Neuron Cache Hardware Branch Prediction for Pipelined Architectures

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Solution Overview

Problem

Current computing environments face inefficiencies in branch prediction, particularly in pipelined architectures, where incorrect branch predictions lead to discarded speculative instructions and pipeline restarts, highlighting the need for improved target address prediction techniques.

Innovation Solution

A branch prediction system incorporating a neuron cache with trained neural network weights and logic to predict target addresses for branch instructions, specifically utilizing a hardware-based indirect branch prediction facility that adapts to difficult-to-predict branches, leveraging deep neural network principles and selective training for improved performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If traditional branch prediction techniques are used, then the prediction process is simple, but branch prediction accuracy deteriorates for difficult-to-predict branches

Engineering Contradiction:
Improvebranch prediction accuracyVSAvoidprediction structure complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The branch prediction system is segmented into multiple specialized prediction structures, each optimized for different types of branches. The neuron cache handles difficult-to-predict indirect branches, while other structures handle regular branches, allowing each segment to specialize and achieve high accuracy without overwhelming complexity in a single structure.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

A branch resolution unit acts as an intermediary that selects which prediction structure to use based on the branch type. This mediator directs difficult-to-predict indirect branches to the neuron cache while routing other branches to appropriate prediction structures, resolving the contradiction by intelligently distributing work based on branch characteristics.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Productivity

If pipelined architecture is used to improve processing speed, then instruction execution efficiency improves, but pipeline restarts increase when branch predictions are incorrect

Engineering Contradiction:
Improveinstruction execution efficiencyVSAvoidpipeline restart time
Core Design Contradiction:
ProductivityVSLoss of time

Solution Approach 1:

The neuron cache performs preliminary learning and adaptation during idle pipeline periods and between branch executions. By pre-learning branch patterns and storing them in the neuron cache before they are needed for prediction, the system prepares prediction data in advance, enabling accurate predictions when branches are encountered and avoiding pipeline restarts.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system implements feedback mechanisms where prediction outcomes are monitored and used to update the neuron cache. When prediction accuracy is verified or when new branch patterns are detected, the neuron cache adapts by updating its weights and parameters, creating a continuous feedback loop that improves predictions over time and reduces pipeline restarts.

Inventive Principle:
Principle #23Feedback

Data Source

PatentUS11803386B2Neuron cache-based hardware branch prediction
Publication Date: 2023.10.31 INTERNATIONAL BUSINESS MACHINE CORPORATION
  • US11803386B2 patent drawing
  • US11803386B2 patent drawing
  • US11803386B2 patent drawing

AI summary

A branch prediction system includes a neuron cache and logic coupled to the neuron cache. The neuron cache includes one or more weights of a neural network model trained for one or more selected code sections, and the logic is to be used with the neuron cache to predict a target address for a branch instruction of the one or more selected code sections.