X-Git-Url: http://demsky.eecs.uci.edu/git/?a=blobdiff_plain;f=include%2Fllvm%2FConstant.h;h=62b75a77fb395a41ead25232165169282cbcde8d;hb=a3af370dc12f6d5100da5d614ab0a62da135569a;hp=572d1d15ca92761ed20796f9796a8585c2f43e9f;hpb=31bcdb822fe9133b1973de51519d34e5813a6184;p=oota-llvm.git diff --git a/include/llvm/Constant.h b/include/llvm/Constant.h index 572d1d15ca9..62b75a77fb3 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. // @@ -9,39 +16,125 @@ #include "llvm/User.h" +namespace llvm { + template class SmallVectorImpl; + class LLVMContext; + + /// If object contains references to other objects, then relocations are + /// usually required for emission of such object (especially in PIC mode). One + /// usually distinguishes local and global relocations. Local relocations are + /// made wrt objects in the same module and these objects have local (internal + /// or private) linkage. Global relocations are made wrt externally visible + /// objects. In most cases local relocations can be resolved via so-called + /// 'pre-link' technique. + namespace Reloc { + const unsigned None = 0; + const unsigned Local = 1 << 0; ///< Local relocations are required + const unsigned Global = 1 << 1; ///< Global relocations are required + const unsigned LocalOrGlobal = Local | Global; + } + +/// 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() {} - - // 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(const 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. + virtual bool isNullValue() const = 0; - // Static constructor to get a '0' constant of arbitrary type... - static Constant *getNullValue(const Type *Ty); + /// isNegativeZeroValue - Return true if the value is what would be returned + /// by getZeroValueForNegation. + virtual bool isNegativeZeroValue() const { return isNullValue(); } - // isNullValue - Return true if this is the value that would be returned by - // getNullValue. - virtual bool isNullValue() const = 0; + /// 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; + + /// ContainsRelocations - Return true if the constant value contains + /// relocations which cannot be resolved at compile time. Note that answer is + /// not exclusive: there can be possibility that relocations of other kind are + /// required as well. + bool ContainsRelocations(unsigned Kind = Reloc::LocalOrGlobal) const; + + // Specialize get/setOperand for Constants as their operands are always + // constants as well. + Constant *getOperand(unsigned i) { + return static_cast(User::getOperand(i)); + } + const Constant *getOperand(unsigned i) const { + return static_cast(User::getOperand(i)); + } + void setOperand(unsigned i, Constant *C) { + User::setOperand(i, C); + } + + /// 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(LLVMContext &Context, + SmallVectorImpl &Elts) const; - virtual void print(std::ostream &O) 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() { assert(0 && "Not reached!"); } - // Methods for support type inquiry through isa, cast, and dyn_cast: + //// 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!"); + assert(0 && "Constants that do not have operands cannot be using 'From'!"); } }; +} // End llvm namespace + #endif