[BUG] The pass "eliminate_nop_expand" causes output mismatch

[BUG] The pass "eliminate_nop_expand" causes output mismatch

Issue
Running the single pass eliminate_nop_expand with onnxoptimizer 0.4.2 changes numerical outputs.

Environment

• Ubuntu 20.04
• Python 3.10
• onnx==1.19.0
• onnxruntime==1.23.2
• onnxoptimizer==0.4.2(latest)

Repro steps (run from this folder)

1. Create a Python environment (Python 3.10) and install dependencies:

python3 -m venv .venv
source .venv/bin/activate
pip install -U pip
pip install -r requirements.txt

2. Optimize a case with only eliminate_nop_expand (writes model.opt.onnx next to model.onnx):

• python optimize_model.py --case ./case_08971_seed91292368

3. Differential test original and optimized models with same oracle inputs (ORT graph optimization disabled):

• python diff_test.py --case ./case_08971_seed91292368

Expected
eliminate_nop_expand should be semantics-preserving. Applying this pass alone should not change any output values.

Differential Test Output Details

1. case_08971_seed91292368 — output[1] max_abs=6.000e+00 max_rel=6.000e+08; output[5] max_abs=1.000e+00 max_rel=1.000e+00; overall mismatch.

Case: case_08971_seed91292368
  output[0]: max_abs=0.000e+00, max_rel=0.000e+00, shape=(1, 55, 1, 1, 1)
  output[1]: max_abs=6.000e+00, max_rel=6.000e+08, shape=(2, 55, 2, 1, 2)
  output[2]: max_abs=0.000e+00, max_rel=0.000e+00, shape=(2, 55, 2, 1, 2)
  output[3]: max_abs=0.000e+00, max_rel=0.000e+00, shape=(41, 55, 2, 1, 2)
  output[4]: max_abs=0.000e+00, max_rel=0.000e+00, shape=(41, 55, 2, 1, 6)
  output[5]: max_abs=1.000e+00, max_rel=1.000e+00, shape=(41, 55, 2, 1, 6)
  output[6]: max_abs=0.000e+00, max_rel=0.000e+00, shape=(40590,)
  output[7]: max_abs=0.000e+00, max_rel=0.000e+00, shape=(1,)
  output[8]: max_abs=0.000e+00, max_rel=0.000e+00, shape=(1, 1)
  output[9]: max_abs=0.000e+00, max_rel=0.000e+00, shape=(1,)
  output[10]: max_abs=0.000e+00, max_rel=0.000e+00, shape=(1, 1)
  output[11]: max_abs=0.000e+00, max_rel=0.000e+00, shape=(1,)
  output[12]: max_abs=0.000e+00, max_rel=0.000e+00, shape=(41, 55, 18, 1)
  output[13]: max_abs=0.000e+00, max_rel=0.000e+00, shape=(41, 55, 18, 1)
  output[14]: max_abs=0.000e+00, max_rel=0.000e+00, shape=(41, 55, 1, 1)
  output[15]: max_abs=0.000e+00, max_rel=0.000e+00, shape=(41, 55, 1, 1)
Overall: max_abs=6.000e+00, max_rel=6.000e+08

Attachments

• requirements.txt
• optimize_model.py
• diff_test.py (runs original and optimized with same oracle inputs; ORT graph optimizations disabled)
• run_optimized_model.py (executes optimized model with oracle inputs)
• case_08971_seed91292368/ (original model and oracle inputs)

Start by running optimize_model.py and diff_test.py for case_08971_seed91292368 with the listed dependencies, then inspect the eliminate_nop_expand pass and the attached model. Compare the original and optimized outputs, especially output[1] and output[5]. Done means the pass preserves all reported output values.