The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Feb. 24, 1998
Filed:
May. 14, 1996
Anne M Holler, San Jose, CA (US);
Lacky V Shah, Fremont, CA (US);
Hewlett-Packard Company, Palo Alto, CA (US);
Abstract
An untagged branch prediction cache is exploited by relocating branches during a final pass in the compilation process, after all other optimizations have been applied, where a pass is made over the instructions in each subprogram, and all branches that use the branch prediction cache (BPC) are placed into buckets, where each bucket corresponds to a position in the BPC. Recorded with each branch is its expected direction (taken, not taken), based either on profiling data or on static heuristics. Each bucket is then inspected. For buckets containing branches whose predicted directions conflict, an attempt is made to move some of those branches to another bucket. If other branches' positions are affected, the bucket inspection process is restarted, after recalculation of the bucket positions of all BPC branches. Branches that have matching predicted directions, but that currently fall into separate buckets, may be moved into the same bucket, so that the histories of branches can reinforce one another. Heuristics may be used to dictate which branches are considered, what code transformations are used to relocate branches, and whether both conflict avoidance and match enhancement are performed.