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 ... */
372 if (GET_CODE (PATTERN (x)) == COND_EXEC)
373 /* In addition to the usual references, also consider all outputs
374 as referenced, to compensate for mark_set_resources treating
375 them as killed. This is similar to ZERO_EXTRACT / STRICT_LOW_PART
376 handling, execpt that we got a partial incidence instead of a partial
378 mark_set_resources (x, res, 0,
379 include_delayed_effects
380 ? MARK_SRC_DEST_CALL : MARK_SRC_DEST);
382 if (! include_delayed_effects
383 && INSN_REFERENCES_ARE_DELAYED (as_a <rtx_insn *> (x)))
386 /* No special processing, just speed up. */
387 mark_referenced_resources (PATTERN (x), res, include_delayed_effects);
394 /* Process each sub-expression and flag what it needs. */
395 format_ptr = GET_RTX_FORMAT (code);
396 for (i = 0; i < GET_RTX_LENGTH (code); i++)
397 switch (*format_ptr++)
400 mark_referenced_resources (XEXP (x, i), res, include_delayed_effects);
404 for (j = 0; j < XVECLEN (x, i); j++)
405 mark_referenced_resources (XVECEXP (x, i, j), res,
406 include_delayed_effects);
411 /* A subroutine of mark_target_live_regs. Search forward from TARGET
412 looking for registers that are set before they are used. These are dead.
413 Stop after passing a few conditional jumps, and/or a small
414 number of unconditional branches. */
417 find_dead_or_set_registers (rtx_insn *target, struct resources *res,
418 rtx *jump_target, int jump_count,
419 struct resources set, struct resources needed)
421 HARD_REG_SET scratch;
424 rtx_insn *jump_insn = 0;
427 for (insn = target; insn; insn = next_insn)
429 rtx_insn *this_insn = insn;
431 next_insn = NEXT_INSN (insn);
433 /* If this instruction can throw an exception, then we don't
434 know where we might end up next. That means that we have to
435 assume that whatever we have already marked as live really is
437 if (can_throw_internal (insn))
440 switch (GET_CODE (insn))
443 /* After a label, any pending dead registers that weren't yet
444 used can be made dead. */
445 AND_COMPL_HARD_REG_SET (pending_dead_regs, needed.regs);
446 AND_COMPL_HARD_REG_SET (res->regs, pending_dead_regs);
447 CLEAR_HARD_REG_SET (pending_dead_regs);
456 if (GET_CODE (PATTERN (insn)) == USE)
458 /* If INSN is a USE made by update_block, we care about the
459 underlying insn. Any registers set by the underlying insn
460 are live since the insn is being done somewhere else. */
461 if (INSN_P (XEXP (PATTERN (insn), 0)))
462 mark_set_resources (XEXP (PATTERN (insn), 0), res, 0,
465 /* All other USE insns are to be ignored. */
468 else if (GET_CODE (PATTERN (insn)) == CLOBBER)
470 else if (rtx_sequence *seq =
471 dyn_cast <rtx_sequence *> (PATTERN (insn)))
473 /* An unconditional jump can be used to fill the delay slot
474 of a call, so search for a JUMP_INSN in any position. */
475 for (i = 0; i < seq->len (); i++)
477 this_insn = seq->insn (i);
478 if (JUMP_P (this_insn))
487 if (rtx_jump_insn *this_jump_insn =
488 dyn_cast <rtx_jump_insn *> (this_insn))
490 if (jump_count++ < 10)
492 if (any_uncondjump_p (this_jump_insn)
493 || ANY_RETURN_P (PATTERN (this_jump_insn)))
495 rtx lab_or_return = this_jump_insn->jump_label ();
496 if (ANY_RETURN_P (lab_or_return))
499 next_insn = as_a <rtx_insn *> (lab_or_return);
504 *jump_target = JUMP_LABEL (this_jump_insn);
507 else if (any_condjump_p (this_jump_insn))
509 struct resources target_set, target_res;
510 struct resources fallthrough_res;
512 /* We can handle conditional branches here by following
513 both paths, and then IOR the results of the two paths
514 together, which will give us registers that are dead
515 on both paths. Since this is expensive, we give it
516 a much higher cost than unconditional branches. The
517 cost was chosen so that we will follow at most 1
518 conditional branch. */
521 if (jump_count >= 10)
524 mark_referenced_resources (insn, &needed, true);
526 /* For an annulled branch, mark_set_resources ignores slots
527 filled by instructions from the target. This is correct
528 if the branch is not taken. Since we are following both
529 paths from the branch, we must also compute correct info
530 if the branch is taken. We do this by inverting all of
531 the INSN_FROM_TARGET_P bits, calling mark_set_resources,
532 and then inverting the INSN_FROM_TARGET_P bits again. */
534 if (GET_CODE (PATTERN (insn)) == SEQUENCE
535 && INSN_ANNULLED_BRANCH_P (this_jump_insn))
537 rtx_sequence *seq = as_a <rtx_sequence *> (PATTERN (insn));
538 for (i = 1; i < seq->len (); i++)
539 INSN_FROM_TARGET_P (seq->element (i))
540 = ! INSN_FROM_TARGET_P (seq->element (i));
543 mark_set_resources (insn, &target_set, 0,
546 for (i = 1; i < seq->len (); i++)
547 INSN_FROM_TARGET_P (seq->element (i))
548 = ! INSN_FROM_TARGET_P (seq->element (i));
550 mark_set_resources (insn, &set, 0, MARK_SRC_DEST_CALL);
554 mark_set_resources (insn, &set, 0, MARK_SRC_DEST_CALL);
559 COPY_HARD_REG_SET (scratch, target_set.regs);
560 AND_COMPL_HARD_REG_SET (scratch, needed.regs);
561 AND_COMPL_HARD_REG_SET (target_res.regs, scratch);
563 fallthrough_res = *res;
564 COPY_HARD_REG_SET (scratch, set.regs);
565 AND_COMPL_HARD_REG_SET (scratch, needed.regs);
566 AND_COMPL_HARD_REG_SET (fallthrough_res.regs, scratch);
568 if (!ANY_RETURN_P (this_jump_insn->jump_label ()))
569 find_dead_or_set_registers
570 (this_jump_insn->jump_target (),
571 &target_res, 0, jump_count, target_set, needed);
572 find_dead_or_set_registers (next_insn,
573 &fallthrough_res, 0, jump_count,
575 IOR_HARD_REG_SET (fallthrough_res.regs, target_res.regs);
576 AND_HARD_REG_SET (res->regs, fallthrough_res.regs);
584 /* Don't try this optimization if we expired our jump count
585 above, since that would mean there may be an infinite loop
586 in the function being compiled. */
592 mark_referenced_resources (insn, &needed, true);
593 mark_set_resources (insn, &set, 0, MARK_SRC_DEST_CALL);
595 COPY_HARD_REG_SET (scratch, set.regs);
596 AND_COMPL_HARD_REG_SET (scratch, needed.regs);
597 AND_COMPL_HARD_REG_SET (res->regs, scratch);
603 /* Given X, a part of an insn, and a pointer to a `struct resource',
604 RES, indicate which resources are modified by the insn. If
605 MARK_TYPE is MARK_SRC_DEST_CALL, also mark resources potentially
606 set by the called routine.
608 If IN_DEST is nonzero, it means we are inside a SET. Otherwise,
609 objects are being referenced instead of set.
611 We never mark the insn as modifying the condition code unless it explicitly
612 SETs CC0 even though this is not totally correct. The reason for this is
613 that we require a SET of CC0 to immediately precede the reference to CC0.
614 So if some other insn sets CC0 as a side-effect, we know it cannot affect
615 our computation and thus may be placed in a delay slot. */
618 mark_set_resources (rtx x, struct resources *res, int in_dest,
619 enum mark_resource_type mark_type)
624 const char *format_ptr;
641 /* These don't set any resources. */
650 /* Called routine modifies the condition code, memory, any registers
651 that aren't saved across calls, global registers and anything
652 explicitly CLOBBERed immediately after the CALL_INSN. */
654 if (mark_type == MARK_SRC_DEST_CALL)
656 rtx_call_insn *call_insn = as_a <rtx_call_insn *> (x);
660 res->cc = res->memory = 1;
662 get_call_reg_set_usage (call_insn, ®s, regs_invalidated_by_call);
663 IOR_HARD_REG_SET (res->regs, regs);
665 for (link = CALL_INSN_FUNCTION_USAGE (call_insn);
666 link; link = XEXP (link, 1))
667 if (GET_CODE (XEXP (link, 0)) == CLOBBER)
668 mark_set_resources (SET_DEST (XEXP (link, 0)), res, 1,
671 /* Check for a REG_SETJMP. If it exists, then we must
672 assume that this call can clobber any register. */
673 if (find_reg_note (call_insn, REG_SETJMP, NULL))
674 SET_HARD_REG_SET (res->regs);
677 /* ... and also what its RTL says it modifies, if anything. */
683 /* An insn consisting of just a CLOBBER (or USE) is just for flow
684 and doesn't actually do anything, so we ignore it. */
686 if (mark_type != MARK_SRC_DEST_CALL
687 && INSN_SETS_ARE_DELAYED (as_a <rtx_insn *> (x)))
691 if (GET_CODE (x) != USE && GET_CODE (x) != CLOBBER)
696 /* If the source of a SET is a CALL, this is actually done by
697 the called routine. So only include it if we are to include the
698 effects of the calling routine. */
700 mark_set_resources (SET_DEST (x), res,
701 (mark_type == MARK_SRC_DEST_CALL
702 || GET_CODE (SET_SRC (x)) != CALL),
705 mark_set_resources (SET_SRC (x), res, 0, MARK_SRC_DEST);
709 mark_set_resources (XEXP (x, 0), res, 1, MARK_SRC_DEST);
714 rtx_sequence *seq = as_a <rtx_sequence *> (x);
715 rtx control = seq->element (0);
716 bool annul_p = JUMP_P (control) && INSN_ANNULLED_BRANCH_P (control);
718 mark_set_resources (control, res, 0, mark_type);
719 for (i = seq->len () - 1; i >= 0; --i)
721 rtx elt = seq->element (i);
722 if (!annul_p && INSN_FROM_TARGET_P (elt))
723 mark_set_resources (elt, res, 0, mark_type);
732 mark_set_resources (XEXP (x, 0), res, 1, MARK_SRC_DEST);
737 mark_set_resources (XEXP (x, 0), res, 1, MARK_SRC_DEST);
738 mark_set_resources (XEXP (XEXP (x, 1), 0), res, 0, MARK_SRC_DEST);
739 mark_set_resources (XEXP (XEXP (x, 1), 1), res, 0, MARK_SRC_DEST);
744 mark_set_resources (XEXP (x, 0), res, in_dest, MARK_SRC_DEST);
745 mark_set_resources (XEXP (x, 1), res, 0, MARK_SRC_DEST);
746 mark_set_resources (XEXP (x, 2), res, 0, MARK_SRC_DEST);
753 res->volatil |= MEM_VOLATILE_P (x);
756 mark_set_resources (XEXP (x, 0), res, 0, MARK_SRC_DEST);
762 if (!REG_P (SUBREG_REG (x)))
763 mark_set_resources (SUBREG_REG (x), res, in_dest, mark_type);
766 unsigned int regno = subreg_regno (x);
767 unsigned int last_regno = regno + subreg_nregs (x);
769 gcc_assert (last_regno <= FIRST_PSEUDO_REGISTER);
770 for (r = regno; r < last_regno; r++)
771 SET_HARD_REG_BIT (res->regs, r);
779 gcc_assert (HARD_REGISTER_P (x));
780 add_to_hard_reg_set (&res->regs, GET_MODE (x), REGNO (x));
784 case UNSPEC_VOLATILE:
786 /* Traditional asm's are always volatile. */
795 res->volatil |= MEM_VOLATILE_P (x);
797 /* For all ASM_OPERANDS, we must traverse the vector of input operands.
798 We can not just fall through here since then we would be confused
799 by the ASM_INPUT rtx inside ASM_OPERANDS, which do not indicate
800 traditional asms unlike their normal usage. */
802 for (i = 0; i < ASM_OPERANDS_INPUT_LENGTH (x); i++)
803 mark_set_resources (ASM_OPERANDS_INPUT (x, i), res, in_dest,
811 /* Process each sub-expression and flag what it needs. */
812 format_ptr = GET_RTX_FORMAT (code);
813 for (i = 0; i < GET_RTX_LENGTH (code); i++)
814 switch (*format_ptr++)
817 mark_set_resources (XEXP (x, i), res, in_dest, mark_type);
821 for (j = 0; j < XVECLEN (x, i); j++)
822 mark_set_resources (XVECEXP (x, i, j), res, in_dest, mark_type);
827 /* Return TRUE if INSN is a return, possibly with a filled delay slot. */
830 return_insn_p (const_rtx insn)
832 if (JUMP_P (insn) && ANY_RETURN_P (PATTERN (insn)))
835 if (NONJUMP_INSN_P (insn) && GET_CODE (PATTERN (insn)) == SEQUENCE)
836 return return_insn_p (XVECEXP (PATTERN (insn), 0, 0));
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 insn, we can
858 accurately compute the live status (by starting at a label following a
859 BARRIER, we are immune to actions taken by reload and jump.) Then we
860 scan all insns between that point and our target. For each CLOBBER (or
861 for call-clobbered regs when we pass a CALL_INSN), mark the appropriate
862 registers are dead. For a SET, mark them as live.
864 We have to be careful when using REG_DEAD notes because they are not
865 updated by such things as find_equiv_reg. So keep track of registers
866 marked as dead that haven't been assigned to, and mark them dead at the
867 next CODE_LABEL since reload and jump won't propagate values across labels.
869 If we cannot find the start of a basic block (should be a very rare
870 case, if it can happen at all), mark everything as potentially live.
872 Next, scan forward from TARGET looking for things set or clobbered
873 before they are used. These are not live.
875 Because we can be called many times on the same target, save our results
876 in a hash table indexed by INSN_UID. This is only done if the function
877 init_resource_info () was invoked before we are called. */
880 mark_target_live_regs (rtx_insn *insns, rtx target_maybe_return, struct resources *res)
884 struct target_info *tinfo = NULL;
887 HARD_REG_SET scratch;
888 struct resources set, needed;
890 /* Handle end of function. */
891 if (target_maybe_return == 0 || ANY_RETURN_P (target_maybe_return))
893 *res = end_of_function_needs;
897 /* We've handled the case of RETURN/SIMPLE_RETURN; we should now have an
899 rtx_insn *target = as_a <rtx_insn *> (target_maybe_return);
901 /* Handle return insn. */
902 if (return_insn_p (target))
904 *res = end_of_function_needs;
905 mark_referenced_resources (target, res, false);
909 /* We have to assume memory is needed, but the CC isn't. */
914 /* See if we have computed this value already. */
915 if (target_hash_table != NULL)
917 for (tinfo = target_hash_table[INSN_UID (target) % TARGET_HASH_PRIME];
918 tinfo; tinfo = tinfo->next)
919 if (tinfo->uid == INSN_UID (target))
922 /* Start by getting the basic block number. If we have saved
923 information, we can get it from there unless the insn at the
924 start of the basic block has been deleted. */
925 if (tinfo && tinfo->block != -1
926 && ! BB_HEAD (BASIC_BLOCK_FOR_FN (cfun, tinfo->block))->deleted ())
931 b = find_basic_block (target, MAX_DELAY_SLOT_LIVE_SEARCH);
933 if (target_hash_table != NULL)
937 /* If the information is up-to-date, use it. Otherwise, we will
939 if (b == tinfo->block && b != -1 && tinfo->bb_tick == bb_ticks[b])
941 COPY_HARD_REG_SET (res->regs, tinfo->live_regs);
947 /* Allocate a place to put our results and chain it into the
949 tinfo = XNEW (struct target_info);
950 tinfo->uid = INSN_UID (target);
953 = target_hash_table[INSN_UID (target) % TARGET_HASH_PRIME];
954 target_hash_table[INSN_UID (target) % TARGET_HASH_PRIME] = tinfo;
958 CLEAR_HARD_REG_SET (pending_dead_regs);
960 /* If we found a basic block, get the live registers from it and update
961 them with anything set or killed between its start and the insn before
962 TARGET; this custom life analysis is really about registers so we need
963 to use the LR problem. Otherwise, we must assume everything is live. */
966 regset regs_live = DF_LR_IN (BASIC_BLOCK_FOR_FN (cfun, b));
967 rtx_insn *start_insn, *stop_insn;
969 /* Compute hard regs live at start of block. */
970 REG_SET_TO_HARD_REG_SET (current_live_regs, regs_live);
972 /* Get starting and ending insn, handling the case where each might
974 start_insn = (b == ENTRY_BLOCK_PTR_FOR_FN (cfun)->next_bb->index ?
975 insns : BB_HEAD (BASIC_BLOCK_FOR_FN (cfun, b)));
978 if (NONJUMP_INSN_P (start_insn)
979 && GET_CODE (PATTERN (start_insn)) == SEQUENCE)
980 start_insn = as_a <rtx_sequence *> (PATTERN (start_insn))->insn (0);
982 if (NONJUMP_INSN_P (stop_insn)
983 && GET_CODE (PATTERN (stop_insn)) == SEQUENCE)
984 stop_insn = next_insn (PREV_INSN (stop_insn));
986 for (insn = start_insn; insn != stop_insn;
987 insn = next_insn_no_annul (insn))
990 rtx_insn *real_insn = insn;
991 enum rtx_code code = GET_CODE (insn);
993 if (DEBUG_INSN_P (insn))
996 /* If this insn is from the target of a branch, it isn't going to
997 be used in the sequel. If it is used in both cases, this
998 test will not be true. */
999 if ((code == INSN || code == JUMP_INSN || code == CALL_INSN)
1000 && INSN_FROM_TARGET_P (insn))
1003 /* If this insn is a USE made by update_block, we care about the
1006 && GET_CODE (PATTERN (insn)) == USE
1007 && INSN_P (XEXP (PATTERN (insn), 0)))
1008 real_insn = as_a <rtx_insn *> (XEXP (PATTERN (insn), 0));
1010 if (CALL_P (real_insn))
1012 /* Values in call-clobbered registers survive a COND_EXEC CALL
1013 if that is not executed; this matters for resoure use because
1014 they may be used by a complementarily (or more strictly)
1015 predicated instruction, or if the CALL is NORETURN. */
1016 if (GET_CODE (PATTERN (real_insn)) != COND_EXEC)
1018 HARD_REG_SET regs_invalidated_by_this_call;
1019 get_call_reg_set_usage (real_insn,
1020 ®s_invalidated_by_this_call,
1021 regs_invalidated_by_call);
1022 /* CALL clobbers all call-used regs that aren't fixed except
1023 sp, ap, and fp. Do this before setting the result of the
1025 AND_COMPL_HARD_REG_SET (current_live_regs,
1026 regs_invalidated_by_this_call);
1029 /* A CALL_INSN sets any global register live, since it may
1030 have been modified by the call. */
1031 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
1033 SET_HARD_REG_BIT (current_live_regs, i);
1036 /* Mark anything killed in an insn to be deadened at the next
1037 label. Ignore USE insns; the only REG_DEAD notes will be for
1038 parameters. But they might be early. A CALL_INSN will usually
1039 clobber registers used for parameters. It isn't worth bothering
1040 with the unlikely case when it won't. */
1041 if ((NONJUMP_INSN_P (real_insn)
1042 && GET_CODE (PATTERN (real_insn)) != USE
1043 && GET_CODE (PATTERN (real_insn)) != CLOBBER)
1044 || JUMP_P (real_insn)
1045 || CALL_P (real_insn))
1047 for (link = REG_NOTES (real_insn); link; link = XEXP (link, 1))
1048 if (REG_NOTE_KIND (link) == REG_DEAD
1049 && REG_P (XEXP (link, 0))
1050 && REGNO (XEXP (link, 0)) < FIRST_PSEUDO_REGISTER)
1051 add_to_hard_reg_set (&pending_dead_regs,
1052 GET_MODE (XEXP (link, 0)),
1053 REGNO (XEXP (link, 0)));
1055 note_stores (PATTERN (real_insn), update_live_status, NULL);
1057 /* If any registers were unused after this insn, kill them.
1058 These notes will always be accurate. */
1059 for (link = REG_NOTES (real_insn); link; link = XEXP (link, 1))
1060 if (REG_NOTE_KIND (link) == REG_UNUSED
1061 && REG_P (XEXP (link, 0))
1062 && REGNO (XEXP (link, 0)) < FIRST_PSEUDO_REGISTER)
1063 remove_from_hard_reg_set (¤t_live_regs,
1064 GET_MODE (XEXP (link, 0)),
1065 REGNO (XEXP (link, 0)));
1068 else if (LABEL_P (real_insn))
1072 /* A label clobbers the pending dead registers since neither
1073 reload nor jump will propagate a value across a label. */
1074 AND_COMPL_HARD_REG_SET (current_live_regs, pending_dead_regs);
1075 CLEAR_HARD_REG_SET (pending_dead_regs);
1077 /* We must conservatively assume that all registers that used
1078 to be live here still are. The fallthrough edge may have
1079 left a live register uninitialized. */
1080 bb = BLOCK_FOR_INSN (real_insn);
1083 HARD_REG_SET extra_live;
1085 REG_SET_TO_HARD_REG_SET (extra_live, DF_LR_IN (bb));
1086 IOR_HARD_REG_SET (current_live_regs, extra_live);
1090 /* The beginning of the epilogue corresponds to the end of the
1091 RTL chain when there are no epilogue insns. Certain resources
1092 are implicitly required at that point. */
1093 else if (NOTE_P (real_insn)
1094 && NOTE_KIND (real_insn) == NOTE_INSN_EPILOGUE_BEG)
1095 IOR_HARD_REG_SET (current_live_regs, start_of_epilogue_needs.regs);
1098 COPY_HARD_REG_SET (res->regs, current_live_regs);
1102 tinfo->bb_tick = bb_ticks[b];
1106 /* We didn't find the start of a basic block. Assume everything
1107 in use. This should happen only extremely rarely. */
1108 SET_HARD_REG_SET (res->regs);
1110 CLEAR_RESOURCE (&set);
1111 CLEAR_RESOURCE (&needed);
1113 rtx_insn *jump_insn = find_dead_or_set_registers (target, res, &jump_target,
1116 /* If we hit an unconditional branch, we have another way of finding out
1117 what is live: we can see what is live at the branch target and include
1118 anything used but not set before the branch. We add the live
1119 resources found using the test below to those found until now. */
1123 struct resources new_resources;
1124 rtx_insn *stop_insn = next_active_insn (jump_insn);
1126 if (!ANY_RETURN_P (jump_target))
1127 jump_target = next_active_insn (jump_target);
1128 mark_target_live_regs (insns, jump_target, &new_resources);
1129 CLEAR_RESOURCE (&set);
1130 CLEAR_RESOURCE (&needed);
1132 /* Include JUMP_INSN in the needed registers. */
1133 for (insn = target; insn != stop_insn; insn = next_active_insn (insn))
1135 mark_referenced_resources (insn, &needed, true);
1137 COPY_HARD_REG_SET (scratch, needed.regs);
1138 AND_COMPL_HARD_REG_SET (scratch, set.regs);
1139 IOR_HARD_REG_SET (new_resources.regs, scratch);
1141 mark_set_resources (insn, &set, 0, MARK_SRC_DEST_CALL);
1144 IOR_HARD_REG_SET (res->regs, new_resources.regs);
1149 COPY_HARD_REG_SET (tinfo->live_regs, res->regs);
1153 /* Initialize the resources required by mark_target_live_regs ().
1154 This should be invoked before the first call to mark_target_live_regs. */
1157 init_resource_info (rtx_insn *epilogue_insn)
1162 /* Indicate what resources are required to be valid at the end of the current
1163 function. The condition code never is and memory always is.
1164 The stack pointer is needed unless EXIT_IGNORE_STACK is true
1165 and there is an epilogue that restores the original stack pointer
1166 from the frame pointer. Registers used to return the function value
1167 are needed. Registers holding global variables are needed. */
1169 end_of_function_needs.cc = 0;
1170 end_of_function_needs.memory = 1;
1171 CLEAR_HARD_REG_SET (end_of_function_needs.regs);
1173 if (frame_pointer_needed)
1175 SET_HARD_REG_BIT (end_of_function_needs.regs, FRAME_POINTER_REGNUM);
1176 if (!HARD_FRAME_POINTER_IS_FRAME_POINTER)
1177 SET_HARD_REG_BIT (end_of_function_needs.regs,
1178 HARD_FRAME_POINTER_REGNUM);
1180 if (!(frame_pointer_needed
1181 && EXIT_IGNORE_STACK
1183 && !crtl->sp_is_unchanging))
1184 SET_HARD_REG_BIT (end_of_function_needs.regs, STACK_POINTER_REGNUM);
1186 if (crtl->return_rtx != 0)
1187 mark_referenced_resources (crtl->return_rtx,
1188 &end_of_function_needs, true);
1190 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
1191 if (global_regs[i] || EPILOGUE_USES (i))
1192 SET_HARD_REG_BIT (end_of_function_needs.regs, i);
1194 /* The registers required to be live at the end of the function are
1195 represented in the flow information as being dead just prior to
1196 reaching the end of the function. For example, the return of a value
1197 might be represented by a USE of the return register immediately
1198 followed by an unconditional jump to the return label where the
1199 return label is the end of the RTL chain. The end of the RTL chain
1200 is then taken to mean that the return register is live.
1202 This sequence is no longer maintained when epilogue instructions are
1203 added to the RTL chain. To reconstruct the original meaning, the
1204 start of the epilogue (NOTE_INSN_EPILOGUE_BEG) is regarded as the
1205 point where these registers become live (start_of_epilogue_needs).
1206 If epilogue instructions are present, the registers set by those
1207 instructions won't have been processed by flow. Thus, those
1208 registers are additionally required at the end of the RTL chain
1209 (end_of_function_needs). */
1211 start_of_epilogue_needs = end_of_function_needs;
1213 while ((epilogue_insn = next_nonnote_insn (epilogue_insn)))
1215 mark_set_resources (epilogue_insn, &end_of_function_needs, 0,
1216 MARK_SRC_DEST_CALL);
1217 if (return_insn_p (epilogue_insn))
1221 /* Allocate and initialize the tables used by mark_target_live_regs. */
1222 target_hash_table = XCNEWVEC (struct target_info *, TARGET_HASH_PRIME);
1223 bb_ticks = XCNEWVEC (int, last_basic_block_for_fn (cfun));
1225 /* Set the BLOCK_FOR_INSN of each label that starts a basic block. */
1226 FOR_EACH_BB_FN (bb, cfun)
1227 if (LABEL_P (BB_HEAD (bb)))
1228 BLOCK_FOR_INSN (BB_HEAD (bb)) = bb;
1231 /* Free up the resources allocated to mark_target_live_regs (). This
1232 should be invoked after the last call to mark_target_live_regs (). */
1235 free_resource_info (void)
1239 if (target_hash_table != NULL)
1243 for (i = 0; i < TARGET_HASH_PRIME; ++i)
1245 struct target_info *ti = target_hash_table[i];
1249 struct target_info *next = ti->next;
1255 free (target_hash_table);
1256 target_hash_table = NULL;
1259 if (bb_ticks != NULL)
1265 FOR_EACH_BB_FN (bb, cfun)
1266 if (LABEL_P (BB_HEAD (bb)))
1267 BLOCK_FOR_INSN (BB_HEAD (bb)) = NULL;
1270 /* Clear any hashed information that we have stored for INSN. */
1273 clear_hashed_info_for_insn (rtx_insn *insn)
1275 struct target_info *tinfo;
1277 if (target_hash_table != NULL)
1279 for (tinfo = target_hash_table[INSN_UID (insn) % TARGET_HASH_PRIME];
1280 tinfo; tinfo = tinfo->next)
1281 if (tinfo->uid == INSN_UID (insn))
1289 /* Increment the tick count for the basic block that contains INSN. */
1292 incr_ticks_for_insn (rtx_insn *insn)
1294 int b = find_basic_block (insn, MAX_DELAY_SLOT_LIVE_SEARCH);
1300 /* Add TRIAL to the set of resources used at the end of the current
1303 mark_end_of_function_resources (rtx trial, bool include_delayed_effects)
1305 mark_referenced_resources (trial, &end_of_function_needs,
1306 include_delayed_effects);