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
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
,
575 int stabilized_prop_flags
= prop_flags
;
578 tmp
= OBSTACK_ALLOC_REG_SET (®_obstack
);
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
;
1020 /* The registers that are modified within this in block. */
1023 /* The registers that are conditionally modified within this block.
1024 In other words, regs that are set only as part of a COND_EXEC. */
1025 regset
*cond_local_sets
;
1029 /* Some passes used to forget clear aux field of basic block causing
1030 sick behavior here. */
1031 #ifdef ENABLE_CHECKING
1032 FOR_BB_BETWEEN (bb
, ENTRY_BLOCK_PTR
, NULL
, next_bb
)
1033 gcc_assert (!bb
->aux
);
1036 tmp
= OBSTACK_ALLOC_REG_SET (®_obstack
);
1037 new_live_at_end
= OBSTACK_ALLOC_REG_SET (®_obstack
);
1038 invalidated_by_call
= OBSTACK_ALLOC_REG_SET (®_obstack
);
1040 /* Inconveniently, this is only readily available in hard reg set form. */
1041 for (i
= 0; i
< FIRST_PSEUDO_REGISTER
; ++i
)
1042 if (TEST_HARD_REG_BIT (regs_invalidated_by_call
, i
))
1043 SET_REGNO_REG_SET (invalidated_by_call
, i
);
1045 /* Allocate space for the sets of local properties. */
1046 local_sets
= xcalloc (last_basic_block
- (INVALID_BLOCK
+ 1),
1048 cond_local_sets
= xcalloc (last_basic_block
- (INVALID_BLOCK
+ 1),
1051 /* Create a worklist. Allocate an extra slot for ENTRY_BLOCK, and one
1052 because the `head == tail' style test for an empty queue doesn't
1053 work with a full queue. */
1054 queue
= xmalloc ((n_basic_blocks
- (INVALID_BLOCK
+ 1)) * sizeof (*queue
));
1056 qhead
= qend
= queue
+ n_basic_blocks
- (INVALID_BLOCK
+ 1);
1058 /* Queue the blocks set in the initial mask. Do this in reverse block
1059 number order so that we are more likely for the first round to do
1060 useful work. We use AUX non-null to flag that the block is queued. */
1064 if (TEST_BIT (blocks_in
, bb
->index
))
1079 /* We clean aux when we remove the initially-enqueued bbs, but we
1080 don't enqueue ENTRY and EXIT initially, so clean them upfront and
1082 ENTRY_BLOCK_PTR
->aux
= EXIT_BLOCK_PTR
->aux
= NULL
;
1085 sbitmap_zero (blocks_out
);
1087 /* We work through the queue until there are no more blocks. What
1088 is live at the end of this block is precisely the union of what
1089 is live at the beginning of all its successors. So, we set its
1090 GLOBAL_LIVE_AT_END field based on the GLOBAL_LIVE_AT_START field
1091 for its successors. Then, we compute GLOBAL_LIVE_AT_START for
1092 this block by walking through the instructions in this block in
1093 reverse order and updating as we go. If that changed
1094 GLOBAL_LIVE_AT_START, we add the predecessors of the block to the
1095 queue; they will now need to recalculate GLOBAL_LIVE_AT_END.
1097 We are guaranteed to terminate, because GLOBAL_LIVE_AT_START
1098 never shrinks. If a register appears in GLOBAL_LIVE_AT_START, it
1099 must either be live at the end of the block, or used within the
1100 block. In the latter case, it will certainly never disappear
1101 from GLOBAL_LIVE_AT_START. In the former case, the register
1102 could go away only if it disappeared from GLOBAL_LIVE_AT_START
1103 for one of the successor blocks. By induction, that cannot
1105 while (qhead
!= qtail
)
1107 int rescan
, changed
;
1117 /* Begin by propagating live_at_start from the successor blocks. */
1118 CLEAR_REG_SET (new_live_at_end
);
1120 if (EDGE_COUNT (bb
->succs
) > 0)
1121 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
1123 basic_block sb
= e
->dest
;
1125 /* Call-clobbered registers die across exception and
1127 /* ??? Abnormal call edges ignored for the moment, as this gets
1128 confused by sibling call edges, which crashes reg-stack. */
1129 if (e
->flags
& EDGE_EH
)
1130 bitmap_ior_and_compl_into (new_live_at_end
,
1131 sb
->global_live_at_start
,
1132 invalidated_by_call
);
1134 IOR_REG_SET (new_live_at_end
, sb
->global_live_at_start
);
1136 /* If a target saves one register in another (instead of on
1137 the stack) the save register will need to be live for EH. */
1138 if (e
->flags
& EDGE_EH
)
1139 for (i
= 0; i
< FIRST_PSEUDO_REGISTER
; i
++)
1141 SET_REGNO_REG_SET (new_live_at_end
, i
);
1145 /* This might be a noreturn function that throws. And
1146 even if it isn't, getting the unwind info right helps
1148 for (i
= 0; i
< FIRST_PSEUDO_REGISTER
; i
++)
1150 SET_REGNO_REG_SET (new_live_at_end
, i
);
1153 /* The all-important stack pointer must always be live. */
1154 SET_REGNO_REG_SET (new_live_at_end
, STACK_POINTER_REGNUM
);
1156 /* Before reload, there are a few registers that must be forced
1157 live everywhere -- which might not already be the case for
1158 blocks within infinite loops. */
1159 if (! reload_completed
)
1161 /* Any reference to any pseudo before reload is a potential
1162 reference of the frame pointer. */
1163 SET_REGNO_REG_SET (new_live_at_end
, FRAME_POINTER_REGNUM
);
1165 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
1166 /* Pseudos with argument area equivalences may require
1167 reloading via the argument pointer. */
1168 if (fixed_regs
[ARG_POINTER_REGNUM
])
1169 SET_REGNO_REG_SET (new_live_at_end
, ARG_POINTER_REGNUM
);
1172 /* Any constant, or pseudo with constant equivalences, may
1173 require reloading from memory using the pic register. */
1174 if ((unsigned) PIC_OFFSET_TABLE_REGNUM
!= INVALID_REGNUM
1175 && fixed_regs
[PIC_OFFSET_TABLE_REGNUM
])
1176 SET_REGNO_REG_SET (new_live_at_end
, PIC_OFFSET_TABLE_REGNUM
);
1179 if (bb
== ENTRY_BLOCK_PTR
)
1181 COPY_REG_SET (bb
->global_live_at_end
, new_live_at_end
);
1185 /* On our first pass through this block, we'll go ahead and continue.
1186 Recognize first pass by checking if local_set is NULL for this
1187 basic block. On subsequent passes, we get to skip out early if
1188 live_at_end wouldn't have changed. */
1190 if (local_sets
[bb
->index
- (INVALID_BLOCK
+ 1)] == NULL
)
1192 local_sets
[bb
->index
- (INVALID_BLOCK
+ 1)] = XMALLOC_REG_SET ();
1193 cond_local_sets
[bb
->index
- (INVALID_BLOCK
+ 1)] = XMALLOC_REG_SET ();
1198 /* If any bits were removed from live_at_end, we'll have to
1199 rescan the block. This wouldn't be necessary if we had
1200 precalculated local_live, however with PROP_SCAN_DEAD_CODE
1201 local_live is really dependent on live_at_end. */
1202 rescan
= bitmap_intersect_compl_p (bb
->global_live_at_end
,
1207 regset cond_local_set
;
1209 /* If any of the registers in the new live_at_end set are
1210 conditionally set in this basic block, we must rescan.
1211 This is because conditional lifetimes at the end of the
1212 block do not just take the live_at_end set into
1213 account, but also the liveness at the start of each
1214 successor block. We can miss changes in those sets if
1215 we only compare the new live_at_end against the
1217 cond_local_set
= cond_local_sets
[bb
->index
- (INVALID_BLOCK
+ 1)];
1218 rescan
= bitmap_intersect_p (new_live_at_end
, cond_local_set
);
1225 /* Find the set of changed bits. Take this opportunity
1226 to notice that this set is empty and early out. */
1227 bitmap_xor (tmp
, bb
->global_live_at_end
, new_live_at_end
);
1228 if (bitmap_empty_p (tmp
))
1231 /* If any of the changed bits overlap with local_sets[bb],
1232 we'll have to rescan the block. */
1233 local_set
= local_sets
[bb
->index
- (INVALID_BLOCK
+ 1)];
1234 rescan
= bitmap_intersect_p (tmp
, local_set
);
1238 /* Let our caller know that BB changed enough to require its
1239 death notes updated. */
1241 SET_BIT (blocks_out
, bb
->index
);
1245 /* Add to live_at_start the set of all registers in
1246 new_live_at_end that aren't in the old live_at_end. */
1248 changed
= bitmap_ior_and_compl_into (bb
->global_live_at_start
,
1250 bb
->global_live_at_end
);
1251 COPY_REG_SET (bb
->global_live_at_end
, new_live_at_end
);
1257 COPY_REG_SET (bb
->global_live_at_end
, new_live_at_end
);
1259 /* Rescan the block insn by insn to turn (a copy of) live_at_end
1260 into live_at_start. */
1261 propagate_block (bb
, new_live_at_end
,
1262 local_sets
[bb
->index
- (INVALID_BLOCK
+ 1)],
1263 cond_local_sets
[bb
->index
- (INVALID_BLOCK
+ 1)],
1266 /* If live_at start didn't change, no need to go farther. */
1267 if (REG_SET_EQUAL_P (bb
->global_live_at_start
, new_live_at_end
))
1270 COPY_REG_SET (bb
->global_live_at_start
, new_live_at_end
);
1273 /* Queue all predecessors of BB so that we may re-examine
1274 their live_at_end. */
1275 FOR_EACH_EDGE (e
, ei
, bb
->preds
)
1277 basic_block pb
= e
->src
;
1278 if (pb
->aux
== NULL
)
1289 FREE_REG_SET (new_live_at_end
);
1290 FREE_REG_SET (invalidated_by_call
);
1294 EXECUTE_IF_SET_IN_SBITMAP (blocks_out
, 0, i
,
1296 basic_block bb
= BASIC_BLOCK (i
);
1297 XFREE_REG_SET (local_sets
[bb
->index
- (INVALID_BLOCK
+ 1)]);
1298 XFREE_REG_SET (cond_local_sets
[bb
->index
- (INVALID_BLOCK
+ 1)]);
1305 XFREE_REG_SET (local_sets
[bb
->index
- (INVALID_BLOCK
+ 1)]);
1306 XFREE_REG_SET (cond_local_sets
[bb
->index
- (INVALID_BLOCK
+ 1)]);
1311 free (cond_local_sets
);
1316 /* This structure is used to pass parameters to and from the
1317 the function find_regno_partial(). It is used to pass in the
1318 register number we are looking, as well as to return any rtx
1322 unsigned regno_to_find
;
1324 } find_regno_partial_param
;
1327 /* Find the rtx for the reg numbers specified in 'data' if it is
1328 part of an expression which only uses part of the register. Return
1329 it in the structure passed in. */
1331 find_regno_partial (rtx
*ptr
, void *data
)
1333 find_regno_partial_param
*param
= (find_regno_partial_param
*)data
;
1334 unsigned reg
= param
->regno_to_find
;
1335 param
->retval
= NULL_RTX
;
1337 if (*ptr
== NULL_RTX
)
1340 switch (GET_CODE (*ptr
))
1344 case STRICT_LOW_PART
:
1345 if (REG_P (XEXP (*ptr
, 0)) && REGNO (XEXP (*ptr
, 0)) == reg
)
1347 param
->retval
= XEXP (*ptr
, 0);
1353 if (REG_P (SUBREG_REG (*ptr
))
1354 && REGNO (SUBREG_REG (*ptr
)) == reg
)
1356 param
->retval
= SUBREG_REG (*ptr
);
1368 /* Process all immediate successors of the entry block looking for pseudo
1369 registers which are live on entry. Find all of those whose first
1370 instance is a partial register reference of some kind, and initialize
1371 them to 0 after the entry block. This will prevent bit sets within
1372 registers whose value is unknown, and may contain some kind of sticky
1373 bits we don't want. */
1376 initialize_uninitialized_subregs (void)
1380 unsigned reg
, did_something
= 0;
1381 find_regno_partial_param param
;
1384 FOR_EACH_EDGE (e
, ei
, ENTRY_BLOCK_PTR
->succs
)
1386 basic_block bb
= e
->dest
;
1387 regset map
= bb
->global_live_at_start
;
1388 reg_set_iterator rsi
;
1390 EXECUTE_IF_SET_IN_REG_SET (map
, FIRST_PSEUDO_REGISTER
, reg
, rsi
)
1392 int uid
= REGNO_FIRST_UID (reg
);
1395 /* Find an insn which mentions the register we are looking for.
1396 Its preferable to have an instance of the register's rtl since
1397 there may be various flags set which we need to duplicate.
1398 If we can't find it, its probably an automatic whose initial
1399 value doesn't matter, or hopefully something we don't care about. */
1400 for (i
= get_insns (); i
&& INSN_UID (i
) != uid
; i
= NEXT_INSN (i
))
1404 /* Found the insn, now get the REG rtx, if we can. */
1405 param
.regno_to_find
= reg
;
1406 for_each_rtx (&i
, find_regno_partial
, ¶m
);
1407 if (param
.retval
!= NULL_RTX
)
1410 emit_move_insn (param
.retval
,
1411 CONST0_RTX (GET_MODE (param
.retval
)));
1412 insn
= get_insns ();
1414 insert_insn_on_edge (insn
, e
);
1422 commit_edge_insertions ();
1423 return did_something
;
1427 /* Subroutines of life analysis. */
1429 /* Allocate the permanent data structures that represent the results
1430 of life analysis. */
1433 allocate_bb_life_data (void)
1437 FOR_BB_BETWEEN (bb
, ENTRY_BLOCK_PTR
, NULL
, next_bb
)
1439 bb
->global_live_at_start
= OBSTACK_ALLOC_REG_SET (®_obstack
);
1440 bb
->global_live_at_end
= OBSTACK_ALLOC_REG_SET (®_obstack
);
1443 regs_live_at_setjmp
= OBSTACK_ALLOC_REG_SET (®_obstack
);
1447 allocate_reg_life_data (void)
1451 max_regno
= max_reg_num ();
1452 gcc_assert (!reg_deaths
);
1453 reg_deaths
= xcalloc (sizeof (*reg_deaths
), max_regno
);
1455 /* Recalculate the register space, in case it has grown. Old style
1456 vector oriented regsets would set regset_{size,bytes} here also. */
1457 allocate_reg_info (max_regno
, FALSE
, FALSE
);
1459 /* Reset all the data we'll collect in propagate_block and its
1461 for (i
= 0; i
< max_regno
; i
++)
1465 REG_N_DEATHS (i
) = 0;
1466 REG_N_CALLS_CROSSED (i
) = 0;
1467 REG_LIVE_LENGTH (i
) = 0;
1469 REG_BASIC_BLOCK (i
) = REG_BLOCK_UNKNOWN
;
1473 /* Delete dead instructions for propagate_block. */
1476 propagate_block_delete_insn (rtx insn
)
1478 rtx inote
= find_reg_note (insn
, REG_LABEL
, NULL_RTX
);
1480 /* If the insn referred to a label, and that label was attached to
1481 an ADDR_VEC, it's safe to delete the ADDR_VEC. In fact, it's
1482 pretty much mandatory to delete it, because the ADDR_VEC may be
1483 referencing labels that no longer exist.
1485 INSN may reference a deleted label, particularly when a jump
1486 table has been optimized into a direct jump. There's no
1487 real good way to fix up the reference to the deleted label
1488 when the label is deleted, so we just allow it here. */
1490 if (inote
&& LABEL_P (inote
))
1492 rtx label
= XEXP (inote
, 0);
1495 /* The label may be forced if it has been put in the constant
1496 pool. If that is the only use we must discard the table
1497 jump following it, but not the label itself. */
1498 if (LABEL_NUSES (label
) == 1 + LABEL_PRESERVE_P (label
)
1499 && (next
= next_nonnote_insn (label
)) != NULL
1501 && (GET_CODE (PATTERN (next
)) == ADDR_VEC
1502 || GET_CODE (PATTERN (next
)) == ADDR_DIFF_VEC
))
1504 rtx pat
= PATTERN (next
);
1505 int diff_vec_p
= GET_CODE (pat
) == ADDR_DIFF_VEC
;
1506 int len
= XVECLEN (pat
, diff_vec_p
);
1509 for (i
= 0; i
< len
; i
++)
1510 LABEL_NUSES (XEXP (XVECEXP (pat
, diff_vec_p
, i
), 0))--;
1512 delete_insn_and_edges (next
);
1517 delete_insn_and_edges (insn
);
1521 /* Delete dead libcalls for propagate_block. Return the insn
1522 before the libcall. */
1525 propagate_block_delete_libcall (rtx insn
, rtx note
)
1527 rtx first
= XEXP (note
, 0);
1528 rtx before
= PREV_INSN (first
);
1530 delete_insn_chain_and_edges (first
, insn
);
1535 /* Update the life-status of regs for one insn. Return the previous insn. */
1538 propagate_one_insn (struct propagate_block_info
*pbi
, rtx insn
)
1540 rtx prev
= PREV_INSN (insn
);
1541 int flags
= pbi
->flags
;
1542 int insn_is_dead
= 0;
1543 int libcall_is_dead
= 0;
1547 if (! INSN_P (insn
))
1550 note
= find_reg_note (insn
, REG_RETVAL
, NULL_RTX
);
1551 if (flags
& PROP_SCAN_DEAD_CODE
)
1553 insn_is_dead
= insn_dead_p (pbi
, PATTERN (insn
), 0, REG_NOTES (insn
));
1554 libcall_is_dead
= (insn_is_dead
&& note
!= 0
1555 && libcall_dead_p (pbi
, note
, insn
));
1558 /* If an instruction consists of just dead store(s) on final pass,
1560 if ((flags
& PROP_KILL_DEAD_CODE
) && insn_is_dead
)
1562 /* If we're trying to delete a prologue or epilogue instruction
1563 that isn't flagged as possibly being dead, something is wrong.
1564 But if we are keeping the stack pointer depressed, we might well
1565 be deleting insns that are used to compute the amount to update
1566 it by, so they are fine. */
1567 if (reload_completed
1568 && !(TREE_CODE (TREE_TYPE (current_function_decl
)) == FUNCTION_TYPE
1569 && (TYPE_RETURNS_STACK_DEPRESSED
1570 (TREE_TYPE (current_function_decl
))))
1571 && (((HAVE_epilogue
|| HAVE_prologue
)
1572 && prologue_epilogue_contains (insn
))
1573 || (HAVE_sibcall_epilogue
1574 && sibcall_epilogue_contains (insn
)))
1575 && find_reg_note (insn
, REG_MAYBE_DEAD
, NULL_RTX
) == 0)
1576 fatal_insn ("Attempt to delete prologue/epilogue insn:", insn
);
1578 /* Record sets. Do this even for dead instructions, since they
1579 would have killed the values if they hadn't been deleted. */
1580 mark_set_regs (pbi
, PATTERN (insn
), insn
);
1582 /* CC0 is now known to be dead. Either this insn used it,
1583 in which case it doesn't anymore, or clobbered it,
1584 so the next insn can't use it. */
1587 if (libcall_is_dead
)
1588 prev
= propagate_block_delete_libcall ( insn
, note
);
1592 /* If INSN contains a RETVAL note and is dead, but the libcall
1593 as a whole is not dead, then we want to remove INSN, but
1594 not the whole libcall sequence.
1596 However, we need to also remove the dangling REG_LIBCALL
1597 note so that we do not have mis-matched LIBCALL/RETVAL
1598 notes. In theory we could find a new location for the
1599 REG_RETVAL note, but it hardly seems worth the effort.
1601 NOTE at this point will be the RETVAL note if it exists. */
1607 = find_reg_note (XEXP (note
, 0), REG_LIBCALL
, NULL_RTX
);
1608 remove_note (XEXP (note
, 0), libcall_note
);
1611 /* Similarly if INSN contains a LIBCALL note, remove the
1612 dangling REG_RETVAL note. */
1613 note
= find_reg_note (insn
, REG_LIBCALL
, NULL_RTX
);
1619 = find_reg_note (XEXP (note
, 0), REG_RETVAL
, NULL_RTX
);
1620 remove_note (XEXP (note
, 0), retval_note
);
1623 /* Now delete INSN. */
1624 propagate_block_delete_insn (insn
);
1630 /* See if this is an increment or decrement that can be merged into
1631 a following memory address. */
1634 rtx x
= single_set (insn
);
1636 /* Does this instruction increment or decrement a register? */
1637 if ((flags
& PROP_AUTOINC
)
1639 && REG_P (SET_DEST (x
))
1640 && (GET_CODE (SET_SRC (x
)) == PLUS
1641 || GET_CODE (SET_SRC (x
)) == MINUS
)
1642 && XEXP (SET_SRC (x
), 0) == SET_DEST (x
)
1643 && GET_CODE (XEXP (SET_SRC (x
), 1)) == CONST_INT
1644 /* Ok, look for a following memory ref we can combine with.
1645 If one is found, change the memory ref to a PRE_INC
1646 or PRE_DEC, cancel this insn, and return 1.
1647 Return 0 if nothing has been done. */
1648 && try_pre_increment_1 (pbi
, insn
))
1651 #endif /* AUTO_INC_DEC */
1653 CLEAR_REG_SET (pbi
->new_set
);
1655 /* If this is not the final pass, and this insn is copying the value of
1656 a library call and it's dead, don't scan the insns that perform the
1657 library call, so that the call's arguments are not marked live. */
1658 if (libcall_is_dead
)
1660 /* Record the death of the dest reg. */
1661 mark_set_regs (pbi
, PATTERN (insn
), insn
);
1663 insn
= XEXP (note
, 0);
1664 return PREV_INSN (insn
);
1666 else if (GET_CODE (PATTERN (insn
)) == SET
1667 && SET_DEST (PATTERN (insn
)) == stack_pointer_rtx
1668 && GET_CODE (SET_SRC (PATTERN (insn
))) == PLUS
1669 && XEXP (SET_SRC (PATTERN (insn
)), 0) == stack_pointer_rtx
1670 && GET_CODE (XEXP (SET_SRC (PATTERN (insn
)), 1)) == CONST_INT
)
1672 /* We have an insn to pop a constant amount off the stack.
1673 (Such insns use PLUS regardless of the direction of the stack,
1674 and any insn to adjust the stack by a constant is always a pop
1676 These insns, if not dead stores, have no effect on life, though
1677 they do have an effect on the memory stores we are tracking. */
1678 invalidate_mems_from_set (pbi
, stack_pointer_rtx
);
1679 /* Still, we need to update local_set, lest ifcvt.c:dead_or_predicable
1680 concludes that the stack pointer is not modified. */
1681 mark_set_regs (pbi
, PATTERN (insn
), insn
);
1686 /* Any regs live at the time of a call instruction must not go
1687 in a register clobbered by calls. Find all regs now live and
1688 record this for them. */
1690 if (CALL_P (insn
) && (flags
& PROP_REG_INFO
))
1692 reg_set_iterator rsi
;
1693 EXECUTE_IF_SET_IN_REG_SET (pbi
->reg_live
, 0, i
, rsi
)
1694 REG_N_CALLS_CROSSED (i
)++;
1697 /* Record sets. Do this even for dead instructions, since they
1698 would have killed the values if they hadn't been deleted. */
1699 mark_set_regs (pbi
, PATTERN (insn
), insn
);
1709 if (GET_CODE (PATTERN (insn
)) == COND_EXEC
)
1710 cond
= COND_EXEC_TEST (PATTERN (insn
));
1712 /* Non-constant calls clobber memory, constant calls do not
1713 clobber memory, though they may clobber outgoing arguments
1715 if (! CONST_OR_PURE_CALL_P (insn
))
1717 free_EXPR_LIST_list (&pbi
->mem_set_list
);
1718 pbi
->mem_set_list_len
= 0;
1721 invalidate_mems_from_set (pbi
, stack_pointer_rtx
);
1723 /* There may be extra registers to be clobbered. */
1724 for (note
= CALL_INSN_FUNCTION_USAGE (insn
);
1726 note
= XEXP (note
, 1))
1727 if (GET_CODE (XEXP (note
, 0)) == CLOBBER
)
1728 mark_set_1 (pbi
, CLOBBER
, XEXP (XEXP (note
, 0), 0),
1729 cond
, insn
, pbi
->flags
);
1731 /* Calls change all call-used and global registers; sibcalls do not
1732 clobber anything that must be preserved at end-of-function,
1733 except for return values. */
1735 sibcall_p
= SIBLING_CALL_P (insn
);
1736 live_at_end
= EXIT_BLOCK_PTR
->global_live_at_start
;
1737 for (i
= 0; i
< FIRST_PSEUDO_REGISTER
; i
++)
1738 if (TEST_HARD_REG_BIT (regs_invalidated_by_call
, i
)
1740 && REGNO_REG_SET_P (live_at_end
, i
)
1741 && ! refers_to_regno_p (i
, i
+1,
1742 current_function_return_rtx
,
1745 enum rtx_code code
= global_regs
[i
] ? SET
: CLOBBER
;
1746 /* We do not want REG_UNUSED notes for these registers. */
1747 mark_set_1 (pbi
, code
, regno_reg_rtx
[i
], cond
, insn
,
1748 pbi
->flags
& ~(PROP_DEATH_NOTES
| PROP_REG_INFO
));
1752 /* If an insn doesn't use CC0, it becomes dead since we assume
1753 that every insn clobbers it. So show it dead here;
1754 mark_used_regs will set it live if it is referenced. */
1759 mark_used_regs (pbi
, PATTERN (insn
), NULL_RTX
, insn
);
1760 if ((flags
& PROP_EQUAL_NOTES
)
1761 && ((note
= find_reg_note (insn
, REG_EQUAL
, NULL_RTX
))
1762 || (note
= find_reg_note (insn
, REG_EQUIV
, NULL_RTX
))))
1763 mark_used_regs (pbi
, XEXP (note
, 0), NULL_RTX
, insn
);
1765 /* Sometimes we may have inserted something before INSN (such as a move)
1766 when we make an auto-inc. So ensure we will scan those insns. */
1768 prev
= PREV_INSN (insn
);
1771 if (! insn_is_dead
&& CALL_P (insn
))
1777 if (GET_CODE (PATTERN (insn
)) == COND_EXEC
)
1778 cond
= COND_EXEC_TEST (PATTERN (insn
));
1780 /* Calls use their arguments, and may clobber memory which
1781 address involves some register. */
1782 for (note
= CALL_INSN_FUNCTION_USAGE (insn
);
1784 note
= XEXP (note
, 1))
1785 /* We find USE or CLOBBER entities in a FUNCTION_USAGE list: both
1786 of which mark_used_regs knows how to handle. */
1787 mark_used_regs (pbi
, XEXP (XEXP (note
, 0), 0), cond
, insn
);
1789 /* The stack ptr is used (honorarily) by a CALL insn. */
1790 if ((flags
& PROP_REG_INFO
)
1791 && !REGNO_REG_SET_P (pbi
->reg_live
, STACK_POINTER_REGNUM
))
1792 reg_deaths
[STACK_POINTER_REGNUM
] = pbi
->insn_num
;
1793 SET_REGNO_REG_SET (pbi
->reg_live
, STACK_POINTER_REGNUM
);
1795 /* Calls may also reference any of the global registers,
1796 so they are made live. */
1797 for (i
= 0; i
< FIRST_PSEUDO_REGISTER
; i
++)
1799 mark_used_reg (pbi
, regno_reg_rtx
[i
], cond
, insn
);
1808 /* Initialize a propagate_block_info struct for public consumption.
1809 Note that the structure itself is opaque to this file, but that
1810 the user can use the regsets provided here. */
1812 struct propagate_block_info
*
1813 init_propagate_block_info (basic_block bb
, regset live
, regset local_set
,
1814 regset cond_local_set
, int flags
)
1816 struct propagate_block_info
*pbi
= xmalloc (sizeof (*pbi
));
1819 pbi
->reg_live
= live
;
1820 pbi
->mem_set_list
= NULL_RTX
;
1821 pbi
->mem_set_list_len
= 0;
1822 pbi
->local_set
= local_set
;
1823 pbi
->cond_local_set
= cond_local_set
;
1828 if (flags
& (PROP_LOG_LINKS
| PROP_AUTOINC
))
1829 pbi
->reg_next_use
= xcalloc (max_reg_num (), sizeof (rtx
));
1831 pbi
->reg_next_use
= NULL
;
1833 pbi
->new_set
= BITMAP_XMALLOC ();
1835 #ifdef HAVE_conditional_execution
1836 pbi
->reg_cond_dead
= splay_tree_new (splay_tree_compare_ints
, NULL
,
1837 free_reg_cond_life_info
);
1838 pbi
->reg_cond_reg
= BITMAP_XMALLOC ();
1840 /* If this block ends in a conditional branch, for each register
1841 live from one side of the branch and not the other, record the
1842 register as conditionally dead. */
1843 if (JUMP_P (BB_END (bb
))
1844 && any_condjump_p (BB_END (bb
)))
1846 regset diff
= OBSTACK_ALLOC_REG_SET (®_obstack
);
1847 basic_block bb_true
, bb_false
;
1850 /* Identify the successor blocks. */
1851 bb_true
= EDGE_SUCC (bb
, 0)->dest
;
1852 if (EDGE_COUNT (bb
->succs
) > 1)
1854 bb_false
= EDGE_SUCC (bb
, 1)->dest
;
1856 if (EDGE_SUCC (bb
, 0)->flags
& EDGE_FALLTHRU
)
1858 basic_block t
= bb_false
;
1863 gcc_assert (EDGE_SUCC (bb
, 1)->flags
& EDGE_FALLTHRU
);
1867 /* This can happen with a conditional jump to the next insn. */
1868 gcc_assert (JUMP_LABEL (BB_END (bb
)) == BB_HEAD (bb_true
));
1870 /* Simplest way to do nothing. */
1874 /* Compute which register lead different lives in the successors. */
1875 bitmap_xor (diff
, bb_true
->global_live_at_start
,
1876 bb_false
->global_live_at_start
);
1878 if (!bitmap_empty_p (diff
))
1880 /* Extract the condition from the branch. */
1881 rtx set_src
= SET_SRC (pc_set (BB_END (bb
)));
1882 rtx cond_true
= XEXP (set_src
, 0);
1883 rtx reg
= XEXP (cond_true
, 0);
1884 enum rtx_code inv_cond
;
1886 if (GET_CODE (reg
) == SUBREG
)
1887 reg
= SUBREG_REG (reg
);
1889 /* We can only track conditional lifetimes if the condition is
1890 in the form of a reversible comparison of a register against
1891 zero. If the condition is more complex than that, then it is
1892 safe not to record any information. */
1893 inv_cond
= reversed_comparison_code (cond_true
, BB_END (bb
));
1894 if (inv_cond
!= UNKNOWN
1896 && XEXP (cond_true
, 1) == const0_rtx
)
1899 = gen_rtx_fmt_ee (inv_cond
,
1900 GET_MODE (cond_true
), XEXP (cond_true
, 0),
1901 XEXP (cond_true
, 1));
1902 reg_set_iterator rsi
;
1904 if (GET_CODE (XEXP (set_src
, 1)) == PC
)
1907 cond_false
= cond_true
;
1911 SET_REGNO_REG_SET (pbi
->reg_cond_reg
, REGNO (reg
));
1913 /* For each such register, mark it conditionally dead. */
1914 EXECUTE_IF_SET_IN_REG_SET (diff
, 0, i
, rsi
)
1916 struct reg_cond_life_info
*rcli
;
1919 rcli
= xmalloc (sizeof (*rcli
));
1921 if (REGNO_REG_SET_P (bb_true
->global_live_at_start
, i
))
1925 rcli
->condition
= cond
;
1926 rcli
->stores
= const0_rtx
;
1927 rcli
->orig_condition
= cond
;
1929 splay_tree_insert (pbi
->reg_cond_dead
, i
,
1930 (splay_tree_value
) rcli
);
1935 FREE_REG_SET (diff
);
1939 /* If this block has no successors, any stores to the frame that aren't
1940 used later in the block are dead. So make a pass over the block
1941 recording any such that are made and show them dead at the end. We do
1942 a very conservative and simple job here. */
1944 && ! (TREE_CODE (TREE_TYPE (current_function_decl
)) == FUNCTION_TYPE
1945 && (TYPE_RETURNS_STACK_DEPRESSED
1946 (TREE_TYPE (current_function_decl
))))
1947 && (flags
& PROP_SCAN_DEAD_STORES
)
1948 && (EDGE_COUNT (bb
->succs
) == 0
1949 || (EDGE_COUNT (bb
->succs
) == 1
1950 && EDGE_SUCC (bb
, 0)->dest
== EXIT_BLOCK_PTR
1951 && ! current_function_calls_eh_return
)))
1954 for (insn
= BB_END (bb
); insn
!= BB_HEAD (bb
); insn
= PREV_INSN (insn
))
1955 if (NONJUMP_INSN_P (insn
)
1956 && (set
= single_set (insn
))
1957 && MEM_P (SET_DEST (set
)))
1959 rtx mem
= SET_DEST (set
);
1960 rtx canon_mem
= canon_rtx (mem
);
1962 if (XEXP (canon_mem
, 0) == frame_pointer_rtx
1963 || (GET_CODE (XEXP (canon_mem
, 0)) == PLUS
1964 && XEXP (XEXP (canon_mem
, 0), 0) == frame_pointer_rtx
1965 && GET_CODE (XEXP (XEXP (canon_mem
, 0), 1)) == CONST_INT
))
1966 add_to_mem_set_list (pbi
, canon_mem
);
1973 /* Release a propagate_block_info struct. */
1976 free_propagate_block_info (struct propagate_block_info
*pbi
)
1978 free_EXPR_LIST_list (&pbi
->mem_set_list
);
1980 BITMAP_XFREE (pbi
->new_set
);
1982 #ifdef HAVE_conditional_execution
1983 splay_tree_delete (pbi
->reg_cond_dead
);
1984 BITMAP_XFREE (pbi
->reg_cond_reg
);
1987 if (pbi
->flags
& PROP_REG_INFO
)
1989 int num
= pbi
->insn_num
;
1991 reg_set_iterator rsi
;
1993 EXECUTE_IF_SET_IN_REG_SET (pbi
->reg_live
, 0, i
, rsi
)
1995 REG_LIVE_LENGTH (i
) += num
- reg_deaths
[i
];
1999 if (pbi
->reg_next_use
)
2000 free (pbi
->reg_next_use
);
2005 /* Compute the registers live at the beginning of a basic block BB from
2006 those live at the end.
2008 When called, REG_LIVE contains those live at the end. On return, it
2009 contains those live at the beginning.
2011 LOCAL_SET, if non-null, will be set with all registers killed
2012 unconditionally by this basic block.
2013 Likewise, COND_LOCAL_SET, if non-null, will be set with all registers
2014 killed conditionally by this basic block. If there is any unconditional
2015 set of a register, then the corresponding bit will be set in LOCAL_SET
2016 and cleared in COND_LOCAL_SET.
2017 It is valid for LOCAL_SET and COND_LOCAL_SET to be the same set. In this
2018 case, the resulting set will be equal to the union of the two sets that
2019 would otherwise be computed.
2021 Return nonzero if an INSN is deleted (i.e. by dead code removal). */
2024 propagate_block (basic_block bb
, regset live
, regset local_set
,
2025 regset cond_local_set
, int flags
)
2027 struct propagate_block_info
*pbi
;
2031 pbi
= init_propagate_block_info (bb
, live
, local_set
, cond_local_set
, flags
);
2033 if (flags
& PROP_REG_INFO
)
2036 reg_set_iterator rsi
;
2038 /* Process the regs live at the end of the block.
2039 Mark them as not local to any one basic block. */
2040 EXECUTE_IF_SET_IN_REG_SET (live
, 0, i
, rsi
)
2041 REG_BASIC_BLOCK (i
) = REG_BLOCK_GLOBAL
;
2044 /* Scan the block an insn at a time from end to beginning. */
2047 for (insn
= BB_END (bb
); ; insn
= prev
)
2049 /* If this is a call to `setjmp' et al, warn if any
2050 non-volatile datum is live. */
2051 if ((flags
& PROP_REG_INFO
)
2053 && find_reg_note (insn
, REG_SETJMP
, NULL
))
2054 IOR_REG_SET (regs_live_at_setjmp
, pbi
->reg_live
);
2056 prev
= propagate_one_insn (pbi
, insn
);
2058 changed
|= insn
!= get_insns ();
2060 changed
|= NEXT_INSN (prev
) != insn
;
2062 if (insn
== BB_HEAD (bb
))
2066 free_propagate_block_info (pbi
);
2071 /* Return 1 if X (the body of an insn, or part of it) is just dead stores
2072 (SET expressions whose destinations are registers dead after the insn).
2073 NEEDED is the regset that says which regs are alive after the insn.
2075 Unless CALL_OK is nonzero, an insn is needed if it contains a CALL.
2077 If X is the entire body of an insn, NOTES contains the reg notes
2078 pertaining to the insn. */
2081 insn_dead_p (struct propagate_block_info
*pbi
, rtx x
, int call_ok
,
2082 rtx notes ATTRIBUTE_UNUSED
)
2084 enum rtx_code code
= GET_CODE (x
);
2086 /* Don't eliminate insns that may trap. */
2087 if (flag_non_call_exceptions
&& may_trap_p (x
))
2091 /* As flow is invoked after combine, we must take existing AUTO_INC
2092 expressions into account. */
2093 for (; notes
; notes
= XEXP (notes
, 1))
2095 if (REG_NOTE_KIND (notes
) == REG_INC
)
2097 int regno
= REGNO (XEXP (notes
, 0));
2099 /* Don't delete insns to set global regs. */
2100 if ((regno
< FIRST_PSEUDO_REGISTER
&& global_regs
[regno
])
2101 || REGNO_REG_SET_P (pbi
->reg_live
, regno
))
2107 /* If setting something that's a reg or part of one,
2108 see if that register's altered value will be live. */
2112 rtx r
= SET_DEST (x
);
2115 if (GET_CODE (r
) == CC0
)
2116 return ! pbi
->cc0_live
;
2119 /* A SET that is a subroutine call cannot be dead. */
2120 if (GET_CODE (SET_SRC (x
)) == CALL
)
2126 /* Don't eliminate loads from volatile memory or volatile asms. */
2127 else if (volatile_refs_p (SET_SRC (x
)))
2134 if (MEM_VOLATILE_P (r
) || GET_MODE (r
) == BLKmode
)
2137 canon_r
= canon_rtx (r
);
2139 /* Walk the set of memory locations we are currently tracking
2140 and see if one is an identical match to this memory location.
2141 If so, this memory write is dead (remember, we're walking
2142 backwards from the end of the block to the start). Since
2143 rtx_equal_p does not check the alias set or flags, we also
2144 must have the potential for them to conflict (anti_dependence). */
2145 for (temp
= pbi
->mem_set_list
; temp
!= 0; temp
= XEXP (temp
, 1))
2146 if (anti_dependence (r
, XEXP (temp
, 0)))
2148 rtx mem
= XEXP (temp
, 0);
2150 if (rtx_equal_p (XEXP (canon_r
, 0), XEXP (mem
, 0))
2151 && (GET_MODE_SIZE (GET_MODE (canon_r
))
2152 <= GET_MODE_SIZE (GET_MODE (mem
))))
2156 /* Check if memory reference matches an auto increment. Only
2157 post increment/decrement or modify are valid. */
2158 if (GET_MODE (mem
) == GET_MODE (r
)
2159 && (GET_CODE (XEXP (mem
, 0)) == POST_DEC
2160 || GET_CODE (XEXP (mem
, 0)) == POST_INC
2161 || GET_CODE (XEXP (mem
, 0)) == POST_MODIFY
)
2162 && GET_MODE (XEXP (mem
, 0)) == GET_MODE (r
)
2163 && rtx_equal_p (XEXP (XEXP (mem
, 0), 0), XEXP (r
, 0)))
2170 while (GET_CODE (r
) == SUBREG
2171 || GET_CODE (r
) == STRICT_LOW_PART
2172 || GET_CODE (r
) == ZERO_EXTRACT
)
2177 int regno
= REGNO (r
);
2180 if (REGNO_REG_SET_P (pbi
->reg_live
, regno
))
2183 /* If this is a hard register, verify that subsequent
2184 words are not needed. */
2185 if (regno
< FIRST_PSEUDO_REGISTER
)
2187 int n
= hard_regno_nregs
[regno
][GET_MODE (r
)];
2190 if (REGNO_REG_SET_P (pbi
->reg_live
, regno
+n
))
2194 /* Don't delete insns to set global regs. */
2195 if (regno
< FIRST_PSEUDO_REGISTER
&& global_regs
[regno
])
2198 /* Make sure insns to set the stack pointer aren't deleted. */
2199 if (regno
== STACK_POINTER_REGNUM
)
2202 /* ??? These bits might be redundant with the force live bits
2203 in calculate_global_regs_live. We would delete from
2204 sequential sets; whether this actually affects real code
2205 for anything but the stack pointer I don't know. */
2206 /* Make sure insns to set the frame pointer aren't deleted. */
2207 if (regno
== FRAME_POINTER_REGNUM
2208 && (! reload_completed
|| frame_pointer_needed
))
2210 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
2211 if (regno
== HARD_FRAME_POINTER_REGNUM
2212 && (! reload_completed
|| frame_pointer_needed
))
2216 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
2217 /* Make sure insns to set arg pointer are never deleted
2218 (if the arg pointer isn't fixed, there will be a USE
2219 for it, so we can treat it normally). */
2220 if (regno
== ARG_POINTER_REGNUM
&& fixed_regs
[regno
])
2224 /* Otherwise, the set is dead. */
2230 /* If performing several activities, insn is dead if each activity
2231 is individually dead. Also, CLOBBERs and USEs can be ignored; a
2232 CLOBBER or USE that's inside a PARALLEL doesn't make the insn
2234 else if (code
== PARALLEL
)
2236 int i
= XVECLEN (x
, 0);
2238 for (i
--; i
>= 0; i
--)
2239 if (GET_CODE (XVECEXP (x
, 0, i
)) != CLOBBER
2240 && GET_CODE (XVECEXP (x
, 0, i
)) != USE
2241 && ! insn_dead_p (pbi
, XVECEXP (x
, 0, i
), call_ok
, NULL_RTX
))
2247 /* A CLOBBER of a pseudo-register that is dead serves no purpose. That
2248 is not necessarily true for hard registers until after reload. */
2249 else if (code
== CLOBBER
)
2251 if (REG_P (XEXP (x
, 0))
2252 && (REGNO (XEXP (x
, 0)) >= FIRST_PSEUDO_REGISTER
2253 || reload_completed
)
2254 && ! REGNO_REG_SET_P (pbi
->reg_live
, REGNO (XEXP (x
, 0))))
2258 /* ??? A base USE is a historical relic. It ought not be needed anymore.
2259 Instances where it is still used are either (1) temporary and the USE
2260 escaped the pass, (2) cruft and the USE need not be emitted anymore,
2261 or (3) hiding bugs elsewhere that are not properly representing data
2267 /* If INSN is the last insn in a libcall, and assuming INSN is dead,
2268 return 1 if the entire library call is dead.
2269 This is true if INSN copies a register (hard or pseudo)
2270 and if the hard return reg of the call insn is dead.
2271 (The caller should have tested the destination of the SET inside
2272 INSN already for death.)
2274 If this insn doesn't just copy a register, then we don't
2275 have an ordinary libcall. In that case, cse could not have
2276 managed to substitute the source for the dest later on,
2277 so we can assume the libcall is dead.
2279 PBI is the block info giving pseudoregs live before this insn.
2280 NOTE is the REG_RETVAL note of the insn. */
2283 libcall_dead_p (struct propagate_block_info
*pbi
, rtx note
, rtx insn
)
2285 rtx x
= single_set (insn
);
2289 rtx r
= SET_SRC (x
);
2293 rtx call
= XEXP (note
, 0);
2297 /* Find the call insn. */
2298 while (call
!= insn
&& !CALL_P (call
))
2299 call
= NEXT_INSN (call
);
2301 /* If there is none, do nothing special,
2302 since ordinary death handling can understand these insns. */
2306 /* See if the hard reg holding the value is dead.
2307 If this is a PARALLEL, find the call within it. */
2308 call_pat
= PATTERN (call
);
2309 if (GET_CODE (call_pat
) == PARALLEL
)
2311 for (i
= XVECLEN (call_pat
, 0) - 1; i
>= 0; i
--)
2312 if (GET_CODE (XVECEXP (call_pat
, 0, i
)) == SET
2313 && GET_CODE (SET_SRC (XVECEXP (call_pat
, 0, i
))) == CALL
)
2316 /* This may be a library call that is returning a value
2317 via invisible pointer. Do nothing special, since
2318 ordinary death handling can understand these insns. */
2322 call_pat
= XVECEXP (call_pat
, 0, i
);
2325 return insn_dead_p (pbi
, call_pat
, 1, REG_NOTES (call
));
2331 /* 1 if register REGNO was alive at a place where `setjmp' was called
2332 and was set more than once or is an argument.
2333 Such regs may be clobbered by `longjmp'. */
2336 regno_clobbered_at_setjmp (int regno
)
2338 if (n_basic_blocks
== 0)
2341 return ((REG_N_SETS (regno
) > 1
2342 || REGNO_REG_SET_P (ENTRY_BLOCK_PTR
->global_live_at_end
, regno
))
2343 && REGNO_REG_SET_P (regs_live_at_setjmp
, regno
));
2346 /* Add MEM to PBI->MEM_SET_LIST. MEM should be canonical. Respect the
2347 maximal list size; look for overlaps in mode and select the largest. */
2349 add_to_mem_set_list (struct propagate_block_info
*pbi
, rtx mem
)
2353 /* We don't know how large a BLKmode store is, so we must not
2354 take them into consideration. */
2355 if (GET_MODE (mem
) == BLKmode
)
2358 for (i
= pbi
->mem_set_list
; i
; i
= XEXP (i
, 1))
2360 rtx e
= XEXP (i
, 0);
2361 if (rtx_equal_p (XEXP (mem
, 0), XEXP (e
, 0)))
2363 if (GET_MODE_SIZE (GET_MODE (mem
)) > GET_MODE_SIZE (GET_MODE (e
)))
2366 /* If we must store a copy of the mem, we can just modify
2367 the mode of the stored copy. */
2368 if (pbi
->flags
& PROP_AUTOINC
)
2369 PUT_MODE (e
, GET_MODE (mem
));
2378 if (pbi
->mem_set_list_len
< MAX_MEM_SET_LIST_LEN
)
2381 /* Store a copy of mem, otherwise the address may be
2382 scrogged by find_auto_inc. */
2383 if (pbi
->flags
& PROP_AUTOINC
)
2384 mem
= shallow_copy_rtx (mem
);
2386 pbi
->mem_set_list
= alloc_EXPR_LIST (0, mem
, pbi
->mem_set_list
);
2387 pbi
->mem_set_list_len
++;
2391 /* INSN references memory, possibly using autoincrement addressing modes.
2392 Find any entries on the mem_set_list that need to be invalidated due
2393 to an address change. */
2396 invalidate_mems_from_autoinc (rtx
*px
, void *data
)
2399 struct propagate_block_info
*pbi
= data
;
2401 if (GET_RTX_CLASS (GET_CODE (x
)) == RTX_AUTOINC
)
2403 invalidate_mems_from_set (pbi
, XEXP (x
, 0));
2410 /* EXP is a REG. Remove any dependent entries from pbi->mem_set_list. */
2413 invalidate_mems_from_set (struct propagate_block_info
*pbi
, rtx exp
)
2415 rtx temp
= pbi
->mem_set_list
;
2416 rtx prev
= NULL_RTX
;
2421 next
= XEXP (temp
, 1);
2422 if (reg_overlap_mentioned_p (exp
, XEXP (temp
, 0)))
2424 /* Splice this entry out of the list. */
2426 XEXP (prev
, 1) = next
;
2428 pbi
->mem_set_list
= next
;
2429 free_EXPR_LIST_node (temp
);
2430 pbi
->mem_set_list_len
--;
2438 /* Process the registers that are set within X. Their bits are set to
2439 1 in the regset DEAD, because they are dead prior to this insn.
2441 If INSN is nonzero, it is the insn being processed.
2443 FLAGS is the set of operations to perform. */
2446 mark_set_regs (struct propagate_block_info
*pbi
, rtx x
, rtx insn
)
2448 rtx cond
= NULL_RTX
;
2451 int flags
= pbi
->flags
;
2454 for (link
= REG_NOTES (insn
); link
; link
= XEXP (link
, 1))
2456 if (REG_NOTE_KIND (link
) == REG_INC
)
2457 mark_set_1 (pbi
, SET
, XEXP (link
, 0),
2458 (GET_CODE (x
) == COND_EXEC
2459 ? COND_EXEC_TEST (x
) : NULL_RTX
),
2463 switch (code
= GET_CODE (x
))
2466 if (GET_CODE (XEXP (x
, 1)) == ASM_OPERANDS
)
2467 flags
|= PROP_ASM_SCAN
;
2470 mark_set_1 (pbi
, code
, SET_DEST (x
), cond
, insn
, flags
);
2474 cond
= COND_EXEC_TEST (x
);
2475 x
= COND_EXEC_CODE (x
);
2482 /* We must scan forwards. If we have an asm, we need to set
2483 the PROP_ASM_SCAN flag before scanning the clobbers. */
2484 for (i
= 0; i
< XVECLEN (x
, 0); i
++)
2486 rtx sub
= XVECEXP (x
, 0, i
);
2487 switch (code
= GET_CODE (sub
))
2492 cond
= COND_EXEC_TEST (sub
);
2493 sub
= COND_EXEC_CODE (sub
);
2494 if (GET_CODE (sub
) == SET
)
2496 if (GET_CODE (sub
) == CLOBBER
)
2502 if (GET_CODE (XEXP (sub
, 1)) == ASM_OPERANDS
)
2503 flags
|= PROP_ASM_SCAN
;
2507 mark_set_1 (pbi
, code
, SET_DEST (sub
), cond
, insn
, flags
);
2511 flags
|= PROP_ASM_SCAN
;
2526 /* Process a single set, which appears in INSN. REG (which may not
2527 actually be a REG, it may also be a SUBREG, PARALLEL, etc.) is
2528 being set using the CODE (which may be SET, CLOBBER, or COND_EXEC).
2529 If the set is conditional (because it appear in a COND_EXEC), COND
2530 will be the condition. */
2533 mark_set_1 (struct propagate_block_info
*pbi
, enum rtx_code code
, rtx reg
, rtx cond
, rtx insn
, int flags
)
2535 int regno_first
= -1, regno_last
= -1;
2536 unsigned long not_dead
= 0;
2539 /* Modifying just one hardware register of a multi-reg value or just a
2540 byte field of a register does not mean the value from before this insn
2541 is now dead. Of course, if it was dead after it's unused now. */
2543 switch (GET_CODE (reg
))
2546 /* Some targets place small structures in registers for return values of
2547 functions. We have to detect this case specially here to get correct
2548 flow information. */
2549 for (i
= XVECLEN (reg
, 0) - 1; i
>= 0; i
--)
2550 if (XEXP (XVECEXP (reg
, 0, i
), 0) != 0)
2551 mark_set_1 (pbi
, code
, XEXP (XVECEXP (reg
, 0, i
), 0), cond
, insn
,
2557 case STRICT_LOW_PART
:
2558 /* ??? Assumes STRICT_LOW_PART not used on multi-word registers. */
2560 reg
= XEXP (reg
, 0);
2561 while (GET_CODE (reg
) == SUBREG
2562 || GET_CODE (reg
) == ZERO_EXTRACT
2563 || GET_CODE (reg
) == SIGN_EXTRACT
2564 || GET_CODE (reg
) == STRICT_LOW_PART
);
2567 not_dead
= (unsigned long) REGNO_REG_SET_P (pbi
->reg_live
, REGNO (reg
));
2571 regno_last
= regno_first
= REGNO (reg
);
2572 if (regno_first
< FIRST_PSEUDO_REGISTER
)
2573 regno_last
+= hard_regno_nregs
[regno_first
][GET_MODE (reg
)] - 1;
2577 if (REG_P (SUBREG_REG (reg
)))
2579 enum machine_mode outer_mode
= GET_MODE (reg
);
2580 enum machine_mode inner_mode
= GET_MODE (SUBREG_REG (reg
));
2582 /* Identify the range of registers affected. This is moderately
2583 tricky for hard registers. See alter_subreg. */
2585 regno_last
= regno_first
= REGNO (SUBREG_REG (reg
));
2586 if (regno_first
< FIRST_PSEUDO_REGISTER
)
2588 regno_first
+= subreg_regno_offset (regno_first
, inner_mode
,
2591 regno_last
= (regno_first
2592 + hard_regno_nregs
[regno_first
][outer_mode
] - 1);
2594 /* Since we've just adjusted the register number ranges, make
2595 sure REG matches. Otherwise some_was_live will be clear
2596 when it shouldn't have been, and we'll create incorrect
2597 REG_UNUSED notes. */
2598 reg
= gen_rtx_REG (outer_mode
, regno_first
);
2602 /* If the number of words in the subreg is less than the number
2603 of words in the full register, we have a well-defined partial
2604 set. Otherwise the high bits are undefined.
2606 This is only really applicable to pseudos, since we just took
2607 care of multi-word hard registers. */
2608 if (((GET_MODE_SIZE (outer_mode
)
2609 + UNITS_PER_WORD
- 1) / UNITS_PER_WORD
)
2610 < ((GET_MODE_SIZE (inner_mode
)
2611 + UNITS_PER_WORD
- 1) / UNITS_PER_WORD
))
2612 not_dead
= (unsigned long) REGNO_REG_SET_P (pbi
->reg_live
,
2615 reg
= SUBREG_REG (reg
);
2619 reg
= SUBREG_REG (reg
);
2626 /* If this set is a MEM, then it kills any aliased writes.
2627 If this set is a REG, then it kills any MEMs which use the reg. */
2628 if (optimize
&& (flags
& PROP_SCAN_DEAD_STORES
))
2631 invalidate_mems_from_set (pbi
, reg
);
2633 /* If the memory reference had embedded side effects (autoincrement
2634 address modes) then we may need to kill some entries on the
2636 if (insn
&& MEM_P (reg
))
2637 for_each_rtx (&PATTERN (insn
), invalidate_mems_from_autoinc
, pbi
);
2639 if (MEM_P (reg
) && ! side_effects_p (reg
)
2640 /* ??? With more effort we could track conditional memory life. */
2642 add_to_mem_set_list (pbi
, canon_rtx (reg
));
2646 && ! (regno_first
== FRAME_POINTER_REGNUM
2647 && (! reload_completed
|| frame_pointer_needed
))
2648 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
2649 && ! (regno_first
== HARD_FRAME_POINTER_REGNUM
2650 && (! reload_completed
|| frame_pointer_needed
))
2652 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
2653 && ! (regno_first
== ARG_POINTER_REGNUM
&& fixed_regs
[regno_first
])
2657 int some_was_live
= 0, some_was_dead
= 0;
2659 for (i
= regno_first
; i
<= regno_last
; ++i
)
2661 int needed_regno
= REGNO_REG_SET_P (pbi
->reg_live
, i
);
2664 /* Order of the set operation matters here since both
2665 sets may be the same. */
2666 CLEAR_REGNO_REG_SET (pbi
->cond_local_set
, i
);
2667 if (cond
!= NULL_RTX
2668 && ! REGNO_REG_SET_P (pbi
->local_set
, i
))
2669 SET_REGNO_REG_SET (pbi
->cond_local_set
, i
);
2671 SET_REGNO_REG_SET (pbi
->local_set
, i
);
2673 if (code
!= CLOBBER
)
2674 SET_REGNO_REG_SET (pbi
->new_set
, i
);
2676 some_was_live
|= needed_regno
;
2677 some_was_dead
|= ! needed_regno
;
2680 #ifdef HAVE_conditional_execution
2681 /* Consider conditional death in deciding that the register needs
2683 if (some_was_live
&& ! not_dead
2684 /* The stack pointer is never dead. Well, not strictly true,
2685 but it's very difficult to tell from here. Hopefully
2686 combine_stack_adjustments will fix up the most egregious
2688 && regno_first
!= STACK_POINTER_REGNUM
)
2690 for (i
= regno_first
; i
<= regno_last
; ++i
)
2691 if (! mark_regno_cond_dead (pbi
, i
, cond
))
2692 not_dead
|= ((unsigned long) 1) << (i
- regno_first
);
2696 /* Additional data to record if this is the final pass. */
2697 if (flags
& (PROP_LOG_LINKS
| PROP_REG_INFO
2698 | PROP_DEATH_NOTES
| PROP_AUTOINC
))
2701 int blocknum
= pbi
->bb
->index
;
2704 if (flags
& (PROP_LOG_LINKS
| PROP_AUTOINC
))
2706 y
= pbi
->reg_next_use
[regno_first
];
2708 /* The next use is no longer next, since a store intervenes. */
2709 for (i
= regno_first
; i
<= regno_last
; ++i
)
2710 pbi
->reg_next_use
[i
] = 0;
2713 if (flags
& PROP_REG_INFO
)
2715 for (i
= regno_first
; i
<= regno_last
; ++i
)
2717 /* Count (weighted) references, stores, etc. This counts a
2718 register twice if it is modified, but that is correct. */
2719 REG_N_SETS (i
) += 1;
2720 REG_N_REFS (i
) += 1;
2721 REG_FREQ (i
) += REG_FREQ_FROM_BB (pbi
->bb
);
2723 /* The insns where a reg is live are normally counted
2724 elsewhere, but we want the count to include the insn
2725 where the reg is set, and the normal counting mechanism
2726 would not count it. */
2727 REG_LIVE_LENGTH (i
) += 1;
2730 /* If this is a hard reg, record this function uses the reg. */
2731 if (regno_first
< FIRST_PSEUDO_REGISTER
)
2733 for (i
= regno_first
; i
<= regno_last
; i
++)
2734 regs_ever_live
[i
] = 1;
2735 if (flags
& PROP_ASM_SCAN
)
2736 for (i
= regno_first
; i
<= regno_last
; i
++)
2737 regs_asm_clobbered
[i
] = 1;
2741 /* Keep track of which basic blocks each reg appears in. */
2742 if (REG_BASIC_BLOCK (regno_first
) == REG_BLOCK_UNKNOWN
)
2743 REG_BASIC_BLOCK (regno_first
) = blocknum
;
2744 else if (REG_BASIC_BLOCK (regno_first
) != blocknum
)
2745 REG_BASIC_BLOCK (regno_first
) = REG_BLOCK_GLOBAL
;
2749 if (! some_was_dead
)
2751 if (flags
& PROP_LOG_LINKS
)
2753 /* Make a logical link from the next following insn
2754 that uses this register, back to this insn.
2755 The following insns have already been processed.
2757 We don't build a LOG_LINK for hard registers containing
2758 in ASM_OPERANDs. If these registers get replaced,
2759 we might wind up changing the semantics of the insn,
2760 even if reload can make what appear to be valid
2763 We don't build a LOG_LINK for global registers to
2764 or from a function call. We don't want to let
2765 combine think that it knows what is going on with
2766 global registers. */
2767 if (y
&& (BLOCK_NUM (y
) == blocknum
)
2768 && (regno_first
>= FIRST_PSEUDO_REGISTER
2769 || (asm_noperands (PATTERN (y
)) < 0
2770 && ! ((CALL_P (insn
)
2772 && global_regs
[regno_first
]))))
2773 LOG_LINKS (y
) = alloc_INSN_LIST (insn
, LOG_LINKS (y
));
2778 else if (! some_was_live
)
2780 if (flags
& PROP_REG_INFO
)
2781 REG_N_DEATHS (regno_first
) += 1;
2783 if (flags
& PROP_DEATH_NOTES
)
2785 /* Note that dead stores have already been deleted
2786 when possible. If we get here, we have found a
2787 dead store that cannot be eliminated (because the
2788 same insn does something useful). Indicate this
2789 by marking the reg being set as dying here. */
2791 = alloc_EXPR_LIST (REG_UNUSED
, reg
, REG_NOTES (insn
));
2796 if (flags
& PROP_DEATH_NOTES
)
2798 /* This is a case where we have a multi-word hard register
2799 and some, but not all, of the words of the register are
2800 needed in subsequent insns. Write REG_UNUSED notes
2801 for those parts that were not needed. This case should
2804 for (i
= regno_first
; i
<= regno_last
; ++i
)
2805 if (! REGNO_REG_SET_P (pbi
->reg_live
, i
))
2807 = alloc_EXPR_LIST (REG_UNUSED
,
2814 /* Mark the register as being dead. */
2816 /* The stack pointer is never dead. Well, not strictly true,
2817 but it's very difficult to tell from here. Hopefully
2818 combine_stack_adjustments will fix up the most egregious
2820 && regno_first
!= STACK_POINTER_REGNUM
)
2822 for (i
= regno_first
; i
<= regno_last
; ++i
)
2823 if (!(not_dead
& (((unsigned long) 1) << (i
- regno_first
))))
2825 if ((pbi
->flags
& PROP_REG_INFO
)
2826 && REGNO_REG_SET_P (pbi
->reg_live
, i
))
2828 REG_LIVE_LENGTH (i
) += pbi
->insn_num
- reg_deaths
[i
];
2831 CLEAR_REGNO_REG_SET (pbi
->reg_live
, i
);
2835 else if (REG_P (reg
))
2837 if (flags
& (PROP_LOG_LINKS
| PROP_AUTOINC
))
2838 pbi
->reg_next_use
[regno_first
] = 0;
2840 if ((flags
& PROP_REG_INFO
) != 0
2841 && (flags
& PROP_ASM_SCAN
) != 0
2842 && regno_first
< FIRST_PSEUDO_REGISTER
)
2844 for (i
= regno_first
; i
<= regno_last
; i
++)
2845 regs_asm_clobbered
[i
] = 1;
2849 /* If this is the last pass and this is a SCRATCH, show it will be dying
2850 here and count it. */
2851 else if (GET_CODE (reg
) == SCRATCH
)
2853 if (flags
& PROP_DEATH_NOTES
)
2855 = alloc_EXPR_LIST (REG_UNUSED
, reg
, REG_NOTES (insn
));
2859 #ifdef HAVE_conditional_execution
2860 /* Mark REGNO conditionally dead.
2861 Return true if the register is now unconditionally dead. */
2864 mark_regno_cond_dead (struct propagate_block_info
*pbi
, int regno
, rtx cond
)
2866 /* If this is a store to a predicate register, the value of the
2867 predicate is changing, we don't know that the predicate as seen
2868 before is the same as that seen after. Flush all dependent
2869 conditions from reg_cond_dead. This will make all such
2870 conditionally live registers unconditionally live. */
2871 if (REGNO_REG_SET_P (pbi
->reg_cond_reg
, regno
))
2872 flush_reg_cond_reg (pbi
, regno
);
2874 /* If this is an unconditional store, remove any conditional
2875 life that may have existed. */
2876 if (cond
== NULL_RTX
)
2877 splay_tree_remove (pbi
->reg_cond_dead
, regno
);
2880 splay_tree_node node
;
2881 struct reg_cond_life_info
*rcli
;
2884 /* Otherwise this is a conditional set. Record that fact.
2885 It may have been conditionally used, or there may be a
2886 subsequent set with a complimentary condition. */
2888 node
= splay_tree_lookup (pbi
->reg_cond_dead
, regno
);
2891 /* The register was unconditionally live previously.
2892 Record the current condition as the condition under
2893 which it is dead. */
2894 rcli
= xmalloc (sizeof (*rcli
));
2895 rcli
->condition
= cond
;
2896 rcli
->stores
= cond
;
2897 rcli
->orig_condition
= const0_rtx
;
2898 splay_tree_insert (pbi
->reg_cond_dead
, regno
,
2899 (splay_tree_value
) rcli
);
2901 SET_REGNO_REG_SET (pbi
->reg_cond_reg
, REGNO (XEXP (cond
, 0)));
2903 /* Not unconditionally dead. */
2908 /* The register was conditionally live previously.
2909 Add the new condition to the old. */
2910 rcli
= (struct reg_cond_life_info
*) node
->value
;
2911 ncond
= rcli
->condition
;
2912 ncond
= ior_reg_cond (ncond
, cond
, 1);
2913 if (rcli
->stores
== const0_rtx
)
2914 rcli
->stores
= cond
;
2915 else if (rcli
->stores
!= const1_rtx
)
2916 rcli
->stores
= ior_reg_cond (rcli
->stores
, cond
, 1);
2918 /* If the register is now unconditionally dead, remove the entry
2919 in the splay_tree. A register is unconditionally dead if the
2920 dead condition ncond is true. A register is also unconditionally
2921 dead if the sum of all conditional stores is an unconditional
2922 store (stores is true), and the dead condition is identically the
2923 same as the original dead condition initialized at the end of
2924 the block. This is a pointer compare, not an rtx_equal_p
2926 if (ncond
== const1_rtx
2927 || (ncond
== rcli
->orig_condition
&& rcli
->stores
== const1_rtx
))
2928 splay_tree_remove (pbi
->reg_cond_dead
, regno
);
2931 rcli
->condition
= ncond
;
2933 SET_REGNO_REG_SET (pbi
->reg_cond_reg
, REGNO (XEXP (cond
, 0)));
2935 /* Not unconditionally dead. */
2944 /* Called from splay_tree_delete for pbi->reg_cond_life. */
2947 free_reg_cond_life_info (splay_tree_value value
)
2949 struct reg_cond_life_info
*rcli
= (struct reg_cond_life_info
*) value
;
2953 /* Helper function for flush_reg_cond_reg. */
2956 flush_reg_cond_reg_1 (splay_tree_node node
, void *data
)
2958 struct reg_cond_life_info
*rcli
;
2959 int *xdata
= (int *) data
;
2960 unsigned int regno
= xdata
[0];
2962 /* Don't need to search if last flushed value was farther on in
2963 the in-order traversal. */
2964 if (xdata
[1] >= (int) node
->key
)
2967 /* Splice out portions of the expression that refer to regno. */
2968 rcli
= (struct reg_cond_life_info
*) node
->value
;
2969 rcli
->condition
= elim_reg_cond (rcli
->condition
, regno
);
2970 if (rcli
->stores
!= const0_rtx
&& rcli
->stores
!= const1_rtx
)
2971 rcli
->stores
= elim_reg_cond (rcli
->stores
, regno
);
2973 /* If the entire condition is now false, signal the node to be removed. */
2974 if (rcli
->condition
== const0_rtx
)
2976 xdata
[1] = node
->key
;
2980 gcc_assert (rcli
->condition
!= const1_rtx
);
2985 /* Flush all (sub) expressions referring to REGNO from REG_COND_LIVE. */
2988 flush_reg_cond_reg (struct propagate_block_info
*pbi
, int regno
)
2994 while (splay_tree_foreach (pbi
->reg_cond_dead
,
2995 flush_reg_cond_reg_1
, pair
) == -1)
2996 splay_tree_remove (pbi
->reg_cond_dead
, pair
[1]);
2998 CLEAR_REGNO_REG_SET (pbi
->reg_cond_reg
, regno
);
3001 /* Logical arithmetic on predicate conditions. IOR, NOT and AND.
3002 For ior/and, the ADD flag determines whether we want to add the new
3003 condition X to the old one unconditionally. If it is zero, we will
3004 only return a new expression if X allows us to simplify part of
3005 OLD, otherwise we return NULL to the caller.
3006 If ADD is nonzero, we will return a new condition in all cases. The
3007 toplevel caller of one of these functions should always pass 1 for
3011 ior_reg_cond (rtx old
, rtx x
, int add
)
3015 if (COMPARISON_P (old
))
3017 if (COMPARISON_P (x
)
3018 && REVERSE_CONDEXEC_PREDICATES_P (x
, old
)
3019 && REGNO (XEXP (x
, 0)) == REGNO (XEXP (old
, 0)))
3021 if (GET_CODE (x
) == GET_CODE (old
)
3022 && REGNO (XEXP (x
, 0)) == REGNO (XEXP (old
, 0)))
3026 return gen_rtx_IOR (0, old
, x
);
3029 switch (GET_CODE (old
))
3032 op0
= ior_reg_cond (XEXP (old
, 0), x
, 0);
3033 op1
= ior_reg_cond (XEXP (old
, 1), x
, 0);
3034 if (op0
!= NULL
|| op1
!= NULL
)
3036 if (op0
== const0_rtx
)
3037 return op1
? op1
: gen_rtx_IOR (0, XEXP (old
, 1), x
);
3038 if (op1
== const0_rtx
)
3039 return op0
? op0
: gen_rtx_IOR (0, XEXP (old
, 0), x
);
3040 if (op0
== const1_rtx
|| op1
== const1_rtx
)
3043 op0
= gen_rtx_IOR (0, XEXP (old
, 0), x
);
3044 else if (rtx_equal_p (x
, op0
))
3045 /* (x | A) | x ~ (x | A). */
3048 op1
= gen_rtx_IOR (0, XEXP (old
, 1), x
);
3049 else if (rtx_equal_p (x
, op1
))
3050 /* (A | x) | x ~ (A | x). */
3052 return gen_rtx_IOR (0, op0
, op1
);
3056 return gen_rtx_IOR (0, old
, x
);
3059 op0
= ior_reg_cond (XEXP (old
, 0), x
, 0);
3060 op1
= ior_reg_cond (XEXP (old
, 1), x
, 0);
3061 if (op0
!= NULL
|| op1
!= NULL
)
3063 if (op0
== const1_rtx
)
3064 return op1
? op1
: gen_rtx_IOR (0, XEXP (old
, 1), x
);
3065 if (op1
== const1_rtx
)
3066 return op0
? op0
: gen_rtx_IOR (0, XEXP (old
, 0), x
);
3067 if (op0
== const0_rtx
|| op1
== const0_rtx
)
3070 op0
= gen_rtx_IOR (0, XEXP (old
, 0), x
);
3071 else if (rtx_equal_p (x
, op0
))
3072 /* (x & A) | x ~ x. */
3075 op1
= gen_rtx_IOR (0, XEXP (old
, 1), x
);
3076 else if (rtx_equal_p (x
, op1
))
3077 /* (A & x) | x ~ x. */
3079 return gen_rtx_AND (0, op0
, op1
);
3083 return gen_rtx_IOR (0, old
, x
);
3086 op0
= and_reg_cond (XEXP (old
, 0), not_reg_cond (x
), 0);
3088 return not_reg_cond (op0
);
3091 return gen_rtx_IOR (0, old
, x
);
3099 not_reg_cond (rtx x
)
3101 if (x
== const0_rtx
)
3103 else if (x
== const1_rtx
)
3105 if (GET_CODE (x
) == NOT
)
3107 if (COMPARISON_P (x
)
3108 && REG_P (XEXP (x
, 0)))
3110 gcc_assert (XEXP (x
, 1) == const0_rtx
);
3112 return gen_rtx_fmt_ee (reversed_comparison_code (x
, NULL
),
3113 VOIDmode
, XEXP (x
, 0), const0_rtx
);
3115 return gen_rtx_NOT (0, x
);
3119 and_reg_cond (rtx old
, rtx x
, int add
)
3123 if (COMPARISON_P (old
))
3125 if (COMPARISON_P (x
)
3126 && GET_CODE (x
) == reversed_comparison_code (old
, NULL
)
3127 && REGNO (XEXP (x
, 0)) == REGNO (XEXP (old
, 0)))
3129 if (GET_CODE (x
) == GET_CODE (old
)
3130 && REGNO (XEXP (x
, 0)) == REGNO (XEXP (old
, 0)))
3134 return gen_rtx_AND (0, old
, x
);
3137 switch (GET_CODE (old
))
3140 op0
= and_reg_cond (XEXP (old
, 0), x
, 0);
3141 op1
= and_reg_cond (XEXP (old
, 1), x
, 0);
3142 if (op0
!= NULL
|| op1
!= NULL
)
3144 if (op0
== const0_rtx
)
3145 return op1
? op1
: gen_rtx_AND (0, XEXP (old
, 1), x
);
3146 if (op1
== const0_rtx
)
3147 return op0
? op0
: gen_rtx_AND (0, XEXP (old
, 0), x
);
3148 if (op0
== const1_rtx
|| op1
== const1_rtx
)
3151 op0
= gen_rtx_AND (0, XEXP (old
, 0), x
);
3152 else if (rtx_equal_p (x
, op0
))
3153 /* (x | A) & x ~ x. */
3156 op1
= gen_rtx_AND (0, XEXP (old
, 1), x
);
3157 else if (rtx_equal_p (x
, op1
))
3158 /* (A | x) & x ~ x. */
3160 return gen_rtx_IOR (0, op0
, op1
);
3164 return gen_rtx_AND (0, old
, x
);
3167 op0
= and_reg_cond (XEXP (old
, 0), x
, 0);
3168 op1
= and_reg_cond (XEXP (old
, 1), x
, 0);
3169 if (op0
!= NULL
|| op1
!= NULL
)
3171 if (op0
== const1_rtx
)
3172 return op1
? op1
: gen_rtx_AND (0, XEXP (old
, 1), x
);
3173 if (op1
== const1_rtx
)
3174 return op0
? op0
: gen_rtx_AND (0, XEXP (old
, 0), x
);
3175 if (op0
== const0_rtx
|| op1
== const0_rtx
)
3178 op0
= gen_rtx_AND (0, XEXP (old
, 0), x
);
3179 else if (rtx_equal_p (x
, op0
))
3180 /* (x & A) & x ~ (x & A). */
3183 op1
= gen_rtx_AND (0, XEXP (old
, 1), x
);
3184 else if (rtx_equal_p (x
, op1
))
3185 /* (A & x) & x ~ (A & x). */
3187 return gen_rtx_AND (0, op0
, op1
);
3191 return gen_rtx_AND (0, old
, x
);
3194 op0
= ior_reg_cond (XEXP (old
, 0), not_reg_cond (x
), 0);
3196 return not_reg_cond (op0
);
3199 return gen_rtx_AND (0, old
, x
);
3206 /* Given a condition X, remove references to reg REGNO and return the
3207 new condition. The removal will be done so that all conditions
3208 involving REGNO are considered to evaluate to false. This function
3209 is used when the value of REGNO changes. */
3212 elim_reg_cond (rtx x
, unsigned int regno
)
3216 if (COMPARISON_P (x
))
3218 if (REGNO (XEXP (x
, 0)) == regno
)
3223 switch (GET_CODE (x
))
3226 op0
= elim_reg_cond (XEXP (x
, 0), regno
);
3227 op1
= elim_reg_cond (XEXP (x
, 1), regno
);
3228 if (op0
== const0_rtx
|| op1
== const0_rtx
)
3230 if (op0
== const1_rtx
)
3232 if (op1
== const1_rtx
)
3234 if (op0
== XEXP (x
, 0) && op1
== XEXP (x
, 1))
3236 return gen_rtx_AND (0, op0
, op1
);
3239 op0
= elim_reg_cond (XEXP (x
, 0), regno
);
3240 op1
= elim_reg_cond (XEXP (x
, 1), regno
);
3241 if (op0
== const1_rtx
|| op1
== const1_rtx
)
3243 if (op0
== const0_rtx
)
3245 if (op1
== const0_rtx
)
3247 if (op0
== XEXP (x
, 0) && op1
== XEXP (x
, 1))
3249 return gen_rtx_IOR (0, op0
, op1
);
3252 op0
= elim_reg_cond (XEXP (x
, 0), regno
);
3253 if (op0
== const0_rtx
)
3255 if (op0
== const1_rtx
)
3257 if (op0
!= XEXP (x
, 0))
3258 return not_reg_cond (op0
);
3265 #endif /* HAVE_conditional_execution */
3269 /* Try to substitute the auto-inc expression INC as the address inside
3270 MEM which occurs in INSN. Currently, the address of MEM is an expression
3271 involving INCR_REG, and INCR is the next use of INCR_REG; it is an insn
3272 that has a single set whose source is a PLUS of INCR_REG and something
3276 attempt_auto_inc (struct propagate_block_info
*pbi
, rtx inc
, rtx insn
,
3277 rtx mem
, rtx incr
, rtx incr_reg
)
3279 int regno
= REGNO (incr_reg
);
3280 rtx set
= single_set (incr
);
3281 rtx q
= SET_DEST (set
);
3282 rtx y
= SET_SRC (set
);
3283 int opnum
= XEXP (y
, 0) == incr_reg
? 0 : 1;
3286 /* Make sure this reg appears only once in this insn. */
3287 if (count_occurrences (PATTERN (insn
), incr_reg
, 1) != 1)
3290 if (dead_or_set_p (incr
, incr_reg
)
3291 /* Mustn't autoinc an eliminable register. */
3292 && (regno
>= FIRST_PSEUDO_REGISTER
3293 || ! TEST_HARD_REG_BIT (elim_reg_set
, regno
)))
3295 /* This is the simple case. Try to make the auto-inc. If
3296 we can't, we are done. Otherwise, we will do any
3297 needed updates below. */
3298 if (! validate_change (insn
, &XEXP (mem
, 0), inc
, 0))
3302 /* PREV_INSN used here to check the semi-open interval
3304 && ! reg_used_between_p (q
, PREV_INSN (insn
), incr
)
3305 /* We must also check for sets of q as q may be
3306 a call clobbered hard register and there may
3307 be a call between PREV_INSN (insn) and incr. */
3308 && ! reg_set_between_p (q
, PREV_INSN (insn
), incr
))
3310 /* We have *p followed sometime later by q = p+size.
3311 Both p and q must be live afterward,
3312 and q is not used between INSN and its assignment.
3313 Change it to q = p, ...*q..., q = q+size.
3314 Then fall into the usual case. */
3318 emit_move_insn (q
, incr_reg
);
3319 insns
= get_insns ();
3322 /* If we can't make the auto-inc, or can't make the
3323 replacement into Y, exit. There's no point in making
3324 the change below if we can't do the auto-inc and doing
3325 so is not correct in the pre-inc case. */
3328 validate_change (insn
, &XEXP (mem
, 0), inc
, 1);
3329 validate_change (incr
, &XEXP (y
, opnum
), q
, 1);
3330 if (! apply_change_group ())
3333 /* We now know we'll be doing this change, so emit the
3334 new insn(s) and do the updates. */
3335 emit_insn_before (insns
, insn
);
3337 if (BB_HEAD (pbi
->bb
) == insn
)
3338 BB_HEAD (pbi
->bb
) = insns
;
3340 /* INCR will become a NOTE and INSN won't contain a
3341 use of INCR_REG. If a use of INCR_REG was just placed in
3342 the insn before INSN, make that the next use.
3343 Otherwise, invalidate it. */
3344 if (NONJUMP_INSN_P (PREV_INSN (insn
))
3345 && GET_CODE (PATTERN (PREV_INSN (insn
))) == SET
3346 && SET_SRC (PATTERN (PREV_INSN (insn
))) == incr_reg
)
3347 pbi
->reg_next_use
[regno
] = PREV_INSN (insn
);
3349 pbi
->reg_next_use
[regno
] = 0;
3354 if ((pbi
->flags
& PROP_REG_INFO
)
3355 && !REGNO_REG_SET_P (pbi
->reg_live
, regno
))
3356 reg_deaths
[regno
] = pbi
->insn_num
;
3358 /* REGNO is now used in INCR which is below INSN, but
3359 it previously wasn't live here. If we don't mark
3360 it as live, we'll put a REG_DEAD note for it
3361 on this insn, which is incorrect. */
3362 SET_REGNO_REG_SET (pbi
->reg_live
, regno
);
3364 /* If there are any calls between INSN and INCR, show
3365 that REGNO now crosses them. */
3366 for (temp
= insn
; temp
!= incr
; temp
= NEXT_INSN (temp
))
3368 REG_N_CALLS_CROSSED (regno
)++;
3370 /* Invalidate alias info for Q since we just changed its value. */
3371 clear_reg_alias_info (q
);
3376 /* If we haven't returned, it means we were able to make the
3377 auto-inc, so update the status. First, record that this insn
3378 has an implicit side effect. */
3380 REG_NOTES (insn
) = alloc_EXPR_LIST (REG_INC
, incr_reg
, REG_NOTES (insn
));
3382 /* Modify the old increment-insn to simply copy
3383 the already-incremented value of our register. */
3384 changed
= validate_change (incr
, &SET_SRC (set
), incr_reg
, 0);
3385 gcc_assert (changed
);
3387 /* If that makes it a no-op (copying the register into itself) delete
3388 it so it won't appear to be a "use" and a "set" of this
3390 if (REGNO (SET_DEST (set
)) == REGNO (incr_reg
))
3392 /* If the original source was dead, it's dead now. */
3395 while ((note
= find_reg_note (incr
, REG_DEAD
, NULL_RTX
)) != NULL_RTX
)
3397 remove_note (incr
, note
);
3398 if (XEXP (note
, 0) != incr_reg
)
3400 unsigned int regno
= REGNO (XEXP (note
, 0));
3402 if ((pbi
->flags
& PROP_REG_INFO
)
3403 && REGNO_REG_SET_P (pbi
->reg_live
, regno
))
3405 REG_LIVE_LENGTH (regno
) += pbi
->insn_num
- reg_deaths
[regno
];
3406 reg_deaths
[regno
] = 0;
3408 CLEAR_REGNO_REG_SET (pbi
->reg_live
, REGNO (XEXP (note
, 0)));
3412 SET_INSN_DELETED (incr
);
3415 if (regno
>= FIRST_PSEUDO_REGISTER
)
3417 /* Count an extra reference to the reg. When a reg is
3418 incremented, spilling it is worse, so we want to make
3419 that less likely. */
3420 REG_FREQ (regno
) += REG_FREQ_FROM_BB (pbi
->bb
);
3422 /* Count the increment as a setting of the register,
3423 even though it isn't a SET in rtl. */
3424 REG_N_SETS (regno
)++;
3428 /* X is a MEM found in INSN. See if we can convert it into an auto-increment
3432 find_auto_inc (struct propagate_block_info
*pbi
, rtx x
, rtx insn
)
3434 rtx addr
= XEXP (x
, 0);
3435 HOST_WIDE_INT offset
= 0;
3436 rtx set
, y
, incr
, inc_val
;
3438 int size
= GET_MODE_SIZE (GET_MODE (x
));
3443 /* Here we detect use of an index register which might be good for
3444 postincrement, postdecrement, preincrement, or predecrement. */
3446 if (GET_CODE (addr
) == PLUS
&& GET_CODE (XEXP (addr
, 1)) == CONST_INT
)
3447 offset
= INTVAL (XEXP (addr
, 1)), addr
= XEXP (addr
, 0);
3452 regno
= REGNO (addr
);
3454 /* Is the next use an increment that might make auto-increment? */
3455 incr
= pbi
->reg_next_use
[regno
];
3456 if (incr
== 0 || BLOCK_NUM (incr
) != BLOCK_NUM (insn
))
3458 set
= single_set (incr
);
3459 if (set
== 0 || GET_CODE (set
) != SET
)
3463 if (GET_CODE (y
) != PLUS
)
3466 if (REG_P (XEXP (y
, 0)) && REGNO (XEXP (y
, 0)) == REGNO (addr
))
3467 inc_val
= XEXP (y
, 1);
3468 else if (REG_P (XEXP (y
, 1)) && REGNO (XEXP (y
, 1)) == REGNO (addr
))
3469 inc_val
= XEXP (y
, 0);
3473 if (GET_CODE (inc_val
) == CONST_INT
)
3475 if (HAVE_POST_INCREMENT
3476 && (INTVAL (inc_val
) == size
&& offset
== 0))
3477 attempt_auto_inc (pbi
, gen_rtx_POST_INC (Pmode
, addr
), insn
, x
,
3479 else if (HAVE_POST_DECREMENT
3480 && (INTVAL (inc_val
) == -size
&& offset
== 0))
3481 attempt_auto_inc (pbi
, gen_rtx_POST_DEC (Pmode
, addr
), insn
, x
,
3483 else if (HAVE_PRE_INCREMENT
3484 && (INTVAL (inc_val
) == size
&& offset
== size
))
3485 attempt_auto_inc (pbi
, gen_rtx_PRE_INC (Pmode
, addr
), insn
, x
,
3487 else if (HAVE_PRE_DECREMENT
3488 && (INTVAL (inc_val
) == -size
&& offset
== -size
))
3489 attempt_auto_inc (pbi
, gen_rtx_PRE_DEC (Pmode
, addr
), insn
, x
,
3491 else if (HAVE_POST_MODIFY_DISP
&& offset
== 0)
3492 attempt_auto_inc (pbi
, gen_rtx_POST_MODIFY (Pmode
, addr
,
3493 gen_rtx_PLUS (Pmode
,
3496 insn
, x
, incr
, addr
);
3497 else if (HAVE_PRE_MODIFY_DISP
&& offset
== INTVAL (inc_val
))
3498 attempt_auto_inc (pbi
, gen_rtx_PRE_MODIFY (Pmode
, addr
,
3499 gen_rtx_PLUS (Pmode
,
3502 insn
, x
, incr
, addr
);
3504 else if (REG_P (inc_val
)
3505 && ! reg_set_between_p (inc_val
, PREV_INSN (insn
),
3509 if (HAVE_POST_MODIFY_REG
&& offset
== 0)
3510 attempt_auto_inc (pbi
, gen_rtx_POST_MODIFY (Pmode
, addr
,
3511 gen_rtx_PLUS (Pmode
,
3514 insn
, x
, incr
, addr
);
3518 #endif /* AUTO_INC_DEC */
3521 mark_used_reg (struct propagate_block_info
*pbi
, rtx reg
,
3522 rtx cond ATTRIBUTE_UNUSED
, rtx insn
)
3524 unsigned int regno_first
, regno_last
, i
;
3525 int some_was_live
, some_was_dead
, some_not_set
;
3527 regno_last
= regno_first
= REGNO (reg
);
3528 if (regno_first
< FIRST_PSEUDO_REGISTER
)
3529 regno_last
+= hard_regno_nregs
[regno_first
][GET_MODE (reg
)] - 1;
3531 /* Find out if any of this register is live after this instruction. */
3532 some_was_live
= some_was_dead
= 0;
3533 for (i
= regno_first
; i
<= regno_last
; ++i
)
3535 int needed_regno
= REGNO_REG_SET_P (pbi
->reg_live
, i
);
3536 some_was_live
|= needed_regno
;
3537 some_was_dead
|= ! needed_regno
;
3540 /* Find out if any of the register was set this insn. */
3542 for (i
= regno_first
; i
<= regno_last
; ++i
)
3543 some_not_set
|= ! REGNO_REG_SET_P (pbi
->new_set
, i
);
3545 if (pbi
->flags
& (PROP_LOG_LINKS
| PROP_AUTOINC
))
3547 /* Record where each reg is used, so when the reg is set we know
3548 the next insn that uses it. */
3549 pbi
->reg_next_use
[regno_first
] = insn
;
3552 if (pbi
->flags
& PROP_REG_INFO
)
3554 if (regno_first
< FIRST_PSEUDO_REGISTER
)
3556 /* If this is a register we are going to try to eliminate,
3557 don't mark it live here. If we are successful in
3558 eliminating it, it need not be live unless it is used for
3559 pseudos, in which case it will have been set live when it
3560 was allocated to the pseudos. If the register will not
3561 be eliminated, reload will set it live at that point.
3563 Otherwise, record that this function uses this register. */
3564 /* ??? The PPC backend tries to "eliminate" on the pic
3565 register to itself. This should be fixed. In the mean
3566 time, hack around it. */
3568 if (! (TEST_HARD_REG_BIT (elim_reg_set
, regno_first
)
3569 && (regno_first
== FRAME_POINTER_REGNUM
3570 || regno_first
== ARG_POINTER_REGNUM
)))
3571 for (i
= regno_first
; i
<= regno_last
; ++i
)
3572 regs_ever_live
[i
] = 1;
3576 /* Keep track of which basic block each reg appears in. */
3578 int blocknum
= pbi
->bb
->index
;
3579 if (REG_BASIC_BLOCK (regno_first
) == REG_BLOCK_UNKNOWN
)
3580 REG_BASIC_BLOCK (regno_first
) = blocknum
;
3581 else if (REG_BASIC_BLOCK (regno_first
) != blocknum
)
3582 REG_BASIC_BLOCK (regno_first
) = REG_BLOCK_GLOBAL
;
3584 /* Count (weighted) number of uses of each reg. */
3585 REG_FREQ (regno_first
) += REG_FREQ_FROM_BB (pbi
->bb
);
3586 REG_N_REFS (regno_first
)++;
3588 for (i
= regno_first
; i
<= regno_last
; ++i
)
3589 if (! REGNO_REG_SET_P (pbi
->reg_live
, i
))
3591 gcc_assert (!reg_deaths
[i
]);
3592 reg_deaths
[i
] = pbi
->insn_num
;
3596 /* Record and count the insns in which a reg dies. If it is used in
3597 this insn and was dead below the insn then it dies in this insn.
3598 If it was set in this insn, we do not make a REG_DEAD note;
3599 likewise if we already made such a note. */
3600 if ((pbi
->flags
& (PROP_DEATH_NOTES
| PROP_REG_INFO
))
3604 /* Check for the case where the register dying partially
3605 overlaps the register set by this insn. */
3606 if (regno_first
!= regno_last
)
3607 for (i
= regno_first
; i
<= regno_last
; ++i
)
3608 some_was_live
|= REGNO_REG_SET_P (pbi
->new_set
, i
);
3610 /* If none of the words in X is needed, make a REG_DEAD note.
3611 Otherwise, we must make partial REG_DEAD notes. */
3612 if (! some_was_live
)
3614 if ((pbi
->flags
& PROP_DEATH_NOTES
)
3615 && ! find_regno_note (insn
, REG_DEAD
, regno_first
))
3617 = alloc_EXPR_LIST (REG_DEAD
, reg
, REG_NOTES (insn
));
3619 if (pbi
->flags
& PROP_REG_INFO
)
3620 REG_N_DEATHS (regno_first
)++;
3624 /* Don't make a REG_DEAD note for a part of a register
3625 that is set in the insn. */
3626 for (i
= regno_first
; i
<= regno_last
; ++i
)
3627 if (! REGNO_REG_SET_P (pbi
->reg_live
, i
)
3628 && ! dead_or_set_regno_p (insn
, i
))
3630 = alloc_EXPR_LIST (REG_DEAD
,
3636 /* Mark the register as being live. */
3637 for (i
= regno_first
; i
<= regno_last
; ++i
)
3639 #ifdef HAVE_conditional_execution
3640 int this_was_live
= REGNO_REG_SET_P (pbi
->reg_live
, i
);
3643 SET_REGNO_REG_SET (pbi
->reg_live
, i
);
3645 #ifdef HAVE_conditional_execution
3646 /* If this is a conditional use, record that fact. If it is later
3647 conditionally set, we'll know to kill the register. */
3648 if (cond
!= NULL_RTX
)
3650 splay_tree_node node
;
3651 struct reg_cond_life_info
*rcli
;
3656 node
= splay_tree_lookup (pbi
->reg_cond_dead
, i
);
3659 /* The register was unconditionally live previously.
3660 No need to do anything. */
3664 /* The register was conditionally live previously.
3665 Subtract the new life cond from the old death cond. */
3666 rcli
= (struct reg_cond_life_info
*) node
->value
;
3667 ncond
= rcli
->condition
;
3668 ncond
= and_reg_cond (ncond
, not_reg_cond (cond
), 1);
3670 /* If the register is now unconditionally live,
3671 remove the entry in the splay_tree. */
3672 if (ncond
== const0_rtx
)
3673 splay_tree_remove (pbi
->reg_cond_dead
, i
);
3676 rcli
->condition
= ncond
;
3677 SET_REGNO_REG_SET (pbi
->reg_cond_reg
,
3678 REGNO (XEXP (cond
, 0)));
3684 /* The register was not previously live at all. Record
3685 the condition under which it is still dead. */
3686 rcli
= xmalloc (sizeof (*rcli
));
3687 rcli
->condition
= not_reg_cond (cond
);
3688 rcli
->stores
= const0_rtx
;
3689 rcli
->orig_condition
= const0_rtx
;
3690 splay_tree_insert (pbi
->reg_cond_dead
, i
,
3691 (splay_tree_value
) rcli
);
3693 SET_REGNO_REG_SET (pbi
->reg_cond_reg
, REGNO (XEXP (cond
, 0)));
3696 else if (this_was_live
)
3698 /* The register may have been conditionally live previously, but
3699 is now unconditionally live. Remove it from the conditionally
3700 dead list, so that a conditional set won't cause us to think
3702 splay_tree_remove (pbi
->reg_cond_dead
, i
);
3708 /* Scan expression X and store a 1-bit in NEW_LIVE for each reg it uses.
3709 This is done assuming the registers needed from X are those that
3710 have 1-bits in PBI->REG_LIVE.
3712 INSN is the containing instruction. If INSN is dead, this function
3716 mark_used_regs (struct propagate_block_info
*pbi
, rtx x
, rtx cond
, rtx insn
)
3720 int flags
= pbi
->flags
;
3725 code
= GET_CODE (x
);
3746 /* If we are clobbering a MEM, mark any registers inside the address
3748 if (MEM_P (XEXP (x
, 0)))
3749 mark_used_regs (pbi
, XEXP (XEXP (x
, 0), 0), cond
, insn
);
3753 /* Don't bother watching stores to mems if this is not the
3754 final pass. We'll not be deleting dead stores this round. */
3755 if (optimize
&& (flags
& PROP_SCAN_DEAD_STORES
))
3757 /* Invalidate the data for the last MEM stored, but only if MEM is
3758 something that can be stored into. */
3759 if (GET_CODE (XEXP (x
, 0)) == SYMBOL_REF
3760 && CONSTANT_POOL_ADDRESS_P (XEXP (x
, 0)))
3761 /* Needn't clear the memory set list. */
3765 rtx temp
= pbi
->mem_set_list
;
3766 rtx prev
= NULL_RTX
;
3771 next
= XEXP (temp
, 1);
3772 if (anti_dependence (XEXP (temp
, 0), x
))
3774 /* Splice temp out of the list. */
3776 XEXP (prev
, 1) = next
;
3778 pbi
->mem_set_list
= next
;
3779 free_EXPR_LIST_node (temp
);
3780 pbi
->mem_set_list_len
--;
3788 /* If the memory reference had embedded side effects (autoincrement
3789 address modes. Then we may need to kill some entries on the
3792 for_each_rtx (&PATTERN (insn
), invalidate_mems_from_autoinc
, pbi
);
3796 if (flags
& PROP_AUTOINC
)
3797 find_auto_inc (pbi
, x
, insn
);
3802 #ifdef CANNOT_CHANGE_MODE_CLASS
3803 if (flags
& PROP_REG_INFO
)
3804 record_subregs_of_mode (x
);
3807 /* While we're here, optimize this case. */
3814 /* See a register other than being set => mark it as needed. */
3815 mark_used_reg (pbi
, x
, cond
, insn
);
3820 rtx testreg
= SET_DEST (x
);
3823 /* If storing into MEM, don't show it as being used. But do
3824 show the address as being used. */
3825 if (MEM_P (testreg
))
3828 if (flags
& PROP_AUTOINC
)
3829 find_auto_inc (pbi
, testreg
, insn
);
3831 mark_used_regs (pbi
, XEXP (testreg
, 0), cond
, insn
);
3832 mark_used_regs (pbi
, SET_SRC (x
), cond
, insn
);
3836 /* Storing in STRICT_LOW_PART is like storing in a reg
3837 in that this SET might be dead, so ignore it in TESTREG.
3838 but in some other ways it is like using the reg.
3840 Storing in a SUBREG or a bit field is like storing the entire
3841 register in that if the register's value is not used
3842 then this SET is not needed. */
3843 while (GET_CODE (testreg
) == STRICT_LOW_PART
3844 || GET_CODE (testreg
) == ZERO_EXTRACT
3845 || GET_CODE (testreg
) == SIGN_EXTRACT
3846 || GET_CODE (testreg
) == SUBREG
)
3848 #ifdef CANNOT_CHANGE_MODE_CLASS
3849 if ((flags
& PROP_REG_INFO
) && GET_CODE (testreg
) == SUBREG
)
3850 record_subregs_of_mode (testreg
);
3853 /* Modifying a single register in an alternate mode
3854 does not use any of the old value. But these other
3855 ways of storing in a register do use the old value. */
3856 if (GET_CODE (testreg
) == SUBREG
3857 && !((REG_BYTES (SUBREG_REG (testreg
))
3858 + UNITS_PER_WORD
- 1) / UNITS_PER_WORD
3859 > (REG_BYTES (testreg
)
3860 + UNITS_PER_WORD
- 1) / UNITS_PER_WORD
))
3865 testreg
= XEXP (testreg
, 0);
3868 /* If this is a store into a register or group of registers,
3869 recursively scan the value being stored. */
3871 if ((GET_CODE (testreg
) == PARALLEL
3872 && GET_MODE (testreg
) == BLKmode
)
3874 && (regno
= REGNO (testreg
),
3875 ! (regno
== FRAME_POINTER_REGNUM
3876 && (! reload_completed
|| frame_pointer_needed
)))
3877 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
3878 && ! (regno
== HARD_FRAME_POINTER_REGNUM
3879 && (! reload_completed
|| frame_pointer_needed
))
3881 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
3882 && ! (regno
== ARG_POINTER_REGNUM
&& fixed_regs
[regno
])
3887 mark_used_regs (pbi
, SET_DEST (x
), cond
, insn
);
3888 mark_used_regs (pbi
, SET_SRC (x
), cond
, insn
);
3895 case UNSPEC_VOLATILE
:
3899 /* Traditional and volatile asm instructions must be considered to use
3900 and clobber all hard registers, all pseudo-registers and all of
3901 memory. So must TRAP_IF and UNSPEC_VOLATILE operations.
3903 Consider for instance a volatile asm that changes the fpu rounding
3904 mode. An insn should not be moved across this even if it only uses
3905 pseudo-regs because it might give an incorrectly rounded result.
3907 ?!? Unfortunately, marking all hard registers as live causes massive
3908 problems for the register allocator and marking all pseudos as live
3909 creates mountains of uninitialized variable warnings.
3911 So for now, just clear the memory set list and mark any regs
3912 we can find in ASM_OPERANDS as used. */
3913 if (code
!= ASM_OPERANDS
|| MEM_VOLATILE_P (x
))
3915 free_EXPR_LIST_list (&pbi
->mem_set_list
);
3916 pbi
->mem_set_list_len
= 0;
3919 /* For all ASM_OPERANDS, we must traverse the vector of input operands.
3920 We can not just fall through here since then we would be confused
3921 by the ASM_INPUT rtx inside ASM_OPERANDS, which do not indicate
3922 traditional asms unlike their normal usage. */
3923 if (code
== ASM_OPERANDS
)
3927 for (j
= 0; j
< ASM_OPERANDS_INPUT_LENGTH (x
); j
++)
3928 mark_used_regs (pbi
, ASM_OPERANDS_INPUT (x
, j
), cond
, insn
);
3936 mark_used_regs (pbi
, COND_EXEC_TEST (x
), NULL_RTX
, insn
);
3938 cond
= COND_EXEC_TEST (x
);
3939 x
= COND_EXEC_CODE (x
);
3946 /* Recursively scan the operands of this expression. */
3949 const char * const fmt
= GET_RTX_FORMAT (code
);
3952 for (i
= GET_RTX_LENGTH (code
) - 1; i
>= 0; i
--)
3956 /* Tail recursive case: save a function call level. */
3962 mark_used_regs (pbi
, XEXP (x
, i
), cond
, insn
);
3964 else if (fmt
[i
] == 'E')
3967 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
3968 mark_used_regs (pbi
, XVECEXP (x
, i
, j
), cond
, insn
);
3977 try_pre_increment_1 (struct propagate_block_info
*pbi
, rtx insn
)
3979 /* Find the next use of this reg. If in same basic block,
3980 make it do pre-increment or pre-decrement if appropriate. */
3981 rtx x
= single_set (insn
);
3982 HOST_WIDE_INT amount
= ((GET_CODE (SET_SRC (x
)) == PLUS
? 1 : -1)
3983 * INTVAL (XEXP (SET_SRC (x
), 1)));
3984 int regno
= REGNO (SET_DEST (x
));
3985 rtx y
= pbi
->reg_next_use
[regno
];
3987 && SET_DEST (x
) != stack_pointer_rtx
3988 && BLOCK_NUM (y
) == BLOCK_NUM (insn
)
3989 /* Don't do this if the reg dies, or gets set in y; a standard addressing
3990 mode would be better. */
3991 && ! dead_or_set_p (y
, SET_DEST (x
))
3992 && try_pre_increment (y
, SET_DEST (x
), amount
))
3994 /* We have found a suitable auto-increment and already changed
3995 insn Y to do it. So flush this increment instruction. */
3996 propagate_block_delete_insn (insn
);
3998 /* Count a reference to this reg for the increment insn we are
3999 deleting. When a reg is incremented, spilling it is worse,
4000 so we want to make that less likely. */
4001 if (regno
>= FIRST_PSEUDO_REGISTER
)
4003 REG_FREQ (regno
) += REG_FREQ_FROM_BB (pbi
->bb
);
4004 REG_N_SETS (regno
)++;
4007 /* Flush any remembered memories depending on the value of
4008 the incremented register. */
4009 invalidate_mems_from_set (pbi
, SET_DEST (x
));
4016 /* Try to change INSN so that it does pre-increment or pre-decrement
4017 addressing on register REG in order to add AMOUNT to REG.
4018 AMOUNT is negative for pre-decrement.
4019 Returns 1 if the change could be made.
4020 This checks all about the validity of the result of modifying INSN. */
4023 try_pre_increment (rtx insn
, rtx reg
, HOST_WIDE_INT amount
)
4027 /* Nonzero if we can try to make a pre-increment or pre-decrement.
4028 For example, addl $4,r1; movl (r1),... can become movl +(r1),... */
4030 /* Nonzero if we can try to make a post-increment or post-decrement.
4031 For example, addl $4,r1; movl -4(r1),... can become movl (r1)+,...
4032 It is possible for both PRE_OK and POST_OK to be nonzero if the machine
4033 supports both pre-inc and post-inc, or both pre-dec and post-dec. */
4036 /* Nonzero if the opportunity actually requires post-inc or post-dec. */
4039 /* From the sign of increment, see which possibilities are conceivable
4040 on this target machine. */
4041 if (HAVE_PRE_INCREMENT
&& amount
> 0)
4043 if (HAVE_POST_INCREMENT
&& amount
> 0)
4046 if (HAVE_PRE_DECREMENT
&& amount
< 0)
4048 if (HAVE_POST_DECREMENT
&& amount
< 0)
4051 if (! (pre_ok
|| post_ok
))
4054 /* It is not safe to add a side effect to a jump insn
4055 because if the incremented register is spilled and must be reloaded
4056 there would be no way to store the incremented value back in memory. */
4063 use
= find_use_as_address (PATTERN (insn
), reg
, 0);
4064 if (post_ok
&& (use
== 0 || use
== (rtx
) (size_t) 1))
4066 use
= find_use_as_address (PATTERN (insn
), reg
, -amount
);
4070 if (use
== 0 || use
== (rtx
) (size_t) 1)
4073 if (GET_MODE_SIZE (GET_MODE (use
)) != (amount
> 0 ? amount
: - amount
))
4076 /* See if this combination of instruction and addressing mode exists. */
4077 if (! validate_change (insn
, &XEXP (use
, 0),
4078 gen_rtx_fmt_e (amount
> 0
4079 ? (do_post
? POST_INC
: PRE_INC
)
4080 : (do_post
? POST_DEC
: PRE_DEC
),
4084 /* Record that this insn now has an implicit side effect on X. */
4085 REG_NOTES (insn
) = alloc_EXPR_LIST (REG_INC
, reg
, REG_NOTES (insn
));
4089 #endif /* AUTO_INC_DEC */
4091 /* Find the place in the rtx X where REG is used as a memory address.
4092 Return the MEM rtx that so uses it.
4093 If PLUSCONST is nonzero, search instead for a memory address equivalent to
4094 (plus REG (const_int PLUSCONST)).
4096 If such an address does not appear, return 0.
4097 If REG appears more than once, or is used other than in such an address,
4101 find_use_as_address (rtx x
, rtx reg
, HOST_WIDE_INT plusconst
)
4103 enum rtx_code code
= GET_CODE (x
);
4104 const char * const fmt
= GET_RTX_FORMAT (code
);
4109 if (code
== MEM
&& XEXP (x
, 0) == reg
&& plusconst
== 0)
4112 if (code
== MEM
&& GET_CODE (XEXP (x
, 0)) == PLUS
4113 && XEXP (XEXP (x
, 0), 0) == reg
4114 && GET_CODE (XEXP (XEXP (x
, 0), 1)) == CONST_INT
4115 && INTVAL (XEXP (XEXP (x
, 0), 1)) == plusconst
)
4118 if (code
== SIGN_EXTRACT
|| code
== ZERO_EXTRACT
)
4120 /* If REG occurs inside a MEM used in a bit-field reference,
4121 that is unacceptable. */
4122 if (find_use_as_address (XEXP (x
, 0), reg
, 0) != 0)
4123 return (rtx
) (size_t) 1;
4127 return (rtx
) (size_t) 1;
4129 for (i
= GET_RTX_LENGTH (code
) - 1; i
>= 0; i
--)
4133 tem
= find_use_as_address (XEXP (x
, i
), reg
, plusconst
);
4137 return (rtx
) (size_t) 1;
4139 else if (fmt
[i
] == 'E')
4142 for (j
= XVECLEN (x
, i
) - 1; j
>= 0; j
--)
4144 tem
= find_use_as_address (XVECEXP (x
, i
, j
), reg
, plusconst
);
4148 return (rtx
) (size_t) 1;
4156 /* Write information about registers and basic blocks into FILE.
4157 This is part of making a debugging dump. */
4160 dump_regset (regset r
, FILE *outf
)
4163 reg_set_iterator rsi
;
4167 fputs (" (nil)", outf
);
4171 EXECUTE_IF_SET_IN_REG_SET (r
, 0, i
, rsi
)
4173 fprintf (outf
, " %d", i
);
4174 if (i
< FIRST_PSEUDO_REGISTER
)
4175 fprintf (outf
, " [%s]",
4180 /* Print a human-readable representation of R on the standard error
4181 stream. This function is designed to be used from within the
4185 debug_regset (regset r
)
4187 dump_regset (r
, stderr
);
4188 putc ('\n', stderr
);
4191 /* Recompute register set/reference counts immediately prior to register
4194 This avoids problems with set/reference counts changing to/from values
4195 which have special meanings to the register allocators.
4197 Additionally, the reference counts are the primary component used by the
4198 register allocators to prioritize pseudos for allocation to hard regs.
4199 More accurate reference counts generally lead to better register allocation.
4201 F is the first insn to be scanned.
4203 LOOP_STEP denotes how much loop_depth should be incremented per
4204 loop nesting level in order to increase the ref count more for
4205 references in a loop.
4207 It might be worthwhile to update REG_LIVE_LENGTH, REG_BASIC_BLOCK and
4208 possibly other information which is used by the register allocators. */
4211 recompute_reg_usage (rtx f ATTRIBUTE_UNUSED
, int loop_step ATTRIBUTE_UNUSED
)
4213 allocate_reg_life_data ();
4214 /* distribute_notes in combiner fails to convert some of the REG_UNUSED notes
4215 to REG_DEAD notes. This causes CHECK_DEAD_NOTES in sched1 to abort. To
4216 solve this update the DEATH_NOTES here. */
4217 update_life_info (NULL
, UPDATE_LIFE_LOCAL
, PROP_REG_INFO
| PROP_DEATH_NOTES
);
4220 /* Optionally removes all the REG_DEAD and REG_UNUSED notes from a set of
4221 blocks. If BLOCKS is NULL, assume the universal set. Returns a count
4222 of the number of registers that died. */
4225 count_or_remove_death_notes (sbitmap blocks
, int kill
)
4231 /* This used to be a loop over all the blocks with a membership test
4232 inside the loop. That can be amazingly expensive on a large CFG
4233 when only a small number of bits are set in BLOCKs (for example,
4234 the calls from the scheduler typically have very few bits set).
4236 For extra credit, someone should convert BLOCKS to a bitmap rather
4240 EXECUTE_IF_SET_IN_SBITMAP (blocks
, 0, i
,
4242 count
+= count_or_remove_death_notes_bb (BASIC_BLOCK (i
), kill
);
4249 count
+= count_or_remove_death_notes_bb (bb
, kill
);
4256 /* Optionally removes all the REG_DEAD and REG_UNUSED notes from basic
4257 block BB. Returns a count of the number of registers that died. */
4260 count_or_remove_death_notes_bb (basic_block bb
, int kill
)
4265 for (insn
= BB_HEAD (bb
); ; insn
= NEXT_INSN (insn
))
4269 rtx
*pprev
= ®_NOTES (insn
);
4274 switch (REG_NOTE_KIND (link
))
4277 if (REG_P (XEXP (link
, 0)))
4279 rtx reg
= XEXP (link
, 0);
4282 if (REGNO (reg
) >= FIRST_PSEUDO_REGISTER
)
4285 n
= hard_regno_nregs
[REGNO (reg
)][GET_MODE (reg
)];
4294 rtx next
= XEXP (link
, 1);
4295 free_EXPR_LIST_node (link
);
4296 *pprev
= link
= next
;
4302 pprev
= &XEXP (link
, 1);
4309 if (insn
== BB_END (bb
))
4316 /* Clear LOG_LINKS fields of insns in a selected blocks or whole chain
4317 if blocks is NULL. */
4320 clear_log_links (sbitmap blocks
)
4327 for (insn
= get_insns (); insn
; insn
= NEXT_INSN (insn
))
4329 free_INSN_LIST_list (&LOG_LINKS (insn
));
4332 EXECUTE_IF_SET_IN_SBITMAP (blocks
, 0, i
,
4334 basic_block bb
= BASIC_BLOCK (i
);
4336 for (insn
= BB_HEAD (bb
); insn
!= NEXT_INSN (BB_END (bb
));
4337 insn
= NEXT_INSN (insn
))
4339 free_INSN_LIST_list (&LOG_LINKS (insn
));
4343 /* Given a register bitmap, turn on the bits in a HARD_REG_SET that
4344 correspond to the hard registers, if any, set in that map. This
4345 could be done far more efficiently by having all sorts of special-cases
4346 with moving single words, but probably isn't worth the trouble. */
4349 reg_set_to_hard_reg_set (HARD_REG_SET
*to
, bitmap from
)
4354 EXECUTE_IF_SET_IN_BITMAP (from
, 0, i
, bi
)
4356 if (i
>= FIRST_PSEUDO_REGISTER
)
4358 SET_HARD_REG_BIT (*to
, i
);