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 */
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, block, mode, tv, tp);
115 set_irn_n(succ, pos, c);
116 DBG_OPT_CONFIRM_C(irn, c);
117 // ir_printf("1 Replacing input %d of node %n with %n\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(mode_b, 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 %n with %n\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(mode_b, tarval_b_true);
212 ir_node *c_false = new_Const(mode_b, tarval_b_false);
213 c_b = new_r_Confirm(current_ir_graph, cond_block, selector,
214 pnc == pn_Cond_true ? c_true : c_false, pn_Cmp_Eq);
215 c_o = new_r_Confirm(current_ir_graph, cond_block, selector,
216 pnc == pn_Cond_false ? c_true : c_false, pn_Cmp_Eq);
218 for (i = n - 1; i >= 0; --i) {
219 ir_node *pred_blk = get_Block_cfgpred_block(user_blk, i);
221 if (block_dominates(block, pred_blk))
226 phi = new_r_Phi(current_ir_graph, user_blk, n, in, mode_b);
227 set_irn_n(user, pos, phi);
234 * Handle an IF-branch.
236 * @param block the block which is entered by the branch
237 * @param cmp the Cmp node expressing the branch condition
238 * @param pnc the Compare relation for taking this branch
239 * @param env statistical environment
241 static void handle_if(ir_node *block, ir_node *cmp, pn_Cmp pnc, env_t *env) {
242 ir_node *left = get_Cmp_left(cmp);
243 ir_node *right = get_Cmp_right(cmp);
246 const ir_edge_t *edge, *next;
249 if (is_Bad(left) || is_Bad(right))
252 op = get_irn_op(left);
254 /* Do not create Confirm nodes for Cmp(Const, Const) constructs.
255 These are removed anyway */
256 if (op == op_Const && is_Const(right))
259 /* try to place the constant on the right side for a Confirm */
260 if (op == op_Const || op == op_SymConst) {
266 pnc = get_inversed_pnc(pnc);
270 * First case: both values are identical.
271 * replace the left one by the right (potentially const) one.
273 if (pnc == pn_Cmp_Eq) {
274 cond_block = get_Block_cfgpred_block(block, 0);
275 for (edge = get_irn_out_edge_first(left); edge; edge = next) {
276 ir_node *user = get_edge_src_irn(edge);
277 int pos = get_edge_src_pos(edge);
278 ir_node *blk = get_effective_use_block(user, pos);
280 next = get_irn_out_edge_next(left, edge);
281 if (block_dominates(block, blk)) {
283 * Ok, we found a usage of left in a block
284 * dominated by the branch block.
285 * We can replace the input with right.
287 set_irn_n(user, pos, right);
288 DBG_OPT_CONFIRM(left, right);
290 DB((dbg, LEVEL_2, "Replacing input %d of node %n with %n\n", pos, user, right));
293 } else if (block_dominates(blk, cond_block)) {
294 if (is_Const(right) && get_irn_pinned(user) == op_pin_state_floats) {
296 * left == Const and we found a movable user of left in a
297 * dominator of the Cond block
299 const ir_edge_t *edge, *next;
300 for (edge = get_irn_out_edge_first(user); edge; edge = next) {
301 ir_node *usr_of_usr = get_edge_src_irn(edge);
302 int npos = get_edge_src_pos(edge);
303 ir_node *blk = get_effective_use_block(usr_of_usr, npos);
305 next = get_irn_out_edge_next(user, edge);
306 if (block_dominates(block, blk)) {
308 * The user of the user is dominated by our true/false
309 * block. So, create a copy of user WITH the constant
310 * replacing it's pos'th input.
312 * This is always good for unop's and might be good
315 * If user has other user in the false/true block, code
316 * placement will move it down.
317 * If there are users in cond block or upper, we create
318 * "redundant ops", because one will have a const op,
319 * the other no const ...
321 ir_node *new_op = exact_copy(user);
322 set_nodes_block(new_op, block);
323 set_irn_n(new_op, pos, right);
324 set_irn_n(usr_of_usr, npos, new_op);
330 } else { /* not pn_Cmp_Eq cases */
333 for (edge = get_irn_out_edge_first(left); edge; edge = next) {
334 ir_node *succ = get_edge_src_irn(edge);
335 int pos = get_edge_src_pos(edge);
336 ir_node *blk = get_effective_use_block(succ, pos);
338 next = get_irn_out_edge_next(left, edge);
339 if (block_dominates(block, blk)) {
341 * Ok, we found a usage of left in a block
342 * dominated by the branch block.
343 * We can replace the input with a Confirm(left, pnc, right).
346 c = new_r_Confirm(current_ir_graph, block, left, right, pnc);
348 pos = get_edge_src_pos(edge);
349 set_irn_n(succ, pos, c);
350 DB((dbg, LEVEL_2, "Replacing input %d of node %n with %n\n", pos, succ, c));
352 env->num_confirms += 1;
359 * Pre-block-walker: Called for every block to insert Confirm nodes
361 static void insert_Confirm_in_block(ir_node *block, void *env) {
362 ir_node *cond, *proj, *selector;
366 * we can only handle blocks with only ONE control flow
369 if (get_Block_n_cfgpreds(block) != 1)
372 proj = get_Block_cfgpred(block, 0);
376 cond = get_Proj_pred(proj);
380 selector = get_Cond_selector(cond);
381 mode = get_irn_mode(selector);
383 if (mode == mode_b) {
387 handle_modeb(block, selector, get_Proj_proj(proj), env);
389 /* this should be an IF, check this */
390 if (! is_Proj(selector))
393 cmp = get_Proj_pred(selector);
397 pnc = get_Proj_proj(selector);
399 if (get_Proj_proj(proj) != pn_Cond_true) {
400 /* it's the false branch */
401 pnc = get_negated_pnc(pnc, mode);
403 DB((dbg, LEVEL_2, "At %+F using %+F Confirm %=\n", block, cmp, pnc));
405 handle_if(block, cmp, pnc, env);
406 } else if (mode_is_int(mode)) {
407 long proj_nr = get_Proj_proj(proj);
409 /* this is a CASE, but we cannot handle the default case */
410 if (proj_nr == get_Cond_defaultProj(cond))
413 handle_case(block, get_Cond_selector(cond), proj_nr, env);
415 } /* insert_Confirm_in_block */
418 * Checks if a node is a non-null Confirm.
420 static int is_non_null_Confirm(const ir_node *ptr) {
422 * While a SymConst is not a Confirm, it is non-null
423 * anyway. This helps to reduce the number of
424 * constructed Confirms.
426 if (is_SymConst_addr_ent(ptr))
429 if (! is_Confirm(ptr))
431 if (get_Confirm_cmp(ptr) == pn_Cmp_Lg) {
432 ir_node *bound = get_Confirm_bound(ptr);
434 if (is_Const(bound) && is_Const_null(bound))
437 ptr = get_Confirm_value(ptr);
439 } /* is_non_null_Confirm */
442 * The given pointer will be dereferenced, add non-null Confirms.
444 * @param ptr a node representing an address
445 * @param block the block of the dereferencing instruction
446 * @param env environment
448 static void insert_non_null(ir_node *ptr, ir_node *block, env_t *env) {
449 const ir_edge_t *edge, *next;
452 foreach_out_edge_safe(ptr, edge, next) {
453 ir_node *succ = get_edge_src_irn(edge);
458 if (is_Confirm(succ)) {
459 /* beware of loops */
463 if ((is_Load(succ) || is_Store(succ)) &&
464 get_nodes_block(succ) == block) {
465 /* Ignore Loads and Store in the same block for now,
466 because we are not sure if they are dominated.
467 This is not a bad restriction: if exception flow is
468 present, they are in other blocks either. */
472 pos = get_edge_src_pos(edge);
473 blk = get_effective_use_block(succ, pos);
475 if (block_dominates(block, blk) && !is_non_null_Confirm(get_irn_n(succ, pos))) {
477 * Ok, we found a usage of ptr in a block
478 * dominated by the Load/Store block.
479 * We can replace the input with a Confirm(ptr, !=, NULL).
482 ir_mode *mode = get_irn_mode(ptr);
483 c = new_Const(mode, get_mode_null(mode));
485 c = new_r_Confirm(current_ir_graph, block, ptr, c, pn_Cmp_Lg);
488 set_irn_n(succ, pos, c);
489 DB((dbg, LEVEL_2, "Replacing input %d of node %n with %n\n", pos, succ, c));
492 env->num_confirms += 1;
495 } /* insert_non_null */
498 * Pre-walker: Called for every node to insert Confirm nodes
500 static void insert_Confirm(ir_node *node, void *env) {
503 switch (get_irn_opcode(node)) {
505 insert_Confirm_in_block(node, env);
508 ptr = get_Load_ptr(node);
509 if (! is_non_null_Confirm(ptr))
510 insert_non_null(ptr, get_nodes_block(node), env);
513 ptr = get_Store_ptr(node);
514 if (! is_non_null_Confirm(ptr))
515 insert_non_null(ptr, get_nodes_block(node), env);
520 } /* insert_Confirm */
523 * Construct Confirm nodes
525 void construct_confirms(ir_graph *irg) {
527 int edges_active = edges_activated(irg);
530 FIRM_DBG_REGISTER(dbg, "firm.ana.confirm");
532 remove_critical_cf_edges(irg);
534 /* we need dominance info */
537 assert(get_irg_pinned(irg) == op_pin_state_pinned &&
538 "Nodes must be placed to insert Confirms");
540 if (! edges_active) {
545 env.num_confirms = 0;
549 if (get_opt_global_null_ptr_elimination()) {
550 /* do global NULL test elimination */
551 irg_walk_graph(irg, insert_Confirm, NULL, &env);
553 /* now, visit all blocks and add Confirms where possible */
554 irg_block_walk_graph(irg, insert_Confirm_in_block, NULL, &env);
557 if (env.num_confirms | env.num_consts | env.num_eq) {
558 /* we have add nodes or changed DF edges */
559 set_irg_outs_inconsistent(irg);
561 /* the new nodes are not in the loop info */
562 set_irg_loopinfo_inconsistent(irg);
565 DB((dbg, LEVEL_1, "# Confirms inserted : %u\n", env.num_confirms));
566 DB((dbg, LEVEL_1, "# Const replacements: %u\n", env.num_consts));
567 DB((dbg, LEVEL_1, "# node equalities : %u\n", env.num_eq));
569 /* deactivate edges if they where off */
571 edges_deactivate(irg);
572 } /* construct_confirms */
576 * Post-walker: Remove Confirm nodes
578 static void rem_Confirm(ir_node *n, void *env) {
581 ir_node *value = get_Confirm_value(n);
586 * Strange: a Confirm is its own bound. This can happen
587 * in dead blocks when Phi nodes are already removed.
589 exchange(n, new_Bad());
596 * Remove all Confirm nodes from a graph.
598 void remove_confirms(ir_graph *irg) {
599 int rem = get_opt_remove_confirm();
601 set_opt_remove_confirm(1);
602 optimize_graph_df(irg);
603 set_opt_remove_confirm(rem);
604 } /* remove_confirms */