[clang] [AMDGPU] Enable typechecks for __builtin_amdgcn_raw_ptr_buffer_atomic_fadd_v2f16 (PR #166547)

[Juan Manuel Martinez Caamaño via cfe-commits]

https://github.com/jmmartinez created https://github.com/llvm/llvm-project/pull/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).

`_Float16` and `half` with`cl_khr_fp16` are mostly compatible; but one of the subtle differences is that the later is promoted to `double` when passed to `printf` (https://godbolt.org/z/Kq978dWxz).

>From 51e2c5ce52873db0e2bf26cf758c1565d0303525 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Juan=20Manuel=20Martinez=20Caama=C3=B1o?=
 <jmartinezcaamao at gmail.com>
Date: Fri, 31 Oct 2025 11:52:09 +0100
Subject: [PATCH] [AMDGPU] Enable typechecks for
 __builtin_amdgcn_raw_ptr_buffer_atomic_fadd_v2f16

---
 clang/include/clang/Basic/BuiltinsAMDGPU.def                | 2 +-
 .../test/SemaHIP/builtins-amdgcn-raw-buffer-atomic-add.hip  | 6 +++++-
 2 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/clang/include/clang/Basic/BuiltinsAMDGPU.def b/clang/include/clang/Basic/BuiltinsAMDGPU.def
index 36cb527a9c806..2b6fcb1fd479b 100644
--- a/clang/include/clang/Basic/BuiltinsAMDGPU.def
+++ b/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")
diff --git a/clang/test/SemaHIP/builtins-amdgcn-raw-buffer-atomic-add.hip b/clang/test/SemaHIP/builtins-amdgcn-raw-buffer-atomic-add.hip
index 8ee64d486f4f4..fea86162c801d 100644
--- a/clang/test/SemaHIP/builtins-amdgcn-raw-buffer-atomic-add.hip
+++ b/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);
 }