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 it's 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.
53 /* statev in this file is extensive, so only enable if needed */
54 #define DISABLE_STATEV
56 #include "bessaconstr.h"
58 #include "besched_t.h"
59 #include "beintlive_t.h"
70 #include "iredges_t.h"
72 DEBUG_ONLY(static firm_dbg_module_t *dbg = NULL;)
75 * Calculates the iterated dominance frontier of a set of blocks. Marks the
76 * blocks as visited. Sets the link fields of the blocks in the dominance
77 * frontier to the block itself.
80 void mark_iterated_dominance_frontiers(const be_ssa_construction_env_t *env)
82 stat_ev_cnt_decl(blocks);
83 DBG((dbg, LEVEL_3, "Dominance Frontier:"));
85 while (!waitq_empty(env->worklist)) {
87 ir_node *block = waitq_get(env->worklist);
88 ir_node **domfront = be_get_dominance_frontier(env->domfronts, block);
89 int domfront_len = ARR_LEN(domfront);
91 for (i = 0; i < domfront_len; ++i) {
92 ir_node *y = domfront[i];
93 if (Block_block_visited(y))
96 if (!irn_visited(y)) {
97 set_irn_link(y, NULL);
98 waitq_put(env->worklist, y);
101 DBG((dbg, LEVEL_3, " %+F", y));
102 mark_Block_block_visited(y);
103 stat_ev_cnt_inc(blocks);
106 stat_ev_tim_pop("bessaconstr_idf_time");
107 stat_ev_cnt_done(blocks, "bessaconstr_idf_blocks");
108 DBG((dbg, LEVEL_3, "\n"));
112 ir_node *search_def_end_of_block(be_ssa_construction_env_t *env,
116 ir_node *create_phi(be_ssa_construction_env_t *env, ir_node *block,
119 int i, n_preds = get_Block_n_cfgpreds(block);
120 ir_graph *irg = get_irn_irg(block);
122 ir_node **ins = alloca(n_preds * sizeof(ins[0]));
126 for(i = 0; i < n_preds; ++i) {
127 ins[i] = new_r_Unknown(irg, env->mode);
129 phi = new_r_Phi(irg, block, n_preds, ins, env->mode);
130 if(env->new_phis != NULL) {
131 ARR_APP1(ir_node*, env->new_phis, phi);
134 if(env->mode != mode_M) {
135 sched_add_after(block, phi);
138 DBG((dbg, LEVEL_2, "\tcreating phi %+F in %+F\n", phi, block));
139 set_irn_link(link_with, phi);
140 mark_irn_visited(block);
142 for(i = 0; i < n_preds; ++i) {
143 ir_node *pred_block = get_Block_cfgpred_block(block, i);
144 ir_node *pred_def = search_def_end_of_block(env, pred_block);
146 set_irn_n(phi, i, pred_def);
153 ir_node *get_def_at_idom(be_ssa_construction_env_t *env, ir_node *block)
155 ir_node *dom = get_Block_idom(block);
157 return search_def_end_of_block(env, dom);
161 ir_node *search_def_end_of_block(be_ssa_construction_env_t *env, ir_node *block)
163 if(irn_visited(block)) {
164 assert(get_irn_link(block) != NULL);
165 return get_irn_link(block);
166 } else if(Block_block_visited(block)) {
167 return create_phi(env, block, block);
169 ir_node *def = get_def_at_idom(env, block);
170 mark_irn_visited(block);
171 set_irn_link(block, def);
177 ir_node *search_def(be_ssa_construction_env_t *env, ir_node *at)
179 ir_node *block = get_nodes_block(at);
183 DBG((dbg, LEVEL_3, "\t...searching def at %+F\n", at));
185 /* no defs in the current block we can do the normal searching */
186 if(!irn_visited(block) && !Block_block_visited(block)) {
187 DBG((dbg, LEVEL_3, "\t...continue at idom\n"));
188 return get_def_at_idom(env, block);
191 /* there are defs in the current block, walk the linked list to find
192 the one immediately dominating us
195 def = get_irn_link(node);
197 if(!value_dominates(at, def)) {
198 DBG((dbg, LEVEL_3, "\t...found dominating def %+F\n", def));
203 def = get_irn_link(node);
206 /* block in dominance frontier? create a phi then */
207 if(Block_block_visited(block)) {
208 DBG((dbg, LEVEL_3, "\t...create phi at block %+F\n", block));
209 assert(!is_Phi(node));
210 return create_phi(env, block, node);
213 DBG((dbg, LEVEL_3, "\t...continue at idom (after checking block)\n"));
214 return get_def_at_idom(env, block);
218 * Adds a definition into the link field of the block. The definitions are
219 * sorted by dominance. A non-visited block means no definition has been
223 void introduce_def_at_block(ir_node *block, ir_node *def)
225 if(irn_visited(block)) {
226 ir_node *node = block;
227 ir_node *current_def;
230 current_def = get_irn_link(node);
231 if(current_def == def) {
232 /* already in block */
235 if(current_def == NULL)
237 if(value_dominates(current_def, def))
242 set_irn_link(node, def);
243 set_irn_link(def, current_def);
245 set_irn_link(block, def);
246 set_irn_link(def, NULL);
247 mark_irn_visited(block);
251 void be_ssa_construction_init(be_ssa_construction_env_t *env, be_irg_t *birg)
253 ir_graph *irg = be_get_birg_irg(birg);
254 ir_node *sb = get_irg_start_block(irg);
255 int n_blocks = get_Block_dom_max_subtree_pre_num(sb);
257 stat_ev_ctx_push_fobj("bessaconstr", irg);
261 stat_ev_dbl("bessaconstr_n_blocks", n_blocks);
263 memset(env, 0, sizeof(env[0]));
264 be_assure_dom_front(birg);
267 env->domfronts = be_get_birg_dom_front(birg);
268 env->new_phis = NEW_ARR_F(ir_node*, 0);
269 env->worklist = new_waitq();
271 ir_reserve_resources(irg, IR_RESOURCE_IRN_VISITED
272 | IR_RESOURCE_BLOCK_VISITED | IR_RESOURCE_IRN_LINK);
274 /* we use the visited flag to indicate blocks in the dominance frontier
275 * and blocks that already have the relevant value at the end calculated */
276 inc_irg_visited(irg);
277 /* We use the block visited flag to indicate blocks in the dominance
278 * frontier of some values (and this potentially needing phis) */
279 inc_irg_block_visited(irg);
282 void be_ssa_construction_destroy(be_ssa_construction_env_t *env)
284 stat_ev_int("bessaconstr_phis", ARR_LEN(env->new_phis));
285 del_waitq(env->worklist);
286 DEL_ARR_F(env->new_phis);
288 ir_free_resources(env->irg, IR_RESOURCE_IRN_VISITED
289 | IR_RESOURCE_BLOCK_VISITED | IR_RESOURCE_IRN_LINK);
291 stat_ev_tim_pop("bessaconstr_total_time");
292 stat_ev_ctx_pop("bessaconstr");
295 void be_ssa_construction_add_copy(be_ssa_construction_env_t *env,
300 assert(env->iterated_domfront_calculated == 0);
302 if(env->mode == NULL) {
303 env->mode = get_irn_mode(copy);
305 assert(env->mode == get_irn_mode(copy));
308 block = get_nodes_block(copy);
310 if(!irn_visited(block)) {
311 waitq_put(env->worklist, block);
313 introduce_def_at_block(block, copy);
316 void be_ssa_construction_add_copies(be_ssa_construction_env_t *env,
317 ir_node **copies, size_t copies_len)
321 assert(env->iterated_domfront_calculated == 0);
323 if(env->mode == NULL) {
324 env->mode = get_irn_mode(copies[0]);
327 for(i = 0; i < copies_len; ++i) {
328 ir_node *copy = copies[i];
329 ir_node *block = get_nodes_block(copy);
331 assert(env->mode == get_irn_mode(copy));
332 if(!irn_visited(block)) {
333 waitq_put(env->worklist, block);
335 introduce_def_at_block(block, copy);
339 void be_ssa_construction_set_ignore_uses(be_ssa_construction_env_t *env,
340 const ir_nodeset_t *ignore_uses)
342 env->ignore_uses = ignore_uses;
345 ir_node **be_ssa_construction_get_new_phis(be_ssa_construction_env_t *env)
347 return env->new_phis;
350 void be_ssa_construction_fix_users_array(be_ssa_construction_env_t *env,
351 ir_node **nodes, size_t nodes_len)
353 const ir_edge_t *edge, *next;
355 stat_ev_cnt_decl(uses);
357 BE_TIMER_PUSH(t_ssa_constr);
359 if(!env->iterated_domfront_calculated) {
360 mark_iterated_dominance_frontiers(env);
361 env->iterated_domfront_calculated = 1;
365 for(i = 0; i < nodes_len; ++i) {
366 ir_node *value = nodes[i];
369 * Search the valid def for each use and set it.
371 foreach_out_edge_safe(value, edge, next) {
372 ir_node *use = get_edge_src_irn(edge);
374 int pos = get_edge_src_pos(edge);
377 if(env->ignore_uses != NULL &&
378 ir_nodeset_contains(env->ignore_uses, use))
384 ir_node *block = get_nodes_block(use);
385 ir_node *predblock = get_Block_cfgpred_block(block, pos);
386 at = sched_last(predblock);
389 def = search_def(env, at);
392 panic("no definition found for %+F at position %d", use, pos);
395 DBG((dbg, LEVEL_2, "\t%+F(%d) -> %+F\n", use, pos, def));
396 set_irn_n(use, pos, def);
397 stat_ev_cnt_inc(uses);
400 BE_TIMER_POP(t_ssa_constr);
402 stat_ev_tim_pop("bessaconstr_fix_time");
403 stat_ev_cnt_done(uses, "bessaconstr_uses");
406 void be_ssa_construction_fix_users(be_ssa_construction_env_t *env, ir_node *value)
408 be_ssa_construction_fix_users_array(env, &value, 1);
412 void be_ssa_construction_update_liveness_phis(be_ssa_construction_env_t *env,
417 BE_TIMER_PUSH(t_ssa_constr);
419 n = ARR_LEN(env->new_phis);
420 for(i = 0; i < n; ++i) {
421 ir_node *phi = env->new_phis[i];
422 be_liveness_introduce(lv, phi);
425 BE_TIMER_POP(t_ssa_constr);
428 void be_init_ssaconstr(void)
430 FIRM_DBG_REGISTER(dbg, "firm.be.ssaconstr");
433 BE_REGISTER_MODULE_CONSTRUCTOR(be_init_ssaconstr);