_SET (res->regs, scratch);
602 /* Given X, a part of an insn, and a pointer to a `struct resource',
603 RES, indicate which resources are modified by the insn. If
604 MARK_TYPE is MARK_SRC_DEST_CALL, also mark resources potentially
605 set by the called routine.
607 If IN_DEST is nonzero, it means we are inside a SET. Otherwise,
608 objects are being referenced instead of set.
610 We never mark the insn as modifying the condition code unless it explicitly
611 SETs CC0 even though this is not totally correct. The reason for this is
612 that we require a SET of CC0 to immediately precede the reference to CC0.
613 So if some other insn sets CC0 as a side-effect, we know it cannot affect
614 our computation and thus may be placed in a delay slot. */
617 mark_set_resources (rtx x, struct resources *res, int in_dest,
618 enum mark_resource_type mark_type)
623 const char *format_ptr;
640 /* These don't set any resources. */
649 /* Called routine modifies the condition code, memory, any registers
650 that aren't saved across calls, global registers and anything
651 explicitly CLOBBERed immediately after the CALL_INSN. */
653 if (mark_type == MARK_SRC_DEST_CALL)
655 rtx_call_insn *call_insn = as_a <rtx_call_insn *> (x);
659 res->cc = res->memory = 1;
661 get_call_reg_set_usage (call_insn, ®s, regs_invalidated_by_call);
662 IOR_HARD_REG_SET (res->regs, regs);
664 for (link = CALL_INSN_FUNCTION_USAGE (call_insn);
665 link; link = XEXP (link, 1))
666 if (GET_CODE (XEXP (link, 0)) == CLOBBER)
667 mark_set_resources (SET_DEST (XEXP (link, 0)), res, 1,
670 /* Check for a REG_SETJMP. If it exists, then we must
671 assume that this call can clobber any register. */
672 if (find_reg_note (call_insn, REG_SETJMP, NULL))
673 SET_HARD_REG_SET (res->regs);
676 /* ... and also what its RTL says it modifies, if anything. */
681 /* An insn consisting of just a CLOBBER (or USE) is just for flow
682 and doesn't actually do anything, so we ignore it. */
684 if (mark_type != MARK_SRC_DEST_CALL
685 && INSN_SETS_ARE_DELAYED (as_a <rtx_insn *> (x)))
689 if (GET_CODE (x) != USE && GET_CODE (x) != CLOBBER)
694 /* If the source of a SET is a CALL, this is actually done by
695 the called routine. So only include it if we are to include the
696 effects of the calling routine. */
698 mark_set_resources (SET_DEST (x), res,
699 (mark_type == MARK_SRC_DEST_CALL
700 || GET_CODE (SET_SRC (x)) != CALL),
703 mark_set_resources (SET_SRC (x), res, 0, MARK_SRC_DEST);
707 mark_set_resources (XEXP (x, 0), res, 1, MARK_SRC_DEST);
712 rtx_sequence *seq = as_a <rtx_sequence *> (x);
713 rtx control = seq->element (0);
714 bool annul_p = JUMP_P (control) && INSN_ANNULLED_BRANCH_P (control);
716 mark_set_resources (control, res, 0, mark_type);
717 for (i = seq->len () - 1; i >= 0; --i)
719 rtx elt = seq->element (i);
720 if (!annul_p && INSN_FROM_TARGET_P (elt))
721 mark_set_resources (elt, res, 0, mark_type);
730 mark_set_resources (XEXP (x, 0), res, 1, MARK_SRC_DEST);
735 mark_set_resources (XEXP (x, 0), res, 1, MARK_SRC_DEST);
736 mark_set_resources (XEXP (XEXP (x, 1), 0), res, 0, MARK_SRC_DEST);
737 mark_set_resources (XEXP (XEXP (x, 1), 1), res, 0, MARK_SRC_DEST);
742 mark_set_resources (XEXP (x, 0), res, in_dest, MARK_SRC_DEST);
743 mark_set_resources (XEXP (x, 1), res, 0, MARK_SRC_DEST);
744 mark_set_resources (XEXP (x, 2), res, 0, MARK_SRC_DEST);
751 res->volatil |= MEM_VOLATILE_P (x);
754 mark_set_resources (XEXP (x, 0), res, 0, MARK_SRC_DEST);
760 if (!REG_P (SUBREG_REG (x)))
761 mark_set_resources (SUBREG_REG (x), res, in_dest, mark_type);
764 unsigned int regno = subreg_regno (x);
765 unsigned int last_regno = regno + subreg_nregs (x);
767 gcc_assert (last_regno <= FIRST_PSEUDO_REGISTER);
768 for (r = regno; r < last_regno; r++)
769 SET_HARD_REG_BIT (res->regs, r);
777 gcc_assert (HARD_REGISTER_P (x));
778 add_to_hard_reg_set (&res->regs, GET_MODE (x), REGNO (x));
782 case UNSPEC_VOLATILE:
784 /* Traditional asm's are always volatile. */
793 res->volatil |= MEM_VOLATILE_P (x);
795 /* For all ASM_OPERANDS, we must traverse the vector of input operands.
796 We can not just fall through here since then we would be confused
797 by the ASM_INPUT rtx inside ASM_OPERANDS, which do not indicate
798 traditional asms unlike their normal usage. */
800 for (i = 0; i < ASM_OPERANDS_INPUT_LENGTH (x); i++)
801 mark_set_resources (ASM_OPERANDS_INPUT (x, i), res, in_dest,
809 /* Process each sub-expression and flag what it needs. */
810 format_ptr = GET_RTX_FORMAT (code);
811 for (i = 0; i < GET_RTX_LENGTH (code); i++)
812 switch (*format_ptr++)
815 mark_set_resources (XEXP (x, i), res, in_dest, mark_type);
819 for (j = 0; j < XVECLEN (x, i); j++)
820 mark_set_resources (XVECEXP (x, i, j), res, in_dest, mark_type);
825 /* Return TRUE if INSN is a return, possibly with a filled delay slot. */
828 return_insn_p (const_rtx insn)
830 if (JUMP_P (insn) && ANY_RETURN_P (PATTERN (insn)))
833 if (NONJUMP_INSN_P (insn) && GET_CODE (PATTERN (insn)) == SEQUENCE)
834 return return_insn_p (XVECEXP (PATTERN (insn), 0, 0));
839 /* Set the resources that are live at TARGET.
841 If TARGET is zero, we refer to the end of the current function and can
842 return our precomputed value.
844 Otherwise, we try to find out what is live by consulting the basic block
845 information. This is tricky, because we must consider the actions of
846 reload and jump optimization, which occur after the basic block information
849 Accordingly, we proceed as follows::
851 We find the previous BARRIER and look at all immediately following labels
852 (with no intervening active insns) to see if any of them start a basic
853 block. If we hit the start of the function first, we use block 0.
855 Once we have found a basic block and a corresponding first insn, we can
856 accurately compute the live status (by starting at a label following a
857 BARRIER, we are immune to actions taken by reload and jump.) Then we
858 scan all insns between that point and our target. For each CLOBBER (or
859 for call-clobbered regs when we pass a CALL_INSN), mark the appropriate
860 registers are dead. For a SET, mark them as live.
862 We have to be careful when using REG_DEAD notes because they are not
863 updated by such things as find_equiv_reg. So keep track of registers
864 marked as dead that haven't been assigned to, and mark them dead at the
865 next CODE_LABEL since reload and jump won't propagate values across labels.
867 If we cannot find the start of a basic block (should be a very rare
868 case, if it can happen at all), mark everything as potentially live.
870 Next, scan forward from TARGET looking for things set or clobbered
871 before they are used. These are not live.
873 Because we can be called many times on the same target, save our results
874 in a hash table indexed by INSN_UID. This is only done if the function
875 init_resource_info () was invoked before we are called. */
878 mark_target_live_regs (rtx_insn *insns, rtx target_maybe_return, struct resources *res)
882 struct target_info *tinfo = NULL;
885 HARD_REG_SET scratch;
886 struct resources set, needed;
888 /* Handle end of function. */
889 if (target_maybe_return == 0 || ANY_RETURN_P (target_maybe_return))
891 *res = end_of_function_needs;
895 /* We've handled the case of RETURN/SIMPLE_RETURN; we should now have an
897 rtx_insn *target = as_a <rtx_insn *> (target_maybe_return);
899 /* Handle return insn. */
900 if (return_insn_p (target))
902 *res = end_of_function_needs;
903 mark_referenced_resources (target, res, false);
907 /* We have to assume memory is needed, but the CC isn't. */
912 /* See if we have computed this value already. */
913 if (target_hash_table != NULL)
915 for (tinfo = target_hash_table[INSN_UID (target) % TARGET_HASH_PRIME];
916 tinfo; tinfo = tinfo->next)
917 if (tinfo->uid == INSN_UID (target))
920 /* Start by getting the basic block number. If we have saved
921 information, we can get it from there unless the insn at the
922 start of the basic block has been deleted. */
923 if (tinfo && tinfo->block != -1
924 && ! BB_HEAD (BASIC_BLOCK_FOR_FN (cfun, tinfo->block))->deleted ())
929 b = find_basic_block (target, MAX_DELAY_SLOT_LIVE_SEARCH);
931 if (target_hash_table != NULL)
935 /* If the information is up-to-date, use it. Otherwise, we will
937 if (b == tinfo->block && b != -1 && tinfo->bb_tick == bb_ticks[b])
939 COPY_HARD_REG_SET (res->regs, tinfo->live_regs);
945 /* Allocate a place to put our results and chain it into the
947 tinfo = XNEW (struct target_info);
948 tinfo->uid = INSN_UID (target);
951 = target_hash_table[INSN_UID (target) % TARGET_HASH_PRIME];
952 target_hash_table[INSN_UID (target) % TARGET_HASH_PRIME] = tinfo;
956 CLEAR_HARD_REG_SET (pending_dead_regs);
958 /* If we found a basic block, get the live registers from it and update
959 them with anything set or killed between its start and the insn before
960 TARGET; this custom life analysis is really about registers so we need
961 to use the LR problem. Otherwise, we must assume everything is live. */
964 regset regs_live = DF_LR_IN (BASIC_BLOCK_FOR_FN (cfun, b));
965 rtx_insn *start_insn, *stop_insn;
967 /* Compute hard regs live at start of block. */
968 REG_SET_TO_HARD_REG_SET (current_live_regs, regs_live);
970 /* Get starting and ending insn, handling the case where each might
972 start_insn = (b == ENTRY_BLOCK_PTR_FOR_FN (cfun)->next_bb->index ?
973 insns : BB_HEAD (BASIC_BLOCK_FOR_FN (cfun, b)));
976 if (NONJUMP_INSN_P (start_insn)
977 && GET_CODE (PATTERN (start_insn)) == SEQUENCE)
978 start_insn = as_a <rtx_sequence *> (PATTERN (start_insn))->insn (0);
980 if (NONJUMP_INSN_P (stop_insn)
981 && GET_CODE (PATTERN (stop_insn)) == SEQUENCE)
982 stop_insn = next_insn (PREV_INSN (stop_insn));
984 for (insn = start_insn; insn != stop_insn;
985 insn = next_insn_no_annul (insn))
988 rtx_insn *real_insn = insn;
989 enum rtx_code code = GET_CODE (insn);
991 if (DEBUG_INSN_P (insn))
994 /* If this insn is from the target of a branch, it isn't going to
995 be used in the sequel. If it is used in both cases, this
996 test will not be true. */
997 if ((code == INSN || code == JUMP_INSN || code == CALL_INSN)
998 && INSN_FROM_TARGET_P (insn))
1001 /* If this insn is a USE made by update_block, we care about the
1004 && GET_CODE (PATTERN (insn)) == USE
1005 && INSN_P (XEXP (PATTERN (insn), 0)))
1006 real_insn = as_a <rtx_insn *> (XEXP (PATTERN (insn), 0));
1008 if (CALL_P (real_insn))
1010 /* Values in call-clobbered registers survive a COND_EXEC CALL
1011 if that is not executed; this matters for resoure use because
1012 they may be used by a complementarily (or more strictly)
1013 predicated instruction, or if the CALL is NORETURN. */
1014 if (GET_CODE (PATTERN (real_insn)) != COND_EXEC)
1016 HARD_REG_SET regs_invalidated_by_this_call;
1017 get_call_reg_set_usage (real_insn,
1018 ®s_invalidated_by_this_call,
1019 regs_invalidated_by_call);
1020 /* CALL clobbers all call-used regs that aren't fixed except
1021 sp, ap, and fp. Do this before setting the result of the
1023 AND_COMPL_HARD_REG_SET (current_live_regs,
1024 regs_invalidated_by_this_call);
1027 /* A CALL_INSN sets any global register live, since it may
1028 have been modified by the call. */
1029 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
1031 SET_HARD_REG_BIT (current_live_regs, i);
1034 /* Mark anything killed in an insn to be deadened at the next
1035 label. Ignore USE insns; the only REG_DEAD notes will be for
1036 parameters. But they might be early. A CALL_INSN will usually
1037 clobber registers used for parameters. It isn't worth bothering
1038 with the unlikely case when it won't. */
1039 if ((NONJUMP_INSN_P (real_insn)
1040 && GET_CODE (PATTERN (real_insn)) != USE
1041 && GET_CODE (PATTERN (real_insn)) != CLOBBER)
1042 || JUMP_P (real_insn)
1043 || CALL_P (real_insn))
1045 for (link = REG_NOTES (real_insn); link; link = XEXP (link, 1))
1046 if (REG_NOTE_KIND (link) == REG_DEAD
1047 && REG_P (XEXP (link, 0))
1048 && REGNO (XEXP (link, 0)) < FIRST_PSEUDO_REGISTER)
1049 add_to_hard_reg_set (&pending_dead_regs,
1050 GET_MODE (XEXP (link, 0)),
1051 REGNO (XEXP (link, 0)));
1053 note_stores (PATTERN (real_insn), update_live_status, NULL);
1055 /* If any registers were unused after this insn, kill them.
1056 These notes will always be accurate. */
1057 for (link = REG_NOTES (real_insn); link; link = XEXP (link, 1))
1058 if (REG_NOTE_KIND (link) == REG_UNUSED
1059 && REG_P (XEXP (link, 0))
1060 && REGNO (XEXP (link, 0)) < FIRST_PSEUDO_REGISTER)
1061 remove_from_hard_reg_set (¤t_live_regs,
1062 GET_MODE (XEXP (link, 0)),
1063 REGNO (XEXP (link, 0)));
1066 else if (LABEL_P (real_insn))
1070 /* A label clobbers the pending dead registers since neither
1071 reload nor jump will propagate a value across a label. */
1072 AND_COMPL_HARD_REG_SET (current_live_regs, pending_dead_regs);
1073 CLEAR_HARD_REG_SET (pending_dead_regs);
1075 /* We must conservatively assume that all registers that used
1076 to be live here still are. The fallthrough edge may have
1077 left a live register uninitialized. */
1078 bb = BLOCK_FOR_INSN (real_insn);
1081 HARD_REG_SET extra_live;
1083 REG_SET_TO_HARD_REG_SET (extra_live, DF_LR_IN (bb));
1084 IOR_HARD_REG_SET (current_live_regs, extra_live);
1088 /* The beginning of the epilogue corresponds to the end of the
1089 RTL chain when there are no epilogue insns. Certain resources
1090 are implicitly required at that point. */
1091 else if (NOTE_P (real_insn)
1092 && NOTE_KIND (real_insn) == NOTE_INSN_EPILOGUE_BEG)
1093 IOR_HARD_REG_SET (current_live_regs, start_of_epilogue_needs.regs);
1096 COPY_HARD_REG_SET (res->regs, current_live_regs);
1100 tinfo->bb_tick = bb_ticks[b];
1104 /* We didn't find the start of a basic block. Assume everything
1105 in use. This should happen only extremely rarely. */
1106 SET_HARD_REG_SET (res->regs);
1108 CLEAR_RESOURCE (&set);
1109 CLEAR_RESOURCE (&needed);
1111 rtx_insn *jump_insn = find_dead_or_set_registers (target, res, &jump_target,
1114 /* If we hit an unconditional branch, we have another way of finding out
1115 what is live: we can see what is live at the branch target and include
1116 anything used but not set before the branch. We add the live
1117 resources found using the test below to those found until now. */
1121 struct resources new_resources;
1122 rtx_insn *stop_insn = next_active_insn (jump_insn);
1124 if (!ANY_RETURN_P (jump_target))
1125 jump_target = next_active_insn (jump_target);
1126 mark_target_live_regs (insns, jump_target, &new_resources);
1127 CLEAR_RESOURCE (&set);
1128 CLEAR_RESOURCE (&needed);
1130 /* Include JUMP_INSN in the needed registers. */
1131 for (insn = target; insn != stop_insn; insn = next_active_insn (insn))
1133 mark_referenced_resources (insn, &needed, true);
1135 COPY_HARD_REG_SET (scratch, needed.regs);
1136 AND_COMPL_HARD_REG_SET (scratch, set.regs);
1137 IOR_HARD_REG_SET (new_resources.regs, scratch);
1139 mark_set_resources (insn, &set, 0, MARK_SRC_DEST_CALL);
1142 IOR_HARD_REG_SET (res->regs, new_resources.regs);
1147 COPY_HARD_REG_SET (tinfo->live_regs, res->regs);
1151 /* Initialize the resources required by mark_target_live_regs ().
1152 This should be invoked before the first call to mark_target_live_regs. */
1155 init_resource_info (rtx_insn *epilogue_insn)
1160 /* Indicate what resources are required to be valid at the end of the current
1161 function. The condition code never is and memory always is.
1162 The stack pointer is needed unless EXIT_IGNORE_STACK is true
1163 and there is an epilogue that restores the original stack pointer
1164 from the frame pointer. Registers used to return the function value
1165 are needed. Registers holding global variables are needed. */
1167 end_of_function_needs.cc = 0;
1168 end_of_function_needs.memory = 1;
1169 CLEAR_HARD_REG_SET (end_of_function_needs.regs);
1171 if (frame_pointer_needed)
1173 SET_HARD_REG_BIT (end_of_function_needs.regs, FRAME_POINTER_REGNUM);
1174 if (!HARD_FRAME_POINTER_IS_FRAME_POINTER)
1175 SET_HARD_REG_BIT (end_of_function_needs.regs,
1176 HARD_FRAME_POINTER_REGNUM);
1178 if (!(frame_pointer_needed
1179 && EXIT_IGNORE_STACK
1181 && !crtl->sp_is_unchanging))
1182 SET_HARD_REG_BIT (end_of_function_needs.regs, STACK_POINTER_REGNUM);
1184 if (crtl->return_rtx != 0)
1185 mark_referenced_resources (crtl->return_rtx,
1186 &end_of_function_needs, true);
1188 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
1189 if (global_regs[i] || EPILOGUE_USES (i))
1190 SET_HARD_REG_BIT (end_of_function_needs.regs, i);
1192 /* The registers required to be live at the end of the function are
1193 represented in the flow information as being dead just prior to
1194 reaching the end of the function. For example, the return of a value
1195 might be represented by a USE of the return register immediately
1196 followed by an unconditional jump to the return label where the
1197 return label is the end of the RTL chain. The end of the RTL chain
1198 is then taken to mean that the return register is live.
1200 This sequence is no longer maintained when epilogue instructions are
1201 added to the RTL chain. To reconstruct the original meaning, the
1202 start of the epilogue (NOTE_INSN_EPILOGUE_BEG) is regarded as the
1203 point where these registers become live (start_of_epilogue_needs).
1204 If epilogue instructions are present, the registers set by those
1205 instructions won't have been processed by flow. Thus, those
1206 registers are additionally required at the end of the RTL chain
1207 (end_of_function_needs). */
1209 start_of_epilogue_needs = end_of_function_needs;
1211 while ((epilogue_insn = next_nonnote_insn (epilogue_insn)))
1213 mark_set_resources (epilogue_insn, &end_of_function_needs, 0,
1214 MARK_SRC_DEST_CALL);
1215 if (return_insn_p (epilogue_insn))
1219 /* Allocate and initialize the tables used by mark_target_live_regs. */
1220 target_hash_table = XCNEWVEC (struct target_info *, TARGET_HASH_PRIME);
1221 bb_ticks = XCNEWVEC (int, last_basic_block_for_fn (cfun));
1223 /* Set the BLOCK_FOR_INSN of each label that starts a basic block. */
1224 FOR_EACH_BB_FN (bb, cfun)
1225 if (LABEL_P (BB_HEAD (bb)))
1226 BLOCK_FOR_INSN (BB_HEAD (bb)) = bb;
1229 /* Free up the resources allocated to mark_target_live_regs (). This
1230 should be invoked after the last call to mark_target_live_regs (). */
1233 free_resource_info (void)
1237 if (target_hash_table != NULL)
1241 for (i = 0; i < TARGET_HASH_PRIME; ++i)
1243 struct target_info *ti = target_hash_table[i];
1247 struct target_info *next = ti->next;
1253 free (target_hash_table);
1254 target_hash_table = NULL;
1257 if (bb_ticks != NULL)
1263 FOR_EACH_BB_FN (bb, cfun)
1264 if (LABEL_P (BB_HEAD (bb)))
1265 BLOCK_FOR_INSN (BB_HEAD (bb)) = NULL;
1268 /* Clear any hashed information that we have stored for INSN. */
1271 clear_hashed_info_for_insn (rtx_insn *insn)
1273 struct target_info *tinfo;
1275 if (target_hash_table != NULL)
1277 for (tinfo = target_hash_table[INSN_UID (insn) % TARGET_HASH_PRIME];
1278 tinfo; tinfo = tinfo->next)
1279 if (tinfo->uid == INSN_UID (insn))
1287 /* Increment the tick count for the basic block that contains INSN. */
1290 incr_ticks_for_insn (rtx_insn *insn)
1292 int b = find_basic_block (insn, MAX_DELAY_SLOT_LIVE_SEARCH);
1298 /* Add TRIAL to the set of resources used at the end of the current
1301 mark_end_of_function_resources (rtx trial, bool include_delayed_effects)
1303 mark_referenced_resources (trial, &end_of_function_needs,
1304 include_delayed_effects);