- // Write out the data in buffer-sized blocks until the remainder
- // fits within the buffer.
- do {
- size_t NumBytes = OutBufEnd - OutBufCur;
- copy_to_buffer(Ptr, NumBytes);
- flush_nonempty();
- Ptr += NumBytes;
- Size -= NumBytes;
- } while (OutBufCur+Size > OutBufEnd);
+ size_t NumBytes = OutBufEnd - OutBufCur;
+
+ // If the buffer is empty at this point we have a string that is larger
+ // than the buffer. Directly write the chunk that is a multiple of the
+ // preferred buffer size and put the remainder in the buffer.
+ if (LLVM_UNLIKELY(OutBufCur == OutBufStart)) {
+ size_t BytesToWrite = Size - (Size % NumBytes);
+ write_impl(Ptr, BytesToWrite);
+ size_t BytesRemaining = Size - BytesToWrite;
+ if (BytesRemaining > size_t(OutBufEnd - OutBufCur)) {
+ // Too much left over to copy into our buffer.
+ return write(Ptr + BytesToWrite, BytesRemaining);
+ }
+ copy_to_buffer(Ptr + BytesToWrite, BytesRemaining);
+ return *this;
+ }
+
+ // We don't have enough space in the buffer to fit the string in. Insert as
+ // much as possible, flush and start over with the remainder.
+ copy_to_buffer(Ptr, NumBytes);
+ flush_nonempty();
+ return write(Ptr + NumBytes, Size - NumBytes);