http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59399
--- Comment #1 from Peter Bergner <bergner at gcc dot gnu.org> --- More hopefully useful gdb output: (gdb) pr decl_rtl (reg:DI 123 [ D.2805+-4 ]) (gdb) ptree exp <var_decl 0xfffafe31a20 D.2805 type <integer_type 0xfffafec0690 int sizes-gimplified public SI size <integer_cst 0xfffafe027c0 constant 32> unit size <integer_cst 0xfffafe027e0 constant 4> align 32 symtab 0 alias set -1 canonical type 0xfffafec0690 precision 32 min <integer_cst 0xfffafe02760 -2147483648> max <integer_cst 0xfffafe02780 2147483647> pointer_to_this <pointer_type 0xfffafec16f8>> used ignored SI file bug.ii line 2 col 1 size <integer_cst 0xfffafe027c0 32> unit size <integer_cst 0xfffafe027e0 4> align 32 context <function_decl 0xfffb0068c00 foo> (reg:DI 123 [ D.2805+-4 ])> (gdb) p DECL_MODE (exp) $8 = SImode (gdb) ptree ssa_name <ssa_name 0xfffafea0708 type <integer_type 0xfffafec0690 int sizes-gimplified public SI size <integer_cst 0xfffafe027c0 constant 32> unit size <integer_cst 0xfffafe027e0 constant 4> align 32 symtab 0 alias set -1 canonical type 0xfffafec0690 precision 32 min <integer_cst 0xfffafe02760 -2147483648> max <integer_cst 0xfffafe02780 2147483647> pointer_to_this <pointer_type 0xfffafec16f8>> visited var <var_decl 0xfffafe31a20 D.2805>def_stmt _3 = UBSAN_CHECK_ADD (j_1(D), i_2(D)); version 3>