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 defined(_WIN32) && (defined(__x86_64__) || defined(__i386__)) 32 # define QEMU_PACKED __attribute__((gcc_struct, packed)) 33 #else 34 # define QEMU_PACKED __attribute__((packed)) 35 #endif 36 37 #define QEMU_ALIGNED(X) __attribute__((aligned(X))) 38 39 #ifndef glue 40 #define xglue(x, y) x ## y 41 #define glue(x, y) xglue(x, y) 42 #define stringify(s) tostring(s) 43 #define tostring(s) #s 44 #endif 45 46 #ifndef likely 47 #if __GNUC__ < 3 48 #define __builtin_expect(x, n) (x) 49 #endif 50 51 #define likely(x) __builtin_expect(!!(x), 1) 52 #define unlikely(x) __builtin_expect(!!(x), 0) 53 #endif 54 55 #ifndef container_of 56 #define container_of(ptr, type, member) ({ \ 57 const typeof(((type *) 0)->member) *__mptr = (ptr); \ 58 (type *) ((char *) __mptr - offsetof(type, member));}) 59 #endif 60 61 #define sizeof_field(type, field) sizeof(((type *)0)->field) 62 63 /* Convert from a base type to a parent type, with compile time checking. */ 64 #ifdef __GNUC__ 65 #define DO_UPCAST(type, field, dev) ( __extension__ ( { \ 66 char __attribute__((unused)) offset_must_be_zero[ \ 67 -offsetof(type, field)]; \ 68 container_of(dev, type, field);})) 69 #else 70 #define DO_UPCAST(type, field, dev) container_of(dev, type, field) 71 #endif 72 73 #define typeof_field(type, field) typeof(((type *)0)->field) 74 #define type_check(t1,t2) ((t1*)0 - (t2*)0) 75 76 #define QEMU_BUILD_BUG_ON_STRUCT(x) \ 77 struct { \ 78 int:(x) ? -1 : 1; \ 79 } 80 81 /* QEMU_BUILD_BUG_MSG() emits the message given if _Static_assert is 82 * supported; otherwise, it will be omitted from the compiler error 83 * message (but as it remains present in the source code, it can still 84 * be useful when debugging). */ 85 #if defined(CONFIG_STATIC_ASSERT) 86 #define QEMU_BUILD_BUG_MSG(x, msg) _Static_assert(!(x), msg) 87 #elif defined(__COUNTER__) 88 #define QEMU_BUILD_BUG_MSG(x, msg) typedef QEMU_BUILD_BUG_ON_STRUCT(x) \ 89 glue(qemu_build_bug_on__, __COUNTER__) __attribute__((unused)) 90 #else 91 #define QEMU_BUILD_BUG_MSG(x, msg) 92 #endif 93 94 #define QEMU_BUILD_BUG_ON(x) QEMU_BUILD_BUG_MSG(x, "not expecting: " #x) 95 96 #define QEMU_BUILD_BUG_ON_ZERO(x) (sizeof(QEMU_BUILD_BUG_ON_STRUCT(x)) - \ 97 sizeof(QEMU_BUILD_BUG_ON_STRUCT(x))) 98 99 #if defined __GNUC__ 100 # if !QEMU_GNUC_PREREQ(4, 4) 101 /* gcc versions before 4.4.x don't support gnu_printf, so use printf. */ 102 # define GCC_FMT_ATTR(n, m) __attribute__((format(printf, n, m))) 103 # else 104 /* Use gnu_printf when supported (qemu uses standard format strings). */ 105 # define GCC_FMT_ATTR(n, m) __attribute__((format(gnu_printf, n, m))) 106 # if defined(_WIN32) 107 /* Map __printf__ to __gnu_printf__ because we want standard format strings 108 * even when MinGW or GLib include files use __printf__. */ 109 # define __printf__ __gnu_printf__ 110 # endif 111 # endif 112 #else 113 #define GCC_FMT_ATTR(n, m) 114 #endif 115 116 #ifndef __has_warning 117 #define __has_warning(x) 0 /* compatibility with non-clang compilers */ 118 #endif 119 120 #ifndef __has_feature 121 #define __has_feature(x) 0 /* compatibility with non-clang compilers */ 122 #endif 123 124 #ifndef __has_builtin 125 #define __has_builtin(x) 0 /* compatibility with non-clang compilers */ 126 #endif 127 128 #if __has_builtin(__builtin_assume_aligned) || !defined(__clang__) 129 #define HAS_ASSUME_ALIGNED 130 #endif 131 132 #ifndef __has_attribute 133 #define __has_attribute(x) 0 /* compatibility with older GCC */ 134 #endif 135 136 /* 137 * GCC doesn't provide __has_attribute() until GCC 5, but we know all the GCC 138 * versions we support have the "flatten" attribute. Clang may not have the 139 * "flatten" attribute but always has __has_attribute() to check for it. 140 */ 141 #if __has_attribute(flatten) || !defined(__clang__) 142 # define QEMU_FLATTEN __attribute__((flatten)) 143 #else 144 # define QEMU_FLATTEN 145 #endif 146 147 /* 148 * If __attribute__((error)) is present, use it to produce an error at 149 * compile time. Otherwise, one must wait for the linker to diagnose 150 * the missing symbol. 151 */ 152 #if __has_attribute(error) 153 # define QEMU_ERROR(X) __attribute__((error(X))) 154 #else 155 # define QEMU_ERROR(X) 156 #endif 157 158 /* 159 * The nonstring variable attribute specifies that an object or member 160 * declaration with type array of char or pointer to char is intended 161 * to store character arrays that do not necessarily contain a terminating 162 * NUL character. This is useful in detecting uses of such arrays or pointers 163 * with functions that expect NUL-terminated strings, and to avoid warnings 164 * when such an array or pointer is used as an argument to a bounded string 165 * manipulation function such as strncpy. 166 */ 167 #if __has_attribute(nonstring) 168 # define QEMU_NONSTRING __attribute__((nonstring)) 169 #else 170 # define QEMU_NONSTRING 171 #endif 172 173 /* Implement C11 _Generic via GCC builtins. Example: 174 * 175 * QEMU_GENERIC(x, (float, sinf), (long double, sinl), sin) (x) 176 * 177 * The first argument is the discriminator. The last is the default value. 178 * The middle ones are tuples in "(type, expansion)" format. 179 */ 180 181 /* First, find out the number of generic cases. */ 182 #define QEMU_GENERIC(x, ...) \ 183 QEMU_GENERIC_(typeof(x), __VA_ARGS__, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0) 184 185 /* There will be extra arguments, but they are not used. */ 186 #define QEMU_GENERIC_(x, a0, a1, a2, a3, a4, a5, a6, a7, a8, a9, count, ...) \ 187 QEMU_GENERIC##count(x, a0, a1, a2, a3, a4, a5, a6, a7, a8, a9) 188 189 /* Two more helper macros, this time to extract items from a parenthesized 190 * list. 191 */ 192 #define QEMU_FIRST_(a, b) a 193 #define QEMU_SECOND_(a, b) b 194 195 /* ... and a final one for the common part of the "recursion". */ 196 #define QEMU_GENERIC_IF(x, type_then, else_) \ 197 __builtin_choose_expr(__builtin_types_compatible_p(x, \ 198 QEMU_FIRST_ type_then), \ 199 QEMU_SECOND_ type_then, else_) 200 201 /* CPP poor man's "recursion". */ 202 #define QEMU_GENERIC1(x, a0, ...) (a0) 203 #define QEMU_GENERIC2(x, a0, ...) QEMU_GENERIC_IF(x, a0, QEMU_GENERIC1(x, __VA_ARGS__)) 204 #define QEMU_GENERIC3(x, a0, ...) QEMU_GENERIC_IF(x, a0, QEMU_GENERIC2(x, __VA_ARGS__)) 205 #define QEMU_GENERIC4(x, a0, ...) QEMU_GENERIC_IF(x, a0, QEMU_GENERIC3(x, __VA_ARGS__)) 206 #define QEMU_GENERIC5(x, a0, ...) QEMU_GENERIC_IF(x, a0, QEMU_GENERIC4(x, __VA_ARGS__)) 207 #define QEMU_GENERIC6(x, a0, ...) QEMU_GENERIC_IF(x, a0, QEMU_GENERIC5(x, __VA_ARGS__)) 208 #define QEMU_GENERIC7(x, a0, ...) QEMU_GENERIC_IF(x, a0, QEMU_GENERIC6(x, __VA_ARGS__)) 209 #define QEMU_GENERIC8(x, a0, ...) QEMU_GENERIC_IF(x, a0, QEMU_GENERIC7(x, __VA_ARGS__)) 210 #define QEMU_GENERIC9(x, a0, ...) QEMU_GENERIC_IF(x, a0, QEMU_GENERIC8(x, __VA_ARGS__)) 211 #define QEMU_GENERIC10(x, a0, ...) QEMU_GENERIC_IF(x, a0, QEMU_GENERIC9(x, __VA_ARGS__)) 212 213 #endif /* COMPILER_H */ 214