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   beuse.c
  22  * @date   27.06.2005
  23  * @author Sebastian Hack, Matthias Braun
  24  *
  25  * Methods to compute when a value will be used again.
  26  *
  27  * Copyright (C) 2005 Universitaet Karlsruhe
  28  * Released under the GPL
  29  */
  30 #ifdef HAVE_CONFIG_H
  31 #include "config.h"
  32 #endif
  33
  34 #include <limits.h>
  35 #include <stdlib.h>
  36
  37 #include "config.h"
  38 #include "obst.h"
  39 #include "pmap.h"
  40 #include "debug.h"
  41
  42 #include "irgwalk.h"
  43 #include "irnode_t.h"
  44 #include "ircons_t.h"
  45 #include "irgraph_t.h"
  46 #include "iredges_t.h"
  47 #include "irdom_t.h"
  48
  49 #include "be_t.h"
  50 #include "beutil.h"
  51 #include "belive_t.h"
  52 #include "benode_t.h"
  53 #include "besched_t.h"
  54 #include "beirgmod.h"
  55 #include "bearch_t.h"
  56 #include "beuses_t.h"
  57 #include "benodesets.h"
  58
  59 #define SCAN_INTERBLOCK_USES
  60
  61 typedef struct _be_use_t {
  62         const ir_node *block;
  63         const ir_node *node;
  64         int outermost_loop;
  65         unsigned next_use;
  66         unsigned visited;
  67 } be_use_t;
  68
  69 struct _be_uses_t {
  70         set *uses;
  71         ir_graph *irg;
  72         const be_lv_t *lv;
  73         unsigned visited_counter;
  74         DEBUG_ONLY(firm_dbg_module_t *dbg;)
  75 };
  76
  77 static int cmp_use(const void *a, const void *b, size_t n)
  78 {
  79         const be_use_t *p = a;
  80         const be_use_t *q = b;
  81         return !(p->block == q->block && p->node == q->node);
  82 }
  83
  84 static be_next_use_t get_next_use(be_uses_t *env, ir_node *from,
  85                                                                   unsigned from_step, const ir_node *def,
  86                                                                   int skip_from_uses);
  87
  88 static const be_use_t *get_or_set_use_block(be_uses_t *env,
  89                                             const ir_node *block,
  90                                             const ir_node *def)
  91 {
  92         unsigned hash = HASH_COMBINE(nodeset_hash(block), nodeset_hash(def));
  93         be_use_t temp;
  94         be_use_t* result;
  95
  96         temp.block = block;
  97         temp.node = def;
  98         result = set_find(env->uses, &temp, sizeof(temp), hash);
  99
 100         if(result == NULL) {
 101                 // insert templ first as we might end in a loop in the get_next_use
 102                 // call otherwise
 103                 temp.next_use = USES_INFINITY;
 104                 temp.outermost_loop = -1;
 105                 temp.visited = 0;
 106                 result = set_insert(env->uses, &temp, sizeof(temp), hash);
 107         }
 108
 109         if(result->outermost_loop < 0 && result->visited < env->visited_counter) {
 110                 be_next_use_t next_use;
 111
 112                 result->visited = env->visited_counter;
 113                 next_use = get_next_use(env, sched_first(block), 0, def, 0);
 114                 if(next_use.outermost_loop >= 0) {
 115                         result->next_use = next_use.time;
 116                         result->outermost_loop = next_use.outermost_loop;
 117                         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));
 118                 }
 119         }
 120
 121         return result;
 122 }
 123
 124 static int be_is_phi_argument(const be_lv_t *lv, const ir_node *block, const ir_node *def)
 125 {
 126         ir_node *node;
 127         ir_node *succ_block = NULL;
 128         const ir_edge_t *edge;
 129         int arity, i;
 130
 131 #if 0
 132         if(get_irn_n_edges_kind(block, EDGE_KIND_BLOCK) > 1)
 133                 return 0;
 134 #endif
 135
 136         foreach_block_succ(block, edge) {
 137                 succ_block = get_edge_src_irn(edge);
 138                 break;
 139         }
 140
 141         arity = get_Block_n_cfgpreds(succ_block);
 142         if(arity <= 1)
 143                 return 0;
 144
 145         for(i = 0; i < arity; ++i) {
 146                 if(get_Block_cfgpred_block(succ_block, i) == block)
 147                         break;
 148         }
 149         assert(i < arity);
 150
 151         sched_foreach(succ_block, node) {
 152                 ir_node *arg;
 153
 154                 if(!is_Phi(node))
 155                         break;
 156
 157                 arg = get_irn_n(node, i);
 158                 if(arg == def)
 159                         return 1;
 160         }
 161
 162         return 0;
 163 }
 164
 165 static be_next_use_t get_next_use(be_uses_t *env, ir_node *from,
 166                                                                   unsigned from_step, const ir_node *def,
 167                                                                   int skip_from_uses)
 168 {
 169         unsigned step = from_step;
 170         ir_node *block = get_nodes_block(from);
 171         ir_node *node;
 172         const ir_edge_t *edge;
 173
 174         if(skip_from_uses) {
 175                 step++;
 176                 from = sched_next(from);
 177         }
 178
 179         sched_foreach_from(from, node) {
 180                 int i, arity;
 181
 182                 if(is_Phi(node)) {
 183                         step++;
 184                         continue;
 185                 }
 186
 187                 arity = get_irn_arity(node);
 188                 for (i = 0; i < arity; ++i) {
 189                         const ir_node *operand = get_irn_n(node, i);
 190
 191                         if (operand == def) {
 192                                 be_next_use_t result;
 193
 194                                 DBG((env->dbg, LEVEL_3, "found use of %+F at %+F\n", operand, node));
 195
 196                                 /**
 197                                  * Spills/Reloads are a special case, they're not really a
 198                                  * usage of a value, continue searching
 199                                  */
 200                                 if (be_is_Spill(node) || be_is_Reload(node)) {
 201                                         return be_get_next_use(env, node, step, node, 1);
 202                                 }
 203
 204                                 result.time = step;
 205                                 result.outermost_loop = get_loop_depth(get_irn_loop(block));
 206                                 return result;
 207                         }
 208                 }
 209
 210                 step++;
 211         }
 212
 213         if(be_is_phi_argument(env->lv, block, def)) {
 214                 // TODO we really should continue searching the uses of the phi,
 215                 // as a phi isn't a real use that implies a reload (because we could
 216                 // easily spill the whole phi)
 217
 218                 be_next_use_t result;
 219                 result.time = step;
 220                 result.outermost_loop = get_loop_depth(get_irn_loop(block));
 221                 return result;
 222         }
 223
 224 #ifdef SCAN_INTERBLOCK_USES
 225         {
 226         unsigned next_use = USES_INFINITY;
 227         int outermost_loop;
 228         be_next_use_t result;
 229         ir_loop *loop = get_irn_loop(block);
 230         int loopdepth = get_loop_depth(loop);
 231         int found_visited = 0;
 232         int found_use = 0;
 233         ir_graph *irg = get_irn_irg(block);
 234         ir_node *startblock = get_irg_start_block(irg);
 235
 236         outermost_loop = loopdepth;
 237         foreach_block_succ(block, edge) {
 238                 const be_use_t *use;
 239                 const ir_node *succ_block = get_edge_src_irn(edge);
 240                 ir_loop *succ_loop;
 241                 unsigned use_dist;
 242
 243                 if(succ_block == startblock)
 244                         continue;
 245
 246                 DBG((env->dbg, LEVEL_5, "Checking succ of block %+F: %+F (for use of %+F)\n", block, succ_block, def));
 247                 if(!be_is_live_in(env->lv, succ_block, def)) {
 248                         //next_use = USES_INFINITY;
 249                         DBG((env->dbg, LEVEL_5, "   not live in\n"));
 250                         continue;
 251                 }
 252
 253                 use = get_or_set_use_block(env, succ_block, def);
 254                 DBG((env->dbg, LEVEL_5, "Found %u (loopdepth %d) (we're in block %+F)\n", use->next_use,
 255                                         use->outermost_loop, block));
 256                 if(USES_IS_INFINITE(use->next_use)) {
 257                         if(use->outermost_loop < 0) {
 258                                 found_visited = 1;
 259                         }
 260                         continue;
 261                 }
 262
 263                 found_use = 1;
 264                 use_dist = use->next_use;
 265
 266                 succ_loop = get_irn_loop(succ_block);
 267                 if(get_loop_depth(succ_loop) < loopdepth) {
 268                         unsigned factor = (loopdepth - get_loop_depth(succ_loop)) * 5000;
 269                         DBG((env->dbg, LEVEL_5, "Increase usestep because of loop out edge %d -> %d (%u)\n", factor));
 270                         // TODO we should use the number of nodes in the loop or so...
 271                         use_dist += factor;
 272                 }
 273
 274                 if(use_dist < next_use) {
 275                         next_use = use_dist;
 276                         outermost_loop = use->outermost_loop;
 277                 }
 278         }
 279
 280         if(loopdepth < outermost_loop)
 281                 outermost_loop = loopdepth;
 282
 283         result.time = next_use + step;
 284         result.outermost_loop = outermost_loop;
 285
 286         if(!found_use && found_visited) {
 287                 // the current result is correct for the current search, but isn't
 288                 // generally correct, so mark it
 289                 result.outermost_loop = -1;
 290         }
 291         DBG((env->dbg, LEVEL_5, "Result: %d (outerloop: %d)\n", result.time, result.outermost_loop));
 292         return result;
 293         }
 294 #else
 295         return USES_INFINITY;
 296 #endif
 297 }
 298
 299 be_next_use_t be_get_next_use(be_uses_t *env, ir_node *from,
 300                          unsigned from_step, const ir_node *def,
 301                          int skip_from_uses)
 302 {
 303         env->visited_counter++;
 304         return get_next_use(env, from, from_step, def, skip_from_uses);
 305 }
 306
 307 be_uses_t *be_begin_uses(ir_graph *irg, const be_lv_t *lv)
 308 {
 309         be_uses_t *env = xmalloc(sizeof(env[0]));
 310
 311         edges_assure(irg);
 312
 313         env->uses = new_set(cmp_use, 512);
 314         env->irg = irg;
 315         env->lv = lv;
 316         env->visited_counter = 0;
 317         FIRM_DBG_REGISTER(env->dbg, "firm.be.uses");
 318
 319         return env;
 320 }
 321
 322 void be_end_uses(be_uses_t *env)
 323 {
 324         del_set(env->uses);
 325         free(env);
 326 }