2 * This file is part of libFirm.
3 * Copyright (C) 2012 University of Karlsruhe.
8 * @brief Construction of Confirm nodes
14 #include "irconsconfirm.h"
16 #include "irgraph_t.h"
20 #include "iropt_dbg.h"
21 #include "iredges_t.h"
35 typedef struct env_t {
36 unsigned num_confirms; /**< Number of inserted Confirm nodes. */
37 unsigned num_consts; /**< Number of constants placed. */
38 unsigned num_eq; /**< Number of equalities placed. */
39 unsigned num_non_null; /**< Number of non-null Confirms. */
42 /** The debug handle. */
43 DEBUG_ONLY(static firm_dbg_module_t *dbg;)
46 * Return the effective use block of a node and its predecessor on
49 * @param node the node
50 * @param pos the position of the used input
52 * This handles correctly Phi nodes.
54 static ir_node *get_effective_use_block(ir_node *node, int pos)
57 /* the effective use of a Phi argument is in its predecessor block */
58 node = get_nodes_block(node);
59 return get_Block_cfgpred_block(node, pos);
61 return get_nodes_block(node);
64 static ir_node *get_case_value(ir_node *switchn, long pn)
66 ir_graph *irg = get_irn_irg(switchn);
67 const ir_switch_table *table = get_Switch_table(switchn);
68 size_t n_entries = ir_switch_table_get_n_entries(table);
69 ir_tarval *val = NULL;
71 for (e = 0; e < n_entries; ++e) {
72 const ir_switch_table_entry *entry
73 = ir_switch_table_get_entry_const(table, e);
76 /* multiple matching entries gets too complicated for a single
80 /* case ranges are too complicated too */
81 if (entry->min != entry->max)
86 return new_r_Const(irg, val);
90 * Handle a CASE-branch.
92 * Branch labels are a simple case. We can replace the value
93 * by a Const with the branch label.
95 static void handle_case(ir_node *block, ir_node *switchn, long pn, env_t *env)
98 ir_node *selector = get_Switch_selector(switchn);
100 /* we can't do usefull things with the default label */
101 if (pn == pn_Switch_default)
104 foreach_out_edge_safe(selector, edge) {
105 ir_node *succ = get_edge_src_irn(edge);
106 int pos = get_edge_src_pos(edge);
107 ir_node *blk = get_effective_use_block(succ, pos);
109 if (block_dominates(block, blk)) {
111 * Ok, we found a user of irn that is placed
112 * in a block dominated by the branch block.
113 * We can replace the input with the Constant
117 c = get_case_value(switchn, pn);
119 set_irn_n(succ, pos, c);
120 DBG_OPT_CONFIRM_C(selector, 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;
141 foreach_out_edge_safe(selector, edge) {
142 ir_node *user = get_edge_src_irn(edge);
143 int pos = get_edge_src_pos(edge);
144 ir_node *user_blk = get_effective_use_block(user, pos);
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 ir_graph *irg = get_irn_irg(block);
154 con = new_r_Const(irg, pnc == pn_Cond_true ? tarval_b_true : tarval_b_false);
156 old = get_irn_n(user, pos);
157 set_irn_n(user, pos, con);
158 DBG_OPT_CONFIRM_C(old, con);
160 DB((dbg, LEVEL_2, "Replacing input %d of node %+F with %+F\n", pos, user, con));
162 env->num_consts += 1;
166 /* get the other block */
167 if (other_blk == NULL) {
168 /* we have already tested, that block has only ONE Cond predecessor */
169 cond = get_Proj_pred(get_Block_cfgpred(block, 0));
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_graph *irg = get_irn_irg(block);
215 ir_node *c_true = new_r_Const(irg, tarval_b_true);
216 ir_node *c_false = new_r_Const(irg, tarval_b_false);
217 env->num_consts += 2;
218 if (pnc == pn_Cond_true) {
226 for (i = n - 1; i >= 0; --i) {
227 ir_node *pred_blk = get_Block_cfgpred_block(user_blk, i);
229 if (block_dominates(block, pred_blk))
234 phi = new_r_Phi(user_blk, n, in, mode_b);
235 set_irn_n(user, pos, phi);
243 * Handle an IF-branch.
245 * @param block the block which is entered by the branch
246 * @param cmp the Cmp node expressing the branch condition
247 * @param rel the Compare relation for taking this branch
248 * @param env statistical environment
250 static void handle_if(ir_node *block, ir_node *cmp, ir_relation rel, env_t *env)
252 ir_node *left = get_Cmp_left(cmp);
253 ir_node *right = get_Cmp_right(cmp);
257 if (is_Bad(left) || is_Bad(right))
260 /* Do not create Confirm nodes for Cmp(Const, Const) constructs.
261 These are removed anyway */
262 if (is_Const(left) && is_Const(right))
265 /* try to place the constant on the right side for a Confirm */
266 if (is_Const(left) || is_SymConst(left)) {
272 rel = get_inversed_relation(rel);
276 * First case: both values are identical.
277 * replace the left one by the right (potentially const) one.
279 if (rel == ir_relation_equal) {
280 cond_block = get_Block_cfgpred_block(block, 0);
281 foreach_out_edge_safe(left, edge) {
282 ir_node *user = get_edge_src_irn(edge);
283 int pos = get_edge_src_pos(edge);
284 ir_node *blk = get_effective_use_block(user, pos);
286 if (block_dominates(block, blk)) {
288 * Ok, we found a usage of left in a block
289 * dominated by the branch block.
290 * We can replace the input with right.
292 set_irn_n(user, pos, right);
293 DBG_OPT_CONFIRM(left, right);
295 DB((dbg, LEVEL_2, "Replacing input %d of node %+F with %+F\n", pos, user, right));
298 } else if (block_dominates(blk, cond_block)
300 && get_irn_pinned(user) == op_pin_state_floats) {
302 * left == Const and we found a movable user of left in a
303 * dominator of the Cond block
305 foreach_out_edge_safe(user, user_edge) {
306 ir_node *usr_of_usr = get_edge_src_irn(user_edge);
307 int npos = get_edge_src_pos(user_edge);
308 ir_node *user_blk = get_effective_use_block(usr_of_usr, npos);
310 if (block_dominates(block, user_blk)) {
312 * The user of the user is dominated by our true/false
313 * block. So, create a copy of user WITH the constant
314 * replacing its pos'th input.
316 * This is always good for unop's and might be good
319 * If user has other user in the false/true block, code
320 * placement will move it down.
321 * If there are users in cond block or upper, we create
322 * "redundant ops", because one will have a const op,
323 * the other no const ...
325 ir_node *new_op = exact_copy(user);
326 set_nodes_block(new_op, block);
327 set_irn_n(new_op, pos, right);
328 set_irn_n(usr_of_usr, npos, new_op);
334 } else { /* not ir_relation_equal cases */
337 foreach_out_edge_safe(left, edge) {
338 ir_node *succ = get_edge_src_irn(edge);
339 int pos = get_edge_src_pos(edge);
340 ir_node *blk = get_effective_use_block(succ, pos);
342 if (block_dominates(block, blk)) {
344 * Ok, we found a usage of left in a block
345 * dominated by the branch block.
346 * We can replace the input with a Confirm(left, pnc, right).
349 c = new_r_Confirm(block, left, right, rel);
351 pos = get_edge_src_pos(edge);
352 set_irn_n(succ, pos, c);
353 DB((dbg, LEVEL_2, "Replacing input %d of node %+F with %+F\n", pos, succ, c));
355 env->num_confirms += 1;
359 if (! is_Const(right)) {
360 /* also construct inverse Confirms */
363 rel = get_inversed_relation(rel);
364 foreach_out_edge_safe(right, edge) {
365 ir_node *succ = get_edge_src_irn(edge);
372 pos = get_edge_src_pos(edge);
373 blk = get_effective_use_block(succ, pos);
375 if (block_dominates(block, blk)) {
377 * Ok, we found a usage of right in a block
378 * dominated by the branch block.
379 * We can replace the input with a Confirm(right, rel^-1, left).
382 rc = new_r_Confirm(block, right, left, rel);
384 pos = get_edge_src_pos(edge);
385 set_irn_n(succ, pos, rc);
386 DB((dbg, LEVEL_2, "Replacing input %d of node %+F with %+F\n", pos, succ, rc));
388 env->num_confirms += 1;
396 * Pre-block-walker: Called for every block to insert Confirm nodes
398 static void insert_Confirm_in_block(ir_node *block, void *data)
400 env_t *env = (env_t*) data;
405 * we can only handle blocks with only ONE control flow
408 if (get_Block_n_cfgpreds(block) != 1)
411 proj = get_Block_cfgpred(block, 0);
415 cond = get_Proj_pred(proj);
416 if (is_Switch(cond)) {
417 long proj_nr = get_Proj_proj(proj);
418 handle_case(block, cond, proj_nr, env);
419 } else if (is_Cond(cond)) {
420 ir_node *selector = get_Cond_selector(cond);
423 handle_modeb(block, selector, (pn_Cond) get_Proj_proj(proj), env);
425 if (! is_Cmp(selector))
428 rel = get_Cmp_relation(selector);
430 if (get_Proj_proj(proj) != pn_Cond_true) {
431 /* it's the false branch */
432 rel = get_negated_relation(rel);
434 DB((dbg, LEVEL_2, "At %+F using %+F Confirm %=\n", block, selector, rel));
436 handle_if(block, selector, rel, env);
441 * Checks if a node is a non-null Confirm.
443 static int is_non_null_Confirm(const ir_node *ptr)
446 if (! is_Confirm(ptr))
448 if (get_Confirm_relation(ptr) == ir_relation_less_greater) {
449 ir_node *bound = get_Confirm_bound(ptr);
451 if (is_Const(bound) && is_Const_null(bound))
454 ptr = get_Confirm_value(ptr);
457 * While a SymConst is not a Confirm, it is non-null
458 * anyway. This helps to reduce the number of
459 * constructed Confirms.
461 if (is_SymConst_addr_ent(ptr))
467 * The given pointer will be dereferenced, add non-null Confirms.
469 * @param ptr a node representing an address
470 * @param block the block of the dereferencing instruction
471 * @param env environment
473 static void insert_non_null(ir_node *ptr, ir_node *block, env_t *env)
477 foreach_out_edge_safe(ptr, edge) {
478 ir_node *succ = get_edge_src_irn(edge);
483 /* for now, we place a Confirm only in front of a Cmp */
487 pos = get_edge_src_pos(edge);
488 blk = get_effective_use_block(succ, pos);
490 if (block_dominates(block, blk)) {
492 * Ok, we found a usage of ptr in a block
493 * dominated by the Load/Store block.
494 * We can replace the input with a Confirm(ptr, !=, NULL).
497 ir_mode *mode = get_irn_mode(ptr);
498 ir_graph *irg = get_irn_irg(block);
499 c = new_r_Const(irg, get_mode_null(mode));
500 c = new_r_Confirm(block, ptr, c, ir_relation_less_greater);
503 set_irn_n(succ, pos, c);
504 DB((dbg, LEVEL_2, "Replacing input %d of node %+F with %+F\n", pos, succ, c));
506 env->num_non_null += 1;
507 env->num_confirms += 1;
513 * Pre-walker: Called for every node to insert Confirm nodes
515 static void insert_Confirm(ir_node *node, void *data)
518 env_t *env = (env_t*) data;
520 switch (get_irn_opcode(node)) {
522 insert_Confirm_in_block(node, env);
525 ptr = get_Load_ptr(node);
526 if (! is_non_null_Confirm(ptr))
527 insert_non_null(ptr, get_nodes_block(node), env);
530 ptr = get_Store_ptr(node);
531 if (! is_non_null_Confirm(ptr))
532 insert_non_null(ptr, get_nodes_block(node), env);
539 void construct_confirms(ir_graph *irg)
542 FIRM_DBG_REGISTER(dbg, "firm.ana.confirm");
544 assure_irg_properties(irg,
545 IR_GRAPH_PROPERTY_CONSISTENT_OUT_EDGES
546 | IR_GRAPH_PROPERTY_CONSISTENT_DOMINANCE
547 | IR_GRAPH_PROPERTY_NO_CRITICAL_EDGES);
549 assert(get_irg_pinned(irg) == op_pin_state_pinned &&
550 "Nodes must be placed to insert Confirms");
552 env.num_confirms = 0;
555 env.num_non_null = 0;
557 if (get_opt_global_null_ptr_elimination()) {
558 /* do global NULL test elimination */
559 irg_walk_graph(irg, insert_Confirm, NULL, &env);
561 /* now, visit all blocks and add Confirms where possible */
562 irg_block_walk_graph(irg, insert_Confirm_in_block, NULL, &env);
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));
568 DB((dbg, LEVEL_1, "# non-null Confirms : %u\n", env.num_non_null));
570 confirm_irg_properties(irg, IR_GRAPH_PROPERTIES_CONTROL_FLOW);
573 ir_graph_pass_t *construct_confirms_pass(const char *name)
575 return def_graph_pass(name ? name : "confirm", construct_confirms);
578 static void remove_confirm(ir_node *n, void *env)
586 value = get_Confirm_value(n);
590 void remove_confirms(ir_graph *irg)
592 irg_walk_graph(irg, NULL, remove_confirm, NULL);
593 confirm_irg_properties(irg, IR_GRAPH_PROPERTIES_CONTROL_FLOW);
596 ir_graph_pass_t *remove_confirms_pass(const char *name)
598 return def_graph_pass(name ? name : "rem_confirm", remove_confirms);