Translation Address Cache for Indirect Branch Handling
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Solution Overview
Problem
Existing approaches to translating architectural-level instructions between instruction set architectures face challenges with indirectly-branched processes, as it is difficult to determine the target of an indirect branch, leading to potential microprocessor stalls and inefficiencies.
Innovation Solution
The method involves hashing the address of an instruction to determine if an alternate version exists, and if so, aborting the retrieval of the original instruction to execute the alternate version, which provides optimized performance by avoiding decode operations and utilizing a translation address cache to store native translations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If chained software optimizations are used to pass control between optimizations, then execution efficiency is improved, but the system cannot handle indirectly-branched processes effectively
Solution Approach 1:
The patent pre-calculates and stores multiple possible target addresses in the translation address cache before indirect branching occurs. When an indirect branch is encountered, the system can immediately retrieve the correct target address from the pre-computed cache entries, avoiding stalls and maintaining both high execution efficiency and proper handling of indirect branches.
2Adaptability or versatility
If the target of an indirect branch is determined dynamically, then adaptability is improved, but processing time increases causing microprocessor stalls
Solution Approach 1:
The system pre-computes and stores multiple possible indirect branch target addresses in the translation address cache during instruction translation or cache fill operations. When an indirect branch is executed, the correct target is already available in the cache, eliminating dynamic computation delays and preventing microprocessor stalls while maintaining adaptability to different branch targets.
3Speed
If translation address cache is used to store native translations, then retrieval speed is improved, but memory usage increases
Solution Approach 1:
The patent extracts and stores only the essential translation address information needed for indirect branching in the translation address cache, rather than storing complete translation contexts. This selective extraction maintains fast retrieval speed while minimizing the memory footprint of the cache structure.
Data Source
AI summary
Embodiments related to fetching instructions and alternate versions achieving the same functionality as the instructions from an instruction cache included in a microprocessor are provided. In one example, a method is provided, comprising, at an example microprocessor, fetching an instruction from an instruction cache. The example method also includes hashing an address for the instruction to determine whether an alternate version of the instruction which achieves the same functionality as the instruction exists. The example method further includes, if hashing results in a determination that such an alternate version exists, aborting fetching of the instruction and retrieving and executing the alternate version.