GraphProto loses its sparse tensor initializer going through the optimizer.

[jxchenus]

Bug Report

Is the issue related to model conversion?

No.

Describe the bug

Start with an ONNX model with a sparse initializer. Run model optimizer with option "eliminate_unused_initializer". Now the returned model no longer has the original sparse initializer.

System information

• OS Platform and Distribution (e.g. Linux Ubuntu 16.04): Linux RedHat5
• ONNX version (e.g. 1.7): 1.6
• Python version: 3.8.2
• GCC/Compiler version (if compiling from source): gcc7
• CMake version:
• Protobuf version: 3
• Visual Studio version (if applicable):

Reproduction instructions

• Describe the code to reproduce the behavior.

  import onnx
  from onnx import optimizer
  model = onnx.load('model.onnx')
  model.graph.sparse_initializer
  optimized_model = optimizer.optimize(model)
  optimized_model.graph.sparse_initializer

• Attach the ONNX model to the issue (where applicable) A text version of the ONNX model is attached.

Expected behavior

The sparse initializer should persist in the optimized model.

Notes

When the optimizer converts GraphProto to onnx::Graph in the following stack, the sparse initializer is not carried over:

0 onnx::graphProtoToGraph (gp=..., nested=nested@entry=false)

at .../onnx/common/ir_pb_converter.cc:188 onnx/onnx#1 0x0000000000568d3f in onnx::ImportModelProto (mp=...) at .../onnx/common/ir_pb_converter.cc:338 onnx/onnx#2 0x000000000054e39a in onnx::optimization::Optimizer::optimize ( this=this@entry=0x7fffffffcf00, mp_in=...) at .../onnx/optimizer/optimize.h:26 onnx/onnx#3 0x0000000000534d3c in onnx::optimization::Optimize (mp_in=..., names=...) at .../onnx/optimizer/optimize.cc:32 rank2-identity.txt

[askhade]

ONNX optimizers are now being moved to a standalone repo under onnx tree. Please open this issue here : https://github.com/onnx/optimizer

[jxchenus]

Thanks for the update!

I'm not sure whether this is an ONNX specific issue, as the fix for it involves adding Sparse Tensor to onnx::Graph and the encoding and decoding logic in ir_pb_converter.cc.