This diagnostic tracks the FX passes executed during the ONNX export process prior to converting from FX IR (Intermediate Representation) to ONNX IR.

Under the scope of ONNX export, an FX pass refers to a specific transformation applied to the FX GraphModule. The primary aim of these passes is to streamline the graph into a format that aligns more with the ONNX IR. Moreover, these passes work to substitute unsupported FX IR features with those recognized and endorsed by ONNX IR. Common transformations include, but aren’t limited to, decomposition, functionalization and type promotion.

For those who are interested in a comprehensive log detailing the modifications made during these passes, there are a couple of options:

  • Set DiagnosticOptions.verbosity_level to logging.DEBUG.

  • Activate the environment variable TORCH_LOGS=’onnx_diagnostics’.

However, it’s noteworthy that by default, such detailed logging is turned off. The primary reason being its considerable impact on performance.

For an in-depth understanding of each specific pass, please refer to the directory: torch/onnx/_internal/fx/passes.


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