https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71575
--- Comment #8 from Richard Biener <rguenth at gcc dot gnu.org> --- We run into #1 0x000000000175ce2f in translate_isl_ast_to_gimple::copy_cond_phi_nodes ( this=0x7fffffffd9a0, bb=<basic_block 0x7ffff6891410 (6)>, new_bb=<basic_block 0x7ffff69d1138 (33)>, iv_map=...) at /space/rguenther/src/svn/gcc-6-branch/gcc/graphite-isl-ast-to-gimple.c:2498 2498 gcc_unreachable (); (gdb) l 2493 tree res = gimple_phi_result (phi); 2494 if (virtual_operand_p (res)) 2495 continue; 2496 if (is_gimple_reg (res) && scev_analyzable_p (res, region->region)) 2497 /* Cond phi nodes should not be scev_analyzable_p. */ 2498 gcc_unreachable (); 2499 2500 gphi *new_phi = create_phi_node (SSA_NAME_VAR (res), new_bb); 2501 tree new_res = create_new_def_for (res, new_phi, 2502 gimple_phi_result_ptr (new_phi)); the issue went latent on the trunk.