src/base/compiler_specific.h

// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef BASE_COMPILER_SPECIFIC_H_
#define BASE_COMPILER_SPECIFIC_H_

#include "util/build_config.h"

#if defined(COMPILER_MSVC)

// For _Printf_format_string_.
#include <sal.h>

#else  // Not MSVC

#define _Printf_format_string_

#endif  // COMPILER_MSVC

#if COMPILER_GCC && defined(NDEBUG)
#define ALWAYS_INLINE inline __attribute__((__always_inline__))
#elif COMPILER_MSVC && defined(NDEBUG)
#define ALWAYS_INLINE __forceinline
#else
#define ALWAYS_INLINE inline
#endif

// Annotate a function indicating the caller must examine the return value.
// Use like:
//   int foo() WARN_UNUSED_RESULT;
// To explicitly ignore a result, see |ignore_result()| in base/macros.h.
#undef WARN_UNUSED_RESULT
#if defined(COMPILER_GCC) || defined(__clang__)
#define WARN_UNUSED_RESULT __attribute__((warn_unused_result))
#else
#define WARN_UNUSED_RESULT
#endif

// Tell the compiler a function is using a printf-style format string.
// |format_param| is the one-based index of the format string parameter;
// |dots_param| is the one-based index of the "..." parameter.
// For v*printf functions (which take a va_list), pass 0 for dots_param.
// (This is undocumented but matches what the system C headers do.)
#if defined(COMPILER_GCC) || defined(__clang__)
#define PRINTF_FORMAT(format_param, dots_param) \
  __attribute__((format(printf, format_param, dots_param)))
#else
#define PRINTF_FORMAT(format_param, dots_param)
#endif

// Macro for hinting that an expression is likely to be false.
#if !defined(UNLIKELY)
#if defined(COMPILER_GCC) || defined(__clang__)
#define UNLIKELY(x) __builtin_expect(!!(x), 0)
#else
#define UNLIKELY(x) (x)
#endif  // defined(COMPILER_GCC)
#endif  // !defined(UNLIKELY)

#if !defined(LIKELY)
#if defined(COMPILER_GCC) || defined(__clang__)
#define LIKELY(x) __builtin_expect(!!(x), 1)
#else
#define LIKELY(x) (x)
#endif  // defined(COMPILER_GCC)
#endif  // !defined(LIKELY)

// Macro for telling -Wimplicit-fallthrough that a fallthrough is intentional.
#if defined(__clang__)
#define FALLTHROUGH [[clang::fallthrough]]
#else
#define FALLTHROUGH
#endif

#endif  // BASE_COMPILER_SPECIFIC_H_