vendor/clang/clang-trunk-r300422

1 files changed, 111 insertions, 0 deletions

diff --git a/include/clang/CodeGen/ConstantInitFuture.h b/include/clang/CodeGen/ConstantInitFuture.h
new file mode 100644
index 0000000000000..ef1a5d2f49af7
--- /dev/null
+++ b/include/clang/CodeGen/ConstantInitFuture.h
@@ -0,0 +1,111 @@
+//===- ConstantInitFuture.h - "Future" constant initializers ----*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This class defines the ConstantInitFuture class.  This is split out
+// from ConstantInitBuilder.h in order to allow APIs to work with it
+// without having to include that entire header.  This is particularly
+// important because it is often useful to be able to default-construct
+// a future in, say, a default argument.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CLANG_CODEGEN_CONSTANTINITFUTURE_H
+#define LLVM_CLANG_CODEGEN_CONSTANTINITFUTURE_H
+
+#include "llvm/ADT/PointerUnion.h"
+#include "llvm/IR/Constant.h"
+
+// Forward-declare ConstantInitBuilderBase and give it a
+// PointerLikeTypeTraits specialization so that we can safely use it
+// in a PointerUnion below.
+namespace clang {
+namespace CodeGen {
+class ConstantInitBuilderBase;
+}
+}
+namespace llvm {
+template <>
+class PointerLikeTypeTraits< ::clang::CodeGen::ConstantInitBuilderBase*> {
+public:
+  using T = ::clang::CodeGen::ConstantInitBuilderBase*;
+
+  static inline void *getAsVoidPointer(T p) { return p; }
+  static inline T getFromVoidPointer(void *p) {return static_cast<T>(p);}
+  enum { NumLowBitsAvailable = 2 };
+};
+}
+
+namespace clang {
+namespace CodeGen {
+
+/// A "future" for a completed constant initializer, which can be passed
+/// around independently of any sub-builders (but not the original parent).
+class ConstantInitFuture {
+  using PairTy = llvm::PointerUnion<ConstantInitBuilderBase*, llvm::Constant*>;
+
+  PairTy Data;
+
+  friend class ConstantInitBuilderBase;
+  explicit ConstantInitFuture(ConstantInitBuilderBase *builder);
+
+public:
+  ConstantInitFuture() {}
+
+  /// A future can be explicitly created from a fixed initializer.
+  explicit ConstantInitFuture(llvm::Constant *initializer) : Data(initializer) {
+    assert(initializer && "creating null future");
+  }
+
+  /// Is this future non-null?
+  explicit operator bool() const { return bool(Data); }
+
+  /// Return the type of the initializer.
+  llvm::Type *getType() const;
+
+  /// Abandon this initializer.
+  void abandon();
+
+  /// Install the initializer into a global variable.  This cannot
+  /// be called multiple times.
+  void installInGlobal(llvm::GlobalVariable *global);
+
+  void *getOpaqueValue() const { return Data.getOpaqueValue(); }
+  static ConstantInitFuture getFromOpaqueValue(void *value) {
+    ConstantInitFuture result;
+    result.Data = PairTy::getFromOpaqueValue(value);
+    return result;
+  }
+  enum {
+    NumLowBitsAvailable =
+      llvm::PointerLikeTypeTraits<PairTy>::NumLowBitsAvailable
+  };
+};
+
+}  // end namespace CodeGen
+}  // end namespace clang
+
+namespace llvm {
+
+template <>
+class PointerLikeTypeTraits< ::clang::CodeGen::ConstantInitFuture> {
+public:
+  using T = ::clang::CodeGen::ConstantInitFuture;
+
+  static inline void *getAsVoidPointer(T future) {
+    return future.getOpaqueValue();
+  }
+  static inline T getFromVoidPointer(void *p) {
+    return T::getFromOpaqueValue(p);
+  }
+  enum { NumLowBitsAvailable = T::NumLowBitsAvailable };
+};
+
+} // end namespace llvm
+
+#endif