don't explode if the offset we get is zero. This can happen if
you have an empty virtual base class.
While I'm at it, remove an unnecessary block from the IR-generation
of the null-check, mark the eventual GEP as inbounds, and generally
prettify.
llvm-svn: 161100
non-class prvalues actually require the realization of a
temporary. For everything else, we already have an lvalue (or class
prvalue) in the subexpression.
Note: we're missing some move elision in this case. I'll tackle that next.
llvm-svn: 124453
