#3234: foldr/single no longer firing in GHC 6.10
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Reporter: r6 | Owner:
Type: bug | Status: new
Priority: normal | Component: Compiler
Version: 6.10.3 | Severity: normal
Keywords: | Testcase:
Os: Unknown/Multiple | Architecture: Unknown/Multiple
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consider the following module
{{{module Foo where x = ['x']++"haskell"}}}
when {{{ghc --make -O2 Foo.hs -ddump-simpl-stats}}} is run using GHC
6.8.2, the output show that the foldr/single rule is fired
{{{
5 RuleFired
1 ++
1 augment/build
1 foldr/single
1 unpack
1 unpack-list
}}}
However, I am told that this does not happen in GHC 6.10.2 nor GHC 6.10.3
where foldr/app is fired instead
{{{
6 RuleFired
1 ++
1 augment/build
1 fold/build
1 foldr/app
1 unpack
1 unpack-list
}}}
Thus it appears that the above module is no longer properly optimized in
GHC 6.10
(thanks to dons and Jedai for helping with this)
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/3234>
GHC <http://www.haskell.org/ghc/>
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