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Method and System for obtaining Force Prediction State by using Pattern History Tables (PHT)

IP.com Disclosure Number: IPCOM000241311D
Publication Date: 2015-Apr-15
Document File: 1 page(s) / 41K

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The IP.com Prior Art Database


A method and system is disclosed for obtaining force prediction state by using Pattern History Tables (PHT).

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Method and System for obtaining Force Prediction State by using Pattern History Tables (PHT)

In branch prediction logic, a pattern history table (PHT) predicts direction of branches based on alternating patterns such as Taken (T) and Not Taken (NT). The branches can be difficult to predict and sometimes, due to update in rules and timing, it result in 0% accuracy. There is a need for method and system that forcefully predicts direction of branches with utmost accuracy.

Disclosed is a method and system for obtaining force prediction state by using PHT. The method and system utilizes completion time trackers for monitoring the branches in a table that use PHT with 50/50 patterns at an accuracy of less than 50%. The detected branches thus change the prediction to a force state so as to obtain T patterns in all situations. Thereafter, the branches are kept in hold in the time trackers until an accuracy of 50% with the force prediction is obtained, or until the time trackers are timed out. In either case, the time tracker is given up and is used to monitor another PHT pattern.

This method and system works that at prediction time the force state is forced to be predicted taken. This will result in 50% accuracy.

The bad pattern is T, NT, T, NT ... This method and system detects this pattern and knows this branch behaves like this. So when this brnach is predicted, the table's prediction is overridden. The prediction for this branch can be held to Taken, and that