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1 | /* Infrastructure for tracking user variable locations and values |
2 | throughout compilation. | |
3 | Copyright (C) 2010, 2011, 2012 Free Software Foundation, Inc. | |
4 | Contributed by Alexandre Oliva <aoliva@redhat.com>. | |
5 | ||
6 | This file is part of GCC. | |
7 | ||
8 | GCC is free software; you can redistribute it and/or modify it under | |
9 | the terms of the GNU General Public License as published by the Free | |
10 | Software Foundation; either version 3, or (at your option) any later | |
11 | version. | |
12 | ||
13 | GCC is distributed in the hope that it will be useful, but WITHOUT ANY | |
14 | WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
15 | FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | |
16 | for more details. | |
17 | ||
18 | You should have received a copy of the GNU General Public License | |
19 | along with GCC; see the file COPYING3. If not see | |
20 | <http://www.gnu.org/licenses/>. */ | |
21 | ||
22 | #include "config.h" | |
23 | #include "system.h" | |
24 | #include "coretypes.h" | |
25 | #include "tm.h" | |
26 | #include "rtl.h" | |
27 | #include "valtrack.h" | |
28 | #include "function.h" | |
29 | #include "regs.h" | |
30 | #include "emit-rtl.h" | |
31 | ||
32 | /* Replace auto-increment addressing modes with explicit operations to access | |
33 | the same addresses without modifying the corresponding registers. */ | |
34 | ||
35 | #ifdef AUTO_INC_DEC | |
36 | static rtx | |
37 | cleanup_auto_inc_dec (rtx src, enum machine_mode mem_mode ATTRIBUTE_UNUSED) | |
38 | { | |
39 | rtx x = src; | |
40 | const RTX_CODE code = GET_CODE (x); | |
41 | int i; | |
42 | const char *fmt; | |
43 | ||
44 | switch (code) | |
45 | { | |
46 | case REG: | |
47 | case CONST_INT: | |
48 | case CONST_DOUBLE: | |
49 | case CONST_FIXED: | |
50 | case CONST_VECTOR: | |
51 | case SYMBOL_REF: | |
52 | case CODE_LABEL: | |
53 | case PC: | |
54 | case CC0: | |
55 | case SCRATCH: | |
56 | /* SCRATCH must be shared because they represent distinct values. */ | |
57 | return x; | |
58 | case CLOBBER: | |
59 | if (REG_P (XEXP (x, 0)) && REGNO (XEXP (x, 0)) < FIRST_PSEUDO_REGISTER) | |
60 | return x; | |
61 | break; | |
62 | ||
63 | case CONST: | |
64 | if (shared_const_p (x)) | |
65 | return x; | |
66 | break; | |
67 | ||
68 | case MEM: | |
69 | mem_mode = GET_MODE (x); | |
70 | break; | |
71 | ||
72 | case PRE_INC: | |
73 | case PRE_DEC: | |
74 | gcc_assert (mem_mode != VOIDmode && mem_mode != BLKmode); | |
75 | return gen_rtx_PLUS (GET_MODE (x), | |
76 | cleanup_auto_inc_dec (XEXP (x, 0), mem_mode), | |
77 | GEN_INT (code == PRE_INC | |
78 | ? GET_MODE_SIZE (mem_mode) | |
79 | : -GET_MODE_SIZE (mem_mode))); | |
80 | ||
81 | case POST_INC: | |
82 | case POST_DEC: | |
83 | case PRE_MODIFY: | |
84 | case POST_MODIFY: | |
85 | return cleanup_auto_inc_dec (code == PRE_MODIFY | |
86 | ? XEXP (x, 1) : XEXP (x, 0), | |
87 | mem_mode); | |
88 | ||
89 | default: | |
90 | break; | |
91 | } | |
92 | ||
93 | /* Copy the various flags, fields, and other information. We assume | |
94 | that all fields need copying, and then clear the fields that should | |
95 | not be copied. That is the sensible default behavior, and forces | |
96 | us to explicitly document why we are *not* copying a flag. */ | |
97 | x = shallow_copy_rtx (x); | |
98 | ||
99 | /* We do not copy the USED flag, which is used as a mark bit during | |
100 | walks over the RTL. */ | |
101 | RTX_FLAG (x, used) = 0; | |
102 | ||
103 | /* We do not copy FRAME_RELATED for INSNs. */ | |
104 | if (INSN_P (x)) | |
105 | RTX_FLAG (x, frame_related) = 0; | |
106 | ||
107 | fmt = GET_RTX_FORMAT (code); | |
108 | for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--) | |
109 | if (fmt[i] == 'e') | |
110 | XEXP (x, i) = cleanup_auto_inc_dec (XEXP (x, i), mem_mode); | |
111 | else if (fmt[i] == 'E' || fmt[i] == 'V') | |
112 | { | |
113 | int j; | |
114 | XVEC (x, i) = rtvec_alloc (XVECLEN (x, i)); | |
115 | for (j = 0; j < XVECLEN (x, i); j++) | |
116 | XVECEXP (x, i, j) | |
117 | = cleanup_auto_inc_dec (XVECEXP (src, i, j), mem_mode); | |
118 | } | |
119 | ||
120 | return x; | |
121 | } | |
122 | #endif | |
123 | ||
124 | /* Auxiliary data structure for propagate_for_debug_stmt. */ | |
125 | ||
126 | struct rtx_subst_pair | |
127 | { | |
128 | rtx to; | |
129 | bool adjusted; | |
130 | }; | |
131 | ||
132 | /* DATA points to an rtx_subst_pair. Return the value that should be | |
133 | substituted. */ | |
134 | ||
135 | static rtx | |
136 | propagate_for_debug_subst (rtx from, const_rtx old_rtx, void *data) | |
137 | { | |
138 | struct rtx_subst_pair *pair = (struct rtx_subst_pair *)data; | |
139 | ||
140 | if (!rtx_equal_p (from, old_rtx)) | |
141 | return NULL_RTX; | |
142 | if (!pair->adjusted) | |
143 | { | |
144 | pair->adjusted = true; | |
145 | #ifdef AUTO_INC_DEC | |
146 | pair->to = cleanup_auto_inc_dec (pair->to, VOIDmode); | |
147 | #else | |
148 | pair->to = copy_rtx (pair->to); | |
149 | #endif | |
150 | pair->to = make_compound_operation (pair->to, SET); | |
151 | return pair->to; | |
152 | } | |
153 | return copy_rtx (pair->to); | |
154 | } | |
155 | ||
156 | /* Replace all the occurrences of DEST with SRC in DEBUG_INSNs between INSN | |
157 | and LAST, not including INSN, but including LAST. Also stop at the end | |
158 | of THIS_BASIC_BLOCK. */ | |
159 | ||
160 | void | |
161 | propagate_for_debug (rtx insn, rtx last, rtx dest, rtx src, | |
162 | basic_block this_basic_block) | |
163 | { | |
164 | rtx next, loc, end = NEXT_INSN (BB_END (this_basic_block)); | |
165 | ||
166 | struct rtx_subst_pair p; | |
167 | p.to = src; | |
168 | p.adjusted = false; | |
169 | ||
170 | next = NEXT_INSN (insn); | |
171 | last = NEXT_INSN (last); | |
172 | while (next != last && next != end) | |
173 | { | |
174 | insn = next; | |
175 | next = NEXT_INSN (insn); | |
176 | if (DEBUG_INSN_P (insn)) | |
177 | { | |
178 | loc = simplify_replace_fn_rtx (INSN_VAR_LOCATION_LOC (insn), | |
179 | dest, propagate_for_debug_subst, &p); | |
180 | if (loc == INSN_VAR_LOCATION_LOC (insn)) | |
181 | continue; | |
182 | INSN_VAR_LOCATION_LOC (insn) = loc; | |
183 | df_insn_rescan (insn); | |
184 | } | |
185 | } | |
186 | } | |
187 | ||
188 | /* Initialize DEBUG to an empty list, and clear USED, if given. */ | |
189 | void | |
190 | dead_debug_init (struct dead_debug *debug, bitmap used) | |
191 | { | |
192 | debug->head = NULL; | |
193 | debug->used = used; | |
194 | debug->to_rescan = NULL; | |
195 | if (used) | |
196 | bitmap_clear (used); | |
197 | } | |
198 | ||
199 | /* Reset all debug uses in HEAD, and clear DEBUG->to_rescan bits of | |
200 | each reset insn. DEBUG is not otherwise modified. If HEAD is | |
201 | DEBUG->head, DEBUG->head will be set to NULL at the end. | |
202 | Otherwise, entries from DEBUG->head that pertain to reset insns | |
203 | will be removed, and only then rescanned. */ | |
204 | ||
205 | static void | |
206 | dead_debug_reset_uses (struct dead_debug *debug, struct dead_debug_use *head) | |
207 | { | |
208 | bool got_head = (debug->head == head); | |
209 | bitmap rescan; | |
210 | struct dead_debug_use **tailp = &debug->head; | |
211 | struct dead_debug_use *cur; | |
212 | bitmap_iterator bi; | |
213 | unsigned int uid; | |
214 | ||
215 | if (got_head) | |
216 | rescan = NULL; | |
217 | else | |
218 | rescan = BITMAP_ALLOC (NULL); | |
219 | ||
220 | while (head) | |
221 | { | |
222 | struct dead_debug_use *next = head->next; | |
223 | rtx insn; | |
224 | ||
225 | insn = DF_REF_INSN (head->use); | |
226 | if (!next || DF_REF_INSN (next->use) != insn) | |
227 | { | |
228 | INSN_VAR_LOCATION_LOC (insn) = gen_rtx_UNKNOWN_VAR_LOC (); | |
229 | if (got_head) | |
230 | df_insn_rescan_debug_internal (insn); | |
231 | else | |
232 | bitmap_set_bit (rescan, INSN_UID (insn)); | |
233 | if (debug->to_rescan) | |
234 | bitmap_clear_bit (debug->to_rescan, INSN_UID (insn)); | |
235 | } | |
236 | XDELETE (head); | |
237 | head = next; | |
238 | } | |
239 | ||
240 | if (got_head) | |
241 | { | |
242 | debug->head = NULL; | |
243 | return; | |
244 | } | |
245 | ||
246 | while ((cur = *tailp)) | |
247 | if (bitmap_bit_p (rescan, INSN_UID (DF_REF_INSN (cur->use)))) | |
248 | { | |
249 | *tailp = cur->next; | |
250 | XDELETE (cur); | |
251 | } | |
252 | else | |
253 | tailp = &cur->next; | |
254 | ||
255 | EXECUTE_IF_SET_IN_BITMAP (rescan, 0, uid, bi) | |
256 | { | |
257 | struct df_insn_info *insn_info = DF_INSN_UID_SAFE_GET (uid); | |
258 | if (insn_info) | |
259 | df_insn_rescan_debug_internal (insn_info->insn); | |
260 | } | |
261 | ||
262 | BITMAP_FREE (rescan); | |
263 | } | |
264 | ||
265 | /* Reset all debug insns with pending uses. Release the bitmap in it, | |
266 | unless it is USED. USED must be the same bitmap passed to | |
267 | dead_debug_init. */ | |
268 | void | |
269 | dead_debug_finish (struct dead_debug *debug, bitmap used) | |
270 | { | |
271 | if (debug->used != used) | |
272 | BITMAP_FREE (debug->used); | |
273 | ||
274 | dead_debug_reset_uses (debug, debug->head); | |
275 | ||
276 | if (debug->to_rescan) | |
277 | { | |
278 | bitmap_iterator bi; | |
279 | unsigned int uid; | |
280 | ||
281 | EXECUTE_IF_SET_IN_BITMAP (debug->to_rescan, 0, uid, bi) | |
282 | { | |
283 | struct df_insn_info *insn_info = DF_INSN_UID_SAFE_GET (uid); | |
284 | if (insn_info) | |
285 | df_insn_rescan (insn_info->insn); | |
286 | } | |
287 | BITMAP_FREE (debug->to_rescan); | |
288 | } | |
289 | } | |
290 | ||
291 | /* Add USE to DEBUG. It must be a dead reference to UREGNO in a debug | |
292 | insn. Create a bitmap for DEBUG as needed. */ | |
293 | void | |
294 | dead_debug_add (struct dead_debug *debug, df_ref use, unsigned int uregno) | |
295 | { | |
296 | struct dead_debug_use *newddu = XNEW (struct dead_debug_use); | |
297 | ||
298 | newddu->use = use; | |
299 | newddu->next = debug->head; | |
300 | debug->head = newddu; | |
301 | ||
302 | if (!debug->used) | |
303 | debug->used = BITMAP_ALLOC (NULL); | |
304 | ||
305 | /* ??? If we dealt with split multi-registers below, we should set | |
306 | all registers for the used mode in case of hardware | |
307 | registers. */ | |
308 | bitmap_set_bit (debug->used, uregno); | |
309 | } | |
310 | ||
311 | /* If UREGNO is referenced by any entry in DEBUG, emit a debug insn | |
312 | before or after INSN (depending on WHERE), that binds a debug temp | |
313 | to the widest-mode use of UREGNO, if WHERE is *_WITH_REG, or the | |
314 | value stored in UREGNO by INSN otherwise, and replace all uses of | |
315 | UREGNO in DEBUG with uses of the debug temp. INSN must be where | |
316 | UREGNO dies, if WHERE is *_BEFORE_*, or where it is set otherwise. | |
317 | Return the number of debug insns emitted. */ | |
318 | int | |
319 | dead_debug_insert_temp (struct dead_debug *debug, unsigned int uregno, | |
320 | rtx insn, enum debug_temp_where where) | |
321 | { | |
322 | struct dead_debug_use **tailp = &debug->head; | |
323 | struct dead_debug_use *cur; | |
324 | struct dead_debug_use *uses = NULL; | |
325 | struct dead_debug_use **usesp = &uses; | |
326 | rtx reg = NULL; | |
327 | rtx breg; | |
328 | rtx dval; | |
329 | rtx bind; | |
330 | ||
331 | if (!debug->used || !bitmap_clear_bit (debug->used, uregno)) | |
332 | return 0; | |
333 | ||
334 | /* Move all uses of uregno from debug->head to uses, setting mode to | |
335 | the widest referenced mode. */ | |
336 | while ((cur = *tailp)) | |
337 | { | |
338 | if (DF_REF_REGNO (cur->use) == uregno) | |
339 | { | |
340 | *usesp = cur; | |
341 | usesp = &cur->next; | |
342 | *tailp = cur->next; | |
343 | cur->next = NULL; | |
344 | if (!reg | |
345 | || (GET_MODE_BITSIZE (GET_MODE (reg)) | |
346 | < GET_MODE_BITSIZE (GET_MODE (*DF_REF_REAL_LOC (cur->use))))) | |
347 | reg = *DF_REF_REAL_LOC (cur->use); | |
348 | } | |
349 | else | |
350 | tailp = &(*tailp)->next; | |
351 | } | |
352 | ||
353 | /* We may have dangling bits in debug->used for registers that were part | |
354 | of a multi-register use, one component of which has been reset. */ | |
355 | if (reg == NULL) | |
356 | { | |
357 | gcc_checking_assert (!uses); | |
358 | return 0; | |
359 | } | |
360 | ||
361 | gcc_checking_assert (uses); | |
362 | ||
363 | breg = reg; | |
364 | /* Recover the expression INSN stores in REG. */ | |
365 | if (where == DEBUG_TEMP_BEFORE_WITH_VALUE) | |
366 | { | |
367 | rtx set = single_set (insn); | |
368 | rtx dest, src; | |
369 | ||
370 | if (set) | |
371 | { | |
372 | dest = SET_DEST (set); | |
373 | src = SET_SRC (set); | |
374 | /* Lose if the REG-setting insn is a CALL. */ | |
375 | if (GET_CODE (src) == CALL) | |
376 | { | |
377 | while (uses) | |
378 | { | |
379 | cur = uses->next; | |
380 | XDELETE (uses); | |
381 | uses = cur; | |
382 | } | |
383 | return 0; | |
384 | } | |
385 | } | |
386 | ||
387 | /* ??? Should we try to extract it from a PARALLEL? */ | |
388 | if (!set) | |
389 | breg = NULL; | |
390 | /* Cool, it's the same REG, we can use SRC. */ | |
391 | else if (dest == reg) | |
392 | breg = copy_rtx (src); | |
393 | else if (REG_P (dest)) | |
394 | { | |
395 | /* Hmm... Something's fishy, we should be setting REG here. */ | |
396 | if (REGNO (dest) != REGNO (reg)) | |
397 | breg = NULL; | |
398 | /* If we're not overwriting all the hardware registers that | |
399 | setting REG in its mode would, we won't know what to bind | |
400 | the debug temp to. ??? We could bind the debug_expr to a | |
401 | CONCAT or PARALLEL with the split multi-registers, and | |
402 | replace them as we found the corresponding sets. */ | |
403 | else if (REGNO (reg) < FIRST_PSEUDO_REGISTER | |
404 | && (hard_regno_nregs[REGNO (reg)][GET_MODE (reg)] | |
405 | != hard_regno_nregs[REGNO (reg)][GET_MODE (dest)])) | |
406 | breg = NULL; | |
407 | /* Ok, it's the same (hardware) REG, but with a different | |
408 | mode, so SUBREG it. */ | |
409 | else | |
410 | breg = lowpart_subreg (GET_MODE (reg), copy_rtx (src), | |
411 | GET_MODE (dest)); | |
412 | } | |
413 | else if (GET_CODE (dest) == SUBREG) | |
414 | { | |
415 | /* We should be setting REG here. Lose. */ | |
416 | if (REGNO (SUBREG_REG (dest)) != REGNO (reg)) | |
417 | breg = NULL; | |
418 | /* Lose if we're setting something other than the lowpart of | |
419 | REG. */ | |
420 | else if (!subreg_lowpart_p (dest)) | |
421 | breg = NULL; | |
422 | /* If we're not overwriting all the hardware registers that | |
423 | setting REG in its mode would, we won't know what to bind | |
424 | the debug temp to. */ | |
425 | else if (REGNO (reg) < FIRST_PSEUDO_REGISTER | |
426 | && (hard_regno_nregs[REGNO (reg)][GET_MODE (reg)] | |
427 | != hard_regno_nregs[REGNO (reg)][GET_MODE (dest)])) | |
428 | breg = NULL; | |
429 | /* Yay, we can use SRC, just adjust its mode. */ | |
430 | else | |
431 | breg = lowpart_subreg (GET_MODE (reg), copy_rtx (src), | |
432 | GET_MODE (dest)); | |
433 | } | |
434 | /* Oh well, we're out of luck. */ | |
435 | else | |
436 | breg = NULL; | |
437 | ||
438 | /* We couldn't figure out the value stored in REG, so reset all | |
439 | of its pending debug uses. */ | |
440 | if (!breg) | |
441 | { | |
442 | dead_debug_reset_uses (debug, uses); | |
443 | return 0; | |
444 | } | |
445 | } | |
446 | ||
447 | /* If there's a single (debug) use of an otherwise unused REG, and | |
448 | the debug use is not part of a larger expression, then it | |
449 | probably doesn't make sense to introduce a new debug temp. */ | |
450 | if (where == DEBUG_TEMP_AFTER_WITH_REG && !uses->next) | |
451 | { | |
452 | rtx next = DF_REF_INSN (uses->use); | |
453 | ||
454 | if (DEBUG_INSN_P (next) && reg == INSN_VAR_LOCATION_LOC (next)) | |
455 | { | |
456 | XDELETE (uses); | |
457 | return 0; | |
458 | } | |
459 | } | |
460 | ||
461 | /* Create DEBUG_EXPR (and DEBUG_EXPR_DECL). */ | |
462 | dval = make_debug_expr_from_rtl (reg); | |
463 | ||
464 | /* Emit a debug bind insn before the insn in which reg dies. */ | |
465 | bind = gen_rtx_VAR_LOCATION (GET_MODE (reg), | |
466 | DEBUG_EXPR_TREE_DECL (dval), breg, | |
467 | VAR_INIT_STATUS_INITIALIZED); | |
468 | ||
469 | if (where == DEBUG_TEMP_AFTER_WITH_REG) | |
470 | bind = emit_debug_insn_after (bind, insn); | |
471 | else | |
472 | bind = emit_debug_insn_before (bind, insn); | |
473 | df_insn_rescan (bind); | |
474 | ||
475 | /* Adjust all uses. */ | |
476 | while ((cur = uses)) | |
477 | { | |
478 | if (GET_MODE (*DF_REF_REAL_LOC (cur->use)) == GET_MODE (reg)) | |
479 | *DF_REF_REAL_LOC (cur->use) = dval; | |
480 | else | |
481 | *DF_REF_REAL_LOC (cur->use) | |
482 | = gen_lowpart_SUBREG (GET_MODE (*DF_REF_REAL_LOC (cur->use)), dval); | |
483 | /* ??? Should we simplify subreg of subreg? */ | |
484 | if (debug->to_rescan == NULL) | |
485 | debug->to_rescan = BITMAP_ALLOC (NULL); | |
486 | bitmap_set_bit (debug->to_rescan, INSN_UID (DF_REF_INSN (cur->use))); | |
487 | uses = cur->next; | |
488 | XDELETE (cur); | |
489 | } | |
490 | ||
491 | return 1; | |
492 | } |