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
31 #include "irgraph_t.h"
35 #include "iropt_dbg.h"
36 #include "iredges_t.h"
48 typedef struct _env_t {
49 unsigned num_confirms; /**< Number of inserted Confirm nodes. */
50 unsigned num_consts; /**< Number of constants placed. */
51 unsigned num_eq; /**< Number of equalities placed. */
52 unsigned num_non_null; /**< Number of non-null Confirms. */
55 /** The debug handle. */
56 DEBUG_ONLY(static firm_dbg_module_t *dbg;)
59 * Return the effective use block of a node and it's predecessor on
62 * @param node the node
63 * @param pos the position of the used input
65 * This handles correctly Phi nodes.
67 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) {
88 const ir_edge_t *edge, *next;
94 for (edge = get_irn_out_edge_first(irn); edge; edge = next) {
95 ir_node *succ = get_edge_src_irn(edge);
96 int pos = get_edge_src_pos(edge);
97 ir_node *blk = get_effective_use_block(succ, pos);
99 next = get_irn_out_edge_next(irn, edge);
101 if (block_dominates(block, blk)) {
103 * Ok, we found a user of irn that is placed
104 * in a block dominated by the branch block.
105 * We can replace the input with the Constant
110 ir_mode *mode = get_irn_mode(irn);
111 ir_type *tp = get_irn_type(irn);
112 tarval *tv = new_tarval_from_long(nr, mode);
113 c = new_r_Const_type(current_ir_graph, block, mode, tv, tp);
116 set_irn_n(succ, pos, c);
117 DBG_OPT_CONFIRM_C(irn, c);
118 DB((dbg, LEVEL_2, "Replacing input %d of node %+F with %+F\n", pos, succ, c));
120 env->num_consts += 1;
126 * Handle a mode_b input of Cond nodes.
128 * @param block the block which is entered by the branch
129 * @param selector the mode_b node expressing the branch condition
130 * @param pnc the true/false condition branch
131 * @param env statistical environment
133 static void handle_modeb(ir_node *block, ir_node *selector, pn_Cond pnc, env_t *env) {
134 ir_node *cond, *old, *cond_block = NULL, *other_blk = NULL, *con = NULL;
135 ir_node *c_b = NULL, *c_o = NULL;
136 const ir_edge_t *edge, *next;
138 for (edge = get_irn_out_edge_first(selector); edge; edge = next) {
139 ir_node *user = get_edge_src_irn(edge);
140 int pos = get_edge_src_pos(edge);
141 ir_node *user_blk = get_effective_use_block(user, pos);
143 next = get_irn_out_edge_next(selector, edge);
144 if (block_dominates(block, user_blk)) {
146 * Ok, we found a usage of selector in a block
147 * dominated by the branch block.
148 * We can replace the input with true/false.
151 con = new_Const(mode_b, pnc == pn_Cond_true ? tarval_b_true : tarval_b_false);
153 old = get_irn_n(user, pos);
154 set_irn_n(user, pos, con);
155 DBG_OPT_CONFIRM_C(old, con);
157 DB((dbg, LEVEL_2, "Replacing input %d of node %+F with %+F\n", pos, user, con));
159 env->num_consts += 1;
163 /* get the other block */
164 if (other_blk == NULL) {
165 /* we have already tested, that block has only ONE Cond predecessor */
166 cond = get_Proj_pred(get_Block_cfgpred(block, 0));
167 cond_block = get_nodes_block(cond);
168 foreach_out_edge(cond, edge) {
169 ir_node *proj = get_edge_src_irn(edge);
170 if (get_Proj_proj(proj) == (long)pnc)
172 edge = get_irn_out_edge_first(proj);
173 other_blk = get_edge_src_irn(edge);
179 * Note the special case here: if block is a then, there might be no else
180 * block. In that case the other_block is the user_blk itself and pred_block
181 * is the cond_block ...
183 * Best would be to introduce a block here, removing this critical edge.
184 * For some reasons I cannot repair dominance here, so I have to remove
185 * ALL critical edges...
186 * FIXME: This should not be needed if we could repair dominance ...
190 n = get_Block_n_cfgpreds(user_blk);
193 * We have found a user in a non-dominated block:
194 * check, if all its block predecessors are dominated.
195 * If yes, place a Phi.
197 for (i = n - 1; i >= 0; --i) {
198 ir_node *pred_blk = get_Block_cfgpred_block(user_blk, i);
200 if (!block_dominates(block, pred_blk) &&
201 !block_dominates(other_blk, pred_blk)) {
202 /* can't do anything */
209 NEW_ARR_A(ir_node *, in, n);
210 /* ok, ALL predecessors are either dominated by block OR other block */
212 ir_node *c_true = new_Const(mode_b, tarval_b_true);
213 ir_node *c_false = new_Const(mode_b, tarval_b_false);
214 c_b = new_r_Confirm(current_ir_graph, cond_block, selector,
215 pnc == pn_Cond_true ? c_true : c_false, pn_Cmp_Eq);
216 c_o = new_r_Confirm(current_ir_graph, cond_block, selector,
217 pnc == pn_Cond_false ? c_true : c_false, pn_Cmp_Eq);
219 for (i = n - 1; i >= 0; --i) {
220 ir_node *pred_blk = get_Block_cfgpred_block(user_blk, i);
222 if (block_dominates(block, pred_blk))
227 phi = new_r_Phi(current_ir_graph, user_blk, n, in, mode_b);
228 set_irn_n(user, pos, phi);
235 * Handle an IF-branch.
237 * @param block the block which is entered by the branch
238 * @param cmp the Cmp node expressing the branch condition
239 * @param pnc the Compare relation for taking this branch
240 * @param env statistical environment
242 static void handle_if(ir_node *block, ir_node *cmp, pn_Cmp pnc, env_t *env) {
243 ir_node *left = get_Cmp_left(cmp);
244 ir_node *right = get_Cmp_right(cmp);
247 const ir_edge_t *edge, *next;
250 if (is_Bad(left) || is_Bad(right))
253 op = get_irn_op(left);
255 /* Do not create Confirm nodes for Cmp(Const, Const) constructs.
256 These are removed anyway */
257 if (op == op_Const && is_Const(right))
260 /* try to place the constant on the right side for a Confirm */
261 if (op == op_Const || op == op_SymConst) {
267 pnc = get_inversed_pnc(pnc);
271 * First case: both values are identical.
272 * replace the left one by the right (potentially const) one.
274 if (pnc == pn_Cmp_Eq) {
275 cond_block = get_Block_cfgpred_block(block, 0);
276 for (edge = get_irn_out_edge_first(left); edge; edge = next) {
277 ir_node *user = get_edge_src_irn(edge);
278 int pos = get_edge_src_pos(edge);
279 ir_node *blk = get_effective_use_block(user, pos);
281 next = get_irn_out_edge_next(left, edge);
282 if (block_dominates(block, blk)) {
284 * Ok, we found a usage of left in a block
285 * dominated by the branch block.
286 * We can replace the input with right.
288 set_irn_n(user, pos, right);
289 DBG_OPT_CONFIRM(left, right);
291 DB((dbg, LEVEL_2, "Replacing input %d of node %+F with %+F\n", pos, user, right));
294 } else if (block_dominates(blk, cond_block)) {
295 if (is_Const(right) && get_irn_pinned(user) == op_pin_state_floats) {
297 * left == Const and we found a movable user of left in a
298 * dominator of the Cond block
300 const ir_edge_t *edge, *next;
301 for (edge = get_irn_out_edge_first(user); edge; edge = next) {
302 ir_node *usr_of_usr = get_edge_src_irn(edge);
303 int npos = get_edge_src_pos(edge);
304 ir_node *blk = get_effective_use_block(usr_of_usr, npos);
306 next = get_irn_out_edge_next(user, edge);
307 if (block_dominates(block, blk)) {
309 * The user of the user is dominated by our true/false
310 * block. So, create a copy of user WITH the constant
311 * replacing it's pos'th input.
313 * This is always good for unop's and might be good
316 * If user has other user in the false/true block, code
317 * placement will move it down.
318 * If there are users in cond block or upper, we create
319 * "redundant ops", because one will have a const op,
320 * the other no const ...
322 ir_node *new_op = exact_copy(user);
323 set_nodes_block(new_op, block);
324 set_irn_n(new_op, pos, right);
325 set_irn_n(usr_of_usr, npos, new_op);
331 } else { /* not pn_Cmp_Eq cases */
334 for (edge = get_irn_out_edge_first(left); edge; edge = next) {
335 ir_node *succ = get_edge_src_irn(edge);
336 int pos = get_edge_src_pos(edge);
337 ir_node *blk = get_effective_use_block(succ, pos);
339 next = get_irn_out_edge_next(left, edge);
340 if (block_dominates(block, blk)) {
342 * Ok, we found a usage of left in a block
343 * dominated by the branch block.
344 * We can replace the input with a Confirm(left, pnc, right).
347 c = new_r_Confirm(current_ir_graph, block, left, right, pnc);
349 pos = get_edge_src_pos(edge);
350 set_irn_n(succ, pos, c);
351 DB((dbg, LEVEL_2, "Replacing input %d of node %+F with %+F\n", pos, succ, c));
353 env->num_confirms += 1;
360 * Pre-block-walker: Called for every block to insert Confirm nodes
362 static void insert_Confirm_in_block(ir_node *block, void *env) {
363 ir_node *cond, *proj, *selector;
367 * we can only handle blocks with only ONE control flow
370 if (get_Block_n_cfgpreds(block) != 1)
373 proj = get_Block_cfgpred(block, 0);
377 cond = get_Proj_pred(proj);
381 selector = get_Cond_selector(cond);
382 mode = get_irn_mode(selector);
384 if (mode == mode_b) {
388 handle_modeb(block, selector, get_Proj_proj(proj), env);
390 /* this should be an IF, check this */
391 if (! is_Proj(selector))
394 cmp = get_Proj_pred(selector);
398 pnc = get_Proj_proj(selector);
400 if (get_Proj_proj(proj) != pn_Cond_true) {
401 /* it's the false branch */
402 pnc = get_negated_pnc(pnc, mode);
404 DB((dbg, LEVEL_2, "At %+F using %+F Confirm %=\n", block, cmp, pnc));
406 handle_if(block, cmp, pnc, env);
407 } else if (mode_is_int(mode)) {
408 long proj_nr = get_Proj_proj(proj);
410 /* this is a CASE, but we cannot handle the default case */
411 if (proj_nr == get_Cond_defaultProj(cond))
414 handle_case(block, get_Cond_selector(cond), proj_nr, env);
416 } /* insert_Confirm_in_block */
419 * Checks if a node is a non-null Confirm.
421 static int is_non_null_Confirm(const ir_node *ptr) {
423 if (! is_Confirm(ptr))
425 if (get_Confirm_cmp(ptr) == pn_Cmp_Lg) {
426 ir_node *bound = get_Confirm_bound(ptr);
428 if (is_Const(bound) && is_Const_null(bound))
431 ptr = get_Confirm_value(ptr);
434 * While a SymConst is not a Confirm, it is non-null
435 * anyway. This helps to reduce the number of
436 * constructed Confirms.
438 if (is_SymConst_addr_ent(ptr))
441 } /* is_non_null_Confirm */
444 * The given pointer will be dereferenced, add non-null Confirms.
446 * @param ptr a node representing an address
447 * @param block the block of the dereferencing instruction
448 * @param env environment
450 static void insert_non_null(ir_node *ptr, ir_node *block, env_t *env) {
451 const ir_edge_t *edge, *next;
454 foreach_out_edge_safe(ptr, edge, next) {
455 ir_node *succ = get_edge_src_irn(edge);
460 /* for now, we place a Confirm only in front of a Cmp */
464 pos = get_edge_src_pos(edge);
465 blk = get_effective_use_block(succ, pos);
467 if (block_dominates(block, blk)) {
469 * Ok, we found a usage of ptr in a block
470 * dominated by the Load/Store block.
471 * We can replace the input with a Confirm(ptr, !=, NULL).
474 ir_mode *mode = get_irn_mode(ptr);
475 c = new_Const(mode, get_mode_null(mode));
477 c = new_r_Confirm(current_ir_graph, block, ptr, c, pn_Cmp_Lg);
480 set_irn_n(succ, pos, c);
481 DB((dbg, LEVEL_2, "Replacing input %d of node %+F with %+F\n", pos, succ, c));
483 env->num_non_null += 1;
484 env->num_confirms += 1;
487 } /* insert_non_null */
490 * Pre-walker: Called for every node to insert Confirm nodes
492 static void insert_Confirm(ir_node *node, void *env) {
495 switch (get_irn_opcode(node)) {
497 insert_Confirm_in_block(node, env);
500 ptr = get_Load_ptr(node);
501 if (! is_non_null_Confirm(ptr))
502 insert_non_null(ptr, get_nodes_block(node), env);
505 ptr = get_Store_ptr(node);
506 if (! is_non_null_Confirm(ptr))
507 insert_non_null(ptr, get_nodes_block(node), env);
512 } /* insert_Confirm */
515 * Construct Confirm nodes
517 void construct_confirms(ir_graph *irg) {
519 int edges_active = edges_activated(irg);
522 FIRM_DBG_REGISTER(dbg, "firm.ana.confirm");
524 remove_critical_cf_edges(irg);
526 /* we need dominance info */
529 assert(get_irg_pinned(irg) == op_pin_state_pinned &&
530 "Nodes must be placed to insert Confirms");
532 if (! edges_active) {
537 env.num_confirms = 0;
540 env.num_non_null = 0;
542 if (get_opt_global_null_ptr_elimination()) {
543 /* do global NULL test elimination */
544 irg_walk_graph(irg, insert_Confirm, NULL, &env);
546 /* now, visit all blocks and add Confirms where possible */
547 irg_block_walk_graph(irg, insert_Confirm_in_block, NULL, &env);
550 if (env.num_confirms | env.num_consts | env.num_eq) {
551 /* we have add nodes or changed DF edges */
552 set_irg_outs_inconsistent(irg);
554 /* the new nodes are not in the loop info */
555 set_irg_loopinfo_inconsistent(irg);
558 DB((dbg, LEVEL_1, "# Confirms inserted : %u\n", env.num_confirms));
559 DB((dbg, LEVEL_1, "# Const replacements: %u\n", env.num_consts));
560 DB((dbg, LEVEL_1, "# node equalities : %u\n", env.num_eq));
561 DB((dbg, LEVEL_1, "# non-null Confirms : %u\n", env.num_non_null));
563 /* deactivate edges if they where off */
565 edges_deactivate(irg);
566 } /* construct_confirms */
570 * Post-walker: Remove Confirm nodes
572 static void rem_Confirm(ir_node *n, void *env) {
575 ir_node *value = get_Confirm_value(n);
580 * Strange: a Confirm is its own bound. This can happen
581 * in dead blocks when Phi nodes are already removed.
583 exchange(n, new_Bad());
590 * Remove all Confirm nodes from a graph.
592 void remove_confirms(ir_graph *irg) {
593 int rem = get_opt_remove_confirm();
595 set_opt_remove_confirm(1);
596 optimize_graph_df(irg);
597 set_opt_remove_confirm(rem);
598 } /* remove_confirms */