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"
24 #include "interval_analysis.h"
28 #include "irgraph_t.h"
30 #include "irphase_t.h"
33 #include "bespillbelady.h"
37 #define DBG_PRESSURE 2
38 DEBUG_ONLY(static firm_dbg_module_t *dbg = NULL;)
40 typedef struct _morgan_env_t {
41 const arch_env_t *arch;
42 const arch_register_class_t *cls;
45 // maximum safe register pressure
46 int registers_available;
48 be_insn_env_t insn_env;
56 typedef struct _loop_out_edge_t {
61 typedef struct _loop_attr_t {
64 /// The set of all values that live through the loop and are not used
65 bitset_t *livethrough_unused;
68 typedef struct _block_attr_t {
70 bitset_t *livethrough_unused;
73 //---------------------------------------------------------------------------
75 int loop_out_edge_cmp(const void* p1, const void* p2, size_t s) {
76 loop_out_edge_t *e1 = (loop_out_edge_t*) p1;
77 loop_out_edge_t *e2 = (loop_out_edge_t*) p2;
79 return e1->block != e2->block || e1->pos != e2->pos;
82 int loop_attr_cmp(const void *e1, const void *e2, size_t s) {
83 loop_attr_t *la1 = (loop_attr_t*) e1;
84 loop_attr_t *la2 = (loop_attr_t*) e2;
86 return la1->loop != la2->loop;
89 int block_attr_cmp(const void *e1, const void *e2, size_t s) {
90 block_attr_t *b1 = (block_attr_t*) e1;
91 block_attr_t *b2 = (block_attr_t*) e2;
93 return b1->block != b2->block;
96 static INLINE int loop_attr_hash(const loop_attr_t *a) {
97 return HASH_PTR(a->loop);
100 static INLINE int block_attr_hash(const block_attr_t *b) {
101 return HASH_PTR(b->block);
104 static INLINE int loop_out_edge_hash(const loop_out_edge_t *e) {
105 return HASH_PTR(e->block) ^ (e->pos * 31);
108 static INLINE loop_attr_t *get_loop_attr(morgan_env_t *env, ir_loop *loop) {
109 loop_attr_t l_attr, *res;
113 hash = loop_attr_hash(&l_attr);
114 res = set_find(env->loop_attr_set, &l_attr, sizeof(l_attr), hash);
116 // create new loop_attr if none exists yet
118 l_attr.out_edges = new_set(loop_out_edge_cmp, 1);
119 l_attr.livethrough_unused = bitset_obstack_alloc(&env->phase.obst, get_irg_last_idx(env->irg));
120 res = set_insert(env->loop_attr_set, &l_attr, sizeof(l_attr), hash);
126 static INLINE block_attr_t *get_block_attr(morgan_env_t *env, ir_node *block) {
127 block_attr_t b_attr, *res;
129 b_attr.block = block;
131 hash = block_attr_hash(&b_attr);
132 res = set_find(env->block_attr_set, &b_attr, sizeof(b_attr), hash);
135 b_attr.livethrough_unused = bitset_obstack_alloc(&env->phase.obst, get_irg_last_idx(env->irg));
136 res = set_insert(env->block_attr_set, &b_attr, sizeof(b_attr), hash);
142 static int is_mem_phi(const ir_node *irn, void *data) {
143 // TODO what is this for?
147 //---------------------------------------------------------------------------
150 * Determine edges going out of a loop (= edges that go to a block that is not inside
151 * the loop or one of its subloops)
153 static INLINE void construct_loop_out_edges(ir_node* block, void* e) {
154 morgan_env_t *env = (morgan_env_t*) e;
155 int n_cfgpreds = get_Block_n_cfgpreds(block);
157 ir_loop* loop = get_irn_loop(block);
159 for(i = 0; i < n_cfgpreds; ++i) {
160 ir_node* cfgpred = get_Block_cfgpred(block, i);
161 ir_node* cfgpred_block = get_nodes_block(cfgpred);
162 ir_loop* cfgpred_loop = get_irn_loop(cfgpred_block);
163 loop_attr_t *outedges = get_loop_attr(env, cfgpred_loop);
165 if(cfgpred_loop != loop && get_loop_depth(cfgpred_loop) >= get_loop_depth(loop)) {
166 loop_out_edge_t edge;
169 set_insert(outedges->out_edges, &edge, sizeof(edge), loop_out_edge_hash(&edge));
175 * Construct the livethrough unused information for a block
177 static bitset_t *construct_block_livethrough_unused(morgan_env_t* env, ir_node* block) {
181 block_attr_t *block_attr = get_block_attr(env, block);
184 * This is the first block in a sequence, all variables that are livethrough this block are potential
185 * candidates for livethrough_unused
189 // copy all live-outs into the livethrough_unused set
190 live_foreach(block, li) {
191 if(!live_is_in(li) || !live_is_out(li))
193 if(!arch_irn_consider_in_reg_alloc(env->arch, env->cls, li->irn))
196 node_idx = get_irn_idx(li->irn);
197 bitset_set(block_attr->livethrough_unused, node_idx);
201 * All values that are used within the block are not unused (and therefore not
202 * livethrough_unused)
204 sched_foreach(block, irn) {
205 be_insn_t *insn = be_scan_insn(&env->insn_env, irn);
207 for(i = insn->use_start; i < insn->n_ops; ++i) {
208 const be_operand_t *op = &insn->ops[i];
209 int idx = get_irn_idx(op->irn);
210 bitset_clear(block_attr->livethrough_unused, idx);
214 return block_attr->livethrough_unused;
218 * Debugging help, shows all nodes in a (node-)bitset
220 static void show_nodebitset(ir_graph* irg, bitset_t* bitset) {
223 bitset_foreach(bitset, i) {
224 ir_node* node = get_idx_irn(irg, i);
225 DBG((dbg, DBG_LIVE, "\t%+F\n", node));
229 static bitset_t *construct_loop_livethrough_unused(morgan_env_t *env, ir_loop *loop) {
231 loop_attr_t* loop_attr = get_loop_attr(env, loop);
233 DBG((dbg, DBG_LIVE, "Processing Loop %d\n", loop->loop_nr));
234 assert(get_loop_n_elements(loop) > 0);
235 for(i = 0; i < get_loop_n_elements(loop); ++i) {
236 loop_element elem = get_loop_element(loop, i);
237 switch (*elem.kind) {
239 bitset_t *livethrough_block_unused;
240 assert(is_Block(elem.node));
241 livethrough_block_unused = construct_block_livethrough_unused(env, elem.node);
243 bitset_copy(loop_attr->livethrough_unused, livethrough_block_unused);
245 bitset_and(loop_attr->livethrough_unused, livethrough_block_unused);
250 bitset_t *livethrough_son_unused;
252 livethrough_son_unused = construct_loop_livethrough_unused(env, elem.son);
254 bitset_copy(loop_attr->livethrough_unused, livethrough_son_unused);
256 bitset_and(loop_attr->livethrough_unused, livethrough_son_unused);
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 - unused_spills_possible - env->registers_available;
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.)
331 int pressure_old = pressure;
332 be_liveness_transfer(env->arch, env->cls, irn, live_nodes);
333 pressure = pset_count(live_nodes);
334 DBG((dbg, DBG_PRESSURE, "\tPressure at %+F - before: %d after: %d\n", irn, pressure_old, pressure));
339 * Calculate number of spills from loop_unused_spills_possible that we want to use,
340 * and spill unused livethroughs from the block if we still don't have enough registers
342 spills_needed = max_pressure - env->registers_available;
343 if(spills_needed < 0) {
344 loop_unused_spills_needed = 0;
345 } else if(spills_needed > loop_unused_spills_possible) {
347 int block_unused_spills_needed;
349 loop_unused_spills_needed = loop_unused_spills_possible;
350 block_unused_spills_needed = spills_needed - loop_unused_spills_possible;
351 if(block_unused_spills_needed > block_unused_spills_possible) {
352 block_unused_spills_needed = block_unused_spills_possible;
357 * Spill/Reload unused livethroughs from the block
359 bitset_foreach(block_attr->livethrough_unused, i) {
361 const ir_edge_t *edge;
363 if(spills >= block_unused_spills_needed)
366 to_spill = get_idx_irn(env->irg, i);
367 foreach_block_succ(block, edge) {
368 DBG((dbg, DBG_PRESSURE, "Spilling node %+F around block %+F\n", to_spill, block));
369 be_add_reload_on_edge(env->senv, to_spill, edge->src, edge->pos);
373 loop_unused_spills_needed = spills_needed;
376 del_pset(live_nodes);
378 DBG((dbg, DBG_PRESSURE, "Unused spills for Block %+F needed: %d\n", block, loop_unused_spills_needed));
379 return loop_unused_spills_needed;
383 * Reduce register pressure in a loop
385 * @param unused_spills_possible Number of spills from livethrough_unused variables possible in outer loops
386 * @return Number of spills of livethrough_unused variables needed in outer loops
388 static int reduce_register_pressure_in_loop(morgan_env_t *env, ir_loop *loop, int outer_spills_possible) {
390 loop_attr_t* loop_attr = get_loop_attr(env, loop);
391 int spills_needed = 0;
392 int spills_possible = outer_spills_possible + bitset_popcnt(loop_attr->livethrough_unused);
393 int outer_spills_needed;
395 DBG((dbg, DBG_PRESSURE, "Reducing Pressure in loop %d\n", loop->loop_nr));
396 for(i = 0; i < get_loop_n_elements(loop); ++i) {
397 loop_element elem = get_loop_element(loop, i);
398 switch (*elem.kind) {
401 assert(is_Block(elem.node));
402 needed = reduce_register_pressure_in_block(env, elem.node, spills_possible);
403 assert(needed <= spills_possible);
404 if(needed > spills_needed)
405 spills_needed = needed;
409 int needed = reduce_register_pressure_in_loop(env, elem.son, spills_possible);
410 assert(needed <= spills_possible);
411 if(needed > spills_needed)
412 spills_needed = needed;
421 // calculate number of spills needed in outer loop and spill
422 // unused livethrough nodes around this loop
423 if(spills_needed > outer_spills_possible) {
424 outer_spills_needed = outer_spills_possible;
425 spills_needed -= outer_spills_possible;
427 bitset_foreach(loop_attr->livethrough_unused, i) {
428 loop_out_edge_t *edge;
429 ir_node *to_spill = get_idx_irn(env->irg, i);
431 for(edge = set_first(loop_attr->out_edges); edge != NULL; edge = set_next(loop_attr->out_edges)) {
432 be_add_reload_on_edge(env->senv, to_spill, edge->block, edge->pos);
436 outer_spills_needed = spills_needed;
439 return outer_spills_needed;
442 static void *init_phase_data(phase_t *phase, ir_node *irn, void *old) {
446 void be_spill_morgan(const be_chordal_env_t *chordal_env) {
449 FIRM_DBG_REGISTER(dbg, "ir.be.spillmorgan");
451 env.arch = chordal_env->birg->main_env->arch_env;
452 env.irg = chordal_env->irg;
453 env.cls = chordal_env->cls;
454 env.senv = be_new_spill_env(chordal_env, is_mem_phi, NULL);
455 DEBUG_ONLY(be_set_spill_env_dbg_module(env.senv, dbg);)
456 env.uses = be_begin_uses(env.irg, env.arch, env.cls);
458 phase_init(&env.phase, "spillmorgan", env.irg, PHASE_DEFAULT_GROWTH, init_phase_data);
460 env.registers_available = arch_count_non_ignore_regs(env.arch, env.cls);
462 be_insn_env_init(&env.insn_env, chordal_env->birg, chordal_env->cls, &env.phase.obst);
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 assert(be_verify_schedule(env.irg));
486 be_end_uses(env.uses);
487 be_dump(env.irg, "-spillmorgan", dump_ir_block_graph_sched);
488 del_set(env.loop_attr_set);
489 del_set(env.block_attr_set);
491 // fix the remaining places with too high register pressure with beladies algorithm
492 be_remove_dead_nodes_from_schedule(env.irg);
493 be_liveness(env.irg);
494 be_spill_belady_spill_env(chordal_env, env.senv);
496 be_delete_spill_env(env.senv);
497 phase_free(&env.phase);