[PATCH] D129765: [DAG] SimplifyDemandedBits - don't early-out for multiple use values

Wed Jul 27 04:54:14 PDT 2022

RKSimon added a comment.

In D129765#3681963 <https://reviews.llvm.org/D129765#3681963>, @uabelho wrote:

> Hi,
>
> I'm seeing a crash
>
>   13:07:13 llc: ../lib/CodeGen/SelectionDAG/TargetLowering.cpp:1878: bool llvm::TargetLowering::SimplifyDemandedBits(llvm::SDValue, const llvm::APInt &, const llvm::APInt &, llvm::KnownBits &, llvm::TargetLowering::TargetLoweringOpt &, unsigned int, bool) const: Assertion `!Known.hasConflict() && "Bits known to be one AND zero?"' failed.
>
> with this patch. I'll see if I can extract a reproducer.

Cheers, its almost certainly exposed an existing bug

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https://reviews.llvm.org/D129765