llvm dev - Mar 2005 - [LLVMdev] Recursive Types using the llvm support library

As far as I can tell, when you construct a type using the support
library StructType::get, you have to pass in a list of types.  How can
you make a Recursive type by passing in a pointer to the type you are
constucting.

An example where something really simple like the line below was output
would be perfect.

%struct.linked_list = type { %struct.linked_list*, %sbyte* }


Thanks for any help,
       John

On Mon, 7 Mar 2005, John Carrino wrote:
> As far as I can tell, when you construct a type using the support
> library StructType::get, you have to pass in a list of types.  How can
> you make a Recursive type by passing in a pointer to the type you are
> constucting.
>
> An example where something really simple like the line below was output
> would be perfect.
>
> %struct.linked_list = type { %struct.linked_list*, %sbyte* }
Use something like this:

   PATypeHolder StructTy = OpaqueType::get();
   std::vector<const Type*> Elts;
   Elts.push_back(PointerType::get(StructTy));
   Elts.push_back(PointerType::get(Type::SByteTy));
   StructType *NewSTy = StructType::get(Elts);

   // At this point, NewSTy = "{ opaque*, sbyte* }", tell VMCore that
   // the struct and the opaque type are actually the same.
   cast<OpaqueType>(StructTy.get())->refineAbstractTypeTo(NewSTy);

   // NewSTy is potentially invalidated, but StructTy (a PATypeHolder) is
   // kept up-to-date.
   NewSTy = StructTy.get();


-Chris

-- 
http://nondot.org/sabre/
http://llvm.cs.uiuc.edu/

On Mon, Mar 07, 2005 at 10:51:30PM -0600, Chris Lattner
wrote:
> On Mon, 7 Mar 2005, John Carrino wrote:
> >As far as I can tell, when you construct a type using the support
> >library StructType::get, you have to pass in a list of types.  How can
> >you make a Recursive type by passing in a pointer to the type you are
> >constucting.
> >
> >An example where something really simple like the line below was output
> >would be perfect.
> >
> >%struct.linked_list = type { %struct.linked_list*, %sbyte* }
> 
> Use something like this:
> 
>   PATypeHolder StructTy = OpaqueType::get();
>   std::vector<const Type*> Elts;
>   Elts.push_back(PointerType::get(StructTy));
>   Elts.push_back(PointerType::get(Type::SByteTy));
>   StructType *NewSTy = StructType::get(Elts);
> 
>   // At this point, NewSTy = "{ opaque*, sbyte* }", tell VMCore
that
>   // the struct and the opaque type are actually the same.
>   cast<OpaqueType>(StructTy.get())->refineAbstractTypeTo(NewSTy);
> 
>   // NewSTy is potentially invalidated, but StructTy (a PATypeHolder) is
>   // kept up-to-date.
>   NewSTy = StructTy.get();
Thanks much, Chris.

>> An example where something really simple like the line below was output
>> would be perfect.
>>
>> %struct.linked_list = type { %struct.linked_list*, %sbyte* }
> 
> Use something like this:
> 
>   PATypeHolder StructTy = OpaqueType::get();
>   std::vector<const Type*> Elts;
>   Elts.push_back(PointerType::get(StructTy));
>   Elts.push_back(PointerType::get(Type::SByteTy));
>   StructType *NewSTy = StructType::get(Elts);
> 
>   // At this point, NewSTy = "{ opaque*, sbyte* }", tell VMCore
that
>   // the struct and the opaque type are actually the same.
>   cast<OpaqueType>(StructTy.get())->refineAbstractTypeTo(NewSTy);
> 
>   // NewSTy is potentially invalidated, but StructTy (a PATypeHolder) is
>   // kept up-to-date.
>   NewSTy = StructTy.get();
> 
Is assert(!NewSTy->isAbstract()) must pass  after this line?

Vladimir