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) {
68 /* the effective use of a Phi argument is in its predecessor block */
69 node = get_nodes_block(node);
70 return get_Block_cfgpred_block(node, pos);
72 return get_nodes_block(node);
76 * Handle a CASE-branch.
78 * @param block the block which is entered by the branch
79 * @param irn the node expressing the switch value
80 * @param nr the branch label
81 * @param env statistical environment
83 * Branch labels are a simple case. We can replace the value
84 * by a Const with the branch label.
86 static void handle_case(ir_node *block, ir_node *irn, long nr, env_t *env) {
87 const ir_edge_t *edge, *next;
93 for (edge = get_irn_out_edge_first(irn); edge; edge = next) {
94 ir_node *succ = get_edge_src_irn(edge);
95 int pos = get_edge_src_pos(edge);
96 ir_node *blk = get_effective_use_block(succ, pos);
98 next = get_irn_out_edge_next(irn, edge);
100 if (block_dominates(block, blk)) {
102 * Ok, we found a user of irn that is placed
103 * in a block dominated by the branch block.
104 * We can replace the input with the Constant
109 ir_mode *mode = get_irn_mode(irn);
110 ir_type *tp = get_irn_type(irn);
111 tarval *tv = new_tarval_from_long(nr, mode);
112 c = new_r_Const_type(current_ir_graph, tv, tp);
115 set_irn_n(succ, pos, c);
116 DBG_OPT_CONFIRM_C(irn, c);
117 DB((dbg, LEVEL_2, "Replacing input %d of node %+F with %+F\n", pos, succ, c));
119 env->num_consts += 1;
125 * Handle a mode_b input of Cond nodes.
127 * @param block the block which is entered by the branch
128 * @param selector the mode_b node expressing the branch condition
129 * @param pnc the true/false condition branch
130 * @param env statistical environment
132 static void handle_modeb(ir_node *block, ir_node *selector, pn_Cond pnc, env_t *env) {
133 ir_node *cond, *old, *cond_block = NULL, *other_blk = NULL, *con = NULL;
134 ir_node *c_b = NULL, *c_o = NULL;
135 const ir_edge_t *edge, *next;
137 for (edge = get_irn_out_edge_first(selector); edge; edge = next) {
138 ir_node *user = get_edge_src_irn(edge);
139 int pos = get_edge_src_pos(edge);
140 ir_node *user_blk = get_effective_use_block(user, pos);
142 next = get_irn_out_edge_next(selector, edge);
143 if (block_dominates(block, user_blk)) {
145 * Ok, we found a usage of selector in a block
146 * dominated by the branch block.
147 * We can replace the input with true/false.
150 con = new_Const(pnc == pn_Cond_true ? tarval_b_true : tarval_b_false);
152 old = get_irn_n(user, pos);
153 set_irn_n(user, pos, con);
154 DBG_OPT_CONFIRM_C(old, con);
156 DB((dbg, LEVEL_2, "Replacing input %d of node %+F with %+F\n", pos, user, con));
158 env->num_consts += 1;
162 /* get the other block */
163 if (other_blk == NULL) {
164 /* we have already tested, that block has only ONE Cond predecessor */
165 cond = get_Proj_pred(get_Block_cfgpred(block, 0));
166 cond_block = get_nodes_block(cond);
167 foreach_out_edge(cond, edge) {
168 ir_node *proj = get_edge_src_irn(edge);
169 if (get_Proj_proj(proj) == (long)pnc)
171 edge = get_irn_out_edge_first(proj);
172 other_blk = get_edge_src_irn(edge);
178 * Note the special case here: if block is a then, there might be no else
179 * block. In that case the other_block is the user_blk itself and pred_block
180 * is the cond_block ...
182 * Best would be to introduce a block here, removing this critical edge.
183 * For some reasons I cannot repair dominance here, so I have to remove
184 * ALL critical edges...
185 * FIXME: This should not be needed if we could repair dominance ...
189 n = get_Block_n_cfgpreds(user_blk);
192 * We have found a user in a non-dominated block:
193 * check, if all its block predecessors are dominated.
194 * If yes, place a Phi.
196 for (i = n - 1; i >= 0; --i) {
197 ir_node *pred_blk = get_Block_cfgpred_block(user_blk, i);
199 if (!block_dominates(block, pred_blk) &&
200 !block_dominates(other_blk, pred_blk)) {
201 /* can't do anything */
208 NEW_ARR_A(ir_node *, in, n);
209 /* ok, ALL predecessors are either dominated by block OR other block */
211 ir_node *c_true = new_Const(tarval_b_true);
212 ir_node *c_false = new_Const(tarval_b_false);
213 if (pnc == pn_Cond_true) {
221 for (i = n - 1; i >= 0; --i) {
222 ir_node *pred_blk = get_Block_cfgpred_block(user_blk, i);
224 if (block_dominates(block, pred_blk))
229 phi = new_r_Phi(user_blk, n, in, mode_b);
230 set_irn_n(user, pos, phi);
237 * Handle an IF-branch.
239 * @param block the block which is entered by the branch
240 * @param cmp the Cmp node expressing the branch condition
241 * @param pnc the Compare relation for taking this branch
242 * @param env statistical environment
244 static void handle_if(ir_node *block, ir_node *cmp, pn_Cmp pnc, env_t *env) {
245 ir_node *left = get_Cmp_left(cmp);
246 ir_node *right = get_Cmp_right(cmp);
249 const ir_edge_t *edge, *next;
252 if (is_Bad(left) || is_Bad(right))
255 op = get_irn_op(left);
257 /* Do not create Confirm nodes for Cmp(Const, Const) constructs.
258 These are removed anyway */
259 if (op == op_Const && is_Const(right))
262 /* try to place the constant on the right side for a Confirm */
263 if (op == op_Const || op == op_SymConst) {
269 pnc = get_inversed_pnc(pnc);
273 * First case: both values are identical.
274 * replace the left one by the right (potentially const) one.
276 if (pnc == pn_Cmp_Eq) {
277 cond_block = get_Block_cfgpred_block(block, 0);
278 for (edge = get_irn_out_edge_first(left); edge; edge = next) {
279 ir_node *user = get_edge_src_irn(edge);
280 int pos = get_edge_src_pos(edge);
281 ir_node *blk = get_effective_use_block(user, pos);
283 next = get_irn_out_edge_next(left, edge);
284 if (block_dominates(block, blk)) {
286 * Ok, we found a usage of left in a block
287 * dominated by the branch block.
288 * We can replace the input with right.
290 set_irn_n(user, pos, right);
291 DBG_OPT_CONFIRM(left, right);
293 DB((dbg, LEVEL_2, "Replacing input %d of node %+F with %+F\n", pos, user, right));
296 } else if (block_dominates(blk, cond_block)) {
297 if (is_Const(right) && get_irn_pinned(user) == op_pin_state_floats) {
299 * left == Const and we found a movable user of left in a
300 * dominator of the Cond block
302 const ir_edge_t *edge, *next;
303 for (edge = get_irn_out_edge_first(user); edge; edge = next) {
304 ir_node *usr_of_usr = get_edge_src_irn(edge);
305 int npos = get_edge_src_pos(edge);
306 ir_node *blk = get_effective_use_block(usr_of_usr, npos);
308 next = get_irn_out_edge_next(user, edge);
309 if (block_dominates(block, blk)) {
311 * The user of the user is dominated by our true/false
312 * block. So, create a copy of user WITH the constant
313 * replacing it's pos'th input.
315 * This is always good for unop's and might be good
318 * If user has other user in the false/true block, code
319 * placement will move it down.
320 * If there are users in cond block or upper, we create
321 * "redundant ops", because one will have a const op,
322 * the other no const ...
324 ir_node *new_op = exact_copy(user);
325 set_nodes_block(new_op, block);
326 set_irn_n(new_op, pos, right);
327 set_irn_n(usr_of_usr, npos, new_op);
333 } else { /* not pn_Cmp_Eq cases */
336 foreach_out_edge_safe(left, edge, next) {
337 ir_node *succ = get_edge_src_irn(edge);
338 int pos = get_edge_src_pos(edge);
339 ir_node *blk = get_effective_use_block(succ, pos);
341 if (block_dominates(block, blk)) {
343 * Ok, we found a usage of left in a block
344 * dominated by the branch block.
345 * We can replace the input with a Confirm(left, pnc, right).
348 c = new_r_Confirm(block, left, right, pnc);
350 pos = get_edge_src_pos(edge);
351 set_irn_n(succ, pos, c);
352 DB((dbg, LEVEL_2, "Replacing input %d of node %+F with %+F\n", pos, succ, c));
354 env->num_confirms += 1;
358 if (! is_Const(right)) {
359 /* also construct inverse Confirms */
362 pnc = get_inversed_pnc(pnc);
363 foreach_out_edge_safe(right, edge, next) {
364 ir_node *succ = get_edge_src_irn(edge);
371 pos = get_edge_src_pos(edge);
372 blk = get_effective_use_block(succ, pos);
374 if (block_dominates(block, blk)) {
376 * Ok, we found a usage of right in a block
377 * dominated by the branch block.
378 * We can replace the input with a Confirm(right, pnc^-1, left).
381 rc = new_r_Confirm(block, right, left, pnc);
383 pos = get_edge_src_pos(edge);
384 set_irn_n(succ, pos, rc);
385 DB((dbg, LEVEL_2, "Replacing input %d of node %+F with %+F\n", pos, succ, rc));
387 env->num_confirms += 1;
395 * Pre-block-walker: Called for every block to insert Confirm nodes
397 static void insert_Confirm_in_block(ir_node *block, void *env) {
398 ir_node *cond, *proj, *selector;
402 * we can only handle blocks with only ONE control flow
405 if (get_Block_n_cfgpreds(block) != 1)
408 proj = get_Block_cfgpred(block, 0);
412 cond = get_Proj_pred(proj);
416 selector = get_Cond_selector(cond);
417 mode = get_irn_mode(selector);
419 if (mode == mode_b) {
423 handle_modeb(block, selector, get_Proj_proj(proj), env);
425 /* this should be an IF, check this */
426 if (! is_Proj(selector))
429 cmp = get_Proj_pred(selector);
433 pnc = get_Proj_proj(selector);
435 if (get_Proj_proj(proj) != pn_Cond_true) {
436 /* it's the false branch */
437 mode = get_irn_mode(get_Cmp_left(cmp));
438 pnc = get_negated_pnc(pnc, mode);
440 DB((dbg, LEVEL_2, "At %+F using %+F Confirm %=\n", block, cmp, pnc));
442 handle_if(block, cmp, pnc, env);
443 } else if (mode_is_int(mode)) {
444 long proj_nr = get_Proj_proj(proj);
446 /* this is a CASE, but we cannot handle the default case */
447 if (proj_nr == get_Cond_default_proj(cond))
450 handle_case(block, get_Cond_selector(cond), proj_nr, env);
452 } /* insert_Confirm_in_block */
455 * Checks if a node is a non-null Confirm.
457 static int is_non_null_Confirm(const ir_node *ptr) {
459 if (! is_Confirm(ptr))
461 if (get_Confirm_cmp(ptr) == pn_Cmp_Lg) {
462 ir_node *bound = get_Confirm_bound(ptr);
464 if (is_Const(bound) && is_Const_null(bound))
467 ptr = get_Confirm_value(ptr);
470 * While a SymConst is not a Confirm, it is non-null
471 * anyway. This helps to reduce the number of
472 * constructed Confirms.
474 if (is_SymConst_addr_ent(ptr))
477 } /* is_non_null_Confirm */
480 * The given pointer will be dereferenced, add non-null Confirms.
482 * @param ptr a node representing an address
483 * @param block the block of the dereferencing instruction
484 * @param env environment
486 static void insert_non_null(ir_node *ptr, ir_node *block, env_t *env) {
487 const ir_edge_t *edge, *next;
490 foreach_out_edge_safe(ptr, edge, next) {
491 ir_node *succ = get_edge_src_irn(edge);
496 /* for now, we place a Confirm only in front of a Cmp */
500 pos = get_edge_src_pos(edge);
501 blk = get_effective_use_block(succ, pos);
503 if (block_dominates(block, blk)) {
505 * Ok, we found a usage of ptr in a block
506 * dominated by the Load/Store block.
507 * We can replace the input with a Confirm(ptr, !=, NULL).
510 ir_mode *mode = get_irn_mode(ptr);
511 c = new_Const(get_mode_null(mode));
513 c = new_r_Confirm(block, ptr, c, pn_Cmp_Lg);
516 set_irn_n(succ, pos, c);
517 DB((dbg, LEVEL_2, "Replacing input %d of node %+F with %+F\n", pos, succ, c));
519 env->num_non_null += 1;
520 env->num_confirms += 1;
523 } /* insert_non_null */
526 * Pre-walker: Called for every node to insert Confirm nodes
528 static void insert_Confirm(ir_node *node, void *env) {
531 switch (get_irn_opcode(node)) {
533 insert_Confirm_in_block(node, env);
536 ptr = get_Load_ptr(node);
537 if (! is_non_null_Confirm(ptr))
538 insert_non_null(ptr, get_nodes_block(node), env);
541 ptr = get_Store_ptr(node);
542 if (! is_non_null_Confirm(ptr))
543 insert_non_null(ptr, get_nodes_block(node), env);
548 } /* insert_Confirm */
551 * Construct Confirm nodes
553 void construct_confirms(ir_graph *irg) {
555 int edges_active = edges_activated(irg);
558 FIRM_DBG_REGISTER(dbg, "firm.ana.confirm");
560 remove_critical_cf_edges(irg);
562 /* we need dominance info */
565 assert(get_irg_pinned(irg) == op_pin_state_pinned &&
566 "Nodes must be placed to insert Confirms");
568 if (! edges_active) {
573 env.num_confirms = 0;
576 env.num_non_null = 0;
578 if (get_opt_global_null_ptr_elimination()) {
579 /* do global NULL test elimination */
580 irg_walk_graph(irg, insert_Confirm, NULL, &env);
582 /* now, visit all blocks and add Confirms where possible */
583 irg_block_walk_graph(irg, insert_Confirm_in_block, NULL, &env);
586 if (env.num_confirms | env.num_consts | env.num_eq) {
587 /* we have add nodes or changed DF edges */
588 set_irg_outs_inconsistent(irg);
590 /* the new nodes are not in the loop info */
591 set_irg_loopinfo_inconsistent(irg);
594 DB((dbg, LEVEL_1, "# Confirms inserted : %u\n", env.num_confirms));
595 DB((dbg, LEVEL_1, "# Const replacements: %u\n", env.num_consts));
596 DB((dbg, LEVEL_1, "# node equalities : %u\n", env.num_eq));
597 DB((dbg, LEVEL_1, "# non-null Confirms : %u\n", env.num_non_null));
599 /* deactivate edges if they where off */
601 edges_deactivate(irg);
602 } /* construct_confirms */
604 /* Construct a pass. */
605 ir_graph_pass_t *construct_confirms_pass(const char *name) {
606 return def_graph_pass(name ? name : "confirm", construct_confirms);
607 } /* construct_confirms_pass */
611 * Post-walker: Remove Confirm nodes
613 static void rem_Confirm(ir_node *n, void *env) {
616 ir_node *value = get_Confirm_value(n);
621 * Strange: a Confirm is its own bound. This can happen
622 * in dead blocks when Phi nodes are already removed.
624 exchange(n, new_Bad());
631 * Remove all Confirm nodes from a graph.
633 void remove_confirms(ir_graph *irg) {
634 int rem = get_opt_remove_confirm();
636 set_opt_remove_confirm(1);
637 optimize_graph_df(irg);
638 set_opt_remove_confirm(rem);
639 } /* remove_confirms */
641 /* Construct a pass. */
642 ir_graph_pass_t *remove_confirms_pass(const char *name) {
643 return def_graph_pass(name ? name : "rem_confirm", remove_confirms);
644 } /* remove_confirms_pass */