[libc-commits] [libc] [libc][math][c23] Add hypotf16 function (PR #131991)

[via libc-commits]

================
@@ -0,0 +1,86 @@
+//===-- Implementation of hypotf16 function -------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "src/math/hypotf16.h"
+#include "src/__support/FPUtil/FEnvImpl.h"
+#include "src/__support/FPUtil/FPBits.h"
+#include "src/__support/FPUtil/cast.h"
+#include "src/__support/FPUtil/multiply_add.h"
+#include "src/__support/FPUtil/sqrt.h"
+#include "src/__support/common.h"
+#include "src/__support/macros/optimization.h"
+#include "src/__support/macros/properties/types.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+LLVM_LIBC_FUNCTION(float16, hypotf16, (float16 x, float16 y)) {
+  using FloatBits = fputil::FPBits<float>;
+  using FPBits = fputil::FPBits<float16>;
+
+  FPBits x_abs = FPBits(x).abs();
+  FPBits y_abs = FPBits(y).abs();
+
+  bool x_abs_larger = x_abs.uintval() >= y_abs.uintval();
+
+  FPBits a_bits = x_abs_larger ? x_abs : y_abs;
+  FPBits b_bits = x_abs_larger ? y_abs : x_abs;
+
+  uint16_t a_u = a_bits.uintval();
+  uint16_t b_u = b_bits.uintval();
+
+  // Note: replacing `a_u >= FPBits::EXP_MASK` with `a_bits.is_inf_or_nan()`
+  // generates extra exponent bit masking instructions on x86-64.
+  if (LIBC_UNLIKELY(a_u >= FPBits::EXP_MASK)) {
+    // x or y is inf or nan
+    if (a_bits.is_signaling_nan() || b_bits.is_signaling_nan()) {
+      fputil::raise_except_if_required(FE_INVALID);
+      return FPBits::quiet_nan().get_val();
+    }
+    if (a_bits.is_inf() || b_bits.is_inf())
+      return FPBits::inf().get_val();
+    return a_bits.get_val();
+  }
+
+  if (LIBC_UNLIKELY(a_u - b_u >=
+                    static_cast<uint16_t>((FPBits::FRACTION_LEN + 2)
+                                          << FPBits::FRACTION_LEN)))
+    return x_abs.get_val() + y_abs.get_val();
+
+  float ad = fputil::cast<float>(a_bits.get_val());
+  float bd = fputil::cast<float>(b_bits.get_val());
----------------
lntue wrote:

nit: change this to `af`, `bf` instead, to signify that they are `float` instead of `double`

https://github.com/llvm/llvm-project/pull/131991