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
33 #include "iredges_t.h"
37 #include "besched_t.h"
38 #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
52 const list_sched_selector_t *vtab;
53 const arch_env_t *arch_env;
54 } reg_pressure_main_env_t;
58 const reg_pressure_main_env_t *main_env;
60 ir_nodeset_t already_scheduled;
61 } reg_pressure_selector_env_t;
66 * Ugly global variable for the compare function
67 * since qsort(3) does not pass an extra pointer.
69 static ir_node *curr_bl = NULL;
71 static int cmp_usage(const void *a, const void *b)
73 struct trivial_sched_env *env;
78 res = is_live_end(env->curr_bl, a) - is_live_end(env->curr_bl, b);
81 * One of them is live at the end of the block.
82 * Then, that one shall be scheduled at after the other
92 static INLINE usage_stats_t *get_or_set_usage_stats(reg_pressure_selector_env_t *env, ir_node *irn)
94 usage_stats_t *us = get_irn_link(irn);
97 us = obstack_alloc(&env->obst, sizeof(us[0]));
99 us->already_consumed = 0;
100 us->max_hops = INT_MAX;
101 us->next = env->root;
103 set_irn_link(irn, us);
109 static INLINE usage_stats_t *get_usage_stats(ir_node *irn)
111 usage_stats_t *us = get_irn_link(irn);
112 assert(us && "This node must have usage stats");
116 static int max_hops_walker(reg_pressure_selector_env_t *env, ir_node *irn, ir_node *curr_bl, int depth, unsigned visited_nr)
118 ir_node *bl = get_nodes_block(irn);
120 * If the reached node is not in the block desired,
121 * return the value passed for this situation.
123 if(get_nodes_block(irn) != bl)
124 return block_dominates(bl, curr_bl) ? 0 : INT_MAX;
127 * If the node is in the current block but not
128 * yet scheduled, we keep on searching from that node.
130 if(!ir_nodeset_contains(&env->already_scheduled, irn)) {
133 for(i = 0, n = get_irn_ins_or_deps(irn); i < n; ++i) {
134 ir_node *operand = get_irn_in_or_dep(irn, i);
136 if(get_irn_visited(operand) < visited_nr) {
139 set_irn_visited(operand, visited_nr);
140 tmp = max_hops_walker(env, operand, bl, depth + 1, visited_nr);
149 * If the node is in the current block and scheduled, return
150 * the depth which indicates the number of steps to the
151 * region of scheduled nodes.
156 static int compute_max_hops(reg_pressure_selector_env_t *env, ir_node *irn)
158 ir_node *bl = get_nodes_block(irn);
159 ir_graph *irg = get_irn_irg(bl);
162 const ir_edge_t *edge;
164 foreach_out_edge(irn, edge) {
165 ir_node *user = get_edge_src_irn(edge);
166 unsigned visited_nr = get_irg_visited(irg) + 1;
169 set_irg_visited(irg, visited_nr);
170 max_hops = max_hops_walker(env, user, irn, 0, visited_nr);
171 res = MAX(res, max_hops);
177 static void *reg_pressure_graph_init(const list_sched_selector_t *vtab, const be_irg_t *birg)
179 reg_pressure_main_env_t *main_env = xmalloc(sizeof(main_env[0]));
181 main_env->arch_env = be_get_birg_arch_env(birg);
182 main_env->vtab = vtab;
183 irg_walk_graph(be_get_birg_irg(birg), firm_clear_link, NULL, NULL);
188 static INLINE int must_appear_in_schedule(const list_sched_selector_t *sel, void *block_env, const ir_node *irn)
192 if(sel->to_appear_in_schedule)
193 res = sel->to_appear_in_schedule(block_env, irn);
195 return res >= 0 ? res : (to_appear_in_schedule(irn) || be_is_Keep(irn) || be_is_CopyKeep(irn) || be_is_RegParams(irn));
198 static void *reg_pressure_block_init(void *graph_env, ir_node *bl)
201 reg_pressure_selector_env_t *env = xmalloc(sizeof(env[0]));
203 obstack_init(&env->obst);
204 ir_nodeset_init(&env->already_scheduled);
206 env->main_env = graph_env;
209 * Collect usage statistics.
211 sched_foreach(bl, irn) {
212 if(must_appear_in_schedule(env->main_env->vtab, env, irn)) {
215 for(i = 0, n = get_irn_arity(irn); i < n; ++i) {
216 //ir_node *op = get_irn_n(irn, i);
217 if(must_appear_in_schedule(env->main_env->vtab, env, irn)) {
218 usage_stats_t *us = get_or_set_usage_stats(env, irn);
219 #if 0 /* Liveness is not computed here! */
220 if(is_live_end(bl, op))
221 us->uses_in_block = 99999;
233 static void reg_pressure_block_free(void *block_env)
235 reg_pressure_selector_env_t *env = block_env;
238 for(us = env->root; us; us = us->next)
239 set_irn_link(us->irn, NULL);
241 obstack_free(&env->obst, NULL);
242 ir_nodeset_destroy(&env->already_scheduled);
246 static int get_result_hops_sum(reg_pressure_selector_env_t *env, ir_node *irn)
249 if(get_irn_mode(irn) == mode_T) {
250 const ir_edge_t *edge;
252 foreach_out_edge(irn, edge)
253 res += get_result_hops_sum(env, get_edge_src_irn(edge));
256 else if(mode_is_data(get_irn_mode(irn)))
257 res = compute_max_hops(env, irn);
263 static INLINE int reg_pr_costs(reg_pressure_selector_env_t *env, ir_node *irn)
268 for(i = 0, n = get_irn_arity(irn); i < n; ++i) {
269 ir_node *op = get_irn_n(irn, i);
271 if(must_appear_in_schedule(env->main_env->vtab, env, op))
272 sum += compute_max_hops(env, op);
275 sum += get_result_hops_sum(env, irn);
280 static ir_node *reg_pressure_select(void *block_env, ir_nodeset_t *ready_set,
281 ir_nodeset_t *live_set)
283 ir_nodeset_iterator_t iter;
284 reg_pressure_selector_env_t *env = block_env;
285 ir_node *irn, *res = NULL;
286 int curr_cost = INT_MAX;
289 assert(ir_nodeset_size(ready_set) > 0);
291 ir_nodeset_iterator_init(&iter, ready_set);
292 while( (irn = ir_nodeset_iterator_next(&iter)) != NULL) {
294 Ignore branch instructions for the time being.
295 They should only be scheduled if there is nothing else.
297 if (! arch_irn_class_is(env->main_env->arch_env, irn, branch)) {
298 int costs = reg_pr_costs(env, irn);
299 if (costs <= curr_cost) {
307 There was no result so we only saw a branch.
312 ir_nodeset_iterator_init(&iter, ready_set);
313 res = ir_nodeset_iterator_next(&iter);
315 assert(res && "There must be a node scheduled.");
318 ir_nodeset_insert(&env->already_scheduled, res);
322 const list_sched_selector_t reg_pressure_selector = {
323 reg_pressure_graph_init,
324 reg_pressure_block_init,
326 NULL, /* to_appear_in_schedule */
327 NULL, /* node_ready */
328 NULL, /* node_selected */
331 reg_pressure_block_free,