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.
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 = 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);
123 for (i = 0; i < n_preds; ++i) {
124 ins[i] = new_r_Unknown(irg, env->mode);
126 phi = be_new_Phi(block, n_preds, ins, env->mode, env->phi_cls);
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);
149 static ir_node *get_def_at_idom(be_ssa_construction_env_t *env, ir_node *block)
151 ir_node *dom = get_Block_idom(block);
153 return search_def_end_of_block(env, dom);
156 static ir_node *search_def_end_of_block(be_ssa_construction_env_t *env,
159 if (irn_visited(block)) {
160 assert(get_irn_link(block) != NULL);
161 return get_irn_link(block);
162 } else if (Block_block_visited(block)) {
163 return create_phi(env, block, block);
165 ir_node *def = get_def_at_idom(env, block);
166 mark_irn_visited(block);
167 set_irn_link(block, def);
172 static ir_node *search_def(be_ssa_construction_env_t *env, ir_node *at)
174 ir_node *block = get_nodes_block(at);
178 DBG((dbg, LEVEL_3, "\t...searching def at %+F\n", at));
180 /* no defs in the current block we can do the normal searching */
181 if (!irn_visited(block) && !Block_block_visited(block)) {
182 DBG((dbg, LEVEL_3, "\t...continue at idom\n"));
183 return get_def_at_idom(env, block);
186 /* there are defs in the current block, walk the linked list to find
187 the one immediately dominating us
190 def = get_irn_link(node);
191 while (def != NULL) {
192 if (!value_dominates(at, def)) {
193 DBG((dbg, LEVEL_3, "\t...found dominating def %+F\n", def));
198 def = get_irn_link(node);
201 /* block in dominance frontier? create a phi then */
202 if (Block_block_visited(block)) {
203 DBG((dbg, LEVEL_3, "\t...create phi at block %+F\n", block));
204 assert(!is_Phi(node));
205 return create_phi(env, block, node);
208 DBG((dbg, LEVEL_3, "\t...continue at idom (after checking block)\n"));
209 return get_def_at_idom(env, block);
213 * Adds a definition into the link field of the block. The definitions are
214 * sorted by dominance. A non-visited block means no definition has been
217 static void introduce_def_at_block(ir_node *block, ir_node *def)
219 if (irn_visited_else_mark(block)) {
220 ir_node *node = block;
221 ir_node *current_def;
224 current_def = get_irn_link(node);
225 if (current_def == def) {
226 /* already in block */
229 if (current_def == NULL)
231 if (value_dominates(current_def, def))
236 set_irn_link(node, def);
237 set_irn_link(def, current_def);
239 set_irn_link(block, def);
240 set_irn_link(def, NULL);
244 void be_ssa_construction_init(be_ssa_construction_env_t *env, ir_graph *irg)
246 ir_node *sb = get_irg_start_block(irg);
247 int n_blocks = get_Block_dom_max_subtree_pre_num(sb);
249 stat_ev_ctx_push_fobj("bessaconstr", irg);
253 stat_ev_dbl("bessaconstr_n_blocks", n_blocks);
255 memset(env, 0, sizeof(env[0]));
256 be_assure_dom_front(irg);
259 env->domfronts = be_get_irg_dom_front(irg);
260 env->new_phis = NEW_ARR_F(ir_node*, 0);
261 env->worklist = new_waitq();
263 ir_reserve_resources(irg, IR_RESOURCE_IRN_VISITED
264 | IR_RESOURCE_BLOCK_VISITED | IR_RESOURCE_IRN_LINK);
266 /* we use the visited flag to indicate blocks in the dominance frontier
267 * and blocks that already have the relevant value at the end calculated */
268 inc_irg_visited(irg);
269 /* We use the block visited flag to indicate blocks in the dominance
270 * frontier of some values (and this potentially needing phis) */
271 inc_irg_block_visited(irg);
274 void be_ssa_construction_destroy(be_ssa_construction_env_t *env)
276 stat_ev_int("bessaconstr_phis", ARR_LEN(env->new_phis));
277 del_waitq(env->worklist);
278 DEL_ARR_F(env->new_phis);
280 ir_free_resources(env->irg, IR_RESOURCE_IRN_VISITED
281 | IR_RESOURCE_BLOCK_VISITED | IR_RESOURCE_IRN_LINK);
283 stat_ev_tim_pop("bessaconstr_total_time");
284 stat_ev_ctx_pop("bessaconstr");
287 void be_ssa_construction_add_copy(be_ssa_construction_env_t *env,
292 assert(env->iterated_domfront_calculated == 0);
294 if (env->mode == NULL) {
295 env->mode = get_irn_mode(copy);
296 env->phi_cls = arch_get_irn_reg_class_out(copy);
298 assert(env->mode == get_irn_mode(copy));
301 block = get_nodes_block(copy);
303 if (!irn_visited(block)) {
304 waitq_put(env->worklist, block);
306 introduce_def_at_block(block, copy);
309 void be_ssa_construction_add_copies(be_ssa_construction_env_t *env,
310 ir_node **copies, size_t copies_len)
314 assert(env->iterated_domfront_calculated == 0);
316 if (env->mode == NULL) {
317 env->mode = get_irn_mode(copies[0]);
318 env->phi_cls = arch_get_irn_reg_class_out(copies[0]);
321 for (i = 0; i < copies_len; ++i) {
322 ir_node *copy = copies[i];
323 ir_node *block = get_nodes_block(copy);
325 assert(env->mode == get_irn_mode(copy));
326 if (!irn_visited(block)) {
327 waitq_put(env->worklist, block);
329 introduce_def_at_block(block, copy);
333 void be_ssa_construction_set_ignore_uses(be_ssa_construction_env_t *env,
334 const ir_nodeset_t *ignore_uses)
336 env->ignore_uses = ignore_uses;
339 ir_node **be_ssa_construction_get_new_phis(be_ssa_construction_env_t *env)
341 return env->new_phis;
344 void be_ssa_construction_fix_users_array(be_ssa_construction_env_t *env,
345 ir_node **nodes, size_t nodes_len)
347 const ir_edge_t *edge, *next;
349 stat_ev_cnt_decl(uses);
351 be_timer_push(T_SSA_CONSTR);
353 if (!env->iterated_domfront_calculated) {
354 mark_iterated_dominance_frontiers(env);
355 env->iterated_domfront_calculated = 1;
359 for (i = 0; i < nodes_len; ++i) {
360 ir_node *value = nodes[i];
363 * Search the valid def for each use and set it.
365 foreach_out_edge_safe(value, edge, next) {
366 ir_node *use = get_edge_src_irn(edge);
368 int pos = get_edge_src_pos(edge);
371 if (env->ignore_uses != NULL &&
372 ir_nodeset_contains(env->ignore_uses, use))
374 if (is_Anchor(use) || is_End(use))
378 ir_node *block = get_nodes_block(use);
379 ir_node *predblock = get_Block_cfgpred_block(block, pos);
380 at = sched_last(predblock);
383 def = search_def(env, at);
386 panic("no definition found for %+F at position %d", use, pos);
389 DBG((dbg, LEVEL_2, "\t%+F(%d) -> %+F\n", use, pos, def));
390 set_irn_n(use, pos, def);
391 stat_ev_cnt_inc(uses);
394 be_timer_pop(T_SSA_CONSTR);
396 stat_ev_tim_pop("bessaconstr_fix_time");
397 stat_ev_cnt_done(uses, "bessaconstr_uses");
400 void be_ssa_construction_fix_users(be_ssa_construction_env_t *env, ir_node *value)
402 be_ssa_construction_fix_users_array(env, &value, 1);
406 void be_ssa_construction_update_liveness_phis(be_ssa_construction_env_t *env,
411 be_timer_push(T_SSA_CONSTR);
413 n = ARR_LEN(env->new_phis);
414 for (i = 0; i < n; ++i) {
415 ir_node *phi = env->new_phis[i];
416 be_liveness_introduce(lv, phi);
419 be_timer_pop(T_SSA_CONSTR);
422 BE_REGISTER_MODULE_CONSTRUCTOR(be_init_ssaconstr);
423 void be_init_ssaconstr(void)
425 FIRM_DBG_REGISTER(dbg, "firm.be.ssaconstr");