[libc-commits] [libc] [libc][math][c23] Add f16fmaf C23 math function (PR #95483)

[via libc-commits]

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@@ -74,65 +82,86 @@ template <> LIBC_INLINE float fma<float>(float x, float y, float z) {
 
   return static_cast<float>(bit_sum.get_val());
 }
+#endif // LIBC_TARGET_CPU_HAS_FMA
 
 namespace internal {
 
 // Extract the sticky bits and shift the `mantissa` to the right by
 // `shift_length`.
-LIBC_INLINE bool shift_mantissa(int shift_length, UInt128 &mant) {
-  if (shift_length >= 128) {
+template <typename T>
+LIBC_INLINE cpp::enable_if_t<is_unsigned_integral_or_big_int_v<T>, bool>
+shift_mantissa(int shift_length, T &mant) {
+  if (shift_length >= cpp::numeric_limits<T>::digits) {
     mant = 0;
     return true; // prod_mant is non-zero.
   }
-  UInt128 mask = (UInt128(1) << shift_length) - 1;
+  T mask = (T(1) << shift_length) - 1;
   bool sticky_bits = (mant & mask) != 0;
   mant >>= shift_length;
   return sticky_bits;
 }
 
 } // namespace internal
 
-template <> LIBC_INLINE double fma<double>(double x, double y, double z) {
-  using FPBits = fputil::FPBits<double>;
+template <typename OutType, typename InType>
+LIBC_INLINE cpp::enable_if_t<cpp::is_floating_point_v<OutType> &&
+                                 cpp::is_floating_point_v<InType> &&
+                                 sizeof(OutType) <= sizeof(InType),
+                             OutType>
+fma(InType x, InType y, InType z) {
+  using OutFPBits = fputil::FPBits<OutType>;
+  using OutStorageType = typename OutFPBits::StorageType;
+  using InFPBits = fputil::FPBits<InType>;
+  using InStorageType = typename InFPBits::StorageType;
+
+  constexpr int IN_EXPLICIT_MANT_LEN = InFPBits::FRACTION_LEN + 1;
+  constexpr size_t PROD_LEN = 2 * (IN_EXPLICIT_MANT_LEN);
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lntue wrote:

Parentheses are not needed.

https://github.com/llvm/llvm-project/pull/95483