[OpenCL] Add atomic_half type builtins

[haonanya]

Summary

Add atomic_half types and builtins operating on the types

[svenvh]

Looks good at a first quick glance, but please fix the formatting errors that are reported on the lines that you are adding.

[haonanya]

Fix format issue

[svenvh]

LGTM

[haonanya]

Hi, svenvh. Thanks for your review.
Could you please help to submit the patch if there are no more inputs?

clang/lib/Headers/opencl-c.h

 uintptr_t __ovld atomic_fetch_add_explicit(volatile __global atomic_uintptr_t *object, ptrdiff_t operand, memory_order order, memory_scope scope);
 uintptr_t __ovld atomic_fetch_sub_explicit(volatile __local atomic_uintptr_t *object, ptrdiff_t operand, memory_order order, memory_scope scope);
 #endif //defined(cl_khr_int64_base_atomics) && defined(cl_khr_int64_extended_atomics)
 #endif // (__OPENCL_C_VERSION__ >= CL_VERSION_3_0 || __OPENCL_CPP_VERSION__ >= 202100)
 
 // The functionality added by cl_ext_float_atomics extension
 #if defined(cl_ext_float_atomics)
 
+#if defined(__opencl_c_ext_fp16_global_atomic_load_store)
+void __ovld atomic_store(volatile __global atomic_half *object, half operand);
+void __ovld atomic_store_explicit(volatile __global atomic_half *object,
+                                  half operand, memory_order order);
+void __ovld atomic_store_explicit(volatile __global atomic_half *object,
+                                  half operand, memory_order order,
+                                  memory_scope scope);
+half __ovld atomic_load(volatile __global atomic_half *object);
+half __ovld atomic_load_explicit(volatile __global atomic_half *object,
+                                 memory_order order);
+half __ovld atomic_load_explicit(volatile __global atomic_half *object,
+                                 memory_order order, memory_scope scope);
+half __ovld atomic_exchange(volatile __global atomic_half *object,
+                            half operand);
+half __ovld atomic_exchange_explicit(volatile __global atomic_half *object,
+                                     half operand, memory_order order);
+half __ovld atomic_exchange_explicit(volatile __global atomic_half *object,
+                                     half operand, memory_order order,
+                                     memory_scope scope);
+#endif // defined(__opencl_c_ext_fp16_global_atomic_load_store)
+
+#if defined(__opencl_c_ext_fp16_local_atomic_load_store)
+void __ovld atomic_store(volatile __local atomic_half *object, half operand);
+void __ovld atomic_store_explicit(volatile __local atomic_half *object,
+                                  half operand, memory_order order);
+void __ovld atomic_store_explicit(volatile __local atomic_half *object,
+                                  half operand, memory_order order,
+                                  memory_scope scope);
+half __ovld atomic_load(volatile __local atomic_half *object);
+half __ovld atomic_load_explicit(volatile __local atomic_half *object,
+                                 memory_order order);
+half __ovld atomic_load_explicit(volatile __local atomic_half *object,
+                                 memory_order order, memory_scope scope);
+half __ovld atomic_exchange(volatile __local atomic_half *object, half operand);
+half __ovld atomic_exchange_explicit(volatile __local atomic_half *object,
+                                     half operand, memory_order order);
+half __ovld atomic_exchange_explicit(volatile __local atomic_half *object,
+                                     half operand, memory_order order,
+                                     memory_scope scope);
+#endif // defined(__opencl_c_ext_fp16_local_atomic_load_store)
+
+#if defined(__opencl_c_ext_fp16_global_atomic_load_store) &&                   \
+    defined(__opencl_c_ext_fp16_local_atomic_load_store)
+void __ovld atomic_store(volatile atomic_half *object, half operand);
+void __ovld atomic_store_explicit(volatile atomic_half *object, half operand,
+                                  memory_order order);
+void __ovld atomic_store_explicit(volatile atomic_half *object, half operand,
+                                  memory_order order, memory_scope scope);
+half __ovld atomic_load(volatile atomic_half *object);
+half __ovld atomic_load_explicit(volatile atomic_half *object,
+                                 memory_order order);
+half __ovld atomic_load_explicit(volatile atomic_half *object,
+                                 memory_order order, memory_scope scope);
+half __ovld atomic_exchange(volatile atomic_half *object, half operand);
+half __ovld atomic_exchange_explicit(volatile atomic_half *object, half operand,
+                                     memory_order order);
+half __ovld atomic_exchange_explicit(volatile atomic_half *object, half operand,
+                                     memory_order order, memory_scope scope);
+#endif // defined(__opencl_c_ext_fp16_global_atomic_load_store) &&
+       // defined(__opencl_c_ext_fp16_local_atomic_load_store)
+
+#if defined(__opencl_c_ext_fp16_global_atomic_min_max)
+half __ovld atomic_fetch_min(volatile __global atomic_half *object,
+                             half operand);
+half __ovld atomic_fetch_max(volatile __global atomic_half *object,
+                             half operand);
+half __ovld atomic_fetch_min_explicit(volatile __global atomic_half *object,
+                                      half operand, memory_order order);
+half __ovld atomic_fetch_max_explicit(volatile __global atomic_half *object,
+                                      half operand, memory_order order);
+half __ovld atomic_fetch_min_explicit(volatile __global atomic_half *object,
+                                      half operand, memory_order order,
+                                      memory_scope scope);
+half __ovld atomic_fetch_max_explicit(volatile __global atomic_half *object,
+                                      half operand, memory_order order,
+                                      memory_scope scope);
+#endif // defined(__opencl_c_ext_fp16_global_atomic_min_max)
+
+#if defined(__opencl_c_ext_fp16_local_atomic_min_max)
+half __ovld atomic_fetch_min(volatile __local atomic_half *object,
+                             half operand);
+half __ovld atomic_fetch_max(volatile __local atomic_half *object,
+                             half operand);
+half __ovld atomic_fetch_min_explicit(volatile __local atomic_half *object,
+                                      half operand, memory_order order);
+half __ovld atomic_fetch_max_explicit(volatile __local atomic_half *object,
+                                      half operand, memory_order order);
+half __ovld atomic_fetch_min_explicit(volatile __local atomic_half *object,
+                                      half operand, memory_order order,
+                                      memory_scope scope);
+half __ovld atomic_fetch_max_explicit(volatile __local atomic_half *object,
+                                      half operand, memory_order order,
+                                      memory_scope scope);
+#endif // defined(__opencl_c_ext_fp16_local_atomic_min_max)
+
+#if defined(__opencl_c_ext_fp16_global_atomic_min_max) &&                      \
+    defined(__opencl_c_ext_fp16_local_atomic_min_max)
+half __ovld atomic_fetch_min(volatile atomic_half *object, half operand);
+half __ovld atomic_fetch_max(volatile atomic_half *object, half operand);
+half __ovld atomic_fetch_min_explicit(volatile atomic_half *object,
+                                      half operand, memory_order order);
+half __ovld atomic_fetch_max_explicit(volatile atomic_half *object,
+                                      half operand, memory_order order);
+half __ovld atomic_fetch_min_explicit(volatile atomic_half *object,
+                                      half operand, memory_order order,
+                                      memory_scope scope);
+half __ovld atomic_fetch_max_explicit(volatile atomic_half *object,
+                                      half operand, memory_order order,
+                                      memory_scope scope);
+#endif // defined(__opencl_c_ext_fp16_global_atomic_min_max) &&                \
+    defined(__opencl_c_ext_fp16_local_atomic_min_max)
+
 #if defined(__opencl_c_ext_fp32_global_atomic_min_max)
 float __ovld atomic_fetch_min(volatile __global atomic_float *object,
                               float operand);
 float __ovld atomic_fetch_max(volatile __global atomic_float *object,
                               float operand);
 float __ovld atomic_fetch_min_explicit(volatile __global atomic_float *object,
                                        float operand, memory_order order);
 float __ovld atomic_fetch_max_explicit(volatile __global atomic_float *object,
double __ovld atomic_fetch_min_explicit(volatile atomic_double *object,
                                         double operand, memory_order order,
                                         memory_scope scope);
 double __ovld atomic_fetch_max_explicit(volatile atomic_double *object,
                                         double operand, memory_order order,
                                         memory_scope scope);
 #endif // defined(__opencl_c_ext_fp64_global_atomic_min_max) &&                \
     defined(__opencl_c_ext_fp64_local_atomic_min_max)
 
+#if defined(__opencl_c_ext_fp16_global_atomic_add)
+half __ovld atomic_fetch_add(volatile __global atomic_half *object,
+                             half operand);
+half __ovld atomic_fetch_sub(volatile __global atomic_half *object,
+                             half operand);
+half __ovld atomic_fetch_add_explicit(volatile __global atomic_half *object,
+                                      half operand, memory_order order);
+half __ovld atomic_fetch_sub_explicit(volatile __global atomic_half *object,
+                                      half operand, memory_order order);
+half __ovld atomic_fetch_add_explicit(volatile __global atomic_half *object,
+                                      half operand, memory_order order,
+                                      memory_scope scope);
+half __ovld atomic_fetch_sub_explicit(volatile __global atomic_half *object,
+                                      half operand, memory_order order,
+                                      memory_scope scope);
+#endif // defined(__opencl_c_ext_fp16_global_atomic_add)
+
+#if defined(__opencl_c_ext_fp16_local_atomic_add)
+half __ovld atomic_fetch_add(volatile __local atomic_half *object,
+                             half operand);
+half __ovld atomic_fetch_sub(volatile __local atomic_half *object,
+                             half operand);
+half __ovld atomic_fetch_add_explicit(volatile __local atomic_half *object,
+                                      half operand, memory_order order);
+half __ovld atomic_fetch_sub_explicit(volatile __local atomic_half *object,
+                                      half operand, memory_order order);
+half __ovld atomic_fetch_add_explicit(volatile __local atomic_half *object,
+                                      half operand, memory_order order,
+                                      memory_scope scope);
+half __ovld atomic_fetch_sub_explicit(volatile __local atomic_half *object,
+                                      half operand, memory_order order,
+                                      memory_scope scope);
+#endif // defined(__opencl_c_ext_fp16_local_atomic_add)
+
+#if defined(__opencl_c_ext_fp16_global_atomic_add) &&                          \
+    defined(__opencl_c_ext_fp16_local_atomic_add)
+half __ovld atomic_fetch_add(volatile atomic_half *object, half operand);
+half __ovld atomic_fetch_sub(volatile atomic_half *object, half operand);
+half __ovld atomic_fetch_add_explicit(volatile atomic_half *object,
+                                      half operand, memory_order order);
+half __ovld atomic_fetch_sub_explicit(volatile atomic_half *object,
+                                      half operand, memory_order order);
+half __ovld atomic_fetch_add_explicit(volatile atomic_half *object,
+                                      half operand, memory_order order,
+                                      memory_scope scope);
+half __ovld atomic_fetch_sub_explicit(volatile atomic_half *object,
+                                      half operand, memory_order order,
+                                      memory_scope scope);
+#endif // defined(__opencl_c_ext_fp16_global_atomic_add) &&                    \
+    defined(__opencl_c_ext_fp16_local_atomic_add)
+
 #if defined(__opencl_c_ext_fp32_global_atomic_add)
 float __ovld atomic_fetch_add(volatile __global atomic_float *object,
                               float operand);
 float __ovld atomic_fetch_sub(volatile __global atomic_float *object,
                               float operand);
 float __ovld atomic_fetch_add_explicit(volatile __global atomic_float *object,
                                        float operand, memory_order order);
 float __ovld atomic_fetch_sub_explicit(volatile __global atomic_float *object,

clang/lib/Sema/OpenCLBuiltins.td

 def FuncExtKhrInt64BaseAtomics           : FunctionExtension<"cl_khr_int64_base_atomics">;
 def FuncExtKhrInt64ExtendedAtomics       : FunctionExtension<"cl_khr_int64_extended_atomics">;
 def FuncExtKhrMipmapImage                : FunctionExtension<"cl_khr_mipmap_image">;
 def FuncExtKhrMipmapImageWrites          : FunctionExtension<"cl_khr_mipmap_image_writes">;
 def FuncExtKhrGlMsaaSharing              : FunctionExtension<"cl_khr_gl_msaa_sharing">;
 
 def FuncExtOpenCLCPipes                  : FunctionExtension<"__opencl_c_pipes">;
 def FuncExtOpenCLCWGCollectiveFunctions  : FunctionExtension<"__opencl_c_work_group_collective_functions">;
+def FuncExtFloatAtomicsFp16GlobalLoadStore  : FunctionExtension<"cl_ext_float_atomics __opencl_c_ext_fp16_global_atomic_load_store">;
+def FuncExtFloatAtomicsFp16LocalLoadStore   : FunctionExtension<"cl_ext_float_atomics __opencl_c_ext_fp16_local_atomic_load_store">;
+def FuncExtFloatAtomicsFp16GenericLoadStore : FunctionExtension<"cl_ext_float_atomics __opencl_c_ext_fp16_global_atomic_load_store __opencl_c_ext_fp16_local_atomic_load_store">;
+def FuncExtFloatAtomicsFp16GlobalAdd     : FunctionExtension<"cl_ext_float_atomics __opencl_c_ext_fp16_global_atomic_add">;
 def FuncExtFloatAtomicsFp32GlobalAdd     : FunctionExtension<"cl_ext_float_atomics __opencl_c_ext_fp32_global_atomic_add">;
 def FuncExtFloatAtomicsFp64GlobalAdd     : FunctionExtension<"cl_ext_float_atomics __opencl_c_ext_fp64_global_atomic_add">;
+def FuncExtFloatAtomicsFp16LocalAdd      : FunctionExtension<"cl_ext_float_atomics __opencl_c_ext_fp16_local_atomic_add">;
 def FuncExtFloatAtomicsFp32LocalAdd      : FunctionExtension<"cl_ext_float_atomics __opencl_c_ext_fp32_local_atomic_add">;
 def FuncExtFloatAtomicsFp64LocalAdd      : FunctionExtension<"cl_ext_float_atomics __opencl_c_ext_fp64_local_atomic_add">;
+def FuncExtFloatAtomicsFp16GenericAdd    : FunctionExtension<"cl_ext_float_atomics __opencl_c_ext_fp16_local_atomic_add __opencl_c_ext_fp16_global_atomic_add">;
 def FuncExtFloatAtomicsFp32GenericAdd    : FunctionExtension<"cl_ext_float_atomics __opencl_c_ext_fp32_local_atomic_add __opencl_c_ext_fp32_global_atomic_add">;
 def FuncExtFloatAtomicsFp64GenericAdd    : FunctionExtension<"cl_ext_float_atomics __opencl_c_ext_fp64_local_atomic_add __opencl_c_ext_fp64_global_atomic_add">;
+def FuncExtFloatAtomicsFp16GlobalMinMax  : FunctionExtension<"cl_ext_float_atomics __opencl_c_ext_fp16_global_atomic_min_max">;
 def FuncExtFloatAtomicsFp32GlobalMinMax  : FunctionExtension<"cl_ext_float_atomics __opencl_c_ext_fp32_global_atomic_min_max">;
 def FuncExtFloatAtomicsFp64GlobalMinMax  : FunctionExtension<"cl_ext_float_atomics __opencl_c_ext_fp64_global_atomic_min_max">;
+def FuncExtFloatAtomicsFp16LocalMinMax   : FunctionExtension<"cl_ext_float_atomics __opencl_c_ext_fp16_local_atomic_min_max">;
 def FuncExtFloatAtomicsFp32LocalMinMax   : FunctionExtension<"cl_ext_float_atomics __opencl_c_ext_fp32_local_atomic_min_max">;
 def FuncExtFloatAtomicsFp64LocalMinMax   : FunctionExtension<"cl_ext_float_atomics __opencl_c_ext_fp64_local_atomic_min_max">;
+def FuncExtFloatAtomicsFp16GenericMinMax : FunctionExtension<"cl_ext_float_atomics __opencl_c_ext_fp16_local_atomic_min_max __opencl_c_ext_fp16_global_atomic_min_max">;
 def FuncExtFloatAtomicsFp32GenericMinMax : FunctionExtension<"cl_ext_float_atomics __opencl_c_ext_fp32_local_atomic_min_max __opencl_c_ext_fp32_global_atomic_min_max">;
 def FuncExtFloatAtomicsFp64GenericMinMax : FunctionExtension<"cl_ext_float_atomics __opencl_c_ext_fp64_local_atomic_min_max __opencl_c_ext_fp64_global_atomic_min_max">;
 
 // Not a real extension, but a workaround to add C++ for OpenCL specific builtins.
 def FuncExtOpenCLCxx                     : FunctionExtension<"__cplusplus">;
 
 // Multiple extensions
 def FuncExtKhrMipmapWritesAndWrite3d     : FunctionExtension<"cl_khr_mipmap_image_writes cl_khr_3d_image_writes">;

 
 // OpenCL v2.0 s6.13.11: Atomic integer and floating-point types.
 def AtomicInt             : Type<"atomic_int", QualType<"Context.getAtomicType(Context.IntTy)">>;
 def AtomicUInt            : Type<"atomic_uint", QualType<"Context.getAtomicType(Context.UnsignedIntTy)">>;
 def AtomicLong            : Type<"atomic_long", QualType<"Context.getAtomicType(Context.LongTy)">>;
 def AtomicULong           : Type<"atomic_ulong", QualType<"Context.getAtomicType(Context.UnsignedLongTy)">>;
 def AtomicFloat           : Type<"atomic_float", QualType<"Context.getAtomicType(Context.FloatTy)">>;
 def AtomicDouble          : Type<"atomic_double", QualType<"Context.getAtomicType(Context.DoubleTy)">>;
+def AtomicHalf            : Type<"atomic_half", QualType<"Context.getAtomicType(Context.HalfTy)">>;
 def AtomicIntPtr          : Type<"atomic_intptr_t", QualType<"Context.getAtomicType(Context.getIntPtrType())">>;
 def AtomicUIntPtr         : Type<"atomic_uintptr_t", QualType<"Context.getAtomicType(Context.getUIntPtrType())">>;
 def AtomicSize            : Type<"atomic_size_t", QualType<"Context.getAtomicType(Context.getSizeType())">>;
 def AtomicPtrDiff         : Type<"atomic_ptrdiff_t", QualType<"Context.getAtomicType(Context.getPointerDiffType())">>;
 
 def AtomicFlag            : TypedefType<"atomic_flag">;
 def MemoryOrder           : EnumType<"memory_order">;
 def MemoryScope           : EnumType<"memory_scope">;
let MinVersion = CL20 in {
   def : Builtin<"atomic_flag_test_and_set_explicit",
       [Bool, PointerType<VolatileType<AtomicFlag>, GenericAS>, MemoryOrder]>;
   def : Builtin<"atomic_flag_test_and_set_explicit",
       [Bool, PointerType<VolatileType<AtomicFlag>, GenericAS>, MemoryOrder, MemoryScope]>;
 }
 
 // The functionality added by cl_ext_float_atomics extension
 let MinVersion = CL20 in {
+  let Extension = FuncExtFloatAtomicsFp16GlobalLoadStore in {
+    def : Builtin<"atomic_store",
+        [Void, PointerType<VolatileType<AtomicHalf>, GlobalAS>, AtomicHalf]>;
+    def : Builtin<"atomic_store_explicit",
+        [Void, PointerType<VolatileType<AtomicHalf>, GlobalAS>, AtomicHalf, MemoryOrder]>;
+    def : Builtin<"atomic_store_explicit",
+        [Void, PointerType<VolatileType<AtomicHalf>, GlobalAS>, AtomicHalf, MemoryOrder, MemoryScope]>;
+    def : Builtin<"atomic_load",
+        [Half, PointerType<VolatileType<AtomicHalf>, GlobalAS>]>;
+    def : Builtin<"atomic_load_explicit",
+        [Half, PointerType<VolatileType<AtomicHalf>, GlobalAS>, MemoryOrder]>;
+    def : Builtin<"atomic_load_explicit",
+        [Half, PointerType<VolatileType<AtomicHalf>, GlobalAS>, MemoryOrder, MemoryScope]>;
+    def : Builtin<"atomic_exchange",
+        [Half, PointerType<VolatileType<AtomicHalf>, GlobalAS>, Half]>;
+    def : Builtin<"atomic_exchange_explicit",
+        [Half, PointerType<VolatileType<AtomicHalf>, GlobalAS>, Half, MemoryOrder]>;
+    def : Builtin<"atomic_exchange_explicit",
+        [Half, PointerType<VolatileType<AtomicHalf>, GlobalAS>, Half, MemoryOrder, MemoryScope]>;
+  }
+  let Extension = FuncExtFloatAtomicsFp16LocalLoadStore in {
+    def : Builtin<"atomic_store",
+        [Void, PointerType<VolatileType<AtomicHalf>, LocalAS>, AtomicHalf]>;
+    def : Builtin<"atomic_store_explicit",
+        [Void, PointerType<VolatileType<AtomicHalf>, LocalAS>, AtomicHalf, MemoryOrder]>;
+    def : Builtin<"atomic_store_explicit",
+        [Void, PointerType<VolatileType<AtomicHalf>, LocalAS>, AtomicHalf, MemoryOrder, MemoryScope]>;
+    def : Builtin<"atomic_load",
+        [Half, PointerType<VolatileType<AtomicHalf>, LocalAS>]>;
+    def : Builtin<"atomic_load_explicit",
+        [Half, PointerType<VolatileType<AtomicHalf>, LocalAS>, MemoryOrder]>;
+    def : Builtin<"atomic_load_explicit",
+        [Half, PointerType<VolatileType<AtomicHalf>, LocalAS>, MemoryOrder, MemoryScope]>;
+    def : Builtin<"atomic_exchange",
+        [Half, PointerType<VolatileType<AtomicHalf>, LocalAS>, Half]>;
+    def : Builtin<"atomic_exchange_explicit",
+        [Half, PointerType<VolatileType<AtomicHalf>, LocalAS>, Half, MemoryOrder]>;
+    def : Builtin<"atomic_exchange_explicit",
+        [Half, PointerType<VolatileType<AtomicHalf>, LocalAS>, Half, MemoryOrder, MemoryScope]>;
+  }
+  let Extension = FuncExtFloatAtomicsFp16GenericLoadStore in {
+    def : Builtin<"atomic_store",
+        [Void, PointerType<VolatileType<AtomicHalf>, GenericAS>, AtomicHalf]>;
+    def : Builtin<"atomic_store_explicit",
+        [Void, PointerType<VolatileType<AtomicHalf>, GenericAS>, AtomicHalf, MemoryOrder]>;
+    def : Builtin<"atomic_store_explicit",
+        [Void, PointerType<VolatileType<AtomicHalf>, GenericAS>, AtomicHalf, MemoryOrder, MemoryScope]>;
+    def : Builtin<"atomic_load",
+        [Half, PointerType<VolatileType<AtomicHalf>, GenericAS>]>;
+    def : Builtin<"atomic_load_explicit",
+        [Half, PointerType<VolatileType<AtomicHalf>, GenericAS>, MemoryOrder]>;
+    def : Builtin<"atomic_load_explicit",
+        [Half, PointerType<VolatileType<AtomicHalf>, GenericAS>, MemoryOrder, MemoryScope]>;
+    def : Builtin<"atomic_exchange",
+        [Half, PointerType<VolatileType<AtomicHalf>, GenericAS>, Half]>;
+    def : Builtin<"atomic_exchange_explicit",
+        [Half, PointerType<VolatileType<AtomicHalf>, GenericAS>, Half, MemoryOrder]>;
+    def : Builtin<"atomic_exchange_explicit",
+        [Half, PointerType<VolatileType<AtomicHalf>, GenericAS>, Half, MemoryOrder, MemoryScope]>;
+  }
   foreach ModOp = ["add", "sub"] in {
+    let Extension = FuncExtFloatAtomicsFp16GlobalAdd in {
+      def : Builtin<"atomic_fetch_" # ModOp,
+          [Half, PointerType<VolatileType<AtomicFloat>, GlobalAS>, Half]>;
+      def : Builtin<"atomic_fetch_" # ModOp # "_explicit",
+          [Half, PointerType<VolatileType<AtomicFloat>, GlobalAS>, Half, MemoryOrder]>;
+      def : Builtin<"atomic_fetch_" # ModOp # "_explicit",
+          [Half, PointerType<VolatileType<AtomicFloat>, GlobalAS>, Half, MemoryOrder, MemoryScope]>;
+    }
     let Extension = FuncExtFloatAtomicsFp32GlobalAdd in {
       def : Builtin<"atomic_fetch_" # ModOp,
           [Float, PointerType<VolatileType<AtomicFloat>, GlobalAS>, Float]>;
       def : Builtin<"atomic_fetch_" # ModOp # "_explicit",
           [Float, PointerType<VolatileType<AtomicFloat>, GlobalAS>, Float, MemoryOrder]>;
       def : Builtin<"atomic_fetch_" # ModOp # "_explicit",
           [Float, PointerType<VolatileType<AtomicFloat>, GlobalAS>, Float, MemoryOrder, MemoryScope]>;
     }
     let Extension = FuncExtFloatAtomicsFp64GlobalAdd in {
       def : Builtin<"atomic_fetch_" # ModOp,
           [Double, PointerType<VolatileType<AtomicDouble>, GlobalAS>, Double]>;
       def : Builtin<"atomic_fetch_" # ModOp # "_explicit",
           [Double, PointerType<VolatileType<AtomicDouble>, GlobalAS>, Double, MemoryOrder]>;
       def : Builtin<"atomic_fetch_" # ModOp # "_explicit",
           [Double, PointerType<VolatileType<AtomicDouble>, GlobalAS>, Double, MemoryOrder, MemoryScope]>;
     }
+    let Extension = FuncExtFloatAtomicsFp16LocalAdd in {
+      def : Builtin<"atomic_fetch_" # ModOp,
+          [Half, PointerType<VolatileType<AtomicFloat>, LocalAS>, Half]>;
+      def : Builtin<"atomic_fetch_" # ModOp # "_explicit",
+          [Half, PointerType<VolatileType<AtomicFloat>, LocalAS>, Half, MemoryOrder]>;
+      def : Builtin<"atomic_fetch_" # ModOp # "_explicit",
+          [Half, PointerType<VolatileType<AtomicFloat>, LocalAS>, Half, MemoryOrder, MemoryScope]>;
+    }
     let Extension = FuncExtFloatAtomicsFp32LocalAdd in {
       def : Builtin<"atomic_fetch_" # ModOp,
           [Float, PointerType<VolatileType<AtomicFloat>, LocalAS>, Float]>;
       def : Builtin<"atomic_fetch_" # ModOp # "_explicit",
           [Float, PointerType<VolatileType<AtomicFloat>, LocalAS>, Float, MemoryOrder]>;
       def : Builtin<"atomic_fetch_" # ModOp # "_explicit",
           [Float, PointerType<VolatileType<AtomicFloat>, LocalAS>, Float, MemoryOrder, MemoryScope]>;
     }
     let Extension = FuncExtFloatAtomicsFp64LocalAdd in {
       def : Builtin<"atomic_fetch_" # ModOp,
           [Double, PointerType<VolatileType<AtomicDouble>, LocalAS>, Double]>;
       def : Builtin<"atomic_fetch_" # ModOp # "_explicit",
           [Double, PointerType<VolatileType<AtomicDouble>, LocalAS>, Double, MemoryOrder]>;
       def : Builtin<"atomic_fetch_" # ModOp # "_explicit",
           [Double, PointerType<VolatileType<AtomicDouble>, LocalAS>, Double, MemoryOrder, MemoryScope]>;
     }
+    let Extension = FuncExtFloatAtomicsFp16GenericAdd in {
+      def : Builtin<"atomic_fetch_" # ModOp,
+          [Half, PointerType<VolatileType<AtomicFloat>, GenericAS>, Half]>;
+      def : Builtin<"atomic_fetch_" # ModOp # "_explicit",
+          [Half, PointerType<VolatileType<AtomicFloat>, GenericAS>, Half, MemoryOrder]>;
+      def : Builtin<"atomic_fetch_" # ModOp # "_explicit",
+          [Half, PointerType<VolatileType<AtomicFloat>, GenericAS>, Half, MemoryOrder, MemoryScope]>;
+    }
     let Extension = FuncExtFloatAtomicsFp32GenericAdd in {
       def : Builtin<"atomic_fetch_" # ModOp,
           [Float, PointerType<VolatileType<AtomicFloat>, GenericAS>, Float]>;
       def : Builtin<"atomic_fetch_" # ModOp # "_explicit",
           [Float, PointerType<VolatileType<AtomicFloat>, GenericAS>, Float, MemoryOrder]>;
       def : Builtin<"atomic_fetch_" # ModOp # "_explicit",
           [Float, PointerType<VolatileType<AtomicFloat>, GenericAS>, Float, MemoryOrder, MemoryScope]>;
     }
     let Extension = FuncExtFloatAtomicsFp64GenericAdd in {
       def : Builtin<"atomic_fetch_" # ModOp,
           [Double, PointerType<VolatileType<AtomicDouble>, GenericAS>, Double]>;
       def : Builtin<"atomic_fetch_" # ModOp # "_explicit",
           [Double, PointerType<VolatileType<AtomicDouble>, GenericAS>, Double, MemoryOrder]>;
       def : Builtin<"atomic_fetch_" # ModOp # "_explicit",
           [Double, PointerType<VolatileType<AtomicDouble>, GenericAS>, Double, MemoryOrder, MemoryScope]>;
     }
   }
   foreach ModOp = ["min", "max"] in {
+    let Extension = FuncExtFloatAtomicsFp16GlobalMinMax in {
+      def : Builtin<"atomic_fetch_" # ModOp,
+          [Half, PointerType<VolatileType<AtomicHalf>, GlobalAS>, Half]>;
+      def : Builtin<"atomic_fetch_" # ModOp # "_explicit",
+          [Half, PointerType<VolatileType<AtomicHalf>, GlobalAS>, Half, MemoryOrder]>;
+      def : Builtin<"atomic_fetch_" # ModOp # "_explicit",
+          [Half, PointerType<VolatileType<AtomicHalf>, GlobalAS>, Half, MemoryOrder, MemoryScope]>;
+    }
     let Extension = FuncExtFloatAtomicsFp32GlobalMinMax in {
       def : Builtin<"atomic_fetch_" # ModOp,
           [Float, PointerType<VolatileType<AtomicFloat>, GlobalAS>, Float]>;
       def : Builtin<"atomic_fetch_" # ModOp # "_explicit",
           [Float, PointerType<VolatileType<AtomicFloat>, GlobalAS>, Float, MemoryOrder]>;
       def : Builtin<"atomic_fetch_" # ModOp # "_explicit",
           [Float, PointerType<VolatileType<AtomicFloat>, GlobalAS>, Float, MemoryOrder, MemoryScope]>;
     }
     let Extension = FuncExtFloatAtomicsFp64GlobalMinMax in {
       def : Builtin<"atomic_fetch_" # ModOp,
           [Double, PointerType<VolatileType<AtomicDouble>, GlobalAS>, Double]>;
       def : Builtin<"atomic_fetch_" # ModOp # "_explicit",
           [Double, PointerType<VolatileType<AtomicDouble>, GlobalAS>, Double, MemoryOrder]>;
       def : Builtin<"atomic_fetch_" # ModOp # "_explicit",
           [Double, PointerType<VolatileType<AtomicDouble>, GlobalAS>, Double, MemoryOrder, MemoryScope]>;
     }
+    let Extension = FuncExtFloatAtomicsFp16LocalMinMax in {
+      def : Builtin<"atomic_fetch_" # ModOp,
+          [Half, PointerType<VolatileType<AtomicHalf>, LocalAS>, Half]>;
+      def : Builtin<"atomic_fetch_" # ModOp # "_explicit",
+          [Half, PointerType<VolatileType<AtomicHalf>, LocalAS>, Half, MemoryOrder]>;
+      def : Builtin<"atomic_fetch_" # ModOp # "_explicit",
+          [Half, PointerType<VolatileType<AtomicHalf>, LocalAS>, Half, MemoryOrder, MemoryScope]>;
+    }
     let Extension = FuncExtFloatAtomicsFp32LocalMinMax in {
       def : Builtin<"atomic_fetch_" # ModOp,
           [Float, PointerType<VolatileType<AtomicFloat>, LocalAS>, Float]>;
       def : Builtin<"atomic_fetch_" # ModOp # "_explicit",
           [Float, PointerType<VolatileType<AtomicFloat>, LocalAS>, Float, MemoryOrder]>;
       def : Builtin<"atomic_fetch_" # ModOp # "_explicit",
           [Float, PointerType<VolatileType<AtomicFloat>, LocalAS>, Float, MemoryOrder, MemoryScope]>;
     }
     let Extension = FuncExtFloatAtomicsFp64LocalMinMax in {
       def : Builtin<"atomic_fetch_" # ModOp,
           [Double, PointerType<VolatileType<AtomicDouble>, LocalAS>, Double]>;
       def : Builtin<"atomic_fetch_" # ModOp # "_explicit",
           [Double, PointerType<VolatileType<AtomicDouble>, LocalAS>, Double, MemoryOrder]>;
       def : Builtin<"atomic_fetch_" # ModOp # "_explicit",
           [Double, PointerType<VolatileType<AtomicDouble>, LocalAS>, Double, MemoryOrder, MemoryScope]>;
     }
+    let Extension = FuncExtFloatAtomicsFp16GenericMinMax in {
+      def : Builtin<"atomic_fetch_" # ModOp,
+          [Half, PointerType<VolatileType<AtomicHalf>, GenericAS>, Half]>;
+      def : Builtin<"atomic_fetch_" # ModOp # "_explicit",
+          [Half, PointerType<VolatileType<AtomicHalf>, GenericAS>, Half, MemoryOrder]>;
+      def : Builtin<"atomic_fetch_" # ModOp # "_explicit",
+          [Half, PointerType<VolatileType<AtomicHalf>, GenericAS>, Half, MemoryOrder, MemoryScope]>;
+    }
     let Extension = FuncExtFloatAtomicsFp32GenericMinMax in {
       def : Builtin<"atomic_fetch_" # ModOp,
           [Float, PointerType<VolatileType<AtomicFloat>, GenericAS>, Float]>;
       def : Builtin<"atomic_fetch_" # ModOp # "_explicit",
           [Float, PointerType<VolatileType<AtomicFloat>, GenericAS>, Float, MemoryOrder]>;
       def : Builtin<"atomic_fetch_" # ModOp # "_explicit",
           [Float, PointerType<VolatileType<AtomicFloat>, GenericAS>, Float, MemoryOrder, MemoryScope]>;
     }

clang/lib/Sema/Sema.cpp

if (getLangOpts().getOpenCLCompatibleVersion() >= 200) {
         addImplicitTypedef("atomic_uintptr_t", AtomicUIntPtrT);
         addImplicitTypedef("atomic_ptrdiff_t", AtomicPtrDiffT);
       };
 
       if (Context.getTypeSize(Context.getSizeType()) == 32) {
         AddPointerSizeDependentTypes();
       }
 
+      if (getOpenCLOptions().isSupported("cl_khr_fp16", getLangOpts())) {
+        auto AtomicHalfT = Context.getAtomicType(Context.HalfTy);
+        addImplicitTypedef("atomic_half", AtomicHalfT);
+      }
+
       std::vector<QualType> Atomic64BitTypes;
       if (getOpenCLOptions().isSupported("cl_khr_int64_base_atomics",
                                          getLangOpts()) &&
           getOpenCLOptions().isSupported("cl_khr_int64_extended_atomics",
                                          getLangOpts())) {
         if (getOpenCLOptions().isSupported("cl_khr_fp64", getLangOpts())) {
           auto AtomicDoubleT = Context.getAtomicType(Context.DoubleTy);
           addImplicitTypedef("atomic_double", AtomicDoubleT);

clang/test/SemaOpenCL/atomic-ops.cl

 
 char i8;
 short i16;
 int i32;
 int8 i64;
 
 atomic_int gn;
 void f(atomic_int *i, const atomic_int *ci,
-       atomic_intptr_t *p, atomic_float *f, atomic_double *d, atomic_half *h, // expected-error {{unknown type name 'atomic_half'}}
+       atomic_intptr_t *p, atomic_float *f, atomic_double *d, atomic_half *h,
        int *I, const int *CI,
        intptr_t *P, float *D, struct S *s1, struct S *s2,
        global atomic_int *i_g, local atomic_int *i_l, private atomic_int *i_p,
        constant atomic_int *i_c) {
   __opencl_atomic_init(I, 5); // expected-error {{address argument to atomic operation must be a pointer to _Atomic type ('__generic int *' invalid)}}
   __opencl_atomic_init(ci, 5); // expected-error {{address argument to atomic operation must be a pointer to non-const _Atomic type ('const __generic atomic_int *' (aka 'const __generic _Atomic(int) *') invalid)}}
 
   __opencl_atomic_load(0); // expected-error {{too few arguments to function call, expected 3, have 1}}