[LLVMdev] common type at compile time?

ret val retval386 at gmail.com
Thu Oct 20 10:15:43 PDT 2011

Awesome, that seems to have fixed my Type problem nicely.

Although now I have a mastery "Uses remain when a value is destroyed!"
assert being tripped and I cant seem to find much about it. This code
is still be ran in my runOnModule() method, so everything should still
be fine.

Thanks again

On Thu, Oct 20, 2011 at 12:48 PM, John Criswell <criswell at illinois.edu> wrote:
> On 10/20/11 11:34 AM, ret val wrote:
>> I'm a bit confused. For the Type did you mean something like:
>>         ArrayType *type =
>> ArrayType::get(Type::getInt8PtrTy(M.getContext()), 4);
> I assume that creates an ArrayType of 4 elements whose elements are pointers
> to 8-bit values.  If so, then this is what I meant.
>> This does not work, it gives me ""Wrong type in array element
>> initializer" at runtime.
>> Also it doesn't look like ConstantExpr inherits ConstantArray, so I'm
>> not sure how I could use this instead.
> What I meant here is that each element (Function *, GlobalVariable *) that
> you want to put into the ConstantArray will need to be casted to an i8 *
> type.  To do the casting, you will need to use a bitcast ConstantExpr
> instead of a BitCastInst since you can't use instructions.
> -- John T.
>> Thanks
>> On Thu, Oct 20, 2011 at 12:04 PM, John Criswell<criswell at illinois.edu>
>>  wrote:
>>> On 10/20/11 10:43 AM, ret val wrote:
>>>> I'm trying to create a ConstantArray(whose contents will be of types
>>>> Function*, GlobalVariable *) so I can immediately create a new
>>>> GlobalVariable(that will be in its own section). I'm doing this so I
>>>> have these address stored. In order to create this ConstantArray I
>>>> need a valid ArrayType, but I'm not sure what to use for the element
>>>> type.
>>>> I want this to be done at compile time, so I cant use a BitCastInst to
>>>> make them all generic pointers. What else can I do?
>>> You can use a ConstantExpr (constant expression) for Function  and
>>> GlobalVariable objects.  The ArrayType can be an array of pointers to
>>> 8-byte
>>> characters (basically a void pointer type).
>>> -- John T.
>>>> In other words
>>>> * I built up a vector id like to eventually store as a GlobalVariable
>>>> array: vector<Constant *>    v_elements;
>>>> * Turned it into something for the ConstantArray::get can use:
>>>> ArrayRef<Constant *>    a_elements(v_elements);
>>>> * And now I need to come up with the ArrayType arg for the
>>>> ConstantArray::get() method where I only know: ArrayType::get(???, 4);
>>>> Thanks
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