[cfe-dev] Objective-C Code Generation

Chris Lattner clattner at apple.com
Sun Feb 24 20:43:22 PST 2008


> Generating code for an Objective-C method involves
> two steps:
>
> 1) Emitting the function that implements the method.
> 2) Set up the class structure to point to it (modify the structure
> directly with the GNU runtime, via functions on the √Čtoil√© and Apple
> runtimes).

Ok.

> The second step is best done via some custom LLVM IR code for each
> runtime.  The first step ought to be able to reuse the code in
> CodeGenFunction::GenerateCode.  Looking at the ObjCMethodDecl class,
> it seems that this implements most of the methods used by the code
> generator, but since they do not have a common superclass specifying
> these functions the code can not easily be used.  Can anyone suggest a
> good way of factoring this out so it can be used in both places?  I
> notice a few TODO and FIXME comments there, so I am hesitant about
> just copying and pasting code that is going to be changed later.

What specifically do you need to do?  In the next runtime, message  
expressions are all pretty simple: they are llvm Function's with  
internal linkage and names that contain the selector.  I assume you  
would like to factor out the argument lowering code?  Is there  
anything else?

-Chris



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