#7337: GHC does not generate great code for bit-level rotation
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Reporter: bos | Owner:
Type: feature request | Status: new
Priority: normal | Component: Compiler
Version: 7.6.1 | Keywords:
Os: Unknown/Multiple | Architecture: Unknown/Multiple
Failure: None/Unknown | Testcase:
Blockedby: | Blocking:
Related: |
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I'm working on some hashing functions at the moment, and I notice that GHC
generates an {{{or}}} and a pair of shifts for a rotate. The LLVM back end
is smart enough to recover the code's intent via strength reduction and
emit a single {{{rot}}} instruction, but the regular code generator emits
three instructions.
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Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/7337>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler
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