Abstract: A processor comprises a cache, a first TLB, and a tag circuit. The cache comprises a data memory storing a plurality of cache lines and a tag memory storing a plurality of tags. Each of the tags corresponds to a respective one of the cache lines. The first TLB stores a plurality of page portions of virtual addresses identifying a plurality of virtual pages for which physical address translations are stored in the first TLB. The tag circuit is configured to identify one or more of the plurality of cache lines that are stored in the cache and are within the plurality of virtual pages. In response to a hit by a first virtual address in the first TLB and a hit by the first virtual address in the tag circuit, the tag circuit is configured to prevent a read of the tag memory in the cache.

Abstract: A method and apparatus for reducing instruction ITLB accesses. In one embodiment, the method may comprise generating a next virtual fetch address corresponding to an instruction fetch request and determining whether a current physical address translation is valid for the next virtual fetch address in response to its generation, wherein the determination may comprise detecting a change in the virtual page number of the next virtual fetch address relative to a virtual page number of a current virtual fetch address. The method may further comprise activating an ITLB circuit in response to determining that the current physical address translation is not valid for the next virtual fetch address, and performing the instruction fetch using the current physical address translation without activating the ITLB circuit in response to determining that the current physical address translation is valid for said next virtual fetch address.

Abstract: A decode unit is coupled to receive instruction bytes and to dispatch instructions to an execution subsystem. The decode unit comprises circuitry divided into a pipeline including a plurality of pipeline stages, wherein the circuitry is configured to concurrently initiate decode of a plurality of instructions and to dispatch at least an initial instruction of the plurality of instructions from a first pipeline stage of the plurality of pipeline stages. Furthermore, the circuitry is configured to dispatch at least one remaining instruction of the plurality of instructions from a second pipeline stage of the plurality of pipeline stages. The second pipeline stage is subsequent to the first pipeline stage in the pipeline.

Abstract: The present invention is an improved method and apparatus for selecting and replacing a block of a set of cache memory. The present invention provides for the weighted random replacement of blocks of cache memory by assigning indices to the memory blocks of a given set of cache memory. One of the assigned indices is then randomly selected by the present invention. The memory block of the given set to which the randomly selected index is assigned is replaced. The indices are assigned such that one or more blocks of the given set of cache memory have a high probability of replacement, whereas the other blocks of the given set of cache memory have significantly lower probabilities of replacement.