llvm::RawMemoryObject handles empty ranges just fine, and the assert can
be triggered in the wild by e.g. invoking clang with a file that
included an empty pre-compiled header file when clang has been built
with assertions enabled. Without assertions enabled, clang will properly
report that the empty file is not a valid PCH.
llvm-svn: 158769
This CL delays reading of function bodies from initial parse until
materialization, allowing overlap of compilation with bitcode download.
llvm-svn: 149918