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| author | Ben Gamari <bgamari.foss@gmail.com> | 2017-10-25 15:53:40 -0400 |
|---|---|---|
| committer | Ben Gamari <ben@smart-cactus.org> | 2017-10-25 16:44:23 -0400 |
| commit | 2c23fff2e03e77187dc4d01f325f5f43a0e7cad2 (patch) | |
| tree | fc7b5386a0545333860b326d0c818684bcefdcd9 /docs/users_guide/using-optimisation.rst | |
| parent | 821adee12e89dbd0a52fde872b633e4e2e9051dc (diff) | |
| download | haskell-2c23fff2e03e77187dc4d01f325f5f43a0e7cad2.tar.gz | |
user-guide: Clarify default optimization flags
Begins to fix #14214.
[skip ci]
Test Plan: Read it.
Reviewers: austin
Subscribers: rwbarton, thomie
GHC Trac Issues: #14214
Differential Revision: https://phabricator.haskell.org/D4098
Diffstat (limited to 'docs/users_guide/using-optimisation.rst')
| -rw-r--r-- | docs/users_guide/using-optimisation.rst | 13 |
1 files changed, 7 insertions, 6 deletions
diff --git a/docs/users_guide/using-optimisation.rst b/docs/users_guide/using-optimisation.rst index 763c778872..ccf9ac50fb 100644 --- a/docs/users_guide/using-optimisation.rst +++ b/docs/users_guide/using-optimisation.rst @@ -52,7 +52,6 @@ So, for example, ``ghc -c Foo.hs`` .. ghc-flag:: -O0 :shortdesc: Disable optimisations (default) :type: dynamic - :reverse: -O :category: optimization-levels Means "turn off all optimisation", reverting to the same settings as @@ -584,7 +583,7 @@ by saying ``-fno-wombat``. :type: dynamic :category: - :default: off + :default: coercion optimisation enabled. Turn off the coercion optimiser. @@ -593,7 +592,7 @@ by saying ``-fno-wombat``. :type: dynamic :category: - :default: off + :default: pre-inlining enabled Turn off pre-inlining. @@ -604,7 +603,7 @@ by saying ``-fno-wombat``. :type: dynamic :category: - :default: off + :default: state hack is enabled Turn off the "state hack" whereby any lambda with a ``State#`` token as argument is considered to be single-entry, hence it is considered @@ -617,7 +616,7 @@ by saying ``-fno-wombat``. :reverse: -fno-omit-interface-pragmas :category: - :default: off + :default: Implied by :ghc-flag:`-O0`, otherwise off. Tells GHC to omit all inessential information from the interface file generated for the module being compiled (say M). This means @@ -634,7 +633,7 @@ by saying ``-fno-wombat``. :reverse: -fno-omit-yields :category: - :default: on + :default: yield points enabled Tells GHC to omit heap checks when no allocation is being performed. While this improves binary sizes by about 5%, it @@ -652,6 +651,8 @@ by saying ``-fno-wombat``. :reverse: -fno-pedantic-bottoms :category: + :default: off + Make GHC be more precise about its treatment of bottom (but see also :ghc-flag:`-fno-state-hack`). In particular, stop GHC eta-expanding through a case expression, which is good for performance, but bad if you are |