I winged before about NOINLINE pragma on things defined locally in a where clause not doing what I expected: http://www.mail-archive.com/glasgow-haskell-users@haskell.org/msg10338.html Turns out that one was fixed in ghc HEAD. I've got another similar one which is not working as I expect in 6.6 or in head from 1st March. This example is from an experimental re-implementation of the Put monad in Data.Binary: write :: Int -> (Ptr Word8 -> IO ()) -> Put () write !n body = Put $ \c buf@(Buffer fp o u l) -> if n <= l then write' c fp o u l else write' (flushOld c n fp o u) (newBuffer c n) 0 0 0 where {-# NOINLINE write' #-} write' c !fp !o !u !l = -- warning: this is a tad hardcore B.inlinePerformIO (withForeignPtr fp (\p -> body $! (p `plusPtr` (o+u)))) `seq` c () (Buffer fp o (u+n) (l-n)) {-# INLINE [1] write #-} Then we use it with things like word8 :: Word8 -> Put () word8 !w = write 1 (pokeWord8 w) pokeWord8 :: Word8 -> Ptr Word8 -> IO () pokeWord8 w p = poke p w Then there's a rule so that things like: foo :: Word8 -> Put () foo !n = do word8 n word8 (n+1) word8 (n+17) get turned into a single call to write. Anyway, the point is that when we look at the stg/core we see that in write above, the write' has been inlined at the two call sites where as I want both branches of the if test to make calls to write'. The code is here: http://haskell.org/~duncan/binary/PutMonad.hs http://haskell.org/~duncan/binary/PutTest.hs the stg from ghc-6.6 is: http://haskell.org/~duncan/binary/PutTest.stg with ghc head from 1st March the result is different but still inlines write' in both branches. Duncan
Duncan, I implemented this a couple of weeks ago but forgot to push it. Now INLINE pragmas survive across interface files. I hope it's useful. Simon | -----Original Message----- | From: glasgow-haskell-users-bounces@haskell.org [mailto:glasgow-haskell-users-bounces@haskell.org] On | Behalf Of Duncan Coutts | Sent: 14 March 2007 11:59 | To: glasgow-haskell-users@haskell.org | Subject: noinline in where clauses again | | I winged before about NOINLINE pragma on things defined locally in a | where clause not doing what I expected: | | http://www.mail-archive.com/glasgow-haskell-users@haskell.org/msg10338.html | | Turns out that one was fixed in ghc HEAD. | | I've got another similar one which is not working as I expect in 6.6 or | in head from 1st March. | | This example is from an experimental re-implementation of the Put monad | in Data.Binary: | | write :: Int -> (Ptr Word8 -> IO ()) -> Put () | write !n body = Put $ \c buf@(Buffer fp o u l) -> | if n <= l | then write' c fp o u l | else write' (flushOld c n fp o u) (newBuffer c n) 0 0 0 | | where {-# NOINLINE write' #-} | write' c !fp !o !u !l = | -- warning: this is a tad hardcore | B.inlinePerformIO | (withForeignPtr fp | (\p -> body $! (p `plusPtr` (o+u)))) | `seq` c () (Buffer fp o (u+n) (l-n)) | {-# INLINE [1] write #-} | | Then we use it with things like | | word8 :: Word8 -> Put () | word8 !w = write 1 (pokeWord8 w) | | pokeWord8 :: Word8 -> Ptr Word8 -> IO () | pokeWord8 w p = poke p w | | Then there's a rule so that things like: | | foo :: Word8 -> Put () | foo !n = do | word8 n | word8 (n+1) | word8 (n+17) | | get turned into a single call to write. | | Anyway, the point is that when we look at the stg/core we see that in | write above, the write' has been inlined at the two call sites where as | I want both branches of the if test to make calls to write'. | | The code is here: | http://haskell.org/~duncan/binary/PutMonad.hs | http://haskell.org/~duncan/binary/PutTest.hs | | the stg from ghc-6.6 is: | http://haskell.org/~duncan/binary/PutTest.stg | | with ghc head from 1st March the result is different but still inlines | write' in both branches. | | Duncan | | _______________________________________________ | Glasgow-haskell-users mailing list | Glasgow-haskell-users@haskell.org | http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
On Wed, 2007-04-25 at 08:56 +0100, Simon Peyton-Jones wrote:
Duncan,
I implemented this a couple of weeks ago but forgot to push it. Now INLINE pragmas survive across interface files. I hope it's useful.
Fantastic, thanks Simon. I'll try it out in Data.Binary in the next few days and report back. I'm not expecting performance improvements from it but it should reduce code size by not inlining a copy of this local function into the slow path of the binary read/write. Duncan
participants (2)
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Duncan Coutts -
Simon Peyton-Jones