nsz Git - libfirm/blob - ir/opt/ldstopt.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   Load/Store optimizations.
  23  * @author  Michael Beck
  24  * @version $Id$
  25  */
  26 #ifdef HAVE_CONFIG_H
  27 # include "config.h"
  28 #endif
  29
  30 #include <string.h>
  31
  32 #include "iroptimize.h"
  33 #include "irnode_t.h"
  34 #include "irgraph_t.h"
  35 #include "irmode_t.h"
  36 #include "iropt_t.h"
  37 #include "ircons_t.h"
  38 #include "irgmod.h"
  39 #include "irgwalk.h"
  40 #include "irvrfy.h"
  41 #include "tv_t.h"
  42 #include "dbginfo_t.h"
  43 #include "iropt_dbg.h"
  44 #include "irflag_t.h"
  45 #include "array.h"
  46 #include "irhooks.h"
  47 #include "iredges.h"
  48 #include "irtools.h"
  49 #include "opt_polymorphy.h"
  50 #include "irmemory.h"
  51 #include "xmalloc.h"
  52 #include "irphase_t.h"
  53 #include "irgopt.h"
  54 #include "debug.h"
  55
  56 /** The debug handle. */
  57 DEBUG_ONLY(static firm_dbg_module_t *dbg;)
  58
  59 #ifdef DO_CACHEOPT
  60 #include "cacheopt/cachesim.h"
  61 #endif
  62
  63 #undef IMAX
  64 #define IMAX(a,b)       ((a) > (b) ? (a) : (b))
  65
  66 #define MAX_PROJ        IMAX(IMAX(pn_Load_max, pn_Store_max), pn_Call_max)
  67
  68 enum changes_t {
  69         DF_CHANGED = 1,       /**< data flow changed */
  70         CF_CHANGED = 2,       /**< control flow changed */
  71 };
  72
  73 /**
  74  * walker environment
  75  */
  76 typedef struct _walk_env_t {
  77         struct obstack obst;          /**< list of all stores */
  78         unsigned changes;             /**< a bitmask of graph changes */
  79 } walk_env_t;
  80
  81 /** A Load/Store info. */
  82 typedef struct _ldst_info_t {
  83         ir_node  *projs[MAX_PROJ];    /**< list of Proj's of this node */
  84         ir_node  *exc_block;          /**< the exception block if available */
  85         int      exc_idx;             /**< predecessor index in the exception block */
  86         unsigned visited;             /**< visited counter for breaking loops */
  87 } ldst_info_t;
  88
  89 /**
  90  * flags for control flow.
  91  */
  92 enum block_flags_t {
  93         BLOCK_HAS_COND = 1,      /**< Block has conditional control flow */
  94         BLOCK_HAS_EXC  = 2       /**< Block has exceptional control flow */
  95 };
  96
  97 /**
  98  * a Block info.
  99  */
 100 typedef struct _block_info_t {
 101         unsigned flags;               /**< flags for the block */
 102 } block_info_t;
 103
 104 /** the master visited flag for loop detection. */
 105 static unsigned master_visited = 0;
 106
 107 #define INC_MASTER()       ++master_visited
 108 #define MARK_NODE(info)    (info)->visited = master_visited
 109 #define NODE_VISITED(info) (info)->visited >= master_visited
 110
 111 /**
 112  * get the Load/Store info of a node
 113  */
 114 static ldst_info_t *get_ldst_info(ir_node *node, struct obstack *obst) {
 115         ldst_info_t *info = get_irn_link(node);
 116
 117         if (! info) {
 118                 info = obstack_alloc(obst, sizeof(*info));
 119                 memset(info, 0, sizeof(*info));
 120                 set_irn_link(node, info);
 121         }
 122         return info;
 123 }  /* get_ldst_info */
 124
 125 /**
 126  * get the Block info of a node
 127  */
 128 static block_info_t *get_block_info(ir_node *node, struct obstack *obst) {
 129         block_info_t *info = get_irn_link(node);
 130
 131         if (! info) {
 132                 info = obstack_alloc(obst, sizeof(*info));
 133                 memset(info, 0, sizeof(*info));
 134                 set_irn_link(node, info);
 135         }
 136         return info;
 137 }  /* get_block_info */
 138
 139 /**
 140  * update the projection info for a Load/Store
 141  */
 142 static unsigned update_projs(ldst_info_t *info, ir_node *proj)
 143 {
 144         long nr = get_Proj_proj(proj);
 145
 146         assert(0 <= nr && nr <= MAX_PROJ && "Wrong proj from LoadStore");
 147
 148         if (info->projs[nr]) {
 149                 /* there is already one, do CSE */
 150                 exchange(proj, info->projs[nr]);
 151                 return DF_CHANGED;
 152         }
 153         else {
 154                 info->projs[nr] = proj;
 155                 return 0;
 156         }
 157 }  /* update_projs */
 158
 159 /**
 160  * update the exception block info for a Load/Store node.
 161  *
 162  * @param info   the load/store info struct
 163  * @param block  the exception handler block for this load/store
 164  * @param pos    the control flow input of the block
 165  */
 166 static unsigned update_exc(ldst_info_t *info, ir_node *block, int pos)
 167 {
 168         assert(info->exc_block == NULL && "more than one exception block found");
 169
 170         info->exc_block = block;
 171         info->exc_idx   = pos;
 172         return 0;
 173 }  /* update_exc */
 174
 175 /** Return the number of uses of an address node */
 176 #define get_irn_n_uses(adr)     get_irn_n_edges(adr)
 177
 178 /**
 179  * walker, collects all Load/Store/Proj nodes
 180  *
 181  * walks from Start -> End
 182  */
 183 static void collect_nodes(ir_node *node, void *env)
 184 {
 185         ir_opcode   opcode = get_irn_opcode(node);
 186         ir_node     *pred, *blk, *pred_blk;
 187         ldst_info_t *ldst_info;
 188         walk_env_t  *wenv = env;
 189
 190         if (opcode == iro_Proj) {
 191                 pred   = get_Proj_pred(node);
 192                 opcode = get_irn_opcode(pred);
 193
 194                 if (opcode == iro_Load || opcode == iro_Store || opcode == iro_Call) {
 195                         ldst_info = get_ldst_info(pred, &wenv->obst);
 196
 197                         wenv->changes |= update_projs(ldst_info, node);
 198
 199                         /*
 200                          * Place the Proj's to the same block as the
 201                          * predecessor Load. This is always ok and prevents
 202                          * "non-SSA" form after optimizations if the Proj
 203                          * is in a wrong block.
 204                          */
 205                         blk      = get_nodes_block(node);
 206                         pred_blk = get_nodes_block(pred);
 207                         if (blk != pred_blk) {
 208                                 wenv->changes |= DF_CHANGED;
 209                                 set_nodes_block(node, pred_blk);
 210                         }
 211                 }
 212         } else if (opcode == iro_Block) {
 213                 int i;
 214
 215                 for (i = get_Block_n_cfgpreds(node) - 1; i >= 0; --i) {
 216                         ir_node      *pred_block, *proj;
 217                         block_info_t *bl_info;
 218                         int          is_exc = 0;
 219
 220                         pred = proj = get_Block_cfgpred(node, i);
 221
 222                         if (is_Proj(proj)) {
 223                                 pred   = get_Proj_pred(proj);
 224                                 is_exc = get_Proj_proj(proj) == pn_Generic_X_except;
 225                         }
 226
 227                         /* ignore Bad predecessors, they will be removed later */
 228                         if (is_Bad(pred))
 229                                 continue;
 230
 231                         pred_block = get_nodes_block(pred);
 232                         bl_info    = get_block_info(pred_block, &wenv->obst);
 233
 234                         if (is_fragile_op(pred) && is_exc)
 235                                 bl_info->flags |= BLOCK_HAS_EXC;
 236                         else if (is_irn_forking(pred))
 237                                 bl_info->flags |= BLOCK_HAS_COND;
 238
 239                         opcode = get_irn_opcode(pred);
 240                         if (is_exc && (opcode == iro_Load || opcode == iro_Store || opcode == iro_Call)) {
 241                                 ldst_info = get_ldst_info(pred, &wenv->obst);
 242
 243                                 wenv->changes |= update_exc(ldst_info, node, i);
 244                         }
 245                 }
 246         }
 247 }  /* collect_nodes */
 248
 249 /**
 250  * Returns an entity if the address ptr points to a constant one.
 251  *
 252  * @param ptr  the address
 253  *
 254  * @return an entity or NULL
 255  */
 256 static ir_entity *find_constant_entity(ir_node *ptr)
 257 {
 258         for (;;) {
 259                 if (is_SymConst(ptr) && get_SymConst_kind(ptr) == symconst_addr_ent) {
 260                         ir_entity *ent = get_SymConst_entity(ptr);
 261                         if (variability_constant == get_entity_variability(ent))
 262                                 return ent;
 263                         return NULL;
 264                 } else if (is_Sel(ptr)) {
 265                         ir_entity *ent = get_Sel_entity(ptr);
 266                         ir_type   *tp  = get_entity_owner(ent);
 267
 268                         /* Do not fiddle with polymorphism. */
 269                         if (is_Class_type(get_entity_owner(ent)) &&
 270                                 ((get_entity_n_overwrites(ent)    != 0) ||
 271                                 (get_entity_n_overwrittenby(ent) != 0)   ) )
 272                                 return NULL;
 273
 274                         if (is_Array_type(tp)) {
 275                                 /* check bounds */
 276                                 int i, n;
 277
 278                                 for (i = 0, n = get_Sel_n_indexs(ptr); i < n; ++i) {
 279                                         ir_node *bound;
 280                                         tarval *tlower, *tupper;
 281                                         ir_node *index = get_Sel_index(ptr, i);
 282                                         tarval *tv     = computed_value(index);
 283
 284                                         /* check if the index is constant */
 285                                         if (tv == tarval_bad)
 286                                                 return NULL;
 287
 288                                         bound  = get_array_lower_bound(tp, i);
 289                                         tlower = computed_value(bound);
 290                                         bound  = get_array_upper_bound(tp, i);
 291                                         tupper = computed_value(bound);
 292
 293                                         if (tlower == tarval_bad || tupper == tarval_bad)
 294                                                 return NULL;
 295
 296                                         if (tarval_cmp(tv, tlower) & pn_Cmp_Lt)
 297                                                 return NULL;
 298                                         if (tarval_cmp(tupper, tv) & pn_Cmp_Lt)
 299                                                 return NULL;
 300
 301                                         /* ok, bounds check finished */
 302                                 }
 303                         }
 304
 305                         if (variability_constant == get_entity_variability(ent))
 306                                 return ent;
 307
 308                         /* try next */
 309                         ptr = get_Sel_ptr(ptr);
 310                 } else if (is_Add(ptr)) {
 311                         ir_node *l = get_Add_left(ptr);
 312                         ir_node *r = get_Add_right(ptr);
 313
 314                         if (get_irn_mode(l) == get_irn_mode(ptr) && is_Const(r))
 315                                 ptr = l;
 316                         else if (get_irn_mode(r) == get_irn_mode(ptr) && is_Const(l))
 317                                 ptr = r;
 318                         else
 319                                 return NULL;
 320
 321                         /* for now, we support only one addition, reassoc should fold all others */
 322                         if (! is_SymConst(ptr) && !is_Sel(ptr))
 323                                 return NULL;
 324                 } else if (is_Sub(ptr)) {
 325                         ir_node *l = get_Sub_left(ptr);
 326                         ir_node *r = get_Sub_right(ptr);
 327
 328                         if (get_irn_mode(l) == get_irn_mode(ptr) &&     is_Const(r))
 329                                 ptr = l;
 330                         else
 331                                 return NULL;
 332                         /* for now, we support only one substraction, reassoc should fold all others */
 333                         if (! is_SymConst(ptr) && !is_Sel(ptr))
 334                                 return NULL;
 335                 } else
 336                         return NULL;
 337         }
 338 }  /* find_constant_entity */
 339
 340 /**
 341  * Return the Selection index of a Sel node from dimension n
 342  */
 343 static long get_Sel_array_index_long(ir_node *n, int dim) {
 344         ir_node *index = get_Sel_index(n, dim);
 345         assert(is_Const(index));
 346         return get_tarval_long(get_Const_tarval(index));
 347 }  /* get_Sel_array_index_long */
 348
 349 /**
 350  * Returns the accessed component graph path for an
 351  * node computing an address.
 352  *
 353  * @param ptr    the node computing the address
 354  * @param depth  current depth in steps upward from the root
 355  *               of the address
 356  */
 357 static compound_graph_path *rec_get_accessed_path(ir_node *ptr, int depth) {
 358         compound_graph_path *res = NULL;
 359         ir_entity           *root, *field, *ent;
 360         int                 path_len, pos, idx;
 361         tarval              *tv;
 362         ir_type             *tp;
 363
 364         if (is_SymConst(ptr)) {
 365                 /* a SymConst. If the depth is 0, this is an access to a global
 366                  * entity and we don't need a component path, else we know
 367                  * at least it's length.
 368                  */
 369                 assert(get_SymConst_kind(ptr) == symconst_addr_ent);
 370                 root = get_SymConst_entity(ptr);
 371                 res = (depth == 0) ? NULL : new_compound_graph_path(get_entity_type(root), depth);
 372         } else if (is_Sel(ptr)) {
 373                 /* it's a Sel, go up until we find the root */
 374                 res = rec_get_accessed_path(get_Sel_ptr(ptr), depth+1);
 375                 if (res == NULL)
 376                         return NULL;
 377
 378                 /* fill up the step in the path at the current position */
 379                 field    = get_Sel_entity(ptr);
 380                 path_len = get_compound_graph_path_length(res);
 381                 pos      = path_len - depth - 1;
 382                 set_compound_graph_path_node(res, pos, field);
 383
 384                 if (is_Array_type(get_entity_owner(field))) {
 385                         assert(get_Sel_n_indexs(ptr) == 1 && "multi dim arrays not implemented");
 386                         set_compound_graph_path_array_index(res, pos, get_Sel_array_index_long(ptr, 0));
 387                 }
 388         } else if (is_Add(ptr)) {
 389                 ir_node *l = get_Add_left(ptr);
 390                 ir_node *r = get_Add_right(ptr);
 391                 ir_mode *mode;
 392
 393                 if (is_Const(r)) {
 394                         ptr = l;
 395                         tv  = get_Const_tarval(r);
 396                 } else {
 397                         ptr = r;
 398                         tv  = get_Const_tarval(l);
 399                 }
 400 ptr_arith:
 401                 mode = get_tarval_mode(tv);
 402
 403                 /* ptr must be a Sel or a SymConst, this was checked in find_constant_entity() */
 404                 if (is_Sel(ptr)) {
 405                         field = get_Sel_entity(ptr);
 406                 } else {
 407                         field = get_SymConst_entity(ptr);
 408                 }
 409                 idx = 0;
 410                 for (ent = field;;) {
 411                         unsigned size;
 412                         tarval   *sz, *tv_index, *tlower, *tupper;
 413                         long     index;
 414                         ir_node  *bound;
 415
 416                         tp = get_entity_type(ent);
 417                         if (! is_Array_type(tp))
 418                                 break;
 419                         ent = get_array_element_entity(tp);
 420                         size = get_type_size_bytes(get_entity_type(ent));
 421                         sz   = new_tarval_from_long(size, mode);
 422
 423                         tv_index = tarval_div(tv, sz);
 424                         tv       = tarval_mod(tv, sz);
 425
 426                         if (tv_index == tarval_bad || tv == tarval_bad)
 427                                 return NULL;
 428
 429                         assert(get_array_n_dimensions(tp) == 1 && "multiarrays not implemented");
 430                         bound  = get_array_lower_bound(tp, 0);
 431                         tlower = computed_value(bound);
 432                         bound  = get_array_upper_bound(tp, 0);
 433                         tupper = computed_value(bound);
 434
 435                         if (tlower == tarval_bad || tupper == tarval_bad)
 436                                 return NULL;
 437
 438                         if (tarval_cmp(tv_index, tlower) & pn_Cmp_Lt)
 439                                 return NULL;
 440                         if (tarval_cmp(tupper, tv_index) & pn_Cmp_Lt)
 441                                 return NULL;
 442
 443                         /* ok, bounds check finished */
 444                         index = get_tarval_long(tv_index);
 445                         ++idx;
 446                 }
 447                 if (! tarval_is_null(tv)) {
 448                         /* access to some struct/union member */
 449                         return NULL;
 450                 }
 451
 452                 /* should be at least ONE array */
 453                 if (idx == 0)
 454                         return NULL;
 455
 456                 res = rec_get_accessed_path(ptr, depth + idx);
 457                 if (res == NULL)
 458                         return NULL;
 459
 460                 path_len = get_compound_graph_path_length(res);
 461                 pos      = path_len - depth - idx;
 462
 463                 for (ent = field;;) {
 464                         unsigned size;
 465                         tarval   *sz, *tv_index;
 466                         long     index;
 467
 468                         tp = get_entity_type(ent);
 469                         if (! is_Array_type(tp))
 470                                 break;
 471                         ent = get_array_element_entity(tp);
 472                         set_compound_graph_path_node(res, pos, ent);
 473
 474                         size = get_type_size_bytes(get_entity_type(ent));
 475                         sz   = new_tarval_from_long(size, mode);
 476
 477                         tv_index = tarval_div(tv, sz);
 478                         tv       = tarval_mod(tv, sz);
 479
 480                         /* worked above, should work again */
 481                         assert(tv_index != tarval_bad && tv != tarval_bad);
 482
 483                         /* bounds already checked above */
 484                         index = get_tarval_long(tv_index);
 485                         set_compound_graph_path_array_index(res, pos, index);
 486                         ++pos;
 487                 }
 488         } else if (is_Sub(ptr)) {
 489                 ir_node *l = get_Sub_left(ptr);
 490                 ir_node *r = get_Sub_right(ptr);
 491
 492                 ptr = l;
 493                 tv  = get_Const_tarval(r);
 494                 tv  = tarval_neg(tv);
 495                 goto ptr_arith;
 496         }
 497         return res;
 498 }  /* rec_get_accessed_path */
 499
 500 /**
 501  * Returns an access path or NULL.  The access path is only
 502  * valid, if the graph is in phase_high and _no_ address computation is used.
 503  */
 504 static compound_graph_path *get_accessed_path(ir_node *ptr) {
 505         return rec_get_accessed_path(ptr, 0);
 506 }  /* get_accessed_path */
 507
 508 typedef struct path_entry {
 509         ir_entity         *ent;
 510         struct path_entry *next;
 511         long              index;
 512 } path_entry;
 513
 514 static ir_node *rec_find_compound_ent_value(ir_node *ptr, path_entry *next) {
 515         path_entry       entry, *p;
 516         ir_entity        *ent, *field;
 517         ir_initializer_t *initializer;
 518         tarval           *tv;
 519         ir_type          *tp;
 520         unsigned         n;
 521
 522         entry.next = next;
 523         if (is_SymConst(ptr)) {
 524                 /* found the root */
 525                 ent         = get_SymConst_entity(ptr);
 526                 initializer = get_entity_initializer(ent);
 527                 for (p = next; p != NULL;) {
 528                         if (initializer->kind != IR_INITIALIZER_COMPOUND)
 529                                 return NULL;
 530                         n  = get_initializer_compound_n_entries(initializer);
 531                         tp = get_entity_type(ent);
 532
 533                         if (is_Array_type(tp)) {
 534                                 ent = get_array_element_entity(tp);
 535                                 if (ent != p->ent) {
 536                                         /* a missing [0] */
 537                                         if (0 >= n)
 538                                                 return NULL;
 539                                         initializer = get_initializer_compound_value(initializer, 0);
 540                                         continue;
 541                                 }
 542                         }
 543                         if (p->index >= n)
 544                                 return NULL;
 545                         initializer = get_initializer_compound_value(initializer, p->index);
 546
 547                         ent = p->ent;
 548                         p   = p->next;
 549                 }
 550                 tp = get_entity_type(ent);
 551                 while (is_Array_type(tp)) {
 552                         ent = get_array_element_entity(tp);
 553                         tp = get_entity_type(ent);
 554                         /* a missing [0] */
 555                         n  = get_initializer_compound_n_entries(initializer);
 556                         if (0 >= n)
 557                                 return NULL;
 558                         initializer = get_initializer_compound_value(initializer, 0);
 559                 }
 560
 561                 switch (initializer->kind) {
 562                 case IR_INITIALIZER_CONST:
 563                         return get_initializer_const_value(initializer);
 564                 case IR_INITIALIZER_TARVAL:
 565                 case IR_INITIALIZER_NULL:
 566                 default:
 567                         return NULL;
 568                 }
 569         } else if (is_Sel(ptr)) {
 570                 entry.ent = field = get_Sel_entity(ptr);
 571                 tp = get_entity_owner(field);
 572                 if (is_Array_type(tp)) {
 573                         assert(get_Sel_n_indexs(ptr) == 1 && "multi dim arrays not implemented");
 574                         entry.index = get_Sel_array_index_long(ptr, 0) - get_array_lower_bound_int(tp, 0);
 575                 } else {
 576                         int i, n_members = get_compound_n_members(tp);
 577                         for (i = 0; i < n_members; ++i) {
 578                                 if (get_compound_member(tp, i) == field)
 579                                         break;
 580                         }
 581                         if (i >= n_members) {
 582                                 /* not found: should NOT happen */
 583                                 return NULL;
 584                         }
 585                         entry.index = i;
 586                 }
 587                 return rec_find_compound_ent_value(get_Sel_ptr(ptr), &entry);
 588         }  else if (is_Add(ptr)) {
 589                 ir_node  *l = get_Add_left(ptr);
 590                 ir_node  *r = get_Add_right(ptr);
 591                 ir_mode  *mode;
 592                 unsigned pos;
 593
 594                 if (is_Const(r)) {
 595                         ptr = l;
 596                         tv  = get_Const_tarval(r);
 597                 } else {
 598                         ptr = r;
 599                         tv  = get_Const_tarval(l);
 600                 }
 601 ptr_arith:
 602                 mode = get_tarval_mode(tv);
 603
 604                 /* ptr must be a Sel or a SymConst, this was checked in find_constant_entity() */
 605                 if (is_Sel(ptr)) {
 606                         field = get_Sel_entity(ptr);
 607                 } else {
 608                         field = get_SymConst_entity(ptr);
 609                 }
 610
 611                 /* count needed entries */
 612                 pos = 0;
 613                 for (ent = field;;) {
 614                         tp = get_entity_type(ent);
 615                         if (! is_Array_type(tp))
 616                                 break;
 617                         ent = get_array_element_entity(tp);
 618                         ++pos;
 619                 }
 620                 /* should be at least ONE entry */
 621                 if (pos == 0)
 622                         return NULL;
 623
 624                 /* allocate the right number of entries */
 625                 NEW_ARR_A(path_entry, p, pos);
 626
 627                 /* fill them up */
 628                 pos = 0;
 629                 for (ent = field;;) {
 630                         unsigned size;
 631                         tarval   *sz, *tv_index, *tlower, *tupper;
 632                         long     index;
 633                         ir_node  *bound;
 634
 635                         tp = get_entity_type(ent);
 636                         if (! is_Array_type(tp))
 637                                 break;
 638                         ent = get_array_element_entity(tp);
 639                         p[pos].ent  = ent;
 640                         p[pos].next = &p[pos + 1];
 641
 642                         size = get_type_size_bytes(get_entity_type(ent));
 643                         sz   = new_tarval_from_long(size, mode);
 644
 645                         tv_index = tarval_div(tv, sz);
 646                         tv       = tarval_mod(tv, sz);
 647
 648                         if (tv_index == tarval_bad || tv == tarval_bad)
 649                                 return NULL;
 650
 651                         assert(get_array_n_dimensions(tp) == 1 && "multiarrays not implemented");
 652                         bound  = get_array_lower_bound(tp, 0);
 653                         tlower = computed_value(bound);
 654                         bound  = get_array_upper_bound(tp, 0);
 655                         tupper = computed_value(bound);
 656
 657                         if (tlower == tarval_bad || tupper == tarval_bad)
 658                                 return NULL;
 659
 660                         if (tarval_cmp(tv_index, tlower) & pn_Cmp_Lt)
 661                                 return NULL;
 662                         if (tarval_cmp(tupper, tv_index) & pn_Cmp_Lt)
 663                                 return NULL;
 664
 665                         /* ok, bounds check finished */
 666                         index = get_tarval_long(tv_index);
 667                         p[pos].index = index;
 668                         ++pos;
 669                 }
 670                 if (! tarval_is_null(tv)) {
 671                         /* hmm, wrong access */
 672                         return NULL;
 673                 }
 674                 p[pos - 1].next = next;
 675                 return rec_find_compound_ent_value(ptr, p);
 676         } else if (is_Sub(ptr)) {
 677                 ir_node *l = get_Sub_left(ptr);
 678                 ir_node *r = get_Sub_right(ptr);
 679
 680                 ptr = l;
 681                 tv  = get_Const_tarval(r);
 682                 tv  = tarval_neg(tv);
 683                 goto ptr_arith;
 684         }
 685         return NULL;
 686 }
 687
 688 static ir_node *find_compound_ent_value(ir_node *ptr) {
 689         return rec_find_compound_ent_value(ptr, NULL);
 690 }
 691
 692 /* forward */
 693 static void reduce_adr_usage(ir_node *ptr);
 694
 695 /**
 696  * Update a Load that may lost it's usage.
 697  */
 698 static void handle_load_update(ir_node *load) {
 699         ldst_info_t *info = get_irn_link(load);
 700
 701         /* do NOT touch volatile loads for now */
 702         if (get_Load_volatility(load) == volatility_is_volatile)
 703                 return;
 704
 705         if (! info->projs[pn_Load_res] && ! info->projs[pn_Load_X_except]) {
 706                 ir_node *ptr = get_Load_ptr(load);
 707                 ir_node *mem = get_Load_mem(load);
 708
 709                 /* a Load which value is neither used nor exception checked, remove it */
 710                 exchange(info->projs[pn_Load_M], mem);
 711                 if (info->projs[pn_Load_X_regular])
 712                         exchange(info->projs[pn_Load_X_regular], new_r_Jmp(current_ir_graph, get_nodes_block(load)));
 713                 kill_node(load);
 714                 reduce_adr_usage(ptr);
 715         }
 716 }  /* handle_load_update */
 717
 718 /**
 719  * A Use of an address node is vanished. Check if this was a Proj
 720  * node and update the counters.
 721  */
 722 static void reduce_adr_usage(ir_node *ptr) {
 723         if (is_Proj(ptr)) {
 724                 if (get_irn_n_edges(ptr) <= 0) {
 725                         /* this Proj is dead now */
 726                         ir_node *pred = get_Proj_pred(ptr);
 727
 728                         if (is_Load(pred)) {
 729                                 ldst_info_t *info = get_irn_link(pred);
 730                                 info->projs[get_Proj_proj(ptr)] = NULL;
 731
 732                                 /* this node lost it's result proj, handle that */
 733                                 handle_load_update(pred);
 734                         }
 735                 }
 736         }
 737 }  /* reduce_adr_usage */
 738
 739 /**
 740  * Check, if an already existing value of mode old_mode can be converted
 741  * into the needed one new_mode without loss.
 742  */
 743 static int can_use_stored_value(ir_mode *old_mode, ir_mode *new_mode) {
 744         if (old_mode == new_mode)
 745                 return 1;
 746
 747         /* if both modes are two-complement ones, we can always convert the
 748            Stored value into the needed one. */
 749         if (get_mode_size_bits(old_mode) >= get_mode_size_bits(new_mode) &&
 750                   get_mode_arithmetic(old_mode) == irma_twos_complement &&
 751                   get_mode_arithmetic(new_mode) == irma_twos_complement)
 752                 return 1;
 753         return 0;
 754 }  /* can_use_stored_value */
 755
 756 /**
 757  * Check whether a Call is at least pure, ie. does only read memory.
 758  */
 759 static unsigned is_Call_pure(ir_node *call) {
 760         ir_type *call_tp = get_Call_type(call);
 761         unsigned prop = get_method_additional_properties(call_tp);
 762
 763         /* check first the call type */
 764         if ((prop & (mtp_property_const|mtp_property_pure)) == 0) {
 765                 /* try the called entity */
 766                 ir_node *ptr = get_Call_ptr(call);
 767
 768                 if (is_Global(ptr)) {
 769                         ir_entity *ent = get_Global_entity(ptr);
 770
 771                         prop = get_entity_additional_properties(ent);
 772                 }
 773         }
 774         return (prop & (mtp_property_const|mtp_property_pure)) != 0;
 775 }  /* is_Call_pure */
 776
 777 /**
 778  * Follow the memory chain as long as there are only Loads,
 779  * alias free Stores, and constant Calls and try to replace the
 780  * current Load by a previous ones.
 781  * Note that in unreachable loops it might happen that we reach
 782  * load again, as well as we can fall into a cycle.
 783  * We break such cycles using a special visited flag.
 784  *
 785  * INC_MASTER() must be called before dive into
 786  */
 787 static unsigned follow_Mem_chain(ir_node *load, ir_node *curr) {
 788         unsigned res = 0;
 789         ldst_info_t *info = get_irn_link(load);
 790         ir_node *pred;
 791         ir_node *ptr       = get_Load_ptr(load);
 792         ir_node *mem       = get_Load_mem(load);
 793         ir_mode *load_mode = get_Load_mode(load);
 794
 795         for (pred = curr; load != pred; ) {
 796                 ldst_info_t *pred_info = get_irn_link(pred);
 797
 798                 /*
 799                  * BEWARE: one might think that checking the modes is useless, because
 800                  * if the pointers are identical, they refer to the same object.
 801                  * This is only true in strong typed languages, not in C were the following
 802                  * is possible a = *(ir_type1 *)p; b = *(ir_type2 *)p ...
 803                  */
 804                 if (is_Store(pred) && get_Store_ptr(pred) == ptr &&
 805                     can_use_stored_value(get_irn_mode(get_Store_value(pred)), load_mode)) {
 806                         /*
 807                          * a Load immediately after a Store -- a read after write.
 808                          * We may remove the Load, if both Load & Store does not have an exception handler
 809                          * OR they are in the same MacroBlock. In the latter case the Load cannot
 810                          * throw an exception when the previous Store was quiet.
 811                          *
 812                          * Why we need to check for Store Exception? If the Store cannot
 813                          * be executed (ROM) the exception handler might simply jump into
 814                          * the load MacroBlock :-(
 815                          * We could make it a little bit better if we would know that the exception
 816                          * handler of the Store jumps directly to the end...
 817                          */
 818                         if ((pred_info->projs[pn_Store_X_except] == NULL && info->projs[pn_Load_X_except] == NULL) ||
 819                             get_nodes_MacroBlock(load) == get_nodes_MacroBlock(pred)) {
 820                                 ir_node *value = get_Store_value(pred);
 821
 822                                 DBG_OPT_RAW(load, value);
 823
 824                                 /* add an convert if needed */
 825                                 if (get_irn_mode(get_Store_value(pred)) != load_mode) {
 826                                         value = new_r_Conv(current_ir_graph, get_nodes_block(load), value, load_mode);
 827                                 }
 828
 829                                 if (info->projs[pn_Load_M])
 830                                         exchange(info->projs[pn_Load_M], mem);
 831
 832                                 /* no exception */
 833                                 if (info->projs[pn_Load_X_except]) {
 834                                         exchange( info->projs[pn_Load_X_except], new_Bad());
 835                                         res |= CF_CHANGED;
 836                                 }
 837                                 if (info->projs[pn_Load_X_regular]) {
 838                                         exchange( info->projs[pn_Load_X_regular], new_r_Jmp(current_ir_graph, get_nodes_block(load)));
 839                                         res |= CF_CHANGED;
 840                                 }
 841
 842                                 if (info->projs[pn_Load_res])
 843                                         exchange(info->projs[pn_Load_res], value);
 844
 845                                 kill_node(load);
 846                                 reduce_adr_usage(ptr);
 847                                 return res | DF_CHANGED;
 848                         }
 849                 } else if (is_Load(pred) && get_Load_ptr(pred) == ptr &&
 850                            can_use_stored_value(get_Load_mode(pred), load_mode)) {
 851                         /*
 852                          * a Load after a Load -- a read after read.
 853                          * We may remove the second Load, if it does not have an exception handler
 854                          * OR they are in the same MacroBlock. In the later case the Load cannot
 855                          * throw an exception when the previous Load was quiet.
 856                          *
 857                          * Here, there is no need to check if the previous Load has an exception
 858                          * hander because they would have exact the same exception...
 859                          */
 860                         if (info->projs[pn_Load_X_except] == NULL || get_nodes_MacroBlock(load) == get_nodes_MacroBlock(pred)) {
 861                                 ir_node *value;
 862
 863                                 DBG_OPT_RAR(load, pred);
 864
 865                                 /* the result is used */
 866                                 if (info->projs[pn_Load_res]) {
 867                                         if (pred_info->projs[pn_Load_res] == NULL) {
 868                                                 /* create a new Proj again */
 869                                                 pred_info->projs[pn_Load_res] = new_r_Proj(current_ir_graph, get_nodes_block(pred), pred, get_Load_mode(pred), pn_Load_res);
 870                                         }
 871                                         value = pred_info->projs[pn_Load_res];
 872
 873                                         /* add an convert if needed */
 874                                         if (get_Load_mode(pred) != load_mode) {
 875                                                 value = new_r_Conv(current_ir_graph, get_nodes_block(load), value, load_mode);
 876                                         }
 877
 878                                         exchange(info->projs[pn_Load_res], value);
 879                                 }
 880
 881                                 if (info->projs[pn_Load_M])
 882                                         exchange(info->projs[pn_Load_M], mem);
 883
 884                                 /* no exception */
 885                                 if (info->projs[pn_Load_X_except]) {
 886                                         exchange(info->projs[pn_Load_X_except], new_Bad());
 887                                         res |= CF_CHANGED;
 888                                 }
 889                                 if (info->projs[pn_Load_X_regular]) {
 890                                         exchange( info->projs[pn_Load_X_regular], new_r_Jmp(current_ir_graph, get_nodes_block(load)));
 891                                         res |= CF_CHANGED;
 892                                 }
 893
 894                                 kill_node(load);
 895                                 reduce_adr_usage(ptr);
 896                                 return res |= DF_CHANGED;
 897                         }
 898                 }
 899
 900                 if (is_Store(pred)) {
 901                         /* check if we can pass through this store */
 902                         ir_alias_relation rel = get_alias_relation(
 903                                 current_ir_graph,
 904                                 get_Store_ptr(pred),
 905                                 get_irn_mode(get_Store_value(pred)),
 906                                 ptr, load_mode);
 907                         /* if the might be an alias, we cannot pass this Store */
 908                         if (rel != ir_no_alias)
 909                                 break;
 910                         pred = skip_Proj(get_Store_mem(pred));
 911                 } else if (is_Load(pred)) {
 912                         pred = skip_Proj(get_Load_mem(pred));
 913                 } else if (is_Call(pred)) {
 914                         if (is_Call_pure(pred)) {
 915                                 /* The called graph is at least pure, so there are no Store's
 916                                    in it. We can handle it like a Load and skip it. */
 917                                 pred = skip_Proj(get_Call_mem(pred));
 918                         } else {
 919                                 /* there might be Store's in the graph, stop here */
 920                                 break;
 921                         }
 922                 } else {
 923                         /* follow only Load chains */
 924                         break;
 925                 }
 926
 927                 /* check for cycles */
 928                 if (NODE_VISITED(pred_info))
 929                         break;
 930                 MARK_NODE(pred_info);
 931         }
 932
 933         if (is_Sync(pred)) {
 934                 int i;
 935
 936                 /* handle all Sync predecessors */
 937                 for (i = get_Sync_n_preds(pred) - 1; i >= 0; --i) {
 938                         res |= follow_Mem_chain(load, skip_Proj(get_Sync_pred(pred, i)));
 939                         if (res)
 940                                 return res;
 941                 }
 942         }
 943
 944         return res;
 945 }  /* follow_Mem_chain */
 946
 947 /*
 948  * Check if we can replace the load by a given const from
 949  * the const code irg.
 950  */
 951 ir_node *can_replace_load_by_const(const ir_node *load, ir_node *c) {
 952         ir_mode *c_mode = get_irn_mode(c);
 953         ir_mode *l_mode = get_Load_mode(load);
 954         ir_node *res    = NULL;
 955
 956         if (c_mode != l_mode) {
 957                 /* check, if the mode matches OR can be easily converted info */
 958                 if (is_reinterpret_cast(c_mode, l_mode)) {
 959                         /* we can safely cast */
 960                         dbg_info *dbg   = get_irn_dbg_info(load);
 961                         ir_node  *block = get_nodes_block(load);
 962
 963                         /* copy the value from the const code irg and cast it */
 964                         res = copy_const_value(dbg, c);
 965                         res = new_rd_Conv(dbg, current_ir_graph, block, res, l_mode);
 966                 }
 967         } else {
 968                 /* copy the value from the const code irg */
 969                 res = copy_const_value(get_irn_dbg_info(load), c);
 970         }
 971         return res;
 972 }  /* can_replace_load_by_const */
 973
 974 /**
 975  * optimize a Load
 976  *
 977  * @param load  the Load node
 978  */
 979 static unsigned optimize_load(ir_node *load)
 980 {
 981         ldst_info_t *info = get_irn_link(load);
 982         ir_node *mem, *ptr, *value;
 983         ir_entity *ent;
 984         unsigned res = 0;
 985
 986         /* do NOT touch volatile loads for now */
 987         if (get_Load_volatility(load) == volatility_is_volatile)
 988                 return 0;
 989
 990         /* the address of the load to be optimized */
 991         ptr = get_Load_ptr(load);
 992
 993         /*
 994          * Check if we can remove the exception from a Load:
 995          * This can be done, if the address is from an Sel(Alloc) and
 996          * the Sel type is a subtype of the allocated type.
 997          *
 998          * This optimizes some often used OO constructs,
 999          * like x = new O; x->t;
1000          */
1001         if (info->projs[pn_Load_X_except]) {
1002                 ir_node *addr = ptr;
1003
1004                 /* find base address */
1005                 while (is_Sel(addr))
1006                         addr = get_Sel_ptr(addr);
1007                 if (is_Alloc(skip_Proj(skip_Cast(addr)))) {
1008                         /* simple case: a direct load after an Alloc. Firm Alloc throw
1009                          * an exception in case of out-of-memory. So, there is no way for an
1010                          * exception in this load.
1011                          * This code is constructed by the "exception lowering" in the Jack compiler.
1012                          */
1013                         exchange(info->projs[pn_Load_X_except], new_Bad());
1014                         info->projs[pn_Load_X_except] = NULL;
1015                         exchange(info->projs[pn_Load_X_regular], new_r_Jmp(current_ir_graph, get_nodes_block(load)));
1016                         info->projs[pn_Load_X_regular] = NULL;
1017                         res |= CF_CHANGED;
1018                 }
1019         }
1020
1021         /* The mem of the Load. Must still be returned after optimization. */
1022         mem  = get_Load_mem(load);
1023
1024         if (! info->projs[pn_Load_res] && ! info->projs[pn_Load_X_except]) {
1025                 /* a Load which value is neither used nor exception checked, remove it */
1026                 exchange(info->projs[pn_Load_M], mem);
1027
1028                 if (info->projs[pn_Load_X_regular]) {
1029                         /* should not happen, but if it does, remove it */
1030                         exchange(info->projs[pn_Load_X_regular], new_r_Jmp(current_ir_graph, get_nodes_block(load)));
1031                         res |= CF_CHANGED;
1032                 }
1033                 kill_node(load);
1034                 reduce_adr_usage(ptr);
1035                 return res | DF_CHANGED;
1036         }
1037
1038         /* Load from a constant polymorphic field, where we can resolve
1039            polymorphism. */
1040         value = transform_polymorph_Load(load);
1041         if (value == NULL) {
1042                 /* check if we can determine the entity that will be loaded */
1043                 ent = find_constant_entity(ptr);
1044                 if (ent != NULL) {
1045                         if ((allocation_static == get_entity_allocation(ent)) &&
1046                                 (visibility_external_allocated != get_entity_visibility(ent))) {
1047                                 /* a static allocation that is not external: there should be NO exception
1048                                  * when loading even if we cannot replace the load itself. */
1049
1050                                 /* no exception, clear the info field as it might be checked later again */
1051                                 if (info->projs[pn_Load_X_except]) {
1052                                         exchange(info->projs[pn_Load_X_except], new_Bad());
1053                                         info->projs[pn_Load_X_except] = NULL;
1054                                         res |= CF_CHANGED;
1055                                 }
1056                                 if (info->projs[pn_Load_X_regular]) {
1057                                         exchange(info->projs[pn_Load_X_regular], new_r_Jmp(current_ir_graph, get_nodes_block(load)));
1058                                         info->projs[pn_Load_X_regular] = NULL;
1059                                         res |= CF_CHANGED;
1060                                 }
1061
1062                                 if (variability_constant == get_entity_variability(ent)) {
1063                                         if (is_atomic_entity(ent)) {
1064                                                 /* Might not be atomic after
1065                                                    lowering of Sels.  In this
1066                                                    case we could also load, but
1067                                                    it's more complicated. */
1068                                                 /* more simpler case: we load the content of a constant value:
1069                                                  * replace it by the constant itself
1070                                                  */
1071                                                 value = get_atomic_ent_value(ent);
1072                                         } else {
1073                                                 if (ent->has_initializer) {
1074                                                         /* new style initializer */
1075                                                         value = find_compound_ent_value(ptr);
1076                                                 } else {
1077                                                         /* old style initializer */
1078                                                         compound_graph_path *path = get_accessed_path(ptr);
1079
1080                                                         if (path != NULL) {
1081                                                                 assert(is_proper_compound_graph_path(path, get_compound_graph_path_length(path)-1));
1082
1083                                                                 value = get_compound_ent_value_by_path(ent, path);
1084                                                                 free_compound_graph_path(path);
1085                                                         }
1086                                                 }
1087                                         }
1088                                         if (value != NULL)
1089                                                 value = can_replace_load_by_const(load, value);
1090                                 }
1091                         }
1092                 }
1093         }
1094         if (value != NULL) {
1095                 /* we completely replace the load by this value */
1096                 if (info->projs[pn_Load_X_except]) {
1097                         exchange(info->projs[pn_Load_X_except], new_Bad());
1098                         info->projs[pn_Load_X_except] = NULL;
1099                         res |= CF_CHANGED;
1100                 }
1101                 if (info->projs[pn_Load_X_regular]) {
1102                         exchange(info->projs[pn_Load_X_regular], new_r_Jmp(current_ir_graph, get_nodes_block(load)));
1103                         info->projs[pn_Load_X_regular] = NULL;
1104                         res |= CF_CHANGED;
1105                 }
1106                 if (info->projs[pn_Load_M]) {
1107                         exchange(info->projs[pn_Load_M], mem);
1108                         res |= DF_CHANGED;
1109                 }
1110                 if (info->projs[pn_Load_res]) {
1111                         exchange(info->projs[pn_Load_res], value);
1112                         res |= DF_CHANGED;
1113                 }
1114                 kill_node(load);
1115                 reduce_adr_usage(ptr);
1116                 return res;
1117         }
1118
1119         /* Check, if the address of this load is used more than once.
1120          * If not, this load cannot be removed in any case. */
1121         if (get_irn_n_uses(ptr) <= 1)
1122                 return res;
1123
1124         /*
1125          * follow the memory chain as long as there are only Loads
1126          * and try to replace current Load or Store by a previous one.
1127          * Note that in unreachable loops it might happen that we reach
1128          * load again, as well as we can fall into a cycle.
1129          * We break such cycles using a special visited flag.
1130          */
1131         INC_MASTER();
1132         res = follow_Mem_chain(load, skip_Proj(mem));
1133         return res;
1134 }  /* optimize_load */
1135
1136 /**
1137  * Check whether a value of mode new_mode would completely overwrite a value
1138  * of mode old_mode in memory.
1139  */
1140 static int is_completely_overwritten(ir_mode *old_mode, ir_mode *new_mode)
1141 {
1142         return get_mode_size_bits(new_mode) >= get_mode_size_bits(old_mode);
1143 }  /* is_completely_overwritten */
1144
1145 /**
1146  * follow the memory chain as long as there are only Loads and alias free Stores.
1147  *
1148  * INC_MASTER() must be called before dive into
1149  */
1150 static unsigned follow_Mem_chain_for_Store(ir_node *store, ir_node *curr) {
1151         unsigned res = 0;
1152         ldst_info_t *info = get_irn_link(store);
1153         ir_node *pred;
1154         ir_node *ptr = get_Store_ptr(store);
1155         ir_node *mem = get_Store_mem(store);
1156         ir_node *value = get_Store_value(store);
1157         ir_mode *mode  = get_irn_mode(value);
1158         ir_node *block = get_nodes_block(store);
1159         ir_node *mblk  = get_Block_MacroBlock(block);
1160
1161         for (pred = curr; pred != store;) {
1162                 ldst_info_t *pred_info = get_irn_link(pred);
1163
1164                 /*
1165                  * BEWARE: one might think that checking the modes is useless, because
1166                  * if the pointers are identical, they refer to the same object.
1167                  * This is only true in strong typed languages, not is C were the following
1168                  * is possible *(ir_type1 *)p = a; *(ir_type2 *)p = b ...
1169                  * However, if the mode that is written have a bigger  or equal size the the old
1170                  * one, the old value is completely overwritten and can be killed ...
1171                  */
1172                 if (is_Store(pred) && get_Store_ptr(pred) == ptr &&
1173                     get_nodes_MacroBlock(pred) == mblk &&
1174                     is_completely_overwritten(get_irn_mode(get_Store_value(pred)), mode)) {
1175                         /*
1176                          * a Store after a Store in the same MacroBlock -- a write after write.
1177                          * We may remove the first Store, if it does not have an exception handler.
1178                          *
1179                          * TODO: What, if both have the same exception handler ???
1180                          */
1181                         if (get_Store_volatility(pred) != volatility_is_volatile && !pred_info->projs[pn_Store_X_except]) {
1182                                 DBG_OPT_WAW(pred, store);
1183                                 exchange(pred_info->projs[pn_Store_M], get_Store_mem(pred));
1184                                 kill_node(pred);
1185                                 reduce_adr_usage(ptr);
1186                                 return DF_CHANGED;
1187                         }
1188                 } else if (is_Load(pred) && get_Load_ptr(pred) == ptr &&
1189                            value == pred_info->projs[pn_Load_res]) {
1190                         /*
1191                          * a Store of a value just loaded from the same address
1192                          * -- a write after read.
1193                          * We may remove the Store, if it does not have an exception
1194                          * handler.
1195                          */
1196                         if (! info->projs[pn_Store_X_except]) {
1197                                 DBG_OPT_WAR(store, pred);
1198                                 exchange(info->projs[pn_Store_M], mem);
1199                                 kill_node(store);
1200                                 reduce_adr_usage(ptr);
1201                                 return DF_CHANGED;
1202                         }
1203                 }
1204
1205                 if (is_Store(pred)) {
1206                         /* check if we can pass through this store */
1207                         ir_alias_relation rel = get_alias_relation(
1208                                 current_ir_graph,
1209                                 get_Store_ptr(pred),
1210                                 get_irn_mode(get_Store_value(pred)),
1211                                 ptr, mode);
1212                         /* if the might be an alias, we cannot pass this Store */
1213                         if (rel != ir_no_alias)
1214                                 break;
1215                         pred = skip_Proj(get_Store_mem(pred));
1216                 } else if (is_Load(pred)) {
1217                         ir_alias_relation rel = get_alias_relation(
1218                                 current_ir_graph, get_Load_ptr(pred), get_Load_mode(pred),
1219                                 ptr, mode);
1220                         if (rel != ir_no_alias)
1221                                 break;
1222
1223                         pred = skip_Proj(get_Load_mem(pred));
1224                 } else {
1225                         /* follow only Load chains */
1226                         break;
1227                 }
1228
1229                 /* check for cycles */
1230                 if (NODE_VISITED(pred_info))
1231                         break;
1232                 MARK_NODE(pred_info);
1233         }
1234
1235         if (is_Sync(pred)) {
1236                 int i;
1237
1238                 /* handle all Sync predecessors */
1239                 for (i = get_Sync_n_preds(pred) - 1; i >= 0; --i) {
1240                         res |= follow_Mem_chain_for_Store(store, skip_Proj(get_Sync_pred(pred, i)));
1241                         if (res)
1242                                 break;
1243                 }
1244         }
1245         return res;
1246 }  /* follow_Mem_chain_for_Store */
1247
1248 /**
1249  * optimize a Store
1250  *
1251  * @param store  the Store node
1252  */
1253 static unsigned optimize_store(ir_node *store) {
1254         ir_node *ptr, *mem;
1255
1256         if (get_Store_volatility(store) == volatility_is_volatile)
1257                 return 0;
1258
1259         ptr = get_Store_ptr(store);
1260
1261         /* Check, if the address of this Store is used more than once.
1262          * If not, this Store cannot be removed in any case. */
1263         if (get_irn_n_uses(ptr) <= 1)
1264                 return 0;
1265
1266         mem = get_Store_mem(store);
1267
1268         /* follow the memory chain as long as there are only Loads */
1269         INC_MASTER();
1270
1271         return follow_Mem_chain_for_Store(store, skip_Proj(mem));
1272 }  /* optimize_store */
1273
1274 /**
1275  * walker, optimizes Phi after Stores to identical places:
1276  * Does the following optimization:
1277  * @verbatim
1278  *
1279  *   val1   val2   val3          val1  val2  val3
1280  *    |      |      |               \    |    /
1281  *  Store  Store  Store              \   |   /
1282  *      \    |    /                   PhiData
1283  *       \   |   /                       |
1284  *        \  |  /                      Store
1285  *          PhiM
1286  *
1287  * @endverbatim
1288  * This reduces the number of stores and allows for predicated execution.
1289  * Moves Stores back to the end of a function which may be bad.
1290  *
1291  * This is only possible if the predecessor blocks have only one successor.
1292  */
1293 static unsigned optimize_phi(ir_node *phi, walk_env_t *wenv)
1294 {
1295         int i, n;
1296         ir_node *store, *old_store, *ptr, *block, *phi_block, *phiM, *phiD, *exc, *projM;
1297         ir_mode *mode;
1298         ir_node **inM, **inD, **projMs;
1299         int *idx;
1300         dbg_info *db = NULL;
1301         ldst_info_t *info;
1302         block_info_t *bl_info;
1303         unsigned res = 0;
1304
1305         /* Must be a memory Phi */
1306         if (get_irn_mode(phi) != mode_M)
1307                 return 0;
1308
1309         n = get_Phi_n_preds(phi);
1310         if (n <= 0)
1311                 return 0;
1312
1313         /* must be only one user */
1314         projM = get_Phi_pred(phi, 0);
1315         if (get_irn_n_edges(projM) != 1)
1316                 return 0;
1317
1318         store = skip_Proj(projM);
1319         old_store = store;
1320         if (!is_Store(store))
1321                 return 0;
1322
1323         block = get_nodes_block(store);
1324
1325         /* abort on dead blocks */
1326         if (is_Block_dead(block))
1327                 return 0;
1328
1329         /* check if the block is post dominated by Phi-block
1330            and has no exception exit */
1331         bl_info = get_irn_link(block);
1332         if (bl_info->flags & BLOCK_HAS_EXC)
1333                 return 0;
1334
1335         phi_block = get_nodes_block(phi);
1336         if (! block_strictly_postdominates(phi_block, block))
1337                 return 0;
1338
1339         /* this is the address of the store */
1340         ptr  = get_Store_ptr(store);
1341         mode = get_irn_mode(get_Store_value(store));
1342         info = get_irn_link(store);
1343         exc  = info->exc_block;
1344
1345         for (i = 1; i < n; ++i) {
1346                 ir_node *pred = get_Phi_pred(phi, i);
1347
1348                 if (get_irn_n_edges(pred) != 1)
1349                         return 0;
1350
1351                 pred = skip_Proj(pred);
1352                 if (!is_Store(pred))
1353                         return 0;
1354
1355                 if (ptr != get_Store_ptr(pred) || mode != get_irn_mode(get_Store_value(pred)))
1356                         return 0;
1357
1358                 info = get_irn_link(pred);
1359
1360                 /* check, if all stores have the same exception flow */
1361                 if (exc != info->exc_block)
1362                         return 0;
1363
1364                 /* abort on dead blocks */
1365                 block = get_nodes_block(pred);
1366                 if (is_Block_dead(block))
1367                         return 0;
1368
1369                 /* check if the block is post dominated by Phi-block
1370                    and has no exception exit. Note that block must be different from
1371                    Phi-block, else we would move a Store from end End of a block to its
1372                    Start... */
1373                 bl_info = get_irn_link(block);
1374                 if (bl_info->flags & BLOCK_HAS_EXC)
1375                         return 0;
1376                 if (block == phi_block || ! block_postdominates(phi_block, block))
1377                         return 0;
1378         }
1379
1380         /*
1381          * ok, when we are here, we found all predecessors of a Phi that
1382          * are Stores to the same address and size. That means whatever
1383          * we do before we enter the block of the Phi, we do a Store.
1384          * So, we can move the Store to the current block:
1385          *
1386          *   val1    val2    val3          val1  val2  val3
1387          *    |       |       |               \    |    /
1388          * | Str | | Str | | Str |             \   |   /
1389          *      \     |     /                   PhiData
1390          *       \    |    /                       |
1391          *        \   |   /                       Str
1392          *           PhiM
1393          *
1394          * Is only allowed if the predecessor blocks have only one successor.
1395          */
1396
1397         NEW_ARR_A(ir_node *, projMs, n);
1398         NEW_ARR_A(ir_node *, inM, n);
1399         NEW_ARR_A(ir_node *, inD, n);
1400         NEW_ARR_A(int, idx, n);
1401
1402         /* Prepare: Collect all Store nodes.  We must do this
1403            first because we otherwise may loose a store when exchanging its
1404            memory Proj.
1405          */
1406         for (i = n - 1; i >= 0; --i) {
1407                 ir_node *store;
1408
1409                 projMs[i] = get_Phi_pred(phi, i);
1410                 assert(is_Proj(projMs[i]));
1411
1412                 store = get_Proj_pred(projMs[i]);
1413                 info  = get_irn_link(store);
1414
1415                 inM[i] = get_Store_mem(store);
1416                 inD[i] = get_Store_value(store);
1417                 idx[i] = info->exc_idx;
1418         }
1419         block = get_nodes_block(phi);
1420
1421         /* second step: create a new memory Phi */
1422         phiM = new_rd_Phi(get_irn_dbg_info(phi), current_ir_graph, block, n, inM, mode_M);
1423
1424         /* third step: create a new data Phi */
1425         phiD = new_rd_Phi(get_irn_dbg_info(phi), current_ir_graph, block, n, inD, mode);
1426
1427         /* rewire memory and kill the node */
1428         for (i = n - 1; i >= 0; --i) {
1429                 ir_node *proj  = projMs[i];
1430
1431                 if(is_Proj(proj)) {
1432                         ir_node *store = get_Proj_pred(proj);
1433                         exchange(proj, inM[i]);
1434                         kill_node(store);
1435                 }
1436         }
1437
1438         /* fourth step: create the Store */
1439         store = new_rd_Store(db, current_ir_graph, block, phiM, ptr, phiD);
1440 #ifdef DO_CACHEOPT
1441         co_set_irn_name(store, co_get_irn_ident(old_store));
1442 #endif
1443
1444         projM = new_rd_Proj(NULL, current_ir_graph, block, store, mode_M, pn_Store_M);
1445
1446         info = get_ldst_info(store, &wenv->obst);
1447         info->projs[pn_Store_M] = projM;
1448
1449         /* fifths step: repair exception flow */
1450         if (exc) {
1451                 ir_node *projX = new_rd_Proj(NULL, current_ir_graph, block, store, mode_X, pn_Store_X_except);
1452
1453                 info->projs[pn_Store_X_except] = projX;
1454                 info->exc_block                = exc;
1455                 info->exc_idx                  = idx[0];
1456
1457                 for (i = 0; i < n; ++i) {
1458                         set_Block_cfgpred(exc, idx[i], projX);
1459                 }
1460
1461                 if (n > 1) {
1462                         /* the exception block should be optimized as some inputs are identical now */
1463                 }
1464
1465                 res |= CF_CHANGED;
1466         }
1467
1468         /* sixth step: replace old Phi */
1469         exchange(phi, projM);
1470
1471         return res | DF_CHANGED;
1472 }  /* optimize_phi */
1473
1474 /**
1475  * walker, do the optimizations
1476  */
1477 static void do_load_store_optimize(ir_node *n, void *env) {
1478         walk_env_t *wenv = env;
1479
1480         switch (get_irn_opcode(n)) {
1481
1482         case iro_Load:
1483                 wenv->changes |= optimize_load(n);
1484                 break;
1485
1486         case iro_Store:
1487                 wenv->changes |= optimize_store(n);
1488                 break;
1489
1490         case iro_Phi:
1491                 wenv->changes |= optimize_phi(n, wenv);
1492                 break;
1493
1494         default:
1495                 ;
1496         }
1497 }  /* do_load_store_optimize */
1498
1499 /** A scc. */
1500 typedef struct scc {
1501         ir_node *head;          /**< the head of the list */
1502 } scc;
1503
1504 /** A node entry. */
1505 typedef struct node_entry {
1506         unsigned DFSnum;    /**< the DFS number of this node */
1507         unsigned low;       /**< the low number of this node */
1508         ir_node  *header;   /**< the header of this node */
1509         int      in_stack;  /**< flag, set if the node is on the stack */
1510         ir_node  *next;     /**< link to the next node the the same scc */
1511         scc      *pscc;     /**< the scc of this node */
1512         unsigned POnum;     /**< the post order number for blocks */
1513 } node_entry;
1514
1515 /** A loop entry. */
1516 typedef struct loop_env {
1517         ir_phase ph;           /**< the phase object */
1518         ir_node  **stack;      /**< the node stack */
1519         int      tos;          /**< tos index */
1520         unsigned nextDFSnum;   /**< the current DFS number */
1521         unsigned POnum;        /**< current post order number */
1522
1523         unsigned changes;      /**< a bitmask of graph changes */
1524 } loop_env;
1525
1526 /**
1527 * Gets the node_entry of a node
1528 */
1529 static node_entry *get_irn_ne(ir_node *irn, loop_env *env) {
1530         ir_phase   *ph = &env->ph;
1531         node_entry *e  = phase_get_irn_data(&env->ph, irn);
1532
1533         if (! e) {
1534                 e = phase_alloc(ph, sizeof(*e));
1535                 memset(e, 0, sizeof(*e));
1536                 phase_set_irn_data(ph, irn, e);
1537         }
1538         return e;
1539 }  /* get_irn_ne */
1540
1541 /**
1542  * Push a node onto the stack.
1543  *
1544  * @param env   the loop environment
1545  * @param n     the node to push
1546  */
1547 static void push(loop_env *env, ir_node *n) {
1548         node_entry *e;
1549
1550         if (env->tos == ARR_LEN(env->stack)) {
1551                 int nlen = ARR_LEN(env->stack) * 2;
1552                 ARR_RESIZE(ir_node *, env->stack, nlen);
1553         }
1554         env->stack[env->tos++] = n;
1555         e = get_irn_ne(n, env);
1556         e->in_stack = 1;
1557 }  /* push */
1558
1559 /**
1560  * pop a node from the stack
1561  *
1562  * @param env   the loop environment
1563  *
1564  * @return  The topmost node
1565  */
1566 static ir_node *pop(loop_env *env) {
1567         ir_node *n = env->stack[--env->tos];
1568         node_entry *e = get_irn_ne(n, env);
1569
1570         e->in_stack = 0;
1571         return n;
1572 }  /* pop */
1573
1574 /**
1575  * Check if irn is a region constant.
1576  * The block or irn must strictly dominate the header block.
1577  *
1578  * @param irn           the node to check
1579  * @param header_block  the header block of the induction variable
1580  */
1581 static int is_rc(ir_node *irn, ir_node *header_block) {
1582         ir_node *block = get_nodes_block(irn);
1583
1584         return (block != header_block) && block_dominates(block, header_block);
1585 }  /* is_rc */
1586
1587 typedef struct phi_entry phi_entry;
1588 struct phi_entry {
1589         ir_node   *phi;    /**< A phi with a region const memory. */
1590         int       pos;     /**< The position of the region const memory */
1591         ir_node   *load;   /**< the newly created load for this phi */
1592         phi_entry *next;
1593 };
1594
1595 /**
1596  * Move loops out of loops if possible.
1597  *
1598  * @param pscc   the loop described by an SCC
1599  * @param env    the loop environment
1600  */
1601 static void move_loads_out_of_loops(scc *pscc, loop_env *env) {
1602         ir_node   *phi, *load, *next, *other, *next_other;
1603         ir_entity *ent;
1604         int       j;
1605         phi_entry *phi_list = NULL;
1606
1607         /* collect all outer memories */
1608         for (phi = pscc->head; phi != NULL; phi = next) {
1609                 node_entry *ne = get_irn_ne(phi, env);
1610                 next = ne->next;
1611
1612                 /* check all memory Phi's */
1613                 if (! is_Phi(phi))
1614                         continue;
1615
1616                 assert(get_irn_mode(phi) == mode_M && "DFS geturn non-memory Phi");
1617
1618                 for (j = get_irn_arity(phi) - 1; j >= 0; --j) {
1619                         ir_node    *pred = get_irn_n(phi, j);
1620                         node_entry *pe   = get_irn_ne(pred, env);
1621
1622                         if (pe->pscc != ne->pscc) {
1623                                 /* not in the same SCC, is region const */
1624                                 phi_entry *pe = phase_alloc(&env->ph, sizeof(*pe));
1625
1626                                 pe->phi  = phi;
1627                                 pe->pos  = j;
1628                                 pe->next = phi_list;
1629                                 phi_list = pe;
1630                         }
1631                 }
1632         }
1633         /* no Phis no fun */
1634         assert(phi_list != NULL && "DFS found a loop without Phi");
1635
1636         for (load = pscc->head; load; load = next) {
1637                 ir_mode *load_mode;
1638                 node_entry *ne = get_irn_ne(load, env);
1639                 next = ne->next;
1640
1641                 if (is_Load(load)) {
1642                         ldst_info_t *info = get_irn_link(load);
1643                         ir_node     *ptr = get_Load_ptr(load);
1644
1645                         /* for now, we cannot handle Loads with exceptions */
1646                         if (info->projs[pn_Load_res] == NULL || info->projs[pn_Load_X_regular] != NULL || info->projs[pn_Load_X_except] != NULL)
1647                                 continue;
1648
1649                         /* for now, we can only handle Load(Global) */
1650                         if (! is_Global(ptr))
1651                                 continue;
1652                         ent = get_Global_entity(ptr);
1653                         load_mode = get_Load_mode(load);
1654                         for (other = pscc->head; other != NULL; other = next_other) {
1655                                 node_entry *ne = get_irn_ne(other, env);
1656                                 next_other = ne->next;
1657
1658                                 if (is_Store(other)) {
1659                                         ir_alias_relation rel = get_alias_relation(
1660                                                 current_ir_graph,
1661                                                 get_Store_ptr(other),
1662                                                 get_irn_mode(get_Store_value(other)),
1663                                                 ptr, load_mode);
1664                                         /* if the might be an alias, we cannot pass this Store */
1665                                         if (rel != ir_no_alias)
1666                                                 break;
1667                                 }
1668                                 /* only pure Calls are allowed here, so ignore them */
1669                         }
1670                         if (other == NULL) {
1671                                 ldst_info_t *ninfo;
1672                                 phi_entry   *pe;
1673                                 dbg_info    *db;
1674
1675                                 /* for now, we cannot handle more than one input */
1676                                 if (phi_list->next != NULL)
1677                                         return;
1678
1679                                 /* yep, no aliasing Store found, Load can be moved */
1680                                 DB((dbg, LEVEL_1, "  Found a Load that could be moved: %+F\n", load));
1681
1682                                 db   = get_irn_dbg_info(load);
1683                                 for (pe = phi_list; pe != NULL; pe = pe->next) {
1684                                         int     pos   = pe->pos;
1685                                         ir_node *phi  = pe->phi;
1686                                         ir_node *blk  = get_nodes_block(phi);
1687                                         ir_node *pred = get_Block_cfgpred_block(blk, pos);
1688                                         ir_node *irn, *mem;
1689
1690                                         pe->load = irn = new_rd_Load(db, current_ir_graph, pred, get_Phi_pred(phi, pos), ptr, load_mode);
1691                                         ninfo = get_ldst_info(irn, phase_obst(&env->ph));
1692
1693                                         ninfo->projs[pn_Load_M] = mem = new_r_Proj(current_ir_graph, pred, irn, mode_M, pn_Load_M);
1694                                         set_Phi_pred(phi, pos, mem);
1695
1696                                         ninfo->projs[pn_Load_res] = new_r_Proj(current_ir_graph, pred, irn, load_mode, pn_Load_res);
1697
1698                                         DB((dbg, LEVEL_1, "  Created %+F in %+F\n", irn, pred));
1699                                 }
1700
1701                                 /* now kill the old Load */
1702                                 exchange(info->projs[pn_Load_M], get_Load_mem(load));
1703                                 exchange(info->projs[pn_Load_res], ninfo->projs[pn_Load_res]);
1704
1705                                 env->changes |= DF_CHANGED;
1706                         }
1707                 }
1708         }
1709 }  /* move_loads_out_of_loops */
1710
1711 /**
1712  * Process a loop SCC.
1713  *
1714  * @param pscc  the SCC
1715  * @param env   the loop environment
1716  */
1717 static void process_loop(scc *pscc, loop_env *env) {
1718         ir_node *irn, *next, *header = NULL;
1719         node_entry *b, *h = NULL;
1720         int j, only_phi, num_outside, process = 0;
1721         ir_node *out_rc;
1722
1723         /* find the header block for this scc */
1724         for (irn = pscc->head; irn; irn = next) {
1725                 node_entry *e = get_irn_ne(irn, env);
1726                 ir_node *block = get_nodes_block(irn);
1727
1728                 next = e->next;
1729                 b = get_irn_ne(block, env);
1730
1731                 if (header) {
1732                         if (h->POnum < b->POnum) {
1733                                 header = block;
1734                                 h      = b;
1735                         }
1736                 }
1737                 else {
1738                         header = block;
1739                         h      = b;
1740                 }
1741         }
1742
1743         /* check if this scc contains only Phi, Loads or Stores nodes */
1744         only_phi    = 1;
1745         num_outside = 0;
1746         out_rc      = NULL;
1747         for (irn = pscc->head; irn; irn = next) {
1748                 node_entry *e = get_irn_ne(irn, env);
1749
1750                 next = e->next;
1751                 switch (get_irn_opcode(irn)) {
1752                 case iro_Call:
1753                         if (is_Call_pure(irn)) {
1754                                 /* pure calls can be treated like loads */
1755                                 only_phi = 0;
1756                                 break;
1757                         }
1758                         /* non-pure calls must be handle like may-alias Stores */
1759                         goto fail;
1760                 case iro_CopyB:
1761                         /* cannot handle CopyB yet */
1762                         goto fail;
1763                 case iro_Load:
1764                         process = 1;
1765                         if (get_Load_volatility(irn) == volatility_is_volatile) {
1766                                 /* cannot handle loops with volatile Loads */
1767                                 goto fail;
1768                         }
1769                         only_phi = 0;
1770                         break;
1771                 case iro_Store:
1772                         if (get_Store_volatility(irn) == volatility_is_volatile) {
1773                                 /* cannot handle loops with volatile Stores */
1774                                 goto fail;
1775                         }
1776                         only_phi = 0;
1777                         break;
1778                 default:
1779                         only_phi = 0;
1780                         break;
1781                 case iro_Phi:
1782                         for (j = get_irn_arity(irn) - 1; j >= 0; --j) {
1783                                 ir_node *pred  = get_irn_n(irn, j);
1784                                 node_entry *pe = get_irn_ne(pred, env);
1785
1786                                 if (pe->pscc != e->pscc) {
1787                                         /* not in the same SCC, must be a region const */
1788                                         if (! is_rc(pred, header)) {
1789                                                 /* not a memory loop */
1790                                                 goto fail;
1791                                         }
1792                                         if (! out_rc) {
1793                                                 out_rc = pred;
1794                                                 ++num_outside;
1795                                         } else if (out_rc != pred) {
1796                                                 ++num_outside;
1797                                         }
1798                                 }
1799                         }
1800                         break;
1801                 }
1802         }
1803         if (! process)
1804                 goto fail;
1805
1806         /* found a memory loop */
1807         DB((dbg, LEVEL_2, "  Found a memory loop:\n  "));
1808         if (only_phi && num_outside == 1) {
1809                 /* a phi cycle with only one real predecessor can be collapsed */
1810                 DB((dbg, LEVEL_2, "  Found an USELESS Phi cycle:\n  "));
1811
1812                 for (irn = pscc->head; irn; irn = next) {
1813                         node_entry *e = get_irn_ne(irn, env);
1814                         next = e->next;
1815                         e->header = NULL;
1816                         exchange(irn, out_rc);
1817                 }
1818                 env->changes |= DF_CHANGED;
1819                 return;
1820         }
1821
1822         /* set the header for every node in this scc */
1823         for (irn = pscc->head; irn; irn = next) {
1824                 node_entry *e = get_irn_ne(irn, env);
1825                 e->header = header;
1826                 next = e->next;
1827                 DB((dbg, LEVEL_2, " %+F,", irn));
1828         }
1829         DB((dbg, LEVEL_2, "\n"));
1830
1831         move_loads_out_of_loops(pscc, env);
1832
1833 fail:
1834         ;
1835 }  /* process_loop */
1836
1837 /**
1838  * Process a SCC.
1839  *
1840  * @param pscc  the SCC
1841  * @param env   the loop environment
1842  */
1843 static void process_scc(scc *pscc, loop_env *env) {
1844         ir_node *head = pscc->head;
1845         node_entry *e = get_irn_ne(head, env);
1846
1847 #ifdef DEBUG_libfirm
1848         {
1849                 ir_node *irn, *next;
1850
1851                 DB((dbg, LEVEL_4, " SCC at %p:\n ", pscc));
1852                 for (irn = pscc->head; irn; irn = next) {
1853                         node_entry *e = get_irn_ne(irn, env);
1854
1855                         next = e->next;
1856
1857                         DB((dbg, LEVEL_4, " %+F,", irn));
1858                 }
1859                 DB((dbg, LEVEL_4, "\n"));
1860         }
1861 #endif
1862
1863         if (e->next != NULL) {
1864                 /* this SCC has more than one member */
1865                 process_loop(pscc, env);
1866         }
1867 }  /* process_scc */
1868
1869 /**
1870  * Do Tarjan's SCC algorithm and drive load/store optimization.
1871  *
1872  * @param irn  start at this node
1873  * @param env  the loop environment
1874  */
1875 static void dfs(ir_node *irn, loop_env *env)
1876 {
1877         int i, n;
1878         node_entry *node = get_irn_ne(irn, env);
1879
1880         mark_irn_visited(irn);
1881
1882         node->DFSnum = env->nextDFSnum++;
1883         node->low    = node->DFSnum;
1884         push(env, irn);
1885
1886         /* handle preds */
1887         if (is_Phi(irn) || is_Sync(irn)) {
1888                 n = get_irn_arity(irn);
1889                 for (i = 0; i < n; ++i) {
1890                         ir_node *pred = get_irn_n(irn, i);
1891                         node_entry *o = get_irn_ne(pred, env);
1892
1893                         if (irn_not_visited(pred)) {
1894                                 dfs(pred, env);
1895                                 node->low = MIN(node->low, o->low);
1896                         }
1897                         if (o->DFSnum < node->DFSnum && o->in_stack)
1898                                 node->low = MIN(o->DFSnum, node->low);
1899                 }
1900         } else if (is_fragile_op(irn)) {
1901                 ir_node *pred = get_fragile_op_mem(irn);
1902                 node_entry *o = get_irn_ne(pred, env);
1903
1904                 if (irn_not_visited(pred)) {
1905                         dfs(pred, env);
1906                         node->low = MIN(node->low, o->low);
1907                 }
1908                 if (o->DFSnum < node->DFSnum && o->in_stack)
1909                         node->low = MIN(o->DFSnum, node->low);
1910         } else if (is_Proj(irn)) {
1911                 ir_node *pred = get_Proj_pred(irn);
1912                 node_entry *o = get_irn_ne(pred, env);
1913
1914                 if (irn_not_visited(pred)) {
1915                         dfs(pred, env);
1916                         node->low = MIN(node->low, o->low);
1917                 }
1918                 if (o->DFSnum < node->DFSnum && o->in_stack)
1919                         node->low = MIN(o->DFSnum, node->low);
1920         }
1921         else {
1922                  /* IGNORE predecessors */
1923         }
1924
1925         if (node->low == node->DFSnum) {
1926                 scc *pscc = phase_alloc(&env->ph, sizeof(*pscc));
1927                 ir_node *x;
1928
1929                 pscc->head = NULL;
1930                 do {
1931                         node_entry *e;
1932
1933                         x = pop(env);
1934                         e = get_irn_ne(x, env);
1935                         e->pscc    = pscc;
1936                         e->next    = pscc->head;
1937                         pscc->head = x;
1938                 } while (x != irn);
1939
1940                 process_scc(pscc, env);
1941         }
1942 }  /* dfs */
1943
1944 /**
1945  * Do the DFS on the memory edges a graph.
1946  *
1947  * @param irg  the graph to process
1948  * @param env  the loop environment
1949  */
1950 static void do_dfs(ir_graph *irg, loop_env *env) {
1951         ir_graph *rem = current_ir_graph;
1952         ir_node  *endblk, *end;
1953         int      i;
1954
1955         current_ir_graph = irg;
1956         inc_irg_visited(irg);
1957
1958         /* visit all memory nodes */
1959         endblk = get_irg_end_block(irg);
1960         for (i = get_Block_n_cfgpreds(endblk) - 1; i >= 0; --i) {
1961                 ir_node *pred = get_Block_cfgpred(endblk, i);
1962
1963                 pred = skip_Proj(pred);
1964                 if (is_Return(pred))
1965                         dfs(get_Return_mem(pred), env);
1966                 else if (is_Raise(pred))
1967                         dfs(get_Raise_mem(pred), env);
1968                 else if (is_fragile_op(pred))
1969                         dfs(get_fragile_op_mem(pred), env);
1970                 else {
1971                         assert(0 && "Unknown EndBlock predecessor");
1972                 }
1973         }
1974
1975         /* visit the keep-alives */
1976         end = get_irg_end(irg);
1977         for (i = get_End_n_keepalives(end) - 1; i >= 0; --i) {
1978                 ir_node *ka = get_End_keepalive(end, i);
1979
1980                 if (is_Phi(ka) && irn_not_visited(ka))
1981                         dfs(ka, env);
1982         }
1983         current_ir_graph = rem;
1984 }  /* do_dfs */
1985
1986 /**
1987  * Initialize new phase data. We do this always explicit, so return NULL here
1988  */
1989 static void *init_loop_data(ir_phase *ph, const ir_node *irn, void *data) {
1990         (void)ph;
1991         (void)irn;
1992         (void)data;
1993         return NULL;
1994 }  /* init_loop_data */
1995
1996 /**
1997  * Optimize Loads/Stores in loops.
1998  *
1999  * @param irg  the graph
2000  */
2001 static int optimize_loops(ir_graph *irg) {
2002         loop_env env;
2003
2004         env.stack         = NEW_ARR_F(ir_node *, 128);
2005         env.tos           = 0;
2006         env.nextDFSnum    = 0;
2007         env.POnum         = 0;
2008         env.changes       = 0;
2009         phase_init(&env.ph, "ldstopt", irg, PHASE_DEFAULT_GROWTH, init_loop_data, NULL);
2010
2011         /* calculate the SCC's and drive loop optimization. */
2012         do_dfs(irg, &env);
2013
2014         DEL_ARR_F(env.stack);
2015         phase_free(&env.ph);
2016
2017         return env.changes;
2018 }  /* optimize_loops */
2019
2020 /*
2021  * do the load store optimization
2022  */
2023 void optimize_load_store(ir_graph *irg) {
2024         walk_env_t env;
2025
2026         FIRM_DBG_REGISTER(dbg, "firm.opt.ldstopt");
2027
2028         assert(get_irg_phase_state(irg) != phase_building);
2029         assert(get_irg_pinned(irg) != op_pin_state_floats &&
2030                 "LoadStore optimization needs pinned graph");
2031
2032         /* we need landing pads */
2033         remove_critical_cf_edges(irg);
2034
2035         edges_assure(irg);
2036
2037         /* for Phi optimization post-dominators are needed ... */
2038         assure_postdoms(irg);
2039
2040         if (get_opt_alias_analysis()) {
2041                 assure_irg_address_taken_computed(irg);
2042                 assure_irp_globals_address_taken_computed();
2043         }
2044
2045         obstack_init(&env.obst);
2046         env.changes = 0;
2047
2048         /* init the links, then collect Loads/Stores/Proj's in lists */
2049         master_visited = 0;
2050         irg_walk_graph(irg, firm_clear_link, collect_nodes, &env);
2051
2052         /* now we have collected enough information, optimize */
2053         irg_walk_graph(irg, NULL, do_load_store_optimize, &env);
2054
2055         env.changes |= optimize_loops(irg);
2056
2057         obstack_free(&env.obst, NULL);
2058
2059         /* Handle graph state */
2060         if (env.changes) {
2061                 set_irg_outs_inconsistent(irg);
2062         }
2063
2064         if (env.changes & CF_CHANGED) {
2065                 /* is this really needed: Yes, control flow changed, block might
2066                 have Bad() predecessors. */
2067                 set_irg_doms_inconsistent(irg);
2068         }
2069 }  /* optimize_load_store */