Code Sharing By Functions Having Different Addressing Requirements
Original Publication Date: 1982-Mar-01
Included in the Prior Art Database: 2005-Feb-09
In a computer system such as the IBM System/38, microprogramming is used to execute another level of instructions which include a highly used instruction. The microcode for executing the highly used instruction is optimized for performance reasons and does not permit a check point restart for lookaside buffer misses which can occur in a virtual storage system. The microcode for executing the highly used instruction includes microcode which can be shared for execution of other instructions that must be check point restarted on lookaside buffer misses. This imposes a problem of handling the lookaside buffer misses without impacting the performance of the highly used instruction. Check point return control information is passed as a return address in a dedicated LSR (local storage register) LBMC (lookaside buffer miss control).