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 #define HOST_BIG_ENDIAN (__BYTE_ORDER__ == __ORDER_BIG_ENDIAN__) 11 12 /* HOST_LONG_BITS is the size of a native pointer in bits. */ 13 #define HOST_LONG_BITS (__SIZEOF_POINTER__ * 8) 14 15 #if defined __clang_analyzer__ || defined __COVERITY__ 16 #define QEMU_STATIC_ANALYSIS 1 17 #endif 18 19 #ifdef __cplusplus 20 #define QEMU_EXTERN_C extern "C" 21 #else 22 #define QEMU_EXTERN_C extern 23 #endif 24 25 #define QEMU_NORETURN __attribute__ ((__noreturn__)) 26 27 #if defined(_WIN32) && (defined(__x86_64__) || defined(__i386__)) 28 # define QEMU_PACKED __attribute__((gcc_struct, packed)) 29 #else 30 # define QEMU_PACKED __attribute__((packed)) 31 #endif 32 33 #define QEMU_ALIGNED(X) __attribute__((aligned(X))) 34 35 #ifndef glue 36 #define xglue(x, y) x ## y 37 #define glue(x, y) xglue(x, y) 38 #define stringify(s) tostring(s) 39 #define tostring(s) #s 40 #endif 41 42 #ifndef likely 43 #define likely(x) __builtin_expect(!!(x), 1) 44 #define unlikely(x) __builtin_expect(!!(x), 0) 45 #endif 46 47 #ifndef container_of 48 #define container_of(ptr, type, member) ({ \ 49 const typeof(((type *) 0)->member) *__mptr = (ptr); \ 50 (type *) ((char *) __mptr - offsetof(type, member));}) 51 #endif 52 53 #define sizeof_field(type, field) sizeof(((type *)0)->field) 54 55 /* 56 * Calculate the number of bytes up to and including the given 'field' of 57 * 'container'. 58 */ 59 #define endof(container, field) \ 60 (offsetof(container, field) + sizeof_field(container, field)) 61 62 /* Convert from a base type to a parent type, with compile time checking. */ 63 #define DO_UPCAST(type, field, dev) ( __extension__ ( { \ 64 char __attribute__((unused)) offset_must_be_zero[ \ 65 -offsetof(type, field)]; \ 66 container_of(dev, type, field);})) 67 68 #define typeof_field(type, field) typeof(((type *)0)->field) 69 #define type_check(t1,t2) ((t1*)0 - (t2*)0) 70 71 #define QEMU_BUILD_BUG_ON_STRUCT(x) \ 72 struct { \ 73 int:(x) ? -1 : 1; \ 74 } 75 76 #define QEMU_BUILD_BUG_MSG(x, msg) _Static_assert(!(x), msg) 77 78 #define QEMU_BUILD_BUG_ON(x) QEMU_BUILD_BUG_MSG(x, "not expecting: " #x) 79 80 #define QEMU_BUILD_BUG_ON_ZERO(x) (sizeof(QEMU_BUILD_BUG_ON_STRUCT(x)) - \ 81 sizeof(QEMU_BUILD_BUG_ON_STRUCT(x))) 82 83 #if !defined(__clang__) && defined(_WIN32) 84 /* 85 * Map __printf__ to __gnu_printf__ because we want standard format strings even 86 * when MinGW or GLib include files use __printf__. 87 */ 88 # define __printf__ __gnu_printf__ 89 #endif 90 91 #ifndef __has_warning 92 #define __has_warning(x) 0 /* compatibility with non-clang compilers */ 93 #endif 94 95 #ifndef __has_feature 96 #define __has_feature(x) 0 /* compatibility with non-clang compilers */ 97 #endif 98 99 #ifndef __has_builtin 100 #define __has_builtin(x) 0 /* compatibility with non-clang compilers */ 101 #endif 102 103 #if __has_builtin(__builtin_assume_aligned) || !defined(__clang__) 104 #define HAS_ASSUME_ALIGNED 105 #endif 106 107 #ifndef __has_attribute 108 #define __has_attribute(x) 0 /* compatibility with older GCC */ 109 #endif 110 111 /* 112 * GCC doesn't provide __has_attribute() until GCC 5, but we know all the GCC 113 * versions we support have the "flatten" attribute. Clang may not have the 114 * "flatten" attribute but always has __has_attribute() to check for it. 115 */ 116 #if __has_attribute(flatten) || !defined(__clang__) 117 # define QEMU_FLATTEN __attribute__((flatten)) 118 #else 119 # define QEMU_FLATTEN 120 #endif 121 122 /* 123 * If __attribute__((error)) is present, use it to produce an error at 124 * compile time. Otherwise, one must wait for the linker to diagnose 125 * the missing symbol. 126 */ 127 #if __has_attribute(error) 128 # define QEMU_ERROR(X) __attribute__((error(X))) 129 #else 130 # define QEMU_ERROR(X) 131 #endif 132 133 /* 134 * The nonstring variable attribute specifies that an object or member 135 * declaration with type array of char or pointer to char is intended 136 * to store character arrays that do not necessarily contain a terminating 137 * NUL character. This is useful in detecting uses of such arrays or pointers 138 * with functions that expect NUL-terminated strings, and to avoid warnings 139 * when such an array or pointer is used as an argument to a bounded string 140 * manipulation function such as strncpy. 141 */ 142 #if __has_attribute(nonstring) 143 # define QEMU_NONSTRING __attribute__((nonstring)) 144 #else 145 # define QEMU_NONSTRING 146 #endif 147 148 /* 149 * Forced inlining may be desired to encourage constant propagation 150 * of function parameters. However, it can also make debugging harder, 151 * so disable it for a non-optimizing build. 152 */ 153 #if defined(__OPTIMIZE__) 154 #define QEMU_ALWAYS_INLINE __attribute__((always_inline)) 155 #else 156 #define QEMU_ALWAYS_INLINE 157 #endif 158 159 /** 160 * qemu_build_not_reached() 161 * 162 * The compiler, during optimization, is expected to prove that a call 163 * to this function cannot be reached and remove it. If the compiler 164 * supports QEMU_ERROR, this will be reported at compile time; otherwise 165 * this will be reported at link time due to the missing symbol. 166 */ 167 extern void QEMU_NORETURN QEMU_ERROR("code path is reachable") 168 qemu_build_not_reached_always(void); 169 #if defined(__OPTIMIZE__) && !defined(__NO_INLINE__) 170 #define qemu_build_not_reached() qemu_build_not_reached_always() 171 #else 172 #define qemu_build_not_reached() g_assert_not_reached() 173 #endif 174 175 /** 176 * In most cases, normal "fallthrough" comments are good enough for 177 * switch-case statements, but sometimes the compiler has problems 178 * with those. In that case you can use QEMU_FALLTHROUGH instead. 179 */ 180 #if __has_attribute(fallthrough) 181 # define QEMU_FALLTHROUGH __attribute__((fallthrough)) 182 #else 183 # define QEMU_FALLTHROUGH do {} while (0) /* fallthrough */ 184 #endif 185 186 #ifdef CONFIG_CFI 187 /* 188 * If CFI is enabled, use an attribute to disable cfi-icall on the following 189 * function 190 */ 191 #define QEMU_DISABLE_CFI __attribute__((no_sanitize("cfi-icall"))) 192 #else 193 /* If CFI is not enabled, use an empty define to not change the behavior */ 194 #define QEMU_DISABLE_CFI 195 #endif 196 197 #endif /* COMPILER_H */ 198