http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53083
--- Comment #11 from Pierre Ossman <ossman at cendio dot se> --- Created attachment 30419 --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=30419&action=edit main.c We've also been hitting this, so here is a reduced test case to provoke the bug. Output in the failing case: test_spans(nspans=36) 101,100 + 1 101,0 + 1 0,100 + 0 Aborted (core dumped) And for a correct run: test_spans(nspans=36) 101,100 + 1 101,100 + 1 101,100 + 1 101,100 + 1 101,101 + 1 101,101 + 1 101,99 + 1 101,99 + 1 101,102 + 1 ...