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1.1 root 1: /* Data flow analysis for GNU compiler.
1.1.1.2 root 2: Copyright (C) 1987, 1988 Free Software Foundation, Inc.
1.1 root 3:
4: This file is part of GNU CC.
5:
6: GNU CC is distributed in the hope that it will be useful,
7: but WITHOUT ANY WARRANTY. No author or distributor
8: accepts responsibility to anyone for the consequences of using it
9: or for whether it serves any particular purpose or works at all,
10: unless he says so in writing. Refer to the GNU CC General Public
11: License for full details.
12:
13: Everyone is granted permission to copy, modify and redistribute
14: GNU CC, but only under the conditions described in the
15: GNU CC General Public License. A copy of this license is
16: supposed to have been given to you along with GNU CC so you
17: can know your rights and responsibilities. It should be in a
18: file named COPYING. Among other things, the copyright notice
19: and this notice must be preserved on all copies. */
20:
21:
22: /* This file contains the data flow analysis pass of the compiler.
23: It computes data flow information
24: which tells combine_instructions which insns to consider combining
25: and controls register allocation.
26:
27: Additional data flow information that is too bulky to record
28: is generated during the analysis, and is used at that time to
29: create autoincrement and autodecrement addressing.
30:
31: The first step is dividing the function into basic blocks.
32: find_basic_blocks does this. Then life_analysis determines
33: where each register is live and where it is dead.
34:
35: ** find_basic_blocks **
36:
37: find_basic_blocks divides the current function's rtl
38: into basic blocks. It records the beginnings and ends of the
39: basic blocks in the vectors basic_block_head and basic_block_end,
40: and the number of blocks in n_basic_blocks.
41:
42: find_basic_blocks also finds any unreachable loops
43: and deletes them.
44:
45: ** life_analysis **
46:
47: life_analysis is called immediately after find_basic_blocks.
48: It uses the basic block information to determine where each
49: hard or pseudo register is live.
50:
51: ** live-register info **
52:
53: The information about where each register is live is in two parts:
54: the REG_NOTES of insns, and the vector basic_block_live_at_start.
55:
56: basic_block_live_at_start has an element for each basic block,
57: and the element is a bit-vector with a bit for each hard or pseudo
58: register. The bit is 1 if the register is live at the beginning
59: of the basic block.
60:
61: To each insn's REG_NOTES is added an element for each register
62: that is live before the insn or set by the insn, but is dead
63: after the insn.
64:
65: To determine which registers are live after any insn, one can
66: start from the beginning of the basic block and scan insns, noting
67: which registers are set by each insn and which die there.
68:
69: ** Other actions of life_analysis **
70:
71: life_analysis sets up the LOG_LINKS fields of insns because the
72: information needed to do so is readily available.
73:
74: life_analysis deletes insns whose only effect is to store a value
75: that is never used.
76:
77: life_analysis notices cases where a reference to a register as
78: a memory address can be combined with a preceding or following
79: incrementation or decrementation of the register. The separate
80: instruction to increment or decrement is deleted and the address
81: is changed to a POST_INC or similar rtx.
82:
83: Each time an incrementing or decrementing address is created,
84: a REG_INC element is added to the insn's REG_NOTES list.
85:
86: life_analysis fills in certain vectors containing information about
87: register usage: reg_n_refs, reg_n_deaths, reg_n_sets,
88: reg_live_length, reg_crosses_call and reg_basic_block. */
89:
90: #include <stdio.h>
91: #include "config.h"
92: #include "rtl.h"
93: #include "basic-block.h"
94: #include "regs.h"
1.1.1.2 root 95: #include "hard-reg-set.h"
96: #include "flags.h"
1.1 root 97:
98: /* Get the basic block number of an insn.
99: This info should not be expected to remain available
100: after the end of life_analysis. */
101:
102: #define BLOCK_NUM(INSN) uid_block_number[INSN_UID (INSN)]
103:
104: /* This is where the BLOCK_NUM values are really stored.
105: This is set up by find_basic_blocks and used there and in life_analysis,
106: and then freed. */
107:
108: static short *uid_block_number;
109:
1.1.1.2 root 110: /* INSN_VOLATILE (insn) is 1 if the insn refers to anything volatile. */
111:
112: #define INSN_VOLATILE(INSN) uid_volatile[INSN_UID (INSN)]
113: static char *uid_volatile;
114:
1.1 root 115: /* Number of basic blocks in the current function. */
116:
117: int n_basic_blocks;
118:
119: /* Maximum register number used in this function, plus one. */
120:
121: int max_regno;
122:
123: /* Indexed by n, gives number of basic block that (REG n) is used in.
124: Or gives -2 if (REG n) is used in more than one basic block.
125: Or -1 if it has not yet been seen so no basic block is known.
126: This information remains valid for the rest of the compilation
127: of the current function; it is used to control register allocation. */
128:
1.1.1.4 root 129: #define REG_BLOCK_UNKNOWN -1
130: #define REG_BLOCK_GLOBAL -2
1.1 root 131: short *reg_basic_block;
132:
133: /* Indexed by n, gives number of times (REG n) is used or set, each
134: weighted by its loop-depth.
135: This information remains valid for the rest of the compilation
136: of the current function; it is used to control register allocation. */
137:
138: short *reg_n_refs;
139:
140: /* Indexed by n, gives number of times (REG n) is set.
141: This information remains valid for the rest of the compilation
142: of the current function; it is used to control register allocation. */
143:
144: short *reg_n_sets;
145:
146: /* Indexed by N, gives number of places register N dies.
147: This information remains valid for the rest of the compilation
148: of the current function; it is used to control register allocation. */
149:
150: short *reg_n_deaths;
151:
152: /* Indexed by N, gives 1 if that reg is live across any CALL_INSNs.
153: This information remains valid for the rest of the compilation
154: of the current function; it is used to control register allocation. */
155:
156: char *reg_crosses_call;
157:
158: /* Total number of instructions at which (REG n) is live.
159: The larger this is, the less priority (REG n) gets for
160: allocation in a real register.
161: This information remains valid for the rest of the compilation
1.1.1.2 root 162: of the current function; it is used to control register allocation.
163:
164: local-alloc.c may alter this number to change the priority.
165:
166: Negative values are special.
167: -1 is used to mark a pseudo reg which has a constant or memory equivalent
168: and is used infrequently enough that it should not get a hard register.
169: -2 is used to mark a pseudo reg for a parameter, when a frame pointer
170: is not required. global-alloc.c makes an allocno for this but does
171: not try to assign a hard register to it. */
1.1 root 172:
173: int *reg_live_length;
174:
175: /* Element N is the next insn that uses (hard or pseudo) register number N
176: within the current basic block; or zero, if there is no such insn.
177: This is valid only during the final backward scan in propagate_block. */
178:
179: static rtx *reg_next_use;
180:
181: /* Size of a regset for the current function,
182: in (1) bytes and (2) elements. */
183:
184: int regset_bytes;
185: int regset_size;
186:
187: /* Element N is first insn in basic block N.
188: This info lasts until we finish compiling the function. */
189:
190: rtx *basic_block_head;
191:
192: /* Element N is last insn in basic block N.
193: This info lasts until we finish compiling the function. */
194:
195: rtx *basic_block_end;
196:
197: /* Element N is a regset describing the registers live
198: at the start of basic block N.
199: This info lasts until we finish compiling the function. */
200:
201: regset *basic_block_live_at_start;
202:
1.1.1.2 root 203: /* Regset of regs live when calls to `setjmp'-like functions happen. */
204:
205: regset regs_live_at_setjmp;
206:
1.1 root 207: /* Element N is nonzero if control can drop into basic block N
208: from the preceding basic block. Freed after life_analysis. */
209:
1.1.1.2 root 210: static char *basic_block_drops_in;
1.1 root 211:
212: /* Element N is depth within loops of basic block number N.
213: Freed after life_analysis. */
214:
1.1.1.2 root 215: static short *basic_block_loop_depth;
1.1 root 216:
217: /* Element N nonzero if basic block N can actually be reached.
218: Vector exists only during find_basic_blocks. */
219:
1.1.1.2 root 220: static char *block_live_static;
1.1 root 221:
222: /* Depth within loops of basic block being scanned for lifetime analysis,
223: plus one. This is the weight attached to references to registers. */
224:
1.1.1.2 root 225: static int loop_depth;
226:
227: /* Define AUTO_INC_DEC if machine has any kind of incrementing
228: or decrementing addressing. */
229:
230: #ifdef HAVE_PRE_DECREMENT
231: #define AUTO_INC_DEC
232: #endif
233:
234: #ifdef HAVE_PRE_INCREMENT
235: #define AUTO_INC_DEC
236: #endif
237:
238: #ifdef HAVE_POST_DECREMENT
239: #define AUTO_INC_DEC
240: #endif
241:
242: #ifdef HAVE_POST_INCREMENT
243: #define AUTO_INC_DEC
244: #endif
1.1 root 245:
246: /* Forward declarations */
247: static void find_basic_blocks ();
248: static void life_analysis ();
249: static void mark_label_ref ();
250: void allocate_for_life_analysis (); /* Used also in stupid_life_analysis */
251: static void init_regset_vector ();
252: static void propagate_block ();
253: static void mark_set_regs ();
254: static void mark_used_regs ();
255: static int insn_dead_p ();
256: static int try_pre_increment ();
257: static int try_pre_increment_1 ();
258: static rtx find_use_as_address ();
1.1.1.2 root 259: void dump_flow_info ();
1.1 root 260:
261: /* Find basic blocks of the current function and perform data flow analysis.
262: F is the first insn of the function and NREGS the number of register numbers
263: in use. */
264:
265: void
266: flow_analysis (f, nregs, file)
267: rtx f;
268: int nregs;
269: FILE *file;
270: {
271: register rtx insn;
272: register int i;
273: register int max_uid = 0;
274:
275: /* Count the basic blocks. Also find maximum insn uid value used. */
276:
277: {
278: register RTX_CODE prev_code = JUMP_INSN;
279: register RTX_CODE code;
280:
281: for (insn = f, i = 0; insn; insn = NEXT_INSN (insn))
282: {
283: code = GET_CODE (insn);
284: if (INSN_UID (insn) > max_uid)
285: max_uid = INSN_UID (insn);
286: if (code == CODE_LABEL
287: || (prev_code != INSN && prev_code != CALL_INSN
288: && prev_code != CODE_LABEL
289: && (code == INSN || code == CALL_INSN || code == JUMP_INSN)))
290: i++;
291: if (code != NOTE)
292: prev_code = code;
293: }
294: }
295:
296: /* Allocate some tables that last till end of compiling this function
297: and some needed only in find_basic_blocks and life_analysis. */
298:
299: n_basic_blocks = i;
300: basic_block_head = (rtx *) oballoc (n_basic_blocks * sizeof (rtx));
301: basic_block_end = (rtx *) oballoc (n_basic_blocks * sizeof (rtx));
302: basic_block_drops_in = (char *) alloca (n_basic_blocks);
303: basic_block_loop_depth = (short *) alloca (n_basic_blocks * sizeof (short));
304: uid_block_number = (short *) alloca ((max_uid + 1) * sizeof (short));
1.1.1.2 root 305: uid_volatile = (char *) alloca (max_uid + 1);
306: bzero (uid_volatile, max_uid + 1);
1.1 root 307:
308: find_basic_blocks (f);
309: life_analysis (f, nregs);
310: if (file)
311: dump_flow_info (file);
312:
313: basic_block_drops_in = 0;
314: uid_block_number = 0;
315: basic_block_loop_depth = 0;
316: }
317:
318: /* Find all basic blocks of the function whose first insn is F.
319: Store the correct data in the tables that describe the basic blocks,
320: set up the chains of references for each CODE_LABEL, and
321: delete any entire basic blocks that cannot be reached. */
322:
323: static void
324: find_basic_blocks (f)
325: rtx f;
326: {
327: register rtx insn;
328: register int i;
329:
330: /* Initialize the ref chain of each label to 0. */
331: /* Record where all the blocks start and end and their depth in loops. */
332: /* For each insn, record the block it is in. */
333:
334: {
335: register RTX_CODE prev_code = JUMP_INSN;
336: register RTX_CODE code;
337: int depth = 1;
338:
339: for (insn = f, i = -1; insn; insn = NEXT_INSN (insn))
340: {
341: code = GET_CODE (insn);
342: if (code == NOTE)
343: {
344: if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG)
345: depth++;
346: else if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_END)
347: depth--;
348: }
349: else if (code == CODE_LABEL
350: || (prev_code != INSN && prev_code != CALL_INSN
351: && prev_code != CODE_LABEL
352: && (code == INSN || code == CALL_INSN || code == JUMP_INSN)))
353: {
354: basic_block_head[++i] = insn;
355: basic_block_end[i] = insn;
356: basic_block_loop_depth[i] = depth;
357: if (code == CODE_LABEL)
358: LABEL_REFS (insn) = insn;
359: }
360: else if (code == INSN || code == CALL_INSN || code == JUMP_INSN)
361: basic_block_end[i] = insn;
362: BLOCK_NUM (insn) = i;
363: if (code != NOTE)
364: prev_code = code;
365: }
1.1.1.4 root 366: if (i + 1 != n_basic_blocks)
367: abort ();
1.1 root 368: }
369:
370: /* Record which basic blocks control can drop in to. */
371:
372: {
373: register int i;
374: for (i = 0; i < n_basic_blocks; i++)
375: {
376: register rtx insn = PREV_INSN (basic_block_head[i]);
1.1.1.2 root 377: /* TEMP1 is used to avoid a bug in Sequent's compiler. */
378: register int temp1;
1.1 root 379: while (insn && GET_CODE (insn) == NOTE)
380: insn = PREV_INSN (insn);
1.1.1.2 root 381: temp1 = insn && GET_CODE (insn) != BARRIER;
382: basic_block_drops_in[i] = temp1;
1.1 root 383: }
384: }
385:
386: /* Now find which basic blocks can actually be reached
387: and put all jump insns' LABEL_REFS onto the ref-chains
388: of their target labels. */
389:
390: if (n_basic_blocks > 0)
391: {
392: register char *block_live = (char *) alloca (n_basic_blocks);
393: register char *block_marked = (char *) alloca (n_basic_blocks);
394: int something_marked = 1;
395:
396: /* Initialize with just block 0 reachable and no blocks marked. */
397:
398: bzero (block_live, n_basic_blocks);
399: bzero (block_marked, n_basic_blocks);
400: block_live[0] = 1;
401: block_live_static = block_live;
402:
403: /* Pass over all blocks, marking each block that is reachable
404: and has not yet been marked.
405: Keep doing this until, in one pass, no blocks have been marked.
406: Then blocks_live and blocks_marked are identical and correct.
407: In addition, all jumps actually reachable have been marked. */
408:
409: while (something_marked)
410: {
411: something_marked = 0;
412: for (i = 0; i < n_basic_blocks; i++)
413: if (block_live[i] && !block_marked[i])
414: {
415: block_marked[i] = 1;
416: something_marked = 1;
417: if (i + 1 < n_basic_blocks && basic_block_drops_in[i + 1])
418: block_live[i + 1] = 1;
419: insn = basic_block_end[i];
420: if (GET_CODE (insn) == JUMP_INSN)
421: mark_label_ref (PATTERN (insn), insn, 0);
422: }
423: }
424:
425: /* Now delete the code for any basic blocks that can't be reached.
426: They can occur because jump_optimize does not recognize
427: unreachable loops as unreachable. */
428:
429: for (i = 0; i < n_basic_blocks; i++)
430: if (!block_live[i])
431: {
432: insn = basic_block_head[i];
433: while (1)
434: {
1.1.1.2 root 435: if (GET_CODE (insn) == BARRIER)
436: abort ();
1.1 root 437: if (GET_CODE (insn) != NOTE)
438: {
439: PUT_CODE (insn, NOTE);
440: NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED;
441: NOTE_SOURCE_FILE (insn) = 0;
442: }
443: if (insn == basic_block_end[i])
1.1.1.2 root 444: {
445: /* BARRIERs are between basic blocks, not part of one.
446: Delete a BARRIER if the preceding jump is deleted.
447: We cannot alter a BARRIER into a NOTE
448: because it is too short; but we can really delete
449: it because it is not part of a basic block. */
450: if (NEXT_INSN (insn) != 0
451: && GET_CODE (NEXT_INSN (insn)) == BARRIER)
452: delete_insn (NEXT_INSN (insn));
453: break;
454: }
1.1 root 455: insn = NEXT_INSN (insn);
456: }
457: /* Each time we delete some basic blocks,
458: see if there is a jump around them that is
459: being turned into a no-op. If so, delete it. */
460:
461: if (block_live[i - 1])
462: {
463: register int j;
464: for (j = i; j < n_basic_blocks; j++)
465: if (block_live[j])
466: {
1.1.1.6 root 467: rtx label;
1.1 root 468: insn = basic_block_end[i - 1];
469: if (GET_CODE (insn) == JUMP_INSN
1.1.1.6 root 470: /* An unconditional jump is the only possibility
471: we must check for, since a conditional one
472: would make these blocks live. */
473: && simplejump_p (insn)
474: && (label = XEXP (SET_SRC (PATTERN (insn)), 0), 1)
475: && INSN_UID (label) != 0
476: && BLOCK_NUM (label) == j)
1.1 root 477: {
478: PUT_CODE (insn, NOTE);
479: NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED;
480: NOTE_SOURCE_FILE (insn) = 0;
1.1.1.2 root 481: if (GET_CODE (NEXT_INSN (insn)) != BARRIER)
482: abort ();
483: delete_insn (NEXT_INSN (insn));
1.1 root 484: }
485: break;
486: }
487: }
488: }
489: }
490: }
491:
492: /* Check expression X for label references;
493: if one is found, add INSN to the label's chain of references.
494:
495: CHECKDUP means check for and avoid creating duplicate references
496: from the same insn. Such duplicates do no serious harm but
497: can slow life analysis. CHECKDUP is set only when duplicates
498: are likely. */
499:
500: static void
501: mark_label_ref (x, insn, checkdup)
502: rtx x, insn;
503: int checkdup;
504: {
505: register RTX_CODE code = GET_CODE (x);
506: register int i;
507: register char *fmt;
508:
509: if (code == LABEL_REF)
510: {
511: register rtx label = XEXP (x, 0);
512: register rtx y;
513: if (GET_CODE (label) != CODE_LABEL)
1.1.1.4 root 514: abort ();
1.1.1.2 root 515: /* If the label was never emitted, this insn is junk,
516: but avoid a crash trying to refer to BLOCK_NUM (label).
517: This can happen as a result of a syntax error
518: and a diagnostic has already been printed. */
519: if (INSN_UID (label) == 0)
520: return;
1.1 root 521: CONTAINING_INSN (x) = insn;
522: /* if CHECKDUP is set, check for duplicate ref from same insn
523: and don't insert. */
524: if (checkdup)
525: for (y = LABEL_REFS (label); y != label; y = LABEL_NEXTREF (y))
526: if (CONTAINING_INSN (y) == insn)
527: return;
528: LABEL_NEXTREF (x) = LABEL_REFS (label);
529: LABEL_REFS (label) = x;
530: block_live_static[BLOCK_NUM (label)] = 1;
531: return;
532: }
533:
534: fmt = GET_RTX_FORMAT (code);
535: for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
536: {
537: if (fmt[i] == 'e')
538: mark_label_ref (XEXP (x, i), insn, 0);
539: if (fmt[i] == 'E')
540: {
541: register int j;
542: for (j = 0; j < XVECLEN (x, i); j++)
543: mark_label_ref (XVECEXP (x, i, j), insn, 1);
544: }
545: }
546: }
547:
548: /* Determine the which registers are live at the start of each
549: basic block of the function whose first insn is F.
550: NREGS is the number of registers used in F.
551: We allocate the vector basic_block_live_at_start
552: and the regsets that it points to, and fill them with the data.
553: regset_size and regset_bytes are also set here. */
554:
555: static void
556: life_analysis (f, nregs)
557: rtx f;
558: int nregs;
559: {
560: register regset tem;
561: int first_pass;
562: int changed;
563: /* For each basic block, a bitmask of regs
564: live on exit from the block. */
565: regset *basic_block_live_at_end;
566: /* For each basic block, a bitmask of regs
567: live on entry to a successor-block of this block.
568: If this does not match basic_block_live_at_end,
569: that must be updated, and the block must be rescanned. */
570: regset *basic_block_new_live_at_end;
571: /* For each basic block, a bitmask of regs
572: whose liveness at the end of the basic block
573: can make a difference in which regs are live on entry to the block.
574: These are the regs that are set within the basic block,
575: possibly excluding those that are used after they are set. */
576: regset *basic_block_significant;
577: register int i;
1.1.1.2 root 578: rtx insn;
1.1 root 579:
580: max_regno = nregs;
581:
582: bzero (regs_ever_live, sizeof regs_ever_live);
583:
584: /* Allocate and zero out many data structures
585: that will record the data from lifetime analysis. */
586:
587: allocate_for_life_analysis ();
588:
589: reg_next_use = (rtx *) alloca (nregs * sizeof (rtx));
590: bzero (reg_next_use, nregs * sizeof (rtx));
591:
592: /* Set up several regset-vectors used internally within this function.
593: Their meanings are documented above, with their declarations. */
594:
595: basic_block_live_at_end = (regset *) alloca (n_basic_blocks * sizeof (regset));
596: tem = (regset) alloca (n_basic_blocks * regset_bytes);
597: bzero (tem, n_basic_blocks * regset_bytes);
598: init_regset_vector (basic_block_live_at_end, tem, n_basic_blocks, regset_bytes);
599:
600: basic_block_new_live_at_end = (regset *) alloca (n_basic_blocks * sizeof (regset));
601: tem = (regset) alloca (n_basic_blocks * regset_bytes);
602: bzero (tem, n_basic_blocks * regset_bytes);
603: init_regset_vector (basic_block_new_live_at_end, tem, n_basic_blocks, regset_bytes);
604:
605: basic_block_significant = (regset *) alloca (n_basic_blocks * sizeof (regset));
606: tem = (regset) alloca (n_basic_blocks * regset_bytes);
607: bzero (tem, n_basic_blocks * regset_bytes);
608: init_regset_vector (basic_block_significant, tem, n_basic_blocks, regset_bytes);
609:
1.1.1.4 root 610: /* Record which insns refer to any volatile memory
1.1.1.9 ! root 611: or for any reason can't be deleted just because they are dead stores.
! 612: Also, delete any insns that copy a register to itself. */
1.1.1.2 root 613:
614: for (insn = f; insn; insn = NEXT_INSN (insn))
1.1.1.4 root 615: {
616: enum rtx_code code1 = GET_CODE (insn);
617: if (code1 == CALL_INSN)
618: INSN_VOLATILE (insn) = 1;
619: else if (code1 == INSN || code1 == JUMP_INSN)
620: {
1.1.1.9 ! root 621: if (GET_CODE (PATTERN (insn)) == SET
! 622: && GET_CODE (SET_DEST (PATTERN (insn))) == REG
! 623: && GET_CODE (SET_SRC (PATTERN (insn))) == REG
! 624: && REGNO (SET_DEST (PATTERN (insn))) ==
! 625: REGNO (SET_SRC (PATTERN (insn))))
! 626: {
! 627: PUT_CODE (insn, NOTE);
! 628: NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED;
! 629: NOTE_SOURCE_FILE (insn) = 0;
! 630: }
! 631: else if (GET_CODE (PATTERN (insn)) != USE)
1.1.1.4 root 632: INSN_VOLATILE (insn) = volatile_refs_p (PATTERN (insn));
633: }
1.1.1.6 root 634: /* A SET that makes space on the stack cannot be dead.
635: Even if this function never uses this stack pointer value,
636: signal handlers do! */
637: else if (code1 == INSN && GET_CODE (PATTERN (insn)) == SET
638: && SET_DEST (PATTERN (insn)) == stack_pointer_rtx
639: #ifdef STACK_GROWS_DOWNWARD
640: && GET_CODE (SET_SRC (PATTERN (insn))) == MINUS
641: #else
642: && GET_CODE (SET_SRC (PATTERN (insn))) == PLUS
643: #endif
644: && XEXP (SET_SRC (PATTERN (insn)), 0) == stack_pointer_rtx)
645: INSN_VOLATILE (insn) = 1;
1.1.1.4 root 646: }
1.1.1.2 root 647:
648: if (n_basic_blocks > 0)
649: #ifdef EXIT_IGNORE_STACK
650: if (! (EXIT_IGNORE_STACK) || ! frame_pointer_needed)
651: #endif
652: {
653: /* If exiting needs the right stack value,
654: consider the stack pointer live at the end of the function. */
655: basic_block_live_at_end[n_basic_blocks - 1]
656: [STACK_POINTER_REGNUM / REGSET_ELT_BITS]
657: |= 1 << (STACK_POINTER_REGNUM % REGSET_ELT_BITS);
658: basic_block_new_live_at_end[n_basic_blocks - 1]
659: [STACK_POINTER_REGNUM / REGSET_ELT_BITS]
660: |= 1 << (STACK_POINTER_REGNUM % REGSET_ELT_BITS);
661: }
662:
1.1 root 663: /* Propagate life info through the basic blocks
664: around the graph of basic blocks.
665:
666: This is a relaxation process: each time a new register
667: is live at the end of the basic block, we must scan the block
668: to determine which registers are, as a consequence, live at the beginning
669: of that block. These registers must then be marked live at the ends
670: of all the blocks that can transfer control to that block.
671: The process continues until it reaches a fixed point. */
672:
673: first_pass = 1;
674: changed = 1;
675: while (changed)
676: {
677: changed = 0;
678: for (i = n_basic_blocks - 1; i >= 0; i--)
679: {
680: int consider = first_pass;
681: int must_rescan = first_pass;
682: register int j;
683:
684: /* Set CONSIDER if this block needs thinking about at all
685: (that is, if the regs live now at the end of it
686: are not the same as were live at the end of it when
687: we last thought about it).
688: Set must_rescan if it needs to be thought about
689: instruction by instruction (that is, if any additional
690: reg that is live at the end now but was not live there before
691: is one of the significant regs of this basic block). */
692:
693: for (j = 0; j < regset_size; j++)
694: {
695: register int x = basic_block_new_live_at_end[i][j]
696: & ~basic_block_live_at_end[i][j];
697: if (x)
698: consider = 1;
699: if (x & basic_block_significant[i][j])
700: {
701: must_rescan = 1;
702: consider = 1;
703: break;
704: }
705: }
706:
707: if (! consider)
708: continue;
709:
710: /* The live_at_start of this block may be changing,
711: so another pass will be required after this one. */
712: changed = 1;
713:
714: if (! must_rescan)
715: {
716: /* No complete rescan needed;
717: just record those variables newly known live at end
718: as live at start as well. */
719: for (j = 0; j < regset_size; j++)
720: {
721: register int x = basic_block_new_live_at_end[i][j]
722: & ~basic_block_live_at_end[i][j];
723: basic_block_live_at_start[i][j] |= x;
724: basic_block_live_at_end[i][j] |= x;
725: }
726: }
727: else
728: {
729: /* Update the basic_block_live_at_start
730: by propagation backwards through the block. */
731: bcopy (basic_block_new_live_at_end[i],
732: basic_block_live_at_end[i], regset_bytes);
733: bcopy (basic_block_live_at_end[i],
734: basic_block_live_at_start[i], regset_bytes);
735: propagate_block (basic_block_live_at_start[i],
736: basic_block_head[i], basic_block_end[i], 0,
737: first_pass ? basic_block_significant[i] : 0,
738: i);
739: }
740:
741: {
742: register rtx jump, head;
743: /* Update the basic_block_new_live_at_end's of the block
744: that falls through into this one (if any). */
745: head = basic_block_head[i];
746: jump = PREV_INSN (head);
747: if (basic_block_drops_in[i])
748: {
749: register from_block = BLOCK_NUM (jump);
750: register int j;
751: for (j = 0; j < regset_size; j++)
752: basic_block_new_live_at_end[from_block][j]
753: |= basic_block_live_at_start[i][j];
754: }
755: /* Update the basic_block_new_live_at_end's of
756: all the blocks that jump to this one. */
757: if (GET_CODE (head) == CODE_LABEL)
758: for (jump = LABEL_REFS (head);
759: jump != head;
760: jump = LABEL_NEXTREF (jump))
761: {
762: register from_block = BLOCK_NUM (CONTAINING_INSN (jump));
763: register int j;
764: for (j = 0; j < regset_size; j++)
765: basic_block_new_live_at_end[from_block][j]
766: |= basic_block_live_at_start[i][j];
767: }
768: }
769: }
770: first_pass = 0;
771: }
772:
1.1.1.5 root 773: #if 0 /* This seems unnecessary; life at start of function shouldn't
774: mean that the reg is live in more than one basic block. */
775:
1.1.1.2 root 776: /* Process the regs live at the beginning of the function.
777: Mark them as not local to any one basic block. */
778:
779: if (n_basic_blocks > 0)
780: for (i = FIRST_PSEUDO_REGISTER; i < max_regno; i++)
781: if (basic_block_live_at_start[0][i / REGSET_ELT_BITS]
782: & (1 << (i % REGSET_ELT_BITS)))
1.1.1.4 root 783: reg_basic_block[i] = REG_BLOCK_GLOBAL;
1.1.1.5 root 784: #endif
1.1.1.2 root 785:
1.1 root 786: /* Now the life information is accurate.
787: Make one more pass over each basic block
788: to delete dead stores, create autoincrement addressing
789: and record how many times each register is used, is set, or dies.
790:
791: To save time, we operate directly in basic_block_live_at_end[i],
792: thus destroying it (in fact, converting it into a copy of
793: basic_block_live_at_start[i]). This is ok now because
794: basic_block_live_at_end[i] is no longer used past this point. */
795:
796: for (i = 0; i < n_basic_blocks; i++)
797: {
798: propagate_block (basic_block_live_at_end[i],
799: basic_block_head[i], basic_block_end[i], 1, 0, i);
800: }
801: }
802:
803: /* Subroutines of life analysis. */
804:
805: /* Allocate the permanent data structures that represent the results
806: of life analysis. Not static since used also for stupid life analysis. */
807:
808: void
809: allocate_for_life_analysis ()
810: {
811: register int i;
812: register regset tem;
813:
814: regset_size = ((max_regno + REGSET_ELT_BITS - 1) / REGSET_ELT_BITS);
815: regset_bytes = regset_size * sizeof (*(regset)0);
816:
817: reg_n_refs = (short *) oballoc (max_regno * sizeof (short));
818: bzero (reg_n_refs, max_regno * sizeof (short));
819:
820: reg_n_sets = (short *) oballoc (max_regno * sizeof (short));
821: bzero (reg_n_sets, max_regno * sizeof (short));
822:
823: reg_n_deaths = (short *) oballoc (max_regno * sizeof (short));
824: bzero (reg_n_deaths, max_regno * sizeof (short));
825:
826: reg_live_length = (int *) oballoc (max_regno * sizeof (int));
827: bzero (reg_live_length, max_regno * sizeof (int));
828:
829: reg_crosses_call = (char *) oballoc (max_regno);
830: bzero (reg_crosses_call, max_regno);
831:
832: reg_basic_block = (short *) oballoc (max_regno * sizeof (short));
833: for (i = 0; i < max_regno; i++)
1.1.1.4 root 834: reg_basic_block[i] = REG_BLOCK_UNKNOWN;
1.1 root 835:
836: basic_block_live_at_start = (regset *) oballoc (n_basic_blocks * sizeof (regset));
837: tem = (regset) oballoc (n_basic_blocks * regset_bytes);
838: bzero (tem, n_basic_blocks * regset_bytes);
839: init_regset_vector (basic_block_live_at_start, tem, n_basic_blocks, regset_bytes);
1.1.1.2 root 840:
841: regs_live_at_setjmp = (regset) oballoc (regset_bytes);
842: bzero (regs_live_at_setjmp, regset_bytes);
1.1 root 843: }
844:
845: /* Make each element of VECTOR point at a regset,
846: taking the space for all those regsets from SPACE.
847: SPACE is of type regset, but it is really as long as NELTS regsets.
848: BYTES_PER_ELT is the number of bytes in one regset. */
849:
850: static void
851: init_regset_vector (vector, space, nelts, bytes_per_elt)
852: regset *vector;
853: regset space;
854: int nelts;
855: int bytes_per_elt;
856: {
857: register int i;
858: register regset p = space;
859:
860: for (i = 0; i < nelts; i++)
861: {
862: vector[i] = p;
863: p += bytes_per_elt / sizeof (*p);
864: }
865: }
866:
867: /* Compute the registers live at the beginning of a basic block
868: from those live at the end.
869:
870: When called, OLD contains those live at the end.
871: On return, it contains those live at the beginning.
872: FIRST and LAST are the first and last insns of the basic block.
873:
874: FINAL is nonzero if we are doing the final pass which is not
875: for computing the life info (since that has already been done)
876: but for acting on it. On this pass, we delete dead stores,
877: set up the logical links and dead-variables lists of instructions,
878: and merge instructions for autoincrement and autodecrement addresses.
879:
880: SIGNIFICANT is nonzero only the first time for each basic block.
881: If it is nonzero, it points to a regset in which we store
882: a 1 for each register that is set within the block.
883:
884: BNUM is the number of the basic block. */
885:
886: static void
887: propagate_block (old, first, last, final, significant, bnum)
888: register regset old;
889: rtx first;
890: rtx last;
891: int final;
892: regset significant;
893: int bnum;
894: {
895: register rtx insn;
896: rtx prev;
897: regset live;
898: regset dead;
899:
900: /* The following variables are used only if FINAL is nonzero. */
901: /* This vector gets one element for each reg that has been live
902: at any point in the basic block that has been scanned so far.
903: SOMETIMES_MAX says how many elements are in use so far.
904: In each element, OFFSET is the byte-number within a regset
905: for the register described by the element, and BIT is a mask
906: for that register's bit within the byte. */
907: register struct foo { short offset; short bit; } *regs_sometimes_live;
908: int sometimes_max = 0;
909: /* This regset has 1 for each reg that we have seen live so far.
910: It and REGS_SOMETIMES_LIVE are updated together. */
911: regset maxlive;
912:
913: loop_depth = basic_block_loop_depth[bnum];
914:
915: dead = (regset) alloca (regset_bytes);
916: live = (regset) alloca (regset_bytes);
917:
918: if (final)
919: {
920: register int i, offset, bit;
921:
922: maxlive = (regset) alloca (regset_bytes);
923: bcopy (old, maxlive, regset_bytes);
924: regs_sometimes_live
925: = (struct foo *) alloca (max_regno * sizeof (struct foo));
926:
927: /* Process the regs live at the end of the block.
928: Enter them in MAXLIVE and REGS_SOMETIMES_LIVE.
929: Also mark them as not local to any one basic block. */
930:
931: for (offset = 0, i = 0; offset < regset_size; offset++)
932: for (bit = 1; bit; bit <<= 1, i++)
933: {
934: if (i == max_regno)
935: break;
936: if (old[offset] & bit)
937: {
1.1.1.4 root 938: reg_basic_block[i] = REG_BLOCK_GLOBAL;
1.1 root 939: regs_sometimes_live[sometimes_max].offset = offset;
940: regs_sometimes_live[sometimes_max].bit = i % REGSET_ELT_BITS;
941: sometimes_max++;
942: }
943: }
944: }
945:
946: /* Scan the block an insn at a time from end to beginning. */
947:
948: for (insn = last; ; insn = prev)
949: {
950: prev = PREV_INSN (insn);
951:
1.1.1.2 root 952: /* If this is a call to `setjmp' et al,
953: warn if any non-volatile datum is live. */
954:
955: if (final && GET_CODE (insn) == NOTE
956: && NOTE_LINE_NUMBER (insn) == NOTE_INSN_SETJMP)
957: {
958: int i;
959: for (i = 0; i < regset_size; i++)
960: regs_live_at_setjmp[i] |= old[i];
1.1 root 961: }
962:
963: /* Update the life-status of regs for this insn.
964: First DEAD gets which regs are set in this insn
965: then LIVE gets which regs are used in this insn.
966: Then the regs live before the insn
967: are those live after, with DEAD regs turned off,
968: and then LIVE regs turned on. */
969:
970: if (GET_CODE (insn) == INSN
971: || GET_CODE (insn) == JUMP_INSN
972: || GET_CODE (insn) == CALL_INSN)
973: {
974: register int i;
1.1.1.2 root 975: rtx note = find_reg_note (insn, REG_RETVAL, 0);
976:
1.1 root 977: /* If an instruction consists of just dead store(s) on final pass,
978: "delete" it by turning it into a NOTE of type NOTE_INSN_DELETED.
979: We could really delete it with delete_insn, but that
980: can cause trouble for first or last insn in a basic block. */
1.1.1.2 root 981: if (final && insn_dead_p (PATTERN (insn), old, 1)
982: /* Don't delete something that refers to volatile storage! */
983: && ! INSN_VOLATILE (insn))
1.1 root 984: {
985: PUT_CODE (insn, NOTE);
986: NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED;
987: NOTE_SOURCE_FILE (insn) = 0;
1.1.1.2 root 988: /* If this insn is copying the return value from a library call,
989: delete the entire library call. */
990: if (note)
991: {
992: rtx first = XEXP (note, 0);
993: rtx prev = insn;
1.1.1.9 ! root 994: while (INSN_DELETED_P (first))
1.1.1.2 root 995: first = NEXT_INSN (first);
996: while (prev != first)
997: {
998: prev = PREV_INSN (prev);
999: PUT_CODE (prev, NOTE);
1000: NOTE_LINE_NUMBER (prev) = NOTE_INSN_DELETED;
1001: NOTE_SOURCE_FILE (prev) = 0;
1002: }
1003: }
1.1 root 1004: goto flushed;
1005: }
1.1.1.2 root 1006:
1007: for (i = 0; i < regset_size; i++)
1.1 root 1008: {
1.1.1.2 root 1009: dead[i] = 0; /* Faster than bzero here */
1010: live[i] = 0; /* since regset_size is usually small */
1011: }
1.1 root 1012:
1.1.1.2 root 1013: /* See if this is an increment or decrement that can be
1014: merged into a following memory address. */
1015: #ifdef AUTO_INC_DEC
1016: {
1017: register rtx x = PATTERN (insn);
1018: /* Does this instruction increment or decrement a register? */
1019: if (final && GET_CODE (x) == SET
1020: && GET_CODE (SET_DEST (x)) == REG
1021: && (GET_CODE (SET_SRC (x)) == PLUS
1022: || GET_CODE (SET_SRC (x)) == MINUS)
1023: && XEXP (SET_SRC (x), 0) == SET_DEST (x)
1024: && GET_CODE (XEXP (SET_SRC (x), 1)) == CONST_INT
1025: /* Ok, look for a following memory ref we can combine with.
1026: If one is found, change the memory ref to a PRE_INC
1027: or PRE_DEC, cancel this insn, and return 1.
1028: Return 0 if nothing has been done. */
1029: && try_pre_increment_1 (insn))
1030: goto flushed;
1031: }
1032: #endif /* AUTO_INC_DEC */
1.1 root 1033:
1.1.1.2 root 1034: /* If this is not the final pass, and this insn is copying the
1035: value of a library call and it's dead, don't scan the
1036: insns that perform the library call, so that the call's
1037: arguments are not marked live. */
1038: if (note && insn_dead_p (PATTERN (insn), old, 1))
1.1.1.3 root 1039: {
1.1.1.4 root 1040: /* Mark the dest reg as `significant'. */
1041: mark_set_regs (old, dead, PATTERN (insn), 0, significant);
1042:
1.1.1.3 root 1043: insn = XEXP (note, 0);
1044: prev = PREV_INSN (insn);
1045: }
1.1.1.9 ! root 1046: else if (GET_CODE (PATTERN (insn)) == SET
! 1047: && SET_DEST (PATTERN (insn)) == stack_pointer_rtx
1.1.1.4 root 1048: && GET_CODE (SET_SRC (PATTERN (insn))) == PLUS
1049: && XEXP (SET_SRC (PATTERN (insn)), 0) == stack_pointer_rtx
1050: && GET_CODE (XEXP (SET_SRC (PATTERN (insn)), 1)) == CONST_INT)
1051: /* These insns, if not dead stores, have no effect on life. */
1052: ;
1.1.1.2 root 1053: else
1054: {
1055: /* LIVE gets the regs used in INSN; DEAD gets those set by it. */
1.1 root 1056: mark_set_regs (old, dead, PATTERN (insn), final ? insn : 0,
1057: significant);
1.1.1.2 root 1058: mark_used_regs (old, live, PATTERN (insn), final, insn);
1.1 root 1059:
1060: /* Update OLD for the registers used or set. */
1061: for (i = 0; i < regset_size; i++)
1062: {
1063: old[i] &= ~dead[i];
1064: old[i] |= live[i];
1065: }
1066:
1.1.1.2 root 1067: if (GET_CODE (insn) == CALL_INSN)
1068: {
1069: register int i;
1070:
1071: /* Each call clobbers all call-clobbered regs.
1072: Note that the function-value reg is one of these, and
1073: mark_set_regs has already had a chance to handle it. */
1074: for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
1075: if (call_used_regs[i])
1.1.1.9 ! root 1076: dead[i / REGSET_ELT_BITS] |=
! 1077: (1 << (i % REGSET_ELT_BITS));
1.1.1.2 root 1078:
1079: /* The stack ptr is used (honorarily) by a CALL insn. */
1.1.1.9 ! root 1080: live[STACK_POINTER_REGNUM / REGSET_ELT_BITS]
1.1.1.2 root 1081: |= (1 << (STACK_POINTER_REGNUM % REGSET_ELT_BITS));
1.1.1.9 ! root 1082: }
1.1.1.2 root 1083:
1.1.1.9 ! root 1084: /* Update OLD for the registers used or set. */
! 1085: for (i = 0; i < regset_size; i++)
! 1086: {
! 1087: old[i] &= ~dead[i];
! 1088: old[i] |= live[i];
! 1089: }
! 1090:
! 1091: if (GET_CODE (insn) == CALL_INSN && final)
! 1092: {
! 1093: /* Any regs live at the time of a call instruction
! 1094: must not go in a register clobbered by calls.
! 1095: Find all regs now live and record this for them. */
! 1096:
! 1097: register struct foo *p = regs_sometimes_live;
! 1098:
! 1099: for (i = 0; i < sometimes_max; i++, p++)
! 1100: if (old[p->offset] & (1 << p->bit))
! 1101: reg_crosses_call[p->offset * REGSET_ELT_BITS + p->bit] = 1;
1.1.1.2 root 1102: }
1103: }
1104:
1105: /* On final pass, add any additional sometimes-live regs
1106: into MAXLIVE and REGS_SOMETIMES_LIVE.
1107: Also update counts of how many insns each reg is live at. */
1.1 root 1108:
1.1.1.2 root 1109: if (final)
1110: {
1111: for (i = 0; i < regset_size; i++)
1.1 root 1112: {
1.1.1.2 root 1113: register int diff = live[i] & ~maxlive[i];
1.1 root 1114:
1.1.1.2 root 1115: if (diff)
1116: {
1117: register int regno;
1118: maxlive[i] |= diff;
1119: for (regno = 0; diff && regno < REGSET_ELT_BITS; regno++)
1120: if (diff & (1 << regno))
1121: {
1122: regs_sometimes_live[sometimes_max].offset = i;
1123: regs_sometimes_live[sometimes_max].bit = regno;
1124: diff &= ~ (1 << regno);
1125: sometimes_max++;
1126: }
1127: }
1128: }
1.1 root 1129:
1.1.1.2 root 1130: {
1131: register struct foo *p = regs_sometimes_live;
1132: for (i = 0; i < sometimes_max; i++, p++)
1.1 root 1133: {
1.1.1.2 root 1134: if (old[p->offset] & (1 << p->bit))
1135: reg_live_length[p->offset * REGSET_ELT_BITS + p->bit]++;
1.1 root 1136: }
1.1.1.2 root 1137: }
1.1 root 1138: }
1139: }
1.1.1.2 root 1140: flushed: ;
1.1 root 1141: if (insn == first)
1142: break;
1143: }
1144: }
1145:
1146: /* Return 1 if X (the body of an insn, or part of it) is just dead stores
1147: (SET expressions whose destinations are registers dead after the insn).
1148: NEEDED is the regset that says which regs are alive after the insn. */
1149:
1150: static int
1.1.1.2 root 1151: insn_dead_p (x, needed, strict_low_ok)
1.1 root 1152: rtx x;
1153: regset needed;
1.1.1.2 root 1154: int strict_low_ok;
1.1 root 1155: {
1156: register RTX_CODE code = GET_CODE (x);
1.1.1.2 root 1157: #if 0
1.1 root 1158: /* Make sure insns to set the stack pointer are never deleted. */
1159: needed[STACK_POINTER_REGNUM / REGSET_ELT_BITS]
1160: |= 1 << (STACK_POINTER_REGNUM % REGSET_ELT_BITS);
1.1.1.2 root 1161: #endif
1162:
1163: /* If setting something that's a reg or part of one,
1164: see if that register's altered value will be live. */
1165:
1166: if (code == SET)
1.1 root 1167: {
1.1.1.2 root 1168: register rtx r = SET_DEST (x);
1169: /* A SET that is a subroutine call cannot be dead. */
1170: if (GET_CODE (SET_SRC (x)) == CALL)
1171: return 0;
1172: while (GET_CODE (r) == SUBREG
1173: || (strict_low_ok && GET_CODE (r) == STRICT_LOW_PART)
1174: || GET_CODE (r) == ZERO_EXTRACT
1175: || GET_CODE (r) == SIGN_EXTRACT)
1176: r = SUBREG_REG (r);
1177: if (GET_CODE (r) == REG)
1178: {
1179: register int regno = REGNO (r);
1180: register int offset = regno / REGSET_ELT_BITS;
1181: register int bit = 1 << (regno % REGSET_ELT_BITS);
1182: return (needed[offset] & bit) == 0;
1183: }
1.1 root 1184: }
1.1.1.2 root 1185: /* If performing several activities,
1186: insn is dead if each activity is individually dead.
1187: Also, CLOBBERs and USEs can be ignored; a CLOBBER or USE
1188: that's inside a PARALLEL doesn't make the insn worth keeping. */
1189: else if (code == PARALLEL)
1.1 root 1190: {
1191: register int i = XVECLEN (x, 0);
1192: for (i--; i >= 0; i--)
1.1.1.2 root 1193: {
1194: rtx elt = XVECEXP (x, 0, i);
1195: if (!insn_dead_p (elt, needed, strict_low_ok)
1196: && GET_CODE (elt) != CLOBBER
1197: && GET_CODE (elt) != USE)
1198: return 0;
1199: }
1.1 root 1200: return 1;
1201: }
1.1.1.2 root 1202: /* We do not check CLOBBER or USE here.
1203: An insn consisting of just a CLOBBER or just a USE
1204: should not be deleted. */
1.1 root 1205: return 0;
1206: }
1207:
1.1.1.2 root 1208: /* Return 1 if register REGNO was used before it was set.
1209: In other words, if it is live at function entry. */
1.1 root 1210:
1.1.1.2 root 1211: int
1212: regno_uninitialized (regno)
1.1 root 1213: int regno;
1214: {
1.1.1.2 root 1215: return (basic_block_live_at_start[0][regno / REGSET_ELT_BITS]
1216: & (1 << (regno % REGSET_ELT_BITS)));
1217: }
1218:
1219: /* 1 if register REGNO was alive at a place where `setjmp' was called
1220: and was set more than once. Such regs may be clobbered by `longjmp'. */
1221:
1222: int
1223: regno_clobbered_at_setjmp (regno)
1224: int regno;
1225: {
1226: return (reg_n_sets[regno] > 1
1227: && (regs_live_at_setjmp[regno / REGSET_ELT_BITS]
1228: & (1 << (regno % REGSET_ELT_BITS))));
1.1 root 1229: }
1230:
1231: /* Process the registers that are set within X.
1232: Their bits are set to 1 in the regset DEAD,
1233: because they are dead prior to this insn.
1234:
1235: If INSN is nonzero, it is the insn being processed
1236: and the fact that it is nonzero implies this is the FINAL pass
1237: in propagate_block. In this case, various info about register
1238: usage is stored, LOG_LINKS fields of insns are set up. */
1239:
1240: static void mark_set_1 ();
1241:
1242: static void
1243: mark_set_regs (needed, dead, x, insn, significant)
1244: regset needed;
1245: regset dead;
1246: rtx x;
1247: rtx insn;
1248: regset significant;
1249: {
1250: register RTX_CODE code = GET_CODE (x);
1251:
1252: if (code == SET || code == CLOBBER)
1253: mark_set_1 (needed, dead, x, insn, significant);
1254: else if (code == PARALLEL)
1255: {
1256: register int i;
1257: for (i = XVECLEN (x, 0) - 1; i >= 0; i--)
1258: {
1259: code = GET_CODE (XVECEXP (x, 0, i));
1260: if (code == SET || code == CLOBBER)
1261: mark_set_1 (needed, dead, XVECEXP (x, 0, i), insn, significant);
1262: }
1263: }
1264: }
1265:
1266: /* Process a single SET rtx, X. */
1267:
1268: static void
1269: mark_set_1 (needed, dead, x, insn, significant)
1270: regset needed;
1271: regset dead;
1272: rtx x;
1273: rtx insn;
1274: regset significant;
1275: {
1276: register int regno;
1277: register rtx reg = SET_DEST (x);
1278:
1.1.1.2 root 1279: if (reg == 0)
1280: return;
1281:
1.1 root 1282: if (GET_CODE (reg) == SUBREG)
1283: {
1284: /* Modifying just one hardware register
1285: of a multi-register value does not count as "setting"
1286: for live-dead analysis. Parts of the previous value
1287: might still be significant below this insn. */
1288: if (REG_SIZE (SUBREG_REG (reg)) > REG_SIZE (reg))
1289: return;
1290:
1291: reg = SUBREG_REG (reg);
1292: }
1293:
1294: if (GET_CODE (reg) == REG
1295: && (regno = REGNO (reg), regno != FRAME_POINTER_REGNUM)
1.1.1.2 root 1296: && regno != ARG_POINTER_REGNUM)
1297: /* && regno != STACK_POINTER_REGNUM) -- let's try without this. */
1.1 root 1298: {
1299: register int offset = regno / REGSET_ELT_BITS;
1300: register int bit = 1 << (regno % REGSET_ELT_BITS);
1.1.1.2 root 1301: int is_needed = 0;
1302:
1.1 root 1303: /* Mark the reg being set as dead before this insn. */
1304: dead[offset] |= bit;
1305: /* Mark it as a significant register for this basic block. */
1306: if (significant)
1307: significant[offset] |= bit;
1.1.1.2 root 1308: /* A hard reg in a wide mode may really be multiple registers.
1309: If so, mark all of them just like the first. */
1310: if (regno < FIRST_PSEUDO_REGISTER)
1311: {
1.1.1.4 root 1312: int n;
1313:
1314: /* Nothing below is needed for the stack pointer; get out asap.
1315: Eg, log links aren't needed, since combine won't use them. */
1316: if (regno == STACK_POINTER_REGNUM)
1317: return;
1318:
1319: n = HARD_REGNO_NREGS (regno, GET_MODE (reg));
1.1.1.2 root 1320: while (--n > 0)
1321: {
1322: dead[(regno + n) / REGSET_ELT_BITS]
1323: |= 1 << ((regno + n) % REGSET_ELT_BITS);
1324: if (significant)
1325: significant[(regno + n) / REGSET_ELT_BITS]
1326: |= 1 << ((regno + n) % REGSET_ELT_BITS);
1327: is_needed |= (needed[(regno + n) / REGSET_ELT_BITS]
1328: & 1 << ((regno + n) % REGSET_ELT_BITS));
1329: }
1330: }
1.1 root 1331: /* Additional data to record if this is the final pass. */
1332: if (insn)
1333: {
1334: register rtx y = reg_next_use[regno];
1335: register int blocknum = BLOCK_NUM (insn);
1336:
1.1.1.9 ! root 1337: /* If this is a hard reg, record this function uses the reg.
! 1338: `combine.c' will get confused if LOG_LINKs are made
! 1339: for hard regs. */
1.1 root 1340:
1341: if (regno < FIRST_PSEUDO_REGISTER)
1342: {
1343: register int i;
1344: i = HARD_REGNO_NREGS (regno, GET_MODE (reg));
1.1.1.8 root 1345: if (i == 0)
1346: i = 1;
1.1 root 1347: do
1348: regs_ever_live[regno + --i] = 1;
1349: while (i > 0);
1.1.1.4 root 1350:
1351: if (! ((needed[offset] & bit) || is_needed))
1352: {
1353: /* Note that dead stores have already been deleted if poss.
1354: If we get here, we have found a dead store that cannot
1355: be eliminated (because the insn does something useful).
1356: Indicate this by marking the reg set as dying here. */
1357: REG_NOTES (insn)
1358: = gen_rtx (EXPR_LIST, REG_DEAD,
1359: reg, REG_NOTES (insn));
1360: reg_n_deaths[REGNO (reg)]++;
1361: }
1362: return;
1.1 root 1363: }
1364:
1365: /* Keep track of which basic blocks each reg appears in. */
1366:
1.1.1.4 root 1367: if (reg_basic_block[regno] == REG_BLOCK_UNKNOWN)
1.1 root 1368: reg_basic_block[regno] = blocknum;
1369: else if (reg_basic_block[regno] != blocknum)
1.1.1.4 root 1370: reg_basic_block[regno] = REG_BLOCK_GLOBAL;
1.1 root 1371:
1372: /* Count (weighted) references, stores, etc. */
1373: reg_n_refs[regno] += loop_depth;
1374: reg_n_sets[regno]++;
1.1.1.2 root 1375: /* The next use is no longer "next", since a store intervenes. */
1376: reg_next_use[regno] = 0;
1.1 root 1377: /* The insns where a reg is live are normally counted elsewhere,
1378: but we want the count to include the insn where the reg is set,
1379: and the normal counting mechanism would not count it. */
1380: reg_live_length[regno]++;
1.1.1.2 root 1381: if ((needed[offset] & bit) || is_needed)
1.1 root 1382: {
1383: /* Make a logical link from the next following insn
1384: that uses this register, back to this insn.
1385: The following insns have already been processed. */
1386: if (y && (BLOCK_NUM (y) == blocknum))
1387: LOG_LINKS (y)
1388: = gen_rtx (INSN_LIST, VOIDmode, insn, LOG_LINKS (y));
1389: }
1390: else
1391: {
1392: /* Note that dead stores have already been deleted when possible
1393: If we get here, we have found a dead store that cannot
1394: be eliminated (because the same insn does something useful).
1395: Indicate this by marking the reg being set as dying here. */
1396: REG_NOTES (insn)
1397: = gen_rtx (EXPR_LIST, REG_DEAD,
1398: reg, REG_NOTES (insn));
1.1.1.3 root 1399: reg_n_deaths[REGNO (reg)]++;
1.1 root 1400: }
1401: }
1402: }
1403: }
1404:
1405: /* Scan expression X and store a 1-bit in LIVE for each reg it uses.
1406: This is done assuming the registers needed from X
1407: are those that have 1-bits in NEEDED.
1408:
1.1.1.2 root 1409: On the final pass, FINAL is 1. This means try for autoincrement
1410: and count the uses and deaths of each pseudo-reg.
1411:
1412: INSN is the containing instruction. */
1.1 root 1413:
1414: static void
1.1.1.2 root 1415: mark_used_regs (needed, live, x, final, insn)
1.1 root 1416: regset needed;
1417: regset live;
1418: rtx x;
1419: rtx insn;
1.1.1.2 root 1420: int final;
1.1 root 1421: {
1422: register RTX_CODE code;
1423: register int regno;
1424:
1425: retry:
1426: code = GET_CODE (x);
1427: switch (code)
1428: {
1429: case LABEL_REF:
1430: case SYMBOL_REF:
1431: case CONST_INT:
1432: case CONST:
1.1.1.4 root 1433: case CONST_DOUBLE:
1.1 root 1434: case CC0:
1435: case PC:
1436: case CLOBBER:
1.1.1.4 root 1437: case ADDR_VEC:
1438: case ADDR_DIFF_VEC:
1439: case ASM_INPUT:
1.1 root 1440: return;
1441:
1442: #if defined (HAVE_POST_INCREMENT) || defined (HAVE_POST_DECREMENT)
1443: case MEM:
1444: /* Here we detect use of an index register which might
1445: be good for postincrement or postdecrement. */
1.1.1.2 root 1446: if (final)
1.1 root 1447: {
1448: rtx addr = XEXP (x, 0);
1449: register int size = GET_MODE_SIZE (GET_MODE (x));
1450:
1451: if (GET_CODE (addr) == REG)
1452: {
1453: register rtx y;
1454: regno = REGNO (addr);
1455: /* Is the next use an increment that might make auto-increment? */
1456: y = reg_next_use[regno];
1457: if (y && GET_CODE (PATTERN (y)) == SET
1458: && BLOCK_NUM (y) == BLOCK_NUM (insn)
1459: /* Can't add side effects to jumps; if reg is spilled and
1460: reloaded, there's no way to store back the altered value. */
1461: && GET_CODE (insn) != JUMP_INSN
1462: && (y = SET_SRC (PATTERN (y)),
1463: (0
1464: #ifdef HAVE_POST_INCREMENT
1465: || GET_CODE (y) == PLUS
1466: #endif
1467: #ifdef HAVE_POST_DECREMENT
1468: || GET_CODE (y) == MINUS
1469: #endif
1470: )
1471: && XEXP (y, 0) == addr
1472: && GET_CODE (XEXP (y, 1)) == CONST_INT
1.1.1.2 root 1473: && INTVAL (XEXP (y, 1)) == size)
1474: && dead_or_set_p (reg_next_use[regno], addr))
1.1 root 1475: {
1.1.1.2 root 1476: rtx use = find_use_as_address (PATTERN (insn), addr, 0);
1.1 root 1477:
1478: /* Make sure this register appears only once in this insn. */
1479: if (use != 0 && use != (rtx) 1)
1480: {
1481: /* We have found a suitable auto-increment:
1482: do POST_INC around the register here,
1483: and patch out the increment instruction that follows. */
1484: XEXP (x, 0)
1485: = gen_rtx (GET_CODE (y) == PLUS ? POST_INC : POST_DEC,
1486: Pmode, addr);
1487: /* Record that this insn has an implicit side effect. */
1488: REG_NOTES (insn)
1489: = gen_rtx (EXPR_LIST, REG_INC, addr, REG_NOTES (insn));
1490:
1.1.1.2 root 1491: /* Modify the old increment-insn to simply copy
1492: the already-incremented value of our register. */
1.1 root 1493: y = reg_next_use[regno];
1.1.1.2 root 1494: SET_SRC (PATTERN (y)) = addr;
1495:
1496: /* If that makes it a no-op (copying the register
1497: into itself) then change it to a simpler no-op
1498: so it won't appear to be a "use" and a "set"
1499: of this register. */
1500: if (SET_DEST (PATTERN (y)) == addr)
1501: PATTERN (y) = gen_rtx (USE, VOIDmode, const0_rtx);
1502:
1503: /* Count an extra reference to the reg for the increment.
1504: When a reg is incremented.
1.1 root 1505: spilling it is worse, so we want to make that
1506: less likely. */
1507: reg_n_refs[regno] += loop_depth;
1.1.1.2 root 1508: /* Count the increment as a setting of the register,
1509: even though it isn't a SET in rtl. */
1510: reg_n_sets[regno]++;
1.1 root 1511: }
1512: }
1513: }
1514: }
1515: break;
1516: #endif /* HAVE_POST_INCREMENT or HAVE_POST_DECREMENT */
1517:
1518: case REG:
1519: /* See a register other than being set
1520: => mark it as needed. */
1521:
1522: regno = REGNO (x);
1523: if (regno != FRAME_POINTER_REGNUM
1.1.1.2 root 1524: && regno != ARG_POINTER_REGNUM)
1525: /* && regno != STACK_POINTER_REGNUM) -- let's try without this. */
1.1 root 1526: {
1527: register int offset = regno / REGSET_ELT_BITS;
1528: register int bit = 1 << (regno % REGSET_ELT_BITS);
1.1.1.2 root 1529: int is_needed = 0;
1530:
1.1 root 1531: live[offset] |= bit;
1.1.1.2 root 1532: /* A hard reg in a wide mode may really be multiple registers.
1533: If so, mark all of them just like the first. */
1534: if (regno < FIRST_PSEUDO_REGISTER)
1535: {
1.1.1.4 root 1536: int n;
1537:
1538: /* For stack ptr, nothing below here can be necessary,
1539: so waste no more time. */
1540: if (regno == STACK_POINTER_REGNUM)
1541: return;
1542:
1543: n = HARD_REGNO_NREGS (regno, GET_MODE (x));
1.1.1.2 root 1544: while (--n > 0)
1545: {
1546: live[(regno + n) / REGSET_ELT_BITS]
1547: |= 1 << ((regno + n) % REGSET_ELT_BITS);
1548: is_needed |= (needed[(regno + n) / REGSET_ELT_BITS]
1549: & 1 << ((regno + n) % REGSET_ELT_BITS));
1550: }
1551: }
1552: if (final)
1.1 root 1553: {
1554: if (regno < FIRST_PSEUDO_REGISTER)
1555: {
1.1.1.4 root 1556: /* If a hard reg is being used,
1557: record that this function does use it. */
1558:
1.1 root 1559: register int i;
1560: i = HARD_REGNO_NREGS (regno, GET_MODE (x));
1.1.1.8 root 1561: if (i == 0)
1562: i = 1;
1.1 root 1563: do
1564: regs_ever_live[regno + --i] = 1;
1565: while (i > 0);
1566: }
1.1.1.4 root 1567: else
1568: {
1569: /* Keep track of which basic block each reg appears in. */
1.1 root 1570:
1.1.1.4 root 1571: register int blocknum = BLOCK_NUM (insn);
1.1 root 1572:
1.1.1.4 root 1573: if (reg_basic_block[regno] == REG_BLOCK_UNKNOWN)
1574: reg_basic_block[regno] = blocknum;
1575: else if (reg_basic_block[regno] != blocknum)
1576: reg_basic_block[regno] = REG_BLOCK_GLOBAL;
1.1 root 1577:
1.1.1.4 root 1578: /* Record where each reg is used, so when the reg
1579: is set we know the next insn that uses it. */
1.1 root 1580:
1.1.1.4 root 1581: reg_next_use[regno] = insn;
1.1 root 1582:
1.1.1.4 root 1583: /* Count (weighted) number of uses of each reg. */
1.1 root 1584:
1.1.1.4 root 1585: reg_n_refs[regno] += loop_depth;
1586: }
1.1 root 1587: /* Record and count the insns in which a reg dies.
1588: If it is used in this insn and was dead below the insn
1589: then it dies in this insn. */
1590:
1.1.1.2 root 1591: if (!(needed[offset] & bit) && !is_needed
1592: && ! find_regno_note (insn, REG_DEAD, regno))
1.1 root 1593: {
1594: REG_NOTES (insn)
1595: = gen_rtx (EXPR_LIST, REG_DEAD, x, REG_NOTES (insn));
1596: reg_n_deaths[regno]++;
1597: }
1598: }
1599: }
1600: return;
1601:
1602: case SET:
1603: {
1.1.1.2 root 1604: register rtx testreg = SET_DEST (x);
1605: int mark_dest = 0;
1.1 root 1606:
1.1.1.2 root 1607: /* Storing in STRICT_LOW_PART is like storing in a reg
1608: in that this SET might be dead, so ignore it in TESTREG.
1609: but in some other ways it is like using the reg. */
1610: /* Storing in a SUBREG or a bit field is like storing the entire
1611: register in that if the register's value is not used
1612: then this SET is not needed. */
1613: while (GET_CODE (testreg) == STRICT_LOW_PART
1614: || GET_CODE (testreg) == ZERO_EXTRACT
1615: || GET_CODE (testreg) == SIGN_EXTRACT
1616: || GET_CODE (testreg) == SUBREG)
1617: {
1618: /* Modifying a single register in an alternate mode
1619: does not use any of the old value. But these other
1620: ways of storing in a register do use the old value. */
1621: if (GET_CODE (testreg) == SUBREG
1622: && !(REG_SIZE (SUBREG_REG (testreg)) > REG_SIZE (testreg)))
1623: ;
1624: else
1625: mark_dest = 1;
1626:
1627: testreg = XEXP (testreg, 0);
1628: }
1.1 root 1629:
1630: /* If this is a store into a register,
1631: recursively scan the only value being stored,
1632: and only if the register's value is live after this insn.
1633: If the value being computed here would never be used
1634: then the values it uses don't need to be computed either. */
1635:
1.1.1.2 root 1636: if (GET_CODE (testreg) == REG
1637: && (regno = REGNO (testreg), regno != FRAME_POINTER_REGNUM)
1.1.1.7 root 1638: && regno != ARG_POINTER_REGNUM)
1639: #if 0 /* This was added in 1.25, but screws up death notes for hard regs.
1640: It probably isn't really needed anyway. */
1.1.1.6 root 1641: && (regno >= FIRST_PSEUDO_REGISTER
1642: || INSN_VOLATILE (insn)))
1.1.1.7 root 1643: #endif
1.1 root 1644: {
1645: register int offset = regno / REGSET_ELT_BITS;
1646: register int bit = 1 << (regno % REGSET_ELT_BITS);
1.1.1.2 root 1647: if ((needed[offset] & bit)
1648: /* If insn refers to volatile, we mustn't delete it,
1649: so its inputs are all needed. */
1650: || INSN_VOLATILE (insn))
1651: {
1652: mark_used_regs (needed, live, SET_SRC (x), final, insn);
1653: if (mark_dest)
1654: mark_used_regs (needed, live, SET_DEST (x), final, insn);
1655: }
1.1 root 1656: return;
1657: }
1658: }
1659: break;
1660: }
1661:
1662: /* Recursively scan the operands of this expression. */
1663:
1664: {
1665: register char *fmt = GET_RTX_FORMAT (code);
1666: register int i;
1667:
1668: for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
1669: {
1670: if (fmt[i] == 'e')
1671: {
1672: /* Tail recursive case: save a function call level. */
1673: if (i == 0)
1674: {
1675: x = XEXP (x, 0);
1676: goto retry;
1677: }
1.1.1.2 root 1678: mark_used_regs (needed, live, XEXP (x, i), final, insn);
1.1 root 1679: }
1.1.1.4 root 1680: else if (fmt[i] == 'E')
1.1 root 1681: {
1682: register int j;
1683: for (j = 0; j < XVECLEN (x, i); j++)
1.1.1.2 root 1684: mark_used_regs (needed, live, XVECEXP (x, i, j), final, insn);
1.1 root 1685: }
1686: }
1687: }
1688: }
1689:
1.1.1.2 root 1690: #ifdef AUTO_INC_DEC
1.1 root 1691:
1692: static int
1693: try_pre_increment_1 (insn)
1694: rtx insn;
1695: {
1696: /* Find the next use of this reg. If in same basic block,
1697: make it do pre-increment or pre-decrement if appropriate. */
1698: rtx x = PATTERN (insn);
1699: int amount = ((GET_CODE (SET_SRC (x)) == PLUS ? 1 : -1)
1700: * INTVAL (XEXP (SET_SRC (x), 1)));
1701: int regno = REGNO (SET_DEST (x));
1702: rtx y = reg_next_use[regno];
1703: if (y != 0
1704: && BLOCK_NUM (y) == BLOCK_NUM (insn)
1705: && try_pre_increment (y, SET_DEST (PATTERN (insn)),
1706: amount))
1707: {
1708: /* We have found a suitable auto-increment
1709: and already changed insn Y to do it.
1710: So flush this increment-instruction. */
1711: PUT_CODE (insn, NOTE);
1712: NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED;
1713: NOTE_SOURCE_FILE (insn) = 0;
1714: /* Count a reference to this reg for the increment
1715: insn we are deleting. When a reg is incremented.
1716: spilling it is worse, so we want to make that
1717: less likely. */
1718: reg_n_refs[regno] += loop_depth;
1.1.1.2 root 1719: reg_n_sets[regno]++;
1.1 root 1720: return 1;
1721: }
1722: return 0;
1723: }
1724:
1725: /* Try to change INSN so that it does pre-increment or pre-decrement
1726: addressing on register REG in order to add AMOUNT to REG.
1727: AMOUNT is negative for pre-decrement.
1728: Returns 1 if the change could be made.
1729: This checks all about the validity of the result of modifying INSN. */
1730:
1731: static int
1732: try_pre_increment (insn, reg, amount)
1733: rtx insn, reg;
1734: int amount;
1735: {
1736: register rtx use;
1737:
1.1.1.2 root 1738: /* Nonzero if we can try to make a pre-increment or pre-decrement.
1739: For example, addl $4,r1; movl (r1),... can become movl +(r1),... */
1740: int pre_ok = 0;
1741: /* Nonzero if we can try to make a post-increment or post-decrement.
1742: For example, addl $4,r1; movl -4(r1),... can become movl (r1)+,...
1743: It is possible for both PRE_OK and POST_OK to be nonzero if the machine
1744: supports both pre-inc and post-inc, or both pre-dec and post-dec. */
1745: int post_ok = 0;
1746:
1747: /* Nonzero if the opportunity actually requires post-inc or post-dec. */
1748: int do_post = 0;
1749:
1750: /* From the sign of increment, see which possibilities are conceivable
1751: on this target machine. */
1752: #ifdef HAVE_PRE_INCREMENT
1.1 root 1753: if (amount > 0)
1.1.1.2 root 1754: pre_ok = 1;
1.1 root 1755: #endif
1.1.1.2 root 1756: #ifdef HAVE_POST_INCREMENT
1757: if (amount > 0)
1758: post_ok = 1;
1.1 root 1759: #endif
1760:
1.1.1.2 root 1761: #ifdef HAVE_PRE_DECREMENT
1.1 root 1762: if (amount < 0)
1.1.1.2 root 1763: pre_ok = 1;
1764: #endif
1765: #ifdef HAVE_POST_DECREMENT
1766: if (amount < 0)
1767: post_ok = 1;
1.1 root 1768: #endif
1769:
1.1.1.2 root 1770: if (! (pre_ok || post_ok))
1771: return 0;
1772:
1.1 root 1773: /* It is not safe to add a side effect to a jump insn
1774: because if the incremented register is spilled and must be reloaded
1775: there would be no way to store the incremented value back in memory. */
1776:
1777: if (GET_CODE (insn) == JUMP_INSN)
1778: return 0;
1779:
1.1.1.2 root 1780: use = 0;
1781: if (pre_ok)
1782: use = find_use_as_address (PATTERN (insn), reg, 0);
1783: if (post_ok && (use == 0 || use == (rtx) 1))
1784: {
1785: use = find_use_as_address (PATTERN (insn), reg, -amount);
1786: do_post = 1;
1787: }
1.1 root 1788:
1789: if (use == 0 || use == (rtx) 1)
1790: return 0;
1791:
1792: if (GET_MODE_SIZE (GET_MODE (use)) != (amount > 0 ? amount : - amount))
1793: return 0;
1794:
1.1.1.2 root 1795: XEXP (use, 0) = gen_rtx (amount > 0
1796: ? (do_post ? POST_INC : PRE_INC)
1797: : (do_post ? POST_DEC : PRE_DEC),
1.1 root 1798: Pmode, reg);
1799:
1800: /* Record that this insn now has an implicit side effect on X. */
1801: REG_NOTES (insn) = gen_rtx (EXPR_LIST, REG_INC, reg, REG_NOTES (insn));
1802: return 1;
1803: }
1804:
1.1.1.2 root 1805: #endif /* AUTO_INC_DEC */
1806:
1.1 root 1807: /* Find the place in the rtx X where REG is used as a memory address.
1808: Return the MEM rtx that so uses it.
1.1.1.2 root 1809: If PLUSCONST is nonzero, search instead for a memory address equivalent to
1810: (plus REG (const_int PLUSCONST)).
1811:
1812: If such an address does not appear, return 0.
1813: If REG appears more than once, or is used other than in such an address,
1.1 root 1814: return (rtx)1. */
1815:
1816: static rtx
1.1.1.2 root 1817: find_use_as_address (x, reg, plusconst)
1.1 root 1818: register rtx x;
1819: rtx reg;
1.1.1.2 root 1820: int plusconst;
1.1 root 1821: {
1822: enum rtx_code code = GET_CODE (x);
1823: char *fmt = GET_RTX_FORMAT (code);
1824: register int i;
1825: register rtx value = 0;
1826: register rtx tem;
1827:
1.1.1.2 root 1828: if (code == MEM && XEXP (x, 0) == reg && plusconst == 0)
1.1 root 1829: return x;
1830:
1.1.1.2 root 1831: if (code == MEM && GET_CODE (XEXP (x, 0)) == PLUS
1832: && XEXP (XEXP (x, 0), 0) == reg
1833: && GET_CODE (XEXP (XEXP (x, 0), 1)) == CONST_INT
1834: && INTVAL (XEXP (XEXP (x, 0), 1)) == plusconst)
1835: return x;
1836:
1837: if (code == SIGN_EXTRACT || code == ZERO_EXTRACT)
1838: {
1839: /* If REG occurs inside a MEM used in a bit-field reference,
1840: that is unacceptable. */
1841: if (find_use_as_address (XEXP (x, 0), reg, 0) != 0)
1842: return (rtx) 1;
1843: }
1844:
1.1 root 1845: if (x == reg)
1846: return (rtx) 1;
1847:
1848: for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
1849: {
1850: if (fmt[i] == 'e')
1851: {
1.1.1.2 root 1852: tem = find_use_as_address (XEXP (x, i), reg, plusconst);
1.1 root 1853: if (value == 0)
1854: value = tem;
1855: else if (tem != 0)
1856: return (rtx) 1;
1857: }
1858: if (fmt[i] == 'E')
1859: {
1860: register int j;
1861: for (j = XVECLEN (x, i) - 1; j >= 0; j--)
1862: {
1.1.1.2 root 1863: tem = find_use_as_address (XVECEXP (x, i, j), reg, plusconst);
1.1 root 1864: if (value == 0)
1865: value = tem;
1866: else if (tem != 0)
1867: return (rtx) 1;
1868: }
1869: }
1870: }
1871:
1872: return value;
1873: }
1874:
1875: /* Write information about registers and basic blocks into FILE.
1876: This is part of making a debugging dump. */
1877:
1.1.1.2 root 1878: void
1.1 root 1879: dump_flow_info (file)
1880: FILE *file;
1881: {
1882: register int i;
1883: static char *reg_class_names[] = REG_CLASS_NAMES;
1884:
1885: fprintf (file, "%d registers.\n", max_regno);
1886:
1887: for (i = FIRST_PSEUDO_REGISTER; i < max_regno; i++)
1888: if (reg_n_refs[i])
1889: {
1890: enum reg_class class;
1891: fprintf (file, "\nRegister %d used %d times across %d insns",
1892: i, reg_n_refs[i], reg_live_length[i]);
1893: if (reg_basic_block[i] >= 0)
1894: fprintf (file, " in block %d", reg_basic_block[i]);
1895: if (reg_n_deaths[i] != 1)
1896: fprintf (file, "; dies in %d places", reg_n_deaths[i]);
1897: if (reg_crosses_call[i])
1898: fprintf (file, "; crosses calls");
1899: if (PSEUDO_REGNO_BYTES (i) != UNITS_PER_WORD)
1900: fprintf (file, "; %d bytes", PSEUDO_REGNO_BYTES (i));
1901: class = reg_preferred_class (i);
1902: if (class != GENERAL_REGS)
1.1.1.2 root 1903: {
1904: if (reg_preferred_or_nothing (i))
1905: fprintf (file, "; %s or none", reg_class_names[(int) class]);
1906: else
1907: fprintf (file, "; pref %s", reg_class_names[(int) class]);
1908: }
1.1 root 1909: if (REGNO_POINTER_FLAG (i))
1910: fprintf (file, "; pointer");
1911: fprintf (file, ".\n");
1912: }
1913: fprintf (file, "\n%d basic blocks.\n", n_basic_blocks);
1914: for (i = 0; i < n_basic_blocks; i++)
1915: {
1916: register rtx head, jump;
1917: register int regno;
1918: fprintf (file, "\nBasic block %d: first insn %d, last %d.\n",
1919: i,
1920: INSN_UID (basic_block_head[i]),
1921: INSN_UID (basic_block_end[i]));
1922: /* The control flow graph's storage is freed
1923: now when flow_analysis returns.
1924: Don't try to print it if it is gone. */
1925: if (basic_block_drops_in)
1926: {
1927: fprintf (file, "Reached from blocks: ");
1928: head = basic_block_head[i];
1929: if (GET_CODE (head) == CODE_LABEL)
1930: for (jump = LABEL_REFS (head);
1931: jump != head;
1932: jump = LABEL_NEXTREF (jump))
1933: {
1934: register from_block = BLOCK_NUM (CONTAINING_INSN (jump));
1935: fprintf (file, " %d", from_block);
1936: }
1937: if (basic_block_drops_in[i])
1938: fprintf (file, " previous");
1939: }
1940: fprintf (file, "\nRegisters live at start:");
1941: for (regno = 0; regno < max_regno; regno++)
1942: {
1943: register int offset = regno / REGSET_ELT_BITS;
1944: register int bit = 1 << (regno % REGSET_ELT_BITS);
1945: if (basic_block_live_at_start[i][offset] & bit)
1946: fprintf (file, " %d", regno);
1947: }
1948: fprintf (file, "\n");
1949: }
1950: fprintf (file, "\n");
1951: }
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