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

[via libc-commits]

================
@@ -19,85 +18,115 @@
 
 namespace mpfr = LIBC_NAMESPACE::testing::mpfr;
 
-template <typename T>
+template <typename OutType, typename InType = OutType>
 class FmaTestTemplate : public LIBC_NAMESPACE::testing::FEnvSafeTest {
-private:
-  using Func = T (*)(T, T, T);
-  using FPBits = LIBC_NAMESPACE::fputil::FPBits<T>;
-  using StorageType = typename FPBits::StorageType;
-
-  const T min_subnormal = FPBits::min_subnormal(Sign::POS).get_val();
-  const T min_normal = FPBits::min_normal(Sign::POS).get_val();
-  const T max_normal = FPBits::max_normal(Sign::POS).get_val();
-  const T inf = FPBits::inf(Sign::POS).get_val();
-  const T neg_inf = FPBits::inf(Sign::NEG).get_val();
-  const T zero = FPBits::zero(Sign::POS).get_val();
-  const T neg_zero = FPBits::zero(Sign::NEG).get_val();
-  const T nan = FPBits::quiet_nan().get_val();
-
-  static constexpr StorageType MAX_NORMAL = FPBits::max_normal().uintval();
-  static constexpr StorageType MIN_NORMAL = FPBits::min_normal().uintval();
-  static constexpr StorageType MAX_SUBNORMAL =
-      FPBits::max_subnormal().uintval();
-  static constexpr StorageType MIN_SUBNORMAL =
-      FPBits::min_subnormal().uintval();
-
-  StorageType get_random_bit_pattern() {
-    StorageType bits{0};
-    for (StorageType i = 0; i < sizeof(StorageType) / 2; ++i) {
+
+  struct OutConstants {
+    DECLARE_SPECIAL_CONSTANTS(OutType)
+  };
+
+  struct InConstants {
+    DECLARE_SPECIAL_CONSTANTS(InType)
+  };
+
+  using OutFPBits = typename OutConstants::FPBits;
+  using OutStorageType = typename OutConstants::StorageType;
+  using InFPBits = typename InConstants::FPBits;
+  using InStorageType = typename InConstants::StorageType;
+
+  static constexpr OutStorageType OUT_MIN_NORMAL_U =
+      OutFPBits::min_normal().uintval();
+  static constexpr InStorageType IN_MAX_NORMAL_U =
+      InFPBits::max_normal().uintval();
+  static constexpr InStorageType IN_MIN_NORMAL_U =
+      InFPBits::min_normal().uintval();
+  static constexpr InStorageType IN_MAX_SUBNORMAL_U =
+      InFPBits::max_subnormal().uintval();
+  static constexpr InStorageType IN_MIN_SUBNORMAL_U =
+      InFPBits::min_subnormal().uintval();
+
+  OutConstants out;
+  InConstants in;
+
+  InStorageType get_random_bit_pattern() {
+    InStorageType bits{0};
+    for (InStorageType i = 0; i < sizeof(InStorageType) / 2; ++i) {
       bits = (bits << 2) + static_cast<uint16_t>(LIBC_NAMESPACE::rand());
     }
     return bits;
   }
 
 public:
-  void test_special_numbers(Func func) {
-    EXPECT_FP_EQ(func(zero, zero, zero), zero);
-    EXPECT_FP_EQ(func(zero, neg_zero, neg_zero), neg_zero);
-    EXPECT_FP_EQ(func(inf, inf, zero), inf);
-    EXPECT_FP_EQ(func(neg_inf, inf, neg_inf), neg_inf);
-    EXPECT_FP_EQ(func(inf, zero, zero), nan);
-    EXPECT_FP_EQ(func(inf, neg_inf, inf), nan);
-    EXPECT_FP_EQ(func(nan, zero, inf), nan);
-    EXPECT_FP_EQ(func(inf, neg_inf, nan), nan);
+  using FmaFunc = OutType (*)(InType, InType, InType);
+
+  void test_special_numbers(FmaFunc func) {
+    EXPECT_FP_EQ(out.zero, func(in.zero, in.zero, in.zero));
+    EXPECT_FP_EQ(out.neg_zero, func(in.zero, in.neg_zero, in.neg_zero));
+    EXPECT_FP_EQ(out.inf, func(in.inf, in.inf, in.zero));
+    EXPECT_FP_EQ(out.neg_inf, func(in.neg_inf, in.inf, in.neg_inf));
+    EXPECT_FP_EQ(out.aNaN, func(in.inf, in.zero, in.zero));
+    EXPECT_FP_EQ(out.aNaN, func(in.inf, in.neg_inf, in.inf));
+    EXPECT_FP_EQ(out.aNaN, func(in.aNaN, in.zero, in.inf));
+    EXPECT_FP_EQ(out.aNaN, func(in.inf, in.neg_inf, in.aNaN));
 
     // Test underflow rounding up.
-    EXPECT_FP_EQ(func(T(0.5), min_subnormal, min_subnormal),
-                 FPBits(StorageType(2)).get_val());
+    EXPECT_FP_EQ(OutFPBits(OutStorageType(2)).get_val(),
+                 func(OutType(0.5), out.min_denormal, out.min_denormal));
+
+    if constexpr (sizeof(OutType) < sizeof(InType)) {
+      EXPECT_FP_EQ(out.zero,
+                   func(InType(0.5), in.min_denormal, in.min_denormal));
+    }
     // Test underflow rounding down.
-    T v = FPBits(MIN_NORMAL + StorageType(1)).get_val();
-    EXPECT_FP_EQ(func(T(1) / T(MIN_NORMAL << 1), v, min_normal), v);
+    OutType v = OutFPBits(static_cast<OutStorageType>(OUT_MIN_NORMAL_U +
+                                                      OutStorageType(1)))
+                    .get_val();
+    EXPECT_FP_EQ(v, func(OutType(1) / OutType(OUT_MIN_NORMAL_U << 1), v,
+                         out.min_normal));
+
+    if constexpr (sizeof(OutType) < sizeof(InType)) {
+      InType v = InFPBits(static_cast<InStorageType>(IN_MIN_NORMAL_U +
+                                                     InStorageType(1)))
+                     .get_val();
+      EXPECT_FP_EQ(
+          out.min_normal,
+          func(InType(1) / InType(IN_MIN_NORMAL_U << 1), v, out.min_normal));
+    }
     // Test overflow.
-    T z = max_normal;
-    EXPECT_FP_EQ(func(T(1.75), z, -z), T(0.75) * z);
+    OutType z = out.max_normal;
+    EXPECT_FP_EQ(OutType(0.75) * z, func(InType(1.75), z, -z));
----------------
overmighty wrote:

By the way, the whole `test_special_numbers` function is copied from the smoke test. Should we remove it from the MPFR unit test?

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