[llvm-commits] [llvm] r162098 - in /llvm/trunk: lib/Analysis/MemoryBuiltins.cpp test/Transforms/InstCombine/objsize.ll

[Eli Friedman]

On Fri, Aug 17, 2012 at 7:16 AM, Benjamin Kramer
<benny.kra at googlemail.com> wrote:
> Author: d0k
> Date: Fri Aug 17 09:16:37 2012
> New Revision: 162098
>
> URL: http://llvm.org/viewvc/llvm-project?rev=162098&view=rev
> Log:
> Guard MemoryBuiltins against self-looping GEPs, which can occur in unreachable code due to constant propagation.
>
> Fixes PR13621.
>
> Modified:
>     llvm/trunk/lib/Analysis/MemoryBuiltins.cpp
>     llvm/trunk/test/Transforms/InstCombine/objsize.ll
>
> Modified: llvm/trunk/lib/Analysis/MemoryBuiltins.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/MemoryBuiltins.cpp?rev=162098&r1=162097&r2=162098&view=diff
> ==============================================================================
> --- llvm/trunk/lib/Analysis/MemoryBuiltins.cpp (original)
> +++ llvm/trunk/lib/Analysis/MemoryBuiltins.cpp Fri Aug 17 09:16:37 2012
> @@ -473,6 +473,10 @@
>  }
>
>  SizeOffsetType ObjectSizeOffsetVisitor::visitGEPOperator(GEPOperator &GEP) {
> +  // Ignore self-referencing GEPs, they can occur in unreachable code.
> +  if (&GEP == GEP.getPointerOperand())
> +    return unknown();

What happens when you have two GEPs referencing each other?

-Eli