This compares the contents of @code{*@var{ptr}} with the contents of
@code{*@var{expected}} and if equal, writes @var{desired} into
@code{*@var{ptr}}. If they are not equal, the current contents of
-@code{*@var{ptr}} is written into @code{*@var{expected}}.
+@code{*@var{ptr}} is written into @code{*@var{expected}}. @var{weak} is true
+for weak compare_exchange, and false for the strong variation. Many targets
+only offer the strong variation and ignore the parameter. When in doubt, use
+the strong variation.
True is returned if @code{*@var{desired}} is written into
@code{*@var{ptr}} and the execution is considered to conform to the
@end deftypefn
-@deftypefn {Built-in Function} bool __atomic_always_lock_free (size_t size)
+@deftypefn {Built-in Function} bool __atomic_always_lock_free (size_t size, void *ptr)
-This built-in function returns true if objects of size bytes will always
-generate lock free atomic instructions for the target architecture.
-Otherwise false is returned.
+This built-in function returns true if objects of @var{size} bytes will always
+generate lock free atomic instructions for the target architecture.
+@var{size} must resolve to a compile time constant and the result also resolves to compile time constant.
-size must resolve to a compile time constant.
+@var{ptr} is an optional pointer to the object which may be used to determine
+alignment. A value of 0 indicates typical alignment should be used. The
+compiler may also ignore this parameter.
@smallexample
-if (_atomic_always_lock_free (sizeof (long long)))
+if (_atomic_always_lock_free (sizeof (long long), 0))
@end smallexample
@end deftypefn
-@deftypefn {Built-in Function} bool __atomic_is_lock_free (size_t size)
+@deftypefn {Built-in Function} bool __atomic_is_lock_free (size_t size, void *ptr)
-This built-in function returns true if objects of size bytes will always
+This built-in function returns true if objects of @var{size} bytes will always
generate lock free atomic instructions for the target architecture. If
it is not known to be lock free a call is made to a runtime routine named
@code{__atomic_is_lock_free}.
+@var{ptr} is an optional pointer to the object which may be used to determine
+alignment. A value of 0 indicates typical alignment should be used. The
+compiler may also ignore this parameter.
@end deftypefn
@node Object Size Checking