Refactor: delete most of the module FastTypeswip/d1141

This reverses some of the work done in #1405, and goes back to the
assumption that the bootstrap compiler understands GHC-haskell.

In particular:
  * use MagicHash instead of _ILIT and _CLIT
  * pattern matching on I# if possible, instead of using iUnbox
    unnecessarily
  * use Int#/Char#/Addr# instead of the following type synonyms:
    - type FastInt   = Int#
    - type FastChar  = Char#
    - type FastPtr a = Addr#
  * inline the following functions:
    - iBox           = I#
    - cBox           = C#
    - fastChr        = chr#
    - fastOrd        = ord#
    - eqFastChar     = eqChar#
    - shiftLFastInt  = uncheckedIShiftL#
    - shiftR_FastInt = uncheckedIShiftRL#
    - shiftRLFastInt = uncheckedIShiftRL#
  * delete the following unused functions:
    - minFastInt
    - maxFastInt
    - uncheckedIShiftRA#
    - castFastPtr
    - panicDocFastInt and pprPanicFastInt
  * rename panicFastInt back to panic#

These functions remain, since they actually do something:
  * iUnbox
  * bitAndFastInt
  * bitOrFastInt

Test Plan: validate

Reviewers: austin, bgamari

Subscribers: rwbarton

Differential Revision: https://phabricator.haskell.org/D1141

GHC Trac Issues: #1405

1 files changed, 3 insertions, 20 deletions

diff --git a/compiler/utils/StringBuffer.hs b/compiler/utils/StringBuffer.hs
index 570282da57..2e339d8d75 100644
--- a/compiler/utils/StringBuffer.hs
+++ b/compiler/utils/StringBuffer.hs
@@ -6,8 +6,8 @@
 Buffers for scanning string input stored in external arrays.
 -}
 
-{-# LANGUAGE BangPatterns, CPP, MagicHash, UnboxedTuples #-}
-{-# OPTIONS_GHC -O -funbox-strict-fields #-}
+{-# LANGUAGE CPP, MagicHash, UnboxedTuples #-}
+{-# OPTIONS_GHC -O #-}
 -- We always optimise this, otherwise performance of a non-optimised
 -- compiler is severely affected
 
@@ -45,7 +45,6 @@ module StringBuffer
 
 import Encoding
 import FastString
-import FastTypes
 import FastFunctions
 import Outputable
 import Util
@@ -232,26 +231,10 @@ lexemeToFastString (StringBuffer buf _ cur) len =
 
 -- -----------------------------------------------------------------------------
 -- Parsing integer strings in various bases
-{-
-byteOff :: StringBuffer -> Int -> Char
-byteOff (StringBuffer buf _ cur) i =
-  inlinePerformIO $ withForeignPtr buf $ \ptr -> do
---    return $! cBox (indexWord8OffFastPtrAsFastChar
---                         (pUnbox ptr) (iUnbox (cur+i)))
---or
---    w <- peek (ptr `plusPtr` (cur+i))
---    return (unsafeChr (fromIntegral (w::Word8)))
--}
--- | XXX assumes ASCII digits only (by using byteOff)
 parseUnsignedInteger :: StringBuffer -> Int -> Integer -> (Char->Int) -> Integer
 parseUnsignedInteger (StringBuffer buf _ cur) len radix char_to_int
   = inlinePerformIO $ withForeignPtr buf $ \ptr -> return $! let
-    --LOL, in implementations where the indexing needs slow unsafePerformIO,
-    --this is less (not more) efficient than using the IO monad explicitly
-    --here.
-    !ptr' = pUnbox ptr
-    byteOff i = cBox (indexWord8OffFastPtrAsFastChar ptr' (iUnbox (cur + i)))
     go i x | i == len  = x
-           | otherwise = case byteOff i of
+           | otherwise = case fst (utf8DecodeChar (ptr `plusPtr` (cur + i))) of
                char -> go (i + 1) (x * radix + toInteger (char_to_int char))
   in go 0 0