[LLVMdev] ARM ATPCS ABI support

[James Molloy]

> Problem is that today Clang compiles FreeBSD code as apcs-gnu
> which is in my understanding wrong.

The -mabi=aapcs option to Clang should correct this.

> -----Original Message-----
> From: llvmdev-bounces at cs.uiuc.edu [mailto:llvmdev-bounces at cs.uiuc.edu]
> On Behalf Of Damjan Marion
> Sent: 24 June 2011 12:02
> To: Alasdair Grant
> Cc: llvmdev at cs.uiuc.edu
> Subject: Re: [LLVMdev] ARM ATPCS ABI support
>
>
> On Jun 24, 2011, at 12:52 PM, Alasdair Grant wrote:
>
> >> 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.
>
> Yes, long term goal is definitely to go to aapcs.
>
> My question is more about bridging the gap until that is done
> and also providing compatibility with older binaries.
>
> Problem is that today Clang compiles FreeBSD code as apcs-gnu
> which is in my understanding wrong.
>
> Also clang fails to compile some C++ code as SizeType is defined
> as UnsignedLong for apcs-gnu (should be UnsignedInt).
>
>
>
>
>
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