Date: Sat, 14 Jul 2012 01:57:11 +0200 From: magnum <john.magnum@...hmail.com> To: john-dev@...ts.openwall.com Subject: Re: Rotate and bitselect investigation On 2012-07-10 04:35, Solar Designer wrote: > On Tue, Jul 10, 2012 at 07:19:38AM +0530, Sayantan Datta wrote: >> On Tue, Jul 10, 2012 at 7:00 AM, Solar Designer <solar@...nwall.com> wrote: >>> This won't detect CPUs, though - where we also don't want to use >>> bitselect() most of the time (the instruction is only available with XOP >>> and is probably not used by current OpenCL SDKs since I think only >>> Intel's does vectorization) - but this code is mostly just for AMD and >>> NVIDIA GPUs now. We have faster MSCash2 code on CPU anyway. > >> So we should use manual bitselect by default. > > But we don't have a trick similar to cl_nv_pragma_unroll that would let > us detect AMD GPUs. So I am fine with us using bitselect() by default > and only disabling it on NVIDIA, unless/until we learn of a trick to > detect AMD GPU in OpenCL (or introduce such way by passing the info from > our C code). There is some stuff in common-opencl.c that can be used. We add -DDEVICE_IS_CPU when building for CPU. And we have -DDEVICE_INFO that can be parsed for vendor ID. I think Claudio can shed some light on the latter, I'm not sure how to use it. magnum
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