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 int *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 int *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.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 = (int *) alloca ((max_uid_for_flow
+ 1) * sizeof (int));
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 (in this function)
480 that are referenced by non-jump instructions. */
483 for (x
= label_value_list
; x
; x
= XEXP (x
, 1))
484 if (! LABEL_REF_NONLOCAL_P (x
))
485 block_live
[BLOCK_NUM (XEXP (x
, 0))] = 1;
488 /* Record which basic blocks control can drop in to. */
492 for (i
= 0; i
< n_basic_blocks
; i
++)
494 register rtx insn
= PREV_INSN (basic_block_head
[i
]);
495 /* TEMP1 is used to avoid a bug in Sequent's compiler. */
497 while (insn
&& GET_CODE (insn
) == NOTE
)
498 insn
= PREV_INSN (insn
);
499 temp1
= insn
&& GET_CODE (insn
) != BARRIER
;
500 basic_block_drops_in
[i
] = temp1
;
504 /* Now find which basic blocks can actually be reached
505 and put all jump insns' LABEL_REFS onto the ref-chains
506 of their target labels. */
508 if (n_basic_blocks
> 0)
510 int something_marked
= 1;
512 /* Find all indirect jump insns and mark them as possibly jumping
513 to all the labels whose addresses are explicitly used.
514 This is because, when there are computed gotos,
515 we can't tell which labels they jump to, of all the possibilities. */
517 for (insn
= f
; insn
; insn
= NEXT_INSN (insn
))
518 if (GET_CODE (insn
) == JUMP_INSN
519 && GET_CODE (PATTERN (insn
)) == SET
520 && SET_DEST (PATTERN (insn
)) == pc_rtx
521 && (GET_CODE (SET_SRC (PATTERN (insn
))) == REG
522 || GET_CODE (SET_SRC (PATTERN (insn
))) == MEM
))
525 for (x
= label_value_list
; x
; x
= XEXP (x
, 1))
526 mark_label_ref (gen_rtx (LABEL_REF
, VOIDmode
, XEXP (x
, 0)),
528 for (x
= forced_labels
; x
; x
= XEXP (x
, 1))
529 mark_label_ref (gen_rtx (LABEL_REF
, VOIDmode
, XEXP (x
, 0)),
533 /* Find all call insns and mark them as possibly jumping
534 to all the nonlocal goto handler labels. */
536 for (insn
= f
; insn
; insn
= NEXT_INSN (insn
))
537 if (GET_CODE (insn
) == CALL_INSN
)
540 for (x
= nonlocal_label_list
; x
; x
= XEXP (x
, 1))
541 /* Don't try marking labels that
542 were deleted as unreferenced. */
543 if (GET_CODE (XEXP (x
, 0)) == CODE_LABEL
)
544 mark_label_ref (gen_rtx (LABEL_REF
, VOIDmode
, XEXP (x
, 0)),
546 /* ??? This could be made smarter:
547 in some cases it's possible to tell that certain
548 calls will not do a nonlocal goto.
550 For example, if the nested functions that do the
551 nonlocal gotos do not have their addresses taken, then
552 only calls to those functions or to other nested
553 functions that use them could possibly do nonlocal
557 /* Pass over all blocks, marking each block that is reachable
558 and has not yet been marked.
559 Keep doing this until, in one pass, no blocks have been marked.
560 Then blocks_live and blocks_marked are identical and correct.
561 In addition, all jumps actually reachable have been marked. */
563 while (something_marked
)
565 something_marked
= 0;
566 for (i
= 0; i
< n_basic_blocks
; i
++)
567 if (block_live
[i
] && !block_marked
[i
])
570 something_marked
= 1;
571 if (i
+ 1 < n_basic_blocks
&& basic_block_drops_in
[i
+ 1])
572 block_live
[i
+ 1] = 1;
573 insn
= basic_block_end
[i
];
574 if (GET_CODE (insn
) == JUMP_INSN
)
575 mark_label_ref (PATTERN (insn
), insn
, 0);
579 /* Now delete the code for any basic blocks that can't be reached.
580 They can occur because jump_optimize does not recognize
581 unreachable loops as unreachable. */
583 for (i
= 0; i
< n_basic_blocks
; i
++)
586 insn
= basic_block_head
[i
];
589 if (GET_CODE (insn
) == BARRIER
)
591 if (GET_CODE (insn
) != NOTE
)
593 PUT_CODE (insn
, NOTE
);
594 NOTE_LINE_NUMBER (insn
) = NOTE_INSN_DELETED
;
595 NOTE_SOURCE_FILE (insn
) = 0;
597 if (insn
== basic_block_end
[i
])
599 /* BARRIERs are between basic blocks, not part of one.
600 Delete a BARRIER if the preceding jump is deleted.
601 We cannot alter a BARRIER into a NOTE
602 because it is too short; but we can really delete
603 it because it is not part of a basic block. */
604 if (NEXT_INSN (insn
) != 0
605 && GET_CODE (NEXT_INSN (insn
)) == BARRIER
)
606 delete_insn (NEXT_INSN (insn
));
609 insn
= NEXT_INSN (insn
);
611 /* Each time we delete some basic blocks,
612 see if there is a jump around them that is
613 being turned into a no-op. If so, delete it. */
615 if (block_live
[i
- 1])
618 for (j
= i
; j
< n_basic_blocks
; j
++)
622 insn
= basic_block_end
[i
- 1];
623 if (GET_CODE (insn
) == JUMP_INSN
624 /* An unconditional jump is the only possibility
625 we must check for, since a conditional one
626 would make these blocks live. */
627 && simplejump_p (insn
)
628 && (label
= XEXP (SET_SRC (PATTERN (insn
)), 0), 1)
629 && INSN_UID (label
) != 0
630 && BLOCK_NUM (label
) == j
)
632 PUT_CODE (insn
, NOTE
);
633 NOTE_LINE_NUMBER (insn
) = NOTE_INSN_DELETED
;
634 NOTE_SOURCE_FILE (insn
) = 0;
635 if (GET_CODE (NEXT_INSN (insn
)) != BARRIER
)
637 delete_insn (NEXT_INSN (insn
));
646 /* Check expression X for label references;
647 if one is found, add INSN to the label's chain of references.
649 CHECKDUP means check for and avoid creating duplicate references
650 from the same insn. Such duplicates do no serious harm but
651 can slow life analysis. CHECKDUP is set only when duplicates
655 mark_label_ref (x
, insn
, checkdup
)
659 register RTX_CODE code
;
663 /* We can be called with NULL when scanning label_value_list. */
668 if (code
== LABEL_REF
)
670 register rtx label
= XEXP (x
, 0);
672 if (GET_CODE (label
) != CODE_LABEL
)
674 /* If the label was never emitted, this insn is junk,
675 but avoid a crash trying to refer to BLOCK_NUM (label).
676 This can happen as a result of a syntax error
677 and a diagnostic has already been printed. */
678 if (INSN_UID (label
) == 0)
680 CONTAINING_INSN (x
) = insn
;
681 /* if CHECKDUP is set, check for duplicate ref from same insn
684 for (y
= LABEL_REFS (label
); y
!= label
; y
= LABEL_NEXTREF (y
))
685 if (CONTAINING_INSN (y
) == insn
)
687 LABEL_NEXTREF (x
) = LABEL_REFS (label
);
688 LABEL_REFS (label
) = x
;
689 block_live_static
[BLOCK_NUM (label
)] = 1;
693 fmt
= GET_RTX_FORMAT (code
);
694 for (i
= GET_RTX_LENGTH (code
) - 1; i
>= 0; i
--)
697 mark_label_ref (XEXP (x
, i
), insn
, 0);
701 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
702 mark_label_ref (XVECEXP (x
, i
, j
), insn
, 1);
707 /* Determine which registers are live at the start of each
708 basic block of the function whose first insn is F.
709 NREGS is the number of registers used in F.
710 We allocate the vector basic_block_live_at_start
711 and the regsets that it points to, and fill them with the data.
712 regset_size and regset_bytes are also set here. */
715 life_analysis (f
, nregs
)
722 /* For each basic block, a bitmask of regs
723 live on exit from the block. */
724 regset
*basic_block_live_at_end
;
725 /* For each basic block, a bitmask of regs
726 live on entry to a successor-block of this block.
727 If this does not match basic_block_live_at_end,
728 that must be updated, and the block must be rescanned. */
729 regset
*basic_block_new_live_at_end
;
730 /* For each basic block, a bitmask of regs
731 whose liveness at the end of the basic block
732 can make a difference in which regs are live on entry to the block.
733 These are the regs that are set within the basic block,
734 possibly excluding those that are used after they are set. */
735 regset
*basic_block_significant
;
739 struct obstack flow_obstack
;
741 gcc_obstack_init (&flow_obstack
);
745 bzero (regs_ever_live
, sizeof regs_ever_live
);
747 /* Allocate and zero out many data structures
748 that will record the data from lifetime analysis. */
750 allocate_for_life_analysis ();
752 reg_next_use
= (rtx
*) alloca (nregs
* sizeof (rtx
));
753 bzero (reg_next_use
, nregs
* sizeof (rtx
));
755 /* Set up several regset-vectors used internally within this function.
756 Their meanings are documented above, with their declarations. */
758 basic_block_live_at_end
= (regset
*) alloca (n_basic_blocks
* sizeof (regset
));
759 /* Don't use alloca since that leads to a crash rather than an error message
760 if there isn't enough space.
761 Don't use oballoc since we may need to allocate other things during
762 this function on the temporary obstack. */
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_live_at_end
, tem
, n_basic_blocks
, regset_bytes
);
767 basic_block_new_live_at_end
= (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_new_live_at_end
, tem
, n_basic_blocks
, regset_bytes
);
772 basic_block_significant
= (regset
*) alloca (n_basic_blocks
* sizeof (regset
));
773 tem
= (regset
) obstack_alloc (&flow_obstack
, n_basic_blocks
* regset_bytes
);
774 bzero (tem
, n_basic_blocks
* regset_bytes
);
775 init_regset_vector (basic_block_significant
, tem
, n_basic_blocks
, regset_bytes
);
777 /* Record which insns refer to any volatile memory
778 or for any reason can't be deleted just because they are dead stores.
779 Also, delete any insns that copy a register to itself. */
781 for (insn
= f
; insn
; insn
= NEXT_INSN (insn
))
783 enum rtx_code code1
= GET_CODE (insn
);
784 if (code1
== CALL_INSN
)
785 INSN_VOLATILE (insn
) = 1;
786 else if (code1
== INSN
|| code1
== JUMP_INSN
)
788 /* Delete (in effect) any obvious no-op moves. */
789 if (GET_CODE (PATTERN (insn
)) == SET
790 && GET_CODE (SET_DEST (PATTERN (insn
))) == REG
791 && GET_CODE (SET_SRC (PATTERN (insn
))) == REG
792 && REGNO (SET_DEST (PATTERN (insn
))) ==
793 REGNO (SET_SRC (PATTERN (insn
)))
794 /* Insns carrying these notes are useful later on. */
795 && ! find_reg_note (insn
, REG_EQUAL
, NULL_RTX
))
797 PUT_CODE (insn
, NOTE
);
798 NOTE_LINE_NUMBER (insn
) = NOTE_INSN_DELETED
;
799 NOTE_SOURCE_FILE (insn
) = 0;
801 else if (GET_CODE (PATTERN (insn
)) == PARALLEL
)
803 /* If nothing but SETs of registers to themselves,
804 this insn can also be deleted. */
805 for (i
= 0; i
< XVECLEN (PATTERN (insn
), 0); i
++)
807 rtx tem
= XVECEXP (PATTERN (insn
), 0, i
);
809 if (GET_CODE (tem
) == USE
810 || GET_CODE (tem
) == CLOBBER
)
813 if (GET_CODE (tem
) != SET
814 || GET_CODE (SET_DEST (tem
)) != REG
815 || GET_CODE (SET_SRC (tem
)) != REG
816 || REGNO (SET_DEST (tem
)) != REGNO (SET_SRC (tem
)))
820 if (i
== XVECLEN (PATTERN (insn
), 0)
821 /* Insns carrying these notes are useful later on. */
822 && ! find_reg_note (insn
, REG_EQUAL
, NULL_RTX
))
824 PUT_CODE (insn
, NOTE
);
825 NOTE_LINE_NUMBER (insn
) = NOTE_INSN_DELETED
;
826 NOTE_SOURCE_FILE (insn
) = 0;
829 INSN_VOLATILE (insn
) = volatile_refs_p (PATTERN (insn
));
831 else if (GET_CODE (PATTERN (insn
)) != USE
)
832 INSN_VOLATILE (insn
) = volatile_refs_p (PATTERN (insn
));
833 /* A SET that makes space on the stack cannot be dead.
834 (Such SETs occur only for allocating variable-size data,
835 so they will always have a PLUS or MINUS according to the
836 direction of stack growth.)
837 Even if this function never uses this stack pointer value,
838 signal handlers do! */
839 else if (code1
== INSN
&& GET_CODE (PATTERN (insn
)) == SET
840 && SET_DEST (PATTERN (insn
)) == stack_pointer_rtx
841 #ifdef STACK_GROWS_DOWNWARD
842 && GET_CODE (SET_SRC (PATTERN (insn
))) == MINUS
844 && GET_CODE (SET_SRC (PATTERN (insn
))) == PLUS
846 && XEXP (SET_SRC (PATTERN (insn
)), 0) == stack_pointer_rtx
)
847 INSN_VOLATILE (insn
) = 1;
851 if (n_basic_blocks
> 0)
852 #ifdef EXIT_IGNORE_STACK
853 if (! EXIT_IGNORE_STACK
854 || (! FRAME_POINTER_REQUIRED
&& flag_omit_frame_pointer
))
857 /* If exiting needs the right stack value,
858 consider the stack pointer live at the end of the function. */
859 basic_block_live_at_end
[n_basic_blocks
- 1]
860 [STACK_POINTER_REGNUM
/ REGSET_ELT_BITS
]
861 |= (REGSET_ELT_TYPE
) 1 << (STACK_POINTER_REGNUM
% REGSET_ELT_BITS
);
862 basic_block_new_live_at_end
[n_basic_blocks
- 1]
863 [STACK_POINTER_REGNUM
/ REGSET_ELT_BITS
]
864 |= (REGSET_ELT_TYPE
) 1 << (STACK_POINTER_REGNUM
% REGSET_ELT_BITS
);
867 /* Mark the frame pointer is needed at the end of the function. If
868 we end up eliminating it, it will be removed from the live list
869 of each basic block by reload. */
871 if (n_basic_blocks
> 0)
873 basic_block_live_at_end
[n_basic_blocks
- 1]
874 [FRAME_POINTER_REGNUM
/ REGSET_ELT_BITS
]
875 |= (REGSET_ELT_TYPE
) 1 << (FRAME_POINTER_REGNUM
% REGSET_ELT_BITS
);
876 basic_block_new_live_at_end
[n_basic_blocks
- 1]
877 [FRAME_POINTER_REGNUM
/ REGSET_ELT_BITS
]
878 |= (REGSET_ELT_TYPE
) 1 << (FRAME_POINTER_REGNUM
% REGSET_ELT_BITS
);
881 /* Mark all global registers as being live at the end of the function
882 since they may be referenced by our caller. */
884 if (n_basic_blocks
> 0)
885 for (i
= 0; i
< FIRST_PSEUDO_REGISTER
; i
++)
888 basic_block_live_at_end
[n_basic_blocks
- 1]
889 [i
/ REGSET_ELT_BITS
]
890 |= (REGSET_ELT_TYPE
) 1 << (i
% REGSET_ELT_BITS
);
891 basic_block_new_live_at_end
[n_basic_blocks
- 1]
892 [i
/ REGSET_ELT_BITS
]
893 |= (REGSET_ELT_TYPE
) 1 << (i
% REGSET_ELT_BITS
);
896 /* Propagate life info through the basic blocks
897 around the graph of basic blocks.
899 This is a relaxation process: each time a new register
900 is live at the end of the basic block, we must scan the block
901 to determine which registers are, as a consequence, live at the beginning
902 of that block. These registers must then be marked live at the ends
903 of all the blocks that can transfer control to that block.
904 The process continues until it reaches a fixed point. */
911 for (i
= n_basic_blocks
- 1; i
>= 0; i
--)
913 int consider
= first_pass
;
914 int must_rescan
= first_pass
;
919 /* Set CONSIDER if this block needs thinking about at all
920 (that is, if the regs live now at the end of it
921 are not the same as were live at the end of it when
922 we last thought about it).
923 Set must_rescan if it needs to be thought about
924 instruction by instruction (that is, if any additional
925 reg that is live at the end now but was not live there before
926 is one of the significant regs of this basic block). */
928 for (j
= 0; j
< regset_size
; j
++)
930 register REGSET_ELT_TYPE x
931 = (basic_block_new_live_at_end
[i
][j
]
932 & ~basic_block_live_at_end
[i
][j
]);
935 if (x
& basic_block_significant
[i
][j
])
947 /* The live_at_start of this block may be changing,
948 so another pass will be required after this one. */
953 /* No complete rescan needed;
954 just record those variables newly known live at end
955 as live at start as well. */
956 for (j
= 0; j
< regset_size
; j
++)
958 register REGSET_ELT_TYPE x
959 = (basic_block_new_live_at_end
[i
][j
]
960 & ~basic_block_live_at_end
[i
][j
]);
961 basic_block_live_at_start
[i
][j
] |= x
;
962 basic_block_live_at_end
[i
][j
] |= x
;
967 /* Update the basic_block_live_at_start
968 by propagation backwards through the block. */
969 bcopy (basic_block_new_live_at_end
[i
],
970 basic_block_live_at_end
[i
], regset_bytes
);
971 bcopy (basic_block_live_at_end
[i
],
972 basic_block_live_at_start
[i
], regset_bytes
);
973 propagate_block (basic_block_live_at_start
[i
],
974 basic_block_head
[i
], basic_block_end
[i
], 0,
975 first_pass
? basic_block_significant
[i
]
981 register rtx jump
, head
;
982 /* Update the basic_block_new_live_at_end's of the block
983 that falls through into this one (if any). */
984 head
= basic_block_head
[i
];
985 jump
= PREV_INSN (head
);
986 if (basic_block_drops_in
[i
])
988 register int from_block
= BLOCK_NUM (jump
);
990 for (j
= 0; j
< regset_size
; j
++)
991 basic_block_new_live_at_end
[from_block
][j
]
992 |= basic_block_live_at_start
[i
][j
];
994 /* Update the basic_block_new_live_at_end's of
995 all the blocks that jump to this one. */
996 if (GET_CODE (head
) == CODE_LABEL
)
997 for (jump
= LABEL_REFS (head
);
999 jump
= LABEL_NEXTREF (jump
))
1001 register int from_block
= BLOCK_NUM (CONTAINING_INSN (jump
));
1003 for (j
= 0; j
< regset_size
; j
++)
1004 basic_block_new_live_at_end
[from_block
][j
]
1005 |= basic_block_live_at_start
[i
][j
];
1015 /* The only pseudos that are live at the beginning of the function are
1016 those that were not set anywhere in the function. local-alloc doesn't
1017 know how to handle these correctly, so mark them as not local to any
1020 if (n_basic_blocks
> 0)
1021 for (i
= FIRST_PSEUDO_REGISTER
; i
< max_regno
; i
++)
1022 if (basic_block_live_at_start
[0][i
/ REGSET_ELT_BITS
]
1023 & ((REGSET_ELT_TYPE
) 1 << (i
% REGSET_ELT_BITS
)))
1024 reg_basic_block
[i
] = REG_BLOCK_GLOBAL
;
1026 /* Now the life information is accurate.
1027 Make one more pass over each basic block
1028 to delete dead stores, create autoincrement addressing
1029 and record how many times each register is used, is set, or dies.
1031 To save time, we operate directly in basic_block_live_at_end[i],
1032 thus destroying it (in fact, converting it into a copy of
1033 basic_block_live_at_start[i]). This is ok now because
1034 basic_block_live_at_end[i] is no longer used past this point. */
1038 for (i
= 0; i
< n_basic_blocks
; i
++)
1040 propagate_block (basic_block_live_at_end
[i
],
1041 basic_block_head
[i
], basic_block_end
[i
], 1,
1049 /* Something live during a setjmp should not be put in a register
1050 on certain machines which restore regs from stack frames
1051 rather than from the jmpbuf.
1052 But we don't need to do this for the user's variables, since
1053 ANSI says only volatile variables need this. */
1054 #ifdef LONGJMP_RESTORE_FROM_STACK
1055 for (i
= FIRST_PSEUDO_REGISTER
; i
< nregs
; i
++)
1056 if (regs_live_at_setjmp
[i
/ REGSET_ELT_BITS
]
1057 & ((REGSET_ELT_TYPE
) 1 << (i
% REGSET_ELT_BITS
))
1058 && regno_reg_rtx
[i
] != 0 && ! REG_USERVAR_P (regno_reg_rtx
[i
]))
1060 reg_live_length
[i
] = -1;
1061 reg_basic_block
[i
] = -1;
1066 /* We have a problem with any pseudoreg that
1067 lives across the setjmp. ANSI says that if a
1068 user variable does not change in value
1069 between the setjmp and the longjmp, then the longjmp preserves it.
1070 This includes longjmp from a place where the pseudo appears dead.
1071 (In principle, the value still exists if it is in scope.)
1072 If the pseudo goes in a hard reg, some other value may occupy
1073 that hard reg where this pseudo is dead, thus clobbering the pseudo.
1074 Conclusion: such a pseudo must not go in a hard reg. */
1075 for (i
= FIRST_PSEUDO_REGISTER
; i
< nregs
; i
++)
1076 if ((regs_live_at_setjmp
[i
/ REGSET_ELT_BITS
]
1077 & ((REGSET_ELT_TYPE
) 1 << (i
% REGSET_ELT_BITS
)))
1078 && regno_reg_rtx
[i
] != 0)
1080 reg_live_length
[i
] = -1;
1081 reg_basic_block
[i
] = -1;
1084 obstack_free (&flow_obstack
, NULL_PTR
);
1087 /* Subroutines of life analysis. */
1089 /* Allocate the permanent data structures that represent the results
1090 of life analysis. Not static since used also for stupid life analysis. */
1093 allocate_for_life_analysis ()
1096 register regset tem
;
1098 regset_size
= ((max_regno
+ REGSET_ELT_BITS
- 1) / REGSET_ELT_BITS
);
1099 regset_bytes
= regset_size
* sizeof (*(regset
)0);
1101 reg_n_refs
= (int *) oballoc (max_regno
* sizeof (int));
1102 bzero (reg_n_refs
, max_regno
* sizeof (int));
1104 reg_n_sets
= (short *) oballoc (max_regno
* sizeof (short));
1105 bzero (reg_n_sets
, max_regno
* sizeof (short));
1107 reg_n_deaths
= (short *) oballoc (max_regno
* sizeof (short));
1108 bzero (reg_n_deaths
, max_regno
* sizeof (short));
1110 reg_live_length
= (int *) oballoc (max_regno
* sizeof (int));
1111 bzero (reg_live_length
, max_regno
* sizeof (int));
1113 reg_n_calls_crossed
= (int *) oballoc (max_regno
* sizeof (int));
1114 bzero (reg_n_calls_crossed
, max_regno
* sizeof (int));
1116 reg_basic_block
= (int *) oballoc (max_regno
* sizeof (int));
1117 for (i
= 0; i
< max_regno
; i
++)
1118 reg_basic_block
[i
] = REG_BLOCK_UNKNOWN
;
1120 basic_block_live_at_start
= (regset
*) oballoc (n_basic_blocks
* sizeof (regset
));
1121 tem
= (regset
) oballoc (n_basic_blocks
* regset_bytes
);
1122 bzero (tem
, n_basic_blocks
* regset_bytes
);
1123 init_regset_vector (basic_block_live_at_start
, tem
, n_basic_blocks
, regset_bytes
);
1125 regs_live_at_setjmp
= (regset
) oballoc (regset_bytes
);
1126 bzero (regs_live_at_setjmp
, regset_bytes
);
1129 /* Make each element of VECTOR point at a regset,
1130 taking the space for all those regsets from SPACE.
1131 SPACE is of type regset, but it is really as long as NELTS regsets.
1132 BYTES_PER_ELT is the number of bytes in one regset. */
1135 init_regset_vector (vector
, space
, nelts
, bytes_per_elt
)
1142 register regset p
= space
;
1144 for (i
= 0; i
< nelts
; i
++)
1147 p
+= bytes_per_elt
/ sizeof (*p
);
1151 /* Compute the registers live at the beginning of a basic block
1152 from those live at the end.
1154 When called, OLD contains those live at the end.
1155 On return, it contains those live at the beginning.
1156 FIRST and LAST are the first and last insns of the basic block.
1158 FINAL is nonzero if we are doing the final pass which is not
1159 for computing the life info (since that has already been done)
1160 but for acting on it. On this pass, we delete dead stores,
1161 set up the logical links and dead-variables lists of instructions,
1162 and merge instructions for autoincrement and autodecrement addresses.
1164 SIGNIFICANT is nonzero only the first time for each basic block.
1165 If it is nonzero, it points to a regset in which we store
1166 a 1 for each register that is set within the block.
1168 BNUM is the number of the basic block. */
1171 propagate_block (old
, first
, last
, final
, significant
, bnum
)
1172 register regset old
;
1184 /* The following variables are used only if FINAL is nonzero. */
1185 /* This vector gets one element for each reg that has been live
1186 at any point in the basic block that has been scanned so far.
1187 SOMETIMES_MAX says how many elements are in use so far.
1188 In each element, OFFSET is the byte-number within a regset
1189 for the register described by the element, and BIT is a mask
1190 for that register's bit within the byte. */
1191 register struct sometimes
{ short offset
; short bit
; } *regs_sometimes_live
;
1192 int sometimes_max
= 0;
1193 /* This regset has 1 for each reg that we have seen live so far.
1194 It and REGS_SOMETIMES_LIVE are updated together. */
1197 /* The loop depth may change in the middle of a basic block. Since we
1198 scan from end to beginning, we start with the depth at the end of the
1199 current basic block, and adjust as we pass ends and starts of loops. */
1200 loop_depth
= basic_block_loop_depth
[bnum
];
1202 dead
= (regset
) alloca (regset_bytes
);
1203 live
= (regset
) alloca (regset_bytes
);
1208 /* Include any notes at the end of the block in the scan.
1209 This is in case the block ends with a call to setjmp. */
1211 while (NEXT_INSN (last
) != 0 && GET_CODE (NEXT_INSN (last
)) == NOTE
)
1213 /* Look for loop boundaries, we are going forward here. */
1214 last
= NEXT_INSN (last
);
1215 if (NOTE_LINE_NUMBER (last
) == NOTE_INSN_LOOP_BEG
)
1217 else if (NOTE_LINE_NUMBER (last
) == NOTE_INSN_LOOP_END
)
1223 register int i
, offset
;
1224 REGSET_ELT_TYPE bit
;
1227 maxlive
= (regset
) alloca (regset_bytes
);
1228 bcopy (old
, maxlive
, regset_bytes
);
1230 = (struct sometimes
*) alloca (max_regno
* sizeof (struct sometimes
));
1232 /* Process the regs live at the end of the block.
1233 Enter them in MAXLIVE and REGS_SOMETIMES_LIVE.
1234 Also mark them as not local to any one basic block. */
1236 for (offset
= 0, i
= 0; offset
< regset_size
; offset
++)
1237 for (bit
= 1; bit
; bit
<<= 1, i
++)
1241 if (old
[offset
] & bit
)
1243 reg_basic_block
[i
] = REG_BLOCK_GLOBAL
;
1244 regs_sometimes_live
[sometimes_max
].offset
= offset
;
1245 regs_sometimes_live
[sometimes_max
].bit
= i
% REGSET_ELT_BITS
;
1251 /* Scan the block an insn at a time from end to beginning. */
1253 for (insn
= last
; ; insn
= prev
)
1255 prev
= PREV_INSN (insn
);
1257 /* Look for loop boundaries, remembering that we are going backwards. */
1258 if (GET_CODE (insn
) == NOTE
1259 && NOTE_LINE_NUMBER (insn
) == NOTE_INSN_LOOP_END
)
1261 else if (GET_CODE (insn
) == NOTE
1262 && NOTE_LINE_NUMBER (insn
) == NOTE_INSN_LOOP_BEG
)
1265 /* If we have LOOP_DEPTH == 0, there has been a bookkeeping error.
1266 Abort now rather than setting register status incorrectly. */
1267 if (loop_depth
== 0)
1270 /* If this is a call to `setjmp' et al,
1271 warn if any non-volatile datum is live. */
1273 if (final
&& GET_CODE (insn
) == NOTE
1274 && NOTE_LINE_NUMBER (insn
) == NOTE_INSN_SETJMP
)
1277 for (i
= 0; i
< regset_size
; i
++)
1278 regs_live_at_setjmp
[i
] |= old
[i
];
1281 /* Update the life-status of regs for this insn.
1282 First DEAD gets which regs are set in this insn
1283 then LIVE gets which regs are used in this insn.
1284 Then the regs live before the insn
1285 are those live after, with DEAD regs turned off,
1286 and then LIVE regs turned on. */
1288 if (GET_RTX_CLASS (GET_CODE (insn
)) == 'i')
1291 rtx note
= find_reg_note (insn
, REG_RETVAL
, NULL_RTX
);
1293 = (insn_dead_p (PATTERN (insn
), old
, 0)
1294 /* Don't delete something that refers to volatile storage! */
1295 && ! INSN_VOLATILE (insn
));
1297 = (insn_is_dead
&& note
!= 0
1298 && libcall_dead_p (PATTERN (insn
), old
, note
, insn
));
1300 /* If an instruction consists of just dead store(s) on final pass,
1301 "delete" it by turning it into a NOTE of type NOTE_INSN_DELETED.
1302 We could really delete it with delete_insn, but that
1303 can cause trouble for first or last insn in a basic block. */
1304 if (final
&& insn_is_dead
)
1306 PUT_CODE (insn
, NOTE
);
1307 NOTE_LINE_NUMBER (insn
) = NOTE_INSN_DELETED
;
1308 NOTE_SOURCE_FILE (insn
) = 0;
1310 /* CC0 is now known to be dead. Either this insn used it,
1311 in which case it doesn't anymore, or clobbered it,
1312 so the next insn can't use it. */
1315 /* If this insn is copying the return value from a library call,
1316 delete the entire library call. */
1317 if (libcall_is_dead
)
1319 rtx first
= XEXP (note
, 0);
1321 while (INSN_DELETED_P (first
))
1322 first
= NEXT_INSN (first
);
1327 NOTE_LINE_NUMBER (p
) = NOTE_INSN_DELETED
;
1328 NOTE_SOURCE_FILE (p
) = 0;
1334 for (i
= 0; i
< regset_size
; i
++)
1336 dead
[i
] = 0; /* Faster than bzero here */
1337 live
[i
] = 0; /* since regset_size is usually small */
1340 /* See if this is an increment or decrement that can be
1341 merged into a following memory address. */
1344 register rtx x
= PATTERN (insn
);
1345 /* Does this instruction increment or decrement a register? */
1346 if (final
&& GET_CODE (x
) == SET
1347 && GET_CODE (SET_DEST (x
)) == REG
1348 && (GET_CODE (SET_SRC (x
)) == PLUS
1349 || GET_CODE (SET_SRC (x
)) == MINUS
)
1350 && XEXP (SET_SRC (x
), 0) == SET_DEST (x
)
1351 && GET_CODE (XEXP (SET_SRC (x
), 1)) == CONST_INT
1352 /* Ok, look for a following memory ref we can combine with.
1353 If one is found, change the memory ref to a PRE_INC
1354 or PRE_DEC, cancel this insn, and return 1.
1355 Return 0 if nothing has been done. */
1356 && try_pre_increment_1 (insn
))
1359 #endif /* AUTO_INC_DEC */
1361 /* If this is not the final pass, and this insn is copying the
1362 value of a library call and it's dead, don't scan the
1363 insns that perform the library call, so that the call's
1364 arguments are not marked live. */
1365 if (libcall_is_dead
)
1367 /* Mark the dest reg as `significant'. */
1368 mark_set_regs (old
, dead
, PATTERN (insn
), NULL_RTX
, significant
);
1370 insn
= XEXP (note
, 0);
1371 prev
= PREV_INSN (insn
);
1373 else if (GET_CODE (PATTERN (insn
)) == SET
1374 && SET_DEST (PATTERN (insn
)) == stack_pointer_rtx
1375 && GET_CODE (SET_SRC (PATTERN (insn
))) == PLUS
1376 && XEXP (SET_SRC (PATTERN (insn
)), 0) == stack_pointer_rtx
1377 && GET_CODE (XEXP (SET_SRC (PATTERN (insn
)), 1)) == CONST_INT
)
1378 /* We have an insn to pop a constant amount off the stack.
1379 (Such insns use PLUS regardless of the direction of the stack,
1380 and any insn to adjust the stack by a constant is always a pop.)
1381 These insns, if not dead stores, have no effect on life. */
1385 /* LIVE gets the regs used in INSN;
1386 DEAD gets those set by it. Dead insns don't make anything
1389 mark_set_regs (old
, dead
, PATTERN (insn
),
1390 final
? insn
: NULL_RTX
, significant
);
1392 /* If an insn doesn't use CC0, it becomes dead since we
1393 assume that every insn clobbers it. So show it dead here;
1394 mark_used_regs will set it live if it is referenced. */
1398 mark_used_regs (old
, live
, PATTERN (insn
), final
, insn
);
1400 /* Sometimes we may have inserted something before INSN (such as
1401 a move) when we make an auto-inc. So ensure we will scan
1404 prev
= PREV_INSN (insn
);
1407 if (! insn_is_dead
&& GET_CODE (insn
) == CALL_INSN
)
1411 /* Each call clobbers all call-clobbered regs that are not
1412 global. Note that the function-value reg is a
1413 call-clobbered reg, and mark_set_regs has already had
1414 a chance to handle it. */
1416 for (i
= 0; i
< FIRST_PSEUDO_REGISTER
; i
++)
1417 if (call_used_regs
[i
] && ! global_regs
[i
])
1418 dead
[i
/ REGSET_ELT_BITS
]
1419 |= ((REGSET_ELT_TYPE
) 1 << (i
% REGSET_ELT_BITS
));
1421 /* The stack ptr is used (honorarily) by a CALL insn. */
1422 live
[STACK_POINTER_REGNUM
/ REGSET_ELT_BITS
]
1423 |= ((REGSET_ELT_TYPE
) 1
1424 << (STACK_POINTER_REGNUM
% REGSET_ELT_BITS
));
1426 /* Calls may also reference any of the global registers,
1427 so they are made live. */
1429 for (i
= 0; i
< FIRST_PSEUDO_REGISTER
; i
++)
1431 live
[i
/ REGSET_ELT_BITS
]
1432 |= ((REGSET_ELT_TYPE
) 1 << (i
% REGSET_ELT_BITS
));
1434 /* Calls also clobber memory. */
1438 /* Update OLD for the registers used or set. */
1439 for (i
= 0; i
< regset_size
; i
++)
1445 if (GET_CODE (insn
) == CALL_INSN
&& final
)
1447 /* Any regs live at the time of a call instruction
1448 must not go in a register clobbered by calls.
1449 Find all regs now live and record this for them. */
1451 register struct sometimes
*p
= regs_sometimes_live
;
1453 for (i
= 0; i
< sometimes_max
; i
++, p
++)
1454 if (old
[p
->offset
] & ((REGSET_ELT_TYPE
) 1 << p
->bit
))
1455 reg_n_calls_crossed
[p
->offset
* REGSET_ELT_BITS
+ p
->bit
]+= 1;
1459 /* On final pass, add any additional sometimes-live regs
1460 into MAXLIVE and REGS_SOMETIMES_LIVE.
1461 Also update counts of how many insns each reg is live at. */
1465 for (i
= 0; i
< regset_size
; i
++)
1467 register REGSET_ELT_TYPE diff
= live
[i
] & ~maxlive
[i
];
1473 for (regno
= 0; diff
&& regno
< REGSET_ELT_BITS
; regno
++)
1474 if (diff
& ((REGSET_ELT_TYPE
) 1 << regno
))
1476 regs_sometimes_live
[sometimes_max
].offset
= i
;
1477 regs_sometimes_live
[sometimes_max
].bit
= regno
;
1478 diff
&= ~ ((REGSET_ELT_TYPE
) 1 << regno
);
1485 register struct sometimes
*p
= regs_sometimes_live
;
1486 for (i
= 0; i
< sometimes_max
; i
++, p
++)
1488 if (old
[p
->offset
] & ((REGSET_ELT_TYPE
) 1 << p
->bit
))
1489 reg_live_length
[p
->offset
* REGSET_ELT_BITS
+ p
->bit
]++;
1499 if (num_scratch
> max_scratch
)
1500 max_scratch
= num_scratch
;
1503 /* Return 1 if X (the body of an insn, or part of it) is just dead stores
1504 (SET expressions whose destinations are registers dead after the insn).
1505 NEEDED is the regset that says which regs are alive after the insn.
1507 Unless CALL_OK is non-zero, an insn is needed if it contains a CALL. */
1510 insn_dead_p (x
, needed
, call_ok
)
1515 register RTX_CODE code
= GET_CODE (x
);
1516 /* If setting something that's a reg or part of one,
1517 see if that register's altered value will be live. */
1521 register rtx r
= SET_DEST (x
);
1522 /* A SET that is a subroutine call cannot be dead. */
1523 if (! call_ok
&& GET_CODE (SET_SRC (x
)) == CALL
)
1527 if (GET_CODE (r
) == CC0
)
1531 if (GET_CODE (r
) == MEM
&& last_mem_set
&& ! MEM_VOLATILE_P (r
)
1532 && rtx_equal_p (r
, last_mem_set
))
1535 while (GET_CODE (r
) == SUBREG
1536 || GET_CODE (r
) == STRICT_LOW_PART
1537 || GET_CODE (r
) == ZERO_EXTRACT
1538 || GET_CODE (r
) == SIGN_EXTRACT
)
1541 if (GET_CODE (r
) == REG
)
1543 register int regno
= REGNO (r
);
1544 register int offset
= regno
/ REGSET_ELT_BITS
;
1545 register REGSET_ELT_TYPE bit
1546 = (REGSET_ELT_TYPE
) 1 << (regno
% REGSET_ELT_BITS
);
1548 /* Don't delete insns to set global regs. */
1549 if ((regno
< FIRST_PSEUDO_REGISTER
&& global_regs
[regno
])
1550 /* Make sure insns to set frame pointer aren't deleted. */
1551 || regno
== FRAME_POINTER_REGNUM
1552 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
1553 /* Make sure insns to set arg pointer are never deleted
1554 (if the arg pointer isn't fixed, there will be a USE for
1555 it, so we can treat it normally). */
1556 || (regno
== ARG_POINTER_REGNUM
&& fixed_regs
[regno
])
1558 || (needed
[offset
] & bit
) != 0)
1561 /* If this is a hard register, verify that subsequent words are
1563 if (regno
< FIRST_PSEUDO_REGISTER
)
1565 int n
= HARD_REGNO_NREGS (regno
, GET_MODE (r
));
1568 if ((needed
[(regno
+ n
) / REGSET_ELT_BITS
]
1569 & ((REGSET_ELT_TYPE
) 1
1570 << ((regno
+ n
) % REGSET_ELT_BITS
))) != 0)
1577 /* If performing several activities,
1578 insn is dead if each activity is individually dead.
1579 Also, CLOBBERs and USEs can be ignored; a CLOBBER or USE
1580 that's inside a PARALLEL doesn't make the insn worth keeping. */
1581 else if (code
== PARALLEL
)
1583 register int i
= XVECLEN (x
, 0);
1584 for (i
--; i
>= 0; i
--)
1586 rtx elt
= XVECEXP (x
, 0, i
);
1587 if (!insn_dead_p (elt
, needed
, call_ok
)
1588 && GET_CODE (elt
) != CLOBBER
1589 && GET_CODE (elt
) != USE
)
1594 /* We do not check CLOBBER or USE here.
1595 An insn consisting of just a CLOBBER or just a USE
1596 should not be deleted. */
1600 /* If X is the pattern of the last insn in a libcall, and assuming X is dead,
1601 return 1 if the entire library call is dead.
1602 This is true if X copies a register (hard or pseudo)
1603 and if the hard return reg of the call insn is dead.
1604 (The caller should have tested the destination of X already for death.)
1606 If this insn doesn't just copy a register, then we don't
1607 have an ordinary libcall. In that case, cse could not have
1608 managed to substitute the source for the dest later on,
1609 so we can assume the libcall is dead.
1611 NEEDED is the bit vector of pseudoregs live before this insn.
1612 NOTE is the REG_RETVAL note of the insn. INSN is the insn itself. */
1615 libcall_dead_p (x
, needed
, note
, insn
)
1621 register RTX_CODE code
= GET_CODE (x
);
1625 register rtx r
= SET_SRC (x
);
1626 if (GET_CODE (r
) == REG
)
1628 rtx call
= XEXP (note
, 0);
1631 /* Find the call insn. */
1632 while (call
!= insn
&& GET_CODE (call
) != CALL_INSN
)
1633 call
= NEXT_INSN (call
);
1635 /* If there is none, do nothing special,
1636 since ordinary death handling can understand these insns. */
1640 /* See if the hard reg holding the value is dead.
1641 If this is a PARALLEL, find the call within it. */
1642 call
= PATTERN (call
);
1643 if (GET_CODE (call
) == PARALLEL
)
1645 for (i
= XVECLEN (call
, 0) - 1; i
>= 0; i
--)
1646 if (GET_CODE (XVECEXP (call
, 0, i
)) == SET
1647 && GET_CODE (SET_SRC (XVECEXP (call
, 0, i
))) == CALL
)
1653 call
= XVECEXP (call
, 0, i
);
1656 return insn_dead_p (call
, needed
, 1);
1662 /* Return 1 if register REGNO was used before it was set.
1663 In other words, if it is live at function entry.
1664 Don't count global regster variables, though. */
1667 regno_uninitialized (regno
)
1670 if (n_basic_blocks
== 0
1671 || (regno
< FIRST_PSEUDO_REGISTER
&& global_regs
[regno
]))
1674 return (basic_block_live_at_start
[0][regno
/ REGSET_ELT_BITS
]
1675 & ((REGSET_ELT_TYPE
) 1 << (regno
% REGSET_ELT_BITS
)));
1678 /* 1 if register REGNO was alive at a place where `setjmp' was called
1679 and was set more than once or is an argument.
1680 Such regs may be clobbered by `longjmp'. */
1683 regno_clobbered_at_setjmp (regno
)
1686 if (n_basic_blocks
== 0)
1689 return ((reg_n_sets
[regno
] > 1
1690 || (basic_block_live_at_start
[0][regno
/ REGSET_ELT_BITS
]
1691 & ((REGSET_ELT_TYPE
) 1 << (regno
% REGSET_ELT_BITS
))))
1692 && (regs_live_at_setjmp
[regno
/ REGSET_ELT_BITS
]
1693 & ((REGSET_ELT_TYPE
) 1 << (regno
% REGSET_ELT_BITS
))));
1696 /* Process the registers that are set within X.
1697 Their bits are set to 1 in the regset DEAD,
1698 because they are dead prior to this insn.
1700 If INSN is nonzero, it is the insn being processed
1701 and the fact that it is nonzero implies this is the FINAL pass
1702 in propagate_block. In this case, various info about register
1703 usage is stored, LOG_LINKS fields of insns are set up. */
1705 static void mark_set_1 ();
1708 mark_set_regs (needed
, dead
, x
, insn
, significant
)
1715 register RTX_CODE code
= GET_CODE (x
);
1717 if (code
== SET
|| code
== CLOBBER
)
1718 mark_set_1 (needed
, dead
, x
, insn
, significant
);
1719 else if (code
== PARALLEL
)
1722 for (i
= XVECLEN (x
, 0) - 1; i
>= 0; i
--)
1724 code
= GET_CODE (XVECEXP (x
, 0, i
));
1725 if (code
== SET
|| code
== CLOBBER
)
1726 mark_set_1 (needed
, dead
, XVECEXP (x
, 0, i
), insn
, significant
);
1731 /* Process a single SET rtx, X. */
1734 mark_set_1 (needed
, dead
, x
, insn
, significant
)
1742 register rtx reg
= SET_DEST (x
);
1744 /* Modifying just one hardware register of a multi-reg value
1745 or just a byte field of a register
1746 does not mean the value from before this insn is now dead.
1747 But it does mean liveness of that register at the end of the block
1750 Within mark_set_1, however, we treat it as if the register is
1751 indeed modified. mark_used_regs will, however, also treat this
1752 register as being used. Thus, we treat these insns as setting a
1753 new value for the register as a function of its old value. This
1754 cases LOG_LINKS to be made appropriately and this will help combine. */
1756 while (GET_CODE (reg
) == SUBREG
|| GET_CODE (reg
) == ZERO_EXTRACT
1757 || GET_CODE (reg
) == SIGN_EXTRACT
1758 || GET_CODE (reg
) == STRICT_LOW_PART
)
1759 reg
= XEXP (reg
, 0);
1761 /* If we are writing into memory or into a register mentioned in the
1762 address of the last thing stored into memory, show we don't know
1763 what the last store was. If we are writing memory, save the address
1764 unless it is volatile. */
1765 if (GET_CODE (reg
) == MEM
1766 || (GET_CODE (reg
) == REG
1767 && last_mem_set
!= 0 && reg_overlap_mentioned_p (reg
, last_mem_set
)))
1770 if (GET_CODE (reg
) == MEM
&& ! side_effects_p (reg
)
1771 /* There are no REG_INC notes for SP, so we can't assume we'll see
1772 everything that invalidates it. To be safe, don't eliminate any
1773 stores though SP; none of them should be redundant anyway. */
1774 && ! reg_mentioned_p (stack_pointer_rtx
, reg
))
1777 if (GET_CODE (reg
) == REG
1778 && (regno
= REGNO (reg
), regno
!= FRAME_POINTER_REGNUM
)
1779 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
1780 && ! (regno
== ARG_POINTER_REGNUM
&& fixed_regs
[regno
])
1782 && ! (regno
< FIRST_PSEUDO_REGISTER
&& global_regs
[regno
]))
1783 /* && regno != STACK_POINTER_REGNUM) -- let's try without this. */
1785 register int offset
= regno
/ REGSET_ELT_BITS
;
1786 register REGSET_ELT_TYPE bit
1787 = (REGSET_ELT_TYPE
) 1 << (regno
% REGSET_ELT_BITS
);
1788 REGSET_ELT_TYPE all_needed
= (needed
[offset
] & bit
);
1789 REGSET_ELT_TYPE some_needed
= (needed
[offset
] & bit
);
1791 /* Mark it as a significant register for this basic block. */
1793 significant
[offset
] |= bit
;
1795 /* Mark it as as dead before this insn. */
1796 dead
[offset
] |= bit
;
1798 /* A hard reg in a wide mode may really be multiple registers.
1799 If so, mark all of them just like the first. */
1800 if (regno
< FIRST_PSEUDO_REGISTER
)
1804 /* Nothing below is needed for the stack pointer; get out asap.
1805 Eg, log links aren't needed, since combine won't use them. */
1806 if (regno
== STACK_POINTER_REGNUM
)
1809 n
= HARD_REGNO_NREGS (regno
, GET_MODE (reg
));
1813 significant
[(regno
+ n
) / REGSET_ELT_BITS
]
1814 |= (REGSET_ELT_TYPE
) 1 << ((regno
+ n
) % REGSET_ELT_BITS
);
1815 dead
[(regno
+ n
) / REGSET_ELT_BITS
]
1816 |= (REGSET_ELT_TYPE
) 1 << ((regno
+ n
) % REGSET_ELT_BITS
);
1818 |= (needed
[(regno
+ n
) / REGSET_ELT_BITS
]
1819 & (REGSET_ELT_TYPE
) 1 << ((regno
+ n
) % REGSET_ELT_BITS
));
1821 &= (needed
[(regno
+ n
) / REGSET_ELT_BITS
]
1822 & (REGSET_ELT_TYPE
) 1 << ((regno
+ n
) % REGSET_ELT_BITS
));
1825 /* Additional data to record if this is the final pass. */
1828 register rtx y
= reg_next_use
[regno
];
1829 register int blocknum
= BLOCK_NUM (insn
);
1831 /* The next use is no longer "next", since a store intervenes. */
1832 reg_next_use
[regno
] = 0;
1834 /* If this is a hard reg, record this function uses the reg. */
1836 if (regno
< FIRST_PSEUDO_REGISTER
)
1839 int endregno
= regno
+ HARD_REGNO_NREGS (regno
, GET_MODE (reg
));
1841 for (i
= regno
; i
< endregno
; i
++)
1843 regs_ever_live
[i
] = 1;
1849 /* Keep track of which basic blocks each reg appears in. */
1851 if (reg_basic_block
[regno
] == REG_BLOCK_UNKNOWN
)
1852 reg_basic_block
[regno
] = blocknum
;
1853 else if (reg_basic_block
[regno
] != blocknum
)
1854 reg_basic_block
[regno
] = REG_BLOCK_GLOBAL
;
1856 /* Count (weighted) references, stores, etc. This counts a
1857 register twice if it is modified, but that is correct. */
1858 reg_n_sets
[regno
]++;
1860 reg_n_refs
[regno
] += loop_depth
;
1862 /* The insns where a reg is live are normally counted
1863 elsewhere, but we want the count to include the insn
1864 where the reg is set, and the normal counting mechanism
1865 would not count it. */
1866 reg_live_length
[regno
]++;
1871 /* Make a logical link from the next following insn
1872 that uses this register, back to this insn.
1873 The following insns have already been processed.
1875 We don't build a LOG_LINK for hard registers containing
1876 in ASM_OPERANDs. If these registers get replaced,
1877 we might wind up changing the semantics of the insn,
1878 even if reload can make what appear to be valid assignments
1880 if (y
&& (BLOCK_NUM (y
) == blocknum
)
1881 && (regno
>= FIRST_PSEUDO_REGISTER
1882 || asm_noperands (PATTERN (y
)) < 0))
1884 = gen_rtx (INSN_LIST
, VOIDmode
, insn
, LOG_LINKS (y
));
1886 else if (! some_needed
)
1888 /* Note that dead stores have already been deleted when possible
1889 If we get here, we have found a dead store that cannot
1890 be eliminated (because the same insn does something useful).
1891 Indicate this by marking the reg being set as dying here. */
1893 = gen_rtx (EXPR_LIST
, REG_UNUSED
, reg
, REG_NOTES (insn
));
1894 reg_n_deaths
[REGNO (reg
)]++;
1898 /* This is a case where we have a multi-word hard register
1899 and some, but not all, of the words of the register are
1900 needed in subsequent insns. Write REG_UNUSED notes
1901 for those parts that were not needed. This case should
1906 for (i
= HARD_REGNO_NREGS (regno
, GET_MODE (reg
)) - 1;
1908 if ((needed
[(regno
+ i
) / REGSET_ELT_BITS
]
1909 & ((REGSET_ELT_TYPE
) 1
1910 << ((regno
+ i
) % REGSET_ELT_BITS
))) == 0)
1912 = gen_rtx (EXPR_LIST
, REG_UNUSED
,
1913 gen_rtx (REG
, word_mode
, regno
+ i
),
1918 else if (GET_CODE (reg
) == REG
)
1919 reg_next_use
[regno
] = 0;
1921 /* If this is the last pass and this is a SCRATCH, show it will be dying
1922 here and count it. */
1923 else if (GET_CODE (reg
) == SCRATCH
&& insn
!= 0)
1926 = gen_rtx (EXPR_LIST
, REG_UNUSED
, reg
, REG_NOTES (insn
));
1933 /* X is a MEM found in INSN. See if we can convert it into an auto-increment
1937 find_auto_inc (needed
, x
, insn
)
1942 rtx addr
= XEXP (x
, 0);
1945 /* Here we detect use of an index register which might be good for
1946 postincrement, postdecrement, preincrement, or predecrement. */
1948 if (GET_CODE (addr
) == PLUS
&& GET_CODE (XEXP (addr
, 1)) == CONST_INT
)
1949 offset
= INTVAL (XEXP (addr
, 1)), addr
= XEXP (addr
, 0);
1951 if (GET_CODE (addr
) == REG
)
1954 register int size
= GET_MODE_SIZE (GET_MODE (x
));
1957 int regno
= REGNO (addr
);
1959 /* Is the next use an increment that might make auto-increment? */
1960 incr
= reg_next_use
[regno
];
1961 if (incr
&& GET_CODE (PATTERN (incr
)) == SET
1962 && BLOCK_NUM (incr
) == BLOCK_NUM (insn
)
1963 /* Can't add side effects to jumps; if reg is spilled and
1964 reloaded, there's no way to store back the altered value. */
1965 && GET_CODE (insn
) != JUMP_INSN
1966 && (y
= SET_SRC (PATTERN (incr
)), GET_CODE (y
) == PLUS
)
1967 && XEXP (y
, 0) == addr
1968 && GET_CODE (XEXP (y
, 1)) == CONST_INT
1970 #ifdef HAVE_POST_INCREMENT
1971 || (INTVAL (XEXP (y
, 1)) == size
&& offset
== 0)
1973 #ifdef HAVE_POST_DECREMENT
1974 || (INTVAL (XEXP (y
, 1)) == - size
&& offset
== 0)
1976 #ifdef HAVE_PRE_INCREMENT
1977 || (INTVAL (XEXP (y
, 1)) == size
&& offset
== size
)
1979 #ifdef HAVE_PRE_DECREMENT
1980 || (INTVAL (XEXP (y
, 1)) == - size
&& offset
== - size
)
1983 /* Make sure this reg appears only once in this insn. */
1984 && (use
= find_use_as_address (PATTERN (insn
), addr
, offset
),
1985 use
!= 0 && use
!= (rtx
) 1))
1988 rtx q
= SET_DEST (PATTERN (incr
));
1990 if (dead_or_set_p (incr
, addr
))
1992 else if (GET_CODE (q
) == REG
&& ! reg_used_between_p (q
, insn
, incr
))
1994 /* We have *p followed by q = p+size.
1995 Both p and q must be live afterward,
1996 and q must be dead before.
1997 Change it to q = p, ...*q..., q = q+size.
1998 Then fall into the usual case. */
2002 emit_move_insn (q
, addr
);
2003 insns
= get_insns ();
2006 /* If anything in INSNS have UID's that don't fit within the
2007 extra space we allocate earlier, we can't make this auto-inc.
2008 This should never happen. */
2009 for (temp
= insns
; temp
; temp
= NEXT_INSN (temp
))
2011 if (INSN_UID (temp
) > max_uid_for_flow
)
2013 BLOCK_NUM (temp
) = BLOCK_NUM (insn
);
2016 emit_insns_before (insns
, insn
);
2018 if (basic_block_head
[BLOCK_NUM (insn
)] == insn
)
2019 basic_block_head
[BLOCK_NUM (insn
)] = insns
;
2024 /* INCR will become a NOTE and INSN won't contain a
2025 use of ADDR. If a use of ADDR was just placed in
2026 the insn before INSN, make that the next use.
2027 Otherwise, invalidate it. */
2028 if (GET_CODE (PREV_INSN (insn
)) == INSN
2029 && GET_CODE (PATTERN (PREV_INSN (insn
))) == SET
2030 && SET_SRC (PATTERN (PREV_INSN (insn
))) == addr
)
2031 reg_next_use
[regno
] = PREV_INSN (insn
);
2033 reg_next_use
[regno
] = 0;
2039 /* REGNO is now used in INCR which is below INSN, but
2040 it previously wasn't live here. If we don't mark
2041 it as needed, we'll put a REG_DEAD note for it
2042 on this insn, which is incorrect. */
2043 needed
[regno
/ REGSET_ELT_BITS
]
2044 |= (REGSET_ELT_TYPE
) 1 << (regno
% REGSET_ELT_BITS
);
2046 /* If there are any calls between INSN and INCR, show
2047 that REGNO now crosses them. */
2048 for (temp
= insn
; temp
!= incr
; temp
= NEXT_INSN (temp
))
2049 if (GET_CODE (temp
) == CALL_INSN
)
2050 reg_n_calls_crossed
[regno
]++;
2055 /* We have found a suitable auto-increment: do POST_INC around
2056 the register here, and patch out the increment instruction
2058 XEXP (x
, 0) = gen_rtx ((INTVAL (XEXP (y
, 1)) == size
2059 ? (offset
? PRE_INC
: POST_INC
)
2060 : (offset
? PRE_DEC
: POST_DEC
)),
2063 /* Record that this insn has an implicit side effect. */
2065 = gen_rtx (EXPR_LIST
, REG_INC
, addr
, REG_NOTES (insn
));
2067 /* Modify the old increment-insn to simply copy
2068 the already-incremented value of our register. */
2069 SET_SRC (PATTERN (incr
)) = addr
;
2070 /* Indicate insn must be re-recognized. */
2071 INSN_CODE (incr
) = -1;
2073 /* If that makes it a no-op (copying the register into itself)
2074 then delete it so it won't appear to be a "use" and a "set"
2075 of this register. */
2076 if (SET_DEST (PATTERN (incr
)) == addr
)
2078 PUT_CODE (incr
, NOTE
);
2079 NOTE_LINE_NUMBER (incr
) = NOTE_INSN_DELETED
;
2080 NOTE_SOURCE_FILE (incr
) = 0;
2083 if (regno
>= FIRST_PSEUDO_REGISTER
)
2085 /* Count an extra reference to the reg. When a reg is
2086 incremented, spilling it is worse, so we want to make
2087 that less likely. */
2088 reg_n_refs
[regno
] += loop_depth
;
2089 /* Count the increment as a setting of the register,
2090 even though it isn't a SET in rtl. */
2091 reg_n_sets
[regno
]++;
2097 #endif /* AUTO_INC_DEC */
2099 /* Scan expression X and store a 1-bit in LIVE for each reg it uses.
2100 This is done assuming the registers needed from X
2101 are those that have 1-bits in NEEDED.
2103 On the final pass, FINAL is 1. This means try for autoincrement
2104 and count the uses and deaths of each pseudo-reg.
2106 INSN is the containing instruction. If INSN is dead, this function is not
2110 mark_used_regs (needed
, live
, x
, final
, insn
)
2117 register RTX_CODE code
;
2122 code
= GET_CODE (x
);
2144 /* Invalidate the data for the last MEM stored. We could do this only
2145 if the addresses conflict, but this doesn't seem worthwhile. */
2150 find_auto_inc (needed
, x
, insn
);
2155 /* See a register other than being set
2156 => mark it as needed. */
2160 register int offset
= regno
/ REGSET_ELT_BITS
;
2161 register REGSET_ELT_TYPE bit
2162 = (REGSET_ELT_TYPE
) 1 << (regno
% REGSET_ELT_BITS
);
2163 REGSET_ELT_TYPE all_needed
= needed
[offset
] & bit
;
2164 REGSET_ELT_TYPE some_needed
= needed
[offset
] & bit
;
2166 live
[offset
] |= bit
;
2167 /* A hard reg in a wide mode may really be multiple registers.
2168 If so, mark all of them just like the first. */
2169 if (regno
< FIRST_PSEUDO_REGISTER
)
2173 /* For stack ptr or fixed arg pointer,
2174 nothing below can be necessary, so waste no more time. */
2175 if (regno
== STACK_POINTER_REGNUM
2176 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
2177 || (regno
== ARG_POINTER_REGNUM
&& fixed_regs
[regno
])
2179 || regno
== FRAME_POINTER_REGNUM
)
2181 /* If this is a register we are going to try to eliminate,
2182 don't mark it live here. If we are successful in
2183 eliminating it, it need not be live unless it is used for
2184 pseudos, in which case it will have been set live when
2185 it was allocated to the pseudos. If the register will not
2186 be eliminated, reload will set it live at that point. */
2188 if (! TEST_HARD_REG_BIT (elim_reg_set
, regno
))
2189 regs_ever_live
[regno
] = 1;
2192 /* No death notes for global register variables;
2193 their values are live after this function exits. */
2194 if (global_regs
[regno
])
2197 reg_next_use
[regno
] = insn
;
2201 n
= HARD_REGNO_NREGS (regno
, GET_MODE (x
));
2204 live
[(regno
+ n
) / REGSET_ELT_BITS
]
2205 |= (REGSET_ELT_TYPE
) 1 << ((regno
+ n
) % REGSET_ELT_BITS
);
2207 |= (needed
[(regno
+ n
) / REGSET_ELT_BITS
]
2208 & (REGSET_ELT_TYPE
) 1 << ((regno
+ n
) % REGSET_ELT_BITS
));
2210 &= (needed
[(regno
+ n
) / REGSET_ELT_BITS
]
2211 & (REGSET_ELT_TYPE
) 1 << ((regno
+ n
) % REGSET_ELT_BITS
));
2216 /* Record where each reg is used, so when the reg
2217 is set we know the next insn that uses it. */
2219 reg_next_use
[regno
] = insn
;
2221 if (regno
< FIRST_PSEUDO_REGISTER
)
2223 /* If a hard reg is being used,
2224 record that this function does use it. */
2226 i
= HARD_REGNO_NREGS (regno
, GET_MODE (x
));
2230 regs_ever_live
[regno
+ --i
] = 1;
2235 /* Keep track of which basic block each reg appears in. */
2237 register int blocknum
= BLOCK_NUM (insn
);
2239 if (reg_basic_block
[regno
] == REG_BLOCK_UNKNOWN
)
2240 reg_basic_block
[regno
] = blocknum
;
2241 else if (reg_basic_block
[regno
] != blocknum
)
2242 reg_basic_block
[regno
] = REG_BLOCK_GLOBAL
;
2244 /* Count (weighted) number of uses of each reg. */
2246 reg_n_refs
[regno
] += loop_depth
;
2249 /* Record and count the insns in which a reg dies.
2250 If it is used in this insn and was dead below the insn
2251 then it dies in this insn. If it was set in this insn,
2252 we do not make a REG_DEAD note; likewise if we already
2253 made such a note. */
2256 && ! dead_or_set_p (insn
, x
)
2258 && (regno
>= FIRST_PSEUDO_REGISTER
|| ! fixed_regs
[regno
])
2262 /* If none of the words in X is needed, make a REG_DEAD
2263 note. Otherwise, we must make partial REG_DEAD notes. */
2267 = gen_rtx (EXPR_LIST
, REG_DEAD
, x
, REG_NOTES (insn
));
2268 reg_n_deaths
[regno
]++;
2274 /* Don't make a REG_DEAD note for a part of a register
2275 that is set in the insn. */
2277 for (i
= HARD_REGNO_NREGS (regno
, GET_MODE (x
)) - 1;
2279 if ((needed
[(regno
+ i
) / REGSET_ELT_BITS
]
2280 & ((REGSET_ELT_TYPE
) 1
2281 << ((regno
+ i
) % REGSET_ELT_BITS
))) == 0
2282 && ! dead_or_set_regno_p (insn
, regno
+ i
))
2284 = gen_rtx (EXPR_LIST
, REG_DEAD
,
2285 gen_rtx (REG
, word_mode
, regno
+ i
),
2295 register rtx testreg
= SET_DEST (x
);
2298 /* If storing into MEM, don't show it as being used. But do
2299 show the address as being used. */
2300 if (GET_CODE (testreg
) == MEM
)
2304 find_auto_inc (needed
, testreg
, insn
);
2306 mark_used_regs (needed
, live
, XEXP (testreg
, 0), final
, insn
);
2307 mark_used_regs (needed
, live
, SET_SRC (x
), final
, insn
);
2311 /* Storing in STRICT_LOW_PART is like storing in a reg
2312 in that this SET might be dead, so ignore it in TESTREG.
2313 but in some other ways it is like using the reg.
2315 Storing in a SUBREG or a bit field is like storing the entire
2316 register in that if the register's value is not used
2317 then this SET is not needed. */
2318 while (GET_CODE (testreg
) == STRICT_LOW_PART
2319 || GET_CODE (testreg
) == ZERO_EXTRACT
2320 || GET_CODE (testreg
) == SIGN_EXTRACT
2321 || GET_CODE (testreg
) == SUBREG
)
2323 /* Modifying a single register in an alternate mode
2324 does not use any of the old value. But these other
2325 ways of storing in a register do use the old value. */
2326 if (GET_CODE (testreg
) == SUBREG
2327 && !(REG_SIZE (SUBREG_REG (testreg
)) > REG_SIZE (testreg
)))
2332 testreg
= XEXP (testreg
, 0);
2335 /* If this is a store into a register,
2336 recursively scan the value being stored. */
2338 if (GET_CODE (testreg
) == REG
2339 && (regno
= REGNO (testreg
), regno
!= FRAME_POINTER_REGNUM
)
2340 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
2341 && ! (regno
== ARG_POINTER_REGNUM
&& fixed_regs
[regno
])
2344 /* We used to exclude global_regs here, but that seems wrong.
2345 Storing in them is like storing in mem. */
2347 mark_used_regs (needed
, live
, SET_SRC (x
), final
, insn
);
2349 mark_used_regs (needed
, live
, SET_DEST (x
), final
, insn
);
2356 /* If exiting needs the right stack value, consider this insn as
2357 using the stack pointer. In any event, consider it as using
2358 all global registers. */
2360 #ifdef EXIT_IGNORE_STACK
2361 if (! EXIT_IGNORE_STACK
2362 || (! FRAME_POINTER_REQUIRED
&& flag_omit_frame_pointer
))
2364 live
[STACK_POINTER_REGNUM
/ REGSET_ELT_BITS
]
2365 |= (REGSET_ELT_TYPE
) 1 << (STACK_POINTER_REGNUM
% REGSET_ELT_BITS
);
2367 for (i
= 0; i
< FIRST_PSEUDO_REGISTER
; i
++)
2369 live
[i
/ REGSET_ELT_BITS
]
2370 |= (REGSET_ELT_TYPE
) 1 << (i
% REGSET_ELT_BITS
);
2374 /* Recursively scan the operands of this expression. */
2377 register char *fmt
= GET_RTX_FORMAT (code
);
2380 for (i
= GET_RTX_LENGTH (code
) - 1; i
>= 0; i
--)
2384 /* Tail recursive case: save a function call level. */
2390 mark_used_regs (needed
, live
, XEXP (x
, i
), final
, insn
);
2392 else if (fmt
[i
] == 'E')
2395 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
2396 mark_used_regs (needed
, live
, XVECEXP (x
, i
, j
), final
, insn
);
2405 try_pre_increment_1 (insn
)
2408 /* Find the next use of this reg. If in same basic block,
2409 make it do pre-increment or pre-decrement if appropriate. */
2410 rtx x
= PATTERN (insn
);
2411 HOST_WIDE_INT amount
= ((GET_CODE (SET_SRC (x
)) == PLUS
? 1 : -1)
2412 * INTVAL (XEXP (SET_SRC (x
), 1)));
2413 int regno
= REGNO (SET_DEST (x
));
2414 rtx y
= reg_next_use
[regno
];
2416 && BLOCK_NUM (y
) == BLOCK_NUM (insn
)
2417 && try_pre_increment (y
, SET_DEST (PATTERN (insn
)),
2420 /* We have found a suitable auto-increment
2421 and already changed insn Y to do it.
2422 So flush this increment-instruction. */
2423 PUT_CODE (insn
, NOTE
);
2424 NOTE_LINE_NUMBER (insn
) = NOTE_INSN_DELETED
;
2425 NOTE_SOURCE_FILE (insn
) = 0;
2426 /* Count a reference to this reg for the increment
2427 insn we are deleting. When a reg is incremented.
2428 spilling it is worse, so we want to make that
2430 if (regno
>= FIRST_PSEUDO_REGISTER
)
2432 reg_n_refs
[regno
] += loop_depth
;
2433 reg_n_sets
[regno
]++;
2440 /* Try to change INSN so that it does pre-increment or pre-decrement
2441 addressing on register REG in order to add AMOUNT to REG.
2442 AMOUNT is negative for pre-decrement.
2443 Returns 1 if the change could be made.
2444 This checks all about the validity of the result of modifying INSN. */
2447 try_pre_increment (insn
, reg
, amount
)
2449 HOST_WIDE_INT amount
;
2453 /* Nonzero if we can try to make a pre-increment or pre-decrement.
2454 For example, addl $4,r1; movl (r1),... can become movl +(r1),... */
2456 /* Nonzero if we can try to make a post-increment or post-decrement.
2457 For example, addl $4,r1; movl -4(r1),... can become movl (r1)+,...
2458 It is possible for both PRE_OK and POST_OK to be nonzero if the machine
2459 supports both pre-inc and post-inc, or both pre-dec and post-dec. */
2462 /* Nonzero if the opportunity actually requires post-inc or post-dec. */
2465 /* From the sign of increment, see which possibilities are conceivable
2466 on this target machine. */
2467 #ifdef HAVE_PRE_INCREMENT
2471 #ifdef HAVE_POST_INCREMENT
2476 #ifdef HAVE_PRE_DECREMENT
2480 #ifdef HAVE_POST_DECREMENT
2485 if (! (pre_ok
|| post_ok
))
2488 /* It is not safe to add a side effect to a jump insn
2489 because if the incremented register is spilled and must be reloaded
2490 there would be no way to store the incremented value back in memory. */
2492 if (GET_CODE (insn
) == JUMP_INSN
)
2497 use
= find_use_as_address (PATTERN (insn
), reg
, 0);
2498 if (post_ok
&& (use
== 0 || use
== (rtx
) 1))
2500 use
= find_use_as_address (PATTERN (insn
), reg
, -amount
);
2504 if (use
== 0 || use
== (rtx
) 1)
2507 if (GET_MODE_SIZE (GET_MODE (use
)) != (amount
> 0 ? amount
: - amount
))
2510 XEXP (use
, 0) = gen_rtx (amount
> 0
2511 ? (do_post
? POST_INC
: PRE_INC
)
2512 : (do_post
? POST_DEC
: PRE_DEC
),
2515 /* Record that this insn now has an implicit side effect on X. */
2516 REG_NOTES (insn
) = gen_rtx (EXPR_LIST
, REG_INC
, reg
, REG_NOTES (insn
));
2520 #endif /* AUTO_INC_DEC */
2522 /* Find the place in the rtx X where REG is used as a memory address.
2523 Return the MEM rtx that so uses it.
2524 If PLUSCONST is nonzero, search instead for a memory address equivalent to
2525 (plus REG (const_int PLUSCONST)).
2527 If such an address does not appear, return 0.
2528 If REG appears more than once, or is used other than in such an address,
2532 find_use_as_address (x
, reg
, plusconst
)
2537 enum rtx_code code
= GET_CODE (x
);
2538 char *fmt
= GET_RTX_FORMAT (code
);
2540 register rtx value
= 0;
2543 if (code
== MEM
&& XEXP (x
, 0) == reg
&& plusconst
== 0)
2546 if (code
== MEM
&& GET_CODE (XEXP (x
, 0)) == PLUS
2547 && XEXP (XEXP (x
, 0), 0) == reg
2548 && GET_CODE (XEXP (XEXP (x
, 0), 1)) == CONST_INT
2549 && INTVAL (XEXP (XEXP (x
, 0), 1)) == plusconst
)
2552 if (code
== SIGN_EXTRACT
|| code
== ZERO_EXTRACT
)
2554 /* If REG occurs inside a MEM used in a bit-field reference,
2555 that is unacceptable. */
2556 if (find_use_as_address (XEXP (x
, 0), reg
, 0) != 0)
2557 return (rtx
) (HOST_WIDE_INT
) 1;
2561 return (rtx
) (HOST_WIDE_INT
) 1;
2563 for (i
= GET_RTX_LENGTH (code
) - 1; i
>= 0; i
--)
2567 tem
= find_use_as_address (XEXP (x
, i
), reg
, plusconst
);
2571 return (rtx
) (HOST_WIDE_INT
) 1;
2576 for (j
= XVECLEN (x
, i
) - 1; j
>= 0; j
--)
2578 tem
= find_use_as_address (XVECEXP (x
, i
, j
), reg
, plusconst
);
2582 return (rtx
) (HOST_WIDE_INT
) 1;
2590 /* Write information about registers and basic blocks into FILE.
2591 This is part of making a debugging dump. */
2594 dump_flow_info (file
)
2598 static char *reg_class_names
[] = REG_CLASS_NAMES
;
2600 fprintf (file
, "%d registers.\n", max_regno
);
2602 for (i
= FIRST_PSEUDO_REGISTER
; i
< max_regno
; i
++)
2605 enum reg_class
class, altclass
;
2606 fprintf (file
, "\nRegister %d used %d times across %d insns",
2607 i
, reg_n_refs
[i
], reg_live_length
[i
]);
2608 if (reg_basic_block
[i
] >= 0)
2609 fprintf (file
, " in block %d", reg_basic_block
[i
]);
2610 if (reg_n_deaths
[i
] != 1)
2611 fprintf (file
, "; dies in %d places", reg_n_deaths
[i
]);
2612 if (reg_n_calls_crossed
[i
] == 1)
2613 fprintf (file
, "; crosses 1 call");
2614 else if (reg_n_calls_crossed
[i
])
2615 fprintf (file
, "; crosses %d calls", reg_n_calls_crossed
[i
]);
2616 if (PSEUDO_REGNO_BYTES (i
) != UNITS_PER_WORD
)
2617 fprintf (file
, "; %d bytes", PSEUDO_REGNO_BYTES (i
));
2618 class = reg_preferred_class (i
);
2619 altclass
= reg_alternate_class (i
);
2620 if (class != GENERAL_REGS
|| altclass
!= ALL_REGS
)
2622 if (altclass
== ALL_REGS
|| class == ALL_REGS
)
2623 fprintf (file
, "; pref %s", reg_class_names
[(int) class]);
2624 else if (altclass
== NO_REGS
)
2625 fprintf (file
, "; %s or none", reg_class_names
[(int) class]);
2627 fprintf (file
, "; pref %s, else %s",
2628 reg_class_names
[(int) class],
2629 reg_class_names
[(int) altclass
]);
2631 if (REGNO_POINTER_FLAG (i
))
2632 fprintf (file
, "; pointer");
2633 fprintf (file
, ".\n");
2635 fprintf (file
, "\n%d basic blocks.\n", n_basic_blocks
);
2636 for (i
= 0; i
< n_basic_blocks
; i
++)
2638 register rtx head
, jump
;
2640 fprintf (file
, "\nBasic block %d: first insn %d, last %d.\n",
2642 INSN_UID (basic_block_head
[i
]),
2643 INSN_UID (basic_block_end
[i
]));
2644 /* The control flow graph's storage is freed
2645 now when flow_analysis returns.
2646 Don't try to print it if it is gone. */
2647 if (basic_block_drops_in
)
2649 fprintf (file
, "Reached from blocks: ");
2650 head
= basic_block_head
[i
];
2651 if (GET_CODE (head
) == CODE_LABEL
)
2652 for (jump
= LABEL_REFS (head
);
2654 jump
= LABEL_NEXTREF (jump
))
2656 register int from_block
= BLOCK_NUM (CONTAINING_INSN (jump
));
2657 fprintf (file
, " %d", from_block
);
2659 if (basic_block_drops_in
[i
])
2660 fprintf (file
, " previous");
2662 fprintf (file
, "\nRegisters live at start:");
2663 for (regno
= 0; regno
< max_regno
; regno
++)
2665 register int offset
= regno
/ REGSET_ELT_BITS
;
2666 register REGSET_ELT_TYPE bit
2667 = (REGSET_ELT_TYPE
) 1 << (regno
% REGSET_ELT_BITS
);
2668 if (basic_block_live_at_start
[i
][offset
] & bit
)
2669 fprintf (file
, " %d", regno
);
2671 fprintf (file
, "\n");
2673 fprintf (file
, "\n");