ticket for adding ARM backend to NCG?

[Karel Gardas]

On 01/ 3/14 01:37 PM, Simon Peyton-Jones wrote:
> | I've been tinkering with ARM NCG idea for quite some time now, but
> | honestly I've been always in doubts if it's the best way for GHC at all.
> | I've thought that the plan was to kind of move out of NCG to LLVM based
> | backends and I've though that although this plan may be kind of stuck
> | now, it's still on the table.
>
> I have not been following the ARM and LLVM threads very closely, but here's my take:
>
> * LLVM is (I hope) very much on the table. LLVM itself is a well-resourced project,
>    and we can expect it to continue to exist.  We should piggy-back on all the
>    hard work that is going into it.
>
> * But using LLVM has some disadvantages.
>    a) it imposes a dependency on LLVM
>    b) it makes compilation slower
>    c) we play some efficiency tricks (notably "tables next to code") that
>       LLVM can't play (yet).  I think.
>
> So GHC currently aims to have a built-in NCG for popular platforms, and to rely on LLVM for more esoteric platforms and also for superior optimisation.

This sounds indeed good.

> Maybe you can articulate your doubts on the ARM NCG?

My main doubt was to invest a lot of time into something which will be 
deprecated in near future (as ARM NCG will take some time to do) 
assuming GHC is switching to LLVM completely and deprecating NCG. Your 
policy stated above clears that.

Thanks!
Karel