Method and apparatus for saving the effective address of floating point

Abstract

A method is provided for recovering the effective address of memory instructions in an out-of-order microprocessor for use by an exception handler upon the occurrence of one of an exception and a systems management interrupt. The microprocessor comprises at least one execution unit for executing a plurality of instructions out-of-order and a re-order buffer having storage locations for buffering result data produced from the execution of the plurality of instructions. Each instruction is associated with a location designator to identify a unique storage location within the re-order buffer in which the result data for an executed instruction is written. The microprocessor further comprises a memory order buffer having storage locations for buffering memory instructions waiting for access to memory for execution, these storage locations also being identified by corresponding location designators. According to this embodiment of the microprocessor, the effective address of memory instructions can be reconstructed by utilizing the location designators of the ROB (Reorder Buffer) to find the corresponding storage location in the MOB (Memory Order Buffer) at which place the linear address for the instruction may be found. By associating both the retirement and exception information of the memory instructions stored within the storage locations of the re-order buffer with the corresponding memory instructions and information stored within the memory order buffer, the linear address of either the youngest, valid, retiring memory uop or the oldest, valid, excepted memory uop can be selected, written to memory and subsequently used to reconstruct the effective address of the memory instruction for use by an exception handler.