International Business Machines Corporation
Program counter (PC)-relative load and store addressing for fused instructions

Abstract:

Load store addressing can include a processor, which fuses two consecutive instruction determined to be prefix instructions and treats the two instructions as a single fused instruction. The prefix instruction of the fused instruction is auto-finished at dispatch time in an issue unit of the processor. A suffix instruction of the fused instruction and its fields and the prefix instruction's fields are issued from an issue queue of the issue unit, wherein an opcode of the suffix instruction is issued to a load store unit of the processor, and fields of the fused instruction are issued to the execution unit of the processor. The execution unit forms operands of the suffix instruction, at least one operand formed based on a current instruction address of the single fused instruction. The load store unit executes the suffix instruction using the operands formed by the execution unit.