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"
73 DEBUG_ONLY(static firm_dbg_module_t *dbg = NULL;)
75 static ir_node *search_def_end_of_block(be_ssa_construction_env_t *env,
79 bool is_definition : 1;
81 bool already_processed : 1;
83 /* Since we only consider scheduled nodes,
84 * this points to the real definition (e.g. a Proj). */
87 /* Last definition of a block. */
88 ir_node *last_definition;
92 typedef struct constr_info constr_info;
95 * @return Whether the block contains a definition.
97 static bool has_definition(const ir_node *block)
99 return irn_visited(block);
102 static constr_info *get_or_set_info(be_ssa_construction_env_t *env,
105 constr_info *info = ir_nodemap_get(constr_info, &env->infos, node);
107 info = OALLOCZ(&env->obst, constr_info);
108 ir_nodemap_insert(&env->infos, node, info);
113 static constr_info *get_info(const be_ssa_construction_env_t *env,
116 return ir_nodemap_get(constr_info, &env->infos, node);
120 * @return Whether the block contains a use.
122 static inline bool has_use(be_ssa_construction_env_t *env, ir_node *block)
124 constr_info *info = get_or_set_info(env, block);
129 * @return Whether the node is a definition.
131 static bool is_definition(be_ssa_construction_env_t *env, ir_node *node)
133 constr_info *info = get_info(env, node);
134 return info != NULL && info->is_definition;
138 * @return Whether the node is a use.
140 static bool is_use(const be_ssa_construction_env_t *env, ir_node *node)
142 constr_info *info = get_info(env, node);
143 return info != NULL && info->is_use;
147 * Introduces a definition at the corresponding block.
149 static void introduce_definition(be_ssa_construction_env_t *env, ir_node *def)
151 ir_node *block = get_nodes_block(def);
152 constr_info *def_info = get_or_set_info(env, def);
153 ir_node *skip = skip_Proj(def);
154 constr_info *skip_info = get_or_set_info(env, skip);
155 constr_info *block_info = get_or_set_info(env, block);
157 DBG((dbg, LEVEL_2, "\tintroducing definition %+F in %+F\n", def, block));
159 def_info->is_definition = true;
161 skip_info->is_definition = true;
162 skip_info->u.definition = def;
164 // Set the last definition if we only introduce one definition for the block
165 if (has_definition(block)) {
166 assert(!block_info->already_processed);
167 block_info->u.last_definition = NULL;
169 mark_irn_visited(block);
170 block_info->u.last_definition = def;
174 static void introduce_use(be_ssa_construction_env_t *env, ir_node *use)
176 ir_node *block = get_nodes_block(use);
177 constr_info *info = get_or_set_info(env, use);
178 constr_info *block_info = get_or_set_info(env, block);
180 DBG((dbg, LEVEL_2, "\tintroducing use %+F in %+F\n", use, block));
183 block_info->is_use = true;
185 waitq_put(env->worklist, use);
189 * Calculates the iterated dominance frontier of a set of blocks. Marks the
190 * blocks as visited. Sets the link fields of the blocks in the dominance
191 * frontier to the block itself.
193 static void mark_iterated_dominance_frontiers(
194 const be_ssa_construction_env_t *env)
196 stat_ev_cnt_decl(blocks);
197 DBG((dbg, LEVEL_3, "Dominance Frontier:"));
199 while (!waitq_empty(env->worklist)) {
201 ir_node *block = (ir_node*)waitq_get(env->worklist);
202 ir_node **domfront = ir_get_dominance_frontier(block);
203 int domfront_len = ARR_LEN(domfront);
205 for (i = 0; i < domfront_len; ++i) {
206 ir_node *y = domfront[i];
207 if (Block_block_visited(y))
210 if (!irn_visited(y)) {
211 set_irn_link(y, NULL);
212 waitq_put(env->worklist, y);
215 DBG((dbg, LEVEL_3, " %+F", y));
216 mark_Block_block_visited(y);
217 stat_ev_cnt_inc(blocks);
220 stat_ev_tim_pop("bessaconstr_idf_time");
221 stat_ev_cnt_done(blocks, "bessaconstr_idf_blocks");
222 DBG((dbg, LEVEL_3, "\n"));
226 * Inserts a new phi at the given block.
228 * The constructed phi has only Dummy operands,
229 * but can be used as definition for other nodes.
231 * @see fix_phi_arguments
233 static ir_node *insert_dummy_phi(be_ssa_construction_env_t *env, ir_node *block)
235 int i, n_preds = get_Block_n_cfgpreds(block);
236 ir_graph *irg = get_Block_irg(block);
237 ir_node **ins = ALLOCAN(ir_node*, n_preds);
241 DBG((dbg, LEVEL_3, "\t...create phi at block %+F\n", block));
245 dummy = new_r_Dummy(irg, env->mode);
246 for (i = 0; i < n_preds; ++i) {
249 phi = be_new_Phi(block, n_preds, ins, env->mode, env->phi_req);
250 sched_add_after(block, phi);
251 ARR_APP1(ir_node*, env->new_phis, phi);
253 DBG((dbg, LEVEL_2, "\tcreating phi %+F in %+F\n", phi, block));
254 introduce_definition(env, phi);
256 waitq_put(env->worklist, phi);
262 * @return Last definition of the immediate dominator.
264 static ir_node *get_def_at_idom(be_ssa_construction_env_t *env, ir_node *block)
266 ir_node *dom = get_Block_idom(block);
268 DBG((dbg, LEVEL_3, "\t...continue at idom %+F\n", dom));
269 return search_def_end_of_block(env, dom);
273 * Fixes all operands of a use.
275 * If an operand of the use is a (original) definition,
276 * it will be replaced by the given definition.
278 static void set_operands(be_ssa_construction_env_t *env, ir_node *use, ir_node *def)
280 constr_info *info = get_info(env, use);
281 int arity = get_irn_arity(use);
284 for (i = 0; i < arity; ++i) {
285 ir_node *op = get_irn_n(use, i);
287 if (is_definition(env, op)) {
288 DBG((dbg, LEVEL_1, "\t...%+F(%d) -> %+F\n", use, i, def));
289 set_irn_n(use, i, def);
293 info->already_processed = true;
297 * Fixes all uses of the given block.
299 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->u.definition;
329 DBG((dbg, LEVEL_3, "\t...found definition %+F\n", def));
333 block_info->already_processed = true;
334 block_info->u.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->u.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);
356 /* Search the last definition of the block. */
357 sched_foreach_reverse(block, def) {
358 if (is_definition(env, def)) {
359 constr_info *info = get_info(env, def);
360 DBG((dbg, LEVEL_3, "\t...found definition %+F\n", info->u.definition));
361 block_info->u.last_definition = info->u.definition;
366 assert(block_info->u.last_definition && "No definition found");
369 return block_info->u.last_definition;
370 } else if (Block_block_visited(block)) {
371 ir_node *phi = insert_dummy_phi(env, block);
373 block_info->u.last_definition = phi;
377 ir_node *def = get_def_at_idom(env, block);
379 block_info->u.last_definition = def;
386 * Fixes all operands of the given use.
388 static void search_def_at_block(be_ssa_construction_env_t *env, ir_node *use)
390 ir_node *block = get_nodes_block(use);
391 constr_info *block_info = get_or_set_info(env, block);
393 if (block_info->already_processed)
396 if (has_definition(block)) {
397 process_block(env, block);
398 } else if (Block_block_visited(block)) {
399 ir_node *phi = insert_dummy_phi(env, block);
401 set_operands(env, use, phi);
403 ir_node *def = get_def_at_idom(env, block);
405 set_operands(env, use, def);
409 void be_ssa_construction_init(be_ssa_construction_env_t *env, ir_graph *irg)
411 ir_node *sb = get_irg_start_block(irg);
412 int n_blocks = get_Block_dom_max_subtree_pre_num(sb);
414 stat_ev_ctx_push_fmt("bessaconstr", "%+F", irg);
418 stat_ev_dbl("bessaconstr_n_blocks", n_blocks);
420 memset(env, 0, sizeof(env[0]));
423 env->new_phis = NEW_ARR_F(ir_node*, 0);
424 env->worklist = new_waitq();
425 ir_nodemap_init(&env->infos, irg);
426 obstack_init(&env->obst);
428 assure_irg_properties(env->irg,
429 IR_GRAPH_PROPERTY_CONSISTENT_DOMINANCE_FRONTIERS);
431 ir_reserve_resources(irg, IR_RESOURCE_IRN_VISITED
432 | IR_RESOURCE_BLOCK_VISITED | IR_RESOURCE_IRN_LINK);
434 /* we use the visited flag to indicate blocks in the dominance frontier
435 * and blocks that already have the relevant value at the end calculated */
436 inc_irg_visited(irg);
437 /* We use the block visited flag to indicate blocks in the dominance
438 * frontier of some values (and this potentially needing phis) */
439 inc_irg_block_visited(irg);
442 void be_ssa_construction_destroy(be_ssa_construction_env_t *env)
444 stat_ev_int("bessaconstr_phis", ARR_LEN(env->new_phis));
445 obstack_free(&env->obst, NULL);
446 ir_nodemap_destroy(&env->infos);
447 del_waitq(env->worklist);
448 DEL_ARR_F(env->new_phis);
450 ir_free_resources(env->irg, IR_RESOURCE_IRN_VISITED
451 | IR_RESOURCE_BLOCK_VISITED | IR_RESOURCE_IRN_LINK);
453 stat_ev_tim_pop("bessaconstr_total_time");
454 stat_ev_ctx_pop("bessaconstr");
457 static void determine_phi_req(be_ssa_construction_env_t *env, ir_node *value)
459 const arch_register_req_t *req = arch_get_irn_register_req(value);
460 env->mode = get_irn_mode(value);
461 if (req->width == 1) {
462 env->phi_req = req->cls->class_req;
464 /* construct a new register req... */
465 ir_graph *irg = get_irn_irg(value);
466 struct obstack *obst = be_get_be_obst(irg);
467 arch_register_req_t *new_req = OALLOCZ(obst, arch_register_req_t);
468 new_req->cls = req->cls;
469 new_req->type = req->type & arch_register_req_type_aligned;
470 new_req->width = req->width;
471 env->phi_req = new_req;
475 void be_ssa_construction_add_copy(be_ssa_construction_env_t *env,
480 assert(env->iterated_domfront_calculated == 0);
482 if (env->mode == NULL) {
483 determine_phi_req(env, copy);
485 assert(env->mode == get_irn_mode(copy));
488 block = get_nodes_block(copy);
490 if (!has_definition(block)) {
491 waitq_put(env->worklist, block);
493 introduce_definition(env, copy);
496 void be_ssa_construction_add_copies(be_ssa_construction_env_t *env,
497 ir_node **copies, size_t copies_len)
501 assert(env->iterated_domfront_calculated == 0);
503 if (env->mode == NULL) {
504 determine_phi_req(env, copies[0]);
507 for (i = 0; i < copies_len; ++i) {
508 ir_node *copy = copies[i];
509 ir_node *block = get_nodes_block(copy);
511 assert(env->mode == get_irn_mode(copy));
512 if (!has_definition(block)) {
513 waitq_put(env->worklist, block);
515 introduce_definition(env, copy);
519 void be_ssa_construction_set_ignore_uses(be_ssa_construction_env_t *env,
520 const ir_nodeset_t *ignore_uses)
522 env->ignore_uses = ignore_uses;
525 ir_node **be_ssa_construction_get_new_phis(be_ssa_construction_env_t *env)
527 return env->new_phis;
531 * Fixes all arguments of a newly constructed phi.
533 * @see insert_dummy_phi
535 static void fix_phi_arguments(be_ssa_construction_env_t *env, ir_node *phi)
537 constr_info *info = get_info(env, phi);
538 ir_node *block = get_nodes_block(phi);
540 int n_preds = get_Block_n_cfgpreds(block);
542 DBG((dbg, LEVEL_3, "\tfixing phi arguments %+F\n", phi));
544 for (i = 0; i < n_preds; ++i) {
545 ir_node *op = get_irn_n(phi, i);
547 if (is_definition(env, op) || is_Dummy(op)) {
548 ir_node *pred_block = get_Block_cfgpred_block(block, i);
549 ir_node *pred_def = search_def_end_of_block(env, pred_block);
551 DBG((dbg, LEVEL_1, "\t...%+F(%d) -> %+F\n", phi, i, pred_def));
552 set_irn_n(phi, i, pred_def);
556 info->already_processed = true;
559 void be_ssa_construction_fix_users_array(be_ssa_construction_env_t *env,
560 ir_node **nodes, size_t nodes_len)
563 stat_ev_cnt_decl(uses);
565 be_timer_push(T_SSA_CONSTR);
567 if (!env->iterated_domfront_calculated) {
568 mark_iterated_dominance_frontiers(env);
569 env->iterated_domfront_calculated = 1;
572 DBG((dbg, LEVEL_1, "\tfixing users array\n"));
574 assert(waitq_empty(env->worklist));
578 for (i = 0; i < nodes_len; ++i) {
579 ir_node *value = nodes[i];
580 DBG((dbg, LEVEL_3, "\tfixing users of %+F\n", value));
581 introduce_definition(env, value);
583 foreach_out_edge_safe(value, edge) {
584 ir_node *use = get_edge_src_irn(edge);
586 if (env->ignore_uses != NULL &&
587 ir_nodeset_contains(env->ignore_uses, use))
590 if (is_Anchor(use) || is_End(use))
593 introduce_use(env, use);
597 assert(!waitq_empty(env->worklist));
599 while (!waitq_empty(env->worklist)) {
600 ir_node *use = (ir_node *)waitq_get(env->worklist);
601 constr_info *info = get_info(env, use);
603 if (info->already_processed)
607 fix_phi_arguments(env, use);
610 DBG((dbg, LEVEL_3, "\tsearching def for %+F at %+F\n", use, get_nodes_block(use)));
611 search_def_at_block(env, use);
614 stat_ev_cnt_inc(uses);
617 be_timer_pop(T_SSA_CONSTR);
619 stat_ev_tim_pop("bessaconstr_fix_time");
620 stat_ev_cnt_done(uses, "bessaconstr_uses");
623 void be_ssa_construction_fix_users(be_ssa_construction_env_t *env, ir_node *value)
625 be_ssa_construction_fix_users_array(env, &value, 1);
629 void be_ssa_construction_update_liveness_phis(be_ssa_construction_env_t *env,
634 be_timer_push(T_SSA_CONSTR);
636 n = ARR_LEN(env->new_phis);
637 for (i = 0; i < n; ++i) {
638 ir_node *phi = env->new_phis[i];
639 be_liveness_introduce(lv, phi);
642 be_timer_pop(T_SSA_CONSTR);
645 BE_REGISTER_MODULE_CONSTRUCTOR(be_init_ssaconstr)
646 void be_init_ssaconstr(void)
648 FIRM_DBG_REGISTER(dbg, "firm.be.ssaconstr");