Swizzle Sequence Instruction for Vector Data Element Shuffling
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Solution Overview
Problem
Conventional methods for shuffling elements of operand vectors in vector execution units lead to performance degradation due to register file occupation and read-after-write dependencies, causing pipeline stalls and increased code size.
Innovation Solution
Implementing sequential vector multiplexer control and a swizzle sequence instruction to selectively shuffle data elements for a sequence of vector instructions, allowing multiple instructions to use a common custom word ordering without requiring separate permute or swizzle instructions for each.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If separate permute or swizzle instructions are used for each vector instruction, then data element shuffling can be performed, but code size increases and pipeline stalls occur due to read-after-write dependencies
Solution Approach 1:
The patent combines the swizzle control functionality into the vector instruction itself by adding a swizzle control field to the vector instruction format. This merging eliminates the need for separate swizzle instructions before each vector operation, reducing code size and eliminating read-after-write dependencies while maintaining full data element shuffling capability.
Solution Approach 2:
The vector instruction is enhanced to serve multiple functions: it performs both the original vector operation and the data element shuffling operation simultaneously through the integrated swizzle control field. This multi-functionality allows a single instruction to replace what previously required multiple separate instructions.
2Ease of operation
If separate permute or swizzle instructions are used for each vector instruction, then data element shuffling can be performed, but pipeline stalls occur due to register file occupation and read-after-write dependencies
Solution Approach 1:
By merging the swizzle control into the vector instruction, the patent eliminates the need for separate swizzle instructions that would occupy register files and create read-after-write dependencies. This integration allows the pipeline to execute vector instructions with shuffling operations without stalls, maintaining continuous throughput.
Solution Approach 2:
The swizzle control parameters are prepared and embedded within the vector instruction itself before execution begins. This preliminary preparation of shuffling control data within the instruction eliminates the need for separate preparation instructions that would otherwise cause pipeline stalls.
3Ease of operation
If conventional swizzle instructions are used, then data element ordering can be changed, but register file usage increases
Solution Approach 1:
The patent merges the swizzle control parameters directly into the vector instruction structure through the swizzle control field. This integration eliminates the need for separate register storage of swizzle control data, reducing register file usage while maintaining full data element permutation capability.
Data Source
AI summary
Operand vector multiplexer sequence control is used in a vector-based execution unit to control the shuffling of data elements in operand vectors used by a sequence of vector instructions processed by the vector-based execution unit. A swizzle sequence instruction is defined in an instruction set for the vector-based execution unit and is used to selectively apply a sequence of vector data element shuffle orders to one or more operand vectors to be used by the associated sequence of vector instructions. As a result, when a common sequence of data element shuffle orders is used frequently for a sequence of vector instructions, a single swizzle sequence instruction may be used to select the desired sequence of custom data element ordering for each of the vector instructions in the sequence.