Optimizing a Model using the Optimizer¶

Introduction¶

The ONNX Script Optimizer tool provides the user with the functionality to optimize an ONNX model by performing optimizations and clean-ups such as constant folding, dead code elimination, etc.

Usage¶

In order to utilize the optimizer tool,

import onnxscript

onnxscript.optimizer.optimize(model)

optimize API¶

The onnxscript.optimizer.optimize call takes in several optional parameters that allows the caller to further fine-tune the process of optimization.

onnxscript.optimizer.optimize(model: ModelProto, num_iterations: int = 2, *, onnx_shape_inference: bool = True, stop_if_no_change: bool = True, external_data_folder: str = '', **kwargs: Any) → ModelProto[source]

Optimize the model. Perform optimizations and clean-ups such as constant folding, dead code elimination, etc.

Parameters:

model (onnx.ModelProto) – The model to optimize.
num_iterations (int, optional) – Number of iterations to perform.
onnx_shape_inference (bool, optional) – Whether to perform onnx shape inference on the model. Set this to False to turn off onnx shape inference, and rely on model carried shapes and types. This is useful for models produced by PyTorch 2.2+ dynamo onnx exporter, where the model carries the symbolic shapes recorded from dynamo tracing.
stop_if_no_change (bool, optional) – Whether to stop if no change is detected.
external_data_folder (str, optional) – The folder to store external data.
**kwargs – Additional keyword arguments. For BC purposes.

Description of optimizations applied by `onnxscript.optimizer.optimize`¶

Optimization ‘onnxscript.optimizer.` + …	Description
Constant folding `constant_folding.fold_constants`	Applies constant folding optimization to the model.
Constant propagation `constant_folding.fold_constants`	Applies constant propagation optimization to the model. Applied as part of the constant folding optimization.
Sequence simplification `constant_folding.fold_constants`	Simplifies Sequence based ops (SequenceConstruct, ConcatFromSequence) present in the model. Applied as part of the constant folding optimization.
Remove unused nodes `remove_unused.remove_unused_nodes`	Removes unused nodes from the model.
Remove unused functions `remove_unused_function.remove_unused_functions`	Removes unused function protos from the model.
Inline functions with unused outputs `simple_function_folding.inline_functions_with_unused_outputs`	Inlines function nodes that have unused outputs.
Inline simple functions `simple_function_folding.inline_simple_functions`	Inlines simple functions based on a node count threshold.

List of pattern rewrite rules applied by `onnxscript.optimizer.optimize`¶

`onnxscript.rewriter.broadcast_to_matmul`
`onnxscript.rewriter.cast_constant_of_shape`
`onnxscript.rewriter.gemm_to_matmul_add`
`onnxscript.rewriter.no_op`