On Fri, 2013-05-17 at 01:11 -0400, David Edelsohn wrote: > On Thu, May 16, 2013 at 10:40 PM, Bill Schmidt > <wschm...@linux.vnet.ibm.com> wrote: > > This removes two degradations in CPU2006 for 32-bit PowerPC due to lost > > vectorization opportunities. Previously, GCC treated malloc'd arrays as > > only guaranteeing 4-byte alignment, even though the glibc implementation > > guarantees 8-byte alignment. This raises the guarantee to 8 bytes, > > which is sufficient to permit the missed vectorization opportunities. > > > > The guarantee for 64-bit PowerPC should be raised to 16-byte alignment, > > but doing so currently exposes a latent bug that degrades a 64-bit > > benchmark. I have therefore not included that change at this time, but > > added a FIXME recording the information. > > > > Bootstrapped and tested on powerpc64-unknown-linux-gnu with no new > > regressions. Verified that SPEC CPU2006 degradations are fixed with no > > new degradations. Ok for trunk? Also, do you want any backports? > > Okay. If you think that this is appropriate for 4.8 branch, that is > okay as well.
Yes, the degradation appears to have started last summer, so updating 4.8 would be good. > > Is there a FSF GCC Bugzilla open for the 437.leslie3d problem? The > FIXME doesn't need to contain the complete explanation, but it would > be nice to reference a longer explanation and not pretend to be > Fermat's theorem that is too large to write in the marge. There is now. I opened 57309 after submitting the patch, so I can reference that. Thanks, Bill > > Thanks, David >
