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Re: [PATCH] Fix PR91790
- From: Segher Boessenkool <segher at kernel dot crashing dot org>
- To: Richard Biener <rguenther at suse dot de>
- Cc: gcc-patches at gcc dot gnu dot org, Bill Schmidt <wschmidt at linux dot ibm dot com>
- Date: Thu, 19 Sep 2019 13:34:21 -0500
- Subject: Re: [PATCH] Fix PR91790
- References: <nycvar.YFH.7.76.1909170941380.5566@zhemvz.fhfr.qr>
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?
You can use -malign-natural to get stricter alignment requirements,
that might help.
Cc:ing Bill, this is vectorizer :-)
Segher