1 files changed, 49 insertions, 0 deletions
diff --git a/include/llvm/Support/SaveAndRestore.h b/include/llvm/Support/SaveAndRestore.h
new file mode 100644
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+++ b/include/llvm/Support/SaveAndRestore.h
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+//===-- SaveAndRestore.h - Utility  -------------------------------*- C++ -*-=//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+///
+/// \file
+/// This file provides utility classes that use RAII to save and restore
+/// values.
+///
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_SUPPORT_SAVEANDRESTORE_H
+#define LLVM_SUPPORT_SAVEANDRESTORE_H
+
+namespace llvm {
+
+/// A utility class that uses RAII to save and restore the value of a variable.
+template <typename T> struct SaveAndRestore {
+  SaveAndRestore(T &X) : X(X), OldValue(X) {}
+  SaveAndRestore(T &X, const T &NewValue) : X(X), OldValue(X) {
+    X = NewValue;
+  }
+  ~SaveAndRestore() { X = OldValue; }
+  T get() { return OldValue; }
+
+private:
+  T &X;
+  T OldValue;
+};
+
+/// Similar to \c SaveAndRestore.  Operates only on bools; the old value of a
+/// variable is saved, and during the dstor the old value is or'ed with the new
+/// value.
+struct SaveOr {
+  SaveOr(bool &X) : X(X), OldValue(X) { X = false; }
+  ~SaveOr() { X |= OldValue; }
+
+private:
+  bool &X;
+  const bool OldValue;
+};
+
+} // namespace llvm
+
+#endif