jdk8-mips64-public/hotspot: src/share/vm/opto/memnode.hpp@c1c199dde5c9 (annotated)

src/share/vm/opto/memnode.hpp@c1c199dde5c9 (annotated)

src/share/vm/opto/memnode.hpp

Wed, 03 Jun 2015 14:22:57 +0200

author: roland
date: Wed, 03 Jun 2015 14:22:57 +0200
changeset 7859: c1c199dde5c9
parent 7858: 55d07ec5bde4
child 7994: 04ff2f6cd0eb
child 8653: 0ffee573412b
permissions: -rw-r--r--

8077504: Unsafe load can loose control dependency and cause crash
Summary: Node::depends_only_on_test() should return false for Unsafe loads
Reviewed-by: kvn, adinn

 /*
  * Copyright (c) 1997, 2013, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
  * under the terms of the GNU General Public License version 2 only, as
  * published by the Free Software Foundation.
  *
  * This code is distributed in the hope that it will be useful, but WITHOUT
  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  * version 2 for more details (a copy is included in the LICENSE file that
  * accompanied this code).
  *
  * You should have received a copy of the GNU General Public License version
  * 2 along with this work; if not, write to the Free Software Foundation,
  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  *
  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  * or visit www.oracle.com if you need additional information or have any
  * questions.
  *
  */
 #ifndef SHARE_VM_OPTO_MEMNODE_HPP
 #define SHARE_VM_OPTO_MEMNODE_HPP
 #include "opto/multnode.hpp"
 #include "opto/node.hpp"
 #include "opto/opcodes.hpp"
 #include "opto/type.hpp"
 // Portions of code courtesy of Clifford Click
 class MultiNode;
 class PhaseCCP;
 class PhaseTransform;
 //------------------------------MemNode----------------------------------------
 // Load or Store, possibly throwing a NULL pointer exception
 class MemNode : public Node {
 protected:
 #ifdef ASSERT
   const TypePtr* _adr_type;     // What kind of memory is being addressed?
 #endif
   virtual uint size_of() const; // Size is bigger (ASSERT only)
 public:
   enum { Control,               // When is it safe to do this load?
          Memory,                // Chunk of memory is being loaded from
          Address,               // Actually address, derived from base
          ValueIn,               // Value to store
          OopStore               // Preceeding oop store, only in StoreCM
   };
   typedef enum { unordered = 0,
                  acquire,       // Load has to acquire or be succeeded by MemBarAcquire.
                  release        // Store has to release or be preceded by MemBarRelease.
   } MemOrd;
 protected:
   MemNode( Node *c0, Node *c1, Node *c2, const TypePtr* at )
     : Node(c0,c1,c2   ) {
     init_class_id(Class_Mem);
     debug_only(_adr_type=at; adr_type();)
   }
   MemNode( Node *c0, Node *c1, Node *c2, const TypePtr* at, Node *c3 )
     : Node(c0,c1,c2,c3) {
     init_class_id(Class_Mem);
     debug_only(_adr_type=at; adr_type();)
   }
   MemNode( Node *c0, Node *c1, Node *c2, const TypePtr* at, Node *c3, Node *c4)
     : Node(c0,c1,c2,c3,c4) {
     init_class_id(Class_Mem);
     debug_only(_adr_type=at; adr_type();)
   }
 public:
   // Helpers for the optimizer.  Documented in memnode.cpp.
   static bool detect_ptr_independence(Node* p1, AllocateNode* a1,
                                       Node* p2, AllocateNode* a2,
                                       PhaseTransform* phase);
   static bool adr_phi_is_loop_invariant(Node* adr_phi, Node* cast);
   static Node *optimize_simple_memory_chain(Node *mchain, const TypeOopPtr *t_oop, Node *load, PhaseGVN *phase);
   static Node *optimize_memory_chain(Node *mchain, const TypePtr *t_adr, Node *load, PhaseGVN *phase);
   // This one should probably be a phase-specific function:
   static bool all_controls_dominate(Node* dom, Node* sub);
   // Find any cast-away of null-ness and keep its control.
   static  Node *Ideal_common_DU_postCCP( PhaseCCP *ccp, Node* n, Node* adr );
   virtual Node *Ideal_DU_postCCP( PhaseCCP *ccp );
   virtual const class TypePtr *adr_type() const;  // returns bottom_type of address
   // Shared code for Ideal methods:
   Node *Ideal_common(PhaseGVN *phase, bool can_reshape);  // Return -1 for short-circuit NULL.
   // Helper function for adr_type() implementations.
   static const TypePtr* calculate_adr_type(const Type* t, const TypePtr* cross_check = NULL);
   // Raw access function, to allow copying of adr_type efficiently in
   // product builds and retain the debug info for debug builds.
   const TypePtr *raw_adr_type() const {
 #ifdef ASSERT
     return _adr_type;
 #else
     return 0;
 #endif
   }
   // Map a load or store opcode to its corresponding store opcode.
   // (Return -1 if unknown.)
   virtual int store_Opcode() const { return -1; }
   // What is the type of the value in memory?  (T_VOID mean "unspecified".)
   virtual BasicType memory_type() const = 0;
   virtual int memory_size() const {
 #ifdef ASSERT
     return type2aelembytes(memory_type(), true);
 #else
     return type2aelembytes(memory_type());
 #endif
   }
   // Search through memory states which precede this node (load or store).
   // Look for an exact match for the address, with no intervening
   // aliased stores.
   Node* find_previous_store(PhaseTransform* phase);
   // Can this node (load or store) accurately see a stored value in
   // the given memory state?  (The state may or may not be in(Memory).)
   Node* can_see_stored_value(Node* st, PhaseTransform* phase) const;
 #ifndef PRODUCT
   static void dump_adr_type(const Node* mem, const TypePtr* adr_type, outputStream *st);
   virtual void dump_spec(outputStream *st) const;
 #endif
 };
 //------------------------------LoadNode---------------------------------------
 // Load value; requires Memory and Address
 class LoadNode : public MemNode {
 public:
   // Some loads (from unsafe) should be pinned: they don't depend only
   // on the dominating test.  The boolean field _depends_only_on_test
   // below records whether that node depends only on the dominating
   // test.
   // Methods used to build LoadNodes pass an argument of type enum
   // ControlDependency instead of a boolean because those methods
   // typically have multiple boolean parameters with default values:
   // passing the wrong boolean to one of these parameters by mistake
   // goes easily unnoticed. Using an enum, the compiler can check that
   // the type of a value and the type of the parameter match.
   enum ControlDependency {
     Pinned,
     DependsOnlyOnTest
   };
 private:
   // LoadNode::hash() doesn't take the _depends_only_on_test field
   // into account: If the graph already has a non-pinned LoadNode and
   // we add a pinned LoadNode with the same inputs, it's safe for GVN
   // to replace the pinned LoadNode with the non-pinned LoadNode,
   // otherwise it wouldn't be safe to have a non pinned LoadNode with
   // those inputs in the first place. If the graph already has a
   // pinned LoadNode and we add a non pinned LoadNode with the same
   // inputs, it's safe (but suboptimal) for GVN to replace the
   // non-pinned LoadNode by the pinned LoadNode.
   bool _depends_only_on_test;
   // On platforms with weak memory ordering (e.g., PPC, Ia64) we distinguish
   // loads that can be reordered, and such requiring acquire semantics to
   // adhere to the Java specification.  The required behaviour is stored in
   // this field.
   const MemOrd _mo;
 protected:
   virtual uint cmp(const Node &n) const;
   virtual uint size_of() const; // Size is bigger
   // Should LoadNode::Ideal() attempt to remove control edges?
   virtual bool can_remove_control() const;
   const Type* const _type;      // What kind of value is loaded?
 public:
   LoadNode(Node *c, Node *mem, Node *adr, const TypePtr* at, const Type *rt, MemOrd mo, ControlDependency control_dependency)
     : MemNode(c,mem,adr,at), _type(rt), _mo(mo), _depends_only_on_test(control_dependency == DependsOnlyOnTest) {
     init_class_id(Class_Load);
   }
   inline bool is_unordered() const { return !is_acquire(); }
   inline bool is_acquire() const {
     assert(_mo == unordered || _mo == acquire, "unexpected");
     return _mo == acquire;
   }
   // Polymorphic factory method:
    static Node* make(PhaseGVN& gvn, Node *c, Node *mem, Node *adr,
                      const TypePtr* at, const Type *rt, BasicType bt,
                      MemOrd mo, ControlDependency control_dependency = DependsOnlyOnTest);
   virtual uint hash()   const;  // Check the type
   // Handle algebraic identities here.  If we have an identity, return the Node
   // we are equivalent to.  We look for Load of a Store.
   virtual Node *Identity( PhaseTransform *phase );
   // If the load is from Field memory and the pointer is non-null, it might be possible to
   // zero out the control input.
   // If the offset is constant and the base is an object allocation,
   // try to hook me up to the exact initializing store.
   virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
   // Split instance field load through Phi.
   Node* split_through_phi(PhaseGVN *phase);
   // Recover original value from boxed values
   Node *eliminate_autobox(PhaseGVN *phase);
   // Compute a new Type for this node.  Basically we just do the pre-check,
   // then call the virtual add() to set the type.
   virtual const Type *Value( PhaseTransform *phase ) const;
   // Common methods for LoadKlass and LoadNKlass nodes.
   const Type *klass_value_common( PhaseTransform *phase ) const;
   Node *klass_identity_common( PhaseTransform *phase );
   virtual uint ideal_reg() const;
   virtual const Type *bottom_type() const;
   // Following method is copied from TypeNode:
   void set_type(const Type* t) {
     assert(t != NULL, "sanity");
     debug_only(uint check_hash = (VerifyHashTableKeys && _hash_lock) ? hash() : NO_HASH);
     *(const Type**)&_type = t;   // cast away const-ness
     // If this node is in the hash table, make sure it doesn't need a rehash.
     assert(check_hash == NO_HASH || check_hash == hash(), "type change must preserve hash code");
   }
   const Type* type() const { assert(_type != NULL, "sanity"); return _type; };
   // Do not match memory edge
   virtual uint match_edge(uint idx) const;
   // Map a load opcode to its corresponding store opcode.
   virtual int store_Opcode() const = 0;
   // Check if the load's memory input is a Phi node with the same control.
   bool is_instance_field_load_with_local_phi(Node* ctrl);
 #ifndef PRODUCT
   virtual void dump_spec(outputStream *st) const;
 #endif
 #ifdef ASSERT
   // Helper function to allow a raw load without control edge for some cases
   static bool is_immutable_value(Node* adr);
 #endif
 protected:
   const Type* load_array_final_field(const TypeKlassPtr *tkls,
                                      ciKlass* klass) const;
   // depends_only_on_test is almost always true, and needs to be almost always
   // true to enable key hoisting & commoning optimizations.  However, for the
   // special case of RawPtr loads from TLS top & end, and other loads performed by
   // GC barriers, the control edge carries the dependence preventing hoisting past
   // a Safepoint instead of the memory edge.  (An unfortunate consequence of having
   // Safepoints not set Raw Memory; itself an unfortunate consequence of having Nodes
   // which produce results (new raw memory state) inside of loops preventing all
   // manner of other optimizations).  Basically, it's ugly but so is the alternative.
   // See comment in macro.cpp, around line 125 expand_allocate_common().
   virtual bool depends_only_on_test() const { return adr_type() != TypeRawPtr::BOTTOM && _depends_only_on_test; }
 };
 //------------------------------LoadBNode--------------------------------------
 // Load a byte (8bits signed) from memory
 class LoadBNode : public LoadNode {
 public:
   LoadBNode(Node *c, Node *mem, Node *adr, const TypePtr* at, const TypeInt *ti, MemOrd mo, ControlDependency control_dependency = DependsOnlyOnTest)
     : LoadNode(c, mem, adr, at, ti, mo, control_dependency) {}
   virtual int Opcode() const;
   virtual uint ideal_reg() const { return Op_RegI; }
   virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
   virtual const Type *Value(PhaseTransform *phase) const;
   virtual int store_Opcode() const { return Op_StoreB; }
   virtual BasicType memory_type() const { return T_BYTE; }
 };
 //------------------------------LoadUBNode-------------------------------------
 // Load a unsigned byte (8bits unsigned) from memory
 class LoadUBNode : public LoadNode {
 public:
   LoadUBNode(Node* c, Node* mem, Node* adr, const TypePtr* at, const TypeInt* ti, MemOrd mo, ControlDependency control_dependency = DependsOnlyOnTest)
     : LoadNode(c, mem, adr, at, ti, mo, control_dependency) {}
   virtual int Opcode() const;
   virtual uint ideal_reg() const { return Op_RegI; }
   virtual Node* Ideal(PhaseGVN *phase, bool can_reshape);
   virtual const Type *Value(PhaseTransform *phase) const;
   virtual int store_Opcode() const { return Op_StoreB; }
   virtual BasicType memory_type() const { return T_BYTE; }
 };
 //------------------------------LoadUSNode-------------------------------------
 // Load an unsigned short/char (16bits unsigned) from memory
 class LoadUSNode : public LoadNode {
 public:
   LoadUSNode(Node *c, Node *mem, Node *adr, const TypePtr* at, const TypeInt *ti, MemOrd mo, ControlDependency control_dependency = DependsOnlyOnTest)
     : LoadNode(c, mem, adr, at, ti, mo, control_dependency) {}
   virtual int Opcode() const;
   virtual uint ideal_reg() const { return Op_RegI; }
   virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
   virtual const Type *Value(PhaseTransform *phase) const;
   virtual int store_Opcode() const { return Op_StoreC; }
   virtual BasicType memory_type() const { return T_CHAR; }
 };
 //------------------------------LoadSNode--------------------------------------
 // Load a short (16bits signed) from memory
 class LoadSNode : public LoadNode {
 public:
   LoadSNode(Node *c, Node *mem, Node *adr, const TypePtr* at, const TypeInt *ti, MemOrd mo, ControlDependency control_dependency = DependsOnlyOnTest)
     : LoadNode(c, mem, adr, at, ti, mo, control_dependency) {}
   virtual int Opcode() const;
   virtual uint ideal_reg() const { return Op_RegI; }
   virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
   virtual const Type *Value(PhaseTransform *phase) const;
   virtual int store_Opcode() const { return Op_StoreC; }
   virtual BasicType memory_type() const { return T_SHORT; }
 };
 //------------------------------LoadINode--------------------------------------
 // Load an integer from memory
 class LoadINode : public LoadNode {
 public:
   LoadINode(Node *c, Node *mem, Node *adr, const TypePtr* at, const TypeInt *ti, MemOrd mo, ControlDependency control_dependency = DependsOnlyOnTest)
     : LoadNode(c, mem, adr, at, ti, mo, control_dependency) {}
   virtual int Opcode() const;
   virtual uint ideal_reg() const { return Op_RegI; }
   virtual int store_Opcode() const { return Op_StoreI; }
   virtual BasicType memory_type() const { return T_INT; }
 };
 //------------------------------LoadRangeNode----------------------------------
 // Load an array length from the array
 class LoadRangeNode : public LoadINode {
 public:
   LoadRangeNode(Node *c, Node *mem, Node *adr, const TypeInt *ti = TypeInt::POS)
     : LoadINode(c, mem, adr, TypeAryPtr::RANGE, ti, MemNode::unordered) {}
   virtual int Opcode() const;
   virtual const Type *Value( PhaseTransform *phase ) const;
   virtual Node *Identity( PhaseTransform *phase );
   virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
 };
 //------------------------------LoadLNode--------------------------------------
 // Load a long from memory
 class LoadLNode : public LoadNode {
   virtual uint hash() const { return LoadNode::hash() + _require_atomic_access; }
   virtual uint cmp( const Node &n ) const {
     return _require_atomic_access == ((LoadLNode&)n)._require_atomic_access
       && LoadNode::cmp(n);
   }
   virtual uint size_of() const { return sizeof(*this); }
   const bool _require_atomic_access;  // is piecewise load forbidden?
 public:
   LoadLNode(Node *c, Node *mem, Node *adr, const TypePtr* at, const TypeLong *tl,
             MemOrd mo, ControlDependency control_dependency = DependsOnlyOnTest, bool require_atomic_access = false)
     : LoadNode(c, mem, adr, at, tl, mo, control_dependency), _require_atomic_access(require_atomic_access) {}
   virtual int Opcode() const;
   virtual uint ideal_reg() const { return Op_RegL; }
   virtual int store_Opcode() const { return Op_StoreL; }
   virtual BasicType memory_type() const { return T_LONG; }
   bool require_atomic_access() const { return _require_atomic_access; }
   static LoadLNode* make_atomic(Compile *C, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type,
                                 const Type* rt, MemOrd mo, ControlDependency control_dependency = DependsOnlyOnTest);
 #ifndef PRODUCT
   virtual void dump_spec(outputStream *st) const {
     LoadNode::dump_spec(st);
     if (_require_atomic_access)  st->print(" Atomic!");
   }
 #endif
 };
 //------------------------------LoadL_unalignedNode----------------------------
 // Load a long from unaligned memory
 class LoadL_unalignedNode : public LoadLNode {
 public:
   LoadL_unalignedNode(Node *c, Node *mem, Node *adr, const TypePtr* at, MemOrd mo, ControlDependency control_dependency = DependsOnlyOnTest)
     : LoadLNode(c, mem, adr, at, TypeLong::LONG, mo, control_dependency) {}
   virtual int Opcode() const;
 };
 //------------------------------LoadFNode--------------------------------------
 // Load a float (64 bits) from memory
 class LoadFNode : public LoadNode {
 public:
   LoadFNode(Node *c, Node *mem, Node *adr, const TypePtr* at, const Type *t, MemOrd mo, ControlDependency control_dependency = DependsOnlyOnTest)
     : LoadNode(c, mem, adr, at, t, mo, control_dependency) {}
   virtual int Opcode() const;
   virtual uint ideal_reg() const { return Op_RegF; }
   virtual int store_Opcode() const { return Op_StoreF; }
   virtual BasicType memory_type() const { return T_FLOAT; }
 };
 //------------------------------LoadDNode--------------------------------------
 // Load a double (64 bits) from memory
 class LoadDNode : public LoadNode {
   virtual uint hash() const { return LoadNode::hash() + _require_atomic_access; }
   virtual uint cmp( const Node &n ) const {
     return _require_atomic_access == ((LoadDNode&)n)._require_atomic_access
       && LoadNode::cmp(n);
   }
   virtual uint size_of() const { return sizeof(*this); }
   const bool _require_atomic_access;  // is piecewise load forbidden?
 public:
   LoadDNode(Node *c, Node *mem, Node *adr, const TypePtr* at, const Type *t,
             MemOrd mo, ControlDependency control_dependency = DependsOnlyOnTest, bool require_atomic_access = false)
     : LoadNode(c, mem, adr, at, t, mo, control_dependency), _require_atomic_access(require_atomic_access) {}
   virtual int Opcode() const;
   virtual uint ideal_reg() const { return Op_RegD; }
   virtual int store_Opcode() const { return Op_StoreD; }
   virtual BasicType memory_type() const { return T_DOUBLE; }
   bool require_atomic_access() const { return _require_atomic_access; }
   static LoadDNode* make_atomic(Compile *C, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type,
                                 const Type* rt, MemOrd mo, ControlDependency control_dependency = DependsOnlyOnTest);
 #ifndef PRODUCT
   virtual void dump_spec(outputStream *st) const {
     LoadNode::dump_spec(st);
     if (_require_atomic_access)  st->print(" Atomic!");
   }
 #endif
 };
 //------------------------------LoadD_unalignedNode----------------------------
 // Load a double from unaligned memory
 class LoadD_unalignedNode : public LoadDNode {
 public:
   LoadD_unalignedNode(Node *c, Node *mem, Node *adr, const TypePtr* at, MemOrd mo, ControlDependency control_dependency = DependsOnlyOnTest)
     : LoadDNode(c, mem, adr, at, Type::DOUBLE, mo, control_dependency) {}
   virtual int Opcode() const;
 };
 //------------------------------LoadPNode--------------------------------------
 // Load a pointer from memory (either object or array)
 class LoadPNode : public LoadNode {
 public:
   LoadPNode(Node *c, Node *mem, Node *adr, const TypePtr *at, const TypePtr* t, MemOrd mo, ControlDependency control_dependency = DependsOnlyOnTest)
     : LoadNode(c, mem, adr, at, t, mo, control_dependency) {}
   virtual int Opcode() const;
   virtual uint ideal_reg() const { return Op_RegP; }
   virtual int store_Opcode() const { return Op_StoreP; }
   virtual BasicType memory_type() const { return T_ADDRESS; }
 };
 //------------------------------LoadNNode--------------------------------------
 // Load a narrow oop from memory (either object or array)
 class LoadNNode : public LoadNode {
 public:
   LoadNNode(Node *c, Node *mem, Node *adr, const TypePtr *at, const Type* t, MemOrd mo, ControlDependency control_dependency = DependsOnlyOnTest)
     : LoadNode(c, mem, adr, at, t, mo, control_dependency) {}
   virtual int Opcode() const;
   virtual uint ideal_reg() const { return Op_RegN; }
   virtual int store_Opcode() const { return Op_StoreN; }
   virtual BasicType memory_type() const { return T_NARROWOOP; }
 };
 //------------------------------LoadKlassNode----------------------------------
 // Load a Klass from an object
 class LoadKlassNode : public LoadPNode {
 protected:
   // In most cases, LoadKlassNode does not have the control input set. If the control
   // input is set, it must not be removed (by LoadNode::Ideal()).
   virtual bool can_remove_control() const;
 public:
   LoadKlassNode(Node *c, Node *mem, Node *adr, const TypePtr *at, const TypeKlassPtr *tk, MemOrd mo)
     : LoadPNode(c, mem, adr, at, tk, mo) {}
   virtual int Opcode() const;
   virtual const Type *Value( PhaseTransform *phase ) const;
   virtual Node *Identity( PhaseTransform *phase );
   virtual bool depends_only_on_test() const { return true; }
   // Polymorphic factory method:
   static Node* make(PhaseGVN& gvn, Node* ctl, Node* mem, Node* adr, const TypePtr* at,
                     const TypeKlassPtr* tk = TypeKlassPtr::OBJECT);
 };
 //------------------------------LoadNKlassNode---------------------------------
 // Load a narrow Klass from an object.
 class LoadNKlassNode : public LoadNNode {
 public:
   LoadNKlassNode(Node *c, Node *mem, Node *adr, const TypePtr *at, const TypeNarrowKlass *tk, MemOrd mo)
     : LoadNNode(c, mem, adr, at, tk, mo) {}
   virtual int Opcode() const;
   virtual uint ideal_reg() const { return Op_RegN; }
   virtual int store_Opcode() const { return Op_StoreNKlass; }
   virtual BasicType memory_type() const { return T_NARROWKLASS; }
   virtual const Type *Value( PhaseTransform *phase ) const;
   virtual Node *Identity( PhaseTransform *phase );
   virtual bool depends_only_on_test() const { return true; }
 };
 //------------------------------StoreNode--------------------------------------
 // Store value; requires Store, Address and Value
 class StoreNode : public MemNode {
 private:
   // On platforms with weak memory ordering (e.g., PPC, Ia64) we distinguish
   // stores that can be reordered, and such requiring release semantics to
   // adhere to the Java specification.  The required behaviour is stored in
   // this field.
   const MemOrd _mo;
   // Needed for proper cloning.
   virtual uint size_of() const { return sizeof(*this); }
 protected:
   virtual uint cmp( const Node &n ) const;
   virtual bool depends_only_on_test() const { return false; }
   Node *Ideal_masked_input       (PhaseGVN *phase, uint mask);
   Node *Ideal_sign_extended_input(PhaseGVN *phase, int  num_bits);
 public:
   // We must ensure that stores of object references will be visible
   // only after the object's initialization. So the callers of this
   // procedure must indicate that the store requires `release'
   // semantics, if the stored value is an object reference that might
   // point to a new object and may become externally visible.
   StoreNode(Node *c, Node *mem, Node *adr, const TypePtr* at, Node *val, MemOrd mo)
     : MemNode(c, mem, adr, at, val), _mo(mo) {
     init_class_id(Class_Store);
   }
   StoreNode(Node *c, Node *mem, Node *adr, const TypePtr* at, Node *val, Node *oop_store, MemOrd mo)
     : MemNode(c, mem, adr, at, val, oop_store), _mo(mo) {
     init_class_id(Class_Store);
   }
   inline bool is_unordered() const { return !is_release(); }
   inline bool is_release() const {
     assert((_mo == unordered || _mo == release), "unexpected");
     return _mo == release;
   }
   // Conservatively release stores of object references in order to
   // ensure visibility of object initialization.
   static inline MemOrd release_if_reference(const BasicType t) {
     const MemOrd mo = (t == T_ARRAY ||
                        t == T_ADDRESS || // Might be the address of an object reference (`boxing').
                        t == T_OBJECT) ? release : unordered;
     return mo;
   }
   // Polymorphic factory method
   //
   // We must ensure that stores of object references will be visible
   // only after the object's initialization. So the callers of this
   // procedure must indicate that the store requires `release'
   // semantics, if the stored value is an object reference that might
   // point to a new object and may become externally visible.
   static StoreNode* make(PhaseGVN& gvn, Node *c, Node *mem, Node *adr,
                          const TypePtr* at, Node *val, BasicType bt, MemOrd mo);
   virtual uint hash() const;    // Check the type
   // If the store is to Field memory and the pointer is non-null, we can
   // zero out the control input.
   virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
   // Compute a new Type for this node.  Basically we just do the pre-check,
   // then call the virtual add() to set the type.
   virtual const Type *Value( PhaseTransform *phase ) const;
   // Check for identity function on memory (Load then Store at same address)
   virtual Node *Identity( PhaseTransform *phase );
   // Do not match memory edge
   virtual uint match_edge(uint idx) const;
   virtual const Type *bottom_type() const;  // returns Type::MEMORY
   // Map a store opcode to its corresponding own opcode, trivially.
   virtual int store_Opcode() const { return Opcode(); }
   // have all possible loads of the value stored been optimized away?
   bool value_never_loaded(PhaseTransform *phase) const;
 };
 //------------------------------StoreBNode-------------------------------------
 // Store byte to memory
 class StoreBNode : public StoreNode {
 public:
   StoreBNode(Node *c, Node *mem, Node *adr, const TypePtr* at, Node *val, MemOrd mo)
     : StoreNode(c, mem, adr, at, val, mo) {}
   virtual int Opcode() const;
   virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
   virtual BasicType memory_type() const { return T_BYTE; }
 };
 //------------------------------StoreCNode-------------------------------------
 // Store char/short to memory
 class StoreCNode : public StoreNode {
 public:
   StoreCNode(Node *c, Node *mem, Node *adr, const TypePtr* at, Node *val, MemOrd mo)
     : StoreNode(c, mem, adr, at, val, mo) {}
   virtual int Opcode() const;
   virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
   virtual BasicType memory_type() const { return T_CHAR; }
 };
 //------------------------------StoreINode-------------------------------------
 // Store int to memory
 class StoreINode : public StoreNode {
 public:
   StoreINode(Node *c, Node *mem, Node *adr, const TypePtr* at, Node *val, MemOrd mo)
     : StoreNode(c, mem, adr, at, val, mo) {}
   virtual int Opcode() const;
   virtual BasicType memory_type() const { return T_INT; }
 };
 //------------------------------StoreLNode-------------------------------------
 // Store long to memory
 class StoreLNode : public StoreNode {
   virtual uint hash() const { return StoreNode::hash() + _require_atomic_access; }
   virtual uint cmp( const Node &n ) const {
     return _require_atomic_access == ((StoreLNode&)n)._require_atomic_access
       && StoreNode::cmp(n);
   }
   virtual uint size_of() const { return sizeof(*this); }
   const bool _require_atomic_access;  // is piecewise store forbidden?
 public:
   StoreLNode(Node *c, Node *mem, Node *adr, const TypePtr* at, Node *val, MemOrd mo, bool require_atomic_access = false)
     : StoreNode(c, mem, adr, at, val, mo), _require_atomic_access(require_atomic_access) {}
   virtual int Opcode() const;
   virtual BasicType memory_type() const { return T_LONG; }
   bool require_atomic_access() const { return _require_atomic_access; }
   static StoreLNode* make_atomic(Compile *C, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, MemOrd mo);
 #ifndef PRODUCT
   virtual void dump_spec(outputStream *st) const {
     StoreNode::dump_spec(st);
     if (_require_atomic_access)  st->print(" Atomic!");
   }
 #endif
 };
 //------------------------------StoreFNode-------------------------------------
 // Store float to memory
 class StoreFNode : public StoreNode {
 public:
   StoreFNode(Node *c, Node *mem, Node *adr, const TypePtr* at, Node *val, MemOrd mo)
     : StoreNode(c, mem, adr, at, val, mo) {}
   virtual int Opcode() const;
   virtual BasicType memory_type() const { return T_FLOAT; }
 };
 //------------------------------StoreDNode-------------------------------------
 // Store double to memory
 class StoreDNode : public StoreNode {
   virtual uint hash() const { return StoreNode::hash() + _require_atomic_access; }
   virtual uint cmp( const Node &n ) const {
     return _require_atomic_access == ((StoreDNode&)n)._require_atomic_access
       && StoreNode::cmp(n);
   }
   virtual uint size_of() const { return sizeof(*this); }
   const bool _require_atomic_access;  // is piecewise store forbidden?
 public:
   StoreDNode(Node *c, Node *mem, Node *adr, const TypePtr* at, Node *val,
              MemOrd mo, bool require_atomic_access = false)
     : StoreNode(c, mem, adr, at, val, mo), _require_atomic_access(require_atomic_access) {}
   virtual int Opcode() const;
   virtual BasicType memory_type() const { return T_DOUBLE; }
   bool require_atomic_access() const { return _require_atomic_access; }
   static StoreDNode* make_atomic(Compile *C, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, MemOrd mo);
 #ifndef PRODUCT
   virtual void dump_spec(outputStream *st) const {
     StoreNode::dump_spec(st);
     if (_require_atomic_access)  st->print(" Atomic!");
   }
 #endif
 };
 //------------------------------StorePNode-------------------------------------
 // Store pointer to memory
 class StorePNode : public StoreNode {
 public:
   StorePNode(Node *c, Node *mem, Node *adr, const TypePtr* at, Node *val, MemOrd mo)
     : StoreNode(c, mem, adr, at, val, mo) {}
   virtual int Opcode() const;
   virtual BasicType memory_type() const { return T_ADDRESS; }
 };
 //------------------------------StoreNNode-------------------------------------
 // Store narrow oop to memory
 class StoreNNode : public StoreNode {
 public:
   StoreNNode(Node *c, Node *mem, Node *adr, const TypePtr* at, Node *val, MemOrd mo)
     : StoreNode(c, mem, adr, at, val, mo) {}
   virtual int Opcode() const;
   virtual BasicType memory_type() const { return T_NARROWOOP; }
 };
 //------------------------------StoreNKlassNode--------------------------------------
 // Store narrow klass to memory
 class StoreNKlassNode : public StoreNNode {
 public:
   StoreNKlassNode(Node *c, Node *mem, Node *adr, const TypePtr* at, Node *val, MemOrd mo)
     : StoreNNode(c, mem, adr, at, val, mo) {}
   virtual int Opcode() const;
   virtual BasicType memory_type() const { return T_NARROWKLASS; }
 };
 //------------------------------StoreCMNode-----------------------------------
 // Store card-mark byte to memory for CM
 // The last StoreCM before a SafePoint must be preserved and occur after its "oop" store
 // Preceeding equivalent StoreCMs may be eliminated.
 class StoreCMNode : public StoreNode {
  private:
   virtual uint hash() const { return StoreNode::hash() + _oop_alias_idx; }
   virtual uint cmp( const Node &n ) const {
     return _oop_alias_idx == ((StoreCMNode&)n)._oop_alias_idx
       && StoreNode::cmp(n);
   }
   virtual uint size_of() const { return sizeof(*this); }
   int _oop_alias_idx;   // The alias_idx of OopStore
 public:
   StoreCMNode( Node *c, Node *mem, Node *adr, const TypePtr* at, Node *val, Node *oop_store, int oop_alias_idx ) :
     StoreNode(c, mem, adr, at, val, oop_store, MemNode::release),
     _oop_alias_idx(oop_alias_idx) {
     assert(_oop_alias_idx >= Compile::AliasIdxRaw ||
            _oop_alias_idx == Compile::AliasIdxBot && Compile::current()->AliasLevel() == 0,
            "bad oop alias idx");
   }
   virtual int Opcode() const;
   virtual Node *Identity( PhaseTransform *phase );
   virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
   virtual const Type *Value( PhaseTransform *phase ) const;
   virtual BasicType memory_type() const { return T_VOID; } // unspecific
   int oop_alias_idx() const { return _oop_alias_idx; }
 };
 //------------------------------LoadPLockedNode---------------------------------
 // Load-locked a pointer from memory (either object or array).
 // On Sparc & Intel this is implemented as a normal pointer load.
 // On PowerPC and friends it's a real load-locked.
 class LoadPLockedNode : public LoadPNode {
 public:
   LoadPLockedNode(Node *c, Node *mem, Node *adr, MemOrd mo)
     : LoadPNode(c, mem, adr, TypeRawPtr::BOTTOM, TypeRawPtr::BOTTOM, mo) {}
   virtual int Opcode() const;
   virtual int store_Opcode() const { return Op_StorePConditional; }
   virtual bool depends_only_on_test() const { return true; }
 };
 //------------------------------SCMemProjNode---------------------------------------
 // This class defines a projection of the memory  state of a store conditional node.
 // These nodes return a value, but also update memory.
 class SCMemProjNode : public ProjNode {
 public:
   enum {SCMEMPROJCON = (uint)-2};
   SCMemProjNode( Node *src) : ProjNode( src, SCMEMPROJCON) { }
   virtual int Opcode() const;
   virtual bool      is_CFG() const  { return false; }
   virtual const Type *bottom_type() const {return Type::MEMORY;}
   virtual const TypePtr *adr_type() const { return in(0)->in(MemNode::Memory)->adr_type();}
   virtual uint ideal_reg() const { return 0;} // memory projections don't have a register
   virtual const Type *Value( PhaseTransform *phase ) const;
 #ifndef PRODUCT
   virtual void dump_spec(outputStream *st) const {};
 #endif
 };
 //------------------------------LoadStoreNode---------------------------
 // Note: is_Mem() method returns 'true' for this class.
 class LoadStoreNode : public Node {
 private:
   const Type* const _type;      // What kind of value is loaded?
   const TypePtr* _adr_type;     // What kind of memory is being addressed?
   virtual uint size_of() const; // Size is bigger
 public:
   LoadStoreNode( Node *c, Node *mem, Node *adr, Node *val, const TypePtr* at, const Type* rt, uint required );
   virtual bool depends_only_on_test() const { return false; }
   virtual uint match_edge(uint idx) const { return idx == MemNode::Address || idx == MemNode::ValueIn; }
   virtual const Type *bottom_type() const { return _type; }
   virtual uint ideal_reg() const;
   virtual const class TypePtr *adr_type() const { return _adr_type; }  // returns bottom_type of address
   bool result_not_used() const;
 };
 class LoadStoreConditionalNode : public LoadStoreNode {
 public:
   enum {
     ExpectedIn = MemNode::ValueIn+1 // One more input than MemNode
   };
   LoadStoreConditionalNode(Node *c, Node *mem, Node *adr, Node *val, Node *ex);
 };
 //------------------------------StorePConditionalNode---------------------------
 // Conditionally store pointer to memory, if no change since prior
 // load-locked.  Sets flags for success or failure of the store.
 class StorePConditionalNode : public LoadStoreConditionalNode {
 public:
   StorePConditionalNode( Node *c, Node *mem, Node *adr, Node *val, Node *ll ) : LoadStoreConditionalNode(c, mem, adr, val, ll) { }
   virtual int Opcode() const;
   // Produces flags
   virtual uint ideal_reg() const { return Op_RegFlags; }
 };
 //------------------------------StoreIConditionalNode---------------------------
 // Conditionally store int to memory, if no change since prior
 // load-locked.  Sets flags for success or failure of the store.
 class StoreIConditionalNode : public LoadStoreConditionalNode {
 public:
   StoreIConditionalNode( Node *c, Node *mem, Node *adr, Node *val, Node *ii ) : LoadStoreConditionalNode(c, mem, adr, val, ii) { }
   virtual int Opcode() const;
   // Produces flags
   virtual uint ideal_reg() const { return Op_RegFlags; }
 };
 //------------------------------StoreLConditionalNode---------------------------
 // Conditionally store long to memory, if no change since prior
 // load-locked.  Sets flags for success or failure of the store.
 class StoreLConditionalNode : public LoadStoreConditionalNode {
 public:
   StoreLConditionalNode( Node *c, Node *mem, Node *adr, Node *val, Node *ll ) : LoadStoreConditionalNode(c, mem, adr, val, ll) { }
   virtual int Opcode() const;
   // Produces flags
   virtual uint ideal_reg() const { return Op_RegFlags; }
 };
 //------------------------------CompareAndSwapLNode---------------------------
 class CompareAndSwapLNode : public LoadStoreConditionalNode {
 public:
   CompareAndSwapLNode( Node *c, Node *mem, Node *adr, Node *val, Node *ex) : LoadStoreConditionalNode(c, mem, adr, val, ex) { }
   virtual int Opcode() const;
 };
 //------------------------------CompareAndSwapINode---------------------------
 class CompareAndSwapINode : public LoadStoreConditionalNode {
 public:
   CompareAndSwapINode( Node *c, Node *mem, Node *adr, Node *val, Node *ex) : LoadStoreConditionalNode(c, mem, adr, val, ex) { }
   virtual int Opcode() const;
 };
 //------------------------------CompareAndSwapPNode---------------------------
 class CompareAndSwapPNode : public LoadStoreConditionalNode {
 public:
   CompareAndSwapPNode( Node *c, Node *mem, Node *adr, Node *val, Node *ex) : LoadStoreConditionalNode(c, mem, adr, val, ex) { }
   virtual int Opcode() const;
 };
 //------------------------------CompareAndSwapNNode---------------------------
 class CompareAndSwapNNode : public LoadStoreConditionalNode {
 public:
   CompareAndSwapNNode( Node *c, Node *mem, Node *adr, Node *val, Node *ex) : LoadStoreConditionalNode(c, mem, adr, val, ex) { }
   virtual int Opcode() const;
 };
 //------------------------------GetAndAddINode---------------------------
 class GetAndAddINode : public LoadStoreNode {
 public:
   GetAndAddINode( Node *c, Node *mem, Node *adr, Node *val, const TypePtr* at ) : LoadStoreNode(c, mem, adr, val, at, TypeInt::INT, 4) { }
   virtual int Opcode() const;
 };
 //------------------------------GetAndAddLNode---------------------------
 class GetAndAddLNode : public LoadStoreNode {
 public:
   GetAndAddLNode( Node *c, Node *mem, Node *adr, Node *val, const TypePtr* at ) : LoadStoreNode(c, mem, adr, val, at, TypeLong::LONG, 4) { }
   virtual int Opcode() const;
 };
 //------------------------------GetAndSetINode---------------------------
 class GetAndSetINode : public LoadStoreNode {
 public:
   GetAndSetINode( Node *c, Node *mem, Node *adr, Node *val, const TypePtr* at ) : LoadStoreNode(c, mem, adr, val, at, TypeInt::INT, 4) { }
   virtual int Opcode() const;
 };
 //------------------------------GetAndSetINode---------------------------
 class GetAndSetLNode : public LoadStoreNode {
 public:
   GetAndSetLNode( Node *c, Node *mem, Node *adr, Node *val, const TypePtr* at ) : LoadStoreNode(c, mem, adr, val, at, TypeLong::LONG, 4) { }
   virtual int Opcode() const;
 };
 //------------------------------GetAndSetPNode---------------------------
 class GetAndSetPNode : public LoadStoreNode {
 public:
   GetAndSetPNode( Node *c, Node *mem, Node *adr, Node *val, const TypePtr* at, const Type* t ) : LoadStoreNode(c, mem, adr, val, at, t, 4) { }
   virtual int Opcode() const;
 };
 //------------------------------GetAndSetNNode---------------------------
 class GetAndSetNNode : public LoadStoreNode {
 public:
   GetAndSetNNode( Node *c, Node *mem, Node *adr, Node *val, const TypePtr* at, const Type* t ) : LoadStoreNode(c, mem, adr, val, at, t, 4) { }
   virtual int Opcode() const;
 };
 //------------------------------ClearArray-------------------------------------
 class ClearArrayNode: public Node {
 public:
   ClearArrayNode( Node *ctrl, Node *arymem, Node *word_cnt, Node *base )
     : Node(ctrl,arymem,word_cnt,base) {
     init_class_id(Class_ClearArray);
   }
   virtual int         Opcode() const;
   virtual const Type *bottom_type() const { return Type::MEMORY; }
   // ClearArray modifies array elements, and so affects only the
   // array memory addressed by the bottom_type of its base address.
   virtual const class TypePtr *adr_type() const;
   virtual Node *Identity( PhaseTransform *phase );
   virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
   virtual uint match_edge(uint idx) const;
   // Clear the given area of an object or array.
   // The start offset must always be aligned mod BytesPerInt.
   // The end offset must always be aligned mod BytesPerLong.
   // Return the new memory.
   static Node* clear_memory(Node* control, Node* mem, Node* dest,
                             intptr_t start_offset,
                             intptr_t end_offset,
                             PhaseGVN* phase);
   static Node* clear_memory(Node* control, Node* mem, Node* dest,
                             intptr_t start_offset,
                             Node* end_offset,
                             PhaseGVN* phase);
   static Node* clear_memory(Node* control, Node* mem, Node* dest,
                             Node* start_offset,
                             Node* end_offset,
                             PhaseGVN* phase);
   // Return allocation input memory edge if it is different instance
   // or itself if it is the one we are looking for.
   static bool step_through(Node** np, uint instance_id, PhaseTransform* phase);
 };
 //------------------------------StrIntrinsic-------------------------------
 // Base class for Ideal nodes used in String instrinsic code.
 class StrIntrinsicNode: public Node {
 public:
   StrIntrinsicNode(Node* control, Node* char_array_mem,
                    Node* s1, Node* c1, Node* s2, Node* c2):
     Node(control, char_array_mem, s1, c1, s2, c2) {
   }
   StrIntrinsicNode(Node* control, Node* char_array_mem,
                    Node* s1, Node* s2, Node* c):
     Node(control, char_array_mem, s1, s2, c) {
   }
   StrIntrinsicNode(Node* control, Node* char_array_mem,
                    Node* s1, Node* s2):
     Node(control, char_array_mem, s1, s2) {
   }
   virtual bool depends_only_on_test() const { return false; }
   virtual const TypePtr* adr_type() const { return TypeAryPtr::CHARS; }
   virtual uint match_edge(uint idx) const;
   virtual uint ideal_reg() const { return Op_RegI; }
   virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
   virtual const Type *Value(PhaseTransform *phase) const;
 };
 //------------------------------StrComp-------------------------------------
 class StrCompNode: public StrIntrinsicNode {
 public:
   StrCompNode(Node* control, Node* char_array_mem,
               Node* s1, Node* c1, Node* s2, Node* c2):
     StrIntrinsicNode(control, char_array_mem, s1, c1, s2, c2) {};
   virtual int Opcode() const;
   virtual const Type* bottom_type() const { return TypeInt::INT; }
 };
 //------------------------------StrEquals-------------------------------------
 class StrEqualsNode: public StrIntrinsicNode {
 public:
   StrEqualsNode(Node* control, Node* char_array_mem,
                 Node* s1, Node* s2, Node* c):
     StrIntrinsicNode(control, char_array_mem, s1, s2, c) {};
   virtual int Opcode() const;
   virtual const Type* bottom_type() const { return TypeInt::BOOL; }
 };
 //------------------------------StrIndexOf-------------------------------------
 class StrIndexOfNode: public StrIntrinsicNode {
 public:
   StrIndexOfNode(Node* control, Node* char_array_mem,
               Node* s1, Node* c1, Node* s2, Node* c2):
     StrIntrinsicNode(control, char_array_mem, s1, c1, s2, c2) {};
   virtual int Opcode() const;
   virtual const Type* bottom_type() const { return TypeInt::INT; }
 };
 //------------------------------AryEq---------------------------------------
 class AryEqNode: public StrIntrinsicNode {
 public:
   AryEqNode(Node* control, Node* char_array_mem, Node* s1, Node* s2):
     StrIntrinsicNode(control, char_array_mem, s1, s2) {};
   virtual int Opcode() const;
   virtual const Type* bottom_type() const { return TypeInt::BOOL; }
 };
 //------------------------------EncodeISOArray--------------------------------
 // encode char[] to byte[] in ISO_8859_1
 class EncodeISOArrayNode: public Node {
 public:
   EncodeISOArrayNode(Node *control, Node* arymem, Node* s1, Node* s2, Node* c): Node(control, arymem, s1, s2, c) {};
   virtual int Opcode() const;
   virtual bool depends_only_on_test() const { return false; }
   virtual const Type* bottom_type() const { return TypeInt::INT; }
   virtual const TypePtr* adr_type() const { return TypePtr::BOTTOM; }
   virtual uint match_edge(uint idx) const;
   virtual uint ideal_reg() const { return Op_RegI; }
   virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
   virtual const Type *Value(PhaseTransform *phase) const;
 };
 //------------------------------MemBar-----------------------------------------
 // There are different flavors of Memory Barriers to match the Java Memory
 // Model.  Monitor-enter and volatile-load act as Aquires: no following ref
 // can be moved to before them.  We insert a MemBar-Acquire after a FastLock or
 // volatile-load.  Monitor-exit and volatile-store act as Release: no
 // preceding ref can be moved to after them.  We insert a MemBar-Release
 // before a FastUnlock or volatile-store.  All volatiles need to be
 // serialized, so we follow all volatile-stores with a MemBar-Volatile to
 // separate it from any following volatile-load.
 class MemBarNode: public MultiNode {
   virtual uint hash() const ;                  // { return NO_HASH; }
   virtual uint cmp( const Node &n ) const ;    // Always fail, except on self
   virtual uint size_of() const { return sizeof(*this); }
   // Memory type this node is serializing.  Usually either rawptr or bottom.
   const TypePtr* _adr_type;
 public:
   enum {
     Precedent = TypeFunc::Parms  // optional edge to force precedence
   };
   MemBarNode(Compile* C, int alias_idx, Node* precedent);
   virtual int Opcode() const = 0;
   virtual const class TypePtr *adr_type() const { return _adr_type; }
   virtual const Type *Value( PhaseTransform *phase ) const;
   virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
   virtual uint match_edge(uint idx) const { return 0; }
   virtual const Type *bottom_type() const { return TypeTuple::MEMBAR; }
   virtual Node *match( const ProjNode *proj, const Matcher *m );
   // Factory method.  Builds a wide or narrow membar.
   // Optional 'precedent' becomes an extra edge if not null.
   static MemBarNode* make(Compile* C, int opcode,
                           int alias_idx = Compile::AliasIdxBot,
                           Node* precedent = NULL);
 };
 // "Acquire" - no following ref can move before (but earlier refs can
 // follow, like an early Load stalled in cache).  Requires multi-cpu
 // visibility.  Inserted after a volatile load.
 class MemBarAcquireNode: public MemBarNode {
 public:
   MemBarAcquireNode(Compile* C, int alias_idx, Node* precedent)
     : MemBarNode(C, alias_idx, precedent) {}
   virtual int Opcode() const;
 };
 // "Acquire" - no following ref can move before (but earlier refs can
 // follow, like an early Load stalled in cache).  Requires multi-cpu
 // visibility.  Inserted independ of any load, as required
 // for intrinsic sun.misc.Unsafe.loadFence().
 class LoadFenceNode: public MemBarNode {
 public:
   LoadFenceNode(Compile* C, int alias_idx, Node* precedent)
     : MemBarNode(C, alias_idx, precedent) {}
   virtual int Opcode() const;
 };
 // "Release" - no earlier ref can move after (but later refs can move
 // up, like a speculative pipelined cache-hitting Load).  Requires
 // multi-cpu visibility.  Inserted before a volatile store.
 class MemBarReleaseNode: public MemBarNode {
 public:
   MemBarReleaseNode(Compile* C, int alias_idx, Node* precedent)
     : MemBarNode(C, alias_idx, precedent) {}
   virtual int Opcode() const;
 };
 // "Release" - no earlier ref can move after (but later refs can move
 // up, like a speculative pipelined cache-hitting Load).  Requires
 // multi-cpu visibility.  Inserted independent of any store, as required
 // for intrinsic sun.misc.Unsafe.storeFence().
 class StoreFenceNode: public MemBarNode {
 public:
   StoreFenceNode(Compile* C, int alias_idx, Node* precedent)
     : MemBarNode(C, alias_idx, precedent) {}
   virtual int Opcode() const;
 };
 // "Acquire" - no following ref can move before (but earlier refs can
 // follow, like an early Load stalled in cache).  Requires multi-cpu
 // visibility.  Inserted after a FastLock.
 class MemBarAcquireLockNode: public MemBarNode {
 public:
   MemBarAcquireLockNode(Compile* C, int alias_idx, Node* precedent)
     : MemBarNode(C, alias_idx, precedent) {}
   virtual int Opcode() const;
 };
 // "Release" - no earlier ref can move after (but later refs can move
 // up, like a speculative pipelined cache-hitting Load).  Requires
 // multi-cpu visibility.  Inserted before a FastUnLock.
 class MemBarReleaseLockNode: public MemBarNode {
 public:
   MemBarReleaseLockNode(Compile* C, int alias_idx, Node* precedent)
     : MemBarNode(C, alias_idx, precedent) {}
   virtual int Opcode() const;
 };
 class MemBarStoreStoreNode: public MemBarNode {
 public:
   MemBarStoreStoreNode(Compile* C, int alias_idx, Node* precedent)
     : MemBarNode(C, alias_idx, precedent) {
     init_class_id(Class_MemBarStoreStore);
   }
   virtual int Opcode() const;
 };
 // Ordering between a volatile store and a following volatile load.
 // Requires multi-CPU visibility?
 class MemBarVolatileNode: public MemBarNode {
 public:
   MemBarVolatileNode(Compile* C, int alias_idx, Node* precedent)
     : MemBarNode(C, alias_idx, precedent) {}
   virtual int Opcode() const;
 };
 // Ordering within the same CPU.  Used to order unsafe memory references
 // inside the compiler when we lack alias info.  Not needed "outside" the
 // compiler because the CPU does all the ordering for us.
 class MemBarCPUOrderNode: public MemBarNode {
 public:
   MemBarCPUOrderNode(Compile* C, int alias_idx, Node* precedent)
     : MemBarNode(C, alias_idx, precedent) {}
   virtual int Opcode() const;
   virtual uint ideal_reg() const { return 0; } // not matched in the AD file
 };
 // Isolation of object setup after an AllocateNode and before next safepoint.
 // (See comment in memnode.cpp near InitializeNode::InitializeNode for semantics.)
 class InitializeNode: public MemBarNode {
   friend class AllocateNode;
   enum {
     Incomplete    = 0,
     Complete      = 1,
     WithArraycopy = 2
   };
   int _is_complete;
   bool _does_not_escape;
 public:
   enum {
     Control    = TypeFunc::Control,
     Memory     = TypeFunc::Memory,     // MergeMem for states affected by this op
     RawAddress = TypeFunc::Parms+0,    // the newly-allocated raw address
     RawStores  = TypeFunc::Parms+1     // zero or more stores (or TOP)
   };
   InitializeNode(Compile* C, int adr_type, Node* rawoop);
   virtual int Opcode() const;
   virtual uint size_of() const { return sizeof(*this); }
   virtual uint ideal_reg() const { return 0; } // not matched in the AD file
   virtual const RegMask &in_RegMask(uint) const;  // mask for RawAddress
   // Manage incoming memory edges via a MergeMem on in(Memory):
   Node* memory(uint alias_idx);
   // The raw memory edge coming directly from the Allocation.
   // The contents of this memory are *always* all-zero-bits.
   Node* zero_memory() { return memory(Compile::AliasIdxRaw); }
   // Return the corresponding allocation for this initialization (or null if none).
   // (Note: Both InitializeNode::allocation and AllocateNode::initialization
   // are defined in graphKit.cpp, which sets up the bidirectional relation.)
   AllocateNode* allocation();
   // Anything other than zeroing in this init?
   bool is_non_zero();
   // An InitializeNode must completed before macro expansion is done.
   // Completion requires that the AllocateNode must be followed by
   // initialization of the new memory to zero, then to any initializers.
   bool is_complete() { return _is_complete != Incomplete; }
   bool is_complete_with_arraycopy() { return (_is_complete & WithArraycopy) != 0; }
   // Mark complete.  (Must not yet be complete.)
   void set_complete(PhaseGVN* phase);
   void set_complete_with_arraycopy() { _is_complete = Complete | WithArraycopy; }
   bool does_not_escape() { return _does_not_escape; }
   void set_does_not_escape() { _does_not_escape = true; }
 #ifdef ASSERT
   // ensure all non-degenerate stores are ordered and non-overlapping
   bool stores_are_sane(PhaseTransform* phase);
 #endif //ASSERT
   // See if this store can be captured; return offset where it initializes.
   // Return 0 if the store cannot be moved (any sort of problem).
   intptr_t can_capture_store(StoreNode* st, PhaseTransform* phase, bool can_reshape);
   // Capture another store; reformat it to write my internal raw memory.
   // Return the captured copy, else NULL if there is some sort of problem.
   Node* capture_store(StoreNode* st, intptr_t start, PhaseTransform* phase, bool can_reshape);
   // Find captured store which corresponds to the range [start..start+size).
   // Return my own memory projection (meaning the initial zero bits)
   // if there is no such store.  Return NULL if there is a problem.
   Node* find_captured_store(intptr_t start, int size_in_bytes, PhaseTransform* phase);
   // Called when the associated AllocateNode is expanded into CFG.
   Node* complete_stores(Node* rawctl, Node* rawmem, Node* rawptr,
                         intptr_t header_size, Node* size_in_bytes,
                         PhaseGVN* phase);
  private:
   void remove_extra_zeroes();
   // Find out where a captured store should be placed (or already is placed).
   int captured_store_insertion_point(intptr_t start, int size_in_bytes,
                                      PhaseTransform* phase);
   static intptr_t get_store_offset(Node* st, PhaseTransform* phase);
   Node* make_raw_address(intptr_t offset, PhaseTransform* phase);
   bool detect_init_independence(Node* n, int& count);
   void coalesce_subword_stores(intptr_t header_size, Node* size_in_bytes,
                                PhaseGVN* phase);
   intptr_t find_next_fullword_store(uint i, PhaseGVN* phase);
 };
 //------------------------------MergeMem---------------------------------------
 // (See comment in memnode.cpp near MergeMemNode::MergeMemNode for semantics.)
 class MergeMemNode: public Node {
   virtual uint hash() const ;                  // { return NO_HASH; }
   virtual uint cmp( const Node &n ) const ;    // Always fail, except on self
   friend class MergeMemStream;
   MergeMemNode(Node* def);  // clients use MergeMemNode::make
 public:
   // If the input is a whole memory state, clone it with all its slices intact.
   // Otherwise, make a new memory state with just that base memory input.
   // In either case, the result is a newly created MergeMem.
   static MergeMemNode* make(Compile* C, Node* base_memory);
   virtual int Opcode() const;
   virtual Node *Identity( PhaseTransform *phase );
   virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
   virtual uint ideal_reg() const { return NotAMachineReg; }
   virtual uint match_edge(uint idx) const { return 0; }
   virtual const RegMask &out_RegMask() const;
   virtual const Type *bottom_type() const { return Type::MEMORY; }
   virtual const TypePtr *adr_type() const { return TypePtr::BOTTOM; }
   // sparse accessors
   // Fetch the previously stored "set_memory_at", or else the base memory.
   // (Caller should clone it if it is a phi-nest.)
   Node* memory_at(uint alias_idx) const;
   // set the memory, regardless of its previous value
   void set_memory_at(uint alias_idx, Node* n);
   // the "base" is the memory that provides the non-finite support
   Node* base_memory() const       { return in(Compile::AliasIdxBot); }
   // warning: setting the base can implicitly set any of the other slices too
   void set_base_memory(Node* def);
   // sentinel value which denotes a copy of the base memory:
   Node*   empty_memory() const    { return in(Compile::AliasIdxTop); }
   static Node* make_empty_memory(); // where the sentinel comes from
   bool is_empty_memory(Node* n) const { assert((n == empty_memory()) == n->is_top(), "sanity"); return n->is_top(); }
   // hook for the iterator, to perform any necessary setup
   void iteration_setup(const MergeMemNode* other = NULL);
   // push sentinels until I am at least as long as the other (semantic no-op)
   void grow_to_match(const MergeMemNode* other);
   bool verify_sparse() const PRODUCT_RETURN0;
 #ifndef PRODUCT
   virtual void dump_spec(outputStream *st) const;
 #endif
 };
 class MergeMemStream : public StackObj {
  private:
   MergeMemNode*       _mm;
   const MergeMemNode* _mm2;  // optional second guy, contributes non-empty iterations
   Node*               _mm_base;  // loop-invariant base memory of _mm
   int                 _idx;
   int                 _cnt;
   Node*               _mem;
   Node*               _mem2;
   int                 _cnt2;
   void init(MergeMemNode* mm, const MergeMemNode* mm2 = NULL) {
     // subsume_node will break sparseness at times, whenever a memory slice
     // folds down to a copy of the base ("fat") memory.  In such a case,
     // the raw edge will update to base, although it should be top.
     // This iterator will recognize either top or base_memory as an
     // "empty" slice.  See is_empty, is_empty2, and next below.
     //
     // The sparseness property is repaired in MergeMemNode::Ideal.
     // As long as access to a MergeMem goes through this iterator
     // or the memory_at accessor, flaws in the sparseness will
     // never be observed.
     //
     // Also, iteration_setup repairs sparseness.
     assert(mm->verify_sparse(), "please, no dups of base");
     assert(mm2==NULL || mm2->verify_sparse(), "please, no dups of base");
     _mm  = mm;
     _mm_base = mm->base_memory();
     _mm2 = mm2;
     _cnt = mm->req();
     _idx = Compile::AliasIdxBot-1; // start at the base memory
     _mem = NULL;
     _mem2 = NULL;
   }
 #ifdef ASSERT
   Node* check_memory() const {
     if (at_base_memory())
       return _mm->base_memory();
     else if ((uint)_idx < _mm->req() && !_mm->in(_idx)->is_top())
       return _mm->memory_at(_idx);
     else
       return _mm_base;
   }
   Node* check_memory2() const {
     return at_base_memory()? _mm2->base_memory(): _mm2->memory_at(_idx);
   }
 #endif
   static bool match_memory(Node* mem, const MergeMemNode* mm, int idx) PRODUCT_RETURN0;
   void assert_synch() const {
     assert(!_mem || _idx >= _cnt || match_memory(_mem, _mm, _idx),
            "no side-effects except through the stream");
   }
  public:
   // expected usages:
   // for (MergeMemStream mms(mem->is_MergeMem()); next_non_empty(); ) { ... }
   // for (MergeMemStream mms(mem1, mem2); next_non_empty2(); ) { ... }
   // iterate over one merge
   MergeMemStream(MergeMemNode* mm) {
     mm->iteration_setup();
     init(mm);
     debug_only(_cnt2 = 999);
   }
   // iterate in parallel over two merges
   // only iterates through non-empty elements of mm2
   MergeMemStream(MergeMemNode* mm, const MergeMemNode* mm2) {
     assert(mm2, "second argument must be a MergeMem also");
     ((MergeMemNode*)mm2)->iteration_setup();  // update hidden state
     mm->iteration_setup(mm2);
     init(mm, mm2);
     _cnt2 = mm2->req();
   }
 #ifdef ASSERT
   ~MergeMemStream() {
     assert_synch();
   }
 #endif
   MergeMemNode* all_memory() const {
     return _mm;
   }
   Node* base_memory() const {
     assert(_mm_base == _mm->base_memory(), "no update to base memory, please");
     return _mm_base;
   }
   const MergeMemNode* all_memory2() const {
     assert(_mm2 != NULL, "");
     return _mm2;
   }
   bool at_base_memory() const {
     return _idx == Compile::AliasIdxBot;
   }
   int alias_idx() const {
     assert(_mem, "must call next 1st");
     return _idx;
   }
   const TypePtr* adr_type() const {
     return Compile::current()->get_adr_type(alias_idx());
   }
   const TypePtr* adr_type(Compile* C) const {
     return C->get_adr_type(alias_idx());
   }
   bool is_empty() const {
     assert(_mem, "must call next 1st");
     assert(_mem->is_top() == (_mem==_mm->empty_memory()), "correct sentinel");
     return _mem->is_top();
   }
   bool is_empty2() const {
     assert(_mem2, "must call next 1st");
     assert(_mem2->is_top() == (_mem2==_mm2->empty_memory()), "correct sentinel");
     return _mem2->is_top();
   }
   Node* memory() const {
     assert(!is_empty(), "must not be empty");
     assert_synch();
     return _mem;
   }
   // get the current memory, regardless of empty or non-empty status
   Node* force_memory() const {
     assert(!is_empty() || !at_base_memory(), "");
     // Use _mm_base to defend against updates to _mem->base_memory().
     Node *mem = _mem->is_top() ? _mm_base : _mem;
     assert(mem == check_memory(), "");
     return mem;
   }
   Node* memory2() const {
     assert(_mem2 == check_memory2(), "");
     return _mem2;
   }
   void set_memory(Node* mem) {
     if (at_base_memory()) {
       // Note that this does not change the invariant _mm_base.
       _mm->set_base_memory(mem);
     } else {
       _mm->set_memory_at(_idx, mem);
     }
     _mem = mem;
     assert_synch();
   }
   // Recover from a side effect to the MergeMemNode.
   void set_memory() {
     _mem = _mm->in(_idx);
   }
   bool next()  { return next(false); }
   bool next2() { return next(true); }
   bool next_non_empty()  { return next_non_empty(false); }
   bool next_non_empty2() { return next_non_empty(true); }
   // next_non_empty2 can yield states where is_empty() is true
  private:
   // find the next item, which might be empty
   bool next(bool have_mm2) {
     assert((_mm2 != NULL) == have_mm2, "use other next");
     assert_synch();
     if (++_idx < _cnt) {
       // Note:  This iterator allows _mm to be non-sparse.
       // It behaves the same whether _mem is top or base_memory.
       _mem = _mm->in(_idx);
       if (have_mm2)
         _mem2 = _mm2->in((_idx < _cnt2) ? _idx : Compile::AliasIdxTop);
       return true;
     }
     return false;
   }
   // find the next non-empty item
   bool next_non_empty(bool have_mm2) {
     while (next(have_mm2)) {
       if (!is_empty()) {
         // make sure _mem2 is filled in sensibly
         if (have_mm2 && _mem2->is_top())  _mem2 = _mm2->base_memory();
         return true;
       } else if (have_mm2 && !is_empty2()) {
         return true;   // is_empty() == true
       }
     }
     return false;
   }
 };
 //------------------------------Prefetch---------------------------------------
 // Non-faulting prefetch load.  Prefetch for many reads.
 class PrefetchReadNode : public Node {
 public:
   PrefetchReadNode(Node *abio, Node *adr) : Node(0,abio,adr) {}
   virtual int Opcode() const;
   virtual uint ideal_reg() const { return NotAMachineReg; }
   virtual uint match_edge(uint idx) const { return idx==2; }
   virtual const Type *bottom_type() const { return Type::ABIO; }
 };
 // Non-faulting prefetch load.  Prefetch for many reads & many writes.
 class PrefetchWriteNode : public Node {
 public:
   PrefetchWriteNode(Node *abio, Node *adr) : Node(0,abio,adr) {}
   virtual int Opcode() const;
   virtual uint ideal_reg() const { return NotAMachineReg; }
   virtual uint match_edge(uint idx) const { return idx==2; }
   virtual const Type *bottom_type() const { return Type::ABIO; }
 };
 // Allocation prefetch which may fault, TLAB size have to be adjusted.
 class PrefetchAllocationNode : public Node {
 public:
   PrefetchAllocationNode(Node *mem, Node *adr) : Node(0,mem,adr) {}
   virtual int Opcode() const;
   virtual uint ideal_reg() const { return NotAMachineReg; }
   virtual uint match_edge(uint idx) const { return idx==2; }
   virtual const Type *bottom_type() const { return ( AllocatePrefetchStyle == 3 ) ? Type::MEMORY : Type::ABIO; }
 };
 #endif // SHARE_VM_OPTO_MEMNODE_HPP

Mercurial > jdk8-mips64-public > hotspot / annotate

src/share/vm/opto/memnode.hpp@c1c199dde5c9 (annotated)

src/share/vm/opto/memnode.hpp