[InstCombine] remove fold of an icmp pattern that should never happen

While removing a scalar shackle from an icmp fold, I noticed that I couldn't find any tests to trigger
this code path.

The 'and' shrinking transform should be handled by InstCombiner::foldCastedBitwiseLogic()
or eliminated with InstSimplify. The icmp narrowing is part of InstCombiner::foldICmpWithCastAndCast().

Differential Revision: https://reviews.llvm.org/D24031 


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@280370 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed