[Bug c++/82985] GCC 7.2.1 crashes when compiling DSO (Direct Sparse Odometry) on Linux Ubuntu 17.10

[trippels at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82985

--- Comment #16 from Markus Trippelsdorf <trippels at gcc dot gnu.org> ---
Created attachment 42606
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=42606&action=edit
somewhat reduced testcase

(Creduce struggles with 7.6MB boost testcases...)

 % g++ -mavx2 -c -O2 FullSystemOptimize.ii -w
FullSystemOptimize.ii: In member function ‘bool
std::FullSystem::doStepFromBackup()’:
FullSystemOptimize.ii:446:6: internal compiler error: in
vn_nary_build_or_lookup_1, at tree-ssa-sccvn.c:1722
 bool FullSystem::doStepFromBackup() {
      ^~~~~~~~~~
0xc52643 vn_nary_build_or_lookup_1
        ../../gcc/gcc/tree-ssa-sccvn.c:1722
0xc546a9 vn_nary_build_or_lookup
        ../../gcc/gcc/tree-ssa-sccvn.c:1758
0xc546a9 vn_reference_lookup_3
        ../../gcc/gcc/tree-ssa-sccvn.c:2037
0xbbe6fe walk_non_aliased_vuses(ao_ref*, tree_node*, void* (*)(ao_ref*,
tree_node*, unsigned int, void*), void* (*)(ao_ref*, tree_node*, void*, bool*),
tree_node* (*)(tree_node*), void*)
        ../../gcc/gcc/tree-ssa-alias.c:2872
0xc53179 vn_reference_lookup(tree_node*, tree_node*, vn_lookup_kind,
vn_reference_s**, bool)
        ../../gcc/gcc/tree-ssa-sccvn.c:2450
0xc558e0 visit_reference_op_load
        ../../gcc/gcc/tree-ssa-sccvn.c:3691
0xc558e0 visit_use
        ../../gcc/gcc/tree-ssa-sccvn.c:4031
0xc57050 process_scc
        ../../gcc/gcc/tree-ssa-sccvn.c:4293
0xc57050 extract_and_process_scc_for_name
        ../../gcc/gcc/tree-ssa-sccvn.c:4349
0xc57050 DFS
        ../../gcc/gcc/tree-ssa-sccvn.c:4401
0xc58496 sccvn_dom_walker::before_dom_children(basic_block_def*)
        ../../gcc/gcc/tree-ssa-sccvn.c:4854
0x10ea63a dom_walker::walk(basic_block_def*)
        ../../gcc/gcc/domwalk.c:265
0xc5905a run_scc_vn(vn_lookup_kind)
        ../../gcc/gcc/tree-ssa-sccvn.c:4978
0xc356df execute
        ../../gcc/gcc/tree-ssa-pre.c:5093