Use native support for atomic FADD when address is in LDS (#1591)

hipamd/include/hip/hcc_detail/hip_atomic.h

@@ -55,7 +55,7 @@ unsigned long long atomicAdd(
 }
 __device__
 inline
-float atomicAdd(float* address, float val)
+float atomicAdd_impl(float* address, float val)
 {
     unsigned int* uaddr{reinterpret_cast<unsigned int*>(address)};
     unsigned int r{__atomic_load_n(uaddr, __ATOMIC_RELAXED)};
@@ -73,6 +73,37 @@ float atomicAdd(float* address, float val)
 
     return __uint_as_float(r);
 }
+#if !__has_builtin(__builtin_amdgcn_is_shared)
+    __device__
+    inline
+    bool __builtin_amdgcn_is_shared(
+        const __attribute__((address_space(0))) void* ptr) noexcept
+    {
+        #if defined(__HIP_DEVICE_COMPILE__)
+            const unsigned int gp = reinterpret_cast<unsigned long long>(ptr);
+
+            return gp ==
+                (__builtin_amdgcn_s_getreg((15 << 11) | (16 << 6) | 15) << 16);
+        #else
+            return false;
+        #endif
+    }
+#endif
+__device__
+inline
+float atomicAdd(float* address, float val)
+{
+    using GP = const __attribute__((address_space(0))) void*;
+    using LP = __attribute__((address_space(3))) float*;
+
+    #if __HIP_ARCH_GFX900__ || __HIP_ARCH_GFX906__ || __HIP_ARCH_GFX908__
+        if (__builtin_amdgcn_is_shared((GP) address)) {
+            return __builtin_amdgcn_ds_faddf((LP) address, val, 0, 0, false);
+        }
+    #endif
+
+    return atomicAdd_impl(address, val);
+}
 __device__
 inline
 double atomicAdd(double* address, double val)