[llvm] [RISCV] Use ISD::XOR instead of RISCVISD::VMXOR_VL in lowerVectorMaskVecReduction of scalable ISD::VECREDUCE_AND (PR #121812)

[Philip Reames via llvm-commits]

https://github.com/preames edited https://github.com/llvm/llvm-project/pull/121812