2 * Author: Matthias Braun
4 * Copyright: (c) Universitaet Karlsruhe
5 * License: This file protected by GPL - GNU GENERAL PUBLIC LICENSE.
12 #include "bespillmorgan.h"
14 #include "bechordal.h"
15 #include "bechordal_t.h"
25 #include "irgraph_t.h"
27 #include "irphase_t.h"
30 #include "bespillbelady.h"
34 #define DBG_PRESSURE 2
35 DEBUG_ONLY(static firm_dbg_module_t *dbg = NULL;)
37 typedef struct _morgan_env_t {
38 const arch_env_t *arch;
39 const arch_register_class_t *cls;
42 // maximum safe register pressure
43 int registers_available;
51 typedef struct _loop_out_edge_t {
56 typedef struct _loop_attr_t {
59 /// The set of all values that live through the loop and are not used
60 bitset_t *livethrough_unused;
63 typedef struct _block_attr_t {
65 bitset_t *livethrough_unused;
68 //---------------------------------------------------------------------------
70 int loop_out_edge_cmp(const void* p1, const void* p2, size_t s) {
71 loop_out_edge_t *e1 = (loop_out_edge_t*) p1;
72 loop_out_edge_t *e2 = (loop_out_edge_t*) p2;
74 return e1->block != e2->block || e1->pos != e2->pos;
77 int loop_attr_cmp(const void *e1, const void *e2, size_t s) {
78 loop_attr_t *la1 = (loop_attr_t*) e1;
79 loop_attr_t *la2 = (loop_attr_t*) e2;
81 return la1->loop != la2->loop;
84 int block_attr_cmp(const void *e1, const void *e2, size_t s) {
85 block_attr_t *b1 = (block_attr_t*) e1;
86 block_attr_t *b2 = (block_attr_t*) e2;
88 return b1->block != b2->block;
91 static INLINE int loop_attr_hash(const loop_attr_t *a) {
92 return HASH_PTR(a->loop);
95 static INLINE int block_attr_hash(const block_attr_t *b) {
96 return HASH_PTR(b->block);
99 static INLINE int loop_out_edge_hash(const loop_out_edge_t *e) {
100 return HASH_PTR(e->block) ^ (e->pos * 31);
103 static INLINE loop_attr_t *get_loop_attr(morgan_env_t *env, ir_loop *loop) {
104 loop_attr_t l_attr, *res;
108 hash = loop_attr_hash(&l_attr);
109 res = set_find(env->loop_attr_set, &l_attr, sizeof(l_attr), hash);
111 // create new loop_attr if none exists yet
113 l_attr.out_edges = new_set(loop_out_edge_cmp, 1);
114 l_attr.livethrough_unused = bitset_obstack_alloc(&env->phase.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, 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->phase.obst, get_irg_last_idx(env->irg));
131 res = set_insert(env->block_attr_set, &b_attr, sizeof(b_attr), hash);
137 //---------------------------------------------------------------------------
140 * Determine edges going out of a loop (= edges that go to a block that is not inside
141 * the loop or one of its subloops)
143 static INLINE void construct_loop_out_edges(ir_node* block, void* e) {
144 morgan_env_t *env = (morgan_env_t*) e;
145 int n_cfgpreds = get_Block_n_cfgpreds(block);
147 ir_loop* loop = get_irn_loop(block);
149 for(i = 0; i < n_cfgpreds; ++i) {
150 ir_node* cfgpred = get_Block_cfgpred(block, i);
151 ir_node* cfgpred_block = get_nodes_block(cfgpred);
152 ir_loop* cfgpred_loop = get_irn_loop(cfgpred_block);
153 loop_attr_t *outedges = get_loop_attr(env, cfgpred_loop);
155 if(cfgpred_loop != loop && get_loop_depth(cfgpred_loop) >= get_loop_depth(loop)) {
156 loop_out_edge_t edge;
159 set_insert(outedges->out_edges, &edge, sizeof(edge), loop_out_edge_hash(&edge));
164 static void free_loop_out_edges(morgan_env_t *env) {
167 for(l_attr = set_first(env->loop_attr_set); l_attr != NULL; l_attr = set_next(env->loop_attr_set)) {
168 del_set(l_attr->out_edges);
173 * Debugging help, shows all nodes in a (node-)bitset
175 static void show_nodebitset(ir_graph* irg, bitset_t* bitset) {
178 bitset_foreach(bitset, i) {
179 ir_node* node = get_idx_irn(irg, i);
180 DBG((dbg, DBG_LIVE, "\t%+F\n", node));
185 * Construct the livethrough unused set for a block
187 static bitset_t *construct_block_livethrough_unused(morgan_env_t* env, ir_node* block) {
188 block_attr_t *block_attr = get_block_attr(env, block);
192 DBG((dbg, DBG_LIVE, "Processing block %d\n", get_irn_node_nr(block)));
193 // copy all live-outs into the livethrough_unused set
194 live_foreach(block, li) {
197 if(!live_is_in(li) || !live_is_out(li))
199 if(!arch_irn_consider_in_reg_alloc(env->arch, env->cls, li->irn))
202 node_idx = get_irn_idx(li->irn);
203 bitset_set(block_attr->livethrough_unused, node_idx);
207 * All values that are used within the block are not unused (and therefore not
208 * livethrough_unused)
210 sched_foreach(block, node) {
213 for(i = 0, arity = get_irn_arity(node); i < arity; ++i) {
214 int idx = get_irn_idx(get_irn_n(node, i));
215 bitset_clear(block_attr->livethrough_unused, idx);
219 show_nodebitset(env->irg, block_attr->livethrough_unused);
220 return block_attr->livethrough_unused;
224 * Construct the livethrough unused set for a loop (and all its subloops+blocks)
226 static bitset_t *construct_loop_livethrough_unused(morgan_env_t *env, ir_loop *loop) {
228 loop_attr_t* loop_attr = get_loop_attr(env, loop);
230 DBG((dbg, DBG_LIVE, "Processing Loop %d\n", loop->loop_nr));
231 assert(get_loop_n_elements(loop) > 0);
232 for(i = 0; i < get_loop_n_elements(loop); ++i) {
233 loop_element elem = get_loop_element(loop, i);
234 switch (*elem.kind) {
236 bitset_t *livethrough_block_unused;
237 assert(is_Block(elem.node));
238 livethrough_block_unused = construct_block_livethrough_unused(env, elem.node);
240 bitset_copy(loop_attr->livethrough_unused, livethrough_block_unused);
242 bitset_and(loop_attr->livethrough_unused, livethrough_block_unused);
247 bitset_t *livethrough_son_unused;
249 livethrough_son_unused = construct_loop_livethrough_unused(env, elem.son);
251 bitset_copy(loop_attr->livethrough_unused, livethrough_son_unused);
253 bitset_and(loop_attr->livethrough_unused, livethrough_son_unused);
262 DBG((dbg, DBG_LIVE, "Done with loop %d\n", loop->loop_nr));
264 // remove all unused livethroughs that are remembered for this loop from child loops and blocks
265 for(i = 0; i < get_loop_n_elements(loop); ++i) {
266 const loop_element elem = get_loop_element(loop, i);
268 if(*elem.kind == k_ir_loop) {
269 loop_attr_t *son_attr = get_loop_attr(env, elem.son);
270 bitset_andnot(son_attr->livethrough_unused, loop_attr->livethrough_unused);
272 DBG((dbg, DBG_LIVE, "Livethroughs for loop %d:\n", loop->loop_nr));
273 show_nodebitset(env->irg, son_attr->livethrough_unused);
274 } else if(*elem.kind == k_ir_node) {
275 block_attr_t *block_attr = get_block_attr(env, elem.node);
276 bitset_andnot(block_attr->livethrough_unused, loop_attr->livethrough_unused);
278 DBG((dbg, DBG_LIVE, "Livethroughs for block %+F\n", elem.node));
279 show_nodebitset(env->irg, block_attr->livethrough_unused);
285 return loop_attr->livethrough_unused;
288 //---------------------------------------------------------------------------
290 static int reduce_register_pressure_in_block(morgan_env_t *env, ir_node* block, int loop_unused_spills_possible) {
293 int max_pressure = 0;
295 int loop_unused_spills_needed;
296 block_attr_t *block_attr = get_block_attr(env, block);
297 int block_unused_spills_possible = bitset_popcnt(block_attr->livethrough_unused);
298 int unused_spills_possible = loop_unused_spills_possible + block_unused_spills_possible;
299 pset *live_nodes = pset_new_ptr_default();
301 be_liveness_end_of_block(env->arch, env->cls, block, live_nodes);
302 pressure = pset_count(live_nodes);
304 DBG((dbg, DBG_LIVE, "Reduce pressure to %d In Block %+F:\n", env->registers_available, block));
307 * Walk over all irns in the schedule and check register pressure for each of them
309 sched_foreach_reverse(block, irn) {
310 // do we need more spills than possible with unused libethroughs?
311 int spills_needed = pressure - unused_spills_possible - env->registers_available;
312 if(spills_needed > 0) {
313 DBG((dbg, DBG_PRESSURE, "\tWARNING %d more spills needed at %+F\n", spills_needed, irn));
314 // TODO further spills needed
317 if(pressure > max_pressure) {
318 max_pressure = pressure;
321 /* Register pressure is only important until we reach the first phi (the rest of the block
322 * will only be phis.)
329 int pressure_old = pressure;
330 be_liveness_transfer(env->arch, env->cls, irn, live_nodes);
331 pressure = pset_count(live_nodes);
332 DBG((dbg, DBG_PRESSURE, "\tPressure at %+F - before: %d after: %d\n", irn, pressure_old, pressure));
337 * Calculate number of spills from loop_unused_spills_possible that we want to use,
338 * and spill unused livethroughs from the block if we still don't have enough registers
340 spills_needed = max_pressure - env->registers_available;
341 if(spills_needed < 0) {
342 loop_unused_spills_needed = 0;
343 } else if(spills_needed > loop_unused_spills_possible) {
345 int block_unused_spills_needed;
347 loop_unused_spills_needed = loop_unused_spills_possible;
348 block_unused_spills_needed = spills_needed - loop_unused_spills_possible;
349 if(block_unused_spills_needed > block_unused_spills_possible) {
350 block_unused_spills_needed = block_unused_spills_possible;
355 * Spill/Reload unused livethroughs from the block
357 bitset_foreach(block_attr->livethrough_unused, i) {
359 const ir_edge_t *edge;
361 if(spills >= block_unused_spills_needed)
364 to_spill = get_idx_irn(env->irg, i);
365 foreach_block_succ(block, edge) {
366 DBG((dbg, DBG_PRESSURE, "Spilling node %+F around block %+F\n", to_spill, block));
367 if(is_Phi(to_spill)) {
368 be_spill_phi(env->senv, to_spill);
370 be_add_reload_on_edge(env->senv, to_spill, edge->src, edge->pos);
374 loop_unused_spills_needed = spills_needed;
377 del_pset(live_nodes);
379 DBG((dbg, DBG_PRESSURE, "Unused spills for Block %+F needed: %d\n", block, loop_unused_spills_needed));
380 return loop_unused_spills_needed;
384 * Reduce register pressure in a loop
386 * @param unused_spills_possible Number of spills from livethrough_unused variables possible in outer loops
387 * @return Number of spills of livethrough_unused variables needed in outer loops
389 static int reduce_register_pressure_in_loop(morgan_env_t *env, ir_loop *loop, int outer_spills_possible) {
391 loop_attr_t* loop_attr = get_loop_attr(env, loop);
392 int spills_needed = 0;
393 int spills_possible = outer_spills_possible + bitset_popcnt(loop_attr->livethrough_unused);
394 int outer_spills_needed;
396 DBG((dbg, DBG_PRESSURE, "Reducing Pressure in loop %d\n", loop->loop_nr));
397 for(i = 0; i < get_loop_n_elements(loop); ++i) {
398 loop_element elem = get_loop_element(loop, i);
399 switch (*elem.kind) {
402 assert(is_Block(elem.node));
403 needed = reduce_register_pressure_in_block(env, elem.node, spills_possible);
404 assert(needed <= spills_possible);
405 if(needed > spills_needed)
406 spills_needed = needed;
410 int needed = reduce_register_pressure_in_loop(env, elem.son, spills_possible);
411 assert(needed <= spills_possible);
412 if(needed > spills_needed)
413 spills_needed = needed;
422 // calculate number of spills needed in outer loop and spill
423 // unused livethrough nodes around this loop
424 if(spills_needed > outer_spills_possible) {
425 outer_spills_needed = outer_spills_possible;
426 spills_needed -= outer_spills_possible;
428 bitset_foreach(loop_attr->livethrough_unused, i) {
429 loop_out_edge_t *edge;
430 ir_node *to_spill = get_idx_irn(env->irg, i);
432 for(edge = set_first(loop_attr->out_edges); edge != NULL; edge = set_next(loop_attr->out_edges)) {
433 if(is_Phi(to_spill)) {
434 be_spill_phi(env->senv, to_spill);
437 be_add_reload_on_edge(env->senv, to_spill, edge->block, edge->pos);
441 outer_spills_needed = spills_needed;
444 return outer_spills_needed;
447 static void *init_phase_data(phase_t *phase, ir_node *irn, void *old) {
451 void be_spill_morgan(const be_chordal_env_t *chordal_env) {
454 FIRM_DBG_REGISTER(dbg, "ir.be.spillmorgan");
456 env.arch = chordal_env->birg->main_env->arch_env;
457 env.irg = chordal_env->irg;
458 env.cls = chordal_env->cls;
459 env.senv = be_new_spill_env(chordal_env);
460 DEBUG_ONLY(be_set_spill_env_dbg_module(env.senv, dbg);)
462 phase_init(&env.phase, "spillmorgan", env.irg, PHASE_DEFAULT_GROWTH, init_phase_data);
464 env.registers_available = arch_count_non_ignore_regs(env.arch, env.cls);
466 env.loop_attr_set = new_set(loop_attr_cmp, 5);
467 env.block_attr_set = new_set(block_attr_cmp, 20);
469 /*-- Part1: Analysis --*/
470 be_liveness(env.irg);
472 // construct control flow loop tree
473 construct_cf_backedges(chordal_env->irg);
475 // construct loop out edges and livethrough_unused sets for loops and blocks
476 irg_block_walk_graph(chordal_env->irg, construct_loop_out_edges, NULL, &env);
477 construct_loop_livethrough_unused(&env, get_irg_loop(env.irg));
479 /*-- Part2: Transformation --*/
481 // reduce register pressure to number of available registers
482 reduce_register_pressure_in_loop(&env, get_irg_loop(env.irg), 0);
484 be_insert_spills_reloads(env.senv);
485 if (chordal_env->opts->vrfy_option == BE_CH_VRFY_WARN) {
486 be_verify_schedule(env.irg);
487 } else if (chordal_env->opts->vrfy_option == BE_CH_VRFY_ASSERT) {
488 assert(be_verify_schedule(env.irg));
491 // we have to remove dead nodes from schedule to not confuse liveness calculation
492 be_remove_dead_nodes_from_schedule(env.irg);
495 be_dump(env.irg, "-spillmorgan", dump_ir_block_graph_sched);
496 free_loop_out_edges(&env);
497 del_set(env.loop_attr_set);
498 del_set(env.block_attr_set);
500 // fix the remaining places with too high register pressure with beladies algorithm
501 be_liveness(env.irg);
502 be_spill_belady_spill_env(chordal_env, env.senv);
504 be_delete_spill_env(env.senv);
505 phase_free(&env.phase);