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"
35 #include "besched_t.h"
36 #include "belistsched.h"
40 typedef struct _usage_stats_t {
42 struct _usage_stats_t *next;
44 int uses_in_block; /**< Number of uses inside the current block. */
45 int already_consumed; /**< Number of insns using this value already
50 const list_sched_selector_t *vtab;
51 } reg_pressure_main_env_t;
55 const reg_pressure_main_env_t *main_env;
57 ir_nodeset_t already_scheduled;
58 } reg_pressure_selector_env_t;
63 * Ugly global variable for the compare function
64 * since qsort(3) does not pass an extra pointer.
66 static ir_node *curr_bl = NULL;
68 static int cmp_usage(const void *a, const void *b)
70 struct trivial_sched_env *env;
75 res = is_live_end(env->curr_bl, a) - is_live_end(env->curr_bl, b);
78 * One of them is live at the end of the block.
79 * Then, that one shall be scheduled at after the other
89 static INLINE usage_stats_t *get_or_set_usage_stats(reg_pressure_selector_env_t *env, ir_node *irn)
91 usage_stats_t *us = get_irn_link(irn);
94 us = obstack_alloc(&env->obst, sizeof(us[0]));
96 us->already_consumed = 0;
97 us->max_hops = INT_MAX;
100 set_irn_link(irn, us);
106 static INLINE usage_stats_t *get_usage_stats(ir_node *irn)
108 usage_stats_t *us = get_irn_link(irn);
109 assert(us && "This node must have usage stats");
113 static int max_hops_walker(reg_pressure_selector_env_t *env, ir_node *irn, ir_node *curr_bl, int depth, unsigned visited_nr)
115 ir_node *bl = get_nodes_block(irn);
117 * If the reached node is not in the block desired,
118 * return the value passed for this situation.
120 if(get_nodes_block(irn) != bl)
121 return block_dominates(bl, curr_bl) ? 0 : INT_MAX;
124 * If the node is in the current block but not
125 * yet scheduled, we keep on searching from that node.
127 if(!ir_nodeset_contains(&env->already_scheduled, irn)) {
130 for(i = 0, n = get_irn_ins_or_deps(irn); i < n; ++i) {
131 ir_node *operand = get_irn_in_or_dep(irn, i);
133 if(get_irn_visited(operand) < visited_nr) {
136 set_irn_visited(operand, visited_nr);
137 tmp = max_hops_walker(env, operand, bl, depth + 1, visited_nr);
146 * If the node is in the current block and scheduled, return
147 * the depth which indicates the number of steps to the
148 * region of scheduled nodes.
153 static int compute_max_hops(reg_pressure_selector_env_t *env, ir_node *irn)
155 ir_node *bl = get_nodes_block(irn);
156 ir_graph *irg = get_irn_irg(bl);
159 const ir_edge_t *edge;
161 foreach_out_edge(irn, edge) {
162 ir_node *user = get_edge_src_irn(edge);
163 unsigned visited_nr = get_irg_visited(irg) + 1;
166 set_irg_visited(irg, visited_nr);
167 max_hops = max_hops_walker(env, user, irn, 0, visited_nr);
168 res = MAX(res, max_hops);
174 static void *reg_pressure_graph_init(const list_sched_selector_t *vtab, const be_irg_t *birg)
176 reg_pressure_main_env_t *main_env = XMALLOC(reg_pressure_main_env_t);
178 main_env->vtab = vtab;
179 irg_walk_graph(be_get_birg_irg(birg), firm_clear_link, NULL, NULL);
184 static INLINE int must_appear_in_schedule(const list_sched_selector_t *sel, void *block_env, const ir_node *irn)
188 if(sel->to_appear_in_schedule)
189 res = sel->to_appear_in_schedule(block_env, irn);
191 return res >= 0 ? res : (to_appear_in_schedule(irn) || be_is_Keep(irn) || be_is_CopyKeep(irn) || be_is_RegParams(irn));
194 static void *reg_pressure_block_init(void *graph_env, ir_node *bl)
197 reg_pressure_selector_env_t *env = XMALLOC(reg_pressure_selector_env_t);
199 obstack_init(&env->obst);
200 ir_nodeset_init(&env->already_scheduled);
202 env->main_env = graph_env;
205 * Collect usage statistics.
207 sched_foreach(bl, irn) {
208 if(must_appear_in_schedule(env->main_env->vtab, env, irn)) {
211 for(i = 0, n = get_irn_arity(irn); i < n; ++i) {
212 //ir_node *op = get_irn_n(irn, i);
213 if(must_appear_in_schedule(env->main_env->vtab, env, irn)) {
214 usage_stats_t *us = get_or_set_usage_stats(env, irn);
215 #if 0 /* Liveness is not computed here! */
216 if(is_live_end(bl, op))
217 us->uses_in_block = 99999;
229 static void reg_pressure_block_free(void *block_env)
231 reg_pressure_selector_env_t *env = block_env;
234 for(us = env->root; us; us = us->next)
235 set_irn_link(us->irn, NULL);
237 obstack_free(&env->obst, NULL);
238 ir_nodeset_destroy(&env->already_scheduled);
242 static int get_result_hops_sum(reg_pressure_selector_env_t *env, ir_node *irn)
245 if(get_irn_mode(irn) == mode_T) {
246 const ir_edge_t *edge;
248 foreach_out_edge(irn, edge)
249 res += get_result_hops_sum(env, get_edge_src_irn(edge));
252 else if(mode_is_data(get_irn_mode(irn)))
253 res = compute_max_hops(env, irn);
259 static INLINE int reg_pr_costs(reg_pressure_selector_env_t *env, ir_node *irn)
264 for(i = 0, n = get_irn_arity(irn); i < n; ++i) {
265 ir_node *op = get_irn_n(irn, i);
267 if(must_appear_in_schedule(env->main_env->vtab, env, op))
268 sum += compute_max_hops(env, op);
271 sum += get_result_hops_sum(env, irn);
276 static ir_node *reg_pressure_select(void *block_env, ir_nodeset_t *ready_set,
277 ir_nodeset_t *live_set)
279 ir_nodeset_iterator_t iter;
280 reg_pressure_selector_env_t *env = block_env;
281 ir_node *irn, *res = NULL;
282 int curr_cost = INT_MAX;
285 assert(ir_nodeset_size(ready_set) > 0);
287 ir_nodeset_iterator_init(&iter, ready_set);
288 while( (irn = ir_nodeset_iterator_next(&iter)) != NULL) {
290 Ignore branch instructions for the time being.
291 They should only be scheduled if there is nothing else.
293 if (!arch_irn_class_is(irn, branch)) {
294 int costs = reg_pr_costs(env, irn);
295 if (costs <= curr_cost) {
303 There was no result so we only saw a branch.
308 ir_nodeset_iterator_init(&iter, ready_set);
309 res = ir_nodeset_iterator_next(&iter);
311 assert(res && "There must be a node scheduled.");
314 ir_nodeset_insert(&env->already_scheduled, res);
318 const list_sched_selector_t reg_pressure_selector = {
319 reg_pressure_graph_init,
320 reg_pressure_block_init,
322 NULL, /* to_appear_in_schedule */
323 NULL, /* node_ready */
324 NULL, /* node_selected */
327 reg_pressure_block_free,