[GHC] #9370: unfolding info as seen when building a module depends on flags in a previously-compiled module

[GHC]

#9370: unfolding info as seen when building a module depends on flags in a
previously-compiled module
-------------------------------------+-------------------------------------
        Reporter:  carter            |                Owner:  richardfung
            Type:  bug               |               Status:  new
        Priority:  high              |            Milestone:  8.2.1
       Component:  Compiler          |              Version:  7.8.3
      Resolution:                    |             Keywords:  newcomer,
                                     |  Inlining
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  Compile-time      |  Unknown/Multiple
  performance bug                    |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:  #8635             |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by simonpj):

 Matthew is right.

 * Part 1: the easiest thing is to set `Opt_IgnoreInterfacePragmas` to true
 ''only'' if you specify the flag `-fignore-interface-pragmas` explicitly,
 and ''not'' with `-O0`.  Do that in `DynFlags`.  That way an explicit
 `-fignore-interface-pragmas` flag will still work.

 * Part 2: with `O0` we want to switch off all inlining (except
 "compulsory" inlinings; see `InlineCompulsory` in CoreSyn).  I think this
 can conveniently be done by setting `sm_inline = False` in the `SimplMode`
 in `SimplCore`.  Set it in `base_mode`.

 So actually it looks fairly simple.

 Does that help?

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9370#comment:28>
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