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 #include "config.h"
  28
  29 #include <limits.h>
  30 #include <stdlib.h>
  31
  32 #include "config.h"
  33 #include "obst.h"
  34 #include "pmap.h"
  35 #include "debug.h"
  36
  37 #include "irgwalk.h"
  38 #include "irnode_t.h"
  39 #include "ircons_t.h"
  40 #include "irgraph_t.h"
  41 #include "iredges_t.h"
  42 #include "irdom_t.h"
  43
  44 #include "be_t.h"
  45 #include "beutil.h"
  46 #include "belive_t.h"
  47 #include "benode.h"
  48 #include "besched.h"
  49 #include "beirgmod.h"
  50 #include "bearch.h"
  51 #include "beuses.h"
  52
  53 #define SCAN_INTERBLOCK_USES
  54
  55 typedef struct _be_use_t {
  56         const ir_node *block;
  57         const ir_node *node;
  58         int outermost_loop;
  59         unsigned next_use;
  60         unsigned visited;
  61 } be_use_t;
  62
  63 struct _be_uses_t {
  64         set *uses;
  65         ir_graph *irg;
  66         const be_lv_t *lv;
  67         unsigned visited_counter;
  68         DEBUG_ONLY(firm_dbg_module_t *dbg;)
  69 };
  70
  71 static int cmp_use(const void *a, const void *b, size_t n)
  72 {
  73         const be_use_t *p = a;
  74         const be_use_t *q = b;
  75         (void) n;
  76
  77         return !(p->block == q->block && p->node == q->node);
  78 }
  79
  80 static be_next_use_t get_next_use(be_uses_t *env, ir_node *from,
  81                                                                   unsigned from_step, const ir_node *def,
  82                                                                   int skip_from_uses);
  83
  84 static const be_use_t *get_or_set_use_block(be_uses_t *env,
  85                                             const ir_node *block,
  86                                             const ir_node *def)
  87 {
  88         unsigned hash = HASH_COMBINE(hash_irn(block), hash_irn(def));
  89         be_use_t temp;
  90         be_use_t* result;
  91
  92         temp.block = block;
  93         temp.node = def;
  94         result = set_find(env->uses, &temp, sizeof(temp), hash);
  95
  96         if (result == NULL) {
  97                 // insert templ first as we might end in a loop in the get_next_use
  98                 // call otherwise
  99                 temp.next_use = USES_INFINITY;
 100                 temp.outermost_loop = -1;
 101                 temp.visited = 0;
 102                 result = set_insert(env->uses, &temp, sizeof(temp), hash);
 103         }
 104
 105         if (result->outermost_loop < 0 && result->visited < env->visited_counter) {
 106                 be_next_use_t next_use;
 107
 108                 result->visited = env->visited_counter;
 109                 next_use = get_next_use(env, sched_first(block), 0, def, 0);
 110                 if (next_use.outermost_loop >= 0) {
 111                         result->next_use = next_use.time;
 112                         result->outermost_loop = next_use.outermost_loop;
 113                         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));
 114                 }
 115         }
 116
 117         return result;
 118 }
 119
 120 static int be_is_phi_argument(const ir_node *block, const ir_node *def)
 121 {
 122         ir_node *node;
 123         ir_node *succ_block = NULL;
 124         int arity, i;
 125
 126 #if 1
 127         if (get_irn_n_edges_kind(block, EDGE_KIND_BLOCK) < 1)
 128 #else
 129         if (get_irn_n_edges_kind(block, EDGE_KIND_BLOCK) != 1)
 130 #endif
 131                 return 0;
 132
 133         succ_block = get_first_block_succ(block);
 134
 135         arity = get_Block_n_cfgpreds(succ_block);
 136         if (arity <= 1)
 137                 return 0;
 138
 139         for (i = 0; i < arity; ++i) {
 140                 if (get_Block_cfgpred_block(succ_block, i) == block)
 141                         break;
 142         }
 143         assert(i < arity);
 144
 145         sched_foreach(succ_block, node) {
 146                 ir_node *arg;
 147
 148                 if (!is_Phi(node))
 149                         break;
 150
 151                 arg = get_irn_n(node, i);
 152                 if (arg == def)
 153                         return 1;
 154         }
 155
 156         return 0;
 157 }
 158
 159 static inline unsigned get_step(const ir_node *node)
 160 {
 161         return PTR_TO_INT(get_irn_link(node));
 162 }
 163
 164 static be_next_use_t get_next_use(be_uses_t *env, ir_node *from,
 165                                                                   unsigned from_step, const ir_node *def,
 166                                                                   int skip_from_uses)
 167 {
 168         unsigned  step  = from_step;
 169         ir_node  *block = get_nodes_block(from);
 170         ir_node  *next_use;
 171         ir_node  *node;
 172         unsigned  timestep;
 173         unsigned  next_use_step;
 174         const ir_edge_t *edge;
 175
 176 #if 1
 177         assert(skip_from_uses == 0 || skip_from_uses == 1);
 178         if (skip_from_uses) {
 179                 from = sched_next(from);
 180         }
 181
 182         next_use      = NULL;
 183         next_use_step = INT_MAX;
 184         timestep      = get_step(from);
 185         foreach_out_edge(def, edge) {
 186                 ir_node  *node = get_edge_src_irn(edge);
 187                 unsigned  node_step;
 188
 189                 if (is_Anchor(node))
 190                         continue;
 191                 if (get_nodes_block(node) != block)
 192                         continue;
 193                 if (is_Phi(node))
 194                         continue;
 195
 196                 node_step = get_step(node);
 197                 if (node_step < timestep)
 198                         continue;
 199                 if (node_step < next_use_step) {
 200                         next_use      = node;
 201                         next_use_step = node_step;
 202                 }
 203         }
 204
 205         if (next_use != NULL) {
 206                 be_next_use_t result;
 207                 result.time           = next_use_step - timestep + skip_from_uses;
 208                 result.outermost_loop = get_loop_depth(get_irn_loop(block));
 209                 result.before         = next_use;
 210                 return result;
 211         }
 212
 213         node = sched_last(block);
 214         step = get_step(node) + 1 + timestep + skip_from_uses;
 215
 216 #else
 217         if (skip_from_uses) {
 218                 from = sched_next(from);
 219                 ++step;
 220         }
 221
 222         sched_foreach_from(from, node) {
 223                 int i, arity;
 224
 225                 if (is_Phi(node)) {
 226                         step++;
 227                         continue;
 228                 }
 229
 230                 arity = get_irn_arity(node);
 231                 for (i = 0; i < arity; ++i) {
 232                         const ir_node *operand = get_irn_n(node, i);
 233
 234                         if (operand == def) {
 235                                 be_next_use_t result;
 236
 237                                 DBG((env->dbg, LEVEL_3, "found use of %+F at %+F\n", operand, node));
 238
 239                                 /**
 240                                  * Spills/Reloads are a special case, they're not really a
 241                                  * usage of a value, continue searching
 242                                  */
 243                                 if (be_is_Spill(node) || be_is_Reload(node)) {
 244                                         return be_get_next_use(env, node, step, node, 1);
 245                                 }
 246
 247                                 result.time           = step;
 248                                 result.outermost_loop = get_loop_depth(get_irn_loop(block));
 249                                 result.before         = node;
 250                                 return result;
 251                         }
 252                 }
 253
 254                 step++;
 255         }
 256 #endif
 257
 258         if (be_is_phi_argument(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                 result.before         = block;
 267                 return result;
 268         }
 269
 270 #ifdef SCAN_INTERBLOCK_USES
 271         {
 272         unsigned next_use   = USES_INFINITY;
 273         int outermost_loop;
 274         be_next_use_t result;
 275         ir_loop *loop       = get_irn_loop(block);
 276         int loopdepth       = get_loop_depth(loop);
 277         int found_visited   = 0;
 278         int found_use       = 0;
 279         ir_graph *irg       = get_irn_irg(block);
 280         ir_node *startblock = get_irg_start_block(irg);
 281
 282         result.before  = NULL;
 283         outermost_loop = loopdepth;
 284         foreach_block_succ(block, edge) {
 285                 const be_use_t *use;
 286                 const ir_node *succ_block = get_edge_src_irn(edge);
 287                 ir_loop *succ_loop;
 288                 unsigned use_dist;
 289
 290                 if (succ_block == startblock)
 291                         continue;
 292
 293                 DBG((env->dbg, LEVEL_5, "Checking succ of block %+F: %+F (for use of %+F)\n", block, succ_block, def));
 294                 if (!be_is_live_in(env->lv, succ_block, def)) {
 295                         //next_use = USES_INFINITY;
 296                         DBG((env->dbg, LEVEL_5, "   not live in\n"));
 297                         continue;
 298                 }
 299
 300                 use = get_or_set_use_block(env, succ_block, def);
 301                 DBG((env->dbg, LEVEL_5, "Found %u (loopdepth %d) (we're in block %+F)\n", use->next_use,
 302                                         use->outermost_loop, block));
 303                 if (USES_IS_INFINITE(use->next_use)) {
 304                         if (use->outermost_loop < 0) {
 305                                 found_visited = 1;
 306                         }
 307                         continue;
 308                 }
 309
 310                 found_use = 1;
 311                 use_dist = use->next_use;
 312
 313                 succ_loop = get_irn_loop(succ_block);
 314                 if (get_loop_depth(succ_loop) < loopdepth) {
 315                         unsigned factor = (loopdepth - get_loop_depth(succ_loop)) * 5000;
 316                         DBG((env->dbg, LEVEL_5, "Increase usestep because of loop out edge %d -> %d (%u)\n", factor));
 317                         // TODO we should use the number of nodes in the loop or so...
 318                         use_dist += factor;
 319                 }
 320
 321                 if (use_dist < next_use) {
 322                         next_use       = use_dist;
 323                         outermost_loop = use->outermost_loop;
 324                         result.before  = use->node;
 325                 }
 326         }
 327
 328         if (loopdepth < outermost_loop)
 329                 outermost_loop = loopdepth;
 330
 331         result.time           = next_use + step;
 332         result.outermost_loop = outermost_loop;
 333
 334         if (!found_use && found_visited) {
 335                 // the current result is correct for the current search, but isn't
 336                 // generally correct, so mark it
 337                 result.outermost_loop = -1;
 338         }
 339         DBG((env->dbg, LEVEL_5, "Result: %d (outerloop: %d)\n", result.time, result.outermost_loop));
 340         return result;
 341         }
 342 #else
 343         return USES_INFINITY;
 344 #endif
 345 }
 346
 347 be_next_use_t be_get_next_use(be_uses_t *env, ir_node *from,
 348                          unsigned from_step, const ir_node *def,
 349                          int skip_from_uses)
 350 {
 351         env->visited_counter++;
 352         return get_next_use(env, from, from_step, def, skip_from_uses);
 353 }
 354
 355 static void set_sched_step_walker(ir_node *block, void *data)
 356 {
 357         ir_node  *node;
 358         unsigned step = 0;
 359         (void) data;
 360
 361         sched_foreach(block, node) {
 362                 set_irn_link(node, INT_TO_PTR(step));
 363                 if (is_Phi(node))
 364                         continue;
 365                 ++step;
 366         }
 367 }
 368
 369 be_uses_t *be_begin_uses(ir_graph *irg, const be_lv_t *lv)
 370 {
 371         be_uses_t *env = XMALLOC(be_uses_t);
 372
 373         edges_assure(irg);
 374
 375         //set_using_irn_link(irg);
 376
 377         /* precalculate sched steps */
 378         irg_block_walk_graph(irg, set_sched_step_walker, NULL, NULL);
 379
 380         env->uses = new_set(cmp_use, 512);
 381         env->irg = irg;
 382         env->lv = lv;
 383         env->visited_counter = 0;
 384         FIRM_DBG_REGISTER(env->dbg, "firm.be.uses");
 385
 386         return env;
 387 }
 388
 389 void be_end_uses(be_uses_t *env)
 390 {
 391         //clear_using_irn_link(env->irg);
 392         del_set(env->uses);
 393         free(env);
 394 }