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 #ifdef HAVE_CONFIG_H
  28 #include "config.h"
  29 #endif
  30
  31 #include <stdlib.h>
  32
  33 #include "iredges_t.h"
  34 #include "irgwalk.h"
  35 #include "irtools.h"
  36
  37 #include "besched_t.h"
  38 #include "belistsched.h"
  39 #include "benode_t.h"
  40
  41
  42 typedef struct _usage_stats_t {
  43         ir_node *irn;
  44         struct _usage_stats_t *next;
  45         int max_hops;
  46         int uses_in_block;      /**< Number of uses inside the current block. */
  47         int already_consumed;   /**< Number of insns using this value already
  48                                                         scheduled. */
  49 } usage_stats_t;
  50
  51 typedef struct {
  52         const list_sched_selector_t *vtab;
  53         const arch_env_t *arch_env;
  54 } reg_pressure_main_env_t;
  55
  56 typedef struct {
  57         struct obstack obst;
  58         const reg_pressure_main_env_t *main_env;
  59         usage_stats_t *root;
  60         ir_nodeset_t already_scheduled;
  61 } reg_pressure_selector_env_t;
  62
  63
  64 #if 0
  65 /*
  66 * Ugly global variable for the compare function
  67 * since qsort(3) does not pass an extra pointer.
  68 */
  69 static ir_node *curr_bl = NULL;
  70
  71 static int cmp_usage(const void *a, const void *b)
  72 {
  73         struct trivial_sched_env *env;
  74         const ir_node *p = a;
  75         const ir_node *q = b;
  76         int res = 0;
  77
  78         res = is_live_end(env->curr_bl, a) - is_live_end(env->curr_bl, b);
  79
  80         /*
  81         * One of them is live at the end of the block.
  82         * Then, that one shall be scheduled at after the other
  83         */
  84         if(res != 0)
  85                 return res;
  86
  87
  88         return res;
  89 }
  90 #endif
  91
  92 static INLINE usage_stats_t *get_or_set_usage_stats(reg_pressure_selector_env_t *env, ir_node *irn)
  93 {
  94         usage_stats_t *us = get_irn_link(irn);
  95
  96         if(!us) {
  97                 us                   = obstack_alloc(&env->obst, sizeof(us[0]));
  98                 us->irn              = irn;
  99                 us->already_consumed = 0;
 100                 us->max_hops         = INT_MAX;
 101                 us->next             = env->root;
 102                 env->root            = us;
 103                 set_irn_link(irn, us);
 104         }
 105
 106         return us;
 107 }
 108
 109 static INLINE usage_stats_t *get_usage_stats(ir_node *irn)
 110 {
 111         usage_stats_t *us = get_irn_link(irn);
 112         assert(us && "This node must have usage stats");
 113         return us;
 114 }
 115
 116 static int max_hops_walker(reg_pressure_selector_env_t *env, ir_node *irn, ir_node *curr_bl, int depth, unsigned visited_nr)
 117 {
 118         ir_node *bl = get_nodes_block(irn);
 119         /*
 120         * If the reached node is not in the block desired,
 121         * return the value passed for this situation.
 122         */
 123         if(get_nodes_block(irn) != bl)
 124                 return block_dominates(bl, curr_bl) ? 0 : INT_MAX;
 125
 126         /*
 127         * If the node is in the current block but not
 128         * yet scheduled, we keep on searching from that node.
 129         */
 130         if(!ir_nodeset_contains(&env->already_scheduled, irn)) {
 131                 int i, n;
 132                 int res = 0;
 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);
 135
 136                         if(get_irn_visited(operand) < visited_nr) {
 137                                 int tmp;
 138
 139                                 set_irn_visited(operand, visited_nr);
 140                                 tmp = max_hops_walker(env, operand, bl, depth + 1, visited_nr);
 141                                 res = MAX(tmp, res);
 142                         }
 143                 }
 144
 145                 return res;
 146         }
 147
 148         /*
 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.
 152         */
 153         return depth;
 154 }
 155
 156 static int compute_max_hops(reg_pressure_selector_env_t *env, ir_node *irn)
 157 {
 158         ir_node *bl   = get_nodes_block(irn);
 159         ir_graph *irg = get_irn_irg(bl);
 160         int res       = 0;
 161
 162         const ir_edge_t *edge;
 163
 164         foreach_out_edge(irn, edge) {
 165                 ir_node *user       = get_edge_src_irn(edge);
 166                 unsigned visited_nr = get_irg_visited(irg) + 1;
 167                 int max_hops;
 168
 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);
 172         }
 173
 174         return res;
 175 }
 176
 177 static void *reg_pressure_graph_init(const list_sched_selector_t *vtab, const be_irg_t *birg)
 178 {
 179         reg_pressure_main_env_t *main_env = xmalloc(sizeof(main_env[0]));
 180
 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);
 184
 185         return main_env;
 186 }
 187
 188 static INLINE int must_appear_in_schedule(const list_sched_selector_t *sel, void *block_env, const ir_node *irn)
 189 {
 190         int res = -1;
 191
 192         if(sel->to_appear_in_schedule)
 193                 res = sel->to_appear_in_schedule(block_env, irn);
 194
 195         return res >= 0 ? res : (to_appear_in_schedule(irn) || be_is_Keep(irn) || be_is_CopyKeep(irn) || be_is_RegParams(irn));
 196 }
 197
 198 static void *reg_pressure_block_init(void *graph_env, ir_node *bl)
 199 {
 200         ir_node *irn;
 201         reg_pressure_selector_env_t *env  = xmalloc(sizeof(env[0]));
 202
 203         obstack_init(&env->obst);
 204         ir_nodeset_init(&env->already_scheduled);
 205         env->root              = NULL;
 206         env->main_env          = graph_env;
 207
 208         /*
 209         * Collect usage statistics.
 210         */
 211         sched_foreach(bl, irn) {
 212                 if(must_appear_in_schedule(env->main_env->vtab, env, irn)) {
 213                         int i, n;
 214
 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;
 222                                         else
 223 #endif
 224                                                 us->uses_in_block++;
 225                                 }
 226                         }
 227                 }
 228         }
 229
 230         return env;
 231 }
 232
 233 static void reg_pressure_block_free(void *block_env)
 234 {
 235         reg_pressure_selector_env_t *env = block_env;
 236         usage_stats_t *us;
 237
 238         for(us = env->root; us; us = us->next)
 239                 set_irn_link(us->irn, NULL);
 240
 241         obstack_free(&env->obst, NULL);
 242         ir_nodeset_destroy(&env->already_scheduled);
 243         free(env);
 244 }
 245
 246 static int get_result_hops_sum(reg_pressure_selector_env_t *env, ir_node *irn)
 247 {
 248         int res = 0;
 249         if(get_irn_mode(irn) == mode_T) {
 250                 const ir_edge_t *edge;
 251
 252                 foreach_out_edge(irn, edge)
 253                         res += get_result_hops_sum(env, get_edge_src_irn(edge));
 254         }
 255
 256         else if(mode_is_data(get_irn_mode(irn)))
 257                 res = compute_max_hops(env, irn);
 258
 259
 260         return res;
 261 }
 262
 263 static INLINE int reg_pr_costs(reg_pressure_selector_env_t *env, ir_node *irn)
 264 {
 265         int i, n;
 266         int sum = 0;
 267
 268         for(i = 0, n = get_irn_arity(irn); i < n; ++i) {
 269                 ir_node *op = get_irn_n(irn, i);
 270
 271                 if(must_appear_in_schedule(env->main_env->vtab, env, op))
 272                         sum += compute_max_hops(env, op);
 273         }
 274
 275         sum += get_result_hops_sum(env, irn);
 276
 277         return sum;
 278 }
 279
 280 static ir_node *reg_pressure_select(void *block_env, ir_nodeset_t *ready_set,
 281                                     ir_nodeset_t *live_set)
 282 {
 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;
 287         (void) live_set;
 288
 289         assert(ir_nodeset_size(ready_set) > 0);
 290
 291         ir_nodeset_iterator_init(&iter, ready_set);
 292         while( (irn = ir_nodeset_iterator_next(&iter)) != NULL) {
 293                 /*
 294                 Ignore branch instructions for the time being.
 295                 They should only be scheduled if there is nothing else.
 296                 */
 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) {
 300                                 res       = irn;
 301                                 curr_cost = costs;
 302                         }
 303                 }
 304         }
 305
 306         /*
 307         There was no result so we only saw a branch.
 308         Take it and finish.
 309         */
 310
 311         if(!res) {
 312                 ir_nodeset_iterator_init(&iter, ready_set);
 313                 res = ir_nodeset_iterator_next(&iter);
 314
 315                 assert(res && "There must be a node scheduled.");
 316         }
 317
 318         ir_nodeset_insert(&env->already_scheduled, res);
 319         return res;
 320 }
 321
 322 const list_sched_selector_t reg_pressure_selector = {
 323         reg_pressure_graph_init,
 324         reg_pressure_block_init,
 325         reg_pressure_select,
 326         NULL,                    /* to_appear_in_schedule */
 327         NULL,                    /* node_ready */
 328         NULL,                    /* node_selected */
 329         NULL,                    /* exectime */
 330         NULL,                    /* latency */
 331         reg_pressure_block_free,
 332         free
 333 };