International Business Machines Corporation
Pairing issue queues for complex instructions and instruction fusion

Abstract:

Support for instruction fusion is provided. An indication whether an instruction is a paired instruction is received from an instruction decoder. Based on the indication, one dispatch slot or a paired dispatch slot is allocated in the instruction dispatcher queue. A mapper converts logical addresses of sources and targets of the instruction to physical addresses. Either one issue slot or a paired issue slot is allocated in an issue queue based on the indication from the instruction decoder. The instruction execution environment is loaded into the issue queue and issued to an execution unit.