[Insight-developers] Rounding and itkMath.h (Class vs Namespace)

[Tom Vercauteren]

>
> Indeed, the availability of these _mm_cvtss_si64 and _mm_cvtsd_si64
> intrinsics apparently depend on the compiler, compiler version, architecture
> and maybe more...
>
> I guess that we need to ad a try-compile to see whether we may use them or
> not. Another option would be to not use them and only implement the assembly
> versions.
>
>
>
> Is there any advantage to the intrinsics over the assembly?
>

 In theory, SSE2 intrinsics should depend only on the processor, not on the
compiler (as opposed to the assembly that depends on both). Hence, SSE2
should be more portable than the assembly. At least that was my experience
before dealing with these 64 bit intrinsics...

The performance difference between the two approaches did not seem
significant.

Tom
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