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__) && defined(_WIN32) 83 /* 84 * Map __printf__ to __gnu_printf__ because we want standard format strings even 85 * when MinGW or GLib include files use __printf__. 86 */ 87 # define __printf__ __gnu_printf__ 88 #endif 89 90 #ifndef __has_warning 91 #define __has_warning(x) 0 /* compatibility with non-clang compilers */ 92 #endif 93 94 #ifndef __has_feature 95 #define __has_feature(x) 0 /* compatibility with non-clang compilers */ 96 #endif 97 98 #ifndef __has_builtin 99 #define __has_builtin(x) 0 /* compatibility with non-clang compilers */ 100 #endif 101 102 #if __has_builtin(__builtin_assume_aligned) || !defined(__clang__) 103 #define HAS_ASSUME_ALIGNED 104 #endif 105 106 #ifndef __has_attribute 107 #define __has_attribute(x) 0 /* compatibility with older GCC */ 108 #endif 109 110 /* 111 * GCC doesn't provide __has_attribute() until GCC 5, but we know all the GCC 112 * versions we support have the "flatten" attribute. Clang may not have the 113 * "flatten" attribute but always has __has_attribute() to check for it. 114 */ 115 #if __has_attribute(flatten) || !defined(__clang__) 116 # define QEMU_FLATTEN __attribute__((flatten)) 117 #else 118 # define QEMU_FLATTEN 119 #endif 120 121 /* 122 * If __attribute__((error)) is present, use it to produce an error at 123 * compile time. Otherwise, one must wait for the linker to diagnose 124 * the missing symbol. 125 */ 126 #if __has_attribute(error) 127 # define QEMU_ERROR(X) __attribute__((error(X))) 128 #else 129 # define QEMU_ERROR(X) 130 #endif 131 132 /* 133 * The nonstring variable attribute specifies that an object or member 134 * declaration with type array of char or pointer to char is intended 135 * to store character arrays that do not necessarily contain a terminating 136 * NUL character. This is useful in detecting uses of such arrays or pointers 137 * with functions that expect NUL-terminated strings, and to avoid warnings 138 * when such an array or pointer is used as an argument to a bounded string 139 * manipulation function such as strncpy. 140 */ 141 #if __has_attribute(nonstring) 142 # define QEMU_NONSTRING __attribute__((nonstring)) 143 #else 144 # define QEMU_NONSTRING 145 #endif 146 147 /* 148 * Forced inlining may be desired to encourage constant propagation 149 * of function parameters. However, it can also make debugging harder, 150 * so disable it for a non-optimizing build. 151 */ 152 #if defined(__OPTIMIZE__) 153 #define QEMU_ALWAYS_INLINE __attribute__((always_inline)) 154 #else 155 #define QEMU_ALWAYS_INLINE 156 #endif 157 158 /** 159 * qemu_build_not_reached() 160 * 161 * The compiler, during optimization, is expected to prove that a call 162 * to this function cannot be reached and remove it. If the compiler 163 * supports QEMU_ERROR, this will be reported at compile time; otherwise 164 * this will be reported at link time due to the missing symbol. 165 */ 166 extern void QEMU_NORETURN QEMU_ERROR("code path is reachable") 167 qemu_build_not_reached_always(void); 168 #if defined(__OPTIMIZE__) && !defined(__NO_INLINE__) 169 #define qemu_build_not_reached() qemu_build_not_reached_always() 170 #else 171 #define qemu_build_not_reached() g_assert_not_reached() 172 #endif 173 174 /** 175 * In most cases, normal "fallthrough" comments are good enough for 176 * switch-case statements, but sometimes the compiler has problems 177 * with those. In that case you can use QEMU_FALLTHROUGH instead. 178 */ 179 #if __has_attribute(fallthrough) 180 # define QEMU_FALLTHROUGH __attribute__((fallthrough)) 181 #else 182 # define QEMU_FALLTHROUGH do {} while (0) /* fallthrough */ 183 #endif 184 185 #ifdef CONFIG_CFI 186 /* 187 * If CFI is enabled, use an attribute to disable cfi-icall on the following 188 * function 189 */ 190 #define QEMU_DISABLE_CFI __attribute__((no_sanitize("cfi-icall"))) 191 #else 192 /* If CFI is not enabled, use an empty define to not change the behavior */ 193 #define QEMU_DISABLE_CFI 194 #endif 195 196 #endif /* COMPILER_H */ 197