https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66412
--- Comment #2 from Uroš Bizjak <ubizjak at gmail dot com> --- (gdb) bt #0 internal_error (gmsgid=0x1d02fb5 "in %s, at %s:%d") at /home/uros/gcc-svn/trunk/gcc/diagnostic.c:1270 #1 0x00000000017291d7 in fancy_abort (file=0x1863c90 "/home/uros/gcc-svn/trunk/gcc/simplify-rtx.c", line=5750, function=0x1864b40 <simplify_subreg(machine_mode, rtx_def*, machine_mode, unsigned int)::__FUNCTION__> "simplify_subreg") at /home/uros/gcc-svn/trunk/gcc/diagnostic.c:1340 #2 0x0000000000d71e51 in simplify_subreg (outermode=HImode, op=0x2aaaae8eacd8, innermode=SImode, byte=0) at /home/uros/gcc-svn/trunk/gcc/simplify-rtx.c:5749 #3 0x0000000000d72b41 in simplify_gen_subreg (outermode=HImode, op=0x2aaaae8eacd8, innermode=SImode, byte=0) at /home/uros/gcc-svn/trunk/gcc/simplify-rtx.c:5969 #4 0x0000000000d77a93 in simplify_replace_fn_rtx (x=0x2aaaae8ea5b8, old_rtx=0x2aaaae8ea2d0, fn=0x10c06e6 <propagate_for_debug_subst(rtx, const_rtx, void*)>, data=0x7fffffffc490) at /home/uros/gcc-svn/trunk/gcc/simplify-rtx.c:511 #5 0x00000000010c0685 in propagate_for_debug (insn=0x2aaaae7bc480, last=0x2aaaae7bc5c0, dest=0x2aaaae8ea2d0, src=0x2aaaae8eaa38, this_basic_block=0x2aaaae7b3958) at /home/uros/gcc-svn/trunk/gcc/valtrack.c:205 #6 0x00000000015e1a04 in try_combine (i3=0x2aaaae7bc580, i2=0x2aaaae7bc540, i1=0x2aaaae7bc400, i0=0x0, new_direct_jump_p=0x7fffffffcc04, last_combined_insn=0x2aaaae7bc580) at /home/uros/gcc-svn/trunk/gcc/combine.c:4386 (gdb) f 2 #2 0x0000000000d71e51 in simplify_subreg (outermode=HImode, op=0x2aaaae8eacd8, innermode=SImode, byte=0) at /home/uros/gcc-svn/trunk/gcc/simplify-rtx.c:5749 5749 gcc_assert (GET_MODE (op) == innermode (gdb) p op $18 = (rtx) 0x2aaaae8eacd8 (gdb) p debug_rtx (op) (eq:QI (reg:CCZ 17 flags) (const_int 0 [0]))