[GHC] #13739: Very slow linking of profiled executables

[GHC]

#13739: Very slow linking of profiled executables
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        Reporter:  duog              |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  8.2.1-rc2
      Resolution:                    |             Keywords:
Operating System:  Linux             |         Architecture:  x86_64
 Type of failure:  Compile-time      |  (amd64)
  performance bug                    |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by niteria):

 I wanted to compare `gold` to `collect2`, so I run linking of profiled
 `ghc-stage2` under both with and without `--gc-sections`.
 The results:
 {{{
 no --gc-sections, collect2
 real    0m9.456s
 user    0m8.248s
 sys     0m1.168s
 161M    ghc/stage2/build/tmp/ghc-stage2

 no --gc-sections, gold
 real    0m3.122s
 user    0m2.680s
 sys     0m0.441s
 161M    ghc/stage2/build/tmp/ghc-stage2

 --gc-sections, collect2
 real    2m14.460s
 user    2m13.356s
 sys     0m1.087s
 129M    ghc/stage2/build/tmp/ghc-stage2

 --gc-sections, gold
 real    0m3.118s
 user    0m2.691s
 sys     0m0.411s
 129M    ghc/stage2/build/tmp/ghc-stage2
 }}}

 Looks like `gold` doesn't even break a sweat.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13739#comment:18>
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