Fused Complex Multiply-Add Instruction for Vector Processing
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Solution Overview
Problem
Existing processor instruction set architectures for high-performance computing face inefficiencies in performing complex multiplication and accumulation operations, leading to high register file pressure, memory pressure, and power consumption due to the need for multiple instructions.
Innovation Solution
The introduction of fused complex multiplication and addition instructions that reduce resource usage by performing multiplication of two vectors of complex numbers and accumulation in a single instruction, with options for conjugation and various precision implementations, allowing for reduced register and memory pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple separate instructions are used for complex multiplication and accumulation, then operational flexibility is maintained, but register file pressure increases and power consumption rises
Solution Approach 1:
The patent combines complex multiplication and accumulation operations into a single fused instruction (VCFMADD). This merging eliminates the need for separate multiply and add instructions, reducing the number of instructions executed and thereby lowering power consumption while maintaining full operational flexibility through configurable operands and destinations.
Solution Approach 2:
The fused complex multiply-add instruction serves multiple functions simultaneously: it performs complex multiplication, complex accumulation, and supports both vector and scalar operations. The instruction can operate on packed complex data elements with configurable vector lengths, providing universal functionality that replaces multiple specialized instructions.
2Measurement precision
If multiple separate instructions are used for complex multiplication and accumulation, then instruction precision is maintained, but the number of required instructions increases
Solution Approach 1:
The patent merges complex multiplication and accumulation into a single atomic instruction that maintains full precision. The fused instruction performs both operations in one execution cycle without intermediate rounding or precision loss, achieving the same numerical accuracy as separate instructions but with half the instruction count.
3Measurement precision
If traditional complex arithmetic instructions are used, then computational accuracy is maintained, but memory pressure increases
Solution Approach 1:
The fused instruction combines multiply and add operations, allowing the processor to compute results and accumulate them directly in destination registers without storing intermediate multiplication results to memory. This eliminates temporary memory accesses while maintaining full computational accuracy through precise floating-point arithmetic.
Data Source
AI summary
Disclosed embodiments relate to executing a vector-complex fused multiply-add instruction. In one example, a method includes fetching an instruction, a format of the instruction including an opcode, a first source operand identifier, a second source operand identifier, and a destination operand identifier, wherein each of the identifiers identifies a location storing a packed data comprising at least one complex number, decoding the instruction, retrieving data associated with the first and second source operand identifiers, and executing the decoded instruction to, for each packed data element position of the identified first and second source operands, cross-multiply the real and imaginary components to generate four products: a product of real components, a product of imaginary components, and two mixed products, generate a complex result by using the four products according to the instruction, and store a result to the corresponding position of the identified destination operand.