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# On some platforms clang builtin implementations
# require compiler-rt as a runtime library to use.
#
# See:
# - https://bugs.llvm.org/show_bug.cgi?id=28629
m4_define([_CHECK_RUNTIME_testbody], [[
bool f(long long x, long long y, long long* p)
{
return __builtin_mul_overflow(x, y, p);
}
int main() { return 0; }
]])
AC_DEFUN([CHECK_RUNTIME_LIB], [
AC_LANG_PUSH([C++])
AC_MSG_CHECKING([for __builtin_mul_overflow])
AC_LINK_IFELSE(
[AC_LANG_SOURCE([_CHECK_RUNTIME_testbody])],
[
AC_MSG_RESULT([yes])
AC_DEFINE([HAVE_BUILTIN_MUL_OVERFLOW], [1], [Define if you have a working __builtin_mul_overflow])
],
[
ax_check_save_flags="$LDFLAGS"
LDFLAGS="$LDFLAGS --rtlib=compiler-rt -lgcc_s"
AC_LINK_IFELSE(
[AC_LANG_SOURCE([_CHECK_RUNTIME_testbody])],
[
AC_MSG_RESULT([yes, with additional linker flags])
RUNTIME_LDFLAGS="--rtlib=compiler-rt -lgcc_s"
AC_DEFINE([HAVE_BUILTIN_MUL_OVERFLOW], [1], [Define if you have a working __builtin_mul_overflow])
],
[AC_MSG_RESULT([no])])
LDFLAGS="$ax_check_save_flags"
])
AC_LANG_POP
AC_SUBST([RUNTIME_LDFLAGS])
])
|
