Re: [AMBER-Developers] SSE2 / SSE3 settings no longer used for ifort?

From: Robert Duke <>
Date: Mon, 26 Oct 2009 14:30:33 -0400

I have been sitting to one side, cringing over this mess (at intel - they
are completely out of control). I think we have to seriously consider doing
an "ifort -v" and parsing the result to be able to handle this. I don't
know what the state of mkl is; I have not looked into whether there is a
reasonable way to get that version... (looking at installed directory names
is really vulnerable to errors...).
Regards - Bob
----- Original Message -----
From: "Ben Roberts" <>
To: "AMBER Developers Mailing List" <>
Sent: Monday, October 26, 2009 2:12 PM
Subject: Re: [AMBER-Developers] SSE2 / SSE3 settings no longer used for

> Hi,
>> Ok, i switched it to -axSTPW.
>> For future work:
>>> However, the warning here is that compilers older than 10.0 do not
>>> support
>>> the S option I believe. Additionally not all the sub options are
>>> supported
>>> by all compiler versions. Then to make things more complicated in ifort
>>> 11.0
>>> and 11.1 Intel has set the -axS... options to deprecated and now says
>>> you
>>> need to use the more verbose SSE4.2,SSE4.1 options etc. I assume that
>>> come
>>> ifort v12 they will remove the -axS... options entirely and hence things
>>> will no longer build. Of course SSE4.2 etc does not work with pre 11.0
>>> compilers and thus the -fast option has its appeal except for the fact
>>> that
>>> it introduces additional issues. So maybe for now we should use -axWPS
>>> which
>>> should work with most post 10.0 Intel compilers for the time being -
>>> maybe
>>> including the T option as well. Then we can issue a patch if Intel
>>> breaks
>>> this in 12.0.
>>>> There is also the compiler version wrinkle as you mentioned.
>>>> If someone has specific recommendations on options then make them;
>>>> otherwise, i suggest we make the small -axS -> -axWPS change for
>>>> the ambertools release and then try fast which will give us months
>>>> to test drive it b4 amber11.
>>> The only other thing is to try to detect the compiler version but this
>>> may
>>> get horribly complicated. Asking the user to provide the compiler
>>> version to
>>> configure is probably a recipe for disaster so if we do have specifics
>>> for
>>> specific compiler versions it should probably be selected automatically.
> Intel 11 on the Mac doesn't like -axW, at least. So we're already into
> compiler version Hades.
> I'm trying to tweak my configure script to best suit Intel 11/Snow
> Leopard. But I'm loath to upload my changes, because I fear they won't be
> backwards-compatible. (I already managed to break the configure script
> once that way.) Is it worth trying to detect compiler versions
> automatically, or is that just opening up a can of worms?
> Ben
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Received on Mon Oct 26 2009 - 12:00:03 PDT
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