[ConvertBipolarMatMulToXnorPopcount] support bipolar -> binary inp

src/finn/transformation/bipolar_to_xnor.py

@@ -27,6 +27,7 @@
 # OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 import numpy as np
+import warnings
 from onnx import TensorProto
 from onnx import helper as oh
 
@@ -66,26 +67,40 @@ class ConvertBipolarMatMulToXnorPopcount(Transformation):
 
                     mt_chain = model.find_upstream(mm_input, find_prod_mt)
                     if len(mt_chain) == 0:
-                        raise Exception(
-                            """Could not find upstream bipolar
-                                            MultiThreshold"""
-                        )
-                    graph_modified = True
-                    mt = mt_chain[-1]
-                    mt_inst = getCustomOp(mt)
-                    # ensure old scale/bias were correct for BIPOLAR
-                    scale_ok = mt_inst.get_nodeattr("out_scale") == 2.0
-                    bias_ok = mt_inst.get_nodeattr("out_bias") == -1.0
-                    assert (
-                        scale_ok and bias_ok
-                    ), """Unexpected scale/bias
-                    attributes for BIPOLAR MultiThreshold node."""
-                    # start conversion, set MT output to binary
-                    # (this is what XnorPopcountMatMul expects)
-                    mt_inst.set_nodeattr("out_dtype", "BINARY")
-                    mt_inst.set_nodeattr("out_scale", 1.0)
-                    mt_inst.set_nodeattr("out_bias", 0.0)
-                    model.set_tensor_datatype(mm_input, DataType.BINARY)
+                        if mm_input == graph.input[0].name:
+                            # change input datatype to BINARY
+                            model.set_tensor_datatype(mm_input, DataType.BINARY)
+                            graph_modified = True
+                            warnings.warn(
+                                """IMPORTANT: Changing graph input DataType
+                            to BINARY instead of BIPOLAR. Ensure this is respected
+                            when checking for correctness.
+                            """
+                            )
+                        else:
+                            raise Exception(
+                                """Could not find upstream bipolar
+                                   MultiThreshold, and the MatMul is not the
+                                   first node on graph input. Unable to convert
+                                   input tensor from BIPOLAR to BINARY."""
+                            )
+                    else:
+                        graph_modified = True
+                        mt = mt_chain[-1]
+                        mt_inst = getCustomOp(mt)
+                        # ensure old scale/bias were correct for BIPOLAR
+                        scale_ok = mt_inst.get_nodeattr("out_scale") == 2.0
+                        bias_ok = mt_inst.get_nodeattr("out_bias") == -1.0
+                        assert (
+                            scale_ok and bias_ok
+                        ), """Unexpected scale/bias
+                        attributes for BIPOLAR MultiThreshold node."""
+                        # start conversion, set MT output to binary
+                        # (this is what XnorPopcountMatMul expects)
+                        mt_inst.set_nodeattr("out_dtype", "BINARY")
+                        mt_inst.set_nodeattr("out_scale", 1.0)
+                        mt_inst.set_nodeattr("out_bias", 0.0)
+                        model.set_tensor_datatype(mm_input, DataType.BINARY)
                     # change node type and domain
                     n.op_type = "XnorPopcountMatMul"
                     n.domain = "finn"