Intermediate Register Mapper for Out-of-Order Processor Pipeline Efficiency
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Solution Overview
Problem
Current high-performance out-of-order processors face resource constraints at the unified main mapper, leading to increased die area, complexity, power consumption, and access time, as they cannot free unified main mapper entries until instructions complete, limiting instruction reuse and pipeline efficiency.
Innovation Solution
The introduction of an intermediate register mapper allows for the early release of unified main mapper entries by moving logical-to-physical register renaming data to the intermediate mapper once an instruction has finished executing but not completed, enabling earlier reuse of mapper entries and optimizing resource allocation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If unified main mapper entries are held until instruction completion, then instruction execution correctness is ensured, but mapper entry reuse is limited and pipeline efficiency decreases
Solution Approach 1:
The register mapper is divided into two separate structures: unified main mapper and intermediate register mapper. The unified main mapper holds entries until instruction completion (ensuring correctness), while the intermediate register mapper temporarily holds finished-but-not-completed entries (enabling earlier reuse). This segmentation allows each mapper to serve its specific function without compromising the other.
Solution Approach 2:
The intermediate register mapper acts as an intermediary between the unified main mapper and the execution pipeline. It receives mapper entries from the unified main mapper when instructions finish executing, allows earlier reuse of these entries, and ensures correctness is maintained until actual completion. This intermediary structure resolves the conflict between early reuse and correctness assurance.
2Productivity
If unified main mapper entries are released earlier, then mapper entry reuse increases and pipeline efficiency improves, but resource constraints are not fully addressed
Solution Approach 1:
The register mapper is divided into two separate structures: unified main mapper and intermediate register mapper. The unified main mapper holds entries until instruction completion (ensuring correctness), while the intermediate register mapper temporarily holds finished-but-not-completed entries (enabling earlier reuse). This segmentation allows each mapper to serve its specific function without compromising the other.
Solution Approach 2:
The intermediate register mapper acts as an intermediary between the unified main mapper and the execution pipeline. It receives mapper entries from the unified main mapper when instructions finish executing, allows earlier reuse of these entries, and ensures correctness is maintained until actual completion. This intermediary structure resolves the conflict between early reuse and correctness assurance.
3Productivity
If intermediate register mapper is introduced, then pipeline efficiency increases and resource constraints are optimized, but die area and device complexity increase
Solution Approach 1:
The register mapper is divided into two separate structures: unified main mapper and intermediate register mapper. The unified main mapper holds entries until instruction completion (ensuring correctness), while the intermediate register mapper temporarily holds finished-but-not-completed entries (enabling earlier reuse). This segmentation allows each mapper to serve its specific function without compromising the other.
Solution Approach 2:
The intermediate register mapper acts as an intermediary between the unified main mapper and the execution pipeline. It receives mapper entries from the unified main mapper when instructions finish executing, allows earlier reuse of these entries, and ensures correctness is maintained until actual completion. This intermediary structure resolves the conflict between early reuse and correctness assurance.
Data Source
AI summary
A prefix instruction is executed and passes operands to a net instruction without storing the operands in an architected resource such that the execution of the next instruction uses the operands provided by the prefix instruction to perform an operation, the operands may be prefix instruction immediate field or a target register of the prefix instruction execution.