38.1 Read-Modify-Write Operations

Any instruction that specifies a file register as part of the instruction performs a Read-Modify-Write (RMW) operation. The register is read, the data is modified, and the result is stored according to either the Working (W) register, or the originating file register, depending on the state of the destination designator ‘d’ (see Table 38-1 for more information). A read operation is performed on a register even if the instruction writes to that register.