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 = ir_nodemap_get(constr_info, &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 ir_nodemap_get(constr_info, &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->u.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->u.last_definition = NULL;
168 mark_irn_visited(block);
169 block_info->u.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 = ir_get_dominance_frontier(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)
301 constr_info *block_info = get_or_set_info(env, block);
303 assert(has_definition(block));
304 assert(!block_info->already_processed && "Block already processed");
306 DBG((dbg, LEVEL_3, "\tprocessing block %+F\n", block));
308 sched_foreach(block, node) {
309 if (is_use(env, node) && !is_Phi(node)) {
310 DBG((dbg, LEVEL_3, "\t...found use %+F\n", node));
313 /* Create a phi if the block is in the dominance frontier. */
314 if (Block_block_visited(block)) {
315 def = insert_dummy_phi(env, block);
318 def = get_def_at_idom(env, block);
322 set_operands(env, node, def);
325 if (is_definition(env, node)) {
326 constr_info *info = get_info(env, node);
327 def = info->u.definition;
328 DBG((dbg, LEVEL_3, "\t...found definition %+F\n", def));
332 block_info->already_processed = true;
333 block_info->u.last_definition = def;
337 * @return Last definition of the given block.
339 static ir_node *search_def_end_of_block(be_ssa_construction_env_t *env,
342 constr_info *block_info = get_or_set_info(env, block);
343 ir_node *last_definition = block_info->u.last_definition;
345 if (last_definition != NULL)
346 return last_definition;
348 if (has_definition(block)) {
349 if (has_use(env, block)) {
350 if (!block_info->already_processed) {
351 process_block(env, block);
355 /* Search the last definition of the block. */
356 sched_foreach_reverse(block, def) {
357 if (is_definition(env, def)) {
358 constr_info *info = get_info(env, def);
359 DBG((dbg, LEVEL_3, "\t...found definition %+F\n", info->u.definition));
360 block_info->u.last_definition = info->u.definition;
365 assert(block_info->u.last_definition && "No definition found");
368 return block_info->u.last_definition;
369 } else if (Block_block_visited(block)) {
370 ir_node *phi = insert_dummy_phi(env, block);
372 block_info->u.last_definition = phi;
376 ir_node *def = get_def_at_idom(env, block);
378 block_info->u.last_definition = def;
385 * Fixes all operands of the given use.
387 static void search_def_at_block(be_ssa_construction_env_t *env, ir_node *use)
389 ir_node *block = get_nodes_block(use);
390 constr_info *block_info = get_or_set_info(env, block);
392 if (block_info->already_processed)
395 if (has_definition(block)) {
396 process_block(env, block);
397 } else if (Block_block_visited(block)) {
398 ir_node *phi = insert_dummy_phi(env, block);
400 set_operands(env, use, phi);
402 ir_node *def = get_def_at_idom(env, block);
404 set_operands(env, use, def);
408 void be_ssa_construction_init(be_ssa_construction_env_t *env, ir_graph *irg)
410 ir_node *sb = get_irg_start_block(irg);
411 int n_blocks = get_Block_dom_max_subtree_pre_num(sb);
413 stat_ev_ctx_push_fobj("bessaconstr", irg);
417 stat_ev_dbl("bessaconstr_n_blocks", n_blocks);
419 memset(env, 0, sizeof(env[0]));
422 env->new_phis = NEW_ARR_F(ir_node*, 0);
423 env->worklist = new_waitq();
424 ir_nodemap_init(&env->infos, irg);
425 obstack_init(&env->obst);
427 assure_irg_properties(env->irg,
428 IR_GRAPH_PROPERTY_CONSISTENT_DOMINANCE_FRONTIERS);
430 ir_reserve_resources(irg, IR_RESOURCE_IRN_VISITED
431 | IR_RESOURCE_BLOCK_VISITED | IR_RESOURCE_IRN_LINK);
433 /* we use the visited flag to indicate blocks in the dominance frontier
434 * and blocks that already have the relevant value at the end calculated */
435 inc_irg_visited(irg);
436 /* We use the block visited flag to indicate blocks in the dominance
437 * frontier of some values (and this potentially needing phis) */
438 inc_irg_block_visited(irg);
441 void be_ssa_construction_destroy(be_ssa_construction_env_t *env)
443 stat_ev_int("bessaconstr_phis", ARR_LEN(env->new_phis));
444 obstack_free(&env->obst, NULL);
445 ir_nodemap_destroy(&env->infos);
446 del_waitq(env->worklist);
447 DEL_ARR_F(env->new_phis);
449 ir_free_resources(env->irg, IR_RESOURCE_IRN_VISITED
450 | IR_RESOURCE_BLOCK_VISITED | IR_RESOURCE_IRN_LINK);
452 stat_ev_tim_pop("bessaconstr_total_time");
453 stat_ev_ctx_pop("bessaconstr");
456 static void determine_phi_req(be_ssa_construction_env_t *env, ir_node *value)
458 const arch_register_req_t *req = arch_get_irn_register_req(value);
459 env->mode = get_irn_mode(value);
460 if (req->width == 1) {
461 env->phi_req = req->cls->class_req;
463 /* construct a new register req... */
464 ir_graph *irg = get_irn_irg(value);
465 struct obstack *obst = be_get_be_obst(irg);
466 arch_register_req_t *new_req = OALLOCZ(obst, arch_register_req_t);
467 new_req->cls = req->cls;
468 new_req->type = req->type & arch_register_req_type_aligned;
469 new_req->width = req->width;
470 env->phi_req = new_req;
474 void be_ssa_construction_add_copy(be_ssa_construction_env_t *env,
479 assert(env->iterated_domfront_calculated == 0);
481 if (env->mode == NULL) {
482 determine_phi_req(env, copy);
484 assert(env->mode == get_irn_mode(copy));
487 block = get_nodes_block(copy);
489 if (!has_definition(block)) {
490 waitq_put(env->worklist, block);
492 introduce_definition(env, copy);
495 void be_ssa_construction_add_copies(be_ssa_construction_env_t *env,
496 ir_node **copies, size_t copies_len)
500 assert(env->iterated_domfront_calculated == 0);
502 if (env->mode == NULL) {
503 determine_phi_req(env, copies[0]);
506 for (i = 0; i < copies_len; ++i) {
507 ir_node *copy = copies[i];
508 ir_node *block = get_nodes_block(copy);
510 assert(env->mode == get_irn_mode(copy));
511 if (!has_definition(block)) {
512 waitq_put(env->worklist, block);
514 introduce_definition(env, copy);
518 void be_ssa_construction_set_ignore_uses(be_ssa_construction_env_t *env,
519 const ir_nodeset_t *ignore_uses)
521 env->ignore_uses = ignore_uses;
524 ir_node **be_ssa_construction_get_new_phis(be_ssa_construction_env_t *env)
526 return env->new_phis;
530 * Fixes all arguments of a newly constructed phi.
532 * @see insert_dummy_phi
534 static void fix_phi_arguments(be_ssa_construction_env_t *env, ir_node *phi)
536 constr_info *info = get_info(env, phi);
537 ir_node *block = get_nodes_block(phi);
539 int n_preds = get_Block_n_cfgpreds(block);
541 DBG((dbg, LEVEL_3, "\tfixing phi arguments %+F\n", phi));
543 for (i = 0; i < n_preds; ++i) {
544 ir_node *op = get_irn_n(phi, i);
546 if (is_definition(env, op) || is_Dummy(op)) {
547 ir_node *pred_block = get_Block_cfgpred_block(block, i);
548 ir_node *pred_def = search_def_end_of_block(env, pred_block);
550 DBG((dbg, LEVEL_1, "\t...%+F(%d) -> %+F\n", phi, i, pred_def));
551 set_irn_n(phi, i, pred_def);
555 info->already_processed = true;
558 void be_ssa_construction_fix_users_array(be_ssa_construction_env_t *env,
559 ir_node **nodes, size_t nodes_len)
562 stat_ev_cnt_decl(uses);
564 be_timer_push(T_SSA_CONSTR);
566 if (!env->iterated_domfront_calculated) {
567 mark_iterated_dominance_frontiers(env);
568 env->iterated_domfront_calculated = 1;
571 DBG((dbg, LEVEL_1, "\tfixing users array\n"));
573 assert(waitq_empty(env->worklist));
577 for (i = 0; i < nodes_len; ++i) {
578 ir_node *value = nodes[i];
579 DBG((dbg, LEVEL_3, "\tfixing users of %+F\n", value));
580 introduce_definition(env, value);
582 foreach_out_edge_safe(value, edge) {
583 ir_node *use = get_edge_src_irn(edge);
585 if (env->ignore_uses != NULL &&
586 ir_nodeset_contains(env->ignore_uses, use))
589 if (is_Anchor(use) || is_End(use))
592 introduce_use(env, use);
596 assert(!waitq_empty(env->worklist));
598 while (!waitq_empty(env->worklist)) {
599 ir_node *use = (ir_node *)waitq_get(env->worklist);
600 constr_info *info = get_info(env, use);
602 if (info->already_processed)
606 fix_phi_arguments(env, use);
609 DBG((dbg, LEVEL_3, "\tsearching def for %+F at %+F\n", use, get_nodes_block(use)));
610 search_def_at_block(env, use);
613 stat_ev_cnt_inc(uses);
616 be_timer_pop(T_SSA_CONSTR);
618 stat_ev_tim_pop("bessaconstr_fix_time");
619 stat_ev_cnt_done(uses, "bessaconstr_uses");
622 void be_ssa_construction_fix_users(be_ssa_construction_env_t *env, ir_node *value)
624 be_ssa_construction_fix_users_array(env, &value, 1);
628 void be_ssa_construction_update_liveness_phis(be_ssa_construction_env_t *env,
633 be_timer_push(T_SSA_CONSTR);
635 n = ARR_LEN(env->new_phis);
636 for (i = 0; i < n; ++i) {
637 ir_node *phi = env->new_phis[i];
638 be_liveness_introduce(lv, phi);
641 be_timer_pop(T_SSA_CONSTR);
644 BE_REGISTER_MODULE_CONSTRUCTOR(be_init_ssaconstr)
645 void be_init_ssaconstr(void)
647 FIRM_DBG_REGISTER(dbg, "firm.be.ssaconstr");