cryptarithm2 +8.16%

[Joachim Breitner]

Hi,

due to #9938 ghcspeed did not measure every commit but somewhere in
these commits, cryptarithm2 regressed by 8%:

$ git log 625dd..8d62f9 --oneline
8d62f92 Update nofib submodule, unbreak cryptarithm2
9521a58 Refine test case for #9938
65e3e0b Test case for #9938
4e1e776 Skip T2276_ghci on Darwin, since stdcall is not supported.
b32c227 Fix system linker on Mac OS X
40561cd Fix `heapSizeSuggesionAuto` typo (#9934)
58ac9c8 LlvmCodeGen cross-compiling fixes (#9895)
0cc0cc8 Support pattern synonyms in GHCi (fixes #9900)
6c86635 Update validate-settings.mk
1fefb59 Update parallel submodule to 3.2.0.6 release
d6e7f5d Add export lists to some modules.
6b9e958 Update hoopl and hpc submodules
c55fefc Avoid redundant-import warning (w/o CPP)
bd01af9 Update hsc2hs submodule for de-tabbing
0899caa Use directory-style database for bootstrapping database
c0ab767 We do emit a warning for stdcall now.
1dcef98 Run T9762 only if dynamic libraries are available
9ae78b0 Copy GHC's config.guess/sub over libffi's versions
add6a30 2nd attempt to fix T9032 test-case
3e3aa92 Fix linker interaction between Template Haskell and HPC (#9762)
cc510b4 Make ghc -e fail on invalid declarations
878910e Make ghc -e not exit on valid import commands (#9905)
7a2c9dd Fixup edd233acc19d269385 (T9032 test)
edd233a Test earlier for self-import (Trac #9032)
c3394e0 Attempt to improve cleaning
679a661 A bit of refactoring to TcErrors
c407b5a Comments only
3e96d89 Add a couple of missing cases to isTcReflCo and isTcReflCo_maybe
a6f0f5a Eliminate so-called "silent superclass parameters"

My guess: Related to this:
      * It had unexpected peformance costs, shown up by Trac #3064 and its
        test case.  In monad-transformer code, when constructing a Monad
        dictionary you had to pass an Applicative dictionary; and to
        construct that you neede a Functor dictionary. Yet these extra
        dictionaries were often never used.  (All this got much worse when
        we added Applicative as a superclass of Monad.) Test T3064
        compiled *far* faster after silent superclasses were eliminated.

Happy new year!
Joachim

-- 
Joachim “nomeata” Breitner
  mail at joachim-breitner.de • http://www.joachim-breitner.de/
  Jabber: nomeata at joachim-breitner.de  • GPG-Key: 0xF0FBF51F
  Debian Developer: nomeata at debian.org

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