add a benchmark

bench/Main.hs

@@ -0,0 +1,57 @@
+import Gauge (bgroup,bench,whnf)
+import Gauge.Main (defaultMain)
+import Data.Word (Word64)
+import Data.Primitive (ByteArray)
+import qualified Data.ByteArray.Builder.Small.Unsafe as U
+
+import qualified HexWord64
+
+main :: IO ()
+main = defaultMain
+  [ bgroup "w64"
+    [ bgroup "hex"
+      [ bench "library" (whnf encodeHexWord64s w64s)
+      , bench "loop" (whnf encodeHexWord64sLoop w64s)
+      ]
+    ]
+  ]
+
+w64s :: Word64s
+w64s = Word64s
+  0xde2b8a480cf77113
+  0x48f1668ca2a68b45
+  0xd262fbaa0b2f473c
+  0xbab20547f4919d9f
+  0xb7ec16121704db43
+  0x9c259f5bfa90e1eb
+  0xd451eca11d9873ad
+  0xbd927e8d4c879d02
+
+data Word64s = Word64s
+  !Word64 !Word64 !Word64 !Word64
+  !Word64 !Word64 !Word64 !Word64
+
+encodeHexWord64s :: Word64s -> ByteArray
+{-# noinline encodeHexWord64s #-}
+encodeHexWord64s (Word64s a b c d e f g h) = U.run $
+  U.word64PaddedUpperHex a `U.append`
+  U.word64PaddedUpperHex b `U.append`
+  U.word64PaddedUpperHex c `U.append`
+  U.word64PaddedUpperHex d `U.append`
+  U.word64PaddedUpperHex e `U.append`
+  U.word64PaddedUpperHex f `U.append`
+  U.word64PaddedUpperHex g `U.append`
+  U.word64PaddedUpperHex h
+
+encodeHexWord64sLoop :: Word64s -> ByteArray
+{-# noinline encodeHexWord64sLoop #-}
+encodeHexWord64sLoop (Word64s a b c d e f g h) = U.run $
+  HexWord64.word64PaddedUpperHex a `U.append`
+  HexWord64.word64PaddedUpperHex b `U.append`
+  HexWord64.word64PaddedUpperHex c `U.append`
+  HexWord64.word64PaddedUpperHex d `U.append`
+  HexWord64.word64PaddedUpperHex e `U.append`
+  HexWord64.word64PaddedUpperHex f `U.append`
+  HexWord64.word64PaddedUpperHex g `U.append`
+  HexWord64.word64PaddedUpperHex h
+