#14206: Add bit deposit and bit extraction primops -------------------------------------+------------------------------------- Reporter: newhoggy | Owner: (none) Type: feature | Status: new request | Priority: normal | Milestone: Component: Compiler | Version: 8.2.1 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- Modern CPUs (on x86, Haswell and newer) have a PDEP instruction for efficient bit deposit and a PEXT instruction for efficient bit extraction. These instructions can be used to implement various data structures. I propose we add the following set of primops {{{#!hs pdep8# :: Word# -> Word# -> Word# pdep16# :: Word# -> Word# -> Word# pdep32# :: Word# -> Word# -> Word# pdep64# :: Word64# -> Word64# -> Word64# pdep# :: Word# -> Word# -> Word# pext8# :: Word# -> Word# -> Word# pext16# :: Word# -> Word# -> Word# pext32# :: Word# -> Word# -> Word# pext64# :: Word64# -> Word64# -> Word64# pext# :: Word# -> Word# -> Word# }}} Each primop compiles into either a single PDEP/PEXT instruction or a call to some fallback function, implemented in C. For reference, see the following library that implements FFI wrapper 32-bit and 64-bit functions for these instructions: https://github.com/haskell-works/hw-prim-bits -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/14206 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler