[LLVMdev] Strange Multiple Inheritance Errors Using LLVM 2.7

[John Criswell]

Gonsolo wrote:
> Hi.
>
> I had some problems with MI too. See bug 6251.
>   

I'm not sure if our issues are the same.

To clarify, I'm not seeing LLVM miscompile programs that use multiple 
inheritance.  Instead, the LLVM passes that I write and link with LLVM 
are exhibiting strange behavior when they are written using multiple 
inheritance.  It is almost as if GCC itself is miscompiling my code.

Hrm.  Perhaps that is the problem.  I will investigate; I may be using a 
broken version of GCC to compile LLVM.

-- John T.

> g
>
> Am 25.03.2010 um 16:18 schrieb John Criswell <criswell at uiuc.edu>:
>
>   
>> Dear All,
>>
>> I'm currently upgrading SAFECode to the LLVM 2.7 API.  I'm getting  
>> some
>> strange errors in LLVM Passes that use analysis groups and multiple
>> inheritance.
>>
>> To create analysis groups in LLVM 2.6, I would first create a base  
>> class
>> for the analysis group and then another class that inherited from both
>> ModulePass and the analysis group base class.  That worked in LLVM  
>> 2.6,
>> but now in LLVM 2.7 I'm getting strange behavior.  In particular, I'm
>> seeing the wrong functions called when virtual methods of my passes  
>> are
>> called.  For example, when a SAFECode pass would call the getDSGraph()
>> method of the PoolAllocateSimple pass, the releaseMemory() method  
>> would
>> be called instead.
>>
>> Has anyone else seen this really bizarre behavior or know what might  
>> be
>> causing it?  Eliminating multiple inheritance seems to fix the  
>> problem,
>> but it seems to introduce other problems when chaining analysis passes
>> of the same group together.
>>
>> I see this behavior both on Mac OS X and Linux.
>>
>> -- John T.
>>
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