Unified Store Buffer for Processor Pipeline Stalls
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Solution Overview
Problem
Modern processors face inefficiencies due to separate pre-commit and post-commit store buffers, leading to resource underutilization and potential pipeline stalls when the memory subsystem is occupied, as the post-commit structure becomes full while the pre-commit structure has available space.
Innovation Solution
A unified store buffer is introduced to store data for both pre-commit and post-commit store instructions, allowing for efficient use of buffer resources by accommodating either type of instruction, thereby reducing the likelihood of pipeline stalls and optimizing die space and power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate pre-commit and post-commit store buffers are used, then store instructions can be processed according to their commitment status, but resource utilization decreases and pipeline stalls increase when the memory subsystem is occupied
Solution Approach 1:
The patent merges separate pre-commit and post-commit store buffers into a single unified store buffer. The buffer accepts store instructions with a commitment status indicator, allowing both pre-commit and post-commit instructions to share the same storage resource. This eliminates the problem where the post-commit buffer becomes full while the pre-commit buffer has available space, thereby improving resource utilization and reducing pipeline stalls.
Solution Approach 2:
The unified store buffer serves multiple functions by accommodating both pre-commit and post-commit store instructions within the same structure. The buffer can dynamically allocate space to either type of instruction based on availability, making the storage resource universal and adaptable to different commitment states, thus preventing resource underutilization.
2Reliability
If separate pre-commit and post-commit store buffers are used, then store instructions can be processed according to their commitment status, but die space and power consumption increase
Solution Approach 1:
The patent merges separate pre-commit and post-commit store buffers into a single unified store buffer. The buffer accepts store instructions with a commitment status indicator, allowing both pre-commit and post-commit instructions to share the same storage resource. This eliminates the problem where the post-commit buffer becomes full while the pre-commit buffer has available space, thereby improving resource utilization and reducing pipeline stalls.
Solution Approach 2:
The unified store buffer serves multiple functions by accommodating both pre-commit and post-commit store instructions within the same structure. The buffer can dynamically allocate space to either type of instruction based on availability, making the storage resource universal and adaptable to different commitment states, thus preventing resource underutilization.
Data Source
AI summary
Techniques are disclosed relating to speculative execution of store instructions. In various embodiments, an integrated circuit includes an execution pipeline having a load store circuit. The load store circuit is configured to receive a first store instruction executable to store a first value in a memory accessible to the integrated circuit. Prior to the first store instruction committing, the load store circuit stores the first value in a store buffer. In response to the first store instruction committing, the load store circuit stores, in the store buffer, an indication that the first store instruction has committed. In various embodiments, the integrated circuit reads the stored indication to determine whether the first store instruction has committed and, responsive to the read indication, provides the first value for storage in the memory.