Ugh. I apparently had a misunderstanding about how that was compiled.
-Edward
On Wed, Mar 15, 2017 at 5:14 PM, Ben Gamari <b...@smart-cactus.org> wrote:
> Edward Kmett <ekm...@gmail.com> writes:
>
> > Currently if you try to use a DoubleX4# and don't have AVX2 turned on, it
> > deliberately crashes out during code generation, no?
>
> I very well be missing something, but I don't believe this is true. This
> program compiles just fine with merely -fllvm -msse,
>
> {-# LANGUAGE MagicHash #-}
> {-# LANGUAGE UnboxedTuples #-}
> module Hi where
> import GHC.Prim
> import GHC.Float
>
> addIt :: DoubleX4# -> DoubleX4# -> DoubleX4#
> addIt x y = plusDoubleX4# x y
> {-# NOINLINE addIt #-}
>
> It produces the following assembler,,
>
> movupd 0x10(%rbp),%xmm0
> movupd 0x0(%rbp),%xmm1
> movupd 0x30(%rbp),%xmm2
> movupd 0x20(%rbp),%xmm3
> addpd %xmm1,%xmm3
> addpd %xmm0,%xmm2
> movupd %xmm2,0x30(%rbp)
> movupd %xmm3,0x20(%rbp)
> mov 0x40(%rbp),%rax
> lea 0x20(%rbp),%rbp
> jmpq *%rax
>
> The reason for this is that the LLVM code generator just blindly
> translates DoubleX4# to LLVM's <4 x double> type. The LLVM code
> generator then does whatever it can to produce the code we ask of it,
> even if the target doesn't have support for this vector variety.
>
> Cheers,
>
> - Ben
>
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