1 /*
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   3  * Copyright (c) 2024, Alibaba Group Holding Limited. All rights reserved.
   4  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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   7  * under the terms of the GNU General Public License version 2 only, as
   8  * published by the Free Software Foundation.
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  10  * This code is distributed in the hope that it will be useful, but WITHOUT
  11  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  12  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  13  * version 2 for more details (a copy is included in the LICENSE file that
  14  * accompanied this code).
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  18  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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  25 
  26 #ifndef SHARE_OPTO_MEMNODE_HPP
  27 #define SHARE_OPTO_MEMNODE_HPP
  28 
  29 #include "opto/multnode.hpp"
  30 #include "opto/node.hpp"
  31 #include "opto/opcodes.hpp"
  32 #include "opto/type.hpp"
  33 
  34 // Portions of code courtesy of Clifford Click
  35 
  36 class MultiNode;
  37 class PhaseCCP;
  38 class PhaseTransform;
  39 
  40 //------------------------------MemNode----------------------------------------
  41 // Load or Store, possibly throwing a null pointer exception
  42 class MemNode : public Node {
  43 private:
  44   bool _unaligned_access; // Unaligned access from unsafe
  45   bool _mismatched_access; // Mismatched access from unsafe: byte read in integer array for instance
  46   bool _unsafe_access;     // Access of unsafe origin.
  47   uint8_t _barrier_data;   // Bit field with barrier information
  48 
  49 protected:
  50 #ifdef ASSERT
  51   const TypePtr* _adr_type;     // What kind of memory is being addressed?
  52 #endif
  53   virtual uint size_of() const;
  54 public:
  55   enum { Control,               // When is it safe to do this load?
  56          Memory,                // Chunk of memory is being loaded from
  57          Address,               // Actually address, derived from base
  58          ValueIn                // Value to store
  59   };
  60   typedef enum { unordered = 0,
  61                  acquire,       // Load has to acquire or be succeeded by MemBarAcquire.
  62                  release,       // Store has to release or be preceded by MemBarRelease.
  63                  seqcst,        // LoadStore has to have both acquire and release semantics.
  64                  unset          // The memory ordering is not set (used for testing)
  65   } MemOrd;
  66 protected:
  67   MemNode( Node *c0, Node *c1, Node *c2, const TypePtr* at ) :
  68       Node(c0,c1,c2),
  69       _unaligned_access(false),
  70       _mismatched_access(false),
  71       _unsafe_access(false),
  72       _barrier_data(0) {
  73     init_class_id(Class_Mem);
  74     DEBUG_ONLY(_adr_type=at; adr_type();)
  75   }
  76   MemNode( Node *c0, Node *c1, Node *c2, const TypePtr* at, Node *c3 ) :
  77       Node(c0,c1,c2,c3),
  78       _unaligned_access(false),
  79       _mismatched_access(false),
  80       _unsafe_access(false),
  81       _barrier_data(0) {
  82     init_class_id(Class_Mem);
  83     DEBUG_ONLY(_adr_type=at; adr_type();)
  84   }
  85   MemNode( Node *c0, Node *c1, Node *c2, const TypePtr* at, Node *c3, Node *c4) :
  86       Node(c0,c1,c2,c3,c4),
  87       _unaligned_access(false),
  88       _mismatched_access(false),
  89       _unsafe_access(false),
  90       _barrier_data(0) {
  91     init_class_id(Class_Mem);
  92     DEBUG_ONLY(_adr_type=at; adr_type();)
  93   }
  94 
  95   virtual Node* find_previous_arraycopy(PhaseValues* phase, Node* ld_alloc, Node*& mem, bool can_see_stored_value) const { return nullptr; }
  96   ArrayCopyNode* find_array_copy_clone(Node* ld_alloc, Node* mem) const;
  97   static bool check_if_adr_maybe_raw(Node* adr);
  98 
  99 public:
 100   // Helpers for the optimizer.  Documented in memnode.cpp.
 101   static bool detect_ptr_independence(Node* p1, AllocateNode* a1,
 102                                       Node* p2, AllocateNode* a2,
 103                                       PhaseTransform* phase);
 104   static bool adr_phi_is_loop_invariant(Node* adr_phi, Node* cast);
 105 
 106   static Node *optimize_simple_memory_chain(Node *mchain, const TypeOopPtr *t_oop, Node *load, PhaseGVN *phase);
 107   static Node *optimize_memory_chain(Node *mchain, const TypePtr *t_adr, Node *load, PhaseGVN *phase);
 108   // The following two should probably be phase-specific functions:
 109   static DomResult maybe_all_controls_dominate(Node* dom, Node* sub);
 110   static bool all_controls_dominate(Node* dom, Node* sub) {
 111     DomResult dom_result = maybe_all_controls_dominate(dom, sub);
 112     return dom_result == DomResult::Dominate;
 113   }
 114 
 115   virtual const class TypePtr *adr_type() const;  // returns bottom_type of address
 116 
 117   // Shared code for Ideal methods:
 118   Node *Ideal_common(PhaseGVN *phase, bool can_reshape);  // Return -1 for short-circuit null.
 119 
 120   // Helper function for adr_type() implementations.
 121   static const TypePtr* calculate_adr_type(const Type* t, const TypePtr* cross_check = nullptr);
 122 
 123   // Raw access function, to allow copying of adr_type efficiently in
 124   // product builds and retain the debug info for debug builds.
 125   const TypePtr *raw_adr_type() const {
 126     return DEBUG_ONLY(_adr_type) NOT_DEBUG(nullptr);
 127   }
 128 
 129 #ifdef ASSERT
 130   void set_adr_type(const TypePtr* adr_type) { _adr_type = adr_type; }
 131 #endif
 132 
 133   // Return the barrier data of n, if available, or 0 otherwise.
 134   static uint8_t barrier_data(const Node* n);
 135 
 136   // Map a load or store opcode to its corresponding store opcode.
 137   // (Return -1 if unknown.)
 138   virtual int store_Opcode() const { return -1; }
 139 
 140   // What is the type of the value in memory?  (T_VOID mean "unspecified".)
 141   // The returned type is a property of the value that is loaded/stored and
 142   // not the memory that is accessed. For mismatched memory accesses
 143   // they might differ. For instance, a value of type 'short' may be stored
 144   // into an array of elements of type 'long'.
 145   virtual BasicType value_basic_type() const = 0;
 146   virtual int memory_size() const {
 147 #ifdef ASSERT
 148     return type2aelembytes(value_basic_type(), true);
 149 #else
 150     return type2aelembytes(value_basic_type());
 151 #endif
 152   }
 153 
 154   uint8_t barrier_data() { return _barrier_data; }
 155   void set_barrier_data(uint8_t barrier_data) { _barrier_data = barrier_data; }
 156 
 157   // Search through memory states which precede this node (load or store).
 158   // Look for an exact match for the address, with no intervening
 159   // aliased stores.
 160   Node* find_previous_store(PhaseValues* phase);
 161 
 162   // Can this node (load or store) accurately see a stored value in
 163   // the given memory state?  (The state may or may not be in(Memory).)
 164   Node* can_see_stored_value(Node* st, PhaseValues* phase) const;
 165 
 166   void set_unaligned_access() { _unaligned_access = true; }
 167   bool is_unaligned_access() const { return _unaligned_access; }
 168   void set_mismatched_access() { _mismatched_access = true; }
 169   bool is_mismatched_access() const { return _mismatched_access; }
 170   void set_unsafe_access() { _unsafe_access = true; }
 171   bool is_unsafe_access() const { return _unsafe_access; }
 172 
 173 #ifndef PRODUCT
 174   static void dump_adr_type(const Node* mem, const TypePtr* adr_type, outputStream *st);
 175   virtual void dump_spec(outputStream *st) const;
 176 #endif
 177 };
 178 
 179 //------------------------------LoadNode---------------------------------------
 180 // Load value; requires Memory and Address
 181 class LoadNode : public MemNode {
 182 public:
 183   // Some loads (from unsafe) should be pinned: they don't depend only
 184   // on the dominating test.  The field _control_dependency below records
 185   // whether that node depends only on the dominating test.
 186   // Pinned and UnknownControl are similar, but differ in that Pinned
 187   // loads are not allowed to float across safepoints, whereas UnknownControl
 188   // loads are allowed to do that. Therefore, Pinned is stricter.
 189   enum ControlDependency {
 190     Pinned,
 191     UnknownControl,
 192     DependsOnlyOnTest
 193   };
 194 
 195 private:
 196   // LoadNode::hash() doesn't take the _control_dependency field
 197   // into account: If the graph already has a non-pinned LoadNode and
 198   // we add a pinned LoadNode with the same inputs, it's safe for GVN
 199   // to replace the pinned LoadNode with the non-pinned LoadNode,
 200   // otherwise it wouldn't be safe to have a non pinned LoadNode with
 201   // those inputs in the first place. If the graph already has a
 202   // pinned LoadNode and we add a non pinned LoadNode with the same
 203   // inputs, it's safe (but suboptimal) for GVN to replace the
 204   // non-pinned LoadNode by the pinned LoadNode.
 205   ControlDependency _control_dependency;
 206 
 207   // On platforms with weak memory ordering (e.g., PPC) we distinguish
 208   // loads that can be reordered, and such requiring acquire semantics to
 209   // adhere to the Java specification.  The required behaviour is stored in
 210   // this field.
 211   const MemOrd _mo;
 212 
 213   AllocateNode* is_new_object_mark_load() const;
 214 
 215 protected:
 216   virtual bool cmp(const Node &n) const;
 217   virtual uint size_of() const; // Size is bigger
 218   // Should LoadNode::Ideal() attempt to remove control edges?
 219   virtual bool can_remove_control() const;
 220   const Type* const _type;      // What kind of value is loaded?
 221 
 222   virtual Node* find_previous_arraycopy(PhaseValues* phase, Node* ld_alloc, Node*& mem, bool can_see_stored_value) const;
 223 public:
 224 
 225   LoadNode(Node *c, Node *mem, Node *adr, const TypePtr* at, const Type *rt, MemOrd mo, ControlDependency control_dependency)
 226     : MemNode(c,mem,adr,at), _control_dependency(control_dependency), _mo(mo), _type(rt) {
 227     init_class_id(Class_Load);
 228   }
 229   inline bool is_unordered() const { return !is_acquire(); }
 230   inline bool is_acquire() const {
 231     assert(_mo == unordered || _mo == acquire, "unexpected");
 232     return _mo == acquire;
 233   }
 234   inline bool is_unsigned() const {
 235     int lop = Opcode();
 236     return (lop == Op_LoadUB) || (lop == Op_LoadUS);
 237   }
 238 
 239   // Polymorphic factory method:
 240   static Node* make(PhaseGVN& gvn, Node* c, Node* mem, Node* adr,
 241                     const TypePtr* at, const Type* rt, BasicType bt,
 242                     MemOrd mo, ControlDependency control_dependency = DependsOnlyOnTest,
 243                     bool require_atomic_access = false, bool unaligned = false, bool mismatched = false, bool unsafe = false,
 244                     uint8_t barrier_data = 0);
 245 
 246   virtual uint hash()   const;  // Check the type
 247 
 248   // Handle algebraic identities here.  If we have an identity, return the Node
 249   // we are equivalent to.  We look for Load of a Store.
 250   virtual Node* Identity(PhaseGVN* phase);
 251 
 252   // If the load is from Field memory and the pointer is non-null, it might be possible to
 253   // zero out the control input.
 254   // If the offset is constant and the base is an object allocation,
 255   // try to hook me up to the exact initializing store.
 256   virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
 257 
 258   // Return true if it's possible to split the Load through a Phi merging the bases
 259   bool can_split_through_phi_base(PhaseGVN *phase);
 260 
 261   // Split instance field load through Phi.
 262   Node* split_through_phi(PhaseGVN *phase, bool ignore_missing_instance_id = false);
 263 
 264   // Recover original value from boxed values
 265   Node *eliminate_autobox(PhaseIterGVN *igvn);
 266 
 267   // Compute a new Type for this node.  Basically we just do the pre-check,
 268   // then call the virtual add() to set the type.
 269   virtual const Type* Value(PhaseGVN* phase) const;
 270 
 271   // Common methods for LoadKlass and LoadNKlass nodes.
 272   const Type* klass_value_common(PhaseGVN* phase) const;
 273   Node* klass_identity_common(PhaseGVN* phase);
 274 
 275   virtual uint ideal_reg() const;
 276   virtual const Type *bottom_type() const;
 277   // Following method is copied from TypeNode:
 278   void set_type(const Type* t) {
 279     assert(t != nullptr, "sanity");
 280     DEBUG_ONLY(uint check_hash = (VerifyHashTableKeys && _hash_lock) ? hash() : NO_HASH);
 281     *(const Type**)&_type = t;   // cast away const-ness
 282     // If this node is in the hash table, make sure it doesn't need a rehash.
 283     assert(check_hash == NO_HASH || check_hash == hash(), "type change must preserve hash code");
 284   }
 285   const Type* type() const { assert(_type != nullptr, "sanity"); return _type; };
 286 
 287   // Do not match memory edge
 288   virtual uint match_edge(uint idx) const;
 289 
 290   // Map a load opcode to its corresponding store opcode.
 291   virtual int store_Opcode() const = 0;
 292 
 293   // Check if the load's memory input is a Phi node with the same control.
 294   bool is_instance_field_load_with_local_phi(Node* ctrl);
 295 
 296   Node* convert_to_unsigned_load(PhaseGVN& gvn);
 297   Node* convert_to_signed_load(PhaseGVN& gvn);
 298 
 299   bool  has_reinterpret_variant(const Type* rt);
 300   Node* convert_to_reinterpret_load(PhaseGVN& gvn, const Type* rt);
 301 
 302   ControlDependency control_dependency() const { return _control_dependency; }
 303   bool has_unknown_control_dependency() const  { return _control_dependency == UnknownControl; }
 304   bool has_pinned_control_dependency() const   { return _control_dependency == Pinned; }
 305 
 306   LoadNode* pin_array_access_node() const;
 307 
 308 #ifndef PRODUCT
 309   virtual void dump_spec(outputStream *st) const;
 310 #endif
 311 #ifdef ASSERT
 312   // Helper function to allow a raw load without control edge for some cases
 313   static bool is_immutable_value(Node* adr);
 314 #endif
 315 protected:
 316   const Type* load_array_final_field(const TypeKlassPtr *tkls,
 317                                      ciKlass* klass) const;
 318 
 319   Node* can_see_arraycopy_value(Node* st, PhaseGVN* phase) const;
 320 
 321   // depends_only_on_test is almost always true, and needs to be almost always
 322   // true to enable key hoisting & commoning optimizations.  However, for the
 323   // special case of RawPtr loads from TLS top & end, and other loads performed by
 324   // GC barriers, the control edge carries the dependence preventing hoisting past
 325   // a Safepoint instead of the memory edge.  (An unfortunate consequence of having
 326   // Safepoints not set Raw Memory; itself an unfortunate consequence of having Nodes
 327   // which produce results (new raw memory state) inside of loops preventing all
 328   // manner of other optimizations).  Basically, it's ugly but so is the alternative.
 329   // See comment in macro.cpp, around line 125 expand_allocate_common().
 330   virtual bool depends_only_on_test() const {
 331     return adr_type() != TypeRawPtr::BOTTOM && _control_dependency == DependsOnlyOnTest;
 332   }
 333 
 334   LoadNode* clone_pinned() const;
 335 };
 336 
 337 //------------------------------LoadBNode--------------------------------------
 338 // Load a byte (8bits signed) from memory
 339 class LoadBNode : public LoadNode {
 340 public:
 341   LoadBNode(Node *c, Node *mem, Node *adr, const TypePtr* at, const TypeInt *ti, MemOrd mo, ControlDependency control_dependency = DependsOnlyOnTest)
 342     : LoadNode(c, mem, adr, at, ti, mo, control_dependency) {}
 343   virtual int Opcode() const;
 344   virtual uint ideal_reg() const { return Op_RegI; }
 345   virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
 346   virtual const Type* Value(PhaseGVN* phase) const;
 347   virtual int store_Opcode() const { return Op_StoreB; }
 348   virtual BasicType value_basic_type() const { return T_BYTE; }
 349 };
 350 
 351 //------------------------------LoadUBNode-------------------------------------
 352 // Load a unsigned byte (8bits unsigned) from memory
 353 class LoadUBNode : public LoadNode {
 354 public:
 355   LoadUBNode(Node* c, Node* mem, Node* adr, const TypePtr* at, const TypeInt* ti, MemOrd mo, ControlDependency control_dependency = DependsOnlyOnTest)
 356     : LoadNode(c, mem, adr, at, ti, mo, control_dependency) {}
 357   virtual int Opcode() const;
 358   virtual uint ideal_reg() const { return Op_RegI; }
 359   virtual Node* Ideal(PhaseGVN *phase, bool can_reshape);
 360   virtual const Type* Value(PhaseGVN* phase) const;
 361   virtual int store_Opcode() const { return Op_StoreB; }
 362   virtual BasicType value_basic_type() const { return T_BYTE; }
 363 };
 364 
 365 //------------------------------LoadUSNode-------------------------------------
 366 // Load an unsigned short/char (16bits unsigned) from memory
 367 class LoadUSNode : public LoadNode {
 368 public:
 369   LoadUSNode(Node *c, Node *mem, Node *adr, const TypePtr* at, const TypeInt *ti, MemOrd mo, ControlDependency control_dependency = DependsOnlyOnTest)
 370     : LoadNode(c, mem, adr, at, ti, mo, control_dependency) {}
 371   virtual int Opcode() const;
 372   virtual uint ideal_reg() const { return Op_RegI; }
 373   virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
 374   virtual const Type* Value(PhaseGVN* phase) const;
 375   virtual int store_Opcode() const { return Op_StoreC; }
 376   virtual BasicType value_basic_type() const { return T_CHAR; }
 377 };
 378 
 379 //------------------------------LoadSNode--------------------------------------
 380 // Load a short (16bits signed) from memory
 381 class LoadSNode : public LoadNode {
 382 public:
 383   LoadSNode(Node *c, Node *mem, Node *adr, const TypePtr* at, const TypeInt *ti, MemOrd mo, ControlDependency control_dependency = DependsOnlyOnTest)
 384     : LoadNode(c, mem, adr, at, ti, mo, control_dependency) {}
 385   virtual int Opcode() const;
 386   virtual uint ideal_reg() const { return Op_RegI; }
 387   virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
 388   virtual const Type* Value(PhaseGVN* phase) const;
 389   virtual int store_Opcode() const { return Op_StoreC; }
 390   virtual BasicType value_basic_type() const { return T_SHORT; }
 391 };
 392 
 393 //------------------------------LoadINode--------------------------------------
 394 // Load an integer from memory
 395 class LoadINode : public LoadNode {
 396 public:
 397   LoadINode(Node *c, Node *mem, Node *adr, const TypePtr* at, const TypeInt *ti, MemOrd mo, ControlDependency control_dependency = DependsOnlyOnTest)
 398     : LoadNode(c, mem, adr, at, ti, mo, control_dependency) {}
 399   virtual int Opcode() const;
 400   virtual uint ideal_reg() const { return Op_RegI; }
 401   virtual int store_Opcode() const { return Op_StoreI; }
 402   virtual BasicType value_basic_type() const { return T_INT; }
 403 };
 404 
 405 //------------------------------LoadRangeNode----------------------------------
 406 // Load an array length from the array
 407 class LoadRangeNode : public LoadINode {
 408 public:
 409   LoadRangeNode(Node *c, Node *mem, Node *adr, const TypeInt *ti = TypeInt::POS)
 410     : LoadINode(c, mem, adr, TypeAryPtr::RANGE, ti, MemNode::unordered) {}
 411   virtual int Opcode() const;
 412   virtual const Type* Value(PhaseGVN* phase) const;
 413   virtual Node* Identity(PhaseGVN* phase);
 414   virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
 415 };
 416 
 417 //------------------------------LoadLNode--------------------------------------
 418 // Load a long from memory
 419 class LoadLNode : public LoadNode {
 420   virtual uint hash() const { return LoadNode::hash() + _require_atomic_access; }
 421   virtual bool cmp( const Node &n ) const {
 422     return _require_atomic_access == ((LoadLNode&)n)._require_atomic_access
 423       && LoadNode::cmp(n);
 424   }
 425   virtual uint size_of() const { return sizeof(*this); }
 426   const bool _require_atomic_access;  // is piecewise load forbidden?
 427 
 428 public:
 429   LoadLNode(Node *c, Node *mem, Node *adr, const TypePtr* at, const TypeLong *tl,
 430             MemOrd mo, ControlDependency control_dependency = DependsOnlyOnTest, bool require_atomic_access = false)
 431     : LoadNode(c, mem, adr, at, tl, mo, control_dependency), _require_atomic_access(require_atomic_access) {}
 432   virtual int Opcode() const;
 433   virtual uint ideal_reg() const { return Op_RegL; }
 434   virtual int store_Opcode() const { return Op_StoreL; }
 435   virtual BasicType value_basic_type() const { return T_LONG; }
 436   bool require_atomic_access() const { return _require_atomic_access; }
 437 
 438 #ifndef PRODUCT
 439   virtual void dump_spec(outputStream *st) const {
 440     LoadNode::dump_spec(st);
 441     if (_require_atomic_access)  st->print(" Atomic!");
 442   }
 443 #endif
 444 };
 445 
 446 //------------------------------LoadL_unalignedNode----------------------------
 447 // Load a long from unaligned memory
 448 class LoadL_unalignedNode : public LoadLNode {
 449 public:
 450   LoadL_unalignedNode(Node *c, Node *mem, Node *adr, const TypePtr* at, MemOrd mo, ControlDependency control_dependency = DependsOnlyOnTest)
 451     : LoadLNode(c, mem, adr, at, TypeLong::LONG, mo, control_dependency) {}
 452   virtual int Opcode() const;
 453 };
 454 
 455 //------------------------------LoadFNode--------------------------------------
 456 // Load a float (64 bits) from memory
 457 class LoadFNode : public LoadNode {
 458 public:
 459   LoadFNode(Node *c, Node *mem, Node *adr, const TypePtr* at, const Type *t, MemOrd mo, ControlDependency control_dependency = DependsOnlyOnTest)
 460     : LoadNode(c, mem, adr, at, t, mo, control_dependency) {}
 461   virtual int Opcode() const;
 462   virtual uint ideal_reg() const { return Op_RegF; }
 463   virtual int store_Opcode() const { return Op_StoreF; }
 464   virtual BasicType value_basic_type() const { return T_FLOAT; }
 465 };
 466 
 467 //------------------------------LoadDNode--------------------------------------
 468 // Load a double (64 bits) from memory
 469 class LoadDNode : public LoadNode {
 470   virtual uint hash() const { return LoadNode::hash() + _require_atomic_access; }
 471   virtual bool cmp( const Node &n ) const {
 472     return _require_atomic_access == ((LoadDNode&)n)._require_atomic_access
 473       && LoadNode::cmp(n);
 474   }
 475   virtual uint size_of() const { return sizeof(*this); }
 476   const bool _require_atomic_access;  // is piecewise load forbidden?
 477 
 478 public:
 479   LoadDNode(Node *c, Node *mem, Node *adr, const TypePtr* at, const Type *t,
 480             MemOrd mo, ControlDependency control_dependency = DependsOnlyOnTest, bool require_atomic_access = false)
 481     : LoadNode(c, mem, adr, at, t, mo, control_dependency), _require_atomic_access(require_atomic_access) {}
 482   virtual int Opcode() const;
 483   virtual uint ideal_reg() const { return Op_RegD; }
 484   virtual int store_Opcode() const { return Op_StoreD; }
 485   virtual BasicType value_basic_type() const { return T_DOUBLE; }
 486   bool require_atomic_access() const { return _require_atomic_access; }
 487 
 488 #ifndef PRODUCT
 489   virtual void dump_spec(outputStream *st) const {
 490     LoadNode::dump_spec(st);
 491     if (_require_atomic_access)  st->print(" Atomic!");
 492   }
 493 #endif
 494 };
 495 
 496 //------------------------------LoadD_unalignedNode----------------------------
 497 // Load a double from unaligned memory
 498 class LoadD_unalignedNode : public LoadDNode {
 499 public:
 500   LoadD_unalignedNode(Node *c, Node *mem, Node *adr, const TypePtr* at, MemOrd mo, ControlDependency control_dependency = DependsOnlyOnTest)
 501     : LoadDNode(c, mem, adr, at, Type::DOUBLE, mo, control_dependency) {}
 502   virtual int Opcode() const;
 503 };
 504 
 505 //------------------------------LoadPNode--------------------------------------
 506 // Load a pointer from memory (either object or array)
 507 class LoadPNode : public LoadNode {
 508 public:
 509   LoadPNode(Node *c, Node *mem, Node *adr, const TypePtr *at, const TypePtr* t, MemOrd mo, ControlDependency control_dependency = DependsOnlyOnTest)
 510     : LoadNode(c, mem, adr, at, t, mo, control_dependency) {}
 511   virtual int Opcode() const;
 512   virtual uint ideal_reg() const { return Op_RegP; }
 513   virtual int store_Opcode() const { return Op_StoreP; }
 514   virtual BasicType value_basic_type() const { return T_ADDRESS; }
 515 };
 516 
 517 
 518 //------------------------------LoadNNode--------------------------------------
 519 // Load a narrow oop from memory (either object or array)
 520 class LoadNNode : public LoadNode {
 521 public:
 522   LoadNNode(Node *c, Node *mem, Node *adr, const TypePtr *at, const Type* t, MemOrd mo, ControlDependency control_dependency = DependsOnlyOnTest)
 523     : LoadNode(c, mem, adr, at, t, mo, control_dependency) {}
 524   virtual Node* Ideal(PhaseGVN* phase, bool can_reshape);
 525   virtual int Opcode() const;
 526   virtual uint ideal_reg() const { return Op_RegN; }
 527   virtual int store_Opcode() const { return Op_StoreN; }
 528   virtual BasicType value_basic_type() const { return T_NARROWOOP; }
 529 };
 530 
 531 //------------------------------LoadKlassNode----------------------------------
 532 // Load a Klass from an object
 533 class LoadKlassNode : public LoadPNode {
 534 private:
 535   LoadKlassNode(Node* mem, Node* adr, const TypePtr* at, const TypeKlassPtr* tk, MemOrd mo)
 536     : LoadPNode(nullptr, mem, adr, at, tk, mo) {}
 537 
 538 public:
 539   virtual int Opcode() const;
 540   virtual const Type* Value(PhaseGVN* phase) const;
 541   virtual Node* Identity(PhaseGVN* phase);
 542   virtual bool depends_only_on_test() const { return true; }
 543 
 544   // Polymorphic factory method:
 545   static Node* make(PhaseGVN& gvn, Node* mem, Node* adr, const TypePtr* at,
 546                     const TypeKlassPtr* tk = TypeInstKlassPtr::OBJECT);
 547 };
 548 
 549 //------------------------------LoadNKlassNode---------------------------------
 550 // Load a narrow Klass from an object.
 551 // With compact headers, the input address (adr) does not point at the exact
 552 // header position where the (narrow) class pointer is located, but into the
 553 // middle of the mark word (see oopDesc::klass_offset_in_bytes()). This node
 554 // implicitly shifts the loaded value (markWord::klass_shift_at_offset bits) to
 555 // extract the actual class pointer. C2's type system is agnostic on whether the
 556 // input address directly points into the class pointer.
 557 class LoadNKlassNode : public LoadNNode {
 558 private:
 559   friend Node* LoadKlassNode::make(PhaseGVN&, Node*, Node*, const TypePtr*, const TypeKlassPtr*);
 560   LoadNKlassNode(Node* mem, Node* adr, const TypePtr* at, const TypeNarrowKlass* tk, MemOrd mo)
 561     : LoadNNode(nullptr, mem, adr, at, tk, mo) {}
 562 
 563 public:
 564   virtual int Opcode() const;
 565   virtual uint ideal_reg() const { return Op_RegN; }
 566   virtual int store_Opcode() const { return Op_StoreNKlass; }
 567   virtual BasicType value_basic_type() const { return T_NARROWKLASS; }
 568 
 569   virtual const Type* Value(PhaseGVN* phase) const;
 570   virtual Node* Identity(PhaseGVN* phase);
 571   virtual bool depends_only_on_test() const { return true; }
 572 };
 573 
 574 //------------------------------StoreNode--------------------------------------
 575 // Store value; requires Store, Address and Value
 576 class StoreNode : public MemNode {
 577 private:
 578   // On platforms with weak memory ordering (e.g., PPC) we distinguish
 579   // stores that can be reordered, and such requiring release semantics to
 580   // adhere to the Java specification.  The required behaviour is stored in
 581   // this field.
 582   const MemOrd _mo;
 583   // Needed for proper cloning.
 584   virtual uint size_of() const { return sizeof(*this); }
 585 protected:
 586   virtual bool cmp( const Node &n ) const;
 587   virtual bool depends_only_on_test() const { return false; }
 588 
 589   Node *Ideal_masked_input       (PhaseGVN *phase, uint mask);
 590   Node* Ideal_sign_extended_input(PhaseGVN* phase, int num_rejected_bits);
 591 
 592 public:
 593   // We must ensure that stores of object references will be visible
 594   // only after the object's initialization. So the callers of this
 595   // procedure must indicate that the store requires `release'
 596   // semantics, if the stored value is an object reference that might
 597   // point to a new object and may become externally visible.
 598   StoreNode(Node *c, Node *mem, Node *adr, const TypePtr* at, Node *val, MemOrd mo)
 599     : MemNode(c, mem, adr, at, val), _mo(mo) {
 600     init_class_id(Class_Store);
 601   }
 602   StoreNode(Node *c, Node *mem, Node *adr, const TypePtr* at, Node *val, Node *oop_store, MemOrd mo)
 603     : MemNode(c, mem, adr, at, val, oop_store), _mo(mo) {
 604     init_class_id(Class_Store);
 605   }
 606 
 607   inline bool is_unordered() const { return !is_release(); }
 608   inline bool is_release() const {
 609     assert((_mo == unordered || _mo == release), "unexpected");
 610     return _mo == release;
 611   }
 612 
 613   // Conservatively release stores of object references in order to
 614   // ensure visibility of object initialization.
 615   static inline MemOrd release_if_reference(const BasicType t) {
 616 #ifdef AARCH64
 617     // AArch64 doesn't need a release store here because object
 618     // initialization contains the necessary barriers.
 619     return unordered;
 620 #else
 621     const MemOrd mo = (t == T_ARRAY ||
 622                        t == T_ADDRESS || // Might be the address of an object reference (`boxing').
 623                        t == T_OBJECT) ? release : unordered;
 624     return mo;
 625 #endif
 626   }
 627 
 628   // Polymorphic factory method
 629   //
 630   // We must ensure that stores of object references will be visible
 631   // only after the object's initialization. So the callers of this
 632   // procedure must indicate that the store requires `release'
 633   // semantics, if the stored value is an object reference that might
 634   // point to a new object and may become externally visible.
 635   static StoreNode* make(PhaseGVN& gvn, Node* c, Node* mem, Node* adr,
 636                          const TypePtr* at, Node* val, BasicType bt,
 637                          MemOrd mo, bool require_atomic_access = false);
 638 
 639   virtual uint hash() const;    // Check the type
 640 
 641   // If the store is to Field memory and the pointer is non-null, we can
 642   // zero out the control input.
 643   virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
 644 
 645   // Compute a new Type for this node.  Basically we just do the pre-check,
 646   // then call the virtual add() to set the type.
 647   virtual const Type* Value(PhaseGVN* phase) const;
 648 
 649   // Check for identity function on memory (Load then Store at same address)
 650   virtual Node* Identity(PhaseGVN* phase);
 651 
 652   // Do not match memory edge
 653   virtual uint match_edge(uint idx) const;
 654 
 655   virtual const Type *bottom_type() const;  // returns Type::MEMORY
 656 
 657   // Map a store opcode to its corresponding own opcode, trivially.
 658   virtual int store_Opcode() const { return Opcode(); }
 659 
 660   // have all possible loads of the value stored been optimized away?
 661   bool value_never_loaded(PhaseValues* phase) const;
 662 
 663   bool  has_reinterpret_variant(const Type* vt);
 664   Node* convert_to_reinterpret_store(PhaseGVN& gvn, Node* val, const Type* vt);
 665 
 666   MemBarNode* trailing_membar() const;
 667 };
 668 
 669 //------------------------------StoreBNode-------------------------------------
 670 // Store byte to memory
 671 class StoreBNode : public StoreNode {
 672 public:
 673   StoreBNode(Node *c, Node *mem, Node *adr, const TypePtr* at, Node *val, MemOrd mo)
 674     : StoreNode(c, mem, adr, at, val, mo) {}
 675   virtual int Opcode() const;
 676   virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
 677   virtual BasicType value_basic_type() const { return T_BYTE; }
 678 };
 679 
 680 //------------------------------StoreCNode-------------------------------------
 681 // Store char/short to memory
 682 class StoreCNode : public StoreNode {
 683 public:
 684   StoreCNode(Node *c, Node *mem, Node *adr, const TypePtr* at, Node *val, MemOrd mo)
 685     : StoreNode(c, mem, adr, at, val, mo) {}
 686   virtual int Opcode() const;
 687   virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
 688   virtual BasicType value_basic_type() const { return T_CHAR; }
 689 };
 690 
 691 //------------------------------StoreINode-------------------------------------
 692 // Store int to memory
 693 class StoreINode : public StoreNode {
 694 public:
 695   StoreINode(Node *c, Node *mem, Node *adr, const TypePtr* at, Node *val, MemOrd mo)
 696     : StoreNode(c, mem, adr, at, val, mo) {}
 697   virtual int Opcode() const;
 698   virtual BasicType value_basic_type() const { return T_INT; }
 699 };
 700 
 701 //------------------------------StoreLNode-------------------------------------
 702 // Store long to memory
 703 class StoreLNode : public StoreNode {
 704   virtual uint hash() const { return StoreNode::hash() + _require_atomic_access; }
 705   virtual bool cmp( const Node &n ) const {
 706     return _require_atomic_access == ((StoreLNode&)n)._require_atomic_access
 707       && StoreNode::cmp(n);
 708   }
 709   virtual uint size_of() const { return sizeof(*this); }
 710   const bool _require_atomic_access;  // is piecewise store forbidden?
 711 
 712 public:
 713   StoreLNode(Node *c, Node *mem, Node *adr, const TypePtr* at, Node *val, MemOrd mo, bool require_atomic_access = false)
 714     : StoreNode(c, mem, adr, at, val, mo), _require_atomic_access(require_atomic_access) {}
 715   virtual int Opcode() const;
 716   virtual BasicType value_basic_type() const { return T_LONG; }
 717   bool require_atomic_access() const { return _require_atomic_access; }
 718 
 719 #ifndef PRODUCT
 720   virtual void dump_spec(outputStream *st) const {
 721     StoreNode::dump_spec(st);
 722     if (_require_atomic_access)  st->print(" Atomic!");
 723   }
 724 #endif
 725 };
 726 
 727 // Special StoreL for flat stores that emits GC barriers for field at 'oop_off' in the backend
 728 class StoreLSpecialNode : public StoreNode {
 729 
 730 public:
 731   StoreLSpecialNode(Node* c, Node* mem, Node* adr, const TypePtr* at, Node* val, Node* oop_off, MemOrd mo)
 732     : StoreNode(c, mem, adr, at, val, mo) {
 733     set_mismatched_access();
 734     if (oop_off != nullptr) {
 735       add_req(oop_off);
 736     }
 737   }
 738   virtual int Opcode() const;
 739   virtual BasicType value_basic_type() const { return T_LONG; }
 740 
 741   virtual uint match_edge(uint idx) const { return idx == MemNode::Address ||
 742                                                    idx == MemNode::ValueIn ||
 743                                                    idx == MemNode::ValueIn + 1; }
 744 };
 745 
 746 //------------------------------StoreFNode-------------------------------------
 747 // Store float to memory
 748 class StoreFNode : public StoreNode {
 749 public:
 750   StoreFNode(Node *c, Node *mem, Node *adr, const TypePtr* at, Node *val, MemOrd mo)
 751     : StoreNode(c, mem, adr, at, val, mo) {}
 752   virtual int Opcode() const;
 753   virtual BasicType value_basic_type() const { return T_FLOAT; }
 754 };
 755 
 756 //------------------------------StoreDNode-------------------------------------
 757 // Store double to memory
 758 class StoreDNode : public StoreNode {
 759   virtual uint hash() const { return StoreNode::hash() + _require_atomic_access; }
 760   virtual bool cmp( const Node &n ) const {
 761     return _require_atomic_access == ((StoreDNode&)n)._require_atomic_access
 762       && StoreNode::cmp(n);
 763   }
 764   virtual uint size_of() const { return sizeof(*this); }
 765   const bool _require_atomic_access;  // is piecewise store forbidden?
 766 public:
 767   StoreDNode(Node *c, Node *mem, Node *adr, const TypePtr* at, Node *val,
 768              MemOrd mo, bool require_atomic_access = false)
 769     : StoreNode(c, mem, adr, at, val, mo), _require_atomic_access(require_atomic_access) {}
 770   virtual int Opcode() const;
 771   virtual BasicType value_basic_type() const { return T_DOUBLE; }
 772   bool require_atomic_access() const { return _require_atomic_access; }
 773 
 774 #ifndef PRODUCT
 775   virtual void dump_spec(outputStream *st) const {
 776     StoreNode::dump_spec(st);
 777     if (_require_atomic_access)  st->print(" Atomic!");
 778   }
 779 #endif
 780 
 781 };
 782 
 783 //------------------------------StorePNode-------------------------------------
 784 // Store pointer to memory
 785 class StorePNode : public StoreNode {
 786 public:
 787   StorePNode(Node *c, Node *mem, Node *adr, const TypePtr* at, Node *val, MemOrd mo)
 788     : StoreNode(c, mem, adr, at, val, mo) {}
 789   virtual int Opcode() const;
 790   virtual BasicType value_basic_type() const { return T_ADDRESS; }
 791 };
 792 
 793 //------------------------------StoreNNode-------------------------------------
 794 // Store narrow oop to memory
 795 class StoreNNode : public StoreNode {
 796 public:
 797   StoreNNode(Node *c, Node *mem, Node *adr, const TypePtr* at, Node *val, MemOrd mo)
 798     : StoreNode(c, mem, adr, at, val, mo) {}
 799   virtual int Opcode() const;
 800   virtual BasicType value_basic_type() const { return T_NARROWOOP; }
 801 };
 802 
 803 //------------------------------StoreNKlassNode--------------------------------------
 804 // Store narrow klass to memory
 805 class StoreNKlassNode : public StoreNNode {
 806 public:
 807   StoreNKlassNode(Node *c, Node *mem, Node *adr, const TypePtr* at, Node *val, MemOrd mo)
 808     : StoreNNode(c, mem, adr, at, val, mo) {}
 809   virtual int Opcode() const;
 810   virtual BasicType value_basic_type() const { return T_NARROWKLASS; }
 811 };
 812 
 813 //------------------------------SCMemProjNode---------------------------------------
 814 // This class defines a projection of the memory  state of a store conditional node.
 815 // These nodes return a value, but also update memory.
 816 class SCMemProjNode : public ProjNode {
 817 public:
 818   enum {SCMEMPROJCON = (uint)-2};
 819   SCMemProjNode( Node *src) : ProjNode( src, SCMEMPROJCON) { }
 820   virtual int Opcode() const;
 821   virtual bool      is_CFG() const  { return false; }
 822   virtual const Type *bottom_type() const {return Type::MEMORY;}
 823   virtual const TypePtr *adr_type() const {
 824     Node* ctrl = in(0);
 825     if (ctrl == nullptr)  return nullptr; // node is dead
 826     return ctrl->in(MemNode::Memory)->adr_type();
 827   }
 828   virtual uint ideal_reg() const { return 0;} // memory projections don't have a register
 829   virtual const Type* Value(PhaseGVN* phase) const;
 830 #ifndef PRODUCT
 831   virtual void dump_spec(outputStream *st) const {};
 832 #endif
 833 };
 834 
 835 //------------------------------LoadStoreNode---------------------------
 836 // Note: is_Mem() method returns 'true' for this class.
 837 class LoadStoreNode : public Node {
 838 private:
 839   const Type* const _type;      // What kind of value is loaded?
 840   const TypePtr* _adr_type;     // What kind of memory is being addressed?
 841   uint8_t _barrier_data;        // Bit field with barrier information
 842   virtual uint size_of() const; // Size is bigger
 843 public:
 844   LoadStoreNode( Node *c, Node *mem, Node *adr, Node *val, const TypePtr* at, const Type* rt, uint required );
 845   virtual bool depends_only_on_test() const { return false; }
 846   virtual uint match_edge(uint idx) const { return idx == MemNode::Address || idx == MemNode::ValueIn; }
 847 
 848   virtual const Type *bottom_type() const { return _type; }
 849   virtual uint ideal_reg() const;
 850   virtual const class TypePtr *adr_type() const { return _adr_type; }  // returns bottom_type of address
 851   virtual const Type* Value(PhaseGVN* phase) const;
 852 
 853   bool result_not_used() const;
 854   MemBarNode* trailing_membar() const;
 855 
 856   uint8_t barrier_data() { return _barrier_data; }
 857   void set_barrier_data(uint8_t barrier_data) { _barrier_data = barrier_data; }
 858 };
 859 
 860 class LoadStoreConditionalNode : public LoadStoreNode {
 861 public:
 862   enum {
 863     ExpectedIn = MemNode::ValueIn+1 // One more input than MemNode
 864   };
 865   LoadStoreConditionalNode(Node *c, Node *mem, Node *adr, Node *val, Node *ex);
 866   virtual const Type* Value(PhaseGVN* phase) const;
 867 };
 868 
 869 class CompareAndSwapNode : public LoadStoreConditionalNode {
 870 private:
 871   const MemNode::MemOrd _mem_ord;
 872 public:
 873   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) {}
 874   MemNode::MemOrd order() const {
 875     return _mem_ord;
 876   }
 877   virtual uint size_of() const { return sizeof(*this); }
 878 };
 879 
 880 class CompareAndExchangeNode : public LoadStoreNode {
 881 private:
 882   const MemNode::MemOrd _mem_ord;
 883 public:
 884   enum {
 885     ExpectedIn = MemNode::ValueIn+1 // One more input than MemNode
 886   };
 887   CompareAndExchangeNode( Node *c, Node *mem, Node *adr, Node *val, Node *ex, MemNode::MemOrd mem_ord, const TypePtr* at, const Type* t) :
 888     LoadStoreNode(c, mem, adr, val, at, t, 5), _mem_ord(mem_ord) {
 889      init_req(ExpectedIn, ex );
 890   }
 891 
 892   MemNode::MemOrd order() const {
 893     return _mem_ord;
 894   }
 895   virtual uint size_of() const { return sizeof(*this); }
 896 };
 897 
 898 //------------------------------CompareAndSwapBNode---------------------------
 899 class CompareAndSwapBNode : public CompareAndSwapNode {
 900 public:
 901   CompareAndSwapBNode( Node *c, Node *mem, Node *adr, Node *val, Node *ex, MemNode::MemOrd mem_ord) : CompareAndSwapNode(c, mem, adr, val, ex, mem_ord) { }
 902   virtual int Opcode() const;
 903 };
 904 
 905 //------------------------------CompareAndSwapSNode---------------------------
 906 class CompareAndSwapSNode : public CompareAndSwapNode {
 907 public:
 908   CompareAndSwapSNode( Node *c, Node *mem, Node *adr, Node *val, Node *ex, MemNode::MemOrd mem_ord) : CompareAndSwapNode(c, mem, adr, val, ex, mem_ord) { }
 909   virtual int Opcode() const;
 910 };
 911 
 912 //------------------------------CompareAndSwapINode---------------------------
 913 class CompareAndSwapINode : public CompareAndSwapNode {
 914 public:
 915   CompareAndSwapINode( Node *c, Node *mem, Node *adr, Node *val, Node *ex, MemNode::MemOrd mem_ord) : CompareAndSwapNode(c, mem, adr, val, ex, mem_ord) { }
 916   virtual int Opcode() const;
 917 };
 918 
 919 //------------------------------CompareAndSwapLNode---------------------------
 920 class CompareAndSwapLNode : public CompareAndSwapNode {
 921 public:
 922   CompareAndSwapLNode( Node *c, Node *mem, Node *adr, Node *val, Node *ex, MemNode::MemOrd mem_ord) : CompareAndSwapNode(c, mem, adr, val, ex, mem_ord) { }
 923   virtual int Opcode() const;
 924 };
 925 
 926 //------------------------------CompareAndSwapPNode---------------------------
 927 class CompareAndSwapPNode : public CompareAndSwapNode {
 928 public:
 929   CompareAndSwapPNode( Node *c, Node *mem, Node *adr, Node *val, Node *ex, MemNode::MemOrd mem_ord) : CompareAndSwapNode(c, mem, adr, val, ex, mem_ord) { }
 930   virtual int Opcode() const;
 931 };
 932 
 933 //------------------------------CompareAndSwapNNode---------------------------
 934 class CompareAndSwapNNode : public CompareAndSwapNode {
 935 public:
 936   CompareAndSwapNNode( Node *c, Node *mem, Node *adr, Node *val, Node *ex, MemNode::MemOrd mem_ord) : CompareAndSwapNode(c, mem, adr, val, ex, mem_ord) { }
 937   virtual int Opcode() const;
 938 };
 939 
 940 //------------------------------WeakCompareAndSwapBNode---------------------------
 941 class WeakCompareAndSwapBNode : public CompareAndSwapNode {
 942 public:
 943   WeakCompareAndSwapBNode( Node *c, Node *mem, Node *adr, Node *val, Node *ex, MemNode::MemOrd mem_ord) : CompareAndSwapNode(c, mem, adr, val, ex, mem_ord) { }
 944   virtual int Opcode() const;
 945 };
 946 
 947 //------------------------------WeakCompareAndSwapSNode---------------------------
 948 class WeakCompareAndSwapSNode : public CompareAndSwapNode {
 949 public:
 950   WeakCompareAndSwapSNode( Node *c, Node *mem, Node *adr, Node *val, Node *ex, MemNode::MemOrd mem_ord) : CompareAndSwapNode(c, mem, adr, val, ex, mem_ord) { }
 951   virtual int Opcode() const;
 952 };
 953 
 954 //------------------------------WeakCompareAndSwapINode---------------------------
 955 class WeakCompareAndSwapINode : public CompareAndSwapNode {
 956 public:
 957   WeakCompareAndSwapINode( Node *c, Node *mem, Node *adr, Node *val, Node *ex, MemNode::MemOrd mem_ord) : CompareAndSwapNode(c, mem, adr, val, ex, mem_ord) { }
 958   virtual int Opcode() const;
 959 };
 960 
 961 //------------------------------WeakCompareAndSwapLNode---------------------------
 962 class WeakCompareAndSwapLNode : public CompareAndSwapNode {
 963 public:
 964   WeakCompareAndSwapLNode( Node *c, Node *mem, Node *adr, Node *val, Node *ex, MemNode::MemOrd mem_ord) : CompareAndSwapNode(c, mem, adr, val, ex, mem_ord) { }
 965   virtual int Opcode() const;
 966 };
 967 
 968 //------------------------------WeakCompareAndSwapPNode---------------------------
 969 class WeakCompareAndSwapPNode : public CompareAndSwapNode {
 970 public:
 971   WeakCompareAndSwapPNode( Node *c, Node *mem, Node *adr, Node *val, Node *ex, MemNode::MemOrd mem_ord) : CompareAndSwapNode(c, mem, adr, val, ex, mem_ord) { }
 972   virtual int Opcode() const;
 973 };
 974 
 975 //------------------------------WeakCompareAndSwapNNode---------------------------
 976 class WeakCompareAndSwapNNode : public CompareAndSwapNode {
 977 public:
 978   WeakCompareAndSwapNNode( Node *c, Node *mem, Node *adr, Node *val, Node *ex, MemNode::MemOrd mem_ord) : CompareAndSwapNode(c, mem, adr, val, ex, mem_ord) { }
 979   virtual int Opcode() const;
 980 };
 981 
 982 //------------------------------CompareAndExchangeBNode---------------------------
 983 class CompareAndExchangeBNode : public CompareAndExchangeNode {
 984 public:
 985   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) { }
 986   virtual int Opcode() const;
 987 };
 988 
 989 
 990 //------------------------------CompareAndExchangeSNode---------------------------
 991 class CompareAndExchangeSNode : public CompareAndExchangeNode {
 992 public:
 993   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) { }
 994   virtual int Opcode() const;
 995 };
 996 
 997 //------------------------------CompareAndExchangeLNode---------------------------
 998 class CompareAndExchangeLNode : public CompareAndExchangeNode {
 999 public:
1000   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) { }
1001   virtual int Opcode() const;
1002 };
1003 
1004 
1005 //------------------------------CompareAndExchangeINode---------------------------
1006 class CompareAndExchangeINode : public CompareAndExchangeNode {
1007 public:
1008   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) { }
1009   virtual int Opcode() const;
1010 };
1011 
1012 
1013 //------------------------------CompareAndExchangePNode---------------------------
1014 class CompareAndExchangePNode : public CompareAndExchangeNode {
1015 public:
1016   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) { }
1017   virtual int Opcode() const;
1018 };
1019 
1020 //------------------------------CompareAndExchangeNNode---------------------------
1021 class CompareAndExchangeNNode : public CompareAndExchangeNode {
1022 public:
1023   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) { }
1024   virtual int Opcode() const;
1025 };
1026 
1027 //------------------------------GetAndAddBNode---------------------------
1028 class GetAndAddBNode : public LoadStoreNode {
1029 public:
1030   GetAndAddBNode( Node *c, Node *mem, Node *adr, Node *val, const TypePtr* at ) : LoadStoreNode(c, mem, adr, val, at, TypeInt::BYTE, 4) { }
1031   virtual int Opcode() const;
1032 };
1033 
1034 //------------------------------GetAndAddSNode---------------------------
1035 class GetAndAddSNode : public LoadStoreNode {
1036 public:
1037   GetAndAddSNode( Node *c, Node *mem, Node *adr, Node *val, const TypePtr* at ) : LoadStoreNode(c, mem, adr, val, at, TypeInt::SHORT, 4) { }
1038   virtual int Opcode() const;
1039 };
1040 
1041 //------------------------------GetAndAddINode---------------------------
1042 class GetAndAddINode : public LoadStoreNode {
1043 public:
1044   GetAndAddINode( Node *c, Node *mem, Node *adr, Node *val, const TypePtr* at ) : LoadStoreNode(c, mem, adr, val, at, TypeInt::INT, 4) { }
1045   virtual int Opcode() const;
1046 };
1047 
1048 //------------------------------GetAndAddLNode---------------------------
1049 class GetAndAddLNode : public LoadStoreNode {
1050 public:
1051   GetAndAddLNode( Node *c, Node *mem, Node *adr, Node *val, const TypePtr* at ) : LoadStoreNode(c, mem, adr, val, at, TypeLong::LONG, 4) { }
1052   virtual int Opcode() const;
1053 };
1054 
1055 //------------------------------GetAndSetBNode---------------------------
1056 class GetAndSetBNode : public LoadStoreNode {
1057 public:
1058   GetAndSetBNode( Node *c, Node *mem, Node *adr, Node *val, const TypePtr* at ) : LoadStoreNode(c, mem, adr, val, at, TypeInt::BYTE, 4) { }
1059   virtual int Opcode() const;
1060 };
1061 
1062 //------------------------------GetAndSetSNode---------------------------
1063 class GetAndSetSNode : public LoadStoreNode {
1064 public:
1065   GetAndSetSNode( Node *c, Node *mem, Node *adr, Node *val, const TypePtr* at ) : LoadStoreNode(c, mem, adr, val, at, TypeInt::SHORT, 4) { }
1066   virtual int Opcode() const;
1067 };
1068 
1069 //------------------------------GetAndSetINode---------------------------
1070 class GetAndSetINode : public LoadStoreNode {
1071 public:
1072   GetAndSetINode( Node *c, Node *mem, Node *adr, Node *val, const TypePtr* at ) : LoadStoreNode(c, mem, adr, val, at, TypeInt::INT, 4) { }
1073   virtual int Opcode() const;
1074 };
1075 
1076 //------------------------------GetAndSetLNode---------------------------
1077 class GetAndSetLNode : public LoadStoreNode {
1078 public:
1079   GetAndSetLNode( Node *c, Node *mem, Node *adr, Node *val, const TypePtr* at ) : LoadStoreNode(c, mem, adr, val, at, TypeLong::LONG, 4) { }
1080   virtual int Opcode() const;
1081 };
1082 
1083 //------------------------------GetAndSetPNode---------------------------
1084 class GetAndSetPNode : public LoadStoreNode {
1085 public:
1086   GetAndSetPNode( Node *c, Node *mem, Node *adr, Node *val, const TypePtr* at, const Type* t ) : LoadStoreNode(c, mem, adr, val, at, t, 4) { }
1087   virtual int Opcode() const;
1088 };
1089 
1090 //------------------------------GetAndSetNNode---------------------------
1091 class GetAndSetNNode : public LoadStoreNode {
1092 public:
1093   GetAndSetNNode( Node *c, Node *mem, Node *adr, Node *val, const TypePtr* at, const Type* t ) : LoadStoreNode(c, mem, adr, val, at, t, 4) { }
1094   virtual int Opcode() const;
1095 };
1096 
1097 //------------------------------ClearArray-------------------------------------
1098 class ClearArrayNode: public Node {
1099 private:
1100   bool _is_large;
1101   bool _word_copy_only;
1102 public:
1103   ClearArrayNode( Node *ctrl, Node *arymem, Node *word_cnt, Node *base, Node* val, bool is_large)
1104     : Node(ctrl, arymem, word_cnt, base, val), _is_large(is_large),
1105       _word_copy_only(val->bottom_type()->isa_long() && (!val->bottom_type()->is_long()->is_con() || val->bottom_type()->is_long()->get_con() != 0)) {
1106     init_class_id(Class_ClearArray);
1107   }
1108   virtual int         Opcode() const;
1109   virtual const Type *bottom_type() const { return Type::MEMORY; }
1110   // ClearArray modifies array elements, and so affects only the
1111   // array memory addressed by the bottom_type of its base address.
1112   virtual const class TypePtr *adr_type() const;
1113   virtual Node* Identity(PhaseGVN* phase);
1114   virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
1115   virtual uint match_edge(uint idx) const;
1116   bool is_large() const { return _is_large; }
1117   bool word_copy_only() const { return _word_copy_only; }
1118   virtual uint size_of() const { return sizeof(ClearArrayNode); }
1119   virtual uint hash() const { return Node::hash() + _is_large; }
1120   virtual bool cmp(const Node& n) const {
1121     return Node::cmp(n) && _is_large == ((ClearArrayNode&)n).is_large();
1122   }
1123 
1124   // Clear the given area of an object or array.
1125   // The start offset must always be aligned mod BytesPerInt.
1126   // The end offset must always be aligned mod BytesPerLong.
1127   // Return the new memory.
1128   static Node* clear_memory(Node* control, Node* mem, Node* dest,
1129                             Node* val,
1130                             Node* raw_val,
1131                             intptr_t start_offset,
1132                             intptr_t end_offset,
1133                             PhaseGVN* phase);
1134   static Node* clear_memory(Node* control, Node* mem, Node* dest,
1135                             Node* val,
1136                             Node* raw_val,
1137                             intptr_t start_offset,
1138                             Node* end_offset,
1139                             PhaseGVN* phase);
1140   static Node* clear_memory(Node* control, Node* mem, Node* dest,
1141                             Node* raw_val,
1142                             Node* start_offset,
1143                             Node* end_offset,
1144                             PhaseGVN* phase);
1145   // Return allocation input memory edge if it is different instance
1146   // or itself if it is the one we are looking for.
1147   static bool step_through(Node** np, uint instance_id, PhaseValues* phase);
1148 };
1149 
1150 //------------------------------MemBar-----------------------------------------
1151 // There are different flavors of Memory Barriers to match the Java Memory
1152 // Model.  Monitor-enter and volatile-load act as Acquires: no following ref
1153 // can be moved to before them.  We insert a MemBar-Acquire after a FastLock or
1154 // volatile-load.  Monitor-exit and volatile-store act as Release: no
1155 // preceding ref can be moved to after them.  We insert a MemBar-Release
1156 // before a FastUnlock or volatile-store.  All volatiles need to be
1157 // serialized, so we follow all volatile-stores with a MemBar-Volatile to
1158 // separate it from any following volatile-load.
1159 class MemBarNode: public MultiNode {
1160   virtual uint hash() const ;                  // { return NO_HASH; }
1161   virtual bool cmp( const Node &n ) const ;    // Always fail, except on self
1162 
1163   virtual uint size_of() const { return sizeof(*this); }
1164   // Memory type this node is serializing.  Usually either rawptr or bottom.
1165   const TypePtr* _adr_type;
1166 
1167   // How is this membar related to a nearby memory access?
1168   enum {
1169     Standalone,
1170     TrailingLoad,
1171     TrailingStore,
1172     LeadingStore,
1173     TrailingLoadStore,
1174     LeadingLoadStore,
1175     TrailingExpandedArrayCopy
1176   } _kind;
1177 
1178 #ifdef ASSERT
1179   uint _pair_idx;
1180 #endif
1181 
1182 public:
1183   enum {
1184     Precedent = TypeFunc::Parms  // optional edge to force precedence
1185   };
1186   MemBarNode(Compile* C, int alias_idx, Node* precedent);
1187   virtual int Opcode() const = 0;
1188   virtual const class TypePtr *adr_type() const { return _adr_type; }
1189   virtual const Type* Value(PhaseGVN* phase) const;
1190   virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
1191   virtual uint match_edge(uint idx) const { return 0; }
1192   virtual const Type *bottom_type() const { return TypeTuple::MEMBAR; }
1193   virtual Node *match(const ProjNode *proj, const Matcher *m, const RegMask* mask);
1194   // Factory method.  Builds a wide or narrow membar.
1195   // Optional 'precedent' becomes an extra edge if not null.
1196   static MemBarNode* make(Compile* C, int opcode,
1197                           int alias_idx = Compile::AliasIdxBot,
1198                           Node* precedent = nullptr);
1199 
1200   MemBarNode* trailing_membar() const;
1201   MemBarNode* leading_membar() const;
1202 
1203   void set_trailing_load() { _kind = TrailingLoad; }
1204   bool trailing_load() const { return _kind == TrailingLoad; }
1205   bool trailing_store() const { return _kind == TrailingStore; }
1206   bool leading_store() const { return _kind == LeadingStore; }
1207   bool trailing_load_store() const { return _kind == TrailingLoadStore; }
1208   bool leading_load_store() const { return _kind == LeadingLoadStore; }
1209   bool trailing() const { return _kind == TrailingLoad || _kind == TrailingStore || _kind == TrailingLoadStore; }
1210   bool leading() const { return _kind == LeadingStore || _kind == LeadingLoadStore; }
1211   bool standalone() const { return _kind == Standalone; }
1212   void set_trailing_expanded_array_copy() { _kind = TrailingExpandedArrayCopy; }
1213   bool trailing_expanded_array_copy() const { return _kind == TrailingExpandedArrayCopy; }
1214 
1215   static void set_store_pair(MemBarNode* leading, MemBarNode* trailing);
1216   static void set_load_store_pair(MemBarNode* leading, MemBarNode* trailing);
1217 
1218   void remove(PhaseIterGVN *igvn);
1219 };
1220 
1221 // "Acquire" - no following ref can move before (but earlier refs can
1222 // follow, like an early Load stalled in cache).  Requires multi-cpu
1223 // visibility.  Inserted after a volatile load.
1224 class MemBarAcquireNode: public MemBarNode {
1225 public:
1226   MemBarAcquireNode(Compile* C, int alias_idx, Node* precedent)
1227     : MemBarNode(C, alias_idx, precedent) {}
1228   virtual int Opcode() const;
1229 };
1230 
1231 // "Acquire" - no following ref can move before (but earlier refs can
1232 // follow, like an early Load stalled in cache).  Requires multi-cpu
1233 // visibility.  Inserted independent of any load, as required
1234 // for intrinsic Unsafe.loadFence().
1235 class LoadFenceNode: public MemBarNode {
1236 public:
1237   LoadFenceNode(Compile* C, int alias_idx, Node* precedent)
1238     : MemBarNode(C, alias_idx, precedent) {}
1239   virtual int Opcode() const;
1240 };
1241 
1242 // "Release" - no earlier ref can move after (but later refs can move
1243 // up, like a speculative pipelined cache-hitting Load).  Requires
1244 // multi-cpu visibility.  Inserted before a volatile store.
1245 class MemBarReleaseNode: public MemBarNode {
1246 public:
1247   MemBarReleaseNode(Compile* C, int alias_idx, Node* precedent)
1248     : MemBarNode(C, alias_idx, precedent) {}
1249   virtual int Opcode() const;
1250 };
1251 
1252 // "Release" - no earlier ref can move after (but later refs can move
1253 // up, like a speculative pipelined cache-hitting Load).  Requires
1254 // multi-cpu visibility.  Inserted independent of any store, as required
1255 // for intrinsic Unsafe.storeFence().
1256 class StoreFenceNode: public MemBarNode {
1257 public:
1258   StoreFenceNode(Compile* C, int alias_idx, Node* precedent)
1259     : MemBarNode(C, alias_idx, precedent) {}
1260   virtual int Opcode() const;
1261 };
1262 
1263 // "Acquire" - no following ref can move before (but earlier refs can
1264 // follow, like an early Load stalled in cache).  Requires multi-cpu
1265 // visibility.  Inserted after a FastLock.
1266 class MemBarAcquireLockNode: public MemBarNode {
1267 public:
1268   MemBarAcquireLockNode(Compile* C, int alias_idx, Node* precedent)
1269     : MemBarNode(C, alias_idx, precedent) {}
1270   virtual int Opcode() const;
1271 };
1272 
1273 // "Release" - no earlier ref can move after (but later refs can move
1274 // up, like a speculative pipelined cache-hitting Load).  Requires
1275 // multi-cpu visibility.  Inserted before a FastUnLock.
1276 class MemBarReleaseLockNode: public MemBarNode {
1277 public:
1278   MemBarReleaseLockNode(Compile* C, int alias_idx, Node* precedent)
1279     : MemBarNode(C, alias_idx, precedent) {}
1280   virtual int Opcode() const;
1281 };
1282 
1283 class MemBarStoreStoreNode: public MemBarNode {
1284 public:
1285   MemBarStoreStoreNode(Compile* C, int alias_idx, Node* precedent)
1286     : MemBarNode(C, alias_idx, precedent) {
1287     init_class_id(Class_MemBarStoreStore);
1288   }
1289   virtual int Opcode() const;
1290 };
1291 
1292 class StoreStoreFenceNode: public MemBarNode {
1293 public:
1294   StoreStoreFenceNode(Compile* C, int alias_idx, Node* precedent)
1295     : MemBarNode(C, alias_idx, precedent) {}
1296   virtual int Opcode() const;
1297 };
1298 
1299 // Ordering between a volatile store and a following volatile load.
1300 // Requires multi-CPU visibility?
1301 class MemBarVolatileNode: public MemBarNode {
1302 public:
1303   MemBarVolatileNode(Compile* C, int alias_idx, Node* precedent)
1304     : MemBarNode(C, alias_idx, precedent) {}
1305   virtual int Opcode() const;
1306 };
1307 
1308 // Ordering within the same CPU.  Used to order unsafe memory references
1309 // inside the compiler when we lack alias info.  Not needed "outside" the
1310 // compiler because the CPU does all the ordering for us.
1311 class MemBarCPUOrderNode: public MemBarNode {
1312 public:
1313   MemBarCPUOrderNode(Compile* C, int alias_idx, Node* precedent)
1314     : MemBarNode(C, alias_idx, precedent) {}
1315   virtual int Opcode() const;
1316   virtual uint ideal_reg() const { return 0; } // not matched in the AD file
1317 };
1318 
1319 class OnSpinWaitNode: public MemBarNode {
1320 public:
1321   OnSpinWaitNode(Compile* C, int alias_idx, Node* precedent)
1322     : MemBarNode(C, alias_idx, precedent) {}
1323   virtual int Opcode() const;
1324 };
1325 
1326 // Isolation of object setup after an AllocateNode and before next safepoint.
1327 // (See comment in memnode.cpp near InitializeNode::InitializeNode for semantics.)
1328 class InitializeNode: public MemBarNode {
1329   friend class AllocateNode;
1330 
1331   enum {
1332     Incomplete    = 0,
1333     Complete      = 1,
1334     WithArraycopy = 2
1335   };
1336   int _is_complete;
1337 
1338   bool _does_not_escape;
1339 
1340 public:
1341   enum {
1342     Control    = TypeFunc::Control,
1343     Memory     = TypeFunc::Memory,     // MergeMem for states affected by this op
1344     RawAddress = TypeFunc::Parms+0,    // the newly-allocated raw address
1345     RawStores  = TypeFunc::Parms+1     // zero or more stores (or TOP)
1346   };
1347 
1348   InitializeNode(Compile* C, int adr_type, Node* rawoop);
1349   virtual int Opcode() const;
1350   virtual uint size_of() const { return sizeof(*this); }
1351   virtual uint ideal_reg() const { return 0; } // not matched in the AD file
1352   virtual const RegMask &in_RegMask(uint) const;  // mask for RawAddress
1353 
1354   // Manage incoming memory edges via a MergeMem on in(Memory):
1355   Node* memory(uint alias_idx);
1356 
1357   // The raw memory edge coming directly from the Allocation.
1358   // The contents of this memory are *always* all-zero-bits.
1359   Node* zero_memory() { return memory(Compile::AliasIdxRaw); }
1360 
1361   // Return the corresponding allocation for this initialization (or null if none).
1362   // (Note: Both InitializeNode::allocation and AllocateNode::initialization
1363   // are defined in graphKit.cpp, which sets up the bidirectional relation.)
1364   AllocateNode* allocation();
1365 
1366   // Anything other than zeroing in this init?
1367   bool is_non_zero();
1368 
1369   // An InitializeNode must completed before macro expansion is done.
1370   // Completion requires that the AllocateNode must be followed by
1371   // initialization of the new memory to zero, then to any initializers.
1372   bool is_complete() { return _is_complete != Incomplete; }
1373   bool is_complete_with_arraycopy() { return (_is_complete & WithArraycopy) != 0; }
1374 
1375   // Mark complete.  (Must not yet be complete.)
1376   void set_complete(PhaseGVN* phase);
1377   void set_complete_with_arraycopy() { _is_complete = Complete | WithArraycopy; }
1378 
1379   bool does_not_escape() { return _does_not_escape; }
1380   void set_does_not_escape() { _does_not_escape = true; }
1381 
1382 #ifdef ASSERT
1383   // ensure all non-degenerate stores are ordered and non-overlapping
1384   bool stores_are_sane(PhaseValues* phase);
1385 #endif //ASSERT
1386 
1387   // See if this store can be captured; return offset where it initializes.
1388   // Return 0 if the store cannot be moved (any sort of problem).
1389   intptr_t can_capture_store(StoreNode* st, PhaseGVN* phase, bool can_reshape);
1390 
1391   // Capture another store; reformat it to write my internal raw memory.
1392   // Return the captured copy, else null if there is some sort of problem.
1393   Node* capture_store(StoreNode* st, intptr_t start, PhaseGVN* phase, bool can_reshape);
1394 
1395   // Find captured store which corresponds to the range [start..start+size).
1396   // Return my own memory projection (meaning the initial zero bits)
1397   // if there is no such store.  Return null if there is a problem.
1398   Node* find_captured_store(intptr_t start, int size_in_bytes, PhaseValues* phase);
1399 
1400   // Called when the associated AllocateNode is expanded into CFG.
1401   Node* complete_stores(Node* rawctl, Node* rawmem, Node* rawptr,
1402                         intptr_t header_size, Node* size_in_bytes,
1403                         PhaseIterGVN* phase);
1404 
1405  private:
1406   void remove_extra_zeroes();
1407 
1408   // Find out where a captured store should be placed (or already is placed).
1409   int captured_store_insertion_point(intptr_t start, int size_in_bytes,
1410                                      PhaseValues* phase);
1411 
1412   static intptr_t get_store_offset(Node* st, PhaseValues* phase);
1413 
1414   Node* make_raw_address(intptr_t offset, PhaseGVN* phase);
1415 
1416   bool detect_init_independence(Node* value, PhaseGVN* phase);
1417 
1418   void coalesce_subword_stores(intptr_t header_size, Node* size_in_bytes,
1419                                PhaseGVN* phase);
1420 
1421   intptr_t find_next_fullword_store(uint i, PhaseGVN* phase);
1422 };
1423 
1424 //------------------------------MergeMem---------------------------------------
1425 // (See comment in memnode.cpp near MergeMemNode::MergeMemNode for semantics.)
1426 class MergeMemNode: public Node {
1427   virtual uint hash() const ;                  // { return NO_HASH; }
1428   virtual bool cmp( const Node &n ) const ;    // Always fail, except on self
1429   friend class MergeMemStream;
1430   MergeMemNode(Node* def);  // clients use MergeMemNode::make
1431 
1432 public:
1433   // If the input is a whole memory state, clone it with all its slices intact.
1434   // Otherwise, make a new memory state with just that base memory input.
1435   // In either case, the result is a newly created MergeMem.
1436   static MergeMemNode* make(Node* base_memory);
1437 
1438   virtual int Opcode() const;
1439   virtual Node* Identity(PhaseGVN* phase);
1440   virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
1441   virtual uint ideal_reg() const { return NotAMachineReg; }
1442   virtual uint match_edge(uint idx) const { return 0; }
1443   virtual const RegMask &out_RegMask() const;
1444   virtual const Type *bottom_type() const { return Type::MEMORY; }
1445   virtual const TypePtr *adr_type() const { return TypePtr::BOTTOM; }
1446   // sparse accessors
1447   // Fetch the previously stored "set_memory_at", or else the base memory.
1448   // (Caller should clone it if it is a phi-nest.)
1449   Node* memory_at(uint alias_idx) const;
1450   // set the memory, regardless of its previous value
1451   void set_memory_at(uint alias_idx, Node* n);
1452   // the "base" is the memory that provides the non-finite support
1453   Node* base_memory() const       { return in(Compile::AliasIdxBot); }
1454   // warning: setting the base can implicitly set any of the other slices too
1455   void set_base_memory(Node* def);
1456   // sentinel value which denotes a copy of the base memory:
1457   Node*   empty_memory() const    { return in(Compile::AliasIdxTop); }
1458   static Node* make_empty_memory(); // where the sentinel comes from
1459   bool is_empty_memory(Node* n) const { assert((n == empty_memory()) == n->is_top(), "sanity"); return n->is_top(); }
1460   // hook for the iterator, to perform any necessary setup
1461   void iteration_setup(const MergeMemNode* other = nullptr);
1462   // push sentinels until I am at least as long as the other (semantic no-op)
1463   void grow_to_match(const MergeMemNode* other);
1464   bool verify_sparse() const PRODUCT_RETURN0;
1465 #ifndef PRODUCT
1466   virtual void dump_spec(outputStream *st) const;
1467 #endif
1468 };
1469 
1470 class MergeMemStream : public StackObj {
1471  private:
1472   MergeMemNode*       _mm;
1473   const MergeMemNode* _mm2;  // optional second guy, contributes non-empty iterations
1474   Node*               _mm_base;  // loop-invariant base memory of _mm
1475   int                 _idx;
1476   int                 _cnt;
1477   Node*               _mem;
1478   Node*               _mem2;
1479   int                 _cnt2;
1480 
1481   void init(MergeMemNode* mm, const MergeMemNode* mm2 = nullptr) {
1482     // subsume_node will break sparseness at times, whenever a memory slice
1483     // folds down to a copy of the base ("fat") memory.  In such a case,
1484     // the raw edge will update to base, although it should be top.
1485     // This iterator will recognize either top or base_memory as an
1486     // "empty" slice.  See is_empty, is_empty2, and next below.
1487     //
1488     // The sparseness property is repaired in MergeMemNode::Ideal.
1489     // As long as access to a MergeMem goes through this iterator
1490     // or the memory_at accessor, flaws in the sparseness will
1491     // never be observed.
1492     //
1493     // Also, iteration_setup repairs sparseness.
1494     assert(mm->verify_sparse(), "please, no dups of base");
1495     assert(mm2==nullptr || mm2->verify_sparse(), "please, no dups of base");
1496 
1497     _mm  = mm;
1498     _mm_base = mm->base_memory();
1499     _mm2 = mm2;
1500     _cnt = mm->req();
1501     _idx = Compile::AliasIdxBot-1; // start at the base memory
1502     _mem = nullptr;
1503     _mem2 = nullptr;
1504   }
1505 
1506 #ifdef ASSERT
1507   Node* check_memory() const {
1508     if (at_base_memory())
1509       return _mm->base_memory();
1510     else if ((uint)_idx < _mm->req() && !_mm->in(_idx)->is_top())
1511       return _mm->memory_at(_idx);
1512     else
1513       return _mm_base;
1514   }
1515   Node* check_memory2() const {
1516     return at_base_memory()? _mm2->base_memory(): _mm2->memory_at(_idx);
1517   }
1518 #endif
1519 
1520   static bool match_memory(Node* mem, const MergeMemNode* mm, int idx) PRODUCT_RETURN0;
1521   void assert_synch() const {
1522     assert(!_mem || _idx >= _cnt || match_memory(_mem, _mm, _idx),
1523            "no side-effects except through the stream");
1524   }
1525 
1526  public:
1527 
1528   // expected usages:
1529   // for (MergeMemStream mms(mem->is_MergeMem()); next_non_empty(); ) { ... }
1530   // for (MergeMemStream mms(mem1, mem2); next_non_empty2(); ) { ... }
1531 
1532   // iterate over one merge
1533   MergeMemStream(MergeMemNode* mm) {
1534     mm->iteration_setup();
1535     init(mm);
1536     DEBUG_ONLY(_cnt2 = 999);
1537   }
1538   // iterate in parallel over two merges
1539   // only iterates through non-empty elements of mm2
1540   MergeMemStream(MergeMemNode* mm, const MergeMemNode* mm2) {
1541     assert(mm2, "second argument must be a MergeMem also");
1542     ((MergeMemNode*)mm2)->iteration_setup();  // update hidden state
1543     mm->iteration_setup(mm2);
1544     init(mm, mm2);
1545     _cnt2 = mm2->req();
1546   }
1547 #ifdef ASSERT
1548   ~MergeMemStream() {
1549     assert_synch();
1550   }
1551 #endif
1552 
1553   MergeMemNode* all_memory() const {
1554     return _mm;
1555   }
1556   Node* base_memory() const {
1557     assert(_mm_base == _mm->base_memory(), "no update to base memory, please");
1558     return _mm_base;
1559   }
1560   const MergeMemNode* all_memory2() const {
1561     assert(_mm2 != nullptr, "");
1562     return _mm2;
1563   }
1564   bool at_base_memory() const {
1565     return _idx == Compile::AliasIdxBot;
1566   }
1567   int alias_idx() const {
1568     assert(_mem, "must call next 1st");
1569     return _idx;
1570   }
1571 
1572   const TypePtr* adr_type() const {
1573     return Compile::current()->get_adr_type(alias_idx());
1574   }
1575 
1576   const TypePtr* adr_type(Compile* C) const {
1577     return C->get_adr_type(alias_idx());
1578   }
1579   bool is_empty() const {
1580     assert(_mem, "must call next 1st");
1581     assert(_mem->is_top() == (_mem==_mm->empty_memory()), "correct sentinel");
1582     return _mem->is_top();
1583   }
1584   bool is_empty2() const {
1585     assert(_mem2, "must call next 1st");
1586     assert(_mem2->is_top() == (_mem2==_mm2->empty_memory()), "correct sentinel");
1587     return _mem2->is_top();
1588   }
1589   Node* memory() const {
1590     assert(!is_empty(), "must not be empty");
1591     assert_synch();
1592     return _mem;
1593   }
1594   // get the current memory, regardless of empty or non-empty status
1595   Node* force_memory() const {
1596     assert(!is_empty() || !at_base_memory(), "");
1597     // Use _mm_base to defend against updates to _mem->base_memory().
1598     Node *mem = _mem->is_top() ? _mm_base : _mem;
1599     assert(mem == check_memory(), "");
1600     return mem;
1601   }
1602   Node* memory2() const {
1603     assert(_mem2 == check_memory2(), "");
1604     return _mem2;
1605   }
1606   void set_memory(Node* mem) {
1607     if (at_base_memory()) {
1608       // Note that this does not change the invariant _mm_base.
1609       _mm->set_base_memory(mem);
1610     } else {
1611       _mm->set_memory_at(_idx, mem);
1612     }
1613     _mem = mem;
1614     assert_synch();
1615   }
1616 
1617   // Recover from a side effect to the MergeMemNode.
1618   void set_memory() {
1619     _mem = _mm->in(_idx);
1620   }
1621 
1622   bool next()  { return next(false); }
1623   bool next2() { return next(true); }
1624 
1625   bool next_non_empty()  { return next_non_empty(false); }
1626   bool next_non_empty2() { return next_non_empty(true); }
1627   // next_non_empty2 can yield states where is_empty() is true
1628 
1629  private:
1630   // find the next item, which might be empty
1631   bool next(bool have_mm2) {
1632     assert((_mm2 != nullptr) == have_mm2, "use other next");
1633     assert_synch();
1634     if (++_idx < _cnt) {
1635       // Note:  This iterator allows _mm to be non-sparse.
1636       // It behaves the same whether _mem is top or base_memory.
1637       _mem = _mm->in(_idx);
1638       if (have_mm2)
1639         _mem2 = _mm2->in((_idx < _cnt2) ? _idx : Compile::AliasIdxTop);
1640       return true;
1641     }
1642     return false;
1643   }
1644 
1645   // find the next non-empty item
1646   bool next_non_empty(bool have_mm2) {
1647     while (next(have_mm2)) {
1648       if (!is_empty()) {
1649         // make sure _mem2 is filled in sensibly
1650         if (have_mm2 && _mem2->is_top())  _mem2 = _mm2->base_memory();
1651         return true;
1652       } else if (have_mm2 && !is_empty2()) {
1653         return true;   // is_empty() == true
1654       }
1655     }
1656     return false;
1657   }
1658 };
1659 
1660 // cachewb node for guaranteeing writeback of the cache line at a
1661 // given address to (non-volatile) RAM
1662 class CacheWBNode : public Node {
1663 public:
1664   CacheWBNode(Node *ctrl, Node *mem, Node *addr) : Node(ctrl, mem, addr) {}
1665   virtual int Opcode() const;
1666   virtual uint ideal_reg() const { return NotAMachineReg; }
1667   virtual uint match_edge(uint idx) const { return (idx == 2); }
1668   virtual const TypePtr *adr_type() const { return TypePtr::BOTTOM; }
1669   virtual const Type *bottom_type() const { return Type::MEMORY; }
1670 };
1671 
1672 // cachewb pre sync node for ensuring that writebacks are serialised
1673 // relative to preceding or following stores
1674 class CacheWBPreSyncNode : public Node {
1675 public:
1676   CacheWBPreSyncNode(Node *ctrl, Node *mem) : Node(ctrl, mem) {}
1677   virtual int Opcode() const;
1678   virtual uint ideal_reg() const { return NotAMachineReg; }
1679   virtual uint match_edge(uint idx) const { return false; }
1680   virtual const TypePtr *adr_type() const { return TypePtr::BOTTOM; }
1681   virtual const Type *bottom_type() const { return Type::MEMORY; }
1682 };
1683 
1684 // cachewb pre sync node for ensuring that writebacks are serialised
1685 // relative to preceding or following stores
1686 class CacheWBPostSyncNode : public Node {
1687 public:
1688   CacheWBPostSyncNode(Node *ctrl, Node *mem) : Node(ctrl, mem) {}
1689   virtual int Opcode() const;
1690   virtual uint ideal_reg() const { return NotAMachineReg; }
1691   virtual uint match_edge(uint idx) const { return false; }
1692   virtual const TypePtr *adr_type() const { return TypePtr::BOTTOM; }
1693   virtual const Type *bottom_type() const { return Type::MEMORY; }
1694 };
1695 
1696 //------------------------------Prefetch---------------------------------------
1697 
1698 // Allocation prefetch which may fault, TLAB size have to be adjusted.
1699 class PrefetchAllocationNode : public Node {
1700 public:
1701   PrefetchAllocationNode(Node *mem, Node *adr) : Node(nullptr,mem,adr) {}
1702   virtual int Opcode() const;
1703   virtual uint ideal_reg() const { return NotAMachineReg; }
1704   virtual uint match_edge(uint idx) const { return idx==2; }
1705   virtual const Type *bottom_type() const { return ( AllocatePrefetchStyle == 3 ) ? Type::MEMORY : Type::ABIO; }
1706 };
1707 
1708 #endif // SHARE_OPTO_MEMNODE_HPP