llvm dev - Apr 2009 - [LLVMdev] Mutating the elements of a ConstantArray

Hello,

I need to append something to the global "llvm.global_ctors".  This
variable may or may not already be declared within the current module.

If I lookup the global variable, I see that it supports a
getOperand(i) and setOperand(i,c), but does not support any way that I
can enlarge that array to add a new record.

Any suggestions?

-- 
Nick Johnson

On Mar 31, 2009, at 4:42 PM, Nick Johnson wrote:
> Hello,
>
> I need to append something to the global "llvm.global_ctors". 
This
> variable may or may not already be declared within the current module.
>
> If I lookup the global variable, I see that it supports a
> getOperand(i) and setOperand(i,c), but does not support any way that I
> can enlarge that array to add a new record.
Hi Nick,

You actually have to create a new ConstantArray with the desired  
elements, then remove the existing llvm.global_ctors constand and  
create a new one to replace it.

Take a look at the GlobalOpt pass for examples of how to do this sort  
of thing.

-Chris

Thanks,

Just one question more:  why does Constant::getVectorElements()
operate on a SmallVector<T>, while ConstantArray::get() operate on a
std::vector<T> ?  What is the distinction between these uses?

Thanks!
Nick


On Tue, Mar 31, 2009 at 7:49 PM, Chris Lattner <clattner at apple.com>
wrote:
>
> On Mar 31, 2009, at 4:42 PM, Nick Johnson wrote:
>
>> Hello,
>>
>> I need to append something to the global "llvm.global_ctors".
This
>> variable may or may not already be declared within the current module.
>>
>> If I lookup the global variable, I see that it supports a
>> getOperand(i) and setOperand(i,c), but does not support any way that I
>> can enlarge that array to add a new record.
>
> Hi Nick,
>
> You actually have to create a new ConstantArray with the desired
> elements, then remove the existing llvm.global_ctors constand and
> create a new one to replace it.
>
> Take a look at the GlobalOpt pass for examples of how to do this sort
> of thing.
>
> -Chris
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>


-- 
Nick Johnson