llvm dev - Jul 2009 - [LLVMdev] Where does llvm.memcpy.i64 and friends get lowered ?

On Jul 19, 2009, at 8:35 AM, Aaron Gray wrote:
> I am getting a simular problem with ___main appearing if '@main' is
> used but there is no instance of it in the Module iterators, only in  
> the relocations.
>
> Is it possible to do something about these 'ghost symbols' and have
> them defined in Module. Rather than having to check for them and  
> pick them up when processing relocations.
You should not be walking the module.

-Chris
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2009/7/19 Chris Lattner <clattner at apple.com>
>
>  On Jul 19, 2009, at 8:35 AM, Aaron Gray wrote:
>
>  I am getting a simular problem with ___main appearing if '@main'
is used
> but there is no instance of it in the Module iterators, only in the
> relocations.
>
> Is it possible to do something about these 'ghost symbols' and have
them
> defined in Module. Rather than having to check for them and pick them up
> when processing relocations.
>
>
> You should not be walking the module.
>
How else do you get the right symbol info ?

But as I have said lowering functions donot generate there substitute value
symbols in the Module. They just magically appear in the relocations without
being in the module. This is a design flaw in LLVM.

I have done a hack in the COFF writer's relocation code to get round this
for now. But it does not work very well with symbol indexes.

But am thinking of doing a cleanup pass, or walk the module to get this
info.

What do you mean "You should not be walking the module." ?

Thanks,

Aaron


>
> -Chris
>
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On Jul 19, 2009, at 12:43 PM, Aaron Gray wrote:
> 2009/7/19 Chris Lattner <clattner at apple.com>
>
> On Jul 19, 2009, at 8:35 AM, Aaron Gray wrote:
>
>> I am getting a simular problem with ___main appearing if
'@main' is
>> used but there is no instance of it in the Module iterators, only  
>> in the relocations.
>>
>> Is it possible to do something about these 'ghost symbols' and
have
>> them defined in Module. Rather than having to check for them and  
>> pick them up when processing relocations.
>
> You should not be walking the module.
>
> How else do you get the right symbol info ?
You see symbol definitions and references come through the code  
generator.
> But as I have said lowering functions donot generate there  
> substitute value symbols in the Module. They just magically appear  
> in the relocations without being in the module. This is a design  
> flaw in LLVM.
You do not understand how the code generator works.
> I have done a hack in the COFF writer's relocation code to get round  
> this for now. But it does not work very well with symbol indexes.
>
> But am thinking of doing a cleanup pass, or walk the module to get  
> this info.
>
> What do you mean "You should not be walking the module." ?
You should not walk the function list of the module.  You should not  
use Module* for anything other than handling file scope inline asm and  
walking the global variables.

-Chris
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