Add MS __nop intrinsic to intrin.h

Summary: There was no definition for __nop function - added inline
assembly.

Patch by Albert Gutowski!

Reviewers: rnk, thakis

Subscribers: cfe-commits

Differential Revision: https://reviews.llvm.org/D24286

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@280826 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Headers/intrin.h

@@ -97,6 +97,7 @@ static __inline__
 void __movsd(unsigned long *, unsigned long const *, size_t);
 static __inline__
 void __movsw(unsigned short *, unsigned short const *, size_t);
+static __inline__
 void __nop(void);
 void __nvreg_restore_fence(void);
 void __nvreg_save_fence(void);
@@ -918,6 +919,10 @@ static __inline__ void __DEFAULT_FN_ATTRS
 __halt(void) {
   __asm__ volatile ("hlt");
 }
+static __inline__ void __DEFAULT_FN_ATTRS
+__nop(void) {
+  __asm__ volatile ("nop");
+}
 #endif
 
 /*----------------------------------------------------------------------------*\

test/Headers/ms-intrin.cpp

@@ -52,6 +52,7 @@ void f() {
   __cpuidex(info, 0, 0);
   _xgetbv(0);
   __halt();
+  __nop();
   __readmsr(0);
 
   // FIXME: Call these in 64-bit too once the intrinsics have been fixed to