Hi Loic,
FWIW something with the build or feature detection seems to be off, as I
just got an Illegal Instruction signal on the current master:
http://tracker.ceph.com/issues/7826
sage
On Sun, 23 Mar 2014, 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
>
>
