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Herbert Valerio Riedel authored
This implements the new primops clz#, clz32#, clz64#, ctz#, ctz32#, ctz64# which provide efficient implementations of the popular count-leading-zero and count-trailing-zero respectively (see testcase for a pure Haskell reference implementation). On x86, NCG as well as LLVM generates code based on the BSF/BSR instructions (which need extra logic to make the 0-case well-defined). Test Plan: validate and succesful tests on i686 and amd64 Reviewers: rwbarton, simonmar, ezyang, austin Subscribers: simonmar, relrod, ezyang, carter Differential Revision: https://phabricator.haskell.org/D144 GHC Trac Issues: #9340
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