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"
21 #include "irgraph_t.h"
25 #include "bespillbelady.h"
30 #define DBG_PRESSURE 4
31 DEBUG_ONLY(static firm_dbg_module_t *dbg = NULL;)
33 typedef struct morgan_env {
34 const arch_env_t *arch;
35 const arch_register_class_t *cls;
38 /** maximum safe register pressure */
39 int registers_available;
47 typedef struct loop_edge {
52 typedef struct loop_attr {
56 /** The set of all values that are live in the loop but not used in the loop */
57 bitset_t *livethrough_unused;
60 typedef struct block_attr {
62 /** set of all values that are live in the block but not used in the block */
63 bitset_t *livethrough_unused;
66 //---------------------------------------------------------------------------
68 static int loop_edge_cmp(const void* p1, const void* p2, size_t s) {
69 loop_edge_t *e1 = (loop_edge_t*) p1;
70 loop_edge_t *e2 = (loop_edge_t*) p2;
72 return e1->block != e2->block || e1->pos != e2->pos;
75 static int loop_attr_cmp(const void *e1, const void *e2, size_t s) {
76 loop_attr_t *la1 = (loop_attr_t*) e1;
77 loop_attr_t *la2 = (loop_attr_t*) e2;
79 return la1->loop != la2->loop;
82 static int block_attr_cmp(const void *e1, const void *e2, size_t s) {
83 block_attr_t *b1 = (block_attr_t*) e1;
84 block_attr_t *b2 = (block_attr_t*) e2;
86 return b1->block != b2->block;
89 static INLINE int loop_attr_hash(const loop_attr_t *a) {
90 return HASH_PTR(a->loop);
93 static INLINE int block_attr_hash(const block_attr_t *b) {
94 return HASH_PTR(b->block);
97 static INLINE int loop_edge_hash(const loop_edge_t *e) {
98 return HASH_PTR(e->block) ^ (e->pos * 31);
101 static INLINE loop_attr_t *get_loop_attr(morgan_env_t *env, const ir_loop *loop) {
102 loop_attr_t l_attr, *res;
106 hash = loop_attr_hash(&l_attr);
107 res = set_find(env->loop_attr_set, &l_attr, sizeof(l_attr), hash);
109 // create new loop_attr if none exists yet
111 l_attr.out_edges = new_set(loop_edge_cmp, 1);
112 l_attr.in_edges = new_set(loop_edge_cmp, 1);
113 l_attr.livethrough_unused = bitset_obstack_alloc(&env->obst, get_irg_last_idx(env->irg));
114 res = set_insert(env->loop_attr_set, &l_attr, sizeof(l_attr), hash);
120 static INLINE block_attr_t *get_block_attr(morgan_env_t *env, const ir_node *block) {
121 block_attr_t b_attr, *res;
123 b_attr.block = block;
125 hash = block_attr_hash(&b_attr);
126 res = set_find(env->block_attr_set, &b_attr, sizeof(b_attr), hash);
129 b_attr.livethrough_unused = bitset_obstack_alloc(&env->obst, get_irg_last_idx(env->irg));
130 res = set_insert(env->block_attr_set, &b_attr, sizeof(b_attr), hash);
136 //---------------------------------------------------------------------------
138 static INLINE int consider_for_spilling(const arch_env_t *env, const arch_register_class_t *cls, const ir_node *node) {
139 if(!arch_irn_has_reg_class(env, node, -1, cls))
142 return !(arch_irn_get_flags(env, node) & (arch_irn_flags_ignore | arch_irn_flags_dont_spill));
146 * Determine edges going out of a loop (= edges that go to a block that is not inside
147 * the loop or one of its subloops)
149 static INLINE void construct_loop_edges(ir_node* block, void* e) {
150 morgan_env_t *env = (morgan_env_t*) e;
151 int n_cfgpreds = get_Block_n_cfgpreds(block);
153 ir_loop* loop = get_irn_loop(block);
154 loop_attr_t *loop_attr = get_loop_attr(env, loop);
155 DBG((dbg, DBG_LOOPANA, "Loop for %+F: %d (depth %d)\n", block, loop->loop_nr, loop->depth));
157 for(i = 0; i < n_cfgpreds; ++i) {
158 ir_node* cfgpred = get_Block_cfgpred(block, i);
159 ir_node* cfgpred_block = get_nodes_block(cfgpred);
160 ir_loop* cfgpred_loop = get_irn_loop(cfgpred_block);
161 loop_attr_t *outedges = get_loop_attr(env, cfgpred_loop);
163 if(cfgpred_loop == loop)
166 // is it an edge into the loop?
167 if(get_loop_depth(loop) > get_loop_depth(cfgpred_loop)) {
171 DBG((dbg, DBG_LOOPANA, "Loop in edge from %+F (loop %d) to %+F (loop %d)\n", cfgpred_block, get_loop_loop_nr(cfgpred_loop), block, get_loop_loop_nr(loop)));
172 set_insert(loop_attr->in_edges, &edge, sizeof(edge), loop_edge_hash(&edge));
174 ir_loop *p_loop = cfgpred_loop;
175 while(get_loop_depth(p_loop) > get_loop_depth(loop)) {
176 p_loop = get_loop_outer_loop(p_loop);
182 DBG((dbg, DBG_LOOPANA, "Loop in edge from %+F (loop %d) to %+F (loop %d)\n", cfgpred_block, get_loop_loop_nr(cfgpred_loop), block, get_loop_loop_nr(loop)));
183 set_insert(loop_attr->in_edges, &edge, sizeof(edge), loop_edge_hash(&edge));
187 // an edge out of the loop?
188 if(get_loop_depth(cfgpred_loop) >= get_loop_depth(loop)) {
192 DBG((dbg, DBG_LOOPANA, "Loop out edge from %+F (loop %d) to %+F\n", cfgpred_block, cfgpred_loop->loop_nr, block));
193 set_insert(outedges->out_edges, &edge, sizeof(edge), loop_edge_hash(&edge));
195 ir_loop *o_loop = loop;
197 // we might jump in the middle of another inner loop which is not inside
198 // our loop (happens for irreducible graphs). This would be a
199 // real out edge then.
200 while(get_loop_depth(o_loop) > get_loop_depth(cfgpred_loop)) {
201 o_loop = get_loop_outer_loop(o_loop);
204 if(cfgpred_loop != o_loop) {
208 DBG((dbg, DBG_LOOPANA, "Loop out edge from %+F (loop %d) to %+F (into jump)\n", cfgpred_block, cfgpred_loop->loop_nr, block));
209 set_insert(outedges->out_edges, &edge, sizeof(edge), loop_edge_hash(&edge));
215 static void free_loop_edges(morgan_env_t *env) {
218 for(l_attr = set_first(env->loop_attr_set); l_attr != NULL; l_attr = set_next(env->loop_attr_set)) {
219 del_set(l_attr->out_edges);
220 del_set(l_attr->in_edges);
225 * Debugging help, shows all nodes in a (node-)bitset
227 static void show_nodebitset(ir_graph* irg, const bitset_t* bitset) {
230 bitset_foreach(bitset, i) {
231 ir_node* node = get_idx_irn(irg, i);
232 DBG((dbg, DBG_LIVE, "\t%+F\n", node));
237 * Construct the livethrough unused set for a block
239 static bitset_t *construct_block_livethrough_unused(morgan_env_t* env, const ir_node* block) {
240 block_attr_t *block_attr = get_block_attr(env, block);
244 DBG((dbg, DBG_LIVE, "Processing block %d\n", get_irn_node_nr(block)));
245 // copy all live-outs into the livethrough_unused set
246 live_foreach(block, li) {
249 if(!live_is_in(li) || !live_is_out(li))
251 if(!consider_for_spilling(env->arch, env->cls, li->irn))
254 node_idx = get_irn_idx(li->irn);
255 bitset_set(block_attr->livethrough_unused, node_idx);
259 * All values that are used within the block are not unused (and therefore not
260 * livethrough_unused)
262 sched_foreach(block, node) {
265 for(i = 0, arity = get_irn_arity(node); i < arity; ++i) {
266 int idx = get_irn_idx(get_irn_n(node, i));
267 bitset_clear(block_attr->livethrough_unused, idx);
271 show_nodebitset(env->irg, block_attr->livethrough_unused);
272 return block_attr->livethrough_unused;
276 * Construct the livethrough unused set for a loop (and all its subloops+blocks)
278 static bitset_t *construct_loop_livethrough_unused(morgan_env_t *env, const ir_loop *loop) {
280 loop_attr_t* loop_attr = get_loop_attr(env, loop);
282 DBG((dbg, DBG_LIVE, "Processing Loop %d\n", loop->loop_nr));
283 assert(get_loop_n_elements(loop) > 0);
284 for(i = 0; i < get_loop_n_elements(loop); ++i) {
285 loop_element elem = get_loop_element(loop, i);
286 switch (*elem.kind) {
288 bitset_t *livethrough_block_unused;
289 assert(is_Block(elem.node));
290 livethrough_block_unused = construct_block_livethrough_unused(env, elem.node);
292 bitset_copy(loop_attr->livethrough_unused, livethrough_block_unused);
294 bitset_and(loop_attr->livethrough_unused, livethrough_block_unused);
299 bitset_t *livethrough_son_unused;
301 livethrough_son_unused = construct_loop_livethrough_unused(env, elem.son);
303 bitset_copy(loop_attr->livethrough_unused, livethrough_son_unused);
305 bitset_and(loop_attr->livethrough_unused, livethrough_son_unused);
314 DBG((dbg, DBG_LIVE, "Done with loop %d\n", loop->loop_nr));
316 // remove all unused livethroughs that are remembered for this loop from child loops and blocks
317 for(i = 0; i < get_loop_n_elements(loop); ++i) {
318 const loop_element elem = get_loop_element(loop, i);
320 if(*elem.kind == k_ir_loop) {
321 loop_attr_t *son_attr = get_loop_attr(env, elem.son);
322 bitset_andnot(son_attr->livethrough_unused, loop_attr->livethrough_unused);
324 DBG((dbg, DBG_LIVE, "Livethroughs for loop %d:\n", loop->loop_nr));
325 show_nodebitset(env->irg, son_attr->livethrough_unused);
326 } else if(*elem.kind == k_ir_node) {
327 block_attr_t *block_attr = get_block_attr(env, elem.node);
328 bitset_andnot(block_attr->livethrough_unused, loop_attr->livethrough_unused);
330 DBG((dbg, DBG_LIVE, "Livethroughs for block %+F\n", elem.node));
331 show_nodebitset(env->irg, block_attr->livethrough_unused);
337 return loop_attr->livethrough_unused;
340 /*---------------------------------------------------------------------------*/
342 static int reduce_register_pressure_in_block(morgan_env_t *env, const ir_node* block, int loop_unused_spills_possible) {
345 int max_pressure = 0;
347 int loop_unused_spills_needed;
348 block_attr_t *block_attr = get_block_attr(env, block);
349 int block_unused_spills_possible = bitset_popcnt(block_attr->livethrough_unused);
350 int unused_spills_possible = loop_unused_spills_possible + block_unused_spills_possible;
351 pset *live_nodes = pset_new_ptr_default();
353 be_liveness_end_of_block(env->arch, env->cls, block, live_nodes);
354 pressure = pset_count(live_nodes);
356 DBG((dbg, DBG_LIVE, "Reduce pressure to %d In Block %+F:\n", env->registers_available, block));
359 * Walk over all irns in the schedule and check register pressure for each of them
361 sched_foreach_reverse(block, irn) {
362 // do we need more spills than possible with unused libethroughs?
363 int spills_needed = pressure - env->registers_available - unused_spills_possible;
364 if(spills_needed > 0) {
365 DBG((dbg, DBG_PRESSURE, "\tWARNING %d more spills needed at %+F\n", spills_needed, irn));
366 // TODO further spills needed
369 if(pressure > max_pressure) {
370 max_pressure = pressure;
373 /* Register pressure is only important until we reach the first phi (the rest of the block
374 * will only be phis.)
380 be_liveness_transfer(env->arch, env->cls, irn, live_nodes);
381 pressure = pset_count(live_nodes);
384 DBG((dbg, DBG_PRESSURE, "\tMax Pressure in %+F: %d\n", block, max_pressure));
387 * Calculate number of spills from loop_unused_spills_possible that we want to use,
388 * and spill unused livethroughs from the block if we still don't have enough registers
390 spills_needed = max_pressure - env->registers_available;
391 if(spills_needed < 0) {
392 loop_unused_spills_needed = 0;
393 } else if(spills_needed > loop_unused_spills_possible) {
395 int block_unused_spills_needed;
397 loop_unused_spills_needed = loop_unused_spills_possible;
398 block_unused_spills_needed = spills_needed - loop_unused_spills_possible;
399 if(block_unused_spills_needed > block_unused_spills_possible) {
400 block_unused_spills_needed = block_unused_spills_possible;
405 * Spill/Reload unused livethroughs from the block
407 bitset_foreach(block_attr->livethrough_unused, i) {
409 const ir_edge_t *edge;
411 if(spills >= block_unused_spills_needed)
414 to_spill = get_idx_irn(env->irg, i);
415 foreach_block_succ(block, edge) {
416 DBG((dbg, DBG_PRESSURE, "Spilling node %+F around block %+F\n", to_spill, block));
417 be_add_reload_on_edge(env->senv, to_spill, edge->src, edge->pos);
422 loop_unused_spills_needed = spills_needed;
425 del_pset(live_nodes);
427 DBG((dbg, DBG_PRESSURE, "Unused spills for Block %+F needed: %d\n", block, loop_unused_spills_needed));
428 return loop_unused_spills_needed;
432 * Reduce register pressure in a loop
434 * @param unused_spills_possible Number of spills from livethrough_unused variables possible in outer loops
435 * @return Number of spills of livethrough_unused variables needed in outer loops
437 static int reduce_register_pressure_in_loop(morgan_env_t *env, const ir_loop *loop, int outer_spills_possible) {
439 loop_attr_t* loop_attr = get_loop_attr(env, loop);
440 int spills_needed = 0;
441 int spills_possible = outer_spills_possible + bitset_popcnt(loop_attr->livethrough_unused);
442 int outer_spills_needed;
444 DBG((dbg, DBG_PRESSURE, "Reducing Pressure in loop %d\n", loop->loop_nr));
445 for(i = 0; i < get_loop_n_elements(loop); ++i) {
446 loop_element elem = get_loop_element(loop, i);
447 switch (*elem.kind) {
450 assert(is_Block(elem.node));
451 needed = reduce_register_pressure_in_block(env, elem.node, spills_possible);
452 assert(needed <= spills_possible);
453 if(needed > spills_needed)
454 spills_needed = needed;
458 int needed = reduce_register_pressure_in_loop(env, elem.son, spills_possible);
459 assert(needed <= spills_possible);
460 if(needed > spills_needed)
461 spills_needed = needed;
470 /* calculate number of spills needed in outer loop and spill
471 * unused livethrough nodes around this loop
473 if(spills_needed > outer_spills_possible) {
475 outer_spills_needed = outer_spills_possible;
476 spills_needed -= outer_spills_possible;
478 spills_to_place = spills_needed;
480 bitset_foreach(loop_attr->livethrough_unused, i) {
482 ir_node *to_spill = get_idx_irn(env->irg, i);
484 for(edge = set_first(loop_attr->out_edges); edge != NULL; edge = set_next(loop_attr->out_edges)) {
485 DBG((dbg, DBG_PRESSURE, "Spilling node %+F around loop %d\n", to_spill, loop->loop_nr));
486 be_add_reload_on_edge(env->senv, to_spill, edge->block, edge->pos);
490 if(spills_to_place <= 0) {
495 outer_spills_needed = spills_needed;
498 return outer_spills_needed;
501 void be_spill_morgan(const be_chordal_env_t *chordal_env) {
504 FIRM_DBG_REGISTER(dbg, "ir.be.spillmorgan");
505 //firm_dbg_set_mask(dbg, DBG_LOOPANA | DBG_PRESSURE);
507 env.arch = chordal_env->birg->main_env->arch_env;
508 env.irg = chordal_env->irg;
509 env.cls = chordal_env->cls;
510 env.senv = be_new_spill_env(chordal_env);
511 DEBUG_ONLY(be_set_spill_env_dbg_module(env.senv, dbg);)
513 obstack_init(&env.obst);
515 env.registers_available = arch_count_non_ignore_regs(env.arch, env.cls);
517 env.loop_attr_set = new_set(loop_attr_cmp, 5);
518 env.block_attr_set = new_set(block_attr_cmp, 20);
520 /*-- Part1: Analysis --*/
521 be_liveness(env.irg);
523 /* construct control flow loop tree */
524 construct_cf_backedges(chordal_env->irg);
526 /* construct loop out edges and livethrough_unused sets for loops and blocks */
527 irg_block_walk_graph(chordal_env->irg, NULL, construct_loop_edges, &env);
528 construct_loop_livethrough_unused(&env, get_irg_loop(env.irg));
530 /*-- Part2: Transformation --*/
532 /* spill unused livethrough values around loops and blocks where
533 * the pressure is too high
535 reduce_register_pressure_in_loop(&env, get_irg_loop(env.irg), 0);
537 /* Place copies for spilled phis */
538 be_place_copies(env.senv);
539 /* Insert real spill/reload nodes and fix usages */
540 be_insert_spills_reloads(env.senv);
542 /* Verify the result */
543 if (chordal_env->opts->vrfy_option == BE_CH_VRFY_WARN) {
544 be_verify_schedule(env.irg);
545 } else if (chordal_env->opts->vrfy_option == BE_CH_VRFY_ASSERT) {
546 assert(be_verify_schedule(env.irg));
549 if (chordal_env->opts->dump_flags & BE_CH_DUMP_SPILL)
550 be_dump(env.irg, "-spillmorgan", dump_ir_block_graph_sched);
553 free_loop_edges(&env);
554 del_set(env.loop_attr_set);
555 del_set(env.block_attr_set);
557 /* fix the remaining places with too high register pressure with beladies algorithm */
559 /* we have to remove dead nodes from schedule to not confuse liveness calculation */
560 be_remove_dead_nodes_from_schedule(env.irg);
561 be_liveness(env.irg);
563 be_spill_belady_spill_env(chordal_env, env.senv);
565 be_delete_spill_env(env.senv);
566 obstack_free(&env.obst, NULL);