mfbt/Likely.h

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