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"
43 typedef struct _env_t {
44 unsigned num_confirms; /**< number of inserted Confirm nodes */
45 unsigned num_consts; /**< number of constants placed */
46 unsigned num_eq; /**< number of equalities placed */
50 * Return the effective use block of a node and it's predecessor on
53 * @param node the node
54 * @param pos the position of the used input
56 * This handles correctly Phi nodes.
58 static ir_node *get_effective_use_block(ir_node *node, int pos) {
59 /* the effective use of a Phi is in its predecessor block */
61 return get_nodes_block(get_irn_n(node, pos));
63 return get_nodes_block(node);
67 * Handle a CASE-branch.
69 * @param block the block which is entered by the branch
70 * @param irn the node expressing the switch value
71 * @param nr the branch label
72 * @param env statistical environment
74 * Branch labels are a simple case. We can replace the value
75 * by a Const with the branch label.
77 static void handle_case(ir_node *block, ir_node *irn, long nr, env_t *env) {
78 const ir_edge_t *edge, *next;
84 for (edge = get_irn_out_edge_first(irn); edge; edge = next) {
85 ir_node *succ = get_edge_src_irn(edge);
86 int pos = get_edge_src_pos(edge);
87 ir_node *blk = get_effective_use_block(succ, pos);
89 next = get_irn_out_edge_next(irn, edge);
91 if (block_dominates(block, blk)) {
93 * Ok, we found a user of irn that is placed
94 * in a block dominated by the branch block.
95 * We can replace the input with the Constant
100 ir_mode *mode = get_irn_mode(irn);
101 ir_type *tp = get_irn_type(irn);
102 tarval *tv = new_tarval_from_long(nr, mode);
103 c = new_r_Const_type(current_ir_graph, block, mode, tv, tp);
106 set_irn_n(succ, pos, c);
107 DBG_OPT_CONFIRM_C(irn, c);
108 // ir_printf("1 Replacing input %d of node %n with %n\n", pos, succ, c);
110 env->num_consts += 1;
116 * Handle an IF-branch.
118 * @param block the block which is entered by the branch
119 * @param cmp the Cmp node expressing the branch condition
120 * @param pnc the Compare relation for taking this branch
121 * @param env statistical environment
123 static void handle_if(ir_node *block, ir_node *cmp, pn_Cmp pnc, env_t *env) {
124 ir_node *left = get_Cmp_left(cmp);
125 ir_node *right = get_Cmp_right(cmp);
128 const ir_edge_t *edge, *next;
131 if (is_Bad(left) ||is_Bad(right))
134 op = get_irn_op(left);
136 /* Do not create Confirm nodes for Cmp(Const, Const) constructs.
137 These are removed anyway */
138 if (op == op_Const && is_Const(right))
141 /* try to place the constant on the right side for a Confirm */
142 if (op == op_Const || op == op_SymConst) {
148 pnc = get_inversed_pnc(pnc);
152 * First case: both values are identical.
153 * replace the left one by the right (potentially const) one.
155 if (pnc == pn_Cmp_Eq) {
156 cond_block = get_Block_cfgpred_block(block, 0);
157 for (edge = get_irn_out_edge_first(left); edge; edge = next) {
158 ir_node *user = get_edge_src_irn(edge);
159 int pos = get_edge_src_pos(edge);
160 ir_node *blk = get_effective_use_block(user, pos);
162 next = get_irn_out_edge_next(left, edge);
163 if (block_dominates(block, blk)) {
165 * Ok, we found a usage of left in a block
166 * dominated by the branch block.
167 * We can replace the input with right.
169 set_irn_n(user, pos, right);
170 DBG_OPT_CONFIRM(left, right);
172 // ir_printf("2 Replacing input %d of node %n with %n\n", pos, user, right);
175 } else if (block_dominates(blk, cond_block)) {
176 if (is_Const(right) && get_irn_pinned(user) == op_pin_state_floats) {
178 * left == Const and we found a movable user of left in a
179 * dominator of the Cond block
181 const ir_edge_t *edge, *next;
182 for (edge = get_irn_out_edge_first(user); edge; edge = next) {
183 ir_node *usr_of_usr = get_edge_src_irn(edge);
184 int npos = get_edge_src_pos(edge);
185 ir_node *blk = get_effective_use_block(usr_of_usr, npos);
187 next = get_irn_out_edge_next(user, edge);
188 if (block_dominates(block, blk)) {
190 * The user of the user is dominated by our true/false
191 * block. So, create a copy of user WITH the constant
192 * replacing it's pos'th input.
194 * This is always good for unop's and might be good
197 * If user has other user in the false/true block, code
198 * placement will move it down.
199 * If there are users in cond block or upper, we create
200 * "redundant ops", because one will have a const op,
201 * the other no const ...
203 ir_node *new_op = exact_copy(user);
204 set_nodes_block(new_op, block);
205 set_irn_n(new_op, pos, right);
206 set_irn_n(usr_of_usr, npos, new_op);
212 } else { /* not pn_Cmp_Eq cases */
215 for (edge = get_irn_out_edge_first(left); edge; edge = next) {
216 ir_node *succ = get_edge_src_irn(edge);
217 int pos = get_edge_src_pos(edge);
218 ir_node *blk = get_effective_use_block(succ, pos);
220 next = get_irn_out_edge_next(left, edge);
221 if (block_dominates(block, blk)) {
223 * Ok, we found a usage of left in a block
224 * dominated by the branch block.
225 * We can replace the input with a Confirm(left, pnc, right).
228 c = new_r_Confirm(current_ir_graph, block, left, right, pnc);
230 pos = get_edge_src_pos(edge);
231 set_irn_n(succ, pos, c);
232 // ir_printf("3 Replacing input %d of node %n with %n\n", pos, user, c);
234 env->num_confirms += 1;
241 * Pre-walker: Called for every block to insert Confirm nodes
243 static void insert_Confirm(ir_node *block, void *env) {
244 ir_node *cond, *proj, *selector;
248 * we can only handle blocks with only ONE control flow
251 if (get_Block_n_cfgpreds(block) != 1)
254 proj = get_Block_cfgpred(block, 0);
255 if (get_irn_op(proj) != op_Proj)
258 cond = get_Proj_pred(proj);
259 if (get_irn_op(cond) != op_Cond)
262 selector = get_Cond_selector(cond);
263 mode = get_irn_mode(selector);
265 if (mode == mode_b) {
269 /* this should be an IF, check this */
270 if (get_irn_op(selector) != op_Proj)
273 cmp = get_Proj_pred(selector);
274 if (get_irn_op(cmp) != op_Cmp)
277 pnc = get_Proj_proj(selector);
279 if (get_Proj_proj(proj) != pn_Cond_true) {
280 /* it's the false branch */
281 pnc = get_negated_pnc(pnc, mode);
283 // ir_printf("At %n using %n Confirm %=\n", block, cmp, pnc);
285 handle_if(block, cmp, pnc, env);
286 } else if (mode_is_int(mode)) {
287 long proj_nr = get_Proj_proj(proj);
289 /* this is a CASE, but we cannot handle the default case */
290 if (proj_nr == get_Cond_defaultProj(cond))
293 handle_case(block, get_Cond_selector(cond), proj_nr, env);
295 } /* insert_Confirm */
298 * Construct Confirm nodes
300 void construct_confirms(ir_graph *irg) {
302 int edges_active = edges_activated(irg);
304 /* we need dominance info */
307 assert(get_irg_pinned(irg) == op_pin_state_pinned &&
308 "Nodes must be placed to insert Confirms");
310 if (! edges_active) {
315 env.num_confirms = 0;
319 /* now, visit all blocks and add Confirms where possible */
320 irg_block_walk_graph(irg, insert_Confirm, NULL, &env);
322 if (env.num_confirms | env.num_consts | env.num_eq) {
323 /* we have add nodes or changed DF edges */
324 set_irg_outs_inconsistent(irg);
326 /* the new nodes are not in the loop info */
327 set_irg_loopinfo_inconsistent(irg);
331 printf("# Confirms inserted : %u\n", env.num_confirms);
332 printf("# Const replacements: %u\n", env.num_consts);
333 printf("# node equalities : %u\n", env.num_eq);
336 /* deactivate edges if they where off */
338 edges_deactivate(irg);
339 } /* construct_confirms */
342 * Post-walker: Remove Confirm nodes
344 static void rem_Confirm(ir_node *n, void *env) {
346 if (get_irn_op(n) == op_Confirm) {
347 ir_node *value = get_Confirm_value(n);
352 * Strange: a Confirm is it's own bound. This can happen
353 * in dead blocks when Phi nodes are already removed.
355 exchange(n, new_Bad());
361 * Remove all Confirm nodes from a graph.
363 void remove_confirms(ir_graph *irg) {
364 irg_walk_graph(irg, NULL, rem_Confirm, NULL);
365 } /* remove_confirms */