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Add ifunc check to configure.ac 

configure.ac will now verify if __attribute__((__ifunc__())) can be used in
the build system. If so, HAVE_FUNC_ATTRIBUTE_IFUNC will be defined to 1.
This commit is contained in:
Hans Jansen 2023-06-22 19:46:55 +02:00 committed by Lasse Collin
parent dbb3a536ed
commit 23b5c36fb7
1 changed files with 28 additions and 0 deletions
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28
configure.ac
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@ -859,8 +859,36 @@ AC_COMPILE_IFELSE([
], [
AC_MSG_RESULT([no])
])
CFLAGS="$OLD_CFLAGS"
# __attribute__((__ifunc__())) can be used for one-time initializations,
# similar to __attribute__((__constructor__)).
AC_ARG_ENABLE([ifunc], [AS_HELP_STRING([--disable-ifunc],
[do not use __attribute__((__ifunc__()))])],
[], [enable_ifunc=yes])
if test "x$enable_ifunc" = xyes ; then
OLD_CFLAGS="$CFLAGS"
CFLAGS="$CFLAGS -Werror"
AC_MSG_CHECKING([if __attribute__((__ifunc__())) can be used])
AC_COMPILE_IFELSE([
static void func(void) { return; }
static void (*resolve_func (void)) (void) { return func; }
void func_ifunc (void)
__attribute__ ((__ifunc__ ("resolve_func")));
], [
AC_DEFINE([HAVE_FUNC_ATTRIBUTE_IFUNC], [1],
[Define to 1 if __attribute__((__ifunc__()))
is supported for functions.])
AC_MSG_RESULT([yes])
], [
AC_MSG_RESULT([no])
])
CFLAGS="$OLD_CFLAGS"
fi
###############################################################################
# Checks for library functions.