Loop Coalescing Method Reduces Branching Overhead
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Solution Overview
Problem
In processor development, nested loops in software pipeline technology hinder processing speed due to conditional statements and their branching, which increase processor overhead, especially with complex operations like modulo, necessitating an effective loop coalescing method to simplify conditional statement operations.
Innovation Solution
A loop coalescing method and device that remove the inner-most loop and generate a guard code using an if-conversion method, allowing the outer operation to proceed based on a guard calculated by a new instruction storing information related to the loop's iteration period in a register, thereby simplifying the operation and reducing branching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If nested loops are used in software pipeline technology, then loop operations can be performed, but processing speed is reduced due to conditional statements and branching
Solution Approach 1:
The patent extracts the inner-most loop from the nested loop structure and processes it separately. The outer loop operations are performed once per inner loop iteration, eliminating the need for complex nested conditional statements. This separation reduces the branching complexity while maintaining the loop operation functionality, directly addressing the contradiction between processing speed and conditional statement complexity.
Solution Approach 2:
The patent segments the nested loop into two independent parts: the outer loop operation and the inner loop operation. By dividing the original nested structure into separate processing stages, the patent eliminates the need for complex nested conditionals, reducing processor overhead and improving processing speed while preserving the essential loop functionality.
2Productivity
If conditional statements with complex operations like modulo are used, then loop control can be achieved, but processor overhead is increased
Solution Approach 1:
The patent replaces expensive modulo operations with simpler arithmetic operations. By using a counter variable that increments by one each iteration and comparing it against the loop bound, the patent eliminates complex modulo operations in favor of simple addition and comparison, significantly reducing processor overhead while maintaining loop control functionality.
Solution Approach 2:
The patent changes the parameter representation from using modulo operations on iteration counters to using simple incrementing counters with comparison against bounds. This parameter transformation replaces complex mathematical operations with basic arithmetic, reducing computational overhead while achieving the same loop control effect.
3Productivity
If nested loops are coalesced into inner-most loop, then software pipeline technology can be effectively utilized, but the number of branches in conditional statements increases
Solution Approach 1:
The patent extracts the inner-most loop iteration logic from the nested structure and applies it to the outer loop operations. By taking out the repetitive inner loop pattern and applying it once to outer operations, the patent achieves effective software pipeline utilization while minimizing the number of conditional branches, as the extracted logic eliminates redundant nesting conditions.
Data Source
AI summary
A loop coalescing method and a loop coalescing device are disclosed. The loop coalescing method comprises removing an inner-most loop from among nested loops, so that an outer operation provided outside of the inner-most loop is performed when a condition of a conditional statement is satisfied, generating a guard code by applying an if-conversion method to the conditional statement, and converting a guard by using an instruction calculating the guard of the guard code, the instruction calculating the guard using a register where information related to a period of time corresponding to the number of iterations of the inner-most loop is stored.