Hi, I am struggling for several hours with the following issue:
I’ve got a lstm model in pytorch that I want to convert to TVM. Here is the
sample code of the model. It includes one lstm layer. From what I’ve found
until now, TVM does not support yet LSTM operators if converting from pytorch
directly. Therefore I’ve tried to convert my model first to ONNX and then
convert it to TVM, but the conversion doesn't work well.
Here is the code.
```Python:convert_lstm.py
import torch
import torch.nn as nn
import numpy as np
import onnxruntime as ort
import onnx
import tvm
import tvm.relay as relay
from tvm.contrib import graph_runtime
from IPython import embed
num_layers = 3
num_hyperparams = 4
batch = 1
hidden_size = 20
def to_numpy(tensor):
return tensor.detach().numpy()
class My_LSTM(nn.Module):
def __init__(self, num_hyperparams, hidden_size, num_layers):
super(My_LSTM, self).__init__()
self.lstm = nn.LSTM(input_size=num_hyperparams,
hidden_size=hidden_size,
num_layers=num_layers)
def forward(self, input, hn, cn):
output, (hn, cn) = self.lstm(input, (hn, cn))
return output, hn, cn
model = My_LSTM(num_hyperparams, hidden_size, num_layers)
input = torch.randn(1, batch, num_hyperparams)
h0 = torch.zeros(num_layers, batch, hidden_size)
c0 = torch.zeros(num_layers, batch, hidden_size)
loop_num = 5
hn = h0
cn = c0
output_torch = []
for i in range(loop_num):
output, hn, cn = model(input, hn, cn)
output_torch.append(to_numpy(output[0]))
onnx_path = 'temp.onnx'
dummy_input = torch.randn(1, batch, num_hyperparams)
dummy_h0 = torch.randn(num_layers, batch, hidden_size)
dummy_c0 = torch.randn(num_layers, batch, hidden_size)
torch.onnx.export(model,
(dummy_input, dummy_h0, dummy_c0),
onnx_path,
input_names=['input','h0','c0'],
output_names=['output', 'hn', 'cn'],
)
sess = ort.InferenceSession(onnx_path)
input_names = [item.name for item in sess.get_inputs()]
hn = to_numpy(h0)
cn = to_numpy(c0)
output_onnx = []
for i in range(loop_num):
output, hn, cn = sess.run(None,
{input_names[0]:to_numpy(input),
input_names[1]:hn,
input_names[2]:cn})
output_onnx.append(output[0])
onnx_model = onnx.load(onnx_path)
mod, params = relay.frontend.from_onnx(onnx_model)
with relay.build_config(opt_level=0):
graph, lib, params_run = relay.build(mod,
target = "llvm",
params=params)
ctx = tvm.cpu()
m = graph_runtime.create(graph, lib, ctx)
m.set_input(**params_run)
hn = to_numpy(h0)
cn = to_numpy(c0)
output_tvm = []
for i in range(loop_num):
m.set_input('input', to_numpy(input))
m.set_input('h0', hn)
m.set_input('c0', cn)
m.run()
output_tvm.append(m.get_output(0).asnumpy()[0])
hn=m.get_output(1)
cn=m.get_output(2)
for i in range(2):
print("loop = %d"%i)
print("Pytorch : %f"%output_torch[i][0,0])
print("OnnxRuntime : %f"%output_onnx[i][0,0])
print("TVM : %f"%output_tvm[i][0,0])
```
When you run this code, you will get output similar to the following:
loop = 0
Pytorch : -0.022901
OnnxRuntime : -0.022901
TVM : -0.022901
loop = 1
Pytorch : -0.027888
OnnxRuntime : -0.027888
TVM : -0.016093
This result indicates that if the LSTM has a hidden state of 0, the TVM works,
otherwise it does not work. How can I load the pytorch lstm model with tvm
properly?
My environment is below:
- OS: Ubuntu 18.04
- Pytorch: 1.6.0
- ONNX: 1.8.1
- TVM: 0.8.dev0
- onnxruntime: 1.7.0
Thank you.
---
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