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- To: eigen@xxxxxxxxxxxxxxxxxxx
- Subject: [eigen] platform detection for aligned malloc
- From: "Benoit Jacob" <jacob.benoit.1@xxxxxxxxx>
- Date: Fri, 9 Jan 2009 00:01:41 +0100
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Hi,
I'm reworking the platform detection for aligned malloc.
One recent change is that we now need aligned malloc even if
vectorization is not used. So if we want to use _mm_malloc we need to
use it from another header than emmintrin.h. I heard there's a
mm_malloc.h on some platforms but i'm not too sure.
Another finding i made is that on freebsd too, malloc() is 16 byte aligned.
Please find attached a patch, it's the best i can do but it needs improvements.
*Linux:
--> question: in current SVN we always add manually the prototype of
posix_memalign. with this patch, we do it only if not declared by
<cstdlib> that is if _XOPEN_SOURCE<600. Anyway, is this really good
practice? If XOPEN_SOURCE<600 then maybe we really can't use
posix_memalign, i mean, there's got to be a reason why it's not
declared....
---> need to check especially with GCC 3...
*Mac OSX and FreeBSD:
---> Problem solved, we use malloc()
*Other BSDs:
---> no clue
*Solaris:
----> no clue
MSVC:
----> problem solved, we use _aligned_malloc
ICC:
---> we use _mm_malloc. Question: do we need to #include some header,
like <mm_malloc.h>? When vectorization is not enabled we can't count
on emmintrin.h.
Cygwin:
---> Gael formerly made it use _mm_malloc, so same question as ICC,
which header to include?
Old GCC:
Cheers,
Benoit
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