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