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
31 #include "iredges_t.h"
37 #include "belistsched.h"
42 typedef struct usage_stats_t {
44 struct usage_stats_t *next;
46 int uses_in_block; /**< Number of uses inside the current block. */
47 int already_consumed; /**< Number of insns using this value already
54 ir_nodeset_t already_scheduled;
55 } reg_pressure_selector_env_t;
60 * Ugly global variable for the compare function
61 * since qsort(3) does not pass an extra pointer.
63 static ir_node *curr_bl = NULL;
65 static int cmp_usage(const void *a, const void *b)
67 struct trivial_sched_env *env;
72 res = is_live_end(env->curr_bl, a) - is_live_end(env->curr_bl, b);
75 * One of them is live at the end of the block.
76 * Then, that one shall be scheduled at after the other
86 static inline usage_stats_t *get_or_set_usage_stats(reg_pressure_selector_env_t *env, ir_node *irn)
88 usage_stats_t *us = (usage_stats_t*)get_irn_link(irn);
91 us = OALLOC(&env->obst, usage_stats_t);
93 us->already_consumed = 0;
94 us->max_hops = INT_MAX;
97 set_irn_link(irn, us);
103 static inline usage_stats_t *get_usage_stats(ir_node *irn)
105 usage_stats_t *us = (usage_stats_t*)get_irn_link(irn);
106 assert(us && "This node must have usage stats");
110 static int max_hops_walker(reg_pressure_selector_env_t *env, ir_node *irn, ir_node *curr_bl, int depth, unsigned visited_nr)
112 ir_node *bl = get_nodes_block(irn);
114 * If the reached node is not in the block desired,
115 * return the value passed for this situation.
117 if (get_nodes_block(irn) != bl)
118 return block_dominates(bl, curr_bl) ? 0 : INT_MAX;
121 * If the node is in the current block but not
122 * yet scheduled, we keep on searching from that node.
124 if (!ir_nodeset_contains(&env->already_scheduled, irn)) {
127 for (i = 0, n = get_irn_ins_or_deps(irn); i < n; ++i) {
128 ir_node *operand = get_irn_in_or_dep(irn, i);
130 if (get_irn_visited(operand) < visited_nr) {
133 set_irn_visited(operand, visited_nr);
134 tmp = max_hops_walker(env, operand, bl, depth + 1, visited_nr);
143 * If the node is in the current block and scheduled, return
144 * the depth which indicates the number of steps to the
145 * region of scheduled nodes.
150 static int compute_max_hops(reg_pressure_selector_env_t *env, ir_node *irn)
152 ir_node *bl = get_nodes_block(irn);
153 ir_graph *irg = get_irn_irg(bl);
156 const ir_edge_t *edge;
158 foreach_out_edge(irn, edge) {
159 ir_node *user = get_edge_src_irn(edge);
160 unsigned visited_nr = get_irg_visited(irg) + 1;
163 set_irg_visited(irg, visited_nr);
164 max_hops = max_hops_walker(env, user, irn, 0, visited_nr);
165 res = MAX(res, max_hops);
171 static void *reg_pressure_graph_init(ir_graph *irg)
173 irg_walk_graph(irg, firm_clear_link, NULL, NULL);
178 static void *reg_pressure_block_init(void *graph_env, ir_node *bl)
181 reg_pressure_selector_env_t *env = XMALLOC(reg_pressure_selector_env_t);
184 obstack_init(&env->obst);
185 ir_nodeset_init(&env->already_scheduled);
189 * Collect usage statistics.
191 sched_foreach(bl, irn) {
194 || (arch_get_irn_flags(irn) & arch_irn_flags_not_scheduled))
197 for (i = 0, n = get_irn_arity(irn); i < n; ++i) {
198 usage_stats_t *us = get_or_set_usage_stats(env, irn);
199 #if 0 /* Liveness is not computed here! */
200 if (is_live_end(bl, op))
201 us->uses_in_block = 99999;
211 static void reg_pressure_block_free(void *block_env)
213 reg_pressure_selector_env_t *env = (reg_pressure_selector_env_t*)block_env;
216 for (us = env->root; us; us = us->next)
217 set_irn_link(us->irn, NULL);
219 obstack_free(&env->obst, NULL);
220 ir_nodeset_destroy(&env->already_scheduled);
224 static int get_result_hops_sum(reg_pressure_selector_env_t *env, ir_node *irn)
227 if (get_irn_mode(irn) == mode_T) {
228 const ir_edge_t *edge;
230 foreach_out_edge(irn, edge)
231 res += get_result_hops_sum(env, get_edge_src_irn(edge));
234 else if (mode_is_data(get_irn_mode(irn)))
235 res = compute_max_hops(env, irn);
241 static inline int reg_pr_costs(reg_pressure_selector_env_t *env, ir_node *irn)
246 for (i = 0, n = get_irn_arity(irn); i < n; ++i) {
247 ir_node *op = get_irn_n(irn, i);
250 || (arch_get_irn_flags(op) & arch_irn_flags_not_scheduled))
253 sum += compute_max_hops(env, op);
256 sum += get_result_hops_sum(env, irn);
261 static ir_node *reg_pressure_select(void *block_env, ir_nodeset_t *ready_set)
263 ir_nodeset_iterator_t iter;
264 reg_pressure_selector_env_t *env = (reg_pressure_selector_env_t*)block_env;
265 ir_node *irn, *res = NULL;
266 int curr_cost = INT_MAX;
268 assert(ir_nodeset_size(ready_set) > 0);
270 ir_nodeset_iterator_init(&iter, ready_set);
271 while ( (irn = ir_nodeset_iterator_next(&iter)) != NULL) {
273 Ignore branch instructions for the time being.
274 They should only be scheduled if there is nothing else.
277 int costs = reg_pr_costs(env, irn);
278 if (costs <= curr_cost) {
286 There was no result so we only saw a branch.
291 ir_nodeset_iterator_init(&iter, ready_set);
292 res = ir_nodeset_iterator_next(&iter);
294 assert(res && "There must be a node scheduled.");
297 ir_nodeset_insert(&env->already_scheduled, res);
301 static void sched_reg_pressure(ir_graph *irg)
303 static const list_sched_selector_t reg_pressure_selector = {
304 reg_pressure_graph_init,
305 reg_pressure_block_init,
307 NULL, /* node_ready */
308 NULL, /* node_selected */
309 reg_pressure_block_free,
312 be_list_sched_graph(irg, ®_pressure_selector);
315 BE_REGISTER_MODULE_CONSTRUCTOR(be_init_sched_regpress)
316 void be_init_sched_regpress(void)
318 be_register_scheduler("regpress", sched_reg_pressure);