1 /* compiler.h: macros to abstract away compiler specifics 2 * 3 * This work is licensed under the terms of the GNU GPL, version 2 or later. 4 * See the COPYING file in the top-level directory. 5 */ 6 7 #ifndef COMPILER_H 8 #define COMPILER_H 9 10 #if defined __clang_analyzer__ || defined __COVERITY__ 11 #define QEMU_STATIC_ANALYSIS 1 12 #endif 13 14 #define QEMU_NORETURN __attribute__ ((__noreturn__)) 15 16 #define QEMU_WARN_UNUSED_RESULT __attribute__((warn_unused_result)) 17 18 #define QEMU_SENTINEL __attribute__((sentinel)) 19 20 #if defined(_WIN32) && (defined(__x86_64__) || defined(__i386__)) 21 # define QEMU_PACKED __attribute__((gcc_struct, packed)) 22 #else 23 # define QEMU_PACKED __attribute__((packed)) 24 #endif 25 26 #define QEMU_ALIGNED(X) __attribute__((aligned(X))) 27 28 #ifndef glue 29 #define xglue(x, y) x ## y 30 #define glue(x, y) xglue(x, y) 31 #define stringify(s) tostring(s) 32 #define tostring(s) #s 33 #endif 34 35 #ifndef likely 36 #define likely(x) __builtin_expect(!!(x), 1) 37 #define unlikely(x) __builtin_expect(!!(x), 0) 38 #endif 39 40 #ifndef container_of 41 #define container_of(ptr, type, member) ({ \ 42 const typeof(((type *) 0)->member) *__mptr = (ptr); \ 43 (type *) ((char *) __mptr - offsetof(type, member));}) 44 #endif 45 46 #define sizeof_field(type, field) sizeof(((type *)0)->field) 47 48 /* 49 * Calculate the number of bytes up to and including the given 'field' of 50 * 'container'. 51 */ 52 #define endof(container, field) \ 53 (offsetof(container, field) + sizeof_field(container, field)) 54 55 /* Convert from a base type to a parent type, with compile time checking. */ 56 #define DO_UPCAST(type, field, dev) ( __extension__ ( { \ 57 char __attribute__((unused)) offset_must_be_zero[ \ 58 -offsetof(type, field)]; \ 59 container_of(dev, type, field);})) 60 61 #define typeof_field(type, field) typeof(((type *)0)->field) 62 #define type_check(t1,t2) ((t1*)0 - (t2*)0) 63 64 #define QEMU_BUILD_BUG_ON_STRUCT(x) \ 65 struct { \ 66 int:(x) ? -1 : 1; \ 67 } 68 69 /* QEMU_BUILD_BUG_MSG() emits the message given if _Static_assert is 70 * supported; otherwise, it will be omitted from the compiler error 71 * message (but as it remains present in the source code, it can still 72 * be useful when debugging). */ 73 #if defined(CONFIG_STATIC_ASSERT) 74 #define QEMU_BUILD_BUG_MSG(x, msg) _Static_assert(!(x), msg) 75 #elif defined(__COUNTER__) 76 #define QEMU_BUILD_BUG_MSG(x, msg) typedef QEMU_BUILD_BUG_ON_STRUCT(x) \ 77 glue(qemu_build_bug_on__, __COUNTER__) __attribute__((unused)) 78 #else 79 #define QEMU_BUILD_BUG_MSG(x, msg) 80 #endif 81 82 #define QEMU_BUILD_BUG_ON(x) QEMU_BUILD_BUG_MSG(x, "not expecting: " #x) 83 84 #define QEMU_BUILD_BUG_ON_ZERO(x) (sizeof(QEMU_BUILD_BUG_ON_STRUCT(x)) - \ 85 sizeof(QEMU_BUILD_BUG_ON_STRUCT(x))) 86 87 #if defined(__clang__) 88 /* clang doesn't support gnu_printf, so use printf. */ 89 # define GCC_FMT_ATTR(n, m) __attribute__((format(printf, n, m))) 90 #else 91 /* Use gnu_printf (qemu uses standard format strings). */ 92 # define GCC_FMT_ATTR(n, m) __attribute__((format(gnu_printf, n, m))) 93 # if defined(_WIN32) 94 /* 95 * Map __printf__ to __gnu_printf__ because we want standard format strings even 96 * when MinGW or GLib include files use __printf__. 97 */ 98 # define __printf__ __gnu_printf__ 99 # endif 100 #endif 101 102 #ifndef __has_warning 103 #define __has_warning(x) 0 /* compatibility with non-clang compilers */ 104 #endif 105 106 #ifndef __has_feature 107 #define __has_feature(x) 0 /* compatibility with non-clang compilers */ 108 #endif 109 110 #ifndef __has_builtin 111 #define __has_builtin(x) 0 /* compatibility with non-clang compilers */ 112 #endif 113 114 #if __has_builtin(__builtin_assume_aligned) || !defined(__clang__) 115 #define HAS_ASSUME_ALIGNED 116 #endif 117 118 #ifndef __has_attribute 119 #define __has_attribute(x) 0 /* compatibility with older GCC */ 120 #endif 121 122 /* 123 * GCC doesn't provide __has_attribute() until GCC 5, but we know all the GCC 124 * versions we support have the "flatten" attribute. Clang may not have the 125 * "flatten" attribute but always has __has_attribute() to check for it. 126 */ 127 #if __has_attribute(flatten) || !defined(__clang__) 128 # define QEMU_FLATTEN __attribute__((flatten)) 129 #else 130 # define QEMU_FLATTEN 131 #endif 132 133 /* 134 * If __attribute__((error)) is present, use it to produce an error at 135 * compile time. Otherwise, one must wait for the linker to diagnose 136 * the missing symbol. 137 */ 138 #if __has_attribute(error) 139 # define QEMU_ERROR(X) __attribute__((error(X))) 140 #else 141 # define QEMU_ERROR(X) 142 #endif 143 144 /* 145 * The nonstring variable attribute specifies that an object or member 146 * declaration with type array of char or pointer to char is intended 147 * to store character arrays that do not necessarily contain a terminating 148 * NUL character. This is useful in detecting uses of such arrays or pointers 149 * with functions that expect NUL-terminated strings, and to avoid warnings 150 * when such an array or pointer is used as an argument to a bounded string 151 * manipulation function such as strncpy. 152 */ 153 #if __has_attribute(nonstring) 154 # define QEMU_NONSTRING __attribute__((nonstring)) 155 #else 156 # define QEMU_NONSTRING 157 #endif 158 159 /* 160 * Forced inlining may be desired to encourage constant propagation 161 * of function parameters. However, it can also make debugging harder, 162 * so disable it for a non-optimizing build. 163 */ 164 #if defined(__OPTIMIZE__) 165 #define QEMU_ALWAYS_INLINE __attribute__((always_inline)) 166 #else 167 #define QEMU_ALWAYS_INLINE 168 #endif 169 170 /* Implement C11 _Generic via GCC builtins. Example: 171 * 172 * QEMU_GENERIC(x, (float, sinf), (long double, sinl), sin) (x) 173 * 174 * The first argument is the discriminator. The last is the default value. 175 * The middle ones are tuples in "(type, expansion)" format. 176 */ 177 178 /* First, find out the number of generic cases. */ 179 #define QEMU_GENERIC(x, ...) \ 180 QEMU_GENERIC_(typeof(x), __VA_ARGS__, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0) 181 182 /* There will be extra arguments, but they are not used. */ 183 #define QEMU_GENERIC_(x, a0, a1, a2, a3, a4, a5, a6, a7, a8, a9, count, ...) \ 184 QEMU_GENERIC##count(x, a0, a1, a2, a3, a4, a5, a6, a7, a8, a9) 185 186 /* Two more helper macros, this time to extract items from a parenthesized 187 * list. 188 */ 189 #define QEMU_FIRST_(a, b) a 190 #define QEMU_SECOND_(a, b) b 191 192 /* ... and a final one for the common part of the "recursion". */ 193 #define QEMU_GENERIC_IF(x, type_then, else_) \ 194 __builtin_choose_expr(__builtin_types_compatible_p(x, \ 195 QEMU_FIRST_ type_then), \ 196 QEMU_SECOND_ type_then, else_) 197 198 /* CPP poor man's "recursion". */ 199 #define QEMU_GENERIC1(x, a0, ...) (a0) 200 #define QEMU_GENERIC2(x, a0, ...) QEMU_GENERIC_IF(x, a0, QEMU_GENERIC1(x, __VA_ARGS__)) 201 #define QEMU_GENERIC3(x, a0, ...) QEMU_GENERIC_IF(x, a0, QEMU_GENERIC2(x, __VA_ARGS__)) 202 #define QEMU_GENERIC4(x, a0, ...) QEMU_GENERIC_IF(x, a0, QEMU_GENERIC3(x, __VA_ARGS__)) 203 #define QEMU_GENERIC5(x, a0, ...) QEMU_GENERIC_IF(x, a0, QEMU_GENERIC4(x, __VA_ARGS__)) 204 #define QEMU_GENERIC6(x, a0, ...) QEMU_GENERIC_IF(x, a0, QEMU_GENERIC5(x, __VA_ARGS__)) 205 #define QEMU_GENERIC7(x, a0, ...) QEMU_GENERIC_IF(x, a0, QEMU_GENERIC6(x, __VA_ARGS__)) 206 #define QEMU_GENERIC8(x, a0, ...) QEMU_GENERIC_IF(x, a0, QEMU_GENERIC7(x, __VA_ARGS__)) 207 #define QEMU_GENERIC9(x, a0, ...) QEMU_GENERIC_IF(x, a0, QEMU_GENERIC8(x, __VA_ARGS__)) 208 #define QEMU_GENERIC10(x, a0, ...) QEMU_GENERIC_IF(x, a0, QEMU_GENERIC9(x, __VA_ARGS__)) 209 210 /** 211 * qemu_build_not_reached() 212 * 213 * The compiler, during optimization, is expected to prove that a call 214 * to this function cannot be reached and remove it. If the compiler 215 * supports QEMU_ERROR, this will be reported at compile time; otherwise 216 * this will be reported at link time due to the missing symbol. 217 */ 218 #if defined(__OPTIMIZE__) && !defined(__NO_INLINE__) 219 extern void QEMU_NORETURN QEMU_ERROR("code path is reachable") 220 qemu_build_not_reached(void); 221 #else 222 #define qemu_build_not_reached() g_assert_not_reached() 223 #endif 224 225 /** 226 * In most cases, normal "fallthrough" comments are good enough for 227 * switch-case statements, but sometimes the compiler has problems 228 * with those. In that case you can use QEMU_FALLTHROUGH instead. 229 */ 230 #if __has_attribute(fallthrough) 231 # define QEMU_FALLTHROUGH __attribute__((fallthrough)) 232 #else 233 # define QEMU_FALLTHROUGH do {} while (0) /* fallthrough */ 234 #endif 235 236 #ifdef CONFIG_CFI 237 /* 238 * If CFI is enabled, use an attribute to disable cfi-icall on the following 239 * function 240 */ 241 #define QEMU_DISABLE_CFI __attribute__((no_sanitize("cfi-icall"))) 242 #else 243 /* If CFI is not enabled, use an empty define to not change the behavior */ 244 #define QEMU_DISABLE_CFI 245 #endif 246 247 #endif /* COMPILER_H */ 248