#3065: Reorder tests in quot to improve code
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Reporter: simonpj | Owner:
Type: bug | Status: new
Priority: normal | Milestone: 6.12 branch
Component: libraries/base | Version: 6.10.1
Resolution: | Keywords:
Difficulty: Unknown | Os: Unknown/Multiple
Testcase: | Architecture: Unknown/Multiple
Failure: Runtime performance bug |
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Comment (by rl):
In general, I agree with you but IMO things are far from equal here. The
test is only there because of one particular quirk of one particular
processor architecture. It isn't needed on the Sparc, for instance. There,
we pay a performance penalty for no reason at all. Even on x86, it isn't
needed for small integer types and I suspect it isn't needed for Int64 on
x86-32. IMO, things like that are best handled by the processor-specific
backend. The code generator should still be able to see the test. The
simplifier isn't doing anything clever with it anyway and I don't see that
changing in the near future (see, for instance #2132).
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/3065#comment:10>
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