Comment # 11 on bug 99013 from Michel Dänzer

(In reply to Alexandre Demers from comment #9)
> If we rely on features included after the 3.9 release, shouldn't mesa check for
> 4.0.0svn (at least, beginning from 4c8c13b3)?

The commit you bisected to does that, grep for HAVE_LLVM. However, there was a
typo in the intrinsic name used with LLVM 3.9 and older.