Fusion Buffer Operand Handling for Write-Port-Limited Processors
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Solution Overview
Problem
Modern processors face performance issues when executing instructions that generate large operands, such as vector or matrix operations, due to increased latency, pipeline congestion, and resource consumption, particularly in write-port-limited processors.
Innovation Solution
The use of a fusion buffer to store storage instruction operations until a buffer vacate condition is detected, allowing the instructions to be dropped or fused with consumer instructions without writing to destination registers, thereby optimizing execution and reducing resource consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If storage instruction operations are executed to generate large operands, then the required operand values are produced, but register writes cause pipeline congestion and increased latency in write-port-limited processors
Solution Approach 1:
The fusion buffer acts as an intermediary between the storage instruction operation and the consumer instructions. Instead of directly writing large operands to destination registers (which causes pipeline congestion), the buffer temporarily holds the operand values and enables fused execution where consumer instructions read directly from the buffer, eliminating the need for register writes and reducing latency.
Solution Approach 2:
The invention merges the storage instruction operation with subsequent consumer instructions into a single fused execution unit. This combining allows the storage operation to generate large operands while consumer instructions simultaneously read from the fusion buffer, eliminating the sequential register write/read bottleneck and improving execution throughput.
2Reliability
If storage instruction operations write to destination registers, then operands are made available for consumer instructions, but write-port limited processors experience resource consumption constraints
Solution Approach 1:
The fusion buffer serves as an intermediary that decouples the storage instruction from the consumer instructions. The buffer holds the generated operands and enables consumer instructions to read directly from it, eliminating the need to compete for write ports and reducing the complexity of write-port managed resource allocation.
Solution Approach 2:
The fusion buffer is prepared in advance to hold storage instruction operations before consumer instructions arrive. This preliminary buffering allows the system to pre-generate operands without immediately writing to registers, smoothing out the timing constraints imposed by write-port limitations.
3Adaptability or versatility
If large operands are generated for vector or matrix operations, then computational capability is enhanced, but latency and resource consumption increase
Solution Approach 1:
By merging storage instructions with consumer instructions into fused execution units that operate simultaneously on the fusion buffer, the system can generate and consume large operands in parallel. This eliminates the sequential latency of generating operands, writing to registers, then reading from registers for consumer instructions.
Data Source
AI summary
Techniques are disclosed involving operand management using a fusion buffer. A processor includes operand management circuitry, where the operand management circuitry includes a fusion buffer, and execution circuitry. In one embodiment, the operand management circuitry is configured to detect a first storage instruction operation that is executable to store operand values usable by one or more consumer instruction operations and store the first storage instruction operation in the fusion buffer. In response to detecting a drop condition associated with the first storage instruction operation, the operand management circuitry is configured to remove the first storage instruction operation from the fusion buffer without forwarding the first storage instruction operation for execution. In response to detecting a buffer vacate condition and not detecting the drop condition the operand management circuitry is configured to forward the first storage instruction operation for execution by the execution circuitry.