[fx] Accept `func_visibility=` and return created func op. (#3054)

This is a partial landing of #3046 while waiting for an upstream change
for the rest of it.

python/torch_mlir/extras/fx_importer.py

@@ -302,7 +302,9 @@ def sparsity_encoding(shape: torch.Size, sparsity: SparsityMeta) -> str:
     if sparsity.layout is torch.sparse_coo:
         assert sparse_dim >= 2 and blocksize is None
         trail_dim = batch_dim + sparse_dim - 1
-        coords = ",".join(f"d{d}:singleton(nonunique,soa)" for d in range(batch_dim+1, trail_dim))
+        coords = ",".join(
+            f"d{d}:singleton(nonunique,soa)" for d in range(batch_dim + 1, trail_dim)
+        )
         sep = "," if sparse_dim > 2 else ""
         lvls = f"d{batch_dim}:compressed(nonunique),{coords}{sep}d{trail_dim}:singleton(soa)"
     elif sparsity.layout is torch.sparse_csr:
@@ -467,8 +469,12 @@ class FxImporter:
         return self._m.operation
 
     def import_program(
-        self, prog: torch.export.ExportedProgram, *, func_name: str = "main"
-    ):
+        self,
+        prog: torch.export.ExportedProgram,
+        *,
+        func_name: str = "main",
+        func_visibility: Optional[str] = None,
+    ) -> Operation:
         """Imports an ExportedProgram according to our chosen canonical representation.
 
         This mechanism is the fully general solution for handling an ExportedProgram
@@ -628,7 +634,9 @@ class FxImporter:
 
         # Create the function.
         with loc:
-            func_op = func_dialect.FuncOp(func_name, ftype, ip=self._m_ip)
+            func_op = func_dialect.FuncOp(
+                func_name, ftype, ip=self._m_ip, visibility=func_visibility
+            )
             entry_block = Block.create_at_start(func_op.body, ftype.inputs)
 
         node_importer = GraphNodeImporter(
@@ -668,10 +676,15 @@ class FxImporter:
         )
         node_importer.return_node_values(loc, user_outputs)
         self.symbol_table.insert(func_op)
+        return func_op
 
     def import_frozen_program(
-        self, prog: torch.export.ExportedProgram, func_name: str = "main"
-    ):
+        self,
+        prog: torch.export.ExportedProgram,
+        *,
+        func_name: str = "main",
+        func_visibility: Optional[str] = None,
+    ) -> Operation:
         """Imports a consolidated torch.export.ExportedProgram instance.
 
         If using the new torch.export path (vs a lower level precursor), then this is
@@ -750,17 +763,25 @@ class FxImporter:
                 node.replace_all_uses_with(replacement)
                 g.erase_node(node)
 
-        self.import_stateless_graph(g, func_name)
+        return self.import_stateless_graph(
+            g, func_name=func_name, func_visibility=func_visibility
+        )
 
-    def import_graph_module(self, gm: GraphModule):
+    def import_graph_module(self, gm: GraphModule) -> Operation:
         """Low-level import of a GraphModule assuming that it has been functionalized.
 
         TODO: This mechanism is deprecated by the `import_program` entry-point and
         it should be removed when no longer required for backwards compatibility.
         """
-        self.import_stateless_graph(gm.graph)
+        return self.import_stateless_graph(gm.graph)
 
-    def import_stateless_graph(self, g: Graph, func_name: str = "main"):
+    def import_stateless_graph(
+        self,
+        g: Graph,
+        *,
+        func_name: str = "main",
+        func_visibility: Optional[str] = None,
+    ) -> Operation:
         """Low-level import of a functionalized, assumed stateless Graph as a func.
 
         TODO: This mechanism is deprecated by the `import_program` entry-point and
@@ -775,6 +796,7 @@ class FxImporter:
                 func_name,
                 ftype,
                 ip=self._m_ip,
+                visibility=func_visibility,
             )
             entry_block = Block.create_at_start(func.body, ftype.inputs)
         node_importer = GraphNodeImporter(
@@ -785,6 +807,7 @@ class FxImporter:
         )
         node_importer.import_nodes(g.nodes)
         self.symbol_table.insert(func)
+        return func
 
     def _graph_to_function_meta(self, g: Graph) -> Tuple[FunctionType, Location]:
         """Extracts function metadata from the Graph.