https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79027
--- Comment #8 from John David Anglin <danglin at gcc dot gnu.org> --- The error on the trunk is caused by the middle end trying to do a mode change between SImode and BLKmode. Tweaking pa_cannot_change_mode_class() to reject changes to/modes with zero size appears to fix this bug. Running a full build and check. The bug has been present for a long time but only recently exposed by a gcc-8 change and/or selecting the right configure options.
