公开(公告)号：US20190012267A1

公开(公告)日：2019-01-10

申请号：US16018438

申请日：2018-06-26

Applicant: ARM Limited

Inventor： Luca SCALABRINO ,  Frederic Jean Denis ARSANTO ,  Claire AUPETIT

IPC: G06F12/0862 ,  G06F9/38 ,  G06F9/30

Abstract: An apparatus and method are provided for controlling use of a register cache. The apparatus has execution circuitry for executing instructions to process data values, and a register file comprising a plurality of registers in which to store the data values for access by the execution circuitry. A register cache is also provided that has a plurality of entries and is arranged to cache a subset of the data values for access by the execution circuitry. Each entry is arranged to cache a data value and an indication of the register associated with that cached data value. Prefetch circuitry then performs prefetch operations to prefetch data values from the register file into the register cache. Timing indication storage is used to store, for each data value to be generated as a result of instructions being executed within the execution circuitry, a register identifier for that data value, and timing information indicating when that data value will be generated by the execution circuitry. Cache usage control circuitry is then responsive to receipt of a plurality of register identifiers associated with source data values for a pending instruction yet to be executed by the execution circuitry, to generate, with reference to the timing information in the timing indication storage, a timing control signal to control timing of at least one prefetch operation performed by the prefetch circuitry. Such an approach can lead to significant improvements in the efficiency of utilisation of the register cache.

公开(公告)号：US20190012177A1

公开(公告)日：2019-01-10

申请号：US16018492

申请日：2018-06-26

Applicant: ARM Limited

Inventor： Luca SCALABRINO ,  Frederic Jean Denis ARSANTO ,  Claire AUPETIT

IPC: G06F9/38 ,  G06F9/30

Abstract: An apparatus and method are provided for controlling use of a register cache. The apparatus has decode circuitry for decoding instructions retrieved from memory, execution circuitry to execute the decoded instructions in order to perform operations on data values, and a register file having a plurality of registers for storing the data values to be operated on by the execution circuitry. Further, a register cache is provided that comprises a plurality of entries, and is arranged to cache a subset of the data values. Each entry is arranged to cache a data value and an indication of the register associated with that cached data value. Prefetch circuitry is then used to prefetch data values from the register file into the register cache. Further, operand analysis circuitry derives source operand information for an instruction fetched from memory, at least prior to the decode circuitry completing decoding of that instruction. It then causes provision to the prefetch circuitry of at least one register identifier determined from the source operand information. The prefetch circuitry then utilises that at least one register identifier when determining which data values to prefetch into the register cache. Such an approach can significantly increase the hit rate within the register cache, hence improving performance.