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(ANDROID) 11// Prefer Android's libbase definitions to our own. 12#include <android-base/macros.h> 13#endif // defined(ANDROID) 14 15#if defined(COMPILER_MSVC) 16 17// For _Printf_format_string_. 18#include <sal.h> 19 20// Macros for suppressing and disabling warnings on MSVC. 21// 22// Warning numbers are enumerated at: 23// http://msdn.microsoft.com/en-us/library/8x5x43k7(VS.80).aspx 24// 25// The warning pragma: 26// http://msdn.microsoft.com/en-us/library/2c8f766e(VS.80).aspx 27// 28// Using __pragma instead of #pragma inside macros: 29// http://msdn.microsoft.com/en-us/library/d9x1s805.aspx 30 31// MSVC_SUPPRESS_WARNING disables warning |n| for the remainder of the line and 32// for the next line of the source file. 33#define MSVC_SUPPRESS_WARNING(n) __pragma(warning(suppress:n)) 34 35// MSVC_PUSH_DISABLE_WARNING pushes |n| onto a stack of warnings to be disabled. 36// The warning remains disabled until popped by MSVC_POP_WARNING. 37#define MSVC_PUSH_DISABLE_WARNING(n) __pragma(warning(push)) \ 38 __pragma(warning(disable:n)) 39 40// MSVC_PUSH_WARNING_LEVEL pushes |n| as the global warning level. The level 41// remains in effect until popped by MSVC_POP_WARNING(). Use 0 to disable all 42// warnings. 43#define MSVC_PUSH_WARNING_LEVEL(n) __pragma(warning(push, n)) 44 45// Pop effects of innermost MSVC_PUSH_* macro. 46#define MSVC_POP_WARNING() __pragma(warning(pop)) 47 48#define MSVC_DISABLE_OPTIMIZE() __pragma(optimize("", off)) 49#define MSVC_ENABLE_OPTIMIZE() __pragma(optimize("", on)) 50 51// Allows exporting a class that inherits from a non-exported base class. 52// This uses suppress instead of push/pop because the delimiter after the 53// declaration (either "," or "{") has to be placed before the pop macro. 54// 55// Example usage: 56// class EXPORT_API Foo : NON_EXPORTED_BASE(public Bar) { 57// 58// MSVC Compiler warning C4275: 59// non dll-interface class 'Bar' used as base for dll-interface class 'Foo'. 60// Note that this is intended to be used only when no access to the base class' 61// static data is done through derived classes or inline methods. For more info, 62// see http://msdn.microsoft.com/en-us/library/3tdb471s(VS.80).aspx 63#define NON_EXPORTED_BASE(code) MSVC_SUPPRESS_WARNING(4275) \ 64 code 65 66#else // Not MSVC 67 68#define _Printf_format_string_ 69#define MSVC_SUPPRESS_WARNING(n) 70#define MSVC_PUSH_DISABLE_WARNING(n) 71#define MSVC_PUSH_WARNING_LEVEL(n) 72#define MSVC_POP_WARNING() 73#define MSVC_DISABLE_OPTIMIZE() 74#define MSVC_ENABLE_OPTIMIZE() 75#define NON_EXPORTED_BASE(code) code 76 77#endif // COMPILER_MSVC 78 79 80// Annotate a variable indicating it's ok if the variable is not used. 81// (Typically used to silence a compiler warning when the assignment 82// is important for some other reason.) 83// Use like: 84// int x = ...; 85// ALLOW_UNUSED_LOCAL(x); 86#define ALLOW_UNUSED_LOCAL(x) false ? (void)x : (void)0 87 88// Annotate a typedef or function indicating it's ok if it's not used. 89// Use like: 90// typedef Foo Bar ALLOW_UNUSED_TYPE; 91#if defined(COMPILER_GCC) || defined(__clang__) 92#define ALLOW_UNUSED_TYPE __attribute__((unused)) 93#else 94#define ALLOW_UNUSED_TYPE 95#endif 96 97// Annotate a function indicating it should not be inlined. 98// Use like: 99// NOINLINE void DoStuff() { ... } 100#if defined(COMPILER_GCC) 101#define NOINLINE __attribute__((noinline)) 102#elif defined(COMPILER_MSVC) 103#define NOINLINE __declspec(noinline) 104#else 105#define NOINLINE 106#endif 107 108#if COMPILER_GCC && defined(NDEBUG) 109#define ALWAYS_INLINE inline __attribute__((__always_inline__)) 110#elif COMPILER_MSVC && defined(NDEBUG) 111#define ALWAYS_INLINE __forceinline 112#else 113#define ALWAYS_INLINE inline 114#endif 115 116// Specify memory alignment for structs, classes, etc. 117// Use like: 118// class ALIGNAS(16) MyClass { ... } 119// ALIGNAS(16) int array[4]; 120#if defined(COMPILER_MSVC) 121#define ALIGNAS(byte_alignment) __declspec(align(byte_alignment)) 122#elif defined(COMPILER_GCC) 123#define ALIGNAS(byte_alignment) __attribute__((aligned(byte_alignment))) 124#endif 125 126// Return the byte alignment of the given type (available at compile time). 127// Use like: 128// ALIGNOF(int32_t) // this would be 4 129#if defined(COMPILER_MSVC) 130#define ALIGNOF(type) __alignof(type) 131#elif defined(COMPILER_GCC) 132#define ALIGNOF(type) __alignof__(type) 133#endif 134 135// Annotate a function indicating the caller must examine the return value. 136// Use like: 137// int foo() WARN_UNUSED_RESULT; 138// To explicitly ignore a result, see |ignore_result()| in base/macros.h. 139#undef WARN_UNUSED_RESULT 140#if defined(COMPILER_GCC) || defined(__clang__) 141#define WARN_UNUSED_RESULT __attribute__((warn_unused_result)) 142#else 143#define WARN_UNUSED_RESULT 144#endif 145 146// Tell the compiler a function is using a printf-style format string. 147// |format_param| is the one-based index of the format string parameter; 148// |dots_param| is the one-based index of the "..." parameter. 149// For v*printf functions (which take a va_list), pass 0 for dots_param. 150// (This is undocumented but matches what the system C headers do.) 151#if defined(COMPILER_GCC) 152#define PRINTF_FORMAT(format_param, dots_param) \ 153 __attribute__((format(printf, format_param, dots_param))) 154#else 155#define PRINTF_FORMAT(format_param, dots_param) 156#endif 157 158// WPRINTF_FORMAT is the same, but for wide format strings. 159// This doesn't appear to yet be implemented in any compiler. 160// See http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38308 . 161#define WPRINTF_FORMAT(format_param, dots_param) 162// If available, it would look like: 163// __attribute__((format(wprintf, format_param, dots_param))) 164 165// Sanitizers annotations. 166#if defined(__has_attribute) 167#if __has_attribute(no_sanitize) 168#define NO_SANITIZE(what) __attribute__((no_sanitize(what))) 169#endif 170#endif 171#if !defined(NO_SANITIZE) 172#define NO_SANITIZE(what) 173#endif 174 175// MemorySanitizer annotations. 176#if defined(MEMORY_SANITIZER) && !defined(OS_NACL) 177#include <sanitizer/msan_interface.h> 178 179// Mark a memory region fully initialized. 180// Use this to annotate code that deliberately reads uninitialized data, for 181// example a GC scavenging root set pointers from the stack. 182#define MSAN_UNPOISON(p, size) __msan_unpoison(p, size) 183 184// Check a memory region for initializedness, as if it was being used here. 185// If any bits are uninitialized, crash with an MSan report. 186// Use this to sanitize data which MSan won't be able to track, e.g. before 187// passing data to another process via shared memory. 188#define MSAN_CHECK_MEM_IS_INITIALIZED(p, size) \ 189 __msan_check_mem_is_initialized(p, size) 190#else // MEMORY_SANITIZER 191#define MSAN_UNPOISON(p, size) 192#define MSAN_CHECK_MEM_IS_INITIALIZED(p, size) 193#endif // MEMORY_SANITIZER 194 195// DISABLE_CFI_PERF -- Disable Control Flow Integrity for perf reasons. 196#if !defined(DISABLE_CFI_PERF) 197#if defined(__clang__) && defined(OFFICIAL_BUILD) 198#define DISABLE_CFI_PERF __attribute__((no_sanitize("cfi"))) 199#else 200#define DISABLE_CFI_PERF 201#endif 202#endif 203 204// Macro useful for writing cross-platform function pointers. 205#if !defined(CDECL) 206#if defined(OS_WIN) 207#define CDECL __cdecl 208#else // defined(OS_WIN) 209#define CDECL 210#endif // defined(OS_WIN) 211#endif // !defined(CDECL) 212 213// Macro for hinting that an expression is likely to be false. 214#if !defined(UNLIKELY) 215#if defined(COMPILER_GCC) 216#define UNLIKELY(x) __builtin_expect(!!(x), 0) 217#else 218#define UNLIKELY(x) (x) 219#endif // defined(COMPILER_GCC) 220#endif // !defined(UNLIKELY) 221 222#if !defined(LIKELY) 223#if defined(COMPILER_GCC) 224#define LIKELY(x) __builtin_expect(!!(x), 1) 225#else 226#define LIKELY(x) (x) 227#endif // defined(COMPILER_GCC) 228#endif // !defined(LIKELY) 229 230// Compiler feature-detection. 231// clang.llvm.org/docs/LanguageExtensions.html#has-feature-and-has-extension 232#if defined(__has_feature) 233#define HAS_FEATURE(FEATURE) __has_feature(FEATURE) 234#else 235#define HAS_FEATURE(FEATURE) 0 236#endif 237 238#endif // BASE_COMPILER_SPECIFIC_H_ 239