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| author | klebinger.andreas@gmx.at <klebinger.andreas@gmx.at> | 2018-06-02 21:18:19 -0400 |
|---|---|---|
| committer | Ben Gamari <ben@smart-cactus.org> | 2018-06-02 23:21:00 -0400 |
| commit | 18cb4f5e1b88aef7770446a354bfcc1e0a075e89 (patch) | |
| tree | 67784d663a44400b418d35f5ac5a38f8f39acef9 /compiler/utils | |
| parent | ac91d07399207f4e22467bea3577cafd27a937d7 (diff) | |
| download | haskell-18cb4f5e1b88aef7770446a354bfcc1e0a075e89.tar.gz | |
Check for singletons when creating Bag/OrdList from a list.
This gives us `One x` instead of `Many (x : [])` reducing overhead.
For compiling spectral/simple with -O0 difference was ~ -0.05%
allocations.
The only drawback is that something like toOL (x:panic "") will now
panic. But that seems like a reasonable tradeoff.
Test Plan: ci, looking at +RTS -s
Reviewers: bgamari, jmct
Reviewed By: bgamari
Subscribers: jmct, rwbarton, thomie, carter
Differential Revision: https://phabricator.haskell.org/D4770
Diffstat (limited to 'compiler/utils')
| -rw-r--r-- | compiler/utils/Bag.hs | 1 | ||||
| -rw-r--r-- | compiler/utils/OrdList.hs | 1 |
2 files changed, 2 insertions, 0 deletions
diff --git a/compiler/utils/Bag.hs b/compiler/utils/Bag.hs index 727d1c5f3d..41c80390cc 100644 --- a/compiler/utils/Bag.hs +++ b/compiler/utils/Bag.hs @@ -328,6 +328,7 @@ mapAccumBagLM f s (ListBag xs) = do { (s', xs') <- mapAccumLM f s xs listToBag :: [a] -> Bag a listToBag [] = EmptyBag +listToBag [x] = UnitBag x listToBag vs = ListBag vs bagToList :: Bag a -> [a] diff --git a/compiler/utils/OrdList.hs b/compiler/utils/OrdList.hs index 081210a534..a5739764d4 100644 --- a/compiler/utils/OrdList.hs +++ b/compiler/utils/OrdList.hs @@ -122,4 +122,5 @@ foldlOL k z (Many xs) = foldl k z xs toOL :: [a] -> OrdList a toOL [] = None +toOL [x] = One x toOL xs = Many xs |