REGISTER ALLOCATION SYSTEM USING RECURSIVE QUEUING DURING SOURCE CODE COMPILATION

A computing system operates upon register requests serially referenced in an instruction stream to assign quantities to registers selected from unlike subsets or classes of registers. During compilation, the register usage of quantities serially scanned in the instruction stream is determined. Upon determining during the serial scan the need for a new quantity in a register, the quantity is logged to a queue, or pending set, of load point quantities and assigned a complete set count indicative of the number of registers the quantity requires, plus the number of permanent registers, plus the number of restricted registers, plus the number of registers in register classes for which it is not a candidate. Upon determining during the serial scan the reuse of a quantity in a register (already assigned or pending assignment), the complete set counts of quantities in the pending set which are candidates for a same register class as the reuse quantity are incremented. When the complete set count for a quantity equals the total number of available registers, a complete set is detected and the quantity is assigned to the remaining register. The register assignment procedure is recursively executed to generate load instructions for addressability register manipulations conditionally for base address constants not already in a register.