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
)
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 (REG_P (x
) && 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
);
836 && LABEL_NUSES (insn
) == LABEL_PRESERVE_P (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. */
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 (REG_P (XEXP (*ptr
, 0)) && REGNO (XEXP (*ptr
, 0)) == reg
)
1335 param
->retval
= XEXP (*ptr
, 0);
1341 if (REG_P (SUBREG_REG (*ptr
))
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
&& LABEL_P (inote
))
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
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 && REG_P (SET_DEST (x
))
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 (CALL_P (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
);
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
&& CALL_P (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 (JUMP_P (BB_END (bb
))
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);
1868 enum rtx_code inv_cond
;
1870 if (GET_CODE (reg
) == SUBREG
)
1871 reg
= SUBREG_REG (reg
);
1873 /* We can only track conditional lifetimes if the condition is
1874 in the form of a reversible comparison of a register against
1875 zero. If the condition is more complex than that, then it is
1876 safe not to record any information. */
1877 inv_cond
= reversed_comparison_code (cond_true
, BB_END (bb
));
1878 if (inv_cond
!= UNKNOWN
1880 && XEXP (cond_true
, 1) == const0_rtx
)
1883 = gen_rtx_fmt_ee (inv_cond
,
1884 GET_MODE (cond_true
), XEXP (cond_true
, 0),
1885 XEXP (cond_true
, 1));
1886 if (GET_CODE (XEXP (set_src
, 1)) == PC
)
1889 cond_false
= cond_true
;
1893 SET_REGNO_REG_SET (pbi
->reg_cond_reg
, REGNO (reg
));
1895 /* For each such register, mark it conditionally dead. */
1896 EXECUTE_IF_SET_IN_REG_SET
1899 struct reg_cond_life_info
*rcli
;
1902 rcli
= xmalloc (sizeof (*rcli
));
1904 if (REGNO_REG_SET_P (bb_true
->global_live_at_start
, i
))
1908 rcli
->condition
= cond
;
1909 rcli
->stores
= const0_rtx
;
1910 rcli
->orig_condition
= cond
;
1912 splay_tree_insert (pbi
->reg_cond_dead
, i
,
1913 (splay_tree_value
) rcli
);
1918 FREE_REG_SET (diff
);
1922 /* If this block has no successors, any stores to the frame that aren't
1923 used later in the block are dead. So make a pass over the block
1924 recording any such that are made and show them dead at the end. We do
1925 a very conservative and simple job here. */
1927 && ! (TREE_CODE (TREE_TYPE (current_function_decl
)) == FUNCTION_TYPE
1928 && (TYPE_RETURNS_STACK_DEPRESSED
1929 (TREE_TYPE (current_function_decl
))))
1930 && (flags
& PROP_SCAN_DEAD_STORES
)
1931 && (bb
->succ
== NULL
1932 || (bb
->succ
->succ_next
== NULL
1933 && bb
->succ
->dest
== EXIT_BLOCK_PTR
1934 && ! current_function_calls_eh_return
)))
1937 for (insn
= BB_END (bb
); insn
!= BB_HEAD (bb
); insn
= PREV_INSN (insn
))
1938 if (NONJUMP_INSN_P (insn
)
1939 && (set
= single_set (insn
))
1940 && MEM_P (SET_DEST (set
)))
1942 rtx mem
= SET_DEST (set
);
1943 rtx canon_mem
= canon_rtx (mem
);
1945 if (XEXP (canon_mem
, 0) == frame_pointer_rtx
1946 || (GET_CODE (XEXP (canon_mem
, 0)) == PLUS
1947 && XEXP (XEXP (canon_mem
, 0), 0) == frame_pointer_rtx
1948 && GET_CODE (XEXP (XEXP (canon_mem
, 0), 1)) == CONST_INT
))
1949 add_to_mem_set_list (pbi
, canon_mem
);
1956 /* Release a propagate_block_info struct. */
1959 free_propagate_block_info (struct propagate_block_info
*pbi
)
1961 free_EXPR_LIST_list (&pbi
->mem_set_list
);
1963 BITMAP_XFREE (pbi
->new_set
);
1965 #ifdef HAVE_conditional_execution
1966 splay_tree_delete (pbi
->reg_cond_dead
);
1967 BITMAP_XFREE (pbi
->reg_cond_reg
);
1970 if (pbi
->flags
& PROP_REG_INFO
)
1972 int num
= pbi
->insn_num
;
1975 EXECUTE_IF_SET_IN_REG_SET (pbi
->reg_live
, 0, i
,
1976 { REG_LIVE_LENGTH (i
) += num
- reg_deaths
[i
];
1980 if (pbi
->reg_next_use
)
1981 free (pbi
->reg_next_use
);
1986 /* Compute the registers live at the beginning of a basic block BB from
1987 those live at the end.
1989 When called, REG_LIVE contains those live at the end. On return, it
1990 contains those live at the beginning.
1992 LOCAL_SET, if non-null, will be set with all registers killed
1993 unconditionally by this basic block.
1994 Likewise, COND_LOCAL_SET, if non-null, will be set with all registers
1995 killed conditionally by this basic block. If there is any unconditional
1996 set of a register, then the corresponding bit will be set in LOCAL_SET
1997 and cleared in COND_LOCAL_SET.
1998 It is valid for LOCAL_SET and COND_LOCAL_SET to be the same set. In this
1999 case, the resulting set will be equal to the union of the two sets that
2000 would otherwise be computed.
2002 Return nonzero if an INSN is deleted (i.e. by dead code removal). */
2005 propagate_block (basic_block bb
, regset live
, regset local_set
,
2006 regset cond_local_set
, int flags
)
2008 struct propagate_block_info
*pbi
;
2012 pbi
= init_propagate_block_info (bb
, live
, local_set
, cond_local_set
, flags
);
2014 if (flags
& PROP_REG_INFO
)
2018 /* Process the regs live at the end of the block.
2019 Mark them as not local to any one basic block. */
2020 EXECUTE_IF_SET_IN_REG_SET (live
, 0, i
,
2021 { REG_BASIC_BLOCK (i
) = REG_BLOCK_GLOBAL
; });
2024 /* Scan the block an insn at a time from end to beginning. */
2027 for (insn
= BB_END (bb
); ; insn
= prev
)
2029 /* If this is a call to `setjmp' et al, warn if any
2030 non-volatile datum is live. */
2031 if ((flags
& PROP_REG_INFO
)
2033 && find_reg_note (insn
, REG_SETJMP
, NULL
))
2034 IOR_REG_SET (regs_live_at_setjmp
, pbi
->reg_live
);
2036 prev
= propagate_one_insn (pbi
, insn
);
2038 changed
|= insn
!= get_insns ();
2040 changed
|= NEXT_INSN (prev
) != insn
;
2042 if (insn
== BB_HEAD (bb
))
2046 free_propagate_block_info (pbi
);
2051 /* Return 1 if X (the body of an insn, or part of it) is just dead stores
2052 (SET expressions whose destinations are registers dead after the insn).
2053 NEEDED is the regset that says which regs are alive after the insn.
2055 Unless CALL_OK is nonzero, an insn is needed if it contains a CALL.
2057 If X is the entire body of an insn, NOTES contains the reg notes
2058 pertaining to the insn. */
2061 insn_dead_p (struct propagate_block_info
*pbi
, rtx x
, int call_ok
,
2062 rtx notes ATTRIBUTE_UNUSED
)
2064 enum rtx_code code
= GET_CODE (x
);
2066 /* Don't eliminate insns that may trap. */
2067 if (flag_non_call_exceptions
&& may_trap_p (x
))
2071 /* As flow is invoked after combine, we must take existing AUTO_INC
2072 expressions into account. */
2073 for (; notes
; notes
= XEXP (notes
, 1))
2075 if (REG_NOTE_KIND (notes
) == REG_INC
)
2077 int regno
= REGNO (XEXP (notes
, 0));
2079 /* Don't delete insns to set global regs. */
2080 if ((regno
< FIRST_PSEUDO_REGISTER
&& global_regs
[regno
])
2081 || REGNO_REG_SET_P (pbi
->reg_live
, regno
))
2087 /* If setting something that's a reg or part of one,
2088 see if that register's altered value will be live. */
2092 rtx r
= SET_DEST (x
);
2095 if (GET_CODE (r
) == CC0
)
2096 return ! pbi
->cc0_live
;
2099 /* A SET that is a subroutine call cannot be dead. */
2100 if (GET_CODE (SET_SRC (x
)) == CALL
)
2106 /* Don't eliminate loads from volatile memory or volatile asms. */
2107 else if (volatile_refs_p (SET_SRC (x
)))
2114 if (MEM_VOLATILE_P (r
) || GET_MODE (r
) == BLKmode
)
2117 canon_r
= canon_rtx (r
);
2119 /* Walk the set of memory locations we are currently tracking
2120 and see if one is an identical match to this memory location.
2121 If so, this memory write is dead (remember, we're walking
2122 backwards from the end of the block to the start). Since
2123 rtx_equal_p does not check the alias set or flags, we also
2124 must have the potential for them to conflict (anti_dependence). */
2125 for (temp
= pbi
->mem_set_list
; temp
!= 0; temp
= XEXP (temp
, 1))
2126 if (unchanging_anti_dependence (r
, XEXP (temp
, 0)))
2128 rtx mem
= XEXP (temp
, 0);
2130 if (rtx_equal_p (XEXP (canon_r
, 0), XEXP (mem
, 0))
2131 && (GET_MODE_SIZE (GET_MODE (canon_r
))
2132 <= GET_MODE_SIZE (GET_MODE (mem
))))
2136 /* Check if memory reference matches an auto increment. Only
2137 post increment/decrement or modify are valid. */
2138 if (GET_MODE (mem
) == GET_MODE (r
)
2139 && (GET_CODE (XEXP (mem
, 0)) == POST_DEC
2140 || GET_CODE (XEXP (mem
, 0)) == POST_INC
2141 || GET_CODE (XEXP (mem
, 0)) == POST_MODIFY
)
2142 && GET_MODE (XEXP (mem
, 0)) == GET_MODE (r
)
2143 && rtx_equal_p (XEXP (XEXP (mem
, 0), 0), XEXP (r
, 0)))
2150 while (GET_CODE (r
) == SUBREG
2151 || GET_CODE (r
) == STRICT_LOW_PART
2152 || GET_CODE (r
) == ZERO_EXTRACT
)
2157 int regno
= REGNO (r
);
2160 if (REGNO_REG_SET_P (pbi
->reg_live
, regno
))
2163 /* If this is a hard register, verify that subsequent
2164 words are not needed. */
2165 if (regno
< FIRST_PSEUDO_REGISTER
)
2167 int n
= hard_regno_nregs
[regno
][GET_MODE (r
)];
2170 if (REGNO_REG_SET_P (pbi
->reg_live
, regno
+n
))
2174 /* Don't delete insns to set global regs. */
2175 if (regno
< FIRST_PSEUDO_REGISTER
&& global_regs
[regno
])
2178 /* Make sure insns to set the stack pointer aren't deleted. */
2179 if (regno
== STACK_POINTER_REGNUM
)
2182 /* ??? These bits might be redundant with the force live bits
2183 in calculate_global_regs_live. We would delete from
2184 sequential sets; whether this actually affects real code
2185 for anything but the stack pointer I don't know. */
2186 /* Make sure insns to set the frame pointer aren't deleted. */
2187 if (regno
== FRAME_POINTER_REGNUM
2188 && (! reload_completed
|| frame_pointer_needed
))
2190 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
2191 if (regno
== HARD_FRAME_POINTER_REGNUM
2192 && (! reload_completed
|| frame_pointer_needed
))
2196 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
2197 /* Make sure insns to set arg pointer are never deleted
2198 (if the arg pointer isn't fixed, there will be a USE
2199 for it, so we can treat it normally). */
2200 if (regno
== ARG_POINTER_REGNUM
&& fixed_regs
[regno
])
2204 /* Otherwise, the set is dead. */
2210 /* If performing several activities, insn is dead if each activity
2211 is individually dead. Also, CLOBBERs and USEs can be ignored; a
2212 CLOBBER or USE that's inside a PARALLEL doesn't make the insn
2214 else if (code
== PARALLEL
)
2216 int i
= XVECLEN (x
, 0);
2218 for (i
--; i
>= 0; i
--)
2219 if (GET_CODE (XVECEXP (x
, 0, i
)) != CLOBBER
2220 && GET_CODE (XVECEXP (x
, 0, i
)) != USE
2221 && ! insn_dead_p (pbi
, XVECEXP (x
, 0, i
), call_ok
, NULL_RTX
))
2227 /* A CLOBBER of a pseudo-register that is dead serves no purpose. That
2228 is not necessarily true for hard registers until after reload. */
2229 else if (code
== CLOBBER
)
2231 if (REG_P (XEXP (x
, 0))
2232 && (REGNO (XEXP (x
, 0)) >= FIRST_PSEUDO_REGISTER
2233 || reload_completed
)
2234 && ! REGNO_REG_SET_P (pbi
->reg_live
, REGNO (XEXP (x
, 0))))
2238 /* ??? A base USE is a historical relic. It ought not be needed anymore.
2239 Instances where it is still used are either (1) temporary and the USE
2240 escaped the pass, (2) cruft and the USE need not be emitted anymore,
2241 or (3) hiding bugs elsewhere that are not properly representing data
2247 /* If INSN is the last insn in a libcall, and assuming INSN is dead,
2248 return 1 if the entire library call is dead.
2249 This is true if INSN copies a register (hard or pseudo)
2250 and if the hard return reg of the call insn is dead.
2251 (The caller should have tested the destination of the SET inside
2252 INSN already for death.)
2254 If this insn doesn't just copy a register, then we don't
2255 have an ordinary libcall. In that case, cse could not have
2256 managed to substitute the source for the dest later on,
2257 so we can assume the libcall is dead.
2259 PBI is the block info giving pseudoregs live before this insn.
2260 NOTE is the REG_RETVAL note of the insn. */
2263 libcall_dead_p (struct propagate_block_info
*pbi
, rtx note
, rtx insn
)
2265 rtx x
= single_set (insn
);
2269 rtx r
= SET_SRC (x
);
2273 rtx call
= XEXP (note
, 0);
2277 /* Find the call insn. */
2278 while (call
!= insn
&& !CALL_P (call
))
2279 call
= NEXT_INSN (call
);
2281 /* If there is none, do nothing special,
2282 since ordinary death handling can understand these insns. */
2286 /* See if the hard reg holding the value is dead.
2287 If this is a PARALLEL, find the call within it. */
2288 call_pat
= PATTERN (call
);
2289 if (GET_CODE (call_pat
) == PARALLEL
)
2291 for (i
= XVECLEN (call_pat
, 0) - 1; i
>= 0; i
--)
2292 if (GET_CODE (XVECEXP (call_pat
, 0, i
)) == SET
2293 && GET_CODE (SET_SRC (XVECEXP (call_pat
, 0, i
))) == CALL
)
2296 /* This may be a library call that is returning a value
2297 via invisible pointer. Do nothing special, since
2298 ordinary death handling can understand these insns. */
2302 call_pat
= XVECEXP (call_pat
, 0, i
);
2305 return insn_dead_p (pbi
, call_pat
, 1, REG_NOTES (call
));
2311 /* 1 if register REGNO was alive at a place where `setjmp' was called
2312 and was set more than once or is an argument.
2313 Such regs may be clobbered by `longjmp'. */
2316 regno_clobbered_at_setjmp (int regno
)
2318 if (n_basic_blocks
== 0)
2321 return ((REG_N_SETS (regno
) > 1
2322 || REGNO_REG_SET_P (ENTRY_BLOCK_PTR
->global_live_at_end
, regno
))
2323 && REGNO_REG_SET_P (regs_live_at_setjmp
, regno
));
2326 /* Add MEM to PBI->MEM_SET_LIST. MEM should be canonical. Respect the
2327 maximal list size; look for overlaps in mode and select the largest. */
2329 add_to_mem_set_list (struct propagate_block_info
*pbi
, rtx mem
)
2333 /* We don't know how large a BLKmode store is, so we must not
2334 take them into consideration. */
2335 if (GET_MODE (mem
) == BLKmode
)
2338 for (i
= pbi
->mem_set_list
; i
; i
= XEXP (i
, 1))
2340 rtx e
= XEXP (i
, 0);
2341 if (rtx_equal_p (XEXP (mem
, 0), XEXP (e
, 0)))
2343 if (GET_MODE_SIZE (GET_MODE (mem
)) > GET_MODE_SIZE (GET_MODE (e
)))
2346 /* If we must store a copy of the mem, we can just modify
2347 the mode of the stored copy. */
2348 if (pbi
->flags
& PROP_AUTOINC
)
2349 PUT_MODE (e
, GET_MODE (mem
));
2358 if (pbi
->mem_set_list_len
< MAX_MEM_SET_LIST_LEN
)
2361 /* Store a copy of mem, otherwise the address may be
2362 scrogged by find_auto_inc. */
2363 if (pbi
->flags
& PROP_AUTOINC
)
2364 mem
= shallow_copy_rtx (mem
);
2366 pbi
->mem_set_list
= alloc_EXPR_LIST (0, mem
, pbi
->mem_set_list
);
2367 pbi
->mem_set_list_len
++;
2371 /* INSN references memory, possibly using autoincrement addressing modes.
2372 Find any entries on the mem_set_list that need to be invalidated due
2373 to an address change. */
2376 invalidate_mems_from_autoinc (rtx
*px
, void *data
)
2379 struct propagate_block_info
*pbi
= data
;
2381 if (GET_RTX_CLASS (GET_CODE (x
)) == RTX_AUTOINC
)
2383 invalidate_mems_from_set (pbi
, XEXP (x
, 0));
2390 /* EXP is a REG. Remove any dependent entries from pbi->mem_set_list. */
2393 invalidate_mems_from_set (struct propagate_block_info
*pbi
, rtx exp
)
2395 rtx temp
= pbi
->mem_set_list
;
2396 rtx prev
= NULL_RTX
;
2401 next
= XEXP (temp
, 1);
2402 if (reg_overlap_mentioned_p (exp
, XEXP (temp
, 0)))
2404 /* Splice this entry out of the list. */
2406 XEXP (prev
, 1) = next
;
2408 pbi
->mem_set_list
= next
;
2409 free_EXPR_LIST_node (temp
);
2410 pbi
->mem_set_list_len
--;
2418 /* Process the registers that are set within X. Their bits are set to
2419 1 in the regset DEAD, because they are dead prior to this insn.
2421 If INSN is nonzero, it is the insn being processed.
2423 FLAGS is the set of operations to perform. */
2426 mark_set_regs (struct propagate_block_info
*pbi
, rtx x
, rtx insn
)
2428 rtx cond
= NULL_RTX
;
2431 int flags
= pbi
->flags
;
2434 for (link
= REG_NOTES (insn
); link
; link
= XEXP (link
, 1))
2436 if (REG_NOTE_KIND (link
) == REG_INC
)
2437 mark_set_1 (pbi
, SET
, XEXP (link
, 0),
2438 (GET_CODE (x
) == COND_EXEC
2439 ? COND_EXEC_TEST (x
) : NULL_RTX
),
2443 switch (code
= GET_CODE (x
))
2446 if (GET_CODE (XEXP (x
, 1)) == ASM_OPERANDS
)
2447 flags
|= PROP_ASM_SCAN
;
2450 mark_set_1 (pbi
, code
, SET_DEST (x
), cond
, insn
, flags
);
2454 cond
= COND_EXEC_TEST (x
);
2455 x
= COND_EXEC_CODE (x
);
2462 /* We must scan forwards. If we have an asm, we need to set
2463 the PROP_ASM_SCAN flag before scanning the clobbers. */
2464 for (i
= 0; i
< XVECLEN (x
, 0); i
++)
2466 rtx sub
= XVECEXP (x
, 0, i
);
2467 switch (code
= GET_CODE (sub
))
2470 if (cond
!= NULL_RTX
)
2473 cond
= COND_EXEC_TEST (sub
);
2474 sub
= COND_EXEC_CODE (sub
);
2475 if (GET_CODE (sub
) == SET
)
2477 if (GET_CODE (sub
) == CLOBBER
)
2483 if (GET_CODE (XEXP (sub
, 1)) == ASM_OPERANDS
)
2484 flags
|= PROP_ASM_SCAN
;
2488 mark_set_1 (pbi
, code
, SET_DEST (sub
), cond
, insn
, flags
);
2492 flags
|= PROP_ASM_SCAN
;
2507 /* Process a single set, which appears in INSN. REG (which may not
2508 actually be a REG, it may also be a SUBREG, PARALLEL, etc.) is
2509 being set using the CODE (which may be SET, CLOBBER, or COND_EXEC).
2510 If the set is conditional (because it appear in a COND_EXEC), COND
2511 will be the condition. */
2514 mark_set_1 (struct propagate_block_info
*pbi
, enum rtx_code code
, rtx reg
, rtx cond
, rtx insn
, int flags
)
2516 int regno_first
= -1, regno_last
= -1;
2517 unsigned long not_dead
= 0;
2520 /* Modifying just one hardware register of a multi-reg value or just a
2521 byte field of a register does not mean the value from before this insn
2522 is now dead. Of course, if it was dead after it's unused now. */
2524 switch (GET_CODE (reg
))
2527 /* Some targets place small structures in registers for return values of
2528 functions. We have to detect this case specially here to get correct
2529 flow information. */
2530 for (i
= XVECLEN (reg
, 0) - 1; i
>= 0; i
--)
2531 if (XEXP (XVECEXP (reg
, 0, i
), 0) != 0)
2532 mark_set_1 (pbi
, code
, XEXP (XVECEXP (reg
, 0, i
), 0), cond
, insn
,
2538 case STRICT_LOW_PART
:
2539 /* ??? Assumes STRICT_LOW_PART not used on multi-word registers. */
2541 reg
= XEXP (reg
, 0);
2542 while (GET_CODE (reg
) == SUBREG
2543 || GET_CODE (reg
) == ZERO_EXTRACT
2544 || GET_CODE (reg
) == SIGN_EXTRACT
2545 || GET_CODE (reg
) == STRICT_LOW_PART
);
2548 not_dead
= (unsigned long) REGNO_REG_SET_P (pbi
->reg_live
, REGNO (reg
));
2552 regno_last
= regno_first
= REGNO (reg
);
2553 if (regno_first
< FIRST_PSEUDO_REGISTER
)
2554 regno_last
+= hard_regno_nregs
[regno_first
][GET_MODE (reg
)] - 1;
2558 if (REG_P (SUBREG_REG (reg
)))
2560 enum machine_mode outer_mode
= GET_MODE (reg
);
2561 enum machine_mode inner_mode
= GET_MODE (SUBREG_REG (reg
));
2563 /* Identify the range of registers affected. This is moderately
2564 tricky for hard registers. See alter_subreg. */
2566 regno_last
= regno_first
= REGNO (SUBREG_REG (reg
));
2567 if (regno_first
< FIRST_PSEUDO_REGISTER
)
2569 regno_first
+= subreg_regno_offset (regno_first
, inner_mode
,
2572 regno_last
= (regno_first
2573 + hard_regno_nregs
[regno_first
][outer_mode
] - 1);
2575 /* Since we've just adjusted the register number ranges, make
2576 sure REG matches. Otherwise some_was_live will be clear
2577 when it shouldn't have been, and we'll create incorrect
2578 REG_UNUSED notes. */
2579 reg
= gen_rtx_REG (outer_mode
, regno_first
);
2583 /* If the number of words in the subreg is less than the number
2584 of words in the full register, we have a well-defined partial
2585 set. Otherwise the high bits are undefined.
2587 This is only really applicable to pseudos, since we just took
2588 care of multi-word hard registers. */
2589 if (((GET_MODE_SIZE (outer_mode
)
2590 + UNITS_PER_WORD
- 1) / UNITS_PER_WORD
)
2591 < ((GET_MODE_SIZE (inner_mode
)
2592 + UNITS_PER_WORD
- 1) / UNITS_PER_WORD
))
2593 not_dead
= (unsigned long) REGNO_REG_SET_P (pbi
->reg_live
,
2596 reg
= SUBREG_REG (reg
);
2600 reg
= SUBREG_REG (reg
);
2607 /* If this set is a MEM, then it kills any aliased writes.
2608 If this set is a REG, then it kills any MEMs which use the reg. */
2609 if (optimize
&& (flags
& PROP_SCAN_DEAD_STORES
))
2612 invalidate_mems_from_set (pbi
, reg
);
2614 /* If the memory reference had embedded side effects (autoincrement
2615 address modes. Then we may need to kill some entries on the
2617 if (insn
&& MEM_P (reg
))
2618 for_each_rtx (&PATTERN (insn
), invalidate_mems_from_autoinc
, pbi
);
2620 if (MEM_P (reg
) && ! side_effects_p (reg
)
2621 /* ??? With more effort we could track conditional memory life. */
2623 add_to_mem_set_list (pbi
, canon_rtx (reg
));
2627 && ! (regno_first
== FRAME_POINTER_REGNUM
2628 && (! reload_completed
|| frame_pointer_needed
))
2629 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
2630 && ! (regno_first
== HARD_FRAME_POINTER_REGNUM
2631 && (! reload_completed
|| frame_pointer_needed
))
2633 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
2634 && ! (regno_first
== ARG_POINTER_REGNUM
&& fixed_regs
[regno_first
])
2638 int some_was_live
= 0, some_was_dead
= 0;
2640 for (i
= regno_first
; i
<= regno_last
; ++i
)
2642 int needed_regno
= REGNO_REG_SET_P (pbi
->reg_live
, i
);
2645 /* Order of the set operation matters here since both
2646 sets may be the same. */
2647 CLEAR_REGNO_REG_SET (pbi
->cond_local_set
, i
);
2648 if (cond
!= NULL_RTX
2649 && ! REGNO_REG_SET_P (pbi
->local_set
, i
))
2650 SET_REGNO_REG_SET (pbi
->cond_local_set
, i
);
2652 SET_REGNO_REG_SET (pbi
->local_set
, i
);
2654 if (code
!= CLOBBER
)
2655 SET_REGNO_REG_SET (pbi
->new_set
, i
);
2657 some_was_live
|= needed_regno
;
2658 some_was_dead
|= ! needed_regno
;
2661 #ifdef HAVE_conditional_execution
2662 /* Consider conditional death in deciding that the register needs
2664 if (some_was_live
&& ! not_dead
2665 /* The stack pointer is never dead. Well, not strictly true,
2666 but it's very difficult to tell from here. Hopefully
2667 combine_stack_adjustments will fix up the most egregious
2669 && regno_first
!= STACK_POINTER_REGNUM
)
2671 for (i
= regno_first
; i
<= regno_last
; ++i
)
2672 if (! mark_regno_cond_dead (pbi
, i
, cond
))
2673 not_dead
|= ((unsigned long) 1) << (i
- regno_first
);
2677 /* Additional data to record if this is the final pass. */
2678 if (flags
& (PROP_LOG_LINKS
| PROP_REG_INFO
2679 | PROP_DEATH_NOTES
| PROP_AUTOINC
))
2682 int blocknum
= pbi
->bb
->index
;
2685 if (flags
& (PROP_LOG_LINKS
| PROP_AUTOINC
))
2687 y
= pbi
->reg_next_use
[regno_first
];
2689 /* The next use is no longer next, since a store intervenes. */
2690 for (i
= regno_first
; i
<= regno_last
; ++i
)
2691 pbi
->reg_next_use
[i
] = 0;
2694 if (flags
& PROP_REG_INFO
)
2696 for (i
= regno_first
; i
<= regno_last
; ++i
)
2698 /* Count (weighted) references, stores, etc. This counts a
2699 register twice if it is modified, but that is correct. */
2700 REG_N_SETS (i
) += 1;
2701 REG_N_REFS (i
) += 1;
2702 REG_FREQ (i
) += REG_FREQ_FROM_BB (pbi
->bb
);
2704 /* The insns where a reg is live are normally counted
2705 elsewhere, but we want the count to include the insn
2706 where the reg is set, and the normal counting mechanism
2707 would not count it. */
2708 REG_LIVE_LENGTH (i
) += 1;
2711 /* If this is a hard reg, record this function uses the reg. */
2712 if (regno_first
< FIRST_PSEUDO_REGISTER
)
2714 for (i
= regno_first
; i
<= regno_last
; i
++)
2715 regs_ever_live
[i
] = 1;
2716 if (flags
& PROP_ASM_SCAN
)
2717 for (i
= regno_first
; i
<= regno_last
; i
++)
2718 regs_asm_clobbered
[i
] = 1;
2722 /* Keep track of which basic blocks each reg appears in. */
2723 if (REG_BASIC_BLOCK (regno_first
) == REG_BLOCK_UNKNOWN
)
2724 REG_BASIC_BLOCK (regno_first
) = blocknum
;
2725 else if (REG_BASIC_BLOCK (regno_first
) != blocknum
)
2726 REG_BASIC_BLOCK (regno_first
) = REG_BLOCK_GLOBAL
;
2730 if (! some_was_dead
)
2732 if (flags
& PROP_LOG_LINKS
)
2734 /* Make a logical link from the next following insn
2735 that uses this register, back to this insn.
2736 The following insns have already been processed.
2738 We don't build a LOG_LINK for hard registers containing
2739 in ASM_OPERANDs. If these registers get replaced,
2740 we might wind up changing the semantics of the insn,
2741 even if reload can make what appear to be valid
2744 We don't build a LOG_LINK for global registers to
2745 or from a function call. We don't want to let
2746 combine think that it knows what is going on with
2747 global registers. */
2748 if (y
&& (BLOCK_NUM (y
) == blocknum
)
2749 && (regno_first
>= FIRST_PSEUDO_REGISTER
2750 || (asm_noperands (PATTERN (y
)) < 0
2751 && ! ((CALL_P (insn
)
2753 && global_regs
[regno_first
]))))
2754 LOG_LINKS (y
) = alloc_INSN_LIST (insn
, LOG_LINKS (y
));
2759 else if (! some_was_live
)
2761 if (flags
& PROP_REG_INFO
)
2762 REG_N_DEATHS (regno_first
) += 1;
2764 if (flags
& PROP_DEATH_NOTES
)
2766 /* Note that dead stores have already been deleted
2767 when possible. If we get here, we have found a
2768 dead store that cannot be eliminated (because the
2769 same insn does something useful). Indicate this
2770 by marking the reg being set as dying here. */
2772 = alloc_EXPR_LIST (REG_UNUSED
, reg
, REG_NOTES (insn
));
2777 if (flags
& PROP_DEATH_NOTES
)
2779 /* This is a case where we have a multi-word hard register
2780 and some, but not all, of the words of the register are
2781 needed in subsequent insns. Write REG_UNUSED notes
2782 for those parts that were not needed. This case should
2785 for (i
= regno_first
; i
<= regno_last
; ++i
)
2786 if (! REGNO_REG_SET_P (pbi
->reg_live
, i
))
2788 = alloc_EXPR_LIST (REG_UNUSED
,
2795 /* Mark the register as being dead. */
2797 /* The stack pointer is never dead. Well, not strictly true,
2798 but it's very difficult to tell from here. Hopefully
2799 combine_stack_adjustments will fix up the most egregious
2801 && regno_first
!= STACK_POINTER_REGNUM
)
2803 for (i
= regno_first
; i
<= regno_last
; ++i
)
2804 if (!(not_dead
& (((unsigned long) 1) << (i
- regno_first
))))
2806 if ((pbi
->flags
& PROP_REG_INFO
)
2807 && REGNO_REG_SET_P (pbi
->reg_live
, i
))
2809 REG_LIVE_LENGTH (i
) += pbi
->insn_num
- reg_deaths
[i
];
2812 CLEAR_REGNO_REG_SET (pbi
->reg_live
, i
);
2816 else if (REG_P (reg
))
2818 if (flags
& (PROP_LOG_LINKS
| PROP_AUTOINC
))
2819 pbi
->reg_next_use
[regno_first
] = 0;
2821 if ((flags
& PROP_REG_INFO
) != 0
2822 && (flags
& PROP_ASM_SCAN
) != 0
2823 && regno_first
< FIRST_PSEUDO_REGISTER
)
2825 for (i
= regno_first
; i
<= regno_last
; i
++)
2826 regs_asm_clobbered
[i
] = 1;
2830 /* If this is the last pass and this is a SCRATCH, show it will be dying
2831 here and count it. */
2832 else if (GET_CODE (reg
) == SCRATCH
)
2834 if (flags
& PROP_DEATH_NOTES
)
2836 = alloc_EXPR_LIST (REG_UNUSED
, reg
, REG_NOTES (insn
));
2840 #ifdef HAVE_conditional_execution
2841 /* Mark REGNO conditionally dead.
2842 Return true if the register is now unconditionally dead. */
2845 mark_regno_cond_dead (struct propagate_block_info
*pbi
, int regno
, rtx cond
)
2847 /* If this is a store to a predicate register, the value of the
2848 predicate is changing, we don't know that the predicate as seen
2849 before is the same as that seen after. Flush all dependent
2850 conditions from reg_cond_dead. This will make all such
2851 conditionally live registers unconditionally live. */
2852 if (REGNO_REG_SET_P (pbi
->reg_cond_reg
, regno
))
2853 flush_reg_cond_reg (pbi
, regno
);
2855 /* If this is an unconditional store, remove any conditional
2856 life that may have existed. */
2857 if (cond
== NULL_RTX
)
2858 splay_tree_remove (pbi
->reg_cond_dead
, regno
);
2861 splay_tree_node node
;
2862 struct reg_cond_life_info
*rcli
;
2865 /* Otherwise this is a conditional set. Record that fact.
2866 It may have been conditionally used, or there may be a
2867 subsequent set with a complimentary condition. */
2869 node
= splay_tree_lookup (pbi
->reg_cond_dead
, regno
);
2872 /* The register was unconditionally live previously.
2873 Record the current condition as the condition under
2874 which it is dead. */
2875 rcli
= xmalloc (sizeof (*rcli
));
2876 rcli
->condition
= cond
;
2877 rcli
->stores
= cond
;
2878 rcli
->orig_condition
= const0_rtx
;
2879 splay_tree_insert (pbi
->reg_cond_dead
, regno
,
2880 (splay_tree_value
) rcli
);
2882 SET_REGNO_REG_SET (pbi
->reg_cond_reg
, REGNO (XEXP (cond
, 0)));
2884 /* Not unconditionally dead. */
2889 /* The register was conditionally live previously.
2890 Add the new condition to the old. */
2891 rcli
= (struct reg_cond_life_info
*) node
->value
;
2892 ncond
= rcli
->condition
;
2893 ncond
= ior_reg_cond (ncond
, cond
, 1);
2894 if (rcli
->stores
== const0_rtx
)
2895 rcli
->stores
= cond
;
2896 else if (rcli
->stores
!= const1_rtx
)
2897 rcli
->stores
= ior_reg_cond (rcli
->stores
, cond
, 1);
2899 /* If the register is now unconditionally dead, remove the entry
2900 in the splay_tree. A register is unconditionally dead if the
2901 dead condition ncond is true. A register is also unconditionally
2902 dead if the sum of all conditional stores is an unconditional
2903 store (stores is true), and the dead condition is identically the
2904 same as the original dead condition initialized at the end of
2905 the block. This is a pointer compare, not an rtx_equal_p
2907 if (ncond
== const1_rtx
2908 || (ncond
== rcli
->orig_condition
&& rcli
->stores
== const1_rtx
))
2909 splay_tree_remove (pbi
->reg_cond_dead
, regno
);
2912 rcli
->condition
= ncond
;
2914 SET_REGNO_REG_SET (pbi
->reg_cond_reg
, REGNO (XEXP (cond
, 0)));
2916 /* Not unconditionally dead. */
2925 /* Called from splay_tree_delete for pbi->reg_cond_life. */
2928 free_reg_cond_life_info (splay_tree_value value
)
2930 struct reg_cond_life_info
*rcli
= (struct reg_cond_life_info
*) value
;
2934 /* Helper function for flush_reg_cond_reg. */
2937 flush_reg_cond_reg_1 (splay_tree_node node
, void *data
)
2939 struct reg_cond_life_info
*rcli
;
2940 int *xdata
= (int *) data
;
2941 unsigned int regno
= xdata
[0];
2943 /* Don't need to search if last flushed value was farther on in
2944 the in-order traversal. */
2945 if (xdata
[1] >= (int) node
->key
)
2948 /* Splice out portions of the expression that refer to regno. */
2949 rcli
= (struct reg_cond_life_info
*) node
->value
;
2950 rcli
->condition
= elim_reg_cond (rcli
->condition
, regno
);
2951 if (rcli
->stores
!= const0_rtx
&& rcli
->stores
!= const1_rtx
)
2952 rcli
->stores
= elim_reg_cond (rcli
->stores
, regno
);
2954 /* If the entire condition is now false, signal the node to be removed. */
2955 if (rcli
->condition
== const0_rtx
)
2957 xdata
[1] = node
->key
;
2960 else if (rcli
->condition
== const1_rtx
)
2966 /* Flush all (sub) expressions referring to REGNO from REG_COND_LIVE. */
2969 flush_reg_cond_reg (struct propagate_block_info
*pbi
, int regno
)
2975 while (splay_tree_foreach (pbi
->reg_cond_dead
,
2976 flush_reg_cond_reg_1
, pair
) == -1)
2977 splay_tree_remove (pbi
->reg_cond_dead
, pair
[1]);
2979 CLEAR_REGNO_REG_SET (pbi
->reg_cond_reg
, regno
);
2982 /* Logical arithmetic on predicate conditions. IOR, NOT and AND.
2983 For ior/and, the ADD flag determines whether we want to add the new
2984 condition X to the old one unconditionally. If it is zero, we will
2985 only return a new expression if X allows us to simplify part of
2986 OLD, otherwise we return NULL to the caller.
2987 If ADD is nonzero, we will return a new condition in all cases. The
2988 toplevel caller of one of these functions should always pass 1 for
2992 ior_reg_cond (rtx old
, rtx x
, int add
)
2996 if (COMPARISON_P (old
))
2998 if (COMPARISON_P (x
)
2999 && REVERSE_CONDEXEC_PREDICATES_P (GET_CODE (x
), GET_CODE (old
))
3000 && REGNO (XEXP (x
, 0)) == REGNO (XEXP (old
, 0)))
3002 if (GET_CODE (x
) == GET_CODE (old
)
3003 && REGNO (XEXP (x
, 0)) == REGNO (XEXP (old
, 0)))
3007 return gen_rtx_IOR (0, old
, x
);
3010 switch (GET_CODE (old
))
3013 op0
= ior_reg_cond (XEXP (old
, 0), x
, 0);
3014 op1
= ior_reg_cond (XEXP (old
, 1), x
, 0);
3015 if (op0
!= NULL
|| op1
!= NULL
)
3017 if (op0
== const0_rtx
)
3018 return op1
? op1
: gen_rtx_IOR (0, XEXP (old
, 1), x
);
3019 if (op1
== const0_rtx
)
3020 return op0
? op0
: gen_rtx_IOR (0, XEXP (old
, 0), x
);
3021 if (op0
== const1_rtx
|| op1
== const1_rtx
)
3024 op0
= gen_rtx_IOR (0, XEXP (old
, 0), x
);
3025 else if (rtx_equal_p (x
, op0
))
3026 /* (x | A) | x ~ (x | A). */
3029 op1
= gen_rtx_IOR (0, XEXP (old
, 1), x
);
3030 else if (rtx_equal_p (x
, op1
))
3031 /* (A | x) | x ~ (A | x). */
3033 return gen_rtx_IOR (0, op0
, op1
);
3037 return gen_rtx_IOR (0, old
, x
);
3040 op0
= ior_reg_cond (XEXP (old
, 0), x
, 0);
3041 op1
= ior_reg_cond (XEXP (old
, 1), x
, 0);
3042 if (op0
!= NULL
|| op1
!= NULL
)
3044 if (op0
== const1_rtx
)
3045 return op1
? op1
: gen_rtx_IOR (0, XEXP (old
, 1), x
);
3046 if (op1
== const1_rtx
)
3047 return op0
? op0
: gen_rtx_IOR (0, XEXP (old
, 0), x
);
3048 if (op0
== const0_rtx
|| op1
== const0_rtx
)
3051 op0
= gen_rtx_IOR (0, XEXP (old
, 0), x
);
3052 else if (rtx_equal_p (x
, op0
))
3053 /* (x & A) | x ~ x. */
3056 op1
= gen_rtx_IOR (0, XEXP (old
, 1), x
);
3057 else if (rtx_equal_p (x
, op1
))
3058 /* (A & x) | x ~ x. */
3060 return gen_rtx_AND (0, op0
, op1
);
3064 return gen_rtx_IOR (0, old
, x
);
3067 op0
= and_reg_cond (XEXP (old
, 0), not_reg_cond (x
), 0);
3069 return not_reg_cond (op0
);
3072 return gen_rtx_IOR (0, old
, x
);
3080 not_reg_cond (rtx x
)
3082 enum rtx_code x_code
;
3084 if (x
== const0_rtx
)
3086 else if (x
== const1_rtx
)
3088 x_code
= GET_CODE (x
);
3091 if (COMPARISON_P (x
)
3092 && REG_P (XEXP (x
, 0)))
3094 if (XEXP (x
, 1) != const0_rtx
)
3097 return gen_rtx_fmt_ee (reverse_condition (x_code
),
3098 VOIDmode
, XEXP (x
, 0), const0_rtx
);
3100 return gen_rtx_NOT (0, x
);
3104 and_reg_cond (rtx old
, rtx x
, int add
)
3108 if (COMPARISON_P (old
))
3110 if (COMPARISON_P (x
)
3111 && GET_CODE (x
) == reverse_condition (GET_CODE (old
))
3112 && REGNO (XEXP (x
, 0)) == REGNO (XEXP (old
, 0)))
3114 if (GET_CODE (x
) == GET_CODE (old
)
3115 && REGNO (XEXP (x
, 0)) == REGNO (XEXP (old
, 0)))
3119 return gen_rtx_AND (0, old
, x
);
3122 switch (GET_CODE (old
))
3125 op0
= and_reg_cond (XEXP (old
, 0), x
, 0);
3126 op1
= and_reg_cond (XEXP (old
, 1), x
, 0);
3127 if (op0
!= NULL
|| op1
!= NULL
)
3129 if (op0
== const0_rtx
)
3130 return op1
? op1
: gen_rtx_AND (0, XEXP (old
, 1), x
);
3131 if (op1
== const0_rtx
)
3132 return op0
? op0
: gen_rtx_AND (0, XEXP (old
, 0), x
);
3133 if (op0
== const1_rtx
|| op1
== const1_rtx
)
3136 op0
= gen_rtx_AND (0, XEXP (old
, 0), x
);
3137 else if (rtx_equal_p (x
, op0
))
3138 /* (x | A) & x ~ x. */
3141 op1
= gen_rtx_AND (0, XEXP (old
, 1), x
);
3142 else if (rtx_equal_p (x
, op1
))
3143 /* (A | x) & x ~ x. */
3145 return gen_rtx_IOR (0, op0
, op1
);
3149 return gen_rtx_AND (0, old
, x
);
3152 op0
= and_reg_cond (XEXP (old
, 0), x
, 0);
3153 op1
= and_reg_cond (XEXP (old
, 1), x
, 0);
3154 if (op0
!= NULL
|| op1
!= NULL
)
3156 if (op0
== const1_rtx
)
3157 return op1
? op1
: gen_rtx_AND (0, XEXP (old
, 1), x
);
3158 if (op1
== const1_rtx
)
3159 return op0
? op0
: gen_rtx_AND (0, XEXP (old
, 0), x
);
3160 if (op0
== const0_rtx
|| op1
== const0_rtx
)
3163 op0
= gen_rtx_AND (0, XEXP (old
, 0), x
);
3164 else if (rtx_equal_p (x
, op0
))
3165 /* (x & A) & x ~ (x & A). */
3168 op1
= gen_rtx_AND (0, XEXP (old
, 1), x
);
3169 else if (rtx_equal_p (x
, op1
))
3170 /* (A & x) & x ~ (A & x). */
3172 return gen_rtx_AND (0, op0
, op1
);
3176 return gen_rtx_AND (0, old
, x
);
3179 op0
= ior_reg_cond (XEXP (old
, 0), not_reg_cond (x
), 0);
3181 return not_reg_cond (op0
);
3184 return gen_rtx_AND (0, old
, x
);
3191 /* Given a condition X, remove references to reg REGNO and return the
3192 new condition. The removal will be done so that all conditions
3193 involving REGNO are considered to evaluate to false. This function
3194 is used when the value of REGNO changes. */
3197 elim_reg_cond (rtx x
, unsigned int regno
)
3201 if (COMPARISON_P (x
))
3203 if (REGNO (XEXP (x
, 0)) == regno
)
3208 switch (GET_CODE (x
))
3211 op0
= elim_reg_cond (XEXP (x
, 0), regno
);
3212 op1
= elim_reg_cond (XEXP (x
, 1), regno
);
3213 if (op0
== const0_rtx
|| op1
== const0_rtx
)
3215 if (op0
== const1_rtx
)
3217 if (op1
== const1_rtx
)
3219 if (op0
== XEXP (x
, 0) && op1
== XEXP (x
, 1))
3221 return gen_rtx_AND (0, op0
, op1
);
3224 op0
= elim_reg_cond (XEXP (x
, 0), regno
);
3225 op1
= elim_reg_cond (XEXP (x
, 1), regno
);
3226 if (op0
== const1_rtx
|| op1
== const1_rtx
)
3228 if (op0
== const0_rtx
)
3230 if (op1
== const0_rtx
)
3232 if (op0
== XEXP (x
, 0) && op1
== XEXP (x
, 1))
3234 return gen_rtx_IOR (0, op0
, op1
);
3237 op0
= elim_reg_cond (XEXP (x
, 0), regno
);
3238 if (op0
== const0_rtx
)
3240 if (op0
== const1_rtx
)
3242 if (op0
!= XEXP (x
, 0))
3243 return not_reg_cond (op0
);
3250 #endif /* HAVE_conditional_execution */
3254 /* Try to substitute the auto-inc expression INC as the address inside
3255 MEM which occurs in INSN. Currently, the address of MEM is an expression
3256 involving INCR_REG, and INCR is the next use of INCR_REG; it is an insn
3257 that has a single set whose source is a PLUS of INCR_REG and something
3261 attempt_auto_inc (struct propagate_block_info
*pbi
, rtx inc
, rtx insn
,
3262 rtx mem
, rtx incr
, rtx incr_reg
)
3264 int regno
= REGNO (incr_reg
);
3265 rtx set
= single_set (incr
);
3266 rtx q
= SET_DEST (set
);
3267 rtx y
= SET_SRC (set
);
3268 int opnum
= XEXP (y
, 0) == incr_reg
? 0 : 1;
3270 /* Make sure this reg appears only once in this insn. */
3271 if (count_occurrences (PATTERN (insn
), incr_reg
, 1) != 1)
3274 if (dead_or_set_p (incr
, incr_reg
)
3275 /* Mustn't autoinc an eliminable register. */
3276 && (regno
>= FIRST_PSEUDO_REGISTER
3277 || ! TEST_HARD_REG_BIT (elim_reg_set
, regno
)))
3279 /* This is the simple case. Try to make the auto-inc. If
3280 we can't, we are done. Otherwise, we will do any
3281 needed updates below. */
3282 if (! validate_change (insn
, &XEXP (mem
, 0), inc
, 0))
3286 /* PREV_INSN used here to check the semi-open interval
3288 && ! reg_used_between_p (q
, PREV_INSN (insn
), incr
)
3289 /* We must also check for sets of q as q may be
3290 a call clobbered hard register and there may
3291 be a call between PREV_INSN (insn) and incr. */
3292 && ! reg_set_between_p (q
, PREV_INSN (insn
), incr
))
3294 /* We have *p followed sometime later by q = p+size.
3295 Both p and q must be live afterward,
3296 and q is not used between INSN and its assignment.
3297 Change it to q = p, ...*q..., q = q+size.
3298 Then fall into the usual case. */
3302 emit_move_insn (q
, incr_reg
);
3303 insns
= get_insns ();
3306 /* If we can't make the auto-inc, or can't make the
3307 replacement into Y, exit. There's no point in making
3308 the change below if we can't do the auto-inc and doing
3309 so is not correct in the pre-inc case. */
3312 validate_change (insn
, &XEXP (mem
, 0), inc
, 1);
3313 validate_change (incr
, &XEXP (y
, opnum
), q
, 1);
3314 if (! apply_change_group ())
3317 /* We now know we'll be doing this change, so emit the
3318 new insn(s) and do the updates. */
3319 emit_insn_before (insns
, insn
);
3321 if (BB_HEAD (pbi
->bb
) == insn
)
3322 BB_HEAD (pbi
->bb
) = insns
;
3324 /* INCR will become a NOTE and INSN won't contain a
3325 use of INCR_REG. If a use of INCR_REG was just placed in
3326 the insn before INSN, make that the next use.
3327 Otherwise, invalidate it. */
3328 if (NONJUMP_INSN_P (PREV_INSN (insn
))
3329 && GET_CODE (PATTERN (PREV_INSN (insn
))) == SET
3330 && SET_SRC (PATTERN (PREV_INSN (insn
))) == incr_reg
)
3331 pbi
->reg_next_use
[regno
] = PREV_INSN (insn
);
3333 pbi
->reg_next_use
[regno
] = 0;
3338 if ((pbi
->flags
& PROP_REG_INFO
)
3339 && !REGNO_REG_SET_P (pbi
->reg_live
, regno
))
3340 reg_deaths
[regno
] = pbi
->insn_num
;
3342 /* REGNO is now used in INCR which is below INSN, but
3343 it previously wasn't live here. If we don't mark
3344 it as live, we'll put a REG_DEAD note for it
3345 on this insn, which is incorrect. */
3346 SET_REGNO_REG_SET (pbi
->reg_live
, regno
);
3348 /* If there are any calls between INSN and INCR, show
3349 that REGNO now crosses them. */
3350 for (temp
= insn
; temp
!= incr
; temp
= NEXT_INSN (temp
))
3352 REG_N_CALLS_CROSSED (regno
)++;
3354 /* Invalidate alias info for Q since we just changed its value. */
3355 clear_reg_alias_info (q
);
3360 /* If we haven't returned, it means we were able to make the
3361 auto-inc, so update the status. First, record that this insn
3362 has an implicit side effect. */
3364 REG_NOTES (insn
) = alloc_EXPR_LIST (REG_INC
, incr_reg
, REG_NOTES (insn
));
3366 /* Modify the old increment-insn to simply copy
3367 the already-incremented value of our register. */
3368 if (! validate_change (incr
, &SET_SRC (set
), incr_reg
, 0))
3371 /* If that makes it a no-op (copying the register into itself) delete
3372 it so it won't appear to be a "use" and a "set" of this
3374 if (REGNO (SET_DEST (set
)) == REGNO (incr_reg
))
3376 /* If the original source was dead, it's dead now. */
3379 while ((note
= find_reg_note (incr
, REG_DEAD
, NULL_RTX
)) != NULL_RTX
)
3381 remove_note (incr
, note
);
3382 if (XEXP (note
, 0) != incr_reg
)
3384 unsigned int regno
= REGNO (XEXP (note
, 0));
3386 if ((pbi
->flags
& PROP_REG_INFO
)
3387 && REGNO_REG_SET_P (pbi
->reg_live
, regno
))
3389 REG_LIVE_LENGTH (regno
) += pbi
->insn_num
- reg_deaths
[regno
];
3390 reg_deaths
[regno
] = 0;
3392 CLEAR_REGNO_REG_SET (pbi
->reg_live
, REGNO (XEXP (note
, 0)));
3396 SET_INSN_DELETED (incr
);
3399 if (regno
>= FIRST_PSEUDO_REGISTER
)
3401 /* Count an extra reference to the reg. When a reg is
3402 incremented, spilling it is worse, so we want to make
3403 that less likely. */
3404 REG_FREQ (regno
) += REG_FREQ_FROM_BB (pbi
->bb
);
3406 /* Count the increment as a setting of the register,
3407 even though it isn't a SET in rtl. */
3408 REG_N_SETS (regno
)++;
3412 /* X is a MEM found in INSN. See if we can convert it into an auto-increment
3416 find_auto_inc (struct propagate_block_info
*pbi
, rtx x
, rtx insn
)
3418 rtx addr
= XEXP (x
, 0);
3419 HOST_WIDE_INT offset
= 0;
3420 rtx set
, y
, incr
, inc_val
;
3422 int size
= GET_MODE_SIZE (GET_MODE (x
));
3427 /* Here we detect use of an index register which might be good for
3428 postincrement, postdecrement, preincrement, or predecrement. */
3430 if (GET_CODE (addr
) == PLUS
&& GET_CODE (XEXP (addr
, 1)) == CONST_INT
)
3431 offset
= INTVAL (XEXP (addr
, 1)), addr
= XEXP (addr
, 0);
3436 regno
= REGNO (addr
);
3438 /* Is the next use an increment that might make auto-increment? */
3439 incr
= pbi
->reg_next_use
[regno
];
3440 if (incr
== 0 || BLOCK_NUM (incr
) != BLOCK_NUM (insn
))
3442 set
= single_set (incr
);
3443 if (set
== 0 || GET_CODE (set
) != SET
)
3447 if (GET_CODE (y
) != PLUS
)
3450 if (REG_P (XEXP (y
, 0)) && REGNO (XEXP (y
, 0)) == REGNO (addr
))
3451 inc_val
= XEXP (y
, 1);
3452 else if (REG_P (XEXP (y
, 1)) && REGNO (XEXP (y
, 1)) == REGNO (addr
))
3453 inc_val
= XEXP (y
, 0);
3457 if (GET_CODE (inc_val
) == CONST_INT
)
3459 if (HAVE_POST_INCREMENT
3460 && (INTVAL (inc_val
) == size
&& offset
== 0))
3461 attempt_auto_inc (pbi
, gen_rtx_POST_INC (Pmode
, addr
), insn
, x
,
3463 else if (HAVE_POST_DECREMENT
3464 && (INTVAL (inc_val
) == -size
&& offset
== 0))
3465 attempt_auto_inc (pbi
, gen_rtx_POST_DEC (Pmode
, addr
), insn
, x
,
3467 else if (HAVE_PRE_INCREMENT
3468 && (INTVAL (inc_val
) == size
&& offset
== size
))
3469 attempt_auto_inc (pbi
, gen_rtx_PRE_INC (Pmode
, addr
), insn
, x
,
3471 else if (HAVE_PRE_DECREMENT
3472 && (INTVAL (inc_val
) == -size
&& offset
== -size
))
3473 attempt_auto_inc (pbi
, gen_rtx_PRE_DEC (Pmode
, addr
), insn
, x
,
3475 else if (HAVE_POST_MODIFY_DISP
&& offset
== 0)
3476 attempt_auto_inc (pbi
, gen_rtx_POST_MODIFY (Pmode
, addr
,
3477 gen_rtx_PLUS (Pmode
,
3480 insn
, x
, incr
, addr
);
3481 else if (HAVE_PRE_MODIFY_DISP
&& offset
== INTVAL (inc_val
))
3482 attempt_auto_inc (pbi
, gen_rtx_PRE_MODIFY (Pmode
, addr
,
3483 gen_rtx_PLUS (Pmode
,
3486 insn
, x
, incr
, addr
);
3488 else if (REG_P (inc_val
)
3489 && ! reg_set_between_p (inc_val
, PREV_INSN (insn
),
3493 if (HAVE_POST_MODIFY_REG
&& offset
== 0)
3494 attempt_auto_inc (pbi
, gen_rtx_POST_MODIFY (Pmode
, addr
,
3495 gen_rtx_PLUS (Pmode
,
3498 insn
, x
, incr
, addr
);
3502 #endif /* AUTO_INC_DEC */
3505 mark_used_reg (struct propagate_block_info
*pbi
, rtx reg
,
3506 rtx cond ATTRIBUTE_UNUSED
, rtx insn
)
3508 unsigned int regno_first
, regno_last
, i
;
3509 int some_was_live
, some_was_dead
, some_not_set
;
3511 regno_last
= regno_first
= REGNO (reg
);
3512 if (regno_first
< FIRST_PSEUDO_REGISTER
)
3513 regno_last
+= hard_regno_nregs
[regno_first
][GET_MODE (reg
)] - 1;
3515 /* Find out if any of this register is live after this instruction. */
3516 some_was_live
= some_was_dead
= 0;
3517 for (i
= regno_first
; i
<= regno_last
; ++i
)
3519 int needed_regno
= REGNO_REG_SET_P (pbi
->reg_live
, i
);
3520 some_was_live
|= needed_regno
;
3521 some_was_dead
|= ! needed_regno
;
3524 /* Find out if any of the register was set this insn. */
3526 for (i
= regno_first
; i
<= regno_last
; ++i
)
3527 some_not_set
|= ! REGNO_REG_SET_P (pbi
->new_set
, i
);
3529 if (pbi
->flags
& (PROP_LOG_LINKS
| PROP_AUTOINC
))
3531 /* Record where each reg is used, so when the reg is set we know
3532 the next insn that uses it. */
3533 pbi
->reg_next_use
[regno_first
] = insn
;
3536 if (pbi
->flags
& PROP_REG_INFO
)
3538 if (regno_first
< FIRST_PSEUDO_REGISTER
)
3540 /* If this is a register we are going to try to eliminate,
3541 don't mark it live here. If we are successful in
3542 eliminating it, it need not be live unless it is used for
3543 pseudos, in which case it will have been set live when it
3544 was allocated to the pseudos. If the register will not
3545 be eliminated, reload will set it live at that point.
3547 Otherwise, record that this function uses this register. */
3548 /* ??? The PPC backend tries to "eliminate" on the pic
3549 register to itself. This should be fixed. In the mean
3550 time, hack around it. */
3552 if (! (TEST_HARD_REG_BIT (elim_reg_set
, regno_first
)
3553 && (regno_first
== FRAME_POINTER_REGNUM
3554 || regno_first
== ARG_POINTER_REGNUM
)))
3555 for (i
= regno_first
; i
<= regno_last
; ++i
)
3556 regs_ever_live
[i
] = 1;
3560 /* Keep track of which basic block each reg appears in. */
3562 int blocknum
= pbi
->bb
->index
;
3563 if (REG_BASIC_BLOCK (regno_first
) == REG_BLOCK_UNKNOWN
)
3564 REG_BASIC_BLOCK (regno_first
) = blocknum
;
3565 else if (REG_BASIC_BLOCK (regno_first
) != blocknum
)
3566 REG_BASIC_BLOCK (regno_first
) = REG_BLOCK_GLOBAL
;
3568 /* Count (weighted) number of uses of each reg. */
3569 REG_FREQ (regno_first
) += REG_FREQ_FROM_BB (pbi
->bb
);
3570 REG_N_REFS (regno_first
)++;
3572 for (i
= regno_first
; i
<= regno_last
; ++i
)
3573 if (! REGNO_REG_SET_P (pbi
->reg_live
, i
))
3575 #ifdef ENABLE_CHECKING
3579 reg_deaths
[i
] = pbi
->insn_num
;
3583 /* Record and count the insns in which a reg dies. If it is used in
3584 this insn and was dead below the insn then it dies in this insn.
3585 If it was set in this insn, we do not make a REG_DEAD note;
3586 likewise if we already made such a note. */
3587 if ((pbi
->flags
& (PROP_DEATH_NOTES
| PROP_REG_INFO
))
3591 /* Check for the case where the register dying partially
3592 overlaps the register set by this insn. */
3593 if (regno_first
!= regno_last
)
3594 for (i
= regno_first
; i
<= regno_last
; ++i
)
3595 some_was_live
|= REGNO_REG_SET_P (pbi
->new_set
, i
);
3597 /* If none of the words in X is needed, make a REG_DEAD note.
3598 Otherwise, we must make partial REG_DEAD notes. */
3599 if (! some_was_live
)
3601 if ((pbi
->flags
& PROP_DEATH_NOTES
)
3602 && ! find_regno_note (insn
, REG_DEAD
, regno_first
))
3604 = alloc_EXPR_LIST (REG_DEAD
, reg
, REG_NOTES (insn
));
3606 if (pbi
->flags
& PROP_REG_INFO
)
3607 REG_N_DEATHS (regno_first
)++;
3611 /* Don't make a REG_DEAD note for a part of a register
3612 that is set in the insn. */
3613 for (i
= regno_first
; i
<= regno_last
; ++i
)
3614 if (! REGNO_REG_SET_P (pbi
->reg_live
, i
)
3615 && ! dead_or_set_regno_p (insn
, i
))
3617 = alloc_EXPR_LIST (REG_DEAD
,
3623 /* Mark the register as being live. */
3624 for (i
= regno_first
; i
<= regno_last
; ++i
)
3626 #ifdef HAVE_conditional_execution
3627 int this_was_live
= REGNO_REG_SET_P (pbi
->reg_live
, i
);
3630 SET_REGNO_REG_SET (pbi
->reg_live
, i
);
3632 #ifdef HAVE_conditional_execution
3633 /* If this is a conditional use, record that fact. If it is later
3634 conditionally set, we'll know to kill the register. */
3635 if (cond
!= NULL_RTX
)
3637 splay_tree_node node
;
3638 struct reg_cond_life_info
*rcli
;
3643 node
= splay_tree_lookup (pbi
->reg_cond_dead
, i
);
3646 /* The register was unconditionally live previously.
3647 No need to do anything. */
3651 /* The register was conditionally live previously.
3652 Subtract the new life cond from the old death cond. */
3653 rcli
= (struct reg_cond_life_info
*) node
->value
;
3654 ncond
= rcli
->condition
;
3655 ncond
= and_reg_cond (ncond
, not_reg_cond (cond
), 1);
3657 /* If the register is now unconditionally live,
3658 remove the entry in the splay_tree. */
3659 if (ncond
== const0_rtx
)
3660 splay_tree_remove (pbi
->reg_cond_dead
, i
);
3663 rcli
->condition
= ncond
;
3664 SET_REGNO_REG_SET (pbi
->reg_cond_reg
,
3665 REGNO (XEXP (cond
, 0)));
3671 /* The register was not previously live at all. Record
3672 the condition under which it is still dead. */
3673 rcli
= xmalloc (sizeof (*rcli
));
3674 rcli
->condition
= not_reg_cond (cond
);
3675 rcli
->stores
= const0_rtx
;
3676 rcli
->orig_condition
= const0_rtx
;
3677 splay_tree_insert (pbi
->reg_cond_dead
, i
,
3678 (splay_tree_value
) rcli
);
3680 SET_REGNO_REG_SET (pbi
->reg_cond_reg
, REGNO (XEXP (cond
, 0)));
3683 else if (this_was_live
)
3685 /* The register may have been conditionally live previously, but
3686 is now unconditionally live. Remove it from the conditionally
3687 dead list, so that a conditional set won't cause us to think
3689 splay_tree_remove (pbi
->reg_cond_dead
, i
);
3695 /* Scan expression X and store a 1-bit in NEW_LIVE for each reg it uses.
3696 This is done assuming the registers needed from X are those that
3697 have 1-bits in PBI->REG_LIVE.
3699 INSN is the containing instruction. If INSN is dead, this function
3703 mark_used_regs (struct propagate_block_info
*pbi
, rtx x
, rtx cond
, rtx insn
)
3707 int flags
= pbi
->flags
;
3712 code
= GET_CODE (x
);
3733 /* If we are clobbering a MEM, mark any registers inside the address
3735 if (MEM_P (XEXP (x
, 0)))
3736 mark_used_regs (pbi
, XEXP (XEXP (x
, 0), 0), cond
, insn
);
3740 /* Don't bother watching stores to mems if this is not the
3741 final pass. We'll not be deleting dead stores this round. */
3742 if (optimize
&& (flags
& PROP_SCAN_DEAD_STORES
))
3744 /* Invalidate the data for the last MEM stored, but only if MEM is
3745 something that can be stored into. */
3746 if (GET_CODE (XEXP (x
, 0)) == SYMBOL_REF
3747 && CONSTANT_POOL_ADDRESS_P (XEXP (x
, 0)))
3748 /* Needn't clear the memory set list. */
3752 rtx temp
= pbi
->mem_set_list
;
3753 rtx prev
= NULL_RTX
;
3758 next
= XEXP (temp
, 1);
3759 if (unchanging_anti_dependence (XEXP (temp
, 0), x
))
3761 /* Splice temp out of the list. */
3763 XEXP (prev
, 1) = next
;
3765 pbi
->mem_set_list
= next
;
3766 free_EXPR_LIST_node (temp
);
3767 pbi
->mem_set_list_len
--;
3775 /* If the memory reference had embedded side effects (autoincrement
3776 address modes. Then we may need to kill some entries on the
3779 for_each_rtx (&PATTERN (insn
), invalidate_mems_from_autoinc
, pbi
);
3783 if (flags
& PROP_AUTOINC
)
3784 find_auto_inc (pbi
, x
, insn
);
3789 #ifdef CANNOT_CHANGE_MODE_CLASS
3790 if ((flags
& PROP_REG_INFO
)
3791 && REG_P (SUBREG_REG (x
))
3792 && REGNO (SUBREG_REG (x
)) >= FIRST_PSEUDO_REGISTER
)
3793 bitmap_set_bit (&subregs_of_mode
, REGNO (SUBREG_REG (x
))
3798 /* While we're here, optimize this case. */
3805 /* See a register other than being set => mark it as needed. */
3806 mark_used_reg (pbi
, x
, cond
, insn
);
3811 rtx testreg
= SET_DEST (x
);
3814 /* If storing into MEM, don't show it as being used. But do
3815 show the address as being used. */
3816 if (MEM_P (testreg
))
3819 if (flags
& PROP_AUTOINC
)
3820 find_auto_inc (pbi
, testreg
, insn
);
3822 mark_used_regs (pbi
, XEXP (testreg
, 0), cond
, insn
);
3823 mark_used_regs (pbi
, SET_SRC (x
), cond
, insn
);
3827 /* Storing in STRICT_LOW_PART is like storing in a reg
3828 in that this SET might be dead, so ignore it in TESTREG.
3829 but in some other ways it is like using the reg.
3831 Storing in a SUBREG or a bit field is like storing the entire
3832 register in that if the register's value is not used
3833 then this SET is not needed. */
3834 while (GET_CODE (testreg
) == STRICT_LOW_PART
3835 || GET_CODE (testreg
) == ZERO_EXTRACT
3836 || GET_CODE (testreg
) == SIGN_EXTRACT
3837 || GET_CODE (testreg
) == SUBREG
)
3839 #ifdef CANNOT_CHANGE_MODE_CLASS
3840 if ((flags
& PROP_REG_INFO
)
3841 && GET_CODE (testreg
) == SUBREG
3842 && REG_P (SUBREG_REG (testreg
))
3843 && REGNO (SUBREG_REG (testreg
)) >= FIRST_PSEUDO_REGISTER
)
3844 bitmap_set_bit (&subregs_of_mode
, REGNO (SUBREG_REG (testreg
))
3846 + GET_MODE (testreg
));
3849 /* Modifying a single register in an alternate mode
3850 does not use any of the old value. But these other
3851 ways of storing in a register do use the old value. */
3852 if (GET_CODE (testreg
) == SUBREG
3853 && !((REG_BYTES (SUBREG_REG (testreg
))
3854 + UNITS_PER_WORD
- 1) / UNITS_PER_WORD
3855 > (REG_BYTES (testreg
)
3856 + UNITS_PER_WORD
- 1) / UNITS_PER_WORD
))
3861 testreg
= XEXP (testreg
, 0);
3864 /* If this is a store into a register or group of registers,
3865 recursively scan the value being stored. */
3867 if ((GET_CODE (testreg
) == PARALLEL
3868 && GET_MODE (testreg
) == BLKmode
)
3870 && (regno
= REGNO (testreg
),
3871 ! (regno
== FRAME_POINTER_REGNUM
3872 && (! reload_completed
|| frame_pointer_needed
)))
3873 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
3874 && ! (regno
== HARD_FRAME_POINTER_REGNUM
3875 && (! reload_completed
|| frame_pointer_needed
))
3877 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
3878 && ! (regno
== ARG_POINTER_REGNUM
&& fixed_regs
[regno
])
3883 mark_used_regs (pbi
, SET_DEST (x
), cond
, insn
);
3884 mark_used_regs (pbi
, SET_SRC (x
), cond
, insn
);
3891 case UNSPEC_VOLATILE
:
3895 /* Traditional and volatile asm instructions must be considered to use
3896 and clobber all hard registers, all pseudo-registers and all of
3897 memory. So must TRAP_IF and UNSPEC_VOLATILE operations.
3899 Consider for instance a volatile asm that changes the fpu rounding
3900 mode. An insn should not be moved across this even if it only uses
3901 pseudo-regs because it might give an incorrectly rounded result.
3903 ?!? Unfortunately, marking all hard registers as live causes massive
3904 problems for the register allocator and marking all pseudos as live
3905 creates mountains of uninitialized variable warnings.
3907 So for now, just clear the memory set list and mark any regs
3908 we can find in ASM_OPERANDS as used. */
3909 if (code
!= ASM_OPERANDS
|| MEM_VOLATILE_P (x
))
3911 free_EXPR_LIST_list (&pbi
->mem_set_list
);
3912 pbi
->mem_set_list_len
= 0;
3915 /* For all ASM_OPERANDS, we must traverse the vector of input operands.
3916 We can not just fall through here since then we would be confused
3917 by the ASM_INPUT rtx inside ASM_OPERANDS, which do not indicate
3918 traditional asms unlike their normal usage. */
3919 if (code
== ASM_OPERANDS
)
3923 for (j
= 0; j
< ASM_OPERANDS_INPUT_LENGTH (x
); j
++)
3924 mark_used_regs (pbi
, ASM_OPERANDS_INPUT (x
, j
), cond
, insn
);
3930 if (cond
!= NULL_RTX
)
3933 mark_used_regs (pbi
, COND_EXEC_TEST (x
), NULL_RTX
, insn
);
3935 cond
= COND_EXEC_TEST (x
);
3936 x
= COND_EXEC_CODE (x
);
3943 /* Recursively scan the operands of this expression. */
3946 const char * const fmt
= GET_RTX_FORMAT (code
);
3949 for (i
= GET_RTX_LENGTH (code
) - 1; i
>= 0; i
--)
3953 /* Tail recursive case: save a function call level. */
3959 mark_used_regs (pbi
, XEXP (x
, i
), cond
, insn
);
3961 else if (fmt
[i
] == 'E')
3964 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
3965 mark_used_regs (pbi
, XVECEXP (x
, i
, j
), cond
, insn
);
3974 try_pre_increment_1 (struct propagate_block_info
*pbi
, rtx insn
)
3976 /* Find the next use of this reg. If in same basic block,
3977 make it do pre-increment or pre-decrement if appropriate. */
3978 rtx x
= single_set (insn
);
3979 HOST_WIDE_INT amount
= ((GET_CODE (SET_SRC (x
)) == PLUS
? 1 : -1)
3980 * INTVAL (XEXP (SET_SRC (x
), 1)));
3981 int regno
= REGNO (SET_DEST (x
));
3982 rtx y
= pbi
->reg_next_use
[regno
];
3984 && SET_DEST (x
) != stack_pointer_rtx
3985 && BLOCK_NUM (y
) == BLOCK_NUM (insn
)
3986 /* Don't do this if the reg dies, or gets set in y; a standard addressing
3987 mode would be better. */
3988 && ! dead_or_set_p (y
, SET_DEST (x
))
3989 && try_pre_increment (y
, SET_DEST (x
), amount
))
3991 /* We have found a suitable auto-increment and already changed
3992 insn Y to do it. So flush this increment instruction. */
3993 propagate_block_delete_insn (insn
);
3995 /* Count a reference to this reg for the increment insn we are
3996 deleting. When a reg is incremented, spilling it is worse,
3997 so we want to make that less likely. */
3998 if (regno
>= FIRST_PSEUDO_REGISTER
)
4000 REG_FREQ (regno
) += REG_FREQ_FROM_BB (pbi
->bb
);
4001 REG_N_SETS (regno
)++;
4004 /* Flush any remembered memories depending on the value of
4005 the incremented register. */
4006 invalidate_mems_from_set (pbi
, SET_DEST (x
));
4013 /* Try to change INSN so that it does pre-increment or pre-decrement
4014 addressing on register REG in order to add AMOUNT to REG.
4015 AMOUNT is negative for pre-decrement.
4016 Returns 1 if the change could be made.
4017 This checks all about the validity of the result of modifying INSN. */
4020 try_pre_increment (rtx insn
, rtx reg
, HOST_WIDE_INT amount
)
4024 /* Nonzero if we can try to make a pre-increment or pre-decrement.
4025 For example, addl $4,r1; movl (r1),... can become movl +(r1),... */
4027 /* Nonzero if we can try to make a post-increment or post-decrement.
4028 For example, addl $4,r1; movl -4(r1),... can become movl (r1)+,...
4029 It is possible for both PRE_OK and POST_OK to be nonzero if the machine
4030 supports both pre-inc and post-inc, or both pre-dec and post-dec. */
4033 /* Nonzero if the opportunity actually requires post-inc or post-dec. */
4036 /* From the sign of increment, see which possibilities are conceivable
4037 on this target machine. */
4038 if (HAVE_PRE_INCREMENT
&& amount
> 0)
4040 if (HAVE_POST_INCREMENT
&& amount
> 0)
4043 if (HAVE_PRE_DECREMENT
&& amount
< 0)
4045 if (HAVE_POST_DECREMENT
&& amount
< 0)
4048 if (! (pre_ok
|| post_ok
))
4051 /* It is not safe to add a side effect to a jump insn
4052 because if the incremented register is spilled and must be reloaded
4053 there would be no way to store the incremented value back in memory. */
4060 use
= find_use_as_address (PATTERN (insn
), reg
, 0);
4061 if (post_ok
&& (use
== 0 || use
== (rtx
) (size_t) 1))
4063 use
= find_use_as_address (PATTERN (insn
), reg
, -amount
);
4067 if (use
== 0 || use
== (rtx
) (size_t) 1)
4070 if (GET_MODE_SIZE (GET_MODE (use
)) != (amount
> 0 ? amount
: - amount
))
4073 /* See if this combination of instruction and addressing mode exists. */
4074 if (! validate_change (insn
, &XEXP (use
, 0),
4075 gen_rtx_fmt_e (amount
> 0
4076 ? (do_post
? POST_INC
: PRE_INC
)
4077 : (do_post
? POST_DEC
: PRE_DEC
),
4081 /* Record that this insn now has an implicit side effect on X. */
4082 REG_NOTES (insn
) = alloc_EXPR_LIST (REG_INC
, reg
, REG_NOTES (insn
));
4086 #endif /* AUTO_INC_DEC */
4088 /* Find the place in the rtx X where REG is used as a memory address.
4089 Return the MEM rtx that so uses it.
4090 If PLUSCONST is nonzero, search instead for a memory address equivalent to
4091 (plus REG (const_int PLUSCONST)).
4093 If such an address does not appear, return 0.
4094 If REG appears more than once, or is used other than in such an address,
4098 find_use_as_address (rtx x
, rtx reg
, HOST_WIDE_INT plusconst
)
4100 enum rtx_code code
= GET_CODE (x
);
4101 const char * const fmt
= GET_RTX_FORMAT (code
);
4106 if (code
== MEM
&& XEXP (x
, 0) == reg
&& plusconst
== 0)
4109 if (code
== MEM
&& GET_CODE (XEXP (x
, 0)) == PLUS
4110 && XEXP (XEXP (x
, 0), 0) == reg
4111 && GET_CODE (XEXP (XEXP (x
, 0), 1)) == CONST_INT
4112 && INTVAL (XEXP (XEXP (x
, 0), 1)) == plusconst
)
4115 if (code
== SIGN_EXTRACT
|| code
== ZERO_EXTRACT
)
4117 /* If REG occurs inside a MEM used in a bit-field reference,
4118 that is unacceptable. */
4119 if (find_use_as_address (XEXP (x
, 0), reg
, 0) != 0)
4120 return (rtx
) (size_t) 1;
4124 return (rtx
) (size_t) 1;
4126 for (i
= GET_RTX_LENGTH (code
) - 1; i
>= 0; i
--)
4130 tem
= find_use_as_address (XEXP (x
, i
), reg
, plusconst
);
4134 return (rtx
) (size_t) 1;
4136 else if (fmt
[i
] == 'E')
4139 for (j
= XVECLEN (x
, i
) - 1; j
>= 0; j
--)
4141 tem
= find_use_as_address (XVECEXP (x
, i
, j
), reg
, plusconst
);
4145 return (rtx
) (size_t) 1;
4153 /* Write information about registers and basic blocks into FILE.
4154 This is part of making a debugging dump. */
4157 dump_regset (regset r
, FILE *outf
)
4162 fputs (" (nil)", outf
);
4166 EXECUTE_IF_SET_IN_REG_SET (r
, 0, i
,
4168 fprintf (outf
, " %d", i
);
4169 if (i
< FIRST_PSEUDO_REGISTER
)
4170 fprintf (outf
, " [%s]",
4175 /* Print a human-readable representation of R on the standard error
4176 stream. This function is designed to be used from within the
4180 debug_regset (regset r
)
4182 dump_regset (r
, stderr
);
4183 putc ('\n', stderr
);
4186 /* Recompute register set/reference counts immediately prior to register
4189 This avoids problems with set/reference counts changing to/from values
4190 which have special meanings to the register allocators.
4192 Additionally, the reference counts are the primary component used by the
4193 register allocators to prioritize pseudos for allocation to hard regs.
4194 More accurate reference counts generally lead to better register allocation.
4196 F is the first insn to be scanned.
4198 LOOP_STEP denotes how much loop_depth should be incremented per
4199 loop nesting level in order to increase the ref count more for
4200 references in a loop.
4202 It might be worthwhile to update REG_LIVE_LENGTH, REG_BASIC_BLOCK and
4203 possibly other information which is used by the register allocators. */
4206 recompute_reg_usage (rtx f ATTRIBUTE_UNUSED
, int loop_step ATTRIBUTE_UNUSED
)
4208 allocate_reg_life_data ();
4209 /* distribute_notes in combiner fails to convert some of the REG_UNUSED notes
4210 to REG_DEAD notes. This causes CHECK_DEAD_NOTES in sched1 to abort. To
4211 solve this update the DEATH_NOTES here. */
4212 update_life_info (NULL
, UPDATE_LIFE_LOCAL
, PROP_REG_INFO
| PROP_DEATH_NOTES
);
4215 /* Optionally removes all the REG_DEAD and REG_UNUSED notes from a set of
4216 blocks. If BLOCKS is NULL, assume the universal set. Returns a count
4217 of the number of registers that died. */
4220 count_or_remove_death_notes (sbitmap blocks
, int kill
)
4226 /* This used to be a loop over all the blocks with a membership test
4227 inside the loop. That can be amazingly expensive on a large CFG
4228 when only a small number of bits are set in BLOCKs (for example,
4229 the calls from the scheduler typically have very few bits set).
4231 For extra credit, someone should convert BLOCKS to a bitmap rather
4235 EXECUTE_IF_SET_IN_SBITMAP (blocks
, 0, i
,
4237 count
+= count_or_remove_death_notes_bb (BASIC_BLOCK (i
), kill
);
4244 count
+= count_or_remove_death_notes_bb (bb
, kill
);
4251 /* Optionally removes all the REG_DEAD and REG_UNUSED notes from basic
4252 block BB. Returns a count of the number of registers that died. */
4255 count_or_remove_death_notes_bb (basic_block bb
, int kill
)
4260 for (insn
= BB_HEAD (bb
); ; insn
= NEXT_INSN (insn
))
4264 rtx
*pprev
= ®_NOTES (insn
);
4269 switch (REG_NOTE_KIND (link
))
4272 if (REG_P (XEXP (link
, 0)))
4274 rtx reg
= XEXP (link
, 0);
4277 if (REGNO (reg
) >= FIRST_PSEUDO_REGISTER
)
4280 n
= hard_regno_nregs
[REGNO (reg
)][GET_MODE (reg
)];
4289 rtx next
= XEXP (link
, 1);
4290 free_EXPR_LIST_node (link
);
4291 *pprev
= link
= next
;
4297 pprev
= &XEXP (link
, 1);
4304 if (insn
== BB_END (bb
))
4311 /* Clear LOG_LINKS fields of insns in a selected blocks or whole chain
4312 if blocks is NULL. */
4315 clear_log_links (sbitmap blocks
)
4322 for (insn
= get_insns (); insn
; insn
= NEXT_INSN (insn
))
4324 free_INSN_LIST_list (&LOG_LINKS (insn
));
4327 EXECUTE_IF_SET_IN_SBITMAP (blocks
, 0, i
,
4329 basic_block bb
= BASIC_BLOCK (i
);
4331 for (insn
= BB_HEAD (bb
); insn
!= NEXT_INSN (BB_END (bb
));
4332 insn
= NEXT_INSN (insn
))
4334 free_INSN_LIST_list (&LOG_LINKS (insn
));
4338 /* Given a register bitmap, turn on the bits in a HARD_REG_SET that
4339 correspond to the hard registers, if any, set in that map. This
4340 could be done far more efficiently by having all sorts of special-cases
4341 with moving single words, but probably isn't worth the trouble. */
4344 reg_set_to_hard_reg_set (HARD_REG_SET
*to
, bitmap from
)
4348 EXECUTE_IF_SET_IN_BITMAP
4351 if (i
>= FIRST_PSEUDO_REGISTER
)
4353 SET_HARD_REG_BIT (*to
, i
);