[libc-commits] [libc] [libc][math][c++23] Add bfloat16 support in LLVM libc (PR #144463)

[via libc-commits]

================
@@ -0,0 +1,60 @@
+//===-- Definition of bfloat16 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_BFLOAT16_H
+#define LLVM_LIBC_SRC___SUPPORT_FPUTIL_BFLOAT16_H
+
+#include "src/__support/CPP/bit.h"
+#include "src/__support/CPP/type_traits.h"
+#include "src/__support/FPUtil/cast.h"
+#include "src/__support/macros/config.h"
+#include "src/__support/macros/properties/types.h"
+
+#include <stdint.h>
+
+namespace LIBC_NAMESPACE_DECL {
+struct BFloat16 {
+  uint16_t bits;
+
+  BFloat16() = default;
+
+  constexpr explicit BFloat16(uint16_t bits) : bits(bits) {}
+
+  template <typename T> constexpr explicit BFloat16(T value) {
+    if constexpr (cpp::is_floating_point_v<T>) {
+      bits = fputil::cast<bfloat16>(value).bits;
+    } else if constexpr (cpp::is_integral_v<T>) {
+      Sign sign = Sign::POS;
+
+      if constexpr (cpp::is_signed_v<T>) {
+        if (value < 0) {
+          sign = Sign::NEG;
+          value = -value;
+        }
+      }
+
+      bits = fputil::DyadicFloat<
+                 cpp::numeric_limits<cpp::make_unsigned_t<T>>::digits>(sign, 0,
+                                                                       value)
+                 .template as<bfloat16, /*ShouldSignalExceptions=*/true>()
+                 .bits;
----------------
overmighty wrote:

Introducing a variable for the `DyadicFloat` should play better with Clang-Format.

https://github.com/llvm/llvm-project/pull/144463