make bit_cast a function

src/include/migraphx/migraphx_hip_f8_impl.hpp

@@ -41,6 +41,18 @@ struct conditional<false, T, F>
 {
     using type = F;
 };
+
+template <typename To, typename From>
+inline constexpr To bit_cast(From fr) noexcept
+{
+    static_assert(sizeof(To) == sizeof(From));
+#if defined(__GNUC__) and !defined(__clang__)
+    To x = CONST_FOLD(*reinterpret_cast<To*>(&fr));
+#else
+    To x = __builtin_bit_cast(To, fr);
+#endif
+    return x;
+}
 } // namespace detail
 
 // #ifdef __HIP_PLATFORM_HCC__
@@ -58,17 +70,10 @@ MIGRAPHX_HIP_HOST_DEVICE constexpr uint8_t cast_to_f8(T _x, bool stoch, uint32_t
     const int mfmt = (sizeof(T) == 4) ? 23 : 10;
     typename detail::conditional<sizeof(T) == 2, uint16_t, uint32_t>::type x;
 
-#if defined(__GNUC__) and !defined(__clang__)
     if constexpr(sizeof(T) == 4)
-        x = CONST_FOLD(*reinterpret_cast<uint32_t*>(&_x));
+        x = detail::bit_cast<uint32_t>(_x);
     else
-        x = CONST_FOLD(*reinterpret_cast<uint16_t*>(&_x));
-#else
-    if constexpr(sizeof(T) == 4)
-        x = __builtin_bit_cast(uint32_t, _x);
-    else
-        x = __builtin_bit_cast(uint16_t, _x);
-#endif
+        x = detail::bit_cast<uint16_t>(_x);
 
     uint32_t head, mantissa;
     int exponent, bias;
@@ -246,18 +251,11 @@ MIGRAPHX_HIP_HOST_DEVICE constexpr T cast_from_f8(uint8_t x)
     uint32_t ifNegInf = 0xFF800000;
     uint32_t ifNaN    = 0x7F800001;
     uint32_t ifNeg0   = 0x80000000;
-#if defined(__GNUC__) and !defined(__clang__)
-    fInf    = CONST_FOLD(*(reinterpret_cast<float*>(&ifInf)));
-    fNegInf = CONST_FOLD(*(reinterpret_cast<float*>(&ifNegInf)));
-    fNaN    = CONST_FOLD(*(reinterpret_cast<float*>(&ifNaN)));
-    fNeg0   = CONST_FOLD(*(reinterpret_cast<float*>(&ifNeg0)));
-#else
     // TODO: need to change T for half but right now it would never be called with half
-    fInf    = __builtin_bit_cast(float, ifInf);
-    fNegInf = __builtin_bit_cast(float, ifNegInf);
-    fNaN    = __builtin_bit_cast(float, ifNaN);
-    fNeg0   = __builtin_bit_cast(float, ifNeg0);
-#endif
+    fInf    = detail::bit_cast<float>(ifInf);
+    fNegInf = detail::bit_cast<float>(ifNegInf);
+    fNaN    = detail::bit_cast<float>(ifNaN);
+    fNeg0   = detail::bit_cast<float>(ifNeg0);
 
     if(x == 0)
         return 0;
@@ -305,11 +303,7 @@ MIGRAPHX_HIP_HOST_DEVICE constexpr T cast_from_f8(uint8_t x)
         retval = (sign << 15) | (exponent << 10) | mantissa;
     else
         retval = (sign << 31) | (exponent << 23) | mantissa;
-#if defined(__GNUC__) and !defined(__clang__)
-    return CONST_FOLD(*reinterpret_cast<T*>(&retval));
-#else
-    return __builtin_bit_cast(T, retval);
-#endif
+    return detail::bit_cast<T>(retval);
 }
 
 } // namespace migraphx_hip_f8_impl