John McCall e399e5bd3d Emit calls to objc_unsafeClaimAutoreleasedReturnValue when ...

reclaiming a call result in order to ignore it or assign it
to an __unsafe_unretained variable.  This avoids adding
an unwanted retain/release pair when the return value is
not actually returned autoreleased (e.g. when it is returned
from a nonatomic getter or a typical collection accessor).

This runtime function is only available on the latest Apple
OS releases; the backwards-compatibility story is that you
don't get the optimization unless your deployment target is
recent enough.  Sorry.

rdar://20530049

llvm-svn: 258962

2016-01-27 18:32:30 +00:00

134 KiB

Raw Blame History

View Raw