Revert unneeded cbrt<bfloat16> support

Author: joeatodd

sycl/doc/syclcompat/README.md

@@ -1795,7 +1795,9 @@ inline std::enable_if_t<ValueT::size() == 2, ValueT> isnan(const ValueT a);
 
 // cbrt function wrapper.
 template <typename ValueT>
-inline std::enable_if_t<syclcompat::is_floating_point_v<ValueT>, ValueT>
+inline std::enable_if_t<std::is_floating_point_v<ValueT> ||
+                            std::is_same_v<ValueT, sycl::half>,
+                        ValueT>
 cbrt(ValueT val);
 
 // For floating-point types, `float` or `double` arguments are acceptable.

sycl/include/syclcompat/math.hpp

@@ -721,13 +721,11 @@ inline std::enable_if_t<ValueT::size() == 2, ValueT> isnan(const ValueT a) {
 
 /// cbrt function wrapper.
 template <typename ValueT>
-inline std::enable_if_t<syclcompat::is_floating_point_v<ValueT>, ValueT>
+inline std::enable_if_t<std::is_floating_point_v<ValueT> ||
+                            std::is_same_v<ValueT, sycl::half>,
+                        ValueT>
 cbrt(ValueT val) {
-  if constexpr (std::is_same_v<sycl::ext::oneapi::bfloat16, ValueT>) {
-    return static_cast<ValueT>(sycl::cbrt(static_cast<float>(val)));
-  } else {
-    return sycl::cbrt(static_cast<ValueT>(val));
-  }
+  return sycl::cbrt(static_cast<ValueT>(val));
 }
 
 // min/max function overloads.

sycl/test-e2e/syclcompat/common.hpp

@@ -63,8 +63,14 @@ using value_type_list =
 #endif
 >;
 
-using fp_type_list =
-    std::tuple<float, double, sycl::half, sycl::ext::oneapi::bfloat16>;
+using fp_type_list_no_bfloat16 = std::tuple<float, double, sycl::half>;
+
+using fp_type_list = std::tuple<float, double, sycl::half
+
+#ifdef SYCL_EXT_ONEAPI_BFLOAT16_MATH_FUNCTIONS
+                ,sycl::ext::oneapi::bfloat16
+#endif
+>;
 
 using marray_type_list =
     std::tuple<char, signed char, short, int, long, long long, unsigned char,

sycl/test-e2e/syclcompat/math/math_ops.cpp

@@ -375,7 +375,7 @@ int main() {
   test_syclcompat_pow<double, int>();
 
   INSTANTIATE_ALL_TYPES(fp_type_list, test_syclcompat_relu);
-  INSTANTIATE_ALL_TYPES(fp_type_list, test_syclcompat_cbrt);
+  INSTANTIATE_ALL_TYPES(fp_type_list_no_bfloat16, test_syclcompat_cbrt);
 
   INSTANTIATE_ALL_CONTAINER_TYPES(fp_type_list, sycl::vec, test_isnan);
   INSTANTIATE_ALL_CONTAINER_TYPES(fp_type_list, sycl::marray, test_isnan);