02_folding_constants

Using Sanitize To Fold Constants

Introduction

The surgeon sanitize subtool can be used to fold constants in graphs, remove unused nodes, and topologically sort nodes. In cases where shapes are statically known, it can also simplify subgraphs involving shape operations.

In this example, we'll fold constants in a graph that computes output = input + ((a + b) + d), where a, b, and d are constants:

Running The Example

1. Fold constants with:

   polygraphy surgeon sanitize model.onnx \
       --fold-constants \
       -o folded.onnx

   This collapses a, b, and d into a constant tensor, and the resulting graph computes output = input + e:

   

2. [Optional] You can use inspect model to confirm whether it looks correct:

   polygraphy inspect model folded.onnx --show layers