X-Git-Url: http://demsky.eecs.uci.edu/git/?a=blobdiff_plain;f=include%2Fllvm%2FConstant.h;h=601b37bb64e4df165db1a12111b1d1d953de845f;hb=1360bc8eb029d51d426c77c4b1410849ff308893;hp=fbed6ee0fbf9d281a0a9c8427aebd53bb3987e00;hpb=d0fde30ce850b78371fd1386338350591f9ff494;p=oota-llvm.git diff --git a/include/llvm/Constant.h b/include/llvm/Constant.h index fbed6ee0fbf..601b37bb64e 100644 --- a/include/llvm/Constant.h +++ b/include/llvm/Constant.h @@ -1,10 +1,10 @@ //===-- llvm/Constant.h - Constant class definition -------------*- C++ -*-===// -// +// // The LLVM Compiler Infrastructure // -// This file was developed by the LLVM research group and is distributed under -// the University of Illinois Open Source License. See LICENSE.TXT for details. -// +// This file is distributed under the University of Illinois Open Source +// License. See LICENSE.TXT for details. +// //===----------------------------------------------------------------------===// // // This file contains the declaration of the Constant class. @@ -17,31 +17,80 @@ #include "llvm/User.h" namespace llvm { - + class APInt; + + template class SmallVectorImpl; + +/// This is an important base class in LLVM. It provides the common facilities +/// of all constant values in an LLVM program. A constant is a value that is +/// immutable at runtime. Functions are constants because their address is +/// immutable. Same with global variables. +/// +/// All constants share the capabilities provided in this class. All constants +/// can have a null value. They can have an operand list. Constants can be +/// simple (integer and floating point values), complex (arrays and structures), +/// or expression based (computations yielding a constant value composed of +/// only certain operators and other constant values). +/// +/// Note that Constants are immutable (once created they never change) +/// and are fully shared by structural equivalence. This means that two +/// structurally equivalent constants will always have the same address. +/// Constants are created on demand as needed and never deleted: thus clients +/// don't have to worry about the lifetime of the objects. +/// @brief LLVM Constant Representation class Constant : public User { + void operator=(const Constant &); // Do not implement + Constant(const Constant &); // Do not implement + protected: - inline Constant(const Type *Ty) : User(Ty, Value::ConstantVal) {} - ~Constant() {} + Constant(Type *ty, ValueTy vty, Use *Ops, unsigned NumOps) + : User(ty, vty, Ops, NumOps) {} void destroyConstantImpl(); public: - // setName - Specialize setName to handle symbol table majik... - virtual void setName(const std::string &name, SymbolTable *ST = 0); - - /// Static constructor to get a '0' constant of arbitrary type... - /// - static Constant *getNullValue(const Type *Ty); - /// isNullValue - Return true if this is the value that would be returned by /// getNullValue. - virtual bool isNullValue() const = 0; + bool isNullValue() const; - virtual void print(std::ostream &O) const; + /// isNegativeZeroValue - Return true if the value is what would be returned + /// by getZeroValueForNegation. + bool isNegativeZeroValue() const; - /// isConstantExpr - Return true if this is a ConstantExpr - /// - virtual bool isConstantExpr() const { return false; } + /// canTrap - Return true if evaluation of this constant could trap. This is + /// true for things like constant expressions that could divide by zero. + bool canTrap() const; + /// isConstantUsed - Return true if the constant has users other than constant + /// exprs and other dangling things. + bool isConstantUsed() const; + + enum PossibleRelocationsTy { + NoRelocation = 0, + LocalRelocation = 1, + GlobalRelocations = 2 + }; + + /// getRelocationInfo - This method classifies the entry according to + /// whether or not it may generate a relocation entry. This must be + /// conservative, so if it might codegen to a relocatable entry, it should say + /// so. The return values are: + /// + /// NoRelocation: This constant pool entry is guaranteed to never have a + /// relocation applied to it (because it holds a simple constant like + /// '4'). + /// LocalRelocation: This entry has relocations, but the entries are + /// guaranteed to be resolvable by the static linker, so the dynamic + /// linker will never see them. + /// GlobalRelocations: This entry may have arbitrary relocations. + /// + /// FIXME: This really should not be in VMCore. + PossibleRelocationsTy getRelocationInfo() const; + + /// getVectorElements - This method, which is only valid on constant of vector + /// type, returns the elements of the vector in the specified smallvector. + /// This handles breaking down a vector undef into undef elements, etc. For + /// constant exprs and other cases we can't handle, we return an empty vector. + void getVectorElements(SmallVectorImpl &Elts) const; /// destroyConstant - Called if some element of this constant is no longer /// valid. At this point only other constants may be on the use_list for this @@ -50,20 +99,14 @@ public: /// available cached constants. Implementations should call /// destroyConstantImpl as the last thing they do, to destroy all users and /// delete this. - /// - /// Note that this call is only valid on non-primitive constants: You cannot - /// destroy an integer constant for example. This API is used to delete - /// constants that have ConstantPointerRef's embeded in them when the module - /// is deleted, and it is used by GlobalDCE to remove ConstantPointerRefs that - /// are unneeded, allowing globals to be DCE'd. - /// virtual void destroyConstant() { assert(0 && "Not reached!"); } - //// Methods for support type inquiry through isa, cast, and dyn_cast: static inline bool classof(const Constant *) { return true; } + static inline bool classof(const GlobalValue *) { return true; } static inline bool classof(const Value *V) { - return V->getValueType() == Value::ConstantVal; + return V->getValueID() >= ConstantFirstVal && + V->getValueID() <= ConstantLastVal; } /// replaceUsesOfWithOnConstant - This method is a special form of @@ -76,8 +119,7 @@ public: /// use Value::replaceAllUsesWith, which automatically dispatches to this /// method as needed. /// - virtual void replaceUsesOfWithOnConstant(Value *From, Value *To, - bool DisableChecking = false) { + virtual void replaceUsesOfWithOnConstant(Value *, Value *, Use *) { // Provide a default implementation for constants (like integers) that // cannot use any other values. This cannot be called at runtime, but needs // to be here to avoid link errors. @@ -85,12 +127,23 @@ public: "implemented for all constants that have operands!"); assert(0 && "Constants that do not have operands cannot be using 'From'!"); } - - // WARNING: Only to be used by Bytecode & Assembly Parsers! USER CODE SHOULD - // NOT USE THIS!! - // Returns the number of uses of OldV that were replaced. - unsigned mutateReferences(Value* OldV, Value *NewV); - // END WARNING!! + + static Constant *getNullValue(Type* Ty); + + /// @returns the value for an integer constant of the given type that has all + /// its bits set to true. + /// @brief Get the all ones value + static Constant *getAllOnesValue(Type* Ty); + + /// getIntegerValue - Return the value for an integer or pointer constant, + /// or a vector thereof, with the given scalar value. + static Constant *getIntegerValue(Type* Ty, const APInt &V); + + /// removeDeadConstantUsers - If there are any dead constant users dangling + /// off of this constant, remove them. This method is useful for clients + /// that want to check to see if a global is unused, but don't want to deal + /// with potentially dead constants hanging off of the globals. + void removeDeadConstantUsers() const; }; } // End llvm namespace