Unary Fusion Patterns

Unary Fusion Patterns#

Overview#

oneDNN supports various unary fusion patterns to optimize performance and reduce memory bandwidth requirements. This document describes the supported fusion patterns for Unary operations.

Pattern Structure#

oneDNN defines floating-point Unary fusion patterns as follows. The blue nodes are required when defining a Unary fusion pattern while the brown nodes are optional.

Unary pattern

  1. Unary Operation : Performs the corresponding unary operation for the src tensor. Refer to the Note in Fusion Patterns.

  2. Epilogue Subgraph : Optional and can include the following operations:

    • Unary operations.

    • Binary operations: refer to the Note in Fusion Patterns.

    Combination Rules:

    epilogue subgraph

    • N=20, 0 to 20 Binary or Unary operations are supported in the epilogue subgraph.

Data Types#

oneDNN supports the following combinations of data types for src and dst:

src

dst

f32,bf16,f16

f32,bf16,f16

The definition of the data types and support status on different CPU and GPU platforms follow the general description in the Data Types Guide.

Implementation Notes#

Post-binary Add operations in the epilogue subgraph support in-place operations when the post-binary Add is the last operation in the epilogue subgraph and the dst output shape is identical and data type size is the same as the binary Add input. In case of an in-place operation, the original input data will be overwritten. Use in-place operations whenever possible for performance.

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