Re: undefined behavior of signed left shifts (was Re: [PULL 00/40] ppc patch queue 2015-06-03)

2015-06-05 Thread Peter Maydell
On 5 June 2015 at 16:55, Paolo Bonzini pbonz...@redhat.com wrote: The GCC manual says GCC does not use the latitude given in C99 and C11 only to treat certain aspects of signed '' as undefined, but this is subject to change. It would certainly be nice if they removed the this is subject to

undefined behavior of signed left shifts (was Re: [PULL 00/40] ppc patch queue 2015-06-03)

2015-06-05 Thread Paolo Bonzini
On 05/06/2015 17:45, Peter Maydell wrote: ...but things like (1U 31) are entirely valid. They're only valid until someone does a ~ on them. I think it's reasonable to forbid them in our coding standards, if we want to fix ubsan's warning of (1 31). I don't think it's reasonable for

Re: undefined behavior of signed left shifts (was Re: [PULL 00/40] ppc patch queue 2015-06-03)

2015-06-05 Thread Joseph Myers
On Fri, 5 Jun 2015, Paolo Bonzini wrote: The GCC manual says GCC does not use the latitude given in C99 and C11 only to treat certain aspects of signed '' as undefined, but this is subject to change. It would certainly be nice if they removed the this is subject to change part. The correct