Move the last{a,b} operation to the vector operand of the binary instruction if
the binop's operand is a splat value. This essentially converts the binop
to a scalar operation.
Example:
// If x and/or y is a splat value: lastX (binop (x, y)) --> binop(lastX(x), lastX(y))
clang-tidy: warning: 'auto OldBinOp' can be declared as 'auto *OldBinOp' [llvm-qualified-auto]
not useful