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:
Sep. 05, 2000
Filed:
Apr. 30, 1998
James S Mattson, Jr, Campbell, CA (US);
Lacky V Shah, Fremont, CA (US);
William B Buzbee, Half Moon Bay, CA (US);
Hewlett-Packard Company, Palo Alto, CA (US);
Abstract
A method and apparatus varies branch prediction strategy associated with branch instructions in a trace of program code. The present invention first profiles branch instructions within a trace to record branching behavior. Next, the present invention partitions branch instructions into groups of branch instructions that can be statically predicted and groups of branch instructions that can be dynamically predicted. Branch instructions that are profiled to have 'strong' branching behavior (e.g., the same branch direction is taken 80% of the time) are placed in the group of branch instruction that are statically predicted. Branch instructions that are profiled to have 'weak' branching behavior (e.g., the same branch direction is taken 60% of the time) are placed in the group of branch instruction that are dynamically predicted. Finally, branch instructions are adjusted by associating an indication of prediction strategy with each profiled branch instruction. In an embodiment of the present invention, dynamic and static code caches are defined in physical memory by allocating pools of memory pages that have prediction flags set to dynamic and static, respectively. In this embodiment, the trace is translated into the dynamic and static caches by moving branch instruction and basic blocks of code associated with branch instructions into the appropriate code cache based on the groups into which the branch instructions were partitioned. The present invention may be used when a program is originally compiled or when a program is recompiled after a profile-based optimization run. Additionally, the present invention may be used as part of a run-time optimization strategy.