message: Improve some CPU Conv2D error messages.
diff: @@ -141,15 +141,21 @@ struct LaunchConv2DOp<CPUDevice, T> {
  const std::vector<int64>& explicit_paddings, Tensor* output,
  TensorFormat data_format) {
  if (data_format != FORMAT_NHWC) {
  - ctx->SetStatus(
  - errors::Unimplemented("Generic conv implementation only supports "
  - "NHWC tensor format for now."));
  + ctx->SetStatus(errors::Unimplemented(
  + "The Conv2D op currently only supports the NHWC tensor format on the "
  + "CPU. The op was given the format: ",
  + ToString(data_format)));
  return;
  }
  const int64 in_depth = GetTensorDim(input, data_format, 'C');
  OP_REQUIRES(ctx, in_depth == filter.dim_size(2),
  - errors::Unimplemented("Generic conv implementation does not "
  - "support grouped convolutions for now."));
  + errors::Unimplemented(
  + "The Conv2D op currently does not support grouped "
  + "convolutions on the CPU. A grouped convolution was "
  + "attempted to be run because the input depth of ",
  + in_depth, " does not match the filter input depth of ",
  + filter.dim_size(2)));
  +
  for (int64 explicit_padding : explicit_paddings) {
  if (!FastBoundsCheck(explicit_padding, std::numeric_limits<int>::max())) {
  ctx->SetStatus(errors::InvalidArgument("filter too large"));
  