[llvm-commits] [llvm] r120974 - in /llvm/trunk: include/llvm/Analysis/AliasAnalysis.h lib/Transforms/Scalar/DeadStoreElimination.cpp test/Transforms/DeadStoreElimination/simple.ll

İsmail Dönmez ismail at namtrac.org
Mon Dec 6 00:27:10 PST 2010


Hi;

On Mon, Dec 6, 2010 at 10:24 AM, Benjamin Kramer
<benny.kra at googlemail.com>wrote:

>
> On 06.12.2010, at 02:48, Chris Lattner wrote:
>
> > Author: lattner
> > Date: Sun Dec  5 19:48:06 2010
> > New Revision: 120974
> >
> > URL: http://llvm.org/viewvc/llvm-project?rev=120974&view=rev
> > Log:
> > Fix PR8728, a miscompilation I recently introduced.  When optimizing
> > memcpy's like:
> >  memcpy(A, B)
> >  memcpy(A, C)
> >
> > we cannot delete the first memcpy as dead if A and C might be aliases.
> > If so, we actually get:
>
> Aren't the operands of memcpy guaranteed not to overlap, so this would be
> undefined behaviour?


Apparently Adobe didn't know about it:
https://bugzilla.redhat.com/show_bug.cgi?id=638477

Regards,
ismail
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