[LLVMdev] Correctness of Optimization Phases

[deveshti at comp.nus.edu.sg]

Hi,

I tried this thing (Optimization phase sequence) randomly and found that
original fear that they might not produce the same output is true. :-(

Yes, I think only load of testing is the only way out, if you want to get
out.




On Wed, July 19, 2006 5:57 am, Misha Brukman wrote:
> On Wed, Jul 19, 2006 at 03:09:44AM +0800, deveshti at comp.nus.edu.sg
> wrote:
>> I may sound stupid but can someone tell me that after applying
>> optimization sequences randomly whether we can surely say that the
>> final output is correct?
>
> Answering this question is equivalent to solving the Halting Problem.
>
>> I mean if we apply 12 options in random sequence provided by 'opt'
>> command is the output is always correct  (i.e. program does the same
>> thing and results are same as expected) ?
>>
>> Is it Yes by implemention of LLVM or we have to check everytime?
>
> It is the intended effect that the output is always correct, but LLVM
> has no proof of this happening.  Testing on lots and lots of programs
> and inputs is what is currently done to find whether there are bugs.
>
> --
> Misha Brukman :: http://misha.brukman.net
>