MLBEDSW-7408: MLCE: Crash when serialising model LSTM

 - Added checking and reporting of missing operator attributes when
reading and writing TFLite file
 - Added a TFLite semantic check to ensure that all required attribute
fields of builtin operators are read
 - Added some sanity checks for RESHAPE operators that run on the
Ethos-U
 - Stopped CPU operators from having their attributes modified

Change-Id: I05700681acdb09554f5945819717c08a9457295c
Signed-off-by: Tim Hall <tim.hall@arm.com>

1 files changed, 28 insertions, 16 deletions

diff --git a/ethosu/vela/tflite_writer.py b/ethosu/vela/tflite_writer.py
index 32982298..8d44774b 100644
--- a/ethosu/vela/tflite_writer.py
+++ b/ethosu/vela/tflite_writer.py
@@ -40,6 +40,7 @@ from .tflite import Tensor
 from .tflite_mapping import builtin_operator_inv_map
 from .tflite_mapping import BuiltinOperator
 from .tflite_mapping import datatype_inv_map
+from .tflite_mapping import optype_to_builtintype
 
 # the python flatbuffer interface is missing a method to add in file identifier. patching it in here:
 
@@ -310,25 +311,36 @@ class TFLiteSerialiser:
         custom_opt_offset = None
         if opt_serializer is not None:
             attrs = dict(op.attrs)
-            if "strides" in attrs:
-                attrs["stride_h"] = attrs["strides"][1]
-                attrs["stride_w"] = attrs["strides"][2]
-            if "ksize" in attrs:
-                attrs["filter_height"] = attrs["ksize"][1]
-                attrs["filter_width"] = attrs["ksize"][2]
-            if "dilation" in attrs:
-                attrs["dilation_h_factor"] = attrs["dilation"][1]
-                attrs["dilation_w_factor"] = attrs["dilation"][2]
-            if "channel_multiplier" in attrs:
-                attrs["depth_multiplier"] = attrs["channel_multiplier"]
-            if "container" in attrs:
-                attrs["container"] = builder.CreateString(attrs["container"])
-            if "shared_name" in attrs:
-                attrs["shared_name"] = builder.CreateString(attrs["shared_name"])
-            attrs["fused_activation_function"] = op.activation.op_type if op.activation is not None else None
+            if op.run_on_npu:
+                if "strides" in attrs:
+                    attrs["stride_h"] = attrs["strides"][1]
+                    attrs["stride_w"] = attrs["strides"][2]
+                if "ksize" in attrs:
+                    attrs["filter_height"] = attrs["ksize"][1]
+                    attrs["filter_width"] = attrs["ksize"][2]
+                if "dilation" in attrs:
+                    attrs["dilation_h_factor"] = attrs["dilation"][1]
+                    attrs["dilation_w_factor"] = attrs["dilation"][2]
+                if "channel_multiplier" in attrs:
+                    attrs["depth_multiplier"] = attrs["channel_multiplier"]
+                if "container" in attrs:
+                    attrs["container"] = builder.CreateString(attrs["container"])
+                if "shared_name" in attrs:
+                    attrs["shared_name"] = builder.CreateString(attrs["shared_name"])
+                attrs["fused_activation_function"] = op.activation.op_type if op.activation is not None else None
 
             builtin_opt_offset, custom_opt_offset = opt_serializer.serialize(builder, attrs)
 
+            # report any missing attributes that could not be written during serialize().
+            # operators that have been created internally (i.e. not created as part of reading an input network) may not
+            # have the write error attribute
+            attribute_write_error = attrs.get("attribute_write_error", [])
+            if len(attribute_write_error) != 0:
+                print(
+                    f"Warning: Could not write the following attributes to {optype_to_builtintype(op.type)}"
+                    f" '{op.name}' {opt_serializer.name} field: {', '.join(attribute_write_error)}"
+                )
+
         mutating_variable_inputs_offset = self.write_byte_vector([])
         Operator.OperatorStart(builder)
         Operator.OperatorAddOpcodeIndex(builder, op_idx)