1 /* Scanning of rtl for dataflow analysis.
2 Copyright (C) 2007-2020 Free Software Foundation, Inc.
3 Contributed by Kenneth Zadeck (zadeck@naturalbridge.com).
4
5 This file is part of GCC.
6
7 GCC is free software; you can redistribute it and/or modify it under
8 the terms of the GNU General Public License as published by the Free
9 Software Foundation; either version 3, or (at your option) any later
10 version.
11
12 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
13 WARRANTY; without even the implied warranty of MERCHANTABILITY or
14 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
15 for more details.
16
17 You should have received a copy of the GNU General Public License
18 along with GCC; see the file COPYING3. If not see
19 <http://www.gnu.org/licenses/>. */
20
21
22 #include "config.h"
23 #include "system.h"
24 #include "coretypes.h"
25 #include "backend.h"
26 #include "rtl.h"
27 #include "predict.h"
28 #include "df.h"
29 #include "regs.h"
30
31
32 struct regstat_n_sets_and_refs_t *regstat_n_sets_and_refs;
33
34 /*----------------------------------------------------------------------------
35 REG_N_SETS and REG_N_REFS.
36 ----------------------------------------------------------------------------*/
37
38 /* If a pass need to change these values in some magical way or the
39 pass needs to have accurate values for these and is not using
40 incremental df scanning, then it should use REG_N_SETS and
41 REG_N_USES. If the pass is doing incremental scanning then it
42 should be getting the info from DF_REG_DEF_COUNT and
43 DF_REG_USE_COUNT. */
44
45 void
regstat_init_n_sets_and_refs(void)46 regstat_init_n_sets_and_refs (void)
47 {
48 unsigned int i;
49 unsigned int max_regno = max_reg_num ();
50
51 timevar_push (TV_REG_STATS);
52 df_grow_reg_info ();
53 gcc_assert (!regstat_n_sets_and_refs);
54
55 regstat_n_sets_and_refs = XNEWVEC (struct regstat_n_sets_and_refs_t, max_regno);
56
57 if (MAY_HAVE_DEBUG_BIND_INSNS)
58 for (i = 0; i < max_regno; i++)
59 {
60 int use_count;
61 df_ref use;
62
63 use_count = DF_REG_USE_COUNT (i);
64 for (use = DF_REG_USE_CHAIN (i); use; use = DF_REF_NEXT_REG (use))
65 if (DF_REF_INSN_INFO (use) && DEBUG_INSN_P (DF_REF_INSN (use)))
66 use_count--;
67
68
69 SET_REG_N_SETS (i, DF_REG_DEF_COUNT (i));
70 SET_REG_N_REFS (i, use_count + REG_N_SETS (i));
71 }
72 else
73 for (i = 0; i < max_regno; i++)
74 {
75 SET_REG_N_SETS (i, DF_REG_DEF_COUNT (i));
76 SET_REG_N_REFS (i, DF_REG_USE_COUNT (i) + REG_N_SETS (i));
77 }
78 timevar_pop (TV_REG_STATS);
79
80 }
81
82
83 /* Free the array that holds the REG_N_SETS and REG_N_REFS. */
84
85 void
regstat_free_n_sets_and_refs(void)86 regstat_free_n_sets_and_refs (void)
87 {
88 gcc_assert (regstat_n_sets_and_refs);
89 free (regstat_n_sets_and_refs);
90 regstat_n_sets_and_refs = NULL;
91 }
92
93
94 /*----------------------------------------------------------------------------
95 REGISTER INFORMATION
96
97 Process REG_N_DEATHS, REG_N_CALLS_CROSSED, and REG_BASIC_BLOCK.
98
99 ----------------------------------------------------------------------------*/
100
101 static bitmap setjmp_crosses;
102 struct reg_info_t *reg_info_p;
103
104 /* The number allocated elements of reg_info_p. */
105 size_t reg_info_p_size;
106
107 /* Compute register info: lifetime, bb, and number of defs and uses
108 for basic block BB. LIVE is a scratch bitvector used here. */
109
110 static void
regstat_bb_compute_ri(basic_block bb,bitmap live)111 regstat_bb_compute_ri (basic_block bb, bitmap live)
112 {
113 rtx_insn *insn;
114 df_ref def, use;
115 bitmap_iterator bi;
116 unsigned int regno;
117
118 bitmap_copy (live, df_get_live_out (bb));
119
120 /* Process the regs live at the end of the block. Mark them as
121 not local to any one basic block. */
122 EXECUTE_IF_SET_IN_BITMAP (live, 0, regno, bi)
123 REG_BASIC_BLOCK (regno) = REG_BLOCK_GLOBAL;
124
125 /* Process the artificial defs and uses at the bottom of the block
126 to begin processing. */
127 FOR_EACH_ARTIFICIAL_DEF (def, bb->index)
128 if ((DF_REF_FLAGS (def) & DF_REF_AT_TOP) == 0)
129 bitmap_clear_bit (live, DF_REF_REGNO (def));
130
131 FOR_EACH_ARTIFICIAL_USE (use, bb->index)
132 if ((DF_REF_FLAGS (use) & DF_REF_AT_TOP) == 0)
133 {
134 regno = DF_REF_REGNO (use);
135 bitmap_set_bit (live, regno);
136 }
137
138 FOR_BB_INSNS_REVERSE (bb, insn)
139 {
140 struct df_insn_info *insn_info = DF_INSN_INFO_GET (insn);
141 bitmap_iterator bi;
142 rtx link;
143
144 if (!NONDEBUG_INSN_P (insn))
145 continue;
146
147 link = REG_NOTES (insn);
148 while (link)
149 {
150 if (REG_NOTE_KIND (link) == REG_DEAD)
151 REG_N_DEATHS (REGNO (XEXP (link, 0)))++;
152 link = XEXP (link, 1);
153 }
154
155 /* Process the defs. */
156 if (CALL_P (insn))
157 {
158 bool set_jump = (find_reg_note (insn, REG_SETJMP, NULL) != NULL);
159 EXECUTE_IF_SET_IN_BITMAP (live, 0, regno, bi)
160 {
161 REG_N_CALLS_CROSSED (regno)++;
162
163 /* We have a problem with any pseudoreg that lives
164 across the setjmp. ANSI says that if a user variable
165 does not change in value between the setjmp and the
166 longjmp, then the longjmp preserves it. This
167 includes longjmp from a place where the pseudo
168 appears dead. (In principle, the value still exists
169 if it is in scope.) If the pseudo goes in a hard
170 reg, some other value may occupy that hard reg where
171 this pseudo is dead, thus clobbering the pseudo.
172 Conclusion: such a pseudo must not go in a hard
173 reg. */
174 if (set_jump)
175 bitmap_set_bit (setjmp_crosses, regno);
176 }
177 }
178
179 /* All of the defs except the return value are some sort of
180 clobber. This code is for the return. */
181 FOR_EACH_INSN_INFO_DEF (def, insn_info)
182 {
183 if ((!CALL_P (insn))
184 || (!(DF_REF_FLAGS (def)
185 & (DF_REF_MUST_CLOBBER | DF_REF_MAY_CLOBBER))))
186 {
187 unsigned int dregno = DF_REF_REGNO (def);
188
189 /* Kill this register if it is not a subreg store or
190 conditional store.
191 ??? This means that any partial store is live from
192 the last use in a basic block to the start of this
193 basic block. */
194 if (!(DF_REF_FLAGS (def)
195 & (DF_REF_PARTIAL | DF_REF_CONDITIONAL)))
196 bitmap_clear_bit (live, dregno);
197
198 if (dregno >= FIRST_PSEUDO_REGISTER)
199 {
200 REG_FREQ (dregno) += REG_FREQ_FROM_BB (bb);
201 REG_FREQ (dregno) =
202 MIN (REG_FREQ (dregno), REG_FREQ_MAX);
203
204 if (REG_BASIC_BLOCK (dregno) == REG_BLOCK_UNKNOWN)
205 REG_BASIC_BLOCK (dregno) = bb->index;
206 else if (REG_BASIC_BLOCK (dregno) != bb->index)
207 REG_BASIC_BLOCK (dregno) = REG_BLOCK_GLOBAL;
208 }
209 }
210 }
211
212 FOR_EACH_INSN_INFO_USE (use, insn_info)
213 {
214 unsigned int uregno = DF_REF_REGNO (use);
215
216 if (uregno >= FIRST_PSEUDO_REGISTER)
217 {
218 REG_FREQ (uregno) += REG_FREQ_FROM_BB (bb);
219 REG_FREQ (uregno) =
220 MIN (REG_FREQ (uregno), REG_FREQ_MAX);
221
222 if (REG_BASIC_BLOCK (uregno) == REG_BLOCK_UNKNOWN)
223 REG_BASIC_BLOCK (uregno) = bb->index;
224 else if (REG_BASIC_BLOCK (uregno) != bb->index)
225 REG_BASIC_BLOCK (uregno) = REG_BLOCK_GLOBAL;
226 }
227 }
228 }
229 }
230
231
232 /* Compute register info: lifetime, bb, and number of defs and uses. */
233 void
regstat_compute_ri(void)234 regstat_compute_ri (void)
235 {
236 basic_block bb;
237 bitmap live = BITMAP_ALLOC (&df_bitmap_obstack);
238 unsigned int regno;
239 bitmap_iterator bi;
240
241 /* Initialize everything. */
242
243 gcc_assert (!reg_info_p);
244
245 timevar_push (TV_REG_STATS);
246 setjmp_crosses = BITMAP_ALLOC (&df_bitmap_obstack);
247 max_regno = max_reg_num ();
248 reg_info_p_size = max_regno;
249 reg_info_p = XCNEWVEC (struct reg_info_t, max_regno);
250
251 FOR_EACH_BB_FN (bb, cfun)
252 {
253 regstat_bb_compute_ri (bb, live);
254 }
255
256 BITMAP_FREE (live);
257
258 /* See the setjmp comment in regstat_bb_compute_ri. */
259 EXECUTE_IF_SET_IN_BITMAP (setjmp_crosses, FIRST_PSEUDO_REGISTER, regno, bi)
260 {
261 REG_BASIC_BLOCK (regno) = REG_BLOCK_UNKNOWN;
262 }
263
264 timevar_pop (TV_REG_STATS);
265 }
266
267
268 /* Free all storage associated with the problem. */
269
270 void
regstat_free_ri(void)271 regstat_free_ri (void)
272 {
273 gcc_assert (reg_info_p);
274 reg_info_p_size = 0;
275 free (reg_info_p);
276 reg_info_p = NULL;
277
278 BITMAP_FREE (setjmp_crosses);
279 }
280
281
282 /* Return a bitmap containing the set of registers that cross a setjmp.
283 The client should not change or delete this bitmap. */
284
285 bitmap
regstat_get_setjmp_crosses(void)286 regstat_get_setjmp_crosses (void)
287 {
288 return setjmp_crosses;
289 }
290
291 /*----------------------------------------------------------------------------
292 Process REG_N_CALLS_CROSSED.
293
294 This is used by sched_deps. A good implementation of sched-deps
295 would really process the blocks directly rather than going through
296 lists of insns. If it did this, it could use the exact regs that
297 cross an individual call rather than using this info that merges
298 the info for all calls.
299
300 ----------------------------------------------------------------------------*/
301
302
303
304 /* Compute calls crossed for BB. Live is a scratch bitvector. */
305
306 static void
regstat_bb_compute_calls_crossed(unsigned int bb_index,bitmap live)307 regstat_bb_compute_calls_crossed (unsigned int bb_index, bitmap live)
308 {
309 basic_block bb = BASIC_BLOCK_FOR_FN (cfun, bb_index);
310 rtx_insn *insn;
311 df_ref def, use;
312
313 bitmap_copy (live, df_get_live_out (bb));
314
315 /* Process the artificial defs and uses at the bottom of the block
316 to begin processing. */
317 FOR_EACH_ARTIFICIAL_DEF (def, bb_index)
318 if ((DF_REF_FLAGS (def) & DF_REF_AT_TOP) == 0)
319 bitmap_clear_bit (live, DF_REF_REGNO (def));
320
321 FOR_EACH_ARTIFICIAL_USE (use, bb_index)
322 if ((DF_REF_FLAGS (use) & DF_REF_AT_TOP) == 0)
323 bitmap_set_bit (live, DF_REF_REGNO (use));
324
325 FOR_BB_INSNS_REVERSE (bb, insn)
326 {
327 if (!NONDEBUG_INSN_P (insn))
328 continue;
329
330 gcc_assert (INSN_UID (insn) < (int) DF_INSN_SIZE ());
331 struct df_insn_info *insn_info = DF_INSN_INFO_GET (insn);
332 unsigned int regno;
333
334 /* Process the defs. */
335 if (CALL_P (insn))
336 {
337 bitmap_iterator bi;
338 EXECUTE_IF_SET_IN_BITMAP (live, 0, regno, bi)
339 {
340 REG_N_CALLS_CROSSED (regno)++;
341 }
342 }
343
344 /* All of the defs except the return value are some sort of
345 clobber. This code is for the return. */
346 FOR_EACH_INSN_INFO_DEF (def, insn_info)
347 {
348 if ((!CALL_P (insn))
349 || (!(DF_REF_FLAGS (def) & (DF_REF_MUST_CLOBBER | DF_REF_MAY_CLOBBER))))
350 {
351 /* Kill this register if it is not a subreg store or conditional store. */
352 if (!(DF_REF_FLAGS (def) & (DF_REF_PARTIAL | DF_REF_CONDITIONAL)))
353 bitmap_clear_bit (live, DF_REF_REGNO (def));
354 }
355 }
356
357 FOR_EACH_INSN_INFO_USE (use, insn_info)
358 bitmap_set_bit (live, DF_REF_REGNO (use));
359 }
360 }
361
362
363 /* Compute register info: lifetime, bb, and number of defs and uses. */
364 void
regstat_compute_calls_crossed(void)365 regstat_compute_calls_crossed (void)
366 {
367 basic_block bb;
368 bitmap live = BITMAP_ALLOC (&df_bitmap_obstack);
369
370 /* Initialize everything. */
371 gcc_assert (!reg_info_p);
372
373 timevar_push (TV_REG_STATS);
374 max_regno = max_reg_num ();
375 reg_info_p_size = max_regno;
376 reg_info_p = XCNEWVEC (struct reg_info_t, max_regno);
377
378 FOR_EACH_BB_FN (bb, cfun)
379 {
380 regstat_bb_compute_calls_crossed (bb->index, live);
381 }
382
383 BITMAP_FREE (live);
384 timevar_pop (TV_REG_STATS);
385 }
386
387
388 /* Free all storage associated with the problem. */
389
390 void
regstat_free_calls_crossed(void)391 regstat_free_calls_crossed (void)
392 {
393 gcc_assert (reg_info_p);
394 reg_info_p_size = 0;
395 free (reg_info_p);
396 reg_info_p = NULL;
397 }
398
399 /* Dump the register info to FILE. */
400
401 void
dump_reg_info(FILE * file)402 dump_reg_info (FILE *file)
403 {
404 unsigned int i, max = max_reg_num ();
405 if (reload_completed)
406 return;
407
408 if (reg_info_p_size < max)
409 max = reg_info_p_size;
410
411 fprintf (file, "%d registers.\n", max);
412 for (i = FIRST_PSEUDO_REGISTER; i < max; i++)
413 {
414 enum reg_class rclass, altclass;
415
416 if (regstat_n_sets_and_refs)
417 fprintf (file, "\nRegister %d used %d times",
418 i, REG_N_REFS (i));
419 else if (df)
420 fprintf (file, "\nRegister %d used %d times",
421 i, DF_REG_USE_COUNT (i) + DF_REG_DEF_COUNT (i));
422
423 if (REG_BASIC_BLOCK (i) >= NUM_FIXED_BLOCKS)
424 fprintf (file, " in block %d", REG_BASIC_BLOCK (i));
425 if (regstat_n_sets_and_refs)
426 fprintf (file, "; set %d time%s", REG_N_SETS (i),
427 (REG_N_SETS (i) == 1) ? "" : "s");
428 else if (df)
429 fprintf (file, "; set %d time%s", DF_REG_DEF_COUNT (i),
430 (DF_REG_DEF_COUNT (i) == 1) ? "" : "s");
431 if (regno_reg_rtx[i] != NULL && REG_USERVAR_P (regno_reg_rtx[i]))
432 fputs ("; user var", file);
433 if (REG_N_DEATHS (i) != 1)
434 fprintf (file, "; dies in %d places", REG_N_DEATHS (i));
435 if (REG_N_CALLS_CROSSED (i) == 1)
436 fputs ("; crosses 1 call", file);
437 else if (REG_N_CALLS_CROSSED (i))
438 fprintf (file, "; crosses %d calls", REG_N_CALLS_CROSSED (i));
439 if (regno_reg_rtx[i] != NULL
440 && maybe_ne (PSEUDO_REGNO_BYTES (i), UNITS_PER_WORD))
441 {
442 fprintf (file, "; ");
443 print_dec (PSEUDO_REGNO_BYTES (i), file, SIGNED);
444 fprintf (file, " bytes");
445 }
446
447 rclass = reg_preferred_class (i);
448 altclass = reg_alternate_class (i);
449 if (rclass != GENERAL_REGS || altclass != ALL_REGS)
450 {
451 if (altclass == ALL_REGS || rclass == ALL_REGS)
452 fprintf (file, "; pref %s", reg_class_names[(int) rclass]);
453 else if (altclass == NO_REGS)
454 fprintf (file, "; %s or none", reg_class_names[(int) rclass]);
455 else
456 fprintf (file, "; pref %s, else %s",
457 reg_class_names[(int) rclass],
458 reg_class_names[(int) altclass]);
459 }
460
461 if (regno_reg_rtx[i] != NULL && REG_POINTER (regno_reg_rtx[i]))
462 fputs ("; pointer", file);
463 fputs (".\n", file);
464 }
465 }
466
467