simd branch ready for review

[Simon Marlow]

On 01/02/13 08:19, Geoffrey Mainland wrote:
> On 02/01/2013 08:03 AM, Simon Marlow wrote:
>> On 31/01/13 20:30, Geoffrey Mainland wrote:
>>> 2) SSE support is processor and platform dependent. What is the proper
>>> way for the programmer to know what SSE primitives are available? A CPP
>>> define? If so, what should it be called?
>>>
>>> Right now one can look at the TARGET_* and __GLASGOW_HASKELL_LLVM__ CPP
>>> macros and make a decision as to whether or not SSE primitives are
>>> available, but that's not a great solution. Also, what happens when we
>>> want to add AVX support? How do we control the inclusion of AVX support
>>> when building GHC, and how do we let the programmer know that the AVX
>>> primops/primtypes are available for use?
>>
>> We #define __SSE__: http://hackage.haskell.org/trac/ghc/ticket/7554
>>
>> Similar things would need to happen for AVX.
>
> If I invoke ghc with -msse on a Win32 box then __SSE__ will be 1, but
> that doesn't mean I will be able to use SSE primops due to the stack
> alignment issue on that platform.

I guess we should not allow -msse with -fllvm on Win32.  Or perhaps not 
-msse at all.

> Also, the decision as to whether or not SSE primops will be available at
> all needs to be made when GHC is itself built. How should we expose that
> knob?

Why does it need to be decided at build time?  Isn't it dependent on 
-msse on x86-32, and always available on x86-64?

> As an aside, what's the proper way for me to test the ARM
> cross-compilation support? I'm afraid my patches may break things there.

You could follow the instructions for building an RPi cross-compiler here:

http://hackage.haskell.org/trac/ghc/wiki/Building/Preparation/RaspberryPi

it should be fairly smooth.

Cheers,
	Simon