On 11/20/14 09:40, Jakub Jelinek wrote:
On Thu, Nov 20, 2014 at 07:36:03PM +0300, Ilya Enkovich wrote:
Hi,
MPX runtime checks some feature bits in order to check MPX is fully
supported. Runtime does it by cpuid calls but there is a
__builtin_cpu_supports which may be used for that. Unfortunately
currently it doesn't support required bits. Will it be OK to add them for
trunk?
I think using cpuid for that is just fine. __builtin_cpu_supports
is for ISA additions users might actually want to version code for,
MPX stuff, as the instructions are nops without hw support, are not
something one would multi-version a function for.
If anything, AVX512F and AVX512BW+VL might be good candidates for that, not
MPX.
SOrry, I didn't know the __builtin_cpu_supports was really only ment for
user multi-versioning. In that case, it won't make any sense to put the
MPX stuff in there.
Sorry for sending you down a wrong path Ilya.
jeff
