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 Partial condition evaluation
24 * @author Christoph Mallon, Matthias Braun
31 #include "iroptimize.h"
43 #include "iredges_t.h"
50 DEBUG_ONLY(static firm_dbg_module_t *dbg);
53 * Add the new predecessor x to node node, which is either a Block or a Phi
55 static void add_pred(ir_node* node, ir_node* x)
61 assert(is_Block(node) || is_Phi(node));
63 n = get_irn_arity(node);
64 NEW_ARR_A(ir_node*, ins, n + 1);
65 for (i = 0; i < n; i++)
66 ins[i] = get_irn_n(node, i);
68 set_irn_in(node, n + 1, ins);
71 static ir_node *search_def_and_create_phis(ir_node *block, ir_mode *mode)
79 // This is needed because we create bads sometimes
83 // already processed this block?
84 if(irn_visited(block)) {
85 ir_node *value = (ir_node*) get_irn_link(block);
89 // blocks with only 1 pred need no phi
90 n_cfgpreds = get_Block_n_cfgpreds(block);
92 ir_node *pred_block = get_Block_cfgpred_block(block, 0);
93 ir_node *value = search_def_and_create_phis(pred_block, mode);
95 set_irn_link(block, value);
96 mark_irn_visited(block);
101 NEW_ARR_A(ir_node*, in, n_cfgpreds);
102 for(i = 0; i < n_cfgpreds; ++i)
103 in[i] = new_Unknown(mode);
105 irg = get_irn_irg(block);
106 phi = new_r_Phi(irg, block, n_cfgpreds, in, mode);
107 set_irn_link(block, phi);
108 mark_irn_visited(block);
111 for(i = 0; i < n_cfgpreds; ++i) {
112 ir_node *pred_block = get_Block_cfgpred_block(block, i);
113 ir_node *pred_val = search_def_and_create_phis(pred_block, mode);
115 set_irn_n(phi, i, pred_val);
122 * Given a set of values this function constructs SSA-form for the users of the
123 * first value (the users are determined through the out-edges of the value).
124 * Uses the irn_visited flags. Works without using the dominance tree.
126 static void construct_ssa(ir_node * const *blocks, ir_node * const *vals, int n_vals)
131 const ir_edge_t *edge;
132 const ir_edge_t *next;
137 irg = get_irn_irg(vals[0]);
138 inc_irg_visited(irg);
140 mode = get_irn_mode(vals[0]);
141 for(i = 0; i < n_vals; ++i) {
142 ir_node *value = vals[i];
143 ir_node *value_block = blocks[i];
145 assert(get_irn_mode(value) == mode);
147 set_irn_link(value_block, value);
148 mark_irn_visited(value_block);
151 // Only fix the users of the first, i.e. the original node
154 // this can happen when fixing phi preds, we mustn't fix the users
155 if(get_nodes_block(value) != blocks[0]) return;
157 foreach_out_edge_safe(value, edge, next) {
158 ir_node *user = get_edge_src_irn(edge);
159 int j = get_edge_src_pos(edge);
160 ir_node *user_block = get_nodes_block(user);
164 if(get_irn_op(user) == op_End)
167 DB((dbg, LEVEL_3, ">>> Fixing user %+F (pred %d == %+F)\n", user, j, get_irn_n(user, j)));
170 ir_node *pred_block = get_Block_cfgpred_block(user_block, j);
171 newval = search_def_and_create_phis(pred_block, mode);
173 newval = search_def_and_create_phis(user_block, mode);
176 // don't fix newly created phis from the SSA construction
177 if (newval != user) {
178 DB((dbg, LEVEL_4, ">>>> Setting input %d of %+F to %+F\n", j, user, newval));
179 set_irn_n(user, j, newval);
184 static void split_critical_edge(ir_node *block, int pos) {
185 ir_graph *irg = get_irn_irg(block);
190 in[0] = get_Block_cfgpred(block, pos);
191 new_block = new_r_Block(irg, 1, in);
192 new_jmp = new_r_Jmp(irg, new_block);
193 set_Block_cfgpred(block, pos, new_jmp);
196 typedef struct condeval_env_t {
201 unsigned long visited_nr;
203 ir_node *cnst_pred; /**< the block before the constant */
204 int cnst_pos; /**< the pos to the constant block (needed to
205 kill that edge later) */
208 static void copy_and_fix(const condeval_env_t *env, ir_node *block,
209 ir_node *copy_block, int j) {
210 const ir_edge_t *edge;
212 /* Look at all nodes in the cond_block and copy them into pred */
213 foreach_out_edge(block, edge) {
214 ir_node *node = get_edge_src_irn(edge);
216 ir_mode *mode = get_irn_mode(node);
218 /* ignore control flow */
219 if (mode == mode_X || is_Cond(node))
222 /* we may not copy mode_b nodes, because this could produce phi with
223 * mode_bs which can't be handled in all backends. Instead we duplicate
224 * the node and move it to it's users */
225 if (mode == mode_b) {
226 const ir_edge_t *edge, *next;
230 assert(is_Proj(node));
232 pred = get_Proj_pred(node);
233 pn = get_Proj_proj(node);
235 foreach_out_edge_safe(node, edge, next) {
237 ir_node *user = get_edge_src_irn(edge);
238 int pos = get_edge_src_pos(edge);
239 ir_node *user_block = get_nodes_block(user);
241 if(user_block == block)
244 cmp_copy = exact_copy(pred);
245 set_nodes_block(cmp_copy, user_block);
246 copy = new_r_Proj(current_ir_graph, user_block, cmp_copy, mode_b, pn);
247 set_irn_n(user, pos, copy);
253 /* we can evaluate Phis right now, all other nodes get copied */
255 copy = get_Phi_pred(node, j);
257 copy = exact_copy(node);
258 set_nodes_block(copy, copy_block);
261 set_irn_link(node, copy);
262 set_irn_visited(node, env->visited_nr);
264 /* we might hit values in blocks that have already been processed by a
265 * recursive find_phi_with_const call */
266 assert(get_irn_visited(copy) <= env->visited_nr);
267 if(get_irn_visited(copy) >= env->visited_nr) {
268 ir_node *prev_copy = get_irn_link(copy);
269 if(prev_copy != NULL)
270 set_irn_link(node, prev_copy);
274 /* fix data-flow (and reconstruct SSA if needed) */
275 foreach_out_edge(block, edge) {
278 ir_node *node = get_edge_src_irn(edge);
279 ir_mode *mode = get_irn_mode(node);
281 if (mode == mode_X || is_Cond(node))
288 DB((dbg, LEVEL_2, ">> Fixing users of %+F\n", node));
292 blocks[1] = copy_block;
293 vals[1] = get_irn_link(node);
294 construct_ssa(blocks, vals, 2);
298 static int eval_cmp(pn_Cmp pnc, tarval *tv1, tarval *tv2) {
299 pn_Cmp cmp_result = tarval_cmp(tv1, tv2);
301 // does the compare evaluate to true?
302 if(cmp_result == pn_Cmp_False)
304 if((cmp_result & pnc) != cmp_result)
310 static ir_node *find_const(condeval_env_t *env, ir_node *jump, ir_node *value)
312 ir_node *block = get_nodes_block(jump);
314 if(irn_visited(value))
316 mark_irn_visited(value);
318 if(is_Const(value)) {
319 tarval *tv_const = get_Const_tarval(env->cnst);
320 tarval *tv = get_Const_tarval(value);
322 if(!eval_cmp(env->pnc, tv, tv_const)) {
328 "> Found condition evaluation candidate %+F->%+F\n",
329 env->true_block, block
332 // adjust true_block to point directly towards our jump
333 add_pred(env->true_block, jump);
335 split_critical_edge(env->true_block, 0);
337 // we need a bigger visited nr when going back
346 // the phi has to be in the same block as the jump
347 if(get_nodes_block(value) != block) {
351 arity = get_irn_arity(value);
352 for(i = 0; i < arity; ++i) {
354 ir_node *phi_pred = get_Phi_pred(value, i);
355 ir_node *cfgpred = get_Block_cfgpred(block, i);
357 copy_block = find_const(env, cfgpred, phi_pred);
358 if(copy_block == NULL)
361 /* copy duplicated nodes in copy_block and fix SSA */
362 copy_and_fix(env, block, copy_block, i);
364 if(copy_block == get_nodes_block(cfgpred)) {
365 env->cnst_pred = block;
369 // return now as we can't process more possibilities in 1 run
377 static ir_node *find_candidate(condeval_env_t *env, ir_node *jump,
380 ir_node *block = get_nodes_block(jump);
382 if(irn_visited(value)) {
385 mark_irn_visited(value);
387 if(is_Const(value)) {
388 tarval *tv = get_Const_tarval(value);
395 "> Found condition evaluation candidate %+F->%+F\n",
396 env->true_block, block
399 // adjust true_block to point directly towards our jump
400 add_pred(env->true_block, jump);
402 split_critical_edge(env->true_block, 0);
404 // we need a bigger visited nr when going back
412 // the phi has to be in the same block as the jump
413 if(get_nodes_block(value) != block)
416 arity = get_irn_arity(value);
417 for(i = 0; i < arity; ++i) {
419 ir_node *phi_pred = get_Phi_pred(value, i);
420 ir_node *cfgpred = get_Block_cfgpred(block, i);
422 copy_block = find_candidate(env, cfgpred, phi_pred);
423 if(copy_block == NULL)
426 /* copy duplicated nodes in copy_block and fix SSA */
427 copy_and_fix(env, block, copy_block, i);
429 if(copy_block == get_nodes_block(cfgpred)) {
430 env->cnst_pred = block;
434 // return now as we can't process more possibilities in 1 run
442 ir_node *cmp = get_Proj_pred(value);
446 left = get_Cmp_left(cmp);
447 right = get_Cmp_right(cmp);
448 pnc = get_Proj_proj(value);
450 /* we assume that the constant is on the right side, swap left/right
457 pnc = get_inversed_pnc(pnc);
463 if(get_nodes_block(left) != block) {
467 /* negate condition when we're looking for the false block */
468 if(env->tv == get_tarval_b_false()) {
469 pnc = get_negated_pnc(pnc, get_irn_mode(right));
472 // (recursively) look if a pred of a phi is a constant
476 return find_const(env, jump, left);
483 * Block-walker: searches for the following construct
485 * Const or Phi with constants
495 static void cond_eval(ir_node* block, void* data)
503 const ir_edge_t *edge, *next;
507 if(get_Block_n_cfgpreds(block) != 1)
510 projx = get_Block_cfgpred(block, 0);
513 assert(get_irn_mode(projx) == mode_X);
515 cond = get_Proj_pred(projx);
519 selector = get_Cond_selector(cond);
520 // TODO handle switch Conds
521 if (get_irn_mode(selector) != mode_b)
524 if (get_Proj_proj(projx) == pn_Cond_false) {
525 env.tv = get_tarval_b_false();
527 env.tv = get_tarval_b_true();
530 // (recursively) look if a pred of a phi is a constant
531 env.true_block = block;
532 inc_irg_visited(current_ir_graph);
533 env.visited_nr = get_irg_visited(current_ir_graph);
535 copy_block = find_candidate(&env, projx, selector);
536 if (copy_block == NULL)
539 /* we have to remove the edge towards the pred as the pred now
540 * jumps into the true_block. We also have to shorten phis
541 * in our block because of this */
543 cnst_pos = env.cnst_pos;
546 foreach_out_edge_safe(env.cnst_pred, edge, next) {
547 ir_node *node = get_edge_src_irn(edge);
550 set_Phi_pred(node, cnst_pos, bad);
553 set_Block_cfgpred(env.cnst_pred, cnst_pos, bad);
555 /* the graph is changed now */
559 void opt_cond_eval(ir_graph* irg)
563 FIRM_DBG_REGISTER(dbg, "firm.opt.condeval");
565 DB((dbg, LEVEL_1, "===> Performing condition evaluation on %+F\n", irg));
567 remove_critical_cf_edges(irg);
568 normalize_proj_nodes(irg);
571 set_using_irn_link(irg);
572 set_using_visited(irg);
577 irg_block_walk_graph(irg, cond_eval, NULL, &rerun);
582 /* control flow changed, some blocks may become dead */
583 set_irg_outs_inconsistent(irg);
584 set_irg_doms_inconsistent(irg);
585 set_irg_extblk_inconsistent(irg);
586 set_irg_loopinfo_inconsistent(irg);
589 clear_using_visited(irg);
590 clear_using_irn_link(irg);