[LLVMdev] casting Constant * to value *?

[Alexander Poddey]

Dear all,

sorry for the delay.
I found the reason for the assertin failure; I made a mistake and thought 
the function pointer for the call instruction would come first, then the 
argument, which is not correct. Therefore the types did not match.
Its working well now.

Thank you all for your suggestions!

Alex



Alexander Poddey wrote:

> John, you are right.
> I 'browsed' the doxygen's inheritance diagram.
> Shouldn't I then be able to cast Constant * to Value*?
> 
> Plugging the retrieved Constant* (from ConstantExpr::getGetElementPtr)
> into Instruction->setOperand compiles, but gives me an assertion failure
> at runtime.
> I have no access to the code at the moment. I will gather more information
> possibly tomorrow.
> 
> Thanks
> Alex
> 
> 
> 
> 
> John Criswell wrote:
> 
>> On 3/17/15 8:40 PM, Alexander Poddey wrote:
>>> Hi all,
>>>
>>> extracting datafields of globals, the API code ends up in a Constant *
>>>
>>>
>>> Constant* const_ptr_103 =
>>> ConstantExpr::getGetElementPtr(gvar_struct_foo, const_ptr_103_indices);
>>>
>>> it can be used to initialize e.g. a new instruction like:
>>>
>>> StoreInst* void_119 = new StoreInst(const_float_102, const_ptr_103,
>>> false, label_entry_113);
>>>
>>>
>>> But how about replacing the operand of an already existing instruction
>>> using a Constant *?
>>>
>>> Instruction->setOperand(1,__needs_a_value*_here__);
>> 
>> If you look at the inheritance tree, you'll see that an llvm::Constant
>> is a subclass of llvm::Value.  Therefore, you can use an llvm::Constant
>> anywhere in which an llvm::Value is needed.
>> 
>> To look at the inheritance tree, look at the LLVM doxygen documentation.
>> 
>> Regards,
>> 
>> John Criswell
>>>
>>>
>>> Thx
>>> Alex
>>>
>>>
>>>
>>>
>>>   
>>>
>>>
>>>
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>> 
>>