include/qemu/compiler.h

   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 #if defined(_WIN32) && (defined(__x86_64__) || defined(__i386__))
  26 # define QEMU_PACKED __attribute__((gcc_struct, packed))
  27 #else
  28 # define QEMU_PACKED __attribute__((packed))
  29 #endif
  30
  31 #define QEMU_ALIGNED(X) __attribute__((aligned(X)))
  32
  33 #ifndef glue
  34 #define xglue(x, y) x ## y
  35 #define glue(x, y) xglue(x, y)
  36 #define stringify(s) tostring(s)
  37 #define tostring(s) #s
  38 #endif
  39
  40 #ifndef likely
  41 #define likely(x)   __builtin_expect(!!(x), 1)
  42 #define unlikely(x)   __builtin_expect(!!(x), 0)
  43 #endif
  44
  45 #ifndef container_of
  46 #define container_of(ptr, type, member) ({                      \
  47         const typeof(((type *) 0)->member) *__mptr = (ptr);     \
  48         (type *) ((char *) __mptr - offsetof(type, member));})
  49 #endif
  50
  51 #define sizeof_field(type, field) sizeof(((type *)0)->field)
  52
  53 /*
  54  * Calculate the number of bytes up to and including the given 'field' of
  55  * 'container'.
  56  */
  57 #define endof(container, field) \
  58     (offsetof(container, field) + sizeof_field(container, field))
  59
  60 /* Convert from a base type to a parent type, with compile time checking.  */
  61 #define DO_UPCAST(type, field, dev) ( __extension__ ( { \
  62     char __attribute__((unused)) offset_must_be_zero[ \
  63         -offsetof(type, field)]; \
  64     container_of(dev, type, field);}))
  65
  66 #define typeof_field(type, field) typeof(((type *)0)->field)
  67 #define type_check(t1,t2) ((t1*)0 - (t2*)0)
  68
  69 #define QEMU_BUILD_BUG_ON_STRUCT(x) \
  70     struct { \
  71         int:(x) ? -1 : 1; \
  72     }
  73
  74 #define QEMU_BUILD_BUG_MSG(x, msg) _Static_assert(!(x), msg)
  75
  76 #define QEMU_BUILD_BUG_ON(x) QEMU_BUILD_BUG_MSG(x, "not expecting: " #x)
  77
  78 #define QEMU_BUILD_BUG_ON_ZERO(x) (sizeof(QEMU_BUILD_BUG_ON_STRUCT(x)) - \
  79                                    sizeof(QEMU_BUILD_BUG_ON_STRUCT(x)))
  80
  81 #if !defined(__clang__) && defined(_WIN32)
  82 /*
  83  * Map __printf__ to __gnu_printf__ because we want standard format strings even
  84  * when MinGW or GLib include files use __printf__.
  85  */
  86 # define __printf__ __gnu_printf__
  87 #endif
  88
  89 #ifndef __has_warning
  90 #define __has_warning(x) 0 /* compatibility with non-clang compilers */
  91 #endif
  92
  93 #ifndef __has_feature
  94 #define __has_feature(x) 0 /* compatibility with non-clang compilers */
  95 #endif
  96
  97 #ifndef __has_builtin
  98 #define __has_builtin(x) 0 /* compatibility with non-clang compilers */
  99 #endif
 100
 101 #if __has_builtin(__builtin_assume_aligned) || !defined(__clang__)
 102 #define HAS_ASSUME_ALIGNED
 103 #endif
 104
 105 #ifndef __has_attribute
 106 #define __has_attribute(x) 0 /* compatibility with older GCC */
 107 #endif
 108
 109 #if defined(__SANITIZE_ADDRESS__) || __has_feature(address_sanitizer)
 110 # define QEMU_SANITIZE_ADDRESS 1
 111 #endif
 112
 113 #if defined(__SANITIZE_THREAD__) || __has_feature(thread_sanitizer)
 114 # define QEMU_SANITIZE_THREAD 1
 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  * In most cases, normal "fallthrough" comments are good enough for
 167  * switch-case statements, but sometimes the compiler has problems
 168  * with those. In that case you can use QEMU_FALLTHROUGH instead.
 169  */
 170 #if __has_attribute(fallthrough)
 171 # define QEMU_FALLTHROUGH __attribute__((fallthrough))
 172 #else
 173 # define QEMU_FALLTHROUGH do {} while (0) /* fallthrough */
 174 #endif
 175
 176 #ifdef CONFIG_CFI
 177 /*
 178  * If CFI is enabled, use an attribute to disable cfi-icall on the following
 179  * function
 180  */
 181 #define QEMU_DISABLE_CFI __attribute__((no_sanitize("cfi-icall")))
 182 #else
 183 /* If CFI is not enabled, use an empty define to not change the behavior */
 184 #define QEMU_DISABLE_CFI
 185 #endif
 186
 187 #endif /* COMPILER_H */