X-Git-Url: http://demsky.eecs.uci.edu/git/?a=blobdiff_plain;f=include%2Fllvm%2FConstant.h;h=7464dce3303fb0d0283120f969bdd66de4b03c03;hb=3a129c85920404e7ccdb7e655c89fa60a0309cfd;hp=36a26d7f25c32b476ab4b5f1497e7091efbc33ed;hpb=4a717d4a478ec40eb3b42078843af2291203ea21;p=oota-llvm.git diff --git a/include/llvm/Constant.h b/include/llvm/Constant.h index 36a26d7f25c..7464dce3303 100644 --- a/include/llvm/Constant.h +++ b/include/llvm/Constant.h @@ -1,4 +1,11 @@ -//===-- llvm/Constant.h - Constant class definition --------------*- C++ -*--=// +//===-- llvm/Constant.h - Constant class definition -------------*- C++ -*-===// +// +// The LLVM Compiler Infrastructure +// +// 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. // @@ -9,48 +16,143 @@ #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 &) LLVM_DELETED_FUNCTION; + Constant(const Constant &) LLVM_DELETED_FUNCTION; + virtual void anchor(); + protected: - inline Constant(const Type *Ty) : User(Ty, Value::ConstantVal) {} - ~Constant() {} - - // 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 - // constant. Any constants on our Use list must also be destroy'd. The - // implementation must be sure to remove the constant from the list of - // available cached constants. Implementations should call - // destroyConstantImpl as the last thing they do, to destroy all users and - // delete this. - // - virtual void destroyConstant() { assert(0 && "Not reached!"); } + Constant(Type *ty, ValueTy vty, Use *Ops, unsigned NumOps) + : User(ty, vty, Ops, NumOps) {} + void destroyConstantImpl(); public: - // Specialize setName to handle symbol table majik... - virtual void setName(const std::string &name, SymbolTable *ST = 0); + /// isNullValue - Return true if this is the value that would be returned by + /// getNullValue. + bool isNullValue() const; - // Static constructor to get a '0' constant of arbitrary type... - static Constant *getNullValue(const Type *Ty); + /// isAllOnesValue - Return true if this is the value that would be returned by + /// getAllOnesValue. + bool isAllOnesValue() const; - // isNullValue - Return true if this is the value that would be returned by - // getNullValue. - virtual bool isNullValue() const = 0; + /// isNegativeZeroValue - Return true if the value is what would be returned + /// by getZeroValueForNegation. + bool isNegativeZeroValue() const; - virtual void print(std::ostream &O) const; + /// 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; - // isConstantExpr - Return true if this is a ConstantExpr - virtual bool isConstantExpr() const { return false; } + /// 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 + }; - // Methods for support type inquiry through isa, cast, and dyn_cast: + /// 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; + + /// getAggregateElement - For aggregates (struct/array/vector) return the + /// constant that corresponds to the specified element if possible, or null if + /// not. This can return null if the element index is a ConstantExpr, or if + /// 'this' is a constant expr. + Constant *getAggregateElement(unsigned Elt) const; + Constant *getAggregateElement(Constant *Elt) 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 + /// constant. Any constants on our Use list must also be destroy'd. The + /// implementation must be sure to remove the constant from the list of + /// available cached constants. Implementations should call + /// destroyConstantImpl as the last thing they do, to destroy all users and + /// delete this. + virtual void destroyConstant() { llvm_unreachable("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 + /// User::replaceUsesOfWith (which does not work on constants) that does work + /// on constants. Basically this method goes through the trouble of building + /// a new constant that is equivalent to the current one, with all uses of + /// From replaced with uses of To. After this construction is completed, all + /// of the users of 'this' are replaced to use the new constant, and then + /// 'this' is deleted. In general, you should not call this method, instead, + /// use Value::replaceAllUsesWith, which automatically dispatches to this + /// method as needed. + /// + 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. + assert(getNumOperands() == 0 && "replaceUsesOfWithOnConstant must be " + "implemented for all constants that have operands!"); + llvm_unreachable("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. - virtual unsigned mutateReferences(Value* OldV, Value *NewV) { return 0; } - // END WARNING!! + static Constant *getNullValue(Type* Ty); + + /// @returns the value for an integer or vector of 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 + #endif