Make convert to linear an export pass

Summary: Let's remove the reliance on export pass from convert to linear pass. This allows us. We only use exported program in one place to find the bias.

Differential Revision: D62266927

Author: mcr229

backends/xnnpack/passes/convert_to_linear.py

@@ -13,9 +13,9 @@
 from executorch.backends.transforms.addmm_mm_to_linear import (
     apply_addmm_mm_to_linear_transform,
 )
-from executorch.backends.xnnpack.passes.xnnpack_pass import XNNPACKPass
 from executorch.backends.xnnpack.utils.utils import is_param_node
 from executorch.exir.dialects._ops import ops as exir_ops
+from executorch.exir.pass_base import ExportPass
 
 from torch.fx.passes.infra.pass_base import PassResult
 from torch.fx.passes.utils.source_matcher_utils import (
@@ -27,7 +27,7 @@
 logger.setLevel(logging.WARNING)
 
 
-class ConvertToLinearPass(XNNPACKPass):
+class ConvertToLinearPass(ExportPass):
     linear_modules = [
         torch.nn.Linear,
         torch.nn.functional.linear,
@@ -71,28 +71,25 @@ def get_arg(node: torch.fx.Node, arg: str):
             map_ = {"input": 0, "weight": 1}
             return None if arg == "bias" else node.args[map_[arg]]
 
-    def find_bias_for_mm(self, src_partition: SourcePartition, weight: torch.fx.Node):
+    def find_bias_for_mm(self, src_partition: SourcePartition, mm_node: torch.fx.Node):
         """
         For linear decomposed with mm + add, find bias in src partition
         """
-        out_channels = get_shape(weight)[0]
-        bias = None
-
-        # Try to find bias node in all nodes
-        for node in src_partition.nodes:
-            if is_param_node(self.exported_program, node) and node != weight:
-                bias = node
-
-        if bias is not None:
-            assert get_shape(bias) == [
-                out_channels
-            ], f"Expected bias shape {[out_channels]} but got {get_shape(bias)}"
-        else:
-            assert exir_ops.edge.aten.add.Tensor not in [
-                node.target for node in src_partition.nodes
-            ], f"Expecting to find bias for Linear module: {src_partition} but could not find it"
 
-        return bias
+        mm_users = list(mm_node.users.keys())
+        if len(mm_users) != 1:
+            return None
+
+        add_node = mm_users[0]
+        if add_node.target != exir_ops.edge.aten.add.Tensor:
+            return None
+
+        for arg in add_node.all_input_nodes:
+            if arg != mm_node and arg in src_partition.input_nodes:
+                return arg
+
+        return None
+
 
     def create_linear(
         self,
@@ -119,7 +116,7 @@ def create_linear(
             src_partition.input_nodes + src_partition.params,  # bias can be in params
         )
         if linear_bias is None and node.target == exir_ops.edge.aten.mm.default:
-            linear_bias = self.find_bias_for_mm(src_partition, linear_weight)
+            linear_bias = self.find_bias_for_mm(src_partition, node)
 
         logger.debug(f"Found bias(?): {linear_bias} from node {node}")