f58930f705
If there is a single store, then loads must either load the stored value or uninitialized memory (undef). If the stored value may be poison, then replacing an uninitialized memory load with it would be incorrect. Fall back to the generic code in that case. This PR only fixes the case where there is a literal poison store -- the case where the value is non-trivially poison will still get miscompiled by phi simplification later, see #96631. Fixes https://github.com/llvm/llvm-project/issues/97702.