On Thu, Oct 9, 2014 at 11:35 AM, Yangfei (Felix) <felix.y...@huawei.com> wrote: > >> > > > On Thu, Oct 09, 2014 at 09:04:49AM +0000, Yangfei (Felix) wrote: >> > > > > On Wed, Oct 08, 2014 at 11:00:24PM +0800, Felix Yang wrote: >> > > > > The enclosed patch for 4.8 & 4.9 branch is a backport of r211885 >> > > > > from >> > trunk. >> > > > > >> > > > > The only change is to use: >> > > > > >> > > > > for (def_rec = DF_INSN_INFO_DEFS (insn_info); *def_rec; >> > > > > def_rec++) >> > > > > >> > > > > other than the new FOR_EACH_INSN_INFO_DEF interface. >> > > > > >> > > > > Bootstrapped on x86_64-SUSE-Linux for both branches. OK to apply? >> > > > >> > > > ChangeLog entry is missing, plus description why do you want to >> > > > backport >> > it. >> > > > If it fixes a bug on the branches, it would be better to have a >> > > > bugzilla PR for that, and definitely a testcase. >> > > > >> > > >> > > Yeah, I will add a ChangeLog entry for this patch when it is committed. >> > > I encountered the same issue when working on my local customized >> > > 4.8/4.9 >> > branches. Not reproduceable with the official 4.8/4.9 branches. >> > > I thinks it's just an enhancement for the loop invariant pass to >> > > make it more >> > versatile. It's better that 4.8/4.9 branches also inlcude this enhancement. >> > > OK? >> > >> > If it is just an enhancement, then those generally are not backported >> > to release branches (exceptions possible of course, but there needs to be a >> strong reason). >> > Each pass has some risk of breaking something, exposing previously >> > only latent bugs in later passes etc. >> > >> > Jakub >> >> We can treat it as bugfix, as we got incorrect code when it triggers. >> It just happens so rarely. Does it worth backporting? > > And the patch fix this bug by making the loop invariant pass more > conservative. > I didn't find a PR or testcase on trunk for this patch either.
We at least want a testcase for the "we got incorrect code when it triggers". Richard. >
