[Relax][ONNX] Add Exp op (apache#28)

Add exp operation to ONNX front-end of Relax

---------

Co-authored-by: Valery Chernov <[email protected]>

python/tvm/relax/frontend/onnx/onnx_frontend.py

@@ -779,6 +779,32 @@ def _impl_v13(cls, bb, inputs, attr):
         return attach_span(relax.op.log(inputs[0]))
 
 
+class Exp(OnnxOpConverter):
+    """Converts an onnx Exp node into an equivalent Relax expression."""
+
+    @classmethod
+    def _check_type(cls, dtype, valid_types):
+        assert dtype in valid_types, "Types {} are supported only, but {} is given".format(
+            valid_types, dtype
+        )
+
+    @classmethod
+    def _impl_v1(cls, bb, inputs, attr):
+        data = inputs[0]
+        valid_types = ["float", "float32", "double", "float64", "float16"]
+        cls._check_type(data.checked_type.dtype, valid_types)
+
+        return relax.op.exp(data)
+
+    @classmethod
+    def _impl_v13(cls, bb, inputs, attr):
+        data = inputs[0]
+        valid_types = ["float", "float32", "double", "float64", "float16", "bfloat16"]
+        cls._check_type(data.checked_type.dtype, valid_types)
+
+        return relax.op.exp(data)
+
+
 class Less(OnnxOpConverter):
     """Converts an onnx Less node into an equivalent Relax expression."""
 
@@ -1705,6 +1731,7 @@ def _get_convert_map():
         "Min": Min,
         "Max": Max,
         "Log": Log,
+        "Exp": Exp,
         "Less": Less,
         "LessOrEqual": LessOrEqual,
         "LayerNormalization": LayerNormalization,

tests/python/relax/frontend/test_onnx_frontend.py

@@ -710,6 +710,10 @@ def test_log():
     verify_unary("Log", [32, 16])
 
 
+def test_exp():
+    verify_unary("Exp", [32, 16])
+
+
 def test_instance_norm():
     verify_ternary(
         "InstanceNormalization", [1, 3, 32, 32], [3], [3], [1, 3, 32, 32], attrs={"epsilon": 1e-12}