llvm dev - Apr 2011 - [LLVMdev] finding integer undefined behaviors using clang

Patch and documentation can be found here:

   http://embed.cs.utah.edu/ubc/

John

On Apr 8, 2011, at 8:27 AM, John Regehr wrote:
> Patch and documentation can be found here:
> 
>   http://embed.cs.utah.edu/ubc/
It seems that this could be merged into -fcatch-undefined-behavior while
separating mechanism from policy:

1) Adding checks for more undefined behavior.

2) Allowing different choices of trap mechanism when undefined behavior is
encountered.

Cameron

On Apr 8, 2011, at 4:07 PM, Cameron Zwarich wrote:
> On Apr 8, 2011, at 8:27 AM, John Regehr wrote:
> 
>> Patch and documentation can be found here:
>> 
>>  http://embed.cs.utah.edu/ubc/
> 
> It seems that this could be merged into -fcatch-undefined-behavior while
separating mechanism from policy:
> 
> 1) Adding checks for more undefined behavior.
> 
> 2) Allowing different choices of trap mechanism when undefined behavior is
encountered.
I forgot to say that this is nice work. A lot of people don't even know
about undefined behavior like this, and it is hard to catch it while you are
programming even if you do know about it.

Cameron

Hi Cameron,

I agree, it would be nice to integrate this.  My quick analysis of the 
situation, however, was that there's probably some difference of opinion 
about how heavyweight the trap handler should be.  Ours is very heavy, in 
order to produce informative messages.  People using traps in production 
code -- for example to simulate infinitely-ranged integers -- aren't going 
to like this.  It's probably possible to engineer a solution that makes 
everyone happy, but it may be quite a bit of work.

In the meantime I wanted to get our code out there so people can use it. 
My hope is that if it turns out to be valuable, someone more conversant 
with LLVM will figure out how it fits into the bigger picture.

John