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diff --git a/contrib/llvm/include/llvm/Support/BinaryStreamRef.h b/contrib/llvm/include/llvm/Support/BinaryStreamRef.h
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+++ b/contrib/llvm/include/llvm/Support/BinaryStreamRef.h
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+//===- BinaryStreamRef.h - A copyable reference to a stream -----*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_SUPPORT_BINARYSTREAMREF_H
+#define LLVM_SUPPORT_BINARYSTREAMREF_H
+
+#include "llvm/ADT/ArrayRef.h"
+#include "llvm/Support/BinaryStream.h"
+#include "llvm/Support/BinaryStreamError.h"
+#include "llvm/Support/Error.h"
+#include <algorithm>
+#include <cstdint>
+
+namespace llvm {
+
+/// Common stuff for mutable and immutable StreamRefs.
+template <class StreamType, class RefType> class BinaryStreamRefBase {
+public:
+  BinaryStreamRefBase() : Stream(nullptr), ViewOffset(0), Length(0) {}
+  BinaryStreamRefBase(StreamType &Stream, uint32_t Offset, uint32_t Length)
+      : Stream(&Stream), ViewOffset(Offset), Length(Length) {}
+
+  llvm::support::endianness getEndian() const { return Stream->getEndian(); }
+
+  uint32_t getLength() const { return Length; }
+  const StreamType *getStream() const { return Stream; }
+
+  /// Return a new BinaryStreamRef with the first \p N elements removed.
+  RefType drop_front(uint32_t N) const {
+    if (!Stream)
+      return RefType();
+
+    N = std::min(N, Length);
+    return RefType(*Stream, ViewOffset + N, Length - N);
+  }
+
+  /// Return a new BinaryStreamRef with only the first \p N elements remaining.
+  RefType keep_front(uint32_t N) const {
+    if (!Stream)
+      return RefType();
+    N = std::min(N, Length);
+    return RefType(*Stream, ViewOffset, N);
+  }
+
+  /// Return a new BinaryStreamRef with the first \p Offset elements removed,
+  /// and retaining exactly \p Len elements.
+  RefType slice(uint32_t Offset, uint32_t Len) const {
+    return drop_front(Offset).keep_front(Len);
+  }
+
+  bool operator==(const RefType &Other) const {
+    if (Stream != Other.Stream)
+      return false;
+    if (ViewOffset != Other.ViewOffset)
+      return false;
+    if (Length != Other.Length)
+      return false;
+    return true;
+  }
+
+protected:
+  Error checkOffset(uint32_t Offset, uint32_t DataSize) const {
+    if (Offset > getLength())
+      return make_error<BinaryStreamError>(stream_error_code::invalid_offset);
+    if (getLength() < DataSize + Offset)
+      return make_error<BinaryStreamError>(stream_error_code::stream_too_short);
+    return Error::success();
+  }
+
+  StreamType *Stream;
+  uint32_t ViewOffset;
+  uint32_t Length;
+};
+
+/// \brief BinaryStreamRef is to BinaryStream what ArrayRef is to an Array.  It
+/// provides copy-semantics and read only access to a "window" of the underlying
+/// BinaryStream. Note that BinaryStreamRef is *not* a BinaryStream.  That is to
+/// say, it does not inherit and override the methods of BinaryStream.  In
+/// general, you should not pass around pointers or references to BinaryStreams
+/// and use inheritance to achieve polymorphism.  Instead, you should pass
+/// around BinaryStreamRefs by value and achieve polymorphism that way.
+class BinaryStreamRef
+    : public BinaryStreamRefBase<BinaryStream, BinaryStreamRef> {
+public:
+  BinaryStreamRef() = default;
+  BinaryStreamRef(BinaryStream &Stream)
+      : BinaryStreamRefBase(Stream, 0, Stream.getLength()) {}
+  BinaryStreamRef(BinaryStream &Stream, uint32_t Offset, uint32_t Length)
+      : BinaryStreamRefBase(Stream, Offset, Length) {}
+
+  // Use BinaryStreamRef.slice() instead.
+  BinaryStreamRef(BinaryStreamRef &S, uint32_t Offset,
+                  uint32_t Length) = delete;
+
+  /// Given an Offset into this StreamRef and a Size, return a reference to a
+  /// buffer owned by the stream.
+  ///
+  /// \returns a success error code if the entire range of data is within the
+  /// bounds of this BinaryStreamRef's view and the implementation could read
+  /// the data, and an appropriate error code otherwise.
+  Error readBytes(uint32_t Offset, uint32_t Size,
+                  ArrayRef<uint8_t> &Buffer) const {
+    if (auto EC = checkOffset(Offset, Size))
+      return EC;
+
+    return Stream->readBytes(ViewOffset + Offset, Size, Buffer);
+  }
+
+  /// Given an Offset into this BinaryStreamRef, return a reference to the
+  /// largest buffer the stream could support without necessitating a copy.
+  ///
+  /// \returns a success error code if implementation could read the data,
+  /// and an appropriate error code otherwise.
+  Error readLongestContiguousChunk(uint32_t Offset,
+                                   ArrayRef<uint8_t> &Buffer) const {
+    if (auto EC = checkOffset(Offset, 1))
+      return EC;
+
+    if (auto EC =
+            Stream->readLongestContiguousChunk(ViewOffset + Offset, Buffer))
+      return EC;
+    // This StreamRef might refer to a smaller window over a larger stream.  In
+    // that case we will have read out more bytes than we should return, because
+    // we should not read past the end of the current view.
+    uint32_t MaxLength = Length - Offset;
+    if (Buffer.size() > MaxLength)
+      Buffer = Buffer.slice(0, MaxLength);
+    return Error::success();
+  }
+};
+
+class WritableBinaryStreamRef
+    : public BinaryStreamRefBase<WritableBinaryStream,
+                                 WritableBinaryStreamRef> {
+public:
+  WritableBinaryStreamRef() = default;
+  WritableBinaryStreamRef(WritableBinaryStream &Stream)
+      : BinaryStreamRefBase(Stream, 0, Stream.getLength()) {}
+  WritableBinaryStreamRef(WritableBinaryStream &Stream, uint32_t Offset,
+                          uint32_t Length)
+      : BinaryStreamRefBase(Stream, Offset, Length) {}
+
+  // Use WritableBinaryStreamRef.slice() instead.
+  WritableBinaryStreamRef(WritableBinaryStreamRef &S, uint32_t Offset,
+                          uint32_t Length) = delete;
+
+  /// Given an Offset into this WritableBinaryStreamRef and some input data,
+  /// writes the data to the underlying stream.
+  ///
+  /// \returns a success error code if the data could fit within the underlying
+  /// stream at the specified location and the implementation could write the
+  /// data, and an appropriate error code otherwise.
+  Error writeBytes(uint32_t Offset, ArrayRef<uint8_t> Data) const {
+    if (auto EC = checkOffset(Offset, Data.size()))
+      return EC;
+
+    return Stream->writeBytes(ViewOffset + Offset, Data);
+  }
+
+  operator BinaryStreamRef() { return BinaryStreamRef(*Stream); }
+
+  /// \brief For buffered streams, commits changes to the backing store.
+  Error commit() { return Stream->commit(); }
+};
+
+} // end namespace llvm
+
+#endif // LLVM_SUPPORT_BINARYSTREAMREF_H