Abstract: A method and processor for performing on-demand scratch register reallocation by dynamically adjusting the number of scratch registers from within the pool of rename registers includes initially allocating from a set of physical registers one or more architected registers and a pool of one or more rename registers and allocating from the pool of rename registers an initial number of scratch registers for storing microcode operands. In response to detecting that a fetched instruction requires an additional scratch register beyond the initial number, a selected physical register is reallocated from among the pool of rename registers as the additional scratch register, and a flag is set to indicate the rename register is allocated as the additional scratch register. In response to determining that the additional scratch register is no longer needed, the additional scratch register is deallocated and the flag is reset, such that the selected physical register returns to the pool of rename registers.

Abstract: A method and processor for performing on-demand scratch register reallocation by dynamically adjusting the number of scratch registers from within the pool of rename registers includes initially allocating from a set of physical registers one or more architected registers and a pool of one or more rename registers and allocating from the pool of rename registers an initial number of scratch registers for storing microcode operands. In response to detecting that a fetched instruction requires an additional scratch register beyond the initial number, a selected physical register is reallocated from among the pool of rename registers as the additional scratch register, and a flag is set to indicate the rename register is allocated as the additional scratch register. In response to determining that the additional scratch register is no longer needed, the additional scratch register is deallocated and the flag is reset, such that the selected physical register returns to the pool of rename registers.

Abstract: A method of handling instructions in a load/store unit of a processor by dispatching instructions to the load/store unit, filling all physical entries of a reorder queue with tags corresponding to the instructions, and further dispatching one or more additional instructions to the load/store unit while all of the physical entries in the reorder queue are still full, i.e., still contain tags for uncompleted instructions. The invention may be implemented in either a load reorder queue or a store reorder queue. Multiple logical instruction tags are assigned in a count greater than the number of physical entries in the reorder queue. Of the multiple logical instruction tags assigned to a single one of the physical entries in the reorder queue, only the tag for the oldest instruction is allowed to execute. At least one virtual bit (VT) is provided to tag allocations for the load/store unit. This VT bit is flipped when a corresponding tag allocation wraps.