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 #include "bessaconstr.h"
55 #include "besched_t.h"
56 #include "beintlive_t.h"
67 #include "iredges_t.h"
69 DEBUG_ONLY(static firm_dbg_module_t *dbg = NULL;)
72 * Calculates the iterated dominance frontier of a set of blocks. Marks the
73 * blocks as visited. Sets the link fields of the blocks in the dominance
74 * frontier to the block itself.
77 void mark_iterated_dominance_frontiers(const be_ssa_construction_env_t *env)
79 stat_ev_cnt_decl(blocks);
80 DBG((dbg, LEVEL_3, "Dominance Frontier:"));
82 while (!waitq_empty(env->worklist)) {
84 ir_node *block = waitq_get(env->worklist);
85 ir_node **domfront = be_get_dominance_frontier(env->domfronts, block);
86 int domfront_len = ARR_LEN(domfront);
88 for (i = 0; i < domfront_len; ++i) {
89 ir_node *y = domfront[i];
90 if (Block_block_visited(y))
93 if (!irn_visited(y)) {
94 set_irn_link(y, NULL);
95 waitq_put(env->worklist, y);
98 DBG((dbg, LEVEL_3, " %+F", y));
99 mark_Block_block_visited(y);
100 stat_ev_cnt_inc(blocks);
103 stat_ev_tim_pop("bessaconstr_idf_time");
104 stat_ev_cnt_done(blocks, "bessaconstr_idf_blocks");
105 DBG((dbg, LEVEL_3, "\n"));
109 ir_node *search_def_end_of_block(be_ssa_construction_env_t *env,
113 ir_node *create_phi(be_ssa_construction_env_t *env, ir_node *block,
116 int i, n_preds = get_Block_n_cfgpreds(block);
117 ir_graph *irg = get_irn_irg(block);
119 ir_node **ins = alloca(n_preds * sizeof(ins[0]));
123 for(i = 0; i < n_preds; ++i) {
124 ins[i] = new_r_Unknown(irg, env->mode);
126 phi = new_r_Phi(irg, block, n_preds, ins, env->mode);
127 if(env->new_phis != NULL) {
128 ARR_APP1(ir_node*, env->new_phis, phi);
131 if(env->mode != mode_M) {
132 sched_add_after(block, phi);
135 DBG((dbg, LEVEL_2, "\tcreating phi %+F in %+F\n", phi, block));
136 set_irn_link(link_with, phi);
137 mark_irn_visited(block);
139 for(i = 0; i < n_preds; ++i) {
140 ir_node *pred_block = get_Block_cfgpred_block(block, i);
141 ir_node *pred_def = search_def_end_of_block(env, pred_block);
143 set_irn_n(phi, i, pred_def);
150 ir_node *get_def_at_idom(be_ssa_construction_env_t *env, ir_node *block)
152 ir_node *dom = get_Block_idom(block);
154 return search_def_end_of_block(env, dom);
158 ir_node *search_def_end_of_block(be_ssa_construction_env_t *env, ir_node *block)
160 if(irn_visited(block)) {
161 assert(get_irn_link(block) != NULL);
162 return get_irn_link(block);
163 } else if(Block_block_visited(block)) {
164 return create_phi(env, block, block);
166 ir_node *def = get_def_at_idom(env, block);
167 mark_irn_visited(block);
168 set_irn_link(block, def);
174 ir_node *search_def(be_ssa_construction_env_t *env, ir_node *at)
176 ir_node *block = get_nodes_block(at);
180 DBG((dbg, LEVEL_3, "\t...searching def at %+F\n", at));
182 /* no defs in the current block we can do the normal searching */
183 if(!irn_visited(block) && !Block_block_visited(block)) {
184 DBG((dbg, LEVEL_3, "\t...continue at idom\n"));
185 return get_def_at_idom(env, block);
188 /* there are defs in the current block, walk the linked list to find
189 the one immediately dominating us
192 def = get_irn_link(node);
194 if(!value_dominates(at, def)) {
195 DBG((dbg, LEVEL_3, "\t...found dominating def %+F\n", def));
200 def = get_irn_link(node);
203 /* block in dominance frontier? create a phi then */
204 if(Block_block_visited(block)) {
205 DBG((dbg, LEVEL_3, "\t...create phi at block %+F\n", block));
206 assert(!is_Phi(node));
207 return create_phi(env, block, node);
210 DBG((dbg, LEVEL_3, "\t...continue at idom (after checking block)\n"));
211 return get_def_at_idom(env, block);
215 * Adds a definition into the link field of the block. The definitions are
216 * sorted by dominance. A non-visited block means no definition has been
220 void introduce_def_at_block(ir_node *block, ir_node *def)
222 if(irn_visited(block)) {
223 ir_node *node = block;
224 ir_node *current_def;
227 current_def = get_irn_link(node);
228 if(current_def == def) {
229 /* already in block */
232 if(current_def == NULL)
234 if(value_dominates(current_def, def))
239 set_irn_link(node, def);
240 set_irn_link(def, current_def);
242 set_irn_link(block, def);
243 set_irn_link(def, NULL);
244 mark_irn_visited(block);
248 void be_ssa_construction_init(be_ssa_construction_env_t *env, be_irg_t *birg)
250 ir_graph *irg = be_get_birg_irg(birg);
251 ir_node *sb = get_irg_start_block(irg);
252 int n_blocks = get_Block_dom_max_subtree_pre_num(sb);
254 stat_ev_ctx_push_fobj("bessaconstr", irg);
258 stat_ev_dbl("bessaconstr_n_blocks", n_blocks);
260 memset(env, 0, sizeof(env[0]));
261 be_assure_dom_front(birg);
264 env->domfronts = be_get_birg_dom_front(birg);
265 env->new_phis = NEW_ARR_F(ir_node*, 0);
266 env->worklist = new_waitq();
268 ir_reserve_resources(irg, IR_RESOURCE_IRN_VISITED
269 | IR_RESOURCE_BLOCK_VISITED | IR_RESOURCE_IRN_LINK);
271 /* we use the visited flag to indicate blocks in the dominance frontier
272 * and blocks that already have the relevant value at the end calculated */
273 inc_irg_visited(irg);
274 /* We use the block visited flag to indicate blocks in the dominance
275 * frontier of some values (and this potentially needing phis) */
276 inc_irg_block_visited(irg);
279 void be_ssa_construction_destroy(be_ssa_construction_env_t *env)
281 stat_ev_int("bessaconstr_phis", ARR_LEN(env->new_phis));
282 del_waitq(env->worklist);
283 DEL_ARR_F(env->new_phis);
285 ir_free_resources(env->irg, IR_RESOURCE_IRN_VISITED
286 | IR_RESOURCE_BLOCK_VISITED | IR_RESOURCE_IRN_LINK);
288 stat_ev_tim_pop("bessaconstr_total_time");
289 stat_ev_ctx_pop("bessaconstr");
292 void be_ssa_construction_add_copy(be_ssa_construction_env_t *env,
297 assert(env->iterated_domfront_calculated == 0);
299 if(env->mode == NULL) {
300 env->mode = get_irn_mode(copy);
302 assert(env->mode == get_irn_mode(copy));
305 block = get_nodes_block(copy);
307 if(!irn_visited(block)) {
308 waitq_put(env->worklist, block);
310 introduce_def_at_block(block, copy);
313 void be_ssa_construction_add_copies(be_ssa_construction_env_t *env,
314 ir_node **copies, size_t copies_len)
318 assert(env->iterated_domfront_calculated == 0);
320 if(env->mode == NULL) {
321 env->mode = get_irn_mode(copies[0]);
324 for(i = 0; i < copies_len; ++i) {
325 ir_node *copy = copies[i];
326 ir_node *block = get_nodes_block(copy);
328 assert(env->mode == get_irn_mode(copy));
329 if(!irn_visited(block)) {
330 waitq_put(env->worklist, block);
332 introduce_def_at_block(block, copy);
336 void be_ssa_construction_set_ignore_uses(be_ssa_construction_env_t *env,
337 const ir_nodeset_t *ignore_uses)
339 env->ignore_uses = ignore_uses;
342 ir_node **be_ssa_construction_get_new_phis(be_ssa_construction_env_t *env)
344 return env->new_phis;
347 void be_ssa_construction_fix_users_array(be_ssa_construction_env_t *env,
348 ir_node **nodes, size_t nodes_len)
350 stat_ev_cnt_decl(uses);
351 const ir_edge_t *edge, *next;
354 BE_TIMER_PUSH(t_ssa_constr);
356 if(!env->iterated_domfront_calculated) {
357 mark_iterated_dominance_frontiers(env);
358 env->iterated_domfront_calculated = 1;
362 for(i = 0; i < nodes_len; ++i) {
363 ir_node *value = nodes[i];
366 * Search the valid def for each use and set it.
368 foreach_out_edge_safe(value, edge, next) {
369 ir_node *use = get_edge_src_irn(edge);
371 int pos = get_edge_src_pos(edge);
374 if(env->ignore_uses != NULL &&
375 ir_nodeset_contains(env->ignore_uses, use))
381 ir_node *block = get_nodes_block(use);
382 ir_node *predblock = get_Block_cfgpred_block(block, pos);
383 at = sched_last(predblock);
386 def = search_def(env, at);
389 panic("no definition found for %+F at position %d\n", use, pos);
392 DBG((dbg, LEVEL_2, "\t%+F(%d) -> %+F\n", use, pos, def));
393 set_irn_n(use, pos, def);
394 stat_ev_cnt_inc(uses);
397 BE_TIMER_POP(t_ssa_constr);
399 stat_ev_tim_pop("bessaconstr_fix_time");
400 stat_ev_cnt_done(uses, "bessaconstr_uses");
403 void be_ssa_construction_fix_users(be_ssa_construction_env_t *env, ir_node *value)
405 be_ssa_construction_fix_users_array(env, &value, 1);
409 void be_ssa_construction_update_liveness_phis(be_ssa_construction_env_t *env,
414 BE_TIMER_PUSH(t_ssa_constr);
416 n = ARR_LEN(env->new_phis);
417 for(i = 0; i < n; ++i) {
418 ir_node *phi = env->new_phis[i];
419 be_liveness_introduce(lv, phi);
422 BE_TIMER_POP(t_ssa_constr);
425 void be_init_ssaconstr(void)
427 FIRM_DBG_REGISTER(dbg, "firm.be.ssaconstr");
430 BE_REGISTER_MODULE_CONSTRUCTOR(be_init_ssaconstr);