[LLVMdev] ARM ATPCS ABI support

[Alasdair Grant]

> Both NetBSD and FreeBSD seems to use older ATPCS ABI standard.
> As I can see it is not supported in LLVM.
>
> Seems that ATPCS is predecessor of AAPCS so I wonder how easy is
> to implement it in LLVM/Clang...
>
> Is it worth efforts? Any thoughts?

See http://gcc.gnu.org/ml/gcc/2010-05/msg00468.html :

  "Do they still want their OS to work on modern CPUs with any
   degree of efficiency?  The current ABI diverged from the old for
   good technical reasons, not just for the sake of being different."

If you want it to run efficiently on modern multicore systems you
really need 64-bit alignment of 64-bit types.  ARM dropped support
for the old ABI in the reference tools years ago.

Al

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