isgray           2098 host/minilua.c if(isgray(obj2gco(uv)))
isgray           2223 host/minilua.c if(isgray(o)){
isgray            106 lj_gc.c            if (isgray(obj2gco(uv)))
isgray            312 lj_gc.c          lua_assert(isgray(o));
isgray            790 lj_gc.c          if (isgray(o)) {  /* A closed upvalue is never gray, so fix this. */