On 25/03/2014 20:13, Kevin Greenan wrote: > +1 > > Yeah, that sounds better... Let's keep this as simple as possible. I'll rework the https://bitbucket.org/jimplank/gf-complete/pull-request/4/defer-the-decision-to-use-a-given-sse accordingly. Would it be sensible to compile with SSE optimizations only if all are available ( SSE2, SSSE3, SSE4, SSE4_PCMUL ) and not attempt to distinguish betweel SSSE3 being available but not SSE4_PCMUL etc. From what I understand at this point that kind of distinction is going to be difficult to manage anyway. Is it too simplistic ? > > -kevin > > > On Tue, Mar 25, 2014 at 12:08 PM, Loic Dachary <loic@xxxxxxxxxxx <mailto:loic@xxxxxxxxxxx>> wrote: > > Andreas Peters suggested another approach, which makes sense to me : have one plugin with SSE optimizations enabled, another without them and chose at runtime between the two. > > What do you think ? > > On 23/03/2014 20:50, Loic Dachary wrote: > > Hi Laurent, > > > > In the context of optimizing erasure code functions implemented by Kevin Greenan (cc'ed) and James Plank at https://bitbucket.org/jimplank/gf-complete/ we ran accross a question you may have the answer to: can gcc -msse2 (or -msse* for that matter ) have a negative impact on the portability of the compiled binary code ? > > > > In other words, if a code is compiled without -msse* and runs fine on all intel processors it targets, could it be that adding -msse* to the compilation of the same source code generate a binary that would fail on some processors ? This is assuming no sse specific functions were used in the source code. > > > > In gf-complete, all sse specific instructions are carefully protected to not be run on a CPU that does not support them. The runtime detection is done by checking CPU id bits ( see https://bitbucket.org/jimplank/gf-complete/pull-request/7/probe-intel-sse-features-at-runtime/diff#Lsrc/gf_intel.cT28 ) > > > > The corresponding thread is at: > > > > https://bitbucket.org/jimplank/gf-complete/pull-request/4/defer-the-decision-to-use-a-given-sse/diff#comment-1479296 > > > > Cheers > > > > -- > Loïc Dachary, Artisan Logiciel Libre > > -- Loïc Dachary, Artisan Logiciel Libre
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