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/* Convert from a base type to a parent type, with compile time checking.  */
  68#ifdef __GNUC__
  69#define DO_UPCAST(type, field, dev) ( __extension__ ( { \
  70    char __attribute__((unused)) offset_must_be_zero[ \
  71        -offsetof(type, field)]; \
  72    container_of(dev, type, field);}))
  73#else
  74#define DO_UPCAST(type, field, dev) container_of(dev, type, field)
  75#endif
  76
  77#define typeof_field(type, field) typeof(((type *)0)->field)
  78#define type_check(t1,t2) ((t1*)0 - (t2*)0)
  79
  80#define QEMU_BUILD_BUG_ON_STRUCT(x) \
  81    struct { \
  82        int:(x) ? -1 : 1; \
  83    }
  84
  85/* QEMU_BUILD_BUG_MSG() emits the message given if _Static_assert is
  86 * supported; otherwise, it will be omitted from the compiler error
  87 * message (but as it remains present in the source code, it can still
  88 * be useful when debugging). */
  89#if defined(CONFIG_STATIC_ASSERT)
  90#define QEMU_BUILD_BUG_MSG(x, msg) _Static_assert(!(x), msg)
  91#elif defined(__COUNTER__)
  92#define QEMU_BUILD_BUG_MSG(x, msg) typedef QEMU_BUILD_BUG_ON_STRUCT(x) \
  93    glue(qemu_build_bug_on__, __COUNTER__) __attribute__((unused))
  94#else
  95#define QEMU_BUILD_BUG_MSG(x, msg)
  96#endif
  97
  98#define QEMU_BUILD_BUG_ON(x) QEMU_BUILD_BUG_MSG(x, "not expecting: " #x)
  99
 100#define QEMU_BUILD_BUG_ON_ZERO(x) (sizeof(QEMU_BUILD_BUG_ON_STRUCT(x)) - \
 101                                   sizeof(QEMU_BUILD_BUG_ON_STRUCT(x)))
 102
 103#if defined __GNUC__
 104# if !QEMU_GNUC_PREREQ(4, 4)
 105   /* gcc versions before 4.4.x don't support gnu_printf, so use printf. */
 106#  define GCC_FMT_ATTR(n, m) __attribute__((format(printf, n, m)))
 107# else
 108   /* Use gnu_printf when supported (qemu uses standard format strings). */
 109#  define GCC_FMT_ATTR(n, m) __attribute__((format(gnu_printf, n, m)))
 110#  if defined(_WIN32)
 111    /* Map __printf__ to __gnu_printf__ because we want standard format strings
 112     * even when MinGW or GLib include files use __printf__. */
 113#   define __printf__ __gnu_printf__
 114#  endif
 115# endif
 116#else
 117#define GCC_FMT_ATTR(n, m)
 118#endif
 119
 120#ifndef __has_feature
 121#define __has_feature(x) 0 /* compatibility with non-clang compilers */
 122#endif
 123/* Implement C11 _Generic via GCC builtins.  Example:
 124 *
 125 *    QEMU_GENERIC(x, (float, sinf), (long double, sinl), sin) (x)
 126 *
 127 * The first argument is the discriminator.  The last is the default value.
 128 * The middle ones are tuples in "(type, expansion)" format.
 129 */
 130
 131/* First, find out the number of generic cases.  */
 132#define QEMU_GENERIC(x, ...) \
 133    QEMU_GENERIC_(typeof(x), __VA_ARGS__, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0)
 134
 135/* There will be extra arguments, but they are not used.  */
 136#define QEMU_GENERIC_(x, a0, a1, a2, a3, a4, a5, a6, a7, a8, a9, count, ...) \
 137    QEMU_GENERIC##count(x, a0, a1, a2, a3, a4, a5, a6, a7, a8, a9)
 138
 139/* Two more helper macros, this time to extract items from a parenthesized
 140 * list.
 141 */
 142#define QEMU_FIRST_(a, b) a
 143#define QEMU_SECOND_(a, b) b
 144
 145/* ... and a final one for the common part of the "recursion".  */
 146#define QEMU_GENERIC_IF(x, type_then, else_)                                   \
 147    __builtin_choose_expr(__builtin_types_compatible_p(x,                      \
 148                                                       QEMU_FIRST_ type_then), \
 149                          QEMU_SECOND_ type_then, else_)
 150
 151/* CPP poor man's "recursion".  */
 152#define QEMU_GENERIC1(x, a0, ...) (a0)
 153#define QEMU_GENERIC2(x, a0, ...) QEMU_GENERIC_IF(x, a0, QEMU_GENERIC1(x, __VA_ARGS__))
 154#define QEMU_GENERIC3(x, a0, ...) QEMU_GENERIC_IF(x, a0, QEMU_GENERIC2(x, __VA_ARGS__))
 155#define QEMU_GENERIC4(x, a0, ...) QEMU_GENERIC_IF(x, a0, QEMU_GENERIC3(x, __VA_ARGS__))
 156#define QEMU_GENERIC5(x, a0, ...) QEMU_GENERIC_IF(x, a0, QEMU_GENERIC4(x, __VA_ARGS__))
 157#define QEMU_GENERIC6(x, a0, ...) QEMU_GENERIC_IF(x, a0, QEMU_GENERIC5(x, __VA_ARGS__))
 158#define QEMU_GENERIC7(x, a0, ...) QEMU_GENERIC_IF(x, a0, QEMU_GENERIC6(x, __VA_ARGS__))
 159#define QEMU_GENERIC8(x, a0, ...) QEMU_GENERIC_IF(x, a0, QEMU_GENERIC7(x, __VA_ARGS__))
 160#define QEMU_GENERIC9(x, a0, ...) QEMU_GENERIC_IF(x, a0, QEMU_GENERIC8(x, __VA_ARGS__))
 161#define QEMU_GENERIC10(x, a0, ...) QEMU_GENERIC_IF(x, a0, QEMU_GENERIC9(x, __VA_ARGS__))
 162
 163#endif /* COMPILER_H */
 164