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