[LLVMdev] Where does llvm.memcpy.i64 and friends get lowered ?

Chris Lattner clattner at apple.com
Sun Jul 19 12:54:57 PDT 2009

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  

> 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.

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