Micro-ops Register Packing for Renamer Port Optimization
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Solution Overview
Problem
Register renaming in microprocessors is a bottleneck for timing and performance, especially when the number of source and destination registers increases, limiting the number of micro-ops that can be renamed per cycle without increasing the number of rename ports.
Innovation Solution
Packing source and destination registers into a packed register structure before renaming, allowing for efficient register renaming operations by optimizing the number of registers sent to the renamer, which includes selecting valid registers based on age and attribute information, and controlling the packing to adhere to the preset number of rename ports.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the number of source and destination registers is increased to handle more micro-ops, then the processing capacity is improved, but the register renaming becomes a bottleneck for timing and performance
Solution Approach 1:
The patent applies preliminary action by packing source and destination registers into a packed register structure before the register renaming stage. This pre-packaging organization allows the renamer to process registers in batches more efficiently, reducing the renaming time bottleneck while maintaining high processing capacity.
Solution Approach 2:
The patent segments the register renaming process by introducing a packed register structure that groups multiple registers into a compact format. This segmentation allows the renamer to handle multiple registers through fewer rename ports in parallel, improving productivity without increasing the time required for each renaming operation.
2Productivity
If the number of rename ports is increased to rename more registers per cycle, then the productivity is improved, but the device complexity increases
Solution Approach 1:
The patent merges multiple register fields into a single packed register structure that can be processed by a limited number of rename ports. By combining source and destination registers into this compact structure, the system achieves high productivity with fewer rename ports, avoiding the complexity increase that would result from adding more ports.
Solution Approach 2:
The packed register structure serves multiple functions: it organizes source and destination registers, enables efficient batching for the renamer, and maintains compatibility with a fixed number of rename ports. This multi-functionality allows the system to achieve high register renaming throughput without proportionally increasing device complexity.
3Productivity
If more registers are packed into the packed register structure, then the number of micro-ops renamed per cycle is improved, but the packing and selection process becomes more complex
Solution Approach 1:
The patent changes the structural parameters of the register representation by introducing a packed register structure with specific field layouts for source and destination registers. This parameter change enables more efficient packing and selection algorithms, improving productivity while keeping the complexity of the packing process manageable through standardized field definitions.
Data Source
AI summary
A method and apparatus for register packing prior to register renaming in a microprocessor are provided. The method includes: receiving a plurality of micro operations (micro-ops) decoded from one or more instructions; packing a plurality of registers which are included in the micro-ops into a packed register structure including a plurality of packed registers based on a preset number of rename ports of a renamer through which the packed registers are read or written for register renaming; and sending the packed registers for register renaming.