Apple Inc.

Suparn Vats

John H Mylius

Gerard Richard Williams

Ajay Bhatia

Vivekanandan Venugopal

Suresh Balasubramanian

Raghava Rao V Denduluri

Gopinath Venkatesh

Teng Wang

Stephan G Meier

James B Keller

Rohit Kumar

Conrado Blasco-Allue

Harsha Krishnamurthy

Karthik Rajagopal

Gaurav Shrivastav

Sambasivan Narayan

Abhijit Radhakrishnan

Sangeetha Mani

Daniel J Flees

Gerard R Williams Iii

An apparatus includes a control circuit configured to selectively activate, based on an operating mode signal, either a local clock signal or a pulse signal. The apparatus further includes a data storage circuit that is coupled to a data signal, the local clock signal, and the pulse signal. The data storage circuit may be configured to sample the data signal using the local clock signal during a first operating mode, and to sample the data signal using the pulse signal during a second operating mode.

Hybrid pulse/two-stage data latch

Hybrid pulse/master-slave data latch

A device is disclosed that includes a circuit block coupled to a local power node, and a power gating circuit coupled between the local power node and a global power supply. In one embodiment, the power gating circuit includes a first plurality of first switching devices with a first threshold voltage, and a second plurality of second switching devices with a second threshold voltage that is different from the first voltage threshold. The power gating circuit may isolate the local power node from the global power supply based on an isolation signal.

Method for power gating for wide dynamic voltage range operation

A method and apparatus for forcing equivalent outputs at start-up for replicated sequential circuits is disclosed. An integrated circuit (IC) includes first and second clocked logic circuits each coupled to receive a clock signal common to both, and each configured to produce equivalent logical outputs based on a common set of logic inputs. The IC further includes an equivalence circuit coupled to the outputs of each of the first and second clocked logic circuits. During a system start-up (e.g., power on) and before the clock signal has been applied, the equivalence circuit may detect if the outputs of the to first and second clocked logic circuits originally come up in different states. Responsive to determining that the outputs of the first and second clocked logic circuits are different, the equivalence circuit may cause the outputs to be forced to the same logical state.

Apparatus and method to force equivalent outputs at start-up for replicated sequential circuits

A method for designing clock gates which may reduce timing requirements associated with clock gating control signals may include identifying a clock gating function included in a Hardware Description Language of an integrated circuit, wherein the clock gating function may include capturing a state of an enable signal dependent upon a clock signal. The method may include determining a delay time for capturing the state of the enable signal dependent on a time difference between transitions of the enable signal and the clock signal. The method may include creating a gating circuit, in which the gating circuit includes a delay unit coupled to a source of the clock signal, and wherein a delay value is dependent upon the amount of time to delay capturing the enable signal. The method may include modifying the HDL model dependent upon the clock gating circuit.

Method for gating clock signals using late arriving enable signals

Methods and processors for managing load-store dependencies in an out-of-order instruction pipeline. A load store dependency predictor includes a table for storing entries for load-store pairs that have been found to be dependent and execute out of order. Each entry in the table includes hashed values to identify load and store operations. When a load or store operation is detected, the PC and an architectural register number are used to create a hashed value that can be used to uniquely identify the operation. Then, the load store dependency predictor table is searched for any matching entries with the same hashed value.

Load-store dependency predictor PC hashing

A system and method for reducing the latency of data move operations. A register rename unit within a processor determines whether a decoded move instruction is eligible for a zero cycle move operation. If so, control logic assigns a physical register identifier associated with a source operand of the move instruction to the destination operand of the move instruction. Additionally, the register rename unit marks the given move instruction to prevent it from proceeding in the processor pipeline. Further maintenance of the particular physical register identifier may be done by the register rename unit during commit of the given move instruction.

Zero cycle move

A free list in processor includes multiple banks for indicating availability of register identifiers used for register renaming. A register rename unit receives one or more destination architectural registers to rename with physical register identifiers. Responsive to determining the multiple banks within the free list are unbalanced with available physical register identifiers, one or more returning physical register identifiers are assigned to the destination architectural registers before assigning any physical register identifiers from any bank of the multiple banks with a lowest number of available physical register identifiers. A returning physical register identifier is a physical register identifier that is available again for assignment to a destination architectural register but not yet indicated in the free list as available. Each of the banks includes a single bit width decoded vector for indicating availability of given physical register identifiers.

System and method for register renaming with register assignment based on an imbalance in free list banks

Methods and apparatuses for managing load-store dependencies in an out-of-order processor. A load store dependency predictor may include a table for storing entries for load-store pairs that have been found to be dependent and execute out of order. Each entry in the table includes a counter to indicate a strength of the dependency prediction. If the counter is above a threshold, a dependency is enforced for the load-store pair. If the counter is below the threshold, the dependency is not enforced for the load-store pair. When a store is dispatched, the table is searched, and any matching entries in the table are armed. If a load is dispatched, matches on an armed entry, and the counter is above the threshold, then the load will wait to issue until the corresponding store issues.

Load-store dependency predictor content management

Techniques are disclosed for partitioning a placement of a circuit design into a plurality of regions. A constraint is generated based on the partitioning of the placement and on the sequential elements that are located within each region. The constraint is provided to one or more design tools, and the constraint forces sequential elements to fall within the same region on the next placement. Some regions can be classified as guides, and these regions act as a recommendation for a design tool instead of as an explicit rule. Other regions can be classified as inclusive, and sequential elements can be allowed to enter the region but any sequential elements already in the region must stay in the region. Further regions can be classified as exclusive, and no sequential elements may enter or leave these regions on the next placement of the circuit design.

Micro-regions for auto place and route optimization

Systems and methods for wire routing using virtual landing pads (VLPs) are described. In an embodiment, a method includes routing a wiring path between an output of a first circuit component and a VLP that represents an input of a second circuit component. For example, the VLP may have an area larger than the area of a physical pin of the second circuit component. The method may also include identifying a connection point on the VLP that is separated from an actual terminal of the second circuit, and completing the path between the connection point and the actual terminal. In some embodiments, the output of the first circuit component may also be represented by its own VLP. As such, systems and methods described herein may allow a circuit designer to perform routing procedures in a complex, highly integrated circuit, while reducing the circuit's overall capacitance and associated power consumption.

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Fremont, CA, United States of America

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