On 6 March 2018 at 18:53, Jens Axboe <axboe@xxxxxxxxx> wrote:
> On 3/6/18 11:45 AM, Sitsofe Wheeler wrote:
>> [...]
>>> +##########################################
>>> +# sse probe
>>> +sse="no"
>>> +cat > $TMPC << EOF
>>> +#include <xmmintrin.h>
>>> +#include <immintrin.h>
>>> +int main(int argc, char **argv)
>>> +{
>>> + __m128 val;
>>> + float const *src = NULL;
>>> + float *dst = NULL;
>>> + val = _mm_load_ps(src);
>>> + _mm_store_ps(dst, val);
>>> + return 0;
>>> +}
>>
>> We could try and use __builtin_ia32_addps (from
>> https://gcc.gnu.org/onlinedocs/gcc/x86-Built-in-Functions.html#x86-Built-in-Functions
>
> Sure
>
>>> +EOF
>>> +if test "$enable_sse" = "yes" && compile_prog "-msse" "" "sse"; then
>>> + sse="yes"
>>> +fi
>>> +print_config "SSE (compiler)" "$sse"
>>
>> Here we wouldn't explicitly add -msse because we would have already
>> added it to the global CFLAGS if forced or depended on the user's
>> particular compiler flags if not.
>
> It's only enabled IFF the global flag (--enable-sse) is set AND the
> configure test passes.
Right and I'm saying change the how we add the flag and the configure
test. If the user explicitly sets sse on the configure line then
assume the user knows what they're doing and add it to the CFLAGS and
but always detect (via comping a program that would only work if the
user really had told the compiler to use SSE) if its already enabled
later (rather than only if the user turned it on). My thinking is that
platforms like x86_64 will nearly always have SSE so it would be nice
to detect if the compiler somehow already has it on.
--
Sitsofe | http://sucs.org/~sits/
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