[GHC] #15164: Slowdown in ghc compile times from GHC 8.0.2 to GHC 8.2.1 when doing Called arity analysis

[GHC]

#15164: Slowdown in ghc compile times from GHC 8.0.2 to GHC 8.2.1 when doing Called
arity analysis
-------------------------------------+-------------------------------------
        Reporter:  flip101           |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  highest           |            Milestone:  8.6.1
       Component:  Compiler          |              Version:  8.2.1
      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:                    |
-------------------------------------+-------------------------------------
Description changed by nomeata:

Old description:

> Hello,
>
> I have this program that compiles against packages of stack LTS-9.21.
> When i compile with GHC 8.0.2 (version of LTS-9.21) the compiling is
> fast.
>
> 72.01user 34.61system 0:52.98elapsed 201%CPU (0avgtext+0avgdata
> 600684maxresident)k
>
> When i upgrade to LTS-11.9 compiling gets slow. To test if it was a
> problem with new package or GHC (ghc gives some new packages too) i ran:
>
> /usr/bin/time stack build --compiler ghc-8.2.1 --ghc-options="-v3 -j4 -O2
> -fexcess-precision -optc-O3 -optc-ffast-math -rtsopts=none -no-rtsopts-
> suggestions"
>
> with the old package of LTS-9.21 but with the newer GHC 8.2.1 compiler.
> Now the compile times are much higher:
>
> 2481.26user 663.66system 35:38.82elapsed 147%CPU (0avgtext+0avgdata
> 674732maxresident)k
>
> I already took out parts of the grammar to get it even to compile. When i
> have the full grammar i can let my laptop compile 24 hours and it's still
> busy.
>
> I was not sure how to further reduce the code. Maybe when a lot of effort
> i can cut out a few lines here and there. So i uploaded the entire
> project here https://github.com/flip111/parser-calledarityanalysis i
> already took out a lot of code. If anyone has suggestions on how to
> further reduce the code i can try.
>
> Because i had debug info on (-v3 flag) i saw it was stuck for a long time
> at "Called arity analysis"
>
> I prioritize this bug high because i think the slowdown is very
> problematic.

New description:

 Hello,

 I have this program that compiles against packages of stack LTS-9.21. When
 i compile with GHC 8.0.2 (version of LTS-9.21) the compiling is fast.
 {{{
 72.01user 34.61system 0:52.98elapsed 201%CPU (0avgtext+0avgdata
 600684maxresident)k
 }}}
 When i upgrade to LTS-11.9 compiling gets slow. To test if it was a
 problem with new package or GHC (ghc gives some new packages too) i ran:
 {{{
 /usr/bin/time stack build --compiler ghc-8.2.1 --ghc-options="-v3 -j4 -O2
 -fexcess-precision -optc-O3 -optc-ffast-math -rtsopts=none -no-rtsopts-
 suggestions"
 }}}
 with the old package of LTS-9.21 but with the newer GHC 8.2.1 compiler.
 Now the compile times are much higher:
 {{{
 2481.26user 663.66system 35:38.82elapsed 147%CPU (0avgtext+0avgdata
 674732maxresident)k
 }}}
 I already took out parts of the grammar to get it even to compile. When i
 have the full grammar i can let my laptop compile 24 hours and it's still
 busy.

 I was not sure how to further reduce the code. Maybe when a lot of effort
 i can cut out a few lines here and there. So i uploaded the entire project
 here https://github.com/flip111/parser-calledarityanalysis i already took
 out a lot of code. If anyone has suggestions on how to further reduce the
 code i can try.

 Because i had debug info on (-v3 flag) i saw it was stuck for a long time
 at "Called arity analysis"

 I prioritize this bug high because i think the slowdown is very
 problematic.

--

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15164#comment:10>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler