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 Register pressure node selector.
23 * @author Sebastian Hack
30 #include "iredges_t.h"
36 #include "belistsched.h"
41 typedef struct usage_stats_t {
43 struct usage_stats_t *next;
45 int uses_in_block; /**< Number of uses inside the current block. */
46 int already_consumed; /**< Number of insns using this value already
53 ir_nodeset_t already_scheduled;
54 } reg_pressure_selector_env_t;
57 static inline usage_stats_t *get_or_set_usage_stats(reg_pressure_selector_env_t *env, ir_node *irn)
59 usage_stats_t *us = (usage_stats_t*)get_irn_link(irn);
62 us = OALLOC(&env->obst, usage_stats_t);
64 us->already_consumed = 0;
65 us->max_hops = INT_MAX;
68 set_irn_link(irn, us);
74 static inline usage_stats_t *get_usage_stats(ir_node *irn)
76 usage_stats_t *us = (usage_stats_t*)get_irn_link(irn);
77 assert(us && "This node must have usage stats");
81 static int max_hops_walker(reg_pressure_selector_env_t *env, ir_node *irn, ir_node *curr_bl, int depth, unsigned visited_nr)
83 ir_node *bl = get_nodes_block(irn);
85 * If the reached node is not in the block desired,
86 * return the value passed for this situation.
88 if (get_nodes_block(irn) != bl)
89 return block_dominates(bl, curr_bl) ? 0 : INT_MAX;
92 * If the node is in the current block but not
93 * yet scheduled, we keep on searching from that node.
95 if (!ir_nodeset_contains(&env->already_scheduled, irn)) {
98 for (i = 0, n = get_irn_ins_or_deps(irn); i < n; ++i) {
99 ir_node *operand = get_irn_in_or_dep(irn, i);
101 if (get_irn_visited(operand) < visited_nr) {
104 set_irn_visited(operand, visited_nr);
105 tmp = max_hops_walker(env, operand, bl, depth + 1, visited_nr);
114 * If the node is in the current block and scheduled, return
115 * the depth which indicates the number of steps to the
116 * region of scheduled nodes.
121 static int compute_max_hops(reg_pressure_selector_env_t *env, ir_node *irn)
123 ir_node *bl = get_nodes_block(irn);
124 ir_graph *irg = get_irn_irg(bl);
127 foreach_out_edge(irn, edge) {
128 ir_node *user = get_edge_src_irn(edge);
129 unsigned visited_nr = get_irg_visited(irg) + 1;
132 set_irg_visited(irg, visited_nr);
133 max_hops = max_hops_walker(env, user, irn, 0, visited_nr);
134 res = MAX(res, max_hops);
140 static void *reg_pressure_graph_init(ir_graph *irg)
142 irg_walk_graph(irg, firm_clear_link, NULL, NULL);
147 static void *reg_pressure_block_init(void *graph_env, ir_node *bl)
149 reg_pressure_selector_env_t *env = XMALLOC(reg_pressure_selector_env_t);
152 obstack_init(&env->obst);
153 ir_nodeset_init(&env->already_scheduled);
157 * Collect usage statistics.
159 sched_foreach(bl, irn) {
160 for (int i = 0, n = get_irn_arity(irn); i < n; ++i) {
161 usage_stats_t *us = get_or_set_usage_stats(env, irn);
169 static void reg_pressure_block_free(void *block_env)
171 reg_pressure_selector_env_t *env = (reg_pressure_selector_env_t*)block_env;
174 for (us = env->root; us; us = us->next)
175 set_irn_link(us->irn, NULL);
177 obstack_free(&env->obst, NULL);
178 ir_nodeset_destroy(&env->already_scheduled);
182 static int get_result_hops_sum(reg_pressure_selector_env_t *env, ir_node *irn)
185 if (get_irn_mode(irn) == mode_T) {
186 foreach_out_edge(irn, edge)
187 res += get_result_hops_sum(env, get_edge_src_irn(edge));
190 else if (mode_is_data(get_irn_mode(irn)))
191 res = compute_max_hops(env, irn);
197 static inline int reg_pr_costs(reg_pressure_selector_env_t *env, ir_node *irn)
202 for (i = 0, n = get_irn_arity(irn); i < n; ++i) {
203 ir_node *op = get_irn_n(irn, i);
206 || (arch_get_irn_flags(op) & arch_irn_flags_not_scheduled))
209 sum += compute_max_hops(env, op);
212 sum += get_result_hops_sum(env, irn);
217 static ir_node *reg_pressure_select(void *block_env, ir_nodeset_t *ready_set)
219 reg_pressure_selector_env_t *env = (reg_pressure_selector_env_t*)block_env;
221 int curr_cost = INT_MAX;
223 assert(ir_nodeset_size(ready_set) > 0);
225 foreach_ir_nodeset(ready_set, irn, iter) {
227 Ignore branch instructions for the time being.
228 They should only be scheduled if there is nothing else.
231 int costs = reg_pr_costs(env, irn);
232 if (costs <= curr_cost) {
240 There was no result so we only saw a branch.
245 res = ir_nodeset_first(ready_set);
246 assert(res && "There must be a node scheduled.");
249 ir_nodeset_insert(&env->already_scheduled, res);
253 static void sched_reg_pressure(ir_graph *irg)
255 static const list_sched_selector_t reg_pressure_selector = {
256 reg_pressure_graph_init,
257 reg_pressure_block_init,
259 NULL, /* node_ready */
260 NULL, /* node_selected */
261 reg_pressure_block_free,
264 be_list_sched_graph(irg, ®_pressure_selector);
267 BE_REGISTER_MODULE_CONSTRUCTOR(be_init_sched_regpress)
268 void be_init_sched_regpress(void)
270 be_register_scheduler("regpress", sched_reg_pressure);