Processor Array Search Pipeline for Reduced Loop Overhead
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Solution Overview
Problem
Existing processor architectures incur significant loop and pipelining overhead during array searching due to repeated comparisons and branch decisions, particularly when searching large arrays with multiple misses.
Innovation Solution
A processor architecture with an instruction pipeline that includes a load stage, compare stage, store stage, and loop hit detect stage, allowing for concurrent execution of array element loading, comparison, and result storage, with a loop decision stage to aggregate and evaluate comparison results, reducing loop overhead by performing multiple comparisons per clock cycle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional sequential array searching is performed with repeated loop iterations, then the search can be completed, but loop overhead and pipelining overhead significantly increase processing time and resource consumption
Solution Approach 1:
The array search operation is segmented into distinct pipeline stages: load stage for fetching array elements, compare stage for comparing elements with target value, store stage for storing comparison results, and loop hit detect stage for detecting search completion. This segmentation allows parallel execution of multiple search operations simultaneously, eliminating sequential loop overhead.
Solution Approach 2:
The loop hit detect stage performs preliminary detection of search hits before the traditional branch decision is made. By detecting hits in advance during the pipeline execution, the system can avoid repeated loop iterations and branch overhead, completing the search operation more efficiently.
2Measurement precision
If multiple array elements are compared sequentially in traditional processor architecture, then the search is accurate, but the resource penalty from repeated loops increases overhead
Solution Approach 1:
Multiple comparison operations are merged into a single pipeline execution flow. The load stage loads multiple array elements, the compare stage compares them with the target value, and the store stage stores all comparison results simultaneously. This merging eliminates the need for separate loop control mechanisms while maintaining search accuracy.
Solution Approach 2:
The pipeline stages serve multiple functions: the compare stage not only compares array elements with the target value but also implicitly performs loop continuation decisions. The loop hit detect stage combines hit detection with pipeline control, reducing the need for separate branch control logic and simplifying the overall device complexity.
Data Source
AI summary
A processor with instruction storage configured to store processor instructions, data storage configured to store processor data representing an array, the array including plural data elements, a controller, and an instruction pipeline. The instruction pipeline includes: a load stage circuit configured to load an array element from the data storage, a compare stage circuit configured to compare the array element to a reference value, a store stage circuit configured to store a set of results that includes a result of the comparison of the array element to the reference value, and a loop hit detect stage circuit configured to determine whether any of the set of results is associated with a hit on the reference value.