> -----Original Message----- > From: Eelco Chaudron <[email protected]> > Sent: Wednesday, July 14, 2021 10:12 AM > To: Amber, Kumar <[email protected]>; Aaron Conole > <[email protected]> > Cc: [email protected]; [email protected]; [email protected]; Van > Haaren, > Harry <[email protected]>; Ferriter, Cian <[email protected]>; > Stokes, Ian <[email protected]> > Subject: Re: [v11 10/11] dpif-netdev/mfex: Add AVX512 based optimized miniflow > extract
<snip> > > + /* Permute the packet layout into miniflow blocks shape. > > + * As different AVX512 ISA levels have different implementations, > > + * this specializes on the "use_vbmi" attribute passed in. > > + */ > > + __m512i v512_zeros = _mm512_setzero_si512(); > > + __m512i v_blk0 = v512_zeros; > > Although I did ACK this patchset, running make clang-analyzer, gave me the > following warning, which should be fixed: > > lib/dpif-netdev-extract-avx512.c:476:17: warning: Value stored to 'v_blk0' > during its > initialization is never read > __m512i v_blk0 = v512_zeros; > ^~~~~~ ~~~~~~~~~~ > 1 warning generated. Ah interesting, indeed its never read. Its also a "zeroed" register, so it has no runtime performance impact. (Magic of OoO execution, combined with register renaming :) The fix is simply to remove the " = v512_zeros;" part, resulting in this decl of the variable from __m512i v_blk0 = v512_zeros; to __m512i v_blk0; Will be included in v11. > Aaron, would it be possible to add a clang-analyzer run to the zero robot to > catch > newly introduced warnings? That'd be cool. I presume that a "scan-build" prefix to the build command is all that's needed, as usually the case with clang analyzer. Reproduced the above error using scan-build, so that seems to work :) Regards, -Harry <snip remaining patch> _______________________________________________ dev mailing list [email protected] https://mail.openvswitch.org/mailman/listinfo/ovs-dev
