[GHC] #15126: Opportunity to compress common info table representation.

[GHC]

#15126: Opportunity to compress common info table representation.
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        Reporter:  AndreasK          |                Owner:  (none)
            Type:  task              |               Status:  new
        Priority:  normal            |            Milestone:  8.8.1
       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:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):  Phab:D4632
       Wiki Page:                    |
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Comment (by AndreasK):

 I've collected some rudimentary stats by analysing the assembly dump for
 nofib/spectral/Simple.

 Out of 2233 info tables, the most common three make up 370, with the most
 common case making up 240 of them.

 I think that case is the small function return (RET_SMALL) with no
 pointers on the stack:

 {{{
 .align 8
         .quad   0
         .long   30
         .long   0
 block_cD9R_info:
 }}}

 But shrinking this further would give up the common info table layout.
 So hard to judge the complexity and cost of this.

 For now just documenting this.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15126#comment:5>
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