#5413: Add population count primop
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Reporter: tibbe | Owner:
Type: feature request | Status: new
Priority: normal | Component: Compiler
Version: 7.2.1 | Keywords:
Testcase: | Blockedby:
Os: Unknown/Multiple | Blocking:
Architecture: Unknown/Multiple | Failure: None/Unknown
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Modern CPUs have a `POPCNT` instruction for efficient population count.
This instruction can be used to implement various data structures.
I propose we add the following set of primops
{{{
popCnt8# :: Word# -> Word#
popCnt16# :: Word# -> Word#
popCnt32# :: Word# -> Word#
popCnt64# :: Word64# -> Word#
popCnt# :: Word# -> Word#
}}}
(We use `Word#` for all functions except the 64 bit version as there are
no `Word8`, `Word16#` and `Word32#` types).
Each primop compiles into either a single `POPCNT` instruction or a call
to some fallback function, implemented in C.
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/5413>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler
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