1 /* Data flow analysis for GNU compiler.
2 Copyright (C) 1987, 1988, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
3 1999, 2000, 2001, 2002 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 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
126 #include "hard-reg-set.h"
127 #include "basic-block.h"
128 #include "insn-config.h"
132 #include "function.h"
141 #include "splay-tree.h"
143 #define obstack_chunk_alloc xmalloc
144 #define obstack_chunk_free free
146 /* EXIT_IGNORE_STACK should be nonzero if, when returning from a function,
147 the stack pointer does not matter. The value is tested only in
148 functions that have frame pointers.
149 No definition is equivalent to always zero. */
150 #ifndef EXIT_IGNORE_STACK
151 #define EXIT_IGNORE_STACK 0
154 #ifndef HAVE_epilogue
155 #define HAVE_epilogue 0
157 #ifndef HAVE_prologue
158 #define HAVE_prologue 0
160 #ifndef HAVE_sibcall_epilogue
161 #define HAVE_sibcall_epilogue 0
165 #define LOCAL_REGNO(REGNO) 0
167 #ifndef EPILOGUE_USES
168 #define EPILOGUE_USES(REGNO) 0
171 #define EH_USES(REGNO) 0
174 #ifdef HAVE_conditional_execution
175 #ifndef REVERSE_CONDEXEC_PREDICATES_P
176 #define REVERSE_CONDEXEC_PREDICATES_P(x, y) ((x) == reverse_condition (y))
180 /* Nonzero if the second flow pass has completed. */
183 /* Maximum register number used in this function, plus one. */
187 /* Indexed by n, giving various register information */
189 varray_type reg_n_info
;
191 /* Size of a regset for the current function,
192 in (1) bytes and (2) elements. */
197 /* Regset of regs live when calls to `setjmp'-like functions happen. */
198 /* ??? Does this exist only for the setjmp-clobbered warning message? */
200 regset regs_live_at_setjmp
;
202 /* List made of EXPR_LIST rtx's which gives pairs of pseudo registers
203 that have to go in the same hard reg.
204 The first two regs in the list are a pair, and the next two
205 are another pair, etc. */
208 /* Callback that determines if it's ok for a function to have no
209 noreturn attribute. */
210 int (*lang_missing_noreturn_ok_p
) PARAMS ((tree
));
212 /* Set of registers that may be eliminable. These are handled specially
213 in updating regs_ever_live. */
215 static HARD_REG_SET elim_reg_set
;
217 /* Holds information for tracking conditional register life information. */
218 struct reg_cond_life_info
220 /* A boolean expression of conditions under which a register is dead. */
222 /* Conditions under which a register is dead at the basic block end. */
225 /* A boolean expression of conditions under which a register has been
229 /* ??? Could store mask of bytes that are dead, so that we could finally
230 track lifetimes of multi-word registers accessed via subregs. */
233 /* For use in communicating between propagate_block and its subroutines.
234 Holds all information needed to compute life and def-use information. */
236 struct propagate_block_info
238 /* The basic block we're considering. */
241 /* Bit N is set if register N is conditionally or unconditionally live. */
244 /* Bit N is set if register N is set this insn. */
247 /* Element N is the next insn that uses (hard or pseudo) register N
248 within the current basic block; or zero, if there is no such insn. */
251 /* Contains a list of all the MEMs we are tracking for dead store
255 /* If non-null, record the set of registers set unconditionally in the
259 /* If non-null, record the set of registers set conditionally in the
261 regset cond_local_set
;
263 #ifdef HAVE_conditional_execution
264 /* Indexed by register number, holds a reg_cond_life_info for each
265 register that is not unconditionally live or dead. */
266 splay_tree reg_cond_dead
;
268 /* Bit N is set if register N is in an expression in reg_cond_dead. */
272 /* The length of mem_set_list. */
273 int mem_set_list_len
;
275 /* Non-zero if the value of CC0 is live. */
278 /* Flags controling the set of information propagate_block collects. */
282 /* Number of dead insns removed. */
285 /* Maximum length of pbi->mem_set_list before we start dropping
286 new elements on the floor. */
287 #define MAX_MEM_SET_LIST_LEN 100
289 /* Forward declarations */
290 static int verify_wide_reg_1
PARAMS ((rtx
*, void *));
291 static void verify_wide_reg
PARAMS ((int, basic_block
));
292 static void verify_local_live_at_start
PARAMS ((regset
, basic_block
));
293 static void notice_stack_pointer_modification_1
PARAMS ((rtx
, rtx
, void *));
294 static void notice_stack_pointer_modification
PARAMS ((rtx
));
295 static void mark_reg
PARAMS ((rtx
, void *));
296 static void mark_regs_live_at_end
PARAMS ((regset
));
297 static int set_phi_alternative_reg
PARAMS ((rtx
, int, int, void *));
298 static void calculate_global_regs_live
PARAMS ((sbitmap
, sbitmap
, int));
299 static void propagate_block_delete_insn
PARAMS ((rtx
));
300 static rtx propagate_block_delete_libcall
PARAMS ((rtx
, rtx
));
301 static int insn_dead_p
PARAMS ((struct propagate_block_info
*,
303 static int libcall_dead_p
PARAMS ((struct propagate_block_info
*,
305 static void mark_set_regs
PARAMS ((struct propagate_block_info
*,
307 static void mark_set_1
PARAMS ((struct propagate_block_info
*,
308 enum rtx_code
, rtx
, rtx
,
310 static int find_regno_partial
PARAMS ((rtx
*, void *));
312 #ifdef HAVE_conditional_execution
313 static int mark_regno_cond_dead
PARAMS ((struct propagate_block_info
*,
315 static void free_reg_cond_life_info
PARAMS ((splay_tree_value
));
316 static int flush_reg_cond_reg_1
PARAMS ((splay_tree_node
, void *));
317 static void flush_reg_cond_reg
PARAMS ((struct propagate_block_info
*,
319 static rtx elim_reg_cond
PARAMS ((rtx
, unsigned int));
320 static rtx ior_reg_cond
PARAMS ((rtx
, rtx
, int));
321 static rtx not_reg_cond
PARAMS ((rtx
));
322 static rtx and_reg_cond
PARAMS ((rtx
, rtx
, int));
325 static void attempt_auto_inc
PARAMS ((struct propagate_block_info
*,
326 rtx
, rtx
, rtx
, rtx
, rtx
));
327 static void find_auto_inc
PARAMS ((struct propagate_block_info
*,
329 static int try_pre_increment_1
PARAMS ((struct propagate_block_info
*,
331 static int try_pre_increment
PARAMS ((rtx
, rtx
, HOST_WIDE_INT
));
333 static void mark_used_reg
PARAMS ((struct propagate_block_info
*,
335 static void mark_used_regs
PARAMS ((struct propagate_block_info
*,
337 void dump_flow_info
PARAMS ((FILE *));
338 void debug_flow_info
PARAMS ((void));
339 static void add_to_mem_set_list
PARAMS ((struct propagate_block_info
*,
341 static void invalidate_mems_from_autoinc
PARAMS ((struct propagate_block_info
*,
343 static void invalidate_mems_from_set
PARAMS ((struct propagate_block_info
*,
345 static void clear_log_links
PARAMS ((sbitmap
));
349 check_function_return_warnings ()
351 if (warn_missing_noreturn
352 && !TREE_THIS_VOLATILE (cfun
->decl
)
353 && EXIT_BLOCK_PTR
->pred
== NULL
354 && (lang_missing_noreturn_ok_p
355 && !lang_missing_noreturn_ok_p (cfun
->decl
)))
356 warning ("function might be possible candidate for attribute `noreturn'");
358 /* If we have a path to EXIT, then we do return. */
359 if (TREE_THIS_VOLATILE (cfun
->decl
)
360 && EXIT_BLOCK_PTR
->pred
!= NULL
)
361 warning ("`noreturn' function does return");
363 /* If the clobber_return_insn appears in some basic block, then we
364 do reach the end without returning a value. */
365 else if (warn_return_type
366 && cfun
->x_clobber_return_insn
!= NULL
367 && EXIT_BLOCK_PTR
->pred
!= NULL
)
369 int max_uid
= get_max_uid ();
371 /* If clobber_return_insn was excised by jump1, then renumber_insns
372 can make max_uid smaller than the number still recorded in our rtx.
373 That's fine, since this is a quick way of verifying that the insn
374 is no longer in the chain. */
375 if (INSN_UID (cfun
->x_clobber_return_insn
) < max_uid
)
377 /* Recompute insn->block mapping, since the initial mapping is
378 set before we delete unreachable blocks. */
379 if (BLOCK_FOR_INSN (cfun
->x_clobber_return_insn
) != NULL
)
380 warning ("control reaches end of non-void function");
385 /* Return the INSN immediately following the NOTE_INSN_BASIC_BLOCK
386 note associated with the BLOCK. */
389 first_insn_after_basic_block_note (block
)
394 /* Get the first instruction in the block. */
397 if (insn
== NULL_RTX
)
399 if (GET_CODE (insn
) == CODE_LABEL
)
400 insn
= NEXT_INSN (insn
);
401 if (!NOTE_INSN_BASIC_BLOCK_P (insn
))
404 return NEXT_INSN (insn
);
407 /* Perform data flow analysis.
408 F is the first insn of the function; FLAGS is a set of PROP_* flags
409 to be used in accumulating flow info. */
412 life_analysis (f
, file
, flags
)
417 #ifdef ELIMINABLE_REGS
419 static const struct {const int from
, to
; } eliminables
[] = ELIMINABLE_REGS
;
422 /* Record which registers will be eliminated. We use this in
425 CLEAR_HARD_REG_SET (elim_reg_set
);
427 #ifdef ELIMINABLE_REGS
428 for (i
= 0; i
< (int) ARRAY_SIZE (eliminables
); i
++)
429 SET_HARD_REG_BIT (elim_reg_set
, eliminables
[i
].from
);
431 SET_HARD_REG_BIT (elim_reg_set
, FRAME_POINTER_REGNUM
);
435 flags
&= ~(PROP_LOG_LINKS
| PROP_AUTOINC
| PROP_ALLOW_CFG_CHANGES
);
437 /* The post-reload life analysis have (on a global basis) the same
438 registers live as was computed by reload itself. elimination
439 Otherwise offsets and such may be incorrect.
441 Reload will make some registers as live even though they do not
444 We don't want to create new auto-incs after reload, since they
445 are unlikely to be useful and can cause problems with shared
447 if (reload_completed
)
448 flags
&= ~(PROP_REG_INFO
| PROP_AUTOINC
);
450 /* We want alias analysis information for local dead store elimination. */
451 if (optimize
&& (flags
& PROP_SCAN_DEAD_CODE
))
452 init_alias_analysis ();
454 /* Always remove no-op moves. Do this before other processing so
455 that we don't have to keep re-scanning them. */
456 delete_noop_moves (f
);
458 /* Some targets can emit simpler epilogues if they know that sp was
459 not ever modified during the function. After reload, of course,
460 we've already emitted the epilogue so there's no sense searching. */
461 if (! reload_completed
)
462 notice_stack_pointer_modification (f
);
464 /* Allocate and zero out data structures that will record the
465 data from lifetime analysis. */
466 allocate_reg_life_data ();
467 allocate_bb_life_data ();
469 /* Find the set of registers live on function exit. */
470 mark_regs_live_at_end (EXIT_BLOCK_PTR
->global_live_at_start
);
472 /* "Update" life info from zero. It'd be nice to begin the
473 relaxation with just the exit and noreturn blocks, but that set
474 is not immediately handy. */
476 if (flags
& PROP_REG_INFO
)
477 memset (regs_ever_live
, 0, sizeof (regs_ever_live
));
478 update_life_info (NULL
, UPDATE_LIFE_GLOBAL
, flags
);
481 if (optimize
&& (flags
& PROP_SCAN_DEAD_CODE
))
482 end_alias_analysis ();
485 dump_flow_info (file
);
487 free_basic_block_vars (1);
489 #ifdef ENABLE_CHECKING
493 /* Search for any REG_LABEL notes which reference deleted labels. */
494 for (insn
= get_insns (); insn
; insn
= NEXT_INSN (insn
))
496 rtx inote
= find_reg_note (insn
, REG_LABEL
, NULL_RTX
);
498 if (inote
&& GET_CODE (inote
) == NOTE_INSN_DELETED_LABEL
)
503 /* Removing dead insns should've made jumptables really dead. */
504 delete_dead_jumptables ();
507 /* A subroutine of verify_wide_reg, called through for_each_rtx.
508 Search for REGNO. If found, return 2 if it is not wider than
512 verify_wide_reg_1 (px
, pregno
)
517 unsigned int regno
= *(int *) pregno
;
519 if (GET_CODE (x
) == REG
&& REGNO (x
) == regno
)
521 if (GET_MODE_BITSIZE (GET_MODE (x
)) <= BITS_PER_WORD
)
528 /* A subroutine of verify_local_live_at_start. Search through insns
529 of BB looking for register REGNO. */
532 verify_wide_reg (regno
, bb
)
536 rtx head
= bb
->head
, end
= bb
->end
;
542 int r
= for_each_rtx (&PATTERN (head
), verify_wide_reg_1
, ®no
);
550 head
= NEXT_INSN (head
);
555 fprintf (rtl_dump_file
, "Register %d died unexpectedly.\n", regno
);
556 dump_bb (bb
, rtl_dump_file
);
561 /* A subroutine of update_life_info. Verify that there are no untoward
562 changes in live_at_start during a local update. */
565 verify_local_live_at_start (new_live_at_start
, bb
)
566 regset new_live_at_start
;
569 if (reload_completed
)
571 /* After reload, there are no pseudos, nor subregs of multi-word
572 registers. The regsets should exactly match. */
573 if (! REG_SET_EQUAL_P (new_live_at_start
, bb
->global_live_at_start
))
577 fprintf (rtl_dump_file
,
578 "live_at_start mismatch in bb %d, aborting\nNew:\n",
580 debug_bitmap_file (rtl_dump_file
, new_live_at_start
);
581 fputs ("Old:\n", rtl_dump_file
);
582 dump_bb (bb
, rtl_dump_file
);
591 /* Find the set of changed registers. */
592 XOR_REG_SET (new_live_at_start
, bb
->global_live_at_start
);
594 EXECUTE_IF_SET_IN_REG_SET (new_live_at_start
, 0, i
,
596 /* No registers should die. */
597 if (REGNO_REG_SET_P (bb
->global_live_at_start
, i
))
601 fprintf (rtl_dump_file
,
602 "Register %d died unexpectedly.\n", i
);
603 dump_bb (bb
, rtl_dump_file
);
608 /* Verify that the now-live register is wider than word_mode. */
609 verify_wide_reg (i
, bb
);
614 /* Updates life information starting with the basic blocks set in BLOCKS.
615 If BLOCKS is null, consider it to be the universal set.
617 If EXTENT is UPDATE_LIFE_LOCAL, such as after splitting or peepholeing,
618 we are only expecting local modifications to basic blocks. If we find
619 extra registers live at the beginning of a block, then we either killed
620 useful data, or we have a broken split that wants data not provided.
621 If we find registers removed from live_at_start, that means we have
622 a broken peephole that is killing a register it shouldn't.
624 ??? This is not true in one situation -- when a pre-reload splitter
625 generates subregs of a multi-word pseudo, current life analysis will
626 lose the kill. So we _can_ have a pseudo go live. How irritating.
628 Including PROP_REG_INFO does not properly refresh regs_ever_live
629 unless the caller resets it to zero. */
632 update_life_info (blocks
, extent
, prop_flags
)
634 enum update_life_extent extent
;
638 regset_head tmp_head
;
641 tmp
= INITIALIZE_REG_SET (tmp_head
);
644 timevar_push ((extent
== UPDATE_LIFE_LOCAL
|| blocks
)
645 ? TV_LIFE_UPDATE
: TV_LIFE
);
647 /* Changes to the CFG are only allowed when
648 doing a global update for the entire CFG. */
649 if ((prop_flags
& PROP_ALLOW_CFG_CHANGES
)
650 && (extent
== UPDATE_LIFE_LOCAL
|| blocks
))
653 /* For a global update, we go through the relaxation process again. */
654 if (extent
!= UPDATE_LIFE_LOCAL
)
660 calculate_global_regs_live (blocks
, blocks
,
661 prop_flags
& (PROP_SCAN_DEAD_CODE
662 | PROP_ALLOW_CFG_CHANGES
));
664 if ((prop_flags
& (PROP_KILL_DEAD_CODE
| PROP_ALLOW_CFG_CHANGES
))
665 != (PROP_KILL_DEAD_CODE
| PROP_ALLOW_CFG_CHANGES
))
668 /* Removing dead code may allow the CFG to be simplified which
669 in turn may allow for further dead code detection / removal. */
670 for (i
= n_basic_blocks
- 1; i
>= 0; --i
)
672 basic_block bb
= BASIC_BLOCK (i
);
674 COPY_REG_SET (tmp
, bb
->global_live_at_end
);
675 changed
|= propagate_block (bb
, tmp
, NULL
, NULL
,
676 prop_flags
& (PROP_SCAN_DEAD_CODE
677 | PROP_KILL_DEAD_CODE
));
680 if (! changed
|| ! cleanup_cfg (CLEANUP_EXPENSIVE
))
684 /* If asked, remove notes from the blocks we'll update. */
685 if (extent
== UPDATE_LIFE_GLOBAL_RM_NOTES
)
686 count_or_remove_death_notes (blocks
, 1);
689 /* Clear log links in case we are asked to (re)compute them. */
690 if (prop_flags
& PROP_LOG_LINKS
)
691 clear_log_links (blocks
);
695 EXECUTE_IF_SET_IN_SBITMAP (blocks
, 0, i
,
697 basic_block bb
= BASIC_BLOCK (i
);
699 COPY_REG_SET (tmp
, bb
->global_live_at_end
);
700 propagate_block (bb
, tmp
, NULL
, NULL
, prop_flags
);
702 if (extent
== UPDATE_LIFE_LOCAL
)
703 verify_local_live_at_start (tmp
, bb
);
708 for (i
= n_basic_blocks
- 1; i
>= 0; --i
)
710 basic_block bb
= BASIC_BLOCK (i
);
712 COPY_REG_SET (tmp
, bb
->global_live_at_end
);
713 propagate_block (bb
, tmp
, NULL
, NULL
, prop_flags
);
715 if (extent
== UPDATE_LIFE_LOCAL
)
716 verify_local_live_at_start (tmp
, bb
);
722 if (prop_flags
& PROP_REG_INFO
)
724 /* The only pseudos that are live at the beginning of the function
725 are those that were not set anywhere in the function. local-alloc
726 doesn't know how to handle these correctly, so mark them as not
727 local to any one basic block. */
728 EXECUTE_IF_SET_IN_REG_SET (ENTRY_BLOCK_PTR
->global_live_at_end
,
729 FIRST_PSEUDO_REGISTER
, i
,
730 { REG_BASIC_BLOCK (i
) = REG_BLOCK_GLOBAL
; });
732 /* We have a problem with any pseudoreg that lives across the setjmp.
733 ANSI says that if a user variable does not change in value between
734 the setjmp and the longjmp, then the longjmp preserves it. This
735 includes longjmp from a place where the pseudo appears dead.
736 (In principle, the value still exists if it is in scope.)
737 If the pseudo goes in a hard reg, some other value may occupy
738 that hard reg where this pseudo is dead, thus clobbering the pseudo.
739 Conclusion: such a pseudo must not go in a hard reg. */
740 EXECUTE_IF_SET_IN_REG_SET (regs_live_at_setjmp
,
741 FIRST_PSEUDO_REGISTER
, i
,
743 if (regno_reg_rtx
[i
] != 0)
745 REG_LIVE_LENGTH (i
) = -1;
746 REG_BASIC_BLOCK (i
) = REG_BLOCK_UNKNOWN
;
750 timevar_pop ((extent
== UPDATE_LIFE_LOCAL
|| blocks
)
751 ? TV_LIFE_UPDATE
: TV_LIFE
);
752 if (ndead
&& rtl_dump_file
)
753 fprintf (rtl_dump_file
, "deleted %i dead insns\n", ndead
);
757 /* Update life information in all blocks where BB_DIRTY is set. */
760 update_life_info_in_dirty_blocks (extent
, prop_flags
)
761 enum update_life_extent extent
;
764 sbitmap update_life_blocks
= sbitmap_alloc (n_basic_blocks
);
769 sbitmap_zero (update_life_blocks
);
770 for (block_num
= 0; block_num
< n_basic_blocks
; block_num
++)
771 if (BASIC_BLOCK (block_num
)->flags
& BB_DIRTY
)
773 SET_BIT (update_life_blocks
, block_num
);
778 retval
= update_life_info (update_life_blocks
, extent
, prop_flags
);
780 sbitmap_free (update_life_blocks
);
784 /* Free the variables allocated by find_basic_blocks.
786 KEEP_HEAD_END_P is non-zero if basic_block_info is not to be freed. */
789 free_basic_block_vars (keep_head_end_p
)
792 if (! keep_head_end_p
)
794 if (basic_block_info
)
797 VARRAY_FREE (basic_block_info
);
801 ENTRY_BLOCK_PTR
->aux
= NULL
;
802 ENTRY_BLOCK_PTR
->global_live_at_end
= NULL
;
803 EXIT_BLOCK_PTR
->aux
= NULL
;
804 EXIT_BLOCK_PTR
->global_live_at_start
= NULL
;
808 /* Delete any insns that copy a register to itself. */
811 delete_noop_moves (f
)
812 rtx f ATTRIBUTE_UNUSED
;
819 for (i
= 0; i
< n_basic_blocks
; i
++)
821 bb
= BASIC_BLOCK (i
);
822 for (insn
= bb
->head
; insn
!= NEXT_INSN (bb
->end
); insn
= next
)
824 next
= NEXT_INSN (insn
);
825 if (INSN_P (insn
) && noop_move_p (insn
))
829 /* If we're about to remove the first insn of a libcall
830 then move the libcall note to the next real insn and
831 update the retval note. */
832 if ((note
= find_reg_note (insn
, REG_LIBCALL
, NULL_RTX
))
833 && XEXP (note
, 0) != insn
)
835 rtx new_libcall_insn
= next_real_insn (insn
);
836 rtx retval_note
= find_reg_note (XEXP (note
, 0),
837 REG_RETVAL
, NULL_RTX
);
838 REG_NOTES (new_libcall_insn
)
839 = gen_rtx_INSN_LIST (REG_LIBCALL
, XEXP (note
, 0),
840 REG_NOTES (new_libcall_insn
));
841 XEXP (retval_note
, 0) = new_libcall_insn
;
844 delete_insn_and_edges (insn
);
849 if (nnoops
&& rtl_dump_file
)
850 fprintf (rtl_dump_file
, "deleted %i noop moves", nnoops
);
854 /* Delete any jump tables never referenced. We can't delete them at the
855 time of removing tablejump insn as they are referenced by the preceding
856 insns computing the destination, so we delay deleting and garbagecollect
857 them once life information is computed. */
859 delete_dead_jumptables ()
862 for (insn
= get_insns (); insn
; insn
= next
)
864 next
= NEXT_INSN (insn
);
865 if (GET_CODE (insn
) == CODE_LABEL
866 && LABEL_NUSES (insn
) == LABEL_PRESERVE_P (insn
)
867 && GET_CODE (next
) == JUMP_INSN
868 && (GET_CODE (PATTERN (next
)) == ADDR_VEC
869 || GET_CODE (PATTERN (next
)) == ADDR_DIFF_VEC
))
872 fprintf (rtl_dump_file
, "Dead jumptable %i removed\n", INSN_UID (insn
));
873 delete_insn (NEXT_INSN (insn
));
875 next
= NEXT_INSN (next
);
880 /* Determine if the stack pointer is constant over the life of the function.
881 Only useful before prologues have been emitted. */
884 notice_stack_pointer_modification_1 (x
, pat
, data
)
886 rtx pat ATTRIBUTE_UNUSED
;
887 void *data ATTRIBUTE_UNUSED
;
889 if (x
== stack_pointer_rtx
890 /* The stack pointer is only modified indirectly as the result
891 of a push until later in flow. See the comments in rtl.texi
892 regarding Embedded Side-Effects on Addresses. */
893 || (GET_CODE (x
) == MEM
894 && GET_RTX_CLASS (GET_CODE (XEXP (x
, 0))) == 'a'
895 && XEXP (XEXP (x
, 0), 0) == stack_pointer_rtx
))
896 current_function_sp_is_unchanging
= 0;
900 notice_stack_pointer_modification (f
)
905 /* Assume that the stack pointer is unchanging if alloca hasn't
907 current_function_sp_is_unchanging
= !current_function_calls_alloca
;
908 if (! current_function_sp_is_unchanging
)
911 for (insn
= f
; insn
; insn
= NEXT_INSN (insn
))
915 /* Check if insn modifies the stack pointer. */
916 note_stores (PATTERN (insn
), notice_stack_pointer_modification_1
,
918 if (! current_function_sp_is_unchanging
)
924 /* Mark a register in SET. Hard registers in large modes get all
925 of their component registers set as well. */
932 regset set
= (regset
) xset
;
933 int regno
= REGNO (reg
);
935 if (GET_MODE (reg
) == BLKmode
)
938 SET_REGNO_REG_SET (set
, regno
);
939 if (regno
< FIRST_PSEUDO_REGISTER
)
941 int n
= HARD_REGNO_NREGS (regno
, GET_MODE (reg
));
943 SET_REGNO_REG_SET (set
, regno
+ n
);
947 /* Mark those regs which are needed at the end of the function as live
948 at the end of the last basic block. */
951 mark_regs_live_at_end (set
)
956 /* If exiting needs the right stack value, consider the stack pointer
957 live at the end of the function. */
958 if ((HAVE_epilogue
&& reload_completed
)
959 || ! EXIT_IGNORE_STACK
960 || (! FRAME_POINTER_REQUIRED
961 && ! current_function_calls_alloca
962 && flag_omit_frame_pointer
)
963 || current_function_sp_is_unchanging
)
965 SET_REGNO_REG_SET (set
, STACK_POINTER_REGNUM
);
968 /* Mark the frame pointer if needed at the end of the function. If
969 we end up eliminating it, it will be removed from the live list
970 of each basic block by reload. */
972 if (! reload_completed
|| frame_pointer_needed
)
974 SET_REGNO_REG_SET (set
, FRAME_POINTER_REGNUM
);
975 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
976 /* If they are different, also mark the hard frame pointer as live. */
977 if (! LOCAL_REGNO (HARD_FRAME_POINTER_REGNUM
))
978 SET_REGNO_REG_SET (set
, HARD_FRAME_POINTER_REGNUM
);
982 #ifndef PIC_OFFSET_TABLE_REG_CALL_CLOBBERED
983 /* Many architectures have a GP register even without flag_pic.
984 Assume the pic register is not in use, or will be handled by
985 other means, if it is not fixed. */
986 if (PIC_OFFSET_TABLE_REGNUM
!= INVALID_REGNUM
987 && fixed_regs
[PIC_OFFSET_TABLE_REGNUM
])
988 SET_REGNO_REG_SET (set
, PIC_OFFSET_TABLE_REGNUM
);
991 /* Mark all global registers, and all registers used by the epilogue
992 as being live at the end of the function since they may be
993 referenced by our caller. */
994 for (i
= 0; i
< FIRST_PSEUDO_REGISTER
; i
++)
995 if (global_regs
[i
] || EPILOGUE_USES (i
))
996 SET_REGNO_REG_SET (set
, i
);
998 if (HAVE_epilogue
&& reload_completed
)
1000 /* Mark all call-saved registers that we actually used. */
1001 for (i
= 0; i
< FIRST_PSEUDO_REGISTER
; i
++)
1002 if (regs_ever_live
[i
] && ! LOCAL_REGNO (i
)
1003 && ! TEST_HARD_REG_BIT (regs_invalidated_by_call
, i
))
1004 SET_REGNO_REG_SET (set
, i
);
1007 #ifdef EH_RETURN_DATA_REGNO
1008 /* Mark the registers that will contain data for the handler. */
1009 if (reload_completed
&& current_function_calls_eh_return
)
1012 unsigned regno
= EH_RETURN_DATA_REGNO(i
);
1013 if (regno
== INVALID_REGNUM
)
1015 SET_REGNO_REG_SET (set
, regno
);
1018 #ifdef EH_RETURN_STACKADJ_RTX
1019 if ((! HAVE_epilogue
|| ! reload_completed
)
1020 && current_function_calls_eh_return
)
1022 rtx tmp
= EH_RETURN_STACKADJ_RTX
;
1023 if (tmp
&& REG_P (tmp
))
1024 mark_reg (tmp
, set
);
1027 #ifdef EH_RETURN_HANDLER_RTX
1028 if ((! HAVE_epilogue
|| ! reload_completed
)
1029 && current_function_calls_eh_return
)
1031 rtx tmp
= EH_RETURN_HANDLER_RTX
;
1032 if (tmp
&& REG_P (tmp
))
1033 mark_reg (tmp
, set
);
1037 /* Mark function return value. */
1038 diddle_return_value (mark_reg
, set
);
1041 /* Callback function for for_each_successor_phi. DATA is a regset.
1042 Sets the SRC_REGNO, the regno of the phi alternative for phi node
1043 INSN, in the regset. */
1046 set_phi_alternative_reg (insn
, dest_regno
, src_regno
, data
)
1047 rtx insn ATTRIBUTE_UNUSED
;
1048 int dest_regno ATTRIBUTE_UNUSED
;
1052 regset live
= (regset
) data
;
1053 SET_REGNO_REG_SET (live
, src_regno
);
1057 /* Propagate global life info around the graph of basic blocks. Begin
1058 considering blocks with their corresponding bit set in BLOCKS_IN.
1059 If BLOCKS_IN is null, consider it the universal set.
1061 BLOCKS_OUT is set for every block that was changed. */
1064 calculate_global_regs_live (blocks_in
, blocks_out
, flags
)
1065 sbitmap blocks_in
, blocks_out
;
1068 basic_block
*queue
, *qhead
, *qtail
, *qend
;
1069 regset tmp
, new_live_at_end
, call_used
;
1070 regset_head tmp_head
, call_used_head
;
1071 regset_head new_live_at_end_head
;
1074 tmp
= INITIALIZE_REG_SET (tmp_head
);
1075 new_live_at_end
= INITIALIZE_REG_SET (new_live_at_end_head
);
1076 call_used
= INITIALIZE_REG_SET (call_used_head
);
1078 /* Inconveniently, this is only readily available in hard reg set form. */
1079 for (i
= 0; i
< FIRST_PSEUDO_REGISTER
; ++i
)
1080 if (call_used_regs
[i
])
1081 SET_REGNO_REG_SET (call_used
, i
);
1083 /* Create a worklist. Allocate an extra slot for ENTRY_BLOCK, and one
1084 because the `head == tail' style test for an empty queue doesn't
1085 work with a full queue. */
1086 queue
= (basic_block
*) xmalloc ((n_basic_blocks
+ 2) * sizeof (*queue
));
1088 qhead
= qend
= queue
+ n_basic_blocks
+ 2;
1090 /* Queue the blocks set in the initial mask. Do this in reverse block
1091 number order so that we are more likely for the first round to do
1092 useful work. We use AUX non-null to flag that the block is queued. */
1095 /* Clear out the garbage that might be hanging out in bb->aux. */
1096 for (i
= n_basic_blocks
- 1; i
>= 0; --i
)
1097 BASIC_BLOCK (i
)->aux
= NULL
;
1099 EXECUTE_IF_SET_IN_SBITMAP (blocks_in
, 0, i
,
1101 basic_block bb
= BASIC_BLOCK (i
);
1108 for (i
= 0; i
< n_basic_blocks
; ++i
)
1110 basic_block bb
= BASIC_BLOCK (i
);
1116 /* We clean aux when we remove the initially-enqueued bbs, but we
1117 don't enqueue ENTRY and EXIT initially, so clean them upfront and
1119 ENTRY_BLOCK_PTR
->aux
= EXIT_BLOCK_PTR
->aux
= NULL
;
1122 sbitmap_zero (blocks_out
);
1124 /* We work through the queue until there are no more blocks. What
1125 is live at the end of this block is precisely the union of what
1126 is live at the beginning of all its successors. So, we set its
1127 GLOBAL_LIVE_AT_END field based on the GLOBAL_LIVE_AT_START field
1128 for its successors. Then, we compute GLOBAL_LIVE_AT_START for
1129 this block by walking through the instructions in this block in
1130 reverse order and updating as we go. If that changed
1131 GLOBAL_LIVE_AT_START, we add the predecessors of the block to the
1132 queue; they will now need to recalculate GLOBAL_LIVE_AT_END.
1134 We are guaranteed to terminate, because GLOBAL_LIVE_AT_START
1135 never shrinks. If a register appears in GLOBAL_LIVE_AT_START, it
1136 must either be live at the end of the block, or used within the
1137 block. In the latter case, it will certainly never disappear
1138 from GLOBAL_LIVE_AT_START. In the former case, the register
1139 could go away only if it disappeared from GLOBAL_LIVE_AT_START
1140 for one of the successor blocks. By induction, that cannot
1142 while (qhead
!= qtail
)
1144 int rescan
, changed
;
1153 /* Begin by propagating live_at_start from the successor blocks. */
1154 CLEAR_REG_SET (new_live_at_end
);
1157 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
1159 basic_block sb
= e
->dest
;
1161 /* Call-clobbered registers die across exception and
1163 /* ??? Abnormal call edges ignored for the moment, as this gets
1164 confused by sibling call edges, which crashes reg-stack. */
1165 if (e
->flags
& EDGE_EH
)
1167 bitmap_operation (tmp
, sb
->global_live_at_start
,
1168 call_used
, BITMAP_AND_COMPL
);
1169 IOR_REG_SET (new_live_at_end
, tmp
);
1172 IOR_REG_SET (new_live_at_end
, sb
->global_live_at_start
);
1174 /* If a target saves one register in another (instead of on
1175 the stack) the save register will need to be live for EH. */
1176 if (e
->flags
& EDGE_EH
)
1177 for (i
= 0; i
< FIRST_PSEUDO_REGISTER
; i
++)
1179 SET_REGNO_REG_SET (new_live_at_end
, i
);
1183 /* This might be a noreturn function that throws. And
1184 even if it isn't, getting the unwind info right helps
1186 for (i
= 0; i
< FIRST_PSEUDO_REGISTER
; i
++)
1188 SET_REGNO_REG_SET (new_live_at_end
, i
);
1191 /* The all-important stack pointer must always be live. */
1192 SET_REGNO_REG_SET (new_live_at_end
, STACK_POINTER_REGNUM
);
1194 /* Before reload, there are a few registers that must be forced
1195 live everywhere -- which might not already be the case for
1196 blocks within infinite loops. */
1197 if (! reload_completed
)
1199 /* Any reference to any pseudo before reload is a potential
1200 reference of the frame pointer. */
1201 SET_REGNO_REG_SET (new_live_at_end
, FRAME_POINTER_REGNUM
);
1203 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
1204 /* Pseudos with argument area equivalences may require
1205 reloading via the argument pointer. */
1206 if (fixed_regs
[ARG_POINTER_REGNUM
])
1207 SET_REGNO_REG_SET (new_live_at_end
, ARG_POINTER_REGNUM
);
1210 /* Any constant, or pseudo with constant equivalences, may
1211 require reloading from memory using the pic register. */
1212 if (PIC_OFFSET_TABLE_REGNUM
!= INVALID_REGNUM
1213 && fixed_regs
[PIC_OFFSET_TABLE_REGNUM
])
1214 SET_REGNO_REG_SET (new_live_at_end
, PIC_OFFSET_TABLE_REGNUM
);
1217 /* Regs used in phi nodes are not included in
1218 global_live_at_start, since they are live only along a
1219 particular edge. Set those regs that are live because of a
1220 phi node alternative corresponding to this particular block. */
1222 for_each_successor_phi (bb
, &set_phi_alternative_reg
,
1225 if (bb
== ENTRY_BLOCK_PTR
)
1227 COPY_REG_SET (bb
->global_live_at_end
, new_live_at_end
);
1231 /* On our first pass through this block, we'll go ahead and continue.
1232 Recognize first pass by local_set NULL. On subsequent passes, we
1233 get to skip out early if live_at_end wouldn't have changed. */
1235 if (bb
->local_set
== NULL
)
1237 bb
->local_set
= OBSTACK_ALLOC_REG_SET (&flow_obstack
);
1238 bb
->cond_local_set
= OBSTACK_ALLOC_REG_SET (&flow_obstack
);
1243 /* If any bits were removed from live_at_end, we'll have to
1244 rescan the block. This wouldn't be necessary if we had
1245 precalculated local_live, however with PROP_SCAN_DEAD_CODE
1246 local_live is really dependent on live_at_end. */
1247 CLEAR_REG_SET (tmp
);
1248 rescan
= bitmap_operation (tmp
, bb
->global_live_at_end
,
1249 new_live_at_end
, BITMAP_AND_COMPL
);
1253 /* If any of the registers in the new live_at_end set are
1254 conditionally set in this basic block, we must rescan.
1255 This is because conditional lifetimes at the end of the
1256 block do not just take the live_at_end set into account,
1257 but also the liveness at the start of each successor
1258 block. We can miss changes in those sets if we only
1259 compare the new live_at_end against the previous one. */
1260 CLEAR_REG_SET (tmp
);
1261 rescan
= bitmap_operation (tmp
, new_live_at_end
,
1262 bb
->cond_local_set
, BITMAP_AND
);
1267 /* Find the set of changed bits. Take this opportunity
1268 to notice that this set is empty and early out. */
1269 CLEAR_REG_SET (tmp
);
1270 changed
= bitmap_operation (tmp
, bb
->global_live_at_end
,
1271 new_live_at_end
, BITMAP_XOR
);
1275 /* If any of the changed bits overlap with local_set,
1276 we'll have to rescan the block. Detect overlap by
1277 the AND with ~local_set turning off bits. */
1278 rescan
= bitmap_operation (tmp
, tmp
, bb
->local_set
,
1283 /* Let our caller know that BB changed enough to require its
1284 death notes updated. */
1286 SET_BIT (blocks_out
, bb
->index
);
1290 /* Add to live_at_start the set of all registers in
1291 new_live_at_end that aren't in the old live_at_end. */
1293 bitmap_operation (tmp
, new_live_at_end
, bb
->global_live_at_end
,
1295 COPY_REG_SET (bb
->global_live_at_end
, new_live_at_end
);
1297 changed
= bitmap_operation (bb
->global_live_at_start
,
1298 bb
->global_live_at_start
,
1305 COPY_REG_SET (bb
->global_live_at_end
, new_live_at_end
);
1307 /* Rescan the block insn by insn to turn (a copy of) live_at_end
1308 into live_at_start. */
1309 propagate_block (bb
, new_live_at_end
, bb
->local_set
,
1310 bb
->cond_local_set
, flags
);
1312 /* If live_at start didn't change, no need to go farther. */
1313 if (REG_SET_EQUAL_P (bb
->global_live_at_start
, new_live_at_end
))
1316 COPY_REG_SET (bb
->global_live_at_start
, new_live_at_end
);
1319 /* Queue all predecessors of BB so that we may re-examine
1320 their live_at_end. */
1321 for (e
= bb
->pred
; e
; e
= e
->pred_next
)
1323 basic_block pb
= e
->src
;
1324 if (pb
->aux
== NULL
)
1335 FREE_REG_SET (new_live_at_end
);
1336 FREE_REG_SET (call_used
);
1340 EXECUTE_IF_SET_IN_SBITMAP (blocks_out
, 0, i
,
1342 basic_block bb
= BASIC_BLOCK (i
);
1343 FREE_REG_SET (bb
->local_set
);
1344 FREE_REG_SET (bb
->cond_local_set
);
1349 for (i
= n_basic_blocks
- 1; i
>= 0; --i
)
1351 basic_block bb
= BASIC_BLOCK (i
);
1352 FREE_REG_SET (bb
->local_set
);
1353 FREE_REG_SET (bb
->cond_local_set
);
1361 /* This structure is used to pass parameters to an from the
1362 the function find_regno_partial(). It is used to pass in the
1363 register number we are looking, as well as to return any rtx
1367 unsigned regno_to_find
;
1369 } find_regno_partial_param
;
1372 /* Find the rtx for the reg numbers specified in 'data' if it is
1373 part of an expression which only uses part of the register. Return
1374 it in the structure passed in. */
1376 find_regno_partial (ptr
, data
)
1380 find_regno_partial_param
*param
= (find_regno_partial_param
*)data
;
1381 unsigned reg
= param
->regno_to_find
;
1382 param
->retval
= NULL_RTX
;
1384 if (*ptr
== NULL_RTX
)
1387 switch (GET_CODE (*ptr
))
1391 case STRICT_LOW_PART
:
1392 if (GET_CODE (XEXP (*ptr
, 0)) == REG
&& REGNO (XEXP (*ptr
, 0)) == reg
)
1394 param
->retval
= XEXP (*ptr
, 0);
1400 if (GET_CODE (SUBREG_REG (*ptr
)) == REG
1401 && REGNO (SUBREG_REG (*ptr
)) == reg
)
1403 param
->retval
= SUBREG_REG (*ptr
);
1415 /* Process all immediate successors of the entry block looking for pseudo
1416 registers which are live on entry. Find all of those whose first
1417 instance is a partial register reference of some kind, and initialize
1418 them to 0 after the entry block. This will prevent bit sets within
1419 registers whose value is unknown, and may contain some kind of sticky
1420 bits we don't want. */
1423 initialize_uninitialized_subregs ()
1427 int reg
, did_something
= 0;
1428 find_regno_partial_param param
;
1430 for (e
= ENTRY_BLOCK_PTR
->succ
; e
; e
= e
->succ_next
)
1432 basic_block bb
= e
->dest
;
1433 regset map
= bb
->global_live_at_start
;
1434 EXECUTE_IF_SET_IN_REG_SET (map
,
1435 FIRST_PSEUDO_REGISTER
, reg
,
1437 int uid
= REGNO_FIRST_UID (reg
);
1440 /* Find an insn which mentions the register we are looking for.
1441 Its preferable to have an instance of the register's rtl since
1442 there may be various flags set which we need to duplicate.
1443 If we can't find it, its probably an automatic whose initial
1444 value doesn't matter, or hopefully something we don't care about. */
1445 for (i
= get_insns (); i
&& INSN_UID (i
) != uid
; i
= NEXT_INSN (i
))
1449 /* Found the insn, now get the REG rtx, if we can. */
1450 param
.regno_to_find
= reg
;
1451 for_each_rtx (&i
, find_regno_partial
, ¶m
);
1452 if (param
.retval
!= NULL_RTX
)
1454 insn
= gen_move_insn (param
.retval
,
1455 CONST0_RTX (GET_MODE (param
.retval
)));
1456 insert_insn_on_edge (insn
, e
);
1464 commit_edge_insertions ();
1465 return did_something
;
1469 /* Subroutines of life analysis. */
1471 /* Allocate the permanent data structures that represent the results
1472 of life analysis. Not static since used also for stupid life analysis. */
1475 allocate_bb_life_data ()
1479 for (i
= 0; i
< n_basic_blocks
; i
++)
1481 basic_block bb
= BASIC_BLOCK (i
);
1483 bb
->global_live_at_start
= OBSTACK_ALLOC_REG_SET (&flow_obstack
);
1484 bb
->global_live_at_end
= OBSTACK_ALLOC_REG_SET (&flow_obstack
);
1487 ENTRY_BLOCK_PTR
->global_live_at_end
1488 = OBSTACK_ALLOC_REG_SET (&flow_obstack
);
1489 EXIT_BLOCK_PTR
->global_live_at_start
1490 = OBSTACK_ALLOC_REG_SET (&flow_obstack
);
1492 regs_live_at_setjmp
= OBSTACK_ALLOC_REG_SET (&flow_obstack
);
1496 allocate_reg_life_data ()
1500 max_regno
= max_reg_num ();
1502 /* Recalculate the register space, in case it has grown. Old style
1503 vector oriented regsets would set regset_{size,bytes} here also. */
1504 allocate_reg_info (max_regno
, FALSE
, FALSE
);
1506 /* Reset all the data we'll collect in propagate_block and its
1508 for (i
= 0; i
< max_regno
; i
++)
1512 REG_N_DEATHS (i
) = 0;
1513 REG_N_CALLS_CROSSED (i
) = 0;
1514 REG_LIVE_LENGTH (i
) = 0;
1515 REG_BASIC_BLOCK (i
) = REG_BLOCK_UNKNOWN
;
1519 /* Delete dead instructions for propagate_block. */
1522 propagate_block_delete_insn (insn
)
1525 rtx inote
= find_reg_note (insn
, REG_LABEL
, NULL_RTX
);
1527 /* If the insn referred to a label, and that label was attached to
1528 an ADDR_VEC, it's safe to delete the ADDR_VEC. In fact, it's
1529 pretty much mandatory to delete it, because the ADDR_VEC may be
1530 referencing labels that no longer exist.
1532 INSN may reference a deleted label, particularly when a jump
1533 table has been optimized into a direct jump. There's no
1534 real good way to fix up the reference to the deleted label
1535 when the label is deleted, so we just allow it here.
1537 After dead code elimination is complete, we do search for
1538 any REG_LABEL notes which reference deleted labels as a
1541 if (inote
&& GET_CODE (inote
) == CODE_LABEL
)
1543 rtx label
= XEXP (inote
, 0);
1546 /* The label may be forced if it has been put in the constant
1547 pool. If that is the only use we must discard the table
1548 jump following it, but not the label itself. */
1549 if (LABEL_NUSES (label
) == 1 + LABEL_PRESERVE_P (label
)
1550 && (next
= next_nonnote_insn (label
)) != NULL
1551 && GET_CODE (next
) == JUMP_INSN
1552 && (GET_CODE (PATTERN (next
)) == ADDR_VEC
1553 || GET_CODE (PATTERN (next
)) == ADDR_DIFF_VEC
))
1555 rtx pat
= PATTERN (next
);
1556 int diff_vec_p
= GET_CODE (pat
) == ADDR_DIFF_VEC
;
1557 int len
= XVECLEN (pat
, diff_vec_p
);
1560 for (i
= 0; i
< len
; i
++)
1561 LABEL_NUSES (XEXP (XVECEXP (pat
, diff_vec_p
, i
), 0))--;
1563 delete_insn_and_edges (next
);
1568 delete_insn_and_edges (insn
);
1572 /* Delete dead libcalls for propagate_block. Return the insn
1573 before the libcall. */
1576 propagate_block_delete_libcall ( insn
, note
)
1579 rtx first
= XEXP (note
, 0);
1580 rtx before
= PREV_INSN (first
);
1582 delete_insn_chain_and_edges (first
, insn
);
1587 /* Update the life-status of regs for one insn. Return the previous insn. */
1590 propagate_one_insn (pbi
, insn
)
1591 struct propagate_block_info
*pbi
;
1594 rtx prev
= PREV_INSN (insn
);
1595 int flags
= pbi
->flags
;
1596 int insn_is_dead
= 0;
1597 int libcall_is_dead
= 0;
1601 if (! INSN_P (insn
))
1604 note
= find_reg_note (insn
, REG_RETVAL
, NULL_RTX
);
1605 if (flags
& PROP_SCAN_DEAD_CODE
)
1607 insn_is_dead
= insn_dead_p (pbi
, PATTERN (insn
), 0, REG_NOTES (insn
));
1608 libcall_is_dead
= (insn_is_dead
&& note
!= 0
1609 && libcall_dead_p (pbi
, note
, insn
));
1612 /* If an instruction consists of just dead store(s) on final pass,
1614 if ((flags
& PROP_KILL_DEAD_CODE
) && insn_is_dead
)
1616 /* If we're trying to delete a prologue or epilogue instruction
1617 that isn't flagged as possibly being dead, something is wrong.
1618 But if we are keeping the stack pointer depressed, we might well
1619 be deleting insns that are used to compute the amount to update
1620 it by, so they are fine. */
1621 if (reload_completed
1622 && !(TREE_CODE (TREE_TYPE (current_function_decl
)) == FUNCTION_TYPE
1623 && (TYPE_RETURNS_STACK_DEPRESSED
1624 (TREE_TYPE (current_function_decl
))))
1625 && (((HAVE_epilogue
|| HAVE_prologue
)
1626 && prologue_epilogue_contains (insn
))
1627 || (HAVE_sibcall_epilogue
1628 && sibcall_epilogue_contains (insn
)))
1629 && find_reg_note (insn
, REG_MAYBE_DEAD
, NULL_RTX
) == 0)
1630 fatal_insn ("Attempt to delete prologue/epilogue insn:", insn
);
1632 /* Record sets. Do this even for dead instructions, since they
1633 would have killed the values if they hadn't been deleted. */
1634 mark_set_regs (pbi
, PATTERN (insn
), insn
);
1636 /* CC0 is now known to be dead. Either this insn used it,
1637 in which case it doesn't anymore, or clobbered it,
1638 so the next insn can't use it. */
1641 if (libcall_is_dead
)
1642 prev
= propagate_block_delete_libcall ( insn
, note
);
1644 propagate_block_delete_insn (insn
);
1649 /* See if this is an increment or decrement that can be merged into
1650 a following memory address. */
1653 rtx x
= single_set (insn
);
1655 /* Does this instruction increment or decrement a register? */
1656 if ((flags
& PROP_AUTOINC
)
1658 && GET_CODE (SET_DEST (x
)) == REG
1659 && (GET_CODE (SET_SRC (x
)) == PLUS
1660 || GET_CODE (SET_SRC (x
)) == MINUS
)
1661 && XEXP (SET_SRC (x
), 0) == SET_DEST (x
)
1662 && GET_CODE (XEXP (SET_SRC (x
), 1)) == CONST_INT
1663 /* Ok, look for a following memory ref we can combine with.
1664 If one is found, change the memory ref to a PRE_INC
1665 or PRE_DEC, cancel this insn, and return 1.
1666 Return 0 if nothing has been done. */
1667 && try_pre_increment_1 (pbi
, insn
))
1670 #endif /* AUTO_INC_DEC */
1672 CLEAR_REG_SET (pbi
->new_set
);
1674 /* If this is not the final pass, and this insn is copying the value of
1675 a library call and it's dead, don't scan the insns that perform the
1676 library call, so that the call's arguments are not marked live. */
1677 if (libcall_is_dead
)
1679 /* Record the death of the dest reg. */
1680 mark_set_regs (pbi
, PATTERN (insn
), insn
);
1682 insn
= XEXP (note
, 0);
1683 return PREV_INSN (insn
);
1685 else if (GET_CODE (PATTERN (insn
)) == SET
1686 && SET_DEST (PATTERN (insn
)) == stack_pointer_rtx
1687 && GET_CODE (SET_SRC (PATTERN (insn
))) == PLUS
1688 && XEXP (SET_SRC (PATTERN (insn
)), 0) == stack_pointer_rtx
1689 && GET_CODE (XEXP (SET_SRC (PATTERN (insn
)), 1)) == CONST_INT
)
1690 /* We have an insn to pop a constant amount off the stack.
1691 (Such insns use PLUS regardless of the direction of the stack,
1692 and any insn to adjust the stack by a constant is always a pop.)
1693 These insns, if not dead stores, have no effect on life. */
1698 /* Any regs live at the time of a call instruction must not go
1699 in a register clobbered by calls. Find all regs now live and
1700 record this for them. */
1702 if (GET_CODE (insn
) == CALL_INSN
&& (flags
& PROP_REG_INFO
))
1703 EXECUTE_IF_SET_IN_REG_SET (pbi
->reg_live
, 0, i
,
1704 { REG_N_CALLS_CROSSED (i
)++; });
1706 /* Record sets. Do this even for dead instructions, since they
1707 would have killed the values if they hadn't been deleted. */
1708 mark_set_regs (pbi
, PATTERN (insn
), insn
);
1710 if (GET_CODE (insn
) == CALL_INSN
)
1716 if (GET_CODE (PATTERN (insn
)) == COND_EXEC
)
1717 cond
= COND_EXEC_TEST (PATTERN (insn
));
1719 /* Non-constant calls clobber memory. */
1720 if (! CONST_OR_PURE_CALL_P (insn
))
1722 free_EXPR_LIST_list (&pbi
->mem_set_list
);
1723 pbi
->mem_set_list_len
= 0;
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. */
1735 for (i
= 0; i
< FIRST_PSEUDO_REGISTER
; i
++)
1736 if (TEST_HARD_REG_BIT (regs_invalidated_by_call
, i
))
1738 /* We do not want REG_UNUSED notes for these registers. */
1739 mark_set_1 (pbi
, CLOBBER
, gen_rtx_REG (reg_raw_mode
[i
], i
),
1741 pbi
->flags
& ~(PROP_DEATH_NOTES
| PROP_REG_INFO
));
1745 /* If an insn doesn't use CC0, it becomes dead since we assume
1746 that every insn clobbers it. So show it dead here;
1747 mark_used_regs will set it live if it is referenced. */
1752 mark_used_regs (pbi
, PATTERN (insn
), NULL_RTX
, insn
);
1753 if ((flags
& PROP_EQUAL_NOTES
)
1754 && ((note
= find_reg_note (insn
, REG_EQUAL
, NULL_RTX
))
1755 || (note
= find_reg_note (insn
, REG_EQUIV
, NULL_RTX
))))
1756 mark_used_regs (pbi
, XEXP (note
, 0), NULL_RTX
, insn
);
1758 /* Sometimes we may have inserted something before INSN (such as a move)
1759 when we make an auto-inc. So ensure we will scan those insns. */
1761 prev
= PREV_INSN (insn
);
1764 if (! insn_is_dead
&& GET_CODE (insn
) == CALL_INSN
)
1770 if (GET_CODE (PATTERN (insn
)) == COND_EXEC
)
1771 cond
= COND_EXEC_TEST (PATTERN (insn
));
1773 /* Calls use their arguments. */
1774 for (note
= CALL_INSN_FUNCTION_USAGE (insn
);
1776 note
= XEXP (note
, 1))
1777 if (GET_CODE (XEXP (note
, 0)) == USE
)
1778 mark_used_regs (pbi
, XEXP (XEXP (note
, 0), 0),
1781 /* The stack ptr is used (honorarily) by a CALL insn. */
1782 SET_REGNO_REG_SET (pbi
->reg_live
, STACK_POINTER_REGNUM
);
1784 /* Calls may also reference any of the global registers,
1785 so they are made live. */
1786 for (i
= 0; i
< FIRST_PSEUDO_REGISTER
; i
++)
1788 mark_used_reg (pbi
, gen_rtx_REG (reg_raw_mode
[i
], i
),
1793 /* On final pass, update counts of how many insns in which each reg
1795 if (flags
& PROP_REG_INFO
)
1796 EXECUTE_IF_SET_IN_REG_SET (pbi
->reg_live
, 0, i
,
1797 { REG_LIVE_LENGTH (i
)++; });
1802 /* Initialize a propagate_block_info struct for public consumption.
1803 Note that the structure itself is opaque to this file, but that
1804 the user can use the regsets provided here. */
1806 struct propagate_block_info
*
1807 init_propagate_block_info (bb
, live
, local_set
, cond_local_set
, flags
)
1809 regset live
, local_set
, cond_local_set
;
1812 struct propagate_block_info
*pbi
= xmalloc (sizeof (*pbi
));
1815 pbi
->reg_live
= live
;
1816 pbi
->mem_set_list
= NULL_RTX
;
1817 pbi
->mem_set_list_len
= 0;
1818 pbi
->local_set
= local_set
;
1819 pbi
->cond_local_set
= cond_local_set
;
1823 if (flags
& (PROP_LOG_LINKS
| PROP_AUTOINC
))
1824 pbi
->reg_next_use
= (rtx
*) xcalloc (max_reg_num (), sizeof (rtx
));
1826 pbi
->reg_next_use
= NULL
;
1828 pbi
->new_set
= BITMAP_XMALLOC ();
1830 #ifdef HAVE_conditional_execution
1831 pbi
->reg_cond_dead
= splay_tree_new (splay_tree_compare_ints
, NULL
,
1832 free_reg_cond_life_info
);
1833 pbi
->reg_cond_reg
= BITMAP_XMALLOC ();
1835 /* If this block ends in a conditional branch, for each register live
1836 from one side of the branch and not the other, record the register
1837 as conditionally dead. */
1838 if (GET_CODE (bb
->end
) == JUMP_INSN
1839 && any_condjump_p (bb
->end
))
1841 regset_head diff_head
;
1842 regset diff
= INITIALIZE_REG_SET (diff_head
);
1843 basic_block bb_true
, bb_false
;
1844 rtx cond_true
, cond_false
, set_src
;
1847 /* Identify the successor blocks. */
1848 bb_true
= bb
->succ
->dest
;
1849 if (bb
->succ
->succ_next
!= NULL
)
1851 bb_false
= bb
->succ
->succ_next
->dest
;
1853 if (bb
->succ
->flags
& EDGE_FALLTHRU
)
1855 basic_block t
= bb_false
;
1859 else if (! (bb
->succ
->succ_next
->flags
& EDGE_FALLTHRU
))
1864 /* This can happen with a conditional jump to the next insn. */
1865 if (JUMP_LABEL (bb
->end
) != bb_true
->head
)
1868 /* Simplest way to do nothing. */
1872 /* Extract the condition from the branch. */
1873 set_src
= SET_SRC (pc_set (bb
->end
));
1874 cond_true
= XEXP (set_src
, 0);
1875 cond_false
= gen_rtx_fmt_ee (reverse_condition (GET_CODE (cond_true
)),
1876 GET_MODE (cond_true
), XEXP (cond_true
, 0),
1877 XEXP (cond_true
, 1));
1878 if (GET_CODE (XEXP (set_src
, 1)) == PC
)
1881 cond_false
= cond_true
;
1885 /* Compute which register lead different lives in the successors. */
1886 if (bitmap_operation (diff
, bb_true
->global_live_at_start
,
1887 bb_false
->global_live_at_start
, BITMAP_XOR
))
1889 rtx reg
= XEXP (cond_true
, 0);
1891 if (GET_CODE (reg
) == SUBREG
)
1892 reg
= SUBREG_REG (reg
);
1894 if (GET_CODE (reg
) != REG
)
1897 SET_REGNO_REG_SET (pbi
->reg_cond_reg
, REGNO (reg
));
1899 /* For each such register, mark it conditionally dead. */
1900 EXECUTE_IF_SET_IN_REG_SET
1903 struct reg_cond_life_info
*rcli
;
1906 rcli
= (struct reg_cond_life_info
*) xmalloc (sizeof (*rcli
));
1908 if (REGNO_REG_SET_P (bb_true
->global_live_at_start
, i
))
1912 rcli
->condition
= cond
;
1913 rcli
->stores
= const0_rtx
;
1914 rcli
->orig_condition
= cond
;
1916 splay_tree_insert (pbi
->reg_cond_dead
, i
,
1917 (splay_tree_value
) rcli
);
1921 FREE_REG_SET (diff
);
1925 /* If this block has no successors, any stores to the frame that aren't
1926 used later in the block are dead. So make a pass over the block
1927 recording any such that are made and show them dead at the end. We do
1928 a very conservative and simple job here. */
1930 && ! (TREE_CODE (TREE_TYPE (current_function_decl
)) == FUNCTION_TYPE
1931 && (TYPE_RETURNS_STACK_DEPRESSED
1932 (TREE_TYPE (current_function_decl
))))
1933 && (flags
& PROP_SCAN_DEAD_CODE
)
1934 && (bb
->succ
== NULL
1935 || (bb
->succ
->succ_next
== NULL
1936 && bb
->succ
->dest
== EXIT_BLOCK_PTR
1937 && ! current_function_calls_eh_return
)))
1940 for (insn
= bb
->end
; insn
!= bb
->head
; insn
= PREV_INSN (insn
))
1941 if (GET_CODE (insn
) == INSN
1942 && (set
= single_set (insn
))
1943 && GET_CODE (SET_DEST (set
)) == MEM
)
1945 rtx mem
= SET_DEST (set
);
1946 rtx canon_mem
= canon_rtx (mem
);
1948 /* This optimization is performed by faking a store to the
1949 memory at the end of the block. This doesn't work for
1950 unchanging memories because multiple stores to unchanging
1951 memory is illegal and alias analysis doesn't consider it. */
1952 if (RTX_UNCHANGING_P (canon_mem
))
1955 if (XEXP (canon_mem
, 0) == frame_pointer_rtx
1956 || (GET_CODE (XEXP (canon_mem
, 0)) == PLUS
1957 && XEXP (XEXP (canon_mem
, 0), 0) == frame_pointer_rtx
1958 && GET_CODE (XEXP (XEXP (canon_mem
, 0), 1)) == CONST_INT
))
1959 add_to_mem_set_list (pbi
, canon_mem
);
1966 /* Release a propagate_block_info struct. */
1969 free_propagate_block_info (pbi
)
1970 struct propagate_block_info
*pbi
;
1972 free_EXPR_LIST_list (&pbi
->mem_set_list
);
1974 BITMAP_XFREE (pbi
->new_set
);
1976 #ifdef HAVE_conditional_execution
1977 splay_tree_delete (pbi
->reg_cond_dead
);
1978 BITMAP_XFREE (pbi
->reg_cond_reg
);
1981 if (pbi
->reg_next_use
)
1982 free (pbi
->reg_next_use
);
1987 /* Compute the registers live at the beginning of a basic block BB from
1988 those live at the end.
1990 When called, REG_LIVE contains those live at the end. On return, it
1991 contains those live at the beginning.
1993 LOCAL_SET, if non-null, will be set with all registers killed
1994 unconditionally by this basic block.
1995 Likewise, COND_LOCAL_SET, if non-null, will be set with all registers
1996 killed conditionally by this basic block. If there is any unconditional
1997 set of a register, then the corresponding bit will be set in LOCAL_SET
1998 and cleared in COND_LOCAL_SET.
1999 It is valid for LOCAL_SET and COND_LOCAL_SET to be the same set. In this
2000 case, the resulting set will be equal to the union of the two sets that
2001 would otherwise be computed.
2003 Return non-zero if an INSN is deleted (i.e. by dead code removal). */
2006 propagate_block (bb
, live
, local_set
, cond_local_set
, flags
)
2010 regset cond_local_set
;
2013 struct propagate_block_info
*pbi
;
2017 pbi
= init_propagate_block_info (bb
, live
, local_set
, cond_local_set
, flags
);
2019 if (flags
& PROP_REG_INFO
)
2023 /* Process the regs live at the end of the block.
2024 Mark them as not local to any one basic block. */
2025 EXECUTE_IF_SET_IN_REG_SET (live
, 0, i
,
2026 { REG_BASIC_BLOCK (i
) = REG_BLOCK_GLOBAL
; });
2029 /* Scan the block an insn at a time from end to beginning. */
2032 for (insn
= bb
->end
;; insn
= prev
)
2034 /* If this is a call to `setjmp' et al, warn if any
2035 non-volatile datum is live. */
2036 if ((flags
& PROP_REG_INFO
)
2037 && GET_CODE (insn
) == CALL_INSN
2038 && find_reg_note (insn
, REG_SETJMP
, NULL
))
2039 IOR_REG_SET (regs_live_at_setjmp
, pbi
->reg_live
);
2041 prev
= propagate_one_insn (pbi
, insn
);
2042 changed
|= NEXT_INSN (prev
) != insn
;
2044 if (insn
== bb
->head
)
2048 free_propagate_block_info (pbi
);
2053 /* Return 1 if X (the body of an insn, or part of it) is just dead stores
2054 (SET expressions whose destinations are registers dead after the insn).
2055 NEEDED is the regset that says which regs are alive after the insn.
2057 Unless CALL_OK is non-zero, an insn is needed if it contains a CALL.
2059 If X is the entire body of an insn, NOTES contains the reg notes
2060 pertaining to the insn. */
2063 insn_dead_p (pbi
, x
, call_ok
, notes
)
2064 struct propagate_block_info
*pbi
;
2067 rtx notes ATTRIBUTE_UNUSED
;
2069 enum rtx_code code
= GET_CODE (x
);
2072 /* As flow is invoked after combine, we must take existing AUTO_INC
2073 expressions into account. */
2074 for (; notes
; notes
= XEXP (notes
, 1))
2076 if (REG_NOTE_KIND (notes
) == REG_INC
)
2078 int regno
= REGNO (XEXP (notes
, 0));
2080 /* Don't delete insns to set global regs. */
2081 if ((regno
< FIRST_PSEUDO_REGISTER
&& global_regs
[regno
])
2082 || REGNO_REG_SET_P (pbi
->reg_live
, regno
))
2088 /* If setting something that's a reg or part of one,
2089 see if that register's altered value will be live. */
2093 rtx r
= SET_DEST (x
);
2096 if (GET_CODE (r
) == CC0
)
2097 return ! pbi
->cc0_live
;
2100 /* A SET that is a subroutine call cannot be dead. */
2101 if (GET_CODE (SET_SRC (x
)) == CALL
)
2107 /* Don't eliminate loads from volatile memory or volatile asms. */
2108 else if (volatile_refs_p (SET_SRC (x
)))
2111 if (GET_CODE (r
) == MEM
)
2115 if (MEM_VOLATILE_P (r
) || GET_MODE (r
) == BLKmode
)
2118 canon_r
= canon_rtx (r
);
2120 /* Walk the set of memory locations we are currently tracking
2121 and see if one is an identical match to this memory location.
2122 If so, this memory write is dead (remember, we're walking
2123 backwards from the end of the block to the start). Since
2124 rtx_equal_p does not check the alias set or flags, we also
2125 must have the potential for them to conflict (anti_dependence). */
2126 for (temp
= pbi
->mem_set_list
; temp
!= 0; temp
= XEXP (temp
, 1))
2127 if (anti_dependence (r
, XEXP (temp
, 0)))
2129 rtx mem
= XEXP (temp
, 0);
2131 if (rtx_equal_p (XEXP (canon_r
, 0), XEXP (mem
, 0))
2132 && (GET_MODE_SIZE (GET_MODE (canon_r
))
2133 <= GET_MODE_SIZE (GET_MODE (mem
))))
2137 /* Check if memory reference matches an auto increment. Only
2138 post increment/decrement or modify are valid. */
2139 if (GET_MODE (mem
) == GET_MODE (r
)
2140 && (GET_CODE (XEXP (mem
, 0)) == POST_DEC
2141 || GET_CODE (XEXP (mem
, 0)) == POST_INC
2142 || GET_CODE (XEXP (mem
, 0)) == POST_MODIFY
)
2143 && GET_MODE (XEXP (mem
, 0)) == GET_MODE (r
)
2144 && rtx_equal_p (XEXP (XEXP (mem
, 0), 0), XEXP (r
, 0)))
2151 while (GET_CODE (r
) == SUBREG
2152 || GET_CODE (r
) == STRICT_LOW_PART
2153 || GET_CODE (r
) == ZERO_EXTRACT
)
2156 if (GET_CODE (r
) == REG
)
2158 int regno
= REGNO (r
);
2161 if (REGNO_REG_SET_P (pbi
->reg_live
, regno
))
2164 /* If this is a hard register, verify that subsequent
2165 words are not needed. */
2166 if (regno
< FIRST_PSEUDO_REGISTER
)
2168 int n
= HARD_REGNO_NREGS (regno
, GET_MODE (r
));
2171 if (REGNO_REG_SET_P (pbi
->reg_live
, regno
+n
))
2175 /* Don't delete insns to set global regs. */
2176 if (regno
< FIRST_PSEUDO_REGISTER
&& global_regs
[regno
])
2179 /* Make sure insns to set the stack pointer aren't deleted. */
2180 if (regno
== STACK_POINTER_REGNUM
)
2183 /* ??? These bits might be redundant with the force live bits
2184 in calculate_global_regs_live. We would delete from
2185 sequential sets; whether this actually affects real code
2186 for anything but the stack pointer I don't know. */
2187 /* Make sure insns to set the frame pointer aren't deleted. */
2188 if (regno
== FRAME_POINTER_REGNUM
2189 && (! reload_completed
|| frame_pointer_needed
))
2191 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
2192 if (regno
== HARD_FRAME_POINTER_REGNUM
2193 && (! reload_completed
|| frame_pointer_needed
))
2197 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
2198 /* Make sure insns to set arg pointer are never deleted
2199 (if the arg pointer isn't fixed, there will be a USE
2200 for it, so we can treat it normally). */
2201 if (regno
== ARG_POINTER_REGNUM
&& fixed_regs
[regno
])
2205 /* Otherwise, the set is dead. */
2211 /* If performing several activities, insn is dead if each activity
2212 is individually dead. Also, CLOBBERs and USEs can be ignored; a
2213 CLOBBER or USE that's inside a PARALLEL doesn't make the insn
2215 else if (code
== PARALLEL
)
2217 int i
= XVECLEN (x
, 0);
2219 for (i
--; i
>= 0; i
--)
2220 if (GET_CODE (XVECEXP (x
, 0, i
)) != CLOBBER
2221 && GET_CODE (XVECEXP (x
, 0, i
)) != USE
2222 && ! insn_dead_p (pbi
, XVECEXP (x
, 0, i
), call_ok
, NULL_RTX
))
2228 /* A CLOBBER of a pseudo-register that is dead serves no purpose. That
2229 is not necessarily true for hard registers. */
2230 else if (code
== CLOBBER
&& GET_CODE (XEXP (x
, 0)) == REG
2231 && REGNO (XEXP (x
, 0)) >= FIRST_PSEUDO_REGISTER
2232 && ! REGNO_REG_SET_P (pbi
->reg_live
, REGNO (XEXP (x
, 0))))
2235 /* We do not check other CLOBBER or USE here. An insn consisting of just
2236 a CLOBBER or just a USE should not be deleted. */
2240 /* If INSN is the last insn in a libcall, and assuming INSN is dead,
2241 return 1 if the entire library call is dead.
2242 This is true if INSN copies a register (hard or pseudo)
2243 and if the hard return reg of the call insn is dead.
2244 (The caller should have tested the destination of the SET inside
2245 INSN already for death.)
2247 If this insn doesn't just copy a register, then we don't
2248 have an ordinary libcall. In that case, cse could not have
2249 managed to substitute the source for the dest later on,
2250 so we can assume the libcall is dead.
2252 PBI is the block info giving pseudoregs live before this insn.
2253 NOTE is the REG_RETVAL note of the insn. */
2256 libcall_dead_p (pbi
, note
, insn
)
2257 struct propagate_block_info
*pbi
;
2261 rtx x
= single_set (insn
);
2265 rtx r
= SET_SRC (x
);
2267 if (GET_CODE (r
) == REG
)
2269 rtx call
= XEXP (note
, 0);
2273 /* Find the call insn. */
2274 while (call
!= insn
&& GET_CODE (call
) != CALL_INSN
)
2275 call
= NEXT_INSN (call
);
2277 /* If there is none, do nothing special,
2278 since ordinary death handling can understand these insns. */
2282 /* See if the hard reg holding the value is dead.
2283 If this is a PARALLEL, find the call within it. */
2284 call_pat
= PATTERN (call
);
2285 if (GET_CODE (call_pat
) == PARALLEL
)
2287 for (i
= XVECLEN (call_pat
, 0) - 1; i
>= 0; i
--)
2288 if (GET_CODE (XVECEXP (call_pat
, 0, i
)) == SET
2289 && GET_CODE (SET_SRC (XVECEXP (call_pat
, 0, i
))) == CALL
)
2292 /* This may be a library call that is returning a value
2293 via invisible pointer. Do nothing special, since
2294 ordinary death handling can understand these insns. */
2298 call_pat
= XVECEXP (call_pat
, 0, i
);
2301 return insn_dead_p (pbi
, call_pat
, 1, REG_NOTES (call
));
2307 /* Return 1 if register REGNO was used before it was set, i.e. if it is
2308 live at function entry. Don't count global register variables, variables
2309 in registers that can be used for function arg passing, or variables in
2310 fixed hard registers. */
2313 regno_uninitialized (regno
)
2316 if (n_basic_blocks
== 0
2317 || (regno
< FIRST_PSEUDO_REGISTER
2318 && (global_regs
[regno
]
2319 || fixed_regs
[regno
]
2320 || FUNCTION_ARG_REGNO_P (regno
))))
2323 return REGNO_REG_SET_P (BASIC_BLOCK (0)->global_live_at_start
, regno
);
2326 /* 1 if register REGNO was alive at a place where `setjmp' was called
2327 and was set more than once or is an argument.
2328 Such regs may be clobbered by `longjmp'. */
2331 regno_clobbered_at_setjmp (regno
)
2334 if (n_basic_blocks
== 0)
2337 return ((REG_N_SETS (regno
) > 1
2338 || REGNO_REG_SET_P (BASIC_BLOCK (0)->global_live_at_start
, regno
))
2339 && REGNO_REG_SET_P (regs_live_at_setjmp
, regno
));
2342 /* Add MEM to PBI->MEM_SET_LIST. MEM should be canonical. Respect the
2343 maximal list size; look for overlaps in mode and select the largest. */
2345 add_to_mem_set_list (pbi
, mem
)
2346 struct propagate_block_info
*pbi
;
2351 /* We don't know how large a BLKmode store is, so we must not
2352 take them into consideration. */
2353 if (GET_MODE (mem
) == BLKmode
)
2356 for (i
= pbi
->mem_set_list
; i
; i
= XEXP (i
, 1))
2358 rtx e
= XEXP (i
, 0);
2359 if (rtx_equal_p (XEXP (mem
, 0), XEXP (e
, 0)))
2361 if (GET_MODE_SIZE (GET_MODE (mem
)) > GET_MODE_SIZE (GET_MODE (e
)))
2364 /* If we must store a copy of the mem, we can just modify
2365 the mode of the stored copy. */
2366 if (pbi
->flags
& PROP_AUTOINC
)
2367 PUT_MODE (e
, GET_MODE (mem
));
2376 if (pbi
->mem_set_list_len
< MAX_MEM_SET_LIST_LEN
)
2379 /* Store a copy of mem, otherwise the address may be
2380 scrogged by find_auto_inc. */
2381 if (pbi
->flags
& PROP_AUTOINC
)
2382 mem
= shallow_copy_rtx (mem
);
2384 pbi
->mem_set_list
= alloc_EXPR_LIST (0, mem
, pbi
->mem_set_list
);
2385 pbi
->mem_set_list_len
++;
2389 /* INSN references memory, possibly using autoincrement addressing modes.
2390 Find any entries on the mem_set_list that need to be invalidated due
2391 to an address change. */
2394 invalidate_mems_from_autoinc (pbi
, insn
)
2395 struct propagate_block_info
*pbi
;
2398 rtx note
= REG_NOTES (insn
);
2399 for (note
= REG_NOTES (insn
); note
; note
= XEXP (note
, 1))
2400 if (REG_NOTE_KIND (note
) == REG_INC
)
2401 invalidate_mems_from_set (pbi
, XEXP (note
, 0));
2404 /* EXP is a REG. Remove any dependent entries from pbi->mem_set_list. */
2407 invalidate_mems_from_set (pbi
, exp
)
2408 struct propagate_block_info
*pbi
;
2411 rtx temp
= pbi
->mem_set_list
;
2412 rtx prev
= NULL_RTX
;
2417 next
= XEXP (temp
, 1);
2418 if (reg_overlap_mentioned_p (exp
, XEXP (temp
, 0)))
2420 /* Splice this entry out of the list. */
2422 XEXP (prev
, 1) = next
;
2424 pbi
->mem_set_list
= next
;
2425 free_EXPR_LIST_node (temp
);
2426 pbi
->mem_set_list_len
--;
2434 /* Process the registers that are set within X. Their bits are set to
2435 1 in the regset DEAD, because they are dead prior to this insn.
2437 If INSN is nonzero, it is the insn being processed.
2439 FLAGS is the set of operations to perform. */
2442 mark_set_regs (pbi
, x
, insn
)
2443 struct propagate_block_info
*pbi
;
2446 rtx cond
= NULL_RTX
;
2451 for (link
= REG_NOTES (insn
); link
; link
= XEXP (link
, 1))
2453 if (REG_NOTE_KIND (link
) == REG_INC
)
2454 mark_set_1 (pbi
, SET
, XEXP (link
, 0),
2455 (GET_CODE (x
) == COND_EXEC
2456 ? COND_EXEC_TEST (x
) : NULL_RTX
),
2460 switch (code
= GET_CODE (x
))
2464 mark_set_1 (pbi
, code
, SET_DEST (x
), cond
, insn
, pbi
->flags
);
2468 cond
= COND_EXEC_TEST (x
);
2469 x
= COND_EXEC_CODE (x
);
2476 for (i
= XVECLEN (x
, 0) - 1; i
>= 0; i
--)
2478 rtx sub
= XVECEXP (x
, 0, i
);
2479 switch (code
= GET_CODE (sub
))
2482 if (cond
!= NULL_RTX
)
2485 cond
= COND_EXEC_TEST (sub
);
2486 sub
= COND_EXEC_CODE (sub
);
2487 if (GET_CODE (sub
) != SET
&& GET_CODE (sub
) != CLOBBER
)
2493 mark_set_1 (pbi
, code
, SET_DEST (sub
), cond
, insn
, pbi
->flags
);
2508 /* Process a single set, which appears in INSN. REG (which may not
2509 actually be a REG, it may also be a SUBREG, PARALLEL, etc.) is
2510 being set using the CODE (which may be SET, CLOBBER, or COND_EXEC).
2511 If the set is conditional (because it appear in a COND_EXEC), COND
2512 will be the condition. */
2515 mark_set_1 (pbi
, code
, reg
, cond
, insn
, flags
)
2516 struct propagate_block_info
*pbi
;
2518 rtx reg
, cond
, insn
;
2521 int regno_first
= -1, regno_last
= -1;
2522 unsigned long not_dead
= 0;
2525 /* Modifying just one hardware register of a multi-reg value or just a
2526 byte field of a register does not mean the value from before this insn
2527 is now dead. Of course, if it was dead after it's unused now. */
2529 switch (GET_CODE (reg
))
2532 /* Some targets place small structures in registers for return values of
2533 functions. We have to detect this case specially here to get correct
2534 flow information. */
2535 for (i
= XVECLEN (reg
, 0) - 1; i
>= 0; i
--)
2536 if (XEXP (XVECEXP (reg
, 0, i
), 0) != 0)
2537 mark_set_1 (pbi
, code
, XEXP (XVECEXP (reg
, 0, i
), 0), cond
, insn
,
2543 case STRICT_LOW_PART
:
2544 /* ??? Assumes STRICT_LOW_PART not used on multi-word registers. */
2546 reg
= XEXP (reg
, 0);
2547 while (GET_CODE (reg
) == SUBREG
2548 || GET_CODE (reg
) == ZERO_EXTRACT
2549 || GET_CODE (reg
) == SIGN_EXTRACT
2550 || GET_CODE (reg
) == STRICT_LOW_PART
);
2551 if (GET_CODE (reg
) == MEM
)
2553 not_dead
= (unsigned long) REGNO_REG_SET_P (pbi
->reg_live
, REGNO (reg
));
2557 regno_last
= regno_first
= REGNO (reg
);
2558 if (regno_first
< FIRST_PSEUDO_REGISTER
)
2559 regno_last
+= HARD_REGNO_NREGS (regno_first
, GET_MODE (reg
)) - 1;
2563 if (GET_CODE (SUBREG_REG (reg
)) == REG
)
2565 enum machine_mode outer_mode
= GET_MODE (reg
);
2566 enum machine_mode inner_mode
= GET_MODE (SUBREG_REG (reg
));
2568 /* Identify the range of registers affected. This is moderately
2569 tricky for hard registers. See alter_subreg. */
2571 regno_last
= regno_first
= REGNO (SUBREG_REG (reg
));
2572 if (regno_first
< FIRST_PSEUDO_REGISTER
)
2574 regno_first
+= subreg_regno_offset (regno_first
, inner_mode
,
2577 regno_last
= (regno_first
2578 + HARD_REGNO_NREGS (regno_first
, outer_mode
) - 1);
2580 /* Since we've just adjusted the register number ranges, make
2581 sure REG matches. Otherwise some_was_live will be clear
2582 when it shouldn't have been, and we'll create incorrect
2583 REG_UNUSED notes. */
2584 reg
= gen_rtx_REG (outer_mode
, regno_first
);
2588 /* If the number of words in the subreg is less than the number
2589 of words in the full register, we have a well-defined partial
2590 set. Otherwise the high bits are undefined.
2592 This is only really applicable to pseudos, since we just took
2593 care of multi-word hard registers. */
2594 if (((GET_MODE_SIZE (outer_mode
)
2595 + UNITS_PER_WORD
- 1) / UNITS_PER_WORD
)
2596 < ((GET_MODE_SIZE (inner_mode
)
2597 + UNITS_PER_WORD
- 1) / UNITS_PER_WORD
))
2598 not_dead
= (unsigned long) REGNO_REG_SET_P (pbi
->reg_live
,
2601 reg
= SUBREG_REG (reg
);
2605 reg
= SUBREG_REG (reg
);
2612 /* If this set is a MEM, then it kills any aliased writes.
2613 If this set is a REG, then it kills any MEMs which use the reg. */
2614 if (optimize
&& (flags
& PROP_SCAN_DEAD_CODE
))
2616 if (GET_CODE (reg
) == REG
)
2617 invalidate_mems_from_set (pbi
, reg
);
2619 /* If the memory reference had embedded side effects (autoincrement
2620 address modes. Then we may need to kill some entries on the
2622 if (insn
&& GET_CODE (reg
) == MEM
)
2623 invalidate_mems_from_autoinc (pbi
, insn
);
2625 if (GET_CODE (reg
) == MEM
&& ! side_effects_p (reg
)
2626 /* ??? With more effort we could track conditional memory life. */
2628 /* There are no REG_INC notes for SP, so we can't assume we'll see
2629 everything that invalidates it. To be safe, don't eliminate any
2630 stores though SP; none of them should be redundant anyway. */
2631 && ! reg_mentioned_p (stack_pointer_rtx
, reg
))
2632 add_to_mem_set_list (pbi
, canon_rtx (reg
));
2635 if (GET_CODE (reg
) == REG
2636 && ! (regno_first
== FRAME_POINTER_REGNUM
2637 && (! reload_completed
|| frame_pointer_needed
))
2638 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
2639 && ! (regno_first
== HARD_FRAME_POINTER_REGNUM
2640 && (! reload_completed
|| frame_pointer_needed
))
2642 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
2643 && ! (regno_first
== ARG_POINTER_REGNUM
&& fixed_regs
[regno_first
])
2647 int some_was_live
= 0, some_was_dead
= 0;
2649 for (i
= regno_first
; i
<= regno_last
; ++i
)
2651 int needed_regno
= REGNO_REG_SET_P (pbi
->reg_live
, i
);
2654 /* Order of the set operation matters here since both
2655 sets may be the same. */
2656 CLEAR_REGNO_REG_SET (pbi
->cond_local_set
, i
);
2657 if (cond
!= NULL_RTX
2658 && ! REGNO_REG_SET_P (pbi
->local_set
, i
))
2659 SET_REGNO_REG_SET (pbi
->cond_local_set
, i
);
2661 SET_REGNO_REG_SET (pbi
->local_set
, i
);
2663 if (code
!= CLOBBER
)
2664 SET_REGNO_REG_SET (pbi
->new_set
, i
);
2666 some_was_live
|= needed_regno
;
2667 some_was_dead
|= ! needed_regno
;
2670 #ifdef HAVE_conditional_execution
2671 /* Consider conditional death in deciding that the register needs
2673 if (some_was_live
&& ! not_dead
2674 /* The stack pointer is never dead. Well, not strictly true,
2675 but it's very difficult to tell from here. Hopefully
2676 combine_stack_adjustments will fix up the most egregious
2678 && regno_first
!= STACK_POINTER_REGNUM
)
2680 for (i
= regno_first
; i
<= regno_last
; ++i
)
2681 if (! mark_regno_cond_dead (pbi
, i
, cond
))
2682 not_dead
|= ((unsigned long) 1) << (i
- regno_first
);
2686 /* Additional data to record if this is the final pass. */
2687 if (flags
& (PROP_LOG_LINKS
| PROP_REG_INFO
2688 | PROP_DEATH_NOTES
| PROP_AUTOINC
))
2691 int blocknum
= pbi
->bb
->index
;
2694 if (flags
& (PROP_LOG_LINKS
| PROP_AUTOINC
))
2696 y
= pbi
->reg_next_use
[regno_first
];
2698 /* The next use is no longer next, since a store intervenes. */
2699 for (i
= regno_first
; i
<= regno_last
; ++i
)
2700 pbi
->reg_next_use
[i
] = 0;
2703 if (flags
& PROP_REG_INFO
)
2705 for (i
= regno_first
; i
<= regno_last
; ++i
)
2707 /* Count (weighted) references, stores, etc. This counts a
2708 register twice if it is modified, but that is correct. */
2709 REG_N_SETS (i
) += 1;
2710 REG_N_REFS (i
) += 1;
2711 REG_FREQ (i
) += REG_FREQ_FROM_BB (pbi
->bb
);
2713 /* The insns where a reg is live are normally counted
2714 elsewhere, but we want the count to include the insn
2715 where the reg is set, and the normal counting mechanism
2716 would not count it. */
2717 REG_LIVE_LENGTH (i
) += 1;
2720 /* If this is a hard reg, record this function uses the reg. */
2721 if (regno_first
< FIRST_PSEUDO_REGISTER
)
2723 for (i
= regno_first
; i
<= regno_last
; i
++)
2724 regs_ever_live
[i
] = 1;
2728 /* Keep track of which basic blocks each reg appears in. */
2729 if (REG_BASIC_BLOCK (regno_first
) == REG_BLOCK_UNKNOWN
)
2730 REG_BASIC_BLOCK (regno_first
) = blocknum
;
2731 else if (REG_BASIC_BLOCK (regno_first
) != blocknum
)
2732 REG_BASIC_BLOCK (regno_first
) = REG_BLOCK_GLOBAL
;
2736 if (! some_was_dead
)
2738 if (flags
& PROP_LOG_LINKS
)
2740 /* Make a logical link from the next following insn
2741 that uses this register, back to this insn.
2742 The following insns have already been processed.
2744 We don't build a LOG_LINK for hard registers containing
2745 in ASM_OPERANDs. If these registers get replaced,
2746 we might wind up changing the semantics of the insn,
2747 even if reload can make what appear to be valid
2748 assignments later. */
2749 if (y
&& (BLOCK_NUM (y
) == blocknum
)
2750 && (regno_first
>= FIRST_PSEUDO_REGISTER
2751 || asm_noperands (PATTERN (y
)) < 0))
2752 LOG_LINKS (y
) = alloc_INSN_LIST (insn
, LOG_LINKS (y
));
2757 else if (! some_was_live
)
2759 if (flags
& PROP_REG_INFO
)
2760 REG_N_DEATHS (regno_first
) += 1;
2762 if (flags
& PROP_DEATH_NOTES
)
2764 /* Note that dead stores have already been deleted
2765 when possible. If we get here, we have found a
2766 dead store that cannot be eliminated (because the
2767 same insn does something useful). Indicate this
2768 by marking the reg being set as dying here. */
2770 = alloc_EXPR_LIST (REG_UNUSED
, reg
, REG_NOTES (insn
));
2775 if (flags
& PROP_DEATH_NOTES
)
2777 /* This is a case where we have a multi-word hard register
2778 and some, but not all, of the words of the register are
2779 needed in subsequent insns. Write REG_UNUSED notes
2780 for those parts that were not needed. This case should
2783 for (i
= regno_first
; i
<= regno_last
; ++i
)
2784 if (! REGNO_REG_SET_P (pbi
->reg_live
, i
))
2786 = alloc_EXPR_LIST (REG_UNUSED
,
2787 gen_rtx_REG (reg_raw_mode
[i
], i
),
2793 /* Mark the register as being dead. */
2795 /* The stack pointer is never dead. Well, not strictly true,
2796 but it's very difficult to tell from here. Hopefully
2797 combine_stack_adjustments will fix up the most egregious
2799 && regno_first
!= STACK_POINTER_REGNUM
)
2801 for (i
= regno_first
; i
<= regno_last
; ++i
)
2802 if (!(not_dead
& (((unsigned long) 1) << (i
- regno_first
))))
2803 CLEAR_REGNO_REG_SET (pbi
->reg_live
, i
);
2806 else if (GET_CODE (reg
) == REG
)
2808 if (flags
& (PROP_LOG_LINKS
| PROP_AUTOINC
))
2809 pbi
->reg_next_use
[regno_first
] = 0;
2812 /* If this is the last pass and this is a SCRATCH, show it will be dying
2813 here and count it. */
2814 else if (GET_CODE (reg
) == SCRATCH
)
2816 if (flags
& PROP_DEATH_NOTES
)
2818 = alloc_EXPR_LIST (REG_UNUSED
, reg
, REG_NOTES (insn
));
2822 #ifdef HAVE_conditional_execution
2823 /* Mark REGNO conditionally dead.
2824 Return true if the register is now unconditionally dead. */
2827 mark_regno_cond_dead (pbi
, regno
, cond
)
2828 struct propagate_block_info
*pbi
;
2832 /* If this is a store to a predicate register, the value of the
2833 predicate is changing, we don't know that the predicate as seen
2834 before is the same as that seen after. Flush all dependent
2835 conditions from reg_cond_dead. This will make all such
2836 conditionally live registers unconditionally live. */
2837 if (REGNO_REG_SET_P (pbi
->reg_cond_reg
, regno
))
2838 flush_reg_cond_reg (pbi
, regno
);
2840 /* If this is an unconditional store, remove any conditional
2841 life that may have existed. */
2842 if (cond
== NULL_RTX
)
2843 splay_tree_remove (pbi
->reg_cond_dead
, regno
);
2846 splay_tree_node node
;
2847 struct reg_cond_life_info
*rcli
;
2850 /* Otherwise this is a conditional set. Record that fact.
2851 It may have been conditionally used, or there may be a
2852 subsequent set with a complimentary condition. */
2854 node
= splay_tree_lookup (pbi
->reg_cond_dead
, regno
);
2857 /* The register was unconditionally live previously.
2858 Record the current condition as the condition under
2859 which it is dead. */
2860 rcli
= (struct reg_cond_life_info
*) xmalloc (sizeof (*rcli
));
2861 rcli
->condition
= cond
;
2862 rcli
->stores
= cond
;
2863 rcli
->orig_condition
= const0_rtx
;
2864 splay_tree_insert (pbi
->reg_cond_dead
, regno
,
2865 (splay_tree_value
) rcli
);
2867 SET_REGNO_REG_SET (pbi
->reg_cond_reg
, REGNO (XEXP (cond
, 0)));
2869 /* Not unconditionally dead. */
2874 /* The register was conditionally live previously.
2875 Add the new condition to the old. */
2876 rcli
= (struct reg_cond_life_info
*) node
->value
;
2877 ncond
= rcli
->condition
;
2878 ncond
= ior_reg_cond (ncond
, cond
, 1);
2879 if (rcli
->stores
== const0_rtx
)
2880 rcli
->stores
= cond
;
2881 else if (rcli
->stores
!= const1_rtx
)
2882 rcli
->stores
= ior_reg_cond (rcli
->stores
, cond
, 1);
2884 /* If the register is now unconditionally dead, remove the entry
2885 in the splay_tree. A register is unconditionally dead if the
2886 dead condition ncond is true. A register is also unconditionally
2887 dead if the sum of all conditional stores is an unconditional
2888 store (stores is true), and the dead condition is identically the
2889 same as the original dead condition initialized at the end of
2890 the block. This is a pointer compare, not an rtx_equal_p
2892 if (ncond
== const1_rtx
2893 || (ncond
== rcli
->orig_condition
&& rcli
->stores
== const1_rtx
))
2894 splay_tree_remove (pbi
->reg_cond_dead
, regno
);
2897 rcli
->condition
= ncond
;
2899 SET_REGNO_REG_SET (pbi
->reg_cond_reg
, REGNO (XEXP (cond
, 0)));
2901 /* Not unconditionally dead. */
2910 /* Called from splay_tree_delete for pbi->reg_cond_life. */
2913 free_reg_cond_life_info (value
)
2914 splay_tree_value value
;
2916 struct reg_cond_life_info
*rcli
= (struct reg_cond_life_info
*) value
;
2920 /* Helper function for flush_reg_cond_reg. */
2923 flush_reg_cond_reg_1 (node
, data
)
2924 splay_tree_node node
;
2927 struct reg_cond_life_info
*rcli
;
2928 int *xdata
= (int *) data
;
2929 unsigned int regno
= xdata
[0];
2931 /* Don't need to search if last flushed value was farther on in
2932 the in-order traversal. */
2933 if (xdata
[1] >= (int) node
->key
)
2936 /* Splice out portions of the expression that refer to regno. */
2937 rcli
= (struct reg_cond_life_info
*) node
->value
;
2938 rcli
->condition
= elim_reg_cond (rcli
->condition
, regno
);
2939 if (rcli
->stores
!= const0_rtx
&& rcli
->stores
!= const1_rtx
)
2940 rcli
->stores
= elim_reg_cond (rcli
->stores
, regno
);
2942 /* If the entire condition is now false, signal the node to be removed. */
2943 if (rcli
->condition
== const0_rtx
)
2945 xdata
[1] = node
->key
;
2948 else if (rcli
->condition
== const1_rtx
)
2954 /* Flush all (sub) expressions referring to REGNO from REG_COND_LIVE. */
2957 flush_reg_cond_reg (pbi
, regno
)
2958 struct propagate_block_info
*pbi
;
2965 while (splay_tree_foreach (pbi
->reg_cond_dead
,
2966 flush_reg_cond_reg_1
, pair
) == -1)
2967 splay_tree_remove (pbi
->reg_cond_dead
, pair
[1]);
2969 CLEAR_REGNO_REG_SET (pbi
->reg_cond_reg
, regno
);
2972 /* Logical arithmetic on predicate conditions. IOR, NOT and AND.
2973 For ior/and, the ADD flag determines whether we want to add the new
2974 condition X to the old one unconditionally. If it is zero, we will
2975 only return a new expression if X allows us to simplify part of
2976 OLD, otherwise we return NULL to the caller.
2977 If ADD is nonzero, we will return a new condition in all cases. The
2978 toplevel caller of one of these functions should always pass 1 for
2982 ior_reg_cond (old
, x
, add
)
2988 if (GET_RTX_CLASS (GET_CODE (old
)) == '<')
2990 if (GET_RTX_CLASS (GET_CODE (x
)) == '<'
2991 && REVERSE_CONDEXEC_PREDICATES_P (GET_CODE (x
), GET_CODE (old
))
2992 && REGNO (XEXP (x
, 0)) == REGNO (XEXP (old
, 0)))
2994 if (GET_CODE (x
) == GET_CODE (old
)
2995 && REGNO (XEXP (x
, 0)) == REGNO (XEXP (old
, 0)))
2999 return gen_rtx_IOR (0, old
, x
);
3002 switch (GET_CODE (old
))
3005 op0
= ior_reg_cond (XEXP (old
, 0), x
, 0);
3006 op1
= ior_reg_cond (XEXP (old
, 1), x
, 0);
3007 if (op0
!= NULL
|| op1
!= NULL
)
3009 if (op0
== const0_rtx
)
3010 return op1
? op1
: gen_rtx_IOR (0, XEXP (old
, 1), x
);
3011 if (op1
== const0_rtx
)
3012 return op0
? op0
: gen_rtx_IOR (0, XEXP (old
, 0), x
);
3013 if (op0
== const1_rtx
|| op1
== const1_rtx
)
3016 op0
= gen_rtx_IOR (0, XEXP (old
, 0), x
);
3017 else if (rtx_equal_p (x
, op0
))
3018 /* (x | A) | x ~ (x | A). */
3021 op1
= gen_rtx_IOR (0, XEXP (old
, 1), x
);
3022 else if (rtx_equal_p (x
, op1
))
3023 /* (A | x) | x ~ (A | x). */
3025 return gen_rtx_IOR (0, op0
, op1
);
3029 return gen_rtx_IOR (0, old
, x
);
3032 op0
= ior_reg_cond (XEXP (old
, 0), x
, 0);
3033 op1
= ior_reg_cond (XEXP (old
, 1), x
, 0);
3034 if (op0
!= NULL
|| op1
!= NULL
)
3036 if (op0
== const1_rtx
)
3037 return op1
? op1
: gen_rtx_IOR (0, XEXP (old
, 1), x
);
3038 if (op1
== const1_rtx
)
3039 return op0
? op0
: gen_rtx_IOR (0, XEXP (old
, 0), x
);
3040 if (op0
== const0_rtx
|| op1
== const0_rtx
)
3043 op0
= gen_rtx_IOR (0, XEXP (old
, 0), x
);
3044 else if (rtx_equal_p (x
, op0
))
3045 /* (x & A) | x ~ x. */
3048 op1
= gen_rtx_IOR (0, XEXP (old
, 1), x
);
3049 else if (rtx_equal_p (x
, op1
))
3050 /* (A & x) | x ~ x. */
3052 return gen_rtx_AND (0, op0
, op1
);
3056 return gen_rtx_IOR (0, old
, x
);
3059 op0
= and_reg_cond (XEXP (old
, 0), not_reg_cond (x
), 0);
3061 return not_reg_cond (op0
);
3064 return gen_rtx_IOR (0, old
, x
);
3075 enum rtx_code x_code
;
3077 if (x
== const0_rtx
)
3079 else if (x
== const1_rtx
)
3081 x_code
= GET_CODE (x
);
3084 if (GET_RTX_CLASS (x_code
) == '<'
3085 && GET_CODE (XEXP (x
, 0)) == REG
)
3087 if (XEXP (x
, 1) != const0_rtx
)
3090 return gen_rtx_fmt_ee (reverse_condition (x_code
),
3091 VOIDmode
, XEXP (x
, 0), const0_rtx
);
3093 return gen_rtx_NOT (0, x
);
3097 and_reg_cond (old
, x
, add
)
3103 if (GET_RTX_CLASS (GET_CODE (old
)) == '<')
3105 if (GET_RTX_CLASS (GET_CODE (x
)) == '<'
3106 && GET_CODE (x
) == reverse_condition (GET_CODE (old
))
3107 && REGNO (XEXP (x
, 0)) == REGNO (XEXP (old
, 0)))
3109 if (GET_CODE (x
) == GET_CODE (old
)
3110 && REGNO (XEXP (x
, 0)) == REGNO (XEXP (old
, 0)))
3114 return gen_rtx_AND (0, old
, x
);
3117 switch (GET_CODE (old
))
3120 op0
= and_reg_cond (XEXP (old
, 0), x
, 0);
3121 op1
= and_reg_cond (XEXP (old
, 1), x
, 0);
3122 if (op0
!= NULL
|| op1
!= NULL
)
3124 if (op0
== const0_rtx
)
3125 return op1
? op1
: gen_rtx_AND (0, XEXP (old
, 1), x
);
3126 if (op1
== const0_rtx
)
3127 return op0
? op0
: gen_rtx_AND (0, XEXP (old
, 0), x
);
3128 if (op0
== const1_rtx
|| op1
== const1_rtx
)
3131 op0
= gen_rtx_AND (0, XEXP (old
, 0), x
);
3132 else if (rtx_equal_p (x
, op0
))
3133 /* (x | A) & x ~ x. */
3136 op1
= gen_rtx_AND (0, XEXP (old
, 1), x
);
3137 else if (rtx_equal_p (x
, op1
))
3138 /* (A | x) & x ~ x. */
3140 return gen_rtx_IOR (0, op0
, op1
);
3144 return gen_rtx_AND (0, old
, x
);
3147 op0
= and_reg_cond (XEXP (old
, 0), x
, 0);
3148 op1
= and_reg_cond (XEXP (old
, 1), x
, 0);
3149 if (op0
!= NULL
|| op1
!= NULL
)
3151 if (op0
== const1_rtx
)
3152 return op1
? op1
: gen_rtx_AND (0, XEXP (old
, 1), x
);
3153 if (op1
== const1_rtx
)
3154 return op0
? op0
: gen_rtx_AND (0, XEXP (old
, 0), x
);
3155 if (op0
== const0_rtx
|| op1
== const0_rtx
)
3158 op0
= gen_rtx_AND (0, XEXP (old
, 0), x
);
3159 else if (rtx_equal_p (x
, op0
))
3160 /* (x & A) & x ~ (x & A). */
3163 op1
= gen_rtx_AND (0, XEXP (old
, 1), x
);
3164 else if (rtx_equal_p (x
, op1
))
3165 /* (A & x) & x ~ (A & x). */
3167 return gen_rtx_AND (0, op0
, op1
);
3171 return gen_rtx_AND (0, old
, x
);
3174 op0
= ior_reg_cond (XEXP (old
, 0), not_reg_cond (x
), 0);
3176 return not_reg_cond (op0
);
3179 return gen_rtx_AND (0, old
, x
);
3186 /* Given a condition X, remove references to reg REGNO and return the
3187 new condition. The removal will be done so that all conditions
3188 involving REGNO are considered to evaluate to false. This function
3189 is used when the value of REGNO changes. */
3192 elim_reg_cond (x
, regno
)
3198 if (GET_RTX_CLASS (GET_CODE (x
)) == '<')
3200 if (REGNO (XEXP (x
, 0)) == regno
)
3205 switch (GET_CODE (x
))
3208 op0
= elim_reg_cond (XEXP (x
, 0), regno
);
3209 op1
= elim_reg_cond (XEXP (x
, 1), regno
);
3210 if (op0
== const0_rtx
|| op1
== const0_rtx
)
3212 if (op0
== const1_rtx
)
3214 if (op1
== const1_rtx
)
3216 if (op0
== XEXP (x
, 0) && op1
== XEXP (x
, 1))
3218 return gen_rtx_AND (0, op0
, op1
);
3221 op0
= elim_reg_cond (XEXP (x
, 0), regno
);
3222 op1
= elim_reg_cond (XEXP (x
, 1), regno
);
3223 if (op0
== const1_rtx
|| op1
== const1_rtx
)
3225 if (op0
== const0_rtx
)
3227 if (op1
== const0_rtx
)
3229 if (op0
== XEXP (x
, 0) && op1
== XEXP (x
, 1))
3231 return gen_rtx_IOR (0, op0
, op1
);
3234 op0
= elim_reg_cond (XEXP (x
, 0), regno
);
3235 if (op0
== const0_rtx
)
3237 if (op0
== const1_rtx
)
3239 if (op0
!= XEXP (x
, 0))
3240 return not_reg_cond (op0
);
3247 #endif /* HAVE_conditional_execution */
3251 /* Try to substitute the auto-inc expression INC as the address inside
3252 MEM which occurs in INSN. Currently, the address of MEM is an expression
3253 involving INCR_REG, and INCR is the next use of INCR_REG; it is an insn
3254 that has a single set whose source is a PLUS of INCR_REG and something
3258 attempt_auto_inc (pbi
, inc
, insn
, mem
, incr
, incr_reg
)
3259 struct propagate_block_info
*pbi
;
3260 rtx inc
, insn
, mem
, incr
, incr_reg
;
3262 int regno
= REGNO (incr_reg
);
3263 rtx set
= single_set (incr
);
3264 rtx q
= SET_DEST (set
);
3265 rtx y
= SET_SRC (set
);
3266 int opnum
= XEXP (y
, 0) == incr_reg
? 0 : 1;
3268 /* Make sure this reg appears only once in this insn. */
3269 if (count_occurrences (PATTERN (insn
), incr_reg
, 1) != 1)
3272 if (dead_or_set_p (incr
, incr_reg
)
3273 /* Mustn't autoinc an eliminable register. */
3274 && (regno
>= FIRST_PSEUDO_REGISTER
3275 || ! TEST_HARD_REG_BIT (elim_reg_set
, regno
)))
3277 /* This is the simple case. Try to make the auto-inc. If
3278 we can't, we are done. Otherwise, we will do any
3279 needed updates below. */
3280 if (! validate_change (insn
, &XEXP (mem
, 0), inc
, 0))
3283 else if (GET_CODE (q
) == REG
3284 /* PREV_INSN used here to check the semi-open interval
3286 && ! reg_used_between_p (q
, PREV_INSN (insn
), incr
)
3287 /* We must also check for sets of q as q may be
3288 a call clobbered hard register and there may
3289 be a call between PREV_INSN (insn) and incr. */
3290 && ! reg_set_between_p (q
, PREV_INSN (insn
), incr
))
3292 /* We have *p followed sometime later by q = p+size.
3293 Both p and q must be live afterward,
3294 and q is not used between INSN and its assignment.
3295 Change it to q = p, ...*q..., q = q+size.
3296 Then fall into the usual case. */
3300 emit_move_insn (q
, incr_reg
);
3301 insns
= get_insns ();
3304 /* If we can't make the auto-inc, or can't make the
3305 replacement into Y, exit. There's no point in making
3306 the change below if we can't do the auto-inc and doing
3307 so is not correct in the pre-inc case. */
3310 validate_change (insn
, &XEXP (mem
, 0), inc
, 1);
3311 validate_change (incr
, &XEXP (y
, opnum
), q
, 1);
3312 if (! apply_change_group ())
3315 /* We now know we'll be doing this change, so emit the
3316 new insn(s) and do the updates. */
3317 emit_insns_before (insns
, insn
);
3319 if (pbi
->bb
->head
== insn
)
3320 pbi
->bb
->head
= insns
;
3322 /* INCR will become a NOTE and INSN won't contain a
3323 use of INCR_REG. If a use of INCR_REG was just placed in
3324 the insn before INSN, make that the next use.
3325 Otherwise, invalidate it. */
3326 if (GET_CODE (PREV_INSN (insn
)) == INSN
3327 && GET_CODE (PATTERN (PREV_INSN (insn
))) == SET
3328 && SET_SRC (PATTERN (PREV_INSN (insn
))) == incr_reg
)
3329 pbi
->reg_next_use
[regno
] = PREV_INSN (insn
);
3331 pbi
->reg_next_use
[regno
] = 0;
3336 /* REGNO is now used in INCR which is below INSN, but
3337 it previously wasn't live here. If we don't mark
3338 it as live, we'll put a REG_DEAD note for it
3339 on this insn, which is incorrect. */
3340 SET_REGNO_REG_SET (pbi
->reg_live
, regno
);
3342 /* If there are any calls between INSN and INCR, show
3343 that REGNO now crosses them. */
3344 for (temp
= insn
; temp
!= incr
; temp
= NEXT_INSN (temp
))
3345 if (GET_CODE (temp
) == CALL_INSN
)
3346 REG_N_CALLS_CROSSED (regno
)++;
3348 /* Invalidate alias info for Q since we just changed its value. */
3349 clear_reg_alias_info (q
);
3354 /* If we haven't returned, it means we were able to make the
3355 auto-inc, so update the status. First, record that this insn
3356 has an implicit side effect. */
3358 REG_NOTES (insn
) = alloc_EXPR_LIST (REG_INC
, incr_reg
, REG_NOTES (insn
));
3360 /* Modify the old increment-insn to simply copy
3361 the already-incremented value of our register. */
3362 if (! validate_change (incr
, &SET_SRC (set
), incr_reg
, 0))
3365 /* If that makes it a no-op (copying the register into itself) delete
3366 it so it won't appear to be a "use" and a "set" of this
3368 if (REGNO (SET_DEST (set
)) == REGNO (incr_reg
))
3370 /* If the original source was dead, it's dead now. */
3373 while ((note
= find_reg_note (incr
, REG_DEAD
, NULL_RTX
)) != NULL_RTX
)
3375 remove_note (incr
, note
);
3376 if (XEXP (note
, 0) != incr_reg
)
3377 CLEAR_REGNO_REG_SET (pbi
->reg_live
, REGNO (XEXP (note
, 0)));
3380 PUT_CODE (incr
, NOTE
);
3381 NOTE_LINE_NUMBER (incr
) = NOTE_INSN_DELETED
;
3382 NOTE_SOURCE_FILE (incr
) = 0;
3385 if (regno
>= FIRST_PSEUDO_REGISTER
)
3387 /* Count an extra reference to the reg. When a reg is
3388 incremented, spilling it is worse, so we want to make
3389 that less likely. */
3390 REG_FREQ (regno
) += REG_FREQ_FROM_BB (pbi
->bb
);
3392 /* Count the increment as a setting of the register,
3393 even though it isn't a SET in rtl. */
3394 REG_N_SETS (regno
)++;
3398 /* X is a MEM found in INSN. See if we can convert it into an auto-increment
3402 find_auto_inc (pbi
, x
, insn
)
3403 struct propagate_block_info
*pbi
;
3407 rtx addr
= XEXP (x
, 0);
3408 HOST_WIDE_INT offset
= 0;
3409 rtx set
, y
, incr
, inc_val
;
3411 int size
= GET_MODE_SIZE (GET_MODE (x
));
3413 if (GET_CODE (insn
) == JUMP_INSN
)
3416 /* Here we detect use of an index register which might be good for
3417 postincrement, postdecrement, preincrement, or predecrement. */
3419 if (GET_CODE (addr
) == PLUS
&& GET_CODE (XEXP (addr
, 1)) == CONST_INT
)
3420 offset
= INTVAL (XEXP (addr
, 1)), addr
= XEXP (addr
, 0);
3422 if (GET_CODE (addr
) != REG
)
3425 regno
= REGNO (addr
);
3427 /* Is the next use an increment that might make auto-increment? */
3428 incr
= pbi
->reg_next_use
[regno
];
3429 if (incr
== 0 || BLOCK_NUM (incr
) != BLOCK_NUM (insn
))
3431 set
= single_set (incr
);
3432 if (set
== 0 || GET_CODE (set
) != SET
)
3436 if (GET_CODE (y
) != PLUS
)
3439 if (REG_P (XEXP (y
, 0)) && REGNO (XEXP (y
, 0)) == REGNO (addr
))
3440 inc_val
= XEXP (y
, 1);
3441 else if (REG_P (XEXP (y
, 1)) && REGNO (XEXP (y
, 1)) == REGNO (addr
))
3442 inc_val
= XEXP (y
, 0);
3446 if (GET_CODE (inc_val
) == CONST_INT
)
3448 if (HAVE_POST_INCREMENT
3449 && (INTVAL (inc_val
) == size
&& offset
== 0))
3450 attempt_auto_inc (pbi
, gen_rtx_POST_INC (Pmode
, addr
), insn
, x
,
3452 else if (HAVE_POST_DECREMENT
3453 && (INTVAL (inc_val
) == -size
&& offset
== 0))
3454 attempt_auto_inc (pbi
, gen_rtx_POST_DEC (Pmode
, addr
), insn
, x
,
3456 else if (HAVE_PRE_INCREMENT
3457 && (INTVAL (inc_val
) == size
&& offset
== size
))
3458 attempt_auto_inc (pbi
, gen_rtx_PRE_INC (Pmode
, addr
), insn
, x
,
3460 else if (HAVE_PRE_DECREMENT
3461 && (INTVAL (inc_val
) == -size
&& offset
== -size
))
3462 attempt_auto_inc (pbi
, gen_rtx_PRE_DEC (Pmode
, addr
), insn
, x
,
3464 else if (HAVE_POST_MODIFY_DISP
&& offset
== 0)
3465 attempt_auto_inc (pbi
, gen_rtx_POST_MODIFY (Pmode
, addr
,
3466 gen_rtx_PLUS (Pmode
,
3469 insn
, x
, incr
, addr
);
3471 else if (GET_CODE (inc_val
) == REG
3472 && ! reg_set_between_p (inc_val
, PREV_INSN (insn
),
3476 if (HAVE_POST_MODIFY_REG
&& offset
== 0)
3477 attempt_auto_inc (pbi
, gen_rtx_POST_MODIFY (Pmode
, addr
,
3478 gen_rtx_PLUS (Pmode
,
3481 insn
, x
, incr
, addr
);
3485 #endif /* AUTO_INC_DEC */
3488 mark_used_reg (pbi
, reg
, cond
, insn
)
3489 struct propagate_block_info
*pbi
;
3491 rtx cond ATTRIBUTE_UNUSED
;
3494 unsigned int regno_first
, regno_last
, i
;
3495 int some_was_live
, some_was_dead
, some_not_set
;
3497 regno_last
= regno_first
= REGNO (reg
);
3498 if (regno_first
< FIRST_PSEUDO_REGISTER
)
3499 regno_last
+= HARD_REGNO_NREGS (regno_first
, GET_MODE (reg
)) - 1;
3501 /* Find out if any of this register is live after this instruction. */
3502 some_was_live
= some_was_dead
= 0;
3503 for (i
= regno_first
; i
<= regno_last
; ++i
)
3505 int needed_regno
= REGNO_REG_SET_P (pbi
->reg_live
, i
);
3506 some_was_live
|= needed_regno
;
3507 some_was_dead
|= ! needed_regno
;
3510 /* Find out if any of the register was set this insn. */
3512 for (i
= regno_first
; i
<= regno_last
; ++i
)
3513 some_not_set
|= ! REGNO_REG_SET_P (pbi
->new_set
, i
);
3515 if (pbi
->flags
& (PROP_LOG_LINKS
| PROP_AUTOINC
))
3517 /* Record where each reg is used, so when the reg is set we know
3518 the next insn that uses it. */
3519 pbi
->reg_next_use
[regno_first
] = insn
;
3522 if (pbi
->flags
& PROP_REG_INFO
)
3524 if (regno_first
< FIRST_PSEUDO_REGISTER
)
3526 /* If this is a register we are going to try to eliminate,
3527 don't mark it live here. If we are successful in
3528 eliminating it, it need not be live unless it is used for
3529 pseudos, in which case it will have been set live when it
3530 was allocated to the pseudos. If the register will not
3531 be eliminated, reload will set it live at that point.
3533 Otherwise, record that this function uses this register. */
3534 /* ??? The PPC backend tries to "eliminate" on the pic
3535 register to itself. This should be fixed. In the mean
3536 time, hack around it. */
3538 if (! (TEST_HARD_REG_BIT (elim_reg_set
, regno_first
)
3539 && (regno_first
== FRAME_POINTER_REGNUM
3540 || regno_first
== ARG_POINTER_REGNUM
)))
3541 for (i
= regno_first
; i
<= regno_last
; ++i
)
3542 regs_ever_live
[i
] = 1;
3546 /* Keep track of which basic block each reg appears in. */
3548 int blocknum
= pbi
->bb
->index
;
3549 if (REG_BASIC_BLOCK (regno_first
) == REG_BLOCK_UNKNOWN
)
3550 REG_BASIC_BLOCK (regno_first
) = blocknum
;
3551 else if (REG_BASIC_BLOCK (regno_first
) != blocknum
)
3552 REG_BASIC_BLOCK (regno_first
) = REG_BLOCK_GLOBAL
;
3554 /* Count (weighted) number of uses of each reg. */
3555 REG_FREQ (regno_first
) += REG_FREQ_FROM_BB (pbi
->bb
);
3556 REG_N_REFS (regno_first
)++;
3560 /* Record and count the insns in which a reg dies. If it is used in
3561 this insn and was dead below the insn then it dies in this insn.
3562 If it was set in this insn, we do not make a REG_DEAD note;
3563 likewise if we already made such a note. */
3564 if ((pbi
->flags
& (PROP_DEATH_NOTES
| PROP_REG_INFO
))
3568 /* Check for the case where the register dying partially
3569 overlaps the register set by this insn. */
3570 if (regno_first
!= regno_last
)
3571 for (i
= regno_first
; i
<= regno_last
; ++i
)
3572 some_was_live
|= REGNO_REG_SET_P (pbi
->new_set
, i
);
3574 /* If none of the words in X is needed, make a REG_DEAD note.
3575 Otherwise, we must make partial REG_DEAD notes. */
3576 if (! some_was_live
)
3578 if ((pbi
->flags
& PROP_DEATH_NOTES
)
3579 && ! find_regno_note (insn
, REG_DEAD
, regno_first
))
3581 = alloc_EXPR_LIST (REG_DEAD
, reg
, REG_NOTES (insn
));
3583 if (pbi
->flags
& PROP_REG_INFO
)
3584 REG_N_DEATHS (regno_first
)++;
3588 /* Don't make a REG_DEAD note for a part of a register
3589 that is set in the insn. */
3590 for (i
= regno_first
; i
<= regno_last
; ++i
)
3591 if (! REGNO_REG_SET_P (pbi
->reg_live
, i
)
3592 && ! dead_or_set_regno_p (insn
, i
))
3594 = alloc_EXPR_LIST (REG_DEAD
,
3595 gen_rtx_REG (reg_raw_mode
[i
], i
),
3600 /* Mark the register as being live. */
3601 for (i
= regno_first
; i
<= regno_last
; ++i
)
3603 SET_REGNO_REG_SET (pbi
->reg_live
, i
);
3605 #ifdef HAVE_conditional_execution
3606 /* If this is a conditional use, record that fact. If it is later
3607 conditionally set, we'll know to kill the register. */
3608 if (cond
!= NULL_RTX
)
3610 splay_tree_node node
;
3611 struct reg_cond_life_info
*rcli
;
3616 node
= splay_tree_lookup (pbi
->reg_cond_dead
, i
);
3619 /* The register was unconditionally live previously.
3620 No need to do anything. */
3624 /* The register was conditionally live previously.
3625 Subtract the new life cond from the old death cond. */
3626 rcli
= (struct reg_cond_life_info
*) node
->value
;
3627 ncond
= rcli
->condition
;
3628 ncond
= and_reg_cond (ncond
, not_reg_cond (cond
), 1);
3630 /* If the register is now unconditionally live,
3631 remove the entry in the splay_tree. */
3632 if (ncond
== const0_rtx
)
3633 splay_tree_remove (pbi
->reg_cond_dead
, i
);
3636 rcli
->condition
= ncond
;
3637 SET_REGNO_REG_SET (pbi
->reg_cond_reg
,
3638 REGNO (XEXP (cond
, 0)));
3644 /* The register was not previously live at all. Record
3645 the condition under which it is still dead. */
3646 rcli
= (struct reg_cond_life_info
*) xmalloc (sizeof (*rcli
));
3647 rcli
->condition
= not_reg_cond (cond
);
3648 rcli
->stores
= const0_rtx
;
3649 rcli
->orig_condition
= const0_rtx
;
3650 splay_tree_insert (pbi
->reg_cond_dead
, i
,
3651 (splay_tree_value
) rcli
);
3653 SET_REGNO_REG_SET (pbi
->reg_cond_reg
, REGNO (XEXP (cond
, 0)));
3656 else if (some_was_live
)
3658 /* The register may have been conditionally live previously, but
3659 is now unconditionally live. Remove it from the conditionally
3660 dead list, so that a conditional set won't cause us to think
3662 splay_tree_remove (pbi
->reg_cond_dead
, i
);
3668 /* Scan expression X and store a 1-bit in NEW_LIVE for each reg it uses.
3669 This is done assuming the registers needed from X are those that
3670 have 1-bits in PBI->REG_LIVE.
3672 INSN is the containing instruction. If INSN is dead, this function
3676 mark_used_regs (pbi
, x
, cond
, insn
)
3677 struct propagate_block_info
*pbi
;
3682 int flags
= pbi
->flags
;
3687 code
= GET_CODE (x
);
3708 /* If we are clobbering a MEM, mark any registers inside the address
3710 if (GET_CODE (XEXP (x
, 0)) == MEM
)
3711 mark_used_regs (pbi
, XEXP (XEXP (x
, 0), 0), cond
, insn
);
3715 /* Don't bother watching stores to mems if this is not the
3716 final pass. We'll not be deleting dead stores this round. */
3717 if (optimize
&& (flags
& PROP_SCAN_DEAD_CODE
))
3719 /* Invalidate the data for the last MEM stored, but only if MEM is
3720 something that can be stored into. */
3721 if (GET_CODE (XEXP (x
, 0)) == SYMBOL_REF
3722 && CONSTANT_POOL_ADDRESS_P (XEXP (x
, 0)))
3723 /* Needn't clear the memory set list. */
3727 rtx temp
= pbi
->mem_set_list
;
3728 rtx prev
= NULL_RTX
;
3733 next
= XEXP (temp
, 1);
3734 if (anti_dependence (XEXP (temp
, 0), x
))
3736 /* Splice temp out of the list. */
3738 XEXP (prev
, 1) = next
;
3740 pbi
->mem_set_list
= next
;
3741 free_EXPR_LIST_node (temp
);
3742 pbi
->mem_set_list_len
--;
3750 /* If the memory reference had embedded side effects (autoincrement
3751 address modes. Then we may need to kill some entries on the
3754 invalidate_mems_from_autoinc (pbi
, insn
);
3758 if (flags
& PROP_AUTOINC
)
3759 find_auto_inc (pbi
, x
, insn
);
3764 #ifdef CLASS_CANNOT_CHANGE_MODE
3765 if (GET_CODE (SUBREG_REG (x
)) == REG
3766 && REGNO (SUBREG_REG (x
)) >= FIRST_PSEUDO_REGISTER
3767 && CLASS_CANNOT_CHANGE_MODE_P (GET_MODE (x
),
3768 GET_MODE (SUBREG_REG (x
))))
3769 REG_CHANGES_MODE (REGNO (SUBREG_REG (x
))) = 1;
3772 /* While we're here, optimize this case. */
3774 if (GET_CODE (x
) != REG
)
3779 /* See a register other than being set => mark it as needed. */
3780 mark_used_reg (pbi
, x
, cond
, insn
);
3785 rtx testreg
= SET_DEST (x
);
3788 /* If storing into MEM, don't show it as being used. But do
3789 show the address as being used. */
3790 if (GET_CODE (testreg
) == MEM
)
3793 if (flags
& PROP_AUTOINC
)
3794 find_auto_inc (pbi
, testreg
, insn
);
3796 mark_used_regs (pbi
, XEXP (testreg
, 0), cond
, insn
);
3797 mark_used_regs (pbi
, SET_SRC (x
), cond
, insn
);
3801 /* Storing in STRICT_LOW_PART is like storing in a reg
3802 in that this SET might be dead, so ignore it in TESTREG.
3803 but in some other ways it is like using the reg.
3805 Storing in a SUBREG or a bit field is like storing the entire
3806 register in that if the register's value is not used
3807 then this SET is not needed. */
3808 while (GET_CODE (testreg
) == STRICT_LOW_PART
3809 || GET_CODE (testreg
) == ZERO_EXTRACT
3810 || GET_CODE (testreg
) == SIGN_EXTRACT
3811 || GET_CODE (testreg
) == SUBREG
)
3813 #ifdef CLASS_CANNOT_CHANGE_MODE
3814 if (GET_CODE (testreg
) == SUBREG
3815 && GET_CODE (SUBREG_REG (testreg
)) == REG
3816 && REGNO (SUBREG_REG (testreg
)) >= FIRST_PSEUDO_REGISTER
3817 && CLASS_CANNOT_CHANGE_MODE_P (GET_MODE (SUBREG_REG (testreg
)),
3818 GET_MODE (testreg
)))
3819 REG_CHANGES_MODE (REGNO (SUBREG_REG (testreg
))) = 1;
3822 /* Modifying a single register in an alternate mode
3823 does not use any of the old value. But these other
3824 ways of storing in a register do use the old value. */
3825 if (GET_CODE (testreg
) == SUBREG
3826 && !((REG_BYTES (SUBREG_REG (testreg
))
3827 + UNITS_PER_WORD
- 1) / UNITS_PER_WORD
3828 > (REG_BYTES (testreg
)
3829 + UNITS_PER_WORD
- 1) / UNITS_PER_WORD
))
3834 testreg
= XEXP (testreg
, 0);
3837 /* If this is a store into a register or group of registers,
3838 recursively scan the value being stored. */
3840 if ((GET_CODE (testreg
) == PARALLEL
3841 && GET_MODE (testreg
) == BLKmode
)
3842 || (GET_CODE (testreg
) == REG
3843 && (regno
= REGNO (testreg
),
3844 ! (regno
== FRAME_POINTER_REGNUM
3845 && (! reload_completed
|| frame_pointer_needed
)))
3846 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
3847 && ! (regno
== HARD_FRAME_POINTER_REGNUM
3848 && (! reload_completed
|| frame_pointer_needed
))
3850 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
3851 && ! (regno
== ARG_POINTER_REGNUM
&& fixed_regs
[regno
])
3856 mark_used_regs (pbi
, SET_DEST (x
), cond
, insn
);
3857 mark_used_regs (pbi
, SET_SRC (x
), cond
, insn
);
3864 case UNSPEC_VOLATILE
:
3868 /* Traditional and volatile asm instructions must be considered to use
3869 and clobber all hard registers, all pseudo-registers and all of
3870 memory. So must TRAP_IF and UNSPEC_VOLATILE operations.
3872 Consider for instance a volatile asm that changes the fpu rounding
3873 mode. An insn should not be moved across this even if it only uses
3874 pseudo-regs because it might give an incorrectly rounded result.
3876 ?!? Unfortunately, marking all hard registers as live causes massive
3877 problems for the register allocator and marking all pseudos as live
3878 creates mountains of uninitialized variable warnings.
3880 So for now, just clear the memory set list and mark any regs
3881 we can find in ASM_OPERANDS as used. */
3882 if (code
!= ASM_OPERANDS
|| MEM_VOLATILE_P (x
))
3884 free_EXPR_LIST_list (&pbi
->mem_set_list
);
3885 pbi
->mem_set_list_len
= 0;
3888 /* For all ASM_OPERANDS, we must traverse the vector of input operands.
3889 We can not just fall through here since then we would be confused
3890 by the ASM_INPUT rtx inside ASM_OPERANDS, which do not indicate
3891 traditional asms unlike their normal usage. */
3892 if (code
== ASM_OPERANDS
)
3896 for (j
= 0; j
< ASM_OPERANDS_INPUT_LENGTH (x
); j
++)
3897 mark_used_regs (pbi
, ASM_OPERANDS_INPUT (x
, j
), cond
, insn
);
3903 if (cond
!= NULL_RTX
)
3906 mark_used_regs (pbi
, COND_EXEC_TEST (x
), NULL_RTX
, insn
);
3908 cond
= COND_EXEC_TEST (x
);
3909 x
= COND_EXEC_CODE (x
);
3913 /* We _do_not_ want to scan operands of phi nodes. Operands of
3914 a phi function are evaluated only when control reaches this
3915 block along a particular edge. Therefore, regs that appear
3916 as arguments to phi should not be added to the global live at
3924 /* Recursively scan the operands of this expression. */
3927 const char * const fmt
= GET_RTX_FORMAT (code
);
3930 for (i
= GET_RTX_LENGTH (code
) - 1; i
>= 0; i
--)
3934 /* Tail recursive case: save a function call level. */
3940 mark_used_regs (pbi
, XEXP (x
, i
), cond
, insn
);
3942 else if (fmt
[i
] == 'E')
3945 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
3946 mark_used_regs (pbi
, XVECEXP (x
, i
, j
), cond
, insn
);
3955 try_pre_increment_1 (pbi
, insn
)
3956 struct propagate_block_info
*pbi
;
3959 /* Find the next use of this reg. If in same basic block,
3960 make it do pre-increment or pre-decrement if appropriate. */
3961 rtx x
= single_set (insn
);
3962 HOST_WIDE_INT amount
= ((GET_CODE (SET_SRC (x
)) == PLUS
? 1 : -1)
3963 * INTVAL (XEXP (SET_SRC (x
), 1)));
3964 int regno
= REGNO (SET_DEST (x
));
3965 rtx y
= pbi
->reg_next_use
[regno
];
3967 && SET_DEST (x
) != stack_pointer_rtx
3968 && BLOCK_NUM (y
) == BLOCK_NUM (insn
)
3969 /* Don't do this if the reg dies, or gets set in y; a standard addressing
3970 mode would be better. */
3971 && ! dead_or_set_p (y
, SET_DEST (x
))
3972 && try_pre_increment (y
, SET_DEST (x
), amount
))
3974 /* We have found a suitable auto-increment and already changed
3975 insn Y to do it. So flush this increment instruction. */
3976 propagate_block_delete_insn (insn
);
3978 /* Count a reference to this reg for the increment insn we are
3979 deleting. When a reg is incremented, spilling it is worse,
3980 so we want to make that less likely. */
3981 if (regno
>= FIRST_PSEUDO_REGISTER
)
3983 REG_FREQ (regno
) += REG_FREQ_FROM_BB (pbi
->bb
);
3984 REG_N_SETS (regno
)++;
3987 /* Flush any remembered memories depending on the value of
3988 the incremented register. */
3989 invalidate_mems_from_set (pbi
, SET_DEST (x
));
3996 /* Try to change INSN so that it does pre-increment or pre-decrement
3997 addressing on register REG in order to add AMOUNT to REG.
3998 AMOUNT is negative for pre-decrement.
3999 Returns 1 if the change could be made.
4000 This checks all about the validity of the result of modifying INSN. */
4003 try_pre_increment (insn
, reg
, amount
)
4005 HOST_WIDE_INT amount
;
4009 /* Nonzero if we can try to make a pre-increment or pre-decrement.
4010 For example, addl $4,r1; movl (r1),... can become movl +(r1),... */
4012 /* Nonzero if we can try to make a post-increment or post-decrement.
4013 For example, addl $4,r1; movl -4(r1),... can become movl (r1)+,...
4014 It is possible for both PRE_OK and POST_OK to be nonzero if the machine
4015 supports both pre-inc and post-inc, or both pre-dec and post-dec. */
4018 /* Nonzero if the opportunity actually requires post-inc or post-dec. */
4021 /* From the sign of increment, see which possibilities are conceivable
4022 on this target machine. */
4023 if (HAVE_PRE_INCREMENT
&& amount
> 0)
4025 if (HAVE_POST_INCREMENT
&& amount
> 0)
4028 if (HAVE_PRE_DECREMENT
&& amount
< 0)
4030 if (HAVE_POST_DECREMENT
&& amount
< 0)
4033 if (! (pre_ok
|| post_ok
))
4036 /* It is not safe to add a side effect to a jump insn
4037 because if the incremented register is spilled and must be reloaded
4038 there would be no way to store the incremented value back in memory. */
4040 if (GET_CODE (insn
) == JUMP_INSN
)
4045 use
= find_use_as_address (PATTERN (insn
), reg
, 0);
4046 if (post_ok
&& (use
== 0 || use
== (rtx
) (size_t) 1))
4048 use
= find_use_as_address (PATTERN (insn
), reg
, -amount
);
4052 if (use
== 0 || use
== (rtx
) (size_t) 1)
4055 if (GET_MODE_SIZE (GET_MODE (use
)) != (amount
> 0 ? amount
: - amount
))
4058 /* See if this combination of instruction and addressing mode exists. */
4059 if (! validate_change (insn
, &XEXP (use
, 0),
4060 gen_rtx_fmt_e (amount
> 0
4061 ? (do_post
? POST_INC
: PRE_INC
)
4062 : (do_post
? POST_DEC
: PRE_DEC
),
4066 /* Record that this insn now has an implicit side effect on X. */
4067 REG_NOTES (insn
) = alloc_EXPR_LIST (REG_INC
, reg
, REG_NOTES (insn
));
4071 #endif /* AUTO_INC_DEC */
4073 /* Find the place in the rtx X where REG is used as a memory address.
4074 Return the MEM rtx that so uses it.
4075 If PLUSCONST is nonzero, search instead for a memory address equivalent to
4076 (plus REG (const_int PLUSCONST)).
4078 If such an address does not appear, return 0.
4079 If REG appears more than once, or is used other than in such an address,
4083 find_use_as_address (x
, reg
, plusconst
)
4086 HOST_WIDE_INT plusconst
;
4088 enum rtx_code code
= GET_CODE (x
);
4089 const char * const fmt
= GET_RTX_FORMAT (code
);
4094 if (code
== MEM
&& XEXP (x
, 0) == reg
&& plusconst
== 0)
4097 if (code
== MEM
&& GET_CODE (XEXP (x
, 0)) == PLUS
4098 && XEXP (XEXP (x
, 0), 0) == reg
4099 && GET_CODE (XEXP (XEXP (x
, 0), 1)) == CONST_INT
4100 && INTVAL (XEXP (XEXP (x
, 0), 1)) == plusconst
)
4103 if (code
== SIGN_EXTRACT
|| code
== ZERO_EXTRACT
)
4105 /* If REG occurs inside a MEM used in a bit-field reference,
4106 that is unacceptable. */
4107 if (find_use_as_address (XEXP (x
, 0), reg
, 0) != 0)
4108 return (rtx
) (size_t) 1;
4112 return (rtx
) (size_t) 1;
4114 for (i
= GET_RTX_LENGTH (code
) - 1; i
>= 0; i
--)
4118 tem
= find_use_as_address (XEXP (x
, i
), reg
, plusconst
);
4122 return (rtx
) (size_t) 1;
4124 else if (fmt
[i
] == 'E')
4127 for (j
= XVECLEN (x
, i
) - 1; j
>= 0; j
--)
4129 tem
= find_use_as_address (XVECEXP (x
, i
, j
), reg
, plusconst
);
4133 return (rtx
) (size_t) 1;
4141 /* Write information about registers and basic blocks into FILE.
4142 This is part of making a debugging dump. */
4145 dump_regset (r
, outf
)
4152 fputs (" (nil)", outf
);
4156 EXECUTE_IF_SET_IN_REG_SET (r
, 0, i
,
4158 fprintf (outf
, " %d", i
);
4159 if (i
< FIRST_PSEUDO_REGISTER
)
4160 fprintf (outf
, " [%s]",
4165 /* Print a human-reaable representation of R on the standard error
4166 stream. This function is designed to be used from within the
4173 dump_regset (r
, stderr
);
4174 putc ('\n', stderr
);
4177 /* Recompute register set/reference counts immediately prior to register
4180 This avoids problems with set/reference counts changing to/from values
4181 which have special meanings to the register allocators.
4183 Additionally, the reference counts are the primary component used by the
4184 register allocators to prioritize pseudos for allocation to hard regs.
4185 More accurate reference counts generally lead to better register allocation.
4187 F is the first insn to be scanned.
4189 LOOP_STEP denotes how much loop_depth should be incremented per
4190 loop nesting level in order to increase the ref count more for
4191 references in a loop.
4193 It might be worthwhile to update REG_LIVE_LENGTH, REG_BASIC_BLOCK and
4194 possibly other information which is used by the register allocators. */
4197 recompute_reg_usage (f
, loop_step
)
4198 rtx f ATTRIBUTE_UNUSED
;
4199 int loop_step ATTRIBUTE_UNUSED
;
4201 allocate_reg_life_data ();
4202 update_life_info (NULL
, UPDATE_LIFE_LOCAL
, PROP_REG_INFO
);
4205 /* Optionally removes all the REG_DEAD and REG_UNUSED notes from a set of
4206 blocks. If BLOCKS is NULL, assume the universal set. Returns a count
4207 of the number of registers that died. */
4210 count_or_remove_death_notes (blocks
, kill
)
4216 for (i
= n_basic_blocks
- 1; i
>= 0; --i
)
4221 if (blocks
&& ! TEST_BIT (blocks
, i
))
4224 bb
= BASIC_BLOCK (i
);
4226 for (insn
= bb
->head
;; insn
= NEXT_INSN (insn
))
4230 rtx
*pprev
= ®_NOTES (insn
);
4235 switch (REG_NOTE_KIND (link
))
4238 if (GET_CODE (XEXP (link
, 0)) == REG
)
4240 rtx reg
= XEXP (link
, 0);
4243 if (REGNO (reg
) >= FIRST_PSEUDO_REGISTER
)
4246 n
= HARD_REGNO_NREGS (REGNO (reg
), GET_MODE (reg
));
4254 rtx next
= XEXP (link
, 1);
4255 free_EXPR_LIST_node (link
);
4256 *pprev
= link
= next
;
4262 pprev
= &XEXP (link
, 1);
4269 if (insn
== bb
->end
)
4276 /* Clear LOG_LINKS fields of insns in a selected blocks or whole chain
4277 if blocks is NULL. */
4280 clear_log_links (blocks
)
4288 for (insn
= get_insns (); insn
; insn
= NEXT_INSN (insn
))
4290 free_INSN_LIST_list (&LOG_LINKS (insn
));
4293 EXECUTE_IF_SET_IN_SBITMAP (blocks
, 0, i
,
4295 basic_block bb
= BASIC_BLOCK (i
);
4297 for (insn
= bb
->head
; insn
!= NEXT_INSN (bb
->end
);
4298 insn
= NEXT_INSN (insn
))
4300 free_INSN_LIST_list (&LOG_LINKS (insn
));
4304 /* Given a register bitmap, turn on the bits in a HARD_REG_SET that
4305 correspond to the hard registers, if any, set in that map. This
4306 could be done far more efficiently by having all sorts of special-cases
4307 with moving single words, but probably isn't worth the trouble. */
4310 reg_set_to_hard_reg_set (to
, from
)
4316 EXECUTE_IF_SET_IN_BITMAP
4319 if (i
>= FIRST_PSEUDO_REGISTER
)
4321 SET_HARD_REG_BIT (*to
, i
);