See also PR36343 which fixes the issue by not pruning points-to-sets at all.
I have a patch.
Subject: Bug 36346
Date: Thu May 29 10:31:58 2008
New Revision: 136152
2008-05-29 Richard Guenther <email@example.com>
* tree-flow.h (clobber_what_p_points_to): Declare.
* tree-ssa-structalias.c (set_uids_in_ptset): Whether the
pointed-to variable is dereferenced is irrelevant to whether
the pointer can access the pointed-to variable.
(clobber_what_p_points_to): New function.
* tree-ssa-alias.c (set_initial_properties): Use it.
* tree-ssa.c (verify_flow_sensitive_alias_info): Adjust
call clobber check for NMTs.
* gcc.c-torture/execute/pr36343.c: New testcase.