Provide a symbol that can always be used to signal an error, regardless of optimization. Usage of this should be protected by e.g. __builtin_constant_p, which guards for optimization. Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
249 lines
8.4 KiB
C
249 lines
8.4 KiB
C
/* 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
|
|
|
|
#if defined __clang_analyzer__ || defined __COVERITY__
|
|
#define QEMU_STATIC_ANALYSIS 1
|
|
#endif
|
|
|
|
#define QEMU_NORETURN __attribute__ ((__noreturn__))
|
|
|
|
#define QEMU_WARN_UNUSED_RESULT __attribute__((warn_unused_result))
|
|
|
|
#define QEMU_SENTINEL __attribute__((sentinel))
|
|
|
|
#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
|
|
|
|
#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; \
|
|
}
|
|
|
|
/* QEMU_BUILD_BUG_MSG() emits the message given if _Static_assert is
|
|
* supported; otherwise, it will be omitted from the compiler error
|
|
* message (but as it remains present in the source code, it can still
|
|
* be useful when debugging). */
|
|
#if defined(CONFIG_STATIC_ASSERT)
|
|
#define QEMU_BUILD_BUG_MSG(x, msg) _Static_assert(!(x), msg)
|
|
#elif defined(__COUNTER__)
|
|
#define QEMU_BUILD_BUG_MSG(x, msg) typedef QEMU_BUILD_BUG_ON_STRUCT(x) \
|
|
glue(qemu_build_bug_on__, __COUNTER__) __attribute__((unused))
|
|
#else
|
|
#define QEMU_BUILD_BUG_MSG(x, msg)
|
|
#endif
|
|
|
|
#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__)
|
|
/* clang doesn't support gnu_printf, so use printf. */
|
|
# define GCC_FMT_ATTR(n, m) __attribute__((format(printf, n, m)))
|
|
#else
|
|
/* Use gnu_printf (qemu uses standard format strings). */
|
|
# define GCC_FMT_ATTR(n, m) __attribute__((format(gnu_printf, n, m)))
|
|
# if 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
|
|
#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
|
|
|
|
/*
|
|
* 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
|
|
|
|
/* Implement C11 _Generic via GCC builtins. Example:
|
|
*
|
|
* QEMU_GENERIC(x, (float, sinf), (long double, sinl), sin) (x)
|
|
*
|
|
* The first argument is the discriminator. The last is the default value.
|
|
* The middle ones are tuples in "(type, expansion)" format.
|
|
*/
|
|
|
|
/* First, find out the number of generic cases. */
|
|
#define QEMU_GENERIC(x, ...) \
|
|
QEMU_GENERIC_(typeof(x), __VA_ARGS__, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0)
|
|
|
|
/* There will be extra arguments, but they are not used. */
|
|
#define QEMU_GENERIC_(x, a0, a1, a2, a3, a4, a5, a6, a7, a8, a9, count, ...) \
|
|
QEMU_GENERIC##count(x, a0, a1, a2, a3, a4, a5, a6, a7, a8, a9)
|
|
|
|
/* Two more helper macros, this time to extract items from a parenthesized
|
|
* list.
|
|
*/
|
|
#define QEMU_FIRST_(a, b) a
|
|
#define QEMU_SECOND_(a, b) b
|
|
|
|
/* ... and a final one for the common part of the "recursion". */
|
|
#define QEMU_GENERIC_IF(x, type_then, else_) \
|
|
__builtin_choose_expr(__builtin_types_compatible_p(x, \
|
|
QEMU_FIRST_ type_then), \
|
|
QEMU_SECOND_ type_then, else_)
|
|
|
|
/* CPP poor man's "recursion". */
|
|
#define QEMU_GENERIC1(x, a0, ...) (a0)
|
|
#define QEMU_GENERIC2(x, a0, ...) QEMU_GENERIC_IF(x, a0, QEMU_GENERIC1(x, __VA_ARGS__))
|
|
#define QEMU_GENERIC3(x, a0, ...) QEMU_GENERIC_IF(x, a0, QEMU_GENERIC2(x, __VA_ARGS__))
|
|
#define QEMU_GENERIC4(x, a0, ...) QEMU_GENERIC_IF(x, a0, QEMU_GENERIC3(x, __VA_ARGS__))
|
|
#define QEMU_GENERIC5(x, a0, ...) QEMU_GENERIC_IF(x, a0, QEMU_GENERIC4(x, __VA_ARGS__))
|
|
#define QEMU_GENERIC6(x, a0, ...) QEMU_GENERIC_IF(x, a0, QEMU_GENERIC5(x, __VA_ARGS__))
|
|
#define QEMU_GENERIC7(x, a0, ...) QEMU_GENERIC_IF(x, a0, QEMU_GENERIC6(x, __VA_ARGS__))
|
|
#define QEMU_GENERIC8(x, a0, ...) QEMU_GENERIC_IF(x, a0, QEMU_GENERIC7(x, __VA_ARGS__))
|
|
#define QEMU_GENERIC9(x, a0, ...) QEMU_GENERIC_IF(x, a0, QEMU_GENERIC8(x, __VA_ARGS__))
|
|
#define QEMU_GENERIC10(x, a0, ...) QEMU_GENERIC_IF(x, a0, QEMU_GENERIC9(x, __VA_ARGS__))
|
|
|
|
/**
|
|
* qemu_build_not_reached()
|
|
*
|
|
* The compiler, during optimization, is expected to prove that a call
|
|
* to this function cannot be reached and remove it. If the compiler
|
|
* supports QEMU_ERROR, this will be reported at compile time; otherwise
|
|
* this will be reported at link time due to the missing symbol.
|
|
*/
|
|
extern void QEMU_NORETURN QEMU_ERROR("code path is reachable")
|
|
qemu_build_not_reached_always(void);
|
|
#if defined(__OPTIMIZE__) && !defined(__NO_INLINE__)
|
|
#define qemu_build_not_reached() qemu_build_not_reached_always()
|
|
#else
|
|
#define qemu_build_not_reached() g_assert_not_reached()
|
|
#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
|
|
|
|
#endif /* COMPILER_H */
|