Mixed-Width SIMD Instruction Using Register Pair for Even and Odd Elements
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Solution Overview
Problem
Conventional mixed-width SIMD instructions require decomposition into multiple component instructions, leading to increased code size and power wastage due to unnecessary data movements and hardware requirements.
Innovation Solution
A single mixed-width SIMD instruction is implemented, where one vector operand is expressed as a pair of registers and the other as a single register, allowing efficient execution by minimizing data movement across SIMD lanes and reducing code size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If mixed-width SIMD operations are implemented using conventional approaches, then the operations can be executed, but code size increases and power is wasted due to multiple component instructions
Solution Approach 1:
The patent combines multiple component SIMD instructions into a single mixed-width SIMD instruction that can operate on both even-numbered and odd-numbered data elements simultaneously. This merging eliminates the need for separate instructions, reducing code size while maintaining the capability to handle mixed-width operations efficiently
Solution Approach 2:
The invention creates a universal SIMD instruction format that can handle multiple data element widths (e.g., 8-bit, 16-bit, 32-bit) within a single instruction. This multi-functional instruction replaces multiple specialized instructions, reducing overall code size and improving execution efficiency
2Productivity
If mixed-width SIMD operations use multiple component instructions, then all data elements can be processed, but data movement across SIMD lanes increases
Solution Approach 1:
The patent segments the data elements within a single SIMD instruction into even-numbered and odd-numbered groups, allowing each group to be processed independently but simultaneously. This segmentation enables efficient data movement by keeping related data elements in their respective lanes without requiring additional cross-lane movements that would occur with multiple sequential instructions
3Ease of operation
If conventional SIMD instructions are used with uniform data elements, then execution is simple, but mixed-width operations require complex decomposition
Solution Approach 1:
The patent introduces an asymmetric instruction format where a single mixed-width SIMD instruction inherently handles different data element widths (e.g., some 8-bit elements and some 16-bit elements) within the same operation. This asymmetric design eliminates the need for symmetric decomposition into multiple uniform-width instructions, simplifying the operation while reducing complexity
Data Source
Figure 1A~1B
Figure 1C
Figure 2A~2B
AI summary
Systems and methods relate to a mixed-width single instruction multiple data (SIMD) instruction which has at least a source vector operand comprising data elements of a first bit-width and a destination vector operand comprising data elements of a second bit-width, wherein the second bit-width is either half of or twice the first bit-width. Correspondingly, one of the source or destination vector operands is expressed as a pair of registers, a first register and a second register. The other vector operand is expressed as a single register. Data elements of the first register correspond to even-numbered data elements of the other vector operand expressed as a single register, and data elements of the second register correspond to data elements of the other vector operand expressed as a single register.