#9532: Expose new CLZ/CTZ primops via `Data.Bits` interface -------------------------------------+------------------------------------- Reporter: hvr | Owner: hvr Type: task | Status: new Priority: normal | Milestone: 7.10.1 Component: | Version: libraries/base | Keywords: Data.Bits Resolution: | Architecture: Unknown/Multiple Operating System: | Difficulty: Unknown Unknown/Multiple | Blocked By: Type of failure: | Related Tickets: #9340 None/Unknown | Test Case: | Blocking: | Differential Revisions: Phab:D158 | -------------------------------------+------------------------------------- Comment (by Herbert Valerio Riedel ): In [changeset:"a8a969ae7a05e408b29961d0a2ea621a16d73d3e/ghc"]: {{{ #!CommitTicketReference repository="ghc" revision="a8a969ae7a05e408b29961d0a2ea621a16d73d3e" Add `FiniteBits(count{Leading,Trailing}Zeros)` This exposes the newly added CLZ/CTZ primops from e0c1767d0ea8d12e0a4badf43682a08784e379c6 (re #9340) via two new methods `countLeadingZeros` and `countTrailingZeros` in the `Data.Bits.FiniteBits` class. The original proposal can be found at http://www.haskell.org/pipermail/libraries/2014-August/023567.html Test Plan: successful validate Reviewers: ekmett, tibbe GHC Trac Issues: #9532 Differential Revision: https://phabricator.haskell.org/D158 }}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/9532#comment:2 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler

#9532: Expose new CLZ/CTZ primops via `Data.Bits` interface -------------------------------------+------------------------------------- Reporter: hvr | Owner: hvr Type: task | Status: closed Priority: normal | Milestone: 7.10.1 Component: | Version: libraries/base | Keywords: Data.Bits Resolution: fixed | Architecture: Unknown/Multiple Operating System: | Difficulty: Unknown Unknown/Multiple | Blocked By: Type of failure: | Related Tickets: #9340 None/Unknown | Test Case: | Blocking: | Differential Revisions: Phab:D158 | -------------------------------------+------------------------------------- Comment (by Herbert Valerio Riedel ): In [changeset:"3241ac56d371220ed0b9522a86678678532f48bc/ghc"]: {{{ #!CommitTicketReference repository="ghc" revision="3241ac56d371220ed0b9522a86678678532f48bc" Remove incorrect property in docstring (re #9532) The property countLeadingZeros . negate = const 0 doesn't generally hold and it's not such a useful property to state, as it simply follows from "sign-bit == most-significant-bit" for FiniteBits types which use twos-complement representation for negative values, and even then it breaks down for 0... TLDR, remove thinko from documentation of `countLeadingZeros` }}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/9532#comment:4 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler