mfbt/Likely.h

   1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
   3 /* This Source Code Form is subject to the terms of the Mozilla Public
   4  * License, v. 2.0. If a copy of the MPL was not distributed with this
   5  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   6
   7 /*
   8  * MOZ_LIKELY and MOZ_UNLIKELY macros to hint to the compiler how a
   9  * boolean predicate should be branch-predicted.
  10  */
  11
  12 #ifndef mozilla_Likely_h
  13 #define mozilla_Likely_h
  14
  15 #if defined(__clang__) || defined(__GNUC__)
  16 #  define MOZ_LIKELY(x)   (__builtin_expect(!!(x), 1))
  17 #  define MOZ_UNLIKELY(x) (__builtin_expect(!!(x), 0))
  18 #else
  19 #  define MOZ_LIKELY(x)   (!!(x))
  20 #  define MOZ_UNLIKELY(x) (!!(x))
  21 #endif
  22
  23 #endif /* mozilla_Likely_h */