nsz Git - libfirm/blob - ir/be/beschedregpress.c

   1 /*
   2  * Copyright (C) 1995-2008 University of Karlsruhe.  All right reserved.
   3  *
   4  * This file is part of libFirm.
   5  *
   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.
  10  *
  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.
  14  *
  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
  17  * PURPOSE.
  18  */
  19
  20 /**
  21  * @file
  22  * @brief       Register pressure node selector.
  23  * @author      Sebastian Hack
  24  * @date        29.08.2006
  25  * @version     $Id$
  26  */
  27 #include "config.h"
  28
  29 #include <stdlib.h>
  30
  31 #include "iredges_t.h"
  32 #include "irgwalk.h"
  33 #include "irtools.h"
  34
  35 #include "besched.h"
  36 #include "belistsched.h"
  37 #include "benode.h"
  38
  39
  40 typedef struct usage_stats_t {
  41         ir_node *irn;
  42         struct usage_stats_t *next;
  43         int max_hops;
  44         int uses_in_block;      /**< Number of uses inside the current block. */
  45         int already_consumed;   /**< Number of insns using this value already
  46                                                         scheduled. */
  47 } usage_stats_t;
  48
  49 typedef struct {
  50         const list_sched_selector_t *vtab;
  51 } reg_pressure_main_env_t;
  52
  53 typedef struct {
  54         struct obstack obst;
  55         const reg_pressure_main_env_t *main_env;
  56         usage_stats_t *root;
  57         ir_nodeset_t already_scheduled;
  58 } reg_pressure_selector_env_t;
  59
  60
  61 #if 0
  62 /*
  63 * Ugly global variable for the compare function
  64 * since qsort(3) does not pass an extra pointer.
  65 */
  66 static ir_node *curr_bl = NULL;
  67
  68 static int cmp_usage(const void *a, const void *b)
  69 {
  70         struct trivial_sched_env *env;
  71         const ir_node *p = a;
  72         const ir_node *q = b;
  73         int res = 0;
  74
  75         res = is_live_end(env->curr_bl, a) - is_live_end(env->curr_bl, b);
  76
  77         /*
  78         * One of them is live at the end of the block.
  79         * Then, that one shall be scheduled at after the other
  80         */
  81         if (res != 0)
  82                 return res;
  83
  84
  85         return res;
  86 }
  87 #endif
  88
  89 static inline usage_stats_t *get_or_set_usage_stats(reg_pressure_selector_env_t *env, ir_node *irn)
  90 {
  91         usage_stats_t *us = get_irn_link(irn);
  92
  93         if (!us) {
  94                 us                   = OALLOC(&env->obst, usage_stats_t);
  95                 us->irn              = irn;
  96                 us->already_consumed = 0;
  97                 us->max_hops         = INT_MAX;
  98                 us->next             = env->root;
  99                 env->root            = us;
 100                 set_irn_link(irn, us);
 101         }
 102
 103         return us;
 104 }
 105
 106 static inline usage_stats_t *get_usage_stats(ir_node *irn)
 107 {
 108         usage_stats_t *us = get_irn_link(irn);
 109         assert(us && "This node must have usage stats");
 110         return us;
 111 }
 112
 113 static int max_hops_walker(reg_pressure_selector_env_t *env, ir_node *irn, ir_node *curr_bl, int depth, unsigned visited_nr)
 114 {
 115         ir_node *bl = get_nodes_block(irn);
 116         /*
 117         * If the reached node is not in the block desired,
 118         * return the value passed for this situation.
 119         */
 120         if (get_nodes_block(irn) != bl)
 121                 return block_dominates(bl, curr_bl) ? 0 : INT_MAX;
 122
 123         /*
 124         * If the node is in the current block but not
 125         * yet scheduled, we keep on searching from that node.
 126         */
 127         if (!ir_nodeset_contains(&env->already_scheduled, irn)) {
 128                 int i, n;
 129                 int res = 0;
 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);
 132
 133                         if (get_irn_visited(operand) < visited_nr) {
 134                                 int tmp;
 135
 136                                 set_irn_visited(operand, visited_nr);
 137                                 tmp = max_hops_walker(env, operand, bl, depth + 1, visited_nr);
 138                                 res = MAX(tmp, res);
 139                         }
 140                 }
 141
 142                 return res;
 143         }
 144
 145         /*
 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.
 149         */
 150         return depth;
 151 }
 152
 153 static int compute_max_hops(reg_pressure_selector_env_t *env, ir_node *irn)
 154 {
 155         ir_node *bl   = get_nodes_block(irn);
 156         ir_graph *irg = get_irn_irg(bl);
 157         int res       = 0;
 158
 159         const ir_edge_t *edge;
 160
 161         foreach_out_edge(irn, edge) {
 162                 ir_node *user       = get_edge_src_irn(edge);
 163                 unsigned visited_nr = get_irg_visited(irg) + 1;
 164                 int max_hops;
 165
 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);
 169         }
 170
 171         return res;
 172 }
 173
 174 static void *reg_pressure_graph_init(const list_sched_selector_t *vtab, ir_graph *irg)
 175 {
 176         reg_pressure_main_env_t *main_env = XMALLOC(reg_pressure_main_env_t);
 177
 178         main_env->vtab = vtab;
 179         irg_walk_graph(irg, firm_clear_link, NULL, NULL);
 180
 181         return main_env;
 182 }
 183
 184 static void *reg_pressure_block_init(void *graph_env, ir_node *bl)
 185 {
 186         ir_node *irn;
 187         reg_pressure_selector_env_t *env = XMALLOC(reg_pressure_selector_env_t);
 188
 189         obstack_init(&env->obst);
 190         ir_nodeset_init(&env->already_scheduled);
 191         env->root              = NULL;
 192         env->main_env          = graph_env;
 193
 194         /*
 195         * Collect usage statistics.
 196         */
 197         sched_foreach(bl, irn) {
 198                 if (to_appear_in_schedule(irn)) {
 199                         int i, n;
 200
 201                         for (i = 0, n = get_irn_arity(irn); i < n; ++i) {
 202                                 //ir_node *op = get_irn_n(irn, i);
 203                                 if (to_appear_in_schedule(irn)) {
 204                                         usage_stats_t *us = get_or_set_usage_stats(env, irn);
 205 #if 0 /* Liveness is not computed here! */
 206                                         if (is_live_end(bl, op))
 207                                                 us->uses_in_block = 99999;
 208                                         else
 209 #endif
 210                                                 us->uses_in_block++;
 211                                 }
 212                         }
 213                 }
 214         }
 215
 216         return env;
 217 }
 218
 219 static void reg_pressure_block_free(void *block_env)
 220 {
 221         reg_pressure_selector_env_t *env = block_env;
 222         usage_stats_t *us;
 223
 224         for (us = env->root; us; us = us->next)
 225                 set_irn_link(us->irn, NULL);
 226
 227         obstack_free(&env->obst, NULL);
 228         ir_nodeset_destroy(&env->already_scheduled);
 229         free(env);
 230 }
 231
 232 static int get_result_hops_sum(reg_pressure_selector_env_t *env, ir_node *irn)
 233 {
 234         int res = 0;
 235         if (get_irn_mode(irn) == mode_T) {
 236                 const ir_edge_t *edge;
 237
 238                 foreach_out_edge(irn, edge)
 239                         res += get_result_hops_sum(env, get_edge_src_irn(edge));
 240         }
 241
 242         else if (mode_is_data(get_irn_mode(irn)))
 243                 res = compute_max_hops(env, irn);
 244
 245
 246         return res;
 247 }
 248
 249 static inline int reg_pr_costs(reg_pressure_selector_env_t *env, ir_node *irn)
 250 {
 251         int i, n;
 252         int sum = 0;
 253
 254         for (i = 0, n = get_irn_arity(irn); i < n; ++i) {
 255                 ir_node *op = get_irn_n(irn, i);
 256
 257                 if (to_appear_in_schedule(op))
 258                         sum += compute_max_hops(env, op);
 259         }
 260
 261         sum += get_result_hops_sum(env, irn);
 262
 263         return sum;
 264 }
 265
 266 static ir_node *reg_pressure_select(void *block_env, ir_nodeset_t *ready_set,
 267                                     ir_nodeset_t *live_set)
 268 {
 269         ir_nodeset_iterator_t iter;
 270         reg_pressure_selector_env_t *env = block_env;
 271         ir_node *irn, *res     = NULL;
 272         int curr_cost          = INT_MAX;
 273         (void) live_set;
 274
 275         assert(ir_nodeset_size(ready_set) > 0);
 276
 277         ir_nodeset_iterator_init(&iter, ready_set);
 278         while ( (irn = ir_nodeset_iterator_next(&iter)) != NULL) {
 279                 /*
 280                 Ignore branch instructions for the time being.
 281                 They should only be scheduled if there is nothing else.
 282                 */
 283                 if (!is_cfop(irn)) {
 284                         int costs = reg_pr_costs(env, irn);
 285                         if (costs <= curr_cost) {
 286                                 res       = irn;
 287                                 curr_cost = costs;
 288                         }
 289                 }
 290         }
 291
 292         /*
 293         There was no result so we only saw a branch.
 294         Take it and finish.
 295         */
 296
 297         if (!res) {
 298                 ir_nodeset_iterator_init(&iter, ready_set);
 299                 res = ir_nodeset_iterator_next(&iter);
 300
 301                 assert(res && "There must be a node scheduled.");
 302         }
 303
 304         ir_nodeset_insert(&env->already_scheduled, res);
 305         return res;
 306 }
 307
 308 const list_sched_selector_t reg_pressure_selector = {
 309         reg_pressure_graph_init,
 310         reg_pressure_block_init,
 311         reg_pressure_select,
 312         NULL,                    /* node_ready */
 313         NULL,                    /* node_selected */
 314         NULL,                    /* exectime */
 315         NULL,                    /* latency */
 316         reg_pressure_block_free,
 317         free
 318 };