libc/src/threads/linux/Futex.h

   1 //===-- Linux futex related definitions -------------------------*- C++ -*-===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8
   9 #ifndef LLVM_LIBC_SRC_THREADS_LINUX_FUTEX_H
  10 #define LLVM_LIBC_SRC_THREADS_LINUX_FUTEX_H
  11
  12 #include "src/__support/macros/properties/architectures.h" // Architecture macros
  13
  14 namespace __llvm_libc {
  15
  16 #if (defined(LIBC_TARGET_ARCH_IS_AARCH64) ||                                   \
  17      defined(LIBC_TARGET_ARCH_IS_X86_64))
  18 // The futex data has to be exactly 4 bytes long. However, we use a uint type
  19 // here as we do not want to use `uint32_t` type to match the public definitions
  20 // of types which include a field for a futex word. With public definitions, we
  21 // cannot include <stdint.h> so we stick to the `unsigned int` type for x86_64
  22 // and aarch64
  23 using FutexWordType = unsigned int;
  24 static_assert(sizeof(FutexWordType) == 4,
  25               "Unexpected size of unsigned int type.");
  26 #else
  27 #error "Futex word base type not defined for the target architecture."
  28 #endif
  29
  30 } // namespace __llvm_libc
  31
  32 #endif // LLVM_LIBC_SRC_THREADS_LINUX_FUTEX_H