1 /* Data flow analysis for GNU compiler.
2 Copyright (C) 1987, 1988, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
3 1999, 2000, 2001, 2002, 2003, 2004 Free Software Foundation, Inc.
5 This file is part of GCC.
7 GCC is free software; you can redistribute it and/or modify it under
8 the terms of the GNU General Public License as published by the Free
9 Software Foundation; either version 2, or (at your option) any later
12 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
13 WARRANTY; without even the implied warranty of MERCHANTABILITY or
14 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
17 You should have received a copy of the GNU General Public License
18 along with GCC; see the file COPYING. If not, write to the Free
19 Software Foundation, 59 Temple Place - Suite 330, Boston, MA
22 /* This file contains the data flow analysis pass of the compiler. It
23 computes data flow information which tells combine_instructions
24 which insns to consider combining and controls register allocation.
26 Additional data flow information that is too bulky to record is
27 generated during the analysis, and is used at that time to create
28 autoincrement and autodecrement addressing.
30 The first step is dividing the function into basic blocks.
31 find_basic_blocks does this. Then life_analysis determines
32 where each register is live and where it is dead.
34 ** find_basic_blocks **
36 find_basic_blocks divides the current function's rtl into basic
37 blocks and constructs the CFG. The blocks are recorded in the
38 basic_block_info array; the CFG exists in the edge structures
39 referenced by the blocks.
41 find_basic_blocks also finds any unreachable loops and deletes them.
45 life_analysis is called immediately after find_basic_blocks.
46 It uses the basic block information to determine where each
47 hard or pseudo register is live.
49 ** live-register info **
51 The information about where each register is live is in two parts:
52 the REG_NOTES of insns, and the vector basic_block->global_live_at_start.
54 basic_block->global_live_at_start has an element for each basic
55 block, and the element is a bit-vector with a bit for each hard or
56 pseudo register. The bit is 1 if the register is live at the
57 beginning of the basic block.
59 Two types of elements can be added to an insn's REG_NOTES.
60 A REG_DEAD note is added to an insn's REG_NOTES for any register
61 that meets both of two conditions: The value in the register is not
62 needed in subsequent insns and the insn does not replace the value in
63 the register (in the case of multi-word hard registers, the value in
64 each register must be replaced by the insn to avoid a REG_DEAD note).
66 In the vast majority of cases, an object in a REG_DEAD note will be
67 used somewhere in the insn. The (rare) exception to this is if an
68 insn uses a multi-word hard register and only some of the registers are
69 needed in subsequent insns. In that case, REG_DEAD notes will be
70 provided for those hard registers that are not subsequently needed.
71 Partial REG_DEAD notes of this type do not occur when an insn sets
72 only some of the hard registers used in such a multi-word operand;
73 omitting REG_DEAD notes for objects stored in an insn is optional and
74 the desire to do so does not justify the complexity of the partial
77 REG_UNUSED notes are added for each register that is set by the insn
78 but is unused subsequently (if every register set by the insn is unused
79 and the insn does not reference memory or have some other side-effect,
80 the insn is deleted instead). If only part of a multi-word hard
81 register is used in a subsequent insn, REG_UNUSED notes are made for
82 the parts that will not be used.
84 To determine which registers are live after any insn, one can
85 start from the beginning of the basic block and scan insns, noting
86 which registers are set by each insn and which die there.
88 ** Other actions of life_analysis **
90 life_analysis sets up the LOG_LINKS fields of insns because the
91 information needed to do so is readily available.
93 life_analysis deletes insns whose only effect is to store a value
96 life_analysis notices cases where a reference to a register as
97 a memory address can be combined with a preceding or following
98 incrementation or decrementation of the register. The separate
99 instruction to increment or decrement is deleted and the address
100 is changed to a POST_INC or similar rtx.
102 Each time an incrementing or decrementing address is created,
103 a REG_INC element is added to the insn's REG_NOTES list.
105 life_analysis fills in certain vectors containing information about
106 register usage: REG_N_REFS, REG_N_DEATHS, REG_N_SETS, REG_LIVE_LENGTH,
107 REG_N_CALLS_CROSSED, REG_N_THROWING_CALLS_CROSSED and REG_BASIC_BLOCK.
109 life_analysis sets current_function_sp_is_unchanging if the function
110 doesn't modify the stack pointer. */
114 Split out from life_analysis:
115 - local property discovery (bb->local_live, bb->local_set)
116 - global property computation
118 - pre/post modify transformation
123 #include "coretypes.h"
128 #include "hard-reg-set.h"
129 #include "basic-block.h"
130 #include "insn-config.h"
134 #include "function.h"
142 #include "splay-tree.h"
144 #ifndef HAVE_epilogue
145 #define HAVE_epilogue 0
147 #ifndef HAVE_prologue
148 #define HAVE_prologue 0
150 #ifndef HAVE_sibcall_epilogue
151 #define HAVE_sibcall_epilogue 0
154 #ifndef EPILOGUE_USES
155 #define EPILOGUE_USES(REGNO) 0
158 #define EH_USES(REGNO) 0
161 #ifdef HAVE_conditional_execution
162 #ifndef REVERSE_CONDEXEC_PREDICATES_P
163 #define REVERSE_CONDEXEC_PREDICATES_P(x, y) ((x) == reverse_condition (y))
167 /* Nonzero if the second flow pass has completed. */
170 /* Maximum register number used in this function, plus one. */
174 /* Indexed by n, giving various register information */
176 varray_type reg_n_info
;
178 /* Size of a regset for the current function,
179 in (1) bytes and (2) elements. */
184 /* Regset of regs live when calls to `setjmp'-like functions happen. */
185 /* ??? Does this exist only for the setjmp-clobbered warning message? */
187 regset regs_live_at_setjmp
;
189 /* List made of EXPR_LIST rtx's which gives pairs of pseudo registers
190 that have to go in the same hard reg.
191 The first two regs in the list are a pair, and the next two
192 are another pair, etc. */
195 /* Callback that determines if it's ok for a function to have no
196 noreturn attribute. */
197 int (*lang_missing_noreturn_ok_p
) (tree
);
199 /* Set of registers that may be eliminable. These are handled specially
200 in updating regs_ever_live. */
202 static HARD_REG_SET elim_reg_set
;
204 /* Holds information for tracking conditional register life information. */
205 struct reg_cond_life_info
207 /* A boolean expression of conditions under which a register is dead. */
209 /* Conditions under which a register is dead at the basic block end. */
212 /* A boolean expression of conditions under which a register has been
216 /* ??? Could store mask of bytes that are dead, so that we could finally
217 track lifetimes of multi-word registers accessed via subregs. */
220 /* For use in communicating between propagate_block and its subroutines.
221 Holds all information needed to compute life and def-use information. */
223 struct propagate_block_info
225 /* The basic block we're considering. */
228 /* Bit N is set if register N is conditionally or unconditionally live. */
231 /* Bit N is set if register N is set this insn. */
234 /* Element N is the next insn that uses (hard or pseudo) register N
235 within the current basic block; or zero, if there is no such insn. */
238 /* Contains a list of all the MEMs we are tracking for dead store
242 /* If non-null, record the set of registers set unconditionally in the
246 /* If non-null, record the set of registers set conditionally in the
248 regset cond_local_set
;
250 #ifdef HAVE_conditional_execution
251 /* Indexed by register number, holds a reg_cond_life_info for each
252 register that is not unconditionally live or dead. */
253 splay_tree reg_cond_dead
;
255 /* Bit N is set if register N is in an expression in reg_cond_dead. */
259 /* The length of mem_set_list. */
260 int mem_set_list_len
;
262 /* Nonzero if the value of CC0 is live. */
265 /* Flags controlling the set of information propagate_block collects. */
269 /* Number of dead insns removed. */
272 /* Maximum length of pbi->mem_set_list before we start dropping
273 new elements on the floor. */
274 #define MAX_MEM_SET_LIST_LEN 100
276 /* Forward declarations */
277 static int verify_wide_reg_1 (rtx
*, void *);
278 static void verify_wide_reg (int, basic_block
);
279 static void verify_local_live_at_start (regset
, basic_block
);
280 static void notice_stack_pointer_modification_1 (rtx
, rtx
, void *);
281 static void notice_stack_pointer_modification (rtx
);
282 static void mark_reg (rtx
, void *);
283 static void mark_regs_live_at_end (regset
);
284 static void calculate_global_regs_live (sbitmap
, sbitmap
, int);
285 static void propagate_block_delete_insn (rtx
);
286 static rtx
propagate_block_delete_libcall (rtx
, rtx
);
287 static int insn_dead_p (struct propagate_block_info
*, rtx
, int, rtx
);
288 static int libcall_dead_p (struct propagate_block_info
*, rtx
, rtx
);
289 static void mark_set_regs (struct propagate_block_info
*, rtx
, rtx
);
290 static void mark_set_1 (struct propagate_block_info
*, enum rtx_code
, rtx
,
292 static int find_regno_partial (rtx
*, void *);
294 #ifdef HAVE_conditional_execution
295 static int mark_regno_cond_dead (struct propagate_block_info
*, int, rtx
);
296 static void free_reg_cond_life_info (splay_tree_value
);
297 static int flush_reg_cond_reg_1 (splay_tree_node
, void *);
298 static void flush_reg_cond_reg (struct propagate_block_info
*, int);
299 static rtx
elim_reg_cond (rtx
, unsigned int);
300 static rtx
ior_reg_cond (rtx
, rtx
, int);
301 static rtx
not_reg_cond (rtx
);
302 static rtx
and_reg_cond (rtx
, rtx
, int);
305 static void attempt_auto_inc (struct propagate_block_info
*, rtx
, rtx
, rtx
,
307 static void find_auto_inc (struct propagate_block_info
*, rtx
, rtx
);
308 static int try_pre_increment_1 (struct propagate_block_info
*, rtx
);
309 static int try_pre_increment (rtx
, rtx
, HOST_WIDE_INT
);
311 static void mark_used_reg (struct propagate_block_info
*, rtx
, rtx
, rtx
);
312 static void mark_used_regs (struct propagate_block_info
*, rtx
, rtx
, rtx
);
313 void debug_flow_info (void);
314 static void add_to_mem_set_list (struct propagate_block_info
*, rtx
);
315 static int invalidate_mems_from_autoinc (rtx
*, void *);
316 static void invalidate_mems_from_set (struct propagate_block_info
*, rtx
);
317 static void clear_log_links (sbitmap
);
318 static int count_or_remove_death_notes_bb (basic_block
, int);
322 check_function_return_warnings (void)
324 if (warn_missing_noreturn
325 && !TREE_THIS_VOLATILE (cfun
->decl
)
326 && EXIT_BLOCK_PTR
->pred
== NULL
327 && (lang_missing_noreturn_ok_p
328 && !lang_missing_noreturn_ok_p (cfun
->decl
)))
329 warning ("function might be possible candidate for attribute `noreturn'");
331 /* If we have a path to EXIT, then we do return. */
332 if (TREE_THIS_VOLATILE (cfun
->decl
)
333 && EXIT_BLOCK_PTR
->pred
!= NULL
)
334 warning ("`noreturn' function does return");
336 /* If the clobber_return_insn appears in some basic block, then we
337 do reach the end without returning a value. */
338 else if (warn_return_type
339 && cfun
->x_clobber_return_insn
!= NULL
340 && EXIT_BLOCK_PTR
->pred
!= NULL
)
342 int max_uid
= get_max_uid ();
344 /* If clobber_return_insn was excised by jump1, then renumber_insns
345 can make max_uid smaller than the number still recorded in our rtx.
346 That's fine, since this is a quick way of verifying that the insn
347 is no longer in the chain. */
348 if (INSN_UID (cfun
->x_clobber_return_insn
) < max_uid
)
352 for (insn
= get_insns (); insn
; insn
= NEXT_INSN (insn
))
353 if (insn
== cfun
->x_clobber_return_insn
)
355 warning ("control reaches end of non-void function");
362 /* Return the INSN immediately following the NOTE_INSN_BASIC_BLOCK
363 note associated with the BLOCK. */
366 first_insn_after_basic_block_note (basic_block block
)
370 /* Get the first instruction in the block. */
371 insn
= BB_HEAD (block
);
373 if (insn
== NULL_RTX
)
375 if (GET_CODE (insn
) == CODE_LABEL
)
376 insn
= NEXT_INSN (insn
);
377 if (!NOTE_INSN_BASIC_BLOCK_P (insn
))
380 return NEXT_INSN (insn
);
383 /* Perform data flow analysis.
384 F is the first insn of the function; FLAGS is a set of PROP_* flags
385 to be used in accumulating flow info. */
388 life_analysis (rtx f
, FILE *file
, int flags
)
390 #ifdef ELIMINABLE_REGS
392 static const struct {const int from
, to
; } eliminables
[] = ELIMINABLE_REGS
;
395 /* Record which registers will be eliminated. We use this in
398 CLEAR_HARD_REG_SET (elim_reg_set
);
400 #ifdef ELIMINABLE_REGS
401 for (i
= 0; i
< (int) ARRAY_SIZE (eliminables
); i
++)
402 SET_HARD_REG_BIT (elim_reg_set
, eliminables
[i
].from
);
404 SET_HARD_REG_BIT (elim_reg_set
, FRAME_POINTER_REGNUM
);
408 #ifdef CANNOT_CHANGE_MODE_CLASS
409 if (flags
& PROP_REG_INFO
)
410 init_subregs_of_mode ();
414 flags
&= ~(PROP_LOG_LINKS
| PROP_AUTOINC
| PROP_ALLOW_CFG_CHANGES
);
416 /* The post-reload life analysis have (on a global basis) the same
417 registers live as was computed by reload itself. elimination
418 Otherwise offsets and such may be incorrect.
420 Reload will make some registers as live even though they do not
423 We don't want to create new auto-incs after reload, since they
424 are unlikely to be useful and can cause problems with shared
426 if (reload_completed
)
427 flags
&= ~(PROP_REG_INFO
| PROP_AUTOINC
);
429 /* We want alias analysis information for local dead store elimination. */
430 if (optimize
&& (flags
& PROP_SCAN_DEAD_STORES
))
431 init_alias_analysis ();
433 /* Always remove no-op moves. Do this before other processing so
434 that we don't have to keep re-scanning them. */
435 delete_noop_moves (f
);
437 /* Some targets can emit simpler epilogues if they know that sp was
438 not ever modified during the function. After reload, of course,
439 we've already emitted the epilogue so there's no sense searching. */
440 if (! reload_completed
)
441 notice_stack_pointer_modification (f
);
443 /* Allocate and zero out data structures that will record the
444 data from lifetime analysis. */
445 allocate_reg_life_data ();
446 allocate_bb_life_data ();
448 /* Find the set of registers live on function exit. */
449 mark_regs_live_at_end (EXIT_BLOCK_PTR
->global_live_at_start
);
451 /* "Update" life info from zero. It'd be nice to begin the
452 relaxation with just the exit and noreturn blocks, but that set
453 is not immediately handy. */
455 if (flags
& PROP_REG_INFO
)
457 memset (regs_ever_live
, 0, sizeof (regs_ever_live
));
458 memset (regs_asm_clobbered
, 0, sizeof (regs_asm_clobbered
));
460 update_life_info (NULL
, UPDATE_LIFE_GLOBAL
, flags
);
463 if (optimize
&& (flags
& PROP_SCAN_DEAD_STORES
))
464 end_alias_analysis ();
467 dump_flow_info (file
);
469 free_basic_block_vars (1);
471 /* Removing dead insns should've made jumptables really dead. */
472 delete_dead_jumptables ();
475 /* A subroutine of verify_wide_reg, called through for_each_rtx.
476 Search for REGNO. If found, return 2 if it is not wider than
480 verify_wide_reg_1 (rtx
*px
, void *pregno
)
483 unsigned int regno
= *(int *) pregno
;
485 if (GET_CODE (x
) == REG
&& REGNO (x
) == regno
)
487 if (GET_MODE_BITSIZE (GET_MODE (x
)) <= BITS_PER_WORD
)
494 /* A subroutine of verify_local_live_at_start. Search through insns
495 of BB looking for register REGNO. */
498 verify_wide_reg (int regno
, basic_block bb
)
500 rtx head
= BB_HEAD (bb
), end
= BB_END (bb
);
506 int r
= for_each_rtx (&PATTERN (head
), verify_wide_reg_1
, ®no
);
514 head
= NEXT_INSN (head
);
519 fprintf (rtl_dump_file
, "Register %d died unexpectedly.\n", regno
);
520 dump_bb (bb
, rtl_dump_file
);
525 /* A subroutine of update_life_info. Verify that there are no untoward
526 changes in live_at_start during a local update. */
529 verify_local_live_at_start (regset new_live_at_start
, basic_block bb
)
531 if (reload_completed
)
533 /* After reload, there are no pseudos, nor subregs of multi-word
534 registers. The regsets should exactly match. */
535 if (! REG_SET_EQUAL_P (new_live_at_start
, bb
->global_live_at_start
))
539 fprintf (rtl_dump_file
,
540 "live_at_start mismatch in bb %d, aborting\nNew:\n",
542 debug_bitmap_file (rtl_dump_file
, new_live_at_start
);
543 fputs ("Old:\n", rtl_dump_file
);
544 dump_bb (bb
, rtl_dump_file
);
553 /* Find the set of changed registers. */
554 XOR_REG_SET (new_live_at_start
, bb
->global_live_at_start
);
556 EXECUTE_IF_SET_IN_REG_SET (new_live_at_start
, 0, i
,
558 /* No registers should die. */
559 if (REGNO_REG_SET_P (bb
->global_live_at_start
, i
))
563 fprintf (rtl_dump_file
,
564 "Register %d died unexpectedly.\n", i
);
565 dump_bb (bb
, rtl_dump_file
);
570 /* Verify that the now-live register is wider than word_mode. */
571 verify_wide_reg (i
, bb
);
576 /* Updates life information starting with the basic blocks set in BLOCKS.
577 If BLOCKS is null, consider it to be the universal set.
579 If EXTENT is UPDATE_LIFE_LOCAL, such as after splitting or peepholing,
580 we are only expecting local modifications to basic blocks. If we find
581 extra registers live at the beginning of a block, then we either killed
582 useful data, or we have a broken split that wants data not provided.
583 If we find registers removed from live_at_start, that means we have
584 a broken peephole that is killing a register it shouldn't.
586 ??? This is not true in one situation -- when a pre-reload splitter
587 generates subregs of a multi-word pseudo, current life analysis will
588 lose the kill. So we _can_ have a pseudo go live. How irritating.
590 It is also not true when a peephole decides that it doesn't need one
591 or more of the inputs.
593 Including PROP_REG_INFO does not properly refresh regs_ever_live
594 unless the caller resets it to zero. */
597 update_life_info (sbitmap blocks
, enum update_life_extent extent
, int prop_flags
)
600 regset_head tmp_head
;
602 int stabilized_prop_flags
= prop_flags
;
605 tmp
= INITIALIZE_REG_SET (tmp_head
);
608 timevar_push ((extent
== UPDATE_LIFE_LOCAL
|| blocks
)
609 ? TV_LIFE_UPDATE
: TV_LIFE
);
611 /* Changes to the CFG are only allowed when
612 doing a global update for the entire CFG. */
613 if ((prop_flags
& PROP_ALLOW_CFG_CHANGES
)
614 && (extent
== UPDATE_LIFE_LOCAL
|| blocks
))
617 /* For a global update, we go through the relaxation process again. */
618 if (extent
!= UPDATE_LIFE_LOCAL
)
624 calculate_global_regs_live (blocks
, blocks
,
625 prop_flags
& (PROP_SCAN_DEAD_CODE
626 | PROP_SCAN_DEAD_STORES
627 | PROP_ALLOW_CFG_CHANGES
));
629 if ((prop_flags
& (PROP_KILL_DEAD_CODE
| PROP_ALLOW_CFG_CHANGES
))
630 != (PROP_KILL_DEAD_CODE
| PROP_ALLOW_CFG_CHANGES
))
633 /* Removing dead code may allow the CFG to be simplified which
634 in turn may allow for further dead code detection / removal. */
635 FOR_EACH_BB_REVERSE (bb
)
637 COPY_REG_SET (tmp
, bb
->global_live_at_end
);
638 changed
|= propagate_block (bb
, tmp
, NULL
, NULL
,
639 prop_flags
& (PROP_SCAN_DEAD_CODE
640 | PROP_SCAN_DEAD_STORES
641 | PROP_KILL_DEAD_CODE
));
644 /* Don't pass PROP_SCAN_DEAD_CODE or PROP_KILL_DEAD_CODE to
645 subsequent propagate_block calls, since removing or acting as
646 removing dead code can affect global register liveness, which
647 is supposed to be finalized for this call after this loop. */
648 stabilized_prop_flags
649 &= ~(PROP_SCAN_DEAD_CODE
| PROP_SCAN_DEAD_STORES
650 | PROP_KILL_DEAD_CODE
);
655 /* We repeat regardless of what cleanup_cfg says. If there were
656 instructions deleted above, that might have been only a
657 partial improvement (see MAX_MEM_SET_LIST_LEN usage).
658 Further improvement may be possible. */
659 cleanup_cfg (CLEANUP_EXPENSIVE
);
661 /* Zap the life information from the last round. If we don't
662 do this, we can wind up with registers that no longer appear
663 in the code being marked live at entry, which twiggs bogus
664 warnings from regno_uninitialized. */
667 CLEAR_REG_SET (bb
->global_live_at_start
);
668 CLEAR_REG_SET (bb
->global_live_at_end
);
672 /* If asked, remove notes from the blocks we'll update. */
673 if (extent
== UPDATE_LIFE_GLOBAL_RM_NOTES
)
674 count_or_remove_death_notes (blocks
, 1);
677 /* Clear log links in case we are asked to (re)compute them. */
678 if (prop_flags
& PROP_LOG_LINKS
)
679 clear_log_links (blocks
);
683 EXECUTE_IF_SET_IN_SBITMAP (blocks
, 0, i
,
685 bb
= BASIC_BLOCK (i
);
687 COPY_REG_SET (tmp
, bb
->global_live_at_end
);
688 propagate_block (bb
, tmp
, NULL
, NULL
, stabilized_prop_flags
);
690 if (extent
== UPDATE_LIFE_LOCAL
)
691 verify_local_live_at_start (tmp
, bb
);
696 FOR_EACH_BB_REVERSE (bb
)
698 COPY_REG_SET (tmp
, bb
->global_live_at_end
);
700 propagate_block (bb
, tmp
, NULL
, NULL
, stabilized_prop_flags
);
702 if (extent
== UPDATE_LIFE_LOCAL
)
703 verify_local_live_at_start (tmp
, bb
);
709 if (prop_flags
& PROP_REG_INFO
)
711 /* The only pseudos that are live at the beginning of the function
712 are those that were not set anywhere in the function. local-alloc
713 doesn't know how to handle these correctly, so mark them as not
714 local to any one basic block. */
715 EXECUTE_IF_SET_IN_REG_SET (ENTRY_BLOCK_PTR
->global_live_at_end
,
716 FIRST_PSEUDO_REGISTER
, i
,
717 { REG_BASIC_BLOCK (i
) = REG_BLOCK_GLOBAL
; });
719 /* We have a problem with any pseudoreg that lives across the setjmp.
720 ANSI says that if a user variable does not change in value between
721 the setjmp and the longjmp, then the longjmp preserves it. This
722 includes longjmp from a place where the pseudo appears dead.
723 (In principle, the value still exists if it is in scope.)
724 If the pseudo goes in a hard reg, some other value may occupy
725 that hard reg where this pseudo is dead, thus clobbering the pseudo.
726 Conclusion: such a pseudo must not go in a hard reg. */
727 EXECUTE_IF_SET_IN_REG_SET (regs_live_at_setjmp
,
728 FIRST_PSEUDO_REGISTER
, i
,
730 if (regno_reg_rtx
[i
] != 0)
732 REG_LIVE_LENGTH (i
) = -1;
733 REG_BASIC_BLOCK (i
) = REG_BLOCK_UNKNOWN
;
737 timevar_pop ((extent
== UPDATE_LIFE_LOCAL
|| blocks
)
738 ? TV_LIFE_UPDATE
: TV_LIFE
);
739 if (ndead
&& rtl_dump_file
)
740 fprintf (rtl_dump_file
, "deleted %i dead insns\n", ndead
);
744 /* Update life information in all blocks where BB_DIRTY is set. */
747 update_life_info_in_dirty_blocks (enum update_life_extent extent
, int prop_flags
)
749 sbitmap update_life_blocks
= sbitmap_alloc (last_basic_block
);
754 sbitmap_zero (update_life_blocks
);
757 if (extent
== UPDATE_LIFE_LOCAL
)
759 if (bb
->flags
& BB_DIRTY
)
761 SET_BIT (update_life_blocks
, bb
->index
);
767 /* ??? Bootstrap with -march=pentium4 fails to terminate
768 with only a partial life update. */
769 SET_BIT (update_life_blocks
, bb
->index
);
770 if (bb
->flags
& BB_DIRTY
)
776 retval
= update_life_info (update_life_blocks
, extent
, prop_flags
);
778 sbitmap_free (update_life_blocks
);
782 /* Free the variables allocated by find_basic_blocks.
784 KEEP_HEAD_END_P is nonzero if basic_block_info is not to be freed. */
787 free_basic_block_vars (int keep_head_end_p
)
789 if (! keep_head_end_p
)
791 if (basic_block_info
)
794 VARRAY_FREE (basic_block_info
);
797 last_basic_block
= 0;
799 ENTRY_BLOCK_PTR
->aux
= NULL
;
800 ENTRY_BLOCK_PTR
->global_live_at_end
= NULL
;
801 EXIT_BLOCK_PTR
->aux
= NULL
;
802 EXIT_BLOCK_PTR
->global_live_at_start
= NULL
;
806 /* Delete any insns that copy a register to itself. */
809 delete_noop_moves (rtx f ATTRIBUTE_UNUSED
)
817 for (insn
= BB_HEAD (bb
); insn
!= NEXT_INSN (BB_END (bb
)); insn
= next
)
819 next
= NEXT_INSN (insn
);
820 if (INSN_P (insn
) && noop_move_p (insn
))
824 /* If we're about to remove the first insn of a libcall
825 then move the libcall note to the next real insn and
826 update the retval note. */
827 if ((note
= find_reg_note (insn
, REG_LIBCALL
, NULL_RTX
))
828 && XEXP (note
, 0) != insn
)
830 rtx new_libcall_insn
= next_real_insn (insn
);
831 rtx retval_note
= find_reg_note (XEXP (note
, 0),
832 REG_RETVAL
, NULL_RTX
);
833 REG_NOTES (new_libcall_insn
)
834 = gen_rtx_INSN_LIST (REG_LIBCALL
, XEXP (note
, 0),
835 REG_NOTES (new_libcall_insn
));
836 XEXP (retval_note
, 0) = new_libcall_insn
;
839 delete_insn_and_edges (insn
);
844 if (nnoops
&& rtl_dump_file
)
845 fprintf (rtl_dump_file
, "deleted %i noop moves", nnoops
);
849 /* Delete any jump tables never referenced. We can't delete them at the
850 time of removing tablejump insn as they are referenced by the preceding
851 insns computing the destination, so we delay deleting and garbagecollect
852 them once life information is computed. */
854 delete_dead_jumptables (void)
857 for (insn
= get_insns (); insn
; insn
= next
)
859 next
= NEXT_INSN (insn
);
860 if (GET_CODE (insn
) == CODE_LABEL
861 && LABEL_NUSES (insn
) == LABEL_PRESERVE_P (insn
)
862 && GET_CODE (next
) == JUMP_INSN
863 && (GET_CODE (PATTERN (next
)) == ADDR_VEC
864 || GET_CODE (PATTERN (next
)) == ADDR_DIFF_VEC
))
867 fprintf (rtl_dump_file
, "Dead jumptable %i removed\n", INSN_UID (insn
));
868 delete_insn (NEXT_INSN (insn
));
870 next
= NEXT_INSN (next
);
875 /* Determine if the stack pointer is constant over the life of the function.
876 Only useful before prologues have been emitted. */
879 notice_stack_pointer_modification_1 (rtx x
, rtx pat ATTRIBUTE_UNUSED
,
880 void *data ATTRIBUTE_UNUSED
)
882 if (x
== stack_pointer_rtx
883 /* The stack pointer is only modified indirectly as the result
884 of a push until later in flow. See the comments in rtl.texi
885 regarding Embedded Side-Effects on Addresses. */
886 || (GET_CODE (x
) == MEM
887 && GET_RTX_CLASS (GET_CODE (XEXP (x
, 0))) == 'a'
888 && XEXP (XEXP (x
, 0), 0) == stack_pointer_rtx
))
889 current_function_sp_is_unchanging
= 0;
893 notice_stack_pointer_modification (rtx f
)
897 /* Assume that the stack pointer is unchanging if alloca hasn't
899 current_function_sp_is_unchanging
= !current_function_calls_alloca
;
900 if (! current_function_sp_is_unchanging
)
903 for (insn
= f
; insn
; insn
= NEXT_INSN (insn
))
907 /* Check if insn modifies the stack pointer. */
908 note_stores (PATTERN (insn
), notice_stack_pointer_modification_1
,
910 if (! current_function_sp_is_unchanging
)
916 /* Mark a register in SET. Hard registers in large modes get all
917 of their component registers set as well. */
920 mark_reg (rtx reg
, void *xset
)
922 regset set
= (regset
) xset
;
923 int regno
= REGNO (reg
);
925 if (GET_MODE (reg
) == BLKmode
)
928 SET_REGNO_REG_SET (set
, regno
);
929 if (regno
< FIRST_PSEUDO_REGISTER
)
931 int n
= HARD_REGNO_NREGS (regno
, GET_MODE (reg
));
933 SET_REGNO_REG_SET (set
, regno
+ n
);
937 /* Mark those regs which are needed at the end of the function as live
938 at the end of the last basic block. */
941 mark_regs_live_at_end (regset set
)
945 /* If exiting needs the right stack value, consider the stack pointer
946 live at the end of the function. */
947 if ((HAVE_epilogue
&& epilogue_completed
)
948 || ! EXIT_IGNORE_STACK
949 || (! FRAME_POINTER_REQUIRED
950 && ! current_function_calls_alloca
951 && flag_omit_frame_pointer
)
952 || current_function_sp_is_unchanging
)
954 SET_REGNO_REG_SET (set
, STACK_POINTER_REGNUM
);
957 /* Mark the frame pointer if needed at the end of the function. If
958 we end up eliminating it, it will be removed from the live list
959 of each basic block by reload. */
961 if (! reload_completed
|| frame_pointer_needed
)
963 SET_REGNO_REG_SET (set
, FRAME_POINTER_REGNUM
);
964 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
965 /* If they are different, also mark the hard frame pointer as live. */
966 if (! LOCAL_REGNO (HARD_FRAME_POINTER_REGNUM
))
967 SET_REGNO_REG_SET (set
, HARD_FRAME_POINTER_REGNUM
);
971 #ifndef PIC_OFFSET_TABLE_REG_CALL_CLOBBERED
972 /* Many architectures have a GP register even without flag_pic.
973 Assume the pic register is not in use, or will be handled by
974 other means, if it is not fixed. */
975 if ((unsigned) PIC_OFFSET_TABLE_REGNUM
!= INVALID_REGNUM
976 && fixed_regs
[PIC_OFFSET_TABLE_REGNUM
])
977 SET_REGNO_REG_SET (set
, PIC_OFFSET_TABLE_REGNUM
);
980 /* Mark all global registers, and all registers used by the epilogue
981 as being live at the end of the function since they may be
982 referenced by our caller. */
983 for (i
= 0; i
< FIRST_PSEUDO_REGISTER
; i
++)
984 if (global_regs
[i
] || EPILOGUE_USES (i
))
985 SET_REGNO_REG_SET (set
, i
);
987 if (HAVE_epilogue
&& epilogue_completed
)
989 /* Mark all call-saved registers that we actually used. */
990 for (i
= 0; i
< FIRST_PSEUDO_REGISTER
; i
++)
991 if (regs_ever_live
[i
] && ! LOCAL_REGNO (i
)
992 && ! TEST_HARD_REG_BIT (regs_invalidated_by_call
, i
))
993 SET_REGNO_REG_SET (set
, i
);
996 #ifdef EH_RETURN_DATA_REGNO
997 /* Mark the registers that will contain data for the handler. */
998 if (reload_completed
&& current_function_calls_eh_return
)
1001 unsigned regno
= EH_RETURN_DATA_REGNO(i
);
1002 if (regno
== INVALID_REGNUM
)
1004 SET_REGNO_REG_SET (set
, regno
);
1007 #ifdef EH_RETURN_STACKADJ_RTX
1008 if ((! HAVE_epilogue
|| ! epilogue_completed
)
1009 && current_function_calls_eh_return
)
1011 rtx tmp
= EH_RETURN_STACKADJ_RTX
;
1012 if (tmp
&& REG_P (tmp
))
1013 mark_reg (tmp
, set
);
1016 #ifdef EH_RETURN_HANDLER_RTX
1017 if ((! HAVE_epilogue
|| ! epilogue_completed
)
1018 && current_function_calls_eh_return
)
1020 rtx tmp
= EH_RETURN_HANDLER_RTX
;
1021 if (tmp
&& REG_P (tmp
))
1022 mark_reg (tmp
, set
);
1026 /* Mark function return value. */
1027 diddle_return_value (mark_reg
, set
);
1030 /* Propagate global life info around the graph of basic blocks. Begin
1031 considering blocks with their corresponding bit set in BLOCKS_IN.
1032 If BLOCKS_IN is null, consider it the universal set.
1034 BLOCKS_OUT is set for every block that was changed. */
1037 calculate_global_regs_live (sbitmap blocks_in
, sbitmap blocks_out
, int flags
)
1039 basic_block
*queue
, *qhead
, *qtail
, *qend
, bb
;
1040 regset tmp
, new_live_at_end
, invalidated_by_call
;
1041 regset_head tmp_head
, invalidated_by_call_head
;
1042 regset_head new_live_at_end_head
;
1045 /* Some passes used to forget clear aux field of basic block causing
1046 sick behavior here. */
1047 #ifdef ENABLE_CHECKING
1048 FOR_BB_BETWEEN (bb
, ENTRY_BLOCK_PTR
, NULL
, next_bb
)
1053 tmp
= INITIALIZE_REG_SET (tmp_head
);
1054 new_live_at_end
= INITIALIZE_REG_SET (new_live_at_end_head
);
1055 invalidated_by_call
= INITIALIZE_REG_SET (invalidated_by_call_head
);
1057 /* Inconveniently, this is only readily available in hard reg set form. */
1058 for (i
= 0; i
< FIRST_PSEUDO_REGISTER
; ++i
)
1059 if (TEST_HARD_REG_BIT (regs_invalidated_by_call
, i
))
1060 SET_REGNO_REG_SET (invalidated_by_call
, i
);
1062 /* Create a worklist. Allocate an extra slot for ENTRY_BLOCK, and one
1063 because the `head == tail' style test for an empty queue doesn't
1064 work with a full queue. */
1065 queue
= xmalloc ((n_basic_blocks
+ 2) * sizeof (*queue
));
1067 qhead
= qend
= queue
+ n_basic_blocks
+ 2;
1069 /* Queue the blocks set in the initial mask. Do this in reverse block
1070 number order so that we are more likely for the first round to do
1071 useful work. We use AUX non-null to flag that the block is queued. */
1075 if (TEST_BIT (blocks_in
, bb
->index
))
1090 /* We clean aux when we remove the initially-enqueued bbs, but we
1091 don't enqueue ENTRY and EXIT initially, so clean them upfront and
1093 ENTRY_BLOCK_PTR
->aux
= EXIT_BLOCK_PTR
->aux
= NULL
;
1096 sbitmap_zero (blocks_out
);
1098 /* We work through the queue until there are no more blocks. What
1099 is live at the end of this block is precisely the union of what
1100 is live at the beginning of all its successors. So, we set its
1101 GLOBAL_LIVE_AT_END field based on the GLOBAL_LIVE_AT_START field
1102 for its successors. Then, we compute GLOBAL_LIVE_AT_START for
1103 this block by walking through the instructions in this block in
1104 reverse order and updating as we go. If that changed
1105 GLOBAL_LIVE_AT_START, we add the predecessors of the block to the
1106 queue; they will now need to recalculate GLOBAL_LIVE_AT_END.
1108 We are guaranteed to terminate, because GLOBAL_LIVE_AT_START
1109 never shrinks. If a register appears in GLOBAL_LIVE_AT_START, it
1110 must either be live at the end of the block, or used within the
1111 block. In the latter case, it will certainly never disappear
1112 from GLOBAL_LIVE_AT_START. In the former case, the register
1113 could go away only if it disappeared from GLOBAL_LIVE_AT_START
1114 for one of the successor blocks. By induction, that cannot
1116 while (qhead
!= qtail
)
1118 int rescan
, changed
;
1127 /* Begin by propagating live_at_start from the successor blocks. */
1128 CLEAR_REG_SET (new_live_at_end
);
1131 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
1133 basic_block sb
= e
->dest
;
1135 /* Call-clobbered registers die across exception and
1137 /* ??? Abnormal call edges ignored for the moment, as this gets
1138 confused by sibling call edges, which crashes reg-stack. */
1139 if (e
->flags
& EDGE_EH
)
1141 bitmap_operation (tmp
, sb
->global_live_at_start
,
1142 invalidated_by_call
, BITMAP_AND_COMPL
);
1143 IOR_REG_SET (new_live_at_end
, tmp
);
1146 IOR_REG_SET (new_live_at_end
, sb
->global_live_at_start
);
1148 /* If a target saves one register in another (instead of on
1149 the stack) the save register will need to be live for EH. */
1150 if (e
->flags
& EDGE_EH
)
1151 for (i
= 0; i
< FIRST_PSEUDO_REGISTER
; i
++)
1153 SET_REGNO_REG_SET (new_live_at_end
, i
);
1157 /* This might be a noreturn function that throws. And
1158 even if it isn't, getting the unwind info right helps
1160 for (i
= 0; i
< FIRST_PSEUDO_REGISTER
; i
++)
1162 SET_REGNO_REG_SET (new_live_at_end
, i
);
1165 /* The all-important stack pointer must always be live. */
1166 SET_REGNO_REG_SET (new_live_at_end
, STACK_POINTER_REGNUM
);
1168 /* Before reload, there are a few registers that must be forced
1169 live everywhere -- which might not already be the case for
1170 blocks within infinite loops. */
1171 if (! reload_completed
)
1173 /* Any reference to any pseudo before reload is a potential
1174 reference of the frame pointer. */
1175 SET_REGNO_REG_SET (new_live_at_end
, FRAME_POINTER_REGNUM
);
1177 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
1178 /* Pseudos with argument area equivalences may require
1179 reloading via the argument pointer. */
1180 if (fixed_regs
[ARG_POINTER_REGNUM
])
1181 SET_REGNO_REG_SET (new_live_at_end
, ARG_POINTER_REGNUM
);
1184 /* Any constant, or pseudo with constant equivalences, may
1185 require reloading from memory using the pic register. */
1186 if ((unsigned) PIC_OFFSET_TABLE_REGNUM
!= INVALID_REGNUM
1187 && fixed_regs
[PIC_OFFSET_TABLE_REGNUM
])
1188 SET_REGNO_REG_SET (new_live_at_end
, PIC_OFFSET_TABLE_REGNUM
);
1191 if (bb
== ENTRY_BLOCK_PTR
)
1193 COPY_REG_SET (bb
->global_live_at_end
, new_live_at_end
);
1197 /* On our first pass through this block, we'll go ahead and continue.
1198 Recognize first pass by local_set NULL. On subsequent passes, we
1199 get to skip out early if live_at_end wouldn't have changed. */
1201 if (bb
->local_set
== NULL
)
1203 bb
->local_set
= OBSTACK_ALLOC_REG_SET (&flow_obstack
);
1204 bb
->cond_local_set
= OBSTACK_ALLOC_REG_SET (&flow_obstack
);
1209 /* If any bits were removed from live_at_end, we'll have to
1210 rescan the block. This wouldn't be necessary if we had
1211 precalculated local_live, however with PROP_SCAN_DEAD_CODE
1212 local_live is really dependent on live_at_end. */
1213 CLEAR_REG_SET (tmp
);
1214 rescan
= bitmap_operation (tmp
, bb
->global_live_at_end
,
1215 new_live_at_end
, BITMAP_AND_COMPL
);
1219 /* If any of the registers in the new live_at_end set are
1220 conditionally set in this basic block, we must rescan.
1221 This is because conditional lifetimes at the end of the
1222 block do not just take the live_at_end set into account,
1223 but also the liveness at the start of each successor
1224 block. We can miss changes in those sets if we only
1225 compare the new live_at_end against the previous one. */
1226 CLEAR_REG_SET (tmp
);
1227 rescan
= bitmap_operation (tmp
, new_live_at_end
,
1228 bb
->cond_local_set
, BITMAP_AND
);
1233 /* Find the set of changed bits. Take this opportunity
1234 to notice that this set is empty and early out. */
1235 CLEAR_REG_SET (tmp
);
1236 changed
= bitmap_operation (tmp
, bb
->global_live_at_end
,
1237 new_live_at_end
, BITMAP_XOR
);
1241 /* If any of the changed bits overlap with local_set,
1242 we'll have to rescan the block. Detect overlap by
1243 the AND with ~local_set turning off bits. */
1244 rescan
= bitmap_operation (tmp
, tmp
, bb
->local_set
,
1249 /* Let our caller know that BB changed enough to require its
1250 death notes updated. */
1252 SET_BIT (blocks_out
, bb
->index
);
1256 /* Add to live_at_start the set of all registers in
1257 new_live_at_end that aren't in the old live_at_end. */
1259 bitmap_operation (tmp
, new_live_at_end
, bb
->global_live_at_end
,
1261 COPY_REG_SET (bb
->global_live_at_end
, new_live_at_end
);
1263 changed
= bitmap_operation (bb
->global_live_at_start
,
1264 bb
->global_live_at_start
,
1271 COPY_REG_SET (bb
->global_live_at_end
, new_live_at_end
);
1273 /* Rescan the block insn by insn to turn (a copy of) live_at_end
1274 into live_at_start. */
1275 propagate_block (bb
, new_live_at_end
, bb
->local_set
,
1276 bb
->cond_local_set
, flags
);
1278 /* If live_at start didn't change, no need to go farther. */
1279 if (REG_SET_EQUAL_P (bb
->global_live_at_start
, new_live_at_end
))
1282 COPY_REG_SET (bb
->global_live_at_start
, new_live_at_end
);
1285 /* Queue all predecessors of BB so that we may re-examine
1286 their live_at_end. */
1287 for (e
= bb
->pred
; e
; e
= e
->pred_next
)
1289 basic_block pb
= e
->src
;
1290 if (pb
->aux
== NULL
)
1301 FREE_REG_SET (new_live_at_end
);
1302 FREE_REG_SET (invalidated_by_call
);
1306 EXECUTE_IF_SET_IN_SBITMAP (blocks_out
, 0, i
,
1308 basic_block bb
= BASIC_BLOCK (i
);
1309 FREE_REG_SET (bb
->local_set
);
1310 FREE_REG_SET (bb
->cond_local_set
);
1317 FREE_REG_SET (bb
->local_set
);
1318 FREE_REG_SET (bb
->cond_local_set
);
1326 /* This structure is used to pass parameters to and from the
1327 the function find_regno_partial(). It is used to pass in the
1328 register number we are looking, as well as to return any rtx
1332 unsigned regno_to_find
;
1334 } find_regno_partial_param
;
1337 /* Find the rtx for the reg numbers specified in 'data' if it is
1338 part of an expression which only uses part of the register. Return
1339 it in the structure passed in. */
1341 find_regno_partial (rtx
*ptr
, void *data
)
1343 find_regno_partial_param
*param
= (find_regno_partial_param
*)data
;
1344 unsigned reg
= param
->regno_to_find
;
1345 param
->retval
= NULL_RTX
;
1347 if (*ptr
== NULL_RTX
)
1350 switch (GET_CODE (*ptr
))
1354 case STRICT_LOW_PART
:
1355 if (GET_CODE (XEXP (*ptr
, 0)) == REG
&& REGNO (XEXP (*ptr
, 0)) == reg
)
1357 param
->retval
= XEXP (*ptr
, 0);
1363 if (GET_CODE (SUBREG_REG (*ptr
)) == REG
1364 && REGNO (SUBREG_REG (*ptr
)) == reg
)
1366 param
->retval
= SUBREG_REG (*ptr
);
1378 /* Process all immediate successors of the entry block looking for pseudo
1379 registers which are live on entry. Find all of those whose first
1380 instance is a partial register reference of some kind, and initialize
1381 them to 0 after the entry block. This will prevent bit sets within
1382 registers whose value is unknown, and may contain some kind of sticky
1383 bits we don't want. */
1386 initialize_uninitialized_subregs (void)
1390 int reg
, did_something
= 0;
1391 find_regno_partial_param param
;
1393 for (e
= ENTRY_BLOCK_PTR
->succ
; e
; e
= e
->succ_next
)
1395 basic_block bb
= e
->dest
;
1396 regset map
= bb
->global_live_at_start
;
1397 EXECUTE_IF_SET_IN_REG_SET (map
,
1398 FIRST_PSEUDO_REGISTER
, reg
,
1400 int uid
= REGNO_FIRST_UID (reg
);
1403 /* Find an insn which mentions the register we are looking for.
1404 Its preferable to have an instance of the register's rtl since
1405 there may be various flags set which we need to duplicate.
1406 If we can't find it, its probably an automatic whose initial
1407 value doesn't matter, or hopefully something we don't care about. */
1408 for (i
= get_insns (); i
&& INSN_UID (i
) != uid
; i
= NEXT_INSN (i
))
1412 /* Found the insn, now get the REG rtx, if we can. */
1413 param
.regno_to_find
= reg
;
1414 for_each_rtx (&i
, find_regno_partial
, ¶m
);
1415 if (param
.retval
!= NULL_RTX
)
1418 emit_move_insn (param
.retval
,
1419 CONST0_RTX (GET_MODE (param
.retval
)));
1420 insn
= get_insns ();
1422 insert_insn_on_edge (insn
, e
);
1430 commit_edge_insertions ();
1431 return did_something
;
1435 /* Subroutines of life analysis. */
1437 /* Allocate the permanent data structures that represent the results
1438 of life analysis. Not static since used also for stupid life analysis. */
1441 allocate_bb_life_data (void)
1445 FOR_BB_BETWEEN (bb
, ENTRY_BLOCK_PTR
, NULL
, next_bb
)
1447 bb
->global_live_at_start
= OBSTACK_ALLOC_REG_SET (&flow_obstack
);
1448 bb
->global_live_at_end
= OBSTACK_ALLOC_REG_SET (&flow_obstack
);
1451 regs_live_at_setjmp
= OBSTACK_ALLOC_REG_SET (&flow_obstack
);
1455 allocate_reg_life_data (void)
1459 max_regno
= max_reg_num ();
1461 /* Recalculate the register space, in case it has grown. Old style
1462 vector oriented regsets would set regset_{size,bytes} here also. */
1463 allocate_reg_info (max_regno
, FALSE
, FALSE
);
1465 /* Reset all the data we'll collect in propagate_block and its
1467 for (i
= 0; i
< max_regno
; i
++)
1471 REG_N_DEATHS (i
) = 0;
1472 REG_N_CALLS_CROSSED (i
) = 0;
1473 REG_N_THROWING_CALLS_CROSSED (i
) = 0;
1474 REG_LIVE_LENGTH (i
) = 0;
1476 REG_BASIC_BLOCK (i
) = REG_BLOCK_UNKNOWN
;
1480 /* Delete dead instructions for propagate_block. */
1483 propagate_block_delete_insn (rtx insn
)
1485 rtx inote
= find_reg_note (insn
, REG_LABEL
, NULL_RTX
);
1487 /* If the insn referred to a label, and that label was attached to
1488 an ADDR_VEC, it's safe to delete the ADDR_VEC. In fact, it's
1489 pretty much mandatory to delete it, because the ADDR_VEC may be
1490 referencing labels that no longer exist.
1492 INSN may reference a deleted label, particularly when a jump
1493 table has been optimized into a direct jump. There's no
1494 real good way to fix up the reference to the deleted label
1495 when the label is deleted, so we just allow it here. */
1497 if (inote
&& GET_CODE (inote
) == CODE_LABEL
)
1499 rtx label
= XEXP (inote
, 0);
1502 /* The label may be forced if it has been put in the constant
1503 pool. If that is the only use we must discard the table
1504 jump following it, but not the label itself. */
1505 if (LABEL_NUSES (label
) == 1 + LABEL_PRESERVE_P (label
)
1506 && (next
= next_nonnote_insn (label
)) != NULL
1507 && GET_CODE (next
) == JUMP_INSN
1508 && (GET_CODE (PATTERN (next
)) == ADDR_VEC
1509 || GET_CODE (PATTERN (next
)) == ADDR_DIFF_VEC
))
1511 rtx pat
= PATTERN (next
);
1512 int diff_vec_p
= GET_CODE (pat
) == ADDR_DIFF_VEC
;
1513 int len
= XVECLEN (pat
, diff_vec_p
);
1516 for (i
= 0; i
< len
; i
++)
1517 LABEL_NUSES (XEXP (XVECEXP (pat
, diff_vec_p
, i
), 0))--;
1519 delete_insn_and_edges (next
);
1524 delete_insn_and_edges (insn
);
1528 /* Delete dead libcalls for propagate_block. Return the insn
1529 before the libcall. */
1532 propagate_block_delete_libcall (rtx insn
, rtx note
)
1534 rtx first
= XEXP (note
, 0);
1535 rtx before
= PREV_INSN (first
);
1537 delete_insn_chain_and_edges (first
, insn
);
1542 /* Update the life-status of regs for one insn. Return the previous insn. */
1545 propagate_one_insn (struct propagate_block_info
*pbi
, rtx insn
)
1547 rtx prev
= PREV_INSN (insn
);
1548 int flags
= pbi
->flags
;
1549 int insn_is_dead
= 0;
1550 int libcall_is_dead
= 0;
1554 if (! INSN_P (insn
))
1557 note
= find_reg_note (insn
, REG_RETVAL
, NULL_RTX
);
1558 if (flags
& PROP_SCAN_DEAD_CODE
)
1560 insn_is_dead
= insn_dead_p (pbi
, PATTERN (insn
), 0, REG_NOTES (insn
));
1561 libcall_is_dead
= (insn_is_dead
&& note
!= 0
1562 && libcall_dead_p (pbi
, note
, insn
));
1565 /* If an instruction consists of just dead store(s) on final pass,
1567 if ((flags
& PROP_KILL_DEAD_CODE
) && insn_is_dead
)
1569 /* If we're trying to delete a prologue or epilogue instruction
1570 that isn't flagged as possibly being dead, something is wrong.
1571 But if we are keeping the stack pointer depressed, we might well
1572 be deleting insns that are used to compute the amount to update
1573 it by, so they are fine. */
1574 if (reload_completed
1575 && !(TREE_CODE (TREE_TYPE (current_function_decl
)) == FUNCTION_TYPE
1576 && (TYPE_RETURNS_STACK_DEPRESSED
1577 (TREE_TYPE (current_function_decl
))))
1578 && (((HAVE_epilogue
|| HAVE_prologue
)
1579 && prologue_epilogue_contains (insn
))
1580 || (HAVE_sibcall_epilogue
1581 && sibcall_epilogue_contains (insn
)))
1582 && find_reg_note (insn
, REG_MAYBE_DEAD
, NULL_RTX
) == 0)
1583 fatal_insn ("Attempt to delete prologue/epilogue insn:", insn
);
1585 /* Record sets. Do this even for dead instructions, since they
1586 would have killed the values if they hadn't been deleted. */
1587 mark_set_regs (pbi
, PATTERN (insn
), insn
);
1589 /* CC0 is now known to be dead. Either this insn used it,
1590 in which case it doesn't anymore, or clobbered it,
1591 so the next insn can't use it. */
1594 if (libcall_is_dead
)
1595 prev
= propagate_block_delete_libcall (insn
, note
);
1599 /* If INSN contains a RETVAL note and is dead, but the libcall
1600 as a whole is not dead, then we want to remove INSN, but
1601 not the whole libcall sequence.
1603 However, we need to also remove the dangling REG_LIBCALL
1604 note so that we do not have mis-matched LIBCALL/RETVAL
1605 notes. In theory we could find a new location for the
1606 REG_RETVAL note, but it hardly seems worth the effort.
1608 NOTE at this point will be the RETVAL note if it exists. */
1614 = find_reg_note (XEXP (note
, 0), REG_LIBCALL
, NULL_RTX
);
1615 remove_note (XEXP (note
, 0), libcall_note
);
1618 /* Similarly if INSN contains a LIBCALL note, remove the
1619 dangling REG_RETVAL note. */
1620 note
= find_reg_note (insn
, REG_LIBCALL
, NULL_RTX
);
1626 = find_reg_note (XEXP (note
, 0), REG_RETVAL
, NULL_RTX
);
1627 remove_note (XEXP (note
, 0), retval_note
);
1630 /* Now delete INSN. */
1631 propagate_block_delete_insn (insn
);
1637 /* See if this is an increment or decrement that can be merged into
1638 a following memory address. */
1641 rtx x
= single_set (insn
);
1643 /* Does this instruction increment or decrement a register? */
1644 if ((flags
& PROP_AUTOINC
)
1646 && GET_CODE (SET_DEST (x
)) == REG
1647 && (GET_CODE (SET_SRC (x
)) == PLUS
1648 || GET_CODE (SET_SRC (x
)) == MINUS
)
1649 && XEXP (SET_SRC (x
), 0) == SET_DEST (x
)
1650 && GET_CODE (XEXP (SET_SRC (x
), 1)) == CONST_INT
1651 /* Ok, look for a following memory ref we can combine with.
1652 If one is found, change the memory ref to a PRE_INC
1653 or PRE_DEC, cancel this insn, and return 1.
1654 Return 0 if nothing has been done. */
1655 && try_pre_increment_1 (pbi
, insn
))
1658 #endif /* AUTO_INC_DEC */
1660 CLEAR_REG_SET (pbi
->new_set
);
1662 /* If this is not the final pass, and this insn is copying the value of
1663 a library call and it's dead, don't scan the insns that perform the
1664 library call, so that the call's arguments are not marked live. */
1665 if (libcall_is_dead
)
1667 /* Record the death of the dest reg. */
1668 mark_set_regs (pbi
, PATTERN (insn
), insn
);
1670 insn
= XEXP (note
, 0);
1671 return PREV_INSN (insn
);
1673 else if (GET_CODE (PATTERN (insn
)) == SET
1674 && SET_DEST (PATTERN (insn
)) == stack_pointer_rtx
1675 && GET_CODE (SET_SRC (PATTERN (insn
))) == PLUS
1676 && XEXP (SET_SRC (PATTERN (insn
)), 0) == stack_pointer_rtx
1677 && GET_CODE (XEXP (SET_SRC (PATTERN (insn
)), 1)) == CONST_INT
)
1678 /* We have an insn to pop a constant amount off the stack.
1679 (Such insns use PLUS regardless of the direction of the stack,
1680 and any insn to adjust the stack by a constant is always a pop.)
1681 These insns, if not dead stores, have no effect on life, though
1682 they do have an effect on the memory stores we are tracking. */
1683 invalidate_mems_from_set (pbi
, stack_pointer_rtx
);
1687 /* Any regs live at the time of a call instruction must not go
1688 in a register clobbered by calls. Find all regs now live and
1689 record this for them. */
1691 if (GET_CODE (insn
) == CALL_INSN
&& (flags
& PROP_REG_INFO
))
1693 EXECUTE_IF_SET_IN_REG_SET (pbi
->reg_live
, 0, i
,
1694 { REG_N_CALLS_CROSSED (i
)++; });
1695 if (can_throw_internal (insn
))
1696 EXECUTE_IF_SET_IN_REG_SET (pbi
->reg_live
, 0, i
,
1697 { REG_N_THROWING_CALLS_CROSSED (i
)++; });
1700 /* Record sets. Do this even for dead instructions, since they
1701 would have killed the values if they hadn't been deleted. */
1702 mark_set_regs (pbi
, PATTERN (insn
), insn
);
1704 if (GET_CODE (insn
) == CALL_INSN
)
1712 if (GET_CODE (PATTERN (insn
)) == COND_EXEC
)
1713 cond
= COND_EXEC_TEST (PATTERN (insn
));
1715 /* Non-constant calls clobber memory, constant calls do not
1716 clobber memory, though they may clobber outgoing arguments
1718 if (! CONST_OR_PURE_CALL_P (insn
))
1720 free_EXPR_LIST_list (&pbi
->mem_set_list
);
1721 pbi
->mem_set_list_len
= 0;
1724 invalidate_mems_from_set (pbi
, stack_pointer_rtx
);
1726 /* There may be extra registers to be clobbered. */
1727 for (note
= CALL_INSN_FUNCTION_USAGE (insn
);
1729 note
= XEXP (note
, 1))
1730 if (GET_CODE (XEXP (note
, 0)) == CLOBBER
)
1731 mark_set_1 (pbi
, CLOBBER
, XEXP (XEXP (note
, 0), 0),
1732 cond
, insn
, pbi
->flags
);
1734 /* Calls change all call-used and global registers; sibcalls do not
1735 clobber anything that must be preserved at end-of-function,
1736 except for return values. */
1738 sibcall_p
= SIBLING_CALL_P (insn
);
1739 live_at_end
= EXIT_BLOCK_PTR
->global_live_at_start
;
1740 for (i
= 0; i
< FIRST_PSEUDO_REGISTER
; i
++)
1741 if (TEST_HARD_REG_BIT (regs_invalidated_by_call
, i
)
1743 && REGNO_REG_SET_P (live_at_end
, i
)
1744 && ! refers_to_regno_p (i
, i
+1,
1745 current_function_return_rtx
,
1748 enum rtx_code code
= global_regs
[i
] ? SET
: CLOBBER
;
1749 /* We do not want REG_UNUSED notes for these registers. */
1750 mark_set_1 (pbi
, code
, regno_reg_rtx
[i
], cond
, insn
,
1751 pbi
->flags
& ~(PROP_DEATH_NOTES
| PROP_REG_INFO
));
1755 /* If an insn doesn't use CC0, it becomes dead since we assume
1756 that every insn clobbers it. So show it dead here;
1757 mark_used_regs will set it live if it is referenced. */
1762 mark_used_regs (pbi
, PATTERN (insn
), NULL_RTX
, insn
);
1763 if ((flags
& PROP_EQUAL_NOTES
)
1764 && ((note
= find_reg_note (insn
, REG_EQUAL
, NULL_RTX
))
1765 || (note
= find_reg_note (insn
, REG_EQUIV
, NULL_RTX
))))
1766 mark_used_regs (pbi
, XEXP (note
, 0), NULL_RTX
, insn
);
1768 /* Sometimes we may have inserted something before INSN (such as a move)
1769 when we make an auto-inc. So ensure we will scan those insns. */
1771 prev
= PREV_INSN (insn
);
1774 if (! insn_is_dead
&& GET_CODE (insn
) == CALL_INSN
)
1780 if (GET_CODE (PATTERN (insn
)) == COND_EXEC
)
1781 cond
= COND_EXEC_TEST (PATTERN (insn
));
1783 /* Calls use their arguments, and may clobber memory which
1784 address involves some register. */
1785 for (note
= CALL_INSN_FUNCTION_USAGE (insn
);
1787 note
= XEXP (note
, 1))
1788 /* We find USE or CLOBBER entities in a FUNCTION_USAGE list: both
1789 of which mark_used_regs knows how to handle. */
1790 mark_used_regs (pbi
, XEXP (XEXP (note
, 0), 0), cond
, insn
);
1792 /* The stack ptr is used (honorarily) by a CALL insn. */
1793 SET_REGNO_REG_SET (pbi
->reg_live
, STACK_POINTER_REGNUM
);
1795 /* Calls may also reference any of the global registers,
1796 so they are made live. */
1797 for (i
= 0; i
< FIRST_PSEUDO_REGISTER
; i
++)
1799 mark_used_reg (pbi
, regno_reg_rtx
[i
], cond
, insn
);
1803 /* On final pass, update counts of how many insns in which each reg
1805 if (flags
& PROP_REG_INFO
)
1806 EXECUTE_IF_SET_IN_REG_SET (pbi
->reg_live
, 0, i
,
1807 { REG_LIVE_LENGTH (i
)++; });
1812 /* Initialize a propagate_block_info struct for public consumption.
1813 Note that the structure itself is opaque to this file, but that
1814 the user can use the regsets provided here. */
1816 struct propagate_block_info
*
1817 init_propagate_block_info (basic_block bb
, regset live
, regset local_set
,
1818 regset cond_local_set
, int flags
)
1820 struct propagate_block_info
*pbi
= xmalloc (sizeof (*pbi
));
1823 pbi
->reg_live
= live
;
1824 pbi
->mem_set_list
= NULL_RTX
;
1825 pbi
->mem_set_list_len
= 0;
1826 pbi
->local_set
= local_set
;
1827 pbi
->cond_local_set
= cond_local_set
;
1831 if (flags
& (PROP_LOG_LINKS
| PROP_AUTOINC
))
1832 pbi
->reg_next_use
= xcalloc (max_reg_num (), sizeof (rtx
));
1834 pbi
->reg_next_use
= NULL
;
1836 pbi
->new_set
= BITMAP_XMALLOC ();
1838 #ifdef HAVE_conditional_execution
1839 pbi
->reg_cond_dead
= splay_tree_new (splay_tree_compare_ints
, NULL
,
1840 free_reg_cond_life_info
);
1841 pbi
->reg_cond_reg
= BITMAP_XMALLOC ();
1843 /* If this block ends in a conditional branch, for each register
1844 live from one side of the branch and not the other, record the
1845 register as conditionally dead. */
1846 if (GET_CODE (BB_END (bb
)) == JUMP_INSN
1847 && any_condjump_p (BB_END (bb
)))
1849 regset_head diff_head
;
1850 regset diff
= INITIALIZE_REG_SET (diff_head
);
1851 basic_block bb_true
, bb_false
;
1854 /* Identify the successor blocks. */
1855 bb_true
= bb
->succ
->dest
;
1856 if (bb
->succ
->succ_next
!= NULL
)
1858 bb_false
= bb
->succ
->succ_next
->dest
;
1860 if (bb
->succ
->flags
& EDGE_FALLTHRU
)
1862 basic_block t
= bb_false
;
1866 else if (! (bb
->succ
->succ_next
->flags
& EDGE_FALLTHRU
))
1871 /* This can happen with a conditional jump to the next insn. */
1872 if (JUMP_LABEL (BB_END (bb
)) != BB_HEAD (bb_true
))
1875 /* Simplest way to do nothing. */
1879 /* Compute which register lead different lives in the successors. */
1880 if (bitmap_operation (diff
, bb_true
->global_live_at_start
,
1881 bb_false
->global_live_at_start
, BITMAP_XOR
))
1883 /* Extract the condition from the branch. */
1884 rtx set_src
= SET_SRC (pc_set (BB_END (bb
)));
1885 rtx cond_true
= XEXP (set_src
, 0);
1886 rtx reg
= XEXP (cond_true
, 0);
1888 if (GET_CODE (reg
) == SUBREG
)
1889 reg
= SUBREG_REG (reg
);
1891 /* We can only track conditional lifetimes if the condition is
1892 in the form of a comparison of a register against zero.
1893 If the condition is more complex than that, then it is safe
1894 not to record any information. */
1895 if (GET_CODE (reg
) == REG
1896 && XEXP (cond_true
, 1) == const0_rtx
)
1899 = gen_rtx_fmt_ee (reverse_condition (GET_CODE (cond_true
)),
1900 GET_MODE (cond_true
), XEXP (cond_true
, 0),
1901 XEXP (cond_true
, 1));
1902 if (GET_CODE (XEXP (set_src
, 1)) == PC
)
1905 cond_false
= cond_true
;
1909 SET_REGNO_REG_SET (pbi
->reg_cond_reg
, REGNO (reg
));
1911 /* For each such register, mark it conditionally dead. */
1912 EXECUTE_IF_SET_IN_REG_SET
1915 struct reg_cond_life_info
*rcli
;
1918 rcli
= xmalloc (sizeof (*rcli
));
1920 if (REGNO_REG_SET_P (bb_true
->global_live_at_start
, i
))
1924 rcli
->condition
= cond
;
1925 rcli
->stores
= const0_rtx
;
1926 rcli
->orig_condition
= cond
;
1928 splay_tree_insert (pbi
->reg_cond_dead
, i
,
1929 (splay_tree_value
) rcli
);
1934 FREE_REG_SET (diff
);
1938 /* If this block has no successors, any stores to the frame that aren't
1939 used later in the block are dead. So make a pass over the block
1940 recording any such that are made and show them dead at the end. We do
1941 a very conservative and simple job here. */
1943 && ! (TREE_CODE (TREE_TYPE (current_function_decl
)) == FUNCTION_TYPE
1944 && (TYPE_RETURNS_STACK_DEPRESSED
1945 (TREE_TYPE (current_function_decl
))))
1946 && (flags
& PROP_SCAN_DEAD_STORES
)
1947 && (bb
->succ
== NULL
1948 || (bb
->succ
->succ_next
== NULL
1949 && bb
->succ
->dest
== EXIT_BLOCK_PTR
1950 && ! current_function_calls_eh_return
)))
1953 for (insn
= BB_END (bb
); insn
!= BB_HEAD (bb
); insn
= PREV_INSN (insn
))
1954 if (GET_CODE (insn
) == INSN
1955 && (set
= single_set (insn
))
1956 && GET_CODE (SET_DEST (set
)) == MEM
)
1958 rtx mem
= SET_DEST (set
);
1959 rtx canon_mem
= canon_rtx (mem
);
1961 if (XEXP (canon_mem
, 0) == frame_pointer_rtx
1962 || (GET_CODE (XEXP (canon_mem
, 0)) == PLUS
1963 && XEXP (XEXP (canon_mem
, 0), 0) == frame_pointer_rtx
1964 && GET_CODE (XEXP (XEXP (canon_mem
, 0), 1)) == CONST_INT
))
1965 add_to_mem_set_list (pbi
, canon_mem
);
1972 /* Release a propagate_block_info struct. */
1975 free_propagate_block_info (struct propagate_block_info
*pbi
)
1977 free_EXPR_LIST_list (&pbi
->mem_set_list
);
1979 BITMAP_XFREE (pbi
->new_set
);
1981 #ifdef HAVE_conditional_execution
1982 splay_tree_delete (pbi
->reg_cond_dead
);
1983 BITMAP_XFREE (pbi
->reg_cond_reg
);
1986 if (pbi
->reg_next_use
)
1987 free (pbi
->reg_next_use
);
1992 /* Compute the registers live at the beginning of a basic block BB from
1993 those live at the end.
1995 When called, REG_LIVE contains those live at the end. On return, it
1996 contains those live at the beginning.
1998 LOCAL_SET, if non-null, will be set with all registers killed
1999 unconditionally by this basic block.
2000 Likewise, COND_LOCAL_SET, if non-null, will be set with all registers
2001 killed conditionally by this basic block. If there is any unconditional
2002 set of a register, then the corresponding bit will be set in LOCAL_SET
2003 and cleared in COND_LOCAL_SET.
2004 It is valid for LOCAL_SET and COND_LOCAL_SET to be the same set. In this
2005 case, the resulting set will be equal to the union of the two sets that
2006 would otherwise be computed.
2008 Return nonzero if an INSN is deleted (i.e. by dead code removal). */
2011 propagate_block (basic_block bb
, regset live
, regset local_set
,
2012 regset cond_local_set
, int flags
)
2014 struct propagate_block_info
*pbi
;
2018 pbi
= init_propagate_block_info (bb
, live
, local_set
, cond_local_set
, flags
);
2020 if (flags
& PROP_REG_INFO
)
2024 /* Process the regs live at the end of the block.
2025 Mark them as not local to any one basic block. */
2026 EXECUTE_IF_SET_IN_REG_SET (live
, 0, i
,
2027 { REG_BASIC_BLOCK (i
) = REG_BLOCK_GLOBAL
; });
2030 /* Scan the block an insn at a time from end to beginning. */
2033 for (insn
= BB_END (bb
); ; insn
= prev
)
2035 /* If this is a call to `setjmp' et al, warn if any
2036 non-volatile datum is live. */
2037 if ((flags
& PROP_REG_INFO
)
2038 && GET_CODE (insn
) == CALL_INSN
2039 && find_reg_note (insn
, REG_SETJMP
, NULL
))
2040 IOR_REG_SET (regs_live_at_setjmp
, pbi
->reg_live
);
2042 prev
= propagate_one_insn (pbi
, insn
);
2044 changed
|= insn
!= get_insns ();
2046 changed
|= NEXT_INSN (prev
) != insn
;
2048 if (insn
== BB_HEAD (bb
))
2052 free_propagate_block_info (pbi
);
2057 /* Return 1 if X (the body of an insn, or part of it) is just dead stores
2058 (SET expressions whose destinations are registers dead after the insn).
2059 NEEDED is the regset that says which regs are alive after the insn.
2061 Unless CALL_OK is nonzero, an insn is needed if it contains a CALL.
2063 If X is the entire body of an insn, NOTES contains the reg notes
2064 pertaining to the insn. */
2067 insn_dead_p (struct propagate_block_info
*pbi
, rtx x
, int call_ok
,
2068 rtx notes ATTRIBUTE_UNUSED
)
2070 enum rtx_code code
= GET_CODE (x
);
2072 /* Don't eliminate insns that may trap. */
2073 if (flag_non_call_exceptions
&& may_trap_p (x
))
2077 /* As flow is invoked after combine, we must take existing AUTO_INC
2078 expressions into account. */
2079 for (; notes
; notes
= XEXP (notes
, 1))
2081 if (REG_NOTE_KIND (notes
) == REG_INC
)
2083 int regno
= REGNO (XEXP (notes
, 0));
2085 /* Don't delete insns to set global regs. */
2086 if ((regno
< FIRST_PSEUDO_REGISTER
&& global_regs
[regno
])
2087 || REGNO_REG_SET_P (pbi
->reg_live
, regno
))
2093 /* If setting something that's a reg or part of one,
2094 see if that register's altered value will be live. */
2098 rtx r
= SET_DEST (x
);
2101 if (GET_CODE (r
) == CC0
)
2102 return ! pbi
->cc0_live
;
2105 /* A SET that is a subroutine call cannot be dead. */
2106 if (GET_CODE (SET_SRC (x
)) == CALL
)
2112 /* Don't eliminate loads from volatile memory or volatile asms. */
2113 else if (volatile_refs_p (SET_SRC (x
)))
2116 if (GET_CODE (r
) == MEM
)
2120 if (MEM_VOLATILE_P (r
) || GET_MODE (r
) == BLKmode
)
2123 canon_r
= canon_rtx (r
);
2125 /* Walk the set of memory locations we are currently tracking
2126 and see if one is an identical match to this memory location.
2127 If so, this memory write is dead (remember, we're walking
2128 backwards from the end of the block to the start). Since
2129 rtx_equal_p does not check the alias set or flags, we also
2130 must have the potential for them to conflict (anti_dependence). */
2131 for (temp
= pbi
->mem_set_list
; temp
!= 0; temp
= XEXP (temp
, 1))
2132 if (unchanging_anti_dependence (r
, XEXP (temp
, 0)))
2134 rtx mem
= XEXP (temp
, 0);
2136 if (rtx_equal_p (XEXP (canon_r
, 0), XEXP (mem
, 0))
2137 && (GET_MODE_SIZE (GET_MODE (canon_r
))
2138 <= GET_MODE_SIZE (GET_MODE (mem
))))
2142 /* Check if memory reference matches an auto increment. Only
2143 post increment/decrement or modify are valid. */
2144 if (GET_MODE (mem
) == GET_MODE (r
)
2145 && (GET_CODE (XEXP (mem
, 0)) == POST_DEC
2146 || GET_CODE (XEXP (mem
, 0)) == POST_INC
2147 || GET_CODE (XEXP (mem
, 0)) == POST_MODIFY
)
2148 && GET_MODE (XEXP (mem
, 0)) == GET_MODE (r
)
2149 && rtx_equal_p (XEXP (XEXP (mem
, 0), 0), XEXP (r
, 0)))
2156 while (GET_CODE (r
) == SUBREG
2157 || GET_CODE (r
) == STRICT_LOW_PART
2158 || GET_CODE (r
) == ZERO_EXTRACT
)
2161 if (GET_CODE (r
) == REG
)
2163 int regno
= REGNO (r
);
2166 if (REGNO_REG_SET_P (pbi
->reg_live
, regno
))
2169 /* If this is a hard register, verify that subsequent
2170 words are not needed. */
2171 if (regno
< FIRST_PSEUDO_REGISTER
)
2173 int n
= HARD_REGNO_NREGS (regno
, GET_MODE (r
));
2176 if (REGNO_REG_SET_P (pbi
->reg_live
, regno
+n
))
2180 /* Don't delete insns to set global regs. */
2181 if (regno
< FIRST_PSEUDO_REGISTER
&& global_regs
[regno
])
2184 /* Make sure insns to set the stack pointer aren't deleted. */
2185 if (regno
== STACK_POINTER_REGNUM
)
2188 /* ??? These bits might be redundant with the force live bits
2189 in calculate_global_regs_live. We would delete from
2190 sequential sets; whether this actually affects real code
2191 for anything but the stack pointer I don't know. */
2192 /* Make sure insns to set the frame pointer aren't deleted. */
2193 if (regno
== FRAME_POINTER_REGNUM
2194 && (! reload_completed
|| frame_pointer_needed
))
2196 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
2197 if (regno
== HARD_FRAME_POINTER_REGNUM
2198 && (! reload_completed
|| frame_pointer_needed
))
2202 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
2203 /* Make sure insns to set arg pointer are never deleted
2204 (if the arg pointer isn't fixed, there will be a USE
2205 for it, so we can treat it normally). */
2206 if (regno
== ARG_POINTER_REGNUM
&& fixed_regs
[regno
])
2210 /* Otherwise, the set is dead. */
2216 /* If performing several activities, insn is dead if each activity
2217 is individually dead. Also, CLOBBERs and USEs can be ignored; a
2218 CLOBBER or USE that's inside a PARALLEL doesn't make the insn
2220 else if (code
== PARALLEL
)
2222 int i
= XVECLEN (x
, 0);
2224 for (i
--; i
>= 0; i
--)
2225 if (GET_CODE (XVECEXP (x
, 0, i
)) != CLOBBER
2226 && GET_CODE (XVECEXP (x
, 0, i
)) != USE
2227 && ! insn_dead_p (pbi
, XVECEXP (x
, 0, i
), call_ok
, NULL_RTX
))
2233 /* A CLOBBER of a pseudo-register that is dead serves no purpose. That
2234 is not necessarily true for hard registers until after reload. */
2235 else if (code
== CLOBBER
)
2237 if (GET_CODE (XEXP (x
, 0)) == REG
2238 && (REGNO (XEXP (x
, 0)) >= FIRST_PSEUDO_REGISTER
2239 || reload_completed
)
2240 && ! REGNO_REG_SET_P (pbi
->reg_live
, REGNO (XEXP (x
, 0))))
2244 /* ??? A base USE is a historical relic. It ought not be needed anymore.
2245 Instances where it is still used are either (1) temporary and the USE
2246 escaped the pass, (2) cruft and the USE need not be emitted anymore,
2247 or (3) hiding bugs elsewhere that are not properly representing data
2253 /* If INSN is the last insn in a libcall, and assuming INSN is dead,
2254 return 1 if the entire library call is dead.
2255 This is true if INSN copies a register (hard or pseudo)
2256 and if the hard return reg of the call insn is dead.
2257 (The caller should have tested the destination of the SET inside
2258 INSN already for death.)
2260 If this insn doesn't just copy a register, then we don't
2261 have an ordinary libcall. In that case, cse could not have
2262 managed to substitute the source for the dest later on,
2263 so we can assume the libcall is dead.
2265 PBI is the block info giving pseudoregs live before this insn.
2266 NOTE is the REG_RETVAL note of the insn. */
2269 libcall_dead_p (struct propagate_block_info
*pbi
, rtx note
, rtx insn
)
2271 rtx x
= single_set (insn
);
2275 rtx r
= SET_SRC (x
);
2277 if (GET_CODE (r
) == REG
|| GET_CODE (r
) == SUBREG
)
2279 rtx call
= XEXP (note
, 0);
2283 /* Find the call insn. */
2284 while (call
!= insn
&& GET_CODE (call
) != CALL_INSN
)
2285 call
= NEXT_INSN (call
);
2287 /* If there is none, do nothing special,
2288 since ordinary death handling can understand these insns. */
2292 /* See if the hard reg holding the value is dead.
2293 If this is a PARALLEL, find the call within it. */
2294 call_pat
= PATTERN (call
);
2295 if (GET_CODE (call_pat
) == PARALLEL
)
2297 for (i
= XVECLEN (call_pat
, 0) - 1; i
>= 0; i
--)
2298 if (GET_CODE (XVECEXP (call_pat
, 0, i
)) == SET
2299 && GET_CODE (SET_SRC (XVECEXP (call_pat
, 0, i
))) == CALL
)
2302 /* This may be a library call that is returning a value
2303 via invisible pointer. Do nothing special, since
2304 ordinary death handling can understand these insns. */
2308 call_pat
= XVECEXP (call_pat
, 0, i
);
2311 if (! insn_dead_p (pbi
, call_pat
, 1, REG_NOTES (call
)))
2314 while ((insn
= PREV_INSN (insn
)) != call
)
2316 if (! INSN_P (insn
))
2318 if (! insn_dead_p (pbi
, PATTERN (insn
), 0, REG_NOTES (insn
)))
2327 /* Return 1 if register REGNO was used before it was set, i.e. if it is
2328 live at function entry. Don't count global register variables, variables
2329 in registers that can be used for function arg passing, or variables in
2330 fixed hard registers. */
2333 regno_uninitialized (unsigned int regno
)
2335 if (n_basic_blocks
== 0
2336 || (regno
< FIRST_PSEUDO_REGISTER
2337 && (global_regs
[regno
]
2338 || fixed_regs
[regno
]
2339 || FUNCTION_ARG_REGNO_P (regno
))))
2342 return REGNO_REG_SET_P (ENTRY_BLOCK_PTR
->global_live_at_end
, regno
);
2345 /* 1 if register REGNO was alive at a place where `setjmp' was called
2346 and was set more than once or is an argument.
2347 Such regs may be clobbered by `longjmp'. */
2350 regno_clobbered_at_setjmp (int regno
)
2352 if (n_basic_blocks
== 0)
2355 return ((REG_N_SETS (regno
) > 1
2356 || REGNO_REG_SET_P (ENTRY_BLOCK_PTR
->global_live_at_end
, regno
))
2357 && REGNO_REG_SET_P (regs_live_at_setjmp
, regno
));
2360 /* Add MEM to PBI->MEM_SET_LIST. MEM should be canonical. Respect the
2361 maximal list size; look for overlaps in mode and select the largest. */
2363 add_to_mem_set_list (struct propagate_block_info
*pbi
, rtx mem
)
2367 /* We don't know how large a BLKmode store is, so we must not
2368 take them into consideration. */
2369 if (GET_MODE (mem
) == BLKmode
)
2372 for (i
= pbi
->mem_set_list
; i
; i
= XEXP (i
, 1))
2374 rtx e
= XEXP (i
, 0);
2375 if (rtx_equal_p (XEXP (mem
, 0), XEXP (e
, 0)))
2377 if (GET_MODE_SIZE (GET_MODE (mem
)) > GET_MODE_SIZE (GET_MODE (e
)))
2380 /* If we must store a copy of the mem, we can just modify
2381 the mode of the stored copy. */
2382 if (pbi
->flags
& PROP_AUTOINC
)
2383 PUT_MODE (e
, GET_MODE (mem
));
2392 if (pbi
->mem_set_list_len
< MAX_MEM_SET_LIST_LEN
)
2395 /* Store a copy of mem, otherwise the address may be
2396 scrogged by find_auto_inc. */
2397 if (pbi
->flags
& PROP_AUTOINC
)
2398 mem
= shallow_copy_rtx (mem
);
2400 pbi
->mem_set_list
= alloc_EXPR_LIST (0, mem
, pbi
->mem_set_list
);
2401 pbi
->mem_set_list_len
++;
2405 /* INSN references memory, possibly using autoincrement addressing modes.
2406 Find any entries on the mem_set_list that need to be invalidated due
2407 to an address change. */
2410 invalidate_mems_from_autoinc (rtx
*px
, void *data
)
2413 struct propagate_block_info
*pbi
= data
;
2415 if (GET_RTX_CLASS (GET_CODE (x
)) == 'a')
2417 invalidate_mems_from_set (pbi
, XEXP (x
, 0));
2424 /* EXP is a REG. Remove any dependent entries from pbi->mem_set_list. */
2427 invalidate_mems_from_set (struct propagate_block_info
*pbi
, rtx exp
)
2429 rtx temp
= pbi
->mem_set_list
;
2430 rtx prev
= NULL_RTX
;
2435 next
= XEXP (temp
, 1);
2436 if (reg_overlap_mentioned_p (exp
, XEXP (temp
, 0)))
2438 /* Splice this entry out of the list. */
2440 XEXP (prev
, 1) = next
;
2442 pbi
->mem_set_list
= next
;
2443 free_EXPR_LIST_node (temp
);
2444 pbi
->mem_set_list_len
--;
2452 /* Process the registers that are set within X. Their bits are set to
2453 1 in the regset DEAD, because they are dead prior to this insn.
2455 If INSN is nonzero, it is the insn being processed.
2457 FLAGS is the set of operations to perform. */
2460 mark_set_regs (struct propagate_block_info
*pbi
, rtx x
, rtx insn
)
2462 rtx cond
= NULL_RTX
;
2465 int flags
= pbi
->flags
;
2468 for (link
= REG_NOTES (insn
); link
; link
= XEXP (link
, 1))
2470 if (REG_NOTE_KIND (link
) == REG_INC
)
2471 mark_set_1 (pbi
, SET
, XEXP (link
, 0),
2472 (GET_CODE (x
) == COND_EXEC
2473 ? COND_EXEC_TEST (x
) : NULL_RTX
),
2477 switch (code
= GET_CODE (x
))
2480 if (GET_CODE (XEXP (x
, 1)) == ASM_OPERANDS
)
2481 flags
|= PROP_ASM_SCAN
;
2484 mark_set_1 (pbi
, code
, SET_DEST (x
), cond
, insn
, flags
);
2488 cond
= COND_EXEC_TEST (x
);
2489 x
= COND_EXEC_CODE (x
);
2496 /* We must scan forwards. If we have an asm, we need to set
2497 the PROP_ASM_SCAN flag before scanning the clobbers. */
2498 for (i
= 0; i
< XVECLEN (x
, 0); i
++)
2500 rtx sub
= XVECEXP (x
, 0, i
);
2501 switch (code
= GET_CODE (sub
))
2504 if (cond
!= NULL_RTX
)
2507 cond
= COND_EXEC_TEST (sub
);
2508 sub
= COND_EXEC_CODE (sub
);
2509 if (GET_CODE (sub
) == SET
)
2511 if (GET_CODE (sub
) == CLOBBER
)
2517 if (GET_CODE (XEXP (sub
, 1)) == ASM_OPERANDS
)
2518 flags
|= PROP_ASM_SCAN
;
2522 mark_set_1 (pbi
, code
, SET_DEST (sub
), cond
, insn
, flags
);
2526 flags
|= PROP_ASM_SCAN
;
2541 /* Process a single set, which appears in INSN. REG (which may not
2542 actually be a REG, it may also be a SUBREG, PARALLEL, etc.) is
2543 being set using the CODE (which may be SET, CLOBBER, or COND_EXEC).
2544 If the set is conditional (because it appear in a COND_EXEC), COND
2545 will be the condition. */
2548 mark_set_1 (struct propagate_block_info
*pbi
, enum rtx_code code
, rtx reg
, rtx cond
, rtx insn
, int flags
)
2550 int regno_first
= -1, regno_last
= -1;
2551 unsigned long not_dead
= 0;
2554 /* Modifying just one hardware register of a multi-reg value or just a
2555 byte field of a register does not mean the value from before this insn
2556 is now dead. Of course, if it was dead after it's unused now. */
2558 switch (GET_CODE (reg
))
2561 /* Some targets place small structures in registers for return values of
2562 functions. We have to detect this case specially here to get correct
2563 flow information. */
2564 for (i
= XVECLEN (reg
, 0) - 1; i
>= 0; i
--)
2565 if (XEXP (XVECEXP (reg
, 0, i
), 0) != 0)
2566 mark_set_1 (pbi
, code
, XEXP (XVECEXP (reg
, 0, i
), 0), cond
, insn
,
2572 case STRICT_LOW_PART
:
2573 /* ??? Assumes STRICT_LOW_PART not used on multi-word registers. */
2575 reg
= XEXP (reg
, 0);
2576 while (GET_CODE (reg
) == SUBREG
2577 || GET_CODE (reg
) == ZERO_EXTRACT
2578 || GET_CODE (reg
) == SIGN_EXTRACT
2579 || GET_CODE (reg
) == STRICT_LOW_PART
);
2580 if (GET_CODE (reg
) == MEM
)
2582 not_dead
= (unsigned long) REGNO_REG_SET_P (pbi
->reg_live
, REGNO (reg
));
2586 regno_last
= regno_first
= REGNO (reg
);
2587 if (regno_first
< FIRST_PSEUDO_REGISTER
)
2588 regno_last
+= HARD_REGNO_NREGS (regno_first
, GET_MODE (reg
)) - 1;
2592 if (GET_CODE (SUBREG_REG (reg
)) == REG
)
2594 enum machine_mode outer_mode
= GET_MODE (reg
);
2595 enum machine_mode inner_mode
= GET_MODE (SUBREG_REG (reg
));
2597 /* Identify the range of registers affected. This is moderately
2598 tricky for hard registers. See alter_subreg. */
2600 regno_last
= regno_first
= REGNO (SUBREG_REG (reg
));
2601 if (regno_first
< FIRST_PSEUDO_REGISTER
)
2603 regno_first
+= subreg_regno_offset (regno_first
, inner_mode
,
2606 regno_last
= (regno_first
2607 + HARD_REGNO_NREGS (regno_first
, outer_mode
) - 1);
2609 /* Since we've just adjusted the register number ranges, make
2610 sure REG matches. Otherwise some_was_live will be clear
2611 when it shouldn't have been, and we'll create incorrect
2612 REG_UNUSED notes. */
2613 reg
= gen_rtx_REG (outer_mode
, regno_first
);
2617 /* If the number of words in the subreg is less than the number
2618 of words in the full register, we have a well-defined partial
2619 set. Otherwise the high bits are undefined.
2621 This is only really applicable to pseudos, since we just took
2622 care of multi-word hard registers. */
2623 if (((GET_MODE_SIZE (outer_mode
)
2624 + UNITS_PER_WORD
- 1) / UNITS_PER_WORD
)
2625 < ((GET_MODE_SIZE (inner_mode
)
2626 + UNITS_PER_WORD
- 1) / UNITS_PER_WORD
))
2627 not_dead
= (unsigned long) REGNO_REG_SET_P (pbi
->reg_live
,
2630 reg
= SUBREG_REG (reg
);
2634 reg
= SUBREG_REG (reg
);
2641 /* If this set is a MEM, then it kills any aliased writes.
2642 If this set is a REG, then it kills any MEMs which use the reg. */
2643 if (optimize
&& (flags
& PROP_SCAN_DEAD_STORES
))
2645 if (GET_CODE (reg
) == REG
)
2646 invalidate_mems_from_set (pbi
, reg
);
2648 /* If the memory reference had embedded side effects (autoincrement
2649 address modes. Then we may need to kill some entries on the
2651 if (insn
&& GET_CODE (reg
) == MEM
)
2652 for_each_rtx (&PATTERN (insn
), invalidate_mems_from_autoinc
, pbi
);
2654 if (GET_CODE (reg
) == MEM
&& ! side_effects_p (reg
)
2655 /* ??? With more effort we could track conditional memory life. */
2657 add_to_mem_set_list (pbi
, canon_rtx (reg
));
2660 if (GET_CODE (reg
) == REG
2661 && ! (regno_first
== FRAME_POINTER_REGNUM
2662 && (! reload_completed
|| frame_pointer_needed
))
2663 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
2664 && ! (regno_first
== HARD_FRAME_POINTER_REGNUM
2665 && (! reload_completed
|| frame_pointer_needed
))
2667 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
2668 && ! (regno_first
== ARG_POINTER_REGNUM
&& fixed_regs
[regno_first
])
2672 int some_was_live
= 0, some_was_dead
= 0;
2674 for (i
= regno_first
; i
<= regno_last
; ++i
)
2676 int needed_regno
= REGNO_REG_SET_P (pbi
->reg_live
, i
);
2679 /* Order of the set operation matters here since both
2680 sets may be the same. */
2681 CLEAR_REGNO_REG_SET (pbi
->cond_local_set
, i
);
2682 if (cond
!= NULL_RTX
2683 && ! REGNO_REG_SET_P (pbi
->local_set
, i
))
2684 SET_REGNO_REG_SET (pbi
->cond_local_set
, i
);
2686 SET_REGNO_REG_SET (pbi
->local_set
, i
);
2688 if (code
!= CLOBBER
)
2689 SET_REGNO_REG_SET (pbi
->new_set
, i
);
2691 some_was_live
|= needed_regno
;
2692 some_was_dead
|= ! needed_regno
;
2695 #ifdef HAVE_conditional_execution
2696 /* Consider conditional death in deciding that the register needs
2698 if (some_was_live
&& ! not_dead
2699 /* The stack pointer is never dead. Well, not strictly true,
2700 but it's very difficult to tell from here. Hopefully
2701 combine_stack_adjustments will fix up the most egregious
2703 && regno_first
!= STACK_POINTER_REGNUM
)
2705 for (i
= regno_first
; i
<= regno_last
; ++i
)
2706 if (! mark_regno_cond_dead (pbi
, i
, cond
))
2707 not_dead
|= ((unsigned long) 1) << (i
- regno_first
);
2711 /* Additional data to record if this is the final pass. */
2712 if (flags
& (PROP_LOG_LINKS
| PROP_REG_INFO
2713 | PROP_DEATH_NOTES
| PROP_AUTOINC
))
2716 int blocknum
= pbi
->bb
->index
;
2719 if (flags
& (PROP_LOG_LINKS
| PROP_AUTOINC
))
2721 y
= pbi
->reg_next_use
[regno_first
];
2723 /* The next use is no longer next, since a store intervenes. */
2724 for (i
= regno_first
; i
<= regno_last
; ++i
)
2725 pbi
->reg_next_use
[i
] = 0;
2728 if (flags
& PROP_REG_INFO
)
2730 for (i
= regno_first
; i
<= regno_last
; ++i
)
2732 /* Count (weighted) references, stores, etc. This counts a
2733 register twice if it is modified, but that is correct. */
2734 REG_N_SETS (i
) += 1;
2735 REG_N_REFS (i
) += 1;
2736 REG_FREQ (i
) += REG_FREQ_FROM_BB (pbi
->bb
);
2738 /* The insns where a reg is live are normally counted
2739 elsewhere, but we want the count to include the insn
2740 where the reg is set, and the normal counting mechanism
2741 would not count it. */
2742 REG_LIVE_LENGTH (i
) += 1;
2745 /* If this is a hard reg, record this function uses the reg. */
2746 if (regno_first
< FIRST_PSEUDO_REGISTER
)
2748 for (i
= regno_first
; i
<= regno_last
; i
++)
2749 regs_ever_live
[i
] = 1;
2750 if (flags
& PROP_ASM_SCAN
)
2751 for (i
= regno_first
; i
<= regno_last
; i
++)
2752 regs_asm_clobbered
[i
] = 1;
2756 /* Keep track of which basic blocks each reg appears in. */
2757 if (REG_BASIC_BLOCK (regno_first
) == REG_BLOCK_UNKNOWN
)
2758 REG_BASIC_BLOCK (regno_first
) = blocknum
;
2759 else if (REG_BASIC_BLOCK (regno_first
) != blocknum
)
2760 REG_BASIC_BLOCK (regno_first
) = REG_BLOCK_GLOBAL
;
2764 if (! some_was_dead
)
2766 if (flags
& PROP_LOG_LINKS
)
2768 /* Make a logical link from the next following insn
2769 that uses this register, back to this insn.
2770 The following insns have already been processed.
2772 We don't build a LOG_LINK for hard registers containing
2773 in ASM_OPERANDs. If these registers get replaced,
2774 we might wind up changing the semantics of the insn,
2775 even if reload can make what appear to be valid
2778 We don't build a LOG_LINK for global registers to
2779 or from a function call. We don't want to let
2780 combine think that it knows what is going on with
2781 global registers. */
2782 if (y
&& (BLOCK_NUM (y
) == blocknum
)
2783 && (regno_first
>= FIRST_PSEUDO_REGISTER
2784 || (asm_noperands (PATTERN (y
)) < 0
2785 && ! ((GET_CODE (insn
) == CALL_INSN
2786 || GET_CODE (y
) == CALL_INSN
)
2787 && global_regs
[regno_first
]))))
2788 LOG_LINKS (y
) = alloc_INSN_LIST (insn
, LOG_LINKS (y
));
2793 else if (! some_was_live
)
2795 if (flags
& PROP_REG_INFO
)
2796 REG_N_DEATHS (regno_first
) += 1;
2798 if (flags
& PROP_DEATH_NOTES
)
2800 /* Note that dead stores have already been deleted
2801 when possible. If we get here, we have found a
2802 dead store that cannot be eliminated (because the
2803 same insn does something useful). Indicate this
2804 by marking the reg being set as dying here. */
2806 = alloc_EXPR_LIST (REG_UNUSED
, reg
, REG_NOTES (insn
));
2811 if (flags
& PROP_DEATH_NOTES
)
2813 /* This is a case where we have a multi-word hard register
2814 and some, but not all, of the words of the register are
2815 needed in subsequent insns. Write REG_UNUSED notes
2816 for those parts that were not needed. This case should
2819 for (i
= regno_first
; i
<= regno_last
; ++i
)
2820 if (! REGNO_REG_SET_P (pbi
->reg_live
, i
))
2822 = alloc_EXPR_LIST (REG_UNUSED
,
2829 /* Mark the register as being dead. */
2831 /* The stack pointer is never dead. Well, not strictly true,
2832 but it's very difficult to tell from here. Hopefully
2833 combine_stack_adjustments will fix up the most egregious
2835 && regno_first
!= STACK_POINTER_REGNUM
)
2837 for (i
= regno_first
; i
<= regno_last
; ++i
)
2838 if (!(not_dead
& (((unsigned long) 1) << (i
- regno_first
))))
2839 CLEAR_REGNO_REG_SET (pbi
->reg_live
, i
);
2842 else if (GET_CODE (reg
) == REG
)
2844 if (flags
& (PROP_LOG_LINKS
| PROP_AUTOINC
))
2845 pbi
->reg_next_use
[regno_first
] = 0;
2847 if ((flags
& PROP_REG_INFO
) != 0
2848 && (flags
& PROP_ASM_SCAN
) != 0
2849 && regno_first
< FIRST_PSEUDO_REGISTER
)
2851 for (i
= regno_first
; i
<= regno_last
; i
++)
2852 regs_asm_clobbered
[i
] = 1;
2856 /* If this is the last pass and this is a SCRATCH, show it will be dying
2857 here and count it. */
2858 else if (GET_CODE (reg
) == SCRATCH
)
2860 if (flags
& PROP_DEATH_NOTES
)
2862 = alloc_EXPR_LIST (REG_UNUSED
, reg
, REG_NOTES (insn
));
2866 #ifdef HAVE_conditional_execution
2867 /* Mark REGNO conditionally dead.
2868 Return true if the register is now unconditionally dead. */
2871 mark_regno_cond_dead (struct propagate_block_info
*pbi
, int regno
, rtx cond
)
2873 /* If this is a store to a predicate register, the value of the
2874 predicate is changing, we don't know that the predicate as seen
2875 before is the same as that seen after. Flush all dependent
2876 conditions from reg_cond_dead. This will make all such
2877 conditionally live registers unconditionally live. */
2878 if (REGNO_REG_SET_P (pbi
->reg_cond_reg
, regno
))
2879 flush_reg_cond_reg (pbi
, regno
);
2881 /* If this is an unconditional store, remove any conditional
2882 life that may have existed. */
2883 if (cond
== NULL_RTX
)
2884 splay_tree_remove (pbi
->reg_cond_dead
, regno
);
2887 splay_tree_node node
;
2888 struct reg_cond_life_info
*rcli
;
2891 /* Otherwise this is a conditional set. Record that fact.
2892 It may have been conditionally used, or there may be a
2893 subsequent set with a complimentary condition. */
2895 node
= splay_tree_lookup (pbi
->reg_cond_dead
, regno
);
2898 /* The register was unconditionally live previously.
2899 Record the current condition as the condition under
2900 which it is dead. */
2901 rcli
= xmalloc (sizeof (*rcli
));
2902 rcli
->condition
= cond
;
2903 rcli
->stores
= cond
;
2904 rcli
->orig_condition
= const0_rtx
;
2905 splay_tree_insert (pbi
->reg_cond_dead
, regno
,
2906 (splay_tree_value
) rcli
);
2908 SET_REGNO_REG_SET (pbi
->reg_cond_reg
, REGNO (XEXP (cond
, 0)));
2910 /* Not unconditionally dead. */
2915 /* The register was conditionally live previously.
2916 Add the new condition to the old. */
2917 rcli
= (struct reg_cond_life_info
*) node
->value
;
2918 ncond
= rcli
->condition
;
2919 ncond
= ior_reg_cond (ncond
, cond
, 1);
2920 if (rcli
->stores
== const0_rtx
)
2921 rcli
->stores
= cond
;
2922 else if (rcli
->stores
!= const1_rtx
)
2923 rcli
->stores
= ior_reg_cond (rcli
->stores
, cond
, 1);
2925 /* If the register is now unconditionally dead, remove the entry
2926 in the splay_tree. A register is unconditionally dead if the
2927 dead condition ncond is true. A register is also unconditionally
2928 dead if the sum of all conditional stores is an unconditional
2929 store (stores is true), and the dead condition is identically the
2930 same as the original dead condition initialized at the end of
2931 the block. This is a pointer compare, not an rtx_equal_p
2933 if (ncond
== const1_rtx
2934 || (ncond
== rcli
->orig_condition
&& rcli
->stores
== const1_rtx
))
2935 splay_tree_remove (pbi
->reg_cond_dead
, regno
);
2938 rcli
->condition
= ncond
;
2940 SET_REGNO_REG_SET (pbi
->reg_cond_reg
, REGNO (XEXP (cond
, 0)));
2942 /* Not unconditionally dead. */
2951 /* Called from splay_tree_delete for pbi->reg_cond_life. */
2954 free_reg_cond_life_info (splay_tree_value value
)
2956 struct reg_cond_life_info
*rcli
= (struct reg_cond_life_info
*) value
;
2960 /* Helper function for flush_reg_cond_reg. */
2963 flush_reg_cond_reg_1 (splay_tree_node node
, void *data
)
2965 struct reg_cond_life_info
*rcli
;
2966 int *xdata
= (int *) data
;
2967 unsigned int regno
= xdata
[0];
2969 /* Don't need to search if last flushed value was farther on in
2970 the in-order traversal. */
2971 if (xdata
[1] >= (int) node
->key
)
2974 /* Splice out portions of the expression that refer to regno. */
2975 rcli
= (struct reg_cond_life_info
*) node
->value
;
2976 rcli
->condition
= elim_reg_cond (rcli
->condition
, regno
);
2977 if (rcli
->stores
!= const0_rtx
&& rcli
->stores
!= const1_rtx
)
2978 rcli
->stores
= elim_reg_cond (rcli
->stores
, regno
);
2980 /* If the entire condition is now false, signal the node to be removed. */
2981 if (rcli
->condition
== const0_rtx
)
2983 xdata
[1] = node
->key
;
2986 else if (rcli
->condition
== const1_rtx
)
2992 /* Flush all (sub) expressions referring to REGNO from REG_COND_LIVE. */
2995 flush_reg_cond_reg (struct propagate_block_info
*pbi
, int regno
)
3001 while (splay_tree_foreach (pbi
->reg_cond_dead
,
3002 flush_reg_cond_reg_1
, pair
) == -1)
3003 splay_tree_remove (pbi
->reg_cond_dead
, pair
[1]);
3005 CLEAR_REGNO_REG_SET (pbi
->reg_cond_reg
, regno
);
3008 /* Logical arithmetic on predicate conditions. IOR, NOT and AND.
3009 For ior/and, the ADD flag determines whether we want to add the new
3010 condition X to the old one unconditionally. If it is zero, we will
3011 only return a new expression if X allows us to simplify part of
3012 OLD, otherwise we return NULL to the caller.
3013 If ADD is nonzero, we will return a new condition in all cases. The
3014 toplevel caller of one of these functions should always pass 1 for
3018 ior_reg_cond (rtx old
, rtx x
, int add
)
3022 if (GET_RTX_CLASS (GET_CODE (old
)) == '<')
3024 if (GET_RTX_CLASS (GET_CODE (x
)) == '<'
3025 && REVERSE_CONDEXEC_PREDICATES_P (GET_CODE (x
), GET_CODE (old
))
3026 && REGNO (XEXP (x
, 0)) == REGNO (XEXP (old
, 0)))
3028 if (GET_CODE (x
) == GET_CODE (old
)
3029 && REGNO (XEXP (x
, 0)) == REGNO (XEXP (old
, 0)))
3033 return gen_rtx_IOR (0, old
, x
);
3036 switch (GET_CODE (old
))
3039 op0
= ior_reg_cond (XEXP (old
, 0), x
, 0);
3040 op1
= ior_reg_cond (XEXP (old
, 1), x
, 0);
3041 if (op0
!= NULL
|| op1
!= NULL
)
3043 if (op0
== const0_rtx
)
3044 return op1
? op1
: gen_rtx_IOR (0, XEXP (old
, 1), x
);
3045 if (op1
== const0_rtx
)
3046 return op0
? op0
: gen_rtx_IOR (0, XEXP (old
, 0), x
);
3047 if (op0
== const1_rtx
|| op1
== const1_rtx
)
3050 op0
= gen_rtx_IOR (0, XEXP (old
, 0), x
);
3051 else if (rtx_equal_p (x
, op0
))
3052 /* (x | A) | x ~ (x | A). */
3055 op1
= gen_rtx_IOR (0, XEXP (old
, 1), x
);
3056 else if (rtx_equal_p (x
, op1
))
3057 /* (A | x) | x ~ (A | x). */
3059 return gen_rtx_IOR (0, op0
, op1
);
3063 return gen_rtx_IOR (0, old
, x
);
3066 op0
= ior_reg_cond (XEXP (old
, 0), x
, 0);
3067 op1
= ior_reg_cond (XEXP (old
, 1), x
, 0);
3068 if (op0
!= NULL
|| op1
!= NULL
)
3070 if (op0
== const1_rtx
)
3071 return op1
? op1
: gen_rtx_IOR (0, XEXP (old
, 1), x
);
3072 if (op1
== const1_rtx
)
3073 return op0
? op0
: gen_rtx_IOR (0, XEXP (old
, 0), x
);
3074 if (op0
== const0_rtx
|| op1
== const0_rtx
)
3077 op0
= gen_rtx_IOR (0, XEXP (old
, 0), x
);
3078 else if (rtx_equal_p (x
, op0
))
3079 /* (x & A) | x ~ x. */
3082 op1
= gen_rtx_IOR (0, XEXP (old
, 1), x
);
3083 else if (rtx_equal_p (x
, op1
))
3084 /* (A & x) | x ~ x. */
3086 return gen_rtx_AND (0, op0
, op1
);
3090 return gen_rtx_IOR (0, old
, x
);
3093 op0
= and_reg_cond (XEXP (old
, 0), not_reg_cond (x
), 0);
3095 return not_reg_cond (op0
);
3098 return gen_rtx_IOR (0, old
, x
);
3106 not_reg_cond (rtx x
)
3108 enum rtx_code x_code
;
3110 if (x
== const0_rtx
)
3112 else if (x
== const1_rtx
)
3114 x_code
= GET_CODE (x
);
3117 if (GET_RTX_CLASS (x_code
) == '<'
3118 && GET_CODE (XEXP (x
, 0)) == REG
)
3120 if (XEXP (x
, 1) != const0_rtx
)
3123 return gen_rtx_fmt_ee (reverse_condition (x_code
),
3124 VOIDmode
, XEXP (x
, 0), const0_rtx
);
3126 return gen_rtx_NOT (0, x
);
3130 and_reg_cond (rtx old
, rtx x
, int add
)
3134 if (GET_RTX_CLASS (GET_CODE (old
)) == '<')
3136 if (GET_RTX_CLASS (GET_CODE (x
)) == '<'
3137 && GET_CODE (x
) == reverse_condition (GET_CODE (old
))
3138 && REGNO (XEXP (x
, 0)) == REGNO (XEXP (old
, 0)))
3140 if (GET_CODE (x
) == GET_CODE (old
)
3141 && REGNO (XEXP (x
, 0)) == REGNO (XEXP (old
, 0)))
3145 return gen_rtx_AND (0, old
, x
);
3148 switch (GET_CODE (old
))
3151 op0
= and_reg_cond (XEXP (old
, 0), x
, 0);
3152 op1
= and_reg_cond (XEXP (old
, 1), x
, 0);
3153 if (op0
!= NULL
|| op1
!= NULL
)
3155 if (op0
== const0_rtx
)
3156 return op1
? op1
: gen_rtx_AND (0, XEXP (old
, 1), x
);
3157 if (op1
== const0_rtx
)
3158 return op0
? op0
: gen_rtx_AND (0, XEXP (old
, 0), x
);
3159 if (op0
== const1_rtx
|| op1
== const1_rtx
)
3162 op0
= gen_rtx_AND (0, XEXP (old
, 0), x
);
3163 else if (rtx_equal_p (x
, op0
))
3164 /* (x | A) & x ~ x. */
3167 op1
= gen_rtx_AND (0, XEXP (old
, 1), x
);
3168 else if (rtx_equal_p (x
, op1
))
3169 /* (A | x) & x ~ x. */
3171 return gen_rtx_IOR (0, op0
, op1
);
3175 return gen_rtx_AND (0, old
, x
);
3178 op0
= and_reg_cond (XEXP (old
, 0), x
, 0);
3179 op1
= and_reg_cond (XEXP (old
, 1), x
, 0);
3180 if (op0
!= NULL
|| op1
!= NULL
)
3182 if (op0
== const1_rtx
)
3183 return op1
? op1
: gen_rtx_AND (0, XEXP (old
, 1), x
);
3184 if (op1
== const1_rtx
)
3185 return op0
? op0
: gen_rtx_AND (0, XEXP (old
, 0), x
);
3186 if (op0
== const0_rtx
|| op1
== const0_rtx
)
3189 op0
= gen_rtx_AND (0, XEXP (old
, 0), x
);
3190 else if (rtx_equal_p (x
, op0
))
3191 /* (x & A) & x ~ (x & A). */
3194 op1
= gen_rtx_AND (0, XEXP (old
, 1), x
);
3195 else if (rtx_equal_p (x
, op1
))
3196 /* (A & x) & x ~ (A & x). */
3198 return gen_rtx_AND (0, op0
, op1
);
3202 return gen_rtx_AND (0, old
, x
);
3205 op0
= ior_reg_cond (XEXP (old
, 0), not_reg_cond (x
), 0);
3207 return not_reg_cond (op0
);
3210 return gen_rtx_AND (0, old
, x
);
3217 /* Given a condition X, remove references to reg REGNO and return the
3218 new condition. The removal will be done so that all conditions
3219 involving REGNO are considered to evaluate to false. This function
3220 is used when the value of REGNO changes. */
3223 elim_reg_cond (rtx x
, unsigned int regno
)
3227 if (GET_RTX_CLASS (GET_CODE (x
)) == '<')
3229 if (REGNO (XEXP (x
, 0)) == regno
)
3234 switch (GET_CODE (x
))
3237 op0
= elim_reg_cond (XEXP (x
, 0), regno
);
3238 op1
= elim_reg_cond (XEXP (x
, 1), regno
);
3239 if (op0
== const0_rtx
|| op1
== const0_rtx
)
3241 if (op0
== const1_rtx
)
3243 if (op1
== const1_rtx
)
3245 if (op0
== XEXP (x
, 0) && op1
== XEXP (x
, 1))
3247 return gen_rtx_AND (0, op0
, op1
);
3250 op0
= elim_reg_cond (XEXP (x
, 0), regno
);
3251 op1
= elim_reg_cond (XEXP (x
, 1), regno
);
3252 if (op0
== const1_rtx
|| op1
== const1_rtx
)
3254 if (op0
== const0_rtx
)
3256 if (op1
== const0_rtx
)
3258 if (op0
== XEXP (x
, 0) && op1
== XEXP (x
, 1))
3260 return gen_rtx_IOR (0, op0
, op1
);
3263 op0
= elim_reg_cond (XEXP (x
, 0), regno
);
3264 if (op0
== const0_rtx
)
3266 if (op0
== const1_rtx
)
3268 if (op0
!= XEXP (x
, 0))
3269 return not_reg_cond (op0
);
3276 #endif /* HAVE_conditional_execution */
3280 /* Try to substitute the auto-inc expression INC as the address inside
3281 MEM which occurs in INSN. Currently, the address of MEM is an expression
3282 involving INCR_REG, and INCR is the next use of INCR_REG; it is an insn
3283 that has a single set whose source is a PLUS of INCR_REG and something
3287 attempt_auto_inc (struct propagate_block_info
*pbi
, rtx inc
, rtx insn
,
3288 rtx mem
, rtx incr
, rtx incr_reg
)
3290 int regno
= REGNO (incr_reg
);
3291 rtx set
= single_set (incr
);
3292 rtx q
= SET_DEST (set
);
3293 rtx y
= SET_SRC (set
);
3294 int opnum
= XEXP (y
, 0) == incr_reg
? 0 : 1;
3296 /* Make sure this reg appears only once in this insn. */
3297 if (count_occurrences (PATTERN (insn
), incr_reg
, 1) != 1)
3300 if (dead_or_set_p (incr
, incr_reg
)
3301 /* Mustn't autoinc an eliminable register. */
3302 && (regno
>= FIRST_PSEUDO_REGISTER
3303 || ! TEST_HARD_REG_BIT (elim_reg_set
, regno
)))
3305 /* This is the simple case. Try to make the auto-inc. If
3306 we can't, we are done. Otherwise, we will do any
3307 needed updates below. */
3308 if (! validate_change (insn
, &XEXP (mem
, 0), inc
, 0))
3311 else if (GET_CODE (q
) == REG
3312 /* PREV_INSN used here to check the semi-open interval
3314 && ! reg_used_between_p (q
, PREV_INSN (insn
), incr
)
3315 /* We must also check for sets of q as q may be
3316 a call clobbered hard register and there may
3317 be a call between PREV_INSN (insn) and incr. */
3318 && ! reg_set_between_p (q
, PREV_INSN (insn
), incr
))
3320 /* We have *p followed sometime later by q = p+size.
3321 Both p and q must be live afterward,
3322 and q is not used between INSN and its assignment.
3323 Change it to q = p, ...*q..., q = q+size.
3324 Then fall into the usual case. */
3328 emit_move_insn (q
, incr_reg
);
3329 insns
= get_insns ();
3332 /* If we can't make the auto-inc, or can't make the
3333 replacement into Y, exit. There's no point in making
3334 the change below if we can't do the auto-inc and doing
3335 so is not correct in the pre-inc case. */
3338 validate_change (insn
, &XEXP (mem
, 0), inc
, 1);
3339 validate_change (incr
, &XEXP (y
, opnum
), q
, 1);
3340 if (! apply_change_group ())
3343 /* We now know we'll be doing this change, so emit the
3344 new insn(s) and do the updates. */
3345 emit_insn_before (insns
, insn
);
3347 if (BB_HEAD (pbi
->bb
) == insn
)
3348 BB_HEAD (pbi
->bb
) = insns
;
3350 /* INCR will become a NOTE and INSN won't contain a
3351 use of INCR_REG. If a use of INCR_REG was just placed in
3352 the insn before INSN, make that the next use.
3353 Otherwise, invalidate it. */
3354 if (GET_CODE (PREV_INSN (insn
)) == INSN
3355 && GET_CODE (PATTERN (PREV_INSN (insn
))) == SET
3356 && SET_SRC (PATTERN (PREV_INSN (insn
))) == incr_reg
)
3357 pbi
->reg_next_use
[regno
] = PREV_INSN (insn
);
3359 pbi
->reg_next_use
[regno
] = 0;
3364 /* REGNO is now used in INCR which is below INSN, but
3365 it previously wasn't live here. If we don't mark
3366 it as live, we'll put a REG_DEAD note for it
3367 on this insn, which is incorrect. */
3368 SET_REGNO_REG_SET (pbi
->reg_live
, regno
);
3370 /* If there are any calls between INSN and INCR, show
3371 that REGNO now crosses them. */
3372 for (temp
= insn
; temp
!= incr
; temp
= NEXT_INSN (temp
))
3373 if (GET_CODE (temp
) == CALL_INSN
)
3375 REG_N_CALLS_CROSSED (regno
)++;
3376 if (can_throw_internal (temp
))
3377 REG_N_THROWING_CALLS_CROSSED (regno
)++;
3380 /* Invalidate alias info for Q since we just changed its value. */
3381 clear_reg_alias_info (q
);
3386 /* If we haven't returned, it means we were able to make the
3387 auto-inc, so update the status. First, record that this insn
3388 has an implicit side effect. */
3390 REG_NOTES (insn
) = alloc_EXPR_LIST (REG_INC
, incr_reg
, REG_NOTES (insn
));
3392 /* Modify the old increment-insn to simply copy
3393 the already-incremented value of our register. */
3394 if (! validate_change (incr
, &SET_SRC (set
), incr_reg
, 0))
3397 /* If that makes it a no-op (copying the register into itself) delete
3398 it so it won't appear to be a "use" and a "set" of this
3400 if (REGNO (SET_DEST (set
)) == REGNO (incr_reg
))
3402 /* If the original source was dead, it's dead now. */
3405 while ((note
= find_reg_note (incr
, REG_DEAD
, NULL_RTX
)) != NULL_RTX
)
3407 remove_note (incr
, note
);
3408 if (XEXP (note
, 0) != incr_reg
)
3409 CLEAR_REGNO_REG_SET (pbi
->reg_live
, REGNO (XEXP (note
, 0)));
3412 PUT_CODE (incr
, NOTE
);
3413 NOTE_LINE_NUMBER (incr
) = NOTE_INSN_DELETED
;
3414 NOTE_SOURCE_FILE (incr
) = 0;
3417 if (regno
>= FIRST_PSEUDO_REGISTER
)
3419 /* Count an extra reference to the reg. When a reg is
3420 incremented, spilling it is worse, so we want to make
3421 that less likely. */
3422 REG_FREQ (regno
) += REG_FREQ_FROM_BB (pbi
->bb
);
3424 /* Count the increment as a setting of the register,
3425 even though it isn't a SET in rtl. */
3426 REG_N_SETS (regno
)++;
3430 /* X is a MEM found in INSN. See if we can convert it into an auto-increment
3434 find_auto_inc (struct propagate_block_info
*pbi
, rtx x
, rtx insn
)
3436 rtx addr
= XEXP (x
, 0);
3437 HOST_WIDE_INT offset
= 0;
3438 rtx set
, y
, incr
, inc_val
;
3440 int size
= GET_MODE_SIZE (GET_MODE (x
));
3442 if (GET_CODE (insn
) == JUMP_INSN
)
3445 /* Here we detect use of an index register which might be good for
3446 postincrement, postdecrement, preincrement, or predecrement. */
3448 if (GET_CODE (addr
) == PLUS
&& GET_CODE (XEXP (addr
, 1)) == CONST_INT
)
3449 offset
= INTVAL (XEXP (addr
, 1)), addr
= XEXP (addr
, 0);
3451 if (GET_CODE (addr
) != REG
)
3454 regno
= REGNO (addr
);
3456 /* Is the next use an increment that might make auto-increment? */
3457 incr
= pbi
->reg_next_use
[regno
];
3458 if (incr
== 0 || BLOCK_NUM (incr
) != BLOCK_NUM (insn
))
3460 set
= single_set (incr
);
3461 if (set
== 0 || GET_CODE (set
) != SET
)
3465 if (GET_CODE (y
) != PLUS
)
3468 if (REG_P (XEXP (y
, 0)) && REGNO (XEXP (y
, 0)) == REGNO (addr
))
3469 inc_val
= XEXP (y
, 1);
3470 else if (REG_P (XEXP (y
, 1)) && REGNO (XEXP (y
, 1)) == REGNO (addr
))
3471 inc_val
= XEXP (y
, 0);
3475 if (GET_CODE (inc_val
) == CONST_INT
)
3477 if (HAVE_POST_INCREMENT
3478 && (INTVAL (inc_val
) == size
&& offset
== 0))
3479 attempt_auto_inc (pbi
, gen_rtx_POST_INC (Pmode
, addr
), insn
, x
,
3481 else if (HAVE_POST_DECREMENT
3482 && (INTVAL (inc_val
) == -size
&& offset
== 0))
3483 attempt_auto_inc (pbi
, gen_rtx_POST_DEC (Pmode
, addr
), insn
, x
,
3485 else if (HAVE_PRE_INCREMENT
3486 && (INTVAL (inc_val
) == size
&& offset
== size
))
3487 attempt_auto_inc (pbi
, gen_rtx_PRE_INC (Pmode
, addr
), insn
, x
,
3489 else if (HAVE_PRE_DECREMENT
3490 && (INTVAL (inc_val
) == -size
&& offset
== -size
))
3491 attempt_auto_inc (pbi
, gen_rtx_PRE_DEC (Pmode
, addr
), insn
, x
,
3493 else if (HAVE_POST_MODIFY_DISP
&& offset
== 0)
3494 attempt_auto_inc (pbi
, gen_rtx_POST_MODIFY (Pmode
, addr
,
3495 gen_rtx_PLUS (Pmode
,
3498 insn
, x
, incr
, addr
);
3499 else if (HAVE_PRE_MODIFY_DISP
&& offset
== INTVAL (inc_val
))
3500 attempt_auto_inc (pbi
, gen_rtx_PRE_MODIFY (Pmode
, addr
,
3501 gen_rtx_PLUS (Pmode
,
3504 insn
, x
, incr
, addr
);
3506 else if (GET_CODE (inc_val
) == REG
3507 && ! reg_set_between_p (inc_val
, PREV_INSN (insn
),
3511 if (HAVE_POST_MODIFY_REG
&& offset
== 0)
3512 attempt_auto_inc (pbi
, gen_rtx_POST_MODIFY (Pmode
, addr
,
3513 gen_rtx_PLUS (Pmode
,
3516 insn
, x
, incr
, addr
);
3520 #endif /* AUTO_INC_DEC */
3523 mark_used_reg (struct propagate_block_info
*pbi
, rtx reg
,
3524 rtx cond ATTRIBUTE_UNUSED
, rtx insn
)
3526 unsigned int regno_first
, regno_last
, i
;
3527 int some_was_live
, some_was_dead
, some_not_set
;
3529 regno_last
= regno_first
= REGNO (reg
);
3530 if (regno_first
< FIRST_PSEUDO_REGISTER
)
3531 regno_last
+= HARD_REGNO_NREGS (regno_first
, GET_MODE (reg
)) - 1;
3533 /* Find out if any of this register is live after this instruction. */
3534 some_was_live
= some_was_dead
= 0;
3535 for (i
= regno_first
; i
<= regno_last
; ++i
)
3537 int needed_regno
= REGNO_REG_SET_P (pbi
->reg_live
, i
);
3538 some_was_live
|= needed_regno
;
3539 some_was_dead
|= ! needed_regno
;
3542 /* Find out if any of the register was set this insn. */
3544 for (i
= regno_first
; i
<= regno_last
; ++i
)
3545 some_not_set
|= ! REGNO_REG_SET_P (pbi
->new_set
, i
);
3547 if (pbi
->flags
& (PROP_LOG_LINKS
| PROP_AUTOINC
))
3549 /* Record where each reg is used, so when the reg is set we know
3550 the next insn that uses it. */
3551 pbi
->reg_next_use
[regno_first
] = insn
;
3554 if (pbi
->flags
& PROP_REG_INFO
)
3556 if (regno_first
< FIRST_PSEUDO_REGISTER
)
3558 /* If this is a register we are going to try to eliminate,
3559 don't mark it live here. If we are successful in
3560 eliminating it, it need not be live unless it is used for
3561 pseudos, in which case it will have been set live when it
3562 was allocated to the pseudos. If the register will not
3563 be eliminated, reload will set it live at that point.
3565 Otherwise, record that this function uses this register. */
3566 /* ??? The PPC backend tries to "eliminate" on the pic
3567 register to itself. This should be fixed. In the mean
3568 time, hack around it. */
3570 if (! (TEST_HARD_REG_BIT (elim_reg_set
, regno_first
)
3571 && (regno_first
== FRAME_POINTER_REGNUM
3572 || regno_first
== ARG_POINTER_REGNUM
)))
3573 for (i
= regno_first
; i
<= regno_last
; ++i
)
3574 regs_ever_live
[i
] = 1;
3578 /* Keep track of which basic block each reg appears in. */
3580 int blocknum
= pbi
->bb
->index
;
3581 if (REG_BASIC_BLOCK (regno_first
) == REG_BLOCK_UNKNOWN
)
3582 REG_BASIC_BLOCK (regno_first
) = blocknum
;
3583 else if (REG_BASIC_BLOCK (regno_first
) != blocknum
)
3584 REG_BASIC_BLOCK (regno_first
) = REG_BLOCK_GLOBAL
;
3586 /* Count (weighted) number of uses of each reg. */
3587 REG_FREQ (regno_first
) += REG_FREQ_FROM_BB (pbi
->bb
);
3588 REG_N_REFS (regno_first
)++;
3592 /* Record and count the insns in which a reg dies. If it is used in
3593 this insn and was dead below the insn then it dies in this insn.
3594 If it was set in this insn, we do not make a REG_DEAD note;
3595 likewise if we already made such a note. */
3596 if ((pbi
->flags
& (PROP_DEATH_NOTES
| PROP_REG_INFO
))
3600 /* Check for the case where the register dying partially
3601 overlaps the register set by this insn. */
3602 if (regno_first
!= regno_last
)
3603 for (i
= regno_first
; i
<= regno_last
; ++i
)
3604 some_was_live
|= REGNO_REG_SET_P (pbi
->new_set
, i
);
3606 /* If none of the words in X is needed, make a REG_DEAD note.
3607 Otherwise, we must make partial REG_DEAD notes. */
3608 if (! some_was_live
)
3610 if ((pbi
->flags
& PROP_DEATH_NOTES
)
3611 && ! find_regno_note (insn
, REG_DEAD
, regno_first
))
3613 = alloc_EXPR_LIST (REG_DEAD
, reg
, REG_NOTES (insn
));
3615 if (pbi
->flags
& PROP_REG_INFO
)
3616 REG_N_DEATHS (regno_first
)++;
3620 /* Don't make a REG_DEAD note for a part of a register
3621 that is set in the insn. */
3622 for (i
= regno_first
; i
<= regno_last
; ++i
)
3623 if (! REGNO_REG_SET_P (pbi
->reg_live
, i
)
3624 && ! dead_or_set_regno_p (insn
, i
))
3626 = alloc_EXPR_LIST (REG_DEAD
,
3632 /* Mark the register as being live. */
3633 for (i
= regno_first
; i
<= regno_last
; ++i
)
3635 #ifdef HAVE_conditional_execution
3636 int this_was_live
= REGNO_REG_SET_P (pbi
->reg_live
, i
);
3639 SET_REGNO_REG_SET (pbi
->reg_live
, i
);
3641 #ifdef HAVE_conditional_execution
3642 /* If this is a conditional use, record that fact. If it is later
3643 conditionally set, we'll know to kill the register. */
3644 if (cond
!= NULL_RTX
)
3646 splay_tree_node node
;
3647 struct reg_cond_life_info
*rcli
;
3652 node
= splay_tree_lookup (pbi
->reg_cond_dead
, i
);
3655 /* The register was unconditionally live previously.
3656 No need to do anything. */
3660 /* The register was conditionally live previously.
3661 Subtract the new life cond from the old death cond. */
3662 rcli
= (struct reg_cond_life_info
*) node
->value
;
3663 ncond
= rcli
->condition
;
3664 ncond
= and_reg_cond (ncond
, not_reg_cond (cond
), 1);
3666 /* If the register is now unconditionally live,
3667 remove the entry in the splay_tree. */
3668 if (ncond
== const0_rtx
)
3669 splay_tree_remove (pbi
->reg_cond_dead
, i
);
3672 rcli
->condition
= ncond
;
3673 SET_REGNO_REG_SET (pbi
->reg_cond_reg
,
3674 REGNO (XEXP (cond
, 0)));
3680 /* The register was not previously live at all. Record
3681 the condition under which it is still dead. */
3682 rcli
= xmalloc (sizeof (*rcli
));
3683 rcli
->condition
= not_reg_cond (cond
);
3684 rcli
->stores
= const0_rtx
;
3685 rcli
->orig_condition
= const0_rtx
;
3686 splay_tree_insert (pbi
->reg_cond_dead
, i
,
3687 (splay_tree_value
) rcli
);
3689 SET_REGNO_REG_SET (pbi
->reg_cond_reg
, REGNO (XEXP (cond
, 0)));
3692 else if (this_was_live
)
3694 /* The register may have been conditionally live previously, but
3695 is now unconditionally live. Remove it from the conditionally
3696 dead list, so that a conditional set won't cause us to think
3698 splay_tree_remove (pbi
->reg_cond_dead
, i
);
3704 /* Scan expression X and store a 1-bit in NEW_LIVE for each reg it uses.
3705 This is done assuming the registers needed from X are those that
3706 have 1-bits in PBI->REG_LIVE.
3708 INSN is the containing instruction. If INSN is dead, this function
3712 mark_used_regs (struct propagate_block_info
*pbi
, rtx x
, rtx cond
, rtx insn
)
3716 int flags
= pbi
->flags
;
3721 code
= GET_CODE (x
);
3742 /* If we are clobbering a MEM, mark any registers inside the address
3744 if (GET_CODE (XEXP (x
, 0)) == MEM
)
3745 mark_used_regs (pbi
, XEXP (XEXP (x
, 0), 0), cond
, insn
);
3749 /* Don't bother watching stores to mems if this is not the
3750 final pass. We'll not be deleting dead stores this round. */
3751 if (optimize
&& (flags
& PROP_SCAN_DEAD_STORES
))
3753 /* Invalidate the data for the last MEM stored, but only if MEM is
3754 something that can be stored into. */
3755 if (GET_CODE (XEXP (x
, 0)) == SYMBOL_REF
3756 && CONSTANT_POOL_ADDRESS_P (XEXP (x
, 0)))
3757 /* Needn't clear the memory set list. */
3761 rtx temp
= pbi
->mem_set_list
;
3762 rtx prev
= NULL_RTX
;
3767 next
= XEXP (temp
, 1);
3768 if (unchanging_anti_dependence (XEXP (temp
, 0), x
))
3770 /* Splice temp out of the list. */
3772 XEXP (prev
, 1) = next
;
3774 pbi
->mem_set_list
= next
;
3775 free_EXPR_LIST_node (temp
);
3776 pbi
->mem_set_list_len
--;
3784 /* If the memory reference had embedded side effects (autoincrement
3785 address modes. Then we may need to kill some entries on the
3788 for_each_rtx (&PATTERN (insn
), invalidate_mems_from_autoinc
, pbi
);
3792 if (flags
& PROP_AUTOINC
)
3793 find_auto_inc (pbi
, x
, insn
);
3798 #ifdef CANNOT_CHANGE_MODE_CLASS
3799 if (flags
& PROP_REG_INFO
)
3800 record_subregs_of_mode (x
);
3803 /* While we're here, optimize this case. */
3805 if (GET_CODE (x
) != REG
)
3810 /* See a register other than being set => mark it as needed. */
3811 mark_used_reg (pbi
, x
, cond
, insn
);
3816 rtx testreg
= SET_DEST (x
);
3819 /* If storing into MEM, don't show it as being used. But do
3820 show the address as being used. */
3821 if (GET_CODE (testreg
) == MEM
)
3824 if (flags
& PROP_AUTOINC
)
3825 find_auto_inc (pbi
, testreg
, insn
);
3827 mark_used_regs (pbi
, XEXP (testreg
, 0), cond
, insn
);
3828 mark_used_regs (pbi
, SET_SRC (x
), cond
, insn
);
3832 /* Storing in STRICT_LOW_PART is like storing in a reg
3833 in that this SET might be dead, so ignore it in TESTREG.
3834 but in some other ways it is like using the reg.
3836 Storing in a SUBREG or a bit field is like storing the entire
3837 register in that if the register's value is not used
3838 then this SET is not needed. */
3839 while (GET_CODE (testreg
) == STRICT_LOW_PART
3840 || GET_CODE (testreg
) == ZERO_EXTRACT
3841 || GET_CODE (testreg
) == SIGN_EXTRACT
3842 || GET_CODE (testreg
) == SUBREG
)
3844 #ifdef CANNOT_CHANGE_MODE_CLASS
3845 if ((flags
& PROP_REG_INFO
) && GET_CODE (testreg
) == SUBREG
)
3846 record_subregs_of_mode (testreg
);
3849 /* Modifying a single register in an alternate mode
3850 does not use any of the old value. But these other
3851 ways of storing in a register do use the old value. */
3852 if (GET_CODE (testreg
) == SUBREG
3853 && !((REG_BYTES (SUBREG_REG (testreg
))
3854 + UNITS_PER_WORD
- 1) / UNITS_PER_WORD
3855 > (REG_BYTES (testreg
)
3856 + UNITS_PER_WORD
- 1) / UNITS_PER_WORD
))
3861 testreg
= XEXP (testreg
, 0);
3864 /* If this is a store into a register or group of registers,
3865 recursively scan the value being stored. */
3867 if ((GET_CODE (testreg
) == PARALLEL
3868 && GET_MODE (testreg
) == BLKmode
)
3869 || (GET_CODE (testreg
) == REG
3870 && (regno
= REGNO (testreg
),
3871 ! (regno
== FRAME_POINTER_REGNUM
3872 && (! reload_completed
|| frame_pointer_needed
)))
3873 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
3874 && ! (regno
== HARD_FRAME_POINTER_REGNUM
3875 && (! reload_completed
|| frame_pointer_needed
))
3877 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
3878 && ! (regno
== ARG_POINTER_REGNUM
&& fixed_regs
[regno
])
3883 mark_used_regs (pbi
, SET_DEST (x
), cond
, insn
);
3884 mark_used_regs (pbi
, SET_SRC (x
), cond
, insn
);
3891 case UNSPEC_VOLATILE
:
3895 /* Traditional and volatile asm instructions must be considered to use
3896 and clobber all hard registers, all pseudo-registers and all of
3897 memory. So must TRAP_IF and UNSPEC_VOLATILE operations.
3899 Consider for instance a volatile asm that changes the fpu rounding
3900 mode. An insn should not be moved across this even if it only uses
3901 pseudo-regs because it might give an incorrectly rounded result.
3903 ?!? Unfortunately, marking all hard registers as live causes massive
3904 problems for the register allocator and marking all pseudos as live
3905 creates mountains of uninitialized variable warnings.
3907 So for now, just clear the memory set list and mark any regs
3908 we can find in ASM_OPERANDS as used. */
3909 if (code
!= ASM_OPERANDS
|| MEM_VOLATILE_P (x
))
3911 free_EXPR_LIST_list (&pbi
->mem_set_list
);
3912 pbi
->mem_set_list_len
= 0;
3915 /* For all ASM_OPERANDS, we must traverse the vector of input operands.
3916 We can not just fall through here since then we would be confused
3917 by the ASM_INPUT rtx inside ASM_OPERANDS, which do not indicate
3918 traditional asms unlike their normal usage. */
3919 if (code
== ASM_OPERANDS
)
3923 for (j
= 0; j
< ASM_OPERANDS_INPUT_LENGTH (x
); j
++)
3924 mark_used_regs (pbi
, ASM_OPERANDS_INPUT (x
, j
), cond
, insn
);
3930 if (cond
!= NULL_RTX
)
3933 mark_used_regs (pbi
, COND_EXEC_TEST (x
), NULL_RTX
, insn
);
3935 cond
= COND_EXEC_TEST (x
);
3936 x
= COND_EXEC_CODE (x
);
3943 /* Recursively scan the operands of this expression. */
3946 const char * const fmt
= GET_RTX_FORMAT (code
);
3949 for (i
= GET_RTX_LENGTH (code
) - 1; i
>= 0; i
--)
3953 /* Tail recursive case: save a function call level. */
3959 mark_used_regs (pbi
, XEXP (x
, i
), cond
, insn
);
3961 else if (fmt
[i
] == 'E')
3964 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
3965 mark_used_regs (pbi
, XVECEXP (x
, i
, j
), cond
, insn
);
3974 try_pre_increment_1 (struct propagate_block_info
*pbi
, rtx insn
)
3976 /* Find the next use of this reg. If in same basic block,
3977 make it do pre-increment or pre-decrement if appropriate. */
3978 rtx x
= single_set (insn
);
3979 HOST_WIDE_INT amount
= ((GET_CODE (SET_SRC (x
)) == PLUS
? 1 : -1)
3980 * INTVAL (XEXP (SET_SRC (x
), 1)));
3981 int regno
= REGNO (SET_DEST (x
));
3982 rtx y
= pbi
->reg_next_use
[regno
];
3984 && SET_DEST (x
) != stack_pointer_rtx
3985 && BLOCK_NUM (y
) == BLOCK_NUM (insn
)
3986 /* Don't do this if the reg dies, or gets set in y; a standard addressing
3987 mode would be better. */
3988 && ! dead_or_set_p (y
, SET_DEST (x
))
3989 && try_pre_increment (y
, SET_DEST (x
), amount
))
3991 /* We have found a suitable auto-increment and already changed
3992 insn Y to do it. So flush this increment instruction. */
3993 propagate_block_delete_insn (insn
);
3995 /* Count a reference to this reg for the increment insn we are
3996 deleting. When a reg is incremented, spilling it is worse,
3997 so we want to make that less likely. */
3998 if (regno
>= FIRST_PSEUDO_REGISTER
)
4000 REG_FREQ (regno
) += REG_FREQ_FROM_BB (pbi
->bb
);
4001 REG_N_SETS (regno
)++;
4004 /* Flush any remembered memories depending on the value of
4005 the incremented register. */
4006 invalidate_mems_from_set (pbi
, SET_DEST (x
));
4013 /* Try to change INSN so that it does pre-increment or pre-decrement
4014 addressing on register REG in order to add AMOUNT to REG.
4015 AMOUNT is negative for pre-decrement.
4016 Returns 1 if the change could be made.
4017 This checks all about the validity of the result of modifying INSN. */
4020 try_pre_increment (rtx insn
, rtx reg
, HOST_WIDE_INT amount
)
4024 /* Nonzero if we can try to make a pre-increment or pre-decrement.
4025 For example, addl $4,r1; movl (r1),... can become movl +(r1),... */
4027 /* Nonzero if we can try to make a post-increment or post-decrement.
4028 For example, addl $4,r1; movl -4(r1),... can become movl (r1)+,...
4029 It is possible for both PRE_OK and POST_OK to be nonzero if the machine
4030 supports both pre-inc and post-inc, or both pre-dec and post-dec. */
4033 /* Nonzero if the opportunity actually requires post-inc or post-dec. */
4036 /* From the sign of increment, see which possibilities are conceivable
4037 on this target machine. */
4038 if (HAVE_PRE_INCREMENT
&& amount
> 0)
4040 if (HAVE_POST_INCREMENT
&& amount
> 0)
4043 if (HAVE_PRE_DECREMENT
&& amount
< 0)
4045 if (HAVE_POST_DECREMENT
&& amount
< 0)
4048 if (! (pre_ok
|| post_ok
))
4051 /* It is not safe to add a side effect to a jump insn
4052 because if the incremented register is spilled and must be reloaded
4053 there would be no way to store the incremented value back in memory. */
4055 if (GET_CODE (insn
) == JUMP_INSN
)
4060 use
= find_use_as_address (PATTERN (insn
), reg
, 0);
4061 if (post_ok
&& (use
== 0 || use
== (rtx
) (size_t) 1))
4063 use
= find_use_as_address (PATTERN (insn
), reg
, -amount
);
4067 if (use
== 0 || use
== (rtx
) (size_t) 1)
4070 if (GET_MODE_SIZE (GET_MODE (use
)) != (amount
> 0 ? amount
: - amount
))
4073 /* See if this combination of instruction and addressing mode exists. */
4074 if (! validate_change (insn
, &XEXP (use
, 0),
4075 gen_rtx_fmt_e (amount
> 0
4076 ? (do_post
? POST_INC
: PRE_INC
)
4077 : (do_post
? POST_DEC
: PRE_DEC
),
4081 /* Record that this insn now has an implicit side effect on X. */
4082 REG_NOTES (insn
) = alloc_EXPR_LIST (REG_INC
, reg
, REG_NOTES (insn
));
4086 #endif /* AUTO_INC_DEC */
4088 /* Find the place in the rtx X where REG is used as a memory address.
4089 Return the MEM rtx that so uses it.
4090 If PLUSCONST is nonzero, search instead for a memory address equivalent to
4091 (plus REG (const_int PLUSCONST)).
4093 If such an address does not appear, return 0.
4094 If REG appears more than once, or is used other than in such an address,
4098 find_use_as_address (rtx x
, rtx reg
, HOST_WIDE_INT plusconst
)
4100 enum rtx_code code
= GET_CODE (x
);
4101 const char * const fmt
= GET_RTX_FORMAT (code
);
4106 if (code
== MEM
&& XEXP (x
, 0) == reg
&& plusconst
== 0)
4109 if (code
== MEM
&& GET_CODE (XEXP (x
, 0)) == PLUS
4110 && XEXP (XEXP (x
, 0), 0) == reg
4111 && GET_CODE (XEXP (XEXP (x
, 0), 1)) == CONST_INT
4112 && INTVAL (XEXP (XEXP (x
, 0), 1)) == plusconst
)
4115 if (code
== SIGN_EXTRACT
|| code
== ZERO_EXTRACT
)
4117 /* If REG occurs inside a MEM used in a bit-field reference,
4118 that is unacceptable. */
4119 if (find_use_as_address (XEXP (x
, 0), reg
, 0) != 0)
4120 return (rtx
) (size_t) 1;
4124 return (rtx
) (size_t) 1;
4126 for (i
= GET_RTX_LENGTH (code
) - 1; i
>= 0; i
--)
4130 tem
= find_use_as_address (XEXP (x
, i
), reg
, plusconst
);
4134 return (rtx
) (size_t) 1;
4136 else if (fmt
[i
] == 'E')
4139 for (j
= XVECLEN (x
, i
) - 1; j
>= 0; j
--)
4141 tem
= find_use_as_address (XVECEXP (x
, i
, j
), reg
, plusconst
);
4145 return (rtx
) (size_t) 1;
4153 /* Write information about registers and basic blocks into FILE.
4154 This is part of making a debugging dump. */
4157 dump_regset (regset r
, FILE *outf
)
4162 fputs (" (nil)", outf
);
4166 EXECUTE_IF_SET_IN_REG_SET (r
, 0, i
,
4168 fprintf (outf
, " %d", i
);
4169 if (i
< FIRST_PSEUDO_REGISTER
)
4170 fprintf (outf
, " [%s]",
4175 /* Print a human-readable representation of R on the standard error
4176 stream. This function is designed to be used from within the
4180 debug_regset (regset r
)
4182 dump_regset (r
, stderr
);
4183 putc ('\n', stderr
);
4186 /* Recompute register set/reference counts immediately prior to register
4189 This avoids problems with set/reference counts changing to/from values
4190 which have special meanings to the register allocators.
4192 Additionally, the reference counts are the primary component used by the
4193 register allocators to prioritize pseudos for allocation to hard regs.
4194 More accurate reference counts generally lead to better register allocation.
4196 F is the first insn to be scanned.
4198 LOOP_STEP denotes how much loop_depth should be incremented per
4199 loop nesting level in order to increase the ref count more for
4200 references in a loop.
4202 It might be worthwhile to update REG_LIVE_LENGTH, REG_BASIC_BLOCK and
4203 possibly other information which is used by the register allocators. */
4206 recompute_reg_usage (rtx f ATTRIBUTE_UNUSED
, int loop_step ATTRIBUTE_UNUSED
)
4208 allocate_reg_life_data ();
4209 update_life_info (NULL
, UPDATE_LIFE_LOCAL
, PROP_REG_INFO
);
4212 /* Optionally removes all the REG_DEAD and REG_UNUSED notes from a set of
4213 blocks. If BLOCKS is NULL, assume the universal set. Returns a count
4214 of the number of registers that died. */
4217 count_or_remove_death_notes (sbitmap blocks
, int kill
)
4224 /* This used to be a loop over all the blocks with a membership test
4225 inside the loop. That can be amazingly expensive on a large CFG
4226 when only a small number of bits are set in BLOCKs (for example,
4227 the calls from the scheduler typically have very few bits set).
4229 For extra credit, someone should convert BLOCKS to a bitmap rather
4233 EXECUTE_IF_SET_IN_SBITMAP (blocks
, 0, i
,
4235 count
+= count_or_remove_death_notes_bb (BASIC_BLOCK (i
), kill
);
4242 count
+= count_or_remove_death_notes_bb (bb
, kill
);
4249 /* Optionally removes all the REG_DEAD and REG_UNUSED notes from basic
4250 block BB. Returns a count of the number of registers that died. */
4253 count_or_remove_death_notes_bb (basic_block bb
, int kill
)
4258 for (insn
= BB_HEAD (bb
); ; insn
= NEXT_INSN (insn
))
4262 rtx
*pprev
= ®_NOTES (insn
);
4267 switch (REG_NOTE_KIND (link
))
4270 if (GET_CODE (XEXP (link
, 0)) == REG
)
4272 rtx reg
= XEXP (link
, 0);
4275 if (REGNO (reg
) >= FIRST_PSEUDO_REGISTER
)
4278 n
= HARD_REGNO_NREGS (REGNO (reg
), GET_MODE (reg
));
4287 rtx next
= XEXP (link
, 1);
4288 free_EXPR_LIST_node (link
);
4289 *pprev
= link
= next
;
4295 pprev
= &XEXP (link
, 1);
4302 if (insn
== BB_END (bb
))
4309 /* Clear LOG_LINKS fields of insns in a selected blocks or whole chain
4310 if blocks is NULL. */
4313 clear_log_links (sbitmap blocks
)
4320 for (insn
= get_insns (); insn
; insn
= NEXT_INSN (insn
))
4322 free_INSN_LIST_list (&LOG_LINKS (insn
));
4325 EXECUTE_IF_SET_IN_SBITMAP (blocks
, 0, i
,
4327 basic_block bb
= BASIC_BLOCK (i
);
4329 for (insn
= BB_HEAD (bb
); insn
!= NEXT_INSN (BB_END (bb
));
4330 insn
= NEXT_INSN (insn
))
4332 free_INSN_LIST_list (&LOG_LINKS (insn
));
4336 /* Given a register bitmap, turn on the bits in a HARD_REG_SET that
4337 correspond to the hard registers, if any, set in that map. This
4338 could be done far more efficiently by having all sorts of special-cases
4339 with moving single words, but probably isn't worth the trouble. */
4342 reg_set_to_hard_reg_set (HARD_REG_SET
*to
, bitmap from
)
4346 EXECUTE_IF_SET_IN_BITMAP
4349 if (i
>= FIRST_PSEUDO_REGISTER
)
4351 SET_HARD_REG_BIT (*to
, i
);