1 /* Data flow analysis for GNU compiler.
2 Copyright (C) 1987, 1988, 1992 Free Software Foundation, Inc.
4 This file is part of GNU CC.
6 GNU CC is free software; you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by
8 the Free Software Foundation; either version 2, or (at your option)
11 GNU CC is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 GNU General Public License for more details.
16 You should have received a copy of the GNU General Public License
17 along with GNU CC; see the file COPYING. If not, write to
18 the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. */
21 /* This file contains the data flow analysis pass of the compiler.
22 It computes data flow information
23 which tells combine_instructions which insns to consider combining
24 and controls register allocation.
26 Additional data flow information that is too bulky to record
27 is generated during the analysis, and is used at that time to
28 create 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
37 into basic blocks. It records the beginnings and ends of the
38 basic blocks in the vectors basic_block_head and basic_block_end,
39 and the number of blocks in n_basic_blocks.
41 find_basic_blocks also finds any unreachable loops
46 life_analysis is called immediately after find_basic_blocks.
47 It uses the basic block information to determine where each
48 hard or pseudo register is live.
50 ** live-register info **
52 The information about where each register is live is in two parts:
53 the REG_NOTES of insns, and the vector basic_block_live_at_start.
55 basic_block_live_at_start has an element for each basic block,
56 and the element is a bit-vector with a bit for each hard or pseudo
57 register. The bit is 1 if the register is live at the beginning
60 Two types of elements can be added to an insn's REG_NOTES.
61 A REG_DEAD note is added to an insn's REG_NOTES for any register
62 that meets both of two conditions: The value in the register is not
63 needed in subsequent insns and the insn does not replace the value in
64 the register (in the case of multi-word hard registers, the value in
65 each register must be replaced by the insn to avoid a REG_DEAD note).
67 In the vast majority of cases, an object in a REG_DEAD note will be
68 used somewhere in the insn. The (rare) exception to this is if an
69 insn uses a multi-word hard register and only some of the registers are
70 needed in subsequent insns. In that case, REG_DEAD notes will be
71 provided for those hard registers that are not subsequently needed.
72 Partial REG_DEAD notes of this type do not occur when an insn sets
73 only some of the hard registers used in such a multi-word operand;
74 omitting REG_DEAD notes for objects stored in an insn is optional and
75 the desire to do so does not justify the complexity of the partial
78 REG_UNUSED notes are added for each register that is set by the insn
79 but is unused subsequently (if every register set by the insn is unused
80 and the insn does not reference memory or have some other side-effect,
81 the insn is deleted instead). If only part of a multi-word hard
82 register is used in a subsequent insn, REG_UNUSED notes are made for
83 the parts that will not be used.
85 To determine which registers are live after any insn, one can
86 start from the beginning of the basic block and scan insns, noting
87 which registers are set by each insn and which die there.
89 ** Other actions of life_analysis **
91 life_analysis sets up the LOG_LINKS fields of insns because the
92 information needed to do so is readily available.
94 life_analysis deletes insns whose only effect is to store a value
97 life_analysis notices cases where a reference to a register as
98 a memory address can be combined with a preceding or following
99 incrementation or decrementation of the register. The separate
100 instruction to increment or decrement is deleted and the address
101 is changed to a POST_INC or similar rtx.
103 Each time an incrementing or decrementing address is created,
104 a REG_INC element is added to the insn's REG_NOTES list.
106 life_analysis fills in certain vectors containing information about
107 register usage: reg_n_refs, reg_n_deaths, reg_n_sets, reg_live_length,
108 reg_n_calls_crosses and reg_basic_block. */
113 #include "basic-block.h"
114 #include "insn-config.h"
116 #include "hard-reg-set.h"
121 #define obstack_chunk_alloc xmalloc
122 #define obstack_chunk_free free
124 /* List of labels that must never be deleted. */
125 extern rtx forced_labels
;
127 /* Get the basic block number of an insn.
128 This info should not be expected to remain available
129 after the end of life_analysis. */
131 /* This is the limit of the allocated space in the following two arrays. */
133 static int max_uid_for_flow
;
135 #define BLOCK_NUM(INSN) uid_block_number[INSN_UID (INSN)]
137 /* This is where the BLOCK_NUM values are really stored.
138 This is set up by find_basic_blocks and used there and in life_analysis,
141 static short *uid_block_number
;
143 /* INSN_VOLATILE (insn) is 1 if the insn refers to anything volatile. */
145 #define INSN_VOLATILE(INSN) uid_volatile[INSN_UID (INSN)]
146 static char *uid_volatile
;
148 /* Number of basic blocks in the current function. */
152 /* Maximum register number used in this function, plus one. */
156 /* Maximum number of SCRATCH rtx's used in any basic block of this function. */
160 /* Number of SCRATCH rtx's in the current block. */
162 static int num_scratch
;
164 /* Indexed by n, gives number of basic block that (REG n) is used in.
165 If the value is REG_BLOCK_GLOBAL (-2),
166 it means (REG n) is used in more than one basic block.
167 REG_BLOCK_UNKNOWN (-1) means it hasn't been seen yet so we don't know.
168 This information remains valid for the rest of the compilation
169 of the current function; it is used to control register allocation. */
171 short *reg_basic_block
;
173 /* Indexed by n, gives number of times (REG n) is used or set, each
174 weighted by its loop-depth.
175 This information remains valid for the rest of the compilation
176 of the current function; it is used to control register allocation. */
180 /* Indexed by N, gives number of places register N dies.
181 This information remains valid for the rest of the compilation
182 of the current function; it is used to control register allocation. */
186 /* Indexed by N, gives 1 if that reg is live across any CALL_INSNs.
187 This information remains valid for the rest of the compilation
188 of the current function; it is used to control register allocation. */
190 int *reg_n_calls_crossed
;
192 /* Total number of instructions at which (REG n) is live.
193 The larger this is, the less priority (REG n) gets for
194 allocation in a real register.
195 This information remains valid for the rest of the compilation
196 of the current function; it is used to control register allocation.
198 local-alloc.c may alter this number to change the priority.
200 Negative values are special.
201 -1 is used to mark a pseudo reg which has a constant or memory equivalent
202 and is used infrequently enough that it should not get a hard register.
203 -2 is used to mark a pseudo reg for a parameter, when a frame pointer
204 is not required. global-alloc.c makes an allocno for this but does
205 not try to assign a hard register to it. */
207 int *reg_live_length
;
209 /* Element N is the next insn that uses (hard or pseudo) register number N
210 within the current basic block; or zero, if there is no such insn.
211 This is valid only during the final backward scan in propagate_block. */
213 static rtx
*reg_next_use
;
215 /* Size of a regset for the current function,
216 in (1) bytes and (2) elements. */
221 /* Element N is first insn in basic block N.
222 This info lasts until we finish compiling the function. */
224 rtx
*basic_block_head
;
226 /* Element N is last insn in basic block N.
227 This info lasts until we finish compiling the function. */
229 rtx
*basic_block_end
;
231 /* Element N is a regset describing the registers live
232 at the start of basic block N.
233 This info lasts until we finish compiling the function. */
235 regset
*basic_block_live_at_start
;
237 /* Regset of regs live when calls to `setjmp'-like functions happen. */
239 regset regs_live_at_setjmp
;
241 /* List made of EXPR_LIST rtx's which gives pairs of pseudo registers
242 that have to go in the same hard reg.
243 The first two regs in the list are a pair, and the next two
244 are another pair, etc. */
247 /* Element N is nonzero if control can drop into basic block N
248 from the preceding basic block. Freed after life_analysis. */
250 static char *basic_block_drops_in
;
252 /* Element N is depth within loops of the last insn in basic block number N.
253 Freed after life_analysis. */
255 static short *basic_block_loop_depth
;
257 /* Element N nonzero if basic block N can actually be reached.
258 Vector exists only during find_basic_blocks. */
260 static char *block_live_static
;
262 /* Depth within loops of basic block being scanned for lifetime analysis,
263 plus one. This is the weight attached to references to registers. */
265 static int loop_depth
;
267 /* During propagate_block, this is non-zero if the value of CC0 is live. */
271 /* During propagate_block, this contains the last MEM stored into. It
272 is used to eliminate consecutive stores to the same location. */
274 static rtx last_mem_set
;
276 /* Set of registers that may be eliminable. These are handled specially
277 in updating regs_ever_live. */
279 static HARD_REG_SET elim_reg_set
;
281 /* Forward declarations */
282 static void find_basic_blocks ();
283 static void life_analysis ();
284 static void mark_label_ref ();
285 void allocate_for_life_analysis (); /* Used also in stupid_life_analysis */
286 static void init_regset_vector ();
287 static void propagate_block ();
288 static void mark_set_regs ();
289 static void mark_used_regs ();
290 static int insn_dead_p ();
291 static int libcall_dead_p ();
292 static int try_pre_increment ();
293 static int try_pre_increment_1 ();
294 static rtx
find_use_as_address ();
295 void dump_flow_info ();
297 /* Find basic blocks of the current function and perform data flow analysis.
298 F is the first insn of the function and NREGS the number of register numbers
302 flow_analysis (f
, nregs
, file
)
309 rtx nonlocal_label_list
= nonlocal_label_rtx_list ();
311 #ifdef ELIMINABLE_REGS
312 static struct {int from
, to
; } eliminables
[] = ELIMINABLE_REGS
;
315 /* Record which registers will be eliminated. We use this in
318 CLEAR_HARD_REG_SET (elim_reg_set
);
320 #ifdef ELIMINABLE_REGS
321 for (i
= 0; i
< sizeof eliminables
/ sizeof eliminables
[0]; i
++)
322 SET_HARD_REG_BIT (elim_reg_set
, eliminables
[i
].from
);
324 SET_HARD_REG_BIT (elim_reg_set
, FRAME_POINTER_REGNUM
);
327 /* Count the basic blocks. Also find maximum insn uid value used. */
330 register RTX_CODE prev_code
= JUMP_INSN
;
331 register RTX_CODE code
;
333 max_uid_for_flow
= 0;
335 for (insn
= f
, i
= 0; insn
; insn
= NEXT_INSN (insn
))
337 code
= GET_CODE (insn
);
338 if (INSN_UID (insn
) > max_uid_for_flow
)
339 max_uid_for_flow
= INSN_UID (insn
);
340 if (code
== CODE_LABEL
341 || (GET_RTX_CLASS (code
) == 'i'
342 && (prev_code
== JUMP_INSN
343 || (prev_code
== CALL_INSN
344 && nonlocal_label_list
!= 0)
345 || prev_code
== BARRIER
)))
353 /* Leave space for insns we make in some cases for auto-inc. These cases
354 are rare, so we don't need too much space. */
355 max_uid_for_flow
+= max_uid_for_flow
/ 10;
358 /* Allocate some tables that last till end of compiling this function
359 and some needed only in find_basic_blocks and life_analysis. */
362 basic_block_head
= (rtx
*) oballoc (n_basic_blocks
* sizeof (rtx
));
363 basic_block_end
= (rtx
*) oballoc (n_basic_blocks
* sizeof (rtx
));
364 basic_block_drops_in
= (char *) alloca (n_basic_blocks
);
365 basic_block_loop_depth
= (short *) alloca (n_basic_blocks
* sizeof (short));
367 = (short *) alloca ((max_uid_for_flow
+ 1) * sizeof (short));
368 uid_volatile
= (char *) alloca (max_uid_for_flow
+ 1);
369 bzero (uid_volatile
, max_uid_for_flow
+ 1);
371 find_basic_blocks (f
, nonlocal_label_list
);
372 life_analysis (f
, nregs
);
374 dump_flow_info (file
);
376 basic_block_drops_in
= 0;
377 uid_block_number
= 0;
378 basic_block_loop_depth
= 0;
381 /* Find all basic blocks of the function whose first insn is F.
382 Store the correct data in the tables that describe the basic blocks,
383 set up the chains of references for each CODE_LABEL, and
384 delete any entire basic blocks that cannot be reached.
386 NONLOCAL_LABEL_LIST is the same local variable from flow_analysis. */
389 find_basic_blocks (f
, nonlocal_label_list
)
390 rtx f
, nonlocal_label_list
;
394 register char *block_live
= (char *) alloca (n_basic_blocks
);
395 register char *block_marked
= (char *) alloca (n_basic_blocks
);
396 /* List of label_refs to all labels whose addresses are taken
398 rtx label_value_list
= 0;
400 block_live_static
= block_live
;
401 bzero (block_live
, n_basic_blocks
);
402 bzero (block_marked
, n_basic_blocks
);
404 /* Initialize with just block 0 reachable and no blocks marked. */
405 if (n_basic_blocks
> 0)
408 /* Initialize the ref chain of each label to 0. */
409 /* Record where all the blocks start and end and their depth in loops. */
410 /* For each insn, record the block it is in. */
411 /* Also mark as reachable any blocks headed by labels that
412 must not be deleted. */
415 register RTX_CODE prev_code
= JUMP_INSN
;
416 register RTX_CODE code
;
419 for (insn
= f
, i
= -1; insn
; insn
= NEXT_INSN (insn
))
421 code
= GET_CODE (insn
);
424 if (NOTE_LINE_NUMBER (insn
) == NOTE_INSN_LOOP_BEG
)
426 else if (NOTE_LINE_NUMBER (insn
) == NOTE_INSN_LOOP_END
)
429 /* A basic block starts at label, or after something that can jump. */
430 else if (code
== CODE_LABEL
431 || (GET_RTX_CLASS (code
) == 'i'
432 && (prev_code
== JUMP_INSN
433 || (prev_code
== CALL_INSN
434 && nonlocal_label_list
!= 0)
435 || prev_code
== BARRIER
)))
437 basic_block_head
[++i
] = insn
;
438 basic_block_end
[i
] = insn
;
439 basic_block_loop_depth
[i
] = depth
;
440 if (code
== CODE_LABEL
)
442 LABEL_REFS (insn
) = insn
;
443 /* Any label that cannot be deleted
444 is considered to start a reachable block. */
445 if (LABEL_PRESERVE_P (insn
))
449 else if (GET_RTX_CLASS (code
) == 'i')
451 basic_block_end
[i
] = insn
;
452 basic_block_loop_depth
[i
] = depth
;
455 /* Make a list of all labels referred to other than by jumps. */
456 if (code
== INSN
|| code
== CALL_INSN
)
458 rtx note
= find_reg_note (insn
, REG_LABEL
, NULL_RTX
);
460 label_value_list
= gen_rtx (EXPR_LIST
, VOIDmode
, XEXP (note
, 0),
464 BLOCK_NUM (insn
) = i
;
466 /* Don't separate a CALL_INSN from following CLOBBER insns. This is
467 a kludge that will go away when each CALL_INSN records its
471 && ! (prev_code
== CALL_INSN
&& code
== INSN
472 && GET_CODE (PATTERN (insn
)) == CLOBBER
))
475 if (i
+ 1 != n_basic_blocks
)
479 /* Don't delete the labels that are referenced by non-jump instructions. */
482 for (x
= label_value_list
; x
; x
= XEXP (x
, 1))
483 block_live
[BLOCK_NUM (XEXP (x
, 0))] = 1;
486 /* Record which basic blocks control can drop in to. */
490 for (i
= 0; i
< n_basic_blocks
; i
++)
492 register rtx insn
= PREV_INSN (basic_block_head
[i
]);
493 /* TEMP1 is used to avoid a bug in Sequent's compiler. */
495 while (insn
&& GET_CODE (insn
) == NOTE
)
496 insn
= PREV_INSN (insn
);
497 temp1
= insn
&& GET_CODE (insn
) != BARRIER
;
498 basic_block_drops_in
[i
] = temp1
;
502 /* Now find which basic blocks can actually be reached
503 and put all jump insns' LABEL_REFS onto the ref-chains
504 of their target labels. */
506 if (n_basic_blocks
> 0)
508 int something_marked
= 1;
510 /* Find all indirect jump insns and mark them as possibly jumping
511 to all the labels whose addresses are explicitly used.
512 This is because, when there are computed gotos,
513 we can't tell which labels they jump to, of all the possibilities. */
515 for (insn
= f
; insn
; insn
= NEXT_INSN (insn
))
516 if (GET_CODE (insn
) == JUMP_INSN
517 && GET_CODE (PATTERN (insn
)) == SET
518 && SET_DEST (PATTERN (insn
)) == pc_rtx
519 && (GET_CODE (SET_SRC (PATTERN (insn
))) == REG
520 || GET_CODE (SET_SRC (PATTERN (insn
))) == MEM
))
523 for (x
= label_value_list
; x
; x
= XEXP (x
, 1))
524 mark_label_ref (gen_rtx (LABEL_REF
, VOIDmode
, XEXP (x
, 0)),
526 for (x
= forced_labels
; x
; x
= XEXP (x
, 1))
527 mark_label_ref (gen_rtx (LABEL_REF
, VOIDmode
, XEXP (x
, 0)),
531 /* Find all call insns and mark them as possibly jumping
532 to all the nonlocal goto handler labels. */
534 for (insn
= f
; insn
; insn
= NEXT_INSN (insn
))
535 if (GET_CODE (insn
) == CALL_INSN
)
538 for (x
= nonlocal_label_list
; x
; x
= XEXP (x
, 1))
539 mark_label_ref (gen_rtx (LABEL_REF
, VOIDmode
, XEXP (x
, 0)),
541 /* ??? This could be made smarter:
542 in some cases it's possible to tell that certain
543 calls will not do a nonlocal goto.
545 For example, if the nested functions that do the
546 nonlocal gotos do not have their addresses taken, then
547 only calls to those functions or to other nested
548 functions that use them could possibly do nonlocal
552 /* Pass over all blocks, marking each block that is reachable
553 and has not yet been marked.
554 Keep doing this until, in one pass, no blocks have been marked.
555 Then blocks_live and blocks_marked are identical and correct.
556 In addition, all jumps actually reachable have been marked. */
558 while (something_marked
)
560 something_marked
= 0;
561 for (i
= 0; i
< n_basic_blocks
; i
++)
562 if (block_live
[i
] && !block_marked
[i
])
565 something_marked
= 1;
566 if (i
+ 1 < n_basic_blocks
&& basic_block_drops_in
[i
+ 1])
567 block_live
[i
+ 1] = 1;
568 insn
= basic_block_end
[i
];
569 if (GET_CODE (insn
) == JUMP_INSN
)
570 mark_label_ref (PATTERN (insn
), insn
, 0);
574 /* Now delete the code for any basic blocks that can't be reached.
575 They can occur because jump_optimize does not recognize
576 unreachable loops as unreachable. */
578 for (i
= 0; i
< n_basic_blocks
; i
++)
581 insn
= basic_block_head
[i
];
584 if (GET_CODE (insn
) == BARRIER
)
586 if (GET_CODE (insn
) != NOTE
)
588 PUT_CODE (insn
, NOTE
);
589 NOTE_LINE_NUMBER (insn
) = NOTE_INSN_DELETED
;
590 NOTE_SOURCE_FILE (insn
) = 0;
592 if (insn
== basic_block_end
[i
])
594 /* BARRIERs are between basic blocks, not part of one.
595 Delete a BARRIER if the preceding jump is deleted.
596 We cannot alter a BARRIER into a NOTE
597 because it is too short; but we can really delete
598 it because it is not part of a basic block. */
599 if (NEXT_INSN (insn
) != 0
600 && GET_CODE (NEXT_INSN (insn
)) == BARRIER
)
601 delete_insn (NEXT_INSN (insn
));
604 insn
= NEXT_INSN (insn
);
606 /* Each time we delete some basic blocks,
607 see if there is a jump around them that is
608 being turned into a no-op. If so, delete it. */
610 if (block_live
[i
- 1])
613 for (j
= i
; j
< n_basic_blocks
; j
++)
617 insn
= basic_block_end
[i
- 1];
618 if (GET_CODE (insn
) == JUMP_INSN
619 /* An unconditional jump is the only possibility
620 we must check for, since a conditional one
621 would make these blocks live. */
622 && simplejump_p (insn
)
623 && (label
= XEXP (SET_SRC (PATTERN (insn
)), 0), 1)
624 && INSN_UID (label
) != 0
625 && BLOCK_NUM (label
) == j
)
627 PUT_CODE (insn
, NOTE
);
628 NOTE_LINE_NUMBER (insn
) = NOTE_INSN_DELETED
;
629 NOTE_SOURCE_FILE (insn
) = 0;
630 if (GET_CODE (NEXT_INSN (insn
)) != BARRIER
)
632 delete_insn (NEXT_INSN (insn
));
641 /* Check expression X for label references;
642 if one is found, add INSN to the label's chain of references.
644 CHECKDUP means check for and avoid creating duplicate references
645 from the same insn. Such duplicates do no serious harm but
646 can slow life analysis. CHECKDUP is set only when duplicates
650 mark_label_ref (x
, insn
, checkdup
)
654 register RTX_CODE code
;
658 /* We can be called with NULL when scanning label_value_list. */
663 if (code
== LABEL_REF
)
665 register rtx label
= XEXP (x
, 0);
667 if (GET_CODE (label
) != CODE_LABEL
)
669 /* If the label was never emitted, this insn is junk,
670 but avoid a crash trying to refer to BLOCK_NUM (label).
671 This can happen as a result of a syntax error
672 and a diagnostic has already been printed. */
673 if (INSN_UID (label
) == 0)
675 CONTAINING_INSN (x
) = insn
;
676 /* if CHECKDUP is set, check for duplicate ref from same insn
679 for (y
= LABEL_REFS (label
); y
!= label
; y
= LABEL_NEXTREF (y
))
680 if (CONTAINING_INSN (y
) == insn
)
682 LABEL_NEXTREF (x
) = LABEL_REFS (label
);
683 LABEL_REFS (label
) = x
;
684 block_live_static
[BLOCK_NUM (label
)] = 1;
688 fmt
= GET_RTX_FORMAT (code
);
689 for (i
= GET_RTX_LENGTH (code
) - 1; i
>= 0; i
--)
692 mark_label_ref (XEXP (x
, i
), insn
, 0);
696 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
697 mark_label_ref (XVECEXP (x
, i
, j
), insn
, 1);
702 /* Determine which registers are live at the start of each
703 basic block of the function whose first insn is F.
704 NREGS is the number of registers used in F.
705 We allocate the vector basic_block_live_at_start
706 and the regsets that it points to, and fill them with the data.
707 regset_size and regset_bytes are also set here. */
710 life_analysis (f
, nregs
)
717 /* For each basic block, a bitmask of regs
718 live on exit from the block. */
719 regset
*basic_block_live_at_end
;
720 /* For each basic block, a bitmask of regs
721 live on entry to a successor-block of this block.
722 If this does not match basic_block_live_at_end,
723 that must be updated, and the block must be rescanned. */
724 regset
*basic_block_new_live_at_end
;
725 /* For each basic block, a bitmask of regs
726 whose liveness at the end of the basic block
727 can make a difference in which regs are live on entry to the block.
728 These are the regs that are set within the basic block,
729 possibly excluding those that are used after they are set. */
730 regset
*basic_block_significant
;
734 struct obstack flow_obstack
;
736 gcc_obstack_init (&flow_obstack
);
740 bzero (regs_ever_live
, sizeof regs_ever_live
);
742 /* Allocate and zero out many data structures
743 that will record the data from lifetime analysis. */
745 allocate_for_life_analysis ();
747 reg_next_use
= (rtx
*) alloca (nregs
* sizeof (rtx
));
748 bzero (reg_next_use
, nregs
* sizeof (rtx
));
750 /* Set up several regset-vectors used internally within this function.
751 Their meanings are documented above, with their declarations. */
753 basic_block_live_at_end
= (regset
*) alloca (n_basic_blocks
* sizeof (regset
));
754 /* Don't use alloca since that leads to a crash rather than an error message
755 if there isn't enough space.
756 Don't use oballoc since we may need to allocate other things during
757 this function on the temporary obstack. */
758 tem
= (regset
) obstack_alloc (&flow_obstack
, n_basic_blocks
* regset_bytes
);
759 bzero (tem
, n_basic_blocks
* regset_bytes
);
760 init_regset_vector (basic_block_live_at_end
, tem
, n_basic_blocks
, regset_bytes
);
762 basic_block_new_live_at_end
= (regset
*) alloca (n_basic_blocks
* sizeof (regset
));
763 tem
= (regset
) obstack_alloc (&flow_obstack
, n_basic_blocks
* regset_bytes
);
764 bzero (tem
, n_basic_blocks
* regset_bytes
);
765 init_regset_vector (basic_block_new_live_at_end
, tem
, n_basic_blocks
, regset_bytes
);
767 basic_block_significant
= (regset
*) alloca (n_basic_blocks
* sizeof (regset
));
768 tem
= (regset
) obstack_alloc (&flow_obstack
, n_basic_blocks
* regset_bytes
);
769 bzero (tem
, n_basic_blocks
* regset_bytes
);
770 init_regset_vector (basic_block_significant
, tem
, n_basic_blocks
, regset_bytes
);
772 /* Record which insns refer to any volatile memory
773 or for any reason can't be deleted just because they are dead stores.
774 Also, delete any insns that copy a register to itself. */
776 for (insn
= f
; insn
; insn
= NEXT_INSN (insn
))
778 enum rtx_code code1
= GET_CODE (insn
);
779 if (code1
== CALL_INSN
)
780 INSN_VOLATILE (insn
) = 1;
781 else if (code1
== INSN
|| code1
== JUMP_INSN
)
783 /* Delete (in effect) any obvious no-op moves. */
784 if (GET_CODE (PATTERN (insn
)) == SET
785 && GET_CODE (SET_DEST (PATTERN (insn
))) == REG
786 && GET_CODE (SET_SRC (PATTERN (insn
))) == REG
787 && REGNO (SET_DEST (PATTERN (insn
))) ==
788 REGNO (SET_SRC (PATTERN (insn
)))
789 /* Insns carrying these notes are useful later on. */
790 && ! find_reg_note (insn
, REG_EQUAL
, NULL_RTX
))
792 PUT_CODE (insn
, NOTE
);
793 NOTE_LINE_NUMBER (insn
) = NOTE_INSN_DELETED
;
794 NOTE_SOURCE_FILE (insn
) = 0;
796 else if (GET_CODE (PATTERN (insn
)) == PARALLEL
)
798 /* If nothing but SETs of registers to themselves,
799 this insn can also be deleted. */
800 for (i
= 0; i
< XVECLEN (PATTERN (insn
), 0); i
++)
802 rtx tem
= XVECEXP (PATTERN (insn
), 0, i
);
804 if (GET_CODE (tem
) == USE
805 || GET_CODE (tem
) == CLOBBER
)
808 if (GET_CODE (tem
) != SET
809 || GET_CODE (SET_DEST (tem
)) != REG
810 || GET_CODE (SET_SRC (tem
)) != REG
811 || REGNO (SET_DEST (tem
)) != REGNO (SET_SRC (tem
)))
815 if (i
== XVECLEN (PATTERN (insn
), 0)
816 /* Insns carrying these notes are useful later on. */
817 && ! find_reg_note (insn
, REG_EQUAL
, NULL_RTX
))
819 PUT_CODE (insn
, NOTE
);
820 NOTE_LINE_NUMBER (insn
) = NOTE_INSN_DELETED
;
821 NOTE_SOURCE_FILE (insn
) = 0;
824 INSN_VOLATILE (insn
) = volatile_refs_p (PATTERN (insn
));
826 else if (GET_CODE (PATTERN (insn
)) != USE
)
827 INSN_VOLATILE (insn
) = volatile_refs_p (PATTERN (insn
));
828 /* A SET that makes space on the stack cannot be dead.
829 (Such SETs occur only for allocating variable-size data,
830 so they will always have a PLUS or MINUS according to the
831 direction of stack growth.)
832 Even if this function never uses this stack pointer value,
833 signal handlers do! */
834 else if (code1
== INSN
&& GET_CODE (PATTERN (insn
)) == SET
835 && SET_DEST (PATTERN (insn
)) == stack_pointer_rtx
836 #ifdef STACK_GROWS_DOWNWARD
837 && GET_CODE (SET_SRC (PATTERN (insn
))) == MINUS
839 && GET_CODE (SET_SRC (PATTERN (insn
))) == PLUS
841 && XEXP (SET_SRC (PATTERN (insn
)), 0) == stack_pointer_rtx
)
842 INSN_VOLATILE (insn
) = 1;
846 if (n_basic_blocks
> 0)
847 #ifdef EXIT_IGNORE_STACK
848 if (! EXIT_IGNORE_STACK
849 || (! FRAME_POINTER_REQUIRED
&& flag_omit_frame_pointer
))
852 /* If exiting needs the right stack value,
853 consider the stack pointer live at the end of the function. */
854 basic_block_live_at_end
[n_basic_blocks
- 1]
855 [STACK_POINTER_REGNUM
/ REGSET_ELT_BITS
]
856 |= 1 << (STACK_POINTER_REGNUM
% REGSET_ELT_BITS
);
857 basic_block_new_live_at_end
[n_basic_blocks
- 1]
858 [STACK_POINTER_REGNUM
/ REGSET_ELT_BITS
]
859 |= 1 << (STACK_POINTER_REGNUM
% REGSET_ELT_BITS
);
862 /* Mark all global registers as being live at the end of the function
863 since they may be referenced by our caller. */
865 if (n_basic_blocks
> 0)
866 for (i
= 0; i
< FIRST_PSEUDO_REGISTER
; i
++)
869 basic_block_live_at_end
[n_basic_blocks
- 1]
870 [i
/ REGSET_ELT_BITS
] |= 1 << (i
% REGSET_ELT_BITS
);
871 basic_block_new_live_at_end
[n_basic_blocks
- 1]
872 [i
/ REGSET_ELT_BITS
] |= 1 << (i
% REGSET_ELT_BITS
);
875 /* Propagate life info through the basic blocks
876 around the graph of basic blocks.
878 This is a relaxation process: each time a new register
879 is live at the end of the basic block, we must scan the block
880 to determine which registers are, as a consequence, live at the beginning
881 of that block. These registers must then be marked live at the ends
882 of all the blocks that can transfer control to that block.
883 The process continues until it reaches a fixed point. */
890 for (i
= n_basic_blocks
- 1; i
>= 0; i
--)
892 int consider
= first_pass
;
893 int must_rescan
= first_pass
;
898 /* Set CONSIDER if this block needs thinking about at all
899 (that is, if the regs live now at the end of it
900 are not the same as were live at the end of it when
901 we last thought about it).
902 Set must_rescan if it needs to be thought about
903 instruction by instruction (that is, if any additional
904 reg that is live at the end now but was not live there before
905 is one of the significant regs of this basic block). */
907 for (j
= 0; j
< regset_size
; j
++)
909 register REGSET_ELT_TYPE x
910 = (basic_block_new_live_at_end
[i
][j
]
911 & ~basic_block_live_at_end
[i
][j
]);
914 if (x
& basic_block_significant
[i
][j
])
926 /* The live_at_start of this block may be changing,
927 so another pass will be required after this one. */
932 /* No complete rescan needed;
933 just record those variables newly known live at end
934 as live at start as well. */
935 for (j
= 0; j
< regset_size
; j
++)
937 register REGSET_ELT_TYPE x
938 = (basic_block_new_live_at_end
[i
][j
]
939 & ~basic_block_live_at_end
[i
][j
]);
940 basic_block_live_at_start
[i
][j
] |= x
;
941 basic_block_live_at_end
[i
][j
] |= x
;
946 /* Update the basic_block_live_at_start
947 by propagation backwards through the block. */
948 bcopy (basic_block_new_live_at_end
[i
],
949 basic_block_live_at_end
[i
], regset_bytes
);
950 bcopy (basic_block_live_at_end
[i
],
951 basic_block_live_at_start
[i
], regset_bytes
);
952 propagate_block (basic_block_live_at_start
[i
],
953 basic_block_head
[i
], basic_block_end
[i
], 0,
954 first_pass
? basic_block_significant
[i
]
960 register rtx jump
, head
;
961 /* Update the basic_block_new_live_at_end's of the block
962 that falls through into this one (if any). */
963 head
= basic_block_head
[i
];
964 jump
= PREV_INSN (head
);
965 if (basic_block_drops_in
[i
])
967 register int from_block
= BLOCK_NUM (jump
);
969 for (j
= 0; j
< regset_size
; j
++)
970 basic_block_new_live_at_end
[from_block
][j
]
971 |= basic_block_live_at_start
[i
][j
];
973 /* Update the basic_block_new_live_at_end's of
974 all the blocks that jump to this one. */
975 if (GET_CODE (head
) == CODE_LABEL
)
976 for (jump
= LABEL_REFS (head
);
978 jump
= LABEL_NEXTREF (jump
))
980 register int from_block
= BLOCK_NUM (CONTAINING_INSN (jump
));
982 for (j
= 0; j
< regset_size
; j
++)
983 basic_block_new_live_at_end
[from_block
][j
]
984 |= basic_block_live_at_start
[i
][j
];
994 /* The only pseudos that are live at the beginning of the function are
995 those that were not set anywhere in the function. local-alloc doesn't
996 know how to handle these correctly, so mark them as not local to any
999 if (n_basic_blocks
> 0)
1000 for (i
= FIRST_PSEUDO_REGISTER
; i
< max_regno
; i
++)
1001 if (basic_block_live_at_start
[0][i
/ REGSET_ELT_BITS
]
1002 & ((REGSET_ELT_TYPE
) 1 << (i
% REGSET_ELT_BITS
)))
1003 reg_basic_block
[i
] = REG_BLOCK_GLOBAL
;
1005 /* Now the life information is accurate.
1006 Make one more pass over each basic block
1007 to delete dead stores, create autoincrement addressing
1008 and record how many times each register is used, is set, or dies.
1010 To save time, we operate directly in basic_block_live_at_end[i],
1011 thus destroying it (in fact, converting it into a copy of
1012 basic_block_live_at_start[i]). This is ok now because
1013 basic_block_live_at_end[i] is no longer used past this point. */
1017 for (i
= 0; i
< n_basic_blocks
; i
++)
1019 propagate_block (basic_block_live_at_end
[i
],
1020 basic_block_head
[i
], basic_block_end
[i
], 1,
1028 /* Something live during a setjmp should not be put in a register
1029 on certain machines which restore regs from stack frames
1030 rather than from the jmpbuf.
1031 But we don't need to do this for the user's variables, since
1032 ANSI says only volatile variables need this. */
1033 #ifdef LONGJMP_RESTORE_FROM_STACK
1034 for (i
= FIRST_PSEUDO_REGISTER
; i
< nregs
; i
++)
1035 if (regs_live_at_setjmp
[i
/ REGSET_ELT_BITS
]
1036 & ((REGSET_ELT_TYPE
) 1 << (i
% REGSET_ELT_BITS
))
1037 && regno_reg_rtx
[i
] != 0 && ! REG_USERVAR_P (regno_reg_rtx
[i
]))
1039 reg_live_length
[i
] = -1;
1040 reg_basic_block
[i
] = -1;
1045 /* We have a problem with any pseudoreg that
1046 lives across the setjmp. ANSI says that if a
1047 user variable does not change in value
1048 between the setjmp and the longjmp, then the longjmp preserves it.
1049 This includes longjmp from a place where the pseudo appears dead.
1050 (In principle, the value still exists if it is in scope.)
1051 If the pseudo goes in a hard reg, some other value may occupy
1052 that hard reg where this pseudo is dead, thus clobbering the pseudo.
1053 Conclusion: such a pseudo must not go in a hard reg. */
1054 for (i
= FIRST_PSEUDO_REGISTER
; i
< nregs
; i
++)
1055 if ((regs_live_at_setjmp
[i
/ REGSET_ELT_BITS
]
1056 & ((REGSET_ELT_TYPE
) 1 << (i
% REGSET_ELT_BITS
)))
1057 && regno_reg_rtx
[i
] != 0)
1059 reg_live_length
[i
] = -1;
1060 reg_basic_block
[i
] = -1;
1063 obstack_free (&flow_obstack
, NULL_PTR
);
1066 /* Subroutines of life analysis. */
1068 /* Allocate the permanent data structures that represent the results
1069 of life analysis. Not static since used also for stupid life analysis. */
1072 allocate_for_life_analysis ()
1075 register regset tem
;
1077 regset_size
= ((max_regno
+ REGSET_ELT_BITS
- 1) / REGSET_ELT_BITS
);
1078 regset_bytes
= regset_size
* sizeof (*(regset
)0);
1080 reg_n_refs
= (int *) oballoc (max_regno
* sizeof (int));
1081 bzero (reg_n_refs
, max_regno
* sizeof (int));
1083 reg_n_sets
= (short *) oballoc (max_regno
* sizeof (short));
1084 bzero (reg_n_sets
, max_regno
* sizeof (short));
1086 reg_n_deaths
= (short *) oballoc (max_regno
* sizeof (short));
1087 bzero (reg_n_deaths
, max_regno
* sizeof (short));
1089 reg_live_length
= (int *) oballoc (max_regno
* sizeof (int));
1090 bzero (reg_live_length
, max_regno
* sizeof (int));
1092 reg_n_calls_crossed
= (int *) oballoc (max_regno
* sizeof (int));
1093 bzero (reg_n_calls_crossed
, max_regno
* sizeof (int));
1095 reg_basic_block
= (short *) oballoc (max_regno
* sizeof (short));
1096 for (i
= 0; i
< max_regno
; i
++)
1097 reg_basic_block
[i
] = REG_BLOCK_UNKNOWN
;
1099 basic_block_live_at_start
= (regset
*) oballoc (n_basic_blocks
* sizeof (regset
));
1100 tem
= (regset
) oballoc (n_basic_blocks
* regset_bytes
);
1101 bzero (tem
, n_basic_blocks
* regset_bytes
);
1102 init_regset_vector (basic_block_live_at_start
, tem
, n_basic_blocks
, regset_bytes
);
1104 regs_live_at_setjmp
= (regset
) oballoc (regset_bytes
);
1105 bzero (regs_live_at_setjmp
, regset_bytes
);
1108 /* Make each element of VECTOR point at a regset,
1109 taking the space for all those regsets from SPACE.
1110 SPACE is of type regset, but it is really as long as NELTS regsets.
1111 BYTES_PER_ELT is the number of bytes in one regset. */
1114 init_regset_vector (vector
, space
, nelts
, bytes_per_elt
)
1121 register regset p
= space
;
1123 for (i
= 0; i
< nelts
; i
++)
1126 p
+= bytes_per_elt
/ sizeof (*p
);
1130 /* Compute the registers live at the beginning of a basic block
1131 from those live at the end.
1133 When called, OLD contains those live at the end.
1134 On return, it contains those live at the beginning.
1135 FIRST and LAST are the first and last insns of the basic block.
1137 FINAL is nonzero if we are doing the final pass which is not
1138 for computing the life info (since that has already been done)
1139 but for acting on it. On this pass, we delete dead stores,
1140 set up the logical links and dead-variables lists of instructions,
1141 and merge instructions for autoincrement and autodecrement addresses.
1143 SIGNIFICANT is nonzero only the first time for each basic block.
1144 If it is nonzero, it points to a regset in which we store
1145 a 1 for each register that is set within the block.
1147 BNUM is the number of the basic block. */
1150 propagate_block (old
, first
, last
, final
, significant
, bnum
)
1151 register regset old
;
1163 /* The following variables are used only if FINAL is nonzero. */
1164 /* This vector gets one element for each reg that has been live
1165 at any point in the basic block that has been scanned so far.
1166 SOMETIMES_MAX says how many elements are in use so far.
1167 In each element, OFFSET is the byte-number within a regset
1168 for the register described by the element, and BIT is a mask
1169 for that register's bit within the byte. */
1170 register struct sometimes
{ short offset
; short bit
; } *regs_sometimes_live
;
1171 int sometimes_max
= 0;
1172 /* This regset has 1 for each reg that we have seen live so far.
1173 It and REGS_SOMETIMES_LIVE are updated together. */
1176 /* The loop depth may change in the middle of a basic block. Since we
1177 scan from end to beginning, we start with the depth at the end of the
1178 current basic block, and adjust as we pass ends and starts of loops. */
1179 loop_depth
= basic_block_loop_depth
[bnum
];
1181 dead
= (regset
) alloca (regset_bytes
);
1182 live
= (regset
) alloca (regset_bytes
);
1187 /* Include any notes at the end of the block in the scan.
1188 This is in case the block ends with a call to setjmp. */
1190 while (NEXT_INSN (last
) != 0 && GET_CODE (NEXT_INSN (last
)) == NOTE
)
1192 /* Look for loop boundaries, we are going forward here. */
1193 last
= NEXT_INSN (last
);
1194 if (NOTE_LINE_NUMBER (last
) == NOTE_INSN_LOOP_BEG
)
1196 else if (NOTE_LINE_NUMBER (last
) == NOTE_INSN_LOOP_END
)
1202 register int i
, offset
;
1203 REGSET_ELT_TYPE bit
;
1206 maxlive
= (regset
) alloca (regset_bytes
);
1207 bcopy (old
, maxlive
, regset_bytes
);
1209 = (struct sometimes
*) alloca (max_regno
* sizeof (struct sometimes
));
1211 /* Process the regs live at the end of the block.
1212 Enter them in MAXLIVE and REGS_SOMETIMES_LIVE.
1213 Also mark them as not local to any one basic block. */
1215 for (offset
= 0, i
= 0; offset
< regset_size
; offset
++)
1216 for (bit
= 1; bit
; bit
<<= 1, i
++)
1220 if (old
[offset
] & bit
)
1222 reg_basic_block
[i
] = REG_BLOCK_GLOBAL
;
1223 regs_sometimes_live
[sometimes_max
].offset
= offset
;
1224 regs_sometimes_live
[sometimes_max
].bit
= i
% REGSET_ELT_BITS
;
1230 /* Scan the block an insn at a time from end to beginning. */
1232 for (insn
= last
; ; insn
= prev
)
1234 prev
= PREV_INSN (insn
);
1236 /* Look for loop boundaries, remembering that we are going backwards. */
1237 if (GET_CODE (insn
) == NOTE
1238 && NOTE_LINE_NUMBER (insn
) == NOTE_INSN_LOOP_END
)
1240 else if (GET_CODE (insn
) == NOTE
1241 && NOTE_LINE_NUMBER (insn
) == NOTE_INSN_LOOP_BEG
)
1244 /* If we have LOOP_DEPTH == 0, there has been a bookkeeping error.
1245 Abort now rather than setting register status incorrectly. */
1246 if (loop_depth
== 0)
1249 /* If this is a call to `setjmp' et al,
1250 warn if any non-volatile datum is live. */
1252 if (final
&& GET_CODE (insn
) == NOTE
1253 && NOTE_LINE_NUMBER (insn
) == NOTE_INSN_SETJMP
)
1256 for (i
= 0; i
< regset_size
; i
++)
1257 regs_live_at_setjmp
[i
] |= old
[i
];
1260 /* Update the life-status of regs for this insn.
1261 First DEAD gets which regs are set in this insn
1262 then LIVE gets which regs are used in this insn.
1263 Then the regs live before the insn
1264 are those live after, with DEAD regs turned off,
1265 and then LIVE regs turned on. */
1267 if (GET_RTX_CLASS (GET_CODE (insn
)) == 'i')
1270 rtx note
= find_reg_note (insn
, REG_RETVAL
, NULL_RTX
);
1272 = (insn_dead_p (PATTERN (insn
), old
, 0)
1273 /* Don't delete something that refers to volatile storage! */
1274 && ! INSN_VOLATILE (insn
));
1276 = (insn_is_dead
&& note
!= 0
1277 && libcall_dead_p (PATTERN (insn
), old
, note
, insn
));
1279 /* If an instruction consists of just dead store(s) on final pass,
1280 "delete" it by turning it into a NOTE of type NOTE_INSN_DELETED.
1281 We could really delete it with delete_insn, but that
1282 can cause trouble for first or last insn in a basic block. */
1283 if (final
&& insn_is_dead
)
1285 PUT_CODE (insn
, NOTE
);
1286 NOTE_LINE_NUMBER (insn
) = NOTE_INSN_DELETED
;
1287 NOTE_SOURCE_FILE (insn
) = 0;
1289 /* CC0 is now known to be dead. Either this insn used it,
1290 in which case it doesn't anymore, or clobbered it,
1291 so the next insn can't use it. */
1294 /* If this insn is copying the return value from a library call,
1295 delete the entire library call. */
1296 if (libcall_is_dead
)
1298 rtx first
= XEXP (note
, 0);
1300 while (INSN_DELETED_P (first
))
1301 first
= NEXT_INSN (first
);
1306 NOTE_LINE_NUMBER (p
) = NOTE_INSN_DELETED
;
1307 NOTE_SOURCE_FILE (p
) = 0;
1313 for (i
= 0; i
< regset_size
; i
++)
1315 dead
[i
] = 0; /* Faster than bzero here */
1316 live
[i
] = 0; /* since regset_size is usually small */
1319 /* See if this is an increment or decrement that can be
1320 merged into a following memory address. */
1323 register rtx x
= PATTERN (insn
);
1324 /* Does this instruction increment or decrement a register? */
1325 if (final
&& GET_CODE (x
) == SET
1326 && GET_CODE (SET_DEST (x
)) == REG
1327 && (GET_CODE (SET_SRC (x
)) == PLUS
1328 || GET_CODE (SET_SRC (x
)) == MINUS
)
1329 && XEXP (SET_SRC (x
), 0) == SET_DEST (x
)
1330 && GET_CODE (XEXP (SET_SRC (x
), 1)) == CONST_INT
1331 /* Ok, look for a following memory ref we can combine with.
1332 If one is found, change the memory ref to a PRE_INC
1333 or PRE_DEC, cancel this insn, and return 1.
1334 Return 0 if nothing has been done. */
1335 && try_pre_increment_1 (insn
))
1338 #endif /* AUTO_INC_DEC */
1340 /* If this is not the final pass, and this insn is copying the
1341 value of a library call and it's dead, don't scan the
1342 insns that perform the library call, so that the call's
1343 arguments are not marked live. */
1344 if (libcall_is_dead
)
1346 /* Mark the dest reg as `significant'. */
1347 mark_set_regs (old
, dead
, PATTERN (insn
), NULL_RTX
, significant
);
1349 insn
= XEXP (note
, 0);
1350 prev
= PREV_INSN (insn
);
1352 else if (GET_CODE (PATTERN (insn
)) == SET
1353 && SET_DEST (PATTERN (insn
)) == stack_pointer_rtx
1354 && GET_CODE (SET_SRC (PATTERN (insn
))) == PLUS
1355 && XEXP (SET_SRC (PATTERN (insn
)), 0) == stack_pointer_rtx
1356 && GET_CODE (XEXP (SET_SRC (PATTERN (insn
)), 1)) == CONST_INT
)
1357 /* We have an insn to pop a constant amount off the stack.
1358 (Such insns use PLUS regardless of the direction of the stack,
1359 and any insn to adjust the stack by a constant is always a pop.)
1360 These insns, if not dead stores, have no effect on life. */
1364 /* LIVE gets the regs used in INSN;
1365 DEAD gets those set by it. Dead insns don't make anything
1368 mark_set_regs (old
, dead
, PATTERN (insn
),
1369 final
? insn
: NULL_RTX
, significant
);
1371 /* If an insn doesn't use CC0, it becomes dead since we
1372 assume that every insn clobbers it. So show it dead here;
1373 mark_used_regs will set it live if it is referenced. */
1377 mark_used_regs (old
, live
, PATTERN (insn
), final
, insn
);
1379 /* Sometimes we may have inserted something before INSN (such as
1380 a move) when we make an auto-inc. So ensure we will scan
1383 prev
= PREV_INSN (insn
);
1386 if (! insn_is_dead
&& GET_CODE (insn
) == CALL_INSN
)
1390 /* Each call clobbers all call-clobbered regs that are not
1391 global. Note that the function-value reg is a
1392 call-clobbered reg, and mark_set_regs has already had
1393 a chance to handle it. */
1395 for (i
= 0; i
< FIRST_PSEUDO_REGISTER
; i
++)
1396 if (call_used_regs
[i
] && ! global_regs
[i
])
1397 dead
[i
/ REGSET_ELT_BITS
]
1398 |= ((REGSET_ELT_TYPE
) 1 << (i
% REGSET_ELT_BITS
));
1400 /* The stack ptr is used (honorarily) by a CALL insn. */
1401 live
[STACK_POINTER_REGNUM
/ REGSET_ELT_BITS
]
1402 |= ((REGSET_ELT_TYPE
) 1
1403 << (STACK_POINTER_REGNUM
% REGSET_ELT_BITS
));
1405 /* Calls may also reference any of the global registers,
1406 so they are made live. */
1408 for (i
= 0; i
< FIRST_PSEUDO_REGISTER
; i
++)
1410 live
[i
/ REGSET_ELT_BITS
]
1411 |= ((REGSET_ELT_TYPE
) 1 << (i
% REGSET_ELT_BITS
));
1413 /* Calls also clobber memory. */
1417 /* Update OLD for the registers used or set. */
1418 for (i
= 0; i
< regset_size
; i
++)
1424 if (GET_CODE (insn
) == CALL_INSN
&& final
)
1426 /* Any regs live at the time of a call instruction
1427 must not go in a register clobbered by calls.
1428 Find all regs now live and record this for them. */
1430 register struct sometimes
*p
= regs_sometimes_live
;
1432 for (i
= 0; i
< sometimes_max
; i
++, p
++)
1433 if (old
[p
->offset
] & (1 << p
->bit
))
1434 reg_n_calls_crossed
[p
->offset
* REGSET_ELT_BITS
+ p
->bit
]+= 1;
1438 /* On final pass, add any additional sometimes-live regs
1439 into MAXLIVE and REGS_SOMETIMES_LIVE.
1440 Also update counts of how many insns each reg is live at. */
1444 for (i
= 0; i
< regset_size
; i
++)
1446 register REGSET_ELT_TYPE diff
= live
[i
] & ~maxlive
[i
];
1452 for (regno
= 0; diff
&& regno
< REGSET_ELT_BITS
; regno
++)
1453 if (diff
& ((REGSET_ELT_TYPE
) 1 << regno
))
1455 regs_sometimes_live
[sometimes_max
].offset
= i
;
1456 regs_sometimes_live
[sometimes_max
].bit
= regno
;
1457 diff
&= ~ ((REGSET_ELT_TYPE
) 1 << regno
);
1464 register struct sometimes
*p
= regs_sometimes_live
;
1465 for (i
= 0; i
< sometimes_max
; i
++, p
++)
1467 if (old
[p
->offset
] & ((REGSET_ELT_TYPE
) 1 << p
->bit
))
1468 reg_live_length
[p
->offset
* REGSET_ELT_BITS
+ p
->bit
]++;
1478 if (num_scratch
> max_scratch
)
1479 max_scratch
= num_scratch
;
1482 /* Return 1 if X (the body of an insn, or part of it) is just dead stores
1483 (SET expressions whose destinations are registers dead after the insn).
1484 NEEDED is the regset that says which regs are alive after the insn.
1486 Unless CALL_OK is non-zero, an insn is needed if it contains a CALL. */
1489 insn_dead_p (x
, needed
, call_ok
)
1494 register RTX_CODE code
= GET_CODE (x
);
1495 /* If setting something that's a reg or part of one,
1496 see if that register's altered value will be live. */
1500 register rtx r
= SET_DEST (x
);
1501 /* A SET that is a subroutine call cannot be dead. */
1502 if (! call_ok
&& GET_CODE (SET_SRC (x
)) == CALL
)
1506 if (GET_CODE (r
) == CC0
)
1510 if (GET_CODE (r
) == MEM
&& last_mem_set
&& ! MEM_VOLATILE_P (r
)
1511 && rtx_equal_p (r
, last_mem_set
))
1514 while (GET_CODE (r
) == SUBREG
1515 || GET_CODE (r
) == STRICT_LOW_PART
1516 || GET_CODE (r
) == ZERO_EXTRACT
1517 || GET_CODE (r
) == SIGN_EXTRACT
)
1520 if (GET_CODE (r
) == REG
)
1522 register int regno
= REGNO (r
);
1523 register int offset
= regno
/ REGSET_ELT_BITS
;
1524 register REGSET_ELT_TYPE bit
1525 = (REGSET_ELT_TYPE
) 1 << (regno
% REGSET_ELT_BITS
);
1527 /* Don't delete insns to set global regs. */
1528 if ((regno
< FIRST_PSEUDO_REGISTER
&& global_regs
[regno
])
1529 /* Make sure insns to set frame pointer aren't deleted. */
1530 || regno
== FRAME_POINTER_REGNUM
1531 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
1532 /* Make sure insns to set arg pointer are never deleted
1533 (if the arg pointer isn't fixed, there will be a USE for
1534 it, so we can treat it normally). */
1535 || (regno
== ARG_POINTER_REGNUM
&& fixed_regs
[regno
])
1537 || (needed
[offset
] & bit
) != 0)
1540 /* If this is a hard register, verify that subsequent words are
1542 if (regno
< FIRST_PSEUDO_REGISTER
)
1544 int n
= HARD_REGNO_NREGS (regno
, GET_MODE (r
));
1547 if ((needed
[(regno
+ n
) / REGSET_ELT_BITS
]
1548 & ((REGSET_ELT_TYPE
) 1
1549 << ((regno
+ n
) % REGSET_ELT_BITS
))) != 0)
1556 /* If performing several activities,
1557 insn is dead if each activity is individually dead.
1558 Also, CLOBBERs and USEs can be ignored; a CLOBBER or USE
1559 that's inside a PARALLEL doesn't make the insn worth keeping. */
1560 else if (code
== PARALLEL
)
1562 register int i
= XVECLEN (x
, 0);
1563 for (i
--; i
>= 0; i
--)
1565 rtx elt
= XVECEXP (x
, 0, i
);
1566 if (!insn_dead_p (elt
, needed
, call_ok
)
1567 && GET_CODE (elt
) != CLOBBER
1568 && GET_CODE (elt
) != USE
)
1573 /* We do not check CLOBBER or USE here.
1574 An insn consisting of just a CLOBBER or just a USE
1575 should not be deleted. */
1579 /* If X is the pattern of the last insn in a libcall, and assuming X is dead,
1580 return 1 if the entire library call is dead.
1581 This is true if X copies a register (hard or pseudo)
1582 and if the hard return reg of the call insn is dead.
1583 (The caller should have tested the destination of X already for death.)
1585 If this insn doesn't just copy a register, then we don't
1586 have an ordinary libcall. In that case, cse could not have
1587 managed to substitute the source for the dest later on,
1588 so we can assume the libcall is dead.
1590 NEEDED is the bit vector of pseudoregs live before this insn.
1591 NOTE is the REG_RETVAL note of the insn. INSN is the insn itself. */
1594 libcall_dead_p (x
, needed
, note
, insn
)
1600 register RTX_CODE code
= GET_CODE (x
);
1604 register rtx r
= SET_SRC (x
);
1605 if (GET_CODE (r
) == REG
)
1607 rtx call
= XEXP (note
, 0);
1610 /* Find the call insn. */
1611 while (call
!= insn
&& GET_CODE (call
) != CALL_INSN
)
1612 call
= NEXT_INSN (call
);
1614 /* If there is none, do nothing special,
1615 since ordinary death handling can understand these insns. */
1619 /* See if the hard reg holding the value is dead.
1620 If this is a PARALLEL, find the call within it. */
1621 call
= PATTERN (call
);
1622 if (GET_CODE (call
) == PARALLEL
)
1624 for (i
= XVECLEN (call
, 0) - 1; i
>= 0; i
--)
1625 if (GET_CODE (XVECEXP (call
, 0, i
)) == SET
1626 && GET_CODE (SET_SRC (XVECEXP (call
, 0, i
))) == CALL
)
1632 call
= XVECEXP (call
, 0, i
);
1635 return insn_dead_p (call
, needed
, 1);
1641 /* Return 1 if register REGNO was used before it was set.
1642 In other words, if it is live at function entry.
1643 Don't count global regster variables, though. */
1646 regno_uninitialized (regno
)
1649 if (n_basic_blocks
== 0 || global_regs
[regno
])
1652 return (basic_block_live_at_start
[0][regno
/ REGSET_ELT_BITS
]
1653 & ((REGSET_ELT_TYPE
) 1 << (regno
% REGSET_ELT_BITS
)));
1656 /* 1 if register REGNO was alive at a place where `setjmp' was called
1657 and was set more than once or is an argument.
1658 Such regs may be clobbered by `longjmp'. */
1661 regno_clobbered_at_setjmp (regno
)
1664 if (n_basic_blocks
== 0)
1667 return ((reg_n_sets
[regno
] > 1
1668 || (basic_block_live_at_start
[0][regno
/ REGSET_ELT_BITS
]
1669 & ((REGSET_ELT_TYPE
) 1 << (regno
% REGSET_ELT_BITS
))))
1670 && (regs_live_at_setjmp
[regno
/ REGSET_ELT_BITS
]
1671 & ((REGSET_ELT_TYPE
) 1 << (regno
% REGSET_ELT_BITS
))));
1674 /* Process the registers that are set within X.
1675 Their bits are set to 1 in the regset DEAD,
1676 because they are dead prior to this insn.
1678 If INSN is nonzero, it is the insn being processed
1679 and the fact that it is nonzero implies this is the FINAL pass
1680 in propagate_block. In this case, various info about register
1681 usage is stored, LOG_LINKS fields of insns are set up. */
1683 static void mark_set_1 ();
1686 mark_set_regs (needed
, dead
, x
, insn
, significant
)
1693 register RTX_CODE code
= GET_CODE (x
);
1695 if (code
== SET
|| code
== CLOBBER
)
1696 mark_set_1 (needed
, dead
, x
, insn
, significant
);
1697 else if (code
== PARALLEL
)
1700 for (i
= XVECLEN (x
, 0) - 1; i
>= 0; i
--)
1702 code
= GET_CODE (XVECEXP (x
, 0, i
));
1703 if (code
== SET
|| code
== CLOBBER
)
1704 mark_set_1 (needed
, dead
, XVECEXP (x
, 0, i
), insn
, significant
);
1709 /* Process a single SET rtx, X. */
1712 mark_set_1 (needed
, dead
, x
, insn
, significant
)
1720 register rtx reg
= SET_DEST (x
);
1722 /* Modifying just one hardware register of a multi-reg value
1723 or just a byte field of a register
1724 does not mean the value from before this insn is now dead.
1725 But it does mean liveness of that register at the end of the block
1728 Within mark_set_1, however, we treat it as if the register is
1729 indeed modified. mark_used_regs will, however, also treat this
1730 register as being used. Thus, we treat these insns as setting a
1731 new value for the register as a function of its old value. This
1732 cases LOG_LINKS to be made appropriately and this will help combine. */
1734 while (GET_CODE (reg
) == SUBREG
|| GET_CODE (reg
) == ZERO_EXTRACT
1735 || GET_CODE (reg
) == SIGN_EXTRACT
1736 || GET_CODE (reg
) == STRICT_LOW_PART
)
1737 reg
= XEXP (reg
, 0);
1739 /* If we are writing into memory or into a register mentioned in the
1740 address of the last thing stored into memory, show we don't know
1741 what the last store was. If we are writing memory, save the address
1742 unless it is volatile. */
1743 if (GET_CODE (reg
) == MEM
1744 || (GET_CODE (reg
) == REG
1745 && last_mem_set
!= 0 && reg_overlap_mentioned_p (reg
, last_mem_set
)))
1748 if (GET_CODE (reg
) == MEM
&& ! side_effects_p (reg
)
1749 /* There are no REG_INC notes for SP, so we can't assume we'll see
1750 everything that invalidates it. To be safe, don't eliminate any
1751 stores though SP; none of them should be redundant anyway. */
1752 && ! reg_mentioned_p (stack_pointer_rtx
, reg
))
1755 if (GET_CODE (reg
) == REG
1756 && (regno
= REGNO (reg
), regno
!= FRAME_POINTER_REGNUM
)
1757 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
1758 && ! (regno
== ARG_POINTER_REGNUM
&& fixed_regs
[regno
])
1760 && ! (regno
< FIRST_PSEUDO_REGISTER
&& global_regs
[regno
]))
1761 /* && regno != STACK_POINTER_REGNUM) -- let's try without this. */
1763 register int offset
= regno
/ REGSET_ELT_BITS
;
1764 register REGSET_ELT_TYPE bit
1765 = (REGSET_ELT_TYPE
) 1 << (regno
% REGSET_ELT_BITS
);
1766 REGSET_ELT_TYPE all_needed
= (needed
[offset
] & bit
);
1767 REGSET_ELT_TYPE some_needed
= (needed
[offset
] & bit
);
1769 /* Mark it as a significant register for this basic block. */
1771 significant
[offset
] |= bit
;
1773 /* Mark it as as dead before this insn. */
1774 dead
[offset
] |= bit
;
1776 /* A hard reg in a wide mode may really be multiple registers.
1777 If so, mark all of them just like the first. */
1778 if (regno
< FIRST_PSEUDO_REGISTER
)
1782 /* Nothing below is needed for the stack pointer; get out asap.
1783 Eg, log links aren't needed, since combine won't use them. */
1784 if (regno
== STACK_POINTER_REGNUM
)
1787 n
= HARD_REGNO_NREGS (regno
, GET_MODE (reg
));
1791 significant
[(regno
+ n
) / REGSET_ELT_BITS
]
1792 |= (REGSET_ELT_TYPE
) 1 << ((regno
+ n
) % REGSET_ELT_BITS
);
1793 dead
[(regno
+ n
) / REGSET_ELT_BITS
]
1794 |= (REGSET_ELT_TYPE
) 1 << ((regno
+ n
) % REGSET_ELT_BITS
);
1796 |= (needed
[(regno
+ n
) / REGSET_ELT_BITS
]
1797 & (REGSET_ELT_TYPE
) 1 << ((regno
+ n
) % REGSET_ELT_BITS
));
1799 &= (needed
[(regno
+ n
) / REGSET_ELT_BITS
]
1800 & (REGSET_ELT_TYPE
) 1 << ((regno
+ n
) % REGSET_ELT_BITS
));
1803 /* Additional data to record if this is the final pass. */
1806 register rtx y
= reg_next_use
[regno
];
1807 register int blocknum
= BLOCK_NUM (insn
);
1809 /* If this is a hard reg, record this function uses the reg. */
1811 if (regno
< FIRST_PSEUDO_REGISTER
)
1814 int endregno
= regno
+ HARD_REGNO_NREGS (regno
, GET_MODE (reg
));
1816 for (i
= regno
; i
< endregno
; i
++)
1818 regs_ever_live
[i
] = 1;
1824 /* Keep track of which basic blocks each reg appears in. */
1826 if (reg_basic_block
[regno
] == REG_BLOCK_UNKNOWN
)
1827 reg_basic_block
[regno
] = blocknum
;
1828 else if (reg_basic_block
[regno
] != blocknum
)
1829 reg_basic_block
[regno
] = REG_BLOCK_GLOBAL
;
1831 /* Count (weighted) references, stores, etc. This counts a
1832 register twice if it is modified, but that is correct. */
1833 reg_n_sets
[regno
]++;
1835 reg_n_refs
[regno
] += loop_depth
;
1837 /* The insns where a reg is live are normally counted
1838 elsewhere, but we want the count to include the insn
1839 where the reg is set, and the normal counting mechanism
1840 would not count it. */
1841 reg_live_length
[regno
]++;
1844 /* The next use is no longer "next", since a store intervenes. */
1845 reg_next_use
[regno
] = 0;
1849 /* Make a logical link from the next following insn
1850 that uses this register, back to this insn.
1851 The following insns have already been processed.
1853 We don't build a LOG_LINK for hard registers containing
1854 in ASM_OPERANDs. If these registers get replaced,
1855 we might wind up changing the semantics of the insn,
1856 even if reload can make what appear to be valid assignments
1858 if (y
&& (BLOCK_NUM (y
) == blocknum
)
1859 && (regno
>= FIRST_PSEUDO_REGISTER
1860 || asm_noperands (PATTERN (y
)) < 0))
1862 = gen_rtx (INSN_LIST
, VOIDmode
, insn
, LOG_LINKS (y
));
1864 else if (! some_needed
)
1866 /* Note that dead stores have already been deleted when possible
1867 If we get here, we have found a dead store that cannot
1868 be eliminated (because the same insn does something useful).
1869 Indicate this by marking the reg being set as dying here. */
1871 = gen_rtx (EXPR_LIST
, REG_UNUSED
, reg
, REG_NOTES (insn
));
1872 reg_n_deaths
[REGNO (reg
)]++;
1876 /* This is a case where we have a multi-word hard register
1877 and some, but not all, of the words of the register are
1878 needed in subsequent insns. Write REG_UNUSED notes
1879 for those parts that were not needed. This case should
1884 for (i
= HARD_REGNO_NREGS (regno
, GET_MODE (reg
)) - 1;
1886 if ((needed
[(regno
+ i
) / REGSET_ELT_BITS
]
1887 & ((REGSET_ELT_TYPE
) 1
1888 << ((regno
+ i
) % REGSET_ELT_BITS
))) == 0)
1890 = gen_rtx (EXPR_LIST
, REG_UNUSED
,
1891 gen_rtx (REG
, word_mode
, regno
+ i
),
1897 /* If this is the last pass and this is a SCRATCH, show it will be dying
1898 here and count it. */
1899 else if (GET_CODE (reg
) == SCRATCH
&& insn
!= 0)
1902 = gen_rtx (EXPR_LIST
, REG_UNUSED
, reg
, REG_NOTES (insn
));
1909 /* X is a MEM found in INSN. See if we can convert it into an auto-increment
1913 find_auto_inc (needed
, x
, insn
)
1918 rtx addr
= XEXP (x
, 0);
1921 /* Here we detect use of an index register which might be good for
1922 postincrement, postdecrement, preincrement, or predecrement. */
1924 if (GET_CODE (addr
) == PLUS
&& GET_CODE (XEXP (addr
, 1)) == CONST_INT
)
1925 offset
= INTVAL (XEXP (addr
, 1)), addr
= XEXP (addr
, 0);
1927 if (GET_CODE (addr
) == REG
)
1930 register int size
= GET_MODE_SIZE (GET_MODE (x
));
1933 int regno
= REGNO (addr
);
1935 /* Is the next use an increment that might make auto-increment? */
1936 incr
= reg_next_use
[regno
];
1937 if (incr
&& GET_CODE (PATTERN (incr
)) == SET
1938 && BLOCK_NUM (incr
) == BLOCK_NUM (insn
)
1939 /* Can't add side effects to jumps; if reg is spilled and
1940 reloaded, there's no way to store back the altered value. */
1941 && GET_CODE (insn
) != JUMP_INSN
1942 && (y
= SET_SRC (PATTERN (incr
)), GET_CODE (y
) == PLUS
)
1943 && XEXP (y
, 0) == addr
1944 && GET_CODE (XEXP (y
, 1)) == CONST_INT
1946 #ifdef HAVE_POST_INCREMENT
1947 || (INTVAL (XEXP (y
, 1)) == size
&& offset
== 0)
1949 #ifdef HAVE_POST_DECREMENT
1950 || (INTVAL (XEXP (y
, 1)) == - size
&& offset
== 0)
1952 #ifdef HAVE_PRE_INCREMENT
1953 || (INTVAL (XEXP (y
, 1)) == size
&& offset
== size
)
1955 #ifdef HAVE_PRE_DECREMENT
1956 || (INTVAL (XEXP (y
, 1)) == - size
&& offset
== - size
)
1959 /* Make sure this reg appears only once in this insn. */
1960 && (use
= find_use_as_address (PATTERN (insn
), addr
, offset
),
1961 use
!= 0 && use
!= (rtx
) 1))
1964 rtx q
= SET_DEST (PATTERN (incr
));
1966 if (dead_or_set_p (incr
, addr
))
1968 else if (GET_CODE (q
) == REG
&& ! reg_used_between_p (q
, insn
, incr
))
1970 /* We have *p followed by q = p+size.
1971 Both p and q must be live afterward,
1972 and q must be dead before.
1973 Change it to q = p, ...*q..., q = q+size.
1974 Then fall into the usual case. */
1978 emit_move_insn (q
, addr
);
1979 insns
= get_insns ();
1982 /* If anything in INSNS have UID's that don't fit within the
1983 extra space we allocate earlier, we can't make this auto-inc.
1984 This should never happen. */
1985 for (temp
= insns
; temp
; temp
= NEXT_INSN (temp
))
1987 if (INSN_UID (temp
) > max_uid_for_flow
)
1989 BLOCK_NUM (temp
) = BLOCK_NUM (insn
);
1992 emit_insns_before (insns
, insn
);
1994 if (basic_block_head
[BLOCK_NUM (insn
)] == insn
)
1995 basic_block_head
[BLOCK_NUM (insn
)] = insns
;
2000 /* INCR will become a NOTE and INSN won't contain a
2001 use of ADDR. If a use of ADDR was just placed in
2002 the insn before INSN, make that the next use.
2003 Otherwise, invalidate it. */
2004 if (GET_CODE (PREV_INSN (insn
)) == INSN
2005 && GET_CODE (PATTERN (PREV_INSN (insn
))) == SET
2006 && SET_SRC (PATTERN (PREV_INSN (insn
))) == addr
)
2007 reg_next_use
[regno
] = PREV_INSN (insn
);
2009 reg_next_use
[regno
] = 0;
2015 /* REGNO is now used in INCR which is below INSN, but
2016 it previously wasn't live here. If we don't mark
2017 it as needed, we'll put a REG_DEAD note for it
2018 on this insn, which is incorrect. */
2019 needed
[regno
/ REGSET_ELT_BITS
]
2020 |= (REGSET_ELT_TYPE
) 1 << (regno
% REGSET_ELT_BITS
);
2022 /* If there are any calls between INSN and INCR, show
2023 that REGNO now crosses them. */
2024 for (temp
= insn
; temp
!= incr
; temp
= NEXT_INSN (temp
))
2025 if (GET_CODE (temp
) == CALL_INSN
)
2026 reg_n_calls_crossed
[regno
]++;
2031 /* We have found a suitable auto-increment: do POST_INC around
2032 the register here, and patch out the increment instruction
2034 XEXP (x
, 0) = gen_rtx ((INTVAL (XEXP (y
, 1)) == size
2035 ? (offset
? PRE_INC
: POST_INC
)
2036 : (offset
? PRE_DEC
: POST_DEC
)),
2039 /* Record that this insn has an implicit side effect. */
2041 = gen_rtx (EXPR_LIST
, REG_INC
, addr
, REG_NOTES (insn
));
2043 /* Modify the old increment-insn to simply copy
2044 the already-incremented value of our register. */
2045 SET_SRC (PATTERN (incr
)) = addr
;
2046 /* Indicate insn must be re-recognized. */
2047 INSN_CODE (incr
) = -1;
2049 /* If that makes it a no-op (copying the register into itself)
2050 then delete it so it won't appear to be a "use" and a "set"
2051 of this register. */
2052 if (SET_DEST (PATTERN (incr
)) == addr
)
2054 PUT_CODE (incr
, NOTE
);
2055 NOTE_LINE_NUMBER (incr
) = NOTE_INSN_DELETED
;
2056 NOTE_SOURCE_FILE (incr
) = 0;
2059 if (regno
>= FIRST_PSEUDO_REGISTER
)
2061 /* Count an extra reference to the reg. When a reg is
2062 incremented, spilling it is worse, so we want to make
2063 that less likely. */
2064 reg_n_refs
[regno
] += loop_depth
;
2065 /* Count the increment as a setting of the register,
2066 even though it isn't a SET in rtl. */
2067 reg_n_sets
[regno
]++;
2073 #endif /* AUTO_INC_DEC */
2075 /* Scan expression X and store a 1-bit in LIVE for each reg it uses.
2076 This is done assuming the registers needed from X
2077 are those that have 1-bits in NEEDED.
2079 On the final pass, FINAL is 1. This means try for autoincrement
2080 and count the uses and deaths of each pseudo-reg.
2082 INSN is the containing instruction. If INSN is dead, this function is not
2086 mark_used_regs (needed
, live
, x
, final
, insn
)
2093 register RTX_CODE code
;
2098 code
= GET_CODE (x
);
2120 /* Invalidate the data for the last MEM stored. We could do this only
2121 if the addresses conflict, but this doesn't seem worthwhile. */
2126 find_auto_inc (needed
, x
, insn
);
2131 /* See a register other than being set
2132 => mark it as needed. */
2136 register int offset
= regno
/ REGSET_ELT_BITS
;
2137 register REGSET_ELT_TYPE bit
2138 = (REGSET_ELT_TYPE
) 1 << (regno
% REGSET_ELT_BITS
);
2139 int all_needed
= (needed
[offset
] & bit
) != 0;
2140 int some_needed
= (needed
[offset
] & bit
) != 0;
2142 live
[offset
] |= bit
;
2143 /* A hard reg in a wide mode may really be multiple registers.
2144 If so, mark all of them just like the first. */
2145 if (regno
< FIRST_PSEUDO_REGISTER
)
2149 /* For stack ptr or fixed arg pointer,
2150 nothing below can be necessary, so waste no more time. */
2151 if (regno
== STACK_POINTER_REGNUM
2152 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
2153 || (regno
== ARG_POINTER_REGNUM
&& fixed_regs
[regno
])
2155 || regno
== FRAME_POINTER_REGNUM
)
2157 /* If this is a register we are going to try to eliminate,
2158 don't mark it live here. If we are successful in
2159 eliminating it, it need not be live unless it is used for
2160 pseudos, in which case it will have been set live when
2161 it was allocated to the pseudos. If the register will not
2162 be eliminated, reload will set it live at that point. */
2164 if (! TEST_HARD_REG_BIT (elim_reg_set
, regno
))
2165 regs_ever_live
[regno
] = 1;
2168 /* No death notes for global register variables;
2169 their values are live after this function exits. */
2170 if (global_regs
[regno
])
2173 reg_next_use
[regno
] = insn
;
2177 n
= HARD_REGNO_NREGS (regno
, GET_MODE (x
));
2180 live
[(regno
+ n
) / REGSET_ELT_BITS
]
2181 |= (REGSET_ELT_TYPE
) 1 << ((regno
+ n
) % REGSET_ELT_BITS
);
2183 |= (needed
[(regno
+ n
) / REGSET_ELT_BITS
]
2184 & (REGSET_ELT_TYPE
) 1 << ((regno
+ n
) % REGSET_ELT_BITS
));
2186 &= (needed
[(regno
+ n
) / REGSET_ELT_BITS
]
2187 & (REGSET_ELT_TYPE
) 1 << ((regno
+ n
) % REGSET_ELT_BITS
));
2192 /* Record where each reg is used, so when the reg
2193 is set we know the next insn that uses it. */
2195 reg_next_use
[regno
] = insn
;
2197 if (regno
< FIRST_PSEUDO_REGISTER
)
2199 /* If a hard reg is being used,
2200 record that this function does use it. */
2202 i
= HARD_REGNO_NREGS (regno
, GET_MODE (x
));
2206 regs_ever_live
[regno
+ --i
] = 1;
2211 /* Keep track of which basic block each reg appears in. */
2213 register int blocknum
= BLOCK_NUM (insn
);
2215 if (reg_basic_block
[regno
] == REG_BLOCK_UNKNOWN
)
2216 reg_basic_block
[regno
] = blocknum
;
2217 else if (reg_basic_block
[regno
] != blocknum
)
2218 reg_basic_block
[regno
] = REG_BLOCK_GLOBAL
;
2220 /* Count (weighted) number of uses of each reg. */
2222 reg_n_refs
[regno
] += loop_depth
;
2225 /* Record and count the insns in which a reg dies.
2226 If it is used in this insn and was dead below the insn
2227 then it dies in this insn. If it was set in this insn,
2228 we do not make a REG_DEAD note; likewise if we already
2229 made such a note. */
2232 && ! dead_or_set_p (insn
, x
)
2234 && (regno
>= FIRST_PSEUDO_REGISTER
|| ! fixed_regs
[regno
])
2238 /* If none of the words in X is needed, make a REG_DEAD
2239 note. Otherwise, we must make partial REG_DEAD notes. */
2243 = gen_rtx (EXPR_LIST
, REG_DEAD
, x
, REG_NOTES (insn
));
2244 reg_n_deaths
[regno
]++;
2250 /* Don't make a REG_DEAD note for a part of a register
2251 that is set in the insn. */
2253 for (i
= HARD_REGNO_NREGS (regno
, GET_MODE (x
)) - 1;
2255 if ((needed
[(regno
+ i
) / REGSET_ELT_BITS
]
2256 & ((REGSET_ELT_TYPE
) 1
2257 << ((regno
+ i
) % REGSET_ELT_BITS
))) == 0
2258 && ! dead_or_set_regno_p (insn
, regno
+ i
))
2260 = gen_rtx (EXPR_LIST
, REG_DEAD
,
2261 gen_rtx (REG
, word_mode
, regno
+ i
),
2271 register rtx testreg
= SET_DEST (x
);
2274 /* If storing into MEM, don't show it as being used. But do
2275 show the address as being used. */
2276 if (GET_CODE (testreg
) == MEM
)
2280 find_auto_inc (needed
, testreg
, insn
);
2282 mark_used_regs (needed
, live
, XEXP (testreg
, 0), final
, insn
);
2283 mark_used_regs (needed
, live
, SET_SRC (x
), final
, insn
);
2287 /* Storing in STRICT_LOW_PART is like storing in a reg
2288 in that this SET might be dead, so ignore it in TESTREG.
2289 but in some other ways it is like using the reg.
2291 Storing in a SUBREG or a bit field is like storing the entire
2292 register in that if the register's value is not used
2293 then this SET is not needed. */
2294 while (GET_CODE (testreg
) == STRICT_LOW_PART
2295 || GET_CODE (testreg
) == ZERO_EXTRACT
2296 || GET_CODE (testreg
) == SIGN_EXTRACT
2297 || GET_CODE (testreg
) == SUBREG
)
2299 /* Modifying a single register in an alternate mode
2300 does not use any of the old value. But these other
2301 ways of storing in a register do use the old value. */
2302 if (GET_CODE (testreg
) == SUBREG
2303 && !(REG_SIZE (SUBREG_REG (testreg
)) > REG_SIZE (testreg
)))
2308 testreg
= XEXP (testreg
, 0);
2311 /* If this is a store into a register,
2312 recursively scan the value being stored. */
2314 if (GET_CODE (testreg
) == REG
2315 && (regno
= REGNO (testreg
), regno
!= FRAME_POINTER_REGNUM
)
2316 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
2317 && ! (regno
== ARG_POINTER_REGNUM
&& fixed_regs
[regno
])
2320 /* We used to exclude global_regs here, but that seems wrong.
2321 Storing in them is like storing in mem. */
2323 mark_used_regs (needed
, live
, SET_SRC (x
), final
, insn
);
2325 mark_used_regs (needed
, live
, SET_DEST (x
), final
, insn
);
2332 /* If exiting needs the right stack value, consider this insn as
2333 using the stack pointer. In any event, consider it as using
2334 all global registers. */
2336 #ifdef EXIT_IGNORE_STACK
2337 if (! EXIT_IGNORE_STACK
2338 || (! FRAME_POINTER_REQUIRED
&& flag_omit_frame_pointer
))
2340 live
[STACK_POINTER_REGNUM
/ REGSET_ELT_BITS
]
2341 |= (REGSET_ELT_TYPE
) 1 << (STACK_POINTER_REGNUM
% REGSET_ELT_BITS
);
2343 for (i
= 0; i
< FIRST_PSEUDO_REGISTER
; i
++)
2345 live
[i
/ REGSET_ELT_BITS
]
2346 |= (REGSET_ELT_TYPE
) 1 << (i
% REGSET_ELT_BITS
);
2350 /* Recursively scan the operands of this expression. */
2353 register char *fmt
= GET_RTX_FORMAT (code
);
2356 for (i
= GET_RTX_LENGTH (code
) - 1; i
>= 0; i
--)
2360 /* Tail recursive case: save a function call level. */
2366 mark_used_regs (needed
, live
, XEXP (x
, i
), final
, insn
);
2368 else if (fmt
[i
] == 'E')
2371 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
2372 mark_used_regs (needed
, live
, XVECEXP (x
, i
, j
), final
, insn
);
2381 try_pre_increment_1 (insn
)
2384 /* Find the next use of this reg. If in same basic block,
2385 make it do pre-increment or pre-decrement if appropriate. */
2386 rtx x
= PATTERN (insn
);
2387 HOST_WIDE_INT amount
= ((GET_CODE (SET_SRC (x
)) == PLUS
? 1 : -1)
2388 * INTVAL (XEXP (SET_SRC (x
), 1)));
2389 int regno
= REGNO (SET_DEST (x
));
2390 rtx y
= reg_next_use
[regno
];
2392 && BLOCK_NUM (y
) == BLOCK_NUM (insn
)
2393 && try_pre_increment (y
, SET_DEST (PATTERN (insn
)),
2396 /* We have found a suitable auto-increment
2397 and already changed insn Y to do it.
2398 So flush this increment-instruction. */
2399 PUT_CODE (insn
, NOTE
);
2400 NOTE_LINE_NUMBER (insn
) = NOTE_INSN_DELETED
;
2401 NOTE_SOURCE_FILE (insn
) = 0;
2402 /* Count a reference to this reg for the increment
2403 insn we are deleting. When a reg is incremented.
2404 spilling it is worse, so we want to make that
2406 if (regno
>= FIRST_PSEUDO_REGISTER
)
2408 reg_n_refs
[regno
] += loop_depth
;
2409 reg_n_sets
[regno
]++;
2416 /* Try to change INSN so that it does pre-increment or pre-decrement
2417 addressing on register REG in order to add AMOUNT to REG.
2418 AMOUNT is negative for pre-decrement.
2419 Returns 1 if the change could be made.
2420 This checks all about the validity of the result of modifying INSN. */
2423 try_pre_increment (insn
, reg
, amount
)
2425 HOST_WIDE_INT amount
;
2429 /* Nonzero if we can try to make a pre-increment or pre-decrement.
2430 For example, addl $4,r1; movl (r1),... can become movl +(r1),... */
2432 /* Nonzero if we can try to make a post-increment or post-decrement.
2433 For example, addl $4,r1; movl -4(r1),... can become movl (r1)+,...
2434 It is possible for both PRE_OK and POST_OK to be nonzero if the machine
2435 supports both pre-inc and post-inc, or both pre-dec and post-dec. */
2438 /* Nonzero if the opportunity actually requires post-inc or post-dec. */
2441 /* From the sign of increment, see which possibilities are conceivable
2442 on this target machine. */
2443 #ifdef HAVE_PRE_INCREMENT
2447 #ifdef HAVE_POST_INCREMENT
2452 #ifdef HAVE_PRE_DECREMENT
2456 #ifdef HAVE_POST_DECREMENT
2461 if (! (pre_ok
|| post_ok
))
2464 /* It is not safe to add a side effect to a jump insn
2465 because if the incremented register is spilled and must be reloaded
2466 there would be no way to store the incremented value back in memory. */
2468 if (GET_CODE (insn
) == JUMP_INSN
)
2473 use
= find_use_as_address (PATTERN (insn
), reg
, 0);
2474 if (post_ok
&& (use
== 0 || use
== (rtx
) 1))
2476 use
= find_use_as_address (PATTERN (insn
), reg
, -amount
);
2480 if (use
== 0 || use
== (rtx
) 1)
2483 if (GET_MODE_SIZE (GET_MODE (use
)) != (amount
> 0 ? amount
: - amount
))
2486 XEXP (use
, 0) = gen_rtx (amount
> 0
2487 ? (do_post
? POST_INC
: PRE_INC
)
2488 : (do_post
? POST_DEC
: PRE_DEC
),
2491 /* Record that this insn now has an implicit side effect on X. */
2492 REG_NOTES (insn
) = gen_rtx (EXPR_LIST
, REG_INC
, reg
, REG_NOTES (insn
));
2496 #endif /* AUTO_INC_DEC */
2498 /* Find the place in the rtx X where REG is used as a memory address.
2499 Return the MEM rtx that so uses it.
2500 If PLUSCONST is nonzero, search instead for a memory address equivalent to
2501 (plus REG (const_int PLUSCONST)).
2503 If such an address does not appear, return 0.
2504 If REG appears more than once, or is used other than in such an address,
2508 find_use_as_address (x
, reg
, plusconst
)
2513 enum rtx_code code
= GET_CODE (x
);
2514 char *fmt
= GET_RTX_FORMAT (code
);
2516 register rtx value
= 0;
2519 if (code
== MEM
&& XEXP (x
, 0) == reg
&& plusconst
== 0)
2522 if (code
== MEM
&& GET_CODE (XEXP (x
, 0)) == PLUS
2523 && XEXP (XEXP (x
, 0), 0) == reg
2524 && GET_CODE (XEXP (XEXP (x
, 0), 1)) == CONST_INT
2525 && INTVAL (XEXP (XEXP (x
, 0), 1)) == plusconst
)
2528 if (code
== SIGN_EXTRACT
|| code
== ZERO_EXTRACT
)
2530 /* If REG occurs inside a MEM used in a bit-field reference,
2531 that is unacceptable. */
2532 if (find_use_as_address (XEXP (x
, 0), reg
, 0) != 0)
2533 return (rtx
) (HOST_WIDE_INT
) 1;
2537 return (rtx
) (HOST_WIDE_INT
) 1;
2539 for (i
= GET_RTX_LENGTH (code
) - 1; i
>= 0; i
--)
2543 tem
= find_use_as_address (XEXP (x
, i
), reg
, plusconst
);
2547 return (rtx
) (HOST_WIDE_INT
) 1;
2552 for (j
= XVECLEN (x
, i
) - 1; j
>= 0; j
--)
2554 tem
= find_use_as_address (XVECEXP (x
, i
, j
), reg
, plusconst
);
2558 return (rtx
) (HOST_WIDE_INT
) 1;
2566 /* Write information about registers and basic blocks into FILE.
2567 This is part of making a debugging dump. */
2570 dump_flow_info (file
)
2574 static char *reg_class_names
[] = REG_CLASS_NAMES
;
2576 fprintf (file
, "%d registers.\n", max_regno
);
2578 for (i
= FIRST_PSEUDO_REGISTER
; i
< max_regno
; i
++)
2581 enum reg_class
class, altclass
;
2582 fprintf (file
, "\nRegister %d used %d times across %d insns",
2583 i
, reg_n_refs
[i
], reg_live_length
[i
]);
2584 if (reg_basic_block
[i
] >= 0)
2585 fprintf (file
, " in block %d", reg_basic_block
[i
]);
2586 if (reg_n_deaths
[i
] != 1)
2587 fprintf (file
, "; dies in %d places", reg_n_deaths
[i
]);
2588 if (reg_n_calls_crossed
[i
] == 1)
2589 fprintf (file
, "; crosses 1 call");
2590 else if (reg_n_calls_crossed
[i
])
2591 fprintf (file
, "; crosses %d calls", reg_n_calls_crossed
[i
]);
2592 if (PSEUDO_REGNO_BYTES (i
) != UNITS_PER_WORD
)
2593 fprintf (file
, "; %d bytes", PSEUDO_REGNO_BYTES (i
));
2594 class = reg_preferred_class (i
);
2595 altclass
= reg_alternate_class (i
);
2596 if (class != GENERAL_REGS
|| altclass
!= ALL_REGS
)
2598 if (altclass
== ALL_REGS
|| class == ALL_REGS
)
2599 fprintf (file
, "; pref %s", reg_class_names
[(int) class]);
2600 else if (altclass
== NO_REGS
)
2601 fprintf (file
, "; %s or none", reg_class_names
[(int) class]);
2603 fprintf (file
, "; pref %s, else %s",
2604 reg_class_names
[(int) class],
2605 reg_class_names
[(int) altclass
]);
2607 if (REGNO_POINTER_FLAG (i
))
2608 fprintf (file
, "; pointer");
2609 fprintf (file
, ".\n");
2611 fprintf (file
, "\n%d basic blocks.\n", n_basic_blocks
);
2612 for (i
= 0; i
< n_basic_blocks
; i
++)
2614 register rtx head
, jump
;
2616 fprintf (file
, "\nBasic block %d: first insn %d, last %d.\n",
2618 INSN_UID (basic_block_head
[i
]),
2619 INSN_UID (basic_block_end
[i
]));
2620 /* The control flow graph's storage is freed
2621 now when flow_analysis returns.
2622 Don't try to print it if it is gone. */
2623 if (basic_block_drops_in
)
2625 fprintf (file
, "Reached from blocks: ");
2626 head
= basic_block_head
[i
];
2627 if (GET_CODE (head
) == CODE_LABEL
)
2628 for (jump
= LABEL_REFS (head
);
2630 jump
= LABEL_NEXTREF (jump
))
2632 register int from_block
= BLOCK_NUM (CONTAINING_INSN (jump
));
2633 fprintf (file
, " %d", from_block
);
2635 if (basic_block_drops_in
[i
])
2636 fprintf (file
, " previous");
2638 fprintf (file
, "\nRegisters live at start:");
2639 for (regno
= 0; regno
< max_regno
; regno
++)
2641 register int offset
= regno
/ REGSET_ELT_BITS
;
2642 register int bit
= 1 << (regno
% REGSET_ELT_BITS
);
2643 if (basic_block_live_at_start
[i
][offset
] & bit
)
2644 fprintf (file
, " %d", regno
);
2646 fprintf (file
, "\n");
2648 fprintf (file
, "\n");