Summary: We need x86-64-specific builtins if we want to implement some of the MS intrinsics - winnt.h contains definitions of some functions for i386, but not for x86-64 (for example _InterlockedOr64), which means that we cannot treat them as builtins for both i386 and x86-64, because then we have definitions of builtin functions in winnt.h on i386.
Reviewers: thakis, majnemer, hans, rnk
Subscribers: cfe-commits
Differential Revision: https://reviews.llvm.org/D24598
llvm-svn: 283264