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