__umulh, __mulh, _addcarry_u32, and _addcarry_u64

[perdrix52]

Background: The Qt framework (in qnumeric.h) includes <intrin.h> when compiling with MSVC. This header is included if any code uses any Qt classes. Unfortunately this breaks simde with lots of errors about redefinitions.

Does simde provide a header that defines these intrinsics in a portable manner such that I could modify their header to read e.g.

#if __has_include("simde-xxxxx.h")
#include "simde-xxxxx.h"
#else
#include <intrin.h>
#endif

[mr-c]

Hello @perdrix52 , SIMDe does not yet have implementations for __umulh, __mulh, _addcarry_u32, and _addcarry_u64. I would be happy to review such a contribution.

Can you share more about the errors you are seeing?