[LLVMdev] Dependence Analysis [was: Flow-Sensitive AA]

[Vikram S. Adve]

On Aug 22, 2008, at 4:14 PM, Daniel Berlin wrote:

> On Fri, Aug 22, 2008 at 5:03 PM, Vikram S. Adve <vadve at cs.uiuc.edu>  
> wrote:
>> Thanks!  This is all very interesting, and tells me that LLVM has a
>> way to go to fully support all of these capabilities (if that is the
>> right thing to do, which isn't clear).  OTOH, it looks like a lot of
>> real-world software that is using LLVM already doesn't seem to be
>> affected by the lack of them.
>>
>> Does anyone know of any C/C++ programs that require integer overflow
>> on signed arithmetic (even though it is not strictly allowed by the
>> standard)?
>
> Yes, see the unending discussion on the gcc mailing list about
> programs we are breaking that led to the introduction of this option.
>
> My serious suggestion would be to tell any users who require this flag
> to shove it.
> :)

That sounds good to me!  In any case, for dependence analysis and  
parallel code generation at least, we have many more fish to fry  
before this even becomes an issue.

>
>
> (Otherwise you end up in a very dark place because there are a lot of
> optimizations that make assumptions about overflow when rearranging
> expressions, etc).



--Vikram
Associate Professor, Computer Science
University of Illinois at Urbana-Champaign
http://llvm.org/~vadve