Vector Permute Logic with Control Register and Immediate Matching
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Solution Overview
Problem
Current processor architectures face challenges in efficiently performing vector permute operations with an index and immediate, particularly in implementing table lookups for high-performance computing workloads, due to limitations in existing instruction set architectures and microarchitectures.
Innovation Solution
The introduction of a vector friendly instruction format that includes specific fields for vector operations, such as the immediate field, allows for efficient vector permute operations by matching the most significant bits of control register elements with the least significant bits of an immediate value, enabling efficient data element swapping and copying between source and destination registers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional instruction set architectures are used for vector permute operations, then device compatibility is maintained, but processing efficiency and performance are insufficient
Solution Approach 1:
The instruction is divided into multiple fields including opcode field, source register field, destination register field, control register field, and immediate field. Each field serves a specific function in the vector permute operation, allowing complex operations to be broken down into manageable components that can be processed efficiently
Solution Approach 2:
The control register is pre-loaded with control data elements containing index values and match criteria before the permute operation executes. This preliminary preparation allows the execution unit to perform rapid comparisons and selections without computing these values during the actual permute operation, thereby improving processing efficiency
2Measurement precision
If vector permute operations are implemented without immediate values, then instruction simplicity is maintained, but control precision over data element permutation is insufficient
Solution Approach 1:
The immediate field provides localized control precision for specific aspects of the permute operation (matching control data elements with immediate values), while other fields handle different aspects of the operation. This allows precise control where needed without adding complexity to the entire instruction format
Solution Approach 2:
The control register serves multiple functions: it stores index values for selecting source data elements, stores match criteria for comparing with immediate values, and controls which source elements are copied to destination elements. This multi-functionality provides precise control without requiring separate instructions for each function
3Speed
If existing instruction formats are used for table lookups, then instruction compatibility is maintained, but processing speed is insufficient for high-performance computing
Solution Approach 1:
The control register is pre-loaded with control data elements containing index values and match criteria before the permute operation executes. This preliminary preparation allows the execution unit to perform rapid comparisons and selections without computing these values during the actual permute operation, thereby improving processing speed
Solution Approach 2:
The execution unit dynamically compares control data elements with immediate values and selectively copies source data elements to destination elements based on match results. This dynamic selection process enables fast table lookups by directly mapping control values to source elements without sequential processing
Data Source
Figure 1A
Figure 1B
Figure 2A~2C
AI summary
An apparatus and method for performing a vector permute. For example, one embodiment of a processor comprises: a source vector register to store a plurality of source data elements; a destination vector register to store a plurality of destination data elements; a control vector register to store a plurality of control data elements, each control data element corresponding to one of the destination data elements and including an N bit value indicating whether a source data element is to be copied to the corresponding destination data element; vector permute logic to compare the N bit value of each control data element to an N bit portion of an immediate to determine whether to copy a source data element to the corresponding destination data element, wherein if the N bit values match, then the vector permute logic is to identify a source data element using an index value included in the control data element and to responsively copy the source data element to the corresponding destination data element in the destination vector register.