nsz Git - libfirm/blob - ir/be/bespilldaemel.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       Naiv spilling algorithm
  23  * @author      Matthias Braun
  24  * @date        20.09.2005
  25  * @version     $Id: bespillbelady.c 13913 2007-05-18 12:48:56Z matze $
  26  * @summary
  27  *   This implements a naiv spilling algorithm. It is design to produce similar
  28  *   effects to the spill decisions produced by traditional graph coloring
  29  *   register allocators that spill while they are coloring the graph.
  30  *
  31  *   This spiller walks over all blocks and looks for places with too high
  32  *   register pressure where it spills the values that are cheapest to spill.
  33  *   Spilling in this context means placing a spill instruction behind the
  34  *   definition of the value and a reload before each usage.
  35  */
  36 #ifdef HAVE_CONFIG_H
  37 #include "config.h"
  38 #endif
  39
  40 #include "debug.h"
  41
  42 #include "irnodeset.h"
  43 #include "irgwalk.h"
  44 #include "irprintf.h"
  45 #include "iredges_t.h"
  46 #include "error.h"
  47
  48 #include "beirg.h"
  49 #include "bespilloptions.h"
  50 #include "bespill.h"
  51 #include "bemodule.h"
  52 #include "besched.h"
  53 #include "bearch_t.h"
  54 #include "be_t.h"
  55 #include "benode_t.h"
  56 #include "beirg.h"
  57
  58 DEBUG_ONLY(static firm_dbg_module_t *dbg = NULL;)
  59
  60 typedef struct daemel_env_t daemel_env_t;
  61 struct daemel_env_t {
  62         spill_env_t                 *spill_env;
  63         int                          n_regs;
  64         const arch_env_t            *arch_env;
  65         const arch_register_class_t *cls;
  66         const be_lv_t               *lv;
  67         bitset_t                    *spilled_nodes;
  68 };
  69
  70 typedef struct spill_candidate_t spill_candidate_t;
  71 struct spill_candidate_t {
  72         double   costs;
  73         ir_node *node;
  74 };
  75
  76 static
  77 int compare_spill_candidates_desc(const void *d1, const void *d2)
  78 {
  79         const spill_candidate_t *c1 = d1;
  80         const spill_candidate_t *c2 = d2;
  81
  82         return (int) (c1->costs - c2->costs);
  83 }
  84
  85 static
  86 double get_spill_costs(daemel_env_t *env, ir_node *node)
  87 {
  88         const ir_edge_t *edge;
  89         spill_env_t     *spill_env = env->spill_env;
  90         double           costs     = be_get_spill_costs(spill_env, node, node);
  91
  92         foreach_out_edge(node, edge) {
  93                 ir_node *use = get_edge_src_irn(edge);
  94
  95                 if(is_Phi(use)) {
  96                         int      in         = get_edge_src_pos(edge);
  97                         ir_node *block      = get_nodes_block(use);
  98
  99                         costs += be_get_reload_costs_on_edge(spill_env, node, block, in);
 100                 } else {
 101                         costs += be_get_reload_costs(spill_env, node, use);
 102                 }
 103         }
 104
 105         return costs;
 106 }
 107
 108 /**
 109  * spills a node by placing a reload before each usage
 110  */
 111 static
 112 void spill_node(daemel_env_t *env, ir_node *node)
 113 {
 114         const ir_edge_t *edge;
 115         spill_env_t     *spill_env       = env->spill_env;
 116         const arch_register_class_t *cls = env->cls;
 117
 118         DBG((dbg, LEVEL_3, "\tspilling %+F\n", node));
 119
 120         foreach_out_edge(node, edge) {
 121                 ir_node *use = get_edge_src_irn(edge);
 122                 if(is_Anchor(use))
 123                         continue;
 124
 125                 if(is_Phi(use)) {
 126                         int      in         = get_edge_src_pos(edge);
 127                         ir_node *block      = get_nodes_block(use);
 128
 129                         be_add_reload_on_edge(spill_env, node, block, in, cls, 1);
 130                 } else if(!be_is_Keep(use)) {
 131                         be_add_reload(spill_env, node, use, cls, 1);
 132                 }
 133         }
 134
 135         bitset_set(env->spilled_nodes, get_irn_idx(node));
 136 }
 137
 138 /**
 139  * spill @p n nodes from a nodeset. Removes the nodes from the nodeset and
 140  * sets the spilled bits in env->spilled_nodes.
 141  */
 142 static
 143 void do_spilling(daemel_env_t *env, ir_nodeset_t *live_nodes, ir_node *node)
 144 {
 145         size_t                       node_count      = ir_nodeset_size(live_nodes);
 146         size_t                       additional_defines = 0;
 147         size_t                       reload_values      = 0;
 148         int                          registers          = env->n_regs;
 149         const arch_env_t            *arch_env           = env->arch_env;
 150         const arch_register_class_t *cls                = env->cls;
 151         spill_candidate_t           *candidates;
 152         ir_nodeset_iterator_t        iter;
 153         size_t                       i, arity;
 154         int                          spills_needed;
 155         size_t                       cand_idx;
 156         ir_node                     *n;
 157         const bitset_t              *spilled_nodes = env->spilled_nodes;
 158
 159         /* mode_T nodes define several values at once. Count them */
 160         if(get_irn_mode(node) == mode_T) {
 161                 const ir_edge_t *edge;
 162
 163                 foreach_out_edge(node, edge) {
 164                         const ir_node *proj = get_edge_src_irn(edge);
 165
 166                         if(arch_irn_consider_in_reg_alloc(arch_env, cls, proj)) {
 167                                 ++additional_defines;
 168                         }
 169                 }
 170         }
 171         if(bitset_is_set(spilled_nodes, get_irn_idx(node)))
 172                 ++additional_defines;
 173
 174         /* we need registers for the non-live argument values */
 175         arity = get_irn_arity(node);
 176         for(i = 0; i < arity; ++i) {
 177                 ir_node *pred = get_irn_n(node, i);
 178                 if(arch_irn_consider_in_reg_alloc(arch_env, cls, pred)
 179                                 && !ir_nodeset_contains(live_nodes, pred)) {
 180                         ++reload_values;
 181                 }
 182         }
 183
 184         if(reload_values > additional_defines)
 185                 additional_defines = reload_values;
 186
 187         spills_needed = (node_count + additional_defines) - registers;
 188         if(spills_needed <= 0)
 189                 return;
 190         DBG((dbg, LEVEL_2, "\tspills needed after %+F: %d\n", node, spills_needed));
 191
 192         candidates = xmalloc(node_count * sizeof(candidates[0]));
 193
 194         /* construct array with spill candidates and calculate their costs */
 195         i = 0;
 196         foreach_ir_nodeset(live_nodes, n, iter) {
 197                 spill_candidate_t *candidate = & candidates[i];
 198
 199                 assert(!bitset_is_set(spilled_nodes, get_irn_idx(n)));
 200
 201                 candidate->node  = n;
 202                 candidate->costs = get_spill_costs(env, n);
 203                 ++i;
 204         }
 205         assert(i == node_count);
 206
 207         /* sort spill candidates */
 208         qsort(candidates, node_count, sizeof(candidates[0]),
 209               compare_spill_candidates_desc);
 210
 211         /* spill cheapest ones */
 212         cand_idx = 0;
 213         while(spills_needed > 0) {
 214                 spill_candidate_t *candidate;
 215                 ir_node           *cand_node;
 216                 int               is_use;
 217
 218                 if (cand_idx >= node_count) {
 219                         panic("can't spill enough values for node %+F\n", node);
 220                 }
 221
 222
 223                 candidate = &candidates[cand_idx];
 224                 cand_node = candidate->node;
 225                 ++cand_idx;
 226
 227                 if(arch_irn_is(arch_env, cand_node, dont_spill))
 228                         continue;
 229
 230                 /* make sure the node is not an argument of the instruction */
 231                 is_use = 0;
 232                 for (i = 0; i < arity; ++i) {
 233                         ir_node *in = get_irn_n(node, i);
 234                         if(in == cand_node) {
 235                                 is_use = 1;
 236                                 break;
 237                         }
 238                 }
 239                 if(is_use) {
 240                         continue;
 241                 }
 242
 243                 spill_node(env, cand_node);
 244                 ir_nodeset_remove(live_nodes, cand_node);
 245                 --spills_needed;
 246         }
 247
 248         free(candidates);
 249 }
 250
 251 /**
 252  * similar to be_liveness_transfer.
 253  * custom liveness transfer function, that doesn't place already spilled values
 254  * into the liveness set
 255  */
 256 static
 257 void liveness_transfer_remove_defs(daemel_env_t *env, ir_node *node,
 258                                    ir_nodeset_t *nodeset)
 259 {
 260         const arch_register_class_t *cls      = env->cls;
 261         const arch_env_t            *arch_env = env->arch_env;
 262
 263         /* You should better break out of your loop when hitting the first phi
 264          * function. */
 265         assert(!is_Phi(node) && "liveness_transfer produces invalid results for phi nodes");
 266
 267         if (get_irn_mode(node) == mode_T) {
 268                 const ir_edge_t *edge;
 269
 270                 foreach_out_edge(node, edge) {
 271                         const ir_node *proj = get_edge_src_irn(edge);
 272
 273                         if (arch_irn_consider_in_reg_alloc(arch_env, cls, proj)) {
 274                                 ir_nodeset_remove(nodeset, proj);
 275                         }
 276                 }
 277         }
 278
 279     if(arch_irn_consider_in_reg_alloc(arch_env, cls, node)) {
 280         ir_nodeset_remove(nodeset, node);
 281     }
 282 }
 283
 284 static void liveness_transfer_add_uses(daemel_env_t *env, ir_node *node,
 285                                    ir_nodeset_t *nodeset)
 286 {
 287         int i, arity;
 288         const arch_register_class_t *cls      = env->cls;
 289         const arch_env_t            *arch_env = env->arch_env;
 290         const bitset_t              *bitset   = env->spilled_nodes;
 291
 292
 293     arity = get_irn_arity(node);
 294     for(i = 0; i < arity; ++i) {
 295         ir_node *op = get_irn_n(node, i);
 296
 297         if(arch_irn_consider_in_reg_alloc(arch_env, cls, op)
 298                    && !bitset_is_set(bitset, get_irn_idx(op))) {
 299             ir_nodeset_insert(nodeset, op);
 300                 }
 301     }
 302 }
 303
 304 static __attribute__((unused))
 305 void print_nodeset(ir_nodeset_t *nodeset)
 306 {
 307         ir_nodeset_iterator_t  iter;
 308         ir_node               *node;
 309
 310         foreach_ir_nodeset(nodeset, node, iter) {
 311                 ir_fprintf(stderr, "%+F ", node);
 312         }
 313         fprintf(stderr, "\n");
 314 }
 315
 316 /**
 317  * make sure register pressure in a block is always equal or below the number
 318  * of available registers
 319  */
 320 static
 321 void spill_block(ir_node *block, void *data)
 322 {
 323         daemel_env_t                *env           = data;
 324         const arch_env_t            *arch_env      = env->arch_env;
 325         const arch_register_class_t *cls           = env->cls;
 326         const be_lv_t               *lv            = env->lv;
 327         ir_nodeset_t                 live_nodes;
 328         ir_nodeset_iterator_t        iter;
 329         ir_node                     *node;
 330         bitset_t                    *spilled_nodes = env->spilled_nodes;
 331         int                          phi_count, spilled_phis, regpressure, phi_spills_needed;
 332
 333         DBG((dbg, LEVEL_1, "spilling block %+F\n", block));
 334
 335         ir_nodeset_init(&live_nodes);
 336         be_liveness_end_of_block(lv, arch_env, cls, block, &live_nodes);
 337
 338         foreach_ir_nodeset(&live_nodes, node, iter) {
 339                 DBG((dbg, LEVEL_2, "\t%+F is live-end... ", node));
 340                 if(bitset_is_set(spilled_nodes, get_irn_idx(node))) {
 341                         DBG((dbg, LEVEL_2, "but spilled; removing.\n"));
 342                         ir_nodeset_remove_iterator(&live_nodes, &iter);
 343                 } else {
 344                         DBG((dbg, LEVEL_2, "keeping.\n"));
 345                 }
 346         }
 347
 348         sched_foreach_reverse(block, node) {
 349                 if(is_Phi(node))
 350                         break;
 351
 352                 if(be_is_Keep(node)) {
 353                         /* remove defs should never do something for keep nodes, but we
 354                          * leave it here for consistency */
 355                         liveness_transfer_remove_defs(env, node, &live_nodes);
 356                         liveness_transfer_add_uses(env, node, &live_nodes);
 357                         continue;
 358                 }
 359
 360                 liveness_transfer_remove_defs(env, node, &live_nodes);
 361                 do_spilling(env, &live_nodes, node);
 362                 liveness_transfer_add_uses(env, node, &live_nodes);
 363         }
 364
 365         phi_count = 0;
 366         spilled_phis = 0;
 367         sched_foreach(block, node) {
 368                 if(!is_Phi(node))
 369                         break;
 370
 371                 ++phi_count;
 372                 if(bitset_is_set(spilled_nodes, get_irn_idx(node))) {
 373                         ++spilled_phis;
 374                 }
 375         }
 376         regpressure       = ir_nodeset_size(&live_nodes) + spilled_phis;
 377         phi_spills_needed = regpressure - env->n_regs;
 378         DBG((dbg, LEVEL_3, "Regpressure before phis: %d phispills: %d\n",
 379              regpressure, phi_spills_needed));
 380         sched_foreach(block, node) {
 381                 if(!is_Phi(node))
 382                         break;
 383                 if(phi_spills_needed <= 0)
 384                         break;
 385
 386                 if(bitset_is_set(spilled_nodes, get_irn_idx(node))) {
 387                         be_spill_phi(env->spill_env, node);
 388                         --phi_spills_needed;
 389                 }
 390         }
 391         assert(phi_spills_needed <= 0);
 392
 393         ir_nodeset_destroy(&live_nodes);
 394 }
 395
 396 void be_spill_daemel(be_irg_t *birg, const arch_register_class_t *cls)
 397 {
 398         daemel_env_t  env;
 399         ir_graph     *irg    = be_get_birg_irg(birg);
 400         int           n_regs = cls->n_regs - be_put_ignore_regs(birg, cls, NULL);
 401
 402         if(n_regs == 0)
 403                 return;
 404
 405         be_liveness_assure_sets(be_assure_liveness(birg));
 406
 407         env.spill_env     = be_new_spill_env(birg);
 408         env.n_regs        = n_regs;
 409         env.arch_env      = be_get_birg_arch_env(birg);
 410         env.cls           = cls;
 411         env.lv            = be_get_birg_liveness(birg);
 412         env.spilled_nodes = bitset_malloc(get_irg_last_idx(irg));
 413
 414         DBG((dbg, LEVEL_1, "*** RegClass %s\n", cls->name));
 415
 416         irg_block_walk_graph(irg, spill_block, NULL, &env);
 417
 418         bitset_free(env.spilled_nodes);
 419
 420         be_insert_spills_reloads(env.spill_env);
 421
 422         be_delete_spill_env(env.spill_env);
 423 }
 424
 425 void be_init_daemelspill(void)
 426 {
 427         static be_spiller_t daemel_spiller = {
 428                 be_spill_daemel
 429         };
 430
 431         be_register_spiller("daemel", &daemel_spiller);
 432         FIRM_DBG_REGISTER(dbg, "ir.be.spilldaemel");
 433 }
 434
 435 BE_REGISTER_MODULE_CONSTRUCTOR(be_init_doedelspill);