[quant][fix] Add bias once in conv_fused (#48593)

Summary:
Pull Request resolved: #48593

Previously _conv_forward will add self.bias to the result, so bias is added twice in qat ConvBn module
this PR added a bias argument to _conv_forward and _conv_forward is called with zero bias
in ConvBn module

fixes: #48514

Test Plan: Imported from OSS

Reviewed By: raghuramank100

Differential Revision: D25222215

fbshipit-source-id: 90c0ab79835b6d09622dcfec9de4139881a60746

test/quantization/test_qat_module.py

@@ -52,6 +52,7 @@ def __init__(self,
         self.register_buffer('num_batches_tracked', torch.tensor(0, dtype=torch.long))
         self.activation_post_process = self.qconfig.activation()
         self.weight_fake_quant = self.qconfig.weight()
+        self.zero_bias = torch.zeros(out_channels)
         if bias:
             self.bias = nn.Parameter(torch.Tensor(out_channels))
         else:
@@ -110,7 +111,7 @@ def _forward(self, input):
         running_std = torch.sqrt(self.running_var + self.eps)
         scale_factor = self.gamma / running_std
         scaled_weight = self.weight * scale_factor.reshape([-1, 1, 1, 1])
-        conv = self._conv_forward(input, self.weight_fake_quant(scaled_weight))
+        conv = self._conv_forward(input, self.weight_fake_quant(scaled_weight), self.zero_bias)
 
         if self.training and not self.freeze_bn:
             # recovering original conv to get original batch_mean and batch_var

torch/nn/intrinsic/qat/modules/conv_fused.py

@@ -43,6 +43,7 @@ def __init__(self,
         self.freeze_bn = freeze_bn if self.training else True
         self.bn = _BN_CLASS_MAP[dim](out_channels, eps, momentum, True, True)
         self.weight_fake_quant = self.qconfig.weight()
+        self.zero_bias = torch.zeros(out_channels)
         if bias:
             self.bias = Parameter(torch.Tensor(out_channels))
         else:
@@ -94,7 +95,7 @@ def _forward(self, input):
         bias_shape[1] = -1
         scaled_weight = self.weight_fake_quant(self.weight * scale_factor.reshape(weight_shape))
         # this does not include the conv bias
-        conv = self._conv_forward(input, scaled_weight)
+        conv = self._conv_forward(input, scaled_weight, self.zero_bias)
         conv_orig = conv / scale_factor.reshape(bias_shape)
         if self.bias is not None:
             conv_orig = conv_orig + self.bias.reshape(bias_shape)
@@ -402,7 +403,7 @@ def __init__(self, in_channels, out_channels, kernel_size, stride=1,
 
     def forward(self, input):
         return F.relu(
-            self._conv_forward(input, self.weight_fake_quant(self.weight)))
+            self._conv_forward(input, self.weight_fake_quant(self.weight), self.bias))
 
     @classmethod
     def from_float(cls, mod):

torch/nn/modules/conv.py

@@ -245,16 +245,16 @@ def __init__(
             in_channels, out_channels, kernel_size, stride, padding, dilation,
             False, _single(0), groups, bias, padding_mode)
 
-    def _conv_forward(self, input, weight):
+    def _conv_forward(self, input: Tensor, weight: Tensor, bias: Optional[Tensor]):
         if self.padding_mode != 'zeros':
             return F.conv1d(F.pad(input, self._reversed_padding_repeated_twice, mode=self.padding_mode),
-                            weight, self.bias, self.stride,
+                            weight, bias, self.stride,
                             _single(0), self.dilation, self.groups)
-        return F.conv1d(input, weight, self.bias, self.stride,
+        return F.conv1d(input, weight, bias, self.stride,
                         self.padding, self.dilation, self.groups)
 
     def forward(self, input: Tensor) -> Tensor:
-        return self._conv_forward(input, self.weight)
+        return self._conv_forward(input, self.weight, self.bias)
 
 
 class Conv2d(_ConvNd):
@@ -381,16 +381,16 @@ def __init__(
             in_channels, out_channels, kernel_size, stride, padding, dilation,
             False, _pair(0), groups, bias, padding_mode)
 
-    def _conv_forward(self, input, weight):
+    def _conv_forward(self, input: Tensor, weight: Tensor, bias: Optional[Tensor]):
         if self.padding_mode != 'zeros':
             return F.conv2d(F.pad(input, self._reversed_padding_repeated_twice, mode=self.padding_mode),
-                            weight, self.bias, self.stride,
+                            weight, bias, self.stride,
                             _pair(0), self.dilation, self.groups)
-        return F.conv2d(input, weight, self.bias, self.stride,
+        return F.conv2d(input, weight, bias, self.stride,
                         self.padding, self.dilation, self.groups)
 
     def forward(self, input: Tensor) -> Tensor:
-        return self._conv_forward(input, self.weight)
+        return self._conv_forward(input, self.weight, self.bias)
 
 class Conv3d(_ConvNd):
     __doc__ = r"""Applies a 3D convolution over an input signal composed of several input

torch/nn/qat/modules/conv.py

@@ -29,7 +29,7 @@ def __init__(self, in_channels, out_channels, kernel_size, stride=1,
         self.weight_fake_quant = qconfig.weight()
 
     def forward(self, input):
-        return self._conv_forward(input, self.weight_fake_quant(self.weight))
+        return self._conv_forward(input, self.weight_fake_quant(self.weight), self.bias)
 
     @classmethod
     def from_float(cls, mod):