X-Git-Url: http://plrg.eecs.uci.edu/git/?a=blobdiff_plain;ds=sidebyside;f=include%2Fllvm%2FInstrTypes.h;h=ef0ee89a3edac9631d30057936d984c6bd68803e;hb=051a950000e21935165db56695e35bade668193b;hp=6d35ed5d50f5d19b96442f006d0a891972ed1c71;hpb=3bcd6394ecd3c928d2ea05bb64cacdcae8dc677a;p=oota-llvm.git

diff --git a/include/llvm/InstrTypes.h b/include/llvm/InstrTypes.h
index 6d35ed5d50f..ef0ee89a3ed 100644
--- a/include/llvm/InstrTypes.h
+++ b/include/llvm/InstrTypes.h
@@ -1,7 +1,14 @@
-//===-- llvm/InstrTypes.h - Important Instruction subclasses -----*- C++ -*--=//
+//===-- llvm/InstrTypes.h - Important Instruction subclasses ----*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
 //
 // This file defines various meta classes of instructions that exist in the VM
-// representation.  Specific concrete subclasses of these may be found in the 
+// representation.  Specific concrete subclasses of these may be found in the
 // i*.h files...
 //
 //===----------------------------------------------------------------------===//
@@ -10,144 +17,589 @@
 #define LLVM_INSTRUCTION_TYPES_H
 
 #include "llvm/Instruction.h"
-#include <list>
-#include <vector>
 
-class Method;
-class SymTabValue;
+namespace llvm {
 
 //===----------------------------------------------------------------------===//
 //                            TerminatorInst Class
 //===----------------------------------------------------------------------===//
 
-// TerminatorInst - Subclasses of this class are all able to terminate a basic 
-// block.  Thus, these are all the flow control type of operations.
-//
+/// TerminatorInst - Subclasses of this class are all able to terminate a basic
+/// block.  Thus, these are all the flow control type of operations.
+///
 class TerminatorInst : public Instruction {
+protected:
+  TerminatorInst(const Type *Ty, Instruction::TermOps iType,
+                 Use *Ops, unsigned NumOps,
+                 Instruction *InsertBefore = 0)
+    : Instruction(Ty, iType, Ops, NumOps, InsertBefore) {}
+
+  TerminatorInst(const Type *Ty, Instruction::TermOps iType,
+                 Use *Ops, unsigned NumOps, BasicBlock *InsertAtEnd)
+    : Instruction(Ty, iType, Ops, NumOps, InsertAtEnd) {}
+
+  // Out of line virtual method, so the vtable, etc has a home.
+  ~TerminatorInst();
+
+  /// Virtual methods - Terminators should overload these and provide inline
+  /// overrides of non-V methods.
+  virtual BasicBlock *getSuccessorV(unsigned idx) const = 0;
+  virtual unsigned getNumSuccessorsV() const = 0;
+  virtual void setSuccessorV(unsigned idx, BasicBlock *B) = 0;
 public:
-  TerminatorInst(unsigned iType);
-  inline ~TerminatorInst() {}
 
-  // Terminators must implement the methods required by Instruction...
   virtual Instruction *clone() const = 0;
-  virtual void dropAllReferences() = 0;
-  virtual string getOpcode() const = 0;
 
-  virtual bool setOperand(unsigned i, Value *Val) = 0;
-  virtual const Value *getOperand(unsigned i) const = 0;
-  inline Value *getOperand(unsigned i) {
-    return (Value*)((const Instruction *)this)->getOperand(i);
+  /// getNumSuccessors - Return the number of successors that this terminator
+  /// has.
+  unsigned getNumSuccessors() const {
+    return getNumSuccessorsV();
   }
 
-  // Additionally, they must provide a method to get at the successors of this
-  // terminator instruction.  If 'idx' is out of range, a null pointer shall be
-  // returned.
-  //
-  virtual const BasicBlock *getSuccessor(unsigned idx) const = 0;
-  virtual unsigned getNumSuccessors() const = 0;
+  /// getSuccessor - Return the specified successor.
+  ///
+  BasicBlock *getSuccessor(unsigned idx) const {
+    return getSuccessorV(idx);
+  }
 
-  inline BasicBlock *getSuccessor(unsigned idx) {
-    return (BasicBlock*)((const TerminatorInst *)this)->getSuccessor(idx);
+  /// setSuccessor - Update the specified successor to point at the provided
+  /// block.
+  void setSuccessor(unsigned idx, BasicBlock *B) {
+    setSuccessorV(idx, B);
   }
-};
 
+  // Methods for support type inquiry through isa, cast, and dyn_cast:
+  static inline bool classof(const TerminatorInst *) { return true; }
+  static inline bool classof(const Instruction *I) {
+    return I->getOpcode() >= TermOpsBegin && I->getOpcode() < TermOpsEnd;
+  }
+  static inline bool classof(const Value *V) {
+    return isa<Instruction>(V) && classof(cast<Instruction>(V));
+  }
+};
 
 //===----------------------------------------------------------------------===//
-//                            UnaryOperator Class
+//                          UnaryInstruction Class
 //===----------------------------------------------------------------------===//
 
-class UnaryOperator : public Instruction {
-  Use Source;
+class UnaryInstruction : public Instruction {
+  void *operator new(size_t, unsigned); // Do not implement
+  Use Op;
+  
+  // avoiding warning: 'this' : used in base member initializer list
+  UnaryInstruction* this_() { return this; }
+protected:
+  UnaryInstruction(const Type *Ty, unsigned iType, Value *V, Instruction *IB =0)
+    : Instruction(Ty, iType, &Op, 1, IB), Op(V, this_()) {
+  }
+  UnaryInstruction(const Type *Ty, unsigned iType, Value *V, BasicBlock *IAE)
+    : Instruction(Ty, iType, &Op, 1, IAE), Op(V, this_()) {
+  }
 public:
+  // allocate space for exactly one operand
+  void *operator new(size_t s) {
+    return User::operator new(s, 1);
+  }
 
-  // create() - Construct a unary instruction, given the opcode
-  // and its operand.
-  //
-  static UnaryOperator *create(unsigned Op, Value *Source);
+  // Out of line virtual method, so the vtable, etc has a home.
+  ~UnaryInstruction();
 
-  UnaryOperator(Value *S, unsigned iType, const string &Name = "")
-      : Instruction(S->getType(), iType, Name), Source(S, this) {
+  // Transparently provide more efficient getOperand methods.
+  Value *getOperand(unsigned i) const {
+    assert(i == 0 && "getOperand() out of range!");
+    return Op;
+  }
+  void setOperand(unsigned i, Value *Val) {
+    assert(i == 0 && "setOperand() out of range!");
+    Op = Val;
   }
-  inline ~UnaryOperator() { dropAllReferences(); }
+  unsigned getNumOperands() const { return 1; }
+  
+  // Methods for support type inquiry through isa, cast, and dyn_cast:
+  static inline bool classof(const UnaryInstruction *) { return true; }
+  static inline bool classof(const Instruction *I) {
+    return I->getOpcode() == Instruction::Malloc ||
+           I->getOpcode() == Instruction::Alloca ||
+           I->getOpcode() == Instruction::Free ||
+           I->getOpcode() == Instruction::Load ||
+           I->getOpcode() == Instruction::VAArg ||
+           (I->getOpcode() >= CastOpsBegin && I->getOpcode() < CastOpsEnd);
+  }
+  static inline bool classof(const Value *V) {
+    return isa<Instruction>(V) && classof(cast<Instruction>(V));
+  }
+};
 
-  virtual Instruction *clone() const { 
-    return create(getInstType(), Source);
+//===----------------------------------------------------------------------===//
+//                           BinaryOperator Class
+//===----------------------------------------------------------------------===//
+
+class BinaryOperator : public Instruction {
+  void *operator new(size_t, unsigned); // Do not implement
+  Use Ops[2];
+protected:
+  void init(BinaryOps iType);
+  BinaryOperator(BinaryOps iType, Value *S1, Value *S2, const Type *Ty,
+                 const std::string &Name, Instruction *InsertBefore);
+  BinaryOperator(BinaryOps iType, Value *S1, Value *S2, const Type *Ty,
+                 const std::string &Name, BasicBlock *InsertAtEnd);
+public:
+  // allocate space for exactly two operands
+  void *operator new(size_t s) {
+    return User::operator new(s, 2);
   }
 
-  virtual void dropAllReferences() {
-    Source = 0;
+  /// Transparently provide more efficient getOperand methods.
+  Value *getOperand(unsigned i) const {
+    assert(i < 2 && "getOperand() out of range!");
+    return Ops[i];
+  }
+  void setOperand(unsigned i, Value *Val) {
+    assert(i < 2 && "setOperand() out of range!");
+    Ops[i] = Val;
   }
+  unsigned getNumOperands() const { return 2; }
+
+  /// create() - Construct a binary instruction, given the opcode and the two
+  /// operands.  Optionally (if InstBefore is specified) insert the instruction
+  /// into a BasicBlock right before the specified instruction.  The specified
+  /// Instruction is allowed to be a dereferenced end iterator.
+  ///
+  static BinaryOperator *create(BinaryOps Op, Value *S1, Value *S2,
+                                const std::string &Name = "",
+                                Instruction *InsertBefore = 0);
 
-  virtual string getOpcode() const = 0;
+  /// create() - Construct a binary instruction, given the opcode and the two
+  /// operands.  Also automatically insert this instruction to the end of the
+  /// BasicBlock specified.
+  ///
+  static BinaryOperator *create(BinaryOps Op, Value *S1, Value *S2,
+                                const std::string &Name,
+                                BasicBlock *InsertAtEnd);
 
-  virtual unsigned getNumOperands() const { return 1; }
-  inline Value *getOperand(unsigned i) {
-    return (i == 0) ? Source : 0;
+  /// create* - These methods just forward to create, and are useful when you
+  /// statically know what type of instruction you're going to create.  These
+  /// helpers just save some typing.
+#define HANDLE_BINARY_INST(N, OPC, CLASS) \
+  static BinaryOperator *create##OPC(Value *V1, Value *V2, \
+                                     const std::string &Name = "") {\
+    return create(Instruction::OPC, V1, V2, Name);\
   }
-  virtual const Value *getOperand(unsigned i) const {
-    return (i == 0) ? Source : 0;
+#include "llvm/Instruction.def"
+#define HANDLE_BINARY_INST(N, OPC, CLASS) \
+  static BinaryOperator *create##OPC(Value *V1, Value *V2, \
+                                     const std::string &Name, BasicBlock *BB) {\
+    return create(Instruction::OPC, V1, V2, Name, BB);\
   }
-  virtual bool setOperand(unsigned i, Value *Val) {
-    // assert(Val && "operand must not be null!");
-    if (i) return false;
-    Source = Val;
-    return true;
+#include "llvm/Instruction.def"
+#define HANDLE_BINARY_INST(N, OPC, CLASS) \
+  static BinaryOperator *create##OPC(Value *V1, Value *V2, \
+                                     const std::string &Name, Instruction *I) {\
+    return create(Instruction::OPC, V1, V2, Name, I);\
   }
-};
+#include "llvm/Instruction.def"
+
+
+  /// Helper functions to construct and inspect unary operations (NEG and NOT)
+  /// via binary operators SUB and XOR:
+  ///
+  /// createNeg, createNot - Create the NEG and NOT
+  ///     instructions out of SUB and XOR instructions.
+  ///
+  static BinaryOperator *createNeg(Value *Op, const std::string &Name = "",
+                                   Instruction *InsertBefore = 0);
+  static BinaryOperator *createNeg(Value *Op, const std::string &Name,
+                                   BasicBlock *InsertAtEnd);
+  static BinaryOperator *createNot(Value *Op, const std::string &Name = "",
+                                   Instruction *InsertBefore = 0);
+  static BinaryOperator *createNot(Value *Op, const std::string &Name,
+                                   BasicBlock *InsertAtEnd);
 
+  /// isNeg, isNot - Check if the given Value is a NEG or NOT instruction.
+  ///
+  static bool isNeg(const Value *V);
+  static bool isNot(const Value *V);
 
+  /// getNegArgument, getNotArgument - Helper functions to extract the
+  ///     unary argument of a NEG or NOT operation implemented via Sub or Xor.
+  ///
+  static const Value *getNegArgument(const Value *BinOp);
+  static       Value *getNegArgument(      Value *BinOp);
+  static const Value *getNotArgument(const Value *BinOp);
+  static       Value *getNotArgument(      Value *BinOp);
+
+  BinaryOps getOpcode() const {
+    return static_cast<BinaryOps>(Instruction::getOpcode());
+  }
+
+  virtual BinaryOperator *clone() const;
+
+  /// swapOperands - Exchange the two operands to this instruction.
+  /// This instruction is safe to use on any binary instruction and
+  /// does not modify the semantics of the instruction.  If the
+  /// instruction is order dependent (SetLT f.e.) the opcode is
+  /// changed.  If the instruction cannot be reversed (ie, it's a Div),
+  /// then return true.
+  ///
+  bool swapOperands();
+
+  // Methods for support type inquiry through isa, cast, and dyn_cast:
+  static inline bool classof(const BinaryOperator *) { return true; }
+  static inline bool classof(const Instruction *I) {
+    return I->getOpcode() >= BinaryOpsBegin && I->getOpcode() < BinaryOpsEnd;
+  }
+  static inline bool classof(const Value *V) {
+    return isa<Instruction>(V) && classof(cast<Instruction>(V));
+  }
+};
 
 //===----------------------------------------------------------------------===//
-//                           BinaryOperator Class
+//                               CastInst Class
 //===----------------------------------------------------------------------===//
 
-class BinaryOperator : public Instruction {
-  Use Source1, Source2;
+/// CastInst - This is the base class for all instructions that perform data
+/// casts. It is simply provided so that instruction category testing
+/// can be performed with code like:
+///
+/// if (isa<CastInst>(Instr)) { ... }
+/// @brief Base class of casting instructions.
+class CastInst : public UnaryInstruction {
+  /// @brief Copy constructor
+  CastInst(const CastInst &CI)
+    : UnaryInstruction(CI.getType(), CI.getOpcode(), CI.getOperand(0)) {
+  }
+  /// @brief Do not allow default construction
+  CastInst(); 
+protected:
+  /// @brief Constructor with insert-before-instruction semantics for subclasses
+  CastInst(const Type *Ty, unsigned iType, Value *S, 
+           const std::string &Name = "", Instruction *InsertBefore = 0)
+    : UnaryInstruction(Ty, iType, S, InsertBefore) {
+    setName(Name);
+  }
+  /// @brief Constructor with insert-at-end-of-block semantics for subclasses
+  CastInst(const Type *Ty, unsigned iType, Value *S, 
+           const std::string &Name, BasicBlock *InsertAtEnd)
+    : UnaryInstruction(Ty, iType, S, InsertAtEnd) {
+    setName(Name);
+  }
 public:
+  /// Provides a way to construct any of the CastInst subclasses using an 
+  /// opcode instead of the subclass's constructor. The opcode must be in the
+  /// CastOps category (Instruction::isCast(opcode) returns true). This
+  /// constructor has insert-before-instruction semantics to automatically
+  /// insert the new CastInst before InsertBefore (if it is non-null).
+  /// @brief Construct any of the CastInst subclasses
+  static CastInst *create(
+    Instruction::CastOps,    ///< The opcode of the cast instruction
+    Value *S,                ///< The value to be casted (operand 0)
+    const Type *Ty,          ///< The type to which cast should be made
+    const std::string &Name = "", ///< Name for the instruction
+    Instruction *InsertBefore = 0 ///< Place to insert the instruction
+  );
+  /// Provides a way to construct any of the CastInst subclasses using an
+  /// opcode instead of the subclass's constructor. The opcode must be in the
+  /// CastOps category. This constructor has insert-at-end-of-block semantics
+  /// to automatically insert the new CastInst at the end of InsertAtEnd (if
+  /// its non-null).
+  /// @brief Construct any of the CastInst subclasses
+  static CastInst *create(
+    Instruction::CastOps,    ///< The opcode for the cast instruction
+    Value *S,                ///< The value to be casted (operand 0)
+    const Type *Ty,          ///< The type to which operand is casted
+    const std::string &Name, ///< The name for the instruction
+    BasicBlock *InsertAtEnd  ///< The block to insert the instruction into
+  );
+
+  /// @brief Create a ZExt or BitCast cast instruction
+  static CastInst *createZExtOrBitCast(
+    Value *S,                ///< The value to be casted (operand 0)
+    const Type *Ty,          ///< The type to which cast should be made
+    const std::string &Name = "", ///< Name for the instruction
+    Instruction *InsertBefore = 0 ///< Place to insert the instruction
+  );
+
+  /// @brief Create a ZExt or BitCast cast instruction
+  static CastInst *createZExtOrBitCast(
+    Value *S,                ///< The value to be casted (operand 0)
+    const Type *Ty,          ///< The type to which operand is casted
+    const std::string &Name, ///< The name for the instruction
+    BasicBlock *InsertAtEnd  ///< The block to insert the instruction into
+  );
+
+  /// @brief Create a SExt or BitCast cast instruction
+  static CastInst *createSExtOrBitCast(
+    Value *S,                ///< The value to be casted (operand 0)
+    const Type *Ty,          ///< The type to which cast should be made
+    const std::string &Name = "", ///< Name for the instruction
+    Instruction *InsertBefore = 0 ///< Place to insert the instruction
+  );
+
+  /// @brief Create a BitCast or a PtrToInt cast instruction
+  static CastInst *createPointerCast(
+    Value *S,                ///< The pointer value to be casted (operand 0)
+    const Type *Ty,          ///< The type to which operand is casted
+    const std::string &Name, ///< The name for the instruction
+    BasicBlock *InsertAtEnd  ///< The block to insert the instruction into
+  );
+
+  /// @brief Create a BitCast or a PtrToInt cast instruction
+  static CastInst *createPointerCast(
+    Value *S,                ///< The pointer value to be casted (operand 0)
+    const Type *Ty,          ///< The type to which cast should be made
+    const std::string &Name = "", ///< Name for the instruction
+    Instruction *InsertBefore = 0 ///< Place to insert the instruction
+  );
+
+  /// @brief Create a ZExt, BitCast, or Trunc for int -> int casts.
+  static CastInst *createIntegerCast(
+    Value *S,                ///< The pointer value to be casted (operand 0)
+    const Type *Ty,          ///< The type to which cast should be made
+    bool isSigned,           ///< Whether to regard S as signed or not
+    const std::string &Name = "", ///< Name for the instruction
+    Instruction *InsertBefore = 0 ///< Place to insert the instruction
+  );
+
+  /// @brief Create a ZExt, BitCast, or Trunc for int -> int casts.
+  static CastInst *createIntegerCast(
+    Value *S,                ///< The integer value to be casted (operand 0)
+    const Type *Ty,          ///< The integer type to which operand is casted
+    bool isSigned,           ///< Whether to regard S as signed or not
+    const std::string &Name, ///< The name for the instruction
+    BasicBlock *InsertAtEnd  ///< The block to insert the instruction into
+  );
+
+  /// @brief Create an FPExt, BitCast, or FPTrunc for fp -> fp casts
+  static CastInst *createFPCast(
+    Value *S,                ///< The floating point value to be casted 
+    const Type *Ty,          ///< The floating point type to cast to
+    const std::string &Name = "", ///< Name for the instruction
+    Instruction *InsertBefore = 0 ///< Place to insert the instruction
+  );
+
+  /// @brief Create an FPExt, BitCast, or FPTrunc for fp -> fp casts
+  static CastInst *createFPCast(
+    Value *S,                ///< The floating point value to be casted 
+    const Type *Ty,          ///< The floating point type to cast to
+    const std::string &Name, ///< The name for the instruction
+    BasicBlock *InsertAtEnd  ///< The block to insert the instruction into
+  );
+
+  /// @brief Create a SExt or BitCast cast instruction
+  static CastInst *createSExtOrBitCast(
+    Value *S,                ///< The value to be casted (operand 0)
+    const Type *Ty,          ///< The type to which operand is casted
+    const std::string &Name, ///< The name for the instruction
+    BasicBlock *InsertAtEnd  ///< The block to insert the instruction into
+  );
+
+  /// @brief Create a Trunc or BitCast cast instruction
+  static CastInst *createTruncOrBitCast(
+    Value *S,                ///< The value to be casted (operand 0)
+    const Type *Ty,          ///< The type to which cast should be made
+    const std::string &Name = "", ///< Name for the instruction
+    Instruction *InsertBefore = 0 ///< Place to insert the instruction
+  );
+
+  /// @brief Create a Trunc or BitCast cast instruction
+  static CastInst *createTruncOrBitCast(
+    Value *S,                ///< The value to be casted (operand 0)
+    const Type *Ty,          ///< The type to which operand is casted
+    const std::string &Name, ///< The name for the instruction
+    BasicBlock *InsertAtEnd  ///< The block to insert the instruction into
+  );
+
+  /// @brief Check whether it is valid to call getCastOpcode for these types.
+  static bool isCastable(
+    const Type *SrcTy, ///< The Type from which the value should be cast.
+    const Type *DestTy ///< The Type to which the value should be cast.
+  );
+
+  /// Returns the opcode necessary to cast Val into Ty using usual casting
+  /// rules.
+  /// @brief Infer the opcode for cast operand and type
+  static Instruction::CastOps getCastOpcode(
+    const Value *Val, ///< The value to cast
+    bool SrcIsSigned, ///< Whether to treat the source as signed
+    const Type *Ty,   ///< The Type to which the value should be casted
+    bool DstIsSigned  ///< Whether to treate the dest. as signed
+  );
+
+  /// There are several places where we need to know if a cast instruction 
+  /// only deals with integer source and destination types. To simplify that
+  /// logic, this method is provided.
+  /// @returns true iff the cast has only integral typed operand and dest type.
+  /// @brief Determine if this is an integer-only cast.
+  bool isIntegerCast() const;
+
+  /// A lossless cast is one that does not alter the basic value. It implies
+  /// a no-op cast but is more stringent, preventing things like int->float,
+  /// long->double, int->ptr, or vector->anything. 
+  /// @returns true iff the cast is lossless.
+  /// @brief Determine if this is a lossless cast.
+  bool isLosslessCast() const;
+
+  /// A no-op cast is one that can be effected without changing any bits. 
+  /// It implies that the source and destination types are the same size. The
+  /// IntPtrTy argument is used to make accurate determinations for casts 
+  /// involving Integer and Pointer types. They are no-op casts if the integer
+  /// is the same size as the pointer. However, pointer size varies with 
+  /// platform. Generally, the result of TargetData::getIntPtrType() should be
+  /// passed in. If that's not available, use Type::Int64Ty, which will make
+  /// the isNoopCast call conservative.
+  /// @brief Determine if this cast is a no-op cast. 
+  bool isNoopCast(
+    const Type *IntPtrTy ///< Integer type corresponding to pointer
+  ) const;
+
+  /// Determine how a pair of casts can be eliminated, if they can be at all.
+  /// This is a helper function for both CastInst and ConstantExpr.
+  /// @returns 0 if the CastInst pair can't be eliminated
+  /// @returns Instruction::CastOps value for a cast that can replace 
+  /// the pair, casting SrcTy to DstTy.
+  /// @brief Determine if a cast pair is eliminable
+  static unsigned isEliminableCastPair(
+    Instruction::CastOps firstOpcode,  ///< Opcode of first cast
+    Instruction::CastOps secondOpcode, ///< Opcode of second cast
+    const Type *SrcTy, ///< SrcTy of 1st cast
+    const Type *MidTy, ///< DstTy of 1st cast & SrcTy of 2nd cast
+    const Type *DstTy, ///< DstTy of 2nd cast
+    const Type *IntPtrTy ///< Integer type corresponding to Ptr types
+  );
+
+  /// @brief Return the opcode of this CastInst
+  Instruction::CastOps getOpcode() const { 
+    return Instruction::CastOps(Instruction::getOpcode()); 
+  }
 
-  // create() - Construct a binary instruction, given the opcode
-  // and the two operands.
-  //
-  static BinaryOperator *create(unsigned Op, Value *S1, Value *S2,
-				const string &Name = "");
+  /// @brief Return the source type, as a convenience
+  const Type* getSrcTy() const { return getOperand(0)->getType(); }
+  /// @brief Return the destination type, as a convenience
+  const Type* getDestTy() const { return getType(); }
 
-  BinaryOperator(unsigned iType, Value *S1, Value *S2, 
-                 const string &Name = "") 
-    : Instruction(S1->getType(), iType, Name), Source1(S1, this), 
-      Source2(S2, this){
-    assert(S1 && S2 && S1->getType() == S2->getType());
+  /// This method can be used to determine if a cast from S to DstTy using
+  /// Opcode op is valid or not. 
+  /// @returns true iff the proposed cast is valid.
+  /// @brief Determine if a cast is valid without creating one.
+  static bool castIsValid(Instruction::CastOps op, Value *S, const Type *DstTy);
+
+  /// @brief Methods for support type inquiry through isa, cast, and dyn_cast:
+  static inline bool classof(const CastInst *) { return true; }
+  static inline bool classof(const Instruction *I) {
+    return I->getOpcode() >= CastOpsBegin && I->getOpcode() < CastOpsEnd;
+  }
+  static inline bool classof(const Value *V) {
+    return isa<Instruction>(V) && classof(cast<Instruction>(V));
   }
-  inline ~BinaryOperator() { dropAllReferences(); }
+};
+
+//===----------------------------------------------------------------------===//
+//                               CmpInst Class
+//===----------------------------------------------------------------------===//
 
-  virtual Instruction *clone() const {
-    return create(getInstType(), Source1, Source2);
+/// This class is the base class for the comparison instructions. 
+/// @brief Abstract base class of comparison instructions.
+class CmpInst: public Instruction {
+  void *operator new(size_t, unsigned);  // DO NOT IMPLEMENT
+  CmpInst(); // do not implement
+protected:
+  CmpInst(Instruction::OtherOps op, unsigned short pred, Value *LHS, Value *RHS,
+          const std::string &Name = "", Instruction *InsertBefore = 0);
+  
+  CmpInst(Instruction::OtherOps op, unsigned short pred, Value *LHS, Value *RHS,
+          const std::string &Name, BasicBlock *InsertAtEnd);
+
+  Use Ops[2]; // CmpInst instructions always have 2 operands, optimize
+
+public:
+  // allocate space for exactly two operands
+  void *operator new(size_t s) {
+    return User::operator new(s, 2);
   }
+  /// Construct a compare instruction, given the opcode, the predicate and 
+  /// the two operands.  Optionally (if InstBefore is specified) insert the 
+  /// instruction into a BasicBlock right before the specified instruction.  
+  /// The specified Instruction is allowed to be a dereferenced end iterator.
+  /// @brief Create a CmpInst
+  static CmpInst *create(OtherOps Op, unsigned short predicate, Value *S1, 
+                         Value *S2, const std::string &Name = "",
+                         Instruction *InsertBefore = 0);
 
-  virtual void dropAllReferences() {
-    Source1 = Source2 = 0;
+  /// Construct a compare instruction, given the opcode, the predicate and the 
+  /// two operands.  Also automatically insert this instruction to the end of 
+  /// the BasicBlock specified.
+  /// @brief Create a CmpInst
+  static CmpInst *create(OtherOps Op, unsigned short predicate, Value *S1, 
+                         Value *S2, const std::string &Name, 
+                         BasicBlock *InsertAtEnd);
+
+  /// @brief Get the opcode casted to the right type
+  OtherOps getOpcode() const {
+    return static_cast<OtherOps>(Instruction::getOpcode());
   }
 
-  virtual string getOpcode() const = 0;
+  /// The predicate for CmpInst is defined by the subclasses but stored in 
+  /// the SubclassData field (see Value.h).  We allow it to be fetched here
+  /// as the predicate but there is no enum type for it, just the raw unsigned 
+  /// short. This facilitates comparison of CmpInst instances without delving
+  /// into the subclasses since predicate values are distinct between the
+  /// CmpInst subclasses.
+  /// @brief Return the predicate for this instruction.
+  unsigned short getPredicate() const {
+    return SubclassData;
+  }
 
-  virtual unsigned getNumOperands() const { return 2; }
-  virtual const Value *getOperand(unsigned i) const {
-    return (i == 0) ? Source1 : ((i == 1) ? Source2 : 0);
+  /// @brief Provide more efficient getOperand methods.
+  Value *getOperand(unsigned i) const {
+    assert(i < 2 && "getOperand() out of range!");
+    return Ops[i];
   }
-  inline Value *getOperand(unsigned i) {
-    return (i == 0) ? Source1 : ((i == 1) ? Source2 : 0);
+  void setOperand(unsigned i, Value *Val) {
+    assert(i < 2 && "setOperand() out of range!");
+    Ops[i] = Val;
   }
 
-  virtual bool setOperand(unsigned i, Value *Val) {
-    // assert(Val && "operand must not be null!");
-    if (i == 0) {
-      Source1 = Val; //assert(Val->getType() == Source2->getType());
-    } else if (i == 1) {
-      Source2 = Val; //assert(Val->getType() == Source1->getType());
-    } else {
-      return false;
-    }
-    return true;
+  /// @brief CmpInst instructions always have 2 operands.
+  unsigned getNumOperands() const { return 2; }
+
+  /// This is just a convenience that dispatches to the subclasses.
+  /// @brief Swap the operands and adjust predicate accordingly to retain
+  /// the same comparison.
+  void swapOperands();
+
+  /// This is just a convenience that dispatches to the subclasses.
+  /// @brief Determine if this CmpInst is commutative.
+  bool isCommutative();
+
+  /// This is just a convenience that dispatches to the subclasses.
+  /// @brief Determine if this is an equals/not equals predicate.
+  bool isEquality();
+
+  /// @returns true if the predicate is unsigned, false otherwise.
+  /// @brief Determine if the predicate is an unsigned operation.
+  static bool isUnsigned(unsigned short predicate);
+
+  /// @returns true if the predicate is signed, false otherwise.
+  /// @brief Determine if the predicate is an signed operation.
+  static bool isSigned(unsigned short predicate);
+
+  /// @brief Determine if the predicate is an ordered operation.
+  static bool isOrdered(unsigned short predicate);
+
+  /// @brief Determine if the predicate is an unordered operation.
+  static bool isUnordered(unsigned short predicate);
+
+  /// @brief Methods for support type inquiry through isa, cast, and dyn_cast:
+  static inline bool classof(const CmpInst *) { return true; }
+  static inline bool classof(const Instruction *I) {
+    return I->getOpcode() == Instruction::ICmp || 
+           I->getOpcode() == Instruction::FCmp;
+  }
+  static inline bool classof(const Value *V) {
+    return isa<Instruction>(V) && classof(cast<Instruction>(V));
   }
 };
 
+} // End llvm namespace
+
 #endif