1 /* Data flow analysis for GNU compiler.
2 Copyright (C) 1987, 1988, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
3 1999, 2000, 2001, 2002, 2003, 2004 Free Software Foundation, Inc.
5 This file is part of GCC.
7 GCC is free software; you can redistribute it and/or modify it under
8 the terms of the GNU General Public License as published by the Free
9 Software Foundation; either version 2, or (at your option) any later
12 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
13 WARRANTY; without even the implied warranty of MERCHANTABILITY or
14 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
17 You should have received a copy of the GNU General Public License
18 along with GCC; see the file COPYING. If not, write to the Free
19 Software Foundation, 59 Temple Place - Suite 330, Boston, MA
22 /* This file contains the data flow analysis pass of the compiler. It
23 computes data flow information which tells combine_instructions
24 which insns to consider combining and controls register allocation.
26 Additional data flow information that is too bulky to record is
27 generated during the analysis, and is used at that time to create
28 autoincrement and autodecrement addressing.
30 The first step is dividing the function into basic blocks.
31 find_basic_blocks does this. Then life_analysis determines
32 where each register is live and where it is dead.
34 ** find_basic_blocks **
36 find_basic_blocks divides the current function's rtl into basic
37 blocks and constructs the CFG. The blocks are recorded in the
38 basic_block_info array; the CFG exists in the edge structures
39 referenced by the blocks.
41 find_basic_blocks also finds any unreachable loops and deletes them.
45 life_analysis is called immediately after find_basic_blocks.
46 It uses the basic block information to determine where each
47 hard or pseudo register is live.
49 ** live-register info **
51 The information about where each register is live is in two parts:
52 the REG_NOTES of insns, and the vector basic_block->global_live_at_start.
54 basic_block->global_live_at_start has an element for each basic
55 block, and the element is a bit-vector with a bit for each hard or
56 pseudo register. The bit is 1 if the register is live at the
57 beginning of the basic block.
59 Two types of elements can be added to an insn's REG_NOTES.
60 A REG_DEAD note is added to an insn's REG_NOTES for any register
61 that meets both of two conditions: The value in the register is not
62 needed in subsequent insns and the insn does not replace the value in
63 the register (in the case of multi-word hard registers, the value in
64 each register must be replaced by the insn to avoid a REG_DEAD note).
66 In the vast majority of cases, an object in a REG_DEAD note will be
67 used somewhere in the insn. The (rare) exception to this is if an
68 insn uses a multi-word hard register and only some of the registers are
69 needed in subsequent insns. In that case, REG_DEAD notes will be
70 provided for those hard registers that are not subsequently needed.
71 Partial REG_DEAD notes of this type do not occur when an insn sets
72 only some of the hard registers used in such a multi-word operand;
73 omitting REG_DEAD notes for objects stored in an insn is optional and
74 the desire to do so does not justify the complexity of the partial
77 REG_UNUSED notes are added for each register that is set by the insn
78 but is unused subsequently (if every register set by the insn is unused
79 and the insn does not reference memory or have some other side-effect,
80 the insn is deleted instead). If only part of a multi-word hard
81 register is used in a subsequent insn, REG_UNUSED notes are made for
82 the parts that will not be used.
84 To determine which registers are live after any insn, one can
85 start from the beginning of the basic block and scan insns, noting
86 which registers are set by each insn and which die there.
88 ** Other actions of life_analysis **
90 life_analysis sets up the LOG_LINKS fields of insns because the
91 information needed to do so is readily available.
93 life_analysis deletes insns whose only effect is to store a value
96 life_analysis notices cases where a reference to a register as
97 a memory address can be combined with a preceding or following
98 incrementation or decrementation of the register. The separate
99 instruction to increment or decrement is deleted and the address
100 is changed to a POST_INC or similar rtx.
102 Each time an incrementing or decrementing address is created,
103 a REG_INC element is added to the insn's REG_NOTES list.
105 life_analysis fills in certain vectors containing information about
106 register usage: REG_N_REFS, REG_N_DEATHS, REG_N_SETS, REG_LIVE_LENGTH,
107 REG_N_CALLS_CROSSED and REG_BASIC_BLOCK.
109 life_analysis sets current_function_sp_is_unchanging if the function
110 doesn't modify the stack pointer. */
114 Split out from life_analysis:
115 - local property discovery (bb->local_live, bb->local_set)
116 - global property computation
118 - pre/post modify transformation
123 #include "coretypes.h"
128 #include "hard-reg-set.h"
129 #include "basic-block.h"
130 #include "insn-config.h"
134 #include "function.h"
142 #include "splay-tree.h"
144 #ifndef HAVE_epilogue
145 #define HAVE_epilogue 0
147 #ifndef HAVE_prologue
148 #define HAVE_prologue 0
150 #ifndef HAVE_sibcall_epilogue
151 #define HAVE_sibcall_epilogue 0
154 #ifndef EPILOGUE_USES
155 #define EPILOGUE_USES(REGNO) 0
158 #define EH_USES(REGNO) 0
161 #ifdef HAVE_conditional_execution
162 #ifndef REVERSE_CONDEXEC_PREDICATES_P
163 #define REVERSE_CONDEXEC_PREDICATES_P(x, y) ((x) == reverse_condition (y))
167 /* Nonzero if the second flow pass has completed. */
170 /* Maximum register number used in this function, plus one. */
174 /* Indexed by n, giving various register information */
176 varray_type reg_n_info
;
178 /* Size of a regset for the current function,
179 in (1) bytes and (2) elements. */
184 /* Regset of regs live when calls to `setjmp'-like functions happen. */
185 /* ??? Does this exist only for the setjmp-clobbered warning message? */
187 regset regs_live_at_setjmp
;
189 /* List made of EXPR_LIST rtx's which gives pairs of pseudo registers
190 that have to go in the same hard reg.
191 The first two regs in the list are a pair, and the next two
192 are another pair, etc. */
195 /* Set of registers that may be eliminable. These are handled specially
196 in updating regs_ever_live. */
198 static HARD_REG_SET elim_reg_set
;
200 /* Holds information for tracking conditional register life information. */
201 struct reg_cond_life_info
203 /* A boolean expression of conditions under which a register is dead. */
205 /* Conditions under which a register is dead at the basic block end. */
208 /* A boolean expression of conditions under which a register has been
212 /* ??? Could store mask of bytes that are dead, so that we could finally
213 track lifetimes of multi-word registers accessed via subregs. */
216 /* For use in communicating between propagate_block and its subroutines.
217 Holds all information needed to compute life and def-use information. */
219 struct propagate_block_info
221 /* The basic block we're considering. */
224 /* Bit N is set if register N is conditionally or unconditionally live. */
227 /* Bit N is set if register N is set this insn. */
230 /* Element N is the next insn that uses (hard or pseudo) register N
231 within the current basic block; or zero, if there is no such insn. */
234 /* Contains a list of all the MEMs we are tracking for dead store
238 /* If non-null, record the set of registers set unconditionally in the
242 /* If non-null, record the set of registers set conditionally in the
244 regset cond_local_set
;
246 #ifdef HAVE_conditional_execution
247 /* Indexed by register number, holds a reg_cond_life_info for each
248 register that is not unconditionally live or dead. */
249 splay_tree reg_cond_dead
;
251 /* Bit N is set if register N is in an expression in reg_cond_dead. */
255 /* The length of mem_set_list. */
256 int mem_set_list_len
;
258 /* Nonzero if the value of CC0 is live. */
261 /* Flags controlling the set of information propagate_block collects. */
263 /* Index of instruction being processed. */
267 /* Number of dead insns removed. */
270 /* When PROP_REG_INFO set, array contains pbi->insn_num of instruction
271 where given register died. When the register is marked alive, we use the
272 information to compute amount of instructions life range cross.
273 (remember, we are walking backward). This can be computed as current
274 pbi->insn_num - reg_deaths[regno].
275 At the end of processing each basic block, the remaining live registers
276 are inspected and liferanges are increased same way so liverange of global
277 registers are computed correctly.
279 The array is maintained clear for dead registers, so it can be safely reused
280 for next basic block without expensive memset of the whole array after
281 reseting pbi->insn_num to 0. */
283 static int *reg_deaths
;
285 /* Maximum length of pbi->mem_set_list before we start dropping
286 new elements on the floor. */
287 #define MAX_MEM_SET_LIST_LEN 100
289 /* Forward declarations */
290 static int verify_wide_reg_1 (rtx
*, void *);
291 static void verify_wide_reg (int, basic_block
);
292 static void verify_local_live_at_start (regset
, basic_block
);
293 static void notice_stack_pointer_modification_1 (rtx
, rtx
, void *);
294 static void notice_stack_pointer_modification (void);
295 static void mark_reg (rtx
, void *);
296 static void mark_regs_live_at_end (regset
);
297 static void calculate_global_regs_live (sbitmap
, sbitmap
, int);
298 static void propagate_block_delete_insn (rtx
);
299 static rtx
propagate_block_delete_libcall (rtx
, rtx
);
300 static int insn_dead_p (struct propagate_block_info
*, rtx
, int, rtx
);
301 static int libcall_dead_p (struct propagate_block_info
*, rtx
, rtx
);
302 static void mark_set_regs (struct propagate_block_info
*, rtx
, rtx
);
303 static void mark_set_1 (struct propagate_block_info
*, enum rtx_code
, rtx
,
305 static int find_regno_partial (rtx
*, void *);
307 #ifdef HAVE_conditional_execution
308 static int mark_regno_cond_dead (struct propagate_block_info
*, int, rtx
);
309 static void free_reg_cond_life_info (splay_tree_value
);
310 static int flush_reg_cond_reg_1 (splay_tree_node
, void *);
311 static void flush_reg_cond_reg (struct propagate_block_info
*, int);
312 static rtx
elim_reg_cond (rtx
, unsigned int);
313 static rtx
ior_reg_cond (rtx
, rtx
, int);
314 static rtx
not_reg_cond (rtx
);
315 static rtx
and_reg_cond (rtx
, rtx
, int);
318 static void attempt_auto_inc (struct propagate_block_info
*, rtx
, rtx
, rtx
,
320 static void find_auto_inc (struct propagate_block_info
*, rtx
, rtx
);
321 static int try_pre_increment_1 (struct propagate_block_info
*, rtx
);
322 static int try_pre_increment (rtx
, rtx
, HOST_WIDE_INT
);
324 static void mark_used_reg (struct propagate_block_info
*, rtx
, rtx
, rtx
);
325 static void mark_used_regs (struct propagate_block_info
*, rtx
, rtx
, rtx
);
326 void debug_flow_info (void);
327 static void add_to_mem_set_list (struct propagate_block_info
*, rtx
);
328 static int invalidate_mems_from_autoinc (rtx
*, void *);
329 static void invalidate_mems_from_set (struct propagate_block_info
*, rtx
);
330 static void clear_log_links (sbitmap
);
331 static int count_or_remove_death_notes_bb (basic_block
, int);
333 /* Return the INSN immediately following the NOTE_INSN_BASIC_BLOCK
334 note associated with the BLOCK. */
337 first_insn_after_basic_block_note (basic_block block
)
341 /* Get the first instruction in the block. */
342 insn
= BB_HEAD (block
);
344 if (insn
== NULL_RTX
)
346 if (GET_CODE (insn
) == CODE_LABEL
)
347 insn
= NEXT_INSN (insn
);
348 if (!NOTE_INSN_BASIC_BLOCK_P (insn
))
351 return NEXT_INSN (insn
);
354 /* Perform data flow analysis for the whole control flow graph.
355 FLAGS is a set of PROP_* flags to be used in accumulating flow info. */
358 life_analysis (FILE *file
, int flags
)
360 #ifdef ELIMINABLE_REGS
362 static const struct {const int from
, to
; } eliminables
[] = ELIMINABLE_REGS
;
365 /* Record which registers will be eliminated. We use this in
368 CLEAR_HARD_REG_SET (elim_reg_set
);
370 #ifdef ELIMINABLE_REGS
371 for (i
= 0; i
< (int) ARRAY_SIZE (eliminables
); i
++)
372 SET_HARD_REG_BIT (elim_reg_set
, eliminables
[i
].from
);
374 SET_HARD_REG_BIT (elim_reg_set
, FRAME_POINTER_REGNUM
);
378 #ifdef CANNOT_CHANGE_MODE_CLASS
379 if (flags
& PROP_REG_INFO
)
380 bitmap_initialize (&subregs_of_mode
, 1);
384 flags
&= ~(PROP_LOG_LINKS
| PROP_AUTOINC
| PROP_ALLOW_CFG_CHANGES
);
386 /* The post-reload life analysis have (on a global basis) the same
387 registers live as was computed by reload itself. elimination
388 Otherwise offsets and such may be incorrect.
390 Reload will make some registers as live even though they do not
393 We don't want to create new auto-incs after reload, since they
394 are unlikely to be useful and can cause problems with shared
396 if (reload_completed
)
397 flags
&= ~(PROP_REG_INFO
| PROP_AUTOINC
);
399 /* We want alias analysis information for local dead store elimination. */
400 if (optimize
&& (flags
& PROP_SCAN_DEAD_STORES
))
401 init_alias_analysis ();
403 /* Always remove no-op moves. Do this before other processing so
404 that we don't have to keep re-scanning them. */
405 delete_noop_moves ();
407 /* Some targets can emit simpler epilogues if they know that sp was
408 not ever modified during the function. After reload, of course,
409 we've already emitted the epilogue so there's no sense searching. */
410 if (! reload_completed
)
411 notice_stack_pointer_modification ();
413 /* Allocate and zero out data structures that will record the
414 data from lifetime analysis. */
415 allocate_reg_life_data ();
416 allocate_bb_life_data ();
418 /* Find the set of registers live on function exit. */
419 mark_regs_live_at_end (EXIT_BLOCK_PTR
->global_live_at_start
);
421 /* "Update" life info from zero. It'd be nice to begin the
422 relaxation with just the exit and noreturn blocks, but that set
423 is not immediately handy. */
425 if (flags
& PROP_REG_INFO
)
427 memset (regs_ever_live
, 0, sizeof (regs_ever_live
));
428 memset (regs_asm_clobbered
, 0, sizeof (regs_asm_clobbered
));
430 update_life_info (NULL
, UPDATE_LIFE_GLOBAL
, flags
);
438 if (optimize
&& (flags
& PROP_SCAN_DEAD_STORES
))
439 end_alias_analysis ();
442 dump_flow_info (file
);
444 /* Removing dead insns should have made jumptables really dead. */
445 delete_dead_jumptables ();
448 /* A subroutine of verify_wide_reg, called through for_each_rtx.
449 Search for REGNO. If found, return 2 if it is not wider than
453 verify_wide_reg_1 (rtx
*px
, void *pregno
)
456 unsigned int regno
= *(int *) pregno
;
458 if (GET_CODE (x
) == REG
&& REGNO (x
) == regno
)
460 if (GET_MODE_BITSIZE (GET_MODE (x
)) <= BITS_PER_WORD
)
467 /* A subroutine of verify_local_live_at_start. Search through insns
468 of BB looking for register REGNO. */
471 verify_wide_reg (int regno
, basic_block bb
)
473 rtx head
= BB_HEAD (bb
), end
= BB_END (bb
);
479 int r
= for_each_rtx (&PATTERN (head
), verify_wide_reg_1
, ®no
);
487 head
= NEXT_INSN (head
);
492 fprintf (dump_file
, "Register %d died unexpectedly.\n", regno
);
493 dump_bb (bb
, dump_file
, 0);
498 /* A subroutine of update_life_info. Verify that there are no untoward
499 changes in live_at_start during a local update. */
502 verify_local_live_at_start (regset new_live_at_start
, basic_block bb
)
504 if (reload_completed
)
506 /* After reload, there are no pseudos, nor subregs of multi-word
507 registers. The regsets should exactly match. */
508 if (! REG_SET_EQUAL_P (new_live_at_start
, bb
->global_live_at_start
))
513 "live_at_start mismatch in bb %d, aborting\nNew:\n",
515 debug_bitmap_file (dump_file
, new_live_at_start
);
516 fputs ("Old:\n", dump_file
);
517 dump_bb (bb
, dump_file
, 0);
526 /* Find the set of changed registers. */
527 XOR_REG_SET (new_live_at_start
, bb
->global_live_at_start
);
529 EXECUTE_IF_SET_IN_REG_SET (new_live_at_start
, 0, i
,
531 /* No registers should die. */
532 if (REGNO_REG_SET_P (bb
->global_live_at_start
, i
))
537 "Register %d died unexpectedly.\n", i
);
538 dump_bb (bb
, dump_file
, 0);
543 /* Verify that the now-live register is wider than word_mode. */
544 verify_wide_reg (i
, bb
);
549 /* Updates life information starting with the basic blocks set in BLOCKS.
550 If BLOCKS is null, consider it to be the universal set.
552 If EXTENT is UPDATE_LIFE_LOCAL, such as after splitting or peepholing,
553 we are only expecting local modifications to basic blocks. If we find
554 extra registers live at the beginning of a block, then we either killed
555 useful data, or we have a broken split that wants data not provided.
556 If we find registers removed from live_at_start, that means we have
557 a broken peephole that is killing a register it shouldn't.
559 ??? This is not true in one situation -- when a pre-reload splitter
560 generates subregs of a multi-word pseudo, current life analysis will
561 lose the kill. So we _can_ have a pseudo go live. How irritating.
563 It is also not true when a peephole decides that it doesn't need one
564 or more of the inputs.
566 Including PROP_REG_INFO does not properly refresh regs_ever_live
567 unless the caller resets it to zero. */
570 update_life_info (sbitmap blocks
, enum update_life_extent extent
, int prop_flags
)
573 regset_head tmp_head
;
575 int stabilized_prop_flags
= prop_flags
;
578 tmp
= INITIALIZE_REG_SET (tmp_head
);
581 if ((prop_flags
& PROP_REG_INFO
) && !reg_deaths
)
582 reg_deaths
= xcalloc (sizeof (*reg_deaths
), max_regno
);
584 timevar_push ((extent
== UPDATE_LIFE_LOCAL
|| blocks
)
585 ? TV_LIFE_UPDATE
: TV_LIFE
);
587 /* Changes to the CFG are only allowed when
588 doing a global update for the entire CFG. */
589 if ((prop_flags
& PROP_ALLOW_CFG_CHANGES
)
590 && (extent
== UPDATE_LIFE_LOCAL
|| blocks
))
593 /* For a global update, we go through the relaxation process again. */
594 if (extent
!= UPDATE_LIFE_LOCAL
)
600 calculate_global_regs_live (blocks
, blocks
,
601 prop_flags
& (PROP_SCAN_DEAD_CODE
602 | PROP_SCAN_DEAD_STORES
603 | PROP_ALLOW_CFG_CHANGES
));
605 if ((prop_flags
& (PROP_KILL_DEAD_CODE
| PROP_ALLOW_CFG_CHANGES
))
606 != (PROP_KILL_DEAD_CODE
| PROP_ALLOW_CFG_CHANGES
))
609 /* Removing dead code may allow the CFG to be simplified which
610 in turn may allow for further dead code detection / removal. */
611 FOR_EACH_BB_REVERSE (bb
)
613 COPY_REG_SET (tmp
, bb
->global_live_at_end
);
614 changed
|= propagate_block (bb
, tmp
, NULL
, NULL
,
615 prop_flags
& (PROP_SCAN_DEAD_CODE
616 | PROP_SCAN_DEAD_STORES
617 | PROP_KILL_DEAD_CODE
));
620 /* Don't pass PROP_SCAN_DEAD_CODE or PROP_KILL_DEAD_CODE to
621 subsequent propagate_block calls, since removing or acting as
622 removing dead code can affect global register liveness, which
623 is supposed to be finalized for this call after this loop. */
624 stabilized_prop_flags
625 &= ~(PROP_SCAN_DEAD_CODE
| PROP_SCAN_DEAD_STORES
626 | PROP_KILL_DEAD_CODE
);
631 /* We repeat regardless of what cleanup_cfg says. If there were
632 instructions deleted above, that might have been only a
633 partial improvement (see MAX_MEM_SET_LIST_LEN usage).
634 Further improvement may be possible. */
635 cleanup_cfg (CLEANUP_EXPENSIVE
);
637 /* Zap the life information from the last round. If we don't
638 do this, we can wind up with registers that no longer appear
639 in the code being marked live at entry. */
642 CLEAR_REG_SET (bb
->global_live_at_start
);
643 CLEAR_REG_SET (bb
->global_live_at_end
);
647 /* If asked, remove notes from the blocks we'll update. */
648 if (extent
== UPDATE_LIFE_GLOBAL_RM_NOTES
)
649 count_or_remove_death_notes (blocks
, 1);
652 /* Clear log links in case we are asked to (re)compute them. */
653 if (prop_flags
& PROP_LOG_LINKS
)
654 clear_log_links (blocks
);
658 EXECUTE_IF_SET_IN_SBITMAP (blocks
, 0, i
,
660 bb
= BASIC_BLOCK (i
);
662 COPY_REG_SET (tmp
, bb
->global_live_at_end
);
663 propagate_block (bb
, tmp
, NULL
, NULL
, stabilized_prop_flags
);
665 if (extent
== UPDATE_LIFE_LOCAL
)
666 verify_local_live_at_start (tmp
, bb
);
671 FOR_EACH_BB_REVERSE (bb
)
673 COPY_REG_SET (tmp
, bb
->global_live_at_end
);
675 propagate_block (bb
, tmp
, NULL
, NULL
, stabilized_prop_flags
);
677 if (extent
== UPDATE_LIFE_LOCAL
)
678 verify_local_live_at_start (tmp
, bb
);
684 if (prop_flags
& PROP_REG_INFO
)
686 /* The only pseudos that are live at the beginning of the function
687 are those that were not set anywhere in the function. local-alloc
688 doesn't know how to handle these correctly, so mark them as not
689 local to any one basic block. */
690 EXECUTE_IF_SET_IN_REG_SET (ENTRY_BLOCK_PTR
->global_live_at_end
,
691 FIRST_PSEUDO_REGISTER
, i
,
692 { REG_BASIC_BLOCK (i
) = REG_BLOCK_GLOBAL
; });
694 /* We have a problem with any pseudoreg that lives across the setjmp.
695 ANSI says that if a user variable does not change in value between
696 the setjmp and the longjmp, then the longjmp preserves it. This
697 includes longjmp from a place where the pseudo appears dead.
698 (In principle, the value still exists if it is in scope.)
699 If the pseudo goes in a hard reg, some other value may occupy
700 that hard reg where this pseudo is dead, thus clobbering the pseudo.
701 Conclusion: such a pseudo must not go in a hard reg. */
702 EXECUTE_IF_SET_IN_REG_SET (regs_live_at_setjmp
,
703 FIRST_PSEUDO_REGISTER
, i
,
705 if (regno_reg_rtx
[i
] != 0)
707 REG_LIVE_LENGTH (i
) = -1;
708 REG_BASIC_BLOCK (i
) = REG_BLOCK_UNKNOWN
;
717 timevar_pop ((extent
== UPDATE_LIFE_LOCAL
|| blocks
)
718 ? TV_LIFE_UPDATE
: TV_LIFE
);
719 if (ndead
&& dump_file
)
720 fprintf (dump_file
, "deleted %i dead insns\n", ndead
);
724 /* Update life information in all blocks where BB_DIRTY is set. */
727 update_life_info_in_dirty_blocks (enum update_life_extent extent
, int prop_flags
)
729 sbitmap update_life_blocks
= sbitmap_alloc (last_basic_block
);
734 sbitmap_zero (update_life_blocks
);
737 if (extent
== UPDATE_LIFE_LOCAL
)
739 if (bb
->flags
& BB_DIRTY
)
741 SET_BIT (update_life_blocks
, bb
->index
);
747 /* ??? Bootstrap with -march=pentium4 fails to terminate
748 with only a partial life update. */
749 SET_BIT (update_life_blocks
, bb
->index
);
750 if (bb
->flags
& BB_DIRTY
)
756 retval
= update_life_info (update_life_blocks
, extent
, prop_flags
);
758 sbitmap_free (update_life_blocks
);
762 /* Free the variables allocated by find_basic_blocks. */
765 free_basic_block_vars (void)
767 if (basic_block_info
)
770 basic_block_info
= NULL
;
773 last_basic_block
= 0;
775 ENTRY_BLOCK_PTR
->aux
= NULL
;
776 ENTRY_BLOCK_PTR
->global_live_at_end
= NULL
;
777 EXIT_BLOCK_PTR
->aux
= NULL
;
778 EXIT_BLOCK_PTR
->global_live_at_start
= NULL
;
781 /* Delete any insns that copy a register to itself. */
784 delete_noop_moves (void)
792 for (insn
= BB_HEAD (bb
); insn
!= NEXT_INSN (BB_END (bb
)); insn
= next
)
794 next
= NEXT_INSN (insn
);
795 if (INSN_P (insn
) && noop_move_p (insn
))
799 /* If we're about to remove the first insn of a libcall
800 then move the libcall note to the next real insn and
801 update the retval note. */
802 if ((note
= find_reg_note (insn
, REG_LIBCALL
, NULL_RTX
))
803 && XEXP (note
, 0) != insn
)
805 rtx new_libcall_insn
= next_real_insn (insn
);
806 rtx retval_note
= find_reg_note (XEXP (note
, 0),
807 REG_RETVAL
, NULL_RTX
);
808 REG_NOTES (new_libcall_insn
)
809 = gen_rtx_INSN_LIST (REG_LIBCALL
, XEXP (note
, 0),
810 REG_NOTES (new_libcall_insn
));
811 XEXP (retval_note
, 0) = new_libcall_insn
;
814 delete_insn_and_edges (insn
);
819 if (nnoops
&& dump_file
)
820 fprintf (dump_file
, "deleted %i noop moves", nnoops
);
824 /* Delete any jump tables never referenced. We can't delete them at the
825 time of removing tablejump insn as they are referenced by the preceding
826 insns computing the destination, so we delay deleting and garbagecollect
827 them once life information is computed. */
829 delete_dead_jumptables (void)
832 for (insn
= get_insns (); insn
; insn
= next
)
834 next
= NEXT_INSN (insn
);
835 if (GET_CODE (insn
) == CODE_LABEL
836 && LABEL_NUSES (insn
) == LABEL_PRESERVE_P (insn
)
837 && GET_CODE (next
) == JUMP_INSN
838 && (GET_CODE (PATTERN (next
)) == ADDR_VEC
839 || GET_CODE (PATTERN (next
)) == ADDR_DIFF_VEC
))
842 fprintf (dump_file
, "Dead jumptable %i removed\n", INSN_UID (insn
));
843 delete_insn (NEXT_INSN (insn
));
845 next
= NEXT_INSN (next
);
850 /* Determine if the stack pointer is constant over the life of the function.
851 Only useful before prologues have been emitted. */
854 notice_stack_pointer_modification_1 (rtx x
, rtx pat ATTRIBUTE_UNUSED
,
855 void *data ATTRIBUTE_UNUSED
)
857 if (x
== stack_pointer_rtx
858 /* The stack pointer is only modified indirectly as the result
859 of a push until later in flow. See the comments in rtl.texi
860 regarding Embedded Side-Effects on Addresses. */
861 || (GET_CODE (x
) == MEM
862 && GET_RTX_CLASS (GET_CODE (XEXP (x
, 0))) == RTX_AUTOINC
863 && XEXP (XEXP (x
, 0), 0) == stack_pointer_rtx
))
864 current_function_sp_is_unchanging
= 0;
868 notice_stack_pointer_modification (void)
873 /* Assume that the stack pointer is unchanging if alloca hasn't
875 current_function_sp_is_unchanging
= !current_function_calls_alloca
;
876 if (! current_function_sp_is_unchanging
)
880 FOR_BB_INSNS (bb
, insn
)
884 /* Check if insn modifies the stack pointer. */
885 note_stores (PATTERN (insn
),
886 notice_stack_pointer_modification_1
,
888 if (! current_function_sp_is_unchanging
)
894 /* Mark a register in SET. Hard registers in large modes get all
895 of their component registers set as well. */
898 mark_reg (rtx reg
, void *xset
)
900 regset set
= (regset
) xset
;
901 int regno
= REGNO (reg
);
903 if (GET_MODE (reg
) == BLKmode
)
906 SET_REGNO_REG_SET (set
, regno
);
907 if (regno
< FIRST_PSEUDO_REGISTER
)
909 int n
= hard_regno_nregs
[regno
][GET_MODE (reg
)];
911 SET_REGNO_REG_SET (set
, regno
+ n
);
915 /* Mark those regs which are needed at the end of the function as live
916 at the end of the last basic block. */
919 mark_regs_live_at_end (regset set
)
923 /* If exiting needs the right stack value, consider the stack pointer
924 live at the end of the function. */
925 if ((HAVE_epilogue
&& epilogue_completed
)
926 || ! EXIT_IGNORE_STACK
927 || (! FRAME_POINTER_REQUIRED
928 && ! current_function_calls_alloca
929 && flag_omit_frame_pointer
)
930 || current_function_sp_is_unchanging
)
932 SET_REGNO_REG_SET (set
, STACK_POINTER_REGNUM
);
935 /* Mark the frame pointer if needed at the end of the function. If
936 we end up eliminating it, it will be removed from the live list
937 of each basic block by reload. */
939 if (! reload_completed
|| frame_pointer_needed
)
941 SET_REGNO_REG_SET (set
, FRAME_POINTER_REGNUM
);
942 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
943 /* If they are different, also mark the hard frame pointer as live. */
944 if (! LOCAL_REGNO (HARD_FRAME_POINTER_REGNUM
))
945 SET_REGNO_REG_SET (set
, HARD_FRAME_POINTER_REGNUM
);
949 #ifndef PIC_OFFSET_TABLE_REG_CALL_CLOBBERED
950 /* Many architectures have a GP register even without flag_pic.
951 Assume the pic register is not in use, or will be handled by
952 other means, if it is not fixed. */
953 if ((unsigned) PIC_OFFSET_TABLE_REGNUM
!= INVALID_REGNUM
954 && fixed_regs
[PIC_OFFSET_TABLE_REGNUM
])
955 SET_REGNO_REG_SET (set
, PIC_OFFSET_TABLE_REGNUM
);
958 /* Mark all global registers, and all registers used by the epilogue
959 as being live at the end of the function since they may be
960 referenced by our caller. */
961 for (i
= 0; i
< FIRST_PSEUDO_REGISTER
; i
++)
962 if (global_regs
[i
] || EPILOGUE_USES (i
))
963 SET_REGNO_REG_SET (set
, i
);
965 if (HAVE_epilogue
&& epilogue_completed
)
967 /* Mark all call-saved registers that we actually used. */
968 for (i
= 0; i
< FIRST_PSEUDO_REGISTER
; i
++)
969 if (regs_ever_live
[i
] && ! LOCAL_REGNO (i
)
970 && ! TEST_HARD_REG_BIT (regs_invalidated_by_call
, i
))
971 SET_REGNO_REG_SET (set
, i
);
974 #ifdef EH_RETURN_DATA_REGNO
975 /* Mark the registers that will contain data for the handler. */
976 if (reload_completed
&& current_function_calls_eh_return
)
979 unsigned regno
= EH_RETURN_DATA_REGNO(i
);
980 if (regno
== INVALID_REGNUM
)
982 SET_REGNO_REG_SET (set
, regno
);
985 #ifdef EH_RETURN_STACKADJ_RTX
986 if ((! HAVE_epilogue
|| ! epilogue_completed
)
987 && current_function_calls_eh_return
)
989 rtx tmp
= EH_RETURN_STACKADJ_RTX
;
990 if (tmp
&& REG_P (tmp
))
994 #ifdef EH_RETURN_HANDLER_RTX
995 if ((! HAVE_epilogue
|| ! epilogue_completed
)
996 && current_function_calls_eh_return
)
998 rtx tmp
= EH_RETURN_HANDLER_RTX
;
999 if (tmp
&& REG_P (tmp
))
1000 mark_reg (tmp
, set
);
1004 /* Mark function return value. */
1005 diddle_return_value (mark_reg
, set
);
1008 /* Propagate global life info around the graph of basic blocks. Begin
1009 considering blocks with their corresponding bit set in BLOCKS_IN.
1010 If BLOCKS_IN is null, consider it the universal set.
1012 BLOCKS_OUT is set for every block that was changed. */
1015 calculate_global_regs_live (sbitmap blocks_in
, sbitmap blocks_out
, int flags
)
1017 basic_block
*queue
, *qhead
, *qtail
, *qend
, bb
;
1018 regset tmp
, new_live_at_end
, invalidated_by_call
;
1019 regset_head tmp_head
, invalidated_by_call_head
;
1020 regset_head new_live_at_end_head
;
1023 /* Some passes used to forget clear aux field of basic block causing
1024 sick behavior here. */
1025 #ifdef ENABLE_CHECKING
1026 FOR_BB_BETWEEN (bb
, ENTRY_BLOCK_PTR
, NULL
, next_bb
)
1031 tmp
= INITIALIZE_REG_SET (tmp_head
);
1032 new_live_at_end
= INITIALIZE_REG_SET (new_live_at_end_head
);
1033 invalidated_by_call
= INITIALIZE_REG_SET (invalidated_by_call_head
);
1035 /* Inconveniently, this is only readily available in hard reg set form. */
1036 for (i
= 0; i
< FIRST_PSEUDO_REGISTER
; ++i
)
1037 if (TEST_HARD_REG_BIT (regs_invalidated_by_call
, i
))
1038 SET_REGNO_REG_SET (invalidated_by_call
, i
);
1040 /* Create a worklist. Allocate an extra slot for ENTRY_BLOCK, and one
1041 because the `head == tail' style test for an empty queue doesn't
1042 work with a full queue. */
1043 queue
= xmalloc ((n_basic_blocks
+ 2) * sizeof (*queue
));
1045 qhead
= qend
= queue
+ n_basic_blocks
+ 2;
1047 /* Queue the blocks set in the initial mask. Do this in reverse block
1048 number order so that we are more likely for the first round to do
1049 useful work. We use AUX non-null to flag that the block is queued. */
1053 if (TEST_BIT (blocks_in
, bb
->index
))
1068 /* We clean aux when we remove the initially-enqueued bbs, but we
1069 don't enqueue ENTRY and EXIT initially, so clean them upfront and
1071 ENTRY_BLOCK_PTR
->aux
= EXIT_BLOCK_PTR
->aux
= NULL
;
1074 sbitmap_zero (blocks_out
);
1076 /* We work through the queue until there are no more blocks. What
1077 is live at the end of this block is precisely the union of what
1078 is live at the beginning of all its successors. So, we set its
1079 GLOBAL_LIVE_AT_END field based on the GLOBAL_LIVE_AT_START field
1080 for its successors. Then, we compute GLOBAL_LIVE_AT_START for
1081 this block by walking through the instructions in this block in
1082 reverse order and updating as we go. If that changed
1083 GLOBAL_LIVE_AT_START, we add the predecessors of the block to the
1084 queue; they will now need to recalculate GLOBAL_LIVE_AT_END.
1086 We are guaranteed to terminate, because GLOBAL_LIVE_AT_START
1087 never shrinks. If a register appears in GLOBAL_LIVE_AT_START, it
1088 must either be live at the end of the block, or used within the
1089 block. In the latter case, it will certainly never disappear
1090 from GLOBAL_LIVE_AT_START. In the former case, the register
1091 could go away only if it disappeared from GLOBAL_LIVE_AT_START
1092 for one of the successor blocks. By induction, that cannot
1094 while (qhead
!= qtail
)
1096 int rescan
, changed
;
1105 /* Begin by propagating live_at_start from the successor blocks. */
1106 CLEAR_REG_SET (new_live_at_end
);
1109 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
1111 basic_block sb
= e
->dest
;
1113 /* Call-clobbered registers die across exception and
1115 /* ??? Abnormal call edges ignored for the moment, as this gets
1116 confused by sibling call edges, which crashes reg-stack. */
1117 if (e
->flags
& EDGE_EH
)
1119 bitmap_operation (tmp
, sb
->global_live_at_start
,
1120 invalidated_by_call
, BITMAP_AND_COMPL
);
1121 IOR_REG_SET (new_live_at_end
, tmp
);
1124 IOR_REG_SET (new_live_at_end
, sb
->global_live_at_start
);
1126 /* If a target saves one register in another (instead of on
1127 the stack) the save register will need to be live for EH. */
1128 if (e
->flags
& EDGE_EH
)
1129 for (i
= 0; i
< FIRST_PSEUDO_REGISTER
; i
++)
1131 SET_REGNO_REG_SET (new_live_at_end
, i
);
1135 /* This might be a noreturn function that throws. And
1136 even if it isn't, getting the unwind info right helps
1138 for (i
= 0; i
< FIRST_PSEUDO_REGISTER
; i
++)
1140 SET_REGNO_REG_SET (new_live_at_end
, i
);
1143 /* The all-important stack pointer must always be live. */
1144 SET_REGNO_REG_SET (new_live_at_end
, STACK_POINTER_REGNUM
);
1146 /* Before reload, there are a few registers that must be forced
1147 live everywhere -- which might not already be the case for
1148 blocks within infinite loops. */
1149 if (! reload_completed
)
1151 /* Any reference to any pseudo before reload is a potential
1152 reference of the frame pointer. */
1153 SET_REGNO_REG_SET (new_live_at_end
, FRAME_POINTER_REGNUM
);
1155 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
1156 /* Pseudos with argument area equivalences may require
1157 reloading via the argument pointer. */
1158 if (fixed_regs
[ARG_POINTER_REGNUM
])
1159 SET_REGNO_REG_SET (new_live_at_end
, ARG_POINTER_REGNUM
);
1162 /* Any constant, or pseudo with constant equivalences, may
1163 require reloading from memory using the pic register. */
1164 if ((unsigned) PIC_OFFSET_TABLE_REGNUM
!= INVALID_REGNUM
1165 && fixed_regs
[PIC_OFFSET_TABLE_REGNUM
])
1166 SET_REGNO_REG_SET (new_live_at_end
, PIC_OFFSET_TABLE_REGNUM
);
1169 if (bb
== ENTRY_BLOCK_PTR
)
1171 COPY_REG_SET (bb
->global_live_at_end
, new_live_at_end
);
1175 /* On our first pass through this block, we'll go ahead and continue.
1176 Recognize first pass by local_set NULL. On subsequent passes, we
1177 get to skip out early if live_at_end wouldn't have changed. */
1179 if (bb
->local_set
== NULL
)
1181 bb
->local_set
= OBSTACK_ALLOC_REG_SET (&flow_obstack
);
1182 bb
->cond_local_set
= OBSTACK_ALLOC_REG_SET (&flow_obstack
);
1187 /* If any bits were removed from live_at_end, we'll have to
1188 rescan the block. This wouldn't be necessary if we had
1189 precalculated local_live, however with PROP_SCAN_DEAD_CODE
1190 local_live is really dependent on live_at_end. */
1191 CLEAR_REG_SET (tmp
);
1192 rescan
= bitmap_operation (tmp
, bb
->global_live_at_end
,
1193 new_live_at_end
, BITMAP_AND_COMPL
);
1197 /* If any of the registers in the new live_at_end set are
1198 conditionally set in this basic block, we must rescan.
1199 This is because conditional lifetimes at the end of the
1200 block do not just take the live_at_end set into account,
1201 but also the liveness at the start of each successor
1202 block. We can miss changes in those sets if we only
1203 compare the new live_at_end against the previous one. */
1204 CLEAR_REG_SET (tmp
);
1205 rescan
= bitmap_operation (tmp
, new_live_at_end
,
1206 bb
->cond_local_set
, BITMAP_AND
);
1211 /* Find the set of changed bits. Take this opportunity
1212 to notice that this set is empty and early out. */
1213 CLEAR_REG_SET (tmp
);
1214 changed
= bitmap_operation (tmp
, bb
->global_live_at_end
,
1215 new_live_at_end
, BITMAP_XOR
);
1219 /* If any of the changed bits overlap with local_set,
1220 we'll have to rescan the block. Detect overlap by
1221 the AND with ~local_set turning off bits. */
1222 rescan
= bitmap_operation (tmp
, tmp
, bb
->local_set
,
1227 /* Let our caller know that BB changed enough to require its
1228 death notes updated. */
1230 SET_BIT (blocks_out
, bb
->index
);
1234 /* Add to live_at_start the set of all registers in
1235 new_live_at_end that aren't in the old live_at_end. */
1237 bitmap_operation (tmp
, new_live_at_end
, bb
->global_live_at_end
,
1239 COPY_REG_SET (bb
->global_live_at_end
, new_live_at_end
);
1241 changed
= bitmap_operation (bb
->global_live_at_start
,
1242 bb
->global_live_at_start
,
1249 COPY_REG_SET (bb
->global_live_at_end
, new_live_at_end
);
1251 /* Rescan the block insn by insn to turn (a copy of) live_at_end
1252 into live_at_start. */
1253 propagate_block (bb
, new_live_at_end
, bb
->local_set
,
1254 bb
->cond_local_set
, flags
);
1256 /* If live_at start didn't change, no need to go farther. */
1257 if (REG_SET_EQUAL_P (bb
->global_live_at_start
, new_live_at_end
))
1260 COPY_REG_SET (bb
->global_live_at_start
, new_live_at_end
);
1263 /* Queue all predecessors of BB so that we may re-examine
1264 their live_at_end. */
1265 for (e
= bb
->pred
; e
; e
= e
->pred_next
)
1267 basic_block pb
= e
->src
;
1268 if (pb
->aux
== NULL
)
1279 FREE_REG_SET (new_live_at_end
);
1280 FREE_REG_SET (invalidated_by_call
);
1284 EXECUTE_IF_SET_IN_SBITMAP (blocks_out
, 0, i
,
1286 basic_block bb
= BASIC_BLOCK (i
);
1287 FREE_REG_SET (bb
->local_set
);
1288 FREE_REG_SET (bb
->cond_local_set
);
1295 FREE_REG_SET (bb
->local_set
);
1296 FREE_REG_SET (bb
->cond_local_set
);
1304 /* This structure is used to pass parameters to and from the
1305 the function find_regno_partial(). It is used to pass in the
1306 register number we are looking, as well as to return any rtx
1310 unsigned regno_to_find
;
1312 } find_regno_partial_param
;
1315 /* Find the rtx for the reg numbers specified in 'data' if it is
1316 part of an expression which only uses part of the register. Return
1317 it in the structure passed in. */
1319 find_regno_partial (rtx
*ptr
, void *data
)
1321 find_regno_partial_param
*param
= (find_regno_partial_param
*)data
;
1322 unsigned reg
= param
->regno_to_find
;
1323 param
->retval
= NULL_RTX
;
1325 if (*ptr
== NULL_RTX
)
1328 switch (GET_CODE (*ptr
))
1332 case STRICT_LOW_PART
:
1333 if (GET_CODE (XEXP (*ptr
, 0)) == REG
&& REGNO (XEXP (*ptr
, 0)) == reg
)
1335 param
->retval
= XEXP (*ptr
, 0);
1341 if (GET_CODE (SUBREG_REG (*ptr
)) == REG
1342 && REGNO (SUBREG_REG (*ptr
)) == reg
)
1344 param
->retval
= SUBREG_REG (*ptr
);
1356 /* Process all immediate successors of the entry block looking for pseudo
1357 registers which are live on entry. Find all of those whose first
1358 instance is a partial register reference of some kind, and initialize
1359 them to 0 after the entry block. This will prevent bit sets within
1360 registers whose value is unknown, and may contain some kind of sticky
1361 bits we don't want. */
1364 initialize_uninitialized_subregs (void)
1368 int reg
, did_something
= 0;
1369 find_regno_partial_param param
;
1371 for (e
= ENTRY_BLOCK_PTR
->succ
; e
; e
= e
->succ_next
)
1373 basic_block bb
= e
->dest
;
1374 regset map
= bb
->global_live_at_start
;
1375 EXECUTE_IF_SET_IN_REG_SET (map
,
1376 FIRST_PSEUDO_REGISTER
, reg
,
1378 int uid
= REGNO_FIRST_UID (reg
);
1381 /* Find an insn which mentions the register we are looking for.
1382 Its preferable to have an instance of the register's rtl since
1383 there may be various flags set which we need to duplicate.
1384 If we can't find it, its probably an automatic whose initial
1385 value doesn't matter, or hopefully something we don't care about. */
1386 for (i
= get_insns (); i
&& INSN_UID (i
) != uid
; i
= NEXT_INSN (i
))
1390 /* Found the insn, now get the REG rtx, if we can. */
1391 param
.regno_to_find
= reg
;
1392 for_each_rtx (&i
, find_regno_partial
, ¶m
);
1393 if (param
.retval
!= NULL_RTX
)
1396 emit_move_insn (param
.retval
,
1397 CONST0_RTX (GET_MODE (param
.retval
)));
1398 insn
= get_insns ();
1400 insert_insn_on_edge (insn
, e
);
1408 commit_edge_insertions ();
1409 return did_something
;
1413 /* Subroutines of life analysis. */
1415 /* Allocate the permanent data structures that represent the results
1416 of life analysis. Not static since used also for stupid life analysis. */
1419 allocate_bb_life_data (void)
1423 FOR_BB_BETWEEN (bb
, ENTRY_BLOCK_PTR
, NULL
, next_bb
)
1425 bb
->global_live_at_start
= OBSTACK_ALLOC_REG_SET (&flow_obstack
);
1426 bb
->global_live_at_end
= OBSTACK_ALLOC_REG_SET (&flow_obstack
);
1429 regs_live_at_setjmp
= OBSTACK_ALLOC_REG_SET (&flow_obstack
);
1433 allocate_reg_life_data (void)
1437 max_regno
= max_reg_num ();
1440 reg_deaths
= xcalloc (sizeof (*reg_deaths
), max_regno
);
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;
1456 REG_BASIC_BLOCK (i
) = REG_BLOCK_UNKNOWN
;
1460 /* Delete dead instructions for propagate_block. */
1463 propagate_block_delete_insn (rtx insn
)
1465 rtx inote
= find_reg_note (insn
, REG_LABEL
, NULL_RTX
);
1467 /* If the insn referred to a label, and that label was attached to
1468 an ADDR_VEC, it's safe to delete the ADDR_VEC. In fact, it's
1469 pretty much mandatory to delete it, because the ADDR_VEC may be
1470 referencing labels that no longer exist.
1472 INSN may reference a deleted label, particularly when a jump
1473 table has been optimized into a direct jump. There's no
1474 real good way to fix up the reference to the deleted label
1475 when the label is deleted, so we just allow it here. */
1477 if (inote
&& GET_CODE (inote
) == CODE_LABEL
)
1479 rtx label
= XEXP (inote
, 0);
1482 /* The label may be forced if it has been put in the constant
1483 pool. If that is the only use we must discard the table
1484 jump following it, but not the label itself. */
1485 if (LABEL_NUSES (label
) == 1 + LABEL_PRESERVE_P (label
)
1486 && (next
= next_nonnote_insn (label
)) != NULL
1487 && GET_CODE (next
) == JUMP_INSN
1488 && (GET_CODE (PATTERN (next
)) == ADDR_VEC
1489 || GET_CODE (PATTERN (next
)) == ADDR_DIFF_VEC
))
1491 rtx pat
= PATTERN (next
);
1492 int diff_vec_p
= GET_CODE (pat
) == ADDR_DIFF_VEC
;
1493 int len
= XVECLEN (pat
, diff_vec_p
);
1496 for (i
= 0; i
< len
; i
++)
1497 LABEL_NUSES (XEXP (XVECEXP (pat
, diff_vec_p
, i
), 0))--;
1499 delete_insn_and_edges (next
);
1504 delete_insn_and_edges (insn
);
1508 /* Delete dead libcalls for propagate_block. Return the insn
1509 before the libcall. */
1512 propagate_block_delete_libcall (rtx insn
, rtx note
)
1514 rtx first
= XEXP (note
, 0);
1515 rtx before
= PREV_INSN (first
);
1517 delete_insn_chain_and_edges (first
, insn
);
1522 /* Update the life-status of regs for one insn. Return the previous insn. */
1525 propagate_one_insn (struct propagate_block_info
*pbi
, rtx insn
)
1527 rtx prev
= PREV_INSN (insn
);
1528 int flags
= pbi
->flags
;
1529 int insn_is_dead
= 0;
1530 int libcall_is_dead
= 0;
1534 if (! INSN_P (insn
))
1537 note
= find_reg_note (insn
, REG_RETVAL
, NULL_RTX
);
1538 if (flags
& PROP_SCAN_DEAD_CODE
)
1540 insn_is_dead
= insn_dead_p (pbi
, PATTERN (insn
), 0, REG_NOTES (insn
));
1541 libcall_is_dead
= (insn_is_dead
&& note
!= 0
1542 && libcall_dead_p (pbi
, note
, insn
));
1545 /* If an instruction consists of just dead store(s) on final pass,
1547 if ((flags
& PROP_KILL_DEAD_CODE
) && insn_is_dead
)
1549 /* If we're trying to delete a prologue or epilogue instruction
1550 that isn't flagged as possibly being dead, something is wrong.
1551 But if we are keeping the stack pointer depressed, we might well
1552 be deleting insns that are used to compute the amount to update
1553 it by, so they are fine. */
1554 if (reload_completed
1555 && !(TREE_CODE (TREE_TYPE (current_function_decl
)) == FUNCTION_TYPE
1556 && (TYPE_RETURNS_STACK_DEPRESSED
1557 (TREE_TYPE (current_function_decl
))))
1558 && (((HAVE_epilogue
|| HAVE_prologue
)
1559 && prologue_epilogue_contains (insn
))
1560 || (HAVE_sibcall_epilogue
1561 && sibcall_epilogue_contains (insn
)))
1562 && find_reg_note (insn
, REG_MAYBE_DEAD
, NULL_RTX
) == 0)
1563 fatal_insn ("Attempt to delete prologue/epilogue insn:", insn
);
1565 /* Record sets. Do this even for dead instructions, since they
1566 would have killed the values if they hadn't been deleted. */
1567 mark_set_regs (pbi
, PATTERN (insn
), insn
);
1569 /* CC0 is now known to be dead. Either this insn used it,
1570 in which case it doesn't anymore, or clobbered it,
1571 so the next insn can't use it. */
1574 if (libcall_is_dead
)
1575 prev
= propagate_block_delete_libcall ( insn
, note
);
1579 /* If INSN contains a RETVAL note and is dead, but the libcall
1580 as a whole is not dead, then we want to remove INSN, but
1581 not the whole libcall sequence.
1583 However, we need to also remove the dangling REG_LIBCALL
1584 note so that we do not have mis-matched LIBCALL/RETVAL
1585 notes. In theory we could find a new location for the
1586 REG_RETVAL note, but it hardly seems worth the effort.
1588 NOTE at this point will be the RETVAL note if it exists. */
1594 = find_reg_note (XEXP (note
, 0), REG_LIBCALL
, NULL_RTX
);
1595 remove_note (XEXP (note
, 0), libcall_note
);
1598 /* Similarly if INSN contains a LIBCALL note, remove the
1599 dangling REG_RETVAL note. */
1600 note
= find_reg_note (insn
, REG_LIBCALL
, NULL_RTX
);
1606 = find_reg_note (XEXP (note
, 0), REG_RETVAL
, NULL_RTX
);
1607 remove_note (XEXP (note
, 0), retval_note
);
1610 /* Now delete INSN. */
1611 propagate_block_delete_insn (insn
);
1617 /* See if this is an increment or decrement that can be merged into
1618 a following memory address. */
1621 rtx x
= single_set (insn
);
1623 /* Does this instruction increment or decrement a register? */
1624 if ((flags
& PROP_AUTOINC
)
1626 && GET_CODE (SET_DEST (x
)) == REG
1627 && (GET_CODE (SET_SRC (x
)) == PLUS
1628 || GET_CODE (SET_SRC (x
)) == MINUS
)
1629 && XEXP (SET_SRC (x
), 0) == SET_DEST (x
)
1630 && GET_CODE (XEXP (SET_SRC (x
), 1)) == CONST_INT
1631 /* Ok, look for a following memory ref we can combine with.
1632 If one is found, change the memory ref to a PRE_INC
1633 or PRE_DEC, cancel this insn, and return 1.
1634 Return 0 if nothing has been done. */
1635 && try_pre_increment_1 (pbi
, insn
))
1638 #endif /* AUTO_INC_DEC */
1640 CLEAR_REG_SET (pbi
->new_set
);
1642 /* If this is not the final pass, and this insn is copying the value of
1643 a library call and it's dead, don't scan the insns that perform the
1644 library call, so that the call's arguments are not marked live. */
1645 if (libcall_is_dead
)
1647 /* Record the death of the dest reg. */
1648 mark_set_regs (pbi
, PATTERN (insn
), insn
);
1650 insn
= XEXP (note
, 0);
1651 return PREV_INSN (insn
);
1653 else if (GET_CODE (PATTERN (insn
)) == SET
1654 && SET_DEST (PATTERN (insn
)) == stack_pointer_rtx
1655 && GET_CODE (SET_SRC (PATTERN (insn
))) == PLUS
1656 && XEXP (SET_SRC (PATTERN (insn
)), 0) == stack_pointer_rtx
1657 && GET_CODE (XEXP (SET_SRC (PATTERN (insn
)), 1)) == CONST_INT
)
1659 /* We have an insn to pop a constant amount off the stack.
1660 (Such insns use PLUS regardless of the direction of the stack,
1661 and any insn to adjust the stack by a constant is always a pop
1663 These insns, if not dead stores, have no effect on life, though
1664 they do have an effect on the memory stores we are tracking. */
1665 invalidate_mems_from_set (pbi
, stack_pointer_rtx
);
1666 /* Still, we need to update local_set, lest ifcvt.c:dead_or_predicable
1667 concludes that the stack pointer is not modified. */
1668 mark_set_regs (pbi
, PATTERN (insn
), insn
);
1673 /* Any regs live at the time of a call instruction must not go
1674 in a register clobbered by calls. Find all regs now live and
1675 record this for them. */
1677 if (GET_CODE (insn
) == CALL_INSN
&& (flags
& PROP_REG_INFO
))
1678 EXECUTE_IF_SET_IN_REG_SET (pbi
->reg_live
, 0, i
,
1679 { REG_N_CALLS_CROSSED (i
)++; });
1681 /* Record sets. Do this even for dead instructions, since they
1682 would have killed the values if they hadn't been deleted. */
1683 mark_set_regs (pbi
, PATTERN (insn
), insn
);
1685 if (GET_CODE (insn
) == CALL_INSN
)
1693 if (GET_CODE (PATTERN (insn
)) == COND_EXEC
)
1694 cond
= COND_EXEC_TEST (PATTERN (insn
));
1696 /* Non-constant calls clobber memory, constant calls do not
1697 clobber memory, though they may clobber outgoing arguments
1699 if (! CONST_OR_PURE_CALL_P (insn
))
1701 free_EXPR_LIST_list (&pbi
->mem_set_list
);
1702 pbi
->mem_set_list_len
= 0;
1705 invalidate_mems_from_set (pbi
, stack_pointer_rtx
);
1707 /* There may be extra registers to be clobbered. */
1708 for (note
= CALL_INSN_FUNCTION_USAGE (insn
);
1710 note
= XEXP (note
, 1))
1711 if (GET_CODE (XEXP (note
, 0)) == CLOBBER
)
1712 mark_set_1 (pbi
, CLOBBER
, XEXP (XEXP (note
, 0), 0),
1713 cond
, insn
, pbi
->flags
);
1715 /* Calls change all call-used and global registers; sibcalls do not
1716 clobber anything that must be preserved at end-of-function,
1717 except for return values. */
1719 sibcall_p
= SIBLING_CALL_P (insn
);
1720 live_at_end
= EXIT_BLOCK_PTR
->global_live_at_start
;
1721 for (i
= 0; i
< FIRST_PSEUDO_REGISTER
; i
++)
1722 if (TEST_HARD_REG_BIT (regs_invalidated_by_call
, i
)
1724 && REGNO_REG_SET_P (live_at_end
, i
)
1725 && ! refers_to_regno_p (i
, i
+1,
1726 current_function_return_rtx
,
1729 enum rtx_code code
= global_regs
[i
] ? SET
: CLOBBER
;
1730 /* We do not want REG_UNUSED notes for these registers. */
1731 mark_set_1 (pbi
, code
, regno_reg_rtx
[i
], cond
, insn
,
1732 pbi
->flags
& ~(PROP_DEATH_NOTES
| PROP_REG_INFO
));
1736 /* If an insn doesn't use CC0, it becomes dead since we assume
1737 that every insn clobbers it. So show it dead here;
1738 mark_used_regs will set it live if it is referenced. */
1743 mark_used_regs (pbi
, PATTERN (insn
), NULL_RTX
, insn
);
1744 if ((flags
& PROP_EQUAL_NOTES
)
1745 && ((note
= find_reg_note (insn
, REG_EQUAL
, NULL_RTX
))
1746 || (note
= find_reg_note (insn
, REG_EQUIV
, NULL_RTX
))))
1747 mark_used_regs (pbi
, XEXP (note
, 0), NULL_RTX
, insn
);
1749 /* Sometimes we may have inserted something before INSN (such as a move)
1750 when we make an auto-inc. So ensure we will scan those insns. */
1752 prev
= PREV_INSN (insn
);
1755 if (! insn_is_dead
&& GET_CODE (insn
) == CALL_INSN
)
1761 if (GET_CODE (PATTERN (insn
)) == COND_EXEC
)
1762 cond
= COND_EXEC_TEST (PATTERN (insn
));
1764 /* Calls use their arguments, and may clobber memory which
1765 address involves some register. */
1766 for (note
= CALL_INSN_FUNCTION_USAGE (insn
);
1768 note
= XEXP (note
, 1))
1769 /* We find USE or CLOBBER entities in a FUNCTION_USAGE list: both
1770 of which mark_used_regs knows how to handle. */
1771 mark_used_regs (pbi
, XEXP (XEXP (note
, 0), 0), cond
, insn
);
1773 /* The stack ptr is used (honorarily) by a CALL insn. */
1774 if ((flags
& PROP_REG_INFO
)
1775 && !REGNO_REG_SET_P (pbi
->reg_live
, STACK_POINTER_REGNUM
))
1776 reg_deaths
[STACK_POINTER_REGNUM
] = pbi
->insn_num
;
1777 SET_REGNO_REG_SET (pbi
->reg_live
, STACK_POINTER_REGNUM
);
1779 /* Calls may also reference any of the global registers,
1780 so they are made live. */
1781 for (i
= 0; i
< FIRST_PSEUDO_REGISTER
; i
++)
1783 mark_used_reg (pbi
, regno_reg_rtx
[i
], cond
, insn
);
1792 /* Initialize a propagate_block_info struct for public consumption.
1793 Note that the structure itself is opaque to this file, but that
1794 the user can use the regsets provided here. */
1796 struct propagate_block_info
*
1797 init_propagate_block_info (basic_block bb
, regset live
, regset local_set
,
1798 regset cond_local_set
, int flags
)
1800 struct propagate_block_info
*pbi
= xmalloc (sizeof (*pbi
));
1803 pbi
->reg_live
= live
;
1804 pbi
->mem_set_list
= NULL_RTX
;
1805 pbi
->mem_set_list_len
= 0;
1806 pbi
->local_set
= local_set
;
1807 pbi
->cond_local_set
= cond_local_set
;
1812 if (flags
& (PROP_LOG_LINKS
| PROP_AUTOINC
))
1813 pbi
->reg_next_use
= xcalloc (max_reg_num (), sizeof (rtx
));
1815 pbi
->reg_next_use
= NULL
;
1817 pbi
->new_set
= BITMAP_XMALLOC ();
1819 #ifdef HAVE_conditional_execution
1820 pbi
->reg_cond_dead
= splay_tree_new (splay_tree_compare_ints
, NULL
,
1821 free_reg_cond_life_info
);
1822 pbi
->reg_cond_reg
= BITMAP_XMALLOC ();
1824 /* If this block ends in a conditional branch, for each register
1825 live from one side of the branch and not the other, record the
1826 register as conditionally dead. */
1827 if (GET_CODE (BB_END (bb
)) == JUMP_INSN
1828 && any_condjump_p (BB_END (bb
)))
1830 regset_head diff_head
;
1831 regset diff
= INITIALIZE_REG_SET (diff_head
);
1832 basic_block bb_true
, bb_false
;
1835 /* Identify the successor blocks. */
1836 bb_true
= bb
->succ
->dest
;
1837 if (bb
->succ
->succ_next
!= NULL
)
1839 bb_false
= bb
->succ
->succ_next
->dest
;
1841 if (bb
->succ
->flags
& EDGE_FALLTHRU
)
1843 basic_block t
= bb_false
;
1847 else if (! (bb
->succ
->succ_next
->flags
& EDGE_FALLTHRU
))
1852 /* This can happen with a conditional jump to the next insn. */
1853 if (JUMP_LABEL (BB_END (bb
)) != BB_HEAD (bb_true
))
1856 /* Simplest way to do nothing. */
1860 /* Compute which register lead different lives in the successors. */
1861 if (bitmap_operation (diff
, bb_true
->global_live_at_start
,
1862 bb_false
->global_live_at_start
, BITMAP_XOR
))
1864 /* Extract the condition from the branch. */
1865 rtx set_src
= SET_SRC (pc_set (BB_END (bb
)));
1866 rtx cond_true
= XEXP (set_src
, 0);
1867 rtx reg
= XEXP (cond_true
, 0);
1869 if (GET_CODE (reg
) == SUBREG
)
1870 reg
= SUBREG_REG (reg
);
1872 /* We can only track conditional lifetimes if the condition is
1873 in the form of a comparison of a register against zero.
1874 If the condition is more complex than that, then it is safe
1875 not to record any information. */
1876 if (GET_CODE (reg
) == REG
1877 && XEXP (cond_true
, 1) == const0_rtx
)
1880 = gen_rtx_fmt_ee (reverse_condition (GET_CODE (cond_true
)),
1881 GET_MODE (cond_true
), XEXP (cond_true
, 0),
1882 XEXP (cond_true
, 1));
1883 if (GET_CODE (XEXP (set_src
, 1)) == PC
)
1886 cond_false
= cond_true
;
1890 SET_REGNO_REG_SET (pbi
->reg_cond_reg
, REGNO (reg
));
1892 /* For each such register, mark it conditionally dead. */
1893 EXECUTE_IF_SET_IN_REG_SET
1896 struct reg_cond_life_info
*rcli
;
1899 rcli
= xmalloc (sizeof (*rcli
));
1901 if (REGNO_REG_SET_P (bb_true
->global_live_at_start
, i
))
1905 rcli
->condition
= cond
;
1906 rcli
->stores
= const0_rtx
;
1907 rcli
->orig_condition
= cond
;
1909 splay_tree_insert (pbi
->reg_cond_dead
, i
,
1910 (splay_tree_value
) rcli
);
1915 FREE_REG_SET (diff
);
1919 /* If this block has no successors, any stores to the frame that aren't
1920 used later in the block are dead. So make a pass over the block
1921 recording any such that are made and show them dead at the end. We do
1922 a very conservative and simple job here. */
1924 && ! (TREE_CODE (TREE_TYPE (current_function_decl
)) == FUNCTION_TYPE
1925 && (TYPE_RETURNS_STACK_DEPRESSED
1926 (TREE_TYPE (current_function_decl
))))
1927 && (flags
& PROP_SCAN_DEAD_STORES
)
1928 && (bb
->succ
== NULL
1929 || (bb
->succ
->succ_next
== NULL
1930 && bb
->succ
->dest
== EXIT_BLOCK_PTR
1931 && ! current_function_calls_eh_return
)))
1934 for (insn
= BB_END (bb
); insn
!= BB_HEAD (bb
); insn
= PREV_INSN (insn
))
1935 if (GET_CODE (insn
) == INSN
1936 && (set
= single_set (insn
))
1937 && GET_CODE (SET_DEST (set
)) == MEM
)
1939 rtx mem
= SET_DEST (set
);
1940 rtx canon_mem
= canon_rtx (mem
);
1942 if (XEXP (canon_mem
, 0) == frame_pointer_rtx
1943 || (GET_CODE (XEXP (canon_mem
, 0)) == PLUS
1944 && XEXP (XEXP (canon_mem
, 0), 0) == frame_pointer_rtx
1945 && GET_CODE (XEXP (XEXP (canon_mem
, 0), 1)) == CONST_INT
))
1946 add_to_mem_set_list (pbi
, canon_mem
);
1953 /* Release a propagate_block_info struct. */
1956 free_propagate_block_info (struct propagate_block_info
*pbi
)
1958 free_EXPR_LIST_list (&pbi
->mem_set_list
);
1960 BITMAP_XFREE (pbi
->new_set
);
1962 #ifdef HAVE_conditional_execution
1963 splay_tree_delete (pbi
->reg_cond_dead
);
1964 BITMAP_XFREE (pbi
->reg_cond_reg
);
1967 if (pbi
->flags
& PROP_REG_INFO
)
1969 int num
= pbi
->insn_num
;
1972 EXECUTE_IF_SET_IN_REG_SET (pbi
->reg_live
, 0, i
,
1973 { REG_LIVE_LENGTH (i
) += num
- reg_deaths
[i
];
1977 if (pbi
->reg_next_use
)
1978 free (pbi
->reg_next_use
);
1983 /* Compute the registers live at the beginning of a basic block BB from
1984 those live at the end.
1986 When called, REG_LIVE contains those live at the end. On return, it
1987 contains those live at the beginning.
1989 LOCAL_SET, if non-null, will be set with all registers killed
1990 unconditionally by this basic block.
1991 Likewise, COND_LOCAL_SET, if non-null, will be set with all registers
1992 killed conditionally by this basic block. If there is any unconditional
1993 set of a register, then the corresponding bit will be set in LOCAL_SET
1994 and cleared in COND_LOCAL_SET.
1995 It is valid for LOCAL_SET and COND_LOCAL_SET to be the same set. In this
1996 case, the resulting set will be equal to the union of the two sets that
1997 would otherwise be computed.
1999 Return nonzero if an INSN is deleted (i.e. by dead code removal). */
2002 propagate_block (basic_block bb
, regset live
, regset local_set
,
2003 regset cond_local_set
, int flags
)
2005 struct propagate_block_info
*pbi
;
2009 pbi
= init_propagate_block_info (bb
, live
, local_set
, cond_local_set
, flags
);
2011 if (flags
& PROP_REG_INFO
)
2015 /* Process the regs live at the end of the block.
2016 Mark them as not local to any one basic block. */
2017 EXECUTE_IF_SET_IN_REG_SET (live
, 0, i
,
2018 { REG_BASIC_BLOCK (i
) = REG_BLOCK_GLOBAL
; });
2021 /* Scan the block an insn at a time from end to beginning. */
2024 for (insn
= BB_END (bb
); ; insn
= prev
)
2026 /* If this is a call to `setjmp' et al, warn if any
2027 non-volatile datum is live. */
2028 if ((flags
& PROP_REG_INFO
)
2029 && GET_CODE (insn
) == CALL_INSN
2030 && find_reg_note (insn
, REG_SETJMP
, NULL
))
2031 IOR_REG_SET (regs_live_at_setjmp
, pbi
->reg_live
);
2033 prev
= propagate_one_insn (pbi
, insn
);
2035 changed
|= insn
!= get_insns ();
2037 changed
|= NEXT_INSN (prev
) != insn
;
2039 if (insn
== BB_HEAD (bb
))
2043 free_propagate_block_info (pbi
);
2048 /* Return 1 if X (the body of an insn, or part of it) is just dead stores
2049 (SET expressions whose destinations are registers dead after the insn).
2050 NEEDED is the regset that says which regs are alive after the insn.
2052 Unless CALL_OK is nonzero, an insn is needed if it contains a CALL.
2054 If X is the entire body of an insn, NOTES contains the reg notes
2055 pertaining to the insn. */
2058 insn_dead_p (struct propagate_block_info
*pbi
, rtx x
, int call_ok
,
2059 rtx notes ATTRIBUTE_UNUSED
)
2061 enum rtx_code code
= GET_CODE (x
);
2063 /* Don't eliminate insns that may trap. */
2064 if (flag_non_call_exceptions
&& may_trap_p (x
))
2068 /* As flow is invoked after combine, we must take existing AUTO_INC
2069 expressions into account. */
2070 for (; notes
; notes
= XEXP (notes
, 1))
2072 if (REG_NOTE_KIND (notes
) == REG_INC
)
2074 int regno
= REGNO (XEXP (notes
, 0));
2076 /* Don't delete insns to set global regs. */
2077 if ((regno
< FIRST_PSEUDO_REGISTER
&& global_regs
[regno
])
2078 || REGNO_REG_SET_P (pbi
->reg_live
, regno
))
2084 /* If setting something that's a reg or part of one,
2085 see if that register's altered value will be live. */
2089 rtx r
= SET_DEST (x
);
2092 if (GET_CODE (r
) == CC0
)
2093 return ! pbi
->cc0_live
;
2096 /* A SET that is a subroutine call cannot be dead. */
2097 if (GET_CODE (SET_SRC (x
)) == CALL
)
2103 /* Don't eliminate loads from volatile memory or volatile asms. */
2104 else if (volatile_refs_p (SET_SRC (x
)))
2107 if (GET_CODE (r
) == MEM
)
2111 if (MEM_VOLATILE_P (r
) || GET_MODE (r
) == BLKmode
)
2114 canon_r
= canon_rtx (r
);
2116 /* Walk the set of memory locations we are currently tracking
2117 and see if one is an identical match to this memory location.
2118 If so, this memory write is dead (remember, we're walking
2119 backwards from the end of the block to the start). Since
2120 rtx_equal_p does not check the alias set or flags, we also
2121 must have the potential for them to conflict (anti_dependence). */
2122 for (temp
= pbi
->mem_set_list
; temp
!= 0; temp
= XEXP (temp
, 1))
2123 if (unchanging_anti_dependence (r
, XEXP (temp
, 0)))
2125 rtx mem
= XEXP (temp
, 0);
2127 if (rtx_equal_p (XEXP (canon_r
, 0), XEXP (mem
, 0))
2128 && (GET_MODE_SIZE (GET_MODE (canon_r
))
2129 <= GET_MODE_SIZE (GET_MODE (mem
))))
2133 /* Check if memory reference matches an auto increment. Only
2134 post increment/decrement or modify are valid. */
2135 if (GET_MODE (mem
) == GET_MODE (r
)
2136 && (GET_CODE (XEXP (mem
, 0)) == POST_DEC
2137 || GET_CODE (XEXP (mem
, 0)) == POST_INC
2138 || GET_CODE (XEXP (mem
, 0)) == POST_MODIFY
)
2139 && GET_MODE (XEXP (mem
, 0)) == GET_MODE (r
)
2140 && rtx_equal_p (XEXP (XEXP (mem
, 0), 0), XEXP (r
, 0)))
2147 while (GET_CODE (r
) == SUBREG
2148 || GET_CODE (r
) == STRICT_LOW_PART
2149 || GET_CODE (r
) == ZERO_EXTRACT
)
2152 if (GET_CODE (r
) == REG
)
2154 int regno
= REGNO (r
);
2157 if (REGNO_REG_SET_P (pbi
->reg_live
, regno
))
2160 /* If this is a hard register, verify that subsequent
2161 words are not needed. */
2162 if (regno
< FIRST_PSEUDO_REGISTER
)
2164 int n
= hard_regno_nregs
[regno
][GET_MODE (r
)];
2167 if (REGNO_REG_SET_P (pbi
->reg_live
, regno
+n
))
2171 /* Don't delete insns to set global regs. */
2172 if (regno
< FIRST_PSEUDO_REGISTER
&& global_regs
[regno
])
2175 /* Make sure insns to set the stack pointer aren't deleted. */
2176 if (regno
== STACK_POINTER_REGNUM
)
2179 /* ??? These bits might be redundant with the force live bits
2180 in calculate_global_regs_live. We would delete from
2181 sequential sets; whether this actually affects real code
2182 for anything but the stack pointer I don't know. */
2183 /* Make sure insns to set the frame pointer aren't deleted. */
2184 if (regno
== FRAME_POINTER_REGNUM
2185 && (! reload_completed
|| frame_pointer_needed
))
2187 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
2188 if (regno
== HARD_FRAME_POINTER_REGNUM
2189 && (! reload_completed
|| frame_pointer_needed
))
2193 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
2194 /* Make sure insns to set arg pointer are never deleted
2195 (if the arg pointer isn't fixed, there will be a USE
2196 for it, so we can treat it normally). */
2197 if (regno
== ARG_POINTER_REGNUM
&& fixed_regs
[regno
])
2201 /* Otherwise, the set is dead. */
2207 /* If performing several activities, insn is dead if each activity
2208 is individually dead. Also, CLOBBERs and USEs can be ignored; a
2209 CLOBBER or USE that's inside a PARALLEL doesn't make the insn
2211 else if (code
== PARALLEL
)
2213 int i
= XVECLEN (x
, 0);
2215 for (i
--; i
>= 0; i
--)
2216 if (GET_CODE (XVECEXP (x
, 0, i
)) != CLOBBER
2217 && GET_CODE (XVECEXP (x
, 0, i
)) != USE
2218 && ! insn_dead_p (pbi
, XVECEXP (x
, 0, i
), call_ok
, NULL_RTX
))
2224 /* A CLOBBER of a pseudo-register that is dead serves no purpose. That
2225 is not necessarily true for hard registers until after reload. */
2226 else if (code
== CLOBBER
)
2228 if (GET_CODE (XEXP (x
, 0)) == REG
2229 && (REGNO (XEXP (x
, 0)) >= FIRST_PSEUDO_REGISTER
2230 || reload_completed
)
2231 && ! REGNO_REG_SET_P (pbi
->reg_live
, REGNO (XEXP (x
, 0))))
2235 /* ??? A base USE is a historical relic. It ought not be needed anymore.
2236 Instances where it is still used are either (1) temporary and the USE
2237 escaped the pass, (2) cruft and the USE need not be emitted anymore,
2238 or (3) hiding bugs elsewhere that are not properly representing data
2244 /* If INSN is the last insn in a libcall, and assuming INSN is dead,
2245 return 1 if the entire library call is dead.
2246 This is true if INSN copies a register (hard or pseudo)
2247 and if the hard return reg of the call insn is dead.
2248 (The caller should have tested the destination of the SET inside
2249 INSN already for death.)
2251 If this insn doesn't just copy a register, then we don't
2252 have an ordinary libcall. In that case, cse could not have
2253 managed to substitute the source for the dest later on,
2254 so we can assume the libcall is dead.
2256 PBI is the block info giving pseudoregs live before this insn.
2257 NOTE is the REG_RETVAL note of the insn. */
2260 libcall_dead_p (struct propagate_block_info
*pbi
, rtx note
, rtx insn
)
2262 rtx x
= single_set (insn
);
2266 rtx r
= SET_SRC (x
);
2268 if (GET_CODE (r
) == REG
)
2270 rtx call
= XEXP (note
, 0);
2274 /* Find the call insn. */
2275 while (call
!= insn
&& GET_CODE (call
) != CALL_INSN
)
2276 call
= NEXT_INSN (call
);
2278 /* If there is none, do nothing special,
2279 since ordinary death handling can understand these insns. */
2283 /* See if the hard reg holding the value is dead.
2284 If this is a PARALLEL, find the call within it. */
2285 call_pat
= PATTERN (call
);
2286 if (GET_CODE (call_pat
) == PARALLEL
)
2288 for (i
= XVECLEN (call_pat
, 0) - 1; i
>= 0; i
--)
2289 if (GET_CODE (XVECEXP (call_pat
, 0, i
)) == SET
2290 && GET_CODE (SET_SRC (XVECEXP (call_pat
, 0, i
))) == CALL
)
2293 /* This may be a library call that is returning a value
2294 via invisible pointer. Do nothing special, since
2295 ordinary death handling can understand these insns. */
2299 call_pat
= XVECEXP (call_pat
, 0, i
);
2302 return insn_dead_p (pbi
, call_pat
, 1, REG_NOTES (call
));
2308 /* 1 if register REGNO was alive at a place where `setjmp' was called
2309 and was set more than once or is an argument.
2310 Such regs may be clobbered by `longjmp'. */
2313 regno_clobbered_at_setjmp (int regno
)
2315 if (n_basic_blocks
== 0)
2318 return ((REG_N_SETS (regno
) > 1
2319 || REGNO_REG_SET_P (ENTRY_BLOCK_PTR
->global_live_at_end
, regno
))
2320 && REGNO_REG_SET_P (regs_live_at_setjmp
, regno
));
2323 /* Add MEM to PBI->MEM_SET_LIST. MEM should be canonical. Respect the
2324 maximal list size; look for overlaps in mode and select the largest. */
2326 add_to_mem_set_list (struct propagate_block_info
*pbi
, rtx mem
)
2330 /* We don't know how large a BLKmode store is, so we must not
2331 take them into consideration. */
2332 if (GET_MODE (mem
) == BLKmode
)
2335 for (i
= pbi
->mem_set_list
; i
; i
= XEXP (i
, 1))
2337 rtx e
= XEXP (i
, 0);
2338 if (rtx_equal_p (XEXP (mem
, 0), XEXP (e
, 0)))
2340 if (GET_MODE_SIZE (GET_MODE (mem
)) > GET_MODE_SIZE (GET_MODE (e
)))
2343 /* If we must store a copy of the mem, we can just modify
2344 the mode of the stored copy. */
2345 if (pbi
->flags
& PROP_AUTOINC
)
2346 PUT_MODE (e
, GET_MODE (mem
));
2355 if (pbi
->mem_set_list_len
< MAX_MEM_SET_LIST_LEN
)
2358 /* Store a copy of mem, otherwise the address may be
2359 scrogged by find_auto_inc. */
2360 if (pbi
->flags
& PROP_AUTOINC
)
2361 mem
= shallow_copy_rtx (mem
);
2363 pbi
->mem_set_list
= alloc_EXPR_LIST (0, mem
, pbi
->mem_set_list
);
2364 pbi
->mem_set_list_len
++;
2368 /* INSN references memory, possibly using autoincrement addressing modes.
2369 Find any entries on the mem_set_list that need to be invalidated due
2370 to an address change. */
2373 invalidate_mems_from_autoinc (rtx
*px
, void *data
)
2376 struct propagate_block_info
*pbi
= data
;
2378 if (GET_RTX_CLASS (GET_CODE (x
)) == RTX_AUTOINC
)
2380 invalidate_mems_from_set (pbi
, XEXP (x
, 0));
2387 /* EXP is a REG. Remove any dependent entries from pbi->mem_set_list. */
2390 invalidate_mems_from_set (struct propagate_block_info
*pbi
, rtx exp
)
2392 rtx temp
= pbi
->mem_set_list
;
2393 rtx prev
= NULL_RTX
;
2398 next
= XEXP (temp
, 1);
2399 if (reg_overlap_mentioned_p (exp
, XEXP (temp
, 0)))
2401 /* Splice this entry out of the list. */
2403 XEXP (prev
, 1) = next
;
2405 pbi
->mem_set_list
= next
;
2406 free_EXPR_LIST_node (temp
);
2407 pbi
->mem_set_list_len
--;
2415 /* Process the registers that are set within X. Their bits are set to
2416 1 in the regset DEAD, because they are dead prior to this insn.
2418 If INSN is nonzero, it is the insn being processed.
2420 FLAGS is the set of operations to perform. */
2423 mark_set_regs (struct propagate_block_info
*pbi
, rtx x
, rtx insn
)
2425 rtx cond
= NULL_RTX
;
2428 int flags
= pbi
->flags
;
2431 for (link
= REG_NOTES (insn
); link
; link
= XEXP (link
, 1))
2433 if (REG_NOTE_KIND (link
) == REG_INC
)
2434 mark_set_1 (pbi
, SET
, XEXP (link
, 0),
2435 (GET_CODE (x
) == COND_EXEC
2436 ? COND_EXEC_TEST (x
) : NULL_RTX
),
2440 switch (code
= GET_CODE (x
))
2443 if (GET_CODE (XEXP (x
, 1)) == ASM_OPERANDS
)
2444 flags
|= PROP_ASM_SCAN
;
2447 mark_set_1 (pbi
, code
, SET_DEST (x
), cond
, insn
, flags
);
2451 cond
= COND_EXEC_TEST (x
);
2452 x
= COND_EXEC_CODE (x
);
2459 /* We must scan forwards. If we have an asm, we need to set
2460 the PROP_ASM_SCAN flag before scanning the clobbers. */
2461 for (i
= 0; i
< XVECLEN (x
, 0); i
++)
2463 rtx sub
= XVECEXP (x
, 0, i
);
2464 switch (code
= GET_CODE (sub
))
2467 if (cond
!= NULL_RTX
)
2470 cond
= COND_EXEC_TEST (sub
);
2471 sub
= COND_EXEC_CODE (sub
);
2472 if (GET_CODE (sub
) == SET
)
2474 if (GET_CODE (sub
) == CLOBBER
)
2480 if (GET_CODE (XEXP (sub
, 1)) == ASM_OPERANDS
)
2481 flags
|= PROP_ASM_SCAN
;
2485 mark_set_1 (pbi
, code
, SET_DEST (sub
), cond
, insn
, flags
);
2489 flags
|= PROP_ASM_SCAN
;
2504 /* Process a single set, which appears in INSN. REG (which may not
2505 actually be a REG, it may also be a SUBREG, PARALLEL, etc.) is
2506 being set using the CODE (which may be SET, CLOBBER, or COND_EXEC).
2507 If the set is conditional (because it appear in a COND_EXEC), COND
2508 will be the condition. */
2511 mark_set_1 (struct propagate_block_info
*pbi
, enum rtx_code code
, rtx reg
, rtx cond
, rtx insn
, int flags
)
2513 int regno_first
= -1, regno_last
= -1;
2514 unsigned long not_dead
= 0;
2517 /* Modifying just one hardware register of a multi-reg value or just a
2518 byte field of a register does not mean the value from before this insn
2519 is now dead. Of course, if it was dead after it's unused now. */
2521 switch (GET_CODE (reg
))
2524 /* Some targets place small structures in registers for return values of
2525 functions. We have to detect this case specially here to get correct
2526 flow information. */
2527 for (i
= XVECLEN (reg
, 0) - 1; i
>= 0; i
--)
2528 if (XEXP (XVECEXP (reg
, 0, i
), 0) != 0)
2529 mark_set_1 (pbi
, code
, XEXP (XVECEXP (reg
, 0, i
), 0), cond
, insn
,
2535 case STRICT_LOW_PART
:
2536 /* ??? Assumes STRICT_LOW_PART not used on multi-word registers. */
2538 reg
= XEXP (reg
, 0);
2539 while (GET_CODE (reg
) == SUBREG
2540 || GET_CODE (reg
) == ZERO_EXTRACT
2541 || GET_CODE (reg
) == SIGN_EXTRACT
2542 || GET_CODE (reg
) == STRICT_LOW_PART
);
2543 if (GET_CODE (reg
) == MEM
)
2545 not_dead
= (unsigned long) REGNO_REG_SET_P (pbi
->reg_live
, REGNO (reg
));
2549 regno_last
= regno_first
= REGNO (reg
);
2550 if (regno_first
< FIRST_PSEUDO_REGISTER
)
2551 regno_last
+= hard_regno_nregs
[regno_first
][GET_MODE (reg
)] - 1;
2555 if (GET_CODE (SUBREG_REG (reg
)) == REG
)
2557 enum machine_mode outer_mode
= GET_MODE (reg
);
2558 enum machine_mode inner_mode
= GET_MODE (SUBREG_REG (reg
));
2560 /* Identify the range of registers affected. This is moderately
2561 tricky for hard registers. See alter_subreg. */
2563 regno_last
= regno_first
= REGNO (SUBREG_REG (reg
));
2564 if (regno_first
< FIRST_PSEUDO_REGISTER
)
2566 regno_first
+= subreg_regno_offset (regno_first
, inner_mode
,
2569 regno_last
= (regno_first
2570 + hard_regno_nregs
[regno_first
][outer_mode
] - 1);
2572 /* Since we've just adjusted the register number ranges, make
2573 sure REG matches. Otherwise some_was_live will be clear
2574 when it shouldn't have been, and we'll create incorrect
2575 REG_UNUSED notes. */
2576 reg
= gen_rtx_REG (outer_mode
, regno_first
);
2580 /* If the number of words in the subreg is less than the number
2581 of words in the full register, we have a well-defined partial
2582 set. Otherwise the high bits are undefined.
2584 This is only really applicable to pseudos, since we just took
2585 care of multi-word hard registers. */
2586 if (((GET_MODE_SIZE (outer_mode
)
2587 + UNITS_PER_WORD
- 1) / UNITS_PER_WORD
)
2588 < ((GET_MODE_SIZE (inner_mode
)
2589 + UNITS_PER_WORD
- 1) / UNITS_PER_WORD
))
2590 not_dead
= (unsigned long) REGNO_REG_SET_P (pbi
->reg_live
,
2593 reg
= SUBREG_REG (reg
);
2597 reg
= SUBREG_REG (reg
);
2604 /* If this set is a MEM, then it kills any aliased writes.
2605 If this set is a REG, then it kills any MEMs which use the reg. */
2606 if (optimize
&& (flags
& PROP_SCAN_DEAD_STORES
))
2608 if (GET_CODE (reg
) == REG
)
2609 invalidate_mems_from_set (pbi
, reg
);
2611 /* If the memory reference had embedded side effects (autoincrement
2612 address modes. Then we may need to kill some entries on the
2614 if (insn
&& GET_CODE (reg
) == MEM
)
2615 for_each_rtx (&PATTERN (insn
), invalidate_mems_from_autoinc
, pbi
);
2617 if (GET_CODE (reg
) == MEM
&& ! side_effects_p (reg
)
2618 /* ??? With more effort we could track conditional memory life. */
2620 add_to_mem_set_list (pbi
, canon_rtx (reg
));
2623 if (GET_CODE (reg
) == REG
2624 && ! (regno_first
== FRAME_POINTER_REGNUM
2625 && (! reload_completed
|| frame_pointer_needed
))
2626 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
2627 && ! (regno_first
== HARD_FRAME_POINTER_REGNUM
2628 && (! reload_completed
|| frame_pointer_needed
))
2630 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
2631 && ! (regno_first
== ARG_POINTER_REGNUM
&& fixed_regs
[regno_first
])
2635 int some_was_live
= 0, some_was_dead
= 0;
2637 for (i
= regno_first
; i
<= regno_last
; ++i
)
2639 int needed_regno
= REGNO_REG_SET_P (pbi
->reg_live
, i
);
2642 /* Order of the set operation matters here since both
2643 sets may be the same. */
2644 CLEAR_REGNO_REG_SET (pbi
->cond_local_set
, i
);
2645 if (cond
!= NULL_RTX
2646 && ! REGNO_REG_SET_P (pbi
->local_set
, i
))
2647 SET_REGNO_REG_SET (pbi
->cond_local_set
, i
);
2649 SET_REGNO_REG_SET (pbi
->local_set
, i
);
2651 if (code
!= CLOBBER
)
2652 SET_REGNO_REG_SET (pbi
->new_set
, i
);
2654 some_was_live
|= needed_regno
;
2655 some_was_dead
|= ! needed_regno
;
2658 #ifdef HAVE_conditional_execution
2659 /* Consider conditional death in deciding that the register needs
2661 if (some_was_live
&& ! not_dead
2662 /* The stack pointer is never dead. Well, not strictly true,
2663 but it's very difficult to tell from here. Hopefully
2664 combine_stack_adjustments will fix up the most egregious
2666 && regno_first
!= STACK_POINTER_REGNUM
)
2668 for (i
= regno_first
; i
<= regno_last
; ++i
)
2669 if (! mark_regno_cond_dead (pbi
, i
, cond
))
2670 not_dead
|= ((unsigned long) 1) << (i
- regno_first
);
2674 /* Additional data to record if this is the final pass. */
2675 if (flags
& (PROP_LOG_LINKS
| PROP_REG_INFO
2676 | PROP_DEATH_NOTES
| PROP_AUTOINC
))
2679 int blocknum
= pbi
->bb
->index
;
2682 if (flags
& (PROP_LOG_LINKS
| PROP_AUTOINC
))
2684 y
= pbi
->reg_next_use
[regno_first
];
2686 /* The next use is no longer next, since a store intervenes. */
2687 for (i
= regno_first
; i
<= regno_last
; ++i
)
2688 pbi
->reg_next_use
[i
] = 0;
2691 if (flags
& PROP_REG_INFO
)
2693 for (i
= regno_first
; i
<= regno_last
; ++i
)
2695 /* Count (weighted) references, stores, etc. This counts a
2696 register twice if it is modified, but that is correct. */
2697 REG_N_SETS (i
) += 1;
2698 REG_N_REFS (i
) += 1;
2699 REG_FREQ (i
) += REG_FREQ_FROM_BB (pbi
->bb
);
2701 /* The insns where a reg is live are normally counted
2702 elsewhere, but we want the count to include the insn
2703 where the reg is set, and the normal counting mechanism
2704 would not count it. */
2705 REG_LIVE_LENGTH (i
) += 1;
2708 /* If this is a hard reg, record this function uses the reg. */
2709 if (regno_first
< FIRST_PSEUDO_REGISTER
)
2711 for (i
= regno_first
; i
<= regno_last
; i
++)
2712 regs_ever_live
[i
] = 1;
2713 if (flags
& PROP_ASM_SCAN
)
2714 for (i
= regno_first
; i
<= regno_last
; i
++)
2715 regs_asm_clobbered
[i
] = 1;
2719 /* Keep track of which basic blocks each reg appears in. */
2720 if (REG_BASIC_BLOCK (regno_first
) == REG_BLOCK_UNKNOWN
)
2721 REG_BASIC_BLOCK (regno_first
) = blocknum
;
2722 else if (REG_BASIC_BLOCK (regno_first
) != blocknum
)
2723 REG_BASIC_BLOCK (regno_first
) = REG_BLOCK_GLOBAL
;
2727 if (! some_was_dead
)
2729 if (flags
& PROP_LOG_LINKS
)
2731 /* Make a logical link from the next following insn
2732 that uses this register, back to this insn.
2733 The following insns have already been processed.
2735 We don't build a LOG_LINK for hard registers containing
2736 in ASM_OPERANDs. If these registers get replaced,
2737 we might wind up changing the semantics of the insn,
2738 even if reload can make what appear to be valid
2741 We don't build a LOG_LINK for global registers to
2742 or from a function call. We don't want to let
2743 combine think that it knows what is going on with
2744 global registers. */
2745 if (y
&& (BLOCK_NUM (y
) == blocknum
)
2746 && (regno_first
>= FIRST_PSEUDO_REGISTER
2747 || (asm_noperands (PATTERN (y
)) < 0
2748 && ! ((GET_CODE (insn
) == CALL_INSN
2749 || GET_CODE (y
) == CALL_INSN
)
2750 && global_regs
[regno_first
]))))
2751 LOG_LINKS (y
) = alloc_INSN_LIST (insn
, LOG_LINKS (y
));
2756 else if (! some_was_live
)
2758 if (flags
& PROP_REG_INFO
)
2759 REG_N_DEATHS (regno_first
) += 1;
2761 if (flags
& PROP_DEATH_NOTES
)
2763 /* Note that dead stores have already been deleted
2764 when possible. If we get here, we have found a
2765 dead store that cannot be eliminated (because the
2766 same insn does something useful). Indicate this
2767 by marking the reg being set as dying here. */
2769 = alloc_EXPR_LIST (REG_UNUSED
, reg
, REG_NOTES (insn
));
2774 if (flags
& PROP_DEATH_NOTES
)
2776 /* This is a case where we have a multi-word hard register
2777 and some, but not all, of the words of the register are
2778 needed in subsequent insns. Write REG_UNUSED notes
2779 for those parts that were not needed. This case should
2782 for (i
= regno_first
; i
<= regno_last
; ++i
)
2783 if (! REGNO_REG_SET_P (pbi
->reg_live
, i
))
2785 = alloc_EXPR_LIST (REG_UNUSED
,
2792 /* Mark the register as being dead. */
2794 /* The stack pointer is never dead. Well, not strictly true,
2795 but it's very difficult to tell from here. Hopefully
2796 combine_stack_adjustments will fix up the most egregious
2798 && regno_first
!= STACK_POINTER_REGNUM
)
2800 for (i
= regno_first
; i
<= regno_last
; ++i
)
2801 if (!(not_dead
& (((unsigned long) 1) << (i
- regno_first
))))
2803 if ((pbi
->flags
& PROP_REG_INFO
)
2804 && REGNO_REG_SET_P (pbi
->reg_live
, i
))
2806 REG_LIVE_LENGTH (i
) += pbi
->insn_num
- reg_deaths
[i
];
2809 CLEAR_REGNO_REG_SET (pbi
->reg_live
, i
);
2813 else if (GET_CODE (reg
) == REG
)
2815 if (flags
& (PROP_LOG_LINKS
| PROP_AUTOINC
))
2816 pbi
->reg_next_use
[regno_first
] = 0;
2818 if ((flags
& PROP_REG_INFO
) != 0
2819 && (flags
& PROP_ASM_SCAN
) != 0
2820 && regno_first
< FIRST_PSEUDO_REGISTER
)
2822 for (i
= regno_first
; i
<= regno_last
; i
++)
2823 regs_asm_clobbered
[i
] = 1;
2827 /* If this is the last pass and this is a SCRATCH, show it will be dying
2828 here and count it. */
2829 else if (GET_CODE (reg
) == SCRATCH
)
2831 if (flags
& PROP_DEATH_NOTES
)
2833 = alloc_EXPR_LIST (REG_UNUSED
, reg
, REG_NOTES (insn
));
2837 #ifdef HAVE_conditional_execution
2838 /* Mark REGNO conditionally dead.
2839 Return true if the register is now unconditionally dead. */
2842 mark_regno_cond_dead (struct propagate_block_info
*pbi
, int regno
, rtx cond
)
2844 /* If this is a store to a predicate register, the value of the
2845 predicate is changing, we don't know that the predicate as seen
2846 before is the same as that seen after. Flush all dependent
2847 conditions from reg_cond_dead. This will make all such
2848 conditionally live registers unconditionally live. */
2849 if (REGNO_REG_SET_P (pbi
->reg_cond_reg
, regno
))
2850 flush_reg_cond_reg (pbi
, regno
);
2852 /* If this is an unconditional store, remove any conditional
2853 life that may have existed. */
2854 if (cond
== NULL_RTX
)
2855 splay_tree_remove (pbi
->reg_cond_dead
, regno
);
2858 splay_tree_node node
;
2859 struct reg_cond_life_info
*rcli
;
2862 /* Otherwise this is a conditional set. Record that fact.
2863 It may have been conditionally used, or there may be a
2864 subsequent set with a complimentary condition. */
2866 node
= splay_tree_lookup (pbi
->reg_cond_dead
, regno
);
2869 /* The register was unconditionally live previously.
2870 Record the current condition as the condition under
2871 which it is dead. */
2872 rcli
= xmalloc (sizeof (*rcli
));
2873 rcli
->condition
= cond
;
2874 rcli
->stores
= cond
;
2875 rcli
->orig_condition
= const0_rtx
;
2876 splay_tree_insert (pbi
->reg_cond_dead
, regno
,
2877 (splay_tree_value
) rcli
);
2879 SET_REGNO_REG_SET (pbi
->reg_cond_reg
, REGNO (XEXP (cond
, 0)));
2881 /* Not unconditionally dead. */
2886 /* The register was conditionally live previously.
2887 Add the new condition to the old. */
2888 rcli
= (struct reg_cond_life_info
*) node
->value
;
2889 ncond
= rcli
->condition
;
2890 ncond
= ior_reg_cond (ncond
, cond
, 1);
2891 if (rcli
->stores
== const0_rtx
)
2892 rcli
->stores
= cond
;
2893 else if (rcli
->stores
!= const1_rtx
)
2894 rcli
->stores
= ior_reg_cond (rcli
->stores
, cond
, 1);
2896 /* If the register is now unconditionally dead, remove the entry
2897 in the splay_tree. A register is unconditionally dead if the
2898 dead condition ncond is true. A register is also unconditionally
2899 dead if the sum of all conditional stores is an unconditional
2900 store (stores is true), and the dead condition is identically the
2901 same as the original dead condition initialized at the end of
2902 the block. This is a pointer compare, not an rtx_equal_p
2904 if (ncond
== const1_rtx
2905 || (ncond
== rcli
->orig_condition
&& rcli
->stores
== const1_rtx
))
2906 splay_tree_remove (pbi
->reg_cond_dead
, regno
);
2909 rcli
->condition
= ncond
;
2911 SET_REGNO_REG_SET (pbi
->reg_cond_reg
, REGNO (XEXP (cond
, 0)));
2913 /* Not unconditionally dead. */
2922 /* Called from splay_tree_delete for pbi->reg_cond_life. */
2925 free_reg_cond_life_info (splay_tree_value value
)
2927 struct reg_cond_life_info
*rcli
= (struct reg_cond_life_info
*) value
;
2931 /* Helper function for flush_reg_cond_reg. */
2934 flush_reg_cond_reg_1 (splay_tree_node node
, void *data
)
2936 struct reg_cond_life_info
*rcli
;
2937 int *xdata
= (int *) data
;
2938 unsigned int regno
= xdata
[0];
2940 /* Don't need to search if last flushed value was farther on in
2941 the in-order traversal. */
2942 if (xdata
[1] >= (int) node
->key
)
2945 /* Splice out portions of the expression that refer to regno. */
2946 rcli
= (struct reg_cond_life_info
*) node
->value
;
2947 rcli
->condition
= elim_reg_cond (rcli
->condition
, regno
);
2948 if (rcli
->stores
!= const0_rtx
&& rcli
->stores
!= const1_rtx
)
2949 rcli
->stores
= elim_reg_cond (rcli
->stores
, regno
);
2951 /* If the entire condition is now false, signal the node to be removed. */
2952 if (rcli
->condition
== const0_rtx
)
2954 xdata
[1] = node
->key
;
2957 else if (rcli
->condition
== const1_rtx
)
2963 /* Flush all (sub) expressions referring to REGNO from REG_COND_LIVE. */
2966 flush_reg_cond_reg (struct propagate_block_info
*pbi
, int regno
)
2972 while (splay_tree_foreach (pbi
->reg_cond_dead
,
2973 flush_reg_cond_reg_1
, pair
) == -1)
2974 splay_tree_remove (pbi
->reg_cond_dead
, pair
[1]);
2976 CLEAR_REGNO_REG_SET (pbi
->reg_cond_reg
, regno
);
2979 /* Logical arithmetic on predicate conditions. IOR, NOT and AND.
2980 For ior/and, the ADD flag determines whether we want to add the new
2981 condition X to the old one unconditionally. If it is zero, we will
2982 only return a new expression if X allows us to simplify part of
2983 OLD, otherwise we return NULL to the caller.
2984 If ADD is nonzero, we will return a new condition in all cases. The
2985 toplevel caller of one of these functions should always pass 1 for
2989 ior_reg_cond (rtx old
, rtx x
, int add
)
2993 if (COMPARISON_P (old
))
2995 if (COMPARISON_P (x
)
2996 && REVERSE_CONDEXEC_PREDICATES_P (GET_CODE (x
), GET_CODE (old
))
2997 && REGNO (XEXP (x
, 0)) == REGNO (XEXP (old
, 0)))
2999 if (GET_CODE (x
) == GET_CODE (old
)
3000 && REGNO (XEXP (x
, 0)) == REGNO (XEXP (old
, 0)))
3004 return gen_rtx_IOR (0, old
, x
);
3007 switch (GET_CODE (old
))
3010 op0
= ior_reg_cond (XEXP (old
, 0), x
, 0);
3011 op1
= ior_reg_cond (XEXP (old
, 1), x
, 0);
3012 if (op0
!= NULL
|| op1
!= NULL
)
3014 if (op0
== const0_rtx
)
3015 return op1
? op1
: gen_rtx_IOR (0, XEXP (old
, 1), x
);
3016 if (op1
== const0_rtx
)
3017 return op0
? op0
: gen_rtx_IOR (0, XEXP (old
, 0), x
);
3018 if (op0
== const1_rtx
|| op1
== const1_rtx
)
3021 op0
= gen_rtx_IOR (0, XEXP (old
, 0), x
);
3022 else if (rtx_equal_p (x
, op0
))
3023 /* (x | A) | x ~ (x | A). */
3026 op1
= gen_rtx_IOR (0, XEXP (old
, 1), x
);
3027 else if (rtx_equal_p (x
, op1
))
3028 /* (A | x) | x ~ (A | x). */
3030 return gen_rtx_IOR (0, op0
, op1
);
3034 return gen_rtx_IOR (0, old
, x
);
3037 op0
= ior_reg_cond (XEXP (old
, 0), x
, 0);
3038 op1
= ior_reg_cond (XEXP (old
, 1), x
, 0);
3039 if (op0
!= NULL
|| op1
!= NULL
)
3041 if (op0
== const1_rtx
)
3042 return op1
? op1
: gen_rtx_IOR (0, XEXP (old
, 1), x
);
3043 if (op1
== const1_rtx
)
3044 return op0
? op0
: gen_rtx_IOR (0, XEXP (old
, 0), x
);
3045 if (op0
== const0_rtx
|| op1
== const0_rtx
)
3048 op0
= gen_rtx_IOR (0, XEXP (old
, 0), x
);
3049 else if (rtx_equal_p (x
, op0
))
3050 /* (x & A) | x ~ x. */
3053 op1
= gen_rtx_IOR (0, XEXP (old
, 1), x
);
3054 else if (rtx_equal_p (x
, op1
))
3055 /* (A & x) | x ~ x. */
3057 return gen_rtx_AND (0, op0
, op1
);
3061 return gen_rtx_IOR (0, old
, x
);
3064 op0
= and_reg_cond (XEXP (old
, 0), not_reg_cond (x
), 0);
3066 return not_reg_cond (op0
);
3069 return gen_rtx_IOR (0, old
, x
);
3077 not_reg_cond (rtx x
)
3079 enum rtx_code x_code
;
3081 if (x
== const0_rtx
)
3083 else if (x
== const1_rtx
)
3085 x_code
= GET_CODE (x
);
3088 if (COMPARISON_P (x
)
3089 && GET_CODE (XEXP (x
, 0)) == REG
)
3091 if (XEXP (x
, 1) != const0_rtx
)
3094 return gen_rtx_fmt_ee (reverse_condition (x_code
),
3095 VOIDmode
, XEXP (x
, 0), const0_rtx
);
3097 return gen_rtx_NOT (0, x
);
3101 and_reg_cond (rtx old
, rtx x
, int add
)
3105 if (COMPARISON_P (old
))
3107 if (COMPARISON_P (x
)
3108 && GET_CODE (x
) == reverse_condition (GET_CODE (old
))
3109 && REGNO (XEXP (x
, 0)) == REGNO (XEXP (old
, 0)))
3111 if (GET_CODE (x
) == GET_CODE (old
)
3112 && REGNO (XEXP (x
, 0)) == REGNO (XEXP (old
, 0)))
3116 return gen_rtx_AND (0, old
, x
);
3119 switch (GET_CODE (old
))
3122 op0
= and_reg_cond (XEXP (old
, 0), x
, 0);
3123 op1
= and_reg_cond (XEXP (old
, 1), x
, 0);
3124 if (op0
!= NULL
|| op1
!= NULL
)
3126 if (op0
== const0_rtx
)
3127 return op1
? op1
: gen_rtx_AND (0, XEXP (old
, 1), x
);
3128 if (op1
== const0_rtx
)
3129 return op0
? op0
: gen_rtx_AND (0, XEXP (old
, 0), x
);
3130 if (op0
== const1_rtx
|| op1
== const1_rtx
)
3133 op0
= gen_rtx_AND (0, XEXP (old
, 0), x
);
3134 else if (rtx_equal_p (x
, op0
))
3135 /* (x | A) & x ~ x. */
3138 op1
= gen_rtx_AND (0, XEXP (old
, 1), x
);
3139 else if (rtx_equal_p (x
, op1
))
3140 /* (A | x) & x ~ x. */
3142 return gen_rtx_IOR (0, op0
, op1
);
3146 return gen_rtx_AND (0, old
, x
);
3149 op0
= and_reg_cond (XEXP (old
, 0), x
, 0);
3150 op1
= and_reg_cond (XEXP (old
, 1), x
, 0);
3151 if (op0
!= NULL
|| op1
!= NULL
)
3153 if (op0
== const1_rtx
)
3154 return op1
? op1
: gen_rtx_AND (0, XEXP (old
, 1), x
);
3155 if (op1
== const1_rtx
)
3156 return op0
? op0
: gen_rtx_AND (0, XEXP (old
, 0), x
);
3157 if (op0
== const0_rtx
|| op1
== const0_rtx
)
3160 op0
= gen_rtx_AND (0, XEXP (old
, 0), x
);
3161 else if (rtx_equal_p (x
, op0
))
3162 /* (x & A) & x ~ (x & A). */
3165 op1
= gen_rtx_AND (0, XEXP (old
, 1), x
);
3166 else if (rtx_equal_p (x
, op1
))
3167 /* (A & x) & x ~ (A & x). */
3169 return gen_rtx_AND (0, op0
, op1
);
3173 return gen_rtx_AND (0, old
, x
);
3176 op0
= ior_reg_cond (XEXP (old
, 0), not_reg_cond (x
), 0);
3178 return not_reg_cond (op0
);
3181 return gen_rtx_AND (0, old
, x
);
3188 /* Given a condition X, remove references to reg REGNO and return the
3189 new condition. The removal will be done so that all conditions
3190 involving REGNO are considered to evaluate to false. This function
3191 is used when the value of REGNO changes. */
3194 elim_reg_cond (rtx x
, unsigned int regno
)
3198 if (COMPARISON_P (x
))
3200 if (REGNO (XEXP (x
, 0)) == regno
)
3205 switch (GET_CODE (x
))
3208 op0
= elim_reg_cond (XEXP (x
, 0), regno
);
3209 op1
= elim_reg_cond (XEXP (x
, 1), regno
);
3210 if (op0
== const0_rtx
|| op1
== const0_rtx
)
3212 if (op0
== const1_rtx
)
3214 if (op1
== const1_rtx
)
3216 if (op0
== XEXP (x
, 0) && op1
== XEXP (x
, 1))
3218 return gen_rtx_AND (0, op0
, op1
);
3221 op0
= elim_reg_cond (XEXP (x
, 0), regno
);
3222 op1
= elim_reg_cond (XEXP (x
, 1), regno
);
3223 if (op0
== const1_rtx
|| op1
== const1_rtx
)
3225 if (op0
== const0_rtx
)
3227 if (op1
== const0_rtx
)
3229 if (op0
== XEXP (x
, 0) && op1
== XEXP (x
, 1))
3231 return gen_rtx_IOR (0, op0
, op1
);
3234 op0
= elim_reg_cond (XEXP (x
, 0), regno
);
3235 if (op0
== const0_rtx
)
3237 if (op0
== const1_rtx
)
3239 if (op0
!= XEXP (x
, 0))
3240 return not_reg_cond (op0
);
3247 #endif /* HAVE_conditional_execution */
3251 /* Try to substitute the auto-inc expression INC as the address inside
3252 MEM which occurs in INSN. Currently, the address of MEM is an expression
3253 involving INCR_REG, and INCR is the next use of INCR_REG; it is an insn
3254 that has a single set whose source is a PLUS of INCR_REG and something
3258 attempt_auto_inc (struct propagate_block_info
*pbi
, rtx inc
, rtx insn
,
3259 rtx mem
, rtx incr
, rtx incr_reg
)
3261 int regno
= REGNO (incr_reg
);
3262 rtx set
= single_set (incr
);
3263 rtx q
= SET_DEST (set
);
3264 rtx y
= SET_SRC (set
);
3265 int opnum
= XEXP (y
, 0) == incr_reg
? 0 : 1;
3267 /* Make sure this reg appears only once in this insn. */
3268 if (count_occurrences (PATTERN (insn
), incr_reg
, 1) != 1)
3271 if (dead_or_set_p (incr
, incr_reg
)
3272 /* Mustn't autoinc an eliminable register. */
3273 && (regno
>= FIRST_PSEUDO_REGISTER
3274 || ! TEST_HARD_REG_BIT (elim_reg_set
, regno
)))
3276 /* This is the simple case. Try to make the auto-inc. If
3277 we can't, we are done. Otherwise, we will do any
3278 needed updates below. */
3279 if (! validate_change (insn
, &XEXP (mem
, 0), inc
, 0))
3282 else if (GET_CODE (q
) == REG
3283 /* PREV_INSN used here to check the semi-open interval
3285 && ! reg_used_between_p (q
, PREV_INSN (insn
), incr
)
3286 /* We must also check for sets of q as q may be
3287 a call clobbered hard register and there may
3288 be a call between PREV_INSN (insn) and incr. */
3289 && ! reg_set_between_p (q
, PREV_INSN (insn
), incr
))
3291 /* We have *p followed sometime later by q = p+size.
3292 Both p and q must be live afterward,
3293 and q is not used between INSN and its assignment.
3294 Change it to q = p, ...*q..., q = q+size.
3295 Then fall into the usual case. */
3299 emit_move_insn (q
, incr_reg
);
3300 insns
= get_insns ();
3303 /* If we can't make the auto-inc, or can't make the
3304 replacement into Y, exit. There's no point in making
3305 the change below if we can't do the auto-inc and doing
3306 so is not correct in the pre-inc case. */
3309 validate_change (insn
, &XEXP (mem
, 0), inc
, 1);
3310 validate_change (incr
, &XEXP (y
, opnum
), q
, 1);
3311 if (! apply_change_group ())
3314 /* We now know we'll be doing this change, so emit the
3315 new insn(s) and do the updates. */
3316 emit_insn_before (insns
, insn
);
3318 if (BB_HEAD (pbi
->bb
) == insn
)
3319 BB_HEAD (pbi
->bb
) = insns
;
3321 /* INCR will become a NOTE and INSN won't contain a
3322 use of INCR_REG. If a use of INCR_REG was just placed in
3323 the insn before INSN, make that the next use.
3324 Otherwise, invalidate it. */
3325 if (GET_CODE (PREV_INSN (insn
)) == INSN
3326 && GET_CODE (PATTERN (PREV_INSN (insn
))) == SET
3327 && SET_SRC (PATTERN (PREV_INSN (insn
))) == incr_reg
)
3328 pbi
->reg_next_use
[regno
] = PREV_INSN (insn
);
3330 pbi
->reg_next_use
[regno
] = 0;
3335 if ((pbi
->flags
& PROP_REG_INFO
)
3336 && !REGNO_REG_SET_P (pbi
->reg_live
, regno
))
3337 reg_deaths
[regno
] = pbi
->insn_num
;
3339 /* REGNO is now used in INCR which is below INSN, but
3340 it previously wasn't live here. If we don't mark
3341 it as live, we'll put a REG_DEAD note for it
3342 on this insn, which is incorrect. */
3343 SET_REGNO_REG_SET (pbi
->reg_live
, regno
);
3345 /* If there are any calls between INSN and INCR, show
3346 that REGNO now crosses them. */
3347 for (temp
= insn
; temp
!= incr
; temp
= NEXT_INSN (temp
))
3348 if (GET_CODE (temp
) == CALL_INSN
)
3349 REG_N_CALLS_CROSSED (regno
)++;
3351 /* Invalidate alias info for Q since we just changed its value. */
3352 clear_reg_alias_info (q
);
3357 /* If we haven't returned, it means we were able to make the
3358 auto-inc, so update the status. First, record that this insn
3359 has an implicit side effect. */
3361 REG_NOTES (insn
) = alloc_EXPR_LIST (REG_INC
, incr_reg
, REG_NOTES (insn
));
3363 /* Modify the old increment-insn to simply copy
3364 the already-incremented value of our register. */
3365 if (! validate_change (incr
, &SET_SRC (set
), incr_reg
, 0))
3368 /* If that makes it a no-op (copying the register into itself) delete
3369 it so it won't appear to be a "use" and a "set" of this
3371 if (REGNO (SET_DEST (set
)) == REGNO (incr_reg
))
3373 /* If the original source was dead, it's dead now. */
3376 while ((note
= find_reg_note (incr
, REG_DEAD
, NULL_RTX
)) != NULL_RTX
)
3378 remove_note (incr
, note
);
3379 if (XEXP (note
, 0) != incr_reg
)
3381 unsigned int regno
= REGNO (XEXP (note
, 0));
3383 if ((pbi
->flags
& PROP_REG_INFO
)
3384 && REGNO_REG_SET_P (pbi
->reg_live
, regno
))
3386 REG_LIVE_LENGTH (regno
) += pbi
->insn_num
- reg_deaths
[regno
];
3387 reg_deaths
[regno
] = 0;
3389 CLEAR_REGNO_REG_SET (pbi
->reg_live
, REGNO (XEXP (note
, 0)));
3393 PUT_CODE (incr
, NOTE
);
3394 NOTE_LINE_NUMBER (incr
) = NOTE_INSN_DELETED
;
3395 NOTE_SOURCE_FILE (incr
) = 0;
3398 if (regno
>= FIRST_PSEUDO_REGISTER
)
3400 /* Count an extra reference to the reg. When a reg is
3401 incremented, spilling it is worse, so we want to make
3402 that less likely. */
3403 REG_FREQ (regno
) += REG_FREQ_FROM_BB (pbi
->bb
);
3405 /* Count the increment as a setting of the register,
3406 even though it isn't a SET in rtl. */
3407 REG_N_SETS (regno
)++;
3411 /* X is a MEM found in INSN. See if we can convert it into an auto-increment
3415 find_auto_inc (struct propagate_block_info
*pbi
, rtx x
, rtx insn
)
3417 rtx addr
= XEXP (x
, 0);
3418 HOST_WIDE_INT offset
= 0;
3419 rtx set
, y
, incr
, inc_val
;
3421 int size
= GET_MODE_SIZE (GET_MODE (x
));
3423 if (GET_CODE (insn
) == JUMP_INSN
)
3426 /* Here we detect use of an index register which might be good for
3427 postincrement, postdecrement, preincrement, or predecrement. */
3429 if (GET_CODE (addr
) == PLUS
&& GET_CODE (XEXP (addr
, 1)) == CONST_INT
)
3430 offset
= INTVAL (XEXP (addr
, 1)), addr
= XEXP (addr
, 0);
3432 if (GET_CODE (addr
) != REG
)
3435 regno
= REGNO (addr
);
3437 /* Is the next use an increment that might make auto-increment? */
3438 incr
= pbi
->reg_next_use
[regno
];
3439 if (incr
== 0 || BLOCK_NUM (incr
) != BLOCK_NUM (insn
))
3441 set
= single_set (incr
);
3442 if (set
== 0 || GET_CODE (set
) != SET
)
3446 if (GET_CODE (y
) != PLUS
)
3449 if (REG_P (XEXP (y
, 0)) && REGNO (XEXP (y
, 0)) == REGNO (addr
))
3450 inc_val
= XEXP (y
, 1);
3451 else if (REG_P (XEXP (y
, 1)) && REGNO (XEXP (y
, 1)) == REGNO (addr
))
3452 inc_val
= XEXP (y
, 0);
3456 if (GET_CODE (inc_val
) == CONST_INT
)
3458 if (HAVE_POST_INCREMENT
3459 && (INTVAL (inc_val
) == size
&& offset
== 0))
3460 attempt_auto_inc (pbi
, gen_rtx_POST_INC (Pmode
, addr
), insn
, x
,
3462 else if (HAVE_POST_DECREMENT
3463 && (INTVAL (inc_val
) == -size
&& offset
== 0))
3464 attempt_auto_inc (pbi
, gen_rtx_POST_DEC (Pmode
, addr
), insn
, x
,
3466 else if (HAVE_PRE_INCREMENT
3467 && (INTVAL (inc_val
) == size
&& offset
== size
))
3468 attempt_auto_inc (pbi
, gen_rtx_PRE_INC (Pmode
, addr
), insn
, x
,
3470 else if (HAVE_PRE_DECREMENT
3471 && (INTVAL (inc_val
) == -size
&& offset
== -size
))
3472 attempt_auto_inc (pbi
, gen_rtx_PRE_DEC (Pmode
, addr
), insn
, x
,
3474 else if (HAVE_POST_MODIFY_DISP
&& offset
== 0)
3475 attempt_auto_inc (pbi
, gen_rtx_POST_MODIFY (Pmode
, addr
,
3476 gen_rtx_PLUS (Pmode
,
3479 insn
, x
, incr
, addr
);
3480 else if (HAVE_PRE_MODIFY_DISP
&& offset
== INTVAL (inc_val
))
3481 attempt_auto_inc (pbi
, gen_rtx_PRE_MODIFY (Pmode
, addr
,
3482 gen_rtx_PLUS (Pmode
,
3485 insn
, x
, incr
, addr
);
3487 else if (GET_CODE (inc_val
) == REG
3488 && ! reg_set_between_p (inc_val
, PREV_INSN (insn
),
3492 if (HAVE_POST_MODIFY_REG
&& offset
== 0)
3493 attempt_auto_inc (pbi
, gen_rtx_POST_MODIFY (Pmode
, addr
,
3494 gen_rtx_PLUS (Pmode
,
3497 insn
, x
, incr
, addr
);
3501 #endif /* AUTO_INC_DEC */
3504 mark_used_reg (struct propagate_block_info
*pbi
, rtx reg
,
3505 rtx cond ATTRIBUTE_UNUSED
, rtx insn
)
3507 unsigned int regno_first
, regno_last
, i
;
3508 int some_was_live
, some_was_dead
, some_not_set
;
3510 regno_last
= regno_first
= REGNO (reg
);
3511 if (regno_first
< FIRST_PSEUDO_REGISTER
)
3512 regno_last
+= hard_regno_nregs
[regno_first
][GET_MODE (reg
)] - 1;
3514 /* Find out if any of this register is live after this instruction. */
3515 some_was_live
= some_was_dead
= 0;
3516 for (i
= regno_first
; i
<= regno_last
; ++i
)
3518 int needed_regno
= REGNO_REG_SET_P (pbi
->reg_live
, i
);
3519 some_was_live
|= needed_regno
;
3520 some_was_dead
|= ! needed_regno
;
3523 /* Find out if any of the register was set this insn. */
3525 for (i
= regno_first
; i
<= regno_last
; ++i
)
3526 some_not_set
|= ! REGNO_REG_SET_P (pbi
->new_set
, i
);
3528 if (pbi
->flags
& (PROP_LOG_LINKS
| PROP_AUTOINC
))
3530 /* Record where each reg is used, so when the reg is set we know
3531 the next insn that uses it. */
3532 pbi
->reg_next_use
[regno_first
] = insn
;
3535 if (pbi
->flags
& PROP_REG_INFO
)
3537 if (regno_first
< FIRST_PSEUDO_REGISTER
)
3539 /* If this is a register we are going to try to eliminate,
3540 don't mark it live here. If we are successful in
3541 eliminating it, it need not be live unless it is used for
3542 pseudos, in which case it will have been set live when it
3543 was allocated to the pseudos. If the register will not
3544 be eliminated, reload will set it live at that point.
3546 Otherwise, record that this function uses this register. */
3547 /* ??? The PPC backend tries to "eliminate" on the pic
3548 register to itself. This should be fixed. In the mean
3549 time, hack around it. */
3551 if (! (TEST_HARD_REG_BIT (elim_reg_set
, regno_first
)
3552 && (regno_first
== FRAME_POINTER_REGNUM
3553 || regno_first
== ARG_POINTER_REGNUM
)))
3554 for (i
= regno_first
; i
<= regno_last
; ++i
)
3555 regs_ever_live
[i
] = 1;
3559 /* Keep track of which basic block each reg appears in. */
3561 int blocknum
= pbi
->bb
->index
;
3562 if (REG_BASIC_BLOCK (regno_first
) == REG_BLOCK_UNKNOWN
)
3563 REG_BASIC_BLOCK (regno_first
) = blocknum
;
3564 else if (REG_BASIC_BLOCK (regno_first
) != blocknum
)
3565 REG_BASIC_BLOCK (regno_first
) = REG_BLOCK_GLOBAL
;
3567 /* Count (weighted) number of uses of each reg. */
3568 REG_FREQ (regno_first
) += REG_FREQ_FROM_BB (pbi
->bb
);
3569 REG_N_REFS (regno_first
)++;
3571 for (i
= regno_first
; i
<= regno_last
; ++i
)
3572 if (! REGNO_REG_SET_P (pbi
->reg_live
, i
))
3574 #ifdef ENABLE_CHECKING
3578 reg_deaths
[i
] = pbi
->insn_num
;
3582 /* Record and count the insns in which a reg dies. If it is used in
3583 this insn and was dead below the insn then it dies in this insn.
3584 If it was set in this insn, we do not make a REG_DEAD note;
3585 likewise if we already made such a note. */
3586 if ((pbi
->flags
& (PROP_DEATH_NOTES
| PROP_REG_INFO
))
3590 /* Check for the case where the register dying partially
3591 overlaps the register set by this insn. */
3592 if (regno_first
!= regno_last
)
3593 for (i
= regno_first
; i
<= regno_last
; ++i
)
3594 some_was_live
|= REGNO_REG_SET_P (pbi
->new_set
, i
);
3596 /* If none of the words in X is needed, make a REG_DEAD note.
3597 Otherwise, we must make partial REG_DEAD notes. */
3598 if (! some_was_live
)
3600 if ((pbi
->flags
& PROP_DEATH_NOTES
)
3601 && ! find_regno_note (insn
, REG_DEAD
, regno_first
))
3603 = alloc_EXPR_LIST (REG_DEAD
, reg
, REG_NOTES (insn
));
3605 if (pbi
->flags
& PROP_REG_INFO
)
3606 REG_N_DEATHS (regno_first
)++;
3610 /* Don't make a REG_DEAD note for a part of a register
3611 that is set in the insn. */
3612 for (i
= regno_first
; i
<= regno_last
; ++i
)
3613 if (! REGNO_REG_SET_P (pbi
->reg_live
, i
)
3614 && ! dead_or_set_regno_p (insn
, i
))
3616 = alloc_EXPR_LIST (REG_DEAD
,
3622 /* Mark the register as being live. */
3623 for (i
= regno_first
; i
<= regno_last
; ++i
)
3625 #ifdef HAVE_conditional_execution
3626 int this_was_live
= REGNO_REG_SET_P (pbi
->reg_live
, i
);
3629 SET_REGNO_REG_SET (pbi
->reg_live
, i
);
3631 #ifdef HAVE_conditional_execution
3632 /* If this is a conditional use, record that fact. If it is later
3633 conditionally set, we'll know to kill the register. */
3634 if (cond
!= NULL_RTX
)
3636 splay_tree_node node
;
3637 struct reg_cond_life_info
*rcli
;
3642 node
= splay_tree_lookup (pbi
->reg_cond_dead
, i
);
3645 /* The register was unconditionally live previously.
3646 No need to do anything. */
3650 /* The register was conditionally live previously.
3651 Subtract the new life cond from the old death cond. */
3652 rcli
= (struct reg_cond_life_info
*) node
->value
;
3653 ncond
= rcli
->condition
;
3654 ncond
= and_reg_cond (ncond
, not_reg_cond (cond
), 1);
3656 /* If the register is now unconditionally live,
3657 remove the entry in the splay_tree. */
3658 if (ncond
== const0_rtx
)
3659 splay_tree_remove (pbi
->reg_cond_dead
, i
);
3662 rcli
->condition
= ncond
;
3663 SET_REGNO_REG_SET (pbi
->reg_cond_reg
,
3664 REGNO (XEXP (cond
, 0)));
3670 /* The register was not previously live at all. Record
3671 the condition under which it is still dead. */
3672 rcli
= xmalloc (sizeof (*rcli
));
3673 rcli
->condition
= not_reg_cond (cond
);
3674 rcli
->stores
= const0_rtx
;
3675 rcli
->orig_condition
= const0_rtx
;
3676 splay_tree_insert (pbi
->reg_cond_dead
, i
,
3677 (splay_tree_value
) rcli
);
3679 SET_REGNO_REG_SET (pbi
->reg_cond_reg
, REGNO (XEXP (cond
, 0)));
3682 else if (this_was_live
)
3684 /* The register may have been conditionally live previously, but
3685 is now unconditionally live. Remove it from the conditionally
3686 dead list, so that a conditional set won't cause us to think
3688 splay_tree_remove (pbi
->reg_cond_dead
, i
);
3694 /* Scan expression X and store a 1-bit in NEW_LIVE for each reg it uses.
3695 This is done assuming the registers needed from X are those that
3696 have 1-bits in PBI->REG_LIVE.
3698 INSN is the containing instruction. If INSN is dead, this function
3702 mark_used_regs (struct propagate_block_info
*pbi
, rtx x
, rtx cond
, rtx insn
)
3706 int flags
= pbi
->flags
;
3711 code
= GET_CODE (x
);
3732 /* If we are clobbering a MEM, mark any registers inside the address
3734 if (GET_CODE (XEXP (x
, 0)) == MEM
)
3735 mark_used_regs (pbi
, XEXP (XEXP (x
, 0), 0), cond
, insn
);
3739 /* Don't bother watching stores to mems if this is not the
3740 final pass. We'll not be deleting dead stores this round. */
3741 if (optimize
&& (flags
& PROP_SCAN_DEAD_STORES
))
3743 /* Invalidate the data for the last MEM stored, but only if MEM is
3744 something that can be stored into. */
3745 if (GET_CODE (XEXP (x
, 0)) == SYMBOL_REF
3746 && CONSTANT_POOL_ADDRESS_P (XEXP (x
, 0)))
3747 /* Needn't clear the memory set list. */
3751 rtx temp
= pbi
->mem_set_list
;
3752 rtx prev
= NULL_RTX
;
3757 next
= XEXP (temp
, 1);
3758 if (unchanging_anti_dependence (XEXP (temp
, 0), x
))
3760 /* Splice temp out of the list. */
3762 XEXP (prev
, 1) = next
;
3764 pbi
->mem_set_list
= next
;
3765 free_EXPR_LIST_node (temp
);
3766 pbi
->mem_set_list_len
--;
3774 /* If the memory reference had embedded side effects (autoincrement
3775 address modes. Then we may need to kill some entries on the
3778 for_each_rtx (&PATTERN (insn
), invalidate_mems_from_autoinc
, pbi
);
3782 if (flags
& PROP_AUTOINC
)
3783 find_auto_inc (pbi
, x
, insn
);
3788 #ifdef CANNOT_CHANGE_MODE_CLASS
3789 if ((flags
& PROP_REG_INFO
)
3790 && GET_CODE (SUBREG_REG (x
)) == REG
3791 && REGNO (SUBREG_REG (x
)) >= FIRST_PSEUDO_REGISTER
)
3792 bitmap_set_bit (&subregs_of_mode
, REGNO (SUBREG_REG (x
))
3797 /* While we're here, optimize this case. */
3799 if (GET_CODE (x
) != REG
)
3804 /* See a register other than being set => mark it as needed. */
3805 mark_used_reg (pbi
, x
, cond
, insn
);
3810 rtx testreg
= SET_DEST (x
);
3813 /* If storing into MEM, don't show it as being used. But do
3814 show the address as being used. */
3815 if (GET_CODE (testreg
) == MEM
)
3818 if (flags
& PROP_AUTOINC
)
3819 find_auto_inc (pbi
, testreg
, insn
);
3821 mark_used_regs (pbi
, XEXP (testreg
, 0), cond
, insn
);
3822 mark_used_regs (pbi
, SET_SRC (x
), cond
, insn
);
3826 /* Storing in STRICT_LOW_PART is like storing in a reg
3827 in that this SET might be dead, so ignore it in TESTREG.
3828 but in some other ways it is like using the reg.
3830 Storing in a SUBREG or a bit field is like storing the entire
3831 register in that if the register's value is not used
3832 then this SET is not needed. */
3833 while (GET_CODE (testreg
) == STRICT_LOW_PART
3834 || GET_CODE (testreg
) == ZERO_EXTRACT
3835 || GET_CODE (testreg
) == SIGN_EXTRACT
3836 || GET_CODE (testreg
) == SUBREG
)
3838 #ifdef CANNOT_CHANGE_MODE_CLASS
3839 if ((flags
& PROP_REG_INFO
)
3840 && GET_CODE (testreg
) == SUBREG
3841 && GET_CODE (SUBREG_REG (testreg
)) == REG
3842 && REGNO (SUBREG_REG (testreg
)) >= FIRST_PSEUDO_REGISTER
)
3843 bitmap_set_bit (&subregs_of_mode
, REGNO (SUBREG_REG (testreg
))
3845 + GET_MODE (testreg
));
3848 /* Modifying a single register in an alternate mode
3849 does not use any of the old value. But these other
3850 ways of storing in a register do use the old value. */
3851 if (GET_CODE (testreg
) == SUBREG
3852 && !((REG_BYTES (SUBREG_REG (testreg
))
3853 + UNITS_PER_WORD
- 1) / UNITS_PER_WORD
3854 > (REG_BYTES (testreg
)
3855 + UNITS_PER_WORD
- 1) / UNITS_PER_WORD
))
3860 testreg
= XEXP (testreg
, 0);
3863 /* If this is a store into a register or group of registers,
3864 recursively scan the value being stored. */
3866 if ((GET_CODE (testreg
) == PARALLEL
3867 && GET_MODE (testreg
) == BLKmode
)
3868 || (GET_CODE (testreg
) == REG
3869 && (regno
= REGNO (testreg
),
3870 ! (regno
== FRAME_POINTER_REGNUM
3871 && (! reload_completed
|| frame_pointer_needed
)))
3872 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
3873 && ! (regno
== HARD_FRAME_POINTER_REGNUM
3874 && (! reload_completed
|| frame_pointer_needed
))
3876 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
3877 && ! (regno
== ARG_POINTER_REGNUM
&& fixed_regs
[regno
])
3882 mark_used_regs (pbi
, SET_DEST (x
), cond
, insn
);
3883 mark_used_regs (pbi
, SET_SRC (x
), cond
, insn
);
3890 case UNSPEC_VOLATILE
:
3894 /* Traditional and volatile asm instructions must be considered to use
3895 and clobber all hard registers, all pseudo-registers and all of
3896 memory. So must TRAP_IF and UNSPEC_VOLATILE operations.
3898 Consider for instance a volatile asm that changes the fpu rounding
3899 mode. An insn should not be moved across this even if it only uses
3900 pseudo-regs because it might give an incorrectly rounded result.
3902 ?!? Unfortunately, marking all hard registers as live causes massive
3903 problems for the register allocator and marking all pseudos as live
3904 creates mountains of uninitialized variable warnings.
3906 So for now, just clear the memory set list and mark any regs
3907 we can find in ASM_OPERANDS as used. */
3908 if (code
!= ASM_OPERANDS
|| MEM_VOLATILE_P (x
))
3910 free_EXPR_LIST_list (&pbi
->mem_set_list
);
3911 pbi
->mem_set_list_len
= 0;
3914 /* For all ASM_OPERANDS, we must traverse the vector of input operands.
3915 We can not just fall through here since then we would be confused
3916 by the ASM_INPUT rtx inside ASM_OPERANDS, which do not indicate
3917 traditional asms unlike their normal usage. */
3918 if (code
== ASM_OPERANDS
)
3922 for (j
= 0; j
< ASM_OPERANDS_INPUT_LENGTH (x
); j
++)
3923 mark_used_regs (pbi
, ASM_OPERANDS_INPUT (x
, j
), cond
, insn
);
3929 if (cond
!= NULL_RTX
)
3932 mark_used_regs (pbi
, COND_EXEC_TEST (x
), NULL_RTX
, insn
);
3934 cond
= COND_EXEC_TEST (x
);
3935 x
= COND_EXEC_CODE (x
);
3942 /* Recursively scan the operands of this expression. */
3945 const char * const fmt
= GET_RTX_FORMAT (code
);
3948 for (i
= GET_RTX_LENGTH (code
) - 1; i
>= 0; i
--)
3952 /* Tail recursive case: save a function call level. */
3958 mark_used_regs (pbi
, XEXP (x
, i
), cond
, insn
);
3960 else if (fmt
[i
] == 'E')
3963 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
3964 mark_used_regs (pbi
, XVECEXP (x
, i
, j
), cond
, insn
);
3973 try_pre_increment_1 (struct propagate_block_info
*pbi
, rtx insn
)
3975 /* Find the next use of this reg. If in same basic block,
3976 make it do pre-increment or pre-decrement if appropriate. */
3977 rtx x
= single_set (insn
);
3978 HOST_WIDE_INT amount
= ((GET_CODE (SET_SRC (x
)) == PLUS
? 1 : -1)
3979 * INTVAL (XEXP (SET_SRC (x
), 1)));
3980 int regno
= REGNO (SET_DEST (x
));
3981 rtx y
= pbi
->reg_next_use
[regno
];
3983 && SET_DEST (x
) != stack_pointer_rtx
3984 && BLOCK_NUM (y
) == BLOCK_NUM (insn
)
3985 /* Don't do this if the reg dies, or gets set in y; a standard addressing
3986 mode would be better. */
3987 && ! dead_or_set_p (y
, SET_DEST (x
))
3988 && try_pre_increment (y
, SET_DEST (x
), amount
))
3990 /* We have found a suitable auto-increment and already changed
3991 insn Y to do it. So flush this increment instruction. */
3992 propagate_block_delete_insn (insn
);
3994 /* Count a reference to this reg for the increment insn we are
3995 deleting. When a reg is incremented, spilling it is worse,
3996 so we want to make that less likely. */
3997 if (regno
>= FIRST_PSEUDO_REGISTER
)
3999 REG_FREQ (regno
) += REG_FREQ_FROM_BB (pbi
->bb
);
4000 REG_N_SETS (regno
)++;
4003 /* Flush any remembered memories depending on the value of
4004 the incremented register. */
4005 invalidate_mems_from_set (pbi
, SET_DEST (x
));
4012 /* Try to change INSN so that it does pre-increment or pre-decrement
4013 addressing on register REG in order to add AMOUNT to REG.
4014 AMOUNT is negative for pre-decrement.
4015 Returns 1 if the change could be made.
4016 This checks all about the validity of the result of modifying INSN. */
4019 try_pre_increment (rtx insn
, rtx reg
, HOST_WIDE_INT amount
)
4023 /* Nonzero if we can try to make a pre-increment or pre-decrement.
4024 For example, addl $4,r1; movl (r1),... can become movl +(r1),... */
4026 /* Nonzero if we can try to make a post-increment or post-decrement.
4027 For example, addl $4,r1; movl -4(r1),... can become movl (r1)+,...
4028 It is possible for both PRE_OK and POST_OK to be nonzero if the machine
4029 supports both pre-inc and post-inc, or both pre-dec and post-dec. */
4032 /* Nonzero if the opportunity actually requires post-inc or post-dec. */
4035 /* From the sign of increment, see which possibilities are conceivable
4036 on this target machine. */
4037 if (HAVE_PRE_INCREMENT
&& amount
> 0)
4039 if (HAVE_POST_INCREMENT
&& amount
> 0)
4042 if (HAVE_PRE_DECREMENT
&& amount
< 0)
4044 if (HAVE_POST_DECREMENT
&& amount
< 0)
4047 if (! (pre_ok
|| post_ok
))
4050 /* It is not safe to add a side effect to a jump insn
4051 because if the incremented register is spilled and must be reloaded
4052 there would be no way to store the incremented value back in memory. */
4054 if (GET_CODE (insn
) == JUMP_INSN
)
4059 use
= find_use_as_address (PATTERN (insn
), reg
, 0);
4060 if (post_ok
&& (use
== 0 || use
== (rtx
) (size_t) 1))
4062 use
= find_use_as_address (PATTERN (insn
), reg
, -amount
);
4066 if (use
== 0 || use
== (rtx
) (size_t) 1)
4069 if (GET_MODE_SIZE (GET_MODE (use
)) != (amount
> 0 ? amount
: - amount
))
4072 /* See if this combination of instruction and addressing mode exists. */
4073 if (! validate_change (insn
, &XEXP (use
, 0),
4074 gen_rtx_fmt_e (amount
> 0
4075 ? (do_post
? POST_INC
: PRE_INC
)
4076 : (do_post
? POST_DEC
: PRE_DEC
),
4080 /* Record that this insn now has an implicit side effect on X. */
4081 REG_NOTES (insn
) = alloc_EXPR_LIST (REG_INC
, reg
, REG_NOTES (insn
));
4085 #endif /* AUTO_INC_DEC */
4087 /* Find the place in the rtx X where REG is used as a memory address.
4088 Return the MEM rtx that so uses it.
4089 If PLUSCONST is nonzero, search instead for a memory address equivalent to
4090 (plus REG (const_int PLUSCONST)).
4092 If such an address does not appear, return 0.
4093 If REG appears more than once, or is used other than in such an address,
4097 find_use_as_address (rtx x
, rtx reg
, HOST_WIDE_INT plusconst
)
4099 enum rtx_code code
= GET_CODE (x
);
4100 const char * const fmt
= GET_RTX_FORMAT (code
);
4105 if (code
== MEM
&& XEXP (x
, 0) == reg
&& plusconst
== 0)
4108 if (code
== MEM
&& GET_CODE (XEXP (x
, 0)) == PLUS
4109 && XEXP (XEXP (x
, 0), 0) == reg
4110 && GET_CODE (XEXP (XEXP (x
, 0), 1)) == CONST_INT
4111 && INTVAL (XEXP (XEXP (x
, 0), 1)) == plusconst
)
4114 if (code
== SIGN_EXTRACT
|| code
== ZERO_EXTRACT
)
4116 /* If REG occurs inside a MEM used in a bit-field reference,
4117 that is unacceptable. */
4118 if (find_use_as_address (XEXP (x
, 0), reg
, 0) != 0)
4119 return (rtx
) (size_t) 1;
4123 return (rtx
) (size_t) 1;
4125 for (i
= GET_RTX_LENGTH (code
) - 1; i
>= 0; i
--)
4129 tem
= find_use_as_address (XEXP (x
, i
), reg
, plusconst
);
4133 return (rtx
) (size_t) 1;
4135 else if (fmt
[i
] == 'E')
4138 for (j
= XVECLEN (x
, i
) - 1; j
>= 0; j
--)
4140 tem
= find_use_as_address (XVECEXP (x
, i
, j
), reg
, plusconst
);
4144 return (rtx
) (size_t) 1;
4152 /* Write information about registers and basic blocks into FILE.
4153 This is part of making a debugging dump. */
4156 dump_regset (regset r
, FILE *outf
)
4161 fputs (" (nil)", outf
);
4165 EXECUTE_IF_SET_IN_REG_SET (r
, 0, i
,
4167 fprintf (outf
, " %d", i
);
4168 if (i
< FIRST_PSEUDO_REGISTER
)
4169 fprintf (outf
, " [%s]",
4174 /* Print a human-readable representation of R on the standard error
4175 stream. This function is designed to be used from within the
4179 debug_regset (regset r
)
4181 dump_regset (r
, stderr
);
4182 putc ('\n', stderr
);
4185 /* Recompute register set/reference counts immediately prior to register
4188 This avoids problems with set/reference counts changing to/from values
4189 which have special meanings to the register allocators.
4191 Additionally, the reference counts are the primary component used by the
4192 register allocators to prioritize pseudos for allocation to hard regs.
4193 More accurate reference counts generally lead to better register allocation.
4195 F is the first insn to be scanned.
4197 LOOP_STEP denotes how much loop_depth should be incremented per
4198 loop nesting level in order to increase the ref count more for
4199 references in a loop.
4201 It might be worthwhile to update REG_LIVE_LENGTH, REG_BASIC_BLOCK and
4202 possibly other information which is used by the register allocators. */
4205 recompute_reg_usage (rtx f ATTRIBUTE_UNUSED
, int loop_step ATTRIBUTE_UNUSED
)
4207 allocate_reg_life_data ();
4208 /* distribute_notes in combiner fails to convert some of the REG_UNUSED notes
4209 to REG_DEAD notes. This causes CHECK_DEAD_NOTES in sched1 to abort. To
4210 solve this update the DEATH_NOTES here. */
4211 update_life_info (NULL
, UPDATE_LIFE_LOCAL
, PROP_REG_INFO
| PROP_DEATH_NOTES
);
4214 /* Optionally removes all the REG_DEAD and REG_UNUSED notes from a set of
4215 blocks. If BLOCKS is NULL, assume the universal set. Returns a count
4216 of the number of registers that died. */
4219 count_or_remove_death_notes (sbitmap blocks
, int kill
)
4225 /* This used to be a loop over all the blocks with a membership test
4226 inside the loop. That can be amazingly expensive on a large CFG
4227 when only a small number of bits are set in BLOCKs (for example,
4228 the calls from the scheduler typically have very few bits set).
4230 For extra credit, someone should convert BLOCKS to a bitmap rather
4234 EXECUTE_IF_SET_IN_SBITMAP (blocks
, 0, i
,
4236 count
+= count_or_remove_death_notes_bb (BASIC_BLOCK (i
), kill
);
4243 count
+= count_or_remove_death_notes_bb (bb
, kill
);
4250 /* Optionally removes all the REG_DEAD and REG_UNUSED notes from basic
4251 block BB. Returns a count of the number of registers that died. */
4254 count_or_remove_death_notes_bb (basic_block bb
, int kill
)
4259 for (insn
= BB_HEAD (bb
); ; insn
= NEXT_INSN (insn
))
4263 rtx
*pprev
= ®_NOTES (insn
);
4268 switch (REG_NOTE_KIND (link
))
4271 if (GET_CODE (XEXP (link
, 0)) == REG
)
4273 rtx reg
= XEXP (link
, 0);
4276 if (REGNO (reg
) >= FIRST_PSEUDO_REGISTER
)
4279 n
= hard_regno_nregs
[REGNO (reg
)][GET_MODE (reg
)];
4288 rtx next
= XEXP (link
, 1);
4289 free_EXPR_LIST_node (link
);
4290 *pprev
= link
= next
;
4296 pprev
= &XEXP (link
, 1);
4303 if (insn
== BB_END (bb
))
4310 /* Clear LOG_LINKS fields of insns in a selected blocks or whole chain
4311 if blocks is NULL. */
4314 clear_log_links (sbitmap blocks
)
4321 for (insn
= get_insns (); insn
; insn
= NEXT_INSN (insn
))
4323 free_INSN_LIST_list (&LOG_LINKS (insn
));
4326 EXECUTE_IF_SET_IN_SBITMAP (blocks
, 0, i
,
4328 basic_block bb
= BASIC_BLOCK (i
);
4330 for (insn
= BB_HEAD (bb
); insn
!= NEXT_INSN (BB_END (bb
));
4331 insn
= NEXT_INSN (insn
))
4333 free_INSN_LIST_list (&LOG_LINKS (insn
));
4337 /* Given a register bitmap, turn on the bits in a HARD_REG_SET that
4338 correspond to the hard registers, if any, set in that map. This
4339 could be done far more efficiently by having all sorts of special-cases
4340 with moving single words, but probably isn't worth the trouble. */
4343 reg_set_to_hard_reg_set (HARD_REG_SET
*to
, bitmap from
)
4347 EXECUTE_IF_SET_IN_BITMAP
4350 if (i
>= FIRST_PSEUDO_REGISTER
)
4352 SET_HARD_REG_BIT (*to
, i
);