1 /*
   2  * Copyright (c) 1997, 2015, 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 
  25 #ifndef SHARE_VM_OPTO_MEMNODE_HPP
  26 #define SHARE_VM_OPTO_MEMNODE_HPP
  27 
  28 #include "opto/multnode.hpp"
  29 #include "opto/node.hpp"
  30 #include "opto/opcodes.hpp"
  31 #include "opto/type.hpp"
  32 
  33 // Portions of code courtesy of Clifford Click
  34 
  35 class MultiNode;
  36 class PhaseCCP;
  37 class PhaseTransform;
  38 
  39 //------------------------------MemNode----------------------------------------
  40 // Load or Store, possibly throwing a NULL pointer exception
  41 class MemNode : public Node {
  42 private:
  43   bool _unaligned_access; // Unaligned access from unsafe
  44   bool _mismatched_access; // Mismatched access from unsafe: byte read in integer array for instance
  45 protected:
  46 #ifdef ASSERT
  47   const TypePtr* _adr_type;     // What kind of memory is being addressed?
  48 #endif
  49   virtual uint size_of() const;
  50 public:
  51   enum { Control,               // When is it safe to do this load?
  52          Memory,                // Chunk of memory is being loaded from
  53          Address,               // Actually address, derived from base
  54          ValueIn,               // Value to store
  55          OopStore               // Preceeding oop store, only in StoreCM
  56   };
  57   typedef enum { unordered = 0,
  58                  acquire,       // Load has to acquire or be succeeded by MemBarAcquire.
  59                  release,       // Store has to release or be preceded by MemBarRelease.
  60                  seqcst,        // LoadStore has to have both acquire and release semantics.
  61                  unset          // The memory ordering is not set (used for testing)
  62   } MemOrd;
  63 protected:
  64   MemNode( Node *c0, Node *c1, Node *c2, const TypePtr* at )
  65     : Node(c0,c1,c2   ), _unaligned_access(false), _mismatched_access(false) {
  66     init_class_id(Class_Mem);
  67     debug_only(_adr_type=at; adr_type();)
  68   }
  69   MemNode( Node *c0, Node *c1, Node *c2, const TypePtr* at, Node *c3 )
  70     : Node(c0,c1,c2,c3), _unaligned_access(false), _mismatched_access(false) {
  71     init_class_id(Class_Mem);
  72     debug_only(_adr_type=at; adr_type();)
  73   }
  74   MemNode( Node *c0, Node *c1, Node *c2, const TypePtr* at, Node *c3, Node *c4)
  75     : Node(c0,c1,c2,c3,c4), _unaligned_access(false), _mismatched_access(false) {
  76     init_class_id(Class_Mem);
  77     debug_only(_adr_type=at; adr_type();)
  78   }
  79 
  80   virtual Node* find_previous_arraycopy(PhaseTransform* phase, Node* ld_alloc, Node*& mem, bool can_see_stored_value) const { return NULL; }
  81   static bool check_if_adr_maybe_raw(Node* adr);
  82 
  83 public:
  84   // Helpers for the optimizer.  Documented in memnode.cpp.
  85   static bool detect_ptr_independence(Node* p1, AllocateNode* a1,
  86                                       Node* p2, AllocateNode* a2,
  87                                       PhaseTransform* phase);
  88   static bool adr_phi_is_loop_invariant(Node* adr_phi, Node* cast);
  89 
  90   static Node *optimize_simple_memory_chain(Node *mchain, const TypeOopPtr *t_oop, Node *load, PhaseGVN *phase);
  91   static Node *optimize_memory_chain(Node *mchain, const TypePtr *t_adr, Node *load, PhaseGVN *phase);
  92   // This one should probably be a phase-specific function:
  93   static bool all_controls_dominate(Node* dom, Node* sub);
  94 
  95   virtual const class TypePtr *adr_type() const;  // returns bottom_type of address
  96 
  97   // Shared code for Ideal methods:
  98   Node *Ideal_common(PhaseGVN *phase, bool can_reshape);  // Return -1 for short-circuit NULL.
  99 
 100   // Helper function for adr_type() implementations.
 101   static const TypePtr* calculate_adr_type(const Type* t, const TypePtr* cross_check = NULL);
 102 
 103   // Raw access function, to allow copying of adr_type efficiently in
 104   // product builds and retain the debug info for debug builds.
 105   const TypePtr *raw_adr_type() const {
 106 #ifdef ASSERT
 107     return _adr_type;
 108 #else
 109     return 0;
 110 #endif
 111   }
 112 
 113   // Map a load or store opcode to its corresponding store opcode.
 114   // (Return -1 if unknown.)
 115   virtual int store_Opcode() const { return -1; }
 116 
 117   // What is the type of the value in memory?  (T_VOID mean "unspecified".)
 118   virtual BasicType memory_type() const = 0;
 119   virtual int memory_size() const {
 120 #ifdef ASSERT
 121     return type2aelembytes(memory_type(), true);
 122 #else
 123     return type2aelembytes(memory_type());
 124 #endif
 125   }
 126 
 127   // Search through memory states which precede this node (load or store).
 128   // Look for an exact match for the address, with no intervening
 129   // aliased stores.
 130   Node* find_previous_store(PhaseTransform* phase);
 131 
 132   // Can this node (load or store) accurately see a stored value in
 133   // the given memory state?  (The state may or may not be in(Memory).)
 134   Node* can_see_stored_value(Node* st, PhaseTransform* phase) const;
 135 
 136   void set_unaligned_access() { _unaligned_access = true; }
 137   bool is_unaligned_access() const { return _unaligned_access; }
 138   void set_mismatched_access() { _mismatched_access = true; }
 139   bool is_mismatched_access() const { return _mismatched_access; }
 140 
 141 #ifndef PRODUCT
 142   static void dump_adr_type(const Node* mem, const TypePtr* adr_type, outputStream *st);
 143   virtual void dump_spec(outputStream *st) const;
 144 #endif
 145 };
 146 
 147 //------------------------------LoadNode---------------------------------------
 148 // Load value; requires Memory and Address
 149 class LoadNode : public MemNode {
 150 public:
 151   // Some loads (from unsafe) should be pinned: they don't depend only
 152   // on the dominating test.  The field _control_dependency below records
 153   // whether that node depends only on the dominating test.
 154   // Methods used to build LoadNodes pass an argument of type enum
 155   // ControlDependency instead of a boolean because those methods
 156   // typically have multiple boolean parameters with default values:
 157   // passing the wrong boolean to one of these parameters by mistake
 158   // goes easily unnoticed. Using an enum, the compiler can check that
 159   // the type of a value and the type of the parameter match.
 160   enum ControlDependency {
 161     Pinned,
 162     DependsOnlyOnTest
 163   };
 164 private:
 165   // LoadNode::hash() doesn't take the _control_dependency field
 166   // into account: If the graph already has a non-pinned LoadNode and
 167   // we add a pinned LoadNode with the same inputs, it's safe for GVN
 168   // to replace the pinned LoadNode with the non-pinned LoadNode,
 169   // otherwise it wouldn't be safe to have a non pinned LoadNode with
 170   // those inputs in the first place. If the graph already has a
 171   // pinned LoadNode and we add a non pinned LoadNode with the same
 172   // inputs, it's safe (but suboptimal) for GVN to replace the
 173   // non-pinned LoadNode by the pinned LoadNode.
 174   ControlDependency _control_dependency;
 175 
 176   // On platforms with weak memory ordering (e.g., PPC, Ia64) we distinguish
 177   // loads that can be reordered, and such requiring acquire semantics to
 178   // adhere to the Java specification.  The required behaviour is stored in
 179   // this field.
 180   const MemOrd _mo;
 181 
 182 protected:
 183   virtual uint cmp(const Node &n) const;
 184   virtual uint size_of() const; // Size is bigger
 185   // Should LoadNode::Ideal() attempt to remove control edges?
 186   virtual bool can_remove_control() const;
 187   const Type* const _type;      // What kind of value is loaded?
 188 
 189   virtual Node* find_previous_arraycopy(PhaseTransform* phase, Node* ld_alloc, Node*& mem, bool can_see_stored_value) const;
 190 public:
 191 
 192   LoadNode(Node *c, Node *mem, Node *adr, const TypePtr* at, const Type *rt, MemOrd mo, ControlDependency control_dependency)
 193     : MemNode(c,mem,adr,at), _control_dependency(control_dependency), _mo(mo), _type(rt) {
 194     init_class_id(Class_Load);
 195   }
 196   inline bool is_unordered() const { return !is_acquire(); }
 197   inline bool is_acquire() const {
 198     assert(_mo == unordered || _mo == acquire, "unexpected");
 199     return _mo == acquire;
 200   }
 201   inline bool is_unsigned() const {
 202     int lop = Opcode();
 203     return (lop == Op_LoadUB) || (lop == Op_LoadUS);
 204   }
 205 
 206   // Polymorphic factory method:
 207   static Node* make(PhaseGVN& gvn, Node *c, Node *mem, Node *adr,
 208                     const TypePtr* at, const Type *rt, BasicType bt,
 209                     MemOrd mo, ControlDependency control_dependency = DependsOnlyOnTest,
 210                     bool unaligned = false, bool mismatched = false);
 211 
 212   virtual uint hash()   const;  // Check the type
 213 
 214   // Handle algebraic identities here.  If we have an identity, return the Node
 215   // we are equivalent to.  We look for Load of a Store.
 216   virtual Node* Identity(PhaseGVN* phase);
 217 
 218   // If the load is from Field memory and the pointer is non-null, it might be possible to
 219   // zero out the control input.
 220   // If the offset is constant and the base is an object allocation,
 221   // try to hook me up to the exact initializing store.
 222   virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
 223 
 224   // Split instance field load through Phi.
 225   Node* split_through_phi(PhaseGVN *phase);
 226 
 227   // Recover original value from boxed values
 228   Node *eliminate_autobox(PhaseGVN *phase);
 229 
 230   // Compute a new Type for this node.  Basically we just do the pre-check,
 231   // then call the virtual add() to set the type.
 232   virtual const Type* Value(PhaseGVN* phase) const;
 233 
 234   // Common methods for LoadKlass and LoadNKlass nodes.
 235   const Type* klass_value_common(PhaseGVN* phase) const;
 236   Node* klass_identity_common(PhaseGVN* phase);
 237 
 238   virtual uint ideal_reg() const;
 239   virtual const Type *bottom_type() const;
 240   // Following method is copied from TypeNode:
 241   void set_type(const Type* t) {
 242     assert(t != NULL, "sanity");
 243     debug_only(uint check_hash = (VerifyHashTableKeys && _hash_lock) ? hash() : NO_HASH);
 244     *(const Type**)&_type = t;   // cast away const-ness
 245     // If this node is in the hash table, make sure it doesn't need a rehash.
 246     assert(check_hash == NO_HASH || check_hash == hash(), "type change must preserve hash code");
 247   }
 248   const Type* type() const { assert(_type != NULL, "sanity"); return _type; };
 249 
 250   // Do not match memory edge
 251   virtual uint match_edge(uint idx) const;
 252 
 253   // Map a load opcode to its corresponding store opcode.
 254   virtual int store_Opcode() const = 0;
 255 
 256   // Check if the load's memory input is a Phi node with the same control.
 257   bool is_instance_field_load_with_local_phi(Node* ctrl);
 258 
 259   Node* convert_to_unsigned_load(PhaseGVN& gvn);
 260   Node* convert_to_signed_load(PhaseGVN& gvn);
 261 
 262 #ifndef PRODUCT
 263   virtual void dump_spec(outputStream *st) const;
 264 #endif
 265 #ifdef ASSERT
 266   // Helper function to allow a raw load without control edge for some cases
 267   static bool is_immutable_value(Node* adr);
 268 #endif
 269 protected:
 270   const Type* load_array_final_field(const TypeKlassPtr *tkls,
 271                                      ciKlass* klass) const;
 272 
 273   Node* can_see_arraycopy_value(Node* st, PhaseGVN* phase) const;
 274 
 275   // depends_only_on_test is almost always true, and needs to be almost always
 276   // true to enable key hoisting & commoning optimizations.  However, for the
 277   // special case of RawPtr loads from TLS top & end, and other loads performed by
 278   // GC barriers, the control edge carries the dependence preventing hoisting past
 279   // a Safepoint instead of the memory edge.  (An unfortunate consequence of having
 280   // Safepoints not set Raw Memory; itself an unfortunate consequence of having Nodes
 281   // which produce results (new raw memory state) inside of loops preventing all
 282   // manner of other optimizations).  Basically, it's ugly but so is the alternative.
 283   // See comment in macro.cpp, around line 125 expand_allocate_common().
 284   virtual bool depends_only_on_test() const {
 285     return adr_type() != TypeRawPtr::BOTTOM && _control_dependency == DependsOnlyOnTest;
 286   }
 287 };
 288 
 289 //------------------------------LoadBNode--------------------------------------
 290 // Load a byte (8bits signed) from memory
 291 class LoadBNode : public LoadNode {
 292 public:
 293   LoadBNode(Node *c, Node *mem, Node *adr, const TypePtr* at, const TypeInt *ti, MemOrd mo, ControlDependency control_dependency = DependsOnlyOnTest)
 294     : LoadNode(c, mem, adr, at, ti, mo, control_dependency) {}
 295   virtual int Opcode() const;
 296   virtual uint ideal_reg() const { return Op_RegI; }
 297   virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
 298   virtual const Type* Value(PhaseGVN* phase) const;
 299   virtual int store_Opcode() const { return Op_StoreB; }
 300   virtual BasicType memory_type() const { return T_BYTE; }
 301 };
 302 
 303 //------------------------------LoadUBNode-------------------------------------
 304 // Load a unsigned byte (8bits unsigned) from memory
 305 class LoadUBNode : public LoadNode {
 306 public:
 307   LoadUBNode(Node* c, Node* mem, Node* adr, const TypePtr* at, const TypeInt* ti, MemOrd mo, ControlDependency control_dependency = DependsOnlyOnTest)
 308     : LoadNode(c, mem, adr, at, ti, mo, control_dependency) {}
 309   virtual int Opcode() const;
 310   virtual uint ideal_reg() const { return Op_RegI; }
 311   virtual Node* Ideal(PhaseGVN *phase, bool can_reshape);
 312   virtual const Type* Value(PhaseGVN* phase) const;
 313   virtual int store_Opcode() const { return Op_StoreB; }
 314   virtual BasicType memory_type() const { return T_BYTE; }
 315 };
 316 
 317 //------------------------------LoadUSNode-------------------------------------
 318 // Load an unsigned short/char (16bits unsigned) from memory
 319 class LoadUSNode : public LoadNode {
 320 public:
 321   LoadUSNode(Node *c, Node *mem, Node *adr, const TypePtr* at, const TypeInt *ti, MemOrd mo, ControlDependency control_dependency = DependsOnlyOnTest)
 322     : LoadNode(c, mem, adr, at, ti, mo, control_dependency) {}
 323   virtual int Opcode() const;
 324   virtual uint ideal_reg() const { return Op_RegI; }
 325   virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
 326   virtual const Type* Value(PhaseGVN* phase) const;
 327   virtual int store_Opcode() const { return Op_StoreC; }
 328   virtual BasicType memory_type() const { return T_CHAR; }
 329 };
 330 
 331 //------------------------------LoadSNode--------------------------------------
 332 // Load a short (16bits signed) from memory
 333 class LoadSNode : public LoadNode {
 334 public:
 335   LoadSNode(Node *c, Node *mem, Node *adr, const TypePtr* at, const TypeInt *ti, MemOrd mo, ControlDependency control_dependency = DependsOnlyOnTest)
 336     : LoadNode(c, mem, adr, at, ti, mo, control_dependency) {}
 337   virtual int Opcode() const;
 338   virtual uint ideal_reg() const { return Op_RegI; }
 339   virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
 340   virtual const Type* Value(PhaseGVN* phase) const;
 341   virtual int store_Opcode() const { return Op_StoreC; }
 342   virtual BasicType memory_type() const { return T_SHORT; }
 343 };
 344 
 345 //------------------------------LoadINode--------------------------------------
 346 // Load an integer from memory
 347 class LoadINode : public LoadNode {
 348 public:
 349   LoadINode(Node *c, Node *mem, Node *adr, const TypePtr* at, const TypeInt *ti, MemOrd mo, ControlDependency control_dependency = DependsOnlyOnTest)
 350     : LoadNode(c, mem, adr, at, ti, mo, control_dependency) {}
 351   virtual int Opcode() const;
 352   virtual uint ideal_reg() const { return Op_RegI; }
 353   virtual int store_Opcode() const { return Op_StoreI; }
 354   virtual BasicType memory_type() const { return T_INT; }
 355 };
 356 
 357 //------------------------------LoadRangeNode----------------------------------
 358 // Load an array length from the array
 359 class LoadRangeNode : public LoadINode {
 360 public:
 361   LoadRangeNode(Node *c, Node *mem, Node *adr, const TypeInt *ti = TypeInt::POS)
 362     : LoadINode(c, mem, adr, TypeAryPtr::RANGE, ti, MemNode::unordered) {}
 363   virtual int Opcode() const;
 364   virtual const Type* Value(PhaseGVN* phase) const;
 365   virtual Node* Identity(PhaseGVN* phase);
 366   virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
 367 };
 368 
 369 //------------------------------LoadLNode--------------------------------------
 370 // Load a long from memory
 371 class LoadLNode : public LoadNode {
 372   virtual uint hash() const { return LoadNode::hash() + _require_atomic_access; }
 373   virtual uint cmp( const Node &n ) const {
 374     return _require_atomic_access == ((LoadLNode&)n)._require_atomic_access
 375       && LoadNode::cmp(n);
 376   }
 377   virtual uint size_of() const { return sizeof(*this); }
 378   const bool _require_atomic_access;  // is piecewise load forbidden?
 379 
 380 public:
 381   LoadLNode(Node *c, Node *mem, Node *adr, const TypePtr* at, const TypeLong *tl,
 382             MemOrd mo, ControlDependency control_dependency = DependsOnlyOnTest, bool require_atomic_access = false)
 383     : LoadNode(c, mem, adr, at, tl, mo, control_dependency), _require_atomic_access(require_atomic_access) {}
 384   virtual int Opcode() const;
 385   virtual uint ideal_reg() const { return Op_RegL; }
 386   virtual int store_Opcode() const { return Op_StoreL; }
 387   virtual BasicType memory_type() const { return T_LONG; }
 388   bool require_atomic_access() const { return _require_atomic_access; }
 389   static LoadLNode* make_atomic(Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type,
 390                                 const Type* rt, MemOrd mo, ControlDependency control_dependency = DependsOnlyOnTest,
 391                                 bool unaligned = false, bool mismatched = false);
 392 #ifndef PRODUCT
 393   virtual void dump_spec(outputStream *st) const {
 394     LoadNode::dump_spec(st);
 395     if (_require_atomic_access)  st->print(" Atomic!");
 396   }
 397 #endif
 398 };
 399 
 400 //------------------------------LoadL_unalignedNode----------------------------
 401 // Load a long from unaligned memory
 402 class LoadL_unalignedNode : public LoadLNode {
 403 public:
 404   LoadL_unalignedNode(Node *c, Node *mem, Node *adr, const TypePtr* at, MemOrd mo, ControlDependency control_dependency = DependsOnlyOnTest)
 405     : LoadLNode(c, mem, adr, at, TypeLong::LONG, mo, control_dependency) {}
 406   virtual int Opcode() const;
 407 };
 408 
 409 //------------------------------LoadFNode--------------------------------------
 410 // Load a float (64 bits) from memory
 411 class LoadFNode : public LoadNode {
 412 public:
 413   LoadFNode(Node *c, Node *mem, Node *adr, const TypePtr* at, const Type *t, MemOrd mo, ControlDependency control_dependency = DependsOnlyOnTest)
 414     : LoadNode(c, mem, adr, at, t, mo, control_dependency) {}
 415   virtual int Opcode() const;
 416   virtual uint ideal_reg() const { return Op_RegF; }
 417   virtual int store_Opcode() const { return Op_StoreF; }
 418   virtual BasicType memory_type() const { return T_FLOAT; }
 419 };
 420 
 421 //------------------------------LoadDNode--------------------------------------
 422 // Load a double (64 bits) from memory
 423 class LoadDNode : public LoadNode {
 424   virtual uint hash() const { return LoadNode::hash() + _require_atomic_access; }
 425   virtual uint cmp( const Node &n ) const {
 426     return _require_atomic_access == ((LoadDNode&)n)._require_atomic_access
 427       && LoadNode::cmp(n);
 428   }
 429   virtual uint size_of() const { return sizeof(*this); }
 430   const bool _require_atomic_access;  // is piecewise load forbidden?
 431 
 432 public:
 433   LoadDNode(Node *c, Node *mem, Node *adr, const TypePtr* at, const Type *t,
 434             MemOrd mo, ControlDependency control_dependency = DependsOnlyOnTest, bool require_atomic_access = false)
 435     : LoadNode(c, mem, adr, at, t, mo, control_dependency), _require_atomic_access(require_atomic_access) {}
 436   virtual int Opcode() const;
 437   virtual uint ideal_reg() const { return Op_RegD; }
 438   virtual int store_Opcode() const { return Op_StoreD; }
 439   virtual BasicType memory_type() const { return T_DOUBLE; }
 440   bool require_atomic_access() const { return _require_atomic_access; }
 441   static LoadDNode* make_atomic(Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type,
 442                                 const Type* rt, MemOrd mo, ControlDependency control_dependency = DependsOnlyOnTest,
 443                                 bool unaligned = false, bool mismatched = false);
 444 #ifndef PRODUCT
 445   virtual void dump_spec(outputStream *st) const {
 446     LoadNode::dump_spec(st);
 447     if (_require_atomic_access)  st->print(" Atomic!");
 448   }
 449 #endif
 450 };
 451 
 452 //------------------------------LoadD_unalignedNode----------------------------
 453 // Load a double from unaligned memory
 454 class LoadD_unalignedNode : public LoadDNode {
 455 public:
 456   LoadD_unalignedNode(Node *c, Node *mem, Node *adr, const TypePtr* at, MemOrd mo, ControlDependency control_dependency = DependsOnlyOnTest)
 457     : LoadDNode(c, mem, adr, at, Type::DOUBLE, mo, control_dependency) {}
 458   virtual int Opcode() const;
 459 };
 460 
 461 //------------------------------LoadPNode--------------------------------------
 462 // Load a pointer from memory (either object or array)
 463 class LoadPNode : public LoadNode {
 464 public:
 465   LoadPNode(Node *c, Node *mem, Node *adr, const TypePtr *at, const TypePtr* t, MemOrd mo, ControlDependency control_dependency = DependsOnlyOnTest)
 466     : LoadNode(c, mem, adr, at, t, mo, control_dependency) {}
 467   virtual int Opcode() const;
 468   virtual uint ideal_reg() const { return Op_RegP; }
 469   virtual int store_Opcode() const { return Op_StoreP; }
 470   virtual BasicType memory_type() const { return T_ADDRESS; }
 471 };
 472 
 473 
 474 //------------------------------LoadNNode--------------------------------------
 475 // Load a narrow oop from memory (either object or array)
 476 class LoadNNode : public LoadNode {
 477 public:
 478   LoadNNode(Node *c, Node *mem, Node *adr, const TypePtr *at, const Type* t, MemOrd mo, ControlDependency control_dependency = DependsOnlyOnTest)
 479     : LoadNode(c, mem, adr, at, t, mo, control_dependency) {}
 480   virtual int Opcode() const;
 481   virtual uint ideal_reg() const { return Op_RegN; }
 482   virtual int store_Opcode() const { return Op_StoreN; }
 483   virtual BasicType memory_type() const { return T_NARROWOOP; }
 484 };
 485 
 486 //------------------------------LoadKlassNode----------------------------------
 487 // Load a Klass from an object
 488 class LoadKlassNode : public LoadPNode {
 489 protected:
 490   // In most cases, LoadKlassNode does not have the control input set. If the control
 491   // input is set, it must not be removed (by LoadNode::Ideal()).
 492   virtual bool can_remove_control() const;
 493 public:
 494   LoadKlassNode(Node *c, Node *mem, Node *adr, const TypePtr *at, const TypeKlassPtr *tk, MemOrd mo)
 495     : LoadPNode(c, mem, adr, at, tk, mo) {}
 496   virtual int Opcode() const;
 497   virtual const Type* Value(PhaseGVN* phase) const;
 498   virtual Node* Identity(PhaseGVN* phase);
 499   virtual bool depends_only_on_test() const { return true; }
 500 
 501   // Polymorphic factory method:
 502   static Node* make(PhaseGVN& gvn, Node* ctl, Node* mem, Node* adr, const TypePtr* at,
 503                     const TypeKlassPtr* tk = TypeKlassPtr::OBJECT);
 504 };
 505 
 506 //------------------------------LoadNKlassNode---------------------------------
 507 // Load a narrow Klass from an object.
 508 class LoadNKlassNode : public LoadNNode {
 509 public:
 510   LoadNKlassNode(Node *c, Node *mem, Node *adr, const TypePtr *at, const TypeNarrowKlass *tk, MemOrd mo)
 511     : LoadNNode(c, mem, adr, at, tk, mo) {}
 512   virtual int Opcode() const;
 513   virtual uint ideal_reg() const { return Op_RegN; }
 514   virtual int store_Opcode() const { return Op_StoreNKlass; }
 515   virtual BasicType memory_type() const { return T_NARROWKLASS; }
 516 
 517   virtual const Type* Value(PhaseGVN* phase) const;
 518   virtual Node* Identity(PhaseGVN* phase);
 519   virtual bool depends_only_on_test() const { return true; }
 520 };
 521 
 522 
 523 //------------------------------StoreNode--------------------------------------
 524 // Store value; requires Store, Address and Value
 525 class StoreNode : public MemNode {
 526 private:
 527   // On platforms with weak memory ordering (e.g., PPC, Ia64) we distinguish
 528   // stores that can be reordered, and such requiring release semantics to
 529   // adhere to the Java specification.  The required behaviour is stored in
 530   // this field.
 531   const MemOrd _mo;
 532   // Needed for proper cloning.
 533   virtual uint size_of() const { return sizeof(*this); }
 534 protected:
 535   virtual uint cmp( const Node &n ) const;
 536   virtual bool depends_only_on_test() const { return false; }
 537 
 538   Node *Ideal_masked_input       (PhaseGVN *phase, uint mask);
 539   Node *Ideal_sign_extended_input(PhaseGVN *phase, int  num_bits);
 540 
 541 public:
 542   // We must ensure that stores of object references will be visible
 543   // only after the object's initialization. So the callers of this
 544   // procedure must indicate that the store requires `release'
 545   // semantics, if the stored value is an object reference that might
 546   // point to a new object and may become externally visible.
 547   StoreNode(Node *c, Node *mem, Node *adr, const TypePtr* at, Node *val, MemOrd mo)
 548     : MemNode(c, mem, adr, at, val), _mo(mo) {
 549     init_class_id(Class_Store);
 550   }
 551   StoreNode(Node *c, Node *mem, Node *adr, const TypePtr* at, Node *val, Node *oop_store, MemOrd mo)
 552     : MemNode(c, mem, adr, at, val, oop_store), _mo(mo) {
 553     init_class_id(Class_Store);
 554   }
 555 
 556   inline bool is_unordered() const { return !is_release(); }
 557   inline bool is_release() const {
 558     assert((_mo == unordered || _mo == release), "unexpected");
 559     return _mo == release;
 560   }
 561 
 562   // Conservatively release stores of object references in order to
 563   // ensure visibility of object initialization.
 564   static inline MemOrd release_if_reference(const BasicType t) {
 565 #ifdef AARCH64
 566     // AArch64 doesn't need a release store here because object
 567     // initialization contains the necessary barriers.
 568     return unordered;
 569 #else
 570     const MemOrd mo = (t == T_ARRAY ||
 571                        t == T_ADDRESS || // Might be the address of an object reference (`boxing').
 572                        t == T_OBJECT) ? release : unordered;
 573     return mo;
 574 #endif
 575   }
 576 
 577   // Polymorphic factory method
 578   //
 579   // We must ensure that stores of object references will be visible
 580   // only after the object's initialization. So the callers of this
 581   // procedure must indicate that the store requires `release'
 582   // semantics, if the stored value is an object reference that might
 583   // point to a new object and may become externally visible.
 584   static StoreNode* make(PhaseGVN& gvn, Node *c, Node *mem, Node *adr,
 585                          const TypePtr* at, Node *val, BasicType bt, MemOrd mo);
 586 
 587   virtual uint hash() const;    // Check the type
 588 
 589   // If the store is to Field memory and the pointer is non-null, we can
 590   // zero out the control input.
 591   virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
 592 
 593   // Compute a new Type for this node.  Basically we just do the pre-check,
 594   // then call the virtual add() to set the type.
 595   virtual const Type* Value(PhaseGVN* phase) const;
 596 
 597   // Check for identity function on memory (Load then Store at same address)
 598   virtual Node* Identity(PhaseGVN* phase);
 599 
 600   // Do not match memory edge
 601   virtual uint match_edge(uint idx) const;
 602 
 603   virtual const Type *bottom_type() const;  // returns Type::MEMORY
 604 
 605   // Map a store opcode to its corresponding own opcode, trivially.
 606   virtual int store_Opcode() const { return Opcode(); }
 607 
 608   // have all possible loads of the value stored been optimized away?
 609   bool value_never_loaded(PhaseTransform *phase) const;
 610 };
 611 
 612 //------------------------------StoreBNode-------------------------------------
 613 // Store byte to memory
 614 class StoreBNode : public StoreNode {
 615 public:
 616   StoreBNode(Node *c, Node *mem, Node *adr, const TypePtr* at, Node *val, MemOrd mo)
 617     : StoreNode(c, mem, adr, at, val, mo) {}
 618   virtual int Opcode() const;
 619   virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
 620   virtual BasicType memory_type() const { return T_BYTE; }
 621 };
 622 
 623 //------------------------------StoreCNode-------------------------------------
 624 // Store char/short to memory
 625 class StoreCNode : public StoreNode {
 626 public:
 627   StoreCNode(Node *c, Node *mem, Node *adr, const TypePtr* at, Node *val, MemOrd mo)
 628     : StoreNode(c, mem, adr, at, val, mo) {}
 629   virtual int Opcode() const;
 630   virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
 631   virtual BasicType memory_type() const { return T_CHAR; }
 632 };
 633 
 634 //------------------------------StoreINode-------------------------------------
 635 // Store int to memory
 636 class StoreINode : public StoreNode {
 637 public:
 638   StoreINode(Node *c, Node *mem, Node *adr, const TypePtr* at, Node *val, MemOrd mo)
 639     : StoreNode(c, mem, adr, at, val, mo) {}
 640   virtual int Opcode() const;
 641   virtual BasicType memory_type() const { return T_INT; }
 642 };
 643 
 644 //------------------------------StoreLNode-------------------------------------
 645 // Store long to memory
 646 class StoreLNode : public StoreNode {
 647   virtual uint hash() const { return StoreNode::hash() + _require_atomic_access; }
 648   virtual uint cmp( const Node &n ) const {
 649     return _require_atomic_access == ((StoreLNode&)n)._require_atomic_access
 650       && StoreNode::cmp(n);
 651   }
 652   virtual uint size_of() const { return sizeof(*this); }
 653   const bool _require_atomic_access;  // is piecewise store forbidden?
 654 
 655 public:
 656   StoreLNode(Node *c, Node *mem, Node *adr, const TypePtr* at, Node *val, MemOrd mo, bool require_atomic_access = false)
 657     : StoreNode(c, mem, adr, at, val, mo), _require_atomic_access(require_atomic_access) {}
 658   virtual int Opcode() const;
 659   virtual BasicType memory_type() const { return T_LONG; }
 660   bool require_atomic_access() const { return _require_atomic_access; }
 661   static StoreLNode* make_atomic(Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, MemOrd mo);
 662 #ifndef PRODUCT
 663   virtual void dump_spec(outputStream *st) const {
 664     StoreNode::dump_spec(st);
 665     if (_require_atomic_access)  st->print(" Atomic!");
 666   }
 667 #endif
 668 };
 669 
 670 //------------------------------StoreFNode-------------------------------------
 671 // Store float to memory
 672 class StoreFNode : public StoreNode {
 673 public:
 674   StoreFNode(Node *c, Node *mem, Node *adr, const TypePtr* at, Node *val, MemOrd mo)
 675     : StoreNode(c, mem, adr, at, val, mo) {}
 676   virtual int Opcode() const;
 677   virtual BasicType memory_type() const { return T_FLOAT; }
 678 };
 679 
 680 //------------------------------StoreDNode-------------------------------------
 681 // Store double to memory
 682 class StoreDNode : public StoreNode {
 683   virtual uint hash() const { return StoreNode::hash() + _require_atomic_access; }
 684   virtual uint cmp( const Node &n ) const {
 685     return _require_atomic_access == ((StoreDNode&)n)._require_atomic_access
 686       && StoreNode::cmp(n);
 687   }
 688   virtual uint size_of() const { return sizeof(*this); }
 689   const bool _require_atomic_access;  // is piecewise store forbidden?
 690 public:
 691   StoreDNode(Node *c, Node *mem, Node *adr, const TypePtr* at, Node *val,
 692              MemOrd mo, bool require_atomic_access = false)
 693     : StoreNode(c, mem, adr, at, val, mo), _require_atomic_access(require_atomic_access) {}
 694   virtual int Opcode() const;
 695   virtual BasicType memory_type() const { return T_DOUBLE; }
 696   bool require_atomic_access() const { return _require_atomic_access; }
 697   static StoreDNode* make_atomic(Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, MemOrd mo);
 698 #ifndef PRODUCT
 699   virtual void dump_spec(outputStream *st) const {
 700     StoreNode::dump_spec(st);
 701     if (_require_atomic_access)  st->print(" Atomic!");
 702   }
 703 #endif
 704 
 705 };
 706 
 707 //------------------------------StorePNode-------------------------------------
 708 // Store pointer to memory
 709 class StorePNode : public StoreNode {
 710 public:
 711   StorePNode(Node *c, Node *mem, Node *adr, const TypePtr* at, Node *val, MemOrd mo)
 712     : StoreNode(c, mem, adr, at, val, mo) {}
 713   virtual int Opcode() const;
 714   virtual BasicType memory_type() const { return T_ADDRESS; }
 715 };
 716 
 717 //------------------------------StoreNNode-------------------------------------
 718 // Store narrow oop to memory
 719 class StoreNNode : public StoreNode {
 720 public:
 721   StoreNNode(Node *c, Node *mem, Node *adr, const TypePtr* at, Node *val, MemOrd mo)
 722     : StoreNode(c, mem, adr, at, val, mo) {}
 723   virtual int Opcode() const;
 724   virtual BasicType memory_type() const { return T_NARROWOOP; }
 725 };
 726 
 727 //------------------------------StoreNKlassNode--------------------------------------
 728 // Store narrow klass to memory
 729 class StoreNKlassNode : public StoreNNode {
 730 public:
 731   StoreNKlassNode(Node *c, Node *mem, Node *adr, const TypePtr* at, Node *val, MemOrd mo)
 732     : StoreNNode(c, mem, adr, at, val, mo) {}
 733   virtual int Opcode() const;
 734   virtual BasicType memory_type() const { return T_NARROWKLASS; }
 735 };
 736 
 737 //------------------------------StoreCMNode-----------------------------------
 738 // Store card-mark byte to memory for CM
 739 // The last StoreCM before a SafePoint must be preserved and occur after its "oop" store
 740 // Preceeding equivalent StoreCMs may be eliminated.
 741 class StoreCMNode : public StoreNode {
 742  private:
 743   virtual uint hash() const { return StoreNode::hash() + _oop_alias_idx; }
 744   virtual uint cmp( const Node &n ) const {
 745     return _oop_alias_idx == ((StoreCMNode&)n)._oop_alias_idx
 746       && StoreNode::cmp(n);
 747   }
 748   virtual uint size_of() const { return sizeof(*this); }
 749   int _oop_alias_idx;   // The alias_idx of OopStore
 750 
 751 public:
 752   StoreCMNode( Node *c, Node *mem, Node *adr, const TypePtr* at, Node *val, Node *oop_store, int oop_alias_idx ) :
 753     StoreNode(c, mem, adr, at, val, oop_store, MemNode::release),
 754     _oop_alias_idx(oop_alias_idx) {
 755     assert(_oop_alias_idx >= Compile::AliasIdxRaw ||
 756            _oop_alias_idx == Compile::AliasIdxBot && Compile::current()->AliasLevel() == 0,
 757            "bad oop alias idx");
 758   }
 759   virtual int Opcode() const;
 760   virtual Node* Identity(PhaseGVN* phase);
 761   virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
 762   virtual const Type* Value(PhaseGVN* phase) const;
 763   virtual BasicType memory_type() const { return T_VOID; } // unspecific
 764   int oop_alias_idx() const { return _oop_alias_idx; }
 765 };
 766 
 767 //------------------------------LoadPLockedNode---------------------------------
 768 // Load-locked a pointer from memory (either object or array).
 769 // On Sparc & Intel this is implemented as a normal pointer load.
 770 // On PowerPC and friends it's a real load-locked.
 771 class LoadPLockedNode : public LoadPNode {
 772 public:
 773   LoadPLockedNode(Node *c, Node *mem, Node *adr, MemOrd mo)
 774     : LoadPNode(c, mem, adr, TypeRawPtr::BOTTOM, TypeRawPtr::BOTTOM, mo) {}
 775   virtual int Opcode() const;
 776   virtual int store_Opcode() const { return Op_StorePConditional; }
 777   virtual bool depends_only_on_test() const { return true; }
 778 };
 779 
 780 //------------------------------SCMemProjNode---------------------------------------
 781 // This class defines a projection of the memory  state of a store conditional node.
 782 // These nodes return a value, but also update memory.
 783 class SCMemProjNode : public ProjNode {
 784 public:
 785   enum {SCMEMPROJCON = (uint)-2};
 786   SCMemProjNode( Node *src) : ProjNode( src, SCMEMPROJCON) { }
 787   virtual int Opcode() const;
 788   virtual bool      is_CFG() const  { return false; }
 789   virtual const Type *bottom_type() const {return Type::MEMORY;}
 790   virtual const TypePtr *adr_type() const {
 791     Node* ctrl = in(0);
 792     if (ctrl == NULL)  return NULL; // node is dead
 793     return ctrl->in(MemNode::Memory)->adr_type();
 794   }
 795   virtual uint ideal_reg() const { return 0;} // memory projections don't have a register
 796   virtual const Type* Value(PhaseGVN* phase) const;
 797 #ifndef PRODUCT
 798   virtual void dump_spec(outputStream *st) const {};
 799 #endif
 800 };
 801 
 802 //------------------------------LoadStoreNode---------------------------
 803 // Note: is_Mem() method returns 'true' for this class.
 804 class LoadStoreNode : public Node {
 805 private:
 806   const Type* const _type;      // What kind of value is loaded?
 807   const TypePtr* _adr_type;     // What kind of memory is being addressed?
 808   virtual uint size_of() const; // Size is bigger
 809 public:
 810   LoadStoreNode( Node *c, Node *mem, Node *adr, Node *val, const TypePtr* at, const Type* rt, uint required );
 811   virtual bool depends_only_on_test() const { return false; }
 812   virtual uint match_edge(uint idx) const { return idx == MemNode::Address || idx == MemNode::ValueIn; }
 813 
 814   virtual const Type *bottom_type() const { return _type; }
 815   virtual uint ideal_reg() const;
 816   virtual const class TypePtr *adr_type() const { return _adr_type; }  // returns bottom_type of address
 817 
 818   bool result_not_used() const;
 819 };
 820 
 821 class LoadStoreConditionalNode : public LoadStoreNode {
 822 public:
 823   enum {
 824     ExpectedIn = MemNode::ValueIn+1 // One more input than MemNode
 825   };
 826   LoadStoreConditionalNode(Node *c, Node *mem, Node *adr, Node *val, Node *ex);
 827 };
 828 
 829 //------------------------------StorePConditionalNode---------------------------
 830 // Conditionally store pointer to memory, if no change since prior
 831 // load-locked.  Sets flags for success or failure of the store.
 832 class StorePConditionalNode : public LoadStoreConditionalNode {
 833 public:
 834   StorePConditionalNode( Node *c, Node *mem, Node *adr, Node *val, Node *ll ) : LoadStoreConditionalNode(c, mem, adr, val, ll) { }
 835   virtual int Opcode() const;
 836   // Produces flags
 837   virtual uint ideal_reg() const { return Op_RegFlags; }
 838 };
 839 
 840 //------------------------------StoreIConditionalNode---------------------------
 841 // Conditionally store int to memory, if no change since prior
 842 // load-locked.  Sets flags for success or failure of the store.
 843 class StoreIConditionalNode : public LoadStoreConditionalNode {
 844 public:
 845   StoreIConditionalNode( Node *c, Node *mem, Node *adr, Node *val, Node *ii ) : LoadStoreConditionalNode(c, mem, adr, val, ii) { }
 846   virtual int Opcode() const;
 847   // Produces flags
 848   virtual uint ideal_reg() const { return Op_RegFlags; }
 849 };
 850 
 851 //------------------------------StoreLConditionalNode---------------------------
 852 // Conditionally store long to memory, if no change since prior
 853 // load-locked.  Sets flags for success or failure of the store.
 854 class StoreLConditionalNode : public LoadStoreConditionalNode {
 855 public:
 856   StoreLConditionalNode( Node *c, Node *mem, Node *adr, Node *val, Node *ll ) : LoadStoreConditionalNode(c, mem, adr, val, ll) { }
 857   virtual int Opcode() const;
 858   // Produces flags
 859   virtual uint ideal_reg() const { return Op_RegFlags; }
 860 };
 861 
 862 class CompareAndSwapNode : public LoadStoreConditionalNode {
 863 private:
 864   const MemNode::MemOrd _mem_ord;
 865 public:
 866   CompareAndSwapNode( Node *c, Node *mem, Node *adr, Node *val, Node *ex, MemNode::MemOrd mem_ord) : LoadStoreConditionalNode(c, mem, adr, val, ex), _mem_ord(mem_ord) {}
 867   MemNode::MemOrd order() const {
 868     return _mem_ord;
 869   }
 870 };
 871 
 872 class CompareAndExchangeNode : public LoadStoreNode {
 873 private:
 874   const MemNode::MemOrd _mem_ord;
 875 public:
 876   enum {
 877     ExpectedIn = MemNode::ValueIn+1 // One more input than MemNode
 878   };
 879   CompareAndExchangeNode( Node *c, Node *mem, Node *adr, Node *val, Node *ex, MemNode::MemOrd mem_ord, const TypePtr* at, const Type* t) :
 880     LoadStoreNode(c, mem, adr, val, at, t, 5), _mem_ord(mem_ord) {
 881      init_req(ExpectedIn, ex );
 882   }
 883 
 884   MemNode::MemOrd order() const {
 885     return _mem_ord;
 886   }
 887 };
 888 
 889 //------------------------------CompareAndSwapBNode---------------------------
 890 class CompareAndSwapBNode : public CompareAndSwapNode {
 891 public:
 892   CompareAndSwapBNode( Node *c, Node *mem, Node *adr, Node *val, Node *ex, MemNode::MemOrd mem_ord) : CompareAndSwapNode(c, mem, adr, val, ex, mem_ord) { }
 893   virtual int Opcode() const;
 894 };
 895 
 896 //------------------------------CompareAndSwapSNode---------------------------
 897 class CompareAndSwapSNode : public CompareAndSwapNode {
 898 public:
 899   CompareAndSwapSNode( Node *c, Node *mem, Node *adr, Node *val, Node *ex, MemNode::MemOrd mem_ord) : CompareAndSwapNode(c, mem, adr, val, ex, mem_ord) { }
 900   virtual int Opcode() const;
 901 };
 902 
 903 //------------------------------CompareAndSwapINode---------------------------
 904 class CompareAndSwapINode : public CompareAndSwapNode {
 905 public:
 906   CompareAndSwapINode( Node *c, Node *mem, Node *adr, Node *val, Node *ex, MemNode::MemOrd mem_ord) : CompareAndSwapNode(c, mem, adr, val, ex, mem_ord) { }
 907   virtual int Opcode() const;
 908 };
 909 
 910 //------------------------------CompareAndSwapLNode---------------------------
 911 class CompareAndSwapLNode : public CompareAndSwapNode {
 912 public:
 913   CompareAndSwapLNode( Node *c, Node *mem, Node *adr, Node *val, Node *ex, MemNode::MemOrd mem_ord) : CompareAndSwapNode(c, mem, adr, val, ex, mem_ord) { }
 914   virtual int Opcode() const;
 915 };
 916 
 917 //------------------------------CompareAndSwapPNode---------------------------
 918 class CompareAndSwapPNode : public CompareAndSwapNode {
 919 public:
 920   CompareAndSwapPNode( Node *c, Node *mem, Node *adr, Node *val, Node *ex, MemNode::MemOrd mem_ord) : CompareAndSwapNode(c, mem, adr, val, ex, mem_ord) { }
 921   virtual int Opcode() const;
 922 };
 923 
 924 //------------------------------CompareAndSwapNNode---------------------------
 925 class CompareAndSwapNNode : public CompareAndSwapNode {
 926 public:
 927   CompareAndSwapNNode( Node *c, Node *mem, Node *adr, Node *val, Node *ex, MemNode::MemOrd mem_ord) : CompareAndSwapNode(c, mem, adr, val, ex, mem_ord) { }
 928   virtual int Opcode() const;
 929 };
 930 
 931 //------------------------------WeakCompareAndSwapBNode---------------------------
 932 class WeakCompareAndSwapBNode : public CompareAndSwapNode {
 933 public:
 934   WeakCompareAndSwapBNode( Node *c, Node *mem, Node *adr, Node *val, Node *ex, MemNode::MemOrd mem_ord) : CompareAndSwapNode(c, mem, adr, val, ex, mem_ord) { }
 935   virtual int Opcode() const;
 936 };
 937 
 938 //------------------------------WeakCompareAndSwapSNode---------------------------
 939 class WeakCompareAndSwapSNode : public CompareAndSwapNode {
 940 public:
 941   WeakCompareAndSwapSNode( Node *c, Node *mem, Node *adr, Node *val, Node *ex, MemNode::MemOrd mem_ord) : CompareAndSwapNode(c, mem, adr, val, ex, mem_ord) { }
 942   virtual int Opcode() const;
 943 };
 944 
 945 //------------------------------WeakCompareAndSwapINode---------------------------
 946 class WeakCompareAndSwapINode : public CompareAndSwapNode {
 947 public:
 948   WeakCompareAndSwapINode( Node *c, Node *mem, Node *adr, Node *val, Node *ex, MemNode::MemOrd mem_ord) : CompareAndSwapNode(c, mem, adr, val, ex, mem_ord) { }
 949   virtual int Opcode() const;
 950 };
 951 
 952 //------------------------------WeakCompareAndSwapLNode---------------------------
 953 class WeakCompareAndSwapLNode : public CompareAndSwapNode {
 954 public:
 955   WeakCompareAndSwapLNode( Node *c, Node *mem, Node *adr, Node *val, Node *ex, MemNode::MemOrd mem_ord) : CompareAndSwapNode(c, mem, adr, val, ex, mem_ord) { }
 956   virtual int Opcode() const;
 957 };
 958 
 959 //------------------------------WeakCompareAndSwapPNode---------------------------
 960 class WeakCompareAndSwapPNode : public CompareAndSwapNode {
 961 public:
 962   WeakCompareAndSwapPNode( Node *c, Node *mem, Node *adr, Node *val, Node *ex, MemNode::MemOrd mem_ord) : CompareAndSwapNode(c, mem, adr, val, ex, mem_ord) { }
 963   virtual int Opcode() const;
 964 };
 965 
 966 //------------------------------WeakCompareAndSwapNNode---------------------------
 967 class WeakCompareAndSwapNNode : public CompareAndSwapNode {
 968 public:
 969   WeakCompareAndSwapNNode( Node *c, Node *mem, Node *adr, Node *val, Node *ex, MemNode::MemOrd mem_ord) : CompareAndSwapNode(c, mem, adr, val, ex, mem_ord) { }
 970   virtual int Opcode() const;
 971 };
 972 
 973 //------------------------------CompareAndExchangeBNode---------------------------
 974 class CompareAndExchangeBNode : public CompareAndExchangeNode {
 975 public:
 976   CompareAndExchangeBNode( Node *c, Node *mem, Node *adr, Node *val, Node *ex, const TypePtr* at, MemNode::MemOrd mem_ord) : CompareAndExchangeNode(c, mem, adr, val, ex, mem_ord, at, TypeInt::BYTE) { }
 977   virtual int Opcode() const;
 978 };
 979 
 980 
 981 //------------------------------CompareAndExchangeSNode---------------------------
 982 class CompareAndExchangeSNode : public CompareAndExchangeNode {
 983 public:
 984   CompareAndExchangeSNode( Node *c, Node *mem, Node *adr, Node *val, Node *ex, const TypePtr* at, MemNode::MemOrd mem_ord) : CompareAndExchangeNode(c, mem, adr, val, ex, mem_ord, at, TypeInt::SHORT) { }
 985   virtual int Opcode() const;
 986 };
 987 
 988 //------------------------------CompareAndExchangeLNode---------------------------
 989 class CompareAndExchangeLNode : public CompareAndExchangeNode {
 990 public:
 991   CompareAndExchangeLNode( Node *c, Node *mem, Node *adr, Node *val, Node *ex, const TypePtr* at, MemNode::MemOrd mem_ord) : CompareAndExchangeNode(c, mem, adr, val, ex, mem_ord, at, TypeLong::LONG) { }
 992   virtual int Opcode() const;
 993 };
 994 
 995 
 996 //------------------------------CompareAndExchangeINode---------------------------
 997 class CompareAndExchangeINode : public CompareAndExchangeNode {
 998 public:
 999   CompareAndExchangeINode( Node *c, Node *mem, Node *adr, Node *val, Node *ex, const TypePtr* at, MemNode::MemOrd mem_ord) : CompareAndExchangeNode(c, mem, adr, val, ex, mem_ord, at, TypeInt::INT) { }
1000   virtual int Opcode() const;
1001 };
1002 
1003 
1004 //------------------------------CompareAndExchangePNode---------------------------
1005 class CompareAndExchangePNode : public CompareAndExchangeNode {
1006 public:
1007   CompareAndExchangePNode( Node *c, Node *mem, Node *adr, Node *val, Node *ex, const TypePtr* at, const Type* t, MemNode::MemOrd mem_ord) : CompareAndExchangeNode(c, mem, adr, val, ex, mem_ord, at, t) { }
1008   virtual int Opcode() const;
1009 };
1010 
1011 //------------------------------CompareAndExchangeNNode---------------------------
1012 class CompareAndExchangeNNode : public CompareAndExchangeNode {
1013 public:
1014   CompareAndExchangeNNode( Node *c, Node *mem, Node *adr, Node *val, Node *ex, const TypePtr* at, const Type* t, MemNode::MemOrd mem_ord) : CompareAndExchangeNode(c, mem, adr, val, ex, mem_ord, at, t) { }
1015   virtual int Opcode() const;
1016 };
1017 
1018 //------------------------------GetAndAddBNode---------------------------
1019 class GetAndAddBNode : public LoadStoreNode {
1020 public:
1021   GetAndAddBNode( Node *c, Node *mem, Node *adr, Node *val, const TypePtr* at ) : LoadStoreNode(c, mem, adr, val, at, TypeInt::BYTE, 4) { }
1022   virtual int Opcode() const;
1023 };
1024 
1025 //------------------------------GetAndAddSNode---------------------------
1026 class GetAndAddSNode : public LoadStoreNode {
1027 public:
1028   GetAndAddSNode( Node *c, Node *mem, Node *adr, Node *val, const TypePtr* at ) : LoadStoreNode(c, mem, adr, val, at, TypeInt::SHORT, 4) { }
1029   virtual int Opcode() const;
1030 };
1031 
1032 //------------------------------GetAndAddINode---------------------------
1033 class GetAndAddINode : public LoadStoreNode {
1034 public:
1035   GetAndAddINode( Node *c, Node *mem, Node *adr, Node *val, const TypePtr* at ) : LoadStoreNode(c, mem, adr, val, at, TypeInt::INT, 4) { }
1036   virtual int Opcode() const;
1037 };
1038 
1039 //------------------------------GetAndAddLNode---------------------------
1040 class GetAndAddLNode : public LoadStoreNode {
1041 public:
1042   GetAndAddLNode( Node *c, Node *mem, Node *adr, Node *val, const TypePtr* at ) : LoadStoreNode(c, mem, adr, val, at, TypeLong::LONG, 4) { }
1043   virtual int Opcode() const;
1044 };
1045 
1046 //------------------------------GetAndSetBNode---------------------------
1047 class GetAndSetBNode : public LoadStoreNode {
1048 public:
1049   GetAndSetBNode( Node *c, Node *mem, Node *adr, Node *val, const TypePtr* at ) : LoadStoreNode(c, mem, adr, val, at, TypeInt::BYTE, 4) { }
1050   virtual int Opcode() const;
1051 };
1052 
1053 //------------------------------GetAndSetSNode---------------------------
1054 class GetAndSetSNode : public LoadStoreNode {
1055 public:
1056   GetAndSetSNode( Node *c, Node *mem, Node *adr, Node *val, const TypePtr* at ) : LoadStoreNode(c, mem, adr, val, at, TypeInt::SHORT, 4) { }
1057   virtual int Opcode() const;
1058 };
1059 
1060 //------------------------------GetAndSetINode---------------------------
1061 class GetAndSetINode : public LoadStoreNode {
1062 public:
1063   GetAndSetINode( Node *c, Node *mem, Node *adr, Node *val, const TypePtr* at ) : LoadStoreNode(c, mem, adr, val, at, TypeInt::INT, 4) { }
1064   virtual int Opcode() const;
1065 };
1066 
1067 //------------------------------GetAndSetLNode---------------------------
1068 class GetAndSetLNode : public LoadStoreNode {
1069 public:
1070   GetAndSetLNode( Node *c, Node *mem, Node *adr, Node *val, const TypePtr* at ) : LoadStoreNode(c, mem, adr, val, at, TypeLong::LONG, 4) { }
1071   virtual int Opcode() const;
1072 };
1073 
1074 //------------------------------GetAndSetPNode---------------------------
1075 class GetAndSetPNode : public LoadStoreNode {
1076 public:
1077   GetAndSetPNode( Node *c, Node *mem, Node *adr, Node *val, const TypePtr* at, const Type* t ) : LoadStoreNode(c, mem, adr, val, at, t, 4) { }
1078   virtual int Opcode() const;
1079 };
1080 
1081 //------------------------------GetAndSetNNode---------------------------
1082 class GetAndSetNNode : public LoadStoreNode {
1083 public:
1084   GetAndSetNNode( Node *c, Node *mem, Node *adr, Node *val, const TypePtr* at, const Type* t ) : LoadStoreNode(c, mem, adr, val, at, t, 4) { }
1085   virtual int Opcode() const;
1086 };
1087 
1088 //------------------------------ClearArray-------------------------------------
1089 class ClearArrayNode: public Node {
1090 private:
1091   bool _is_large;
1092 public:
1093   ClearArrayNode( Node *ctrl, Node *arymem, Node *word_cnt, Node *base, bool is_large)
1094     : Node(ctrl,arymem,word_cnt,base), _is_large(is_large) {
1095     init_class_id(Class_ClearArray);
1096   }
1097   virtual int         Opcode() const;
1098   virtual const Type *bottom_type() const { return Type::MEMORY; }
1099   // ClearArray modifies array elements, and so affects only the
1100   // array memory addressed by the bottom_type of its base address.
1101   virtual const class TypePtr *adr_type() const;
1102   virtual Node* Identity(PhaseGVN* phase);
1103   virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
1104   virtual uint match_edge(uint idx) const;
1105   bool is_large() const { return _is_large; }
1106 
1107   // Clear the given area of an object or array.
1108   // The start offset must always be aligned mod BytesPerInt.
1109   // The end offset must always be aligned mod BytesPerLong.
1110   // Return the new memory.
1111   static Node* clear_memory(Node* control, Node* mem, Node* dest,
1112                             intptr_t start_offset,
1113                             intptr_t end_offset,
1114                             PhaseGVN* phase);
1115   static Node* clear_memory(Node* control, Node* mem, Node* dest,
1116                             intptr_t start_offset,
1117                             Node* end_offset,
1118                             PhaseGVN* phase);
1119   static Node* clear_memory(Node* control, Node* mem, Node* dest,
1120                             Node* start_offset,
1121                             Node* end_offset,
1122                             PhaseGVN* phase);
1123   // Return allocation input memory edge if it is different instance
1124   // or itself if it is the one we are looking for.
1125   static bool step_through(Node** np, uint instance_id, PhaseTransform* phase);
1126 };
1127 
1128 //------------------------------MemBar-----------------------------------------
1129 // There are different flavors of Memory Barriers to match the Java Memory
1130 // Model.  Monitor-enter and volatile-load act as Aquires: no following ref
1131 // can be moved to before them.  We insert a MemBar-Acquire after a FastLock or
1132 // volatile-load.  Monitor-exit and volatile-store act as Release: no
1133 // preceding ref can be moved to after them.  We insert a MemBar-Release
1134 // before a FastUnlock or volatile-store.  All volatiles need to be
1135 // serialized, so we follow all volatile-stores with a MemBar-Volatile to
1136 // separate it from any following volatile-load.
1137 class MemBarNode: public MultiNode {
1138   virtual uint hash() const ;                  // { return NO_HASH; }
1139   virtual uint cmp( const Node &n ) const ;    // Always fail, except on self
1140 
1141   virtual uint size_of() const { return sizeof(*this); }
1142   // Memory type this node is serializing.  Usually either rawptr or bottom.
1143   const TypePtr* _adr_type;
1144 
1145 public:
1146   enum {
1147     Precedent = TypeFunc::Parms  // optional edge to force precedence
1148   };
1149   MemBarNode(Compile* C, int alias_idx, Node* precedent);
1150   virtual int Opcode() const = 0;
1151   virtual const class TypePtr *adr_type() const { return _adr_type; }
1152   virtual const Type* Value(PhaseGVN* phase) const;
1153   virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
1154   virtual uint match_edge(uint idx) const { return 0; }
1155   virtual const Type *bottom_type() const { return TypeTuple::MEMBAR; }
1156   virtual Node *match( const ProjNode *proj, const Matcher *m );
1157   // Factory method.  Builds a wide or narrow membar.
1158   // Optional 'precedent' becomes an extra edge if not null.
1159   static MemBarNode* make(Compile* C, int opcode,
1160                           int alias_idx = Compile::AliasIdxBot,
1161                           Node* precedent = NULL);
1162 };
1163 
1164 // "Acquire" - no following ref can move before (but earlier refs can
1165 // follow, like an early Load stalled in cache).  Requires multi-cpu
1166 // visibility.  Inserted after a volatile load.
1167 class MemBarAcquireNode: public MemBarNode {
1168 public:
1169   MemBarAcquireNode(Compile* C, int alias_idx, Node* precedent)
1170     : MemBarNode(C, alias_idx, precedent) {}
1171   virtual int Opcode() const;
1172 };
1173 
1174 // "Acquire" - no following ref can move before (but earlier refs can
1175 // follow, like an early Load stalled in cache).  Requires multi-cpu
1176 // visibility.  Inserted independ of any load, as required
1177 // for intrinsic Unsafe.loadFence().
1178 class LoadFenceNode: public MemBarNode {
1179 public:
1180   LoadFenceNode(Compile* C, int alias_idx, Node* precedent)
1181     : MemBarNode(C, alias_idx, precedent) {}
1182   virtual int Opcode() const;
1183 };
1184 
1185 // "Release" - no earlier ref can move after (but later refs can move
1186 // up, like a speculative pipelined cache-hitting Load).  Requires
1187 // multi-cpu visibility.  Inserted before a volatile store.
1188 class MemBarReleaseNode: public MemBarNode {
1189 public:
1190   MemBarReleaseNode(Compile* C, int alias_idx, Node* precedent)
1191     : MemBarNode(C, alias_idx, precedent) {}
1192   virtual int Opcode() const;
1193 };
1194 
1195 // "Release" - no earlier ref can move after (but later refs can move
1196 // up, like a speculative pipelined cache-hitting Load).  Requires
1197 // multi-cpu visibility.  Inserted independent of any store, as required
1198 // for intrinsic Unsafe.storeFence().
1199 class StoreFenceNode: public MemBarNode {
1200 public:
1201   StoreFenceNode(Compile* C, int alias_idx, Node* precedent)
1202     : MemBarNode(C, alias_idx, precedent) {}
1203   virtual int Opcode() const;
1204 };
1205 
1206 // "Acquire" - no following ref can move before (but earlier refs can
1207 // follow, like an early Load stalled in cache).  Requires multi-cpu
1208 // visibility.  Inserted after a FastLock.
1209 class MemBarAcquireLockNode: public MemBarNode {
1210 public:
1211   MemBarAcquireLockNode(Compile* C, int alias_idx, Node* precedent)
1212     : MemBarNode(C, alias_idx, precedent) {}
1213   virtual int Opcode() const;
1214 };
1215 
1216 // "Release" - no earlier ref can move after (but later refs can move
1217 // up, like a speculative pipelined cache-hitting Load).  Requires
1218 // multi-cpu visibility.  Inserted before a FastUnLock.
1219 class MemBarReleaseLockNode: public MemBarNode {
1220 public:
1221   MemBarReleaseLockNode(Compile* C, int alias_idx, Node* precedent)
1222     : MemBarNode(C, alias_idx, precedent) {}
1223   virtual int Opcode() const;
1224 };
1225 
1226 class MemBarStoreStoreNode: public MemBarNode {
1227 public:
1228   MemBarStoreStoreNode(Compile* C, int alias_idx, Node* precedent)
1229     : MemBarNode(C, alias_idx, precedent) {
1230     init_class_id(Class_MemBarStoreStore);
1231   }
1232   virtual int Opcode() const;
1233 };
1234 
1235 // Ordering between a volatile store and a following volatile load.
1236 // Requires multi-CPU visibility?
1237 class MemBarVolatileNode: public MemBarNode {
1238 public:
1239   MemBarVolatileNode(Compile* C, int alias_idx, Node* precedent)
1240     : MemBarNode(C, alias_idx, precedent) {}
1241   virtual int Opcode() const;
1242 };
1243 
1244 // Ordering within the same CPU.  Used to order unsafe memory references
1245 // inside the compiler when we lack alias info.  Not needed "outside" the
1246 // compiler because the CPU does all the ordering for us.
1247 class MemBarCPUOrderNode: public MemBarNode {
1248 public:
1249   MemBarCPUOrderNode(Compile* C, int alias_idx, Node* precedent)
1250     : MemBarNode(C, alias_idx, precedent) {}
1251   virtual int Opcode() const;
1252   virtual uint ideal_reg() const { return 0; } // not matched in the AD file
1253 };
1254 
1255 class OnSpinWaitNode: public MemBarNode {
1256 public:
1257   OnSpinWaitNode(Compile* C, int alias_idx, Node* precedent)
1258     : MemBarNode(C, alias_idx, precedent) {}
1259   virtual int Opcode() const;
1260 };
1261 
1262 // Isolation of object setup after an AllocateNode and before next safepoint.
1263 // (See comment in memnode.cpp near InitializeNode::InitializeNode for semantics.)
1264 class InitializeNode: public MemBarNode {
1265   friend class AllocateNode;
1266 
1267   enum {
1268     Incomplete    = 0,
1269     Complete      = 1,
1270     WithArraycopy = 2
1271   };
1272   int _is_complete;
1273 
1274   bool _does_not_escape;
1275 
1276 public:
1277   enum {
1278     Control    = TypeFunc::Control,
1279     Memory     = TypeFunc::Memory,     // MergeMem for states affected by this op
1280     RawAddress = TypeFunc::Parms+0,    // the newly-allocated raw address
1281     RawStores  = TypeFunc::Parms+1     // zero or more stores (or TOP)
1282   };
1283 
1284   InitializeNode(Compile* C, int adr_type, Node* rawoop);
1285   virtual int Opcode() const;
1286   virtual uint size_of() const { return sizeof(*this); }
1287   virtual uint ideal_reg() const { return 0; } // not matched in the AD file
1288   virtual const RegMask &in_RegMask(uint) const;  // mask for RawAddress
1289 
1290   // Manage incoming memory edges via a MergeMem on in(Memory):
1291   Node* memory(uint alias_idx);
1292 
1293   // The raw memory edge coming directly from the Allocation.
1294   // The contents of this memory are *always* all-zero-bits.
1295   Node* zero_memory() { return memory(Compile::AliasIdxRaw); }
1296 
1297   // Return the corresponding allocation for this initialization (or null if none).
1298   // (Note: Both InitializeNode::allocation and AllocateNode::initialization
1299   // are defined in graphKit.cpp, which sets up the bidirectional relation.)
1300   AllocateNode* allocation();
1301 
1302   // Anything other than zeroing in this init?
1303   bool is_non_zero();
1304 
1305   // An InitializeNode must completed before macro expansion is done.
1306   // Completion requires that the AllocateNode must be followed by
1307   // initialization of the new memory to zero, then to any initializers.
1308   bool is_complete() { return _is_complete != Incomplete; }
1309   bool is_complete_with_arraycopy() { return (_is_complete & WithArraycopy) != 0; }
1310 
1311   // Mark complete.  (Must not yet be complete.)
1312   void set_complete(PhaseGVN* phase);
1313   void set_complete_with_arraycopy() { _is_complete = Complete | WithArraycopy; }
1314 
1315   bool does_not_escape() { return _does_not_escape; }
1316   void set_does_not_escape() { _does_not_escape = true; }
1317 
1318 #ifdef ASSERT
1319   // ensure all non-degenerate stores are ordered and non-overlapping
1320   bool stores_are_sane(PhaseTransform* phase);
1321 #endif //ASSERT
1322 
1323   // See if this store can be captured; return offset where it initializes.
1324   // Return 0 if the store cannot be moved (any sort of problem).
1325   intptr_t can_capture_store(StoreNode* st, PhaseTransform* phase, bool can_reshape);
1326 
1327   // Capture another store; reformat it to write my internal raw memory.
1328   // Return the captured copy, else NULL if there is some sort of problem.
1329   Node* capture_store(StoreNode* st, intptr_t start, PhaseTransform* phase, bool can_reshape);
1330 
1331   // Find captured store which corresponds to the range [start..start+size).
1332   // Return my own memory projection (meaning the initial zero bits)
1333   // if there is no such store.  Return NULL if there is a problem.
1334   Node* find_captured_store(intptr_t start, int size_in_bytes, PhaseTransform* phase);
1335 
1336   // Called when the associated AllocateNode is expanded into CFG.
1337   Node* complete_stores(Node* rawctl, Node* rawmem, Node* rawptr,
1338                         intptr_t header_size, Node* size_in_bytes,
1339                         PhaseGVN* phase);
1340 
1341  private:
1342   void remove_extra_zeroes();
1343 
1344   // Find out where a captured store should be placed (or already is placed).
1345   int captured_store_insertion_point(intptr_t start, int size_in_bytes,
1346                                      PhaseTransform* phase);
1347 
1348   static intptr_t get_store_offset(Node* st, PhaseTransform* phase);
1349 
1350   Node* make_raw_address(intptr_t offset, PhaseTransform* phase);
1351 
1352   bool detect_init_independence(Node* n, int& count);
1353 
1354   void coalesce_subword_stores(intptr_t header_size, Node* size_in_bytes,
1355                                PhaseGVN* phase);
1356 
1357   intptr_t find_next_fullword_store(uint i, PhaseGVN* phase);
1358 };
1359 
1360 //------------------------------MergeMem---------------------------------------
1361 // (See comment in memnode.cpp near MergeMemNode::MergeMemNode for semantics.)
1362 class MergeMemNode: public Node {
1363   virtual uint hash() const ;                  // { return NO_HASH; }
1364   virtual uint cmp( const Node &n ) const ;    // Always fail, except on self
1365   friend class MergeMemStream;
1366   MergeMemNode(Node* def);  // clients use MergeMemNode::make
1367 
1368 public:
1369   // If the input is a whole memory state, clone it with all its slices intact.
1370   // Otherwise, make a new memory state with just that base memory input.
1371   // In either case, the result is a newly created MergeMem.
1372   static MergeMemNode* make(Node* base_memory);
1373 
1374   virtual int Opcode() const;
1375   virtual Node* Identity(PhaseGVN* phase);
1376   virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
1377   virtual uint ideal_reg() const { return NotAMachineReg; }
1378   virtual uint match_edge(uint idx) const { return 0; }
1379   virtual const RegMask &out_RegMask() const;
1380   virtual const Type *bottom_type() const { return Type::MEMORY; }
1381   virtual const TypePtr *adr_type() const { return TypePtr::BOTTOM; }
1382   // sparse accessors
1383   // Fetch the previously stored "set_memory_at", or else the base memory.
1384   // (Caller should clone it if it is a phi-nest.)
1385   Node* memory_at(uint alias_idx) const;
1386   // set the memory, regardless of its previous value
1387   void set_memory_at(uint alias_idx, Node* n);
1388   // the "base" is the memory that provides the non-finite support
1389   Node* base_memory() const       { return in(Compile::AliasIdxBot); }
1390   // warning: setting the base can implicitly set any of the other slices too
1391   void set_base_memory(Node* def);
1392   // sentinel value which denotes a copy of the base memory:
1393   Node*   empty_memory() const    { return in(Compile::AliasIdxTop); }
1394   static Node* make_empty_memory(); // where the sentinel comes from
1395   bool is_empty_memory(Node* n) const { assert((n == empty_memory()) == n->is_top(), "sanity"); return n->is_top(); }
1396   // hook for the iterator, to perform any necessary setup
1397   void iteration_setup(const MergeMemNode* other = NULL);
1398   // push sentinels until I am at least as long as the other (semantic no-op)
1399   void grow_to_match(const MergeMemNode* other);
1400   bool verify_sparse() const PRODUCT_RETURN0;
1401 #ifndef PRODUCT
1402   virtual void dump_spec(outputStream *st) const;
1403 #endif
1404 };
1405 
1406 class MergeMemStream : public StackObj {
1407  private:
1408   MergeMemNode*       _mm;
1409   const MergeMemNode* _mm2;  // optional second guy, contributes non-empty iterations
1410   Node*               _mm_base;  // loop-invariant base memory of _mm
1411   int                 _idx;
1412   int                 _cnt;
1413   Node*               _mem;
1414   Node*               _mem2;
1415   int                 _cnt2;
1416 
1417   void init(MergeMemNode* mm, const MergeMemNode* mm2 = NULL) {
1418     // subsume_node will break sparseness at times, whenever a memory slice
1419     // folds down to a copy of the base ("fat") memory.  In such a case,
1420     // the raw edge will update to base, although it should be top.
1421     // This iterator will recognize either top or base_memory as an
1422     // "empty" slice.  See is_empty, is_empty2, and next below.
1423     //
1424     // The sparseness property is repaired in MergeMemNode::Ideal.
1425     // As long as access to a MergeMem goes through this iterator
1426     // or the memory_at accessor, flaws in the sparseness will
1427     // never be observed.
1428     //
1429     // Also, iteration_setup repairs sparseness.
1430     assert(mm->verify_sparse(), "please, no dups of base");
1431     assert(mm2==NULL || mm2->verify_sparse(), "please, no dups of base");
1432 
1433     _mm  = mm;
1434     _mm_base = mm->base_memory();
1435     _mm2 = mm2;
1436     _cnt = mm->req();
1437     _idx = Compile::AliasIdxBot-1; // start at the base memory
1438     _mem = NULL;
1439     _mem2 = NULL;
1440   }
1441 
1442 #ifdef ASSERT
1443   Node* check_memory() const {
1444     if (at_base_memory())
1445       return _mm->base_memory();
1446     else if ((uint)_idx < _mm->req() && !_mm->in(_idx)->is_top())
1447       return _mm->memory_at(_idx);
1448     else
1449       return _mm_base;
1450   }
1451   Node* check_memory2() const {
1452     return at_base_memory()? _mm2->base_memory(): _mm2->memory_at(_idx);
1453   }
1454 #endif
1455 
1456   static bool match_memory(Node* mem, const MergeMemNode* mm, int idx) PRODUCT_RETURN0;
1457   void assert_synch() const {
1458     assert(!_mem || _idx >= _cnt || match_memory(_mem, _mm, _idx),
1459            "no side-effects except through the stream");
1460   }
1461 
1462  public:
1463 
1464   // expected usages:
1465   // for (MergeMemStream mms(mem->is_MergeMem()); next_non_empty(); ) { ... }
1466   // for (MergeMemStream mms(mem1, mem2); next_non_empty2(); ) { ... }
1467 
1468   // iterate over one merge
1469   MergeMemStream(MergeMemNode* mm) {
1470     mm->iteration_setup();
1471     init(mm);
1472     debug_only(_cnt2 = 999);
1473   }
1474   // iterate in parallel over two merges
1475   // only iterates through non-empty elements of mm2
1476   MergeMemStream(MergeMemNode* mm, const MergeMemNode* mm2) {
1477     assert(mm2, "second argument must be a MergeMem also");
1478     ((MergeMemNode*)mm2)->iteration_setup();  // update hidden state
1479     mm->iteration_setup(mm2);
1480     init(mm, mm2);
1481     _cnt2 = mm2->req();
1482   }
1483 #ifdef ASSERT
1484   ~MergeMemStream() {
1485     assert_synch();
1486   }
1487 #endif
1488 
1489   MergeMemNode* all_memory() const {
1490     return _mm;
1491   }
1492   Node* base_memory() const {
1493     assert(_mm_base == _mm->base_memory(), "no update to base memory, please");
1494     return _mm_base;
1495   }
1496   const MergeMemNode* all_memory2() const {
1497     assert(_mm2 != NULL, "");
1498     return _mm2;
1499   }
1500   bool at_base_memory() const {
1501     return _idx == Compile::AliasIdxBot;
1502   }
1503   int alias_idx() const {
1504     assert(_mem, "must call next 1st");
1505     return _idx;
1506   }
1507 
1508   const TypePtr* adr_type() const {
1509     return Compile::current()->get_adr_type(alias_idx());
1510   }
1511 
1512   const TypePtr* adr_type(Compile* C) const {
1513     return C->get_adr_type(alias_idx());
1514   }
1515   bool is_empty() const {
1516     assert(_mem, "must call next 1st");
1517     assert(_mem->is_top() == (_mem==_mm->empty_memory()), "correct sentinel");
1518     return _mem->is_top();
1519   }
1520   bool is_empty2() const {
1521     assert(_mem2, "must call next 1st");
1522     assert(_mem2->is_top() == (_mem2==_mm2->empty_memory()), "correct sentinel");
1523     return _mem2->is_top();
1524   }
1525   Node* memory() const {
1526     assert(!is_empty(), "must not be empty");
1527     assert_synch();
1528     return _mem;
1529   }
1530   // get the current memory, regardless of empty or non-empty status
1531   Node* force_memory() const {
1532     assert(!is_empty() || !at_base_memory(), "");
1533     // Use _mm_base to defend against updates to _mem->base_memory().
1534     Node *mem = _mem->is_top() ? _mm_base : _mem;
1535     assert(mem == check_memory(), "");
1536     return mem;
1537   }
1538   Node* memory2() const {
1539     assert(_mem2 == check_memory2(), "");
1540     return _mem2;
1541   }
1542   void set_memory(Node* mem) {
1543     if (at_base_memory()) {
1544       // Note that this does not change the invariant _mm_base.
1545       _mm->set_base_memory(mem);
1546     } else {
1547       _mm->set_memory_at(_idx, mem);
1548     }
1549     _mem = mem;
1550     assert_synch();
1551   }
1552 
1553   // Recover from a side effect to the MergeMemNode.
1554   void set_memory() {
1555     _mem = _mm->in(_idx);
1556   }
1557 
1558   bool next()  { return next(false); }
1559   bool next2() { return next(true); }
1560 
1561   bool next_non_empty()  { return next_non_empty(false); }
1562   bool next_non_empty2() { return next_non_empty(true); }
1563   // next_non_empty2 can yield states where is_empty() is true
1564 
1565  private:
1566   // find the next item, which might be empty
1567   bool next(bool have_mm2) {
1568     assert((_mm2 != NULL) == have_mm2, "use other next");
1569     assert_synch();
1570     if (++_idx < _cnt) {
1571       // Note:  This iterator allows _mm to be non-sparse.
1572       // It behaves the same whether _mem is top or base_memory.
1573       _mem = _mm->in(_idx);
1574       if (have_mm2)
1575         _mem2 = _mm2->in((_idx < _cnt2) ? _idx : Compile::AliasIdxTop);
1576       return true;
1577     }
1578     return false;
1579   }
1580 
1581   // find the next non-empty item
1582   bool next_non_empty(bool have_mm2) {
1583     while (next(have_mm2)) {
1584       if (!is_empty()) {
1585         // make sure _mem2 is filled in sensibly
1586         if (have_mm2 && _mem2->is_top())  _mem2 = _mm2->base_memory();
1587         return true;
1588       } else if (have_mm2 && !is_empty2()) {
1589         return true;   // is_empty() == true
1590       }
1591     }
1592     return false;
1593   }
1594 };
1595 
1596 //------------------------------Prefetch---------------------------------------
1597 
1598 // Allocation prefetch which may fault, TLAB size have to be adjusted.
1599 class PrefetchAllocationNode : public Node {
1600 public:
1601   PrefetchAllocationNode(Node *mem, Node *adr) : Node(0,mem,adr) {}
1602   virtual int Opcode() const;
1603   virtual uint ideal_reg() const { return NotAMachineReg; }
1604   virtual uint match_edge(uint idx) const { return idx==2; }
1605   virtual const Type *bottom_type() const { return ( AllocatePrefetchStyle == 3 ) ? Type::MEMORY : Type::ABIO; }
1606 };
1607 
1608 #endif // SHARE_VM_OPTO_MEMNODE_HPP