clang  9.0.0svn
ConstantInitFuture.h
Go to the documentation of this file.
1 //===- ConstantInitFuture.h - "Future" constant initializers ----*- C++ -*-===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // This class defines the ConstantInitFuture class. This is split out
10 // from ConstantInitBuilder.h in order to allow APIs to work with it
11 // without having to include that entire header. This is particularly
12 // important because it is often useful to be able to default-construct
13 // a future in, say, a default argument.
14 //
15 //===----------------------------------------------------------------------===//
16 
17 #ifndef LLVM_CLANG_CODEGEN_CONSTANTINITFUTURE_H
18 #define LLVM_CLANG_CODEGEN_CONSTANTINITFUTURE_H
19 
20 #include "llvm/ADT/PointerUnion.h"
21 #include "llvm/IR/Constant.h"
22 
23 // Forward-declare ConstantInitBuilderBase and give it a
24 // PointerLikeTypeTraits specialization so that we can safely use it
25 // in a PointerUnion below.
26 namespace clang {
27 namespace CodeGen {
28 class ConstantInitBuilderBase;
29 }
30 }
31 namespace llvm {
32 template <>
35 
36  static inline void *getAsVoidPointer(T p) { return p; }
37  static inline T getFromVoidPointer(void *p) {return static_cast<T>(p);}
38  enum { NumLowBitsAvailable = 2 };
39 };
40 }
41 
42 namespace clang {
43 namespace CodeGen {
44 
45 /// A "future" for a completed constant initializer, which can be passed
46 /// around independently of any sub-builders (but not the original parent).
48  using PairTy = llvm::PointerUnion<ConstantInitBuilderBase*, llvm::Constant*>;
49 
50  PairTy Data;
51 
54 
55 public:
57 
58  /// A future can be explicitly created from a fixed initializer.
59  explicit ConstantInitFuture(llvm::Constant *initializer) : Data(initializer) {
60  assert(initializer && "creating null future");
61  }
62 
63  /// Is this future non-null?
64  explicit operator bool() const { return bool(Data); }
65 
66  /// Return the type of the initializer.
67  llvm::Type *getType() const;
68 
69  /// Abandon this initializer.
70  void abandon();
71 
72  /// Install the initializer into a global variable. This cannot
73  /// be called multiple times.
74  void installInGlobal(llvm::GlobalVariable *global);
75 
76  void *getOpaqueValue() const { return Data.getOpaqueValue(); }
77  static ConstantInitFuture getFromOpaqueValue(void *value) {
78  ConstantInitFuture result;
79  result.Data = PairTy::getFromOpaqueValue(value);
80  return result;
81  }
82  enum {
83  NumLowBitsAvailable =
85  };
86 };
87 
88 } // end namespace CodeGen
89 } // end namespace clang
90 
91 namespace llvm {
92 
93 template <>
96 
97  static inline void *getAsVoidPointer(T future) {
98  return future.getOpaqueValue();
99  }
100  static inline T getFromVoidPointer(void *p) {
101  return T::getFromOpaqueValue(p);
102  }
103  enum { NumLowBitsAvailable = T::NumLowBitsAvailable };
104 };
105 
106 } // end namespace llvm
107 
108 #endif
DominatorTree GraphTraits specialization so the DominatorTree can be iterable by generic graph iterat...
Definition: Dominators.h:29
#define bool
Definition: stdbool.h:15
The l-value was considered opaque, so the alignment was determined from a type.
ConstantInitFuture(llvm::Constant *initializer)
A future can be explicitly created from a fixed initializer.
A "future" for a completed constant initializer, which can be passed around independently of any sub-...
Dataflow Directional Tag Classes.
static ConstantInitFuture getFromOpaqueValue(void *value)