[LLVMdev] Is it an opt bug ?

[Seb]

Already done here : http://llvm.org/bugs/show_bug.cgi?id=12130

Thanks for your answers
Best Regards
Seb

2012/2/29 Duncan Sands <baldrick at free.fr>

> Hi Seb,
>
>
>  If I remove datalayout definition, code is not optimized and work as
>> expected.
>> So my question is:
>>
>> What attribute/value/interpretation of data-layout would cause this type
>> of bug?
>>
>
> all kinds of optimizers use datalayout (and are disabled if there is
> none).  For
> example, alias analysis, anything that needs to understand getelementptr
> offsets, the list is endless.
>
> I suggest you open a bug report, describing your original problem as in
> your
> first email.
>
> Ciao, Duncan.
>
>  Thanks for your answers
>> Seb
>>
>> 2012/2/28 Duncan Sands <baldrick at free.fr <mailto:baldrick at free.fr>>
>>
>>
>>    On 28/02/12 17:48, John Regehr wrote:
>>     >> void t2(double *x)
>>     >> {
>>     >>       long long a[2];
>>     >>       a[0] = 3;
>>     >>       a[1] = 5;
>>     >>       *x = * ((double *) a);
>>     >>       *(x+1) = * ((double *) &a[a[0]-2]);
>>     >> }
>>     >
>>     > Doesn't this code violate the strict aliasing rules?
>>
>>    Maybe, but the LLVM IR he showed seems perfectly well defined.
>>
>>    Ciao, Duncan.
>>    ______________________________**_________________
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>>
>>
>>
>
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