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

   1 /**
   2  * Regpressure node selector.
   3  * Originally implemented by Sebastian Hack.
   4  * @author Christian Wuerdig
   5  * @date   29.08.2006
   6  * @cvs-id $Id$
   7  */
   8 #ifdef HAVE_CONFIG_H
   9 #include "config.h"
  10 #endif
  11
  12 #include <stdlib.h>
  13
  14 #include "iredges_t.h"
  15 #include "irgwalk.h"
  16
  17 #include "besched_t.h"
  18 #include "belistsched.h"
  19 #include "benode_t.h"
  20
  21
  22 typedef struct _usage_stats_t {
  23         ir_node *irn;
  24         struct _usage_stats_t *next;
  25         int max_hops;
  26         int uses_in_block;      /**< Number of uses inside the current block. */
  27         int already_consumed;   /**< Number of insns using this value already
  28                                                         scheduled. */
  29 } usage_stats_t;
  30
  31 typedef struct {
  32         const list_sched_selector_t *vtab;
  33         const arch_env_t *arch_env;
  34 } reg_pressure_main_env_t;
  35
  36 typedef struct {
  37         struct obstack obst;
  38         const reg_pressure_main_env_t *main_env;
  39         usage_stats_t *root;
  40         ir_nodeset_t already_scheduled;
  41 } reg_pressure_selector_env_t;
  42
  43
  44 #if 0
  45 /*
  46 * Ugly global variable for the compare function
  47 * since qsort(3) does not pass an extra pointer.
  48 */
  49 static ir_node *curr_bl = NULL;
  50
  51 static int cmp_usage(const void *a, const void *b)
  52 {
  53         struct trivial_sched_env *env;
  54         const ir_node *p = a;
  55         const ir_node *q = b;
  56         int res = 0;
  57
  58         res = is_live_end(env->curr_bl, a) - is_live_end(env->curr_bl, b);
  59
  60         /*
  61         * One of them is live at the end of the block.
  62         * Then, that one shall be scheduled at after the other
  63         */
  64         if(res != 0)
  65                 return res;
  66
  67
  68         return res;
  69 }
  70 #endif
  71
  72 static INLINE usage_stats_t *get_or_set_usage_stats(reg_pressure_selector_env_t *env, ir_node *irn)
  73 {
  74         usage_stats_t *us = get_irn_link(irn);
  75
  76         if(!us) {
  77                 us                   = obstack_alloc(&env->obst, sizeof(us[0]));
  78                 us->irn              = irn;
  79                 us->already_consumed = 0;
  80                 us->max_hops         = INT_MAX;
  81                 us->next             = env->root;
  82                 env->root            = us;
  83                 set_irn_link(irn, us);
  84         }
  85
  86         return us;
  87 }
  88
  89 static INLINE usage_stats_t *get_usage_stats(ir_node *irn)
  90 {
  91         usage_stats_t *us = get_irn_link(irn);
  92         assert(us && "This node must have usage stats");
  93         return us;
  94 }
  95
  96 static int max_hops_walker(reg_pressure_selector_env_t *env, ir_node *irn, ir_node *curr_bl, int depth, unsigned visited_nr)
  97 {
  98         ir_node *bl = get_nodes_block(irn);
  99         /*
 100         * If the reached node is not in the block desired,
 101         * return the value passed for this situation.
 102         */
 103         if(get_nodes_block(irn) != bl)
 104                 return block_dominates(bl, curr_bl) ? 0 : INT_MAX;
 105
 106         /*
 107         * If the node is in the current block but not
 108         * yet scheduled, we keep on searching from that node.
 109         */
 110         if(!ir_nodeset_contains(&env->already_scheduled, irn)) {
 111                 int i, n;
 112                 int res = 0;
 113                 for(i = 0, n = get_irn_ins_or_deps(irn); i < n; ++i) {
 114                         ir_node *operand = get_irn_in_or_dep(irn, i);
 115
 116                         if(get_irn_visited(operand) < visited_nr) {
 117                                 int tmp;
 118
 119                                 set_irn_visited(operand, visited_nr);
 120                                 tmp = max_hops_walker(env, operand, bl, depth + 1, visited_nr);
 121                                 res = MAX(tmp, res);
 122                         }
 123                 }
 124
 125                 return res;
 126         }
 127
 128         /*
 129         * If the node is in the current block and scheduled, return
 130         * the depth which indicates the number of steps to the
 131         * region of scheduled nodes.
 132         */
 133         return depth;
 134 }
 135
 136 static int compute_max_hops(reg_pressure_selector_env_t *env, ir_node *irn)
 137 {
 138         ir_node *bl   = get_nodes_block(irn);
 139         ir_graph *irg = get_irn_irg(bl);
 140         int res       = 0;
 141
 142         const ir_edge_t *edge;
 143
 144         foreach_out_edge(irn, edge) {
 145                 ir_node *user       = get_edge_src_irn(edge);
 146                 unsigned visited_nr = get_irg_visited(irg) + 1;
 147                 int max_hops;
 148
 149                 set_irg_visited(irg, visited_nr);
 150                 max_hops = max_hops_walker(env, user, irn, 0, visited_nr);
 151                 res      = MAX(res, max_hops);
 152         }
 153
 154         return res;
 155 }
 156
 157 static void *reg_pressure_graph_init(const list_sched_selector_t *vtab, const arch_env_t *arch_env, ir_graph *irg)
 158 {
 159         reg_pressure_main_env_t *main_env = xmalloc(sizeof(main_env[0]));
 160
 161         main_env->arch_env = arch_env;
 162         main_env->vtab     = vtab;
 163         irg_walk_graph(irg, firm_clear_link, NULL, NULL);
 164
 165         return main_env;
 166 }
 167
 168 static INLINE int must_appear_in_schedule(const list_sched_selector_t *sel, void *block_env, const ir_node *irn)
 169 {
 170         int res = -1;
 171
 172         if(sel->to_appear_in_schedule)
 173                 res = sel->to_appear_in_schedule(block_env, irn);
 174
 175         return res >= 0 ? res : (to_appear_in_schedule(irn) || be_is_Keep(irn) || be_is_CopyKeep(irn) || be_is_RegParams(irn));
 176 }
 177
 178 static void *reg_pressure_block_init(void *graph_env, ir_node *bl)
 179 {
 180         ir_node *irn;
 181         reg_pressure_selector_env_t *env  = xmalloc(sizeof(env[0]));
 182
 183         obstack_init(&env->obst);
 184         ir_nodeset_init(&env->already_scheduled);
 185         env->root              = NULL;
 186         env->main_env          = graph_env;
 187
 188         /*
 189         * Collect usage statistics.
 190         */
 191         sched_foreach(bl, irn) {
 192                 if(must_appear_in_schedule(env->main_env->vtab, env, irn)) {
 193                         int i, n;
 194
 195                         for(i = 0, n = get_irn_arity(irn); i < n; ++i) {
 196                                 //ir_node *op = get_irn_n(irn, i);
 197                                 if(must_appear_in_schedule(env->main_env->vtab, env, irn)) {
 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;
 202                                         else
 203 #endif
 204                                                 us->uses_in_block++;
 205                                 }
 206                         }
 207                 }
 208         }
 209
 210         return env;
 211 }
 212
 213 static void reg_pressure_block_free(void *block_env)
 214 {
 215         reg_pressure_selector_env_t *env = block_env;
 216         usage_stats_t *us;
 217
 218         for(us = env->root; us; us = us->next)
 219                 set_irn_link(us->irn, NULL);
 220
 221         obstack_free(&env->obst, NULL);
 222         ir_nodeset_destroy(&env->already_scheduled);
 223         free(env);
 224 }
 225
 226 static int get_result_hops_sum(reg_pressure_selector_env_t *env, ir_node *irn)
 227 {
 228         int res = 0;
 229         if(get_irn_mode(irn) == mode_T) {
 230                 const ir_edge_t *edge;
 231
 232                 foreach_out_edge(irn, edge)
 233                         res += get_result_hops_sum(env, get_edge_src_irn(edge));
 234         }
 235
 236         else if(mode_is_data(get_irn_mode(irn)))
 237                 res = compute_max_hops(env, irn);
 238
 239
 240         return res;
 241 }
 242
 243 static INLINE int reg_pr_costs(reg_pressure_selector_env_t *env, ir_node *irn)
 244 {
 245         int i, n;
 246         int sum = 0;
 247
 248         for(i = 0, n = get_irn_arity(irn); i < n; ++i) {
 249                 ir_node *op = get_irn_n(irn, i);
 250
 251                 if(must_appear_in_schedule(env->main_env->vtab, env, op))
 252                         sum += compute_max_hops(env, op);
 253         }
 254
 255         sum += get_result_hops_sum(env, irn);
 256
 257         return sum;
 258 }
 259
 260 static ir_node *reg_pressure_select(void *block_env, ir_nodeset_t *ready_set,
 261                                     ir_nodeset_t *live_set)
 262 {
 263         ir_nodeset_iterator_t iter;
 264         reg_pressure_selector_env_t *env = block_env;
 265         ir_node *irn, *res     = NULL;
 266         int curr_cost          = INT_MAX;
 267
 268         assert(ir_nodeset_size(ready_set) > 0);
 269
 270         ir_nodeset_iterator_init(&iter, ready_set);
 271         while( (irn = ir_nodeset_iterator_next(&iter)) != NULL) {
 272                 /*
 273                 Ignore branch instructions for the time being.
 274                 They should only be scheduled if there is nothing else.
 275                 */
 276                 if (! arch_irn_class_is(env->main_env->arch_env, irn, branch)) {
 277                         int costs = reg_pr_costs(env, irn);
 278                         if (costs <= curr_cost) {
 279                                 res       = irn;
 280                                 curr_cost = costs;
 281                         }
 282                 }
 283         }
 284
 285         /*
 286         There was no result so we only saw a branch.
 287         Take it and finish.
 288         */
 289
 290         if(!res) {
 291                 ir_nodeset_iterator_init(&iter, ready_set);
 292                 res = ir_nodeset_iterator_next(&iter);
 293
 294                 assert(res && "There must be a node scheduled.");
 295         }
 296
 297         ir_nodeset_insert(&env->already_scheduled, res);
 298         return res;
 299 }
 300
 301 static const list_sched_selector_t reg_pressure_selector_struct = {
 302         reg_pressure_graph_init,
 303         reg_pressure_block_init,
 304         reg_pressure_select,
 305         NULL,                    /* to_appear_in_schedule */
 306         NULL,                    /* node_ready */
 307         NULL,                    /* node_selected */
 308         NULL,                    /* exectime */
 309         NULL,                    /* latency */
 310         reg_pressure_block_free,
 311         free
 312 };
 313
 314 const list_sched_selector_t *reg_pressure_selector = &reg_pressure_selector_struct;