libc/src/__support/macros/config.h

   1 //===-- Portable attributes -------------------------------------*- 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 // This header file defines a set of macros for checking the presence of
   9 // important compiler and platform features. Such macros can be used to
  10 // produce portable code by parameterizing compilation based on the presence or
  11 // lack of a given feature.
  12
  13 #ifndef LLVM_LIBC_SUPPORT_MACROS_CONFIG_H
  14 #define LLVM_LIBC_SUPPORT_MACROS_CONFIG_H
  15
  16 // LIBC_HAS_BUILTIN()
  17 //
  18 // Checks whether the compiler supports a Clang Feature Checking Macro, and if
  19 // so, checks whether it supports the provided builtin function "x" where x
  20 // is one of the functions noted in
  21 // https://clang.llvm.org/docs/LanguageExtensions.html
  22 //
  23 // Note: Use this macro to avoid an extra level of #ifdef __has_builtin check.
  24 // http://releases.llvm.org/3.3/tools/clang/docs/LanguageExtensions.html
  25
  26 // Compiler builtin-detection.
  27 // clang.llvm.org/docs/LanguageExtensions.html#has-builtin
  28 #ifdef __has_builtin
  29 #define LIBC_HAS_BUILTIN(x) __has_builtin(x)
  30 #else
  31 #define LIBC_HAS_BUILTIN(x) 0
  32 #endif
  33
  34 // Compiler feature-detection.
  35 // clang.llvm.org/docs/LanguageExtensions.html#has-feature-and-has-extension
  36 #ifdef __has_feature
  37 #define LIBC_HAS_FEATURE(f) __has_feature(f)
  38 #else
  39 #define LIBC_HAS_FEATURE(f) 0
  40 #endif
  41
  42 #endif // LLVM_LIBC_SUPPORT_MACROS_CONFIG_H