Unified Data Hazard Resolution Unit for Processor Area Reduction
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Solution Overview
Problem
Conventional processors require separate logic and priority pickers to resolve read-after-write (RAW) and overeager read (OEL) data hazards, occupying valuable area and increasing complexity.
Innovation Solution
Implementing a single priority picker and shared logic to identify memory operations for both RAW and OEL hazards, utilizing order information manipulation to indicate memory operations' characteristics, thereby reducing area consumption and pipeline stages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate logic and priority pickers are used to resolve RAW and OEL data hazards, then data hazard resolution accuracy is improved, but processor area consumption increases
Solution Approach 1:
The patent merges separate RAW and OEL hazard resolution logic into a unified data hazard resolution unit. A single priority picker handles both RAW (read-after-write) and OEL (overeager load) hazards by selectively identifying dependent memory operations based on the hazard type, eliminating the need for duplicate logic blocks and reducing processor area while maintaining comprehensive hazard detection capability
Solution Approach 2:
The unified data hazard resolution unit performs multiple functions: it detects both RAW and OEL hazards, selects appropriate memory operations for each hazard type, and manages resolution through a single priority picker. This multi-functional approach allows one logic block to replace what would traditionally require separate dedicated units for each hazard type
2Measurement precision
If separate priority pickers are used for RAW and OEL hazards, then hazard detection precision is improved, but device complexity increases
Solution Approach 1:
The priority picker dynamically adapts its behavior based on the type of data hazard being resolved. For RAW hazards, it selects older store instructions; for OEL hazards, it selects younger store instructions. This dynamic selection capability allows a single static logic block to perform what would otherwise require multiple specialized units, reducing overall device complexity while preserving detection precision
3Reliability
If conventional separate logic is used for data hazard resolution, then data dependency preservation is improved, but processor area available for other purposes decreases
Solution Approach 1:
By merging RAW and OEL hazard resolution into a single unified unit with one priority picker, the patent frees up significant processor area that would have been occupied by duplicate logic blocks. This consolidated approach maintains complete data dependency preservation for both hazard types while making valuable processor real estate available for other functional units and optimizations
Data Source
AI summary
Order indication logic can be recycled for at least two different data hazards, thus reducing the amount of processor real estate consumed by data hazard resolution logic. The logic also allows a single priority picker to be utilized for coloring without the cost of additional pipeline stages. A single priority picker can be utilized to identify memory operations for performing RAW bypass and for resolving OERs. For instance, a data hazard resolution unit resolves at least two different data hazards between resident memory operations and incoming memory operations with a set of logic that indicates order of the resident memory operations relative to the incoming memory operations. The indicated order corresponds to the data hazard being resolved. The data hazard resolution unit includes a priority picker to select one of the indicated resident memory operations for either data hazard.