Intel Corporation

Martin Licht

Jonathan D Combs

Andrew Huang

Mathew Lowes

Vikash Agarwal

Khary Alexander

Santhosh Srinath

Thomas Madaelil

Sundararajan Ramakrishnan

An embodiment of an integrated circuit may comprise a core and an instruction decoder communicatively coupled to the core to decode one or more instructions for execution by the core, where the instruction decoder includes two or more decode clusters in a parallel arrangement, and circuitry to offline a decode cluster of the two or more decode clusters. Other embodiments are disclosed and claimed.

Instruction decode cluster offlining

Systems, methods, and apparatuses for power efficient generation of length markers for a variable length instruction set are described. In one embodiment, a hardware processor core includes a decoder circuit to decode instructions into decoded instructions, an execution circuit to execute the decoded instructions, an instruction cache, an instruction length decoder circuit, a predecode cache comprising a predecode bit, for each section of multiple sections of instruction data, that indicates when that section is identified as an end boundary of a variable length instruction, an incomplete decode table comprising a bit, for each proper subset of sections of instruction data, that indicates when that proper subset of sections has one or more invalid predecode bits in the predecode cache; and a fetch circuit to, for an incoming address of instruction data, perform a lookup in the instruction cache and the incomplete decode table, and, when there is a hit in the instruction cache for the instruction data at the incoming address and a hit in the incomplete decode table that indicates a proper subset of sections of the instruction data for the incoming address has one or more invalid predecode bits in the predecode cache, causes the instruction length decoder circuit to generate one or more predecode bits for the proper subset of sections of the instruction data for the incoming address that has the one or more invalid predecode bits.

Circuitry and methods for power efficient generation of length markers for a variable length instruction set

An embodiment of an integrated circuit may comprise a return stack buffer (RSB), a speculative return stack buffer (SRSB), and circuitry coupled to the RSB and the SRSB, the circuitry to track a count until the SRSB is empty at a time of a prediction by a branch prediction unit, and return an output from the branch prediction unit that corresponds to one of the RSB and the SRSB based at least in part on the count until the SRSB is empty. Other embodiments are disclosed and claimed.

Count to empty for microarchitectural return predictor security

Systems, methods, and apparatuses relating to circuitry to implement toggle point insertion for a clustered decode pipeline are described. In one example, a hardware processor core includes a first decode cluster comprising a plurality of decoder circuits, a second decode cluster comprising a plurality of decoder circuits, and a toggle point control circuit to toggle between sending instructions requested for decoding between the first decode cluster and the second decode cluster, wherein the toggle point control circuit is to: determine a location in an instruction stream as a candidate toggle point to switch the sending of the instructions requested for decoding between the first decode cluster and the second decode cluster, track a number of times a characteristic of multiple previous decodes of the instruction stream is present for the location, and cause insertion of a toggle point at the location, based on the number of times, to switch the sending of the instructions requested for decoding between the first decode cluster and the second decode cluster.

Scalable toggle point control circuitry for a clustered decode pipeline

Techniques and mechanisms for providing branch prediction information to facilitate instruction decoding by a processor. In an embodiment, entries of a branch prediction table (BTB) each identify, for a corresponding instruction, whether a prediction based on the instruction (if any) is eligible to be communicated, with another prediction, in a single fetch cycle. A branch prediction unit of the processor determines a linear address of a fetch region which is under consideration, and performs a search of the BTB based on the linear address. A result of the search is evaluated to detect for any hit entry which indicates a double prediction eligibility. In another embodiment, where it is determined that double prediction eligibility is indicated for an earliest one the instructions represented by the hit entries, multiple predictions are communicated in a single fetch cycle.

Device, method and system for provisioning a real branch instruction and a fake branch instruction to respective decoders

A method and apparatus for disabling ways of a cache memory in response to history based usage patterns is herein described. Way predicting logic is to keep track of cache accesses to the ways and determine if an access to some ways are to be disabled to save power, based upon way power signals having a logical state representing a predicted miss to the way. One or more counters associated with the ways count accesses, wherein a power signal is set to the logical state representing a predicted miss when one of said one or more counters reaches a saturation value. Control logic adjusts said one or more counters associated with the ways according to the accesses.

Method and apparatus for saving power by efficiently disabling ways for a set-associative cache

A method and apparatus for disabling ways of a cache memory in response to history based usage patterns is herein described. Way predicting logic is to track consecutive misses to ways of a cache, i.e. hits/reads to other ways of cache. Based on the usage of ways and the non-usage of other ways, the way predicting logic determines if a way is to be powered down. In response to determining a way is to be powered down, the way predicting logic generates a power signal to power down an associated. Furthermore, upon a subsequent hit to a powered down way, the way predicting logic toggles the power signal to power up the associated way to ensure performance.

Growing community of inventors

Round Rock, TX, United States of America

Martin Licht