Some questions about the /Qregcall option.

[CHENG__TOM]

Can the program I compiled with /Qregcall call functions in system DLL?

Calling Conventions of the system DLL is __cdecl or __stdcall.

Can the program compiled without /Qregcall call functions compiled with /Qregcall?

[Viet_H_Intel]

Please see https://software.intel.com/en-us/cpp-compiler-developer-guide-and-reference-regcall-qregcall for details.