On Thu, 19 Sep 2019, Bill Schmidt wrote: > > On 9/19/19 1:34 PM, Segher Boessenkool wrote: > > Hi! > > > > On Tue, Sep 17, 2019 at 09:45:54AM +0200, Richard Biener wrote: > >> The following fixes an old vectorizer issue with realignment support > >> (thus only powerpc is affected) and BB vectorization. The realignment > >> token is set up from the wrong data-ref which causes an SSA verification > >> failure but in other circumstances might simply generate wrong code. > >> > >> Bootstrap running on x86_64-unknown-linux-gnu, I'll install this > >> as obvious on trunk. > >> > >> PPC folks - you know best how to appropriately test a target > >> where we use the re-alignment optimization. IIRC on later > >> powerpc hardware this isn't exercised at all since we can use > >> unaligned accesses. > >> > >> The issue is at least present on the GCC 9 branch as well but I'd > >> appreciate testing where it exercises the path before considering > >> a backport. > > Is there a testcase? > > > Richard, can you turn the PR's reported test into a torture test case? We > post P7 big-endian results frequently to gcc-testresults, and this bug hasn't > fired on anything there, so it's not covered by existing tests. Nothing has > turned up on the testers since your patch went in, so having the new test > added should be sufficient, I'd think. P7 or older running big-endian is > what's needed to test realignment support.
I was hoping you guys could take a stab at that, eventually also creating a wrong-code runnable testcase (one that would alignment-fault at runtime for using the wrong alignment token). The testcase in the PR is unwieldly, aka C++, and it likely requires machine specific options to more reliably trigger - IIRC I needed -mcpu=e300c3 or so thus apply subtarget specific tuning. OTOH the patch was so obvious... Richard. > Thanks, > > Bill > > > > > You can use -malign-natural to get stricter alignment requirements, > > that might help. > > > > Cc:ing Bill, this is vectorizer :-) > > > > > > Segher > -- Richard Biener <rguent...@suse.de> SUSE Software Solutions Germany GmbH, Maxfeldstrasse 5, 90409 Nuernberg, Germany; GF: Felix Imendörffer; HRB 247165 (AG München)
