include/qemu/compiler.h - qemu - Git at Google

 /* compiler.h: macros to abstract away compiler specifics
  *
  * This work is licensed under the terms of the GNU GPL, version 2 or later.
  * See the COPYING file in the top-level directory.
  */

 #ifndef COMPILER_H
 #define COMPILER_H

 #define HOST_BIG_ENDIAN (__BYTE_ORDER__ == __ORDER_BIG_ENDIAN__)

 /* HOST_LONG_BITS is the size of a native pointer in bits. */
 #define HOST_LONG_BITS (__SIZEOF_POINTER__ * 8)

 #if defined __clang_analyzer__ || defined __COVERITY__
 #define QEMU_STATIC_ANALYSIS 1
 #endif

 #ifdef __cplusplus
 #define QEMU_EXTERN_C extern "C"
 #else
 #define QEMU_EXTERN_C extern
 #endif

 #if defined(_WIN32) && (defined(__x86_64__) || defined(__i386__))
 # define QEMU_PACKED __attribute__((gcc_struct, packed))
 #else
 # define QEMU_PACKED __attribute__((packed))
 #endif

 #define QEMU_ALIGNED(X) __attribute__((aligned(X)))

 #ifndef glue
 #define xglue(x, y) x ## y
 #define glue(x, y) xglue(x, y)
 #define stringify(s) tostring(s)
 #define tostring(s) #s
 #endif

 /* Expands into an identifier stemN, where N is another number each time */
 #define MAKE_IDENTFIER(stem) glue(stem, __COUNTER__)

 #ifndef likely
 #define likely(x)   __builtin_expect(!!(x), 1)
 #define unlikely(x)   __builtin_expect(!!(x), 0)
 #endif

 #ifndef container_of
 #define container_of(ptr, type, member) ({                      \
         const typeof(((type *) 0)->member) *__mptr = (ptr);     \
         (type *) ((char *) __mptr - offsetof(type, member));})
 #endif

 #define sizeof_field(type, field) sizeof(((type *)0)->field)

 /*
  * Calculate the number of bytes up to and including the given 'field' of
  * 'container'.
  */
 #define endof(container, field) \
     (offsetof(container, field) + sizeof_field(container, field))

 /* Convert from a base type to a parent type, with compile time checking.  */
 #define DO_UPCAST(type, field, dev) ( __extension__ ( { \
     char __attribute__((unused)) offset_must_be_zero[ \
         -offsetof(type, field)]; \
     container_of(dev, type, field);}))

 #define typeof_field(type, field) typeof(((type *)0)->field)
 #define type_check(t1,t2) ((t1*)0 - (t2*)0)

 #define QEMU_BUILD_BUG_ON_STRUCT(x) \
     struct { \
         int:(x) ? -1 : 1; \
     }

 #define QEMU_BUILD_BUG_MSG(x, msg) _Static_assert(!(x), msg)

 #define QEMU_BUILD_BUG_ON(x) QEMU_BUILD_BUG_MSG(x, "not expecting: " #x)

 #define QEMU_BUILD_BUG_ON_ZERO(x) (sizeof(QEMU_BUILD_BUG_ON_STRUCT(x)) - \
                                    sizeof(QEMU_BUILD_BUG_ON_STRUCT(x)))

 #if !defined(__clang__) && defined(_WIN32)
 /*
  * Map __printf__ to __gnu_printf__ because we want standard format strings even
  * when MinGW or GLib include files use __printf__.
  */
 # define __printf__ __gnu_printf__
 #endif

 #ifndef __has_warning
 #define __has_warning(x) 0 /* compatibility with non-clang compilers */
 #endif

 #ifndef __has_feature
 #define __has_feature(x) 0 /* compatibility with non-clang compilers */
 #endif

 #ifndef __has_builtin
 #define __has_builtin(x) 0 /* compatibility with non-clang compilers */
 #endif

 #if __has_builtin(__builtin_assume_aligned) || !defined(__clang__)
 #define HAS_ASSUME_ALIGNED
 #endif

 #ifndef __has_attribute
 #define __has_attribute(x) 0 /* compatibility with older GCC */
 #endif

 #if defined(__SANITIZE_ADDRESS__) || __has_feature(address_sanitizer)
 # define QEMU_SANITIZE_ADDRESS 1
 #endif

 #if defined(__SANITIZE_THREAD__) || __has_feature(thread_sanitizer)
 # define QEMU_SANITIZE_THREAD 1
 #endif

 /*
  * GCC doesn't provide __has_attribute() until GCC 5, but we know all the GCC
  * versions we support have the "flatten" attribute. Clang may not have the
  * "flatten" attribute but always has __has_attribute() to check for it.
  */
 #if __has_attribute(flatten) || !defined(__clang__)
 # define QEMU_FLATTEN __attribute__((flatten))
 #else
 # define QEMU_FLATTEN
 #endif

 /*
  * If __attribute__((error)) is present, use it to produce an error at
  * compile time.  Otherwise, one must wait for the linker to diagnose
  * the missing symbol.
  */
 #if __has_attribute(error)
 # define QEMU_ERROR(X) __attribute__((error(X)))
 #else
 # define QEMU_ERROR(X)
 #endif

 /*
  * The nonstring variable attribute specifies that an object or member
  * declaration with type array of char or pointer to char is intended
  * to store character arrays that do not necessarily contain a terminating
  * NUL character. This is useful in detecting uses of such arrays or pointers
  * with functions that expect NUL-terminated strings, and to avoid warnings
  * when such an array or pointer is used as an argument to a bounded string
  * manipulation function such as strncpy.
  */
 #if __has_attribute(nonstring)
 # define QEMU_NONSTRING __attribute__((nonstring))
 #else
 # define QEMU_NONSTRING
 #endif

 /*
  * Forced inlining may be desired to encourage constant propagation
  * of function parameters.  However, it can also make debugging harder,
  * so disable it for a non-optimizing build.
  */
 #if defined(__OPTIMIZE__)
 #define QEMU_ALWAYS_INLINE  __attribute__((always_inline))
 #else
 #define QEMU_ALWAYS_INLINE
 #endif

 /**
  * In most cases, normal "fallthrough" comments are good enough for
  * switch-case statements, but sometimes the compiler has problems
  * with those. In that case you can use QEMU_FALLTHROUGH instead.
  */
 #if __has_attribute(fallthrough)
 # define QEMU_FALLTHROUGH __attribute__((fallthrough))
 #else
 # define QEMU_FALLTHROUGH do {} while (0) /* fallthrough */
 #endif

 #ifdef CONFIG_CFI
 /*
  * If CFI is enabled, use an attribute to disable cfi-icall on the following
  * function
  */
 #define QEMU_DISABLE_CFI __attribute__((no_sanitize("cfi-icall")))
 #else
 /* If CFI is not enabled, use an empty define to not change the behavior */
 #define QEMU_DISABLE_CFI
 #endif

 /*
  * Apple clang version 14 has a bug in its __builtin_subcll(); define
  * BUILTIN_SUBCLL_BROKEN for the offending versions so we can avoid it.
  * When a version of Apple clang which has this bug fixed is released
  * we can add an upper bound to this check.
  * See https://gitlab.com/qemu-project/qemu/-/issues/1631
  * and https://gitlab.com/qemu-project/qemu/-/issues/1659 for details.
  * The bug never made it into any upstream LLVM releases, only Apple ones.
  */
 #if defined(__apple_build_version__) && __clang_major__ >= 14
 #define BUILTIN_SUBCLL_BROKEN
 #endif

 #if __has_attribute(annotate)
 #define QEMU_ANNOTATE(x) __attribute__((annotate(x)))
 #else
 #define QEMU_ANNOTATE(x)
 #endif

 #if __has_attribute(used)
 # define QEMU_USED __attribute__((used))
 #else
 # define QEMU_USED
 #endif

 /*
  * Ugly CPP trick that is like "defined FOO", but also works in C
  * code.  Useful to replace #ifdef with "if" statements; assumes
  * the symbol was defined with Meson's "config.set()", so it is empty
  * if defined.
  */
 #define IS_ENABLED(x)                  IS_EMPTY(x)

 #define IS_EMPTY_JUNK_                 junk,
 #define IS_EMPTY(value)                IS_EMPTY_(IS_EMPTY_JUNK_##value)

 /* Expands to either SECOND_ARG(junk, 1, 0) or SECOND_ARG(IS_EMPTY_JUNK_CONFIG_FOO 1, 0)  */
 #define SECOND_ARG(first, second, ...) second
 #define IS_EMPTY_(junk_maybecomma)     SECOND_ARG(junk_maybecomma 1, 0)

 #endif /* COMPILER_H */
	/* compiler.h: macros to abstract away compiler specifics
	*
	* This work is licensed under the terms of the GNU GPL, version 2 or later.
	* See the COPYING file in the top-level directory.
	*/

	#ifndef COMPILER_H
	#define COMPILER_H

	#define HOST_BIG_ENDIAN (__BYTE_ORDER__ == __ORDER_BIG_ENDIAN__)

	/* HOST_LONG_BITS is the size of a native pointer in bits. */
	#define HOST_LONG_BITS (__SIZEOF_POINTER__ * 8)

	#if defined __clang_analyzer__ \|\| defined __COVERITY__
	#define QEMU_STATIC_ANALYSIS 1
	#endif

	#ifdef __cplusplus
	#define QEMU_EXTERN_C extern "C"
	#else
	#define QEMU_EXTERN_C extern
	#endif

	#if defined(_WIN32) && (defined(__x86_64__) \|\| defined(__i386__))
	# define QEMU_PACKED __attribute__((gcc_struct, packed))
	#else
	# define QEMU_PACKED __attribute__((packed))
	#endif

	#define QEMU_ALIGNED(X) __attribute__((aligned(X)))

	#ifndef glue
	#define xglue(x, y) x ## y
	#define glue(x, y) xglue(x, y)
	#define stringify(s) tostring(s)
	#define tostring(s) #s
	#endif

	/* Expands into an identifier stemN, where N is another number each time */
	#define MAKE_IDENTFIER(stem) glue(stem, __COUNTER__)

	#ifndef likely
	#define likely(x) __builtin_expect(!!(x), 1)
	#define unlikely(x) __builtin_expect(!!(x), 0)
	#endif

	#ifndef container_of
	#define container_of(ptr, type, member) ({ \
	const typeof(((type ) 0)->member) __mptr = (ptr); \
	(type ) ((char ) __mptr - offsetof(type, member));})
	#endif

	#define sizeof_field(type, field) sizeof(((type *)0)->field)

	/*
	* Calculate the number of bytes up to and including the given 'field' of
	* 'container'.
	*/
	#define endof(container, field) \
	(offsetof(container, field) + sizeof_field(container, field))

	/* Convert from a base type to a parent type, with compile time checking. */
	#define DO_UPCAST(type, field, dev) ( __extension__ ( { \
	char __attribute__((unused)) offset_must_be_zero[ \
	-offsetof(type, field)]; \
	container_of(dev, type, field);}))

	#define typeof_field(type, field) typeof(((type *)0)->field)
	#define type_check(t1,t2) ((t1)0 - (t2)0)

	#define QEMU_BUILD_BUG_ON_STRUCT(x) \
	struct { \
	int:(x) ? -1 : 1; \
	}

	#define QEMU_BUILD_BUG_MSG(x, msg) _Static_assert(!(x), msg)

	#define QEMU_BUILD_BUG_ON(x) QEMU_BUILD_BUG_MSG(x, "not expecting: " #x)

	#define QEMU_BUILD_BUG_ON_ZERO(x) (sizeof(QEMU_BUILD_BUG_ON_STRUCT(x)) - \
	sizeof(QEMU_BUILD_BUG_ON_STRUCT(x)))

	#if !defined(__clang__) && defined(_WIN32)
	/*
	* Map __printf__ to __gnu_printf__ because we want standard format strings even
	* when MinGW or GLib include files use __printf__.
	*/
	# define __printf__ __gnu_printf__
	#endif

	#ifndef __has_warning
	#define __has_warning(x) 0 /* compatibility with non-clang compilers */
	#endif

	#ifndef __has_feature
	#define __has_feature(x) 0 /* compatibility with non-clang compilers */
	#endif

	#ifndef __has_builtin
	#define __has_builtin(x) 0 /* compatibility with non-clang compilers */
	#endif

	#if __has_builtin(__builtin_assume_aligned) \|\| !defined(__clang__)
	#define HAS_ASSUME_ALIGNED
	#endif

	#ifndef __has_attribute
	#define __has_attribute(x) 0 /* compatibility with older GCC */
	#endif

	#if defined(__SANITIZE_ADDRESS__) \|\| __has_feature(address_sanitizer)
	# define QEMU_SANITIZE_ADDRESS 1
	#endif

	#if defined(__SANITIZE_THREAD__) \|\| __has_feature(thread_sanitizer)
	# define QEMU_SANITIZE_THREAD 1
	#endif

	/*
	* GCC doesn't provide __has_attribute() until GCC 5, but we know all the GCC
	* versions we support have the "flatten" attribute. Clang may not have the
	* "flatten" attribute but always has __has_attribute() to check for it.
	*/
	#if __has_attribute(flatten) \|\| !defined(__clang__)
	# define QEMU_FLATTEN __attribute__((flatten))
	#else
	# define QEMU_FLATTEN
	#endif

	/*
	* If __attribute__((error)) is present, use it to produce an error at
	* compile time. Otherwise, one must wait for the linker to diagnose
	* the missing symbol.
	*/
	#if __has_attribute(error)
	# define QEMU_ERROR(X) __attribute__((error(X)))
	#else
	# define QEMU_ERROR(X)
	#endif

	/*
	* The nonstring variable attribute specifies that an object or member
	* declaration with type array of char or pointer to char is intended
	* to store character arrays that do not necessarily contain a terminating
	* NUL character. This is useful in detecting uses of such arrays or pointers
	* with functions that expect NUL-terminated strings, and to avoid warnings
	* when such an array or pointer is used as an argument to a bounded string
	* manipulation function such as strncpy.
	*/
	#if __has_attribute(nonstring)
	# define QEMU_NONSTRING __attribute__((nonstring))
	#else
	# define QEMU_NONSTRING
	#endif

	/*
	* Forced inlining may be desired to encourage constant propagation
	* of function parameters. However, it can also make debugging harder,
	* so disable it for a non-optimizing build.
	*/
	#if defined(__OPTIMIZE__)
	#define QEMU_ALWAYS_INLINE __attribute__((always_inline))
	#else
	#define QEMU_ALWAYS_INLINE
	#endif

	/**
	* In most cases, normal "fallthrough" comments are good enough for
	* switch-case statements, but sometimes the compiler has problems
	* with those. In that case you can use QEMU_FALLTHROUGH instead.
	*/
	#if __has_attribute(fallthrough)
	# define QEMU_FALLTHROUGH __attribute__((fallthrough))
	#else
	# define QEMU_FALLTHROUGH do {} while (0) /* fallthrough */
	#endif

	#ifdef CONFIG_CFI
	/*
	* If CFI is enabled, use an attribute to disable cfi-icall on the following
	* function
	*/
	#define QEMU_DISABLE_CFI __attribute__((no_sanitize("cfi-icall")))
	#else
	/* If CFI is not enabled, use an empty define to not change the behavior */
	#define QEMU_DISABLE_CFI
	#endif

	/*
	* Apple clang version 14 has a bug in its __builtin_subcll(); define
	* BUILTIN_SUBCLL_BROKEN for the offending versions so we can avoid it.
	* When a version of Apple clang which has this bug fixed is released
	* we can add an upper bound to this check.
	* See https://gitlab.com/qemu-project/qemu/-/issues/1631
	* and https://gitlab.com/qemu-project/qemu/-/issues/1659 for details.
	* The bug never made it into any upstream LLVM releases, only Apple ones.
	*/
	#if defined(__apple_build_version__) && __clang_major__ >= 14
	#define BUILTIN_SUBCLL_BROKEN
	#endif

	#if __has_attribute(annotate)
	#define QEMU_ANNOTATE(x) __attribute__((annotate(x)))
	#else
	#define QEMU_ANNOTATE(x)
	#endif

	#if __has_attribute(used)
	# define QEMU_USED __attribute__((used))
	#else
	# define QEMU_USED
	#endif

	/*
	* Ugly CPP trick that is like "defined FOO", but also works in C
	* code. Useful to replace #ifdef with "if" statements; assumes
	* the symbol was defined with Meson's "config.set()", so it is empty
	* if defined.
	*/
	#define IS_ENABLED(x) IS_EMPTY(x)

	#define IS_EMPTY_JUNK_ junk,
	#define IS_EMPTY(value) IS_EMPTY_(IS_EMPTY_JUNK_##value)

	/* Expands to either SECOND_ARG(junk, 1, 0) or SECOND_ARG(IS_EMPTY_JUNK_CONFIG_FOO 1, 0) */
	#define SECOND_ARG(first, second, ...) second
	#define IS_EMPTY_(junk_maybecomma) SECOND_ARG(junk_maybecomma 1, 0)

	#endif /* COMPILER_H */