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 it's 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_type *tp = get_irn_type(irn);
115 tarval *tv = new_tarval_from_long(nr, mode);
116 c = new_r_Const_type(current_ir_graph, tv, tp);
119 set_irn_n(succ, pos, c);
120 DBG_OPT_CONFIRM_C(irn, c);
121 DB((dbg, LEVEL_2, "Replacing input %d of node %+F with %+F\n", pos, succ, c));
123 env->num_consts += 1;
129 * Handle a mode_b input of Cond nodes.
131 * @param block the block which is entered by the branch
132 * @param selector the mode_b node expressing the branch condition
133 * @param pnc the true/false condition branch
134 * @param env statistical environment
136 static void handle_modeb(ir_node *block, ir_node *selector, pn_Cond pnc, env_t *env)
138 ir_node *cond, *old, *other_blk = NULL, *con = NULL;
139 ir_node *c_b = NULL, *c_o = NULL;
140 const ir_edge_t *edge, *next;
142 for (edge = get_irn_out_edge_first(selector); edge; edge = next) {
143 ir_node *user = get_edge_src_irn(edge);
144 int pos = get_edge_src_pos(edge);
145 ir_node *user_blk = get_effective_use_block(user, pos);
147 next = get_irn_out_edge_next(selector, edge);
148 if (block_dominates(block, user_blk)) {
150 * Ok, we found a usage of selector in a block
151 * dominated by the branch block.
152 * We can replace the input with true/false.
155 con = new_Const(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_node *c_true = new_Const(tarval_b_true);
216 ir_node *c_false = new_Const(tarval_b_false);
217 if (pnc == pn_Cond_true) {
225 for (i = n - 1; i >= 0; --i) {
226 ir_node *pred_blk = get_Block_cfgpred_block(user_blk, i);
228 if (block_dominates(block, pred_blk))
233 phi = new_r_Phi(user_blk, n, in, mode_b);
234 set_irn_n(user, pos, phi);
241 * Handle an IF-branch.
243 * @param block the block which is entered by the branch
244 * @param cmp the Cmp node expressing the branch condition
245 * @param pnc the Compare relation for taking this branch
246 * @param env statistical environment
248 static void handle_if(ir_node *block, ir_node *cmp, pn_Cmp pnc, env_t *env)
250 ir_node *left = get_Cmp_left(cmp);
251 ir_node *right = get_Cmp_right(cmp);
254 const ir_edge_t *edge, *next;
257 if (is_Bad(left) || is_Bad(right))
260 op = get_irn_op(left);
262 /* Do not create Confirm nodes for Cmp(Const, Const) constructs.
263 These are removed anyway */
264 if (op == op_Const && is_Const(right))
267 /* try to place the constant on the right side for a Confirm */
268 if (op == op_Const || op == op_SymConst) {
274 pnc = get_inversed_pnc(pnc);
278 * First case: both values are identical.
279 * replace the left one by the right (potentially const) one.
281 if (pnc == pn_Cmp_Eq) {
282 cond_block = get_Block_cfgpred_block(block, 0);
283 for (edge = get_irn_out_edge_first(left); edge; edge = next) {
284 ir_node *user = get_edge_src_irn(edge);
285 int pos = get_edge_src_pos(edge);
286 ir_node *blk = get_effective_use_block(user, pos);
288 next = get_irn_out_edge_next(left, edge);
289 if (block_dominates(block, blk)) {
291 * Ok, we found a usage of left in a block
292 * dominated by the branch block.
293 * We can replace the input with right.
295 set_irn_n(user, pos, right);
296 DBG_OPT_CONFIRM(left, right);
298 DB((dbg, LEVEL_2, "Replacing input %d of node %+F with %+F\n", pos, user, right));
301 } else if (block_dominates(blk, cond_block)) {
302 if (is_Const(right) && get_irn_pinned(user) == op_pin_state_floats) {
304 * left == Const and we found a movable user of left in a
305 * dominator of the Cond block
307 const ir_edge_t *edge, *next;
308 for (edge = get_irn_out_edge_first(user); edge; edge = next) {
309 ir_node *usr_of_usr = get_edge_src_irn(edge);
310 int npos = get_edge_src_pos(edge);
311 ir_node *blk = get_effective_use_block(usr_of_usr, npos);
313 next = get_irn_out_edge_next(user, edge);
314 if (block_dominates(block, blk)) {
316 * The user of the user is dominated by our true/false
317 * block. So, create a copy of user WITH the constant
318 * replacing it's pos'th input.
320 * This is always good for unop's and might be good
323 * If user has other user in the false/true block, code
324 * placement will move it down.
325 * If there are users in cond block or upper, we create
326 * "redundant ops", because one will have a const op,
327 * the other no const ...
329 ir_node *new_op = exact_copy(user);
330 set_nodes_block(new_op, block);
331 set_irn_n(new_op, pos, right);
332 set_irn_n(usr_of_usr, npos, new_op);
338 } else { /* not pn_Cmp_Eq cases */
341 foreach_out_edge_safe(left, edge, next) {
342 ir_node *succ = get_edge_src_irn(edge);
343 int pos = get_edge_src_pos(edge);
344 ir_node *blk = get_effective_use_block(succ, pos);
346 if (block_dominates(block, blk)) {
348 * Ok, we found a usage of left in a block
349 * dominated by the branch block.
350 * We can replace the input with a Confirm(left, pnc, right).
353 c = new_r_Confirm(block, left, right, pnc);
355 pos = get_edge_src_pos(edge);
356 set_irn_n(succ, pos, c);
357 DB((dbg, LEVEL_2, "Replacing input %d of node %+F with %+F\n", pos, succ, c));
359 env->num_confirms += 1;
363 if (! is_Const(right)) {
364 /* also construct inverse Confirms */
367 pnc = get_inversed_pnc(pnc);
368 foreach_out_edge_safe(right, edge, next) {
369 ir_node *succ = get_edge_src_irn(edge);
376 pos = get_edge_src_pos(edge);
377 blk = get_effective_use_block(succ, pos);
379 if (block_dominates(block, blk)) {
381 * Ok, we found a usage of right in a block
382 * dominated by the branch block.
383 * We can replace the input with a Confirm(right, pnc^-1, left).
386 rc = new_r_Confirm(block, right, left, pnc);
388 pos = get_edge_src_pos(edge);
389 set_irn_n(succ, pos, rc);
390 DB((dbg, LEVEL_2, "Replacing input %d of node %+F with %+F\n", pos, succ, rc));
392 env->num_confirms += 1;
400 * Pre-block-walker: Called for every block to insert Confirm nodes
402 static void insert_Confirm_in_block(ir_node *block, void *env)
404 ir_node *cond, *proj, *selector;
408 * we can only handle blocks with only ONE control flow
411 if (get_Block_n_cfgpreds(block) != 1)
414 proj = get_Block_cfgpred(block, 0);
418 cond = get_Proj_pred(proj);
422 selector = get_Cond_selector(cond);
423 mode = get_irn_mode(selector);
425 if (mode == mode_b) {
429 handle_modeb(block, selector, get_Proj_proj(proj), env);
431 /* this should be an IF, check this */
432 if (! is_Proj(selector))
435 cmp = get_Proj_pred(selector);
439 pnc = get_Proj_proj(selector);
441 if (get_Proj_proj(proj) != pn_Cond_true) {
442 /* it's the false branch */
443 mode = get_irn_mode(get_Cmp_left(cmp));
444 pnc = get_negated_pnc(pnc, mode);
446 DB((dbg, LEVEL_2, "At %+F using %+F Confirm %=\n", block, cmp, pnc));
448 handle_if(block, cmp, pnc, env);
449 } else if (mode_is_int(mode)) {
450 long proj_nr = get_Proj_proj(proj);
452 /* this is a CASE, but we cannot handle the default case */
453 if (proj_nr == get_Cond_default_proj(cond))
456 handle_case(block, get_Cond_selector(cond), proj_nr, env);
458 } /* insert_Confirm_in_block */
461 * Checks if a node is a non-null Confirm.
463 static int is_non_null_Confirm(const ir_node *ptr)
466 if (! is_Confirm(ptr))
468 if (get_Confirm_cmp(ptr) == pn_Cmp_Lg) {
469 ir_node *bound = get_Confirm_bound(ptr);
471 if (is_Const(bound) && is_Const_null(bound))
474 ptr = get_Confirm_value(ptr);
477 * While a SymConst is not a Confirm, it is non-null
478 * anyway. This helps to reduce the number of
479 * constructed Confirms.
481 if (is_SymConst_addr_ent(ptr))
484 } /* is_non_null_Confirm */
487 * The given pointer will be dereferenced, add non-null Confirms.
489 * @param ptr a node representing an address
490 * @param block the block of the dereferencing instruction
491 * @param env environment
493 static void insert_non_null(ir_node *ptr, ir_node *block, env_t *env)
495 const ir_edge_t *edge, *next;
498 foreach_out_edge_safe(ptr, edge, next) {
499 ir_node *succ = get_edge_src_irn(edge);
504 /* for now, we place a Confirm only in front of a Cmp */
508 pos = get_edge_src_pos(edge);
509 blk = get_effective_use_block(succ, pos);
511 if (block_dominates(block, blk)) {
513 * Ok, we found a usage of ptr in a block
514 * dominated by the Load/Store block.
515 * We can replace the input with a Confirm(ptr, !=, NULL).
518 ir_mode *mode = get_irn_mode(ptr);
519 c = new_Const(get_mode_null(mode));
521 c = new_r_Confirm(block, ptr, c, pn_Cmp_Lg);
524 set_irn_n(succ, pos, c);
525 DB((dbg, LEVEL_2, "Replacing input %d of node %+F with %+F\n", pos, succ, c));
527 env->num_non_null += 1;
528 env->num_confirms += 1;
531 } /* insert_non_null */
534 * Pre-walker: Called for every node to insert Confirm nodes
536 static void insert_Confirm(ir_node *node, void *env)
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);
568 FIRM_DBG_REGISTER(dbg, "firm.ana.confirm");
570 remove_critical_cf_edges(irg);
572 /* we need dominance info */
575 assert(get_irg_pinned(irg) == op_pin_state_pinned &&
576 "Nodes must be placed to insert Confirms");
578 if (! edges_active) {
583 env.num_confirms = 0;
586 env.num_non_null = 0;
588 if (get_opt_global_null_ptr_elimination()) {
589 /* do global NULL test elimination */
590 irg_walk_graph(irg, insert_Confirm, NULL, &env);
592 /* now, visit all blocks and add Confirms where possible */
593 irg_block_walk_graph(irg, insert_Confirm_in_block, NULL, &env);
596 if (env.num_confirms | env.num_consts | env.num_eq) {
597 /* we have add nodes or changed DF edges */
598 set_irg_outs_inconsistent(irg);
600 /* the new nodes are not in the loop info */
601 set_irg_loopinfo_inconsistent(irg);
604 DB((dbg, LEVEL_1, "# Confirms inserted : %u\n", env.num_confirms));
605 DB((dbg, LEVEL_1, "# Const replacements: %u\n", env.num_consts));
606 DB((dbg, LEVEL_1, "# node equalities : %u\n", env.num_eq));
607 DB((dbg, LEVEL_1, "# non-null Confirms : %u\n", env.num_non_null));
609 /* deactivate edges if they where off */
611 edges_deactivate(irg);
612 } /* construct_confirms */
614 /* Construct a pass. */
615 ir_graph_pass_t *construct_confirms_pass(const char *name)
617 return def_graph_pass(name ? name : "confirm", construct_confirms);
618 } /* construct_confirms_pass */
622 * Post-walker: Remove Confirm nodes
624 static void rem_Confirm(ir_node *n, void *env)
628 ir_node *value = get_Confirm_value(n);
633 * Strange: a Confirm is its own bound. This can happen
634 * in dead blocks when Phi nodes are already removed.
636 exchange(n, new_Bad());
643 * Remove all Confirm nodes from a graph.
645 void remove_confirms(ir_graph *irg)
647 int rem = get_opt_remove_confirm();
649 set_opt_remove_confirm(1);
650 optimize_graph_df(irg);
651 set_opt_remove_confirm(rem);
652 } /* remove_confirms */
654 /* Construct a pass. */
655 ir_graph_pass_t *remove_confirms_pass(const char *name)
657 return def_graph_pass(name ? name : "rem_confirm", remove_confirms);
658 } /* remove_confirms_pass */