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