[LLVMdev] LLVM 2.0 and integer signedness

Alberto González a.gonzalezsanchez at student.tudelft.nl
Tue Jun 26 10:57:23 PDT 2007


I'm using LLVM to instrument C code to test the efectiveness of some  
methods of error detection with dynamic invariants (see http:// 
citeseer.ist.psu.edu/hangal02tracking.html). I'm using also a range  
invariant (max an min values seen). The problem is that for those  
invariants, I need to know if the value is signed or not (0xFF can be  
-1 or 255, depending on signed/unsigned).

Alberto

El 26/06/2007, a las 18:22, Chris Lattner escribió:

> On Tue, 26 Jun 2007, [ISO-8859-1] Alberto González wrote:
>> The problem is that what i'm instrumenting is loads and stores, plus
>> function call arguments and return values, which have no signedness
>> information.
>
> Why do you need this?
>
> -Chris
>
>> El 26/06/2007, a las 17:03, Anton Korobeynikov escribió:
>>
>>> Hello, Alberto.
>>>
>>>> I'm using llvm for instrumenting code, and I need to know if
>>>> there's a way to
>>>> difference between signed and unsigned Values of integer type
>>>> during an
>>>> optimization pass.
>>> Types are signless in LLVM 2, operations are not. So, you should
>>> probably inspect insts itself, not their operands.
>>>
>>> --
>>> With best regards, Anton Korobeynikov.
>>>
>>> Faculty of Mathematics & Mechanics, Saint Petersburg State  
>>> University.
>>>
>>>
>>> _______________________________________________
>>> LLVM Developers mailing list
>>> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
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>>
>>
>> _______________________________________________
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>
> -Chris
>
> -- 
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