UNITS_PER_SIMD_WORD

[H.J. Lu]

On Mon, Nov 1, 2010 at 9:27 AM, Paul Brook <paul@codesourcery.com> wrote:
>> Hi All,
>>
>> Is it possible to define UNITS_PER_SIMD_WORD as a global variable and
>> to set this varibale using a pragma (even once for a compilation) and
>> that way to be able to compile one file with UNITS_PER_SIMD_WORD = 8
>> and another file with UNITS_PER_SIMD_WORD = 16?
>
> No. This is an internal value that is a property of the vector ISA you're
> targeting.
>
> AFAIK there's only one supported target that supports variable length vectors
> (ARM NEON), which allows selecting between doubleword and quadword vectors via
> a target specific commandline option.  Idealy you wouldn't need this at all,
> but I don;t believe the vectorizer is capable of handling this.

x86 supports either 128bit (SSE) or 256bit (AVX) vectors. It works OK.



-- 
H.J.