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);
113 const ir_edge_t *edge;
114 const ir_edge_t *next;
116 /* we can't do usefull things with the default label */
117 if (pn == pn_Switch_default)
120 foreach_out_edge_safe(selector, edge, next) {
121 ir_node *succ = get_edge_src_irn(edge);
122 int pos = get_edge_src_pos(edge);
123 ir_node *blk = get_effective_use_block(succ, pos);
125 if (block_dominates(block, blk)) {
127 * Ok, we found a user of irn that is placed
128 * in a block dominated by the branch block.
129 * We can replace the input with the Constant
133 c = get_case_value(switchn, pn);
135 set_irn_n(succ, pos, c);
136 DBG_OPT_CONFIRM_C(selector, c);
137 DB((dbg, LEVEL_2, "Replacing input %d of node %+F with %+F\n", pos, succ, c));
139 env->num_consts += 1;
145 * Handle a mode_b input of Cond nodes.
147 * @param block the block which is entered by the branch
148 * @param selector the mode_b node expressing the branch condition
149 * @param pnc the true/false condition branch
150 * @param env statistical environment
152 static void handle_modeb(ir_node *block, ir_node *selector, pn_Cond pnc, env_t *env)
154 ir_node *cond, *old, *other_blk = NULL, *con = NULL;
155 ir_node *c_b = NULL, *c_o = NULL;
156 const ir_edge_t *edge, *next;
158 for (edge = get_irn_out_edge_first(selector); edge; edge = next) {
159 ir_node *user = get_edge_src_irn(edge);
160 int pos = get_edge_src_pos(edge);
161 ir_node *user_blk = get_effective_use_block(user, pos);
163 next = get_irn_out_edge_next(selector, edge);
164 if (block_dominates(block, user_blk)) {
166 * Ok, we found a usage of selector in a block
167 * dominated by the branch block.
168 * We can replace the input with true/false.
171 ir_graph *irg = get_irn_irg(block);
172 con = new_r_Const(irg, pnc == pn_Cond_true ? tarval_b_true : tarval_b_false);
174 old = get_irn_n(user, pos);
175 set_irn_n(user, pos, con);
176 DBG_OPT_CONFIRM_C(old, con);
178 DB((dbg, LEVEL_2, "Replacing input %d of node %+F with %+F\n", pos, user, con));
180 env->num_consts += 1;
184 /* get the other block */
185 if (other_blk == NULL) {
186 /* we have already tested, that block has only ONE Cond predecessor */
187 cond = get_Proj_pred(get_Block_cfgpred(block, 0));
188 foreach_out_edge(cond, edge) {
189 ir_node *proj = get_edge_src_irn(edge);
190 if (get_Proj_proj(proj) == (long)pnc)
192 edge = get_irn_out_edge_first(proj);
193 other_blk = get_edge_src_irn(edge);
199 * Note the special case here: if block is a then, there might be no else
200 * block. In that case the other_block is the user_blk itself and pred_block
201 * is the cond_block ...
203 * Best would be to introduce a block here, removing this critical edge.
204 * For some reasons I cannot repair dominance here, so I have to remove
205 * ALL critical edges...
206 * FIXME: This should not be needed if we could repair dominance ...
210 n = get_Block_n_cfgpreds(user_blk);
213 * We have found a user in a non-dominated block:
214 * check, if all its block predecessors are dominated.
215 * If yes, place a Phi.
217 for (i = n - 1; i >= 0; --i) {
218 ir_node *pred_blk = get_Block_cfgpred_block(user_blk, i);
220 if (!block_dominates(block, pred_blk) &&
221 !block_dominates(other_blk, pred_blk)) {
222 /* can't do anything */
229 NEW_ARR_A(ir_node *, in, n);
230 /* ok, ALL predecessors are either dominated by block OR other block */
232 ir_graph *irg = get_irn_irg(block);
233 ir_node *c_true = new_r_Const(irg, tarval_b_true);
234 ir_node *c_false = new_r_Const(irg, tarval_b_false);
235 env->num_consts += 2;
236 if (pnc == pn_Cond_true) {
244 for (i = n - 1; i >= 0; --i) {
245 ir_node *pred_blk = get_Block_cfgpred_block(user_blk, i);
247 if (block_dominates(block, pred_blk))
252 phi = new_r_Phi(user_blk, n, in, mode_b);
253 set_irn_n(user, pos, phi);
261 * Handle an IF-branch.
263 * @param block the block which is entered by the branch
264 * @param cmp the Cmp node expressing the branch condition
265 * @param rel the Compare relation for taking this branch
266 * @param env statistical environment
268 static void handle_if(ir_node *block, ir_node *cmp, ir_relation rel, env_t *env)
270 ir_node *left = get_Cmp_left(cmp);
271 ir_node *right = get_Cmp_right(cmp);
274 const ir_edge_t *edge, *next;
277 if (is_Bad(left) || is_Bad(right))
280 op = get_irn_op(left);
282 /* Do not create Confirm nodes for Cmp(Const, Const) constructs.
283 These are removed anyway */
284 if (op == op_Const && is_Const(right))
287 /* try to place the constant on the right side for a Confirm */
288 if (op == op_Const || op == op_SymConst) {
294 rel = get_inversed_relation(rel);
298 * First case: both values are identical.
299 * replace the left one by the right (potentially const) one.
301 if (rel == ir_relation_equal) {
302 cond_block = get_Block_cfgpred_block(block, 0);
303 for (edge = get_irn_out_edge_first(left); edge; edge = next) {
304 ir_node *user = get_edge_src_irn(edge);
305 int pos = get_edge_src_pos(edge);
306 ir_node *blk = get_effective_use_block(user, pos);
308 next = get_irn_out_edge_next(left, edge);
309 if (block_dominates(block, blk)) {
311 * Ok, we found a usage of left in a block
312 * dominated by the branch block.
313 * We can replace the input with right.
315 set_irn_n(user, pos, right);
316 DBG_OPT_CONFIRM(left, right);
318 DB((dbg, LEVEL_2, "Replacing input %d of node %+F with %+F\n", pos, user, right));
321 } else if (block_dominates(blk, cond_block)
323 && get_irn_pinned(user) == op_pin_state_floats) {
325 * left == Const and we found a movable user of left in a
326 * dominator of the Cond block
328 const ir_edge_t *user_edge;
329 const ir_edge_t *user_next;
330 foreach_out_edge_safe(user, user_edge, user_next) {
331 ir_node *usr_of_usr = get_edge_src_irn(user_edge);
332 int npos = get_edge_src_pos(user_edge);
333 ir_node *user_blk = get_effective_use_block(usr_of_usr, npos);
335 if (block_dominates(block, user_blk)) {
337 * The user of the user is dominated by our true/false
338 * block. So, create a copy of user WITH the constant
339 * replacing its pos'th input.
341 * This is always good for unop's and might be good
344 * If user has other user in the false/true block, code
345 * placement will move it down.
346 * If there are users in cond block or upper, we create
347 * "redundant ops", because one will have a const op,
348 * the other no const ...
350 ir_node *new_op = exact_copy(user);
351 set_nodes_block(new_op, block);
352 set_irn_n(new_op, pos, right);
353 set_irn_n(usr_of_usr, npos, new_op);
359 } else { /* not ir_relation_equal cases */
362 foreach_out_edge_safe(left, edge, next) {
363 ir_node *succ = get_edge_src_irn(edge);
364 int pos = get_edge_src_pos(edge);
365 ir_node *blk = get_effective_use_block(succ, pos);
367 if (block_dominates(block, blk)) {
369 * Ok, we found a usage of left in a block
370 * dominated by the branch block.
371 * We can replace the input with a Confirm(left, pnc, right).
374 c = new_r_Confirm(block, left, right, rel);
376 pos = get_edge_src_pos(edge);
377 set_irn_n(succ, pos, c);
378 DB((dbg, LEVEL_2, "Replacing input %d of node %+F with %+F\n", pos, succ, c));
380 env->num_confirms += 1;
384 if (! is_Const(right)) {
385 /* also construct inverse Confirms */
388 rel = get_inversed_relation(rel);
389 foreach_out_edge_safe(right, edge, next) {
390 ir_node *succ = get_edge_src_irn(edge);
397 pos = get_edge_src_pos(edge);
398 blk = get_effective_use_block(succ, pos);
400 if (block_dominates(block, blk)) {
402 * Ok, we found a usage of right in a block
403 * dominated by the branch block.
404 * We can replace the input with a Confirm(right, rel^-1, left).
407 rc = new_r_Confirm(block, right, left, rel);
409 pos = get_edge_src_pos(edge);
410 set_irn_n(succ, pos, rc);
411 DB((dbg, LEVEL_2, "Replacing input %d of node %+F with %+F\n", pos, succ, rc));
413 env->num_confirms += 1;
421 * Pre-block-walker: Called for every block to insert Confirm nodes
423 static void insert_Confirm_in_block(ir_node *block, void *data)
425 env_t *env = (env_t*) data;
430 * we can only handle blocks with only ONE control flow
433 if (get_Block_n_cfgpreds(block) != 1)
436 proj = get_Block_cfgpred(block, 0);
440 cond = get_Proj_pred(proj);
441 if (is_Switch(cond)) {
442 long proj_nr = get_Proj_proj(proj);
443 handle_case(block, cond, proj_nr, env);
444 } else if (is_Const(cond)) {
445 ir_node *selector = get_Cond_selector(cond);
448 handle_modeb(block, selector, (pn_Cond) get_Proj_proj(proj), env);
450 if (! is_Cmp(selector))
453 rel = get_Cmp_relation(selector);
455 if (get_Proj_proj(proj) != pn_Cond_true) {
456 /* it's the false branch */
457 rel = get_negated_relation(rel);
459 DB((dbg, LEVEL_2, "At %+F using %+F Confirm %=\n", block, selector, rel));
461 handle_if(block, selector, rel, env);
466 * Checks if a node is a non-null Confirm.
468 static int is_non_null_Confirm(const ir_node *ptr)
471 if (! is_Confirm(ptr))
473 if (get_Confirm_relation(ptr) == ir_relation_less_greater) {
474 ir_node *bound = get_Confirm_bound(ptr);
476 if (is_Const(bound) && is_Const_null(bound))
479 ptr = get_Confirm_value(ptr);
482 * While a SymConst is not a Confirm, it is non-null
483 * anyway. This helps to reduce the number of
484 * constructed Confirms.
486 if (is_SymConst_addr_ent(ptr))
492 * The given pointer will be dereferenced, add non-null Confirms.
494 * @param ptr a node representing an address
495 * @param block the block of the dereferencing instruction
496 * @param env environment
498 static void insert_non_null(ir_node *ptr, ir_node *block, env_t *env)
500 const ir_edge_t *edge, *next;
503 foreach_out_edge_safe(ptr, edge, next) {
504 ir_node *succ = get_edge_src_irn(edge);
509 /* for now, we place a Confirm only in front of a Cmp */
513 pos = get_edge_src_pos(edge);
514 blk = get_effective_use_block(succ, pos);
516 if (block_dominates(block, blk)) {
518 * Ok, we found a usage of ptr in a block
519 * dominated by the Load/Store block.
520 * We can replace the input with a Confirm(ptr, !=, NULL).
523 ir_mode *mode = get_irn_mode(ptr);
524 ir_graph *irg = get_irn_irg(block);
525 c = new_r_Const(irg, get_mode_null(mode));
526 c = new_r_Confirm(block, ptr, c, ir_relation_less_greater);
529 set_irn_n(succ, pos, c);
530 DB((dbg, LEVEL_2, "Replacing input %d of node %+F with %+F\n", pos, succ, c));
532 env->num_non_null += 1;
533 env->num_confirms += 1;
539 * Pre-walker: Called for every node to insert Confirm nodes
541 static void insert_Confirm(ir_node *node, void *data)
544 env_t *env = (env_t*) data;
546 switch (get_irn_opcode(node)) {
548 insert_Confirm_in_block(node, env);
551 ptr = get_Load_ptr(node);
552 if (! is_non_null_Confirm(ptr))
553 insert_non_null(ptr, get_nodes_block(node), env);
556 ptr = get_Store_ptr(node);
557 if (! is_non_null_Confirm(ptr))
558 insert_non_null(ptr, get_nodes_block(node), env);
566 * Construct Confirm nodes
568 void construct_confirms(ir_graph *irg)
571 int edges_active = edges_activated(irg);
573 FIRM_DBG_REGISTER(dbg, "firm.ana.confirm");
575 remove_critical_cf_edges(irg);
577 /* we need dominance info */
580 assert(get_irg_pinned(irg) == op_pin_state_pinned &&
581 "Nodes must be placed to insert Confirms");
583 if (! edges_active) {
588 env.num_confirms = 0;
591 env.num_non_null = 0;
593 if (get_opt_global_null_ptr_elimination()) {
594 /* do global NULL test elimination */
595 irg_walk_graph(irg, insert_Confirm, NULL, &env);
597 /* now, visit all blocks and add Confirms where possible */
598 irg_block_walk_graph(irg, insert_Confirm_in_block, NULL, &env);
601 DB((dbg, LEVEL_1, "# Confirms inserted : %u\n", env.num_confirms));
602 DB((dbg, LEVEL_1, "# Const replacements: %u\n", env.num_consts));
603 DB((dbg, LEVEL_1, "# node equalities : %u\n", env.num_eq));
604 DB((dbg, LEVEL_1, "# non-null Confirms : %u\n", env.num_non_null));
606 /* deactivate edges if they where off */
608 edges_deactivate(irg);
611 /* Construct a pass. */
612 ir_graph_pass_t *construct_confirms_pass(const char *name)
614 return def_graph_pass(name ? name : "confirm", construct_confirms);
617 static void remove_confirm(ir_node *n, void *env)
625 value = get_Confirm_value(n);
630 * Remove all Confirm nodes from a graph.
632 void remove_confirms(ir_graph *irg)
634 irg_walk_graph(irg, NULL, remove_confirm, NULL);
637 /* Construct a pass. */
638 ir_graph_pass_t *remove_confirms_pass(const char *name)
640 return def_graph_pass(name ? name : "rem_confirm", remove_confirms);