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 "irgraph_t.h"
33 #include "iropt_dbg.h"
34 #include "iredges_t.h"
47 typedef struct _env_t {
48 unsigned num_confirms; /**< Number of inserted Confirm nodes. */
49 unsigned num_consts; /**< Number of constants placed. */
50 unsigned num_eq; /**< Number of equalities placed. */
51 unsigned num_non_null; /**< Number of non-null Confirms. */
54 /** The debug handle. */
55 DEBUG_ONLY(static firm_dbg_module_t *dbg;)
58 * Return the effective use block of a node and it's predecessor on
61 * @param node the node
62 * @param pos the position of the used input
64 * This handles correctly Phi nodes.
66 static ir_node *get_effective_use_block(ir_node *node, int pos)
69 /* the effective use of a Phi argument is in its predecessor block */
70 node = get_nodes_block(node);
71 return get_Block_cfgpred_block(node, pos);
73 return get_nodes_block(node);
77 * Handle a CASE-branch.
79 * @param block the block which is entered by the branch
80 * @param irn the node expressing the switch value
81 * @param nr the branch label
82 * @param env statistical environment
84 * Branch labels are a simple case. We can replace the value
85 * by a Const with the branch label.
87 static void handle_case(ir_node *block, ir_node *irn, long nr, env_t *env)
89 const ir_edge_t *edge, *next;
95 for (edge = get_irn_out_edge_first(irn); edge; edge = next) {
96 ir_node *succ = get_edge_src_irn(edge);
97 int pos = get_edge_src_pos(edge);
98 ir_node *blk = get_effective_use_block(succ, pos);
100 next = get_irn_out_edge_next(irn, edge);
102 if (block_dominates(block, blk)) {
104 * Ok, we found a user of irn that is placed
105 * in a block dominated by the branch block.
106 * We can replace the input with the Constant
111 ir_mode *mode = get_irn_mode(irn);
112 ir_type *tp = get_irn_type(irn);
113 tarval *tv = new_tarval_from_long(nr, mode);
114 c = new_r_Const_type(current_ir_graph, tv, tp);
117 set_irn_n(succ, pos, c);
118 DBG_OPT_CONFIRM_C(irn, c);
119 DB((dbg, LEVEL_2, "Replacing input %d of node %+F with %+F\n", pos, succ, c));
121 env->num_consts += 1;
127 * Handle a mode_b input of Cond nodes.
129 * @param block the block which is entered by the branch
130 * @param selector the mode_b node expressing the branch condition
131 * @param pnc the true/false condition branch
132 * @param env statistical environment
134 static void handle_modeb(ir_node *block, ir_node *selector, pn_Cond pnc, env_t *env)
136 ir_node *cond, *old, *cond_block = NULL, *other_blk = NULL, *con = NULL;
137 ir_node *c_b = NULL, *c_o = NULL;
138 const ir_edge_t *edge, *next;
140 for (edge = get_irn_out_edge_first(selector); edge; edge = next) {
141 ir_node *user = get_edge_src_irn(edge);
142 int pos = get_edge_src_pos(edge);
143 ir_node *user_blk = get_effective_use_block(user, pos);
145 next = get_irn_out_edge_next(selector, edge);
146 if (block_dominates(block, user_blk)) {
148 * Ok, we found a usage of selector in a block
149 * dominated by the branch block.
150 * We can replace the input with true/false.
153 con = new_Const(pnc == pn_Cond_true ? tarval_b_true : tarval_b_false);
155 old = get_irn_n(user, pos);
156 set_irn_n(user, pos, con);
157 DBG_OPT_CONFIRM_C(old, con);
159 DB((dbg, LEVEL_2, "Replacing input %d of node %+F with %+F\n", pos, user, con));
161 env->num_consts += 1;
165 /* get the other block */
166 if (other_blk == NULL) {
167 /* we have already tested, that block has only ONE Cond predecessor */
168 cond = get_Proj_pred(get_Block_cfgpred(block, 0));
169 cond_block = get_nodes_block(cond);
170 foreach_out_edge(cond, edge) {
171 ir_node *proj = get_edge_src_irn(edge);
172 if (get_Proj_proj(proj) == (long)pnc)
174 edge = get_irn_out_edge_first(proj);
175 other_blk = get_edge_src_irn(edge);
181 * Note the special case here: if block is a then, there might be no else
182 * block. In that case the other_block is the user_blk itself and pred_block
183 * is the cond_block ...
185 * Best would be to introduce a block here, removing this critical edge.
186 * For some reasons I cannot repair dominance here, so I have to remove
187 * ALL critical edges...
188 * FIXME: This should not be needed if we could repair dominance ...
192 n = get_Block_n_cfgpreds(user_blk);
195 * We have found a user in a non-dominated block:
196 * check, if all its block predecessors are dominated.
197 * If yes, place a Phi.
199 for (i = n - 1; i >= 0; --i) {
200 ir_node *pred_blk = get_Block_cfgpred_block(user_blk, i);
202 if (!block_dominates(block, pred_blk) &&
203 !block_dominates(other_blk, pred_blk)) {
204 /* can't do anything */
211 NEW_ARR_A(ir_node *, in, n);
212 /* ok, ALL predecessors are either dominated by block OR other block */
214 ir_node *c_true = new_Const(tarval_b_true);
215 ir_node *c_false = new_Const(tarval_b_false);
216 if (pnc == pn_Cond_true) {
224 for (i = n - 1; i >= 0; --i) {
225 ir_node *pred_blk = get_Block_cfgpred_block(user_blk, i);
227 if (block_dominates(block, pred_blk))
232 phi = new_r_Phi(user_blk, n, in, mode_b);
233 set_irn_n(user, pos, phi);
240 * Handle an IF-branch.
242 * @param block the block which is entered by the branch
243 * @param cmp the Cmp node expressing the branch condition
244 * @param pnc the Compare relation for taking this branch
245 * @param env statistical environment
247 static void handle_if(ir_node *block, ir_node *cmp, pn_Cmp pnc, env_t *env)
249 ir_node *left = get_Cmp_left(cmp);
250 ir_node *right = get_Cmp_right(cmp);
253 const ir_edge_t *edge, *next;
256 if (is_Bad(left) || is_Bad(right))
259 op = get_irn_op(left);
261 /* Do not create Confirm nodes for Cmp(Const, Const) constructs.
262 These are removed anyway */
263 if (op == op_Const && is_Const(right))
266 /* try to place the constant on the right side for a Confirm */
267 if (op == op_Const || op == op_SymConst) {
273 pnc = get_inversed_pnc(pnc);
277 * First case: both values are identical.
278 * replace the left one by the right (potentially const) one.
280 if (pnc == pn_Cmp_Eq) {
281 cond_block = get_Block_cfgpred_block(block, 0);
282 for (edge = get_irn_out_edge_first(left); edge; edge = next) {
283 ir_node *user = get_edge_src_irn(edge);
284 int pos = get_edge_src_pos(edge);
285 ir_node *blk = get_effective_use_block(user, pos);
287 next = get_irn_out_edge_next(left, edge);
288 if (block_dominates(block, blk)) {
290 * Ok, we found a usage of left in a block
291 * dominated by the branch block.
292 * We can replace the input with right.
294 set_irn_n(user, pos, right);
295 DBG_OPT_CONFIRM(left, right);
297 DB((dbg, LEVEL_2, "Replacing input %d of node %+F with %+F\n", pos, user, right));
300 } else if (block_dominates(blk, cond_block)) {
301 if (is_Const(right) && get_irn_pinned(user) == op_pin_state_floats) {
303 * left == Const and we found a movable user of left in a
304 * dominator of the Cond block
306 const ir_edge_t *edge, *next;
307 for (edge = get_irn_out_edge_first(user); edge; edge = next) {
308 ir_node *usr_of_usr = get_edge_src_irn(edge);
309 int npos = get_edge_src_pos(edge);
310 ir_node *blk = get_effective_use_block(usr_of_usr, npos);
312 next = get_irn_out_edge_next(user, edge);
313 if (block_dominates(block, blk)) {
315 * The user of the user is dominated by our true/false
316 * block. So, create a copy of user WITH the constant
317 * replacing it's pos'th input.
319 * This is always good for unop's and might be good
322 * If user has other user in the false/true block, code
323 * placement will move it down.
324 * If there are users in cond block or upper, we create
325 * "redundant ops", because one will have a const op,
326 * the other no const ...
328 ir_node *new_op = exact_copy(user);
329 set_nodes_block(new_op, block);
330 set_irn_n(new_op, pos, right);
331 set_irn_n(usr_of_usr, npos, new_op);
337 } else { /* not pn_Cmp_Eq cases */
340 foreach_out_edge_safe(left, edge, next) {
341 ir_node *succ = get_edge_src_irn(edge);
342 int pos = get_edge_src_pos(edge);
343 ir_node *blk = get_effective_use_block(succ, pos);
345 if (block_dominates(block, blk)) {
347 * Ok, we found a usage of left in a block
348 * dominated by the branch block.
349 * We can replace the input with a Confirm(left, pnc, right).
352 c = new_r_Confirm(block, left, right, pnc);
354 pos = get_edge_src_pos(edge);
355 set_irn_n(succ, pos, c);
356 DB((dbg, LEVEL_2, "Replacing input %d of node %+F with %+F\n", pos, succ, c));
358 env->num_confirms += 1;
362 if (! is_Const(right)) {
363 /* also construct inverse Confirms */
366 pnc = get_inversed_pnc(pnc);
367 foreach_out_edge_safe(right, edge, next) {
368 ir_node *succ = get_edge_src_irn(edge);
375 pos = get_edge_src_pos(edge);
376 blk = get_effective_use_block(succ, pos);
378 if (block_dominates(block, blk)) {
380 * Ok, we found a usage of right in a block
381 * dominated by the branch block.
382 * We can replace the input with a Confirm(right, pnc^-1, left).
385 rc = new_r_Confirm(block, right, left, pnc);
387 pos = get_edge_src_pos(edge);
388 set_irn_n(succ, pos, rc);
389 DB((dbg, LEVEL_2, "Replacing input %d of node %+F with %+F\n", pos, succ, rc));
391 env->num_confirms += 1;
399 * Pre-block-walker: Called for every block to insert Confirm nodes
401 static void insert_Confirm_in_block(ir_node *block, void *env)
403 ir_node *cond, *proj, *selector;
407 * we can only handle blocks with only ONE control flow
410 if (get_Block_n_cfgpreds(block) != 1)
413 proj = get_Block_cfgpred(block, 0);
417 cond = get_Proj_pred(proj);
421 selector = get_Cond_selector(cond);
422 mode = get_irn_mode(selector);
424 if (mode == mode_b) {
428 handle_modeb(block, selector, get_Proj_proj(proj), env);
430 /* this should be an IF, check this */
431 if (! is_Proj(selector))
434 cmp = get_Proj_pred(selector);
438 pnc = get_Proj_proj(selector);
440 if (get_Proj_proj(proj) != pn_Cond_true) {
441 /* it's the false branch */
442 mode = get_irn_mode(get_Cmp_left(cmp));
443 pnc = get_negated_pnc(pnc, mode);
445 DB((dbg, LEVEL_2, "At %+F using %+F Confirm %=\n", block, cmp, pnc));
447 handle_if(block, cmp, pnc, 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_cmp(ptr) == pn_Cmp_Lg) {
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 c = new_Const(get_mode_null(mode));
520 c = new_r_Confirm(block, ptr, c, pn_Cmp_Lg);
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 *env)
539 switch (get_irn_opcode(node)) {
541 insert_Confirm_in_block(node, env);
544 ptr = get_Load_ptr(node);
545 if (! is_non_null_Confirm(ptr))
546 insert_non_null(ptr, get_nodes_block(node), env);
549 ptr = get_Store_ptr(node);
550 if (! is_non_null_Confirm(ptr))
551 insert_non_null(ptr, get_nodes_block(node), env);
556 } /* insert_Confirm */
559 * Construct Confirm nodes
561 void construct_confirms(ir_graph *irg)
564 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 if (env.num_confirms | env.num_consts | env.num_eq) {
596 /* we have add nodes or changed DF edges */
597 set_irg_outs_inconsistent(irg);
599 /* the new nodes are not in the loop info */
600 set_irg_loopinfo_inconsistent(irg);
603 DB((dbg, LEVEL_1, "# Confirms inserted : %u\n", env.num_confirms));
604 DB((dbg, LEVEL_1, "# Const replacements: %u\n", env.num_consts));
605 DB((dbg, LEVEL_1, "# node equalities : %u\n", env.num_eq));
606 DB((dbg, LEVEL_1, "# non-null Confirms : %u\n", env.num_non_null));
608 /* deactivate edges if they where off */
610 edges_deactivate(irg);
611 } /* construct_confirms */
613 /* Construct a pass. */
614 ir_graph_pass_t *construct_confirms_pass(const char *name)
616 return def_graph_pass(name ? name : "confirm", construct_confirms);
617 } /* construct_confirms_pass */
621 * Post-walker: Remove Confirm nodes
623 static void rem_Confirm(ir_node *n, void *env)
627 ir_node *value = get_Confirm_value(n);
632 * Strange: a Confirm is its own bound. This can happen
633 * in dead blocks when Phi nodes are already removed.
635 exchange(n, new_Bad());
642 * Remove all Confirm nodes from a graph.
644 void remove_confirms(ir_graph *irg)
646 int rem = get_opt_remove_confirm();
648 set_opt_remove_confirm(1);
649 optimize_graph_df(irg);
650 set_opt_remove_confirm(rem);
651 } /* remove_confirms */
653 /* Construct a pass. */
654 ir_graph_pass_t *remove_confirms_pass(const char *name)
656 return def_graph_pass(name ? name : "rem_confirm", remove_confirms);
657 } /* remove_confirms_pass */