2 * Copyright (C) 1995-2007 University of Karlsruhe. All right reserved.
4 * This file is part of libFirm.
6 * This file may be distributed and/or modified under the terms of the
7 * GNU General Public License version 2 as published by the Free Software
8 * Foundation and appearing in the file LICENSE.GPL included in the
9 * packaging of this file.
11 * Licensees holding valid libFirm Professional Edition licenses may use
12 * this file in accordance with the libFirm Commercial License.
13 * Agreement provided with the Software.
15 * This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
16 * WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR
22 * @brief Beladys spillalgorithm version 2.
23 * @author Sebastian Hack, Matthias Braun, Daniel Grund
27 * The main differences to the original Belady are:
28 * - The workset is empty at the start of a block
29 * There is no attempt to fill it with variables which
30 * are not used in the block.
31 * - There is a global pass which tries to use the remaining
32 * capacity of the blocks to let global variables live through
43 #include "irnodeset.h"
45 #include "irprintf_t.h"
51 #include "iredges_t.h"
52 #include "irphase_t.h"
60 #include "bespillbelady.h"
61 #include "besched_t.h"
65 #include "bechordal_t.h"
66 #include "bespilloptions.h"
67 #include "beloopana.h"
71 #include <libcore/lc_opts.h>
72 #include <libcore/lc_opts_enum.h>
73 #include <libcore/lc_timing.h>
82 #define DBG_WORKSET 128
83 #define DBG_GLOBAL 256
85 #define ALREADY_SPILLED_FACTOR 2
88 #define LIVE_END (DEAD-1)
89 #define REMAT_DIST (DEAD-2)
91 static int already_spilled_factor = 2;
92 static int remat_live_range_ext = 1;
93 static int global_pass_enabled = 1;
95 static const lc_opt_table_entry_t options[] = {
96 LC_OPT_ENT_ENUM_INT ("asf", "already spilled factor", &already_spilled_factor),
97 LC_OPT_ENT_BOOL ("remat", "rematerializable ops get infinite long live ranges", &remat_live_range_ext),
98 LC_OPT_ENT_BOOL ("global", "rematerializable ops get infinite long live ranges", &global_pass_enabled),
102 DEBUG_ONLY(static firm_dbg_module_t *dbg = NULL;)
105 * An association between a node and a point in time.
107 typedef struct _loc_t {
108 ir_node *irn; /**< A node. */
109 unsigned time; /**< A use time.
110 In the global pass this is used
111 as the version number and not as a time.
112 Only to save space...
116 typedef struct _workset_t {
117 int len; /**< current length */
118 loc_t vals[0]; /**< inlined array of the values/distances in this working set */
121 typedef struct _belady_env_t {
124 const arch_env_t *arch;
125 const arch_register_class_t *cls;
129 ir_node **blocks; /**< Array of all blocks. */
130 int n_blocks; /**< Number of blocks in the graph. */
131 int n_regs; /**< number of regs in this reg-class */
132 workset_t *ws; /**< the main workset used while processing a block. ob-allocated */
133 ir_node *instr; /**< current instruction */
134 int instr_nr; /**< current instruction number (relative to block start) */
136 spill_env_t *senv; /**< see bespill.h */
137 bitset_t *spilled; /**< bitset to keep all the irns which have already been spilled. */
141 static int loc_compare(const void *a, const void *b)
145 return (p->time > q->time) - (p->time < q->time);
148 static INLINE void workset_print(const workset_t *w)
152 for(i = 0; i < w->len; ++i) {
153 ir_fprintf(stderr, "%+F %d\n", w->vals[i].irn, w->vals[i].time);
158 * Alloc a new workset on obstack @p ob with maximum size @p max
160 static INLINE workset_t *new_workset(belady_env_t *env, struct obstack *ob) {
162 size_t size = sizeof(*res) + (env->n_regs)*sizeof(res->vals[0]);
163 res = obstack_alloc(ob, size);
164 memset(res, 0, size);
169 * Alloc a new instance on obstack and make it equal to @param ws
171 static INLINE workset_t *workset_clone(belady_env_t *env, struct obstack *ob, workset_t *ws) {
173 size_t size = sizeof(*res) + (env->n_regs)*sizeof(res->vals[0]);
174 res = obstack_alloc(ob, size);
175 memcpy(res, ws, size);
180 * Do NOT alloc anything. Make @param tgt equal to @param src.
181 * returns @param tgt for convenience
183 static INLINE workset_t *workset_copy(belady_env_t *env, workset_t *tgt, workset_t *src) {
184 size_t size = sizeof(*src) + (env->n_regs)*sizeof(src->vals[0]);
185 memcpy(tgt, src, size);
190 * Overwrites the current content array of @param ws with the
191 * @param count locations given at memory @param locs.
192 * Set the length of @param ws to count.
194 static INLINE void workset_bulk_fill(workset_t *workset, int count, const loc_t *locs) {
195 workset->len = count;
196 memcpy(&(workset->vals[0]), locs, count * sizeof(locs[0]));
200 * Inserts the value @p val into the workset, iff it is not
201 * already contained. The workset must not be full.
203 static INLINE void workset_insert(belady_env_t *env, workset_t *ws, ir_node *val) {
205 /* check for current regclass */
206 if (!arch_irn_consider_in_reg_alloc(env->arch, env->cls, val)) {
207 DBG((dbg, DBG_WORKSET, "Skipped %+F\n", val));
211 /* check if val is already contained */
212 for(i=0; i<ws->len; ++i)
213 if (ws->vals[i].irn == val)
217 assert(ws->len < env->n_regs && "Workset already full!");
218 ws->vals[ws->len++].irn = val;
222 * Removes all entries from this workset
224 static INLINE void workset_clear(workset_t *ws) {
229 * Removes the value @p val from the workset if present.
231 static INLINE void workset_remove(workset_t *ws, ir_node *val) {
233 for(i=0; i<ws->len; ++i) {
234 if (ws->vals[i].irn == val) {
235 ws->vals[i] = ws->vals[--ws->len];
241 static INLINE int workset_get_index(const workset_t *ws, const ir_node *val) {
243 for(i=0; i<ws->len; ++i) {
244 if (ws->vals[i].irn == val)
252 * Iterates over all values in the working set.
253 * @p ws The workset to iterate
254 * @p v A variable to put the current value in
255 * @p i An integer for internal use
257 #define workset_foreach(ws, v, i) for(i=0; \
258 v=(i < ws->len) ? ws->vals[i].irn : NULL, i < ws->len; \
261 #define workset_set_time(ws, i, t) (ws)->vals[i].time=t
262 #define workset_get_time(ws, i) (ws)->vals[i].time
263 #define workset_set_length(ws, length) (ws)->len = length
264 #define workset_get_length(ws) ((ws)->len)
265 #define workset_get_val(ws, i) ((ws)->vals[i].irn)
266 #define workset_sort(ws) qsort((ws)->vals, (ws)->len, sizeof((ws)->vals[0]), loc_compare);
267 #define workset_contains(ws, n) (workset_get_index(ws, n) >= 0)
269 typedef struct _block_info_t {
272 workset_t *ws_start, *ws_end;
276 ir_node *first_non_in; /**< First node in block which is not a phi. */
277 ir_node *last_ins; /**< The instruction before which end of
278 block reloads will be inserted. */
280 workset_t *entrance_reg; /**< That set will contain all values
281 transported into the block which
282 are used before they are displaced.
283 That means, we later have to care to
284 bring them into the block in a register
285 or reload them at the entry of the block. */
287 int pressure; /**< The amount of registers which remain free
288 in this block. This capacity can be used to let
289 global variables, transported into other blocks,
290 live through this block. */
292 double exec_freq; /**< The execution frequency of this block. */
295 static INLINE void *new_block_info(belady_env_t *bel, int id)
297 ir_node *bl = bel->blocks[id];
298 block_info_t *res = obstack_alloc(&bel->ob, sizeof(*res));
299 memset(res, 0, sizeof(res[0]));
300 res->first_non_in = NULL;
301 res->last_ins = NULL;
305 res->entrance_reg = new_workset(bel, &bel->ob);
306 res->exec_freq = get_block_execfreq(bel->ef, bl);
307 set_irn_link(bl, res);
311 #define get_block_info(block) ((block_info_t *)get_irn_link(block))
312 #define set_block_info(block, info) set_irn_link(block, info)
314 static INLINE ir_node *block_info_get_last_ins(block_info_t *bi)
317 bi->last_ins = be_get_end_of_block_insertion_point(bi->bl);
322 typedef struct _next_use_t {
323 unsigned is_first_use : 1; /**< Indicate that this use is the first
324 in the block. Needed to identify
325 transport in values for the global
327 int step; /**< The time step of the use. */
329 struct _next_use_t *next; /**< The next use int this block
333 static void *next_use_init(ir_phase *phase, ir_node *irn, void *old)
341 static void build_next_uses(block_info_t *bi)
345 sched_renumber(bi->bl);
347 phase_init(&bi->next_uses, "next uses", bi->bel->irg, PHASE_DEFAULT_GROWTH, next_use_init, NULL);
348 sched_foreach_reverse(bi->bl, irn) {
354 for (i = get_irn_arity(irn) - 1; i >= 0; --i) {
355 ir_node *op = get_irn_n(irn, i);
356 next_use_t *curr = phase_get_irn_data(&bi->next_uses, op);
357 next_use_t *use = phase_alloc(&bi->next_uses, sizeof(use[0]));
359 use->is_first_use = 1;
360 use->step = sched_get_time_step(irn);
365 curr->is_first_use = 0;
367 phase_set_irn_data(&bi->next_uses, op, use);
372 #define get_current_use(bi, irn) phase_get_irn_data(&(bi)->next_uses, (irn))
374 static INLINE void advance_current_use(block_info_t *bi, const ir_node *irn)
376 next_use_t *use = get_current_use(bi, irn);
379 phase_set_irn_data(&bi->next_uses, irn, use->next);
382 static INLINE unsigned get_curr_distance(block_info_t *bi, const ir_node *irn, int is_usage)
384 belady_env_t *env = bi->bel;
385 next_use_t *use = get_current_use(bi, irn);
386 int curr_step = sched_get_time_step(irn);
387 int flags = arch_irn_get_flags(env->arch, irn);
389 assert(!(flags & arch_irn_flags_ignore));
391 /* We have to keep nonspillable nodes in the workingset */
392 if(flags & arch_irn_flags_dont_spill)
395 if (!is_usage && use && use->step == curr_step)
399 unsigned res = use->step - curr_step;
401 assert(use->step >= curr_step);
404 if (remat_live_range_ext && be_is_rematerializable(env->senv, irn, use->irn))
406 else if (bitset_contains_irn(env->spilled, irn))
407 res *= already_spilled_factor;
413 return be_is_live_end(env->lv, bi->bl, irn) ? LIVE_END : DEAD;
416 static INLINE int is_local_phi(const ir_node *bl, const ir_node *irn)
418 return is_Phi(irn) && get_nodes_block(irn) == bl;
422 * Check, if the value is something that is transported into a block.
423 * That is, the value is defined elsewhere or defined by a Phi in the block.
424 * @param env The belady environment.
425 * @param bl The block in question.
426 * @param irn The node in question.
427 * @return 1, if node is something transported into @p bl, 0 if not.
428 * @note The function will only give correct answers in the case
429 * where @p irn is unsed in the block @p bl which is always
430 * the case in our usage scenario.
432 static INLINE int is_transport_in(const ir_node *bl, const ir_node *irn)
434 return is_local_phi(bl, irn) || get_nodes_block(irn) != bl;
438 * Performs the actions necessary to grant the request that:
439 * - new_vals can be held in registers
440 * - as few as possible other values are disposed
441 * - the worst values get disposed
443 * @p is_usage indicates that the values in new_vals are used (not defined)
444 * In this case reloads must be performed
446 static void displace(block_info_t *bi, workset_t *new_vals, int is_usage) {
447 belady_env_t *env = bi->bel;
448 workset_t *ws = env->ws;
449 ir_node **to_insert = alloca(env->n_regs * sizeof(to_insert[0]));
451 int i, len, max_allowed, demand, iter;
455 1. Identify the number of needed slots and the values to reload
458 workset_foreach(new_vals, val, iter) {
459 /* mark value as used */
461 if (! workset_contains(ws, val)) {
462 DBG((dbg, DBG_DECIDE, " insert %+F\n", val));
463 to_insert[demand++] = val;
465 int insert_reload = 1;
466 next_use_t *use = get_current_use(bi, val);
469 * if we use a value which is transported in this block, i.e. a
470 * phi defined here or a live in, for the first time, we check
471 * if there is room for that guy to survive from the block's
472 * entrance to here or not.
475 assert(sched_get_time_step(env->instr) == use->step);
476 if (is_transport_in(bi->bl, val) && use->is_first_use) {
477 DBG((dbg, DBG_DECIDE, "entrance node %+F, pressure %d:\n", val, bi->pressure));
478 if (bi->pressure < env->n_regs) {
479 workset_insert(env, bi->entrance_reg, val);
482 DBG((dbg, DBG_DECIDE, "... no reload. must be considered at block start\n"));
487 bitset_add_irn(env->spilled, val);
488 DBG((dbg, DBG_SPILL, "Reload %+F before %+F\n", val, env->instr));
489 be_add_reload(env->senv, val, env->instr, env->cls, 1);
493 assert(is_usage || "Defined value already in workset?!?");
494 DBG((dbg, DBG_DECIDE, " skip %+F\n", val));
497 DBG((dbg, DBG_DECIDE, " demand = %d\n", demand));
500 2. Make room for at least 'demand' slots
502 len = workset_get_length(ws);
503 max_allowed = env->n_regs - demand;
505 /* Only make more free room if we do not have enough */
506 if (len > max_allowed) {
507 DBG((dbg, DBG_DECIDE, " disposing %d values\n", len - max_allowed));
509 /* get current next-use distance */
510 for (i = 0; i < ws->len; ++i) {
511 ir_node *val = workset_get_val(ws, i);
512 unsigned dist = get_curr_distance(bi, val, is_usage);
513 workset_set_time(ws, i, dist);
516 /* sort entries by increasing nextuse-distance*/
519 /* kill the last 'demand' entries in the array */
520 workset_set_length(ws, max_allowed);
524 3. Insert the new values into the workset
525 Also, we update the pressure in the block info.
526 That is important for the global pass to decide
527 how many values can live through the block.
529 for (i = 0; i < demand; ++i)
530 workset_insert(env, env->ws, to_insert[i]);
532 bi->pressure = MAX(bi->pressure, workset_get_length(env->ws));
536 * For the given block @p block, decide for each values
537 * whether it is used from a register or is reloaded
540 static void belady(belady_env_t *env, int id) {
541 block_info_t *block_info = new_block_info(env, id);
542 const ir_node *block = block_info->bl;
543 void *obst_state = obstack_base(&env->ob);
549 DBG((dbg, DBG_WSETS, "Processing %+F...\n", block_info->bl));
550 new_vals = new_workset(env, &env->ob);
551 workset_clear(env->ws);
553 /* build the next use information for this block. */
554 build_next_uses(block_info);
557 block_info->first_non_in = NULL;
559 /* process the block from start to end */
560 sched_foreach(block, irn) {
562 assert(workset_get_length(env->ws) <= env->n_regs && "Too much values in workset!");
564 /* projs are handled with the tuple value.
565 * Phis are no real instr (see insert_starters())
566 * instr_nr does not increase */
567 if (is_Proj(irn) || is_Phi(irn)) {
568 DBG((dbg, DBG_DECIDE, " ...%+F skipped\n", irn));
571 DBG((dbg, DBG_DECIDE, " ...%+F\n", irn));
573 if (!block_info->first_non_in)
574 block_info->first_non_in = irn;
576 /* set instruction in the workset */
579 /* allocate all values _used_ by this instruction */
580 workset_clear(new_vals);
581 for(i = 0, arity = get_irn_arity(irn); i < arity; ++i) {
582 workset_insert(env, new_vals, get_irn_n(irn, i));
584 displace(block_info, new_vals, 1);
587 * set all used variables to the next use in their next_use_t list
588 * Also, kill all dead variables from the workset. They are only
589 * augmenting the pressure. Note, that a variable is dead
590 * if it has no further use in this block and is *not* live end
592 for(i = 0, arity = get_irn_arity(irn); i < arity; ++i) {
593 ir_node *op = get_irn_n(irn, i);
594 next_use_t *use = get_current_use(block_info, op);
597 if (!use->next && !be_is_live_end(env->lv, block, op))
598 workset_remove(env->ws, op);
600 advance_current_use(block_info, op);
603 /* allocate all values _defined_ by this instruction */
604 workset_clear(new_vals);
605 if (get_irn_mode(irn) == mode_T) { /* special handling for tuples and projs */
606 const ir_edge_t *edge;
608 foreach_out_edge(irn, edge) {
609 ir_node *proj = get_edge_src_irn(edge);
610 workset_insert(env, new_vals, proj);
613 workset_insert(env, new_vals, irn);
615 displace(block_info, new_vals, 0);
620 phase_free(&block_info->next_uses);
621 obstack_free(&env->ob, obst_state);
623 /* Remember end-workset for this block */
624 block_info->ws_end = workset_clone(env, &env->ob, env->ws);
625 DBG((dbg, DBG_WSETS, "End workset for %+F:\n", block));
626 workset_foreach(block_info->ws_end, irn, iter)
627 DBG((dbg, DBG_WSETS, " %+F (%u)\n", irn, workset_get_time(block_info->ws_end, iter)));
628 DBG((dbg, DBG_WSETS, "Max pressure in block: %d\n", block_info->pressure));
633 |_ _| |__ ___ __ _| | ___ | |__ __ _| | | _ \ __ _ _ __| |_
634 | | | '_ \ / _ \ / _` | |/ _ \| '_ \ / _` | | | |_) / _` | '__| __|
635 | | | | | | __/ | (_| | | (_) | |_) | (_| | | | __/ (_| | | | |_
636 |_| |_| |_|\___| \__, |_|\___/|_.__/ \__,_|_| |_| \__,_|_| \__|
641 #define workset_set_version(ws, i, t) ((ws)->vals[(i)].time = (t))
642 #define workset_get_version(ws, i) ((ws)->vals[(i)].time)
644 #define ver_oldest (0)
645 #define ver_youngest ((unsigned) -1)
646 #define ver_make_newer(v) ((v) + 1)
647 #define ver_is_older(v, w) ((v) < (w))
648 #define ver_is_younger(v, w) ((v) > (w))
650 static int block_freq_gt(const void *a, const void *b)
652 const ir_node * const *p = a;
653 const ir_node * const *q = b;
654 block_info_t *pi = get_block_info(*p);
655 block_info_t *qi = get_block_info(*q);
656 double diff = qi->exec_freq - pi->exec_freq;
657 return (diff > 0) - (diff < 0);
666 typedef struct _block_state_t {
667 struct _block_state_t *next;
668 struct _block_state_t *next_intern;
671 workset_t *end_state;
674 typedef struct _irn_action_t {
675 struct _irn_action_t *next;
681 typedef struct _global_end_state_t {
689 unsigned *bs_tops_vers;
690 block_state_t **bs_tops;
691 block_state_t *bs_top;
692 irn_action_t *ia_top;
693 } global_end_state_t;
697 block_state_t *bs_top;
698 irn_action_t *ia_top;
701 static INLINE block_state_t *get_block_state(global_end_state_t *ges, block_info_t *bi)
704 assert(!ver_is_younger(ges->bs_tops_vers[id], ges->version));
705 return ver_is_older(ges->bs_tops_vers[id], ges->version) ? NULL : ges->bs_tops[bi->id];
708 static INLINE const workset_t *get_end_state(global_end_state_t *ges, block_info_t *bi)
710 block_state_t *bs = get_block_state(ges, bi);
711 return bs ? bs->end_state : bi->ws_end;
714 static block_state_t *new_block_state(global_end_state_t *ges, block_info_t *bi)
716 block_state_t *bs = get_block_state(ges, bi);
717 block_state_t *nw = obstack_alloc(&ges->obst, sizeof(nw[0]));
719 nw->next_intern = bs;
720 nw->next = ges->bs_top;
724 nw->pressure = bs->pressure;
725 nw->end_state = workset_clone(ges->env, &ges->obst, bs->end_state);
728 nw->pressure = bi->pressure;
729 nw->end_state = workset_clone(ges->env, &ges->obst, bi->ws_end);
733 ges->bs_tops[bi->id] = nw;
734 ges->bs_tops_vers[bi->id] = ges->version;
738 static irn_action_t *new_irn_action(global_end_state_t *ges, ir_node *irn, const ir_node *bl)
740 irn_action_t *ia = obstack_alloc(&ges->obst, sizeof(ia[0]));
744 ia->act = irn_act_none;
745 ia->next = ges->ia_top;
750 static INLINE rollback_info_t trans_begin(global_end_state_t *ges)
753 rb.obst_level = obstack_base(&ges->obst);
754 rb.bs_top = ges->bs_top;
755 rb.ia_top = ges->ia_top;
759 static INLINE void trans_rollback(global_end_state_t *ges, rollback_info_t *rb)
763 /* unwind all the stacks indiced with the block number */
764 for (bs = ges->bs_top; bs != rb->bs_top; bs = bs->next) {
765 unsigned id = bs->bi->id;
766 ges->bs_tops[id] = bs->next_intern;
769 ges->ia_top = rb->ia_top;
770 ges->bs_top = rb->bs_top;
771 obstack_free(&ges->obst, rb->obst_level);
775 static double can_bring_in(global_end_state_t *ges, ir_node *bl, ir_node *irn, double limit, int level);
777 static double can_make_available_at_end(global_end_state_t *ges, ir_node *bl, ir_node *irn, double limit, int level)
779 block_info_t *bi = get_block_info(bl);
780 const workset_t *end = get_end_state(ges, bi);
784 DBG((dbg, DBG_GLOBAL, "\t%2Dcan make avail %+F at end of %+F\n", level, irn, bl));
787 * to make the value available at end,
788 * we have several cases here.
790 * - we already visited that block.
791 * - If the value is in the final end set, return 0.
792 * somebody else already allocated it there.
793 * - If not and the final end set is already full,
794 * we cannot make the value available at the end
795 * of this block. return INFINITY.
796 * - Else (value not in final end set and there is room):
797 * 1) The value is in a register at the end of the local Belady pass.
798 * Allocate a slot in the final end set and return 0.
799 * 2) The value is not in the Belady end set:
800 * If the block's capacity is < k then check what it costs
801 * to transport the value from upper blocks to this block.
802 * Compare that against the reload cost in this block. If
803 * cheaper, do the other thing. If not, reload it here.
806 /* if the end set contains it already, it is in a reg and it costs nothing
807 * to load it to one. */
808 index = workset_get_index(end, irn);
810 unsigned ver = workset_get_version(end, index);
811 DBG((dbg, DBG_GLOBAL, "\t%2Dnode is in the end set and is %s fixed\n",
812 level, ver_is_older(ver, ges->version) ? "already" : "not yet"));
815 * if the version is older, the value is already fixed
816 * and cannot be removed from the end set.
818 * If not, we will create a new block state for that block since
819 * we modify it by giving the end state a new version.
821 if (ver_is_younger(ver, ges->version)) {
822 block_state_t *bs = new_block_state(ges, bi);
823 workset_set_version(bs->end_state, index, ges->version);
831 * Now we have two options:
832 * 1) Reload the value at the end of the block.
833 * Therefore, perhaps, we have to erase another one from the workset.
834 * This may only be done if it has not been fixed.
835 * Since fixed means that a previous pass has decided that that value
836 * *has* to stay in the end set.
837 * 2) we can try, if the capacity of the block allows it, to let
838 * the value live through the block and make it available at
841 * First, we test the local (reload in this block) alternative
842 * and compare against the other alternative.
843 * Of course, we chose the cheaper one.
847 int n_regs = bi->bel->n_regs;
848 int len = workset_get_length(end);
855 * look if there is room in the end array
856 * for the variable. Note that this does not
857 * mean that the var can live through the block.
858 * There is just room at the *end*
861 DBG((dbg, DBG_GLOBAL, "\t%2Dthe end set has %d free slots\n", level, n_regs - len));
864 for (i = 0; i < len; ++i) {
865 unsigned ver = workset_get_version(end, i);
866 if (ver_is_younger(ver, ges->version))
871 DBG((dbg, DBG_GLOBAL, "\t%2D%+F (slot %d) can be erased from the end set\n",
872 level, end->vals[i].irn, i));
878 * finally there is some room. we can at least reload the value.
879 * but we will try to let ot live through anyhow.
882 irn_action_t *vs = new_irn_action(ges, irn, bi->bl);
883 block_state_t *bs = new_block_state(ges, bi);
884 workset_t *end = bs->end_state;
885 ir_node *ins_before = block_info_get_last_ins(bi);
886 double reload_here = be_get_reload_costs(bi->bel->senv, irn, ins_before);
887 int pressure_ok = bs->pressure < (unsigned) n_regs;
890 * No matter what we do, the value will be in the end set
891 * if the block from now on (of course only regarding the
892 * current state). Enter it and set the new length
895 end->vals[slot].irn = irn;
896 workset_set_version(end, slot, ges->version);
897 workset_set_length(end, MAX(workset_get_length(end), slot + 1));
899 vs->act = irn_act_reload;
902 DBG((dbg, DBG_GLOBAL, "\t%2Dthere is a free slot. capacity=%d, reload here=%f, pressure %s\n",
903 level, n_regs - bs->pressure, reload_here, pressure_ok ? "ok" : "insufficient"));
905 /* look if we can bring the value in. */
907 rollback_info_t rb = trans_begin(ges);
908 double new_limit = MIN(reload_here, limit);
910 vs->act = irn_act_live_through;
912 res = can_bring_in(ges, bl, irn, new_limit, level + 1);
915 * if bring in is too expensive re-adjust the pressure
916 * and roll back the state
918 if (res >= reload_here) {
920 vs->act = irn_act_reload;
921 trans_rollback(ges, &rb);
926 DBG((dbg, DBG_GLOBAL, "\t%2D%s\n", level,
927 vs->act == irn_act_reload ? "reloading" : "bringing in"));
932 DBG((dbg, DBG_GLOBAL, "\t%2D-> %f\n", level, res));
936 static double can_bring_in(global_end_state_t *ges, ir_node *bl, ir_node *irn, double limit, int level)
938 belady_env_t *env = ges->env;
939 double glob_costs = HUGE_VAL;
941 DBG((dbg, DBG_GLOBAL, "\t%2Dcan bring in (max %f) for %+F at block %+F\n", level, limit, irn, bl));
943 if (is_transport_in(bl, irn)) {
944 int i, n = get_irn_arity(bl);
945 ir_node **nodes = alloca(get_irn_arity(bl) * sizeof(nodes[0]));
946 rollback_info_t rb = trans_begin(ges);
950 for (i = 0; i < n; ++i) {
951 ir_node *pr = get_Block_cfgpred_block(bl, i);
952 ir_node *op = is_local_phi(bl, irn) ? get_irn_n(irn, i) : irn;
956 * there might by unknwons as operands of phis in that case
957 * we set the costs to zero, since they won't get spilled.
959 if (arch_irn_consider_in_reg_alloc(env->arch, env->cls, op))
960 c = can_make_available_at_end(ges, pr, op, limit - glob_costs, level + 1);
966 if (glob_costs >= limit) {
967 glob_costs = HUGE_VAL;
968 trans_rollback(ges, &rb);
975 DBG((dbg, DBG_GLOBAL, "\t%2D-> %f\n", level, glob_costs));
979 static void materialize_and_commit_end_state(global_end_state_t *ges)
981 belady_env_t *env = ges->env;
985 DBG((dbg, DBG_GLOBAL, "\tmaterializing\n"));
988 * Perform all the variable actions.
990 for (ia = ges->ia_top; ia != NULL; ia = ia->next) {
992 case irn_act_live_through:
993 if (is_local_phi(ia->bl, ia->irn)) {
994 bitset_add_irn(ges->succ_phis, ia->irn);
995 DBG((dbg, DBG_GLOBAL, "\t\tlive through phi kept alive: %+F\n", ia->irn));
999 be_add_reload_at_end(env->senv, ia->irn, ia->bl, env->cls, 1);
1000 DBG((dbg, DBG_GLOBAL, "\t\tadding reload of %+F at end of %+F\n", ia->irn, ia->bl));
1003 DBG((dbg, DBG_GLOBAL, "\t\t%+F is in the end set of %+F\n", ia->irn, ia->bl));
1008 * Commit the block end states
1010 for (bs = ges->bs_top; bs != NULL; bs = bs->next) {
1011 block_info_t *bi = bs->bi;
1013 if (!bitset_is_set(ges->committed, bi->id)) {
1014 DBG((dbg, DBG_GLOBAL, "\t\tcommiting workset of %+F with version %x\n", bi->bl, ges->version));
1015 // bes->bs->end_state->vals[idx].version = ges->version;
1016 workset_copy(env, bi->ws_end, bs->end_state);
1017 DBG((dbg, DBG_GLOBAL, "\t\told pressure: %d, new pressure: %d, end length: %d\n",
1018 bi->pressure, bs->pressure, workset_get_length(bs->end_state)));
1019 bi->pressure = bs->pressure;
1020 bitset_set(ges->committed, bi->id);
1024 /* clear the committed bitset. the next call is expecting it. */
1025 bitset_clear_all(ges->committed);
1029 * Examine all irns which shall be in regs at the beginning of the
1032 static void fix_block_borders(global_end_state_t *ges, ir_node *block) {
1033 block_info_t *bi = get_block_info(block);
1034 belady_env_t *env = ges->env;
1035 void *reset_level = obstack_base(&ges->obst);
1040 for (i = workset_get_length(bi->ws_end) - 1; i >= 0; --i)
1041 workset_set_version(bi->ws_end, i, ver_youngest);
1043 DBG((dbg, DBG_GLOBAL, "fixing block borders at %+F (%f)\n", block, bi->exec_freq));
1045 /* process all variables which shall be in a reg at
1046 * the beginning of the block in the order of the next use. */
1047 workset_foreach(bi->entrance_reg, irn, i) {
1048 double local_costs = be_get_reload_costs(env->senv, irn, bi->first_non_in);
1049 double bring_in_costs;
1051 /* reset the lists */
1055 DBG((dbg, DBG_GLOBAL, "\ttrans in var %+F, version %x\n", irn, ges->version));
1057 bring_in_costs = can_bring_in(ges, block, irn, local_costs, 1);
1059 DBG((dbg, DBG_GLOBAL, "\tbring in: %f, local: %f", bring_in_costs, local_costs));
1062 * we were not able to let the value arrive
1063 * in a register at the entrance of the block
1064 * or it is too costly, so we have to do the reload locally
1066 if (bring_in_costs >= local_costs) {
1067 DBG((dbg, DBG_GLOBAL, " -> do local reload\n"));
1068 be_add_reload(env->senv, irn, bi->first_non_in, env->cls, 1);
1071 * if the transport-in was a phi (that is actually used in block)
1072 * it will no longer remain and we have to spill it completely.
1074 if (is_local_phi(block, irn))
1075 bitset_add_irn(ges->succ_phis, irn);
1077 DBG((dbg, DBG_GLOBAL, " -> bring it in\n"));
1078 materialize_and_commit_end_state(ges);
1081 DBG((dbg, DBG_GLOBAL, "\n"));
1083 /* reset the obstack and create a new version. */
1084 obstack_free(&ges->obst, reset_level);
1085 ges->version = ver_make_newer(ges->version);
1089 static void global_assign(belady_env_t *env)
1091 global_end_state_t ges;
1095 * sort the blocks according to execution frequency.
1096 * That's not necessary for belady() but for the global pass later on.
1098 qsort(env->blocks, env->n_blocks, sizeof(env->blocks[0]), block_freq_gt);
1100 memset(&ges, 0, sizeof(ges));
1101 obstack_init(&ges.obst);
1103 ges.version = ver_make_newer(ver_oldest);
1104 ges.succ_phis = bitset_irg_obstack_alloc(&ges.obst, env->irg);
1105 ges.committed = bitset_obstack_alloc(&ges.obst, env->n_blocks);
1106 ges.bs_tops = obstack_alloc(&ges.obst, sizeof(ges.bs_tops[0]) * env->n_blocks);
1107 ges.bs_tops_vers = obstack_alloc(&ges.obst, sizeof(ges.bs_tops_vers[0]) * env->n_blocks);
1109 for (i = 0; i < env->n_blocks; ++i)
1110 ges.bs_tops_vers[i] = ver_oldest;
1112 for (i = 0; i < env->n_blocks; ++i)
1113 fix_block_borders(&ges, env->blocks[i]);
1116 * Now we spill phis which cannot be kept since they were replaced
1117 * by reloads at the block entrances.
1119 for (i = 0; i < env->n_blocks; ++i) {
1120 ir_node *bl = env->blocks[i];
1123 sched_foreach(bl, irn) {
1127 if (arch_irn_consider_in_reg_alloc(env->arch, env->cls, irn)
1128 && !bitset_contains_irn(ges.succ_phis, irn))
1129 be_spill_phi(env->senv, irn);
1134 static void collect_blocks(ir_node *bl, void *data)
1136 belady_env_t *env = data;
1138 obstack_ptr_grow(&env->ob, bl);
1142 * Do spilling for a register class on a graph using the belady heuristic.
1143 * In the transformed graph, the register pressure never exceeds the number
1144 * of available registers.
1146 * @param birg The backend graph
1147 * @param cls The register class to spill
1149 void be_spill_belady(be_irg_t *birg, const arch_register_class_t *cls)
1151 ir_graph *irg = be_get_birg_irg(birg);
1155 /* some special classes contain only ignore regs, nothing to do then */
1156 n_regs = cls->n_regs - be_put_ignore_regs(birg, cls, NULL);
1160 be_clear_links(irg);
1162 /* init belady env */
1163 obstack_init(&env.ob);
1165 env.arch = birg->main_env->arch_env;
1167 env.lv = be_get_birg_liveness(birg);
1168 env.n_regs = n_regs;
1169 env.ws = new_workset(&env, &env.ob);
1170 env.senv = be_new_spill_env(birg);
1171 env.ef = be_get_birg_exec_freq(birg);
1172 env.spilled = bitset_irg_obstack_alloc(&env.ob, irg);
1175 irg_block_walk_graph(irg, NULL, collect_blocks, &env);
1176 obstack_ptr_grow(&env.ob, NULL);
1177 env.blocks = obstack_finish(&env.ob);
1179 /* Fix high register pressure in blocks with belady algorithm */
1180 for (i = 0; i < env.n_blocks; ++i)
1183 global_assign(&env);
1185 /* Insert spill/reload nodes into the graph and fix usages */
1186 be_insert_spills_reloads(env.senv);
1189 be_delete_spill_env(env.senv);
1191 obstack_free(&env.ob, NULL);
1194 void be_init_spillbelady2(void)
1196 lc_opt_entry_t *be_grp = lc_opt_get_grp(firm_opt_get_root(), "be");
1197 lc_opt_entry_t *spill_grp = lc_opt_get_grp(be_grp, "spill");
1198 lc_opt_entry_t *bel2_grp = lc_opt_get_grp(spill_grp, "belady2");
1200 static be_spiller_t belady_spiller = {
1204 lc_opt_add_table(bel2_grp, options);
1205 be_register_spiller("belady2", &belady_spiller);
1206 FIRM_DBG_REGISTER(dbg, "firm.be.spill.belady2");
1209 BE_REGISTER_MODULE_CONSTRUCTOR(be_init_spillbelady2);