[GHC] #9718: Avoid TidyPgm predicting what CorePrep will do
GHC
ghc-devs at haskell.org
Mon Dec 3 11:50:29 UTC 2018
#9718: Avoid TidyPgm predicting what CorePrep will do
-------------------------------------+-------------------------------------
Reporter: simonpj | Owner: (none)
Type: task | Status: new
Priority: normal | Milestone:
Component: Compiler | Version: 7.8.3
Resolution: | Keywords: CodeGen, CAFs
Operating System: Unknown/Multiple | Architecture:
| Unknown/Multiple
Type of failure: None/Unknown | Test Case:
Blocked By: | Blocking:
Related Tickets: | Differential Rev(s):
Wiki Page: |
-------------------------------------+-------------------------------------
Comment (by simonpj):
In GHC today, the `CafInfo` for top-level bindings is set by
`TidyPgm.tidyTopBind`, which in turn uses `hasCafRefs`.
Note that `hasCafRefs` returns true if
* The binding mentions CAFFy things
* The binding ''is'' a CAF
Notice the the code in `hasCafRefs` has all kind of wierd stuff to do with
integer literals; this vanishes entirely in your new code because the
integer-literal expansion is done by the time your new analysis gets to
it.
But you may need to look at
{{{
is_caf = not (arity > 0 || rhsIsStatic (targetPlatform dflags)
is_dynamic_name
cvt_literal expr)
}}}
The `rhsIsStatic` code (in `CoreUtils`) is basically looking for a thunk.
But it has some kind of special case for DLLs -- you should ensure that
your new analysis deals correctly with this.
`rhsIsStatic` also has code for dealing with partial applications, which I
don't think we need. So I think you only need a MUCH simpler function.
--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9718#comment:22>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler
More information about the ghc-tickets
mailing list