Fix onnx ints (#19102)

Summary:
If JIT constant propagation doesn't work, we have to handle the ListConstructor in symbolic.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/19102

Reviewed By: zrphercule

Differential Revision: D14875588

Pulled By: houseroad

fbshipit-source-id: d25c847d224d2d32db50aae1751100080e115022

1 files changed, 24 insertions, 13 deletions

diff --git a/torch/onnx/symbolic.py b/torch/onnx/symbolic.py
index 27ba60ae69..bb656bda93 100644
--- a/torch/onnx/symbolic.py
+++ b/torch/onnx/symbolic.py
@@ -69,19 +69,30 @@ def _parse_arg(value, desc):
         return value
     if desc == 'v' or not _is_value(value):
         return value
-    if value.node().kind() != 'onnx::Constant':
-        raise RuntimeError("ONNX symbolic expected a constant value in the trace")
-    tval = value.node()['value']
-    if desc == 'i':
-        return int(tval)
-    elif desc == 'f':
-        return float(tval)
-    elif desc == 't':
-        return tval
-    elif desc == 'is':
-        return [int(v) for v in tval]
-    else:
-        raise RuntimeError("Casting constants to `{}` is not implemented".format(desc))
+    if value.node().kind() == 'onnx::Constant':
+        tval = value.node()['value']
+        if desc == 'i':
+            return int(tval)
+        elif desc == 'f':
+            return float(tval)
+        elif desc == 't':
+            return tval
+        elif desc == 'is':
+            return [int(v) for v in tval]
+        else:
+            raise RuntimeError("ONNX symbolic doesn't know to interpret Constant node")
+    elif value.node().kind() == 'prim::ListConstruct':
+        if desc == 'is':
+            for v in value.node().inputs():
+                if v.node().kind() != 'onnx::Constant':
+                    raise RuntimeError("Failed to export an ONNX attribute, "
+                                       "since it's not constant, please try to make "
+                                       "things (e.g., kernel size) static if possible")
+            return [int(v.node()['value']) for v in value.node().inputs()]
+        else:
+            raise RuntimeError("ONNX symbolic doesn't know to interpret ListConstruct node")
+
+    raise RuntimeError("Unexpected node type: {}".format(value.node().kind()))
 
 
 def _maybe_get_const(value, desc):