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"
69 #include "iredges_t.h"
71 DEBUG_ONLY(static firm_dbg_module_t *dbg = NULL;)
74 * Calculates the iterated dominance frontier of a set of blocks. Marks the
75 * blocks as visited. Sets the link fields of the blocks in the dominance
76 * frontier to the block itself.
78 static void mark_iterated_dominance_frontiers(
79 const be_ssa_construction_env_t *env)
81 stat_ev_cnt_decl(blocks);
82 DBG((dbg, LEVEL_3, "Dominance Frontier:"));
84 while (!waitq_empty(env->worklist)) {
86 ir_node *block = (ir_node*)waitq_get(env->worklist);
87 ir_node **domfront = be_get_dominance_frontier(env->domfronts, block);
88 int domfront_len = ARR_LEN(domfront);
90 for (i = 0; i < domfront_len; ++i) {
91 ir_node *y = domfront[i];
92 if (Block_block_visited(y))
95 if (!irn_visited(y)) {
96 set_irn_link(y, NULL);
97 waitq_put(env->worklist, y);
100 DBG((dbg, LEVEL_3, " %+F", y));
101 mark_Block_block_visited(y);
102 stat_ev_cnt_inc(blocks);
105 stat_ev_tim_pop("bessaconstr_idf_time");
106 stat_ev_cnt_done(blocks, "bessaconstr_idf_blocks");
107 DBG((dbg, LEVEL_3, "\n"));
110 static ir_node *search_def_end_of_block(be_ssa_construction_env_t *env,
113 static 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_Block_irg(block);
118 ir_node **ins = ALLOCAN(ir_node*, n_preds);
124 dummy = new_r_Dummy(irg, env->mode);
125 for (i = 0; i < n_preds; ++i) {
128 phi = be_new_Phi(block, n_preds, ins, env->mode, env->phi_cls);
129 sched_add_after(block, phi);
130 if (env->new_phis != NULL) {
131 ARR_APP1(ir_node*, env->new_phis, phi);
134 DBG((dbg, LEVEL_2, "\tcreating phi %+F in %+F\n", phi, block));
135 set_irn_link(link_with, phi);
136 mark_irn_visited(block);
138 for (i = 0; i < n_preds; ++i) {
139 ir_node *pred_block = get_Block_cfgpred_block(block, i);
140 ir_node *pred_def = search_def_end_of_block(env, pred_block);
142 set_irn_n(phi, i, pred_def);
148 static ir_node *get_def_at_idom(be_ssa_construction_env_t *env, ir_node *block)
150 ir_node *dom = get_Block_idom(block);
152 return search_def_end_of_block(env, dom);
155 static ir_node *search_def_end_of_block(be_ssa_construction_env_t *env,
158 if (irn_visited(block)) {
159 assert(get_irn_link(block) != NULL);
160 return (ir_node*)get_irn_link(block);
161 } else if (Block_block_visited(block)) {
162 return create_phi(env, block, block);
164 ir_node *def = get_def_at_idom(env, block);
165 mark_irn_visited(block);
166 set_irn_link(block, def);
171 static ir_node *search_def(be_ssa_construction_env_t *env, ir_node *at)
173 ir_node *block = get_nodes_block(at);
177 DBG((dbg, LEVEL_3, "\t...searching def at %+F\n", at));
179 /* no defs in the current block we can do the normal searching */
180 if (!irn_visited(block) && !Block_block_visited(block)) {
181 DBG((dbg, LEVEL_3, "\t...continue at idom\n"));
182 return get_def_at_idom(env, block);
185 /* there are defs in the current block, walk the linked list to find
186 the one immediately dominating us
189 def = (ir_node*)get_irn_link(node);
190 while (def != NULL) {
191 if (!value_dominates(at, def)) {
192 DBG((dbg, LEVEL_3, "\t...found dominating def %+F\n", def));
197 def = (ir_node*)get_irn_link(node);
200 /* block in dominance frontier? create a phi then */
201 if (Block_block_visited(block)) {
202 DBG((dbg, LEVEL_3, "\t...create phi at block %+F\n", block));
203 assert(!is_Phi(node));
204 return create_phi(env, block, node);
207 DBG((dbg, LEVEL_3, "\t...continue at idom (after checking block)\n"));
208 return get_def_at_idom(env, block);
212 * Adds a definition into the link field of the block. The definitions are
213 * sorted by dominance. A non-visited block means no definition has been
216 static void introduce_def_at_block(ir_node *block, ir_node *def)
218 if (irn_visited_else_mark(block)) {
219 ir_node *node = block;
220 ir_node *current_def;
223 current_def = (ir_node*)get_irn_link(node);
224 if (current_def == def) {
225 /* already in block */
228 if (current_def == NULL)
230 if (value_dominates(current_def, def))
235 set_irn_link(node, def);
236 set_irn_link(def, current_def);
238 set_irn_link(block, def);
239 set_irn_link(def, NULL);
243 void be_ssa_construction_init(be_ssa_construction_env_t *env, ir_graph *irg)
245 ir_node *sb = get_irg_start_block(irg);
246 int n_blocks = get_Block_dom_max_subtree_pre_num(sb);
248 stat_ev_ctx_push_fobj("bessaconstr", irg);
252 stat_ev_dbl("bessaconstr_n_blocks", n_blocks);
254 memset(env, 0, sizeof(env[0]));
255 be_assure_dom_front(irg);
258 env->domfronts = be_get_irg_dom_front(irg);
259 env->new_phis = NEW_ARR_F(ir_node*, 0);
260 env->worklist = new_waitq();
262 ir_reserve_resources(irg, IR_RESOURCE_IRN_VISITED
263 | IR_RESOURCE_BLOCK_VISITED | IR_RESOURCE_IRN_LINK);
265 /* we use the visited flag to indicate blocks in the dominance frontier
266 * and blocks that already have the relevant value at the end calculated */
267 inc_irg_visited(irg);
268 /* We use the block visited flag to indicate blocks in the dominance
269 * frontier of some values (and this potentially needing phis) */
270 inc_irg_block_visited(irg);
273 void be_ssa_construction_destroy(be_ssa_construction_env_t *env)
275 stat_ev_int("bessaconstr_phis", ARR_LEN(env->new_phis));
276 del_waitq(env->worklist);
277 DEL_ARR_F(env->new_phis);
279 ir_free_resources(env->irg, IR_RESOURCE_IRN_VISITED
280 | IR_RESOURCE_BLOCK_VISITED | IR_RESOURCE_IRN_LINK);
282 stat_ev_tim_pop("bessaconstr_total_time");
283 stat_ev_ctx_pop("bessaconstr");
286 void be_ssa_construction_add_copy(be_ssa_construction_env_t *env,
291 assert(env->iterated_domfront_calculated == 0);
293 if (env->mode == NULL) {
294 env->mode = get_irn_mode(copy);
295 env->phi_cls = arch_get_irn_reg_class_out(copy);
297 assert(env->mode == get_irn_mode(copy));
300 block = get_nodes_block(copy);
302 if (!irn_visited(block)) {
303 waitq_put(env->worklist, block);
305 introduce_def_at_block(block, copy);
308 void be_ssa_construction_add_copies(be_ssa_construction_env_t *env,
309 ir_node **copies, size_t copies_len)
313 assert(env->iterated_domfront_calculated == 0);
315 if (env->mode == NULL) {
316 env->mode = get_irn_mode(copies[0]);
317 env->phi_cls = arch_get_irn_reg_class_out(copies[0]);
320 for (i = 0; i < copies_len; ++i) {
321 ir_node *copy = copies[i];
322 ir_node *block = get_nodes_block(copy);
324 assert(env->mode == get_irn_mode(copy));
325 if (!irn_visited(block)) {
326 waitq_put(env->worklist, block);
328 introduce_def_at_block(block, copy);
332 void be_ssa_construction_set_ignore_uses(be_ssa_construction_env_t *env,
333 const ir_nodeset_t *ignore_uses)
335 env->ignore_uses = ignore_uses;
338 ir_node **be_ssa_construction_get_new_phis(be_ssa_construction_env_t *env)
340 return env->new_phis;
343 void be_ssa_construction_fix_users_array(be_ssa_construction_env_t *env,
344 ir_node **nodes, size_t nodes_len)
346 const ir_edge_t *edge, *next;
348 stat_ev_cnt_decl(uses);
350 be_timer_push(T_SSA_CONSTR);
352 if (!env->iterated_domfront_calculated) {
353 mark_iterated_dominance_frontiers(env);
354 env->iterated_domfront_calculated = 1;
358 for (i = 0; i < nodes_len; ++i) {
359 ir_node *value = nodes[i];
362 * Search the valid def for each use and set it.
364 foreach_out_edge_safe(value, edge, next) {
365 ir_node *use = get_edge_src_irn(edge);
367 int pos = get_edge_src_pos(edge);
370 if (env->ignore_uses != NULL &&
371 ir_nodeset_contains(env->ignore_uses, use))
373 if (is_Anchor(use) || is_End(use))
377 ir_node *block = get_nodes_block(use);
378 ir_node *predblock = get_Block_cfgpred_block(block, pos);
379 at = sched_last(predblock);
382 def = search_def(env, at);
385 panic("no definition found for %+F at position %d", use, pos);
388 DBG((dbg, LEVEL_2, "\t%+F(%d) -> %+F\n", use, pos, def));
389 set_irn_n(use, pos, def);
390 stat_ev_cnt_inc(uses);
393 be_timer_pop(T_SSA_CONSTR);
395 stat_ev_tim_pop("bessaconstr_fix_time");
396 stat_ev_cnt_done(uses, "bessaconstr_uses");
399 void be_ssa_construction_fix_users(be_ssa_construction_env_t *env, ir_node *value)
401 be_ssa_construction_fix_users_array(env, &value, 1);
405 void be_ssa_construction_update_liveness_phis(be_ssa_construction_env_t *env,
410 be_timer_push(T_SSA_CONSTR);
412 n = ARR_LEN(env->new_phis);
413 for (i = 0; i < n; ++i) {
414 ir_node *phi = env->new_phis[i];
415 be_liveness_introduce(lv, phi);
418 be_timer_pop(T_SSA_CONSTR);
421 BE_REGISTER_MODULE_CONSTRUCTOR(be_init_ssaconstr);
422 void be_init_ssaconstr(void)
424 FIRM_DBG_REGISTER(dbg, "firm.be.ssaconstr");