2 * Copyright (C) 1995-2008 University of Karlsruhe. All right reserved.
4 * This file is part of libFirm.
6 * This file may be distributed and/or modified under the terms of the
7 * GNU General Public License version 2 as published by the Free Software
8 * Foundation and appearing in the file LICENSE.GPL included in the
9 * packaging of this file.
11 * Licensees holding valid libFirm Professional Edition licenses may use
12 * this file in accordance with the libFirm Commercial License.
13 * Agreement provided with the Software.
15 * This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
16 * WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR
22 * @brief SSA construction for a set of nodes
23 * @author Sebastian Hack, Daniel Grund, Matthias Braun, Christian Wuerdig,
27 * The problem: Given a value and a set of "copies" that are known to
28 * represent the same abstract value, rewire all usages of the original value
29 * to their closest copy while introducing phis as necessary.
31 * Algorithm: Mark all blocks in the iterated dominance frontiers of the value
32 * and its copies. Link the copies ordered by dominance to the blocks. Then
33 * we search for each use all definitions in the current block, if none is
34 * found, then we search one in the immediate dominator. If we are in a block
35 * of the dominance frontier, create a phi and do the same search for all
38 * A copy in this context means, that you want to introduce several new
39 * abstract values (in Firm: nodes) for which you know, that they
40 * represent the same concrete value. This is the case if you
46 * This function reroutes all uses of the original value to the copies in the
47 * corresponding dominance subtrees and creates Phi functions where necessary.
51 /* statev in this file is extensive, so only enable if needed */
52 #define DISABLE_STATEV
54 #include "bessaconstr.h"
57 #include "beintlive_t.h"
67 #include "irnodeset.h"
70 #include "iredges_t.h"
72 DEBUG_ONLY(static firm_dbg_module_t *dbg = NULL;)
74 static ir_node *search_def_end_of_block(be_ssa_construction_env_t *env,
78 bool is_definition : 1;
80 bool already_processed : 1;
82 /* Since we only consider scheduled nodes,
83 * this points to the real definition (e.g. a Proj). */
86 /* Last definition of a block. */
87 ir_node *last_definition;
91 typedef struct constr_info constr_info;
94 * @return Whether the block contains a definition.
96 static bool has_definition(const ir_node *block)
98 return irn_visited(block);
101 static constr_info *get_or_set_info(be_ssa_construction_env_t *env,
104 constr_info *info = (constr_info*)ir_nodemap_get(&env->infos, node);
106 info = OALLOCZ(&env->obst, constr_info);
107 ir_nodemap_insert(&env->infos, node, info);
112 static constr_info *get_info(const be_ssa_construction_env_t *env,
115 return (constr_info*)ir_nodemap_get(&env->infos, node);
119 * @return Whether the block contains a use.
121 static inline bool has_use(be_ssa_construction_env_t *env, ir_node *block)
123 constr_info *info = get_or_set_info(env, block);
128 * @return Whether the node is a definition.
130 static bool is_definition(be_ssa_construction_env_t *env, ir_node *node)
132 constr_info *info = get_info(env, node);
133 return info != NULL && info->is_definition;
137 * @return Whether the node is a use.
139 static bool is_use(const be_ssa_construction_env_t *env, ir_node *node)
141 constr_info *info = get_info(env, node);
142 return info != NULL && info->is_use;
146 * Introduces a definition at the corresponding block.
148 static void introduce_definition(be_ssa_construction_env_t *env, ir_node *def)
150 ir_node *block = get_nodes_block(def);
151 constr_info *def_info = get_or_set_info(env, def);
152 ir_node *skip = skip_Proj(def);
153 constr_info *skip_info = get_or_set_info(env, skip);
154 constr_info *block_info = get_or_set_info(env, block);
156 DBG((dbg, LEVEL_2, "\tintroducing definition %+F in %+F\n", def, block));
158 def_info->is_definition = true;
160 skip_info->is_definition = true;
161 skip_info->definition = def;
163 // Set the last definition if we only introduce one definition for the block
164 if (has_definition(block)) {
165 assert(!block_info->already_processed);
166 block_info->last_definition = NULL;
168 mark_irn_visited(block);
169 block_info->last_definition = def;
173 static void introduce_use(be_ssa_construction_env_t *env, ir_node *use)
175 ir_node *block = get_nodes_block(use);
176 constr_info *info = get_or_set_info(env, use);
177 constr_info *block_info = get_or_set_info(env, block);
179 DBG((dbg, LEVEL_2, "\tintroducing use %+F in %+F\n", use, block));
182 block_info->is_use = true;
184 waitq_put(env->worklist, use);
188 * Calculates the iterated dominance frontier of a set of blocks. Marks the
189 * blocks as visited. Sets the link fields of the blocks in the dominance
190 * frontier to the block itself.
192 static void mark_iterated_dominance_frontiers(
193 const be_ssa_construction_env_t *env)
195 stat_ev_cnt_decl(blocks);
196 DBG((dbg, LEVEL_3, "Dominance Frontier:"));
198 while (!waitq_empty(env->worklist)) {
200 ir_node *block = (ir_node*)waitq_get(env->worklist);
201 ir_node **domfront = be_get_dominance_frontier(env->domfronts, block);
202 int domfront_len = ARR_LEN(domfront);
204 for (i = 0; i < domfront_len; ++i) {
205 ir_node *y = domfront[i];
206 if (Block_block_visited(y))
209 if (!irn_visited(y)) {
210 set_irn_link(y, NULL);
211 waitq_put(env->worklist, y);
214 DBG((dbg, LEVEL_3, " %+F", y));
215 mark_Block_block_visited(y);
216 stat_ev_cnt_inc(blocks);
219 stat_ev_tim_pop("bessaconstr_idf_time");
220 stat_ev_cnt_done(blocks, "bessaconstr_idf_blocks");
221 DBG((dbg, LEVEL_3, "\n"));
225 * Inserts a new phi at the given block.
227 * The constructed phi has only Dummy operands,
228 * but can be used as definition for other nodes.
230 * @see fix_phi_arguments
232 static ir_node *insert_dummy_phi(be_ssa_construction_env_t *env, ir_node *block)
234 int i, n_preds = get_Block_n_cfgpreds(block);
235 ir_graph *irg = get_Block_irg(block);
236 ir_node **ins = ALLOCAN(ir_node*, n_preds);
240 DBG((dbg, LEVEL_3, "\t...create phi at block %+F\n", block));
244 dummy = new_r_Dummy(irg, env->mode);
245 for (i = 0; i < n_preds; ++i) {
248 phi = be_new_Phi(block, n_preds, ins, env->mode, env->phi_req);
249 sched_add_after(block, phi);
250 ARR_APP1(ir_node*, env->new_phis, phi);
252 DBG((dbg, LEVEL_2, "\tcreating phi %+F in %+F\n", phi, block));
253 introduce_definition(env, phi);
255 waitq_put(env->worklist, phi);
261 * @return Last definition of the immediate dominator.
263 static ir_node *get_def_at_idom(be_ssa_construction_env_t *env, ir_node *block)
265 ir_node *dom = get_Block_idom(block);
267 DBG((dbg, LEVEL_3, "\t...continue at idom %+F\n", dom));
268 return search_def_end_of_block(env, dom);
272 * Fixes all operands of a use.
274 * If an operand of the use is a (original) definition,
275 * it will be replaced by the given definition.
277 static void set_operands(be_ssa_construction_env_t *env, ir_node *use, ir_node *def)
279 constr_info *info = get_info(env, use);
280 int arity = get_irn_arity(use);
283 for (i = 0; i < arity; ++i) {
284 ir_node *op = get_irn_n(use, i);
286 if (is_definition(env, op)) {
287 DBG((dbg, LEVEL_1, "\t...%+F(%d) -> %+F\n", use, i, def));
288 set_irn_n(use, i, def);
292 info->already_processed = true;
296 * Fixes all uses of the given block.
298 static void process_block(be_ssa_construction_env_t *env, ir_node *block)
302 constr_info *block_info = get_or_set_info(env, block);
304 assert(has_definition(block));
305 assert(!block_info->already_processed && "Block already processed");
307 DBG((dbg, LEVEL_3, "\tprocessing block %+F\n", block));
309 sched_foreach(block, node) {
310 if (is_use(env, node) && !is_Phi(node)) {
311 DBG((dbg, LEVEL_3, "\t...found use %+F\n", node));
314 /* Create a phi if the block is in the dominance frontier. */
315 if (Block_block_visited(block)) {
316 def = insert_dummy_phi(env, block);
319 def = get_def_at_idom(env, block);
323 set_operands(env, node, def);
326 if (is_definition(env, node)) {
327 constr_info *info = get_info(env, node);
328 def = info->definition;
329 DBG((dbg, LEVEL_3, "\t...found definition %+F\n", def));
333 block_info->already_processed = true;
334 block_info->last_definition = def;
338 * @return Last definition of the given block.
340 static ir_node *search_def_end_of_block(be_ssa_construction_env_t *env,
343 constr_info *block_info = get_or_set_info(env, block);
344 ir_node *last_definition = block_info->last_definition;
346 if (last_definition != NULL)
347 return last_definition;
349 if (has_definition(block)) {
350 if (has_use(env, block)) {
351 if (!block_info->already_processed) {
352 process_block(env, block);
358 /* Search the last definition of the block. */
359 sched_foreach_reverse(block, def) {
360 if (is_definition(env, def)) {
361 constr_info *info = get_info(env, def);
362 def = info->definition;
363 DBG((dbg, LEVEL_3, "\t...found definition %+F\n", def));
369 assert(def && "No definition found");
371 block_info->last_definition = def;
374 return block_info->last_definition;
375 } else if (Block_block_visited(block)) {
376 ir_node *phi = insert_dummy_phi(env, block);
378 block_info->last_definition = phi;
382 ir_node *def = get_def_at_idom(env, block);
384 block_info->last_definition = def;
391 * Fixes all operands of the given use.
393 static void search_def_at_block(be_ssa_construction_env_t *env, ir_node *use)
395 ir_node *block = get_nodes_block(use);
396 constr_info *block_info = get_or_set_info(env, block);
398 if (block_info->already_processed)
401 if (has_definition(block)) {
402 process_block(env, block);
403 } else if (Block_block_visited(block)) {
404 ir_node *phi = insert_dummy_phi(env, block);
406 set_operands(env, use, phi);
408 ir_node *def = get_def_at_idom(env, block);
410 set_operands(env, use, def);
414 void be_ssa_construction_init(be_ssa_construction_env_t *env, ir_graph *irg)
416 ir_node *sb = get_irg_start_block(irg);
417 int n_blocks = get_Block_dom_max_subtree_pre_num(sb);
419 stat_ev_ctx_push_fobj("bessaconstr", irg);
423 stat_ev_dbl("bessaconstr_n_blocks", n_blocks);
425 memset(env, 0, sizeof(env[0]));
426 be_assure_dom_front(irg);
429 env->domfronts = be_get_irg_dom_front(irg);
430 env->new_phis = NEW_ARR_F(ir_node*, 0);
431 env->worklist = new_waitq();
432 ir_nodemap_init(&env->infos, irg);
433 obstack_init(&env->obst);
435 ir_reserve_resources(irg, IR_RESOURCE_IRN_VISITED
436 | IR_RESOURCE_BLOCK_VISITED | IR_RESOURCE_IRN_LINK);
438 /* we use the visited flag to indicate blocks in the dominance frontier
439 * and blocks that already have the relevant value at the end calculated */
440 inc_irg_visited(irg);
441 /* We use the block visited flag to indicate blocks in the dominance
442 * frontier of some values (and this potentially needing phis) */
443 inc_irg_block_visited(irg);
446 void be_ssa_construction_destroy(be_ssa_construction_env_t *env)
448 stat_ev_int("bessaconstr_phis", ARR_LEN(env->new_phis));
449 obstack_free(&env->obst, NULL);
450 ir_nodemap_destroy(&env->infos);
451 del_waitq(env->worklist);
452 DEL_ARR_F(env->new_phis);
454 ir_free_resources(env->irg, IR_RESOURCE_IRN_VISITED
455 | IR_RESOURCE_BLOCK_VISITED | IR_RESOURCE_IRN_LINK);
457 stat_ev_tim_pop("bessaconstr_total_time");
458 stat_ev_ctx_pop("bessaconstr");
461 static void determine_phi_req(be_ssa_construction_env_t *env, ir_node *value)
463 const arch_register_req_t *req = arch_get_irn_register_req(value);
464 env->mode = get_irn_mode(value);
465 if (req->width == 1) {
466 env->phi_req = req->cls->class_req;
468 /* construct a new register req... */
469 ir_graph *irg = get_irn_irg(value);
470 struct obstack *obst = be_get_be_obst(irg);
471 arch_register_req_t *new_req = OALLOCZ(obst, arch_register_req_t);
472 new_req->cls = req->cls;
473 new_req->type = req->type & arch_register_req_type_aligned;
474 new_req->width = req->width;
475 env->phi_req = new_req;
479 void be_ssa_construction_add_copy(be_ssa_construction_env_t *env,
484 assert(env->iterated_domfront_calculated == 0);
486 if (env->mode == NULL) {
487 determine_phi_req(env, copy);
489 assert(env->mode == get_irn_mode(copy));
492 block = get_nodes_block(copy);
494 if (!has_definition(block)) {
495 waitq_put(env->worklist, block);
497 introduce_definition(env, copy);
500 void be_ssa_construction_add_copies(be_ssa_construction_env_t *env,
501 ir_node **copies, size_t copies_len)
505 assert(env->iterated_domfront_calculated == 0);
507 if (env->mode == NULL) {
508 determine_phi_req(env, copies[0]);
511 for (i = 0; i < copies_len; ++i) {
512 ir_node *copy = copies[i];
513 ir_node *block = get_nodes_block(copy);
515 assert(env->mode == get_irn_mode(copy));
516 if (!has_definition(block)) {
517 waitq_put(env->worklist, block);
519 introduce_definition(env, copy);
523 void be_ssa_construction_set_ignore_uses(be_ssa_construction_env_t *env,
524 const ir_nodeset_t *ignore_uses)
526 env->ignore_uses = ignore_uses;
529 ir_node **be_ssa_construction_get_new_phis(be_ssa_construction_env_t *env)
531 return env->new_phis;
535 * Fixes all arguments of a newly constructed phi.
537 * @see insert_dummy_phi
539 static void fix_phi_arguments(be_ssa_construction_env_t *env, ir_node *phi)
541 constr_info *info = get_info(env, phi);
542 ir_node *block = get_nodes_block(phi);
544 int n_preds = get_Block_n_cfgpreds(block);
546 DBG((dbg, LEVEL_3, "\tfixing phi arguments %+F\n", phi));
548 for (i = 0; i < n_preds; ++i) {
549 ir_node *op = get_irn_n(phi, i);
551 if (is_definition(env, op) || is_Dummy(op)) {
552 ir_node *pred_block = get_Block_cfgpred_block(block, i);
553 ir_node *pred_def = search_def_end_of_block(env, pred_block);
555 DBG((dbg, LEVEL_1, "\t...%+F(%d) -> %+F\n", phi, i, pred_def));
556 set_irn_n(phi, i, pred_def);
560 info->already_processed = true;
563 void be_ssa_construction_fix_users_array(be_ssa_construction_env_t *env,
564 ir_node **nodes, size_t nodes_len)
567 stat_ev_cnt_decl(uses);
569 be_timer_push(T_SSA_CONSTR);
571 if (!env->iterated_domfront_calculated) {
572 mark_iterated_dominance_frontiers(env);
573 env->iterated_domfront_calculated = 1;
576 DBG((dbg, LEVEL_1, "\tfixing users array\n"));
578 assert(waitq_empty(env->worklist));
582 for (i = 0; i < nodes_len; ++i) {
583 const ir_edge_t *edge, *next;
584 ir_node *value = nodes[i];
585 DBG((dbg, LEVEL_3, "\tfixing users of %+F\n", value));
586 introduce_definition(env, value);
588 foreach_out_edge_safe(value, edge, next) {
589 ir_node *use = get_edge_src_irn(edge);
591 if (env->ignore_uses != NULL &&
592 ir_nodeset_contains(env->ignore_uses, use))
595 if (is_Anchor(use) || is_End(use))
598 introduce_use(env, use);
602 assert(!waitq_empty(env->worklist));
604 while (!waitq_empty(env->worklist)) {
605 ir_node *use = (ir_node *)waitq_get(env->worklist);
606 constr_info *info = get_info(env, use);
608 if (info->already_processed)
612 fix_phi_arguments(env, use);
615 DBG((dbg, LEVEL_3, "\tsearching def for %+F at %+F\n", use, get_nodes_block(use)));
616 search_def_at_block(env, use);
619 stat_ev_cnt_inc(uses);
622 be_timer_pop(T_SSA_CONSTR);
624 stat_ev_tim_pop("bessaconstr_fix_time");
625 stat_ev_cnt_done(uses, "bessaconstr_uses");
628 void be_ssa_construction_fix_users(be_ssa_construction_env_t *env, ir_node *value)
630 be_ssa_construction_fix_users_array(env, &value, 1);
634 void be_ssa_construction_update_liveness_phis(be_ssa_construction_env_t *env,
639 be_timer_push(T_SSA_CONSTR);
641 n = ARR_LEN(env->new_phis);
642 for (i = 0; i < n; ++i) {
643 ir_node *phi = env->new_phis[i];
644 be_liveness_introduce(lv, phi);
647 be_timer_pop(T_SSA_CONSTR);
650 BE_REGISTER_MODULE_CONSTRUCTOR(be_init_ssaconstr)
651 void be_init_ssaconstr(void)
653 FIRM_DBG_REGISTER(dbg, "firm.be.ssaconstr");