Thu Mar 5 07:41:53 PST 2009 Simon Marlow <[email protected]>
* Partial fix for #2917
Ignore-this: 3a06cd3ea09f1d6454d52031802a93fd
- add newAlignedPinnedByteArray# for allocating pinned BAs with
arbitrary alignment
- the old newPinnedByteArray# now aligns to 16 bytes
Foreign.alloca will use newAlignedPinnedByteArray#, and so might end
up wasting less space than before (we used to align to 8 by default).
Foreign.allocaBytes and Foreign.mallocForeignPtrBytes will get 16-byte
aligned memory, which is enough to avoid problems with SSE
instructions on x86, for example.
There was a bug in the old newPinnedByteArray#: it aligned to 8 bytes,
but would have failed if the header was not a multiple of 8
(fortunately it always was, even with profiling). Also we
occasionally wasted some space unnecessarily due to alignment in
allocatePinned().
I haven't done anything about Foreign.malloc/mallocBytes, which will
give you the same alignment guarantees as malloc() (8 bytes on
Linux/x86 here).
M ./Foreign/Marshal/Alloc.hs -2 +16
M ./GHC/ForeignPtr.hs -4 +6
View patch online:
http://darcs.haskell.org/ghc-6.10/packages/base/_darcs/patches/20090305154153-12142-5bb4e5d63218021c9092a802e82bc781fc800198.gz
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