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);
271 if (is_Bad(left) || is_Bad(right))
274 /* Do not create Confirm nodes for Cmp(Const, Const) constructs.
275 These are removed anyway */
276 if (is_Const(left) && is_Const(right))
279 /* try to place the constant on the right side for a Confirm */
280 if (is_Const(left) || is_SymConst(left)) {
286 rel = get_inversed_relation(rel);
290 * First case: both values are identical.
291 * replace the left one by the right (potentially const) one.
293 if (rel == ir_relation_equal) {
294 cond_block = get_Block_cfgpred_block(block, 0);
295 foreach_out_edge_safe(left, edge) {
296 ir_node *user = get_edge_src_irn(edge);
297 int pos = get_edge_src_pos(edge);
298 ir_node *blk = get_effective_use_block(user, pos);
300 if (block_dominates(block, blk)) {
302 * Ok, we found a usage of left in a block
303 * dominated by the branch block.
304 * We can replace the input with right.
306 set_irn_n(user, pos, right);
307 DBG_OPT_CONFIRM(left, right);
309 DB((dbg, LEVEL_2, "Replacing input %d of node %+F with %+F\n", pos, user, right));
312 } else if (block_dominates(blk, cond_block)
314 && get_irn_pinned(user) == op_pin_state_floats) {
316 * left == Const and we found a movable user of left in a
317 * dominator of the Cond block
319 foreach_out_edge_safe(user, user_edge) {
320 ir_node *usr_of_usr = get_edge_src_irn(user_edge);
321 int npos = get_edge_src_pos(user_edge);
322 ir_node *user_blk = get_effective_use_block(usr_of_usr, npos);
324 if (block_dominates(block, user_blk)) {
326 * The user of the user is dominated by our true/false
327 * block. So, create a copy of user WITH the constant
328 * replacing its pos'th input.
330 * This is always good for unop's and might be good
333 * If user has other user in the false/true block, code
334 * placement will move it down.
335 * If there are users in cond block or upper, we create
336 * "redundant ops", because one will have a const op,
337 * the other no const ...
339 ir_node *new_op = exact_copy(user);
340 set_nodes_block(new_op, block);
341 set_irn_n(new_op, pos, right);
342 set_irn_n(usr_of_usr, npos, new_op);
348 } else { /* not ir_relation_equal cases */
351 foreach_out_edge_safe(left, edge) {
352 ir_node *succ = get_edge_src_irn(edge);
353 int pos = get_edge_src_pos(edge);
354 ir_node *blk = get_effective_use_block(succ, pos);
356 if (block_dominates(block, blk)) {
358 * Ok, we found a usage of left in a block
359 * dominated by the branch block.
360 * We can replace the input with a Confirm(left, pnc, right).
363 c = new_r_Confirm(block, left, right, rel);
365 pos = get_edge_src_pos(edge);
366 set_irn_n(succ, pos, c);
367 DB((dbg, LEVEL_2, "Replacing input %d of node %+F with %+F\n", pos, succ, c));
369 env->num_confirms += 1;
373 if (! is_Const(right)) {
374 /* also construct inverse Confirms */
377 rel = get_inversed_relation(rel);
378 foreach_out_edge_safe(right, edge) {
379 ir_node *succ = get_edge_src_irn(edge);
386 pos = get_edge_src_pos(edge);
387 blk = get_effective_use_block(succ, pos);
389 if (block_dominates(block, blk)) {
391 * Ok, we found a usage of right in a block
392 * dominated by the branch block.
393 * We can replace the input with a Confirm(right, rel^-1, left).
396 rc = new_r_Confirm(block, right, left, rel);
398 pos = get_edge_src_pos(edge);
399 set_irn_n(succ, pos, rc);
400 DB((dbg, LEVEL_2, "Replacing input %d of node %+F with %+F\n", pos, succ, rc));
402 env->num_confirms += 1;
410 * Pre-block-walker: Called for every block to insert Confirm nodes
412 static void insert_Confirm_in_block(ir_node *block, void *data)
414 env_t *env = (env_t*) data;
419 * we can only handle blocks with only ONE control flow
422 if (get_Block_n_cfgpreds(block) != 1)
425 proj = get_Block_cfgpred(block, 0);
429 cond = get_Proj_pred(proj);
430 if (is_Switch(cond)) {
431 long proj_nr = get_Proj_proj(proj);
432 handle_case(block, cond, proj_nr, env);
433 } else if (is_Cond(cond)) {
434 ir_node *selector = get_Cond_selector(cond);
437 handle_modeb(block, selector, (pn_Cond) get_Proj_proj(proj), env);
439 if (! is_Cmp(selector))
442 rel = get_Cmp_relation(selector);
444 if (get_Proj_proj(proj) != pn_Cond_true) {
445 /* it's the false branch */
446 rel = get_negated_relation(rel);
448 DB((dbg, LEVEL_2, "At %+F using %+F Confirm %=\n", block, selector, rel));
450 handle_if(block, selector, rel, env);
455 * Checks if a node is a non-null Confirm.
457 static int is_non_null_Confirm(const ir_node *ptr)
460 if (! is_Confirm(ptr))
462 if (get_Confirm_relation(ptr) == ir_relation_less_greater) {
463 ir_node *bound = get_Confirm_bound(ptr);
465 if (is_Const(bound) && is_Const_null(bound))
468 ptr = get_Confirm_value(ptr);
471 * While a SymConst is not a Confirm, it is non-null
472 * anyway. This helps to reduce the number of
473 * constructed Confirms.
475 if (is_SymConst_addr_ent(ptr))
481 * The given pointer will be dereferenced, add non-null Confirms.
483 * @param ptr a node representing an address
484 * @param block the block of the dereferencing instruction
485 * @param env environment
487 static void insert_non_null(ir_node *ptr, ir_node *block, env_t *env)
491 foreach_out_edge_safe(ptr, edge) {
492 ir_node *succ = get_edge_src_irn(edge);
497 /* for now, we place a Confirm only in front of a Cmp */
501 pos = get_edge_src_pos(edge);
502 blk = get_effective_use_block(succ, pos);
504 if (block_dominates(block, blk)) {
506 * Ok, we found a usage of ptr in a block
507 * dominated by the Load/Store block.
508 * We can replace the input with a Confirm(ptr, !=, NULL).
511 ir_mode *mode = get_irn_mode(ptr);
512 ir_graph *irg = get_irn_irg(block);
513 c = new_r_Const(irg, get_mode_null(mode));
514 c = new_r_Confirm(block, ptr, c, ir_relation_less_greater);
517 set_irn_n(succ, pos, c);
518 DB((dbg, LEVEL_2, "Replacing input %d of node %+F with %+F\n", pos, succ, c));
520 env->num_non_null += 1;
521 env->num_confirms += 1;
527 * Pre-walker: Called for every node to insert Confirm nodes
529 static void insert_Confirm(ir_node *node, void *data)
532 env_t *env = (env_t*) data;
534 switch (get_irn_opcode(node)) {
536 insert_Confirm_in_block(node, env);
539 ptr = get_Load_ptr(node);
540 if (! is_non_null_Confirm(ptr))
541 insert_non_null(ptr, get_nodes_block(node), env);
544 ptr = get_Store_ptr(node);
545 if (! is_non_null_Confirm(ptr))
546 insert_non_null(ptr, get_nodes_block(node), env);
553 void construct_confirms(ir_graph *irg)
556 FIRM_DBG_REGISTER(dbg, "firm.ana.confirm");
558 assure_irg_properties(irg,
559 IR_GRAPH_PROPERTY_CONSISTENT_OUT_EDGES
560 | IR_GRAPH_PROPERTY_CONSISTENT_DOMINANCE
561 | IR_GRAPH_PROPERTY_NO_CRITICAL_EDGES);
563 assert(get_irg_pinned(irg) == op_pin_state_pinned &&
564 "Nodes must be placed to insert Confirms");
566 env.num_confirms = 0;
569 env.num_non_null = 0;
571 if (get_opt_global_null_ptr_elimination()) {
572 /* do global NULL test elimination */
573 irg_walk_graph(irg, insert_Confirm, NULL, &env);
575 /* now, visit all blocks and add Confirms where possible */
576 irg_block_walk_graph(irg, insert_Confirm_in_block, NULL, &env);
579 DB((dbg, LEVEL_1, "# Confirms inserted : %u\n", env.num_confirms));
580 DB((dbg, LEVEL_1, "# Const replacements: %u\n", env.num_consts));
581 DB((dbg, LEVEL_1, "# node equalities : %u\n", env.num_eq));
582 DB((dbg, LEVEL_1, "# non-null Confirms : %u\n", env.num_non_null));
584 confirm_irg_properties(irg, IR_GRAPH_PROPERTIES_CONTROL_FLOW);
587 ir_graph_pass_t *construct_confirms_pass(const char *name)
589 return def_graph_pass(name ? name : "confirm", construct_confirms);
592 static void remove_confirm(ir_node *n, void *env)
600 value = get_Confirm_value(n);
604 void remove_confirms(ir_graph *irg)
606 irg_walk_graph(irg, NULL, remove_confirm, NULL);
607 confirm_irg_properties(irg, IR_GRAPH_PROPERTIES_CONTROL_FLOW);
610 ir_graph_pass_t *remove_confirms_pass(const char *name)
612 return def_graph_pass(name ? name : "rem_confirm", remove_confirms);