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15637ed4 RG |
1 | /* Allocate registers for pseudo-registers that span basic blocks. |
2 | Copyright (C) 1987, 1988 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 1, 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 | #include <stdio.h> | |
22 | #include "config.h" | |
23 | #include "rtl.h" | |
24 | #include "flags.h" | |
25 | #include "basic-block.h" | |
26 | #include "hard-reg-set.h" | |
27 | #include "regs.h" | |
28 | #include "insn-config.h" | |
29 | ||
30 | /* This pass of the compiler performs global register allocation. | |
31 | It assigns hard register numbers to all the pseudo registers | |
32 | that were not handled in local_alloc. Assignments are recorded | |
33 | in the vector reg_renumber, not by changing the rtl code. | |
34 | (Such changes are made by final). The entry point is | |
35 | the function global_alloc. | |
36 | ||
37 | After allocation is complete, the reload pass is run as a subroutine | |
38 | of this pass, so that when a pseudo reg loses its hard reg due to | |
39 | spilling it is possible to make a second attempt to find a hard | |
40 | reg for it. The reload pass is independent in other respects | |
41 | and it is run even when stupid register allocation is in use. | |
42 | ||
43 | 1. count the pseudo-registers still needing allocation | |
44 | and assign allocation-numbers (allocnos) to them. | |
45 | Set up tables reg_allocno and allocno_reg to map | |
46 | reg numbers to allocnos and vice versa. | |
47 | max_allocno gets the number of allocnos in use. | |
48 | ||
49 | 2. Allocate a max_allocno by max_allocno conflict bit matrix and clear it. | |
50 | Allocate a max_allocno by FIRST_PSEUDO_REGISTER conflict matrix | |
51 | for conflicts between allocnos and explicit hard register use | |
52 | (which includes use of pseudo-registers allocated by local_alloc). | |
53 | ||
54 | 3. for each basic block | |
55 | walk forward through the block, recording which | |
56 | unallocated registers and which hardware registers are live. | |
57 | Build the conflict matrix between the unallocated registers | |
58 | and another of unallocated registers versus hardware registers. | |
59 | Also record the preferred hardware registers | |
60 | for each unallocated one. | |
61 | ||
62 | 4. Sort a table of the allocnos into order of | |
63 | desirability of the variables. | |
64 | ||
65 | 5. Allocate the variables in that order; each if possible into | |
66 | a preferred register, else into another register. */ | |
67 | \f | |
68 | /* Number of pseudo-registers still requiring allocation | |
69 | (not allocated by local_allocate). */ | |
70 | ||
71 | static int max_allocno; | |
72 | ||
73 | /* Indexed by (pseudo) reg number, gives the allocno, or -1 | |
74 | for pseudo registers already allocated by local_allocate. */ | |
75 | ||
76 | static int *reg_allocno; | |
77 | ||
78 | /* Indexed by allocno, gives the reg number. */ | |
79 | ||
80 | static int *allocno_reg; | |
81 | ||
82 | /* A vector of the integers from 0 to max_allocno-1, | |
83 | sorted in the order of first-to-be-allocated first. */ | |
84 | ||
85 | static int *allocno_order; | |
86 | ||
87 | /* Indexed by an allocno, gives the number of consecutive | |
88 | hard registers needed by that pseudo reg. */ | |
89 | ||
90 | static int *allocno_size; | |
91 | ||
92 | /* max_allocno by max_allocno array of bits, | |
93 | recording whether two allocno's conflict (can't go in the same | |
94 | hardware register). | |
95 | ||
96 | `conflicts' is not symmetric; a conflict between allocno's i and j | |
97 | is recorded either in element i,j or in element j,i. */ | |
98 | ||
99 | static int *conflicts; | |
100 | ||
101 | /* Number of ints require to hold max_allocno bits. | |
102 | This is the length of a row in `conflicts'. */ | |
103 | ||
104 | static int allocno_row_words; | |
105 | ||
106 | /* Two macros to test or store 1 in an element of `conflicts'. */ | |
107 | ||
108 | #define CONFLICTP(I, J) \ | |
109 | (conflicts[(I) * allocno_row_words + (J) / INT_BITS] \ | |
110 | & (1 << ((J) % INT_BITS))) | |
111 | ||
112 | #define SET_CONFLICT(I, J) \ | |
113 | (conflicts[(I) * allocno_row_words + (J) / INT_BITS] \ | |
114 | |= (1 << ((J) % INT_BITS))) | |
115 | ||
116 | /* Set of hard regs currently live (during scan of all insns). */ | |
117 | ||
118 | static HARD_REG_SET hard_regs_live; | |
119 | ||
120 | /* Indexed by N, set of hard regs conflicting with allocno N. */ | |
121 | ||
122 | static HARD_REG_SET *hard_reg_conflicts; | |
123 | ||
124 | /* Indexed by N, set of hard regs preferred by allocno N. | |
125 | This is used to make allocnos go into regs that are copied to or from them, | |
126 | when possible, to reduce register shuffling. */ | |
127 | ||
128 | static HARD_REG_SET *hard_reg_preferences; | |
129 | ||
130 | /* Set of registers that some allocno has a preference for. */ | |
131 | ||
132 | static HARD_REG_SET regs_someone_prefers; | |
133 | ||
134 | /* Set of registers that global-alloc isn't supposed to use. */ | |
135 | ||
136 | static HARD_REG_SET no_global_alloc_regs; | |
137 | ||
138 | /* Test a bit in TABLE, a vector of HARD_REG_SETs, | |
139 | for vector element I, and hard register number J. */ | |
140 | ||
141 | #define REGBITP(TABLE, I, J) TEST_HARD_REG_BIT (TABLE[I], J) | |
142 | ||
143 | /* Set to 1 a bit in a vector of HARD_REG_SETs. Works like REGBITP. */ | |
144 | ||
145 | #define SET_REGBIT(TABLE, I, J) SET_HARD_REG_BIT (TABLE[I], J) | |
146 | ||
147 | /* Bit mask for allocnos live at current point in the scan. */ | |
148 | ||
149 | static int *allocnos_live; | |
150 | ||
151 | #define INT_BITS HOST_BITS_PER_INT | |
152 | ||
153 | /* Test, set or clear bit number I in allocnos_live, | |
154 | a bit vector indexed by allocno. */ | |
155 | ||
156 | #define ALLOCNO_LIVE_P(I) \ | |
157 | (allocnos_live[(I) / INT_BITS] & (1 << ((I) % INT_BITS))) | |
158 | ||
159 | #define SET_ALLOCNO_LIVE(I) \ | |
160 | (allocnos_live[(I) / INT_BITS] |= (1 << ((I) % INT_BITS))) | |
161 | ||
162 | #define CLEAR_ALLOCNO_LIVE(I) \ | |
163 | (allocnos_live[(I) / INT_BITS] &= ~(1 << ((I) % INT_BITS))) | |
164 | ||
165 | /* Record all regs that are set in any one insn. | |
166 | Communication from mark_reg_{store,clobber} and global_conflicts. */ | |
167 | ||
168 | static rtx *regs_set; | |
169 | static int n_regs_set; | |
170 | ||
171 | static int allocno_compare (); | |
172 | static void mark_reg_store (); | |
173 | static void mark_reg_clobber (); | |
174 | static void mark_reg_live_nc (); | |
175 | static void mark_reg_death (); | |
176 | static void dump_conflicts (); | |
177 | static void find_reg (); | |
178 | static void global_conflicts (); | |
179 | static void record_conflicts (); | |
180 | static void set_preference (); | |
181 | \f | |
182 | /* Perform allocation of pseudo-registers not allocated by local_alloc. | |
183 | FILE is a file to output debugging information on, | |
184 | or zero if such output is not desired. */ | |
185 | ||
186 | void | |
187 | global_alloc (file) | |
188 | FILE *file; | |
189 | { | |
190 | register int i; | |
191 | ||
192 | max_allocno = 0; | |
193 | ||
194 | CLEAR_HARD_REG_SET (regs_someone_prefers); | |
195 | ||
196 | /* A machine may have certain hard registers that | |
197 | are safe to use only within a basic block. */ | |
198 | ||
199 | CLEAR_HARD_REG_SET (no_global_alloc_regs); | |
200 | #ifdef OVERLAPPING_REGNO_P | |
201 | for (i = 0; i < FIRST_PSEUDO_REGISTER; i++) | |
202 | if (OVERLAPPING_REGNO_P (i)) | |
203 | SET_HARD_REG_BIT (no_global_alloc_regs, i); | |
204 | #endif | |
205 | ||
206 | /* Establish mappings from register number to allocation number | |
207 | and vice versa. In the process, count the allocnos. */ | |
208 | ||
209 | reg_allocno = (int *) alloca (max_regno * sizeof (int)); | |
210 | ||
211 | for (i = 0; i < FIRST_PSEUDO_REGISTER; i++) | |
212 | reg_allocno[i] = -1; | |
213 | ||
214 | for (i = FIRST_PSEUDO_REGISTER; i < max_regno; i++) | |
215 | /* Note that reg_live_length[i] < 0 indicates a "constant" reg | |
216 | that we are supposed to refrain from putting in a hard reg. | |
217 | -2 means do make an allocno but don't allocate it. */ | |
218 | if (reg_n_refs[i] != 0 && reg_renumber[i] < 0 && reg_live_length[i] != -1) | |
219 | { | |
220 | reg_allocno[i] = max_allocno++; | |
221 | if (reg_live_length[i] == 0) | |
222 | abort (); | |
223 | } | |
224 | else | |
225 | reg_allocno[i] = -1; | |
226 | ||
227 | allocno_reg = (int *) alloca (max_allocno * sizeof (int)); | |
228 | allocno_size = (int *) alloca (max_allocno * sizeof (int)); | |
229 | bzero (allocno_size, max_allocno * sizeof (int)); | |
230 | ||
231 | for (i = FIRST_PSEUDO_REGISTER; i < max_regno; i++) | |
232 | if (reg_allocno[i] >= 0) | |
233 | { | |
234 | allocno_reg[reg_allocno[i]] = i; | |
235 | allocno_size[reg_allocno[i]] = PSEUDO_REGNO_SIZE (i); | |
236 | } | |
237 | ||
238 | /* Allocate the space for the conflict tables. */ | |
239 | ||
240 | hard_reg_conflicts = (HARD_REG_SET *) | |
241 | alloca (max_allocno * sizeof (HARD_REG_SET)); | |
242 | bzero (hard_reg_conflicts, max_allocno * sizeof (HARD_REG_SET)); | |
243 | ||
244 | hard_reg_preferences = (HARD_REG_SET *) | |
245 | alloca (max_allocno * sizeof (HARD_REG_SET)); | |
246 | bzero (hard_reg_preferences, max_allocno * sizeof (HARD_REG_SET)); | |
247 | ||
248 | allocno_row_words = (max_allocno + INT_BITS - 1) / INT_BITS; | |
249 | ||
250 | conflicts = (int *) | |
251 | alloca (max_allocno * allocno_row_words * sizeof (int)); | |
252 | bzero (conflicts, max_allocno * allocno_row_words * sizeof (int)); | |
253 | ||
254 | allocnos_live = (int *) alloca (allocno_row_words * sizeof (int)); | |
255 | ||
256 | /* If there is work to be done (at least one reg to allocate), | |
257 | perform global conflict analysis and allocate the regs. */ | |
258 | ||
259 | if (max_allocno > 0) | |
260 | { | |
261 | /* Scan all the insns and compute the conflicts among allocnos | |
262 | and between allocnos and hard regs. */ | |
263 | ||
264 | global_conflicts (); | |
265 | ||
266 | /* Determine the order to allocate the remaining pseudo registers. */ | |
267 | ||
268 | allocno_order = (int *) alloca (max_allocno * sizeof (int)); | |
269 | for (i = 0; i < max_allocno; i++) | |
270 | allocno_order[i] = i; | |
271 | ||
272 | /* Default the size to 1, since allocno_compare uses it to divide by. */ | |
273 | ||
274 | for (i = 0; i < max_allocno; i++) | |
275 | if (allocno_size[i] == 0) | |
276 | allocno_size[i] = 1; | |
277 | ||
278 | qsort (allocno_order, max_allocno, sizeof (int), allocno_compare); | |
279 | ||
280 | if (file) | |
281 | dump_conflicts (file); | |
282 | ||
283 | /* Try allocating them, one by one, in that order, | |
284 | except for parameters marked with reg_live_length[regno] == -2. */ | |
285 | ||
286 | for (i = 0; i < max_allocno; i++) | |
287 | if (reg_live_length[allocno_reg[allocno_order[i]]] >= 0) | |
288 | { | |
289 | /* If we have more than one register class, | |
290 | first try allocating in the class that is cheapest | |
291 | for this pseudo-reg. If that fails, try any reg. */ | |
292 | if (N_REG_CLASSES > 1) | |
293 | { | |
294 | find_reg (allocno_order[i], 0, 0, 0, | |
295 | hard_reg_preferences[allocno_order[i]]); | |
296 | if (reg_renumber[allocno_reg[allocno_order[i]]] >= 0) | |
297 | continue; | |
298 | } | |
299 | if (!reg_preferred_or_nothing (allocno_reg[allocno_order[i]])) | |
300 | find_reg (allocno_order[i], 0, 1, 0, | |
301 | hard_reg_preferences[allocno_order[i]]); | |
302 | } | |
303 | } | |
304 | ||
305 | /* Do the reloads now while the allocno data still exist, so that we can | |
306 | try to assign new hard regs to any pseudo regs that are spilled. */ | |
307 | ||
308 | if (n_basic_blocks > 0) | |
309 | reload (basic_block_head[0], 1, file); | |
310 | } | |
311 | ||
312 | /* Sort predicate for ordering the allocnos. | |
313 | Returns -1 (1) if *v1 should be allocated before (after) *v2. */ | |
314 | ||
315 | static int | |
316 | allocno_compare (v1, v2) | |
317 | int *v1, *v2; | |
318 | { | |
319 | register int r1 = allocno_reg[*v1]; | |
320 | register int r2 = allocno_reg[*v2]; | |
321 | /* Note that the quotient will never be bigger than | |
322 | the value of floor_log2 times the maximum number of | |
323 | times a register can occur in one insn (surely less than 100). | |
324 | Multiplying this by 10000 can't overflow. */ | |
325 | register int pri1 | |
326 | = (((double) (floor_log2 (reg_n_refs[r1]) * reg_n_refs[r1]) | |
327 | / (reg_live_length[r1] * allocno_size[*v1])) | |
328 | * 10000); | |
329 | register int pri2 | |
330 | = (((double) (floor_log2 (reg_n_refs[r2]) * reg_n_refs[r2]) | |
331 | / (reg_live_length[r2] * allocno_size[*v2])) | |
332 | * 10000); | |
333 | if (pri2 - pri1) | |
334 | return pri2 - pri1; | |
335 | ||
336 | /* If regs are equally good, sort by allocno, | |
337 | so that the results of qsort leave nothing to chance. */ | |
338 | return *v1 - *v2; | |
339 | } | |
340 | \f | |
341 | /* Scan the rtl code and record all conflicts in the conflict matrices. */ | |
342 | ||
343 | static void | |
344 | global_conflicts () | |
345 | { | |
346 | register int b, i; | |
347 | register rtx insn; | |
348 | short *block_start_allocnos; | |
349 | ||
350 | /* Make a vector that mark_reg_{store,clobber} will store in. */ | |
351 | regs_set = (rtx *) alloca (max_parallel * sizeof (rtx) * 2); | |
352 | ||
353 | block_start_allocnos = (short *) alloca (max_allocno * sizeof (short)); | |
354 | ||
355 | for (b = 0; b < n_basic_blocks; b++) | |
356 | { | |
357 | bzero (allocnos_live, allocno_row_words * sizeof (int)); | |
358 | ||
359 | /* Initialize table of registers currently live | |
360 | to the state at the beginning of this basic block. | |
361 | This also marks the conflicts among them. | |
362 | ||
363 | For pseudo-regs, there is only one bit for each one | |
364 | no matter how many hard regs it occupies. | |
365 | This is ok; we know the size from PSEUDO_REGNO_SIZE. | |
366 | For explicit hard regs, we cannot know the size that way | |
367 | since one hard reg can be used with various sizes. | |
368 | Therefore, we must require that all the hard regs | |
369 | implicitly live as part of a multi-word hard reg | |
370 | are explicitly marked in basic_block_live_at_start. */ | |
371 | ||
372 | { | |
373 | register int offset, bit; | |
374 | register regset old = basic_block_live_at_start[b]; | |
375 | int ax = 0; | |
376 | ||
377 | #ifdef HARD_REG_SET | |
378 | hard_regs_live = old[0]; | |
379 | #else | |
380 | COPY_HARD_REG_SET (hard_regs_live, old); | |
381 | #endif | |
382 | for (offset = 0, i = 0; offset < regset_size; offset++) | |
383 | if (old[offset] == 0) | |
384 | i += HOST_BITS_PER_INT; | |
385 | else | |
386 | for (bit = 1; bit; bit <<= 1, i++) | |
387 | { | |
388 | if (i >= max_regno) | |
389 | break; | |
390 | if (old[offset] & bit) | |
391 | { | |
392 | register int a = reg_allocno[i]; | |
393 | if (a >= 0) | |
394 | { | |
395 | SET_ALLOCNO_LIVE (a); | |
396 | block_start_allocnos[ax++] = a; | |
397 | } | |
398 | else if ((a = reg_renumber[i]) >= 0) | |
399 | mark_reg_live_nc (a, PSEUDO_REGNO_MODE (i)); | |
400 | } | |
401 | } | |
402 | ||
403 | /* Record that each allocno now live conflicts with each other | |
404 | allocno now live, and with each hard reg now live. */ | |
405 | ||
406 | record_conflicts (block_start_allocnos, ax); | |
407 | } | |
408 | ||
409 | insn = basic_block_head[b]; | |
410 | ||
411 | /* Scan the code of this basic block, noting which allocnos | |
412 | and hard regs are born or die. When one is born, | |
413 | record a conflict with all others currently live. */ | |
414 | ||
415 | while (1) | |
416 | { | |
417 | register RTX_CODE code = GET_CODE (insn); | |
418 | register rtx link; | |
419 | ||
420 | /* Make regs_set an empty set. */ | |
421 | ||
422 | n_regs_set = 0; | |
423 | ||
424 | if (code == INSN || code == CALL_INSN || code == JUMP_INSN) | |
425 | { | |
426 | /* Mark any registers clobbered by INSN as live, | |
427 | so they conflict with the inputs. */ | |
428 | ||
429 | note_stores (PATTERN (insn), mark_reg_clobber); | |
430 | ||
431 | /* Mark any registers dead after INSN as dead now. */ | |
432 | ||
433 | for (link = REG_NOTES (insn); link; link = XEXP (link, 1)) | |
434 | if (REG_NOTE_KIND (link) == REG_DEAD) | |
435 | mark_reg_death (XEXP (link, 0)); | |
436 | ||
437 | /* Mark any registers set in INSN as live, | |
438 | and mark them as conflicting with all other live regs. | |
439 | Clobbers are processed again, so they conflict with | |
440 | the registers that are set. */ | |
441 | ||
442 | note_stores (PATTERN (insn), mark_reg_store); | |
443 | ||
444 | /* Mark any registers both set and dead after INSN as dead. | |
445 | This is not redundant! | |
446 | A register may be set and killed in the same insn. | |
447 | It is necessary to mark them as live, above, to get | |
448 | the right conflicts within the insn. */ | |
449 | ||
450 | while (n_regs_set > 0) | |
451 | if (find_regno_note (insn, REG_DEAD, REGNO (regs_set[--n_regs_set]))) | |
452 | mark_reg_death (regs_set[n_regs_set]); | |
453 | ||
454 | /* Likewise for regs set by incrementation. */ | |
455 | ||
456 | for (link = REG_NOTES (insn); link; link = XEXP (link, 1)) | |
457 | if (REG_NOTE_KIND (link) == REG_INC | |
458 | && find_regno_note (insn, REG_DEAD, REGNO (XEXP (link, 0)))) | |
459 | mark_reg_death (XEXP (link, 0)); | |
460 | } | |
461 | ||
462 | if (insn == basic_block_end[b]) | |
463 | break; | |
464 | insn = NEXT_INSN (insn); | |
465 | } | |
466 | } | |
467 | } | |
468 | \f | |
469 | /* Assign a hard register to ALLOCNO; look for one that is the beginning | |
470 | of a long enough stretch of hard regs none of which conflicts with ALLOCNO. | |
471 | The registers marked in PREFREGS are tried first. | |
472 | ||
473 | If ALL_REGS_P is zero, consider only the preferred class of ALLOCNO's reg. | |
474 | Otherwise ignore that preferred class. | |
475 | ||
476 | If ACCEPT_CALL_CLOBBERED is nonzero, accept a call-clobbered hard reg that | |
477 | will have to be saved and restored at calls. | |
478 | ||
479 | If we find one, record it in reg_renumber. | |
480 | If not, do nothing. */ | |
481 | ||
482 | static void | |
483 | find_reg (allocno, losers, all_regs_p, accept_call_clobbered, prefregs) | |
484 | int allocno; | |
485 | register short *losers; | |
486 | int all_regs_p; | |
487 | int accept_call_clobbered; | |
488 | HARD_REG_SET prefregs; | |
489 | { | |
490 | register int i, prefreg, pass; | |
491 | #ifdef HARD_REG_SET | |
492 | register /* Declare it register if it's a scalar. */ | |
493 | #endif | |
494 | HARD_REG_SET used; | |
495 | ||
496 | enum reg_class class | |
497 | = all_regs_p ? GENERAL_REGS : reg_preferred_class (allocno_reg[allocno]); | |
498 | enum machine_mode mode = PSEUDO_REGNO_MODE (allocno_reg[allocno]); | |
499 | ||
500 | if (accept_call_clobbered) | |
501 | COPY_HARD_REG_SET (used, call_fixed_reg_set); | |
502 | else if (reg_n_calls_crossed[allocno_reg[allocno]] == 0) | |
503 | COPY_HARD_REG_SET (used, fixed_reg_set); | |
504 | else | |
505 | COPY_HARD_REG_SET (used, call_used_reg_set); | |
506 | ||
507 | /* Some registers should not be allocated in global-alloc. */ | |
508 | IOR_HARD_REG_SET (used, no_global_alloc_regs); | |
509 | ||
510 | IOR_COMPL_HARD_REG_SET (used, reg_class_contents[(int) class]); | |
511 | IOR_HARD_REG_SET (used, hard_reg_conflicts[allocno]); | |
512 | if (frame_pointer_needed) | |
513 | SET_HARD_REG_BIT (used, FRAME_POINTER_REGNUM); | |
514 | ||
515 | AND_COMPL_HARD_REG_SET (prefregs, used); | |
516 | ||
517 | /* Try to find a register from the preferred set first. */ | |
518 | ||
519 | i = -1; | |
520 | for (prefreg = 0; prefreg < FIRST_PSEUDO_REGISTER; prefreg++) | |
521 | if (TEST_HARD_REG_BIT (prefregs, prefreg) | |
522 | && (losers == 0 || losers[prefreg] < 0) | |
523 | && HARD_REGNO_MODE_OK (prefreg, mode)) | |
524 | { | |
525 | register int j; | |
526 | register int lim = prefreg + HARD_REGNO_NREGS (prefreg, mode); | |
527 | for (j = prefreg + 1; | |
528 | (j < lim | |
529 | && ! TEST_HARD_REG_BIT (used, j) | |
530 | && (losers == 0 || losers[j] < 0)); | |
531 | j++); | |
532 | if (j == lim) | |
533 | { | |
534 | i = prefreg; | |
535 | break; | |
536 | } | |
537 | } | |
538 | ||
539 | #if 0 | |
540 | /* Otherwise try each hard reg to see if it fits. Do this in two passes. | |
541 | In the first pass, skip registers that are prefered by some pseudo to | |
542 | give it a better chance of getting one of those registers. Only if | |
543 | we can't get a register when excluding those do we take one of them. */ | |
544 | ||
545 | /* This is turned off because it makes worse allocation on the 68020. */ | |
546 | for (pass = 0; pass <= 1 && i < 0; pass++) | |
547 | #endif | |
548 | pass = 1; | |
549 | for (i = 0; i < FIRST_PSEUDO_REGISTER; i++) | |
550 | { | |
551 | #ifdef REG_ALLOC_ORDER | |
552 | int regno = reg_alloc_order[i]; | |
553 | #else | |
554 | int regno = i; | |
555 | #endif | |
556 | if (! TEST_HARD_REG_BIT (used, regno) | |
557 | && (losers == 0 || losers[regno] < 0) | |
558 | && (pass == 1 || ! TEST_HARD_REG_BIT (regs_someone_prefers, regno)) | |
559 | && HARD_REGNO_MODE_OK (regno, mode)) | |
560 | { | |
561 | register int j; | |
562 | register int lim = regno + HARD_REGNO_NREGS (regno, mode); | |
563 | for (j = regno + 1; | |
564 | (j < lim | |
565 | && ! TEST_HARD_REG_BIT (used, j) | |
566 | && (losers == 0 || losers[j] < 0)); | |
567 | j++); | |
568 | if (j == lim) | |
569 | { | |
570 | i = regno; | |
571 | break; | |
572 | } | |
573 | #ifndef REG_ALLOC_ORDER | |
574 | i = j; /* Skip starting points we know will lose */ | |
575 | #endif | |
576 | } | |
577 | } | |
578 | ||
579 | /* Did we find a register? */ | |
580 | ||
581 | if (i < FIRST_PSEUDO_REGISTER) | |
582 | { | |
583 | register int lim, j; | |
584 | HARD_REG_SET this_reg; | |
585 | ||
586 | /* Yes. Record it as the hard register of this pseudo-reg. */ | |
587 | reg_renumber[allocno_reg[allocno]] = i; | |
588 | /* For each other pseudo-reg conflicting with this one, | |
589 | mark it as conflicting with the hard regs this one occupies. */ | |
590 | CLEAR_HARD_REG_SET (this_reg); | |
591 | lim = i + HARD_REGNO_NREGS (i, mode); | |
592 | for (j = i; j < lim; j++) | |
593 | SET_HARD_REG_BIT (this_reg, j); | |
594 | lim = allocno; | |
595 | for (j = 0; j < max_allocno; j++) | |
596 | if (CONFLICTP (lim, j) || CONFLICTP (j, lim)) | |
597 | { | |
598 | IOR_HARD_REG_SET (hard_reg_conflicts[j], this_reg); | |
599 | } | |
600 | } | |
601 | else if (flag_caller_saves) | |
602 | { | |
603 | /* Did not find a register. If it would be profitable to | |
604 | allocate a call-clobbered register and save and restore it | |
605 | around calls, do that. */ | |
606 | if (! accept_call_clobbered | |
607 | && reg_n_calls_crossed[allocno_reg[allocno]] != 0 | |
608 | && CALLER_SAVE_PROFITABLE (reg_n_refs[allocno_reg[allocno]], | |
609 | reg_n_calls_crossed[allocno_reg[allocno]])) | |
610 | { | |
611 | find_reg (allocno, losers, all_regs_p, 1, prefregs); | |
612 | if (reg_renumber[allocno_reg[allocno]] >= 0) | |
613 | caller_save_needed = 1; | |
614 | } | |
615 | } | |
616 | } | |
617 | \f | |
618 | /* Called from `reload' to look for a hard reg to put pseudo reg REGNO in. | |
619 | Perhaps it had previously seemed not worth a hard reg, | |
620 | or perhaps its old hard reg has been commandeered for reloads. | |
621 | FORBIDDEN_REGS is a vector that indicates certain hard regs | |
622 | that may not be used, even if they do not appear to be allocated. | |
623 | A nonnegative element means the corresponding hard reg is forbidden. | |
624 | If FORBIDDEN_REGS is zero, no regs are forbidden. */ | |
625 | ||
626 | void | |
627 | retry_global_alloc (regno, forbidden_regs) | |
628 | int regno; | |
629 | short *forbidden_regs; | |
630 | { | |
631 | int allocno = reg_allocno[regno]; | |
632 | if (allocno >= 0) | |
633 | { | |
634 | /* If we have more than one register class, | |
635 | first try allocating in the class that is cheapest | |
636 | for this pseudo-reg. If that fails, try any reg. */ | |
637 | if (N_REG_CLASSES > 1) | |
638 | find_reg (allocno, forbidden_regs, 0, 0, | |
639 | hard_reg_preferences[allocno]); | |
640 | if (reg_renumber[regno] < 0 | |
641 | && !reg_preferred_or_nothing (regno)) | |
642 | find_reg (allocno, forbidden_regs, 1, 0, | |
643 | hard_reg_preferences[allocno]); | |
644 | } | |
645 | } | |
646 | ||
647 | /* Called from reload pass to see if current function's pseudo regs | |
648 | require a frame pointer to be allocated and set up. | |
649 | ||
650 | Return 1 if so, 0 otherwise. | |
651 | We may alter the hard-reg allocation of the pseudo regs | |
652 | in order to make the frame pointer unnecessary. | |
653 | However, if the value is 1, nothing has been altered. | |
654 | ||
655 | Args grant access to some tables used in reload1.c. | |
656 | See there for info on them. */ | |
657 | ||
658 | int | |
659 | check_frame_pointer_required (reg_equiv_constant, reg_equiv_mem, reg_equiv_address) | |
660 | rtx *reg_equiv_constant, *reg_equiv_mem, *reg_equiv_address; | |
661 | { | |
662 | register int i; | |
663 | HARD_REG_SET *old_hard_reg_conflicts; | |
664 | short *old_reg_renumber; | |
665 | char old_regs_ever_live[FIRST_PSEUDO_REGISTER]; | |
666 | ||
667 | /* If any pseudo reg has no hard reg and no equivalent, | |
668 | we must have a frame pointer. */ | |
669 | ||
670 | for (i = FIRST_PSEUDO_REGISTER; i < max_regno; i++) | |
671 | if (reg_renumber[i] < 0 && reg_n_refs[i] > 0 | |
672 | && reg_equiv_mem[i] == 0 && reg_equiv_constant[i] == 0 | |
673 | && reg_equiv_address[i] == 0) | |
674 | return 1; | |
675 | ||
676 | /* If we might not need a frame pointer, | |
677 | try finding a hard reg for any pseudo that has a memory equivalent. | |
678 | That is because the memory equivalent probably refers to a frame | |
679 | pointer. */ | |
680 | ||
681 | old_reg_renumber = (short *) alloca (max_regno * sizeof (short)); | |
682 | old_hard_reg_conflicts = (HARD_REG_SET *) | |
683 | alloca (max_allocno * sizeof (HARD_REG_SET)); | |
684 | ||
685 | bcopy (reg_renumber, old_reg_renumber, max_regno * sizeof (short)); | |
686 | bcopy (hard_reg_conflicts, old_hard_reg_conflicts, | |
687 | max_allocno * sizeof (HARD_REG_SET)); | |
688 | bcopy (regs_ever_live, old_regs_ever_live, sizeof regs_ever_live); | |
689 | ||
690 | for (i = FIRST_PSEUDO_REGISTER; i < max_regno; i++) | |
691 | if (reg_renumber[i] < 0 | |
692 | && ((reg_equiv_mem[i] | |
693 | && reg_mentioned_p (frame_pointer_rtx, reg_equiv_mem[i])) | |
694 | || (reg_equiv_address[i] | |
695 | && reg_mentioned_p (frame_pointer_rtx, reg_equiv_address[i])))) | |
696 | { | |
697 | retry_global_alloc (i, 0); | |
698 | /* If we can't find a hard reg for ALL of them, | |
699 | or if a previously unneeded hard reg is used that requires saving, | |
700 | we fail: set all those pseudos back as they were. */ | |
701 | if (reg_renumber[i] < 0 | |
702 | || (! old_regs_ever_live[reg_renumber[i]] | |
703 | && ! call_used_regs[reg_renumber[i]])) | |
704 | { | |
705 | bcopy (old_reg_renumber, reg_renumber, | |
706 | max_regno * sizeof (short)); | |
707 | bcopy (old_hard_reg_conflicts, hard_reg_conflicts, | |
708 | max_allocno * sizeof (HARD_REG_SET)); | |
709 | bcopy (old_regs_ever_live, regs_ever_live, sizeof regs_ever_live); | |
710 | return 1; | |
711 | } | |
712 | mark_home_live (i); | |
713 | } | |
714 | ||
715 | return 0; | |
716 | } | |
717 | \f | |
718 | /* Record a conflict between register REGNO | |
719 | and everything currently live. | |
720 | REGNO must not be a pseudo reg that was allocated | |
721 | by local_alloc; such numbers must be translated through | |
722 | reg_renumber before calling here. */ | |
723 | ||
724 | static void | |
725 | record_one_conflict (regno) | |
726 | int regno; | |
727 | { | |
728 | register int j; | |
729 | ||
730 | if (regno < FIRST_PSEUDO_REGISTER) | |
731 | /* When a hard register becomes live, | |
732 | record conflicts with live pseudo regs. */ | |
733 | for (j = 0; j < max_allocno; j++) | |
734 | { | |
735 | if (ALLOCNO_LIVE_P (j)) | |
736 | SET_HARD_REG_BIT (hard_reg_conflicts[j], regno); | |
737 | } | |
738 | else | |
739 | /* When a pseudo-register becomes live, | |
740 | record conflicts first with hard regs, | |
741 | then with other pseudo regs. */ | |
742 | { | |
743 | register int ialloc = reg_allocno[regno]; | |
744 | register int ialloc_prod = ialloc * allocno_row_words; | |
745 | IOR_HARD_REG_SET (hard_reg_conflicts[ialloc], hard_regs_live); | |
746 | for (j = allocno_row_words - 1; j >= 0; j--) | |
747 | conflicts[ialloc_prod + j] |= allocnos_live[j]; | |
748 | } | |
749 | } | |
750 | ||
751 | /* Record all allocnos currently live as conflicting | |
752 | with each other and with all hard regs currently live. | |
753 | ALLOCNO_VEC is a vector of LEN allocnos, all allocnos that | |
754 | are currently live. Their bits are also flagged in allocnos_live. */ | |
755 | ||
756 | static void | |
757 | record_conflicts (allocno_vec, len) | |
758 | register short *allocno_vec; | |
759 | register int len; | |
760 | { | |
761 | register int allocno; | |
762 | register int j; | |
763 | register int ialloc_prod; | |
764 | ||
765 | while (--len >= 0) | |
766 | { | |
767 | allocno = allocno_vec[len]; | |
768 | ialloc_prod = allocno * allocno_row_words; | |
769 | IOR_HARD_REG_SET (hard_reg_conflicts[allocno], hard_regs_live); | |
770 | for (j = allocno_row_words - 1; j >= 0; j--) | |
771 | conflicts[ialloc_prod + j] |= allocnos_live[j]; | |
772 | } | |
773 | } | |
774 | \f | |
775 | /* Handle the case where REG is set by the insn being scanned, | |
776 | during the forward scan to accumulate conflicts. | |
777 | Store a 1 in regs_live or allocnos_live for this register, record how many | |
778 | consecutive hardware registers it actually needs, | |
779 | and record a conflict with all other registers already live. | |
780 | ||
781 | Note that even if REG does not remain alive after this insn, | |
782 | we must mark it here as live, to ensure a conflict between | |
783 | REG and any other regs set in this insn that really do live. | |
784 | This is because those other regs could be considered after this. | |
785 | ||
786 | REG might actually be something other than a register; | |
787 | if so, we do nothing. | |
788 | ||
789 | CLOBBERs are processed here by calling mark_reg_clobber. */ | |
790 | ||
791 | static void | |
792 | mark_reg_store (orig_reg, setter) | |
793 | rtx orig_reg, setter; | |
794 | { | |
795 | register int regno; | |
796 | register rtx reg = orig_reg; | |
797 | ||
798 | /* WORD is which word of a multi-register group is being stored. | |
799 | For the case where the store is actually into a SUBREG of REG. | |
800 | Except we don't use it; I believe the entire REG needs to be | |
801 | made live. */ | |
802 | int word = 0; | |
803 | ||
804 | if (GET_CODE (reg) == SUBREG) | |
805 | { | |
806 | word = SUBREG_WORD (reg); | |
807 | reg = SUBREG_REG (reg); | |
808 | } | |
809 | ||
810 | if (GET_CODE (reg) != REG) | |
811 | return; | |
812 | ||
813 | if (GET_CODE (setter) != SET) | |
814 | { | |
815 | /* A clobber of a register should be processed here too. */ | |
816 | mark_reg_clobber (orig_reg, setter); | |
817 | return; | |
818 | } | |
819 | ||
820 | regs_set[n_regs_set++] = reg; | |
821 | ||
822 | set_preference (reg, SET_SRC (setter)); | |
823 | ||
824 | regno = REGNO (reg); | |
825 | ||
826 | if (reg_renumber[regno] >= 0) | |
827 | regno = reg_renumber[regno] /* + word */; | |
828 | ||
829 | /* Either this is one of the max_allocno pseudo regs not allocated, | |
830 | or it is or has a hardware reg. First handle the pseudo-regs. */ | |
831 | if (regno >= FIRST_PSEUDO_REGISTER) | |
832 | { | |
833 | if (reg_allocno[regno] >= 0) | |
834 | { | |
835 | SET_ALLOCNO_LIVE (reg_allocno[regno]); | |
836 | record_one_conflict (regno); | |
837 | } | |
838 | } | |
839 | /* Handle hardware regs (and pseudos allocated to hard regs). */ | |
840 | else if (! fixed_regs[regno]) | |
841 | { | |
842 | register int last = regno + HARD_REGNO_NREGS (regno, GET_MODE (reg)); | |
843 | while (regno < last) | |
844 | { | |
845 | record_one_conflict (regno); | |
846 | SET_HARD_REG_BIT (hard_regs_live, regno); | |
847 | regno++; | |
848 | } | |
849 | } | |
850 | } | |
851 | \f | |
852 | /* Like mark_reg_set except notice just CLOBBERs; ignore SETs. */ | |
853 | ||
854 | static void | |
855 | mark_reg_clobber (reg, setter) | |
856 | rtx reg, setter; | |
857 | { | |
858 | register int regno; | |
859 | ||
860 | /* WORD is which word of a multi-register group is being stored. | |
861 | For the case where the store is actually into a SUBREG of REG. | |
862 | Except we don't use it; I believe the entire REG needs to be | |
863 | made live. */ | |
864 | int word = 0; | |
865 | ||
866 | if (GET_CODE (setter) != CLOBBER) | |
867 | return; | |
868 | ||
869 | if (GET_CODE (reg) == SUBREG) | |
870 | { | |
871 | word = SUBREG_WORD (reg); | |
872 | reg = SUBREG_REG (reg); | |
873 | } | |
874 | ||
875 | if (GET_CODE (reg) != REG) | |
876 | return; | |
877 | ||
878 | regs_set[n_regs_set++] = reg; | |
879 | ||
880 | regno = REGNO (reg); | |
881 | ||
882 | if (reg_renumber[regno] >= 0) | |
883 | regno = reg_renumber[regno] /* + word */; | |
884 | ||
885 | /* Either this is one of the max_allocno pseudo regs not allocated, | |
886 | or it is or has a hardware reg. First handle the pseudo-regs. */ | |
887 | if (regno >= FIRST_PSEUDO_REGISTER) | |
888 | { | |
889 | if (reg_allocno[regno] >= 0) | |
890 | { | |
891 | SET_ALLOCNO_LIVE (reg_allocno[regno]); | |
892 | record_one_conflict (regno); | |
893 | } | |
894 | } | |
895 | /* Handle hardware regs (and pseudos allocated to hard regs). */ | |
896 | else if (! fixed_regs[regno]) | |
897 | { | |
898 | register int last = regno + HARD_REGNO_NREGS (regno, GET_MODE (reg)); | |
899 | while (regno < last) | |
900 | { | |
901 | record_one_conflict (regno); | |
902 | SET_HARD_REG_BIT (hard_regs_live, regno); | |
903 | regno++; | |
904 | } | |
905 | } | |
906 | } | |
907 | \f | |
908 | /* Mark REG as being dead (following the insn being scanned now). | |
909 | Store a 0 in regs_live or allocnos_live for this register. */ | |
910 | ||
911 | static void | |
912 | mark_reg_death (reg) | |
913 | rtx reg; | |
914 | { | |
915 | register int regno = REGNO (reg); | |
916 | ||
917 | /* For pseudo reg, see if it has been assigned a hardware reg. */ | |
918 | if (reg_renumber[regno] >= 0) | |
919 | regno = reg_renumber[regno]; | |
920 | ||
921 | /* Either this is one of the max_allocno pseudo regs not allocated, | |
922 | or it is a hardware reg. First handle the pseudo-regs. */ | |
923 | if (regno >= FIRST_PSEUDO_REGISTER) | |
924 | { | |
925 | if (reg_allocno[regno] >= 0) | |
926 | CLEAR_ALLOCNO_LIVE (reg_allocno[regno]); | |
927 | } | |
928 | /* Handle hardware regs (and pseudos allocated to hard regs). */ | |
929 | else if (! fixed_regs[regno]) | |
930 | { | |
931 | /* Pseudo regs already assigned hardware regs are treated | |
932 | almost the same as explicit hardware regs. */ | |
933 | register int last = regno + HARD_REGNO_NREGS (regno, GET_MODE (reg)); | |
934 | while (regno < last) | |
935 | { | |
936 | CLEAR_HARD_REG_BIT (hard_regs_live, regno); | |
937 | regno++; | |
938 | } | |
939 | } | |
940 | } | |
941 | ||
942 | /* Mark hard reg REGNO as currently live, assuming machine mode MODE | |
943 | for the value stored in it. MODE determines how many consecutive | |
944 | registers are actually in use. Do not record conflicts; | |
945 | it is assumed that the caller will do that. */ | |
946 | ||
947 | static void | |
948 | mark_reg_live_nc (regno, mode) | |
949 | register int regno; | |
950 | enum machine_mode mode; | |
951 | { | |
952 | register int last = regno + HARD_REGNO_NREGS (regno, mode); | |
953 | while (regno < last) | |
954 | { | |
955 | SET_HARD_REG_BIT (hard_regs_live, regno); | |
956 | regno++; | |
957 | } | |
958 | } | |
959 | \f | |
960 | /* Try to set a preference for an allocno to a hard register. | |
961 | We are passed DEST and SRC which are the operands of a SET. It is known | |
962 | that SRC is a register. If SRC or the first operand of SRC is a register, | |
963 | try to set a preference. If one of the two is a hard register and the other | |
964 | is a pseudo-register, mark the preference. | |
965 | ||
966 | Note that we are not as agressive as local-alloc in trying to tie a | |
967 | pseudo-register to a hard register. */ | |
968 | ||
969 | static void | |
970 | set_preference (dest, src) | |
971 | rtx dest, src; | |
972 | { | |
973 | int src_regno, dest_regno; | |
974 | /* Amount to add to the hard regno for SRC, or subtract from that for DEST, | |
975 | to compensate for subregs in SRC or DEST. */ | |
976 | int offset = 0; | |
977 | ||
978 | if (GET_RTX_FORMAT (GET_CODE (src))[0] == 'e') | |
979 | src = XEXP (src, 0); | |
980 | ||
981 | /* Get the reg number for both SRC and DEST. | |
982 | If neither is a reg, give up. */ | |
983 | ||
984 | if (GET_CODE (src) == REG) | |
985 | src_regno = REGNO (src); | |
986 | else if (GET_CODE (src) == SUBREG && GET_CODE (SUBREG_REG (src)) == REG) | |
987 | { | |
988 | src_regno = REGNO (SUBREG_REG (src)); | |
989 | offset += SUBREG_WORD (src); | |
990 | } | |
991 | else | |
992 | return; | |
993 | ||
994 | if (GET_CODE (dest) == REG) | |
995 | dest_regno = REGNO (dest); | |
996 | else if (GET_CODE (dest) == SUBREG && GET_CODE (SUBREG_REG (dest)) == REG) | |
997 | { | |
998 | dest_regno = REGNO (SUBREG_REG (dest)); | |
999 | offset -= SUBREG_WORD (dest); | |
1000 | } | |
1001 | else | |
1002 | return; | |
1003 | ||
1004 | /* Convert either or both to hard reg numbers. */ | |
1005 | ||
1006 | if (reg_renumber[src_regno] >= 0) | |
1007 | src_regno = reg_renumber[src_regno]; | |
1008 | ||
1009 | if (reg_renumber[dest_regno] >= 0) | |
1010 | dest_regno = reg_renumber[dest_regno]; | |
1011 | ||
1012 | /* Now if one is a hard reg and the other is a global pseudo | |
1013 | then give the other a preference. */ | |
1014 | ||
1015 | if (dest_regno < FIRST_PSEUDO_REGISTER && src_regno >= FIRST_PSEUDO_REGISTER | |
1016 | && reg_allocno[src_regno] >= 0) | |
1017 | { | |
1018 | dest_regno -= offset; | |
1019 | if (dest_regno >= 0 && dest_regno < FIRST_PSEUDO_REGISTER) | |
1020 | { | |
1021 | SET_REGBIT (hard_reg_preferences, | |
1022 | reg_allocno[src_regno], dest_regno); | |
1023 | SET_HARD_REG_BIT (regs_someone_prefers, dest_regno); | |
1024 | } | |
1025 | } | |
1026 | ||
1027 | if (src_regno < FIRST_PSEUDO_REGISTER && dest_regno >= FIRST_PSEUDO_REGISTER | |
1028 | && reg_allocno[dest_regno] >= 0) | |
1029 | { | |
1030 | src_regno += offset; | |
1031 | if (src_regno >= 0 && src_regno < FIRST_PSEUDO_REGISTER) | |
1032 | { | |
1033 | SET_REGBIT (hard_reg_preferences, | |
1034 | reg_allocno[dest_regno], src_regno); | |
1035 | SET_HARD_REG_BIT (regs_someone_prefers, src_regno); | |
1036 | } | |
1037 | } | |
1038 | } | |
1039 | \f | |
1040 | /* Print debugging trace information if -greg switch is given, | |
1041 | showing the information on which the allocation decisions are based. */ | |
1042 | ||
1043 | static void | |
1044 | dump_conflicts (file) | |
1045 | FILE *file; | |
1046 | { | |
1047 | register int i; | |
1048 | fprintf (file, ";; %d regs to allocate:", max_allocno); | |
1049 | for (i = 0; i < max_allocno; i++) | |
1050 | { | |
1051 | fprintf (file, " %d", allocno_reg[allocno_order[i]]); | |
1052 | if (allocno_size[allocno_order[i]] != 1) | |
1053 | fprintf (file, " (%d)", allocno_size[allocno_order[i]]); | |
1054 | } | |
1055 | fprintf (file, "\n"); | |
1056 | ||
1057 | for (i = 0; i < max_allocno; i++) | |
1058 | { | |
1059 | register int j; | |
1060 | fprintf (file, ";; %d conflicts:", allocno_reg[i]); | |
1061 | for (j = 0; j < max_allocno; j++) | |
1062 | if (CONFLICTP (i, j) || CONFLICTP (j, i)) | |
1063 | fprintf (file, " %d", allocno_reg[j]); | |
1064 | for (j = 0; j < FIRST_PSEUDO_REGISTER; j++) | |
1065 | if (TEST_HARD_REG_BIT (hard_reg_conflicts[i], j)) | |
1066 | fprintf (file, " %d", j); | |
1067 | fprintf (file, "\n"); | |
1068 | } | |
1069 | fprintf (file, "\n"); | |
1070 | } | |
1071 | ||
1072 | void | |
1073 | dump_global_regs (file) | |
1074 | FILE *file; | |
1075 | { | |
1076 | register int i; | |
1077 | ||
1078 | fprintf (file, ";; Register dispositions:"); | |
1079 | for (i = FIRST_PSEUDO_REGISTER; i < max_regno; i++) | |
1080 | { | |
1081 | if (reg_renumber[i] >= 0) | |
1082 | fprintf (file, " %d in %d ", i, reg_renumber[i]); | |
1083 | } | |
1084 | ||
1085 | fprintf (file, "\n\n;; Hard regs used: "); | |
1086 | for (i = 0; i < FIRST_PSEUDO_REGISTER; i++) | |
1087 | if (regs_ever_live[i]) | |
1088 | fprintf (file, " %d", i); | |
1089 | fprintf (file, "\n\n"); | |
1090 | } |