[ARM] Fix arm_neon.h with -flax-vector-conversions=none, part 3

It's completely impossible to check that I've actually found all the
issues, due to the use of macros in arm_neon.h, but hopefully this time
it'll take more than a few hours for someone to find another issue.

I have no idea why, but apparently there's a rule that some, but not
all, builtins which should take an fp16 vector actually take an int8
vector as an argument.  Fix this, and add test coverage.

Differential Revision: https://reviews.llvm.org/D68838

llvm-svn: 375179

clang/test/CodeGen/aarch64-v8.2a-neon-intrinsics.c

@@ -1,5 +1,5 @@
 // RUN: %clang_cc1 -triple arm64-none-linux-gnu -target-feature +neon -target-feature +fullfp16 -target-feature +v8.2a\
-// RUN: -fallow-half-arguments-and-returns -S -disable-O0-optnone -emit-llvm -o - %s \
+// RUN: -fallow-half-arguments-and-returns -flax-vector-conversions=none -S -disable-O0-optnone -emit-llvm -o - %s \
 // RUN: | opt -S -mem2reg \
 // RUN: | FileCheck %s
 

clang/utils/TableGen/NeonEmitter.cpp

@@ -1442,7 +1442,8 @@ void Intrinsic::emitBodyAsBuiltinCall() {
     }
 
     // Check if an explicit cast is needed.
-    if (CastToType.isVector() && LocalCK == ClassB) {
+    if (CastToType.isVector() &&
+        (LocalCK == ClassB || (T.isHalf() && !T.isScalarForMangling()))) {
       CastToType.makeInteger(8, true);
       Arg = "(" + CastToType.str() + ")" + Arg;
     } else if (CastToType.isVector() && LocalCK == ClassI) {