Undefined behaviour in hotspot

Omair Majid omajid at redhat.com
Mon Apr 21 18:30:56 UTC 2014

* David Chase <david.r.chase at oracle.com> [2014-04-21 13:53]:
> On 2014-04-21, at 12:17 PM, Omair Majid <omajid at redhat.com> wrote:
> > I can ping them, but honestly, I wouldn't be surprised at all if the
> > only response I get is "no". I don't have any official communication
> > channels with them, so my input is not any different from anyone else's.
> > 
> > Can you elaborate on what flag/pragma you have in mind? Just something
> > to play nice with NULL pointers?
> Not just null pointers.  Also optimizations that pretend that integer overflow
> doesn't happen (i.e., optimizations that change program behavior when it
> does) also need to be disabled.

My knowledge of C/C++ is fairly limited, so please bear with me. There
are a few relevant options already listed in 'man gcc':

           This option is only active when -fstrict-overflow is active.
           It warns about cases where the compiler optimizes based on
           the assumption that signed overflow does not occur

           This option instructs the compiler to assume that signed
           arithmetic overflow of addition, subtraction and
           multiplication wraps around using twos-complement

Do you mean others?


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