Add basic support for C++ name mangling according to the Itanium C++
ABI to the CodeGen library. Since C++ code-generation is so
incomplete, we can't exercise much of this mangling code. However, a
few smoke tests show that it's doing the same thing as GCC. When C++
codegen matures, we'll extend the ABI tester to verify name-mangling
as well, and complete the implementation here.

At this point, the major client of name mangling is in the uses of the
new "overloadable" attribute in C, which allows overloading. Any
"overloadable" function in C (or in an extern "C" block in C++) will
be mangled the same way that the corresponding C++ function would be
mangled.



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@64413 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/test/CodeGen/overloadable.c b/test/CodeGen/overloadable.c
new file mode 100644
index 0000000..6b1cb35
--- /dev/null
+++ b/test/CodeGen/overloadable.c
@@ -0,0 +1,24 @@
+// RUN: clang -emit-llvm %s -o - | grep _Z1fPA10_1X
+int __attribute__((overloadable)) f(int x) { return x; }
+float __attribute__((overloadable)) f(float x) { return x; }
+double __attribute__((overloadable)) f(double x) { return x; }
+double _Complex __attribute__((overloadable)) f(double _Complex x) { return x; }
+typedef short v4hi __attribute__ ((__vector_size__ (8)));
+v4hi __attribute__((overloadable)) f(v4hi x) { return x; }
+
+struct X { };
+void  __attribute__((overloadable)) f(struct X (*ptr)[10]) { }
+
+int main() {
+  int iv = 17;
+  float fv = 3.0f;
+  double dv = 4.0;
+  double _Complex cdv;
+  v4hi vv;
+
+  iv = f(iv);
+  fv = f(fv);
+  dv = f(dv);
+  cdv = f(cdv);
+  vv = f(vv);
+}