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:
Oct. 13, 1998
Filed:
May. 01, 1996
Kattamuri Ekanadham, Yorktown Heights, NY (US);
Rudolph Nathan Rechtschaffen, Scarsdale, NY (US);
International Business Machines Corporation, Armonk, NY (US);
Abstract
The history table of the present invention is utilized to record a context oriented predictor associated with one or more branch instructions. The context oriented predictor preferably is derived from the history table by incorporating within each entry of the history table a vector of branch predictors. This vector comprises for each value of n (where n can be arbitrarily set, yet preferably remains fixed within a given implementation), a set of 2 predictors. When the prefetching action of a processor causes the history table to be accessed, the vector of predictors for a given branch, called the ancestor branch, is retrieved from the history table and stored. After n such retrievals, the action history of the last n branches is used to access a predictor from the vector of predictors that was associated with the n-th ancestor (or predecessor) of the next upcoming branch. This predictor is used to predict the n-th successor branch of the ancestor branch. If necessary, the subsequent action of such n-th successor branch is used to update the predictor derived from the vector associated with the ancestor branch, and the vector is restored to the history table at the location indexed according to the ancestor branch instruction. The context oriented history table may be embodied in a BHT or DHT.