[GHC] #11725: Performance Regression from 7.8.3 to 7.10.3

[GHC]

#11725: Performance Regression from 7.8.3 to 7.10.3
-------------------------------------+-------------------------------------
        Reporter:  dominic           |                Owner:  dominic
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  7.10.3
      Resolution:                    |             Keywords:
Operating System:  Linux             |         Architecture:
 Type of failure:  Runtime           |  Unknown/Multiple
  performance bug                    |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
-------------------------------------+-------------------------------------

Comment (by dominic):

 Good news! After a heroic battle fighting cabal, template-haskell,
 unnecessarily restrictive upper bounds and the ghc build system on OS X
 10.11.3,  in which the aforementioned almost won, I managed to get my test
 program to compile under ghc-8.0.1-rc2.

 Under ghc-7.10.2 (NB not comparable with the above as that was done on a
 different machine) I get

 {{{
 Total   time   12.764s  ( 13.242s elapsed)
 }}}

 Under ghc-8.0.1-rc2 I get

 {{{
 Total   time    2.896s  (  3.290s elapsed)
 }}}

 So better even than 7.83.

 For info I ran my comparison of 7.8.3 against 7.10.3 on

 {{{
 processor       : 0
 vendor_id       : GenuineIntel
 cpu family      : 6
 model           : 63
 model name      : Intel(R) Xeon(R) CPU E5-2673 v3 @ 2.40GHz
 stepping        : 2
 microcode       : 0xffffffff
 cpu MHz         : 2397.169
 cache size      : 30720 KB
 physical id     : 0
 siblings        : 1
 core id         : 0
 cpu cores       : 1
 apicid          : 0
 initial apicid  : 0
 fpu             : yes
 fpu_exception   : yes
 cpuid level     : 13
 wp              : yes
 flags           : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca
 cmov pat pse36 clflush mmx fxsr sse sse2 ss syscall nx lm constant_tsc
 rep_good nopl eagerfpu pni pclmulqdq ss\
 se3 fma cx16 sse4_1 sse4_2 movbe popcnt aes xsave avx f16c rdrand
 hypervisor lahf_lm abm fsgsbase bmi1 avx2 smep bmi2 erms xsaveopt
 bugs            :
 bogomips        : 4794.33
 clflush size    : 64
 cache_alignment : 64
 address sizes   : 42 bits physical, 48 bits virtual
 power management:
 }}}

 and I ran my comparison of 7.10.3 againt 8.0.1-rc2 on

 {{{
 Intel(R) Core(TM) i7-3720QM CPU @ 2.60GHz
 }}}

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11725#comment:6>
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