[Mesa-dev] IROUND() issue
sroland at vmware.com
Fri May 18 18:16:39 PDT 2012
Am 19.05.2012 02:43, schrieb Kurt Roeckx:
> On Sat, May 19, 2012 at 02:19:36AM +0200, Roland Scheidegger wrote:
>> Am 18.05.2012 23:55, schrieb Kurt Roeckx:
>>> On Fri, May 18, 2012 at 09:11:38AM -0700, Jose Fonseca wrote:
>>>> It sounds a sensible plan, but I wonder if the multiple iround
>>>> versions are really worth it: SSE2 is guaranteed in x64, so we
>>>> could just start requiring SSE2 on x86, and only use the C for
>>>> other platforms.
>>> Is the "start requiring SSE2 on x86" a typo for x64?
>>> I still use x86 hardware that doesn't support sse2.
>> Would your hardware also not support sse?
> The one I'm using now does support sse but no sse2.
> What do you think about using cpuid for this?
Runtime cpu detection isn't really suitable for simple helpers like
IROUND which are used in a lot of places and supposed to map to very few
if not a single instruction, you'd have to use that somewhere in the
calling functions adding a lot of complexity. Noone's going to do that
Though at least linux distributions still compile without -msse as they
generally right now seem to require i686 (with cmov) but not sse. So
removing legacy x87 assembly might be premature.
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