Unified Physical Register File for Processor Efficiency
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Solution Overview
Problem
Modern processor architectures that separate speculative and non-speculative register states into distinct files (WRF and ARF) are inefficient in terms of power consumption and die-area usage due to unnecessary data copying and unused entries, leading to wasted resources.
Innovation Solution
A processor design that combines speculative and architectural register states into a single Physical Register File (PRF), utilizing a register alias table and preemptive spill operations to manage register allocation and deallocation efficiently, reducing the need for data copying and optimizing resource usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate WRF and ARF are used to store speculative and non-speculative register states, then register state management is enabled, but power consumption increases due to data copying
Solution Approach 1:
The patent merges the Working Register File (WRF) and Architectural Register File (ARF) into a single unified Physical Register File (PRF). This consolidation eliminates the need for data copying between separate files, thereby reducing power consumption while maintaining the ability to manage both speculative and non-speculative register states through a single structure with unified read/write ports.
2Reliability
If separate WRF and ARF are used to store speculative and non-speculative register states, then register state management is enabled, but die-area increases due to unused entries
Solution Approach 1:
By consolidating WRF and ARF into a single PRF, the patent eliminates redundant unused entries that would exist in separate files. The unified structure allows dynamic allocation of physical register entries based on actual usage needs, reducing the total die-area required while maintaining full register state management capability.
Solution Approach 2:
The patent implements dynamic register allocation within the unified PRF, where physical register entries are allocated and deallocated based on runtime needs rather than being statically assigned. This dynamic approach allows the register file to adapt to varying workload requirements, maximizing the utilization of each entry and reducing the total number of entries needed.
3Reliability
If WRF and ARF contain many entries with multiple read and write ports, then speculative and non-speculative register states can be maintained, but power consumption and area increase
Solution Approach 1:
The patent consolidates multiple register files into a single unified PRF that handles both speculative and non-speculative operations. By unifying the structure, the patent reduces the total number of read/write ports needed while maintaining the ability to support multiple concurrent operations, thereby reducing power consumption associated with port activity.
4Reliability
If WRF and ARF contain many entries with multiple read and write ports, then speculative and non-speculative register states can be maintained, but die-area increases
Solution Approach 1:
By merging WRF and ARF into a single unified PRF, the patent significantly reduces the die-area required for register storage. The unified structure eliminates redundant infrastructure and allows more efficient packing of register entries, reducing the overall area while maintaining the capability to maintain both speculative and non-speculative register states.
Data Source
AI summary
A processor includes an execution pipeline configured to execute instructions for threads, wherein the architectural state of a thread includes a set of register windows for the thread. The processor also includes a physical register file (PRF) containing both speculative and architectural versions of registers for each thread. When an instruction that writes to a destination register enters a rename stage, the rename stage allocates an entry for the destination register in the PRF. When an instruction that has written to a speculative version of a destination register enters a commit stage, the commit stage converts the speculative version into an architectural version. It also deallocates an entry for a previous version of the destination register from the PRF. When a register-window-restore instruction that deallocates a register window enters the commit stage, the commit stage deallocates local and output registers for the deallocated register window from the PRF.