Hardware-assisted program trace collection with selectable call-signature capture

Abstract

Hardware-assisted program tracing is facilitated by a processor that includes a root instruction address register, a program trace signature computation unit and a call signature register. When a program instruction having an address matching the root instruction address register is executed, a program trace signature is captured in the call signature register and capture of branch history is commenced. By accumulating different values of the call signature register, for example in response to an interrupt generated when the root instruction is executed, software that performs program tracing can obtain signatures of all of the multiple execution paths that lead to the root instruction, which is also specified by software in order to set different root instructions for program tracing. In an alternative implementation, a storage for multiple call signatures is provided in the processor and read at once by the software.

Description

[0001]This U.S. Patent Application is a Continuation-in-Part of, and thus claims priority under 35 U.S.C. 120 to, U.S. patent application Ser. No. 13 / 214,352 filed on Aug. 22, 2011, the disclosure of which is incorporated herein by reference. The above-incorporated U.S. Patent Application has at least one inventor in common with the present U.S. Patent Application and is assigned to the same Assignee.BACKGROUND OF THE INVENTION[0002]1. Field of the Invention[0003]The present invention is related to hardware-assisted program tracing, and more specifically to a processor and method that capture a call signature when a specified root instruction is executed, and optionally when the call signature also has a specified value.[0004]2. Description of Related Art[0005]Run-time program tracing software provides valuable insight as to the actual patterns of execution encountered during program execution. Such information can be used to selectively optimize program code and to inform developer...

AI Technical Summary

Benefits of technology

This patent text describes a processor, computer system, computer program product, and method that can uniquely identify program trace segments between call and return pairs during program execution. This is accomplished by computing the program call signature when a specified root instruction is executed. This technology can aid in program profiling and debugging. Additionally, the patent describes how the processor can have a single or multiple register to store the call signature, which can be determined based on the processor's operating mode. The technical effects of this technology include improved program profiling and debugging and improved efficiency in identifying program trace segments.

Problems solved by technology

However, specific hardware mechanisms to support program tracing along specific program paths are not generally present in today's processors.

Images