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) \
164 (GET_CODE ((x)) == reversed_comparison_code ((y), NULL))
168 /* Nonzero if the second flow pass has completed. */
171 /* Maximum register number used in this function, plus one. */
175 /* Indexed by n, giving various register information */
177 varray_type reg_n_info
;
179 /* Size of a regset for the current function,
180 in (1) bytes and (2) elements. */
185 /* Regset of regs live when calls to `setjmp'-like functions happen. */
186 /* ??? Does this exist only for the setjmp-clobbered warning message? */
188 regset regs_live_at_setjmp
;
190 /* List made of EXPR_LIST rtx's which gives pairs of pseudo registers
191 that have to go in the same hard reg.
192 The first two regs in the list are a pair, and the next two
193 are another pair, etc. */
196 /* Set of registers that may be eliminable. These are handled specially
197 in updating regs_ever_live. */
199 static HARD_REG_SET elim_reg_set
;
201 /* Holds information for tracking conditional register life information. */
202 struct reg_cond_life_info
204 /* A boolean expression of conditions under which a register is dead. */
206 /* Conditions under which a register is dead at the basic block end. */
209 /* A boolean expression of conditions under which a register has been
213 /* ??? Could store mask of bytes that are dead, so that we could finally
214 track lifetimes of multi-word registers accessed via subregs. */
217 /* For use in communicating between propagate_block and its subroutines.
218 Holds all information needed to compute life and def-use information. */
220 struct propagate_block_info
222 /* The basic block we're considering. */
225 /* Bit N is set if register N is conditionally or unconditionally live. */
228 /* Bit N is set if register N is set this insn. */
231 /* Element N is the next insn that uses (hard or pseudo) register N
232 within the current basic block; or zero, if there is no such insn. */
235 /* Contains a list of all the MEMs we are tracking for dead store
239 /* If non-null, record the set of registers set unconditionally in the
243 /* If non-null, record the set of registers set conditionally in the
245 regset cond_local_set
;
247 #ifdef HAVE_conditional_execution
248 /* Indexed by register number, holds a reg_cond_life_info for each
249 register that is not unconditionally live or dead. */
250 splay_tree reg_cond_dead
;
252 /* Bit N is set if register N is in an expression in reg_cond_dead. */
256 /* The length of mem_set_list. */
257 int mem_set_list_len
;
259 /* Nonzero if the value of CC0 is live. */
262 /* Flags controlling the set of information propagate_block collects. */
264 /* Index of instruction being processed. */
268 /* Number of dead insns removed. */
271 /* When PROP_REG_INFO set, array contains pbi->insn_num of instruction
272 where given register died. When the register is marked alive, we use the
273 information to compute amount of instructions life range cross.
274 (remember, we are walking backward). This can be computed as current
275 pbi->insn_num - reg_deaths[regno].
276 At the end of processing each basic block, the remaining live registers
277 are inspected and liferanges are increased same way so liverange of global
278 registers are computed correctly.
280 The array is maintained clear for dead registers, so it can be safely reused
281 for next basic block without expensive memset of the whole array after
282 reseting pbi->insn_num to 0. */
284 static int *reg_deaths
;
286 /* Maximum length of pbi->mem_set_list before we start dropping
287 new elements on the floor. */
288 #define MAX_MEM_SET_LIST_LEN 100
290 /* Forward declarations */
291 static int verify_wide_reg_1 (rtx
*, void *);
292 static void verify_wide_reg (int, basic_block
);
293 static void verify_local_live_at_start (regset
, basic_block
);
294 static void notice_stack_pointer_modification_1 (rtx
, rtx
, void *);
295 static void notice_stack_pointer_modification (void);
296 static void mark_reg (rtx
, void *);
297 static void mark_regs_live_at_end (regset
);
298 static void calculate_global_regs_live (sbitmap
, sbitmap
, int);
299 static void propagate_block_delete_insn (rtx
);
300 static rtx
propagate_block_delete_libcall (rtx
, rtx
);
301 static int insn_dead_p (struct propagate_block_info
*, rtx
, int, rtx
);
302 static int libcall_dead_p (struct propagate_block_info
*, rtx
, rtx
);
303 static void mark_set_regs (struct propagate_block_info
*, rtx
, rtx
);
304 static void mark_set_1 (struct propagate_block_info
*, enum rtx_code
, rtx
,
306 static int find_regno_partial (rtx
*, void *);
308 #ifdef HAVE_conditional_execution
309 static int mark_regno_cond_dead (struct propagate_block_info
*, int, rtx
);
310 static void free_reg_cond_life_info (splay_tree_value
);
311 static int flush_reg_cond_reg_1 (splay_tree_node
, void *);
312 static void flush_reg_cond_reg (struct propagate_block_info
*, int);
313 static rtx
elim_reg_cond (rtx
, unsigned int);
314 static rtx
ior_reg_cond (rtx
, rtx
, int);
315 static rtx
not_reg_cond (rtx
);
316 static rtx
and_reg_cond (rtx
, rtx
, int);
319 static void attempt_auto_inc (struct propagate_block_info
*, rtx
, rtx
, rtx
,
321 static void find_auto_inc (struct propagate_block_info
*, rtx
, rtx
);
322 static int try_pre_increment_1 (struct propagate_block_info
*, rtx
);
323 static int try_pre_increment (rtx
, rtx
, HOST_WIDE_INT
);
325 static void mark_used_reg (struct propagate_block_info
*, rtx
, rtx
, rtx
);
326 static void mark_used_regs (struct propagate_block_info
*, rtx
, rtx
, rtx
);
327 void debug_flow_info (void);
328 static void add_to_mem_set_list (struct propagate_block_info
*, rtx
);
329 static int invalidate_mems_from_autoinc (rtx
*, void *);
330 static void invalidate_mems_from_set (struct propagate_block_info
*, rtx
);
331 static void clear_log_links (sbitmap
);
332 static int count_or_remove_death_notes_bb (basic_block
, int);
333 static void allocate_bb_life_data (void);
335 /* Return the INSN immediately following the NOTE_INSN_BASIC_BLOCK
336 note associated with the BLOCK. */
339 first_insn_after_basic_block_note (basic_block block
)
343 /* Get the first instruction in the block. */
344 insn
= BB_HEAD (block
);
346 if (insn
== NULL_RTX
)
349 insn
= NEXT_INSN (insn
);
350 gcc_assert (NOTE_INSN_BASIC_BLOCK_P (insn
));
352 return NEXT_INSN (insn
);
355 /* Perform data flow analysis for the whole control flow graph.
356 FLAGS is a set of PROP_* flags to be used in accumulating flow info. */
359 life_analysis (FILE *file
, int flags
)
361 #ifdef ELIMINABLE_REGS
363 static const struct {const int from
, to
; } eliminables
[] = ELIMINABLE_REGS
;
366 /* Record which registers will be eliminated. We use this in
369 CLEAR_HARD_REG_SET (elim_reg_set
);
371 #ifdef ELIMINABLE_REGS
372 for (i
= 0; i
< (int) ARRAY_SIZE (eliminables
); i
++)
373 SET_HARD_REG_BIT (elim_reg_set
, eliminables
[i
].from
);
375 SET_HARD_REG_BIT (elim_reg_set
, FRAME_POINTER_REGNUM
);
379 #ifdef CANNOT_CHANGE_MODE_CLASS
380 if (flags
& PROP_REG_INFO
)
381 init_subregs_of_mode ();
385 flags
&= ~(PROP_LOG_LINKS
| PROP_AUTOINC
| PROP_ALLOW_CFG_CHANGES
);
387 /* The post-reload life analysis have (on a global basis) the same
388 registers live as was computed by reload itself. elimination
389 Otherwise offsets and such may be incorrect.
391 Reload will make some registers as live even though they do not
394 We don't want to create new auto-incs after reload, since they
395 are unlikely to be useful and can cause problems with shared
397 if (reload_completed
)
398 flags
&= ~(PROP_REG_INFO
| PROP_AUTOINC
);
400 /* We want alias analysis information for local dead store elimination. */
401 if (optimize
&& (flags
& PROP_SCAN_DEAD_STORES
))
402 init_alias_analysis ();
404 /* Always remove no-op moves. Do this before other processing so
405 that we don't have to keep re-scanning them. */
406 delete_noop_moves ();
408 /* Some targets can emit simpler epilogues if they know that sp was
409 not ever modified during the function. After reload, of course,
410 we've already emitted the epilogue so there's no sense searching. */
411 if (! reload_completed
)
412 notice_stack_pointer_modification ();
414 /* Allocate and zero out data structures that will record the
415 data from lifetime analysis. */
416 allocate_reg_life_data ();
417 allocate_bb_life_data ();
419 /* Find the set of registers live on function exit. */
420 mark_regs_live_at_end (EXIT_BLOCK_PTR
->global_live_at_start
);
422 /* "Update" life info from zero. It'd be nice to begin the
423 relaxation with just the exit and noreturn blocks, but that set
424 is not immediately handy. */
426 if (flags
& PROP_REG_INFO
)
428 memset (regs_ever_live
, 0, sizeof (regs_ever_live
));
429 memset (regs_asm_clobbered
, 0, sizeof (regs_asm_clobbered
));
431 update_life_info (NULL
, UPDATE_LIFE_GLOBAL
, flags
);
439 if (optimize
&& (flags
& PROP_SCAN_DEAD_STORES
))
440 end_alias_analysis ();
443 dump_flow_info (file
);
445 /* Removing dead insns should have made jumptables really dead. */
446 delete_dead_jumptables ();
449 /* A subroutine of verify_wide_reg, called through for_each_rtx.
450 Search for REGNO. If found, return 2 if it is not wider than
454 verify_wide_reg_1 (rtx
*px
, void *pregno
)
457 unsigned int regno
= *(int *) pregno
;
459 if (REG_P (x
) && REGNO (x
) == regno
)
461 if (GET_MODE_BITSIZE (GET_MODE (x
)) <= BITS_PER_WORD
)
468 /* A subroutine of verify_local_live_at_start. Search through insns
469 of BB looking for register REGNO. */
472 verify_wide_reg (int regno
, basic_block bb
)
474 rtx head
= BB_HEAD (bb
), end
= BB_END (bb
);
480 int r
= for_each_rtx (&PATTERN (head
), verify_wide_reg_1
, ®no
);
488 head
= NEXT_INSN (head
);
492 fprintf (dump_file
, "Register %d died unexpectedly.\n", regno
);
493 dump_bb (bb
, dump_file
, 0);
495 fatal_error ("internal consistency failure");
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);
519 fatal_error ("internal consistency failure");
525 reg_set_iterator rsi
;
527 /* Find the set of changed registers. */
528 XOR_REG_SET (new_live_at_start
, bb
->global_live_at_start
);
530 EXECUTE_IF_SET_IN_REG_SET (new_live_at_start
, 0, i
, rsi
)
532 /* No registers should die. */
533 if (REGNO_REG_SET_P (bb
->global_live_at_start
, i
))
538 "Register %d died unexpectedly.\n", i
);
539 dump_bb (bb
, dump_file
, 0);
541 fatal_error ("internal consistency failure");
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 gcc_assert (!(prop_flags
& PROP_ALLOW_CFG_CHANGES
)
590 || (extent
!= UPDATE_LIFE_LOCAL
&& !blocks
));
592 /* For a global update, we go through the relaxation process again. */
593 if (extent
!= UPDATE_LIFE_LOCAL
)
599 calculate_global_regs_live (blocks
, blocks
,
600 prop_flags
& (PROP_SCAN_DEAD_CODE
601 | PROP_SCAN_DEAD_STORES
602 | PROP_ALLOW_CFG_CHANGES
));
604 if ((prop_flags
& (PROP_KILL_DEAD_CODE
| PROP_ALLOW_CFG_CHANGES
))
605 != (PROP_KILL_DEAD_CODE
| PROP_ALLOW_CFG_CHANGES
))
608 /* Removing dead code may allow the CFG to be simplified which
609 in turn may allow for further dead code detection / removal. */
610 FOR_EACH_BB_REVERSE (bb
)
612 COPY_REG_SET (tmp
, bb
->global_live_at_end
);
613 changed
|= propagate_block (bb
, tmp
, NULL
, NULL
,
614 prop_flags
& (PROP_SCAN_DEAD_CODE
615 | PROP_SCAN_DEAD_STORES
616 | PROP_KILL_DEAD_CODE
));
619 /* Don't pass PROP_SCAN_DEAD_CODE or PROP_KILL_DEAD_CODE to
620 subsequent propagate_block calls, since removing or acting as
621 removing dead code can affect global register liveness, which
622 is supposed to be finalized for this call after this loop. */
623 stabilized_prop_flags
624 &= ~(PROP_SCAN_DEAD_CODE
| PROP_SCAN_DEAD_STORES
625 | PROP_KILL_DEAD_CODE
);
630 /* We repeat regardless of what cleanup_cfg says. If there were
631 instructions deleted above, that might have been only a
632 partial improvement (see MAX_MEM_SET_LIST_LEN usage).
633 Further improvement may be possible. */
634 cleanup_cfg (CLEANUP_EXPENSIVE
);
636 /* Zap the life information from the last round. If we don't
637 do this, we can wind up with registers that no longer appear
638 in the code being marked live at entry. */
641 CLEAR_REG_SET (bb
->global_live_at_start
);
642 CLEAR_REG_SET (bb
->global_live_at_end
);
646 /* If asked, remove notes from the blocks we'll update. */
647 if (extent
== UPDATE_LIFE_GLOBAL_RM_NOTES
)
648 count_or_remove_death_notes (blocks
, 1);
651 /* Clear log links in case we are asked to (re)compute them. */
652 if (prop_flags
& PROP_LOG_LINKS
)
653 clear_log_links (blocks
);
657 EXECUTE_IF_SET_IN_SBITMAP (blocks
, 0, i
,
659 bb
= BASIC_BLOCK (i
);
661 COPY_REG_SET (tmp
, bb
->global_live_at_end
);
662 propagate_block (bb
, tmp
, NULL
, NULL
, stabilized_prop_flags
);
664 if (extent
== UPDATE_LIFE_LOCAL
)
665 verify_local_live_at_start (tmp
, bb
);
670 FOR_EACH_BB_REVERSE (bb
)
672 COPY_REG_SET (tmp
, bb
->global_live_at_end
);
674 propagate_block (bb
, tmp
, NULL
, NULL
, stabilized_prop_flags
);
676 if (extent
== UPDATE_LIFE_LOCAL
)
677 verify_local_live_at_start (tmp
, bb
);
683 if (prop_flags
& PROP_REG_INFO
)
685 reg_set_iterator rsi
;
687 /* The only pseudos that are live at the beginning of the function
688 are those that were not set anywhere in the function. local-alloc
689 doesn't know how to handle these correctly, so mark them as not
690 local to any one basic block. */
691 EXECUTE_IF_SET_IN_REG_SET (ENTRY_BLOCK_PTR
->global_live_at_end
,
692 FIRST_PSEUDO_REGISTER
, i
, rsi
)
693 REG_BASIC_BLOCK (i
) = REG_BLOCK_GLOBAL
;
695 /* We have a problem with any pseudoreg that lives across the setjmp.
696 ANSI says that if a user variable does not change in value between
697 the setjmp and the longjmp, then the longjmp preserves it. This
698 includes longjmp from a place where the pseudo appears dead.
699 (In principle, the value still exists if it is in scope.)
700 If the pseudo goes in a hard reg, some other value may occupy
701 that hard reg where this pseudo is dead, thus clobbering the pseudo.
702 Conclusion: such a pseudo must not go in a hard reg. */
703 EXECUTE_IF_SET_IN_REG_SET (regs_live_at_setjmp
,
704 FIRST_PSEUDO_REGISTER
, i
, rsi
)
706 if (regno_reg_rtx
[i
] != 0)
708 REG_LIVE_LENGTH (i
) = -1;
709 REG_BASIC_BLOCK (i
) = REG_BLOCK_UNKNOWN
;
718 timevar_pop ((extent
== UPDATE_LIFE_LOCAL
|| blocks
)
719 ? TV_LIFE_UPDATE
: TV_LIFE
);
720 if (ndead
&& dump_file
)
721 fprintf (dump_file
, "deleted %i dead insns\n", ndead
);
725 /* Update life information in all blocks where BB_DIRTY is set. */
728 update_life_info_in_dirty_blocks (enum update_life_extent extent
, int prop_flags
)
730 sbitmap update_life_blocks
= sbitmap_alloc (last_basic_block
);
735 sbitmap_zero (update_life_blocks
);
738 if (extent
== UPDATE_LIFE_LOCAL
)
740 if (bb
->flags
& BB_DIRTY
)
742 SET_BIT (update_life_blocks
, bb
->index
);
748 /* ??? Bootstrap with -march=pentium4 fails to terminate
749 with only a partial life update. */
750 SET_BIT (update_life_blocks
, bb
->index
);
751 if (bb
->flags
& BB_DIRTY
)
757 retval
= update_life_info (update_life_blocks
, extent
, prop_flags
);
759 sbitmap_free (update_life_blocks
);
763 /* Free the variables allocated by find_basic_blocks. */
766 free_basic_block_vars (void)
768 if (basic_block_info
)
771 basic_block_info
= NULL
;
774 last_basic_block
= 0;
776 ENTRY_BLOCK_PTR
->aux
= NULL
;
777 ENTRY_BLOCK_PTR
->global_live_at_end
= NULL
;
778 EXIT_BLOCK_PTR
->aux
= NULL
;
779 EXIT_BLOCK_PTR
->global_live_at_start
= NULL
;
782 /* Delete any insns that copy a register to itself. */
785 delete_noop_moves (void)
793 for (insn
= BB_HEAD (bb
); insn
!= NEXT_INSN (BB_END (bb
)); insn
= next
)
795 next
= NEXT_INSN (insn
);
796 if (INSN_P (insn
) && noop_move_p (insn
))
800 /* If we're about to remove the first insn of a libcall
801 then move the libcall note to the next real insn and
802 update the retval note. */
803 if ((note
= find_reg_note (insn
, REG_LIBCALL
, NULL_RTX
))
804 && XEXP (note
, 0) != insn
)
806 rtx new_libcall_insn
= next_real_insn (insn
);
807 rtx retval_note
= find_reg_note (XEXP (note
, 0),
808 REG_RETVAL
, NULL_RTX
);
809 REG_NOTES (new_libcall_insn
)
810 = gen_rtx_INSN_LIST (REG_LIBCALL
, XEXP (note
, 0),
811 REG_NOTES (new_libcall_insn
));
812 XEXP (retval_note
, 0) = new_libcall_insn
;
815 delete_insn_and_edges (insn
);
820 if (nnoops
&& dump_file
)
821 fprintf (dump_file
, "deleted %i noop moves", nnoops
);
825 /* Delete any jump tables never referenced. We can't delete them at the
826 time of removing tablejump insn as they are referenced by the preceding
827 insns computing the destination, so we delay deleting and garbagecollect
828 them once life information is computed. */
830 delete_dead_jumptables (void)
833 for (insn
= get_insns (); insn
; insn
= next
)
835 next
= NEXT_INSN (insn
);
837 && LABEL_NUSES (insn
) == LABEL_PRESERVE_P (insn
)
839 && (GET_CODE (PATTERN (next
)) == ADDR_VEC
840 || GET_CODE (PATTERN (next
)) == ADDR_DIFF_VEC
))
843 fprintf (dump_file
, "Dead jumptable %i removed\n", INSN_UID (insn
));
844 delete_insn (NEXT_INSN (insn
));
846 next
= NEXT_INSN (next
);
851 /* Determine if the stack pointer is constant over the life of the function.
852 Only useful before prologues have been emitted. */
855 notice_stack_pointer_modification_1 (rtx x
, rtx pat ATTRIBUTE_UNUSED
,
856 void *data ATTRIBUTE_UNUSED
)
858 if (x
== stack_pointer_rtx
859 /* The stack pointer is only modified indirectly as the result
860 of a push until later in flow. See the comments in rtl.texi
861 regarding Embedded Side-Effects on Addresses. */
863 && GET_RTX_CLASS (GET_CODE (XEXP (x
, 0))) == RTX_AUTOINC
864 && XEXP (XEXP (x
, 0), 0) == stack_pointer_rtx
))
865 current_function_sp_is_unchanging
= 0;
869 notice_stack_pointer_modification (void)
874 /* Assume that the stack pointer is unchanging if alloca hasn't
876 current_function_sp_is_unchanging
= !current_function_calls_alloca
;
877 if (! current_function_sp_is_unchanging
)
881 FOR_BB_INSNS (bb
, insn
)
885 /* Check if insn modifies the stack pointer. */
886 note_stores (PATTERN (insn
),
887 notice_stack_pointer_modification_1
,
889 if (! current_function_sp_is_unchanging
)
895 /* Mark a register in SET. Hard registers in large modes get all
896 of their component registers set as well. */
899 mark_reg (rtx reg
, void *xset
)
901 regset set
= (regset
) xset
;
902 int regno
= REGNO (reg
);
904 gcc_assert (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
)
1027 gcc_assert (!bb
->aux
);
1030 tmp
= INITIALIZE_REG_SET (tmp_head
);
1031 new_live_at_end
= INITIALIZE_REG_SET (new_live_at_end_head
);
1032 invalidated_by_call
= INITIALIZE_REG_SET (invalidated_by_call_head
);
1034 /* Inconveniently, this is only readily available in hard reg set form. */
1035 for (i
= 0; i
< FIRST_PSEUDO_REGISTER
; ++i
)
1036 if (TEST_HARD_REG_BIT (regs_invalidated_by_call
, i
))
1037 SET_REGNO_REG_SET (invalidated_by_call
, i
);
1039 /* Create a worklist. Allocate an extra slot for ENTRY_BLOCK, and one
1040 because the `head == tail' style test for an empty queue doesn't
1041 work with a full queue. */
1042 queue
= xmalloc ((n_basic_blocks
+ 2) * sizeof (*queue
));
1044 qhead
= qend
= queue
+ n_basic_blocks
+ 2;
1046 /* Queue the blocks set in the initial mask. Do this in reverse block
1047 number order so that we are more likely for the first round to do
1048 useful work. We use AUX non-null to flag that the block is queued. */
1052 if (TEST_BIT (blocks_in
, bb
->index
))
1067 /* We clean aux when we remove the initially-enqueued bbs, but we
1068 don't enqueue ENTRY and EXIT initially, so clean them upfront and
1070 ENTRY_BLOCK_PTR
->aux
= EXIT_BLOCK_PTR
->aux
= NULL
;
1073 sbitmap_zero (blocks_out
);
1075 /* We work through the queue until there are no more blocks. What
1076 is live at the end of this block is precisely the union of what
1077 is live at the beginning of all its successors. So, we set its
1078 GLOBAL_LIVE_AT_END field based on the GLOBAL_LIVE_AT_START field
1079 for its successors. Then, we compute GLOBAL_LIVE_AT_START for
1080 this block by walking through the instructions in this block in
1081 reverse order and updating as we go. If that changed
1082 GLOBAL_LIVE_AT_START, we add the predecessors of the block to the
1083 queue; they will now need to recalculate GLOBAL_LIVE_AT_END.
1085 We are guaranteed to terminate, because GLOBAL_LIVE_AT_START
1086 never shrinks. If a register appears in GLOBAL_LIVE_AT_START, it
1087 must either be live at the end of the block, or used within the
1088 block. In the latter case, it will certainly never disappear
1089 from GLOBAL_LIVE_AT_START. In the former case, the register
1090 could go away only if it disappeared from GLOBAL_LIVE_AT_START
1091 for one of the successor blocks. By induction, that cannot
1093 while (qhead
!= qtail
)
1095 int rescan
, changed
;
1105 /* Begin by propagating live_at_start from the successor blocks. */
1106 CLEAR_REG_SET (new_live_at_end
);
1108 if (EDGE_COUNT (bb
->succs
) > 0)
1109 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
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
)
1118 bitmap_ior_and_compl_into (new_live_at_end
,
1119 sb
->global_live_at_start
,
1120 invalidated_by_call
);
1122 IOR_REG_SET (new_live_at_end
, sb
->global_live_at_start
);
1124 /* If a target saves one register in another (instead of on
1125 the stack) the save register will need to be live for EH. */
1126 if (e
->flags
& EDGE_EH
)
1127 for (i
= 0; i
< FIRST_PSEUDO_REGISTER
; i
++)
1129 SET_REGNO_REG_SET (new_live_at_end
, i
);
1133 /* This might be a noreturn function that throws. And
1134 even if it isn't, getting the unwind info right helps
1136 for (i
= 0; i
< FIRST_PSEUDO_REGISTER
; i
++)
1138 SET_REGNO_REG_SET (new_live_at_end
, i
);
1141 /* The all-important stack pointer must always be live. */
1142 SET_REGNO_REG_SET (new_live_at_end
, STACK_POINTER_REGNUM
);
1144 /* Before reload, there are a few registers that must be forced
1145 live everywhere -- which might not already be the case for
1146 blocks within infinite loops. */
1147 if (! reload_completed
)
1149 /* Any reference to any pseudo before reload is a potential
1150 reference of the frame pointer. */
1151 SET_REGNO_REG_SET (new_live_at_end
, FRAME_POINTER_REGNUM
);
1153 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
1154 /* Pseudos with argument area equivalences may require
1155 reloading via the argument pointer. */
1156 if (fixed_regs
[ARG_POINTER_REGNUM
])
1157 SET_REGNO_REG_SET (new_live_at_end
, ARG_POINTER_REGNUM
);
1160 /* Any constant, or pseudo with constant equivalences, may
1161 require reloading from memory using the pic register. */
1162 if ((unsigned) PIC_OFFSET_TABLE_REGNUM
!= INVALID_REGNUM
1163 && fixed_regs
[PIC_OFFSET_TABLE_REGNUM
])
1164 SET_REGNO_REG_SET (new_live_at_end
, PIC_OFFSET_TABLE_REGNUM
);
1167 if (bb
== ENTRY_BLOCK_PTR
)
1169 COPY_REG_SET (bb
->global_live_at_end
, new_live_at_end
);
1173 /* On our first pass through this block, we'll go ahead and continue.
1174 Recognize first pass by local_set NULL. On subsequent passes, we
1175 get to skip out early if live_at_end wouldn't have changed. */
1177 if (bb
->local_set
== NULL
)
1179 bb
->local_set
= OBSTACK_ALLOC_REG_SET (&flow_obstack
);
1180 bb
->cond_local_set
= OBSTACK_ALLOC_REG_SET (&flow_obstack
);
1185 /* If any bits were removed from live_at_end, we'll have to
1186 rescan the block. This wouldn't be necessary if we had
1187 precalculated local_live, however with PROP_SCAN_DEAD_CODE
1188 local_live is really dependent on live_at_end. */
1189 rescan
= bitmap_intersect_compl_p (bb
->global_live_at_end
,
1193 /* If any of the registers in the new live_at_end set are
1194 conditionally set in this basic block, we must rescan.
1195 This is because conditional lifetimes at the end of the
1196 block do not just take the live_at_end set into
1197 account, but also the liveness at the start of each
1198 successor block. We can miss changes in those sets if
1199 we only compare the new live_at_end against the
1201 rescan
= bitmap_intersect_p (new_live_at_end
,
1202 bb
->cond_local_set
);
1206 /* Find the set of changed bits. Take this opportunity
1207 to notice that this set is empty and early out. */
1208 bitmap_xor (tmp
, bb
->global_live_at_end
, new_live_at_end
);
1209 if (bitmap_empty_p (tmp
))
1212 /* If any of the changed bits overlap with local_set,
1213 we'll have to rescan the block. */
1214 rescan
= bitmap_intersect_p (tmp
, bb
->local_set
);
1218 /* Let our caller know that BB changed enough to require its
1219 death notes updated. */
1221 SET_BIT (blocks_out
, bb
->index
);
1225 /* Add to live_at_start the set of all registers in
1226 new_live_at_end that aren't in the old live_at_end. */
1228 changed
= bitmap_ior_and_compl_into (bb
->global_live_at_start
,
1230 bb
->global_live_at_end
);
1231 COPY_REG_SET (bb
->global_live_at_end
, new_live_at_end
);
1237 COPY_REG_SET (bb
->global_live_at_end
, new_live_at_end
);
1239 /* Rescan the block insn by insn to turn (a copy of) live_at_end
1240 into live_at_start. */
1241 propagate_block (bb
, new_live_at_end
, bb
->local_set
,
1242 bb
->cond_local_set
, flags
);
1244 /* If live_at start didn't change, no need to go farther. */
1245 if (REG_SET_EQUAL_P (bb
->global_live_at_start
, new_live_at_end
))
1248 COPY_REG_SET (bb
->global_live_at_start
, new_live_at_end
);
1251 /* Queue all predecessors of BB so that we may re-examine
1252 their live_at_end. */
1253 FOR_EACH_EDGE (e
, ei
, bb
->preds
)
1255 basic_block pb
= e
->src
;
1256 if (pb
->aux
== NULL
)
1267 FREE_REG_SET (new_live_at_end
);
1268 FREE_REG_SET (invalidated_by_call
);
1272 EXECUTE_IF_SET_IN_SBITMAP (blocks_out
, 0, i
,
1274 basic_block bb
= BASIC_BLOCK (i
);
1275 FREE_REG_SET (bb
->local_set
);
1276 FREE_REG_SET (bb
->cond_local_set
);
1283 FREE_REG_SET (bb
->local_set
);
1284 FREE_REG_SET (bb
->cond_local_set
);
1292 /* This structure is used to pass parameters to and from the
1293 the function find_regno_partial(). It is used to pass in the
1294 register number we are looking, as well as to return any rtx
1298 unsigned regno_to_find
;
1300 } find_regno_partial_param
;
1303 /* Find the rtx for the reg numbers specified in 'data' if it is
1304 part of an expression which only uses part of the register. Return
1305 it in the structure passed in. */
1307 find_regno_partial (rtx
*ptr
, void *data
)
1309 find_regno_partial_param
*param
= (find_regno_partial_param
*)data
;
1310 unsigned reg
= param
->regno_to_find
;
1311 param
->retval
= NULL_RTX
;
1313 if (*ptr
== NULL_RTX
)
1316 switch (GET_CODE (*ptr
))
1320 case STRICT_LOW_PART
:
1321 if (REG_P (XEXP (*ptr
, 0)) && REGNO (XEXP (*ptr
, 0)) == reg
)
1323 param
->retval
= XEXP (*ptr
, 0);
1329 if (REG_P (SUBREG_REG (*ptr
))
1330 && REGNO (SUBREG_REG (*ptr
)) == reg
)
1332 param
->retval
= SUBREG_REG (*ptr
);
1344 /* Process all immediate successors of the entry block looking for pseudo
1345 registers which are live on entry. Find all of those whose first
1346 instance is a partial register reference of some kind, and initialize
1347 them to 0 after the entry block. This will prevent bit sets within
1348 registers whose value is unknown, and may contain some kind of sticky
1349 bits we don't want. */
1352 initialize_uninitialized_subregs (void)
1356 unsigned reg
, did_something
= 0;
1357 find_regno_partial_param param
;
1360 FOR_EACH_EDGE (e
, ei
, ENTRY_BLOCK_PTR
->succs
)
1362 basic_block bb
= e
->dest
;
1363 regset map
= bb
->global_live_at_start
;
1364 reg_set_iterator rsi
;
1366 EXECUTE_IF_SET_IN_REG_SET (map
, FIRST_PSEUDO_REGISTER
, reg
, rsi
)
1368 int uid
= REGNO_FIRST_UID (reg
);
1371 /* Find an insn which mentions the register we are looking for.
1372 Its preferable to have an instance of the register's rtl since
1373 there may be various flags set which we need to duplicate.
1374 If we can't find it, its probably an automatic whose initial
1375 value doesn't matter, or hopefully something we don't care about. */
1376 for (i
= get_insns (); i
&& INSN_UID (i
) != uid
; i
= NEXT_INSN (i
))
1380 /* Found the insn, now get the REG rtx, if we can. */
1381 param
.regno_to_find
= reg
;
1382 for_each_rtx (&i
, find_regno_partial
, ¶m
);
1383 if (param
.retval
!= NULL_RTX
)
1386 emit_move_insn (param
.retval
,
1387 CONST0_RTX (GET_MODE (param
.retval
)));
1388 insn
= get_insns ();
1390 insert_insn_on_edge (insn
, e
);
1398 commit_edge_insertions ();
1399 return did_something
;
1403 /* Subroutines of life analysis. */
1405 /* Allocate the permanent data structures that represent the results
1406 of life analysis. */
1409 allocate_bb_life_data (void)
1413 FOR_BB_BETWEEN (bb
, ENTRY_BLOCK_PTR
, NULL
, next_bb
)
1415 bb
->global_live_at_start
= OBSTACK_ALLOC_REG_SET (&flow_obstack
);
1416 bb
->global_live_at_end
= OBSTACK_ALLOC_REG_SET (&flow_obstack
);
1419 regs_live_at_setjmp
= OBSTACK_ALLOC_REG_SET (&flow_obstack
);
1423 allocate_reg_life_data (void)
1427 max_regno
= max_reg_num ();
1428 gcc_assert (!reg_deaths
);
1429 reg_deaths
= xcalloc (sizeof (*reg_deaths
), max_regno
);
1431 /* Recalculate the register space, in case it has grown. Old style
1432 vector oriented regsets would set regset_{size,bytes} here also. */
1433 allocate_reg_info (max_regno
, FALSE
, FALSE
);
1435 /* Reset all the data we'll collect in propagate_block and its
1437 for (i
= 0; i
< max_regno
; i
++)
1441 REG_N_DEATHS (i
) = 0;
1442 REG_N_CALLS_CROSSED (i
) = 0;
1443 REG_LIVE_LENGTH (i
) = 0;
1445 REG_BASIC_BLOCK (i
) = REG_BLOCK_UNKNOWN
;
1449 /* Delete dead instructions for propagate_block. */
1452 propagate_block_delete_insn (rtx insn
)
1454 rtx inote
= find_reg_note (insn
, REG_LABEL
, NULL_RTX
);
1456 /* If the insn referred to a label, and that label was attached to
1457 an ADDR_VEC, it's safe to delete the ADDR_VEC. In fact, it's
1458 pretty much mandatory to delete it, because the ADDR_VEC may be
1459 referencing labels that no longer exist.
1461 INSN may reference a deleted label, particularly when a jump
1462 table has been optimized into a direct jump. There's no
1463 real good way to fix up the reference to the deleted label
1464 when the label is deleted, so we just allow it here. */
1466 if (inote
&& LABEL_P (inote
))
1468 rtx label
= XEXP (inote
, 0);
1471 /* The label may be forced if it has been put in the constant
1472 pool. If that is the only use we must discard the table
1473 jump following it, but not the label itself. */
1474 if (LABEL_NUSES (label
) == 1 + LABEL_PRESERVE_P (label
)
1475 && (next
= next_nonnote_insn (label
)) != NULL
1477 && (GET_CODE (PATTERN (next
)) == ADDR_VEC
1478 || GET_CODE (PATTERN (next
)) == ADDR_DIFF_VEC
))
1480 rtx pat
= PATTERN (next
);
1481 int diff_vec_p
= GET_CODE (pat
) == ADDR_DIFF_VEC
;
1482 int len
= XVECLEN (pat
, diff_vec_p
);
1485 for (i
= 0; i
< len
; i
++)
1486 LABEL_NUSES (XEXP (XVECEXP (pat
, diff_vec_p
, i
), 0))--;
1488 delete_insn_and_edges (next
);
1493 delete_insn_and_edges (insn
);
1497 /* Delete dead libcalls for propagate_block. Return the insn
1498 before the libcall. */
1501 propagate_block_delete_libcall (rtx insn
, rtx note
)
1503 rtx first
= XEXP (note
, 0);
1504 rtx before
= PREV_INSN (first
);
1506 delete_insn_chain_and_edges (first
, insn
);
1511 /* Update the life-status of regs for one insn. Return the previous insn. */
1514 propagate_one_insn (struct propagate_block_info
*pbi
, rtx insn
)
1516 rtx prev
= PREV_INSN (insn
);
1517 int flags
= pbi
->flags
;
1518 int insn_is_dead
= 0;
1519 int libcall_is_dead
= 0;
1523 if (! INSN_P (insn
))
1526 note
= find_reg_note (insn
, REG_RETVAL
, NULL_RTX
);
1527 if (flags
& PROP_SCAN_DEAD_CODE
)
1529 insn_is_dead
= insn_dead_p (pbi
, PATTERN (insn
), 0, REG_NOTES (insn
));
1530 libcall_is_dead
= (insn_is_dead
&& note
!= 0
1531 && libcall_dead_p (pbi
, note
, insn
));
1534 /* If an instruction consists of just dead store(s) on final pass,
1536 if ((flags
& PROP_KILL_DEAD_CODE
) && insn_is_dead
)
1538 /* If we're trying to delete a prologue or epilogue instruction
1539 that isn't flagged as possibly being dead, something is wrong.
1540 But if we are keeping the stack pointer depressed, we might well
1541 be deleting insns that are used to compute the amount to update
1542 it by, so they are fine. */
1543 if (reload_completed
1544 && !(TREE_CODE (TREE_TYPE (current_function_decl
)) == FUNCTION_TYPE
1545 && (TYPE_RETURNS_STACK_DEPRESSED
1546 (TREE_TYPE (current_function_decl
))))
1547 && (((HAVE_epilogue
|| HAVE_prologue
)
1548 && prologue_epilogue_contains (insn
))
1549 || (HAVE_sibcall_epilogue
1550 && sibcall_epilogue_contains (insn
)))
1551 && find_reg_note (insn
, REG_MAYBE_DEAD
, NULL_RTX
) == 0)
1552 fatal_insn ("Attempt to delete prologue/epilogue insn:", insn
);
1554 /* Record sets. Do this even for dead instructions, since they
1555 would have killed the values if they hadn't been deleted. */
1556 mark_set_regs (pbi
, PATTERN (insn
), insn
);
1558 /* CC0 is now known to be dead. Either this insn used it,
1559 in which case it doesn't anymore, or clobbered it,
1560 so the next insn can't use it. */
1563 if (libcall_is_dead
)
1564 prev
= propagate_block_delete_libcall ( insn
, note
);
1568 /* If INSN contains a RETVAL note and is dead, but the libcall
1569 as a whole is not dead, then we want to remove INSN, but
1570 not the whole libcall sequence.
1572 However, we need to also remove the dangling REG_LIBCALL
1573 note so that we do not have mis-matched LIBCALL/RETVAL
1574 notes. In theory we could find a new location for the
1575 REG_RETVAL note, but it hardly seems worth the effort.
1577 NOTE at this point will be the RETVAL note if it exists. */
1583 = find_reg_note (XEXP (note
, 0), REG_LIBCALL
, NULL_RTX
);
1584 remove_note (XEXP (note
, 0), libcall_note
);
1587 /* Similarly if INSN contains a LIBCALL note, remove the
1588 dangling REG_RETVAL note. */
1589 note
= find_reg_note (insn
, REG_LIBCALL
, NULL_RTX
);
1595 = find_reg_note (XEXP (note
, 0), REG_RETVAL
, NULL_RTX
);
1596 remove_note (XEXP (note
, 0), retval_note
);
1599 /* Now delete INSN. */
1600 propagate_block_delete_insn (insn
);
1606 /* See if this is an increment or decrement that can be merged into
1607 a following memory address. */
1610 rtx x
= single_set (insn
);
1612 /* Does this instruction increment or decrement a register? */
1613 if ((flags
& PROP_AUTOINC
)
1615 && REG_P (SET_DEST (x
))
1616 && (GET_CODE (SET_SRC (x
)) == PLUS
1617 || GET_CODE (SET_SRC (x
)) == MINUS
)
1618 && XEXP (SET_SRC (x
), 0) == SET_DEST (x
)
1619 && GET_CODE (XEXP (SET_SRC (x
), 1)) == CONST_INT
1620 /* Ok, look for a following memory ref we can combine with.
1621 If one is found, change the memory ref to a PRE_INC
1622 or PRE_DEC, cancel this insn, and return 1.
1623 Return 0 if nothing has been done. */
1624 && try_pre_increment_1 (pbi
, insn
))
1627 #endif /* AUTO_INC_DEC */
1629 CLEAR_REG_SET (pbi
->new_set
);
1631 /* If this is not the final pass, and this insn is copying the value of
1632 a library call and it's dead, don't scan the insns that perform the
1633 library call, so that the call's arguments are not marked live. */
1634 if (libcall_is_dead
)
1636 /* Record the death of the dest reg. */
1637 mark_set_regs (pbi
, PATTERN (insn
), insn
);
1639 insn
= XEXP (note
, 0);
1640 return PREV_INSN (insn
);
1642 else if (GET_CODE (PATTERN (insn
)) == SET
1643 && SET_DEST (PATTERN (insn
)) == stack_pointer_rtx
1644 && GET_CODE (SET_SRC (PATTERN (insn
))) == PLUS
1645 && XEXP (SET_SRC (PATTERN (insn
)), 0) == stack_pointer_rtx
1646 && GET_CODE (XEXP (SET_SRC (PATTERN (insn
)), 1)) == CONST_INT
)
1648 /* We have an insn to pop a constant amount off the stack.
1649 (Such insns use PLUS regardless of the direction of the stack,
1650 and any insn to adjust the stack by a constant is always a pop
1652 These insns, if not dead stores, have no effect on life, though
1653 they do have an effect on the memory stores we are tracking. */
1654 invalidate_mems_from_set (pbi
, stack_pointer_rtx
);
1655 /* Still, we need to update local_set, lest ifcvt.c:dead_or_predicable
1656 concludes that the stack pointer is not modified. */
1657 mark_set_regs (pbi
, PATTERN (insn
), insn
);
1662 /* Any regs live at the time of a call instruction must not go
1663 in a register clobbered by calls. Find all regs now live and
1664 record this for them. */
1666 if (CALL_P (insn
) && (flags
& PROP_REG_INFO
))
1668 reg_set_iterator rsi
;
1669 EXECUTE_IF_SET_IN_REG_SET (pbi
->reg_live
, 0, i
, rsi
)
1670 REG_N_CALLS_CROSSED (i
)++;
1673 /* Record sets. Do this even for dead instructions, since they
1674 would have killed the values if they hadn't been deleted. */
1675 mark_set_regs (pbi
, PATTERN (insn
), insn
);
1685 if (GET_CODE (PATTERN (insn
)) == COND_EXEC
)
1686 cond
= COND_EXEC_TEST (PATTERN (insn
));
1688 /* Non-constant calls clobber memory, constant calls do not
1689 clobber memory, though they may clobber outgoing arguments
1691 if (! CONST_OR_PURE_CALL_P (insn
))
1693 free_EXPR_LIST_list (&pbi
->mem_set_list
);
1694 pbi
->mem_set_list_len
= 0;
1697 invalidate_mems_from_set (pbi
, stack_pointer_rtx
);
1699 /* There may be extra registers to be clobbered. */
1700 for (note
= CALL_INSN_FUNCTION_USAGE (insn
);
1702 note
= XEXP (note
, 1))
1703 if (GET_CODE (XEXP (note
, 0)) == CLOBBER
)
1704 mark_set_1 (pbi
, CLOBBER
, XEXP (XEXP (note
, 0), 0),
1705 cond
, insn
, pbi
->flags
);
1707 /* Calls change all call-used and global registers; sibcalls do not
1708 clobber anything that must be preserved at end-of-function,
1709 except for return values. */
1711 sibcall_p
= SIBLING_CALL_P (insn
);
1712 live_at_end
= EXIT_BLOCK_PTR
->global_live_at_start
;
1713 for (i
= 0; i
< FIRST_PSEUDO_REGISTER
; i
++)
1714 if (TEST_HARD_REG_BIT (regs_invalidated_by_call
, i
)
1716 && REGNO_REG_SET_P (live_at_end
, i
)
1717 && ! refers_to_regno_p (i
, i
+1,
1718 current_function_return_rtx
,
1721 enum rtx_code code
= global_regs
[i
] ? SET
: CLOBBER
;
1722 /* We do not want REG_UNUSED notes for these registers. */
1723 mark_set_1 (pbi
, code
, regno_reg_rtx
[i
], cond
, insn
,
1724 pbi
->flags
& ~(PROP_DEATH_NOTES
| PROP_REG_INFO
));
1728 /* If an insn doesn't use CC0, it becomes dead since we assume
1729 that every insn clobbers it. So show it dead here;
1730 mark_used_regs will set it live if it is referenced. */
1735 mark_used_regs (pbi
, PATTERN (insn
), NULL_RTX
, insn
);
1736 if ((flags
& PROP_EQUAL_NOTES
)
1737 && ((note
= find_reg_note (insn
, REG_EQUAL
, NULL_RTX
))
1738 || (note
= find_reg_note (insn
, REG_EQUIV
, NULL_RTX
))))
1739 mark_used_regs (pbi
, XEXP (note
, 0), NULL_RTX
, insn
);
1741 /* Sometimes we may have inserted something before INSN (such as a move)
1742 when we make an auto-inc. So ensure we will scan those insns. */
1744 prev
= PREV_INSN (insn
);
1747 if (! insn_is_dead
&& CALL_P (insn
))
1753 if (GET_CODE (PATTERN (insn
)) == COND_EXEC
)
1754 cond
= COND_EXEC_TEST (PATTERN (insn
));
1756 /* Calls use their arguments, and may clobber memory which
1757 address involves some register. */
1758 for (note
= CALL_INSN_FUNCTION_USAGE (insn
);
1760 note
= XEXP (note
, 1))
1761 /* We find USE or CLOBBER entities in a FUNCTION_USAGE list: both
1762 of which mark_used_regs knows how to handle. */
1763 mark_used_regs (pbi
, XEXP (XEXP (note
, 0), 0), cond
, insn
);
1765 /* The stack ptr is used (honorarily) by a CALL insn. */
1766 if ((flags
& PROP_REG_INFO
)
1767 && !REGNO_REG_SET_P (pbi
->reg_live
, STACK_POINTER_REGNUM
))
1768 reg_deaths
[STACK_POINTER_REGNUM
] = pbi
->insn_num
;
1769 SET_REGNO_REG_SET (pbi
->reg_live
, STACK_POINTER_REGNUM
);
1771 /* Calls may also reference any of the global registers,
1772 so they are made live. */
1773 for (i
= 0; i
< FIRST_PSEUDO_REGISTER
; i
++)
1775 mark_used_reg (pbi
, regno_reg_rtx
[i
], cond
, insn
);
1784 /* Initialize a propagate_block_info struct for public consumption.
1785 Note that the structure itself is opaque to this file, but that
1786 the user can use the regsets provided here. */
1788 struct propagate_block_info
*
1789 init_propagate_block_info (basic_block bb
, regset live
, regset local_set
,
1790 regset cond_local_set
, int flags
)
1792 struct propagate_block_info
*pbi
= xmalloc (sizeof (*pbi
));
1795 pbi
->reg_live
= live
;
1796 pbi
->mem_set_list
= NULL_RTX
;
1797 pbi
->mem_set_list_len
= 0;
1798 pbi
->local_set
= local_set
;
1799 pbi
->cond_local_set
= cond_local_set
;
1804 if (flags
& (PROP_LOG_LINKS
| PROP_AUTOINC
))
1805 pbi
->reg_next_use
= xcalloc (max_reg_num (), sizeof (rtx
));
1807 pbi
->reg_next_use
= NULL
;
1809 pbi
->new_set
= BITMAP_XMALLOC ();
1811 #ifdef HAVE_conditional_execution
1812 pbi
->reg_cond_dead
= splay_tree_new (splay_tree_compare_ints
, NULL
,
1813 free_reg_cond_life_info
);
1814 pbi
->reg_cond_reg
= BITMAP_XMALLOC ();
1816 /* If this block ends in a conditional branch, for each register
1817 live from one side of the branch and not the other, record the
1818 register as conditionally dead. */
1819 if (JUMP_P (BB_END (bb
))
1820 && any_condjump_p (BB_END (bb
)))
1822 regset_head diff_head
;
1823 regset diff
= INITIALIZE_REG_SET (diff_head
);
1824 basic_block bb_true
, bb_false
;
1827 /* Identify the successor blocks. */
1828 bb_true
= EDGE_SUCC (bb
, 0)->dest
;
1829 if (EDGE_COUNT (bb
->succs
) > 1)
1831 bb_false
= EDGE_SUCC (bb
, 1)->dest
;
1833 if (EDGE_SUCC (bb
, 0)->flags
& EDGE_FALLTHRU
)
1835 basic_block t
= bb_false
;
1840 gcc_assert (EDGE_SUCC (bb
, 1)->flags
& EDGE_FALLTHRU
);
1844 /* This can happen with a conditional jump to the next insn. */
1845 gcc_assert (JUMP_LABEL (BB_END (bb
)) == BB_HEAD (bb_true
));
1847 /* Simplest way to do nothing. */
1851 /* Compute which register lead different lives in the successors. */
1852 bitmap_xor (diff
, bb_true
->global_live_at_start
,
1853 bb_false
->global_live_at_start
);
1855 if (!bitmap_empty_p (diff
))
1857 /* Extract the condition from the branch. */
1858 rtx set_src
= SET_SRC (pc_set (BB_END (bb
)));
1859 rtx cond_true
= XEXP (set_src
, 0);
1860 rtx reg
= XEXP (cond_true
, 0);
1861 enum rtx_code inv_cond
;
1863 if (GET_CODE (reg
) == SUBREG
)
1864 reg
= SUBREG_REG (reg
);
1866 /* We can only track conditional lifetimes if the condition is
1867 in the form of a reversible comparison of a register against
1868 zero. If the condition is more complex than that, then it is
1869 safe not to record any information. */
1870 inv_cond
= reversed_comparison_code (cond_true
, BB_END (bb
));
1871 if (inv_cond
!= UNKNOWN
1873 && XEXP (cond_true
, 1) == const0_rtx
)
1876 = gen_rtx_fmt_ee (inv_cond
,
1877 GET_MODE (cond_true
), XEXP (cond_true
, 0),
1878 XEXP (cond_true
, 1));
1879 reg_set_iterator rsi
;
1881 if (GET_CODE (XEXP (set_src
, 1)) == PC
)
1884 cond_false
= cond_true
;
1888 SET_REGNO_REG_SET (pbi
->reg_cond_reg
, REGNO (reg
));
1890 /* For each such register, mark it conditionally dead. */
1891 EXECUTE_IF_SET_IN_REG_SET (diff
, 0, i
, rsi
)
1893 struct reg_cond_life_info
*rcli
;
1896 rcli
= xmalloc (sizeof (*rcli
));
1898 if (REGNO_REG_SET_P (bb_true
->global_live_at_start
, i
))
1902 rcli
->condition
= cond
;
1903 rcli
->stores
= const0_rtx
;
1904 rcli
->orig_condition
= cond
;
1906 splay_tree_insert (pbi
->reg_cond_dead
, i
,
1907 (splay_tree_value
) rcli
);
1912 FREE_REG_SET (diff
);
1916 /* If this block has no successors, any stores to the frame that aren't
1917 used later in the block are dead. So make a pass over the block
1918 recording any such that are made and show them dead at the end. We do
1919 a very conservative and simple job here. */
1921 && ! (TREE_CODE (TREE_TYPE (current_function_decl
)) == FUNCTION_TYPE
1922 && (TYPE_RETURNS_STACK_DEPRESSED
1923 (TREE_TYPE (current_function_decl
))))
1924 && (flags
& PROP_SCAN_DEAD_STORES
)
1925 && (EDGE_COUNT (bb
->succs
) == 0
1926 || (EDGE_COUNT (bb
->succs
) == 1
1927 && EDGE_SUCC (bb
, 0)->dest
== EXIT_BLOCK_PTR
1928 && ! current_function_calls_eh_return
)))
1931 for (insn
= BB_END (bb
); insn
!= BB_HEAD (bb
); insn
= PREV_INSN (insn
))
1932 if (NONJUMP_INSN_P (insn
)
1933 && (set
= single_set (insn
))
1934 && MEM_P (SET_DEST (set
)))
1936 rtx mem
= SET_DEST (set
);
1937 rtx canon_mem
= canon_rtx (mem
);
1939 if (XEXP (canon_mem
, 0) == frame_pointer_rtx
1940 || (GET_CODE (XEXP (canon_mem
, 0)) == PLUS
1941 && XEXP (XEXP (canon_mem
, 0), 0) == frame_pointer_rtx
1942 && GET_CODE (XEXP (XEXP (canon_mem
, 0), 1)) == CONST_INT
))
1943 add_to_mem_set_list (pbi
, canon_mem
);
1950 /* Release a propagate_block_info struct. */
1953 free_propagate_block_info (struct propagate_block_info
*pbi
)
1955 free_EXPR_LIST_list (&pbi
->mem_set_list
);
1957 BITMAP_XFREE (pbi
->new_set
);
1959 #ifdef HAVE_conditional_execution
1960 splay_tree_delete (pbi
->reg_cond_dead
);
1961 BITMAP_XFREE (pbi
->reg_cond_reg
);
1964 if (pbi
->flags
& PROP_REG_INFO
)
1966 int num
= pbi
->insn_num
;
1968 reg_set_iterator rsi
;
1970 EXECUTE_IF_SET_IN_REG_SET (pbi
->reg_live
, 0, i
, rsi
)
1972 REG_LIVE_LENGTH (i
) += num
- reg_deaths
[i
];
1976 if (pbi
->reg_next_use
)
1977 free (pbi
->reg_next_use
);
1982 /* Compute the registers live at the beginning of a basic block BB from
1983 those live at the end.
1985 When called, REG_LIVE contains those live at the end. On return, it
1986 contains those live at the beginning.
1988 LOCAL_SET, if non-null, will be set with all registers killed
1989 unconditionally by this basic block.
1990 Likewise, COND_LOCAL_SET, if non-null, will be set with all registers
1991 killed conditionally by this basic block. If there is any unconditional
1992 set of a register, then the corresponding bit will be set in LOCAL_SET
1993 and cleared in COND_LOCAL_SET.
1994 It is valid for LOCAL_SET and COND_LOCAL_SET to be the same set. In this
1995 case, the resulting set will be equal to the union of the two sets that
1996 would otherwise be computed.
1998 Return nonzero if an INSN is deleted (i.e. by dead code removal). */
2001 propagate_block (basic_block bb
, regset live
, regset local_set
,
2002 regset cond_local_set
, int flags
)
2004 struct propagate_block_info
*pbi
;
2008 pbi
= init_propagate_block_info (bb
, live
, local_set
, cond_local_set
, flags
);
2010 if (flags
& PROP_REG_INFO
)
2013 reg_set_iterator rsi
;
2015 /* Process the regs live at the end of the block.
2016 Mark them as not local to any one basic block. */
2017 EXECUTE_IF_SET_IN_REG_SET (live
, 0, i
, rsi
)
2018 REG_BASIC_BLOCK (i
) = REG_BLOCK_GLOBAL
;
2021 /* Scan the block an insn at a time from end to beginning. */
2024 for (insn
= BB_END (bb
); ; insn
= prev
)
2026 /* If this is a call to `setjmp' et al, warn if any
2027 non-volatile datum is live. */
2028 if ((flags
& PROP_REG_INFO
)
2030 && find_reg_note (insn
, REG_SETJMP
, NULL
))
2031 IOR_REG_SET (regs_live_at_setjmp
, pbi
->reg_live
);
2033 prev
= propagate_one_insn (pbi
, insn
);
2035 changed
|= insn
!= get_insns ();
2037 changed
|= NEXT_INSN (prev
) != insn
;
2039 if (insn
== BB_HEAD (bb
))
2043 free_propagate_block_info (pbi
);
2048 /* Return 1 if X (the body of an insn, or part of it) is just dead stores
2049 (SET expressions whose destinations are registers dead after the insn).
2050 NEEDED is the regset that says which regs are alive after the insn.
2052 Unless CALL_OK is nonzero, an insn is needed if it contains a CALL.
2054 If X is the entire body of an insn, NOTES contains the reg notes
2055 pertaining to the insn. */
2058 insn_dead_p (struct propagate_block_info
*pbi
, rtx x
, int call_ok
,
2059 rtx notes ATTRIBUTE_UNUSED
)
2061 enum rtx_code code
= GET_CODE (x
);
2063 /* Don't eliminate insns that may trap. */
2064 if (flag_non_call_exceptions
&& may_trap_p (x
))
2068 /* As flow is invoked after combine, we must take existing AUTO_INC
2069 expressions into account. */
2070 for (; notes
; notes
= XEXP (notes
, 1))
2072 if (REG_NOTE_KIND (notes
) == REG_INC
)
2074 int regno
= REGNO (XEXP (notes
, 0));
2076 /* Don't delete insns to set global regs. */
2077 if ((regno
< FIRST_PSEUDO_REGISTER
&& global_regs
[regno
])
2078 || REGNO_REG_SET_P (pbi
->reg_live
, regno
))
2084 /* If setting something that's a reg or part of one,
2085 see if that register's altered value will be live. */
2089 rtx r
= SET_DEST (x
);
2092 if (GET_CODE (r
) == CC0
)
2093 return ! pbi
->cc0_live
;
2096 /* A SET that is a subroutine call cannot be dead. */
2097 if (GET_CODE (SET_SRC (x
)) == CALL
)
2103 /* Don't eliminate loads from volatile memory or volatile asms. */
2104 else if (volatile_refs_p (SET_SRC (x
)))
2111 if (MEM_VOLATILE_P (r
) || GET_MODE (r
) == BLKmode
)
2114 canon_r
= canon_rtx (r
);
2116 /* Walk the set of memory locations we are currently tracking
2117 and see if one is an identical match to this memory location.
2118 If so, this memory write is dead (remember, we're walking
2119 backwards from the end of the block to the start). Since
2120 rtx_equal_p does not check the alias set or flags, we also
2121 must have the potential for them to conflict (anti_dependence). */
2122 for (temp
= pbi
->mem_set_list
; temp
!= 0; temp
= XEXP (temp
, 1))
2123 if (anti_dependence (r
, XEXP (temp
, 0)))
2125 rtx mem
= XEXP (temp
, 0);
2127 if (rtx_equal_p (XEXP (canon_r
, 0), XEXP (mem
, 0))
2128 && (GET_MODE_SIZE (GET_MODE (canon_r
))
2129 <= GET_MODE_SIZE (GET_MODE (mem
))))
2133 /* Check if memory reference matches an auto increment. Only
2134 post increment/decrement or modify are valid. */
2135 if (GET_MODE (mem
) == GET_MODE (r
)
2136 && (GET_CODE (XEXP (mem
, 0)) == POST_DEC
2137 || GET_CODE (XEXP (mem
, 0)) == POST_INC
2138 || GET_CODE (XEXP (mem
, 0)) == POST_MODIFY
)
2139 && GET_MODE (XEXP (mem
, 0)) == GET_MODE (r
)
2140 && rtx_equal_p (XEXP (XEXP (mem
, 0), 0), XEXP (r
, 0)))
2147 while (GET_CODE (r
) == SUBREG
2148 || GET_CODE (r
) == STRICT_LOW_PART
2149 || GET_CODE (r
) == ZERO_EXTRACT
)
2154 int regno
= REGNO (r
);
2157 if (REGNO_REG_SET_P (pbi
->reg_live
, regno
))
2160 /* If this is a hard register, verify that subsequent
2161 words are not needed. */
2162 if (regno
< FIRST_PSEUDO_REGISTER
)
2164 int n
= hard_regno_nregs
[regno
][GET_MODE (r
)];
2167 if (REGNO_REG_SET_P (pbi
->reg_live
, regno
+n
))
2171 /* Don't delete insns to set global regs. */
2172 if (regno
< FIRST_PSEUDO_REGISTER
&& global_regs
[regno
])
2175 /* Make sure insns to set the stack pointer aren't deleted. */
2176 if (regno
== STACK_POINTER_REGNUM
)
2179 /* ??? These bits might be redundant with the force live bits
2180 in calculate_global_regs_live. We would delete from
2181 sequential sets; whether this actually affects real code
2182 for anything but the stack pointer I don't know. */
2183 /* Make sure insns to set the frame pointer aren't deleted. */
2184 if (regno
== FRAME_POINTER_REGNUM
2185 && (! reload_completed
|| frame_pointer_needed
))
2187 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
2188 if (regno
== HARD_FRAME_POINTER_REGNUM
2189 && (! reload_completed
|| frame_pointer_needed
))
2193 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
2194 /* Make sure insns to set arg pointer are never deleted
2195 (if the arg pointer isn't fixed, there will be a USE
2196 for it, so we can treat it normally). */
2197 if (regno
== ARG_POINTER_REGNUM
&& fixed_regs
[regno
])
2201 /* Otherwise, the set is dead. */
2207 /* If performing several activities, insn is dead if each activity
2208 is individually dead. Also, CLOBBERs and USEs can be ignored; a
2209 CLOBBER or USE that's inside a PARALLEL doesn't make the insn
2211 else if (code
== PARALLEL
)
2213 int i
= XVECLEN (x
, 0);
2215 for (i
--; i
>= 0; i
--)
2216 if (GET_CODE (XVECEXP (x
, 0, i
)) != CLOBBER
2217 && GET_CODE (XVECEXP (x
, 0, i
)) != USE
2218 && ! insn_dead_p (pbi
, XVECEXP (x
, 0, i
), call_ok
, NULL_RTX
))
2224 /* A CLOBBER of a pseudo-register that is dead serves no purpose. That
2225 is not necessarily true for hard registers until after reload. */
2226 else if (code
== CLOBBER
)
2228 if (REG_P (XEXP (x
, 0))
2229 && (REGNO (XEXP (x
, 0)) >= FIRST_PSEUDO_REGISTER
2230 || reload_completed
)
2231 && ! REGNO_REG_SET_P (pbi
->reg_live
, REGNO (XEXP (x
, 0))))
2235 /* ??? A base USE is a historical relic. It ought not be needed anymore.
2236 Instances where it is still used are either (1) temporary and the USE
2237 escaped the pass, (2) cruft and the USE need not be emitted anymore,
2238 or (3) hiding bugs elsewhere that are not properly representing data
2244 /* If INSN is the last insn in a libcall, and assuming INSN is dead,
2245 return 1 if the entire library call is dead.
2246 This is true if INSN copies a register (hard or pseudo)
2247 and if the hard return reg of the call insn is dead.
2248 (The caller should have tested the destination of the SET inside
2249 INSN already for death.)
2251 If this insn doesn't just copy a register, then we don't
2252 have an ordinary libcall. In that case, cse could not have
2253 managed to substitute the source for the dest later on,
2254 so we can assume the libcall is dead.
2256 PBI is the block info giving pseudoregs live before this insn.
2257 NOTE is the REG_RETVAL note of the insn. */
2260 libcall_dead_p (struct propagate_block_info
*pbi
, rtx note
, rtx insn
)
2262 rtx x
= single_set (insn
);
2266 rtx r
= SET_SRC (x
);
2270 rtx call
= XEXP (note
, 0);
2274 /* Find the call insn. */
2275 while (call
!= insn
&& !CALL_P (call
))
2276 call
= NEXT_INSN (call
);
2278 /* If there is none, do nothing special,
2279 since ordinary death handling can understand these insns. */
2283 /* See if the hard reg holding the value is dead.
2284 If this is a PARALLEL, find the call within it. */
2285 call_pat
= PATTERN (call
);
2286 if (GET_CODE (call_pat
) == PARALLEL
)
2288 for (i
= XVECLEN (call_pat
, 0) - 1; i
>= 0; i
--)
2289 if (GET_CODE (XVECEXP (call_pat
, 0, i
)) == SET
2290 && GET_CODE (SET_SRC (XVECEXP (call_pat
, 0, i
))) == CALL
)
2293 /* This may be a library call that is returning a value
2294 via invisible pointer. Do nothing special, since
2295 ordinary death handling can understand these insns. */
2299 call_pat
= XVECEXP (call_pat
, 0, i
);
2302 return insn_dead_p (pbi
, call_pat
, 1, REG_NOTES (call
));
2308 /* 1 if register REGNO was alive at a place where `setjmp' was called
2309 and was set more than once or is an argument.
2310 Such regs may be clobbered by `longjmp'. */
2313 regno_clobbered_at_setjmp (int regno
)
2315 if (n_basic_blocks
== 0)
2318 return ((REG_N_SETS (regno
) > 1
2319 || REGNO_REG_SET_P (ENTRY_BLOCK_PTR
->global_live_at_end
, regno
))
2320 && REGNO_REG_SET_P (regs_live_at_setjmp
, regno
));
2323 /* Add MEM to PBI->MEM_SET_LIST. MEM should be canonical. Respect the
2324 maximal list size; look for overlaps in mode and select the largest. */
2326 add_to_mem_set_list (struct propagate_block_info
*pbi
, rtx mem
)
2330 /* We don't know how large a BLKmode store is, so we must not
2331 take them into consideration. */
2332 if (GET_MODE (mem
) == BLKmode
)
2335 for (i
= pbi
->mem_set_list
; i
; i
= XEXP (i
, 1))
2337 rtx e
= XEXP (i
, 0);
2338 if (rtx_equal_p (XEXP (mem
, 0), XEXP (e
, 0)))
2340 if (GET_MODE_SIZE (GET_MODE (mem
)) > GET_MODE_SIZE (GET_MODE (e
)))
2343 /* If we must store a copy of the mem, we can just modify
2344 the mode of the stored copy. */
2345 if (pbi
->flags
& PROP_AUTOINC
)
2346 PUT_MODE (e
, GET_MODE (mem
));
2355 if (pbi
->mem_set_list_len
< MAX_MEM_SET_LIST_LEN
)
2358 /* Store a copy of mem, otherwise the address may be
2359 scrogged by find_auto_inc. */
2360 if (pbi
->flags
& PROP_AUTOINC
)
2361 mem
= shallow_copy_rtx (mem
);
2363 pbi
->mem_set_list
= alloc_EXPR_LIST (0, mem
, pbi
->mem_set_list
);
2364 pbi
->mem_set_list_len
++;
2368 /* INSN references memory, possibly using autoincrement addressing modes.
2369 Find any entries on the mem_set_list that need to be invalidated due
2370 to an address change. */
2373 invalidate_mems_from_autoinc (rtx
*px
, void *data
)
2376 struct propagate_block_info
*pbi
= data
;
2378 if (GET_RTX_CLASS (GET_CODE (x
)) == RTX_AUTOINC
)
2380 invalidate_mems_from_set (pbi
, XEXP (x
, 0));
2387 /* EXP is a REG. Remove any dependent entries from pbi->mem_set_list. */
2390 invalidate_mems_from_set (struct propagate_block_info
*pbi
, rtx exp
)
2392 rtx temp
= pbi
->mem_set_list
;
2393 rtx prev
= NULL_RTX
;
2398 next
= XEXP (temp
, 1);
2399 if (reg_overlap_mentioned_p (exp
, XEXP (temp
, 0)))
2401 /* Splice this entry out of the list. */
2403 XEXP (prev
, 1) = next
;
2405 pbi
->mem_set_list
= next
;
2406 free_EXPR_LIST_node (temp
);
2407 pbi
->mem_set_list_len
--;
2415 /* Process the registers that are set within X. Their bits are set to
2416 1 in the regset DEAD, because they are dead prior to this insn.
2418 If INSN is nonzero, it is the insn being processed.
2420 FLAGS is the set of operations to perform. */
2423 mark_set_regs (struct propagate_block_info
*pbi
, rtx x
, rtx insn
)
2425 rtx cond
= NULL_RTX
;
2428 int flags
= pbi
->flags
;
2431 for (link
= REG_NOTES (insn
); link
; link
= XEXP (link
, 1))
2433 if (REG_NOTE_KIND (link
) == REG_INC
)
2434 mark_set_1 (pbi
, SET
, XEXP (link
, 0),
2435 (GET_CODE (x
) == COND_EXEC
2436 ? COND_EXEC_TEST (x
) : NULL_RTX
),
2440 switch (code
= GET_CODE (x
))
2443 if (GET_CODE (XEXP (x
, 1)) == ASM_OPERANDS
)
2444 flags
|= PROP_ASM_SCAN
;
2447 mark_set_1 (pbi
, code
, SET_DEST (x
), cond
, insn
, flags
);
2451 cond
= COND_EXEC_TEST (x
);
2452 x
= COND_EXEC_CODE (x
);
2459 /* We must scan forwards. If we have an asm, we need to set
2460 the PROP_ASM_SCAN flag before scanning the clobbers. */
2461 for (i
= 0; i
< XVECLEN (x
, 0); i
++)
2463 rtx sub
= XVECEXP (x
, 0, i
);
2464 switch (code
= GET_CODE (sub
))
2469 cond
= COND_EXEC_TEST (sub
);
2470 sub
= COND_EXEC_CODE (sub
);
2471 if (GET_CODE (sub
) == SET
)
2473 if (GET_CODE (sub
) == CLOBBER
)
2479 if (GET_CODE (XEXP (sub
, 1)) == ASM_OPERANDS
)
2480 flags
|= PROP_ASM_SCAN
;
2484 mark_set_1 (pbi
, code
, SET_DEST (sub
), cond
, insn
, flags
);
2488 flags
|= PROP_ASM_SCAN
;
2503 /* Process a single set, which appears in INSN. REG (which may not
2504 actually be a REG, it may also be a SUBREG, PARALLEL, etc.) is
2505 being set using the CODE (which may be SET, CLOBBER, or COND_EXEC).
2506 If the set is conditional (because it appear in a COND_EXEC), COND
2507 will be the condition. */
2510 mark_set_1 (struct propagate_block_info
*pbi
, enum rtx_code code
, rtx reg
, rtx cond
, rtx insn
, int flags
)
2512 int regno_first
= -1, regno_last
= -1;
2513 unsigned long not_dead
= 0;
2516 /* Modifying just one hardware register of a multi-reg value or just a
2517 byte field of a register does not mean the value from before this insn
2518 is now dead. Of course, if it was dead after it's unused now. */
2520 switch (GET_CODE (reg
))
2523 /* Some targets place small structures in registers for return values of
2524 functions. We have to detect this case specially here to get correct
2525 flow information. */
2526 for (i
= XVECLEN (reg
, 0) - 1; i
>= 0; i
--)
2527 if (XEXP (XVECEXP (reg
, 0, i
), 0) != 0)
2528 mark_set_1 (pbi
, code
, XEXP (XVECEXP (reg
, 0, i
), 0), cond
, insn
,
2534 case STRICT_LOW_PART
:
2535 /* ??? Assumes STRICT_LOW_PART not used on multi-word registers. */
2537 reg
= XEXP (reg
, 0);
2538 while (GET_CODE (reg
) == SUBREG
2539 || GET_CODE (reg
) == ZERO_EXTRACT
2540 || GET_CODE (reg
) == SIGN_EXTRACT
2541 || GET_CODE (reg
) == STRICT_LOW_PART
);
2544 not_dead
= (unsigned long) REGNO_REG_SET_P (pbi
->reg_live
, REGNO (reg
));
2548 regno_last
= regno_first
= REGNO (reg
);
2549 if (regno_first
< FIRST_PSEUDO_REGISTER
)
2550 regno_last
+= hard_regno_nregs
[regno_first
][GET_MODE (reg
)] - 1;
2554 if (REG_P (SUBREG_REG (reg
)))
2556 enum machine_mode outer_mode
= GET_MODE (reg
);
2557 enum machine_mode inner_mode
= GET_MODE (SUBREG_REG (reg
));
2559 /* Identify the range of registers affected. This is moderately
2560 tricky for hard registers. See alter_subreg. */
2562 regno_last
= regno_first
= REGNO (SUBREG_REG (reg
));
2563 if (regno_first
< FIRST_PSEUDO_REGISTER
)
2565 regno_first
+= subreg_regno_offset (regno_first
, inner_mode
,
2568 regno_last
= (regno_first
2569 + hard_regno_nregs
[regno_first
][outer_mode
] - 1);
2571 /* Since we've just adjusted the register number ranges, make
2572 sure REG matches. Otherwise some_was_live will be clear
2573 when it shouldn't have been, and we'll create incorrect
2574 REG_UNUSED notes. */
2575 reg
= gen_rtx_REG (outer_mode
, regno_first
);
2579 /* If the number of words in the subreg is less than the number
2580 of words in the full register, we have a well-defined partial
2581 set. Otherwise the high bits are undefined.
2583 This is only really applicable to pseudos, since we just took
2584 care of multi-word hard registers. */
2585 if (((GET_MODE_SIZE (outer_mode
)
2586 + UNITS_PER_WORD
- 1) / UNITS_PER_WORD
)
2587 < ((GET_MODE_SIZE (inner_mode
)
2588 + UNITS_PER_WORD
- 1) / UNITS_PER_WORD
))
2589 not_dead
= (unsigned long) REGNO_REG_SET_P (pbi
->reg_live
,
2592 reg
= SUBREG_REG (reg
);
2596 reg
= SUBREG_REG (reg
);
2603 /* If this set is a MEM, then it kills any aliased writes.
2604 If this set is a REG, then it kills any MEMs which use the reg. */
2605 if (optimize
&& (flags
& PROP_SCAN_DEAD_STORES
))
2608 invalidate_mems_from_set (pbi
, reg
);
2610 /* If the memory reference had embedded side effects (autoincrement
2611 address modes. Then we may need to kill some entries on the
2613 if (insn
&& MEM_P (reg
))
2614 for_each_rtx (&PATTERN (insn
), invalidate_mems_from_autoinc
, pbi
);
2616 if (MEM_P (reg
) && ! side_effects_p (reg
)
2617 /* ??? With more effort we could track conditional memory life. */
2619 add_to_mem_set_list (pbi
, canon_rtx (reg
));
2623 && ! (regno_first
== FRAME_POINTER_REGNUM
2624 && (! reload_completed
|| frame_pointer_needed
))
2625 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
2626 && ! (regno_first
== HARD_FRAME_POINTER_REGNUM
2627 && (! reload_completed
|| frame_pointer_needed
))
2629 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
2630 && ! (regno_first
== ARG_POINTER_REGNUM
&& fixed_regs
[regno_first
])
2634 int some_was_live
= 0, some_was_dead
= 0;
2636 for (i
= regno_first
; i
<= regno_last
; ++i
)
2638 int needed_regno
= REGNO_REG_SET_P (pbi
->reg_live
, i
);
2641 /* Order of the set operation matters here since both
2642 sets may be the same. */
2643 CLEAR_REGNO_REG_SET (pbi
->cond_local_set
, i
);
2644 if (cond
!= NULL_RTX
2645 && ! REGNO_REG_SET_P (pbi
->local_set
, i
))
2646 SET_REGNO_REG_SET (pbi
->cond_local_set
, i
);
2648 SET_REGNO_REG_SET (pbi
->local_set
, i
);
2650 if (code
!= CLOBBER
)
2651 SET_REGNO_REG_SET (pbi
->new_set
, i
);
2653 some_was_live
|= needed_regno
;
2654 some_was_dead
|= ! needed_regno
;
2657 #ifdef HAVE_conditional_execution
2658 /* Consider conditional death in deciding that the register needs
2660 if (some_was_live
&& ! not_dead
2661 /* The stack pointer is never dead. Well, not strictly true,
2662 but it's very difficult to tell from here. Hopefully
2663 combine_stack_adjustments will fix up the most egregious
2665 && regno_first
!= STACK_POINTER_REGNUM
)
2667 for (i
= regno_first
; i
<= regno_last
; ++i
)
2668 if (! mark_regno_cond_dead (pbi
, i
, cond
))
2669 not_dead
|= ((unsigned long) 1) << (i
- regno_first
);
2673 /* Additional data to record if this is the final pass. */
2674 if (flags
& (PROP_LOG_LINKS
| PROP_REG_INFO
2675 | PROP_DEATH_NOTES
| PROP_AUTOINC
))
2678 int blocknum
= pbi
->bb
->index
;
2681 if (flags
& (PROP_LOG_LINKS
| PROP_AUTOINC
))
2683 y
= pbi
->reg_next_use
[regno_first
];
2685 /* The next use is no longer next, since a store intervenes. */
2686 for (i
= regno_first
; i
<= regno_last
; ++i
)
2687 pbi
->reg_next_use
[i
] = 0;
2690 if (flags
& PROP_REG_INFO
)
2692 for (i
= regno_first
; i
<= regno_last
; ++i
)
2694 /* Count (weighted) references, stores, etc. This counts a
2695 register twice if it is modified, but that is correct. */
2696 REG_N_SETS (i
) += 1;
2697 REG_N_REFS (i
) += 1;
2698 REG_FREQ (i
) += REG_FREQ_FROM_BB (pbi
->bb
);
2700 /* The insns where a reg is live are normally counted
2701 elsewhere, but we want the count to include the insn
2702 where the reg is set, and the normal counting mechanism
2703 would not count it. */
2704 REG_LIVE_LENGTH (i
) += 1;
2707 /* If this is a hard reg, record this function uses the reg. */
2708 if (regno_first
< FIRST_PSEUDO_REGISTER
)
2710 for (i
= regno_first
; i
<= regno_last
; i
++)
2711 regs_ever_live
[i
] = 1;
2712 if (flags
& PROP_ASM_SCAN
)
2713 for (i
= regno_first
; i
<= regno_last
; i
++)
2714 regs_asm_clobbered
[i
] = 1;
2718 /* Keep track of which basic blocks each reg appears in. */
2719 if (REG_BASIC_BLOCK (regno_first
) == REG_BLOCK_UNKNOWN
)
2720 REG_BASIC_BLOCK (regno_first
) = blocknum
;
2721 else if (REG_BASIC_BLOCK (regno_first
) != blocknum
)
2722 REG_BASIC_BLOCK (regno_first
) = REG_BLOCK_GLOBAL
;
2726 if (! some_was_dead
)
2728 if (flags
& PROP_LOG_LINKS
)
2730 /* Make a logical link from the next following insn
2731 that uses this register, back to this insn.
2732 The following insns have already been processed.
2734 We don't build a LOG_LINK for hard registers containing
2735 in ASM_OPERANDs. If these registers get replaced,
2736 we might wind up changing the semantics of the insn,
2737 even if reload can make what appear to be valid
2740 We don't build a LOG_LINK for global registers to
2741 or from a function call. We don't want to let
2742 combine think that it knows what is going on with
2743 global registers. */
2744 if (y
&& (BLOCK_NUM (y
) == blocknum
)
2745 && (regno_first
>= FIRST_PSEUDO_REGISTER
2746 || (asm_noperands (PATTERN (y
)) < 0
2747 && ! ((CALL_P (insn
)
2749 && global_regs
[regno_first
]))))
2750 LOG_LINKS (y
) = alloc_INSN_LIST (insn
, LOG_LINKS (y
));
2755 else if (! some_was_live
)
2757 if (flags
& PROP_REG_INFO
)
2758 REG_N_DEATHS (regno_first
) += 1;
2760 if (flags
& PROP_DEATH_NOTES
)
2762 /* Note that dead stores have already been deleted
2763 when possible. If we get here, we have found a
2764 dead store that cannot be eliminated (because the
2765 same insn does something useful). Indicate this
2766 by marking the reg being set as dying here. */
2768 = alloc_EXPR_LIST (REG_UNUSED
, reg
, REG_NOTES (insn
));
2773 if (flags
& PROP_DEATH_NOTES
)
2775 /* This is a case where we have a multi-word hard register
2776 and some, but not all, of the words of the register are
2777 needed in subsequent insns. Write REG_UNUSED notes
2778 for those parts that were not needed. This case should
2781 for (i
= regno_first
; i
<= regno_last
; ++i
)
2782 if (! REGNO_REG_SET_P (pbi
->reg_live
, i
))
2784 = alloc_EXPR_LIST (REG_UNUSED
,
2791 /* Mark the register as being dead. */
2793 /* The stack pointer is never dead. Well, not strictly true,
2794 but it's very difficult to tell from here. Hopefully
2795 combine_stack_adjustments will fix up the most egregious
2797 && regno_first
!= STACK_POINTER_REGNUM
)
2799 for (i
= regno_first
; i
<= regno_last
; ++i
)
2800 if (!(not_dead
& (((unsigned long) 1) << (i
- regno_first
))))
2802 if ((pbi
->flags
& PROP_REG_INFO
)
2803 && REGNO_REG_SET_P (pbi
->reg_live
, i
))
2805 REG_LIVE_LENGTH (i
) += pbi
->insn_num
- reg_deaths
[i
];
2808 CLEAR_REGNO_REG_SET (pbi
->reg_live
, i
);
2812 else if (REG_P (reg
))
2814 if (flags
& (PROP_LOG_LINKS
| PROP_AUTOINC
))
2815 pbi
->reg_next_use
[regno_first
] = 0;
2817 if ((flags
& PROP_REG_INFO
) != 0
2818 && (flags
& PROP_ASM_SCAN
) != 0
2819 && regno_first
< FIRST_PSEUDO_REGISTER
)
2821 for (i
= regno_first
; i
<= regno_last
; i
++)
2822 regs_asm_clobbered
[i
] = 1;
2826 /* If this is the last pass and this is a SCRATCH, show it will be dying
2827 here and count it. */
2828 else if (GET_CODE (reg
) == SCRATCH
)
2830 if (flags
& PROP_DEATH_NOTES
)
2832 = alloc_EXPR_LIST (REG_UNUSED
, reg
, REG_NOTES (insn
));
2836 #ifdef HAVE_conditional_execution
2837 /* Mark REGNO conditionally dead.
2838 Return true if the register is now unconditionally dead. */
2841 mark_regno_cond_dead (struct propagate_block_info
*pbi
, int regno
, rtx cond
)
2843 /* If this is a store to a predicate register, the value of the
2844 predicate is changing, we don't know that the predicate as seen
2845 before is the same as that seen after. Flush all dependent
2846 conditions from reg_cond_dead. This will make all such
2847 conditionally live registers unconditionally live. */
2848 if (REGNO_REG_SET_P (pbi
->reg_cond_reg
, regno
))
2849 flush_reg_cond_reg (pbi
, regno
);
2851 /* If this is an unconditional store, remove any conditional
2852 life that may have existed. */
2853 if (cond
== NULL_RTX
)
2854 splay_tree_remove (pbi
->reg_cond_dead
, regno
);
2857 splay_tree_node node
;
2858 struct reg_cond_life_info
*rcli
;
2861 /* Otherwise this is a conditional set. Record that fact.
2862 It may have been conditionally used, or there may be a
2863 subsequent set with a complimentary condition. */
2865 node
= splay_tree_lookup (pbi
->reg_cond_dead
, regno
);
2868 /* The register was unconditionally live previously.
2869 Record the current condition as the condition under
2870 which it is dead. */
2871 rcli
= xmalloc (sizeof (*rcli
));
2872 rcli
->condition
= cond
;
2873 rcli
->stores
= cond
;
2874 rcli
->orig_condition
= const0_rtx
;
2875 splay_tree_insert (pbi
->reg_cond_dead
, regno
,
2876 (splay_tree_value
) rcli
);
2878 SET_REGNO_REG_SET (pbi
->reg_cond_reg
, REGNO (XEXP (cond
, 0)));
2880 /* Not unconditionally dead. */
2885 /* The register was conditionally live previously.
2886 Add the new condition to the old. */
2887 rcli
= (struct reg_cond_life_info
*) node
->value
;
2888 ncond
= rcli
->condition
;
2889 ncond
= ior_reg_cond (ncond
, cond
, 1);
2890 if (rcli
->stores
== const0_rtx
)
2891 rcli
->stores
= cond
;
2892 else if (rcli
->stores
!= const1_rtx
)
2893 rcli
->stores
= ior_reg_cond (rcli
->stores
, cond
, 1);
2895 /* If the register is now unconditionally dead, remove the entry
2896 in the splay_tree. A register is unconditionally dead if the
2897 dead condition ncond is true. A register is also unconditionally
2898 dead if the sum of all conditional stores is an unconditional
2899 store (stores is true), and the dead condition is identically the
2900 same as the original dead condition initialized at the end of
2901 the block. This is a pointer compare, not an rtx_equal_p
2903 if (ncond
== const1_rtx
2904 || (ncond
== rcli
->orig_condition
&& rcli
->stores
== const1_rtx
))
2905 splay_tree_remove (pbi
->reg_cond_dead
, regno
);
2908 rcli
->condition
= ncond
;
2910 SET_REGNO_REG_SET (pbi
->reg_cond_reg
, REGNO (XEXP (cond
, 0)));
2912 /* Not unconditionally dead. */
2921 /* Called from splay_tree_delete for pbi->reg_cond_life. */
2924 free_reg_cond_life_info (splay_tree_value value
)
2926 struct reg_cond_life_info
*rcli
= (struct reg_cond_life_info
*) value
;
2930 /* Helper function for flush_reg_cond_reg. */
2933 flush_reg_cond_reg_1 (splay_tree_node node
, void *data
)
2935 struct reg_cond_life_info
*rcli
;
2936 int *xdata
= (int *) data
;
2937 unsigned int regno
= xdata
[0];
2939 /* Don't need to search if last flushed value was farther on in
2940 the in-order traversal. */
2941 if (xdata
[1] >= (int) node
->key
)
2944 /* Splice out portions of the expression that refer to regno. */
2945 rcli
= (struct reg_cond_life_info
*) node
->value
;
2946 rcli
->condition
= elim_reg_cond (rcli
->condition
, regno
);
2947 if (rcli
->stores
!= const0_rtx
&& rcli
->stores
!= const1_rtx
)
2948 rcli
->stores
= elim_reg_cond (rcli
->stores
, regno
);
2950 /* If the entire condition is now false, signal the node to be removed. */
2951 if (rcli
->condition
== const0_rtx
)
2953 xdata
[1] = node
->key
;
2957 gcc_assert (rcli
->condition
!= const1_rtx
);
2962 /* Flush all (sub) expressions referring to REGNO from REG_COND_LIVE. */
2965 flush_reg_cond_reg (struct propagate_block_info
*pbi
, int regno
)
2971 while (splay_tree_foreach (pbi
->reg_cond_dead
,
2972 flush_reg_cond_reg_1
, pair
) == -1)
2973 splay_tree_remove (pbi
->reg_cond_dead
, pair
[1]);
2975 CLEAR_REGNO_REG_SET (pbi
->reg_cond_reg
, regno
);
2978 /* Logical arithmetic on predicate conditions. IOR, NOT and AND.
2979 For ior/and, the ADD flag determines whether we want to add the new
2980 condition X to the old one unconditionally. If it is zero, we will
2981 only return a new expression if X allows us to simplify part of
2982 OLD, otherwise we return NULL to the caller.
2983 If ADD is nonzero, we will return a new condition in all cases. The
2984 toplevel caller of one of these functions should always pass 1 for
2988 ior_reg_cond (rtx old
, rtx x
, int add
)
2992 if (COMPARISON_P (old
))
2994 if (COMPARISON_P (x
)
2995 && REVERSE_CONDEXEC_PREDICATES_P (x
, old
)
2996 && REGNO (XEXP (x
, 0)) == REGNO (XEXP (old
, 0)))
2998 if (GET_CODE (x
) == GET_CODE (old
)
2999 && REGNO (XEXP (x
, 0)) == REGNO (XEXP (old
, 0)))
3003 return gen_rtx_IOR (0, old
, x
);
3006 switch (GET_CODE (old
))
3009 op0
= ior_reg_cond (XEXP (old
, 0), x
, 0);
3010 op1
= ior_reg_cond (XEXP (old
, 1), x
, 0);
3011 if (op0
!= NULL
|| op1
!= NULL
)
3013 if (op0
== const0_rtx
)
3014 return op1
? op1
: gen_rtx_IOR (0, XEXP (old
, 1), x
);
3015 if (op1
== const0_rtx
)
3016 return op0
? op0
: gen_rtx_IOR (0, XEXP (old
, 0), x
);
3017 if (op0
== const1_rtx
|| op1
== const1_rtx
)
3020 op0
= gen_rtx_IOR (0, XEXP (old
, 0), x
);
3021 else if (rtx_equal_p (x
, op0
))
3022 /* (x | A) | x ~ (x | A). */
3025 op1
= gen_rtx_IOR (0, XEXP (old
, 1), x
);
3026 else if (rtx_equal_p (x
, op1
))
3027 /* (A | x) | x ~ (A | x). */
3029 return gen_rtx_IOR (0, op0
, op1
);
3033 return gen_rtx_IOR (0, old
, x
);
3036 op0
= ior_reg_cond (XEXP (old
, 0), x
, 0);
3037 op1
= ior_reg_cond (XEXP (old
, 1), x
, 0);
3038 if (op0
!= NULL
|| op1
!= NULL
)
3040 if (op0
== const1_rtx
)
3041 return op1
? op1
: gen_rtx_IOR (0, XEXP (old
, 1), x
);
3042 if (op1
== const1_rtx
)
3043 return op0
? op0
: gen_rtx_IOR (0, XEXP (old
, 0), x
);
3044 if (op0
== const0_rtx
|| op1
== const0_rtx
)
3047 op0
= gen_rtx_IOR (0, XEXP (old
, 0), x
);
3048 else if (rtx_equal_p (x
, op0
))
3049 /* (x & A) | x ~ x. */
3052 op1
= gen_rtx_IOR (0, XEXP (old
, 1), x
);
3053 else if (rtx_equal_p (x
, op1
))
3054 /* (A & x) | x ~ x. */
3056 return gen_rtx_AND (0, op0
, op1
);
3060 return gen_rtx_IOR (0, old
, x
);
3063 op0
= and_reg_cond (XEXP (old
, 0), not_reg_cond (x
), 0);
3065 return not_reg_cond (op0
);
3068 return gen_rtx_IOR (0, old
, x
);
3076 not_reg_cond (rtx x
)
3078 if (x
== const0_rtx
)
3080 else if (x
== const1_rtx
)
3082 if (GET_CODE (x
) == NOT
)
3084 if (COMPARISON_P (x
)
3085 && REG_P (XEXP (x
, 0)))
3087 gcc_assert (XEXP (x
, 1) == const0_rtx
);
3089 return gen_rtx_fmt_ee (reversed_comparison_code (x
, NULL
),
3090 VOIDmode
, XEXP (x
, 0), const0_rtx
);
3092 return gen_rtx_NOT (0, x
);
3096 and_reg_cond (rtx old
, rtx x
, int add
)
3100 if (COMPARISON_P (old
))
3102 if (COMPARISON_P (x
)
3103 && GET_CODE (x
) == reversed_comparison_code (old
, NULL
)
3104 && REGNO (XEXP (x
, 0)) == REGNO (XEXP (old
, 0)))
3106 if (GET_CODE (x
) == GET_CODE (old
)
3107 && REGNO (XEXP (x
, 0)) == REGNO (XEXP (old
, 0)))
3111 return gen_rtx_AND (0, old
, x
);
3114 switch (GET_CODE (old
))
3117 op0
= and_reg_cond (XEXP (old
, 0), x
, 0);
3118 op1
= and_reg_cond (XEXP (old
, 1), x
, 0);
3119 if (op0
!= NULL
|| op1
!= NULL
)
3121 if (op0
== const0_rtx
)
3122 return op1
? op1
: gen_rtx_AND (0, XEXP (old
, 1), x
);
3123 if (op1
== const0_rtx
)
3124 return op0
? op0
: gen_rtx_AND (0, XEXP (old
, 0), x
);
3125 if (op0
== const1_rtx
|| op1
== const1_rtx
)
3128 op0
= gen_rtx_AND (0, XEXP (old
, 0), x
);
3129 else if (rtx_equal_p (x
, op0
))
3130 /* (x | A) & x ~ x. */
3133 op1
= gen_rtx_AND (0, XEXP (old
, 1), x
);
3134 else if (rtx_equal_p (x
, op1
))
3135 /* (A | x) & x ~ x. */
3137 return gen_rtx_IOR (0, op0
, op1
);
3141 return gen_rtx_AND (0, old
, x
);
3144 op0
= and_reg_cond (XEXP (old
, 0), x
, 0);
3145 op1
= and_reg_cond (XEXP (old
, 1), x
, 0);
3146 if (op0
!= NULL
|| op1
!= NULL
)
3148 if (op0
== const1_rtx
)
3149 return op1
? op1
: gen_rtx_AND (0, XEXP (old
, 1), x
);
3150 if (op1
== const1_rtx
)
3151 return op0
? op0
: gen_rtx_AND (0, XEXP (old
, 0), x
);
3152 if (op0
== const0_rtx
|| op1
== const0_rtx
)
3155 op0
= gen_rtx_AND (0, XEXP (old
, 0), x
);
3156 else if (rtx_equal_p (x
, op0
))
3157 /* (x & A) & x ~ (x & A). */
3160 op1
= gen_rtx_AND (0, XEXP (old
, 1), x
);
3161 else if (rtx_equal_p (x
, op1
))
3162 /* (A & x) & x ~ (A & x). */
3164 return gen_rtx_AND (0, op0
, op1
);
3168 return gen_rtx_AND (0, old
, x
);
3171 op0
= ior_reg_cond (XEXP (old
, 0), not_reg_cond (x
), 0);
3173 return not_reg_cond (op0
);
3176 return gen_rtx_AND (0, old
, x
);
3183 /* Given a condition X, remove references to reg REGNO and return the
3184 new condition. The removal will be done so that all conditions
3185 involving REGNO are considered to evaluate to false. This function
3186 is used when the value of REGNO changes. */
3189 elim_reg_cond (rtx x
, unsigned int regno
)
3193 if (COMPARISON_P (x
))
3195 if (REGNO (XEXP (x
, 0)) == regno
)
3200 switch (GET_CODE (x
))
3203 op0
= elim_reg_cond (XEXP (x
, 0), regno
);
3204 op1
= elim_reg_cond (XEXP (x
, 1), regno
);
3205 if (op0
== const0_rtx
|| op1
== const0_rtx
)
3207 if (op0
== const1_rtx
)
3209 if (op1
== const1_rtx
)
3211 if (op0
== XEXP (x
, 0) && op1
== XEXP (x
, 1))
3213 return gen_rtx_AND (0, op0
, op1
);
3216 op0
= elim_reg_cond (XEXP (x
, 0), regno
);
3217 op1
= elim_reg_cond (XEXP (x
, 1), regno
);
3218 if (op0
== const1_rtx
|| op1
== const1_rtx
)
3220 if (op0
== const0_rtx
)
3222 if (op1
== const0_rtx
)
3224 if (op0
== XEXP (x
, 0) && op1
== XEXP (x
, 1))
3226 return gen_rtx_IOR (0, op0
, op1
);
3229 op0
= elim_reg_cond (XEXP (x
, 0), regno
);
3230 if (op0
== const0_rtx
)
3232 if (op0
== const1_rtx
)
3234 if (op0
!= XEXP (x
, 0))
3235 return not_reg_cond (op0
);
3242 #endif /* HAVE_conditional_execution */
3246 /* Try to substitute the auto-inc expression INC as the address inside
3247 MEM which occurs in INSN. Currently, the address of MEM is an expression
3248 involving INCR_REG, and INCR is the next use of INCR_REG; it is an insn
3249 that has a single set whose source is a PLUS of INCR_REG and something
3253 attempt_auto_inc (struct propagate_block_info
*pbi
, rtx inc
, rtx insn
,
3254 rtx mem
, rtx incr
, rtx incr_reg
)
3256 int regno
= REGNO (incr_reg
);
3257 rtx set
= single_set (incr
);
3258 rtx q
= SET_DEST (set
);
3259 rtx y
= SET_SRC (set
);
3260 int opnum
= XEXP (y
, 0) == incr_reg
? 0 : 1;
3263 /* Make sure this reg appears only once in this insn. */
3264 if (count_occurrences (PATTERN (insn
), incr_reg
, 1) != 1)
3267 if (dead_or_set_p (incr
, incr_reg
)
3268 /* Mustn't autoinc an eliminable register. */
3269 && (regno
>= FIRST_PSEUDO_REGISTER
3270 || ! TEST_HARD_REG_BIT (elim_reg_set
, regno
)))
3272 /* This is the simple case. Try to make the auto-inc. If
3273 we can't, we are done. Otherwise, we will do any
3274 needed updates below. */
3275 if (! validate_change (insn
, &XEXP (mem
, 0), inc
, 0))
3279 /* PREV_INSN used here to check the semi-open interval
3281 && ! reg_used_between_p (q
, PREV_INSN (insn
), incr
)
3282 /* We must also check for sets of q as q may be
3283 a call clobbered hard register and there may
3284 be a call between PREV_INSN (insn) and incr. */
3285 && ! reg_set_between_p (q
, PREV_INSN (insn
), incr
))
3287 /* We have *p followed sometime later by q = p+size.
3288 Both p and q must be live afterward,
3289 and q is not used between INSN and its assignment.
3290 Change it to q = p, ...*q..., q = q+size.
3291 Then fall into the usual case. */
3295 emit_move_insn (q
, incr_reg
);
3296 insns
= get_insns ();
3299 /* If we can't make the auto-inc, or can't make the
3300 replacement into Y, exit. There's no point in making
3301 the change below if we can't do the auto-inc and doing
3302 so is not correct in the pre-inc case. */
3305 validate_change (insn
, &XEXP (mem
, 0), inc
, 1);
3306 validate_change (incr
, &XEXP (y
, opnum
), q
, 1);
3307 if (! apply_change_group ())
3310 /* We now know we'll be doing this change, so emit the
3311 new insn(s) and do the updates. */
3312 emit_insn_before (insns
, insn
);
3314 if (BB_HEAD (pbi
->bb
) == insn
)
3315 BB_HEAD (pbi
->bb
) = insns
;
3317 /* INCR will become a NOTE and INSN won't contain a
3318 use of INCR_REG. If a use of INCR_REG was just placed in
3319 the insn before INSN, make that the next use.
3320 Otherwise, invalidate it. */
3321 if (NONJUMP_INSN_P (PREV_INSN (insn
))
3322 && GET_CODE (PATTERN (PREV_INSN (insn
))) == SET
3323 && SET_SRC (PATTERN (PREV_INSN (insn
))) == incr_reg
)
3324 pbi
->reg_next_use
[regno
] = PREV_INSN (insn
);
3326 pbi
->reg_next_use
[regno
] = 0;
3331 if ((pbi
->flags
& PROP_REG_INFO
)
3332 && !REGNO_REG_SET_P (pbi
->reg_live
, regno
))
3333 reg_deaths
[regno
] = pbi
->insn_num
;
3335 /* REGNO is now used in INCR which is below INSN, but
3336 it previously wasn't live here. If we don't mark
3337 it as live, we'll put a REG_DEAD note for it
3338 on this insn, which is incorrect. */
3339 SET_REGNO_REG_SET (pbi
->reg_live
, regno
);
3341 /* If there are any calls between INSN and INCR, show
3342 that REGNO now crosses them. */
3343 for (temp
= insn
; temp
!= incr
; temp
= NEXT_INSN (temp
))
3345 REG_N_CALLS_CROSSED (regno
)++;
3347 /* Invalidate alias info for Q since we just changed its value. */
3348 clear_reg_alias_info (q
);
3353 /* If we haven't returned, it means we were able to make the
3354 auto-inc, so update the status. First, record that this insn
3355 has an implicit side effect. */
3357 REG_NOTES (insn
) = alloc_EXPR_LIST (REG_INC
, incr_reg
, REG_NOTES (insn
));
3359 /* Modify the old increment-insn to simply copy
3360 the already-incremented value of our register. */
3361 changed
= validate_change (incr
, &SET_SRC (set
), incr_reg
, 0);
3362 gcc_assert (changed
);
3364 /* If that makes it a no-op (copying the register into itself) delete
3365 it so it won't appear to be a "use" and a "set" of this
3367 if (REGNO (SET_DEST (set
)) == REGNO (incr_reg
))
3369 /* If the original source was dead, it's dead now. */
3372 while ((note
= find_reg_note (incr
, REG_DEAD
, NULL_RTX
)) != NULL_RTX
)
3374 remove_note (incr
, note
);
3375 if (XEXP (note
, 0) != incr_reg
)
3377 unsigned int regno
= REGNO (XEXP (note
, 0));
3379 if ((pbi
->flags
& PROP_REG_INFO
)
3380 && REGNO_REG_SET_P (pbi
->reg_live
, regno
))
3382 REG_LIVE_LENGTH (regno
) += pbi
->insn_num
- reg_deaths
[regno
];
3383 reg_deaths
[regno
] = 0;
3385 CLEAR_REGNO_REG_SET (pbi
->reg_live
, REGNO (XEXP (note
, 0)));
3389 SET_INSN_DELETED (incr
);
3392 if (regno
>= FIRST_PSEUDO_REGISTER
)
3394 /* Count an extra reference to the reg. When a reg is
3395 incremented, spilling it is worse, so we want to make
3396 that less likely. */
3397 REG_FREQ (regno
) += REG_FREQ_FROM_BB (pbi
->bb
);
3399 /* Count the increment as a setting of the register,
3400 even though it isn't a SET in rtl. */
3401 REG_N_SETS (regno
)++;
3405 /* X is a MEM found in INSN. See if we can convert it into an auto-increment
3409 find_auto_inc (struct propagate_block_info
*pbi
, rtx x
, rtx insn
)
3411 rtx addr
= XEXP (x
, 0);
3412 HOST_WIDE_INT offset
= 0;
3413 rtx set
, y
, incr
, inc_val
;
3415 int size
= GET_MODE_SIZE (GET_MODE (x
));
3420 /* Here we detect use of an index register which might be good for
3421 postincrement, postdecrement, preincrement, or predecrement. */
3423 if (GET_CODE (addr
) == PLUS
&& GET_CODE (XEXP (addr
, 1)) == CONST_INT
)
3424 offset
= INTVAL (XEXP (addr
, 1)), addr
= XEXP (addr
, 0);
3429 regno
= REGNO (addr
);
3431 /* Is the next use an increment that might make auto-increment? */
3432 incr
= pbi
->reg_next_use
[regno
];
3433 if (incr
== 0 || BLOCK_NUM (incr
) != BLOCK_NUM (insn
))
3435 set
= single_set (incr
);
3436 if (set
== 0 || GET_CODE (set
) != SET
)
3440 if (GET_CODE (y
) != PLUS
)
3443 if (REG_P (XEXP (y
, 0)) && REGNO (XEXP (y
, 0)) == REGNO (addr
))
3444 inc_val
= XEXP (y
, 1);
3445 else if (REG_P (XEXP (y
, 1)) && REGNO (XEXP (y
, 1)) == REGNO (addr
))
3446 inc_val
= XEXP (y
, 0);
3450 if (GET_CODE (inc_val
) == CONST_INT
)
3452 if (HAVE_POST_INCREMENT
3453 && (INTVAL (inc_val
) == size
&& offset
== 0))
3454 attempt_auto_inc (pbi
, gen_rtx_POST_INC (Pmode
, addr
), insn
, x
,
3456 else if (HAVE_POST_DECREMENT
3457 && (INTVAL (inc_val
) == -size
&& offset
== 0))
3458 attempt_auto_inc (pbi
, gen_rtx_POST_DEC (Pmode
, addr
), insn
, x
,
3460 else if (HAVE_PRE_INCREMENT
3461 && (INTVAL (inc_val
) == size
&& offset
== size
))
3462 attempt_auto_inc (pbi
, gen_rtx_PRE_INC (Pmode
, addr
), insn
, x
,
3464 else if (HAVE_PRE_DECREMENT
3465 && (INTVAL (inc_val
) == -size
&& offset
== -size
))
3466 attempt_auto_inc (pbi
, gen_rtx_PRE_DEC (Pmode
, addr
), insn
, x
,
3468 else if (HAVE_POST_MODIFY_DISP
&& offset
== 0)
3469 attempt_auto_inc (pbi
, gen_rtx_POST_MODIFY (Pmode
, addr
,
3470 gen_rtx_PLUS (Pmode
,
3473 insn
, x
, incr
, addr
);
3474 else if (HAVE_PRE_MODIFY_DISP
&& offset
== INTVAL (inc_val
))
3475 attempt_auto_inc (pbi
, gen_rtx_PRE_MODIFY (Pmode
, addr
,
3476 gen_rtx_PLUS (Pmode
,
3479 insn
, x
, incr
, addr
);
3481 else if (REG_P (inc_val
)
3482 && ! reg_set_between_p (inc_val
, PREV_INSN (insn
),
3486 if (HAVE_POST_MODIFY_REG
&& offset
== 0)
3487 attempt_auto_inc (pbi
, gen_rtx_POST_MODIFY (Pmode
, addr
,
3488 gen_rtx_PLUS (Pmode
,
3491 insn
, x
, incr
, addr
);
3495 #endif /* AUTO_INC_DEC */
3498 mark_used_reg (struct propagate_block_info
*pbi
, rtx reg
,
3499 rtx cond ATTRIBUTE_UNUSED
, rtx insn
)
3501 unsigned int regno_first
, regno_last
, i
;
3502 int some_was_live
, some_was_dead
, some_not_set
;
3504 regno_last
= regno_first
= REGNO (reg
);
3505 if (regno_first
< FIRST_PSEUDO_REGISTER
)
3506 regno_last
+= hard_regno_nregs
[regno_first
][GET_MODE (reg
)] - 1;
3508 /* Find out if any of this register is live after this instruction. */
3509 some_was_live
= some_was_dead
= 0;
3510 for (i
= regno_first
; i
<= regno_last
; ++i
)
3512 int needed_regno
= REGNO_REG_SET_P (pbi
->reg_live
, i
);
3513 some_was_live
|= needed_regno
;
3514 some_was_dead
|= ! needed_regno
;
3517 /* Find out if any of the register was set this insn. */
3519 for (i
= regno_first
; i
<= regno_last
; ++i
)
3520 some_not_set
|= ! REGNO_REG_SET_P (pbi
->new_set
, i
);
3522 if (pbi
->flags
& (PROP_LOG_LINKS
| PROP_AUTOINC
))
3524 /* Record where each reg is used, so when the reg is set we know
3525 the next insn that uses it. */
3526 pbi
->reg_next_use
[regno_first
] = insn
;
3529 if (pbi
->flags
& PROP_REG_INFO
)
3531 if (regno_first
< FIRST_PSEUDO_REGISTER
)
3533 /* If this is a register we are going to try to eliminate,
3534 don't mark it live here. If we are successful in
3535 eliminating it, it need not be live unless it is used for
3536 pseudos, in which case it will have been set live when it
3537 was allocated to the pseudos. If the register will not
3538 be eliminated, reload will set it live at that point.
3540 Otherwise, record that this function uses this register. */
3541 /* ??? The PPC backend tries to "eliminate" on the pic
3542 register to itself. This should be fixed. In the mean
3543 time, hack around it. */
3545 if (! (TEST_HARD_REG_BIT (elim_reg_set
, regno_first
)
3546 && (regno_first
== FRAME_POINTER_REGNUM
3547 || regno_first
== ARG_POINTER_REGNUM
)))
3548 for (i
= regno_first
; i
<= regno_last
; ++i
)
3549 regs_ever_live
[i
] = 1;
3553 /* Keep track of which basic block each reg appears in. */
3555 int blocknum
= pbi
->bb
->index
;
3556 if (REG_BASIC_BLOCK (regno_first
) == REG_BLOCK_UNKNOWN
)
3557 REG_BASIC_BLOCK (regno_first
) = blocknum
;
3558 else if (REG_BASIC_BLOCK (regno_first
) != blocknum
)
3559 REG_BASIC_BLOCK (regno_first
) = REG_BLOCK_GLOBAL
;
3561 /* Count (weighted) number of uses of each reg. */
3562 REG_FREQ (regno_first
) += REG_FREQ_FROM_BB (pbi
->bb
);
3563 REG_N_REFS (regno_first
)++;
3565 for (i
= regno_first
; i
<= regno_last
; ++i
)
3566 if (! REGNO_REG_SET_P (pbi
->reg_live
, i
))
3568 gcc_assert (!reg_deaths
[i
]);
3569 reg_deaths
[i
] = pbi
->insn_num
;
3573 /* Record and count the insns in which a reg dies. If it is used in
3574 this insn and was dead below the insn then it dies in this insn.
3575 If it was set in this insn, we do not make a REG_DEAD note;
3576 likewise if we already made such a note. */
3577 if ((pbi
->flags
& (PROP_DEATH_NOTES
| PROP_REG_INFO
))
3581 /* Check for the case where the register dying partially
3582 overlaps the register set by this insn. */
3583 if (regno_first
!= regno_last
)
3584 for (i
= regno_first
; i
<= regno_last
; ++i
)
3585 some_was_live
|= REGNO_REG_SET_P (pbi
->new_set
, i
);
3587 /* If none of the words in X is needed, make a REG_DEAD note.
3588 Otherwise, we must make partial REG_DEAD notes. */
3589 if (! some_was_live
)
3591 if ((pbi
->flags
& PROP_DEATH_NOTES
)
3592 && ! find_regno_note (insn
, REG_DEAD
, regno_first
))
3594 = alloc_EXPR_LIST (REG_DEAD
, reg
, REG_NOTES (insn
));
3596 if (pbi
->flags
& PROP_REG_INFO
)
3597 REG_N_DEATHS (regno_first
)++;
3601 /* Don't make a REG_DEAD note for a part of a register
3602 that is set in the insn. */
3603 for (i
= regno_first
; i
<= regno_last
; ++i
)
3604 if (! REGNO_REG_SET_P (pbi
->reg_live
, i
)
3605 && ! dead_or_set_regno_p (insn
, i
))
3607 = alloc_EXPR_LIST (REG_DEAD
,
3613 /* Mark the register as being live. */
3614 for (i
= regno_first
; i
<= regno_last
; ++i
)
3616 #ifdef HAVE_conditional_execution
3617 int this_was_live
= REGNO_REG_SET_P (pbi
->reg_live
, i
);
3620 SET_REGNO_REG_SET (pbi
->reg_live
, i
);
3622 #ifdef HAVE_conditional_execution
3623 /* If this is a conditional use, record that fact. If it is later
3624 conditionally set, we'll know to kill the register. */
3625 if (cond
!= NULL_RTX
)
3627 splay_tree_node node
;
3628 struct reg_cond_life_info
*rcli
;
3633 node
= splay_tree_lookup (pbi
->reg_cond_dead
, i
);
3636 /* The register was unconditionally live previously.
3637 No need to do anything. */
3641 /* The register was conditionally live previously.
3642 Subtract the new life cond from the old death cond. */
3643 rcli
= (struct reg_cond_life_info
*) node
->value
;
3644 ncond
= rcli
->condition
;
3645 ncond
= and_reg_cond (ncond
, not_reg_cond (cond
), 1);
3647 /* If the register is now unconditionally live,
3648 remove the entry in the splay_tree. */
3649 if (ncond
== const0_rtx
)
3650 splay_tree_remove (pbi
->reg_cond_dead
, i
);
3653 rcli
->condition
= ncond
;
3654 SET_REGNO_REG_SET (pbi
->reg_cond_reg
,
3655 REGNO (XEXP (cond
, 0)));
3661 /* The register was not previously live at all. Record
3662 the condition under which it is still dead. */
3663 rcli
= xmalloc (sizeof (*rcli
));
3664 rcli
->condition
= not_reg_cond (cond
);
3665 rcli
->stores
= const0_rtx
;
3666 rcli
->orig_condition
= const0_rtx
;
3667 splay_tree_insert (pbi
->reg_cond_dead
, i
,
3668 (splay_tree_value
) rcli
);
3670 SET_REGNO_REG_SET (pbi
->reg_cond_reg
, REGNO (XEXP (cond
, 0)));
3673 else if (this_was_live
)
3675 /* The register may have been conditionally live previously, but
3676 is now unconditionally live. Remove it from the conditionally
3677 dead list, so that a conditional set won't cause us to think
3679 splay_tree_remove (pbi
->reg_cond_dead
, i
);
3685 /* Scan expression X and store a 1-bit in NEW_LIVE for each reg it uses.
3686 This is done assuming the registers needed from X are those that
3687 have 1-bits in PBI->REG_LIVE.
3689 INSN is the containing instruction. If INSN is dead, this function
3693 mark_used_regs (struct propagate_block_info
*pbi
, rtx x
, rtx cond
, rtx insn
)
3697 int flags
= pbi
->flags
;
3702 code
= GET_CODE (x
);
3723 /* If we are clobbering a MEM, mark any registers inside the address
3725 if (MEM_P (XEXP (x
, 0)))
3726 mark_used_regs (pbi
, XEXP (XEXP (x
, 0), 0), cond
, insn
);
3730 /* Don't bother watching stores to mems if this is not the
3731 final pass. We'll not be deleting dead stores this round. */
3732 if (optimize
&& (flags
& PROP_SCAN_DEAD_STORES
))
3734 /* Invalidate the data for the last MEM stored, but only if MEM is
3735 something that can be stored into. */
3736 if (GET_CODE (XEXP (x
, 0)) == SYMBOL_REF
3737 && CONSTANT_POOL_ADDRESS_P (XEXP (x
, 0)))
3738 /* Needn't clear the memory set list. */
3742 rtx temp
= pbi
->mem_set_list
;
3743 rtx prev
= NULL_RTX
;
3748 next
= XEXP (temp
, 1);
3749 if (anti_dependence (XEXP (temp
, 0), x
))
3751 /* Splice temp out of the list. */
3753 XEXP (prev
, 1) = next
;
3755 pbi
->mem_set_list
= next
;
3756 free_EXPR_LIST_node (temp
);
3757 pbi
->mem_set_list_len
--;
3765 /* If the memory reference had embedded side effects (autoincrement
3766 address modes. Then we may need to kill some entries on the
3769 for_each_rtx (&PATTERN (insn
), invalidate_mems_from_autoinc
, pbi
);
3773 if (flags
& PROP_AUTOINC
)
3774 find_auto_inc (pbi
, x
, insn
);
3779 #ifdef CANNOT_CHANGE_MODE_CLASS
3780 if (flags
& PROP_REG_INFO
)
3781 record_subregs_of_mode (x
);
3784 /* While we're here, optimize this case. */
3791 /* See a register other than being set => mark it as needed. */
3792 mark_used_reg (pbi
, x
, cond
, insn
);
3797 rtx testreg
= SET_DEST (x
);
3800 /* If storing into MEM, don't show it as being used. But do
3801 show the address as being used. */
3802 if (MEM_P (testreg
))
3805 if (flags
& PROP_AUTOINC
)
3806 find_auto_inc (pbi
, testreg
, insn
);
3808 mark_used_regs (pbi
, XEXP (testreg
, 0), cond
, insn
);
3809 mark_used_regs (pbi
, SET_SRC (x
), cond
, insn
);
3813 /* Storing in STRICT_LOW_PART is like storing in a reg
3814 in that this SET might be dead, so ignore it in TESTREG.
3815 but in some other ways it is like using the reg.
3817 Storing in a SUBREG or a bit field is like storing the entire
3818 register in that if the register's value is not used
3819 then this SET is not needed. */
3820 while (GET_CODE (testreg
) == STRICT_LOW_PART
3821 || GET_CODE (testreg
) == ZERO_EXTRACT
3822 || GET_CODE (testreg
) == SIGN_EXTRACT
3823 || GET_CODE (testreg
) == SUBREG
)
3825 #ifdef CANNOT_CHANGE_MODE_CLASS
3826 if ((flags
& PROP_REG_INFO
) && GET_CODE (testreg
) == SUBREG
)
3827 record_subregs_of_mode (testreg
);
3830 /* Modifying a single register in an alternate mode
3831 does not use any of the old value. But these other
3832 ways of storing in a register do use the old value. */
3833 if (GET_CODE (testreg
) == SUBREG
3834 && !((REG_BYTES (SUBREG_REG (testreg
))
3835 + UNITS_PER_WORD
- 1) / UNITS_PER_WORD
3836 > (REG_BYTES (testreg
)
3837 + UNITS_PER_WORD
- 1) / UNITS_PER_WORD
))
3842 testreg
= XEXP (testreg
, 0);
3845 /* If this is a store into a register or group of registers,
3846 recursively scan the value being stored. */
3848 if ((GET_CODE (testreg
) == PARALLEL
3849 && GET_MODE (testreg
) == BLKmode
)
3851 && (regno
= REGNO (testreg
),
3852 ! (regno
== FRAME_POINTER_REGNUM
3853 && (! reload_completed
|| frame_pointer_needed
)))
3854 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
3855 && ! (regno
== HARD_FRAME_POINTER_REGNUM
3856 && (! reload_completed
|| frame_pointer_needed
))
3858 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
3859 && ! (regno
== ARG_POINTER_REGNUM
&& fixed_regs
[regno
])
3864 mark_used_regs (pbi
, SET_DEST (x
), cond
, insn
);
3865 mark_used_regs (pbi
, SET_SRC (x
), cond
, insn
);
3872 case UNSPEC_VOLATILE
:
3876 /* Traditional and volatile asm instructions must be considered to use
3877 and clobber all hard registers, all pseudo-registers and all of
3878 memory. So must TRAP_IF and UNSPEC_VOLATILE operations.
3880 Consider for instance a volatile asm that changes the fpu rounding
3881 mode. An insn should not be moved across this even if it only uses
3882 pseudo-regs because it might give an incorrectly rounded result.
3884 ?!? Unfortunately, marking all hard registers as live causes massive
3885 problems for the register allocator and marking all pseudos as live
3886 creates mountains of uninitialized variable warnings.
3888 So for now, just clear the memory set list and mark any regs
3889 we can find in ASM_OPERANDS as used. */
3890 if (code
!= ASM_OPERANDS
|| MEM_VOLATILE_P (x
))
3892 free_EXPR_LIST_list (&pbi
->mem_set_list
);
3893 pbi
->mem_set_list_len
= 0;
3896 /* For all ASM_OPERANDS, we must traverse the vector of input operands.
3897 We can not just fall through here since then we would be confused
3898 by the ASM_INPUT rtx inside ASM_OPERANDS, which do not indicate
3899 traditional asms unlike their normal usage. */
3900 if (code
== ASM_OPERANDS
)
3904 for (j
= 0; j
< ASM_OPERANDS_INPUT_LENGTH (x
); j
++)
3905 mark_used_regs (pbi
, ASM_OPERANDS_INPUT (x
, j
), cond
, insn
);
3913 mark_used_regs (pbi
, COND_EXEC_TEST (x
), NULL_RTX
, insn
);
3915 cond
= COND_EXEC_TEST (x
);
3916 x
= COND_EXEC_CODE (x
);
3923 /* Recursively scan the operands of this expression. */
3926 const char * const fmt
= GET_RTX_FORMAT (code
);
3929 for (i
= GET_RTX_LENGTH (code
) - 1; i
>= 0; i
--)
3933 /* Tail recursive case: save a function call level. */
3939 mark_used_regs (pbi
, XEXP (x
, i
), cond
, insn
);
3941 else if (fmt
[i
] == 'E')
3944 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
3945 mark_used_regs (pbi
, XVECEXP (x
, i
, j
), cond
, insn
);
3954 try_pre_increment_1 (struct propagate_block_info
*pbi
, rtx insn
)
3956 /* Find the next use of this reg. If in same basic block,
3957 make it do pre-increment or pre-decrement if appropriate. */
3958 rtx x
= single_set (insn
);
3959 HOST_WIDE_INT amount
= ((GET_CODE (SET_SRC (x
)) == PLUS
? 1 : -1)
3960 * INTVAL (XEXP (SET_SRC (x
), 1)));
3961 int regno
= REGNO (SET_DEST (x
));
3962 rtx y
= pbi
->reg_next_use
[regno
];
3964 && SET_DEST (x
) != stack_pointer_rtx
3965 && BLOCK_NUM (y
) == BLOCK_NUM (insn
)
3966 /* Don't do this if the reg dies, or gets set in y; a standard addressing
3967 mode would be better. */
3968 && ! dead_or_set_p (y
, SET_DEST (x
))
3969 && try_pre_increment (y
, SET_DEST (x
), amount
))
3971 /* We have found a suitable auto-increment and already changed
3972 insn Y to do it. So flush this increment instruction. */
3973 propagate_block_delete_insn (insn
);
3975 /* Count a reference to this reg for the increment insn we are
3976 deleting. When a reg is incremented, spilling it is worse,
3977 so we want to make that less likely. */
3978 if (regno
>= FIRST_PSEUDO_REGISTER
)
3980 REG_FREQ (regno
) += REG_FREQ_FROM_BB (pbi
->bb
);
3981 REG_N_SETS (regno
)++;
3984 /* Flush any remembered memories depending on the value of
3985 the incremented register. */
3986 invalidate_mems_from_set (pbi
, SET_DEST (x
));
3993 /* Try to change INSN so that it does pre-increment or pre-decrement
3994 addressing on register REG in order to add AMOUNT to REG.
3995 AMOUNT is negative for pre-decrement.
3996 Returns 1 if the change could be made.
3997 This checks all about the validity of the result of modifying INSN. */
4000 try_pre_increment (rtx insn
, rtx reg
, HOST_WIDE_INT amount
)
4004 /* Nonzero if we can try to make a pre-increment or pre-decrement.
4005 For example, addl $4,r1; movl (r1),... can become movl +(r1),... */
4007 /* Nonzero if we can try to make a post-increment or post-decrement.
4008 For example, addl $4,r1; movl -4(r1),... can become movl (r1)+,...
4009 It is possible for both PRE_OK and POST_OK to be nonzero if the machine
4010 supports both pre-inc and post-inc, or both pre-dec and post-dec. */
4013 /* Nonzero if the opportunity actually requires post-inc or post-dec. */
4016 /* From the sign of increment, see which possibilities are conceivable
4017 on this target machine. */
4018 if (HAVE_PRE_INCREMENT
&& amount
> 0)
4020 if (HAVE_POST_INCREMENT
&& amount
> 0)
4023 if (HAVE_PRE_DECREMENT
&& amount
< 0)
4025 if (HAVE_POST_DECREMENT
&& amount
< 0)
4028 if (! (pre_ok
|| post_ok
))
4031 /* It is not safe to add a side effect to a jump insn
4032 because if the incremented register is spilled and must be reloaded
4033 there would be no way to store the incremented value back in memory. */
4040 use
= find_use_as_address (PATTERN (insn
), reg
, 0);
4041 if (post_ok
&& (use
== 0 || use
== (rtx
) (size_t) 1))
4043 use
= find_use_as_address (PATTERN (insn
), reg
, -amount
);
4047 if (use
== 0 || use
== (rtx
) (size_t) 1)
4050 if (GET_MODE_SIZE (GET_MODE (use
)) != (amount
> 0 ? amount
: - amount
))
4053 /* See if this combination of instruction and addressing mode exists. */
4054 if (! validate_change (insn
, &XEXP (use
, 0),
4055 gen_rtx_fmt_e (amount
> 0
4056 ? (do_post
? POST_INC
: PRE_INC
)
4057 : (do_post
? POST_DEC
: PRE_DEC
),
4061 /* Record that this insn now has an implicit side effect on X. */
4062 REG_NOTES (insn
) = alloc_EXPR_LIST (REG_INC
, reg
, REG_NOTES (insn
));
4066 #endif /* AUTO_INC_DEC */
4068 /* Find the place in the rtx X where REG is used as a memory address.
4069 Return the MEM rtx that so uses it.
4070 If PLUSCONST is nonzero, search instead for a memory address equivalent to
4071 (plus REG (const_int PLUSCONST)).
4073 If such an address does not appear, return 0.
4074 If REG appears more than once, or is used other than in such an address,
4078 find_use_as_address (rtx x
, rtx reg
, HOST_WIDE_INT plusconst
)
4080 enum rtx_code code
= GET_CODE (x
);
4081 const char * const fmt
= GET_RTX_FORMAT (code
);
4086 if (code
== MEM
&& XEXP (x
, 0) == reg
&& plusconst
== 0)
4089 if (code
== MEM
&& GET_CODE (XEXP (x
, 0)) == PLUS
4090 && XEXP (XEXP (x
, 0), 0) == reg
4091 && GET_CODE (XEXP (XEXP (x
, 0), 1)) == CONST_INT
4092 && INTVAL (XEXP (XEXP (x
, 0), 1)) == plusconst
)
4095 if (code
== SIGN_EXTRACT
|| code
== ZERO_EXTRACT
)
4097 /* If REG occurs inside a MEM used in a bit-field reference,
4098 that is unacceptable. */
4099 if (find_use_as_address (XEXP (x
, 0), reg
, 0) != 0)
4100 return (rtx
) (size_t) 1;
4104 return (rtx
) (size_t) 1;
4106 for (i
= GET_RTX_LENGTH (code
) - 1; i
>= 0; i
--)
4110 tem
= find_use_as_address (XEXP (x
, i
), reg
, plusconst
);
4114 return (rtx
) (size_t) 1;
4116 else if (fmt
[i
] == 'E')
4119 for (j
= XVECLEN (x
, i
) - 1; j
>= 0; j
--)
4121 tem
= find_use_as_address (XVECEXP (x
, i
, j
), reg
, plusconst
);
4125 return (rtx
) (size_t) 1;
4133 /* Write information about registers and basic blocks into FILE.
4134 This is part of making a debugging dump. */
4137 dump_regset (regset r
, FILE *outf
)
4140 reg_set_iterator rsi
;
4144 fputs (" (nil)", outf
);
4148 EXECUTE_IF_SET_IN_REG_SET (r
, 0, i
, rsi
)
4150 fprintf (outf
, " %d", i
);
4151 if (i
< FIRST_PSEUDO_REGISTER
)
4152 fprintf (outf
, " [%s]",
4157 /* Print a human-readable representation of R on the standard error
4158 stream. This function is designed to be used from within the
4162 debug_regset (regset r
)
4164 dump_regset (r
, stderr
);
4165 putc ('\n', stderr
);
4168 /* Recompute register set/reference counts immediately prior to register
4171 This avoids problems with set/reference counts changing to/from values
4172 which have special meanings to the register allocators.
4174 Additionally, the reference counts are the primary component used by the
4175 register allocators to prioritize pseudos for allocation to hard regs.
4176 More accurate reference counts generally lead to better register allocation.
4178 F is the first insn to be scanned.
4180 LOOP_STEP denotes how much loop_depth should be incremented per
4181 loop nesting level in order to increase the ref count more for
4182 references in a loop.
4184 It might be worthwhile to update REG_LIVE_LENGTH, REG_BASIC_BLOCK and
4185 possibly other information which is used by the register allocators. */
4188 recompute_reg_usage (rtx f ATTRIBUTE_UNUSED
, int loop_step ATTRIBUTE_UNUSED
)
4190 allocate_reg_life_data ();
4191 /* distribute_notes in combiner fails to convert some of the REG_UNUSED notes
4192 to REG_DEAD notes. This causes CHECK_DEAD_NOTES in sched1 to abort. To
4193 solve this update the DEATH_NOTES here. */
4194 update_life_info (NULL
, UPDATE_LIFE_LOCAL
, PROP_REG_INFO
| PROP_DEATH_NOTES
);
4197 /* Optionally removes all the REG_DEAD and REG_UNUSED notes from a set of
4198 blocks. If BLOCKS is NULL, assume the universal set. Returns a count
4199 of the number of registers that died. */
4202 count_or_remove_death_notes (sbitmap blocks
, int kill
)
4208 /* This used to be a loop over all the blocks with a membership test
4209 inside the loop. That can be amazingly expensive on a large CFG
4210 when only a small number of bits are set in BLOCKs (for example,
4211 the calls from the scheduler typically have very few bits set).
4213 For extra credit, someone should convert BLOCKS to a bitmap rather
4217 EXECUTE_IF_SET_IN_SBITMAP (blocks
, 0, i
,
4219 count
+= count_or_remove_death_notes_bb (BASIC_BLOCK (i
), kill
);
4226 count
+= count_or_remove_death_notes_bb (bb
, kill
);
4233 /* Optionally removes all the REG_DEAD and REG_UNUSED notes from basic
4234 block BB. Returns a count of the number of registers that died. */
4237 count_or_remove_death_notes_bb (basic_block bb
, int kill
)
4242 for (insn
= BB_HEAD (bb
); ; insn
= NEXT_INSN (insn
))
4246 rtx
*pprev
= ®_NOTES (insn
);
4251 switch (REG_NOTE_KIND (link
))
4254 if (REG_P (XEXP (link
, 0)))
4256 rtx reg
= XEXP (link
, 0);
4259 if (REGNO (reg
) >= FIRST_PSEUDO_REGISTER
)
4262 n
= hard_regno_nregs
[REGNO (reg
)][GET_MODE (reg
)];
4271 rtx next
= XEXP (link
, 1);
4272 free_EXPR_LIST_node (link
);
4273 *pprev
= link
= next
;
4279 pprev
= &XEXP (link
, 1);
4286 if (insn
== BB_END (bb
))
4293 /* Clear LOG_LINKS fields of insns in a selected blocks or whole chain
4294 if blocks is NULL. */
4297 clear_log_links (sbitmap blocks
)
4304 for (insn
= get_insns (); insn
; insn
= NEXT_INSN (insn
))
4306 free_INSN_LIST_list (&LOG_LINKS (insn
));
4309 EXECUTE_IF_SET_IN_SBITMAP (blocks
, 0, i
,
4311 basic_block bb
= BASIC_BLOCK (i
);
4313 for (insn
= BB_HEAD (bb
); insn
!= NEXT_INSN (BB_END (bb
));
4314 insn
= NEXT_INSN (insn
))
4316 free_INSN_LIST_list (&LOG_LINKS (insn
));
4320 /* Given a register bitmap, turn on the bits in a HARD_REG_SET that
4321 correspond to the hard registers, if any, set in that map. This
4322 could be done far more efficiently by having all sorts of special-cases
4323 with moving single words, but probably isn't worth the trouble. */
4326 reg_set_to_hard_reg_set (HARD_REG_SET
*to
, bitmap from
)
4331 EXECUTE_IF_SET_IN_BITMAP (from
, 0, i
, bi
)
4333 if (i
>= FIRST_PSEUDO_REGISTER
)
4335 SET_HARD_REG_BIT (*to
, i
);