[Git][ghc/ghc][wip/three-way-merge-sort] WIP

[Jade (@Jade)]

Jade pushed to branch wip/three-way-merge-sort at Glasgow Haskell Compiler / GHC


Commits:
1ac6d7a2 by Jade at 2024-04-28T10:37:27+02:00
WIP

- - - - -


1 changed file:

- libraries/ghc-internal/src/GHC/Internal/Data/OldList.hs


Changes:

=====================================
libraries/ghc-internal/src/GHC/Internal/Data/OldList.hs
=====================================
@@ -1645,8 +1645,14 @@ Further improved using a four-way merge, with an additional performance increase
 https://gitlab.haskell.org/ghc/ghc/issues/24280
 -}
 
-sort = sortBy compare
-sortBy cmp ns
+{-# INLINEABLE sort #-} -- allows specialization for the ord instance
+sort = actualSort (>)
+
+{-# INLINEABLE sortBy #-}
+sortBy cmp = actualSort (\x y -> cmp x y == GT)
+
+actualSort :: (a -> a -> Bool) -> [a] -> [a]
+actualSort gt ns
   | []        <- ns = []
   | [a]       <- ns = [a]
   | [a,b]     <- ns = merge [a] [b]
@@ -1654,8 +1660,6 @@ sortBy cmp ns
   | [a,b,c,d] <- ns = merge4 [a] [b] [c] [d]
   | otherwise       = merge_all (sequences ns)
   where
-    x `gt` y = x `cmp` y == GT
-
     sequences (a:b:xs)
       | a `gt` b  = descending b [a]  xs
       | otherwise = ascending  b (a:) xs



View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/1ac6d7a2c60118e25373cd78413ec887c212d2a7

-- 
View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/1ac6d7a2c60118e25373cd78413ec887c212d2a7
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