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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 | \f | |
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 | extern int xmalloc (); | |
125 | extern void free (); | |
126 | ||
127 | /* List of labels that must never be deleted. */ | |
128 | extern rtx forced_labels; | |
129 | ||
130 | /* Get the basic block number of an insn. | |
131 | This info should not be expected to remain available | |
132 | after the end of life_analysis. */ | |
133 | ||
134 | /* This is the limit of the allocated space in the following two arrays. */ | |
135 | ||
136 | static int max_uid_for_flow; | |
137 | ||
138 | #define BLOCK_NUM(INSN) uid_block_number[INSN_UID (INSN)] | |
139 | ||
140 | /* This is where the BLOCK_NUM values are really stored. | |
141 | This is set up by find_basic_blocks and used there and in life_analysis, | |
142 | and then freed. */ | |
143 | ||
144 | static short *uid_block_number; | |
145 | ||
146 | /* INSN_VOLATILE (insn) is 1 if the insn refers to anything volatile. */ | |
147 | ||
148 | #define INSN_VOLATILE(INSN) uid_volatile[INSN_UID (INSN)] | |
149 | static char *uid_volatile; | |
150 | ||
151 | /* Number of basic blocks in the current function. */ | |
152 | ||
153 | int n_basic_blocks; | |
154 | ||
155 | /* Maximum register number used in this function, plus one. */ | |
156 | ||
157 | int max_regno; | |
158 | ||
159 | /* Maximum number of SCRATCH rtx's used in any basic block of this function. */ | |
160 | ||
161 | int max_scratch; | |
162 | ||
163 | /* Number of SCRATCH rtx's in the current block. */ | |
164 | ||
165 | static int num_scratch; | |
166 | ||
167 | /* Indexed by n, gives number of basic block that (REG n) is used in. | |
168 | If the value is REG_BLOCK_GLOBAL (-2), | |
169 | it means (REG n) is used in more than one basic block. | |
170 | REG_BLOCK_UNKNOWN (-1) means it hasn't been seen yet so we don't know. | |
171 | This information remains valid for the rest of the compilation | |
172 | of the current function; it is used to control register allocation. */ | |
173 | ||
174 | short *reg_basic_block; | |
175 | ||
176 | /* Indexed by n, gives number of times (REG n) is used or set, each | |
177 | weighted by its loop-depth. | |
178 | This information remains valid for the rest of the compilation | |
179 | of the current function; it is used to control register allocation. */ | |
180 | ||
181 | int *reg_n_refs; | |
182 | ||
183 | /* Indexed by N, gives number of places register N dies. | |
184 | This information remains valid for the rest of the compilation | |
185 | of the current function; it is used to control register allocation. */ | |
186 | ||
187 | short *reg_n_deaths; | |
188 | ||
189 | /* Indexed by N, gives 1 if that reg is live across any CALL_INSNs. | |
190 | This information remains valid for the rest of the compilation | |
191 | of the current function; it is used to control register allocation. */ | |
192 | ||
193 | int *reg_n_calls_crossed; | |
194 | ||
195 | /* Total number of instructions at which (REG n) is live. | |
196 | The larger this is, the less priority (REG n) gets for | |
197 | allocation in a real register. | |
198 | This information remains valid for the rest of the compilation | |
199 | of the current function; it is used to control register allocation. | |
200 | ||
201 | local-alloc.c may alter this number to change the priority. | |
202 | ||
203 | Negative values are special. | |
204 | -1 is used to mark a pseudo reg which has a constant or memory equivalent | |
205 | and is used infrequently enough that it should not get a hard register. | |
206 | -2 is used to mark a pseudo reg for a parameter, when a frame pointer | |
207 | is not required. global-alloc.c makes an allocno for this but does | |
208 | not try to assign a hard register to it. */ | |
209 | ||
210 | int *reg_live_length; | |
211 | ||
212 | /* Element N is the next insn that uses (hard or pseudo) register number N | |
213 | within the current basic block; or zero, if there is no such insn. | |
214 | This is valid only during the final backward scan in propagate_block. */ | |
215 | ||
216 | static rtx *reg_next_use; | |
217 | ||
218 | /* Size of a regset for the current function, | |
219 | in (1) bytes and (2) elements. */ | |
220 | ||
221 | int regset_bytes; | |
222 | int regset_size; | |
223 | ||
224 | /* Element N is first insn in basic block N. | |
225 | This info lasts until we finish compiling the function. */ | |
226 | ||
227 | rtx *basic_block_head; | |
228 | ||
229 | /* Element N is last insn in basic block N. | |
230 | This info lasts until we finish compiling the function. */ | |
231 | ||
232 | rtx *basic_block_end; | |
233 | ||
234 | /* Element N is a regset describing the registers live | |
235 | at the start of basic block N. | |
236 | This info lasts until we finish compiling the function. */ | |
237 | ||
238 | regset *basic_block_live_at_start; | |
239 | ||
240 | /* Regset of regs live when calls to `setjmp'-like functions happen. */ | |
241 | ||
242 | regset regs_live_at_setjmp; | |
243 | ||
244 | /* List made of EXPR_LIST rtx's which gives pairs of pseudo registers | |
245 | that have to go in the same hard reg. | |
246 | The first two regs in the list are a pair, and the next two | |
247 | are another pair, etc. */ | |
248 | rtx regs_may_share; | |
249 | ||
250 | /* Element N is nonzero if control can drop into basic block N | |
251 | from the preceding basic block. Freed after life_analysis. */ | |
252 | ||
253 | static char *basic_block_drops_in; | |
254 | ||
255 | /* Element N is depth within loops of the last insn in basic block number N. | |
256 | Freed after life_analysis. */ | |
257 | ||
258 | static short *basic_block_loop_depth; | |
259 | ||
260 | /* Element N nonzero if basic block N can actually be reached. | |
261 | Vector exists only during find_basic_blocks. */ | |
262 | ||
263 | static char *block_live_static; | |
264 | ||
265 | /* Depth within loops of basic block being scanned for lifetime analysis, | |
266 | plus one. This is the weight attached to references to registers. */ | |
267 | ||
268 | static int loop_depth; | |
269 | ||
270 | /* During propagate_block, this is non-zero if the value of CC0 is live. */ | |
271 | ||
272 | static int cc0_live; | |
273 | ||
274 | /* During propagate_block, this contains the last MEM stored into. It | |
275 | is used to eliminate consecutive stores to the same location. */ | |
276 | ||
277 | static rtx last_mem_set; | |
278 | ||
279 | /* Set of registers that may be eliminable. These are handled specially | |
280 | in updating regs_ever_live. */ | |
281 | ||
282 | static HARD_REG_SET elim_reg_set; | |
283 | ||
284 | /* Forward declarations */ | |
285 | static void find_basic_blocks (); | |
286 | static void life_analysis (); | |
287 | static void mark_label_ref (); | |
288 | void allocate_for_life_analysis (); /* Used also in stupid_life_analysis */ | |
289 | static void init_regset_vector (); | |
290 | static void propagate_block (); | |
291 | static void mark_set_regs (); | |
292 | static void mark_used_regs (); | |
293 | static int insn_dead_p (); | |
294 | static int libcall_dead_p (); | |
295 | static int try_pre_increment (); | |
296 | static int try_pre_increment_1 (); | |
297 | static rtx find_use_as_address (); | |
298 | void dump_flow_info (); | |
299 | \f | |
300 | /* Find basic blocks of the current function and perform data flow analysis. | |
301 | F is the first insn of the function and NREGS the number of register numbers | |
302 | in use. */ | |
303 | ||
304 | void | |
305 | flow_analysis (f, nregs, file) | |
306 | rtx f; | |
307 | int nregs; | |
308 | FILE *file; | |
309 | { | |
310 | register rtx insn; | |
311 | register int i; | |
312 | ||
313 | #ifdef ELIMINABLE_REGS | |
314 | static struct {int from, to; } eliminables[] = ELIMINABLE_REGS; | |
315 | #endif | |
316 | ||
317 | /* Record which registers will be eliminated. We use this in | |
318 | mark_used_regs. */ | |
319 | ||
320 | CLEAR_HARD_REG_SET (elim_reg_set); | |
321 | ||
322 | #ifdef ELIMINABLE_REGS | |
323 | for (i = 0; i < sizeof eliminables / sizeof eliminables[0]; i++) | |
324 | SET_HARD_REG_BIT (elim_reg_set, eliminables[i].from); | |
325 | #else | |
326 | SET_HARD_REG_BIT (elim_reg_set, FRAME_POINTER_REGNUM); | |
327 | #endif | |
328 | ||
329 | /* Count the basic blocks. Also find maximum insn uid value used. */ | |
330 | ||
331 | { | |
332 | register RTX_CODE prev_code = JUMP_INSN; | |
333 | register RTX_CODE code; | |
334 | ||
335 | max_uid_for_flow = 0; | |
336 | ||
337 | for (insn = f, i = 0; insn; insn = NEXT_INSN (insn)) | |
338 | { | |
339 | code = GET_CODE (insn); | |
340 | if (INSN_UID (insn) > max_uid_for_flow) | |
341 | max_uid_for_flow = INSN_UID (insn); | |
342 | if (code == CODE_LABEL | |
343 | || (prev_code != INSN && prev_code != CALL_INSN | |
344 | && prev_code != CODE_LABEL | |
345 | && GET_RTX_CLASS (code) == 'i')) | |
346 | i++; | |
347 | if (code != NOTE) | |
348 | prev_code = code; | |
349 | } | |
350 | } | |
351 | ||
352 | #ifdef AUTO_INC_DEC | |
353 | /* Leave space for insns we make in some cases for auto-inc. These cases | |
354 | are rare, so we don't need too much space. */ | |
355 | max_uid_for_flow += max_uid_for_flow / 10; | |
356 | #endif | |
357 | ||
358 | /* Allocate some tables that last till end of compiling this function | |
359 | and some needed only in find_basic_blocks and life_analysis. */ | |
360 | ||
361 | n_basic_blocks = i; | |
362 | basic_block_head = (rtx *) oballoc (n_basic_blocks * sizeof (rtx)); | |
363 | basic_block_end = (rtx *) oballoc (n_basic_blocks * sizeof (rtx)); | |
364 | basic_block_drops_in = (char *) alloca (n_basic_blocks); | |
365 | basic_block_loop_depth = (short *) alloca (n_basic_blocks * sizeof (short)); | |
366 | uid_block_number | |
367 | = (short *) alloca ((max_uid_for_flow + 1) * sizeof (short)); | |
368 | uid_volatile = (char *) alloca (max_uid_for_flow + 1); | |
369 | bzero (uid_volatile, max_uid_for_flow + 1); | |
370 | ||
371 | find_basic_blocks (f); | |
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 | \f | |
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 | static void | |
387 | find_basic_blocks (f) | |
388 | rtx f; | |
389 | { | |
390 | register rtx insn; | |
391 | register int i; | |
392 | register char *block_live = (char *) alloca (n_basic_blocks); | |
393 | register char *block_marked = (char *) alloca (n_basic_blocks); | |
394 | /* List of label_refs to all labels whose addresses are taken | |
395 | and used as data. */ | |
396 | rtx label_value_list = 0; | |
397 | ||
398 | block_live_static = block_live; | |
399 | bzero (block_live, n_basic_blocks); | |
400 | bzero (block_marked, n_basic_blocks); | |
401 | ||
402 | /* Initialize with just block 0 reachable and no blocks marked. */ | |
403 | if (n_basic_blocks > 0) | |
404 | block_live[0] = 1; | |
405 | ||
406 | /* Initialize the ref chain of each label to 0. */ | |
407 | /* Record where all the blocks start and end and their depth in loops. */ | |
408 | /* For each insn, record the block it is in. */ | |
409 | /* Also mark as reachable any blocks headed by labels that | |
410 | must not be deleted. */ | |
411 | ||
412 | { | |
413 | register RTX_CODE prev_code = JUMP_INSN; | |
414 | register RTX_CODE code; | |
415 | int depth = 1; | |
416 | ||
417 | for (insn = f, i = -1; insn; insn = NEXT_INSN (insn)) | |
418 | { | |
419 | code = GET_CODE (insn); | |
420 | if (code == NOTE) | |
421 | { | |
422 | if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG) | |
423 | depth++; | |
424 | else if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_END) | |
425 | depth--; | |
426 | } | |
427 | else if (code == CODE_LABEL | |
428 | || (prev_code != INSN && prev_code != CALL_INSN | |
429 | && prev_code != CODE_LABEL | |
430 | && GET_RTX_CLASS (code) == 'i')) | |
431 | { | |
432 | basic_block_head[++i] = insn; | |
433 | basic_block_end[i] = insn; | |
434 | basic_block_loop_depth[i] = depth; | |
435 | if (code == CODE_LABEL) | |
436 | { | |
437 | LABEL_REFS (insn) = insn; | |
438 | /* Any label that cannot be deleted | |
439 | is considered to start a reachable block. */ | |
440 | if (LABEL_PRESERVE_P (insn)) | |
441 | block_live[i] = 1; | |
442 | } | |
443 | } | |
444 | else if (GET_RTX_CLASS (code) == 'i') | |
445 | { | |
446 | basic_block_end[i] = insn; | |
447 | basic_block_loop_depth[i] = depth; | |
448 | } | |
449 | ||
450 | /* Make a list of all labels referred to other than by jumps. */ | |
451 | if (code == INSN || code == CALL_INSN) | |
452 | { | |
453 | rtx note = find_reg_note (insn, REG_LABEL, 0); | |
454 | if (note != 0) | |
455 | label_value_list = gen_rtx (EXPR_LIST, VOIDmode, XEXP (note, 0), | |
456 | label_value_list); | |
457 | } | |
458 | ||
459 | BLOCK_NUM (insn) = i; | |
460 | if (code != NOTE) | |
461 | prev_code = code; | |
462 | } | |
463 | if (i + 1 != n_basic_blocks) | |
464 | abort (); | |
465 | } | |
466 | ||
467 | /* Record which basic blocks control can drop in to. */ | |
468 | ||
469 | { | |
470 | register int i; | |
471 | for (i = 0; i < n_basic_blocks; i++) | |
472 | { | |
473 | register rtx insn = PREV_INSN (basic_block_head[i]); | |
474 | /* TEMP1 is used to avoid a bug in Sequent's compiler. */ | |
475 | register int temp1; | |
476 | while (insn && GET_CODE (insn) == NOTE) | |
477 | insn = PREV_INSN (insn); | |
478 | temp1 = insn && GET_CODE (insn) != BARRIER; | |
479 | basic_block_drops_in[i] = temp1; | |
480 | } | |
481 | } | |
482 | ||
483 | /* Now find which basic blocks can actually be reached | |
484 | and put all jump insns' LABEL_REFS onto the ref-chains | |
485 | of their target labels. */ | |
486 | ||
487 | if (n_basic_blocks > 0) | |
488 | { | |
489 | int something_marked = 1; | |
490 | ||
491 | /* Find all indirect jump insns and mark them as possibly jumping | |
492 | to all the labels whose addresses are explicitly used. | |
493 | This is because, when there are computed gotos, | |
494 | we can't tell which labels they jump to, of all the possibilities. */ | |
495 | ||
496 | for (insn = f; insn; insn = NEXT_INSN (insn)) | |
497 | if (GET_CODE (insn) == JUMP_INSN | |
498 | && GET_CODE (PATTERN (insn)) == SET | |
499 | && SET_DEST (PATTERN (insn)) == pc_rtx | |
500 | && GET_CODE (SET_SRC (PATTERN (insn))) == REG) | |
501 | { | |
502 | rtx x; | |
503 | for (x = label_value_list; x; x = XEXP (x, 1)) | |
504 | mark_label_ref (gen_rtx (LABEL_REF, VOIDmode, XEXP (x, 0)), | |
505 | insn, 0); | |
506 | for (x = forced_labels; x; x = XEXP (x, 1)) | |
507 | mark_label_ref (gen_rtx (LABEL_REF, VOIDmode, XEXP (x, 0)), | |
508 | insn, 0); | |
509 | } | |
510 | ||
511 | /* Pass over all blocks, marking each block that is reachable | |
512 | and has not yet been marked. | |
513 | Keep doing this until, in one pass, no blocks have been marked. | |
514 | Then blocks_live and blocks_marked are identical and correct. | |
515 | In addition, all jumps actually reachable have been marked. */ | |
516 | ||
517 | while (something_marked) | |
518 | { | |
519 | something_marked = 0; | |
520 | for (i = 0; i < n_basic_blocks; i++) | |
521 | if (block_live[i] && !block_marked[i]) | |
522 | { | |
523 | block_marked[i] = 1; | |
524 | something_marked = 1; | |
525 | if (i + 1 < n_basic_blocks && basic_block_drops_in[i + 1]) | |
526 | block_live[i + 1] = 1; | |
527 | insn = basic_block_end[i]; | |
528 | if (GET_CODE (insn) == JUMP_INSN) | |
529 | mark_label_ref (PATTERN (insn), insn, 0); | |
530 | } | |
531 | } | |
532 | ||
533 | /* Now delete the code for any basic blocks that can't be reached. | |
534 | They can occur because jump_optimize does not recognize | |
535 | unreachable loops as unreachable. */ | |
536 | ||
537 | for (i = 0; i < n_basic_blocks; i++) | |
538 | if (!block_live[i]) | |
539 | { | |
540 | insn = basic_block_head[i]; | |
541 | while (1) | |
542 | { | |
543 | if (GET_CODE (insn) == BARRIER) | |
544 | abort (); | |
545 | if (GET_CODE (insn) != NOTE) | |
546 | { | |
547 | PUT_CODE (insn, NOTE); | |
548 | NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED; | |
549 | NOTE_SOURCE_FILE (insn) = 0; | |
550 | } | |
551 | if (insn == basic_block_end[i]) | |
552 | { | |
553 | /* BARRIERs are between basic blocks, not part of one. | |
554 | Delete a BARRIER if the preceding jump is deleted. | |
555 | We cannot alter a BARRIER into a NOTE | |
556 | because it is too short; but we can really delete | |
557 | it because it is not part of a basic block. */ | |
558 | if (NEXT_INSN (insn) != 0 | |
559 | && GET_CODE (NEXT_INSN (insn)) == BARRIER) | |
560 | delete_insn (NEXT_INSN (insn)); | |
561 | break; | |
562 | } | |
563 | insn = NEXT_INSN (insn); | |
564 | } | |
565 | /* Each time we delete some basic blocks, | |
566 | see if there is a jump around them that is | |
567 | being turned into a no-op. If so, delete it. */ | |
568 | ||
569 | if (block_live[i - 1]) | |
570 | { | |
571 | register int j; | |
572 | for (j = i; j < n_basic_blocks; j++) | |
573 | if (block_live[j]) | |
574 | { | |
575 | rtx label; | |
576 | insn = basic_block_end[i - 1]; | |
577 | if (GET_CODE (insn) == JUMP_INSN | |
578 | /* An unconditional jump is the only possibility | |
579 | we must check for, since a conditional one | |
580 | would make these blocks live. */ | |
581 | && simplejump_p (insn) | |
582 | && (label = XEXP (SET_SRC (PATTERN (insn)), 0), 1) | |
583 | && INSN_UID (label) != 0 | |
584 | && BLOCK_NUM (label) == j) | |
585 | { | |
586 | PUT_CODE (insn, NOTE); | |
587 | NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED; | |
588 | NOTE_SOURCE_FILE (insn) = 0; | |
589 | if (GET_CODE (NEXT_INSN (insn)) != BARRIER) | |
590 | abort (); | |
591 | delete_insn (NEXT_INSN (insn)); | |
592 | } | |
593 | break; | |
594 | } | |
595 | } | |
596 | } | |
597 | } | |
598 | } | |
599 | \f | |
600 | /* Check expression X for label references; | |
601 | if one is found, add INSN to the label's chain of references. | |
602 | ||
603 | CHECKDUP means check for and avoid creating duplicate references | |
604 | from the same insn. Such duplicates do no serious harm but | |
605 | can slow life analysis. CHECKDUP is set only when duplicates | |
606 | are likely. */ | |
607 | ||
608 | static void | |
609 | mark_label_ref (x, insn, checkdup) | |
610 | rtx x, insn; | |
611 | int checkdup; | |
612 | { | |
613 | register RTX_CODE code; | |
614 | register int i; | |
615 | register char *fmt; | |
616 | ||
617 | /* We can be called with NULL when scanning label_value_list. */ | |
618 | if (x == 0) | |
619 | return; | |
620 | ||
621 | code = GET_CODE (x); | |
622 | if (code == LABEL_REF) | |
623 | { | |
624 | register rtx label = XEXP (x, 0); | |
625 | register rtx y; | |
626 | if (GET_CODE (label) != CODE_LABEL) | |
627 | abort (); | |
628 | /* If the label was never emitted, this insn is junk, | |
629 | but avoid a crash trying to refer to BLOCK_NUM (label). | |
630 | This can happen as a result of a syntax error | |
631 | and a diagnostic has already been printed. */ | |
632 | if (INSN_UID (label) == 0) | |
633 | return; | |
634 | CONTAINING_INSN (x) = insn; | |
635 | /* if CHECKDUP is set, check for duplicate ref from same insn | |
636 | and don't insert. */ | |
637 | if (checkdup) | |
638 | for (y = LABEL_REFS (label); y != label; y = LABEL_NEXTREF (y)) | |
639 | if (CONTAINING_INSN (y) == insn) | |
640 | return; | |
641 | LABEL_NEXTREF (x) = LABEL_REFS (label); | |
642 | LABEL_REFS (label) = x; | |
643 | block_live_static[BLOCK_NUM (label)] = 1; | |
644 | return; | |
645 | } | |
646 | ||
647 | fmt = GET_RTX_FORMAT (code); | |
648 | for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--) | |
649 | { | |
650 | if (fmt[i] == 'e') | |
651 | mark_label_ref (XEXP (x, i), insn, 0); | |
652 | if (fmt[i] == 'E') | |
653 | { | |
654 | register int j; | |
655 | for (j = 0; j < XVECLEN (x, i); j++) | |
656 | mark_label_ref (XVECEXP (x, i, j), insn, 1); | |
657 | } | |
658 | } | |
659 | } | |
660 | \f | |
661 | /* Determine which registers are live at the start of each | |
662 | basic block of the function whose first insn is F. | |
663 | NREGS is the number of registers used in F. | |
664 | We allocate the vector basic_block_live_at_start | |
665 | and the regsets that it points to, and fill them with the data. | |
666 | regset_size and regset_bytes are also set here. */ | |
667 | ||
668 | static void | |
669 | life_analysis (f, nregs) | |
670 | rtx f; | |
671 | int nregs; | |
672 | { | |
673 | register regset tem; | |
674 | int first_pass; | |
675 | int changed; | |
676 | /* For each basic block, a bitmask of regs | |
677 | live on exit from the block. */ | |
678 | regset *basic_block_live_at_end; | |
679 | /* For each basic block, a bitmask of regs | |
680 | live on entry to a successor-block of this block. | |
681 | If this does not match basic_block_live_at_end, | |
682 | that must be updated, and the block must be rescanned. */ | |
683 | regset *basic_block_new_live_at_end; | |
684 | /* For each basic block, a bitmask of regs | |
685 | whose liveness at the end of the basic block | |
686 | can make a difference in which regs are live on entry to the block. | |
687 | These are the regs that are set within the basic block, | |
688 | possibly excluding those that are used after they are set. */ | |
689 | regset *basic_block_significant; | |
690 | register int i; | |
691 | rtx insn; | |
692 | ||
693 | struct obstack flow_obstack; | |
694 | ||
695 | gcc_obstack_init (&flow_obstack); | |
696 | ||
697 | max_regno = nregs; | |
698 | ||
699 | bzero (regs_ever_live, sizeof regs_ever_live); | |
700 | ||
701 | /* Allocate and zero out many data structures | |
702 | that will record the data from lifetime analysis. */ | |
703 | ||
704 | allocate_for_life_analysis (); | |
705 | ||
706 | reg_next_use = (rtx *) alloca (nregs * sizeof (rtx)); | |
707 | bzero (reg_next_use, nregs * sizeof (rtx)); | |
708 | ||
709 | /* Set up several regset-vectors used internally within this function. | |
710 | Their meanings are documented above, with their declarations. */ | |
711 | ||
712 | basic_block_live_at_end = (regset *) alloca (n_basic_blocks * sizeof (regset)); | |
713 | /* Don't use alloca since that leads to a crash rather than an error message | |
714 | if there isn't enough space. | |
715 | Don't use oballoc since we may need to allocate other things during | |
716 | this function on the temporary obstack. */ | |
717 | tem = (regset) obstack_alloc (&flow_obstack, n_basic_blocks * regset_bytes); | |
718 | bzero (tem, n_basic_blocks * regset_bytes); | |
719 | init_regset_vector (basic_block_live_at_end, tem, n_basic_blocks, regset_bytes); | |
720 | ||
721 | basic_block_new_live_at_end = (regset *) alloca (n_basic_blocks * sizeof (regset)); | |
722 | tem = (regset) obstack_alloc (&flow_obstack, n_basic_blocks * regset_bytes); | |
723 | bzero (tem, n_basic_blocks * regset_bytes); | |
724 | init_regset_vector (basic_block_new_live_at_end, tem, n_basic_blocks, regset_bytes); | |
725 | ||
726 | basic_block_significant = (regset *) alloca (n_basic_blocks * sizeof (regset)); | |
727 | tem = (regset) obstack_alloc (&flow_obstack, n_basic_blocks * regset_bytes); | |
728 | bzero (tem, n_basic_blocks * regset_bytes); | |
729 | init_regset_vector (basic_block_significant, tem, n_basic_blocks, regset_bytes); | |
730 | ||
731 | /* Record which insns refer to any volatile memory | |
732 | or for any reason can't be deleted just because they are dead stores. | |
733 | Also, delete any insns that copy a register to itself. */ | |
734 | ||
735 | for (insn = f; insn; insn = NEXT_INSN (insn)) | |
736 | { | |
737 | enum rtx_code code1 = GET_CODE (insn); | |
738 | if (code1 == CALL_INSN) | |
739 | INSN_VOLATILE (insn) = 1; | |
740 | else if (code1 == INSN || code1 == JUMP_INSN) | |
741 | { | |
742 | /* Delete (in effect) any obvious no-op moves. */ | |
743 | if (GET_CODE (PATTERN (insn)) == SET | |
744 | && GET_CODE (SET_DEST (PATTERN (insn))) == REG | |
745 | && GET_CODE (SET_SRC (PATTERN (insn))) == REG | |
746 | && REGNO (SET_DEST (PATTERN (insn))) == | |
747 | REGNO (SET_SRC (PATTERN (insn))) | |
748 | /* Insns carrying these notes are useful later on. */ | |
749 | && ! find_reg_note (insn, REG_EQUAL, 0)) | |
750 | { | |
751 | PUT_CODE (insn, NOTE); | |
752 | NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED; | |
753 | NOTE_SOURCE_FILE (insn) = 0; | |
754 | } | |
755 | else if (GET_CODE (PATTERN (insn)) == PARALLEL) | |
756 | { | |
757 | /* If nothing but SETs of registers to themselves, | |
758 | this insn can also be deleted. */ | |
759 | for (i = 0; i < XVECLEN (PATTERN (insn), 0); i++) | |
760 | { | |
761 | rtx tem = XVECEXP (PATTERN (insn), 0, i); | |
762 | ||
763 | if (GET_CODE (tem) == USE | |
764 | || GET_CODE (tem) == CLOBBER) | |
765 | continue; | |
766 | ||
767 | if (GET_CODE (tem) != SET | |
768 | || GET_CODE (SET_DEST (tem)) != REG | |
769 | || GET_CODE (SET_SRC (tem)) != REG | |
770 | || REGNO (SET_DEST (tem)) != REGNO (SET_SRC (tem))) | |
771 | break; | |
772 | } | |
773 | ||
774 | if (i == XVECLEN (PATTERN (insn), 0) | |
775 | /* Insns carrying these notes are useful later on. */ | |
776 | && ! find_reg_note (insn, REG_EQUAL, 0)) | |
777 | { | |
778 | PUT_CODE (insn, NOTE); | |
779 | NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED; | |
780 | NOTE_SOURCE_FILE (insn) = 0; | |
781 | } | |
782 | else | |
783 | INSN_VOLATILE (insn) = volatile_refs_p (PATTERN (insn)); | |
784 | } | |
785 | else if (GET_CODE (PATTERN (insn)) != USE) | |
786 | INSN_VOLATILE (insn) = volatile_refs_p (PATTERN (insn)); | |
787 | /* A SET that makes space on the stack cannot be dead. | |
788 | (Such SETs occur only for allocating variable-size data, | |
789 | so they will always have a PLUS or MINUS according to the | |
790 | direction of stack growth.) | |
791 | Even if this function never uses this stack pointer value, | |
792 | signal handlers do! */ | |
793 | else if (code1 == INSN && GET_CODE (PATTERN (insn)) == SET | |
794 | && SET_DEST (PATTERN (insn)) == stack_pointer_rtx | |
795 | #ifdef STACK_GROWS_DOWNWARD | |
796 | && GET_CODE (SET_SRC (PATTERN (insn))) == MINUS | |
797 | #else | |
798 | && GET_CODE (SET_SRC (PATTERN (insn))) == PLUS | |
799 | #endif | |
800 | && XEXP (SET_SRC (PATTERN (insn)), 0) == stack_pointer_rtx) | |
801 | INSN_VOLATILE (insn) = 1; | |
802 | } | |
803 | } | |
804 | ||
805 | if (n_basic_blocks > 0) | |
806 | #ifdef EXIT_IGNORE_STACK | |
807 | if (! EXIT_IGNORE_STACK | |
808 | || (! FRAME_POINTER_REQUIRED && flag_omit_frame_pointer)) | |
809 | #endif | |
810 | { | |
811 | /* If exiting needs the right stack value, | |
812 | consider the stack pointer live at the end of the function. */ | |
813 | basic_block_live_at_end[n_basic_blocks - 1] | |
814 | [STACK_POINTER_REGNUM / REGSET_ELT_BITS] | |
815 | |= 1 << (STACK_POINTER_REGNUM % REGSET_ELT_BITS); | |
816 | basic_block_new_live_at_end[n_basic_blocks - 1] | |
817 | [STACK_POINTER_REGNUM / REGSET_ELT_BITS] | |
818 | |= 1 << (STACK_POINTER_REGNUM % REGSET_ELT_BITS); | |
819 | } | |
820 | ||
821 | /* Mark all global registers as being live at the end of the function | |
822 | since they may be referenced by our caller. */ | |
823 | ||
824 | if (n_basic_blocks > 0) | |
825 | for (i = 0; i < FIRST_PSEUDO_REGISTER; i++) | |
826 | if (global_regs[i]) | |
827 | { | |
828 | basic_block_live_at_end[n_basic_blocks - 1] | |
829 | [i / REGSET_ELT_BITS] |= 1 << (i % REGSET_ELT_BITS); | |
830 | basic_block_new_live_at_end[n_basic_blocks - 1] | |
831 | [i / REGSET_ELT_BITS] |= 1 << (i % REGSET_ELT_BITS); | |
832 | } | |
833 | ||
834 | /* Propagate life info through the basic blocks | |
835 | around the graph of basic blocks. | |
836 | ||
837 | This is a relaxation process: each time a new register | |
838 | is live at the end of the basic block, we must scan the block | |
839 | to determine which registers are, as a consequence, live at the beginning | |
840 | of that block. These registers must then be marked live at the ends | |
841 | of all the blocks that can transfer control to that block. | |
842 | The process continues until it reaches a fixed point. */ | |
843 | ||
844 | first_pass = 1; | |
845 | changed = 1; | |
846 | while (changed) | |
847 | { | |
848 | changed = 0; | |
849 | for (i = n_basic_blocks - 1; i >= 0; i--) | |
850 | { | |
851 | int consider = first_pass; | |
852 | int must_rescan = first_pass; | |
853 | register int j; | |
854 | ||
855 | if (!first_pass) | |
856 | { | |
857 | /* Set CONSIDER if this block needs thinking about at all | |
858 | (that is, if the regs live now at the end of it | |
859 | are not the same as were live at the end of it when | |
860 | we last thought about it). | |
861 | Set must_rescan if it needs to be thought about | |
862 | instruction by instruction (that is, if any additional | |
863 | reg that is live at the end now but was not live there before | |
864 | is one of the significant regs of this basic block). */ | |
865 | ||
866 | for (j = 0; j < regset_size; j++) | |
867 | { | |
868 | register int x = (basic_block_new_live_at_end[i][j] | |
869 | & ~basic_block_live_at_end[i][j]); | |
870 | if (x) | |
871 | consider = 1; | |
872 | if (x & basic_block_significant[i][j]) | |
873 | { | |
874 | must_rescan = 1; | |
875 | consider = 1; | |
876 | break; | |
877 | } | |
878 | } | |
879 | ||
880 | if (! consider) | |
881 | continue; | |
882 | } | |
883 | ||
884 | /* The live_at_start of this block may be changing, | |
885 | so another pass will be required after this one. */ | |
886 | changed = 1; | |
887 | ||
888 | if (! must_rescan) | |
889 | { | |
890 | /* No complete rescan needed; | |
891 | just record those variables newly known live at end | |
892 | as live at start as well. */ | |
893 | for (j = 0; j < regset_size; j++) | |
894 | { | |
895 | register int x = basic_block_new_live_at_end[i][j] | |
896 | & ~basic_block_live_at_end[i][j]; | |
897 | basic_block_live_at_start[i][j] |= x; | |
898 | basic_block_live_at_end[i][j] |= x; | |
899 | } | |
900 | } | |
901 | else | |
902 | { | |
903 | /* Update the basic_block_live_at_start | |
904 | by propagation backwards through the block. */ | |
905 | bcopy (basic_block_new_live_at_end[i], | |
906 | basic_block_live_at_end[i], regset_bytes); | |
907 | bcopy (basic_block_live_at_end[i], | |
908 | basic_block_live_at_start[i], regset_bytes); | |
909 | propagate_block (basic_block_live_at_start[i], | |
910 | basic_block_head[i], basic_block_end[i], 0, | |
911 | first_pass ? basic_block_significant[i] : 0, | |
912 | i); | |
913 | } | |
914 | ||
915 | { | |
916 | register rtx jump, head; | |
917 | /* Update the basic_block_new_live_at_end's of the block | |
918 | that falls through into this one (if any). */ | |
919 | head = basic_block_head[i]; | |
920 | jump = PREV_INSN (head); | |
921 | if (basic_block_drops_in[i]) | |
922 | { | |
923 | register int from_block = BLOCK_NUM (jump); | |
924 | register int j; | |
925 | for (j = 0; j < regset_size; j++) | |
926 | basic_block_new_live_at_end[from_block][j] | |
927 | |= basic_block_live_at_start[i][j]; | |
928 | } | |
929 | /* Update the basic_block_new_live_at_end's of | |
930 | all the blocks that jump to this one. */ | |
931 | if (GET_CODE (head) == CODE_LABEL) | |
932 | for (jump = LABEL_REFS (head); | |
933 | jump != head; | |
934 | jump = LABEL_NEXTREF (jump)) | |
935 | { | |
936 | register int from_block = BLOCK_NUM (CONTAINING_INSN (jump)); | |
937 | register int j; | |
938 | for (j = 0; j < regset_size; j++) | |
939 | basic_block_new_live_at_end[from_block][j] | |
940 | |= basic_block_live_at_start[i][j]; | |
941 | } | |
942 | } | |
943 | #ifdef USE_C_ALLOCA | |
944 | alloca (0); | |
945 | #endif | |
946 | } | |
947 | first_pass = 0; | |
948 | } | |
949 | ||
950 | /* The only pseudos that are live at the beginning of the function are | |
951 | those that were not set anywhere in the function. local-alloc doesn't | |
952 | know how to handle these correctly, so mark them as not local to any | |
953 | one basic block. */ | |
954 | ||
955 | if (n_basic_blocks > 0) | |
956 | for (i = FIRST_PSEUDO_REGISTER; i < max_regno; i++) | |
957 | if (basic_block_live_at_start[0][i / REGSET_ELT_BITS] | |
958 | & (1 << (i % REGSET_ELT_BITS))) | |
959 | reg_basic_block[i] = REG_BLOCK_GLOBAL; | |
960 | ||
961 | /* Now the life information is accurate. | |
962 | Make one more pass over each basic block | |
963 | to delete dead stores, create autoincrement addressing | |
964 | and record how many times each register is used, is set, or dies. | |
965 | ||
966 | To save time, we operate directly in basic_block_live_at_end[i], | |
967 | thus destroying it (in fact, converting it into a copy of | |
968 | basic_block_live_at_start[i]). This is ok now because | |
969 | basic_block_live_at_end[i] is no longer used past this point. */ | |
970 | ||
971 | max_scratch = 0; | |
972 | ||
973 | for (i = 0; i < n_basic_blocks; i++) | |
974 | { | |
975 | propagate_block (basic_block_live_at_end[i], | |
976 | basic_block_head[i], basic_block_end[i], 1, 0, i); | |
977 | #ifdef USE_C_ALLOCA | |
978 | alloca (0); | |
979 | #endif | |
980 | } | |
981 | ||
982 | #if 0 | |
983 | /* Something live during a setjmp should not be put in a register | |
984 | on certain machines which restore regs from stack frames | |
985 | rather than from the jmpbuf. | |
986 | But we don't need to do this for the user's variables, since | |
987 | ANSI says only volatile variables need this. */ | |
988 | #ifdef LONGJMP_RESTORE_FROM_STACK | |
989 | for (i = FIRST_PSEUDO_REGISTER; i < nregs; i++) | |
990 | if (regs_live_at_setjmp[i / REGSET_ELT_BITS] & (1 << (i % REGSET_ELT_BITS)) | |
991 | && regno_reg_rtx[i] != 0 && ! REG_USERVAR_P (regno_reg_rtx[i])) | |
992 | { | |
993 | reg_live_length[i] = -1; | |
994 | reg_basic_block[i] = -1; | |
995 | } | |
996 | #endif | |
997 | #endif | |
998 | ||
999 | /* We have a problem with any pseudoreg that | |
1000 | lives across the setjmp. ANSI says that if a | |
1001 | user variable does not change in value | |
1002 | between the setjmp and the longjmp, then the longjmp preserves it. | |
1003 | This includes longjmp from a place where the pseudo appears dead. | |
1004 | (In principle, the value still exists if it is in scope.) | |
1005 | If the pseudo goes in a hard reg, some other value may occupy | |
1006 | that hard reg where this pseudo is dead, thus clobbering the pseudo. | |
1007 | Conclusion: such a pseudo must not go in a hard reg. */ | |
1008 | for (i = FIRST_PSEUDO_REGISTER; i < nregs; i++) | |
1009 | if (regs_live_at_setjmp[i / REGSET_ELT_BITS] & (1 << (i % REGSET_ELT_BITS)) | |
1010 | && regno_reg_rtx[i] != 0) | |
1011 | { | |
1012 | reg_live_length[i] = -1; | |
1013 | reg_basic_block[i] = -1; | |
1014 | } | |
1015 | ||
1016 | obstack_free (&flow_obstack, 0); | |
1017 | } | |
1018 | \f | |
1019 | /* Subroutines of life analysis. */ | |
1020 | ||
1021 | /* Allocate the permanent data structures that represent the results | |
1022 | of life analysis. Not static since used also for stupid life analysis. */ | |
1023 | ||
1024 | void | |
1025 | allocate_for_life_analysis () | |
1026 | { | |
1027 | register int i; | |
1028 | register regset tem; | |
1029 | ||
1030 | regset_size = ((max_regno + REGSET_ELT_BITS - 1) / REGSET_ELT_BITS); | |
1031 | regset_bytes = regset_size * sizeof (*(regset)0); | |
1032 | ||
1033 | reg_n_refs = (int *) oballoc (max_regno * sizeof (int)); | |
1034 | bzero (reg_n_refs, max_regno * sizeof (int)); | |
1035 | ||
1036 | reg_n_sets = (short *) oballoc (max_regno * sizeof (short)); | |
1037 | bzero (reg_n_sets, max_regno * sizeof (short)); | |
1038 | ||
1039 | reg_n_deaths = (short *) oballoc (max_regno * sizeof (short)); | |
1040 | bzero (reg_n_deaths, max_regno * sizeof (short)); | |
1041 | ||
1042 | reg_live_length = (int *) oballoc (max_regno * sizeof (int)); | |
1043 | bzero (reg_live_length, max_regno * sizeof (int)); | |
1044 | ||
1045 | reg_n_calls_crossed = (int *) oballoc (max_regno * sizeof (int)); | |
1046 | bzero (reg_n_calls_crossed, max_regno * sizeof (int)); | |
1047 | ||
1048 | reg_basic_block = (short *) oballoc (max_regno * sizeof (short)); | |
1049 | for (i = 0; i < max_regno; i++) | |
1050 | reg_basic_block[i] = REG_BLOCK_UNKNOWN; | |
1051 | ||
1052 | basic_block_live_at_start = (regset *) oballoc (n_basic_blocks * sizeof (regset)); | |
1053 | tem = (regset) oballoc (n_basic_blocks * regset_bytes); | |
1054 | bzero (tem, n_basic_blocks * regset_bytes); | |
1055 | init_regset_vector (basic_block_live_at_start, tem, n_basic_blocks, regset_bytes); | |
1056 | ||
1057 | regs_live_at_setjmp = (regset) oballoc (regset_bytes); | |
1058 | bzero (regs_live_at_setjmp, regset_bytes); | |
1059 | } | |
1060 | ||
1061 | /* Make each element of VECTOR point at a regset, | |
1062 | taking the space for all those regsets from SPACE. | |
1063 | SPACE is of type regset, but it is really as long as NELTS regsets. | |
1064 | BYTES_PER_ELT is the number of bytes in one regset. */ | |
1065 | ||
1066 | static void | |
1067 | init_regset_vector (vector, space, nelts, bytes_per_elt) | |
1068 | regset *vector; | |
1069 | regset space; | |
1070 | int nelts; | |
1071 | int bytes_per_elt; | |
1072 | { | |
1073 | register int i; | |
1074 | register regset p = space; | |
1075 | ||
1076 | for (i = 0; i < nelts; i++) | |
1077 | { | |
1078 | vector[i] = p; | |
1079 | p += bytes_per_elt / sizeof (*p); | |
1080 | } | |
1081 | } | |
1082 | \f | |
1083 | /* Compute the registers live at the beginning of a basic block | |
1084 | from those live at the end. | |
1085 | ||
1086 | When called, OLD contains those live at the end. | |
1087 | On return, it contains those live at the beginning. | |
1088 | FIRST and LAST are the first and last insns of the basic block. | |
1089 | ||
1090 | FINAL is nonzero if we are doing the final pass which is not | |
1091 | for computing the life info (since that has already been done) | |
1092 | but for acting on it. On this pass, we delete dead stores, | |
1093 | set up the logical links and dead-variables lists of instructions, | |
1094 | and merge instructions for autoincrement and autodecrement addresses. | |
1095 | ||
1096 | SIGNIFICANT is nonzero only the first time for each basic block. | |
1097 | If it is nonzero, it points to a regset in which we store | |
1098 | a 1 for each register that is set within the block. | |
1099 | ||
1100 | BNUM is the number of the basic block. */ | |
1101 | ||
1102 | static void | |
1103 | propagate_block (old, first, last, final, significant, bnum) | |
1104 | register regset old; | |
1105 | rtx first; | |
1106 | rtx last; | |
1107 | int final; | |
1108 | regset significant; | |
1109 | int bnum; | |
1110 | { | |
1111 | register rtx insn; | |
1112 | rtx prev; | |
1113 | regset live; | |
1114 | regset dead; | |
1115 | ||
1116 | /* The following variables are used only if FINAL is nonzero. */ | |
1117 | /* This vector gets one element for each reg that has been live | |
1118 | at any point in the basic block that has been scanned so far. | |
1119 | SOMETIMES_MAX says how many elements are in use so far. | |
1120 | In each element, OFFSET is the byte-number within a regset | |
1121 | for the register described by the element, and BIT is a mask | |
1122 | for that register's bit within the byte. */ | |
1123 | register struct foo { short offset; short bit; } *regs_sometimes_live; | |
1124 | int sometimes_max = 0; | |
1125 | /* This regset has 1 for each reg that we have seen live so far. | |
1126 | It and REGS_SOMETIMES_LIVE are updated together. */ | |
1127 | regset maxlive; | |
1128 | ||
1129 | /* The loop depth may change in the middle of a basic block. Since we | |
1130 | scan from end to beginning, we start with the depth at the end of the | |
1131 | current basic block, and adjust as we pass ends and starts of loops. */ | |
1132 | loop_depth = basic_block_loop_depth[bnum]; | |
1133 | ||
1134 | dead = (regset) alloca (regset_bytes); | |
1135 | live = (regset) alloca (regset_bytes); | |
1136 | ||
1137 | cc0_live = 0; | |
1138 | last_mem_set = 0; | |
1139 | ||
1140 | /* Include any notes at the end of the block in the scan. | |
1141 | This is in case the block ends with a call to setjmp. */ | |
1142 | ||
1143 | while (NEXT_INSN (last) != 0 && GET_CODE (NEXT_INSN (last)) == NOTE) | |
1144 | { | |
1145 | /* Look for loop boundaries, we are going forward here. */ | |
1146 | last = NEXT_INSN (last); | |
1147 | if (NOTE_LINE_NUMBER (last) == NOTE_INSN_LOOP_BEG) | |
1148 | loop_depth++; | |
1149 | else if (NOTE_LINE_NUMBER (last) == NOTE_INSN_LOOP_END) | |
1150 | loop_depth--; | |
1151 | } | |
1152 | ||
1153 | if (final) | |
1154 | { | |
1155 | register int i, offset, bit; | |
1156 | ||
1157 | num_scratch = 0; | |
1158 | maxlive = (regset) alloca (regset_bytes); | |
1159 | bcopy (old, maxlive, regset_bytes); | |
1160 | regs_sometimes_live | |
1161 | = (struct foo *) alloca (max_regno * sizeof (struct foo)); | |
1162 | ||
1163 | /* Process the regs live at the end of the block. | |
1164 | Enter them in MAXLIVE and REGS_SOMETIMES_LIVE. | |
1165 | Also mark them as not local to any one basic block. */ | |
1166 | ||
1167 | for (offset = 0, i = 0; offset < regset_size; offset++) | |
1168 | for (bit = 1; bit; bit <<= 1, i++) | |
1169 | { | |
1170 | if (i == max_regno) | |
1171 | break; | |
1172 | if (old[offset] & bit) | |
1173 | { | |
1174 | reg_basic_block[i] = REG_BLOCK_GLOBAL; | |
1175 | regs_sometimes_live[sometimes_max].offset = offset; | |
1176 | regs_sometimes_live[sometimes_max].bit = i % REGSET_ELT_BITS; | |
1177 | sometimes_max++; | |
1178 | } | |
1179 | } | |
1180 | } | |
1181 | ||
1182 | /* Scan the block an insn at a time from end to beginning. */ | |
1183 | ||
1184 | for (insn = last; ; insn = prev) | |
1185 | { | |
1186 | prev = PREV_INSN (insn); | |
1187 | ||
1188 | /* Look for loop boundaries, remembering that we are going backwards. */ | |
1189 | if (GET_CODE (insn) == NOTE | |
1190 | && NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_END) | |
1191 | loop_depth++; | |
1192 | else if (GET_CODE (insn) == NOTE | |
1193 | && NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG) | |
1194 | loop_depth--; | |
1195 | ||
1196 | /* If we have LOOP_DEPTH == 0, there has been a bookkeeping error. | |
1197 | Abort now rather than setting register status incorrectly. */ | |
1198 | if (loop_depth == 0) | |
1199 | abort (); | |
1200 | ||
1201 | /* If this is a call to `setjmp' et al, | |
1202 | warn if any non-volatile datum is live. */ | |
1203 | ||
1204 | if (final && GET_CODE (insn) == NOTE | |
1205 | && NOTE_LINE_NUMBER (insn) == NOTE_INSN_SETJMP) | |
1206 | { | |
1207 | int i; | |
1208 | for (i = 0; i < regset_size; i++) | |
1209 | regs_live_at_setjmp[i] |= old[i]; | |
1210 | } | |
1211 | ||
1212 | /* Update the life-status of regs for this insn. | |
1213 | First DEAD gets which regs are set in this insn | |
1214 | then LIVE gets which regs are used in this insn. | |
1215 | Then the regs live before the insn | |
1216 | are those live after, with DEAD regs turned off, | |
1217 | and then LIVE regs turned on. */ | |
1218 | ||
1219 | if (GET_RTX_CLASS (GET_CODE (insn)) == 'i') | |
1220 | { | |
1221 | register int i; | |
1222 | rtx note = find_reg_note (insn, REG_RETVAL, 0); | |
1223 | int insn_is_dead | |
1224 | = (insn_dead_p (PATTERN (insn), old, 0) | |
1225 | /* Don't delete something that refers to volatile storage! */ | |
1226 | && ! INSN_VOLATILE (insn)); | |
1227 | int libcall_is_dead | |
1228 | = (insn_is_dead && note != 0 | |
1229 | && libcall_dead_p (PATTERN (insn), old, note, insn)); | |
1230 | ||
1231 | /* If an instruction consists of just dead store(s) on final pass, | |
1232 | "delete" it by turning it into a NOTE of type NOTE_INSN_DELETED. | |
1233 | We could really delete it with delete_insn, but that | |
1234 | can cause trouble for first or last insn in a basic block. */ | |
1235 | if (final && insn_is_dead) | |
1236 | { | |
1237 | PUT_CODE (insn, NOTE); | |
1238 | NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED; | |
1239 | NOTE_SOURCE_FILE (insn) = 0; | |
1240 | ||
1241 | /* If this insn is copying the return value from a library call, | |
1242 | delete the entire library call. */ | |
1243 | if (libcall_is_dead) | |
1244 | { | |
1245 | rtx first = XEXP (note, 0); | |
1246 | rtx p = insn; | |
1247 | while (INSN_DELETED_P (first)) | |
1248 | first = NEXT_INSN (first); | |
1249 | while (p != first) | |
1250 | { | |
1251 | p = PREV_INSN (p); | |
1252 | PUT_CODE (p, NOTE); | |
1253 | NOTE_LINE_NUMBER (p) = NOTE_INSN_DELETED; | |
1254 | NOTE_SOURCE_FILE (p) = 0; | |
1255 | } | |
1256 | } | |
1257 | goto flushed; | |
1258 | } | |
1259 | ||
1260 | for (i = 0; i < regset_size; i++) | |
1261 | { | |
1262 | dead[i] = 0; /* Faster than bzero here */ | |
1263 | live[i] = 0; /* since regset_size is usually small */ | |
1264 | } | |
1265 | ||
1266 | /* See if this is an increment or decrement that can be | |
1267 | merged into a following memory address. */ | |
1268 | #ifdef AUTO_INC_DEC | |
1269 | { | |
1270 | register rtx x = PATTERN (insn); | |
1271 | /* Does this instruction increment or decrement a register? */ | |
1272 | if (final && GET_CODE (x) == SET | |
1273 | && GET_CODE (SET_DEST (x)) == REG | |
1274 | && (GET_CODE (SET_SRC (x)) == PLUS | |
1275 | || GET_CODE (SET_SRC (x)) == MINUS) | |
1276 | && XEXP (SET_SRC (x), 0) == SET_DEST (x) | |
1277 | && GET_CODE (XEXP (SET_SRC (x), 1)) == CONST_INT | |
1278 | /* Ok, look for a following memory ref we can combine with. | |
1279 | If one is found, change the memory ref to a PRE_INC | |
1280 | or PRE_DEC, cancel this insn, and return 1. | |
1281 | Return 0 if nothing has been done. */ | |
1282 | && try_pre_increment_1 (insn)) | |
1283 | goto flushed; | |
1284 | } | |
1285 | #endif /* AUTO_INC_DEC */ | |
1286 | ||
1287 | /* If this is not the final pass, and this insn is copying the | |
1288 | value of a library call and it's dead, don't scan the | |
1289 | insns that perform the library call, so that the call's | |
1290 | arguments are not marked live. */ | |
1291 | if (libcall_is_dead) | |
1292 | { | |
1293 | /* Mark the dest reg as `significant'. */ | |
1294 | mark_set_regs (old, dead, PATTERN (insn), 0, significant); | |
1295 | ||
1296 | insn = XEXP (note, 0); | |
1297 | prev = PREV_INSN (insn); | |
1298 | } | |
1299 | else if (GET_CODE (PATTERN (insn)) == SET | |
1300 | && SET_DEST (PATTERN (insn)) == stack_pointer_rtx | |
1301 | && GET_CODE (SET_SRC (PATTERN (insn))) == PLUS | |
1302 | && XEXP (SET_SRC (PATTERN (insn)), 0) == stack_pointer_rtx | |
1303 | && GET_CODE (XEXP (SET_SRC (PATTERN (insn)), 1)) == CONST_INT) | |
1304 | /* We have an insn to pop a constant amount off the stack. | |
1305 | (Such insns use PLUS regardless of the direction of the stack, | |
1306 | and any insn to adjust the stack by a constant is always a pop.) | |
1307 | These insns, if not dead stores, have no effect on life. */ | |
1308 | ; | |
1309 | else | |
1310 | { | |
1311 | /* LIVE gets the regs used in INSN; | |
1312 | DEAD gets those set by it. Dead insns don't make anything | |
1313 | live. */ | |
1314 | ||
1315 | mark_set_regs (old, dead, PATTERN (insn), final ? insn : 0, | |
1316 | significant); | |
1317 | ||
1318 | /* If an insn doesn't use CC0, it becomes dead since we | |
1319 | assume that every insn clobbers it. So show it dead here; | |
1320 | mark_used_regs will set it live if it is referenced. */ | |
1321 | cc0_live = 0; | |
1322 | ||
1323 | if (! insn_is_dead) | |
1324 | mark_used_regs (old, live, PATTERN (insn), final, insn); | |
1325 | ||
1326 | /* Sometimes we may have inserted something before INSN (such as | |
1327 | a move) when we make an auto-inc. So ensure we will scan | |
1328 | those insns. */ | |
1329 | #ifdef AUTO_INC_DEC | |
1330 | prev = PREV_INSN (insn); | |
1331 | #endif | |
1332 | ||
1333 | if (! insn_is_dead && GET_CODE (insn) == CALL_INSN) | |
1334 | { | |
1335 | register int i; | |
1336 | ||
1337 | /* Each call clobbers all call-clobbered regs that are not | |
1338 | global. Note that the function-value reg is a | |
1339 | call-clobbered reg, and mark_set_regs has already had | |
1340 | a chance to handle it. */ | |
1341 | ||
1342 | for (i = 0; i < FIRST_PSEUDO_REGISTER; i++) | |
1343 | if (call_used_regs[i] && ! global_regs[i]) | |
1344 | dead[i / REGSET_ELT_BITS] | |
1345 | |= (1 << (i % REGSET_ELT_BITS)); | |
1346 | ||
1347 | /* The stack ptr is used (honorarily) by a CALL insn. */ | |
1348 | live[STACK_POINTER_REGNUM / REGSET_ELT_BITS] | |
1349 | |= (1 << (STACK_POINTER_REGNUM % REGSET_ELT_BITS)); | |
1350 | ||
1351 | /* Calls may also reference any of the global registers, | |
1352 | so they are made live. */ | |
1353 | ||
1354 | for (i = 0; i < FIRST_PSEUDO_REGISTER; i++) | |
1355 | if (global_regs[i]) | |
1356 | live[i / REGSET_ELT_BITS] | |
1357 | |= (1 << (i % REGSET_ELT_BITS)); | |
1358 | ||
1359 | /* Calls also clobber memory. */ | |
1360 | last_mem_set = 0; | |
1361 | } | |
1362 | ||
1363 | /* Update OLD for the registers used or set. */ | |
1364 | for (i = 0; i < regset_size; i++) | |
1365 | { | |
1366 | old[i] &= ~dead[i]; | |
1367 | old[i] |= live[i]; | |
1368 | } | |
1369 | ||
1370 | if (GET_CODE (insn) == CALL_INSN && final) | |
1371 | { | |
1372 | /* Any regs live at the time of a call instruction | |
1373 | must not go in a register clobbered by calls. | |
1374 | Find all regs now live and record this for them. */ | |
1375 | ||
1376 | register struct foo *p = regs_sometimes_live; | |
1377 | ||
1378 | for (i = 0; i < sometimes_max; i++, p++) | |
1379 | if (old[p->offset] & (1 << p->bit)) | |
1380 | reg_n_calls_crossed[p->offset * REGSET_ELT_BITS + p->bit]+= 1; | |
1381 | } | |
1382 | } | |
1383 | ||
1384 | /* On final pass, add any additional sometimes-live regs | |
1385 | into MAXLIVE and REGS_SOMETIMES_LIVE. | |
1386 | Also update counts of how many insns each reg is live at. */ | |
1387 | ||
1388 | if (final) | |
1389 | { | |
1390 | for (i = 0; i < regset_size; i++) | |
1391 | { | |
1392 | register int diff = live[i] & ~maxlive[i]; | |
1393 | ||
1394 | if (diff) | |
1395 | { | |
1396 | register int regno; | |
1397 | maxlive[i] |= diff; | |
1398 | for (regno = 0; diff && regno < REGSET_ELT_BITS; regno++) | |
1399 | if (diff & (1 << regno)) | |
1400 | { | |
1401 | regs_sometimes_live[sometimes_max].offset = i; | |
1402 | regs_sometimes_live[sometimes_max].bit = regno; | |
1403 | diff &= ~ (1 << regno); | |
1404 | sometimes_max++; | |
1405 | } | |
1406 | } | |
1407 | } | |
1408 | ||
1409 | { | |
1410 | register struct foo *p = regs_sometimes_live; | |
1411 | for (i = 0; i < sometimes_max; i++, p++) | |
1412 | { | |
1413 | if (old[p->offset] & (1 << p->bit)) | |
1414 | reg_live_length[p->offset * REGSET_ELT_BITS + p->bit]++; | |
1415 | } | |
1416 | } | |
1417 | } | |
1418 | } | |
1419 | flushed: ; | |
1420 | if (insn == first) | |
1421 | break; | |
1422 | } | |
1423 | ||
1424 | if (num_scratch > max_scratch) | |
1425 | max_scratch = num_scratch; | |
1426 | } | |
1427 | \f | |
1428 | /* Return 1 if X (the body of an insn, or part of it) is just dead stores | |
1429 | (SET expressions whose destinations are registers dead after the insn). | |
1430 | NEEDED is the regset that says which regs are alive after the insn. | |
1431 | ||
1432 | Unless CALL_OK is non-zero, an insn is needed if it contains a CALL. */ | |
1433 | ||
1434 | static int | |
1435 | insn_dead_p (x, needed, call_ok) | |
1436 | rtx x; | |
1437 | regset needed; | |
1438 | int call_ok; | |
1439 | { | |
1440 | register RTX_CODE code = GET_CODE (x); | |
1441 | /* If setting something that's a reg or part of one, | |
1442 | see if that register's altered value will be live. */ | |
1443 | ||
1444 | if (code == SET) | |
1445 | { | |
1446 | register rtx r = SET_DEST (x); | |
1447 | /* A SET that is a subroutine call cannot be dead. */ | |
1448 | if (! call_ok && GET_CODE (SET_SRC (x)) == CALL) | |
1449 | return 0; | |
1450 | ||
1451 | #ifdef HAVE_cc0 | |
1452 | if (GET_CODE (r) == CC0) | |
1453 | return ! cc0_live; | |
1454 | #endif | |
1455 | ||
1456 | if (GET_CODE (r) == MEM && last_mem_set && ! MEM_VOLATILE_P (r) | |
1457 | && rtx_equal_p (r, last_mem_set)) | |
1458 | return 1; | |
1459 | ||
1460 | while (GET_CODE (r) == SUBREG | |
1461 | || GET_CODE (r) == STRICT_LOW_PART | |
1462 | || GET_CODE (r) == ZERO_EXTRACT | |
1463 | || GET_CODE (r) == SIGN_EXTRACT) | |
1464 | r = SUBREG_REG (r); | |
1465 | ||
1466 | if (GET_CODE (r) == REG) | |
1467 | { | |
1468 | register int regno = REGNO (r); | |
1469 | register int offset = regno / REGSET_ELT_BITS; | |
1470 | register int bit = 1 << (regno % REGSET_ELT_BITS); | |
1471 | ||
1472 | if ((regno < FIRST_PSEUDO_REGISTER && global_regs[regno]) | |
1473 | /* Make sure insns to set frame pointer aren't deleted. */ | |
1474 | || regno == FRAME_POINTER_REGNUM | |
1475 | /* Make sure insns to set arg pointer are never deleted. */ | |
1476 | || regno == ARG_POINTER_REGNUM | |
1477 | || (needed[offset] & bit) != 0) | |
1478 | return 0; | |
1479 | ||
1480 | /* If this is a hard register, verify that subsequent words are | |
1481 | not needed. */ | |
1482 | if (regno < FIRST_PSEUDO_REGISTER) | |
1483 | { | |
1484 | int n = HARD_REGNO_NREGS (regno, GET_MODE (r)); | |
1485 | ||
1486 | while (--n > 0) | |
1487 | if ((needed[(regno + n) / REGSET_ELT_BITS] | |
1488 | & 1 << ((regno + n) % REGSET_ELT_BITS)) != 0) | |
1489 | return 0; | |
1490 | } | |
1491 | ||
1492 | return 1; | |
1493 | } | |
1494 | } | |
1495 | /* If performing several activities, | |
1496 | insn is dead if each activity is individually dead. | |
1497 | Also, CLOBBERs and USEs can be ignored; a CLOBBER or USE | |
1498 | that's inside a PARALLEL doesn't make the insn worth keeping. */ | |
1499 | else if (code == PARALLEL) | |
1500 | { | |
1501 | register int i = XVECLEN (x, 0); | |
1502 | for (i--; i >= 0; i--) | |
1503 | { | |
1504 | rtx elt = XVECEXP (x, 0, i); | |
1505 | if (!insn_dead_p (elt, needed, call_ok) | |
1506 | && GET_CODE (elt) != CLOBBER | |
1507 | && GET_CODE (elt) != USE) | |
1508 | return 0; | |
1509 | } | |
1510 | return 1; | |
1511 | } | |
1512 | /* We do not check CLOBBER or USE here. | |
1513 | An insn consisting of just a CLOBBER or just a USE | |
1514 | should not be deleted. */ | |
1515 | return 0; | |
1516 | } | |
1517 | ||
1518 | /* If X is the pattern of the last insn in a libcall, and assuming X is dead, | |
1519 | return 1 if the entire library call is dead. | |
1520 | This is true if X copies a register (hard or pseudo) | |
1521 | and if the hard return reg of the call insn is dead. | |
1522 | (The caller should have tested the destination of X already for death.) | |
1523 | ||
1524 | If this insn doesn't just copy a register, then we don't | |
1525 | have an ordinary libcall. In that case, cse could not have | |
1526 | managed to substitute the source for the dest later on, | |
1527 | so we can assume the libcall is dead. | |
1528 | ||
1529 | NEEDED is the bit vector of pseudoregs live before this insn. | |
1530 | NOTE is the REG_RETVAL note of the insn. INSN is the insn itself. */ | |
1531 | ||
1532 | static int | |
1533 | libcall_dead_p (x, needed, note, insn) | |
1534 | rtx x; | |
1535 | regset needed; | |
1536 | rtx note; | |
1537 | rtx insn; | |
1538 | { | |
1539 | register RTX_CODE code = GET_CODE (x); | |
1540 | ||
1541 | if (code == SET) | |
1542 | { | |
1543 | register rtx r = SET_SRC (x); | |
1544 | if (GET_CODE (r) == REG) | |
1545 | { | |
1546 | rtx call = XEXP (note, 0); | |
1547 | register int i; | |
1548 | ||
1549 | /* Find the call insn. */ | |
1550 | while (call != insn && GET_CODE (call) != CALL_INSN) | |
1551 | call = NEXT_INSN (call); | |
1552 | ||
1553 | /* If there is none, do nothing special, | |
1554 | since ordinary death handling can understand these insns. */ | |
1555 | if (call == insn) | |
1556 | return 0; | |
1557 | ||
1558 | /* See if the hard reg holding the value is dead. | |
1559 | If this is a PARALLEL, find the call within it. */ | |
1560 | call = PATTERN (call); | |
1561 | if (GET_CODE (call) == PARALLEL) | |
1562 | { | |
1563 | for (i = XVECLEN (call, 0) - 1; i >= 0; i--) | |
1564 | if (GET_CODE (XVECEXP (call, 0, i)) == SET | |
1565 | && GET_CODE (SET_SRC (XVECEXP (call, 0, i))) == CALL) | |
1566 | break; | |
1567 | ||
1568 | if (i < 0) | |
1569 | abort (); | |
1570 | ||
1571 | call = XVECEXP (call, 0, i); | |
1572 | } | |
1573 | ||
1574 | return insn_dead_p (call, needed, 1); | |
1575 | } | |
1576 | } | |
1577 | return 1; | |
1578 | } | |
1579 | ||
1580 | /* Return 1 if register REGNO was used before it was set. | |
1581 | In other words, if it is live at function entry. */ | |
1582 | ||
1583 | int | |
1584 | regno_uninitialized (regno) | |
1585 | int regno; | |
1586 | { | |
1587 | if (n_basic_blocks == 0) | |
1588 | return 0; | |
1589 | ||
1590 | return (basic_block_live_at_start[0][regno / REGSET_ELT_BITS] | |
1591 | & (1 << (regno % REGSET_ELT_BITS))); | |
1592 | } | |
1593 | ||
1594 | /* 1 if register REGNO was alive at a place where `setjmp' was called | |
1595 | and was set more than once or is an argument. | |
1596 | Such regs may be clobbered by `longjmp'. */ | |
1597 | ||
1598 | int | |
1599 | regno_clobbered_at_setjmp (regno) | |
1600 | int regno; | |
1601 | { | |
1602 | if (n_basic_blocks == 0) | |
1603 | return 0; | |
1604 | ||
1605 | return ((reg_n_sets[regno] > 1 | |
1606 | || (basic_block_live_at_start[0][regno / REGSET_ELT_BITS] | |
1607 | & (1 << (regno % REGSET_ELT_BITS)))) | |
1608 | && (regs_live_at_setjmp[regno / REGSET_ELT_BITS] | |
1609 | & (1 << (regno % REGSET_ELT_BITS)))); | |
1610 | } | |
1611 | \f | |
1612 | /* Process the registers that are set within X. | |
1613 | Their bits are set to 1 in the regset DEAD, | |
1614 | because they are dead prior to this insn. | |
1615 | ||
1616 | If INSN is nonzero, it is the insn being processed | |
1617 | and the fact that it is nonzero implies this is the FINAL pass | |
1618 | in propagate_block. In this case, various info about register | |
1619 | usage is stored, LOG_LINKS fields of insns are set up. */ | |
1620 | ||
1621 | static void mark_set_1 (); | |
1622 | ||
1623 | static void | |
1624 | mark_set_regs (needed, dead, x, insn, significant) | |
1625 | regset needed; | |
1626 | regset dead; | |
1627 | rtx x; | |
1628 | rtx insn; | |
1629 | regset significant; | |
1630 | { | |
1631 | register RTX_CODE code = GET_CODE (x); | |
1632 | ||
1633 | if (code == SET || code == CLOBBER) | |
1634 | mark_set_1 (needed, dead, x, insn, significant); | |
1635 | else if (code == PARALLEL) | |
1636 | { | |
1637 | register int i; | |
1638 | for (i = XVECLEN (x, 0) - 1; i >= 0; i--) | |
1639 | { | |
1640 | code = GET_CODE (XVECEXP (x, 0, i)); | |
1641 | if (code == SET || code == CLOBBER) | |
1642 | mark_set_1 (needed, dead, XVECEXP (x, 0, i), insn, significant); | |
1643 | } | |
1644 | } | |
1645 | } | |
1646 | ||
1647 | /* Process a single SET rtx, X. */ | |
1648 | ||
1649 | static void | |
1650 | mark_set_1 (needed, dead, x, insn, significant) | |
1651 | regset needed; | |
1652 | regset dead; | |
1653 | rtx x; | |
1654 | rtx insn; | |
1655 | regset significant; | |
1656 | { | |
1657 | register int regno; | |
1658 | register rtx reg = SET_DEST (x); | |
1659 | ||
1660 | /* Modifying just one hardware register of a multi-reg value | |
1661 | or just a byte field of a register | |
1662 | does not mean the value from before this insn is now dead. | |
1663 | But it does mean liveness of that register at the end of the block | |
1664 | is significant. | |
1665 | ||
1666 | Within mark_set_1, however, we treat it as if the register is | |
1667 | indeed modified. mark_used_regs will, however, also treat this | |
1668 | register as being used. Thus, we treat these insns as setting a | |
1669 | new value for the register as a function of its old value. This | |
1670 | cases LOG_LINKS to be made appropriately and this will help combine. */ | |
1671 | ||
1672 | while (GET_CODE (reg) == SUBREG || GET_CODE (reg) == ZERO_EXTRACT | |
1673 | || GET_CODE (reg) == SIGN_EXTRACT | |
1674 | || GET_CODE (reg) == STRICT_LOW_PART) | |
1675 | reg = XEXP (reg, 0); | |
1676 | ||
1677 | /* If we are writing into memory or into a register mentioned in the | |
1678 | address of the last thing stored into memory, show we don't know | |
1679 | what the last store was. If we are writing memory, save the address | |
1680 | unless it is volatile. */ | |
1681 | if (GET_CODE (reg) == MEM | |
1682 | || (GET_CODE (reg) == REG | |
1683 | && last_mem_set != 0 && reg_overlap_mentioned_p (reg, last_mem_set))) | |
1684 | last_mem_set = 0; | |
1685 | ||
1686 | if (GET_CODE (reg) == MEM && ! side_effects_p (reg) | |
1687 | /* There are no REG_INC notes for SP, so we can't assume we'll see | |
1688 | everything that invalidates it. To be safe, don't eliminate any | |
1689 | stores though SP; none of them should be redundant anyway. */ | |
1690 | && ! reg_mentioned_p (stack_pointer_rtx, reg)) | |
1691 | last_mem_set = reg; | |
1692 | ||
1693 | if (GET_CODE (reg) == REG | |
1694 | && (regno = REGNO (reg), regno != FRAME_POINTER_REGNUM) | |
1695 | && regno != ARG_POINTER_REGNUM | |
1696 | && ! (regno < FIRST_PSEUDO_REGISTER && global_regs[regno])) | |
1697 | /* && regno != STACK_POINTER_REGNUM) -- let's try without this. */ | |
1698 | { | |
1699 | register int offset = regno / REGSET_ELT_BITS; | |
1700 | register int bit = 1 << (regno % REGSET_ELT_BITS); | |
1701 | int all_needed = (needed[offset] & bit) != 0; | |
1702 | int some_needed = (needed[offset] & bit) != 0; | |
1703 | ||
1704 | /* Mark it as a significant register for this basic block. */ | |
1705 | if (significant) | |
1706 | significant[offset] |= bit; | |
1707 | ||
1708 | /* Mark it as as dead before this insn. */ | |
1709 | dead[offset] |= bit; | |
1710 | ||
1711 | /* A hard reg in a wide mode may really be multiple registers. | |
1712 | If so, mark all of them just like the first. */ | |
1713 | if (regno < FIRST_PSEUDO_REGISTER) | |
1714 | { | |
1715 | int n; | |
1716 | ||
1717 | /* Nothing below is needed for the stack pointer; get out asap. | |
1718 | Eg, log links aren't needed, since combine won't use them. */ | |
1719 | if (regno == STACK_POINTER_REGNUM) | |
1720 | return; | |
1721 | ||
1722 | n = HARD_REGNO_NREGS (regno, GET_MODE (reg)); | |
1723 | while (--n > 0) | |
1724 | { | |
1725 | if (significant) | |
1726 | significant[(regno + n) / REGSET_ELT_BITS] | |
1727 | |= 1 << ((regno + n) % REGSET_ELT_BITS); | |
1728 | dead[(regno + n) / REGSET_ELT_BITS] | |
1729 | |= 1 << ((regno + n) % REGSET_ELT_BITS); | |
1730 | some_needed |= (needed[(regno + n) / REGSET_ELT_BITS] | |
1731 | & 1 << ((regno + n) % REGSET_ELT_BITS)); | |
1732 | all_needed &= (needed[(regno + n) / REGSET_ELT_BITS] | |
1733 | & 1 << ((regno + n) % REGSET_ELT_BITS)); | |
1734 | } | |
1735 | } | |
1736 | /* Additional data to record if this is the final pass. */ | |
1737 | if (insn) | |
1738 | { | |
1739 | register rtx y = reg_next_use[regno]; | |
1740 | register int blocknum = BLOCK_NUM (insn); | |
1741 | ||
1742 | /* If this is a hard reg, record this function uses the reg. */ | |
1743 | ||
1744 | if (regno < FIRST_PSEUDO_REGISTER) | |
1745 | { | |
1746 | register int i; | |
1747 | int endregno = regno + HARD_REGNO_NREGS (regno, GET_MODE (reg)); | |
1748 | ||
1749 | for (i = regno; i < endregno; i++) | |
1750 | { | |
1751 | regs_ever_live[i] = 1; | |
1752 | reg_n_sets[i]++; | |
1753 | } | |
1754 | } | |
1755 | else | |
1756 | { | |
1757 | /* Keep track of which basic blocks each reg appears in. */ | |
1758 | ||
1759 | if (reg_basic_block[regno] == REG_BLOCK_UNKNOWN) | |
1760 | reg_basic_block[regno] = blocknum; | |
1761 | else if (reg_basic_block[regno] != blocknum) | |
1762 | reg_basic_block[regno] = REG_BLOCK_GLOBAL; | |
1763 | ||
1764 | /* Count (weighted) references, stores, etc. This counts a | |
1765 | register twice if it is modified, but that is correct. */ | |
1766 | reg_n_sets[regno]++; | |
1767 | ||
1768 | reg_n_refs[regno] += loop_depth; | |
1769 | ||
1770 | /* The insns where a reg is live are normally counted | |
1771 | elsewhere, but we want the count to include the insn | |
1772 | where the reg is set, and the normal counting mechanism | |
1773 | would not count it. */ | |
1774 | reg_live_length[regno]++; | |
1775 | } | |
1776 | ||
1777 | /* The next use is no longer "next", since a store intervenes. */ | |
1778 | reg_next_use[regno] = 0; | |
1779 | ||
1780 | if (all_needed) | |
1781 | { | |
1782 | /* Make a logical link from the next following insn | |
1783 | that uses this register, back to this insn. | |
1784 | The following insns have already been processed. | |
1785 | ||
1786 | We don't build a LOG_LINK for hard registers containing | |
1787 | in ASM_OPERANDs. If these registers get replaced, | |
1788 | we might wind up changing the semantics of the insn, | |
1789 | even if reload can make what appear to be valid assignments | |
1790 | later. */ | |
1791 | if (y && (BLOCK_NUM (y) == blocknum) | |
1792 | && (regno >= FIRST_PSEUDO_REGISTER | |
1793 | || asm_noperands (PATTERN (y)) < 0)) | |
1794 | LOG_LINKS (y) | |
1795 | = gen_rtx (INSN_LIST, VOIDmode, insn, LOG_LINKS (y)); | |
1796 | } | |
1797 | else if (! some_needed) | |
1798 | { | |
1799 | /* Note that dead stores have already been deleted when possible | |
1800 | If we get here, we have found a dead store that cannot | |
1801 | be eliminated (because the same insn does something useful). | |
1802 | Indicate this by marking the reg being set as dying here. */ | |
1803 | REG_NOTES (insn) | |
1804 | = gen_rtx (EXPR_LIST, REG_UNUSED, reg, REG_NOTES (insn)); | |
1805 | reg_n_deaths[REGNO (reg)]++; | |
1806 | } | |
1807 | else | |
1808 | { | |
1809 | /* This is a case where we have a multi-word hard register | |
1810 | and some, but not all, of the words of the register are | |
1811 | needed in subsequent insns. Write REG_UNUSED notes | |
1812 | for those parts that were not needed. This case should | |
1813 | be rare. */ | |
1814 | ||
1815 | int i; | |
1816 | ||
1817 | for (i = HARD_REGNO_NREGS (regno, GET_MODE (reg)) - 1; | |
1818 | i >= 0; i--) | |
1819 | if ((needed[(regno + i) / REGSET_ELT_BITS] | |
1820 | & 1 << ((regno + i) % REGSET_ELT_BITS)) == 0) | |
1821 | REG_NOTES (insn) | |
1822 | = gen_rtx (EXPR_LIST, REG_UNUSED, | |
1823 | gen_rtx (REG, word_mode, regno + i), | |
1824 | REG_NOTES (insn)); | |
1825 | } | |
1826 | } | |
1827 | } | |
1828 | ||
1829 | /* If this is the last pass and this is a SCRATCH, show it will be dying | |
1830 | here and count it. */ | |
1831 | else if (GET_CODE (reg) == SCRATCH && insn != 0) | |
1832 | { | |
1833 | REG_NOTES (insn) | |
1834 | = gen_rtx (EXPR_LIST, REG_UNUSED, reg, REG_NOTES (insn)); | |
1835 | num_scratch++; | |
1836 | } | |
1837 | } | |
1838 | \f | |
1839 | #ifdef AUTO_INC_DEC | |
1840 | ||
1841 | /* X is a MEM found in INSN. See if we can convert it into an auto-increment | |
1842 | reference. */ | |
1843 | ||
1844 | static void | |
1845 | find_auto_inc (needed, x, insn) | |
1846 | regset needed; | |
1847 | rtx x; | |
1848 | rtx insn; | |
1849 | { | |
1850 | rtx addr = XEXP (x, 0); | |
1851 | int offset = 0; | |
1852 | ||
1853 | /* Here we detect use of an index register which might be good for | |
1854 | postincrement, postdecrement, preincrement, or predecrement. */ | |
1855 | ||
1856 | if (GET_CODE (addr) == PLUS && GET_CODE (XEXP (addr, 1)) == CONST_INT) | |
1857 | offset = INTVAL (XEXP (addr, 1)), addr = XEXP (addr, 0); | |
1858 | ||
1859 | if (GET_CODE (addr) == REG) | |
1860 | { | |
1861 | register rtx y; | |
1862 | register int size = GET_MODE_SIZE (GET_MODE (x)); | |
1863 | rtx use; | |
1864 | rtx incr; | |
1865 | int regno = REGNO (addr); | |
1866 | ||
1867 | /* Is the next use an increment that might make auto-increment? */ | |
1868 | incr = reg_next_use[regno]; | |
1869 | if (incr && GET_CODE (PATTERN (incr)) == SET | |
1870 | && BLOCK_NUM (incr) == BLOCK_NUM (insn) | |
1871 | /* Can't add side effects to jumps; if reg is spilled and | |
1872 | reloaded, there's no way to store back the altered value. */ | |
1873 | && GET_CODE (insn) != JUMP_INSN | |
1874 | && (y = SET_SRC (PATTERN (incr)), GET_CODE (y) == PLUS) | |
1875 | && XEXP (y, 0) == addr | |
1876 | && GET_CODE (XEXP (y, 1)) == CONST_INT | |
1877 | && (0 | |
1878 | #ifdef HAVE_POST_INCREMENT | |
1879 | || (INTVAL (XEXP (y, 1)) == size && offset == 0) | |
1880 | #endif | |
1881 | #ifdef HAVE_POST_DECREMENT | |
1882 | || (INTVAL (XEXP (y, 1)) == - size && offset == 0) | |
1883 | #endif | |
1884 | #ifdef HAVE_PRE_INCREMENT | |
1885 | || (INTVAL (XEXP (y, 1)) == size && offset == size) | |
1886 | #endif | |
1887 | #ifdef HAVE_PRE_DECREMENT | |
1888 | || (INTVAL (XEXP (y, 1)) == - size && offset == - size) | |
1889 | #endif | |
1890 | ) | |
1891 | /* Make sure this reg appears only once in this insn. */ | |
1892 | && (use = find_use_as_address (PATTERN (insn), addr, offset), | |
1893 | use != 0 && use != (rtx) 1)) | |
1894 | { | |
1895 | int win = 0; | |
1896 | rtx q = SET_DEST (PATTERN (incr)); | |
1897 | ||
1898 | if (dead_or_set_p (incr, addr)) | |
1899 | win = 1; | |
1900 | else if (GET_CODE (q) == REG && ! reg_used_between_p (q, insn, incr)) | |
1901 | { | |
1902 | /* We have *p followed by q = p+size. | |
1903 | Both p and q must be live afterward, | |
1904 | and q must be dead before. | |
1905 | Change it to q = p, ...*q..., q = q+size. | |
1906 | Then fall into the usual case. */ | |
1907 | rtx insns, temp; | |
1908 | ||
1909 | start_sequence (); | |
1910 | emit_move_insn (q, addr); | |
1911 | insns = get_insns (); | |
1912 | end_sequence (); | |
1913 | ||
1914 | /* If anything in INSNS have UID's that don't fit within the | |
1915 | extra space we allocate earlier, we can't make this auto-inc. | |
1916 | This should never happen. */ | |
1917 | for (temp = insns; temp; temp = NEXT_INSN (temp)) | |
1918 | { | |
1919 | if (INSN_UID (temp) > max_uid_for_flow) | |
1920 | return; | |
1921 | BLOCK_NUM (temp) = BLOCK_NUM (insn); | |
1922 | } | |
1923 | ||
1924 | emit_insns_before (insns, insn); | |
e8b641a1 RK |
1925 | |
1926 | if (basic_block_head[BLOCK_NUM (insn)] == insn) | |
1927 | basic_block_head[BLOCK_NUM (insn)] = insns; | |
1928 | ||
d7429b6a RK |
1929 | XEXP (x, 0) = q; |
1930 | XEXP (y, 0) = q; | |
1931 | ||
1932 | /* INCR will become a NOTE and INSN won't contain a | |
1933 | use of ADDR. If a use of ADDR was just placed in | |
1934 | the insn before INSN, make that the next use. | |
1935 | Otherwise, invalidate it. */ | |
1936 | if (GET_CODE (PREV_INSN (insn)) == INSN | |
1937 | && GET_CODE (PATTERN (PREV_INSN (insn))) == SET | |
1938 | && SET_SRC (PATTERN (PREV_INSN (insn))) == addr) | |
1939 | reg_next_use[regno] = PREV_INSN (insn); | |
1940 | else | |
1941 | reg_next_use[regno] = 0; | |
1942 | ||
1943 | addr = q; | |
1944 | regno = REGNO (q); | |
1945 | win = 1; | |
1946 | ||
1947 | /* REGNO is now used in INCR which is below INSN, but | |
1948 | it previously wasn't live here. If we don't mark | |
1949 | it as needed, we'll put a REG_DEAD note for it | |
1950 | on this insn, which is incorrect. */ | |
1951 | needed[regno / REGSET_ELT_BITS] | |
1952 | |= 1 << (regno % REGSET_ELT_BITS); | |
1953 | ||
1954 | /* If there are any calls between INSN and INCR, show | |
1955 | that REGNO now crosses them. */ | |
1956 | for (temp = insn; temp != incr; temp = NEXT_INSN (temp)) | |
1957 | if (GET_CODE (temp) == CALL_INSN) | |
1958 | reg_n_calls_crossed[regno]++; | |
1959 | } | |
1960 | ||
1961 | if (win) | |
1962 | { | |
1963 | /* We have found a suitable auto-increment: do POST_INC around | |
1964 | the register here, and patch out the increment instruction | |
1965 | that follows. */ | |
1966 | XEXP (x, 0) = gen_rtx ((INTVAL (XEXP (y, 1)) == size | |
1967 | ? (offset ? PRE_INC : POST_INC) | |
1968 | : (offset ? PRE_DEC : POST_DEC)), | |
1969 | Pmode, addr); | |
1970 | ||
1971 | /* Record that this insn has an implicit side effect. */ | |
1972 | REG_NOTES (insn) | |
1973 | = gen_rtx (EXPR_LIST, REG_INC, addr, REG_NOTES (insn)); | |
1974 | ||
1975 | /* Modify the old increment-insn to simply copy | |
1976 | the already-incremented value of our register. */ | |
1977 | SET_SRC (PATTERN (incr)) = addr; | |
1978 | /* Indicate insn must be re-recognized. */ | |
1979 | INSN_CODE (incr) = -1; | |
1980 | ||
1981 | /* If that makes it a no-op (copying the register into itself) | |
1982 | then delete it so it won't appear to be a "use" and a "set" | |
1983 | of this register. */ | |
1984 | if (SET_DEST (PATTERN (incr)) == addr) | |
1985 | { | |
1986 | PUT_CODE (incr, NOTE); | |
1987 | NOTE_LINE_NUMBER (incr) = NOTE_INSN_DELETED; | |
1988 | NOTE_SOURCE_FILE (incr) = 0; | |
1989 | } | |
1990 | ||
1991 | if (regno >= FIRST_PSEUDO_REGISTER) | |
1992 | { | |
1993 | /* Count an extra reference to the reg. When a reg is | |
1994 | incremented, spilling it is worse, so we want to make | |
1995 | that less likely. */ | |
1996 | reg_n_refs[regno] += loop_depth; | |
1997 | /* Count the increment as a setting of the register, | |
1998 | even though it isn't a SET in rtl. */ | |
1999 | reg_n_sets[regno]++; | |
2000 | } | |
2001 | } | |
2002 | } | |
2003 | } | |
2004 | } | |
2005 | #endif /* AUTO_INC_DEC */ | |
2006 | \f | |
2007 | /* Scan expression X and store a 1-bit in LIVE for each reg it uses. | |
2008 | This is done assuming the registers needed from X | |
2009 | are those that have 1-bits in NEEDED. | |
2010 | ||
2011 | On the final pass, FINAL is 1. This means try for autoincrement | |
2012 | and count the uses and deaths of each pseudo-reg. | |
2013 | ||
2014 | INSN is the containing instruction. If INSN is dead, this function is not | |
2015 | called. */ | |
2016 | ||
2017 | static void | |
2018 | mark_used_regs (needed, live, x, final, insn) | |
2019 | regset needed; | |
2020 | regset live; | |
2021 | rtx x; | |
2022 | rtx insn; | |
2023 | int final; | |
2024 | { | |
2025 | register RTX_CODE code; | |
2026 | register int regno; | |
2027 | int i; | |
2028 | ||
2029 | retry: | |
2030 | code = GET_CODE (x); | |
2031 | switch (code) | |
2032 | { | |
2033 | case LABEL_REF: | |
2034 | case SYMBOL_REF: | |
2035 | case CONST_INT: | |
2036 | case CONST: | |
2037 | case CONST_DOUBLE: | |
2038 | case PC: | |
2039 | case CLOBBER: | |
2040 | case ADDR_VEC: | |
2041 | case ADDR_DIFF_VEC: | |
2042 | case ASM_INPUT: | |
2043 | return; | |
2044 | ||
2045 | #ifdef HAVE_cc0 | |
2046 | case CC0: | |
2047 | cc0_live = 1; | |
2048 | return; | |
2049 | #endif | |
2050 | ||
2051 | case MEM: | |
2052 | /* Invalidate the data for the last MEM stored. We could do this only | |
2053 | if the addresses conflict, but this doesn't seem worthwhile. */ | |
2054 | last_mem_set = 0; | |
2055 | ||
2056 | #ifdef AUTO_INC_DEC | |
2057 | if (final) | |
2058 | find_auto_inc (needed, x, insn); | |
2059 | #endif | |
2060 | break; | |
2061 | ||
2062 | case REG: | |
2063 | /* See a register other than being set | |
2064 | => mark it as needed. */ | |
2065 | ||
2066 | regno = REGNO (x); | |
2067 | { | |
2068 | register int offset = regno / REGSET_ELT_BITS; | |
2069 | register int bit = 1 << (regno % REGSET_ELT_BITS); | |
2070 | int all_needed = (needed[offset] & bit) != 0; | |
2071 | int some_needed = (needed[offset] & bit) != 0; | |
2072 | ||
2073 | live[offset] |= bit; | |
2074 | /* A hard reg in a wide mode may really be multiple registers. | |
2075 | If so, mark all of them just like the first. */ | |
2076 | if (regno < FIRST_PSEUDO_REGISTER) | |
2077 | { | |
2078 | int n; | |
2079 | ||
2080 | /* For stack ptr or arg pointer, | |
2081 | nothing below can be necessary, so waste no more time. */ | |
2082 | if (regno == STACK_POINTER_REGNUM | |
2083 | || regno == ARG_POINTER_REGNUM | |
2084 | || regno == FRAME_POINTER_REGNUM) | |
2085 | { | |
2086 | /* If this is a register we are going to try to eliminate, | |
2087 | don't mark it live here. If we are successful in | |
2088 | eliminating it, it need not be live unless it is used for | |
2089 | pseudos, in which case it will have been set live when | |
2090 | it was allocated to the pseudos. If the register will not | |
2091 | be eliminated, reload will set it live at that point. */ | |
2092 | ||
2093 | if (! TEST_HARD_REG_BIT (elim_reg_set, regno)) | |
2094 | regs_ever_live[regno] = 1; | |
2095 | return; | |
2096 | } | |
2097 | /* No death notes for global register variables; | |
2098 | their values are live after this function exits. */ | |
2099 | if (global_regs[regno]) | |
2100 | return; | |
2101 | ||
2102 | n = HARD_REGNO_NREGS (regno, GET_MODE (x)); | |
2103 | while (--n > 0) | |
2104 | { | |
2105 | live[(regno + n) / REGSET_ELT_BITS] | |
2106 | |= 1 << ((regno + n) % REGSET_ELT_BITS); | |
2107 | some_needed |= (needed[(regno + n) / REGSET_ELT_BITS] | |
2108 | & 1 << ((regno + n) % REGSET_ELT_BITS)); | |
2109 | all_needed &= (needed[(regno + n) / REGSET_ELT_BITS] | |
2110 | & 1 << ((regno + n) % REGSET_ELT_BITS)); | |
2111 | } | |
2112 | } | |
2113 | if (final) | |
2114 | { | |
2115 | /* Record where each reg is used, so when the reg | |
2116 | is set we know the next insn that uses it. */ | |
2117 | ||
2118 | reg_next_use[regno] = insn; | |
2119 | ||
2120 | if (regno < FIRST_PSEUDO_REGISTER) | |
2121 | { | |
2122 | /* If a hard reg is being used, | |
2123 | record that this function does use it. */ | |
2124 | ||
2125 | i = HARD_REGNO_NREGS (regno, GET_MODE (x)); | |
2126 | if (i == 0) | |
2127 | i = 1; | |
2128 | do | |
2129 | regs_ever_live[regno + --i] = 1; | |
2130 | while (i > 0); | |
2131 | } | |
2132 | else | |
2133 | { | |
2134 | /* Keep track of which basic block each reg appears in. */ | |
2135 | ||
2136 | register int blocknum = BLOCK_NUM (insn); | |
2137 | ||
2138 | if (reg_basic_block[regno] == REG_BLOCK_UNKNOWN) | |
2139 | reg_basic_block[regno] = blocknum; | |
2140 | else if (reg_basic_block[regno] != blocknum) | |
2141 | reg_basic_block[regno] = REG_BLOCK_GLOBAL; | |
2142 | ||
2143 | /* Count (weighted) number of uses of each reg. */ | |
2144 | ||
2145 | reg_n_refs[regno] += loop_depth; | |
2146 | } | |
2147 | ||
2148 | /* Record and count the insns in which a reg dies. | |
2149 | If it is used in this insn and was dead below the insn | |
2150 | then it dies in this insn. If it was set in this insn, | |
2151 | we do not make a REG_DEAD note; likewise if we already | |
2152 | made such a note. */ | |
2153 | ||
2154 | if (! all_needed | |
2155 | && ! dead_or_set_p (insn, x) | |
2156 | #if 0 | |
2157 | && (regno >= FIRST_PSEUDO_REGISTER || ! fixed_regs[regno]) | |
2158 | #endif | |
2159 | ) | |
2160 | { | |
2161 | /* If none of the words in X is needed, make a REG_DEAD | |
2162 | note. Otherwise, we must make partial REG_DEAD notes. */ | |
2163 | if (! some_needed) | |
2164 | { | |
2165 | REG_NOTES (insn) | |
2166 | = gen_rtx (EXPR_LIST, REG_DEAD, x, REG_NOTES (insn)); | |
2167 | reg_n_deaths[regno]++; | |
2168 | } | |
2169 | else | |
2170 | { | |
2171 | int i; | |
2172 | ||
2173 | /* Don't make a REG_DEAD note for a part of a register | |
2174 | that is set in the insn. */ | |
2175 | ||
2176 | for (i = HARD_REGNO_NREGS (regno, GET_MODE (x)) - 1; | |
2177 | i >= 0; i--) | |
2178 | if ((needed[(regno + i) / REGSET_ELT_BITS] | |
2179 | & 1 << ((regno + i) % REGSET_ELT_BITS)) == 0 | |
2180 | && ! dead_or_set_regno_p (insn, regno + i)) | |
2181 | REG_NOTES (insn) | |
2182 | = gen_rtx (EXPR_LIST, REG_DEAD, | |
2183 | gen_rtx (REG, word_mode, regno + i), | |
2184 | REG_NOTES (insn)); | |
2185 | } | |
2186 | } | |
2187 | } | |
2188 | } | |
2189 | return; | |
2190 | ||
2191 | case SET: | |
2192 | { | |
2193 | register rtx testreg = SET_DEST (x); | |
2194 | int mark_dest = 0; | |
2195 | ||
2196 | /* If storing into MEM, don't show it as being used. But do | |
2197 | show the address as being used. */ | |
2198 | if (GET_CODE (testreg) == MEM) | |
2199 | { | |
2200 | #ifdef AUTO_INC_DEC | |
2201 | if (final) | |
2202 | find_auto_inc (needed, testreg, insn); | |
2203 | #endif | |
2204 | mark_used_regs (needed, live, XEXP (testreg, 0), final, insn); | |
2205 | mark_used_regs (needed, live, SET_SRC (x), final, insn); | |
2206 | return; | |
2207 | } | |
2208 | ||
2209 | /* Storing in STRICT_LOW_PART is like storing in a reg | |
2210 | in that this SET might be dead, so ignore it in TESTREG. | |
2211 | but in some other ways it is like using the reg. | |
2212 | ||
2213 | Storing in a SUBREG or a bit field is like storing the entire | |
2214 | register in that if the register's value is not used | |
2215 | then this SET is not needed. */ | |
2216 | while (GET_CODE (testreg) == STRICT_LOW_PART | |
2217 | || GET_CODE (testreg) == ZERO_EXTRACT | |
2218 | || GET_CODE (testreg) == SIGN_EXTRACT | |
2219 | || GET_CODE (testreg) == SUBREG) | |
2220 | { | |
2221 | /* Modifying a single register in an alternate mode | |
2222 | does not use any of the old value. But these other | |
2223 | ways of storing in a register do use the old value. */ | |
2224 | if (GET_CODE (testreg) == SUBREG | |
2225 | && !(REG_SIZE (SUBREG_REG (testreg)) > REG_SIZE (testreg))) | |
2226 | ; | |
2227 | else | |
2228 | mark_dest = 1; | |
2229 | ||
2230 | testreg = XEXP (testreg, 0); | |
2231 | } | |
2232 | ||
2233 | /* If this is a store into a register, | |
2234 | recursively scan the value being stored. */ | |
2235 | ||
2236 | if (GET_CODE (testreg) == REG | |
2237 | && (regno = REGNO (testreg), regno != FRAME_POINTER_REGNUM) | |
2238 | && regno != ARG_POINTER_REGNUM | |
2239 | && ! (regno < FIRST_PSEUDO_REGISTER && global_regs[regno])) | |
2240 | { | |
2241 | mark_used_regs (needed, live, SET_SRC (x), final, insn); | |
2242 | if (mark_dest) | |
2243 | mark_used_regs (needed, live, SET_DEST (x), final, insn); | |
2244 | return; | |
2245 | } | |
2246 | } | |
2247 | break; | |
2248 | ||
2249 | case RETURN: | |
2250 | /* If exiting needs the right stack value, consider this insn as | |
2251 | using the stack pointer. In any event, consider it as using | |
2252 | all global registers. */ | |
2253 | ||
2254 | #ifdef EXIT_IGNORE_STACK | |
2255 | if (! EXIT_IGNORE_STACK | |
2256 | || (! FRAME_POINTER_REQUIRED && flag_omit_frame_pointer)) | |
2257 | #endif | |
2258 | live[STACK_POINTER_REGNUM / REGSET_ELT_BITS] | |
2259 | |= 1 << (STACK_POINTER_REGNUM % REGSET_ELT_BITS); | |
2260 | ||
2261 | for (i = 0; i < FIRST_PSEUDO_REGISTER; i++) | |
2262 | if (global_regs[i]) | |
2263 | live[i / REGSET_ELT_BITS] |= 1 << (i % REGSET_ELT_BITS); | |
2264 | break; | |
2265 | } | |
2266 | ||
2267 | /* Recursively scan the operands of this expression. */ | |
2268 | ||
2269 | { | |
2270 | register char *fmt = GET_RTX_FORMAT (code); | |
2271 | register int i; | |
2272 | ||
2273 | for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--) | |
2274 | { | |
2275 | if (fmt[i] == 'e') | |
2276 | { | |
2277 | /* Tail recursive case: save a function call level. */ | |
2278 | if (i == 0) | |
2279 | { | |
2280 | x = XEXP (x, 0); | |
2281 | goto retry; | |
2282 | } | |
2283 | mark_used_regs (needed, live, XEXP (x, i), final, insn); | |
2284 | } | |
2285 | else if (fmt[i] == 'E') | |
2286 | { | |
2287 | register int j; | |
2288 | for (j = 0; j < XVECLEN (x, i); j++) | |
2289 | mark_used_regs (needed, live, XVECEXP (x, i, j), final, insn); | |
2290 | } | |
2291 | } | |
2292 | } | |
2293 | } | |
2294 | \f | |
2295 | #ifdef AUTO_INC_DEC | |
2296 | ||
2297 | static int | |
2298 | try_pre_increment_1 (insn) | |
2299 | rtx insn; | |
2300 | { | |
2301 | /* Find the next use of this reg. If in same basic block, | |
2302 | make it do pre-increment or pre-decrement if appropriate. */ | |
2303 | rtx x = PATTERN (insn); | |
2304 | int amount = ((GET_CODE (SET_SRC (x)) == PLUS ? 1 : -1) | |
2305 | * INTVAL (XEXP (SET_SRC (x), 1))); | |
2306 | int regno = REGNO (SET_DEST (x)); | |
2307 | rtx y = reg_next_use[regno]; | |
2308 | if (y != 0 | |
2309 | && BLOCK_NUM (y) == BLOCK_NUM (insn) | |
2310 | && try_pre_increment (y, SET_DEST (PATTERN (insn)), | |
2311 | amount)) | |
2312 | { | |
2313 | /* We have found a suitable auto-increment | |
2314 | and already changed insn Y to do it. | |
2315 | So flush this increment-instruction. */ | |
2316 | PUT_CODE (insn, NOTE); | |
2317 | NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED; | |
2318 | NOTE_SOURCE_FILE (insn) = 0; | |
2319 | /* Count a reference to this reg for the increment | |
2320 | insn we are deleting. When a reg is incremented. | |
2321 | spilling it is worse, so we want to make that | |
2322 | less likely. */ | |
2323 | if (regno >= FIRST_PSEUDO_REGISTER) | |
2324 | { | |
2325 | reg_n_refs[regno] += loop_depth; | |
2326 | reg_n_sets[regno]++; | |
2327 | } | |
2328 | return 1; | |
2329 | } | |
2330 | return 0; | |
2331 | } | |
2332 | ||
2333 | /* Try to change INSN so that it does pre-increment or pre-decrement | |
2334 | addressing on register REG in order to add AMOUNT to REG. | |
2335 | AMOUNT is negative for pre-decrement. | |
2336 | Returns 1 if the change could be made. | |
2337 | This checks all about the validity of the result of modifying INSN. */ | |
2338 | ||
2339 | static int | |
2340 | try_pre_increment (insn, reg, amount) | |
2341 | rtx insn, reg; | |
2342 | int amount; | |
2343 | { | |
2344 | register rtx use; | |
2345 | ||
2346 | /* Nonzero if we can try to make a pre-increment or pre-decrement. | |
2347 | For example, addl $4,r1; movl (r1),... can become movl +(r1),... */ | |
2348 | int pre_ok = 0; | |
2349 | /* Nonzero if we can try to make a post-increment or post-decrement. | |
2350 | For example, addl $4,r1; movl -4(r1),... can become movl (r1)+,... | |
2351 | It is possible for both PRE_OK and POST_OK to be nonzero if the machine | |
2352 | supports both pre-inc and post-inc, or both pre-dec and post-dec. */ | |
2353 | int post_ok = 0; | |
2354 | ||
2355 | /* Nonzero if the opportunity actually requires post-inc or post-dec. */ | |
2356 | int do_post = 0; | |
2357 | ||
2358 | /* From the sign of increment, see which possibilities are conceivable | |
2359 | on this target machine. */ | |
2360 | #ifdef HAVE_PRE_INCREMENT | |
2361 | if (amount > 0) | |
2362 | pre_ok = 1; | |
2363 | #endif | |
2364 | #ifdef HAVE_POST_INCREMENT | |
2365 | if (amount > 0) | |
2366 | post_ok = 1; | |
2367 | #endif | |
2368 | ||
2369 | #ifdef HAVE_PRE_DECREMENT | |
2370 | if (amount < 0) | |
2371 | pre_ok = 1; | |
2372 | #endif | |
2373 | #ifdef HAVE_POST_DECREMENT | |
2374 | if (amount < 0) | |
2375 | post_ok = 1; | |
2376 | #endif | |
2377 | ||
2378 | if (! (pre_ok || post_ok)) | |
2379 | return 0; | |
2380 | ||
2381 | /* It is not safe to add a side effect to a jump insn | |
2382 | because if the incremented register is spilled and must be reloaded | |
2383 | there would be no way to store the incremented value back in memory. */ | |
2384 | ||
2385 | if (GET_CODE (insn) == JUMP_INSN) | |
2386 | return 0; | |
2387 | ||
2388 | use = 0; | |
2389 | if (pre_ok) | |
2390 | use = find_use_as_address (PATTERN (insn), reg, 0); | |
2391 | if (post_ok && (use == 0 || use == (rtx) 1)) | |
2392 | { | |
2393 | use = find_use_as_address (PATTERN (insn), reg, -amount); | |
2394 | do_post = 1; | |
2395 | } | |
2396 | ||
2397 | if (use == 0 || use == (rtx) 1) | |
2398 | return 0; | |
2399 | ||
2400 | if (GET_MODE_SIZE (GET_MODE (use)) != (amount > 0 ? amount : - amount)) | |
2401 | return 0; | |
2402 | ||
2403 | XEXP (use, 0) = gen_rtx (amount > 0 | |
2404 | ? (do_post ? POST_INC : PRE_INC) | |
2405 | : (do_post ? POST_DEC : PRE_DEC), | |
2406 | Pmode, reg); | |
2407 | ||
2408 | /* Record that this insn now has an implicit side effect on X. */ | |
2409 | REG_NOTES (insn) = gen_rtx (EXPR_LIST, REG_INC, reg, REG_NOTES (insn)); | |
2410 | return 1; | |
2411 | } | |
2412 | ||
2413 | #endif /* AUTO_INC_DEC */ | |
2414 | \f | |
2415 | /* Find the place in the rtx X where REG is used as a memory address. | |
2416 | Return the MEM rtx that so uses it. | |
2417 | If PLUSCONST is nonzero, search instead for a memory address equivalent to | |
2418 | (plus REG (const_int PLUSCONST)). | |
2419 | ||
2420 | If such an address does not appear, return 0. | |
2421 | If REG appears more than once, or is used other than in such an address, | |
2422 | return (rtx)1. */ | |
2423 | ||
2424 | static rtx | |
2425 | find_use_as_address (x, reg, plusconst) | |
2426 | register rtx x; | |
2427 | rtx reg; | |
2428 | int plusconst; | |
2429 | { | |
2430 | enum rtx_code code = GET_CODE (x); | |
2431 | char *fmt = GET_RTX_FORMAT (code); | |
2432 | register int i; | |
2433 | register rtx value = 0; | |
2434 | register rtx tem; | |
2435 | ||
2436 | if (code == MEM && XEXP (x, 0) == reg && plusconst == 0) | |
2437 | return x; | |
2438 | ||
2439 | if (code == MEM && GET_CODE (XEXP (x, 0)) == PLUS | |
2440 | && XEXP (XEXP (x, 0), 0) == reg | |
2441 | && GET_CODE (XEXP (XEXP (x, 0), 1)) == CONST_INT | |
2442 | && INTVAL (XEXP (XEXP (x, 0), 1)) == plusconst) | |
2443 | return x; | |
2444 | ||
2445 | if (code == SIGN_EXTRACT || code == ZERO_EXTRACT) | |
2446 | { | |
2447 | /* If REG occurs inside a MEM used in a bit-field reference, | |
2448 | that is unacceptable. */ | |
2449 | if (find_use_as_address (XEXP (x, 0), reg, 0) != 0) | |
2450 | return (rtx) 1; | |
2451 | } | |
2452 | ||
2453 | if (x == reg) | |
2454 | return (rtx) 1; | |
2455 | ||
2456 | for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--) | |
2457 | { | |
2458 | if (fmt[i] == 'e') | |
2459 | { | |
2460 | tem = find_use_as_address (XEXP (x, i), reg, plusconst); | |
2461 | if (value == 0) | |
2462 | value = tem; | |
2463 | else if (tem != 0) | |
2464 | return (rtx) 1; | |
2465 | } | |
2466 | if (fmt[i] == 'E') | |
2467 | { | |
2468 | register int j; | |
2469 | for (j = XVECLEN (x, i) - 1; j >= 0; j--) | |
2470 | { | |
2471 | tem = find_use_as_address (XVECEXP (x, i, j), reg, plusconst); | |
2472 | if (value == 0) | |
2473 | value = tem; | |
2474 | else if (tem != 0) | |
2475 | return (rtx) 1; | |
2476 | } | |
2477 | } | |
2478 | } | |
2479 | ||
2480 | return value; | |
2481 | } | |
2482 | \f | |
2483 | /* Write information about registers and basic blocks into FILE. | |
2484 | This is part of making a debugging dump. */ | |
2485 | ||
2486 | void | |
2487 | dump_flow_info (file) | |
2488 | FILE *file; | |
2489 | { | |
2490 | register int i; | |
2491 | static char *reg_class_names[] = REG_CLASS_NAMES; | |
2492 | ||
2493 | fprintf (file, "%d registers.\n", max_regno); | |
2494 | ||
2495 | for (i = FIRST_PSEUDO_REGISTER; i < max_regno; i++) | |
2496 | if (reg_n_refs[i]) | |
2497 | { | |
2498 | enum reg_class class; | |
2499 | fprintf (file, "\nRegister %d used %d times across %d insns", | |
2500 | i, reg_n_refs[i], reg_live_length[i]); | |
2501 | if (reg_basic_block[i] >= 0) | |
2502 | fprintf (file, " in block %d", reg_basic_block[i]); | |
2503 | if (reg_n_deaths[i] != 1) | |
2504 | fprintf (file, "; dies in %d places", reg_n_deaths[i]); | |
2505 | if (reg_n_calls_crossed[i] == 1) | |
2506 | fprintf (file, "; crosses 1 call"); | |
2507 | else if (reg_n_calls_crossed[i]) | |
2508 | fprintf (file, "; crosses %d calls", reg_n_calls_crossed[i]); | |
2509 | if (PSEUDO_REGNO_BYTES (i) != UNITS_PER_WORD) | |
2510 | fprintf (file, "; %d bytes", PSEUDO_REGNO_BYTES (i)); | |
2511 | class = reg_preferred_class (i); | |
2512 | if (class != GENERAL_REGS) | |
2513 | { | |
2514 | if (reg_preferred_or_nothing (i)) | |
2515 | fprintf (file, "; %s or none", reg_class_names[(int) class]); | |
2516 | else | |
2517 | fprintf (file, "; pref %s", reg_class_names[(int) class]); | |
2518 | } | |
2519 | if (REGNO_POINTER_FLAG (i)) | |
2520 | fprintf (file, "; pointer"); | |
2521 | fprintf (file, ".\n"); | |
2522 | } | |
2523 | fprintf (file, "\n%d basic blocks.\n", n_basic_blocks); | |
2524 | for (i = 0; i < n_basic_blocks; i++) | |
2525 | { | |
2526 | register rtx head, jump; | |
2527 | register int regno; | |
2528 | fprintf (file, "\nBasic block %d: first insn %d, last %d.\n", | |
2529 | i, | |
2530 | INSN_UID (basic_block_head[i]), | |
2531 | INSN_UID (basic_block_end[i])); | |
2532 | /* The control flow graph's storage is freed | |
2533 | now when flow_analysis returns. | |
2534 | Don't try to print it if it is gone. */ | |
2535 | if (basic_block_drops_in) | |
2536 | { | |
2537 | fprintf (file, "Reached from blocks: "); | |
2538 | head = basic_block_head[i]; | |
2539 | if (GET_CODE (head) == CODE_LABEL) | |
2540 | for (jump = LABEL_REFS (head); | |
2541 | jump != head; | |
2542 | jump = LABEL_NEXTREF (jump)) | |
2543 | { | |
2544 | register int from_block = BLOCK_NUM (CONTAINING_INSN (jump)); | |
2545 | fprintf (file, " %d", from_block); | |
2546 | } | |
2547 | if (basic_block_drops_in[i]) | |
2548 | fprintf (file, " previous"); | |
2549 | } | |
2550 | fprintf (file, "\nRegisters live at start:"); | |
2551 | for (regno = 0; regno < max_regno; regno++) | |
2552 | { | |
2553 | register int offset = regno / REGSET_ELT_BITS; | |
2554 | register int bit = 1 << (regno % REGSET_ELT_BITS); | |
2555 | if (basic_block_live_at_start[i][offset] & bit) | |
2556 | fprintf (file, " %d", regno); | |
2557 | } | |
2558 | fprintf (file, "\n"); | |
2559 | } | |
2560 | fprintf (file, "\n"); | |
2561 | } |