[Bug c++/95638] [10/11 Regression] Legit-looking code doesn't work with -O2

[amker at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95638

--- Comment #6 from bin cheng <amker at gcc dot gnu.org> ---
We call graphds_scc twice to break alias dependence, with alias dependence
edges skipped in the second call.  The code (both before and after
r10-7184-ge4e9a59105a81cdd6c1328b0a5ed9fe4cc82840e) tries to rectify post order
information after the second call, however it never gets it right.  Actually I
don't think it can be easily rectified (if possible).

Will test another patch which records/restores post order information for the
second call.