Setting values of portions of registers based on bit values

A processor employs a set of bits to indicate values of portions of registers of a register file. In response to a specified instruction indicating an expected change of instruction types to be executed, the processor sets one or more of the bits and, for subsequent instructions, interprets corresponding portions of the registers as having a specified value (e.g., zero). By employing the set of bits to set the values of the register portions, rather than setting the individual portions of the registers to the specified value, the processor conserves processor resources (e.g., power) when the processor transitions between executing instructions of different types.