1) Why was MMX support removed from the compiler?
First release of EM64T compiler did work with MMX
and __m64. I doesn't matter if Microsoft is not supporting
__m64. Please enable it back, at least by an option!
EM64T supports MMX perfectly well, and in some cases
MMX code is faster than SSE, not to mention amount of
code currently in MMX intrinsics.
It is not inline 32-bit assembler!
If there are problems with MMX optimization in compiler,
it should be solved. Disabling support is not an option.
2) How can one call CPUID in 64-bit code?
It seems that intrinsic for this is not defined.
And since inline assembler is not available, there is no