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 Replaces Mux nodes with control-flow
33 #include "irgraph_t.h"
40 typedef struct walk_env {
41 lower_mux_callback *cb_func;
45 static void find_mux_nodes(ir_node *mux, void *ctx)
47 walk_env_t *env = ctx;
49 /* Skip non-mux nodes. */
53 /* Skip nodes, depending on the callback function. */
54 if (env->cb_func != NULL && !env->cb_func(mux)) {
59 ARR_APP1(ir_node*, env->muxes, mux);
62 static void lower_mux_node(ir_node* mux)
71 ir_node *mux_values[2];
75 irg = get_irn_irg(mux);
77 /* Split the block in two halfs, with the mux in the upper block. */
78 lower_block = get_nodes_block(mux);
79 assert(lower_block != 0);
81 upper_block = get_nodes_block(mux);
83 /* Create a cond node with two projs and a phi as mux replacement. The
84 * true proj jumps directly to the lower block, the false proj uses a
85 * block in-between, so that the phi can be used to select the result
86 * value from the old mux node in the lower block. */
87 cond = new_r_Cond(upper_block, get_Mux_sel(mux));
88 trueProj = new_r_Proj(upper_block, cond, mode_X, pn_Cond_true);
89 falseProj = new_r_Proj(upper_block, cond, mode_X, pn_Cond_false);
90 falseBlock = new_r_Block(irg, 1, &falseProj);
91 mux_jmps[0] = trueProj;
92 mux_jmps[1] = new_r_Jmp(falseBlock);
94 /* Kill the jump from upper to lower block and replace the in array. */
95 assert(get_Block_n_cfgpreds(lower_block) == 1);
96 kill_node(get_Block_cfgpred(lower_block, 0));
97 set_irn_in(lower_block, 2, mux_jmps);
99 /* Combine the two control flows with a phi to select the correct value
100 * and use it to replace the mux. */
101 mux_values[0] = get_Mux_true(mux);
102 mux_values[1] = get_Mux_false(mux);
103 phi = new_r_Phi(lower_block, 2, mux_values, get_irn_mode(mux));
106 /* Add links and update phi node lists, for the next part_block() call.
107 * lower_block and upper_block have been updated by part_block(). Link
108 * the projs with the cond. */
109 set_irn_link(trueProj, get_irn_link(cond));
110 set_irn_link(falseProj, trueProj);
111 set_irn_link(cond, falseProj);
113 add_Block_phi(lower_block, phi);
116 void lower_mux(ir_graph *irg, lower_mux_callback *cb_func)
121 /* Scan the graph for mux nodes to lower. */
122 env.cb_func = cb_func;
123 env.muxes = NEW_ARR_F(ir_node*, 0);
124 irg_walk_graph(irg, find_mux_nodes, 0, &env);
126 n_muxes = ARR_LEN(env.muxes);
128 ir_resources_t resources = IR_RESOURCE_IRN_LINK | IR_RESOURCE_PHI_LIST;
130 /* This is required by part_block() later. */
131 ir_reserve_resources(irg, resources);
132 collect_phiprojs(irg);
134 for (i = 0; i < n_muxes; ++i) {
135 lower_mux_node(env.muxes[i]);
138 /* Cleanup, verify the graph. */
139 ir_free_resources(irg, resources);
141 set_irg_outs_inconsistent(irg);
142 set_irg_doms_inconsistent(irg);
143 set_irg_extblk_inconsistent(irg);
144 set_irg_loopinfo_inconsistent(irg);
146 DEL_ARR_F(env.muxes);
150 ir_graph_pass_t pass;
151 lower_mux_callback *cb_func;
155 * Wrapper to run ir_lower_mux() as an ir_graph pass
157 static int pass_wrapper(ir_graph *irg, void *context)
159 struct pass_t *pass = context;
161 lower_mux(irg, pass->cb_func);
165 ir_graph_pass_t *lower_mux_pass(const char *name, lower_mux_callback *cb_func)
167 struct pass_t *pass = XMALLOCZ(struct pass_t);
169 pass->cb_func = cb_func;
170 return def_graph_pass_constructor(
171 &pass->pass, name ? name : "lower_mux", pass_wrapper);