llvm calling convention matters

[Johan Tibell]

OK. But that doesn't create a problem for the code we output with the LLVM
backend, no? Or do we support compiling some code with -fllvm and some not
in the same executable?


On Wed, Sep 11, 2013 at 6:56 PM, Geoffrey Mainland <mainland at apeiron.net>wrote:

> We definitely have interop between the native codegen and the LLVM back
> end now. Otherwise anyone who wanted to use the LLVM back end would have
> to build GHC themselves. Interop means that users can install the
> Haskell Platform and still use -fllvm when it makes a performance
> difference.
>
> Geoff
>
> On 09/11/2013 07:59 PM, Johan Tibell wrote:
> > Do nothing different than you're doing for 7.8, we can sort it out
> > later. Just put a comment on the primops saying they're LLVM-only. See
> > e.g.
> >
> >
> >
> https://github.com/ghc/ghc/blob/master/compiler/prelude/primops.txt.pp#L181
> >
> > for an example how to add docs to primops.
> >
> > I don't think we need interop between the native and the LLVM
> > backends. We don't have that now do we (i.e. they use different
> > calling conventions).
> >
> >
> >
> > On Wed, Sep 11, 2013 at 4:51 PM, Geoffrey Mainland
> > <mainland at apeiron.net <mailto:mainland at apeiron.net>> wrote:
> >
> >     On 09/11/2013 07:44 PM, Johan Tibell wrote:
> >     > On Wed, Sep 11, 2013 at 4:40 PM, Geoffrey Mainland
> >     <mainland at apeiron.net <mailto:mainland at apeiron.net>> wrote:
> >     > > Do you mean we need a reasonable emulation of the SIMD primops
> for
> >     > > the native codegen?
> >     >
> >     > Yes. Reasonable in the sense that it computes the right result.
> >     I can
> >     > see that some code might still want to #ifdef (if the fallback
> isn't
> >     > fast enough).
> >
> >     Two implications of this requirement:
> >
> >     1) There will not be SIMD in 7.8. I just don't have the time. In
> fact,
> >     what SIMD support is there already will have to be removed if we
> >     cannot
> >     live with LLVM-only SIMD primops.
> >
> >     2) If we also require interop between the LLVM back-end and the
> native
> >     codegen, then we cannot pass any SIMD vectors in registers---they all
> >     must be passed on the stack.
> >
> >     My plan, as discussed with Simon PJ, is to not support SIMD primops
> at
> >     all with the native codegen. If there is a strong feeling that
> >     this *is
> >     not* the way to go, the I need to know ASAP.
> >
> >     Geoff
> >
> >
> >
>
>
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