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
67 const char *StrBegin, *StrEnd;
68 friend class LLVMContextImpl;
71 explicit MDString(const char *begin, const char *end)
72 : MetadataBase(Type::MetadataTy, Value::MDStringVal),
73 StrBegin(begin), StrEnd(end) {}
76 intptr_t size() const { return StrEnd - StrBegin; }
78 /// begin() - Pointer to the first byte of the string.
80 const char *begin() const { return StrBegin; }
82 /// end() - Pointer to one byte past the end of the string.
84 const char *end() const { return StrEnd; }
86 /// Methods for support type inquiry through isa, cast, and dyn_cast:
87 static inline bool classof(const MDString *) { return true; }
88 static bool classof(const Value *V) {
89 return V->getValueID() == MDStringVal;
93 //===----------------------------------------------------------------------===//
94 /// MDNode - a tuple of other values.
95 /// These contain a list of the values that represent the metadata.
97 class MDNode : public MetadataBase, public FoldingSetNode {
98 MDNode(const MDNode &); // DO NOT IMPLEMENT
100 friend class LLVMContextImpl;
102 void replaceElement(Value *From, Value *To);
104 SmallVector<WeakVH, 4> Node;
105 typedef SmallVectorImpl<WeakVH>::iterator elem_iterator;
108 explicit MDNode(Value*const* Vals, unsigned NumVals);
110 typedef SmallVectorImpl<WeakVH>::const_iterator const_elem_iterator;
112 Value *getElement(unsigned i) const {
116 unsigned getNumElements() const {
120 bool elem_empty() const {
124 const_elem_iterator elem_begin() const {
128 const_elem_iterator elem_end() const {
132 /// getType() specialization - Type is always MetadataTy.
134 inline const Type *getType() const {
135 return Type::MetadataTy;
138 /// isNullValue - Return true if this is the value that would be returned by
139 /// getNullValue. This always returns false because getNullValue will never
140 /// produce metadata.
141 virtual bool isNullValue() const {
145 /// Profile - calculate a unique identifier for this MDNode to collapse
147 void Profile(FoldingSetNodeID &ID) const;
149 virtual void replaceUsesOfWithOnConstant(Value *From, Value *To, Use *U) {
150 llvm_unreachable("This should never be called because MDNodes have no ops");
153 /// Methods for support type inquiry through isa, cast, and dyn_cast:
154 static inline bool classof(const MDNode *) { return true; }
155 static bool classof(const Value *V) {
156 return V->getValueID() == MDNodeVal;
160 } // end llvm namespace