[Bug tree-optimization/23384] escaped set should be flow sensitive

[msebor at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=23384

--- Comment #9 from Martin Sebor <msebor at gcc dot gnu.org> ---
As a data point, Clang manages to optimize at least the simple case in bug
81788 as expected.  No other compiler I've tested does (IBM XLC, Intel ICC,
Visual Studio, or Sun/Oracle Studio).