A microprocessor includes a cache memory and a grabline instruction. The grabline instruction specifies a memory address that implicates a cache line of the memory. The grabline instruction instructs the microprocessor to initiate a zero-beat read-invalidate transaction on the bus to obtain ownership of the cache line. The microprocessor foregoes initiating the transaction on the bus when executing the grabline instruction if the microprocessor determines that a store to the cache line would cause an exception.