[Bug tree-optimization/91178] [9/10 Regression] Infinite recursion in split_constant_offset in slp after r260289

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91178

--- Comment #10 from Richard Biener <rguenth at gcc dot gnu.org> ---
Yeah, in the end it's still the vectorizers awkward [dead] code generation but
for this testcase (for me) it recurses too deeply via the VN triggered by
complete unrolling, doing vn_reference_maybe_forwprop_address recursively
on the IL.  Fortunately this specific case is easily dealt with (compile-time
may still be an issue here I guess).