公开(公告)号：US20230244495A1

公开(公告)日：2023-08-03

申请号：US17590722

申请日：2022-02-01

Applicant: Apple Inc.

Inventor： Ethan R. Schuchman ,  Niket K. Choudhary ,  Kulin N. Kothari ,  Haoyan Jia ,  Ian D. Kountanis ,  Douglas C. Holman ,  Wei-Han Lien ,  Pruthivi Vuyyuru

IPC: G06F9/38 ,  G06F9/30

CPC classification number: G06F9/3844 ,  G06F9/3861 ,  G06F9/30145 ,  G06F9/30058 ,  G06F9/30079

Abstract: A processor may include an instruction distribution circuit and a plurality of execution pipelines. The instruction distribution circuit may distribute a conditional instruction to a first execution pipeline for execution when the conditional instruction is associated with a prediction of a high confidence level, or to a second execution pipeline for execution when the conditional instruction is associated with a prediction of a low confidence level. The second execution pipeline, not the first execution pipeline, may directly instruct the processor to obtain an instruction from a target address for execution, when the conditional instruction is mispredicted. Thus, when the conditional instruction is distributed to the first execution pipeline for execution and determined to be mispredicted, the first execution pipeline may cause the conditional instruction to be re-executed in the second execution pipeline to cause the instruction from the correct target address to be obtained for execution.

公开(公告)号：US20210173654A1

公开(公告)日：2021-06-10

申请号：US16705023

申请日：2019-12-05

Applicant: Apple Inc.

Inventor： Deepankar Duggal ,  Kulin N. Kothari ,  Conrado Blasco ,  Muawya M. Al-Otoom

IPC: G06F9/38 ,  G06F9/30

Abstract: Systems, apparatuses, and methods for implementing zero cycle load bypass operations are described. A system includes a processor with at least a decode unit, control logic, mapper, and free list. When a load operation is detected, the control logic determines if the load operation qualifies to be converted to a zero cycle load bypass operation. Conditions for qualifying include the load operation being in the same decode group as an older store operation to the same address. Qualifying load operations are converted to zero cycle load bypass operations. A lookup of the free list is prevented for a zero cycle load bypass operation and a destination operand of the load is renamed with a same physical register identifier used for a source operand of the store. Also, the data of the store is bypassed to the load.

公开(公告)号：US10228951B1

公开(公告)日：2019-03-12

申请号：US14831661

申请日：2015-08-20

Applicant: Apple Inc.

Inventor： Kulin N. Kothari ,  Mridul Agarwal ,  Pradeep Kanapathipillai

IPC: G06F9/38 ,  G06F9/30

Abstract: Systems, apparatuses, and methods for committing store instructions out of order from a store queue are described. A processor may store a first store instruction and a second store instruction in the store queue, wherein the first store instruction is older than the second store instruction. In response to determining the second store instruction is ready to commit to the memory hierarchy, the processor may allow the second store instruction to commit before the first store instruction, in response to determining that all store instructions in the store queue older than the second store instruction are non-speculative. However, if it is determined that at least one store instruction in the store queue older than the second store instruction is speculative, the processor may prevent the second store instruction from committing to the memory hierarchy before the first store instruction.

公开(公告)号：US10983801B2

公开(公告)日：2021-04-20

申请号：US16562675

申请日：2019-09-06

Applicant: Apple Inc.

Inventor： Kulin N. Kothari ,  Mridul Agarwal

IPC: G06F9/38 ,  G06F9/30

Abstract: A processor includes a load/store unit that includes one or more load pipelines and one or more store pipelines. Load operations may be issued into the load pipelines out of order with respect to older store operations. If a load operation is executed out or order with an older store operation that writes one or more bytes read by the load operation, and if the store operation is issued shortly after the load operation, such that the load operation is still in the load pipeline when the store operation is issued, some cases of flushing may be converted to replays by detecting the ordering violation while the load operation is still in the load pipeline.

公开(公告)号：US10437595B1

公开(公告)日：2019-10-08

申请号：US15070435

申请日：2016-03-15

Applicant: Apple Inc.

Inventor： Pradeep Kanapathipillai ,  Stephan G. Meier ,  Gerard R. Williams, III ,  Mridul Agarwal ,  Kulin N. Kothari

IPC: G06F9/38 ,  G06F9/30

Abstract: Systems, apparatuses, and methods for optimizing a load-store dependency predictor (LSDP). When a younger load instruction is issued before an older store instruction and the younger load is dependent on the older store, the LSDP is trained on this ordering violation. A replay/flush indicator is stored in a corresponding entry in the LSDP to indicate whether the ordering violation resulted in a flush or replay. On subsequent executions, a dependency may be enforced for the load-store pair if a confidence counter is above a threshold, with the threshold varying based on the status of the replay/flush indicator. If a given load matches on multiple entries in the LSDP, and if at least one of the entries has a flush indicator, then the given load may be marked as a multimatch case and forced to wait to issue until all older stores have issued.

公开(公告)号：US11829763B2

公开(公告)日：2023-11-28

申请号：US16539684

申请日：2019-08-13

Applicant: Apple Inc.

Inventor： Yuan C. Chou ,  Viney Gautam ,  Wei-Han Lien ,  Kulin N. Kothari ,  Mridul Agarwal

IPC: G06F9/345 ,  G06F9/38 ,  G06F9/30 ,  G06F9/50 ,  G06F12/0802

CPC classification number: G06F9/3455 ,  G06F9/30043 ,  G06F9/3861 ,  G06F9/5005 ,  G06F12/0802

Abstract: A system and method for efficiently reducing the latency of load operations. In various embodiments, logic of a processor accesses a prediction table after fetching instructions. For a prediction table hit, the logic executes a load instruction with a retrieved predicted address from the prediction table. For a prediction table miss, when the logic determines the address of the load instruction and hits in a learning table, the logic updates a level of confidence indication to indicate a higher level of confidence when a stored address matches the determined address. When the logic determines the level of confidence indication stored in a given table entry of the learning table meets a threshold, the logic allocates, in the prediction table, information stored in the given entry. Therefore, the predicted address is available during the next lookup of the prediction table.

公开(公告)号：US11416254B2

公开(公告)日：2022-08-16

申请号：US16705023

申请日：2019-12-05

Applicant: Apple Inc.

Inventor： Deepankar Duggal ,  Kulin N. Kothari ,  Conrado Blasco ,  Muawya M. Al-Otoom

IPC: G06F9/30 ,  G06F9/38

Abstract: Systems, apparatuses, and methods for implementing zero cycle load bypass operations are described. A system includes a processor with at least a decode unit, control logic, mapper, and free list. When a load operation is detected, the control logic determines if the load operation qualifies to be converted to a zero cycle load bypass operation. Conditions for qualifying include the load operation being in the same decode group as an older store operation to the same address. Qualifying load operations are converted to zero cycle load bypass operations. A lookup of the free list is prevented for a zero cycle load bypass operation and a destination operand of the load is renamed with a same physical register identifier used for a source operand of the store. Also, the data of the store is bypassed to the load.

公开(公告)号：US11175917B1

公开(公告)日：2021-11-16

申请号：US17018875

申请日：2020-09-11

Applicant: Apple Inc.

Inventor： Mridul Agarwal ,  Kulin N. Kothari ,  Nikhil Gupta

IPC: G06F9/38 ,  G06F11/14 ,  G06F9/30 ,  G06F9/48

Abstract: In an embodiment, a processor comprises a reservation station that issues a first load operation for execution, a store queue, and a replayed load buffer coupled in parallel with the reservation station. During execution of the first load operation, the store queue detects that the first load operation hits on a first store operation in the store queue that lacks store data and causes a replay of the first load operation. The replayed load buffer captures an identifier of the first load operation and the first store operation based on the replay of the first load operation, wherein the replayed load buffer monitors the reservation station for issuance of a first store data operation corresponding to the first store operation and issues the first load operation for reexecution based on the issuance of the first store data operation.

公开(公告)号：US20210072997A1

公开(公告)日：2021-03-11

申请号：US16562675

申请日：2019-09-06

Applicant: Apple Inc.

Inventor： Kulin N. Kothari ,  Mridul Agarwal

IPC: G06F9/38 ,  G06F9/30

Abstract: A processor includes a load/store unit that includes one or more load pipelines and one or more store pipelines. Load operations may be issued into the load pipelines out of order with respect to older store operations. If a load operation is executed out or order with an older store operation that writes one or more bytes read by the load operation, and if the store operation is issued shortly after the load operation, such that the load operation is still in the load pipeline when the store operation is issued, some cases of flushing may be converted to replays by detecting the ordering violation while the load operation is still in the load pipeline.

公开(公告)号：US20210049015A1

公开(公告)日：2021-02-18

申请号：US16539684

申请日：2019-08-13

Applicant: Apple Inc.

Inventor： Yuan C. Chou ,  Viney Gautam ,  Wei-Han Lien ,  Kulin N. Kothari ,  Mridul Agarwal

IPC: G06F9/345 ,  G06F9/38 ,  G06F9/30 ,  G06F9/50 ,  G06F12/0802

Abstract: A system and method for efficiently reducing the latency of load operations. In various embodiments, logic of a processor accesses a prediction table after fetching instructions. For a prediction table hit, the logic executes a load instruction with a retrieved predicted address from the prediction table. For a prediction table miss, when the logic determines the address of the load instruction and hits in a learning table, the logic updates a level of confidence indication to indicate a higher level of confidence when a stored address matches the determined address. When the logic determines the level of confidence indication stored in a given table entry of the learning table meets a threshold, the logic allocates, in the prediction table, information stored in the given entry. Therefore, the predicted address is available during the next lookup of the prediction table.