[LLVMdev] Using LLVM to compile Objective-C on an Xbox 360

[Alex Rosenberg]

PS3 is not "a Linux derivative." The compilers supplied by SCE for PS3  
game development are highly customized and support a customized ABI  
that will take some time to adjust LLVM and Clang to support.

You'd likely also run afoul of a TRC or two, similar to the problems  
you'll face with Microsoft TCRs mentioned earlier.

Alex

On May 27, 2010, at 12:15 AM, Kevin Wooten wrote:

> Implementing the backend (or editing the current PPC backend as  
> needed) is a definite option.  This seems to be the real question...  
> which is easier... maintaining the PPC backend or maintaining the  
> rewriter.  Currently (in admittedly trivial tests) I have gotten the  
> rewriter to work and output C code.  There are some outstanding  
> issues to do with linking and accessing the reflection information  
> objective-c provides (and the rewriter properly outputs) but I am  
> sure the person/people who wrote the rewriter can answer those  
> fairly simply (or else the rewriter would be fairly useless).
>
> As far as the runtime goes there is an implementation for windows,  
> linux and most likely the PS3 (since it is already a linux  
> derivative using GCC as mentioned).  If we have to create a runtime  
> for PS3 and XBox that seems trivial as the functions are very basic  
> in nature.
>
> My comments on OpenStep were more meant to point to the fact that we  
> would write our own library; really just throwing all notion of  
> OpenStep away.  Instead of NSObject we would create our own base  
> DObject or something along with a DString, DAarry, DSet, DMap, etc.   
> Truthfully this would be our plan anyway because we want to follow  
> the lead of OSX and provide these objects "toll free bridged"...  
> meaning we would implement them using a std c++ library object (e.g.  
> std::basic_string or std::vector) as the first member of the object  
> which will allow us to cast a DString to std::string or DArray to  
> std::vector without any manual or automatic marshaling. As mentioned  
> this is how OSX implements its NS classes, by using the equivalent  
> CF version which again allows casting between the objects.
>
> On May 26, 2010, at 6:19 PM, Dale Johannesen wrote:
>
>> llvm can output C code, but that target has bitrotted severely over  
>> the last few months and nobody seems to be interested in fixing  
>> it.  You may need to do some work there.  Alternatively you could  
>> implement the PPC ABI that you need.  There are several examples of  
>> supporting multiple ABIs on the same hardware, x86 being the most  
>> obvious.  A lot of simple stuff will probably Just Work with the  
>> existing PPC ABI, more complicated stuff may not.  (Only 32-bit PPC  
>> is really maintained, though, there are probably lots of problems  
>> with 64-bit.)
>>
>> Objective C in llvm, AFAIK, is only used on the MacOSX targets and  
>> only tested there.   There are sufficient secret handshakes between  
>> the compiler and the ObjC runtime that it is unlikely to Just Work  
>> in an untested environment.  OpenStep has a familial relationship  
>> to MacOSX ObjC runtime, but they aren't the same and are unlikely  
>> to still be binary compatible at this point.  You may need to do  
>> some work there also.
>>
>> Summary, you can probably get this approach to work, but it's not  
>> as easy as you're hoping.
>>
>> On May 26, 2010, at 5:20 PMPDT, kdubb wrote:
>>
>>> We are looking at using Objective-C/C++ in a new game engine.   
>>> Objective C's duality of being both very dynamic and very "C"  
>>> gives us exactly what we need to make the SDK and engineering of  
>>> games simpler.
>>>
>>> This means that we will need a way to compile it on all platforms  
>>> our games will target.  Currently the major platforms we are  
>>> concerned with include... PC, Mac, XBox 360, PS3, iPhone.  Now the  
>>> PC, Mac, iPhone and PS3 are fairly simple.  If we build our own  
>>> OpenStep libraries we can simply use LLVM to compile directly to  
>>> these platforms; the PS3 although proprietary uses GCC as a C/C++  
>>> compiler so I am assuming Objective-C can be used fairly simply.   
>>> This leaves us with the XBox 360.
>>>
>>> The 360 is a special chip (PowerPC based) with, as far as I have  
>>> researched, a special ABI (Windows derivative).  I haven't the  
>>> faintest clue of whether code from the LLVM PPC backend would even  
>>> work on the 360, much less interoperate with the system libraries.  
>>> So my formulated solution has become this: use an LLVM backend to  
>>> output C code and then compile that code with using MS's XBox 360  
>>> compiler. I believe I have read that LLVM has a C backend already  
>>> but I don't know how to select it.
>>>
>>> If I can get a proof of concept showing Objective-C code running  
>>> on the 360 we are off to the races.  Any help is appreciated just  
>>> not sure if all the pieces/parts exist and/or what I am missing.   
>>> So... is this feasible?  If so... how do I get LLVM to output C  
>>> code?
>>>
>>> Thanks,
>>> Kevin
>>> _______________________________________________
>>> LLVM Developers mailing list
>>> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
>>> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
>>
>
> _______________________________________________
> LLVM Developers mailing list
> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev