[mpich-discuss] Possible integer overflows at scale in gather.c

[Ignacio Laguna]

Rob,

I applied the patch and the analysis doesn't report any scale-dependent 
overflow now. Thanks! This fixes it.

If you are interested, I could try the analysis on other parts of mpich 
that perhaps are not frequently used -- I only tested these functions: 
broadcast, scatter, gather, reduce, alltoall, gatherv, isend, irecv, and 
wait. I didn't try I/O functions for example. We could coordinate this 
in this forum or in a separate email. Just let me know. Unfortunately, 
until we release it, it can only be tested on my side.

Thanks for your help!

Ignacio


On 10/2/15 11:50 AM, Rob Latham wrote:
>
>
> On 10/01/2015 12:35 PM, Ignacio Laguna wrote:
>
>> Once you have a version I can download with the patches, I can run the
>> analysis again and see if I can catch more things. Just let me know and
>> I would be happy to test it.
>
> I tried to decipher the LLVM output: I see a few more i64 values, but
> not certain I'm reading it correctly.
>
> Does this patch do the trick?
>
> Promoting the declaration of recvcount would work too, but sets off a
> larger cascade of  type promotions.
>
> ==rob
>
>>
>> In general, overflows can also occur in intermediate computations,
>> depending on how code is optimized, I believe.
>>
>> Thanks!
>>
>> Ignacio
>>
>>> ==rob
>>>
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