[analyzer][UninitializedObjectChecker] PR41611: Regard vector types as primitive

https://bugs.llvm.org/show_bug.cgi?id=41611

Similarly to D61106, the checker ran over an llvm_unreachable for vector types:

struct VectorSizeLong {
  VectorSizeLong() {}
  __attribute__((__vector_size__(16))) long x;
};

void __vector_size__LongTest() {
  VectorSizeLong v;
}
Since, according to my short research,

"The vector_size attribute is only applicable to integral and float scalars,
although arrays, pointers, and function return values are allowed in conjunction
with this construct."
[src: https://gcc.gnu.org/onlinedocs/gcc-4.6.1/gcc/Vector-Extensions.html#Vector-Extensions]

vector types are safe to regard as primitive.

Differential Revision: https://reviews.llvm.org/D61246

llvm-svn: 359539
diff --git a/clang/test/Analysis/cxx-uninitialized-object.cpp b/clang/test/Analysis/cxx-uninitialized-object.cpp
index 86f2ecd..a811319 100644
--- a/clang/test/Analysis/cxx-uninitialized-object.cpp
+++ b/clang/test/Analysis/cxx-uninitialized-object.cpp
@@ -1132,7 +1132,7 @@
 }
 
 //===----------------------------------------------------------------------===//
-// _Atomic tests.
+// "Esoteric" primitive type tests.
 //===----------------------------------------------------------------------===//
 
 struct MyAtomicInt {
@@ -1142,6 +1142,17 @@
   MyAtomicInt() {} // expected-warning{{1 uninitialized field}}
 };
 
-void entry() {
+void _AtomicTest() {
   MyAtomicInt b;
 }
+
+struct VectorSizeLong {
+  VectorSizeLong() {}
+  __attribute__((__vector_size__(16))) long x;
+};
+
+void __vector_size__LongTest() {
+  // TODO: Warn for v.x.
+  VectorSizeLong v;
+  v.x[0] = 0;
+}