Advanced Micro Devices Corporation

Sun Microsystems, Inc.

Nexgen Microsystems

Nexgen, Inc.

Shrenik M Mehta

John Gregory Favor

Korbin S Van Dyke

Robert Alan Cargnoni

David R Stiles

Dale Robert Greenley

Harold L McFarland

William K Lam

Techniques are disclosed for automatically determining whether a potential constraint set to be applied to a portion of a circuit are overconstrained. An environment circuit supplies inputs to the circuit portion. Embodiments of the invention recognize that if the environment circuit produces a set of outputs that contain a pattern that is not present in the potential constraint set, then the potential constraint set is overconstrained. A verification tool establishes the properties for the environmental circuit based on the potential constraint set. If the verification tool determines that the outputs produced by the environment circuit conflict with the properties of the environment circuit, then the verification tool concludes that the potential constraint set is overconstrained, because the environment circuit produces a pattern that is not present in the potential constraint set. Advantageously, the laborious and error-prone process of manually determining the proper inputs to apply during formal verification is avoided.

Eliminate false passing of circuit verification through automatic detecting of over-constraining in formal verification

An integrated circuit having a normal mode for operating under normal operating conditions and a debug mode for operating to test and debug the integrated circuit. The integrated circuit includes a plurality of output pins that carry a first plurality of signals in the normal mode and carry a second plurality of signals in the debug mode. In one embodiment, the integrated circuit embodies a microprocessor. The microprocessor may include logic circuitry for enabling the second plurality of signals to be output from a multiplexer to the output pins in response to a predetermined event, such as a hit in an associated memory unit.

Method and apparatus for debugging an integrated circuit

A pipeline control system for implementing a virtual architecture having a complex instruction set is distributed over RISC-like semi-autonomous functional units in a processor. Decoder logic fetches instructions of the target architecture and translates them into simpler RISC-like operations. These operations, each having an associated tag, are issued to the functional units. Address processing unit computes addresses of the instructions and operands, performs segment relocation, and manages the processor's memory. Operations are executed by the units in a manner that is generally independent of operation processing by the other units. The units report termination information back to the decoder logic, but do not irrevocably change the state of the machine. Based on the termination information, the decoder logic retires normally terminated operations in order. Thus, the functional units enable multiple operations to be executed in a speculative and out-of-order manner to fully utilize the resources of the processor.

Method and apparatus for executing string instructions

A pipeline control system is distributed over the functional units (15, 17, 20, 25) in a processor (10). Decoder logic (12) issues operations, each with an associated tag, to the functional units, with up to n operations allowed to be outstanding. The units execute the operations and report termination information back to the decoder logic, but do not irrevocably change the state of the machine. Based on the termination information, the decoder logic retires normally terminated operations in order. If an operation terminates abnormally, the decoder logic instructs the units to back out of those operations that include and are later than the operation that terminated abnormally.

Computer processor with distributed pipeline control that allows

Semi-autonomous RISC pipelines for overlapped execution of RISC-like

A pipeline control system for implementing a virtual architecture having complex instruction set is distributed over RISC-like semi-autonomous functional units in a processor. Decoder logic fetches instructions of the target architecture and translates them into simpler RISC-like operations. These operations, each having an associated tag, are issued to the functional units. Address processing unit computes addresses of the instructions and operands, performs segment relocation, and manages the processor's memory. Operations are executed by the units in a manner that is generally independent of operation processing by the other units. The units report termination information back to the decoder logic, but do not irrevocably change the state of the machine. Based on the termination information, the decoder logic retires normally terminated operations in order. Thus, the functional units enable multiple operations to be executed in a speculative and out-of-order manner to fully utilize the resources of the processor.

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San Jose, CA, United States of America

Shrenik M Mehta