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
)
312 rtx nonlocal_label_list
= nonlocal_label_rtx_list ();
314 #ifdef ELIMINABLE_REGS
315 static struct {int from
, to
; } eliminables
[] = ELIMINABLE_REGS
;
318 /* Record which registers will be eliminated. We use this in
321 CLEAR_HARD_REG_SET (elim_reg_set
);
323 #ifdef ELIMINABLE_REGS
324 for (i
= 0; i
< sizeof eliminables
/ sizeof eliminables
[0]; i
++)
325 SET_HARD_REG_BIT (elim_reg_set
, eliminables
[i
].from
);
327 SET_HARD_REG_BIT (elim_reg_set
, FRAME_POINTER_REGNUM
);
330 /* Count the basic blocks. Also find maximum insn uid value used. */
333 register RTX_CODE prev_code
= JUMP_INSN
;
334 register RTX_CODE code
;
336 max_uid_for_flow
= 0;
338 for (insn
= f
, i
= 0; insn
; insn
= NEXT_INSN (insn
))
340 code
= GET_CODE (insn
);
341 if (INSN_UID (insn
) > max_uid_for_flow
)
342 max_uid_for_flow
= INSN_UID (insn
);
343 if (code
== CODE_LABEL
344 || (GET_RTX_CLASS (code
) == 'i'
345 && (prev_code
== JUMP_INSN
346 || (prev_code
== CALL_INSN
347 && nonlocal_label_list
!= 0)
348 || prev_code
== BARRIER
)))
356 /* Leave space for insns we make in some cases for auto-inc. These cases
357 are rare, so we don't need too much space. */
358 max_uid_for_flow
+= max_uid_for_flow
/ 10;
361 /* Allocate some tables that last till end of compiling this function
362 and some needed only in find_basic_blocks and life_analysis. */
365 basic_block_head
= (rtx
*) oballoc (n_basic_blocks
* sizeof (rtx
));
366 basic_block_end
= (rtx
*) oballoc (n_basic_blocks
* sizeof (rtx
));
367 basic_block_drops_in
= (char *) alloca (n_basic_blocks
);
368 basic_block_loop_depth
= (short *) alloca (n_basic_blocks
* sizeof (short));
370 = (short *) alloca ((max_uid_for_flow
+ 1) * sizeof (short));
371 uid_volatile
= (char *) alloca (max_uid_for_flow
+ 1);
372 bzero (uid_volatile
, max_uid_for_flow
+ 1);
374 find_basic_blocks (f
, nonlocal_label_list
);
375 life_analysis (f
, nregs
);
377 dump_flow_info (file
);
379 basic_block_drops_in
= 0;
380 uid_block_number
= 0;
381 basic_block_loop_depth
= 0;
384 /* Find all basic blocks of the function whose first insn is F.
385 Store the correct data in the tables that describe the basic blocks,
386 set up the chains of references for each CODE_LABEL, and
387 delete any entire basic blocks that cannot be reached.
389 NONLOCAL_LABEL_LIST is the same local variable from flow_analysis. */
392 find_basic_blocks (f
, nonlocal_label_list
)
393 rtx f
, nonlocal_label_list
;
397 register char *block_live
= (char *) alloca (n_basic_blocks
);
398 register char *block_marked
= (char *) alloca (n_basic_blocks
);
399 /* List of label_refs to all labels whose addresses are taken
401 rtx label_value_list
= 0;
403 block_live_static
= block_live
;
404 bzero (block_live
, n_basic_blocks
);
405 bzero (block_marked
, n_basic_blocks
);
407 /* Initialize with just block 0 reachable and no blocks marked. */
408 if (n_basic_blocks
> 0)
411 /* Initialize the ref chain of each label to 0. */
412 /* Record where all the blocks start and end and their depth in loops. */
413 /* For each insn, record the block it is in. */
414 /* Also mark as reachable any blocks headed by labels that
415 must not be deleted. */
418 register RTX_CODE prev_code
= JUMP_INSN
;
419 register RTX_CODE code
;
422 for (insn
= f
, i
= -1; insn
; insn
= NEXT_INSN (insn
))
424 code
= GET_CODE (insn
);
427 if (NOTE_LINE_NUMBER (insn
) == NOTE_INSN_LOOP_BEG
)
429 else if (NOTE_LINE_NUMBER (insn
) == NOTE_INSN_LOOP_END
)
432 /* A basic block starts at label, or after something that can jump. */
433 else if (code
== CODE_LABEL
434 || (GET_RTX_CLASS (code
) == 'i'
435 && (prev_code
== JUMP_INSN
436 || (prev_code
== CALL_INSN
437 && nonlocal_label_list
!= 0)
438 || prev_code
== BARRIER
)))
440 basic_block_head
[++i
] = insn
;
441 basic_block_end
[i
] = insn
;
442 basic_block_loop_depth
[i
] = depth
;
443 if (code
== CODE_LABEL
)
445 LABEL_REFS (insn
) = insn
;
446 /* Any label that cannot be deleted
447 is considered to start a reachable block. */
448 if (LABEL_PRESERVE_P (insn
))
452 else if (GET_RTX_CLASS (code
) == 'i')
454 basic_block_end
[i
] = insn
;
455 basic_block_loop_depth
[i
] = depth
;
458 /* Make a list of all labels referred to other than by jumps. */
459 if (code
== INSN
|| code
== CALL_INSN
)
461 rtx note
= find_reg_note (insn
, REG_LABEL
, 0);
463 label_value_list
= gen_rtx (EXPR_LIST
, VOIDmode
, XEXP (note
, 0),
467 BLOCK_NUM (insn
) = i
;
469 /* Don't separate a CALL_INSN from following CLOBBER insns. This is
470 a kludge that will go away when each CALL_INSN records its
474 && ! (prev_code
== CALL_INSN
&& code
== INSN
475 && GET_CODE (PATTERN (insn
)) == CLOBBER
))
478 if (i
+ 1 != n_basic_blocks
)
482 /* Don't delete the labels that are referenced by non-jump instructions. */
485 for (x
= label_value_list
; x
; x
= XEXP (x
, 1))
486 block_live
[BLOCK_NUM (XEXP (x
, 0))] = 1;
489 /* Record which basic blocks control can drop in to. */
493 for (i
= 0; i
< n_basic_blocks
; i
++)
495 register rtx insn
= PREV_INSN (basic_block_head
[i
]);
496 /* TEMP1 is used to avoid a bug in Sequent's compiler. */
498 while (insn
&& GET_CODE (insn
) == NOTE
)
499 insn
= PREV_INSN (insn
);
500 temp1
= insn
&& GET_CODE (insn
) != BARRIER
;
501 basic_block_drops_in
[i
] = temp1
;
505 /* Now find which basic blocks can actually be reached
506 and put all jump insns' LABEL_REFS onto the ref-chains
507 of their target labels. */
509 if (n_basic_blocks
> 0)
511 int something_marked
= 1;
513 /* Find all indirect jump insns and mark them as possibly jumping
514 to all the labels whose addresses are explicitly used.
515 This is because, when there are computed gotos,
516 we can't tell which labels they jump to, of all the possibilities. */
518 for (insn
= f
; insn
; insn
= NEXT_INSN (insn
))
519 if (GET_CODE (insn
) == JUMP_INSN
520 && GET_CODE (PATTERN (insn
)) == SET
521 && SET_DEST (PATTERN (insn
)) == pc_rtx
522 && (GET_CODE (SET_SRC (PATTERN (insn
))) == REG
523 || GET_CODE (SET_SRC (PATTERN (insn
))) == MEM
))
526 for (x
= label_value_list
; x
; x
= XEXP (x
, 1))
527 mark_label_ref (gen_rtx (LABEL_REF
, VOIDmode
, XEXP (x
, 0)),
529 for (x
= forced_labels
; x
; x
= XEXP (x
, 1))
530 mark_label_ref (gen_rtx (LABEL_REF
, VOIDmode
, XEXP (x
, 0)),
534 /* Find all call insns and mark them as possibly jumping
535 to all the nonlocal goto handler labels. */
537 for (insn
= f
; insn
; insn
= NEXT_INSN (insn
))
538 if (GET_CODE (insn
) == CALL_INSN
)
541 for (x
= nonlocal_label_list
; x
; x
= XEXP (x
, 1))
542 mark_label_ref (gen_rtx (LABEL_REF
, VOIDmode
, XEXP (x
, 0)),
544 /* ??? This could be made smarter:
545 in some cases it's possible to tell that certain
546 calls will not do a nonlocal goto.
548 For example, if the nested functions that do the
549 nonlocal gotos do not have their addresses taken, then
550 only calls to those functions or to other nested
551 functions that use them could possibly do nonlocal
555 /* Pass over all blocks, marking each block that is reachable
556 and has not yet been marked.
557 Keep doing this until, in one pass, no blocks have been marked.
558 Then blocks_live and blocks_marked are identical and correct.
559 In addition, all jumps actually reachable have been marked. */
561 while (something_marked
)
563 something_marked
= 0;
564 for (i
= 0; i
< n_basic_blocks
; i
++)
565 if (block_live
[i
] && !block_marked
[i
])
568 something_marked
= 1;
569 if (i
+ 1 < n_basic_blocks
&& basic_block_drops_in
[i
+ 1])
570 block_live
[i
+ 1] = 1;
571 insn
= basic_block_end
[i
];
572 if (GET_CODE (insn
) == JUMP_INSN
)
573 mark_label_ref (PATTERN (insn
), insn
, 0);
577 /* Now delete the code for any basic blocks that can't be reached.
578 They can occur because jump_optimize does not recognize
579 unreachable loops as unreachable. */
581 for (i
= 0; i
< n_basic_blocks
; i
++)
584 insn
= basic_block_head
[i
];
587 if (GET_CODE (insn
) == BARRIER
)
589 if (GET_CODE (insn
) != NOTE
)
591 PUT_CODE (insn
, NOTE
);
592 NOTE_LINE_NUMBER (insn
) = NOTE_INSN_DELETED
;
593 NOTE_SOURCE_FILE (insn
) = 0;
595 if (insn
== basic_block_end
[i
])
597 /* BARRIERs are between basic blocks, not part of one.
598 Delete a BARRIER if the preceding jump is deleted.
599 We cannot alter a BARRIER into a NOTE
600 because it is too short; but we can really delete
601 it because it is not part of a basic block. */
602 if (NEXT_INSN (insn
) != 0
603 && GET_CODE (NEXT_INSN (insn
)) == BARRIER
)
604 delete_insn (NEXT_INSN (insn
));
607 insn
= NEXT_INSN (insn
);
609 /* Each time we delete some basic blocks,
610 see if there is a jump around them that is
611 being turned into a no-op. If so, delete it. */
613 if (block_live
[i
- 1])
616 for (j
= i
; j
< n_basic_blocks
; j
++)
620 insn
= basic_block_end
[i
- 1];
621 if (GET_CODE (insn
) == JUMP_INSN
622 /* An unconditional jump is the only possibility
623 we must check for, since a conditional one
624 would make these blocks live. */
625 && simplejump_p (insn
)
626 && (label
= XEXP (SET_SRC (PATTERN (insn
)), 0), 1)
627 && INSN_UID (label
) != 0
628 && BLOCK_NUM (label
) == j
)
630 PUT_CODE (insn
, NOTE
);
631 NOTE_LINE_NUMBER (insn
) = NOTE_INSN_DELETED
;
632 NOTE_SOURCE_FILE (insn
) = 0;
633 if (GET_CODE (NEXT_INSN (insn
)) != BARRIER
)
635 delete_insn (NEXT_INSN (insn
));
644 /* Check expression X for label references;
645 if one is found, add INSN to the label's chain of references.
647 CHECKDUP means check for and avoid creating duplicate references
648 from the same insn. Such duplicates do no serious harm but
649 can slow life analysis. CHECKDUP is set only when duplicates
653 mark_label_ref (x
, insn
, checkdup
)
657 register RTX_CODE code
;
661 /* We can be called with NULL when scanning label_value_list. */
666 if (code
== LABEL_REF
)
668 register rtx label
= XEXP (x
, 0);
670 if (GET_CODE (label
) != CODE_LABEL
)
672 /* If the label was never emitted, this insn is junk,
673 but avoid a crash trying to refer to BLOCK_NUM (label).
674 This can happen as a result of a syntax error
675 and a diagnostic has already been printed. */
676 if (INSN_UID (label
) == 0)
678 CONTAINING_INSN (x
) = insn
;
679 /* if CHECKDUP is set, check for duplicate ref from same insn
682 for (y
= LABEL_REFS (label
); y
!= label
; y
= LABEL_NEXTREF (y
))
683 if (CONTAINING_INSN (y
) == insn
)
685 LABEL_NEXTREF (x
) = LABEL_REFS (label
);
686 LABEL_REFS (label
) = x
;
687 block_live_static
[BLOCK_NUM (label
)] = 1;
691 fmt
= GET_RTX_FORMAT (code
);
692 for (i
= GET_RTX_LENGTH (code
) - 1; i
>= 0; i
--)
695 mark_label_ref (XEXP (x
, i
), insn
, 0);
699 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
700 mark_label_ref (XVECEXP (x
, i
, j
), insn
, 1);
705 /* Determine which registers are live at the start of each
706 basic block of the function whose first insn is F.
707 NREGS is the number of registers used in F.
708 We allocate the vector basic_block_live_at_start
709 and the regsets that it points to, and fill them with the data.
710 regset_size and regset_bytes are also set here. */
713 life_analysis (f
, nregs
)
720 /* For each basic block, a bitmask of regs
721 live on exit from the block. */
722 regset
*basic_block_live_at_end
;
723 /* For each basic block, a bitmask of regs
724 live on entry to a successor-block of this block.
725 If this does not match basic_block_live_at_end,
726 that must be updated, and the block must be rescanned. */
727 regset
*basic_block_new_live_at_end
;
728 /* For each basic block, a bitmask of regs
729 whose liveness at the end of the basic block
730 can make a difference in which regs are live on entry to the block.
731 These are the regs that are set within the basic block,
732 possibly excluding those that are used after they are set. */
733 regset
*basic_block_significant
;
737 struct obstack flow_obstack
;
739 gcc_obstack_init (&flow_obstack
);
743 bzero (regs_ever_live
, sizeof regs_ever_live
);
745 /* Allocate and zero out many data structures
746 that will record the data from lifetime analysis. */
748 allocate_for_life_analysis ();
750 reg_next_use
= (rtx
*) alloca (nregs
* sizeof (rtx
));
751 bzero (reg_next_use
, nregs
* sizeof (rtx
));
753 /* Set up several regset-vectors used internally within this function.
754 Their meanings are documented above, with their declarations. */
756 basic_block_live_at_end
= (regset
*) alloca (n_basic_blocks
* sizeof (regset
));
757 /* Don't use alloca since that leads to a crash rather than an error message
758 if there isn't enough space.
759 Don't use oballoc since we may need to allocate other things during
760 this function on the temporary obstack. */
761 tem
= (regset
) obstack_alloc (&flow_obstack
, n_basic_blocks
* regset_bytes
);
762 bzero (tem
, n_basic_blocks
* regset_bytes
);
763 init_regset_vector (basic_block_live_at_end
, tem
, n_basic_blocks
, regset_bytes
);
765 basic_block_new_live_at_end
= (regset
*) alloca (n_basic_blocks
* sizeof (regset
));
766 tem
= (regset
) obstack_alloc (&flow_obstack
, n_basic_blocks
* regset_bytes
);
767 bzero (tem
, n_basic_blocks
* regset_bytes
);
768 init_regset_vector (basic_block_new_live_at_end
, tem
, n_basic_blocks
, regset_bytes
);
770 basic_block_significant
= (regset
*) alloca (n_basic_blocks
* sizeof (regset
));
771 tem
= (regset
) obstack_alloc (&flow_obstack
, n_basic_blocks
* regset_bytes
);
772 bzero (tem
, n_basic_blocks
* regset_bytes
);
773 init_regset_vector (basic_block_significant
, tem
, n_basic_blocks
, regset_bytes
);
775 /* Record which insns refer to any volatile memory
776 or for any reason can't be deleted just because they are dead stores.
777 Also, delete any insns that copy a register to itself. */
779 for (insn
= f
; insn
; insn
= NEXT_INSN (insn
))
781 enum rtx_code code1
= GET_CODE (insn
);
782 if (code1
== CALL_INSN
)
783 INSN_VOLATILE (insn
) = 1;
784 else if (code1
== INSN
|| code1
== JUMP_INSN
)
786 /* Delete (in effect) any obvious no-op moves. */
787 if (GET_CODE (PATTERN (insn
)) == SET
788 && GET_CODE (SET_DEST (PATTERN (insn
))) == REG
789 && GET_CODE (SET_SRC (PATTERN (insn
))) == REG
790 && REGNO (SET_DEST (PATTERN (insn
))) ==
791 REGNO (SET_SRC (PATTERN (insn
)))
792 /* Insns carrying these notes are useful later on. */
793 && ! find_reg_note (insn
, REG_EQUAL
, 0))
795 PUT_CODE (insn
, NOTE
);
796 NOTE_LINE_NUMBER (insn
) = NOTE_INSN_DELETED
;
797 NOTE_SOURCE_FILE (insn
) = 0;
799 else if (GET_CODE (PATTERN (insn
)) == PARALLEL
)
801 /* If nothing but SETs of registers to themselves,
802 this insn can also be deleted. */
803 for (i
= 0; i
< XVECLEN (PATTERN (insn
), 0); i
++)
805 rtx tem
= XVECEXP (PATTERN (insn
), 0, i
);
807 if (GET_CODE (tem
) == USE
808 || GET_CODE (tem
) == CLOBBER
)
811 if (GET_CODE (tem
) != SET
812 || GET_CODE (SET_DEST (tem
)) != REG
813 || GET_CODE (SET_SRC (tem
)) != REG
814 || REGNO (SET_DEST (tem
)) != REGNO (SET_SRC (tem
)))
818 if (i
== XVECLEN (PATTERN (insn
), 0)
819 /* Insns carrying these notes are useful later on. */
820 && ! find_reg_note (insn
, REG_EQUAL
, 0))
822 PUT_CODE (insn
, NOTE
);
823 NOTE_LINE_NUMBER (insn
) = NOTE_INSN_DELETED
;
824 NOTE_SOURCE_FILE (insn
) = 0;
827 INSN_VOLATILE (insn
) = volatile_refs_p (PATTERN (insn
));
829 else if (GET_CODE (PATTERN (insn
)) != USE
)
830 INSN_VOLATILE (insn
) = volatile_refs_p (PATTERN (insn
));
831 /* A SET that makes space on the stack cannot be dead.
832 (Such SETs occur only for allocating variable-size data,
833 so they will always have a PLUS or MINUS according to the
834 direction of stack growth.)
835 Even if this function never uses this stack pointer value,
836 signal handlers do! */
837 else if (code1
== INSN
&& GET_CODE (PATTERN (insn
)) == SET
838 && SET_DEST (PATTERN (insn
)) == stack_pointer_rtx
839 #ifdef STACK_GROWS_DOWNWARD
840 && GET_CODE (SET_SRC (PATTERN (insn
))) == MINUS
842 && GET_CODE (SET_SRC (PATTERN (insn
))) == PLUS
844 && XEXP (SET_SRC (PATTERN (insn
)), 0) == stack_pointer_rtx
)
845 INSN_VOLATILE (insn
) = 1;
849 if (n_basic_blocks
> 0)
850 #ifdef EXIT_IGNORE_STACK
851 if (! EXIT_IGNORE_STACK
852 || (! FRAME_POINTER_REQUIRED
&& flag_omit_frame_pointer
))
855 /* If exiting needs the right stack value,
856 consider the stack pointer live at the end of the function. */
857 basic_block_live_at_end
[n_basic_blocks
- 1]
858 [STACK_POINTER_REGNUM
/ REGSET_ELT_BITS
]
859 |= 1 << (STACK_POINTER_REGNUM
% REGSET_ELT_BITS
);
860 basic_block_new_live_at_end
[n_basic_blocks
- 1]
861 [STACK_POINTER_REGNUM
/ REGSET_ELT_BITS
]
862 |= 1 << (STACK_POINTER_REGNUM
% REGSET_ELT_BITS
);
865 /* Mark all global registers as being live at the end of the function
866 since they may be referenced by our caller. */
868 if (n_basic_blocks
> 0)
869 for (i
= 0; i
< FIRST_PSEUDO_REGISTER
; i
++)
872 basic_block_live_at_end
[n_basic_blocks
- 1]
873 [i
/ REGSET_ELT_BITS
] |= 1 << (i
% REGSET_ELT_BITS
);
874 basic_block_new_live_at_end
[n_basic_blocks
- 1]
875 [i
/ REGSET_ELT_BITS
] |= 1 << (i
% REGSET_ELT_BITS
);
878 /* Propagate life info through the basic blocks
879 around the graph of basic blocks.
881 This is a relaxation process: each time a new register
882 is live at the end of the basic block, we must scan the block
883 to determine which registers are, as a consequence, live at the beginning
884 of that block. These registers must then be marked live at the ends
885 of all the blocks that can transfer control to that block.
886 The process continues until it reaches a fixed point. */
893 for (i
= n_basic_blocks
- 1; i
>= 0; i
--)
895 int consider
= first_pass
;
896 int must_rescan
= first_pass
;
901 /* Set CONSIDER if this block needs thinking about at all
902 (that is, if the regs live now at the end of it
903 are not the same as were live at the end of it when
904 we last thought about it).
905 Set must_rescan if it needs to be thought about
906 instruction by instruction (that is, if any additional
907 reg that is live at the end now but was not live there before
908 is one of the significant regs of this basic block). */
910 for (j
= 0; j
< regset_size
; j
++)
912 register int x
= (basic_block_new_live_at_end
[i
][j
]
913 & ~basic_block_live_at_end
[i
][j
]);
916 if (x
& basic_block_significant
[i
][j
])
928 /* The live_at_start of this block may be changing,
929 so another pass will be required after this one. */
934 /* No complete rescan needed;
935 just record those variables newly known live at end
936 as live at start as well. */
937 for (j
= 0; j
< regset_size
; j
++)
939 register int x
= basic_block_new_live_at_end
[i
][j
]
940 & ~basic_block_live_at_end
[i
][j
];
941 basic_block_live_at_start
[i
][j
] |= x
;
942 basic_block_live_at_end
[i
][j
] |= x
;
947 /* Update the basic_block_live_at_start
948 by propagation backwards through the block. */
949 bcopy (basic_block_new_live_at_end
[i
],
950 basic_block_live_at_end
[i
], regset_bytes
);
951 bcopy (basic_block_live_at_end
[i
],
952 basic_block_live_at_start
[i
], regset_bytes
);
953 propagate_block (basic_block_live_at_start
[i
],
954 basic_block_head
[i
], basic_block_end
[i
], 0,
955 first_pass
? basic_block_significant
[i
] : 0,
960 register rtx jump
, head
;
961 /* Update the basic_block_new_live_at_end's of the block
962 that falls through into this one (if any). */
963 head
= basic_block_head
[i
];
964 jump
= PREV_INSN (head
);
965 if (basic_block_drops_in
[i
])
967 register int from_block
= BLOCK_NUM (jump
);
969 for (j
= 0; j
< regset_size
; j
++)
970 basic_block_new_live_at_end
[from_block
][j
]
971 |= basic_block_live_at_start
[i
][j
];
973 /* Update the basic_block_new_live_at_end's of
974 all the blocks that jump to this one. */
975 if (GET_CODE (head
) == CODE_LABEL
)
976 for (jump
= LABEL_REFS (head
);
978 jump
= LABEL_NEXTREF (jump
))
980 register int from_block
= BLOCK_NUM (CONTAINING_INSN (jump
));
982 for (j
= 0; j
< regset_size
; j
++)
983 basic_block_new_live_at_end
[from_block
][j
]
984 |= basic_block_live_at_start
[i
][j
];
994 /* The only pseudos that are live at the beginning of the function are
995 those that were not set anywhere in the function. local-alloc doesn't
996 know how to handle these correctly, so mark them as not local to any
999 if (n_basic_blocks
> 0)
1000 for (i
= FIRST_PSEUDO_REGISTER
; i
< max_regno
; i
++)
1001 if (basic_block_live_at_start
[0][i
/ REGSET_ELT_BITS
]
1002 & (1 << (i
% REGSET_ELT_BITS
)))
1003 reg_basic_block
[i
] = REG_BLOCK_GLOBAL
;
1005 /* Now the life information is accurate.
1006 Make one more pass over each basic block
1007 to delete dead stores, create autoincrement addressing
1008 and record how many times each register is used, is set, or dies.
1010 To save time, we operate directly in basic_block_live_at_end[i],
1011 thus destroying it (in fact, converting it into a copy of
1012 basic_block_live_at_start[i]). This is ok now because
1013 basic_block_live_at_end[i] is no longer used past this point. */
1017 for (i
= 0; i
< n_basic_blocks
; i
++)
1019 propagate_block (basic_block_live_at_end
[i
],
1020 basic_block_head
[i
], basic_block_end
[i
], 1, 0, i
);
1027 /* Something live during a setjmp should not be put in a register
1028 on certain machines which restore regs from stack frames
1029 rather than from the jmpbuf.
1030 But we don't need to do this for the user's variables, since
1031 ANSI says only volatile variables need this. */
1032 #ifdef LONGJMP_RESTORE_FROM_STACK
1033 for (i
= FIRST_PSEUDO_REGISTER
; i
< nregs
; i
++)
1034 if (regs_live_at_setjmp
[i
/ REGSET_ELT_BITS
] & (1 << (i
% REGSET_ELT_BITS
))
1035 && regno_reg_rtx
[i
] != 0 && ! REG_USERVAR_P (regno_reg_rtx
[i
]))
1037 reg_live_length
[i
] = -1;
1038 reg_basic_block
[i
] = -1;
1043 /* We have a problem with any pseudoreg that
1044 lives across the setjmp. ANSI says that if a
1045 user variable does not change in value
1046 between the setjmp and the longjmp, then the longjmp preserves it.
1047 This includes longjmp from a place where the pseudo appears dead.
1048 (In principle, the value still exists if it is in scope.)
1049 If the pseudo goes in a hard reg, some other value may occupy
1050 that hard reg where this pseudo is dead, thus clobbering the pseudo.
1051 Conclusion: such a pseudo must not go in a hard reg. */
1052 for (i
= FIRST_PSEUDO_REGISTER
; i
< nregs
; i
++)
1053 if (regs_live_at_setjmp
[i
/ REGSET_ELT_BITS
] & (1 << (i
% REGSET_ELT_BITS
))
1054 && regno_reg_rtx
[i
] != 0)
1056 reg_live_length
[i
] = -1;
1057 reg_basic_block
[i
] = -1;
1060 obstack_free (&flow_obstack
, 0);
1063 /* Subroutines of life analysis. */
1065 /* Allocate the permanent data structures that represent the results
1066 of life analysis. Not static since used also for stupid life analysis. */
1069 allocate_for_life_analysis ()
1072 register regset tem
;
1074 regset_size
= ((max_regno
+ REGSET_ELT_BITS
- 1) / REGSET_ELT_BITS
);
1075 regset_bytes
= regset_size
* sizeof (*(regset
)0);
1077 reg_n_refs
= (int *) oballoc (max_regno
* sizeof (int));
1078 bzero (reg_n_refs
, max_regno
* sizeof (int));
1080 reg_n_sets
= (short *) oballoc (max_regno
* sizeof (short));
1081 bzero (reg_n_sets
, max_regno
* sizeof (short));
1083 reg_n_deaths
= (short *) oballoc (max_regno
* sizeof (short));
1084 bzero (reg_n_deaths
, max_regno
* sizeof (short));
1086 reg_live_length
= (int *) oballoc (max_regno
* sizeof (int));
1087 bzero (reg_live_length
, max_regno
* sizeof (int));
1089 reg_n_calls_crossed
= (int *) oballoc (max_regno
* sizeof (int));
1090 bzero (reg_n_calls_crossed
, max_regno
* sizeof (int));
1092 reg_basic_block
= (short *) oballoc (max_regno
* sizeof (short));
1093 for (i
= 0; i
< max_regno
; i
++)
1094 reg_basic_block
[i
] = REG_BLOCK_UNKNOWN
;
1096 basic_block_live_at_start
= (regset
*) oballoc (n_basic_blocks
* sizeof (regset
));
1097 tem
= (regset
) oballoc (n_basic_blocks
* regset_bytes
);
1098 bzero (tem
, n_basic_blocks
* regset_bytes
);
1099 init_regset_vector (basic_block_live_at_start
, tem
, n_basic_blocks
, regset_bytes
);
1101 regs_live_at_setjmp
= (regset
) oballoc (regset_bytes
);
1102 bzero (regs_live_at_setjmp
, regset_bytes
);
1105 /* Make each element of VECTOR point at a regset,
1106 taking the space for all those regsets from SPACE.
1107 SPACE is of type regset, but it is really as long as NELTS regsets.
1108 BYTES_PER_ELT is the number of bytes in one regset. */
1111 init_regset_vector (vector
, space
, nelts
, bytes_per_elt
)
1118 register regset p
= space
;
1120 for (i
= 0; i
< nelts
; i
++)
1123 p
+= bytes_per_elt
/ sizeof (*p
);
1127 /* Compute the registers live at the beginning of a basic block
1128 from those live at the end.
1130 When called, OLD contains those live at the end.
1131 On return, it contains those live at the beginning.
1132 FIRST and LAST are the first and last insns of the basic block.
1134 FINAL is nonzero if we are doing the final pass which is not
1135 for computing the life info (since that has already been done)
1136 but for acting on it. On this pass, we delete dead stores,
1137 set up the logical links and dead-variables lists of instructions,
1138 and merge instructions for autoincrement and autodecrement addresses.
1140 SIGNIFICANT is nonzero only the first time for each basic block.
1141 If it is nonzero, it points to a regset in which we store
1142 a 1 for each register that is set within the block.
1144 BNUM is the number of the basic block. */
1147 propagate_block (old
, first
, last
, final
, significant
, bnum
)
1148 register regset old
;
1160 /* The following variables are used only if FINAL is nonzero. */
1161 /* This vector gets one element for each reg that has been live
1162 at any point in the basic block that has been scanned so far.
1163 SOMETIMES_MAX says how many elements are in use so far.
1164 In each element, OFFSET is the byte-number within a regset
1165 for the register described by the element, and BIT is a mask
1166 for that register's bit within the byte. */
1167 register struct foo
{ short offset
; short bit
; } *regs_sometimes_live
;
1168 int sometimes_max
= 0;
1169 /* This regset has 1 for each reg that we have seen live so far.
1170 It and REGS_SOMETIMES_LIVE are updated together. */
1173 /* The loop depth may change in the middle of a basic block. Since we
1174 scan from end to beginning, we start with the depth at the end of the
1175 current basic block, and adjust as we pass ends and starts of loops. */
1176 loop_depth
= basic_block_loop_depth
[bnum
];
1178 dead
= (regset
) alloca (regset_bytes
);
1179 live
= (regset
) alloca (regset_bytes
);
1184 /* Include any notes at the end of the block in the scan.
1185 This is in case the block ends with a call to setjmp. */
1187 while (NEXT_INSN (last
) != 0 && GET_CODE (NEXT_INSN (last
)) == NOTE
)
1189 /* Look for loop boundaries, we are going forward here. */
1190 last
= NEXT_INSN (last
);
1191 if (NOTE_LINE_NUMBER (last
) == NOTE_INSN_LOOP_BEG
)
1193 else if (NOTE_LINE_NUMBER (last
) == NOTE_INSN_LOOP_END
)
1199 register int i
, offset
, bit
;
1202 maxlive
= (regset
) alloca (regset_bytes
);
1203 bcopy (old
, maxlive
, regset_bytes
);
1205 = (struct foo
*) alloca (max_regno
* sizeof (struct foo
));
1207 /* Process the regs live at the end of the block.
1208 Enter them in MAXLIVE and REGS_SOMETIMES_LIVE.
1209 Also mark them as not local to any one basic block. */
1211 for (offset
= 0, i
= 0; offset
< regset_size
; offset
++)
1212 for (bit
= 1; bit
; bit
<<= 1, i
++)
1216 if (old
[offset
] & bit
)
1218 reg_basic_block
[i
] = REG_BLOCK_GLOBAL
;
1219 regs_sometimes_live
[sometimes_max
].offset
= offset
;
1220 regs_sometimes_live
[sometimes_max
].bit
= i
% REGSET_ELT_BITS
;
1226 /* Scan the block an insn at a time from end to beginning. */
1228 for (insn
= last
; ; insn
= prev
)
1230 prev
= PREV_INSN (insn
);
1232 /* Look for loop boundaries, remembering that we are going backwards. */
1233 if (GET_CODE (insn
) == NOTE
1234 && NOTE_LINE_NUMBER (insn
) == NOTE_INSN_LOOP_END
)
1236 else if (GET_CODE (insn
) == NOTE
1237 && NOTE_LINE_NUMBER (insn
) == NOTE_INSN_LOOP_BEG
)
1240 /* If we have LOOP_DEPTH == 0, there has been a bookkeeping error.
1241 Abort now rather than setting register status incorrectly. */
1242 if (loop_depth
== 0)
1245 /* If this is a call to `setjmp' et al,
1246 warn if any non-volatile datum is live. */
1248 if (final
&& GET_CODE (insn
) == NOTE
1249 && NOTE_LINE_NUMBER (insn
) == NOTE_INSN_SETJMP
)
1252 for (i
= 0; i
< regset_size
; i
++)
1253 regs_live_at_setjmp
[i
] |= old
[i
];
1256 /* Update the life-status of regs for this insn.
1257 First DEAD gets which regs are set in this insn
1258 then LIVE gets which regs are used in this insn.
1259 Then the regs live before the insn
1260 are those live after, with DEAD regs turned off,
1261 and then LIVE regs turned on. */
1263 if (GET_RTX_CLASS (GET_CODE (insn
)) == 'i')
1266 rtx note
= find_reg_note (insn
, REG_RETVAL
, 0);
1268 = (insn_dead_p (PATTERN (insn
), old
, 0)
1269 /* Don't delete something that refers to volatile storage! */
1270 && ! INSN_VOLATILE (insn
));
1272 = (insn_is_dead
&& note
!= 0
1273 && libcall_dead_p (PATTERN (insn
), old
, note
, insn
));
1275 /* If an instruction consists of just dead store(s) on final pass,
1276 "delete" it by turning it into a NOTE of type NOTE_INSN_DELETED.
1277 We could really delete it with delete_insn, but that
1278 can cause trouble for first or last insn in a basic block. */
1279 if (final
&& insn_is_dead
)
1281 PUT_CODE (insn
, NOTE
);
1282 NOTE_LINE_NUMBER (insn
) = NOTE_INSN_DELETED
;
1283 NOTE_SOURCE_FILE (insn
) = 0;
1285 /* CC0 is now known to be dead. Either this insn used it,
1286 in which case it doesn't anymore, or clobbered it,
1287 so the next insn can't use it. */
1290 /* If this insn is copying the return value from a library call,
1291 delete the entire library call. */
1292 if (libcall_is_dead
)
1294 rtx first
= XEXP (note
, 0);
1296 while (INSN_DELETED_P (first
))
1297 first
= NEXT_INSN (first
);
1302 NOTE_LINE_NUMBER (p
) = NOTE_INSN_DELETED
;
1303 NOTE_SOURCE_FILE (p
) = 0;
1309 for (i
= 0; i
< regset_size
; i
++)
1311 dead
[i
] = 0; /* Faster than bzero here */
1312 live
[i
] = 0; /* since regset_size is usually small */
1315 /* See if this is an increment or decrement that can be
1316 merged into a following memory address. */
1319 register rtx x
= PATTERN (insn
);
1320 /* Does this instruction increment or decrement a register? */
1321 if (final
&& GET_CODE (x
) == SET
1322 && GET_CODE (SET_DEST (x
)) == REG
1323 && (GET_CODE (SET_SRC (x
)) == PLUS
1324 || GET_CODE (SET_SRC (x
)) == MINUS
)
1325 && XEXP (SET_SRC (x
), 0) == SET_DEST (x
)
1326 && GET_CODE (XEXP (SET_SRC (x
), 1)) == CONST_INT
1327 /* Ok, look for a following memory ref we can combine with.
1328 If one is found, change the memory ref to a PRE_INC
1329 or PRE_DEC, cancel this insn, and return 1.
1330 Return 0 if nothing has been done. */
1331 && try_pre_increment_1 (insn
))
1334 #endif /* AUTO_INC_DEC */
1336 /* If this is not the final pass, and this insn is copying the
1337 value of a library call and it's dead, don't scan the
1338 insns that perform the library call, so that the call's
1339 arguments are not marked live. */
1340 if (libcall_is_dead
)
1342 /* Mark the dest reg as `significant'. */
1343 mark_set_regs (old
, dead
, PATTERN (insn
), 0, significant
);
1345 insn
= XEXP (note
, 0);
1346 prev
= PREV_INSN (insn
);
1348 else if (GET_CODE (PATTERN (insn
)) == SET
1349 && SET_DEST (PATTERN (insn
)) == stack_pointer_rtx
1350 && GET_CODE (SET_SRC (PATTERN (insn
))) == PLUS
1351 && XEXP (SET_SRC (PATTERN (insn
)), 0) == stack_pointer_rtx
1352 && GET_CODE (XEXP (SET_SRC (PATTERN (insn
)), 1)) == CONST_INT
)
1353 /* We have an insn to pop a constant amount off the stack.
1354 (Such insns use PLUS regardless of the direction of the stack,
1355 and any insn to adjust the stack by a constant is always a pop.)
1356 These insns, if not dead stores, have no effect on life. */
1360 /* LIVE gets the regs used in INSN;
1361 DEAD gets those set by it. Dead insns don't make anything
1364 mark_set_regs (old
, dead
, PATTERN (insn
), final
? insn
: 0,
1367 /* If an insn doesn't use CC0, it becomes dead since we
1368 assume that every insn clobbers it. So show it dead here;
1369 mark_used_regs will set it live if it is referenced. */
1373 mark_used_regs (old
, live
, PATTERN (insn
), final
, insn
);
1375 /* Sometimes we may have inserted something before INSN (such as
1376 a move) when we make an auto-inc. So ensure we will scan
1379 prev
= PREV_INSN (insn
);
1382 if (! insn_is_dead
&& GET_CODE (insn
) == CALL_INSN
)
1386 /* Each call clobbers all call-clobbered regs that are not
1387 global. Note that the function-value reg is a
1388 call-clobbered reg, and mark_set_regs has already had
1389 a chance to handle it. */
1391 for (i
= 0; i
< FIRST_PSEUDO_REGISTER
; i
++)
1392 if (call_used_regs
[i
] && ! global_regs
[i
])
1393 dead
[i
/ REGSET_ELT_BITS
]
1394 |= (1 << (i
% REGSET_ELT_BITS
));
1396 /* The stack ptr is used (honorarily) by a CALL insn. */
1397 live
[STACK_POINTER_REGNUM
/ REGSET_ELT_BITS
]
1398 |= (1 << (STACK_POINTER_REGNUM
% REGSET_ELT_BITS
));
1400 /* Calls may also reference any of the global registers,
1401 so they are made live. */
1403 for (i
= 0; i
< FIRST_PSEUDO_REGISTER
; i
++)
1405 live
[i
/ REGSET_ELT_BITS
]
1406 |= (1 << (i
% REGSET_ELT_BITS
));
1408 /* Calls also clobber memory. */
1412 /* Update OLD for the registers used or set. */
1413 for (i
= 0; i
< regset_size
; i
++)
1419 if (GET_CODE (insn
) == CALL_INSN
&& final
)
1421 /* Any regs live at the time of a call instruction
1422 must not go in a register clobbered by calls.
1423 Find all regs now live and record this for them. */
1425 register struct foo
*p
= regs_sometimes_live
;
1427 for (i
= 0; i
< sometimes_max
; i
++, p
++)
1428 if (old
[p
->offset
] & (1 << p
->bit
))
1429 reg_n_calls_crossed
[p
->offset
* REGSET_ELT_BITS
+ p
->bit
]+= 1;
1433 /* On final pass, add any additional sometimes-live regs
1434 into MAXLIVE and REGS_SOMETIMES_LIVE.
1435 Also update counts of how many insns each reg is live at. */
1439 for (i
= 0; i
< regset_size
; i
++)
1441 register int diff
= live
[i
] & ~maxlive
[i
];
1447 for (regno
= 0; diff
&& regno
< REGSET_ELT_BITS
; regno
++)
1448 if (diff
& (1 << regno
))
1450 regs_sometimes_live
[sometimes_max
].offset
= i
;
1451 regs_sometimes_live
[sometimes_max
].bit
= regno
;
1452 diff
&= ~ (1 << regno
);
1459 register struct foo
*p
= regs_sometimes_live
;
1460 for (i
= 0; i
< sometimes_max
; i
++, p
++)
1462 if (old
[p
->offset
] & (1 << p
->bit
))
1463 reg_live_length
[p
->offset
* REGSET_ELT_BITS
+ p
->bit
]++;
1473 if (num_scratch
> max_scratch
)
1474 max_scratch
= num_scratch
;
1477 /* Return 1 if X (the body of an insn, or part of it) is just dead stores
1478 (SET expressions whose destinations are registers dead after the insn).
1479 NEEDED is the regset that says which regs are alive after the insn.
1481 Unless CALL_OK is non-zero, an insn is needed if it contains a CALL. */
1484 insn_dead_p (x
, needed
, call_ok
)
1489 register RTX_CODE code
= GET_CODE (x
);
1490 /* If setting something that's a reg or part of one,
1491 see if that register's altered value will be live. */
1495 register rtx r
= SET_DEST (x
);
1496 /* A SET that is a subroutine call cannot be dead. */
1497 if (! call_ok
&& GET_CODE (SET_SRC (x
)) == CALL
)
1501 if (GET_CODE (r
) == CC0
)
1505 if (GET_CODE (r
) == MEM
&& last_mem_set
&& ! MEM_VOLATILE_P (r
)
1506 && rtx_equal_p (r
, last_mem_set
))
1509 while (GET_CODE (r
) == SUBREG
1510 || GET_CODE (r
) == STRICT_LOW_PART
1511 || GET_CODE (r
) == ZERO_EXTRACT
1512 || GET_CODE (r
) == SIGN_EXTRACT
)
1515 if (GET_CODE (r
) == REG
)
1517 register int regno
= REGNO (r
);
1518 register int offset
= regno
/ REGSET_ELT_BITS
;
1519 register int bit
= 1 << (regno
% REGSET_ELT_BITS
);
1521 if ((regno
< FIRST_PSEUDO_REGISTER
&& global_regs
[regno
])
1522 /* Make sure insns to set frame pointer aren't deleted. */
1523 || regno
== FRAME_POINTER_REGNUM
1524 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
1525 /* Make sure insns to set arg pointer are never deleted
1526 (if the arg pointer isn't fixed, there will be a USE for
1527 it, so we can treat it normally). */
1528 || (regno
== ARG_POINTER_REGNUM
&& fixed_regs
[regno
])
1530 || (needed
[offset
] & bit
) != 0)
1533 /* If this is a hard register, verify that subsequent words are
1535 if (regno
< FIRST_PSEUDO_REGISTER
)
1537 int n
= HARD_REGNO_NREGS (regno
, GET_MODE (r
));
1540 if ((needed
[(regno
+ n
) / REGSET_ELT_BITS
]
1541 & 1 << ((regno
+ n
) % REGSET_ELT_BITS
)) != 0)
1548 /* If performing several activities,
1549 insn is dead if each activity is individually dead.
1550 Also, CLOBBERs and USEs can be ignored; a CLOBBER or USE
1551 that's inside a PARALLEL doesn't make the insn worth keeping. */
1552 else if (code
== PARALLEL
)
1554 register int i
= XVECLEN (x
, 0);
1555 for (i
--; i
>= 0; i
--)
1557 rtx elt
= XVECEXP (x
, 0, i
);
1558 if (!insn_dead_p (elt
, needed
, call_ok
)
1559 && GET_CODE (elt
) != CLOBBER
1560 && GET_CODE (elt
) != USE
)
1565 /* We do not check CLOBBER or USE here.
1566 An insn consisting of just a CLOBBER or just a USE
1567 should not be deleted. */
1571 /* If X is the pattern of the last insn in a libcall, and assuming X is dead,
1572 return 1 if the entire library call is dead.
1573 This is true if X copies a register (hard or pseudo)
1574 and if the hard return reg of the call insn is dead.
1575 (The caller should have tested the destination of X already for death.)
1577 If this insn doesn't just copy a register, then we don't
1578 have an ordinary libcall. In that case, cse could not have
1579 managed to substitute the source for the dest later on,
1580 so we can assume the libcall is dead.
1582 NEEDED is the bit vector of pseudoregs live before this insn.
1583 NOTE is the REG_RETVAL note of the insn. INSN is the insn itself. */
1586 libcall_dead_p (x
, needed
, note
, insn
)
1592 register RTX_CODE code
= GET_CODE (x
);
1596 register rtx r
= SET_SRC (x
);
1597 if (GET_CODE (r
) == REG
)
1599 rtx call
= XEXP (note
, 0);
1602 /* Find the call insn. */
1603 while (call
!= insn
&& GET_CODE (call
) != CALL_INSN
)
1604 call
= NEXT_INSN (call
);
1606 /* If there is none, do nothing special,
1607 since ordinary death handling can understand these insns. */
1611 /* See if the hard reg holding the value is dead.
1612 If this is a PARALLEL, find the call within it. */
1613 call
= PATTERN (call
);
1614 if (GET_CODE (call
) == PARALLEL
)
1616 for (i
= XVECLEN (call
, 0) - 1; i
>= 0; i
--)
1617 if (GET_CODE (XVECEXP (call
, 0, i
)) == SET
1618 && GET_CODE (SET_SRC (XVECEXP (call
, 0, i
))) == CALL
)
1624 call
= XVECEXP (call
, 0, i
);
1627 return insn_dead_p (call
, needed
, 1);
1633 /* Return 1 if register REGNO was used before it was set.
1634 In other words, if it is live at function entry. */
1637 regno_uninitialized (regno
)
1640 if (n_basic_blocks
== 0)
1643 return (basic_block_live_at_start
[0][regno
/ REGSET_ELT_BITS
]
1644 & (1 << (regno
% REGSET_ELT_BITS
)));
1647 /* 1 if register REGNO was alive at a place where `setjmp' was called
1648 and was set more than once or is an argument.
1649 Such regs may be clobbered by `longjmp'. */
1652 regno_clobbered_at_setjmp (regno
)
1655 if (n_basic_blocks
== 0)
1658 return ((reg_n_sets
[regno
] > 1
1659 || (basic_block_live_at_start
[0][regno
/ REGSET_ELT_BITS
]
1660 & (1 << (regno
% REGSET_ELT_BITS
))))
1661 && (regs_live_at_setjmp
[regno
/ REGSET_ELT_BITS
]
1662 & (1 << (regno
% REGSET_ELT_BITS
))));
1665 /* Process the registers that are set within X.
1666 Their bits are set to 1 in the regset DEAD,
1667 because they are dead prior to this insn.
1669 If INSN is nonzero, it is the insn being processed
1670 and the fact that it is nonzero implies this is the FINAL pass
1671 in propagate_block. In this case, various info about register
1672 usage is stored, LOG_LINKS fields of insns are set up. */
1674 static void mark_set_1 ();
1677 mark_set_regs (needed
, dead
, x
, insn
, significant
)
1684 register RTX_CODE code
= GET_CODE (x
);
1686 if (code
== SET
|| code
== CLOBBER
)
1687 mark_set_1 (needed
, dead
, x
, insn
, significant
);
1688 else if (code
== PARALLEL
)
1691 for (i
= XVECLEN (x
, 0) - 1; i
>= 0; i
--)
1693 code
= GET_CODE (XVECEXP (x
, 0, i
));
1694 if (code
== SET
|| code
== CLOBBER
)
1695 mark_set_1 (needed
, dead
, XVECEXP (x
, 0, i
), insn
, significant
);
1700 /* Process a single SET rtx, X. */
1703 mark_set_1 (needed
, dead
, x
, insn
, significant
)
1711 register rtx reg
= SET_DEST (x
);
1713 /* Modifying just one hardware register of a multi-reg value
1714 or just a byte field of a register
1715 does not mean the value from before this insn is now dead.
1716 But it does mean liveness of that register at the end of the block
1719 Within mark_set_1, however, we treat it as if the register is
1720 indeed modified. mark_used_regs will, however, also treat this
1721 register as being used. Thus, we treat these insns as setting a
1722 new value for the register as a function of its old value. This
1723 cases LOG_LINKS to be made appropriately and this will help combine. */
1725 while (GET_CODE (reg
) == SUBREG
|| GET_CODE (reg
) == ZERO_EXTRACT
1726 || GET_CODE (reg
) == SIGN_EXTRACT
1727 || GET_CODE (reg
) == STRICT_LOW_PART
)
1728 reg
= XEXP (reg
, 0);
1730 /* If we are writing into memory or into a register mentioned in the
1731 address of the last thing stored into memory, show we don't know
1732 what the last store was. If we are writing memory, save the address
1733 unless it is volatile. */
1734 if (GET_CODE (reg
) == MEM
1735 || (GET_CODE (reg
) == REG
1736 && last_mem_set
!= 0 && reg_overlap_mentioned_p (reg
, last_mem_set
)))
1739 if (GET_CODE (reg
) == MEM
&& ! side_effects_p (reg
)
1740 /* There are no REG_INC notes for SP, so we can't assume we'll see
1741 everything that invalidates it. To be safe, don't eliminate any
1742 stores though SP; none of them should be redundant anyway. */
1743 && ! reg_mentioned_p (stack_pointer_rtx
, reg
))
1746 if (GET_CODE (reg
) == REG
1747 && (regno
= REGNO (reg
), regno
!= FRAME_POINTER_REGNUM
)
1748 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
1749 && ! (regno
== ARG_POINTER_REGNUM
&& fixed_regs
[regno
])
1751 && ! (regno
< FIRST_PSEUDO_REGISTER
&& global_regs
[regno
]))
1752 /* && regno != STACK_POINTER_REGNUM) -- let's try without this. */
1754 register int offset
= regno
/ REGSET_ELT_BITS
;
1755 register int bit
= 1 << (regno
% REGSET_ELT_BITS
);
1756 int all_needed
= (needed
[offset
] & bit
) != 0;
1757 int some_needed
= (needed
[offset
] & bit
) != 0;
1759 /* Mark it as a significant register for this basic block. */
1761 significant
[offset
] |= bit
;
1763 /* Mark it as as dead before this insn. */
1764 dead
[offset
] |= bit
;
1766 /* A hard reg in a wide mode may really be multiple registers.
1767 If so, mark all of them just like the first. */
1768 if (regno
< FIRST_PSEUDO_REGISTER
)
1772 /* Nothing below is needed for the stack pointer; get out asap.
1773 Eg, log links aren't needed, since combine won't use them. */
1774 if (regno
== STACK_POINTER_REGNUM
)
1777 n
= HARD_REGNO_NREGS (regno
, GET_MODE (reg
));
1781 significant
[(regno
+ n
) / REGSET_ELT_BITS
]
1782 |= 1 << ((regno
+ n
) % REGSET_ELT_BITS
);
1783 dead
[(regno
+ n
) / REGSET_ELT_BITS
]
1784 |= 1 << ((regno
+ n
) % REGSET_ELT_BITS
);
1785 some_needed
|= (needed
[(regno
+ n
) / REGSET_ELT_BITS
]
1786 & 1 << ((regno
+ n
) % REGSET_ELT_BITS
));
1787 all_needed
&= (needed
[(regno
+ n
) / REGSET_ELT_BITS
]
1788 & 1 << ((regno
+ n
) % REGSET_ELT_BITS
));
1791 /* Additional data to record if this is the final pass. */
1794 register rtx y
= reg_next_use
[regno
];
1795 register int blocknum
= BLOCK_NUM (insn
);
1797 /* If this is a hard reg, record this function uses the reg. */
1799 if (regno
< FIRST_PSEUDO_REGISTER
)
1802 int endregno
= regno
+ HARD_REGNO_NREGS (regno
, GET_MODE (reg
));
1804 for (i
= regno
; i
< endregno
; i
++)
1806 regs_ever_live
[i
] = 1;
1812 /* Keep track of which basic blocks each reg appears in. */
1814 if (reg_basic_block
[regno
] == REG_BLOCK_UNKNOWN
)
1815 reg_basic_block
[regno
] = blocknum
;
1816 else if (reg_basic_block
[regno
] != blocknum
)
1817 reg_basic_block
[regno
] = REG_BLOCK_GLOBAL
;
1819 /* Count (weighted) references, stores, etc. This counts a
1820 register twice if it is modified, but that is correct. */
1821 reg_n_sets
[regno
]++;
1823 reg_n_refs
[regno
] += loop_depth
;
1825 /* The insns where a reg is live are normally counted
1826 elsewhere, but we want the count to include the insn
1827 where the reg is set, and the normal counting mechanism
1828 would not count it. */
1829 reg_live_length
[regno
]++;
1832 /* The next use is no longer "next", since a store intervenes. */
1833 reg_next_use
[regno
] = 0;
1837 /* Make a logical link from the next following insn
1838 that uses this register, back to this insn.
1839 The following insns have already been processed.
1841 We don't build a LOG_LINK for hard registers containing
1842 in ASM_OPERANDs. If these registers get replaced,
1843 we might wind up changing the semantics of the insn,
1844 even if reload can make what appear to be valid assignments
1846 if (y
&& (BLOCK_NUM (y
) == blocknum
)
1847 && (regno
>= FIRST_PSEUDO_REGISTER
1848 || asm_noperands (PATTERN (y
)) < 0))
1850 = gen_rtx (INSN_LIST
, VOIDmode
, insn
, LOG_LINKS (y
));
1852 else if (! some_needed
)
1854 /* Note that dead stores have already been deleted when possible
1855 If we get here, we have found a dead store that cannot
1856 be eliminated (because the same insn does something useful).
1857 Indicate this by marking the reg being set as dying here. */
1859 = gen_rtx (EXPR_LIST
, REG_UNUSED
, reg
, REG_NOTES (insn
));
1860 reg_n_deaths
[REGNO (reg
)]++;
1864 /* This is a case where we have a multi-word hard register
1865 and some, but not all, of the words of the register are
1866 needed in subsequent insns. Write REG_UNUSED notes
1867 for those parts that were not needed. This case should
1872 for (i
= HARD_REGNO_NREGS (regno
, GET_MODE (reg
)) - 1;
1874 if ((needed
[(regno
+ i
) / REGSET_ELT_BITS
]
1875 & 1 << ((regno
+ i
) % REGSET_ELT_BITS
)) == 0)
1877 = gen_rtx (EXPR_LIST
, REG_UNUSED
,
1878 gen_rtx (REG
, word_mode
, regno
+ i
),
1884 /* If this is the last pass and this is a SCRATCH, show it will be dying
1885 here and count it. */
1886 else if (GET_CODE (reg
) == SCRATCH
&& insn
!= 0)
1889 = gen_rtx (EXPR_LIST
, REG_UNUSED
, reg
, REG_NOTES (insn
));
1896 /* X is a MEM found in INSN. See if we can convert it into an auto-increment
1900 find_auto_inc (needed
, x
, insn
)
1905 rtx addr
= XEXP (x
, 0);
1908 /* Here we detect use of an index register which might be good for
1909 postincrement, postdecrement, preincrement, or predecrement. */
1911 if (GET_CODE (addr
) == PLUS
&& GET_CODE (XEXP (addr
, 1)) == CONST_INT
)
1912 offset
= INTVAL (XEXP (addr
, 1)), addr
= XEXP (addr
, 0);
1914 if (GET_CODE (addr
) == REG
)
1917 register int size
= GET_MODE_SIZE (GET_MODE (x
));
1920 int regno
= REGNO (addr
);
1922 /* Is the next use an increment that might make auto-increment? */
1923 incr
= reg_next_use
[regno
];
1924 if (incr
&& GET_CODE (PATTERN (incr
)) == SET
1925 && BLOCK_NUM (incr
) == BLOCK_NUM (insn
)
1926 /* Can't add side effects to jumps; if reg is spilled and
1927 reloaded, there's no way to store back the altered value. */
1928 && GET_CODE (insn
) != JUMP_INSN
1929 && (y
= SET_SRC (PATTERN (incr
)), GET_CODE (y
) == PLUS
)
1930 && XEXP (y
, 0) == addr
1931 && GET_CODE (XEXP (y
, 1)) == CONST_INT
1933 #ifdef HAVE_POST_INCREMENT
1934 || (INTVAL (XEXP (y
, 1)) == size
&& offset
== 0)
1936 #ifdef HAVE_POST_DECREMENT
1937 || (INTVAL (XEXP (y
, 1)) == - size
&& offset
== 0)
1939 #ifdef HAVE_PRE_INCREMENT
1940 || (INTVAL (XEXP (y
, 1)) == size
&& offset
== size
)
1942 #ifdef HAVE_PRE_DECREMENT
1943 || (INTVAL (XEXP (y
, 1)) == - size
&& offset
== - size
)
1946 /* Make sure this reg appears only once in this insn. */
1947 && (use
= find_use_as_address (PATTERN (insn
), addr
, offset
),
1948 use
!= 0 && use
!= (rtx
) 1))
1951 rtx q
= SET_DEST (PATTERN (incr
));
1953 if (dead_or_set_p (incr
, addr
))
1955 else if (GET_CODE (q
) == REG
&& ! reg_used_between_p (q
, insn
, incr
))
1957 /* We have *p followed by q = p+size.
1958 Both p and q must be live afterward,
1959 and q must be dead before.
1960 Change it to q = p, ...*q..., q = q+size.
1961 Then fall into the usual case. */
1965 emit_move_insn (q
, addr
);
1966 insns
= get_insns ();
1969 /* If anything in INSNS have UID's that don't fit within the
1970 extra space we allocate earlier, we can't make this auto-inc.
1971 This should never happen. */
1972 for (temp
= insns
; temp
; temp
= NEXT_INSN (temp
))
1974 if (INSN_UID (temp
) > max_uid_for_flow
)
1976 BLOCK_NUM (temp
) = BLOCK_NUM (insn
);
1979 emit_insns_before (insns
, insn
);
1981 if (basic_block_head
[BLOCK_NUM (insn
)] == insn
)
1982 basic_block_head
[BLOCK_NUM (insn
)] = insns
;
1987 /* INCR will become a NOTE and INSN won't contain a
1988 use of ADDR. If a use of ADDR was just placed in
1989 the insn before INSN, make that the next use.
1990 Otherwise, invalidate it. */
1991 if (GET_CODE (PREV_INSN (insn
)) == INSN
1992 && GET_CODE (PATTERN (PREV_INSN (insn
))) == SET
1993 && SET_SRC (PATTERN (PREV_INSN (insn
))) == addr
)
1994 reg_next_use
[regno
] = PREV_INSN (insn
);
1996 reg_next_use
[regno
] = 0;
2002 /* REGNO is now used in INCR which is below INSN, but
2003 it previously wasn't live here. If we don't mark
2004 it as needed, we'll put a REG_DEAD note for it
2005 on this insn, which is incorrect. */
2006 needed
[regno
/ REGSET_ELT_BITS
]
2007 |= 1 << (regno
% REGSET_ELT_BITS
);
2009 /* If there are any calls between INSN and INCR, show
2010 that REGNO now crosses them. */
2011 for (temp
= insn
; temp
!= incr
; temp
= NEXT_INSN (temp
))
2012 if (GET_CODE (temp
) == CALL_INSN
)
2013 reg_n_calls_crossed
[regno
]++;
2018 /* We have found a suitable auto-increment: do POST_INC around
2019 the register here, and patch out the increment instruction
2021 XEXP (x
, 0) = gen_rtx ((INTVAL (XEXP (y
, 1)) == size
2022 ? (offset
? PRE_INC
: POST_INC
)
2023 : (offset
? PRE_DEC
: POST_DEC
)),
2026 /* Record that this insn has an implicit side effect. */
2028 = gen_rtx (EXPR_LIST
, REG_INC
, addr
, REG_NOTES (insn
));
2030 /* Modify the old increment-insn to simply copy
2031 the already-incremented value of our register. */
2032 SET_SRC (PATTERN (incr
)) = addr
;
2033 /* Indicate insn must be re-recognized. */
2034 INSN_CODE (incr
) = -1;
2036 /* If that makes it a no-op (copying the register into itself)
2037 then delete it so it won't appear to be a "use" and a "set"
2038 of this register. */
2039 if (SET_DEST (PATTERN (incr
)) == addr
)
2041 PUT_CODE (incr
, NOTE
);
2042 NOTE_LINE_NUMBER (incr
) = NOTE_INSN_DELETED
;
2043 NOTE_SOURCE_FILE (incr
) = 0;
2046 if (regno
>= FIRST_PSEUDO_REGISTER
)
2048 /* Count an extra reference to the reg. When a reg is
2049 incremented, spilling it is worse, so we want to make
2050 that less likely. */
2051 reg_n_refs
[regno
] += loop_depth
;
2052 /* Count the increment as a setting of the register,
2053 even though it isn't a SET in rtl. */
2054 reg_n_sets
[regno
]++;
2060 #endif /* AUTO_INC_DEC */
2062 /* Scan expression X and store a 1-bit in LIVE for each reg it uses.
2063 This is done assuming the registers needed from X
2064 are those that have 1-bits in NEEDED.
2066 On the final pass, FINAL is 1. This means try for autoincrement
2067 and count the uses and deaths of each pseudo-reg.
2069 INSN is the containing instruction. If INSN is dead, this function is not
2073 mark_used_regs (needed
, live
, x
, final
, insn
)
2080 register RTX_CODE code
;
2085 code
= GET_CODE (x
);
2107 /* Invalidate the data for the last MEM stored. We could do this only
2108 if the addresses conflict, but this doesn't seem worthwhile. */
2113 find_auto_inc (needed
, x
, insn
);
2118 /* See a register other than being set
2119 => mark it as needed. */
2123 register int offset
= regno
/ REGSET_ELT_BITS
;
2124 register int bit
= 1 << (regno
% REGSET_ELT_BITS
);
2125 int all_needed
= (needed
[offset
] & bit
) != 0;
2126 int some_needed
= (needed
[offset
] & bit
) != 0;
2128 live
[offset
] |= bit
;
2129 /* A hard reg in a wide mode may really be multiple registers.
2130 If so, mark all of them just like the first. */
2131 if (regno
< FIRST_PSEUDO_REGISTER
)
2135 /* For stack ptr or fixed arg pointer,
2136 nothing below can be necessary, so waste no more time. */
2137 if (regno
== STACK_POINTER_REGNUM
2138 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
2139 || (regno
== ARG_POINTER_REGNUM
&& fixed_regs
[regno
])
2141 || regno
== FRAME_POINTER_REGNUM
)
2143 /* If this is a register we are going to try to eliminate,
2144 don't mark it live here. If we are successful in
2145 eliminating it, it need not be live unless it is used for
2146 pseudos, in which case it will have been set live when
2147 it was allocated to the pseudos. If the register will not
2148 be eliminated, reload will set it live at that point. */
2150 if (! TEST_HARD_REG_BIT (elim_reg_set
, regno
))
2151 regs_ever_live
[regno
] = 1;
2154 /* No death notes for global register variables;
2155 their values are live after this function exits. */
2156 if (global_regs
[regno
])
2159 n
= HARD_REGNO_NREGS (regno
, GET_MODE (x
));
2162 live
[(regno
+ n
) / REGSET_ELT_BITS
]
2163 |= 1 << ((regno
+ n
) % REGSET_ELT_BITS
);
2164 some_needed
|= (needed
[(regno
+ n
) / REGSET_ELT_BITS
]
2165 & 1 << ((regno
+ n
) % REGSET_ELT_BITS
));
2166 all_needed
&= (needed
[(regno
+ n
) / REGSET_ELT_BITS
]
2167 & 1 << ((regno
+ n
) % REGSET_ELT_BITS
));
2172 /* Record where each reg is used, so when the reg
2173 is set we know the next insn that uses it. */
2175 reg_next_use
[regno
] = insn
;
2177 if (regno
< FIRST_PSEUDO_REGISTER
)
2179 /* If a hard reg is being used,
2180 record that this function does use it. */
2182 i
= HARD_REGNO_NREGS (regno
, GET_MODE (x
));
2186 regs_ever_live
[regno
+ --i
] = 1;
2191 /* Keep track of which basic block each reg appears in. */
2193 register int blocknum
= BLOCK_NUM (insn
);
2195 if (reg_basic_block
[regno
] == REG_BLOCK_UNKNOWN
)
2196 reg_basic_block
[regno
] = blocknum
;
2197 else if (reg_basic_block
[regno
] != blocknum
)
2198 reg_basic_block
[regno
] = REG_BLOCK_GLOBAL
;
2200 /* Count (weighted) number of uses of each reg. */
2202 reg_n_refs
[regno
] += loop_depth
;
2205 /* Record and count the insns in which a reg dies.
2206 If it is used in this insn and was dead below the insn
2207 then it dies in this insn. If it was set in this insn,
2208 we do not make a REG_DEAD note; likewise if we already
2209 made such a note. */
2212 && ! dead_or_set_p (insn
, x
)
2214 && (regno
>= FIRST_PSEUDO_REGISTER
|| ! fixed_regs
[regno
])
2218 /* If none of the words in X is needed, make a REG_DEAD
2219 note. Otherwise, we must make partial REG_DEAD notes. */
2223 = gen_rtx (EXPR_LIST
, REG_DEAD
, x
, REG_NOTES (insn
));
2224 reg_n_deaths
[regno
]++;
2230 /* Don't make a REG_DEAD note for a part of a register
2231 that is set in the insn. */
2233 for (i
= HARD_REGNO_NREGS (regno
, GET_MODE (x
)) - 1;
2235 if ((needed
[(regno
+ i
) / REGSET_ELT_BITS
]
2236 & 1 << ((regno
+ i
) % REGSET_ELT_BITS
)) == 0
2237 && ! dead_or_set_regno_p (insn
, regno
+ i
))
2239 = gen_rtx (EXPR_LIST
, REG_DEAD
,
2240 gen_rtx (REG
, word_mode
, regno
+ i
),
2250 register rtx testreg
= SET_DEST (x
);
2253 /* If storing into MEM, don't show it as being used. But do
2254 show the address as being used. */
2255 if (GET_CODE (testreg
) == MEM
)
2259 find_auto_inc (needed
, testreg
, insn
);
2261 mark_used_regs (needed
, live
, XEXP (testreg
, 0), final
, insn
);
2262 mark_used_regs (needed
, live
, SET_SRC (x
), final
, insn
);
2266 /* Storing in STRICT_LOW_PART is like storing in a reg
2267 in that this SET might be dead, so ignore it in TESTREG.
2268 but in some other ways it is like using the reg.
2270 Storing in a SUBREG or a bit field is like storing the entire
2271 register in that if the register's value is not used
2272 then this SET is not needed. */
2273 while (GET_CODE (testreg
) == STRICT_LOW_PART
2274 || GET_CODE (testreg
) == ZERO_EXTRACT
2275 || GET_CODE (testreg
) == SIGN_EXTRACT
2276 || GET_CODE (testreg
) == SUBREG
)
2278 /* Modifying a single register in an alternate mode
2279 does not use any of the old value. But these other
2280 ways of storing in a register do use the old value. */
2281 if (GET_CODE (testreg
) == SUBREG
2282 && !(REG_SIZE (SUBREG_REG (testreg
)) > REG_SIZE (testreg
)))
2287 testreg
= XEXP (testreg
, 0);
2290 /* If this is a store into a register,
2291 recursively scan the value being stored. */
2293 if (GET_CODE (testreg
) == REG
2294 && (regno
= REGNO (testreg
), regno
!= FRAME_POINTER_REGNUM
)
2295 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
2296 && ! (regno
== ARG_POINTER_REGNUM
&& fixed_regs
[regno
])
2298 && ! (regno
< FIRST_PSEUDO_REGISTER
&& global_regs
[regno
]))
2300 mark_used_regs (needed
, live
, SET_SRC (x
), final
, insn
);
2302 mark_used_regs (needed
, live
, SET_DEST (x
), final
, insn
);
2309 /* If exiting needs the right stack value, consider this insn as
2310 using the stack pointer. In any event, consider it as using
2311 all global registers. */
2313 #ifdef EXIT_IGNORE_STACK
2314 if (! EXIT_IGNORE_STACK
2315 || (! FRAME_POINTER_REQUIRED
&& flag_omit_frame_pointer
))
2317 live
[STACK_POINTER_REGNUM
/ REGSET_ELT_BITS
]
2318 |= 1 << (STACK_POINTER_REGNUM
% REGSET_ELT_BITS
);
2320 for (i
= 0; i
< FIRST_PSEUDO_REGISTER
; i
++)
2322 live
[i
/ REGSET_ELT_BITS
] |= 1 << (i
% REGSET_ELT_BITS
);
2326 /* Recursively scan the operands of this expression. */
2329 register char *fmt
= GET_RTX_FORMAT (code
);
2332 for (i
= GET_RTX_LENGTH (code
) - 1; i
>= 0; i
--)
2336 /* Tail recursive case: save a function call level. */
2342 mark_used_regs (needed
, live
, XEXP (x
, i
), final
, insn
);
2344 else if (fmt
[i
] == 'E')
2347 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
2348 mark_used_regs (needed
, live
, XVECEXP (x
, i
, j
), final
, insn
);
2357 try_pre_increment_1 (insn
)
2360 /* Find the next use of this reg. If in same basic block,
2361 make it do pre-increment or pre-decrement if appropriate. */
2362 rtx x
= PATTERN (insn
);
2363 int amount
= ((GET_CODE (SET_SRC (x
)) == PLUS
? 1 : -1)
2364 * INTVAL (XEXP (SET_SRC (x
), 1)));
2365 int regno
= REGNO (SET_DEST (x
));
2366 rtx y
= reg_next_use
[regno
];
2368 && BLOCK_NUM (y
) == BLOCK_NUM (insn
)
2369 && try_pre_increment (y
, SET_DEST (PATTERN (insn
)),
2372 /* We have found a suitable auto-increment
2373 and already changed insn Y to do it.
2374 So flush this increment-instruction. */
2375 PUT_CODE (insn
, NOTE
);
2376 NOTE_LINE_NUMBER (insn
) = NOTE_INSN_DELETED
;
2377 NOTE_SOURCE_FILE (insn
) = 0;
2378 /* Count a reference to this reg for the increment
2379 insn we are deleting. When a reg is incremented.
2380 spilling it is worse, so we want to make that
2382 if (regno
>= FIRST_PSEUDO_REGISTER
)
2384 reg_n_refs
[regno
] += loop_depth
;
2385 reg_n_sets
[regno
]++;
2392 /* Try to change INSN so that it does pre-increment or pre-decrement
2393 addressing on register REG in order to add AMOUNT to REG.
2394 AMOUNT is negative for pre-decrement.
2395 Returns 1 if the change could be made.
2396 This checks all about the validity of the result of modifying INSN. */
2399 try_pre_increment (insn
, reg
, amount
)
2405 /* Nonzero if we can try to make a pre-increment or pre-decrement.
2406 For example, addl $4,r1; movl (r1),... can become movl +(r1),... */
2408 /* Nonzero if we can try to make a post-increment or post-decrement.
2409 For example, addl $4,r1; movl -4(r1),... can become movl (r1)+,...
2410 It is possible for both PRE_OK and POST_OK to be nonzero if the machine
2411 supports both pre-inc and post-inc, or both pre-dec and post-dec. */
2414 /* Nonzero if the opportunity actually requires post-inc or post-dec. */
2417 /* From the sign of increment, see which possibilities are conceivable
2418 on this target machine. */
2419 #ifdef HAVE_PRE_INCREMENT
2423 #ifdef HAVE_POST_INCREMENT
2428 #ifdef HAVE_PRE_DECREMENT
2432 #ifdef HAVE_POST_DECREMENT
2437 if (! (pre_ok
|| post_ok
))
2440 /* It is not safe to add a side effect to a jump insn
2441 because if the incremented register is spilled and must be reloaded
2442 there would be no way to store the incremented value back in memory. */
2444 if (GET_CODE (insn
) == JUMP_INSN
)
2449 use
= find_use_as_address (PATTERN (insn
), reg
, 0);
2450 if (post_ok
&& (use
== 0 || use
== (rtx
) 1))
2452 use
= find_use_as_address (PATTERN (insn
), reg
, -amount
);
2456 if (use
== 0 || use
== (rtx
) 1)
2459 if (GET_MODE_SIZE (GET_MODE (use
)) != (amount
> 0 ? amount
: - amount
))
2462 XEXP (use
, 0) = gen_rtx (amount
> 0
2463 ? (do_post
? POST_INC
: PRE_INC
)
2464 : (do_post
? POST_DEC
: PRE_DEC
),
2467 /* Record that this insn now has an implicit side effect on X. */
2468 REG_NOTES (insn
) = gen_rtx (EXPR_LIST
, REG_INC
, reg
, REG_NOTES (insn
));
2472 #endif /* AUTO_INC_DEC */
2474 /* Find the place in the rtx X where REG is used as a memory address.
2475 Return the MEM rtx that so uses it.
2476 If PLUSCONST is nonzero, search instead for a memory address equivalent to
2477 (plus REG (const_int PLUSCONST)).
2479 If such an address does not appear, return 0.
2480 If REG appears more than once, or is used other than in such an address,
2484 find_use_as_address (x
, reg
, plusconst
)
2489 enum rtx_code code
= GET_CODE (x
);
2490 char *fmt
= GET_RTX_FORMAT (code
);
2492 register rtx value
= 0;
2495 if (code
== MEM
&& XEXP (x
, 0) == reg
&& plusconst
== 0)
2498 if (code
== MEM
&& GET_CODE (XEXP (x
, 0)) == PLUS
2499 && XEXP (XEXP (x
, 0), 0) == reg
2500 && GET_CODE (XEXP (XEXP (x
, 0), 1)) == CONST_INT
2501 && INTVAL (XEXP (XEXP (x
, 0), 1)) == plusconst
)
2504 if (code
== SIGN_EXTRACT
|| code
== ZERO_EXTRACT
)
2506 /* If REG occurs inside a MEM used in a bit-field reference,
2507 that is unacceptable. */
2508 if (find_use_as_address (XEXP (x
, 0), reg
, 0) != 0)
2515 for (i
= GET_RTX_LENGTH (code
) - 1; i
>= 0; i
--)
2519 tem
= find_use_as_address (XEXP (x
, i
), reg
, plusconst
);
2528 for (j
= XVECLEN (x
, i
) - 1; j
>= 0; j
--)
2530 tem
= find_use_as_address (XVECEXP (x
, i
, j
), reg
, plusconst
);
2542 /* Write information about registers and basic blocks into FILE.
2543 This is part of making a debugging dump. */
2546 dump_flow_info (file
)
2550 static char *reg_class_names
[] = REG_CLASS_NAMES
;
2552 fprintf (file
, "%d registers.\n", max_regno
);
2554 for (i
= FIRST_PSEUDO_REGISTER
; i
< max_regno
; i
++)
2557 enum reg_class
class;
2558 fprintf (file
, "\nRegister %d used %d times across %d insns",
2559 i
, reg_n_refs
[i
], reg_live_length
[i
]);
2560 if (reg_basic_block
[i
] >= 0)
2561 fprintf (file
, " in block %d", reg_basic_block
[i
]);
2562 if (reg_n_deaths
[i
] != 1)
2563 fprintf (file
, "; dies in %d places", reg_n_deaths
[i
]);
2564 if (reg_n_calls_crossed
[i
] == 1)
2565 fprintf (file
, "; crosses 1 call");
2566 else if (reg_n_calls_crossed
[i
])
2567 fprintf (file
, "; crosses %d calls", reg_n_calls_crossed
[i
]);
2568 if (PSEUDO_REGNO_BYTES (i
) != UNITS_PER_WORD
)
2569 fprintf (file
, "; %d bytes", PSEUDO_REGNO_BYTES (i
));
2570 class = reg_preferred_class (i
);
2571 if (class != GENERAL_REGS
)
2573 if (reg_preferred_or_nothing (i
))
2574 fprintf (file
, "; %s or none", reg_class_names
[(int) class]);
2576 fprintf (file
, "; pref %s", reg_class_names
[(int) class]);
2578 if (REGNO_POINTER_FLAG (i
))
2579 fprintf (file
, "; pointer");
2580 fprintf (file
, ".\n");
2582 fprintf (file
, "\n%d basic blocks.\n", n_basic_blocks
);
2583 for (i
= 0; i
< n_basic_blocks
; i
++)
2585 register rtx head
, jump
;
2587 fprintf (file
, "\nBasic block %d: first insn %d, last %d.\n",
2589 INSN_UID (basic_block_head
[i
]),
2590 INSN_UID (basic_block_end
[i
]));
2591 /* The control flow graph's storage is freed
2592 now when flow_analysis returns.
2593 Don't try to print it if it is gone. */
2594 if (basic_block_drops_in
)
2596 fprintf (file
, "Reached from blocks: ");
2597 head
= basic_block_head
[i
];
2598 if (GET_CODE (head
) == CODE_LABEL
)
2599 for (jump
= LABEL_REFS (head
);
2601 jump
= LABEL_NEXTREF (jump
))
2603 register int from_block
= BLOCK_NUM (CONTAINING_INSN (jump
));
2604 fprintf (file
, " %d", from_block
);
2606 if (basic_block_drops_in
[i
])
2607 fprintf (file
, " previous");
2609 fprintf (file
, "\nRegisters live at start:");
2610 for (regno
= 0; regno
< max_regno
; regno
++)
2612 register int offset
= regno
/ REGSET_ELT_BITS
;
2613 register int bit
= 1 << (regno
% REGSET_ELT_BITS
);
2614 if (basic_block_live_at_start
[i
][offset
] & bit
)
2615 fprintf (file
, " %d", regno
);
2617 fprintf (file
, "\n");
2619 fprintf (file
, "\n");