[Bug tree-optimization/97609] [11 Regression] ICE: tree check: expected tree that contains 'decl common' structure, have 'component_ref' in tree_could_trap_p, at tree-eh.c:2708

[aldyh at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97609

--- Comment #3 from Aldy Hernandez <aldyh at gcc dot gnu.org> ---
And the reason this was working before is two-fold.

First, value_of_expr() in legacy evrp won't look at broken gimple, so the
request for __keep_12(D) in the following statement actually succeeds:

  __to_destroy._M_head._M_next = __keep_12(D);

Well... returns NULL.

Second, after replace_uses_in() succeeds, the gimple folder fixes the crappy IL
by transforming:

  __to_destroy._M_head._M_next = __keep_12(D);

into:

  MEM[(struct _Fwd_list_node_base *)&__to_destroy]._M_next = __keep_12(D);


So basically this worked before because even though
substitute_and_fold_engine::replace_uses_in() created invalid gimple, it
depended on the gimple folder to clean-up the nonsense after the fact.  How
stupid is that? :)