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 be_next_use_t get_next_use(be_uses_t *env, ir_node *from,
 163                                                                   unsigned from_step, const ir_node *def,
 164                                                                   int skip_from_uses)
 165 {
 166         unsigned step = from_step;
 167         ir_node *block = get_nodes_block(from);
 168         ir_node *node;
 169         const ir_edge_t *edge;
 170
 171         if(skip_from_uses) {
 172                 step++;
 173                 from = sched_next(from);
 174         }
 175
 176         sched_foreach_from(from, node) {
 177                 int i, arity;
 178
 179                 if(is_Phi(node)) {
 180                         step++;
 181                         continue;
 182                 }
 183
 184                 arity = get_irn_arity(node);
 185                 for (i = 0; i < arity; ++i) {
 186                         const ir_node *operand = get_irn_n(node, i);
 187
 188                         if (operand == def) {
 189                                 be_next_use_t result;
 190
 191                                 DBG((env->dbg, LEVEL_3, "found use of %+F at %+F\n", operand, node));
 192
 193                                 /**
 194                                  * Spills/Reloads are a special case, they're not really a
 195                                  * usage of a value, continue searching
 196                                  */
 197                                 if (be_is_Spill(node) || be_is_Reload(node)) {
 198                                         return be_get_next_use(env, node, step, node, 1);
 199                                 }
 200
 201                                 result.time = step;
 202                                 result.outermost_loop = get_loop_depth(get_irn_loop(block));
 203                                 return result;
 204                         }
 205                 }
 206
 207                 step++;
 208         }
 209
 210         if(be_is_phi_argument(env->lv, block, def)) {
 211                 // TODO we really should continue searching the uses of the phi,
 212                 // as a phi isn't a real use that implies a reload (because we could
 213                 // easily spill the whole phi)
 214
 215                 be_next_use_t result;
 216                 result.time = step;
 217                 result.outermost_loop = get_loop_depth(get_irn_loop(block));
 218                 return result;
 219         }
 220
 221 #ifdef SCAN_INTERBLOCK_USES
 222         {
 223         unsigned next_use = USES_INFINITY;
 224         int outermost_loop;
 225         be_next_use_t result;
 226         ir_loop *loop = get_irn_loop(block);
 227         int loopdepth = get_loop_depth(loop);
 228         int found_visited = 0;
 229         int found_use = 0;
 230         ir_graph *irg = get_irn_irg(block);
 231         ir_node *startblock = get_irg_start_block(irg);
 232
 233         outermost_loop = loopdepth;
 234         foreach_block_succ(block, edge) {
 235                 const be_use_t *use;
 236                 const ir_node *succ_block = get_edge_src_irn(edge);
 237                 ir_loop *succ_loop;
 238                 unsigned use_dist;
 239
 240                 if(succ_block == startblock)
 241                         continue;
 242
 243                 DBG((env->dbg, LEVEL_5, "Checking succ of block %+F: %+F (for use of %+F)\n", block, succ_block, def));
 244                 if(!be_is_live_in(env->lv, succ_block, def)) {
 245                         //next_use = USES_INFINITY;
 246                         DBG((env->dbg, LEVEL_5, "   not live in\n"));
 247                         continue;
 248                 }
 249
 250                 use = get_or_set_use_block(env, succ_block, def);
 251                 DBG((env->dbg, LEVEL_5, "Found %u (loopdepth %d) (we're in block %+F)\n", use->next_use,
 252                                         use->outermost_loop, block));
 253                 if(USES_IS_INFINITE(use->next_use)) {
 254                         if(use->outermost_loop < 0) {
 255                                 found_visited = 1;
 256                         }
 257                         continue;
 258                 }
 259
 260                 found_use = 1;
 261                 use_dist = use->next_use;
 262
 263                 succ_loop = get_irn_loop(succ_block);
 264                 if(get_loop_depth(succ_loop) < loopdepth) {
 265                         unsigned factor = (loopdepth - get_loop_depth(succ_loop)) * 5000;
 266                         DBG((env->dbg, LEVEL_5, "Increase usestep because of loop out edge %d -> %d (%u)\n", factor));
 267                         // TODO we should use the number of nodes in the loop or so...
 268                         use_dist += factor;
 269                 }
 270
 271                 if(use_dist < next_use) {
 272                         next_use = use_dist;
 273                         outermost_loop = use->outermost_loop;
 274                 }
 275         }
 276
 277         if(loopdepth < outermost_loop)
 278                 outermost_loop = loopdepth;
 279
 280         result.time = next_use + step;
 281         result.outermost_loop = outermost_loop;
 282
 283         if(!found_use && found_visited) {
 284                 // the current result is correct for the current search, but isn't
 285                 // generally correct, so mark it
 286                 result.outermost_loop = -1;
 287         }
 288         DBG((env->dbg, LEVEL_5, "Result: %d (outerloop: %d)\n", result.time, result.outermost_loop));
 289         return result;
 290         }
 291 #else
 292         return USES_INFINITY;
 293 #endif
 294 }
 295
 296 be_next_use_t be_get_next_use(be_uses_t *env, ir_node *from,
 297                          unsigned from_step, const ir_node *def,
 298                          int skip_from_uses)
 299 {
 300         env->visited_counter++;
 301         return get_next_use(env, from, from_step, def, skip_from_uses);
 302 }
 303
 304 be_uses_t *be_begin_uses(ir_graph *irg, const be_lv_t *lv)
 305 {
 306         be_uses_t *env = xmalloc(sizeof(env[0]));
 307
 308         edges_assure(irg);
 309
 310         env->uses = new_set(cmp_use, 512);
 311         env->irg = irg;
 312         env->lv = lv;
 313         env->visited_counter = 0;
 314         FIRM_DBG_REGISTER(env->dbg, "firm.be.uses");
 315
 316         return env;
 317 }
 318
 319 void be_end_uses(be_uses_t *env)
 320 {
 321         del_set(env->uses);
 322         free(env);
 323 }