[MS] Fix __movs intrinsics

[rnk]

Summary

These were incorrectly updated in r290539.

[ahatanak]

The changes in intrin.h look good.

Is it possible to add a test?

[dolson]

Not a reviewer, but Re: https://reviews.llvm.org/D15075#940711 the changes in this review are identical to the ones I made locally yesterday and they resolved my problem with bad code generation. TYVM

[rnk]

In D40686#941640, @ahatanak wrote:

The changes in intrin.h look good.

Is it possible to add a test?

The only meaningful test is an assembly generation test, so we'd have to bend the rules of the clang test suite. An IR test wouldn't be meaningful. I think it's worth bending the rules, and if you do too I'll add it.

[ahatanak]

I agree that the test should check the assembly instructions emitted are valid, so an assembly test makes sense.

clang/lib/Headers/intrin.h

 #endif
 
 /*----------------------------------------------------------------------------*\
 |* movs, stos
 \*----------------------------------------------------------------------------*/
 #if defined(__i386__) || defined(__x86_64__)
 static __inline__ void __DEFAULT_FN_ATTRS
 __movsb(unsigned char *__dst, unsigned char const *__src, size_t __n) {
-  __asm__("rep movsb" : : "D"(__dst), "S"(__src), "c"(__n));
+  __asm__("rep movsb" : "+D"(__dst), "+S"(__src), "+c"(__n) : : "memory");
 }
 static __inline__ void __DEFAULT_FN_ATTRS
 __movsd(unsigned long *__dst, unsigned long const *__src, size_t __n) {
-  __asm__("rep movsl" : : "D"(__dst), "S"(__src), "c"(__n));
+  __asm__("rep movsl" : "+D"(__dst), "+S"(__src), "+c"(__n) : : "memory");
 }
 static __inline__ void __DEFAULT_FN_ATTRS
 __movsw(unsigned short *__dst, unsigned short const *__src, size_t __n) {
-  __asm__("rep movsw" : : "D"(__dst), "S"(__src), "c"(__n));
+  __asm__("rep movsw" : "+D"(__dst), "+S"(__src), "+c"(__n) : : "memory");
 }
 static __inline__ void __DEFAULT_FN_ATTRS
 __stosd(unsigned long *__dst, unsigned long __x, size_t __n) {
-  __asm__("rep stosl" : : "D"(__dst), "a"(__x), "c"(__n));
+  __asm__("rep stosl" : "+D"(__dst), "+c"(__n) : "a"(__x) : "memory");
 }
 static __inline__ void __DEFAULT_FN_ATTRS
 __stosw(unsigned short *__dst, unsigned short __x, size_t __n) {
-  __asm__("rep stosw" : : "D"(__dst), "a"(__x), "c"(__n));
+  __asm__("rep stosw" : "+D"(__dst), "+c"(__n) : "a"(__x) : "memory");
 }
 #endif
 #ifdef __x86_64__
 static __inline__ void __DEFAULT_FN_ATTRS
 __movsq(unsigned long long *__dst, unsigned long long const *__src, size_t __n) {
-  __asm__("rep movsq" : : "D"(__dst), "S"(__src), "c"(__n));
+  __asm__("rep movsq" : "+D"(__dst), "+S"(__src), "+c"(__n) : : "memory");
 }
 static __inline__ void __DEFAULT_FN_ATTRS
 __stosq(unsigned __int64 *__dst, unsigned __int64 __x, size_t __n) {
-  __asm__("rep stosq" : : "D"(__dst), "a"(__x), "c"(__n));
+  __asm__("rep stosq" : "+D"(__dst), "+c"(__n) : "a"(__x) : "memory");
 }
 #endif
 
 /*----------------------------------------------------------------------------*\
 |* Misc
 \*----------------------------------------------------------------------------*/
 #if defined(__i386__) || defined(__x86_64__)
 static __inline__ void __DEFAULT_FN_ATTRS