Hewlett-Packard Development Company, L.p.

Susith Rohana Fernando

Russell C Brockmann

Kevin Safford

James Earl McCormick, Jr

James R Callister

Anuj Dua

Brian M Kelly

Systems, methodologies, media, and other embodiments associated with acquiring instruction addresses associated with performance monitoring events are described. One exemplary system embodiment includes logic for recording instruction and state data associated with events countable by performance monitoring logic associated with a pipelined processor. The exemplary system embodiment may also include logic for traversing the instruction and state data on a cycle count basis. The exemplary system may also include logic for traversing the instruction and state data on a retirement count basis.

Acquiring instruction addresses associated with performance monitoring events

A branch target structure predicts a branch target address for an instruction flow. To conserve space, only a portion of the branch target address is stored. The branch target address is reconstructed assuming that an unspecified portion of a current branch instruction address matches corresponding bits of the branch target address. A comparator determines if the unspecified portion of the current branch instruction address matches corresponding bits of the branch target address. If the unspecified portion of the current branch instruction address does not match the corresponding bits of the branch target address, update of the branch target structure is inhibited. Otherwise update allowed.

Method and apparatus for reducing branch prediction table pollution

A method and an apparatus for re-creating a trace of instructions from an emulated instruction set when running on hardware optimized for a different instruction set, such as IA-32 instructions running on an IA-64 machine, are disclosed. An execution trace buffer is created that maintains desired information about instructions as they are executed and retired. The invention may be configured such that certain desired information helpful to debugging the system may be written to the buffer as the instructions are retired. This information may include the addresses of sequential or branch instructions, or other relevant information that can be gathered continuously and non-intrusively as instructions are executed. The information may be read from the buffer and output in a machine-visible form at the user's convenience.

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Fort Collins, CO, United States of America

Susith Rohana Fernando