[Git][ghc/ghc][wip/ftext-no-length] FastString: Remove cached length field

[Sebastian Graf]

Sebastian Graf pushed to branch wip/ftext-no-length at Glasgow Haskell Compiler / GHC


Commits:
8493e16f by Sebastian Graf at 2020-09-01T15:33:31+02:00
FastString: Remove cached length field

- - - - -


2 changed files:

- compiler/GHC/Data/FastString.hs
- compiler/GHC/Utils/Encoding.hs


Changes:

=====================================
compiler/GHC/Data/FastString.hs
=====================================
@@ -184,7 +184,6 @@ of this string which is used by the compiler internally.
 -}
 data FastString = FastString {
       uniq    :: {-# UNPACK #-} !Int, -- unique id
-      n_chars :: {-# UNPACK #-} !Int, -- number of chars
       fs_sbs  :: {-# UNPACK #-} !ShortByteString,
       fs_zenc :: FastZString
       -- ^ Lazily computed z-encoding of this string.
@@ -499,8 +498,7 @@ mkNewFastStringShortByteString :: ShortByteString -> Int
                                -> IORef Int -> IO FastString
 mkNewFastStringShortByteString sbs uid n_zencs = do
   let zstr = mkZFastString n_zencs sbs
-  chars <- countUTF8Chars sbs
-  return (FastString uid chars sbs zstr)
+  return (FastString uid sbs zstr)
 
 hashStr  :: ShortByteString -> Int
  -- produce a hash value between 0 & m (inclusive)
@@ -525,7 +523,7 @@ hashStr sbs@(SBS.SBS ba#) = loop 0# 0#
 
 -- | Returns the length of the 'FastString' in characters
 lengthFS :: FastString -> Int
-lengthFS fs = n_chars fs
+lengthFS FastString{fs_sbs=sbs} = countUTF8Chars sbs
 
 -- | Returns @True@ if the 'FastString' is empty
 nullFS :: FastString -> Bool


=====================================
compiler/GHC/Utils/Encoding.hs
=====================================
@@ -170,13 +170,13 @@ utf8DecodeShortByteString (SBS ba#)
       let len# = sizeofByteArray# ba# in
       utf8DecodeLazy# (return ()) (utf8DecodeCharByteArray# ba#) len#
 
-countUTF8Chars :: ShortByteString -> IO Int
+countUTF8Chars :: ShortByteString -> Int
 countUTF8Chars (SBS ba) = go 0# 0#
   where
     len# = sizeofByteArray# ba
     go i# n#
       | isTrue# (i# >=# len#) =
-          return (I# n#)
+          (I# n#)
       | otherwise = do
           case utf8DecodeCharByteArray# ba i# of
             (# _, nBytes# #) -> go (i# +# nBytes#) (n# +# 1#)



View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/8493e16ffce91bab1d7b7bb46583d30da6e10599

-- 
View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/8493e16ffce91bab1d7b7bb46583d30da6e10599
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