_Static_assert() allows us to specify messages, and that may come in handy. Even without _Static_assert(), encouraging developers to put a helpful message next to the QEMU_BUILD_BUG_* may make debugging easier whenever it breaks. Signed-off-by: Max Reitz <mreitz@redhat.com> Message-Id: <20180224154033.29559-2-mreitz@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com> Reviewed-by: Alberto Garcia <berto@igalia.com> Signed-off-by: Eric Blake <eblake@redhat.com>
164 lines
5.8 KiB
C
164 lines
5.8 KiB
C
/* compiler.h: macros to abstract away compiler specifics
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*
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* This work is licensed under the terms of the GNU GPL, version 2 or later.
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* See the COPYING file in the top-level directory.
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*/
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#ifndef COMPILER_H
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#define COMPILER_H
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#if defined __clang_analyzer__ || defined __COVERITY__
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#define QEMU_STATIC_ANALYSIS 1
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#endif
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/*----------------------------------------------------------------------------
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| The macro QEMU_GNUC_PREREQ tests for minimum version of the GNU C compiler.
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| The code is a copy of SOFTFLOAT_GNUC_PREREQ, see softfloat-macros.h.
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*----------------------------------------------------------------------------*/
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#if defined(__GNUC__) && defined(__GNUC_MINOR__)
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# define QEMU_GNUC_PREREQ(maj, min) \
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((__GNUC__ << 16) + __GNUC_MINOR__ >= ((maj) << 16) + (min))
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#else
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# define QEMU_GNUC_PREREQ(maj, min) 0
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#endif
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#define QEMU_NORETURN __attribute__ ((__noreturn__))
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#define QEMU_WARN_UNUSED_RESULT __attribute__((warn_unused_result))
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#define QEMU_SENTINEL __attribute__((sentinel))
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#if QEMU_GNUC_PREREQ(4, 3)
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#define QEMU_ARTIFICIAL __attribute__((always_inline, artificial))
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#else
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#define QEMU_ARTIFICIAL
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#endif
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#if defined(_WIN32)
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# define QEMU_PACKED __attribute__((gcc_struct, packed))
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#else
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# define QEMU_PACKED __attribute__((packed))
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#endif
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#define QEMU_ALIGNED(X) __attribute__((aligned(X)))
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#ifndef glue
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#define xglue(x, y) x ## y
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#define glue(x, y) xglue(x, y)
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#define stringify(s) tostring(s)
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#define tostring(s) #s
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#endif
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#ifndef likely
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#if __GNUC__ < 3
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#define __builtin_expect(x, n) (x)
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#endif
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#define likely(x) __builtin_expect(!!(x), 1)
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#define unlikely(x) __builtin_expect(!!(x), 0)
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#endif
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#ifndef container_of
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#define container_of(ptr, type, member) ({ \
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const typeof(((type *) 0)->member) *__mptr = (ptr); \
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(type *) ((char *) __mptr - offsetof(type, member));})
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#endif
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/* Convert from a base type to a parent type, with compile time checking. */
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#ifdef __GNUC__
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#define DO_UPCAST(type, field, dev) ( __extension__ ( { \
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char __attribute__((unused)) offset_must_be_zero[ \
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-offsetof(type, field)]; \
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container_of(dev, type, field);}))
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#else
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#define DO_UPCAST(type, field, dev) container_of(dev, type, field)
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#endif
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#define typeof_field(type, field) typeof(((type *)0)->field)
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#define type_check(t1,t2) ((t1*)0 - (t2*)0)
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#define QEMU_BUILD_BUG_ON_STRUCT(x) \
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struct { \
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int:(x) ? -1 : 1; \
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}
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/* QEMU_BUILD_BUG_MSG() emits the message given if _Static_assert is
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* supported; otherwise, it will be omitted from the compiler error
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* message (but as it remains present in the source code, it can still
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* be useful when debugging). */
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#if defined(CONFIG_STATIC_ASSERT)
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#define QEMU_BUILD_BUG_MSG(x, msg) _Static_assert(!(x), msg)
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#elif defined(__COUNTER__)
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#define QEMU_BUILD_BUG_MSG(x, msg) typedef QEMU_BUILD_BUG_ON_STRUCT(x) \
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glue(qemu_build_bug_on__, __COUNTER__) __attribute__((unused))
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#else
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#define QEMU_BUILD_BUG_MSG(x, msg)
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#endif
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#define QEMU_BUILD_BUG_ON(x) QEMU_BUILD_BUG_MSG(x, "not expecting: " #x)
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#define QEMU_BUILD_BUG_ON_ZERO(x) (sizeof(QEMU_BUILD_BUG_ON_STRUCT(x)) - \
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sizeof(QEMU_BUILD_BUG_ON_STRUCT(x)))
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#if defined __GNUC__
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# if !QEMU_GNUC_PREREQ(4, 4)
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/* gcc versions before 4.4.x don't support gnu_printf, so use printf. */
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# define GCC_FMT_ATTR(n, m) __attribute__((format(printf, n, m)))
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# else
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/* Use gnu_printf when supported (qemu uses standard format strings). */
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# define GCC_FMT_ATTR(n, m) __attribute__((format(gnu_printf, n, m)))
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# if defined(_WIN32)
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/* Map __printf__ to __gnu_printf__ because we want standard format strings
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* even when MinGW or GLib include files use __printf__. */
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# define __printf__ __gnu_printf__
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# endif
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# endif
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#else
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#define GCC_FMT_ATTR(n, m)
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#endif
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#ifndef __has_feature
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#define __has_feature(x) 0 /* compatibility with non-clang compilers */
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#endif
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/* Implement C11 _Generic via GCC builtins. Example:
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*
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* QEMU_GENERIC(x, (float, sinf), (long double, sinl), sin) (x)
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*
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* The first argument is the discriminator. The last is the default value.
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* The middle ones are tuples in "(type, expansion)" format.
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*/
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/* First, find out the number of generic cases. */
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#define QEMU_GENERIC(x, ...) \
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QEMU_GENERIC_(typeof(x), __VA_ARGS__, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0)
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/* There will be extra arguments, but they are not used. */
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#define QEMU_GENERIC_(x, a0, a1, a2, a3, a4, a5, a6, a7, a8, a9, count, ...) \
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QEMU_GENERIC##count(x, a0, a1, a2, a3, a4, a5, a6, a7, a8, a9)
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/* Two more helper macros, this time to extract items from a parenthesized
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* list.
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*/
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#define QEMU_FIRST_(a, b) a
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#define QEMU_SECOND_(a, b) b
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/* ... and a final one for the common part of the "recursion". */
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#define QEMU_GENERIC_IF(x, type_then, else_) \
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__builtin_choose_expr(__builtin_types_compatible_p(x, \
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QEMU_FIRST_ type_then), \
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QEMU_SECOND_ type_then, else_)
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/* CPP poor man's "recursion". */
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#define QEMU_GENERIC1(x, a0, ...) (a0)
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#define QEMU_GENERIC2(x, a0, ...) QEMU_GENERIC_IF(x, a0, QEMU_GENERIC1(x, __VA_ARGS__))
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#define QEMU_GENERIC3(x, a0, ...) QEMU_GENERIC_IF(x, a0, QEMU_GENERIC2(x, __VA_ARGS__))
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#define QEMU_GENERIC4(x, a0, ...) QEMU_GENERIC_IF(x, a0, QEMU_GENERIC3(x, __VA_ARGS__))
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#define QEMU_GENERIC5(x, a0, ...) QEMU_GENERIC_IF(x, a0, QEMU_GENERIC4(x, __VA_ARGS__))
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#define QEMU_GENERIC6(x, a0, ...) QEMU_GENERIC_IF(x, a0, QEMU_GENERIC5(x, __VA_ARGS__))
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#define QEMU_GENERIC7(x, a0, ...) QEMU_GENERIC_IF(x, a0, QEMU_GENERIC6(x, __VA_ARGS__))
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#define QEMU_GENERIC8(x, a0, ...) QEMU_GENERIC_IF(x, a0, QEMU_GENERIC7(x, __VA_ARGS__))
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#define QEMU_GENERIC9(x, a0, ...) QEMU_GENERIC_IF(x, a0, QEMU_GENERIC8(x, __VA_ARGS__))
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#define QEMU_GENERIC10(x, a0, ...) QEMU_GENERIC_IF(x, a0, QEMU_GENERIC9(x, __VA_ARGS__))
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#endif /* COMPILER_H */
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