1 /* Data flow analysis for GNU compiler.
2 Copyright (C) 1987, 1988, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
3 1999, 2000, 2001 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 #ifdef HAVE_conditional_execution
172 #ifndef REVERSE_CONDEXEC_PREDICATES_P
173 #define REVERSE_CONDEXEC_PREDICATES_P(x, y) ((x) == reverse_condition (y))
177 /* Nonzero if the second flow pass has completed. */
180 /* Maximum register number used in this function, plus one. */
184 /* Indexed by n, giving various register information */
186 varray_type reg_n_info
;
188 /* Size of a regset for the current function,
189 in (1) bytes and (2) elements. */
194 /* Regset of regs live when calls to `setjmp'-like functions happen. */
195 /* ??? Does this exist only for the setjmp-clobbered warning message? */
197 regset regs_live_at_setjmp
;
199 /* List made of EXPR_LIST rtx's which gives pairs of pseudo registers
200 that have to go in the same hard reg.
201 The first two regs in the list are a pair, and the next two
202 are another pair, etc. */
205 /* Callback that determines if it's ok for a function to have no
206 noreturn attribute. */
207 int (*lang_missing_noreturn_ok_p
) PARAMS ((tree
));
209 /* Set of registers that may be eliminable. These are handled specially
210 in updating regs_ever_live. */
212 static HARD_REG_SET elim_reg_set
;
214 /* Holds information for tracking conditional register life information. */
215 struct reg_cond_life_info
217 /* A boolean expression of conditions under which a register is dead. */
219 /* Conditions under which a register is dead at the basic block end. */
222 /* A boolean expression of conditions under which a register has been
226 /* ??? Could store mask of bytes that are dead, so that we could finally
227 track lifetimes of multi-word registers accessed via subregs. */
230 /* For use in communicating between propagate_block and its subroutines.
231 Holds all information needed to compute life and def-use information. */
233 struct propagate_block_info
235 /* The basic block we're considering. */
238 /* Bit N is set if register N is conditionally or unconditionally live. */
241 /* Bit N is set if register N is set this insn. */
244 /* Element N is the next insn that uses (hard or pseudo) register N
245 within the current basic block; or zero, if there is no such insn. */
248 /* Contains a list of all the MEMs we are tracking for dead store
252 /* If non-null, record the set of registers set unconditionally in the
256 /* If non-null, record the set of registers set conditionally in the
258 regset cond_local_set
;
260 #ifdef HAVE_conditional_execution
261 /* Indexed by register number, holds a reg_cond_life_info for each
262 register that is not unconditionally live or dead. */
263 splay_tree reg_cond_dead
;
265 /* Bit N is set if register N is in an expression in reg_cond_dead. */
269 /* The length of mem_set_list. */
270 int mem_set_list_len
;
272 /* Non-zero if the value of CC0 is live. */
275 /* Flags controling the set of information propagate_block collects. */
279 /* Maximum length of pbi->mem_set_list before we start dropping
280 new elements on the floor. */
281 #define MAX_MEM_SET_LIST_LEN 100
283 /* Forward declarations */
284 static int verify_wide_reg_1
PARAMS ((rtx
*, void *));
285 static void verify_wide_reg
PARAMS ((int, basic_block
));
286 static void verify_local_live_at_start
PARAMS ((regset
, basic_block
));
287 static void notice_stack_pointer_modification_1
PARAMS ((rtx
, rtx
, void *));
288 static void notice_stack_pointer_modification
PARAMS ((rtx
));
289 static void mark_reg
PARAMS ((rtx
, void *));
290 static void mark_regs_live_at_end
PARAMS ((regset
));
291 static int set_phi_alternative_reg
PARAMS ((rtx
, int, int, void *));
292 static void calculate_global_regs_live
PARAMS ((sbitmap
, sbitmap
, int));
293 static void propagate_block_delete_insn
PARAMS ((basic_block
, rtx
));
294 static rtx propagate_block_delete_libcall
PARAMS ((rtx
, rtx
));
295 static int insn_dead_p
PARAMS ((struct propagate_block_info
*,
297 static int libcall_dead_p
PARAMS ((struct propagate_block_info
*,
299 static void mark_set_regs
PARAMS ((struct propagate_block_info
*,
301 static void mark_set_1
PARAMS ((struct propagate_block_info
*,
302 enum rtx_code
, rtx
, rtx
,
304 static int find_regno_partial
PARAMS ((rtx
*, void *));
306 #ifdef HAVE_conditional_execution
307 static int mark_regno_cond_dead
PARAMS ((struct propagate_block_info
*,
309 static void free_reg_cond_life_info
PARAMS ((splay_tree_value
));
310 static int flush_reg_cond_reg_1
PARAMS ((splay_tree_node
, void *));
311 static void flush_reg_cond_reg
PARAMS ((struct propagate_block_info
*,
313 static rtx elim_reg_cond
PARAMS ((rtx
, unsigned int));
314 static rtx ior_reg_cond
PARAMS ((rtx
, rtx
, int));
315 static rtx not_reg_cond
PARAMS ((rtx
));
316 static rtx and_reg_cond
PARAMS ((rtx
, rtx
, int));
319 static void attempt_auto_inc
PARAMS ((struct propagate_block_info
*,
320 rtx
, rtx
, rtx
, rtx
, rtx
));
321 static void find_auto_inc
PARAMS ((struct propagate_block_info
*,
323 static int try_pre_increment_1
PARAMS ((struct propagate_block_info
*,
325 static int try_pre_increment
PARAMS ((rtx
, rtx
, HOST_WIDE_INT
));
327 static void mark_used_reg
PARAMS ((struct propagate_block_info
*,
329 static void mark_used_regs
PARAMS ((struct propagate_block_info
*,
331 void dump_flow_info
PARAMS ((FILE *));
332 void debug_flow_info
PARAMS ((void));
333 static void add_to_mem_set_list
PARAMS ((struct propagate_block_info
*,
335 static void invalidate_mems_from_autoinc
PARAMS ((struct propagate_block_info
*,
337 static void invalidate_mems_from_set
PARAMS ((struct propagate_block_info
*,
339 static void delete_dead_jumptables
PARAMS ((void));
340 static void clear_log_links
PARAMS ((sbitmap
));
344 check_function_return_warnings ()
346 if (warn_missing_noreturn
347 && !TREE_THIS_VOLATILE (cfun
->decl
)
348 && EXIT_BLOCK_PTR
->pred
== NULL
349 && (lang_missing_noreturn_ok_p
350 && !lang_missing_noreturn_ok_p (cfun
->decl
)))
351 warning ("function might be possible candidate for attribute `noreturn'");
353 /* If we have a path to EXIT, then we do return. */
354 if (TREE_THIS_VOLATILE (cfun
->decl
)
355 && EXIT_BLOCK_PTR
->pred
!= NULL
)
356 warning ("`noreturn' function does return");
358 /* If the clobber_return_insn appears in some basic block, then we
359 do reach the end without returning a value. */
360 else if (warn_return_type
361 && cfun
->x_clobber_return_insn
!= NULL
362 && EXIT_BLOCK_PTR
->pred
!= NULL
)
364 int max_uid
= get_max_uid ();
366 /* If clobber_return_insn was excised by jump1, then renumber_insns
367 can make max_uid smaller than the number still recorded in our rtx.
368 That's fine, since this is a quick way of verifying that the insn
369 is no longer in the chain. */
370 if (INSN_UID (cfun
->x_clobber_return_insn
) < max_uid
)
372 /* Recompute insn->block mapping, since the initial mapping is
373 set before we delete unreachable blocks. */
374 if (BLOCK_FOR_INSN (cfun
->x_clobber_return_insn
) != NULL
)
375 warning ("control reaches end of non-void function");
380 /* Return the INSN immediately following the NOTE_INSN_BASIC_BLOCK
381 note associated with the BLOCK. */
384 first_insn_after_basic_block_note (block
)
389 /* Get the first instruction in the block. */
392 if (insn
== NULL_RTX
)
394 if (GET_CODE (insn
) == CODE_LABEL
)
395 insn
= NEXT_INSN (insn
);
396 if (!NOTE_INSN_BASIC_BLOCK_P (insn
))
399 return NEXT_INSN (insn
);
402 /* Perform data flow analysis.
403 F is the first insn of the function; FLAGS is a set of PROP_* flags
404 to be used in accumulating flow info. */
407 life_analysis (f
, file
, flags
)
412 #ifdef ELIMINABLE_REGS
414 static const struct {const int from
, to
; } eliminables
[] = ELIMINABLE_REGS
;
417 /* Record which registers will be eliminated. We use this in
420 CLEAR_HARD_REG_SET (elim_reg_set
);
422 #ifdef ELIMINABLE_REGS
423 for (i
= 0; i
< (int) ARRAY_SIZE (eliminables
); i
++)
424 SET_HARD_REG_BIT (elim_reg_set
, eliminables
[i
].from
);
426 SET_HARD_REG_BIT (elim_reg_set
, FRAME_POINTER_REGNUM
);
430 flags
&= ~(PROP_LOG_LINKS
| PROP_AUTOINC
| PROP_ALLOW_CFG_CHANGES
);
432 /* The post-reload life analysis have (on a global basis) the same
433 registers live as was computed by reload itself. elimination
434 Otherwise offsets and such may be incorrect.
436 Reload will make some registers as live even though they do not
439 We don't want to create new auto-incs after reload, since they
440 are unlikely to be useful and can cause problems with shared
442 if (reload_completed
)
443 flags
&= ~(PROP_REG_INFO
| PROP_AUTOINC
);
445 /* We want alias analysis information for local dead store elimination. */
446 if (optimize
&& (flags
& PROP_SCAN_DEAD_CODE
))
447 init_alias_analysis ();
449 /* Always remove no-op moves. Do this before other processing so
450 that we don't have to keep re-scanning them. */
451 delete_noop_moves (f
);
452 purge_all_dead_edges (false);
454 /* Some targets can emit simpler epilogues if they know that sp was
455 not ever modified during the function. After reload, of course,
456 we've already emitted the epilogue so there's no sense searching. */
457 if (! reload_completed
)
458 notice_stack_pointer_modification (f
);
460 /* Allocate and zero out data structures that will record the
461 data from lifetime analysis. */
462 allocate_reg_life_data ();
463 allocate_bb_life_data ();
465 /* Find the set of registers live on function exit. */
466 mark_regs_live_at_end (EXIT_BLOCK_PTR
->global_live_at_start
);
468 /* "Update" life info from zero. It'd be nice to begin the
469 relaxation with just the exit and noreturn blocks, but that set
470 is not immediately handy. */
472 if (flags
& PROP_REG_INFO
)
473 memset (regs_ever_live
, 0, sizeof (regs_ever_live
));
474 update_life_info (NULL
, UPDATE_LIFE_GLOBAL
, flags
);
477 if (optimize
&& (flags
& PROP_SCAN_DEAD_CODE
))
478 end_alias_analysis ();
481 dump_flow_info (file
);
483 free_basic_block_vars (1);
485 #ifdef ENABLE_CHECKING
489 /* Search for any REG_LABEL notes which reference deleted labels. */
490 for (insn
= get_insns (); insn
; insn
= NEXT_INSN (insn
))
492 rtx inote
= find_reg_note (insn
, REG_LABEL
, NULL_RTX
);
494 if (inote
&& GET_CODE (inote
) == NOTE_INSN_DELETED_LABEL
)
499 /* Removing dead insns should've made jumptables really dead. */
500 delete_dead_jumptables ();
503 /* A subroutine of verify_wide_reg, called through for_each_rtx.
504 Search for REGNO. If found, return 2 if it is not wider than
508 verify_wide_reg_1 (px
, pregno
)
513 unsigned int regno
= *(int *) pregno
;
515 if (GET_CODE (x
) == REG
&& REGNO (x
) == regno
)
517 if (GET_MODE_BITSIZE (GET_MODE (x
)) <= BITS_PER_WORD
)
524 /* A subroutine of verify_local_live_at_start. Search through insns
525 of BB looking for register REGNO. */
528 verify_wide_reg (regno
, bb
)
532 rtx head
= bb
->head
, end
= bb
->end
;
538 int r
= for_each_rtx (&PATTERN (head
), verify_wide_reg_1
, ®no
);
546 head
= NEXT_INSN (head
);
551 fprintf (rtl_dump_file
, "Register %d died unexpectedly.\n", regno
);
552 dump_bb (bb
, rtl_dump_file
);
557 /* A subroutine of update_life_info. Verify that there are no untoward
558 changes in live_at_start during a local update. */
561 verify_local_live_at_start (new_live_at_start
, bb
)
562 regset new_live_at_start
;
565 if (reload_completed
)
567 /* After reload, there are no pseudos, nor subregs of multi-word
568 registers. The regsets should exactly match. */
569 if (! REG_SET_EQUAL_P (new_live_at_start
, bb
->global_live_at_start
))
573 fprintf (rtl_dump_file
,
574 "live_at_start mismatch in bb %d, aborting\nNew:\n",
576 debug_bitmap_file (rtl_dump_file
, new_live_at_start
);
577 fputs ("Old:\n", rtl_dump_file
);
578 dump_bb (bb
, rtl_dump_file
);
587 /* Find the set of changed registers. */
588 XOR_REG_SET (new_live_at_start
, bb
->global_live_at_start
);
590 EXECUTE_IF_SET_IN_REG_SET (new_live_at_start
, 0, i
,
592 /* No registers should die. */
593 if (REGNO_REG_SET_P (bb
->global_live_at_start
, i
))
597 fprintf (rtl_dump_file
,
598 "Register %d died unexpectedly.\n", i
);
599 dump_bb (bb
, rtl_dump_file
);
604 /* Verify that the now-live register is wider than word_mode. */
605 verify_wide_reg (i
, bb
);
610 /* Updates life information starting with the basic blocks set in BLOCKS.
611 If BLOCKS is null, consider it to be the universal set.
613 If EXTENT is UPDATE_LIFE_LOCAL, such as after splitting or peepholeing,
614 we are only expecting local modifications to basic blocks. If we find
615 extra registers live at the beginning of a block, then we either killed
616 useful data, or we have a broken split that wants data not provided.
617 If we find registers removed from live_at_start, that means we have
618 a broken peephole that is killing a register it shouldn't.
620 ??? This is not true in one situation -- when a pre-reload splitter
621 generates subregs of a multi-word pseudo, current life analysis will
622 lose the kill. So we _can_ have a pseudo go live. How irritating.
624 Including PROP_REG_INFO does not properly refresh regs_ever_live
625 unless the caller resets it to zero. */
628 update_life_info (blocks
, extent
, prop_flags
)
630 enum update_life_extent extent
;
634 regset_head tmp_head
;
637 tmp
= INITIALIZE_REG_SET (tmp_head
);
639 timevar_push ((extent
== UPDATE_LIFE_LOCAL
|| blocks
)
640 ? TV_LIFE_UPDATE
: TV_LIFE
);
642 /* Changes to the CFG are only allowed when
643 doing a global update for the entire CFG. */
644 if ((prop_flags
& PROP_ALLOW_CFG_CHANGES
)
645 && (extent
== UPDATE_LIFE_LOCAL
|| blocks
))
648 /* Clear log links in case we are asked to (re)compute them. */
649 if (prop_flags
& PROP_LOG_LINKS
)
650 clear_log_links (blocks
);
652 /* For a global update, we go through the relaxation process again. */
653 if (extent
!= UPDATE_LIFE_LOCAL
)
659 calculate_global_regs_live (blocks
, blocks
,
660 prop_flags
& (PROP_SCAN_DEAD_CODE
661 | PROP_ALLOW_CFG_CHANGES
));
663 if ((prop_flags
& (PROP_KILL_DEAD_CODE
| PROP_ALLOW_CFG_CHANGES
))
664 != (PROP_KILL_DEAD_CODE
| PROP_ALLOW_CFG_CHANGES
))
667 /* Removing dead code may allow the CFG to be simplified which
668 in turn may allow for further dead code detection / removal. */
669 for (i
= n_basic_blocks
- 1; i
>= 0; --i
)
671 basic_block bb
= BASIC_BLOCK (i
);
673 COPY_REG_SET (tmp
, bb
->global_live_at_end
);
674 changed
|= propagate_block (bb
, tmp
, NULL
, NULL
,
675 prop_flags
& (PROP_SCAN_DEAD_CODE
676 | PROP_KILL_DEAD_CODE
));
679 if (! changed
|| ! cleanup_cfg (CLEANUP_EXPENSIVE
))
683 /* If asked, remove notes from the blocks we'll update. */
684 if (extent
== UPDATE_LIFE_GLOBAL_RM_NOTES
)
685 count_or_remove_death_notes (blocks
, 1);
690 EXECUTE_IF_SET_IN_SBITMAP (blocks
, 0, i
,
692 basic_block bb
= BASIC_BLOCK (i
);
694 COPY_REG_SET (tmp
, bb
->global_live_at_end
);
695 propagate_block (bb
, tmp
, NULL
, NULL
, prop_flags
);
697 if (extent
== UPDATE_LIFE_LOCAL
)
698 verify_local_live_at_start (tmp
, bb
);
703 for (i
= n_basic_blocks
- 1; i
>= 0; --i
)
705 basic_block bb
= BASIC_BLOCK (i
);
707 COPY_REG_SET (tmp
, bb
->global_live_at_end
);
708 propagate_block (bb
, tmp
, NULL
, NULL
, prop_flags
);
710 if (extent
== UPDATE_LIFE_LOCAL
)
711 verify_local_live_at_start (tmp
, bb
);
717 if (prop_flags
& PROP_REG_INFO
)
719 /* The only pseudos that are live at the beginning of the function
720 are those that were not set anywhere in the function. local-alloc
721 doesn't know how to handle these correctly, so mark them as not
722 local to any one basic block. */
723 EXECUTE_IF_SET_IN_REG_SET (ENTRY_BLOCK_PTR
->global_live_at_end
,
724 FIRST_PSEUDO_REGISTER
, i
,
725 { REG_BASIC_BLOCK (i
) = REG_BLOCK_GLOBAL
; });
727 /* We have a problem with any pseudoreg that lives across the setjmp.
728 ANSI says that if a user variable does not change in value between
729 the setjmp and the longjmp, then the longjmp preserves it. This
730 includes longjmp from a place where the pseudo appears dead.
731 (In principle, the value still exists if it is in scope.)
732 If the pseudo goes in a hard reg, some other value may occupy
733 that hard reg where this pseudo is dead, thus clobbering the pseudo.
734 Conclusion: such a pseudo must not go in a hard reg. */
735 EXECUTE_IF_SET_IN_REG_SET (regs_live_at_setjmp
,
736 FIRST_PSEUDO_REGISTER
, i
,
738 if (regno_reg_rtx
[i
] != 0)
740 REG_LIVE_LENGTH (i
) = -1;
741 REG_BASIC_BLOCK (i
) = REG_BLOCK_UNKNOWN
;
745 timevar_pop ((extent
== UPDATE_LIFE_LOCAL
|| blocks
)
746 ? TV_LIFE_UPDATE
: TV_LIFE
);
749 /* Free the variables allocated by find_basic_blocks.
751 KEEP_HEAD_END_P is non-zero if basic_block_info is not to be freed. */
754 free_basic_block_vars (keep_head_end_p
)
757 if (! keep_head_end_p
)
759 if (basic_block_info
)
762 VARRAY_FREE (basic_block_info
);
766 ENTRY_BLOCK_PTR
->aux
= NULL
;
767 ENTRY_BLOCK_PTR
->global_live_at_end
= NULL
;
768 EXIT_BLOCK_PTR
->aux
= NULL
;
769 EXIT_BLOCK_PTR
->global_live_at_start
= NULL
;
773 /* Delete any insns that copy a register to itself. */
776 delete_noop_moves (f
)
777 rtx f ATTRIBUTE_UNUSED
;
783 for (i
= 0; i
< n_basic_blocks
; i
++)
785 bb
= BASIC_BLOCK (i
);
786 for (insn
= bb
->head
; insn
!= NEXT_INSN (bb
->end
); insn
= next
)
788 next
= NEXT_INSN (insn
);
789 if (INSN_P (insn
) && noop_move_p (insn
))
793 /* If we're about to remove the first insn of a libcall
794 then move the libcall note to the next real insn and
795 update the retval note. */
796 if ((note
= find_reg_note (insn
, REG_LIBCALL
, NULL_RTX
))
797 && XEXP (note
, 0) != insn
)
799 rtx new_libcall_insn
= next_real_insn (insn
);
800 rtx retval_note
= find_reg_note (XEXP (note
, 0),
801 REG_RETVAL
, NULL_RTX
);
802 REG_NOTES (new_libcall_insn
)
803 = gen_rtx_INSN_LIST (REG_LIBCALL
, XEXP (note
, 0),
804 REG_NOTES (new_libcall_insn
));
805 XEXP (retval_note
, 0) = new_libcall_insn
;
808 /* Do not call delete_insn here since that may change
809 the basic block boundaries which upsets some callers. */
810 PUT_CODE (insn
, NOTE
);
811 NOTE_LINE_NUMBER (insn
) = NOTE_INSN_DELETED
;
812 NOTE_SOURCE_FILE (insn
) = 0;
818 /* Delete any jump tables never referenced. We can't delete them at the
819 time of removing tablejump insn as they are referenced by the preceding
820 insns computing the destination, so we delay deleting and garbagecollect
821 them once life information is computed. */
823 delete_dead_jumptables ()
826 for (insn
= get_insns (); insn
; insn
= next
)
828 next
= NEXT_INSN (insn
);
829 if (GET_CODE (insn
) == CODE_LABEL
830 && LABEL_NUSES (insn
) == LABEL_PRESERVE_P (insn
)
831 && GET_CODE (next
) == JUMP_INSN
832 && (GET_CODE (PATTERN (next
)) == ADDR_VEC
833 || GET_CODE (PATTERN (next
)) == ADDR_DIFF_VEC
))
836 fprintf (rtl_dump_file
, "Dead jumptable %i removed\n", INSN_UID (insn
));
837 delete_insn (NEXT_INSN (insn
));
839 next
= NEXT_INSN (next
);
844 /* Determine if the stack pointer is constant over the life of the function.
845 Only useful before prologues have been emitted. */
848 notice_stack_pointer_modification_1 (x
, pat
, data
)
850 rtx pat ATTRIBUTE_UNUSED
;
851 void *data ATTRIBUTE_UNUSED
;
853 if (x
== stack_pointer_rtx
854 /* The stack pointer is only modified indirectly as the result
855 of a push until later in flow. See the comments in rtl.texi
856 regarding Embedded Side-Effects on Addresses. */
857 || (GET_CODE (x
) == MEM
858 && GET_RTX_CLASS (GET_CODE (XEXP (x
, 0))) == 'a'
859 && XEXP (XEXP (x
, 0), 0) == stack_pointer_rtx
))
860 current_function_sp_is_unchanging
= 0;
864 notice_stack_pointer_modification (f
)
869 /* Assume that the stack pointer is unchanging if alloca hasn't
871 current_function_sp_is_unchanging
= !current_function_calls_alloca
;
872 if (! current_function_sp_is_unchanging
)
875 for (insn
= f
; insn
; insn
= NEXT_INSN (insn
))
879 /* Check if insn modifies the stack pointer. */
880 note_stores (PATTERN (insn
), notice_stack_pointer_modification_1
,
882 if (! current_function_sp_is_unchanging
)
888 /* Mark a register in SET. Hard registers in large modes get all
889 of their component registers set as well. */
896 regset set
= (regset
) xset
;
897 int regno
= REGNO (reg
);
899 if (GET_MODE (reg
) == BLKmode
)
902 SET_REGNO_REG_SET (set
, regno
);
903 if (regno
< FIRST_PSEUDO_REGISTER
)
905 int n
= HARD_REGNO_NREGS (regno
, GET_MODE (reg
));
907 SET_REGNO_REG_SET (set
, regno
+ n
);
911 /* Mark those regs which are needed at the end of the function as live
912 at the end of the last basic block. */
915 mark_regs_live_at_end (set
)
920 /* If exiting needs the right stack value, consider the stack pointer
921 live at the end of the function. */
922 if ((HAVE_epilogue
&& reload_completed
)
923 || ! EXIT_IGNORE_STACK
924 || (! FRAME_POINTER_REQUIRED
925 && ! current_function_calls_alloca
926 && flag_omit_frame_pointer
)
927 || current_function_sp_is_unchanging
)
929 SET_REGNO_REG_SET (set
, STACK_POINTER_REGNUM
);
932 /* Mark the frame pointer if needed at the end of the function. If
933 we end up eliminating it, it will be removed from the live list
934 of each basic block by reload. */
936 if (! reload_completed
|| frame_pointer_needed
)
938 SET_REGNO_REG_SET (set
, FRAME_POINTER_REGNUM
);
939 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
940 /* If they are different, also mark the hard frame pointer as live. */
941 if (! LOCAL_REGNO (HARD_FRAME_POINTER_REGNUM
))
942 SET_REGNO_REG_SET (set
, HARD_FRAME_POINTER_REGNUM
);
946 #ifndef PIC_OFFSET_TABLE_REG_CALL_CLOBBERED
947 /* Many architectures have a GP register even without flag_pic.
948 Assume the pic register is not in use, or will be handled by
949 other means, if it is not fixed. */
950 if (PIC_OFFSET_TABLE_REGNUM
!= INVALID_REGNUM
951 && fixed_regs
[PIC_OFFSET_TABLE_REGNUM
])
952 SET_REGNO_REG_SET (set
, PIC_OFFSET_TABLE_REGNUM
);
955 /* Mark all global registers, and all registers used by the epilogue
956 as being live at the end of the function since they may be
957 referenced by our caller. */
958 for (i
= 0; i
< FIRST_PSEUDO_REGISTER
; i
++)
959 if (global_regs
[i
] || EPILOGUE_USES (i
))
960 SET_REGNO_REG_SET (set
, i
);
962 if (HAVE_epilogue
&& reload_completed
)
964 /* Mark all call-saved registers that we actually used. */
965 for (i
= 0; i
< FIRST_PSEUDO_REGISTER
; i
++)
966 if (regs_ever_live
[i
] && ! LOCAL_REGNO (i
)
967 && ! TEST_HARD_REG_BIT (regs_invalidated_by_call
, i
))
968 SET_REGNO_REG_SET (set
, i
);
971 #ifdef EH_RETURN_DATA_REGNO
972 /* Mark the registers that will contain data for the handler. */
973 if (reload_completed
&& current_function_calls_eh_return
)
976 unsigned regno
= EH_RETURN_DATA_REGNO(i
);
977 if (regno
== INVALID_REGNUM
)
979 SET_REGNO_REG_SET (set
, regno
);
982 #ifdef EH_RETURN_STACKADJ_RTX
983 if ((! HAVE_epilogue
|| ! reload_completed
)
984 && current_function_calls_eh_return
)
986 rtx tmp
= EH_RETURN_STACKADJ_RTX
;
987 if (tmp
&& REG_P (tmp
))
991 #ifdef EH_RETURN_HANDLER_RTX
992 if ((! HAVE_epilogue
|| ! reload_completed
)
993 && current_function_calls_eh_return
)
995 rtx tmp
= EH_RETURN_HANDLER_RTX
;
996 if (tmp
&& REG_P (tmp
))
1001 /* Mark function return value. */
1002 diddle_return_value (mark_reg
, set
);
1005 /* Callback function for for_each_successor_phi. DATA is a regset.
1006 Sets the SRC_REGNO, the regno of the phi alternative for phi node
1007 INSN, in the regset. */
1010 set_phi_alternative_reg (insn
, dest_regno
, src_regno
, data
)
1011 rtx insn ATTRIBUTE_UNUSED
;
1012 int dest_regno ATTRIBUTE_UNUSED
;
1016 regset live
= (regset
) data
;
1017 SET_REGNO_REG_SET (live
, src_regno
);
1021 /* Propagate global life info around the graph of basic blocks. Begin
1022 considering blocks with their corresponding bit set in BLOCKS_IN.
1023 If BLOCKS_IN is null, consider it the universal set.
1025 BLOCKS_OUT is set for every block that was changed. */
1028 calculate_global_regs_live (blocks_in
, blocks_out
, flags
)
1029 sbitmap blocks_in
, blocks_out
;
1032 basic_block
*queue
, *qhead
, *qtail
, *qend
;
1033 regset tmp
, new_live_at_end
, call_used
;
1034 regset_head tmp_head
, call_used_head
;
1035 regset_head new_live_at_end_head
;
1038 tmp
= INITIALIZE_REG_SET (tmp_head
);
1039 new_live_at_end
= INITIALIZE_REG_SET (new_live_at_end_head
);
1040 call_used
= INITIALIZE_REG_SET (call_used_head
);
1042 /* Inconveniently, this is only readily available in hard reg set form. */
1043 for (i
= 0; i
< FIRST_PSEUDO_REGISTER
; ++i
)
1044 if (call_used_regs
[i
])
1045 SET_REGNO_REG_SET (call_used
, i
);
1047 /* Create a worklist. Allocate an extra slot for ENTRY_BLOCK, and one
1048 because the `head == tail' style test for an empty queue doesn't
1049 work with a full queue. */
1050 queue
= (basic_block
*) xmalloc ((n_basic_blocks
+ 2) * sizeof (*queue
));
1052 qhead
= qend
= queue
+ n_basic_blocks
+ 2;
1054 /* Queue the blocks set in the initial mask. Do this in reverse block
1055 number order so that we are more likely for the first round to do
1056 useful work. We use AUX non-null to flag that the block is queued. */
1059 /* Clear out the garbage that might be hanging out in bb->aux. */
1060 for (i
= n_basic_blocks
- 1; i
>= 0; --i
)
1061 BASIC_BLOCK (i
)->aux
= NULL
;
1063 EXECUTE_IF_SET_IN_SBITMAP (blocks_in
, 0, i
,
1065 basic_block bb
= BASIC_BLOCK (i
);
1072 for (i
= 0; i
< n_basic_blocks
; ++i
)
1074 basic_block bb
= BASIC_BLOCK (i
);
1081 sbitmap_zero (blocks_out
);
1083 /* We work through the queue until there are no more blocks. What
1084 is live at the end of this block is precisely the union of what
1085 is live at the beginning of all its successors. So, we set its
1086 GLOBAL_LIVE_AT_END field based on the GLOBAL_LIVE_AT_START field
1087 for its successors. Then, we compute GLOBAL_LIVE_AT_START for
1088 this block by walking through the instructions in this block in
1089 reverse order and updating as we go. If that changed
1090 GLOBAL_LIVE_AT_START, we add the predecessors of the block to the
1091 queue; they will now need to recalculate GLOBAL_LIVE_AT_END.
1093 We are guaranteed to terminate, because GLOBAL_LIVE_AT_START
1094 never shrinks. If a register appears in GLOBAL_LIVE_AT_START, it
1095 must either be live at the end of the block, or used within the
1096 block. In the latter case, it will certainly never disappear
1097 from GLOBAL_LIVE_AT_START. In the former case, the register
1098 could go away only if it disappeared from GLOBAL_LIVE_AT_START
1099 for one of the successor blocks. By induction, that cannot
1101 while (qhead
!= qtail
)
1103 int rescan
, changed
;
1112 /* Begin by propagating live_at_start from the successor blocks. */
1113 CLEAR_REG_SET (new_live_at_end
);
1114 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
1116 basic_block sb
= e
->dest
;
1118 /* Call-clobbered registers die across exception and call edges. */
1119 /* ??? Abnormal call edges ignored for the moment, as this gets
1120 confused by sibling call edges, which crashes reg-stack. */
1121 if (e
->flags
& EDGE_EH
)
1123 bitmap_operation (tmp
, sb
->global_live_at_start
,
1124 call_used
, BITMAP_AND_COMPL
);
1125 IOR_REG_SET (new_live_at_end
, tmp
);
1128 IOR_REG_SET (new_live_at_end
, sb
->global_live_at_start
);
1131 /* The all-important stack pointer must always be live. */
1132 SET_REGNO_REG_SET (new_live_at_end
, STACK_POINTER_REGNUM
);
1134 /* Before reload, there are a few registers that must be forced
1135 live everywhere -- which might not already be the case for
1136 blocks within infinite loops. */
1137 if (! reload_completed
)
1139 /* Any reference to any pseudo before reload is a potential
1140 reference of the frame pointer. */
1141 SET_REGNO_REG_SET (new_live_at_end
, FRAME_POINTER_REGNUM
);
1143 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
1144 /* Pseudos with argument area equivalences may require
1145 reloading via the argument pointer. */
1146 if (fixed_regs
[ARG_POINTER_REGNUM
])
1147 SET_REGNO_REG_SET (new_live_at_end
, ARG_POINTER_REGNUM
);
1150 /* Any constant, or pseudo with constant equivalences, may
1151 require reloading from memory using the pic register. */
1152 if (PIC_OFFSET_TABLE_REGNUM
!= INVALID_REGNUM
1153 && fixed_regs
[PIC_OFFSET_TABLE_REGNUM
])
1154 SET_REGNO_REG_SET (new_live_at_end
, PIC_OFFSET_TABLE_REGNUM
);
1157 /* Regs used in phi nodes are not included in
1158 global_live_at_start, since they are live only along a
1159 particular edge. Set those regs that are live because of a
1160 phi node alternative corresponding to this particular block. */
1162 for_each_successor_phi (bb
, &set_phi_alternative_reg
,
1165 if (bb
== ENTRY_BLOCK_PTR
)
1167 COPY_REG_SET (bb
->global_live_at_end
, new_live_at_end
);
1171 /* On our first pass through this block, we'll go ahead and continue.
1172 Recognize first pass by local_set NULL. On subsequent passes, we
1173 get to skip out early if live_at_end wouldn't have changed. */
1175 if (bb
->local_set
== NULL
)
1177 bb
->local_set
= OBSTACK_ALLOC_REG_SET (&flow_obstack
);
1178 bb
->cond_local_set
= OBSTACK_ALLOC_REG_SET (&flow_obstack
);
1183 /* If any bits were removed from live_at_end, we'll have to
1184 rescan the block. This wouldn't be necessary if we had
1185 precalculated local_live, however with PROP_SCAN_DEAD_CODE
1186 local_live is really dependent on live_at_end. */
1187 CLEAR_REG_SET (tmp
);
1188 rescan
= bitmap_operation (tmp
, bb
->global_live_at_end
,
1189 new_live_at_end
, BITMAP_AND_COMPL
);
1193 /* If any of the registers in the new live_at_end set are
1194 conditionally set in this basic block, we must rescan.
1195 This is because conditional lifetimes at the end of the
1196 block do not just take the live_at_end set into account,
1197 but also the liveness at the start of each successor
1198 block. We can miss changes in those sets if we only
1199 compare the new live_at_end against the previous one. */
1200 CLEAR_REG_SET (tmp
);
1201 rescan
= bitmap_operation (tmp
, new_live_at_end
,
1202 bb
->cond_local_set
, BITMAP_AND
);
1207 /* Find the set of changed bits. Take this opportunity
1208 to notice that this set is empty and early out. */
1209 CLEAR_REG_SET (tmp
);
1210 changed
= bitmap_operation (tmp
, bb
->global_live_at_end
,
1211 new_live_at_end
, BITMAP_XOR
);
1215 /* If any of the changed bits overlap with local_set,
1216 we'll have to rescan the block. Detect overlap by
1217 the AND with ~local_set turning off bits. */
1218 rescan
= bitmap_operation (tmp
, tmp
, bb
->local_set
,
1223 /* Let our caller know that BB changed enough to require its
1224 death notes updated. */
1226 SET_BIT (blocks_out
, bb
->index
);
1230 /* Add to live_at_start the set of all registers in
1231 new_live_at_end that aren't in the old live_at_end. */
1233 bitmap_operation (tmp
, new_live_at_end
, bb
->global_live_at_end
,
1235 COPY_REG_SET (bb
->global_live_at_end
, new_live_at_end
);
1237 changed
= bitmap_operation (bb
->global_live_at_start
,
1238 bb
->global_live_at_start
,
1245 COPY_REG_SET (bb
->global_live_at_end
, new_live_at_end
);
1247 /* Rescan the block insn by insn to turn (a copy of) live_at_end
1248 into live_at_start. */
1249 propagate_block (bb
, new_live_at_end
, bb
->local_set
,
1250 bb
->cond_local_set
, flags
);
1252 /* If live_at start didn't change, no need to go farther. */
1253 if (REG_SET_EQUAL_P (bb
->global_live_at_start
, new_live_at_end
))
1256 COPY_REG_SET (bb
->global_live_at_start
, new_live_at_end
);
1259 /* Queue all predecessors of BB so that we may re-examine
1260 their live_at_end. */
1261 for (e
= bb
->pred
; e
; e
= e
->pred_next
)
1263 basic_block pb
= e
->src
;
1264 if (pb
->aux
== NULL
)
1275 FREE_REG_SET (new_live_at_end
);
1276 FREE_REG_SET (call_used
);
1280 EXECUTE_IF_SET_IN_SBITMAP (blocks_out
, 0, i
,
1282 basic_block bb
= BASIC_BLOCK (i
);
1283 FREE_REG_SET (bb
->local_set
);
1284 FREE_REG_SET (bb
->cond_local_set
);
1289 for (i
= n_basic_blocks
- 1; i
>= 0; --i
)
1291 basic_block bb
= BASIC_BLOCK (i
);
1292 FREE_REG_SET (bb
->local_set
);
1293 FREE_REG_SET (bb
->cond_local_set
);
1301 /* This structure is used to pass parameters to an from the
1302 the function find_regno_partial(). It is used to pass in the
1303 register number we are looking, as well as to return any rtx
1307 unsigned regno_to_find
;
1309 } find_regno_partial_param
;
1312 /* Find the rtx for the reg numbers specified in 'data' if it is
1313 part of an expression which only uses part of the register. Return
1314 it in the structure passed in. */
1316 find_regno_partial (ptr
, data
)
1320 find_regno_partial_param
*param
= (find_regno_partial_param
*)data
;
1321 unsigned reg
= param
->regno_to_find
;
1322 param
->retval
= NULL_RTX
;
1324 if (*ptr
== NULL_RTX
)
1327 switch (GET_CODE (*ptr
))
1331 case STRICT_LOW_PART
:
1332 if (GET_CODE (XEXP (*ptr
, 0)) == REG
&& REGNO (XEXP (*ptr
, 0)) == reg
)
1334 param
->retval
= XEXP (*ptr
, 0);
1340 if (GET_CODE (SUBREG_REG (*ptr
)) == REG
1341 && REGNO (SUBREG_REG (*ptr
)) == reg
)
1343 param
->retval
= SUBREG_REG (*ptr
);
1355 /* Process all immediate successors of the entry block looking for pseudo
1356 registers which are live on entry. Find all of those whose first
1357 instance is a partial register reference of some kind, and initialize
1358 them to 0 after the entry block. This will prevent bit sets within
1359 registers whose value is unknown, and may contain some kind of sticky
1360 bits we don't want. */
1363 initialize_uninitialized_subregs ()
1367 int reg
, did_something
= 0;
1368 find_regno_partial_param param
;
1370 for (e
= ENTRY_BLOCK_PTR
->succ
; e
; e
= e
->succ_next
)
1372 basic_block bb
= e
->dest
;
1373 regset map
= bb
->global_live_at_start
;
1374 EXECUTE_IF_SET_IN_REG_SET (map
,
1375 FIRST_PSEUDO_REGISTER
, reg
,
1377 int uid
= REGNO_FIRST_UID (reg
);
1380 /* Find an insn which mentions the register we are looking for.
1381 Its preferable to have an instance of the register's rtl since
1382 there may be various flags set which we need to duplicate.
1383 If we can't find it, its probably an automatic whose initial
1384 value doesn't matter, or hopefully something we don't care about. */
1385 for (i
= get_insns (); i
&& INSN_UID (i
) != uid
; i
= NEXT_INSN (i
))
1389 /* Found the insn, now get the REG rtx, if we can. */
1390 param
.regno_to_find
= reg
;
1391 for_each_rtx (&i
, find_regno_partial
, ¶m
);
1392 if (param
.retval
!= NULL_RTX
)
1394 insn
= gen_move_insn (param
.retval
,
1395 CONST0_RTX (GET_MODE (param
.retval
)));
1396 insert_insn_on_edge (insn
, e
);
1404 commit_edge_insertions ();
1405 return did_something
;
1409 /* Subroutines of life analysis. */
1411 /* Allocate the permanent data structures that represent the results
1412 of life analysis. Not static since used also for stupid life analysis. */
1415 allocate_bb_life_data ()
1419 for (i
= 0; i
< n_basic_blocks
; i
++)
1421 basic_block bb
= BASIC_BLOCK (i
);
1423 bb
->global_live_at_start
= OBSTACK_ALLOC_REG_SET (&flow_obstack
);
1424 bb
->global_live_at_end
= OBSTACK_ALLOC_REG_SET (&flow_obstack
);
1427 ENTRY_BLOCK_PTR
->global_live_at_end
1428 = OBSTACK_ALLOC_REG_SET (&flow_obstack
);
1429 EXIT_BLOCK_PTR
->global_live_at_start
1430 = OBSTACK_ALLOC_REG_SET (&flow_obstack
);
1432 regs_live_at_setjmp
= OBSTACK_ALLOC_REG_SET (&flow_obstack
);
1436 allocate_reg_life_data ()
1440 max_regno
= max_reg_num ();
1442 /* Recalculate the register space, in case it has grown. Old style
1443 vector oriented regsets would set regset_{size,bytes} here also. */
1444 allocate_reg_info (max_regno
, FALSE
, FALSE
);
1446 /* Reset all the data we'll collect in propagate_block and its
1448 for (i
= 0; i
< max_regno
; i
++)
1452 REG_N_DEATHS (i
) = 0;
1453 REG_N_CALLS_CROSSED (i
) = 0;
1454 REG_LIVE_LENGTH (i
) = 0;
1455 REG_BASIC_BLOCK (i
) = REG_BLOCK_UNKNOWN
;
1459 /* Delete dead instructions for propagate_block. */
1462 propagate_block_delete_insn (bb
, insn
)
1466 rtx inote
= find_reg_note (insn
, REG_LABEL
, NULL_RTX
);
1469 /* If the insn referred to a label, and that label was attached to
1470 an ADDR_VEC, it's safe to delete the ADDR_VEC. In fact, it's
1471 pretty much mandatory to delete it, because the ADDR_VEC may be
1472 referencing labels that no longer exist.
1474 INSN may reference a deleted label, particularly when a jump
1475 table has been optimized into a direct jump. There's no
1476 real good way to fix up the reference to the deleted label
1477 when the label is deleted, so we just allow it here.
1479 After dead code elimination is complete, we do search for
1480 any REG_LABEL notes which reference deleted labels as a
1483 if (inote
&& GET_CODE (inote
) == CODE_LABEL
)
1485 rtx label
= XEXP (inote
, 0);
1488 /* The label may be forced if it has been put in the constant
1489 pool. If that is the only use we must discard the table
1490 jump following it, but not the label itself. */
1491 if (LABEL_NUSES (label
) == 1 + LABEL_PRESERVE_P (label
)
1492 && (next
= next_nonnote_insn (label
)) != NULL
1493 && GET_CODE (next
) == JUMP_INSN
1494 && (GET_CODE (PATTERN (next
)) == ADDR_VEC
1495 || GET_CODE (PATTERN (next
)) == ADDR_DIFF_VEC
))
1497 rtx pat
= PATTERN (next
);
1498 int diff_vec_p
= GET_CODE (pat
) == ADDR_DIFF_VEC
;
1499 int len
= XVECLEN (pat
, diff_vec_p
);
1502 for (i
= 0; i
< len
; i
++)
1503 LABEL_NUSES (XEXP (XVECEXP (pat
, diff_vec_p
, i
), 0))--;
1509 if (bb
->end
== insn
)
1513 purge_dead_edges (bb
);
1516 /* Delete dead libcalls for propagate_block. Return the insn
1517 before the libcall. */
1520 propagate_block_delete_libcall ( insn
, note
)
1523 rtx first
= XEXP (note
, 0);
1524 rtx before
= PREV_INSN (first
);
1526 delete_insn_chain (first
, insn
);
1530 /* Update the life-status of regs for one insn. Return the previous insn. */
1533 propagate_one_insn (pbi
, insn
)
1534 struct propagate_block_info
*pbi
;
1537 rtx prev
= PREV_INSN (insn
);
1538 int flags
= pbi
->flags
;
1539 int insn_is_dead
= 0;
1540 int libcall_is_dead
= 0;
1544 if (! INSN_P (insn
))
1547 note
= find_reg_note (insn
, REG_RETVAL
, NULL_RTX
);
1548 if (flags
& PROP_SCAN_DEAD_CODE
)
1550 insn_is_dead
= insn_dead_p (pbi
, PATTERN (insn
), 0, REG_NOTES (insn
));
1551 libcall_is_dead
= (insn_is_dead
&& note
!= 0
1552 && libcall_dead_p (pbi
, note
, insn
));
1555 /* If an instruction consists of just dead store(s) on final pass,
1557 if ((flags
& PROP_KILL_DEAD_CODE
) && insn_is_dead
)
1559 /* If we're trying to delete a prologue or epilogue instruction
1560 that isn't flagged as possibly being dead, something is wrong.
1561 But if we are keeping the stack pointer depressed, we might well
1562 be deleting insns that are used to compute the amount to update
1563 it by, so they are fine. */
1564 if (reload_completed
1565 && !(TREE_CODE (TREE_TYPE (current_function_decl
)) == FUNCTION_TYPE
1566 && (TYPE_RETURNS_STACK_DEPRESSED
1567 (TREE_TYPE (current_function_decl
))))
1568 && (((HAVE_epilogue
|| HAVE_prologue
)
1569 && prologue_epilogue_contains (insn
))
1570 || (HAVE_sibcall_epilogue
1571 && sibcall_epilogue_contains (insn
)))
1572 && find_reg_note (insn
, REG_MAYBE_DEAD
, NULL_RTX
) == 0)
1573 fatal_insn ("Attempt to delete prologue/epilogue insn:", insn
);
1575 /* Record sets. Do this even for dead instructions, since they
1576 would have killed the values if they hadn't been deleted. */
1577 mark_set_regs (pbi
, PATTERN (insn
), insn
);
1579 /* CC0 is now known to be dead. Either this insn used it,
1580 in which case it doesn't anymore, or clobbered it,
1581 so the next insn can't use it. */
1584 if (libcall_is_dead
)
1585 prev
= propagate_block_delete_libcall ( insn
, note
);
1587 propagate_block_delete_insn (pbi
->bb
, insn
);
1592 /* See if this is an increment or decrement that can be merged into
1593 a following memory address. */
1596 rtx x
= single_set (insn
);
1598 /* Does this instruction increment or decrement a register? */
1599 if ((flags
& PROP_AUTOINC
)
1601 && GET_CODE (SET_DEST (x
)) == REG
1602 && (GET_CODE (SET_SRC (x
)) == PLUS
1603 || GET_CODE (SET_SRC (x
)) == MINUS
)
1604 && XEXP (SET_SRC (x
), 0) == SET_DEST (x
)
1605 && GET_CODE (XEXP (SET_SRC (x
), 1)) == CONST_INT
1606 /* Ok, look for a following memory ref we can combine with.
1607 If one is found, change the memory ref to a PRE_INC
1608 or PRE_DEC, cancel this insn, and return 1.
1609 Return 0 if nothing has been done. */
1610 && try_pre_increment_1 (pbi
, insn
))
1613 #endif /* AUTO_INC_DEC */
1615 CLEAR_REG_SET (pbi
->new_set
);
1617 /* If this is not the final pass, and this insn is copying the value of
1618 a library call and it's dead, don't scan the insns that perform the
1619 library call, so that the call's arguments are not marked live. */
1620 if (libcall_is_dead
)
1622 /* Record the death of the dest reg. */
1623 mark_set_regs (pbi
, PATTERN (insn
), insn
);
1625 insn
= XEXP (note
, 0);
1626 return PREV_INSN (insn
);
1628 else if (GET_CODE (PATTERN (insn
)) == SET
1629 && SET_DEST (PATTERN (insn
)) == stack_pointer_rtx
1630 && GET_CODE (SET_SRC (PATTERN (insn
))) == PLUS
1631 && XEXP (SET_SRC (PATTERN (insn
)), 0) == stack_pointer_rtx
1632 && GET_CODE (XEXP (SET_SRC (PATTERN (insn
)), 1)) == CONST_INT
)
1633 /* We have an insn to pop a constant amount off the stack.
1634 (Such insns use PLUS regardless of the direction of the stack,
1635 and any insn to adjust the stack by a constant is always a pop.)
1636 These insns, if not dead stores, have no effect on life. */
1641 /* Any regs live at the time of a call instruction must not go
1642 in a register clobbered by calls. Find all regs now live and
1643 record this for them. */
1645 if (GET_CODE (insn
) == CALL_INSN
&& (flags
& PROP_REG_INFO
))
1646 EXECUTE_IF_SET_IN_REG_SET (pbi
->reg_live
, 0, i
,
1647 { REG_N_CALLS_CROSSED (i
)++; });
1649 /* Record sets. Do this even for dead instructions, since they
1650 would have killed the values if they hadn't been deleted. */
1651 mark_set_regs (pbi
, PATTERN (insn
), insn
);
1653 if (GET_CODE (insn
) == CALL_INSN
)
1659 if (GET_CODE (PATTERN (insn
)) == COND_EXEC
)
1660 cond
= COND_EXEC_TEST (PATTERN (insn
));
1662 /* Non-constant calls clobber memory. */
1663 if (! CONST_OR_PURE_CALL_P (insn
))
1665 free_EXPR_LIST_list (&pbi
->mem_set_list
);
1666 pbi
->mem_set_list_len
= 0;
1669 /* There may be extra registers to be clobbered. */
1670 for (note
= CALL_INSN_FUNCTION_USAGE (insn
);
1672 note
= XEXP (note
, 1))
1673 if (GET_CODE (XEXP (note
, 0)) == CLOBBER
)
1674 mark_set_1 (pbi
, CLOBBER
, XEXP (XEXP (note
, 0), 0),
1675 cond
, insn
, pbi
->flags
);
1677 /* Calls change all call-used and global registers. */
1678 for (i
= 0; i
< FIRST_PSEUDO_REGISTER
; i
++)
1679 if (TEST_HARD_REG_BIT (regs_invalidated_by_call
, i
))
1681 /* We do not want REG_UNUSED notes for these registers. */
1682 mark_set_1 (pbi
, CLOBBER
, gen_rtx_REG (reg_raw_mode
[i
], i
),
1684 pbi
->flags
& ~(PROP_DEATH_NOTES
| PROP_REG_INFO
));
1688 /* If an insn doesn't use CC0, it becomes dead since we assume
1689 that every insn clobbers it. So show it dead here;
1690 mark_used_regs will set it live if it is referenced. */
1695 mark_used_regs (pbi
, PATTERN (insn
), NULL_RTX
, insn
);
1696 if ((flags
& PROP_EQUAL_NOTES
)
1697 && ((note
= find_reg_note (insn
, REG_EQUAL
, NULL_RTX
))
1698 || (note
= find_reg_note (insn
, REG_EQUIV
, NULL_RTX
))))
1699 mark_used_regs (pbi
, XEXP (note
, 0), NULL_RTX
, insn
);
1701 /* Sometimes we may have inserted something before INSN (such as a move)
1702 when we make an auto-inc. So ensure we will scan those insns. */
1704 prev
= PREV_INSN (insn
);
1707 if (! insn_is_dead
&& GET_CODE (insn
) == CALL_INSN
)
1713 if (GET_CODE (PATTERN (insn
)) == COND_EXEC
)
1714 cond
= COND_EXEC_TEST (PATTERN (insn
));
1716 /* Calls use their arguments. */
1717 for (note
= CALL_INSN_FUNCTION_USAGE (insn
);
1719 note
= XEXP (note
, 1))
1720 if (GET_CODE (XEXP (note
, 0)) == USE
)
1721 mark_used_regs (pbi
, XEXP (XEXP (note
, 0), 0),
1724 /* The stack ptr is used (honorarily) by a CALL insn. */
1725 SET_REGNO_REG_SET (pbi
->reg_live
, STACK_POINTER_REGNUM
);
1727 /* Calls may also reference any of the global registers,
1728 so they are made live. */
1729 for (i
= 0; i
< FIRST_PSEUDO_REGISTER
; i
++)
1731 mark_used_reg (pbi
, gen_rtx_REG (reg_raw_mode
[i
], i
),
1736 /* On final pass, update counts of how many insns in which each reg
1738 if (flags
& PROP_REG_INFO
)
1739 EXECUTE_IF_SET_IN_REG_SET (pbi
->reg_live
, 0, i
,
1740 { REG_LIVE_LENGTH (i
)++; });
1745 /* Initialize a propagate_block_info struct for public consumption.
1746 Note that the structure itself is opaque to this file, but that
1747 the user can use the regsets provided here. */
1749 struct propagate_block_info
*
1750 init_propagate_block_info (bb
, live
, local_set
, cond_local_set
, flags
)
1752 regset live
, local_set
, cond_local_set
;
1755 struct propagate_block_info
*pbi
= xmalloc (sizeof (*pbi
));
1758 pbi
->reg_live
= live
;
1759 pbi
->mem_set_list
= NULL_RTX
;
1760 pbi
->mem_set_list_len
= 0;
1761 pbi
->local_set
= local_set
;
1762 pbi
->cond_local_set
= cond_local_set
;
1766 if (flags
& (PROP_LOG_LINKS
| PROP_AUTOINC
))
1767 pbi
->reg_next_use
= (rtx
*) xcalloc (max_reg_num (), sizeof (rtx
));
1769 pbi
->reg_next_use
= NULL
;
1771 pbi
->new_set
= BITMAP_XMALLOC ();
1773 #ifdef HAVE_conditional_execution
1774 pbi
->reg_cond_dead
= splay_tree_new (splay_tree_compare_ints
, NULL
,
1775 free_reg_cond_life_info
);
1776 pbi
->reg_cond_reg
= BITMAP_XMALLOC ();
1778 /* If this block ends in a conditional branch, for each register live
1779 from one side of the branch and not the other, record the register
1780 as conditionally dead. */
1781 if (GET_CODE (bb
->end
) == JUMP_INSN
1782 && any_condjump_p (bb
->end
))
1784 regset_head diff_head
;
1785 regset diff
= INITIALIZE_REG_SET (diff_head
);
1786 basic_block bb_true
, bb_false
;
1787 rtx cond_true
, cond_false
, set_src
;
1790 /* Identify the successor blocks. */
1791 bb_true
= bb
->succ
->dest
;
1792 if (bb
->succ
->succ_next
!= NULL
)
1794 bb_false
= bb
->succ
->succ_next
->dest
;
1796 if (bb
->succ
->flags
& EDGE_FALLTHRU
)
1798 basic_block t
= bb_false
;
1802 else if (! (bb
->succ
->succ_next
->flags
& EDGE_FALLTHRU
))
1807 /* This can happen with a conditional jump to the next insn. */
1808 if (JUMP_LABEL (bb
->end
) != bb_true
->head
)
1811 /* Simplest way to do nothing. */
1815 /* Extract the condition from the branch. */
1816 set_src
= SET_SRC (pc_set (bb
->end
));
1817 cond_true
= XEXP (set_src
, 0);
1818 cond_false
= gen_rtx_fmt_ee (reverse_condition (GET_CODE (cond_true
)),
1819 GET_MODE (cond_true
), XEXP (cond_true
, 0),
1820 XEXP (cond_true
, 1));
1821 if (GET_CODE (XEXP (set_src
, 1)) == PC
)
1824 cond_false
= cond_true
;
1828 /* Compute which register lead different lives in the successors. */
1829 if (bitmap_operation (diff
, bb_true
->global_live_at_start
,
1830 bb_false
->global_live_at_start
, BITMAP_XOR
))
1832 rtx reg
= XEXP (cond_true
, 0);
1834 if (GET_CODE (reg
) == SUBREG
)
1835 reg
= SUBREG_REG (reg
);
1837 if (GET_CODE (reg
) != REG
)
1840 SET_REGNO_REG_SET (pbi
->reg_cond_reg
, REGNO (reg
));
1842 /* For each such register, mark it conditionally dead. */
1843 EXECUTE_IF_SET_IN_REG_SET
1846 struct reg_cond_life_info
*rcli
;
1849 rcli
= (struct reg_cond_life_info
*) xmalloc (sizeof (*rcli
));
1851 if (REGNO_REG_SET_P (bb_true
->global_live_at_start
, i
))
1855 rcli
->condition
= cond
;
1856 rcli
->stores
= const0_rtx
;
1857 rcli
->orig_condition
= cond
;
1859 splay_tree_insert (pbi
->reg_cond_dead
, i
,
1860 (splay_tree_value
) rcli
);
1864 FREE_REG_SET (diff
);
1868 /* If this block has no successors, any stores to the frame that aren't
1869 used later in the block are dead. So make a pass over the block
1870 recording any such that are made and show them dead at the end. We do
1871 a very conservative and simple job here. */
1873 && ! (TREE_CODE (TREE_TYPE (current_function_decl
)) == FUNCTION_TYPE
1874 && (TYPE_RETURNS_STACK_DEPRESSED
1875 (TREE_TYPE (current_function_decl
))))
1876 && (flags
& PROP_SCAN_DEAD_CODE
)
1877 && (bb
->succ
== NULL
1878 || (bb
->succ
->succ_next
== NULL
1879 && bb
->succ
->dest
== EXIT_BLOCK_PTR
1880 && ! current_function_calls_eh_return
)))
1883 for (insn
= bb
->end
; insn
!= bb
->head
; insn
= PREV_INSN (insn
))
1884 if (GET_CODE (insn
) == INSN
1885 && (set
= single_set (insn
))
1886 && GET_CODE (SET_DEST (set
)) == MEM
)
1888 rtx mem
= SET_DEST (set
);
1889 rtx canon_mem
= canon_rtx (mem
);
1891 /* This optimization is performed by faking a store to the
1892 memory at the end of the block. This doesn't work for
1893 unchanging memories because multiple stores to unchanging
1894 memory is illegal and alias analysis doesn't consider it. */
1895 if (RTX_UNCHANGING_P (canon_mem
))
1898 if (XEXP (canon_mem
, 0) == frame_pointer_rtx
1899 || (GET_CODE (XEXP (canon_mem
, 0)) == PLUS
1900 && XEXP (XEXP (canon_mem
, 0), 0) == frame_pointer_rtx
1901 && GET_CODE (XEXP (XEXP (canon_mem
, 0), 1)) == CONST_INT
))
1902 add_to_mem_set_list (pbi
, canon_mem
);
1909 /* Release a propagate_block_info struct. */
1912 free_propagate_block_info (pbi
)
1913 struct propagate_block_info
*pbi
;
1915 free_EXPR_LIST_list (&pbi
->mem_set_list
);
1917 BITMAP_XFREE (pbi
->new_set
);
1919 #ifdef HAVE_conditional_execution
1920 splay_tree_delete (pbi
->reg_cond_dead
);
1921 BITMAP_XFREE (pbi
->reg_cond_reg
);
1924 if (pbi
->reg_next_use
)
1925 free (pbi
->reg_next_use
);
1930 /* Compute the registers live at the beginning of a basic block BB from
1931 those live at the end.
1933 When called, REG_LIVE contains those live at the end. On return, it
1934 contains those live at the beginning.
1936 LOCAL_SET, if non-null, will be set with all registers killed
1937 unconditionally by this basic block.
1938 Likewise, COND_LOCAL_SET, if non-null, will be set with all registers
1939 killed conditionally by this basic block. If there is any unconditional
1940 set of a register, then the corresponding bit will be set in LOCAL_SET
1941 and cleared in COND_LOCAL_SET.
1942 It is valid for LOCAL_SET and COND_LOCAL_SET to be the same set. In this
1943 case, the resulting set will be equal to the union of the two sets that
1944 would otherwise be computed.
1946 Return non-zero if an INSN is deleted (i.e. by dead code removal). */
1949 propagate_block (bb
, live
, local_set
, cond_local_set
, flags
)
1953 regset cond_local_set
;
1956 struct propagate_block_info
*pbi
;
1960 pbi
= init_propagate_block_info (bb
, live
, local_set
, cond_local_set
, flags
);
1962 if (flags
& PROP_REG_INFO
)
1966 /* Process the regs live at the end of the block.
1967 Mark them as not local to any one basic block. */
1968 EXECUTE_IF_SET_IN_REG_SET (live
, 0, i
,
1969 { REG_BASIC_BLOCK (i
) = REG_BLOCK_GLOBAL
; });
1972 /* Scan the block an insn at a time from end to beginning. */
1975 for (insn
= bb
->end
;; insn
= prev
)
1977 /* If this is a call to `setjmp' et al, warn if any
1978 non-volatile datum is live. */
1979 if ((flags
& PROP_REG_INFO
)
1980 && GET_CODE (insn
) == CALL_INSN
1981 && find_reg_note (insn
, REG_SETJMP
, NULL
))
1982 IOR_REG_SET (regs_live_at_setjmp
, pbi
->reg_live
);
1984 prev
= propagate_one_insn (pbi
, insn
);
1985 changed
|= NEXT_INSN (prev
) != insn
;
1987 if (insn
== bb
->head
)
1991 free_propagate_block_info (pbi
);
1996 /* Return 1 if X (the body of an insn, or part of it) is just dead stores
1997 (SET expressions whose destinations are registers dead after the insn).
1998 NEEDED is the regset that says which regs are alive after the insn.
2000 Unless CALL_OK is non-zero, an insn is needed if it contains a CALL.
2002 If X is the entire body of an insn, NOTES contains the reg notes
2003 pertaining to the insn. */
2006 insn_dead_p (pbi
, x
, call_ok
, notes
)
2007 struct propagate_block_info
*pbi
;
2010 rtx notes ATTRIBUTE_UNUSED
;
2012 enum rtx_code code
= GET_CODE (x
);
2015 /* As flow is invoked after combine, we must take existing AUTO_INC
2016 expressions into account. */
2017 for (; notes
; notes
= XEXP (notes
, 1))
2019 if (REG_NOTE_KIND (notes
) == REG_INC
)
2021 int regno
= REGNO (XEXP (notes
, 0));
2023 /* Don't delete insns to set global regs. */
2024 if ((regno
< FIRST_PSEUDO_REGISTER
&& global_regs
[regno
])
2025 || REGNO_REG_SET_P (pbi
->reg_live
, regno
))
2031 /* If setting something that's a reg or part of one,
2032 see if that register's altered value will be live. */
2036 rtx r
= SET_DEST (x
);
2039 if (GET_CODE (r
) == CC0
)
2040 return ! pbi
->cc0_live
;
2043 /* A SET that is a subroutine call cannot be dead. */
2044 if (GET_CODE (SET_SRC (x
)) == CALL
)
2050 /* Don't eliminate loads from volatile memory or volatile asms. */
2051 else if (volatile_refs_p (SET_SRC (x
)))
2054 if (GET_CODE (r
) == MEM
)
2058 if (MEM_VOLATILE_P (r
) || GET_MODE (r
) == BLKmode
)
2061 canon_r
= canon_rtx (r
);
2063 /* Walk the set of memory locations we are currently tracking
2064 and see if one is an identical match to this memory location.
2065 If so, this memory write is dead (remember, we're walking
2066 backwards from the end of the block to the start). Since
2067 rtx_equal_p does not check the alias set or flags, we also
2068 must have the potential for them to conflict (anti_dependence). */
2069 for (temp
= pbi
->mem_set_list
; temp
!= 0; temp
= XEXP (temp
, 1))
2070 if (anti_dependence (r
, XEXP (temp
, 0)))
2072 rtx mem
= XEXP (temp
, 0);
2074 if (rtx_equal_p (XEXP (canon_r
, 0), XEXP (mem
, 0))
2075 && (GET_MODE_SIZE (GET_MODE (canon_r
))
2076 <= GET_MODE_SIZE (GET_MODE (mem
))))
2080 /* Check if memory reference matches an auto increment. Only
2081 post increment/decrement or modify are valid. */
2082 if (GET_MODE (mem
) == GET_MODE (r
)
2083 && (GET_CODE (XEXP (mem
, 0)) == POST_DEC
2084 || GET_CODE (XEXP (mem
, 0)) == POST_INC
2085 || GET_CODE (XEXP (mem
, 0)) == POST_MODIFY
)
2086 && GET_MODE (XEXP (mem
, 0)) == GET_MODE (r
)
2087 && rtx_equal_p (XEXP (XEXP (mem
, 0), 0), XEXP (r
, 0)))
2094 while (GET_CODE (r
) == SUBREG
2095 || GET_CODE (r
) == STRICT_LOW_PART
2096 || GET_CODE (r
) == ZERO_EXTRACT
)
2099 if (GET_CODE (r
) == REG
)
2101 int regno
= REGNO (r
);
2104 if (REGNO_REG_SET_P (pbi
->reg_live
, regno
))
2107 /* If this is a hard register, verify that subsequent
2108 words are not needed. */
2109 if (regno
< FIRST_PSEUDO_REGISTER
)
2111 int n
= HARD_REGNO_NREGS (regno
, GET_MODE (r
));
2114 if (REGNO_REG_SET_P (pbi
->reg_live
, regno
+n
))
2118 /* Don't delete insns to set global regs. */
2119 if (regno
< FIRST_PSEUDO_REGISTER
&& global_regs
[regno
])
2122 /* Make sure insns to set the stack pointer aren't deleted. */
2123 if (regno
== STACK_POINTER_REGNUM
)
2126 /* ??? These bits might be redundant with the force live bits
2127 in calculate_global_regs_live. We would delete from
2128 sequential sets; whether this actually affects real code
2129 for anything but the stack pointer I don't know. */
2130 /* Make sure insns to set the frame pointer aren't deleted. */
2131 if (regno
== FRAME_POINTER_REGNUM
2132 && (! reload_completed
|| frame_pointer_needed
))
2134 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
2135 if (regno
== HARD_FRAME_POINTER_REGNUM
2136 && (! reload_completed
|| frame_pointer_needed
))
2140 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
2141 /* Make sure insns to set arg pointer are never deleted
2142 (if the arg pointer isn't fixed, there will be a USE
2143 for it, so we can treat it normally). */
2144 if (regno
== ARG_POINTER_REGNUM
&& fixed_regs
[regno
])
2148 /* Otherwise, the set is dead. */
2154 /* If performing several activities, insn is dead if each activity
2155 is individually dead. Also, CLOBBERs and USEs can be ignored; a
2156 CLOBBER or USE that's inside a PARALLEL doesn't make the insn
2158 else if (code
== PARALLEL
)
2160 int i
= XVECLEN (x
, 0);
2162 for (i
--; i
>= 0; i
--)
2163 if (GET_CODE (XVECEXP (x
, 0, i
)) != CLOBBER
2164 && GET_CODE (XVECEXP (x
, 0, i
)) != USE
2165 && ! insn_dead_p (pbi
, XVECEXP (x
, 0, i
), call_ok
, NULL_RTX
))
2171 /* A CLOBBER of a pseudo-register that is dead serves no purpose. That
2172 is not necessarily true for hard registers. */
2173 else if (code
== CLOBBER
&& GET_CODE (XEXP (x
, 0)) == REG
2174 && REGNO (XEXP (x
, 0)) >= FIRST_PSEUDO_REGISTER
2175 && ! REGNO_REG_SET_P (pbi
->reg_live
, REGNO (XEXP (x
, 0))))
2178 /* We do not check other CLOBBER or USE here. An insn consisting of just
2179 a CLOBBER or just a USE should not be deleted. */
2183 /* If INSN is the last insn in a libcall, and assuming INSN is dead,
2184 return 1 if the entire library call is dead.
2185 This is true if INSN copies a register (hard or pseudo)
2186 and if the hard return reg of the call insn is dead.
2187 (The caller should have tested the destination of the SET inside
2188 INSN already for death.)
2190 If this insn doesn't just copy a register, then we don't
2191 have an ordinary libcall. In that case, cse could not have
2192 managed to substitute the source for the dest later on,
2193 so we can assume the libcall is dead.
2195 PBI is the block info giving pseudoregs live before this insn.
2196 NOTE is the REG_RETVAL note of the insn. */
2199 libcall_dead_p (pbi
, note
, insn
)
2200 struct propagate_block_info
*pbi
;
2204 rtx x
= single_set (insn
);
2208 rtx r
= SET_SRC (x
);
2210 if (GET_CODE (r
) == REG
)
2212 rtx call
= XEXP (note
, 0);
2216 /* Find the call insn. */
2217 while (call
!= insn
&& GET_CODE (call
) != CALL_INSN
)
2218 call
= NEXT_INSN (call
);
2220 /* If there is none, do nothing special,
2221 since ordinary death handling can understand these insns. */
2225 /* See if the hard reg holding the value is dead.
2226 If this is a PARALLEL, find the call within it. */
2227 call_pat
= PATTERN (call
);
2228 if (GET_CODE (call_pat
) == PARALLEL
)
2230 for (i
= XVECLEN (call_pat
, 0) - 1; i
>= 0; i
--)
2231 if (GET_CODE (XVECEXP (call_pat
, 0, i
)) == SET
2232 && GET_CODE (SET_SRC (XVECEXP (call_pat
, 0, i
))) == CALL
)
2235 /* This may be a library call that is returning a value
2236 via invisible pointer. Do nothing special, since
2237 ordinary death handling can understand these insns. */
2241 call_pat
= XVECEXP (call_pat
, 0, i
);
2244 return insn_dead_p (pbi
, call_pat
, 1, REG_NOTES (call
));
2250 /* Return 1 if register REGNO was used before it was set, i.e. if it is
2251 live at function entry. Don't count global register variables, variables
2252 in registers that can be used for function arg passing, or variables in
2253 fixed hard registers. */
2256 regno_uninitialized (regno
)
2259 if (n_basic_blocks
== 0
2260 || (regno
< FIRST_PSEUDO_REGISTER
2261 && (global_regs
[regno
]
2262 || fixed_regs
[regno
]
2263 || FUNCTION_ARG_REGNO_P (regno
))))
2266 return REGNO_REG_SET_P (BASIC_BLOCK (0)->global_live_at_start
, regno
);
2269 /* 1 if register REGNO was alive at a place where `setjmp' was called
2270 and was set more than once or is an argument.
2271 Such regs may be clobbered by `longjmp'. */
2274 regno_clobbered_at_setjmp (regno
)
2277 if (n_basic_blocks
== 0)
2280 return ((REG_N_SETS (regno
) > 1
2281 || REGNO_REG_SET_P (BASIC_BLOCK (0)->global_live_at_start
, regno
))
2282 && REGNO_REG_SET_P (regs_live_at_setjmp
, regno
));
2285 /* Add MEM to PBI->MEM_SET_LIST. MEM should be canonical. Respect the
2286 maximal list size; look for overlaps in mode and select the largest. */
2288 add_to_mem_set_list (pbi
, mem
)
2289 struct propagate_block_info
*pbi
;
2294 /* We don't know how large a BLKmode store is, so we must not
2295 take them into consideration. */
2296 if (GET_MODE (mem
) == BLKmode
)
2299 for (i
= pbi
->mem_set_list
; i
; i
= XEXP (i
, 1))
2301 rtx e
= XEXP (i
, 0);
2302 if (rtx_equal_p (XEXP (mem
, 0), XEXP (e
, 0)))
2304 if (GET_MODE_SIZE (GET_MODE (mem
)) > GET_MODE_SIZE (GET_MODE (e
)))
2307 /* If we must store a copy of the mem, we can just modify
2308 the mode of the stored copy. */
2309 if (pbi
->flags
& PROP_AUTOINC
)
2310 PUT_MODE (e
, GET_MODE (mem
));
2319 if (pbi
->mem_set_list_len
< MAX_MEM_SET_LIST_LEN
)
2322 /* Store a copy of mem, otherwise the address may be
2323 scrogged by find_auto_inc. */
2324 if (pbi
->flags
& PROP_AUTOINC
)
2325 mem
= shallow_copy_rtx (mem
);
2327 pbi
->mem_set_list
= alloc_EXPR_LIST (0, mem
, pbi
->mem_set_list
);
2328 pbi
->mem_set_list_len
++;
2332 /* INSN references memory, possibly using autoincrement addressing modes.
2333 Find any entries on the mem_set_list that need to be invalidated due
2334 to an address change. */
2337 invalidate_mems_from_autoinc (pbi
, insn
)
2338 struct propagate_block_info
*pbi
;
2341 rtx note
= REG_NOTES (insn
);
2342 for (note
= REG_NOTES (insn
); note
; note
= XEXP (note
, 1))
2343 if (REG_NOTE_KIND (note
) == REG_INC
)
2344 invalidate_mems_from_set (pbi
, XEXP (note
, 0));
2347 /* EXP is a REG. Remove any dependent entries from pbi->mem_set_list. */
2350 invalidate_mems_from_set (pbi
, exp
)
2351 struct propagate_block_info
*pbi
;
2354 rtx temp
= pbi
->mem_set_list
;
2355 rtx prev
= NULL_RTX
;
2360 next
= XEXP (temp
, 1);
2361 if (reg_overlap_mentioned_p (exp
, XEXP (temp
, 0)))
2363 /* Splice this entry out of the list. */
2365 XEXP (prev
, 1) = next
;
2367 pbi
->mem_set_list
= next
;
2368 free_EXPR_LIST_node (temp
);
2369 pbi
->mem_set_list_len
--;
2377 /* Process the registers that are set within X. Their bits are set to
2378 1 in the regset DEAD, because they are dead prior to this insn.
2380 If INSN is nonzero, it is the insn being processed.
2382 FLAGS is the set of operations to perform. */
2385 mark_set_regs (pbi
, x
, insn
)
2386 struct propagate_block_info
*pbi
;
2389 rtx cond
= NULL_RTX
;
2394 for (link
= REG_NOTES (insn
); link
; link
= XEXP (link
, 1))
2396 if (REG_NOTE_KIND (link
) == REG_INC
)
2397 mark_set_1 (pbi
, SET
, XEXP (link
, 0),
2398 (GET_CODE (x
) == COND_EXEC
2399 ? COND_EXEC_TEST (x
) : NULL_RTX
),
2403 switch (code
= GET_CODE (x
))
2407 mark_set_1 (pbi
, code
, SET_DEST (x
), cond
, insn
, pbi
->flags
);
2411 cond
= COND_EXEC_TEST (x
);
2412 x
= COND_EXEC_CODE (x
);
2419 for (i
= XVECLEN (x
, 0) - 1; i
>= 0; i
--)
2421 rtx sub
= XVECEXP (x
, 0, i
);
2422 switch (code
= GET_CODE (sub
))
2425 if (cond
!= NULL_RTX
)
2428 cond
= COND_EXEC_TEST (sub
);
2429 sub
= COND_EXEC_CODE (sub
);
2430 if (GET_CODE (sub
) != SET
&& GET_CODE (sub
) != CLOBBER
)
2436 mark_set_1 (pbi
, code
, SET_DEST (sub
), cond
, insn
, pbi
->flags
);
2451 /* Process a single set, which appears in INSN. REG (which may not
2452 actually be a REG, it may also be a SUBREG, PARALLEL, etc.) is
2453 being set using the CODE (which may be SET, CLOBBER, or COND_EXEC).
2454 If the set is conditional (because it appear in a COND_EXEC), COND
2455 will be the condition. */
2458 mark_set_1 (pbi
, code
, reg
, cond
, insn
, flags
)
2459 struct propagate_block_info
*pbi
;
2461 rtx reg
, cond
, insn
;
2464 int regno_first
= -1, regno_last
= -1;
2465 unsigned long not_dead
= 0;
2468 /* Modifying just one hardware register of a multi-reg value or just a
2469 byte field of a register does not mean the value from before this insn
2470 is now dead. Of course, if it was dead after it's unused now. */
2472 switch (GET_CODE (reg
))
2475 /* Some targets place small structures in registers for return values of
2476 functions. We have to detect this case specially here to get correct
2477 flow information. */
2478 for (i
= XVECLEN (reg
, 0) - 1; i
>= 0; i
--)
2479 if (XEXP (XVECEXP (reg
, 0, i
), 0) != 0)
2480 mark_set_1 (pbi
, code
, XEXP (XVECEXP (reg
, 0, i
), 0), cond
, insn
,
2486 case STRICT_LOW_PART
:
2487 /* ??? Assumes STRICT_LOW_PART not used on multi-word registers. */
2489 reg
= XEXP (reg
, 0);
2490 while (GET_CODE (reg
) == SUBREG
2491 || GET_CODE (reg
) == ZERO_EXTRACT
2492 || GET_CODE (reg
) == SIGN_EXTRACT
2493 || GET_CODE (reg
) == STRICT_LOW_PART
);
2494 if (GET_CODE (reg
) == MEM
)
2496 not_dead
= (unsigned long) REGNO_REG_SET_P (pbi
->reg_live
, REGNO (reg
));
2500 regno_last
= regno_first
= REGNO (reg
);
2501 if (regno_first
< FIRST_PSEUDO_REGISTER
)
2502 regno_last
+= HARD_REGNO_NREGS (regno_first
, GET_MODE (reg
)) - 1;
2506 if (GET_CODE (SUBREG_REG (reg
)) == REG
)
2508 enum machine_mode outer_mode
= GET_MODE (reg
);
2509 enum machine_mode inner_mode
= GET_MODE (SUBREG_REG (reg
));
2511 /* Identify the range of registers affected. This is moderately
2512 tricky for hard registers. See alter_subreg. */
2514 regno_last
= regno_first
= REGNO (SUBREG_REG (reg
));
2515 if (regno_first
< FIRST_PSEUDO_REGISTER
)
2517 regno_first
+= subreg_regno_offset (regno_first
, inner_mode
,
2520 regno_last
= (regno_first
2521 + HARD_REGNO_NREGS (regno_first
, outer_mode
) - 1);
2523 /* Since we've just adjusted the register number ranges, make
2524 sure REG matches. Otherwise some_was_live will be clear
2525 when it shouldn't have been, and we'll create incorrect
2526 REG_UNUSED notes. */
2527 reg
= gen_rtx_REG (outer_mode
, regno_first
);
2531 /* If the number of words in the subreg is less than the number
2532 of words in the full register, we have a well-defined partial
2533 set. Otherwise the high bits are undefined.
2535 This is only really applicable to pseudos, since we just took
2536 care of multi-word hard registers. */
2537 if (((GET_MODE_SIZE (outer_mode
)
2538 + UNITS_PER_WORD
- 1) / UNITS_PER_WORD
)
2539 < ((GET_MODE_SIZE (inner_mode
)
2540 + UNITS_PER_WORD
- 1) / UNITS_PER_WORD
))
2541 not_dead
= (unsigned long) REGNO_REG_SET_P (pbi
->reg_live
,
2544 reg
= SUBREG_REG (reg
);
2548 reg
= SUBREG_REG (reg
);
2555 /* If this set is a MEM, then it kills any aliased writes.
2556 If this set is a REG, then it kills any MEMs which use the reg. */
2557 if (optimize
&& (flags
& PROP_SCAN_DEAD_CODE
))
2559 if (GET_CODE (reg
) == REG
)
2560 invalidate_mems_from_set (pbi
, reg
);
2562 /* If the memory reference had embedded side effects (autoincrement
2563 address modes. Then we may need to kill some entries on the
2565 if (insn
&& GET_CODE (reg
) == MEM
)
2566 invalidate_mems_from_autoinc (pbi
, insn
);
2568 if (GET_CODE (reg
) == MEM
&& ! side_effects_p (reg
)
2569 /* ??? With more effort we could track conditional memory life. */
2571 /* There are no REG_INC notes for SP, so we can't assume we'll see
2572 everything that invalidates it. To be safe, don't eliminate any
2573 stores though SP; none of them should be redundant anyway. */
2574 && ! reg_mentioned_p (stack_pointer_rtx
, reg
))
2575 add_to_mem_set_list (pbi
, canon_rtx (reg
));
2578 if (GET_CODE (reg
) == REG
2579 && ! (regno_first
== FRAME_POINTER_REGNUM
2580 && (! reload_completed
|| frame_pointer_needed
))
2581 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
2582 && ! (regno_first
== HARD_FRAME_POINTER_REGNUM
2583 && (! reload_completed
|| frame_pointer_needed
))
2585 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
2586 && ! (regno_first
== ARG_POINTER_REGNUM
&& fixed_regs
[regno_first
])
2590 int some_was_live
= 0, some_was_dead
= 0;
2592 for (i
= regno_first
; i
<= regno_last
; ++i
)
2594 int needed_regno
= REGNO_REG_SET_P (pbi
->reg_live
, i
);
2597 /* Order of the set operation matters here since both
2598 sets may be the same. */
2599 CLEAR_REGNO_REG_SET (pbi
->cond_local_set
, i
);
2600 if (cond
!= NULL_RTX
2601 && ! REGNO_REG_SET_P (pbi
->local_set
, i
))
2602 SET_REGNO_REG_SET (pbi
->cond_local_set
, i
);
2604 SET_REGNO_REG_SET (pbi
->local_set
, i
);
2606 if (code
!= CLOBBER
)
2607 SET_REGNO_REG_SET (pbi
->new_set
, i
);
2609 some_was_live
|= needed_regno
;
2610 some_was_dead
|= ! needed_regno
;
2613 #ifdef HAVE_conditional_execution
2614 /* Consider conditional death in deciding that the register needs
2616 if (some_was_live
&& ! not_dead
2617 /* The stack pointer is never dead. Well, not strictly true,
2618 but it's very difficult to tell from here. Hopefully
2619 combine_stack_adjustments will fix up the most egregious
2621 && regno_first
!= STACK_POINTER_REGNUM
)
2623 for (i
= regno_first
; i
<= regno_last
; ++i
)
2624 if (! mark_regno_cond_dead (pbi
, i
, cond
))
2625 not_dead
|= ((unsigned long) 1) << (i
- regno_first
);
2629 /* Additional data to record if this is the final pass. */
2630 if (flags
& (PROP_LOG_LINKS
| PROP_REG_INFO
2631 | PROP_DEATH_NOTES
| PROP_AUTOINC
))
2634 int blocknum
= pbi
->bb
->index
;
2637 if (flags
& (PROP_LOG_LINKS
| PROP_AUTOINC
))
2639 y
= pbi
->reg_next_use
[regno_first
];
2641 /* The next use is no longer next, since a store intervenes. */
2642 for (i
= regno_first
; i
<= regno_last
; ++i
)
2643 pbi
->reg_next_use
[i
] = 0;
2646 if (flags
& PROP_REG_INFO
)
2648 for (i
= regno_first
; i
<= regno_last
; ++i
)
2650 /* Count (weighted) references, stores, etc. This counts a
2651 register twice if it is modified, but that is correct. */
2652 REG_N_SETS (i
) += 1;
2653 REG_N_REFS (i
) += 1;
2654 REG_FREQ (i
) += REG_FREQ_FROM_BB (pbi
->bb
);
2656 /* The insns where a reg is live are normally counted
2657 elsewhere, but we want the count to include the insn
2658 where the reg is set, and the normal counting mechanism
2659 would not count it. */
2660 REG_LIVE_LENGTH (i
) += 1;
2663 /* If this is a hard reg, record this function uses the reg. */
2664 if (regno_first
< FIRST_PSEUDO_REGISTER
)
2666 for (i
= regno_first
; i
<= regno_last
; i
++)
2667 regs_ever_live
[i
] = 1;
2671 /* Keep track of which basic blocks each reg appears in. */
2672 if (REG_BASIC_BLOCK (regno_first
) == REG_BLOCK_UNKNOWN
)
2673 REG_BASIC_BLOCK (regno_first
) = blocknum
;
2674 else if (REG_BASIC_BLOCK (regno_first
) != blocknum
)
2675 REG_BASIC_BLOCK (regno_first
) = REG_BLOCK_GLOBAL
;
2679 if (! some_was_dead
)
2681 if (flags
& PROP_LOG_LINKS
)
2683 /* Make a logical link from the next following insn
2684 that uses this register, back to this insn.
2685 The following insns have already been processed.
2687 We don't build a LOG_LINK for hard registers containing
2688 in ASM_OPERANDs. If these registers get replaced,
2689 we might wind up changing the semantics of the insn,
2690 even if reload can make what appear to be valid
2691 assignments later. */
2692 if (y
&& (BLOCK_NUM (y
) == blocknum
)
2693 && (regno_first
>= FIRST_PSEUDO_REGISTER
2694 || asm_noperands (PATTERN (y
)) < 0))
2695 LOG_LINKS (y
) = alloc_INSN_LIST (insn
, LOG_LINKS (y
));
2700 else if (! some_was_live
)
2702 if (flags
& PROP_REG_INFO
)
2703 REG_N_DEATHS (regno_first
) += 1;
2705 if (flags
& PROP_DEATH_NOTES
)
2707 /* Note that dead stores have already been deleted
2708 when possible. If we get here, we have found a
2709 dead store that cannot be eliminated (because the
2710 same insn does something useful). Indicate this
2711 by marking the reg being set as dying here. */
2713 = alloc_EXPR_LIST (REG_UNUSED
, reg
, REG_NOTES (insn
));
2718 if (flags
& PROP_DEATH_NOTES
)
2720 /* This is a case where we have a multi-word hard register
2721 and some, but not all, of the words of the register are
2722 needed in subsequent insns. Write REG_UNUSED notes
2723 for those parts that were not needed. This case should
2726 for (i
= regno_first
; i
<= regno_last
; ++i
)
2727 if (! REGNO_REG_SET_P (pbi
->reg_live
, i
))
2729 = alloc_EXPR_LIST (REG_UNUSED
,
2730 gen_rtx_REG (reg_raw_mode
[i
], i
),
2736 /* Mark the register as being dead. */
2738 /* The stack pointer is never dead. Well, not strictly true,
2739 but it's very difficult to tell from here. Hopefully
2740 combine_stack_adjustments will fix up the most egregious
2742 && regno_first
!= STACK_POINTER_REGNUM
)
2744 for (i
= regno_first
; i
<= regno_last
; ++i
)
2745 if (!(not_dead
& (((unsigned long) 1) << (i
- regno_first
))))
2746 CLEAR_REGNO_REG_SET (pbi
->reg_live
, i
);
2749 else if (GET_CODE (reg
) == REG
)
2751 if (flags
& (PROP_LOG_LINKS
| PROP_AUTOINC
))
2752 pbi
->reg_next_use
[regno_first
] = 0;
2755 /* If this is the last pass and this is a SCRATCH, show it will be dying
2756 here and count it. */
2757 else if (GET_CODE (reg
) == SCRATCH
)
2759 if (flags
& PROP_DEATH_NOTES
)
2761 = alloc_EXPR_LIST (REG_UNUSED
, reg
, REG_NOTES (insn
));
2765 #ifdef HAVE_conditional_execution
2766 /* Mark REGNO conditionally dead.
2767 Return true if the register is now unconditionally dead. */
2770 mark_regno_cond_dead (pbi
, regno
, cond
)
2771 struct propagate_block_info
*pbi
;
2775 /* If this is a store to a predicate register, the value of the
2776 predicate is changing, we don't know that the predicate as seen
2777 before is the same as that seen after. Flush all dependent
2778 conditions from reg_cond_dead. This will make all such
2779 conditionally live registers unconditionally live. */
2780 if (REGNO_REG_SET_P (pbi
->reg_cond_reg
, regno
))
2781 flush_reg_cond_reg (pbi
, regno
);
2783 /* If this is an unconditional store, remove any conditional
2784 life that may have existed. */
2785 if (cond
== NULL_RTX
)
2786 splay_tree_remove (pbi
->reg_cond_dead
, regno
);
2789 splay_tree_node node
;
2790 struct reg_cond_life_info
*rcli
;
2793 /* Otherwise this is a conditional set. Record that fact.
2794 It may have been conditionally used, or there may be a
2795 subsequent set with a complimentary condition. */
2797 node
= splay_tree_lookup (pbi
->reg_cond_dead
, regno
);
2800 /* The register was unconditionally live previously.
2801 Record the current condition as the condition under
2802 which it is dead. */
2803 rcli
= (struct reg_cond_life_info
*) xmalloc (sizeof (*rcli
));
2804 rcli
->condition
= cond
;
2805 rcli
->stores
= cond
;
2806 rcli
->orig_condition
= const0_rtx
;
2807 splay_tree_insert (pbi
->reg_cond_dead
, regno
,
2808 (splay_tree_value
) rcli
);
2810 SET_REGNO_REG_SET (pbi
->reg_cond_reg
, REGNO (XEXP (cond
, 0)));
2812 /* Not unconditionally dead. */
2817 /* The register was conditionally live previously.
2818 Add the new condition to the old. */
2819 rcli
= (struct reg_cond_life_info
*) node
->value
;
2820 ncond
= rcli
->condition
;
2821 ncond
= ior_reg_cond (ncond
, cond
, 1);
2822 if (rcli
->stores
== const0_rtx
)
2823 rcli
->stores
= cond
;
2824 else if (rcli
->stores
!= const1_rtx
)
2825 rcli
->stores
= ior_reg_cond (rcli
->stores
, cond
, 1);
2827 /* If the register is now unconditionally dead, remove the entry
2828 in the splay_tree. A register is unconditionally dead if the
2829 dead condition ncond is true. A register is also unconditionally
2830 dead if the sum of all conditional stores is an unconditional
2831 store (stores is true), and the dead condition is identically the
2832 same as the original dead condition initialized at the end of
2833 the block. This is a pointer compare, not an rtx_equal_p
2835 if (ncond
== const1_rtx
2836 || (ncond
== rcli
->orig_condition
&& rcli
->stores
== const1_rtx
))
2837 splay_tree_remove (pbi
->reg_cond_dead
, regno
);
2840 rcli
->condition
= ncond
;
2842 SET_REGNO_REG_SET (pbi
->reg_cond_reg
, REGNO (XEXP (cond
, 0)));
2844 /* Not unconditionally dead. */
2853 /* Called from splay_tree_delete for pbi->reg_cond_life. */
2856 free_reg_cond_life_info (value
)
2857 splay_tree_value value
;
2859 struct reg_cond_life_info
*rcli
= (struct reg_cond_life_info
*) value
;
2863 /* Helper function for flush_reg_cond_reg. */
2866 flush_reg_cond_reg_1 (node
, data
)
2867 splay_tree_node node
;
2870 struct reg_cond_life_info
*rcli
;
2871 int *xdata
= (int *) data
;
2872 unsigned int regno
= xdata
[0];
2874 /* Don't need to search if last flushed value was farther on in
2875 the in-order traversal. */
2876 if (xdata
[1] >= (int) node
->key
)
2879 /* Splice out portions of the expression that refer to regno. */
2880 rcli
= (struct reg_cond_life_info
*) node
->value
;
2881 rcli
->condition
= elim_reg_cond (rcli
->condition
, regno
);
2882 if (rcli
->stores
!= const0_rtx
&& rcli
->stores
!= const1_rtx
)
2883 rcli
->stores
= elim_reg_cond (rcli
->stores
, regno
);
2885 /* If the entire condition is now false, signal the node to be removed. */
2886 if (rcli
->condition
== const0_rtx
)
2888 xdata
[1] = node
->key
;
2891 else if (rcli
->condition
== const1_rtx
)
2897 /* Flush all (sub) expressions referring to REGNO from REG_COND_LIVE. */
2900 flush_reg_cond_reg (pbi
, regno
)
2901 struct propagate_block_info
*pbi
;
2908 while (splay_tree_foreach (pbi
->reg_cond_dead
,
2909 flush_reg_cond_reg_1
, pair
) == -1)
2910 splay_tree_remove (pbi
->reg_cond_dead
, pair
[1]);
2912 CLEAR_REGNO_REG_SET (pbi
->reg_cond_reg
, regno
);
2915 /* Logical arithmetic on predicate conditions. IOR, NOT and AND.
2916 For ior/and, the ADD flag determines whether we want to add the new
2917 condition X to the old one unconditionally. If it is zero, we will
2918 only return a new expression if X allows us to simplify part of
2919 OLD, otherwise we return NULL to the caller.
2920 If ADD is nonzero, we will return a new condition in all cases. The
2921 toplevel caller of one of these functions should always pass 1 for
2925 ior_reg_cond (old
, x
, add
)
2931 if (GET_RTX_CLASS (GET_CODE (old
)) == '<')
2933 if (GET_RTX_CLASS (GET_CODE (x
)) == '<'
2934 && REVERSE_CONDEXEC_PREDICATES_P (GET_CODE (x
), GET_CODE (old
))
2935 && REGNO (XEXP (x
, 0)) == REGNO (XEXP (old
, 0)))
2937 if (GET_CODE (x
) == GET_CODE (old
)
2938 && REGNO (XEXP (x
, 0)) == REGNO (XEXP (old
, 0)))
2942 return gen_rtx_IOR (0, old
, x
);
2945 switch (GET_CODE (old
))
2948 op0
= ior_reg_cond (XEXP (old
, 0), x
, 0);
2949 op1
= ior_reg_cond (XEXP (old
, 1), x
, 0);
2950 if (op0
!= NULL
|| op1
!= NULL
)
2952 if (op0
== const0_rtx
)
2953 return op1
? op1
: gen_rtx_IOR (0, XEXP (old
, 1), x
);
2954 if (op1
== const0_rtx
)
2955 return op0
? op0
: gen_rtx_IOR (0, XEXP (old
, 0), x
);
2956 if (op0
== const1_rtx
|| op1
== const1_rtx
)
2959 op0
= gen_rtx_IOR (0, XEXP (old
, 0), x
);
2960 else if (rtx_equal_p (x
, op0
))
2961 /* (x | A) | x ~ (x | A). */
2964 op1
= gen_rtx_IOR (0, XEXP (old
, 1), x
);
2965 else if (rtx_equal_p (x
, op1
))
2966 /* (A | x) | x ~ (A | x). */
2968 return gen_rtx_IOR (0, op0
, op1
);
2972 return gen_rtx_IOR (0, old
, x
);
2975 op0
= ior_reg_cond (XEXP (old
, 0), x
, 0);
2976 op1
= ior_reg_cond (XEXP (old
, 1), x
, 0);
2977 if (op0
!= NULL
|| op1
!= NULL
)
2979 if (op0
== const1_rtx
)
2980 return op1
? op1
: gen_rtx_IOR (0, XEXP (old
, 1), x
);
2981 if (op1
== const1_rtx
)
2982 return op0
? op0
: gen_rtx_IOR (0, XEXP (old
, 0), x
);
2983 if (op0
== const0_rtx
|| op1
== const0_rtx
)
2986 op0
= gen_rtx_IOR (0, XEXP (old
, 0), x
);
2987 else if (rtx_equal_p (x
, op0
))
2988 /* (x & A) | x ~ x. */
2991 op1
= gen_rtx_IOR (0, XEXP (old
, 1), x
);
2992 else if (rtx_equal_p (x
, op1
))
2993 /* (A & x) | x ~ x. */
2995 return gen_rtx_AND (0, op0
, op1
);
2999 return gen_rtx_IOR (0, old
, x
);
3002 op0
= and_reg_cond (XEXP (old
, 0), not_reg_cond (x
), 0);
3004 return not_reg_cond (op0
);
3007 return gen_rtx_IOR (0, old
, x
);
3018 enum rtx_code x_code
;
3020 if (x
== const0_rtx
)
3022 else if (x
== const1_rtx
)
3024 x_code
= GET_CODE (x
);
3027 if (GET_RTX_CLASS (x_code
) == '<'
3028 && GET_CODE (XEXP (x
, 0)) == REG
)
3030 if (XEXP (x
, 1) != const0_rtx
)
3033 return gen_rtx_fmt_ee (reverse_condition (x_code
),
3034 VOIDmode
, XEXP (x
, 0), const0_rtx
);
3036 return gen_rtx_NOT (0, x
);
3040 and_reg_cond (old
, x
, add
)
3046 if (GET_RTX_CLASS (GET_CODE (old
)) == '<')
3048 if (GET_RTX_CLASS (GET_CODE (x
)) == '<'
3049 && GET_CODE (x
) == reverse_condition (GET_CODE (old
))
3050 && REGNO (XEXP (x
, 0)) == REGNO (XEXP (old
, 0)))
3052 if (GET_CODE (x
) == GET_CODE (old
)
3053 && REGNO (XEXP (x
, 0)) == REGNO (XEXP (old
, 0)))
3057 return gen_rtx_AND (0, old
, x
);
3060 switch (GET_CODE (old
))
3063 op0
= and_reg_cond (XEXP (old
, 0), x
, 0);
3064 op1
= and_reg_cond (XEXP (old
, 1), x
, 0);
3065 if (op0
!= NULL
|| op1
!= NULL
)
3067 if (op0
== const0_rtx
)
3068 return op1
? op1
: gen_rtx_AND (0, XEXP (old
, 1), x
);
3069 if (op1
== const0_rtx
)
3070 return op0
? op0
: gen_rtx_AND (0, XEXP (old
, 0), x
);
3071 if (op0
== const1_rtx
|| op1
== const1_rtx
)
3074 op0
= gen_rtx_AND (0, XEXP (old
, 0), x
);
3075 else if (rtx_equal_p (x
, op0
))
3076 /* (x | A) & x ~ x. */
3079 op1
= gen_rtx_AND (0, XEXP (old
, 1), x
);
3080 else if (rtx_equal_p (x
, op1
))
3081 /* (A | x) & x ~ x. */
3083 return gen_rtx_IOR (0, op0
, op1
);
3087 return gen_rtx_AND (0, old
, x
);
3090 op0
= and_reg_cond (XEXP (old
, 0), x
, 0);
3091 op1
= and_reg_cond (XEXP (old
, 1), x
, 0);
3092 if (op0
!= NULL
|| op1
!= NULL
)
3094 if (op0
== const1_rtx
)
3095 return op1
? op1
: gen_rtx_AND (0, XEXP (old
, 1), x
);
3096 if (op1
== const1_rtx
)
3097 return op0
? op0
: gen_rtx_AND (0, XEXP (old
, 0), x
);
3098 if (op0
== const0_rtx
|| op1
== const0_rtx
)
3101 op0
= gen_rtx_AND (0, XEXP (old
, 0), x
);
3102 else if (rtx_equal_p (x
, op0
))
3103 /* (x & A) & x ~ (x & A). */
3106 op1
= gen_rtx_AND (0, XEXP (old
, 1), x
);
3107 else if (rtx_equal_p (x
, op1
))
3108 /* (A & x) & x ~ (A & x). */
3110 return gen_rtx_AND (0, op0
, op1
);
3114 return gen_rtx_AND (0, old
, x
);
3117 op0
= ior_reg_cond (XEXP (old
, 0), not_reg_cond (x
), 0);
3119 return not_reg_cond (op0
);
3122 return gen_rtx_AND (0, old
, x
);
3129 /* Given a condition X, remove references to reg REGNO and return the
3130 new condition. The removal will be done so that all conditions
3131 involving REGNO are considered to evaluate to false. This function
3132 is used when the value of REGNO changes. */
3135 elim_reg_cond (x
, regno
)
3141 if (GET_RTX_CLASS (GET_CODE (x
)) == '<')
3143 if (REGNO (XEXP (x
, 0)) == regno
)
3148 switch (GET_CODE (x
))
3151 op0
= elim_reg_cond (XEXP (x
, 0), regno
);
3152 op1
= elim_reg_cond (XEXP (x
, 1), regno
);
3153 if (op0
== const0_rtx
|| op1
== const0_rtx
)
3155 if (op0
== const1_rtx
)
3157 if (op1
== const1_rtx
)
3159 if (op0
== XEXP (x
, 0) && op1
== XEXP (x
, 1))
3161 return gen_rtx_AND (0, op0
, op1
);
3164 op0
= elim_reg_cond (XEXP (x
, 0), regno
);
3165 op1
= elim_reg_cond (XEXP (x
, 1), regno
);
3166 if (op0
== const1_rtx
|| op1
== const1_rtx
)
3168 if (op0
== const0_rtx
)
3170 if (op1
== const0_rtx
)
3172 if (op0
== XEXP (x
, 0) && op1
== XEXP (x
, 1))
3174 return gen_rtx_IOR (0, op0
, op1
);
3177 op0
= elim_reg_cond (XEXP (x
, 0), regno
);
3178 if (op0
== const0_rtx
)
3180 if (op0
== const1_rtx
)
3182 if (op0
!= XEXP (x
, 0))
3183 return not_reg_cond (op0
);
3190 #endif /* HAVE_conditional_execution */
3194 /* Try to substitute the auto-inc expression INC as the address inside
3195 MEM which occurs in INSN. Currently, the address of MEM is an expression
3196 involving INCR_REG, and INCR is the next use of INCR_REG; it is an insn
3197 that has a single set whose source is a PLUS of INCR_REG and something
3201 attempt_auto_inc (pbi
, inc
, insn
, mem
, incr
, incr_reg
)
3202 struct propagate_block_info
*pbi
;
3203 rtx inc
, insn
, mem
, incr
, incr_reg
;
3205 int regno
= REGNO (incr_reg
);
3206 rtx set
= single_set (incr
);
3207 rtx q
= SET_DEST (set
);
3208 rtx y
= SET_SRC (set
);
3209 int opnum
= XEXP (y
, 0) == incr_reg
? 0 : 1;
3211 /* Make sure this reg appears only once in this insn. */
3212 if (count_occurrences (PATTERN (insn
), incr_reg
, 1) != 1)
3215 if (dead_or_set_p (incr
, incr_reg
)
3216 /* Mustn't autoinc an eliminable register. */
3217 && (regno
>= FIRST_PSEUDO_REGISTER
3218 || ! TEST_HARD_REG_BIT (elim_reg_set
, regno
)))
3220 /* This is the simple case. Try to make the auto-inc. If
3221 we can't, we are done. Otherwise, we will do any
3222 needed updates below. */
3223 if (! validate_change (insn
, &XEXP (mem
, 0), inc
, 0))
3226 else if (GET_CODE (q
) == REG
3227 /* PREV_INSN used here to check the semi-open interval
3229 && ! reg_used_between_p (q
, PREV_INSN (insn
), incr
)
3230 /* We must also check for sets of q as q may be
3231 a call clobbered hard register and there may
3232 be a call between PREV_INSN (insn) and incr. */
3233 && ! reg_set_between_p (q
, PREV_INSN (insn
), incr
))
3235 /* We have *p followed sometime later by q = p+size.
3236 Both p and q must be live afterward,
3237 and q is not used between INSN and its assignment.
3238 Change it to q = p, ...*q..., q = q+size.
3239 Then fall into the usual case. */
3243 emit_move_insn (q
, incr_reg
);
3244 insns
= get_insns ();
3247 /* If we can't make the auto-inc, or can't make the
3248 replacement into Y, exit. There's no point in making
3249 the change below if we can't do the auto-inc and doing
3250 so is not correct in the pre-inc case. */
3253 validate_change (insn
, &XEXP (mem
, 0), inc
, 1);
3254 validate_change (incr
, &XEXP (y
, opnum
), q
, 1);
3255 if (! apply_change_group ())
3258 /* We now know we'll be doing this change, so emit the
3259 new insn(s) and do the updates. */
3260 emit_insns_before (insns
, insn
);
3262 if (pbi
->bb
->head
== insn
)
3263 pbi
->bb
->head
= insns
;
3265 /* INCR will become a NOTE and INSN won't contain a
3266 use of INCR_REG. If a use of INCR_REG was just placed in
3267 the insn before INSN, make that the next use.
3268 Otherwise, invalidate it. */
3269 if (GET_CODE (PREV_INSN (insn
)) == INSN
3270 && GET_CODE (PATTERN (PREV_INSN (insn
))) == SET
3271 && SET_SRC (PATTERN (PREV_INSN (insn
))) == incr_reg
)
3272 pbi
->reg_next_use
[regno
] = PREV_INSN (insn
);
3274 pbi
->reg_next_use
[regno
] = 0;
3279 /* REGNO is now used in INCR which is below INSN, but
3280 it previously wasn't live here. If we don't mark
3281 it as live, we'll put a REG_DEAD note for it
3282 on this insn, which is incorrect. */
3283 SET_REGNO_REG_SET (pbi
->reg_live
, regno
);
3285 /* If there are any calls between INSN and INCR, show
3286 that REGNO now crosses them. */
3287 for (temp
= insn
; temp
!= incr
; temp
= NEXT_INSN (temp
))
3288 if (GET_CODE (temp
) == CALL_INSN
)
3289 REG_N_CALLS_CROSSED (regno
)++;
3291 /* Invalidate alias info for Q since we just changed its value. */
3292 clear_reg_alias_info (q
);
3297 /* If we haven't returned, it means we were able to make the
3298 auto-inc, so update the status. First, record that this insn
3299 has an implicit side effect. */
3301 REG_NOTES (insn
) = alloc_EXPR_LIST (REG_INC
, incr_reg
, REG_NOTES (insn
));
3303 /* Modify the old increment-insn to simply copy
3304 the already-incremented value of our register. */
3305 if (! validate_change (incr
, &SET_SRC (set
), incr_reg
, 0))
3308 /* If that makes it a no-op (copying the register into itself) delete
3309 it so it won't appear to be a "use" and a "set" of this
3311 if (REGNO (SET_DEST (set
)) == REGNO (incr_reg
))
3313 /* If the original source was dead, it's dead now. */
3316 while ((note
= find_reg_note (incr
, REG_DEAD
, NULL_RTX
)) != NULL_RTX
)
3318 remove_note (incr
, note
);
3319 if (XEXP (note
, 0) != incr_reg
)
3320 CLEAR_REGNO_REG_SET (pbi
->reg_live
, REGNO (XEXP (note
, 0)));
3323 PUT_CODE (incr
, NOTE
);
3324 NOTE_LINE_NUMBER (incr
) = NOTE_INSN_DELETED
;
3325 NOTE_SOURCE_FILE (incr
) = 0;
3328 if (regno
>= FIRST_PSEUDO_REGISTER
)
3330 /* Count an extra reference to the reg. When a reg is
3331 incremented, spilling it is worse, so we want to make
3332 that less likely. */
3333 REG_FREQ (regno
) += REG_FREQ_FROM_BB (pbi
->bb
);
3335 /* Count the increment as a setting of the register,
3336 even though it isn't a SET in rtl. */
3337 REG_N_SETS (regno
)++;
3341 /* X is a MEM found in INSN. See if we can convert it into an auto-increment
3345 find_auto_inc (pbi
, x
, insn
)
3346 struct propagate_block_info
*pbi
;
3350 rtx addr
= XEXP (x
, 0);
3351 HOST_WIDE_INT offset
= 0;
3352 rtx set
, y
, incr
, inc_val
;
3354 int size
= GET_MODE_SIZE (GET_MODE (x
));
3356 if (GET_CODE (insn
) == JUMP_INSN
)
3359 /* Here we detect use of an index register which might be good for
3360 postincrement, postdecrement, preincrement, or predecrement. */
3362 if (GET_CODE (addr
) == PLUS
&& GET_CODE (XEXP (addr
, 1)) == CONST_INT
)
3363 offset
= INTVAL (XEXP (addr
, 1)), addr
= XEXP (addr
, 0);
3365 if (GET_CODE (addr
) != REG
)
3368 regno
= REGNO (addr
);
3370 /* Is the next use an increment that might make auto-increment? */
3371 incr
= pbi
->reg_next_use
[regno
];
3372 if (incr
== 0 || BLOCK_NUM (incr
) != BLOCK_NUM (insn
))
3374 set
= single_set (incr
);
3375 if (set
== 0 || GET_CODE (set
) != SET
)
3379 if (GET_CODE (y
) != PLUS
)
3382 if (REG_P (XEXP (y
, 0)) && REGNO (XEXP (y
, 0)) == REGNO (addr
))
3383 inc_val
= XEXP (y
, 1);
3384 else if (REG_P (XEXP (y
, 1)) && REGNO (XEXP (y
, 1)) == REGNO (addr
))
3385 inc_val
= XEXP (y
, 0);
3389 if (GET_CODE (inc_val
) == CONST_INT
)
3391 if (HAVE_POST_INCREMENT
3392 && (INTVAL (inc_val
) == size
&& offset
== 0))
3393 attempt_auto_inc (pbi
, gen_rtx_POST_INC (Pmode
, addr
), insn
, x
,
3395 else if (HAVE_POST_DECREMENT
3396 && (INTVAL (inc_val
) == -size
&& offset
== 0))
3397 attempt_auto_inc (pbi
, gen_rtx_POST_DEC (Pmode
, addr
), insn
, x
,
3399 else if (HAVE_PRE_INCREMENT
3400 && (INTVAL (inc_val
) == size
&& offset
== size
))
3401 attempt_auto_inc (pbi
, gen_rtx_PRE_INC (Pmode
, addr
), insn
, x
,
3403 else if (HAVE_PRE_DECREMENT
3404 && (INTVAL (inc_val
) == -size
&& offset
== -size
))
3405 attempt_auto_inc (pbi
, gen_rtx_PRE_DEC (Pmode
, addr
), insn
, x
,
3407 else if (HAVE_POST_MODIFY_DISP
&& offset
== 0)
3408 attempt_auto_inc (pbi
, gen_rtx_POST_MODIFY (Pmode
, addr
,
3409 gen_rtx_PLUS (Pmode
,
3412 insn
, x
, incr
, addr
);
3414 else if (GET_CODE (inc_val
) == REG
3415 && ! reg_set_between_p (inc_val
, PREV_INSN (insn
),
3419 if (HAVE_POST_MODIFY_REG
&& offset
== 0)
3420 attempt_auto_inc (pbi
, gen_rtx_POST_MODIFY (Pmode
, addr
,
3421 gen_rtx_PLUS (Pmode
,
3424 insn
, x
, incr
, addr
);
3428 #endif /* AUTO_INC_DEC */
3431 mark_used_reg (pbi
, reg
, cond
, insn
)
3432 struct propagate_block_info
*pbi
;
3434 rtx cond ATTRIBUTE_UNUSED
;
3437 unsigned int regno_first
, regno_last
, i
;
3438 int some_was_live
, some_was_dead
, some_not_set
;
3440 regno_last
= regno_first
= REGNO (reg
);
3441 if (regno_first
< FIRST_PSEUDO_REGISTER
)
3442 regno_last
+= HARD_REGNO_NREGS (regno_first
, GET_MODE (reg
)) - 1;
3444 /* Find out if any of this register is live after this instruction. */
3445 some_was_live
= some_was_dead
= 0;
3446 for (i
= regno_first
; i
<= regno_last
; ++i
)
3448 int needed_regno
= REGNO_REG_SET_P (pbi
->reg_live
, i
);
3449 some_was_live
|= needed_regno
;
3450 some_was_dead
|= ! needed_regno
;
3453 /* Find out if any of the register was set this insn. */
3455 for (i
= regno_first
; i
<= regno_last
; ++i
)
3456 some_not_set
|= ! REGNO_REG_SET_P (pbi
->new_set
, i
);
3458 if (pbi
->flags
& (PROP_LOG_LINKS
| PROP_AUTOINC
))
3460 /* Record where each reg is used, so when the reg is set we know
3461 the next insn that uses it. */
3462 pbi
->reg_next_use
[regno_first
] = insn
;
3465 if (pbi
->flags
& PROP_REG_INFO
)
3467 if (regno_first
< FIRST_PSEUDO_REGISTER
)
3469 /* If this is a register we are going to try to eliminate,
3470 don't mark it live here. If we are successful in
3471 eliminating it, it need not be live unless it is used for
3472 pseudos, in which case it will have been set live when it
3473 was allocated to the pseudos. If the register will not
3474 be eliminated, reload will set it live at that point.
3476 Otherwise, record that this function uses this register. */
3477 /* ??? The PPC backend tries to "eliminate" on the pic
3478 register to itself. This should be fixed. In the mean
3479 time, hack around it. */
3481 if (! (TEST_HARD_REG_BIT (elim_reg_set
, regno_first
)
3482 && (regno_first
== FRAME_POINTER_REGNUM
3483 || regno_first
== ARG_POINTER_REGNUM
)))
3484 for (i
= regno_first
; i
<= regno_last
; ++i
)
3485 regs_ever_live
[i
] = 1;
3489 /* Keep track of which basic block each reg appears in. */
3491 int blocknum
= pbi
->bb
->index
;
3492 if (REG_BASIC_BLOCK (regno_first
) == REG_BLOCK_UNKNOWN
)
3493 REG_BASIC_BLOCK (regno_first
) = blocknum
;
3494 else if (REG_BASIC_BLOCK (regno_first
) != blocknum
)
3495 REG_BASIC_BLOCK (regno_first
) = REG_BLOCK_GLOBAL
;
3497 /* Count (weighted) number of uses of each reg. */
3498 REG_FREQ (regno_first
) += REG_FREQ_FROM_BB (pbi
->bb
);
3499 REG_N_REFS (regno_first
)++;
3503 /* Record and count the insns in which a reg dies. If it is used in
3504 this insn and was dead below the insn then it dies in this insn.
3505 If it was set in this insn, we do not make a REG_DEAD note;
3506 likewise if we already made such a note. */
3507 if ((pbi
->flags
& (PROP_DEATH_NOTES
| PROP_REG_INFO
))
3511 /* Check for the case where the register dying partially
3512 overlaps the register set by this insn. */
3513 if (regno_first
!= regno_last
)
3514 for (i
= regno_first
; i
<= regno_last
; ++i
)
3515 some_was_live
|= REGNO_REG_SET_P (pbi
->new_set
, i
);
3517 /* If none of the words in X is needed, make a REG_DEAD note.
3518 Otherwise, we must make partial REG_DEAD notes. */
3519 if (! some_was_live
)
3521 if ((pbi
->flags
& PROP_DEATH_NOTES
)
3522 && ! find_regno_note (insn
, REG_DEAD
, regno_first
))
3524 = alloc_EXPR_LIST (REG_DEAD
, reg
, REG_NOTES (insn
));
3526 if (pbi
->flags
& PROP_REG_INFO
)
3527 REG_N_DEATHS (regno_first
)++;
3531 /* Don't make a REG_DEAD note for a part of a register
3532 that is set in the insn. */
3533 for (i
= regno_first
; i
<= regno_last
; ++i
)
3534 if (! REGNO_REG_SET_P (pbi
->reg_live
, i
)
3535 && ! dead_or_set_regno_p (insn
, i
))
3537 = alloc_EXPR_LIST (REG_DEAD
,
3538 gen_rtx_REG (reg_raw_mode
[i
], i
),
3543 /* Mark the register as being live. */
3544 for (i
= regno_first
; i
<= regno_last
; ++i
)
3546 SET_REGNO_REG_SET (pbi
->reg_live
, i
);
3548 #ifdef HAVE_conditional_execution
3549 /* If this is a conditional use, record that fact. If it is later
3550 conditionally set, we'll know to kill the register. */
3551 if (cond
!= NULL_RTX
)
3553 splay_tree_node node
;
3554 struct reg_cond_life_info
*rcli
;
3559 node
= splay_tree_lookup (pbi
->reg_cond_dead
, i
);
3562 /* The register was unconditionally live previously.
3563 No need to do anything. */
3567 /* The register was conditionally live previously.
3568 Subtract the new life cond from the old death cond. */
3569 rcli
= (struct reg_cond_life_info
*) node
->value
;
3570 ncond
= rcli
->condition
;
3571 ncond
= and_reg_cond (ncond
, not_reg_cond (cond
), 1);
3573 /* If the register is now unconditionally live,
3574 remove the entry in the splay_tree. */
3575 if (ncond
== const0_rtx
)
3576 splay_tree_remove (pbi
->reg_cond_dead
, i
);
3579 rcli
->condition
= ncond
;
3580 SET_REGNO_REG_SET (pbi
->reg_cond_reg
,
3581 REGNO (XEXP (cond
, 0)));
3587 /* The register was not previously live at all. Record
3588 the condition under which it is still dead. */
3589 rcli
= (struct reg_cond_life_info
*) xmalloc (sizeof (*rcli
));
3590 rcli
->condition
= not_reg_cond (cond
);
3591 rcli
->stores
= const0_rtx
;
3592 rcli
->orig_condition
= const0_rtx
;
3593 splay_tree_insert (pbi
->reg_cond_dead
, i
,
3594 (splay_tree_value
) rcli
);
3596 SET_REGNO_REG_SET (pbi
->reg_cond_reg
, REGNO (XEXP (cond
, 0)));
3599 else if (some_was_live
)
3601 /* The register may have been conditionally live previously, but
3602 is now unconditionally live. Remove it from the conditionally
3603 dead list, so that a conditional set won't cause us to think
3605 splay_tree_remove (pbi
->reg_cond_dead
, i
);
3611 /* Scan expression X and store a 1-bit in NEW_LIVE for each reg it uses.
3612 This is done assuming the registers needed from X are those that
3613 have 1-bits in PBI->REG_LIVE.
3615 INSN is the containing instruction. If INSN is dead, this function
3619 mark_used_regs (pbi
, x
, cond
, insn
)
3620 struct propagate_block_info
*pbi
;
3625 int flags
= pbi
->flags
;
3630 code
= GET_CODE (x
);
3651 /* If we are clobbering a MEM, mark any registers inside the address
3653 if (GET_CODE (XEXP (x
, 0)) == MEM
)
3654 mark_used_regs (pbi
, XEXP (XEXP (x
, 0), 0), cond
, insn
);
3658 /* Don't bother watching stores to mems if this is not the
3659 final pass. We'll not be deleting dead stores this round. */
3660 if (optimize
&& (flags
& PROP_SCAN_DEAD_CODE
))
3662 /* Invalidate the data for the last MEM stored, but only if MEM is
3663 something that can be stored into. */
3664 if (GET_CODE (XEXP (x
, 0)) == SYMBOL_REF
3665 && CONSTANT_POOL_ADDRESS_P (XEXP (x
, 0)))
3666 /* Needn't clear the memory set list. */
3670 rtx temp
= pbi
->mem_set_list
;
3671 rtx prev
= NULL_RTX
;
3676 next
= XEXP (temp
, 1);
3677 if (anti_dependence (XEXP (temp
, 0), x
))
3679 /* Splice temp out of the list. */
3681 XEXP (prev
, 1) = next
;
3683 pbi
->mem_set_list
= next
;
3684 free_EXPR_LIST_node (temp
);
3685 pbi
->mem_set_list_len
--;
3693 /* If the memory reference had embedded side effects (autoincrement
3694 address modes. Then we may need to kill some entries on the
3697 invalidate_mems_from_autoinc (pbi
, insn
);
3701 if (flags
& PROP_AUTOINC
)
3702 find_auto_inc (pbi
, x
, insn
);
3707 #ifdef CLASS_CANNOT_CHANGE_MODE
3708 if (GET_CODE (SUBREG_REG (x
)) == REG
3709 && REGNO (SUBREG_REG (x
)) >= FIRST_PSEUDO_REGISTER
3710 && CLASS_CANNOT_CHANGE_MODE_P (GET_MODE (x
),
3711 GET_MODE (SUBREG_REG (x
))))
3712 REG_CHANGES_MODE (REGNO (SUBREG_REG (x
))) = 1;
3715 /* While we're here, optimize this case. */
3717 if (GET_CODE (x
) != REG
)
3722 /* See a register other than being set => mark it as needed. */
3723 mark_used_reg (pbi
, x
, cond
, insn
);
3728 rtx testreg
= SET_DEST (x
);
3731 /* If storing into MEM, don't show it as being used. But do
3732 show the address as being used. */
3733 if (GET_CODE (testreg
) == MEM
)
3736 if (flags
& PROP_AUTOINC
)
3737 find_auto_inc (pbi
, testreg
, insn
);
3739 mark_used_regs (pbi
, XEXP (testreg
, 0), cond
, insn
);
3740 mark_used_regs (pbi
, SET_SRC (x
), cond
, insn
);
3744 /* Storing in STRICT_LOW_PART is like storing in a reg
3745 in that this SET might be dead, so ignore it in TESTREG.
3746 but in some other ways it is like using the reg.
3748 Storing in a SUBREG or a bit field is like storing the entire
3749 register in that if the register's value is not used
3750 then this SET is not needed. */
3751 while (GET_CODE (testreg
) == STRICT_LOW_PART
3752 || GET_CODE (testreg
) == ZERO_EXTRACT
3753 || GET_CODE (testreg
) == SIGN_EXTRACT
3754 || GET_CODE (testreg
) == SUBREG
)
3756 #ifdef CLASS_CANNOT_CHANGE_MODE
3757 if (GET_CODE (testreg
) == SUBREG
3758 && GET_CODE (SUBREG_REG (testreg
)) == REG
3759 && REGNO (SUBREG_REG (testreg
)) >= FIRST_PSEUDO_REGISTER
3760 && CLASS_CANNOT_CHANGE_MODE_P (GET_MODE (SUBREG_REG (testreg
)),
3761 GET_MODE (testreg
)))
3762 REG_CHANGES_MODE (REGNO (SUBREG_REG (testreg
))) = 1;
3765 /* Modifying a single register in an alternate mode
3766 does not use any of the old value. But these other
3767 ways of storing in a register do use the old value. */
3768 if (GET_CODE (testreg
) == SUBREG
3769 && !((REG_BYTES (SUBREG_REG (testreg
))
3770 + UNITS_PER_WORD
- 1) / UNITS_PER_WORD
3771 > (REG_BYTES (testreg
)
3772 + UNITS_PER_WORD
- 1) / UNITS_PER_WORD
))
3777 testreg
= XEXP (testreg
, 0);
3780 /* If this is a store into a register or group of registers,
3781 recursively scan the value being stored. */
3783 if ((GET_CODE (testreg
) == PARALLEL
3784 && GET_MODE (testreg
) == BLKmode
)
3785 || (GET_CODE (testreg
) == REG
3786 && (regno
= REGNO (testreg
),
3787 ! (regno
== FRAME_POINTER_REGNUM
3788 && (! reload_completed
|| frame_pointer_needed
)))
3789 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
3790 && ! (regno
== HARD_FRAME_POINTER_REGNUM
3791 && (! reload_completed
|| frame_pointer_needed
))
3793 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
3794 && ! (regno
== ARG_POINTER_REGNUM
&& fixed_regs
[regno
])
3799 mark_used_regs (pbi
, SET_DEST (x
), cond
, insn
);
3800 mark_used_regs (pbi
, SET_SRC (x
), cond
, insn
);
3807 case UNSPEC_VOLATILE
:
3811 /* Traditional and volatile asm instructions must be considered to use
3812 and clobber all hard registers, all pseudo-registers and all of
3813 memory. So must TRAP_IF and UNSPEC_VOLATILE operations.
3815 Consider for instance a volatile asm that changes the fpu rounding
3816 mode. An insn should not be moved across this even if it only uses
3817 pseudo-regs because it might give an incorrectly rounded result.
3819 ?!? Unfortunately, marking all hard registers as live causes massive
3820 problems for the register allocator and marking all pseudos as live
3821 creates mountains of uninitialized variable warnings.
3823 So for now, just clear the memory set list and mark any regs
3824 we can find in ASM_OPERANDS as used. */
3825 if (code
!= ASM_OPERANDS
|| MEM_VOLATILE_P (x
))
3827 free_EXPR_LIST_list (&pbi
->mem_set_list
);
3828 pbi
->mem_set_list_len
= 0;
3831 /* For all ASM_OPERANDS, we must traverse the vector of input operands.
3832 We can not just fall through here since then we would be confused
3833 by the ASM_INPUT rtx inside ASM_OPERANDS, which do not indicate
3834 traditional asms unlike their normal usage. */
3835 if (code
== ASM_OPERANDS
)
3839 for (j
= 0; j
< ASM_OPERANDS_INPUT_LENGTH (x
); j
++)
3840 mark_used_regs (pbi
, ASM_OPERANDS_INPUT (x
, j
), cond
, insn
);
3846 if (cond
!= NULL_RTX
)
3849 mark_used_regs (pbi
, COND_EXEC_TEST (x
), NULL_RTX
, insn
);
3851 cond
= COND_EXEC_TEST (x
);
3852 x
= COND_EXEC_CODE (x
);
3856 /* We _do_not_ want to scan operands of phi nodes. Operands of
3857 a phi function are evaluated only when control reaches this
3858 block along a particular edge. Therefore, regs that appear
3859 as arguments to phi should not be added to the global live at
3867 /* Recursively scan the operands of this expression. */
3870 const char * const fmt
= GET_RTX_FORMAT (code
);
3873 for (i
= GET_RTX_LENGTH (code
) - 1; i
>= 0; i
--)
3877 /* Tail recursive case: save a function call level. */
3883 mark_used_regs (pbi
, XEXP (x
, i
), cond
, insn
);
3885 else if (fmt
[i
] == 'E')
3888 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
3889 mark_used_regs (pbi
, XVECEXP (x
, i
, j
), cond
, insn
);
3898 try_pre_increment_1 (pbi
, insn
)
3899 struct propagate_block_info
*pbi
;
3902 /* Find the next use of this reg. If in same basic block,
3903 make it do pre-increment or pre-decrement if appropriate. */
3904 rtx x
= single_set (insn
);
3905 HOST_WIDE_INT amount
= ((GET_CODE (SET_SRC (x
)) == PLUS
? 1 : -1)
3906 * INTVAL (XEXP (SET_SRC (x
), 1)));
3907 int regno
= REGNO (SET_DEST (x
));
3908 rtx y
= pbi
->reg_next_use
[regno
];
3910 && SET_DEST (x
) != stack_pointer_rtx
3911 && BLOCK_NUM (y
) == BLOCK_NUM (insn
)
3912 /* Don't do this if the reg dies, or gets set in y; a standard addressing
3913 mode would be better. */
3914 && ! dead_or_set_p (y
, SET_DEST (x
))
3915 && try_pre_increment (y
, SET_DEST (x
), amount
))
3917 /* We have found a suitable auto-increment and already changed
3918 insn Y to do it. So flush this increment instruction. */
3919 propagate_block_delete_insn (pbi
->bb
, insn
);
3921 /* Count a reference to this reg for the increment insn we are
3922 deleting. When a reg is incremented, spilling it is worse,
3923 so we want to make that less likely. */
3924 if (regno
>= FIRST_PSEUDO_REGISTER
)
3926 REG_FREQ (regno
) += REG_FREQ_FROM_BB (pbi
->bb
);
3927 REG_N_SETS (regno
)++;
3930 /* Flush any remembered memories depending on the value of
3931 the incremented register. */
3932 invalidate_mems_from_set (pbi
, SET_DEST (x
));
3939 /* Try to change INSN so that it does pre-increment or pre-decrement
3940 addressing on register REG in order to add AMOUNT to REG.
3941 AMOUNT is negative for pre-decrement.
3942 Returns 1 if the change could be made.
3943 This checks all about the validity of the result of modifying INSN. */
3946 try_pre_increment (insn
, reg
, amount
)
3948 HOST_WIDE_INT amount
;
3952 /* Nonzero if we can try to make a pre-increment or pre-decrement.
3953 For example, addl $4,r1; movl (r1),... can become movl +(r1),... */
3955 /* Nonzero if we can try to make a post-increment or post-decrement.
3956 For example, addl $4,r1; movl -4(r1),... can become movl (r1)+,...
3957 It is possible for both PRE_OK and POST_OK to be nonzero if the machine
3958 supports both pre-inc and post-inc, or both pre-dec and post-dec. */
3961 /* Nonzero if the opportunity actually requires post-inc or post-dec. */
3964 /* From the sign of increment, see which possibilities are conceivable
3965 on this target machine. */
3966 if (HAVE_PRE_INCREMENT
&& amount
> 0)
3968 if (HAVE_POST_INCREMENT
&& amount
> 0)
3971 if (HAVE_PRE_DECREMENT
&& amount
< 0)
3973 if (HAVE_POST_DECREMENT
&& amount
< 0)
3976 if (! (pre_ok
|| post_ok
))
3979 /* It is not safe to add a side effect to a jump insn
3980 because if the incremented register is spilled and must be reloaded
3981 there would be no way to store the incremented value back in memory. */
3983 if (GET_CODE (insn
) == JUMP_INSN
)
3988 use
= find_use_as_address (PATTERN (insn
), reg
, 0);
3989 if (post_ok
&& (use
== 0 || use
== (rtx
) (size_t) 1))
3991 use
= find_use_as_address (PATTERN (insn
), reg
, -amount
);
3995 if (use
== 0 || use
== (rtx
) (size_t) 1)
3998 if (GET_MODE_SIZE (GET_MODE (use
)) != (amount
> 0 ? amount
: - amount
))
4001 /* See if this combination of instruction and addressing mode exists. */
4002 if (! validate_change (insn
, &XEXP (use
, 0),
4003 gen_rtx_fmt_e (amount
> 0
4004 ? (do_post
? POST_INC
: PRE_INC
)
4005 : (do_post
? POST_DEC
: PRE_DEC
),
4009 /* Record that this insn now has an implicit side effect on X. */
4010 REG_NOTES (insn
) = alloc_EXPR_LIST (REG_INC
, reg
, REG_NOTES (insn
));
4014 #endif /* AUTO_INC_DEC */
4016 /* Find the place in the rtx X where REG is used as a memory address.
4017 Return the MEM rtx that so uses it.
4018 If PLUSCONST is nonzero, search instead for a memory address equivalent to
4019 (plus REG (const_int PLUSCONST)).
4021 If such an address does not appear, return 0.
4022 If REG appears more than once, or is used other than in such an address,
4026 find_use_as_address (x
, reg
, plusconst
)
4029 HOST_WIDE_INT plusconst
;
4031 enum rtx_code code
= GET_CODE (x
);
4032 const char * const fmt
= GET_RTX_FORMAT (code
);
4037 if (code
== MEM
&& XEXP (x
, 0) == reg
&& plusconst
== 0)
4040 if (code
== MEM
&& GET_CODE (XEXP (x
, 0)) == PLUS
4041 && XEXP (XEXP (x
, 0), 0) == reg
4042 && GET_CODE (XEXP (XEXP (x
, 0), 1)) == CONST_INT
4043 && INTVAL (XEXP (XEXP (x
, 0), 1)) == plusconst
)
4046 if (code
== SIGN_EXTRACT
|| code
== ZERO_EXTRACT
)
4048 /* If REG occurs inside a MEM used in a bit-field reference,
4049 that is unacceptable. */
4050 if (find_use_as_address (XEXP (x
, 0), reg
, 0) != 0)
4051 return (rtx
) (size_t) 1;
4055 return (rtx
) (size_t) 1;
4057 for (i
= GET_RTX_LENGTH (code
) - 1; i
>= 0; i
--)
4061 tem
= find_use_as_address (XEXP (x
, i
), reg
, plusconst
);
4065 return (rtx
) (size_t) 1;
4067 else if (fmt
[i
] == 'E')
4070 for (j
= XVECLEN (x
, i
) - 1; j
>= 0; j
--)
4072 tem
= find_use_as_address (XVECEXP (x
, i
, j
), reg
, plusconst
);
4076 return (rtx
) (size_t) 1;
4084 /* Write information about registers and basic blocks into FILE.
4085 This is part of making a debugging dump. */
4088 dump_regset (r
, outf
)
4095 fputs (" (nil)", outf
);
4099 EXECUTE_IF_SET_IN_REG_SET (r
, 0, i
,
4101 fprintf (outf
, " %d", i
);
4102 if (i
< FIRST_PSEUDO_REGISTER
)
4103 fprintf (outf
, " [%s]",
4108 /* Print a human-reaable representation of R on the standard error
4109 stream. This function is designed to be used from within the
4116 dump_regset (r
, stderr
);
4117 putc ('\n', stderr
);
4120 /* Recompute register set/reference counts immediately prior to register
4123 This avoids problems with set/reference counts changing to/from values
4124 which have special meanings to the register allocators.
4126 Additionally, the reference counts are the primary component used by the
4127 register allocators to prioritize pseudos for allocation to hard regs.
4128 More accurate reference counts generally lead to better register allocation.
4130 F is the first insn to be scanned.
4132 LOOP_STEP denotes how much loop_depth should be incremented per
4133 loop nesting level in order to increase the ref count more for
4134 references in a loop.
4136 It might be worthwhile to update REG_LIVE_LENGTH, REG_BASIC_BLOCK and
4137 possibly other information which is used by the register allocators. */
4140 recompute_reg_usage (f
, loop_step
)
4141 rtx f ATTRIBUTE_UNUSED
;
4142 int loop_step ATTRIBUTE_UNUSED
;
4144 allocate_reg_life_data ();
4145 update_life_info (NULL
, UPDATE_LIFE_LOCAL
, PROP_REG_INFO
);
4148 /* Optionally removes all the REG_DEAD and REG_UNUSED notes from a set of
4149 blocks. If BLOCKS is NULL, assume the universal set. Returns a count
4150 of the number of registers that died. */
4153 count_or_remove_death_notes (blocks
, kill
)
4159 for (i
= n_basic_blocks
- 1; i
>= 0; --i
)
4164 if (blocks
&& ! TEST_BIT (blocks
, i
))
4167 bb
= BASIC_BLOCK (i
);
4169 for (insn
= bb
->head
;; insn
= NEXT_INSN (insn
))
4173 rtx
*pprev
= ®_NOTES (insn
);
4178 switch (REG_NOTE_KIND (link
))
4181 if (GET_CODE (XEXP (link
, 0)) == REG
)
4183 rtx reg
= XEXP (link
, 0);
4186 if (REGNO (reg
) >= FIRST_PSEUDO_REGISTER
)
4189 n
= HARD_REGNO_NREGS (REGNO (reg
), GET_MODE (reg
));
4197 rtx next
= XEXP (link
, 1);
4198 free_EXPR_LIST_node (link
);
4199 *pprev
= link
= next
;
4205 pprev
= &XEXP (link
, 1);
4212 if (insn
== bb
->end
)
4219 /* Clear LOG_LINKS fields of insns in a selected blocks or whole chain
4220 if blocks is NULL. */
4223 clear_log_links (blocks
)
4231 for (insn
= get_insns (); insn
; insn
= NEXT_INSN (insn
))
4233 free_INSN_LIST_list (&LOG_LINKS (insn
));
4236 EXECUTE_IF_SET_IN_SBITMAP (blocks
, 0, i
,
4238 basic_block bb
= BASIC_BLOCK (i
);
4240 for (insn
= bb
->head
; insn
!= NEXT_INSN (bb
->end
);
4241 insn
= NEXT_INSN (insn
))
4243 free_INSN_LIST_list (&LOG_LINKS (insn
));
4247 /* Given a register bitmap, turn on the bits in a HARD_REG_SET that
4248 correspond to the hard registers, if any, set in that map. This
4249 could be done far more efficiently by having all sorts of special-cases
4250 with moving single words, but probably isn't worth the trouble. */
4253 reg_set_to_hard_reg_set (to
, from
)
4259 EXECUTE_IF_SET_IN_BITMAP
4262 if (i
>= FIRST_PSEUDO_REGISTER
)
4264 SET_HARD_REG_BIT (*to
, i
);