llvm-project

be4f7432 - [SelectionDAG] Deal with POISON for INSERT_VECTOR_ELT/INSERT_SUBVECTOR (part 3)

[SelectionDAG] Deal with POISON for INSERT_VECTOR_ELT/INSERT_SUBVECTOR (part 3) Target specific patches to avoid regressions seen after "part 1" aiming at fixing github issue #141034. One perhaps controversial change here is that convertToScalableVector now uses POISON instead of UNDEF for any additional elements added when converting to the scalable vector. This can avoid that we end up with things like t31: nxv1f32 = t32: v2f32 = extract_subvector t31, Constant:i64<0> t38: nxv1f32 = insert_subvector undef:nxv1f32, t32, Constant:i64<0> since if we instead try to insert into poison we can just use t31 instead of t38 without the risk that t31 would be more poisonous.