[LLVMdev] llvm::Type as llvm::Value in metadata

[Eli Friedman]

On Mon, Mar 26, 2012 at 11:48 PM, Marcus Frenkel
<marcus.frenkel at fernuni-hagen.de> wrote:
> On Tue, Mar 27, 2012 at 01:55 AM, Eli Friedman <eli.friedman at gmail.com>
> wrote:
>>
>> On Mon, Mar 26, 2012 at 3:08 PM, Marcus Frenkel
>> <marcus.frenkel at fernuni-hagen.de> wrote:
>>>
>>> Hi all,
>>>
>>> I've a question about something that's bothering me for quite some time
>>> now: why is a llvm::Function seen as a llvm::Value (in a sense that
>>> llvm::Function is a subclass of llvm::Value), but llvm::Type is not? Should
>>> they not - technically seen - be equal?
>>
>>
>> llvm::Function is a subclass of llvm::Value because you can use a
>> llvm::Function as a value (of type pointer-to-function).  The same is
>> not true for llvm::Type.
>
>
> Yeah, I know that (in fact, I hoped to express exactly that ;) ). The
> question is, why is that so?

Types are purely a compile-time concept in LLVM IR, just like in C;
there isn't any meta-type or reflection data associated with an LLVM
type.

> And how can you store references to llvm::Types
> in the metadata section of a module?

Essentially, you don't; you can store generic data in a string, though.

-Eli