nsz Git - libfirm/blob - ir/opt/ldstopt.c

   1 /*
   2  * Copyright (C) 1995-2008 University of Karlsruhe.  All right reserved.
   3  *
   4  * This file is part of libFirm.
   5  *
   6  * This file may be distributed and/or modified under the terms of the
   7  * GNU General Public License version 2 as published by the Free Software
   8  * Foundation and appearing in the file LICENSE.GPL included in the
   9  * packaging of this file.
  10  *
  11  * Licensees holding valid libFirm Professional Edition licenses may use
  12  * this file in accordance with the libFirm Commercial License.
  13  * Agreement provided with the Software.
  14  *
  15  * This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
  16  * WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  17  * PURPOSE.
  18  */
  19
  20 /**
  21  * @file
  22  * @brief   Load/Store optimizations.
  23  * @author  Michael Beck
  24  * @version $Id$
  25  */
  26 #ifdef HAVE_CONFIG_H
  27 # include "config.h"
  28 #endif
  29
  30 #include <string.h>
  31 #include <stdbool.h>
  32
  33 #include "iroptimize.h"
  34 #include "irnode_t.h"
  35 #include "irgraph_t.h"
  36 #include "irmode_t.h"
  37 #include "iropt_t.h"
  38 #include "ircons_t.h"
  39 #include "irgmod.h"
  40 #include "irgwalk.h"
  41 #include "irvrfy.h"
  42 #include "tv_t.h"
  43 #include "dbginfo_t.h"
  44 #include "iropt_dbg.h"
  45 #include "irflag_t.h"
  46 #include "array.h"
  47 #include "irhooks.h"
  48 #include "iredges.h"
  49 #include "irtools.h"
  50 #include "opt_polymorphy.h"
  51 #include "irmemory.h"
  52 #include "xmalloc.h"
  53 #include "irphase_t.h"
  54 #include "irgopt.h"
  55 #include "debug.h"
  56
  57 /** The debug handle. */
  58 DEBUG_ONLY(static firm_dbg_module_t *dbg;)
  59
  60 #ifdef DO_CACHEOPT
  61 #include "cacheopt/cachesim.h"
  62 #endif
  63
  64 #undef IMAX
  65 #define IMAX(a,b)       ((a) > (b) ? (a) : (b))
  66
  67 #define MAX_PROJ        IMAX(IMAX(pn_Load_max, pn_Store_max), pn_Call_max)
  68
  69 enum changes_t {
  70         DF_CHANGED = 1,       /**< data flow changed */
  71         CF_CHANGED = 2,       /**< control flow changed */
  72 };
  73
  74 /**
  75  * walker environment
  76  */
  77 typedef struct _walk_env_t {
  78         struct obstack obst;          /**< list of all stores */
  79         unsigned changes;             /**< a bitmask of graph changes */
  80 } walk_env_t;
  81
  82 /** A Load/Store info. */
  83 typedef struct _ldst_info_t {
  84         ir_node  *projs[MAX_PROJ];    /**< list of Proj's of this node */
  85         ir_node  *exc_block;          /**< the exception block if available */
  86         int      exc_idx;             /**< predecessor index in the exception block */
  87         unsigned visited;             /**< visited counter for breaking loops */
  88 } ldst_info_t;
  89
  90 /**
  91  * flags for control flow.
  92  */
  93 enum block_flags_t {
  94         BLOCK_HAS_COND = 1,      /**< Block has conditional control flow */
  95         BLOCK_HAS_EXC  = 2       /**< Block has exceptional control flow */
  96 };
  97
  98 /**
  99  * a Block info.
 100  */
 101 typedef struct _block_info_t {
 102         unsigned flags;               /**< flags for the block */
 103 } block_info_t;
 104
 105 /** the master visited flag for loop detection. */
 106 static unsigned master_visited = 0;
 107
 108 #define INC_MASTER()       ++master_visited
 109 #define MARK_NODE(info)    (info)->visited = master_visited
 110 #define NODE_VISITED(info) (info)->visited >= master_visited
 111
 112 /**
 113  * get the Load/Store info of a node
 114  */
 115 static ldst_info_t *get_ldst_info(ir_node *node, struct obstack *obst) {
 116         ldst_info_t *info = get_irn_link(node);
 117
 118         if (! info) {
 119                 info = obstack_alloc(obst, sizeof(*info));
 120                 memset(info, 0, sizeof(*info));
 121                 set_irn_link(node, info);
 122         }
 123         return info;
 124 }  /* get_ldst_info */
 125
 126 /**
 127  * get the Block info of a node
 128  */
 129 static block_info_t *get_block_info(ir_node *node, struct obstack *obst) {
 130         block_info_t *info = get_irn_link(node);
 131
 132         if (! info) {
 133                 info = obstack_alloc(obst, sizeof(*info));
 134                 memset(info, 0, sizeof(*info));
 135                 set_irn_link(node, info);
 136         }
 137         return info;
 138 }  /* get_block_info */
 139
 140 /**
 141  * update the projection info for a Load/Store
 142  */
 143 static unsigned update_projs(ldst_info_t *info, ir_node *proj)
 144 {
 145         long nr = get_Proj_proj(proj);
 146
 147         assert(0 <= nr && nr <= MAX_PROJ && "Wrong proj from LoadStore");
 148
 149         if (info->projs[nr]) {
 150                 /* there is already one, do CSE */
 151                 exchange(proj, info->projs[nr]);
 152                 return DF_CHANGED;
 153         }
 154         else {
 155                 info->projs[nr] = proj;
 156                 return 0;
 157         }
 158 }  /* update_projs */
 159
 160 /**
 161  * update the exception block info for a Load/Store node.
 162  *
 163  * @param info   the load/store info struct
 164  * @param block  the exception handler block for this load/store
 165  * @param pos    the control flow input of the block
 166  */
 167 static unsigned update_exc(ldst_info_t *info, ir_node *block, int pos)
 168 {
 169         assert(info->exc_block == NULL && "more than one exception block found");
 170
 171         info->exc_block = block;
 172         info->exc_idx   = pos;
 173         return 0;
 174 }  /* update_exc */
 175
 176 /** Return the number of uses of an address node */
 177 #define get_irn_n_uses(adr)     get_irn_n_edges(adr)
 178
 179 /**
 180  * walker, collects all Load/Store/Proj nodes
 181  *
 182  * walks from Start -> End
 183  */
 184 static void collect_nodes(ir_node *node, void *env)
 185 {
 186         ir_opcode   opcode = get_irn_opcode(node);
 187         ir_node     *pred, *blk, *pred_blk;
 188         ldst_info_t *ldst_info;
 189         walk_env_t  *wenv = env;
 190
 191         if (opcode == iro_Proj) {
 192                 pred   = get_Proj_pred(node);
 193                 opcode = get_irn_opcode(pred);
 194
 195                 if (opcode == iro_Load || opcode == iro_Store || opcode == iro_Call) {
 196                         ldst_info = get_ldst_info(pred, &wenv->obst);
 197
 198                         wenv->changes |= update_projs(ldst_info, node);
 199
 200                         /*
 201                          * Place the Proj's to the same block as the
 202                          * predecessor Load. This is always ok and prevents
 203                          * "non-SSA" form after optimizations if the Proj
 204                          * is in a wrong block.
 205                          */
 206                         blk      = get_nodes_block(node);
 207                         pred_blk = get_nodes_block(pred);
 208                         if (blk != pred_blk) {
 209                                 wenv->changes |= DF_CHANGED;
 210                                 set_nodes_block(node, pred_blk);
 211                         }
 212                 }
 213         } else if (opcode == iro_Block) {
 214                 int i;
 215
 216                 for (i = get_Block_n_cfgpreds(node) - 1; i >= 0; --i) {
 217                         ir_node      *pred_block, *proj;
 218                         block_info_t *bl_info;
 219                         int          is_exc = 0;
 220
 221                         pred = proj = get_Block_cfgpred(node, i);
 222
 223                         if (is_Proj(proj)) {
 224                                 pred   = get_Proj_pred(proj);
 225                                 is_exc = get_Proj_proj(proj) == pn_Generic_X_except;
 226                         }
 227
 228                         /* ignore Bad predecessors, they will be removed later */
 229                         if (is_Bad(pred))
 230                                 continue;
 231
 232                         pred_block = get_nodes_block(pred);
 233                         bl_info    = get_block_info(pred_block, &wenv->obst);
 234
 235                         if (is_fragile_op(pred) && is_exc)
 236                                 bl_info->flags |= BLOCK_HAS_EXC;
 237                         else if (is_irn_forking(pred))
 238                                 bl_info->flags |= BLOCK_HAS_COND;
 239
 240                         opcode = get_irn_opcode(pred);
 241                         if (is_exc && (opcode == iro_Load || opcode == iro_Store || opcode == iro_Call)) {
 242                                 ldst_info = get_ldst_info(pred, &wenv->obst);
 243
 244                                 wenv->changes |= update_exc(ldst_info, node, i);
 245                         }
 246                 }
 247         }
 248 }  /* collect_nodes */
 249
 250 /**
 251  * Returns an entity if the address ptr points to a constant one.
 252  *
 253  * @param ptr  the address
 254  *
 255  * @return an entity or NULL
 256  */
 257 static ir_entity *find_constant_entity(ir_node *ptr)
 258 {
 259         for (;;) {
 260                 if (is_SymConst(ptr) && get_SymConst_kind(ptr) == symconst_addr_ent) {
 261                         ir_entity *ent = get_SymConst_entity(ptr);
 262                         if (variability_constant == get_entity_variability(ent))
 263                                 return ent;
 264                         return NULL;
 265                 } else if (is_Sel(ptr)) {
 266                         ir_entity *ent = get_Sel_entity(ptr);
 267                         ir_type   *tp  = get_entity_owner(ent);
 268
 269                         /* Do not fiddle with polymorphism. */
 270                         if (is_Class_type(get_entity_owner(ent)) &&
 271                                 ((get_entity_n_overwrites(ent)    != 0) ||
 272                                 (get_entity_n_overwrittenby(ent) != 0)   ) )
 273                                 return NULL;
 274
 275                         if (is_Array_type(tp)) {
 276                                 /* check bounds */
 277                                 int i, n;
 278
 279                                 for (i = 0, n = get_Sel_n_indexs(ptr); i < n; ++i) {
 280                                         ir_node *bound;
 281                                         tarval *tlower, *tupper;
 282                                         ir_node *index = get_Sel_index(ptr, i);
 283                                         tarval *tv     = computed_value(index);
 284
 285                                         /* check if the index is constant */
 286                                         if (tv == tarval_bad)
 287                                                 return NULL;
 288
 289                                         bound  = get_array_lower_bound(tp, i);
 290                                         tlower = computed_value(bound);
 291                                         bound  = get_array_upper_bound(tp, i);
 292                                         tupper = computed_value(bound);
 293
 294                                         if (tlower == tarval_bad || tupper == tarval_bad)
 295                                                 return NULL;
 296
 297                                         if (tarval_cmp(tv, tlower) & pn_Cmp_Lt)
 298                                                 return NULL;
 299                                         if (tarval_cmp(tupper, tv) & pn_Cmp_Lt)
 300                                                 return NULL;
 301
 302                                         /* ok, bounds check finished */
 303                                 }
 304                         }
 305
 306                         if (variability_constant == get_entity_variability(ent))
 307                                 return ent;
 308
 309                         /* try next */
 310                         ptr = get_Sel_ptr(ptr);
 311                 } else if (is_Add(ptr)) {
 312                         ir_node *l = get_Add_left(ptr);
 313                         ir_node *r = get_Add_right(ptr);
 314
 315                         if (get_irn_mode(l) == get_irn_mode(ptr) && is_Const(r))
 316                                 ptr = l;
 317                         else if (get_irn_mode(r) == get_irn_mode(ptr) && is_Const(l))
 318                                 ptr = r;
 319                         else
 320                                 return NULL;
 321
 322                         /* for now, we support only one addition, reassoc should fold all others */
 323                         if (! is_SymConst(ptr) && !is_Sel(ptr))
 324                                 return NULL;
 325                 } else if (is_Sub(ptr)) {
 326                         ir_node *l = get_Sub_left(ptr);
 327                         ir_node *r = get_Sub_right(ptr);
 328
 329                         if (get_irn_mode(l) == get_irn_mode(ptr) &&     is_Const(r))
 330                                 ptr = l;
 331                         else
 332                                 return NULL;
 333                         /* for now, we support only one substraction, reassoc should fold all others */
 334                         if (! is_SymConst(ptr) && !is_Sel(ptr))
 335                                 return NULL;
 336                 } else
 337                         return NULL;
 338         }
 339 }  /* find_constant_entity */
 340
 341 /**
 342  * Return the Selection index of a Sel node from dimension n
 343  */
 344 static long get_Sel_array_index_long(ir_node *n, int dim) {
 345         ir_node *index = get_Sel_index(n, dim);
 346         assert(is_Const(index));
 347         return get_tarval_long(get_Const_tarval(index));
 348 }  /* get_Sel_array_index_long */
 349
 350 /**
 351  * Returns the accessed component graph path for an
 352  * node computing an address.
 353  *
 354  * @param ptr    the node computing the address
 355  * @param depth  current depth in steps upward from the root
 356  *               of the address
 357  */
 358 static compound_graph_path *rec_get_accessed_path(ir_node *ptr, int depth) {
 359         compound_graph_path *res = NULL;
 360         ir_entity           *root, *field, *ent;
 361         int                 path_len, pos, idx;
 362         tarval              *tv;
 363         ir_type             *tp;
 364
 365         if (is_SymConst(ptr)) {
 366                 /* a SymConst. If the depth is 0, this is an access to a global
 367                  * entity and we don't need a component path, else we know
 368                  * at least it's length.
 369                  */
 370                 assert(get_SymConst_kind(ptr) == symconst_addr_ent);
 371                 root = get_SymConst_entity(ptr);
 372                 res = (depth == 0) ? NULL : new_compound_graph_path(get_entity_type(root), depth);
 373         } else if (is_Sel(ptr)) {
 374                 /* it's a Sel, go up until we find the root */
 375                 res = rec_get_accessed_path(get_Sel_ptr(ptr), depth+1);
 376                 if (res == NULL)
 377                         return NULL;
 378
 379                 /* fill up the step in the path at the current position */
 380                 field    = get_Sel_entity(ptr);
 381                 path_len = get_compound_graph_path_length(res);
 382                 pos      = path_len - depth - 1;
 383                 set_compound_graph_path_node(res, pos, field);
 384
 385                 if (is_Array_type(get_entity_owner(field))) {
 386                         assert(get_Sel_n_indexs(ptr) == 1 && "multi dim arrays not implemented");
 387                         set_compound_graph_path_array_index(res, pos, get_Sel_array_index_long(ptr, 0));
 388                 }
 389         } else if (is_Add(ptr)) {
 390                 ir_node *l = get_Add_left(ptr);
 391                 ir_node *r = get_Add_right(ptr);
 392                 ir_mode *mode;
 393
 394                 if (is_Const(r)) {
 395                         ptr = l;
 396                         tv  = get_Const_tarval(r);
 397                 } else {
 398                         ptr = r;
 399                         tv  = get_Const_tarval(l);
 400                 }
 401 ptr_arith:
 402                 mode = get_tarval_mode(tv);
 403
 404                 /* ptr must be a Sel or a SymConst, this was checked in find_constant_entity() */
 405                 if (is_Sel(ptr)) {
 406                         field = get_Sel_entity(ptr);
 407                 } else {
 408                         field = get_SymConst_entity(ptr);
 409                 }
 410                 idx = 0;
 411                 for (ent = field;;) {
 412                         unsigned size;
 413                         tarval   *sz, *tv_index, *tlower, *tupper;
 414                         ir_node  *bound;
 415
 416                         tp = get_entity_type(ent);
 417                         if (! is_Array_type(tp))
 418                                 break;
 419                         ent = get_array_element_entity(tp);
 420                         size = get_type_size_bytes(get_entity_type(ent));
 421                         sz   = new_tarval_from_long(size, mode);
 422
 423                         tv_index = tarval_div(tv, sz);
 424                         tv       = tarval_mod(tv, sz);
 425
 426                         if (tv_index == tarval_bad || tv == tarval_bad)
 427                                 return NULL;
 428
 429                         assert(get_array_n_dimensions(tp) == 1 && "multiarrays not implemented");
 430                         bound  = get_array_lower_bound(tp, 0);
 431                         tlower = computed_value(bound);
 432                         bound  = get_array_upper_bound(tp, 0);
 433                         tupper = computed_value(bound);
 434
 435                         if (tlower == tarval_bad || tupper == tarval_bad)
 436                                 return NULL;
 437
 438                         if (tarval_cmp(tv_index, tlower) & pn_Cmp_Lt)
 439                                 return NULL;
 440                         if (tarval_cmp(tupper, tv_index) & pn_Cmp_Lt)
 441                                 return NULL;
 442
 443                         /* ok, bounds check finished */
 444                         ++idx;
 445                 }
 446                 if (! tarval_is_null(tv)) {
 447                         /* access to some struct/union member */
 448                         return NULL;
 449                 }
 450
 451                 /* should be at least ONE array */
 452                 if (idx == 0)
 453                         return NULL;
 454
 455                 res = rec_get_accessed_path(ptr, depth + idx);
 456                 if (res == NULL)
 457                         return NULL;
 458
 459                 path_len = get_compound_graph_path_length(res);
 460                 pos      = path_len - depth - idx;
 461
 462                 for (ent = field;;) {
 463                         unsigned size;
 464                         tarval   *sz, *tv_index;
 465                         long     index;
 466
 467                         tp = get_entity_type(ent);
 468                         if (! is_Array_type(tp))
 469                                 break;
 470                         ent = get_array_element_entity(tp);
 471                         set_compound_graph_path_node(res, pos, ent);
 472
 473                         size = get_type_size_bytes(get_entity_type(ent));
 474                         sz   = new_tarval_from_long(size, mode);
 475
 476                         tv_index = tarval_div(tv, sz);
 477                         tv       = tarval_mod(tv, sz);
 478
 479                         /* worked above, should work again */
 480                         assert(tv_index != tarval_bad && tv != tarval_bad);
 481
 482                         /* bounds already checked above */
 483                         index = get_tarval_long(tv_index);
 484                         set_compound_graph_path_array_index(res, pos, index);
 485                         ++pos;
 486                 }
 487         } else if (is_Sub(ptr)) {
 488                 ir_node *l = get_Sub_left(ptr);
 489                 ir_node *r = get_Sub_right(ptr);
 490
 491                 ptr = l;
 492                 tv  = get_Const_tarval(r);
 493                 tv  = tarval_neg(tv);
 494                 goto ptr_arith;
 495         }
 496         return res;
 497 }  /* rec_get_accessed_path */
 498
 499 /**
 500  * Returns an access path or NULL.  The access path is only
 501  * valid, if the graph is in phase_high and _no_ address computation is used.
 502  */
 503 static compound_graph_path *get_accessed_path(ir_node *ptr) {
 504         return rec_get_accessed_path(ptr, 0);
 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         path_entry       entry, *p;
 515         ir_entity        *ent, *field;
 516         ir_initializer_t *initializer;
 517         tarval           *tv;
 518         ir_type          *tp;
 519         unsigned         n;
 520
 521         entry.next = next;
 522         if (is_SymConst(ptr)) {
 523                 /* found the root */
 524                 ent         = get_SymConst_entity(ptr);
 525                 initializer = get_entity_initializer(ent);
 526                 for (p = next; p != NULL;) {
 527                         if (initializer->kind != IR_INITIALIZER_COMPOUND)
 528                                 return NULL;
 529                         n  = get_initializer_compound_n_entries(initializer);
 530                         tp = get_entity_type(ent);
 531
 532                         if (is_Array_type(tp)) {
 533                                 ent = get_array_element_entity(tp);
 534                                 if (ent != p->ent) {
 535                                         /* a missing [0] */
 536                                         if (0 >= n)
 537                                                 return NULL;
 538                                         initializer = get_initializer_compound_value(initializer, 0);
 539                                         continue;
 540                                 }
 541                         }
 542                         if (p->index >= n)
 543                                 return NULL;
 544                         initializer = get_initializer_compound_value(initializer, p->index);
 545
 546                         ent = p->ent;
 547                         p   = p->next;
 548                 }
 549                 tp = get_entity_type(ent);
 550                 while (is_Array_type(tp)) {
 551                         ent = get_array_element_entity(tp);
 552                         tp = get_entity_type(ent);
 553                         /* a missing [0] */
 554                         n  = get_initializer_compound_n_entries(initializer);
 555                         if (0 >= n)
 556                                 return NULL;
 557                         initializer = get_initializer_compound_value(initializer, 0);
 558                 }
 559
 560                 switch (initializer->kind) {
 561                 case IR_INITIALIZER_CONST:
 562                         return get_initializer_const_value(initializer);
 563                 case IR_INITIALIZER_TARVAL:
 564                 case IR_INITIALIZER_NULL:
 565                 default:
 566                         return NULL;
 567                 }
 568         } else if (is_Sel(ptr)) {
 569                 entry.ent = field = get_Sel_entity(ptr);
 570                 tp = get_entity_owner(field);
 571                 if (is_Array_type(tp)) {
 572                         assert(get_Sel_n_indexs(ptr) == 1 && "multi dim arrays not implemented");
 573                         entry.index = get_Sel_array_index_long(ptr, 0) - get_array_lower_bound_int(tp, 0);
 574                 } else {
 575                         int i, n_members = get_compound_n_members(tp);
 576                         for (i = 0; i < n_members; ++i) {
 577                                 if (get_compound_member(tp, i) == field)
 578                                         break;
 579                         }
 580                         if (i >= n_members) {
 581                                 /* not found: should NOT happen */
 582                                 return NULL;
 583                         }
 584                         entry.index = i;
 585                 }
 586                 return rec_find_compound_ent_value(get_Sel_ptr(ptr), &entry);
 587         }  else if (is_Add(ptr)) {
 588                 ir_node  *l = get_Add_left(ptr);
 589                 ir_node  *r = get_Add_right(ptr);
 590                 ir_mode  *mode;
 591                 unsigned pos;
 592
 593                 if (is_Const(r)) {
 594                         ptr = l;
 595                         tv  = get_Const_tarval(r);
 596                 } else {
 597                         ptr = r;
 598                         tv  = get_Const_tarval(l);
 599                 }
 600 ptr_arith:
 601                 mode = get_tarval_mode(tv);
 602
 603                 /* ptr must be a Sel or a SymConst, this was checked in find_constant_entity() */
 604                 if (is_Sel(ptr)) {
 605                         field = get_Sel_entity(ptr);
 606                 } else {
 607                         field = get_SymConst_entity(ptr);
 608                 }
 609
 610                 /* count needed entries */
 611                 pos = 0;
 612                 for (ent = field;;) {
 613                         tp = get_entity_type(ent);
 614                         if (! is_Array_type(tp))
 615                                 break;
 616                         ent = get_array_element_entity(tp);
 617                         ++pos;
 618                 }
 619                 /* should be at least ONE entry */
 620                 if (pos == 0)
 621                         return NULL;
 622
 623                 /* allocate the right number of entries */
 624                 NEW_ARR_A(path_entry, p, pos);
 625
 626                 /* fill them up */
 627                 pos = 0;
 628                 for (ent = field;;) {
 629                         unsigned size;
 630                         tarval   *sz, *tv_index, *tlower, *tupper;
 631                         long     index;
 632                         ir_node  *bound;
 633
 634                         tp = get_entity_type(ent);
 635                         if (! is_Array_type(tp))
 636                                 break;
 637                         ent = get_array_element_entity(tp);
 638                         p[pos].ent  = ent;
 639                         p[pos].next = &p[pos + 1];
 640
 641                         size = get_type_size_bytes(get_entity_type(ent));
 642                         sz   = new_tarval_from_long(size, mode);
 643
 644                         tv_index = tarval_div(tv, sz);
 645                         tv       = tarval_mod(tv, sz);
 646
 647                         if (tv_index == tarval_bad || tv == tarval_bad)
 648                                 return NULL;
 649
 650                         assert(get_array_n_dimensions(tp) == 1 && "multiarrays not implemented");
 651                         bound  = get_array_lower_bound(tp, 0);
 652                         tlower = computed_value(bound);
 653                         bound  = get_array_upper_bound(tp, 0);
 654                         tupper = computed_value(bound);
 655
 656                         if (tlower == tarval_bad || tupper == tarval_bad)
 657                                 return NULL;
 658
 659                         if (tarval_cmp(tv_index, tlower) & pn_Cmp_Lt)
 660                                 return NULL;
 661                         if (tarval_cmp(tupper, tv_index) & pn_Cmp_Lt)
 662                                 return NULL;
 663
 664                         /* ok, bounds check finished */
 665                         index = get_tarval_long(tv_index);
 666                         p[pos].index = index;
 667                         ++pos;
 668                 }
 669                 if (! tarval_is_null(tv)) {
 670                         /* hmm, wrong access */
 671                         return NULL;
 672                 }
 673                 p[pos - 1].next = next;
 674                 return rec_find_compound_ent_value(ptr, p);
 675         } else if (is_Sub(ptr)) {
 676                 ir_node *l = get_Sub_left(ptr);
 677                 ir_node *r = get_Sub_right(ptr);
 678
 679                 ptr = l;
 680                 tv  = get_Const_tarval(r);
 681                 tv  = tarval_neg(tv);
 682                 goto ptr_arith;
 683         }
 684         return NULL;
 685 }
 686
 687 static ir_node *find_compound_ent_value(ir_node *ptr) {
 688         return rec_find_compound_ent_value(ptr, NULL);
 689 }
 690
 691 /* forward */
 692 static void reduce_adr_usage(ir_node *ptr);
 693
 694 /**
 695  * Update a Load that may lost it's usage.
 696  */
 697 static void handle_load_update(ir_node *load) {
 698         ldst_info_t *info = get_irn_link(load);
 699
 700         /* do NOT touch volatile loads for now */
 701         if (get_Load_volatility(load) == volatility_is_volatile)
 702                 return;
 703
 704         if (! info->projs[pn_Load_res] && ! info->projs[pn_Load_X_except]) {
 705                 ir_node *ptr = get_Load_ptr(load);
 706                 ir_node *mem = get_Load_mem(load);
 707
 708                 /* a Load which value is neither used nor exception checked, remove it */
 709                 exchange(info->projs[pn_Load_M], mem);
 710                 if (info->projs[pn_Load_X_regular])
 711                         exchange(info->projs[pn_Load_X_regular], new_r_Jmp(current_ir_graph, get_nodes_block(load)));
 712                 kill_node(load);
 713                 reduce_adr_usage(ptr);
 714         }
 715 }  /* handle_load_update */
 716
 717 /**
 718  * A Use of an address node is vanished. Check if this was a Proj
 719  * node and update the counters.
 720  */
 721 static void reduce_adr_usage(ir_node *ptr) {
 722         if (is_Proj(ptr)) {
 723                 if (get_irn_n_edges(ptr) <= 0) {
 724                         /* this Proj is dead now */
 725                         ir_node *pred = get_Proj_pred(ptr);
 726
 727                         if (is_Load(pred)) {
 728                                 ldst_info_t *info = get_irn_link(pred);
 729                                 info->projs[get_Proj_proj(ptr)] = NULL;
 730
 731                                 /* this node lost it's result proj, handle that */
 732                                 handle_load_update(pred);
 733                         }
 734                 }
 735         }
 736 }  /* reduce_adr_usage */
 737
 738 /**
 739  * Check, if an already existing value of mode old_mode can be converted
 740  * into the needed one new_mode without loss.
 741  */
 742 static int can_use_stored_value(ir_mode *old_mode, ir_mode *new_mode) {
 743         if (old_mode == new_mode)
 744                 return 1;
 745
 746         /* if both modes are two-complement ones, we can always convert the
 747            Stored value into the needed one. */
 748         if (get_mode_size_bits(old_mode) >= get_mode_size_bits(new_mode) &&
 749                   get_mode_arithmetic(old_mode) == irma_twos_complement &&
 750                   get_mode_arithmetic(new_mode) == irma_twos_complement)
 751                 return 1;
 752         return 0;
 753 }  /* can_use_stored_value */
 754
 755 /**
 756  * Check whether a Call is at least pure, ie. does only read memory.
 757  */
 758 static unsigned is_Call_pure(ir_node *call) {
 759         ir_type *call_tp = get_Call_type(call);
 760         unsigned prop = get_method_additional_properties(call_tp);
 761
 762         /* check first the call type */
 763         if ((prop & (mtp_property_const|mtp_property_pure)) == 0) {
 764                 /* try the called entity */
 765                 ir_node *ptr = get_Call_ptr(call);
 766
 767                 if (is_Global(ptr)) {
 768                         ir_entity *ent = get_Global_entity(ptr);
 769
 770                         prop = get_entity_additional_properties(ent);
 771                 }
 772         }
 773         return (prop & (mtp_property_const|mtp_property_pure)) != 0;
 774 }  /* is_Call_pure */
 775
 776 static ir_node *get_base_ptr(ir_node *ptr)
 777 {
 778         while (is_Add(ptr) && is_Const(get_Add_right(ptr))) {
 779                 ptr = get_Add_left(ptr);
 780         }
 781
 782         return ptr;
 783 }
 784
 785 static long get_base_offset(ir_node *ptr)
 786 {
 787         /* TODO: long might not be enough, we should probably use some tarval thingy... */
 788         long offset = 0;
 789         while (is_Add(ptr)) {
 790                 ir_node *right = get_Add_right(ptr);
 791                 if (!is_Const(right))
 792                         break;
 793                 offset += get_tarval_long(get_Const_tarval(right));
 794                 ptr = get_Add_left(ptr);
 795         }
 796
 797         return offset;
 798 }
 799
 800 static int try_load_store(ir_node *load,
 801                 ir_node *load_base_ptr, long load_offset, ir_node *store)
 802 {
 803         ldst_info_t *info;
 804         ir_node *store_ptr      = get_Store_ptr(store);
 805         ir_node *store_base_ptr = get_base_ptr(store_ptr);
 806         ir_node *store_value;
 807         ir_mode *store_mode;
 808         ir_node *load_ptr;
 809         ir_mode *load_mode;
 810         long     store_offset   = get_base_offset(store_ptr);
 811         long     load_mode_len;
 812         long     store_mode_len;
 813         long     delta;
 814         int      res;
 815
 816         if (load_base_ptr != store_base_ptr)
 817                 return 0;
 818
 819         load_mode     = get_Load_mode(load);
 820         load_mode_len = get_mode_size_bytes(load_mode);
 821         store_mode     = get_irn_mode(get_Store_value(store));
 822         store_mode_len = get_mode_size_bytes(store_mode);
 823
 824         delta         = load_offset - store_offset;
 825         if (delta < 0 || delta >= store_mode_len)
 826                 return 0;
 827
 828         if (store_mode_len - delta > load_mode_len)
 829                 return 0;
 830
 831         store_value = get_Store_value(store);
 832         DBG_OPT_RAW(load, store_value);
 833
 834         /* produce a shift to adjust offset delta */
 835         if (delta > 0) {
 836                 ir_node *cnst = new_r_Const_long(current_ir_graph,
 837                                 get_irg_start_block(current_ir_graph), mode_Iu, delta * 8);
 838                 store_value = new_r_Shr(current_ir_graph, get_nodes_block(load),
 839                                         store_value, cnst, store_mode);
 840         }
 841
 842         /* add an convert if needed */
 843         if (store_mode != load_mode) {
 844                 store_value = new_r_Conv(current_ir_graph, get_nodes_block(load),
 845                                          store_value, load_mode);
 846         }
 847
 848         info = get_irn_link(load);
 849         if (info->projs[pn_Load_M])
 850                 exchange(info->projs[pn_Load_M], get_Load_mem(load));
 851
 852         res = 0;
 853         /* no exception */
 854         if (info->projs[pn_Load_X_except]) {
 855                 exchange( info->projs[pn_Load_X_except], new_Bad());
 856                 res |= CF_CHANGED;
 857         }
 858         if (info->projs[pn_Load_X_regular]) {
 859                 exchange( info->projs[pn_Load_X_regular], new_r_Jmp(current_ir_graph, get_nodes_block(load)));
 860                 res |= CF_CHANGED;
 861         }
 862
 863         if (info->projs[pn_Load_res])
 864                 exchange(info->projs[pn_Load_res], store_value);
 865
 866         load_ptr = get_Load_ptr(load);
 867         kill_node(load);
 868         reduce_adr_usage(load_ptr);
 869         return res | DF_CHANGED;
 870 }
 871
 872 /**
 873  * Follow the memory chain as long as there are only Loads,
 874  * alias free Stores, and constant Calls and try to replace the
 875  * current Load by a previous ones.
 876  * Note that in unreachable loops it might happen that we reach
 877  * load again, as well as we can fall into a cycle.
 878  * We break such cycles using a special visited flag.
 879  *
 880  * INC_MASTER() must be called before dive into
 881  */
 882 static unsigned follow_Mem_chain(ir_node *load, ir_node *curr) {
 883         unsigned res = 0;
 884         ldst_info_t *info = get_irn_link(load);
 885         ir_node *pred;
 886         ir_node *ptr       = get_Load_ptr(load);
 887         ir_node *mem       = get_Load_mem(load);
 888         ir_mode *load_mode = get_Load_mode(load);
 889         ir_node *base_ptr  = get_base_ptr(ptr);
 890         long     load_offset = get_base_offset(ptr);
 891
 892         for (pred = curr; load != pred; ) {
 893                 ldst_info_t *pred_info = get_irn_link(pred);
 894
 895                 /*
 896                  * a Load immediately after a Store -- a read after write.
 897                  * We may remove the Load, if both Load & Store does not have an
 898                  * exception handler OR they are in the same MacroBlock. In the latter
 899                  * case the Load cannot throw an exception when the previous Store was
 900                  * quiet.
 901                  *
 902                  * Why we need to check for Store Exception? If the Store cannot
 903                  * be executed (ROM) the exception handler might simply jump into
 904                  * the load MacroBlock :-(
 905                  * We could make it a little bit better if we would know that the
 906                  * exception handler of the Store jumps directly to the end...
 907                  */
 908                 if (is_Store(pred) && ((pred_info->projs[pn_Store_X_except] == NULL
 909                                 && info->projs[pn_Load_X_except] == NULL)
 910                                 || get_nodes_MacroBlock(load) == get_nodes_MacroBlock(pred)))
 911                 {
 912                         int changes
 913                                 = try_load_store(load, base_ptr, load_offset, pred);
 914                         if (changes != 0) {
 915                                 return res | changes;
 916                         }
 917                 } else if (is_Load(pred) && get_Load_ptr(pred) == ptr &&
 918                            can_use_stored_value(get_Load_mode(pred), load_mode)) {
 919                         /*
 920                          * a Load after a Load -- a read after read.
 921                          * We may remove the second Load, if it does not have an exception handler
 922                          * OR they are in the same MacroBlock. In the later case the Load cannot
 923                          * throw an exception when the previous Load was quiet.
 924                          *
 925                          * Here, there is no need to check if the previous Load has an exception
 926                          * hander because they would have exact the same exception...
 927                          */
 928                         if (info->projs[pn_Load_X_except] == NULL || get_nodes_MacroBlock(load) == get_nodes_MacroBlock(pred)) {
 929                                 ir_node *value;
 930
 931                                 DBG_OPT_RAR(load, pred);
 932
 933                                 /* the result is used */
 934                                 if (info->projs[pn_Load_res]) {
 935                                         if (pred_info->projs[pn_Load_res] == NULL) {
 936                                                 /* create a new Proj again */
 937                                                 pred_info->projs[pn_Load_res] = new_r_Proj(current_ir_graph, get_nodes_block(pred), pred, get_Load_mode(pred), pn_Load_res);
 938                                         }
 939                                         value = pred_info->projs[pn_Load_res];
 940
 941                                         /* add an convert if needed */
 942                                         if (get_Load_mode(pred) != load_mode) {
 943                                                 value = new_r_Conv(current_ir_graph, get_nodes_block(load), value, load_mode);
 944                                         }
 945
 946                                         exchange(info->projs[pn_Load_res], value);
 947                                 }
 948
 949                                 if (info->projs[pn_Load_M])
 950                                         exchange(info->projs[pn_Load_M], mem);
 951
 952                                 /* no exception */
 953                                 if (info->projs[pn_Load_X_except]) {
 954                                         exchange(info->projs[pn_Load_X_except], new_Bad());
 955                                         res |= CF_CHANGED;
 956                                 }
 957                                 if (info->projs[pn_Load_X_regular]) {
 958                                         exchange( info->projs[pn_Load_X_regular], new_r_Jmp(current_ir_graph, get_nodes_block(load)));
 959                                         res |= CF_CHANGED;
 960                                 }
 961
 962                                 kill_node(load);
 963                                 reduce_adr_usage(ptr);
 964                                 return res |= DF_CHANGED;
 965                         }
 966                 }
 967
 968                 if (is_Store(pred)) {
 969                         /* check if we can pass through this store */
 970                         ir_alias_relation rel = get_alias_relation(
 971                                 current_ir_graph,
 972                                 get_Store_ptr(pred),
 973                                 get_irn_mode(get_Store_value(pred)),
 974                                 ptr, load_mode);
 975                         /* if the might be an alias, we cannot pass this Store */
 976                         if (rel != ir_no_alias)
 977                                 break;
 978                         pred = skip_Proj(get_Store_mem(pred));
 979                 } else if (is_Load(pred)) {
 980                         pred = skip_Proj(get_Load_mem(pred));
 981                 } else if (is_Call(pred)) {
 982                         if (is_Call_pure(pred)) {
 983                                 /* The called graph is at least pure, so there are no Store's
 984                                    in it. We can handle it like a Load and skip it. */
 985                                 pred = skip_Proj(get_Call_mem(pred));
 986                         } else {
 987                                 /* there might be Store's in the graph, stop here */
 988                                 break;
 989                         }
 990                 } else {
 991                         /* follow only Load chains */
 992                         break;
 993                 }
 994
 995                 /* check for cycles */
 996                 if (NODE_VISITED(pred_info))
 997                         break;
 998                 MARK_NODE(pred_info);
 999         }
1000
1001         if (is_Sync(pred)) {
1002                 int i;
1003
1004                 /* handle all Sync predecessors */
1005                 for (i = get_Sync_n_preds(pred) - 1; i >= 0; --i) {
1006                         res |= follow_Mem_chain(load, skip_Proj(get_Sync_pred(pred, i)));
1007                         if (res)
1008                                 return res;
1009                 }
1010         }
1011
1012         return res;
1013 }  /* follow_Mem_chain */
1014
1015 /*
1016  * Check if we can replace the load by a given const from
1017  * the const code irg.
1018  */
1019 ir_node *can_replace_load_by_const(const ir_node *load, ir_node *c) {
1020         ir_mode *c_mode = get_irn_mode(c);
1021         ir_mode *l_mode = get_Load_mode(load);
1022         ir_node *res    = NULL;
1023
1024         if (c_mode != l_mode) {
1025                 /* check, if the mode matches OR can be easily converted info */
1026                 if (is_reinterpret_cast(c_mode, l_mode)) {
1027                         /* we can safely cast */
1028                         dbg_info *dbg   = get_irn_dbg_info(load);
1029                         ir_node  *block = get_nodes_block(load);
1030
1031                         /* copy the value from the const code irg and cast it */
1032                         res = copy_const_value(dbg, c);
1033                         res = new_rd_Conv(dbg, current_ir_graph, block, res, l_mode);
1034                 }
1035         } else {
1036                 /* copy the value from the const code irg */
1037                 res = copy_const_value(get_irn_dbg_info(load), c);
1038         }
1039         return res;
1040 }  /* can_replace_load_by_const */
1041
1042 /**
1043  * optimize a Load
1044  *
1045  * @param load  the Load node
1046  */
1047 static unsigned optimize_load(ir_node *load)
1048 {
1049         ldst_info_t *info = get_irn_link(load);
1050         ir_node *mem, *ptr, *value;
1051         ir_entity *ent;
1052         unsigned res = 0;
1053
1054         /* do NOT touch volatile loads for now */
1055         if (get_Load_volatility(load) == volatility_is_volatile)
1056                 return 0;
1057
1058         /* the address of the load to be optimized */
1059         ptr = get_Load_ptr(load);
1060
1061         /*
1062          * Check if we can remove the exception from a Load:
1063          * This can be done, if the address is from an Sel(Alloc) and
1064          * the Sel type is a subtype of the allocated type.
1065          *
1066          * This optimizes some often used OO constructs,
1067          * like x = new O; x->t;
1068          */
1069         if (info->projs[pn_Load_X_except]) {
1070                 ir_node *addr = ptr;
1071
1072                 /* find base address */
1073                 while (is_Sel(addr))
1074                         addr = get_Sel_ptr(addr);
1075                 if (is_Alloc(skip_Proj(skip_Cast(addr)))) {
1076                         /* simple case: a direct load after an Alloc. Firm Alloc throw
1077                          * an exception in case of out-of-memory. So, there is no way for an
1078                          * exception in this load.
1079                          * This code is constructed by the "exception lowering" in the Jack compiler.
1080                          */
1081                         exchange(info->projs[pn_Load_X_except], new_Bad());
1082                         info->projs[pn_Load_X_except] = NULL;
1083                         exchange(info->projs[pn_Load_X_regular], new_r_Jmp(current_ir_graph, get_nodes_block(load)));
1084                         info->projs[pn_Load_X_regular] = NULL;
1085                         res |= CF_CHANGED;
1086                 }
1087         }
1088
1089         /* The mem of the Load. Must still be returned after optimization. */
1090         mem  = get_Load_mem(load);
1091
1092         if (! info->projs[pn_Load_res] && ! info->projs[pn_Load_X_except]) {
1093                 /* a Load which value is neither used nor exception checked, remove it */
1094                 exchange(info->projs[pn_Load_M], mem);
1095
1096                 if (info->projs[pn_Load_X_regular]) {
1097                         /* should not happen, but if it does, remove it */
1098                         exchange(info->projs[pn_Load_X_regular], new_r_Jmp(current_ir_graph, get_nodes_block(load)));
1099                         res |= CF_CHANGED;
1100                 }
1101                 kill_node(load);
1102                 reduce_adr_usage(ptr);
1103                 return res | DF_CHANGED;
1104         }
1105
1106         /* Load from a constant polymorphic field, where we can resolve
1107            polymorphism. */
1108         value = transform_polymorph_Load(load);
1109         if (value == load) {
1110                 value = NULL;
1111                 /* check if we can determine the entity that will be loaded */
1112                 ent = find_constant_entity(ptr);
1113                 if (ent != NULL) {
1114                         if ((allocation_static == get_entity_allocation(ent)) &&
1115                                 (visibility_external_allocated != get_entity_visibility(ent))) {
1116                                 /* a static allocation that is not external: there should be NO exception
1117                                  * when loading even if we cannot replace the load itself. */
1118
1119                                 /* no exception, clear the info field as it might be checked later again */
1120                                 if (info->projs[pn_Load_X_except]) {
1121                                         exchange(info->projs[pn_Load_X_except], new_Bad());
1122                                         info->projs[pn_Load_X_except] = NULL;
1123                                         res |= CF_CHANGED;
1124                                 }
1125                                 if (info->projs[pn_Load_X_regular]) {
1126                                         exchange(info->projs[pn_Load_X_regular], new_r_Jmp(current_ir_graph, get_nodes_block(load)));
1127                                         info->projs[pn_Load_X_regular] = NULL;
1128                                         res |= CF_CHANGED;
1129                                 }
1130
1131                                 if (variability_constant == get_entity_variability(ent)) {
1132                                         if (is_atomic_entity(ent)) {
1133                                                 /* Might not be atomic after
1134                                                    lowering of Sels.  In this
1135                                                    case we could also load, but
1136                                                    it's more complicated. */
1137                                                 /* more simpler case: we load the content of a constant value:
1138                                                  * replace it by the constant itself
1139                                                  */
1140                                                 value = get_atomic_ent_value(ent);
1141                                         } else {
1142                                                 if (ent->has_initializer) {
1143                                                         /* new style initializer */
1144                                                         value = find_compound_ent_value(ptr);
1145                                                 } else {
1146                                                         /* old style initializer */
1147                                                         compound_graph_path *path = get_accessed_path(ptr);
1148
1149                                                         if (path != NULL) {
1150                                                                 assert(is_proper_compound_graph_path(path, get_compound_graph_path_length(path)-1));
1151
1152                                                                 value = get_compound_ent_value_by_path(ent, path);
1153                                                                 free_compound_graph_path(path);
1154                                                         }
1155                                                 }
1156                                         }
1157                                         if (value != NULL)
1158                                                 value = can_replace_load_by_const(load, value);
1159                                 }
1160                         }
1161                 }
1162         }
1163         if (value != NULL) {
1164                 /* we completely replace the load by this value */
1165                 if (info->projs[pn_Load_X_except]) {
1166                         exchange(info->projs[pn_Load_X_except], new_Bad());
1167                         info->projs[pn_Load_X_except] = NULL;
1168                         res |= CF_CHANGED;
1169                 }
1170                 if (info->projs[pn_Load_X_regular]) {
1171                         exchange(info->projs[pn_Load_X_regular], new_r_Jmp(current_ir_graph, get_nodes_block(load)));
1172                         info->projs[pn_Load_X_regular] = NULL;
1173                         res |= CF_CHANGED;
1174                 }
1175                 if (info->projs[pn_Load_M]) {
1176                         exchange(info->projs[pn_Load_M], mem);
1177                         res |= DF_CHANGED;
1178                 }
1179                 if (info->projs[pn_Load_res]) {
1180                         exchange(info->projs[pn_Load_res], value);
1181                         res |= DF_CHANGED;
1182                 }
1183                 kill_node(load);
1184                 reduce_adr_usage(ptr);
1185                 return res;
1186         }
1187
1188         /* Check, if the address of this load is used more than once.
1189          * If not, this load cannot be removed in any case. */
1190         if (get_irn_n_uses(ptr) <= 1 && get_irn_n_uses(get_base_ptr(ptr)) <= 1)
1191                 return res;
1192
1193         /*
1194          * follow the memory chain as long as there are only Loads
1195          * and try to replace current Load or Store by a previous one.
1196          * Note that in unreachable loops it might happen that we reach
1197          * load again, as well as we can fall into a cycle.
1198          * We break such cycles using a special visited flag.
1199          */
1200         INC_MASTER();
1201         res = follow_Mem_chain(load, skip_Proj(mem));
1202         return res;
1203 }  /* optimize_load */
1204
1205 /**
1206  * Check whether a value of mode new_mode would completely overwrite a value
1207  * of mode old_mode in memory.
1208  */
1209 static int is_completely_overwritten(ir_mode *old_mode, ir_mode *new_mode)
1210 {
1211         return get_mode_size_bits(new_mode) >= get_mode_size_bits(old_mode);
1212 }  /* is_completely_overwritten */
1213
1214 /**
1215  * follow the memory chain as long as there are only Loads and alias free Stores.
1216  *
1217  * INC_MASTER() must be called before dive into
1218  */
1219 static unsigned follow_Mem_chain_for_Store(ir_node *store, ir_node *curr) {
1220         unsigned res = 0;
1221         ldst_info_t *info = get_irn_link(store);
1222         ir_node *pred;
1223         ir_node *ptr = get_Store_ptr(store);
1224         ir_node *mem = get_Store_mem(store);
1225         ir_node *value = get_Store_value(store);
1226         ir_mode *mode  = get_irn_mode(value);
1227         ir_node *block = get_nodes_block(store);
1228         ir_node *mblk  = get_Block_MacroBlock(block);
1229
1230         for (pred = curr; pred != store;) {
1231                 ldst_info_t *pred_info = get_irn_link(pred);
1232
1233                 /*
1234                  * BEWARE: one might think that checking the modes is useless, because
1235                  * if the pointers are identical, they refer to the same object.
1236                  * This is only true in strong typed languages, not is C were the following
1237                  * is possible *(ir_type1 *)p = a; *(ir_type2 *)p = b ...
1238                  * However, if the mode that is written have a bigger  or equal size the the old
1239                  * one, the old value is completely overwritten and can be killed ...
1240                  */
1241                 if (is_Store(pred) && get_Store_ptr(pred) == ptr &&
1242                     get_nodes_MacroBlock(pred) == mblk &&
1243                     is_completely_overwritten(get_irn_mode(get_Store_value(pred)), mode)) {
1244                         /*
1245                          * a Store after a Store in the same MacroBlock -- a write after write.
1246                          * We may remove the first Store, if it does not have an exception handler.
1247                          *
1248                          * TODO: What, if both have the same exception handler ???
1249                          */
1250                         if (get_Store_volatility(pred) != volatility_is_volatile && !pred_info->projs[pn_Store_X_except]) {
1251                                 DBG_OPT_WAW(pred, store);
1252                                 exchange(pred_info->projs[pn_Store_M], get_Store_mem(pred));
1253                                 kill_node(pred);
1254                                 reduce_adr_usage(ptr);
1255                                 return DF_CHANGED;
1256                         }
1257                 } else if (is_Load(pred) && get_Load_ptr(pred) == ptr &&
1258                            value == pred_info->projs[pn_Load_res]) {
1259                         /*
1260                          * a Store of a value just loaded from the same address
1261                          * -- a write after read.
1262                          * We may remove the Store, if it does not have an exception
1263                          * handler.
1264                          */
1265                         if (! info->projs[pn_Store_X_except]) {
1266                                 DBG_OPT_WAR(store, pred);
1267                                 exchange(info->projs[pn_Store_M], mem);
1268                                 kill_node(store);
1269                                 reduce_adr_usage(ptr);
1270                                 return DF_CHANGED;
1271                         }
1272                 }
1273
1274                 if (is_Store(pred)) {
1275                         /* check if we can pass through this store */
1276                         ir_alias_relation rel = get_alias_relation(
1277                                 current_ir_graph,
1278                                 get_Store_ptr(pred),
1279                                 get_irn_mode(get_Store_value(pred)),
1280                                 ptr, mode);
1281                         /* if the might be an alias, we cannot pass this Store */
1282                         if (rel != ir_no_alias)
1283                                 break;
1284                         pred = skip_Proj(get_Store_mem(pred));
1285                 } else if (is_Load(pred)) {
1286                         ir_alias_relation rel = get_alias_relation(
1287                                 current_ir_graph, get_Load_ptr(pred), get_Load_mode(pred),
1288                                 ptr, mode);
1289                         if (rel != ir_no_alias)
1290                                 break;
1291
1292                         pred = skip_Proj(get_Load_mem(pred));
1293                 } else {
1294                         /* follow only Load chains */
1295                         break;
1296                 }
1297
1298                 /* check for cycles */
1299                 if (NODE_VISITED(pred_info))
1300                         break;
1301                 MARK_NODE(pred_info);
1302         }
1303
1304         if (is_Sync(pred)) {
1305                 int i;
1306
1307                 /* handle all Sync predecessors */
1308                 for (i = get_Sync_n_preds(pred) - 1; i >= 0; --i) {
1309                         res |= follow_Mem_chain_for_Store(store, skip_Proj(get_Sync_pred(pred, i)));
1310                         if (res)
1311                                 break;
1312                 }
1313         }
1314         return res;
1315 }  /* follow_Mem_chain_for_Store */
1316
1317 /**
1318  * optimize a Store
1319  *
1320  * @param store  the Store node
1321  */
1322 static unsigned optimize_store(ir_node *store) {
1323         ir_node *ptr, *mem;
1324
1325         if (get_Store_volatility(store) == volatility_is_volatile)
1326                 return 0;
1327
1328         ptr = get_Store_ptr(store);
1329
1330         /* Check, if the address of this Store is used more than once.
1331          * If not, this Store cannot be removed in any case. */
1332         if (get_irn_n_uses(ptr) <= 1)
1333                 return 0;
1334
1335         mem = get_Store_mem(store);
1336
1337         /* follow the memory chain as long as there are only Loads */
1338         INC_MASTER();
1339
1340         return follow_Mem_chain_for_Store(store, skip_Proj(mem));
1341 }  /* optimize_store */
1342
1343 /**
1344  * walker, optimizes Phi after Stores to identical places:
1345  * Does the following optimization:
1346  * @verbatim
1347  *
1348  *   val1   val2   val3          val1  val2  val3
1349  *    |      |      |               \    |    /
1350  *  Store  Store  Store              \   |   /
1351  *      \    |    /                   PhiData
1352  *       \   |   /                       |
1353  *        \  |  /                      Store
1354  *          PhiM
1355  *
1356  * @endverbatim
1357  * This reduces the number of stores and allows for predicated execution.
1358  * Moves Stores back to the end of a function which may be bad.
1359  *
1360  * This is only possible if the predecessor blocks have only one successor.
1361  */
1362 static unsigned optimize_phi(ir_node *phi, walk_env_t *wenv)
1363 {
1364         int i, n;
1365         ir_node *store, *old_store, *ptr, *block, *phi_block, *phiM, *phiD, *exc, *projM;
1366         ir_mode *mode;
1367         ir_node **inM, **inD, **projMs;
1368         int *idx;
1369         dbg_info *db = NULL;
1370         ldst_info_t *info;
1371         block_info_t *bl_info;
1372         unsigned res = 0;
1373
1374         /* Must be a memory Phi */
1375         if (get_irn_mode(phi) != mode_M)
1376                 return 0;
1377
1378         n = get_Phi_n_preds(phi);
1379         if (n <= 0)
1380                 return 0;
1381
1382         /* must be only one user */
1383         projM = get_Phi_pred(phi, 0);
1384         if (get_irn_n_edges(projM) != 1)
1385                 return 0;
1386
1387         store = skip_Proj(projM);
1388         old_store = store;
1389         if (!is_Store(store))
1390                 return 0;
1391
1392         block = get_nodes_block(store);
1393
1394         /* abort on dead blocks */
1395         if (is_Block_dead(block))
1396                 return 0;
1397
1398         /* check if the block is post dominated by Phi-block
1399            and has no exception exit */
1400         bl_info = get_irn_link(block);
1401         if (bl_info->flags & BLOCK_HAS_EXC)
1402                 return 0;
1403
1404         phi_block = get_nodes_block(phi);
1405         if (! block_strictly_postdominates(phi_block, block))
1406                 return 0;
1407
1408         /* this is the address of the store */
1409         ptr  = get_Store_ptr(store);
1410         mode = get_irn_mode(get_Store_value(store));
1411         info = get_irn_link(store);
1412         exc  = info->exc_block;
1413
1414         for (i = 1; i < n; ++i) {
1415                 ir_node *pred = get_Phi_pred(phi, i);
1416
1417                 if (get_irn_n_edges(pred) != 1)
1418                         return 0;
1419
1420                 pred = skip_Proj(pred);
1421                 if (!is_Store(pred))
1422                         return 0;
1423
1424                 if (ptr != get_Store_ptr(pred) || mode != get_irn_mode(get_Store_value(pred)))
1425                         return 0;
1426
1427                 info = get_irn_link(pred);
1428
1429                 /* check, if all stores have the same exception flow */
1430                 if (exc != info->exc_block)
1431                         return 0;
1432
1433                 /* abort on dead blocks */
1434                 block = get_nodes_block(pred);
1435                 if (is_Block_dead(block))
1436                         return 0;
1437
1438                 /* check if the block is post dominated by Phi-block
1439                    and has no exception exit. Note that block must be different from
1440                    Phi-block, else we would move a Store from end End of a block to its
1441                    Start... */
1442                 bl_info = get_irn_link(block);
1443                 if (bl_info->flags & BLOCK_HAS_EXC)
1444                         return 0;
1445                 if (block == phi_block || ! block_postdominates(phi_block, block))
1446                         return 0;
1447         }
1448
1449         /*
1450          * ok, when we are here, we found all predecessors of a Phi that
1451          * are Stores to the same address and size. That means whatever
1452          * we do before we enter the block of the Phi, we do a Store.
1453          * So, we can move the Store to the current block:
1454          *
1455          *   val1    val2    val3          val1  val2  val3
1456          *    |       |       |               \    |    /
1457          * | Str | | Str | | Str |             \   |   /
1458          *      \     |     /                   PhiData
1459          *       \    |    /                       |
1460          *        \   |   /                       Str
1461          *           PhiM
1462          *
1463          * Is only allowed if the predecessor blocks have only one successor.
1464          */
1465
1466         NEW_ARR_A(ir_node *, projMs, n);
1467         NEW_ARR_A(ir_node *, inM, n);
1468         NEW_ARR_A(ir_node *, inD, n);
1469         NEW_ARR_A(int, idx, n);
1470
1471         /* Prepare: Collect all Store nodes.  We must do this
1472            first because we otherwise may loose a store when exchanging its
1473            memory Proj.
1474          */
1475         for (i = n - 1; i >= 0; --i) {
1476                 ir_node *store;
1477
1478                 projMs[i] = get_Phi_pred(phi, i);
1479                 assert(is_Proj(projMs[i]));
1480
1481                 store = get_Proj_pred(projMs[i]);
1482                 info  = get_irn_link(store);
1483
1484                 inM[i] = get_Store_mem(store);
1485                 inD[i] = get_Store_value(store);
1486                 idx[i] = info->exc_idx;
1487         }
1488         block = get_nodes_block(phi);
1489
1490         /* second step: create a new memory Phi */
1491         phiM = new_rd_Phi(get_irn_dbg_info(phi), current_ir_graph, block, n, inM, mode_M);
1492
1493         /* third step: create a new data Phi */
1494         phiD = new_rd_Phi(get_irn_dbg_info(phi), current_ir_graph, block, n, inD, mode);
1495
1496         /* rewire memory and kill the node */
1497         for (i = n - 1; i >= 0; --i) {
1498                 ir_node *proj  = projMs[i];
1499
1500                 if(is_Proj(proj)) {
1501                         ir_node *store = get_Proj_pred(proj);
1502                         exchange(proj, inM[i]);
1503                         kill_node(store);
1504                 }
1505         }
1506
1507         /* fourth step: create the Store */
1508         store = new_rd_Store(db, current_ir_graph, block, phiM, ptr, phiD);
1509 #ifdef DO_CACHEOPT
1510         co_set_irn_name(store, co_get_irn_ident(old_store));
1511 #endif
1512
1513         projM = new_rd_Proj(NULL, current_ir_graph, block, store, mode_M, pn_Store_M);
1514
1515         info = get_ldst_info(store, &wenv->obst);
1516         info->projs[pn_Store_M] = projM;
1517
1518         /* fifths step: repair exception flow */
1519         if (exc) {
1520                 ir_node *projX = new_rd_Proj(NULL, current_ir_graph, block, store, mode_X, pn_Store_X_except);
1521
1522                 info->projs[pn_Store_X_except] = projX;
1523                 info->exc_block                = exc;
1524                 info->exc_idx                  = idx[0];
1525
1526                 for (i = 0; i < n; ++i) {
1527                         set_Block_cfgpred(exc, idx[i], projX);
1528                 }
1529
1530                 if (n > 1) {
1531                         /* the exception block should be optimized as some inputs are identical now */
1532                 }
1533
1534                 res |= CF_CHANGED;
1535         }
1536
1537         /* sixth step: replace old Phi */
1538         exchange(phi, projM);
1539
1540         return res | DF_CHANGED;
1541 }  /* optimize_phi */
1542
1543 /**
1544  * walker, do the optimizations
1545  */
1546 static void do_load_store_optimize(ir_node *n, void *env) {
1547         walk_env_t *wenv = env;
1548
1549         switch (get_irn_opcode(n)) {
1550
1551         case iro_Load:
1552                 wenv->changes |= optimize_load(n);
1553                 break;
1554
1555         case iro_Store:
1556                 wenv->changes |= optimize_store(n);
1557                 break;
1558
1559         case iro_Phi:
1560                 wenv->changes |= optimize_phi(n, wenv);
1561                 break;
1562
1563         default:
1564                 ;
1565         }
1566 }  /* do_load_store_optimize */
1567
1568 /** A scc. */
1569 typedef struct scc {
1570         ir_node *head;          /**< the head of the list */
1571 } scc;
1572
1573 /** A node entry. */
1574 typedef struct node_entry {
1575         unsigned DFSnum;    /**< the DFS number of this node */
1576         unsigned low;       /**< the low number of this node */
1577         ir_node  *header;   /**< the header of this node */
1578         int      in_stack;  /**< flag, set if the node is on the stack */
1579         ir_node  *next;     /**< link to the next node the the same scc */
1580         scc      *pscc;     /**< the scc of this node */
1581         unsigned POnum;     /**< the post order number for blocks */
1582 } node_entry;
1583
1584 /** A loop entry. */
1585 typedef struct loop_env {
1586         ir_phase ph;           /**< the phase object */
1587         ir_node  **stack;      /**< the node stack */
1588         int      tos;          /**< tos index */
1589         unsigned nextDFSnum;   /**< the current DFS number */
1590         unsigned POnum;        /**< current post order number */
1591
1592         unsigned changes;      /**< a bitmask of graph changes */
1593 } loop_env;
1594
1595 /**
1596 * Gets the node_entry of a node
1597 */
1598 static node_entry *get_irn_ne(ir_node *irn, loop_env *env) {
1599         ir_phase   *ph = &env->ph;
1600         node_entry *e  = phase_get_irn_data(&env->ph, irn);
1601
1602         if (! e) {
1603                 e = phase_alloc(ph, sizeof(*e));
1604                 memset(e, 0, sizeof(*e));
1605                 phase_set_irn_data(ph, irn, e);
1606         }
1607         return e;
1608 }  /* get_irn_ne */
1609
1610 /**
1611  * Push a node onto the stack.
1612  *
1613  * @param env   the loop environment
1614  * @param n     the node to push
1615  */
1616 static void push(loop_env *env, ir_node *n) {
1617         node_entry *e;
1618
1619         if (env->tos == ARR_LEN(env->stack)) {
1620                 int nlen = ARR_LEN(env->stack) * 2;
1621                 ARR_RESIZE(ir_node *, env->stack, nlen);
1622         }
1623         env->stack[env->tos++] = n;
1624         e = get_irn_ne(n, env);
1625         e->in_stack = 1;
1626 }  /* push */
1627
1628 /**
1629  * pop a node from the stack
1630  *
1631  * @param env   the loop environment
1632  *
1633  * @return  The topmost node
1634  */
1635 static ir_node *pop(loop_env *env) {
1636         ir_node *n = env->stack[--env->tos];
1637         node_entry *e = get_irn_ne(n, env);
1638
1639         e->in_stack = 0;
1640         return n;
1641 }  /* pop */
1642
1643 /**
1644  * Check if irn is a region constant.
1645  * The block or irn must strictly dominate the header block.
1646  *
1647  * @param irn           the node to check
1648  * @param header_block  the header block of the induction variable
1649  */
1650 static int is_rc(ir_node *irn, ir_node *header_block) {
1651         ir_node *block = get_nodes_block(irn);
1652
1653         return (block != header_block) && block_dominates(block, header_block);
1654 }  /* is_rc */
1655
1656 typedef struct phi_entry phi_entry;
1657 struct phi_entry {
1658         ir_node   *phi;    /**< A phi with a region const memory. */
1659         int       pos;     /**< The position of the region const memory */
1660         ir_node   *load;   /**< the newly created load for this phi */
1661         phi_entry *next;
1662 };
1663
1664 /**
1665  * Move loops out of loops if possible.
1666  *
1667  * @param pscc   the loop described by an SCC
1668  * @param env    the loop environment
1669  */
1670 static void move_loads_out_of_loops(scc *pscc, loop_env *env) {
1671         ir_node   *phi, *load, *next, *other, *next_other;
1672         ir_entity *ent;
1673         int       j;
1674         phi_entry *phi_list = NULL;
1675
1676         /* collect all outer memories */
1677         for (phi = pscc->head; phi != NULL; phi = next) {
1678                 node_entry *ne = get_irn_ne(phi, env);
1679                 next = ne->next;
1680
1681                 /* check all memory Phi's */
1682                 if (! is_Phi(phi))
1683                         continue;
1684
1685                 assert(get_irn_mode(phi) == mode_M && "DFS geturn non-memory Phi");
1686
1687                 for (j = get_irn_arity(phi) - 1; j >= 0; --j) {
1688                         ir_node    *pred = get_irn_n(phi, j);
1689                         node_entry *pe   = get_irn_ne(pred, env);
1690
1691                         if (pe->pscc != ne->pscc) {
1692                                 /* not in the same SCC, is region const */
1693                                 phi_entry *pe = phase_alloc(&env->ph, sizeof(*pe));
1694
1695                                 pe->phi  = phi;
1696                                 pe->pos  = j;
1697                                 pe->next = phi_list;
1698                                 phi_list = pe;
1699                         }
1700                 }
1701         }
1702         /* no Phis no fun */
1703         assert(phi_list != NULL && "DFS found a loop without Phi");
1704
1705         for (load = pscc->head; load; load = next) {
1706                 ir_mode *load_mode;
1707                 node_entry *ne = get_irn_ne(load, env);
1708                 next = ne->next;
1709
1710                 if (is_Load(load)) {
1711                         ldst_info_t *info = get_irn_link(load);
1712                         ir_node     *ptr = get_Load_ptr(load);
1713
1714                         /* for now, we cannot handle Loads with exceptions */
1715                         if (info->projs[pn_Load_res] == NULL || info->projs[pn_Load_X_regular] != NULL || info->projs[pn_Load_X_except] != NULL)
1716                                 continue;
1717
1718                         /* for now, we can only handle Load(Global) */
1719                         if (! is_Global(ptr))
1720                                 continue;
1721                         ent = get_Global_entity(ptr);
1722                         load_mode = get_Load_mode(load);
1723                         for (other = pscc->head; other != NULL; other = next_other) {
1724                                 node_entry *ne = get_irn_ne(other, env);
1725                                 next_other = ne->next;
1726
1727                                 if (is_Store(other)) {
1728                                         ir_alias_relation rel = get_alias_relation(
1729                                                 current_ir_graph,
1730                                                 get_Store_ptr(other),
1731                                                 get_irn_mode(get_Store_value(other)),
1732                                                 ptr, load_mode);
1733                                         /* if the might be an alias, we cannot pass this Store */
1734                                         if (rel != ir_no_alias)
1735                                                 break;
1736                                 }
1737                                 /* only pure Calls are allowed here, so ignore them */
1738                         }
1739                         if (other == NULL) {
1740                                 ldst_info_t *ninfo;
1741                                 phi_entry   *pe;
1742                                 dbg_info    *db;
1743
1744                                 /* for now, we cannot handle more than one input */
1745                                 if (phi_list->next != NULL)
1746                                         return;
1747
1748                                 /* yep, no aliasing Store found, Load can be moved */
1749                                 DB((dbg, LEVEL_1, "  Found a Load that could be moved: %+F\n", load));
1750
1751                                 db   = get_irn_dbg_info(load);
1752                                 for (pe = phi_list; pe != NULL; pe = pe->next) {
1753                                         int     pos   = pe->pos;
1754                                         ir_node *phi  = pe->phi;
1755                                         ir_node *blk  = get_nodes_block(phi);
1756                                         ir_node *pred = get_Block_cfgpred_block(blk, pos);
1757                                         ir_node *irn, *mem;
1758
1759                                         pe->load = irn = new_rd_Load(db, current_ir_graph, pred, get_Phi_pred(phi, pos), ptr, load_mode);
1760                                         ninfo = get_ldst_info(irn, phase_obst(&env->ph));
1761
1762                                         ninfo->projs[pn_Load_M] = mem = new_r_Proj(current_ir_graph, pred, irn, mode_M, pn_Load_M);
1763                                         set_Phi_pred(phi, pos, mem);
1764
1765                                         ninfo->projs[pn_Load_res] = new_r_Proj(current_ir_graph, pred, irn, load_mode, pn_Load_res);
1766
1767                                         DB((dbg, LEVEL_1, "  Created %+F in %+F\n", irn, pred));
1768                                 }
1769
1770                                 /* now kill the old Load */
1771                                 exchange(info->projs[pn_Load_M], get_Load_mem(load));
1772                                 exchange(info->projs[pn_Load_res], ninfo->projs[pn_Load_res]);
1773
1774                                 env->changes |= DF_CHANGED;
1775                         }
1776                 }
1777         }
1778 }  /* move_loads_out_of_loops */
1779
1780 /**
1781  * Process a loop SCC.
1782  *
1783  * @param pscc  the SCC
1784  * @param env   the loop environment
1785  */
1786 static void process_loop(scc *pscc, loop_env *env) {
1787         ir_node *irn, *next, *header = NULL;
1788         node_entry *b, *h = NULL;
1789         int j, only_phi, num_outside, process = 0;
1790         ir_node *out_rc;
1791
1792         /* find the header block for this scc */
1793         for (irn = pscc->head; irn; irn = next) {
1794                 node_entry *e = get_irn_ne(irn, env);
1795                 ir_node *block = get_nodes_block(irn);
1796
1797                 next = e->next;
1798                 b = get_irn_ne(block, env);
1799
1800                 if (header) {
1801                         if (h->POnum < b->POnum) {
1802                                 header = block;
1803                                 h      = b;
1804                         }
1805                 }
1806                 else {
1807                         header = block;
1808                         h      = b;
1809                 }
1810         }
1811
1812         /* check if this scc contains only Phi, Loads or Stores nodes */
1813         only_phi    = 1;
1814         num_outside = 0;
1815         out_rc      = NULL;
1816         for (irn = pscc->head; irn; irn = next) {
1817                 node_entry *e = get_irn_ne(irn, env);
1818
1819                 next = e->next;
1820                 switch (get_irn_opcode(irn)) {
1821                 case iro_Call:
1822                         if (is_Call_pure(irn)) {
1823                                 /* pure calls can be treated like loads */
1824                                 only_phi = 0;
1825                                 break;
1826                         }
1827                         /* non-pure calls must be handle like may-alias Stores */
1828                         goto fail;
1829                 case iro_CopyB:
1830                         /* cannot handle CopyB yet */
1831                         goto fail;
1832                 case iro_Load:
1833                         process = 1;
1834                         if (get_Load_volatility(irn) == volatility_is_volatile) {
1835                                 /* cannot handle loops with volatile Loads */
1836                                 goto fail;
1837                         }
1838                         only_phi = 0;
1839                         break;
1840                 case iro_Store:
1841                         if (get_Store_volatility(irn) == volatility_is_volatile) {
1842                                 /* cannot handle loops with volatile Stores */
1843                                 goto fail;
1844                         }
1845                         only_phi = 0;
1846                         break;
1847                 default:
1848                         only_phi = 0;
1849                         break;
1850                 case iro_Phi:
1851                         for (j = get_irn_arity(irn) - 1; j >= 0; --j) {
1852                                 ir_node *pred  = get_irn_n(irn, j);
1853                                 node_entry *pe = get_irn_ne(pred, env);
1854
1855                                 if (pe->pscc != e->pscc) {
1856                                         /* not in the same SCC, must be a region const */
1857                                         if (! is_rc(pred, header)) {
1858                                                 /* not a memory loop */
1859                                                 goto fail;
1860                                         }
1861                                         if (! out_rc) {
1862                                                 out_rc = pred;
1863                                                 ++num_outside;
1864                                         } else if (out_rc != pred) {
1865                                                 ++num_outside;
1866                                         }
1867                                 }
1868                         }
1869                         break;
1870                 }
1871         }
1872         if (! process)
1873                 goto fail;
1874
1875         /* found a memory loop */
1876         DB((dbg, LEVEL_2, "  Found a memory loop:\n  "));
1877         if (only_phi && num_outside == 1) {
1878                 /* a phi cycle with only one real predecessor can be collapsed */
1879                 DB((dbg, LEVEL_2, "  Found an USELESS Phi cycle:\n  "));
1880
1881                 for (irn = pscc->head; irn; irn = next) {
1882                         node_entry *e = get_irn_ne(irn, env);
1883                         next = e->next;
1884                         e->header = NULL;
1885                         exchange(irn, out_rc);
1886                 }
1887                 env->changes |= DF_CHANGED;
1888                 return;
1889         }
1890
1891         /* set the header for every node in this scc */
1892         for (irn = pscc->head; irn; irn = next) {
1893                 node_entry *e = get_irn_ne(irn, env);
1894                 e->header = header;
1895                 next = e->next;
1896                 DB((dbg, LEVEL_2, " %+F,", irn));
1897         }
1898         DB((dbg, LEVEL_2, "\n"));
1899
1900         move_loads_out_of_loops(pscc, env);
1901
1902 fail:
1903         ;
1904 }  /* process_loop */
1905
1906 /**
1907  * Process a SCC.
1908  *
1909  * @param pscc  the SCC
1910  * @param env   the loop environment
1911  */
1912 static void process_scc(scc *pscc, loop_env *env) {
1913         ir_node *head = pscc->head;
1914         node_entry *e = get_irn_ne(head, env);
1915
1916 #ifdef DEBUG_libfirm
1917         {
1918                 ir_node *irn, *next;
1919
1920                 DB((dbg, LEVEL_4, " SCC at %p:\n ", pscc));
1921                 for (irn = pscc->head; irn; irn = next) {
1922                         node_entry *e = get_irn_ne(irn, env);
1923
1924                         next = e->next;
1925
1926                         DB((dbg, LEVEL_4, " %+F,", irn));
1927                 }
1928                 DB((dbg, LEVEL_4, "\n"));
1929         }
1930 #endif
1931
1932         if (e->next != NULL) {
1933                 /* this SCC has more than one member */
1934                 process_loop(pscc, env);
1935         }
1936 }  /* process_scc */
1937
1938 /**
1939  * Do Tarjan's SCC algorithm and drive load/store optimization.
1940  *
1941  * @param irn  start at this node
1942  * @param env  the loop environment
1943  */
1944 static void dfs(ir_node *irn, loop_env *env)
1945 {
1946         int i, n;
1947         node_entry *node = get_irn_ne(irn, env);
1948
1949         mark_irn_visited(irn);
1950
1951         node->DFSnum = env->nextDFSnum++;
1952         node->low    = node->DFSnum;
1953         push(env, irn);
1954
1955         /* handle preds */
1956         if (is_Phi(irn) || is_Sync(irn)) {
1957                 n = get_irn_arity(irn);
1958                 for (i = 0; i < n; ++i) {
1959                         ir_node *pred = get_irn_n(irn, i);
1960                         node_entry *o = get_irn_ne(pred, env);
1961
1962                         if (irn_not_visited(pred)) {
1963                                 dfs(pred, env);
1964                                 node->low = MIN(node->low, o->low);
1965                         }
1966                         if (o->DFSnum < node->DFSnum && o->in_stack)
1967                                 node->low = MIN(o->DFSnum, node->low);
1968                 }
1969         } else if (is_fragile_op(irn)) {
1970                 ir_node *pred = get_fragile_op_mem(irn);
1971                 node_entry *o = get_irn_ne(pred, env);
1972
1973                 if (irn_not_visited(pred)) {
1974                         dfs(pred, env);
1975                         node->low = MIN(node->low, o->low);
1976                 }
1977                 if (o->DFSnum < node->DFSnum && o->in_stack)
1978                         node->low = MIN(o->DFSnum, node->low);
1979         } else if (is_Proj(irn)) {
1980                 ir_node *pred = get_Proj_pred(irn);
1981                 node_entry *o = get_irn_ne(pred, env);
1982
1983                 if (irn_not_visited(pred)) {
1984                         dfs(pred, env);
1985                         node->low = MIN(node->low, o->low);
1986                 }
1987                 if (o->DFSnum < node->DFSnum && o->in_stack)
1988                         node->low = MIN(o->DFSnum, node->low);
1989         }
1990         else {
1991                  /* IGNORE predecessors */
1992         }
1993
1994         if (node->low == node->DFSnum) {
1995                 scc *pscc = phase_alloc(&env->ph, sizeof(*pscc));
1996                 ir_node *x;
1997
1998                 pscc->head = NULL;
1999                 do {
2000                         node_entry *e;
2001
2002                         x = pop(env);
2003                         e = get_irn_ne(x, env);
2004                         e->pscc    = pscc;
2005                         e->next    = pscc->head;
2006                         pscc->head = x;
2007                 } while (x != irn);
2008
2009                 process_scc(pscc, env);
2010         }
2011 }  /* dfs */
2012
2013 /**
2014  * Do the DFS on the memory edges a graph.
2015  *
2016  * @param irg  the graph to process
2017  * @param env  the loop environment
2018  */
2019 static void do_dfs(ir_graph *irg, loop_env *env) {
2020         ir_graph *rem = current_ir_graph;
2021         ir_node  *endblk, *end;
2022         int      i;
2023
2024         current_ir_graph = irg;
2025         inc_irg_visited(irg);
2026
2027         /* visit all memory nodes */
2028         endblk = get_irg_end_block(irg);
2029         for (i = get_Block_n_cfgpreds(endblk) - 1; i >= 0; --i) {
2030                 ir_node *pred = get_Block_cfgpred(endblk, i);
2031
2032                 pred = skip_Proj(pred);
2033                 if (is_Return(pred))
2034                         dfs(get_Return_mem(pred), env);
2035                 else if (is_Raise(pred))
2036                         dfs(get_Raise_mem(pred), env);
2037                 else if (is_fragile_op(pred))
2038                         dfs(get_fragile_op_mem(pred), env);
2039                 else {
2040                         assert(0 && "Unknown EndBlock predecessor");
2041                 }
2042         }
2043
2044         /* visit the keep-alives */
2045         end = get_irg_end(irg);
2046         for (i = get_End_n_keepalives(end) - 1; i >= 0; --i) {
2047                 ir_node *ka = get_End_keepalive(end, i);
2048
2049                 if (is_Phi(ka) && irn_not_visited(ka))
2050                         dfs(ka, env);
2051         }
2052         current_ir_graph = rem;
2053 }  /* do_dfs */
2054
2055 /**
2056  * Initialize new phase data. We do this always explicit, so return NULL here
2057  */
2058 static void *init_loop_data(ir_phase *ph, const ir_node *irn, void *data) {
2059         (void)ph;
2060         (void)irn;
2061         (void)data;
2062         return NULL;
2063 }  /* init_loop_data */
2064
2065 /**
2066  * Optimize Loads/Stores in loops.
2067  *
2068  * @param irg  the graph
2069  */
2070 static int optimize_loops(ir_graph *irg) {
2071         loop_env env;
2072
2073         env.stack         = NEW_ARR_F(ir_node *, 128);
2074         env.tos           = 0;
2075         env.nextDFSnum    = 0;
2076         env.POnum         = 0;
2077         env.changes       = 0;
2078         phase_init(&env.ph, "ldstopt", irg, PHASE_DEFAULT_GROWTH, init_loop_data, NULL);
2079
2080         /* calculate the SCC's and drive loop optimization. */
2081         do_dfs(irg, &env);
2082
2083         DEL_ARR_F(env.stack);
2084         phase_free(&env.ph);
2085
2086         return env.changes;
2087 }  /* optimize_loops */
2088
2089 /*
2090  * do the load store optimization
2091  */
2092 void optimize_load_store(ir_graph *irg) {
2093         walk_env_t env;
2094
2095         FIRM_DBG_REGISTER(dbg, "firm.opt.ldstopt");
2096
2097         assert(get_irg_phase_state(irg) != phase_building);
2098         assert(get_irg_pinned(irg) != op_pin_state_floats &&
2099                 "LoadStore optimization needs pinned graph");
2100
2101         /* we need landing pads */
2102         remove_critical_cf_edges(irg);
2103
2104         edges_assure(irg);
2105
2106         /* for Phi optimization post-dominators are needed ... */
2107         assure_postdoms(irg);
2108
2109         if (get_opt_alias_analysis()) {
2110                 assure_irg_address_taken_computed(irg);
2111                 assure_irp_globals_address_taken_computed();
2112         }
2113
2114         obstack_init(&env.obst);
2115         env.changes = 0;
2116
2117         /* init the links, then collect Loads/Stores/Proj's in lists */
2118         master_visited = 0;
2119         irg_walk_graph(irg, firm_clear_link, collect_nodes, &env);
2120
2121         /* now we have collected enough information, optimize */
2122         irg_walk_graph(irg, NULL, do_load_store_optimize, &env);
2123
2124         env.changes |= optimize_loops(irg);
2125
2126         obstack_free(&env.obst, NULL);
2127
2128         /* Handle graph state */
2129         if (env.changes) {
2130                 set_irg_outs_inconsistent(irg);
2131         }
2132
2133         if (env.changes & CF_CHANGED) {
2134                 /* is this really needed: Yes, control flow changed, block might
2135                 have Bad() predecessors. */
2136                 set_irg_doms_inconsistent(irg);
2137         }
2138 }  /* optimize_load_store */