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_t.h"
21 #include "irgraph_t.h"
22 #include "irphase_t.h"
25 #include "bespillbelady.h"
29 #define DBG_PRESSURE 2
30 DEBUG_ONLY(static firm_dbg_module_t *dbg = NULL;)
32 typedef struct _morgan_env_t {
33 const arch_env_t *arch;
34 const arch_register_class_t *cls;
37 // maximum safe register pressure
38 int registers_available;
46 typedef struct _loop_out_edge_t {
51 typedef struct _loop_attr_t {
54 /// The set of all values that live through the loop and are not used
55 bitset_t *livethrough_unused;
58 typedef struct _block_attr_t {
60 bitset_t *livethrough_unused;
63 //---------------------------------------------------------------------------
65 int loop_out_edge_cmp(const void* p1, const void* p2, size_t s) {
66 loop_out_edge_t *e1 = (loop_out_edge_t*) p1;
67 loop_out_edge_t *e2 = (loop_out_edge_t*) p2;
69 return e1->block != e2->block || e1->pos != e2->pos;
72 int loop_attr_cmp(const void *e1, const void *e2, size_t s) {
73 loop_attr_t *la1 = (loop_attr_t*) e1;
74 loop_attr_t *la2 = (loop_attr_t*) e2;
76 return la1->loop != la2->loop;
79 int block_attr_cmp(const void *e1, const void *e2, size_t s) {
80 block_attr_t *b1 = (block_attr_t*) e1;
81 block_attr_t *b2 = (block_attr_t*) e2;
83 return b1->block != b2->block;
86 static INLINE int loop_attr_hash(const loop_attr_t *a) {
87 return HASH_PTR(a->loop);
90 static INLINE int block_attr_hash(const block_attr_t *b) {
91 return HASH_PTR(b->block);
94 static INLINE int loop_out_edge_hash(const loop_out_edge_t *e) {
95 return HASH_PTR(e->block) ^ (e->pos * 31);
98 static INLINE loop_attr_t *get_loop_attr(morgan_env_t *env, ir_loop *loop) {
99 loop_attr_t l_attr, *res;
103 hash = loop_attr_hash(&l_attr);
104 res = set_find(env->loop_attr_set, &l_attr, sizeof(l_attr), hash);
106 // create new loop_attr if none exists yet
108 l_attr.out_edges = new_set(loop_out_edge_cmp, 1);
109 l_attr.livethrough_unused = bitset_obstack_alloc(&env->phase.obst, get_irg_last_idx(env->irg));
110 res = set_insert(env->loop_attr_set, &l_attr, sizeof(l_attr), hash);
116 static INLINE block_attr_t *get_block_attr(morgan_env_t *env, ir_node *block) {
117 block_attr_t b_attr, *res;
119 b_attr.block = block;
121 hash = block_attr_hash(&b_attr);
122 res = set_find(env->block_attr_set, &b_attr, sizeof(b_attr), hash);
125 b_attr.livethrough_unused = bitset_obstack_alloc(&env->phase.obst, get_irg_last_idx(env->irg));
126 res = set_insert(env->block_attr_set, &b_attr, sizeof(b_attr), hash);
132 //---------------------------------------------------------------------------
134 static INLINE int consider_for_spilling(const arch_env_t *env, const arch_register_class_t *cls, const ir_node *node) {
135 if(!arch_irn_has_reg_class(env, node, -1, cls))
138 return !(arch_irn_get_flags(env, node) & (arch_irn_flags_ignore | arch_irn_flags_dont_spill));
142 * Determine edges going out of a loop (= edges that go to a block that is not inside
143 * the loop or one of its subloops)
145 static INLINE void construct_loop_out_edges(ir_node* block, void* e) {
146 morgan_env_t *env = (morgan_env_t*) e;
147 int n_cfgpreds = get_Block_n_cfgpreds(block);
149 ir_loop* loop = get_irn_loop(block);
151 for(i = 0; i < n_cfgpreds; ++i) {
152 ir_node* cfgpred = get_Block_cfgpred(block, i);
153 ir_node* cfgpred_block = get_nodes_block(cfgpred);
154 ir_loop* cfgpred_loop = get_irn_loop(cfgpred_block);
155 loop_attr_t *outedges = get_loop_attr(env, cfgpred_loop);
157 if(cfgpred_loop != loop && get_loop_depth(cfgpred_loop) >= get_loop_depth(loop)) {
158 loop_out_edge_t edge;
161 set_insert(outedges->out_edges, &edge, sizeof(edge), loop_out_edge_hash(&edge));
166 static void free_loop_out_edges(morgan_env_t *env) {
169 for(l_attr = set_first(env->loop_attr_set); l_attr != NULL; l_attr = set_next(env->loop_attr_set)) {
170 del_set(l_attr->out_edges);
175 * Debugging help, shows all nodes in a (node-)bitset
177 static void show_nodebitset(ir_graph* irg, bitset_t* bitset) {
180 bitset_foreach(bitset, i) {
181 ir_node* node = get_idx_irn(irg, i);
182 DBG((dbg, DBG_LIVE, "\t%+F\n", node));
187 * Construct the livethrough unused set for a block
189 static bitset_t *construct_block_livethrough_unused(morgan_env_t* env, ir_node* block) {
190 block_attr_t *block_attr = get_block_attr(env, block);
194 DBG((dbg, DBG_LIVE, "Processing block %d\n", get_irn_node_nr(block)));
195 // copy all live-outs into the livethrough_unused set
196 live_foreach(block, li) {
199 if(!live_is_in(li) || !live_is_out(li))
201 if(!consider_for_spilling(env->arch, env->cls, li->irn))
204 node_idx = get_irn_idx(li->irn);
205 bitset_set(block_attr->livethrough_unused, node_idx);
209 * All values that are used within the block are not unused (and therefore not
210 * livethrough_unused)
212 sched_foreach(block, node) {
215 for(i = 0, arity = get_irn_arity(node); i < arity; ++i) {
216 int idx = get_irn_idx(get_irn_n(node, i));
217 bitset_clear(block_attr->livethrough_unused, idx);
221 show_nodebitset(env->irg, block_attr->livethrough_unused);
222 return block_attr->livethrough_unused;
226 * Construct the livethrough unused set for a loop (and all its subloops+blocks)
228 static bitset_t *construct_loop_livethrough_unused(morgan_env_t *env, ir_loop *loop) {
230 loop_attr_t* loop_attr = get_loop_attr(env, loop);
232 DBG((dbg, DBG_LIVE, "Processing Loop %d\n", loop->loop_nr));
233 assert(get_loop_n_elements(loop) > 0);
234 for(i = 0; i < get_loop_n_elements(loop); ++i) {
235 loop_element elem = get_loop_element(loop, i);
236 switch (*elem.kind) {
238 bitset_t *livethrough_block_unused;
239 assert(is_Block(elem.node));
240 livethrough_block_unused = construct_block_livethrough_unused(env, elem.node);
242 bitset_copy(loop_attr->livethrough_unused, livethrough_block_unused);
244 bitset_and(loop_attr->livethrough_unused, livethrough_block_unused);
249 bitset_t *livethrough_son_unused;
251 livethrough_son_unused = construct_loop_livethrough_unused(env, elem.son);
253 bitset_copy(loop_attr->livethrough_unused, livethrough_son_unused);
255 bitset_and(loop_attr->livethrough_unused, livethrough_son_unused);
264 DBG((dbg, DBG_LIVE, "Done with loop %d\n", loop->loop_nr));
266 // remove all unused livethroughs that are remembered for this loop from child loops and blocks
267 for(i = 0; i < get_loop_n_elements(loop); ++i) {
268 const loop_element elem = get_loop_element(loop, i);
270 if(*elem.kind == k_ir_loop) {
271 loop_attr_t *son_attr = get_loop_attr(env, elem.son);
272 bitset_andnot(son_attr->livethrough_unused, loop_attr->livethrough_unused);
274 DBG((dbg, DBG_LIVE, "Livethroughs for loop %d:\n", loop->loop_nr));
275 show_nodebitset(env->irg, son_attr->livethrough_unused);
276 } else if(*elem.kind == k_ir_node) {
277 block_attr_t *block_attr = get_block_attr(env, elem.node);
278 bitset_andnot(block_attr->livethrough_unused, loop_attr->livethrough_unused);
280 DBG((dbg, DBG_LIVE, "Livethroughs for block %+F\n", elem.node));
281 show_nodebitset(env->irg, block_attr->livethrough_unused);
287 return loop_attr->livethrough_unused;
290 //---------------------------------------------------------------------------
292 static int reduce_register_pressure_in_block(morgan_env_t *env, ir_node* block, int loop_unused_spills_possible) {
295 int max_pressure = 0;
297 int loop_unused_spills_needed;
298 block_attr_t *block_attr = get_block_attr(env, block);
299 int block_unused_spills_possible = bitset_popcnt(block_attr->livethrough_unused);
300 int unused_spills_possible = loop_unused_spills_possible + block_unused_spills_possible;
301 pset *live_nodes = pset_new_ptr_default();
303 be_liveness_end_of_block(env->arch, env->cls, block, live_nodes);
304 pressure = pset_count(live_nodes);
306 DBG((dbg, DBG_LIVE, "Reduce pressure to %d In Block %+F:\n", env->registers_available, block));
309 * Walk over all irns in the schedule and check register pressure for each of them
311 sched_foreach_reverse(block, irn) {
312 // do we need more spills than possible with unused libethroughs?
313 int spills_needed = pressure - env->registers_available - unused_spills_possible;
314 if(spills_needed > 0) {
315 DBG((dbg, DBG_PRESSURE, "\tWARNING %d more spills needed at %+F\n", spills_needed, irn));
316 // TODO further spills needed
319 if(pressure > max_pressure) {
320 max_pressure = pressure;
323 /* Register pressure is only important until we reach the first phi (the rest of the block
324 * will only be phis.)
330 be_liveness_transfer(env->arch, env->cls, irn, live_nodes);
331 pressure = pset_count(live_nodes);
334 DBG((dbg, DBG_PRESSURE, "\tMax Pressure in %+F: %d\n", block, max_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 be_add_reload_on_edge(env->senv, to_spill, edge->src, edge->pos);
372 loop_unused_spills_needed = spills_needed;
375 del_pset(live_nodes);
377 DBG((dbg, DBG_PRESSURE, "Unused spills for Block %+F needed: %d\n", block, loop_unused_spills_needed));
378 return loop_unused_spills_needed;
382 * Reduce register pressure in a loop
384 * @param unused_spills_possible Number of spills from livethrough_unused variables possible in outer loops
385 * @return Number of spills of livethrough_unused variables needed in outer loops
387 static int reduce_register_pressure_in_loop(morgan_env_t *env, ir_loop *loop, int outer_spills_possible) {
389 loop_attr_t* loop_attr = get_loop_attr(env, loop);
390 int spills_needed = 0;
391 int spills_possible = outer_spills_possible + bitset_popcnt(loop_attr->livethrough_unused);
392 int outer_spills_needed;
394 DBG((dbg, DBG_PRESSURE, "Reducing Pressure in loop %d\n", loop->loop_nr));
395 for(i = 0; i < get_loop_n_elements(loop); ++i) {
396 loop_element elem = get_loop_element(loop, i);
397 switch (*elem.kind) {
400 assert(is_Block(elem.node));
401 needed = reduce_register_pressure_in_block(env, elem.node, spills_possible);
402 assert(needed <= spills_possible);
403 if(needed > spills_needed)
404 spills_needed = needed;
408 int needed = reduce_register_pressure_in_loop(env, elem.son, spills_possible);
409 assert(needed <= spills_possible);
410 if(needed > spills_needed)
411 spills_needed = needed;
420 // calculate number of spills needed in outer loop and spill
421 // unused livethrough nodes around this loop
422 if(spills_needed > outer_spills_possible) {
423 outer_spills_needed = outer_spills_possible;
424 spills_needed -= outer_spills_possible;
426 bitset_foreach(loop_attr->livethrough_unused, i) {
427 loop_out_edge_t *edge;
428 ir_node *to_spill = get_idx_irn(env->irg, i);
430 for(edge = set_first(loop_attr->out_edges); edge != NULL; edge = set_next(loop_attr->out_edges)) {
431 be_add_reload_on_edge(env->senv, to_spill, edge->block, edge->pos);
435 outer_spills_needed = spills_needed;
438 return outer_spills_needed;
441 static void *init_phase_data(phase_t *phase, ir_node *irn, void *old) {
445 void be_spill_morgan(const be_chordal_env_t *chordal_env) {
448 FIRM_DBG_REGISTER(dbg, "ir.be.spillmorgan");
450 env.arch = chordal_env->birg->main_env->arch_env;
451 env.irg = chordal_env->irg;
452 env.cls = chordal_env->cls;
453 env.senv = be_new_spill_env(chordal_env);
454 DEBUG_ONLY(be_set_spill_env_dbg_module(env.senv, dbg);)
456 phase_init(&env.phase, "spillmorgan", env.irg, PHASE_DEFAULT_GROWTH, init_phase_data);
458 env.registers_available = arch_count_non_ignore_regs(env.arch, env.cls);
460 env.loop_attr_set = new_set(loop_attr_cmp, 5);
461 env.block_attr_set = new_set(block_attr_cmp, 20);
463 /*-- Part1: Analysis --*/
464 be_liveness(env.irg);
466 // construct control flow loop tree
467 construct_cf_backedges(chordal_env->irg);
469 // construct loop out edges and livethrough_unused sets for loops and blocks
470 irg_block_walk_graph(chordal_env->irg, construct_loop_out_edges, NULL, &env);
471 construct_loop_livethrough_unused(&env, get_irg_loop(env.irg));
473 /*-- Part2: Transformation --*/
475 // reduce register pressure to number of available registers
476 reduce_register_pressure_in_loop(&env, get_irg_loop(env.irg), 0);
478 be_insert_spills_reloads(env.senv);
479 if (chordal_env->opts->vrfy_option == BE_CH_VRFY_WARN) {
480 be_verify_schedule(env.irg);
481 } else if (chordal_env->opts->vrfy_option == BE_CH_VRFY_ASSERT) {
482 assert(be_verify_schedule(env.irg));
485 // we have to remove dead nodes from schedule to not confuse liveness calculation
486 be_remove_dead_nodes_from_schedule(env.irg);
489 be_dump(env.irg, "-spillmorgan", dump_ir_block_graph_sched);
490 free_loop_out_edges(&env);
491 del_set(env.loop_attr_set);
492 del_set(env.block_attr_set);
494 // fix the remaining places with too high register pressure with beladies algorithm
495 be_liveness(env.irg);
496 be_spill_belady_spill_env(chordal_env, env.senv);
498 be_delete_spill_env(env.senv);
499 phase_free(&env.phase);