#3591: A working program reports <<loop>> when compiled with -O
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Reporter: blamario | Owner: igloo
Type: merge | Status: closed
Priority: normal | Milestone: 6.12.1
Component: Compiler | Version: 6.10.4
Resolution: fixed | Keywords:
Operating System: Linux | Architecture: x86_64 (amd64)
Type of failure: | Test Case: simplCore/should_run/T3591
None/Unknown |
Blocked By: | Blocking:
Related Tickets: |
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Comment (by Simon Peyton Jones ):
In [changeset:"2b74bd9d8b4c6b20f3e8d9ada12e7db645cc3c19/ghc"
2b74bd9d/ghc]:
{{{
#!CommitTicketReference repository="ghc"
revision="2b74bd9d8b4c6b20f3e8d9ada12e7db645cc3c19"
Stop the specialiser generating loopy code
This patch fixes a bad bug in the specialiser, which showed up as
Trac #13429. When specialising an imported DFun, the specialiser could
generate a recusive loop where none existed in the original program.
It's all rather tricky, and I've documented it at some length in
Note [Avoiding loops]
We'd encoutered exactly this before (Trac #3591) but I had failed
to realise that the very same thing could happen for /imported/
DFuns.
I did quite a bit of refactoring.
The compiler seems to get a tiny bit faster on
deriving/perf/T10858
but almost all the gain had occurred before now; this
patch just pushed it over the line.
}}}
--
Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/3591#comment:7
GHC http://www.haskell.org/ghc/
The Glasgow Haskell Compiler
