Add support for masking and groups in QConv2D.

PiperOrigin-RevId: 726258359
Change-Id: I565b1fec70fa3007246111725aeff936f54a1c0d

Author: Akshaya Purohit

qkeras/qconvolutional.py

@@ -16,8 +16,10 @@
 from __future__ import absolute_import
 from __future__ import division
 from __future__ import print_function
+
 import warnings
 
+import numpy as np
 import tensorflow as tf
 from tensorflow.keras import constraints
 from tensorflow.keras import initializers
@@ -26,19 +28,19 @@
 from tensorflow.keras.layers import Conv1D
 from tensorflow.keras.layers import Conv2D
 from tensorflow.keras.layers import Conv2DTranspose
-from tensorflow.keras.layers import SeparableConv1D
-from tensorflow.keras.layers import SeparableConv2D
 from tensorflow.keras.layers import DepthwiseConv2D
 from tensorflow.keras.layers import Dropout
 from tensorflow.keras.layers import InputSpec
-from tensorflow.python.eager import context
-from tensorflow.python.ops import array_ops
-# from tensorflow.python.ops import array_ops
+from tensorflow.keras.layers import SeparableConv1D
+from tensorflow.keras.layers import SeparableConv2D
+
 from .qlayers import get_auto_range_constraint_initializer
 from .qlayers import QActivation
 from .quantizers import get_quantized_initializer
 from .quantizers import get_quantizer
-
+from tensorflow.python.eager import context
+from tensorflow.python.ops import array_ops
+# from tensorflow.python.ops import array_ops
 from tensorflow_model_optimization.python.core.sparsity.keras.prunable_layer import PrunableLayer
 
 
@@ -260,32 +262,36 @@ class QConv2D(Conv2D, PrunableLayer):
   #   can go over [-1,+1], these values are used to set the clipping
   #   value of kernels and biases, respectively, instead of using the
   #   constraints specified by the user.
+  # mask: Optional mask for kernel weights.
   #
   # we refer the reader to the documentation of Conv2D in Keras for the
   # other parameters.
   #
 
-  def __init__(self,
-               filters,
-               kernel_size,
-               strides=(1, 1),
-               padding="valid",
-               data_format="channels_last",
-               dilation_rate=(1, 1),
-               activation=None,
-               use_bias=True,
-               kernel_initializer="he_normal",
-               bias_initializer="zeros",
-               kernel_regularizer=None,
-               bias_regularizer=None,
-               activity_regularizer=None,
-               kernel_constraint=None,
-               bias_constraint=None,
-               kernel_range=None,
-               bias_range=None,
-               kernel_quantizer=None,
-               bias_quantizer=None,
-               **kwargs):
+  def __init__(
+      self,
+      filters,
+      kernel_size,
+      strides=(1, 1),
+      padding="valid",
+      data_format="channels_last",
+      dilation_rate=(1, 1),
+      activation=None,
+      use_bias=True,
+      kernel_initializer="he_normal",
+      bias_initializer="zeros",
+      kernel_regularizer=None,
+      bias_regularizer=None,
+      activity_regularizer=None,
+      kernel_constraint=None,
+      bias_constraint=None,
+      kernel_range=None,
+      bias_range=None,
+      kernel_quantizer=None,
+      bias_quantizer=None,
+      mask=None,
+      **kwargs,
+  ):
 
     if kernel_range is not None:
       warnings.warn("kernel_range is deprecated in QConv2D layer.")
@@ -324,6 +330,20 @@ def __init__(self,
     if activation is not None:
       activation = get_quantizer(activation)
 
+    if mask is not None:
+      shape = mask.shape
+      if len(shape) < 2:
+        raise ValueError(
+            "Expected shape to have rank at least 2 but provided shape has"
+            f" rank {len(shape)}"
+        )
+      h, w = shape[0], shape[1]
+      self._mask = np.reshape(
+          mask, (h, w, 1, 1)
+      )  # Extend the dimension to be 4D.
+    else:
+      self._mask = None
+
     super().__init__(
         filters=filters,
         kernel_size=kernel_size,
@@ -343,19 +363,44 @@ def __init__(self,
         **kwargs
     )
 
+  def convolution_op(self, inputs, kernel):
+    return tf.keras.backend.conv2d(
+        inputs,
+        kernel,
+        strides=self.strides,
+        padding=self.padding,
+        data_format=self.data_format,
+        dilation_rate=self.dilation_rate,
+    )
+
+  @tf.function(jit_compile=True)
+  def _jit_compiled_convolution_op(self, inputs, kernel):
+    return self.convolution_op(inputs, kernel)
+
   def call(self, inputs):
     if self.kernel_quantizer:
       quantized_kernel = self.kernel_quantizer_internal(self.kernel)
     else:
       quantized_kernel = self.kernel
 
-    outputs = tf.keras.backend.conv2d(
-        inputs,
-        quantized_kernel,
-        strides=self.strides,
-        padding=self.padding,
-        data_format=self.data_format,
-        dilation_rate=self.dilation_rate)
+    if self._mask is not None:
+      # Apply mask to kernel weights if one is provided.
+      quantized_kernel = quantized_kernel * self._mask
+
+    # Grouped convolutions are not fully supported on the CPU for compiled
+    # functions.
+    #
+    # This is a workaround taken from TF's core library. Remove when proper
+    # support is added.
+    # See definition of function "_jit_compiled_convolution_op" at
+    # cs/third_party/py/tf_keras/layers/convolutional/base_conv.py for more
+    # details.
+    if self.groups > 1:
+      outputs = self._jit_compiled_convolution_op(
+          inputs, tf.convert_to_tensor(quantized_kernel)
+      )
+    else:
+      outputs = self.convolution_op(inputs, quantized_kernel)
 
     if self.use_bias:
       if self.bias_quantizer:
@@ -364,7 +409,8 @@ def call(self, inputs):
         quantized_bias = self.bias
 
       outputs = tf.keras.backend.bias_add(
-          outputs, quantized_bias, data_format=self.data_format)
+          outputs, quantized_bias, data_format=self.data_format
+      )
 
     if self.activation is not None:
       return self.activation(outputs)
@@ -380,10 +426,19 @@ def get_config(self):
         ),
         "kernel_range": self.kernel_range,
         "bias_range": self.bias_range,
+        "mask": self._mask.tolist() if self._mask is not None else None,
     }
-    base_config = super(QConv2D, self).get_config()
+    base_config = super().get_config()
     return dict(list(base_config.items()) + list(config.items()))
 
+  @classmethod
+  def from_config(cls, config):
+    mask = config.get("mask")
+    if mask is not None:
+      mask = np.array(mask)
+    config["mask"] = mask
+    return cls(**config)
+
   def get_quantization_config(self):
     return {
         "kernel_quantizer":

tests/qconvolutional_test.py

@@ -308,5 +308,99 @@ def test_qconv2dtranspose():
       [2., 3., 4., 4., 3., 2.] ]).reshape((1,6,6,1)).astype(np.float16)
   assert_allclose(actual_output, expected_output, rtol=1e-4)
 
+
+def test_masked_qconv2d_creates_correct_parameters():
+  mask = mask = np.ones((5, 5), dtype=np.float32)
+  model = tf.keras.Sequential()
+  model.add(tf.keras.layers.Input(shape=(10, 10, 1)))
+  model.add(QConv2D(mask=mask, filters=1, kernel_size=(5, 5), use_bias=False))
+
+  # There should be no non-trainable params.
+  np.testing.assert_equal(len(model.non_trainable_weights), 0)
+
+  # Validate number of trainable params. This should be equal to one (5,5)
+  # kernel.
+  np.testing.assert_equal(len(model.trainable_weights), 1)
+  num_trainable_params = np.prod(model.trainable_weights[0].shape)
+  np.testing.assert_equal(num_trainable_params, 25)
+
+
+def test_qconv2d_masks_weights():
+  # Create an arbitrary mask.
+  mask = np.array(
+      [
+          [1.0, 0.0, 1.0, 0.0, 1.0],
+          [0.0, 0.0, 1.0, 0.0, 0.0],
+          [1.0, 0.0, 1.0, 0.0, 1.0],
+          [0.0, 0.0, 1.0, 0.0, 0.0],
+          [1.0, 0.0, 1.0, 0.0, 1.0],
+      ],
+      dtype=np.float32,
+  )
+  model = tf.keras.Sequential()
+  model.add(tf.keras.layers.Input(shape=(5, 5, 1)))
+  model.add(QConv2D(mask=mask, filters=1, kernel_size=(5, 5), use_bias=False))
+
+  # Set the weights to be all ones.
+  model.layers[0].set_weights([np.ones((5, 5, 1, 1), dtype=np.float32)])
+
+  # Run inference on a all ones input.
+  output = model.predict(np.ones((1, 5, 5, 1), dtype=np.float32))
+  # Output should just be summation of number of ones in the mask.
+  np.testing.assert_array_equal(
+      output, np.array([[[[11.0]]]], dtype=np.float32)
+  )
+
+
+def test_masked_qconv2d_load_restore_works():
+  model = tf.keras.Sequential()
+  model.add(tf.keras.layers.Input(shape=(10, 10, 1)))
+  model.add(
+      QConv2D(
+          mask=np.ones((5, 5), dtype=np.float32),
+          filters=1,
+          kernel_size=(5, 5),
+          use_bias=False,
+      )
+  )
+
+  with tempfile.TemporaryDirectory() as temp_dir:
+    model_path = os.path.join(temp_dir, 'model.keras')
+    # Can save the model.
+    model.save(model_path)
+
+    # Can load the model.
+    custom_objects = {
+        'QConv2D': QConv2D,
+    }
+    loaded_model = tf.keras.models.load_model(
+        model_path, custom_objects=custom_objects
+    )
+
+    np.testing.assert_array_equal(
+        model.layers[0].weights[0], loaded_model.layers[0].weights[0]
+    )
+
+
+def test_qconv2d_groups_works():
+  model = tf.keras.Sequential()
+  model.add(tf.keras.layers.Input(shape=(10, 10, 10)))
+  model.add(
+      QConv2D(
+          filters=6,
+          kernel_size=(1, 1),
+          use_bias=True,
+          groups=2,
+      )
+  )
+  # Validate number of trainable params.
+  np.testing.assert_equal(len(model.trainable_weights), 2)
+  num_trainable_params = np.prod(model.trainable_weights[0].shape) + np.prod(
+      model.trainable_weights[1].shape
+  )
+  expected_trainable_params = 36  # (5*3)*2 + 6
+  np.testing.assert_equal(num_trainable_params, expected_trainable_params)
+
+
 if __name__ == '__main__':
   pytest.main([__file__])