[LLVMdev] Some question on LLVM design

[Marc Ordinas i Llopis]

Misha Brukman wrote:
> 
>>1. Opcodes and intrinsics
>>
> That's not really correct.  The intrinsics such as llvm.frameaddress and
> llvm.returnaddress have no equivalents in LLVM opcodes -- the meaning of
> the intrinsics is specifically machine-dependent, and LLVM (and its
> opcodes) are machine-independent, so there is no valid interchange of
> these intrinsics with any combination of LLVM opcodes.
> 

Yes, I understand that those intrinsics are mapped differently on 
different machines, but isn't 'add' mapped differently too?

It seems to me that those intrinsics are there to support the GNU C 
extensions, making them a 'language feature' of sorts. That's why they 
are intrinsics and not opcodes.

>>3. Control transfer
>>
> LLVM has the 'call' instruction that abstracts the target machine's
> calling convention.  See http://llvm.cs.uiuc.edu/docs/LangRef.html#i_call
> for more information.
> 

Yes, it abstracts the target's C calling convention. But I'm trying to 
see if other types of languages can be implemented using LLVM.

> What is that you are looking to express that isn't captured by the
> `call' instruction?
> 

Tail calls, closures, continuations, lazy allocation... Basically I'm 
trying to see how am I going to implement high-level functions on LLVM.

> Hope that helps,

Certainly, thanks!

Marc Ordinas i Llopis | Tragnarion Studios