https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68400
--- Comment #4 from Steve Ellcey <sje at gcc dot gnu.org> --- Created attachment 37469 --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=37469&action=edit New patch Here is an alternative patch. The problem is that memory_operand matches any legal MIPS memory reference and does not take the MIPS16 limitations (such as illegal base registers) into account. I will submit this new patch after running it through the GCC testsuite.