1f001dc7bc
Weakrefs only tell you if the symbol was defined elsewhere, so you need a further check at runtime to pick the default definition when needed. This could be automated by the compiler, but it does not do it. Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
70 lines
2.3 KiB
C
70 lines
2.3 KiB
C
/* public domain */
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#ifndef COMPILER_H
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#define COMPILER_H
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#include "config-host.h"
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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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#if QEMU_GNUC_PREREQ(3, 4)
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#define QEMU_WARN_UNUSED_RESULT __attribute__((warn_unused_result))
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#else
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#define QEMU_WARN_UNUSED_RESULT
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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 cat(x,y) x ## y
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#define cat2(x,y) cat(x,y)
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#define QEMU_BUILD_BUG_ON(x) \
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typedef char cat2(qemu_build_bug_on__,__LINE__)[(x)?-1:1];
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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_ATTR __attribute__((__unused__, format(printf, 1, 2)))
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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_ATTR __attribute__((__unused__, format(gnu_printf, 1, 2)))
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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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# if defined(__APPLE__)
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# define QEMU_WEAK_ALIAS(newname, oldname) \
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static typeof(oldname) weak_##newname __attribute__((unused, weakref(#oldname)))
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# define QEMU_WEAK_REF(newname, oldname) (weak_##newname ? weak_##newname : oldname)
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# else
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# define QEMU_WEAK_ALIAS(newname, oldname) \
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typeof(oldname) newname __attribute__((weak, alias (#oldname)))
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# define QEMU_WEAK_REF(newname, oldname) newname
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# endif
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#else
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#define GCC_ATTR /**/
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#define GCC_FMT_ATTR(n, m)
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#define QEMU_WEAK_ALIAS(newname, oldname) \
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_Pragma("weak " #newname "=" #oldname)
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#endif
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#endif /* COMPILER_H */
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