Bias fails to broadcast in the context of matmul in tf lite model

[gaikwadrahul8]

1. System information

• OS Platform and Distribution (e.g., Linux Ubuntu 16.04): Linux Ubuntu 20.04
• TensorFlow installation (pip package or built from source): pip
• TensorFlow library (version, if pip package or github SHA, if built from source): 2.14.0-dev20230602

2. Code

This is the minimized code to reproduce the issue:

import tensorflow as tf
import numpy as np

x1 = tf.constant([1., 2.], shape=[1, 2])

class Model(tf.keras.Model):
  def __init__(self):
    super(Model, self).__init__()
    self.w = tf.Variable([[3., 4.], [5., 6.]])
    self.b = tf.Variable([3.])
  @tf.function(input_signature=[tf.TensorSpec(x1.shape, x1.dtype)])
  def call(self, x):
    return tf.matmul(x, self.w) + self.b


m = Model()
print('Keras mode output: ', m(x1).numpy())

converter = tf.lite.TFLiteConverter.from_keras_model(m)
tflite_model = converter.convert()
def _evaluateTFLiteModel(tflite_model, input_data):
    interpreter = tf.lite.Interpreter(model_content=tflite_model)
    interpreter.allocate_tensors()

    input_details = interpreter.get_input_details()
    output_details = interpreter.get_output_details()

    for i in range(len(input_data)):
        interpreter.set_tensor(input_details[i]['index'], input_data[i])

    interpreter.invoke()

    output_data = [interpreter.get_tensor(output_details[i]['index'])
                   for i in range(len(output_details))]
    return output_data

print('Lite mode output: ', _evaluateTFLiteModel(tflite_model,[x1])[0])

3. Failure after conversion

Output:

Keras mode output: [[16. 19.]]
Lite mode output:  RuntimeError: tensorflow/lite/kernels/fully_connected.cc:360 NumElements(bias) != SizeOfDimension(filter, 0) (1 != 2)Node number 0 (FULLY_CONNECTED) failed to prepare.Failed to apply the default TensorFlow Lite delegate indexed at 0.

Conversion Failure:

• During conversion, the model fails due to the following check at tensorflow/lite/kernels/fully_connected.cc:360

if (bias) {
    TF_LITE_ENSURE_EQ(context, NumElements(bias), SizeOfDimension(filter, 0));
  }

[gaikwadrahul8]

This issue originally reported by @YaoJiayi has been moved to this dedicated repository for LiteRT to enhance issue tracking and prioritization. To ensure continuity, we have created this new issue on your behalf.

We appreciate your understanding and look forward to your continued involvement.

[pkgoogle]

Original Issue: tensorflow/tensorflow#60929