LXR qemu/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 */
 188