#14206: Add bit deposit and bit extraction primops -------------------------------------+------------------------------------- Reporter: newhoggy | Owner: (none) Type: feature request | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.2.1 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Description changed by newhoggy: Old description:
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:
New description: 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 for 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#comment:3 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler