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 be_chordal_env_t *cenv;
35 const arch_env_t *arch;
36 const arch_register_class_t *cls;
39 /** maximum safe register pressure */
40 int registers_available;
48 typedef struct loop_edge {
53 typedef struct loop_attr {
57 /** The set of all values that are live in the loop but not used in the loop */
58 bitset_t *livethrough_unused;
61 typedef struct block_attr {
63 /** set of all values that are live in the block but not used in the block */
64 bitset_t *livethrough_unused;
67 //---------------------------------------------------------------------------
69 static int loop_edge_cmp(const void* p1, const void* p2, size_t s) {
70 loop_edge_t *e1 = (loop_edge_t*) p1;
71 loop_edge_t *e2 = (loop_edge_t*) p2;
73 return e1->block != e2->block || e1->pos != e2->pos;
76 static int loop_attr_cmp(const void *e1, const void *e2, size_t s) {
77 loop_attr_t *la1 = (loop_attr_t*) e1;
78 loop_attr_t *la2 = (loop_attr_t*) e2;
80 return la1->loop != la2->loop;
83 static int block_attr_cmp(const void *e1, const void *e2, size_t s) {
84 block_attr_t *b1 = (block_attr_t*) e1;
85 block_attr_t *b2 = (block_attr_t*) e2;
87 return b1->block != b2->block;
90 static INLINE int loop_attr_hash(const loop_attr_t *a) {
91 return HASH_PTR(a->loop);
94 static INLINE int block_attr_hash(const block_attr_t *b) {
95 return HASH_PTR(b->block);
98 static INLINE int loop_edge_hash(const loop_edge_t *e) {
99 return HASH_PTR(e->block) ^ (e->pos * 31);
102 static INLINE loop_attr_t *get_loop_attr(morgan_env_t *env, const ir_loop *loop) {
103 loop_attr_t l_attr, *res;
107 hash = loop_attr_hash(&l_attr);
108 res = set_find(env->loop_attr_set, &l_attr, sizeof(l_attr), hash);
110 // create new loop_attr if none exists yet
112 l_attr.out_edges = new_set(loop_edge_cmp, 1);
113 l_attr.in_edges = new_set(loop_edge_cmp, 1);
114 l_attr.livethrough_unused = bitset_obstack_alloc(&env->obst, get_irg_last_idx(env->irg));
115 res = set_insert(env->loop_attr_set, &l_attr, sizeof(l_attr), hash);
121 static INLINE block_attr_t *get_block_attr(morgan_env_t *env, const ir_node *block) {
122 block_attr_t b_attr, *res;
124 b_attr.block = block;
126 hash = block_attr_hash(&b_attr);
127 res = set_find(env->block_attr_set, &b_attr, sizeof(b_attr), hash);
130 b_attr.livethrough_unused = bitset_obstack_alloc(&env->obst, get_irg_last_idx(env->irg));
131 res = set_insert(env->block_attr_set, &b_attr, sizeof(b_attr), hash);
137 //---------------------------------------------------------------------------
139 static INLINE int consider_for_spilling(const arch_env_t *env, const arch_register_class_t *cls, const ir_node *node) {
140 if(!arch_irn_has_reg_class(env, node, -1, cls))
143 return !(arch_irn_get_flags(env, node) & (arch_irn_flags_ignore | arch_irn_flags_dont_spill));
147 * Determine edges going out of a loop (= edges that go to a block that is not inside
148 * the loop or one of its subloops)
150 static INLINE void construct_loop_edges(ir_node* block, void* e) {
151 morgan_env_t *env = (morgan_env_t*) e;
152 int n_cfgpreds = get_Block_n_cfgpreds(block);
154 ir_loop* loop = get_irn_loop(block);
155 loop_attr_t *loop_attr = get_loop_attr(env, loop);
156 DBG((dbg, DBG_LOOPANA, "Loop for %+F: %d (depth %d)\n", block, loop->loop_nr, loop->depth));
158 for(i = 0; i < n_cfgpreds; ++i) {
159 ir_node* cfgpred = get_Block_cfgpred(block, i);
160 ir_node* cfgpred_block = get_nodes_block(cfgpred);
161 ir_loop* cfgpred_loop = get_irn_loop(cfgpred_block);
162 loop_attr_t *outedges = get_loop_attr(env, cfgpred_loop);
164 if(cfgpred_loop == loop)
167 // is it an edge into the loop?
168 if(get_loop_depth(loop) > get_loop_depth(cfgpred_loop)) {
172 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)));
173 set_insert(loop_attr->in_edges, &edge, sizeof(edge), loop_edge_hash(&edge));
175 ir_loop *p_loop = cfgpred_loop;
176 while(get_loop_depth(p_loop) > get_loop_depth(loop)) {
177 p_loop = get_loop_outer_loop(p_loop);
183 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)));
184 set_insert(loop_attr->in_edges, &edge, sizeof(edge), loop_edge_hash(&edge));
188 // an edge out of the loop?
189 if(get_loop_depth(cfgpred_loop) >= get_loop_depth(loop)) {
193 DBG((dbg, DBG_LOOPANA, "Loop out edge from %+F (loop %d) to %+F\n", cfgpred_block, cfgpred_loop->loop_nr, block));
194 set_insert(outedges->out_edges, &edge, sizeof(edge), loop_edge_hash(&edge));
196 ir_loop *o_loop = loop;
198 // we might jump in the middle of another inner loop which is not inside
199 // our loop (happens for irreducible graphs). This would be a
200 // real out edge then.
201 while(get_loop_depth(o_loop) > get_loop_depth(cfgpred_loop)) {
202 o_loop = get_loop_outer_loop(o_loop);
205 if(cfgpred_loop != o_loop) {
209 DBG((dbg, DBG_LOOPANA, "Loop out edge from %+F (loop %d) to %+F (into jump)\n", cfgpred_block, cfgpred_loop->loop_nr, block));
210 set_insert(outedges->out_edges, &edge, sizeof(edge), loop_edge_hash(&edge));
216 static void free_loop_edges(morgan_env_t *env) {
219 for(l_attr = set_first(env->loop_attr_set); l_attr != NULL; l_attr = set_next(env->loop_attr_set)) {
220 del_set(l_attr->out_edges);
221 del_set(l_attr->in_edges);
226 * Debugging help, shows all nodes in a (node-)bitset
228 static void show_nodebitset(ir_graph* irg, const bitset_t* bitset) {
231 bitset_foreach(bitset, i) {
232 ir_node* node = get_idx_irn(irg, i);
233 DBG((dbg, DBG_LIVE, "\t%+F\n", node));
238 * Construct the livethrough unused set for a block
240 static bitset_t *construct_block_livethrough_unused(morgan_env_t* env, const ir_node* block) {
241 block_attr_t *block_attr = get_block_attr(env, block);
245 DBG((dbg, DBG_LIVE, "Processing block %d\n", get_irn_node_nr(block)));
246 // copy all live-outs into the livethrough_unused set
247 be_lv_foreach(env->cenv->lv, block, be_lv_state_in | be_lv_state_out, i) {
248 ir_node *irn = be_lv_get_irn(env->cenv->lv, block, i);
252 if(!live_is_in(li) || !live_is_out(li))
255 if(!consider_for_spilling(env->arch, env->cls, irn))
258 node_idx = get_irn_idx(irn);
259 bitset_set(block_attr->livethrough_unused, node_idx);
263 * All values that are used within the block are not unused (and therefore not
264 * livethrough_unused)
266 sched_foreach(block, node) {
269 for(i = 0, arity = get_irn_arity(node); i < arity; ++i) {
270 int idx = get_irn_idx(get_irn_n(node, i));
271 bitset_clear(block_attr->livethrough_unused, idx);
275 show_nodebitset(env->irg, block_attr->livethrough_unused);
276 return block_attr->livethrough_unused;
280 * Construct the livethrough unused set for a loop (and all its subloops+blocks)
282 static bitset_t *construct_loop_livethrough_unused(morgan_env_t *env, const ir_loop *loop) {
284 loop_attr_t* loop_attr = get_loop_attr(env, loop);
286 DBG((dbg, DBG_LIVE, "Processing Loop %d\n", loop->loop_nr));
287 assert(get_loop_n_elements(loop) > 0);
288 for(i = 0; i < get_loop_n_elements(loop); ++i) {
289 loop_element elem = get_loop_element(loop, i);
290 switch (*elem.kind) {
292 bitset_t *livethrough_block_unused;
293 assert(is_Block(elem.node));
294 livethrough_block_unused = construct_block_livethrough_unused(env, elem.node);
296 bitset_copy(loop_attr->livethrough_unused, livethrough_block_unused);
298 bitset_and(loop_attr->livethrough_unused, livethrough_block_unused);
303 bitset_t *livethrough_son_unused;
305 livethrough_son_unused = construct_loop_livethrough_unused(env, elem.son);
307 bitset_copy(loop_attr->livethrough_unused, livethrough_son_unused);
309 bitset_and(loop_attr->livethrough_unused, livethrough_son_unused);
318 DBG((dbg, DBG_LIVE, "Done with loop %d\n", loop->loop_nr));
320 // remove all unused livethroughs that are remembered for this loop from child loops and blocks
321 for(i = 0; i < get_loop_n_elements(loop); ++i) {
322 const loop_element elem = get_loop_element(loop, i);
324 if(*elem.kind == k_ir_loop) {
325 loop_attr_t *son_attr = get_loop_attr(env, elem.son);
326 bitset_andnot(son_attr->livethrough_unused, loop_attr->livethrough_unused);
328 DBG((dbg, DBG_LIVE, "Livethroughs for loop %d:\n", loop->loop_nr));
329 show_nodebitset(env->irg, son_attr->livethrough_unused);
330 } else if(*elem.kind == k_ir_node) {
331 block_attr_t *block_attr = get_block_attr(env, elem.node);
332 bitset_andnot(block_attr->livethrough_unused, loop_attr->livethrough_unused);
334 DBG((dbg, DBG_LIVE, "Livethroughs for block %+F\n", elem.node));
335 show_nodebitset(env->irg, block_attr->livethrough_unused);
341 return loop_attr->livethrough_unused;
344 /*---------------------------------------------------------------------------*/
346 static int reduce_register_pressure_in_block(morgan_env_t *env, const ir_node* block, int loop_unused_spills_possible) {
349 int max_pressure = 0;
351 int loop_unused_spills_needed;
352 block_attr_t *block_attr = get_block_attr(env, block);
353 int block_unused_spills_possible = bitset_popcnt(block_attr->livethrough_unused);
354 int unused_spills_possible = loop_unused_spills_possible + block_unused_spills_possible;
355 pset *live_nodes = pset_new_ptr_default();
357 be_liveness_end_of_block(env->cenv->lv, env->arch, env->cls, block, live_nodes);
358 pressure = pset_count(live_nodes);
360 DBG((dbg, DBG_LIVE, "Reduce pressure to %d In Block %+F:\n", env->registers_available, block));
363 * Walk over all irns in the schedule and check register pressure for each of them
365 sched_foreach_reverse(block, irn) {
366 // do we need more spills than possible with unused libethroughs?
367 int spills_needed = pressure - env->registers_available - unused_spills_possible;
368 if(spills_needed > 0) {
369 DBG((dbg, DBG_PRESSURE, "\tWARNING %d more spills needed at %+F\n", spills_needed, irn));
370 // TODO further spills needed
373 if(pressure > max_pressure) {
374 max_pressure = pressure;
377 /* Register pressure is only important until we reach the first phi (the rest of the block
378 * will only be phis.)
384 be_liveness_transfer(env->arch, env->cls, irn, live_nodes);
385 pressure = pset_count(live_nodes);
388 DBG((dbg, DBG_PRESSURE, "\tMax Pressure in %+F: %d\n", block, max_pressure));
391 * Calculate number of spills from loop_unused_spills_possible that we want to use,
392 * and spill unused livethroughs from the block if we still don't have enough registers
394 spills_needed = max_pressure - env->registers_available;
395 if(spills_needed < 0) {
396 loop_unused_spills_needed = 0;
397 } else if(spills_needed > loop_unused_spills_possible) {
399 int block_unused_spills_needed;
401 loop_unused_spills_needed = loop_unused_spills_possible;
402 block_unused_spills_needed = spills_needed - loop_unused_spills_possible;
403 if(block_unused_spills_needed > block_unused_spills_possible) {
404 block_unused_spills_needed = block_unused_spills_possible;
409 * Spill/Reload unused livethroughs from the block
411 bitset_foreach(block_attr->livethrough_unused, i) {
413 const ir_edge_t *edge;
415 if(spills >= block_unused_spills_needed)
418 to_spill = get_idx_irn(env->irg, i);
419 foreach_block_succ(block, edge) {
420 DBG((dbg, DBG_PRESSURE, "Spilling node %+F around block %+F\n", to_spill, block));
421 be_add_reload_on_edge(env->senv, to_spill, edge->src, edge->pos);
426 loop_unused_spills_needed = spills_needed;
429 del_pset(live_nodes);
431 DBG((dbg, DBG_PRESSURE, "Unused spills for Block %+F needed: %d\n", block, loop_unused_spills_needed));
432 return loop_unused_spills_needed;
436 * Reduce register pressure in a loop
438 * @param unused_spills_possible Number of spills from livethrough_unused variables possible in outer loops
439 * @return Number of spills of livethrough_unused variables needed in outer loops
441 static int reduce_register_pressure_in_loop(morgan_env_t *env, const ir_loop *loop, int outer_spills_possible) {
443 loop_attr_t* loop_attr = get_loop_attr(env, loop);
444 int spills_needed = 0;
445 int spills_possible = outer_spills_possible + bitset_popcnt(loop_attr->livethrough_unused);
446 int outer_spills_needed;
448 DBG((dbg, DBG_PRESSURE, "Reducing Pressure in loop %d\n", loop->loop_nr));
449 for(i = 0; i < get_loop_n_elements(loop); ++i) {
450 loop_element elem = get_loop_element(loop, i);
451 switch (*elem.kind) {
454 assert(is_Block(elem.node));
455 needed = reduce_register_pressure_in_block(env, elem.node, spills_possible);
456 assert(needed <= spills_possible);
457 if(needed > spills_needed)
458 spills_needed = needed;
462 int needed = reduce_register_pressure_in_loop(env, elem.son, spills_possible);
463 assert(needed <= spills_possible);
464 if(needed > spills_needed)
465 spills_needed = needed;
474 /* calculate number of spills needed in outer loop and spill
475 * unused livethrough nodes around this loop
477 if(spills_needed > outer_spills_possible) {
479 outer_spills_needed = outer_spills_possible;
480 spills_needed -= outer_spills_possible;
482 spills_to_place = spills_needed;
484 bitset_foreach(loop_attr->livethrough_unused, i) {
486 ir_node *to_spill = get_idx_irn(env->irg, i);
488 for(edge = set_first(loop_attr->out_edges); edge != NULL; edge = set_next(loop_attr->out_edges)) {
489 DBG((dbg, DBG_PRESSURE, "Spilling node %+F around loop %d\n", to_spill, loop->loop_nr));
490 be_add_reload_on_edge(env->senv, to_spill, edge->block, edge->pos);
494 if(spills_to_place <= 0) {
499 outer_spills_needed = spills_needed;
502 return outer_spills_needed;
505 void be_spill_morgan(be_chordal_env_t *chordal_env) {
508 FIRM_DBG_REGISTER(dbg, "ir.be.spillmorgan");
509 //firm_dbg_set_mask(dbg, DBG_LOOPANA | DBG_PRESSURE);
511 env.cenv = chordal_env;
512 env.arch = chordal_env->birg->main_env->arch_env;
513 env.irg = chordal_env->irg;
514 env.cls = chordal_env->cls;
515 env.senv = be_new_spill_env(chordal_env);
516 DEBUG_ONLY(be_set_spill_env_dbg_module(env.senv, dbg);)
518 obstack_init(&env.obst);
520 env.registers_available = arch_count_non_ignore_regs(env.arch, env.cls);
522 env.loop_attr_set = new_set(loop_attr_cmp, 5);
523 env.block_attr_set = new_set(block_attr_cmp, 20);
525 /*-- Part1: Analysis --*/
526 be_liveness_recompute(chordal_env->lv);
528 /* construct control flow loop tree */
529 construct_cf_backedges(chordal_env->irg);
531 /* construct loop out edges and livethrough_unused sets for loops and blocks */
532 irg_block_walk_graph(chordal_env->irg, NULL, construct_loop_edges, &env);
533 construct_loop_livethrough_unused(&env, get_irg_loop(env.irg));
535 /*-- Part2: Transformation --*/
537 /* spill unused livethrough values around loops and blocks where
538 * the pressure is too high
540 reduce_register_pressure_in_loop(&env, get_irg_loop(env.irg), 0);
542 /* Insert real spill/reload nodes and fix usages */
543 be_insert_spills_reloads(env.senv);
545 /* Verify the result */
546 if (chordal_env->opts->vrfy_option == BE_CH_VRFY_WARN) {
547 be_verify_schedule(env.irg);
548 } else if (chordal_env->opts->vrfy_option == BE_CH_VRFY_ASSERT) {
549 assert(be_verify_schedule(env.irg));
552 if (chordal_env->opts->dump_flags & BE_CH_DUMP_SPILL)
553 be_dump(env.irg, "-spillmorgan", dump_ir_block_graph_sched);
556 free_loop_edges(&env);
557 del_set(env.loop_attr_set);
558 del_set(env.block_attr_set);
560 /* fix the remaining places with too high register pressure with beladies algorithm */
562 /* we have to remove dead nodes from schedule to not confuse liveness calculation */
563 be_remove_dead_nodes_from_schedule(env.irg);
564 be_liveness_recompute(chordal_env->lv);
566 be_spill_belady_spill_env(chordal_env, env.senv);
568 be_delete_spill_env(env.senv);
569 obstack_free(&env.obst, NULL);