#3027: Specialisation rules fail because dictionary projections do not match
----------------------------------------------+-----------------------------
Reporter: malcolm.wall...@cs.york.ac.uk | Owner:
Type: bug | Status: closed
Priority: normal | Milestone:
Component: Compiler | Version: 6.8.2
Severity: normal | Resolution: fixed
Keywords: | Difficulty: Unknown
Testcase: | Os: Unknown/Multiple
Architecture: Unknown/Multiple |
----------------------------------------------+-----------------------------
Comment (by malcolm.wall...@cs.york.ac.uk):
Yes, the code in the attached archive "specialisation-bug.tar.gz" is for
the originally stated bug, which has been fixed in 6.10.1. To reproduce
it, first compile everything with ghc Viewer.hs --make -O2, then
recompile just the module containing the usage site (Viewer.hs), with -O2
-ddump-simpl or -dverbose-core2core, to see the lack of specialisation (in
ghc-6.8.2) or the presence of the desired specialisation (in ghc-6.10.1).
However, you asked for more information, because the code produced by
6.10.1 is often significantly slower, despite the better job of
specialisation. I have not yet gathered all the pieces you would require
to reproduce this performance regression, which is likely to be a separate
bug/issue altogether.
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/3027#comment:8>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler
_______________________________________________
Glasgow-haskell-bugs mailing list
Glasgow-haskell-bugs@haskell.org
http://www.haskell.org/mailman/listinfo/glasgow-haskell-bugs
