base/compiler_specific.h

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef BASE_COMPILER_SPECIFIC_H_
   6 #define BASE_COMPILER_SPECIFIC_H_
   7
   8 #include "build/build_config.h"
   9
  10 #if defined(COMPILER_MSVC)
  11
  12 // Macros for suppressing and disabling warnings on MSVC.
  13 //
  14 // Warning numbers are enumerated at:
  15 // http://msdn.microsoft.com/en-us/library/8x5x43k7(VS.80).aspx
  16 //
  17 // The warning pragma:
  18 // http://msdn.microsoft.com/en-us/library/2c8f766e(VS.80).aspx
  19 //
  20 // Using __pragma instead of #pragma inside macros:
  21 // http://msdn.microsoft.com/en-us/library/d9x1s805.aspx
  22
  23 // MSVC_SUPPRESS_WARNING disables warning |n| for the remainder of the line and
  24 // for the next line of the source file.
  25 #define MSVC_SUPPRESS_WARNING(n) __pragma(warning(suppress:n))
  26
  27 // MSVC_PUSH_DISABLE_WARNING pushes |n| onto a stack of warnings to be disabled.
  28 // The warning remains disabled until popped by MSVC_POP_WARNING.
  29 #define MSVC_PUSH_DISABLE_WARNING(n) __pragma(warning(push)) \
  30                                      __pragma(warning(disable:n))
  31
  32 // MSVC_PUSH_WARNING_LEVEL pushes |n| as the global warning level.  The level
  33 // remains in effect until popped by MSVC_POP_WARNING().  Use 0 to disable all
  34 // warnings.
  35 #define MSVC_PUSH_WARNING_LEVEL(n) __pragma(warning(push, n))
  36
  37 // Pop effects of innermost MSVC_PUSH_* macro.
  38 #define MSVC_POP_WARNING() __pragma(warning(pop))
  39
  40 #define MSVC_DISABLE_OPTIMIZE() __pragma(optimize("", off))
  41 #define MSVC_ENABLE_OPTIMIZE() __pragma(optimize("", on))
  42
  43 // Allows exporting a class that inherits from a non-exported base class.
  44 // This uses suppress instead of push/pop because the delimiter after the
  45 // declaration (either "," or "{") has to be placed before the pop macro.
  46 //
  47 // Example usage:
  48 // class EXPORT_API Foo : NON_EXPORTED_BASE(public Bar) {
  49 //
  50 // MSVC Compiler warning C4275:
  51 // non dll-interface class 'Bar' used as base for dll-interface class 'Foo'.
  52 // Note that this is intended to be used only when no access to the base class'
  53 // static data is done through derived classes or inline methods. For more info,
  54 // see http://msdn.microsoft.com/en-us/library/3tdb471s(VS.80).aspx
  55 #define NON_EXPORTED_BASE(code) MSVC_SUPPRESS_WARNING(4275) \
  56                                 code
  57
  58 #else  // Not MSVC
  59
  60 #define MSVC_SUPPRESS_WARNING(n)
  61 #define MSVC_PUSH_DISABLE_WARNING(n)
  62 #define MSVC_PUSH_WARNING_LEVEL(n)
  63 #define MSVC_POP_WARNING()
  64 #define MSVC_DISABLE_OPTIMIZE()
  65 #define MSVC_ENABLE_OPTIMIZE()
  66 #define NON_EXPORTED_BASE(code) code
  67
  68 #endif  // COMPILER_MSVC
  69
  70
  71 // Annotate a variable indicating it's ok if the variable is not used.
  72 // (Typically used to silence a compiler warning when the assignment
  73 // is important for some other reason.)
  74 // Use like:
  75 //   int x ALLOW_UNUSED = ...;
  76 #if defined(COMPILER_GCC)
  77 #define ALLOW_UNUSED __attribute__((unused))
  78 #else
  79 #define ALLOW_UNUSED
  80 #endif
  81
  82 // Annotate a function indicating it should not be inlined.
  83 // Use like:
  84 //   NOINLINE void DoStuff() { ... }
  85 #if defined(COMPILER_GCC)
  86 #define NOINLINE __attribute__((noinline))
  87 #elif defined(COMPILER_MSVC)
  88 #define NOINLINE __declspec(noinline)
  89 #else
  90 #define NOINLINE
  91 #endif
  92
  93 // Specify memory alignment for structs, classes, etc.
  94 // Use like:
  95 //   class ALIGNAS(16) MyClass { ... }
  96 //   ALIGNAS(16) int array[4];
  97 #if defined(COMPILER_MSVC)
  98 #define ALIGNAS(byte_alignment) __declspec(align(byte_alignment))
  99 #elif defined(COMPILER_GCC)
 100 #define ALIGNAS(byte_alignment) __attribute__((aligned(byte_alignment)))
 101 #endif
 102
 103 // Return the byte alignment of the given type (available at compile time).  Use
 104 // sizeof(type) prior to checking __alignof to workaround Visual C++ bug:
 105 // http://goo.gl/isH0C
 106 // Use like:
 107 //   ALIGNOF(int32)  // this would be 4
 108 #if defined(COMPILER_MSVC)
 109 #define ALIGNOF(type) (sizeof(type) - sizeof(type) + __alignof(type))
 110 #elif defined(COMPILER_GCC)
 111 #define ALIGNOF(type) __alignof__(type)
 112 #endif
 113
 114 // Annotate a virtual method indicating it must be overriding a virtual
 115 // method in the parent class.
 116 // Use like:
 117 //   virtual void foo() OVERRIDE;
 118 #if defined(COMPILER_MSVC)
 119 #define OVERRIDE override
 120 #elif defined(__clang__)
 121 #define OVERRIDE override
 122 #else
 123 #define OVERRIDE
 124 #endif
 125
 126 // Annotate a virtual method indicating that subclasses must not override it,
 127 // or annotate a class to indicate that it cannot be subclassed.
 128 // Use like:
 129 //   virtual void foo() FINAL;
 130 //   class B FINAL : public A {};
 131 #if defined(COMPILER_MSVC)
 132 // TODO(jered): Change this to "final" when chromium no longer uses MSVC 2010.
 133 #define FINAL sealed
 134 #elif defined(__clang__)
 135 #define FINAL final
 136 #else
 137 #define FINAL
 138 #endif
 139
 140 // Annotate a function indicating the caller must examine the return value.
 141 // Use like:
 142 //   int foo() WARN_UNUSED_RESULT;
 143 // To explicitly ignore a result, see |ignore_result()| in <base/basictypes.h>.
 144 #if defined(COMPILER_GCC)
 145 #define WARN_UNUSED_RESULT __attribute__((warn_unused_result))
 146 #else
 147 #define WARN_UNUSED_RESULT
 148 #endif
 149
 150 // Tell the compiler a function is using a printf-style format string.
 151 // |format_param| is the one-based index of the format string parameter;
 152 // |dots_param| is the one-based index of the "..." parameter.
 153 // For v*printf functions (which take a va_list), pass 0 for dots_param.
 154 // (This is undocumented but matches what the system C headers do.)
 155 #if defined(COMPILER_GCC)
 156 #define PRINTF_FORMAT(format_param, dots_param) \
 157     __attribute__((format(printf, format_param, dots_param)))
 158 #else
 159 #define PRINTF_FORMAT(format_param, dots_param)
 160 #endif
 161
 162 // WPRINTF_FORMAT is the same, but for wide format strings.
 163 // This doesn't appear to yet be implemented in any compiler.
 164 // See http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38308 .
 165 #define WPRINTF_FORMAT(format_param, dots_param)
 166 // If available, it would look like:
 167 //   __attribute__((format(wprintf, format_param, dots_param)))
 168
 169
 170 // MemorySanitizer annotations.
 171 #ifdef MEMORY_SANITIZER
 172 extern "C" {
 173 void __msan_unpoison(const void *p, unsigned long s);
 174 }  // extern "C"
 175
 176 // Mark a memory region fully initialized.
 177 // Use this to annotate code that deliberately reads uninitialized data, for
 178 // example a GC scavenging root set pointers from the stack.
 179 #define MSAN_UNPOISON(p, s)  __msan_unpoison(p, s)
 180 #else  // MEMORY_SANITIZER
 181 #define MSAN_UNPOISON(p, s)
 182 #endif  // MEMORY_SANITIZER
 183
 184 #endif  // BASE_COMPILER_SPECIFIC_H_