1 /*
   2  * Copyright (c) 2007, 2012, Oracle and/or its affiliates. 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  */
  23 
  24 #include "precompiled.hpp"
  25 #include "compiler/compileLog.hpp"
  26 #include "libadt/vectset.hpp"
  27 #include "memory/allocation.inline.hpp"
  28 #include "opto/addnode.hpp"
  29 #include "opto/callnode.hpp"
  30 #include "opto/divnode.hpp"
  31 #include "opto/matcher.hpp"
  32 #include "opto/memnode.hpp"
  33 #include "opto/mulnode.hpp"
  34 #include "opto/opcodes.hpp"
  35 #include "opto/superword.hpp"
  36 #include "opto/vectornode.hpp"
  37 
  38 //
  39 //                  S U P E R W O R D   T R A N S F O R M
  40 //=============================================================================
  41 
  42 //------------------------------SuperWord---------------------------
  43 SuperWord::SuperWord(PhaseIdealLoop* phase) :
  44   _phase(phase),
  45   _igvn(phase->_igvn),
  46   _arena(phase->C->comp_arena()),
  47   _packset(arena(), 8,  0, NULL),         // packs for the current block
  48   _bb_idx(arena(), (int)(1.10 * phase->C->unique()), 0, 0), // node idx to index in bb
  49   _block(arena(), 8,  0, NULL),           // nodes in current block
  50   _data_entry(arena(), 8,  0, NULL),      // nodes with all inputs from outside
  51   _mem_slice_head(arena(), 8,  0, NULL),  // memory slice heads
  52   _mem_slice_tail(arena(), 8,  0, NULL),  // memory slice tails
  53   _node_info(arena(), 8,  0, SWNodeInfo::initial), // info needed per node
  54   _align_to_ref(NULL),                    // memory reference to align vectors to
  55   _disjoint_ptrs(arena(), 8,  0, OrderedPair::initial), // runtime disambiguated pointer pairs
  56   _dg(_arena),                            // dependence graph
  57   _visited(arena()),                      // visited node set
  58   _post_visited(arena()),                 // post visited node set
  59   _n_idx_list(arena(), 8),                // scratch list of (node,index) pairs
  60   _stk(arena(), 8, 0, NULL),              // scratch stack of nodes
  61   _nlist(arena(), 8, 0, NULL),            // scratch list of nodes
  62   _lpt(NULL),                             // loop tree node
  63   _lp(NULL),                              // LoopNode
  64   _bb(NULL),                              // basic block
  65   _iv(NULL)                               // induction var
  66 {}
  67 
  68 //------------------------------transform_loop---------------------------
  69 void SuperWord::transform_loop(IdealLoopTree* lpt) {
  70   assert(UseSuperWord, "should be");
  71   // Do vectors exist on this architecture?
  72   if (Matcher::vector_width_in_bytes(T_BYTE) < 2) return;
  73 
  74   assert(lpt->_head->is_CountedLoop(), "must be");
  75   CountedLoopNode *cl = lpt->_head->as_CountedLoop();
  76 
  77   if (!cl->is_valid_counted_loop()) return; // skip malformed counted loop
  78 
  79   if (!cl->is_main_loop() ) return; // skip normal, pre, and post loops
  80 
  81   // Check for no control flow in body (other than exit)
  82   Node *cl_exit = cl->loopexit();
  83   if (cl_exit->in(0) != lpt->_head) return;
  84 
  85   // Make sure the are no extra control users of the loop backedge
  86   if (cl->back_control()->outcnt() != 1) {
  87     return;
  88   }
  89 
  90   // Check for pre-loop ending with CountedLoopEnd(Bool(Cmp(x,Opaque1(limit))))
  91   CountedLoopEndNode* pre_end = get_pre_loop_end(cl);
  92   if (pre_end == NULL) return;
  93   Node *pre_opaq1 = pre_end->limit();
  94   if (pre_opaq1->Opcode() != Op_Opaque1) return;
  95 
  96   init(); // initialize data structures
  97 
  98   set_lpt(lpt);
  99   set_lp(cl);
 100 
 101   // For now, define one block which is the entire loop body
 102   set_bb(cl);
 103 
 104   assert(_packset.length() == 0, "packset must be empty");
 105   SLP_extract();
 106 }
 107 
 108 //------------------------------SLP_extract---------------------------
 109 // Extract the superword level parallelism
 110 //
 111 // 1) A reverse post-order of nodes in the block is constructed.  By scanning
 112 //    this list from first to last, all definitions are visited before their uses.
 113 //
 114 // 2) A point-to-point dependence graph is constructed between memory references.
 115 //    This simplies the upcoming "independence" checker.
 116 //
 117 // 3) The maximum depth in the node graph from the beginning of the block
 118 //    to each node is computed.  This is used to prune the graph search
 119 //    in the independence checker.
 120 //
 121 // 4) For integer types, the necessary bit width is propagated backwards
 122 //    from stores to allow packed operations on byte, char, and short
 123 //    integers.  This reverses the promotion to type "int" that javac
 124 //    did for operations like: char c1,c2,c3;  c1 = c2 + c3.
 125 //
 126 // 5) One of the memory references is picked to be an aligned vector reference.
 127 //    The pre-loop trip count is adjusted to align this reference in the
 128 //    unrolled body.
 129 //
 130 // 6) The initial set of pack pairs is seeded with memory references.
 131 //
 132 // 7) The set of pack pairs is extended by following use->def and def->use links.
 133 //
 134 // 8) The pairs are combined into vector sized packs.
 135 //
 136 // 9) Reorder the memory slices to co-locate members of the memory packs.
 137 //
 138 // 10) Generate ideal vector nodes for the final set of packs and where necessary,
 139 //    inserting scalar promotion, vector creation from multiple scalars, and
 140 //    extraction of scalar values from vectors.
 141 //
 142 void SuperWord::SLP_extract() {
 143 
 144   // Ready the block
 145 
 146   construct_bb();
 147 
 148   dependence_graph();
 149 
 150   compute_max_depth();
 151 
 152   compute_vector_element_type();
 153 
 154   // Attempt vectorization
 155 
 156   find_adjacent_refs();
 157 
 158   extend_packlist();
 159 
 160   combine_packs();
 161 
 162   construct_my_pack_map();
 163 
 164   filter_packs();
 165 
 166   schedule();
 167 
 168   output();
 169 }
 170 
 171 //------------------------------find_adjacent_refs---------------------------
 172 // Find the adjacent memory references and create pack pairs for them.
 173 // This is the initial set of packs that will then be extended by
 174 // following use->def and def->use links.  The align positions are
 175 // assigned relative to the reference "align_to_ref"
 176 void SuperWord::find_adjacent_refs() {
 177   // Get list of memory operations
 178   Node_List memops;
 179   for (int i = 0; i < _block.length(); i++) {
 180     Node* n = _block.at(i);
 181     if (n->is_Mem() && !n->is_LoadStore() && in_bb(n) &&
 182         is_java_primitive(n->as_Mem()->memory_type())) {
 183       int align = memory_alignment(n->as_Mem(), 0);
 184       if (align != bottom_align) {
 185         memops.push(n);
 186       }
 187     }
 188   }
 189 
 190   Node_List align_to_refs;
 191   int best_iv_adjustment = 0;
 192   MemNode* best_align_to_mem_ref = NULL;
 193 
 194   while (memops.size() != 0) {
 195     // Find a memory reference to align to.
 196     MemNode* mem_ref = find_align_to_ref(memops);
 197     if (mem_ref == NULL) break;
 198     align_to_refs.push(mem_ref);
 199     int iv_adjustment = get_iv_adjustment(mem_ref);
 200 
 201     if (best_align_to_mem_ref == NULL) {
 202       // Set memory reference which is the best from all memory operations
 203       // to be used for alignment. The pre-loop trip count is modified to align
 204       // this reference to a vector-aligned address.
 205       best_align_to_mem_ref = mem_ref;
 206       best_iv_adjustment = iv_adjustment;
 207     }
 208 
 209     SWPointer align_to_ref_p(mem_ref, this);
 210     // Set alignment relative to "align_to_ref" for all related memory operations.
 211     for (int i = memops.size() - 1; i >= 0; i--) {
 212       MemNode* s = memops.at(i)->as_Mem();
 213       if (isomorphic(s, mem_ref)) {
 214         SWPointer p2(s, this);
 215         if (p2.comparable(align_to_ref_p)) {
 216           int align = memory_alignment(s, iv_adjustment);
 217           set_alignment(s, align);
 218         }
 219       }
 220     }
 221 
 222     // Create initial pack pairs of memory operations for which
 223     // alignment is set and vectors will be aligned.
 224     bool create_pack = true;
 225     if (memory_alignment(mem_ref, best_iv_adjustment) == 0) {
 226       if (!Matcher::misaligned_vectors_ok()) {
 227         int vw = vector_width(mem_ref);
 228         int vw_best = vector_width(best_align_to_mem_ref);
 229         if (vw > vw_best) {
 230           // Do not vectorize a memory access with more elements per vector
 231           // if unaligned memory access is not allowed because number of
 232           // iterations in pre-loop will be not enough to align it.
 233           create_pack = false;
 234         }
 235       }
 236     } else {
 237       if (same_velt_type(mem_ref, best_align_to_mem_ref)) {
 238         // Can't allow vectorization of unaligned memory accesses with the
 239         // same type since it could be overlapped accesses to the same array.
 240         create_pack = false;
 241       } else {
 242         // Allow independent (different type) unaligned memory operations
 243         // if HW supports them.
 244         if (!Matcher::misaligned_vectors_ok()) {
 245           create_pack = false;
 246         } else {
 247           // Check if packs of the same memory type but
 248           // with a different alignment were created before.
 249           for (uint i = 0; i < align_to_refs.size(); i++) {
 250             MemNode* mr = align_to_refs.at(i)->as_Mem();
 251             if (same_velt_type(mr, mem_ref) &&
 252                 memory_alignment(mr, iv_adjustment) != 0)
 253               create_pack = false;
 254           }
 255         }
 256       }
 257     }
 258     if (create_pack) {
 259       for (uint i = 0; i < memops.size(); i++) {
 260         Node* s1 = memops.at(i);
 261         int align = alignment(s1);
 262         if (align == top_align) continue;
 263         for (uint j = 0; j < memops.size(); j++) {
 264           Node* s2 = memops.at(j);
 265           if (alignment(s2) == top_align) continue;
 266           if (s1 != s2 && are_adjacent_refs(s1, s2)) {
 267             if (stmts_can_pack(s1, s2, align)) {
 268               Node_List* pair = new Node_List();
 269               pair->push(s1);
 270               pair->push(s2);
 271               _packset.append(pair);
 272             }
 273           }
 274         }
 275       }
 276     } else { // Don't create unaligned pack
 277       // First, remove remaining memory ops of the same type from the list.
 278       for (int i = memops.size() - 1; i >= 0; i--) {
 279         MemNode* s = memops.at(i)->as_Mem();
 280         if (same_velt_type(s, mem_ref)) {
 281           memops.remove(i);
 282         }
 283       }
 284 
 285       // Second, remove already constructed packs of the same type.
 286       for (int i = _packset.length() - 1; i >= 0; i--) {
 287         Node_List* p = _packset.at(i);
 288         MemNode* s = p->at(0)->as_Mem();
 289         if (same_velt_type(s, mem_ref)) {
 290           remove_pack_at(i);
 291         }
 292       }
 293 
 294       // If needed find the best memory reference for loop alignment again.
 295       if (same_velt_type(mem_ref, best_align_to_mem_ref)) {
 296         // Put memory ops from remaining packs back on memops list for
 297         // the best alignment search.
 298         uint orig_msize = memops.size();
 299         for (int i = 0; i < _packset.length(); i++) {
 300           Node_List* p = _packset.at(i);
 301           MemNode* s = p->at(0)->as_Mem();
 302           assert(!same_velt_type(s, mem_ref), "sanity");
 303           memops.push(s);
 304         }
 305         MemNode* best_align_to_mem_ref = find_align_to_ref(memops);
 306         if (best_align_to_mem_ref == NULL) break;
 307         best_iv_adjustment = get_iv_adjustment(best_align_to_mem_ref);
 308         // Restore list.
 309         while (memops.size() > orig_msize)
 310           (void)memops.pop();
 311       }
 312     } // unaligned memory accesses
 313 
 314     // Remove used mem nodes.
 315     for (int i = memops.size() - 1; i >= 0; i--) {
 316       MemNode* m = memops.at(i)->as_Mem();
 317       if (alignment(m) != top_align) {
 318         memops.remove(i);
 319       }
 320     }
 321 
 322   } // while (memops.size() != 0
 323   set_align_to_ref(best_align_to_mem_ref);
 324 
 325 #ifndef PRODUCT
 326   if (TraceSuperWord) {
 327     tty->print_cr("\nAfter find_adjacent_refs");
 328     print_packset();
 329   }
 330 #endif
 331 }
 332 
 333 //------------------------------find_align_to_ref---------------------------
 334 // Find a memory reference to align the loop induction variable to.
 335 // Looks first at stores then at loads, looking for a memory reference
 336 // with the largest number of references similar to it.
 337 MemNode* SuperWord::find_align_to_ref(Node_List &memops) {
 338   GrowableArray<int> cmp_ct(arena(), memops.size(), memops.size(), 0);
 339 
 340   // Count number of comparable memory ops
 341   for (uint i = 0; i < memops.size(); i++) {
 342     MemNode* s1 = memops.at(i)->as_Mem();
 343     SWPointer p1(s1, this);
 344     // Discard if pre loop can't align this reference
 345     if (!ref_is_alignable(p1)) {
 346       *cmp_ct.adr_at(i) = 0;
 347       continue;
 348     }
 349     for (uint j = i+1; j < memops.size(); j++) {
 350       MemNode* s2 = memops.at(j)->as_Mem();
 351       if (isomorphic(s1, s2)) {
 352         SWPointer p2(s2, this);
 353         if (p1.comparable(p2)) {
 354           (*cmp_ct.adr_at(i))++;
 355           (*cmp_ct.adr_at(j))++;
 356         }
 357       }
 358     }
 359   }
 360 
 361   // Find Store (or Load) with the greatest number of "comparable" references,
 362   // biggest vector size, smallest data size and smallest iv offset.
 363   int max_ct        = 0;
 364   int max_vw        = 0;
 365   int max_idx       = -1;
 366   int min_size      = max_jint;
 367   int min_iv_offset = max_jint;
 368   for (uint j = 0; j < memops.size(); j++) {
 369     MemNode* s = memops.at(j)->as_Mem();
 370     if (s->is_Store()) {
 371       int vw = vector_width_in_bytes(s);
 372       assert(vw > 1, "sanity");
 373       SWPointer p(s, this);
 374       if (cmp_ct.at(j) >  max_ct ||
 375           cmp_ct.at(j) == max_ct &&
 376             (vw >  max_vw ||
 377              vw == max_vw &&
 378               (data_size(s) <  min_size ||
 379                data_size(s) == min_size &&
 380                  (p.offset_in_bytes() < min_iv_offset)))) {
 381         max_ct = cmp_ct.at(j);
 382         max_vw = vw;
 383         max_idx = j;
 384         min_size = data_size(s);
 385         min_iv_offset = p.offset_in_bytes();
 386       }
 387     }
 388   }
 389   // If no stores, look at loads
 390   if (max_ct == 0) {
 391     for (uint j = 0; j < memops.size(); j++) {
 392       MemNode* s = memops.at(j)->as_Mem();
 393       if (s->is_Load()) {
 394         int vw = vector_width_in_bytes(s);
 395         assert(vw > 1, "sanity");
 396         SWPointer p(s, this);
 397         if (cmp_ct.at(j) >  max_ct ||
 398             cmp_ct.at(j) == max_ct &&
 399               (vw >  max_vw ||
 400                vw == max_vw &&
 401                 (data_size(s) <  min_size ||
 402                  data_size(s) == min_size &&
 403                    (p.offset_in_bytes() < min_iv_offset)))) {
 404           max_ct = cmp_ct.at(j);
 405           max_vw = vw;
 406           max_idx = j;
 407           min_size = data_size(s);
 408           min_iv_offset = p.offset_in_bytes();
 409         }
 410       }
 411     }
 412   }
 413 
 414 #ifdef ASSERT
 415   if (TraceSuperWord && Verbose) {
 416     tty->print_cr("\nVector memops after find_align_to_refs");
 417     for (uint i = 0; i < memops.size(); i++) {
 418       MemNode* s = memops.at(i)->as_Mem();
 419       s->dump();
 420     }
 421   }
 422 #endif
 423 
 424   if (max_ct > 0) {
 425 #ifdef ASSERT
 426     if (TraceSuperWord) {
 427       tty->print("\nVector align to node: ");
 428       memops.at(max_idx)->as_Mem()->dump();
 429     }
 430 #endif
 431     return memops.at(max_idx)->as_Mem();
 432   }
 433   return NULL;
 434 }
 435 
 436 //------------------------------ref_is_alignable---------------------------
 437 // Can the preloop align the reference to position zero in the vector?
 438 bool SuperWord::ref_is_alignable(SWPointer& p) {
 439   if (!p.has_iv()) {
 440     return true;   // no induction variable
 441   }
 442   CountedLoopEndNode* pre_end = get_pre_loop_end(lp()->as_CountedLoop());
 443   assert(pre_end->stride_is_con(), "pre loop stride is constant");
 444   int preloop_stride = pre_end->stride_con();
 445 
 446   int span = preloop_stride * p.scale_in_bytes();
 447 
 448   // Stride one accesses are alignable.
 449   if (ABS(span) == p.memory_size())
 450     return true;
 451 
 452   // If initial offset from start of object is computable,
 453   // compute alignment within the vector.
 454   int vw = vector_width_in_bytes(p.mem());
 455   assert(vw > 1, "sanity");
 456   if (vw % span == 0) {
 457     Node* init_nd = pre_end->init_trip();
 458     if (init_nd->is_Con() && p.invar() == NULL) {
 459       int init = init_nd->bottom_type()->is_int()->get_con();
 460 
 461       int init_offset = init * p.scale_in_bytes() + p.offset_in_bytes();
 462       assert(init_offset >= 0, "positive offset from object start");
 463 
 464       if (span > 0) {
 465         return (vw - (init_offset % vw)) % span == 0;
 466       } else {
 467         assert(span < 0, "nonzero stride * scale");
 468         return (init_offset % vw) % -span == 0;
 469       }
 470     }
 471   }
 472   return false;
 473 }
 474 
 475 //---------------------------get_iv_adjustment---------------------------
 476 // Calculate loop's iv adjustment for this memory ops.
 477 int SuperWord::get_iv_adjustment(MemNode* mem_ref) {
 478   SWPointer align_to_ref_p(mem_ref, this);
 479   int offset = align_to_ref_p.offset_in_bytes();
 480   int scale  = align_to_ref_p.scale_in_bytes();
 481   int vw       = vector_width_in_bytes(mem_ref);
 482   assert(vw > 1, "sanity");
 483   int stride_sign   = (scale * iv_stride()) > 0 ? 1 : -1;
 484   int iv_adjustment = (stride_sign * vw - (offset % vw)) % vw;
 485 
 486 #ifndef PRODUCT
 487   if (TraceSuperWord)
 488     tty->print_cr("\noffset = %d iv_adjust = %d elt_size = %d scale = %d iv_stride = %d vect_size %d",
 489                   offset, iv_adjustment, align_to_ref_p.memory_size(), scale, iv_stride(), vw);
 490 #endif
 491   return iv_adjustment;
 492 }
 493 
 494 //---------------------------dependence_graph---------------------------
 495 // Construct dependency graph.
 496 // Add dependence edges to load/store nodes for memory dependence
 497 //    A.out()->DependNode.in(1) and DependNode.out()->B.prec(x)
 498 void SuperWord::dependence_graph() {
 499   // First, assign a dependence node to each memory node
 500   for (int i = 0; i < _block.length(); i++ ) {
 501     Node *n = _block.at(i);
 502     if (n->is_Mem() || n->is_Phi() && n->bottom_type() == Type::MEMORY) {
 503       _dg.make_node(n);
 504     }
 505   }
 506 
 507   // For each memory slice, create the dependences
 508   for (int i = 0; i < _mem_slice_head.length(); i++) {
 509     Node* n      = _mem_slice_head.at(i);
 510     Node* n_tail = _mem_slice_tail.at(i);
 511 
 512     // Get slice in predecessor order (last is first)
 513     mem_slice_preds(n_tail, n, _nlist);
 514 
 515     // Make the slice dependent on the root
 516     DepMem* slice = _dg.dep(n);
 517     _dg.make_edge(_dg.root(), slice);
 518 
 519     // Create a sink for the slice
 520     DepMem* slice_sink = _dg.make_node(NULL);
 521     _dg.make_edge(slice_sink, _dg.tail());
 522 
 523     // Now visit each pair of memory ops, creating the edges
 524     for (int j = _nlist.length() - 1; j >= 0 ; j--) {
 525       Node* s1 = _nlist.at(j);
 526 
 527       // If no dependency yet, use slice
 528       if (_dg.dep(s1)->in_cnt() == 0) {
 529         _dg.make_edge(slice, s1);
 530       }
 531       SWPointer p1(s1->as_Mem(), this);
 532       bool sink_dependent = true;
 533       for (int k = j - 1; k >= 0; k--) {
 534         Node* s2 = _nlist.at(k);
 535         if (s1->is_Load() && s2->is_Load())
 536           continue;
 537         SWPointer p2(s2->as_Mem(), this);
 538 
 539         int cmp = p1.cmp(p2);
 540         if (SuperWordRTDepCheck &&
 541             p1.base() != p2.base() && p1.valid() && p2.valid()) {
 542           // Create a runtime check to disambiguate
 543           OrderedPair pp(p1.base(), p2.base());
 544           _disjoint_ptrs.append_if_missing(pp);
 545         } else if (!SWPointer::not_equal(cmp)) {
 546           // Possibly same address
 547           _dg.make_edge(s1, s2);
 548           sink_dependent = false;
 549         }
 550       }
 551       if (sink_dependent) {
 552         _dg.make_edge(s1, slice_sink);
 553       }
 554     }
 555 #ifndef PRODUCT
 556     if (TraceSuperWord) {
 557       tty->print_cr("\nDependence graph for slice: %d", n->_idx);
 558       for (int q = 0; q < _nlist.length(); q++) {
 559         _dg.print(_nlist.at(q));
 560       }
 561       tty->cr();
 562     }
 563 #endif
 564     _nlist.clear();
 565   }
 566 
 567 #ifndef PRODUCT
 568   if (TraceSuperWord) {
 569     tty->print_cr("\ndisjoint_ptrs: %s", _disjoint_ptrs.length() > 0 ? "" : "NONE");
 570     for (int r = 0; r < _disjoint_ptrs.length(); r++) {
 571       _disjoint_ptrs.at(r).print();
 572       tty->cr();
 573     }
 574     tty->cr();
 575   }
 576 #endif
 577 }
 578 
 579 //---------------------------mem_slice_preds---------------------------
 580 // Return a memory slice (node list) in predecessor order starting at "start"
 581 void SuperWord::mem_slice_preds(Node* start, Node* stop, GrowableArray<Node*> &preds) {
 582   assert(preds.length() == 0, "start empty");
 583   Node* n = start;
 584   Node* prev = NULL;
 585   while (true) {
 586     assert(in_bb(n), "must be in block");
 587     for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
 588       Node* out = n->fast_out(i);
 589       if (out->is_Load()) {
 590         if (in_bb(out)) {
 591           preds.push(out);
 592         }
 593       } else {
 594         // FIXME
 595         if (out->is_MergeMem() && !in_bb(out)) {
 596           // Either unrolling is causing a memory edge not to disappear,
 597           // or need to run igvn.optimize() again before SLP
 598         } else if (out->is_Phi() && out->bottom_type() == Type::MEMORY && !in_bb(out)) {
 599           // Ditto.  Not sure what else to check further.
 600         } else if (out->Opcode() == Op_StoreCM && out->in(MemNode::OopStore) == n) {
 601           // StoreCM has an input edge used as a precedence edge.
 602           // Maybe an issue when oop stores are vectorized.
 603         } else {
 604           assert(out == prev || prev == NULL, "no branches off of store slice");
 605         }
 606       }
 607     }
 608     if (n == stop) break;
 609     preds.push(n);
 610     prev = n;
 611     n = n->in(MemNode::Memory);
 612   }
 613 }
 614 
 615 //------------------------------stmts_can_pack---------------------------
 616 // Can s1 and s2 be in a pack with s1 immediately preceding s2 and
 617 // s1 aligned at "align"
 618 bool SuperWord::stmts_can_pack(Node* s1, Node* s2, int align) {
 619 
 620   // Do not use superword for non-primitives
 621   BasicType bt1 = velt_basic_type(s1);
 622   BasicType bt2 = velt_basic_type(s2);
 623   if(!is_java_primitive(bt1) || !is_java_primitive(bt2))
 624     return false;
 625   if (Matcher::max_vector_size(bt1) < 2) {
 626     return false; // No vectors for this type
 627   }
 628 
 629   if (isomorphic(s1, s2)) {
 630     if (independent(s1, s2)) {
 631       if (!exists_at(s1, 0) && !exists_at(s2, 1)) {
 632         if (!s1->is_Mem() || are_adjacent_refs(s1, s2)) {
 633           int s1_align = alignment(s1);
 634           int s2_align = alignment(s2);
 635           if (s1_align == top_align || s1_align == align) {
 636             if (s2_align == top_align || s2_align == align + data_size(s1)) {
 637               return true;
 638             }
 639           }
 640         }
 641       }
 642     }
 643   }
 644   return false;
 645 }
 646 
 647 //------------------------------exists_at---------------------------
 648 // Does s exist in a pack at position pos?
 649 bool SuperWord::exists_at(Node* s, uint pos) {
 650   for (int i = 0; i < _packset.length(); i++) {
 651     Node_List* p = _packset.at(i);
 652     if (p->at(pos) == s) {
 653       return true;
 654     }
 655   }
 656   return false;
 657 }
 658 
 659 //------------------------------are_adjacent_refs---------------------------
 660 // Is s1 immediately before s2 in memory?
 661 bool SuperWord::are_adjacent_refs(Node* s1, Node* s2) {
 662   if (!s1->is_Mem() || !s2->is_Mem()) return false;
 663   if (!in_bb(s1)    || !in_bb(s2))    return false;
 664 
 665   // Do not use superword for non-primitives
 666   if (!is_java_primitive(s1->as_Mem()->memory_type()) ||
 667       !is_java_primitive(s2->as_Mem()->memory_type())) {
 668     return false;
 669   }
 670 
 671   // FIXME - co_locate_pack fails on Stores in different mem-slices, so
 672   // only pack memops that are in the same alias set until that's fixed.
 673   if (_phase->C->get_alias_index(s1->as_Mem()->adr_type()) !=
 674       _phase->C->get_alias_index(s2->as_Mem()->adr_type()))
 675     return false;
 676   SWPointer p1(s1->as_Mem(), this);
 677   SWPointer p2(s2->as_Mem(), this);
 678   if (p1.base() != p2.base() || !p1.comparable(p2)) return false;
 679   int diff = p2.offset_in_bytes() - p1.offset_in_bytes();
 680   return diff == data_size(s1);
 681 }
 682 
 683 //------------------------------isomorphic---------------------------
 684 // Are s1 and s2 similar?
 685 bool SuperWord::isomorphic(Node* s1, Node* s2) {
 686   if (s1->Opcode() != s2->Opcode()) return false;
 687   if (s1->req() != s2->req()) return false;
 688   if (s1->in(0) != s2->in(0)) return false;
 689   if (!same_velt_type(s1, s2)) return false;
 690   return true;
 691 }
 692 
 693 //------------------------------independent---------------------------
 694 // Is there no data path from s1 to s2 or s2 to s1?
 695 bool SuperWord::independent(Node* s1, Node* s2) {
 696   //  assert(s1->Opcode() == s2->Opcode(), "check isomorphic first");
 697   int d1 = depth(s1);
 698   int d2 = depth(s2);
 699   if (d1 == d2) return s1 != s2;
 700   Node* deep    = d1 > d2 ? s1 : s2;
 701   Node* shallow = d1 > d2 ? s2 : s1;
 702 
 703   visited_clear();
 704 
 705   return independent_path(shallow, deep);
 706 }
 707 
 708 //------------------------------independent_path------------------------------
 709 // Helper for independent
 710 bool SuperWord::independent_path(Node* shallow, Node* deep, uint dp) {
 711   if (dp >= 1000) return false; // stop deep recursion
 712   visited_set(deep);
 713   int shal_depth = depth(shallow);
 714   assert(shal_depth <= depth(deep), "must be");
 715   for (DepPreds preds(deep, _dg); !preds.done(); preds.next()) {
 716     Node* pred = preds.current();
 717     if (in_bb(pred) && !visited_test(pred)) {
 718       if (shallow == pred) {
 719         return false;
 720       }
 721       if (shal_depth < depth(pred) && !independent_path(shallow, pred, dp+1)) {
 722         return false;
 723       }
 724     }
 725   }
 726   return true;
 727 }
 728 
 729 //------------------------------set_alignment---------------------------
 730 void SuperWord::set_alignment(Node* s1, Node* s2, int align) {
 731   set_alignment(s1, align);
 732   if (align == top_align || align == bottom_align) {
 733     set_alignment(s2, align);
 734   } else {
 735     set_alignment(s2, align + data_size(s1));
 736   }
 737 }
 738 
 739 //------------------------------data_size---------------------------
 740 int SuperWord::data_size(Node* s) {
 741   int bsize = type2aelembytes(velt_basic_type(s));
 742   assert(bsize != 0, "valid size");
 743   return bsize;
 744 }
 745 
 746 //------------------------------extend_packlist---------------------------
 747 // Extend packset by following use->def and def->use links from pack members.
 748 void SuperWord::extend_packlist() {
 749   bool changed;
 750   do {
 751     changed = false;
 752     for (int i = 0; i < _packset.length(); i++) {
 753       Node_List* p = _packset.at(i);
 754       changed |= follow_use_defs(p);
 755       changed |= follow_def_uses(p);
 756     }
 757   } while (changed);
 758 
 759 #ifndef PRODUCT
 760   if (TraceSuperWord) {
 761     tty->print_cr("\nAfter extend_packlist");
 762     print_packset();
 763   }
 764 #endif
 765 }
 766 
 767 //------------------------------follow_use_defs---------------------------
 768 // Extend the packset by visiting operand definitions of nodes in pack p
 769 bool SuperWord::follow_use_defs(Node_List* p) {
 770   assert(p->size() == 2, "just checking");
 771   Node* s1 = p->at(0);
 772   Node* s2 = p->at(1);
 773   assert(s1->req() == s2->req(), "just checking");
 774   assert(alignment(s1) + data_size(s1) == alignment(s2), "just checking");
 775 
 776   if (s1->is_Load()) return false;
 777 
 778   int align = alignment(s1);
 779   bool changed = false;
 780   int start = s1->is_Store() ? MemNode::ValueIn   : 1;
 781   int end   = s1->is_Store() ? MemNode::ValueIn+1 : s1->req();
 782   for (int j = start; j < end; j++) {
 783     Node* t1 = s1->in(j);
 784     Node* t2 = s2->in(j);
 785     if (!in_bb(t1) || !in_bb(t2))
 786       continue;
 787     if (stmts_can_pack(t1, t2, align)) {
 788       if (est_savings(t1, t2) >= 0) {
 789         Node_List* pair = new Node_List();
 790         pair->push(t1);
 791         pair->push(t2);
 792         _packset.append(pair);
 793         set_alignment(t1, t2, align);
 794         changed = true;
 795       }
 796     }
 797   }
 798   return changed;
 799 }
 800 
 801 //------------------------------follow_def_uses---------------------------
 802 // Extend the packset by visiting uses of nodes in pack p
 803 bool SuperWord::follow_def_uses(Node_List* p) {
 804   bool changed = false;
 805   Node* s1 = p->at(0);
 806   Node* s2 = p->at(1);
 807   assert(p->size() == 2, "just checking");
 808   assert(s1->req() == s2->req(), "just checking");
 809   assert(alignment(s1) + data_size(s1) == alignment(s2), "just checking");
 810 
 811   if (s1->is_Store()) return false;
 812 
 813   int align = alignment(s1);
 814   int savings = -1;
 815   Node* u1 = NULL;
 816   Node* u2 = NULL;
 817   for (DUIterator_Fast imax, i = s1->fast_outs(imax); i < imax; i++) {
 818     Node* t1 = s1->fast_out(i);
 819     if (!in_bb(t1)) continue;
 820     for (DUIterator_Fast jmax, j = s2->fast_outs(jmax); j < jmax; j++) {
 821       Node* t2 = s2->fast_out(j);
 822       if (!in_bb(t2)) continue;
 823       if (!opnd_positions_match(s1, t1, s2, t2))
 824         continue;
 825       if (stmts_can_pack(t1, t2, align)) {
 826         int my_savings = est_savings(t1, t2);
 827         if (my_savings > savings) {
 828           savings = my_savings;
 829           u1 = t1;
 830           u2 = t2;
 831         }
 832       }
 833     }
 834   }
 835   if (savings >= 0) {
 836     Node_List* pair = new Node_List();
 837     pair->push(u1);
 838     pair->push(u2);
 839     _packset.append(pair);
 840     set_alignment(u1, u2, align);
 841     changed = true;
 842   }
 843   return changed;
 844 }
 845 
 846 //---------------------------opnd_positions_match-------------------------
 847 // Is the use of d1 in u1 at the same operand position as d2 in u2?
 848 bool SuperWord::opnd_positions_match(Node* d1, Node* u1, Node* d2, Node* u2) {
 849   uint ct = u1->req();
 850   if (ct != u2->req()) return false;
 851   uint i1 = 0;
 852   uint i2 = 0;
 853   do {
 854     for (i1++; i1 < ct; i1++) if (u1->in(i1) == d1) break;
 855     for (i2++; i2 < ct; i2++) if (u2->in(i2) == d2) break;
 856     if (i1 != i2) {
 857       if ((i1 == (3-i2)) && (u2->is_Add() || u2->is_Mul())) {
 858         // Further analysis relies on operands position matching.
 859         u2->swap_edges(i1, i2);
 860       } else {
 861         return false;
 862       }
 863     }
 864   } while (i1 < ct);
 865   return true;
 866 }
 867 
 868 //------------------------------est_savings---------------------------
 869 // Estimate the savings from executing s1 and s2 as a pack
 870 int SuperWord::est_savings(Node* s1, Node* s2) {
 871   int save_in = 2 - 1; // 2 operations per instruction in packed form
 872 
 873   // inputs
 874   for (uint i = 1; i < s1->req(); i++) {
 875     Node* x1 = s1->in(i);
 876     Node* x2 = s2->in(i);
 877     if (x1 != x2) {
 878       if (are_adjacent_refs(x1, x2)) {
 879         save_in += adjacent_profit(x1, x2);
 880       } else if (!in_packset(x1, x2)) {
 881         save_in -= pack_cost(2);
 882       } else {
 883         save_in += unpack_cost(2);
 884       }
 885     }
 886   }
 887 
 888   // uses of result
 889   uint ct = 0;
 890   int save_use = 0;
 891   for (DUIterator_Fast imax, i = s1->fast_outs(imax); i < imax; i++) {
 892     Node* s1_use = s1->fast_out(i);
 893     for (int j = 0; j < _packset.length(); j++) {
 894       Node_List* p = _packset.at(j);
 895       if (p->at(0) == s1_use) {
 896         for (DUIterator_Fast kmax, k = s2->fast_outs(kmax); k < kmax; k++) {
 897           Node* s2_use = s2->fast_out(k);
 898           if (p->at(p->size()-1) == s2_use) {
 899             ct++;
 900             if (are_adjacent_refs(s1_use, s2_use)) {
 901               save_use += adjacent_profit(s1_use, s2_use);
 902             }
 903           }
 904         }
 905       }
 906     }
 907   }
 908 
 909   if (ct < s1->outcnt()) save_use += unpack_cost(1);
 910   if (ct < s2->outcnt()) save_use += unpack_cost(1);
 911 
 912   return MAX2(save_in, save_use);
 913 }
 914 
 915 //------------------------------costs---------------------------
 916 int SuperWord::adjacent_profit(Node* s1, Node* s2) { return 2; }
 917 int SuperWord::pack_cost(int ct)   { return ct; }
 918 int SuperWord::unpack_cost(int ct) { return ct; }
 919 
 920 //------------------------------combine_packs---------------------------
 921 // Combine packs A and B with A.last == B.first into A.first..,A.last,B.second,..B.last
 922 void SuperWord::combine_packs() {
 923   bool changed = true;
 924   // Combine packs regardless max vector size.
 925   while (changed) {
 926     changed = false;
 927     for (int i = 0; i < _packset.length(); i++) {
 928       Node_List* p1 = _packset.at(i);
 929       if (p1 == NULL) continue;
 930       for (int j = 0; j < _packset.length(); j++) {
 931         Node_List* p2 = _packset.at(j);
 932         if (p2 == NULL) continue;
 933         if (i == j) continue;
 934         if (p1->at(p1->size()-1) == p2->at(0)) {
 935           for (uint k = 1; k < p2->size(); k++) {
 936             p1->push(p2->at(k));
 937           }
 938           _packset.at_put(j, NULL);
 939           changed = true;
 940         }
 941       }
 942     }
 943   }
 944 
 945   // Split packs which have size greater then max vector size.
 946   for (int i = 0; i < _packset.length(); i++) {
 947     Node_List* p1 = _packset.at(i);
 948     if (p1 != NULL) {
 949       BasicType bt = velt_basic_type(p1->at(0));
 950       uint max_vlen = Matcher::max_vector_size(bt); // Max elements in vector
 951       assert(is_power_of_2(max_vlen), "sanity");
 952       uint psize = p1->size();
 953       if (!is_power_of_2(psize)) {
 954         // Skip pack which can't be vector.
 955         // case1: for(...) { a[i] = i; }    elements values are different (i+x)
 956         // case2: for(...) { a[i] = b[i+1]; }  can't align both, load and store
 957         _packset.at_put(i, NULL);
 958         continue;
 959       }
 960       if (psize > max_vlen) {
 961         Node_List* pack = new Node_List();
 962         for (uint j = 0; j < psize; j++) {
 963           pack->push(p1->at(j));
 964           if (pack->size() >= max_vlen) {
 965             assert(is_power_of_2(pack->size()), "sanity");
 966             _packset.append(pack);
 967             pack = new Node_List();
 968           }
 969         }
 970         _packset.at_put(i, NULL);
 971       }
 972     }
 973   }
 974 
 975   // Compress list.
 976   for (int i = _packset.length() - 1; i >= 0; i--) {
 977     Node_List* p1 = _packset.at(i);
 978     if (p1 == NULL) {
 979       _packset.remove_at(i);
 980     }
 981   }
 982 
 983 #ifndef PRODUCT
 984   if (TraceSuperWord) {
 985     tty->print_cr("\nAfter combine_packs");
 986     print_packset();
 987   }
 988 #endif
 989 }
 990 
 991 //-----------------------------construct_my_pack_map--------------------------
 992 // Construct the map from nodes to packs.  Only valid after the
 993 // point where a node is only in one pack (after combine_packs).
 994 void SuperWord::construct_my_pack_map() {
 995   Node_List* rslt = NULL;
 996   for (int i = 0; i < _packset.length(); i++) {
 997     Node_List* p = _packset.at(i);
 998     for (uint j = 0; j < p->size(); j++) {
 999       Node* s = p->at(j);
1000       assert(my_pack(s) == NULL, "only in one pack");
1001       set_my_pack(s, p);
1002     }
1003   }
1004 }
1005 
1006 //------------------------------filter_packs---------------------------
1007 // Remove packs that are not implemented or not profitable.
1008 void SuperWord::filter_packs() {
1009 
1010   // Remove packs that are not implemented
1011   for (int i = _packset.length() - 1; i >= 0; i--) {
1012     Node_List* pk = _packset.at(i);
1013     bool impl = implemented(pk);
1014     if (!impl) {
1015 #ifndef PRODUCT
1016       if (TraceSuperWord && Verbose) {
1017         tty->print_cr("Unimplemented");
1018         pk->at(0)->dump();
1019       }
1020 #endif
1021       remove_pack_at(i);
1022     }
1023   }
1024 
1025   // Remove packs that are not profitable
1026   bool changed;
1027   do {
1028     changed = false;
1029     for (int i = _packset.length() - 1; i >= 0; i--) {
1030       Node_List* pk = _packset.at(i);
1031       bool prof = profitable(pk);
1032       if (!prof) {
1033 #ifndef PRODUCT
1034         if (TraceSuperWord && Verbose) {
1035           tty->print_cr("Unprofitable");
1036           pk->at(0)->dump();
1037         }
1038 #endif
1039         remove_pack_at(i);
1040         changed = true;
1041       }
1042     }
1043   } while (changed);
1044 
1045 #ifndef PRODUCT
1046   if (TraceSuperWord) {
1047     tty->print_cr("\nAfter filter_packs");
1048     print_packset();
1049     tty->cr();
1050   }
1051 #endif
1052 }
1053 
1054 //------------------------------implemented---------------------------
1055 // Can code be generated for pack p?
1056 bool SuperWord::implemented(Node_List* p) {
1057   Node* p0 = p->at(0);
1058   return VectorNode::implemented(p0->Opcode(), p->size(), velt_basic_type(p0));
1059 }
1060 
1061 //------------------------------profitable---------------------------
1062 // For pack p, are all operands and all uses (with in the block) vector?
1063 bool SuperWord::profitable(Node_List* p) {
1064   Node* p0 = p->at(0);
1065   uint start, end;
1066   vector_opd_range(p0, &start, &end);
1067 
1068   // Return false if some input is not vector and inside block
1069   for (uint i = start; i < end; i++) {
1070     if (!is_vector_use(p0, i)) {
1071       // For now, return false if not scalar promotion case (inputs are the same.)
1072       // Later, implement PackNode and allow differing, non-vector inputs
1073       // (maybe just the ones from outside the block.)
1074       Node* p0_def = p0->in(i);
1075       for (uint j = 1; j < p->size(); j++) {
1076         Node* use = p->at(j);
1077         Node* def = use->in(i);
1078         if (p0_def != def)
1079           return false;
1080       }
1081     }
1082   }
1083   if (!p0->is_Store()) {
1084     // For now, return false if not all uses are vector.
1085     // Later, implement ExtractNode and allow non-vector uses (maybe
1086     // just the ones outside the block.)
1087     for (uint i = 0; i < p->size(); i++) {
1088       Node* def = p->at(i);
1089       for (DUIterator_Fast jmax, j = def->fast_outs(jmax); j < jmax; j++) {
1090         Node* use = def->fast_out(j);
1091         for (uint k = 0; k < use->req(); k++) {
1092           Node* n = use->in(k);
1093           if (def == n) {
1094             if (!is_vector_use(use, k)) {
1095               return false;
1096             }
1097           }
1098         }
1099       }
1100     }
1101   }
1102   return true;
1103 }
1104 
1105 //------------------------------schedule---------------------------
1106 // Adjust the memory graph for the packed operations
1107 void SuperWord::schedule() {
1108 
1109   // Co-locate in the memory graph the members of each memory pack
1110   for (int i = 0; i < _packset.length(); i++) {
1111     co_locate_pack(_packset.at(i));
1112   }
1113 }
1114 
1115 //-------------------------------remove_and_insert-------------------
1116 // Remove "current" from its current position in the memory graph and insert
1117 // it after the appropriate insertion point (lip or uip).
1118 void SuperWord::remove_and_insert(MemNode *current, MemNode *prev, MemNode *lip,
1119                                   Node *uip, Unique_Node_List &sched_before) {
1120   Node* my_mem = current->in(MemNode::Memory);
1121   bool sched_up = sched_before.member(current);
1122 
1123   // remove current_store from its current position in the memmory graph
1124   for (DUIterator i = current->outs(); current->has_out(i); i++) {
1125     Node* use = current->out(i);
1126     if (use->is_Mem()) {
1127       assert(use->in(MemNode::Memory) == current, "must be");
1128       if (use == prev) { // connect prev to my_mem
1129           _igvn.replace_input_of(use, MemNode::Memory, my_mem);
1130           --i; //deleted this edge; rescan position
1131       } else if (sched_before.member(use)) {
1132         if (!sched_up) { // Will be moved together with current
1133           _igvn.replace_input_of(use, MemNode::Memory, uip);
1134           --i; //deleted this edge; rescan position
1135         }
1136       } else {
1137         if (sched_up) { // Will be moved together with current
1138           _igvn.replace_input_of(use, MemNode::Memory, lip);
1139           --i; //deleted this edge; rescan position
1140         }
1141       }
1142     }
1143   }
1144 
1145   Node *insert_pt =  sched_up ?  uip : lip;
1146 
1147   // all uses of insert_pt's memory state should use current's instead
1148   for (DUIterator i = insert_pt->outs(); insert_pt->has_out(i); i++) {
1149     Node* use = insert_pt->out(i);
1150     if (use->is_Mem()) {
1151       assert(use->in(MemNode::Memory) == insert_pt, "must be");
1152       _igvn.replace_input_of(use, MemNode::Memory, current);
1153       --i; //deleted this edge; rescan position
1154     } else if (!sched_up && use->is_Phi() && use->bottom_type() == Type::MEMORY) {
1155       uint pos; //lip (lower insert point) must be the last one in the memory slice
1156       for (pos=1; pos < use->req(); pos++) {
1157         if (use->in(pos) == insert_pt) break;
1158       }
1159       _igvn.replace_input_of(use, pos, current);
1160       --i;
1161     }
1162   }
1163 
1164   //connect current to insert_pt
1165   _igvn.replace_input_of(current, MemNode::Memory, insert_pt);
1166 }
1167 
1168 //------------------------------co_locate_pack----------------------------------
1169 // To schedule a store pack, we need to move any sandwiched memory ops either before
1170 // or after the pack, based upon dependence information:
1171 // (1) If any store in the pack depends on the sandwiched memory op, the
1172 //     sandwiched memory op must be scheduled BEFORE the pack;
1173 // (2) If a sandwiched memory op depends on any store in the pack, the
1174 //     sandwiched memory op must be scheduled AFTER the pack;
1175 // (3) If a sandwiched memory op (say, memA) depends on another sandwiched
1176 //     memory op (say memB), memB must be scheduled before memA. So, if memA is
1177 //     scheduled before the pack, memB must also be scheduled before the pack;
1178 // (4) If there is no dependence restriction for a sandwiched memory op, we simply
1179 //     schedule this store AFTER the pack
1180 // (5) We know there is no dependence cycle, so there in no other case;
1181 // (6) Finally, all memory ops in another single pack should be moved in the same direction.
1182 //
1183 // To schedule a load pack, we use the memory state of either the first or the last load in
1184 // the pack, based on the dependence constraint.
1185 void SuperWord::co_locate_pack(Node_List* pk) {
1186   if (pk->at(0)->is_Store()) {
1187     MemNode* first     = executed_first(pk)->as_Mem();
1188     MemNode* last      = executed_last(pk)->as_Mem();
1189     Unique_Node_List schedule_before_pack;
1190     Unique_Node_List memops;
1191 
1192     MemNode* current   = last->in(MemNode::Memory)->as_Mem();
1193     MemNode* previous  = last;
1194     while (true) {
1195       assert(in_bb(current), "stay in block");
1196       memops.push(previous);
1197       for (DUIterator i = current->outs(); current->has_out(i); i++) {
1198         Node* use = current->out(i);
1199         if (use->is_Mem() && use != previous)
1200           memops.push(use);
1201       }
1202       if (current == first) break;
1203       previous = current;
1204       current  = current->in(MemNode::Memory)->as_Mem();
1205     }
1206 
1207     // determine which memory operations should be scheduled before the pack
1208     for (uint i = 1; i < memops.size(); i++) {
1209       Node *s1 = memops.at(i);
1210       if (!in_pack(s1, pk) && !schedule_before_pack.member(s1)) {
1211         for (uint j = 0; j< i; j++) {
1212           Node *s2 = memops.at(j);
1213           if (!independent(s1, s2)) {
1214             if (in_pack(s2, pk) || schedule_before_pack.member(s2)) {
1215               schedule_before_pack.push(s1); // s1 must be scheduled before
1216               Node_List* mem_pk = my_pack(s1);
1217               if (mem_pk != NULL) {
1218                 for (uint ii = 0; ii < mem_pk->size(); ii++) {
1219                   Node* s = mem_pk->at(ii);  // follow partner
1220                   if (memops.member(s) && !schedule_before_pack.member(s))
1221                     schedule_before_pack.push(s);
1222                 }
1223               }
1224               break;
1225             }
1226           }
1227         }
1228       }
1229     }
1230 
1231     Node*    upper_insert_pt = first->in(MemNode::Memory);
1232     // Following code moves loads connected to upper_insert_pt below aliased stores.
1233     // Collect such loads here and reconnect them back to upper_insert_pt later.
1234     memops.clear();
1235     for (DUIterator i = upper_insert_pt->outs(); upper_insert_pt->has_out(i); i++) {
1236       Node* use = upper_insert_pt->out(i);
1237       if (!use->is_Store())
1238         memops.push(use);
1239     }
1240 
1241     MemNode* lower_insert_pt = last;
1242     previous                 = last; //previous store in pk
1243     current                  = last->in(MemNode::Memory)->as_Mem();
1244 
1245     // start scheduling from "last" to "first"
1246     while (true) {
1247       assert(in_bb(current), "stay in block");
1248       assert(in_pack(previous, pk), "previous stays in pack");
1249       Node* my_mem = current->in(MemNode::Memory);
1250 
1251       if (in_pack(current, pk)) {
1252         // Forward users of my memory state (except "previous) to my input memory state
1253         for (DUIterator i = current->outs(); current->has_out(i); i++) {
1254           Node* use = current->out(i);
1255           if (use->is_Mem() && use != previous) {
1256             assert(use->in(MemNode::Memory) == current, "must be");
1257             if (schedule_before_pack.member(use)) {
1258               _igvn.replace_input_of(use, MemNode::Memory, upper_insert_pt);
1259             } else {
1260               _igvn.replace_input_of(use, MemNode::Memory, lower_insert_pt);
1261             }
1262             --i; // deleted this edge; rescan position
1263           }
1264         }
1265         previous = current;
1266       } else { // !in_pack(current, pk) ==> a sandwiched store
1267         remove_and_insert(current, previous, lower_insert_pt, upper_insert_pt, schedule_before_pack);
1268       }
1269 
1270       if (current == first) break;
1271       current = my_mem->as_Mem();
1272     } // end while
1273 
1274     // Reconnect loads back to upper_insert_pt.
1275     for (uint i = 0; i < memops.size(); i++) {
1276       Node *ld = memops.at(i);
1277       if (ld->in(MemNode::Memory) != upper_insert_pt) {
1278         _igvn.replace_input_of(ld, MemNode::Memory, upper_insert_pt);
1279       }
1280     }
1281   } else if (pk->at(0)->is_Load()) { //load
1282     // all loads in the pack should have the same memory state. By default,
1283     // we use the memory state of the last load. However, if any load could
1284     // not be moved down due to the dependence constraint, we use the memory
1285     // state of the first load.
1286     Node* last_mem  = executed_last(pk)->in(MemNode::Memory);
1287     Node* first_mem = executed_first(pk)->in(MemNode::Memory);
1288     bool schedule_last = true;
1289     for (uint i = 0; i < pk->size(); i++) {
1290       Node* ld = pk->at(i);
1291       for (Node* current = last_mem; current != ld->in(MemNode::Memory);
1292            current=current->in(MemNode::Memory)) {
1293         assert(current != first_mem, "corrupted memory graph");
1294         if(current->is_Mem() && !independent(current, ld)){
1295           schedule_last = false; // a later store depends on this load
1296           break;
1297         }
1298       }
1299     }
1300 
1301     Node* mem_input = schedule_last ? last_mem : first_mem;
1302     _igvn.hash_delete(mem_input);
1303     // Give each load the same memory state
1304     for (uint i = 0; i < pk->size(); i++) {
1305       LoadNode* ld = pk->at(i)->as_Load();
1306       _igvn.replace_input_of(ld, MemNode::Memory, mem_input);
1307     }
1308   }
1309 }
1310 
1311 //------------------------------output---------------------------
1312 // Convert packs into vector node operations
1313 void SuperWord::output() {
1314   if (_packset.length() == 0) return;
1315 
1316 #ifndef PRODUCT
1317   if (TraceLoopOpts) {
1318     tty->print("SuperWord    ");
1319     lpt()->dump_head();
1320   }
1321 #endif
1322 
1323   // MUST ENSURE main loop's initial value is properly aligned:
1324   //  (iv_initial_value + min_iv_offset) % vector_width_in_bytes() == 0
1325 
1326   align_initial_loop_index(align_to_ref());
1327 
1328   // Insert extract (unpack) operations for scalar uses
1329   for (int i = 0; i < _packset.length(); i++) {
1330     insert_extracts(_packset.at(i));
1331   }
1332 
1333   for (int i = 0; i < _block.length(); i++) {
1334     Node* n = _block.at(i);
1335     Node_List* p = my_pack(n);
1336     if (p && n == executed_last(p)) {
1337       uint vlen = p->size();
1338       Node* vn = NULL;
1339       Node* low_adr = p->at(0);
1340       Node* first   = executed_first(p);
1341       int   opc = n->Opcode();
1342       if (n->is_Load()) {
1343         Node* ctl = n->in(MemNode::Control);
1344         Node* mem = first->in(MemNode::Memory);
1345         Node* adr = low_adr->in(MemNode::Address);
1346         const TypePtr* atyp = n->adr_type();
1347         vn = LoadVectorNode::make(_phase->C, opc, ctl, mem, adr, atyp, vlen, velt_basic_type(n));
1348       } else if (n->is_Store()) {
1349         // Promote value to be stored to vector
1350         Node* val = vector_opd(p, MemNode::ValueIn);
1351         Node* ctl = n->in(MemNode::Control);
1352         Node* mem = first->in(MemNode::Memory);
1353         Node* adr = low_adr->in(MemNode::Address);
1354         const TypePtr* atyp = n->adr_type();
1355         vn = StoreVectorNode::make(_phase->C, opc, ctl, mem, adr, atyp, val, vlen);
1356       } else if (n->req() == 3) {
1357         // Promote operands to vector
1358         Node* in1 = vector_opd(p, 1);
1359         Node* in2 = vector_opd(p, 2);
1360         vn = VectorNode::make(_phase->C, opc, in1, in2, vlen, velt_basic_type(n));
1361       } else {
1362         ShouldNotReachHere();
1363       }
1364       assert(vn != NULL, "sanity");
1365       _phase->_igvn.register_new_node_with_optimizer(vn);
1366       _phase->set_ctrl(vn, _phase->get_ctrl(p->at(0)));
1367       for (uint j = 0; j < p->size(); j++) {
1368         Node* pm = p->at(j);
1369         _igvn.replace_node(pm, vn);
1370       }
1371       _igvn._worklist.push(vn);
1372 #ifdef ASSERT
1373       if (TraceNewVectors) {
1374         tty->print("new Vector node: ");
1375         vn->dump();
1376       }
1377 #endif
1378     }
1379   }
1380 }
1381 
1382 //------------------------------vector_opd---------------------------
1383 // Create a vector operand for the nodes in pack p for operand: in(opd_idx)
1384 Node* SuperWord::vector_opd(Node_List* p, int opd_idx) {
1385   Node* p0 = p->at(0);
1386   uint vlen = p->size();
1387   Node* opd = p0->in(opd_idx);
1388 
1389   bool same_opd = true;
1390   for (uint i = 1; i < vlen; i++) {
1391     Node* pi = p->at(i);
1392     Node* in = pi->in(opd_idx);
1393     if (opd != in) {
1394       same_opd = false;
1395       break;
1396     }
1397   }
1398 
1399   if (same_opd) {
1400     if (opd->is_Vector() || opd->is_LoadVector()) {
1401       return opd; // input is matching vector
1402     }
1403     assert(!opd->is_StoreVector(), "such vector is not expected here");
1404     // Convert scalar input to vector with the same number of elements as
1405     // p0's vector. Use p0's type because size of operand's container in
1406     // vector should match p0's size regardless operand's size.
1407     const Type* p0_t = velt_type(p0);
1408     VectorNode* vn = VectorNode::scalar2vector(_phase->C, opd, vlen, p0_t);
1409 
1410     _phase->_igvn.register_new_node_with_optimizer(vn);
1411     _phase->set_ctrl(vn, _phase->get_ctrl(opd));
1412 #ifdef ASSERT
1413     if (TraceNewVectors) {
1414       tty->print("new Vector node: ");
1415       vn->dump();
1416     }
1417 #endif
1418     return vn;
1419   }
1420 
1421   // Insert pack operation
1422   BasicType bt = velt_basic_type(p0);
1423   PackNode* pk = PackNode::make(_phase->C, opd, vlen, bt);
1424   DEBUG_ONLY( const BasicType opd_bt = opd->bottom_type()->basic_type(); )
1425 
1426   for (uint i = 1; i < vlen; i++) {
1427     Node* pi = p->at(i);
1428     Node* in = pi->in(opd_idx);
1429     assert(my_pack(in) == NULL, "Should already have been unpacked");
1430     assert(opd_bt == in->bottom_type()->basic_type(), "all same type");
1431     pk->add_opd(i, in);
1432   }
1433   _phase->_igvn.register_new_node_with_optimizer(pk);
1434   _phase->set_ctrl(pk, _phase->get_ctrl(opd));
1435 #ifdef ASSERT
1436     if (TraceNewVectors) {
1437       tty->print("new Vector node: ");
1438       pk->dump();
1439     }
1440 #endif
1441   return pk;
1442 }
1443 
1444 //------------------------------insert_extracts---------------------------
1445 // If a use of pack p is not a vector use, then replace the
1446 // use with an extract operation.
1447 void SuperWord::insert_extracts(Node_List* p) {
1448   if (p->at(0)->is_Store()) return;
1449   assert(_n_idx_list.is_empty(), "empty (node,index) list");
1450 
1451   // Inspect each use of each pack member.  For each use that is
1452   // not a vector use, replace the use with an extract operation.
1453 
1454   for (uint i = 0; i < p->size(); i++) {
1455     Node* def = p->at(i);
1456     for (DUIterator_Fast jmax, j = def->fast_outs(jmax); j < jmax; j++) {
1457       Node* use = def->fast_out(j);
1458       for (uint k = 0; k < use->req(); k++) {
1459         Node* n = use->in(k);
1460         if (def == n) {
1461           if (!is_vector_use(use, k)) {
1462             _n_idx_list.push(use, k);
1463           }
1464         }
1465       }
1466     }
1467   }
1468 
1469   while (_n_idx_list.is_nonempty()) {
1470     Node* use = _n_idx_list.node();
1471     int   idx = _n_idx_list.index();
1472     _n_idx_list.pop();
1473     Node* def = use->in(idx);
1474 
1475     // Insert extract operation
1476     _igvn.hash_delete(def);
1477     int def_pos = alignment(def) / data_size(def);
1478 
1479     Node* ex = ExtractNode::make(_phase->C, def, def_pos, velt_basic_type(def));
1480     _phase->_igvn.register_new_node_with_optimizer(ex);
1481     _phase->set_ctrl(ex, _phase->get_ctrl(def));
1482     _igvn.replace_input_of(use, idx, ex);
1483     _igvn._worklist.push(def);
1484 
1485     bb_insert_after(ex, bb_idx(def));
1486     set_velt_type(ex, velt_type(def));
1487   }
1488 }
1489 
1490 //------------------------------is_vector_use---------------------------
1491 // Is use->in(u_idx) a vector use?
1492 bool SuperWord::is_vector_use(Node* use, int u_idx) {
1493   Node_List* u_pk = my_pack(use);
1494   if (u_pk == NULL) return false;
1495   Node* def = use->in(u_idx);
1496   Node_List* d_pk = my_pack(def);
1497   if (d_pk == NULL) {
1498     // check for scalar promotion
1499     Node* n = u_pk->at(0)->in(u_idx);
1500     for (uint i = 1; i < u_pk->size(); i++) {
1501       if (u_pk->at(i)->in(u_idx) != n) return false;
1502     }
1503     return true;
1504   }
1505   if (u_pk->size() != d_pk->size())
1506     return false;
1507   for (uint i = 0; i < u_pk->size(); i++) {
1508     Node* ui = u_pk->at(i);
1509     Node* di = d_pk->at(i);
1510     if (ui->in(u_idx) != di || alignment(ui) != alignment(di))
1511       return false;
1512   }
1513   return true;
1514 }
1515 
1516 //------------------------------construct_bb---------------------------
1517 // Construct reverse postorder list of block members
1518 void SuperWord::construct_bb() {
1519   Node* entry = bb();
1520 
1521   assert(_stk.length() == 0,            "stk is empty");
1522   assert(_block.length() == 0,          "block is empty");
1523   assert(_data_entry.length() == 0,     "data_entry is empty");
1524   assert(_mem_slice_head.length() == 0, "mem_slice_head is empty");
1525   assert(_mem_slice_tail.length() == 0, "mem_slice_tail is empty");
1526 
1527   // Find non-control nodes with no inputs from within block,
1528   // create a temporary map from node _idx to bb_idx for use
1529   // by the visited and post_visited sets,
1530   // and count number of nodes in block.
1531   int bb_ct = 0;
1532   for (uint i = 0; i < lpt()->_body.size(); i++ ) {
1533     Node *n = lpt()->_body.at(i);
1534     set_bb_idx(n, i); // Create a temporary map
1535     if (in_bb(n)) {
1536       bb_ct++;
1537       if (!n->is_CFG()) {
1538         bool found = false;
1539         for (uint j = 0; j < n->req(); j++) {
1540           Node* def = n->in(j);
1541           if (def && in_bb(def)) {
1542             found = true;
1543             break;
1544           }
1545         }
1546         if (!found) {
1547           assert(n != entry, "can't be entry");
1548           _data_entry.push(n);
1549         }
1550       }
1551     }
1552   }
1553 
1554   // Find memory slices (head and tail)
1555   for (DUIterator_Fast imax, i = lp()->fast_outs(imax); i < imax; i++) {
1556     Node *n = lp()->fast_out(i);
1557     if (in_bb(n) && (n->is_Phi() && n->bottom_type() == Type::MEMORY)) {
1558       Node* n_tail  = n->in(LoopNode::LoopBackControl);
1559       if (n_tail != n->in(LoopNode::EntryControl)) {
1560         _mem_slice_head.push(n);
1561         _mem_slice_tail.push(n_tail);
1562       }
1563     }
1564   }
1565 
1566   // Create an RPO list of nodes in block
1567 
1568   visited_clear();
1569   post_visited_clear();
1570 
1571   // Push all non-control nodes with no inputs from within block, then control entry
1572   for (int j = 0; j < _data_entry.length(); j++) {
1573     Node* n = _data_entry.at(j);
1574     visited_set(n);
1575     _stk.push(n);
1576   }
1577   visited_set(entry);
1578   _stk.push(entry);
1579 
1580   // Do a depth first walk over out edges
1581   int rpo_idx = bb_ct - 1;
1582   int size;
1583   while ((size = _stk.length()) > 0) {
1584     Node* n = _stk.top(); // Leave node on stack
1585     if (!visited_test_set(n)) {
1586       // forward arc in graph
1587     } else if (!post_visited_test(n)) {
1588       // cross or back arc
1589       for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
1590         Node *use = n->fast_out(i);
1591         if (in_bb(use) && !visited_test(use) &&
1592             // Don't go around backedge
1593             (!use->is_Phi() || n == entry)) {
1594           _stk.push(use);
1595         }
1596       }
1597       if (_stk.length() == size) {
1598         // There were no additional uses, post visit node now
1599         _stk.pop(); // Remove node from stack
1600         assert(rpo_idx >= 0, "");
1601         _block.at_put_grow(rpo_idx, n);
1602         rpo_idx--;
1603         post_visited_set(n);
1604         assert(rpo_idx >= 0 || _stk.is_empty(), "");
1605       }
1606     } else {
1607       _stk.pop(); // Remove post-visited node from stack
1608     }
1609   }
1610 
1611   // Create real map of block indices for nodes
1612   for (int j = 0; j < _block.length(); j++) {
1613     Node* n = _block.at(j);
1614     set_bb_idx(n, j);
1615   }
1616 
1617   initialize_bb(); // Ensure extra info is allocated.
1618 
1619 #ifndef PRODUCT
1620   if (TraceSuperWord) {
1621     print_bb();
1622     tty->print_cr("\ndata entry nodes: %s", _data_entry.length() > 0 ? "" : "NONE");
1623     for (int m = 0; m < _data_entry.length(); m++) {
1624       tty->print("%3d ", m);
1625       _data_entry.at(m)->dump();
1626     }
1627     tty->print_cr("\nmemory slices: %s", _mem_slice_head.length() > 0 ? "" : "NONE");
1628     for (int m = 0; m < _mem_slice_head.length(); m++) {
1629       tty->print("%3d ", m); _mem_slice_head.at(m)->dump();
1630       tty->print("    ");    _mem_slice_tail.at(m)->dump();
1631     }
1632   }
1633 #endif
1634   assert(rpo_idx == -1 && bb_ct == _block.length(), "all block members found");
1635 }
1636 
1637 //------------------------------initialize_bb---------------------------
1638 // Initialize per node info
1639 void SuperWord::initialize_bb() {
1640   Node* last = _block.at(_block.length() - 1);
1641   grow_node_info(bb_idx(last));
1642 }
1643 
1644 //------------------------------bb_insert_after---------------------------
1645 // Insert n into block after pos
1646 void SuperWord::bb_insert_after(Node* n, int pos) {
1647   int n_pos = pos + 1;
1648   // Make room
1649   for (int i = _block.length() - 1; i >= n_pos; i--) {
1650     _block.at_put_grow(i+1, _block.at(i));
1651   }
1652   for (int j = _node_info.length() - 1; j >= n_pos; j--) {
1653     _node_info.at_put_grow(j+1, _node_info.at(j));
1654   }
1655   // Set value
1656   _block.at_put_grow(n_pos, n);
1657   _node_info.at_put_grow(n_pos, SWNodeInfo::initial);
1658   // Adjust map from node->_idx to _block index
1659   for (int i = n_pos; i < _block.length(); i++) {
1660     set_bb_idx(_block.at(i), i);
1661   }
1662 }
1663 
1664 //------------------------------compute_max_depth---------------------------
1665 // Compute max depth for expressions from beginning of block
1666 // Use to prune search paths during test for independence.
1667 void SuperWord::compute_max_depth() {
1668   int ct = 0;
1669   bool again;
1670   do {
1671     again = false;
1672     for (int i = 0; i < _block.length(); i++) {
1673       Node* n = _block.at(i);
1674       if (!n->is_Phi()) {
1675         int d_orig = depth(n);
1676         int d_in   = 0;
1677         for (DepPreds preds(n, _dg); !preds.done(); preds.next()) {
1678           Node* pred = preds.current();
1679           if (in_bb(pred)) {
1680             d_in = MAX2(d_in, depth(pred));
1681           }
1682         }
1683         if (d_in + 1 != d_orig) {
1684           set_depth(n, d_in + 1);
1685           again = true;
1686         }
1687       }
1688     }
1689     ct++;
1690   } while (again);
1691 #ifndef PRODUCT
1692   if (TraceSuperWord && Verbose)
1693     tty->print_cr("compute_max_depth iterated: %d times", ct);
1694 #endif
1695 }
1696 
1697 //-------------------------compute_vector_element_type-----------------------
1698 // Compute necessary vector element type for expressions
1699 // This propagates backwards a narrower integer type when the
1700 // upper bits of the value are not needed.
1701 // Example:  char a,b,c;  a = b + c;
1702 // Normally the type of the add is integer, but for packed character
1703 // operations the type of the add needs to be char.
1704 void SuperWord::compute_vector_element_type() {
1705 #ifndef PRODUCT
1706   if (TraceSuperWord && Verbose)
1707     tty->print_cr("\ncompute_velt_type:");
1708 #endif
1709 
1710   // Initial type
1711   for (int i = 0; i < _block.length(); i++) {
1712     Node* n = _block.at(i);
1713     set_velt_type(n, container_type(n));
1714   }
1715 
1716   // Propagate narrowed type backwards through operations
1717   // that don't depend on higher order bits
1718   for (int i = _block.length() - 1; i >= 0; i--) {
1719     Node* n = _block.at(i);
1720     // Only integer types need be examined
1721     if (n->bottom_type()->isa_int()) {
1722       uint start, end;
1723       vector_opd_range(n, &start, &end);
1724       const Type* vt = velt_type(n);
1725 
1726       for (uint j = start; j < end; j++) {
1727         Node* in  = n->in(j);
1728         // Don't propagate through a type conversion
1729         if (n->bottom_type() != in->bottom_type())
1730           continue;
1731         switch(in->Opcode()) {
1732         case Op_AddI:    case Op_AddL:
1733         case Op_SubI:    case Op_SubL:
1734         case Op_MulI:    case Op_MulL:
1735         case Op_AndI:    case Op_AndL:
1736         case Op_OrI:     case Op_OrL:
1737         case Op_XorI:    case Op_XorL:
1738         case Op_LShiftI: case Op_LShiftL:
1739         case Op_CMoveI:  case Op_CMoveL:
1740           if (in_bb(in)) {
1741             bool same_type = true;
1742             for (DUIterator_Fast kmax, k = in->fast_outs(kmax); k < kmax; k++) {
1743               Node *use = in->fast_out(k);
1744               if (!in_bb(use) || !same_velt_type(use, n)) {
1745                 same_type = false;
1746                 break;
1747               }
1748             }
1749             if (same_type) {
1750               set_velt_type(in, vt);
1751             }
1752           }
1753         }
1754       }
1755     }
1756   }
1757 #ifndef PRODUCT
1758   if (TraceSuperWord && Verbose) {
1759     for (int i = 0; i < _block.length(); i++) {
1760       Node* n = _block.at(i);
1761       velt_type(n)->dump();
1762       tty->print("\t");
1763       n->dump();
1764     }
1765   }
1766 #endif
1767 }
1768 
1769 //------------------------------memory_alignment---------------------------
1770 // Alignment within a vector memory reference
1771 int SuperWord::memory_alignment(MemNode* s, int iv_adjust_in_bytes) {
1772   SWPointer p(s, this);
1773   if (!p.valid()) {
1774     return bottom_align;
1775   }
1776   int vw = vector_width_in_bytes(s);
1777   if (vw < 2) {
1778     return bottom_align; // No vectors for this type
1779   }
1780   int offset  = p.offset_in_bytes();
1781   offset     += iv_adjust_in_bytes;
1782   int off_rem = offset % vw;
1783   int off_mod = off_rem >= 0 ? off_rem : off_rem + vw;
1784   return off_mod;
1785 }
1786 
1787 //---------------------------container_type---------------------------
1788 // Smallest type containing range of values
1789 const Type* SuperWord::container_type(Node* n) {
1790   if (n->is_Mem()) {
1791     return Type::get_const_basic_type(n->as_Mem()->memory_type());
1792   }
1793   const Type* t = _igvn.type(n);
1794   if (t->basic_type() == T_INT) {
1795     if (t->higher_equal(TypeInt::BOOL))  return TypeInt::BOOL;
1796     if (t->higher_equal(TypeInt::BYTE))  return TypeInt::BYTE;
1797     if (t->higher_equal(TypeInt::CHAR))  return TypeInt::CHAR;
1798     if (t->higher_equal(TypeInt::SHORT)) return TypeInt::SHORT;
1799     return TypeInt::INT;
1800   }
1801   return t;
1802 }
1803 
1804 bool SuperWord::same_velt_type(Node* n1, Node* n2) {
1805   const Type* vt1 = velt_type(n1);
1806   const Type* vt2 = velt_type(n1);
1807   if (vt1->basic_type() == T_INT && vt2->basic_type() == T_INT) {
1808     // Compare vectors element sizes for integer types.
1809     return data_size(n1) == data_size(n2);
1810   }
1811   return vt1 == vt2;
1812 }
1813 
1814 //-------------------------vector_opd_range-----------------------
1815 // (Start, end] half-open range defining which operands are vector
1816 void SuperWord::vector_opd_range(Node* n, uint* start, uint* end) {
1817   switch (n->Opcode()) {
1818   case Op_LoadB:   case Op_LoadUB:
1819   case Op_LoadS:   case Op_LoadUS:
1820   case Op_LoadI:   case Op_LoadL:
1821   case Op_LoadF:   case Op_LoadD:
1822   case Op_LoadP:
1823     *start = 0;
1824     *end   = 0;
1825     return;
1826   case Op_StoreB:  case Op_StoreC:
1827   case Op_StoreI:  case Op_StoreL:
1828   case Op_StoreF:  case Op_StoreD:
1829   case Op_StoreP:
1830     *start = MemNode::ValueIn;
1831     *end   = *start + 1;
1832     return;
1833   case Op_LShiftI: case Op_LShiftL:
1834     *start = 1;
1835     *end   = 2;
1836     return;
1837   case Op_CMoveI:  case Op_CMoveL:  case Op_CMoveF:  case Op_CMoveD:
1838     *start = 2;
1839     *end   = n->req();
1840     return;
1841   }
1842   *start = 1;
1843   *end   = n->req(); // default is all operands
1844 }
1845 
1846 //------------------------------in_packset---------------------------
1847 // Are s1 and s2 in a pack pair and ordered as s1,s2?
1848 bool SuperWord::in_packset(Node* s1, Node* s2) {
1849   for (int i = 0; i < _packset.length(); i++) {
1850     Node_List* p = _packset.at(i);
1851     assert(p->size() == 2, "must be");
1852     if (p->at(0) == s1 && p->at(p->size()-1) == s2) {
1853       return true;
1854     }
1855   }
1856   return false;
1857 }
1858 
1859 //------------------------------in_pack---------------------------
1860 // Is s in pack p?
1861 Node_List* SuperWord::in_pack(Node* s, Node_List* p) {
1862   for (uint i = 0; i < p->size(); i++) {
1863     if (p->at(i) == s) {
1864       return p;
1865     }
1866   }
1867   return NULL;
1868 }
1869 
1870 //------------------------------remove_pack_at---------------------------
1871 // Remove the pack at position pos in the packset
1872 void SuperWord::remove_pack_at(int pos) {
1873   Node_List* p = _packset.at(pos);
1874   for (uint i = 0; i < p->size(); i++) {
1875     Node* s = p->at(i);
1876     set_my_pack(s, NULL);
1877   }
1878   _packset.remove_at(pos);
1879 }
1880 
1881 //------------------------------executed_first---------------------------
1882 // Return the node executed first in pack p.  Uses the RPO block list
1883 // to determine order.
1884 Node* SuperWord::executed_first(Node_List* p) {
1885   Node* n = p->at(0);
1886   int n_rpo = bb_idx(n);
1887   for (uint i = 1; i < p->size(); i++) {
1888     Node* s = p->at(i);
1889     int s_rpo = bb_idx(s);
1890     if (s_rpo < n_rpo) {
1891       n = s;
1892       n_rpo = s_rpo;
1893     }
1894   }
1895   return n;
1896 }
1897 
1898 //------------------------------executed_last---------------------------
1899 // Return the node executed last in pack p.
1900 Node* SuperWord::executed_last(Node_List* p) {
1901   Node* n = p->at(0);
1902   int n_rpo = bb_idx(n);
1903   for (uint i = 1; i < p->size(); i++) {
1904     Node* s = p->at(i);
1905     int s_rpo = bb_idx(s);
1906     if (s_rpo > n_rpo) {
1907       n = s;
1908       n_rpo = s_rpo;
1909     }
1910   }
1911   return n;
1912 }
1913 
1914 //----------------------------align_initial_loop_index---------------------------
1915 // Adjust pre-loop limit so that in main loop, a load/store reference
1916 // to align_to_ref will be a position zero in the vector.
1917 //   (iv + k) mod vector_align == 0
1918 void SuperWord::align_initial_loop_index(MemNode* align_to_ref) {
1919   CountedLoopNode *main_head = lp()->as_CountedLoop();
1920   assert(main_head->is_main_loop(), "");
1921   CountedLoopEndNode* pre_end = get_pre_loop_end(main_head);
1922   assert(pre_end != NULL, "");
1923   Node *pre_opaq1 = pre_end->limit();
1924   assert(pre_opaq1->Opcode() == Op_Opaque1, "");
1925   Opaque1Node *pre_opaq = (Opaque1Node*)pre_opaq1;
1926   Node *lim0 = pre_opaq->in(1);
1927 
1928   // Where we put new limit calculations
1929   Node *pre_ctrl = pre_end->loopnode()->in(LoopNode::EntryControl);
1930 
1931   // Ensure the original loop limit is available from the
1932   // pre-loop Opaque1 node.
1933   Node *orig_limit = pre_opaq->original_loop_limit();
1934   assert(orig_limit != NULL && _igvn.type(orig_limit) != Type::TOP, "");
1935 
1936   SWPointer align_to_ref_p(align_to_ref, this);
1937   assert(align_to_ref_p.valid(), "sanity");
1938 
1939   // Given:
1940   //     lim0 == original pre loop limit
1941   //     V == v_align (power of 2)
1942   //     invar == extra invariant piece of the address expression
1943   //     e == k [ +/- invar ]
1944   //
1945   // When reassociating expressions involving '%' the basic rules are:
1946   //     (a - b) % k == 0   =>  a % k == b % k
1947   // and:
1948   //     (a + b) % k == 0   =>  a % k == (k - b) % k
1949   //
1950   // For stride > 0 && scale > 0,
1951   //   Derive the new pre-loop limit "lim" such that the two constraints:
1952   //     (1) lim = lim0 + N           (where N is some positive integer < V)
1953   //     (2) (e + lim) % V == 0
1954   //   are true.
1955   //
1956   //   Substituting (1) into (2),
1957   //     (e + lim0 + N) % V == 0
1958   //   solve for N:
1959   //     N = (V - (e + lim0)) % V
1960   //   substitute back into (1), so that new limit
1961   //     lim = lim0 + (V - (e + lim0)) % V
1962   //
1963   // For stride > 0 && scale < 0
1964   //   Constraints:
1965   //     lim = lim0 + N
1966   //     (e - lim) % V == 0
1967   //   Solving for lim:
1968   //     (e - lim0 - N) % V == 0
1969   //     N = (e - lim0) % V
1970   //     lim = lim0 + (e - lim0) % V
1971   //
1972   // For stride < 0 && scale > 0
1973   //   Constraints:
1974   //     lim = lim0 - N
1975   //     (e + lim) % V == 0
1976   //   Solving for lim:
1977   //     (e + lim0 - N) % V == 0
1978   //     N = (e + lim0) % V
1979   //     lim = lim0 - (e + lim0) % V
1980   //
1981   // For stride < 0 && scale < 0
1982   //   Constraints:
1983   //     lim = lim0 - N
1984   //     (e - lim) % V == 0
1985   //   Solving for lim:
1986   //     (e - lim0 + N) % V == 0
1987   //     N = (V - (e - lim0)) % V
1988   //     lim = lim0 - (V - (e - lim0)) % V
1989 
1990   int vw = vector_width_in_bytes(align_to_ref);
1991   int stride   = iv_stride();
1992   int scale    = align_to_ref_p.scale_in_bytes();
1993   int elt_size = align_to_ref_p.memory_size();
1994   int v_align  = vw / elt_size;
1995   assert(v_align > 1, "sanity");
1996   int k        = align_to_ref_p.offset_in_bytes() / elt_size;
1997 
1998   Node *kn   = _igvn.intcon(k);
1999 
2000   Node *e = kn;
2001   if (align_to_ref_p.invar() != NULL) {
2002     // incorporate any extra invariant piece producing k +/- invar >>> log2(elt)
2003     Node* log2_elt = _igvn.intcon(exact_log2(elt_size));
2004     Node* aref     = new (_phase->C, 3) URShiftINode(align_to_ref_p.invar(), log2_elt);
2005     _phase->_igvn.register_new_node_with_optimizer(aref);
2006     _phase->set_ctrl(aref, pre_ctrl);
2007     if (align_to_ref_p.negate_invar()) {
2008       e = new (_phase->C, 3) SubINode(e, aref);
2009     } else {
2010       e = new (_phase->C, 3) AddINode(e, aref);
2011     }
2012     _phase->_igvn.register_new_node_with_optimizer(e);
2013     _phase->set_ctrl(e, pre_ctrl);
2014   }
2015   if (vw > ObjectAlignmentInBytes) {
2016     // incorporate base e +/- base && Mask >>> log2(elt)
2017     Node* mask = _igvn.MakeConX(~(-1 << exact_log2(vw)));
2018     Node* xbase = new(_phase->C, 2) CastP2XNode(NULL, align_to_ref_p.base());
2019     _phase->_igvn.register_new_node_with_optimizer(xbase);
2020     Node* masked_xbase  = new (_phase->C, 3) AndXNode(xbase, mask);
2021     _phase->_igvn.register_new_node_with_optimizer(masked_xbase);
2022 #ifdef _LP64
2023     masked_xbase  = new (_phase->C, 2) ConvL2INode(masked_xbase);
2024     _phase->_igvn.register_new_node_with_optimizer(masked_xbase);
2025 #endif
2026     Node* log2_elt = _igvn.intcon(exact_log2(elt_size));
2027     Node* bref     = new (_phase->C, 3) URShiftINode(masked_xbase, log2_elt);
2028     _phase->_igvn.register_new_node_with_optimizer(bref);
2029     _phase->set_ctrl(bref, pre_ctrl);
2030     e = new (_phase->C, 3) AddINode(e, bref);
2031     _phase->_igvn.register_new_node_with_optimizer(e);
2032     _phase->set_ctrl(e, pre_ctrl);
2033   }
2034 
2035   // compute e +/- lim0
2036   if (scale < 0) {
2037     e = new (_phase->C, 3) SubINode(e, lim0);
2038   } else {
2039     e = new (_phase->C, 3) AddINode(e, lim0);
2040   }
2041   _phase->_igvn.register_new_node_with_optimizer(e);
2042   _phase->set_ctrl(e, pre_ctrl);
2043 
2044   if (stride * scale > 0) {
2045     // compute V - (e +/- lim0)
2046     Node* va  = _igvn.intcon(v_align);
2047     e = new (_phase->C, 3) SubINode(va, e);
2048     _phase->_igvn.register_new_node_with_optimizer(e);
2049     _phase->set_ctrl(e, pre_ctrl);
2050   }
2051   // compute N = (exp) % V
2052   Node* va_msk = _igvn.intcon(v_align - 1);
2053   Node* N = new (_phase->C, 3) AndINode(e, va_msk);
2054   _phase->_igvn.register_new_node_with_optimizer(N);
2055   _phase->set_ctrl(N, pre_ctrl);
2056 
2057   //   substitute back into (1), so that new limit
2058   //     lim = lim0 + N
2059   Node* lim;
2060   if (stride < 0) {
2061     lim = new (_phase->C, 3) SubINode(lim0, N);
2062   } else {
2063     lim = new (_phase->C, 3) AddINode(lim0, N);
2064   }
2065   _phase->_igvn.register_new_node_with_optimizer(lim);
2066   _phase->set_ctrl(lim, pre_ctrl);
2067   Node* constrained =
2068     (stride > 0) ? (Node*) new (_phase->C,3) MinINode(lim, orig_limit)
2069                  : (Node*) new (_phase->C,3) MaxINode(lim, orig_limit);
2070   _phase->_igvn.register_new_node_with_optimizer(constrained);
2071   _phase->set_ctrl(constrained, pre_ctrl);
2072   _igvn.hash_delete(pre_opaq);
2073   pre_opaq->set_req(1, constrained);
2074 }
2075 
2076 //----------------------------get_pre_loop_end---------------------------
2077 // Find pre loop end from main loop.  Returns null if none.
2078 CountedLoopEndNode* SuperWord::get_pre_loop_end(CountedLoopNode *cl) {
2079   Node *ctrl = cl->in(LoopNode::EntryControl);
2080   if (!ctrl->is_IfTrue() && !ctrl->is_IfFalse()) return NULL;
2081   Node *iffm = ctrl->in(0);
2082   if (!iffm->is_If()) return NULL;
2083   Node *p_f = iffm->in(0);
2084   if (!p_f->is_IfFalse()) return NULL;
2085   if (!p_f->in(0)->is_CountedLoopEnd()) return NULL;
2086   CountedLoopEndNode *pre_end = p_f->in(0)->as_CountedLoopEnd();
2087   if (!pre_end->loopnode()->is_pre_loop()) return NULL;
2088   return pre_end;
2089 }
2090 
2091 
2092 //------------------------------init---------------------------
2093 void SuperWord::init() {
2094   _dg.init();
2095   _packset.clear();
2096   _disjoint_ptrs.clear();
2097   _block.clear();
2098   _data_entry.clear();
2099   _mem_slice_head.clear();
2100   _mem_slice_tail.clear();
2101   _node_info.clear();
2102   _align_to_ref = NULL;
2103   _lpt = NULL;
2104   _lp = NULL;
2105   _bb = NULL;
2106   _iv = NULL;
2107 }
2108 
2109 //------------------------------print_packset---------------------------
2110 void SuperWord::print_packset() {
2111 #ifndef PRODUCT
2112   tty->print_cr("packset");
2113   for (int i = 0; i < _packset.length(); i++) {
2114     tty->print_cr("Pack: %d", i);
2115     Node_List* p = _packset.at(i);
2116     print_pack(p);
2117   }
2118 #endif
2119 }
2120 
2121 //------------------------------print_pack---------------------------
2122 void SuperWord::print_pack(Node_List* p) {
2123   for (uint i = 0; i < p->size(); i++) {
2124     print_stmt(p->at(i));
2125   }
2126 }
2127 
2128 //------------------------------print_bb---------------------------
2129 void SuperWord::print_bb() {
2130 #ifndef PRODUCT
2131   tty->print_cr("\nBlock");
2132   for (int i = 0; i < _block.length(); i++) {
2133     Node* n = _block.at(i);
2134     tty->print("%d ", i);
2135     if (n) {
2136       n->dump();
2137     }
2138   }
2139 #endif
2140 }
2141 
2142 //------------------------------print_stmt---------------------------
2143 void SuperWord::print_stmt(Node* s) {
2144 #ifndef PRODUCT
2145   tty->print(" align: %d \t", alignment(s));
2146   s->dump();
2147 #endif
2148 }
2149 
2150 //------------------------------blank---------------------------
2151 char* SuperWord::blank(uint depth) {
2152   static char blanks[101];
2153   assert(depth < 101, "too deep");
2154   for (uint i = 0; i < depth; i++) blanks[i] = ' ';
2155   blanks[depth] = '\0';
2156   return blanks;
2157 }
2158 
2159 
2160 //==============================SWPointer===========================
2161 
2162 //----------------------------SWPointer------------------------
2163 SWPointer::SWPointer(MemNode* mem, SuperWord* slp) :
2164   _mem(mem), _slp(slp),  _base(NULL),  _adr(NULL),
2165   _scale(0), _offset(0), _invar(NULL), _negate_invar(false) {
2166 
2167   Node* adr = mem->in(MemNode::Address);
2168   if (!adr->is_AddP()) {
2169     assert(!valid(), "too complex");
2170     return;
2171   }
2172   // Match AddP(base, AddP(ptr, k*iv [+ invariant]), constant)
2173   Node* base = adr->in(AddPNode::Base);
2174   //unsafe reference could not be aligned appropriately without runtime checking
2175   if (base == NULL || base->bottom_type() == Type::TOP) {
2176     assert(!valid(), "unsafe access");
2177     return;
2178   }
2179   for (int i = 0; i < 3; i++) {
2180     if (!scaled_iv_plus_offset(adr->in(AddPNode::Offset))) {
2181       assert(!valid(), "too complex");
2182       return;
2183     }
2184     adr = adr->in(AddPNode::Address);
2185     if (base == adr || !adr->is_AddP()) {
2186       break; // stop looking at addp's
2187     }
2188   }
2189   _base = base;
2190   _adr  = adr;
2191   assert(valid(), "Usable");
2192 }
2193 
2194 // Following is used to create a temporary object during
2195 // the pattern match of an address expression.
2196 SWPointer::SWPointer(SWPointer* p) :
2197   _mem(p->_mem), _slp(p->_slp),  _base(NULL),  _adr(NULL),
2198   _scale(0), _offset(0), _invar(NULL), _negate_invar(false) {}
2199 
2200 //------------------------scaled_iv_plus_offset--------------------
2201 // Match: k*iv + offset
2202 // where: k is a constant that maybe zero, and
2203 //        offset is (k2 [+/- invariant]) where k2 maybe zero and invariant is optional
2204 bool SWPointer::scaled_iv_plus_offset(Node* n) {
2205   if (scaled_iv(n)) {
2206     return true;
2207   }
2208   if (offset_plus_k(n)) {
2209     return true;
2210   }
2211   int opc = n->Opcode();
2212   if (opc == Op_AddI) {
2213     if (scaled_iv(n->in(1)) && offset_plus_k(n->in(2))) {
2214       return true;
2215     }
2216     if (scaled_iv(n->in(2)) && offset_plus_k(n->in(1))) {
2217       return true;
2218     }
2219   } else if (opc == Op_SubI) {
2220     if (scaled_iv(n->in(1)) && offset_plus_k(n->in(2), true)) {
2221       return true;
2222     }
2223     if (scaled_iv(n->in(2)) && offset_plus_k(n->in(1))) {
2224       _scale *= -1;
2225       return true;
2226     }
2227   }
2228   return false;
2229 }
2230 
2231 //----------------------------scaled_iv------------------------
2232 // Match: k*iv where k is a constant that's not zero
2233 bool SWPointer::scaled_iv(Node* n) {
2234   if (_scale != 0) {
2235     return false;  // already found a scale
2236   }
2237   if (n == iv()) {
2238     _scale = 1;
2239     return true;
2240   }
2241   int opc = n->Opcode();
2242   if (opc == Op_MulI) {
2243     if (n->in(1) == iv() && n->in(2)->is_Con()) {
2244       _scale = n->in(2)->get_int();
2245       return true;
2246     } else if (n->in(2) == iv() && n->in(1)->is_Con()) {
2247       _scale = n->in(1)->get_int();
2248       return true;
2249     }
2250   } else if (opc == Op_LShiftI) {
2251     if (n->in(1) == iv() && n->in(2)->is_Con()) {
2252       _scale = 1 << n->in(2)->get_int();
2253       return true;
2254     }
2255   } else if (opc == Op_ConvI2L) {
2256     if (scaled_iv_plus_offset(n->in(1))) {
2257       return true;
2258     }
2259   } else if (opc == Op_LShiftL) {
2260     if (!has_iv() && _invar == NULL) {
2261       // Need to preserve the current _offset value, so
2262       // create a temporary object for this expression subtree.
2263       // Hacky, so should re-engineer the address pattern match.
2264       SWPointer tmp(this);
2265       if (tmp.scaled_iv_plus_offset(n->in(1))) {
2266         if (tmp._invar == NULL) {
2267           int mult = 1 << n->in(2)->get_int();
2268           _scale   = tmp._scale  * mult;
2269           _offset += tmp._offset * mult;
2270           return true;
2271         }
2272       }
2273     }
2274   }
2275   return false;
2276 }
2277 
2278 //----------------------------offset_plus_k------------------------
2279 // Match: offset is (k [+/- invariant])
2280 // where k maybe zero and invariant is optional, but not both.
2281 bool SWPointer::offset_plus_k(Node* n, bool negate) {
2282   int opc = n->Opcode();
2283   if (opc == Op_ConI) {
2284     _offset += negate ? -(n->get_int()) : n->get_int();
2285     return true;
2286   } else if (opc == Op_ConL) {
2287     // Okay if value fits into an int
2288     const TypeLong* t = n->find_long_type();
2289     if (t->higher_equal(TypeLong::INT)) {
2290       jlong loff = n->get_long();
2291       jint  off  = (jint)loff;
2292       _offset += negate ? -off : loff;
2293       return true;
2294     }
2295     return false;
2296   }
2297   if (_invar != NULL) return false; // already have an invariant
2298   if (opc == Op_AddI) {
2299     if (n->in(2)->is_Con() && invariant(n->in(1))) {
2300       _negate_invar = negate;
2301       _invar = n->in(1);
2302       _offset += negate ? -(n->in(2)->get_int()) : n->in(2)->get_int();
2303       return true;
2304     } else if (n->in(1)->is_Con() && invariant(n->in(2))) {
2305       _offset += negate ? -(n->in(1)->get_int()) : n->in(1)->get_int();
2306       _negate_invar = negate;
2307       _invar = n->in(2);
2308       return true;
2309     }
2310   }
2311   if (opc == Op_SubI) {
2312     if (n->in(2)->is_Con() && invariant(n->in(1))) {
2313       _negate_invar = negate;
2314       _invar = n->in(1);
2315       _offset += !negate ? -(n->in(2)->get_int()) : n->in(2)->get_int();
2316       return true;
2317     } else if (n->in(1)->is_Con() && invariant(n->in(2))) {
2318       _offset += negate ? -(n->in(1)->get_int()) : n->in(1)->get_int();
2319       _negate_invar = !negate;
2320       _invar = n->in(2);
2321       return true;
2322     }
2323   }
2324   if (invariant(n)) {
2325     _negate_invar = negate;
2326     _invar = n;
2327     return true;
2328   }
2329   return false;
2330 }
2331 
2332 //----------------------------print------------------------
2333 void SWPointer::print() {
2334 #ifndef PRODUCT
2335   tty->print("base: %d  adr: %d  scale: %d  offset: %d  invar: %c%d\n",
2336              _base != NULL ? _base->_idx : 0,
2337              _adr  != NULL ? _adr->_idx  : 0,
2338              _scale, _offset,
2339              _negate_invar?'-':'+',
2340              _invar != NULL ? _invar->_idx : 0);
2341 #endif
2342 }
2343 
2344 // ========================= OrderedPair =====================
2345 
2346 const OrderedPair OrderedPair::initial;
2347 
2348 // ========================= SWNodeInfo =====================
2349 
2350 const SWNodeInfo SWNodeInfo::initial;
2351 
2352 
2353 // ============================ DepGraph ===========================
2354 
2355 //------------------------------make_node---------------------------
2356 // Make a new dependence graph node for an ideal node.
2357 DepMem* DepGraph::make_node(Node* node) {
2358   DepMem* m = new (_arena) DepMem(node);
2359   if (node != NULL) {
2360     assert(_map.at_grow(node->_idx) == NULL, "one init only");
2361     _map.at_put_grow(node->_idx, m);
2362   }
2363   return m;
2364 }
2365 
2366 //------------------------------make_edge---------------------------
2367 // Make a new dependence graph edge from dpred -> dsucc
2368 DepEdge* DepGraph::make_edge(DepMem* dpred, DepMem* dsucc) {
2369   DepEdge* e = new (_arena) DepEdge(dpred, dsucc, dsucc->in_head(), dpred->out_head());
2370   dpred->set_out_head(e);
2371   dsucc->set_in_head(e);
2372   return e;
2373 }
2374 
2375 // ========================== DepMem ========================
2376 
2377 //------------------------------in_cnt---------------------------
2378 int DepMem::in_cnt() {
2379   int ct = 0;
2380   for (DepEdge* e = _in_head; e != NULL; e = e->next_in()) ct++;
2381   return ct;
2382 }
2383 
2384 //------------------------------out_cnt---------------------------
2385 int DepMem::out_cnt() {
2386   int ct = 0;
2387   for (DepEdge* e = _out_head; e != NULL; e = e->next_out()) ct++;
2388   return ct;
2389 }
2390 
2391 //------------------------------print-----------------------------
2392 void DepMem::print() {
2393 #ifndef PRODUCT
2394   tty->print("  DepNode %d (", _node->_idx);
2395   for (DepEdge* p = _in_head; p != NULL; p = p->next_in()) {
2396     Node* pred = p->pred()->node();
2397     tty->print(" %d", pred != NULL ? pred->_idx : 0);
2398   }
2399   tty->print(") [");
2400   for (DepEdge* s = _out_head; s != NULL; s = s->next_out()) {
2401     Node* succ = s->succ()->node();
2402     tty->print(" %d", succ != NULL ? succ->_idx : 0);
2403   }
2404   tty->print_cr(" ]");
2405 #endif
2406 }
2407 
2408 // =========================== DepEdge =========================
2409 
2410 //------------------------------DepPreds---------------------------
2411 void DepEdge::print() {
2412 #ifndef PRODUCT
2413   tty->print_cr("DepEdge: %d [ %d ]", _pred->node()->_idx, _succ->node()->_idx);
2414 #endif
2415 }
2416 
2417 // =========================== DepPreds =========================
2418 // Iterator over predecessor edges in the dependence graph.
2419 
2420 //------------------------------DepPreds---------------------------
2421 DepPreds::DepPreds(Node* n, DepGraph& dg) {
2422   _n = n;
2423   _done = false;
2424   if (_n->is_Store() || _n->is_Load()) {
2425     _next_idx = MemNode::Address;
2426     _end_idx  = n->req();
2427     _dep_next = dg.dep(_n)->in_head();
2428   } else if (_n->is_Mem()) {
2429     _next_idx = 0;
2430     _end_idx  = 0;
2431     _dep_next = dg.dep(_n)->in_head();
2432   } else {
2433     _next_idx = 1;
2434     _end_idx  = _n->req();
2435     _dep_next = NULL;
2436   }
2437   next();
2438 }
2439 
2440 //------------------------------next---------------------------
2441 void DepPreds::next() {
2442   if (_dep_next != NULL) {
2443     _current  = _dep_next->pred()->node();
2444     _dep_next = _dep_next->next_in();
2445   } else if (_next_idx < _end_idx) {
2446     _current  = _n->in(_next_idx++);
2447   } else {
2448     _done = true;
2449   }
2450 }
2451 
2452 // =========================== DepSuccs =========================
2453 // Iterator over successor edges in the dependence graph.
2454 
2455 //------------------------------DepSuccs---------------------------
2456 DepSuccs::DepSuccs(Node* n, DepGraph& dg) {
2457   _n = n;
2458   _done = false;
2459   if (_n->is_Load()) {
2460     _next_idx = 0;
2461     _end_idx  = _n->outcnt();
2462     _dep_next = dg.dep(_n)->out_head();
2463   } else if (_n->is_Mem() || _n->is_Phi() && _n->bottom_type() == Type::MEMORY) {
2464     _next_idx = 0;
2465     _end_idx  = 0;
2466     _dep_next = dg.dep(_n)->out_head();
2467   } else {
2468     _next_idx = 0;
2469     _end_idx  = _n->outcnt();
2470     _dep_next = NULL;
2471   }
2472   next();
2473 }
2474 
2475 //-------------------------------next---------------------------
2476 void DepSuccs::next() {
2477   if (_dep_next != NULL) {
2478     _current  = _dep_next->succ()->node();
2479     _dep_next = _dep_next->next_out();
2480   } else if (_next_idx < _end_idx) {
2481     _current  = _n->raw_out(_next_idx++);
2482   } else {
2483     _done = true;
2484   }
2485 }