[SYCL] Fix as() function implementation for a swizzle vector (#2966)

Signed-off-by: mdimakov <[email protected]>

Author: maximdimakov

sycl/include/CL/sycl/types.hpp

@@ -1817,11 +1817,16 @@ class SwizzleOp {
     return Tmp.template convert<convertT, roundingMode>();
   }
 
-  template <typename asT>
-  typename detail::enable_if_t<asT::getNumElements() == getNumElements(), asT>
-  as() const {
+  template <typename asT> asT as() const {
     // First materialize the swizzle to vec_t and then apply as() to it.
     vec_t Tmp = *this;
+    static_assert((sizeof(Tmp) == sizeof(asT)),
+                  "The new SYCL vec type must have the same storage size in "
+                  "bytes as this SYCL swizzled vec");
+    static_assert(
+        detail::is_contained<asT, detail::gtl::vector_basic_list>::value,
+        "asT must be SYCL vec of a different element type and "
+        "number of elements specified by asT");
     return Tmp.template as<asT>();
   }
 

sycl/test/basic_tests/vectors/vectors.cpp

@@ -64,6 +64,12 @@ int main() {
   unsigned long long ull_val = ull_vec.template swizzle<cl::sycl::elem::s0>();
   assert(ull_val == ull_ref);
 
+  // Check that the function as() in swizzle vec class is working correctly
+  cl::sycl::vec<int8_t, 2> inputVec = cl::sycl::vec<int8_t, 2>(0, 1);
+  auto asVec =
+      inputVec.template swizzle<cl::sycl::elem::s0, cl::sycl::elem::s1>()
+          .template as<cl::sycl::vec<int16_t, 1>>();
+
   // Check that [u]long[n] type aliases match vec<[unsigned] long, n> types.
   assert((std::is_same<cl::sycl::vec<long, 2>, cl::sycl::long2>::value));
   assert((std::is_same<cl::sycl::vec<long, 3>, cl::sycl::long3>::value));