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"
23 #include "interval_analysis.h"
27 #include "irgraph_t.h"
29 #include "irphase_t.h"
32 #include "bespillbelady.h"
36 #define DBG_PRESSURE 2
37 DEBUG_ONLY(static firm_dbg_module_t *dbg = NULL;)
39 typedef struct _morgan_env_t {
40 const arch_env_t *arch;
41 const arch_register_class_t *cls;
44 // maximum safe register pressure
45 int registers_available;
54 typedef struct _loop_out_edge_t {
59 typedef struct _loop_attr_t {
62 /// The set of all values that live through the loop and are not used
63 bitset_t *livethrough_unused;
66 typedef struct _block_attr_t {
68 bitset_t *livethrough_unused;
71 //---------------------------------------------------------------------------
73 int loop_out_edge_cmp(const void* p1, const void* p2, size_t s) {
74 loop_out_edge_t *e1 = (loop_out_edge_t*) p1;
75 loop_out_edge_t *e2 = (loop_out_edge_t*) p2;
77 return e1->block != e2->block || e1->pos != e2->pos;
80 int loop_attr_cmp(const void *e1, const void *e2, size_t s) {
81 loop_attr_t *la1 = (loop_attr_t*) e1;
82 loop_attr_t *la2 = (loop_attr_t*) e2;
84 return la1->loop != la2->loop;
87 int block_attr_cmp(const void *e1, const void *e2, size_t s) {
88 block_attr_t *b1 = (block_attr_t*) e1;
89 block_attr_t *b2 = (block_attr_t*) e2;
91 return b1->block != b2->block;
94 static INLINE int loop_attr_hash(const loop_attr_t *a) {
95 return HASH_PTR(a->loop);
98 static INLINE int block_attr_hash(const block_attr_t *b) {
99 return HASH_PTR(b->block);
102 static INLINE int loop_out_edge_hash(const loop_out_edge_t *e) {
103 return HASH_PTR(e->block) ^ (e->pos * 31);
106 static INLINE loop_attr_t *get_loop_attr(morgan_env_t *env, ir_loop *loop) {
107 loop_attr_t l_attr, *res;
111 hash = loop_attr_hash(&l_attr);
112 res = set_find(env->loop_attr_set, &l_attr, sizeof(l_attr), hash);
114 // create new loop_attr if none exists yet
116 l_attr.out_edges = new_set(loop_out_edge_cmp, 1);
117 l_attr.livethrough_unused = bitset_obstack_alloc(&env->phase.obst, get_irg_last_idx(env->irg));
118 res = set_insert(env->loop_attr_set, &l_attr, sizeof(l_attr), hash);
124 static INLINE block_attr_t *get_block_attr(morgan_env_t *env, ir_node *block) {
125 block_attr_t b_attr, *res;
127 b_attr.block = block;
129 hash = block_attr_hash(&b_attr);
130 res = set_find(env->block_attr_set, &b_attr, sizeof(b_attr), hash);
133 b_attr.livethrough_unused = bitset_obstack_alloc(&env->phase.obst, get_irg_last_idx(env->irg));
134 res = set_insert(env->block_attr_set, &b_attr, sizeof(b_attr), hash);
140 //---------------------------------------------------------------------------
143 * Determine edges going out of a loop (= edges that go to a block that is not inside
144 * the loop or one of its subloops)
146 static INLINE void construct_loop_out_edges(ir_node* block, void* e) {
147 morgan_env_t *env = (morgan_env_t*) e;
148 int n_cfgpreds = get_Block_n_cfgpreds(block);
150 ir_loop* loop = get_irn_loop(block);
152 for(i = 0; i < n_cfgpreds; ++i) {
153 ir_node* cfgpred = get_Block_cfgpred(block, i);
154 ir_node* cfgpred_block = get_nodes_block(cfgpred);
155 ir_loop* cfgpred_loop = get_irn_loop(cfgpred_block);
156 loop_attr_t *outedges = get_loop_attr(env, cfgpred_loop);
158 if(cfgpred_loop != loop && get_loop_depth(cfgpred_loop) >= get_loop_depth(loop)) {
159 loop_out_edge_t edge;
162 set_insert(outedges->out_edges, &edge, sizeof(edge), loop_out_edge_hash(&edge));
167 static void free_loop_out_edges(morgan_env_t *env) {
170 for(l_attr = set_first(env->loop_attr_set); l_attr != NULL; l_attr = set_next(env->loop_attr_set)) {
171 del_set(l_attr->out_edges);
176 * Debugging help, shows all nodes in a (node-)bitset
178 static void show_nodebitset(ir_graph* irg, bitset_t* bitset) {
181 bitset_foreach(bitset, i) {
182 ir_node* node = get_idx_irn(irg, i);
183 DBG((dbg, DBG_LIVE, "\t%+F\n", node));
188 * Construct the livethrough unused information for a block
190 static bitset_t *construct_block_livethrough_unused(morgan_env_t* env, ir_node* block) {
191 block_attr_t *block_attr = get_block_attr(env, block);
195 DBG((dbg, DBG_LIVE, "Processing block %d\n", get_irn_node_nr(block)));
196 // copy all live-outs into the livethrough_unused set
197 live_foreach(block, li) {
200 if(!live_is_in(li) || !live_is_out(li))
202 if(!arch_irn_consider_in_reg_alloc(env->arch, env->cls, li->irn))
205 node_idx = get_irn_idx(li->irn);
206 bitset_set(block_attr->livethrough_unused, node_idx);
210 * All values that are used within the block are not unused (and therefore not
211 * livethrough_unused)
213 sched_foreach(block, node) {
216 for(i = 0, arity = get_irn_arity(node); i < arity; ++i) {
217 int idx = get_irn_idx(get_irn_n(node, i));
218 bitset_clear(block_attr->livethrough_unused, idx);
222 show_nodebitset(env->irg, block_attr->livethrough_unused);
223 return block_attr->livethrough_unused;
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 be_add_reload_on_edge(env->senv, to_spill, edge->src, edge->pos);
371 loop_unused_spills_needed = spills_needed;
374 del_pset(live_nodes);
376 DBG((dbg, DBG_PRESSURE, "Unused spills for Block %+F needed: %d\n", block, loop_unused_spills_needed));
377 return loop_unused_spills_needed;
381 * Reduce register pressure in a loop
383 * @param unused_spills_possible Number of spills from livethrough_unused variables possible in outer loops
384 * @return Number of spills of livethrough_unused variables needed in outer loops
386 static int reduce_register_pressure_in_loop(morgan_env_t *env, ir_loop *loop, int outer_spills_possible) {
388 loop_attr_t* loop_attr = get_loop_attr(env, loop);
389 int spills_needed = 0;
390 int spills_possible = outer_spills_possible + bitset_popcnt(loop_attr->livethrough_unused);
391 int outer_spills_needed;
393 DBG((dbg, DBG_PRESSURE, "Reducing Pressure in loop %d\n", loop->loop_nr));
394 for(i = 0; i < get_loop_n_elements(loop); ++i) {
395 loop_element elem = get_loop_element(loop, i);
396 switch (*elem.kind) {
399 assert(is_Block(elem.node));
400 needed = reduce_register_pressure_in_block(env, elem.node, spills_possible);
401 assert(needed <= spills_possible);
402 if(needed > spills_needed)
403 spills_needed = needed;
407 int needed = reduce_register_pressure_in_loop(env, elem.son, spills_possible);
408 assert(needed <= spills_possible);
409 if(needed > spills_needed)
410 spills_needed = needed;
419 // calculate number of spills needed in outer loop and spill
420 // unused livethrough nodes around this loop
421 if(spills_needed > outer_spills_possible) {
422 outer_spills_needed = outer_spills_possible;
423 spills_needed -= outer_spills_possible;
425 bitset_foreach(loop_attr->livethrough_unused, i) {
426 loop_out_edge_t *edge;
427 ir_node *to_spill = get_idx_irn(env->irg, i);
429 for(edge = set_first(loop_attr->out_edges); edge != NULL; edge = set_next(loop_attr->out_edges)) {
430 if(is_Phi(to_spill)) {
431 be_spill_phi(env->senv, to_spill);
434 be_add_reload_on_edge(env->senv, to_spill, edge->block, edge->pos);
438 outer_spills_needed = spills_needed;
441 return outer_spills_needed;
444 static void *init_phase_data(phase_t *phase, ir_node *irn, void *old) {
448 void be_spill_morgan(const be_chordal_env_t *chordal_env) {
451 FIRM_DBG_REGISTER(dbg, "ir.be.spillmorgan");
453 env.arch = chordal_env->birg->main_env->arch_env;
454 env.irg = chordal_env->irg;
455 env.cls = chordal_env->cls;
456 env.senv = be_new_spill_env(chordal_env);
457 DEBUG_ONLY(be_set_spill_env_dbg_module(env.senv, dbg);)
458 env.uses = be_begin_uses(env.irg, env.arch, env.cls);
460 phase_init(&env.phase, "spillmorgan", env.irg, PHASE_DEFAULT_GROWTH, init_phase_data);
462 env.registers_available = arch_count_non_ignore_regs(env.arch, env.cls);
464 env.loop_attr_set = new_set(loop_attr_cmp, 5);
465 env.block_attr_set = new_set(block_attr_cmp, 20);
467 /*-- Part1: Analysis --*/
468 be_liveness(env.irg);
470 // construct control flow loop tree
471 construct_cf_backedges(chordal_env->irg);
473 // construct loop out edges and livethrough_unused sets for loops and blocks
474 irg_block_walk_graph(chordal_env->irg, construct_loop_out_edges, NULL, &env);
475 construct_loop_livethrough_unused(&env, get_irg_loop(env.irg));
477 /*-- Part2: Transformation --*/
479 // reduce register pressure to number of available registers
480 reduce_register_pressure_in_loop(&env, get_irg_loop(env.irg), 0);
482 be_insert_spills_reloads(env.senv);
483 if (chordal_env->opts->vrfy_option == BE_CH_VRFY_WARN) {
484 be_verify_schedule(env.irg);
485 } else if (chordal_env->opts->vrfy_option == BE_CH_VRFY_ASSERT) {
486 assert(be_verify_schedule(env.irg));
490 be_end_uses(env.uses);
491 be_dump(env.irg, "-spillmorgan", dump_ir_block_graph_sched);
492 free_loop_out_edges(&env);
493 del_set(env.loop_attr_set);
494 del_set(env.block_attr_set);
496 // fix the remaining places with too high register pressure with beladies algorithm
498 // we have to remove dead nodes from schedule to not confuse liveness calculation
499 be_remove_dead_nodes_from_schedule(env.irg);
500 be_liveness(env.irg);
501 be_spill_belady_spill_env(chordal_env, env.senv);
503 be_delete_spill_env(env.senv);
504 phase_free(&env.phase);