https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97159
--- Comment #1 from Tom de Vries <vries at gcc dot gnu.org> --- Segfaults because tt is NULL: ... Program received signal SIGSEGV, Segmentation fault. 0x00000000012b1a69 in modref_may_conflict (tt=0x0, ref=0x7fffffffd8d0, tbaa_p=true) at /home/vries/oacc/trunk/source-gcc/gcc/tree-ssa-alias.c:2433 2433 if (tt->every_base) (gdb) ... tt comes from summary->loads: ... (gdb) up #1 0x00000000012b1da1 in ref_maybe_used_by_call_p_1 (call=0x7ffff7ff43f0, ref=0x7fffffffd8d0, tbaa_p=true) at /home/vries/oacc/trunk/source-gcc/gcc/tree-ssa-alias.c:2513 2513 if (!modref_may_conflict (summary->loads, ref, tbaa_p)) ... and summary looks like: ... (gdb) p *summary $2 = {loads = 0x0, stores = 0x0, loads_lto = 0x0, stores_lto = 0x0, finished = true} ...