[AMDGPU] Enable typechecks for __builtin_amdgcn_raw_ptr_buffer_atomic_fadd_v2f16 (#166547)

We didn't remove the `t` for this builtin in the past due to not being
sure if we should use `float16/half`.

This patch doesn't fix the _Float16/half question, I'll address that in
a separate patch later (after discussing the options on our weekly
meeting). At the moment we maintain the `h` for this builtin (which is
likely not what we want for HIP).

Author: jmmartinez

clang/include/clang/Basic/BuiltinsAMDGPU.def

@@ -180,7 +180,7 @@ BUILTIN(__builtin_amdgcn_raw_buffer_load_b128, "V4UiQbiiIi", "n")
 BUILTIN(__builtin_amdgcn_raw_ptr_buffer_atomic_add_i32, "iiQbiiIi", "")
 
 TARGET_BUILTIN(__builtin_amdgcn_raw_ptr_buffer_atomic_fadd_f32, "ffQbiiIi", "", "atomic-fadd-rtn-insts")
-TARGET_BUILTIN(__builtin_amdgcn_raw_ptr_buffer_atomic_fadd_v2f16, "V2hV2hQbiiIi", "t", "atomic-buffer-global-pk-add-f16-insts")
+TARGET_BUILTIN(__builtin_amdgcn_raw_ptr_buffer_atomic_fadd_v2f16, "V2hV2hQbiiIi", "", "atomic-buffer-global-pk-add-f16-insts")
 
 TARGET_BUILTIN(__builtin_amdgcn_raw_ptr_buffer_atomic_fmin_f32, "ffQbiiIi", "", "atomic-fmin-fmax-global-f32")
 TARGET_BUILTIN(__builtin_amdgcn_raw_ptr_buffer_atomic_fmax_f32, "ffQbiiIi", "", "atomic-fmin-fmax-global-f32")

clang/test/SemaHIP/builtins-amdgcn-raw-buffer-atomic-add.hip

@@ -14,5 +14,9 @@ __device__ void test_raw_ptr_atomics(__amdgpu_buffer_rsrc_t rsrc, int i32, float
 __device__ void test_raw_ptr_atomics_err(__amdgpu_buffer_rsrc_t rsrc, int i32, float f32, float16x2_t v2f16, int offset, int soffset) {
   i32 = __builtin_amdgcn_raw_ptr_buffer_atomic_add_i32(i32, rsrc, offset, soffset, 0, 4); // expected-error{{too many arguments to function call}}
   f32 = __builtin_amdgcn_raw_ptr_buffer_atomic_fadd_f32(f32, rsrc, offset, soffset, 0, 4); // expected-error{{too many arguments to function call}}
-  v2f16 = __builtin_amdgcn_raw_ptr_buffer_atomic_fadd_v2f16(v2f16, rsrc, offset, soffset, 0, 4);
+  v2f16 = __builtin_amdgcn_raw_ptr_buffer_atomic_fadd_v2f16(v2f16, rsrc, offset, soffset, 0, 4); // expected-error{{too many arguments to function call}}
+}
+
+__device__ void test_raw_ptr_atomics_f16_retty(__amdgpu_buffer_rsrc_t rsrc, int i32, float f32, float16x2_t v2f16, int offset, int soffset) {
+  v2f16 = __builtin_amdgcn_raw_ptr_buffer_atomic_fadd_v2f16(v2f16, rsrc, offset, soffset, 0);
 }