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 extern int xmalloc ();
127 /* List of labels that must never be deleted. */
128 extern rtx forced_labels
;
130 /* Get the basic block number of an insn.
131 This info should not be expected to remain available
132 after the end of life_analysis. */
134 /* This is the limit of the allocated space in the following two arrays. */
136 static int max_uid_for_flow
;
138 #define BLOCK_NUM(INSN) uid_block_number[INSN_UID (INSN)]
140 /* This is where the BLOCK_NUM values are really stored.
141 This is set up by find_basic_blocks and used there and in life_analysis,
144 static short *uid_block_number
;
146 /* INSN_VOLATILE (insn) is 1 if the insn refers to anything volatile. */
148 #define INSN_VOLATILE(INSN) uid_volatile[INSN_UID (INSN)]
149 static char *uid_volatile
;
151 /* Number of basic blocks in the current function. */
155 /* Maximum register number used in this function, plus one. */
159 /* Maximum number of SCRATCH rtx's used in any basic block of this function. */
163 /* Number of SCRATCH rtx's in the current block. */
165 static int num_scratch
;
167 /* Indexed by n, gives number of basic block that (REG n) is used in.
168 If the value is REG_BLOCK_GLOBAL (-2),
169 it means (REG n) is used in more than one basic block.
170 REG_BLOCK_UNKNOWN (-1) means it hasn't been seen yet so we don't know.
171 This information remains valid for the rest of the compilation
172 of the current function; it is used to control register allocation. */
174 short *reg_basic_block
;
176 /* Indexed by n, gives number of times (REG n) is used or set, each
177 weighted by its loop-depth.
178 This information remains valid for the rest of the compilation
179 of the current function; it is used to control register allocation. */
183 /* Indexed by N, gives number of places register N dies.
184 This information remains valid for the rest of the compilation
185 of the current function; it is used to control register allocation. */
189 /* Indexed by N, gives 1 if that reg is live across any CALL_INSNs.
190 This information remains valid for the rest of the compilation
191 of the current function; it is used to control register allocation. */
193 int *reg_n_calls_crossed
;
195 /* Total number of instructions at which (REG n) is live.
196 The larger this is, the less priority (REG n) gets for
197 allocation in a real register.
198 This information remains valid for the rest of the compilation
199 of the current function; it is used to control register allocation.
201 local-alloc.c may alter this number to change the priority.
203 Negative values are special.
204 -1 is used to mark a pseudo reg which has a constant or memory equivalent
205 and is used infrequently enough that it should not get a hard register.
206 -2 is used to mark a pseudo reg for a parameter, when a frame pointer
207 is not required. global-alloc.c makes an allocno for this but does
208 not try to assign a hard register to it. */
210 int *reg_live_length
;
212 /* Element N is the next insn that uses (hard or pseudo) register number N
213 within the current basic block; or zero, if there is no such insn.
214 This is valid only during the final backward scan in propagate_block. */
216 static rtx
*reg_next_use
;
218 /* Size of a regset for the current function,
219 in (1) bytes and (2) elements. */
224 /* Element N is first insn in basic block N.
225 This info lasts until we finish compiling the function. */
227 rtx
*basic_block_head
;
229 /* Element N is last insn in basic block N.
230 This info lasts until we finish compiling the function. */
232 rtx
*basic_block_end
;
234 /* Element N is a regset describing the registers live
235 at the start of basic block N.
236 This info lasts until we finish compiling the function. */
238 regset
*basic_block_live_at_start
;
240 /* Regset of regs live when calls to `setjmp'-like functions happen. */
242 regset regs_live_at_setjmp
;
244 /* List made of EXPR_LIST rtx's which gives pairs of pseudo registers
245 that have to go in the same hard reg.
246 The first two regs in the list are a pair, and the next two
247 are another pair, etc. */
250 /* Element N is nonzero if control can drop into basic block N
251 from the preceding basic block. Freed after life_analysis. */
253 static char *basic_block_drops_in
;
255 /* Element N is depth within loops of the last insn in basic block number N.
256 Freed after life_analysis. */
258 static short *basic_block_loop_depth
;
260 /* Element N nonzero if basic block N can actually be reached.
261 Vector exists only during find_basic_blocks. */
263 static char *block_live_static
;
265 /* Depth within loops of basic block being scanned for lifetime analysis,
266 plus one. This is the weight attached to references to registers. */
268 static int loop_depth
;
270 /* During propagate_block, this is non-zero if the value of CC0 is live. */
274 /* During propagate_block, this contains the last MEM stored into. It
275 is used to eliminate consecutive stores to the same location. */
277 static rtx last_mem_set
;
279 /* Set of registers that may be eliminable. These are handled specially
280 in updating regs_ever_live. */
282 static HARD_REG_SET elim_reg_set
;
284 /* Forward declarations */
285 static void find_basic_blocks ();
286 static void life_analysis ();
287 static void mark_label_ref ();
288 void allocate_for_life_analysis (); /* Used also in stupid_life_analysis */
289 static void init_regset_vector ();
290 static void propagate_block ();
291 static void mark_set_regs ();
292 static void mark_used_regs ();
293 static int insn_dead_p ();
294 static int libcall_dead_p ();
295 static int try_pre_increment ();
296 static int try_pre_increment_1 ();
297 static rtx
find_use_as_address ();
298 void dump_flow_info ();
300 /* Find basic blocks of the current function and perform data flow analysis.
301 F is the first insn of the function and NREGS the number of register numbers
305 flow_analysis (f
, nregs
, file
)
313 #ifdef ELIMINABLE_REGS
314 static struct {int from
, to
; } eliminables
[] = ELIMINABLE_REGS
;
317 /* Record which registers will be eliminated. We use this in
320 CLEAR_HARD_REG_SET (elim_reg_set
);
322 #ifdef ELIMINABLE_REGS
323 for (i
= 0; i
< sizeof eliminables
/ sizeof eliminables
[0]; i
++)
324 SET_HARD_REG_BIT (elim_reg_set
, eliminables
[i
].from
);
326 SET_HARD_REG_BIT (elim_reg_set
, FRAME_POINTER_REGNUM
);
329 /* Count the basic blocks. Also find maximum insn uid value used. */
332 register RTX_CODE prev_code
= JUMP_INSN
;
333 register RTX_CODE code
;
335 max_uid_for_flow
= 0;
337 for (insn
= f
, i
= 0; insn
; insn
= NEXT_INSN (insn
))
339 code
= GET_CODE (insn
);
340 if (INSN_UID (insn
) > max_uid_for_flow
)
341 max_uid_for_flow
= INSN_UID (insn
);
342 if (code
== CODE_LABEL
343 || (prev_code
!= INSN
&& prev_code
!= CALL_INSN
344 && prev_code
!= CODE_LABEL
345 && GET_RTX_CLASS (code
) == 'i'))
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
);
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. */
387 find_basic_blocks (f
)
392 register char *block_live
= (char *) alloca (n_basic_blocks
);
393 register char *block_marked
= (char *) alloca (n_basic_blocks
);
394 /* List of label_refs to all labels whose addresses are taken
396 rtx label_value_list
= 0;
398 block_live_static
= block_live
;
399 bzero (block_live
, n_basic_blocks
);
400 bzero (block_marked
, n_basic_blocks
);
402 /* Initialize with just block 0 reachable and no blocks marked. */
403 if (n_basic_blocks
> 0)
406 /* Initialize the ref chain of each label to 0. */
407 /* Record where all the blocks start and end and their depth in loops. */
408 /* For each insn, record the block it is in. */
409 /* Also mark as reachable any blocks headed by labels that
410 must not be deleted. */
413 register RTX_CODE prev_code
= JUMP_INSN
;
414 register RTX_CODE code
;
417 for (insn
= f
, i
= -1; insn
; insn
= NEXT_INSN (insn
))
419 code
= GET_CODE (insn
);
422 if (NOTE_LINE_NUMBER (insn
) == NOTE_INSN_LOOP_BEG
)
424 else if (NOTE_LINE_NUMBER (insn
) == NOTE_INSN_LOOP_END
)
427 else if (code
== CODE_LABEL
428 || (prev_code
!= INSN
&& prev_code
!= CALL_INSN
429 && prev_code
!= CODE_LABEL
430 && GET_RTX_CLASS (code
) == 'i'))
432 basic_block_head
[++i
] = insn
;
433 basic_block_end
[i
] = insn
;
434 basic_block_loop_depth
[i
] = depth
;
435 if (code
== CODE_LABEL
)
437 LABEL_REFS (insn
) = insn
;
438 /* Any label that cannot be deleted
439 is considered to start a reachable block. */
440 if (LABEL_PRESERVE_P (insn
))
444 else if (GET_RTX_CLASS (code
) == 'i')
446 basic_block_end
[i
] = insn
;
447 basic_block_loop_depth
[i
] = depth
;
450 /* Make a list of all labels referred to other than by jumps. */
451 if (code
== INSN
|| code
== CALL_INSN
)
453 rtx note
= find_reg_note (insn
, REG_LABEL
, 0);
455 label_value_list
= gen_rtx (EXPR_LIST
, VOIDmode
, XEXP (note
, 0),
459 BLOCK_NUM (insn
) = i
;
463 if (i
+ 1 != n_basic_blocks
)
467 /* Record which basic blocks control can drop in to. */
471 for (i
= 0; i
< n_basic_blocks
; i
++)
473 register rtx insn
= PREV_INSN (basic_block_head
[i
]);
474 /* TEMP1 is used to avoid a bug in Sequent's compiler. */
476 while (insn
&& GET_CODE (insn
) == NOTE
)
477 insn
= PREV_INSN (insn
);
478 temp1
= insn
&& GET_CODE (insn
) != BARRIER
;
479 basic_block_drops_in
[i
] = temp1
;
483 /* Now find which basic blocks can actually be reached
484 and put all jump insns' LABEL_REFS onto the ref-chains
485 of their target labels. */
487 if (n_basic_blocks
> 0)
489 int something_marked
= 1;
491 /* Find all indirect jump insns and mark them as possibly jumping
492 to all the labels whose addresses are explicitly used.
493 This is because, when there are computed gotos,
494 we can't tell which labels they jump to, of all the possibilities. */
496 for (insn
= f
; insn
; insn
= NEXT_INSN (insn
))
497 if (GET_CODE (insn
) == JUMP_INSN
498 && GET_CODE (PATTERN (insn
)) == SET
499 && SET_DEST (PATTERN (insn
)) == pc_rtx
500 && GET_CODE (SET_SRC (PATTERN (insn
))) == REG
)
503 for (x
= label_value_list
; x
; x
= XEXP (x
, 1))
504 mark_label_ref (gen_rtx (LABEL_REF
, VOIDmode
, XEXP (x
, 0)),
506 for (x
= forced_labels
; x
; x
= XEXP (x
, 1))
507 mark_label_ref (gen_rtx (LABEL_REF
, VOIDmode
, XEXP (x
, 0)),
511 /* Pass over all blocks, marking each block that is reachable
512 and has not yet been marked.
513 Keep doing this until, in one pass, no blocks have been marked.
514 Then blocks_live and blocks_marked are identical and correct.
515 In addition, all jumps actually reachable have been marked. */
517 while (something_marked
)
519 something_marked
= 0;
520 for (i
= 0; i
< n_basic_blocks
; i
++)
521 if (block_live
[i
] && !block_marked
[i
])
524 something_marked
= 1;
525 if (i
+ 1 < n_basic_blocks
&& basic_block_drops_in
[i
+ 1])
526 block_live
[i
+ 1] = 1;
527 insn
= basic_block_end
[i
];
528 if (GET_CODE (insn
) == JUMP_INSN
)
529 mark_label_ref (PATTERN (insn
), insn
, 0);
533 /* Now delete the code for any basic blocks that can't be reached.
534 They can occur because jump_optimize does not recognize
535 unreachable loops as unreachable. */
537 for (i
= 0; i
< n_basic_blocks
; i
++)
540 insn
= basic_block_head
[i
];
543 if (GET_CODE (insn
) == BARRIER
)
545 if (GET_CODE (insn
) != NOTE
)
547 PUT_CODE (insn
, NOTE
);
548 NOTE_LINE_NUMBER (insn
) = NOTE_INSN_DELETED
;
549 NOTE_SOURCE_FILE (insn
) = 0;
551 if (insn
== basic_block_end
[i
])
553 /* BARRIERs are between basic blocks, not part of one.
554 Delete a BARRIER if the preceding jump is deleted.
555 We cannot alter a BARRIER into a NOTE
556 because it is too short; but we can really delete
557 it because it is not part of a basic block. */
558 if (NEXT_INSN (insn
) != 0
559 && GET_CODE (NEXT_INSN (insn
)) == BARRIER
)
560 delete_insn (NEXT_INSN (insn
));
563 insn
= NEXT_INSN (insn
);
565 /* Each time we delete some basic blocks,
566 see if there is a jump around them that is
567 being turned into a no-op. If so, delete it. */
569 if (block_live
[i
- 1])
572 for (j
= i
; j
< n_basic_blocks
; j
++)
576 insn
= basic_block_end
[i
- 1];
577 if (GET_CODE (insn
) == JUMP_INSN
578 /* An unconditional jump is the only possibility
579 we must check for, since a conditional one
580 would make these blocks live. */
581 && simplejump_p (insn
)
582 && (label
= XEXP (SET_SRC (PATTERN (insn
)), 0), 1)
583 && INSN_UID (label
) != 0
584 && BLOCK_NUM (label
) == j
)
586 PUT_CODE (insn
, NOTE
);
587 NOTE_LINE_NUMBER (insn
) = NOTE_INSN_DELETED
;
588 NOTE_SOURCE_FILE (insn
) = 0;
589 if (GET_CODE (NEXT_INSN (insn
)) != BARRIER
)
591 delete_insn (NEXT_INSN (insn
));
600 /* Check expression X for label references;
601 if one is found, add INSN to the label's chain of references.
603 CHECKDUP means check for and avoid creating duplicate references
604 from the same insn. Such duplicates do no serious harm but
605 can slow life analysis. CHECKDUP is set only when duplicates
609 mark_label_ref (x
, insn
, checkdup
)
613 register RTX_CODE code
;
617 /* We can be called with NULL when scanning label_value_list. */
622 if (code
== LABEL_REF
)
624 register rtx label
= XEXP (x
, 0);
626 if (GET_CODE (label
) != CODE_LABEL
)
628 /* If the label was never emitted, this insn is junk,
629 but avoid a crash trying to refer to BLOCK_NUM (label).
630 This can happen as a result of a syntax error
631 and a diagnostic has already been printed. */
632 if (INSN_UID (label
) == 0)
634 CONTAINING_INSN (x
) = insn
;
635 /* if CHECKDUP is set, check for duplicate ref from same insn
638 for (y
= LABEL_REFS (label
); y
!= label
; y
= LABEL_NEXTREF (y
))
639 if (CONTAINING_INSN (y
) == insn
)
641 LABEL_NEXTREF (x
) = LABEL_REFS (label
);
642 LABEL_REFS (label
) = x
;
643 block_live_static
[BLOCK_NUM (label
)] = 1;
647 fmt
= GET_RTX_FORMAT (code
);
648 for (i
= GET_RTX_LENGTH (code
) - 1; i
>= 0; i
--)
651 mark_label_ref (XEXP (x
, i
), insn
, 0);
655 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
656 mark_label_ref (XVECEXP (x
, i
, j
), insn
, 1);
661 /* Determine which registers are live at the start of each
662 basic block of the function whose first insn is F.
663 NREGS is the number of registers used in F.
664 We allocate the vector basic_block_live_at_start
665 and the regsets that it points to, and fill them with the data.
666 regset_size and regset_bytes are also set here. */
669 life_analysis (f
, nregs
)
676 /* For each basic block, a bitmask of regs
677 live on exit from the block. */
678 regset
*basic_block_live_at_end
;
679 /* For each basic block, a bitmask of regs
680 live on entry to a successor-block of this block.
681 If this does not match basic_block_live_at_end,
682 that must be updated, and the block must be rescanned. */
683 regset
*basic_block_new_live_at_end
;
684 /* For each basic block, a bitmask of regs
685 whose liveness at the end of the basic block
686 can make a difference in which regs are live on entry to the block.
687 These are the regs that are set within the basic block,
688 possibly excluding those that are used after they are set. */
689 regset
*basic_block_significant
;
693 struct obstack flow_obstack
;
695 gcc_obstack_init (&flow_obstack
);
699 bzero (regs_ever_live
, sizeof regs_ever_live
);
701 /* Allocate and zero out many data structures
702 that will record the data from lifetime analysis. */
704 allocate_for_life_analysis ();
706 reg_next_use
= (rtx
*) alloca (nregs
* sizeof (rtx
));
707 bzero (reg_next_use
, nregs
* sizeof (rtx
));
709 /* Set up several regset-vectors used internally within this function.
710 Their meanings are documented above, with their declarations. */
712 basic_block_live_at_end
= (regset
*) alloca (n_basic_blocks
* sizeof (regset
));
713 /* Don't use alloca since that leads to a crash rather than an error message
714 if there isn't enough space.
715 Don't use oballoc since we may need to allocate other things during
716 this function on the temporary obstack. */
717 tem
= (regset
) obstack_alloc (&flow_obstack
, n_basic_blocks
* regset_bytes
);
718 bzero (tem
, n_basic_blocks
* regset_bytes
);
719 init_regset_vector (basic_block_live_at_end
, tem
, n_basic_blocks
, regset_bytes
);
721 basic_block_new_live_at_end
= (regset
*) alloca (n_basic_blocks
* sizeof (regset
));
722 tem
= (regset
) obstack_alloc (&flow_obstack
, n_basic_blocks
* regset_bytes
);
723 bzero (tem
, n_basic_blocks
* regset_bytes
);
724 init_regset_vector (basic_block_new_live_at_end
, tem
, n_basic_blocks
, regset_bytes
);
726 basic_block_significant
= (regset
*) alloca (n_basic_blocks
* sizeof (regset
));
727 tem
= (regset
) obstack_alloc (&flow_obstack
, n_basic_blocks
* regset_bytes
);
728 bzero (tem
, n_basic_blocks
* regset_bytes
);
729 init_regset_vector (basic_block_significant
, tem
, n_basic_blocks
, regset_bytes
);
731 /* Record which insns refer to any volatile memory
732 or for any reason can't be deleted just because they are dead stores.
733 Also, delete any insns that copy a register to itself. */
735 for (insn
= f
; insn
; insn
= NEXT_INSN (insn
))
737 enum rtx_code code1
= GET_CODE (insn
);
738 if (code1
== CALL_INSN
)
739 INSN_VOLATILE (insn
) = 1;
740 else if (code1
== INSN
|| code1
== JUMP_INSN
)
742 /* Delete (in effect) any obvious no-op moves. */
743 if (GET_CODE (PATTERN (insn
)) == SET
744 && GET_CODE (SET_DEST (PATTERN (insn
))) == REG
745 && GET_CODE (SET_SRC (PATTERN (insn
))) == REG
746 && REGNO (SET_DEST (PATTERN (insn
))) ==
747 REGNO (SET_SRC (PATTERN (insn
)))
748 /* Insns carrying these notes are useful later on. */
749 && ! find_reg_note (insn
, REG_EQUAL
, 0))
751 PUT_CODE (insn
, NOTE
);
752 NOTE_LINE_NUMBER (insn
) = NOTE_INSN_DELETED
;
753 NOTE_SOURCE_FILE (insn
) = 0;
755 else if (GET_CODE (PATTERN (insn
)) == PARALLEL
)
757 /* If nothing but SETs of registers to themselves,
758 this insn can also be deleted. */
759 for (i
= 0; i
< XVECLEN (PATTERN (insn
), 0); i
++)
761 rtx tem
= XVECEXP (PATTERN (insn
), 0, i
);
763 if (GET_CODE (tem
) == USE
764 || GET_CODE (tem
) == CLOBBER
)
767 if (GET_CODE (tem
) != SET
768 || GET_CODE (SET_DEST (tem
)) != REG
769 || GET_CODE (SET_SRC (tem
)) != REG
770 || REGNO (SET_DEST (tem
)) != REGNO (SET_SRC (tem
)))
774 if (i
== XVECLEN (PATTERN (insn
), 0)
775 /* Insns carrying these notes are useful later on. */
776 && ! find_reg_note (insn
, REG_EQUAL
, 0))
778 PUT_CODE (insn
, NOTE
);
779 NOTE_LINE_NUMBER (insn
) = NOTE_INSN_DELETED
;
780 NOTE_SOURCE_FILE (insn
) = 0;
783 INSN_VOLATILE (insn
) = volatile_refs_p (PATTERN (insn
));
785 else if (GET_CODE (PATTERN (insn
)) != USE
)
786 INSN_VOLATILE (insn
) = volatile_refs_p (PATTERN (insn
));
787 /* A SET that makes space on the stack cannot be dead.
788 (Such SETs occur only for allocating variable-size data,
789 so they will always have a PLUS or MINUS according to the
790 direction of stack growth.)
791 Even if this function never uses this stack pointer value,
792 signal handlers do! */
793 else if (code1
== INSN
&& GET_CODE (PATTERN (insn
)) == SET
794 && SET_DEST (PATTERN (insn
)) == stack_pointer_rtx
795 #ifdef STACK_GROWS_DOWNWARD
796 && GET_CODE (SET_SRC (PATTERN (insn
))) == MINUS
798 && GET_CODE (SET_SRC (PATTERN (insn
))) == PLUS
800 && XEXP (SET_SRC (PATTERN (insn
)), 0) == stack_pointer_rtx
)
801 INSN_VOLATILE (insn
) = 1;
805 if (n_basic_blocks
> 0)
806 #ifdef EXIT_IGNORE_STACK
807 if (! EXIT_IGNORE_STACK
808 || (! FRAME_POINTER_REQUIRED
&& flag_omit_frame_pointer
))
811 /* If exiting needs the right stack value,
812 consider the stack pointer live at the end of the function. */
813 basic_block_live_at_end
[n_basic_blocks
- 1]
814 [STACK_POINTER_REGNUM
/ REGSET_ELT_BITS
]
815 |= 1 << (STACK_POINTER_REGNUM
% REGSET_ELT_BITS
);
816 basic_block_new_live_at_end
[n_basic_blocks
- 1]
817 [STACK_POINTER_REGNUM
/ REGSET_ELT_BITS
]
818 |= 1 << (STACK_POINTER_REGNUM
% REGSET_ELT_BITS
);
821 /* Mark all global registers as being live at the end of the function
822 since they may be referenced by our caller. */
824 if (n_basic_blocks
> 0)
825 for (i
= 0; i
< FIRST_PSEUDO_REGISTER
; i
++)
828 basic_block_live_at_end
[n_basic_blocks
- 1]
829 [i
/ REGSET_ELT_BITS
] |= 1 << (i
% REGSET_ELT_BITS
);
830 basic_block_new_live_at_end
[n_basic_blocks
- 1]
831 [i
/ REGSET_ELT_BITS
] |= 1 << (i
% REGSET_ELT_BITS
);
834 /* Propagate life info through the basic blocks
835 around the graph of basic blocks.
837 This is a relaxation process: each time a new register
838 is live at the end of the basic block, we must scan the block
839 to determine which registers are, as a consequence, live at the beginning
840 of that block. These registers must then be marked live at the ends
841 of all the blocks that can transfer control to that block.
842 The process continues until it reaches a fixed point. */
849 for (i
= n_basic_blocks
- 1; i
>= 0; i
--)
851 int consider
= first_pass
;
852 int must_rescan
= first_pass
;
857 /* Set CONSIDER if this block needs thinking about at all
858 (that is, if the regs live now at the end of it
859 are not the same as were live at the end of it when
860 we last thought about it).
861 Set must_rescan if it needs to be thought about
862 instruction by instruction (that is, if any additional
863 reg that is live at the end now but was not live there before
864 is one of the significant regs of this basic block). */
866 for (j
= 0; j
< regset_size
; j
++)
868 register int x
= (basic_block_new_live_at_end
[i
][j
]
869 & ~basic_block_live_at_end
[i
][j
]);
872 if (x
& basic_block_significant
[i
][j
])
884 /* The live_at_start of this block may be changing,
885 so another pass will be required after this one. */
890 /* No complete rescan needed;
891 just record those variables newly known live at end
892 as live at start as well. */
893 for (j
= 0; j
< regset_size
; j
++)
895 register int x
= basic_block_new_live_at_end
[i
][j
]
896 & ~basic_block_live_at_end
[i
][j
];
897 basic_block_live_at_start
[i
][j
] |= x
;
898 basic_block_live_at_end
[i
][j
] |= x
;
903 /* Update the basic_block_live_at_start
904 by propagation backwards through the block. */
905 bcopy (basic_block_new_live_at_end
[i
],
906 basic_block_live_at_end
[i
], regset_bytes
);
907 bcopy (basic_block_live_at_end
[i
],
908 basic_block_live_at_start
[i
], regset_bytes
);
909 propagate_block (basic_block_live_at_start
[i
],
910 basic_block_head
[i
], basic_block_end
[i
], 0,
911 first_pass
? basic_block_significant
[i
] : 0,
916 register rtx jump
, head
;
917 /* Update the basic_block_new_live_at_end's of the block
918 that falls through into this one (if any). */
919 head
= basic_block_head
[i
];
920 jump
= PREV_INSN (head
);
921 if (basic_block_drops_in
[i
])
923 register int from_block
= BLOCK_NUM (jump
);
925 for (j
= 0; j
< regset_size
; j
++)
926 basic_block_new_live_at_end
[from_block
][j
]
927 |= basic_block_live_at_start
[i
][j
];
929 /* Update the basic_block_new_live_at_end's of
930 all the blocks that jump to this one. */
931 if (GET_CODE (head
) == CODE_LABEL
)
932 for (jump
= LABEL_REFS (head
);
934 jump
= LABEL_NEXTREF (jump
))
936 register int from_block
= BLOCK_NUM (CONTAINING_INSN (jump
));
938 for (j
= 0; j
< regset_size
; j
++)
939 basic_block_new_live_at_end
[from_block
][j
]
940 |= basic_block_live_at_start
[i
][j
];
950 /* The only pseudos that are live at the beginning of the function are
951 those that were not set anywhere in the function. local-alloc doesn't
952 know how to handle these correctly, so mark them as not local to any
955 if (n_basic_blocks
> 0)
956 for (i
= FIRST_PSEUDO_REGISTER
; i
< max_regno
; i
++)
957 if (basic_block_live_at_start
[0][i
/ REGSET_ELT_BITS
]
958 & (1 << (i
% REGSET_ELT_BITS
)))
959 reg_basic_block
[i
] = REG_BLOCK_GLOBAL
;
961 /* Now the life information is accurate.
962 Make one more pass over each basic block
963 to delete dead stores, create autoincrement addressing
964 and record how many times each register is used, is set, or dies.
966 To save time, we operate directly in basic_block_live_at_end[i],
967 thus destroying it (in fact, converting it into a copy of
968 basic_block_live_at_start[i]). This is ok now because
969 basic_block_live_at_end[i] is no longer used past this point. */
973 for (i
= 0; i
< n_basic_blocks
; i
++)
975 propagate_block (basic_block_live_at_end
[i
],
976 basic_block_head
[i
], basic_block_end
[i
], 1, 0, i
);
983 /* Something live during a setjmp should not be put in a register
984 on certain machines which restore regs from stack frames
985 rather than from the jmpbuf.
986 But we don't need to do this for the user's variables, since
987 ANSI says only volatile variables need this. */
988 #ifdef LONGJMP_RESTORE_FROM_STACK
989 for (i
= FIRST_PSEUDO_REGISTER
; i
< nregs
; i
++)
990 if (regs_live_at_setjmp
[i
/ REGSET_ELT_BITS
] & (1 << (i
% REGSET_ELT_BITS
))
991 && regno_reg_rtx
[i
] != 0 && ! REG_USERVAR_P (regno_reg_rtx
[i
]))
993 reg_live_length
[i
] = -1;
994 reg_basic_block
[i
] = -1;
999 /* We have a problem with any pseudoreg that
1000 lives across the setjmp. ANSI says that if a
1001 user variable does not change in value
1002 between the setjmp and the longjmp, then the longjmp preserves it.
1003 This includes longjmp from a place where the pseudo appears dead.
1004 (In principle, the value still exists if it is in scope.)
1005 If the pseudo goes in a hard reg, some other value may occupy
1006 that hard reg where this pseudo is dead, thus clobbering the pseudo.
1007 Conclusion: such a pseudo must not go in a hard reg. */
1008 for (i
= FIRST_PSEUDO_REGISTER
; i
< nregs
; i
++)
1009 if (regs_live_at_setjmp
[i
/ REGSET_ELT_BITS
] & (1 << (i
% REGSET_ELT_BITS
))
1010 && regno_reg_rtx
[i
] != 0)
1012 reg_live_length
[i
] = -1;
1013 reg_basic_block
[i
] = -1;
1016 obstack_free (&flow_obstack
, 0);
1019 /* Subroutines of life analysis. */
1021 /* Allocate the permanent data structures that represent the results
1022 of life analysis. Not static since used also for stupid life analysis. */
1025 allocate_for_life_analysis ()
1028 register regset tem
;
1030 regset_size
= ((max_regno
+ REGSET_ELT_BITS
- 1) / REGSET_ELT_BITS
);
1031 regset_bytes
= regset_size
* sizeof (*(regset
)0);
1033 reg_n_refs
= (int *) oballoc (max_regno
* sizeof (int));
1034 bzero (reg_n_refs
, max_regno
* sizeof (int));
1036 reg_n_sets
= (short *) oballoc (max_regno
* sizeof (short));
1037 bzero (reg_n_sets
, max_regno
* sizeof (short));
1039 reg_n_deaths
= (short *) oballoc (max_regno
* sizeof (short));
1040 bzero (reg_n_deaths
, max_regno
* sizeof (short));
1042 reg_live_length
= (int *) oballoc (max_regno
* sizeof (int));
1043 bzero (reg_live_length
, max_regno
* sizeof (int));
1045 reg_n_calls_crossed
= (int *) oballoc (max_regno
* sizeof (int));
1046 bzero (reg_n_calls_crossed
, max_regno
* sizeof (int));
1048 reg_basic_block
= (short *) oballoc (max_regno
* sizeof (short));
1049 for (i
= 0; i
< max_regno
; i
++)
1050 reg_basic_block
[i
] = REG_BLOCK_UNKNOWN
;
1052 basic_block_live_at_start
= (regset
*) oballoc (n_basic_blocks
* sizeof (regset
));
1053 tem
= (regset
) oballoc (n_basic_blocks
* regset_bytes
);
1054 bzero (tem
, n_basic_blocks
* regset_bytes
);
1055 init_regset_vector (basic_block_live_at_start
, tem
, n_basic_blocks
, regset_bytes
);
1057 regs_live_at_setjmp
= (regset
) oballoc (regset_bytes
);
1058 bzero (regs_live_at_setjmp
, regset_bytes
);
1061 /* Make each element of VECTOR point at a regset,
1062 taking the space for all those regsets from SPACE.
1063 SPACE is of type regset, but it is really as long as NELTS regsets.
1064 BYTES_PER_ELT is the number of bytes in one regset. */
1067 init_regset_vector (vector
, space
, nelts
, bytes_per_elt
)
1074 register regset p
= space
;
1076 for (i
= 0; i
< nelts
; i
++)
1079 p
+= bytes_per_elt
/ sizeof (*p
);
1083 /* Compute the registers live at the beginning of a basic block
1084 from those live at the end.
1086 When called, OLD contains those live at the end.
1087 On return, it contains those live at the beginning.
1088 FIRST and LAST are the first and last insns of the basic block.
1090 FINAL is nonzero if we are doing the final pass which is not
1091 for computing the life info (since that has already been done)
1092 but for acting on it. On this pass, we delete dead stores,
1093 set up the logical links and dead-variables lists of instructions,
1094 and merge instructions for autoincrement and autodecrement addresses.
1096 SIGNIFICANT is nonzero only the first time for each basic block.
1097 If it is nonzero, it points to a regset in which we store
1098 a 1 for each register that is set within the block.
1100 BNUM is the number of the basic block. */
1103 propagate_block (old
, first
, last
, final
, significant
, bnum
)
1104 register regset old
;
1116 /* The following variables are used only if FINAL is nonzero. */
1117 /* This vector gets one element for each reg that has been live
1118 at any point in the basic block that has been scanned so far.
1119 SOMETIMES_MAX says how many elements are in use so far.
1120 In each element, OFFSET is the byte-number within a regset
1121 for the register described by the element, and BIT is a mask
1122 for that register's bit within the byte. */
1123 register struct foo
{ short offset
; short bit
; } *regs_sometimes_live
;
1124 int sometimes_max
= 0;
1125 /* This regset has 1 for each reg that we have seen live so far.
1126 It and REGS_SOMETIMES_LIVE are updated together. */
1129 /* The loop depth may change in the middle of a basic block. Since we
1130 scan from end to beginning, we start with the depth at the end of the
1131 current basic block, and adjust as we pass ends and starts of loops. */
1132 loop_depth
= basic_block_loop_depth
[bnum
];
1134 dead
= (regset
) alloca (regset_bytes
);
1135 live
= (regset
) alloca (regset_bytes
);
1140 /* Include any notes at the end of the block in the scan.
1141 This is in case the block ends with a call to setjmp. */
1143 while (NEXT_INSN (last
) != 0 && GET_CODE (NEXT_INSN (last
)) == NOTE
)
1145 /* Look for loop boundaries, we are going forward here. */
1146 last
= NEXT_INSN (last
);
1147 if (NOTE_LINE_NUMBER (last
) == NOTE_INSN_LOOP_BEG
)
1149 else if (NOTE_LINE_NUMBER (last
) == NOTE_INSN_LOOP_END
)
1155 register int i
, offset
, bit
;
1158 maxlive
= (regset
) alloca (regset_bytes
);
1159 bcopy (old
, maxlive
, regset_bytes
);
1161 = (struct foo
*) alloca (max_regno
* sizeof (struct foo
));
1163 /* Process the regs live at the end of the block.
1164 Enter them in MAXLIVE and REGS_SOMETIMES_LIVE.
1165 Also mark them as not local to any one basic block. */
1167 for (offset
= 0, i
= 0; offset
< regset_size
; offset
++)
1168 for (bit
= 1; bit
; bit
<<= 1, i
++)
1172 if (old
[offset
] & bit
)
1174 reg_basic_block
[i
] = REG_BLOCK_GLOBAL
;
1175 regs_sometimes_live
[sometimes_max
].offset
= offset
;
1176 regs_sometimes_live
[sometimes_max
].bit
= i
% REGSET_ELT_BITS
;
1182 /* Scan the block an insn at a time from end to beginning. */
1184 for (insn
= last
; ; insn
= prev
)
1186 prev
= PREV_INSN (insn
);
1188 /* Look for loop boundaries, remembering that we are going backwards. */
1189 if (GET_CODE (insn
) == NOTE
1190 && NOTE_LINE_NUMBER (insn
) == NOTE_INSN_LOOP_END
)
1192 else if (GET_CODE (insn
) == NOTE
1193 && NOTE_LINE_NUMBER (insn
) == NOTE_INSN_LOOP_BEG
)
1196 /* If we have LOOP_DEPTH == 0, there has been a bookkeeping error.
1197 Abort now rather than setting register status incorrectly. */
1198 if (loop_depth
== 0)
1201 /* If this is a call to `setjmp' et al,
1202 warn if any non-volatile datum is live. */
1204 if (final
&& GET_CODE (insn
) == NOTE
1205 && NOTE_LINE_NUMBER (insn
) == NOTE_INSN_SETJMP
)
1208 for (i
= 0; i
< regset_size
; i
++)
1209 regs_live_at_setjmp
[i
] |= old
[i
];
1212 /* Update the life-status of regs for this insn.
1213 First DEAD gets which regs are set in this insn
1214 then LIVE gets which regs are used in this insn.
1215 Then the regs live before the insn
1216 are those live after, with DEAD regs turned off,
1217 and then LIVE regs turned on. */
1219 if (GET_RTX_CLASS (GET_CODE (insn
)) == 'i')
1222 rtx note
= find_reg_note (insn
, REG_RETVAL
, 0);
1224 = (insn_dead_p (PATTERN (insn
), old
, 0)
1225 /* Don't delete something that refers to volatile storage! */
1226 && ! INSN_VOLATILE (insn
));
1228 = (insn_is_dead
&& note
!= 0
1229 && libcall_dead_p (PATTERN (insn
), old
, note
, insn
));
1231 /* If an instruction consists of just dead store(s) on final pass,
1232 "delete" it by turning it into a NOTE of type NOTE_INSN_DELETED.
1233 We could really delete it with delete_insn, but that
1234 can cause trouble for first or last insn in a basic block. */
1235 if (final
&& insn_is_dead
)
1237 PUT_CODE (insn
, NOTE
);
1238 NOTE_LINE_NUMBER (insn
) = NOTE_INSN_DELETED
;
1239 NOTE_SOURCE_FILE (insn
) = 0;
1241 /* If this insn is copying the return value from a library call,
1242 delete the entire library call. */
1243 if (libcall_is_dead
)
1245 rtx first
= XEXP (note
, 0);
1247 while (INSN_DELETED_P (first
))
1248 first
= NEXT_INSN (first
);
1253 NOTE_LINE_NUMBER (p
) = NOTE_INSN_DELETED
;
1254 NOTE_SOURCE_FILE (p
) = 0;
1260 for (i
= 0; i
< regset_size
; i
++)
1262 dead
[i
] = 0; /* Faster than bzero here */
1263 live
[i
] = 0; /* since regset_size is usually small */
1266 /* See if this is an increment or decrement that can be
1267 merged into a following memory address. */
1270 register rtx x
= PATTERN (insn
);
1271 /* Does this instruction increment or decrement a register? */
1272 if (final
&& GET_CODE (x
) == SET
1273 && GET_CODE (SET_DEST (x
)) == REG
1274 && (GET_CODE (SET_SRC (x
)) == PLUS
1275 || GET_CODE (SET_SRC (x
)) == MINUS
)
1276 && XEXP (SET_SRC (x
), 0) == SET_DEST (x
)
1277 && GET_CODE (XEXP (SET_SRC (x
), 1)) == CONST_INT
1278 /* Ok, look for a following memory ref we can combine with.
1279 If one is found, change the memory ref to a PRE_INC
1280 or PRE_DEC, cancel this insn, and return 1.
1281 Return 0 if nothing has been done. */
1282 && try_pre_increment_1 (insn
))
1285 #endif /* AUTO_INC_DEC */
1287 /* If this is not the final pass, and this insn is copying the
1288 value of a library call and it's dead, don't scan the
1289 insns that perform the library call, so that the call's
1290 arguments are not marked live. */
1291 if (libcall_is_dead
)
1293 /* Mark the dest reg as `significant'. */
1294 mark_set_regs (old
, dead
, PATTERN (insn
), 0, significant
);
1296 insn
= XEXP (note
, 0);
1297 prev
= PREV_INSN (insn
);
1299 else if (GET_CODE (PATTERN (insn
)) == SET
1300 && SET_DEST (PATTERN (insn
)) == stack_pointer_rtx
1301 && GET_CODE (SET_SRC (PATTERN (insn
))) == PLUS
1302 && XEXP (SET_SRC (PATTERN (insn
)), 0) == stack_pointer_rtx
1303 && GET_CODE (XEXP (SET_SRC (PATTERN (insn
)), 1)) == CONST_INT
)
1304 /* We have an insn to pop a constant amount off the stack.
1305 (Such insns use PLUS regardless of the direction of the stack,
1306 and any insn to adjust the stack by a constant is always a pop.)
1307 These insns, if not dead stores, have no effect on life. */
1311 /* LIVE gets the regs used in INSN;
1312 DEAD gets those set by it. Dead insns don't make anything
1315 mark_set_regs (old
, dead
, PATTERN (insn
), final
? insn
: 0,
1318 /* If an insn doesn't use CC0, it becomes dead since we
1319 assume that every insn clobbers it. So show it dead here;
1320 mark_used_regs will set it live if it is referenced. */
1324 mark_used_regs (old
, live
, PATTERN (insn
), final
, insn
);
1326 /* Sometimes we may have inserted something before INSN (such as
1327 a move) when we make an auto-inc. So ensure we will scan
1330 prev
= PREV_INSN (insn
);
1333 if (! insn_is_dead
&& GET_CODE (insn
) == CALL_INSN
)
1337 /* Each call clobbers all call-clobbered regs that are not
1338 global. Note that the function-value reg is a
1339 call-clobbered reg, and mark_set_regs has already had
1340 a chance to handle it. */
1342 for (i
= 0; i
< FIRST_PSEUDO_REGISTER
; i
++)
1343 if (call_used_regs
[i
] && ! global_regs
[i
])
1344 dead
[i
/ REGSET_ELT_BITS
]
1345 |= (1 << (i
% REGSET_ELT_BITS
));
1347 /* The stack ptr is used (honorarily) by a CALL insn. */
1348 live
[STACK_POINTER_REGNUM
/ REGSET_ELT_BITS
]
1349 |= (1 << (STACK_POINTER_REGNUM
% REGSET_ELT_BITS
));
1351 /* Calls may also reference any of the global registers,
1352 so they are made live. */
1354 for (i
= 0; i
< FIRST_PSEUDO_REGISTER
; i
++)
1356 live
[i
/ REGSET_ELT_BITS
]
1357 |= (1 << (i
% REGSET_ELT_BITS
));
1359 /* Calls also clobber memory. */
1363 /* Update OLD for the registers used or set. */
1364 for (i
= 0; i
< regset_size
; i
++)
1370 if (GET_CODE (insn
) == CALL_INSN
&& final
)
1372 /* Any regs live at the time of a call instruction
1373 must not go in a register clobbered by calls.
1374 Find all regs now live and record this for them. */
1376 register struct foo
*p
= regs_sometimes_live
;
1378 for (i
= 0; i
< sometimes_max
; i
++, p
++)
1379 if (old
[p
->offset
] & (1 << p
->bit
))
1380 reg_n_calls_crossed
[p
->offset
* REGSET_ELT_BITS
+ p
->bit
]+= 1;
1384 /* On final pass, add any additional sometimes-live regs
1385 into MAXLIVE and REGS_SOMETIMES_LIVE.
1386 Also update counts of how many insns each reg is live at. */
1390 for (i
= 0; i
< regset_size
; i
++)
1392 register int diff
= live
[i
] & ~maxlive
[i
];
1398 for (regno
= 0; diff
&& regno
< REGSET_ELT_BITS
; regno
++)
1399 if (diff
& (1 << regno
))
1401 regs_sometimes_live
[sometimes_max
].offset
= i
;
1402 regs_sometimes_live
[sometimes_max
].bit
= regno
;
1403 diff
&= ~ (1 << regno
);
1410 register struct foo
*p
= regs_sometimes_live
;
1411 for (i
= 0; i
< sometimes_max
; i
++, p
++)
1413 if (old
[p
->offset
] & (1 << p
->bit
))
1414 reg_live_length
[p
->offset
* REGSET_ELT_BITS
+ p
->bit
]++;
1424 if (num_scratch
> max_scratch
)
1425 max_scratch
= num_scratch
;
1428 /* Return 1 if X (the body of an insn, or part of it) is just dead stores
1429 (SET expressions whose destinations are registers dead after the insn).
1430 NEEDED is the regset that says which regs are alive after the insn.
1432 Unless CALL_OK is non-zero, an insn is needed if it contains a CALL. */
1435 insn_dead_p (x
, needed
, call_ok
)
1440 register RTX_CODE code
= GET_CODE (x
);
1441 /* If setting something that's a reg or part of one,
1442 see if that register's altered value will be live. */
1446 register rtx r
= SET_DEST (x
);
1447 /* A SET that is a subroutine call cannot be dead. */
1448 if (! call_ok
&& GET_CODE (SET_SRC (x
)) == CALL
)
1452 if (GET_CODE (r
) == CC0
)
1456 if (GET_CODE (r
) == MEM
&& last_mem_set
&& ! MEM_VOLATILE_P (r
)
1457 && rtx_equal_p (r
, last_mem_set
))
1460 while (GET_CODE (r
) == SUBREG
1461 || GET_CODE (r
) == STRICT_LOW_PART
1462 || GET_CODE (r
) == ZERO_EXTRACT
1463 || GET_CODE (r
) == SIGN_EXTRACT
)
1466 if (GET_CODE (r
) == REG
)
1468 register int regno
= REGNO (r
);
1469 register int offset
= regno
/ REGSET_ELT_BITS
;
1470 register int bit
= 1 << (regno
% REGSET_ELT_BITS
);
1472 if ((regno
< FIRST_PSEUDO_REGISTER
&& global_regs
[regno
])
1473 /* Make sure insns to set frame pointer aren't deleted. */
1474 || regno
== FRAME_POINTER_REGNUM
1475 /* Make sure insns to set arg pointer are never deleted. */
1476 || regno
== ARG_POINTER_REGNUM
1477 || (needed
[offset
] & bit
) != 0)
1480 /* If this is a hard register, verify that subsequent words are
1482 if (regno
< FIRST_PSEUDO_REGISTER
)
1484 int n
= HARD_REGNO_NREGS (regno
, GET_MODE (r
));
1487 if ((needed
[(regno
+ n
) / REGSET_ELT_BITS
]
1488 & 1 << ((regno
+ n
) % REGSET_ELT_BITS
)) != 0)
1495 /* If performing several activities,
1496 insn is dead if each activity is individually dead.
1497 Also, CLOBBERs and USEs can be ignored; a CLOBBER or USE
1498 that's inside a PARALLEL doesn't make the insn worth keeping. */
1499 else if (code
== PARALLEL
)
1501 register int i
= XVECLEN (x
, 0);
1502 for (i
--; i
>= 0; i
--)
1504 rtx elt
= XVECEXP (x
, 0, i
);
1505 if (!insn_dead_p (elt
, needed
, call_ok
)
1506 && GET_CODE (elt
) != CLOBBER
1507 && GET_CODE (elt
) != USE
)
1512 /* We do not check CLOBBER or USE here.
1513 An insn consisting of just a CLOBBER or just a USE
1514 should not be deleted. */
1518 /* If X is the pattern of the last insn in a libcall, and assuming X is dead,
1519 return 1 if the entire library call is dead.
1520 This is true if X copies a register (hard or pseudo)
1521 and if the hard return reg of the call insn is dead.
1522 (The caller should have tested the destination of X already for death.)
1524 If this insn doesn't just copy a register, then we don't
1525 have an ordinary libcall. In that case, cse could not have
1526 managed to substitute the source for the dest later on,
1527 so we can assume the libcall is dead.
1529 NEEDED is the bit vector of pseudoregs live before this insn.
1530 NOTE is the REG_RETVAL note of the insn. INSN is the insn itself. */
1533 libcall_dead_p (x
, needed
, note
, insn
)
1539 register RTX_CODE code
= GET_CODE (x
);
1543 register rtx r
= SET_SRC (x
);
1544 if (GET_CODE (r
) == REG
)
1546 rtx call
= XEXP (note
, 0);
1549 /* Find the call insn. */
1550 while (call
!= insn
&& GET_CODE (call
) != CALL_INSN
)
1551 call
= NEXT_INSN (call
);
1553 /* If there is none, do nothing special,
1554 since ordinary death handling can understand these insns. */
1558 /* See if the hard reg holding the value is dead.
1559 If this is a PARALLEL, find the call within it. */
1560 call
= PATTERN (call
);
1561 if (GET_CODE (call
) == PARALLEL
)
1563 for (i
= XVECLEN (call
, 0) - 1; i
>= 0; i
--)
1564 if (GET_CODE (XVECEXP (call
, 0, i
)) == SET
1565 && GET_CODE (SET_SRC (XVECEXP (call
, 0, i
))) == CALL
)
1571 call
= XVECEXP (call
, 0, i
);
1574 return insn_dead_p (call
, needed
, 1);
1580 /* Return 1 if register REGNO was used before it was set.
1581 In other words, if it is live at function entry. */
1584 regno_uninitialized (regno
)
1587 if (n_basic_blocks
== 0)
1590 return (basic_block_live_at_start
[0][regno
/ REGSET_ELT_BITS
]
1591 & (1 << (regno
% REGSET_ELT_BITS
)));
1594 /* 1 if register REGNO was alive at a place where `setjmp' was called
1595 and was set more than once or is an argument.
1596 Such regs may be clobbered by `longjmp'. */
1599 regno_clobbered_at_setjmp (regno
)
1602 if (n_basic_blocks
== 0)
1605 return ((reg_n_sets
[regno
] > 1
1606 || (basic_block_live_at_start
[0][regno
/ REGSET_ELT_BITS
]
1607 & (1 << (regno
% REGSET_ELT_BITS
))))
1608 && (regs_live_at_setjmp
[regno
/ REGSET_ELT_BITS
]
1609 & (1 << (regno
% REGSET_ELT_BITS
))));
1612 /* Process the registers that are set within X.
1613 Their bits are set to 1 in the regset DEAD,
1614 because they are dead prior to this insn.
1616 If INSN is nonzero, it is the insn being processed
1617 and the fact that it is nonzero implies this is the FINAL pass
1618 in propagate_block. In this case, various info about register
1619 usage is stored, LOG_LINKS fields of insns are set up. */
1621 static void mark_set_1 ();
1624 mark_set_regs (needed
, dead
, x
, insn
, significant
)
1631 register RTX_CODE code
= GET_CODE (x
);
1633 if (code
== SET
|| code
== CLOBBER
)
1634 mark_set_1 (needed
, dead
, x
, insn
, significant
);
1635 else if (code
== PARALLEL
)
1638 for (i
= XVECLEN (x
, 0) - 1; i
>= 0; i
--)
1640 code
= GET_CODE (XVECEXP (x
, 0, i
));
1641 if (code
== SET
|| code
== CLOBBER
)
1642 mark_set_1 (needed
, dead
, XVECEXP (x
, 0, i
), insn
, significant
);
1647 /* Process a single SET rtx, X. */
1650 mark_set_1 (needed
, dead
, x
, insn
, significant
)
1658 register rtx reg
= SET_DEST (x
);
1660 /* Modifying just one hardware register of a multi-reg value
1661 or just a byte field of a register
1662 does not mean the value from before this insn is now dead.
1663 But it does mean liveness of that register at the end of the block
1666 Within mark_set_1, however, we treat it as if the register is
1667 indeed modified. mark_used_regs will, however, also treat this
1668 register as being used. Thus, we treat these insns as setting a
1669 new value for the register as a function of its old value. This
1670 cases LOG_LINKS to be made appropriately and this will help combine. */
1672 while (GET_CODE (reg
) == SUBREG
|| GET_CODE (reg
) == ZERO_EXTRACT
1673 || GET_CODE (reg
) == SIGN_EXTRACT
1674 || GET_CODE (reg
) == STRICT_LOW_PART
)
1675 reg
= XEXP (reg
, 0);
1677 /* If we are writing into memory or into a register mentioned in the
1678 address of the last thing stored into memory, show we don't know
1679 what the last store was. If we are writing memory, save the address
1680 unless it is volatile. */
1681 if (GET_CODE (reg
) == MEM
1682 || (GET_CODE (reg
) == REG
1683 && last_mem_set
!= 0 && reg_overlap_mentioned_p (reg
, last_mem_set
)))
1686 if (GET_CODE (reg
) == MEM
&& ! side_effects_p (reg
)
1687 /* There are no REG_INC notes for SP, so we can't assume we'll see
1688 everything that invalidates it. To be safe, don't eliminate any
1689 stores though SP; none of them should be redundant anyway. */
1690 && ! reg_mentioned_p (stack_pointer_rtx
, reg
))
1693 if (GET_CODE (reg
) == REG
1694 && (regno
= REGNO (reg
), regno
!= FRAME_POINTER_REGNUM
)
1695 && regno
!= ARG_POINTER_REGNUM
1696 && ! (regno
< FIRST_PSEUDO_REGISTER
&& global_regs
[regno
]))
1697 /* && regno != STACK_POINTER_REGNUM) -- let's try without this. */
1699 register int offset
= regno
/ REGSET_ELT_BITS
;
1700 register int bit
= 1 << (regno
% REGSET_ELT_BITS
);
1701 int all_needed
= (needed
[offset
] & bit
) != 0;
1702 int some_needed
= (needed
[offset
] & bit
) != 0;
1704 /* Mark it as a significant register for this basic block. */
1706 significant
[offset
] |= bit
;
1708 /* Mark it as as dead before this insn. */
1709 dead
[offset
] |= bit
;
1711 /* A hard reg in a wide mode may really be multiple registers.
1712 If so, mark all of them just like the first. */
1713 if (regno
< FIRST_PSEUDO_REGISTER
)
1717 /* Nothing below is needed for the stack pointer; get out asap.
1718 Eg, log links aren't needed, since combine won't use them. */
1719 if (regno
== STACK_POINTER_REGNUM
)
1722 n
= HARD_REGNO_NREGS (regno
, GET_MODE (reg
));
1726 significant
[(regno
+ n
) / REGSET_ELT_BITS
]
1727 |= 1 << ((regno
+ n
) % REGSET_ELT_BITS
);
1728 dead
[(regno
+ n
) / REGSET_ELT_BITS
]
1729 |= 1 << ((regno
+ n
) % REGSET_ELT_BITS
);
1730 some_needed
|= (needed
[(regno
+ n
) / REGSET_ELT_BITS
]
1731 & 1 << ((regno
+ n
) % REGSET_ELT_BITS
));
1732 all_needed
&= (needed
[(regno
+ n
) / REGSET_ELT_BITS
]
1733 & 1 << ((regno
+ n
) % REGSET_ELT_BITS
));
1736 /* Additional data to record if this is the final pass. */
1739 register rtx y
= reg_next_use
[regno
];
1740 register int blocknum
= BLOCK_NUM (insn
);
1742 /* If this is a hard reg, record this function uses the reg. */
1744 if (regno
< FIRST_PSEUDO_REGISTER
)
1747 int endregno
= regno
+ HARD_REGNO_NREGS (regno
, GET_MODE (reg
));
1749 for (i
= regno
; i
< endregno
; i
++)
1751 regs_ever_live
[i
] = 1;
1757 /* Keep track of which basic blocks each reg appears in. */
1759 if (reg_basic_block
[regno
] == REG_BLOCK_UNKNOWN
)
1760 reg_basic_block
[regno
] = blocknum
;
1761 else if (reg_basic_block
[regno
] != blocknum
)
1762 reg_basic_block
[regno
] = REG_BLOCK_GLOBAL
;
1764 /* Count (weighted) references, stores, etc. This counts a
1765 register twice if it is modified, but that is correct. */
1766 reg_n_sets
[regno
]++;
1768 reg_n_refs
[regno
] += loop_depth
;
1770 /* The insns where a reg is live are normally counted
1771 elsewhere, but we want the count to include the insn
1772 where the reg is set, and the normal counting mechanism
1773 would not count it. */
1774 reg_live_length
[regno
]++;
1777 /* The next use is no longer "next", since a store intervenes. */
1778 reg_next_use
[regno
] = 0;
1782 /* Make a logical link from the next following insn
1783 that uses this register, back to this insn.
1784 The following insns have already been processed.
1786 We don't build a LOG_LINK for hard registers containing
1787 in ASM_OPERANDs. If these registers get replaced,
1788 we might wind up changing the semantics of the insn,
1789 even if reload can make what appear to be valid assignments
1791 if (y
&& (BLOCK_NUM (y
) == blocknum
)
1792 && (regno
>= FIRST_PSEUDO_REGISTER
1793 || asm_noperands (PATTERN (y
)) < 0))
1795 = gen_rtx (INSN_LIST
, VOIDmode
, insn
, LOG_LINKS (y
));
1797 else if (! some_needed
)
1799 /* Note that dead stores have already been deleted when possible
1800 If we get here, we have found a dead store that cannot
1801 be eliminated (because the same insn does something useful).
1802 Indicate this by marking the reg being set as dying here. */
1804 = gen_rtx (EXPR_LIST
, REG_UNUSED
, reg
, REG_NOTES (insn
));
1805 reg_n_deaths
[REGNO (reg
)]++;
1809 /* This is a case where we have a multi-word hard register
1810 and some, but not all, of the words of the register are
1811 needed in subsequent insns. Write REG_UNUSED notes
1812 for those parts that were not needed. This case should
1817 for (i
= HARD_REGNO_NREGS (regno
, GET_MODE (reg
)) - 1;
1819 if ((needed
[(regno
+ i
) / REGSET_ELT_BITS
]
1820 & 1 << ((regno
+ i
) % REGSET_ELT_BITS
)) == 0)
1822 = gen_rtx (EXPR_LIST
, REG_UNUSED
,
1823 gen_rtx (REG
, word_mode
, regno
+ i
),
1829 /* If this is the last pass and this is a SCRATCH, show it will be dying
1830 here and count it. */
1831 else if (GET_CODE (reg
) == SCRATCH
&& insn
!= 0)
1834 = gen_rtx (EXPR_LIST
, REG_UNUSED
, reg
, REG_NOTES (insn
));
1841 /* X is a MEM found in INSN. See if we can convert it into an auto-increment
1845 find_auto_inc (needed
, x
, insn
)
1850 rtx addr
= XEXP (x
, 0);
1853 /* Here we detect use of an index register which might be good for
1854 postincrement, postdecrement, preincrement, or predecrement. */
1856 if (GET_CODE (addr
) == PLUS
&& GET_CODE (XEXP (addr
, 1)) == CONST_INT
)
1857 offset
= INTVAL (XEXP (addr
, 1)), addr
= XEXP (addr
, 0);
1859 if (GET_CODE (addr
) == REG
)
1862 register int size
= GET_MODE_SIZE (GET_MODE (x
));
1865 int regno
= REGNO (addr
);
1867 /* Is the next use an increment that might make auto-increment? */
1868 incr
= reg_next_use
[regno
];
1869 if (incr
&& GET_CODE (PATTERN (incr
)) == SET
1870 && BLOCK_NUM (incr
) == BLOCK_NUM (insn
)
1871 /* Can't add side effects to jumps; if reg is spilled and
1872 reloaded, there's no way to store back the altered value. */
1873 && GET_CODE (insn
) != JUMP_INSN
1874 && (y
= SET_SRC (PATTERN (incr
)), GET_CODE (y
) == PLUS
)
1875 && XEXP (y
, 0) == addr
1876 && GET_CODE (XEXP (y
, 1)) == CONST_INT
1878 #ifdef HAVE_POST_INCREMENT
1879 || (INTVAL (XEXP (y
, 1)) == size
&& offset
== 0)
1881 #ifdef HAVE_POST_DECREMENT
1882 || (INTVAL (XEXP (y
, 1)) == - size
&& offset
== 0)
1884 #ifdef HAVE_PRE_INCREMENT
1885 || (INTVAL (XEXP (y
, 1)) == size
&& offset
== size
)
1887 #ifdef HAVE_PRE_DECREMENT
1888 || (INTVAL (XEXP (y
, 1)) == - size
&& offset
== - size
)
1891 /* Make sure this reg appears only once in this insn. */
1892 && (use
= find_use_as_address (PATTERN (insn
), addr
, offset
),
1893 use
!= 0 && use
!= (rtx
) 1))
1896 rtx q
= SET_DEST (PATTERN (incr
));
1898 if (dead_or_set_p (incr
, addr
))
1900 else if (GET_CODE (q
) == REG
&& ! reg_used_between_p (q
, insn
, incr
))
1902 /* We have *p followed by q = p+size.
1903 Both p and q must be live afterward,
1904 and q must be dead before.
1905 Change it to q = p, ...*q..., q = q+size.
1906 Then fall into the usual case. */
1910 emit_move_insn (q
, addr
);
1911 insns
= get_insns ();
1914 /* If anything in INSNS have UID's that don't fit within the
1915 extra space we allocate earlier, we can't make this auto-inc.
1916 This should never happen. */
1917 for (temp
= insns
; temp
; temp
= NEXT_INSN (temp
))
1919 if (INSN_UID (temp
) > max_uid_for_flow
)
1921 BLOCK_NUM (temp
) = BLOCK_NUM (insn
);
1924 emit_insns_before (insns
, insn
);
1928 /* INCR will become a NOTE and INSN won't contain a
1929 use of ADDR. If a use of ADDR was just placed in
1930 the insn before INSN, make that the next use.
1931 Otherwise, invalidate it. */
1932 if (GET_CODE (PREV_INSN (insn
)) == INSN
1933 && GET_CODE (PATTERN (PREV_INSN (insn
))) == SET
1934 && SET_SRC (PATTERN (PREV_INSN (insn
))) == addr
)
1935 reg_next_use
[regno
] = PREV_INSN (insn
);
1937 reg_next_use
[regno
] = 0;
1943 /* REGNO is now used in INCR which is below INSN, but
1944 it previously wasn't live here. If we don't mark
1945 it as needed, we'll put a REG_DEAD note for it
1946 on this insn, which is incorrect. */
1947 needed
[regno
/ REGSET_ELT_BITS
]
1948 |= 1 << (regno
% REGSET_ELT_BITS
);
1950 /* If there are any calls between INSN and INCR, show
1951 that REGNO now crosses them. */
1952 for (temp
= insn
; temp
!= incr
; temp
= NEXT_INSN (temp
))
1953 if (GET_CODE (temp
) == CALL_INSN
)
1954 reg_n_calls_crossed
[regno
]++;
1959 /* We have found a suitable auto-increment: do POST_INC around
1960 the register here, and patch out the increment instruction
1962 XEXP (x
, 0) = gen_rtx ((INTVAL (XEXP (y
, 1)) == size
1963 ? (offset
? PRE_INC
: POST_INC
)
1964 : (offset
? PRE_DEC
: POST_DEC
)),
1967 /* Record that this insn has an implicit side effect. */
1969 = gen_rtx (EXPR_LIST
, REG_INC
, addr
, REG_NOTES (insn
));
1971 /* Modify the old increment-insn to simply copy
1972 the already-incremented value of our register. */
1973 SET_SRC (PATTERN (incr
)) = addr
;
1974 /* Indicate insn must be re-recognized. */
1975 INSN_CODE (incr
) = -1;
1977 /* If that makes it a no-op (copying the register into itself)
1978 then delete it so it won't appear to be a "use" and a "set"
1979 of this register. */
1980 if (SET_DEST (PATTERN (incr
)) == addr
)
1982 PUT_CODE (incr
, NOTE
);
1983 NOTE_LINE_NUMBER (incr
) = NOTE_INSN_DELETED
;
1984 NOTE_SOURCE_FILE (incr
) = 0;
1987 if (regno
>= FIRST_PSEUDO_REGISTER
)
1989 /* Count an extra reference to the reg. When a reg is
1990 incremented, spilling it is worse, so we want to make
1991 that less likely. */
1992 reg_n_refs
[regno
] += loop_depth
;
1993 /* Count the increment as a setting of the register,
1994 even though it isn't a SET in rtl. */
1995 reg_n_sets
[regno
]++;
2001 #endif /* AUTO_INC_DEC */
2003 /* Scan expression X and store a 1-bit in LIVE for each reg it uses.
2004 This is done assuming the registers needed from X
2005 are those that have 1-bits in NEEDED.
2007 On the final pass, FINAL is 1. This means try for autoincrement
2008 and count the uses and deaths of each pseudo-reg.
2010 INSN is the containing instruction. If INSN is dead, this function is not
2014 mark_used_regs (needed
, live
, x
, final
, insn
)
2021 register RTX_CODE code
;
2026 code
= GET_CODE (x
);
2048 /* Invalidate the data for the last MEM stored. We could do this only
2049 if the addresses conflict, but this doesn't seem worthwhile. */
2054 find_auto_inc (needed
, x
, insn
);
2059 /* See a register other than being set
2060 => mark it as needed. */
2064 register int offset
= regno
/ REGSET_ELT_BITS
;
2065 register int bit
= 1 << (regno
% REGSET_ELT_BITS
);
2066 int all_needed
= (needed
[offset
] & bit
) != 0;
2067 int some_needed
= (needed
[offset
] & bit
) != 0;
2069 live
[offset
] |= bit
;
2070 /* A hard reg in a wide mode may really be multiple registers.
2071 If so, mark all of them just like the first. */
2072 if (regno
< FIRST_PSEUDO_REGISTER
)
2076 /* For stack ptr or arg pointer,
2077 nothing below can be necessary, so waste no more time. */
2078 if (regno
== STACK_POINTER_REGNUM
2079 || regno
== ARG_POINTER_REGNUM
2080 || regno
== FRAME_POINTER_REGNUM
)
2082 /* If this is a register we are going to try to eliminate,
2083 don't mark it live here. If we are successful in
2084 eliminating it, it need not be live unless it is used for
2085 pseudos, in which case it will have been set live when
2086 it was allocated to the pseudos. If the register will not
2087 be eliminated, reload will set it live at that point. */
2089 if (! TEST_HARD_REG_BIT (elim_reg_set
, regno
))
2090 regs_ever_live
[regno
] = 1;
2093 /* No death notes for global register variables;
2094 their values are live after this function exits. */
2095 if (global_regs
[regno
])
2098 n
= HARD_REGNO_NREGS (regno
, GET_MODE (x
));
2101 live
[(regno
+ n
) / REGSET_ELT_BITS
]
2102 |= 1 << ((regno
+ n
) % REGSET_ELT_BITS
);
2103 some_needed
|= (needed
[(regno
+ n
) / REGSET_ELT_BITS
]
2104 & 1 << ((regno
+ n
) % REGSET_ELT_BITS
));
2105 all_needed
&= (needed
[(regno
+ n
) / REGSET_ELT_BITS
]
2106 & 1 << ((regno
+ n
) % REGSET_ELT_BITS
));
2111 /* Record where each reg is used, so when the reg
2112 is set we know the next insn that uses it. */
2114 reg_next_use
[regno
] = insn
;
2116 if (regno
< FIRST_PSEUDO_REGISTER
)
2118 /* If a hard reg is being used,
2119 record that this function does use it. */
2121 i
= HARD_REGNO_NREGS (regno
, GET_MODE (x
));
2125 regs_ever_live
[regno
+ --i
] = 1;
2130 /* Keep track of which basic block each reg appears in. */
2132 register int blocknum
= BLOCK_NUM (insn
);
2134 if (reg_basic_block
[regno
] == REG_BLOCK_UNKNOWN
)
2135 reg_basic_block
[regno
] = blocknum
;
2136 else if (reg_basic_block
[regno
] != blocknum
)
2137 reg_basic_block
[regno
] = REG_BLOCK_GLOBAL
;
2139 /* Count (weighted) number of uses of each reg. */
2141 reg_n_refs
[regno
] += loop_depth
;
2144 /* Record and count the insns in which a reg dies.
2145 If it is used in this insn and was dead below the insn
2146 then it dies in this insn. If it was set in this insn,
2147 we do not make a REG_DEAD note; likewise if we already
2148 made such a note. */
2151 && ! dead_or_set_p (insn
, x
)
2153 && (regno
>= FIRST_PSEUDO_REGISTER
|| ! fixed_regs
[regno
])
2157 /* If none of the words in X is needed, make a REG_DEAD
2158 note. Otherwise, we must make partial REG_DEAD notes. */
2162 = gen_rtx (EXPR_LIST
, REG_DEAD
, x
, REG_NOTES (insn
));
2163 reg_n_deaths
[regno
]++;
2169 /* Don't make a REG_DEAD note for a part of a register
2170 that is set in the insn. */
2172 for (i
= HARD_REGNO_NREGS (regno
, GET_MODE (x
)) - 1;
2174 if ((needed
[(regno
+ i
) / REGSET_ELT_BITS
]
2175 & 1 << ((regno
+ i
) % REGSET_ELT_BITS
)) == 0
2176 && ! dead_or_set_regno_p (insn
, regno
+ i
))
2178 = gen_rtx (EXPR_LIST
, REG_DEAD
,
2179 gen_rtx (REG
, word_mode
, regno
+ i
),
2189 register rtx testreg
= SET_DEST (x
);
2192 /* If storing into MEM, don't show it as being used. But do
2193 show the address as being used. */
2194 if (GET_CODE (testreg
) == MEM
)
2198 find_auto_inc (needed
, testreg
, insn
);
2200 mark_used_regs (needed
, live
, XEXP (testreg
, 0), final
, insn
);
2201 mark_used_regs (needed
, live
, SET_SRC (x
), final
, insn
);
2205 /* Storing in STRICT_LOW_PART is like storing in a reg
2206 in that this SET might be dead, so ignore it in TESTREG.
2207 but in some other ways it is like using the reg.
2209 Storing in a SUBREG or a bit field is like storing the entire
2210 register in that if the register's value is not used
2211 then this SET is not needed. */
2212 while (GET_CODE (testreg
) == STRICT_LOW_PART
2213 || GET_CODE (testreg
) == ZERO_EXTRACT
2214 || GET_CODE (testreg
) == SIGN_EXTRACT
2215 || GET_CODE (testreg
) == SUBREG
)
2217 /* Modifying a single register in an alternate mode
2218 does not use any of the old value. But these other
2219 ways of storing in a register do use the old value. */
2220 if (GET_CODE (testreg
) == SUBREG
2221 && !(REG_SIZE (SUBREG_REG (testreg
)) > REG_SIZE (testreg
)))
2226 testreg
= XEXP (testreg
, 0);
2229 /* If this is a store into a register,
2230 recursively scan the value being stored. */
2232 if (GET_CODE (testreg
) == REG
2233 && (regno
= REGNO (testreg
), regno
!= FRAME_POINTER_REGNUM
)
2234 && regno
!= ARG_POINTER_REGNUM
2235 && ! (regno
< FIRST_PSEUDO_REGISTER
&& global_regs
[regno
]))
2237 mark_used_regs (needed
, live
, SET_SRC (x
), final
, insn
);
2239 mark_used_regs (needed
, live
, SET_DEST (x
), final
, insn
);
2246 /* If exiting needs the right stack value, consider this insn as
2247 using the stack pointer. In any event, consider it as using
2248 all global registers. */
2250 #ifdef EXIT_IGNORE_STACK
2251 if (! EXIT_IGNORE_STACK
2252 || (! FRAME_POINTER_REQUIRED
&& flag_omit_frame_pointer
))
2254 live
[STACK_POINTER_REGNUM
/ REGSET_ELT_BITS
]
2255 |= 1 << (STACK_POINTER_REGNUM
% REGSET_ELT_BITS
);
2257 for (i
= 0; i
< FIRST_PSEUDO_REGISTER
; i
++)
2259 live
[i
/ REGSET_ELT_BITS
] |= 1 << (i
% REGSET_ELT_BITS
);
2263 /* Recursively scan the operands of this expression. */
2266 register char *fmt
= GET_RTX_FORMAT (code
);
2269 for (i
= GET_RTX_LENGTH (code
) - 1; i
>= 0; i
--)
2273 /* Tail recursive case: save a function call level. */
2279 mark_used_regs (needed
, live
, XEXP (x
, i
), final
, insn
);
2281 else if (fmt
[i
] == 'E')
2284 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
2285 mark_used_regs (needed
, live
, XVECEXP (x
, i
, j
), final
, insn
);
2294 try_pre_increment_1 (insn
)
2297 /* Find the next use of this reg. If in same basic block,
2298 make it do pre-increment or pre-decrement if appropriate. */
2299 rtx x
= PATTERN (insn
);
2300 int amount
= ((GET_CODE (SET_SRC (x
)) == PLUS
? 1 : -1)
2301 * INTVAL (XEXP (SET_SRC (x
), 1)));
2302 int regno
= REGNO (SET_DEST (x
));
2303 rtx y
= reg_next_use
[regno
];
2305 && BLOCK_NUM (y
) == BLOCK_NUM (insn
)
2306 && try_pre_increment (y
, SET_DEST (PATTERN (insn
)),
2309 /* We have found a suitable auto-increment
2310 and already changed insn Y to do it.
2311 So flush this increment-instruction. */
2312 PUT_CODE (insn
, NOTE
);
2313 NOTE_LINE_NUMBER (insn
) = NOTE_INSN_DELETED
;
2314 NOTE_SOURCE_FILE (insn
) = 0;
2315 /* Count a reference to this reg for the increment
2316 insn we are deleting. When a reg is incremented.
2317 spilling it is worse, so we want to make that
2319 if (regno
>= FIRST_PSEUDO_REGISTER
)
2321 reg_n_refs
[regno
] += loop_depth
;
2322 reg_n_sets
[regno
]++;
2329 /* Try to change INSN so that it does pre-increment or pre-decrement
2330 addressing on register REG in order to add AMOUNT to REG.
2331 AMOUNT is negative for pre-decrement.
2332 Returns 1 if the change could be made.
2333 This checks all about the validity of the result of modifying INSN. */
2336 try_pre_increment (insn
, reg
, amount
)
2342 /* Nonzero if we can try to make a pre-increment or pre-decrement.
2343 For example, addl $4,r1; movl (r1),... can become movl +(r1),... */
2345 /* Nonzero if we can try to make a post-increment or post-decrement.
2346 For example, addl $4,r1; movl -4(r1),... can become movl (r1)+,...
2347 It is possible for both PRE_OK and POST_OK to be nonzero if the machine
2348 supports both pre-inc and post-inc, or both pre-dec and post-dec. */
2351 /* Nonzero if the opportunity actually requires post-inc or post-dec. */
2354 /* From the sign of increment, see which possibilities are conceivable
2355 on this target machine. */
2356 #ifdef HAVE_PRE_INCREMENT
2360 #ifdef HAVE_POST_INCREMENT
2365 #ifdef HAVE_PRE_DECREMENT
2369 #ifdef HAVE_POST_DECREMENT
2374 if (! (pre_ok
|| post_ok
))
2377 /* It is not safe to add a side effect to a jump insn
2378 because if the incremented register is spilled and must be reloaded
2379 there would be no way to store the incremented value back in memory. */
2381 if (GET_CODE (insn
) == JUMP_INSN
)
2386 use
= find_use_as_address (PATTERN (insn
), reg
, 0);
2387 if (post_ok
&& (use
== 0 || use
== (rtx
) 1))
2389 use
= find_use_as_address (PATTERN (insn
), reg
, -amount
);
2393 if (use
== 0 || use
== (rtx
) 1)
2396 if (GET_MODE_SIZE (GET_MODE (use
)) != (amount
> 0 ? amount
: - amount
))
2399 XEXP (use
, 0) = gen_rtx (amount
> 0
2400 ? (do_post
? POST_INC
: PRE_INC
)
2401 : (do_post
? POST_DEC
: PRE_DEC
),
2404 /* Record that this insn now has an implicit side effect on X. */
2405 REG_NOTES (insn
) = gen_rtx (EXPR_LIST
, REG_INC
, reg
, REG_NOTES (insn
));
2409 #endif /* AUTO_INC_DEC */
2411 /* Find the place in the rtx X where REG is used as a memory address.
2412 Return the MEM rtx that so uses it.
2413 If PLUSCONST is nonzero, search instead for a memory address equivalent to
2414 (plus REG (const_int PLUSCONST)).
2416 If such an address does not appear, return 0.
2417 If REG appears more than once, or is used other than in such an address,
2421 find_use_as_address (x
, reg
, plusconst
)
2426 enum rtx_code code
= GET_CODE (x
);
2427 char *fmt
= GET_RTX_FORMAT (code
);
2429 register rtx value
= 0;
2432 if (code
== MEM
&& XEXP (x
, 0) == reg
&& plusconst
== 0)
2435 if (code
== MEM
&& GET_CODE (XEXP (x
, 0)) == PLUS
2436 && XEXP (XEXP (x
, 0), 0) == reg
2437 && GET_CODE (XEXP (XEXP (x
, 0), 1)) == CONST_INT
2438 && INTVAL (XEXP (XEXP (x
, 0), 1)) == plusconst
)
2441 if (code
== SIGN_EXTRACT
|| code
== ZERO_EXTRACT
)
2443 /* If REG occurs inside a MEM used in a bit-field reference,
2444 that is unacceptable. */
2445 if (find_use_as_address (XEXP (x
, 0), reg
, 0) != 0)
2452 for (i
= GET_RTX_LENGTH (code
) - 1; i
>= 0; i
--)
2456 tem
= find_use_as_address (XEXP (x
, i
), reg
, plusconst
);
2465 for (j
= XVECLEN (x
, i
) - 1; j
>= 0; j
--)
2467 tem
= find_use_as_address (XVECEXP (x
, i
, j
), reg
, plusconst
);
2479 /* Write information about registers and basic blocks into FILE.
2480 This is part of making a debugging dump. */
2483 dump_flow_info (file
)
2487 static char *reg_class_names
[] = REG_CLASS_NAMES
;
2489 fprintf (file
, "%d registers.\n", max_regno
);
2491 for (i
= FIRST_PSEUDO_REGISTER
; i
< max_regno
; i
++)
2494 enum reg_class
class;
2495 fprintf (file
, "\nRegister %d used %d times across %d insns",
2496 i
, reg_n_refs
[i
], reg_live_length
[i
]);
2497 if (reg_basic_block
[i
] >= 0)
2498 fprintf (file
, " in block %d", reg_basic_block
[i
]);
2499 if (reg_n_deaths
[i
] != 1)
2500 fprintf (file
, "; dies in %d places", reg_n_deaths
[i
]);
2501 if (reg_n_calls_crossed
[i
] == 1)
2502 fprintf (file
, "; crosses 1 call");
2503 else if (reg_n_calls_crossed
[i
])
2504 fprintf (file
, "; crosses %d calls", reg_n_calls_crossed
[i
]);
2505 if (PSEUDO_REGNO_BYTES (i
) != UNITS_PER_WORD
)
2506 fprintf (file
, "; %d bytes", PSEUDO_REGNO_BYTES (i
));
2507 class = reg_preferred_class (i
);
2508 if (class != GENERAL_REGS
)
2510 if (reg_preferred_or_nothing (i
))
2511 fprintf (file
, "; %s or none", reg_class_names
[(int) class]);
2513 fprintf (file
, "; pref %s", reg_class_names
[(int) class]);
2515 if (REGNO_POINTER_FLAG (i
))
2516 fprintf (file
, "; pointer");
2517 fprintf (file
, ".\n");
2519 fprintf (file
, "\n%d basic blocks.\n", n_basic_blocks
);
2520 for (i
= 0; i
< n_basic_blocks
; i
++)
2522 register rtx head
, jump
;
2524 fprintf (file
, "\nBasic block %d: first insn %d, last %d.\n",
2526 INSN_UID (basic_block_head
[i
]),
2527 INSN_UID (basic_block_end
[i
]));
2528 /* The control flow graph's storage is freed
2529 now when flow_analysis returns.
2530 Don't try to print it if it is gone. */
2531 if (basic_block_drops_in
)
2533 fprintf (file
, "Reached from blocks: ");
2534 head
= basic_block_head
[i
];
2535 if (GET_CODE (head
) == CODE_LABEL
)
2536 for (jump
= LABEL_REFS (head
);
2538 jump
= LABEL_NEXTREF (jump
))
2540 register int from_block
= BLOCK_NUM (CONTAINING_INSN (jump
));
2541 fprintf (file
, " %d", from_block
);
2543 if (basic_block_drops_in
[i
])
2544 fprintf (file
, " previous");
2546 fprintf (file
, "\nRegisters live at start:");
2547 for (regno
= 0; regno
< max_regno
; regno
++)
2549 register int offset
= regno
/ REGSET_ELT_BITS
;
2550 register int bit
= 1 << (regno
% REGSET_ELT_BITS
);
2551 if (basic_block_live_at_start
[i
][offset
] & bit
)
2552 fprintf (file
, " %d", regno
);
2554 fprintf (file
, "\n");
2556 fprintf (file
, "\n");