2 * Copyright (C) 1995-2007 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. The
33 * we search for each use all 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 search do the same search for
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"
66 #include "iredges_t.h"
68 DEBUG_ONLY(static firm_dbg_module_t *dbg = NULL;)
71 * Calculates the iterated dominance frontier of a set of blocks. Marks the
72 * blocks as visited. Sets the link fields of the blocks in the dominance
73 * frontier to the block itself.
76 void mark_iterated_dominance_frontiers(const be_dom_front_info_t *domfronts,
79 DBG((dbg, LEVEL_3, "Dominance Frontier:"));
80 while(!pdeq_empty(worklist)) {
82 ir_node *block = waitq_get(worklist);
83 ir_node **domfront = be_get_dominance_frontier(domfronts, block);
84 int domfront_len = ARR_LEN(domfront);
86 for (i = 0; i < domfront_len; ++i) {
87 ir_node *y = domfront[i];
88 if(Block_block_visited(y))
92 set_irn_link(y, NULL);
93 waitq_put(worklist, y);
95 DBG((dbg, LEVEL_3, " %+F", y));
96 mark_Block_block_visited(y);
99 DBG((dbg, LEVEL_3, "\n"));
103 ir_node *search_def_end_of_block(be_ssa_construction_env_t *env,
107 ir_node *create_phi(be_ssa_construction_env_t *env, ir_node *block,
110 int i, n_preds = get_Block_n_cfgpreds(block);
111 ir_graph *irg = get_irn_irg(block);
113 ir_node **ins = alloca(n_preds * sizeof(ins[0]));
117 for(i = 0; i < n_preds; ++i) {
118 ins[i] = new_r_Unknown(irg, env->mode);
120 phi = new_r_Phi(irg, block, n_preds, ins, env->mode);
121 if(env->new_phis != NULL) {
122 ARR_APP1(ir_node*, env->new_phis, phi);
125 if(env->mode != mode_M) {
126 sched_add_after(block, phi);
129 DBG((dbg, LEVEL_2, "\tcreating phi %+F in %+F\n", phi, block));
130 set_irn_link(link_with, phi);
131 mark_irn_visited(block);
133 for(i = 0; i < n_preds; ++i) {
134 ir_node *pred_block = get_Block_cfgpred_block(block, i);
135 ir_node *pred_def = search_def_end_of_block(env, pred_block);
137 set_irn_n(phi, i, pred_def);
144 ir_node *get_def_at_idom(be_ssa_construction_env_t *env, ir_node *block)
146 ir_node *dom = get_Block_idom(block);
148 return search_def_end_of_block(env, dom);
152 ir_node *search_def_end_of_block(be_ssa_construction_env_t *env, ir_node *block)
154 if(irn_visited(block)) {
155 assert(get_irn_link(block) != NULL);
156 return get_irn_link(block);
157 } else if(Block_block_visited(block)) {
158 return create_phi(env, block, block);
160 ir_node *def = get_def_at_idom(env, block);
161 mark_irn_visited(block);
162 set_irn_link(block, def);
169 ir_node *search_def(be_ssa_construction_env_t *env, ir_node *at)
171 ir_node *block = get_nodes_block(at);
175 DBG((dbg, LEVEL_3, "\t...searching def at %+F\n", at));
177 /* no defs in the current block we can do the normal searching */
178 if(!irn_visited(block) && !Block_block_visited(block)) {
179 DBG((dbg, LEVEL_3, "\t...continue at idom\n"));
180 return get_def_at_idom(env, block);
183 /* there are defs in the current block, walk the linked list to find
184 the one immediately dominating us
187 def = get_irn_link(node);
189 if(!value_dominates(at, def)) {
190 DBG((dbg, LEVEL_3, "\t...found dominating def %+F\n", def));
195 def = get_irn_link(node);
198 /* block in dominance frontier? create a phi then */
199 if(Block_block_visited(block)) {
200 DBG((dbg, LEVEL_3, "\t...create phi at block %+F\n", block));
201 assert(!is_Phi(node));
202 return create_phi(env, block, node);
205 DBG((dbg, LEVEL_3, "\t...continue at idom (after checking block)\n"));
206 return get_def_at_idom(env, block);
210 * Adds a definition into the link field of the block. The definitions are
211 * sorted by dominance. A non-visited block means no definition has been
215 void introduce_def_at_block(ir_node *block, ir_node *def)
217 if(irn_visited(block)) {
218 ir_node *node = block;
219 ir_node *current_def;
222 current_def = get_irn_link(node);
223 if(current_def == def) {
224 /* already in block */
227 if(current_def == NULL)
229 if(value_dominates(current_def, def))
234 set_irn_link(node, def);
235 set_irn_link(def, current_def);
237 set_irn_link(block, def);
238 set_irn_link(def, NULL);
239 mark_irn_visited(block);
243 void be_ssa_construction_init(be_ssa_construction_env_t *env, be_irg_t *birg)
245 ir_graph *irg = be_get_birg_irg(birg);
246 memset(env, 0, sizeof(env[0]));
248 be_assure_dom_front(birg);
251 env->domfronts = be_get_birg_dom_front(birg);
252 env->new_phis = NEW_ARR_F(ir_node*, 0);
253 env->worklist = new_waitq();
255 set_using_visited(irg);
256 set_using_block_visited(irg);
257 set_using_irn_link(irg);
259 /* we use the visited flag to indicate blocks in the dominance frontier
260 * and blocks that already have the relevant value at the end calculated */
261 inc_irg_visited(irg);
262 /* We use the block visited flag to indicate blocks in the dominance
263 * froniter of some values (and this potentially needing phis) */
264 inc_irg_block_visited(irg);
267 void be_ssa_construction_destroy(be_ssa_construction_env_t *env)
269 del_waitq(env->worklist);
270 DEL_ARR_F(env->new_phis);
272 clear_using_visited(env->irg);
273 clear_using_block_visited(env->irg);
274 clear_using_irn_link(env->irg);
277 void be_ssa_construction_add_copy(be_ssa_construction_env_t *env,
282 assert(env->iterated_domfront_calculated == 0);
284 if(env->mode == NULL) {
285 env->mode = get_irn_mode(copy);
287 assert(env->mode == get_irn_mode(copy));
290 block = get_nodes_block(copy);
292 if(!irn_visited(block)) {
293 waitq_put(env->worklist, block);
295 introduce_def_at_block(block, copy);
298 void be_ssa_construction_add_copies(be_ssa_construction_env_t *env,
299 ir_node **copies, size_t copies_len)
303 assert(env->iterated_domfront_calculated == 0);
305 if(env->mode == NULL) {
306 env->mode = get_irn_mode(copies[0]);
309 for(i = 0; i < copies_len; ++i) {
310 ir_node *copy = copies[i];
311 ir_node *block = get_nodes_block(copy);
313 assert(env->mode == get_irn_mode(copy));
314 if(!irn_visited(block)) {
315 waitq_put(env->worklist, block);
317 introduce_def_at_block(block, copy);
321 void be_ssa_construction_set_ignore_uses(be_ssa_construction_env_t *env,
322 const ir_nodeset_t *ignore_uses)
324 env->ignore_uses = ignore_uses;
327 ir_node **be_ssa_construction_get_new_phis(be_ssa_construction_env_t *env)
329 return env->new_phis;
332 void be_ssa_construction_fix_users(be_ssa_construction_env_t *env,
335 const ir_edge_t *edge, *next;
337 if(!env->iterated_domfront_calculated) {
338 mark_iterated_dominance_frontiers(env->domfronts, env->worklist);
339 env->iterated_domfront_calculated = 1;
343 * Search the valid def for each use and set it.
345 foreach_out_edge_safe(value, edge, next) {
346 ir_node *use = get_edge_src_irn(edge);
348 int pos = get_edge_src_pos(edge);
351 if(env->ignore_uses != NULL &&
352 ir_nodeset_contains(env->ignore_uses, use))
358 ir_node *block = get_nodes_block(use);
359 ir_node *predblock = get_Block_cfgpred_block(block, pos);
360 at = sched_last(predblock);
363 def = search_def(env, at);
366 panic("no definition found for %+F at position %d\n", use, pos);
369 DBG((dbg, LEVEL_2, "\t%+F(%d) -> %+F\n", use, pos, def));
370 set_irn_n(use, pos, def);
374 void be_ssa_construction_fix_users_array(be_ssa_construction_env_t *env,
375 ir_node **nodes, size_t nodes_len)
379 for(i = 0; i < nodes_len; ++i) {
380 ir_node *node = nodes[i];
381 be_ssa_construction_fix_users(env, node);
385 void be_ssa_construction_update_liveness_phis(be_ssa_construction_env_t *env,
390 n = ARR_LEN(env->new_phis);
391 for(i = 0; i < n; ++i) {
392 ir_node *phi = env->new_phis[i];
393 be_liveness_introduce(lv, phi);
397 void be_init_ssaconstr(void)
399 FIRM_DBG_REGISTER(dbg, "firm.be.ssaconstr");
402 BE_REGISTER_MODULE_CONSTRUCTOR(be_init_ssaconstr);