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Re: [PATCH] Fix PR82129
- From: Richard Biener <rguenther at suse dot de>
- To: Jakub Jelinek <jakub at redhat dot com>
- Cc: gcc-patches at gcc dot gnu dot org
- Date: Tue, 12 Sep 2017 16:46:15 +0200 (CEST)
- Subject: Re: [PATCH] Fix PR82129
- Authentication-results: sourceware.org; auth=none
- References: <alpine.LSU.2.20.1709121603340.26836@zhemvz.fhfr.qr> <20170912141628.GH1701@tucnak>
On Tue, 12 Sep 2017, Jakub Jelinek wrote:
> On Tue, Sep 12, 2017 at 04:09:41PM +0200, Richard Biener wrote:
> >
> > The following "fixes" PR82129 (hides the issue). It folds
> > writes from uninitialized data to CLOBBERs:
> >
> > - *h5_26(D) = tv_24(D);
> > + *h5_26(D) ={v} {CLOBBER};
> >
> > Bootstrap & regtest running on x86_64-unknown-linux-gnu.
>
> Won't that affect -W{,maybe-}unitialized a lot?
Not sure - as current it fails bootstrap because I need to guard
against not folding things like foo.bar = x_2(D) (we assert to
have clobbers only on full objects).
Richard.
> > 2017-09-12 Richard Biener <rguenther@suse.de>
> >
> > PR tree-optimization/82129
> > * gimple-fold.c (fold_gimple_assign): Fold stores from undefined
> > values to clobbers.
> >
> > * gcc.dg/torture/pr82129.c: New testcase.