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#if defined __clang_analyzer__ || defined __COVERITY__
  11#define QEMU_STATIC_ANALYSIS 1
  12#endif
  13
  14/*----------------------------------------------------------------------------
  15| The macro QEMU_GNUC_PREREQ tests for minimum version of the GNU C compiler.
  16| The code is a copy of SOFTFLOAT_GNUC_PREREQ, see softfloat-macros.h.
  17*----------------------------------------------------------------------------*/
  18#if defined(__GNUC__) && defined(__GNUC_MINOR__)
  19# define QEMU_GNUC_PREREQ(maj, min) \
  20         ((__GNUC__ << 16) + __GNUC_MINOR__ >= ((maj) << 16) + (min))
  21#else
  22# define QEMU_GNUC_PREREQ(maj, min) 0
  23#endif
  24
  25#define QEMU_NORETURN __attribute__ ((__noreturn__))
  26
  27#define QEMU_WARN_UNUSED_RESULT __attribute__((warn_unused_result))
  28
  29#define QEMU_SENTINEL __attribute__((sentinel))
  30
  31#if QEMU_GNUC_PREREQ(4, 3)
  32#define QEMU_ARTIFICIAL __attribute__((always_inline, artificial))
  33#else
  34#define QEMU_ARTIFICIAL
  35#endif
  36
  37#if defined(_WIN32)
  38# define QEMU_PACKED __attribute__((gcc_struct, packed))
  39#else
  40# define QEMU_PACKED __attribute__((packed))
  41#endif
  42
  43#define QEMU_ALIGNED(X) __attribute__((aligned(X)))
  44
  45#ifndef glue
  46#define xglue(x, y) x ## y
  47#define glue(x, y) xglue(x, y)
  48#define stringify(s)    tostring(s)
  49#define tostring(s)     #s
  50#endif
  51
  52#ifndef likely
  53#if __GNUC__ < 3
  54#define __builtin_expect(x, n) (x)
  55#endif
  56
  57#define likely(x)   __builtin_expect(!!(x), 1)
  58#define unlikely(x)   __builtin_expect(!!(x), 0)
  59#endif
  60
  61#ifndef container_of
  62#define container_of(ptr, type, member) ({                      \
  63        const typeof(((type *) 0)->member) *__mptr = (ptr);     \
  64        (type *) ((char *) __mptr - offsetof(type, member));})
  65#endif
  66
  67#define sizeof_field(type, field) sizeof(((type *)0)->field)
  68
  69/* Convert from a base type to a parent type, with compile time checking.  */
  70#ifdef __GNUC__
  71#define DO_UPCAST(type, field, dev) ( __extension__ ( { \
  72    char __attribute__((unused)) offset_must_be_zero[ \
  73        -offsetof(type, field)]; \
  74    container_of(dev, type, field);}))
  75#else
  76#define DO_UPCAST(type, field, dev) container_of(dev, type, field)
  77#endif
  78
  79#define typeof_field(type, field) typeof(((type *)0)->field)
  80#define type_check(t1,t2) ((t1*)0 - (t2*)0)
  81
  82#define QEMU_BUILD_BUG_ON_STRUCT(x) \
  83    struct { \
  84        int:(x) ? -1 : 1; \
  85    }
  86
  87/* QEMU_BUILD_BUG_MSG() emits the message given if _Static_assert is
  88 * supported; otherwise, it will be omitted from the compiler error
  89 * message (but as it remains present in the source code, it can still
  90 * be useful when debugging). */
  91#if defined(CONFIG_STATIC_ASSERT)
  92#define QEMU_BUILD_BUG_MSG(x, msg) _Static_assert(!(x), msg)
  93#elif defined(__COUNTER__)
  94#define QEMU_BUILD_BUG_MSG(x, msg) typedef QEMU_BUILD_BUG_ON_STRUCT(x) \
  95    glue(qemu_build_bug_on__, __COUNTER__) __attribute__((unused))
  96#else
  97#define QEMU_BUILD_BUG_MSG(x, msg)
  98#endif
  99
 100#define QEMU_BUILD_BUG_ON(x) QEMU_BUILD_BUG_MSG(x, "not expecting: " #x)
 101
 102#define QEMU_BUILD_BUG_ON_ZERO(x) (sizeof(QEMU_BUILD_BUG_ON_STRUCT(x)) - \
 103                                   sizeof(QEMU_BUILD_BUG_ON_STRUCT(x)))
 104
 105#if defined __GNUC__
 106# if !QEMU_GNUC_PREREQ(4, 4)
 107   /* gcc versions before 4.4.x don't support gnu_printf, so use printf. */
 108#  define GCC_FMT_ATTR(n, m) __attribute__((format(printf, n, m)))
 109# else
 110   /* Use gnu_printf when supported (qemu uses standard format strings). */
 111#  define GCC_FMT_ATTR(n, m) __attribute__((format(gnu_printf, n, m)))
 112#  if defined(_WIN32)
 113    /* Map __printf__ to __gnu_printf__ because we want standard format strings
 114     * even when MinGW or GLib include files use __printf__. */
 115#   define __printf__ __gnu_printf__
 116#  endif
 117# endif
 118#else
 119#define GCC_FMT_ATTR(n, m)
 120#endif
 121
 122#ifndef __has_feature
 123#define __has_feature(x) 0 /* compatibility with non-clang compilers */
 124#endif
 125
 126#ifndef __has_builtin
 127#define __has_builtin(x) 0 /* compatibility with non-clang compilers */
 128#endif
 129
 130#if __has_builtin(__builtin_assume_aligned) || QEMU_GNUC_PREREQ(4, 7)
 131#define HAS_ASSUME_ALIGNED
 132#endif
 133
 134#ifndef __has_attribute
 135#define __has_attribute(x) 0 /* compatibility with older GCC */
 136#endif
 137
 138/*
 139 * GCC doesn't provide __has_attribute() until GCC 5, but we know all the GCC
 140 * versions we support have the "flatten" attribute. Clang may not have the
 141 * "flatten" attribute but always has __has_attribute() to check for it.
 142 */
 143#if __has_attribute(flatten) || !defined(__clang__)
 144# define QEMU_FLATTEN __attribute__((flatten))
 145#else
 146# define QEMU_FLATTEN
 147#endif
 148
 149/*
 150 * If __attribute__((error)) is present, use it to produce an error at
 151 * compile time.  Otherwise, one must wait for the linker to diagnose
 152 * the missing symbol.
 153 */
 154#if __has_attribute(error)
 155# define QEMU_ERROR(X) __attribute__((error(X)))
 156#else
 157# define QEMU_ERROR(X)
 158#endif
 159
 160/* Implement C11 _Generic via GCC builtins.  Example:
 161 *
 162 *    QEMU_GENERIC(x, (float, sinf), (long double, sinl), sin) (x)
 163 *
 164 * The first argument is the discriminator.  The last is the default value.
 165 * The middle ones are tuples in "(type, expansion)" format.
 166 */
 167
 168/* First, find out the number of generic cases.  */
 169#define QEMU_GENERIC(x, ...) \
 170    QEMU_GENERIC_(typeof(x), __VA_ARGS__, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0)
 171
 172/* There will be extra arguments, but they are not used.  */
 173#define QEMU_GENERIC_(x, a0, a1, a2, a3, a4, a5, a6, a7, a8, a9, count, ...) \
 174    QEMU_GENERIC##count(x, a0, a1, a2, a3, a4, a5, a6, a7, a8, a9)
 175
 176/* Two more helper macros, this time to extract items from a parenthesized
 177 * list.
 178 */
 179#define QEMU_FIRST_(a, b) a
 180#define QEMU_SECOND_(a, b) b
 181
 182/* ... and a final one for the common part of the "recursion".  */
 183#define QEMU_GENERIC_IF(x, type_then, else_)                                   \
 184    __builtin_choose_expr(__builtin_types_compatible_p(x,                      \
 185                                                       QEMU_FIRST_ type_then), \
 186                          QEMU_SECOND_ type_then, else_)
 187
 188/* CPP poor man's "recursion".  */
 189#define QEMU_GENERIC1(x, a0, ...) (a0)
 190#define QEMU_GENERIC2(x, a0, ...) QEMU_GENERIC_IF(x, a0, QEMU_GENERIC1(x, __VA_ARGS__))
 191#define QEMU_GENERIC3(x, a0, ...) QEMU_GENERIC_IF(x, a0, QEMU_GENERIC2(x, __VA_ARGS__))
 192#define QEMU_GENERIC4(x, a0, ...) QEMU_GENERIC_IF(x, a0, QEMU_GENERIC3(x, __VA_ARGS__))
 193#define QEMU_GENERIC5(x, a0, ...) QEMU_GENERIC_IF(x, a0, QEMU_GENERIC4(x, __VA_ARGS__))
 194#define QEMU_GENERIC6(x, a0, ...) QEMU_GENERIC_IF(x, a0, QEMU_GENERIC5(x, __VA_ARGS__))
 195#define QEMU_GENERIC7(x, a0, ...) QEMU_GENERIC_IF(x, a0, QEMU_GENERIC6(x, __VA_ARGS__))
 196#define QEMU_GENERIC8(x, a0, ...) QEMU_GENERIC_IF(x, a0, QEMU_GENERIC7(x, __VA_ARGS__))
 197#define QEMU_GENERIC9(x, a0, ...) QEMU_GENERIC_IF(x, a0, QEMU_GENERIC8(x, __VA_ARGS__))
 198#define QEMU_GENERIC10(x, a0, ...) QEMU_GENERIC_IF(x, a0, QEMU_GENERIC9(x, __VA_ARGS__))
 199
 200#endif /* COMPILER_H */
 201