2 * Author: Matthias Braun
4 * Copyright: (c) Universitaet Karlsruhe
5 * License: This file is protected by GPL - GNU GENERAL PUBLIC LICENSE.
12 #include "bespillmorgan.h"
14 #include "bechordal_t.h"
22 #include "irgraph_t.h"
26 #include "bespillbelady.h"
28 #include "benodesets.h"
29 #include "bespilloptions.h"
33 #define DBG_PRESSURE 4
36 DEBUG_ONLY(static firm_dbg_module_t *dbg = NULL;)
38 typedef struct morgan_env {
39 const arch_env_t *arch;
40 const arch_register_class_t *cls;
44 /** maximum safe register pressure */
45 int registers_available;
53 typedef struct loop_edge {
58 typedef struct loop_attr {
62 /** The set of all values that are live in the loop but not used in the loop */
63 bitset_t *livethrough_unused;
66 typedef struct morgan_block_attr {
68 /** set of all values that are live in the block but not used in the block */
69 bitset_t *livethrough_unused;
72 //---------------------------------------------------------------------------
74 static int loop_edge_cmp(const void* p1, const void* p2, size_t s) {
75 loop_edge_t *e1 = (loop_edge_t*) p1;
76 loop_edge_t *e2 = (loop_edge_t*) p2;
78 return e1->block != e2->block || e1->pos != e2->pos;
81 static int loop_attr_cmp(const void *e1, const void *e2, size_t s) {
82 loop_attr_t *la1 = (loop_attr_t*) e1;
83 loop_attr_t *la2 = (loop_attr_t*) e2;
85 return la1->loop != la2->loop;
88 static int block_attr_cmp(const void *e1, const void *e2, size_t s) {
89 block_attr_t *b1 = (block_attr_t*) e1;
90 block_attr_t *b2 = (block_attr_t*) e2;
92 return b1->block != b2->block;
95 static INLINE int loop_attr_hash(const loop_attr_t *a) {
97 return a->loop->loop_nr;
99 return HASH_PTR(a->loop);
103 static INLINE int block_attr_hash(const block_attr_t *b) {
104 return nodeset_hash(b->block);
107 static INLINE int loop_edge_hash(const loop_edge_t *e) {
108 return nodeset_hash(e->block) ^ (e->pos * 31);
111 static INLINE loop_attr_t *get_loop_attr(morgan_env_t *env, const ir_loop *loop) {
112 loop_attr_t l_attr, *res;
116 hash = loop_attr_hash(&l_attr);
117 res = set_find(env->loop_attr_set, &l_attr, sizeof(l_attr), hash);
119 // create new loop_attr if none exists yet
121 l_attr.out_edges = new_set(loop_edge_cmp, 1);
122 l_attr.in_edges = new_set(loop_edge_cmp, 1);
123 l_attr.livethrough_unused = bitset_obstack_alloc(&env->obst, get_irg_last_idx(env->irg));
124 res = set_insert(env->loop_attr_set, &l_attr, sizeof(l_attr), hash);
130 static INLINE block_attr_t *get_block_attr(morgan_env_t *env, const ir_node *block) {
131 block_attr_t b_attr, *res;
133 b_attr.block = block;
135 hash = block_attr_hash(&b_attr);
136 res = set_find(env->block_attr_set, &b_attr, sizeof(b_attr), hash);
139 b_attr.livethrough_unused = NULL;
140 res = set_insert(env->block_attr_set, &b_attr, sizeof(b_attr), hash);
146 //---------------------------------------------------------------------------
148 static INLINE int consider_for_spilling(const arch_env_t *env, const arch_register_class_t *cls, const ir_node *node) {
149 if(!arch_irn_has_reg_class(env, node, -1, cls))
152 return !(arch_irn_get_flags(env, node) & (arch_irn_flags_ignore | arch_irn_flags_dont_spill));
156 * Determine edges going out of a loop (= edges that go to a block that is not
157 * inside the loop or one of its subloops)
159 static INLINE void construct_loop_edges(ir_node *block, void *data) {
160 morgan_env_t *env = data;
161 int n_cfgpreds = get_Block_n_cfgpreds(block);
163 ir_loop* loop = get_irn_loop(block);
164 DBG((dbg, DBG_LOOPANA, "Loop for %+F: %d (depth %d)\n", block, loop->loop_nr, loop->depth));
166 for(i = 0; i < n_cfgpreds; ++i) {
169 ir_node* cfgpred = get_Block_cfgpred(block, i);
170 ir_node* cfgpred_block = get_nodes_block(cfgpred);
171 ir_loop* cfgpred_loop = get_irn_loop(cfgpred_block);
173 if(cfgpred_loop == loop)
176 assert(get_loop_depth(cfgpred_loop) != get_loop_depth(loop));
180 hash = loop_edge_hash(&edge);
182 // edge out of a loop?
183 if(get_loop_depth(cfgpred_loop) > get_loop_depth(loop)) {
186 DBG((dbg, DBG_LOOPANA, "Loop out edge from %+F (loop %d) to %+F (loop %d)\n", block, get_loop_loop_nr(loop),
187 cfgpred_block, get_loop_loop_nr(cfgpred_loop)));
189 /* this might be a jump out of multiple loops, so add this to all
190 * needed outedge sets */
193 loop_attr_t *l_attr = get_loop_attr(env, l);
194 set_insert(l_attr->out_edges, &edge, sizeof(edge), hash);
196 l = get_loop_outer_loop(l);
203 DBG((dbg, DBG_LOOPANA, "Loop in edge from %+F (loop %d) to %+F (loop %d)\n", block, get_loop_loop_nr(loop),
204 cfgpred_block, get_loop_loop_nr(cfgpred_loop)));
208 loop_attr_t *l_attr = get_loop_attr(env, l);
209 set_insert(l_attr->in_edges, &edge, sizeof(edge), hash);
211 l = get_loop_outer_loop(l);
212 } while(l != cfgpred_loop);
217 static void free_loop_edges(morgan_env_t *env) {
220 for(l_attr = set_first(env->loop_attr_set); l_attr != NULL; l_attr = set_next(env->loop_attr_set)) {
221 del_set(l_attr->out_edges);
222 del_set(l_attr->in_edges);
228 * Debugging help, shows all nodes in a (node-)bitset
230 static void show_nodebitset(ir_graph* irg, const bitset_t* bitset) {
233 bitset_foreach(bitset, i) {
234 ir_node* node = get_idx_irn(irg, i);
235 ir_fprintf(stderr, " %+F", node);
237 fprintf(stderr, "\n");
241 static INLINE void init_livethrough_unuseds(block_attr_t *attr, morgan_env_t *env) {
242 const ir_node *block;
244 const be_lv_t *lv = env->lv;
246 if(attr->livethrough_unused != NULL)
251 attr->livethrough_unused = bitset_obstack_alloc(&env->obst, get_irg_last_idx(env->irg));
253 // copy all live-outs into the livethrough_unused set
254 be_lv_foreach(lv, block, be_lv_state_in | be_lv_state_out, i) {
255 ir_node *irn = be_lv_get_irn(lv, block, i);
258 if(!consider_for_spilling(env->arch, env->cls, irn))
261 node_idx = get_irn_idx(irn);
262 bitset_set(attr->livethrough_unused, node_idx);
267 * Construct the livethrough unused set for a block
269 static void construct_block_livethrough_unused(ir_node *block, void *data) {
270 morgan_env_t* env = data;
271 block_attr_t *block_attr = get_block_attr(env, block);
274 block_attr_t **pred_attrs = NULL;
277 init_livethrough_unuseds(block_attr, env);
279 DBG((dbg, DBG_LIVE, "Processing block %d\n", get_irn_node_nr(block)));
281 n_cfgpreds = get_Block_n_cfgpreds(block);
283 pred_attrs = alloca(sizeof(pred_attrs[0]) * n_cfgpreds);
284 for(i = 0; i < n_cfgpreds; ++i) {
285 ir_node *pred_block = get_Block_cfgpred_block(block, i);
286 pred_attrs[i] = get_block_attr(env, pred_block);
287 init_livethrough_unuseds(pred_attrs[i], env);
292 * All values that are used within the block are not unused (and therefore not
293 * livethrough_unused)
295 sched_foreach(block, node) {
298 // phis are really uses in the pred block
301 for(j = 0; j < n_cfgpreds; ++j) {
302 ir_node *used_value = get_Phi_pred(node, j);
303 int idx = get_irn_idx(used_value);
304 block_attr_t *pred_attr = pred_attrs[j];
306 bitset_clear(pred_attr->livethrough_unused, idx);
309 // mark all used values as used
310 for(i = 0, arity = get_irn_arity(node); i < arity; ++i) {
311 int idx = get_irn_idx(get_irn_n(node, i));
312 bitset_clear(block_attr->livethrough_unused, idx);
319 * Construct the livethrough unused set for a loop (and all its subloops+blocks)
321 static bitset_t *construct_loop_livethrough_unused(morgan_env_t *env, const ir_loop *loop) {
323 loop_attr_t* loop_attr = get_loop_attr(env, loop);
325 DBG((dbg, DBG_LIVE, "Processing Loop %d\n", loop->loop_nr));
326 assert(get_loop_n_elements(loop) > 0);
327 for(i = 0; i < get_loop_n_elements(loop); ++i) {
328 loop_element elem = get_loop_element(loop, i);
329 switch (*elem.kind) {
331 ir_node *block = elem.node;
332 block_attr_t *block_attr = get_block_attr(env, block);
333 bitset_t *livethrough_block_unused = block_attr->livethrough_unused;
335 assert(is_Block(elem.node));
336 assert(livethrough_block_unused != NULL);
339 bitset_copy(loop_attr->livethrough_unused, livethrough_block_unused);
341 bitset_and(loop_attr->livethrough_unused, livethrough_block_unused);
346 bitset_t *livethrough_son_unused;
348 livethrough_son_unused = construct_loop_livethrough_unused(env, elem.son);
350 bitset_copy(loop_attr->livethrough_unused, livethrough_son_unused);
352 bitset_and(loop_attr->livethrough_unused, livethrough_son_unused);
361 DBG((dbg, DBG_LIVE, "Done with loop %d\n", loop->loop_nr));
363 // remove all unused livethroughs that are remembered for this loop from child loops and blocks
364 for(i = 0; i < get_loop_n_elements(loop); ++i) {
365 const loop_element elem = get_loop_element(loop, i);
367 if(*elem.kind == k_ir_loop) {
368 loop_attr_t *son_attr = get_loop_attr(env, elem.son);
369 bitset_andnot(son_attr->livethrough_unused, loop_attr->livethrough_unused);
371 DBG((dbg, DBG_LIVE, "Livethroughs for loop %d:\n", loop->loop_nr));
372 } else if(*elem.kind == k_ir_node) {
373 block_attr_t *block_attr = get_block_attr(env, elem.node);
374 bitset_andnot(block_attr->livethrough_unused, loop_attr->livethrough_unused);
376 DBG((dbg, DBG_LIVE, "Livethroughs for block %+F\n", elem.node));
382 return loop_attr->livethrough_unused;
385 /*---------------------------------------------------------------------------*/
387 typedef struct _spillcandidate_t {
392 static int compare_spillcandidates(const void *d1, const void *d2) {
393 const spillcandidate_t *cand1 = d1;
394 const spillcandidate_t *cand2 = d2;
396 return cand1->cost - cand2->cost;
399 static void spill_values(morgan_env_t *env, const loop_attr_t *loop_attr, int spills) {
400 const bitset_t *cand_bitset = loop_attr->livethrough_unused;
401 int candidatecount = bitset_popcnt(cand_bitset);
402 spillcandidate_t *candidates;
406 assert(spills <= candidatecount);
408 candidates = alloca(sizeof(candidates[0]) * candidatecount);
410 DBG((dbg, DBG_CHOOSE, "Candidates for loop %d\n", get_loop_loop_nr(loop_attr->loop)));
411 // build candidiatelist
413 bitset_foreach(cand_bitset, i) {
414 ir_node *node = get_idx_irn(env->irg, i);
415 candidates[c].node = node;
416 candidates[c].cost = 0;
418 for(edge = set_first(loop_attr->out_edges); edge != NULL; edge = set_next(loop_attr->out_edges)) {
419 candidates[c].cost += be_get_reload_costs_on_edge(env->senv, node, edge->block, edge->pos);
421 DBG((dbg, DBG_CHOOSE, "%+F has costs %d\n", node, candidates[c].cost));
425 assert(c == candidatecount);
428 qsort(candidates, candidatecount, sizeof(candidates[0]), compare_spillcandidates);
431 for(i = 0; i < spills; ++i) {
432 ir_node *to_spill = candidates[i].node;
433 DBG((dbg, DBG_CHOOSE, "Spilling %+F ", to_spill));
435 for(edge = set_first(loop_attr->out_edges); edge != NULL; edge = set_next(loop_attr->out_edges)) {
436 be_add_reload_on_edge(env->senv, to_spill, edge->block, edge->pos, env->cls, 1);
441 static int reduce_register_pressure_in_block(morgan_env_t *env, const ir_node* block, int loop_unused_spills_possible) {
444 int loop_unused_spills_needed;
445 pset *live_nodes = pset_new_ptr_default();
446 const be_lv_t *lv = env->lv;
448 be_liveness_end_of_block(lv, env->arch, env->cls, block, live_nodes);
449 max_pressure = pset_count(live_nodes);
451 DBG((dbg, DBG_LIVE, "Reduce pressure to %d In Block %+F:\n", env->registers_available, block));
454 * Determine register pressure in block
456 sched_foreach_reverse(block, node) {
462 be_liveness_transfer(env->arch, env->cls, node, live_nodes);
463 pressure = pset_count(live_nodes);
464 if(pressure > max_pressure)
465 max_pressure = pressure;
467 del_pset(live_nodes);
469 loop_unused_spills_needed = max_pressure - env->registers_available;
471 if(loop_unused_spills_needed < 0) {
472 loop_unused_spills_needed = 0;
473 } else if(loop_unused_spills_needed > loop_unused_spills_possible) {
474 loop_unused_spills_needed = loop_unused_spills_possible;
477 DBG((dbg, DBG_PRESSURE, "Block %+F: max-pressure %d spills possible: %d spills used: %d\n",
478 block, max_pressure, loop_unused_spills_possible, loop_unused_spills_needed));
479 return loop_unused_spills_needed;
483 * Reduce register pressure in a loop
485 * @param unused_spills_possible Number of spills from livethrough_unused variables possible in outer loops
486 * @return Number of spills of livethrough_unused variables needed in outer loops
488 static int reduce_register_pressure_in_loop(morgan_env_t *env, const ir_loop *loop, int outer_spills_possible) {
490 loop_attr_t* loop_attr = get_loop_attr(env, loop);
491 int spills_needed = 0;
492 int spills_possible = outer_spills_possible + bitset_popcnt(loop_attr->livethrough_unused);
493 int outer_spills_needed;
495 DBG((dbg, DBG_PRESSURE, "Reducing Pressure in loop %d\n", loop->loop_nr));
496 for(i = 0; i < get_loop_n_elements(loop); ++i) {
497 loop_element elem = get_loop_element(loop, i);
498 switch (*elem.kind) {
501 assert(is_Block(elem.node));
502 needed = reduce_register_pressure_in_block(env, elem.node, spills_possible);
504 assert(needed <= spills_possible);
505 if(needed > spills_needed)
506 spills_needed = needed;
510 int needed = reduce_register_pressure_in_loop(env, elem.son, spills_possible);
512 assert(needed <= spills_possible);
513 if(needed > spills_needed)
514 spills_needed = needed;
523 /* calculate number of spills needed in outer loop and spill
524 * unused livethrough nodes around this loop */
525 if(spills_needed > outer_spills_possible) {
527 outer_spills_needed = outer_spills_possible;
528 spills_needed -= outer_spills_possible;
530 spills_to_place = spills_needed;
532 DBG((dbg, DBG_SPILLS, "%d values unused in loop %d, spilling %d\n",
533 spills_possible - outer_spills_possible, loop->loop_nr, spills_to_place));
535 spill_values(env, loop_attr, spills_to_place);
537 outer_spills_needed = spills_needed;
540 return outer_spills_needed;
543 void be_spill_morgan(be_irg_t *birg, const arch_register_class_t *cls) {
544 ir_graph *irg = be_get_birg_irg(birg);
547 FIRM_DBG_REGISTER(dbg, "ir.be.spillmorgan");
548 //firm_dbg_set_mask(dbg, DBG_SPILLS | DBG_LOOPANA);
550 be_assure_liveness(birg);
552 env.arch = birg->main_env->arch_env;
555 env.lv = be_get_birg_liveness(birg);
556 env.senv = be_new_spill_env(birg);
557 DEBUG_ONLY(be_set_spill_env_dbg_module(env.senv, dbg);)
559 obstack_init(&env.obst);
561 env.registers_available = env.cls->n_regs - be_put_ignore_regs(birg, env.cls, NULL);
563 env.loop_attr_set = new_set(loop_attr_cmp, 5);
564 env.block_attr_set = new_set(block_attr_cmp, 20);
566 /*-- Part1: Analysis --*/
568 /* construct control flow loop tree */
569 if(! (get_irg_loopinfo_state(irg) & loopinfo_cf_consistent)) {
570 construct_cf_backedges(irg);
573 /* construct loop out edges and livethrough_unused sets for loops and blocks */
574 irg_block_walk_graph(irg, construct_block_livethrough_unused, construct_loop_edges, &env);
575 construct_loop_livethrough_unused(&env, get_irg_loop(irg));
577 /*-- Part2: Transformation --*/
579 /* spill unused livethrough values around loops and blocks where
580 * the pressure is too high
582 reduce_register_pressure_in_loop(&env, get_irg_loop(irg), 0);
584 /* Insert real spill/reload nodes and fix usages */
585 be_insert_spills_reloads(env.senv);
587 /* Verify the result */
588 if(birg->main_env->options->vrfy_option == BE_VRFY_WARN) {
589 be_verify_schedule(irg);
590 } else if (birg->main_env->options->vrfy_option == BE_VRFY_ASSERT) {
591 assert(be_verify_schedule(irg));
595 free_loop_edges(&env);
596 del_set(env.loop_attr_set);
597 del_set(env.block_attr_set);
599 /* fix the remaining places with too high register pressure with beladies algorithm */
600 be_spill_belady_spill_env(birg, cls, env.senv);
602 be_delete_spill_env(env.senv);
603 obstack_free(&env.obst, NULL);
606 void be_init_spillmorgan(void)
608 static be_spiller_t morgan_spiller = {
612 be_register_spiller("morgan", &morgan_spiller);
615 BE_REGISTER_MODULE_CONSTRUCTOR(be_init_spillmorgan);