[GHC] #14741: High-memory usage during compilation using Template Haskell

[GHC]

#14741: High-memory usage during compilation using Template Haskell
-------------------------------------+-------------------------------------
        Reporter:  donatello         |                Owner:  sighingnow
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  8.2.2
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  Compile-time      |  Unknown/Multiple
  performance bug                    |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):  Phab:D4384
       Wiki Page:                    |
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Comment (by sighingnow):

 Further optimization for `pprASCII` needs change `CmmString [Word8]` to
 `CmmString ByteString`.

 I have test the performance of unpacking `ByteString` to [Word8]:


 {{{
 embedFile :: FilePath -> IO [Word8]
 embedFile fp = do
   print fp
   B.unpack <$> B.readFile fp

 main :: IO ()
 main = do
     x' <- {-# SCC "forceRead" #-} (force <$> embedFile "3mb")
     print (length x')
 }}}

 It generates the following prof result:

 {{{
            foldr-test.exe +RTS -p -RTS

         total time  =        0.07 secs   (74 ticks @ 1000 us, 1 processor)
         total alloc = 130,807,344 bytes  (excludes profiling overheads)

 COST CENTRE MODULE SRC                     %time %alloc

 forceRead   Main   foldr-test.hs:44:35-61   67.6  100.0
 MAIN        MAIN   <built-in>               32.4    0.0
 }}}

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14741#comment:8>
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