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| author | klebinger.andreas@gmx.at <klebinger.andreas@gmx.at> | 2018-08-21 12:10:38 -0400 |
|---|---|---|
| committer | Ben Gamari <ben@smart-cactus.org> | 2018-08-21 18:52:42 -0400 |
| commit | 09c1d5afba655a2427a448a9933bebe7d13b696b (patch) | |
| tree | d23083a9e99afe785f632e89f0186af8b191aee2 /compiler/prelude/PrelInfo.hs | |
| parent | 02518f9d99c2d038384263f9e039efcb09bc96ff (diff) | |
| download | haskell-09c1d5afba655a2427a448a9933bebe7d13b696b.tar.gz | |
Replace most occurences of foldl with foldl'.
This patch adds foldl' to GhcPrelude and changes must occurences
of foldl to foldl'. This leads to better performance especially
for quick builds where GHC does not perform strictness analysis.
It does change strictness behaviour when we use foldl' to turn
a argument list into function applications. But this is only a
drawback if code looks ONLY at the last argument but not at the first.
And as the benchmarks show leads to fewer allocations in practice
at O2.
Compiler performance for Nofib:
O2 Allocations:
-1 s.d. ----- -0.0%
+1 s.d. ----- -0.0%
Average ----- -0.0%
O2 Compile Time:
-1 s.d. ----- -2.8%
+1 s.d. ----- +1.3%
Average ----- -0.8%
O0 Allocations:
-1 s.d. ----- -0.2%
+1 s.d. ----- -0.1%
Average ----- -0.2%
Test Plan: ci
Reviewers: goldfire, bgamari, simonmar, tdammers, monoidal
Reviewed By: bgamari, monoidal
Subscribers: tdammers, rwbarton, thomie, carter
Differential Revision: https://phabricator.haskell.org/D4929
Diffstat (limited to 'compiler/prelude/PrelInfo.hs')
| -rw-r--r-- | compiler/prelude/PrelInfo.hs | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/compiler/prelude/PrelInfo.hs b/compiler/prelude/PrelInfo.hs index 2a5fad6733..a76a78adc9 100644 --- a/compiler/prelude/PrelInfo.hs +++ b/compiler/prelude/PrelInfo.hs @@ -171,8 +171,8 @@ knownKeyNamesOkay all_names | otherwise = Just badNamesStr where - namesEnv = foldl (\m n -> extendNameEnv_Acc (:) singleton m n n) - emptyUFM all_names + namesEnv = foldl' (\m n -> extendNameEnv_Acc (:) singleton m n n) + emptyUFM all_names badNamesEnv = filterNameEnv (\ns -> ns `lengthExceeds` 1) namesEnv badNamesPairs = nonDetUFMToList badNamesEnv -- It's OK to use nonDetUFMToList here because the ordering only affects |