[libc-commits] [libc] [libc] Float80 Emulation in LLVM libc (PR #214447)

[via libc-commits]

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@@ -0,0 +1,108 @@
+//===-- Definition for Float80 data type -----------------------*- C++ -*-===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIBC_SRC___SUPPORT_FPUTIL_FLOAT80_H
+#define LLVM_LIBC_SRC___SUPPORT_FPUTIL_FLOAT80_H
+
+#include "hdr/stdint_proxy.h"
+#include "src/__support/CPP/type_traits.h"
+#include "src/__support/FPUtil/cast.h"
+#include "src/__support/FPUtil/comparison_operations.h"
+#include "src/__support/FPUtil/dyadic_float.h"
+#include "src/__support/FPUtil/generic/add_sub.h"
+#include "src/__support/FPUtil/generic/div.h"
+#include "src/__support/FPUtil/generic/mul.h"
+#include "src/__support/macros/attributes.h"
+#include "src/__support/macros/config.h"
+#include "src/__support/uint128.h"
+
+namespace LIBC_NAMESPACE_DECL {
+namespace fputil {
+
+struct Float80 {
+  UInt128 bits;
+
+  LIBC_INLINE Float80() = default;
+  LIBC_INLINE constexpr Float80(const Float80 &) = default;
+  LIBC_INLINE constexpr Float80(Float80 &&) = default;
+  LIBC_INLINE constexpr Float80 &operator=(const Float80 &) = default;
+  LIBC_INLINE constexpr Float80 &operator=(Float80 &&) = default;
+
+  // Floating point type and integer type
+  template <typename T>
+  LIBC_INLINE constexpr explicit Float80(T value) : bits(0U) {
+    if constexpr (cpp::is_floating_point_v<T>) {
+      bits = fputil::cast<Float80>(value).bits;
+    } else if constexpr (cpp::is_integral_v<T>) {
+      Sign sign = Sign::POS;
+      auto unsigned_value = static_cast<cpp::make_unsigned_t<T>>(value);
+
+      if constexpr (cpp::is_signed_v<T>) {
+        if (value < 0) {
+          sign = Sign::NEG;
+          unsigned_value = -unsigned_value;
+        }
+      }
+
+      fputil::DyadicFloat<FPBits<Float80>::STORAGE_LEN> xd(sign, 0,
+                                                           unsigned_value);
+      bits = xd.template as<Float80, /*ShouldSignalExceptions=*/true>().bits;
+
+    } else if constexpr (cpp::is_convertible_v<T, Float80>) {
+      bits = value.operator Float80().bits;
+    } else {
+      bits = fputil::cast<Float80>(static_cast<float>(value)).bits;
+    }
+  }
+
+  template <typename T, cpp::enable_if_t<cpp::is_floating_point_v<T> &&
+                                             !cpp::is_same_v<T, Float80>,
+                                         int> = 0>
+  LIBC_INLINE LIBC_CONSTEXPR_DEFAULT operator T() const {
+    return fputil::cast<T>(*this);
+  }
+
+  template <typename T, cpp::enable_if_t<cpp::is_integral_v<T>, int> = 0>
+  LIBC_INLINE constexpr explicit operator T() const {
+    constexpr T MIN_T = cpp::numeric_limits<T>::min();
+    constexpr T MAX_T = cpp::numeric_limits<T>::max();
+    FPBits<Float80> x_bits(*this);
+    // Raise FE_INVALID for inf and NaN
+    if (x_bits.is_inf_or_nan()) {
+      raise_except_if_required(FE_INVALID);
+      return x_bits.is_neg() ? MIN_T : MAX_T;
+    }
+    int exponent = x_bits.get_explicit_exponent();
+    constexpr int EXPONENT_LIMIT = cpp::numeric_limits<T>::digits;
+    if (exponent > EXPONENT_LIMIT) {
+      raise_except_if_required(FE_INVALID);
+      return x_bits.is_neg() ? MIN_T : MAX_T;
+    } else if (exponent == EXPONENT_LIMIT) {
+      if (x_bits.is_pos() || x_bits.get_mantissa() != 0) {
+        raise_except_if_required(FE_INVALID);
+        return x_bits.is_neg() ? MIN_T : MAX_T;
+      }
+    }
+
+    int x_bits_exp = exponent - FPBits<Float80>::FRACTION_LEN;
+    // sign * 2^(exp-bias) * mantissa
+    DyadicFloat<FPBits<Float80>::STORAGE_LEN> xd(
+        x_bits.sign(), x_bits_exp, x_bits.get_explicit_mantissa());
+    return static_cast<T>(xd.as_mantissa_type());
+  }
+};
+
+static_assert(LIBC_NAMESPACE::cpp::is_trivially_constructible<
+              LIBC_NAMESPACE::fputil::Float80>::value);
+static_assert(LIBC_NAMESPACE::cpp::is_trivially_copyable<
+              LIBC_NAMESPACE::fputil::Float80>::value);
+
----------------
Sukumarsawant wrote:

Can be removed

https://github.com/llvm/llvm-project/pull/214447