Allow __fp16 as a function arg or return type for AArch64

ACLE 2.0 allows __fp16 to be used as a function argument or return
type. This enables this for AArch64.

This also fixes an existing bug that causes clang to not allow
homogeneous floating-point aggregates with a base type of __fp16. This
is valid for AAPCS64, but not for AAPCS-VFP.

llvm-svn: 216558

clang/lib/Frontend/CompilerInvocation.cpp

@@ -1500,6 +1500,8 @@ static void ParseLangArgs(LangOptions &Opts, ArgList &Args, InputKind IK,
   Opts.CurrentModule = Args.getLastArgValue(OPT_fmodule_name);
   Opts.ImplementationOfModule =
       Args.getLastArgValue(OPT_fmodule_implementation_of);
+  Opts.NativeHalfType = Opts.NativeHalfType;
+  Opts.HalfArgsAndReturns = Args.hasArg(OPT_fallow_half_arguments_and_returns);
 
   if (!Opts.CurrentModule.empty() && !Opts.ImplementationOfModule.empty() &&
       Opts.CurrentModule != Opts.ImplementationOfModule) {