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1.1 root 1: /* Data flow analysis for GNU compiler.
2: Copyright (C) 1987, 1988, 1992, 1993 Free Software Foundation, Inc.
3:
4: This file is part of GNU CC.
5:
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)
9: any later version.
10:
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.
15:
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. */
19:
20:
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.
25:
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.
29:
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.
33:
34: ** find_basic_blocks **
35:
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.
40:
41: find_basic_blocks also finds any unreachable loops
42: and deletes them.
43:
44: ** life_analysis **
45:
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.
49:
50: ** live-register info **
51:
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.
54:
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
58: of the basic block.
59:
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).
66:
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
76: REG_DEAD notes.
77:
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.
84:
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.
88:
89: ** Other actions of life_analysis **
90:
91: life_analysis sets up the LOG_LINKS fields of insns because the
92: information needed to do so is readily available.
93:
94: life_analysis deletes insns whose only effect is to store a value
95: that is never used.
96:
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.
102:
103: Each time an incrementing or decrementing address is created,
104: a REG_INC element is added to the insn's REG_NOTES list.
105:
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. */
109:
110: #include <stdio.h>
111: #include "config.h"
112: #include "rtl.h"
113: #include "basic-block.h"
114: #include "insn-config.h"
115: #include "regs.h"
116: #include "hard-reg-set.h"
117: #include "flags.h"
118: #include "output.h"
119:
120: #include "obstack.h"
121: #define obstack_chunk_alloc xmalloc
122: #define obstack_chunk_free free
123:
124: /* List of labels that must never be deleted. */
125: extern rtx forced_labels;
126:
127: /* Get the basic block number of an insn.
128: This info should not be expected to remain available
129: after the end of life_analysis. */
130:
131: /* This is the limit of the allocated space in the following two arrays. */
132:
133: static int max_uid_for_flow;
134:
135: #define BLOCK_NUM(INSN) uid_block_number[INSN_UID (INSN)]
136:
137: /* This is where the BLOCK_NUM values are really stored.
138: This is set up by find_basic_blocks and used there and in life_analysis,
139: and then freed. */
140:
141: static int *uid_block_number;
142:
143: /* INSN_VOLATILE (insn) is 1 if the insn refers to anything volatile. */
144:
145: #define INSN_VOLATILE(INSN) uid_volatile[INSN_UID (INSN)]
146: static char *uid_volatile;
147:
148: /* Number of basic blocks in the current function. */
149:
150: int n_basic_blocks;
151:
152: /* Maximum register number used in this function, plus one. */
153:
154: int max_regno;
155:
156: /* Maximum number of SCRATCH rtx's used in any basic block of this function. */
157:
158: int max_scratch;
159:
160: /* Number of SCRATCH rtx's in the current block. */
161:
162: static int num_scratch;
163:
164: /* Indexed by n, gives number of basic block that (REG n) is used in.
165: If the value is REG_BLOCK_GLOBAL (-2),
166: it means (REG n) is used in more than one basic block.
167: REG_BLOCK_UNKNOWN (-1) means it hasn't been seen yet so we don't know.
168: This information remains valid for the rest of the compilation
169: of the current function; it is used to control register allocation. */
170:
171: int *reg_basic_block;
172:
173: /* Indexed by n, gives number of times (REG n) is used or set, each
174: weighted by its loop-depth.
175: This information remains valid for the rest of the compilation
176: of the current function; it is used to control register allocation. */
177:
178: int *reg_n_refs;
179:
180: /* Indexed by N, gives number of places register N dies.
181: This information remains valid for the rest of the compilation
182: of the current function; it is used to control register allocation. */
183:
184: short *reg_n_deaths;
185:
186: /* Indexed by N, gives 1 if that reg is live across any CALL_INSNs.
187: This information remains valid for the rest of the compilation
188: of the current function; it is used to control register allocation. */
189:
190: int *reg_n_calls_crossed;
191:
192: /* Total number of instructions at which (REG n) is live.
193: The larger this is, the less priority (REG n) gets for
194: allocation in a real register.
195: This information remains valid for the rest of the compilation
196: of the current function; it is used to control register allocation.
197:
198: local-alloc.c may alter this number to change the priority.
199:
200: Negative values are special.
201: -1 is used to mark a pseudo reg which has a constant or memory equivalent
202: and is used infrequently enough that it should not get a hard register.
203: -2 is used to mark a pseudo reg for a parameter, when a frame pointer
204: is not required. global.c makes an allocno for this but does
205: not try to assign a hard register to it. */
206:
207: int *reg_live_length;
208:
209: /* Element N is the next insn that uses (hard or pseudo) register number N
210: within the current basic block; or zero, if there is no such insn.
211: This is valid only during the final backward scan in propagate_block. */
212:
213: static rtx *reg_next_use;
214:
215: /* Size of a regset for the current function,
216: in (1) bytes and (2) elements. */
217:
218: int regset_bytes;
219: int regset_size;
220:
221: /* Element N is first insn in basic block N.
222: This info lasts until we finish compiling the function. */
223:
224: rtx *basic_block_head;
225:
226: /* Element N is last insn in basic block N.
227: This info lasts until we finish compiling the function. */
228:
229: rtx *basic_block_end;
230:
231: /* Element N is a regset describing the registers live
232: at the start of basic block N.
233: This info lasts until we finish compiling the function. */
234:
235: regset *basic_block_live_at_start;
236:
237: /* Regset of regs live when calls to `setjmp'-like functions happen. */
238:
239: regset regs_live_at_setjmp;
240:
241: /* List made of EXPR_LIST rtx's which gives pairs of pseudo registers
242: that have to go in the same hard reg.
243: The first two regs in the list are a pair, and the next two
244: are another pair, etc. */
245: rtx regs_may_share;
246:
247: /* Element N is nonzero if control can drop into basic block N
248: from the preceding basic block. Freed after life_analysis. */
249:
250: static char *basic_block_drops_in;
251:
252: /* Element N is depth within loops of the last insn in basic block number N.
253: Freed after life_analysis. */
254:
255: static short *basic_block_loop_depth;
256:
257: /* Element N nonzero if basic block N can actually be reached.
258: Vector exists only during find_basic_blocks. */
259:
260: static char *block_live_static;
261:
262: /* Depth within loops of basic block being scanned for lifetime analysis,
263: plus one. This is the weight attached to references to registers. */
264:
265: static int loop_depth;
266:
267: /* During propagate_block, this is non-zero if the value of CC0 is live. */
268:
269: static int cc0_live;
270:
271: /* During propagate_block, this contains the last MEM stored into. It
272: is used to eliminate consecutive stores to the same location. */
273:
274: static rtx last_mem_set;
275:
276: /* Set of registers that may be eliminable. These are handled specially
277: in updating regs_ever_live. */
278:
279: static HARD_REG_SET elim_reg_set;
280:
281: /* Forward declarations */
282: static void find_basic_blocks ();
283: static void life_analysis ();
284: static void mark_label_ref ();
285: void allocate_for_life_analysis (); /* Used also in stupid_life_analysis */
286: static void init_regset_vector ();
287: static void propagate_block ();
288: static void mark_set_regs ();
289: static void mark_used_regs ();
290: static int insn_dead_p ();
291: static int libcall_dead_p ();
292: static int try_pre_increment ();
293: static int try_pre_increment_1 ();
294: static rtx find_use_as_address ();
295: void dump_flow_info ();
296:
297: /* Find basic blocks of the current function and perform data flow analysis.
298: F is the first insn of the function and NREGS the number of register numbers
299: in use. */
300:
301: void
302: flow_analysis (f, nregs, file)
303: rtx f;
304: int nregs;
305: FILE *file;
306: {
307: register rtx insn;
308: register int i;
309: rtx nonlocal_label_list = nonlocal_label_rtx_list ();
310:
311: #ifdef ELIMINABLE_REGS
312: static struct {int from, to; } eliminables[] = ELIMINABLE_REGS;
313: #endif
314:
315: /* Record which registers will be eliminated. We use this in
316: mark_used_regs. */
317:
318: CLEAR_HARD_REG_SET (elim_reg_set);
319:
320: #ifdef ELIMINABLE_REGS
321: for (i = 0; i < sizeof eliminables / sizeof eliminables[0]; i++)
322: SET_HARD_REG_BIT (elim_reg_set, eliminables[i].from);
323: #else
324: SET_HARD_REG_BIT (elim_reg_set, FRAME_POINTER_REGNUM);
325: #endif
326:
327: /* Count the basic blocks. Also find maximum insn uid value used. */
328:
329: {
330: register RTX_CODE prev_code = JUMP_INSN;
331: register RTX_CODE code;
332:
333: max_uid_for_flow = 0;
334:
335: for (insn = f, i = 0; insn; insn = NEXT_INSN (insn))
336: {
337: code = GET_CODE (insn);
338: if (INSN_UID (insn) > max_uid_for_flow)
339: max_uid_for_flow = INSN_UID (insn);
340: if (code == CODE_LABEL
341: || (GET_RTX_CLASS (code) == 'i'
342: && (prev_code == JUMP_INSN
343: || (prev_code == CALL_INSN
344: && nonlocal_label_list != 0
345: /* Ignore a CLOBBER after a CALL_INSN here. */
346: && ! (code == INSN
347: && GET_CODE (PATTERN (insn)) == CLOBBER))
348: || prev_code == BARRIER)))
349: i++;
350: if (code != NOTE
351: /* Skip a CLOBBER after a CALL_INSN. See similar code in
352: find_basic_blocks. */
353: && ! (prev_code == CALL_INSN
354: && code == INSN && GET_CODE (PATTERN (insn)) == CLOBBER))
355: prev_code = code;
356: }
357: }
358:
359: #ifdef AUTO_INC_DEC
360: /* Leave space for insns we make in some cases for auto-inc. These cases
361: are rare, so we don't need too much space. */
362: max_uid_for_flow += max_uid_for_flow / 10;
363: #endif
364:
365: /* Allocate some tables that last till end of compiling this function
366: and some needed only in find_basic_blocks and life_analysis. */
367:
368: n_basic_blocks = i;
369: basic_block_head = (rtx *) oballoc (n_basic_blocks * sizeof (rtx));
370: basic_block_end = (rtx *) oballoc (n_basic_blocks * sizeof (rtx));
371: basic_block_drops_in = (char *) alloca (n_basic_blocks);
372: basic_block_loop_depth = (short *) alloca (n_basic_blocks * sizeof (short));
373: uid_block_number
374: = (int *) alloca ((max_uid_for_flow + 1) * sizeof (int));
375: uid_volatile = (char *) alloca (max_uid_for_flow + 1);
376: bzero (uid_volatile, max_uid_for_flow + 1);
377:
378: find_basic_blocks (f, nonlocal_label_list);
379: life_analysis (f, nregs);
380: if (file)
381: dump_flow_info (file);
382:
383: basic_block_drops_in = 0;
384: uid_block_number = 0;
385: basic_block_loop_depth = 0;
386: }
387:
388: /* Find all basic blocks of the function whose first insn is F.
389: Store the correct data in the tables that describe the basic blocks,
390: set up the chains of references for each CODE_LABEL, and
391: delete any entire basic blocks that cannot be reached.
392:
393: NONLOCAL_LABEL_LIST is the same local variable from flow_analysis. */
394:
395: static void
396: find_basic_blocks (f, nonlocal_label_list)
397: rtx f, nonlocal_label_list;
398: {
399: register rtx insn;
400: register int i;
401: register char *block_live = (char *) alloca (n_basic_blocks);
402: register char *block_marked = (char *) alloca (n_basic_blocks);
403: /* List of label_refs to all labels whose addresses are taken
404: and used as data. */
405: rtx label_value_list = 0;
406:
407: block_live_static = block_live;
408: bzero (block_live, n_basic_blocks);
409: bzero (block_marked, n_basic_blocks);
410:
411: /* Initialize with just block 0 reachable and no blocks marked. */
412: if (n_basic_blocks > 0)
413: block_live[0] = 1;
414:
415: /* Initialize the ref chain of each label to 0. */
416: /* Record where all the blocks start and end and their depth in loops. */
417: /* For each insn, record the block it is in. */
418: /* Also mark as reachable any blocks headed by labels that
419: must not be deleted. */
420:
421: {
422: register RTX_CODE prev_code = JUMP_INSN;
423: register RTX_CODE code;
424: int depth = 1;
425:
426: for (insn = f, i = -1; insn; insn = NEXT_INSN (insn))
427: {
428: code = GET_CODE (insn);
429: if (code == NOTE)
430: {
431: if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG)
432: depth++;
433: else if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_END)
434: depth--;
435: }
436: /* A basic block starts at label, or after something that can jump. */
437: else if (code == CODE_LABEL
438: || (GET_RTX_CLASS (code) == 'i'
439: && (prev_code == JUMP_INSN
440: || (prev_code == CALL_INSN
441: && nonlocal_label_list != 0
442: /* Ignore if CLOBBER since we consider this
443: part of the CALL. See below. */
444: && ! (code == INSN
445: && GET_CODE (PATTERN (insn)) == CLOBBER))
446: || prev_code == BARRIER)))
447: {
448: basic_block_head[++i] = insn;
449: basic_block_end[i] = insn;
450: basic_block_loop_depth[i] = depth;
451: if (code == CODE_LABEL)
452: {
453: LABEL_REFS (insn) = insn;
454: /* Any label that cannot be deleted
455: is considered to start a reachable block. */
456: if (LABEL_PRESERVE_P (insn))
457: block_live[i] = 1;
458: }
459: }
460: else if (GET_RTX_CLASS (code) == 'i')
461: {
462: basic_block_end[i] = insn;
463: basic_block_loop_depth[i] = depth;
464: }
465:
466: /* Make a list of all labels referred to other than by jumps. */
467: if (code == INSN || code == CALL_INSN)
468: {
469: rtx note = find_reg_note (insn, REG_LABEL, NULL_RTX);
470: if (note != 0)
471: label_value_list = gen_rtx (EXPR_LIST, VOIDmode, XEXP (note, 0),
472: label_value_list);
473: }
474:
475: BLOCK_NUM (insn) = i;
476:
477: /* Don't separate a CALL_INSN from following CLOBBER insns. This is
478: a kludge that will go away when each CALL_INSN records its
479: USE and CLOBBERs. */
480:
481: if (code != NOTE
482: && ! (prev_code == CALL_INSN && code == INSN
483: && GET_CODE (PATTERN (insn)) == CLOBBER))
484: prev_code = code;
485: }
486: if (i + 1 != n_basic_blocks)
487: abort ();
488: }
489:
490: /* Don't delete the labels (in this function)
491: that are referenced by non-jump instructions. */
492: {
493: register rtx x;
494: for (x = label_value_list; x; x = XEXP (x, 1))
495: if (! LABEL_REF_NONLOCAL_P (x))
496: block_live[BLOCK_NUM (XEXP (x, 0))] = 1;
497: }
498:
499: /* Record which basic blocks control can drop in to. */
500:
501: {
502: register int i;
503: for (i = 0; i < n_basic_blocks; i++)
504: {
505: register rtx insn = PREV_INSN (basic_block_head[i]);
506: /* TEMP1 is used to avoid a bug in Sequent's compiler. */
507: register int temp1;
508: while (insn && GET_CODE (insn) == NOTE)
509: insn = PREV_INSN (insn);
510: temp1 = insn && GET_CODE (insn) != BARRIER;
511: basic_block_drops_in[i] = temp1;
512: }
513: }
514:
515: /* Now find which basic blocks can actually be reached
516: and put all jump insns' LABEL_REFS onto the ref-chains
517: of their target labels. */
518:
519: if (n_basic_blocks > 0)
520: {
521: int something_marked = 1;
522:
523: /* Find all indirect jump insns and mark them as possibly jumping
524: to all the labels whose addresses are explicitly used.
525: This is because, when there are computed gotos,
526: we can't tell which labels they jump to, of all the possibilities. */
527:
528: for (insn = f; insn; insn = NEXT_INSN (insn))
529: if (GET_CODE (insn) == JUMP_INSN
530: && GET_CODE (PATTERN (insn)) == SET
531: && SET_DEST (PATTERN (insn)) == pc_rtx
532: && (GET_CODE (SET_SRC (PATTERN (insn))) == REG
533: || GET_CODE (SET_SRC (PATTERN (insn))) == MEM))
534: {
535: rtx x;
536: for (x = label_value_list; x; x = XEXP (x, 1))
537: mark_label_ref (gen_rtx (LABEL_REF, VOIDmode, XEXP (x, 0)),
538: insn, 0);
539: for (x = forced_labels; x; x = XEXP (x, 1))
540: mark_label_ref (gen_rtx (LABEL_REF, VOIDmode, XEXP (x, 0)),
541: insn, 0);
542: }
543:
544: /* Find all call insns and mark them as possibly jumping
545: to all the nonlocal goto handler labels. */
546:
547: for (insn = f; insn; insn = NEXT_INSN (insn))
548: if (GET_CODE (insn) == CALL_INSN)
549: {
550: rtx x;
551: for (x = nonlocal_label_list; x; x = XEXP (x, 1))
552: /* Don't try marking labels that
553: were deleted as unreferenced. */
554: if (GET_CODE (XEXP (x, 0)) == CODE_LABEL)
555: mark_label_ref (gen_rtx (LABEL_REF, VOIDmode, XEXP (x, 0)),
556: insn, 0);
557: /* ??? This could be made smarter:
558: in some cases it's possible to tell that certain
559: calls will not do a nonlocal goto.
560:
561: For example, if the nested functions that do the
562: nonlocal gotos do not have their addresses taken, then
563: only calls to those functions or to other nested
564: functions that use them could possibly do nonlocal
565: gotos. */
566: }
567:
568: /* Pass over all blocks, marking each block that is reachable
569: and has not yet been marked.
570: Keep doing this until, in one pass, no blocks have been marked.
571: Then blocks_live and blocks_marked are identical and correct.
572: In addition, all jumps actually reachable have been marked. */
573:
574: while (something_marked)
575: {
576: something_marked = 0;
577: for (i = 0; i < n_basic_blocks; i++)
578: if (block_live[i] && !block_marked[i])
579: {
580: block_marked[i] = 1;
581: something_marked = 1;
582: if (i + 1 < n_basic_blocks && basic_block_drops_in[i + 1])
583: block_live[i + 1] = 1;
584: insn = basic_block_end[i];
585: if (GET_CODE (insn) == JUMP_INSN)
586: mark_label_ref (PATTERN (insn), insn, 0);
587: }
588: }
589:
590: /* Now delete the code for any basic blocks that can't be reached.
591: They can occur because jump_optimize does not recognize
592: unreachable loops as unreachable. */
593:
594: for (i = 0; i < n_basic_blocks; i++)
595: if (!block_live[i])
596: {
597: insn = basic_block_head[i];
598: while (1)
599: {
600: if (GET_CODE (insn) == BARRIER)
601: abort ();
602: if (GET_CODE (insn) != NOTE)
603: {
604: PUT_CODE (insn, NOTE);
605: NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED;
606: NOTE_SOURCE_FILE (insn) = 0;
607: }
608: if (insn == basic_block_end[i])
609: {
610: /* BARRIERs are between basic blocks, not part of one.
611: Delete a BARRIER if the preceding jump is deleted.
612: We cannot alter a BARRIER into a NOTE
613: because it is too short; but we can really delete
614: it because it is not part of a basic block. */
615: if (NEXT_INSN (insn) != 0
616: && GET_CODE (NEXT_INSN (insn)) == BARRIER)
617: delete_insn (NEXT_INSN (insn));
618: break;
619: }
620: insn = NEXT_INSN (insn);
621: }
622: /* Each time we delete some basic blocks,
623: see if there is a jump around them that is
624: being turned into a no-op. If so, delete it. */
625:
626: if (block_live[i - 1])
627: {
628: register int j;
629: for (j = i; j < n_basic_blocks; j++)
630: if (block_live[j])
631: {
632: rtx label;
633: insn = basic_block_end[i - 1];
634: if (GET_CODE (insn) == JUMP_INSN
635: /* An unconditional jump is the only possibility
636: we must check for, since a conditional one
637: would make these blocks live. */
638: && simplejump_p (insn)
639: && (label = XEXP (SET_SRC (PATTERN (insn)), 0), 1)
640: && INSN_UID (label) != 0
641: && BLOCK_NUM (label) == j)
642: {
643: PUT_CODE (insn, NOTE);
644: NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED;
645: NOTE_SOURCE_FILE (insn) = 0;
646: if (GET_CODE (NEXT_INSN (insn)) != BARRIER)
647: abort ();
648: delete_insn (NEXT_INSN (insn));
649: }
650: break;
651: }
652: }
653: }
654: }
655: }
656:
657: /* Check expression X for label references;
658: if one is found, add INSN to the label's chain of references.
659:
660: CHECKDUP means check for and avoid creating duplicate references
661: from the same insn. Such duplicates do no serious harm but
662: can slow life analysis. CHECKDUP is set only when duplicates
663: are likely. */
664:
665: static void
666: mark_label_ref (x, insn, checkdup)
667: rtx x, insn;
668: int checkdup;
669: {
670: register RTX_CODE code;
671: register int i;
672: register char *fmt;
673:
674: /* We can be called with NULL when scanning label_value_list. */
675: if (x == 0)
676: return;
677:
678: code = GET_CODE (x);
679: if (code == LABEL_REF)
680: {
681: register rtx label = XEXP (x, 0);
682: register rtx y;
683: if (GET_CODE (label) != CODE_LABEL)
684: abort ();
685: /* If the label was never emitted, this insn is junk,
686: but avoid a crash trying to refer to BLOCK_NUM (label).
687: This can happen as a result of a syntax error
688: and a diagnostic has already been printed. */
689: if (INSN_UID (label) == 0)
690: return;
691: CONTAINING_INSN (x) = insn;
692: /* if CHECKDUP is set, check for duplicate ref from same insn
693: and don't insert. */
694: if (checkdup)
695: for (y = LABEL_REFS (label); y != label; y = LABEL_NEXTREF (y))
696: if (CONTAINING_INSN (y) == insn)
697: return;
698: LABEL_NEXTREF (x) = LABEL_REFS (label);
699: LABEL_REFS (label) = x;
700: block_live_static[BLOCK_NUM (label)] = 1;
701: return;
702: }
703:
704: fmt = GET_RTX_FORMAT (code);
705: for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
706: {
707: if (fmt[i] == 'e')
708: mark_label_ref (XEXP (x, i), insn, 0);
709: if (fmt[i] == 'E')
710: {
711: register int j;
712: for (j = 0; j < XVECLEN (x, i); j++)
713: mark_label_ref (XVECEXP (x, i, j), insn, 1);
714: }
715: }
716: }
717:
718: /* Determine which registers are live at the start of each
719: basic block of the function whose first insn is F.
720: NREGS is the number of registers used in F.
721: We allocate the vector basic_block_live_at_start
722: and the regsets that it points to, and fill them with the data.
723: regset_size and regset_bytes are also set here. */
724:
725: static void
726: life_analysis (f, nregs)
727: rtx f;
728: int nregs;
729: {
730: register regset tem;
731: int first_pass;
732: int changed;
733: /* For each basic block, a bitmask of regs
734: live on exit from the block. */
735: regset *basic_block_live_at_end;
736: /* For each basic block, a bitmask of regs
737: live on entry to a successor-block of this block.
738: If this does not match basic_block_live_at_end,
739: that must be updated, and the block must be rescanned. */
740: regset *basic_block_new_live_at_end;
741: /* For each basic block, a bitmask of regs
742: whose liveness at the end of the basic block
743: can make a difference in which regs are live on entry to the block.
744: These are the regs that are set within the basic block,
745: possibly excluding those that are used after they are set. */
746: regset *basic_block_significant;
747: register int i;
748: rtx insn;
749:
750: struct obstack flow_obstack;
751:
752: gcc_obstack_init (&flow_obstack);
753:
754: max_regno = nregs;
755:
756: bzero (regs_ever_live, sizeof regs_ever_live);
757:
758: /* Allocate and zero out many data structures
759: that will record the data from lifetime analysis. */
760:
761: allocate_for_life_analysis ();
762:
763: reg_next_use = (rtx *) alloca (nregs * sizeof (rtx));
764: bzero (reg_next_use, nregs * sizeof (rtx));
765:
766: /* Set up several regset-vectors used internally within this function.
767: Their meanings are documented above, with their declarations. */
768:
769: basic_block_live_at_end = (regset *) alloca (n_basic_blocks * sizeof (regset));
770: /* Don't use alloca since that leads to a crash rather than an error message
771: if there isn't enough space.
772: Don't use oballoc since we may need to allocate other things during
773: this function on the temporary obstack. */
774: tem = (regset) obstack_alloc (&flow_obstack, n_basic_blocks * regset_bytes);
775: bzero (tem, n_basic_blocks * regset_bytes);
776: init_regset_vector (basic_block_live_at_end, tem, n_basic_blocks, regset_bytes);
777:
778: basic_block_new_live_at_end = (regset *) alloca (n_basic_blocks * sizeof (regset));
779: tem = (regset) obstack_alloc (&flow_obstack, n_basic_blocks * regset_bytes);
780: bzero (tem, n_basic_blocks * regset_bytes);
781: init_regset_vector (basic_block_new_live_at_end, tem, n_basic_blocks, regset_bytes);
782:
783: basic_block_significant = (regset *) alloca (n_basic_blocks * sizeof (regset));
784: tem = (regset) obstack_alloc (&flow_obstack, n_basic_blocks * regset_bytes);
785: bzero (tem, n_basic_blocks * regset_bytes);
786: init_regset_vector (basic_block_significant, tem, n_basic_blocks, regset_bytes);
787:
788: /* Record which insns refer to any volatile memory
789: or for any reason can't be deleted just because they are dead stores.
790: Also, delete any insns that copy a register to itself. */
791:
792: for (insn = f; insn; insn = NEXT_INSN (insn))
793: {
794: enum rtx_code code1 = GET_CODE (insn);
795: if (code1 == CALL_INSN)
796: INSN_VOLATILE (insn) = 1;
797: else if (code1 == INSN || code1 == JUMP_INSN)
798: {
799: /* Delete (in effect) any obvious no-op moves. */
800: if (GET_CODE (PATTERN (insn)) == SET
801: && GET_CODE (SET_DEST (PATTERN (insn))) == REG
802: && GET_CODE (SET_SRC (PATTERN (insn))) == REG
803: && REGNO (SET_DEST (PATTERN (insn))) ==
804: REGNO (SET_SRC (PATTERN (insn)))
805: /* Insns carrying these notes are useful later on. */
806: && ! find_reg_note (insn, REG_EQUAL, NULL_RTX))
807: {
808: PUT_CODE (insn, NOTE);
809: NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED;
810: NOTE_SOURCE_FILE (insn) = 0;
811: }
812: else if (GET_CODE (PATTERN (insn)) == PARALLEL)
813: {
814: /* If nothing but SETs of registers to themselves,
815: this insn can also be deleted. */
816: for (i = 0; i < XVECLEN (PATTERN (insn), 0); i++)
817: {
818: rtx tem = XVECEXP (PATTERN (insn), 0, i);
819:
820: if (GET_CODE (tem) == USE
821: || GET_CODE (tem) == CLOBBER)
822: continue;
823:
824: if (GET_CODE (tem) != SET
825: || GET_CODE (SET_DEST (tem)) != REG
826: || GET_CODE (SET_SRC (tem)) != REG
827: || REGNO (SET_DEST (tem)) != REGNO (SET_SRC (tem)))
828: break;
829: }
830:
831: if (i == XVECLEN (PATTERN (insn), 0)
832: /* Insns carrying these notes are useful later on. */
833: && ! find_reg_note (insn, REG_EQUAL, NULL_RTX))
834: {
835: PUT_CODE (insn, NOTE);
836: NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED;
837: NOTE_SOURCE_FILE (insn) = 0;
838: }
839: else
840: INSN_VOLATILE (insn) = volatile_refs_p (PATTERN (insn));
841: }
842: else if (GET_CODE (PATTERN (insn)) != USE)
843: INSN_VOLATILE (insn) = volatile_refs_p (PATTERN (insn));
844: /* A SET that makes space on the stack cannot be dead.
845: (Such SETs occur only for allocating variable-size data,
846: so they will always have a PLUS or MINUS according to the
847: direction of stack growth.)
848: Even if this function never uses this stack pointer value,
849: signal handlers do! */
850: else if (code1 == INSN && GET_CODE (PATTERN (insn)) == SET
851: && SET_DEST (PATTERN (insn)) == stack_pointer_rtx
852: #ifdef STACK_GROWS_DOWNWARD
853: && GET_CODE (SET_SRC (PATTERN (insn))) == MINUS
854: #else
855: && GET_CODE (SET_SRC (PATTERN (insn))) == PLUS
856: #endif
857: && XEXP (SET_SRC (PATTERN (insn)), 0) == stack_pointer_rtx)
858: INSN_VOLATILE (insn) = 1;
859: }
860: }
861:
862: if (n_basic_blocks > 0)
863: #ifdef EXIT_IGNORE_STACK
864: if (! EXIT_IGNORE_STACK
865: || (! FRAME_POINTER_REQUIRED && flag_omit_frame_pointer))
866: #endif
867: {
868: /* If exiting needs the right stack value,
869: consider the stack pointer live at the end of the function. */
870: basic_block_live_at_end[n_basic_blocks - 1]
871: [STACK_POINTER_REGNUM / REGSET_ELT_BITS]
872: |= (REGSET_ELT_TYPE) 1 << (STACK_POINTER_REGNUM % REGSET_ELT_BITS);
873: basic_block_new_live_at_end[n_basic_blocks - 1]
874: [STACK_POINTER_REGNUM / REGSET_ELT_BITS]
875: |= (REGSET_ELT_TYPE) 1 << (STACK_POINTER_REGNUM % REGSET_ELT_BITS);
876: }
877:
878: /* Mark the frame pointer is needed at the end of the function. If
879: we end up eliminating it, it will be removed from the live list
880: of each basic block by reload. */
881:
882: if (n_basic_blocks > 0)
883: {
884: basic_block_live_at_end[n_basic_blocks - 1]
885: [FRAME_POINTER_REGNUM / REGSET_ELT_BITS]
886: |= (REGSET_ELT_TYPE) 1 << (FRAME_POINTER_REGNUM % REGSET_ELT_BITS);
887: basic_block_new_live_at_end[n_basic_blocks - 1]
888: [FRAME_POINTER_REGNUM / REGSET_ELT_BITS]
889: |= (REGSET_ELT_TYPE) 1 << (FRAME_POINTER_REGNUM % REGSET_ELT_BITS);
890: #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
891: /* If they are different, also mark the hard frame pointer as live */
892: basic_block_live_at_end[n_basic_blocks - 1]
893: [HARD_FRAME_POINTER_REGNUM / REGSET_ELT_BITS]
894: |= (REGSET_ELT_TYPE) 1 << (HARD_FRAME_POINTER_REGNUM
895: % REGSET_ELT_BITS);
896: basic_block_new_live_at_end[n_basic_blocks - 1]
897: [HARD_FRAME_POINTER_REGNUM / REGSET_ELT_BITS]
898: |= (REGSET_ELT_TYPE) 1 << (HARD_FRAME_POINTER_REGNUM
899: % REGSET_ELT_BITS);
900: #endif
901: }
902:
903: /* Mark all global registers as being live at the end of the function
904: since they may be referenced by our caller. */
905:
906: if (n_basic_blocks > 0)
907: for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
908: if (global_regs[i])
909: {
910: basic_block_live_at_end[n_basic_blocks - 1]
911: [i / REGSET_ELT_BITS]
912: |= (REGSET_ELT_TYPE) 1 << (i % REGSET_ELT_BITS);
913: basic_block_new_live_at_end[n_basic_blocks - 1]
914: [i / REGSET_ELT_BITS]
915: |= (REGSET_ELT_TYPE) 1 << (i % REGSET_ELT_BITS);
916: }
917:
918: /* Propagate life info through the basic blocks
919: around the graph of basic blocks.
920:
921: This is a relaxation process: each time a new register
922: is live at the end of the basic block, we must scan the block
923: to determine which registers are, as a consequence, live at the beginning
924: of that block. These registers must then be marked live at the ends
925: of all the blocks that can transfer control to that block.
926: The process continues until it reaches a fixed point. */
927:
928: first_pass = 1;
929: changed = 1;
930: while (changed)
931: {
932: changed = 0;
933: for (i = n_basic_blocks - 1; i >= 0; i--)
934: {
935: int consider = first_pass;
936: int must_rescan = first_pass;
937: register int j;
938:
939: if (!first_pass)
940: {
941: /* Set CONSIDER if this block needs thinking about at all
942: (that is, if the regs live now at the end of it
943: are not the same as were live at the end of it when
944: we last thought about it).
945: Set must_rescan if it needs to be thought about
946: instruction by instruction (that is, if any additional
947: reg that is live at the end now but was not live there before
948: is one of the significant regs of this basic block). */
949:
950: for (j = 0; j < regset_size; j++)
951: {
952: register REGSET_ELT_TYPE x
953: = (basic_block_new_live_at_end[i][j]
954: & ~basic_block_live_at_end[i][j]);
955: if (x)
956: consider = 1;
957: if (x & basic_block_significant[i][j])
958: {
959: must_rescan = 1;
960: consider = 1;
961: break;
962: }
963: }
964:
965: if (! consider)
966: continue;
967: }
968:
969: /* The live_at_start of this block may be changing,
970: so another pass will be required after this one. */
971: changed = 1;
972:
973: if (! must_rescan)
974: {
975: /* No complete rescan needed;
976: just record those variables newly known live at end
977: as live at start as well. */
978: for (j = 0; j < regset_size; j++)
979: {
980: register REGSET_ELT_TYPE x
981: = (basic_block_new_live_at_end[i][j]
982: & ~basic_block_live_at_end[i][j]);
983: basic_block_live_at_start[i][j] |= x;
984: basic_block_live_at_end[i][j] |= x;
985: }
986: }
987: else
988: {
989: /* Update the basic_block_live_at_start
990: by propagation backwards through the block. */
991: bcopy (basic_block_new_live_at_end[i],
992: basic_block_live_at_end[i], regset_bytes);
993: bcopy (basic_block_live_at_end[i],
994: basic_block_live_at_start[i], regset_bytes);
995: propagate_block (basic_block_live_at_start[i],
996: basic_block_head[i], basic_block_end[i], 0,
997: first_pass ? basic_block_significant[i]
998: : (regset) 0,
999: i);
1000: }
1001:
1002: {
1003: register rtx jump, head;
1004: /* Update the basic_block_new_live_at_end's of the block
1005: that falls through into this one (if any). */
1006: head = basic_block_head[i];
1007: jump = PREV_INSN (head);
1008: if (basic_block_drops_in[i])
1009: {
1010: register int from_block = BLOCK_NUM (jump);
1011: register int j;
1012: for (j = 0; j < regset_size; j++)
1013: basic_block_new_live_at_end[from_block][j]
1014: |= basic_block_live_at_start[i][j];
1015: }
1016: /* Update the basic_block_new_live_at_end's of
1017: all the blocks that jump to this one. */
1018: if (GET_CODE (head) == CODE_LABEL)
1019: for (jump = LABEL_REFS (head);
1020: jump != head;
1021: jump = LABEL_NEXTREF (jump))
1022: {
1023: register int from_block = BLOCK_NUM (CONTAINING_INSN (jump));
1024: register int j;
1025: for (j = 0; j < regset_size; j++)
1026: basic_block_new_live_at_end[from_block][j]
1027: |= basic_block_live_at_start[i][j];
1028: }
1029: }
1030: #ifdef USE_C_ALLOCA
1031: alloca (0);
1032: #endif
1033: }
1034: first_pass = 0;
1035: }
1036:
1037: /* The only pseudos that are live at the beginning of the function are
1038: those that were not set anywhere in the function. local-alloc doesn't
1039: know how to handle these correctly, so mark them as not local to any
1040: one basic block. */
1041:
1042: if (n_basic_blocks > 0)
1043: for (i = FIRST_PSEUDO_REGISTER; i < max_regno; i++)
1044: if (basic_block_live_at_start[0][i / REGSET_ELT_BITS]
1045: & ((REGSET_ELT_TYPE) 1 << (i % REGSET_ELT_BITS)))
1046: reg_basic_block[i] = REG_BLOCK_GLOBAL;
1047:
1048: /* Now the life information is accurate.
1049: Make one more pass over each basic block
1050: to delete dead stores, create autoincrement addressing
1051: and record how many times each register is used, is set, or dies.
1052:
1053: To save time, we operate directly in basic_block_live_at_end[i],
1054: thus destroying it (in fact, converting it into a copy of
1055: basic_block_live_at_start[i]). This is ok now because
1056: basic_block_live_at_end[i] is no longer used past this point. */
1057:
1058: max_scratch = 0;
1059:
1060: for (i = 0; i < n_basic_blocks; i++)
1061: {
1062: propagate_block (basic_block_live_at_end[i],
1063: basic_block_head[i], basic_block_end[i], 1,
1064: (regset) 0, i);
1065: #ifdef USE_C_ALLOCA
1066: alloca (0);
1067: #endif
1068: }
1069:
1070: #if 0
1071: /* Something live during a setjmp should not be put in a register
1072: on certain machines which restore regs from stack frames
1073: rather than from the jmpbuf.
1074: But we don't need to do this for the user's variables, since
1075: ANSI says only volatile variables need this. */
1076: #ifdef LONGJMP_RESTORE_FROM_STACK
1077: for (i = FIRST_PSEUDO_REGISTER; i < nregs; i++)
1078: if (regs_live_at_setjmp[i / REGSET_ELT_BITS]
1079: & ((REGSET_ELT_TYPE) 1 << (i % REGSET_ELT_BITS))
1080: && regno_reg_rtx[i] != 0 && ! REG_USERVAR_P (regno_reg_rtx[i]))
1081: {
1082: reg_live_length[i] = -1;
1083: reg_basic_block[i] = -1;
1084: }
1085: #endif
1086: #endif
1087:
1088: /* We have a problem with any pseudoreg that
1089: lives across the setjmp. ANSI says that if a
1090: user variable does not change in value
1091: between the setjmp and the longjmp, then the longjmp preserves it.
1092: This includes longjmp from a place where the pseudo appears dead.
1093: (In principle, the value still exists if it is in scope.)
1094: If the pseudo goes in a hard reg, some other value may occupy
1095: that hard reg where this pseudo is dead, thus clobbering the pseudo.
1096: Conclusion: such a pseudo must not go in a hard reg. */
1097: for (i = FIRST_PSEUDO_REGISTER; i < nregs; i++)
1098: if ((regs_live_at_setjmp[i / REGSET_ELT_BITS]
1099: & ((REGSET_ELT_TYPE) 1 << (i % REGSET_ELT_BITS)))
1100: && regno_reg_rtx[i] != 0)
1101: {
1102: reg_live_length[i] = -1;
1103: reg_basic_block[i] = -1;
1104: }
1105:
1106: obstack_free (&flow_obstack, NULL_PTR);
1107: }
1108:
1109: /* Subroutines of life analysis. */
1110:
1111: /* Allocate the permanent data structures that represent the results
1112: of life analysis. Not static since used also for stupid life analysis. */
1113:
1114: void
1115: allocate_for_life_analysis ()
1116: {
1117: register int i;
1118: register regset tem;
1119:
1120: regset_size = ((max_regno + REGSET_ELT_BITS - 1) / REGSET_ELT_BITS);
1121: regset_bytes = regset_size * sizeof (*(regset)0);
1122:
1123: reg_n_refs = (int *) oballoc (max_regno * sizeof (int));
1124: bzero (reg_n_refs, max_regno * sizeof (int));
1125:
1126: reg_n_sets = (short *) oballoc (max_regno * sizeof (short));
1127: bzero (reg_n_sets, max_regno * sizeof (short));
1128:
1129: reg_n_deaths = (short *) oballoc (max_regno * sizeof (short));
1130: bzero (reg_n_deaths, max_regno * sizeof (short));
1131:
1132: reg_live_length = (int *) oballoc (max_regno * sizeof (int));
1133: bzero (reg_live_length, max_regno * sizeof (int));
1134:
1135: reg_n_calls_crossed = (int *) oballoc (max_regno * sizeof (int));
1136: bzero (reg_n_calls_crossed, max_regno * sizeof (int));
1137:
1138: reg_basic_block = (int *) oballoc (max_regno * sizeof (int));
1139: for (i = 0; i < max_regno; i++)
1140: reg_basic_block[i] = REG_BLOCK_UNKNOWN;
1141:
1142: basic_block_live_at_start = (regset *) oballoc (n_basic_blocks * sizeof (regset));
1143: tem = (regset) oballoc (n_basic_blocks * regset_bytes);
1144: bzero (tem, n_basic_blocks * regset_bytes);
1145: init_regset_vector (basic_block_live_at_start, tem, n_basic_blocks, regset_bytes);
1146:
1147: regs_live_at_setjmp = (regset) oballoc (regset_bytes);
1148: bzero (regs_live_at_setjmp, regset_bytes);
1149: }
1150:
1151: /* Make each element of VECTOR point at a regset,
1152: taking the space for all those regsets from SPACE.
1153: SPACE is of type regset, but it is really as long as NELTS regsets.
1154: BYTES_PER_ELT is the number of bytes in one regset. */
1155:
1156: static void
1157: init_regset_vector (vector, space, nelts, bytes_per_elt)
1158: regset *vector;
1159: regset space;
1160: int nelts;
1161: int bytes_per_elt;
1162: {
1163: register int i;
1164: register regset p = space;
1165:
1166: for (i = 0; i < nelts; i++)
1167: {
1168: vector[i] = p;
1169: p += bytes_per_elt / sizeof (*p);
1170: }
1171: }
1172:
1173: /* Compute the registers live at the beginning of a basic block
1174: from those live at the end.
1175:
1176: When called, OLD contains those live at the end.
1177: On return, it contains those live at the beginning.
1178: FIRST and LAST are the first and last insns of the basic block.
1179:
1180: FINAL is nonzero if we are doing the final pass which is not
1181: for computing the life info (since that has already been done)
1182: but for acting on it. On this pass, we delete dead stores,
1183: set up the logical links and dead-variables lists of instructions,
1184: and merge instructions for autoincrement and autodecrement addresses.
1185:
1186: SIGNIFICANT is nonzero only the first time for each basic block.
1187: If it is nonzero, it points to a regset in which we store
1188: a 1 for each register that is set within the block.
1189:
1190: BNUM is the number of the basic block. */
1191:
1192: static void
1193: propagate_block (old, first, last, final, significant, bnum)
1194: register regset old;
1195: rtx first;
1196: rtx last;
1197: int final;
1198: regset significant;
1199: int bnum;
1200: {
1201: register rtx insn;
1202: rtx prev;
1203: regset live;
1204: regset dead;
1205:
1206: /* The following variables are used only if FINAL is nonzero. */
1207: /* This vector gets one element for each reg that has been live
1208: at any point in the basic block that has been scanned so far.
1209: SOMETIMES_MAX says how many elements are in use so far.
1210: In each element, OFFSET is the byte-number within a regset
1211: for the register described by the element, and BIT is a mask
1212: for that register's bit within the byte. */
1213: register struct sometimes { short offset; short bit; } *regs_sometimes_live;
1214: int sometimes_max = 0;
1215: /* This regset has 1 for each reg that we have seen live so far.
1216: It and REGS_SOMETIMES_LIVE are updated together. */
1217: regset maxlive;
1218:
1219: /* The loop depth may change in the middle of a basic block. Since we
1220: scan from end to beginning, we start with the depth at the end of the
1221: current basic block, and adjust as we pass ends and starts of loops. */
1222: loop_depth = basic_block_loop_depth[bnum];
1223:
1224: dead = (regset) alloca (regset_bytes);
1225: live = (regset) alloca (regset_bytes);
1226:
1227: cc0_live = 0;
1228: last_mem_set = 0;
1229:
1230: /* Include any notes at the end of the block in the scan.
1231: This is in case the block ends with a call to setjmp. */
1232:
1233: while (NEXT_INSN (last) != 0 && GET_CODE (NEXT_INSN (last)) == NOTE)
1234: {
1235: /* Look for loop boundaries, we are going forward here. */
1236: last = NEXT_INSN (last);
1237: if (NOTE_LINE_NUMBER (last) == NOTE_INSN_LOOP_BEG)
1238: loop_depth++;
1239: else if (NOTE_LINE_NUMBER (last) == NOTE_INSN_LOOP_END)
1240: loop_depth--;
1241: }
1242:
1243: if (final)
1244: {
1245: register int i, offset;
1246: REGSET_ELT_TYPE bit;
1247:
1248: num_scratch = 0;
1249: maxlive = (regset) alloca (regset_bytes);
1250: bcopy (old, maxlive, regset_bytes);
1251: regs_sometimes_live
1252: = (struct sometimes *) alloca (max_regno * sizeof (struct sometimes));
1253:
1254: /* Process the regs live at the end of the block.
1255: Enter them in MAXLIVE and REGS_SOMETIMES_LIVE.
1256: Also mark them as not local to any one basic block. */
1257:
1258: for (offset = 0, i = 0; offset < regset_size; offset++)
1259: for (bit = 1; bit; bit <<= 1, i++)
1260: {
1261: if (i == max_regno)
1262: break;
1263: if (old[offset] & bit)
1264: {
1265: reg_basic_block[i] = REG_BLOCK_GLOBAL;
1266: regs_sometimes_live[sometimes_max].offset = offset;
1267: regs_sometimes_live[sometimes_max].bit = i % REGSET_ELT_BITS;
1268: sometimes_max++;
1269: }
1270: }
1271: }
1272:
1273: /* Scan the block an insn at a time from end to beginning. */
1274:
1275: for (insn = last; ; insn = prev)
1276: {
1277: prev = PREV_INSN (insn);
1278:
1279: /* Look for loop boundaries, remembering that we are going backwards. */
1280: if (GET_CODE (insn) == NOTE
1281: && NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_END)
1282: loop_depth++;
1283: else if (GET_CODE (insn) == NOTE
1284: && NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG)
1285: loop_depth--;
1286:
1287: /* If we have LOOP_DEPTH == 0, there has been a bookkeeping error.
1288: Abort now rather than setting register status incorrectly. */
1289: if (loop_depth == 0)
1290: abort ();
1291:
1292: /* If this is a call to `setjmp' et al,
1293: warn if any non-volatile datum is live. */
1294:
1295: if (final && GET_CODE (insn) == NOTE
1296: && NOTE_LINE_NUMBER (insn) == NOTE_INSN_SETJMP)
1297: {
1298: int i;
1299: for (i = 0; i < regset_size; i++)
1300: regs_live_at_setjmp[i] |= old[i];
1301: }
1302:
1303: /* Update the life-status of regs for this insn.
1304: First DEAD gets which regs are set in this insn
1305: then LIVE gets which regs are used in this insn.
1306: Then the regs live before the insn
1307: are those live after, with DEAD regs turned off,
1308: and then LIVE regs turned on. */
1309:
1310: if (GET_RTX_CLASS (GET_CODE (insn)) == 'i')
1311: {
1312: register int i;
1313: rtx note = find_reg_note (insn, REG_RETVAL, NULL_RTX);
1314: int insn_is_dead
1315: = (insn_dead_p (PATTERN (insn), old, 0)
1316: /* Don't delete something that refers to volatile storage! */
1317: && ! INSN_VOLATILE (insn));
1318: int libcall_is_dead
1319: = (insn_is_dead && note != 0
1320: && libcall_dead_p (PATTERN (insn), old, note, insn));
1321:
1322: /* If an instruction consists of just dead store(s) on final pass,
1323: "delete" it by turning it into a NOTE of type NOTE_INSN_DELETED.
1324: We could really delete it with delete_insn, but that
1325: can cause trouble for first or last insn in a basic block. */
1326: if (final && insn_is_dead)
1327: {
1328: PUT_CODE (insn, NOTE);
1329: NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED;
1330: NOTE_SOURCE_FILE (insn) = 0;
1331:
1332: /* CC0 is now known to be dead. Either this insn used it,
1333: in which case it doesn't anymore, or clobbered it,
1334: so the next insn can't use it. */
1335: cc0_live = 0;
1336:
1337: /* If this insn is copying the return value from a library call,
1338: delete the entire library call. */
1339: if (libcall_is_dead)
1340: {
1341: rtx first = XEXP (note, 0);
1342: rtx p = insn;
1343: while (INSN_DELETED_P (first))
1344: first = NEXT_INSN (first);
1345: while (p != first)
1346: {
1347: p = PREV_INSN (p);
1348: PUT_CODE (p, NOTE);
1349: NOTE_LINE_NUMBER (p) = NOTE_INSN_DELETED;
1350: NOTE_SOURCE_FILE (p) = 0;
1351: }
1352: }
1353: goto flushed;
1354: }
1355:
1356: for (i = 0; i < regset_size; i++)
1357: {
1358: dead[i] = 0; /* Faster than bzero here */
1359: live[i] = 0; /* since regset_size is usually small */
1360: }
1361:
1362: /* See if this is an increment or decrement that can be
1363: merged into a following memory address. */
1364: #ifdef AUTO_INC_DEC
1365: {
1366: register rtx x = PATTERN (insn);
1367: /* Does this instruction increment or decrement a register? */
1368: if (final && GET_CODE (x) == SET
1369: && GET_CODE (SET_DEST (x)) == REG
1370: && (GET_CODE (SET_SRC (x)) == PLUS
1371: || GET_CODE (SET_SRC (x)) == MINUS)
1372: && XEXP (SET_SRC (x), 0) == SET_DEST (x)
1373: && GET_CODE (XEXP (SET_SRC (x), 1)) == CONST_INT
1374: /* Ok, look for a following memory ref we can combine with.
1375: If one is found, change the memory ref to a PRE_INC
1376: or PRE_DEC, cancel this insn, and return 1.
1377: Return 0 if nothing has been done. */
1378: && try_pre_increment_1 (insn))
1379: goto flushed;
1380: }
1381: #endif /* AUTO_INC_DEC */
1382:
1383: /* If this is not the final pass, and this insn is copying the
1384: value of a library call and it's dead, don't scan the
1385: insns that perform the library call, so that the call's
1386: arguments are not marked live. */
1387: if (libcall_is_dead)
1388: {
1389: /* Mark the dest reg as `significant'. */
1390: mark_set_regs (old, dead, PATTERN (insn), NULL_RTX, significant);
1391:
1392: insn = XEXP (note, 0);
1393: prev = PREV_INSN (insn);
1394: }
1395: else if (GET_CODE (PATTERN (insn)) == SET
1396: && SET_DEST (PATTERN (insn)) == stack_pointer_rtx
1397: && GET_CODE (SET_SRC (PATTERN (insn))) == PLUS
1398: && XEXP (SET_SRC (PATTERN (insn)), 0) == stack_pointer_rtx
1399: && GET_CODE (XEXP (SET_SRC (PATTERN (insn)), 1)) == CONST_INT)
1400: /* We have an insn to pop a constant amount off the stack.
1401: (Such insns use PLUS regardless of the direction of the stack,
1402: and any insn to adjust the stack by a constant is always a pop.)
1403: These insns, if not dead stores, have no effect on life. */
1404: ;
1405: else
1406: {
1407: /* LIVE gets the regs used in INSN;
1408: DEAD gets those set by it. Dead insns don't make anything
1409: live. */
1410:
1411: mark_set_regs (old, dead, PATTERN (insn),
1412: final ? insn : NULL_RTX, significant);
1413:
1414: /* If an insn doesn't use CC0, it becomes dead since we
1415: assume that every insn clobbers it. So show it dead here;
1416: mark_used_regs will set it live if it is referenced. */
1417: cc0_live = 0;
1418:
1419: if (! insn_is_dead)
1420: mark_used_regs (old, live, PATTERN (insn), final, insn);
1421:
1422: /* Sometimes we may have inserted something before INSN (such as
1423: a move) when we make an auto-inc. So ensure we will scan
1424: those insns. */
1425: #ifdef AUTO_INC_DEC
1426: prev = PREV_INSN (insn);
1427: #endif
1428:
1429: if (! insn_is_dead && GET_CODE (insn) == CALL_INSN)
1430: {
1431: register int i;
1432:
1433: /* Each call clobbers all call-clobbered regs that are not
1434: global. Note that the function-value reg is a
1435: call-clobbered reg, and mark_set_regs has already had
1436: a chance to handle it. */
1437:
1438: for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
1439: if (call_used_regs[i] && ! global_regs[i])
1440: dead[i / REGSET_ELT_BITS]
1441: |= ((REGSET_ELT_TYPE) 1 << (i % REGSET_ELT_BITS));
1442:
1443: /* The stack ptr is used (honorarily) by a CALL insn. */
1444: live[STACK_POINTER_REGNUM / REGSET_ELT_BITS]
1445: |= ((REGSET_ELT_TYPE) 1
1446: << (STACK_POINTER_REGNUM % REGSET_ELT_BITS));
1447:
1448: /* Calls may also reference any of the global registers,
1449: so they are made live. */
1450:
1451: for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
1452: if (global_regs[i])
1453: live[i / REGSET_ELT_BITS]
1454: |= ((REGSET_ELT_TYPE) 1 << (i % REGSET_ELT_BITS));
1455:
1456: /* Calls also clobber memory. */
1457: last_mem_set = 0;
1458: }
1459:
1460: /* Update OLD for the registers used or set. */
1461: for (i = 0; i < regset_size; i++)
1462: {
1463: old[i] &= ~dead[i];
1464: old[i] |= live[i];
1465: }
1466:
1467: if (GET_CODE (insn) == CALL_INSN && final)
1468: {
1469: /* Any regs live at the time of a call instruction
1470: must not go in a register clobbered by calls.
1471: Find all regs now live and record this for them. */
1472:
1473: register struct sometimes *p = regs_sometimes_live;
1474:
1475: for (i = 0; i < sometimes_max; i++, p++)
1476: if (old[p->offset] & ((REGSET_ELT_TYPE) 1 << p->bit))
1477: reg_n_calls_crossed[p->offset * REGSET_ELT_BITS + p->bit]+= 1;
1478: }
1479: }
1480:
1481: /* On final pass, add any additional sometimes-live regs
1482: into MAXLIVE and REGS_SOMETIMES_LIVE.
1483: Also update counts of how many insns each reg is live at. */
1484:
1485: if (final)
1486: {
1487: for (i = 0; i < regset_size; i++)
1488: {
1489: register REGSET_ELT_TYPE diff = live[i] & ~maxlive[i];
1490:
1491: if (diff)
1492: {
1493: register int regno;
1494: maxlive[i] |= diff;
1495: for (regno = 0; diff && regno < REGSET_ELT_BITS; regno++)
1496: if (diff & ((REGSET_ELT_TYPE) 1 << regno))
1497: {
1498: regs_sometimes_live[sometimes_max].offset = i;
1499: regs_sometimes_live[sometimes_max].bit = regno;
1500: diff &= ~ ((REGSET_ELT_TYPE) 1 << regno);
1501: sometimes_max++;
1502: }
1503: }
1504: }
1505:
1506: {
1507: register struct sometimes *p = regs_sometimes_live;
1508: for (i = 0; i < sometimes_max; i++, p++)
1509: {
1510: if (old[p->offset] & ((REGSET_ELT_TYPE) 1 << p->bit))
1511: reg_live_length[p->offset * REGSET_ELT_BITS + p->bit]++;
1512: }
1513: }
1514: }
1515: }
1516: flushed: ;
1517: if (insn == first)
1518: break;
1519: }
1520:
1521: if (num_scratch > max_scratch)
1522: max_scratch = num_scratch;
1523: }
1524:
1525: /* Return 1 if X (the body of an insn, or part of it) is just dead stores
1526: (SET expressions whose destinations are registers dead after the insn).
1527: NEEDED is the regset that says which regs are alive after the insn.
1528:
1529: Unless CALL_OK is non-zero, an insn is needed if it contains a CALL. */
1530:
1531: static int
1532: insn_dead_p (x, needed, call_ok)
1533: rtx x;
1534: regset needed;
1535: int call_ok;
1536: {
1537: register RTX_CODE code = GET_CODE (x);
1538: /* If setting something that's a reg or part of one,
1539: see if that register's altered value will be live. */
1540:
1541: if (code == SET)
1542: {
1543: register rtx r = SET_DEST (x);
1544: /* A SET that is a subroutine call cannot be dead. */
1545: if (! call_ok && GET_CODE (SET_SRC (x)) == CALL)
1546: return 0;
1547:
1548: #ifdef HAVE_cc0
1549: if (GET_CODE (r) == CC0)
1550: return ! cc0_live;
1551: #endif
1552:
1553: if (GET_CODE (r) == MEM && last_mem_set && ! MEM_VOLATILE_P (r)
1554: && rtx_equal_p (r, last_mem_set))
1555: return 1;
1556:
1557: while (GET_CODE (r) == SUBREG
1558: || GET_CODE (r) == STRICT_LOW_PART
1559: || GET_CODE (r) == ZERO_EXTRACT
1560: || GET_CODE (r) == SIGN_EXTRACT)
1561: r = SUBREG_REG (r);
1562:
1563: if (GET_CODE (r) == REG)
1564: {
1565: register int regno = REGNO (r);
1566: register int offset = regno / REGSET_ELT_BITS;
1567: register REGSET_ELT_TYPE bit
1568: = (REGSET_ELT_TYPE) 1 << (regno % REGSET_ELT_BITS);
1569:
1570: /* Don't delete insns to set global regs. */
1571: if ((regno < FIRST_PSEUDO_REGISTER && global_regs[regno])
1572: /* Make sure insns to set frame pointer aren't deleted. */
1573: || regno == FRAME_POINTER_REGNUM
1574: #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
1575: || regno == HARD_FRAME_POINTER_REGNUM
1576: #endif
1577: #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
1578: /* Make sure insns to set arg pointer are never deleted
1579: (if the arg pointer isn't fixed, there will be a USE for
1580: it, so we can treat it normally). */
1581: || (regno == ARG_POINTER_REGNUM && fixed_regs[regno])
1582: #endif
1583: || (needed[offset] & bit) != 0)
1584: return 0;
1585:
1586: /* If this is a hard register, verify that subsequent words are
1587: not needed. */
1588: if (regno < FIRST_PSEUDO_REGISTER)
1589: {
1590: int n = HARD_REGNO_NREGS (regno, GET_MODE (r));
1591:
1592: while (--n > 0)
1593: if ((needed[(regno + n) / REGSET_ELT_BITS]
1594: & ((REGSET_ELT_TYPE) 1
1595: << ((regno + n) % REGSET_ELT_BITS))) != 0)
1596: return 0;
1597: }
1598:
1599: return 1;
1600: }
1601: }
1602: /* If performing several activities,
1603: insn is dead if each activity is individually dead.
1604: Also, CLOBBERs and USEs can be ignored; a CLOBBER or USE
1605: that's inside a PARALLEL doesn't make the insn worth keeping. */
1606: else if (code == PARALLEL)
1607: {
1608: register int i = XVECLEN (x, 0);
1609: for (i--; i >= 0; i--)
1610: {
1611: rtx elt = XVECEXP (x, 0, i);
1612: if (!insn_dead_p (elt, needed, call_ok)
1613: && GET_CODE (elt) != CLOBBER
1614: && GET_CODE (elt) != USE)
1615: return 0;
1616: }
1617: return 1;
1618: }
1619: /* We do not check CLOBBER or USE here.
1620: An insn consisting of just a CLOBBER or just a USE
1621: should not be deleted. */
1622: return 0;
1623: }
1624:
1625: /* If X is the pattern of the last insn in a libcall, and assuming X is dead,
1626: return 1 if the entire library call is dead.
1627: This is true if X copies a register (hard or pseudo)
1628: and if the hard return reg of the call insn is dead.
1629: (The caller should have tested the destination of X already for death.)
1630:
1631: If this insn doesn't just copy a register, then we don't
1632: have an ordinary libcall. In that case, cse could not have
1633: managed to substitute the source for the dest later on,
1634: so we can assume the libcall is dead.
1635:
1636: NEEDED is the bit vector of pseudoregs live before this insn.
1637: NOTE is the REG_RETVAL note of the insn. INSN is the insn itself. */
1638:
1639: static int
1640: libcall_dead_p (x, needed, note, insn)
1641: rtx x;
1642: regset needed;
1643: rtx note;
1644: rtx insn;
1645: {
1646: register RTX_CODE code = GET_CODE (x);
1647:
1648: if (code == SET)
1649: {
1650: register rtx r = SET_SRC (x);
1651: if (GET_CODE (r) == REG)
1652: {
1653: rtx call = XEXP (note, 0);
1654: register int i;
1655:
1656: /* Find the call insn. */
1657: while (call != insn && GET_CODE (call) != CALL_INSN)
1658: call = NEXT_INSN (call);
1659:
1660: /* If there is none, do nothing special,
1661: since ordinary death handling can understand these insns. */
1662: if (call == insn)
1663: return 0;
1664:
1665: /* See if the hard reg holding the value is dead.
1666: If this is a PARALLEL, find the call within it. */
1667: call = PATTERN (call);
1668: if (GET_CODE (call) == PARALLEL)
1669: {
1670: for (i = XVECLEN (call, 0) - 1; i >= 0; i--)
1671: if (GET_CODE (XVECEXP (call, 0, i)) == SET
1672: && GET_CODE (SET_SRC (XVECEXP (call, 0, i))) == CALL)
1673: break;
1674:
1675: if (i < 0)
1676: abort ();
1677:
1678: call = XVECEXP (call, 0, i);
1679: }
1680:
1681: return insn_dead_p (call, needed, 1);
1682: }
1683: }
1684: return 1;
1685: }
1686:
1687: /* Return 1 if register REGNO was used before it was set.
1688: In other words, if it is live at function entry.
1689: Don't count global regster variables, though. */
1690:
1691: int
1692: regno_uninitialized (regno)
1693: int regno;
1694: {
1695: if (n_basic_blocks == 0
1696: || (regno < FIRST_PSEUDO_REGISTER && global_regs[regno]))
1697: return 0;
1698:
1699: return (basic_block_live_at_start[0][regno / REGSET_ELT_BITS]
1700: & ((REGSET_ELT_TYPE) 1 << (regno % REGSET_ELT_BITS)));
1701: }
1702:
1703: /* 1 if register REGNO was alive at a place where `setjmp' was called
1704: and was set more than once or is an argument.
1705: Such regs may be clobbered by `longjmp'. */
1706:
1707: int
1708: regno_clobbered_at_setjmp (regno)
1709: int regno;
1710: {
1711: if (n_basic_blocks == 0)
1712: return 0;
1713:
1714: return ((reg_n_sets[regno] > 1
1715: || (basic_block_live_at_start[0][regno / REGSET_ELT_BITS]
1716: & ((REGSET_ELT_TYPE) 1 << (regno % REGSET_ELT_BITS))))
1717: && (regs_live_at_setjmp[regno / REGSET_ELT_BITS]
1718: & ((REGSET_ELT_TYPE) 1 << (regno % REGSET_ELT_BITS))));
1719: }
1720:
1721: /* Process the registers that are set within X.
1722: Their bits are set to 1 in the regset DEAD,
1723: because they are dead prior to this insn.
1724:
1725: If INSN is nonzero, it is the insn being processed
1726: and the fact that it is nonzero implies this is the FINAL pass
1727: in propagate_block. In this case, various info about register
1728: usage is stored, LOG_LINKS fields of insns are set up. */
1729:
1730: static void mark_set_1 ();
1731:
1732: static void
1733: mark_set_regs (needed, dead, x, insn, significant)
1734: regset needed;
1735: regset dead;
1736: rtx x;
1737: rtx insn;
1738: regset significant;
1739: {
1740: register RTX_CODE code = GET_CODE (x);
1741:
1742: if (code == SET || code == CLOBBER)
1743: mark_set_1 (needed, dead, x, insn, significant);
1744: else if (code == PARALLEL)
1745: {
1746: register int i;
1747: for (i = XVECLEN (x, 0) - 1; i >= 0; i--)
1748: {
1749: code = GET_CODE (XVECEXP (x, 0, i));
1750: if (code == SET || code == CLOBBER)
1751: mark_set_1 (needed, dead, XVECEXP (x, 0, i), insn, significant);
1752: }
1753: }
1754: }
1755:
1756: /* Process a single SET rtx, X. */
1757:
1758: static void
1759: mark_set_1 (needed, dead, x, insn, significant)
1760: regset needed;
1761: regset dead;
1762: rtx x;
1763: rtx insn;
1764: regset significant;
1765: {
1766: register int regno;
1767: register rtx reg = SET_DEST (x);
1768:
1769: /* Modifying just one hardware register of a multi-reg value
1770: or just a byte field of a register
1771: does not mean the value from before this insn is now dead.
1772: But it does mean liveness of that register at the end of the block
1773: is significant.
1774:
1775: Within mark_set_1, however, we treat it as if the register is
1776: indeed modified. mark_used_regs will, however, also treat this
1777: register as being used. Thus, we treat these insns as setting a
1778: new value for the register as a function of its old value. This
1779: cases LOG_LINKS to be made appropriately and this will help combine. */
1780:
1781: while (GET_CODE (reg) == SUBREG || GET_CODE (reg) == ZERO_EXTRACT
1782: || GET_CODE (reg) == SIGN_EXTRACT
1783: || GET_CODE (reg) == STRICT_LOW_PART)
1784: reg = XEXP (reg, 0);
1785:
1786: /* If we are writing into memory or into a register mentioned in the
1787: address of the last thing stored into memory, show we don't know
1788: what the last store was. If we are writing memory, save the address
1789: unless it is volatile. */
1790: if (GET_CODE (reg) == MEM
1791: || (GET_CODE (reg) == REG
1792: && last_mem_set != 0 && reg_overlap_mentioned_p (reg, last_mem_set)))
1793: last_mem_set = 0;
1794:
1795: if (GET_CODE (reg) == MEM && ! side_effects_p (reg)
1796: /* There are no REG_INC notes for SP, so we can't assume we'll see
1797: everything that invalidates it. To be safe, don't eliminate any
1798: stores though SP; none of them should be redundant anyway. */
1799: && ! reg_mentioned_p (stack_pointer_rtx, reg))
1800: last_mem_set = reg;
1801:
1802: if (GET_CODE (reg) == REG
1803: && (regno = REGNO (reg), regno != FRAME_POINTER_REGNUM)
1804: #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
1805: && regno != HARD_FRAME_POINTER_REGNUM
1806: #endif
1807: #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
1808: && ! (regno == ARG_POINTER_REGNUM && fixed_regs[regno])
1809: #endif
1810: && ! (regno < FIRST_PSEUDO_REGISTER && global_regs[regno]))
1811: /* && regno != STACK_POINTER_REGNUM) -- let's try without this. */
1812: {
1813: register int offset = regno / REGSET_ELT_BITS;
1814: register REGSET_ELT_TYPE bit
1815: = (REGSET_ELT_TYPE) 1 << (regno % REGSET_ELT_BITS);
1816: REGSET_ELT_TYPE all_needed = (needed[offset] & bit);
1817: REGSET_ELT_TYPE some_needed = (needed[offset] & bit);
1818:
1819: /* Mark it as a significant register for this basic block. */
1820: if (significant)
1821: significant[offset] |= bit;
1822:
1823: /* Mark it as as dead before this insn. */
1824: dead[offset] |= bit;
1825:
1826: /* A hard reg in a wide mode may really be multiple registers.
1827: If so, mark all of them just like the first. */
1828: if (regno < FIRST_PSEUDO_REGISTER)
1829: {
1830: int n;
1831:
1832: /* Nothing below is needed for the stack pointer; get out asap.
1833: Eg, log links aren't needed, since combine won't use them. */
1834: if (regno == STACK_POINTER_REGNUM)
1835: return;
1836:
1837: n = HARD_REGNO_NREGS (regno, GET_MODE (reg));
1838: while (--n > 0)
1839: {
1840: if (significant)
1841: significant[(regno + n) / REGSET_ELT_BITS]
1842: |= (REGSET_ELT_TYPE) 1 << ((regno + n) % REGSET_ELT_BITS);
1843: dead[(regno + n) / REGSET_ELT_BITS]
1844: |= (REGSET_ELT_TYPE) 1 << ((regno + n) % REGSET_ELT_BITS);
1845: some_needed
1846: |= (needed[(regno + n) / REGSET_ELT_BITS]
1847: & (REGSET_ELT_TYPE) 1 << ((regno + n) % REGSET_ELT_BITS));
1848: all_needed
1849: &= (needed[(regno + n) / REGSET_ELT_BITS]
1850: & (REGSET_ELT_TYPE) 1 << ((regno + n) % REGSET_ELT_BITS));
1851: }
1852: }
1853: /* Additional data to record if this is the final pass. */
1854: if (insn)
1855: {
1856: register rtx y = reg_next_use[regno];
1857: register int blocknum = BLOCK_NUM (insn);
1858:
1859: /* The next use is no longer "next", since a store intervenes. */
1860: reg_next_use[regno] = 0;
1861:
1862: /* If this is a hard reg, record this function uses the reg. */
1863:
1864: if (regno < FIRST_PSEUDO_REGISTER)
1865: {
1866: register int i;
1867: int endregno = regno + HARD_REGNO_NREGS (regno, GET_MODE (reg));
1868:
1869: for (i = regno; i < endregno; i++)
1870: {
1871: regs_ever_live[i] = 1;
1872: reg_n_sets[i]++;
1873: }
1874: }
1875: else
1876: {
1877: /* Keep track of which basic blocks each reg appears in. */
1878:
1879: if (reg_basic_block[regno] == REG_BLOCK_UNKNOWN)
1880: reg_basic_block[regno] = blocknum;
1881: else if (reg_basic_block[regno] != blocknum)
1882: reg_basic_block[regno] = REG_BLOCK_GLOBAL;
1883:
1884: /* Count (weighted) references, stores, etc. This counts a
1885: register twice if it is modified, but that is correct. */
1886: reg_n_sets[regno]++;
1887:
1888: reg_n_refs[regno] += loop_depth;
1889:
1890: /* The insns where a reg is live are normally counted
1891: elsewhere, but we want the count to include the insn
1892: where the reg is set, and the normal counting mechanism
1893: would not count it. */
1894: reg_live_length[regno]++;
1895: }
1896:
1897: if (all_needed)
1898: {
1899: /* Make a logical link from the next following insn
1900: that uses this register, back to this insn.
1901: The following insns have already been processed.
1902:
1903: We don't build a LOG_LINK for hard registers containing
1904: in ASM_OPERANDs. If these registers get replaced,
1905: we might wind up changing the semantics of the insn,
1906: even if reload can make what appear to be valid assignments
1907: later. */
1908: if (y && (BLOCK_NUM (y) == blocknum)
1909: && (regno >= FIRST_PSEUDO_REGISTER
1910: || asm_noperands (PATTERN (y)) < 0))
1911: LOG_LINKS (y)
1912: = gen_rtx (INSN_LIST, VOIDmode, insn, LOG_LINKS (y));
1913: }
1914: else if (! some_needed)
1915: {
1916: /* Note that dead stores have already been deleted when possible
1917: If we get here, we have found a dead store that cannot
1918: be eliminated (because the same insn does something useful).
1919: Indicate this by marking the reg being set as dying here. */
1920: REG_NOTES (insn)
1921: = gen_rtx (EXPR_LIST, REG_UNUSED, reg, REG_NOTES (insn));
1922: reg_n_deaths[REGNO (reg)]++;
1923: }
1924: else
1925: {
1926: /* This is a case where we have a multi-word hard register
1927: and some, but not all, of the words of the register are
1928: needed in subsequent insns. Write REG_UNUSED notes
1929: for those parts that were not needed. This case should
1930: be rare. */
1931:
1932: int i;
1933:
1934: for (i = HARD_REGNO_NREGS (regno, GET_MODE (reg)) - 1;
1935: i >= 0; i--)
1936: if ((needed[(regno + i) / REGSET_ELT_BITS]
1937: & ((REGSET_ELT_TYPE) 1
1938: << ((regno + i) % REGSET_ELT_BITS))) == 0)
1939: REG_NOTES (insn)
1940: = gen_rtx (EXPR_LIST, REG_UNUSED,
1941: gen_rtx (REG, word_mode, regno + i),
1942: REG_NOTES (insn));
1943: }
1944: }
1945: }
1946: else if (GET_CODE (reg) == REG)
1947: reg_next_use[regno] = 0;
1948:
1949: /* If this is the last pass and this is a SCRATCH, show it will be dying
1950: here and count it. */
1951: else if (GET_CODE (reg) == SCRATCH && insn != 0)
1952: {
1953: REG_NOTES (insn)
1954: = gen_rtx (EXPR_LIST, REG_UNUSED, reg, REG_NOTES (insn));
1955: num_scratch++;
1956: }
1957: }
1958:
1959: #ifdef AUTO_INC_DEC
1960:
1961: /* X is a MEM found in INSN. See if we can convert it into an auto-increment
1962: reference. */
1963:
1964: static void
1965: find_auto_inc (needed, x, insn)
1966: regset needed;
1967: rtx x;
1968: rtx insn;
1969: {
1970: rtx addr = XEXP (x, 0);
1971: int offset = 0;
1972:
1973: /* Here we detect use of an index register which might be good for
1974: postincrement, postdecrement, preincrement, or predecrement. */
1975:
1976: if (GET_CODE (addr) == PLUS && GET_CODE (XEXP (addr, 1)) == CONST_INT)
1977: offset = INTVAL (XEXP (addr, 1)), addr = XEXP (addr, 0);
1978:
1979: if (GET_CODE (addr) == REG)
1980: {
1981: register rtx y;
1982: register int size = GET_MODE_SIZE (GET_MODE (x));
1983: rtx use;
1984: rtx incr;
1985: int regno = REGNO (addr);
1986:
1987: /* Is the next use an increment that might make auto-increment? */
1988: incr = reg_next_use[regno];
1989: if (incr && GET_CODE (PATTERN (incr)) == SET
1990: && BLOCK_NUM (incr) == BLOCK_NUM (insn)
1991: /* Can't add side effects to jumps; if reg is spilled and
1992: reloaded, there's no way to store back the altered value. */
1993: && GET_CODE (insn) != JUMP_INSN
1994: && (y = SET_SRC (PATTERN (incr)), GET_CODE (y) == PLUS)
1995: && XEXP (y, 0) == addr
1996: && GET_CODE (XEXP (y, 1)) == CONST_INT
1997: && (0
1998: #ifdef HAVE_POST_INCREMENT
1999: || (INTVAL (XEXP (y, 1)) == size && offset == 0)
2000: #endif
2001: #ifdef HAVE_POST_DECREMENT
2002: || (INTVAL (XEXP (y, 1)) == - size && offset == 0)
2003: #endif
2004: #ifdef HAVE_PRE_INCREMENT
2005: || (INTVAL (XEXP (y, 1)) == size && offset == size)
2006: #endif
2007: #ifdef HAVE_PRE_DECREMENT
2008: || (INTVAL (XEXP (y, 1)) == - size && offset == - size)
2009: #endif
2010: )
2011: /* Make sure this reg appears only once in this insn. */
2012: && (use = find_use_as_address (PATTERN (insn), addr, offset),
2013: use != 0 && use != (rtx) 1))
2014: {
2015: int win = 0;
2016: rtx q = SET_DEST (PATTERN (incr));
2017:
2018: if (dead_or_set_p (incr, addr))
2019: win = 1;
2020: else if (GET_CODE (q) == REG
2021: /* PREV_INSN used here to check the semi-open interval
2022: [insn,incr). */
2023: && ! reg_used_between_p (q, PREV_INSN (insn), incr))
2024: {
2025: /* We have *p followed sometime later by q = p+size.
2026: Both p and q must be live afterward,
2027: and q is not used between INSN and it's assignment.
2028: Change it to q = p, ...*q..., q = q+size.
2029: Then fall into the usual case. */
2030: rtx insns, temp;
2031:
2032: start_sequence ();
2033: emit_move_insn (q, addr);
2034: insns = get_insns ();
2035: end_sequence ();
2036:
2037: /* If anything in INSNS have UID's that don't fit within the
2038: extra space we allocate earlier, we can't make this auto-inc.
2039: This should never happen. */
2040: for (temp = insns; temp; temp = NEXT_INSN (temp))
2041: {
2042: if (INSN_UID (temp) > max_uid_for_flow)
2043: return;
2044: BLOCK_NUM (temp) = BLOCK_NUM (insn);
2045: }
2046:
2047: emit_insns_before (insns, insn);
2048:
2049: if (basic_block_head[BLOCK_NUM (insn)] == insn)
2050: basic_block_head[BLOCK_NUM (insn)] = insns;
2051:
2052: XEXP (x, 0) = q;
2053: XEXP (y, 0) = q;
2054:
2055: /* INCR will become a NOTE and INSN won't contain a
2056: use of ADDR. If a use of ADDR was just placed in
2057: the insn before INSN, make that the next use.
2058: Otherwise, invalidate it. */
2059: if (GET_CODE (PREV_INSN (insn)) == INSN
2060: && GET_CODE (PATTERN (PREV_INSN (insn))) == SET
2061: && SET_SRC (PATTERN (PREV_INSN (insn))) == addr)
2062: reg_next_use[regno] = PREV_INSN (insn);
2063: else
2064: reg_next_use[regno] = 0;
2065:
2066: addr = q;
2067: regno = REGNO (q);
2068: win = 1;
2069:
2070: /* REGNO is now used in INCR which is below INSN, but
2071: it previously wasn't live here. If we don't mark
2072: it as needed, we'll put a REG_DEAD note for it
2073: on this insn, which is incorrect. */
2074: needed[regno / REGSET_ELT_BITS]
2075: |= (REGSET_ELT_TYPE) 1 << (regno % REGSET_ELT_BITS);
2076:
2077: /* If there are any calls between INSN and INCR, show
2078: that REGNO now crosses them. */
2079: for (temp = insn; temp != incr; temp = NEXT_INSN (temp))
2080: if (GET_CODE (temp) == CALL_INSN)
2081: reg_n_calls_crossed[regno]++;
2082: }
2083:
2084: if (win)
2085: {
2086: /* We have found a suitable auto-increment: do POST_INC around
2087: the register here, and patch out the increment instruction
2088: that follows. */
2089: XEXP (x, 0) = gen_rtx ((INTVAL (XEXP (y, 1)) == size
2090: ? (offset ? PRE_INC : POST_INC)
2091: : (offset ? PRE_DEC : POST_DEC)),
2092: Pmode, addr);
2093:
2094: /* Record that this insn has an implicit side effect. */
2095: REG_NOTES (insn)
2096: = gen_rtx (EXPR_LIST, REG_INC, addr, REG_NOTES (insn));
2097:
2098: /* Modify the old increment-insn to simply copy
2099: the already-incremented value of our register. */
2100: SET_SRC (PATTERN (incr)) = addr;
2101: /* Indicate insn must be re-recognized. */
2102: INSN_CODE (incr) = -1;
2103:
2104: /* If that makes it a no-op (copying the register into itself)
2105: then delete it so it won't appear to be a "use" and a "set"
2106: of this register. */
2107: if (SET_DEST (PATTERN (incr)) == addr)
2108: {
2109: PUT_CODE (incr, NOTE);
2110: NOTE_LINE_NUMBER (incr) = NOTE_INSN_DELETED;
2111: NOTE_SOURCE_FILE (incr) = 0;
2112: }
2113:
2114: if (regno >= FIRST_PSEUDO_REGISTER)
2115: {
2116: /* Count an extra reference to the reg. When a reg is
2117: incremented, spilling it is worse, so we want to make
2118: that less likely. */
2119: reg_n_refs[regno] += loop_depth;
2120: /* Count the increment as a setting of the register,
2121: even though it isn't a SET in rtl. */
2122: reg_n_sets[regno]++;
2123: }
2124: }
2125: }
2126: }
2127: }
2128: #endif /* AUTO_INC_DEC */
2129:
2130: /* Scan expression X and store a 1-bit in LIVE for each reg it uses.
2131: This is done assuming the registers needed from X
2132: are those that have 1-bits in NEEDED.
2133:
2134: On the final pass, FINAL is 1. This means try for autoincrement
2135: and count the uses and deaths of each pseudo-reg.
2136:
2137: INSN is the containing instruction. If INSN is dead, this function is not
2138: called. */
2139:
2140: static void
2141: mark_used_regs (needed, live, x, final, insn)
2142: regset needed;
2143: regset live;
2144: rtx x;
2145: rtx insn;
2146: int final;
2147: {
2148: register RTX_CODE code;
2149: register int regno;
2150: int i;
2151:
2152: retry:
2153: code = GET_CODE (x);
2154: switch (code)
2155: {
2156: case LABEL_REF:
2157: case SYMBOL_REF:
2158: case CONST_INT:
2159: case CONST:
2160: case CONST_DOUBLE:
2161: case PC:
2162: case ADDR_VEC:
2163: case ADDR_DIFF_VEC:
2164: case ASM_INPUT:
2165: return;
2166:
2167: #ifdef HAVE_cc0
2168: case CC0:
2169: cc0_live = 1;
2170: return;
2171: #endif
2172:
2173: case CLOBBER:
2174: /* If we are clobbering a MEM, mark any registers inside the address
2175: as being used. */
2176: if (GET_CODE (XEXP (x, 0)) == MEM)
2177: mark_used_regs (needed, live, XEXP (XEXP (x, 0), 0), final, insn);
2178: return;
2179:
2180: case MEM:
2181: /* Invalidate the data for the last MEM stored. We could do this only
2182: if the addresses conflict, but this doesn't seem worthwhile. */
2183: last_mem_set = 0;
2184:
2185: #ifdef AUTO_INC_DEC
2186: if (final)
2187: find_auto_inc (needed, x, insn);
2188: #endif
2189: break;
2190:
2191: case REG:
2192: /* See a register other than being set
2193: => mark it as needed. */
2194:
2195: regno = REGNO (x);
2196: {
2197: register int offset = regno / REGSET_ELT_BITS;
2198: register REGSET_ELT_TYPE bit
2199: = (REGSET_ELT_TYPE) 1 << (regno % REGSET_ELT_BITS);
2200: REGSET_ELT_TYPE all_needed = needed[offset] & bit;
2201: REGSET_ELT_TYPE some_needed = needed[offset] & bit;
2202:
2203: live[offset] |= bit;
2204: /* A hard reg in a wide mode may really be multiple registers.
2205: If so, mark all of them just like the first. */
2206: if (regno < FIRST_PSEUDO_REGISTER)
2207: {
2208: int n;
2209:
2210: /* For stack ptr or fixed arg pointer,
2211: nothing below can be necessary, so waste no more time. */
2212: if (regno == STACK_POINTER_REGNUM
2213: #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
2214: || regno == HARD_FRAME_POINTER_REGNUM
2215: #endif
2216: #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
2217: || (regno == ARG_POINTER_REGNUM && fixed_regs[regno])
2218: #endif
2219: || regno == FRAME_POINTER_REGNUM)
2220: {
2221: /* If this is a register we are going to try to eliminate,
2222: don't mark it live here. If we are successful in
2223: eliminating it, it need not be live unless it is used for
2224: pseudos, in which case it will have been set live when
2225: it was allocated to the pseudos. If the register will not
2226: be eliminated, reload will set it live at that point. */
2227:
2228: if (! TEST_HARD_REG_BIT (elim_reg_set, regno))
2229: regs_ever_live[regno] = 1;
2230: return;
2231: }
2232: /* No death notes for global register variables;
2233: their values are live after this function exits. */
2234: if (global_regs[regno])
2235: {
2236: if (final)
2237: reg_next_use[regno] = insn;
2238: return;
2239: }
2240:
2241: n = HARD_REGNO_NREGS (regno, GET_MODE (x));
2242: while (--n > 0)
2243: {
2244: live[(regno + n) / REGSET_ELT_BITS]
2245: |= (REGSET_ELT_TYPE) 1 << ((regno + n) % REGSET_ELT_BITS);
2246: some_needed
2247: |= (needed[(regno + n) / REGSET_ELT_BITS]
2248: & (REGSET_ELT_TYPE) 1 << ((regno + n) % REGSET_ELT_BITS));
2249: all_needed
2250: &= (needed[(regno + n) / REGSET_ELT_BITS]
2251: & (REGSET_ELT_TYPE) 1 << ((regno + n) % REGSET_ELT_BITS));
2252: }
2253: }
2254: if (final)
2255: {
2256: /* Record where each reg is used, so when the reg
2257: is set we know the next insn that uses it. */
2258:
2259: reg_next_use[regno] = insn;
2260:
2261: if (regno < FIRST_PSEUDO_REGISTER)
2262: {
2263: /* If a hard reg is being used,
2264: record that this function does use it. */
2265:
2266: i = HARD_REGNO_NREGS (regno, GET_MODE (x));
2267: if (i == 0)
2268: i = 1;
2269: do
2270: regs_ever_live[regno + --i] = 1;
2271: while (i > 0);
2272: }
2273: else
2274: {
2275: /* Keep track of which basic block each reg appears in. */
2276:
2277: register int blocknum = BLOCK_NUM (insn);
2278:
2279: if (reg_basic_block[regno] == REG_BLOCK_UNKNOWN)
2280: reg_basic_block[regno] = blocknum;
2281: else if (reg_basic_block[regno] != blocknum)
2282: reg_basic_block[regno] = REG_BLOCK_GLOBAL;
2283:
2284: /* Count (weighted) number of uses of each reg. */
2285:
2286: reg_n_refs[regno] += loop_depth;
2287: }
2288:
2289: /* Record and count the insns in which a reg dies.
2290: If it is used in this insn and was dead below the insn
2291: then it dies in this insn. If it was set in this insn,
2292: we do not make a REG_DEAD note; likewise if we already
2293: made such a note. */
2294:
2295: if (! all_needed
2296: && ! dead_or_set_p (insn, x)
2297: #if 0
2298: && (regno >= FIRST_PSEUDO_REGISTER || ! fixed_regs[regno])
2299: #endif
2300: )
2301: {
2302: /* If none of the words in X is needed, make a REG_DEAD
2303: note. Otherwise, we must make partial REG_DEAD notes. */
2304: if (! some_needed)
2305: {
2306: REG_NOTES (insn)
2307: = gen_rtx (EXPR_LIST, REG_DEAD, x, REG_NOTES (insn));
2308: reg_n_deaths[regno]++;
2309: }
2310: else
2311: {
2312: int i;
2313:
2314: /* Don't make a REG_DEAD note for a part of a register
2315: that is set in the insn. */
2316:
2317: for (i = HARD_REGNO_NREGS (regno, GET_MODE (x)) - 1;
2318: i >= 0; i--)
2319: if ((needed[(regno + i) / REGSET_ELT_BITS]
2320: & ((REGSET_ELT_TYPE) 1
2321: << ((regno + i) % REGSET_ELT_BITS))) == 0
2322: && ! dead_or_set_regno_p (insn, regno + i))
2323: REG_NOTES (insn)
2324: = gen_rtx (EXPR_LIST, REG_DEAD,
2325: gen_rtx (REG, word_mode, regno + i),
2326: REG_NOTES (insn));
2327: }
2328: }
2329: }
2330: }
2331: return;
2332:
2333: case SET:
2334: {
2335: register rtx testreg = SET_DEST (x);
2336: int mark_dest = 0;
2337:
2338: /* If storing into MEM, don't show it as being used. But do
2339: show the address as being used. */
2340: if (GET_CODE (testreg) == MEM)
2341: {
2342: #ifdef AUTO_INC_DEC
2343: if (final)
2344: find_auto_inc (needed, testreg, insn);
2345: #endif
2346: mark_used_regs (needed, live, XEXP (testreg, 0), final, insn);
2347: mark_used_regs (needed, live, SET_SRC (x), final, insn);
2348: return;
2349: }
2350:
2351: /* Storing in STRICT_LOW_PART is like storing in a reg
2352: in that this SET might be dead, so ignore it in TESTREG.
2353: but in some other ways it is like using the reg.
2354:
2355: Storing in a SUBREG or a bit field is like storing the entire
2356: register in that if the register's value is not used
2357: then this SET is not needed. */
2358: while (GET_CODE (testreg) == STRICT_LOW_PART
2359: || GET_CODE (testreg) == ZERO_EXTRACT
2360: || GET_CODE (testreg) == SIGN_EXTRACT
2361: || GET_CODE (testreg) == SUBREG)
2362: {
2363: /* Modifying a single register in an alternate mode
2364: does not use any of the old value. But these other
2365: ways of storing in a register do use the old value. */
2366: if (GET_CODE (testreg) == SUBREG
2367: && !(REG_SIZE (SUBREG_REG (testreg)) > REG_SIZE (testreg)))
2368: ;
2369: else
2370: mark_dest = 1;
2371:
2372: testreg = XEXP (testreg, 0);
2373: }
2374:
2375: /* If this is a store into a register,
2376: recursively scan the value being stored. */
2377:
2378: if (GET_CODE (testreg) == REG
2379: && (regno = REGNO (testreg), regno != FRAME_POINTER_REGNUM)
2380: #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
2381: && regno != HARD_FRAME_POINTER_REGNUM
2382: #endif
2383: #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
2384: && ! (regno == ARG_POINTER_REGNUM && fixed_regs[regno])
2385: #endif
2386: )
2387: /* We used to exclude global_regs here, but that seems wrong.
2388: Storing in them is like storing in mem. */
2389: {
2390: mark_used_regs (needed, live, SET_SRC (x), final, insn);
2391: if (mark_dest)
2392: mark_used_regs (needed, live, SET_DEST (x), final, insn);
2393: return;
2394: }
2395: }
2396: break;
2397:
2398: case RETURN:
2399: /* If exiting needs the right stack value, consider this insn as
2400: using the stack pointer. In any event, consider it as using
2401: all global registers. */
2402:
2403: #ifdef EXIT_IGNORE_STACK
2404: if (! EXIT_IGNORE_STACK
2405: || (! FRAME_POINTER_REQUIRED && flag_omit_frame_pointer))
2406: #endif
2407: live[STACK_POINTER_REGNUM / REGSET_ELT_BITS]
2408: |= (REGSET_ELT_TYPE) 1 << (STACK_POINTER_REGNUM % REGSET_ELT_BITS);
2409:
2410: for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
2411: if (global_regs[i])
2412: live[i / REGSET_ELT_BITS]
2413: |= (REGSET_ELT_TYPE) 1 << (i % REGSET_ELT_BITS);
2414: break;
2415: }
2416:
2417: /* Recursively scan the operands of this expression. */
2418:
2419: {
2420: register char *fmt = GET_RTX_FORMAT (code);
2421: register int i;
2422:
2423: for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
2424: {
2425: if (fmt[i] == 'e')
2426: {
2427: /* Tail recursive case: save a function call level. */
2428: if (i == 0)
2429: {
2430: x = XEXP (x, 0);
2431: goto retry;
2432: }
2433: mark_used_regs (needed, live, XEXP (x, i), final, insn);
2434: }
2435: else if (fmt[i] == 'E')
2436: {
2437: register int j;
2438: for (j = 0; j < XVECLEN (x, i); j++)
2439: mark_used_regs (needed, live, XVECEXP (x, i, j), final, insn);
2440: }
2441: }
2442: }
2443: }
2444:
2445: #ifdef AUTO_INC_DEC
2446:
2447: static int
2448: try_pre_increment_1 (insn)
2449: rtx insn;
2450: {
2451: /* Find the next use of this reg. If in same basic block,
2452: make it do pre-increment or pre-decrement if appropriate. */
2453: rtx x = PATTERN (insn);
2454: HOST_WIDE_INT amount = ((GET_CODE (SET_SRC (x)) == PLUS ? 1 : -1)
2455: * INTVAL (XEXP (SET_SRC (x), 1)));
2456: int regno = REGNO (SET_DEST (x));
2457: rtx y = reg_next_use[regno];
2458: if (y != 0
2459: && BLOCK_NUM (y) == BLOCK_NUM (insn)
2460: && try_pre_increment (y, SET_DEST (PATTERN (insn)),
2461: amount))
2462: {
2463: /* We have found a suitable auto-increment
2464: and already changed insn Y to do it.
2465: So flush this increment-instruction. */
2466: PUT_CODE (insn, NOTE);
2467: NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED;
2468: NOTE_SOURCE_FILE (insn) = 0;
2469: /* Count a reference to this reg for the increment
2470: insn we are deleting. When a reg is incremented.
2471: spilling it is worse, so we want to make that
2472: less likely. */
2473: if (regno >= FIRST_PSEUDO_REGISTER)
2474: {
2475: reg_n_refs[regno] += loop_depth;
2476: reg_n_sets[regno]++;
2477: }
2478: return 1;
2479: }
2480: return 0;
2481: }
2482:
2483: /* Try to change INSN so that it does pre-increment or pre-decrement
2484: addressing on register REG in order to add AMOUNT to REG.
2485: AMOUNT is negative for pre-decrement.
2486: Returns 1 if the change could be made.
2487: This checks all about the validity of the result of modifying INSN. */
2488:
2489: static int
2490: try_pre_increment (insn, reg, amount)
2491: rtx insn, reg;
2492: HOST_WIDE_INT amount;
2493: {
2494: register rtx use;
2495:
2496: /* Nonzero if we can try to make a pre-increment or pre-decrement.
2497: For example, addl $4,r1; movl (r1),... can become movl +(r1),... */
2498: int pre_ok = 0;
2499: /* Nonzero if we can try to make a post-increment or post-decrement.
2500: For example, addl $4,r1; movl -4(r1),... can become movl (r1)+,...
2501: It is possible for both PRE_OK and POST_OK to be nonzero if the machine
2502: supports both pre-inc and post-inc, or both pre-dec and post-dec. */
2503: int post_ok = 0;
2504:
2505: /* Nonzero if the opportunity actually requires post-inc or post-dec. */
2506: int do_post = 0;
2507:
2508: /* From the sign of increment, see which possibilities are conceivable
2509: on this target machine. */
2510: #ifdef HAVE_PRE_INCREMENT
2511: if (amount > 0)
2512: pre_ok = 1;
2513: #endif
2514: #ifdef HAVE_POST_INCREMENT
2515: if (amount > 0)
2516: post_ok = 1;
2517: #endif
2518:
2519: #ifdef HAVE_PRE_DECREMENT
2520: if (amount < 0)
2521: pre_ok = 1;
2522: #endif
2523: #ifdef HAVE_POST_DECREMENT
2524: if (amount < 0)
2525: post_ok = 1;
2526: #endif
2527:
2528: if (! (pre_ok || post_ok))
2529: return 0;
2530:
2531: /* It is not safe to add a side effect to a jump insn
2532: because if the incremented register is spilled and must be reloaded
2533: there would be no way to store the incremented value back in memory. */
2534:
2535: if (GET_CODE (insn) == JUMP_INSN)
2536: return 0;
2537:
2538: use = 0;
2539: if (pre_ok)
2540: use = find_use_as_address (PATTERN (insn), reg, 0);
2541: if (post_ok && (use == 0 || use == (rtx) 1))
2542: {
2543: use = find_use_as_address (PATTERN (insn), reg, -amount);
2544: do_post = 1;
2545: }
2546:
2547: if (use == 0 || use == (rtx) 1)
2548: return 0;
2549:
2550: if (GET_MODE_SIZE (GET_MODE (use)) != (amount > 0 ? amount : - amount))
2551: return 0;
2552:
2553: XEXP (use, 0) = gen_rtx (amount > 0
2554: ? (do_post ? POST_INC : PRE_INC)
2555: : (do_post ? POST_DEC : PRE_DEC),
2556: Pmode, reg);
2557:
2558: /* Record that this insn now has an implicit side effect on X. */
2559: REG_NOTES (insn) = gen_rtx (EXPR_LIST, REG_INC, reg, REG_NOTES (insn));
2560: return 1;
2561: }
2562:
2563: #endif /* AUTO_INC_DEC */
2564:
2565: /* Find the place in the rtx X where REG is used as a memory address.
2566: Return the MEM rtx that so uses it.
2567: If PLUSCONST is nonzero, search instead for a memory address equivalent to
2568: (plus REG (const_int PLUSCONST)).
2569:
2570: If such an address does not appear, return 0.
2571: If REG appears more than once, or is used other than in such an address,
2572: return (rtx)1. */
2573:
2574: static rtx
2575: find_use_as_address (x, reg, plusconst)
2576: register rtx x;
2577: rtx reg;
2578: int plusconst;
2579: {
2580: enum rtx_code code = GET_CODE (x);
2581: char *fmt = GET_RTX_FORMAT (code);
2582: register int i;
2583: register rtx value = 0;
2584: register rtx tem;
2585:
2586: if (code == MEM && XEXP (x, 0) == reg && plusconst == 0)
2587: return x;
2588:
2589: if (code == MEM && GET_CODE (XEXP (x, 0)) == PLUS
2590: && XEXP (XEXP (x, 0), 0) == reg
2591: && GET_CODE (XEXP (XEXP (x, 0), 1)) == CONST_INT
2592: && INTVAL (XEXP (XEXP (x, 0), 1)) == plusconst)
2593: return x;
2594:
2595: if (code == SIGN_EXTRACT || code == ZERO_EXTRACT)
2596: {
2597: /* If REG occurs inside a MEM used in a bit-field reference,
2598: that is unacceptable. */
2599: if (find_use_as_address (XEXP (x, 0), reg, 0) != 0)
2600: return (rtx) (HOST_WIDE_INT) 1;
2601: }
2602:
2603: if (x == reg)
2604: return (rtx) (HOST_WIDE_INT) 1;
2605:
2606: for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
2607: {
2608: if (fmt[i] == 'e')
2609: {
2610: tem = find_use_as_address (XEXP (x, i), reg, plusconst);
2611: if (value == 0)
2612: value = tem;
2613: else if (tem != 0)
2614: return (rtx) (HOST_WIDE_INT) 1;
2615: }
2616: if (fmt[i] == 'E')
2617: {
2618: register int j;
2619: for (j = XVECLEN (x, i) - 1; j >= 0; j--)
2620: {
2621: tem = find_use_as_address (XVECEXP (x, i, j), reg, plusconst);
2622: if (value == 0)
2623: value = tem;
2624: else if (tem != 0)
2625: return (rtx) (HOST_WIDE_INT) 1;
2626: }
2627: }
2628: }
2629:
2630: return value;
2631: }
2632:
2633: /* Write information about registers and basic blocks into FILE.
2634: This is part of making a debugging dump. */
2635:
2636: void
2637: dump_flow_info (file)
2638: FILE *file;
2639: {
2640: register int i;
2641: static char *reg_class_names[] = REG_CLASS_NAMES;
2642:
2643: fprintf (file, "%d registers.\n", max_regno);
2644:
2645: for (i = FIRST_PSEUDO_REGISTER; i < max_regno; i++)
2646: if (reg_n_refs[i])
2647: {
2648: enum reg_class class, altclass;
2649: fprintf (file, "\nRegister %d used %d times across %d insns",
2650: i, reg_n_refs[i], reg_live_length[i]);
2651: if (reg_basic_block[i] >= 0)
2652: fprintf (file, " in block %d", reg_basic_block[i]);
2653: if (reg_n_deaths[i] != 1)
2654: fprintf (file, "; dies in %d places", reg_n_deaths[i]);
2655: if (reg_n_calls_crossed[i] == 1)
2656: fprintf (file, "; crosses 1 call");
2657: else if (reg_n_calls_crossed[i])
2658: fprintf (file, "; crosses %d calls", reg_n_calls_crossed[i]);
2659: if (PSEUDO_REGNO_BYTES (i) != UNITS_PER_WORD)
2660: fprintf (file, "; %d bytes", PSEUDO_REGNO_BYTES (i));
2661: class = reg_preferred_class (i);
2662: altclass = reg_alternate_class (i);
2663: if (class != GENERAL_REGS || altclass != ALL_REGS)
2664: {
2665: if (altclass == ALL_REGS || class == ALL_REGS)
2666: fprintf (file, "; pref %s", reg_class_names[(int) class]);
2667: else if (altclass == NO_REGS)
2668: fprintf (file, "; %s or none", reg_class_names[(int) class]);
2669: else
2670: fprintf (file, "; pref %s, else %s",
2671: reg_class_names[(int) class],
2672: reg_class_names[(int) altclass]);
2673: }
2674: if (REGNO_POINTER_FLAG (i))
2675: fprintf (file, "; pointer");
2676: fprintf (file, ".\n");
2677: }
2678: fprintf (file, "\n%d basic blocks.\n", n_basic_blocks);
2679: for (i = 0; i < n_basic_blocks; i++)
2680: {
2681: register rtx head, jump;
2682: register int regno;
2683: fprintf (file, "\nBasic block %d: first insn %d, last %d.\n",
2684: i,
2685: INSN_UID (basic_block_head[i]),
2686: INSN_UID (basic_block_end[i]));
2687: /* The control flow graph's storage is freed
2688: now when flow_analysis returns.
2689: Don't try to print it if it is gone. */
2690: if (basic_block_drops_in)
2691: {
2692: fprintf (file, "Reached from blocks: ");
2693: head = basic_block_head[i];
2694: if (GET_CODE (head) == CODE_LABEL)
2695: for (jump = LABEL_REFS (head);
2696: jump != head;
2697: jump = LABEL_NEXTREF (jump))
2698: {
2699: register int from_block = BLOCK_NUM (CONTAINING_INSN (jump));
2700: fprintf (file, " %d", from_block);
2701: }
2702: if (basic_block_drops_in[i])
2703: fprintf (file, " previous");
2704: }
2705: fprintf (file, "\nRegisters live at start:");
2706: for (regno = 0; regno < max_regno; regno++)
2707: {
2708: register int offset = regno / REGSET_ELT_BITS;
2709: register REGSET_ELT_TYPE bit
2710: = (REGSET_ELT_TYPE) 1 << (regno % REGSET_ELT_BITS);
2711: if (basic_block_live_at_start[i][offset] & bit)
2712: fprintf (file, " %d", regno);
2713: }
2714: fprintf (file, "\n");
2715: }
2716: fprintf (file, "\n");
2717: }
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