[ETHOSN] Apply FoldConstant before NPU partitioning (#13848)

Introduced FoldConstant before NPU partitioning.
Added a qnn.add test where both inputs are constants.
Updated the number of operators remaining in the host code
for ssd_mobilenet_v1 as the FoldConstant reduces the number
of operators.

python/tvm/relay/op/contrib/ethosn.py

@@ -129,6 +129,7 @@ def partition_for_ethosn(mod, params=None, **opts):
 
     passes = [
         transform.InferType(),
+        transform.FoldConstant(fold_qnn=True),
         transform.MergeComposite(pattern_table()),
         transform.AnnotateTarget("ethos-n"),
         transform.MergeCompilerRegions(),

tests/python/contrib/test_ethosn/test_addition.py

@@ -41,20 +41,28 @@ def _get_model(
 ):
     """Return a model and any parameters it may have"""
 
-    iinfo = np.iinfo(dtype)
-    data_min = iinfo.min
-    data_max = iinfo.max
+    def create_or_assign_constant(shape, dtype, default_data):
+        """Creates new numpy array or assigns default_data if available."""
+
+        iinfo = np.iinfo(dtype)
+        data_min = iinfo.min
+        data_max = iinfo.max
+
+        nparray = None
+        if default_data:
+            nparray = np.array(default_data, dtype=dtype).reshape(shape)
+        else:
+            nparray = np.random.randint(data_min, data_max + 1, size=shape, dtype=dtype)
+
+        return relay.const(nparray, dtype=dtype)
 
     if lhs_is_constant:
-        a_data = np.array(constant_data, dtype=dtype).reshape(lhs_shape)
-        a = relay.const(a_data, dtype=dtype)
+        a = create_or_assign_constant(lhs_shape, dtype, constant_data)
     else:
         a = relay.var("a", shape=lhs_shape, dtype=dtype)
 
     if rhs_is_constant:
-        b_data = np.array(constant_data, dtype=dtype).reshape(rhs_shape)
-        np.random.randint(data_min, data_max + 1, size=rhs_shape, dtype=dtype)
-        b = relay.const(b_data, dtype=dtype)
+        b = create_or_assign_constant(rhs_shape, dtype, constant_data)
     else:
         b = relay.var("b", shape=rhs_shape, dtype=dtype)
 
@@ -125,6 +133,46 @@ def test_addition(dtype, shape):
     tei.verify(outputs, dtype, 1)
 
 
+@requires_ethosn
+@pytest.mark.parametrize("dtype", ["uint8", "int8"])
+@pytest.mark.parametrize(
+    "lhs_shape,lhs_is_constant,rhs_shape,rhs_is_constant",
+    [
+        ((1, 4, 4, 8), True, (1, 1, 1, 8), True),
+        ((4,), True, (1, 16, 12, 4), True),
+        ((1, 1, 1, 8), True, (1, 4, 4, 8), True),
+        ((1, 16, 12, 4), True, (4,), True),
+    ],
+)
+def test_addition_both_inputs_constants(
+    dtype, lhs_shape, lhs_is_constant, rhs_shape, rhs_is_constant
+):
+    """Check if addition is simplified when both inputs are constants."""
+    np.random.seed(0)
+
+    lhs_zp, lhs_sc, rhs_zp, rhs_sc, out_zp, out_sc = _get_addition_qnn_params(dtype)
+
+    model = _get_model(
+        lhs_shape,
+        rhs_shape,
+        lhs_zp,
+        lhs_sc,
+        rhs_zp,
+        rhs_sc,
+        out_zp,
+        out_sc,
+        dtype,
+        lhs_is_constant=lhs_is_constant,
+        rhs_is_constant=rhs_is_constant,
+    )
+    from tvm.relay.op.contrib import partition_for_ethosn  # pylint: disable=import-outside-toplevel
+
+    mod = tei.make_module(model, {})
+    assert "qnn.add" in mod.astext(False)
+    mod = partition_for_ethosn(mod, {})
+    assert "qnn.add" not in mod.astext(False)
+
+
 @requires_ethosn
 @pytest.mark.parametrize("dtype", ["uint8", "int8"])
 @pytest.mark.parametrize(
@@ -145,9 +193,6 @@ def test_addition_to_depthwise(dtype, lhs_shape, lhs_is_constant, rhs_shape, rhs
     data_max = iinfo.max
     lhs_zp, lhs_sc, rhs_zp, rhs_sc, out_zp, out_sc = _get_addition_qnn_params(dtype)
 
-    constant_shape = lhs_shape if lhs_is_constant else rhs_shape
-    constant_data = np.random.randint(data_min, data_max + 1, size=constant_shape, dtype=dtype)
-
     model = _get_model(
         lhs_shape,
         rhs_shape,
@@ -160,7 +205,6 @@ def test_addition_to_depthwise(dtype, lhs_shape, lhs_is_constant, rhs_shape, rhs
         dtype,
         lhs_is_constant=lhs_is_constant,
         rhs_is_constant=rhs_is_constant,
-        constant_data=constant_data,
     )
     input_shape = rhs_shape if lhs_is_constant else lhs_shape
     input_name = "b" if lhs_is_constant else "a"

tests/python/contrib/test_ethosn/test_networks.py

@@ -218,6 +218,6 @@ def test_ssd_mobilenet_v1():
         input_dict={"normalized_input_image_tensor": (1, 300, 300, 3)},
         compile_hash=_compile_hash,
         output_count=4,
-        host_ops=26,
+        host_ops=14,
         npu_partitions=1,
     )