-- | Atom rule scheduling. module Language.Atom.Scheduling ( schedule , Schedule , reportSchedule ) where import Data.List import Language.Atom.Analysis import Language.Atom.Elaboration import Text.Printf type Schedule = [(Int, Int, [Rule])] -- (period, phase, rules) schedule :: [Rule] -> Schedule schedule rules = concatMap spread periods where -- Algorithm for assigning rules to phases for a given period: -- 1. List the rules by their offsets, highest first. -- 2. If the list is empty, stop. -- 3. Otherwise, take the head of the list and assign its phase as follows: -- find the set of phases containing the minimum number of rules such that -- they are at least as large as the rule's offset. Then take the smallest -- of those phases. -- 4. Go to (2). -- Algorithm properties: for each period, -- A. Each rule is scheduled no earlier than its offset. -- B. The phase with the most rules is the minimum of all possible schedules -- that satisfy (A). -- XXX Check if this is true. -- C. The sum of the difference between between each rule's offset and it's -- scheduled phase is the minimum of all schedules satisfying (A) and (B). spread :: (Int, [Rule]) -> Schedule spread (period, rules) = placeRules (replicate period []) orderedByPhase where orderedByPhase :: [Rule] orderedByPhase = sortBy (\r0 r1 -> compare (rulePhase r1) (rulePhase r0)) rules placeRules :: [[Rule]] -> [Rule] -> [(Int, Int, [Rule])] placeRules ls [] = filter (\(_,_,rls) -> not (null rls)) $ zip3 (repeat period) [0..(period-1)] ls placeRules ls (r:rst) = placeRules (insertAt (lub r ls) r ls) rst lub :: Rule -> [[Rule]] -> Int lub r ls = let minI = rulePhase r lub' i [] = i -- unreachable. Included to prevent missing -- cases ghc warnings. lub' i ls | (head ls) == minimum ls = i | otherwise = lub' (i+1) (tail ls) in lub' minI (drop minI $ map length ls) insertAt :: Int -> Rule -> [[Rule]] -> [[Rule]] insertAt i r ls = (take i ls) ++ ((r:(ls !! i)):(drop (i+1) ls)) periods = foldl grow [] [ (rulePeriod r, r) | r <- rules ] grow :: [(Int, [Rule])] -> (Int, Rule) -> [(Int, [Rule])] grow [] (a, b) = [(a, [b])] grow ((a, bs):rest) (a', b) | a' == a = (a, b : bs) : rest | otherwise = (a, bs) : grow rest (a', b) reportSchedule :: Schedule -> String reportSchedule schedule = concat [ "Rule Scheduling Report\n\n" , "Period Phase Exprs Rule\n" , "------ ----- ----- ----\n" , concatMap reportPeriod schedule , " -----\n" , printf " %5i\n" $ sum $ map ruleComplexity rules , "\n" , "Hierarchical Expression Count\n\n" , " Total Local Rule\n" , " ------ ------ ----\n" , reportUsage "" $ usage rules , "\n" ] where rules = concat $ [ r | (_, _, r) <- schedule ] reportPeriod :: (Int, Int, [Rule]) -> String reportPeriod (period, phase, rules) = concatMap reportRule rules where reportRule :: Rule -> String reportRule rule = printf "%6i %5i %5i %s\n" period phase (ruleComplexity rule) (show rule) data Usage = Usage String Int [Usage] deriving Eq instance Ord Usage where compare (Usage a _ _) (Usage b _ _) = compare a b reportUsage :: String -> Usage -> String reportUsage i node@(Usage name n subs) = printf " %6i %6i %s\n" (totalComplexity node) n (i ++ name) ++ concatMap (reportUsage (" " ++ i)) subs totalComplexity :: Usage -> Int totalComplexity (Usage _ n subs) = n + sum (map totalComplexity subs) usage :: [Rule] -> Usage usage = head . foldl insertUsage [] . map usage' usage' :: Rule -> Usage usage' rule = f $ split $ ruleName rule where f :: [String] -> Usage f [] = undefined f [name] = Usage name (ruleComplexity rule) [] f (name:names) = Usage name 0 [f names] split :: String -> [String] split "" = [] split s = a : if null b then [] else split (tail b) where (a,b) = span (/= '.') s insertUsage :: [Usage] -> Usage -> [Usage] insertUsage [] u = [u] insertUsage (a@(Usage n1 i1 s1) : rest) b@(Usage n2 i2 s2) | n1 == n2 = Usage n1 (max i1 i2) (sort $ foldl insertUsage s1 s2) : rest | otherwise = a : insertUsage rest b