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// The C++ standard requires that static const members have an out-of-class 72// definition (in a single compilation unit), but MSVC chokes on this (when 73// language extensions, which are required, are enabled). (You're only likely to 74// notice the need for a definition if you take the address of the member or, 75// more commonly, pass it to a function that takes it as a reference argument -- 76// probably an STL function.) This macro makes MSVC do the right thing. See 77// http://msdn.microsoft.com/en-us/library/34h23df8(v=vs.100).aspx for more 78// information. Use like: 79// 80// In .h file: 81// struct Foo { 82// static const int kBar = 5; 83// }; 84// 85// In .cc file: 86// STATIC_CONST_MEMBER_DEFINITION const int Foo::kBar; 87#if defined(COMPILER_MSVC) 88#define STATIC_CONST_MEMBER_DEFINITION __declspec(selectany) 89#else 90#define STATIC_CONST_MEMBER_DEFINITION 91#endif 92 93// Annotate a variable indicating it's ok if the variable is not used. 94// (Typically used to silence a compiler warning when the assignment 95// is important for some other reason.) 96// Use like: 97// int x ALLOW_UNUSED = ...; 98#if defined(COMPILER_GCC) 99#define ALLOW_UNUSED __attribute__((unused)) 100#else 101#define ALLOW_UNUSED 102#endif 103 104// Annotate a function indicating it should not be inlined. 105// Use like: 106// NOINLINE void DoStuff() { ... } 107#if defined(COMPILER_GCC) 108#define NOINLINE __attribute__((noinline)) 109#elif defined(COMPILER_MSVC) 110#define NOINLINE __declspec(noinline) 111#else 112#define NOINLINE 113#endif 114 115// Specify memory alignment for structs, classes, etc. 116// Use like: 117// class ALIGNAS(16) MyClass { ... } 118// ALIGNAS(16) int array[4]; 119#if defined(COMPILER_MSVC) 120#define ALIGNAS(byte_alignment) __declspec(align(byte_alignment)) 121#elif defined(COMPILER_GCC) 122#define ALIGNAS(byte_alignment) __attribute__((aligned(byte_alignment))) 123#endif 124 125// Return the byte alignment of the given type (available at compile time). Use 126// sizeof(type) prior to checking __alignof to workaround Visual C++ bug: 127// http://goo.gl/isH0C 128// Use like: 129// ALIGNOF(int32) // this would be 4 130#if defined(COMPILER_MSVC) 131#define ALIGNOF(type) (sizeof(type) - sizeof(type) + __alignof(type)) 132#elif defined(COMPILER_GCC) 133#define ALIGNOF(type) __alignof__(type) 134#endif 135 136// Annotate a virtual method indicating it must be overriding a virtual 137// method in the parent class. 138// Use like: 139// virtual void foo() OVERRIDE; 140#define OVERRIDE override 141 142// Annotate a virtual method indicating that subclasses must not override it, 143// or annotate a class to indicate that it cannot be subclassed. 144// Use like: 145// virtual void foo() FINAL; 146// class B FINAL : public A {}; 147#define FINAL final 148 149// Annotate a function indicating the caller must examine the return value. 150// Use like: 151// int foo() WARN_UNUSED_RESULT; 152// To explicitly ignore a result, see |ignore_result()| in <base/basictypes.h>. 153#if defined(COMPILER_GCC) 154#define WARN_UNUSED_RESULT __attribute__((warn_unused_result)) 155#else 156#define WARN_UNUSED_RESULT 157#endif 158 159// Tell the compiler a function is using a printf-style format string. 160// |format_param| is the one-based index of the format string parameter; 161// |dots_param| is the one-based index of the "..." parameter. 162// For v*printf functions (which take a va_list), pass 0 for dots_param. 163// (This is undocumented but matches what the system C headers do.) 164#if defined(COMPILER_GCC) 165#define PRINTF_FORMAT(format_param, dots_param) \ 166 __attribute__((format(printf, format_param, dots_param))) 167#else 168#define PRINTF_FORMAT(format_param, dots_param) 169#endif 170 171// WPRINTF_FORMAT is the same, but for wide format strings. 172// This doesn't appear to yet be implemented in any compiler. 173// See http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38308 . 174#define WPRINTF_FORMAT(format_param, dots_param) 175// If available, it would look like: 176// __attribute__((format(wprintf, format_param, dots_param))) 177 178// MemorySanitizer annotations. 179#if defined(MEMORY_SANITIZER) && !defined(OS_NACL) 180#include <sanitizer/msan_interface.h> 181 182// Mark a memory region fully initialized. 183// Use this to annotate code that deliberately reads uninitialized data, for 184// example a GC scavenging root set pointers from the stack. 185#define MSAN_UNPOISON(p, s) __msan_unpoison(p, s) 186#else // MEMORY_SANITIZER 187#define MSAN_UNPOISON(p, s) 188#endif // MEMORY_SANITIZER 189 190// Macro useful for writing cross-platform function pointers. 191#if !defined(CDECL) 192#if defined(OS_WIN) 193#define CDECL __cdecl 194#else // defined(OS_WIN) 195#define CDECL 196#endif // defined(OS_WIN) 197#endif // !defined(CDECL) 198 199// Macro for hinting that an expression is likely to be false. 200#if !defined(UNLIKELY) 201#if defined(COMPILER_GCC) 202#define UNLIKELY(x) __builtin_expect(!!(x), 0) 203#else 204#define UNLIKELY(x) (x) 205#endif // defined(COMPILER_GCC) 206#endif // !defined(UNLIKELY) 207 208#endif // BASE_COMPILER_SPECIFIC_H_ 209