1 //===- ValueMapper.h - Remapping for constants and metadata -----*- C++ -*-===//
2 //
3 //                     The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 // This file defines the MapValue interface which is used by various parts of
11 // the Transforms/Utils library to implement cloning and linking facilities.
12 //
13 //===----------------------------------------------------------------------===//
14 
15 #ifndef LLVM_TRANSFORMS_UTILS_VALUEMAPPER_H
16 #define LLVM_TRANSFORMS_UTILS_VALUEMAPPER_H
17 
18 #include "llvm/IR/ValueMap.h"
19 
20 namespace llvm {
21   class Value;
22   class Instruction;
23   typedef ValueMap<const Value *, WeakVH> ValueToValueMapTy;
24 
25   /// ValueMapTypeRemapper - This is a class that can be implemented by clients
26   /// to remap types when cloning constants and instructions.
27   class ValueMapTypeRemapper {
28     virtual void anchor();  // Out of line method.
29   public:
~ValueMapTypeRemapper()30     virtual ~ValueMapTypeRemapper() {}
31 
32     /// remapType - The client should implement this method if they want to
33     /// remap types while mapping values.
34     virtual Type *remapType(Type *SrcTy) = 0;
35   };
36 
37   /// ValueMaterializer - This is a class that can be implemented by clients
38   /// to materialize Values on demand.
39   class ValueMaterializer {
40     virtual void anchor(); // Out of line method.
41 
42   protected:
43     ~ValueMaterializer() = default;
44     ValueMaterializer() = default;
45     ValueMaterializer(const ValueMaterializer&) = default;
46     ValueMaterializer &operator=(const ValueMaterializer&) = default;
47 
48   public:
49     /// The client should implement this method if they want to generate a
50     /// mapped Value on demand. For example, if linking lazily.
51     virtual Value *materializeDeclFor(Value *V) = 0;
52 
53     /// If the data being mapped is recursive, the above function can map
54     /// just the declaration and this is called to compute the initializer.
55     /// It is called after the mapping is recorded, so it doesn't need to worry
56     /// about recursion.
57     virtual void materializeInitFor(GlobalValue *New, GlobalValue *Old);
58 
59     /// If the client needs to handle temporary metadata it must implement
60     /// these methods.
mapTemporaryMetadata(Metadata * MD)61     virtual Metadata *mapTemporaryMetadata(Metadata *MD) { return nullptr; }
replaceTemporaryMetadata(const Metadata * OrigMD,Metadata * NewMD)62     virtual void replaceTemporaryMetadata(const Metadata *OrigMD,
63                                           Metadata *NewMD) {}
64 
65     /// The client should implement this method if some metadata need
66     /// not be mapped, for example DISubprogram metadata for functions not
67     /// linked into the destination module.
isMetadataNeeded(Metadata * MD)68     virtual bool isMetadataNeeded(Metadata *MD) { return true; }
69   };
70 
71   /// RemapFlags - These are flags that the value mapping APIs allow.
72   enum RemapFlags {
73     RF_None = 0,
74 
75     /// RF_NoModuleLevelChanges - If this flag is set, the remapper knows that
76     /// only local values within a function (such as an instruction or argument)
77     /// are mapped, not global values like functions and global metadata.
78     RF_NoModuleLevelChanges = 1,
79 
80     /// RF_IgnoreMissingEntries - If this flag is set, the remapper ignores
81     /// entries that are not in the value map.  If it is unset, it aborts if an
82     /// operand is asked to be remapped which doesn't exist in the mapping.
83     RF_IgnoreMissingEntries = 2,
84 
85     /// Instruct the remapper to move distinct metadata instead of duplicating
86     /// it when there are module-level changes.
87     RF_MoveDistinctMDs = 4,
88 
89     /// Any global values not in value map are mapped to null instead of
90     /// mapping to self. Illegal if RF_IgnoreMissingEntries is also set.
91     RF_NullMapMissingGlobalValues = 8,
92 
93     /// Set when there is still temporary metadata that must be handled,
94     /// such as when we are doing function importing and will materialize
95     /// and link metadata as a postpass.
96     RF_HaveUnmaterializedMetadata = 16,
97   };
98 
99   static inline RemapFlags operator|(RemapFlags LHS, RemapFlags RHS) {
100     return RemapFlags(unsigned(LHS)|unsigned(RHS));
101   }
102 
103   Value *MapValue(const Value *V, ValueToValueMapTy &VM,
104                   RemapFlags Flags = RF_None,
105                   ValueMapTypeRemapper *TypeMapper = nullptr,
106                   ValueMaterializer *Materializer = nullptr);
107 
108   Metadata *MapMetadata(const Metadata *MD, ValueToValueMapTy &VM,
109                         RemapFlags Flags = RF_None,
110                         ValueMapTypeRemapper *TypeMapper = nullptr,
111                         ValueMaterializer *Materializer = nullptr);
112 
113   /// MapMetadata - provide versions that preserve type safety for MDNodes.
114   MDNode *MapMetadata(const MDNode *MD, ValueToValueMapTy &VM,
115                       RemapFlags Flags = RF_None,
116                       ValueMapTypeRemapper *TypeMapper = nullptr,
117                       ValueMaterializer *Materializer = nullptr);
118 
119   void RemapInstruction(Instruction *I, ValueToValueMapTy &VM,
120                         RemapFlags Flags = RF_None,
121                         ValueMapTypeRemapper *TypeMapper = nullptr,
122                         ValueMaterializer *Materializer = nullptr);
123 
124   /// MapValue - provide versions that preserve type safety for Constants.
125   inline Constant *MapValue(const Constant *V, ValueToValueMapTy &VM,
126                             RemapFlags Flags = RF_None,
127                             ValueMapTypeRemapper *TypeMapper = nullptr,
128                             ValueMaterializer *Materializer = nullptr) {
129     return cast<Constant>(MapValue((const Value*)V, VM, Flags, TypeMapper,
130                                    Materializer));
131   }
132 
133 } // End llvm namespace
134 
135 #endif
136