1 /*
   2  * Copyright (c) 1997, 2025, Oracle and/or its affiliates. All rights reserved.
   3  * Copyright (c) 2024, Alibaba Group Holding Limited. All rights reserved.
   4  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   5  *
   6  * This code is free software; you can redistribute it and/or modify it
   7  * under the terms of the GNU General Public License version 2 only, as
   8  * published by the Free Software Foundation.
   9  *
  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).
  15  *
  16  * You should have received a copy of the GNU General Public License version
  17  * 2 along with this work; if not, write to the Free Software Foundation,
  18  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  19  *
  20  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  21  * or visit www.oracle.com if you need additional information or have any
  22  * questions.
  23  *
  24  */
  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 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 uint ideal_reg() const { return 0;} // memory projections don't have a register
 824   virtual const Type* Value(PhaseGVN* phase) const;
 825 #ifndef PRODUCT
 826   virtual void dump_spec(outputStream *st) const {};
 827 #endif
 828 };
 829 
 830 //------------------------------LoadStoreNode---------------------------
 831 // Note: is_Mem() method returns 'true' for this class.
 832 class LoadStoreNode : public Node {
 833 private:
 834   const Type* const _type;      // What kind of value is loaded?
 835   uint8_t _barrier_data;        // Bit field with barrier information
 836   virtual uint size_of() const; // Size is bigger
 837 #ifdef ASSERT
 838   const TypePtr* _adr_type;     // What kind of memory is being addressed?
 839 #endif // ASSERT
 840 public:
 841   LoadStoreNode( Node *c, Node *mem, Node *adr, Node *val, const TypePtr* at, const Type* rt, uint required );
 842   virtual bool depends_only_on_test() const { return false; }
 843   virtual uint match_edge(uint idx) const { return idx == MemNode::Address || idx == MemNode::ValueIn; }
 844 
 845   virtual const Type *bottom_type() const { return _type; }
 846   virtual uint ideal_reg() const;
 847   virtual const TypePtr* adr_type() const;
 848   virtual const Type* Value(PhaseGVN* phase) const;
 849 
 850   bool result_not_used() const;
 851   MemBarNode* trailing_membar() const;
 852 
 853   uint8_t barrier_data() { return _barrier_data; }
 854   void set_barrier_data(uint8_t barrier_data) { _barrier_data = barrier_data; }
 855 };
 856 
 857 class LoadStoreConditionalNode : public LoadStoreNode {
 858 public:
 859   enum {
 860     ExpectedIn = MemNode::ValueIn+1 // One more input than MemNode
 861   };
 862   LoadStoreConditionalNode(Node *c, Node *mem, Node *adr, Node *val, Node *ex);
 863   virtual const Type* Value(PhaseGVN* phase) const;
 864 };
 865 
 866 class CompareAndSwapNode : public LoadStoreConditionalNode {
 867 private:
 868   const MemNode::MemOrd _mem_ord;
 869 public:
 870   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) {}
 871   MemNode::MemOrd order() const {
 872     return _mem_ord;
 873   }
 874   virtual uint size_of() const { return sizeof(*this); }
 875 };
 876 
 877 class CompareAndExchangeNode : public LoadStoreNode {
 878 private:
 879   const MemNode::MemOrd _mem_ord;
 880 public:
 881   enum {
 882     ExpectedIn = MemNode::ValueIn+1 // One more input than MemNode
 883   };
 884   CompareAndExchangeNode( Node *c, Node *mem, Node *adr, Node *val, Node *ex, MemNode::MemOrd mem_ord, const TypePtr* at, const Type* t) :
 885     LoadStoreNode(c, mem, adr, val, at, t, 5), _mem_ord(mem_ord) {
 886      init_req(ExpectedIn, ex );
 887   }
 888 
 889   MemNode::MemOrd order() const {
 890     return _mem_ord;
 891   }
 892   virtual uint size_of() const { return sizeof(*this); }
 893 };
 894 
 895 //------------------------------CompareAndSwapBNode---------------------------
 896 class CompareAndSwapBNode : public CompareAndSwapNode {
 897 public:
 898   CompareAndSwapBNode( Node *c, Node *mem, Node *adr, Node *val, Node *ex, MemNode::MemOrd mem_ord) : CompareAndSwapNode(c, mem, adr, val, ex, mem_ord) { }
 899   virtual int Opcode() const;
 900 };
 901 
 902 //------------------------------CompareAndSwapSNode---------------------------
 903 class CompareAndSwapSNode : public CompareAndSwapNode {
 904 public:
 905   CompareAndSwapSNode( Node *c, Node *mem, Node *adr, Node *val, Node *ex, MemNode::MemOrd mem_ord) : CompareAndSwapNode(c, mem, adr, val, ex, mem_ord) { }
 906   virtual int Opcode() const;
 907 };
 908 
 909 //------------------------------CompareAndSwapINode---------------------------
 910 class CompareAndSwapINode : public CompareAndSwapNode {
 911 public:
 912   CompareAndSwapINode( Node *c, Node *mem, Node *adr, Node *val, Node *ex, MemNode::MemOrd mem_ord) : CompareAndSwapNode(c, mem, adr, val, ex, mem_ord) { }
 913   virtual int Opcode() const;
 914 };
 915 
 916 //------------------------------CompareAndSwapLNode---------------------------
 917 class CompareAndSwapLNode : public CompareAndSwapNode {
 918 public:
 919   CompareAndSwapLNode( Node *c, Node *mem, Node *adr, Node *val, Node *ex, MemNode::MemOrd mem_ord) : CompareAndSwapNode(c, mem, adr, val, ex, mem_ord) { }
 920   virtual int Opcode() const;
 921 };
 922 
 923 //------------------------------CompareAndSwapPNode---------------------------
 924 class CompareAndSwapPNode : public CompareAndSwapNode {
 925 public:
 926   CompareAndSwapPNode( Node *c, Node *mem, Node *adr, Node *val, Node *ex, MemNode::MemOrd mem_ord) : CompareAndSwapNode(c, mem, adr, val, ex, mem_ord) { }
 927   virtual int Opcode() const;
 928 };
 929 
 930 //------------------------------CompareAndSwapNNode---------------------------
 931 class CompareAndSwapNNode : public CompareAndSwapNode {
 932 public:
 933   CompareAndSwapNNode( Node *c, Node *mem, Node *adr, Node *val, Node *ex, MemNode::MemOrd mem_ord) : CompareAndSwapNode(c, mem, adr, val, ex, mem_ord) { }
 934   virtual int Opcode() const;
 935 };
 936 
 937 //------------------------------WeakCompareAndSwapBNode---------------------------
 938 class WeakCompareAndSwapBNode : public CompareAndSwapNode {
 939 public:
 940   WeakCompareAndSwapBNode( Node *c, Node *mem, Node *adr, Node *val, Node *ex, MemNode::MemOrd mem_ord) : CompareAndSwapNode(c, mem, adr, val, ex, mem_ord) { }
 941   virtual int Opcode() const;
 942 };
 943 
 944 //------------------------------WeakCompareAndSwapSNode---------------------------
 945 class WeakCompareAndSwapSNode : public CompareAndSwapNode {
 946 public:
 947   WeakCompareAndSwapSNode( Node *c, Node *mem, Node *adr, Node *val, Node *ex, MemNode::MemOrd mem_ord) : CompareAndSwapNode(c, mem, adr, val, ex, mem_ord) { }
 948   virtual int Opcode() const;
 949 };
 950 
 951 //------------------------------WeakCompareAndSwapINode---------------------------
 952 class WeakCompareAndSwapINode : public CompareAndSwapNode {
 953 public:
 954   WeakCompareAndSwapINode( Node *c, Node *mem, Node *adr, Node *val, Node *ex, MemNode::MemOrd mem_ord) : CompareAndSwapNode(c, mem, adr, val, ex, mem_ord) { }
 955   virtual int Opcode() const;
 956 };
 957 
 958 //------------------------------WeakCompareAndSwapLNode---------------------------
 959 class WeakCompareAndSwapLNode : public CompareAndSwapNode {
 960 public:
 961   WeakCompareAndSwapLNode( Node *c, Node *mem, Node *adr, Node *val, Node *ex, MemNode::MemOrd mem_ord) : CompareAndSwapNode(c, mem, adr, val, ex, mem_ord) { }
 962   virtual int Opcode() const;
 963 };
 964 
 965 //------------------------------WeakCompareAndSwapPNode---------------------------
 966 class WeakCompareAndSwapPNode : public CompareAndSwapNode {
 967 public:
 968   WeakCompareAndSwapPNode( Node *c, Node *mem, Node *adr, Node *val, Node *ex, MemNode::MemOrd mem_ord) : CompareAndSwapNode(c, mem, adr, val, ex, mem_ord) { }
 969   virtual int Opcode() const;
 970 };
 971 
 972 //------------------------------WeakCompareAndSwapNNode---------------------------
 973 class WeakCompareAndSwapNNode : public CompareAndSwapNode {
 974 public:
 975   WeakCompareAndSwapNNode( Node *c, Node *mem, Node *adr, Node *val, Node *ex, MemNode::MemOrd mem_ord) : CompareAndSwapNode(c, mem, adr, val, ex, mem_ord) { }
 976   virtual int Opcode() const;
 977 };
 978 
 979 //------------------------------CompareAndExchangeBNode---------------------------
 980 class CompareAndExchangeBNode : public CompareAndExchangeNode {
 981 public:
 982   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) { }
 983   virtual int Opcode() const;
 984 };
 985 
 986 
 987 //------------------------------CompareAndExchangeSNode---------------------------
 988 class CompareAndExchangeSNode : public CompareAndExchangeNode {
 989 public:
 990   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) { }
 991   virtual int Opcode() const;
 992 };
 993 
 994 //------------------------------CompareAndExchangeLNode---------------------------
 995 class CompareAndExchangeLNode : public CompareAndExchangeNode {
 996 public:
 997   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) { }
 998   virtual int Opcode() const;
 999 };
1000 
1001 
1002 //------------------------------CompareAndExchangeINode---------------------------
1003 class CompareAndExchangeINode : public CompareAndExchangeNode {
1004 public:
1005   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) { }
1006   virtual int Opcode() const;
1007 };
1008 
1009 
1010 //------------------------------CompareAndExchangePNode---------------------------
1011 class CompareAndExchangePNode : public CompareAndExchangeNode {
1012 public:
1013   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) { }
1014   virtual int Opcode() const;
1015 };
1016 
1017 //------------------------------CompareAndExchangeNNode---------------------------
1018 class CompareAndExchangeNNode : public CompareAndExchangeNode {
1019 public:
1020   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) { }
1021   virtual int Opcode() const;
1022 };
1023 
1024 //------------------------------GetAndAddBNode---------------------------
1025 class GetAndAddBNode : public LoadStoreNode {
1026 public:
1027   GetAndAddBNode( Node *c, Node *mem, Node *adr, Node *val, const TypePtr* at ) : LoadStoreNode(c, mem, adr, val, at, TypeInt::BYTE, 4) { }
1028   virtual int Opcode() const;
1029 };
1030 
1031 //------------------------------GetAndAddSNode---------------------------
1032 class GetAndAddSNode : public LoadStoreNode {
1033 public:
1034   GetAndAddSNode( Node *c, Node *mem, Node *adr, Node *val, const TypePtr* at ) : LoadStoreNode(c, mem, adr, val, at, TypeInt::SHORT, 4) { }
1035   virtual int Opcode() const;
1036 };
1037 
1038 //------------------------------GetAndAddINode---------------------------
1039 class GetAndAddINode : public LoadStoreNode {
1040 public:
1041   GetAndAddINode( Node *c, Node *mem, Node *adr, Node *val, const TypePtr* at ) : LoadStoreNode(c, mem, adr, val, at, TypeInt::INT, 4) { }
1042   virtual int Opcode() const;
1043 };
1044 
1045 //------------------------------GetAndAddLNode---------------------------
1046 class GetAndAddLNode : public LoadStoreNode {
1047 public:
1048   GetAndAddLNode( Node *c, Node *mem, Node *adr, Node *val, const TypePtr* at ) : LoadStoreNode(c, mem, adr, val, at, TypeLong::LONG, 4) { }
1049   virtual int Opcode() const;
1050 };
1051 
1052 //------------------------------GetAndSetBNode---------------------------
1053 class GetAndSetBNode : public LoadStoreNode {
1054 public:
1055   GetAndSetBNode( Node *c, Node *mem, Node *adr, Node *val, const TypePtr* at ) : LoadStoreNode(c, mem, adr, val, at, TypeInt::BYTE, 4) { }
1056   virtual int Opcode() const;
1057 };
1058 
1059 //------------------------------GetAndSetSNode---------------------------
1060 class GetAndSetSNode : public LoadStoreNode {
1061 public:
1062   GetAndSetSNode( Node *c, Node *mem, Node *adr, Node *val, const TypePtr* at ) : LoadStoreNode(c, mem, adr, val, at, TypeInt::SHORT, 4) { }
1063   virtual int Opcode() const;
1064 };
1065 
1066 //------------------------------GetAndSetINode---------------------------
1067 class GetAndSetINode : public LoadStoreNode {
1068 public:
1069   GetAndSetINode( Node *c, Node *mem, Node *adr, Node *val, const TypePtr* at ) : LoadStoreNode(c, mem, adr, val, at, TypeInt::INT, 4) { }
1070   virtual int Opcode() const;
1071 };
1072 
1073 //------------------------------GetAndSetLNode---------------------------
1074 class GetAndSetLNode : public LoadStoreNode {
1075 public:
1076   GetAndSetLNode( Node *c, Node *mem, Node *adr, Node *val, const TypePtr* at ) : LoadStoreNode(c, mem, adr, val, at, TypeLong::LONG, 4) { }
1077   virtual int Opcode() const;
1078 };
1079 
1080 //------------------------------GetAndSetPNode---------------------------
1081 class GetAndSetPNode : public LoadStoreNode {
1082 public:
1083   GetAndSetPNode( Node *c, Node *mem, Node *adr, Node *val, const TypePtr* at, const Type* t ) : LoadStoreNode(c, mem, adr, val, at, t, 4) { }
1084   virtual int Opcode() const;
1085 };
1086 
1087 //------------------------------GetAndSetNNode---------------------------
1088 class GetAndSetNNode : public LoadStoreNode {
1089 public:
1090   GetAndSetNNode( Node *c, Node *mem, Node *adr, Node *val, const TypePtr* at, const Type* t ) : LoadStoreNode(c, mem, adr, val, at, t, 4) { }
1091   virtual int Opcode() const;
1092 };
1093 
1094 //------------------------------ClearArray-------------------------------------
1095 class ClearArrayNode: public Node {
1096 private:
1097   bool _is_large;
1098   bool _word_copy_only;
1099 public:
1100   ClearArrayNode( Node *ctrl, Node *arymem, Node *word_cnt, Node *base, Node* val, bool is_large)
1101     : Node(ctrl, arymem, word_cnt, base, val), _is_large(is_large),
1102       _word_copy_only(val->bottom_type()->isa_long() && (!val->bottom_type()->is_long()->is_con() || val->bottom_type()->is_long()->get_con() != 0)) {
1103     init_class_id(Class_ClearArray);
1104   }
1105   virtual int         Opcode() const;
1106   virtual const Type *bottom_type() const { return Type::MEMORY; }
1107   // ClearArray modifies array elements, and so affects only the
1108   // array memory addressed by the bottom_type of its base address.
1109   virtual const class TypePtr *adr_type() const;
1110   virtual Node* Identity(PhaseGVN* phase);
1111   virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
1112   virtual uint match_edge(uint idx) const;
1113   bool is_large() const { return _is_large; }
1114   bool word_copy_only() const { return _word_copy_only; }
1115   virtual uint size_of() const { return sizeof(ClearArrayNode); }
1116   virtual uint hash() const { return Node::hash() + _is_large; }
1117   virtual bool cmp(const Node& n) const {
1118     return Node::cmp(n) && _is_large == ((ClearArrayNode&)n).is_large();
1119   }
1120 
1121   // Clear the given area of an object or array.
1122   // The start offset must always be aligned mod BytesPerInt.
1123   // The end offset must always be aligned mod BytesPerLong.
1124   // Return the new memory.
1125   static Node* clear_memory(Node* control, Node* mem, Node* dest,
1126                             Node* val,
1127                             Node* raw_val,
1128                             intptr_t start_offset,
1129                             intptr_t end_offset,
1130                             PhaseGVN* phase);
1131   static Node* clear_memory(Node* control, Node* mem, Node* dest,
1132                             Node* val,
1133                             Node* raw_val,
1134                             intptr_t start_offset,
1135                             Node* end_offset,
1136                             PhaseGVN* phase);
1137   static Node* clear_memory(Node* control, Node* mem, Node* dest,
1138                             Node* raw_val,
1139                             Node* start_offset,
1140                             Node* end_offset,
1141                             PhaseGVN* phase);
1142   // Return allocation input memory edge if it is different instance
1143   // or itself if it is the one we are looking for.
1144   static bool step_through(Node** np, uint instance_id, PhaseValues* phase);
1145 };
1146 
1147 //------------------------------MemBar-----------------------------------------
1148 // There are different flavors of Memory Barriers to match the Java Memory
1149 // Model.  Monitor-enter and volatile-load act as Acquires: no following ref
1150 // can be moved to before them.  We insert a MemBar-Acquire after a FastLock or
1151 // volatile-load.  Monitor-exit and volatile-store act as Release: no
1152 // preceding ref can be moved to after them.  We insert a MemBar-Release
1153 // before a FastUnlock or volatile-store.  All volatiles need to be
1154 // serialized, so we follow all volatile-stores with a MemBar-Volatile to
1155 // separate it from any following volatile-load.
1156 class MemBarNode: public MultiNode {
1157   virtual uint hash() const ;                  // { return NO_HASH; }
1158   virtual bool cmp( const Node &n ) const ;    // Always fail, except on self
1159 
1160   virtual uint size_of() const { return sizeof(*this); }
1161   // Memory type this node is serializing.  Usually either rawptr or bottom.
1162   const TypePtr* _adr_type;
1163 
1164   // How is this membar related to a nearby memory access?
1165   enum {
1166     Standalone,
1167     TrailingLoad,
1168     TrailingStore,
1169     LeadingStore,
1170     TrailingLoadStore,
1171     LeadingLoadStore,
1172     TrailingExpandedArrayCopy
1173   } _kind;
1174 
1175 #ifdef ASSERT
1176   uint _pair_idx;
1177 #endif
1178 
1179 public:
1180   enum {
1181     Precedent = TypeFunc::Parms  // optional edge to force precedence
1182   };
1183   MemBarNode(Compile* C, int alias_idx, Node* precedent);
1184   virtual int Opcode() const = 0;
1185   virtual const class TypePtr *adr_type() const { return _adr_type; }
1186   virtual const Type* Value(PhaseGVN* phase) const;
1187   virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
1188   virtual uint match_edge(uint idx) const { return 0; }
1189   virtual const Type *bottom_type() const { return TypeTuple::MEMBAR; }
1190   virtual Node *match(const ProjNode *proj, const Matcher *m, const RegMask* mask);
1191   // Factory method.  Builds a wide or narrow membar.
1192   // Optional 'precedent' becomes an extra edge if not null.
1193   static MemBarNode* make(Compile* C, int opcode,
1194                           int alias_idx = Compile::AliasIdxBot,
1195                           Node* precedent = nullptr);
1196 
1197   MemBarNode* trailing_membar() const;
1198   MemBarNode* leading_membar() const;
1199 
1200   void set_trailing_load() { _kind = TrailingLoad; }
1201   bool trailing_load() const { return _kind == TrailingLoad; }
1202   bool trailing_store() const { return _kind == TrailingStore; }
1203   bool leading_store() const { return _kind == LeadingStore; }
1204   bool trailing_load_store() const { return _kind == TrailingLoadStore; }
1205   bool leading_load_store() const { return _kind == LeadingLoadStore; }
1206   bool trailing() const { return _kind == TrailingLoad || _kind == TrailingStore || _kind == TrailingLoadStore; }
1207   bool leading() const { return _kind == LeadingStore || _kind == LeadingLoadStore; }
1208   bool standalone() const { return _kind == Standalone; }
1209   void set_trailing_expanded_array_copy() { _kind = TrailingExpandedArrayCopy; }
1210   bool trailing_expanded_array_copy() const { return _kind == TrailingExpandedArrayCopy; }
1211 
1212   static void set_store_pair(MemBarNode* leading, MemBarNode* trailing);
1213   static void set_load_store_pair(MemBarNode* leading, MemBarNode* trailing);
1214 
1215   void remove(PhaseIterGVN *igvn);
1216 };
1217 
1218 // "Acquire" - no following ref can move before (but earlier refs can
1219 // follow, like an early Load stalled in cache).  Requires multi-cpu
1220 // visibility.  Inserted after a volatile load.
1221 class MemBarAcquireNode: public MemBarNode {
1222 public:
1223   MemBarAcquireNode(Compile* C, int alias_idx, Node* precedent)
1224     : MemBarNode(C, alias_idx, precedent) {}
1225   virtual int Opcode() const;
1226 };
1227 
1228 // "Acquire" - no following ref can move before (but earlier refs can
1229 // follow, like an early Load stalled in cache).  Requires multi-cpu
1230 // visibility.  Inserted independent of any load, as required
1231 // for intrinsic Unsafe.loadFence().
1232 class LoadFenceNode: public MemBarNode {
1233 public:
1234   LoadFenceNode(Compile* C, int alias_idx, Node* precedent)
1235     : MemBarNode(C, alias_idx, precedent) {}
1236   virtual int Opcode() const;
1237 };
1238 
1239 // "Release" - no earlier ref can move after (but later refs can move
1240 // up, like a speculative pipelined cache-hitting Load).  Requires
1241 // multi-cpu visibility.  Inserted before a volatile store.
1242 class MemBarReleaseNode: public MemBarNode {
1243 public:
1244   MemBarReleaseNode(Compile* C, int alias_idx, Node* precedent)
1245     : MemBarNode(C, alias_idx, precedent) {}
1246   virtual int Opcode() const;
1247 };
1248 
1249 // "Release" - no earlier ref can move after (but later refs can move
1250 // up, like a speculative pipelined cache-hitting Load).  Requires
1251 // multi-cpu visibility.  Inserted independent of any store, as required
1252 // for intrinsic Unsafe.storeFence().
1253 class StoreFenceNode: public MemBarNode {
1254 public:
1255   StoreFenceNode(Compile* C, int alias_idx, Node* precedent)
1256     : MemBarNode(C, alias_idx, precedent) {}
1257   virtual int Opcode() const;
1258 };
1259 
1260 // "Acquire" - no following ref can move before (but earlier refs can
1261 // follow, like an early Load stalled in cache).  Requires multi-cpu
1262 // visibility.  Inserted after a FastLock.
1263 class MemBarAcquireLockNode: public MemBarNode {
1264 public:
1265   MemBarAcquireLockNode(Compile* C, int alias_idx, Node* precedent)
1266     : MemBarNode(C, alias_idx, precedent) {}
1267   virtual int Opcode() const;
1268 };
1269 
1270 // "Release" - no earlier ref can move after (but later refs can move
1271 // up, like a speculative pipelined cache-hitting Load).  Requires
1272 // multi-cpu visibility.  Inserted before a FastUnLock.
1273 class MemBarReleaseLockNode: public MemBarNode {
1274 public:
1275   MemBarReleaseLockNode(Compile* C, int alias_idx, Node* precedent)
1276     : MemBarNode(C, alias_idx, precedent) {}
1277   virtual int Opcode() const;
1278 };
1279 
1280 class MemBarStoreStoreNode: public MemBarNode {
1281 public:
1282   MemBarStoreStoreNode(Compile* C, int alias_idx, Node* precedent)
1283     : MemBarNode(C, alias_idx, precedent) {
1284     init_class_id(Class_MemBarStoreStore);
1285   }
1286   virtual int Opcode() const;
1287 };
1288 
1289 class StoreStoreFenceNode: public MemBarNode {
1290 public:
1291   StoreStoreFenceNode(Compile* C, int alias_idx, Node* precedent)
1292     : MemBarNode(C, alias_idx, precedent) {}
1293   virtual int Opcode() const;
1294 };
1295 
1296 // Ordering between a volatile store and a following volatile load.
1297 // Requires multi-CPU visibility?
1298 class MemBarVolatileNode: public MemBarNode {
1299 public:
1300   MemBarVolatileNode(Compile* C, int alias_idx, Node* precedent)
1301     : MemBarNode(C, alias_idx, precedent) {}
1302   virtual int Opcode() const;
1303 };
1304 
1305 // Ordering within the same CPU.  Used to order unsafe memory references
1306 // inside the compiler when we lack alias info.  Not needed "outside" the
1307 // compiler because the CPU does all the ordering for us.
1308 class MemBarCPUOrderNode: public MemBarNode {
1309 public:
1310   MemBarCPUOrderNode(Compile* C, int alias_idx, Node* precedent)
1311     : MemBarNode(C, alias_idx, precedent) {}
1312   virtual int Opcode() const;
1313   virtual uint ideal_reg() const { return 0; } // not matched in the AD file
1314 };
1315 
1316 class OnSpinWaitNode: public MemBarNode {
1317 public:
1318   OnSpinWaitNode(Compile* C, int alias_idx, Node* precedent)
1319     : MemBarNode(C, alias_idx, precedent) {}
1320   virtual int Opcode() const;
1321 };
1322 
1323 // Isolation of object setup after an AllocateNode and before next safepoint.
1324 // (See comment in memnode.cpp near InitializeNode::InitializeNode for semantics.)
1325 class InitializeNode: public MemBarNode {
1326   friend class AllocateNode;
1327 
1328   enum {
1329     Incomplete    = 0,
1330     Complete      = 1,
1331     WithArraycopy = 2
1332   };
1333   int _is_complete;
1334 
1335   bool _does_not_escape;
1336 
1337 public:
1338   enum {
1339     Control    = TypeFunc::Control,
1340     Memory     = TypeFunc::Memory,     // MergeMem for states affected by this op
1341     RawAddress = TypeFunc::Parms+0,    // the newly-allocated raw address
1342     RawStores  = TypeFunc::Parms+1     // zero or more stores (or TOP)
1343   };
1344 
1345   InitializeNode(Compile* C, int adr_type, Node* rawoop);
1346   virtual int Opcode() const;
1347   virtual uint size_of() const { return sizeof(*this); }
1348   virtual uint ideal_reg() const { return 0; } // not matched in the AD file
1349   virtual const RegMask &in_RegMask(uint) const;  // mask for RawAddress
1350 
1351   // Manage incoming memory edges via a MergeMem on in(Memory):
1352   Node* memory(uint alias_idx);
1353 
1354   // The raw memory edge coming directly from the Allocation.
1355   // The contents of this memory are *always* all-zero-bits.
1356   Node* zero_memory() { return memory(Compile::AliasIdxRaw); }
1357 
1358   // Return the corresponding allocation for this initialization (or null if none).
1359   // (Note: Both InitializeNode::allocation and AllocateNode::initialization
1360   // are defined in graphKit.cpp, which sets up the bidirectional relation.)
1361   AllocateNode* allocation();
1362 
1363   // Anything other than zeroing in this init?
1364   bool is_non_zero();
1365 
1366   // An InitializeNode must completed before macro expansion is done.
1367   // Completion requires that the AllocateNode must be followed by
1368   // initialization of the new memory to zero, then to any initializers.
1369   bool is_complete() { return _is_complete != Incomplete; }
1370   bool is_complete_with_arraycopy() { return (_is_complete & WithArraycopy) != 0; }
1371 
1372   // Mark complete.  (Must not yet be complete.)
1373   void set_complete(PhaseGVN* phase);
1374   void set_complete_with_arraycopy() { _is_complete = Complete | WithArraycopy; }
1375 
1376   bool does_not_escape() { return _does_not_escape; }
1377   void set_does_not_escape() { _does_not_escape = true; }
1378 
1379 #ifdef ASSERT
1380   // ensure all non-degenerate stores are ordered and non-overlapping
1381   bool stores_are_sane(PhaseValues* phase);
1382 #endif //ASSERT
1383 
1384   // See if this store can be captured; return offset where it initializes.
1385   // Return 0 if the store cannot be moved (any sort of problem).
1386   intptr_t can_capture_store(StoreNode* st, PhaseGVN* phase, bool can_reshape);
1387 
1388   // Capture another store; reformat it to write my internal raw memory.
1389   // Return the captured copy, else null if there is some sort of problem.
1390   Node* capture_store(StoreNode* st, intptr_t start, PhaseGVN* phase, bool can_reshape);
1391 
1392   // Find captured store which corresponds to the range [start..start+size).
1393   // Return my own memory projection (meaning the initial zero bits)
1394   // if there is no such store.  Return null if there is a problem.
1395   Node* find_captured_store(intptr_t start, int size_in_bytes, PhaseValues* phase);
1396 
1397   // Called when the associated AllocateNode is expanded into CFG.
1398   Node* complete_stores(Node* rawctl, Node* rawmem, Node* rawptr,
1399                         intptr_t header_size, Node* size_in_bytes,
1400                         PhaseIterGVN* phase);
1401 
1402   // An Initialize node has multiple memory projections. Helper methods used when the node is removed.
1403   // For use at parse time
1404   void replace_mem_projs_by(Node* mem, Compile* C);
1405   // For use with IGVN
1406   void replace_mem_projs_by(Node* mem, PhaseIterGVN* igvn);
1407 
1408   // Does a NarrowMemProj with this adr_type and this node as input already exist?
1409   bool already_has_narrow_mem_proj_with_adr_type(const TypePtr* adr_type) const;
1410 
1411   // Used during matching: find the MachProj memory projection if there's one. Expectation is that there should be at
1412   // most one.
1413   MachProjNode* mem_mach_proj() const;
1414 
1415 private:
1416   void remove_extra_zeroes();
1417 
1418   // Find out where a captured store should be placed (or already is placed).
1419   int captured_store_insertion_point(intptr_t start, int size_in_bytes,
1420                                      PhaseValues* phase);
1421 
1422   static intptr_t get_store_offset(Node* st, PhaseValues* phase);
1423 
1424   Node* make_raw_address(intptr_t offset, PhaseGVN* phase);
1425 
1426   bool detect_init_independence(Node* value, PhaseGVN* phase);
1427 
1428   void coalesce_subword_stores(intptr_t header_size, Node* size_in_bytes,
1429                                PhaseGVN* phase);
1430 
1431   intptr_t find_next_fullword_store(uint i, PhaseGVN* phase);
1432 
1433   // Iterate with i over all NarrowMemProj uses calling callback
1434   template <class Callback, class Iterator> NarrowMemProjNode* apply_to_narrow_mem_projs_any_iterator(Iterator i, Callback callback) const {
1435     auto filter = [&](ProjNode* proj) {
1436       if (proj->is_NarrowMemProj() && callback(proj->as_NarrowMemProj()) == BREAK_AND_RETURN_CURRENT_PROJ) {
1437         return BREAK_AND_RETURN_CURRENT_PROJ;
1438       }
1439       return CONTINUE;
1440     };
1441     ProjNode* res = apply_to_projs_any_iterator(i, filter);
1442     if (res == nullptr) {
1443       return nullptr;
1444     }
1445     return res->as_NarrowMemProj();
1446   }
1447 
1448 public:
1449 
1450   // callback is allowed to add new uses that will then be iterated over
1451   template <class Callback> void for_each_narrow_mem_proj_with_new_uses(Callback callback) const {
1452     auto callback_always_continue = [&](NarrowMemProjNode* proj) {
1453       callback(proj);
1454       return MultiNode::CONTINUE;
1455     };
1456     DUIterator i = outs();
1457     apply_to_narrow_mem_projs_any_iterator(UsesIterator(i, this), callback_always_continue);
1458   }
1459 };
1460 
1461 //------------------------------MergeMem---------------------------------------
1462 // (See comment in memnode.cpp near MergeMemNode::MergeMemNode for semantics.)
1463 class MergeMemNode: public Node {
1464   virtual uint hash() const ;                  // { return NO_HASH; }
1465   virtual bool cmp( const Node &n ) const ;    // Always fail, except on self
1466   friend class MergeMemStream;
1467   MergeMemNode(Node* def);  // clients use MergeMemNode::make
1468 
1469 public:
1470   // If the input is a whole memory state, clone it with all its slices intact.
1471   // Otherwise, make a new memory state with just that base memory input.
1472   // In either case, the result is a newly created MergeMem.
1473   static MergeMemNode* make(Node* base_memory);
1474 
1475   virtual int Opcode() const;
1476   virtual Node* Identity(PhaseGVN* phase);
1477   virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
1478   virtual uint ideal_reg() const { return NotAMachineReg; }
1479   virtual uint match_edge(uint idx) const { return 0; }
1480   virtual const RegMask &out_RegMask() const;
1481   virtual const Type *bottom_type() const { return Type::MEMORY; }
1482   virtual const TypePtr *adr_type() const { return TypePtr::BOTTOM; }
1483   // sparse accessors
1484   // Fetch the previously stored "set_memory_at", or else the base memory.
1485   // (Caller should clone it if it is a phi-nest.)
1486   Node* memory_at(uint alias_idx) const;
1487   // set the memory, regardless of its previous value
1488   void set_memory_at(uint alias_idx, Node* n);
1489   // the "base" is the memory that provides the non-finite support
1490   Node* base_memory() const       { return in(Compile::AliasIdxBot); }
1491   // warning: setting the base can implicitly set any of the other slices too
1492   void set_base_memory(Node* def);
1493   // sentinel value which denotes a copy of the base memory:
1494   Node*   empty_memory() const    { return in(Compile::AliasIdxTop); }
1495   static Node* make_empty_memory(); // where the sentinel comes from
1496   bool is_empty_memory(Node* n) const { assert((n == empty_memory()) == n->is_top(), "sanity"); return n->is_top(); }
1497   // hook for the iterator, to perform any necessary setup
1498   void iteration_setup(const MergeMemNode* other = nullptr);
1499   // push sentinels until I am at least as long as the other (semantic no-op)
1500   void grow_to_match(const MergeMemNode* other);
1501   bool verify_sparse() const PRODUCT_RETURN0;
1502 #ifndef PRODUCT
1503   virtual void dump_spec(outputStream *st) const;
1504 #endif
1505 };
1506 
1507 class MergeMemStream : public StackObj {
1508  private:
1509   MergeMemNode*       _mm;
1510   const MergeMemNode* _mm2;  // optional second guy, contributes non-empty iterations
1511   Node*               _mm_base;  // loop-invariant base memory of _mm
1512   int                 _idx;
1513   int                 _cnt;
1514   Node*               _mem;
1515   Node*               _mem2;
1516   int                 _cnt2;
1517 
1518   void init(MergeMemNode* mm, const MergeMemNode* mm2 = nullptr) {
1519     // subsume_node will break sparseness at times, whenever a memory slice
1520     // folds down to a copy of the base ("fat") memory.  In such a case,
1521     // the raw edge will update to base, although it should be top.
1522     // This iterator will recognize either top or base_memory as an
1523     // "empty" slice.  See is_empty, is_empty2, and next below.
1524     //
1525     // The sparseness property is repaired in MergeMemNode::Ideal.
1526     // As long as access to a MergeMem goes through this iterator
1527     // or the memory_at accessor, flaws in the sparseness will
1528     // never be observed.
1529     //
1530     // Also, iteration_setup repairs sparseness.
1531     assert(mm->verify_sparse(), "please, no dups of base");
1532     assert(mm2==nullptr || mm2->verify_sparse(), "please, no dups of base");
1533 
1534     _mm  = mm;
1535     _mm_base = mm->base_memory();
1536     _mm2 = mm2;
1537     _cnt = mm->req();
1538     _idx = Compile::AliasIdxBot-1; // start at the base memory
1539     _mem = nullptr;
1540     _mem2 = nullptr;
1541   }
1542 
1543 #ifdef ASSERT
1544   Node* check_memory() const {
1545     if (at_base_memory())
1546       return _mm->base_memory();
1547     else if ((uint)_idx < _mm->req() && !_mm->in(_idx)->is_top())
1548       return _mm->memory_at(_idx);
1549     else
1550       return _mm_base;
1551   }
1552   Node* check_memory2() const {
1553     return at_base_memory()? _mm2->base_memory(): _mm2->memory_at(_idx);
1554   }
1555 #endif
1556 
1557   static bool match_memory(Node* mem, const MergeMemNode* mm, int idx) PRODUCT_RETURN0;
1558   void assert_synch() const {
1559     assert(!_mem || _idx >= _cnt || match_memory(_mem, _mm, _idx),
1560            "no side-effects except through the stream");
1561   }
1562 
1563  public:
1564 
1565   // expected usages:
1566   // for (MergeMemStream mms(mem->is_MergeMem()); next_non_empty(); ) { ... }
1567   // for (MergeMemStream mms(mem1, mem2); next_non_empty2(); ) { ... }
1568 
1569   // iterate over one merge
1570   MergeMemStream(MergeMemNode* mm) {
1571     mm->iteration_setup();
1572     init(mm);
1573     DEBUG_ONLY(_cnt2 = 999);
1574   }
1575   // iterate in parallel over two merges
1576   // only iterates through non-empty elements of mm2
1577   MergeMemStream(MergeMemNode* mm, const MergeMemNode* mm2) {
1578     assert(mm2, "second argument must be a MergeMem also");
1579     ((MergeMemNode*)mm2)->iteration_setup();  // update hidden state
1580     mm->iteration_setup(mm2);
1581     init(mm, mm2);
1582     _cnt2 = mm2->req();
1583   }
1584 #ifdef ASSERT
1585   ~MergeMemStream() {
1586     assert_synch();
1587   }
1588 #endif
1589 
1590   MergeMemNode* all_memory() const {
1591     return _mm;
1592   }
1593   Node* base_memory() const {
1594     assert(_mm_base == _mm->base_memory(), "no update to base memory, please");
1595     return _mm_base;
1596   }
1597   const MergeMemNode* all_memory2() const {
1598     assert(_mm2 != nullptr, "");
1599     return _mm2;
1600   }
1601   bool at_base_memory() const {
1602     return _idx == Compile::AliasIdxBot;
1603   }
1604   int alias_idx() const {
1605     assert(_mem, "must call next 1st");
1606     return _idx;
1607   }
1608 
1609   const TypePtr* adr_type() const {
1610     return Compile::current()->get_adr_type(alias_idx());
1611   }
1612 
1613   const TypePtr* adr_type(Compile* C) const {
1614     return C->get_adr_type(alias_idx());
1615   }
1616   bool is_empty() const {
1617     assert(_mem, "must call next 1st");
1618     assert(_mem->is_top() == (_mem==_mm->empty_memory()), "correct sentinel");
1619     return _mem->is_top();
1620   }
1621   bool is_empty2() const {
1622     assert(_mem2, "must call next 1st");
1623     assert(_mem2->is_top() == (_mem2==_mm2->empty_memory()), "correct sentinel");
1624     return _mem2->is_top();
1625   }
1626   Node* memory() const {
1627     assert(!is_empty(), "must not be empty");
1628     assert_synch();
1629     return _mem;
1630   }
1631   // get the current memory, regardless of empty or non-empty status
1632   Node* force_memory() const {
1633     assert(!is_empty() || !at_base_memory(), "");
1634     // Use _mm_base to defend against updates to _mem->base_memory().
1635     Node *mem = _mem->is_top() ? _mm_base : _mem;
1636     assert(mem == check_memory(), "");
1637     return mem;
1638   }
1639   Node* memory2() const {
1640     assert(_mem2 == check_memory2(), "");
1641     return _mem2;
1642   }
1643   void set_memory(Node* mem) {
1644     if (at_base_memory()) {
1645       // Note that this does not change the invariant _mm_base.
1646       _mm->set_base_memory(mem);
1647     } else {
1648       _mm->set_memory_at(_idx, mem);
1649     }
1650     _mem = mem;
1651     assert_synch();
1652   }
1653 
1654   // Recover from a side effect to the MergeMemNode.
1655   void set_memory() {
1656     _mem = _mm->in(_idx);
1657   }
1658 
1659   bool next()  { return next(false); }
1660   bool next2() { return next(true); }
1661 
1662   bool next_non_empty()  { return next_non_empty(false); }
1663   bool next_non_empty2() { return next_non_empty(true); }
1664   // next_non_empty2 can yield states where is_empty() is true
1665 
1666  private:
1667   // find the next item, which might be empty
1668   bool next(bool have_mm2) {
1669     assert((_mm2 != nullptr) == have_mm2, "use other next");
1670     assert_synch();
1671     if (++_idx < _cnt) {
1672       // Note:  This iterator allows _mm to be non-sparse.
1673       // It behaves the same whether _mem is top or base_memory.
1674       _mem = _mm->in(_idx);
1675       if (have_mm2)
1676         _mem2 = _mm2->in((_idx < _cnt2) ? _idx : Compile::AliasIdxTop);
1677       return true;
1678     }
1679     return false;
1680   }
1681 
1682   // find the next non-empty item
1683   bool next_non_empty(bool have_mm2) {
1684     while (next(have_mm2)) {
1685       if (!is_empty()) {
1686         // make sure _mem2 is filled in sensibly
1687         if (have_mm2 && _mem2->is_top())  _mem2 = _mm2->base_memory();
1688         return true;
1689       } else if (have_mm2 && !is_empty2()) {
1690         return true;   // is_empty() == true
1691       }
1692     }
1693     return false;
1694   }
1695 };
1696 
1697 // cachewb node for guaranteeing writeback of the cache line at a
1698 // given address to (non-volatile) RAM
1699 class CacheWBNode : public Node {
1700 public:
1701   CacheWBNode(Node *ctrl, Node *mem, Node *addr) : Node(ctrl, mem, addr) {}
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 TypePtr *adr_type() const { return TypePtr::BOTTOM; }
1706   virtual const Type *bottom_type() const { return Type::MEMORY; }
1707 };
1708 
1709 // cachewb pre sync node for ensuring that writebacks are serialised
1710 // relative to preceding or following stores
1711 class CacheWBPreSyncNode : public Node {
1712 public:
1713   CacheWBPreSyncNode(Node *ctrl, Node *mem) : Node(ctrl, mem) {}
1714   virtual int Opcode() const;
1715   virtual uint ideal_reg() const { return NotAMachineReg; }
1716   virtual uint match_edge(uint idx) const { return false; }
1717   virtual const TypePtr *adr_type() const { return TypePtr::BOTTOM; }
1718   virtual const Type *bottom_type() const { return Type::MEMORY; }
1719 };
1720 
1721 // cachewb pre sync node for ensuring that writebacks are serialised
1722 // relative to preceding or following stores
1723 class CacheWBPostSyncNode : public Node {
1724 public:
1725   CacheWBPostSyncNode(Node *ctrl, Node *mem) : Node(ctrl, mem) {}
1726   virtual int Opcode() const;
1727   virtual uint ideal_reg() const { return NotAMachineReg; }
1728   virtual uint match_edge(uint idx) const { return false; }
1729   virtual const TypePtr *adr_type() const { return TypePtr::BOTTOM; }
1730   virtual const Type *bottom_type() const { return Type::MEMORY; }
1731 };
1732 
1733 //------------------------------Prefetch---------------------------------------
1734 
1735 // Allocation prefetch which may fault, TLAB size have to be adjusted.
1736 class PrefetchAllocationNode : public Node {
1737 public:
1738   PrefetchAllocationNode(Node *mem, Node *adr) : Node(nullptr,mem,adr) {}
1739   virtual int Opcode() const;
1740   virtual uint ideal_reg() const { return NotAMachineReg; }
1741   virtual uint match_edge(uint idx) const { return idx==2; }
1742   virtual const Type *bottom_type() const { return ( AllocatePrefetchStyle == 3 ) ? Type::MEMORY : Type::ABIO; }
1743 };
1744 
1745 #endif // SHARE_OPTO_MEMNODE_HPP