Defaultify copy and move constructors for StreamRefs

[alex.telishev]

Summary

Only copy constructor was present for BinaryStreamRefBase and BinaryStreamRef resulting in move constructor being deleted. BinaryStreamRefBase contains std::shared_ptr that is quite expensive to copy and cheap to move. BinaryStreamRef is moved quite often (as it's used as return type of many functions).

[zturner]

lgtm, thanks! I'll commit this on your behalf.

llvm/include/llvm/Support/BinaryStreamRef.h

protected:
   BinaryStreamRefBase() = default;
   BinaryStreamRefBase(std::shared_ptr<StreamType> SharedImpl, uint32_t Offset,
                       uint32_t Length)
       : SharedImpl(SharedImpl), BorrowedImpl(SharedImpl.get()),
         ViewOffset(Offset), Length(Length) {}
   BinaryStreamRefBase(StreamType &BorrowedImpl, uint32_t Offset,
                       uint32_t Length)
       : BorrowedImpl(&BorrowedImpl), ViewOffset(Offset), Length(Length) {}
-  BinaryStreamRefBase(const BinaryStreamRefBase &Other) {
-    SharedImpl = Other.SharedImpl;
-    BorrowedImpl = Other.BorrowedImpl;
-    ViewOffset = Other.ViewOffset;
-    Length = Other.Length;
-  }
+  BinaryStreamRefBase(const BinaryStreamRefBase &Other) = default;
+  BinaryStreamRefBase &operator=(const BinaryStreamRefBase &Other) = default;
+
+  BinaryStreamRefBase &operator=(BinaryStreamRefBase &&Other) = default;
+  BinaryStreamRefBase(BinaryStreamRefBase &&Other) = default;
 
 public:
   llvm::support::endianness getEndian() const {
     return BorrowedImpl->getEndian();
   }
 
   uint32_t getLength() const { return Length; }
 

 public:
   BinaryStreamRef() = default;
   BinaryStreamRef(BinaryStream &Stream);
   BinaryStreamRef(BinaryStream &Stream, uint32_t Offset, uint32_t Length);
   explicit BinaryStreamRef(ArrayRef<uint8_t> Data,
                            llvm::support::endianness Endian);
   explicit BinaryStreamRef(StringRef Data, llvm::support::endianness Endian);
 
-  BinaryStreamRef(const BinaryStreamRef &Other);
+  BinaryStreamRef(const BinaryStreamRef &Other) = default;
+  BinaryStreamRef &operator=(const BinaryStreamRef &Other) = default;
+  BinaryStreamRef(BinaryStreamRef &&Other) = default;
+  BinaryStreamRef &operator=(BinaryStreamRef &&Other) = default;
 
   // 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.
   ///

 
 public:
   WritableBinaryStreamRef() = default;
   WritableBinaryStreamRef(WritableBinaryStream &Stream);
   WritableBinaryStreamRef(WritableBinaryStream &Stream, uint32_t Offset,
                           uint32_t Length);
   explicit WritableBinaryStreamRef(MutableArrayRef<uint8_t> Data,
                                    llvm::support::endianness Endian);
-  WritableBinaryStreamRef(const WritableBinaryStreamRef &Other);
+  WritableBinaryStreamRef(const WritableBinaryStreamRef &Other) = default;
+  WritableBinaryStreamRef &operator= (const WritableBinaryStreamRef &Other) = default;
+
+  WritableBinaryStreamRef(WritableBinaryStreamRef &&Other) = default;
+  WritableBinaryStreamRef &operator= (WritableBinaryStreamRef &&Other) = default;
 
   // 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.
   ///

llvm/lib/Support/BinaryStreamRef.cpp

BinaryStreamRef::BinaryStreamRef(BinaryStream &Stream, uint32_t Offset,
     : BinaryStreamRefBase(Stream, Offset, Length) {}
 BinaryStreamRef::BinaryStreamRef(ArrayRef<uint8_t> Data, endianness Endian)
     : BinaryStreamRefBase(std::make_shared<ArrayRefImpl>(Data, Endian), 0,
                           Data.size()) {}
 BinaryStreamRef::BinaryStreamRef(StringRef Data, endianness Endian)
     : BinaryStreamRef(makeArrayRef(Data.bytes_begin(), Data.bytes_end()),
                       Endian) {}
 
-BinaryStreamRef::BinaryStreamRef(const BinaryStreamRef &Other)
-    : BinaryStreamRefBase(Other) {}
-
 Error BinaryStreamRef::readBytes(uint32_t Offset, uint32_t Size,
                                  ArrayRef<uint8_t> &Buffer) const {
   if (auto EC = checkOffset(Offset, Size))
     return EC;
   return BorrowedImpl->readBytes(ViewOffset + Offset, Size, Buffer);
 }
 
 Error BinaryStreamRef::readLongestContiguousChunk(
WritableBinaryStreamRef::WritableBinaryStreamRef(WritableBinaryStream &Stream,
                                                  uint32_t Length)
     : BinaryStreamRefBase(Stream, Offset, Length) {}
 
 WritableBinaryStreamRef::WritableBinaryStreamRef(MutableArrayRef<uint8_t> Data,
                                                  endianness Endian)
     : BinaryStreamRefBase(std::make_shared<MutableArrayRefImpl>(Data, Endian),
                           0, Data.size()) {}
 
-WritableBinaryStreamRef::WritableBinaryStreamRef(
-    const WritableBinaryStreamRef &Other)
-    : BinaryStreamRefBase(Other) {}
 
 Error WritableBinaryStreamRef::writeBytes(uint32_t Offset,
                                           ArrayRef<uint8_t> Data) const {
   if (auto EC = checkOffset(Offset, Data.size()))
     return EC;
 
   return BorrowedImpl->writeBytes(ViewOffset + Offset, Data);
 }
 
 WritableBinaryStreamRef::operator BinaryStreamRef() const {
   return BinaryStreamRef(*BorrowedImpl, ViewOffset, Length);
 }
 
 /// \brief For buffered streams, commits changes to the backing store.
 Error WritableBinaryStreamRef::commit() { return BorrowedImpl->commit(); }