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| author | Joachim Breitner <mail@joachim-breitner.de> | 2017-08-26 14:35:50 +0200 |
|---|---|---|
| committer | Joachim Breitner <mail@joachim-breitner.de> | 2017-10-29 00:00:57 -0400 |
| commit | 0e953da147c405648356f75ee67eda044fffad49 (patch) | |
| tree | 7d4b5b02603048e0f68b2541423fcbc4d2aa7866 /docs | |
| parent | 97ca0d249c380a961a4cb90afb44bfcee1f632f2 (diff) | |
| download | haskell-0e953da147c405648356f75ee67eda044fffad49.tar.gz | |
Implement a dedicated exitfication pass #14152
The idea is described in #14152, and can be summarized: Float the exit
path out of a joinrec, so that the simplifier can do more with it.
See the test case for a nice example.
The floating goes against what the simplifier usually does, hence we
need to be careful not inline them back.
The position of exitification in the pipeline was chosen after a small
amount of experimentation, but may need to be improved. For example,
exitification can allow rewrite rules to fire, but for that it would
have to happen before the `simpl_phases`.
Perf.haskell.org reports these nice performance wins:
Nofib allocations
fannkuch-redux 78446640 - 99.92% 64560
k-nucleotide 109466384 - 91.32% 9502040
simple 72424696 - 5.96% 68109560
Nofib instruction counts
fannkuch-redux 1744331636 - 3.86% 1676999519
k-nucleotide 2318221965 - 6.30% 2172067260
scs 1978470869 - 3.35% 1912263779
simple 669858104 - 3.38% 647206739
spectral-norm 186423292 - 5.37% 176411536
Differential Revision: https://phabricator.haskell.org/D3903
Diffstat (limited to 'docs')
| -rw-r--r-- | docs/users_guide/using-optimisation.rst | 10 |
1 files changed, 10 insertions, 0 deletions
diff --git a/docs/users_guide/using-optimisation.rst b/docs/users_guide/using-optimisation.rst index ccf9ac50fb..4714de7788 100644 --- a/docs/users_guide/using-optimisation.rst +++ b/docs/users_guide/using-optimisation.rst @@ -181,6 +181,16 @@ by saying ``-fno-wombat``. Enable call-arity analysis. +.. ghc-flag:: -fexitification + :shortdesc: Enables exitification optimisation. Implied by :ghc-flag:`-O`. + :type: dynamic + :reverse: -fno-exitification + :category: + + :default: on + + Enables the floating of exit paths out of recursive functions. + .. ghc-flag:: -fcmm-elim-common-blocks :shortdesc: Enable Cmm common block elimination. Implied by :ghc-flag:`-O`. :type: dynamic |