[GHC] #7067: Add alignment-restricted ForeignPtr allocation actions

[GHC]

#7067: Add alignment-restricted ForeignPtr allocation actions
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 Reporter:  nicolast          |          Owner:                  
     Type:  feature request   |         Status:  new             
 Priority:  normal            |      Component:  libraries/base  
  Version:                    |       Keywords:                  
       Os:  Unknown/Multiple  |   Architecture:  Unknown/Multiple
  Failure:  None/Unknown      |       Testcase:                  
Blockedby:                    |       Blocking:                  
  Related:                    |  
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 Whilst GHC.ForeignPtr exports some actions to allocate buffers containing
 an element of some type, or of some specific byte-length efficiently, and
 there's an implementation of newAlignedPinnedByteArray# used internally,
 there's no way to request such buffer of a given size and at a given
 alignment.

 The ability to enforce a specific alignment for some memory buffer is
 important e.g. when working with SIMD instructions (which is my original
 use-case). My attempts to work-around the lack of this function failed
 miserably (with a reproducible test-case) as mentioned in [1].

 [1] http://www.haskell.org/pipermail/glasgow-haskell-
 users/2012-July/022579.html

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/7067>
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