On Freitag, 24. Juli 2020 16:32:18 CEST Thomas Huth wrote: > When using --enable-werror for the macOS builders in the Cirrus-CI, > the atomic64 test is currently failing, and config.log shows a bunch > of error messages like this: > > config-temp/qemu-conf.c:6:7: error: implicit declaration of function > '__atomic_load_8' is invalid in C99 > [-Werror,-Wimplicit-function-declaration] y = __atomic_load_8(&x, 0); > ^ > config-temp/qemu-conf.c:6:7: error: this function declaration is not a > prototype [-Werror,-Wstrict-prototypes] > > Seems like these __atomic_*_8 functions are available in one of the > libraries there, so that the test links and passes there when not > using --enable-werror. But there does not seem to be a valid prototype > for them in any of the header files, so that the test fails when using > --enable-werror. > > Fix it by using the "official" built-in functions instead (see e.g. > https://gcc.gnu.org/onlinedocs/gcc/_005f_005fatomic-Builtins.html). > We are not using the *_8 variants in QEMU anyway. > > Suggested-by: Christian Schoenebeck <qemu_...@crudebyte.com> > Signed-off-by: Thomas Huth <th...@redhat.com> > --- > configure | 10 +++++----- > 1 file changed, 5 insertions(+), 5 deletions(-) > > diff --git a/configure b/configure > index 4bd80ed507..9eaf501f50 100755 > --- a/configure > +++ b/configure > @@ -5919,11 +5919,11 @@ int main(void) > { > uint64_t x = 0, y = 0; > #ifdef __ATOMIC_RELAXED > - y = __atomic_load_8(&x, 0); > - __atomic_store_8(&x, y, 0); > - __atomic_compare_exchange_8(&x, &y, x, 0, 0, 0); > - __atomic_exchange_8(&x, y, 0); > - __atomic_fetch_add_8(&x, y, 0); > + y = __atomic_load_n(&x, __ATOMIC_RELAXED); > + __atomic_store_n(&x, y, __ATOMIC_RELAXED); > + __atomic_compare_exchange_n(&x, &y, x, 0, __ATOMIC_RELAXED, > __ATOMIC_RELAXED); + __atomic_exchange_n(&x, y, __ATOMIC_RELAXED);
Ah right, there is also the __atomic_*_n() variant of these functions. I actually had the more generic variants in mind. But LGTM and yes, it resolves the warnings on macOS, so ... Reviewed-by: Christian Schoenebeck <qemu_...@crudebyte.com> > + __atomic_fetch_add(&x, y, __ATOMIC_RELAXED); > #else > typedef char is_host64[sizeof(void *) >= sizeof(uint64_t) ? 1 : -1]; > __sync_lock_test_and_set(&x, y); Best regards, Christian Schoenebeck
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