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 Construction of Confirm nodes
23 * @author Michael Beck
28 #include "irconsconfirm.h"
30 #include "irgraph_t.h"
34 #include "iropt_dbg.h"
35 #include "iredges_t.h"
49 typedef struct env_t {
50 unsigned num_confirms; /**< Number of inserted Confirm nodes. */
51 unsigned num_consts; /**< Number of constants placed. */
52 unsigned num_eq; /**< Number of equalities placed. */
53 unsigned num_non_null; /**< Number of non-null Confirms. */
56 /** The debug handle. */
57 DEBUG_ONLY(static firm_dbg_module_t *dbg;)
60 * Return the effective use block of a node and its predecessor on
63 * @param node the node
64 * @param pos the position of the used input
66 * This handles correctly Phi nodes.
68 static ir_node *get_effective_use_block(ir_node *node, int pos)
71 /* the effective use of a Phi argument is in its predecessor block */
72 node = get_nodes_block(node);
73 return get_Block_cfgpred_block(node, pos);
75 return get_nodes_block(node);
78 static ir_node *get_case_value(ir_node *switchn, long pn)
80 ir_graph *irg = get_irn_irg(switchn);
81 const ir_switch_table *table = get_Switch_table(switchn);
82 size_t n_entries = ir_switch_table_get_n_entries(table);
83 ir_tarval *val = NULL;
85 for (e = 0; e < n_entries; ++e) {
86 const ir_switch_table_entry *entry
87 = ir_switch_table_get_entry_const(table, e);
90 /* multiple matching entries gets too complicated for a single
94 /* case ranges are too complicated too */
95 if (entry->min != entry->max)
100 return new_r_Const(irg, val);
104 * Handle a CASE-branch.
106 * Branch labels are a simple case. We can replace the value
107 * by a Const with the branch label.
109 static void handle_case(ir_node *block, ir_node *switchn, long pn, env_t *env)
112 ir_node *selector = get_Switch_selector(switchn);
114 /* we can't do usefull things with the default label */
115 if (pn == pn_Switch_default)
118 foreach_out_edge_safe(selector, edge) {
119 ir_node *succ = get_edge_src_irn(edge);
120 int pos = get_edge_src_pos(edge);
121 ir_node *blk = get_effective_use_block(succ, pos);
123 if (block_dominates(block, blk)) {
125 * Ok, we found a user of irn that is placed
126 * in a block dominated by the branch block.
127 * We can replace the input with the Constant
131 c = get_case_value(switchn, pn);
133 set_irn_n(succ, pos, c);
134 DBG_OPT_CONFIRM_C(selector, c);
135 DB((dbg, LEVEL_2, "Replacing input %d of node %+F with %+F\n", pos, succ, c));
137 env->num_consts += 1;
143 * Handle a mode_b input of Cond nodes.
145 * @param block the block which is entered by the branch
146 * @param selector the mode_b node expressing the branch condition
147 * @param pnc the true/false condition branch
148 * @param env statistical environment
150 static void handle_modeb(ir_node *block, ir_node *selector, pn_Cond pnc, env_t *env)
152 ir_node *cond, *old, *other_blk = NULL, *con = NULL;
153 ir_node *c_b = NULL, *c_o = NULL;
155 foreach_out_edge_safe(selector, edge) {
156 ir_node *user = get_edge_src_irn(edge);
157 int pos = get_edge_src_pos(edge);
158 ir_node *user_blk = get_effective_use_block(user, pos);
160 if (block_dominates(block, user_blk)) {
162 * Ok, we found a usage of selector in a block
163 * dominated by the branch block.
164 * We can replace the input with true/false.
167 ir_graph *irg = get_irn_irg(block);
168 con = new_r_Const(irg, pnc == pn_Cond_true ? tarval_b_true : tarval_b_false);
170 old = get_irn_n(user, pos);
171 set_irn_n(user, pos, con);
172 DBG_OPT_CONFIRM_C(old, con);
174 DB((dbg, LEVEL_2, "Replacing input %d of node %+F with %+F\n", pos, user, con));
176 env->num_consts += 1;
180 /* get the other block */
181 if (other_blk == NULL) {
182 /* we have already tested, that block has only ONE Cond predecessor */
183 cond = get_Proj_pred(get_Block_cfgpred(block, 0));
184 foreach_out_edge(cond, edge) {
185 ir_node *proj = get_edge_src_irn(edge);
186 if (get_Proj_proj(proj) == (long)pnc)
188 edge = get_irn_out_edge_first(proj);
189 other_blk = get_edge_src_irn(edge);
195 * Note the special case here: if block is a then, there might be no else
196 * block. In that case the other_block is the user_blk itself and pred_block
197 * is the cond_block ...
199 * Best would be to introduce a block here, removing this critical edge.
200 * For some reasons I cannot repair dominance here, so I have to remove
201 * ALL critical edges...
202 * FIXME: This should not be needed if we could repair dominance ...
206 n = get_Block_n_cfgpreds(user_blk);
209 * We have found a user in a non-dominated block:
210 * check, if all its block predecessors are dominated.
211 * If yes, place a Phi.
213 for (i = n - 1; i >= 0; --i) {
214 ir_node *pred_blk = get_Block_cfgpred_block(user_blk, i);
216 if (!block_dominates(block, pred_blk) &&
217 !block_dominates(other_blk, pred_blk)) {
218 /* can't do anything */
225 NEW_ARR_A(ir_node *, in, n);
226 /* ok, ALL predecessors are either dominated by block OR other block */
228 ir_graph *irg = get_irn_irg(block);
229 ir_node *c_true = new_r_Const(irg, tarval_b_true);
230 ir_node *c_false = new_r_Const(irg, tarval_b_false);
231 env->num_consts += 2;
232 if (pnc == pn_Cond_true) {
240 for (i = n - 1; i >= 0; --i) {
241 ir_node *pred_blk = get_Block_cfgpred_block(user_blk, i);
243 if (block_dominates(block, pred_blk))
248 phi = new_r_Phi(user_blk, n, in, mode_b);
249 set_irn_n(user, pos, phi);
257 * Handle an IF-branch.
259 * @param block the block which is entered by the branch
260 * @param cmp the Cmp node expressing the branch condition
261 * @param rel the Compare relation for taking this branch
262 * @param env statistical environment
264 static void handle_if(ir_node *block, ir_node *cmp, ir_relation rel, env_t *env)
266 ir_node *left = get_Cmp_left(cmp);
267 ir_node *right = get_Cmp_right(cmp);
272 if (is_Bad(left) || is_Bad(right))
275 op = get_irn_op(left);
277 /* Do not create Confirm nodes for Cmp(Const, Const) constructs.
278 These are removed anyway */
279 if (op == op_Const && is_Const(right))
282 /* try to place the constant on the right side for a Confirm */
283 if (op == op_Const || op == op_SymConst) {
289 rel = get_inversed_relation(rel);
293 * First case: both values are identical.
294 * replace the left one by the right (potentially const) one.
296 if (rel == ir_relation_equal) {
297 cond_block = get_Block_cfgpred_block(block, 0);
298 foreach_out_edge_safe(left, edge) {
299 ir_node *user = get_edge_src_irn(edge);
300 int pos = get_edge_src_pos(edge);
301 ir_node *blk = get_effective_use_block(user, pos);
303 if (block_dominates(block, blk)) {
305 * Ok, we found a usage of left in a block
306 * dominated by the branch block.
307 * We can replace the input with right.
309 set_irn_n(user, pos, right);
310 DBG_OPT_CONFIRM(left, right);
312 DB((dbg, LEVEL_2, "Replacing input %d of node %+F with %+F\n", pos, user, right));
315 } else if (block_dominates(blk, cond_block)
317 && get_irn_pinned(user) == op_pin_state_floats) {
319 * left == Const and we found a movable user of left in a
320 * dominator of the Cond block
322 foreach_out_edge_safe(user, user_edge) {
323 ir_node *usr_of_usr = get_edge_src_irn(user_edge);
324 int npos = get_edge_src_pos(user_edge);
325 ir_node *user_blk = get_effective_use_block(usr_of_usr, npos);
327 if (block_dominates(block, user_blk)) {
329 * The user of the user is dominated by our true/false
330 * block. So, create a copy of user WITH the constant
331 * replacing its pos'th input.
333 * This is always good for unop's and might be good
336 * If user has other user in the false/true block, code
337 * placement will move it down.
338 * If there are users in cond block or upper, we create
339 * "redundant ops", because one will have a const op,
340 * the other no const ...
342 ir_node *new_op = exact_copy(user);
343 set_nodes_block(new_op, block);
344 set_irn_n(new_op, pos, right);
345 set_irn_n(usr_of_usr, npos, new_op);
351 } else { /* not ir_relation_equal cases */
354 foreach_out_edge_safe(left, edge) {
355 ir_node *succ = get_edge_src_irn(edge);
356 int pos = get_edge_src_pos(edge);
357 ir_node *blk = get_effective_use_block(succ, pos);
359 if (block_dominates(block, blk)) {
361 * Ok, we found a usage of left in a block
362 * dominated by the branch block.
363 * We can replace the input with a Confirm(left, pnc, right).
366 c = new_r_Confirm(block, left, right, rel);
368 pos = get_edge_src_pos(edge);
369 set_irn_n(succ, pos, c);
370 DB((dbg, LEVEL_2, "Replacing input %d of node %+F with %+F\n", pos, succ, c));
372 env->num_confirms += 1;
376 if (! is_Const(right)) {
377 /* also construct inverse Confirms */
380 rel = get_inversed_relation(rel);
381 foreach_out_edge_safe(right, edge) {
382 ir_node *succ = get_edge_src_irn(edge);
389 pos = get_edge_src_pos(edge);
390 blk = get_effective_use_block(succ, pos);
392 if (block_dominates(block, blk)) {
394 * Ok, we found a usage of right in a block
395 * dominated by the branch block.
396 * We can replace the input with a Confirm(right, rel^-1, left).
399 rc = new_r_Confirm(block, right, left, rel);
401 pos = get_edge_src_pos(edge);
402 set_irn_n(succ, pos, rc);
403 DB((dbg, LEVEL_2, "Replacing input %d of node %+F with %+F\n", pos, succ, rc));
405 env->num_confirms += 1;
413 * Pre-block-walker: Called for every block to insert Confirm nodes
415 static void insert_Confirm_in_block(ir_node *block, void *data)
417 env_t *env = (env_t*) data;
422 * we can only handle blocks with only ONE control flow
425 if (get_Block_n_cfgpreds(block) != 1)
428 proj = get_Block_cfgpred(block, 0);
432 cond = get_Proj_pred(proj);
433 if (is_Switch(cond)) {
434 long proj_nr = get_Proj_proj(proj);
435 handle_case(block, cond, proj_nr, env);
436 } else if (is_Cond(cond)) {
437 ir_node *selector = get_Cond_selector(cond);
440 handle_modeb(block, selector, (pn_Cond) get_Proj_proj(proj), env);
442 if (! is_Cmp(selector))
445 rel = get_Cmp_relation(selector);
447 if (get_Proj_proj(proj) != pn_Cond_true) {
448 /* it's the false branch */
449 rel = get_negated_relation(rel);
451 DB((dbg, LEVEL_2, "At %+F using %+F Confirm %=\n", block, selector, rel));
453 handle_if(block, selector, rel, env);
458 * Checks if a node is a non-null Confirm.
460 static int is_non_null_Confirm(const ir_node *ptr)
463 if (! is_Confirm(ptr))
465 if (get_Confirm_relation(ptr) == ir_relation_less_greater) {
466 ir_node *bound = get_Confirm_bound(ptr);
468 if (is_Const(bound) && is_Const_null(bound))
471 ptr = get_Confirm_value(ptr);
474 * While a SymConst is not a Confirm, it is non-null
475 * anyway. This helps to reduce the number of
476 * constructed Confirms.
478 if (is_SymConst_addr_ent(ptr))
484 * The given pointer will be dereferenced, add non-null Confirms.
486 * @param ptr a node representing an address
487 * @param block the block of the dereferencing instruction
488 * @param env environment
490 static void insert_non_null(ir_node *ptr, ir_node *block, env_t *env)
494 foreach_out_edge_safe(ptr, edge) {
495 ir_node *succ = get_edge_src_irn(edge);
500 /* for now, we place a Confirm only in front of a Cmp */
504 pos = get_edge_src_pos(edge);
505 blk = get_effective_use_block(succ, pos);
507 if (block_dominates(block, blk)) {
509 * Ok, we found a usage of ptr in a block
510 * dominated by the Load/Store block.
511 * We can replace the input with a Confirm(ptr, !=, NULL).
514 ir_mode *mode = get_irn_mode(ptr);
515 ir_graph *irg = get_irn_irg(block);
516 c = new_r_Const(irg, get_mode_null(mode));
517 c = new_r_Confirm(block, ptr, c, ir_relation_less_greater);
520 set_irn_n(succ, pos, c);
521 DB((dbg, LEVEL_2, "Replacing input %d of node %+F with %+F\n", pos, succ, c));
523 env->num_non_null += 1;
524 env->num_confirms += 1;
530 * Pre-walker: Called for every node to insert Confirm nodes
532 static void insert_Confirm(ir_node *node, void *data)
535 env_t *env = (env_t*) data;
537 switch (get_irn_opcode(node)) {
539 insert_Confirm_in_block(node, env);
542 ptr = get_Load_ptr(node);
543 if (! is_non_null_Confirm(ptr))
544 insert_non_null(ptr, get_nodes_block(node), env);
547 ptr = get_Store_ptr(node);
548 if (! is_non_null_Confirm(ptr))
549 insert_non_null(ptr, get_nodes_block(node), env);
556 void construct_confirms(ir_graph *irg)
559 FIRM_DBG_REGISTER(dbg, "firm.ana.confirm");
561 assure_irg_properties(irg,
562 IR_GRAPH_PROPERTY_CONSISTENT_OUT_EDGES
563 | IR_GRAPH_PROPERTY_CONSISTENT_DOMINANCE
564 | IR_GRAPH_PROPERTY_NO_CRITICAL_EDGES);
566 assert(get_irg_pinned(irg) == op_pin_state_pinned &&
567 "Nodes must be placed to insert Confirms");
569 env.num_confirms = 0;
572 env.num_non_null = 0;
574 if (get_opt_global_null_ptr_elimination()) {
575 /* do global NULL test elimination */
576 irg_walk_graph(irg, insert_Confirm, NULL, &env);
578 /* now, visit all blocks and add Confirms where possible */
579 irg_block_walk_graph(irg, insert_Confirm_in_block, NULL, &env);
582 DB((dbg, LEVEL_1, "# Confirms inserted : %u\n", env.num_confirms));
583 DB((dbg, LEVEL_1, "# Const replacements: %u\n", env.num_consts));
584 DB((dbg, LEVEL_1, "# node equalities : %u\n", env.num_eq));
585 DB((dbg, LEVEL_1, "# non-null Confirms : %u\n", env.num_non_null));
587 confirm_irg_properties(irg, IR_GRAPH_PROPERTIES_CONTROL_FLOW);
590 ir_graph_pass_t *construct_confirms_pass(const char *name)
592 return def_graph_pass(name ? name : "confirm", construct_confirms);
595 static void remove_confirm(ir_node *n, void *env)
603 value = get_Confirm_value(n);
607 void remove_confirms(ir_graph *irg)
609 irg_walk_graph(irg, NULL, remove_confirm, NULL);
610 confirm_irg_properties(irg, IR_GRAPH_PROPERTIES_CONTROL_FLOW);
613 ir_graph_pass_t *remove_confirms_pass(const char *name)
615 return def_graph_pass(name ? name : "rem_confirm", remove_confirms);