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 #include "config.h"
  27
  28 #include <string.h>
  29
  30 #include "iroptimize.h"
  31 #include "irnode_t.h"
  32 #include "irgraph_t.h"
  33 #include "irmode_t.h"
  34 #include "iropt_t.h"
  35 #include "ircons_t.h"
  36 #include "irgmod.h"
  37 #include "irgwalk.h"
  38 #include "irvrfy.h"
  39 #include "tv_t.h"
  40 #include "dbginfo_t.h"
  41 #include "iropt_dbg.h"
  42 #include "irflag_t.h"
  43 #include "array_t.h"
  44 #include "irhooks.h"
  45 #include "iredges.h"
  46 #include "irpass.h"
  47 #include "opt_polymorphy.h"
  48 #include "irmemory.h"
  49 #include "irphase_t.h"
  50 #include "irgopt.h"
  51 #include "set.h"
  52 #include "debug.h"
  53
  54 /** The debug handle. */
  55 DEBUG_ONLY(static firm_dbg_module_t *dbg;)
  56
  57 #ifdef DO_CACHEOPT
  58 #include "cacheopt/cachesim.h"
  59 #endif
  60
  61 #undef IMAX
  62 #define IMAX(a,b)       ((a) > (b) ? (a) : (b))
  63
  64 #define MAX_PROJ        IMAX(IMAX(pn_Load_max, pn_Store_max), pn_Call_max)
  65
  66 enum changes_t {
  67         DF_CHANGED = 1,       /**< data flow changed */
  68         CF_CHANGED = 2,       /**< control flow changed */
  69 };
  70
  71 /**
  72  * walker environment
  73  */
  74 typedef struct _walk_env_t {
  75         struct obstack obst;          /**< list of all stores */
  76         unsigned changes;             /**< a bitmask of graph changes */
  77 } walk_env_t;
  78
  79 /** A Load/Store info. */
  80 typedef struct _ldst_info_t {
  81         ir_node  *projs[MAX_PROJ];    /**< list of Proj's of this node */
  82         ir_node  *exc_block;          /**< the exception block if available */
  83         int      exc_idx;             /**< predecessor index in the exception block */
  84         unsigned visited;             /**< visited counter for breaking loops */
  85 } ldst_info_t;
  86
  87 /**
  88  * flags for control flow.
  89  */
  90 enum block_flags_t {
  91         BLOCK_HAS_COND = 1,      /**< Block has conditional control flow */
  92         BLOCK_HAS_EXC  = 2       /**< Block has exceptional control flow */
  93 };
  94
  95 /**
  96  * a Block info.
  97  */
  98 typedef struct _block_info_t {
  99         unsigned flags;               /**< flags for the block */
 100 } block_info_t;
 101
 102 /** the master visited flag for loop detection. */
 103 static unsigned master_visited = 0;
 104
 105 #define INC_MASTER()       ++master_visited
 106 #define MARK_NODE(info)    (info)->visited = master_visited
 107 #define NODE_VISITED(info) (info)->visited >= master_visited
 108
 109 /**
 110  * get the Load/Store info of a node
 111  */
 112 static ldst_info_t *get_ldst_info(ir_node *node, struct obstack *obst)
 113 {
 114         ldst_info_t *info = get_irn_link(node);
 115
 116         if (! info) {
 117                 info = OALLOCZ(obst, ldst_info_t);
 118                 set_irn_link(node, info);
 119         }
 120         return info;
 121 }  /* get_ldst_info */
 122
 123 /**
 124  * get the Block info of a node
 125  */
 126 static block_info_t *get_block_info(ir_node *node, struct obstack *obst)
 127 {
 128         block_info_t *info = get_irn_link(node);
 129
 130         if (! info) {
 131                 info = OALLOCZ(obst, block_info_t);
 132                 set_irn_link(node, info);
 133         }
 134         return info;
 135 }  /* get_block_info */
 136
 137 /**
 138  * update the projection info for a Load/Store
 139  */
 140 static unsigned update_projs(ldst_info_t *info, ir_node *proj)
 141 {
 142         long nr = get_Proj_proj(proj);
 143
 144         assert(0 <= nr && nr <= MAX_PROJ && "Wrong proj from LoadStore");
 145
 146         if (info->projs[nr]) {
 147                 /* there is already one, do CSE */
 148                 exchange(proj, info->projs[nr]);
 149                 return DF_CHANGED;
 150         }
 151         else {
 152                 info->projs[nr] = proj;
 153                 return 0;
 154         }
 155 }  /* update_projs */
 156
 157 /**
 158  * update the exception block info for a Load/Store node.
 159  *
 160  * @param info   the load/store info struct
 161  * @param block  the exception handler block for this load/store
 162  * @param pos    the control flow input of the block
 163  */
 164 static unsigned update_exc(ldst_info_t *info, ir_node *block, int pos)
 165 {
 166         assert(info->exc_block == NULL && "more than one exception block found");
 167
 168         info->exc_block = block;
 169         info->exc_idx   = pos;
 170         return 0;
 171 }  /* update_exc */
 172
 173 /** Return the number of uses of an address node */
 174 #define get_irn_n_uses(adr)     get_irn_n_edges(adr)
 175
 176 /**
 177  * walker, collects all Load/Store/Proj nodes
 178  *
 179  * walks from Start -> End
 180  */
 181 static void collect_nodes(ir_node *node, void *env)
 182 {
 183         ir_opcode   opcode = get_irn_opcode(node);
 184         ir_node     *pred, *blk, *pred_blk;
 185         ldst_info_t *ldst_info;
 186         walk_env_t  *wenv = env;
 187
 188         if (opcode == iro_Proj) {
 189                 pred   = get_Proj_pred(node);
 190                 opcode = get_irn_opcode(pred);
 191
 192                 if (opcode == iro_Load || opcode == iro_Store || opcode == iro_Call) {
 193                         ldst_info = get_ldst_info(pred, &wenv->obst);
 194
 195                         wenv->changes |= update_projs(ldst_info, node);
 196
 197                         /*
 198                          * Place the Proj's to the same block as the
 199                          * predecessor Load. This is always ok and prevents
 200                          * "non-SSA" form after optimizations if the Proj
 201                          * is in a wrong block.
 202                          */
 203                         blk      = get_nodes_block(node);
 204                         pred_blk = get_nodes_block(pred);
 205                         if (blk != pred_blk) {
 206                                 wenv->changes |= DF_CHANGED;
 207                                 set_nodes_block(node, pred_blk);
 208                         }
 209                 }
 210         } else if (opcode == iro_Block) {
 211                 int i;
 212
 213                 for (i = get_Block_n_cfgpreds(node) - 1; i >= 0; --i) {
 214                         ir_node      *pred_block, *proj;
 215                         block_info_t *bl_info;
 216                         int          is_exc = 0;
 217
 218                         pred = proj = get_Block_cfgpred(node, i);
 219
 220                         if (is_Proj(proj)) {
 221                                 pred   = get_Proj_pred(proj);
 222                                 is_exc = get_Proj_proj(proj) == pn_Generic_X_except;
 223                         }
 224
 225                         /* ignore Bad predecessors, they will be removed later */
 226                         if (is_Bad(pred))
 227                                 continue;
 228
 229                         pred_block = get_nodes_block(pred);
 230                         bl_info    = get_block_info(pred_block, &wenv->obst);
 231
 232                         if (is_fragile_op(pred) && is_exc)
 233                                 bl_info->flags |= BLOCK_HAS_EXC;
 234                         else if (is_irn_forking(pred))
 235                                 bl_info->flags |= BLOCK_HAS_COND;
 236
 237                         opcode = get_irn_opcode(pred);
 238                         if (is_exc && (opcode == iro_Load || opcode == iro_Store || opcode == iro_Call)) {
 239                                 ldst_info = get_ldst_info(pred, &wenv->obst);
 240
 241                                 wenv->changes |= update_exc(ldst_info, node, i);
 242                         }
 243                 }
 244         }
 245 }  /* collect_nodes */
 246
 247 /**
 248  * Returns an entity if the address ptr points to a constant one.
 249  *
 250  * @param ptr  the address
 251  *
 252  * @return an entity or NULL
 253  */
 254 static ir_entity *find_constant_entity(ir_node *ptr)
 255 {
 256         for (;;) {
 257                 if (is_SymConst(ptr) && get_SymConst_kind(ptr) == symconst_addr_ent) {
 258                         return get_SymConst_entity(ptr);
 259                 } else if (is_Sel(ptr)) {
 260                         ir_entity *ent = get_Sel_entity(ptr);
 261                         ir_type   *tp  = get_entity_owner(ent);
 262
 263                         /* Do not fiddle with polymorphism. */
 264                         if (is_Class_type(get_entity_owner(ent)) &&
 265                                 ((get_entity_n_overwrites(ent)    != 0) ||
 266                                 (get_entity_n_overwrittenby(ent) != 0)   ) )
 267                                 return NULL;
 268
 269                         if (is_Array_type(tp)) {
 270                                 /* check bounds */
 271                                 int i, n;
 272
 273                                 for (i = 0, n = get_Sel_n_indexs(ptr); i < n; ++i) {
 274                                         ir_node *bound;
 275                                         tarval *tlower, *tupper;
 276                                         ir_node *index = get_Sel_index(ptr, i);
 277                                         tarval *tv     = computed_value(index);
 278
 279                                         /* check if the index is constant */
 280                                         if (tv == tarval_bad)
 281                                                 return NULL;
 282
 283                                         bound  = get_array_lower_bound(tp, i);
 284                                         tlower = computed_value(bound);
 285                                         bound  = get_array_upper_bound(tp, i);
 286                                         tupper = computed_value(bound);
 287
 288                                         if (tlower == tarval_bad || tupper == tarval_bad)
 289                                                 return NULL;
 290
 291                                         if (tarval_cmp(tv, tlower) & pn_Cmp_Lt)
 292                                                 return NULL;
 293                                         if (tarval_cmp(tupper, tv) & pn_Cmp_Lt)
 294                                                 return NULL;
 295
 296                                         /* ok, bounds check finished */
 297                                 }
 298                         }
 299
 300                         if (get_entity_linkage(ent) & IR_LINKAGE_CONSTANT)
 301                                 return ent;
 302
 303                         /* try next */
 304                         ptr = get_Sel_ptr(ptr);
 305                 } else if (is_Add(ptr)) {
 306                         ir_node *l = get_Add_left(ptr);
 307                         ir_node *r = get_Add_right(ptr);
 308
 309                         if (get_irn_mode(l) == get_irn_mode(ptr) && is_Const(r))
 310                                 ptr = l;
 311                         else if (get_irn_mode(r) == get_irn_mode(ptr) && is_Const(l))
 312                                 ptr = r;
 313                         else
 314                                 return NULL;
 315
 316                         /* for now, we support only one addition, reassoc should fold all others */
 317                         if (! is_SymConst(ptr) && !is_Sel(ptr))
 318                                 return NULL;
 319                 } else if (is_Sub(ptr)) {
 320                         ir_node *l = get_Sub_left(ptr);
 321                         ir_node *r = get_Sub_right(ptr);
 322
 323                         if (get_irn_mode(l) == get_irn_mode(ptr) &&     is_Const(r))
 324                                 ptr = l;
 325                         else
 326                                 return NULL;
 327                         /* for now, we support only one substraction, reassoc should fold all others */
 328                         if (! is_SymConst(ptr) && !is_Sel(ptr))
 329                                 return NULL;
 330                 } else
 331                         return NULL;
 332         }
 333 }  /* find_constant_entity */
 334
 335 /**
 336  * Return the Selection index of a Sel node from dimension n
 337  */
 338 static long get_Sel_array_index_long(ir_node *n, int dim)
 339 {
 340         ir_node *index = get_Sel_index(n, dim);
 341         assert(is_Const(index));
 342         return get_tarval_long(get_Const_tarval(index));
 343 }  /* get_Sel_array_index_long */
 344
 345 /**
 346  * Returns the accessed component graph path for an
 347  * node computing an address.
 348  *
 349  * @param ptr    the node computing the address
 350  * @param depth  current depth in steps upward from the root
 351  *               of the address
 352  */
 353 static compound_graph_path *rec_get_accessed_path(ir_node *ptr, int depth)
 354 {
 355         compound_graph_path *res = NULL;
 356         ir_entity           *root, *field, *ent;
 357         int                 path_len, pos, idx;
 358         tarval              *tv;
 359         ir_type             *tp;
 360
 361         if (is_SymConst(ptr)) {
 362                 /* a SymConst. If the depth is 0, this is an access to a global
 363                  * entity and we don't need a component path, else we know
 364                  * at least its length.
 365                  */
 366                 assert(get_SymConst_kind(ptr) == symconst_addr_ent);
 367                 root = get_SymConst_entity(ptr);
 368                 res = (depth == 0) ? NULL : new_compound_graph_path(get_entity_type(root), depth);
 369         } else if (is_Sel(ptr)) {
 370                 /* it's a Sel, go up until we find the root */
 371                 res = rec_get_accessed_path(get_Sel_ptr(ptr), depth+1);
 372                 if (res == NULL)
 373                         return NULL;
 374
 375                 /* fill up the step in the path at the current position */
 376                 field    = get_Sel_entity(ptr);
 377                 path_len = get_compound_graph_path_length(res);
 378                 pos      = path_len - depth - 1;
 379                 set_compound_graph_path_node(res, pos, field);
 380
 381                 if (is_Array_type(get_entity_owner(field))) {
 382                         assert(get_Sel_n_indexs(ptr) == 1 && "multi dim arrays not implemented");
 383                         set_compound_graph_path_array_index(res, pos, get_Sel_array_index_long(ptr, 0));
 384                 }
 385         } else if (is_Add(ptr)) {
 386                 ir_node *l    = get_Add_left(ptr);
 387                 ir_node *r    = get_Add_right(ptr);
 388                 ir_mode *mode = get_irn_mode(ptr);
 389                 tarval  *tmp;
 390
 391                 if (is_Const(r) && get_irn_mode(l) == mode) {
 392                         ptr = l;
 393                         tv  = get_Const_tarval(r);
 394                 } else {
 395                         ptr = r;
 396                         tv  = get_Const_tarval(l);
 397                 }
 398 ptr_arith:
 399                 mode = get_tarval_mode(tv);
 400                 tmp  = tv;
 401
 402                 /* ptr must be a Sel or a SymConst, this was checked in find_constant_entity() */
 403                 if (is_Sel(ptr)) {
 404                         field = get_Sel_entity(ptr);
 405                 } else {
 406                         field = get_SymConst_entity(ptr);
 407                 }
 408                 idx = 0;
 409                 for (ent = field;;) {
 410                         unsigned size;
 411                         tarval   *sz, *tv_index, *tlower, *tupper;
 412                         ir_node  *bound;
 413
 414                         tp = get_entity_type(ent);
 415                         if (! is_Array_type(tp))
 416                                 break;
 417                         ent = get_array_element_entity(tp);
 418                         size = get_type_size_bytes(get_entity_type(ent));
 419                         sz   = new_tarval_from_long(size, mode);
 420
 421                         tv_index = tarval_div(tmp, sz);
 422                         tmp      = tarval_mod(tmp, sz);
 423
 424                         if (tv_index == tarval_bad || tmp == tarval_bad)
 425                                 return NULL;
 426
 427                         assert(get_array_n_dimensions(tp) == 1 && "multiarrays not implemented");
 428                         bound  = get_array_lower_bound(tp, 0);
 429                         tlower = computed_value(bound);
 430                         bound  = get_array_upper_bound(tp, 0);
 431                         tupper = computed_value(bound);
 432
 433                         if (tlower == tarval_bad || tupper == tarval_bad)
 434                                 return NULL;
 435
 436                         if (tarval_cmp(tv_index, tlower) & pn_Cmp_Lt)
 437                                 return NULL;
 438                         if (tarval_cmp(tupper, tv_index) & pn_Cmp_Lt)
 439                                 return NULL;
 440
 441                         /* ok, bounds check finished */
 442                         ++idx;
 443                 }
 444                 if (! tarval_is_null(tmp)) {
 445                         /* access to some struct/union member */
 446                         return NULL;
 447                 }
 448
 449                 /* should be at least ONE array */
 450                 if (idx == 0)
 451                         return NULL;
 452
 453                 res = rec_get_accessed_path(ptr, depth + idx);
 454                 if (res == NULL)
 455                         return NULL;
 456
 457                 path_len = get_compound_graph_path_length(res);
 458                 pos      = path_len - depth - idx;
 459
 460                 for (ent = field;;) {
 461                         unsigned size;
 462                         tarval   *sz, *tv_index;
 463                         long     index;
 464
 465                         tp = get_entity_type(ent);
 466                         if (! is_Array_type(tp))
 467                                 break;
 468                         ent = get_array_element_entity(tp);
 469                         set_compound_graph_path_node(res, pos, ent);
 470
 471                         size = get_type_size_bytes(get_entity_type(ent));
 472                         sz   = new_tarval_from_long(size, mode);
 473
 474                         tv_index = tarval_div(tv, sz);
 475                         tv       = tarval_mod(tv, sz);
 476
 477                         /* worked above, should work again */
 478                         assert(tv_index != tarval_bad && tv != tarval_bad);
 479
 480                         /* bounds already checked above */
 481                         index = get_tarval_long(tv_index);
 482                         set_compound_graph_path_array_index(res, pos, index);
 483                         ++pos;
 484                 }
 485         } else if (is_Sub(ptr)) {
 486                 ir_node *l = get_Sub_left(ptr);
 487                 ir_node *r = get_Sub_right(ptr);
 488
 489                 ptr = l;
 490                 tv  = get_Const_tarval(r);
 491                 tv  = tarval_neg(tv);
 492                 goto ptr_arith;
 493         }
 494         return res;
 495 }  /* rec_get_accessed_path */
 496
 497 /**
 498  * Returns an access path or NULL.  The access path is only
 499  * valid, if the graph is in phase_high and _no_ address computation is used.
 500  */
 501 static compound_graph_path *get_accessed_path(ir_node *ptr)
 502 {
 503         compound_graph_path *gr = rec_get_accessed_path(ptr, 0);
 504         return gr;
 505 }  /* get_accessed_path */
 506
 507 typedef struct path_entry {
 508         ir_entity         *ent;
 509         struct path_entry *next;
 510         long              index;
 511 } path_entry;
 512
 513 static ir_node *rec_find_compound_ent_value(ir_node *ptr, path_entry *next)
 514 {
 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 >= (int) 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 {
 690         return rec_find_compound_ent_value(ptr, NULL);
 691 }
 692
 693 /* forward */
 694 static void reduce_adr_usage(ir_node *ptr);
 695
 696 /**
 697  * Update a Load that may have lost its users.
 698  */
 699 static void handle_load_update(ir_node *load)
 700 {
 701         ldst_info_t *info = get_irn_link(load);
 702
 703         /* do NOT touch volatile loads for now */
 704         if (get_Load_volatility(load) == volatility_is_volatile)
 705                 return;
 706
 707         if (! info->projs[pn_Load_res] && ! info->projs[pn_Load_X_except]) {
 708                 ir_node *ptr = get_Load_ptr(load);
 709                 ir_node *mem = get_Load_mem(load);
 710
 711                 /* a Load whose value is neither used nor exception checked, remove it */
 712                 exchange(info->projs[pn_Load_M], mem);
 713                 if (info->projs[pn_Load_X_regular])
 714                         exchange(info->projs[pn_Load_X_regular], new_r_Jmp(get_nodes_block(load)));
 715                 kill_node(load);
 716                 reduce_adr_usage(ptr);
 717         }
 718 }  /* handle_load_update */
 719
 720 /**
 721  * A use of an address node has vanished. Check if this was a Proj
 722  * node and update the counters.
 723  */
 724 static void reduce_adr_usage(ir_node *ptr)
 725 {
 726         ir_node *pred;
 727         if (!is_Proj(ptr))
 728                 return;
 729         if (get_irn_n_edges(ptr) > 0)
 730                 return;
 731
 732         /* this Proj is dead now */
 733         pred = get_Proj_pred(ptr);
 734         if (is_Load(pred)) {
 735                 ldst_info_t *info = get_irn_link(pred);
 736                 info->projs[get_Proj_proj(ptr)] = NULL;
 737
 738                 /* this node lost its result proj, handle that */
 739                 handle_load_update(pred);
 740         }
 741 }  /* reduce_adr_usage */
 742
 743 /**
 744  * Check, if an already existing value of mode old_mode can be converted
 745  * into the needed one new_mode without loss.
 746  */
 747 static int can_use_stored_value(ir_mode *old_mode, ir_mode *new_mode)
 748 {
 749         if (old_mode == new_mode)
 750                 return 1;
 751
 752         /* if both modes are two-complement ones, we can always convert the
 753            Stored value into the needed one. */
 754         if (get_mode_size_bits(old_mode) >= get_mode_size_bits(new_mode) &&
 755                   get_mode_arithmetic(old_mode) == irma_twos_complement &&
 756                   get_mode_arithmetic(new_mode) == irma_twos_complement)
 757                 return 1;
 758         return 0;
 759 }  /* can_use_stored_value */
 760
 761 /**
 762  * Check whether a Call is at least pure, ie. does only read memory.
 763  */
 764 static unsigned is_Call_pure(ir_node *call)
 765 {
 766         ir_type *call_tp = get_Call_type(call);
 767         unsigned prop = get_method_additional_properties(call_tp);
 768
 769         /* check first the call type */
 770         if ((prop & (mtp_property_const|mtp_property_pure)) == 0) {
 771                 /* try the called entity */
 772                 ir_node *ptr = get_Call_ptr(call);
 773
 774                 if (is_Global(ptr)) {
 775                         ir_entity *ent = get_Global_entity(ptr);
 776
 777                         prop = get_entity_additional_properties(ent);
 778                 }
 779         }
 780         return (prop & (mtp_property_const|mtp_property_pure)) != 0;
 781 }  /* is_Call_pure */
 782
 783 static ir_node *get_base_and_offset(ir_node *ptr, long *pOffset)
 784 {
 785         ir_mode *mode  = get_irn_mode(ptr);
 786         long    offset = 0;
 787
 788         /* TODO: long might not be enough, we should probably use some tarval thingy... */
 789         for (;;) {
 790                 if (is_Add(ptr)) {
 791                         ir_node *l = get_Add_left(ptr);
 792                         ir_node *r = get_Add_right(ptr);
 793
 794                         if (get_irn_mode(l) != mode || !is_Const(r))
 795                                 break;
 796
 797                         offset += get_tarval_long(get_Const_tarval(r));
 798                         ptr     = l;
 799                 } else if (is_Sub(ptr)) {
 800                         ir_node *l = get_Sub_left(ptr);
 801                         ir_node *r = get_Sub_right(ptr);
 802
 803                         if (get_irn_mode(l) != mode || !is_Const(r))
 804                                 break;
 805
 806                         offset -= get_tarval_long(get_Const_tarval(r));
 807                         ptr     = l;
 808                 } else if (is_Sel(ptr)) {
 809                         ir_entity *ent = get_Sel_entity(ptr);
 810                         ir_type   *tp  = get_entity_owner(ent);
 811
 812                         if (is_Array_type(tp)) {
 813                                 int     size;
 814                                 ir_node *index;
 815
 816                                 /* only one dimensional arrays yet */
 817                                 if (get_Sel_n_indexs(ptr) != 1)
 818                                         break;
 819                                 index = get_Sel_index(ptr, 0);
 820                                 if (! is_Const(index))
 821                                         break;
 822
 823                                 tp = get_entity_type(ent);
 824                                 if (get_type_state(tp) != layout_fixed)
 825                                         break;
 826
 827                                 size    = get_type_size_bytes(tp);
 828                                 offset += size * get_tarval_long(get_Const_tarval(index));
 829                         } else {
 830                                 if (get_type_state(tp) != layout_fixed)
 831                                         break;
 832                                 offset += get_entity_offset(ent);
 833                         }
 834                         ptr = get_Sel_ptr(ptr);
 835                 } else
 836                         break;
 837         }
 838
 839         *pOffset = offset;
 840         return ptr;
 841 }
 842
 843 static int try_load_after_store(ir_node *load,
 844                 ir_node *load_base_ptr, long load_offset, ir_node *store)
 845 {
 846         ldst_info_t *info;
 847         ir_node *store_ptr      = get_Store_ptr(store);
 848         long     store_offset;
 849         ir_node *store_base_ptr = get_base_and_offset(store_ptr, &store_offset);
 850         ir_node *store_value;
 851         ir_mode *store_mode;
 852         ir_node *load_ptr;
 853         ir_mode *load_mode;
 854         long     load_mode_len;
 855         long     store_mode_len;
 856         long     delta;
 857         int      res;
 858
 859         if (load_base_ptr != store_base_ptr)
 860                 return 0;
 861
 862         load_mode      = get_Load_mode(load);
 863         load_mode_len  = get_mode_size_bytes(load_mode);
 864         store_mode     = get_irn_mode(get_Store_value(store));
 865         store_mode_len = get_mode_size_bytes(store_mode);
 866         delta          = load_offset - store_offset;
 867         store_value    = get_Store_value(store);
 868
 869         if (delta != 0 || store_mode != load_mode) {
 870                 if (delta < 0 || delta + load_mode_len > store_mode_len)
 871                         return 0;
 872
 873                 if (get_mode_arithmetic(store_mode) != irma_twos_complement ||
 874                         get_mode_arithmetic(load_mode)  != irma_twos_complement)
 875                         return 0;
 876
 877
 878                 /* produce a shift to adjust offset delta */
 879                 if (delta > 0) {
 880                         ir_node *cnst;
 881
 882                         /* FIXME: only true for little endian */
 883                         cnst        = new_Const_long(mode_Iu, delta * 8);
 884                         store_value = new_r_Shr(get_nodes_block(load),
 885                                                                         store_value, cnst, store_mode);
 886                 }
 887
 888                 /* add an convert if needed */
 889                 if (store_mode != load_mode) {
 890                         store_value = new_r_Conv(get_nodes_block(load), store_value, load_mode);
 891                 }
 892         }
 893
 894         DBG_OPT_RAW(load, store_value);
 895
 896         info = get_irn_link(load);
 897         if (info->projs[pn_Load_M])
 898                 exchange(info->projs[pn_Load_M], get_Load_mem(load));
 899
 900         res = 0;
 901         /* no exception */
 902         if (info->projs[pn_Load_X_except]) {
 903                 exchange( info->projs[pn_Load_X_except], new_Bad());
 904                 res |= CF_CHANGED;
 905         }
 906         if (info->projs[pn_Load_X_regular]) {
 907                 exchange( info->projs[pn_Load_X_regular], new_r_Jmp(get_nodes_block(load)));
 908                 res |= CF_CHANGED;
 909         }
 910
 911         if (info->projs[pn_Load_res])
 912                 exchange(info->projs[pn_Load_res], store_value);
 913
 914         load_ptr = get_Load_ptr(load);
 915         kill_node(load);
 916         reduce_adr_usage(load_ptr);
 917         return res | DF_CHANGED;
 918 }
 919
 920 /**
 921  * Follow the memory chain as long as there are only Loads,
 922  * alias free Stores, and constant Calls and try to replace the
 923  * current Load by a previous ones.
 924  * Note that in unreachable loops it might happen that we reach
 925  * load again, as well as we can fall into a cycle.
 926  * We break such cycles using a special visited flag.
 927  *
 928  * INC_MASTER() must be called before dive into
 929  */
 930 static unsigned follow_Mem_chain(ir_node *load, ir_node *curr)
 931 {
 932         unsigned    res = 0;
 933         ldst_info_t *info = get_irn_link(load);
 934         ir_node     *pred;
 935         ir_node     *ptr       = get_Load_ptr(load);
 936         ir_node     *mem       = get_Load_mem(load);
 937         ir_mode     *load_mode = get_Load_mode(load);
 938
 939         for (pred = curr; load != pred; ) {
 940                 ldst_info_t *pred_info = get_irn_link(pred);
 941
 942                 /*
 943                  * a Load immediately after a Store -- a read after write.
 944                  * We may remove the Load, if both Load & Store does not have an
 945                  * exception handler OR they are in the same MacroBlock. In the latter
 946                  * case the Load cannot throw an exception when the previous Store was
 947                  * quiet.
 948                  *
 949                  * Why we need to check for Store Exception? If the Store cannot
 950                  * be executed (ROM) the exception handler might simply jump into
 951                  * the load MacroBlock :-(
 952                  * We could make it a little bit better if we would know that the
 953                  * exception handler of the Store jumps directly to the end...
 954                  */
 955                 if (is_Store(pred) && ((pred_info->projs[pn_Store_X_except] == NULL
 956                                 && info->projs[pn_Load_X_except] == NULL)
 957                                 || get_nodes_MacroBlock(load) == get_nodes_MacroBlock(pred)))
 958                 {
 959                         long    load_offset;
 960                         ir_node *base_ptr = get_base_and_offset(ptr, &load_offset);
 961                         int     changes   = try_load_after_store(load, base_ptr, load_offset, pred);
 962
 963                         if (changes != 0)
 964                                 return res | changes;
 965                 } else if (is_Load(pred) && get_Load_ptr(pred) == ptr &&
 966                            can_use_stored_value(get_Load_mode(pred), load_mode)) {
 967                         /*
 968                          * a Load after a Load -- a read after read.
 969                          * We may remove the second Load, if it does not have an exception handler
 970                          * OR they are in the same MacroBlock. In the later case the Load cannot
 971                          * throw an exception when the previous Load was quiet.
 972                          *
 973                          * Here, there is no need to check if the previous Load has an exception
 974                          * hander because they would have exact the same exception...
 975                          */
 976                         if (info->projs[pn_Load_X_except] == NULL || get_nodes_MacroBlock(load) == get_nodes_MacroBlock(pred)) {
 977                                 ir_node *value;
 978
 979                                 DBG_OPT_RAR(load, pred);
 980
 981                                 /* the result is used */
 982                                 if (info->projs[pn_Load_res]) {
 983                                         if (pred_info->projs[pn_Load_res] == NULL) {
 984                                                 /* create a new Proj again */
 985                                                 pred_info->projs[pn_Load_res] = new_r_Proj(pred, get_Load_mode(pred), pn_Load_res);
 986                                         }
 987                                         value = pred_info->projs[pn_Load_res];
 988
 989                                         /* add an convert if needed */
 990                                         if (get_Load_mode(pred) != load_mode) {
 991                                                 value = new_r_Conv(get_nodes_block(load), value, load_mode);
 992                                         }
 993
 994                                         exchange(info->projs[pn_Load_res], value);
 995                                 }
 996
 997                                 if (info->projs[pn_Load_M])
 998                                         exchange(info->projs[pn_Load_M], mem);
 999
1000                                 /* no exception */
1001                                 if (info->projs[pn_Load_X_except]) {
1002                                         exchange(info->projs[pn_Load_X_except], new_Bad());
1003                                         res |= CF_CHANGED;
1004                                 }
1005                                 if (info->projs[pn_Load_X_regular]) {
1006                                         exchange( info->projs[pn_Load_X_regular], new_r_Jmp(get_nodes_block(load)));
1007                                         res |= CF_CHANGED;
1008                                 }
1009
1010                                 kill_node(load);
1011                                 reduce_adr_usage(ptr);
1012                                 return res |= DF_CHANGED;
1013                         }
1014                 }
1015
1016                 if (is_Store(pred)) {
1017                         /* check if we can pass through this store */
1018                         ir_alias_relation rel = get_alias_relation(
1019                                 current_ir_graph,
1020                                 get_Store_ptr(pred),
1021                                 get_irn_mode(get_Store_value(pred)),
1022                                 ptr, load_mode);
1023                         /* if the might be an alias, we cannot pass this Store */
1024                         if (rel != ir_no_alias)
1025                                 break;
1026                         pred = skip_Proj(get_Store_mem(pred));
1027                 } else if (is_Load(pred)) {
1028                         pred = skip_Proj(get_Load_mem(pred));
1029                 } else if (is_Call(pred)) {
1030                         if (is_Call_pure(pred)) {
1031                                 /* The called graph is at least pure, so there are no Store's
1032                                    in it. We can handle it like a Load and skip it. */
1033                                 pred = skip_Proj(get_Call_mem(pred));
1034                         } else {
1035                                 /* there might be Store's in the graph, stop here */
1036                                 break;
1037                         }
1038                 } else {
1039                         /* follow only Load chains */
1040                         break;
1041                 }
1042
1043                 /* check for cycles */
1044                 if (NODE_VISITED(pred_info))
1045                         break;
1046                 MARK_NODE(pred_info);
1047         }
1048
1049         if (is_Sync(pred)) {
1050                 int i;
1051
1052                 /* handle all Sync predecessors */
1053                 for (i = get_Sync_n_preds(pred) - 1; i >= 0; --i) {
1054                         res |= follow_Mem_chain(load, skip_Proj(get_Sync_pred(pred, i)));
1055                         if (res)
1056                                 return res;
1057                 }
1058         }
1059
1060         return res;
1061 }  /* follow_Mem_chain */
1062
1063 /*
1064  * Check if we can replace the load by a given const from
1065  * the const code irg.
1066  */
1067 ir_node *can_replace_load_by_const(const ir_node *load, ir_node *c)
1068 {
1069         ir_mode *c_mode = get_irn_mode(c);
1070         ir_mode *l_mode = get_Load_mode(load);
1071         ir_node *res    = NULL;
1072
1073         if (c_mode != l_mode) {
1074                 /* check, if the mode matches OR can be easily converted info */
1075                 if (is_reinterpret_cast(c_mode, l_mode)) {
1076                         /* we can safely cast */
1077                         dbg_info *dbg   = get_irn_dbg_info(load);
1078                         ir_node  *block = get_nodes_block(load);
1079
1080                         /* copy the value from the const code irg and cast it */
1081                         res = copy_const_value(dbg, c);
1082                         res = new_rd_Conv(dbg, block, res, l_mode);
1083                 }
1084         } else {
1085                 /* copy the value from the const code irg */
1086                 res = copy_const_value(get_irn_dbg_info(load), c);
1087         }
1088         return res;
1089 }  /* can_replace_load_by_const */
1090
1091 /**
1092  * optimize a Load
1093  *
1094  * @param load  the Load node
1095  */
1096 static unsigned optimize_load(ir_node *load)
1097 {
1098         ldst_info_t *info = get_irn_link(load);
1099         ir_node     *mem, *ptr, *value;
1100         ir_entity   *ent;
1101         long        dummy;
1102         unsigned    res = 0;
1103
1104         /* do NOT touch volatile loads for now */
1105         if (get_Load_volatility(load) == volatility_is_volatile)
1106                 return 0;
1107
1108         /* the address of the load to be optimized */
1109         ptr = get_Load_ptr(load);
1110
1111         /* The mem of the Load. Must still be returned after optimization. */
1112         mem = get_Load_mem(load);
1113
1114         if (info->projs[pn_Load_res] == NULL
1115                         && info->projs[pn_Load_X_except] == NULL) {
1116                 /* the value is never used and we don't care about exceptions, remove */
1117                 exchange(info->projs[pn_Load_M], mem);
1118
1119                 if (info->projs[pn_Load_X_regular]) {
1120                         /* should not happen, but if it does, remove it */
1121                         exchange(info->projs[pn_Load_X_regular], new_r_Jmp(get_nodes_block(load)));
1122                         res |= CF_CHANGED;
1123                 }
1124                 kill_node(load);
1125                 reduce_adr_usage(ptr);
1126                 return res | DF_CHANGED;
1127         }
1128
1129         /* Load from a constant polymorphic field, where we can resolve
1130            polymorphism. */
1131         value = transform_polymorph_Load(load);
1132         if (value == load) {
1133                 value = NULL;
1134                 /* check if we can determine the entity that will be loaded */
1135                 ent = find_constant_entity(ptr);
1136                 if (ent != NULL
1137                                 && get_entity_visibility(ent) != ir_visibility_external) {
1138                         /* a static allocation that is not external: there should be NO
1139                          * exception when loading even if we cannot replace the load itself.
1140                          */
1141
1142                         /* no exception, clear the info field as it might be checked later again */
1143                         if (info->projs[pn_Load_X_except]) {
1144                                 exchange(info->projs[pn_Load_X_except], new_Bad());
1145                                 info->projs[pn_Load_X_except] = NULL;
1146                                 res |= CF_CHANGED;
1147                         }
1148                         if (info->projs[pn_Load_X_regular]) {
1149                                 exchange(info->projs[pn_Load_X_regular], new_r_Jmp(get_nodes_block(load)));
1150                                 info->projs[pn_Load_X_regular] = NULL;
1151                                 res |= CF_CHANGED;
1152                         }
1153
1154                         if (get_entity_linkage(ent) & IR_LINKAGE_CONSTANT) {
1155                                 if (ent->initializer != NULL) {
1156                                         /* new style initializer */
1157                                         value = find_compound_ent_value(ptr);
1158                                 } else if (entity_has_compound_ent_values(ent)) {
1159                                         /* old style initializer */
1160                                         compound_graph_path *path = get_accessed_path(ptr);
1161
1162                                         if (path != NULL) {
1163                                                 assert(is_proper_compound_graph_path(path, get_compound_graph_path_length(path)-1));
1164
1165                                                 value = get_compound_ent_value_by_path(ent, path);
1166                                                 DB((dbg, LEVEL_1, "  Constant access at %F%F resulted in %+F\n", ent, path, value));
1167                                                 free_compound_graph_path(path);
1168                                         }
1169                                 }
1170                                 if (value != NULL)
1171                                         value = can_replace_load_by_const(load, value);
1172                         }
1173                 }
1174         }
1175         if (value != NULL) {
1176                 /* we completely replace the load by this value */
1177                 if (info->projs[pn_Load_X_except]) {
1178                         exchange(info->projs[pn_Load_X_except], new_Bad());
1179                         info->projs[pn_Load_X_except] = NULL;
1180                         res |= CF_CHANGED;
1181                 }
1182                 if (info->projs[pn_Load_X_regular]) {
1183                         exchange(info->projs[pn_Load_X_regular], new_r_Jmp(get_nodes_block(load)));
1184                         info->projs[pn_Load_X_regular] = NULL;
1185                         res |= CF_CHANGED;
1186                 }
1187                 if (info->projs[pn_Load_M]) {
1188                         exchange(info->projs[pn_Load_M], mem);
1189                         res |= DF_CHANGED;
1190                 }
1191                 if (info->projs[pn_Load_res]) {
1192                         exchange(info->projs[pn_Load_res], value);
1193                         res |= DF_CHANGED;
1194                 }
1195                 kill_node(load);
1196                 reduce_adr_usage(ptr);
1197                 return res;
1198         }
1199
1200         /* Check, if the address of this load is used more than once.
1201          * If not, more load cannot be removed in any case. */
1202         if (get_irn_n_uses(ptr) <= 1 && get_irn_n_uses(get_base_and_offset(ptr, &dummy)) <= 1)
1203                 return res;
1204
1205         /*
1206          * follow the memory chain as long as there are only Loads
1207          * and try to replace current Load or Store by a previous one.
1208          * Note that in unreachable loops it might happen that we reach
1209          * load again, as well as we can fall into a cycle.
1210          * We break such cycles using a special visited flag.
1211          */
1212         INC_MASTER();
1213         res = follow_Mem_chain(load, skip_Proj(mem));
1214         return res;
1215 }  /* optimize_load */
1216
1217 /**
1218  * Check whether a value of mode new_mode would completely overwrite a value
1219  * of mode old_mode in memory.
1220  */
1221 static int is_completely_overwritten(ir_mode *old_mode, ir_mode *new_mode)
1222 {
1223         return get_mode_size_bits(new_mode) >= get_mode_size_bits(old_mode);
1224 }  /* is_completely_overwritten */
1225
1226 /**
1227  * Check whether small is a part of large (starting at same address).
1228  */
1229 static int is_partially_same(ir_node *small, ir_node *large)
1230 {
1231         ir_mode *sm = get_irn_mode(small);
1232         ir_mode *lm = get_irn_mode(large);
1233
1234         /* FIXME: Check endianness */
1235         return is_Conv(small) && get_Conv_op(small) == large
1236             && get_mode_size_bytes(sm) < get_mode_size_bytes(lm)
1237             && get_mode_arithmetic(sm) == irma_twos_complement
1238             && get_mode_arithmetic(lm) == irma_twos_complement;
1239 }  /* is_partially_same */
1240
1241 /**
1242  * follow the memory chain as long as there are only Loads and alias free Stores.
1243  *
1244  * INC_MASTER() must be called before dive into
1245  */
1246 static unsigned follow_Mem_chain_for_Store(ir_node *store, ir_node *curr)
1247 {
1248         unsigned res = 0;
1249         ldst_info_t *info = get_irn_link(store);
1250         ir_node *pred;
1251         ir_node *ptr = get_Store_ptr(store);
1252         ir_node *mem = get_Store_mem(store);
1253         ir_node *value = get_Store_value(store);
1254         ir_mode *mode  = get_irn_mode(value);
1255         ir_node *block = get_nodes_block(store);
1256         ir_node *mblk  = get_Block_MacroBlock(block);
1257
1258         for (pred = curr; pred != store;) {
1259                 ldst_info_t *pred_info = get_irn_link(pred);
1260
1261                 /*
1262                  * BEWARE: one might think that checking the modes is useless, because
1263                  * if the pointers are identical, they refer to the same object.
1264                  * This is only true in strong typed languages, not is C were the following
1265                  * is possible *(ir_type1 *)p = a; *(ir_type2 *)p = b ...
1266                  * However, if the size of the mode that is written is bigger or equal the
1267                  * size of the old one, the old value is completely overwritten and can be
1268                  * killed ...
1269                  */
1270                 if (is_Store(pred) && get_Store_ptr(pred) == ptr &&
1271             get_nodes_MacroBlock(pred) == mblk) {
1272                         /*
1273                          * a Store after a Store in the same MacroBlock -- a write after write.
1274                          */
1275
1276                         /*
1277                          * We may remove the first Store, if the old value is completely
1278                          * overwritten or the old value is a part of the new value,
1279                          * and if it does not have an exception handler.
1280                          *
1281                          * TODO: What, if both have the same exception handler ???
1282                          */
1283                         if (get_Store_volatility(pred) != volatility_is_volatile
1284                                 && !pred_info->projs[pn_Store_X_except]) {
1285                                 ir_node *predvalue = get_Store_value(pred);
1286                                 ir_mode *predmode  = get_irn_mode(predvalue);
1287
1288                                 if (is_completely_overwritten(predmode, mode)
1289                                         || is_partially_same(predvalue, value)) {
1290                                         DBG_OPT_WAW(pred, store);
1291                                         exchange(pred_info->projs[pn_Store_M], get_Store_mem(pred));
1292                                         kill_node(pred);
1293                                         reduce_adr_usage(ptr);
1294                                         return DF_CHANGED;
1295                                 }
1296                         }
1297
1298                         /*
1299                          * We may remove the Store, if the old value already contains
1300                          * the new value, and if it does not have an exception handler.
1301                          *
1302                          * TODO: What, if both have the same exception handler ???
1303                          */
1304                         if (get_Store_volatility(store) != volatility_is_volatile
1305                                 && !info->projs[pn_Store_X_except]) {
1306                                 ir_node *predvalue = get_Store_value(pred);
1307
1308                                 if (is_partially_same(value, predvalue)) {
1309                                         DBG_OPT_WAW(pred, store);
1310                                         exchange(info->projs[pn_Store_M], mem);
1311                                         kill_node(store);
1312                                         reduce_adr_usage(ptr);
1313                                         return DF_CHANGED;
1314                                 }
1315                         }
1316                 } else if (is_Load(pred) && get_Load_ptr(pred) == ptr &&
1317                            value == pred_info->projs[pn_Load_res]) {
1318                         /*
1319                          * a Store of a value just loaded from the same address
1320                          * -- a write after read.
1321                          * We may remove the Store, if it does not have an exception
1322                          * handler.
1323                          */
1324                         if (! info->projs[pn_Store_X_except]) {
1325                                 DBG_OPT_WAR(store, pred);
1326                                 exchange(info->projs[pn_Store_M], mem);
1327                                 kill_node(store);
1328                                 reduce_adr_usage(ptr);
1329                                 return DF_CHANGED;
1330                         }
1331                 }
1332
1333                 if (is_Store(pred)) {
1334                         /* check if we can pass through this store */
1335                         ir_alias_relation rel = get_alias_relation(
1336                                 current_ir_graph,
1337                                 get_Store_ptr(pred),
1338                                 get_irn_mode(get_Store_value(pred)),
1339                                 ptr, mode);
1340                         /* if the might be an alias, we cannot pass this Store */
1341                         if (rel != ir_no_alias)
1342                                 break;
1343                         pred = skip_Proj(get_Store_mem(pred));
1344                 } else if (is_Load(pred)) {
1345                         ir_alias_relation rel = get_alias_relation(
1346                                 current_ir_graph, get_Load_ptr(pred), get_Load_mode(pred),
1347                                 ptr, mode);
1348                         if (rel != ir_no_alias)
1349                                 break;
1350
1351                         pred = skip_Proj(get_Load_mem(pred));
1352                 } else {
1353                         /* follow only Load chains */
1354                         break;
1355                 }
1356
1357                 /* check for cycles */
1358                 if (NODE_VISITED(pred_info))
1359                         break;
1360                 MARK_NODE(pred_info);
1361         }
1362
1363         if (is_Sync(pred)) {
1364                 int i;
1365
1366                 /* handle all Sync predecessors */
1367                 for (i = get_Sync_n_preds(pred) - 1; i >= 0; --i) {
1368                         res |= follow_Mem_chain_for_Store(store, skip_Proj(get_Sync_pred(pred, i)));
1369                         if (res)
1370                                 break;
1371                 }
1372         }
1373         return res;
1374 }  /* follow_Mem_chain_for_Store */
1375
1376 /** find entity used as base for an address calculation */
1377 static ir_entity *find_entity(ir_node *ptr)
1378 {
1379         switch (get_irn_opcode(ptr)) {
1380         case iro_SymConst:
1381                 return get_SymConst_entity(ptr);
1382         case iro_Sel: {
1383                 ir_node *pred = get_Sel_ptr(ptr);
1384                 if (get_irg_frame(get_irn_irg(ptr)) == pred)
1385                         return get_Sel_entity(ptr);
1386
1387                 return find_entity(pred);
1388         }
1389         case iro_Sub:
1390         case iro_Add: {
1391                 ir_node *left = get_binop_left(ptr);
1392                 ir_node *right;
1393                 if (mode_is_reference(get_irn_mode(left)))
1394                         return find_entity(left);
1395                 right = get_binop_right(ptr);
1396                 if (mode_is_reference(get_irn_mode(right)))
1397                         return find_entity(right);
1398                 return NULL;
1399         }
1400         default:
1401                 return NULL;
1402         }
1403 }
1404
1405 /**
1406  * optimize a Store
1407  *
1408  * @param store  the Store node
1409  */
1410 static unsigned optimize_store(ir_node *store)
1411 {
1412         ir_node   *ptr;
1413         ir_node   *mem;
1414         ir_entity *entity;
1415
1416         if (get_Store_volatility(store) == volatility_is_volatile)
1417                 return 0;
1418
1419         ptr    = get_Store_ptr(store);
1420         entity = find_entity(ptr);
1421
1422         /* a store to an entity which is never read is unnecessary */
1423         if (entity != NULL && !(get_entity_usage(entity) & ir_usage_read)) {
1424                 ldst_info_t *info = get_irn_link(store);
1425                 if (info->projs[pn_Store_X_except] == NULL) {
1426                         DB((dbg, LEVEL_1, "  Killing useless %+F to never read entity %+F\n", store, entity));
1427                         exchange(info->projs[pn_Store_M], get_Store_mem(store));
1428                         kill_node(store);
1429                         reduce_adr_usage(ptr);
1430                         return DF_CHANGED;
1431                 }
1432         }
1433
1434         /* Check, if the address of this Store is used more than once.
1435          * If not, this Store cannot be removed in any case. */
1436         if (get_irn_n_uses(ptr) <= 1)
1437                 return 0;
1438
1439         mem = get_Store_mem(store);
1440
1441         /* follow the memory chain as long as there are only Loads */
1442         INC_MASTER();
1443
1444         return follow_Mem_chain_for_Store(store, skip_Proj(mem));
1445 }  /* optimize_store */
1446
1447 /**
1448  * walker, optimizes Phi after Stores to identical places:
1449  * Does the following optimization:
1450  * @verbatim
1451  *
1452  *   val1   val2   val3          val1  val2  val3
1453  *    |      |      |               \    |    /
1454  *  Store  Store  Store              \   |   /
1455  *      \    |    /                   PhiData
1456  *       \   |   /                       |
1457  *        \  |  /                      Store
1458  *          PhiM
1459  *
1460  * @endverbatim
1461  * This reduces the number of stores and allows for predicated execution.
1462  * Moves Stores back to the end of a function which may be bad.
1463  *
1464  * This is only possible if the predecessor blocks have only one successor.
1465  */
1466 static unsigned optimize_phi(ir_node *phi, walk_env_t *wenv)
1467 {
1468         int i, n;
1469         ir_node *store, *old_store, *ptr, *block, *phi_block, *phiM, *phiD, *exc, *projM;
1470         ir_mode *mode;
1471         ir_node **inM, **inD, **projMs;
1472         int *idx;
1473         dbg_info *db = NULL;
1474         ldst_info_t *info;
1475         block_info_t *bl_info;
1476         unsigned res = 0;
1477
1478         /* Must be a memory Phi */
1479         if (get_irn_mode(phi) != mode_M)
1480                 return 0;
1481
1482         n = get_Phi_n_preds(phi);
1483         if (n <= 0)
1484                 return 0;
1485
1486         /* must be only one user */
1487         projM = get_Phi_pred(phi, 0);
1488         if (get_irn_n_edges(projM) != 1)
1489                 return 0;
1490
1491         store = skip_Proj(projM);
1492         old_store = store;
1493         if (!is_Store(store))
1494                 return 0;
1495
1496         block = get_nodes_block(store);
1497
1498         /* abort on dead blocks */
1499         if (is_Block_dead(block))
1500                 return 0;
1501
1502         /* check if the block is post dominated by Phi-block
1503            and has no exception exit */
1504         bl_info = get_irn_link(block);
1505         if (bl_info->flags & BLOCK_HAS_EXC)
1506                 return 0;
1507
1508         phi_block = get_nodes_block(phi);
1509         if (! block_strictly_postdominates(phi_block, block))
1510                 return 0;
1511
1512         /* this is the address of the store */
1513         ptr  = get_Store_ptr(store);
1514         mode = get_irn_mode(get_Store_value(store));
1515         info = get_irn_link(store);
1516         exc  = info->exc_block;
1517
1518         for (i = 1; i < n; ++i) {
1519                 ir_node *pred = get_Phi_pred(phi, i);
1520
1521                 if (get_irn_n_edges(pred) != 1)
1522                         return 0;
1523
1524                 pred = skip_Proj(pred);
1525                 if (!is_Store(pred))
1526                         return 0;
1527
1528                 if (ptr != get_Store_ptr(pred) || mode != get_irn_mode(get_Store_value(pred)))
1529                         return 0;
1530
1531                 info = get_irn_link(pred);
1532
1533                 /* check, if all stores have the same exception flow */
1534                 if (exc != info->exc_block)
1535                         return 0;
1536
1537                 /* abort on dead blocks */
1538                 block = get_nodes_block(pred);
1539                 if (is_Block_dead(block))
1540                         return 0;
1541
1542                 /* check if the block is post dominated by Phi-block
1543                    and has no exception exit. Note that block must be different from
1544                    Phi-block, else we would move a Store from end End of a block to its
1545                    Start... */
1546                 bl_info = get_irn_link(block);
1547                 if (bl_info->flags & BLOCK_HAS_EXC)
1548                         return 0;
1549                 if (block == phi_block || ! block_postdominates(phi_block, block))
1550                         return 0;
1551         }
1552
1553         /*
1554          * ok, when we are here, we found all predecessors of a Phi that
1555          * are Stores to the same address and size. That means whatever
1556          * we do before we enter the block of the Phi, we do a Store.
1557          * So, we can move the Store to the current block:
1558          *
1559          *   val1    val2    val3          val1  val2  val3
1560          *    |       |       |               \    |    /
1561          * | Str | | Str | | Str |             \   |   /
1562          *      \     |     /                   PhiData
1563          *       \    |    /                       |
1564          *        \   |   /                       Str
1565          *           PhiM
1566          *
1567          * Is only allowed if the predecessor blocks have only one successor.
1568          */
1569
1570         NEW_ARR_A(ir_node *, projMs, n);
1571         NEW_ARR_A(ir_node *, inM, n);
1572         NEW_ARR_A(ir_node *, inD, n);
1573         NEW_ARR_A(int, idx, n);
1574
1575         /* Prepare: Collect all Store nodes.  We must do this
1576            first because we otherwise may loose a store when exchanging its
1577            memory Proj.
1578          */
1579         for (i = n - 1; i >= 0; --i) {
1580                 ir_node *store;
1581
1582                 projMs[i] = get_Phi_pred(phi, i);
1583                 assert(is_Proj(projMs[i]));
1584
1585                 store = get_Proj_pred(projMs[i]);
1586                 info  = get_irn_link(store);
1587
1588                 inM[i] = get_Store_mem(store);
1589                 inD[i] = get_Store_value(store);
1590                 idx[i] = info->exc_idx;
1591         }
1592         block = get_nodes_block(phi);
1593
1594         /* second step: create a new memory Phi */
1595         phiM = new_rd_Phi(get_irn_dbg_info(phi), block, n, inM, mode_M);
1596
1597         /* third step: create a new data Phi */
1598         phiD = new_rd_Phi(get_irn_dbg_info(phi), block, n, inD, mode);
1599
1600         /* rewire memory and kill the node */
1601         for (i = n - 1; i >= 0; --i) {
1602                 ir_node *proj  = projMs[i];
1603
1604                 if (is_Proj(proj)) {
1605                         ir_node *store = get_Proj_pred(proj);
1606                         exchange(proj, inM[i]);
1607                         kill_node(store);
1608                 }
1609         }
1610
1611         /* fourth step: create the Store */
1612         store = new_rd_Store(db, block, phiM, ptr, phiD, 0);
1613 #ifdef DO_CACHEOPT
1614         co_set_irn_name(store, co_get_irn_ident(old_store));
1615 #endif
1616
1617         projM = new_rd_Proj(NULL, store, mode_M, pn_Store_M);
1618
1619         info = get_ldst_info(store, &wenv->obst);
1620         info->projs[pn_Store_M] = projM;
1621
1622         /* fifths step: repair exception flow */
1623         if (exc) {
1624                 ir_node *projX = new_rd_Proj(NULL, store, mode_X, pn_Store_X_except);
1625
1626                 info->projs[pn_Store_X_except] = projX;
1627                 info->exc_block                = exc;
1628                 info->exc_idx                  = idx[0];
1629
1630                 for (i = 0; i < n; ++i) {
1631                         set_Block_cfgpred(exc, idx[i], projX);
1632                 }
1633
1634                 if (n > 1) {
1635                         /* the exception block should be optimized as some inputs are identical now */
1636                 }
1637
1638                 res |= CF_CHANGED;
1639         }
1640
1641         /* sixth step: replace old Phi */
1642         exchange(phi, projM);
1643
1644         return res | DF_CHANGED;
1645 }  /* optimize_phi */
1646
1647 /**
1648  * walker, do the optimizations
1649  */
1650 static void do_load_store_optimize(ir_node *n, void *env)
1651 {
1652         walk_env_t *wenv = env;
1653
1654         switch (get_irn_opcode(n)) {
1655
1656         case iro_Load:
1657                 wenv->changes |= optimize_load(n);
1658                 break;
1659
1660         case iro_Store:
1661                 wenv->changes |= optimize_store(n);
1662                 break;
1663
1664         case iro_Phi:
1665                 wenv->changes |= optimize_phi(n, wenv);
1666                 break;
1667
1668         default:
1669                 ;
1670         }
1671 }  /* do_load_store_optimize */
1672
1673 /** A scc. */
1674 typedef struct scc {
1675         ir_node *head;          /**< the head of the list */
1676 } scc;
1677
1678 /** A node entry. */
1679 typedef struct node_entry {
1680         unsigned DFSnum;    /**< the DFS number of this node */
1681         unsigned low;       /**< the low number of this node */
1682         int      in_stack;  /**< flag, set if the node is on the stack */
1683         ir_node  *next;     /**< link to the next node the the same scc */
1684         scc      *pscc;     /**< the scc of this node */
1685         unsigned POnum;     /**< the post order number for blocks */
1686 } node_entry;
1687
1688 /** A loop entry. */
1689 typedef struct loop_env {
1690         ir_phase ph;           /**< the phase object */
1691         ir_node  **stack;      /**< the node stack */
1692         int      tos;          /**< tos index */
1693         unsigned nextDFSnum;   /**< the current DFS number */
1694         unsigned POnum;        /**< current post order number */
1695
1696         unsigned changes;      /**< a bitmask of graph changes */
1697 } loop_env;
1698
1699 /**
1700 * Gets the node_entry of a node
1701 */
1702 static node_entry *get_irn_ne(ir_node *irn, loop_env *env)
1703 {
1704         ir_phase   *ph = &env->ph;
1705         node_entry *e  = phase_get_irn_data(&env->ph, irn);
1706
1707         if (! e) {
1708                 e = phase_alloc(ph, sizeof(*e));
1709                 memset(e, 0, sizeof(*e));
1710                 phase_set_irn_data(ph, irn, e);
1711         }
1712         return e;
1713 }  /* get_irn_ne */
1714
1715 /**
1716  * Push a node onto the stack.
1717  *
1718  * @param env   the loop environment
1719  * @param n     the node to push
1720  */
1721 static void push(loop_env *env, ir_node *n)
1722 {
1723         node_entry *e;
1724
1725         if (env->tos == ARR_LEN(env->stack)) {
1726                 int nlen = ARR_LEN(env->stack) * 2;
1727                 ARR_RESIZE(ir_node *, env->stack, nlen);
1728         }
1729         env->stack[env->tos++] = n;
1730         e = get_irn_ne(n, env);
1731         e->in_stack = 1;
1732 }  /* push */
1733
1734 /**
1735  * pop a node from the stack
1736  *
1737  * @param env   the loop environment
1738  *
1739  * @return  The topmost node
1740  */
1741 static ir_node *pop(loop_env *env)
1742 {
1743         ir_node *n = env->stack[--env->tos];
1744         node_entry *e = get_irn_ne(n, env);
1745
1746         e->in_stack = 0;
1747         return n;
1748 }  /* pop */
1749
1750 /**
1751  * Check if irn is a region constant.
1752  * The block or irn must strictly dominate the header block.
1753  *
1754  * @param irn           the node to check
1755  * @param header_block  the header block of the induction variable
1756  */
1757 static int is_rc(ir_node *irn, ir_node *header_block)
1758 {
1759         ir_node *block = get_nodes_block(irn);
1760
1761         return (block != header_block) && block_dominates(block, header_block);
1762 }  /* is_rc */
1763
1764 typedef struct phi_entry phi_entry;
1765 struct phi_entry {
1766         ir_node   *phi;    /**< A phi with a region const memory. */
1767         int       pos;     /**< The position of the region const memory */
1768         ir_node   *load;   /**< the newly created load for this phi */
1769         phi_entry *next;
1770 };
1771
1772 /**
1773  * An entry in the avail set.
1774  */
1775 typedef struct avail_entry_t {
1776         ir_node *ptr;   /**< the address pointer */
1777         ir_mode *mode;  /**< the load mode */
1778         ir_node *load;  /**< the associated Load */
1779 } avail_entry_t;
1780
1781 /**
1782  * Compare two avail entries.
1783  */
1784 static int cmp_avail_entry(const void *elt, const void *key, size_t size)
1785 {
1786         const avail_entry_t *a = elt;
1787         const avail_entry_t *b = key;
1788         (void) size;
1789
1790         return a->ptr != b->ptr || a->mode != b->mode;
1791 }  /* cmp_avail_entry */
1792
1793 /**
1794  * Calculate the hash value of an avail entry.
1795  */
1796 static unsigned hash_cache_entry(const avail_entry_t *entry)
1797 {
1798         return get_irn_idx(entry->ptr) * 9 + HASH_PTR(entry->mode);
1799 }  /* hash_cache_entry */
1800
1801 /**
1802  * Move loops out of loops if possible.
1803  *
1804  * @param pscc   the loop described by an SCC
1805  * @param env    the loop environment
1806  */
1807 static void move_loads_out_of_loops(scc *pscc, loop_env *env)
1808 {
1809         ir_node   *phi, *load, *next, *other, *next_other;
1810         ir_entity *ent;
1811         int       j;
1812         phi_entry *phi_list = NULL;
1813         set       *avail;
1814
1815         avail = new_set(cmp_avail_entry, 8);
1816
1817         /* collect all outer memories */
1818         for (phi = pscc->head; phi != NULL; phi = next) {
1819                 node_entry *ne = get_irn_ne(phi, env);
1820                 next = ne->next;
1821
1822                 /* check all memory Phi's */
1823                 if (! is_Phi(phi))
1824                         continue;
1825
1826                 assert(get_irn_mode(phi) == mode_M && "DFS return non-memory Phi");
1827
1828                 for (j = get_irn_arity(phi) - 1; j >= 0; --j) {
1829                         ir_node    *pred = get_irn_n(phi, j);
1830                         node_entry *pe   = get_irn_ne(pred, env);
1831
1832                         if (pe->pscc != ne->pscc) {
1833                                 /* not in the same SCC, is region const */
1834                                 phi_entry *pe = phase_alloc(&env->ph, sizeof(*pe));
1835
1836                                 pe->phi  = phi;
1837                                 pe->pos  = j;
1838                                 pe->next = phi_list;
1839                                 phi_list = pe;
1840                         }
1841                 }
1842         }
1843         /* no Phis no fun */
1844         assert(phi_list != NULL && "DFS found a loop without Phi");
1845
1846         /* for now, we cannot handle more than one input (only reducible cf) */
1847         if (phi_list->next != NULL)
1848                 return;
1849
1850         for (load = pscc->head; load; load = next) {
1851                 ir_mode *load_mode;
1852                 node_entry *ne = get_irn_ne(load, env);
1853                 next = ne->next;
1854
1855                 if (is_Load(load)) {
1856                         ldst_info_t *info = get_irn_link(load);
1857                         ir_node     *ptr = get_Load_ptr(load);
1858
1859                         /* for now, we cannot handle Loads with exceptions */
1860                         if (info->projs[pn_Load_res] == NULL || info->projs[pn_Load_X_regular] != NULL || info->projs[pn_Load_X_except] != NULL)
1861                                 continue;
1862
1863                         /* for now, we can only move Load(Global) */
1864                         if (! is_Global(ptr))
1865                                 continue;
1866                         ent       = get_Global_entity(ptr);
1867                         load_mode = get_Load_mode(load);
1868                         for (other = pscc->head; other != NULL; other = next_other) {
1869                                 node_entry *ne = get_irn_ne(other, env);
1870                                 next_other = ne->next;
1871
1872                                 if (is_Store(other)) {
1873                                         ir_alias_relation rel = get_alias_relation(
1874                                                 current_ir_graph,
1875                                                 get_Store_ptr(other),
1876                                                 get_irn_mode(get_Store_value(other)),
1877                                                 ptr, load_mode);
1878                                         /* if the might be an alias, we cannot pass this Store */
1879                                         if (rel != ir_no_alias)
1880                                                 break;
1881                                 }
1882                                 /* only Phis and pure Calls are allowed here, so ignore them */
1883                         }
1884                         if (other == NULL) {
1885                                 ldst_info_t *ninfo = NULL;
1886                                 phi_entry   *pe;
1887                                 dbg_info    *db;
1888
1889                                 /* yep, no aliasing Store found, Load can be moved */
1890                                 DB((dbg, LEVEL_1, "  Found a Load that could be moved: %+F\n", load));
1891
1892                                 db   = get_irn_dbg_info(load);
1893                                 for (pe = phi_list; pe != NULL; pe = pe->next) {
1894                                         int     pos   = pe->pos;
1895                                         ir_node *phi  = pe->phi;
1896                                         ir_node *blk  = get_nodes_block(phi);
1897                                         ir_node *pred = get_Block_cfgpred_block(blk, pos);
1898                                         ir_node *irn, *mem;
1899                                         avail_entry_t entry, *res;
1900
1901                                         entry.ptr  = ptr;
1902                                         entry.mode = load_mode;
1903                                         res = set_find(avail, &entry, sizeof(entry), hash_cache_entry(&entry));
1904                                         if (res != NULL) {
1905                                                 irn = res->load;
1906                                         } else {
1907                                                 irn = new_rd_Load(db, pred, get_Phi_pred(phi, pos), ptr, load_mode, 0);
1908                                                 entry.load = irn;
1909                                                 set_insert(avail, &entry, sizeof(entry), hash_cache_entry(&entry));
1910                                                 DB((dbg, LEVEL_1, "  Created %+F in %+F\n", irn, pred));
1911                                         }
1912                                         pe->load = irn;
1913                                         ninfo = get_ldst_info(irn, phase_obst(&env->ph));
1914
1915                                         ninfo->projs[pn_Load_M] = mem = new_r_Proj(irn, mode_M, pn_Load_M);
1916                                         set_Phi_pred(phi, pos, mem);
1917
1918                                         ninfo->projs[pn_Load_res] = new_r_Proj(irn, load_mode, pn_Load_res);
1919                                 }
1920
1921                                 /* now kill the old Load */
1922                                 exchange(info->projs[pn_Load_M], get_Load_mem(load));
1923                                 exchange(info->projs[pn_Load_res], ninfo->projs[pn_Load_res]);
1924
1925                                 env->changes |= DF_CHANGED;
1926                         }
1927                 }
1928         }
1929         del_set(avail);
1930 }  /* move_loads_out_of_loops */
1931
1932 /**
1933  * Process a loop SCC.
1934  *
1935  * @param pscc  the SCC
1936  * @param env   the loop environment
1937  */
1938 static void process_loop(scc *pscc, loop_env *env)
1939 {
1940         ir_node *irn, *next, *header = NULL;
1941         node_entry *b, *h = NULL;
1942         int j, only_phi, num_outside, process = 0;
1943         ir_node *out_rc;
1944
1945         /* find the header block for this scc */
1946         for (irn = pscc->head; irn; irn = next) {
1947                 node_entry *e = get_irn_ne(irn, env);
1948                 ir_node *block = get_nodes_block(irn);
1949
1950                 next = e->next;
1951                 b = get_irn_ne(block, env);
1952
1953                 if (header != NULL) {
1954                         if (h->POnum < b->POnum) {
1955                                 header = block;
1956                                 h      = b;
1957                         }
1958                 } else {
1959                         header = block;
1960                         h      = b;
1961                 }
1962         }
1963
1964         /* check if this scc contains only Phi, Loads or Stores nodes */
1965         only_phi    = 1;
1966         num_outside = 0;
1967         out_rc      = NULL;
1968         for (irn = pscc->head; irn; irn = next) {
1969                 node_entry *e = get_irn_ne(irn, env);
1970
1971                 next = e->next;
1972                 switch (get_irn_opcode(irn)) {
1973                 case iro_Call:
1974                         if (is_Call_pure(irn)) {
1975                                 /* pure calls can be treated like loads */
1976                                 only_phi = 0;
1977                                 break;
1978                         }
1979                         /* non-pure calls must be handle like may-alias Stores */
1980                         goto fail;
1981                 case iro_CopyB:
1982                         /* cannot handle CopyB yet */
1983                         goto fail;
1984                 case iro_Load:
1985                         process = 1;
1986                         if (get_Load_volatility(irn) == volatility_is_volatile) {
1987                                 /* cannot handle loops with volatile Loads */
1988                                 goto fail;
1989                         }
1990                         only_phi = 0;
1991                         break;
1992                 case iro_Store:
1993                         if (get_Store_volatility(irn) == volatility_is_volatile) {
1994                                 /* cannot handle loops with volatile Stores */
1995                                 goto fail;
1996                         }
1997                         only_phi = 0;
1998                         break;
1999                 default:
2000                         only_phi = 0;
2001                         break;
2002                 case iro_Phi:
2003                         for (j = get_irn_arity(irn) - 1; j >= 0; --j) {
2004                                 ir_node *pred  = get_irn_n(irn, j);
2005                                 node_entry *pe = get_irn_ne(pred, env);
2006
2007                                 if (pe->pscc != e->pscc) {
2008                                         /* not in the same SCC, must be a region const */
2009                                         if (! is_rc(pred, header)) {
2010                                                 /* not a memory loop */
2011                                                 goto fail;
2012                                         }
2013                                         if (out_rc == NULL) {
2014                                                 /* first region constant */
2015                                                 out_rc = pred;
2016                                                 ++num_outside;
2017                                         } else if (out_rc != pred) {
2018                                                 /* another region constant */
2019                                                 ++num_outside;
2020                                         }
2021                                 }
2022                         }
2023                         break;
2024                 }
2025         }
2026         if (! process)
2027                 goto fail;
2028
2029         /* found a memory loop */
2030         DB((dbg, LEVEL_2, "  Found a memory loop:\n  "));
2031         if (only_phi && num_outside == 1) {
2032                 /* a phi cycle with only one real predecessor can be collapsed */
2033                 DB((dbg, LEVEL_2, "  Found an USELESS Phi cycle:\n  "));
2034
2035                 for (irn = pscc->head; irn; irn = next) {
2036                         node_entry *e = get_irn_ne(irn, env);
2037                         next = e->next;
2038                         exchange(irn, out_rc);
2039                 }
2040                 env->changes |= DF_CHANGED;
2041                 return;
2042         }
2043
2044 #ifdef DEBUG_libfirm
2045         for (irn = pscc->head; irn; irn = next) {
2046                 node_entry *e = get_irn_ne(irn, env);
2047                 next = e->next;
2048                 DB((dbg, LEVEL_2, " %+F,", irn));
2049         }
2050         DB((dbg, LEVEL_2, "\n"));
2051 #endif
2052         move_loads_out_of_loops(pscc, env);
2053
2054 fail:
2055         ;
2056 }  /* process_loop */
2057
2058 /**
2059  * Process a SCC.
2060  *
2061  * @param pscc  the SCC
2062  * @param env   the loop environment
2063  */
2064 static void process_scc(scc *pscc, loop_env *env)
2065 {
2066         ir_node *head = pscc->head;
2067         node_entry *e = get_irn_ne(head, env);
2068
2069 #ifdef DEBUG_libfirm
2070         {
2071                 ir_node *irn, *next;
2072
2073                 DB((dbg, LEVEL_4, " SCC at %p:\n ", pscc));
2074                 for (irn = pscc->head; irn; irn = next) {
2075                         node_entry *e = get_irn_ne(irn, env);
2076
2077                         next = e->next;
2078
2079                         DB((dbg, LEVEL_4, " %+F,", irn));
2080                 }
2081                 DB((dbg, LEVEL_4, "\n"));
2082         }
2083 #endif
2084
2085         if (e->next != NULL) {
2086                 /* this SCC has more than one member */
2087                 process_loop(pscc, env);
2088         }
2089 }  /* process_scc */
2090
2091 /**
2092  * Do Tarjan's SCC algorithm and drive load/store optimization.
2093  *
2094  * @param irn  start at this node
2095  * @param env  the loop environment
2096  */
2097 static void dfs(ir_node *irn, loop_env *env)
2098 {
2099         int i, n;
2100         node_entry *node = get_irn_ne(irn, env);
2101
2102         mark_irn_visited(irn);
2103
2104         node->DFSnum = env->nextDFSnum++;
2105         node->low    = node->DFSnum;
2106         push(env, irn);
2107
2108         /* handle preds */
2109         if (is_Phi(irn) || is_Sync(irn)) {
2110                 n = get_irn_arity(irn);
2111                 for (i = 0; i < n; ++i) {
2112                         ir_node *pred = get_irn_n(irn, i);
2113                         node_entry *o = get_irn_ne(pred, env);
2114
2115                         if (!irn_visited(pred)) {
2116                                 dfs(pred, env);
2117                                 node->low = MIN(node->low, o->low);
2118                         }
2119                         if (o->DFSnum < node->DFSnum && o->in_stack)
2120                                 node->low = MIN(o->DFSnum, node->low);
2121                 }
2122         } else if (is_fragile_op(irn)) {
2123                 ir_node *pred = get_fragile_op_mem(irn);
2124                 node_entry *o = get_irn_ne(pred, env);
2125
2126                 if (!irn_visited(pred)) {
2127                         dfs(pred, env);
2128                         node->low = MIN(node->low, o->low);
2129                 }
2130                 if (o->DFSnum < node->DFSnum && o->in_stack)
2131                         node->low = MIN(o->DFSnum, node->low);
2132         } else if (is_Proj(irn)) {
2133                 ir_node *pred = get_Proj_pred(irn);
2134                 node_entry *o = get_irn_ne(pred, env);
2135
2136                 if (!irn_visited(pred)) {
2137                         dfs(pred, env);
2138                         node->low = MIN(node->low, o->low);
2139                 }
2140                 if (o->DFSnum < node->DFSnum && o->in_stack)
2141                         node->low = MIN(o->DFSnum, node->low);
2142         }
2143         else {
2144                  /* IGNORE predecessors */
2145         }
2146
2147         if (node->low == node->DFSnum) {
2148                 scc *pscc = phase_alloc(&env->ph, sizeof(*pscc));
2149                 ir_node *x;
2150
2151                 pscc->head = NULL;
2152                 do {
2153                         node_entry *e;
2154
2155                         x = pop(env);
2156                         e = get_irn_ne(x, env);
2157                         e->pscc    = pscc;
2158                         e->next    = pscc->head;
2159                         pscc->head = x;
2160                 } while (x != irn);
2161
2162                 process_scc(pscc, env);
2163         }
2164 }  /* dfs */
2165
2166 /**
2167  * Do the DFS on the memory edges a graph.
2168  *
2169  * @param irg  the graph to process
2170  * @param env  the loop environment
2171  */
2172 static void do_dfs(ir_graph *irg, loop_env *env)
2173 {
2174         ir_graph *rem = current_ir_graph;
2175         ir_node  *endblk, *end;
2176         int      i;
2177
2178         current_ir_graph = irg;
2179         inc_irg_visited(irg);
2180
2181         /* visit all memory nodes */
2182         endblk = get_irg_end_block(irg);
2183         for (i = get_Block_n_cfgpreds(endblk) - 1; i >= 0; --i) {
2184                 ir_node *pred = get_Block_cfgpred(endblk, i);
2185
2186                 pred = skip_Proj(pred);
2187                 if (is_Return(pred))
2188                         dfs(get_Return_mem(pred), env);
2189                 else if (is_Raise(pred))
2190                         dfs(get_Raise_mem(pred), env);
2191                 else if (is_fragile_op(pred))
2192                         dfs(get_fragile_op_mem(pred), env);
2193                 else {
2194                         assert(0 && "Unknown EndBlock predecessor");
2195                 }
2196         }
2197
2198         /* visit the keep-alives */
2199         end = get_irg_end(irg);
2200         for (i = get_End_n_keepalives(end) - 1; i >= 0; --i) {
2201                 ir_node *ka = get_End_keepalive(end, i);
2202
2203                 if (is_Phi(ka) && !irn_visited(ka))
2204                         dfs(ka, env);
2205         }
2206         current_ir_graph = rem;
2207 }  /* do_dfs */
2208
2209 /**
2210  * Initialize new phase data. We do this always explicit, so return NULL here
2211  */
2212 static void *init_loop_data(ir_phase *ph, const ir_node *irn, void *data)
2213 {
2214         (void)ph;
2215         (void)irn;
2216         (void)data;
2217         return NULL;
2218 }  /* init_loop_data */
2219
2220 /**
2221  * Optimize Loads/Stores in loops.
2222  *
2223  * @param irg  the graph
2224  */
2225 static int optimize_loops(ir_graph *irg)
2226 {
2227         loop_env env;
2228
2229         env.stack         = NEW_ARR_F(ir_node *, 128);
2230         env.tos           = 0;
2231         env.nextDFSnum    = 0;
2232         env.POnum         = 0;
2233         env.changes       = 0;
2234         phase_init(&env.ph, irg, init_loop_data);
2235
2236         /* calculate the SCC's and drive loop optimization. */
2237         do_dfs(irg, &env);
2238
2239         DEL_ARR_F(env.stack);
2240         phase_deinit(&env.ph);
2241
2242         return env.changes;
2243 }  /* optimize_loops */
2244
2245 /*
2246  * do the load store optimization
2247  */
2248 int optimize_load_store(ir_graph *irg)
2249 {
2250         walk_env_t env;
2251
2252         FIRM_DBG_REGISTER(dbg, "firm.opt.ldstopt");
2253
2254         assert(get_irg_phase_state(irg) != phase_building);
2255         assert(get_irg_pinned(irg) != op_pin_state_floats &&
2256                 "LoadStore optimization needs pinned graph");
2257
2258         /* we need landing pads */
2259         remove_critical_cf_edges(irg);
2260
2261         edges_assure(irg);
2262
2263         /* for Phi optimization post-dominators are needed ... */
2264         assure_postdoms(irg);
2265
2266         if (get_opt_alias_analysis()) {
2267                 assure_irg_entity_usage_computed(irg);
2268                 assure_irp_globals_entity_usage_computed();
2269         }
2270
2271         obstack_init(&env.obst);
2272         env.changes = 0;
2273
2274         /* init the links, then collect Loads/Stores/Proj's in lists */
2275         master_visited = 0;
2276         irg_walk_graph(irg, firm_clear_link, collect_nodes, &env);
2277
2278         /* now we have collected enough information, optimize */
2279         irg_walk_graph(irg, NULL, do_load_store_optimize, &env);
2280
2281         env.changes |= optimize_loops(irg);
2282
2283         obstack_free(&env.obst, NULL);
2284
2285         /* Handle graph state */
2286         if (env.changes) {
2287                 set_irg_outs_inconsistent(irg);
2288                 set_irg_entity_usage_state(irg, ir_entity_usage_not_computed);
2289         }
2290
2291         if (env.changes & CF_CHANGED) {
2292                 /* is this really needed: Yes, control flow changed, block might
2293                 have Bad() predecessors. */
2294                 set_irg_doms_inconsistent(irg);
2295         }
2296         return env.changes != 0;
2297 }  /* optimize_load_store */
2298
2299 ir_graph_pass_t *optimize_load_store_pass(const char *name)
2300 {
2301         return def_graph_pass_ret(name ? name : "ldst", optimize_load_store);
2302 }  /* optimize_load_store_pass */