1 /*
   2  * Copyright 2007 Sun Microsystems, Inc.  All Rights Reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
  20  * CA 95054 USA or visit www.sun.com if you need additional information or
  21  * have any questions.
  22  */
  23 
  24 #include "incls/_precompiled.incl"
  25 #include "incls/_superword.cpp.incl"
  26 
  27 //
  28 //                  S U P E R W O R D   T R A N S F O R M
  29 //=============================================================================
  30 
  31 //------------------------------SuperWord---------------------------
  32 SuperWord::SuperWord(PhaseIdealLoop* phase) :
  33   _phase(phase),
  34   _igvn(phase->_igvn),
  35   _arena(phase->C->comp_arena()),
  36   _packset(arena(), 8,  0, NULL),         // packs for the current block
  37   _bb_idx(arena(), (int)(1.10 * phase->C->unique()), 0, 0), // node idx to index in bb
  38   _block(arena(), 8,  0, NULL),           // nodes in current block
  39   _data_entry(arena(), 8,  0, NULL),      // nodes with all inputs from outside
  40   _mem_slice_head(arena(), 8,  0, NULL),  // memory slice heads
  41   _mem_slice_tail(arena(), 8,  0, NULL),  // memory slice tails
  42   _node_info(arena(), 8,  0, SWNodeInfo::initial), // info needed per node
  43   _align_to_ref(NULL),                    // memory reference to align vectors to
  44   _disjoint_ptrs(arena(), 8,  0, OrderedPair::initial), // runtime disambiguated pointer pairs
  45   _dg(_arena),                            // dependence graph
  46   _visited(arena()),                      // visited node set
  47   _post_visited(arena()),                 // post visited node set
  48   _n_idx_list(arena(), 8),                // scratch list of (node,index) pairs
  49   _stk(arena(), 8, 0, NULL),              // scratch stack of nodes
  50   _nlist(arena(), 8, 0, NULL),            // scratch list of nodes
  51   _lpt(NULL),                             // loop tree node
  52   _lp(NULL),                              // LoopNode
  53   _bb(NULL),                              // basic block
  54   _iv(NULL)                               // induction var
  55 {}
  56 
  57 //------------------------------transform_loop---------------------------
  58 void SuperWord::transform_loop(IdealLoopTree* lpt) {
  59   assert(lpt->_head->is_CountedLoop(), "must be");
  60   CountedLoopNode *cl = lpt->_head->as_CountedLoop();
  61 
  62   if (!cl->is_main_loop() ) return; // skip normal, pre, and post loops
  63 
  64   // Check for no control flow in body (other than exit)
  65   Node *cl_exit = cl->loopexit();
  66   if (cl_exit->in(0) != lpt->_head) return;
  67 
  68   // Check for pre-loop ending with CountedLoopEnd(Bool(Cmp(x,Opaque1(limit))))
  69   CountedLoopEndNode* pre_end = get_pre_loop_end(cl);
  70   if (pre_end == NULL) return;
  71   Node *pre_opaq1 = pre_end->limit();
  72   if (pre_opaq1->Opcode() != Op_Opaque1) return;
  73 
  74   // Do vectors exist on this architecture?
  75   if (vector_width_in_bytes() == 0) return;
  76 
  77   init(); // initialize data structures
  78 
  79   set_lpt(lpt);
  80   set_lp(cl);
  81 
  82  // For now, define one block which is the entire loop body
  83   set_bb(cl);
  84 
  85   assert(_packset.length() == 0, "packset must be empty");
  86   SLP_extract();
  87 }
  88 
  89 //------------------------------SLP_extract---------------------------
  90 // Extract the superword level parallelism
  91 //
  92 // 1) A reverse post-order of nodes in the block is constructed.  By scanning
  93 //    this list from first to last, all definitions are visited before their uses.
  94 //
  95 // 2) A point-to-point dependence graph is constructed between memory references.
  96 //    This simplies the upcoming "independence" checker.
  97 //
  98 // 3) The maximum depth in the node graph from the beginning of the block
  99 //    to each node is computed.  This is used to prune the graph search
 100 //    in the independence checker.
 101 //
 102 // 4) For integer types, the necessary bit width is propagated backwards
 103 //    from stores to allow packed operations on byte, char, and short
 104 //    integers.  This reverses the promotion to type "int" that javac
 105 //    did for operations like: char c1,c2,c3;  c1 = c2 + c3.
 106 //
 107 // 5) One of the memory references is picked to be an aligned vector reference.
 108 //    The pre-loop trip count is adjusted to align this reference in the
 109 //    unrolled body.
 110 //
 111 // 6) The initial set of pack pairs is seeded with memory references.
 112 //
 113 // 7) The set of pack pairs is extended by following use->def and def->use links.
 114 //
 115 // 8) The pairs are combined into vector sized packs.
 116 //
 117 // 9) Reorder the memory slices to co-locate members of the memory packs.
 118 //
 119 // 10) Generate ideal vector nodes for the final set of packs and where necessary,
 120 //    inserting scalar promotion, vector creation from multiple scalars, and
 121 //    extraction of scalar values from vectors.
 122 //
 123 void SuperWord::SLP_extract() {
 124 
 125   // Ready the block
 126 
 127   construct_bb();
 128 
 129   dependence_graph();
 130 
 131   compute_max_depth();
 132 
 133   compute_vector_element_type();
 134 
 135   // Attempt vectorization
 136 
 137   find_adjacent_refs();
 138 
 139   extend_packlist();
 140 
 141   combine_packs();
 142 
 143   construct_my_pack_map();
 144 
 145   filter_packs();
 146 
 147   schedule();
 148 
 149   output();
 150 }
 151 
 152 //------------------------------find_adjacent_refs---------------------------
 153 // Find the adjacent memory references and create pack pairs for them.
 154 // This is the initial set of packs that will then be extended by
 155 // following use->def and def->use links.  The align positions are
 156 // assigned relative to the reference "align_to_ref"
 157 void SuperWord::find_adjacent_refs() {
 158   // Get list of memory operations
 159   Node_List memops;
 160   for (int i = 0; i < _block.length(); i++) {
 161     Node* n = _block.at(i);
 162     if (n->is_Mem() && in_bb(n) &&
 163         is_java_primitive(n->as_Mem()->memory_type())) {
 164       int align = memory_alignment(n->as_Mem(), 0);
 165       if (align != bottom_align) {
 166         memops.push(n);
 167       }
 168     }
 169   }
 170   if (memops.size() == 0) return;
 171 
 172   // Find a memory reference to align to.  The pre-loop trip count
 173   // is modified to align this reference to a vector-aligned address
 174   find_align_to_ref(memops);
 175   if (align_to_ref() == NULL) return;
 176 
 177   SWPointer align_to_ref_p(align_to_ref(), this);
 178   int offset = align_to_ref_p.offset_in_bytes();
 179   int scale  = align_to_ref_p.scale_in_bytes();
 180   int vw              = vector_width_in_bytes();
 181   int stride_sign     = (scale * iv_stride()) > 0 ? 1 : -1;
 182   int iv_adjustment   = (stride_sign * vw - (offset % vw)) % vw;
 183 
 184 #ifndef PRODUCT
 185   if (TraceSuperWord)
 186     tty->print_cr("\noffset = %d iv_adjustment = %d  elt_align = %d scale = %d iv_stride = %d",
 187                   offset, iv_adjustment, align_to_ref_p.memory_size(), align_to_ref_p.scale_in_bytes(), iv_stride());
 188 #endif
 189 
 190   // Set alignment relative to "align_to_ref"
 191   for (int i = memops.size() - 1; i >= 0; i--) {
 192     MemNode* s = memops.at(i)->as_Mem();
 193     SWPointer p2(s, this);
 194     if (p2.comparable(align_to_ref_p)) {
 195       int align = memory_alignment(s, iv_adjustment);
 196       set_alignment(s, align);
 197     } else {
 198       memops.remove(i);
 199     }
 200   }
 201 
 202   // Create initial pack pairs of memory operations
 203   for (uint i = 0; i < memops.size(); i++) {
 204     Node* s1 = memops.at(i);
 205     for (uint j = 0; j < memops.size(); j++) {
 206       Node* s2 = memops.at(j);
 207       if (s1 != s2 && are_adjacent_refs(s1, s2)) {
 208         int align = alignment(s1);
 209         if (stmts_can_pack(s1, s2, align)) {
 210           Node_List* pair = new Node_List();
 211           pair->push(s1);
 212           pair->push(s2);
 213           _packset.append(pair);
 214         }
 215       }
 216     }
 217   }
 218 
 219 #ifndef PRODUCT
 220   if (TraceSuperWord) {
 221     tty->print_cr("\nAfter find_adjacent_refs");
 222     print_packset();
 223   }
 224 #endif
 225 }
 226 
 227 //------------------------------find_align_to_ref---------------------------
 228 // Find a memory reference to align the loop induction variable to.
 229 // Looks first at stores then at loads, looking for a memory reference
 230 // with the largest number of references similar to it.
 231 void SuperWord::find_align_to_ref(Node_List &memops) {
 232   GrowableArray<int> cmp_ct(arena(), memops.size(), memops.size(), 0);
 233 
 234   // Count number of comparable memory ops
 235   for (uint i = 0; i < memops.size(); i++) {
 236     MemNode* s1 = memops.at(i)->as_Mem();
 237     SWPointer p1(s1, this);
 238     // Discard if pre loop can't align this reference
 239     if (!ref_is_alignable(p1)) {
 240       *cmp_ct.adr_at(i) = 0;
 241       continue;
 242     }
 243     for (uint j = i+1; j < memops.size(); j++) {
 244       MemNode* s2 = memops.at(j)->as_Mem();
 245       if (isomorphic(s1, s2)) {
 246         SWPointer p2(s2, this);
 247         if (p1.comparable(p2)) {
 248           (*cmp_ct.adr_at(i))++;
 249           (*cmp_ct.adr_at(j))++;
 250         }
 251       }
 252     }
 253   }
 254 
 255   // Find Store (or Load) with the greatest number of "comparable" references
 256   int max_ct        = 0;
 257   int max_idx       = -1;
 258   int min_size      = max_jint;
 259   int min_iv_offset = max_jint;
 260   for (uint j = 0; j < memops.size(); j++) {
 261     MemNode* s = memops.at(j)->as_Mem();
 262     if (s->is_Store()) {
 263       SWPointer p(s, this);
 264       if (cmp_ct.at(j) > max_ct ||
 265           cmp_ct.at(j) == max_ct && (data_size(s) < min_size ||
 266                                      data_size(s) == min_size &&
 267                                         p.offset_in_bytes() < min_iv_offset)) {
 268         max_ct = cmp_ct.at(j);
 269         max_idx = j;
 270         min_size = data_size(s);
 271         min_iv_offset = p.offset_in_bytes();
 272       }
 273     }
 274   }
 275   // If no stores, look at loads
 276   if (max_ct == 0) {
 277     for (uint j = 0; j < memops.size(); j++) {
 278       MemNode* s = memops.at(j)->as_Mem();
 279       if (s->is_Load()) {
 280         SWPointer p(s, this);
 281         if (cmp_ct.at(j) > max_ct ||
 282             cmp_ct.at(j) == max_ct && (data_size(s) < min_size ||
 283                                        data_size(s) == min_size &&
 284                                           p.offset_in_bytes() < min_iv_offset)) {
 285           max_ct = cmp_ct.at(j);
 286           max_idx = j;
 287           min_size = data_size(s);
 288           min_iv_offset = p.offset_in_bytes();
 289         }
 290       }
 291     }
 292   }
 293 
 294   if (max_ct > 0)
 295     set_align_to_ref(memops.at(max_idx)->as_Mem());
 296 
 297 #ifndef PRODUCT
 298   if (TraceSuperWord && Verbose) {
 299     tty->print_cr("\nVector memops after find_align_to_refs");
 300     for (uint i = 0; i < memops.size(); i++) {
 301       MemNode* s = memops.at(i)->as_Mem();
 302       s->dump();
 303     }
 304   }
 305 #endif
 306 }
 307 
 308 //------------------------------ref_is_alignable---------------------------
 309 // Can the preloop align the reference to position zero in the vector?
 310 bool SuperWord::ref_is_alignable(SWPointer& p) {
 311   if (!p.has_iv()) {
 312     return true;   // no induction variable
 313   }
 314   CountedLoopEndNode* pre_end = get_pre_loop_end(lp()->as_CountedLoop());
 315   assert(pre_end->stride_is_con(), "pre loop stride is constant");
 316   int preloop_stride = pre_end->stride_con();
 317 
 318   int span = preloop_stride * p.scale_in_bytes();
 319 
 320   // Stride one accesses are alignable.
 321   if (ABS(span) == p.memory_size())
 322     return true;
 323 
 324   // If initial offset from start of object is computable,
 325   // compute alignment within the vector.
 326   int vw = vector_width_in_bytes();
 327   if (vw % span == 0) {
 328     Node* init_nd = pre_end->init_trip();
 329     if (init_nd->is_Con() && p.invar() == NULL) {
 330       int init = init_nd->bottom_type()->is_int()->get_con();
 331 
 332       int init_offset = init * p.scale_in_bytes() + p.offset_in_bytes();
 333       assert(init_offset >= 0, "positive offset from object start");
 334 
 335       if (span > 0) {
 336         return (vw - (init_offset % vw)) % span == 0;
 337       } else {
 338         assert(span < 0, "nonzero stride * scale");
 339         return (init_offset % vw) % -span == 0;
 340       }
 341     }
 342   }
 343   return false;
 344 }
 345 
 346 //---------------------------dependence_graph---------------------------
 347 // Construct dependency graph.
 348 // Add dependence edges to load/store nodes for memory dependence
 349 //    A.out()->DependNode.in(1) and DependNode.out()->B.prec(x)
 350 void SuperWord::dependence_graph() {
 351   // First, assign a dependence node to each memory node
 352   for (int i = 0; i < _block.length(); i++ ) {
 353     Node *n = _block.at(i);
 354     if (n->is_Mem() || n->is_Phi() && n->bottom_type() == Type::MEMORY) {
 355       _dg.make_node(n);
 356     }
 357   }
 358 
 359   // For each memory slice, create the dependences
 360   for (int i = 0; i < _mem_slice_head.length(); i++) {
 361     Node* n      = _mem_slice_head.at(i);
 362     Node* n_tail = _mem_slice_tail.at(i);
 363 
 364     // Get slice in predecessor order (last is first)
 365     mem_slice_preds(n_tail, n, _nlist);
 366 
 367     // Make the slice dependent on the root
 368     DepMem* slice = _dg.dep(n);
 369     _dg.make_edge(_dg.root(), slice);
 370 
 371     // Create a sink for the slice
 372     DepMem* slice_sink = _dg.make_node(NULL);
 373     _dg.make_edge(slice_sink, _dg.tail());
 374 
 375     // Now visit each pair of memory ops, creating the edges
 376     for (int j = _nlist.length() - 1; j >= 0 ; j--) {
 377       Node* s1 = _nlist.at(j);
 378 
 379       // If no dependency yet, use slice
 380       if (_dg.dep(s1)->in_cnt() == 0) {
 381         _dg.make_edge(slice, s1);
 382       }
 383       SWPointer p1(s1->as_Mem(), this);
 384       bool sink_dependent = true;
 385       for (int k = j - 1; k >= 0; k--) {
 386         Node* s2 = _nlist.at(k);
 387         if (s1->is_Load() && s2->is_Load())
 388           continue;
 389         SWPointer p2(s2->as_Mem(), this);
 390 
 391         int cmp = p1.cmp(p2);
 392         if (SuperWordRTDepCheck &&
 393             p1.base() != p2.base() && p1.valid() && p2.valid()) {
 394           // Create a runtime check to disambiguate
 395           OrderedPair pp(p1.base(), p2.base());
 396           _disjoint_ptrs.append_if_missing(pp);
 397         } else if (!SWPointer::not_equal(cmp)) {
 398           // Possibly same address
 399           _dg.make_edge(s1, s2);
 400           sink_dependent = false;
 401         }
 402       }
 403       if (sink_dependent) {
 404         _dg.make_edge(s1, slice_sink);
 405       }
 406     }
 407 #ifndef PRODUCT
 408     if (TraceSuperWord) {
 409       tty->print_cr("\nDependence graph for slice: %d", n->_idx);
 410       for (int q = 0; q < _nlist.length(); q++) {
 411         _dg.print(_nlist.at(q));
 412       }
 413       tty->cr();
 414     }
 415 #endif
 416     _nlist.clear();
 417   }
 418 
 419 #ifndef PRODUCT
 420   if (TraceSuperWord) {
 421     tty->print_cr("\ndisjoint_ptrs: %s", _disjoint_ptrs.length() > 0 ? "" : "NONE");
 422     for (int r = 0; r < _disjoint_ptrs.length(); r++) {
 423       _disjoint_ptrs.at(r).print();
 424       tty->cr();
 425     }
 426     tty->cr();
 427   }
 428 #endif
 429 }
 430 
 431 //---------------------------mem_slice_preds---------------------------
 432 // Return a memory slice (node list) in predecessor order starting at "start"
 433 void SuperWord::mem_slice_preds(Node* start, Node* stop, GrowableArray<Node*> &preds) {
 434   assert(preds.length() == 0, "start empty");
 435   Node* n = start;
 436   Node* prev = NULL;
 437   while (true) {
 438     assert(in_bb(n), "must be in block");
 439     for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
 440       Node* out = n->fast_out(i);
 441       if (out->is_Load()) {
 442         if (in_bb(out)) {
 443           preds.push(out);
 444         }
 445       } else {
 446         // FIXME
 447         if (out->is_MergeMem() && !in_bb(out)) {
 448           // Either unrolling is causing a memory edge not to disappear,
 449           // or need to run igvn.optimize() again before SLP
 450         } else if (out->is_Phi() && out->bottom_type() == Type::MEMORY && !in_bb(out)) {
 451           // Ditto.  Not sure what else to check further.
 452         } else if (out->Opcode() == Op_StoreCM && out->in(4) == n) {
 453           // StoreCM has an input edge used as a precedence edge.
 454           // Maybe an issue when oop stores are vectorized.
 455         } else {
 456           assert(out == prev || prev == NULL, "no branches off of store slice");
 457         }
 458       }
 459     }
 460     if (n == stop) break;
 461     preds.push(n);
 462     prev = n;
 463     n = n->in(MemNode::Memory);
 464   }
 465 }
 466 
 467 //------------------------------stmts_can_pack---------------------------
 468 // Can s1 and s2 be in a pack with s1 immediately preceeding s2 and
 469 // s1 aligned at "align"
 470 bool SuperWord::stmts_can_pack(Node* s1, Node* s2, int align) {
 471   if (isomorphic(s1, s2)) {
 472     if (independent(s1, s2)) {
 473       if (!exists_at(s1, 0) && !exists_at(s2, 1)) {
 474         if (!s1->is_Mem() || are_adjacent_refs(s1, s2)) {
 475           int s1_align = alignment(s1);
 476           int s2_align = alignment(s2);
 477           if (s1_align == top_align || s1_align == align) {
 478             if (s2_align == top_align || s2_align == align + data_size(s1)) {
 479               return true;
 480             }
 481           }
 482         }
 483       }
 484     }
 485   }
 486   return false;
 487 }
 488 
 489 //------------------------------exists_at---------------------------
 490 // Does s exist in a pack at position pos?
 491 bool SuperWord::exists_at(Node* s, uint pos) {
 492   for (int i = 0; i < _packset.length(); i++) {
 493     Node_List* p = _packset.at(i);
 494     if (p->at(pos) == s) {
 495       return true;
 496     }
 497   }
 498   return false;
 499 }
 500 
 501 //------------------------------are_adjacent_refs---------------------------
 502 // Is s1 immediately before s2 in memory?
 503 bool SuperWord::are_adjacent_refs(Node* s1, Node* s2) {
 504   if (!s1->is_Mem() || !s2->is_Mem()) return false;
 505   if (!in_bb(s1)    || !in_bb(s2))    return false;
 506   // FIXME - co_locate_pack fails on Stores in different mem-slices, so
 507   // only pack memops that are in the same alias set until that's fixed.
 508   if (_phase->C->get_alias_index(s1->as_Mem()->adr_type()) !=
 509       _phase->C->get_alias_index(s2->as_Mem()->adr_type()))
 510     return false;
 511   SWPointer p1(s1->as_Mem(), this);
 512   SWPointer p2(s2->as_Mem(), this);
 513   if (p1.base() != p2.base() || !p1.comparable(p2)) return false;
 514   int diff = p2.offset_in_bytes() - p1.offset_in_bytes();
 515   return diff == data_size(s1);
 516 }
 517 
 518 //------------------------------isomorphic---------------------------
 519 // Are s1 and s2 similar?
 520 bool SuperWord::isomorphic(Node* s1, Node* s2) {
 521   if (s1->Opcode() != s2->Opcode()) return false;
 522   if (s1->req() != s2->req()) return false;
 523   if (s1->in(0) != s2->in(0)) return false;
 524   if (velt_type(s1) != velt_type(s2)) return false;
 525   return true;
 526 }
 527 
 528 //------------------------------independent---------------------------
 529 // Is there no data path from s1 to s2 or s2 to s1?
 530 bool SuperWord::independent(Node* s1, Node* s2) {
 531   //  assert(s1->Opcode() == s2->Opcode(), "check isomorphic first");
 532   int d1 = depth(s1);
 533   int d2 = depth(s2);
 534   if (d1 == d2) return s1 != s2;
 535   Node* deep    = d1 > d2 ? s1 : s2;
 536   Node* shallow = d1 > d2 ? s2 : s1;
 537 
 538   visited_clear();
 539 
 540   return independent_path(shallow, deep);
 541 }
 542 
 543 //------------------------------independent_path------------------------------
 544 // Helper for independent
 545 bool SuperWord::independent_path(Node* shallow, Node* deep, uint dp) {
 546   if (dp >= 1000) return false; // stop deep recursion
 547   visited_set(deep);
 548   int shal_depth = depth(shallow);
 549   assert(shal_depth <= depth(deep), "must be");
 550   for (DepPreds preds(deep, _dg); !preds.done(); preds.next()) {
 551     Node* pred = preds.current();
 552     if (in_bb(pred) && !visited_test(pred)) {
 553       if (shallow == pred) {
 554         return false;
 555       }
 556       if (shal_depth < depth(pred) && !independent_path(shallow, pred, dp+1)) {
 557         return false;
 558       }
 559     }
 560   }
 561   return true;
 562 }
 563 
 564 //------------------------------set_alignment---------------------------
 565 void SuperWord::set_alignment(Node* s1, Node* s2, int align) {
 566   set_alignment(s1, align);
 567   set_alignment(s2, align + data_size(s1));
 568 }
 569 
 570 //------------------------------data_size---------------------------
 571 int SuperWord::data_size(Node* s) {
 572   const Type* t = velt_type(s);
 573   BasicType  bt = t->array_element_basic_type();
 574   int bsize = type2aelembytes(bt);
 575   assert(bsize != 0, "valid size");
 576   return bsize;
 577 }
 578 
 579 //------------------------------extend_packlist---------------------------
 580 // Extend packset by following use->def and def->use links from pack members.
 581 void SuperWord::extend_packlist() {
 582   bool changed;
 583   do {
 584     changed = false;
 585     for (int i = 0; i < _packset.length(); i++) {
 586       Node_List* p = _packset.at(i);
 587       changed |= follow_use_defs(p);
 588       changed |= follow_def_uses(p);
 589     }
 590   } while (changed);
 591 
 592 #ifndef PRODUCT
 593   if (TraceSuperWord) {
 594     tty->print_cr("\nAfter extend_packlist");
 595     print_packset();
 596   }
 597 #endif
 598 }
 599 
 600 //------------------------------follow_use_defs---------------------------
 601 // Extend the packset by visiting operand definitions of nodes in pack p
 602 bool SuperWord::follow_use_defs(Node_List* p) {
 603   Node* s1 = p->at(0);
 604   Node* s2 = p->at(1);
 605   assert(p->size() == 2, "just checking");
 606   assert(s1->req() == s2->req(), "just checking");
 607   assert(alignment(s1) + data_size(s1) == alignment(s2), "just checking");
 608 
 609   if (s1->is_Load()) return false;
 610 
 611   int align = alignment(s1);
 612   bool changed = false;
 613   int start = s1->is_Store() ? MemNode::ValueIn   : 1;
 614   int end   = s1->is_Store() ? MemNode::ValueIn+1 : s1->req();
 615   for (int j = start; j < end; j++) {
 616     Node* t1 = s1->in(j);
 617     Node* t2 = s2->in(j);
 618     if (!in_bb(t1) || !in_bb(t2))
 619       continue;
 620     if (stmts_can_pack(t1, t2, align)) {
 621       if (est_savings(t1, t2) >= 0) {
 622         Node_List* pair = new Node_List();
 623         pair->push(t1);
 624         pair->push(t2);
 625         _packset.append(pair);
 626         set_alignment(t1, t2, align);
 627         changed = true;
 628       }
 629     }
 630   }
 631   return changed;
 632 }
 633 
 634 //------------------------------follow_def_uses---------------------------
 635 // Extend the packset by visiting uses of nodes in pack p
 636 bool SuperWord::follow_def_uses(Node_List* p) {
 637   bool changed = false;
 638   Node* s1 = p->at(0);
 639   Node* s2 = p->at(1);
 640   assert(p->size() == 2, "just checking");
 641   assert(s1->req() == s2->req(), "just checking");
 642   assert(alignment(s1) + data_size(s1) == alignment(s2), "just checking");
 643 
 644   if (s1->is_Store()) return false;
 645 
 646   int align = alignment(s1);
 647   int savings = -1;
 648   Node* u1 = NULL;
 649   Node* u2 = NULL;
 650   for (DUIterator_Fast imax, i = s1->fast_outs(imax); i < imax; i++) {
 651     Node* t1 = s1->fast_out(i);
 652     if (!in_bb(t1)) continue;
 653     for (DUIterator_Fast jmax, j = s2->fast_outs(jmax); j < jmax; j++) {
 654       Node* t2 = s2->fast_out(j);
 655       if (!in_bb(t2)) continue;
 656       if (!opnd_positions_match(s1, t1, s2, t2))
 657         continue;
 658       if (stmts_can_pack(t1, t2, align)) {
 659         int my_savings = est_savings(t1, t2);
 660         if (my_savings > savings) {
 661           savings = my_savings;
 662           u1 = t1;
 663           u2 = t2;
 664         }
 665       }
 666     }
 667   }
 668   if (savings >= 0) {
 669     Node_List* pair = new Node_List();
 670     pair->push(u1);
 671     pair->push(u2);
 672     _packset.append(pair);
 673     set_alignment(u1, u2, align);
 674     changed = true;
 675   }
 676   return changed;
 677 }
 678 
 679 //---------------------------opnd_positions_match-------------------------
 680 // Is the use of d1 in u1 at the same operand position as d2 in u2?
 681 bool SuperWord::opnd_positions_match(Node* d1, Node* u1, Node* d2, Node* u2) {
 682   uint ct = u1->req();
 683   if (ct != u2->req()) return false;
 684   uint i1 = 0;
 685   uint i2 = 0;
 686   do {
 687     for (i1++; i1 < ct; i1++) if (u1->in(i1) == d1) break;
 688     for (i2++; i2 < ct; i2++) if (u2->in(i2) == d2) break;
 689     if (i1 != i2) {
 690       return false;
 691     }
 692   } while (i1 < ct);
 693   return true;
 694 }
 695 
 696 //------------------------------est_savings---------------------------
 697 // Estimate the savings from executing s1 and s2 as a pack
 698 int SuperWord::est_savings(Node* s1, Node* s2) {
 699   int save = 2 - 1; // 2 operations per instruction in packed form
 700 
 701   // inputs
 702   for (uint i = 1; i < s1->req(); i++) {
 703     Node* x1 = s1->in(i);
 704     Node* x2 = s2->in(i);
 705     if (x1 != x2) {
 706       if (are_adjacent_refs(x1, x2)) {
 707         save += adjacent_profit(x1, x2);
 708       } else if (!in_packset(x1, x2)) {
 709         save -= pack_cost(2);
 710       } else {
 711         save += unpack_cost(2);
 712       }
 713     }
 714   }
 715 
 716   // uses of result
 717   uint ct = 0;
 718   for (DUIterator_Fast imax, i = s1->fast_outs(imax); i < imax; i++) {
 719     Node* s1_use = s1->fast_out(i);
 720     for (int j = 0; j < _packset.length(); j++) {
 721       Node_List* p = _packset.at(j);
 722       if (p->at(0) == s1_use) {
 723         for (DUIterator_Fast kmax, k = s2->fast_outs(kmax); k < kmax; k++) {
 724           Node* s2_use = s2->fast_out(k);
 725           if (p->at(p->size()-1) == s2_use) {
 726             ct++;
 727             if (are_adjacent_refs(s1_use, s2_use)) {
 728               save += adjacent_profit(s1_use, s2_use);
 729             }
 730           }
 731         }
 732       }
 733     }
 734   }
 735 
 736   if (ct < s1->outcnt()) save += unpack_cost(1);
 737   if (ct < s2->outcnt()) save += unpack_cost(1);
 738 
 739   return save;
 740 }
 741 
 742 //------------------------------costs---------------------------
 743 int SuperWord::adjacent_profit(Node* s1, Node* s2) { return 2; }
 744 int SuperWord::pack_cost(int ct)   { return ct; }
 745 int SuperWord::unpack_cost(int ct) { return ct; }
 746 
 747 //------------------------------combine_packs---------------------------
 748 // Combine packs A and B with A.last == B.first into A.first..,A.last,B.second,..B.last
 749 void SuperWord::combine_packs() {
 750   bool changed;
 751   do {
 752     changed = false;
 753     for (int i = 0; i < _packset.length(); i++) {
 754       Node_List* p1 = _packset.at(i);
 755       if (p1 == NULL) continue;
 756       for (int j = 0; j < _packset.length(); j++) {
 757         Node_List* p2 = _packset.at(j);
 758         if (p2 == NULL) continue;
 759         if (p1->at(p1->size()-1) == p2->at(0)) {
 760           for (uint k = 1; k < p2->size(); k++) {
 761             p1->push(p2->at(k));
 762           }
 763           _packset.at_put(j, NULL);
 764           changed = true;
 765         }
 766       }
 767     }
 768   } while (changed);
 769 
 770   for (int i = _packset.length() - 1; i >= 0; i--) {
 771     Node_List* p1 = _packset.at(i);
 772     if (p1 == NULL) {
 773       _packset.remove_at(i);
 774     }
 775   }
 776 
 777 #ifndef PRODUCT
 778   if (TraceSuperWord) {
 779     tty->print_cr("\nAfter combine_packs");
 780     print_packset();
 781   }
 782 #endif
 783 }
 784 
 785 //-----------------------------construct_my_pack_map--------------------------
 786 // Construct the map from nodes to packs.  Only valid after the
 787 // point where a node is only in one pack (after combine_packs).
 788 void SuperWord::construct_my_pack_map() {
 789   Node_List* rslt = NULL;
 790   for (int i = 0; i < _packset.length(); i++) {
 791     Node_List* p = _packset.at(i);
 792     for (uint j = 0; j < p->size(); j++) {
 793       Node* s = p->at(j);
 794       assert(my_pack(s) == NULL, "only in one pack");
 795       set_my_pack(s, p);
 796     }
 797   }
 798 }
 799 
 800 //------------------------------filter_packs---------------------------
 801 // Remove packs that are not implemented or not profitable.
 802 void SuperWord::filter_packs() {
 803 
 804   // Remove packs that are not implemented
 805   for (int i = _packset.length() - 1; i >= 0; i--) {
 806     Node_List* pk = _packset.at(i);
 807     bool impl = implemented(pk);
 808     if (!impl) {
 809 #ifndef PRODUCT
 810       if (TraceSuperWord && Verbose) {
 811         tty->print_cr("Unimplemented");
 812         pk->at(0)->dump();
 813       }
 814 #endif
 815       remove_pack_at(i);
 816     }
 817   }
 818 
 819   // Remove packs that are not profitable
 820   bool changed;
 821   do {
 822     changed = false;
 823     for (int i = _packset.length() - 1; i >= 0; i--) {
 824       Node_List* pk = _packset.at(i);
 825       bool prof = profitable(pk);
 826       if (!prof) {
 827 #ifndef PRODUCT
 828         if (TraceSuperWord && Verbose) {
 829           tty->print_cr("Unprofitable");
 830           pk->at(0)->dump();
 831         }
 832 #endif
 833         remove_pack_at(i);
 834         changed = true;
 835       }
 836     }
 837   } while (changed);
 838 
 839 #ifndef PRODUCT
 840   if (TraceSuperWord) {
 841     tty->print_cr("\nAfter filter_packs");
 842     print_packset();
 843     tty->cr();
 844   }
 845 #endif
 846 }
 847 
 848 //------------------------------implemented---------------------------
 849 // Can code be generated for pack p?
 850 bool SuperWord::implemented(Node_List* p) {
 851   Node* p0 = p->at(0);
 852   int vopc = VectorNode::opcode(p0->Opcode(), p->size(), velt_type(p0));
 853   return vopc > 0 && Matcher::has_match_rule(vopc);
 854 }
 855 
 856 //------------------------------profitable---------------------------
 857 // For pack p, are all operands and all uses (with in the block) vector?
 858 bool SuperWord::profitable(Node_List* p) {
 859   Node* p0 = p->at(0);
 860   uint start, end;
 861   vector_opd_range(p0, &start, &end);
 862 
 863   // Return false if some input is not vector and inside block
 864   for (uint i = start; i < end; i++) {
 865     if (!is_vector_use(p0, i)) {
 866       // For now, return false if not scalar promotion case (inputs are the same.)
 867       // Later, implement PackNode and allow differring, non-vector inputs
 868       // (maybe just the ones from outside the block.)
 869       Node* p0_def = p0->in(i);
 870       for (uint j = 1; j < p->size(); j++) {
 871         Node* use = p->at(j);
 872         Node* def = use->in(i);
 873         if (p0_def != def)
 874           return false;
 875       }
 876     }
 877   }
 878   if (!p0->is_Store()) {
 879     // For now, return false if not all uses are vector.
 880     // Later, implement ExtractNode and allow non-vector uses (maybe
 881     // just the ones outside the block.)
 882     for (uint i = 0; i < p->size(); i++) {
 883       Node* def = p->at(i);
 884       for (DUIterator_Fast jmax, j = def->fast_outs(jmax); j < jmax; j++) {
 885         Node* use = def->fast_out(j);
 886         for (uint k = 0; k < use->req(); k++) {
 887           Node* n = use->in(k);
 888           if (def == n) {
 889             if (!is_vector_use(use, k)) {
 890               return false;
 891             }
 892           }
 893         }
 894       }
 895     }
 896   }
 897   return true;
 898 }
 899 
 900 //------------------------------schedule---------------------------
 901 // Adjust the memory graph for the packed operations
 902 void SuperWord::schedule() {
 903 
 904   // Co-locate in the memory graph the members of each memory pack
 905   for (int i = 0; i < _packset.length(); i++) {
 906     co_locate_pack(_packset.at(i));
 907   }
 908 }
 909 
 910 //------------------------------co_locate_pack---------------------------
 911 // Within a pack, move stores down to the last executed store,
 912 // and move loads up to the first executed load.
 913 void SuperWord::co_locate_pack(Node_List* pk) {
 914   if (pk->at(0)->is_Store()) {
 915     // Push Stores down towards last executed pack member
 916     MemNode* first     = executed_first(pk)->as_Mem();
 917     MemNode* last      = executed_last(pk)->as_Mem();
 918     MemNode* insert_pt = last;
 919     MemNode* current   = last->in(MemNode::Memory)->as_Mem();
 920     while (true) {
 921       assert(in_bb(current), "stay in block");
 922       Node* my_mem = current->in(MemNode::Memory);
 923       if (in_pack(current, pk)) {
 924         // Forward users of my memory state to my input memory state
 925         _igvn.hash_delete(current);
 926         _igvn.hash_delete(my_mem);
 927         for (DUIterator i = current->outs(); current->has_out(i); i++) {
 928           Node* use = current->out(i);
 929           if (use->is_Mem()) {
 930             assert(use->in(MemNode::Memory) == current, "must be");
 931             _igvn.hash_delete(use);
 932             use->set_req(MemNode::Memory, my_mem);
 933             _igvn._worklist.push(use);
 934             --i; // deleted this edge; rescan position
 935           }
 936         }
 937         // put current immediately before insert_pt
 938         current->set_req(MemNode::Memory, insert_pt->in(MemNode::Memory));
 939         _igvn.hash_delete(insert_pt);
 940         insert_pt->set_req(MemNode::Memory, current);
 941         _igvn._worklist.push(insert_pt);
 942         _igvn._worklist.push(current);
 943         insert_pt = current;
 944       }
 945       if (current == first) break;
 946       current = my_mem->as_Mem();
 947     }
 948   } else if (pk->at(0)->is_Load()) {
 949     // Pull Loads up towards first executed pack member
 950     LoadNode* first = executed_first(pk)->as_Load();
 951     Node* first_mem = first->in(MemNode::Memory);
 952     _igvn.hash_delete(first_mem);
 953     // Give each load same memory state as first
 954     for (uint i = 0; i < pk->size(); i++) {
 955       LoadNode* ld = pk->at(i)->as_Load();
 956       _igvn.hash_delete(ld);
 957       ld->set_req(MemNode::Memory, first_mem);
 958       _igvn._worklist.push(ld);
 959     }
 960   }
 961 }
 962 
 963 //------------------------------output---------------------------
 964 // Convert packs into vector node operations
 965 void SuperWord::output() {
 966   if (_packset.length() == 0) return;
 967 
 968   // MUST ENSURE main loop's initial value is properly aligned:
 969   //  (iv_initial_value + min_iv_offset) % vector_width_in_bytes() == 0
 970 
 971   align_initial_loop_index(align_to_ref());
 972 
 973   // Insert extract (unpack) operations for scalar uses
 974   for (int i = 0; i < _packset.length(); i++) {
 975     insert_extracts(_packset.at(i));
 976   }
 977 
 978   for (int i = 0; i < _block.length(); i++) {
 979     Node* n = _block.at(i);
 980     Node_List* p = my_pack(n);
 981     if (p && n == executed_last(p)) {
 982       uint vlen = p->size();
 983       Node* vn = NULL;
 984       Node* low_adr = p->at(0);
 985       Node* first   = executed_first(p);
 986       if (n->is_Load()) {
 987         int   opc = n->Opcode();
 988         Node* ctl = n->in(MemNode::Control);
 989         Node* mem = first->in(MemNode::Memory);
 990         Node* adr = low_adr->in(MemNode::Address);
 991         const TypePtr* atyp = n->adr_type();
 992         vn = VectorLoadNode::make(_phase->C, opc, ctl, mem, adr, atyp, vlen);
 993 
 994       } else if (n->is_Store()) {
 995         // Promote value to be stored to vector
 996         VectorNode* val = vector_opd(p, MemNode::ValueIn);
 997 
 998         int   opc = n->Opcode();
 999         Node* ctl = n->in(MemNode::Control);
1000         Node* mem = first->in(MemNode::Memory);
1001         Node* adr = low_adr->in(MemNode::Address);
1002         const TypePtr* atyp = n->adr_type();
1003         vn = VectorStoreNode::make(_phase->C, opc, ctl, mem, adr, atyp, val, vlen);
1004 
1005       } else if (n->req() == 3) {
1006         // Promote operands to vector
1007         Node* in1 = vector_opd(p, 1);
1008         Node* in2 = vector_opd(p, 2);
1009         vn = VectorNode::make(_phase->C, n->Opcode(), in1, in2, vlen, velt_type(n));
1010 
1011       } else {
1012         ShouldNotReachHere();
1013       }
1014 
1015       _phase->_igvn.register_new_node_with_optimizer(vn);
1016       _phase->set_ctrl(vn, _phase->get_ctrl(p->at(0)));
1017       for (uint j = 0; j < p->size(); j++) {
1018         Node* pm = p->at(j);
1019         _igvn.hash_delete(pm);
1020         _igvn.subsume_node(pm, vn);
1021       }
1022       _igvn._worklist.push(vn);
1023     }
1024   }
1025 }
1026 
1027 //------------------------------vector_opd---------------------------
1028 // Create a vector operand for the nodes in pack p for operand: in(opd_idx)
1029 VectorNode* SuperWord::vector_opd(Node_List* p, int opd_idx) {
1030   Node* p0 = p->at(0);
1031   uint vlen = p->size();
1032   Node* opd = p0->in(opd_idx);
1033 
1034   bool same_opd = true;
1035   for (uint i = 1; i < vlen; i++) {
1036     Node* pi = p->at(i);
1037     Node* in = pi->in(opd_idx);
1038     if (opd != in) {
1039       same_opd = false;
1040       break;
1041     }
1042   }
1043 
1044   if (same_opd) {
1045     if (opd->is_Vector()) {
1046       return (VectorNode*)opd; // input is matching vector
1047     }
1048     // Convert scalar input to vector. Use p0's type because it's container
1049     // maybe smaller than the operand's container.
1050     const Type* opd_t = velt_type(!in_bb(opd) ? p0 : opd);
1051     const Type* p0_t  = velt_type(p0);
1052     if (p0_t->higher_equal(opd_t)) opd_t = p0_t;
1053     VectorNode* vn    = VectorNode::scalar2vector(_phase->C, opd, vlen, opd_t);
1054 
1055     _phase->_igvn.register_new_node_with_optimizer(vn);
1056     _phase->set_ctrl(vn, _phase->get_ctrl(opd));
1057     return vn;
1058   }
1059 
1060   // Insert pack operation
1061   const Type* opd_t = velt_type(!in_bb(opd) ? p0 : opd);
1062   PackNode* pk = PackNode::make(_phase->C, opd, opd_t);
1063 
1064   for (uint i = 1; i < vlen; i++) {
1065     Node* pi = p->at(i);
1066     Node* in = pi->in(opd_idx);
1067     assert(my_pack(in) == NULL, "Should already have been unpacked");
1068     assert(opd_t == velt_type(!in_bb(in) ? pi : in), "all same type");
1069     pk->add_opd(in);
1070   }
1071   _phase->_igvn.register_new_node_with_optimizer(pk);
1072   _phase->set_ctrl(pk, _phase->get_ctrl(opd));
1073   return pk;
1074 }
1075 
1076 //------------------------------insert_extracts---------------------------
1077 // If a use of pack p is not a vector use, then replace the
1078 // use with an extract operation.
1079 void SuperWord::insert_extracts(Node_List* p) {
1080   if (p->at(0)->is_Store()) return;
1081   assert(_n_idx_list.is_empty(), "empty (node,index) list");
1082 
1083   // Inspect each use of each pack member.  For each use that is
1084   // not a vector use, replace the use with an extract operation.
1085 
1086   for (uint i = 0; i < p->size(); i++) {
1087     Node* def = p->at(i);
1088     for (DUIterator_Fast jmax, j = def->fast_outs(jmax); j < jmax; j++) {
1089       Node* use = def->fast_out(j);
1090       for (uint k = 0; k < use->req(); k++) {
1091         Node* n = use->in(k);
1092         if (def == n) {
1093           if (!is_vector_use(use, k)) {
1094             _n_idx_list.push(use, k);
1095           }
1096         }
1097       }
1098     }
1099   }
1100 
1101   while (_n_idx_list.is_nonempty()) {
1102     Node* use = _n_idx_list.node();
1103     int   idx = _n_idx_list.index();
1104     _n_idx_list.pop();
1105     Node* def = use->in(idx);
1106 
1107     // Insert extract operation
1108     _igvn.hash_delete(def);
1109     _igvn.hash_delete(use);
1110     int def_pos = alignment(def) / data_size(def);
1111     const Type* def_t = velt_type(def);
1112 
1113     Node* ex = ExtractNode::make(_phase->C, def, def_pos, def_t);
1114     _phase->_igvn.register_new_node_with_optimizer(ex);
1115     _phase->set_ctrl(ex, _phase->get_ctrl(def));
1116     use->set_req(idx, ex);
1117     _igvn._worklist.push(def);
1118     _igvn._worklist.push(use);
1119 
1120     bb_insert_after(ex, bb_idx(def));
1121     set_velt_type(ex, def_t);
1122   }
1123 }
1124 
1125 //------------------------------is_vector_use---------------------------
1126 // Is use->in(u_idx) a vector use?
1127 bool SuperWord::is_vector_use(Node* use, int u_idx) {
1128   Node_List* u_pk = my_pack(use);
1129   if (u_pk == NULL) return false;
1130   Node* def = use->in(u_idx);
1131   Node_List* d_pk = my_pack(def);
1132   if (d_pk == NULL) {
1133     // check for scalar promotion
1134     Node* n = u_pk->at(0)->in(u_idx);
1135     for (uint i = 1; i < u_pk->size(); i++) {
1136       if (u_pk->at(i)->in(u_idx) != n) return false;
1137     }
1138     return true;
1139   }
1140   if (u_pk->size() != d_pk->size())
1141     return false;
1142   for (uint i = 0; i < u_pk->size(); i++) {
1143     Node* ui = u_pk->at(i);
1144     Node* di = d_pk->at(i);
1145     if (ui->in(u_idx) != di || alignment(ui) != alignment(di))
1146       return false;
1147   }
1148   return true;
1149 }
1150 
1151 //------------------------------construct_bb---------------------------
1152 // Construct reverse postorder list of block members
1153 void SuperWord::construct_bb() {
1154   Node* entry = bb();
1155 
1156   assert(_stk.length() == 0,            "stk is empty");
1157   assert(_block.length() == 0,          "block is empty");
1158   assert(_data_entry.length() == 0,     "data_entry is empty");
1159   assert(_mem_slice_head.length() == 0, "mem_slice_head is empty");
1160   assert(_mem_slice_tail.length() == 0, "mem_slice_tail is empty");
1161 
1162   // Find non-control nodes with no inputs from within block,
1163   // create a temporary map from node _idx to bb_idx for use
1164   // by the visited and post_visited sets,
1165   // and count number of nodes in block.
1166   int bb_ct = 0;
1167   for (uint i = 0; i < lpt()->_body.size(); i++ ) {
1168     Node *n = lpt()->_body.at(i);
1169     set_bb_idx(n, i); // Create a temporary map
1170     if (in_bb(n)) {
1171       bb_ct++;
1172       if (!n->is_CFG()) {
1173         bool found = false;
1174         for (uint j = 0; j < n->req(); j++) {
1175           Node* def = n->in(j);
1176           if (def && in_bb(def)) {
1177             found = true;
1178             break;
1179           }
1180         }
1181         if (!found) {
1182           assert(n != entry, "can't be entry");
1183           _data_entry.push(n);
1184         }
1185       }
1186     }
1187   }
1188 
1189   // Find memory slices (head and tail)
1190   for (DUIterator_Fast imax, i = lp()->fast_outs(imax); i < imax; i++) {
1191     Node *n = lp()->fast_out(i);
1192     if (in_bb(n) && (n->is_Phi() && n->bottom_type() == Type::MEMORY)) {
1193       Node* n_tail  = n->in(LoopNode::LoopBackControl);
1194       _mem_slice_head.push(n);
1195       _mem_slice_tail.push(n_tail);
1196     }
1197   }
1198 
1199   // Create an RPO list of nodes in block
1200 
1201   visited_clear();
1202   post_visited_clear();
1203 
1204   // Push all non-control nodes with no inputs from within block, then control entry
1205   for (int j = 0; j < _data_entry.length(); j++) {
1206     Node* n = _data_entry.at(j);
1207     visited_set(n);
1208     _stk.push(n);
1209   }
1210   visited_set(entry);
1211   _stk.push(entry);
1212 
1213   // Do a depth first walk over out edges
1214   int rpo_idx = bb_ct - 1;
1215   int size;
1216   while ((size = _stk.length()) > 0) {
1217     Node* n = _stk.top(); // Leave node on stack
1218     if (!visited_test_set(n)) {
1219       // forward arc in graph
1220     } else if (!post_visited_test(n)) {
1221       // cross or back arc
1222       for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
1223         Node *use = n->fast_out(i);
1224         if (in_bb(use) && !visited_test(use) &&
1225             // Don't go around backedge
1226             (!use->is_Phi() || n == entry)) {
1227           _stk.push(use);
1228         }
1229       }
1230       if (_stk.length() == size) {
1231         // There were no additional uses, post visit node now
1232         _stk.pop(); // Remove node from stack
1233         assert(rpo_idx >= 0, "");
1234         _block.at_put_grow(rpo_idx, n);
1235         rpo_idx--;
1236         post_visited_set(n);
1237         assert(rpo_idx >= 0 || _stk.is_empty(), "");
1238       }
1239     } else {
1240       _stk.pop(); // Remove post-visited node from stack
1241     }
1242   }
1243 
1244   // Create real map of block indices for nodes
1245   for (int j = 0; j < _block.length(); j++) {
1246     Node* n = _block.at(j);
1247     set_bb_idx(n, j);
1248   }
1249 
1250   initialize_bb(); // Ensure extra info is allocated.
1251 
1252 #ifndef PRODUCT
1253   if (TraceSuperWord) {
1254     print_bb();
1255     tty->print_cr("\ndata entry nodes: %s", _data_entry.length() > 0 ? "" : "NONE");
1256     for (int m = 0; m < _data_entry.length(); m++) {
1257       tty->print("%3d ", m);
1258       _data_entry.at(m)->dump();
1259     }
1260     tty->print_cr("\nmemory slices: %s", _mem_slice_head.length() > 0 ? "" : "NONE");
1261     for (int m = 0; m < _mem_slice_head.length(); m++) {
1262       tty->print("%3d ", m); _mem_slice_head.at(m)->dump();
1263       tty->print("    ");    _mem_slice_tail.at(m)->dump();
1264     }
1265   }
1266 #endif
1267   assert(rpo_idx == -1 && bb_ct == _block.length(), "all block members found");
1268 }
1269 
1270 //------------------------------initialize_bb---------------------------
1271 // Initialize per node info
1272 void SuperWord::initialize_bb() {
1273   Node* last = _block.at(_block.length() - 1);
1274   grow_node_info(bb_idx(last));
1275 }
1276 
1277 //------------------------------bb_insert_after---------------------------
1278 // Insert n into block after pos
1279 void SuperWord::bb_insert_after(Node* n, int pos) {
1280   int n_pos = pos + 1;
1281   // Make room
1282   for (int i = _block.length() - 1; i >= n_pos; i--) {
1283     _block.at_put_grow(i+1, _block.at(i));
1284   }
1285   for (int j = _node_info.length() - 1; j >= n_pos; j--) {
1286     _node_info.at_put_grow(j+1, _node_info.at(j));
1287   }
1288   // Set value
1289   _block.at_put_grow(n_pos, n);
1290   _node_info.at_put_grow(n_pos, SWNodeInfo::initial);
1291   // Adjust map from node->_idx to _block index
1292   for (int i = n_pos; i < _block.length(); i++) {
1293     set_bb_idx(_block.at(i), i);
1294   }
1295 }
1296 
1297 //------------------------------compute_max_depth---------------------------
1298 // Compute max depth for expressions from beginning of block
1299 // Use to prune search paths during test for independence.
1300 void SuperWord::compute_max_depth() {
1301   int ct = 0;
1302   bool again;
1303   do {
1304     again = false;
1305     for (int i = 0; i < _block.length(); i++) {
1306       Node* n = _block.at(i);
1307       if (!n->is_Phi()) {
1308         int d_orig = depth(n);
1309         int d_in   = 0;
1310         for (DepPreds preds(n, _dg); !preds.done(); preds.next()) {
1311           Node* pred = preds.current();
1312           if (in_bb(pred)) {
1313             d_in = MAX2(d_in, depth(pred));
1314           }
1315         }
1316         if (d_in + 1 != d_orig) {
1317           set_depth(n, d_in + 1);
1318           again = true;
1319         }
1320       }
1321     }
1322     ct++;
1323   } while (again);
1324 #ifndef PRODUCT
1325   if (TraceSuperWord && Verbose)
1326     tty->print_cr("compute_max_depth iterated: %d times", ct);
1327 #endif
1328 }
1329 
1330 //-------------------------compute_vector_element_type-----------------------
1331 // Compute necessary vector element type for expressions
1332 // This propagates backwards a narrower integer type when the
1333 // upper bits of the value are not needed.
1334 // Example:  char a,b,c;  a = b + c;
1335 // Normally the type of the add is integer, but for packed character
1336 // operations the type of the add needs to be char.
1337 void SuperWord::compute_vector_element_type() {
1338 #ifndef PRODUCT
1339   if (TraceSuperWord && Verbose)
1340     tty->print_cr("\ncompute_velt_type:");
1341 #endif
1342 
1343   // Initial type
1344   for (int i = 0; i < _block.length(); i++) {
1345     Node* n = _block.at(i);
1346     const Type* t  = n->is_Mem() ? Type::get_const_basic_type(n->as_Mem()->memory_type())
1347                                  : _igvn.type(n);
1348     const Type* vt = container_type(t);
1349     set_velt_type(n, vt);
1350   }
1351 
1352   // Propagate narrowed type backwards through operations
1353   // that don't depend on higher order bits
1354   for (int i = _block.length() - 1; i >= 0; i--) {
1355     Node* n = _block.at(i);
1356     // Only integer types need be examined
1357     if (n->bottom_type()->isa_int()) {
1358       uint start, end;
1359       vector_opd_range(n, &start, &end);
1360       const Type* vt = velt_type(n);
1361 
1362       for (uint j = start; j < end; j++) {
1363         Node* in  = n->in(j);
1364         // Don't propagate through a type conversion
1365         if (n->bottom_type() != in->bottom_type())
1366           continue;
1367         switch(in->Opcode()) {
1368         case Op_AddI:    case Op_AddL:
1369         case Op_SubI:    case Op_SubL:
1370         case Op_MulI:    case Op_MulL:
1371         case Op_AndI:    case Op_AndL:
1372         case Op_OrI:     case Op_OrL:
1373         case Op_XorI:    case Op_XorL:
1374         case Op_LShiftI: case Op_LShiftL:
1375         case Op_CMoveI:  case Op_CMoveL:
1376           if (in_bb(in)) {
1377             bool same_type = true;
1378             for (DUIterator_Fast kmax, k = in->fast_outs(kmax); k < kmax; k++) {
1379               Node *use = in->fast_out(k);
1380               if (!in_bb(use) || velt_type(use) != vt) {
1381                 same_type = false;
1382                 break;
1383               }
1384             }
1385             if (same_type) {
1386               set_velt_type(in, vt);
1387             }
1388           }
1389         }
1390       }
1391     }
1392   }
1393 #ifndef PRODUCT
1394   if (TraceSuperWord && Verbose) {
1395     for (int i = 0; i < _block.length(); i++) {
1396       Node* n = _block.at(i);
1397       velt_type(n)->dump();
1398       tty->print("\t");
1399       n->dump();
1400     }
1401   }
1402 #endif
1403 }
1404 
1405 //------------------------------memory_alignment---------------------------
1406 // Alignment within a vector memory reference
1407 int SuperWord::memory_alignment(MemNode* s, int iv_adjust_in_bytes) {
1408   SWPointer p(s, this);
1409   if (!p.valid()) {
1410     return bottom_align;
1411   }
1412   int offset  = p.offset_in_bytes();
1413   offset     += iv_adjust_in_bytes;
1414   int off_rem = offset % vector_width_in_bytes();
1415   int off_mod = off_rem >= 0 ? off_rem : off_rem + vector_width_in_bytes();
1416   return off_mod;
1417 }
1418 
1419 //---------------------------container_type---------------------------
1420 // Smallest type containing range of values
1421 const Type* SuperWord::container_type(const Type* t) {
1422   if (t->isa_aryptr()) {
1423     t = t->is_aryptr()->elem();
1424   }
1425   if (t->basic_type() == T_INT) {
1426     if (t->higher_equal(TypeInt::BOOL))  return TypeInt::BOOL;
1427     if (t->higher_equal(TypeInt::BYTE))  return TypeInt::BYTE;
1428     if (t->higher_equal(TypeInt::CHAR))  return TypeInt::CHAR;
1429     if (t->higher_equal(TypeInt::SHORT)) return TypeInt::SHORT;
1430     return TypeInt::INT;
1431   }
1432   return t;
1433 }
1434 
1435 //-------------------------vector_opd_range-----------------------
1436 // (Start, end] half-open range defining which operands are vector
1437 void SuperWord::vector_opd_range(Node* n, uint* start, uint* end) {
1438   switch (n->Opcode()) {
1439   case Op_LoadB:   case Op_LoadC:
1440   case Op_LoadI:   case Op_LoadL:
1441   case Op_LoadF:   case Op_LoadD:
1442   case Op_LoadP:
1443     *start = 0;
1444     *end   = 0;
1445     return;
1446   case Op_StoreB:  case Op_StoreC:
1447   case Op_StoreI:  case Op_StoreL:
1448   case Op_StoreF:  case Op_StoreD:
1449   case Op_StoreP:
1450     *start = MemNode::ValueIn;
1451     *end   = *start + 1;
1452     return;
1453   case Op_LShiftI: case Op_LShiftL:
1454     *start = 1;
1455     *end   = 2;
1456     return;
1457   case Op_CMoveI:  case Op_CMoveL:  case Op_CMoveF:  case Op_CMoveD:
1458     *start = 2;
1459     *end   = n->req();
1460     return;
1461   }
1462   *start = 1;
1463   *end   = n->req(); // default is all operands
1464 }
1465 
1466 //------------------------------in_packset---------------------------
1467 // Are s1 and s2 in a pack pair and ordered as s1,s2?
1468 bool SuperWord::in_packset(Node* s1, Node* s2) {
1469   for (int i = 0; i < _packset.length(); i++) {
1470     Node_List* p = _packset.at(i);
1471     assert(p->size() == 2, "must be");
1472     if (p->at(0) == s1 && p->at(p->size()-1) == s2) {
1473       return true;
1474     }
1475   }
1476   return false;
1477 }
1478 
1479 //------------------------------in_pack---------------------------
1480 // Is s in pack p?
1481 Node_List* SuperWord::in_pack(Node* s, Node_List* p) {
1482   for (uint i = 0; i < p->size(); i++) {
1483     if (p->at(i) == s) {
1484       return p;
1485     }
1486   }
1487   return NULL;
1488 }
1489 
1490 //------------------------------remove_pack_at---------------------------
1491 // Remove the pack at position pos in the packset
1492 void SuperWord::remove_pack_at(int pos) {
1493   Node_List* p = _packset.at(pos);
1494   for (uint i = 0; i < p->size(); i++) {
1495     Node* s = p->at(i);
1496     set_my_pack(s, NULL);
1497   }
1498   _packset.remove_at(pos);
1499 }
1500 
1501 //------------------------------executed_first---------------------------
1502 // Return the node executed first in pack p.  Uses the RPO block list
1503 // to determine order.
1504 Node* SuperWord::executed_first(Node_List* p) {
1505   Node* n = p->at(0);
1506   int n_rpo = bb_idx(n);
1507   for (uint i = 1; i < p->size(); i++) {
1508     Node* s = p->at(i);
1509     int s_rpo = bb_idx(s);
1510     if (s_rpo < n_rpo) {
1511       n = s;
1512       n_rpo = s_rpo;
1513     }
1514   }
1515   return n;
1516 }
1517 
1518 //------------------------------executed_last---------------------------
1519 // Return the node executed last in pack p.
1520 Node* SuperWord::executed_last(Node_List* p) {
1521   Node* n = p->at(0);
1522   int n_rpo = bb_idx(n);
1523   for (uint i = 1; i < p->size(); i++) {
1524     Node* s = p->at(i);
1525     int s_rpo = bb_idx(s);
1526     if (s_rpo > n_rpo) {
1527       n = s;
1528       n_rpo = s_rpo;
1529     }
1530   }
1531   return n;
1532 }
1533 
1534 //----------------------------align_initial_loop_index---------------------------
1535 // Adjust pre-loop limit so that in main loop, a load/store reference
1536 // to align_to_ref will be a position zero in the vector.
1537 //   (iv + k) mod vector_align == 0
1538 void SuperWord::align_initial_loop_index(MemNode* align_to_ref) {
1539   CountedLoopNode *main_head = lp()->as_CountedLoop();
1540   assert(main_head->is_main_loop(), "");
1541   CountedLoopEndNode* pre_end = get_pre_loop_end(main_head);
1542   assert(pre_end != NULL, "");
1543   Node *pre_opaq1 = pre_end->limit();
1544   assert(pre_opaq1->Opcode() == Op_Opaque1, "");
1545   Opaque1Node *pre_opaq = (Opaque1Node*)pre_opaq1;
1546   Node *lim0 = pre_opaq->in(1);
1547 
1548   // Where we put new limit calculations
1549   Node *pre_ctrl = pre_end->loopnode()->in(LoopNode::EntryControl);
1550 
1551   // Ensure the original loop limit is available from the
1552   // pre-loop Opaque1 node.
1553   Node *orig_limit = pre_opaq->original_loop_limit();
1554   assert(orig_limit != NULL && _igvn.type(orig_limit) != Type::TOP, "");
1555 
1556   SWPointer align_to_ref_p(align_to_ref, this);
1557 
1558   // Given:
1559   //     lim0 == original pre loop limit
1560   //     V == v_align (power of 2)
1561   //     invar == extra invariant piece of the address expression
1562   //     e == k [ +/- invar ]
1563   //
1564   // When reassociating expressions involving '%' the basic rules are:
1565   //     (a - b) % k == 0   =>  a % k == b % k
1566   // and:
1567   //     (a + b) % k == 0   =>  a % k == (k - b) % k
1568   //
1569   // For stride > 0 && scale > 0,
1570   //   Derive the new pre-loop limit "lim" such that the two constraints:
1571   //     (1) lim = lim0 + N           (where N is some positive integer < V)
1572   //     (2) (e + lim) % V == 0
1573   //   are true.
1574   //
1575   //   Substituting (1) into (2),
1576   //     (e + lim0 + N) % V == 0
1577   //   solve for N:
1578   //     N = (V - (e + lim0)) % V
1579   //   substitute back into (1), so that new limit
1580   //     lim = lim0 + (V - (e + lim0)) % V
1581   //
1582   // For stride > 0 && scale < 0
1583   //   Constraints:
1584   //     lim = lim0 + N
1585   //     (e - lim) % V == 0
1586   //   Solving for lim:
1587   //     (e - lim0 - N) % V == 0
1588   //     N = (e - lim0) % V
1589   //     lim = lim0 + (e - lim0) % V
1590   //
1591   // For stride < 0 && scale > 0
1592   //   Constraints:
1593   //     lim = lim0 - N
1594   //     (e + lim) % V == 0
1595   //   Solving for lim:
1596   //     (e + lim0 - N) % V == 0
1597   //     N = (e + lim0) % V
1598   //     lim = lim0 - (e + lim0) % V
1599   //
1600   // For stride < 0 && scale < 0
1601   //   Constraints:
1602   //     lim = lim0 - N
1603   //     (e - lim) % V == 0
1604   //   Solving for lim:
1605   //     (e - lim0 + N) % V == 0
1606   //     N = (V - (e - lim0)) % V
1607   //     lim = lim0 - (V - (e - lim0)) % V
1608 
1609   int stride   = iv_stride();
1610   int scale    = align_to_ref_p.scale_in_bytes();
1611   int elt_size = align_to_ref_p.memory_size();
1612   int v_align  = vector_width_in_bytes() / elt_size;
1613   int k        = align_to_ref_p.offset_in_bytes() / elt_size;
1614 
1615   Node *kn   = _igvn.intcon(k);
1616 
1617   Node *e = kn;
1618   if (align_to_ref_p.invar() != NULL) {
1619     // incorporate any extra invariant piece producing k +/- invar >>> log2(elt)
1620     Node* log2_elt = _igvn.intcon(exact_log2(elt_size));
1621     Node* aref     = new (_phase->C, 3) URShiftINode(align_to_ref_p.invar(), log2_elt);
1622     _phase->_igvn.register_new_node_with_optimizer(aref);
1623     _phase->set_ctrl(aref, pre_ctrl);
1624     if (align_to_ref_p.negate_invar()) {
1625       e = new (_phase->C, 3) SubINode(e, aref);
1626     } else {
1627       e = new (_phase->C, 3) AddINode(e, aref);
1628     }
1629     _phase->_igvn.register_new_node_with_optimizer(e);
1630     _phase->set_ctrl(e, pre_ctrl);
1631   }
1632 
1633   // compute e +/- lim0
1634   if (scale < 0) {
1635     e = new (_phase->C, 3) SubINode(e, lim0);
1636   } else {
1637     e = new (_phase->C, 3) AddINode(e, lim0);
1638   }
1639   _phase->_igvn.register_new_node_with_optimizer(e);
1640   _phase->set_ctrl(e, pre_ctrl);
1641 
1642   if (stride * scale > 0) {
1643     // compute V - (e +/- lim0)
1644     Node* va  = _igvn.intcon(v_align);
1645     e = new (_phase->C, 3) SubINode(va, e);
1646     _phase->_igvn.register_new_node_with_optimizer(e);
1647     _phase->set_ctrl(e, pre_ctrl);
1648   }
1649   // compute N = (exp) % V
1650   Node* va_msk = _igvn.intcon(v_align - 1);
1651   Node* N = new (_phase->C, 3) AndINode(e, va_msk);
1652   _phase->_igvn.register_new_node_with_optimizer(N);
1653   _phase->set_ctrl(N, pre_ctrl);
1654 
1655   //   substitute back into (1), so that new limit
1656   //     lim = lim0 + N
1657   Node* lim;
1658   if (stride < 0) {
1659     lim = new (_phase->C, 3) SubINode(lim0, N);
1660   } else {
1661     lim = new (_phase->C, 3) AddINode(lim0, N);
1662   }
1663   _phase->_igvn.register_new_node_with_optimizer(lim);
1664   _phase->set_ctrl(lim, pre_ctrl);
1665   Node* constrained =
1666     (stride > 0) ? (Node*) new (_phase->C,3) MinINode(lim, orig_limit)
1667                  : (Node*) new (_phase->C,3) MaxINode(lim, orig_limit);
1668   _phase->_igvn.register_new_node_with_optimizer(constrained);
1669   _phase->set_ctrl(constrained, pre_ctrl);
1670   _igvn.hash_delete(pre_opaq);
1671   pre_opaq->set_req(1, constrained);
1672 }
1673 
1674 //----------------------------get_pre_loop_end---------------------------
1675 // Find pre loop end from main loop.  Returns null if none.
1676 CountedLoopEndNode* SuperWord::get_pre_loop_end(CountedLoopNode *cl) {
1677   Node *ctrl = cl->in(LoopNode::EntryControl);
1678   if (!ctrl->is_IfTrue() && !ctrl->is_IfFalse()) return NULL;
1679   Node *iffm = ctrl->in(0);
1680   if (!iffm->is_If()) return NULL;
1681   Node *p_f = iffm->in(0);
1682   if (!p_f->is_IfFalse()) return NULL;
1683   if (!p_f->in(0)->is_CountedLoopEnd()) return NULL;
1684   CountedLoopEndNode *pre_end = p_f->in(0)->as_CountedLoopEnd();
1685   if (!pre_end->loopnode()->is_pre_loop()) return NULL;
1686   return pre_end;
1687 }
1688 
1689 
1690 //------------------------------init---------------------------
1691 void SuperWord::init() {
1692   _dg.init();
1693   _packset.clear();
1694   _disjoint_ptrs.clear();
1695   _block.clear();
1696   _data_entry.clear();
1697   _mem_slice_head.clear();
1698   _mem_slice_tail.clear();
1699   _node_info.clear();
1700   _align_to_ref = NULL;
1701   _lpt = NULL;
1702   _lp = NULL;
1703   _bb = NULL;
1704   _iv = NULL;
1705 }
1706 
1707 //------------------------------print_packset---------------------------
1708 void SuperWord::print_packset() {
1709 #ifndef PRODUCT
1710   tty->print_cr("packset");
1711   for (int i = 0; i < _packset.length(); i++) {
1712     tty->print_cr("Pack: %d", i);
1713     Node_List* p = _packset.at(i);
1714     print_pack(p);
1715   }
1716 #endif
1717 }
1718 
1719 //------------------------------print_pack---------------------------
1720 void SuperWord::print_pack(Node_List* p) {
1721   for (uint i = 0; i < p->size(); i++) {
1722     print_stmt(p->at(i));
1723   }
1724 }
1725 
1726 //------------------------------print_bb---------------------------
1727 void SuperWord::print_bb() {
1728 #ifndef PRODUCT
1729   tty->print_cr("\nBlock");
1730   for (int i = 0; i < _block.length(); i++) {
1731     Node* n = _block.at(i);
1732     tty->print("%d ", i);
1733     if (n) {
1734       n->dump();
1735     }
1736   }
1737 #endif
1738 }
1739 
1740 //------------------------------print_stmt---------------------------
1741 void SuperWord::print_stmt(Node* s) {
1742 #ifndef PRODUCT
1743   tty->print(" align: %d \t", alignment(s));
1744   s->dump();
1745 #endif
1746 }
1747 
1748 //------------------------------blank---------------------------
1749 char* SuperWord::blank(uint depth) {
1750   static char blanks[101];
1751   assert(depth < 101, "too deep");
1752   for (uint i = 0; i < depth; i++) blanks[i] = ' ';
1753   blanks[depth] = '\0';
1754   return blanks;
1755 }
1756 
1757 
1758 //==============================SWPointer===========================
1759 
1760 //----------------------------SWPointer------------------------
1761 SWPointer::SWPointer(MemNode* mem, SuperWord* slp) :
1762   _mem(mem), _slp(slp),  _base(NULL),  _adr(NULL),
1763   _scale(0), _offset(0), _invar(NULL), _negate_invar(false) {
1764 
1765   Node* adr = mem->in(MemNode::Address);
1766   if (!adr->is_AddP()) {
1767     assert(!valid(), "too complex");
1768     return;
1769   }
1770   // Match AddP(base, AddP(ptr, k*iv [+ invariant]), constant)
1771   Node* base = adr->in(AddPNode::Base);
1772   for (int i = 0; i < 3; i++) {
1773     if (!scaled_iv_plus_offset(adr->in(AddPNode::Offset))) {
1774       assert(!valid(), "too complex");
1775       return;
1776     }
1777     adr = adr->in(AddPNode::Address);
1778     if (base == adr || !adr->is_AddP()) {
1779       break; // stop looking at addp's
1780     }
1781   }
1782   _base = base;
1783   _adr  = adr;
1784   assert(valid(), "Usable");
1785 }
1786 
1787 // Following is used to create a temporary object during
1788 // the pattern match of an address expression.
1789 SWPointer::SWPointer(SWPointer* p) :
1790   _mem(p->_mem), _slp(p->_slp),  _base(NULL),  _adr(NULL),
1791   _scale(0), _offset(0), _invar(NULL), _negate_invar(false) {}
1792 
1793 //------------------------scaled_iv_plus_offset--------------------
1794 // Match: k*iv + offset
1795 // where: k is a constant that maybe zero, and
1796 //        offset is (k2 [+/- invariant]) where k2 maybe zero and invariant is optional
1797 bool SWPointer::scaled_iv_plus_offset(Node* n) {
1798   if (scaled_iv(n)) {
1799     return true;
1800   }
1801   if (offset_plus_k(n)) {
1802     return true;
1803   }
1804   int opc = n->Opcode();
1805   if (opc == Op_AddI) {
1806     if (scaled_iv(n->in(1)) && offset_plus_k(n->in(2))) {
1807       return true;
1808     }
1809     if (scaled_iv(n->in(2)) && offset_plus_k(n->in(1))) {
1810       return true;
1811     }
1812   } else if (opc == Op_SubI) {
1813     if (scaled_iv(n->in(1)) && offset_plus_k(n->in(2), true)) {
1814       return true;
1815     }
1816     if (scaled_iv(n->in(2)) && offset_plus_k(n->in(1))) {
1817       _scale *= -1;
1818       return true;
1819     }
1820   }
1821   return false;
1822 }
1823 
1824 //----------------------------scaled_iv------------------------
1825 // Match: k*iv where k is a constant that's not zero
1826 bool SWPointer::scaled_iv(Node* n) {
1827   if (_scale != 0) {
1828     return false;  // already found a scale
1829   }
1830   if (n == iv()) {
1831     _scale = 1;
1832     return true;
1833   }
1834   int opc = n->Opcode();
1835   if (opc == Op_MulI) {
1836     if (n->in(1) == iv() && n->in(2)->is_Con()) {
1837       _scale = n->in(2)->get_int();
1838       return true;
1839     } else if (n->in(2) == iv() && n->in(1)->is_Con()) {
1840       _scale = n->in(1)->get_int();
1841       return true;
1842     }
1843   } else if (opc == Op_LShiftI) {
1844     if (n->in(1) == iv() && n->in(2)->is_Con()) {
1845       _scale = 1 << n->in(2)->get_int();
1846       return true;
1847     }
1848   } else if (opc == Op_ConvI2L) {
1849     if (scaled_iv_plus_offset(n->in(1))) {
1850       return true;
1851     }
1852   } else if (opc == Op_LShiftL) {
1853     if (!has_iv() && _invar == NULL) {
1854       // Need to preserve the current _offset value, so
1855       // create a temporary object for this expression subtree.
1856       // Hacky, so should re-engineer the address pattern match.
1857       SWPointer tmp(this);
1858       if (tmp.scaled_iv_plus_offset(n->in(1))) {
1859         if (tmp._invar == NULL) {
1860           int mult = 1 << n->in(2)->get_int();
1861           _scale   = tmp._scale  * mult;
1862           _offset += tmp._offset * mult;
1863           return true;
1864         }
1865       }
1866     }
1867   }
1868   return false;
1869 }
1870 
1871 //----------------------------offset_plus_k------------------------
1872 // Match: offset is (k [+/- invariant])
1873 // where k maybe zero and invariant is optional, but not both.
1874 bool SWPointer::offset_plus_k(Node* n, bool negate) {
1875   int opc = n->Opcode();
1876   if (opc == Op_ConI) {
1877     _offset += negate ? -(n->get_int()) : n->get_int();
1878     return true;
1879   } else if (opc == Op_ConL) {
1880     // Okay if value fits into an int
1881     const TypeLong* t = n->find_long_type();
1882     if (t->higher_equal(TypeLong::INT)) {
1883       jlong loff = n->get_long();
1884       jint  off  = (jint)loff;
1885       _offset += negate ? -off : loff;
1886       return true;
1887     }
1888     return false;
1889   }
1890   if (_invar != NULL) return false; // already have an invariant
1891   if (opc == Op_AddI) {
1892     if (n->in(2)->is_Con() && invariant(n->in(1))) {
1893       _negate_invar = negate;
1894       _invar = n->in(1);
1895       _offset += negate ? -(n->in(2)->get_int()) : n->in(2)->get_int();
1896       return true;
1897     } else if (n->in(1)->is_Con() && invariant(n->in(2))) {
1898       _offset += negate ? -(n->in(1)->get_int()) : n->in(1)->get_int();
1899       _negate_invar = negate;
1900       _invar = n->in(2);
1901       return true;
1902     }
1903   }
1904   if (opc == Op_SubI) {
1905     if (n->in(2)->is_Con() && invariant(n->in(1))) {
1906       _negate_invar = negate;
1907       _invar = n->in(1);
1908       _offset += !negate ? -(n->in(2)->get_int()) : n->in(2)->get_int();
1909       return true;
1910     } else if (n->in(1)->is_Con() && invariant(n->in(2))) {
1911       _offset += negate ? -(n->in(1)->get_int()) : n->in(1)->get_int();
1912       _negate_invar = !negate;
1913       _invar = n->in(2);
1914       return true;
1915     }
1916   }
1917   if (invariant(n)) {
1918     _negate_invar = negate;
1919     _invar = n;
1920     return true;
1921   }
1922   return false;
1923 }
1924 
1925 //----------------------------print------------------------
1926 void SWPointer::print() {
1927 #ifndef PRODUCT
1928   tty->print("base: %d  adr: %d  scale: %d  offset: %d  invar: %c%d\n",
1929              _base != NULL ? _base->_idx : 0,
1930              _adr  != NULL ? _adr->_idx  : 0,
1931              _scale, _offset,
1932              _negate_invar?'-':'+',
1933              _invar != NULL ? _invar->_idx : 0);
1934 #endif
1935 }
1936 
1937 // ========================= OrderedPair =====================
1938 
1939 const OrderedPair OrderedPair::initial;
1940 
1941 // ========================= SWNodeInfo =====================
1942 
1943 const SWNodeInfo SWNodeInfo::initial;
1944 
1945 
1946 // ============================ DepGraph ===========================
1947 
1948 //------------------------------make_node---------------------------
1949 // Make a new dependence graph node for an ideal node.
1950 DepMem* DepGraph::make_node(Node* node) {
1951   DepMem* m = new (_arena) DepMem(node);
1952   if (node != NULL) {
1953     assert(_map.at_grow(node->_idx) == NULL, "one init only");
1954     _map.at_put_grow(node->_idx, m);
1955   }
1956   return m;
1957 }
1958 
1959 //------------------------------make_edge---------------------------
1960 // Make a new dependence graph edge from dpred -> dsucc
1961 DepEdge* DepGraph::make_edge(DepMem* dpred, DepMem* dsucc) {
1962   DepEdge* e = new (_arena) DepEdge(dpred, dsucc, dsucc->in_head(), dpred->out_head());
1963   dpred->set_out_head(e);
1964   dsucc->set_in_head(e);
1965   return e;
1966 }
1967 
1968 // ========================== DepMem ========================
1969 
1970 //------------------------------in_cnt---------------------------
1971 int DepMem::in_cnt() {
1972   int ct = 0;
1973   for (DepEdge* e = _in_head; e != NULL; e = e->next_in()) ct++;
1974   return ct;
1975 }
1976 
1977 //------------------------------out_cnt---------------------------
1978 int DepMem::out_cnt() {
1979   int ct = 0;
1980   for (DepEdge* e = _out_head; e != NULL; e = e->next_out()) ct++;
1981   return ct;
1982 }
1983 
1984 //------------------------------print-----------------------------
1985 void DepMem::print() {
1986 #ifndef PRODUCT
1987   tty->print("  DepNode %d (", _node->_idx);
1988   for (DepEdge* p = _in_head; p != NULL; p = p->next_in()) {
1989     Node* pred = p->pred()->node();
1990     tty->print(" %d", pred != NULL ? pred->_idx : 0);
1991   }
1992   tty->print(") [");
1993   for (DepEdge* s = _out_head; s != NULL; s = s->next_out()) {
1994     Node* succ = s->succ()->node();
1995     tty->print(" %d", succ != NULL ? succ->_idx : 0);
1996   }
1997   tty->print_cr(" ]");
1998 #endif
1999 }
2000 
2001 // =========================== DepEdge =========================
2002 
2003 //------------------------------DepPreds---------------------------
2004 void DepEdge::print() {
2005 #ifndef PRODUCT
2006   tty->print_cr("DepEdge: %d [ %d ]", _pred->node()->_idx, _succ->node()->_idx);
2007 #endif
2008 }
2009 
2010 // =========================== DepPreds =========================
2011 // Iterator over predecessor edges in the dependence graph.
2012 
2013 //------------------------------DepPreds---------------------------
2014 DepPreds::DepPreds(Node* n, DepGraph& dg) {
2015   _n = n;
2016   _done = false;
2017   if (_n->is_Store() || _n->is_Load()) {
2018     _next_idx = MemNode::Address;
2019     _end_idx  = n->req();
2020     _dep_next = dg.dep(_n)->in_head();
2021   } else if (_n->is_Mem()) {
2022     _next_idx = 0;
2023     _end_idx  = 0;
2024     _dep_next = dg.dep(_n)->in_head();
2025   } else {
2026     _next_idx = 1;
2027     _end_idx  = _n->req();
2028     _dep_next = NULL;
2029   }
2030   next();
2031 }
2032 
2033 //------------------------------next---------------------------
2034 void DepPreds::next() {
2035   if (_dep_next != NULL) {
2036     _current  = _dep_next->pred()->node();
2037     _dep_next = _dep_next->next_in();
2038   } else if (_next_idx < _end_idx) {
2039     _current  = _n->in(_next_idx++);
2040   } else {
2041     _done = true;
2042   }
2043 }
2044 
2045 // =========================== DepSuccs =========================
2046 // Iterator over successor edges in the dependence graph.
2047 
2048 //------------------------------DepSuccs---------------------------
2049 DepSuccs::DepSuccs(Node* n, DepGraph& dg) {
2050   _n = n;
2051   _done = false;
2052   if (_n->is_Load()) {
2053     _next_idx = 0;
2054     _end_idx  = _n->outcnt();
2055     _dep_next = dg.dep(_n)->out_head();
2056   } else if (_n->is_Mem() || _n->is_Phi() && _n->bottom_type() == Type::MEMORY) {
2057     _next_idx = 0;
2058     _end_idx  = 0;
2059     _dep_next = dg.dep(_n)->out_head();
2060   } else {
2061     _next_idx = 0;
2062     _end_idx  = _n->outcnt();
2063     _dep_next = NULL;
2064   }
2065   next();
2066 }
2067 
2068 //-------------------------------next---------------------------
2069 void DepSuccs::next() {
2070   if (_dep_next != NULL) {
2071     _current  = _dep_next->succ()->node();
2072     _dep_next = _dep_next->next_out();
2073   } else if (_next_idx < _end_idx) {
2074     _current  = _n->raw_out(_next_idx++);
2075   } else {
2076     _done = true;
2077   }
2078 }