Hi all, I was wondering if anyone has investigated the alignment of doubles in ghc. On x86 machines, doubles can be aligned on 4 byte boundaries, but there is a performace improvement if they have 8 byte alignment. As far as I can tell, ghc uses 4 byte alignment for doubles. I started to look into the changes needed to go from 4 to 8 byte alignment...
From what I saw, it looks like I need to add -malign-double to the gcc flags in ghc/compiler/main/DriverFlags.hs for the x86 architecture.
The only other place I saw is in the autoconf stuff. The
FPTOOLS_CHECK_ALIGNMENT macro is defined in aclocal.m4, and I can just
set CFLAGS="-malign-double" in that macro (despite the name, that flag
also effects other types...).
Are there any other places that need attention?
Has anyone else looked into this?
Thanks.
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Matthew Donadio