1 /* Allocate registers for pseudo-registers that span basic blocks.
2 Copyright (C) 1987, 88, 91, 94, 96-98, 1999 Free Software Foundation, Inc.
4 This file is part of GNU CC.
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)
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.
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, 59 Temple Place - Suite 330,
19 Boston, MA 02111-1307, USA. */
26 #include "hard-reg-set.h"
30 #include "basic-block.h"
33 #include "insn-config.h"
38 /* This pass of the compiler performs global register allocation.
39 It assigns hard register numbers to all the pseudo registers
40 that were not handled in local_alloc. Assignments are recorded
41 in the vector reg_renumber, not by changing the rtl code.
42 (Such changes are made by final). The entry point is
43 the function global_alloc.
45 After allocation is complete, the reload pass is run as a subroutine
46 of this pass, so that when a pseudo reg loses its hard reg due to
47 spilling it is possible to make a second attempt to find a hard
48 reg for it. The reload pass is independent in other respects
49 and it is run even when stupid register allocation is in use.
51 1. Assign allocation-numbers (allocnos) to the pseudo-registers
52 still needing allocations and to the pseudo-registers currently
53 allocated by local-alloc which may be spilled by reload.
54 Set up tables reg_allocno and allocno_reg to map
55 reg numbers to allocnos and vice versa.
56 max_allocno gets the number of allocnos in use.
58 2. Allocate a max_allocno by max_allocno conflict bit matrix and clear it.
59 Allocate a max_allocno by FIRST_PSEUDO_REGISTER conflict matrix
60 for conflicts between allocnos and explicit hard register use
61 (which includes use of pseudo-registers allocated by local_alloc).
63 3. For each basic block
64 walk forward through the block, recording which
65 pseudo-registers and which hardware registers are live.
66 Build the conflict matrix between the pseudo-registers
67 and another of pseudo-registers versus hardware registers.
68 Also record the preferred hardware registers
69 for each pseudo-register.
71 4. Sort a table of the allocnos into order of
72 desirability of the variables.
74 5. Allocate the variables in that order; each if possible into
75 a preferred register, else into another register. */
77 /* Number of pseudo-registers which are candidates for allocation. */
79 static int max_allocno;
81 /* Indexed by (pseudo) reg number, gives the allocno, or -1
82 for pseudo registers which are not to be allocated. */
84 static int *reg_allocno;
86 /* Indexed by allocno, gives the reg number. */
88 static int *allocno_reg;
90 /* A vector of the integers from 0 to max_allocno-1,
91 sorted in the order of first-to-be-allocated first. */
93 static int *allocno_order;
95 /* Indexed by an allocno, gives the number of consecutive
96 hard registers needed by that pseudo reg. */
98 static int *allocno_size;
100 /* Indexed by (pseudo) reg number, gives the number of another
101 lower-numbered pseudo reg which can share a hard reg with this pseudo
102 *even if the two pseudos would otherwise appear to conflict*. */
104 static int *reg_may_share;
106 /* Define the number of bits in each element of `conflicts' and what
107 type that element has. We use the largest integer format on the
110 #define INT_BITS HOST_BITS_PER_WIDE_INT
111 #define INT_TYPE HOST_WIDE_INT
113 /* max_allocno by max_allocno array of bits,
114 recording whether two allocno's conflict (can't go in the same
117 `conflicts' is not symmetric; a conflict between allocno's i and j
118 is recorded either in element i,j or in element j,i. */
120 static INT_TYPE *conflicts;
122 /* Number of ints require to hold max_allocno bits.
123 This is the length of a row in `conflicts'. */
125 static int allocno_row_words;
127 /* Two macros to test or store 1 in an element of `conflicts'. */
129 #define CONFLICTP(I, J) \
130 (conflicts[(I) * allocno_row_words + (J) / INT_BITS] \
131 & ((INT_TYPE) 1 << ((J) % INT_BITS)))
133 #define SET_CONFLICT(I, J) \
134 (conflicts[(I) * allocno_row_words + (J) / INT_BITS] \
135 |= ((INT_TYPE) 1 << ((J) % INT_BITS)))
137 /* Set of hard regs currently live (during scan of all insns). */
139 static HARD_REG_SET hard_regs_live;
141 /* Indexed by N, set of hard regs conflicting with allocno N. */
143 static HARD_REG_SET *hard_reg_conflicts;
145 /* Indexed by N, set of hard regs preferred by allocno N.
146 This is used to make allocnos go into regs that are copied to or from them,
147 when possible, to reduce register shuffling. */
149 static HARD_REG_SET *hard_reg_preferences;
151 /* Similar, but just counts register preferences made in simple copy
152 operations, rather than arithmetic. These are given priority because
153 we can always eliminate an insn by using these, but using a register
154 in the above list won't always eliminate an insn. */
156 static HARD_REG_SET *hard_reg_copy_preferences;
158 /* Similar to hard_reg_preferences, but includes bits for subsequent
159 registers when an allocno is multi-word. The above variable is used for
160 allocation while this is used to build reg_someone_prefers, below. */
162 static HARD_REG_SET *hard_reg_full_preferences;
164 /* Indexed by N, set of hard registers that some later allocno has a
167 static HARD_REG_SET *regs_someone_prefers;
169 /* Set of registers that global-alloc isn't supposed to use. */
171 static HARD_REG_SET no_global_alloc_regs;
173 /* Set of registers used so far. */
175 static HARD_REG_SET regs_used_so_far;
177 /* Number of calls crossed by each allocno. */
179 static int *allocno_calls_crossed;
181 /* Number of refs (weighted) to each allocno. */
183 static int *allocno_n_refs;
185 /* Guess at live length of each allocno.
186 This is actually the max of the live lengths of the regs. */
188 static int *allocno_live_length;
190 /* Number of refs (weighted) to each hard reg, as used by local alloc.
191 It is zero for a reg that contains global pseudos or is explicitly used. */
193 static int local_reg_n_refs[FIRST_PSEUDO_REGISTER];
195 /* Guess at live length of each hard reg, as used by local alloc.
196 This is actually the sum of the live lengths of the specific regs. */
198 static int local_reg_live_length[FIRST_PSEUDO_REGISTER];
200 /* Test a bit in TABLE, a vector of HARD_REG_SETs,
201 for vector element I, and hard register number J. */
203 #define REGBITP(TABLE, I, J) TEST_HARD_REG_BIT (TABLE[I], J)
205 /* Set to 1 a bit in a vector of HARD_REG_SETs. Works like REGBITP. */
207 #define SET_REGBIT(TABLE, I, J) SET_HARD_REG_BIT (TABLE[I], J)
209 /* Bit mask for allocnos live at current point in the scan. */
211 static INT_TYPE *allocnos_live;
213 /* Test, set or clear bit number I in allocnos_live,
214 a bit vector indexed by allocno. */
216 #define ALLOCNO_LIVE_P(I) \
217 (allocnos_live[(I) / INT_BITS] & ((INT_TYPE) 1 << ((I) % INT_BITS)))
219 #define SET_ALLOCNO_LIVE(I) \
220 (allocnos_live[(I) / INT_BITS] |= ((INT_TYPE) 1 << ((I) % INT_BITS)))
222 #define CLEAR_ALLOCNO_LIVE(I) \
223 (allocnos_live[(I) / INT_BITS] &= ~((INT_TYPE) 1 << ((I) % INT_BITS)))
225 /* This is turned off because it doesn't work right for DImode.
226 (And it is only used for DImode, so the other cases are worthless.)
227 The problem is that it isn't true that there is NO possibility of conflict;
228 only that there is no conflict if the two pseudos get the exact same regs.
229 If they were allocated with a partial overlap, there would be a conflict.
230 We can't safely turn off the conflict unless we have another way to
231 prevent the partial overlap.
233 Idea: change hard_reg_conflicts so that instead of recording which
234 hard regs the allocno may not overlap, it records where the allocno
235 may not start. Change both where it is used and where it is updated.
236 Then there is a way to record that (reg:DI 108) may start at 10
237 but not at 9 or 11. There is still the question of how to record
238 this semi-conflict between two pseudos. */
240 /* Reg pairs for which conflict after the current insn
241 is inhibited by a REG_NO_CONFLICT note.
242 If the table gets full, we ignore any other notes--that is conservative. */
243 #define NUM_NO_CONFLICT_PAIRS 4
244 /* Number of pairs in use in this insn. */
245 int n_no_conflict_pairs;
246 static struct { int allocno1, allocno2;}
247 no_conflict_pairs[NUM_NO_CONFLICT_PAIRS];
250 /* Record all regs that are set in any one insn.
251 Communication from mark_reg_{store,clobber} and global_conflicts. */
253 static rtx *regs_set;
254 static int n_regs_set;
256 /* All registers that can be eliminated. */
258 static HARD_REG_SET eliminable_regset;
260 static int allocno_compare PROTO((const PTR, const PTR));
261 static void global_conflicts PROTO((void));
262 static void expand_preferences PROTO((void));
263 static void prune_preferences PROTO((void));
264 static void find_reg PROTO((int, HARD_REG_SET, int, int, int));
265 static void record_one_conflict PROTO((int));
266 static void record_conflicts PROTO((int *, int));
267 static void mark_reg_store PROTO((rtx, rtx));
268 static void mark_reg_clobber PROTO((rtx, rtx));
269 static void mark_reg_conflicts PROTO((rtx));
270 static void mark_reg_death PROTO((rtx));
271 static void mark_reg_live_nc PROTO((int, enum machine_mode));
272 static void set_preference PROTO((rtx, rtx));
273 static void dump_conflicts PROTO((FILE *));
274 static void reg_becomes_live PROTO((rtx, rtx));
275 static void reg_dies PROTO((int, enum machine_mode));
276 static void build_insn_chain PROTO((rtx));
278 /* Perform allocation of pseudo-registers not allocated by local_alloc.
279 FILE is a file to output debugging information on,
280 or zero if such output is not desired.
282 Return value is nonzero if reload failed
283 and we must not do any more for this function. */
290 #ifdef ELIMINABLE_REGS
291 static struct {int from, to; } eliminables[] = ELIMINABLE_REGS;
294 = (! flag_omit_frame_pointer
295 #ifdef EXIT_IGNORE_STACK
296 || (current_function_calls_alloca && EXIT_IGNORE_STACK)
298 || FRAME_POINTER_REQUIRED);
305 /* A machine may have certain hard registers that
306 are safe to use only within a basic block. */
308 CLEAR_HARD_REG_SET (no_global_alloc_regs);
309 #ifdef OVERLAPPING_REGNO_P
310 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
311 if (OVERLAPPING_REGNO_P (i))
312 SET_HARD_REG_BIT (no_global_alloc_regs, i);
315 /* Build the regset of all eliminable registers and show we can't use those
316 that we already know won't be eliminated. */
317 #ifdef ELIMINABLE_REGS
318 for (i = 0; i < sizeof eliminables / sizeof eliminables[0]; i++)
320 SET_HARD_REG_BIT (eliminable_regset, eliminables[i].from);
322 if (! CAN_ELIMINATE (eliminables[i].from, eliminables[i].to)
323 || (eliminables[i].to == STACK_POINTER_REGNUM && need_fp))
324 SET_HARD_REG_BIT (no_global_alloc_regs, eliminables[i].from);
326 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
327 SET_HARD_REG_BIT (eliminable_regset, HARD_FRAME_POINTER_REGNUM);
329 SET_HARD_REG_BIT (no_global_alloc_regs, HARD_FRAME_POINTER_REGNUM);
333 SET_HARD_REG_BIT (eliminable_regset, FRAME_POINTER_REGNUM);
335 SET_HARD_REG_BIT (no_global_alloc_regs, FRAME_POINTER_REGNUM);
338 /* Track which registers have already been used. Start with registers
339 explicitly in the rtl, then registers allocated by local register
342 CLEAR_HARD_REG_SET (regs_used_so_far);
343 #ifdef LEAF_REGISTERS
344 /* If we are doing the leaf function optimization, and this is a leaf
345 function, it means that the registers that take work to save are those
346 that need a register window. So prefer the ones that can be used in
350 static char leaf_regs[] = LEAF_REGISTERS;
352 if (only_leaf_regs_used () && leaf_function_p ())
353 cheap_regs = leaf_regs;
355 cheap_regs = call_used_regs;
356 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
357 if (regs_ever_live[i] || cheap_regs[i])
358 SET_HARD_REG_BIT (regs_used_so_far, i);
361 /* We consider registers that do not have to be saved over calls as if
362 they were already used since there is no cost in using them. */
363 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
364 if (regs_ever_live[i] || call_used_regs[i])
365 SET_HARD_REG_BIT (regs_used_so_far, i);
368 for (i = FIRST_PSEUDO_REGISTER; i < (size_t) max_regno; i++)
369 if (reg_renumber[i] >= 0)
370 SET_HARD_REG_BIT (regs_used_so_far, reg_renumber[i]);
372 /* Establish mappings from register number to allocation number
373 and vice versa. In the process, count the allocnos. */
375 reg_allocno = (int *) alloca (max_regno * sizeof (int));
377 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
380 /* Initialize the shared-hard-reg mapping
381 from the list of pairs that may share. */
382 reg_may_share = (int *) alloca (max_regno * sizeof (int));
383 bzero ((char *) reg_may_share, max_regno * sizeof (int));
384 for (x = regs_may_share; x; x = XEXP (XEXP (x, 1), 1))
386 int r1 = REGNO (XEXP (x, 0));
387 int r2 = REGNO (XEXP (XEXP (x, 1), 0));
389 reg_may_share[r1] = r2;
391 reg_may_share[r2] = r1;
394 for (i = FIRST_PSEUDO_REGISTER; i < (size_t) max_regno; i++)
395 /* Note that reg_live_length[i] < 0 indicates a "constant" reg
396 that we are supposed to refrain from putting in a hard reg.
397 -2 means do make an allocno but don't allocate it. */
398 if (REG_N_REFS (i) != 0 && REG_LIVE_LENGTH (i) != -1
399 /* Don't allocate pseudos that cross calls,
400 if this function receives a nonlocal goto. */
401 && (! current_function_has_nonlocal_label
402 || REG_N_CALLS_CROSSED (i) == 0))
404 if (reg_renumber[i] < 0 && reg_may_share[i] && reg_allocno[reg_may_share[i]] >= 0)
405 reg_allocno[i] = reg_allocno[reg_may_share[i]];
407 reg_allocno[i] = max_allocno++;
408 if (REG_LIVE_LENGTH (i) == 0)
414 allocno_reg = (int *) alloca (max_allocno * sizeof (int));
415 allocno_size = (int *) alloca (max_allocno * sizeof (int));
416 allocno_calls_crossed = (int *) alloca (max_allocno * sizeof (int));
417 allocno_n_refs = (int *) alloca (max_allocno * sizeof (int));
418 allocno_live_length = (int *) alloca (max_allocno * sizeof (int));
419 bzero ((char *) allocno_size, max_allocno * sizeof (int));
420 bzero ((char *) allocno_calls_crossed, max_allocno * sizeof (int));
421 bzero ((char *) allocno_n_refs, max_allocno * sizeof (int));
422 bzero ((char *) allocno_live_length, max_allocno * sizeof (int));
424 for (i = FIRST_PSEUDO_REGISTER; i < (size_t) max_regno; i++)
425 if (reg_allocno[i] >= 0)
427 int allocno = reg_allocno[i];
428 allocno_reg[allocno] = i;
429 allocno_size[allocno] = PSEUDO_REGNO_SIZE (i);
430 allocno_calls_crossed[allocno] += REG_N_CALLS_CROSSED (i);
431 allocno_n_refs[allocno] += REG_N_REFS (i);
432 if (allocno_live_length[allocno] < REG_LIVE_LENGTH (i))
433 allocno_live_length[allocno] = REG_LIVE_LENGTH (i);
436 /* Calculate amount of usage of each hard reg by pseudos
437 allocated by local-alloc. This is to see if we want to
439 bzero ((char *) local_reg_live_length, sizeof local_reg_live_length);
440 bzero ((char *) local_reg_n_refs, sizeof local_reg_n_refs);
441 for (i = FIRST_PSEUDO_REGISTER; i < (size_t) max_regno; i++)
442 if (reg_renumber[i] >= 0)
444 int regno = reg_renumber[i];
445 int endregno = regno + HARD_REGNO_NREGS (regno, PSEUDO_REGNO_MODE (i));
448 for (j = regno; j < endregno; j++)
450 local_reg_n_refs[j] += REG_N_REFS (i);
451 local_reg_live_length[j] += REG_LIVE_LENGTH (i);
455 /* We can't override local-alloc for a reg used not just by local-alloc. */
456 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
457 if (regs_ever_live[i])
458 local_reg_n_refs[i] = 0;
460 /* Allocate the space for the conflict and preference tables and
464 = (HARD_REG_SET *) alloca (max_allocno * sizeof (HARD_REG_SET));
465 bzero ((char *) hard_reg_conflicts, max_allocno * sizeof (HARD_REG_SET));
468 = (HARD_REG_SET *) alloca (max_allocno * sizeof (HARD_REG_SET));
469 bzero ((char *) hard_reg_preferences, max_allocno * sizeof (HARD_REG_SET));
471 hard_reg_copy_preferences
472 = (HARD_REG_SET *) alloca (max_allocno * sizeof (HARD_REG_SET));
473 bzero ((char *) hard_reg_copy_preferences,
474 max_allocno * sizeof (HARD_REG_SET));
476 hard_reg_full_preferences
477 = (HARD_REG_SET *) alloca (max_allocno * sizeof (HARD_REG_SET));
478 bzero ((char *) hard_reg_full_preferences,
479 max_allocno * sizeof (HARD_REG_SET));
482 = (HARD_REG_SET *) alloca (max_allocno * sizeof (HARD_REG_SET));
483 bzero ((char *) regs_someone_prefers, max_allocno * sizeof (HARD_REG_SET));
485 allocno_row_words = (max_allocno + INT_BITS - 1) / INT_BITS;
487 /* We used to use alloca here, but the size of what it would try to
488 allocate would occasionally cause it to exceed the stack limit and
489 cause unpredictable core dumps. Some examples were > 2Mb in size. */
490 conflicts = (INT_TYPE *) xcalloc (max_allocno * allocno_row_words,
493 allocnos_live = (INT_TYPE *) alloca (allocno_row_words * sizeof (INT_TYPE));
495 /* If there is work to be done (at least one reg to allocate),
496 perform global conflict analysis and allocate the regs. */
500 /* Scan all the insns and compute the conflicts among allocnos
501 and between allocnos and hard regs. */
505 /* Eliminate conflicts between pseudos and eliminable registers. If
506 the register is not eliminated, the pseudo won't really be able to
507 live in the eliminable register, so the conflict doesn't matter.
508 If we do eliminate the register, the conflict will no longer exist.
509 So in either case, we can ignore the conflict. Likewise for
512 for (i = 0; i < (size_t) max_allocno; i++)
514 AND_COMPL_HARD_REG_SET (hard_reg_conflicts[i], eliminable_regset);
515 AND_COMPL_HARD_REG_SET (hard_reg_copy_preferences[i],
517 AND_COMPL_HARD_REG_SET (hard_reg_preferences[i], eliminable_regset);
520 /* Try to expand the preferences by merging them between allocnos. */
522 expand_preferences ();
524 /* Determine the order to allocate the remaining pseudo registers. */
526 allocno_order = (int *) alloca (max_allocno * sizeof (int));
527 for (i = 0; i < (size_t) max_allocno; i++)
528 allocno_order[i] = i;
530 /* Default the size to 1, since allocno_compare uses it to divide by.
531 Also convert allocno_live_length of zero to -1. A length of zero
532 can occur when all the registers for that allocno have reg_live_length
533 equal to -2. In this case, we want to make an allocno, but not
534 allocate it. So avoid the divide-by-zero and set it to a low
537 for (i = 0; i < (size_t) max_allocno; i++)
539 if (allocno_size[i] == 0)
541 if (allocno_live_length[i] == 0)
542 allocno_live_length[i] = -1;
545 qsort (allocno_order, max_allocno, sizeof (int), allocno_compare);
547 prune_preferences ();
550 dump_conflicts (file);
552 /* Try allocating them, one by one, in that order,
553 except for parameters marked with reg_live_length[regno] == -2. */
555 for (i = 0; i < (size_t) max_allocno; i++)
556 if (reg_renumber[allocno_reg[allocno_order[i]]] < 0
557 && REG_LIVE_LENGTH (allocno_reg[allocno_order[i]]) >= 0)
559 /* If we have more than one register class,
560 first try allocating in the class that is cheapest
561 for this pseudo-reg. If that fails, try any reg. */
562 if (N_REG_CLASSES > 1)
564 find_reg (allocno_order[i], 0, 0, 0, 0);
565 if (reg_renumber[allocno_reg[allocno_order[i]]] >= 0)
568 if (reg_alternate_class (allocno_reg[allocno_order[i]]) != NO_REGS)
569 find_reg (allocno_order[i], 0, 1, 0, 0);
573 /* Do the reloads now while the allocno data still exist, so that we can
574 try to assign new hard regs to any pseudo regs that are spilled. */
576 #if 0 /* We need to eliminate regs even if there is no rtl code,
577 for the sake of debugging information. */
578 if (n_basic_blocks > 0)
581 build_insn_chain (get_insns ());
582 retval = reload (get_insns (), 1, file);
589 /* Sort predicate for ordering the allocnos.
590 Returns -1 (1) if *v1 should be allocated before (after) *v2. */
593 allocno_compare (v1p, v2p)
597 int v1 = *(const int *)v1p, v2 = *(const int *)v2p;
598 /* Note that the quotient will never be bigger than
599 the value of floor_log2 times the maximum number of
600 times a register can occur in one insn (surely less than 100).
601 Multiplying this by 10000 can't overflow. */
603 = (((double) (floor_log2 (allocno_n_refs[v1]) * allocno_n_refs[v1])
604 / allocno_live_length[v1])
605 * 10000 * allocno_size[v1]);
607 = (((double) (floor_log2 (allocno_n_refs[v2]) * allocno_n_refs[v2])
608 / allocno_live_length[v2])
609 * 10000 * allocno_size[v2]);
613 /* If regs are equally good, sort by allocno,
614 so that the results of qsort leave nothing to chance. */
618 /* Scan the rtl code and record all conflicts and register preferences in the
619 conflict matrices and preference tables. */
626 int *block_start_allocnos;
628 /* Make a vector that mark_reg_{store,clobber} will store in. */
629 regs_set = (rtx *) alloca (max_parallel * sizeof (rtx) * 2);
631 block_start_allocnos = (int *) alloca (max_allocno * sizeof (int));
633 for (b = 0; b < n_basic_blocks; b++)
635 bzero ((char *) allocnos_live, allocno_row_words * sizeof (INT_TYPE));
637 /* Initialize table of registers currently live
638 to the state at the beginning of this basic block.
639 This also marks the conflicts among them.
641 For pseudo-regs, there is only one bit for each one
642 no matter how many hard regs it occupies.
643 This is ok; we know the size from PSEUDO_REGNO_SIZE.
644 For explicit hard regs, we cannot know the size that way
645 since one hard reg can be used with various sizes.
646 Therefore, we must require that all the hard regs
647 implicitly live as part of a multi-word hard reg
648 are explicitly marked in basic_block_live_at_start. */
651 register regset old = BASIC_BLOCK (b)->global_live_at_start;
654 REG_SET_TO_HARD_REG_SET (hard_regs_live, old);
655 EXECUTE_IF_SET_IN_REG_SET (old, FIRST_PSEUDO_REGISTER, i,
657 register int a = reg_allocno[i];
660 SET_ALLOCNO_LIVE (a);
661 block_start_allocnos[ax++] = a;
663 else if ((a = reg_renumber[i]) >= 0)
665 (a, PSEUDO_REGNO_MODE (i));
668 /* Record that each allocno now live conflicts with each other
669 allocno now live, and with each hard reg now live. */
671 record_conflicts (block_start_allocnos, ax);
675 /* Pseudos can't go in stack regs at the start of a basic block
676 that is reached by an abnormal edge. */
679 for (e = BASIC_BLOCK (b)->pred; e ; e = e->pred_next)
680 if (e->flags & EDGE_ABNORMAL)
683 for (ax = FIRST_STACK_REG; ax <= LAST_STACK_REG; ax++)
684 record_one_conflict (ax);
689 insn = BLOCK_HEAD (b);
691 /* Scan the code of this basic block, noting which allocnos
692 and hard regs are born or die. When one is born,
693 record a conflict with all others currently live. */
697 register RTX_CODE code = GET_CODE (insn);
700 /* Make regs_set an empty set. */
704 if (code == INSN || code == CALL_INSN || code == JUMP_INSN)
709 for (link = REG_NOTES (insn);
710 link && i < NUM_NO_CONFLICT_PAIRS;
711 link = XEXP (link, 1))
712 if (REG_NOTE_KIND (link) == REG_NO_CONFLICT)
714 no_conflict_pairs[i].allocno1
715 = reg_allocno[REGNO (SET_DEST (PATTERN (insn)))];
716 no_conflict_pairs[i].allocno2
717 = reg_allocno[REGNO (XEXP (link, 0))];
722 /* Mark any registers clobbered by INSN as live,
723 so they conflict with the inputs. */
725 note_stores (PATTERN (insn), mark_reg_clobber);
727 /* Mark any registers dead after INSN as dead now. */
729 for (link = REG_NOTES (insn); link; link = XEXP (link, 1))
730 if (REG_NOTE_KIND (link) == REG_DEAD)
731 mark_reg_death (XEXP (link, 0));
733 /* Mark any registers set in INSN as live,
734 and mark them as conflicting with all other live regs.
735 Clobbers are processed again, so they conflict with
736 the registers that are set. */
738 note_stores (PATTERN (insn), mark_reg_store);
741 for (link = REG_NOTES (insn); link; link = XEXP (link, 1))
742 if (REG_NOTE_KIND (link) == REG_INC)
743 mark_reg_store (XEXP (link, 0), NULL_RTX);
746 /* If INSN has multiple outputs, then any reg that dies here
747 and is used inside of an output
748 must conflict with the other outputs.
750 It is unsafe to use !single_set here since it will ignore an
751 unused output. Just because an output is unused does not mean
752 the compiler can assume the side effect will not occur.
753 Consider if REG appears in the address of an output and we
754 reload the output. If we allocate REG to the same hard
755 register as an unused output we could set the hard register
756 before the output reload insn. */
757 if (GET_CODE (PATTERN (insn)) == PARALLEL && multiple_sets (insn))
758 for (link = REG_NOTES (insn); link; link = XEXP (link, 1))
759 if (REG_NOTE_KIND (link) == REG_DEAD)
761 int used_in_output = 0;
763 rtx reg = XEXP (link, 0);
765 for (i = XVECLEN (PATTERN (insn), 0) - 1; i >= 0; i--)
767 rtx set = XVECEXP (PATTERN (insn), 0, i);
768 if (GET_CODE (set) == SET
769 && GET_CODE (SET_DEST (set)) != REG
770 && !rtx_equal_p (reg, SET_DEST (set))
771 && reg_overlap_mentioned_p (reg, SET_DEST (set)))
775 mark_reg_conflicts (reg);
778 /* Mark any registers set in INSN and then never used. */
780 while (n_regs_set > 0)
781 if (find_regno_note (insn, REG_UNUSED,
782 REGNO (regs_set[--n_regs_set])))
783 mark_reg_death (regs_set[n_regs_set]);
786 if (insn == BLOCK_END (b))
788 insn = NEXT_INSN (insn);
792 /* Expand the preference information by looking for cases where one allocno
793 dies in an insn that sets an allocno. If those two allocnos don't conflict,
794 merge any preferences between those allocnos. */
797 expand_preferences ()
803 /* We only try to handle the most common cases here. Most of the cases
804 where this wins are reg-reg copies. */
806 for (insn = get_insns (); insn; insn = NEXT_INSN (insn))
807 if (GET_RTX_CLASS (GET_CODE (insn)) == 'i'
808 && (set = single_set (insn)) != 0
809 && GET_CODE (SET_DEST (set)) == REG
810 && reg_allocno[REGNO (SET_DEST (set))] >= 0)
811 for (link = REG_NOTES (insn); link; link = XEXP (link, 1))
812 if (REG_NOTE_KIND (link) == REG_DEAD
813 && GET_CODE (XEXP (link, 0)) == REG
814 && reg_allocno[REGNO (XEXP (link, 0))] >= 0
815 && ! CONFLICTP (reg_allocno[REGNO (SET_DEST (set))],
816 reg_allocno[REGNO (XEXP (link, 0))])
817 && ! CONFLICTP (reg_allocno[REGNO (XEXP (link, 0))],
818 reg_allocno[REGNO (SET_DEST (set))]))
820 int a1 = reg_allocno[REGNO (SET_DEST (set))];
821 int a2 = reg_allocno[REGNO (XEXP (link, 0))];
823 if (XEXP (link, 0) == SET_SRC (set))
825 IOR_HARD_REG_SET (hard_reg_copy_preferences[a1],
826 hard_reg_copy_preferences[a2]);
827 IOR_HARD_REG_SET (hard_reg_copy_preferences[a2],
828 hard_reg_copy_preferences[a1]);
831 IOR_HARD_REG_SET (hard_reg_preferences[a1],
832 hard_reg_preferences[a2]);
833 IOR_HARD_REG_SET (hard_reg_preferences[a2],
834 hard_reg_preferences[a1]);
835 IOR_HARD_REG_SET (hard_reg_full_preferences[a1],
836 hard_reg_full_preferences[a2]);
837 IOR_HARD_REG_SET (hard_reg_full_preferences[a2],
838 hard_reg_full_preferences[a1]);
842 /* Prune the preferences for global registers to exclude registers that cannot
845 Compute `regs_someone_prefers', which is a bitmask of the hard registers
846 that are preferred by conflicting registers of lower priority. If possible,
847 we will avoid using these registers. */
855 /* Scan least most important to most important.
856 For each allocno, remove from preferences registers that cannot be used,
857 either because of conflicts or register type. Then compute all registers
858 preferred by each lower-priority register that conflicts. */
860 for (i = max_allocno - 1; i >= 0; i--)
862 HARD_REG_SET temp, temp2;
864 allocno = allocno_order[i];
865 COPY_HARD_REG_SET (temp, hard_reg_conflicts[allocno]);
867 if (allocno_calls_crossed[allocno] == 0)
868 IOR_HARD_REG_SET (temp, fixed_reg_set);
870 IOR_HARD_REG_SET (temp, call_used_reg_set);
872 IOR_COMPL_HARD_REG_SET
874 reg_class_contents[(int) reg_preferred_class (allocno_reg[allocno])]);
876 AND_COMPL_HARD_REG_SET (hard_reg_preferences[allocno], temp);
877 AND_COMPL_HARD_REG_SET (hard_reg_copy_preferences[allocno], temp);
878 AND_COMPL_HARD_REG_SET (hard_reg_full_preferences[allocno], temp);
880 /* Merge in the preferences of lower-priority registers (they have
881 already been pruned). If we also prefer some of those registers,
882 don't exclude them unless we are of a smaller size (in which case
883 we want to give the lower-priority allocno the first chance for
885 CLEAR_HARD_REG_SET (temp);
886 CLEAR_HARD_REG_SET (temp2);
887 for (j = i + 1; j < max_allocno; j++)
888 if (CONFLICTP (allocno, allocno_order[j])
889 || CONFLICTP (allocno_order[j], allocno))
891 if (allocno_size[allocno_order[j]] <= allocno_size[allocno])
892 IOR_HARD_REG_SET (temp,
893 hard_reg_full_preferences[allocno_order[j]]);
895 IOR_HARD_REG_SET (temp2,
896 hard_reg_full_preferences[allocno_order[j]]);
898 AND_COMPL_HARD_REG_SET (temp, hard_reg_full_preferences[allocno]);
899 IOR_HARD_REG_SET (temp, temp2);
900 COPY_HARD_REG_SET (regs_someone_prefers[allocno], temp);
904 /* Assign a hard register to ALLOCNO; look for one that is the beginning
905 of a long enough stretch of hard regs none of which conflicts with ALLOCNO.
906 The registers marked in PREFREGS are tried first.
908 LOSERS, if non-zero, is a HARD_REG_SET indicating registers that cannot
909 be used for this allocation.
911 If ALT_REGS_P is zero, consider only the preferred class of ALLOCNO's reg.
912 Otherwise ignore that preferred class and use the alternate class.
914 If ACCEPT_CALL_CLOBBERED is nonzero, accept a call-clobbered hard reg that
915 will have to be saved and restored at calls.
917 RETRYING is nonzero if this is called from retry_global_alloc.
919 If we find one, record it in reg_renumber.
920 If not, do nothing. */
923 find_reg (allocno, losers, alt_regs_p, accept_call_clobbered, retrying)
927 int accept_call_clobbered;
930 register int i, best_reg, pass;
932 register /* Declare it register if it's a scalar. */
934 HARD_REG_SET used, used1, used2;
936 enum reg_class class = (alt_regs_p
937 ? reg_alternate_class (allocno_reg[allocno])
938 : reg_preferred_class (allocno_reg[allocno]));
939 enum machine_mode mode = PSEUDO_REGNO_MODE (allocno_reg[allocno]);
941 if (accept_call_clobbered)
942 COPY_HARD_REG_SET (used1, call_fixed_reg_set);
943 else if (allocno_calls_crossed[allocno] == 0)
944 COPY_HARD_REG_SET (used1, fixed_reg_set);
946 COPY_HARD_REG_SET (used1, call_used_reg_set);
948 /* Some registers should not be allocated in global-alloc. */
949 IOR_HARD_REG_SET (used1, no_global_alloc_regs);
951 IOR_HARD_REG_SET (used1, losers);
953 IOR_COMPL_HARD_REG_SET (used1, reg_class_contents[(int) class]);
954 COPY_HARD_REG_SET (used2, used1);
956 IOR_HARD_REG_SET (used1, hard_reg_conflicts[allocno]);
958 #ifdef CLASS_CANNOT_CHANGE_SIZE
959 if (REG_CHANGES_SIZE (allocno_reg[allocno]))
960 IOR_HARD_REG_SET (used1,
961 reg_class_contents[(int) CLASS_CANNOT_CHANGE_SIZE]);
964 /* Try each hard reg to see if it fits. Do this in two passes.
965 In the first pass, skip registers that are preferred by some other pseudo
966 to give it a better chance of getting one of those registers. Only if
967 we can't get a register when excluding those do we take one of them.
968 However, we never allocate a register for the first time in pass 0. */
970 COPY_HARD_REG_SET (used, used1);
971 IOR_COMPL_HARD_REG_SET (used, regs_used_so_far);
972 IOR_HARD_REG_SET (used, regs_someone_prefers[allocno]);
975 for (i = FIRST_PSEUDO_REGISTER, pass = 0;
976 pass <= 1 && i >= FIRST_PSEUDO_REGISTER;
980 COPY_HARD_REG_SET (used, used1);
981 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
983 #ifdef REG_ALLOC_ORDER
984 int regno = reg_alloc_order[i];
988 if (! TEST_HARD_REG_BIT (used, regno)
989 && HARD_REGNO_MODE_OK (regno, mode)
990 && (allocno_calls_crossed[allocno] == 0
991 || accept_call_clobbered
992 || ! HARD_REGNO_CALL_PART_CLOBBERED (regno, mode)))
995 register int lim = regno + HARD_REGNO_NREGS (regno, mode);
998 && ! TEST_HARD_REG_BIT (used, j));
1005 #ifndef REG_ALLOC_ORDER
1006 i = j; /* Skip starting points we know will lose */
1012 /* See if there is a preferred register with the same class as the register
1013 we allocated above. Making this restriction prevents register
1014 preferencing from creating worse register allocation.
1016 Remove from the preferred registers and conflicting registers. Note that
1017 additional conflicts may have been added after `prune_preferences' was
1020 First do this for those register with copy preferences, then all
1021 preferred registers. */
1023 AND_COMPL_HARD_REG_SET (hard_reg_copy_preferences[allocno], used);
1024 GO_IF_HARD_REG_SUBSET (hard_reg_copy_preferences[allocno],
1025 reg_class_contents[(int) NO_REGS], no_copy_prefs);
1029 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
1030 if (TEST_HARD_REG_BIT (hard_reg_copy_preferences[allocno], i)
1031 && HARD_REGNO_MODE_OK (i, mode)
1032 && (REGNO_REG_CLASS (i) == REGNO_REG_CLASS (best_reg)
1033 || reg_class_subset_p (REGNO_REG_CLASS (i),
1034 REGNO_REG_CLASS (best_reg))
1035 || reg_class_subset_p (REGNO_REG_CLASS (best_reg),
1036 REGNO_REG_CLASS (i))))
1039 register int lim = i + HARD_REGNO_NREGS (i, mode);
1042 && ! TEST_HARD_REG_BIT (used, j)
1043 && (REGNO_REG_CLASS (j)
1044 == REGNO_REG_CLASS (best_reg + (j - i))
1045 || reg_class_subset_p (REGNO_REG_CLASS (j),
1046 REGNO_REG_CLASS (best_reg + (j - i)))
1047 || reg_class_subset_p (REGNO_REG_CLASS (best_reg + (j - i)),
1048 REGNO_REG_CLASS (j))));
1059 AND_COMPL_HARD_REG_SET (hard_reg_preferences[allocno], used);
1060 GO_IF_HARD_REG_SUBSET (hard_reg_preferences[allocno],
1061 reg_class_contents[(int) NO_REGS], no_prefs);
1065 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
1066 if (TEST_HARD_REG_BIT (hard_reg_preferences[allocno], i)
1067 && HARD_REGNO_MODE_OK (i, mode)
1068 && (REGNO_REG_CLASS (i) == REGNO_REG_CLASS (best_reg)
1069 || reg_class_subset_p (REGNO_REG_CLASS (i),
1070 REGNO_REG_CLASS (best_reg))
1071 || reg_class_subset_p (REGNO_REG_CLASS (best_reg),
1072 REGNO_REG_CLASS (i))))
1075 register int lim = i + HARD_REGNO_NREGS (i, mode);
1078 && ! TEST_HARD_REG_BIT (used, j)
1079 && (REGNO_REG_CLASS (j)
1080 == REGNO_REG_CLASS (best_reg + (j - i))
1081 || reg_class_subset_p (REGNO_REG_CLASS (j),
1082 REGNO_REG_CLASS (best_reg + (j - i)))
1083 || reg_class_subset_p (REGNO_REG_CLASS (best_reg + (j - i)),
1084 REGNO_REG_CLASS (j))));
1095 /* If we haven't succeeded yet, try with caller-saves.
1096 We need not check to see if the current function has nonlocal
1097 labels because we don't put any pseudos that are live over calls in
1098 registers in that case. */
1100 if (flag_caller_saves && best_reg < 0)
1102 /* Did not find a register. If it would be profitable to
1103 allocate a call-clobbered register and save and restore it
1104 around calls, do that. */
1105 if (! accept_call_clobbered
1106 && allocno_calls_crossed[allocno] != 0
1107 && CALLER_SAVE_PROFITABLE (allocno_n_refs[allocno],
1108 allocno_calls_crossed[allocno]))
1110 HARD_REG_SET new_losers;
1112 CLEAR_HARD_REG_SET (new_losers);
1114 COPY_HARD_REG_SET (new_losers, losers);
1116 IOR_HARD_REG_SET(new_losers, losing_caller_save_reg_set);
1117 find_reg (allocno, new_losers, alt_regs_p, 1, retrying);
1118 if (reg_renumber[allocno_reg[allocno]] >= 0)
1120 caller_save_needed = 1;
1126 /* If we haven't succeeded yet,
1127 see if some hard reg that conflicts with us
1128 was utilized poorly by local-alloc.
1129 If so, kick out the regs that were put there by local-alloc
1130 so we can use it instead. */
1131 if (best_reg < 0 && !retrying
1132 /* Let's not bother with multi-reg allocnos. */
1133 && allocno_size[allocno] == 1)
1135 /* Count from the end, to find the least-used ones first. */
1136 for (i = FIRST_PSEUDO_REGISTER - 1; i >= 0; i--)
1138 #ifdef REG_ALLOC_ORDER
1139 int regno = reg_alloc_order[i];
1144 if (local_reg_n_refs[regno] != 0
1145 /* Don't use a reg no good for this pseudo. */
1146 && ! TEST_HARD_REG_BIT (used2, regno)
1147 && HARD_REGNO_MODE_OK (regno, mode)
1148 #ifdef CLASS_CANNOT_CHANGE_SIZE
1149 && ! (REG_CHANGES_SIZE (allocno_reg[allocno])
1150 && (TEST_HARD_REG_BIT
1151 (reg_class_contents[(int) CLASS_CANNOT_CHANGE_SIZE],
1156 /* We explicitly evaluate the divide results into temporary
1157 variables so as to avoid excess precision problems that occur
1158 on a i386-unknown-sysv4.2 (unixware) host. */
1160 double tmp1 = ((double) local_reg_n_refs[regno]
1161 / local_reg_live_length[regno]);
1162 double tmp2 = ((double) allocno_n_refs[allocno]
1163 / allocno_live_length[allocno]);
1167 /* Hard reg REGNO was used less in total by local regs
1168 than it would be used by this one allocno! */
1170 for (k = 0; k < max_regno; k++)
1171 if (reg_renumber[k] >= 0)
1173 int r = reg_renumber[k];
1175 = r + HARD_REGNO_NREGS (r, PSEUDO_REGNO_MODE (k));
1177 if (regno >= r && regno < endregno)
1178 reg_renumber[k] = -1;
1188 /* Did we find a register? */
1192 register int lim, j;
1193 HARD_REG_SET this_reg;
1195 /* Yes. Record it as the hard register of this pseudo-reg. */
1196 reg_renumber[allocno_reg[allocno]] = best_reg;
1197 /* Also of any pseudo-regs that share with it. */
1198 if (reg_may_share[allocno_reg[allocno]])
1199 for (j = FIRST_PSEUDO_REGISTER; j < max_regno; j++)
1200 if (reg_allocno[j] == allocno)
1201 reg_renumber[j] = best_reg;
1203 /* Make a set of the hard regs being allocated. */
1204 CLEAR_HARD_REG_SET (this_reg);
1205 lim = best_reg + HARD_REGNO_NREGS (best_reg, mode);
1206 for (j = best_reg; j < lim; j++)
1208 SET_HARD_REG_BIT (this_reg, j);
1209 SET_HARD_REG_BIT (regs_used_so_far, j);
1210 /* This is no longer a reg used just by local regs. */
1211 local_reg_n_refs[j] = 0;
1213 /* For each other pseudo-reg conflicting with this one,
1214 mark it as conflicting with the hard regs this one occupies. */
1216 for (j = 0; j < max_allocno; j++)
1217 if (CONFLICTP (lim, j) || CONFLICTP (j, lim))
1219 IOR_HARD_REG_SET (hard_reg_conflicts[j], this_reg);
1224 /* Called from `reload' to look for a hard reg to put pseudo reg REGNO in.
1225 Perhaps it had previously seemed not worth a hard reg,
1226 or perhaps its old hard reg has been commandeered for reloads.
1227 FORBIDDEN_REGS indicates certain hard regs that may not be used, even if
1228 they do not appear to be allocated.
1229 If FORBIDDEN_REGS is zero, no regs are forbidden. */
1232 retry_global_alloc (regno, forbidden_regs)
1234 HARD_REG_SET forbidden_regs;
1236 int allocno = reg_allocno[regno];
1239 /* If we have more than one register class,
1240 first try allocating in the class that is cheapest
1241 for this pseudo-reg. If that fails, try any reg. */
1242 if (N_REG_CLASSES > 1)
1243 find_reg (allocno, forbidden_regs, 0, 0, 1);
1244 if (reg_renumber[regno] < 0
1245 && reg_alternate_class (regno) != NO_REGS)
1246 find_reg (allocno, forbidden_regs, 1, 0, 1);
1248 /* If we found a register, modify the RTL for the register to
1249 show the hard register, and mark that register live. */
1250 if (reg_renumber[regno] >= 0)
1252 REGNO (regno_reg_rtx[regno]) = reg_renumber[regno];
1253 mark_home_live (regno);
1258 /* Record a conflict between register REGNO
1259 and everything currently live.
1260 REGNO must not be a pseudo reg that was allocated
1261 by local_alloc; such numbers must be translated through
1262 reg_renumber before calling here. */
1265 record_one_conflict (regno)
1270 if (regno < FIRST_PSEUDO_REGISTER)
1271 /* When a hard register becomes live,
1272 record conflicts with live pseudo regs. */
1273 for (j = 0; j < max_allocno; j++)
1275 if (ALLOCNO_LIVE_P (j))
1276 SET_HARD_REG_BIT (hard_reg_conflicts[j], regno);
1279 /* When a pseudo-register becomes live,
1280 record conflicts first with hard regs,
1281 then with other pseudo regs. */
1283 register int ialloc = reg_allocno[regno];
1284 register int ialloc_prod = ialloc * allocno_row_words;
1285 IOR_HARD_REG_SET (hard_reg_conflicts[ialloc], hard_regs_live);
1286 for (j = allocno_row_words - 1; j >= 0; j--)
1290 for (k = 0; k < n_no_conflict_pairs; k++)
1291 if (! ((j == no_conflict_pairs[k].allocno1
1292 && ialloc == no_conflict_pairs[k].allocno2)
1294 (j == no_conflict_pairs[k].allocno2
1295 && ialloc == no_conflict_pairs[k].allocno1)))
1297 conflicts[ialloc_prod + j] |= allocnos_live[j];
1302 /* Record all allocnos currently live as conflicting
1303 with each other and with all hard regs currently live.
1304 ALLOCNO_VEC is a vector of LEN allocnos, all allocnos that
1305 are currently live. Their bits are also flagged in allocnos_live. */
1308 record_conflicts (allocno_vec, len)
1309 register int *allocno_vec;
1312 register int allocno;
1314 register int ialloc_prod;
1318 allocno = allocno_vec[len];
1319 ialloc_prod = allocno * allocno_row_words;
1320 IOR_HARD_REG_SET (hard_reg_conflicts[allocno], hard_regs_live);
1321 for (j = allocno_row_words - 1; j >= 0; j--)
1322 conflicts[ialloc_prod + j] |= allocnos_live[j];
1326 /* Handle the case where REG is set by the insn being scanned,
1327 during the forward scan to accumulate conflicts.
1328 Store a 1 in regs_live or allocnos_live for this register, record how many
1329 consecutive hardware registers it actually needs,
1330 and record a conflict with all other registers already live.
1332 Note that even if REG does not remain alive after this insn,
1333 we must mark it here as live, to ensure a conflict between
1334 REG and any other regs set in this insn that really do live.
1335 This is because those other regs could be considered after this.
1337 REG might actually be something other than a register;
1338 if so, we do nothing.
1340 SETTER is 0 if this register was modified by an auto-increment (i.e.,
1341 a REG_INC note was found for it). */
1344 mark_reg_store (reg, setter)
1349 /* WORD is which word of a multi-register group is being stored.
1350 For the case where the store is actually into a SUBREG of REG.
1351 Except we don't use it; I believe the entire REG needs to be
1355 if (GET_CODE (reg) == SUBREG)
1357 word = SUBREG_WORD (reg);
1358 reg = SUBREG_REG (reg);
1361 if (GET_CODE (reg) != REG)
1364 regs_set[n_regs_set++] = reg;
1366 if (setter && GET_CODE (setter) != CLOBBER)
1367 set_preference (reg, SET_SRC (setter));
1369 regno = REGNO (reg);
1371 /* Either this is one of the max_allocno pseudo regs not allocated,
1372 or it is or has a hardware reg. First handle the pseudo-regs. */
1373 if (regno >= FIRST_PSEUDO_REGISTER)
1375 if (reg_allocno[regno] >= 0)
1377 SET_ALLOCNO_LIVE (reg_allocno[regno]);
1378 record_one_conflict (regno);
1382 if (reg_renumber[regno] >= 0)
1383 regno = reg_renumber[regno] /* + word */;
1385 /* Handle hardware regs (and pseudos allocated to hard regs). */
1386 if (regno < FIRST_PSEUDO_REGISTER && ! fixed_regs[regno])
1388 register int last = regno + HARD_REGNO_NREGS (regno, GET_MODE (reg));
1389 while (regno < last)
1391 record_one_conflict (regno);
1392 SET_HARD_REG_BIT (hard_regs_live, regno);
1398 /* Like mark_reg_set except notice just CLOBBERs; ignore SETs. */
1401 mark_reg_clobber (reg, setter)
1404 if (GET_CODE (setter) == CLOBBER)
1405 mark_reg_store (reg, setter);
1408 /* Record that REG has conflicts with all the regs currently live.
1409 Do not mark REG itself as live. */
1412 mark_reg_conflicts (reg)
1417 if (GET_CODE (reg) == SUBREG)
1418 reg = SUBREG_REG (reg);
1420 if (GET_CODE (reg) != REG)
1423 regno = REGNO (reg);
1425 /* Either this is one of the max_allocno pseudo regs not allocated,
1426 or it is or has a hardware reg. First handle the pseudo-regs. */
1427 if (regno >= FIRST_PSEUDO_REGISTER)
1429 if (reg_allocno[regno] >= 0)
1430 record_one_conflict (regno);
1433 if (reg_renumber[regno] >= 0)
1434 regno = reg_renumber[regno];
1436 /* Handle hardware regs (and pseudos allocated to hard regs). */
1437 if (regno < FIRST_PSEUDO_REGISTER && ! fixed_regs[regno])
1439 register int last = regno + HARD_REGNO_NREGS (regno, GET_MODE (reg));
1440 while (regno < last)
1442 record_one_conflict (regno);
1448 /* Mark REG as being dead (following the insn being scanned now).
1449 Store a 0 in regs_live or allocnos_live for this register. */
1452 mark_reg_death (reg)
1455 register int regno = REGNO (reg);
1457 /* Either this is one of the max_allocno pseudo regs not allocated,
1458 or it is a hardware reg. First handle the pseudo-regs. */
1459 if (regno >= FIRST_PSEUDO_REGISTER)
1461 if (reg_allocno[regno] >= 0)
1462 CLEAR_ALLOCNO_LIVE (reg_allocno[regno]);
1465 /* For pseudo reg, see if it has been assigned a hardware reg. */
1466 if (reg_renumber[regno] >= 0)
1467 regno = reg_renumber[regno];
1469 /* Handle hardware regs (and pseudos allocated to hard regs). */
1470 if (regno < FIRST_PSEUDO_REGISTER && ! fixed_regs[regno])
1472 /* Pseudo regs already assigned hardware regs are treated
1473 almost the same as explicit hardware regs. */
1474 register int last = regno + HARD_REGNO_NREGS (regno, GET_MODE (reg));
1475 while (regno < last)
1477 CLEAR_HARD_REG_BIT (hard_regs_live, regno);
1483 /* Mark hard reg REGNO as currently live, assuming machine mode MODE
1484 for the value stored in it. MODE determines how many consecutive
1485 registers are actually in use. Do not record conflicts;
1486 it is assumed that the caller will do that. */
1489 mark_reg_live_nc (regno, mode)
1491 enum machine_mode mode;
1493 register int last = regno + HARD_REGNO_NREGS (regno, mode);
1494 while (regno < last)
1496 SET_HARD_REG_BIT (hard_regs_live, regno);
1501 /* Try to set a preference for an allocno to a hard register.
1502 We are passed DEST and SRC which are the operands of a SET. It is known
1503 that SRC is a register. If SRC or the first operand of SRC is a register,
1504 try to set a preference. If one of the two is a hard register and the other
1505 is a pseudo-register, mark the preference.
1507 Note that we are not as aggressive as local-alloc in trying to tie a
1508 pseudo-register to a hard register. */
1511 set_preference (dest, src)
1514 int src_regno, dest_regno;
1515 /* Amount to add to the hard regno for SRC, or subtract from that for DEST,
1516 to compensate for subregs in SRC or DEST. */
1521 if (GET_RTX_FORMAT (GET_CODE (src))[0] == 'e')
1522 src = XEXP (src, 0), copy = 0;
1524 /* Get the reg number for both SRC and DEST.
1525 If neither is a reg, give up. */
1527 if (GET_CODE (src) == REG)
1528 src_regno = REGNO (src);
1529 else if (GET_CODE (src) == SUBREG && GET_CODE (SUBREG_REG (src)) == REG)
1531 src_regno = REGNO (SUBREG_REG (src));
1532 offset += SUBREG_WORD (src);
1537 if (GET_CODE (dest) == REG)
1538 dest_regno = REGNO (dest);
1539 else if (GET_CODE (dest) == SUBREG && GET_CODE (SUBREG_REG (dest)) == REG)
1541 dest_regno = REGNO (SUBREG_REG (dest));
1542 offset -= SUBREG_WORD (dest);
1547 /* Convert either or both to hard reg numbers. */
1549 if (reg_renumber[src_regno] >= 0)
1550 src_regno = reg_renumber[src_regno];
1552 if (reg_renumber[dest_regno] >= 0)
1553 dest_regno = reg_renumber[dest_regno];
1555 /* Now if one is a hard reg and the other is a global pseudo
1556 then give the other a preference. */
1558 if (dest_regno < FIRST_PSEUDO_REGISTER && src_regno >= FIRST_PSEUDO_REGISTER
1559 && reg_allocno[src_regno] >= 0)
1561 dest_regno -= offset;
1562 if (dest_regno >= 0 && dest_regno < FIRST_PSEUDO_REGISTER)
1565 SET_REGBIT (hard_reg_copy_preferences,
1566 reg_allocno[src_regno], dest_regno);
1568 SET_REGBIT (hard_reg_preferences,
1569 reg_allocno[src_regno], dest_regno);
1570 for (i = dest_regno;
1571 i < dest_regno + HARD_REGNO_NREGS (dest_regno, GET_MODE (dest));
1573 SET_REGBIT (hard_reg_full_preferences, reg_allocno[src_regno], i);
1577 if (src_regno < FIRST_PSEUDO_REGISTER && dest_regno >= FIRST_PSEUDO_REGISTER
1578 && reg_allocno[dest_regno] >= 0)
1580 src_regno += offset;
1581 if (src_regno >= 0 && src_regno < FIRST_PSEUDO_REGISTER)
1584 SET_REGBIT (hard_reg_copy_preferences,
1585 reg_allocno[dest_regno], src_regno);
1587 SET_REGBIT (hard_reg_preferences,
1588 reg_allocno[dest_regno], src_regno);
1590 i < src_regno + HARD_REGNO_NREGS (src_regno, GET_MODE (src));
1592 SET_REGBIT (hard_reg_full_preferences, reg_allocno[dest_regno], i);
1597 /* Indicate that hard register number FROM was eliminated and replaced with
1598 an offset from hard register number TO. The status of hard registers live
1599 at the start of a basic block is updated by replacing a use of FROM with
1603 mark_elimination (from, to)
1608 for (i = 0; i < n_basic_blocks; i++)
1610 register regset r = BASIC_BLOCK (i)->global_live_at_start;
1611 if (REGNO_REG_SET_P (r, from))
1613 CLEAR_REGNO_REG_SET (r, from);
1614 SET_REGNO_REG_SET (r, to);
1619 /* Used for communication between the following functions. Holds the
1620 current life information. */
1621 static regset live_relevant_regs;
1623 /* Record in live_relevant_regs that register REG became live. This
1624 is called via note_stores. */
1626 reg_becomes_live (reg, setter)
1628 rtx setter ATTRIBUTE_UNUSED;
1632 if (GET_CODE (reg) == SUBREG)
1633 reg = SUBREG_REG (reg);
1635 if (GET_CODE (reg) != REG)
1638 regno = REGNO (reg);
1639 if (regno < FIRST_PSEUDO_REGISTER)
1641 int nregs = HARD_REGNO_NREGS (regno, GET_MODE (reg));
1643 SET_REGNO_REG_SET (live_relevant_regs, regno++);
1645 else if (reg_renumber[regno] >= 0)
1646 SET_REGNO_REG_SET (live_relevant_regs, regno);
1649 /* Record in live_relevant_regs that register REGNO died. */
1651 reg_dies (regno, mode)
1653 enum machine_mode mode;
1655 if (regno < FIRST_PSEUDO_REGISTER)
1657 int nregs = HARD_REGNO_NREGS (regno, mode);
1659 CLEAR_REGNO_REG_SET (live_relevant_regs, regno++);
1662 CLEAR_REGNO_REG_SET (live_relevant_regs, regno);
1665 /* Walk the insns of the current function and build reload_insn_chain,
1666 and record register life information. */
1668 build_insn_chain (first)
1671 struct insn_chain **p = &reload_insn_chain;
1672 struct insn_chain *prev = 0;
1675 live_relevant_regs = ALLOCA_REG_SET ();
1677 for (; first; first = NEXT_INSN (first))
1679 struct insn_chain *c;
1681 if (first == BLOCK_HEAD (b))
1684 CLEAR_REG_SET (live_relevant_regs);
1685 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
1686 if (REGNO_REG_SET_P (BASIC_BLOCK (b)->global_live_at_start, i)
1687 && ! TEST_HARD_REG_BIT (eliminable_regset, i))
1688 SET_REGNO_REG_SET (live_relevant_regs, i);
1690 for (; i < max_regno; i++)
1691 if (reg_renumber[i] >= 0
1692 && REGNO_REG_SET_P (BASIC_BLOCK (b)->global_live_at_start, i))
1693 SET_REGNO_REG_SET (live_relevant_regs, i);
1696 if (GET_CODE (first) != NOTE && GET_CODE (first) != BARRIER)
1698 c = new_insn_chain ();
1706 COPY_REG_SET (c->live_before, live_relevant_regs);
1708 if (GET_RTX_CLASS (GET_CODE (first)) == 'i')
1712 /* Mark the death of everything that dies in this instruction. */
1714 for (link = REG_NOTES (first); link; link = XEXP (link, 1))
1715 if (REG_NOTE_KIND (link) == REG_DEAD
1716 && GET_CODE (XEXP (link, 0)) == REG)
1717 reg_dies (REGNO (XEXP (link, 0)), GET_MODE (XEXP (link, 0)));
1719 /* Mark everything born in this instruction as live. */
1721 note_stores (PATTERN (first), reg_becomes_live);
1724 /* Remember which registers are live at the end of the insn, before
1725 killing those with REG_UNUSED notes. */
1726 COPY_REG_SET (c->live_after, live_relevant_regs);
1728 if (GET_RTX_CLASS (GET_CODE (first)) == 'i')
1732 /* Mark anything that is set in this insn and then unused as dying. */
1734 for (link = REG_NOTES (first); link; link = XEXP (link, 1))
1735 if (REG_NOTE_KIND (link) == REG_UNUSED
1736 && GET_CODE (XEXP (link, 0)) == REG)
1737 reg_dies (REGNO (XEXP (link, 0)), GET_MODE (XEXP (link, 0)));
1741 if (first == BLOCK_END (b))
1744 /* Stop after we pass the end of the last basic block. Verify that
1745 no real insns are after the end of the last basic block.
1747 We may want to reorganize the loop somewhat since this test should
1748 always be the right exit test. */
1749 if (b == n_basic_blocks)
1751 for (first = NEXT_INSN (first) ; first; first = NEXT_INSN (first))
1752 if (GET_RTX_CLASS (GET_CODE (first)) == 'i'
1753 && GET_CODE (PATTERN (first)) != USE)
1758 FREE_REG_SET (live_relevant_regs);
1762 /* Print debugging trace information if -dg switch is given,
1763 showing the information on which the allocation decisions are based. */
1766 dump_conflicts (file)
1770 register int has_preferences;
1773 for (i = 0; i < max_allocno; i++)
1775 if (reg_renumber[allocno_reg[allocno_order[i]]] >= 0)
1779 fprintf (file, ";; %d regs to allocate:", nregs);
1780 for (i = 0; i < max_allocno; i++)
1783 if (reg_renumber[allocno_reg[allocno_order[i]]] >= 0)
1785 fprintf (file, " %d", allocno_reg[allocno_order[i]]);
1786 for (j = 0; j < max_regno; j++)
1787 if (reg_allocno[j] == allocno_order[i]
1788 && j != allocno_reg[allocno_order[i]])
1789 fprintf (file, "+%d", j);
1790 if (allocno_size[allocno_order[i]] != 1)
1791 fprintf (file, " (%d)", allocno_size[allocno_order[i]]);
1793 fprintf (file, "\n");
1795 for (i = 0; i < max_allocno; i++)
1798 fprintf (file, ";; %d conflicts:", allocno_reg[i]);
1799 for (j = 0; j < max_allocno; j++)
1800 if (CONFLICTP (i, j) || CONFLICTP (j, i))
1801 fprintf (file, " %d", allocno_reg[j]);
1802 for (j = 0; j < FIRST_PSEUDO_REGISTER; j++)
1803 if (TEST_HARD_REG_BIT (hard_reg_conflicts[i], j))
1804 fprintf (file, " %d", j);
1805 fprintf (file, "\n");
1807 has_preferences = 0;
1808 for (j = 0; j < FIRST_PSEUDO_REGISTER; j++)
1809 if (TEST_HARD_REG_BIT (hard_reg_preferences[i], j))
1810 has_preferences = 1;
1812 if (! has_preferences)
1814 fprintf (file, ";; %d preferences:", allocno_reg[i]);
1815 for (j = 0; j < FIRST_PSEUDO_REGISTER; j++)
1816 if (TEST_HARD_REG_BIT (hard_reg_preferences[i], j))
1817 fprintf (file, " %d", j);
1818 fprintf (file, "\n");
1820 fprintf (file, "\n");
1824 dump_global_regs (file)
1829 fprintf (file, ";; Register dispositions:\n");
1830 for (i = FIRST_PSEUDO_REGISTER, j = 0; i < max_regno; i++)
1831 if (reg_renumber[i] >= 0)
1833 fprintf (file, "%d in %d ", i, reg_renumber[i]);
1835 fprintf (file, "\n");
1838 fprintf (file, "\n\n;; Hard regs used: ");
1839 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
1840 if (regs_ever_live[i])
1841 fprintf (file, " %d", i);
1842 fprintf (file, "\n\n");