Reproducer: ``` define i1 @src(i32 %In) { %c1 = icmp samesign sgt i32 %In, -1 %c2 = icmp samesign eq i32 %In, 1 %V = select i1 %c1, i1 %c2, i1 false ret i1 %V } define i1 @tgt(i32 %In) { %c2 = icmp samesign eq i32 %In, 1 ret i1 %c2 } ``` We should check this flag in `Operator::hasPoisonGeneratingFlags`.