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| author | alexbiehl <alex.biehl@gmail.com> | 2017-03-23 20:33:20 +0100 |
|---|---|---|
| committer | alexbiehl <alex.biehl@gmail.com> | 2017-03-23 20:33:20 +0100 |
| commit | 5748f7642e406ddf232fd49edf6366a3e4de8bf0 (patch) | |
| tree | 7c50c4c134812bc27a0214f6a8aca36fc955af9b | |
| parent | e0f1054ba3f27de9dcffdb9b493c88c265cba6d7 (diff) | |
| download | haskell-5748f7642e406ddf232fd49edf6366a3e4de8bf0.tar.gz | |
Try out another hash for FastStrings as discussed in IRC
| -rw-r--r-- | compiler/utils/FastString.hs | 23 |
1 files changed, 12 insertions, 11 deletions
diff --git a/compiler/utils/FastString.hs b/compiler/utils/FastString.hs index 8d1bbb5c67..b09467091d 100644 --- a/compiler/utils/FastString.hs +++ b/compiler/utils/FastString.hs @@ -102,6 +102,7 @@ import FastFunctions import Panic import Util +import Data.Bits ((.&.)) import Control.DeepSeq import Control.Monad import Data.ByteString (ByteString) @@ -129,8 +130,8 @@ import GHC.Conc.Sync (sharedCAF) import GHC.Base ( unpackCString# ) -#define hASH_TBL_SIZE 4091 -#define hASH_TBL_SIZE_UNBOXED 4091# +#define hASH_TBL_SIZE 4096 +#define hASH_TBL_SIZE_UNBOXED 4096# fastStringToByteString :: FastString -> ByteString @@ -453,16 +454,16 @@ cmpStringPrefix ptr1 ptr2 len = do r <- memcmp ptr1 ptr2 len return (r == 0) +hashStr :: Ptr Word8 -> Int -> Int +hashStr (Ptr a#) (I# len#) = loop 0# a# .&. (hASH_TBL_SIZE - 1) + where + !end = plusAddr# a# len# -hashStr :: Ptr Word8 -> Int -> Int - -- use the Addr to produce a hash value between 0 & m (inclusive) -hashStr (Ptr a#) (I# len#) = loop 0# 0# - where - loop h n | isTrue# (n ==# len#) = I# h - | otherwise = loop h2 (n +# 1#) - where !c = ord# (indexCharOffAddr# a# n) - !h2 = (c +# (h *# 128#)) `remInt#` - hASH_TBL_SIZE# + loop h op | isTrue# (eqAddr# op end) = I# h + | otherwise = loop h' (plusAddr# op 1#) + where + !c = ord# (indexCharOffAddr# op 0#) + !h' = h *# 31# +# c -- ----------------------------------------------------------------------------- -- Operations |