mirror of
https://github.com/GrammaticalFramework/gf-core.git
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143 lines
4.0 KiB
Haskell
143 lines
4.0 KiB
Haskell
----------------------------------------------------------------------
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-- |
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-- Module : BackOpt
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-- Maintainer : AR
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-- Stability : (stable)
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-- Portability : (portable)
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--
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-- > CVS $Date: 2005/04/21 16:21:33 $
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-- > CVS $Author: bringert $
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-- > CVS $Revision: 1.6 $
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--
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-- Optimizations on GF source code: sharing, parametrization, value sets.
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--
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-- optimization: sharing branches in tables. AR 25\/4\/2003.
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-- following advice of Josef Svenningsson
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-----------------------------------------------------------------------------
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module GF.Compile.BackOpt (shareModule, OptSpec, shareOpt, paramOpt, valOpt, allOpt) where
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import GF.Grammar.Grammar
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import GF.Infra.Ident
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import qualified GF.Grammar.Macros as C
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import GF.Grammar.PrGrammar (prt)
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import GF.Data.Operations
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import Data.List
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import qualified GF.Infra.Modules as M
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import qualified Data.ByteString.Char8 as BS
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type OptSpec = [Integer] ---
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doOptFactor :: OptSpec -> Bool
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doOptFactor opt = elem 2 opt
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doOptValues :: OptSpec -> Bool
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doOptValues opt = elem 3 opt
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shareOpt :: OptSpec
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shareOpt = []
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paramOpt :: OptSpec
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paramOpt = [2]
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valOpt :: OptSpec
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valOpt = [3]
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allOpt :: OptSpec
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allOpt = [2,3]
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shareModule :: OptSpec -> (Ident, SourceModInfo) -> (Ident, SourceModInfo)
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shareModule opt (i,m) = case m of
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M.ModMod (M.Module mt st fs me ops js) ->
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(i,M.ModMod (M.Module mt st fs me ops (mapTree (shareInfo opt) js)))
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_ -> (i,m)
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shareInfo opt (c, CncCat ty (Yes t) m) = (c,CncCat ty (Yes (shareOptim opt c t)) m)
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shareInfo opt (c, CncFun kxs (Yes t) m) = (c,CncFun kxs (Yes (shareOptim opt c t)) m)
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shareInfo opt (c, ResOper ty (Yes t)) = (c,ResOper ty (Yes (shareOptim opt c t)))
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shareInfo _ i = i
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-- the function putting together optimizations
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shareOptim :: OptSpec -> Ident -> Term -> Term
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shareOptim opt c
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| doOptFactor opt && doOptValues opt = values . factor c 0
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| doOptFactor opt = share . factor c 0
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| doOptValues opt = values
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| otherwise = share
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-- we need no counter to create new variable names, since variables are
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-- local to tables (only true in GFC) ---
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share :: Term -> Term
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share t = case t of
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T ty@(TComp _) cs -> shareT ty [(p, share v) | (p, v) <- cs]
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_ -> C.composSafeOp share t
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where
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shareT ty = finalize ty . groupC . sortC
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sortC :: [(Patt,Term)] -> [(Patt,Term)]
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sortC = sortBy $ \a b -> compare (snd a) (snd b)
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groupC :: [(Patt,Term)] -> [[(Patt,Term)]]
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groupC = groupBy $ \a b -> snd a == snd b
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finalize :: TInfo -> [[(Patt,Term)]] -> Term
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finalize ty css = TSh ty [(map fst ps, t) | ps@((_,t):_) <- css]
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-- do even more: factor parametric branches
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factor :: Ident -> Int -> Term -> Term
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factor c i t = case t of
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T _ [_] -> t
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T _ [] -> t
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T (TComp ty) cs ->
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T (TTyped ty) $ factors i [(p, factor c (i+1) v) | (p, v) <- cs]
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_ -> C.composSafeOp (factor c i) t
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where
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factors i psvs = -- we know psvs has at least 2 elements
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let p = qqIdent c i
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vs' = map (mkFun p) psvs
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in if allEqs vs'
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then mkCase p vs'
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else psvs
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mkFun p (patt, val) = replace (C.patt2term patt) (Vr p) val
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allEqs (v:vs) = all (==v) vs
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mkCase p (v:_) = [(PV p, v)]
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--- we hope this will be fresh and don't check... in GFC would be safe
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qqIdent c i = identC (BS.pack ("q_" ++ prt c ++ "__" ++ show i))
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-- we need to replace subterms
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replace :: Term -> Term -> Term -> Term
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replace old new trm = case trm of
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-- these are the important cases, since they can correspond to patterns
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QC _ _ | trm == old -> new
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App t ts | trm == old -> new
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App t ts -> App (repl t) (repl ts)
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R _ | isRec && trm == old -> new
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_ -> C.composSafeOp repl trm
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where
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repl = replace old new
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isRec = case trm of
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R _ -> True
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_ -> False
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-- It is very important that this is performed only after case
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-- expansion since otherwise the order and number of values can
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-- be incorrect. Guaranteed by the TComp flag.
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values :: Term -> Term
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values t = case t of
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T ty [(ps,t)] -> T ty [(ps,values t)] -- don't destroy parametrization
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T (TComp ty) cs -> V ty [values t | (_, t) <- cs]
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_ -> C.composSafeOp values t
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