[LLVMdev] [RFC] Proposal to make LLVM-IR endian agnostic

[Samuel Crow]

>________________________________
>From: "Villmow, Micah" <Micah.Villmow at amd.com>
>To: "llvmdev at cs.uiuc.edu" <llvmdev at cs.uiuc.edu>
>Sent: Monday, October 3, 2011 1:36 PM
>Subject: [LLVMdev] [RFC] Proposal to make LLVM-IR endian agnostic
>
>
>One of the projects I am working on with others is to make LLVM-IR endian agnostic. 
> 
>So, I am sending out this proposal for feedback to the LLVM community. I’ve attached
>pretty version of the proposal in PDF format and pasted a 80-column safe text version
>below. 
> 
>I’m looking forward to comments and feedback.
> 
>Thanks,
>Micah Villmow
> 
> 
--snip--

Hello Micah,

Without having read a lot into your plan I'd like to make a few suggestions:  Some game systems use mixed-endian datalayouts as a form of lockouts for homebrew software.  While I believe it isn't a terribly effective mechanism, it does leave LLVM unable to be used for such game systems.  I think LLVM should allow some sort of swizzle mechanism to allow such mixed-endian datalayouts.  (I think swizzle is the correct term.)

Also, as a co-developer of Clang's AROS backend, it would be really handy to have an endian-agnostic bitcode format since our OS covers about 5 different CPU architectures, some of which are big-endian.  We were hoping to base a superset of the ELF loader that would be endian-agnostic based on PNaCl's bitcode format.

Thanks for taking this challenge on,

--Samuel Crow