[Relay][Frontend][ONNX] Allow condition in if op to be an array.

python/tvm/relay/frontend/onnx.py

@@ -2266,6 +2266,9 @@ class If(OnnxOpConverter):
     @classmethod
     def _impl_v1(cls, inputs, attr, params):
         cond = inputs[0]
+        # Convert array to bool if needed.
+        if len(infer_shape(cond)) > 0:
+            cond = _op.take(cond, _expr.const(0, dtype="int64"))
         then_branch = attr.get("then_branch", None)
         else_branch = attr.get("else_branch", None)
         assert then_branch is not None and else_branch is not None

tests/python/frontend/onnx/test_forward.py

@@ -3969,8 +3969,7 @@ def test_loop():
     verify_count_loop()
 
 
-@tvm.testing.uses_gpu
-def test_if():
+def verify_if(cond_array):
     # Given a bool scalar input cond.
     # return constant tensor x if cond is True, otherwise return constant tensor y.
     then_out = onnx.helper.make_tensor_value_info("then_out", onnx.TensorProto.FLOAT, [5])
@@ -4007,7 +4006,10 @@ def test_if():
     )
 
     if_model = onnx.helper.make_model(if_graph)
-    cond = np.array(1).astype("bool")
+    if cond_array:
+        cond = np.array([1]).astype("bool")
+    else:
+        cond = np.array(1).astype("bool")
     correct_out = x if cond else y
 
     for target, ctx in tvm.testing.enabled_targets():
@@ -4016,6 +4018,13 @@ def test_if():
             tvm.testing.assert_allclose(correct_out[i], tvm_out[i], rtol=1e-05, atol=1e-05)
 
 
+@tvm.testing.uses_gpu
+def test_if():
+    # Confirm that if works with cond as an array or scalar.
+    verify_if(cond_array=False)
+    verify_if(cond_array=True)
+
+
 @tvm.testing.uses_gpu
 def test_size():
     def verify_size(indata):