On Sat, May 14, 2016 at 02:36:39PM +0300, Arthur ??i??eic?? wrote: > În ziua de vineri, 13 mai 2016, la 23:47:07 EEST, Willy Tarreau a scris: > > On Fri, May 13, 2016 at 11:25:28PM +0200, Cyril Bonté wrote: > > > > In the mean time, there may be a -fsomething option to disable a > > > > bogus optimization which causes this, but that's not easy to spot > > > > as it will depend on any side effect of other code :-/ > > > > > > I was trying to identify one, and indeed, once I add "-fno-tree-sra", it > > > works as expected. > > > > This one already exists in gcc 4 and 5, so its implementation might be bogus > > in 6. The doc says : > > > > -ftree-sra > > Perform scalar replacement of aggregates. This pass replaces > > structure references with scalars to prevent committing > > structures to memory too early. This flag is enabled by default at -O and > > higher. > > > > Thus I suspect that by delaying memory references a bit too much they end > > up completely forgetting to commit the changes :-/ > > > > Thank you everyone for the effort to diagnose this. > > I've also managed to build 1.6.5 with "-fno-tree-sra" and I confirm that all > seems to be working as expected. > > I'll pass the info in this thread to the Arch Linux maintainers. > I don't think they'll go back to gcc 5 but so far the additional flag seems > like the better option.
What is the most important is to report this to the gcc maintainers so that they can fix the bug. The fix will naturally flow into the distros. Willy
