From 7485f5cd8a7af9a85292475d2ac0a584a0fc3a86 Mon Sep 17 00:00:00 2001
From: Simon Jakobi <simon.jakobi@gmail.com>
Date: Mon, 13 Jul 2020 01:18:56 +0200
Subject: [PATCH] Remove custom unsafeShift{L,R} definitions (#281)

With GHC < 8.2, the standard `unsafeShift{L,R}` definitions
aren't inlined properly in larger unfoldings. This results
in benchmark slowdowns on the order of 1 to 6%.
---
 Data/HashMap/Base.hs        |  5 ++---
 Data/HashMap/UnsafeShift.hs | 16 ----------------
 unordered-containers.cabal  |  1 -
 3 files changed, 2 insertions(+), 20 deletions(-)
 delete mode 100644 Data/HashMap/UnsafeShift.hs

diff --git a/Data/HashMap/Base.hs b/Data/HashMap/Base.hs
index 007a71b1..395c5fd9 100644
--- a/Data/HashMap/Base.hs
+++ b/Data/HashMap/Base.hs
@@ -129,7 +129,7 @@ import Data.Semigroup (Semigroup((<>)))
 #endif
 import Control.DeepSeq (NFData(rnf))
 import Control.Monad.ST (ST)
-import Data.Bits ((.&.), (.|.), complement, popCount)
+import Data.Bits ((.&.), (.|.), complement, popCount, unsafeShiftL, unsafeShiftR)
 import Data.Data hiding (Typeable)
 import qualified Data.Foldable as Foldable
 #if MIN_VERSION_base(4,10,0)
@@ -144,7 +144,6 @@ import qualified Data.HashMap.Array as A
 import qualified Data.Hashable as H
 import Data.Hashable (Hashable)
 import Data.HashMap.Unsafe (runST)
-import Data.HashMap.UnsafeShift (unsafeShiftL, unsafeShiftR)
 import Data.HashMap.List (isPermutationBy, unorderedCompare)
 import Data.Typeable (Typeable)
 
@@ -2101,7 +2100,7 @@ bitsPerSubkey :: Int
 bitsPerSubkey = 4
 
 maxChildren :: Int
-maxChildren = fromIntegral $ 1 `unsafeShiftL` bitsPerSubkey
+maxChildren = 1 `unsafeShiftL` bitsPerSubkey
 
 subkeyMask :: Bitmap
 subkeyMask = 1 `unsafeShiftL` bitsPerSubkey - 1
diff --git a/Data/HashMap/UnsafeShift.hs b/Data/HashMap/UnsafeShift.hs
deleted file mode 100644
index 529ba504..00000000
--- a/Data/HashMap/UnsafeShift.hs
+++ /dev/null
@@ -1,16 +0,0 @@
-{-# LANGUAGE MagicHash #-}
-
-module Data.HashMap.UnsafeShift
-    ( unsafeShiftL
-    , unsafeShiftR
-    ) where
-
-import GHC.Exts (Word(W#), Int(I#), uncheckedShiftL#, uncheckedShiftRL#)
-
-unsafeShiftL :: Word -> Int -> Word
-unsafeShiftL (W# x#) (I# i#) = W# (x# `uncheckedShiftL#` i#)
-{-# INLINE unsafeShiftL #-}
-
-unsafeShiftR :: Word -> Int -> Word
-unsafeShiftR (W# x#) (I# i#) = W# (x# `uncheckedShiftRL#` i#)
-{-# INLINE unsafeShiftR #-}
diff --git a/unordered-containers.cabal b/unordered-containers.cabal
index c4646eb4..aec2a713 100644
--- a/unordered-containers.cabal
+++ b/unordered-containers.cabal
@@ -46,7 +46,6 @@ library
     Data.HashMap.Strict.Base
     Data.HashMap.List
     Data.HashMap.Unsafe
-    Data.HashMap.UnsafeShift
     Data.HashSet.Base
 
   build-depends: