Cleanup in parser/Ctype.hs

* GHC now performs constant folding on bit operations like (.|.) so we
use them and we remove the misleading comment

* we use Word8 instead of Int and we remove the useless conversion to
Int32. Hopefully future releases of GHC could transform the big case in
`charType` into a value table indexing instead of a jump table. Word8
would make the table smaller.

* we use INLINABLE pragma instead of INLINE on `is_ctype`: in my test,
the latter *prevents* `is_ctype` to be inlined because `charType` is
inlined into `is_ctype` (to call charType`s worker on the unboxed Char
directly).

1 files changed, 135 insertions, 138 deletions

diff --git a/compiler/parser/Ctype.hs b/compiler/parser/Ctype.hs
index 9c3988e869..57721da94d 100644
--- a/compiler/parser/Ctype.hs
+++ b/compiler/parser/Ctype.hs
@@ -18,14 +18,14 @@ module Ctype
 
 import GhcPrelude
 
-import Data.Int         ( Int32 )
-import Data.Bits        ( Bits((.&.)) )
+import Data.Bits        ( Bits((.&.),(.|.)) )
 import Data.Char        ( ord, chr )
+import Data.Word
 import Panic
 
 -- Bit masks
 
-cIdent, cSymbol, cAny, cSpace, cLower, cUpper, cDigit :: Int
+cIdent, cSymbol, cAny, cSpace, cLower, cUpper, cDigit :: Word8
 cIdent  =  1
 cSymbol =  2
 cAny    =  4
@@ -37,9 +37,9 @@ cDigit  = 64
 -- | The predicates below look costly, but aren't, GHC+GCC do a great job
 -- at the big case below.
 
-{-# INLINE is_ctype #-}
-is_ctype :: Int -> Char -> Bool
-is_ctype mask c = (fromIntegral (charType c) .&. fromIntegral mask) /= (0::Int32)
+{-# INLINABLE is_ctype #-}
+is_ctype :: Word8 -> Char -> Bool
+is_ctype mask c = (charType c .&. mask) /= 0
 
 is_ident, is_symbol, is_any, is_space, is_lower, is_upper, is_digit,
     is_alphanum :: Char -> Bool
@@ -82,137 +82,134 @@ to_lower c
   | c >=  'A' && c <= 'Z' = chr (ord c - (ord 'A' - ord 'a'))
   | otherwise = c
 
--- | We really mean .|. instead of + below, but GHC currently doesn't do
---  any constant folding with bitops. *sigh*
-
-charType :: Char -> Int
+charType :: Char -> Word8
 charType c = case c of
-   '\0'   -> 0                         -- \000
-   '\1'   -> 0                         -- \001
-   '\2'   -> 0                         -- \002
-   '\3'   -> 0                         -- \003
-   '\4'   -> 0                         -- \004
-   '\5'   -> 0                         -- \005
-   '\6'   -> 0                         -- \006
-   '\7'   -> 0                         -- \007
-   '\8'   -> 0                         -- \010
-   '\9'   -> cSpace                    -- \t  (not allowed in strings, so !cAny)
-   '\10'  -> cSpace                    -- \n  (ditto)
-   '\11'  -> cSpace                    -- \v  (ditto)
-   '\12'  -> cSpace                    -- \f  (ditto)
-   '\13'  -> cSpace                    --  ^M (ditto)
-   '\14'  -> 0                         -- \016
-   '\15'  -> 0                         -- \017
-   '\16'  -> 0                         -- \020
-   '\17'  -> 0                         -- \021
-   '\18'  -> 0                         -- \022
-   '\19'  -> 0                         -- \023
-   '\20'  -> 0                         -- \024
-   '\21'  -> 0                         -- \025
-   '\22'  -> 0                         -- \026
-   '\23'  -> 0                         -- \027
-   '\24'  -> 0                         -- \030
-   '\25'  -> 0                         -- \031
-   '\26'  -> 0                         -- \032
-   '\27'  -> 0                         -- \033
-   '\28'  -> 0                         -- \034
-   '\29'  -> 0                         -- \035
-   '\30'  -> 0                         -- \036
-   '\31'  -> 0                         -- \037
-   '\32'  -> cAny + cSpace             --
-   '\33'  -> cAny + cSymbol            -- !
-   '\34'  -> cAny                      -- "
-   '\35'  -> cAny + cSymbol            --  #
-   '\36'  -> cAny + cSymbol            --  $
-   '\37'  -> cAny + cSymbol            -- %
-   '\38'  -> cAny + cSymbol            -- &
-   '\39'  -> cAny + cIdent             -- '
-   '\40'  -> cAny                      -- (
-   '\41'  -> cAny                      -- )
-   '\42'  -> cAny + cSymbol            --  *
-   '\43'  -> cAny + cSymbol            -- +
-   '\44'  -> cAny                      -- ,
-   '\45'  -> cAny + cSymbol            -- -
-   '\46'  -> cAny + cSymbol            -- .
-   '\47'  -> cAny + cSymbol            --  /
-   '\48'  -> cAny + cIdent  + cDigit   -- 0
-   '\49'  -> cAny + cIdent  + cDigit   -- 1
-   '\50'  -> cAny + cIdent  + cDigit   -- 2
-   '\51'  -> cAny + cIdent  + cDigit   -- 3
-   '\52'  -> cAny + cIdent  + cDigit   -- 4
-   '\53'  -> cAny + cIdent  + cDigit   -- 5
-   '\54'  -> cAny + cIdent  + cDigit   -- 6
-   '\55'  -> cAny + cIdent  + cDigit   -- 7
-   '\56'  -> cAny + cIdent  + cDigit   -- 8
-   '\57'  -> cAny + cIdent  + cDigit   -- 9
-   '\58'  -> cAny + cSymbol            -- :
-   '\59'  -> cAny                      -- ;
-   '\60'  -> cAny + cSymbol            -- <
-   '\61'  -> cAny + cSymbol            -- =
-   '\62'  -> cAny + cSymbol            -- >
-   '\63'  -> cAny + cSymbol            -- ?
-   '\64'  -> cAny + cSymbol            -- @
-   '\65'  -> cAny + cIdent  + cUpper   -- A
-   '\66'  -> cAny + cIdent  + cUpper   -- B
-   '\67'  -> cAny + cIdent  + cUpper   -- C
-   '\68'  -> cAny + cIdent  + cUpper   -- D
-   '\69'  -> cAny + cIdent  + cUpper   -- E
-   '\70'  -> cAny + cIdent  + cUpper   -- F
-   '\71'  -> cAny + cIdent  + cUpper   -- G
-   '\72'  -> cAny + cIdent  + cUpper   -- H
-   '\73'  -> cAny + cIdent  + cUpper   -- I
-   '\74'  -> cAny + cIdent  + cUpper   -- J
-   '\75'  -> cAny + cIdent  + cUpper   -- K
-   '\76'  -> cAny + cIdent  + cUpper   -- L
-   '\77'  -> cAny + cIdent  + cUpper   -- M
-   '\78'  -> cAny + cIdent  + cUpper   -- N
-   '\79'  -> cAny + cIdent  + cUpper   -- O
-   '\80'  -> cAny + cIdent  + cUpper   -- P
-   '\81'  -> cAny + cIdent  + cUpper   -- Q
-   '\82'  -> cAny + cIdent  + cUpper   -- R
-   '\83'  -> cAny + cIdent  + cUpper   -- S
-   '\84'  -> cAny + cIdent  + cUpper   -- T
-   '\85'  -> cAny + cIdent  + cUpper   -- U
-   '\86'  -> cAny + cIdent  + cUpper   -- V
-   '\87'  -> cAny + cIdent  + cUpper   -- W
-   '\88'  -> cAny + cIdent  + cUpper   -- X
-   '\89'  -> cAny + cIdent  + cUpper   -- Y
-   '\90'  -> cAny + cIdent  + cUpper   -- Z
-   '\91'  -> cAny                      -- [
-   '\92'  -> cAny + cSymbol            -- backslash
-   '\93'  -> cAny                      -- ]
-   '\94'  -> cAny + cSymbol            --  ^
-   '\95'  -> cAny + cIdent  + cLower   -- _
-   '\96'  -> cAny                      -- `
-   '\97'  -> cAny + cIdent  + cLower   -- a
-   '\98'  -> cAny + cIdent  + cLower   -- b
-   '\99'  -> cAny + cIdent  + cLower   -- c
-   '\100' -> cAny + cIdent  + cLower   -- d
-   '\101' -> cAny + cIdent  + cLower   -- e
-   '\102' -> cAny + cIdent  + cLower   -- f
-   '\103' -> cAny + cIdent  + cLower   -- g
-   '\104' -> cAny + cIdent  + cLower   -- h
-   '\105' -> cAny + cIdent  + cLower   -- i
-   '\106' -> cAny + cIdent  + cLower   -- j
-   '\107' -> cAny + cIdent  + cLower   -- k
-   '\108' -> cAny + cIdent  + cLower   -- l
-   '\109' -> cAny + cIdent  + cLower   -- m
-   '\110' -> cAny + cIdent  + cLower   -- n
-   '\111' -> cAny + cIdent  + cLower   -- o
-   '\112' -> cAny + cIdent  + cLower   -- p
-   '\113' -> cAny + cIdent  + cLower   -- q
-   '\114' -> cAny + cIdent  + cLower   -- r
-   '\115' -> cAny + cIdent  + cLower   -- s
-   '\116' -> cAny + cIdent  + cLower   -- t
-   '\117' -> cAny + cIdent  + cLower   -- u
-   '\118' -> cAny + cIdent  + cLower   -- v
-   '\119' -> cAny + cIdent  + cLower   -- w
-   '\120' -> cAny + cIdent  + cLower   -- x
-   '\121' -> cAny + cIdent  + cLower   -- y
-   '\122' -> cAny + cIdent  + cLower   -- z
-   '\123' -> cAny                      -- {
-   '\124' -> cAny + cSymbol            --  |
-   '\125' -> cAny                      -- }
-   '\126' -> cAny + cSymbol            -- ~
-   '\127' -> 0                         -- \177
+   '\0'   -> 0                             -- \000
+   '\1'   -> 0                             -- \001
+   '\2'   -> 0                             -- \002
+   '\3'   -> 0                             -- \003
+   '\4'   -> 0                             -- \004
+   '\5'   -> 0                             -- \005
+   '\6'   -> 0                             -- \006
+   '\7'   -> 0                             -- \007
+   '\8'   -> 0                             -- \010
+   '\9'   -> cSpace                        -- \t  (not allowed in strings, so !cAny)
+   '\10'  -> cSpace                        -- \n  (ditto)
+   '\11'  -> cSpace                        -- \v  (ditto)
+   '\12'  -> cSpace                        -- \f  (ditto)
+   '\13'  -> cSpace                        --  ^M (ditto)
+   '\14'  -> 0                             -- \016
+   '\15'  -> 0                             -- \017
+   '\16'  -> 0                             -- \020
+   '\17'  -> 0                             -- \021
+   '\18'  -> 0                             -- \022
+   '\19'  -> 0                             -- \023
+   '\20'  -> 0                             -- \024
+   '\21'  -> 0                             -- \025
+   '\22'  -> 0                             -- \026
+   '\23'  -> 0                             -- \027
+   '\24'  -> 0                             -- \030
+   '\25'  -> 0                             -- \031
+   '\26'  -> 0                             -- \032
+   '\27'  -> 0                             -- \033
+   '\28'  -> 0                             -- \034
+   '\29'  -> 0                             -- \035
+   '\30'  -> 0                             -- \036
+   '\31'  -> 0                             -- \037
+   '\32'  -> cAny .|. cSpace               --
+   '\33'  -> cAny .|. cSymbol              -- !
+   '\34'  -> cAny                          -- "
+   '\35'  -> cAny .|. cSymbol              --  #
+   '\36'  -> cAny .|. cSymbol              --  $
+   '\37'  -> cAny .|. cSymbol              -- %
+   '\38'  -> cAny .|. cSymbol              -- &
+   '\39'  -> cAny .|. cIdent               -- '
+   '\40'  -> cAny                          -- (
+   '\41'  -> cAny                          -- )
+   '\42'  -> cAny .|. cSymbol              --  *
+   '\43'  -> cAny .|. cSymbol              -- +
+   '\44'  -> cAny                          -- ,
+   '\45'  -> cAny .|. cSymbol              -- -
+   '\46'  -> cAny .|. cSymbol              -- .
+   '\47'  -> cAny .|. cSymbol              --  /
+   '\48'  -> cAny .|. cIdent  .|. cDigit   -- 0
+   '\49'  -> cAny .|. cIdent  .|. cDigit   -- 1
+   '\50'  -> cAny .|. cIdent  .|. cDigit   -- 2
+   '\51'  -> cAny .|. cIdent  .|. cDigit   -- 3
+   '\52'  -> cAny .|. cIdent  .|. cDigit   -- 4
+   '\53'  -> cAny .|. cIdent  .|. cDigit   -- 5
+   '\54'  -> cAny .|. cIdent  .|. cDigit   -- 6
+   '\55'  -> cAny .|. cIdent  .|. cDigit   -- 7
+   '\56'  -> cAny .|. cIdent  .|. cDigit   -- 8
+   '\57'  -> cAny .|. cIdent  .|. cDigit   -- 9
+   '\58'  -> cAny .|. cSymbol              -- :
+   '\59'  -> cAny                          -- ;
+   '\60'  -> cAny .|. cSymbol              -- <
+   '\61'  -> cAny .|. cSymbol              -- =
+   '\62'  -> cAny .|. cSymbol              -- >
+   '\63'  -> cAny .|. cSymbol              -- ?
+   '\64'  -> cAny .|. cSymbol              -- @
+   '\65'  -> cAny .|. cIdent  .|. cUpper   -- A
+   '\66'  -> cAny .|. cIdent  .|. cUpper   -- B
+   '\67'  -> cAny .|. cIdent  .|. cUpper   -- C
+   '\68'  -> cAny .|. cIdent  .|. cUpper   -- D
+   '\69'  -> cAny .|. cIdent  .|. cUpper   -- E
+   '\70'  -> cAny .|. cIdent  .|. cUpper   -- F
+   '\71'  -> cAny .|. cIdent  .|. cUpper   -- G
+   '\72'  -> cAny .|. cIdent  .|. cUpper   -- H
+   '\73'  -> cAny .|. cIdent  .|. cUpper   -- I
+   '\74'  -> cAny .|. cIdent  .|. cUpper   -- J
+   '\75'  -> cAny .|. cIdent  .|. cUpper   -- K
+   '\76'  -> cAny .|. cIdent  .|. cUpper   -- L
+   '\77'  -> cAny .|. cIdent  .|. cUpper   -- M
+   '\78'  -> cAny .|. cIdent  .|. cUpper   -- N
+   '\79'  -> cAny .|. cIdent  .|. cUpper   -- O
+   '\80'  -> cAny .|. cIdent  .|. cUpper   -- P
+   '\81'  -> cAny .|. cIdent  .|. cUpper   -- Q
+   '\82'  -> cAny .|. cIdent  .|. cUpper   -- R
+   '\83'  -> cAny .|. cIdent  .|. cUpper   -- S
+   '\84'  -> cAny .|. cIdent  .|. cUpper   -- T
+   '\85'  -> cAny .|. cIdent  .|. cUpper   -- U
+   '\86'  -> cAny .|. cIdent  .|. cUpper   -- V
+   '\87'  -> cAny .|. cIdent  .|. cUpper   -- W
+   '\88'  -> cAny .|. cIdent  .|. cUpper   -- X
+   '\89'  -> cAny .|. cIdent  .|. cUpper   -- Y
+   '\90'  -> cAny .|. cIdent  .|. cUpper   -- Z
+   '\91'  -> cAny                          -- [
+   '\92'  -> cAny .|. cSymbol              -- backslash
+   '\93'  -> cAny                          -- ]
+   '\94'  -> cAny .|. cSymbol              --  ^
+   '\95'  -> cAny .|. cIdent  .|. cLower   -- _
+   '\96'  -> cAny                          -- `
+   '\97'  -> cAny .|. cIdent  .|. cLower   -- a
+   '\98'  -> cAny .|. cIdent  .|. cLower   -- b
+   '\99'  -> cAny .|. cIdent  .|. cLower   -- c
+   '\100' -> cAny .|. cIdent  .|. cLower   -- d
+   '\101' -> cAny .|. cIdent  .|. cLower   -- e
+   '\102' -> cAny .|. cIdent  .|. cLower   -- f
+   '\103' -> cAny .|. cIdent  .|. cLower   -- g
+   '\104' -> cAny .|. cIdent  .|. cLower   -- h
+   '\105' -> cAny .|. cIdent  .|. cLower   -- i
+   '\106' -> cAny .|. cIdent  .|. cLower   -- j
+   '\107' -> cAny .|. cIdent  .|. cLower   -- k
+   '\108' -> cAny .|. cIdent  .|. cLower   -- l
+   '\109' -> cAny .|. cIdent  .|. cLower   -- m
+   '\110' -> cAny .|. cIdent  .|. cLower   -- n
+   '\111' -> cAny .|. cIdent  .|. cLower   -- o
+   '\112' -> cAny .|. cIdent  .|. cLower   -- p
+   '\113' -> cAny .|. cIdent  .|. cLower   -- q
+   '\114' -> cAny .|. cIdent  .|. cLower   -- r
+   '\115' -> cAny .|. cIdent  .|. cLower   -- s
+   '\116' -> cAny .|. cIdent  .|. cLower   -- t
+   '\117' -> cAny .|. cIdent  .|. cLower   -- u
+   '\118' -> cAny .|. cIdent  .|. cLower   -- v
+   '\119' -> cAny .|. cIdent  .|. cLower   -- w
+   '\120' -> cAny .|. cIdent  .|. cLower   -- x
+   '\121' -> cAny .|. cIdent  .|. cLower   -- y
+   '\122' -> cAny .|. cIdent  .|. cLower   -- z
+   '\123' -> cAny                          -- {
+   '\124' -> cAny .|. cSymbol              --  |
+   '\125' -> cAny                          -- }
+   '\126' -> cAny .|. cSymbol              -- ~
+   '\127' -> 0                             -- \177
    _ -> panic ("charType: " ++ show c)