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
29 #include "irconsconfirm.h"
31 #include "irgraph_t.h"
35 #include "iropt_dbg.h"
36 #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);
79 * Handle a CASE-branch.
81 * @param block the block which is entered by the branch
82 * @param irn the node expressing the switch value
83 * @param nr the branch label
84 * @param env statistical environment
86 * Branch labels are a simple case. We can replace the value
87 * by a Const with the branch label.
89 static void handle_case(ir_node *block, ir_node *irn, long nr, env_t *env)
91 const ir_edge_t *edge, *next;
97 for (edge = get_irn_out_edge_first(irn); edge; edge = next) {
98 ir_node *succ = get_edge_src_irn(edge);
99 int pos = get_edge_src_pos(edge);
100 ir_node *blk = get_effective_use_block(succ, pos);
102 next = get_irn_out_edge_next(irn, edge);
104 if (block_dominates(block, blk)) {
106 * Ok, we found a user of irn that is placed
107 * in a block dominated by the branch block.
108 * We can replace the input with the Constant
113 ir_mode *mode = get_irn_mode(irn);
114 ir_tarval *tv = new_tarval_from_long(nr, mode);
115 c = new_r_Const(current_ir_graph, tv);
118 set_irn_n(succ, pos, c);
119 DBG_OPT_CONFIRM_C(irn, c);
120 DB((dbg, LEVEL_2, "Replacing input %d of node %+F with %+F\n", pos, succ, c));
122 env->num_consts += 1;
128 * Handle a mode_b input of Cond nodes.
130 * @param block the block which is entered by the branch
131 * @param selector the mode_b node expressing the branch condition
132 * @param pnc the true/false condition branch
133 * @param env statistical environment
135 static void handle_modeb(ir_node *block, ir_node *selector, pn_Cond pnc, env_t *env)
137 ir_node *cond, *old, *other_blk = NULL, *con = NULL;
138 ir_node *c_b = NULL, *c_o = NULL;
139 const ir_edge_t *edge, *next;
141 for (edge = get_irn_out_edge_first(selector); edge; edge = next) {
142 ir_node *user = get_edge_src_irn(edge);
143 int pos = get_edge_src_pos(edge);
144 ir_node *user_blk = get_effective_use_block(user, pos);
146 next = get_irn_out_edge_next(selector, edge);
147 if (block_dominates(block, user_blk)) {
149 * Ok, we found a usage of selector in a block
150 * dominated by the branch block.
151 * We can replace the input with true/false.
154 ir_graph *irg = get_irn_irg(block);
155 con = new_r_Const(irg, pnc == pn_Cond_true ? tarval_b_true : tarval_b_false);
157 old = get_irn_n(user, pos);
158 set_irn_n(user, pos, con);
159 DBG_OPT_CONFIRM_C(old, con);
161 DB((dbg, LEVEL_2, "Replacing input %d of node %+F with %+F\n", pos, user, con));
163 env->num_consts += 1;
167 /* get the other block */
168 if (other_blk == NULL) {
169 /* we have already tested, that block has only ONE Cond predecessor */
170 cond = get_Proj_pred(get_Block_cfgpred(block, 0));
171 foreach_out_edge(cond, edge) {
172 ir_node *proj = get_edge_src_irn(edge);
173 if (get_Proj_proj(proj) == (long)pnc)
175 edge = get_irn_out_edge_first(proj);
176 other_blk = get_edge_src_irn(edge);
182 * Note the special case here: if block is a then, there might be no else
183 * block. In that case the other_block is the user_blk itself and pred_block
184 * is the cond_block ...
186 * Best would be to introduce a block here, removing this critical edge.
187 * For some reasons I cannot repair dominance here, so I have to remove
188 * ALL critical edges...
189 * FIXME: This should not be needed if we could repair dominance ...
193 n = get_Block_n_cfgpreds(user_blk);
196 * We have found a user in a non-dominated block:
197 * check, if all its block predecessors are dominated.
198 * If yes, place a Phi.
200 for (i = n - 1; i >= 0; --i) {
201 ir_node *pred_blk = get_Block_cfgpred_block(user_blk, i);
203 if (!block_dominates(block, pred_blk) &&
204 !block_dominates(other_blk, pred_blk)) {
205 /* can't do anything */
212 NEW_ARR_A(ir_node *, in, n);
213 /* ok, ALL predecessors are either dominated by block OR other block */
215 ir_graph *irg = get_irn_irg(block);
216 ir_node *c_true = new_r_Const(irg, tarval_b_true);
217 ir_node *c_false = new_r_Const(irg, tarval_b_false);
218 env->num_consts += 2;
219 if (pnc == pn_Cond_true) {
227 for (i = n - 1; i >= 0; --i) {
228 ir_node *pred_blk = get_Block_cfgpred_block(user_blk, i);
230 if (block_dominates(block, pred_blk))
235 phi = new_r_Phi(user_blk, n, in, mode_b);
236 set_irn_n(user, pos, phi);
244 * Handle an IF-branch.
246 * @param block the block which is entered by the branch
247 * @param cmp the Cmp node expressing the branch condition
248 * @param rel the Compare relation for taking this branch
249 * @param env statistical environment
251 static void handle_if(ir_node *block, ir_node *cmp, ir_relation rel, env_t *env)
253 ir_node *left = get_Cmp_left(cmp);
254 ir_node *right = get_Cmp_right(cmp);
257 const ir_edge_t *edge, *next;
260 if (is_Bad(left) || is_Bad(right))
263 op = get_irn_op(left);
265 /* Do not create Confirm nodes for Cmp(Const, Const) constructs.
266 These are removed anyway */
267 if (op == op_Const && is_Const(right))
270 /* try to place the constant on the right side for a Confirm */
271 if (op == op_Const || op == op_SymConst) {
277 rel = get_inversed_relation(rel);
281 * First case: both values are identical.
282 * replace the left one by the right (potentially const) one.
284 if (rel == ir_relation_equal) {
285 cond_block = get_Block_cfgpred_block(block, 0);
286 for (edge = get_irn_out_edge_first(left); edge; edge = next) {
287 ir_node *user = get_edge_src_irn(edge);
288 int pos = get_edge_src_pos(edge);
289 ir_node *blk = get_effective_use_block(user, pos);
291 next = get_irn_out_edge_next(left, edge);
292 if (block_dominates(block, blk)) {
294 * Ok, we found a usage of left in a block
295 * dominated by the branch block.
296 * We can replace the input with right.
298 set_irn_n(user, pos, right);
299 DBG_OPT_CONFIRM(left, right);
301 DB((dbg, LEVEL_2, "Replacing input %d of node %+F with %+F\n", pos, user, right));
304 } else if (block_dominates(blk, cond_block)
306 && get_irn_pinned(user) == op_pin_state_floats) {
308 * left == Const and we found a movable user of left in a
309 * dominator of the Cond block
311 const ir_edge_t *edge, *next;
312 for (edge = get_irn_out_edge_first(user); edge; edge = next) {
313 ir_node *usr_of_usr = get_edge_src_irn(edge);
314 int npos = get_edge_src_pos(edge);
315 ir_node *blk = get_effective_use_block(usr_of_usr, npos);
317 next = get_irn_out_edge_next(user, edge);
318 if (block_dominates(block, blk)) {
320 * The user of the user is dominated by our true/false
321 * block. So, create a copy of user WITH the constant
322 * replacing its pos'th input.
324 * This is always good for unop's and might be good
327 * If user has other user in the false/true block, code
328 * placement will move it down.
329 * If there are users in cond block or upper, we create
330 * "redundant ops", because one will have a const op,
331 * the other no const ...
333 ir_node *new_op = exact_copy(user);
334 set_nodes_block(new_op, block);
335 set_irn_n(new_op, pos, right);
336 set_irn_n(usr_of_usr, npos, new_op);
342 } else { /* not ir_relation_equal cases */
345 foreach_out_edge_safe(left, edge, next) {
346 ir_node *succ = get_edge_src_irn(edge);
347 int pos = get_edge_src_pos(edge);
348 ir_node *blk = get_effective_use_block(succ, pos);
350 if (block_dominates(block, blk)) {
352 * Ok, we found a usage of left in a block
353 * dominated by the branch block.
354 * We can replace the input with a Confirm(left, pnc, right).
357 c = new_r_Confirm(block, left, right, rel);
359 pos = get_edge_src_pos(edge);
360 set_irn_n(succ, pos, c);
361 DB((dbg, LEVEL_2, "Replacing input %d of node %+F with %+F\n", pos, succ, c));
363 env->num_confirms += 1;
367 if (! is_Const(right)) {
368 /* also construct inverse Confirms */
371 rel = get_inversed_relation(rel);
372 foreach_out_edge_safe(right, edge, next) {
373 ir_node *succ = get_edge_src_irn(edge);
380 pos = get_edge_src_pos(edge);
381 blk = get_effective_use_block(succ, pos);
383 if (block_dominates(block, blk)) {
385 * Ok, we found a usage of right in a block
386 * dominated by the branch block.
387 * We can replace the input with a Confirm(right, rel^-1, left).
390 rc = new_r_Confirm(block, right, left, rel);
392 pos = get_edge_src_pos(edge);
393 set_irn_n(succ, pos, rc);
394 DB((dbg, LEVEL_2, "Replacing input %d of node %+F with %+F\n", pos, succ, rc));
396 env->num_confirms += 1;
404 * Pre-block-walker: Called for every block to insert Confirm nodes
406 static void insert_Confirm_in_block(ir_node *block, void *data)
408 ir_node *cond, *proj, *selector;
410 env_t *env = (env_t*) data;
413 * we can only handle blocks with only ONE control flow
416 if (get_Block_n_cfgpreds(block) != 1)
419 proj = get_Block_cfgpred(block, 0);
423 cond = get_Proj_pred(proj);
427 selector = get_Cond_selector(cond);
428 mode = get_irn_mode(selector);
430 if (mode == mode_b) {
433 handle_modeb(block, selector, (pn_Cond) get_Proj_proj(proj), env);
435 if (! is_Cmp(selector))
438 rel = get_Cmp_relation(selector);
440 if (get_Proj_proj(proj) != pn_Cond_true) {
441 /* it's the false branch */
442 mode = get_irn_mode(get_Cmp_left(selector));
443 rel = get_negated_relation(rel);
445 DB((dbg, LEVEL_2, "At %+F using %+F Confirm %=\n", block, selector, rel));
447 handle_if(block, selector, rel, env);
448 } else if (mode_is_int(mode)) {
449 long proj_nr = get_Proj_proj(proj);
451 /* this is a CASE, but we cannot handle the default case */
452 if (proj_nr == get_Cond_default_proj(cond))
455 handle_case(block, get_Cond_selector(cond), proj_nr, env);
457 } /* insert_Confirm_in_block */
460 * Checks if a node is a non-null Confirm.
462 static int is_non_null_Confirm(const ir_node *ptr)
465 if (! is_Confirm(ptr))
467 if (get_Confirm_relation(ptr) == ir_relation_less_greater) {
468 ir_node *bound = get_Confirm_bound(ptr);
470 if (is_Const(bound) && is_Const_null(bound))
473 ptr = get_Confirm_value(ptr);
476 * While a SymConst is not a Confirm, it is non-null
477 * anyway. This helps to reduce the number of
478 * constructed Confirms.
480 if (is_SymConst_addr_ent(ptr))
483 } /* is_non_null_Confirm */
486 * The given pointer will be dereferenced, add non-null Confirms.
488 * @param ptr a node representing an address
489 * @param block the block of the dereferencing instruction
490 * @param env environment
492 static void insert_non_null(ir_node *ptr, ir_node *block, env_t *env)
494 const ir_edge_t *edge, *next;
497 foreach_out_edge_safe(ptr, edge, next) {
498 ir_node *succ = get_edge_src_irn(edge);
503 /* for now, we place a Confirm only in front of a Cmp */
507 pos = get_edge_src_pos(edge);
508 blk = get_effective_use_block(succ, pos);
510 if (block_dominates(block, blk)) {
512 * Ok, we found a usage of ptr in a block
513 * dominated by the Load/Store block.
514 * We can replace the input with a Confirm(ptr, !=, NULL).
517 ir_mode *mode = get_irn_mode(ptr);
518 ir_graph *irg = get_irn_irg(block);
519 c = new_r_Const(irg, get_mode_null(mode));
520 c = new_r_Confirm(block, ptr, c, ir_relation_less_greater);
523 set_irn_n(succ, pos, c);
524 DB((dbg, LEVEL_2, "Replacing input %d of node %+F with %+F\n", pos, succ, c));
526 env->num_non_null += 1;
527 env->num_confirms += 1;
530 } /* insert_non_null */
533 * Pre-walker: Called for every node to insert Confirm nodes
535 static void insert_Confirm(ir_node *node, void *data)
538 env_t *env = (env_t*) data;
540 switch (get_irn_opcode(node)) {
542 insert_Confirm_in_block(node, env);
545 ptr = get_Load_ptr(node);
546 if (! is_non_null_Confirm(ptr))
547 insert_non_null(ptr, get_nodes_block(node), env);
550 ptr = get_Store_ptr(node);
551 if (! is_non_null_Confirm(ptr))
552 insert_non_null(ptr, get_nodes_block(node), env);
557 } /* insert_Confirm */
560 * Construct Confirm nodes
562 void construct_confirms(ir_graph *irg)
565 int edges_active = edges_activated(irg);
567 FIRM_DBG_REGISTER(dbg, "firm.ana.confirm");
569 remove_critical_cf_edges(irg);
571 /* we need dominance info */
574 assert(get_irg_pinned(irg) == op_pin_state_pinned &&
575 "Nodes must be placed to insert Confirms");
577 if (! edges_active) {
582 env.num_confirms = 0;
585 env.num_non_null = 0;
587 if (get_opt_global_null_ptr_elimination()) {
588 /* do global NULL test elimination */
589 irg_walk_graph(irg, insert_Confirm, NULL, &env);
591 /* now, visit all blocks and add Confirms where possible */
592 irg_block_walk_graph(irg, insert_Confirm_in_block, NULL, &env);
595 DB((dbg, LEVEL_1, "# Confirms inserted : %u\n", env.num_confirms));
596 DB((dbg, LEVEL_1, "# Const replacements: %u\n", env.num_consts));
597 DB((dbg, LEVEL_1, "# node equalities : %u\n", env.num_eq));
598 DB((dbg, LEVEL_1, "# non-null Confirms : %u\n", env.num_non_null));
600 /* deactivate edges if they where off */
602 edges_deactivate(irg);
603 } /* construct_confirms */
605 /* Construct a pass. */
606 ir_graph_pass_t *construct_confirms_pass(const char *name)
608 return def_graph_pass(name ? name : "confirm", construct_confirms);
609 } /* construct_confirms_pass */
611 static void remove_confirm(ir_node *n, void *env)
619 value = get_Confirm_value(n);
624 * Remove all Confirm nodes from a graph.
626 void remove_confirms(ir_graph *irg)
628 irg_walk_graph(irg, NULL, remove_confirm, NULL);
629 } /* remove_confirms */
631 /* Construct a pass. */
632 ir_graph_pass_t *remove_confirms_pass(const char *name)
634 return def_graph_pass(name ? name : "rem_confirm", remove_confirms);
635 } /* remove_confirms_pass */