Re: [Qemu-devel] [PATCH 2/3 V3] s390: implement pci instructions

[Peter Maydell]

On 21 January 2015 at 13:41, Markus Armbruster <address@hidden> wrote:
> I suspect we shift signed values all over the place, without regard for
> signed overflow.  Machines are fine with that, but some day some
> compiler wiseguy may find a way to save a femtosecond or two for some
> program that never does that, breaking programs that do it, and then
> we'll be in trouble.

clang with its undefined behaviour sanitizers will warn at runtime
when we do this. I've sent out some patches to fix instances of
this in the past. Coverity will also warn in some cases I think.

> We should follow the kernel's lead and compile with
> -fno-strict-overflow.

I don't believe that option affects signed shifts, only signed
addition, subtraction and multiplication.

-- PMM