Vector Processing Unit Lane Skip Indicators
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Solution Overview
Problem
Existing vector processing units face challenges in efficiently performing conditional operations across multiple lanes of parallel processing, leading to reduced performance due to the complexity of encoding conditionality within vector instructions, which often results in the use of scalar operations instead.
Innovation Solution
A data processing apparatus and method that utilizes skip indicators for each lane of parallel processing, allowing conditional execution of vector operations through a vector skip instruction that sets and manages skip indicators, enabling selective exclusion of lanes from operations without modifying the vector operation instructions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conditionality is encoded within vector instructions, then conditional execution within lanes is enabled, but instruction size increases significantly
Solution Approach 1:
The patent extracts the conditionality encoding from the vector operation instructions and places it in separate control registers (skip indicators and mask registers). This separation allows conditional execution to be controlled without increasing the size of vector operation instructions, as the control information is stored independently in register files rather than embedded in each instruction.
Solution Approach 2:
The patent prepares control information in advance by setting skip indicators and mask register values before executing vector operations. The conditionality is predetermined and stored in control registers, allowing the vector processing unit to automatically apply conditional logic during execution without needing complex encoding in each instruction.
2Adaptability or versatility
If scalar operations are used instead of vector operations for conditional execution, then conditional logic is achieved, but performance significantly decreases
Solution Approach 1:
The patent applies conditional execution locally to individual lanes rather than requiring global scalar processing. Each lane can independently evaluate conditions through its own skip indicator and mask register, allowing parallel conditional execution across multiple lanes. This maintains vector processing performance while enabling conditional logic where needed in specific lanes.
Solution Approach 2:
The patent creates a universal control mechanism that works across all vector operations and lanes. The skip indicators and mask registers provide a unified interface for conditional execution that can be applied to any vector operation, eliminating the need for separate scalar processing paths and maintaining performance across different operation types.
3Productivity
If vector processing unit is used for parallel processing, then performance benefits are achieved, but conditional execution within lanes becomes complex
Solution Approach 1:
The patent segments the control of conditional execution into separate components: skip indicators for each lane, mask registers for condition selection, and control logic for evaluating conditions. This segmentation simplifies the overall control structure by breaking down complex conditional execution into manageable, independent elements that can be controlled separately for each lane.
Solution Approach 2:
The patent introduces mask registers as intermediary structures between the control logic and the execution units. These mask registers act as mediators that translate high-level conditional requirements into lane-specific control signals, simplifying the interface between control logic and execution units while enabling flexible conditional execution across all lanes.
Data Source
AI summary
A data processing apparatus and method and provided for handling vector instructions. The data processing apparatus has a register data store with a plurality of registers arranged to store data elements. A vector processing unit is then used to execute a sequence of vector instructions, with the vector processing unit having a plurality of lanes of parallel processing and having access to the register data store in order to read data elements from, and write data elements to, the register data store during the execution of the sequence of vector instructions. A skip indication storage maintains a skip indicator for each of the lanes of parallel processing. The vector processing unit is responsive to a vector skip instruction to perform an update operation to set within the skip indication storage the skip indicator for a determined one or more lanes. The vector processing unit is responsive to a vector operation instruction to perform an operation in parallel on data elements input to the plurality of lanes of parallel processing, but to exclude from the performance of the operation any lane whose associated skip indicator is set. This allows the operation specified by vector instructions to be performed conditionally within each of the lanes of parallel processing without any modification to the vector instructions that are specifying those operations.