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//===-- llvm/Metadata.h - Constant class subclass definitions ---*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
/// @file
/// This file contains the declarations for the subclasses of Constant,
/// which represent the different flavors of constant values that live in LLVM.
/// 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. Constant's are
/// created on demand as needed and never deleted: thus clients don't have to
/// worry about the lifetime of the objects.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_MDNODE_H
#define LLVM_MDNODE_H
#include "llvm/Constant.h"
#include "llvm/Type.h"
#include "llvm/ADT/FoldingSet.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/ValueHandle.h"
namespace llvm {
//===----------------------------------------------------------------------===//
// MetadataBase - A base class for MDNode and MDString.
class MetadataBase : public Value {
public:
MetadataBase(const Type *Ty, unsigned scid)
: Value(Ty, scid) {}
/// getType() specialization - Type is always MetadataTy.
///
inline const Type *getType() const {
return Type::MetadataTy;
}
/// isNullValue - Return true if this is the value that would be returned by
/// getNullValue. This always returns false because getNullValue will never
/// produce metadata.
virtual bool isNullValue() const {
return false;
}
/// Methods for support type inquiry through isa, cast, and dyn_cast:
static inline bool classof(const MDString *) { return true; }
static bool classof(const Value *V) {
return V->getValueID() == MDStringVal;
}
};
//===----------------------------------------------------------------------===//
/// MDString - a single uniqued string.
/// These are used to efficiently contain a byte sequence for metadata.
///
class MDString : public MetadataBase {
MDString(const MDString &); // DO NOT IMPLEMENT
const char *StrBegin, *StrEnd;
friend class LLVMContextImpl;
public:
MDString(const char *begin, const char *end)
: MetadataBase(Type::MetadataTy, Value::MDStringVal),
StrBegin(begin), StrEnd(end) {}
intptr_t size() const { return StrEnd - StrBegin; }
/// begin() - Pointer to the first byte of the string.
///
const char *begin() const { return StrBegin; }
/// end() - Pointer to one byte past the end of the string.
///
const char *end() const { return StrEnd; }
/// Methods for support type inquiry through isa, cast, and dyn_cast:
static inline bool classof(const MDString *) { return true; }
static bool classof(const Value *V) {
return V->getValueID() == MDStringVal;
}
};
//===----------------------------------------------------------------------===//
/// MDNode - a tuple of other values.
/// These contain a list of the Constants that represent the metadata. The
/// operand list is always empty, query the element list instead.
///
/// This class will attempt to keep track of values as they are modified. When
/// a value is replaced the element will be replaced with it, and when the
/// value is deleted the element is set to a null pointer. In order to preserve
/// structural equivalence while the elements mutate, the MDNode may call
/// replaceAllUsesWith on itself. Because of this, users of MDNode must use a
/// WeakVH or CallbackVH to hold the node pointer if there is a chance that one
/// of the elements held by the node may change.
///
class MDNode : public Constant, public FoldingSetNode {
MDNode(const MDNode &); // DO NOT IMPLEMENT
friend class LLVMContextImpl;
friend class ElementVH;
struct ElementVH : public CallbackVH {
MDNode *OwningNode;
ElementVH(Value *V, MDNode *Parent)
: CallbackVH(V), OwningNode(Parent) {}
~ElementVH() {}
/// deleted - Set this entry in the MDNode to 'null'. This will reallocate
/// the MDNode.
virtual void deleted() {
OwningNode->replaceElement(this->operator Value*(), 0);
}
/// allUsesReplacedWith - Modify the MDNode by replacing this entry with
/// new_value. This will reallocate the MDNode.
virtual void allUsesReplacedWith(Value *new_value) {
OwningNode->replaceElement(this->operator Value*(), new_value);
}
};
void replaceElement(Value *From, Value *To);
SmallVector<ElementVH, 4> Node;
typedef SmallVectorImpl<ElementVH>::iterator elem_iterator;
protected:
explicit MDNode(Value*const* Vals, unsigned NumVals);
public:
typedef SmallVectorImpl<ElementVH>::const_iterator const_elem_iterator;
Value *getElement(unsigned i) const {
return Node[i];
}
unsigned getNumElements() const {
return Node.size();
}
bool elem_empty() const {
return Node.empty();
}
const_elem_iterator elem_begin() const {
return Node.begin();
}
const_elem_iterator elem_end() const {
return Node.end();
}
/// getType() specialization - Type is always MetadataTy.
///
inline const Type *getType() const {
return Type::MetadataTy;
}
/// isNullValue - Return true if this is the value that would be returned by
/// getNullValue. This always returns false because getNullValue will never
/// produce metadata.
virtual bool isNullValue() const {
return false;
}
/// Profile - calculate a unique identifier for this MDNode to collapse
/// duplicates
void Profile(FoldingSetNodeID &ID) const;
virtual void destroyConstant();
virtual void replaceUsesOfWithOnConstant(Value *From, Value *To, Use *U) {
llvm_unreachable("This should never be called because MDNodes have no ops");
}
/// Methods for support type inquiry through isa, cast, and dyn_cast:
static inline bool classof(const MDNode *) { return true; }
static bool classof(const Value *V) {
return V->getValueID() == MDNodeVal;
}
};
} // end llvm namespace
#endif
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