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"
48 DEBUG_ONLY(static firm_dbg_module_t *dbg);
51 * Add the new predecessor x to node node, which is either a Block or a Phi
53 static void add_pred(ir_node* node, ir_node* x)
59 assert(is_Block(node) || is_Phi(node));
61 n = get_irn_arity(node);
62 NEW_ARR_A(ir_node*, ins, n + 1);
63 for (i = 0; i < n; i++)
64 ins[i] = get_irn_n(node, i);
66 set_irn_in(node, n + 1, ins);
69 static ir_node *search_def_and_create_phis(ir_node *block, ir_mode *mode)
77 // This is needed because we create bads sometimes
81 // already processed this block?
82 if(irn_visited(block)) {
83 ir_node *value = (ir_node*) get_irn_link(block);
87 // blocks with only 1 pred need no phi
88 n_cfgpreds = get_Block_n_cfgpreds(block);
90 ir_node *pred_block = get_Block_cfgpred_block(block, 0);
91 ir_node *value = search_def_and_create_phis(pred_block, mode);
93 set_irn_link(block, value);
94 mark_irn_visited(block);
99 NEW_ARR_A(ir_node*, in, n_cfgpreds);
100 for(i = 0; i < n_cfgpreds; ++i)
101 in[i] = new_Unknown(mode);
103 irg = get_irn_irg(block);
104 phi = new_r_Phi(irg, block, n_cfgpreds, in, mode);
105 set_irn_link(block, phi);
106 mark_irn_visited(block);
109 for(i = 0; i < n_cfgpreds; ++i) {
110 ir_node *pred_block = get_Block_cfgpred_block(block, i);
111 ir_node *pred_val = search_def_and_create_phis(pred_block, mode);
113 set_irn_n(phi, i, pred_val);
120 * Given a set of values this function constructs SSA-form for the users of the
121 * first value (the users are determined through the out-edges of the value).
122 * Uses the irn_visited flags. Works without using the dominance tree.
124 static void construct_ssa(ir_node * const *blocks, ir_node * const *vals, int n_vals)
129 const ir_edge_t *edge;
130 const ir_edge_t *next;
135 irg = get_irn_irg(vals[0]);
136 inc_irg_visited(irg);
138 mode = get_irn_mode(vals[0]);
139 for(i = 0; i < n_vals; ++i) {
140 ir_node *value = vals[i];
141 ir_node *value_block = blocks[i];
143 assert(get_irn_mode(value) == mode);
145 set_irn_link(value_block, value);
146 mark_irn_visited(value_block);
149 // Only fix the users of the first, i.e. the original node
152 // this can happen when fixing phi preds, we mustn't fix the users
153 if(get_nodes_block(value) != blocks[0]) return;
155 foreach_out_edge_safe(value, edge, next) {
156 ir_node *user = get_edge_src_irn(edge);
157 int j = get_edge_src_pos(edge);
158 ir_node *user_block = get_nodes_block(user);
162 if(get_irn_op(user) == op_End)
165 DB((dbg, LEVEL_3, ">>> Fixing user %+F (pred %d == %+F)\n", user, j, get_irn_n(user, j)));
168 ir_node *pred_block = get_Block_cfgpred_block(user_block, j);
169 newval = search_def_and_create_phis(pred_block, mode);
171 newval = search_def_and_create_phis(user_block, mode);
174 // don't fix newly created phis from the SSA construction
175 if (newval != user) {
176 DB((dbg, LEVEL_4, ">>>> Setting input %d of %+F to %+F\n", j, user, newval));
177 set_irn_n(user, j, newval);
182 static void split_critical_edge(ir_node *block, int pos) {
183 ir_graph *irg = get_irn_irg(block);
188 in[0] = get_Block_cfgpred(block, pos);
189 new_block = new_r_Block(irg, 1, in);
190 new_jmp = new_r_Jmp(irg, new_block);
191 set_Block_cfgpred(block, pos, new_jmp);
194 typedef struct condeval_env_t {
199 unsigned long visited_nr;
201 ir_node *cnst_pred; /**< the block before the constant */
202 int cnst_pos; /**< the pos to the constant block (needed to
203 kill that edge later) */
206 static void copy_and_fix(const condeval_env_t *env, ir_node *block,
207 ir_node *copy_block, int j) {
208 const ir_edge_t *edge;
210 /* Look at all nodes in the cond_block and copy them into pred */
211 foreach_out_edge(block, edge) {
212 ir_node *node = get_edge_src_irn(edge);
214 ir_mode *mode = get_irn_mode(node);
216 /* ignore control flow */
217 if (mode == mode_X || is_Cond(node))
220 /* we may not copy mode_b nodes, because this could produce phi with
221 * mode_bs which can't be handled in all backends. Instead we duplicate
222 * the node and move it to it's users */
223 if (mode == mode_b) {
224 const ir_edge_t *edge, *next;
228 assert(is_Proj(node));
230 pred = get_Proj_pred(node);
231 pn = get_Proj_proj(node);
233 foreach_out_edge_safe(node, edge, next) {
235 ir_node *user = get_edge_src_irn(edge);
236 int pos = get_edge_src_pos(edge);
237 ir_node *user_block = get_nodes_block(user);
239 if(user_block == block)
242 cmp_copy = exact_copy(pred);
243 set_nodes_block(cmp_copy, user_block);
244 copy = new_r_Proj(current_ir_graph, user_block, cmp_copy, mode_b, pn);
245 set_irn_n(user, pos, copy);
251 /* we can evaluate Phis right now, all other nodes get copied */
253 copy = get_Phi_pred(node, j);
255 copy = exact_copy(node);
256 set_nodes_block(copy, copy_block);
259 set_irn_link(node, copy);
260 set_irn_visited(node, env->visited_nr);
262 /* we might hit values in blocks that have already been processed by a
263 * recursive find_phi_with_const call */
264 assert(get_irn_visited(copy) <= env->visited_nr);
265 if(get_irn_visited(copy) >= env->visited_nr) {
266 ir_node *prev_copy = get_irn_link(copy);
267 if(prev_copy != NULL)
268 set_irn_link(node, prev_copy);
272 /* fix data-flow (and reconstruct SSA if needed) */
273 foreach_out_edge(block, edge) {
276 ir_node *node = get_edge_src_irn(edge);
277 ir_mode *mode = get_irn_mode(node);
279 if (mode == mode_X || is_Cond(node))
284 DB((dbg, LEVEL_2, ">> Fixing users of %+F\n", node));
288 blocks[1] = copy_block;
289 vals[1] = get_irn_link(node);
290 construct_ssa(blocks, vals, 2);
294 static int eval_cmp(pn_Cmp pnc, tarval *tv1, tarval *tv2) {
295 pn_Cmp cmp_result = tarval_cmp(tv1, tv2);
297 // does the compare evaluate to true?
298 if(cmp_result == pn_Cmp_False)
300 if((cmp_result & pnc) != cmp_result)
306 static ir_node *find_const(condeval_env_t *env, ir_node *jump, ir_node *value)
308 ir_node *block = get_nodes_block(jump);
310 if(irn_visited(value))
312 mark_irn_visited(value);
314 if(is_Const(value)) {
315 tarval *tv_const = get_Const_tarval(env->cnst);
316 tarval *tv = get_Const_tarval(value);
318 if(!eval_cmp(env->pnc, tv, tv_const)) {
324 "> Found condition evaluation candidate %+F->%+F\n",
325 env->true_block, block
328 // adjust true_block to point directly towards our jump
329 add_pred(env->true_block, jump);
331 split_critical_edge(env->true_block, 0);
333 // we need a bigger visited nr when going back
342 // the phi has to be in the same block as the jump
343 if(get_nodes_block(value) != block) {
347 arity = get_irn_arity(value);
348 for(i = 0; i < arity; ++i) {
350 ir_node *phi_pred = get_Phi_pred(value, i);
351 ir_node *cfgpred = get_Block_cfgpred(block, i);
353 copy_block = find_const(env, cfgpred, phi_pred);
354 if(copy_block == NULL)
357 /* copy duplicated nodes in copy_block and fix SSA */
358 copy_and_fix(env, block, copy_block, i);
360 if(copy_block == get_nodes_block(cfgpred)) {
361 env->cnst_pred = block;
365 // return now as we can't process more possibilities in 1 run
373 static ir_node *find_candidate(condeval_env_t *env, ir_node *jump,
376 ir_node *block = get_nodes_block(jump);
378 if(irn_visited(value)) {
381 mark_irn_visited(value);
383 if(is_Const(value)) {
384 tarval *tv = get_Const_tarval(value);
391 "> Found condition evaluation candidate %+F->%+F\n",
392 env->true_block, block
395 // adjust true_block to point directly towards our jump
396 add_pred(env->true_block, jump);
398 split_critical_edge(env->true_block, 0);
400 // we need a bigger visited nr when going back
408 // the phi has to be in the same block as the jump
409 if(get_nodes_block(value) != block)
412 arity = get_irn_arity(value);
413 for(i = 0; i < arity; ++i) {
415 ir_node *phi_pred = get_Phi_pred(value, i);
416 ir_node *cfgpred = get_Block_cfgpred(block, i);
418 copy_block = find_candidate(env, cfgpred, phi_pred);
419 if(copy_block == NULL)
422 /* copy duplicated nodes in copy_block and fix SSA */
423 copy_and_fix(env, block, copy_block, i);
425 if(copy_block == get_nodes_block(cfgpred)) {
426 env->cnst_pred = block;
430 // return now as we can't process more possibilities in 1 run
438 ir_node *cmp = get_Proj_pred(value);
442 left = get_Cmp_left(cmp);
443 right = get_Cmp_right(cmp);
444 pnc = get_Proj_proj(value);
446 /* we assume that the constant is on the right side, swap left/right
453 pnc = get_inversed_pnc(pnc);
459 if(get_nodes_block(left) != block) {
463 /* negate condition when we're looking for the false block */
464 if(env->tv == get_tarval_b_false()) {
465 pnc = get_negated_pnc(pnc, get_irn_mode(right));
468 // (recursively) look if a pred of a phi is a constant
472 return find_const(env, jump, left);
479 * Block-walker: searches for the following construct
481 * Const or Phi with constants
491 static void cond_eval(ir_node* block, void* data)
499 const ir_edge_t *edge, *next;
503 if(get_Block_n_cfgpreds(block) != 1)
506 projx = get_Block_cfgpred(block, 0);
509 assert(get_irn_mode(projx) == mode_X);
511 cond = get_Proj_pred(projx);
515 selector = get_Cond_selector(cond);
516 // TODO handle switch Conds
517 if (get_irn_mode(selector) != mode_b)
520 if (get_Proj_proj(projx) == pn_Cond_false) {
521 env.tv = get_tarval_b_false();
523 env.tv = get_tarval_b_true();
526 // (recursively) look if a pred of a phi is a constant
527 env.true_block = block;
528 inc_irg_visited(current_ir_graph);
529 env.visited_nr = get_irg_visited(current_ir_graph);
531 copy_block = find_candidate(&env, projx, selector);
532 if (copy_block == NULL)
535 /* we have to remove the edge towards the pred as the pred now
536 * jumps into the true_block. We also have to shorten phis
537 * in our block because of this */
539 cnst_pos = env.cnst_pos;
542 foreach_out_edge_safe(env.cnst_pred, edge, next) {
543 ir_node *node = get_edge_src_irn(edge);
546 set_Phi_pred(node, cnst_pos, bad);
549 set_Block_cfgpred(env.cnst_pred, cnst_pos, bad);
551 /* the graph is changed now */
555 void opt_cond_eval(ir_graph* irg)
559 FIRM_DBG_REGISTER(dbg, "firm.opt.condeval");
561 DB((dbg, LEVEL_1, "===> Performing condition evaluation on %+F\n", irg));
563 remove_critical_cf_edges(irg);
564 normalize_proj_nodes(irg);
567 set_using_irn_link(irg);
568 set_using_visited(irg);
573 irg_block_walk_graph(irg, cond_eval, NULL, &rerun);
578 /* control flow changed, some blocks may become dead */
579 set_irg_outs_inconsistent(irg);
580 set_irg_doms_inconsistent(irg);
581 set_irg_extblk_inconsistent(irg);
582 set_irg_loopinfo_inconsistent(irg);
585 clear_using_visited(irg);
586 clear_using_irn_link(irg);