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

   1 /*
   2  * Copyright (C) 1995-2007 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       Methods to compute when a value will be used again.
  23  * @author      Sebastian Hack, Matthias Braun
  24  * @date        27.06.2005
  25  * @version     $Id$
  26  */
  27 #ifdef HAVE_CONFIG_H
  28 #include "config.h"
  29 #endif
  30
  31 #include <limits.h>
  32 #include <stdlib.h>
  33
  34 #include "config.h"
  35 #include "obst.h"
  36 #include "pmap.h"
  37 #include "debug.h"
  38
  39 #include "irgwalk.h"
  40 #include "irnode_t.h"
  41 #include "ircons_t.h"
  42 #include "irgraph_t.h"
  43 #include "iredges_t.h"
  44 #include "irdom_t.h"
  45
  46 #include "be_t.h"
  47 #include "beutil.h"
  48 #include "belive_t.h"
  49 #include "benode_t.h"
  50 #include "besched_t.h"
  51 #include "beirgmod.h"
  52 #include "bearch_t.h"
  53 #include "beuses.h"
  54 #include "benodesets.h"
  55
  56 #define SCAN_INTERBLOCK_USES
  57
  58 typedef struct _be_use_t {
  59         const ir_node *block;
  60         const ir_node *node;
  61         int outermost_loop;
  62         unsigned next_use;
  63         unsigned visited;
  64 } be_use_t;
  65
  66 struct _be_uses_t {
  67         set *uses;
  68         ir_graph *irg;
  69         const be_lv_t *lv;
  70         unsigned visited_counter;
  71         DEBUG_ONLY(firm_dbg_module_t *dbg;)
  72 };
  73
  74 static int cmp_use(const void *a, const void *b, size_t n)
  75 {
  76         const be_use_t *p = a;
  77         const be_use_t *q = b;
  78         return !(p->block == q->block && p->node == q->node);
  79 }
  80
  81 static be_next_use_t get_next_use(be_uses_t *env, ir_node *from,
  82                                                                   unsigned from_step, const ir_node *def,
  83                                                                   int skip_from_uses);
  84
  85 static const be_use_t *get_or_set_use_block(be_uses_t *env,
  86                                             const ir_node *block,
  87                                             const ir_node *def)
  88 {
  89         unsigned hash = HASH_COMBINE(nodeset_hash(block), nodeset_hash(def));
  90         be_use_t temp;
  91         be_use_t* result;
  92
  93         temp.block = block;
  94         temp.node = def;
  95         result = set_find(env->uses, &temp, sizeof(temp), hash);
  96
  97         if(result == NULL) {
  98                 // insert templ first as we might end in a loop in the get_next_use
  99                 // call otherwise
 100                 temp.next_use = USES_INFINITY;
 101                 temp.outermost_loop = -1;
 102                 temp.visited = 0;
 103                 result = set_insert(env->uses, &temp, sizeof(temp), hash);
 104         }
 105
 106         if(result->outermost_loop < 0 && result->visited < env->visited_counter) {
 107                 be_next_use_t next_use;
 108
 109                 result->visited = env->visited_counter;
 110                 next_use = get_next_use(env, sched_first(block), 0, def, 0);
 111                 if(next_use.outermost_loop >= 0) {
 112                         result->next_use = next_use.time;
 113                         result->outermost_loop = next_use.outermost_loop;
 114                         DBG((env->dbg, LEVEL_5, "Setting nextuse of %+F in block %+F to %u (outermostloop %d)\n", def, block, result->next_use, result->outermost_loop));
 115                 }
 116         }
 117
 118         return result;
 119 }
 120
 121 static int be_is_phi_argument(const be_lv_t *lv, const ir_node *block, const ir_node *def)
 122 {
 123         ir_node *node;
 124         ir_node *succ_block = NULL;
 125         const ir_edge_t *edge;
 126         int arity, i;
 127
 128 #if 0
 129         if(get_irn_n_edges_kind(block, EDGE_KIND_BLOCK) > 1)
 130                 return 0;
 131 #endif
 132
 133         foreach_block_succ(block, edge) {
 134                 succ_block = get_edge_src_irn(edge);
 135                 break;
 136         }
 137
 138         arity = get_Block_n_cfgpreds(succ_block);
 139         if(arity <= 1)
 140                 return 0;
 141
 142         for(i = 0; i < arity; ++i) {
 143                 if(get_Block_cfgpred_block(succ_block, i) == block)
 144                         break;
 145         }
 146         assert(i < arity);
 147
 148         sched_foreach(succ_block, node) {
 149                 ir_node *arg;
 150
 151                 if(!is_Phi(node))
 152                         break;
 153
 154                 arg = get_irn_n(node, i);
 155                 if(arg == def)
 156                         return 1;
 157         }
 158
 159         return 0;
 160 }
 161
 162 static INLINE
 163 unsigned get_step(const ir_node *node)
 164 {
 165         return PTR_TO_INT(get_irn_link(node));
 166 }
 167
 168 static be_next_use_t get_next_use(be_uses_t *env, ir_node *from,
 169                                                                   unsigned from_step, const ir_node *def,
 170                                                                   int skip_from_uses)
 171 {
 172         unsigned  step = from_step;
 173         ir_node  *block = get_nodes_block(from);
 174         ir_node  *next_use;
 175         ir_node  *node;
 176         unsigned  timestep;
 177         unsigned  next_use_step;
 178         const ir_edge_t *edge;
 179
 180 #if 1
 181         assert(skip_from_uses == 0 || skip_from_uses == 1);
 182         if(skip_from_uses) {
 183                 from = sched_next(from);
 184         }
 185
 186         next_use      = NULL;
 187         next_use_step = INT_MAX;
 188         timestep      = get_step(from);
 189         foreach_out_edge(def, edge) {
 190                 ir_node  *node = get_edge_src_irn(edge);
 191                 unsigned  node_step;
 192
 193                 if(get_nodes_block(node) != block)
 194                         continue;
 195                 if(is_Phi(node))
 196                         continue;
 197
 198                 node_step = get_step(node);
 199                 if(node_step < timestep)
 200                         continue;
 201                 if(node_step < next_use_step) {
 202                         next_use      = node;
 203                         next_use_step = node_step;
 204                 }
 205         }
 206
 207         if(next_use != NULL) {
 208                 be_next_use_t result;
 209                 result.time           = next_use_step - timestep + skip_from_uses;
 210                 result.outermost_loop = get_loop_depth(get_irn_loop(block));
 211                 return result;
 212         }
 213
 214         node = sched_last(block);
 215         step = get_step(node) + 1 + timestep + skip_from_uses;
 216
 217 #else
 218         if(skip_from_uses) {
 219                 from = sched_next(from);
 220                 ++step;
 221         }
 222
 223         sched_foreach_from(from, node) {
 224                 int i, arity;
 225
 226                 if(is_Phi(node)) {
 227                         step++;
 228                         continue;
 229                 }
 230
 231                 arity = get_irn_arity(node);
 232                 for (i = 0; i < arity; ++i) {
 233                         const ir_node *operand = get_irn_n(node, i);
 234
 235                         if (operand == def) {
 236                                 be_next_use_t result;
 237
 238                                 DBG((env->dbg, LEVEL_3, "found use of %+F at %+F\n", operand, node));
 239
 240                                 /**
 241                                  * Spills/Reloads are a special case, they're not really a
 242                                  * usage of a value, continue searching
 243                                  */
 244                                 if (be_is_Spill(node) || be_is_Reload(node)) {
 245                                         return be_get_next_use(env, node, step, node, 1);
 246                                 }
 247
 248                                 result.time = step;
 249                                 result.outermost_loop = get_loop_depth(get_irn_loop(block));
 250                                 return result;
 251                         }
 252                 }
 253
 254                 step++;
 255         }
 256 #endif
 257
 258         if(be_is_phi_argument(env->lv, block, def)) {
 259                 // TODO we really should continue searching the uses of the phi,
 260                 // as a phi isn't a real use that implies a reload (because we could
 261                 // easily spill the whole phi)
 262
 263                 be_next_use_t result;
 264                 result.time           = step;
 265                 result.outermost_loop = get_loop_depth(get_irn_loop(block));
 266                 return result;
 267         }
 268
 269 #ifdef SCAN_INTERBLOCK_USES
 270         {
 271         unsigned next_use   = USES_INFINITY;
 272         int outermost_loop;
 273         be_next_use_t result;
 274         ir_loop *loop       = get_irn_loop(block);
 275         int loopdepth       = get_loop_depth(loop);
 276         int found_visited   = 0;
 277         int found_use       = 0;
 278         ir_graph *irg       = get_irn_irg(block);
 279         ir_node *startblock = get_irg_start_block(irg);
 280
 281         outermost_loop = loopdepth;
 282         foreach_block_succ(block, edge) {
 283                 const be_use_t *use;
 284                 const ir_node *succ_block = get_edge_src_irn(edge);
 285                 ir_loop *succ_loop;
 286                 unsigned use_dist;
 287
 288                 if(succ_block == startblock)
 289                         continue;
 290
 291                 DBG((env->dbg, LEVEL_5, "Checking succ of block %+F: %+F (for use of %+F)\n", block, succ_block, def));
 292                 if(!be_is_live_in(env->lv, succ_block, def)) {
 293                         //next_use = USES_INFINITY;
 294                         DBG((env->dbg, LEVEL_5, "   not live in\n"));
 295                         continue;
 296                 }
 297
 298                 use = get_or_set_use_block(env, succ_block, def);
 299                 DBG((env->dbg, LEVEL_5, "Found %u (loopdepth %d) (we're in block %+F)\n", use->next_use,
 300                                         use->outermost_loop, block));
 301                 if(USES_IS_INFINITE(use->next_use)) {
 302                         if(use->outermost_loop < 0) {
 303                                 found_visited = 1;
 304                         }
 305                         continue;
 306                 }
 307
 308                 found_use = 1;
 309                 use_dist = use->next_use;
 310
 311                 succ_loop = get_irn_loop(succ_block);
 312                 if(get_loop_depth(succ_loop) < loopdepth) {
 313                         unsigned factor = (loopdepth - get_loop_depth(succ_loop)) * 5000;
 314                         DBG((env->dbg, LEVEL_5, "Increase usestep because of loop out edge %d -> %d (%u)\n", factor));
 315                         // TODO we should use the number of nodes in the loop or so...
 316                         use_dist += factor;
 317                 }
 318
 319                 if(use_dist < next_use) {
 320                         next_use = use_dist;
 321                         outermost_loop = use->outermost_loop;
 322                 }
 323         }
 324
 325         if(loopdepth < outermost_loop)
 326                 outermost_loop = loopdepth;
 327
 328         result.time = next_use + step;
 329         result.outermost_loop = outermost_loop;
 330
 331         if(!found_use && found_visited) {
 332                 // the current result is correct for the current search, but isn't
 333                 // generally correct, so mark it
 334                 result.outermost_loop = -1;
 335         }
 336         DBG((env->dbg, LEVEL_5, "Result: %d (outerloop: %d)\n", result.time, result.outermost_loop));
 337         return result;
 338         }
 339 #else
 340         return USES_INFINITY;
 341 #endif
 342 }
 343
 344 be_next_use_t be_get_next_use(be_uses_t *env, ir_node *from,
 345                          unsigned from_step, const ir_node *def,
 346                          int skip_from_uses)
 347 {
 348         env->visited_counter++;
 349         return get_next_use(env, from, from_step, def, skip_from_uses);
 350 }
 351
 352 static
 353 void set_sched_step_walker(ir_node *block, void *data)
 354 {
 355         ir_node  *node;
 356         unsigned step = 0;
 357
 358         sched_foreach(block, node) {
 359                 set_irn_link(node, INT_TO_PTR(step));
 360                 if(is_Phi(node))
 361                         continue;
 362                 if(is_Proj(node))
 363                         continue;
 364                 ++step;
 365         }
 366 }
 367
 368 be_uses_t *be_begin_uses(ir_graph *irg, const be_lv_t *lv)
 369 {
 370         be_uses_t *env = xmalloc(sizeof(env[0]));
 371
 372         edges_assure(irg);
 373
 374         //set_using_irn_link(irg);
 375
 376         /* precalculate sched steps */
 377         irg_block_walk_graph(irg, set_sched_step_walker, NULL, NULL);
 378
 379         env->uses = new_set(cmp_use, 512);
 380         env->irg = irg;
 381         env->lv = lv;
 382         env->visited_counter = 0;
 383         FIRM_DBG_REGISTER(env->dbg, "firm.be.uses");
 384
 385         return env;
 386 }
 387
 388 void be_end_uses(be_uses_t *env)
 389 {
 390         //clear_using_irn_link(env->irg);
 391         del_set(env->uses);
 392         free(env);
 393 }