[Relay/TOPI][Op] Add erf intrinsic and op (#3702)

* add more ops

* stop vectorization for erf

* x

* cleanup

* fix

* add whitelist for vectorizable intrin

* add tf converter

* fix dense

* fix

* add missing intrin

* fix mxnet frontend

* fix nvptx

include/tvm/expr_operator.h

@@ -512,6 +512,7 @@ TVM_DLL Expr trunc(Expr x);
   }                                                                     \
 
 TVM_DECLARE_INTRIN_UNARY(exp);
+TVM_DECLARE_INTRIN_UNARY(erf);
 TVM_DECLARE_INTRIN_UNARY(tanh);
 TVM_DECLARE_INTRIN_UNARY(sigmoid);
 TVM_DECLARE_INTRIN_UNARY(sqrt);

include/tvm/ir.h

@@ -556,6 +556,9 @@ class Call : public ExprNode {
          name == intrin_name);
   }
 
+  /*! \return Whether call node can be vectorized. */
+  bool is_vectorizable() const;
+
   static constexpr const char* _type_key = "Call";
   TVM_DECLARE_NODE_TYPE_INFO(Call, ExprNode);
 
@@ -571,6 +574,9 @@ class Call : public ExprNode {
   static constexpr const char* likely = "likely";
   static constexpr const char* glsl_texture_store = "glsl_texture_store";
   static constexpr const char* prefetch = "prefetch";
+
+  /*! \brief Vectorizable intrinsic list. */
+  static const char* vectorizable_intrinsics[];
 };
 
 /*!

python/tvm/intrin.py

@@ -211,6 +211,22 @@ def exp(x):
     return call_pure_intrin(x.dtype, "exp", x)
 
 
+def erf(x):
+    """Take gauss error function of the input x.
+
+    Parameters
+    ----------
+    x : Expr
+        Input argument.
+
+    Returns
+    -------
+    y : Expr
+        The result.
+    """
+    return call_pure_intrin(x.dtype, "erf", x)
+
+
 def tanh(x):
     """Take hyperbolic tanh of input x.
 

python/tvm/relay/backend/interpreter.py

@@ -170,8 +170,8 @@ class Executor(object):
             return args
 
         if kwargs and not isinstance(expr, Function):
-            raise Exception("can only supply keyword parameters for a \
-                             relay.Function, found {0}".format(expr))
+            raise Exception("can only supply keyword parameters for a "
+                            "relay.Function, found {0}".format(expr))
 
         params = expr.params
         param_names = [p.name_hint for p in params]
@@ -182,16 +182,16 @@ class Executor(object):
             if i < num_of_args:
                 if kwargs.get(name):
                     raise Exception(
-                        "duplicate argument supplied in \
-                         both positional args (at position: {0}), \
-                         and keyword argument (with name: {1})".format(i, name))
+                        "duplicate argument supplied in "
+                        "both positional args (at position: {0}), "
+                        "and keyword argument (with name: {1})".format(i, name))
             else:
                 cargs.append(kwargs[name])
 
         if len(cargs) != len(params):
             raise Exception(
-                "insufficient arguments, expected" \
-                " {0}, provided {1}".format(len(cargs), len(params)))
+                "insufficient arguments, expected "
+                "{0}, provided {1}".format(len(cargs), len(params)))
 
         return tuple(cargs)
 

python/tvm/relay/frontend/common.py

@@ -124,7 +124,16 @@ class StrAttrsDict(object):
         """
         if key in self.attrs:
             tshape = self.attrs[key]
-            return tuple(int(x.strip()) for x in tshape.strip('()[]').split(',') if x)
+            ret = []
+            for x in tshape.strip('()[]').split(','):
+                x = x.strip()
+                if not x:
+                    continue
+                if x == "None":
+                    ret.append(None)
+                else:
+                    ret.append(int(x))
+            return tuple(ret)
         if isinstance(default, RequiredAttr):
             raise AttributeError("Required attribute {} not found.".format(key))
         return default

python/tvm/relay/frontend/mxnet.py

@@ -55,10 +55,17 @@ def _mx_fully_connected(inputs, attrs):
     use_flatten = attrs.get_bool("flatten", True)
     if has_flatten and use_flatten:
         inputs[0] = _op.nn.batch_flatten(inputs[0])
+    data_shape = _infer_type(inputs[0]).checked_type.shape
+    if len(data_shape) > 2:
+        inputs[0] = _op.reverse_reshape(inputs[0], [-1, 0])
     res = _op.nn.dense(inputs[0], inputs[1], units=units)
     if use_bias:
         assert len(inputs) == 3
         res = _op.nn.bias_add(res, inputs[2], axis=-1)
+    if len(data_shape) > 2:
+        new_shape = data_shape[:-1]
+        new_shape.append(units)
+        res = _op.reshape(res, new_shape)
     return res
 
 
@@ -241,8 +248,8 @@ def _mx_layer_norm(inputs, attrs):
 
 def _mx_slice(inputs, attrs):
     new_attrs = {}
-    begin = attrs.get_int_tuple('begin', None)
-    end = attrs.get_int_tuple('end', None)
+    begin = list(attrs.get_int_tuple('begin', None))
+    end = list(attrs.get_int_tuple('end', None))
     stride = attrs.get_int_tuple('step', None)
     if begin is None:
         raise tvm.error.OpAttributeRequired(
@@ -251,11 +258,12 @@ def _mx_slice(inputs, attrs):
         raise tvm.error.OpAttributeRequired(
             'Attribute "end" not found in operator Slice.')
     if None in begin:
-        raise tvm.error.OpAttributeInvalid(
-            'Value None in attribute "begin" of operator Slice is not valid.')
-    if None in end:
-        raise tvm.error.OpAttributeInvalid(
-            'Value None in attribute "end" of operator Slice is not valid.')
+        data_shape = _infer_type(inputs[0]).checked_type.shape
+        for i, beg in enumerate(begin):
+            if beg is None:
+                assert end[i] is None
+                begin[i] = 0
+                end[i] = data_shape[i]
     new_attrs = {'begin': begin, 'end': end}
     if stride is not None:
         new_attrs['strides'] = stride
@@ -497,7 +505,8 @@ def _mx_arange(inputs, attrs):
             'Attribute "repeat" is not supported in operator arange.')
     new_attrs = {}
     new_attrs["start"] = _expr.const(attrs.get_float("start", 0.0))
-    new_attrs["stop"] = _expr.const(attrs.get_float("stop"))
+    stop = attrs.get_str("stop", "None")
+    new_attrs["stop"] = None if stop == "None" else _expr.const(float(stop))
     new_attrs["step"] = _expr.const(attrs.get_float("step", 1.0))
     new_attrs["dtype"] = attrs.get_str("dtype", "float32")
     return _op.arange(**new_attrs)
@@ -910,6 +919,7 @@ def _mx_one_hot(inputs, attrs):
 _identity_list = [
     "log",
     "exp",
+    "erf",
     "sqrt",
     "floor",
     "ceil",

python/tvm/relay/frontend/tensorflow.py

@@ -1261,6 +1261,7 @@ _convert_map = {
     'DepthToSpace'                      : _depth_to_space(),
     'Equal'                             : _broadcast('equal'),
     'Elu'                               : _elu(),
+    'Erf'                               : AttrCvt('erf'),
     'Exp'                               : AttrCvt('exp'),
     'ExpandDims'                        : _expand_dims(),
     'Fill'                              : _fill(),

python/tvm/relay/op/_tensor.py

@@ -30,6 +30,7 @@ register_schedule("log1p", schedule_broadcast)
 register_schedule("cos", schedule_broadcast)
 register_schedule("sin", schedule_broadcast)
 register_schedule("exp", schedule_broadcast)
+register_schedule("erf", schedule_broadcast)
 register_schedule("sqrt", schedule_broadcast)
 register_schedule("rsqrt", schedule_broadcast)
 register_schedule("sigmoid", schedule_broadcast)

python/tvm/relay/op/tensor.py

@@ -92,6 +92,22 @@ def exp(data):
     return _make.exp(data)
 
 
+def erf(data):
+    """Compute elementwise error function of data.
+
+    Parameters
+    ----------
+    data : relay.Expr
+        The input data
+
+    Returns
+    -------
+    result : relay.Expr
+        The computed result.
+    """
+    return _make.erf(data)
+
+
 def sqrt(data):
     """Compute elementwise sqrt of data.
 

src/codegen/intrin_rule.cc

@@ -31,6 +31,9 @@ namespace intrin {
 TVM_REGISTER_GLOBAL("tvm.intrin.rule.default.exp")
 .set_body(DispatchExtern<FloatSuffix>);
 
+TVM_REGISTER_GLOBAL("tvm.intrin.rule.default.erf")
+.set_body(DispatchExtern<FloatSuffix>);
+
 TVM_REGISTER_GLOBAL("tvm.intrin.rule.default.log")
 .set_body(DispatchExtern<FloatSuffix>);
 

src/codegen/intrin_rule_cuda.cc

@@ -92,6 +92,9 @@ TVM_REGISTER_GLOBAL("tvm.intrin.rule.cuda.round")
 TVM_REGISTER_GLOBAL("tvm.intrin.rule.cuda.exp")
 .set_body(DispatchExtern<CUDAFastMath>);
 
+TVM_REGISTER_GLOBAL("tvm.intrin.rule.cuda.erf")
+.set_body(DispatchExtern<CUDAMath>);
+
 TVM_REGISTER_GLOBAL("tvm.intrin.rule.cuda.log")
 .set_body(DispatchExtern<CUDAFastMath>);
 

src/codegen/llvm/intrin_rule_nvptx.cc

@@ -64,6 +64,9 @@ TVM_REGISTER_GLOBAL("tvm.intrin.rule.nvptx.fabs")
 TVM_REGISTER_GLOBAL("tvm.intrin.rule.nvptx.exp")
 .set_body(DispatchExternLibDevice);
 
+TVM_REGISTER_GLOBAL("tvm.intrin.rule.nvptx.erf")
+.set_body(DispatchExternLibDevice);
+
 TVM_REGISTER_GLOBAL("tvm.intrin.rule.nvptx.fma")
 .set_body(DispatchExternLibDevice);
 

src/lang/ir.cc

@@ -176,6 +176,22 @@ Expr Let::make(Var var, Expr value, Expr body) {
   return Expr(node);
 }
 
+const char* Call::vectorizable_intrinsics[] = {
+    "floor", "ceil", "sign", "trunc", "fabs", "round", "exp", "tanh", "sqrt",
+    "log", "sin", "cos", "pow", ir::Call::shift_left, ir::Call::shift_right,
+    ir::Call::likely, ir::Call::popcount
+};
+
+bool Call::is_vectorizable() const {
+  size_t cnt = sizeof(Call::vectorizable_intrinsics) / sizeof(char*);
+  for (size_t i = 0; i < cnt; ++i) {
+    if (name == Call::vectorizable_intrinsics[i]) {
+      return true;
+    }
+  }
+  return false;
+}
+
 Expr Call::make(DataType type,
                 std::string name,
                 Array<Expr> args,

src/pass/vectorize_loop.cc

@@ -268,16 +268,34 @@ class Vectorizer : public IRMutator {
     if (op->name == intrinsic::tvm_if_then_else) {
       return MutateIfThenElseExpr_(op, e);
     }
-    int lane = 0;
-    Array<Expr> new_args = MutateArray(op->args, &lane);
-
-    // normal code path.
-    if (op->args.same_as(new_args)) {
-      return e;
+    if (!op->is_vectorizable()) {
+      // Cannot vectorize this op
+      Array<Expr> new_args;
+      for (auto arg : op->args) {
+        auto new_arg = this->Mutate(arg);
+        if (new_arg.type().is_vector()) {
+          need_scalarize_ = true;
+          return e;
+        }
+        new_args.push_back(new_arg);
+      }
+      if (op->args.same_as(new_args)) {
+        return e;
+      } else {
+        return Call::make(
+            op->type, op->name, new_args, op->call_type, op->func, op->value_index);
+      }
     } else {
-      return Call::make(
-          op->type.with_lanes(lane), op->name, new_args,
-          op->call_type, op->func, op->value_index);
+      int lane = 0;
+      Array<Expr> new_args = MutateArray(op->args, &lane);
+      // normal code path.
+      if (op->args.same_as(new_args)) {
+        return e;
+      } else {
+        return Call::make(
+            op->type.with_lanes(lane), op->name, new_args,
+            op->call_type, op->func, op->value_index);
+      }
     }
   }
   // Load

src/relay/op/tensor/unary.cc

@@ -85,6 +85,18 @@ RELAY_REGISTER_UNARY_OP("exp")
 .set_support_level(1)
 .set_attr<FTVMCompute>("FTVMCompute", RELAY_UNARY_COMPUTE(topi::exp));
 
+
+RELAY_REGISTER_UNARY_OP("erf")
+.describe(R"code(Returns the error function value for input array, computed element-wise.
+
+.. math::
+   \erf(x)
+
+)code" TVM_ADD_FILELINE)
+.set_support_level(1)
+.set_attr<FTVMCompute>("FTVMCompute", RELAY_UNARY_COMPUTE(topi::erf));
+
+
 RELAY_REGISTER_UNARY_OP("sqrt")
 .describe(R"code(Returns the sqrt input array, computed element-wise.
 

tests/python/frontend/tensorflow/test_forward.py

@@ -1844,6 +1844,14 @@ def test_forward_zeros_like():
         _test_forward_zeros_like((2, 3, 11), "float32")
         _test_forward_zeros_like((2, 3, 11), "float64")
 
+def test_forward_erf():
+    ishape = (1, 3, 10, 10)
+    inp_array = np.random.uniform(-5, 5, size=ishape).astype(np.float32)
+    with tf.Graph().as_default():
+        in1 = tf.placeholder(shape=inp_array.shape, dtype=inp_array.dtype)
+        tf.math.erf(in1)
+        compare_tf_with_tvm(inp_array, 'Placeholder:0', 'Erf:0')
+
 def _test_forward_reverse_v2(in_shape, axis, dtype):
     np_data = np.random.uniform(-10, 10, size=in_shape).astype(dtype)
     tf.reset_default_graph()
@@ -2244,6 +2252,7 @@ if __name__ == '__main__':
     test_forward_log_softmax()
     test_forward_bias_add()
     test_forward_zeros_like()
+    test_forward_erf()
 
     # Reductions
     test_forward_argminmax()

tests/python/relay/test_op_level1.py

@@ -16,6 +16,7 @@
 # under the License.
 import numpy as np
 import tvm
+import scipy
 from tvm import relay
 from tvm.relay import transform
 from tvm.relay.testing import ctx_list
@@ -67,6 +68,7 @@ def test_unary_op():
 
     for opfunc, ref in [(tvm.relay.log, np.log),
                         (tvm.relay.exp, np.exp),
+                        (tvm.relay.erf, scipy.special.erf),
                         (tvm.relay.sqrt, np.sqrt),
                         (tvm.relay.rsqrt, rsqrt),
                         (tvm.relay.sigmoid, sigmoid),

topi/include/topi/elemwise.h

@@ -46,6 +46,7 @@ using namespace tvm;
   }
 
 TOPI_DECLARE_UNARY_OP(exp);
+TOPI_DECLARE_UNARY_OP(erf);
 TOPI_DECLARE_UNARY_OP(sigmoid);
 TOPI_DECLARE_UNARY_OP(sqrt);
 TOPI_DECLARE_UNARY_OP(log);

topi/python/topi/math.py

@@ -74,6 +74,23 @@ def exp(x):
     return tvm.compute(x.shape, lambda *i: tvm.exp(x(*i)))
 
 
+@tvm.tag_scope(tag=tag.ELEMWISE)
+def erf(x):
+    """Take gauss error function of input x.
+
+    Parameters
+    ----------
+    x : tvm.Tensor
+        Input argument.
+
+    Returns
+    -------
+    y : tvm.Tensor
+        The result.
+    """
+    return tvm.compute(x.shape, lambda *i: tvm.erf(x(*i)))
+
+
 @tvm.tag_scope(tag=tag.ELEMWISE)
 def tanh(x):
     """Take hyperbolic tanh of input x.

topi/python/topi/x86/dense.py

@@ -28,12 +28,19 @@ from ..util import traverse_inline, get_const_tuple
 
 @autotvm.register_topi_compute(nn.dense, "cpu", "direct")
 def _declaration_dense(cfg, data, weight, bias=None, out_dtype=None):
-    batch, _ = get_const_tuple(data.shape)
+    target = tvm.target.current_target()
+    if "cblas" in target.libs:
+        C = cblas.matmul(data, weight, False, True)
+        if bias is not None:
+            C = tvm.compute(C.shape, lambda i, j: C[i, j] + bias[j].astype(out_dtype),
+                            tag=tag.BROADCAST)
+        return C
 
+    M, _ = get_const_tuple(data.shape)
     # For small batch sizes, don't pack weight into cache-friendly layout
     # because of overhead in packing and limited reuse from batch dimension
     # TODO(icemelon9): use a more systematic way to determine which schedule to use
-    if batch <= 16:
+    if M <= 16:
         return _declaration_dense_nopack(cfg, data, weight, bias, out_dtype)
     return _declaration_dense_pack(cfg, data, weight, bias, out_dtype)
 
@@ -41,35 +48,31 @@ def _declaration_dense(cfg, data, weight, bias=None, out_dtype=None):
 # Declare dense compute with packing weight into cache-friendly layout
 @autotvm.register_topi_compute(nn.dense, "cpu", "direct_pack")
 def _declaration_dense_pack(cfg, data, weight, bias=None, out_dtype=None):
-    target = tvm.target.current_target()
-    if "cblas" in target.libs:
-        C = cblas.matmul(data, weight, False, True)
-    else:
-        if out_dtype is None:
-            out_dtype = data.dtype
-        batch, in_dim = get_const_tuple(data.shape)
-        out_dim, _ = get_const_tuple(weight.shape)
-        # create tuning space
-        cfg.define_split("tile_y", batch, num_outputs=3)
-        cfg.define_split("tile_x", out_dim, num_outputs=3)
-        cfg.define_split("tile_k", in_dim, num_outputs=2)
-        if cfg.is_fallback:
-            _default_dense_pack_config(cfg, batch, out_dim, in_dim)
+    if out_dtype is None:
+        out_dtype = data.dtype
+    M, K = get_const_tuple(data.shape) # batch, in_dim
+    N, _ = get_const_tuple(weight.shape) # out_dim
+    # create tuning space
+    cfg.define_split("tile_y", M, num_outputs=3)
+    cfg.define_split("tile_x", N, num_outputs=3)
+    cfg.define_split("tile_k", K, num_outputs=2)
+    if cfg.is_fallback:
+        _default_dense_pack_config(cfg, M, N, K)
 
-        packw_bn = cfg["tile_x"].size[-1]
-        packw_shape = (out_dim // packw_bn, in_dim, packw_bn)
-        packw = tvm.compute(packw_shape,
-                            lambda z, y, x: weight[z * packw_bn + x, y], name="packed_weight")
+    packw_bn = cfg["tile_x"].size[-1]
+    packw_shape = (N // packw_bn, K, packw_bn)
+    packw = tvm.compute(packw_shape,
+                        lambda z, y, x: weight[z * packw_bn + x, y], name="packed_weight")
 
-        k = tvm.reduce_axis((0, in_dim), name="k")
-        C = tvm.compute((batch, out_dim),
-                        lambda y, x: tvm.sum(
-                            data[y, k].astype(out_dtype) *
-                            packw[x // packw_bn, k, x % packw_bn].astype(out_dtype),
-                            axis=k),
-                        tag="dense_pack")
+    k = tvm.reduce_axis((0, K), name="k")
+    C = tvm.compute((M, N),
+                    lambda y, x: tvm.sum(
+                        data[y, k].astype(out_dtype) *
+                        packw[x // packw_bn, k, x % packw_bn].astype(out_dtype),
+                        axis=k),
+                    tag="dense_pack")
     if bias is not None:
-        C = tvm.compute((batch, out_dim), lambda i, j: C[i, j] + bias[j].astype(out_dtype),
+        C = tvm.compute((M, N), lambda i, j: C[i, j] + bias[j].astype(out_dtype),
                         tag=tag.BROADCAST)
     return C
 
@@ -77,34 +80,30 @@ def _declaration_dense_pack(cfg, data, weight, bias=None, out_dtype=None):
 # Declare dense compute without packing weight
 @autotvm.register_topi_compute(nn.dense, "cpu", "direct_nopack")
 def _declaration_dense_nopack(cfg, data, weight, bias=None, out_dtype=None):
-    target = tvm.target.current_target()
-    if "cblas" in target.libs:
-        C = cblas.matmul(data, weight, False, True)
-    else:
-        if out_dtype is None:
-            out_dtype = data.dtype
-        batch, in_dim = get_const_tuple(data.shape)
-        out_dim, _ = get_const_tuple(weight.shape)
-        # create tuning space
-        cfg.define_split("tile_x", out_dim, num_outputs=2)
-        cfg.define_split("tile_y", batch, num_outputs=2)
-        cfg.define_split("tile_k", in_dim, num_outputs=2)
-        if cfg.is_fallback:
-            _default_dense_nopack_config(cfg, batch, out_dim, in_dim)
+    if out_dtype is None:
+        out_dtype = data.dtype
+    M, K = get_const_tuple(data.shape)
+    N, _ = get_const_tuple(weight.shape)
+    # create tuning space
+    cfg.define_split("tile_y", M, num_outputs=2)
+    cfg.define_split("tile_x", N, num_outputs=2)
+    cfg.define_split("tile_k", K, num_outputs=2)
+    if cfg.is_fallback:
+        _default_dense_nopack_config(cfg, M, N, K)
 
-        vec = cfg["tile_k"].size[-1]
-        k = tvm.reduce_axis((0, in_dim // vec), "k")
-        CC = tvm.compute((batch, out_dim, vec),
-                         lambda z, y, x: tvm.sum(
-                             data[z, k * vec + x].astype(out_dtype) *
-                             weight[y, k * vec + x].astype(out_dtype), axis=k))
+    vec = cfg["tile_k"].size[-1]
+    k = tvm.reduce_axis((0, K // vec), "k")
+    CC = tvm.compute((M, N, vec),
+                     lambda z, y, x: tvm.sum(
+                         data[z, k * vec + x].astype(out_dtype) *
+                         weight[y, k * vec + x].astype(out_dtype), axis=k))
 
-        kk = tvm.reduce_axis((0, vec), "kk")
-        C = tvm.compute((batch, out_dim),
-                        lambda y, x: tvm.sum(CC[y, x, kk], axis=kk),
-                        tag="dense_nopack")
+    kk = tvm.reduce_axis((0, vec), "kk")
+    C = tvm.compute((M, N),
+                    lambda y, x: tvm.sum(CC[y, x, kk], axis=kk),
+                    tag="dense_nopack")
     if bias is not None:
-        C = tvm.compute((batch, out_dim), lambda i, j: C[i, j] + bias[j].astype(out_dtype),
+        C = tvm.compute((M, N), lambda i, j: C[i, j] + bias[j].astype(out_dtype),
                         tag=tag.BROADCAST)
 
     return C

topi/src/topi.cc

@@ -148,6 +148,11 @@ TVM_REGISTER_GLOBAL("topi.exp")
   *rv = exp(args[0]);
   });
 
+TVM_REGISTER_GLOBAL("topi.erf")
+.set_body([](TVMArgs args, TVMRetValue *rv) {
+  *rv = erf(args[0]);
+  });
+
 TVM_REGISTER_GLOBAL("topi.cos")
 .set_body([](TVMArgs args, TVMRetValue *rv) {
   *rv = cos(args[0]);
@@ -157,7 +162,6 @@ TVM_REGISTER_GLOBAL("topi.sin")
 .set_body([](TVMArgs args, TVMRetValue *rv) {
   *rv = sin(args[0]);
   });
-
 TVM_REGISTER_GLOBAL("topi.tanh")
 .set_body([](TVMArgs args, TVMRetValue *rv) {
   *rv = tanh(args[0]);

topi/tests/python/test_topi_basic.py

@@ -36,6 +36,7 @@ def test_ewise():
         assert B.op.body[0].name == name
 
     test_apply(topi.exp, "exp")
+    test_apply(topi.erf, "erf")
     test_apply(topi.tanh, "tanh")
     test_apply(topi.sigmoid, "sigmoid")
     test_apply(topi.log, "log")

topi/tests/python/test_topi_math.py

@@ -15,6 +15,7 @@
 # specific language governing permissions and limitations
 # under the License.
 import numpy as np
+import scipy
 import tvm
 import topi
 import topi.testing
@@ -86,6 +87,7 @@ def test_ewise():
     test_apply(topi.rsqrt, "rsqrt", lambda x: np.ones_like(x) / np.sqrt(x), 0, 100, skip_name_check=True)
     test_apply(topi.cos, "cos", np.cos, -2.0*np.pi, 2.0*np.pi)
     test_apply(topi.sin, "sin", np.sin, -2.0*np.pi, 2.0*np.pi)
+    test_apply(topi.erf, "erf", scipy.special.erf, -.1, .1, dtype="float32")
 
 
 def test_cast():