公开(公告)号：US20210055962A1

公开(公告)日：2021-02-25

申请号：US16546752

申请日：2019-08-21

Applicant: Arm Limited

Inventor： Michael David ACHENBACH ,  Robert Greg MCDONALD ,  Nicholas Andrew PFISTER ,  Kelvin Domnic GOVEAS ,  Michael FILIPPO ,  . ABHISHEK RAJA ,  Zachary Allen KINGSBURY

IPC: G06F9/48 ,  G06F9/38 ,  G06F9/50 ,  G06F9/52 ,  G06F9/30

Abstract: An apparatus and method are provided for operating an issue queue. The issue queue has a first section and a second section, where each of those sections comprises a number of entries, and where each entry is employed to store operation information identifying an operation to be performed by a processing unit. Allocation circuitry determines, for each item of received operation information, whether to allocate that operation information to an entry in the first section or to an entry in the second section. The operation information identifies not only the associated operation, but also each source operand required by the associated operation and availability of each source operand. Selection circuitry selects from the issue queue, during a given selection iteration, an operation to be issued to the processing unit, and selects that operation from amongst the operations whose required source operands are available. Availability update circuitry is used to update source operand availability for each entry whose operation information identifies as a source operand a destination operand of the selected operation in the given selection iteration. Further, a deferral mechanism is used to inhibit from selection by the selection circuitry, during at least a next selection iteration following the given selection iteration, any operation associated with an entry in the second section whose required source operands are now available due to that operation having as a source operand the destination operand of the selected operation in the given selection iteration. Such an approach can enable the effective capacity of the issue queue to be increased without adversely impacting the timing of the scheduling functionality performed in respect of the issue queue.