Re: [Qemu-devel] [RFC PATCH v2 1/3] target-arm: Use Neon for zero checking

[Peter Maydell]

On 9 April 2016 at 23:45, Richard Henderson <address@hidden> wrote:
> On 04/07/2016 02:58 AM, address@hidden wrote:
>>
>> +#elif defined __aarch64__
>> +#include "arm_neon.h"
>
>
> A better test is __NEON__, which asserts that neon is available at compile
> time (which will be true basically always for aarch64), and then you don't
> need a runime test for neon.

You don't need a runtime test for neon on aarch64 anyway, because
it will always be present.

> You also get support for armv7 with neon.

But if you do care about armv7 then you do need a runtime test,
because the defacto standard compile options are for armhf which
has FP but doesn't assume Neon.

Personally I think we should not worry about armv7 here, because
it's not actually a likely virtualization server platform, and
we shouldn't include code in QEMU we're not even compile testing.
So I think __aarch64__ here is fine.

thanks
-- PMM