https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113772
--- Comment #4 from Iain Buclaw <ibuclaw at gdcproject dot org> ---
Looking at gcc/builtins.cc, I have a bad feeling that the only compile-time
values one can get out of this built-in are "true" and "defer to run-time"
---
/* Return a one or zero if it can be determined that object ARG1 of size ARG
is lock free on this architecture. */
static tree
fold_builtin_atomic_is_lock_free (tree arg0, tree arg1)
{
if (!flag_inline_atomics)
return NULL_TREE;
/* If it isn't always lock free, don't generate a result. */
if (fold_builtin_atomic_always_lock_free (arg0, arg1) == boolean_true_node)
return boolean_true_node;
return NULL_TREE;
}
---
The upstream contributor who tested this on x86 likely didn't get this because
it's all lock-free.
