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 * File name: ir/opt/cfopt.c
23 * Purpose: Partial condition evaluation
24 * Author: Christoph Mallon, Matthias Braun
25 * Created: 10. Sep. 2006
27 * Copyright: (c) 1998-2006 Universität Karlsruhe
44 #include "iredges_t.h"
49 DEBUG_ONLY(static firm_dbg_module_t *dbg);
52 * Add the new predecessor x to node node, which is either a Block or a Phi
54 static void add_pred(ir_node* node, ir_node* x)
60 assert(is_Block(node) || is_Phi(node));
62 n = get_irn_arity(node);
63 NEW_ARR_A(ir_node*, ins, n + 1);
64 for (i = 0; i < n; i++)
65 ins[i] = get_irn_n(node, i);
67 set_irn_in(node, n + 1, ins);
71 * Remove predecessor j from node, which is either a Block or a Phi
72 * returns true if only one predecessor is left
74 static int remove_pred(ir_node* node, int j)
78 assert(is_Block(node) || is_Phi(node));
80 n = get_irn_arity(node);
82 ir_node* pred = get_irn_n(node, 1 - j);
85 pred = get_nodes_block(pred);
86 edges_reroute(node, pred, current_ir_graph);
95 NEW_ARR_A(ir_node*, ins, n - 1);
96 for (i = 0; i < j; i++)
97 ins[i] = get_irn_n(node, i);
99 ins[i - 1] = get_irn_n(node, i);
101 set_irn_in(node, n - 1, ins);
106 static ir_node *search_def_and_create_phis(ir_node *block, ir_mode *mode)
114 // This is needed because we create bads sometimes
118 // already processed this block?
119 if(irn_visited(block)) {
120 ir_node *value = (ir_node*) get_irn_link(block);
124 // blocks with only 1 pred need no phi
125 n_cfgpreds = get_Block_n_cfgpreds(block);
126 if(n_cfgpreds == 1) {
127 ir_node *pred_block = get_Block_cfgpred_block(block, 0);
128 ir_node *value = search_def_and_create_phis(pred_block, mode);
130 set_irn_link(block, value);
131 mark_irn_visited(block);
136 NEW_ARR_A(ir_node*, in, n_cfgpreds);
137 for(i = 0; i < n_cfgpreds; ++i)
138 in[i] = new_Unknown(mode);
140 irg = get_irn_irg(block);
141 phi = new_r_Phi(irg, block, n_cfgpreds, in, mode);
142 set_irn_link(block, phi);
143 mark_irn_visited(block);
146 for(i = 0; i < n_cfgpreds; ++i) {
147 ir_node *pred_block = get_Block_cfgpred_block(block, i);
148 ir_node *pred_val = search_def_and_create_phis(pred_block, mode);
150 set_irn_n(phi, i, pred_val);
157 * Given a set of values this function constructs SSA-form for the users of the
158 * first value (the users are determined through the out-edges of the value).
159 * Uses the irn_visited flags. Works without using the dominance tree.
161 static void construct_ssa(ir_node * const *blocks, ir_node * const *vals, int n_vals)
166 const ir_edge_t *edge;
167 const ir_edge_t *next;
172 irg = get_irn_irg(vals[0]);
173 inc_irg_visited(irg);
175 mode = get_irn_mode(vals[0]);
176 for(i = 0; i < n_vals; ++i) {
177 ir_node *value = vals[i];
178 ir_node *value_block = blocks[i];
180 assert(get_irn_mode(value) == mode);
182 set_irn_link(value_block, value);
183 mark_irn_visited(value_block);
186 // Only fix the users of the first, i.e. the original node
189 // this can happen when fixing phi preds, we mustn't fix the users
190 if(get_nodes_block(value) != blocks[0]) return;
192 foreach_out_edge_safe(value, edge, next) {
193 ir_node *user = get_edge_src_irn(edge);
194 int j = get_edge_src_pos(edge);
195 ir_node *user_block = get_nodes_block(user);
199 if(get_irn_op(user) == op_End)
202 DB((dbg, LEVEL_3, ">>> Fixing user %+F (pred %d == %+F)\n", user, j, get_irn_n(user, j)));
205 ir_node *pred_block = get_Block_cfgpred_block(user_block, j);
206 newval = search_def_and_create_phis(pred_block, mode);
208 newval = search_def_and_create_phis(user_block, mode);
211 // don't fix newly created phis from the SSA construction
212 if (newval != user) {
213 DB((dbg, LEVEL_4, ">>>> Setting input %d of %+F to %+F\n", j, user, newval));
214 set_irn_n(user, j, newval);
219 static void split_critical_edge(ir_node *block, int pos) {
220 ir_graph *irg = get_irn_irg(block);
225 in[0] = get_Block_cfgpred(block, pos);
226 new_block = new_r_Block(irg, 1, in);
227 new_jmp = new_r_Jmp(irg, new_block);
228 set_Block_cfgpred(block, pos, new_jmp);
231 typedef struct _condeval_env_t {
235 unsigned long visited_nr;
237 ir_node *cnst_pred; /**< the block before the constant */
238 int cnst_pos; /**< the pos to the constant block (needed to kill that edge later) */
241 static void copy_and_fix(ir_node *block, ir_node *copy_block, int j, const condeval_env_t *env) {
242 const ir_edge_t *edge;
244 /* Look at all nodes in the cond_block and copy them into pred */
245 foreach_out_edge(block, edge) {
246 ir_node *node = get_edge_src_irn(edge);
248 ir_mode *mode = get_irn_mode(node);
250 /* ignore control flow */
253 /* we may not copy mode_b nodes, because this could produce phi with mode_bs which can't
254 be handled in all backends. Instead we duplicate the node and move it to it's users */
255 if (mode == mode_b) {
256 const ir_edge_t *edge, *next;
260 assert(is_Proj(node));
262 pred = get_Proj_pred(node);
263 pn = get_Proj_proj(node);
265 foreach_out_edge_safe(node, edge, next) {
267 ir_node *user = get_edge_src_irn(edge);
268 int pos = get_edge_src_pos(edge);
269 ir_node *user_block = get_nodes_block(user);
271 if(user_block == block)
274 cmp_copy = exact_copy(pred);
275 set_nodes_block(cmp_copy, user_block);
276 copy = new_r_Proj(current_ir_graph, user_block, cmp_copy, mode_b, pn);
277 set_irn_n(user, pos, copy);
282 /* we can evaluate Phis right now, all other nodes get copied */
284 copy = get_Phi_pred(node, j);
286 copy = exact_copy(node);
287 set_nodes_block(copy, copy_block);
290 set_irn_link(node, copy);
291 set_irn_visited(node, env->visited_nr);
293 /* we might hit values in blocks that have already been processed by a
294 * recursive find_phi_with_const call */
295 assert(get_irn_visited(copy) <= env->visited_nr);
296 if(get_irn_visited(copy) >= env->visited_nr) {
297 ir_node *prev_copy = get_irn_link(copy);
298 if(prev_copy != NULL)
299 set_irn_link(node, prev_copy);
303 /* fix data-flow (and reconstruct SSA if needed) */
304 foreach_out_edge(block, edge) {
307 ir_node *node = get_edge_src_irn(edge);
308 ir_mode *mode = get_irn_mode(node);
315 DB((dbg, LEVEL_2, ">> Fixing users of %+F\n", node));
319 blocks[1] = copy_block;
320 vals[1] = get_irn_link(node);
321 construct_ssa(blocks, vals, 2);
325 static int eval_cmp(pn_Cmp pnc, tarval *tv1, tarval *tv2) {
326 pn_Cmp cmp_result = tarval_cmp(tv1, tv2);
328 // does the compare evaluate to true?
329 if(cmp_result == pn_Cmp_False)
331 if((cmp_result & pnc) != cmp_result)
337 static ir_node *find_phi_with_const(ir_node *jump, ir_node *value, condeval_env_t *env) {
338 ir_node *block = get_nodes_block(jump);
340 if(irn_visited(value))
342 mark_irn_visited(value);
344 if(is_Const(value)) {
345 tarval *tv_const = get_Const_tarval(env->cnst);
346 tarval *tv = get_Const_tarval(value);
348 if(!eval_cmp(env->pnc, tv, tv_const))
353 "> Found condition evaluation candidate %+F->%+F\n",
354 env->true_block, block
357 // adjust true_block to point directly towards our jump
358 add_pred(env->true_block, jump);
360 split_critical_edge(env->true_block, 0);
362 // we need a bigger visited nr when going back
371 // the phi has to be in the same block as the jump
372 if(get_nodes_block(value) != block)
375 arity = get_irn_arity(value);
376 for(i = 0; i < arity; ++i) {
378 ir_node *phi_pred = get_Phi_pred(value, i);
379 ir_node *cfgpred = get_Block_cfgpred(block, i);
381 copy_block = find_phi_with_const(cfgpred, phi_pred, env);
382 if(copy_block == NULL)
385 /* copy duplicated nodes in copy_block and fix SSA */
386 copy_and_fix(block, copy_block, i, env);
388 if(copy_block == get_nodes_block(cfgpred)) {
389 env->cnst_pred = block;
393 // return now as we can't process more possibilities in 1 run
403 * Block-walker: searchs for the following construct
405 * Const or Phi with constants
415 static void cond_eval(ir_node* block, void* data)
419 ir_graph *irg = current_ir_graph;
430 if(get_Block_n_cfgpreds(block) != 1)
433 projx = get_Block_cfgpred(block, 0);
436 assert(get_irn_mode(projx) == mode_X);
438 cond = get_Proj_pred(projx);
442 pred = get_Cond_selector(cond);
443 // TODO handle switches
444 if (get_irn_mode(pred) != mode_b)
448 pnc = get_Proj_proj(pred);
450 cmp = get_Proj_pred(pred);
453 left = get_Cmp_left(cmp);
454 right = get_Cmp_right(cmp);
455 assert(get_irn_mode(left) == get_irn_mode(right));
457 /* we assume that the cond_block is the true case */
458 if (get_Proj_proj(projx) == pn_Cond_false) {
459 pnc = get_negated_pnc(pnc, get_irn_mode(left));
462 /* we assume that the constant is on the right side, swap left/right
469 pnc = get_inversed_pnc(pnc);
475 cond_block = get_nodes_block(cond);
477 // special case: comparing a constant with a constant
479 tarval *tv1 = get_Const_tarval(left);
480 tarval *tv2 = get_Const_tarval(right);
482 if(eval_cmp(pnc, tv1, tv2)) {
483 pred = new_r_Jmp(irg, cond_block);
487 set_Block_cfgpred(block, 0, pred);
489 set_irg_doms_inconsistent(irg);
490 set_irg_extblk_inconsistent(irg);
491 set_irg_loopinfo_inconsistent(irg);
493 if(get_nodes_block(left) != cond_block)
496 // (recursively) look if a pred of a phi is a constant
497 env.true_block = block;
500 inc_irg_visited(current_ir_graph);
501 env.visited_nr = get_irg_visited(irg);
503 copy_block = find_phi_with_const(projx, left, &env);
505 if(copy_block != NULL) {
506 /* we have to remove the edge towards the pred as the pred now
507 * jumps into the true_block. We also have to shorten phis
508 * in our block because of this */
509 const ir_edge_t *edge, *next;
512 foreach_out_edge_safe(env.cnst_pred, edge, next) {
513 ir_node *node = get_edge_src_irn(edge);
516 remove_pred(node, env.cnst_pos);
519 remove_pred(env.cnst_pred, env.cnst_pos);
521 // the graph is changed now
523 set_irg_doms_inconsistent(irg);
524 set_irg_extblk_inconsistent(irg);
525 set_irg_loopinfo_inconsistent(irg);
530 void opt_cond_eval(ir_graph* irg)
534 FIRM_DBG_REGISTER(dbg, "firm.opt.condeval");
536 DB((dbg, LEVEL_1, "===> Performing condition evaluation on %+F\n", irg));
539 remove_critical_cf_edges(irg);
541 normalize_proj_nodes(irg);
543 set_using_irn_link(irg);
544 set_using_visited(irg);
548 irg_block_walk_graph(irg, cond_eval, NULL, &changed);
551 clear_using_visited(irg);
552 clear_using_irn_link(irg);