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         if (is_Proj(ptr)) {
 727                 if (get_irn_n_edges(ptr) <= 0) {
 728                         /* this Proj is dead now */
 729                         ir_node *pred = get_Proj_pred(ptr);
 730
 731                         if (is_Load(pred)) {
 732                                 ldst_info_t *info = get_irn_link(pred);
 733                                 info->projs[get_Proj_proj(ptr)] = NULL;
 734
 735                                 /* this node lost its result proj, handle that */
 736                                 handle_load_update(pred);
 737                         }
 738                 }
 739         }
 740 }  /* reduce_adr_usage */
 741
 742 /**
 743  * Check, if an already existing value of mode old_mode can be converted
 744  * into the needed one new_mode without loss.
 745  */
 746 static int can_use_stored_value(ir_mode *old_mode, ir_mode *new_mode)
 747 {
 748         if (old_mode == new_mode)
 749                 return 1;
 750
 751         /* if both modes are two-complement ones, we can always convert the
 752            Stored value into the needed one. */
 753         if (get_mode_size_bits(old_mode) >= get_mode_size_bits(new_mode) &&
 754                   get_mode_arithmetic(old_mode) == irma_twos_complement &&
 755                   get_mode_arithmetic(new_mode) == irma_twos_complement)
 756                 return 1;
 757         return 0;
 758 }  /* can_use_stored_value */
 759
 760 /**
 761  * Check whether a Call is at least pure, ie. does only read memory.
 762  */
 763 static unsigned is_Call_pure(ir_node *call)
 764 {
 765         ir_type *call_tp = get_Call_type(call);
 766         unsigned prop = get_method_additional_properties(call_tp);
 767
 768         /* check first the call type */
 769         if ((prop & (mtp_property_const|mtp_property_pure)) == 0) {
 770                 /* try the called entity */
 771                 ir_node *ptr = get_Call_ptr(call);
 772
 773                 if (is_Global(ptr)) {
 774                         ir_entity *ent = get_Global_entity(ptr);
 775
 776                         prop = get_entity_additional_properties(ent);
 777                 }
 778         }
 779         return (prop & (mtp_property_const|mtp_property_pure)) != 0;
 780 }  /* is_Call_pure */
 781
 782 static ir_node *get_base_and_offset(ir_node *ptr, long *pOffset)
 783 {
 784         ir_mode *mode  = get_irn_mode(ptr);
 785         long    offset = 0;
 786
 787         /* TODO: long might not be enough, we should probably use some tarval thingy... */
 788         for (;;) {
 789                 if (is_Add(ptr)) {
 790                         ir_node *l = get_Add_left(ptr);
 791                         ir_node *r = get_Add_right(ptr);
 792
 793                         if (get_irn_mode(l) != mode || !is_Const(r))
 794                                 break;
 795
 796                         offset += get_tarval_long(get_Const_tarval(r));
 797                         ptr     = l;
 798                 } else if (is_Sub(ptr)) {
 799                         ir_node *l = get_Sub_left(ptr);
 800                         ir_node *r = get_Sub_right(ptr);
 801
 802                         if (get_irn_mode(l) != mode || !is_Const(r))
 803                                 break;
 804
 805                         offset -= get_tarval_long(get_Const_tarval(r));
 806                         ptr     = l;
 807                 } else if (is_Sel(ptr)) {
 808                         ir_entity *ent = get_Sel_entity(ptr);
 809                         ir_type   *tp  = get_entity_owner(ent);
 810
 811                         if (is_Array_type(tp)) {
 812                                 int     size;
 813                                 ir_node *index;
 814
 815                                 /* only one dimensional arrays yet */
 816                                 if (get_Sel_n_indexs(ptr) != 1)
 817                                         break;
 818                                 index = get_Sel_index(ptr, 0);
 819                                 if (! is_Const(index))
 820                                         break;
 821
 822                                 tp = get_entity_type(ent);
 823                                 if (get_type_state(tp) != layout_fixed)
 824                                         break;
 825
 826                                 size    = get_type_size_bytes(tp);
 827                                 offset += size * get_tarval_long(get_Const_tarval(index));
 828                         } else {
 829                                 if (get_type_state(tp) != layout_fixed)
 830                                         break;
 831                                 offset += get_entity_offset(ent);
 832                         }
 833                         ptr = get_Sel_ptr(ptr);
 834                 } else
 835                         break;
 836         }
 837
 838         *pOffset = offset;
 839         return ptr;
 840 }
 841
 842 static int try_load_after_store(ir_node *load,
 843                 ir_node *load_base_ptr, long load_offset, ir_node *store)
 844 {
 845         ldst_info_t *info;
 846         ir_node *store_ptr      = get_Store_ptr(store);
 847         long     store_offset;
 848         ir_node *store_base_ptr = get_base_and_offset(store_ptr, &store_offset);
 849         ir_node *store_value;
 850         ir_mode *store_mode;
 851         ir_node *load_ptr;
 852         ir_mode *load_mode;
 853         long     load_mode_len;
 854         long     store_mode_len;
 855         long     delta;
 856         int      res;
 857
 858         if (load_base_ptr != store_base_ptr)
 859                 return 0;
 860
 861         load_mode      = get_Load_mode(load);
 862         load_mode_len  = get_mode_size_bytes(load_mode);
 863         store_mode     = get_irn_mode(get_Store_value(store));
 864         store_mode_len = get_mode_size_bytes(store_mode);
 865         delta          = load_offset - store_offset;
 866         store_value    = get_Store_value(store);
 867
 868         if (delta != 0 || store_mode != load_mode) {
 869                 if (delta < 0 || delta + load_mode_len > store_mode_len)
 870                         return 0;
 871
 872                 if (get_mode_arithmetic(store_mode) != irma_twos_complement ||
 873                         get_mode_arithmetic(load_mode)  != irma_twos_complement)
 874                         return 0;
 875
 876
 877                 /* produce a shift to adjust offset delta */
 878                 if (delta > 0) {
 879                         ir_node *cnst;
 880
 881                         /* FIXME: only true for little endian */
 882                         cnst        = new_Const_long(mode_Iu, delta * 8);
 883                         store_value = new_r_Shr(get_nodes_block(load),
 884                                                                         store_value, cnst, store_mode);
 885                 }
 886
 887                 /* add an convert if needed */
 888                 if (store_mode != load_mode) {
 889                         store_value = new_r_Conv(get_nodes_block(load), store_value, load_mode);
 890                 }
 891         }
 892
 893         DBG_OPT_RAW(load, store_value);
 894
 895         info = get_irn_link(load);
 896         if (info->projs[pn_Load_M])
 897                 exchange(info->projs[pn_Load_M], get_Load_mem(load));
 898
 899         res = 0;
 900         /* no exception */
 901         if (info->projs[pn_Load_X_except]) {
 902                 exchange( info->projs[pn_Load_X_except], new_Bad());
 903                 res |= CF_CHANGED;
 904         }
 905         if (info->projs[pn_Load_X_regular]) {
 906                 exchange( info->projs[pn_Load_X_regular], new_r_Jmp(get_nodes_block(load)));
 907                 res |= CF_CHANGED;
 908         }
 909
 910         if (info->projs[pn_Load_res])
 911                 exchange(info->projs[pn_Load_res], store_value);
 912
 913         load_ptr = get_Load_ptr(load);
 914         kill_node(load);
 915         reduce_adr_usage(load_ptr);
 916         return res | DF_CHANGED;
 917 }
 918
 919 /**
 920  * Follow the memory chain as long as there are only Loads,
 921  * alias free Stores, and constant Calls and try to replace the
 922  * current Load by a previous ones.
 923  * Note that in unreachable loops it might happen that we reach
 924  * load again, as well as we can fall into a cycle.
 925  * We break such cycles using a special visited flag.
 926  *
 927  * INC_MASTER() must be called before dive into
 928  */
 929 static unsigned follow_Mem_chain(ir_node *load, ir_node *curr)
 930 {
 931         unsigned    res = 0;
 932         ldst_info_t *info = get_irn_link(load);
 933         ir_node     *pred;
 934         ir_node     *ptr       = get_Load_ptr(load);
 935         ir_node     *mem       = get_Load_mem(load);
 936         ir_mode     *load_mode = get_Load_mode(load);
 937
 938         for (pred = curr; load != pred; ) {
 939                 ldst_info_t *pred_info = get_irn_link(pred);
 940
 941                 /*
 942                  * a Load immediately after a Store -- a read after write.
 943                  * We may remove the Load, if both Load & Store does not have an
 944                  * exception handler OR they are in the same MacroBlock. In the latter
 945                  * case the Load cannot throw an exception when the previous Store was
 946                  * quiet.
 947                  *
 948                  * Why we need to check for Store Exception? If the Store cannot
 949                  * be executed (ROM) the exception handler might simply jump into
 950                  * the load MacroBlock :-(
 951                  * We could make it a little bit better if we would know that the
 952                  * exception handler of the Store jumps directly to the end...
 953                  */
 954                 if (is_Store(pred) && ((pred_info->projs[pn_Store_X_except] == NULL
 955                                 && info->projs[pn_Load_X_except] == NULL)
 956                                 || get_nodes_MacroBlock(load) == get_nodes_MacroBlock(pred)))
 957                 {
 958                         long    load_offset;
 959                         ir_node *base_ptr = get_base_and_offset(ptr, &load_offset);
 960                         int     changes   = try_load_after_store(load, base_ptr, load_offset, pred);
 961
 962                         if (changes != 0)
 963                                 return res | changes;
 964                 } else if (is_Load(pred) && get_Load_ptr(pred) == ptr &&
 965                            can_use_stored_value(get_Load_mode(pred), load_mode)) {
 966                         /*
 967                          * a Load after a Load -- a read after read.
 968                          * We may remove the second Load, if it does not have an exception handler
 969                          * OR they are in the same MacroBlock. In the later case the Load cannot
 970                          * throw an exception when the previous Load was quiet.
 971                          *
 972                          * Here, there is no need to check if the previous Load has an exception
 973                          * hander because they would have exact the same exception...
 974                          */
 975                         if (info->projs[pn_Load_X_except] == NULL || get_nodes_MacroBlock(load) == get_nodes_MacroBlock(pred)) {
 976                                 ir_node *value;
 977
 978                                 DBG_OPT_RAR(load, pred);
 979
 980                                 /* the result is used */
 981                                 if (info->projs[pn_Load_res]) {
 982                                         if (pred_info->projs[pn_Load_res] == NULL) {
 983                                                 /* create a new Proj again */
 984                                                 pred_info->projs[pn_Load_res] = new_r_Proj(get_nodes_block(pred), pred, get_Load_mode(pred), pn_Load_res);
 985                                         }
 986                                         value = pred_info->projs[pn_Load_res];
 987
 988                                         /* add an convert if needed */
 989                                         if (get_Load_mode(pred) != load_mode) {
 990                                                 value = new_r_Conv(get_nodes_block(load), value, load_mode);
 991                                         }
 992
 993                                         exchange(info->projs[pn_Load_res], value);
 994                                 }
 995
 996                                 if (info->projs[pn_Load_M])
 997                                         exchange(info->projs[pn_Load_M], mem);
 998
 999                                 /* no exception */
1000                                 if (info->projs[pn_Load_X_except]) {
1001                                         exchange(info->projs[pn_Load_X_except], new_Bad());
1002                                         res |= CF_CHANGED;
1003                                 }
1004                                 if (info->projs[pn_Load_X_regular]) {
1005                                         exchange( info->projs[pn_Load_X_regular], new_r_Jmp(get_nodes_block(load)));
1006                                         res |= CF_CHANGED;
1007                                 }
1008
1009                                 kill_node(load);
1010                                 reduce_adr_usage(ptr);
1011                                 return res |= DF_CHANGED;
1012                         }
1013                 }
1014
1015                 if (is_Store(pred)) {
1016                         /* check if we can pass through this store */
1017                         ir_alias_relation rel = get_alias_relation(
1018                                 current_ir_graph,
1019                                 get_Store_ptr(pred),
1020                                 get_irn_mode(get_Store_value(pred)),
1021                                 ptr, load_mode);
1022                         /* if the might be an alias, we cannot pass this Store */
1023                         if (rel != ir_no_alias)
1024                                 break;
1025                         pred = skip_Proj(get_Store_mem(pred));
1026                 } else if (is_Load(pred)) {
1027                         pred = skip_Proj(get_Load_mem(pred));
1028                 } else if (is_Call(pred)) {
1029                         if (is_Call_pure(pred)) {
1030                                 /* The called graph is at least pure, so there are no Store's
1031                                    in it. We can handle it like a Load and skip it. */
1032                                 pred = skip_Proj(get_Call_mem(pred));
1033                         } else {
1034                                 /* there might be Store's in the graph, stop here */
1035                                 break;
1036                         }
1037                 } else {
1038                         /* follow only Load chains */
1039                         break;
1040                 }
1041
1042                 /* check for cycles */
1043                 if (NODE_VISITED(pred_info))
1044                         break;
1045                 MARK_NODE(pred_info);
1046         }
1047
1048         if (is_Sync(pred)) {
1049                 int i;
1050
1051                 /* handle all Sync predecessors */
1052                 for (i = get_Sync_n_preds(pred) - 1; i >= 0; --i) {
1053                         res |= follow_Mem_chain(load, skip_Proj(get_Sync_pred(pred, i)));
1054                         if (res)
1055                                 return res;
1056                 }
1057         }
1058
1059         return res;
1060 }  /* follow_Mem_chain */
1061
1062 /*
1063  * Check if we can replace the load by a given const from
1064  * the const code irg.
1065  */
1066 ir_node *can_replace_load_by_const(const ir_node *load, ir_node *c)
1067 {
1068         ir_mode *c_mode = get_irn_mode(c);
1069         ir_mode *l_mode = get_Load_mode(load);
1070         ir_node *res    = NULL;
1071
1072         if (c_mode != l_mode) {
1073                 /* check, if the mode matches OR can be easily converted info */
1074                 if (is_reinterpret_cast(c_mode, l_mode)) {
1075                         /* we can safely cast */
1076                         dbg_info *dbg   = get_irn_dbg_info(load);
1077                         ir_node  *block = get_nodes_block(load);
1078
1079                         /* copy the value from the const code irg and cast it */
1080                         res = copy_const_value(dbg, c);
1081                         res = new_rd_Conv(dbg, block, res, l_mode);
1082                 }
1083         } else {
1084                 /* copy the value from the const code irg */
1085                 res = copy_const_value(get_irn_dbg_info(load), c);
1086         }
1087         return res;
1088 }  /* can_replace_load_by_const */
1089
1090 /**
1091  * optimize a Load
1092  *
1093  * @param load  the Load node
1094  */
1095 static unsigned optimize_load(ir_node *load)
1096 {
1097         ldst_info_t *info = get_irn_link(load);
1098         ir_node     *mem, *ptr, *value;
1099         ir_entity   *ent;
1100         long        dummy;
1101         unsigned    res = 0;
1102
1103         /* do NOT touch volatile loads for now */
1104         if (get_Load_volatility(load) == volatility_is_volatile)
1105                 return 0;
1106
1107         /* the address of the load to be optimized */
1108         ptr = get_Load_ptr(load);
1109
1110         /*
1111          * Check if we can remove the exception from a Load:
1112          * This can be done, if the address is from an Sel(Alloc) and
1113          * the Sel type is a subtype of the allocated type.
1114          *
1115          * This optimizes some often used OO constructs,
1116          * like x = new O; x->t;
1117          */
1118         if (info->projs[pn_Load_X_except]) {
1119                 ir_node *addr = ptr;
1120
1121                 /* find base address */
1122                 while (is_Sel(addr))
1123                         addr = get_Sel_ptr(addr);
1124                 if (is_Alloc(skip_Proj(skip_Cast(addr)))) {
1125                         /* simple case: a direct load after an Alloc. Firm Alloc throw
1126                          * an exception in case of out-of-memory. So, there is no way for an
1127                          * exception in this load.
1128                          * This code is constructed by the "exception lowering" in the Jack compiler.
1129                          */
1130                         exchange(info->projs[pn_Load_X_except], new_Bad());
1131                         info->projs[pn_Load_X_except] = NULL;
1132                         exchange(info->projs[pn_Load_X_regular], new_r_Jmp(get_nodes_block(load)));
1133                         info->projs[pn_Load_X_regular] = NULL;
1134                         res |= CF_CHANGED;
1135                 }
1136         }
1137
1138         /* The mem of the Load. Must still be returned after optimization. */
1139         mem = get_Load_mem(load);
1140
1141         if (! info->projs[pn_Load_res] && ! info->projs[pn_Load_X_except]) {
1142                 /* a Load which value is neither used nor exception checked, remove it */
1143                 exchange(info->projs[pn_Load_M], mem);
1144
1145                 if (info->projs[pn_Load_X_regular]) {
1146                         /* should not happen, but if it does, remove it */
1147                         exchange(info->projs[pn_Load_X_regular], new_r_Jmp(get_nodes_block(load)));
1148                         res |= CF_CHANGED;
1149                 }
1150                 kill_node(load);
1151                 reduce_adr_usage(ptr);
1152                 return res | DF_CHANGED;
1153         }
1154
1155         /* Load from a constant polymorphic field, where we can resolve
1156            polymorphism. */
1157         value = transform_polymorph_Load(load);
1158         if (value == load) {
1159                 value = NULL;
1160                 /* check if we can determine the entity that will be loaded */
1161                 ent = find_constant_entity(ptr);
1162                 if (ent != NULL
1163                                 && get_entity_visibility(ent) != ir_visibility_external) {
1164                         /* a static allocation that is not external: there should be NO
1165                          * exception when loading even if we cannot replace the load itself.
1166                          */
1167
1168                         /* no exception, clear the info field as it might be checked later again */
1169                         if (info->projs[pn_Load_X_except]) {
1170                                 exchange(info->projs[pn_Load_X_except], new_Bad());
1171                                 info->projs[pn_Load_X_except] = NULL;
1172                                 res |= CF_CHANGED;
1173                         }
1174                         if (info->projs[pn_Load_X_regular]) {
1175                                 exchange(info->projs[pn_Load_X_regular], new_r_Jmp(get_nodes_block(load)));
1176                                 info->projs[pn_Load_X_regular] = NULL;
1177                                 res |= CF_CHANGED;
1178                         }
1179
1180                         if (get_entity_linkage(ent) & IR_LINKAGE_CONSTANT) {
1181                                 if (ent->initializer != NULL) {
1182                                         /* new style initializer */
1183                                         value = find_compound_ent_value(ptr);
1184                                 } else if (entity_has_compound_ent_values(ent)) {
1185                                         /* old style initializer */
1186                                         compound_graph_path *path = get_accessed_path(ptr);
1187
1188                                         if (path != NULL) {
1189                                                 assert(is_proper_compound_graph_path(path, get_compound_graph_path_length(path)-1));
1190
1191                                                 value = get_compound_ent_value_by_path(ent, path);
1192                                                 DB((dbg, LEVEL_1, "  Constant access at %F%F resulted in %+F\n", ent, path, value));
1193                                                 free_compound_graph_path(path);
1194                                         }
1195                                 }
1196                                 if (value != NULL)
1197                                         value = can_replace_load_by_const(load, value);
1198                         }
1199                 }
1200         }
1201         if (value != NULL) {
1202                 /* we completely replace the load by this value */
1203                 if (info->projs[pn_Load_X_except]) {
1204                         exchange(info->projs[pn_Load_X_except], new_Bad());
1205                         info->projs[pn_Load_X_except] = NULL;
1206                         res |= CF_CHANGED;
1207                 }
1208                 if (info->projs[pn_Load_X_regular]) {
1209                         exchange(info->projs[pn_Load_X_regular], new_r_Jmp(get_nodes_block(load)));
1210                         info->projs[pn_Load_X_regular] = NULL;
1211                         res |= CF_CHANGED;
1212                 }
1213                 if (info->projs[pn_Load_M]) {
1214                         exchange(info->projs[pn_Load_M], mem);
1215                         res |= DF_CHANGED;
1216                 }
1217                 if (info->projs[pn_Load_res]) {
1218                         exchange(info->projs[pn_Load_res], value);
1219                         res |= DF_CHANGED;
1220                 }
1221                 kill_node(load);
1222                 reduce_adr_usage(ptr);
1223                 return res;
1224         }
1225
1226         /* Check, if the address of this load is used more than once.
1227          * If not, more load cannot be removed in any case. */
1228         if (get_irn_n_uses(ptr) <= 1 && get_irn_n_uses(get_base_and_offset(ptr, &dummy)) <= 1)
1229                 return res;
1230
1231         /*
1232          * follow the memory chain as long as there are only Loads
1233          * and try to replace current Load or Store by a previous one.
1234          * Note that in unreachable loops it might happen that we reach
1235          * load again, as well as we can fall into a cycle.
1236          * We break such cycles using a special visited flag.
1237          */
1238         INC_MASTER();
1239         res = follow_Mem_chain(load, skip_Proj(mem));
1240         return res;
1241 }  /* optimize_load */
1242
1243 /**
1244  * Check whether a value of mode new_mode would completely overwrite a value
1245  * of mode old_mode in memory.
1246  */
1247 static int is_completely_overwritten(ir_mode *old_mode, ir_mode *new_mode)
1248 {
1249         return get_mode_size_bits(new_mode) >= get_mode_size_bits(old_mode);
1250 }  /* is_completely_overwritten */
1251
1252 /**
1253  * Check whether small is a part of large (starting at same address).
1254  */
1255 static int is_partially_same(ir_node *small, ir_node *large)
1256 {
1257         ir_mode *sm = get_irn_mode(small);
1258         ir_mode *lm = get_irn_mode(large);
1259
1260         /* FIXME: Check endianness */
1261         return is_Conv(small) && get_Conv_op(small) == large
1262             && get_mode_size_bytes(sm) < get_mode_size_bytes(lm)
1263             && get_mode_arithmetic(sm) == irma_twos_complement
1264             && get_mode_arithmetic(lm) == irma_twos_complement;
1265 }  /* is_partially_same */
1266
1267 /**
1268  * follow the memory chain as long as there are only Loads and alias free Stores.
1269  *
1270  * INC_MASTER() must be called before dive into
1271  */
1272 static unsigned follow_Mem_chain_for_Store(ir_node *store, ir_node *curr)
1273 {
1274         unsigned res = 0;
1275         ldst_info_t *info = get_irn_link(store);
1276         ir_node *pred;
1277         ir_node *ptr = get_Store_ptr(store);
1278         ir_node *mem = get_Store_mem(store);
1279         ir_node *value = get_Store_value(store);
1280         ir_mode *mode  = get_irn_mode(value);
1281         ir_node *block = get_nodes_block(store);
1282         ir_node *mblk  = get_Block_MacroBlock(block);
1283
1284         for (pred = curr; pred != store;) {
1285                 ldst_info_t *pred_info = get_irn_link(pred);
1286
1287                 /*
1288                  * BEWARE: one might think that checking the modes is useless, because
1289                  * if the pointers are identical, they refer to the same object.
1290                  * This is only true in strong typed languages, not is C were the following
1291                  * is possible *(ir_type1 *)p = a; *(ir_type2 *)p = b ...
1292                  * However, if the size of the mode that is written is bigger or equal the
1293                  * size of the old one, the old value is completely overwritten and can be
1294                  * killed ...
1295                  */
1296                 if (is_Store(pred) && get_Store_ptr(pred) == ptr &&
1297             get_nodes_MacroBlock(pred) == mblk) {
1298                         /*
1299                          * a Store after a Store in the same MacroBlock -- a write after write.
1300                          */
1301
1302                         /*
1303                          * We may remove the first Store, if the old value is completely
1304                          * overwritten or the old value is a part of the new value,
1305                          * and if it does not have an exception handler.
1306                          *
1307                          * TODO: What, if both have the same exception handler ???
1308                          */
1309                         if (get_Store_volatility(pred) != volatility_is_volatile
1310                                 && !pred_info->projs[pn_Store_X_except]) {
1311                                 ir_node *predvalue = get_Store_value(pred);
1312                                 ir_mode *predmode  = get_irn_mode(predvalue);
1313
1314                                 if(is_completely_overwritten(predmode, mode)
1315                                         || is_partially_same(predvalue, value)) {
1316                                         DBG_OPT_WAW(pred, store);
1317                                         exchange(pred_info->projs[pn_Store_M], get_Store_mem(pred));
1318                                         kill_node(pred);
1319                                         reduce_adr_usage(ptr);
1320                                         return DF_CHANGED;
1321                                 }
1322                         }
1323
1324                         /*
1325                          * We may remove the Store, if the old value already contains
1326                          * the new value, and if it does not have an exception handler.
1327                          *
1328                          * TODO: What, if both have the same exception handler ???
1329                          */
1330                         if (get_Store_volatility(store) != volatility_is_volatile
1331                                 && !info->projs[pn_Store_X_except]) {
1332                                 ir_node *predvalue = get_Store_value(pred);
1333
1334                                 if(is_partially_same(value, predvalue)) {
1335                                         DBG_OPT_WAW(pred, store);
1336                                         exchange(info->projs[pn_Store_M], mem);
1337                                         kill_node(store);
1338                                         reduce_adr_usage(ptr);
1339                                         return DF_CHANGED;
1340                                 }
1341                         }
1342                 } else if (is_Load(pred) && get_Load_ptr(pred) == ptr &&
1343                            value == pred_info->projs[pn_Load_res]) {
1344                         /*
1345                          * a Store of a value just loaded from the same address
1346                          * -- a write after read.
1347                          * We may remove the Store, if it does not have an exception
1348                          * handler.
1349                          */
1350                         if (! info->projs[pn_Store_X_except]) {
1351                                 DBG_OPT_WAR(store, pred);
1352                                 exchange(info->projs[pn_Store_M], mem);
1353                                 kill_node(store);
1354                                 reduce_adr_usage(ptr);
1355                                 return DF_CHANGED;
1356                         }
1357                 }
1358
1359                 if (is_Store(pred)) {
1360                         /* check if we can pass through this store */
1361                         ir_alias_relation rel = get_alias_relation(
1362                                 current_ir_graph,
1363                                 get_Store_ptr(pred),
1364                                 get_irn_mode(get_Store_value(pred)),
1365                                 ptr, mode);
1366                         /* if the might be an alias, we cannot pass this Store */
1367                         if (rel != ir_no_alias)
1368                                 break;
1369                         pred = skip_Proj(get_Store_mem(pred));
1370                 } else if (is_Load(pred)) {
1371                         ir_alias_relation rel = get_alias_relation(
1372                                 current_ir_graph, get_Load_ptr(pred), get_Load_mode(pred),
1373                                 ptr, mode);
1374                         if (rel != ir_no_alias)
1375                                 break;
1376
1377                         pred = skip_Proj(get_Load_mem(pred));
1378                 } else {
1379                         /* follow only Load chains */
1380                         break;
1381                 }
1382
1383                 /* check for cycles */
1384                 if (NODE_VISITED(pred_info))
1385                         break;
1386                 MARK_NODE(pred_info);
1387         }
1388
1389         if (is_Sync(pred)) {
1390                 int i;
1391
1392                 /* handle all Sync predecessors */
1393                 for (i = get_Sync_n_preds(pred) - 1; i >= 0; --i) {
1394                         res |= follow_Mem_chain_for_Store(store, skip_Proj(get_Sync_pred(pred, i)));
1395                         if (res)
1396                                 break;
1397                 }
1398         }
1399         return res;
1400 }  /* follow_Mem_chain_for_Store */
1401
1402 /** find entity used as base for an address calculation */
1403 static ir_entity *find_entity(ir_node *ptr)
1404 {
1405         switch(get_irn_opcode(ptr)) {
1406         case iro_SymConst:
1407                 return get_SymConst_entity(ptr);
1408         case iro_Sel: {
1409                 ir_node *pred = get_Sel_ptr(ptr);
1410                 if (get_irg_frame(get_irn_irg(ptr)) == pred)
1411                         return get_Sel_entity(ptr);
1412
1413                 return find_entity(pred);
1414         }
1415         case iro_Sub:
1416         case iro_Add: {
1417                 ir_node *left = get_binop_left(ptr);
1418                 ir_node *right;
1419                 if (mode_is_reference(get_irn_mode(left)))
1420                         return find_entity(left);
1421                 right = get_binop_right(ptr);
1422                 if (mode_is_reference(get_irn_mode(right)))
1423                         return find_entity(right);
1424                 return NULL;
1425         }
1426         default:
1427                 return NULL;
1428         }
1429 }
1430
1431 /**
1432  * optimize a Store
1433  *
1434  * @param store  the Store node
1435  */
1436 static unsigned optimize_store(ir_node *store)
1437 {
1438         ir_node   *ptr;
1439         ir_node   *mem;
1440         ir_entity *entity;
1441
1442         if (get_Store_volatility(store) == volatility_is_volatile)
1443                 return 0;
1444
1445         ptr    = get_Store_ptr(store);
1446         entity = find_entity(ptr);
1447
1448         /* a store to an entity which is never read is unnecessary */
1449         if (entity != NULL && !(get_entity_usage(entity) & ir_usage_read)) {
1450                 ldst_info_t *info = get_irn_link(store);
1451                 if (info->projs[pn_Store_X_except] == NULL) {
1452                         DB((dbg, LEVEL_1, "  Killing useless %+F to never read entity %+F\n", store, entity));
1453                         exchange(info->projs[pn_Store_M], get_Store_mem(store));
1454                         kill_node(store);
1455                         reduce_adr_usage(ptr);
1456                         return DF_CHANGED;
1457                 }
1458         }
1459
1460         /* Check, if the address of this Store is used more than once.
1461          * If not, this Store cannot be removed in any case. */
1462         if (get_irn_n_uses(ptr) <= 1)
1463                 return 0;
1464
1465         mem = get_Store_mem(store);
1466
1467         /* follow the memory chain as long as there are only Loads */
1468         INC_MASTER();
1469
1470         return follow_Mem_chain_for_Store(store, skip_Proj(mem));
1471 }  /* optimize_store */
1472
1473 /**
1474  * walker, optimizes Phi after Stores to identical places:
1475  * Does the following optimization:
1476  * @verbatim
1477  *
1478  *   val1   val2   val3          val1  val2  val3
1479  *    |      |      |               \    |    /
1480  *  Store  Store  Store              \   |   /
1481  *      \    |    /                   PhiData
1482  *       \   |   /                       |
1483  *        \  |  /                      Store
1484  *          PhiM
1485  *
1486  * @endverbatim
1487  * This reduces the number of stores and allows for predicated execution.
1488  * Moves Stores back to the end of a function which may be bad.
1489  *
1490  * This is only possible if the predecessor blocks have only one successor.
1491  */
1492 static unsigned optimize_phi(ir_node *phi, walk_env_t *wenv)
1493 {
1494         int i, n;
1495         ir_node *store, *old_store, *ptr, *block, *phi_block, *phiM, *phiD, *exc, *projM;
1496         ir_mode *mode;
1497         ir_node **inM, **inD, **projMs;
1498         int *idx;
1499         dbg_info *db = NULL;
1500         ldst_info_t *info;
1501         block_info_t *bl_info;
1502         unsigned res = 0;
1503
1504         /* Must be a memory Phi */
1505         if (get_irn_mode(phi) != mode_M)
1506                 return 0;
1507
1508         n = get_Phi_n_preds(phi);
1509         if (n <= 0)
1510                 return 0;
1511
1512         /* must be only one user */
1513         projM = get_Phi_pred(phi, 0);
1514         if (get_irn_n_edges(projM) != 1)
1515                 return 0;
1516
1517         store = skip_Proj(projM);
1518         old_store = store;
1519         if (!is_Store(store))
1520                 return 0;
1521
1522         block = get_nodes_block(store);
1523
1524         /* abort on dead blocks */
1525         if (is_Block_dead(block))
1526                 return 0;
1527
1528         /* check if the block is post dominated by Phi-block
1529            and has no exception exit */
1530         bl_info = get_irn_link(block);
1531         if (bl_info->flags & BLOCK_HAS_EXC)
1532                 return 0;
1533
1534         phi_block = get_nodes_block(phi);
1535         if (! block_strictly_postdominates(phi_block, block))
1536                 return 0;
1537
1538         /* this is the address of the store */
1539         ptr  = get_Store_ptr(store);
1540         mode = get_irn_mode(get_Store_value(store));
1541         info = get_irn_link(store);
1542         exc  = info->exc_block;
1543
1544         for (i = 1; i < n; ++i) {
1545                 ir_node *pred = get_Phi_pred(phi, i);
1546
1547                 if (get_irn_n_edges(pred) != 1)
1548                         return 0;
1549
1550                 pred = skip_Proj(pred);
1551                 if (!is_Store(pred))
1552                         return 0;
1553
1554                 if (ptr != get_Store_ptr(pred) || mode != get_irn_mode(get_Store_value(pred)))
1555                         return 0;
1556
1557                 info = get_irn_link(pred);
1558
1559                 /* check, if all stores have the same exception flow */
1560                 if (exc != info->exc_block)
1561                         return 0;
1562
1563                 /* abort on dead blocks */
1564                 block = get_nodes_block(pred);
1565                 if (is_Block_dead(block))
1566                         return 0;
1567
1568                 /* check if the block is post dominated by Phi-block
1569                    and has no exception exit. Note that block must be different from
1570                    Phi-block, else we would move a Store from end End of a block to its
1571                    Start... */
1572                 bl_info = get_irn_link(block);
1573                 if (bl_info->flags & BLOCK_HAS_EXC)
1574                         return 0;
1575                 if (block == phi_block || ! block_postdominates(phi_block, block))
1576                         return 0;
1577         }
1578
1579         /*
1580          * ok, when we are here, we found all predecessors of a Phi that
1581          * are Stores to the same address and size. That means whatever
1582          * we do before we enter the block of the Phi, we do a Store.
1583          * So, we can move the Store to the current block:
1584          *
1585          *   val1    val2    val3          val1  val2  val3
1586          *    |       |       |               \    |    /
1587          * | Str | | Str | | Str |             \   |   /
1588          *      \     |     /                   PhiData
1589          *       \    |    /                       |
1590          *        \   |   /                       Str
1591          *           PhiM
1592          *
1593          * Is only allowed if the predecessor blocks have only one successor.
1594          */
1595
1596         NEW_ARR_A(ir_node *, projMs, n);
1597         NEW_ARR_A(ir_node *, inM, n);
1598         NEW_ARR_A(ir_node *, inD, n);
1599         NEW_ARR_A(int, idx, n);
1600
1601         /* Prepare: Collect all Store nodes.  We must do this
1602            first because we otherwise may loose a store when exchanging its
1603            memory Proj.
1604          */
1605         for (i = n - 1; i >= 0; --i) {
1606                 ir_node *store;
1607
1608                 projMs[i] = get_Phi_pred(phi, i);
1609                 assert(is_Proj(projMs[i]));
1610
1611                 store = get_Proj_pred(projMs[i]);
1612                 info  = get_irn_link(store);
1613
1614                 inM[i] = get_Store_mem(store);
1615                 inD[i] = get_Store_value(store);
1616                 idx[i] = info->exc_idx;
1617         }
1618         block = get_nodes_block(phi);
1619
1620         /* second step: create a new memory Phi */
1621         phiM = new_rd_Phi(get_irn_dbg_info(phi), block, n, inM, mode_M);
1622
1623         /* third step: create a new data Phi */
1624         phiD = new_rd_Phi(get_irn_dbg_info(phi), block, n, inD, mode);
1625
1626         /* rewire memory and kill the node */
1627         for (i = n - 1; i >= 0; --i) {
1628                 ir_node *proj  = projMs[i];
1629
1630                 if(is_Proj(proj)) {
1631                         ir_node *store = get_Proj_pred(proj);
1632                         exchange(proj, inM[i]);
1633                         kill_node(store);
1634                 }
1635         }
1636
1637         /* fourth step: create the Store */
1638         store = new_rd_Store(db, block, phiM, ptr, phiD, 0);
1639 #ifdef DO_CACHEOPT
1640         co_set_irn_name(store, co_get_irn_ident(old_store));
1641 #endif
1642
1643         projM = new_rd_Proj(NULL, block, store, mode_M, pn_Store_M);
1644
1645         info = get_ldst_info(store, &wenv->obst);
1646         info->projs[pn_Store_M] = projM;
1647
1648         /* fifths step: repair exception flow */
1649         if (exc) {
1650                 ir_node *projX = new_rd_Proj(NULL, block, store, mode_X, pn_Store_X_except);
1651
1652                 info->projs[pn_Store_X_except] = projX;
1653                 info->exc_block                = exc;
1654                 info->exc_idx                  = idx[0];
1655
1656                 for (i = 0; i < n; ++i) {
1657                         set_Block_cfgpred(exc, idx[i], projX);
1658                 }
1659
1660                 if (n > 1) {
1661                         /* the exception block should be optimized as some inputs are identical now */
1662                 }
1663
1664                 res |= CF_CHANGED;
1665         }
1666
1667         /* sixth step: replace old Phi */
1668         exchange(phi, projM);
1669
1670         return res | DF_CHANGED;
1671 }  /* optimize_phi */
1672
1673 /**
1674  * walker, do the optimizations
1675  */
1676 static void do_load_store_optimize(ir_node *n, void *env)
1677 {
1678         walk_env_t *wenv = env;
1679
1680         switch (get_irn_opcode(n)) {
1681
1682         case iro_Load:
1683                 wenv->changes |= optimize_load(n);
1684                 break;
1685
1686         case iro_Store:
1687                 wenv->changes |= optimize_store(n);
1688                 break;
1689
1690         case iro_Phi:
1691                 wenv->changes |= optimize_phi(n, wenv);
1692                 break;
1693
1694         default:
1695                 ;
1696         }
1697 }  /* do_load_store_optimize */
1698
1699 /** A scc. */
1700 typedef struct scc {
1701         ir_node *head;          /**< the head of the list */
1702 } scc;
1703
1704 /** A node entry. */
1705 typedef struct node_entry {
1706         unsigned DFSnum;    /**< the DFS number of this node */
1707         unsigned low;       /**< the low number of this node */
1708         int      in_stack;  /**< flag, set if the node is on the stack */
1709         ir_node  *next;     /**< link to the next node the the same scc */
1710         scc      *pscc;     /**< the scc of this node */
1711         unsigned POnum;     /**< the post order number for blocks */
1712 } node_entry;
1713
1714 /** A loop entry. */
1715 typedef struct loop_env {
1716         ir_phase ph;           /**< the phase object */
1717         ir_node  **stack;      /**< the node stack */
1718         int      tos;          /**< tos index */
1719         unsigned nextDFSnum;   /**< the current DFS number */
1720         unsigned POnum;        /**< current post order number */
1721
1722         unsigned changes;      /**< a bitmask of graph changes */
1723 } loop_env;
1724
1725 /**
1726 * Gets the node_entry of a node
1727 */
1728 static node_entry *get_irn_ne(ir_node *irn, loop_env *env)
1729 {
1730         ir_phase   *ph = &env->ph;
1731         node_entry *e  = phase_get_irn_data(&env->ph, irn);
1732
1733         if (! e) {
1734                 e = phase_alloc(ph, sizeof(*e));
1735                 memset(e, 0, sizeof(*e));
1736                 phase_set_irn_data(ph, irn, e);
1737         }
1738         return e;
1739 }  /* get_irn_ne */
1740
1741 /**
1742  * Push a node onto the stack.
1743  *
1744  * @param env   the loop environment
1745  * @param n     the node to push
1746  */
1747 static void push(loop_env *env, ir_node *n)
1748 {
1749         node_entry *e;
1750
1751         if (env->tos == ARR_LEN(env->stack)) {
1752                 int nlen = ARR_LEN(env->stack) * 2;
1753                 ARR_RESIZE(ir_node *, env->stack, nlen);
1754         }
1755         env->stack[env->tos++] = n;
1756         e = get_irn_ne(n, env);
1757         e->in_stack = 1;
1758 }  /* push */
1759
1760 /**
1761  * pop a node from the stack
1762  *
1763  * @param env   the loop environment
1764  *
1765  * @return  The topmost node
1766  */
1767 static ir_node *pop(loop_env *env)
1768 {
1769         ir_node *n = env->stack[--env->tos];
1770         node_entry *e = get_irn_ne(n, env);
1771
1772         e->in_stack = 0;
1773         return n;
1774 }  /* pop */
1775
1776 /**
1777  * Check if irn is a region constant.
1778  * The block or irn must strictly dominate the header block.
1779  *
1780  * @param irn           the node to check
1781  * @param header_block  the header block of the induction variable
1782  */
1783 static int is_rc(ir_node *irn, ir_node *header_block)
1784 {
1785         ir_node *block = get_nodes_block(irn);
1786
1787         return (block != header_block) && block_dominates(block, header_block);
1788 }  /* is_rc */
1789
1790 typedef struct phi_entry phi_entry;
1791 struct phi_entry {
1792         ir_node   *phi;    /**< A phi with a region const memory. */
1793         int       pos;     /**< The position of the region const memory */
1794         ir_node   *load;   /**< the newly created load for this phi */
1795         phi_entry *next;
1796 };
1797
1798 /**
1799  * An entry in the avail set.
1800  */
1801 typedef struct avail_entry_t {
1802         ir_node *ptr;   /**< the address pointer */
1803         ir_mode *mode;  /**< the load mode */
1804         ir_node *load;  /**< the associated Load */
1805 } avail_entry_t;
1806
1807 /**
1808  * Compare two avail entries.
1809  */
1810 static int cmp_avail_entry(const void *elt, const void *key, size_t size)
1811 {
1812         const avail_entry_t *a = elt;
1813         const avail_entry_t *b = key;
1814         (void) size;
1815
1816         return a->ptr != b->ptr || a->mode != b->mode;
1817 }  /* cmp_avail_entry */
1818
1819 /**
1820  * Calculate the hash value of an avail entry.
1821  */
1822 static unsigned hash_cache_entry(const avail_entry_t *entry)
1823 {
1824         return get_irn_idx(entry->ptr) * 9 + HASH_PTR(entry->mode);
1825 }  /* hash_cache_entry */
1826
1827 /**
1828  * Move loops out of loops if possible.
1829  *
1830  * @param pscc   the loop described by an SCC
1831  * @param env    the loop environment
1832  */
1833 static void move_loads_out_of_loops(scc *pscc, loop_env *env)
1834 {
1835         ir_node   *phi, *load, *next, *other, *next_other;
1836         ir_entity *ent;
1837         int       j;
1838         phi_entry *phi_list = NULL;
1839         set       *avail;
1840
1841         avail = new_set(cmp_avail_entry, 8);
1842
1843         /* collect all outer memories */
1844         for (phi = pscc->head; phi != NULL; phi = next) {
1845                 node_entry *ne = get_irn_ne(phi, env);
1846                 next = ne->next;
1847
1848                 /* check all memory Phi's */
1849                 if (! is_Phi(phi))
1850                         continue;
1851
1852                 assert(get_irn_mode(phi) == mode_M && "DFS return non-memory Phi");
1853
1854                 for (j = get_irn_arity(phi) - 1; j >= 0; --j) {
1855                         ir_node    *pred = get_irn_n(phi, j);
1856                         node_entry *pe   = get_irn_ne(pred, env);
1857
1858                         if (pe->pscc != ne->pscc) {
1859                                 /* not in the same SCC, is region const */
1860                                 phi_entry *pe = phase_alloc(&env->ph, sizeof(*pe));
1861
1862                                 pe->phi  = phi;
1863                                 pe->pos  = j;
1864                                 pe->next = phi_list;
1865                                 phi_list = pe;
1866                         }
1867                 }
1868         }
1869         /* no Phis no fun */
1870         assert(phi_list != NULL && "DFS found a loop without Phi");
1871
1872         /* for now, we cannot handle more than one input (only reducible cf) */
1873         if (phi_list->next != NULL)
1874                 return;
1875
1876         for (load = pscc->head; load; load = next) {
1877                 ir_mode *load_mode;
1878                 node_entry *ne = get_irn_ne(load, env);
1879                 next = ne->next;
1880
1881                 if (is_Load(load)) {
1882                         ldst_info_t *info = get_irn_link(load);
1883                         ir_node     *ptr = get_Load_ptr(load);
1884
1885                         /* for now, we cannot handle Loads with exceptions */
1886                         if (info->projs[pn_Load_res] == NULL || info->projs[pn_Load_X_regular] != NULL || info->projs[pn_Load_X_except] != NULL)
1887                                 continue;
1888
1889                         /* for now, we can only move Load(Global) */
1890                         if (! is_Global(ptr))
1891                                 continue;
1892                         ent       = get_Global_entity(ptr);
1893                         load_mode = get_Load_mode(load);
1894                         for (other = pscc->head; other != NULL; other = next_other) {
1895                                 node_entry *ne = get_irn_ne(other, env);
1896                                 next_other = ne->next;
1897
1898                                 if (is_Store(other)) {
1899                                         ir_alias_relation rel = get_alias_relation(
1900                                                 current_ir_graph,
1901                                                 get_Store_ptr(other),
1902                                                 get_irn_mode(get_Store_value(other)),
1903                                                 ptr, load_mode);
1904                                         /* if the might be an alias, we cannot pass this Store */
1905                                         if (rel != ir_no_alias)
1906                                                 break;
1907                                 }
1908                                 /* only Phis and pure Calls are allowed here, so ignore them */
1909                         }
1910                         if (other == NULL) {
1911                                 ldst_info_t *ninfo;
1912                                 phi_entry   *pe;
1913                                 dbg_info    *db;
1914
1915                                 /* yep, no aliasing Store found, Load can be moved */
1916                                 DB((dbg, LEVEL_1, "  Found a Load that could be moved: %+F\n", load));
1917
1918                                 db   = get_irn_dbg_info(load);
1919                                 for (pe = phi_list; pe != NULL; pe = pe->next) {
1920                                         int     pos   = pe->pos;
1921                                         ir_node *phi  = pe->phi;
1922                                         ir_node *blk  = get_nodes_block(phi);
1923                                         ir_node *pred = get_Block_cfgpred_block(blk, pos);
1924                                         ir_node *irn, *mem;
1925                                         avail_entry_t entry, *res;
1926
1927                                         entry.ptr  = ptr;
1928                                         entry.mode = load_mode;
1929                                         res = set_find(avail, &entry, sizeof(entry), hash_cache_entry(&entry));
1930                                         if (res != NULL) {
1931                                                 irn = res->load;
1932                                         } else {
1933                                                 irn = new_rd_Load(db, pred, get_Phi_pred(phi, pos), ptr, load_mode, 0);
1934                                                 entry.load = irn;
1935                                                 set_insert(avail, &entry, sizeof(entry), hash_cache_entry(&entry));
1936                                                 DB((dbg, LEVEL_1, "  Created %+F in %+F\n", irn, pred));
1937                                         }
1938                                         pe->load = irn;
1939                                         ninfo = get_ldst_info(irn, phase_obst(&env->ph));
1940
1941                                         ninfo->projs[pn_Load_M] = mem = new_r_Proj(pred, irn, mode_M, pn_Load_M);
1942                                         set_Phi_pred(phi, pos, mem);
1943
1944                                         ninfo->projs[pn_Load_res] = new_r_Proj(pred, irn, load_mode, pn_Load_res);
1945                                 }
1946
1947                                 /* now kill the old Load */
1948                                 exchange(info->projs[pn_Load_M], get_Load_mem(load));
1949                                 exchange(info->projs[pn_Load_res], ninfo->projs[pn_Load_res]);
1950
1951                                 env->changes |= DF_CHANGED;
1952                         }
1953                 }
1954         }
1955         del_set(avail);
1956 }  /* move_loads_out_of_loops */
1957
1958 /**
1959  * Process a loop SCC.
1960  *
1961  * @param pscc  the SCC
1962  * @param env   the loop environment
1963  */
1964 static void process_loop(scc *pscc, loop_env *env)
1965 {
1966         ir_node *irn, *next, *header = NULL;
1967         node_entry *b, *h = NULL;
1968         int j, only_phi, num_outside, process = 0;
1969         ir_node *out_rc;
1970
1971         /* find the header block for this scc */
1972         for (irn = pscc->head; irn; irn = next) {
1973                 node_entry *e = get_irn_ne(irn, env);
1974                 ir_node *block = get_nodes_block(irn);
1975
1976                 next = e->next;
1977                 b = get_irn_ne(block, env);
1978
1979                 if (header != NULL) {
1980                         if (h->POnum < b->POnum) {
1981                                 header = block;
1982                                 h      = b;
1983                         }
1984                 } else {
1985                         header = block;
1986                         h      = b;
1987                 }
1988         }
1989
1990         /* check if this scc contains only Phi, Loads or Stores nodes */
1991         only_phi    = 1;
1992         num_outside = 0;
1993         out_rc      = NULL;
1994         for (irn = pscc->head; irn; irn = next) {
1995                 node_entry *e = get_irn_ne(irn, env);
1996
1997                 next = e->next;
1998                 switch (get_irn_opcode(irn)) {
1999                 case iro_Call:
2000                         if (is_Call_pure(irn)) {
2001                                 /* pure calls can be treated like loads */
2002                                 only_phi = 0;
2003                                 break;
2004                         }
2005                         /* non-pure calls must be handle like may-alias Stores */
2006                         goto fail;
2007                 case iro_CopyB:
2008                         /* cannot handle CopyB yet */
2009                         goto fail;
2010                 case iro_Load:
2011                         process = 1;
2012                         if (get_Load_volatility(irn) == volatility_is_volatile) {
2013                                 /* cannot handle loops with volatile Loads */
2014                                 goto fail;
2015                         }
2016                         only_phi = 0;
2017                         break;
2018                 case iro_Store:
2019                         if (get_Store_volatility(irn) == volatility_is_volatile) {
2020                                 /* cannot handle loops with volatile Stores */
2021                                 goto fail;
2022                         }
2023                         only_phi = 0;
2024                         break;
2025                 default:
2026                         only_phi = 0;
2027                         break;
2028                 case iro_Phi:
2029                         for (j = get_irn_arity(irn) - 1; j >= 0; --j) {
2030                                 ir_node *pred  = get_irn_n(irn, j);
2031                                 node_entry *pe = get_irn_ne(pred, env);
2032
2033                                 if (pe->pscc != e->pscc) {
2034                                         /* not in the same SCC, must be a region const */
2035                                         if (! is_rc(pred, header)) {
2036                                                 /* not a memory loop */
2037                                                 goto fail;
2038                                         }
2039                                         if (out_rc == NULL) {
2040                                                 /* first region constant */
2041                                                 out_rc = pred;
2042                                                 ++num_outside;
2043                                         } else if (out_rc != pred) {
2044                                                 /* another region constant */
2045                                                 ++num_outside;
2046                                         }
2047                                 }
2048                         }
2049                         break;
2050                 }
2051         }
2052         if (! process)
2053                 goto fail;
2054
2055         /* found a memory loop */
2056         DB((dbg, LEVEL_2, "  Found a memory loop:\n  "));
2057         if (only_phi && num_outside == 1) {
2058                 /* a phi cycle with only one real predecessor can be collapsed */
2059                 DB((dbg, LEVEL_2, "  Found an USELESS Phi cycle:\n  "));
2060
2061                 for (irn = pscc->head; irn; irn = next) {
2062                         node_entry *e = get_irn_ne(irn, env);
2063                         next = e->next;
2064                         exchange(irn, out_rc);
2065                 }
2066                 env->changes |= DF_CHANGED;
2067                 return;
2068         }
2069
2070 #ifdef DEBUG_libfirm
2071         for (irn = pscc->head; irn; irn = next) {
2072                 node_entry *e = get_irn_ne(irn, env);
2073                 next = e->next;
2074                 DB((dbg, LEVEL_2, " %+F,", irn));
2075         }
2076         DB((dbg, LEVEL_2, "\n"));
2077 #endif
2078         move_loads_out_of_loops(pscc, env);
2079
2080 fail:
2081         ;
2082 }  /* process_loop */
2083
2084 /**
2085  * Process a SCC.
2086  *
2087  * @param pscc  the SCC
2088  * @param env   the loop environment
2089  */
2090 static void process_scc(scc *pscc, loop_env *env)
2091 {
2092         ir_node *head = pscc->head;
2093         node_entry *e = get_irn_ne(head, env);
2094
2095 #ifdef DEBUG_libfirm
2096         {
2097                 ir_node *irn, *next;
2098
2099                 DB((dbg, LEVEL_4, " SCC at %p:\n ", pscc));
2100                 for (irn = pscc->head; irn; irn = next) {
2101                         node_entry *e = get_irn_ne(irn, env);
2102
2103                         next = e->next;
2104
2105                         DB((dbg, LEVEL_4, " %+F,", irn));
2106                 }
2107                 DB((dbg, LEVEL_4, "\n"));
2108         }
2109 #endif
2110
2111         if (e->next != NULL) {
2112                 /* this SCC has more than one member */
2113                 process_loop(pscc, env);
2114         }
2115 }  /* process_scc */
2116
2117 /**
2118  * Do Tarjan's SCC algorithm and drive load/store optimization.
2119  *
2120  * @param irn  start at this node
2121  * @param env  the loop environment
2122  */
2123 static void dfs(ir_node *irn, loop_env *env)
2124 {
2125         int i, n;
2126         node_entry *node = get_irn_ne(irn, env);
2127
2128         mark_irn_visited(irn);
2129
2130         node->DFSnum = env->nextDFSnum++;
2131         node->low    = node->DFSnum;
2132         push(env, irn);
2133
2134         /* handle preds */
2135         if (is_Phi(irn) || is_Sync(irn)) {
2136                 n = get_irn_arity(irn);
2137                 for (i = 0; i < n; ++i) {
2138                         ir_node *pred = get_irn_n(irn, i);
2139                         node_entry *o = get_irn_ne(pred, env);
2140
2141                         if (!irn_visited(pred)) {
2142                                 dfs(pred, env);
2143                                 node->low = MIN(node->low, o->low);
2144                         }
2145                         if (o->DFSnum < node->DFSnum && o->in_stack)
2146                                 node->low = MIN(o->DFSnum, node->low);
2147                 }
2148         } else if (is_fragile_op(irn)) {
2149                 ir_node *pred = get_fragile_op_mem(irn);
2150                 node_entry *o = get_irn_ne(pred, env);
2151
2152                 if (!irn_visited(pred)) {
2153                         dfs(pred, env);
2154                         node->low = MIN(node->low, o->low);
2155                 }
2156                 if (o->DFSnum < node->DFSnum && o->in_stack)
2157                         node->low = MIN(o->DFSnum, node->low);
2158         } else if (is_Proj(irn)) {
2159                 ir_node *pred = get_Proj_pred(irn);
2160                 node_entry *o = get_irn_ne(pred, env);
2161
2162                 if (!irn_visited(pred)) {
2163                         dfs(pred, env);
2164                         node->low = MIN(node->low, o->low);
2165                 }
2166                 if (o->DFSnum < node->DFSnum && o->in_stack)
2167                         node->low = MIN(o->DFSnum, node->low);
2168         }
2169         else {
2170                  /* IGNORE predecessors */
2171         }
2172
2173         if (node->low == node->DFSnum) {
2174                 scc *pscc = phase_alloc(&env->ph, sizeof(*pscc));
2175                 ir_node *x;
2176
2177                 pscc->head = NULL;
2178                 do {
2179                         node_entry *e;
2180
2181                         x = pop(env);
2182                         e = get_irn_ne(x, env);
2183                         e->pscc    = pscc;
2184                         e->next    = pscc->head;
2185                         pscc->head = x;
2186                 } while (x != irn);
2187
2188                 process_scc(pscc, env);
2189         }
2190 }  /* dfs */
2191
2192 /**
2193  * Do the DFS on the memory edges a graph.
2194  *
2195  * @param irg  the graph to process
2196  * @param env  the loop environment
2197  */
2198 static void do_dfs(ir_graph *irg, loop_env *env)
2199 {
2200         ir_graph *rem = current_ir_graph;
2201         ir_node  *endblk, *end;
2202         int      i;
2203
2204         current_ir_graph = irg;
2205         inc_irg_visited(irg);
2206
2207         /* visit all memory nodes */
2208         endblk = get_irg_end_block(irg);
2209         for (i = get_Block_n_cfgpreds(endblk) - 1; i >= 0; --i) {
2210                 ir_node *pred = get_Block_cfgpred(endblk, i);
2211
2212                 pred = skip_Proj(pred);
2213                 if (is_Return(pred))
2214                         dfs(get_Return_mem(pred), env);
2215                 else if (is_Raise(pred))
2216                         dfs(get_Raise_mem(pred), env);
2217                 else if (is_fragile_op(pred))
2218                         dfs(get_fragile_op_mem(pred), env);
2219                 else {
2220                         assert(0 && "Unknown EndBlock predecessor");
2221                 }
2222         }
2223
2224         /* visit the keep-alives */
2225         end = get_irg_end(irg);
2226         for (i = get_End_n_keepalives(end) - 1; i >= 0; --i) {
2227                 ir_node *ka = get_End_keepalive(end, i);
2228
2229                 if (is_Phi(ka) && !irn_visited(ka))
2230                         dfs(ka, env);
2231         }
2232         current_ir_graph = rem;
2233 }  /* do_dfs */
2234
2235 /**
2236  * Initialize new phase data. We do this always explicit, so return NULL here
2237  */
2238 static void *init_loop_data(ir_phase *ph, const ir_node *irn, void *data)
2239 {
2240         (void)ph;
2241         (void)irn;
2242         (void)data;
2243         return NULL;
2244 }  /* init_loop_data */
2245
2246 /**
2247  * Optimize Loads/Stores in loops.
2248  *
2249  * @param irg  the graph
2250  */
2251 static int optimize_loops(ir_graph *irg)
2252 {
2253         loop_env env;
2254
2255         env.stack         = NEW_ARR_F(ir_node *, 128);
2256         env.tos           = 0;
2257         env.nextDFSnum    = 0;
2258         env.POnum         = 0;
2259         env.changes       = 0;
2260         phase_init(&env.ph, "ldstopt", irg, PHASE_DEFAULT_GROWTH, init_loop_data, NULL);
2261
2262         /* calculate the SCC's and drive loop optimization. */
2263         do_dfs(irg, &env);
2264
2265         DEL_ARR_F(env.stack);
2266         phase_free(&env.ph);
2267
2268         return env.changes;
2269 }  /* optimize_loops */
2270
2271 /*
2272  * do the load store optimization
2273  */
2274 int optimize_load_store(ir_graph *irg)
2275 {
2276         walk_env_t env;
2277
2278         FIRM_DBG_REGISTER(dbg, "firm.opt.ldstopt");
2279
2280         assert(get_irg_phase_state(irg) != phase_building);
2281         assert(get_irg_pinned(irg) != op_pin_state_floats &&
2282                 "LoadStore optimization needs pinned graph");
2283
2284         /* we need landing pads */
2285         remove_critical_cf_edges(irg);
2286
2287         edges_assure(irg);
2288
2289         /* for Phi optimization post-dominators are needed ... */
2290         assure_postdoms(irg);
2291
2292         if (get_opt_alias_analysis()) {
2293                 assure_irg_entity_usage_computed(irg);
2294                 assure_irp_globals_entity_usage_computed();
2295         }
2296
2297         obstack_init(&env.obst);
2298         env.changes = 0;
2299
2300         /* init the links, then collect Loads/Stores/Proj's in lists */
2301         master_visited = 0;
2302         irg_walk_graph(irg, firm_clear_link, collect_nodes, &env);
2303
2304         /* now we have collected enough information, optimize */
2305         irg_walk_graph(irg, NULL, do_load_store_optimize, &env);
2306
2307         env.changes |= optimize_loops(irg);
2308
2309         obstack_free(&env.obst, NULL);
2310
2311         /* Handle graph state */
2312         if (env.changes) {
2313                 set_irg_outs_inconsistent(irg);
2314                 set_irg_entity_usage_state(irg, ir_entity_usage_not_computed);
2315         }
2316
2317         if (env.changes & CF_CHANGED) {
2318                 /* is this really needed: Yes, control flow changed, block might
2319                 have Bad() predecessors. */
2320                 set_irg_doms_inconsistent(irg);
2321         }
2322         return env.changes != 0;
2323 }  /* optimize_load_store */
2324
2325 ir_graph_pass_t *optimize_load_store_pass(const char *name)
2326 {
2327         return def_graph_pass_ret(name ? name : "ldst", optimize_load_store);
2328 }  /* optimize_load_store_pass */