PVS-Studio warning V642 for Firebird

SSHORT TextType::compare(ULONG len1, const UCHAR* str1,
                         ULONG len2, const UCHAR* str2)
{
  ....
  SSHORT cmp = memcmp(str1, str2, MIN(len1, len2));

  if (cmp == 0)
    cmp = (len1 < len2 ? -1 : (len1 > len2 ? 1 : 0));

  return cmp;

}

This suspicious code was found in Firebird project by PVS-Studio static code analyzer.
Warning message is:
V642 Saving the 'memcmp' function result inside the 'short' type variable is inappropriate. The significant bits could be lost breaking the program's logic. texttype.cpp 338

PVS-Studio is a static analyzer for detecting bugs in the source code of applications written in C, C++, C++11, C++/CX. Site: http://www.viva64.com/en/pvs-studio/