--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/clang/test/CodeGen/arm64-aapcs-arguments.c	Thu Feb 13 15:10:13 2020 +0900
@@ -0,0 +1,51 @@
+// RUN: %clang_cc1 -triple aarch64-linux-gnu -target-feature +neon -target-abi aapcs -ffreestanding -fallow-half-arguments-and-returns -emit-llvm -w -o - %s | FileCheck %s
+
+// AAPCS clause C.8 says: If the argument has an alignment of 16 then the NGRN
+// is rounded up to the next even number.
+
+// CHECK: void @test1(i32 %x0, i128 %x2_x3, i128 %x4_x5, i128 %x6_x7, i128 %sp.coerce)
+typedef union { __int128 a; } Small;
+void test1(int x0, __int128 x2_x3, __int128 x4_x5, __int128 x6_x7, Small sp) {
+}
+
+
+// CHECK: void @test2(i32 %x0, i128 %x2_x3.coerce, i32 %x4, i128 %x6_x7.coerce, i32 %sp, i128 %sp16.coerce)
+void test2(int x0, Small x2_x3, int x4, Small x6_x7, int sp, Small sp16) {
+}
+
+// We coerce HFAs into a contiguous [N x double] type if they're going on the
+// stack in order to avoid holes. Make sure we get all of them, and not just the
+// first:
+
+// CHECK: void @test3([4 x float] %s0_s3.coerce, float %s4, [4 x float] %sp.coerce, [4 x float] %sp16.coerce)
+typedef struct { float arr[4]; } HFA;
+void test3(HFA s0_s3, float s4, HFA sp, HFA sp16) {
+}
+
+
+// However, we shouldn't perform the [N x double] coercion on types which have
+// sufficient alignment to avoid holes on their own. We could coerce to [N x
+// fp128] or something, but leaving them as-is retains more information for
+// users to debug.
+
+//  CHECK: void @test4([3 x <16 x i8>] %v0_v2.coerce, [3 x <16 x i8>] %v3_v5.coerce, [3 x <16 x i8>] %sp.coerce, double %sp48, [3 x <16 x i8>] %sp64.coerce)
+typedef __attribute__((neon_vector_type(16))) signed char int8x16_t;
+typedef struct { int8x16_t arr[3]; } BigHFA;
+void test4(BigHFA v0_v2, BigHFA v3_v5, BigHFA sp, double sp48, BigHFA sp64) {
+}
+
+// It's the job of the argument *consumer* to perform the required sign & zero
+// extensions under AAPCS. There shouldn't be
+
+// CHECK: define i8 @test5(i8 %a, i16 %b)
+unsigned char test5(unsigned char a, signed short b) {
+}
+
+// __fp16 can be used as a function argument or return type (ACLE 2.0)
+// CHECK: define half @test_half(half %{{.*}})
+__fp16 test_half(__fp16 A) { }
+
+// __fp16 is a base type for homogeneous floating-point aggregates for AArch64 (but not 32-bit ARM).
+// CHECK: define %struct.HFA_half @test_half_hfa([4 x half] %{{.*}})
+struct HFA_half { __fp16 a[4]; };
+struct HFA_half test_half_hfa(struct HFA_half A) { }