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 /*---------------------------------------------------------------------------- 15 | The macro QEMU_GNUC_PREREQ tests for minimum version of the GNU C compiler. 16 | The code is a copy of SOFTFLOAT_GNUC_PREREQ, see softfloat-macros.h. 17 *----------------------------------------------------------------------------*/ 18 #if defined(__GNUC__) && defined(__GNUC_MINOR__) 19 # define QEMU_GNUC_PREREQ(maj, min) \ 20 ((__GNUC__ << 16) + __GNUC_MINOR__ >= ((maj) << 16) + (min)) 21 #else 22 # define QEMU_GNUC_PREREQ(maj, min) 0 23 #endif 24 25 #define QEMU_NORETURN __attribute__ ((__noreturn__)) 26 27 #define QEMU_WARN_UNUSED_RESULT __attribute__((warn_unused_result)) 28 29 #define QEMU_SENTINEL __attribute__((sentinel)) 30 31 #if defined(_WIN32) && (defined(__x86_64__) || defined(__i386__)) 32 # define QEMU_PACKED __attribute__((gcc_struct, packed)) 33 #else 34 # define QEMU_PACKED __attribute__((packed)) 35 #endif 36 37 #define QEMU_ALIGNED(X) __attribute__((aligned(X))) 38 39 #ifndef glue 40 #define xglue(x, y) x ## y 41 #define glue(x, y) xglue(x, y) 42 #define stringify(s) tostring(s) 43 #define tostring(s) #s 44 #endif 45 46 #ifndef likely 47 #if __GNUC__ < 3 48 #define __builtin_expect(x, n) (x) 49 #endif 50 51 #define likely(x) __builtin_expect(!!(x), 1) 52 #define unlikely(x) __builtin_expect(!!(x), 0) 53 #endif 54 55 #ifndef container_of 56 #define container_of(ptr, type, member) ({ \ 57 const typeof(((type *) 0)->member) *__mptr = (ptr); \ 58 (type *) ((char *) __mptr - offsetof(type, member));}) 59 #endif 60 61 #define sizeof_field(type, field) sizeof(((type *)0)->field) 62 63 /* 64 * Calculate the number of bytes up to and including the given 'field' of 65 * 'container'. 66 */ 67 #define endof(container, field) \ 68 (offsetof(container, field) + sizeof_field(container, field)) 69 70 /* Convert from a base type to a parent type, with compile time checking. */ 71 #ifdef __GNUC__ 72 #define DO_UPCAST(type, field, dev) ( __extension__ ( { \ 73 char __attribute__((unused)) offset_must_be_zero[ \ 74 -offsetof(type, field)]; \ 75 container_of(dev, type, field);})) 76 #else 77 #define DO_UPCAST(type, field, dev) container_of(dev, type, field) 78 #endif 79 80 #define typeof_field(type, field) typeof(((type *)0)->field) 81 #define type_check(t1,t2) ((t1*)0 - (t2*)0) 82 83 #define QEMU_BUILD_BUG_ON_STRUCT(x) \ 84 struct { \ 85 int:(x) ? -1 : 1; \ 86 } 87 88 /* QEMU_BUILD_BUG_MSG() emits the message given if _Static_assert is 89 * supported; otherwise, it will be omitted from the compiler error 90 * message (but as it remains present in the source code, it can still 91 * be useful when debugging). */ 92 #if defined(CONFIG_STATIC_ASSERT) 93 #define QEMU_BUILD_BUG_MSG(x, msg) _Static_assert(!(x), msg) 94 #elif defined(__COUNTER__) 95 #define QEMU_BUILD_BUG_MSG(x, msg) typedef QEMU_BUILD_BUG_ON_STRUCT(x) \ 96 glue(qemu_build_bug_on__, __COUNTER__) __attribute__((unused)) 97 #else 98 #define QEMU_BUILD_BUG_MSG(x, msg) 99 #endif 100 101 #define QEMU_BUILD_BUG_ON(x) QEMU_BUILD_BUG_MSG(x, "not expecting: " #x) 102 103 #define QEMU_BUILD_BUG_ON_ZERO(x) (sizeof(QEMU_BUILD_BUG_ON_STRUCT(x)) - \ 104 sizeof(QEMU_BUILD_BUG_ON_STRUCT(x))) 105 106 #if defined __GNUC__ 107 # if !QEMU_GNUC_PREREQ(4, 4) 108 /* gcc versions before 4.4.x don't support gnu_printf, so use printf. */ 109 # define GCC_FMT_ATTR(n, m) __attribute__((format(printf, n, m))) 110 # else 111 /* Use gnu_printf when supported (qemu uses standard format strings). */ 112 # define GCC_FMT_ATTR(n, m) __attribute__((format(gnu_printf, n, m))) 113 # if defined(_WIN32) 114 /* Map __printf__ to __gnu_printf__ because we want standard format strings 115 * even when MinGW or GLib include files use __printf__. */ 116 # define __printf__ __gnu_printf__ 117 # endif 118 # endif 119 #else 120 #define GCC_FMT_ATTR(n, m) 121 #endif 122 123 #ifndef __has_warning 124 #define __has_warning(x) 0 /* compatibility with non-clang compilers */ 125 #endif 126 127 #ifndef __has_feature 128 #define __has_feature(x) 0 /* compatibility with non-clang compilers */ 129 #endif 130 131 #ifndef __has_builtin 132 #define __has_builtin(x) 0 /* compatibility with non-clang compilers */ 133 #endif 134 135 #if __has_builtin(__builtin_assume_aligned) || !defined(__clang__) 136 #define HAS_ASSUME_ALIGNED 137 #endif 138 139 #ifndef __has_attribute 140 #define __has_attribute(x) 0 /* compatibility with older GCC */ 141 #endif 142 143 /* 144 * GCC doesn't provide __has_attribute() until GCC 5, but we know all the GCC 145 * versions we support have the "flatten" attribute. Clang may not have the 146 * "flatten" attribute but always has __has_attribute() to check for it. 147 */ 148 #if __has_attribute(flatten) || !defined(__clang__) 149 # define QEMU_FLATTEN __attribute__((flatten)) 150 #else 151 # define QEMU_FLATTEN 152 #endif 153 154 /* 155 * If __attribute__((error)) is present, use it to produce an error at 156 * compile time. Otherwise, one must wait for the linker to diagnose 157 * the missing symbol. 158 */ 159 #if __has_attribute(error) 160 # define QEMU_ERROR(X) __attribute__((error(X))) 161 #else 162 # define QEMU_ERROR(X) 163 #endif 164 165 /* 166 * The nonstring variable attribute specifies that an object or member 167 * declaration with type array of char or pointer to char is intended 168 * to store character arrays that do not necessarily contain a terminating 169 * NUL character. This is useful in detecting uses of such arrays or pointers 170 * with functions that expect NUL-terminated strings, and to avoid warnings 171 * when such an array or pointer is used as an argument to a bounded string 172 * manipulation function such as strncpy. 173 */ 174 #if __has_attribute(nonstring) 175 # define QEMU_NONSTRING __attribute__((nonstring)) 176 #else 177 # define QEMU_NONSTRING 178 #endif 179 180 /* 181 * Forced inlining may be desired to encourage constant propagation 182 * of function parameters. However, it can also make debugging harder, 183 * so disable it for a non-optimizing build. 184 */ 185 #if defined(__OPTIMIZE__) 186 #define QEMU_ALWAYS_INLINE __attribute__((always_inline)) 187 #else 188 #define QEMU_ALWAYS_INLINE 189 #endif 190 191 /* Implement C11 _Generic via GCC builtins. Example: 192 * 193 * QEMU_GENERIC(x, (float, sinf), (long double, sinl), sin) (x) 194 * 195 * The first argument is the discriminator. The last is the default value. 196 * The middle ones are tuples in "(type, expansion)" format. 197 */ 198 199 /* First, find out the number of generic cases. */ 200 #define QEMU_GENERIC(x, ...) \ 201 QEMU_GENERIC_(typeof(x), __VA_ARGS__, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0) 202 203 /* There will be extra arguments, but they are not used. */ 204 #define QEMU_GENERIC_(x, a0, a1, a2, a3, a4, a5, a6, a7, a8, a9, count, ...) \ 205 QEMU_GENERIC##count(x, a0, a1, a2, a3, a4, a5, a6, a7, a8, a9) 206 207 /* Two more helper macros, this time to extract items from a parenthesized 208 * list. 209 */ 210 #define QEMU_FIRST_(a, b) a 211 #define QEMU_SECOND_(a, b) b 212 213 /* ... and a final one for the common part of the "recursion". */ 214 #define QEMU_GENERIC_IF(x, type_then, else_) \ 215 __builtin_choose_expr(__builtin_types_compatible_p(x, \ 216 QEMU_FIRST_ type_then), \ 217 QEMU_SECOND_ type_then, else_) 218 219 /* CPP poor man's "recursion". */ 220 #define QEMU_GENERIC1(x, a0, ...) (a0) 221 #define QEMU_GENERIC2(x, a0, ...) QEMU_GENERIC_IF(x, a0, QEMU_GENERIC1(x, __VA_ARGS__)) 222 #define QEMU_GENERIC3(x, a0, ...) QEMU_GENERIC_IF(x, a0, QEMU_GENERIC2(x, __VA_ARGS__)) 223 #define QEMU_GENERIC4(x, a0, ...) QEMU_GENERIC_IF(x, a0, QEMU_GENERIC3(x, __VA_ARGS__)) 224 #define QEMU_GENERIC5(x, a0, ...) QEMU_GENERIC_IF(x, a0, QEMU_GENERIC4(x, __VA_ARGS__)) 225 #define QEMU_GENERIC6(x, a0, ...) QEMU_GENERIC_IF(x, a0, QEMU_GENERIC5(x, __VA_ARGS__)) 226 #define QEMU_GENERIC7(x, a0, ...) QEMU_GENERIC_IF(x, a0, QEMU_GENERIC6(x, __VA_ARGS__)) 227 #define QEMU_GENERIC8(x, a0, ...) QEMU_GENERIC_IF(x, a0, QEMU_GENERIC7(x, __VA_ARGS__)) 228 #define QEMU_GENERIC9(x, a0, ...) QEMU_GENERIC_IF(x, a0, QEMU_GENERIC8(x, __VA_ARGS__)) 229 #define QEMU_GENERIC10(x, a0, ...) QEMU_GENERIC_IF(x, a0, QEMU_GENERIC9(x, __VA_ARGS__)) 230 231 /** 232 * qemu_build_not_reached() 233 * 234 * The compiler, during optimization, is expected to prove that a call 235 * to this function cannot be reached and remove it. If the compiler 236 * supports QEMU_ERROR, this will be reported at compile time; otherwise 237 * this will be reported at link time due to the missing symbol. 238 */ 239 #if defined(__OPTIMIZE__) && !defined(__NO_INLINE__) 240 extern void QEMU_NORETURN QEMU_ERROR("code path is reachable") 241 qemu_build_not_reached(void); 242 #else 243 #define qemu_build_not_reached() g_assert_not_reached() 244 #endif 245 246 #endif /* COMPILER_H */ 247