#2132: Optimise nested comparisons
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Reporter: simonpj | Owner:
Type: bug | Status: patch
Priority: lowest | Milestone: 7.6.1
Component: Compiler | Version: 6.8.2
Resolution: | Keywords:
Os: Unknown/Multiple | Architecture: Unknown/Multiple
Failure: Runtime performance bug | Difficulty: Unknown
Testcase: | Blockedby:
Blocking: | Related:
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Comment(by simonmar):
C/C++ compilers use abstract interpretation to do this, e.g.
[http://en.wikipedia.org/wiki/Sparse_conditional_constant_propagation].
This could be expressed very nicely as a Hoopl optimisation, which would
deal nicely with loops too. However, at the Hoopl level we would only be
able to optimise within a single function or closure, whereas doing this
at the Core level has far greater reach.
I don't have any specific comments about this particular implementation -
there's a lot of code and I haven't fully reviewed it. I still think the
best way forward is for this to be a plugin; I think all the
infrastructure is in place to make this work.
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/2132#comment:26>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler
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