Non-Contiguous Register File Specifier for Fixed-Width Instruction Encoding
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Solution Overview
Problem
Modern microprocessors face challenges in achieving high parallelism and tolerating increasing latency due to limited register resources, which are exacerbated by the fixed instruction width and legacy architectures that complicate the encoding of new instructions and register specifications.
Innovation Solution
The implementation of a non-contiguous register file specifier in a fixed-width instruction set architecture allows for extended register specifications, enabling the use of a larger register file without altering the instruction encoding, by translating non-contiguous register specifiers into contiguous logical specifiers and remapping them to physical registers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a fixed-width instruction set architecture is used, then code density and compatibility with existing architectures are improved, but the ability to encode extended register specifications is worsened
Solution Approach 1:
The register specifier is divided into multiple segments: a primary register field and additional specifier fields that can be concatenated to form extended register addresses. This segmentation allows the fixed-width instruction to encode larger register files by combining multiple smaller fields rather than requiring a single large contiguous field.
Solution Approach 2:
The instruction encoding nests multiple levels of specification: base register fields are nested within extended specifier fields, which are in turn nested within the complete instruction word. This nested structure enables compact representation of extended register addresses within the fixed instruction width constraint.
2Productivity
If the number of registers is increased to support higher parallelism, then processing efficiency is improved, but the register file size and access complexity increase
Solution Approach 1:
Instead of expanding the register file in a single dimensional array, the patent organizes registers into multiple banks or sets that can be independently accessed. The extended specifier fields enable selection across these dimensional divisions, effectively adding another dimension to the register organization that supports higher parallelism without proportionally increasing access complexity.
3Ease of operation
If legacy architecture compatibility is maintained, then ease of operation is improved, but the ability to implement new instruction formats is worsened
Solution Approach 1:
The fixed-width instruction format is designed with universal fields that can serve multiple purposes: primary register fields work for both legacy and extended modes, while additional specifier fields can be activated or deactivated based on the instruction type. This multi-functionality allows the same instruction format to maintain legacy compatibility while enabling extended register specifications for new instructions.
Data Source
AI summary
There are provided methods and computer program products for implementing instruction set architectures with non-contiguous register file specifiers. A method for processing instruction code includes processing a fixed-width instruction of a fixed-width instruction set using a non-contiguous register specifier of a non-contiguous register specification. The fixed-width instruction includes the non-contiguous register specifier.