https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106746
--- Comment #17 from Alexandre Oliva <aoliva at gcc dot gnu.org> --- Created attachment 54272 --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=54272&action=edit patch that fixes the problem for reasons not fully understood It seems that looking up the MEM exprs in DEBUG_INSNs disturbs something in cselib and causes pending MEMs to conflict that, in the non-debug case, don't. There's no need for these lookups in debug insns, the results aren't used, and I thought I'd just queue up this improvement but, to my surprise, it made the problem go away.