[llvm] 18eae33 - [SCEV] Fix usage of invalid IP with FoldingSet

[Ehud Katz via llvm-commits]

rGfcc2238b8bfb
<https://github.com/llvm/llvm-project/commit/fcc2238b8bfb9498b46a48d219193de8c00a25a0>
broke
the sanitizer "annotate" tests -
http://lab.llvm.org:8011/builders/sanitizer-x86_64-linux/builds/26137/,
which inherently, I think, seems like a good enough test case.
rG18eae3312297
<https://github.com/llvm/llvm-project/commit/18eae3312297cb197a3131f3ad9ca2bebb217415>
fixes
it.

On Fri, Mar 13, 2020 at 6:48 PM Roman Lebedev <lebedev.ri at gmail.com> wrote:

> This actually reaffirms my point - was there test covering this?
> If not, it might be good to add one.
>
> On Fri, Mar 13, 2020 at 7:45 PM Ehud Katz <ehudkatz at gmail.com> wrote:
> >
> > This is actually to fix a regression caused by
> rGfcc2238b8bfb9498b46a48d219193de8c00a25a0.
> > These lines of code actually existed before the change, but removed
> incorrectly.
> >
> > On Fri, Mar 13, 2020 at 6:38 PM Roman Lebedev <lebedev.ri at gmail.com>
> wrote:
> >>
> >> Any chance for a test for this?
> >>
> >> On Fri, Mar 13, 2020 at 7:37 PM Ehud Katz via llvm-commits
> >> <llvm-commits at lists.llvm.org> wrote:
> >> >
> >> >
> >> > Author: Ehud Katz
> >> > Date: 2020-03-13T18:36:58+02:00
> >> > New Revision: 18eae3312297cb197a3131f3ad9ca2bebb217415
> >> >
> >> > URL:
> https://github.com/llvm/llvm-project/commit/18eae3312297cb197a3131f3ad9ca2bebb217415
> >> > DIFF:
> https://github.com/llvm/llvm-project/commit/18eae3312297cb197a3131f3ad9ca2bebb217415.diff
> >> >
> >> > LOG: [SCEV] Fix usage of invalid IP with FoldingSet
> >> >
> >> > Fix the use of invalid Insertion Point pointer with the UniqueSCEVs
> FoldingSet,
> >> > which caused memory corruption.
> >> >
> >> > Added:
> >> >
> >> >
> >> > Modified:
> >> >     llvm/lib/Analysis/ScalarEvolution.cpp
> >> >
> >> > Removed:
> >> >
> >> >
> >> >
> >> >
> ################################################################################
> >> > diff  --git a/llvm/lib/Analysis/ScalarEvolution.cpp
> b/llvm/lib/Analysis/ScalarEvolution.cpp
> >> > index debd03bf47b8..030de8cf90b7 100644
> >> > --- a/llvm/lib/Analysis/ScalarEvolution.cpp
> >> > +++ b/llvm/lib/Analysis/ScalarEvolution.cpp
> >> > @@ -3339,6 +3339,10 @@ const SCEV *ScalarEvolution::getUDivExpr(const
> SCEV *LHS,
> >> >      }
> >> >    }
> >> >
> >> > +  // The Insertion Point (IP) might be invalid by now (due to
> UniqueSCEVs
> >> > +  // changes). Make sure we get a new one.
> >> > +  IP = nullptr;
> >> > +  if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP))
> return S;
> >> >    SCEV *S = new (SCEVAllocator)
> SCEVUDivExpr(ID.Intern(SCEVAllocator),
> >> >                                               LHS, RHS);
> >> >    UniqueSCEVs.InsertNode(S, IP);
> >> >
> >> >
> >> >
> >> > _______________________________________________
> >> > llvm-commits mailing list
> >> > llvm-commits at lists.llvm.org
> >> > https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-commits
>
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