[ONNX] Add onnx::Gelu support for version 20 (pytorch#128773)

Fixes pytorch#128772
Pull Request resolved: pytorch#128773
Approved by: https://github.com/justinchuby

Author: YibinLiu666

test/onnx/test_utility_funs.py

@@ -1358,6 +1358,8 @@ def forward(self, input, other):
         iter = graph.nodes()
         self.assertEqual(next(iter).kind(), "custom_namespace::custom_op")
 
+    # gelu is exported as onnx::Gelu for opset >= 20
+    @skipIfUnsupportedMaxOpsetVersion(19)
     def test_custom_opsets_gelu(self):
         self.addCleanup(torch.onnx.unregister_custom_op_symbolic, "::gelu", 9)
 
@@ -1382,6 +1384,8 @@ def gelu(g, self, approximate):
         self.assertEqual(graph.opset_import[1].domain, "com.microsoft")
         self.assertEqual(graph.opset_import[1].version, 1)
 
+    # gelu is exported as onnx::Gelu for opset >= 20
+    @skipIfUnsupportedMaxOpsetVersion(19)
     def test_register_aten_custom_op_symbolic(self):
         self.addCleanup(torch.onnx.unregister_custom_op_symbolic, "aten::gelu", 9)
 

torch/onnx/symbolic_opset20.py

@@ -32,7 +32,7 @@
 # EDITING THIS FILE? READ THIS FIRST!
 # see Note [Edit Symbolic Files] in symbolic_helper.py
 
-__all__ = ["_grid_sampler", "_affine_grid_generator"]
+__all__ = ["_grid_sampler", "_affine_grid_generator", "gelu"]
 
 
 def convert_grid_sample_mode(mode_s):
@@ -84,3 +84,10 @@ def _affine_grid_generator(
         size,
         align_corners_i=int(align_corners),
     )
+
+
+@_onnx_symbolic("aten::gelu")
+@symbolic_helper.parse_args("v", "s")
+@_beartype.beartype
+def gelu(g: jit_utils.GraphContext, self: _C.Value, approximate: str = "none"):
+    return g.op("Gelu", self, approximate_s=approximate)