US 2011/0238962 A1Published application

Register Checkpointing for Speculative Modes of Execution in Out-of-Order Processors

AssigneeInternational Business Machines Corporation

InventorsHarold W. Cain, III, Kattamuri Ekanadham, IL Park

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Abstract

A mechanism is provided for generating a checkpoint for a speculatively executed portion of code. The mechanisms identify, during a speculative execution of a portion of code, a register renaming operation occurring to an entry in a register renaming table of the processor. In response to the register renaming operation occurring to the register renaming table, a determination is made as to whether an update to an entry in a hardware-implemented recovery renaming table is to be performed. If so, the entry in the hardware-implemented recovery renaming table is updated. The entry in the recovery renaming table is part of the checkpoint for the speculative execution of the portion of code.

Claims20

Dependent claims

A method, in a data processing system, for generating a checkpoint for a speculatively executed portion of code, comprising:

identifying, by a processor of the data processing system, during a speculative execution of a portion of code, a register renaming operation occurring to an entry in a register renaming table of the processor;
in response to the register renaming operation occurring to the register renaming table, determining, by the processor, if an update to an entry in a hardware-implemented recovery renaming table of the processor is to be performed;
and
updating, by the processor, the entry in the hardware-implemented recovery renaming table in response to a determination that the entry in the recovery renaming table is to be updated, wherein the entry in the recovery renaming table is part of the checkpoint for the speculative execution of the portion of code.

1 more element

An apparatus, comprising:

a register renaming table unit;
a recovery renaming table unit;
and
a logic unit coupled to both the register renaming table unit and the register recovery table unit, wherein the logic unit operates to:
identify, during a speculative execution of a portion of code, a register renaming operation occurring to an entry in the register renaming table;
in response to the register renaming operation occurring to the register renaming table, determine if an update to an entry in the recovery renaming table unit is to be performed;
and
update the entry in the recovery renaming table unit in response to a determination that the entry in the recovery renaming table unit is to be updated, wherein the entry in the recovery renaming table unit is part of a checkpoint for the speculative execution of the portion of code.

5 more elements

Dependencies are inferred from the claim text.