#4928: Add primops for copying/cloning an array
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Reporter: tibbe | Owner:
Type: feature request | Status: new
Priority: normal | Component: Runtime System
Version: 7.0.1 | Keywords:
Testcase: | Blockedby:
Os: Unknown/Multiple | Blocking:
Architecture: Unknown/Multiple | Failure: None/Unknown
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Daniel Peebles's benchmarks show that copying arrays using a
`indexArray#`/`writeArray#` loop is much slower than using a (new) primop
that calls `memcpy`. In addition, cloning arrays is slower than it need to
be due to `newArray#` filling the array with a default element, just to
have all the elements be overwritten by the contents of the array being
cloned.
I suggest we add the following primops:
{{{
copyArray# :: Array# a -> Int# -> MutableArray# s a -> Int#
-> Int# -> State# s -> State# s
copyMutableArray# :: MutableArray# a -> Int# -> MutableArray# s a -> Int#
-> Int# -> State# s -> State# s
cloneArray# :: Array# a -> Int# -> Int# -> State# s -> (#
State# s, Array# a #)
cloneMutableArray# :: MutableArray# s a -> Int# -> Int# -> State# s -> (#
State# s, MutableArray# s a #)
freezeArray# :: MutableArray# s a -> Int# -> Int# -> State# s -> (# State#
s, Array# a #)
thawArray# :: Array# a -> Int# -> Int# -> State# s -> (# State#
s, MutableArray# s a #)
}}}
Note that `ByteArray#` versions can be created using FFI calls to `memcpy`
and thus don't need to be primops.
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/4928>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler
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