Abstract: A quick predictor override system and method for a microprocessor that enables a correction to a quick predictor, branch prediction by a branch target address cache (BTAC), and rapid update to the quick predictor. For example, the microprocessor includes a quick predictor that provides branch prediction based on a local pattern history, and a large predictor in the form of the BTAC, which provides for branch prediction using a global pattern history. Branch prediction by the BTAC is the prevailing prediction if different, for a fetched cache address, than the branch prediction by the smaller, quick predictor. Accordingly, the target and direction for conditional branches provided by the BTAC for fetching the next cache instruction are used in favor of the target and direction previously provided by the quick predictor, and the quick predictor is quickly updated with the target and direction from the BTAC during a BTAC stage.

Abstract: In one embodiment, a prefetching method implemented in a microprocessor, the prefetching method comprising: issuing all prefetches remaining for a memory block as L3 prefetches based on a set of conditions; and issuing L2 prefetches for cache lines corresponding to the L3 prefetches upon reaching the end of the memory block.

Abstract: In one embodiment, a microprocessor, comprising: plural cores, each of the cores comprising a level 1 (L1) cache and a level 2 (L2) cache; and a shared level 3 (L3) cache comprising plural L3 tag array entries, wherein a first portion of the plural L3 tag array entries is associated with data and a second portion of the plural L3 tag array entries is decoupled from data, wherein each L3 tag array entry comprises tag information and data zero information, the data zero information indicating whether any data associated with the tag information is known to be zero or not.

Abstract: In one embodiment, a method implemented in a microprocessor, including receiving a fetched branch instruction; performing a privilege level test on a fetched branch instruction using a privilege level indicated by a first tag corresponding to a privilege level in a branch prediction table comprising plural entries, each of the plural entries comprising a tag corresponding to a privilege level; and providing a prediction branch miss for the fetched branch instruction based on a failure of the privilege level test.

Abstract: In one embodiment, a branch prediction control system is configured to move a mispredicted conditional branch from a smaller cache side that uses the lower complexity conditional branch predictor to one of the two large cache sides that uses the higher complexity conditional branch predictors. The move (write) is achieved according to a configurable probability or chance to escape misprediction recurrence and results in a reduced amount of mispredictions for the given branch instruction.

Abstract: In one embodiment, a microprocessor, comprising: first logic configured to dynamically adjust a maximum prefetch count based on a total count of predicted taken branches over a predetermined quantity of cache lines; and second logic configured to prefetch instructions based on the adjusted maximum prefetch count.

Abstract: In one embodiment, a microprocessor, comprising: a branch prediction table comprising plural entries, wherein at least a portion of the plural entries corresponds to an indirect branch type; and an indirect valid table; wherein based on an indirect branch instruction fetch, an entry corresponding to an indirect branch instruction in the branch prediction table is configured as invalid based on clearing a corresponding entry in the indirect valid table.

Abstract: In one embodiment, a droop reference, comprising: a programmable low pass filter configured to filter a supply voltage; and a digital-to-analog converter configured to provide a scaled version of the filtered supply voltage.

Abstract: In one embodiment, a microprocessor, comprising: a first data cache; and a second data cache configured to process both a miss in the first data cache resulting from a first load or store operation and an eviction from the first data cache to accommodate the first load or store operation, the second data cache configured to indicate to the first data cache that the eviction is complete before the eviction is actually complete based on a first state corresponding to the eviction.

Abstract: In one embodiment, a branch processing method comprising receiving information from at least two branch execution units; writing two updates per clock cycle to respective first and second write queues based on the information; and writing from the first write queue up to two updates per clock cycle into plural tables of a first predictor and a single update for the single clock cycle when there is an expected write collision, the first predictor comprising a single write or read/write port.

Abstract: In one embodiment, a branch processing method, comprising: assigning plural branch instructions for a given clock cycle to primary branch information and secondary branch information; routing the primary branch information along a first path having adder logic and the secondary branch information along a second path having no adder logic; and writing the primary branch information including a displacement branch target address to a branch order table (BOT) and the secondary branch information without a target address to the BOT.

Abstract: In one embodiment, a microprocessor, comprising: an instruction cache configured to receive an instruction fetch comprising a first byte portion and a second byte portion; a side cache tag array configured to signal further processing of the second byte portion in addition to the first byte portion based on a hit of the side cache tag array; and a side cache data array configured to store instruction data for the second byte portion.

Abstract: In one embodiment, a spread spectrum clock generator, comprising a digital delta sigma modulator coupled to a fractional N, phase locked loop (PLL), the PLL comprising a discrete-time capacitance multiplier loop filter, the discrete-time capacitance multiplier loop filter comprising: an amplifier comprising a non-inverting input and an inverting input; a first switched capacitor resistor and a capacitor coupled to the non-inverting input, the capacitor coupled between the first switched capacitor resistor and the non-inverting input; and a second switched capacitor resistor coupled to the inverting input.

Abstract: In one embodiment, a microprocessor, comprising: a translation lookaside buffer (TLB) configured to indicate that a virtual page address corresponding to a physical page address of a page of memory that a memory access instruction is attempting to access is missing in the TLB; a first micro-op corresponding to a first memory access instruction and configured to initiate a first speculative tablewalk based on a miss in the TLB of a first virtual page address; and a second micro-op corresponding to a second memory access instruction, the second micro-op configured to take over an active first speculative tablewalk of the first micro-op at its current stage of processing based on being older than the first micro-op and further based on having a virtual page address and properties that match the first virtual page address and properties for the first memory access instruction.

Abstract: In one embodiment, a microprocessor, comprising: prediction logic comprising a branch predictor comprising a group of multi-set associative tables, each of the tables corresponding to branch pattern histories of different lengths; and control logic configured to provide an adjustable write policy for the prediction logic.

Abstract: In one embodiment, a droop detector circuit, comprising: a reference oscillator; plural delay lines configured to receive signals from the reference oscillator; and logic configured to detect droop in a voltage regulator based on an output of the voltage regulator and outputs of each of the plural delay lines.

Abstract: In one embodiment, a microprocessor, comprising: first logic configured to detect that a fetched cache address matches at least one of two previous cache addresses; and second logic configured to adjust a branch pattern used for conditional branch prediction based on the match and combine the cache address with the adjusted branch pattern to form a conditional branch predictor address.