nsz Git - libfirm/blob - ir/be/beuses.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       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
  55 #define SCAN_INTERBLOCK_USES
  56
  57 typedef struct _be_use_t {
  58         const ir_node *block;
  59         const ir_node *node;
  60         int outermost_loop;
  61         unsigned next_use;
  62         unsigned visited;
  63 } be_use_t;
  64
  65 struct _be_uses_t {
  66         set *uses;
  67         ir_graph *irg;
  68         const be_lv_t *lv;
  69         unsigned visited_counter;
  70         DEBUG_ONLY(firm_dbg_module_t *dbg;)
  71 };
  72
  73 static int cmp_use(const void *a, const void *b, size_t n)
  74 {
  75         const be_use_t *p = a;
  76         const be_use_t *q = b;
  77         (void) n;
  78
  79         return !(p->block == q->block && p->node == q->node);
  80 }
  81
  82 static be_next_use_t get_next_use(be_uses_t *env, ir_node *from,
  83                                                                   unsigned from_step, const ir_node *def,
  84                                                                   int skip_from_uses);
  85
  86 static const be_use_t *get_or_set_use_block(be_uses_t *env,
  87                                             const ir_node *block,
  88                                             const ir_node *def)
  89 {
  90         unsigned hash = HASH_COMBINE(hash_irn(block), hash_irn(def));
  91         be_use_t temp;
  92         be_use_t* result;
  93
  94         temp.block = block;
  95         temp.node = def;
  96         result = set_find(env->uses, &temp, sizeof(temp), hash);
  97
  98         if(result == NULL) {
  99                 // insert templ first as we might end in a loop in the get_next_use
 100                 // call otherwise
 101                 temp.next_use = USES_INFINITY;
 102                 temp.outermost_loop = -1;
 103                 temp.visited = 0;
 104                 result = set_insert(env->uses, &temp, sizeof(temp), hash);
 105         }
 106
 107         if(result->outermost_loop < 0 && result->visited < env->visited_counter) {
 108                 be_next_use_t next_use;
 109
 110                 result->visited = env->visited_counter;
 111                 next_use = get_next_use(env, sched_first(block), 0, def, 0);
 112                 if(next_use.outermost_loop >= 0) {
 113                         result->next_use = next_use.time;
 114                         result->outermost_loop = next_use.outermost_loop;
 115                         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));
 116                 }
 117         }
 118
 119         return result;
 120 }
 121
 122 static int be_is_phi_argument(const ir_node *block, const ir_node *def)
 123 {
 124         ir_node *node;
 125         ir_node *succ_block = NULL;
 126         const ir_edge_t *edge;
 127         int arity, i;
 128
 129 #if 0
 130         if(get_irn_n_edges_kind(block, EDGE_KIND_BLOCK) > 1)
 131                 return 0;
 132 #endif
 133
 134         foreach_block_succ(block, edge) {
 135                 succ_block = get_edge_src_irn(edge);
 136                 break;
 137         }
 138
 139         arity = get_Block_n_cfgpreds(succ_block);
 140         if(arity <= 1)
 141                 return 0;
 142
 143         for(i = 0; i < arity; ++i) {
 144                 if(get_Block_cfgpred_block(succ_block, i) == block)
 145                         break;
 146         }
 147         assert(i < arity);
 148
 149         sched_foreach(succ_block, node) {
 150                 ir_node *arg;
 151
 152                 if(!is_Phi(node))
 153                         break;
 154
 155                 arg = get_irn_n(node, i);
 156                 if(arg == def)
 157                         return 1;
 158         }
 159
 160         return 0;
 161 }
 162
 163 static INLINE
 164 unsigned get_step(const ir_node *node)
 165 {
 166         return PTR_TO_INT(get_irn_link(node));
 167 }
 168
 169 static be_next_use_t get_next_use(be_uses_t *env, ir_node *from,
 170                                                                   unsigned from_step, const ir_node *def,
 171                                                                   int skip_from_uses)
 172 {
 173         unsigned  step  = from_step;
 174         ir_node  *block = get_nodes_block(from);
 175         ir_node  *next_use;
 176         ir_node  *node;
 177         unsigned  timestep;
 178         unsigned  next_use_step;
 179         const ir_edge_t *edge;
 180
 181 #if 1
 182         assert(skip_from_uses == 0 || skip_from_uses == 1);
 183         if(skip_from_uses) {
 184                 from = sched_next(from);
 185         }
 186
 187         next_use      = NULL;
 188         next_use_step = INT_MAX;
 189         timestep      = get_step(from);
 190         foreach_out_edge(def, edge) {
 191                 ir_node  *node = get_edge_src_irn(edge);
 192                 unsigned  node_step;
 193
 194                 if(is_Anchor(node))
 195                         continue;
 196                 if(get_nodes_block(node) != block)
 197                         continue;
 198                 if(is_Phi(node))
 199                         continue;
 200
 201                 node_step = get_step(node);
 202                 if(node_step < timestep)
 203                         continue;
 204                 if(node_step < next_use_step) {
 205                         next_use      = node;
 206                         next_use_step = node_step;
 207                 }
 208         }
 209
 210         if(next_use != NULL) {
 211                 be_next_use_t result;
 212                 result.time           = next_use_step - timestep + skip_from_uses;
 213                 result.outermost_loop = get_loop_depth(get_irn_loop(block));
 214                 result.before         = next_use;
 215                 return result;
 216         }
 217
 218         node = sched_last(block);
 219         step = get_step(node) + 1 + timestep + skip_from_uses;
 220
 221 #else
 222         if(skip_from_uses) {
 223                 from = sched_next(from);
 224                 ++step;
 225         }
 226
 227         sched_foreach_from(from, node) {
 228                 int i, arity;
 229
 230                 if(is_Phi(node)) {
 231                         step++;
 232                         continue;
 233                 }
 234
 235                 arity = get_irn_arity(node);
 236                 for (i = 0; i < arity; ++i) {
 237                         const ir_node *operand = get_irn_n(node, i);
 238
 239                         if (operand == def) {
 240                                 be_next_use_t result;
 241
 242                                 DBG((env->dbg, LEVEL_3, "found use of %+F at %+F\n", operand, node));
 243
 244                                 /**
 245                                  * Spills/Reloads are a special case, they're not really a
 246                                  * usage of a value, continue searching
 247                                  */
 248                                 if (be_is_Spill(node) || be_is_Reload(node)) {
 249                                         return be_get_next_use(env, node, step, node, 1);
 250                                 }
 251
 252                                 result.time           = step;
 253                                 result.outermost_loop = get_loop_depth(get_irn_loop(block));
 254                                 result.before         = node;
 255                                 return result;
 256                         }
 257                 }
 258
 259                 step++;
 260         }
 261 #endif
 262
 263         if(be_is_phi_argument(block, def)) {
 264                 // TODO we really should continue searching the uses of the phi,
 265                 // as a phi isn't a real use that implies a reload (because we could
 266                 // easily spill the whole phi)
 267
 268                 be_next_use_t result;
 269                 result.time           = step;
 270                 result.outermost_loop = get_loop_depth(get_irn_loop(block));
 271                 result.before         = block;
 272                 return result;
 273         }
 274
 275 #ifdef SCAN_INTERBLOCK_USES
 276         {
 277         unsigned next_use   = USES_INFINITY;
 278         int outermost_loop;
 279         be_next_use_t result;
 280         ir_loop *loop       = get_irn_loop(block);
 281         int loopdepth       = get_loop_depth(loop);
 282         int found_visited   = 0;
 283         int found_use       = 0;
 284         ir_graph *irg       = get_irn_irg(block);
 285         ir_node *startblock = get_irg_start_block(irg);
 286
 287         result.before  = NULL;
 288         outermost_loop = loopdepth;
 289         foreach_block_succ(block, edge) {
 290                 const be_use_t *use;
 291                 const ir_node *succ_block = get_edge_src_irn(edge);
 292                 ir_loop *succ_loop;
 293                 unsigned use_dist;
 294
 295                 if(succ_block == startblock)
 296                         continue;
 297
 298                 DBG((env->dbg, LEVEL_5, "Checking succ of block %+F: %+F (for use of %+F)\n", block, succ_block, def));
 299                 if(!be_is_live_in(env->lv, succ_block, def)) {
 300                         //next_use = USES_INFINITY;
 301                         DBG((env->dbg, LEVEL_5, "   not live in\n"));
 302                         continue;
 303                 }
 304
 305                 use = get_or_set_use_block(env, succ_block, def);
 306                 DBG((env->dbg, LEVEL_5, "Found %u (loopdepth %d) (we're in block %+F)\n", use->next_use,
 307                                         use->outermost_loop, block));
 308                 if(USES_IS_INFINITE(use->next_use)) {
 309                         if(use->outermost_loop < 0) {
 310                                 found_visited = 1;
 311                         }
 312                         continue;
 313                 }
 314
 315                 found_use = 1;
 316                 use_dist = use->next_use;
 317
 318                 succ_loop = get_irn_loop(succ_block);
 319                 if(get_loop_depth(succ_loop) < loopdepth) {
 320                         unsigned factor = (loopdepth - get_loop_depth(succ_loop)) * 5000;
 321                         DBG((env->dbg, LEVEL_5, "Increase usestep because of loop out edge %d -> %d (%u)\n", factor));
 322                         // TODO we should use the number of nodes in the loop or so...
 323                         use_dist += factor;
 324                 }
 325
 326                 if(use_dist < next_use) {
 327                         next_use       = use_dist;
 328                         outermost_loop = use->outermost_loop;
 329                         result.before  = use->node;
 330                 }
 331         }
 332
 333         if(loopdepth < outermost_loop)
 334                 outermost_loop = loopdepth;
 335
 336         result.time           = next_use + step;
 337         result.outermost_loop = outermost_loop;
 338
 339         if(!found_use && found_visited) {
 340                 // the current result is correct for the current search, but isn't
 341                 // generally correct, so mark it
 342                 result.outermost_loop = -1;
 343         }
 344         DBG((env->dbg, LEVEL_5, "Result: %d (outerloop: %d)\n", result.time, result.outermost_loop));
 345         return result;
 346         }
 347 #else
 348         return USES_INFINITY;
 349 #endif
 350 }
 351
 352 be_next_use_t be_get_next_use(be_uses_t *env, ir_node *from,
 353                          unsigned from_step, const ir_node *def,
 354                          int skip_from_uses)
 355 {
 356         env->visited_counter++;
 357         return get_next_use(env, from, from_step, def, skip_from_uses);
 358 }
 359
 360 static
 361 void set_sched_step_walker(ir_node *block, void *data)
 362 {
 363         ir_node  *node;
 364         unsigned step = 0;
 365         (void) data;
 366
 367         sched_foreach(block, node) {
 368                 set_irn_link(node, INT_TO_PTR(step));
 369                 if(is_Phi(node))
 370                         continue;
 371                 if(is_Proj(node))
 372                         continue;
 373                 ++step;
 374         }
 375 }
 376
 377 be_uses_t *be_begin_uses(ir_graph *irg, const be_lv_t *lv)
 378 {
 379         be_uses_t *env = xmalloc(sizeof(env[0]));
 380
 381         edges_assure(irg);
 382
 383         //set_using_irn_link(irg);
 384
 385         /* precalculate sched steps */
 386         irg_block_walk_graph(irg, set_sched_step_walker, NULL, NULL);
 387
 388         env->uses = new_set(cmp_use, 512);
 389         env->irg = irg;
 390         env->lv = lv;
 391         env->visited_counter = 0;
 392         FIRM_DBG_REGISTER(env->dbg, "firm.be.uses");
 393
 394         return env;
 395 }
 396
 397 void be_end_uses(be_uses_t *env)
 398 {
 399         //clear_using_irn_link(env->irg);
 400         del_set(env->uses);
 401         free(env);
 402 }