Apple Inc.

Christopher M Tsay

Richard F Russo

Mridul Agarwal

Gideon N Levinsky

Shih-Chieh Wen

Lior Zimet

James Nolan Hardage

Tal Kuzi

Charles E Tucker

Jeffrey E Gonion

Pradeep Kanapathipillai

James Vash

Deepankar Duggal

John H Kelm

Jeff Gonion

Conrado Blasco

John D Pape

Mahesh K Reddy

Daniel U Becker

Richard H Larson

Christopher S Thomas

Andrew H Lin

Corey C Stappenbeck

In an embodiment, a processor includes hardware circuitry which may be used to authenticate instruction operands. The processor may execute instructions that perform operand authentication both speculatively and non-speculatively. During speculative execution of such instructions, the processor may execute authentication such that no differences in observable state of the processor, relative to authentication result, are detectable via a side channel. During speculative execution, a result of authentication may be deferred until speculative execution of the instruction, and additional instructions, may be completed. Upon resolution of a condition that indicates acceptance of the speculative execution, a speculative execution result may cause a processor exception and stalling of execution at the instruction to be performed.

Consistent speculation of pointer authentication

Techniques are disclosed relating to data synchronization barrier operations. A system includes a first processor that may receive a data barrier operation request from a second processor include in the system. Based on receiving that data barrier operation request from the second processor, the first processor may ensure that outstanding load/store operations executed by the first processor that are directed to addresses outside of an exclusion region have been completed. The first processor may respond to the second processor that the data barrier operation request is complete at the first processor, even in the case that one or more load/store operations that are directed to addresses within the exclusion region are outstanding and not complete when the first processor responds that the data barrier operation request is complete.

DSB operation with excluded region

An interrupt delivery mechanism for a system includes and interrupt controller and a plurality of cluster interrupt controllers coupled to respective pluralities of processors in an embodiment. The interrupt controller may serially transmit an interrupt request to respective cluster interrupt controllers, which may acknowledge (Ack) or non-acknowledge (Nack) the interrupt based on attempting to deliver the interrupt to processors to which the cluster interrupt controller is coupled. In a soft iteration, the cluster interrupt controller may attempt to deliver the interrupt to processors that are powered on, without attempting to power on processors that are powered off. If the soft iteration does not result in an Ack response from one of the plurality of cluster interrupt controllers, a hard iteration may be performed in which the powered-off processors may be powered on.

Scalable interrupts

A system and method for efficiently handling instruction execution ordering. In various embodiments, a processor includes multiple execution lanes, each executing instructions of a particular type, which are not executed by one or more of the other execution lanes. The instruction queue includes one queue for each particular execution lane. Control logic identifies a current youngest age used in allocated entries of the multiple queues, and determines a starting age based on the identified current youngest age and the number of instructions to be issued. Beginning with the determined starting age, ages (in program order) are assigned to a group of instructions being allocated in the multiple queues. Ages of entries in the multiple queues are updated for instructions not being issued based on the number of instructions being issued. Instructions being issued have age differences between them below a threshold.

Age tracking for independent pipelines

Techniques are disclosed relating to speculative writes to special-purpose registers (SPRs). In some embodiments, the disclosed techniques may reduce or avoid system instruction stalls while waiting for SPR writes, which may improve processor performance. In some embodiments, a processor includes a first storage element configured to store a non-speculative value of a special-purpose register and speculative storage circuitry configured to store one or more speculative values of the special-purpose register based on one or more speculatively-performed writes to the special-purpose register. In some embodiments, the processor includes control circuitry configured to: propagate the non-speculative value of the special-purpose register to control other circuitry and provide a youngest speculative value of the special-purpose register in the speculative storage circuitry as a speculative read of the special-purpose register.

Speculative writes to special-purpose register

In some embodiments, a system includes a register file, a plurality of clock gating circuits, a free list circuit, and a register allocation adjustment circuit. The register file includes a plurality of registers. The clock gating circuits control receipt of a clock signal at respective regions of registers. The free list circuit performs multiple search operations in parallel to identify unallocated registers. The register allocation adjustment circuit implements a mapping between registers identified by the free list circuit and registers of the register file such that the multiple search operations identify whether registers of a first region are unallocated prior to identifying whether registers of a second region are unallocated. As a result, a region of the register file is less likely to be in use during a particular clock cycle and a clock gating circuit may prevent a clock signal from being received at the region.

Register allocation system

In an embodiment, an integrated circuit may include one or more processors. Each processor may include multiple processor cores, and each core has a different design/implementation and performance level. The processor may support multiple processor states (PStates). Each PState may specify an operating point (e.g. a combination of supply voltage magnitude and clock frequency), and each PState may be mapped to one of the processor cores. During operation, one of the cores is active: the core to which the current PState is mapped. If a new PState is selected and is mapped to a different core, the processor may automatically context switch the processor state to the newly-selected core and may begin execution on that core. The context switch may be performed using a special purpose register (SPR) interconnect. Each processor core in a given processor may be coupled to the SPR interconnect to permit access to the external SPRs.

Hardware migration between dissimilar cores

Growing community of inventors

Austin, TX, United States of America

Christopher M Tsay