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 #ifdef __cplusplus 15 #define QEMU_EXTERN_C extern "C" 16 #else 17 #define QEMU_EXTERN_C extern 18 #endif 19 20 #define QEMU_NORETURN __attribute__ ((__noreturn__)) 21 22 #define QEMU_WARN_UNUSED_RESULT __attribute__((warn_unused_result)) 23 24 #define QEMU_SENTINEL __attribute__((sentinel)) 25 26 #if defined(_WIN32) && (defined(__x86_64__) || defined(__i386__)) 27 # define QEMU_PACKED __attribute__((gcc_struct, packed)) 28 #else 29 # define QEMU_PACKED __attribute__((packed)) 30 #endif 31 32 #define QEMU_ALIGNED(X) __attribute__((aligned(X))) 33 34 #ifndef glue 35 #define xglue(x, y) x ## y 36 #define glue(x, y) xglue(x, y) 37 #define stringify(s) tostring(s) 38 #define tostring(s) #s 39 #endif 40 41 #ifndef likely 42 #define likely(x) __builtin_expect(!!(x), 1) 43 #define unlikely(x) __builtin_expect(!!(x), 0) 44 #endif 45 46 #ifndef container_of 47 #define container_of(ptr, type, member) ({ \ 48 const typeof(((type *) 0)->member) *__mptr = (ptr); \ 49 (type *) ((char *) __mptr - offsetof(type, member));}) 50 #endif 51 52 #define sizeof_field(type, field) sizeof(((type *)0)->field) 53 54 /* 55 * Calculate the number of bytes up to and including the given 'field' of 56 * 'container'. 57 */ 58 #define endof(container, field) \ 59 (offsetof(container, field) + sizeof_field(container, field)) 60 61 /* Convert from a base type to a parent type, with compile time checking. */ 62 #define DO_UPCAST(type, field, dev) ( __extension__ ( { \ 63 char __attribute__((unused)) offset_must_be_zero[ \ 64 -offsetof(type, field)]; \ 65 container_of(dev, type, field);})) 66 67 #define typeof_field(type, field) typeof(((type *)0)->field) 68 #define type_check(t1,t2) ((t1*)0 - (t2*)0) 69 70 #define QEMU_BUILD_BUG_ON_STRUCT(x) \ 71 struct { \ 72 int:(x) ? -1 : 1; \ 73 } 74 75 #define QEMU_BUILD_BUG_MSG(x, msg) _Static_assert(!(x), msg) 76 77 #define QEMU_BUILD_BUG_ON(x) QEMU_BUILD_BUG_MSG(x, "not expecting: " #x) 78 79 #define QEMU_BUILD_BUG_ON_ZERO(x) (sizeof(QEMU_BUILD_BUG_ON_STRUCT(x)) - \ 80 sizeof(QEMU_BUILD_BUG_ON_STRUCT(x))) 81 82 #if defined(__clang__) 83 /* clang doesn't support gnu_printf, so use printf. */ 84 # define GCC_FMT_ATTR(n, m) __attribute__((format(printf, n, m))) 85 #else 86 /* Use gnu_printf (qemu uses standard format strings). */ 87 # define GCC_FMT_ATTR(n, m) __attribute__((format(gnu_printf, n, m))) 88 # if defined(_WIN32) 89 /* 90 * Map __printf__ to __gnu_printf__ because we want standard format strings even 91 * when MinGW or GLib include files use __printf__. 92 */ 93 # define __printf__ __gnu_printf__ 94 # endif 95 #endif 96 97 #ifndef __has_warning 98 #define __has_warning(x) 0 /* compatibility with non-clang compilers */ 99 #endif 100 101 #ifndef __has_feature 102 #define __has_feature(x) 0 /* compatibility with non-clang compilers */ 103 #endif 104 105 #ifndef __has_builtin 106 #define __has_builtin(x) 0 /* compatibility with non-clang compilers */ 107 #endif 108 109 #if __has_builtin(__builtin_assume_aligned) || !defined(__clang__) 110 #define HAS_ASSUME_ALIGNED 111 #endif 112 113 #ifndef __has_attribute 114 #define __has_attribute(x) 0 /* compatibility with older GCC */ 115 #endif 116 117 /* 118 * GCC doesn't provide __has_attribute() until GCC 5, but we know all the GCC 119 * versions we support have the "flatten" attribute. Clang may not have the 120 * "flatten" attribute but always has __has_attribute() to check for it. 121 */ 122 #if __has_attribute(flatten) || !defined(__clang__) 123 # define QEMU_FLATTEN __attribute__((flatten)) 124 #else 125 # define QEMU_FLATTEN 126 #endif 127 128 /* 129 * If __attribute__((error)) is present, use it to produce an error at 130 * compile time. Otherwise, one must wait for the linker to diagnose 131 * the missing symbol. 132 */ 133 #if __has_attribute(error) 134 # define QEMU_ERROR(X) __attribute__((error(X))) 135 #else 136 # define QEMU_ERROR(X) 137 #endif 138 139 /* 140 * The nonstring variable attribute specifies that an object or member 141 * declaration with type array of char or pointer to char is intended 142 * to store character arrays that do not necessarily contain a terminating 143 * NUL character. This is useful in detecting uses of such arrays or pointers 144 * with functions that expect NUL-terminated strings, and to avoid warnings 145 * when such an array or pointer is used as an argument to a bounded string 146 * manipulation function such as strncpy. 147 */ 148 #if __has_attribute(nonstring) 149 # define QEMU_NONSTRING __attribute__((nonstring)) 150 #else 151 # define QEMU_NONSTRING 152 #endif 153 154 /* 155 * Forced inlining may be desired to encourage constant propagation 156 * of function parameters. However, it can also make debugging harder, 157 * so disable it for a non-optimizing build. 158 */ 159 #if defined(__OPTIMIZE__) 160 #define QEMU_ALWAYS_INLINE __attribute__((always_inline)) 161 #else 162 #define QEMU_ALWAYS_INLINE 163 #endif 164 165 /** 166 * qemu_build_not_reached() 167 * 168 * The compiler, during optimization, is expected to prove that a call 169 * to this function cannot be reached and remove it. If the compiler 170 * supports QEMU_ERROR, this will be reported at compile time; otherwise 171 * this will be reported at link time due to the missing symbol. 172 */ 173 extern void QEMU_NORETURN QEMU_ERROR("code path is reachable") 174 qemu_build_not_reached_always(void); 175 #if defined(__OPTIMIZE__) && !defined(__NO_INLINE__) 176 #define qemu_build_not_reached() qemu_build_not_reached_always() 177 #else 178 #define qemu_build_not_reached() g_assert_not_reached() 179 #endif 180 181 /** 182 * In most cases, normal "fallthrough" comments are good enough for 183 * switch-case statements, but sometimes the compiler has problems 184 * with those. In that case you can use QEMU_FALLTHROUGH instead. 185 */ 186 #if __has_attribute(fallthrough) 187 # define QEMU_FALLTHROUGH __attribute__((fallthrough)) 188 #else 189 # define QEMU_FALLTHROUGH do {} while (0) /* fallthrough */ 190 #endif 191 192 #ifdef CONFIG_CFI 193 /* 194 * If CFI is enabled, use an attribute to disable cfi-icall on the following 195 * function 196 */ 197 #define QEMU_DISABLE_CFI __attribute__((no_sanitize("cfi-icall"))) 198 #else 199 /* If CFI is not enabled, use an empty define to not change the behavior */ 200 #define QEMU_DISABLE_CFI 201 #endif 202 203 #endif /* COMPILER_H */ 204