On Fri, Oct 24, 2014 at 7:04 PM, Sasha Levin <sasha.le...@oracle.com> wrote: > On 10/24/2014 09:42 AM, Peter Zijlstra wrote: >> On Fri, Oct 24, 2014 at 09:23:35AM -0400, Sasha Levin wrote: >>> >>> i >> 32 may happen to be "i", but is there anything that prevents the >>> compiler >>> from returning, let's say, 42? >> >> Not really, although gcc seems to opt for the 'sane' option and emit the >> instruction and let the arch figure out how to deal with it. Hence the >> 'fun' difference between x86 and ARM. > > It's interesting how many different views on undefined behaviour there are > between > kernel folks. > > Everything between Ted Ts'o saying that GCC can launch nethack on oversized > shifts, > to DaveM saying he will file a GCC bug if the behaviour isn't sane w.r.t to > memcpy().
One of the benefits of fixing such issues (or not letting them into code in the first place) is just saving numerous hours of top-notch engineers spent on disputes like this. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
