Is this a bug in ocaml? Or have I mis-configured gas?

Thanks.

../boot/ocamlrun ../ocamlopt -warn-error A -nostdlib `./Compflags
pervasives.cmx                                      ` -c pervasives.ml
/tmp/camlasm9a4b6a.s: Assembler messages:
/tmp/camlasm9a4b6a.s:432: Warning: value 0x3cb0000000000000 truncated to 0x0
/tmp/camlasm9a4b6a.s:438: Warning: value 0x10000000000000 truncated to 0x0
/tmp/camlasm9a4b6a.s:444: Warning: value 0x7fefffffffffffff truncated
to 0xfffff                                      fff
/tmp/camlasm9a4b6a.s:450: Warning: value 0x7ff0000000000001 truncated to 0x1
/tmp/camlasm9a4b6a.s:456: Warning: value 0xfff0000000000000 truncated to 0x0
/tmp/camlasm9a4b6a.s:462: Warning: value 0x7ff0000000000000 truncated to 0x0

../boot/ocamlrun ../ocamlopt -warn-error A -nostdlib `./Compflags
int64.cmx` -c                                       int64.ml
/tmp/camlasm568d6a.s: Assembler messages:
/tmp/camlasm568d6a.s:48: Warning: value 0x7fffffffffffffff truncated
to 0xffffff                                      ff
/tmp/camlasm568d6a.s:54: Warning: value 0x8000000000000000 truncated to 0x0