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 "util/build_config.h" 9 10 #if defined(COMPILER_MSVC) 11 12 // For _Printf_format_string_. 13 #include <sal.h> 14 15 // Macros for suppressing and disabling warnings on MSVC. 16 // 17 // Warning numbers are enumerated at: 18 // http://msdn.microsoft.com/en-us/library/8x5x43k7(VS.80).aspx 19 // 20 // The warning pragma: 21 // http://msdn.microsoft.com/en-us/library/2c8f766e(VS.80).aspx 22 // 23 // Using __pragma instead of #pragma inside macros: 24 // http://msdn.microsoft.com/en-us/library/d9x1s805.aspx 25 26 // MSVC_SUPPRESS_WARNING disables warning |n| for the remainder of the line and 27 // for the next line of the source file. 28 #define MSVC_SUPPRESS_WARNING(n) __pragma(warning(suppress : n)) 29 30 // MSVC_PUSH_DISABLE_WARNING pushes |n| onto a stack of warnings to be disabled. 31 // The warning remains disabled until popped by MSVC_POP_WARNING. 32 #define MSVC_PUSH_DISABLE_WARNING(n) \ 33 __pragma(warning(push)) __pragma(warning(disable : n)) 34 35 // MSVC_PUSH_WARNING_LEVEL pushes |n| as the global warning level. The level 36 // remains in effect until popped by MSVC_POP_WARNING(). Use 0 to disable all 37 // warnings. 38 #define MSVC_PUSH_WARNING_LEVEL(n) __pragma(warning(push, n)) 39 40 // Pop effects of innermost MSVC_PUSH_* macro. 41 #define MSVC_POP_WARNING() __pragma(warning(pop)) 42 43 #define MSVC_DISABLE_OPTIMIZE() __pragma(optimize("", off)) 44 #define MSVC_ENABLE_OPTIMIZE() __pragma(optimize("", on)) 45 46 #else // Not MSVC 47 48 #define _Printf_format_string_ 49 #define MSVC_SUPPRESS_WARNING(n) 50 #define MSVC_PUSH_DISABLE_WARNING(n) 51 #define MSVC_PUSH_WARNING_LEVEL(n) 52 #define MSVC_POP_WARNING() 53 #define MSVC_DISABLE_OPTIMIZE() 54 #define MSVC_ENABLE_OPTIMIZE() 55 56 #endif // COMPILER_MSVC 57 58 // Annotate a variable indicating it's ok if the variable is not used. 59 // (Typically used to silence a compiler warning when the assignment 60 // is important for some other reason.) 61 // Use like: 62 // int x = ...; 63 // ALLOW_UNUSED_LOCAL(x); 64 #define ALLOW_UNUSED_LOCAL(x) (void)x 65 66 // Annotate a typedef or function indicating it's ok if it's not used. 67 // Use like: 68 // typedef Foo Bar ALLOW_UNUSED_TYPE; 69 #if defined(COMPILER_GCC) || defined(__clang__) 70 #define ALLOW_UNUSED_TYPE __attribute__((unused)) 71 #else 72 #define ALLOW_UNUSED_TYPE 73 #endif 74 75 // Annotate a function indicating it should not be inlined. 76 // Use like: 77 // NOINLINE void DoStuff() { ... } 78 #if defined(COMPILER_GCC) 79 #define NOINLINE __attribute__((noinline)) 80 #elif defined(COMPILER_MSVC) 81 #define NOINLINE __declspec(noinline) 82 #else 83 #define NOINLINE 84 #endif 85 86 #if COMPILER_GCC && defined(NDEBUG) 87 #define ALWAYS_INLINE inline __attribute__((__always_inline__)) 88 #elif COMPILER_MSVC && defined(NDEBUG) 89 #define ALWAYS_INLINE __forceinline 90 #else 91 #define ALWAYS_INLINE inline 92 #endif 93 94 // Specify memory alignment for structs, classes, etc. 95 // Use like: 96 // class ALIGNAS(16) MyClass { ... } 97 // ALIGNAS(16) int array[4]; 98 // 99 // In most places you can use the C++11 keyword "alignas", which is preferred. 100 // 101 // But compilers have trouble mixing __attribute__((...)) syntax with 102 // alignas(...) syntax. 103 // 104 // Doesn't work in clang or gcc: 105 // struct alignas(16) __attribute__((packed)) S { char c; }; 106 // Works in clang but not gcc: 107 // struct __attribute__((packed)) alignas(16) S2 { char c; }; 108 // Works in clang and gcc: 109 // struct alignas(16) S3 { char c; } __attribute__((packed)); 110 // 111 // There are also some attributes that must be specified *before* a class 112 // definition: visibility (used for exporting functions/classes) is one of 113 // these attributes. This means that it is not possible to use alignas() with a 114 // class that is marked as exported. 115 #if defined(COMPILER_MSVC) 116 #define ALIGNAS(byte_alignment) __declspec(align(byte_alignment)) 117 #elif defined(COMPILER_GCC) 118 #define ALIGNAS(byte_alignment) __attribute__((aligned(byte_alignment))) 119 #endif 120 121 // Annotate a function indicating the caller must examine the return value. 122 // Use like: 123 // int foo() WARN_UNUSED_RESULT; 124 // To explicitly ignore a result, see |ignore_result()| in base/macros.h. 125 #undef WARN_UNUSED_RESULT 126 #if defined(COMPILER_GCC) || defined(__clang__) 127 #define WARN_UNUSED_RESULT __attribute__((warn_unused_result)) 128 #else 129 #define WARN_UNUSED_RESULT 130 #endif 131 132 // Tell the compiler a function is using a printf-style format string. 133 // |format_param| is the one-based index of the format string parameter; 134 // |dots_param| is the one-based index of the "..." parameter. 135 // For v*printf functions (which take a va_list), pass 0 for dots_param. 136 // (This is undocumented but matches what the system C headers do.) 137 #if defined(COMPILER_GCC) || defined(__clang__) 138 #define PRINTF_FORMAT(format_param, dots_param) \ 139 __attribute__((format(printf, format_param, dots_param))) 140 #else 141 #define PRINTF_FORMAT(format_param, dots_param) 142 #endif 143 144 // WPRINTF_FORMAT is the same, but for wide format strings. 145 // This doesn't appear to yet be implemented in any compiler. 146 // See http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38308 . 147 #define WPRINTF_FORMAT(format_param, dots_param) 148 // If available, it would look like: 149 // __attribute__((format(wprintf, format_param, dots_param))) 150 151 // Sanitizers annotations. 152 #if defined(__has_attribute) 153 #if __has_attribute(no_sanitize) 154 #define NO_SANITIZE(what) __attribute__((no_sanitize(what))) 155 #endif 156 #endif 157 #if !defined(NO_SANITIZE) 158 #define NO_SANITIZE(what) 159 #endif 160 161 // MemorySanitizer annotations. 162 #if defined(MEMORY_SANITIZER) 163 #include <sanitizer/msan_interface.h> 164 165 // Mark a memory region fully initialized. 166 // Use this to annotate code that deliberately reads uninitialized data, for 167 // example a GC scavenging root set pointers from the stack. 168 #define MSAN_UNPOISON(p, size) __msan_unpoison(p, size) 169 170 // Check a memory region for initializedness, as if it was being used here. 171 // If any bits are uninitialized, crash with an MSan report. 172 // Use this to sanitize data which MSan won't be able to track, e.g. before 173 // passing data to another process via shared memory. 174 #define MSAN_CHECK_MEM_IS_INITIALIZED(p, size) \ 175 __msan_check_mem_is_initialized(p, size) 176 #else // MEMORY_SANITIZER 177 #define MSAN_UNPOISON(p, size) 178 #define MSAN_CHECK_MEM_IS_INITIALIZED(p, size) 179 #endif // MEMORY_SANITIZER 180 181 // DISABLE_CFI_PERF -- Disable Control Flow Integrity for perf reasons. 182 #if !defined(DISABLE_CFI_PERF) 183 #if defined(__clang__) && defined(OFFICIAL_BUILD) 184 #define DISABLE_CFI_PERF __attribute__((no_sanitize("cfi"))) 185 #else 186 #define DISABLE_CFI_PERF 187 #endif 188 #endif 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) || defined(__clang__) 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 #if !defined(LIKELY) 209 #if defined(COMPILER_GCC) || defined(__clang__) 210 #define LIKELY(x) __builtin_expect(!!(x), 1) 211 #else 212 #define LIKELY(x) (x) 213 #endif // defined(COMPILER_GCC) 214 #endif // !defined(LIKELY) 215 216 // Compiler feature-detection. 217 // clang.llvm.org/docs/LanguageExtensions.html#has-feature-and-has-extension 218 #if defined(__has_feature) 219 #define HAS_FEATURE(FEATURE) __has_feature(FEATURE) 220 #else 221 #define HAS_FEATURE(FEATURE) 0 222 #endif 223 224 // Macro for telling -Wimplicit-fallthrough that a fallthrough is intentional. 225 #if defined(__clang__) 226 #define FALLTHROUGH [[clang::fallthrough]] 227 #else 228 #define FALLTHROUGH 229 #endif 230 231 #endif // BASE_COMPILER_SPECIFIC_H_ 232