llvm dev - Oct 2011 - [LLVMdev] Request for merge: GHC/ARM calling convention.

Hello,

today is the last day[1] when someone might ask for feature merge into 
the LLVM 3.0 release. I'd like to ask you to merge attached patch. This 
is implementation of GHC calling convention on ARM platform which is 
made by Stephen Blackheath with few additions by me. I hope that 
although the patch does not contain any test case, it still will be 
merged. The reason for this is that the patch itself is short and easy 
to read and it should not affect other parts of LLVM at all (from 
reading the code). Also the patch itself is already tested quite a lot 
by me, since using this I've built various GHC HEAD version over the 
time of last 3 months[2]. Also the patch does not add new feature (GHC 
calling convention) since this is already well supported on x86/x64 
platform, but the patch just enhances this support to also support ARM 
platform and its really just ARM specific hence not affecting any other 
platform.

By including this patch you will easy adoption of GHC on ARM platform, 
and although GHC is already available on ARM platform in its 
"unregisterised" form, when LLVM is available with patch applied, GHC 
might be build in "registerised" form. This provides not only a lot of
nice features of GHC (GHCi, Template Haskell, DPH etc.) but also 
significant performance improvement[3]. This all is missing from 
"unregisterised" built and might be presented in case of
LLVM-supported
"registerised" build of GHC.

If you insist an even minimalistic test-case, then please let me know. I 
do have quite a lot of commitments now, but I'll try to come with 
something till the end of this month. Anyway, I still hope that missing 
test is not merge-stopper especially when GHC/LLVM/ARM is tested with 
its own set of tests...

Thanks for considering this!
Karel


[1]: http://lists.cs.uiuc.edu/pipermail/llvmdev/2011-September/043287.html

[2]: 
http://ghcarm.wordpress.com/2011/08/27/current-status-merged-into-ghc-head/

[3]: http://ghcarm.wordpress.com/tag/nofib/
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Hi Karel,
> today is the last day[1] when someone might ask for feature merge into the
LLVM
> 3.0 release. I'd like to ask you to merge attached patch. This is
implementation
> of GHC calling convention on ARM platform which is made by Stephen
Blackheath
> with few additions by me.
I don't know enough to comment on your patch technically, but it should at
least
be perfectly safe to apply: I don't see how it can impact any code that
doesn't
use the GHC calling convention.
>  const unsigned*
>  ARMBaseRegisterInfo::getCalleeSavedRegs(const MachineFunction *MF) const {
> +  bool ghcCall = false;
> +
> +  if (MF) {
> +    const Function *F = MF->getFunction();
> +    ghcCall = (F ? F->getCallingConv() == CallingConv::GHC : false);
> +  }
This bit looks dubious.  Why do you need to do it?

Ciao, Duncan.