1 //===-- llvm/Metadata.h - Constant class subclass definitions ---*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
11 /// This file contains the declarations for the subclasses of Constant,
12 /// which represent the different flavors of constant values that live in LLVM.
13 /// Note that Constants are immutable (once created they never change) and are
14 /// fully shared by structural equivalence. This means that two structurally
15 /// equivalent constants will always have the same address. Constant's are
16 /// created on demand as needed and never deleted: thus clients don't have to
17 /// worry about the lifetime of the objects.
19 //===----------------------------------------------------------------------===//
24 #include "llvm/Constant.h"
25 #include "llvm/Type.h"
26 #include "llvm/ADT/FoldingSet.h"
27 #include "llvm/ADT/SmallVector.h"
28 #include "llvm/Support/ErrorHandling.h"
29 #include "llvm/Support/ValueHandle.h"
33 //===----------------------------------------------------------------------===//
34 // MetadataBase - A base class for MDNode and MDString.
35 class MetadataBase : public Value {
37 MetadataBase(const Type *Ty, unsigned scid)
41 /// getType() specialization - Type is always MetadataTy.
43 inline const Type *getType() const {
44 return Type::MetadataTy;
47 /// isNullValue - Return true if this is the value that would be returned by
48 /// getNullValue. This always returns false because getNullValue will never
50 virtual bool isNullValue() const {
54 /// Methods for support type inquiry through isa, cast, and dyn_cast:
55 static inline bool classof(const MDString *) { return true; }
56 static bool classof(const Value *V) {
57 return V->getValueID() == MDStringVal || V->getValueID() == MDNodeVal;
61 //===----------------------------------------------------------------------===//
62 /// MDString - a single uniqued string.
63 /// These are used to efficiently contain a byte sequence for metadata.
65 class MDString : public MetadataBase {
66 MDString(const MDString &); // DO NOT IMPLEMENT
68 friend class LLVMContextImpl;
71 explicit MDString(const char *begin, unsigned l)
72 : MetadataBase(Type::MetadataTy, Value::MDStringVal), Str(begin, l) {}
75 StringRef getString() const { return Str; }
77 unsigned length() const { return Str.size(); }
79 /// begin() - Pointer to the first byte of the string.
81 const char *begin() const { return Str.begin(); }
83 /// end() - Pointer to one byte past the end of the string.
85 const char *end() const { return Str.end(); }
87 /// Methods for support type inquiry through isa, cast, and dyn_cast:
88 static inline bool classof(const MDString *) { return true; }
89 static bool classof(const Value *V) {
90 return V->getValueID() == MDStringVal;
94 //===----------------------------------------------------------------------===//
95 /// MDNode - a tuple of other values.
96 /// These contain a list of the values that represent the metadata.
98 class MDNode : public MetadataBase, public FoldingSetNode {
99 MDNode(const MDNode &); // DO NOT IMPLEMENT
101 friend class LLVMContextImpl;
103 void replaceElement(Value *From, Value *To);
105 SmallVector<WeakVH, 4> Node;
106 typedef SmallVectorImpl<WeakVH>::iterator elem_iterator;
109 explicit MDNode(Value*const* Vals, unsigned NumVals);
111 typedef SmallVectorImpl<WeakVH>::const_iterator const_elem_iterator;
113 Value *getElement(unsigned i) const {
117 unsigned getNumElements() const {
121 bool elem_empty() const {
125 const_elem_iterator elem_begin() const {
129 const_elem_iterator elem_end() const {
133 /// getType() specialization - Type is always MetadataTy.
135 inline const Type *getType() const {
136 return Type::MetadataTy;
139 /// isNullValue - Return true if this is the value that would be returned by
140 /// getNullValue. This always returns false because getNullValue will never
141 /// produce metadata.
142 virtual bool isNullValue() const {
146 /// Profile - calculate a unique identifier for this MDNode to collapse
148 void Profile(FoldingSetNodeID &ID) const;
150 virtual void replaceUsesOfWithOnConstant(Value *From, Value *To, Use *U) {
151 llvm_unreachable("This should never be called because MDNodes have no ops");
154 /// Methods for support type inquiry through isa, cast, and dyn_cast:
155 static inline bool classof(const MDNode *) { return true; }
156 static bool classof(const Value *V) {
157 return V->getValueID() == MDNodeVal;
161 } // end llvm namespace