I never used LLVM so I'm looking at the manual right now. It's explained here:

http://llvm.org/docs/CommandGuide/llc.html#cmdoption-mcpu

It autodetects the cpu and optimizes for it.

As I understand, in order to produce generic code you should pass -mcpu=i686 or -mcpu=x86_64. They can be passed to the ghc via -optlc, e.g. -optlc="-mcpu=x86_64".

I'm going to look more carefully to see what is the best option to pass.

On Sun, Apr 27, 2014 at 10:32 PM, Magnus Therning <magnus@therning.org> wrote:

On Sun, Apr 27, 2014 at 10:16:30PM +0200, Nicola Squartini wrote:
> Is it possible that LLVM automatically optimizes for your
> architecture or triggers the use of some simd that is not present on
> my AMDs?

I suppose that might be the case. It is possible to pass options to
specific parts of the compilation process, but I have never looked at
any of this before so help would be very appreciated.

/M

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