The described embodiments include a processor that executes a vector instruction. The processor starts by receiving an input vector and optionally receiving a predicate vector as inputs. The processor then executes the vector instruction, which causes the processor to determine a key element position in the input vector and generate a result vector. When generating the result vector, if the predicate vector is received, for each element in the result vector for which a corresponding element of the predicate vector is active, otherwise, for each element of the result vector, the processor sets each element of the result vector to the right of the key element to a first predetermined value and sets each element of the result vector at or to the left of the key element to a second predetermined value. The processor then sets one or more processor status flags based on the values in the result vector.