foldr/single no longer firing in GHC 6.10
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)
Trac metadata
Trac field | Value |
---|---|
Version | 6.10.3 |
Type | Bug |
TypeOfFailure | OtherFailure |
Priority | normal |
Resolution | Unresolved |
Component | Compiler |
Test case | |
Differential revisions | |
BlockedBy | |
Related | |
Blocking | |
CC | |
Operating system | |
Architecture |