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.
   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).
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  18  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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  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
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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          OopStore               // Preceding oop store, only in StoreCM
  60   };
  61   typedef enum { unordered = 0,
  62                  acquire,       // Load has to acquire or be succeeded by MemBarAcquire.
  63                  release,       // Store has to release or be preceded by MemBarRelease.
  64                  seqcst,        // LoadStore has to have both acquire and release semantics.
  65                  unset          // The memory ordering is not set (used for testing)
  66   } MemOrd;
  67 protected:
  68   MemNode( Node *c0, Node *c1, Node *c2, const TypePtr* at ) :
  69       Node(c0,c1,c2),
  70       _unaligned_access(false),
  71       _mismatched_access(false),
  72       _unsafe_access(false),
  73       _barrier_data(0) {
  74     init_class_id(Class_Mem);
  75     debug_only(_adr_type=at; adr_type();)
  76   }
  77   MemNode( Node *c0, Node *c1, Node *c2, const TypePtr* at, Node *c3 ) :
  78       Node(c0,c1,c2,c3),
  79       _unaligned_access(false),
  80       _mismatched_access(false),
  81       _unsafe_access(false),
  82       _barrier_data(0) {
  83     init_class_id(Class_Mem);
  84     debug_only(_adr_type=at; adr_type();)
  85   }
  86   MemNode( Node *c0, Node *c1, Node *c2, const TypePtr* at, Node *c3, Node *c4) :
  87       Node(c0,c1,c2,c3,c4),
  88       _unaligned_access(false),
  89       _mismatched_access(false),
  90       _unsafe_access(false),
  91       _barrier_data(0) {
  92     init_class_id(Class_Mem);
  93     debug_only(_adr_type=at; adr_type();)
  94   }
  95 
  96   virtual Node* find_previous_arraycopy(PhaseValues* phase, Node* ld_alloc, Node*& mem, bool can_see_stored_value) const { return nullptr; }
  97   ArrayCopyNode* find_array_copy_clone(Node* ld_alloc, Node* mem) const;
  98   static bool check_if_adr_maybe_raw(Node* adr);
  99 
 100 public:
 101   // Helpers for the optimizer.  Documented in memnode.cpp.
 102   static bool detect_ptr_independence(Node* p1, AllocateNode* a1,
 103                                       Node* p2, AllocateNode* a2,
 104                                       PhaseTransform* phase);
 105   static bool adr_phi_is_loop_invariant(Node* adr_phi, Node* cast);
 106 
 107   static Node *optimize_simple_memory_chain(Node *mchain, const TypeOopPtr *t_oop, Node *load, PhaseGVN *phase);
 108   static Node *optimize_memory_chain(Node *mchain, const TypePtr *t_adr, Node *load, PhaseGVN *phase);
 109   // The following two should probably be phase-specific functions:
 110   static DomResult maybe_all_controls_dominate(Node* dom, Node* sub);
 111   static bool all_controls_dominate(Node* dom, Node* sub) {
 112     DomResult dom_result = maybe_all_controls_dominate(dom, sub);
 113     return dom_result == DomResult::Dominate;
 114   }
 115 
 116   virtual const class TypePtr *adr_type() const;  // returns bottom_type of address
 117 
 118   // Shared code for Ideal methods:
 119   Node *Ideal_common(PhaseGVN *phase, bool can_reshape);  // Return -1 for short-circuit null.
 120 
 121   // Helper function for adr_type() implementations.
 122   static const TypePtr* calculate_adr_type(const Type* t, const TypePtr* cross_check = nullptr);
 123 
 124   // Raw access function, to allow copying of adr_type efficiently in
 125   // product builds and retain the debug info for debug builds.
 126   const TypePtr *raw_adr_type() const {
 127     return DEBUG_ONLY(_adr_type) NOT_DEBUG(nullptr);
 128   }
 129 
 130   // Return the barrier data of n, if available, or 0 otherwise.
 131   static uint8_t barrier_data(const Node* n);
 132 
 133   // Map a load or store opcode to its corresponding store opcode.
 134   // (Return -1 if unknown.)
 135   virtual int store_Opcode() const { return -1; }
 136 
 137   // What is the type of the value in memory?  (T_VOID mean "unspecified".)
 138   virtual BasicType memory_type() const = 0;
 139   virtual int memory_size() const {
 140 #ifdef ASSERT
 141     return type2aelembytes(memory_type(), true);
 142 #else
 143     return type2aelembytes(memory_type());
 144 #endif
 145   }
 146 
 147   uint8_t barrier_data() { return _barrier_data; }
 148   void set_barrier_data(uint8_t barrier_data) { _barrier_data = barrier_data; }
 149 
 150   // Search through memory states which precede this node (load or store).
 151   // Look for an exact match for the address, with no intervening
 152   // aliased stores.
 153   Node* find_previous_store(PhaseValues* phase);
 154 
 155   // Can this node (load or store) accurately see a stored value in
 156   // the given memory state?  (The state may or may not be in(Memory).)
 157   Node* can_see_stored_value(Node* st, PhaseValues* phase) const;
 158 
 159   void set_unaligned_access() { _unaligned_access = true; }
 160   bool is_unaligned_access() const { return _unaligned_access; }
 161   void set_mismatched_access() { _mismatched_access = true; }
 162   bool is_mismatched_access() const { return _mismatched_access; }
 163   void set_unsafe_access() { _unsafe_access = true; }
 164   bool is_unsafe_access() const { return _unsafe_access; }
 165 
 166 #ifndef PRODUCT
 167   static void dump_adr_type(const Node* mem, const TypePtr* adr_type, outputStream *st);
 168   virtual void dump_spec(outputStream *st) const;
 169 #endif
 170 };
 171 
 172 //------------------------------LoadNode---------------------------------------
 173 // Load value; requires Memory and Address
 174 class LoadNode : public MemNode {
 175 public:
 176   // Some loads (from unsafe) should be pinned: they don't depend only
 177   // on the dominating test.  The field _control_dependency below records
 178   // whether that node depends only on the dominating test.
 179   // Pinned and UnknownControl are similar, but differ in that Pinned
 180   // loads are not allowed to float across safepoints, whereas UnknownControl
 181   // loads are allowed to do that. Therefore, Pinned is stricter.
 182   enum ControlDependency {
 183     Pinned,
 184     UnknownControl,
 185     DependsOnlyOnTest
 186   };
 187 
 188 private:
 189   // LoadNode::hash() doesn't take the _control_dependency field
 190   // into account: If the graph already has a non-pinned LoadNode and
 191   // we add a pinned LoadNode with the same inputs, it's safe for GVN
 192   // to replace the pinned LoadNode with the non-pinned LoadNode,
 193   // otherwise it wouldn't be safe to have a non pinned LoadNode with
 194   // those inputs in the first place. If the graph already has a
 195   // pinned LoadNode and we add a non pinned LoadNode with the same
 196   // inputs, it's safe (but suboptimal) for GVN to replace the
 197   // non-pinned LoadNode by the pinned LoadNode.
 198   ControlDependency _control_dependency;
 199 
 200   // On platforms with weak memory ordering (e.g., PPC, Ia64) we distinguish
 201   // loads that can be reordered, and such requiring acquire semantics to
 202   // adhere to the Java specification.  The required behaviour is stored in
 203   // this field.
 204   const MemOrd _mo;
 205 
 206   AllocateNode* is_new_object_mark_load() const;
 207 
 208 protected:
 209   virtual bool cmp(const Node &n) const;
 210   virtual uint size_of() const; // Size is bigger
 211   // Should LoadNode::Ideal() attempt to remove control edges?
 212   virtual bool can_remove_control() const;
 213   const Type* const _type;      // What kind of value is loaded?
 214 
 215   virtual Node* find_previous_arraycopy(PhaseValues* phase, Node* ld_alloc, Node*& mem, bool can_see_stored_value) const;
 216 public:
 217 
 218   LoadNode(Node *c, Node *mem, Node *adr, const TypePtr* at, const Type *rt, MemOrd mo, ControlDependency control_dependency)
 219     : MemNode(c,mem,adr,at), _control_dependency(control_dependency), _mo(mo), _type(rt) {
 220     init_class_id(Class_Load);
 221   }
 222   inline bool is_unordered() const { return !is_acquire(); }
 223   inline bool is_acquire() const {
 224     assert(_mo == unordered || _mo == acquire, "unexpected");
 225     return _mo == acquire;
 226   }
 227   inline bool is_unsigned() const {
 228     int lop = Opcode();
 229     return (lop == Op_LoadUB) || (lop == Op_LoadUS);
 230   }
 231 
 232   // Polymorphic factory method:
 233   static Node* make(PhaseGVN& gvn, Node* c, Node* mem, Node* adr,
 234                     const TypePtr* at, const Type* rt, BasicType bt,
 235                     MemOrd mo, ControlDependency control_dependency = DependsOnlyOnTest,
 236                     bool require_atomic_access = false, bool unaligned = false, bool mismatched = false, bool unsafe = false,
 237                     uint8_t barrier_data = 0);
 238 
 239   virtual uint hash()   const;  // Check the type
 240 
 241   // Handle algebraic identities here.  If we have an identity, return the Node
 242   // we are equivalent to.  We look for Load of a Store.
 243   virtual Node* Identity(PhaseGVN* phase);
 244 
 245   // If the load is from Field memory and the pointer is non-null, it might be possible to
 246   // zero out the control input.
 247   // If the offset is constant and the base is an object allocation,
 248   // try to hook me up to the exact initializing store.
 249   virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
 250 
 251   // Return true if it's possible to split the Load through a Phi merging the bases
 252   bool can_split_through_phi_base(PhaseGVN *phase);
 253 
 254   // Split instance field load through Phi.
 255   Node* split_through_phi(PhaseGVN *phase, bool ignore_missing_instance_id = false);
 256 
 257   // Recover original value from boxed values
 258   Node *eliminate_autobox(PhaseIterGVN *igvn);
 259 
 260   // Compute a new Type for this node.  Basically we just do the pre-check,
 261   // then call the virtual add() to set the type.
 262   virtual const Type* Value(PhaseGVN* phase) const;
 263 
 264   // Common methods for LoadKlass and LoadNKlass nodes.
 265   const Type* klass_value_common(PhaseGVN* phase) const;
 266   Node* klass_identity_common(PhaseGVN* phase);
 267 
 268   virtual uint ideal_reg() const;
 269   virtual const Type *bottom_type() const;
 270   // Following method is copied from TypeNode:
 271   void set_type(const Type* t) {
 272     assert(t != nullptr, "sanity");
 273     debug_only(uint check_hash = (VerifyHashTableKeys && _hash_lock) ? hash() : NO_HASH);
 274     *(const Type**)&_type = t;   // cast away const-ness
 275     // If this node is in the hash table, make sure it doesn't need a rehash.
 276     assert(check_hash == NO_HASH || check_hash == hash(), "type change must preserve hash code");
 277   }
 278   const Type* type() const { assert(_type != nullptr, "sanity"); return _type; };
 279 
 280   // Do not match memory edge
 281   virtual uint match_edge(uint idx) const;
 282 
 283   // Map a load opcode to its corresponding store opcode.
 284   virtual int store_Opcode() const = 0;
 285 
 286   // Check if the load's memory input is a Phi node with the same control.
 287   bool is_instance_field_load_with_local_phi(Node* ctrl);
 288 
 289   Node* convert_to_unsigned_load(PhaseGVN& gvn);
 290   Node* convert_to_signed_load(PhaseGVN& gvn);
 291 
 292   bool  has_reinterpret_variant(const Type* rt);
 293   Node* convert_to_reinterpret_load(PhaseGVN& gvn, const Type* rt);
 294 
 295   ControlDependency control_dependency() const { return _control_dependency; }
 296   bool has_unknown_control_dependency() const  { return _control_dependency == UnknownControl; }
 297   bool has_pinned_control_dependency() const   { return _control_dependency == Pinned; }
 298 
 299   LoadNode* pin_array_access_node() const;
 300 
 301 #ifndef PRODUCT
 302   virtual void dump_spec(outputStream *st) const;
 303 #endif
 304 #ifdef ASSERT
 305   // Helper function to allow a raw load without control edge for some cases
 306   static bool is_immutable_value(Node* adr);
 307 #endif
 308 protected:
 309   const Type* load_array_final_field(const TypeKlassPtr *tkls,
 310                                      ciKlass* klass) const;
 311 
 312   Node* can_see_arraycopy_value(Node* st, PhaseGVN* phase) const;
 313 
 314   // depends_only_on_test is almost always true, and needs to be almost always
 315   // true to enable key hoisting & commoning optimizations.  However, for the
 316   // special case of RawPtr loads from TLS top & end, and other loads performed by
 317   // GC barriers, the control edge carries the dependence preventing hoisting past
 318   // a Safepoint instead of the memory edge.  (An unfortunate consequence of having
 319   // Safepoints not set Raw Memory; itself an unfortunate consequence of having Nodes
 320   // which produce results (new raw memory state) inside of loops preventing all
 321   // manner of other optimizations).  Basically, it's ugly but so is the alternative.
 322   // See comment in macro.cpp, around line 125 expand_allocate_common().
 323   virtual bool depends_only_on_test() const {
 324     return adr_type() != TypeRawPtr::BOTTOM && _control_dependency == DependsOnlyOnTest;
 325   }
 326 
 327   LoadNode* clone_pinned() const;
 328 };
 329 
 330 //------------------------------LoadBNode--------------------------------------
 331 // Load a byte (8bits signed) from memory
 332 class LoadBNode : public LoadNode {
 333 public:
 334   LoadBNode(Node *c, Node *mem, Node *adr, const TypePtr* at, const TypeInt *ti, MemOrd mo, ControlDependency control_dependency = DependsOnlyOnTest)
 335     : LoadNode(c, mem, adr, at, ti, mo, control_dependency) {}
 336   virtual int Opcode() const;
 337   virtual uint ideal_reg() const { return Op_RegI; }
 338   virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
 339   virtual const Type* Value(PhaseGVN* phase) const;
 340   virtual int store_Opcode() const { return Op_StoreB; }
 341   virtual BasicType memory_type() const { return T_BYTE; }
 342 };
 343 
 344 //------------------------------LoadUBNode-------------------------------------
 345 // Load a unsigned byte (8bits unsigned) from memory
 346 class LoadUBNode : public LoadNode {
 347 public:
 348   LoadUBNode(Node* c, Node* mem, Node* adr, const TypePtr* at, const TypeInt* ti, MemOrd mo, ControlDependency control_dependency = DependsOnlyOnTest)
 349     : LoadNode(c, mem, adr, at, ti, mo, control_dependency) {}
 350   virtual int Opcode() const;
 351   virtual uint ideal_reg() const { return Op_RegI; }
 352   virtual Node* Ideal(PhaseGVN *phase, bool can_reshape);
 353   virtual const Type* Value(PhaseGVN* phase) const;
 354   virtual int store_Opcode() const { return Op_StoreB; }
 355   virtual BasicType memory_type() const { return T_BYTE; }
 356 };
 357 
 358 //------------------------------LoadUSNode-------------------------------------
 359 // Load an unsigned short/char (16bits unsigned) from memory
 360 class LoadUSNode : public LoadNode {
 361 public:
 362   LoadUSNode(Node *c, Node *mem, Node *adr, const TypePtr* at, const TypeInt *ti, MemOrd mo, ControlDependency control_dependency = DependsOnlyOnTest)
 363     : LoadNode(c, mem, adr, at, ti, mo, control_dependency) {}
 364   virtual int Opcode() const;
 365   virtual uint ideal_reg() const { return Op_RegI; }
 366   virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
 367   virtual const Type* Value(PhaseGVN* phase) const;
 368   virtual int store_Opcode() const { return Op_StoreC; }
 369   virtual BasicType memory_type() const { return T_CHAR; }
 370 };
 371 
 372 //------------------------------LoadSNode--------------------------------------
 373 // Load a short (16bits signed) from memory
 374 class LoadSNode : public LoadNode {
 375 public:
 376   LoadSNode(Node *c, Node *mem, Node *adr, const TypePtr* at, const TypeInt *ti, MemOrd mo, ControlDependency control_dependency = DependsOnlyOnTest)
 377     : LoadNode(c, mem, adr, at, ti, mo, control_dependency) {}
 378   virtual int Opcode() const;
 379   virtual uint ideal_reg() const { return Op_RegI; }
 380   virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
 381   virtual const Type* Value(PhaseGVN* phase) const;
 382   virtual int store_Opcode() const { return Op_StoreC; }
 383   virtual BasicType memory_type() const { return T_SHORT; }
 384 };
 385 
 386 //------------------------------LoadINode--------------------------------------
 387 // Load an integer from memory
 388 class LoadINode : public LoadNode {
 389 public:
 390   LoadINode(Node *c, Node *mem, Node *adr, const TypePtr* at, const TypeInt *ti, MemOrd mo, ControlDependency control_dependency = DependsOnlyOnTest)
 391     : LoadNode(c, mem, adr, at, ti, mo, control_dependency) {}
 392   virtual int Opcode() const;
 393   virtual uint ideal_reg() const { return Op_RegI; }
 394   virtual int store_Opcode() const { return Op_StoreI; }
 395   virtual BasicType memory_type() const { return T_INT; }
 396 };
 397 
 398 //------------------------------LoadRangeNode----------------------------------
 399 // Load an array length from the array
 400 class LoadRangeNode : public LoadINode {
 401 public:
 402   LoadRangeNode(Node *c, Node *mem, Node *adr, const TypeInt *ti = TypeInt::POS)
 403     : LoadINode(c, mem, adr, TypeAryPtr::RANGE, ti, MemNode::unordered) {}
 404   virtual int Opcode() const;
 405   virtual const Type* Value(PhaseGVN* phase) const;
 406   virtual Node* Identity(PhaseGVN* phase);
 407   virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
 408 };
 409 
 410 //------------------------------LoadLNode--------------------------------------
 411 // Load a long from memory
 412 class LoadLNode : public LoadNode {
 413   virtual uint hash() const { return LoadNode::hash() + _require_atomic_access; }
 414   virtual bool cmp( const Node &n ) const {
 415     return _require_atomic_access == ((LoadLNode&)n)._require_atomic_access
 416       && LoadNode::cmp(n);
 417   }
 418   virtual uint size_of() const { return sizeof(*this); }
 419   const bool _require_atomic_access;  // is piecewise load forbidden?
 420 
 421 public:
 422   LoadLNode(Node *c, Node *mem, Node *adr, const TypePtr* at, const TypeLong *tl,
 423             MemOrd mo, ControlDependency control_dependency = DependsOnlyOnTest, bool require_atomic_access = false)
 424     : LoadNode(c, mem, adr, at, tl, mo, control_dependency), _require_atomic_access(require_atomic_access) {}
 425   virtual int Opcode() const;
 426   virtual uint ideal_reg() const { return Op_RegL; }
 427   virtual int store_Opcode() const { return Op_StoreL; }
 428   virtual BasicType memory_type() const { return T_LONG; }
 429   bool require_atomic_access() const { return _require_atomic_access; }
 430 
 431 #ifndef PRODUCT
 432   virtual void dump_spec(outputStream *st) const {
 433     LoadNode::dump_spec(st);
 434     if (_require_atomic_access)  st->print(" Atomic!");
 435   }
 436 #endif
 437 };
 438 
 439 //------------------------------LoadL_unalignedNode----------------------------
 440 // Load a long from unaligned memory
 441 class LoadL_unalignedNode : public LoadLNode {
 442 public:
 443   LoadL_unalignedNode(Node *c, Node *mem, Node *adr, const TypePtr* at, MemOrd mo, ControlDependency control_dependency = DependsOnlyOnTest)
 444     : LoadLNode(c, mem, adr, at, TypeLong::LONG, mo, control_dependency) {}
 445   virtual int Opcode() const;
 446 };
 447 
 448 //------------------------------LoadFNode--------------------------------------
 449 // Load a float (64 bits) from memory
 450 class LoadFNode : public LoadNode {
 451 public:
 452   LoadFNode(Node *c, Node *mem, Node *adr, const TypePtr* at, const Type *t, MemOrd mo, ControlDependency control_dependency = DependsOnlyOnTest)
 453     : LoadNode(c, mem, adr, at, t, mo, control_dependency) {}
 454   virtual int Opcode() const;
 455   virtual uint ideal_reg() const { return Op_RegF; }
 456   virtual int store_Opcode() const { return Op_StoreF; }
 457   virtual BasicType memory_type() const { return T_FLOAT; }
 458 };
 459 
 460 //------------------------------LoadDNode--------------------------------------
 461 // Load a double (64 bits) from memory
 462 class LoadDNode : public LoadNode {
 463   virtual uint hash() const { return LoadNode::hash() + _require_atomic_access; }
 464   virtual bool cmp( const Node &n ) const {
 465     return _require_atomic_access == ((LoadDNode&)n)._require_atomic_access
 466       && LoadNode::cmp(n);
 467   }
 468   virtual uint size_of() const { return sizeof(*this); }
 469   const bool _require_atomic_access;  // is piecewise load forbidden?
 470 
 471 public:
 472   LoadDNode(Node *c, Node *mem, Node *adr, const TypePtr* at, const Type *t,
 473             MemOrd mo, ControlDependency control_dependency = DependsOnlyOnTest, bool require_atomic_access = false)
 474     : LoadNode(c, mem, adr, at, t, mo, control_dependency), _require_atomic_access(require_atomic_access) {}
 475   virtual int Opcode() const;
 476   virtual uint ideal_reg() const { return Op_RegD; }
 477   virtual int store_Opcode() const { return Op_StoreD; }
 478   virtual BasicType memory_type() const { return T_DOUBLE; }
 479   bool require_atomic_access() const { return _require_atomic_access; }
 480 
 481 #ifndef PRODUCT
 482   virtual void dump_spec(outputStream *st) const {
 483     LoadNode::dump_spec(st);
 484     if (_require_atomic_access)  st->print(" Atomic!");
 485   }
 486 #endif
 487 };
 488 
 489 //------------------------------LoadD_unalignedNode----------------------------
 490 // Load a double from unaligned memory
 491 class LoadD_unalignedNode : public LoadDNode {
 492 public:
 493   LoadD_unalignedNode(Node *c, Node *mem, Node *adr, const TypePtr* at, MemOrd mo, ControlDependency control_dependency = DependsOnlyOnTest)
 494     : LoadDNode(c, mem, adr, at, Type::DOUBLE, mo, control_dependency) {}
 495   virtual int Opcode() const;
 496 };
 497 
 498 //------------------------------LoadPNode--------------------------------------
 499 // Load a pointer from memory (either object or array)
 500 class LoadPNode : public LoadNode {
 501 public:
 502   LoadPNode(Node *c, Node *mem, Node *adr, const TypePtr *at, const TypePtr* t, MemOrd mo, ControlDependency control_dependency = DependsOnlyOnTest)
 503     : LoadNode(c, mem, adr, at, t, mo, control_dependency) {}
 504   virtual int Opcode() const;
 505   virtual uint ideal_reg() const { return Op_RegP; }
 506   virtual int store_Opcode() const { return Op_StoreP; }
 507   virtual BasicType memory_type() const { return T_ADDRESS; }
 508 };
 509 
 510 
 511 //------------------------------LoadNNode--------------------------------------
 512 // Load a narrow oop from memory (either object or array)
 513 class LoadNNode : public LoadNode {
 514 public:
 515   LoadNNode(Node *c, Node *mem, Node *adr, const TypePtr *at, const Type* t, MemOrd mo, ControlDependency control_dependency = DependsOnlyOnTest)
 516     : LoadNode(c, mem, adr, at, t, mo, control_dependency) {}
 517   virtual int Opcode() const;
 518   virtual uint ideal_reg() const { return Op_RegN; }
 519   virtual int store_Opcode() const { return Op_StoreN; }
 520   virtual BasicType memory_type() const { return T_NARROWOOP; }
 521 };
 522 
 523 //------------------------------LoadKlassNode----------------------------------
 524 // Load a Klass from an object
 525 class LoadKlassNode : public LoadPNode {
 526 protected:
 527   // In most cases, LoadKlassNode does not have the control input set. If the control
 528   // input is set, it must not be removed (by LoadNode::Ideal()).
 529   virtual bool can_remove_control() const;
 530 public:
 531   LoadKlassNode(Node *c, Node *mem, Node *adr, const TypePtr *at, const TypeKlassPtr *tk, MemOrd mo)
 532     : LoadPNode(c, mem, adr, at, tk, mo) {}
 533   virtual int Opcode() const;
 534   virtual const Type* Value(PhaseGVN* phase) const;
 535   virtual Node* Identity(PhaseGVN* phase);
 536   virtual bool depends_only_on_test() const { return true; }
 537 
 538   // Polymorphic factory method:
 539   static Node* make(PhaseGVN& gvn, Node* ctl, Node* mem, Node* adr, const TypePtr* at,
 540                     const TypeKlassPtr* tk = TypeInstKlassPtr::OBJECT);
 541 };
 542 
 543 //------------------------------LoadNKlassNode---------------------------------
 544 // Load a narrow Klass from an object.
 545 class LoadNKlassNode : public LoadNNode {
 546 public:
 547   LoadNKlassNode(Node *c, Node *mem, Node *adr, const TypePtr *at, const TypeNarrowKlass *tk, MemOrd mo)
 548     : LoadNNode(c, mem, adr, at, tk, mo) {}
 549   virtual int Opcode() const;
 550   virtual uint ideal_reg() const { return Op_RegN; }
 551   virtual int store_Opcode() const { return Op_StoreNKlass; }
 552   virtual BasicType memory_type() const { return T_NARROWKLASS; }
 553 
 554   virtual const Type* Value(PhaseGVN* phase) const;
 555   virtual Node* Identity(PhaseGVN* phase);
 556   virtual bool depends_only_on_test() const { return true; }
 557 };
 558 
 559 
 560 //------------------------------StoreNode--------------------------------------
 561 // Store value; requires Store, Address and Value
 562 class StoreNode : public MemNode {
 563 private:
 564   // On platforms with weak memory ordering (e.g., PPC, Ia64) we distinguish
 565   // stores that can be reordered, and such requiring release semantics to
 566   // adhere to the Java specification.  The required behaviour is stored in
 567   // this field.
 568   const MemOrd _mo;
 569   // Needed for proper cloning.
 570   virtual uint size_of() const { return sizeof(*this); }
 571 protected:
 572   virtual bool cmp( const Node &n ) const;
 573   virtual bool depends_only_on_test() const { return false; }
 574 
 575   Node *Ideal_masked_input       (PhaseGVN *phase, uint mask);
 576   Node *Ideal_sign_extended_input(PhaseGVN *phase, int  num_bits);
 577 
 578 public:
 579   // We must ensure that stores of object references will be visible
 580   // only after the object's initialization. So the callers of this
 581   // procedure must indicate that the store requires `release'
 582   // semantics, if the stored value is an object reference that might
 583   // point to a new object and may become externally visible.
 584   StoreNode(Node *c, Node *mem, Node *adr, const TypePtr* at, Node *val, MemOrd mo)
 585     : MemNode(c, mem, adr, at, val), _mo(mo) {
 586     init_class_id(Class_Store);
 587   }
 588   StoreNode(Node *c, Node *mem, Node *adr, const TypePtr* at, Node *val, Node *oop_store, MemOrd mo)
 589     : MemNode(c, mem, adr, at, val, oop_store), _mo(mo) {
 590     init_class_id(Class_Store);
 591   }
 592 
 593   inline bool is_unordered() const { return !is_release(); }
 594   inline bool is_release() const {
 595     assert((_mo == unordered || _mo == release), "unexpected");
 596     return _mo == release;
 597   }
 598 
 599   // Conservatively release stores of object references in order to
 600   // ensure visibility of object initialization.
 601   static inline MemOrd release_if_reference(const BasicType t) {
 602 #ifdef AARCH64
 603     // AArch64 doesn't need a release store here because object
 604     // initialization contains the necessary barriers.
 605     return unordered;
 606 #else
 607     const MemOrd mo = (t == T_ARRAY ||
 608                        t == T_ADDRESS || // Might be the address of an object reference (`boxing').
 609                        t == T_OBJECT) ? release : unordered;
 610     return mo;
 611 #endif
 612   }
 613 
 614   // Polymorphic factory method
 615   //
 616   // We must ensure that stores of object references will be visible
 617   // only after the object's initialization. So the callers of this
 618   // procedure must indicate that the store requires `release'
 619   // semantics, if the stored value is an object reference that might
 620   // point to a new object and may become externally visible.
 621   static StoreNode* make(PhaseGVN& gvn, Node* c, Node* mem, Node* adr,
 622                          const TypePtr* at, Node* val, BasicType bt,
 623                          MemOrd mo, bool require_atomic_access = false);
 624 
 625   virtual uint hash() const;    // Check the type
 626 
 627   // If the store is to Field memory and the pointer is non-null, we can
 628   // zero out the control input.
 629   virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
 630 
 631   // Compute a new Type for this node.  Basically we just do the pre-check,
 632   // then call the virtual add() to set the type.
 633   virtual const Type* Value(PhaseGVN* phase) const;
 634 
 635   // Check for identity function on memory (Load then Store at same address)
 636   virtual Node* Identity(PhaseGVN* phase);
 637 
 638   // Do not match memory edge
 639   virtual uint match_edge(uint idx) const;
 640 
 641   virtual const Type *bottom_type() const;  // returns Type::MEMORY
 642 
 643   // Map a store opcode to its corresponding own opcode, trivially.
 644   virtual int store_Opcode() const { return Opcode(); }
 645 
 646   // have all possible loads of the value stored been optimized away?
 647   bool value_never_loaded(PhaseValues* phase) const;
 648 
 649   bool  has_reinterpret_variant(const Type* vt);
 650   Node* convert_to_reinterpret_store(PhaseGVN& gvn, Node* val, const Type* vt);
 651 
 652   MemBarNode* trailing_membar() const;
 653 };
 654 
 655 //------------------------------StoreBNode-------------------------------------
 656 // Store byte to memory
 657 class StoreBNode : public StoreNode {
 658 public:
 659   StoreBNode(Node *c, Node *mem, Node *adr, const TypePtr* at, Node *val, MemOrd mo)
 660     : StoreNode(c, mem, adr, at, val, mo) {}
 661   virtual int Opcode() const;
 662   virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
 663   virtual BasicType memory_type() const { return T_BYTE; }
 664 };
 665 
 666 //------------------------------StoreCNode-------------------------------------
 667 // Store char/short to memory
 668 class StoreCNode : public StoreNode {
 669 public:
 670   StoreCNode(Node *c, Node *mem, Node *adr, const TypePtr* at, Node *val, MemOrd mo)
 671     : StoreNode(c, mem, adr, at, val, mo) {}
 672   virtual int Opcode() const;
 673   virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
 674   virtual BasicType memory_type() const { return T_CHAR; }
 675 };
 676 
 677 //------------------------------StoreINode-------------------------------------
 678 // Store int to memory
 679 class StoreINode : public StoreNode {
 680 public:
 681   StoreINode(Node *c, Node *mem, Node *adr, const TypePtr* at, Node *val, MemOrd mo)
 682     : StoreNode(c, mem, adr, at, val, mo) {}
 683   virtual int Opcode() const;
 684   virtual BasicType memory_type() const { return T_INT; }
 685 };
 686 
 687 //------------------------------StoreLNode-------------------------------------
 688 // Store long to memory
 689 class StoreLNode : public StoreNode {
 690   virtual uint hash() const { return StoreNode::hash() + _require_atomic_access; }
 691   virtual bool cmp( const Node &n ) const {
 692     return _require_atomic_access == ((StoreLNode&)n)._require_atomic_access
 693       && StoreNode::cmp(n);
 694   }
 695   virtual uint size_of() const { return sizeof(*this); }
 696   const bool _require_atomic_access;  // is piecewise store forbidden?
 697 
 698 public:
 699   StoreLNode(Node *c, Node *mem, Node *adr, const TypePtr* at, Node *val, MemOrd mo, bool require_atomic_access = false)
 700     : StoreNode(c, mem, adr, at, val, mo), _require_atomic_access(require_atomic_access) {}
 701   virtual int Opcode() const;
 702   virtual BasicType memory_type() const { return T_LONG; }
 703   bool require_atomic_access() const { return _require_atomic_access; }
 704 
 705 #ifndef PRODUCT
 706   virtual void dump_spec(outputStream *st) const {
 707     StoreNode::dump_spec(st);
 708     if (_require_atomic_access)  st->print(" Atomic!");
 709   }
 710 #endif
 711 };
 712 
 713 //------------------------------StoreFNode-------------------------------------
 714 // Store float to memory
 715 class StoreFNode : public StoreNode {
 716 public:
 717   StoreFNode(Node *c, Node *mem, Node *adr, const TypePtr* at, Node *val, MemOrd mo)
 718     : StoreNode(c, mem, adr, at, val, mo) {}
 719   virtual int Opcode() const;
 720   virtual BasicType memory_type() const { return T_FLOAT; }
 721 };
 722 
 723 //------------------------------StoreDNode-------------------------------------
 724 // Store double to memory
 725 class StoreDNode : public StoreNode {
 726   virtual uint hash() const { return StoreNode::hash() + _require_atomic_access; }
 727   virtual bool cmp( const Node &n ) const {
 728     return _require_atomic_access == ((StoreDNode&)n)._require_atomic_access
 729       && StoreNode::cmp(n);
 730   }
 731   virtual uint size_of() const { return sizeof(*this); }
 732   const bool _require_atomic_access;  // is piecewise store forbidden?
 733 public:
 734   StoreDNode(Node *c, Node *mem, Node *adr, const TypePtr* at, Node *val,
 735              MemOrd mo, bool require_atomic_access = false)
 736     : StoreNode(c, mem, adr, at, val, mo), _require_atomic_access(require_atomic_access) {}
 737   virtual int Opcode() const;
 738   virtual BasicType memory_type() const { return T_DOUBLE; }
 739   bool require_atomic_access() const { return _require_atomic_access; }
 740 
 741 #ifndef PRODUCT
 742   virtual void dump_spec(outputStream *st) const {
 743     StoreNode::dump_spec(st);
 744     if (_require_atomic_access)  st->print(" Atomic!");
 745   }
 746 #endif
 747 
 748 };
 749 
 750 //------------------------------StorePNode-------------------------------------
 751 // Store pointer to memory
 752 class StorePNode : public StoreNode {
 753 public:
 754   StorePNode(Node *c, Node *mem, Node *adr, const TypePtr* at, Node *val, MemOrd mo)
 755     : StoreNode(c, mem, adr, at, val, mo) {}
 756   virtual int Opcode() const;
 757   virtual BasicType memory_type() const { return T_ADDRESS; }
 758 };
 759 
 760 //------------------------------StoreNNode-------------------------------------
 761 // Store narrow oop to memory
 762 class StoreNNode : public StoreNode {
 763 public:
 764   StoreNNode(Node *c, Node *mem, Node *adr, const TypePtr* at, Node *val, MemOrd mo)
 765     : StoreNode(c, mem, adr, at, val, mo) {}
 766   virtual int Opcode() const;
 767   virtual BasicType memory_type() const { return T_NARROWOOP; }
 768 };
 769 
 770 //------------------------------StoreNKlassNode--------------------------------------
 771 // Store narrow klass to memory
 772 class StoreNKlassNode : public StoreNNode {
 773 public:
 774   StoreNKlassNode(Node *c, Node *mem, Node *adr, const TypePtr* at, Node *val, MemOrd mo)
 775     : StoreNNode(c, mem, adr, at, val, mo) {}
 776   virtual int Opcode() const;
 777   virtual BasicType memory_type() const { return T_NARROWKLASS; }
 778 };
 779 
 780 //------------------------------StoreCMNode-----------------------------------
 781 // Store card-mark byte to memory for CM
 782 // The last StoreCM before a SafePoint must be preserved and occur after its "oop" store
 783 // Preceding equivalent StoreCMs may be eliminated.
 784 class StoreCMNode : public StoreNode {
 785  private:
 786   virtual uint hash() const { return StoreNode::hash() + _oop_alias_idx; }
 787   virtual bool cmp( const Node &n ) const {
 788     return _oop_alias_idx == ((StoreCMNode&)n)._oop_alias_idx
 789       && StoreNode::cmp(n);
 790   }
 791   virtual uint size_of() const { return sizeof(*this); }
 792   int _oop_alias_idx;   // The alias_idx of OopStore
 793 
 794 public:
 795   StoreCMNode( Node *c, Node *mem, Node *adr, const TypePtr* at, Node *val, Node *oop_store, int oop_alias_idx ) :
 796     StoreNode(c, mem, adr, at, val, oop_store, MemNode::release),
 797     _oop_alias_idx(oop_alias_idx) {
 798     assert(_oop_alias_idx >= Compile::AliasIdxRaw ||
 799            (_oop_alias_idx == Compile::AliasIdxBot && !Compile::current()->do_aliasing()),
 800            "bad oop alias idx");
 801   }
 802   virtual int Opcode() const;
 803   virtual Node* Identity(PhaseGVN* phase);
 804   virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
 805   virtual const Type* Value(PhaseGVN* phase) const;
 806   virtual BasicType memory_type() const { return T_VOID; } // unspecific
 807   int oop_alias_idx() const { return _oop_alias_idx; }
 808 };
 809 
 810 //------------------------------SCMemProjNode---------------------------------------
 811 // This class defines a projection of the memory  state of a store conditional node.
 812 // These nodes return a value, but also update memory.
 813 class SCMemProjNode : public ProjNode {
 814 public:
 815   enum {SCMEMPROJCON = (uint)-2};
 816   SCMemProjNode( Node *src) : ProjNode( src, SCMEMPROJCON) { }
 817   virtual int Opcode() const;
 818   virtual bool      is_CFG() const  { return false; }
 819   virtual const Type *bottom_type() const {return Type::MEMORY;}
 820   virtual const TypePtr *adr_type() const {
 821     Node* ctrl = in(0);
 822     if (ctrl == nullptr)  return nullptr; // node is dead
 823     return ctrl->in(MemNode::Memory)->adr_type();
 824   }
 825   virtual uint ideal_reg() const { return 0;} // memory projections don't have a register
 826   virtual const Type* Value(PhaseGVN* phase) const;
 827 #ifndef PRODUCT
 828   virtual void dump_spec(outputStream *st) const {};
 829 #endif
 830 };
 831 
 832 //------------------------------LoadStoreNode---------------------------
 833 // Note: is_Mem() method returns 'true' for this class.
 834 class LoadStoreNode : public Node {
 835 private:
 836   const Type* const _type;      // What kind of value is loaded?
 837   const TypePtr* _adr_type;     // What kind of memory is being addressed?
 838   uint8_t _barrier_data;        // Bit field with barrier information
 839   virtual uint size_of() const; // Size is bigger
 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 class TypePtr *adr_type() const { return _adr_type; }  // returns bottom_type of address
 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 public:
1099   ClearArrayNode( Node *ctrl, Node *arymem, Node *word_cnt, Node *base, bool is_large)
1100     : Node(ctrl,arymem,word_cnt,base), _is_large(is_large) {
1101     init_class_id(Class_ClearArray);
1102   }
1103   virtual int         Opcode() const;
1104   virtual const Type *bottom_type() const { return Type::MEMORY; }
1105   // ClearArray modifies array elements, and so affects only the
1106   // array memory addressed by the bottom_type of its base address.
1107   virtual const class TypePtr *adr_type() const;
1108   virtual Node* Identity(PhaseGVN* phase);
1109   virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
1110   virtual uint match_edge(uint idx) const;
1111   bool is_large() const { return _is_large; }
1112 
1113   // Clear the given area of an object or array.
1114   // The start offset must always be aligned mod BytesPerInt.
1115   // The end offset must always be aligned mod BytesPerLong.
1116   // Return the new memory.
1117   static Node* clear_memory(Node* control, Node* mem, Node* dest,
1118                             intptr_t start_offset,
1119                             intptr_t end_offset,
1120                             PhaseGVN* phase);
1121   static Node* clear_memory(Node* control, Node* mem, Node* dest,
1122                             intptr_t start_offset,
1123                             Node* end_offset,
1124                             PhaseGVN* phase);
1125   static Node* clear_memory(Node* control, Node* mem, Node* dest,
1126                             Node* start_offset,
1127                             Node* end_offset,
1128                             PhaseGVN* phase);
1129   // Return allocation input memory edge if it is different instance
1130   // or itself if it is the one we are looking for.
1131   static bool step_through(Node** np, uint instance_id, PhaseValues* phase);
1132 };
1133 
1134 //------------------------------MemBar-----------------------------------------
1135 // There are different flavors of Memory Barriers to match the Java Memory
1136 // Model.  Monitor-enter and volatile-load act as Acquires: no following ref
1137 // can be moved to before them.  We insert a MemBar-Acquire after a FastLock or
1138 // volatile-load.  Monitor-exit and volatile-store act as Release: no
1139 // preceding ref can be moved to after them.  We insert a MemBar-Release
1140 // before a FastUnlock or volatile-store.  All volatiles need to be
1141 // serialized, so we follow all volatile-stores with a MemBar-Volatile to
1142 // separate it from any following volatile-load.
1143 class MemBarNode: public MultiNode {
1144   virtual uint hash() const ;                  // { return NO_HASH; }
1145   virtual bool cmp( const Node &n ) const ;    // Always fail, except on self
1146 
1147   virtual uint size_of() const { return sizeof(*this); }
1148   // Memory type this node is serializing.  Usually either rawptr or bottom.
1149   const TypePtr* _adr_type;
1150 
1151   // How is this membar related to a nearby memory access?
1152   enum {
1153     Standalone,
1154     TrailingLoad,
1155     TrailingStore,
1156     LeadingStore,
1157     TrailingLoadStore,
1158     LeadingLoadStore,
1159     TrailingPartialArrayCopy
1160   } _kind;
1161 
1162 #ifdef ASSERT
1163   uint _pair_idx;
1164 #endif
1165 
1166 public:
1167   enum {
1168     Precedent = TypeFunc::Parms  // optional edge to force precedence
1169   };
1170   MemBarNode(Compile* C, int alias_idx, Node* precedent);
1171   virtual int Opcode() const = 0;
1172   virtual const class TypePtr *adr_type() const { return _adr_type; }
1173   virtual const Type* Value(PhaseGVN* phase) const;
1174   virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
1175   virtual uint match_edge(uint idx) const { return 0; }
1176   virtual const Type *bottom_type() const { return TypeTuple::MEMBAR; }
1177   virtual Node *match( const ProjNode *proj, const Matcher *m );
1178   // Factory method.  Builds a wide or narrow membar.
1179   // Optional 'precedent' becomes an extra edge if not null.
1180   static MemBarNode* make(Compile* C, int opcode,
1181                           int alias_idx = Compile::AliasIdxBot,
1182                           Node* precedent = nullptr);
1183 
1184   MemBarNode* trailing_membar() const;
1185   MemBarNode* leading_membar() const;
1186 
1187   void set_trailing_load() { _kind = TrailingLoad; }
1188   bool trailing_load() const { return _kind == TrailingLoad; }
1189   bool trailing_store() const { return _kind == TrailingStore; }
1190   bool leading_store() const { return _kind == LeadingStore; }
1191   bool trailing_load_store() const { return _kind == TrailingLoadStore; }
1192   bool leading_load_store() const { return _kind == LeadingLoadStore; }
1193   bool trailing() const { return _kind == TrailingLoad || _kind == TrailingStore || _kind == TrailingLoadStore; }
1194   bool leading() const { return _kind == LeadingStore || _kind == LeadingLoadStore; }
1195   bool standalone() const { return _kind == Standalone; }
1196   void set_trailing_partial_array_copy() { _kind = TrailingPartialArrayCopy; }
1197   bool trailing_partial_array_copy() const { return _kind == TrailingPartialArrayCopy; }
1198 
1199   static void set_store_pair(MemBarNode* leading, MemBarNode* trailing);
1200   static void set_load_store_pair(MemBarNode* leading, MemBarNode* trailing);
1201 
1202   void remove(PhaseIterGVN *igvn);
1203 };
1204 
1205 // "Acquire" - no following ref can move before (but earlier refs can
1206 // follow, like an early Load stalled in cache).  Requires multi-cpu
1207 // visibility.  Inserted after a volatile load.
1208 class MemBarAcquireNode: public MemBarNode {
1209 public:
1210   MemBarAcquireNode(Compile* C, int alias_idx, Node* precedent)
1211     : MemBarNode(C, alias_idx, precedent) {}
1212   virtual int Opcode() const;
1213 };
1214 
1215 // "Acquire" - no following ref can move before (but earlier refs can
1216 // follow, like an early Load stalled in cache).  Requires multi-cpu
1217 // visibility.  Inserted independent of any load, as required
1218 // for intrinsic Unsafe.loadFence().
1219 class LoadFenceNode: public MemBarNode {
1220 public:
1221   LoadFenceNode(Compile* C, int alias_idx, Node* precedent)
1222     : MemBarNode(C, alias_idx, precedent) {}
1223   virtual int Opcode() const;
1224 };
1225 
1226 // "Release" - no earlier ref can move after (but later refs can move
1227 // up, like a speculative pipelined cache-hitting Load).  Requires
1228 // multi-cpu visibility.  Inserted before a volatile store.
1229 class MemBarReleaseNode: public MemBarNode {
1230 public:
1231   MemBarReleaseNode(Compile* C, int alias_idx, Node* precedent)
1232     : MemBarNode(C, alias_idx, precedent) {}
1233   virtual int Opcode() const;
1234 };
1235 
1236 // "Release" - no earlier ref can move after (but later refs can move
1237 // up, like a speculative pipelined cache-hitting Load).  Requires
1238 // multi-cpu visibility.  Inserted independent of any store, as required
1239 // for intrinsic Unsafe.storeFence().
1240 class StoreFenceNode: public MemBarNode {
1241 public:
1242   StoreFenceNode(Compile* C, int alias_idx, Node* precedent)
1243     : MemBarNode(C, alias_idx, precedent) {}
1244   virtual int Opcode() const;
1245 };
1246 
1247 // "Acquire" - no following ref can move before (but earlier refs can
1248 // follow, like an early Load stalled in cache).  Requires multi-cpu
1249 // visibility.  Inserted after a FastLock.
1250 class MemBarAcquireLockNode: public MemBarNode {
1251 public:
1252   MemBarAcquireLockNode(Compile* C, int alias_idx, Node* precedent)
1253     : MemBarNode(C, alias_idx, precedent) {}
1254   virtual int Opcode() const;
1255 };
1256 
1257 // "Release" - no earlier ref can move after (but later refs can move
1258 // up, like a speculative pipelined cache-hitting Load).  Requires
1259 // multi-cpu visibility.  Inserted before a FastUnLock.
1260 class MemBarReleaseLockNode: public MemBarNode {
1261 public:
1262   MemBarReleaseLockNode(Compile* C, int alias_idx, Node* precedent)
1263     : MemBarNode(C, alias_idx, precedent) {}
1264   virtual int Opcode() const;
1265 };
1266 
1267 class MemBarStoreStoreNode: public MemBarNode {
1268 public:
1269   MemBarStoreStoreNode(Compile* C, int alias_idx, Node* precedent)
1270     : MemBarNode(C, alias_idx, precedent) {
1271     init_class_id(Class_MemBarStoreStore);
1272   }
1273   virtual int Opcode() const;
1274 };
1275 
1276 class StoreStoreFenceNode: public MemBarNode {
1277 public:
1278   StoreStoreFenceNode(Compile* C, int alias_idx, Node* precedent)
1279     : MemBarNode(C, alias_idx, precedent) {}
1280   virtual int Opcode() const;
1281 };
1282 
1283 // Ordering between a volatile store and a following volatile load.
1284 // Requires multi-CPU visibility?
1285 class MemBarVolatileNode: public MemBarNode {
1286 public:
1287   MemBarVolatileNode(Compile* C, int alias_idx, Node* precedent)
1288     : MemBarNode(C, alias_idx, precedent) {}
1289   virtual int Opcode() const;
1290 };
1291 
1292 // Ordering within the same CPU.  Used to order unsafe memory references
1293 // inside the compiler when we lack alias info.  Not needed "outside" the
1294 // compiler because the CPU does all the ordering for us.
1295 class MemBarCPUOrderNode: public MemBarNode {
1296 public:
1297   MemBarCPUOrderNode(Compile* C, int alias_idx, Node* precedent)
1298     : MemBarNode(C, alias_idx, precedent) {}
1299   virtual int Opcode() const;
1300   virtual uint ideal_reg() const { return 0; } // not matched in the AD file
1301 };
1302 
1303 class OnSpinWaitNode: public MemBarNode {
1304 public:
1305   OnSpinWaitNode(Compile* C, int alias_idx, Node* precedent)
1306     : MemBarNode(C, alias_idx, precedent) {}
1307   virtual int Opcode() const;
1308 };
1309 
1310 // Isolation of object setup after an AllocateNode and before next safepoint.
1311 // (See comment in memnode.cpp near InitializeNode::InitializeNode for semantics.)
1312 class InitializeNode: public MemBarNode {
1313   friend class AllocateNode;
1314 
1315   enum {
1316     Incomplete    = 0,
1317     Complete      = 1,
1318     WithArraycopy = 2
1319   };
1320   int _is_complete;
1321 
1322   bool _does_not_escape;
1323 
1324 public:
1325   enum {
1326     Control    = TypeFunc::Control,
1327     Memory     = TypeFunc::Memory,     // MergeMem for states affected by this op
1328     RawAddress = TypeFunc::Parms+0,    // the newly-allocated raw address
1329     RawStores  = TypeFunc::Parms+1     // zero or more stores (or TOP)
1330   };
1331 
1332   InitializeNode(Compile* C, int adr_type, Node* rawoop);
1333   virtual int Opcode() const;
1334   virtual uint size_of() const { return sizeof(*this); }
1335   virtual uint ideal_reg() const { return 0; } // not matched in the AD file
1336   virtual const RegMask &in_RegMask(uint) const;  // mask for RawAddress
1337 
1338   // Manage incoming memory edges via a MergeMem on in(Memory):
1339   Node* memory(uint alias_idx);
1340 
1341   // The raw memory edge coming directly from the Allocation.
1342   // The contents of this memory are *always* all-zero-bits.
1343   Node* zero_memory() { return memory(Compile::AliasIdxRaw); }
1344 
1345   // Return the corresponding allocation for this initialization (or null if none).
1346   // (Note: Both InitializeNode::allocation and AllocateNode::initialization
1347   // are defined in graphKit.cpp, which sets up the bidirectional relation.)
1348   AllocateNode* allocation();
1349 
1350   // Anything other than zeroing in this init?
1351   bool is_non_zero();
1352 
1353   // An InitializeNode must completed before macro expansion is done.
1354   // Completion requires that the AllocateNode must be followed by
1355   // initialization of the new memory to zero, then to any initializers.
1356   bool is_complete() { return _is_complete != Incomplete; }
1357   bool is_complete_with_arraycopy() { return (_is_complete & WithArraycopy) != 0; }
1358 
1359   // Mark complete.  (Must not yet be complete.)
1360   void set_complete(PhaseGVN* phase);
1361   void set_complete_with_arraycopy() { _is_complete = Complete | WithArraycopy; }
1362 
1363   bool does_not_escape() { return _does_not_escape; }
1364   void set_does_not_escape() { _does_not_escape = true; }
1365 
1366 #ifdef ASSERT
1367   // ensure all non-degenerate stores are ordered and non-overlapping
1368   bool stores_are_sane(PhaseValues* phase);
1369 #endif //ASSERT
1370 
1371   // See if this store can be captured; return offset where it initializes.
1372   // Return 0 if the store cannot be moved (any sort of problem).
1373   intptr_t can_capture_store(StoreNode* st, PhaseGVN* phase, bool can_reshape);
1374 
1375   // Capture another store; reformat it to write my internal raw memory.
1376   // Return the captured copy, else null if there is some sort of problem.
1377   Node* capture_store(StoreNode* st, intptr_t start, PhaseGVN* phase, bool can_reshape);
1378 
1379   // Find captured store which corresponds to the range [start..start+size).
1380   // Return my own memory projection (meaning the initial zero bits)
1381   // if there is no such store.  Return null if there is a problem.
1382   Node* find_captured_store(intptr_t start, int size_in_bytes, PhaseValues* phase);
1383 
1384   // Called when the associated AllocateNode is expanded into CFG.
1385   Node* complete_stores(Node* rawctl, Node* rawmem, Node* rawptr,
1386                         intptr_t header_size, Node* size_in_bytes,
1387                         PhaseIterGVN* phase);
1388 
1389  private:
1390   void remove_extra_zeroes();
1391 
1392   // Find out where a captured store should be placed (or already is placed).
1393   int captured_store_insertion_point(intptr_t start, int size_in_bytes,
1394                                      PhaseValues* phase);
1395 
1396   static intptr_t get_store_offset(Node* st, PhaseValues* phase);
1397 
1398   Node* make_raw_address(intptr_t offset, PhaseGVN* phase);
1399 
1400   bool detect_init_independence(Node* value, PhaseGVN* phase);
1401 
1402   void coalesce_subword_stores(intptr_t header_size, Node* size_in_bytes,
1403                                PhaseGVN* phase);
1404 
1405   intptr_t find_next_fullword_store(uint i, PhaseGVN* phase);
1406 };
1407 
1408 //------------------------------MergeMem---------------------------------------
1409 // (See comment in memnode.cpp near MergeMemNode::MergeMemNode for semantics.)
1410 class MergeMemNode: public Node {
1411   virtual uint hash() const ;                  // { return NO_HASH; }
1412   virtual bool cmp( const Node &n ) const ;    // Always fail, except on self
1413   friend class MergeMemStream;
1414   MergeMemNode(Node* def);  // clients use MergeMemNode::make
1415 
1416 public:
1417   // If the input is a whole memory state, clone it with all its slices intact.
1418   // Otherwise, make a new memory state with just that base memory input.
1419   // In either case, the result is a newly created MergeMem.
1420   static MergeMemNode* make(Node* base_memory);
1421 
1422   virtual int Opcode() const;
1423   virtual Node* Identity(PhaseGVN* phase);
1424   virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
1425   virtual uint ideal_reg() const { return NotAMachineReg; }
1426   virtual uint match_edge(uint idx) const { return 0; }
1427   virtual const RegMask &out_RegMask() const;
1428   virtual const Type *bottom_type() const { return Type::MEMORY; }
1429   virtual const TypePtr *adr_type() const { return TypePtr::BOTTOM; }
1430   // sparse accessors
1431   // Fetch the previously stored "set_memory_at", or else the base memory.
1432   // (Caller should clone it if it is a phi-nest.)
1433   Node* memory_at(uint alias_idx) const;
1434   // set the memory, regardless of its previous value
1435   void set_memory_at(uint alias_idx, Node* n);
1436   // the "base" is the memory that provides the non-finite support
1437   Node* base_memory() const       { return in(Compile::AliasIdxBot); }
1438   // warning: setting the base can implicitly set any of the other slices too
1439   void set_base_memory(Node* def);
1440   // sentinel value which denotes a copy of the base memory:
1441   Node*   empty_memory() const    { return in(Compile::AliasIdxTop); }
1442   static Node* make_empty_memory(); // where the sentinel comes from
1443   bool is_empty_memory(Node* n) const { assert((n == empty_memory()) == n->is_top(), "sanity"); return n->is_top(); }
1444   // hook for the iterator, to perform any necessary setup
1445   void iteration_setup(const MergeMemNode* other = nullptr);
1446   // push sentinels until I am at least as long as the other (semantic no-op)
1447   void grow_to_match(const MergeMemNode* other);
1448   bool verify_sparse() const PRODUCT_RETURN0;
1449 #ifndef PRODUCT
1450   virtual void dump_spec(outputStream *st) const;
1451 #endif
1452 };
1453 
1454 class MergeMemStream : public StackObj {
1455  private:
1456   MergeMemNode*       _mm;
1457   const MergeMemNode* _mm2;  // optional second guy, contributes non-empty iterations
1458   Node*               _mm_base;  // loop-invariant base memory of _mm
1459   int                 _idx;
1460   int                 _cnt;
1461   Node*               _mem;
1462   Node*               _mem2;
1463   int                 _cnt2;
1464 
1465   void init(MergeMemNode* mm, const MergeMemNode* mm2 = nullptr) {
1466     // subsume_node will break sparseness at times, whenever a memory slice
1467     // folds down to a copy of the base ("fat") memory.  In such a case,
1468     // the raw edge will update to base, although it should be top.
1469     // This iterator will recognize either top or base_memory as an
1470     // "empty" slice.  See is_empty, is_empty2, and next below.
1471     //
1472     // The sparseness property is repaired in MergeMemNode::Ideal.
1473     // As long as access to a MergeMem goes through this iterator
1474     // or the memory_at accessor, flaws in the sparseness will
1475     // never be observed.
1476     //
1477     // Also, iteration_setup repairs sparseness.
1478     assert(mm->verify_sparse(), "please, no dups of base");
1479     assert(mm2==nullptr || mm2->verify_sparse(), "please, no dups of base");
1480 
1481     _mm  = mm;
1482     _mm_base = mm->base_memory();
1483     _mm2 = mm2;
1484     _cnt = mm->req();
1485     _idx = Compile::AliasIdxBot-1; // start at the base memory
1486     _mem = nullptr;
1487     _mem2 = nullptr;
1488   }
1489 
1490 #ifdef ASSERT
1491   Node* check_memory() const {
1492     if (at_base_memory())
1493       return _mm->base_memory();
1494     else if ((uint)_idx < _mm->req() && !_mm->in(_idx)->is_top())
1495       return _mm->memory_at(_idx);
1496     else
1497       return _mm_base;
1498   }
1499   Node* check_memory2() const {
1500     return at_base_memory()? _mm2->base_memory(): _mm2->memory_at(_idx);
1501   }
1502 #endif
1503 
1504   static bool match_memory(Node* mem, const MergeMemNode* mm, int idx) PRODUCT_RETURN0;
1505   void assert_synch() const {
1506     assert(!_mem || _idx >= _cnt || match_memory(_mem, _mm, _idx),
1507            "no side-effects except through the stream");
1508   }
1509 
1510  public:
1511 
1512   // expected usages:
1513   // for (MergeMemStream mms(mem->is_MergeMem()); next_non_empty(); ) { ... }
1514   // for (MergeMemStream mms(mem1, mem2); next_non_empty2(); ) { ... }
1515 
1516   // iterate over one merge
1517   MergeMemStream(MergeMemNode* mm) {
1518     mm->iteration_setup();
1519     init(mm);
1520     debug_only(_cnt2 = 999);
1521   }
1522   // iterate in parallel over two merges
1523   // only iterates through non-empty elements of mm2
1524   MergeMemStream(MergeMemNode* mm, const MergeMemNode* mm2) {
1525     assert(mm2, "second argument must be a MergeMem also");
1526     ((MergeMemNode*)mm2)->iteration_setup();  // update hidden state
1527     mm->iteration_setup(mm2);
1528     init(mm, mm2);
1529     _cnt2 = mm2->req();
1530   }
1531 #ifdef ASSERT
1532   ~MergeMemStream() {
1533     assert_synch();
1534   }
1535 #endif
1536 
1537   MergeMemNode* all_memory() const {
1538     return _mm;
1539   }
1540   Node* base_memory() const {
1541     assert(_mm_base == _mm->base_memory(), "no update to base memory, please");
1542     return _mm_base;
1543   }
1544   const MergeMemNode* all_memory2() const {
1545     assert(_mm2 != nullptr, "");
1546     return _mm2;
1547   }
1548   bool at_base_memory() const {
1549     return _idx == Compile::AliasIdxBot;
1550   }
1551   int alias_idx() const {
1552     assert(_mem, "must call next 1st");
1553     return _idx;
1554   }
1555 
1556   const TypePtr* adr_type() const {
1557     return Compile::current()->get_adr_type(alias_idx());
1558   }
1559 
1560   const TypePtr* adr_type(Compile* C) const {
1561     return C->get_adr_type(alias_idx());
1562   }
1563   bool is_empty() const {
1564     assert(_mem, "must call next 1st");
1565     assert(_mem->is_top() == (_mem==_mm->empty_memory()), "correct sentinel");
1566     return _mem->is_top();
1567   }
1568   bool is_empty2() const {
1569     assert(_mem2, "must call next 1st");
1570     assert(_mem2->is_top() == (_mem2==_mm2->empty_memory()), "correct sentinel");
1571     return _mem2->is_top();
1572   }
1573   Node* memory() const {
1574     assert(!is_empty(), "must not be empty");
1575     assert_synch();
1576     return _mem;
1577   }
1578   // get the current memory, regardless of empty or non-empty status
1579   Node* force_memory() const {
1580     assert(!is_empty() || !at_base_memory(), "");
1581     // Use _mm_base to defend against updates to _mem->base_memory().
1582     Node *mem = _mem->is_top() ? _mm_base : _mem;
1583     assert(mem == check_memory(), "");
1584     return mem;
1585   }
1586   Node* memory2() const {
1587     assert(_mem2 == check_memory2(), "");
1588     return _mem2;
1589   }
1590   void set_memory(Node* mem) {
1591     if (at_base_memory()) {
1592       // Note that this does not change the invariant _mm_base.
1593       _mm->set_base_memory(mem);
1594     } else {
1595       _mm->set_memory_at(_idx, mem);
1596     }
1597     _mem = mem;
1598     assert_synch();
1599   }
1600 
1601   // Recover from a side effect to the MergeMemNode.
1602   void set_memory() {
1603     _mem = _mm->in(_idx);
1604   }
1605 
1606   bool next()  { return next(false); }
1607   bool next2() { return next(true); }
1608 
1609   bool next_non_empty()  { return next_non_empty(false); }
1610   bool next_non_empty2() { return next_non_empty(true); }
1611   // next_non_empty2 can yield states where is_empty() is true
1612 
1613  private:
1614   // find the next item, which might be empty
1615   bool next(bool have_mm2) {
1616     assert((_mm2 != nullptr) == have_mm2, "use other next");
1617     assert_synch();
1618     if (++_idx < _cnt) {
1619       // Note:  This iterator allows _mm to be non-sparse.
1620       // It behaves the same whether _mem is top or base_memory.
1621       _mem = _mm->in(_idx);
1622       if (have_mm2)
1623         _mem2 = _mm2->in((_idx < _cnt2) ? _idx : Compile::AliasIdxTop);
1624       return true;
1625     }
1626     return false;
1627   }
1628 
1629   // find the next non-empty item
1630   bool next_non_empty(bool have_mm2) {
1631     while (next(have_mm2)) {
1632       if (!is_empty()) {
1633         // make sure _mem2 is filled in sensibly
1634         if (have_mm2 && _mem2->is_top())  _mem2 = _mm2->base_memory();
1635         return true;
1636       } else if (have_mm2 && !is_empty2()) {
1637         return true;   // is_empty() == true
1638       }
1639     }
1640     return false;
1641   }
1642 };
1643 
1644 // cachewb node for guaranteeing writeback of the cache line at a
1645 // given address to (non-volatile) RAM
1646 class CacheWBNode : public Node {
1647 public:
1648   CacheWBNode(Node *ctrl, Node *mem, Node *addr) : Node(ctrl, mem, addr) {}
1649   virtual int Opcode() const;
1650   virtual uint ideal_reg() const { return NotAMachineReg; }
1651   virtual uint match_edge(uint idx) const { return (idx == 2); }
1652   virtual const TypePtr *adr_type() const { return TypePtr::BOTTOM; }
1653   virtual const Type *bottom_type() const { return Type::MEMORY; }
1654 };
1655 
1656 // cachewb pre sync node for ensuring that writebacks are serialised
1657 // relative to preceding or following stores
1658 class CacheWBPreSyncNode : public Node {
1659 public:
1660   CacheWBPreSyncNode(Node *ctrl, Node *mem) : Node(ctrl, mem) {}
1661   virtual int Opcode() const;
1662   virtual uint ideal_reg() const { return NotAMachineReg; }
1663   virtual uint match_edge(uint idx) const { return false; }
1664   virtual const TypePtr *adr_type() const { return TypePtr::BOTTOM; }
1665   virtual const Type *bottom_type() const { return Type::MEMORY; }
1666 };
1667 
1668 // cachewb pre sync node for ensuring that writebacks are serialised
1669 // relative to preceding or following stores
1670 class CacheWBPostSyncNode : public Node {
1671 public:
1672   CacheWBPostSyncNode(Node *ctrl, Node *mem) : Node(ctrl, mem) {}
1673   virtual int Opcode() const;
1674   virtual uint ideal_reg() const { return NotAMachineReg; }
1675   virtual uint match_edge(uint idx) const { return false; }
1676   virtual const TypePtr *adr_type() const { return TypePtr::BOTTOM; }
1677   virtual const Type *bottom_type() const { return Type::MEMORY; }
1678 };
1679 
1680 //------------------------------Prefetch---------------------------------------
1681 
1682 // Allocation prefetch which may fault, TLAB size have to be adjusted.
1683 class PrefetchAllocationNode : public Node {
1684 public:
1685   PrefetchAllocationNode(Node *mem, Node *adr) : Node(nullptr,mem,adr) {}
1686   virtual int Opcode() const;
1687   virtual uint ideal_reg() const { return NotAMachineReg; }
1688   virtual uint match_edge(uint idx) const { return idx==2; }
1689   virtual const Type *bottom_type() const { return ( AllocatePrefetchStyle == 3 ) ? Type::MEMORY : Type::ABIO; }
1690 };
1691 
1692 #endif // SHARE_OPTO_MEMNODE_HPP