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