[GHC] #14677: Code generator does not correctly tag a pointer

[GHC]

#14677: Code generator does not correctly tag a pointer
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        Reporter:  simonpj           |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  8.2.2
      Resolution:                    |             Keywords:  CodeGen
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:  15155             |             Blocking:  14626
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by simonpj):

 If you didn't have that `{-# NOINLINE a #-}`, then the `IND_STATIC` would
 point directly to `a1_closure`, and would be correctly tagged.  And in
 general, absent `{-# NOINLINE #-}` directives, I believe that all that
 cases your patch optimises would be optimised by the simplifier to get the
 code you want.

 So that seems to narrow the scope of the optimisation considerably:

 * You save code-size on many (or perhaps all?) `IND_STATIC` closures.
 * You save entering any such `IND_STATIC`s that are marked `NOINLINE`.

 So yes, it's an improvement, but I wonder whether it's worth the extra
 code and maintenance burden?  I'm thinking of someone looking at this code
 in 5 yrs time.

 Do you think it is?

 Thanks for doing this -- I'm not criticising, just trying to understand
 with precision what is and is not happening.  Clarity is good!

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14677#comment:33>
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