This is the mail archive of the gcc-patches@gcc.gnu.org mailing list for the GCC project.

Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]
Other format: [Raw text]

Re: [PATCH, i386]: Implement atomic_fetch_sub

On 2012-08-03 08:01, Uros Bizjak wrote:
> On Fri, Aug 3, 2012 at 4:40 PM, Richard Henderson <rth@redhat.com> wrote:
>> On 2012-08-03 01:51, Uros Bizjak wrote:
>>> The same reasoning goes for dynamic negation: for neg %eax,%eax value
>>> 0x80000000 stays the same, but we have changed (x)sub to an (x)add in
>>> the code stream.
>>
>> So?  Did you think the xadd will trap?
> 
> No, but can we ignore the fact that we changed xsub -0x80000000, mem
> to xadd -0x080000000, mem?

Yes, since it'll have the same effect on the bits.


r~
Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]