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| author | Ian Lynagh <ian@well-typed.com> | 2012-11-02 22:29:50 +0000 |
|---|---|---|
| committer | Ian Lynagh <ian@well-typed.com> | 2012-11-02 22:29:50 +0000 |
| commit | bc4580c309ce57b642faf9702f8a2891e7313bb9 (patch) | |
| tree | 9c6a99891a5c8e962db362ea4209c1517a724a3b | |
| parent | f2b953f76d1a6f7832179e539c69e47f715daf81 (diff) | |
| download | haskell-bc4580c309ce57b642faf9702f8a2891e7313bb9.tar.gz | |
Whitespace only in specialise/SpecConstr.lhs
| -rw-r--r-- | compiler/specialise/SpecConstr.lhs | 1175 |
1 files changed, 584 insertions, 591 deletions
diff --git a/compiler/specialise/SpecConstr.lhs b/compiler/specialise/SpecConstr.lhs index b2f83deb91..60c40e856f 100644 --- a/compiler/specialise/SpecConstr.lhs +++ b/compiler/specialise/SpecConstr.lhs @@ -9,15 +9,8 @@ ToDo [Nov 2010] \section[SpecConstr]{Specialise over constructors} \begin{code} -{-# OPTIONS -fno-warn-tabs #-} --- The above warning supression flag is a temporary kludge. --- While working on this module you are encouraged to remove it and --- detab the module (please do the detabbing in a separate patch). See --- http://hackage.haskell.org/trac/ghc/wiki/Commentary/CodingStyle#TabsvsSpaces --- for details - module SpecConstr( - specConstrProgram + specConstrProgram #ifdef GHCI , SpecConstrAnnotation(..) #endif @@ -28,28 +21,28 @@ module SpecConstr( import CoreSyn import CoreSubst import CoreUtils -import CoreUnfold ( couldBeSmallEnoughToInline ) -import CoreFVs ( exprsFreeVars ) +import CoreUnfold ( couldBeSmallEnoughToInline ) +import CoreFVs ( exprsFreeVars ) import CoreMonad -import Literal ( litIsLifted ) +import Literal ( litIsLifted ) import HscTypes ( ModGuts(..) ) -import WwLib ( mkWorkerArgs ) +import WwLib ( mkWorkerArgs ) import DataCon -import Coercion hiding( substTy, substCo ) +import Coercion hiding( substTy, substCo ) import Rules -import Type hiding ( substTy ) +import Type hiding ( substTy ) import Id -import MkCore ( mkImpossibleExpr ) +import MkCore ( mkImpossibleExpr ) import Var import VarEnv import VarSet import Name import BasicTypes -import DynFlags ( DynFlags(..) ) -import StaticFlags ( opt_PprStyle_Debug ) -import Maybes ( orElse, catMaybes, isJust, isNothing ) +import DynFlags ( DynFlags(..) ) +import StaticFlags ( opt_PprStyle_Debug ) +import Maybes ( orElse, catMaybes, isJust, isNothing ) import Demand -import DmdAnal ( both ) +import DmdAnal ( both ) import Serialized ( deserializeWithData ) import Util import Pair @@ -58,7 +51,7 @@ import Outputable import FastString import UniqFM import MonadUtils -import Control.Monad ( zipWithM ) +import Control.Monad ( zipWithM ) import Data.List @@ -72,76 +65,76 @@ import GHC.Exts( SpecConstrAnnotation(..) ) \end{code} ----------------------------------------------------- - Game plan + Game plan ----------------------------------------------------- Consider - drop n [] = [] - drop 0 xs = [] - drop n (x:xs) = drop (n-1) xs + drop n [] = [] + drop 0 xs = [] + drop n (x:xs) = drop (n-1) xs After the first time round, we could pass n unboxed. This happens in numerical code too. Here's what it looks like in Core: - drop n xs = case xs of - [] -> [] - (y:ys) -> case n of - I# n# -> case n# of - 0 -> [] - _ -> drop (I# (n# -# 1#)) xs + drop n xs = case xs of + [] -> [] + (y:ys) -> case n of + I# n# -> case n# of + 0 -> [] + _ -> drop (I# (n# -# 1#)) xs Notice that the recursive call has an explicit constructor as argument. Noticing this, we can make a specialised version of drop - - RULE: drop (I# n#) xs ==> drop' n# xs - drop' n# xs = let n = I# n# in ...orig RHS... + RULE: drop (I# n#) xs ==> drop' n# xs + + drop' n# xs = let n = I# n# in ...orig RHS... Now the simplifier will apply the specialisation in the rhs of drop', giving - drop' n# xs = case xs of - [] -> [] - (y:ys) -> case n# of - 0 -> [] - _ -> drop (n# -# 1#) xs + drop' n# xs = case xs of + [] -> [] + (y:ys) -> case n# of + 0 -> [] + _ -> drop (n# -# 1#) xs -Much better! +Much better! We'd also like to catch cases where a parameter is carried along unchanged, but evaluated each time round the loop: - f i n = if i>0 || i>n then i else f (i*2) n + f i n = if i>0 || i>n then i else f (i*2) n Here f isn't strict in n, but we'd like to avoid evaluating it each iteration. In Core, by the time we've w/wd (f is strict in i) we get - f i# n = case i# ># 0 of - False -> I# i# - True -> case n of n' { I# n# -> - case i# ># n# of - False -> I# i# - True -> f (i# *# 2#) n' + f i# n = case i# ># 0 of + False -> I# i# + True -> case n of n' { I# n# -> + case i# ># n# of + False -> I# i# + True -> f (i# *# 2#) n' At the call to f, we see that the argument, n is know to be (I# n#), and n is evaluated elsewhere in the body of f, so we can play the same -trick as above. +trick as above. Note [Reboxing] ~~~~~~~~~~~~~~~ We must be careful not to allocate the same constructor twice. Consider - f p = (...(case p of (a,b) -> e)...p..., - ...let t = (r,s) in ...t...(f t)...) + f p = (...(case p of (a,b) -> e)...p..., + ...let t = (r,s) in ...t...(f t)...) At the recursive call to f, we can see that t is a pair. But we do NOT want to make a specialised copy: - f' a b = let p = (a,b) in (..., ...) + f' a b = let p = (a,b) in (..., ...) because now t is allocated by the caller, then r and s are passed to the recursive call, which allocates the (r,s) pair again. This happens if (a) the argument p is used in other than a case-scrutinsation way. (b) the argument to the call is not a 'fresh' tuple; you have to - look into its unfolding to see that it's a tuple + look into its unfolding to see that it's a tuple Hence the "OR" part of Note [Good arguments] below. @@ -155,16 +148,16 @@ If at the call site the (I# x) was an unfolding, then we'd have to rely on CSE to eliminate the duplicate allocation.... This alternative doesn't look attractive enough to pursue. -ALTERNATIVE 3: ignore the reboxing problem. The trouble is that +ALTERNATIVE 3: ignore the reboxing problem. The trouble is that the conservative reboxing story prevents many useful functions from being specialised. Example: - foo :: Maybe Int -> Int -> Int - foo (Just m) 0 = 0 - foo x@(Just m) n = foo x (n-m) + foo :: Maybe Int -> Int -> Int + foo (Just m) 0 = 0 + foo x@(Just m) n = foo x (n-m) Here the use of 'x' will clearly not require boxing in the specialised function. The strictness analyser has the same problem, in fact. Example: - f p@(a,b) = ... + f p@(a,b) = ... If we pass just 'a' and 'b' to the worker, it might need to rebox the pair to create (a,b). A more sophisticated analysis might figure out precisely the cases in which this could happen, but the strictness @@ -179,25 +172,25 @@ Note [Good arguments] ~~~~~~~~~~~~~~~~~~~~~ So we look for -* A self-recursive function. Ignore mutual recursion for now, +* A self-recursive function. Ignore mutual recursion for now, because it's less common, and the code is simpler for self-recursion. * EITHER - a) At a recursive call, one or more parameters is an explicit + a) At a recursive call, one or more parameters is an explicit constructor application - AND - That same parameter is scrutinised by a case somewhere in + AND + That same parameter is scrutinised by a case somewhere in the RHS of the function OR b) At a recursive call, one or more parameters has an unfolding that is an explicit constructor application - AND - That same parameter is scrutinised by a case somewhere in + AND + That same parameter is scrutinised by a case somewhere in the RHS of the function - AND + AND Those are the only uses of the parameter (see Note [Reboxing]) @@ -206,11 +199,11 @@ What to abstract over There's a bit of a complication with type arguments. If the call site looks like - f p = ...f ((:) [a] x xs)... + f p = ...f ((:) [a] x xs)... then our specialised function look like - f_spec x xs = let p = (:) [a] x xs in ....as before.... + f_spec x xs = let p = (:) [a] x xs in ....as before.... This only makes sense if either a) the type variable 'a' is in scope at the top of f, or @@ -220,7 +213,7 @@ Actually, (a) may hold for value arguments too, in which case we may not want to pass them. Supose 'x' is in scope at f's defn, but xs is not. Then we'd like - f_spec xs = let p = (:) [a] x xs in ....as before.... + f_spec xs = let p = (:) [a] x xs in ....as before.... Similarly (b) may hold too. If x is already an argument at the call, no need to pass it again. @@ -228,17 +221,17 @@ call, no need to pass it again. Finally, if 'a' is not in scope at the call site, we could abstract it as we do the term variables: - f_spec a x xs = let p = (:) [a] x xs in ...as before... + f_spec a x xs = let p = (:) [a] x xs in ...as before... So the grand plan is: - * abstract the call site to a constructor-only pattern - e.g. C x (D (f p) (g q)) ==> C s1 (D s2 s3) + * abstract the call site to a constructor-only pattern + e.g. C x (D (f p) (g q)) ==> C s1 (D s2 s3) - * Find the free variables of the abstracted pattern + * Find the free variables of the abstracted pattern - * Pass these variables, less any that are in scope at - the fn defn. But see Note [Shadowing] below. + * Pass these variables, less any that are in scope at + the fn defn. But see Note [Shadowing] below. NOTICE that we only abstract over variables that are not in scope, @@ -253,13 +246,13 @@ that are bound between the usage site and the definition site; or (more seriously) may be bound to something different at the definition site. For example: - f x = letrec g y v = let x = ... - in ...(g (a,b) x)... + f x = letrec g y v = let x = ... + in ...(g (a,b) x)... -Since 'x' is in scope at the call site, we may make a rewrite rule that +Since 'x' is in scope at the call site, we may make a rewrite rule that looks like - RULE forall a,b. g (a,b) x = ... -But this rule will never match, because it's really a different 'x' at + RULE forall a,b. g (a,b) x = ... +But this rule will never match, because it's really a different 'x' at the call site -- and that difference will be manifest by the time the simplifier gets to it. [A worry: the simplifier doesn't *guarantee* no-shadowing, so perhaps it may not be distinct?] @@ -292,9 +285,9 @@ It produces \ (ww_sme :: GHC.Prim.Int#) (w_smg :: GHC.Base.Int -> GHC.Base.Int) -> case ww_sme of ds_Xlw { __DEFAULT -> - case w_smg (GHC.Base.I# ds_Xlw) of w1_Xmo { GHC.Base.I# ww1_Xmz -> - T.$wfoo ww1_Xmz lvl_rmV - }; + case w_smg (GHC.Base.I# ds_Xlw) of w1_Xmo { GHC.Base.I# ww1_Xmz -> + T.$wfoo ww1_Xmz lvl_rmV + }; 0 -> 0 } @@ -310,7 +303,7 @@ When is this worth it? Call the constant 'lvl' Also do this is if the function has RULES? -Also +Also Note [Specialising for lambda parameters] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ @@ -327,14 +320,14 @@ explicit lambda as the argument: \ (ww_sm8 :: GHC.Prim.Int#) (w_sma :: GHC.Base.Int -> GHC.Base.Int) -> case ww_sm8 of ds_Xlr { __DEFAULT -> - case w_sma (GHC.Base.I# ds_Xlr) of w1_Xmf { GHC.Base.I# ww1_Xmq -> - T.$wfoo - ww1_Xmq - (\ (n_ad3 :: GHC.Base.Int) -> - case n_ad3 of wild_alB { GHC.Base.I# x_alA -> - GHC.Base.I# (GHC.Prim.-# x_alA ds_Xlr) - }) - }; + case w_sma (GHC.Base.I# ds_Xlr) of w1_Xmf { GHC.Base.I# ww1_Xmq -> + T.$wfoo + ww1_Xmq + (\ (n_ad3 :: GHC.Base.Int) -> + case n_ad3 of wild_alB { GHC.Base.I# x_alA -> + GHC.Base.I# (GHC.Prim.-# x_alA ds_Xlr) + }) + }; 0 -> 0 } @@ -351,7 +344,7 @@ Looks cool, but probably rare...but it might be easy to implement. Note [SpecConstr for casts] ~~~~~~~~~~~~~~~~~~~~~~~~~~~ -Consider +Consider data family T a :: * data instance T Int = T Int @@ -360,8 +353,8 @@ Consider go (T 0) = 0 go (T n) = go (T (n-1)) -The recursive call ends up looking like - go (T (I# ...) `cast` g) +The recursive call ends up looking like + go (T (I# ...) `cast` g) So we want to spot the construtor application inside the cast. That's why we have the Cast case in argToPat @@ -384,7 +377,7 @@ If we start with the RHSs of 'foo', we get lots and lots of specialisations, most of which are not needed. But if we start with the (single) call in the rhs of 'bar' we get exactly one fully-specialised copy, and all the recursive calls go to this fully-specialised copy. Indeed, the original -function is later collected as dead code. This is very important in +function is later collected as dead code. This is very important in specialising the loops arising from stream fusion, for example in NDP where we were getting literally hundreds of (mostly unused) specialisations of a local function. @@ -397,7 +390,7 @@ ones, such as letrec foo x y = ....foo... in map foo xs then we will end up calling the un-specialised function, so then we *should* -use the calls in the un-specialised RHS as seeds. We call these "boring +use the calls in the un-specialised RHS as seeds. We call these "boring call patterns, and callsToPats reports if it finds any of these. @@ -523,7 +516,7 @@ that we have ForceSpecConstr, this NoSpecConstr is probably redundant. (Used only for PArray.) ----------------------------------------------------- - Stuff not yet handled + Stuff not yet handled ----------------------------------------------------- Here are notes arising from Roman's work that I don't want to lose. @@ -543,16 +536,16 @@ looks like a boxed use of the argument. A pity. $wfoo_sFw :: GHC.Prim.Int# -> T.T GHC.Base.Int -> GHC.Prim.Int# $wfoo_sFw = \ (ww_sFo [Just L] :: GHC.Prim.Int#) (w_sFq [Just L] :: T.T GHC.Base.Int) -> - case ww_sFo of ds_Xw6 [Just L] { - __DEFAULT -> - case GHC.Prim.remInt# ds_Xw6 2 of wild1_aEF [Dead Just A] { - __DEFAULT -> $wfoo_sFw (GHC.Prim.-# ds_Xw6 1) w_sFq; - 0 -> - case w_sFq of wild_Xy [Just L] { T.T n_ad5 [Just U(L)] -> - case n_ad5 of wild1_aET [Just A] { GHC.Base.I# y_aES [Just L] -> - $wfoo_sFw (GHC.Prim.-# ds_Xw6 y_aES) wild_Xy - } } }; - 0 -> 0 + case ww_sFo of ds_Xw6 [Just L] { + __DEFAULT -> + case GHC.Prim.remInt# ds_Xw6 2 of wild1_aEF [Dead Just A] { + __DEFAULT -> $wfoo_sFw (GHC.Prim.-# ds_Xw6 1) w_sFq; + 0 -> + case w_sFq of wild_Xy [Just L] { T.T n_ad5 [Just U(L)] -> + case n_ad5 of wild1_aET [Just A] { GHC.Base.I# y_aES [Just L] -> + $wfoo_sFw (GHC.Prim.-# ds_Xw6 y_aES) wild_Xy + } } }; + 0 -> 0 Example 2 ~~~~~~~~~ @@ -573,34 +566,34 @@ a strict tuple. Before SpecConstr, we have GHC.Base.Int) -> case ww_sFU of ds_Xws [Just L] { __DEFAULT -> - case GHC.Prim.remInt# ds_Xws 2 of wild1_aEZ [Dead Just A] { - __DEFAULT -> - case ww_sFW of tpl_B2 [Just L] { T.T a_sFo [Just A] -> - $wfoo_sG3 (GHC.Prim.-# ds_Xws 1) tpl_B2 -- $wfoo1 - }; - 0 -> - case ww_sFW of wild_XB [Just A] { T.T n_ad7 [Just S(L)] -> - case n_ad7 of wild1_aFd [Just L] { GHC.Base.I# y_aFc [Just L] -> - $wfoo_sG3 (GHC.Prim.-# ds_Xws y_aFc) wild_XB -- $wfoo2 - } } }; + case GHC.Prim.remInt# ds_Xws 2 of wild1_aEZ [Dead Just A] { + __DEFAULT -> + case ww_sFW of tpl_B2 [Just L] { T.T a_sFo [Just A] -> + $wfoo_sG3 (GHC.Prim.-# ds_Xws 1) tpl_B2 -- $wfoo1 + }; + 0 -> + case ww_sFW of wild_XB [Just A] { T.T n_ad7 [Just S(L)] -> + case n_ad7 of wild1_aFd [Just L] { GHC.Base.I# y_aFc [Just L] -> + $wfoo_sG3 (GHC.Prim.-# ds_Xws y_aFc) wild_XB -- $wfoo2 + } } }; 0 -> 0 } We get two specialisations: "SC:$wfoo1" [0] __forall {a_sFB :: GHC.Base.Int sc_sGC :: GHC.Prim.Int#} - Foo.$wfoo sc_sGC (Foo.T @ GHC.Base.Int a_sFB) - = Foo.$s$wfoo1 a_sFB sc_sGC ; + Foo.$wfoo sc_sGC (Foo.T @ GHC.Base.Int a_sFB) + = Foo.$s$wfoo1 a_sFB sc_sGC ; "SC:$wfoo2" [0] __forall {y_aFp :: GHC.Prim.Int# sc_sGC :: GHC.Prim.Int#} - Foo.$wfoo sc_sGC (Foo.T @ GHC.Base.Int (GHC.Base.I# y_aFp)) - = Foo.$s$wfoo y_aFp sc_sGC ; + Foo.$wfoo sc_sGC (Foo.T @ GHC.Base.Int (GHC.Base.I# y_aFp)) + = Foo.$s$wfoo y_aFp sc_sGC ; But perhaps the first one isn't good. After all, we know that tpl_B2 is a T (I# x) really, because T is strict and Int has one constructor. (We can't unbox the strict fields, becuase T is polymorphic!) %************************************************************************ -%* * +%* * \subsection{Top level wrapper stuff} -%* * +%* * %************************************************************************ \begin{code} @@ -613,7 +606,7 @@ specConstrProgram guts let binds' = fst $ initUs us (go (initScEnv dflags annos) (mg_binds guts)) return (guts { mg_binds = binds' }) where - go _ [] = return [] + go _ [] = return [] go env (bind:binds) = do (env', bind') <- scTopBind env bind binds' <- go env' binds return (bind' : binds') @@ -621,72 +614,72 @@ specConstrProgram guts %************************************************************************ -%* * +%* * \subsection{Environment: goes downwards} -%* * +%* * %************************************************************************ \begin{code} data ScEnv = SCE { sc_dflags :: DynFlags, - sc_size :: Maybe Int, -- Size threshold - sc_count :: Maybe Int, -- Max # of specialisations for any one fn - -- See Note [Avoiding exponential blowup] + sc_size :: Maybe Int, -- Size threshold + sc_count :: Maybe Int, -- Max # of specialisations for any one fn + -- See Note [Avoiding exponential blowup] sc_force :: Bool, -- Force specialisation? -- See Note [Forcing specialisation] - sc_subst :: Subst, -- Current substitution - -- Maps InIds to OutExprs + sc_subst :: Subst, -- Current substitution + -- Maps InIds to OutExprs - sc_how_bound :: HowBoundEnv, - -- Binds interesting non-top-level variables - -- Domain is OutVars (*after* applying the substitution) + sc_how_bound :: HowBoundEnv, + -- Binds interesting non-top-level variables + -- Domain is OutVars (*after* applying the substitution) - sc_vals :: ValueEnv, - -- Domain is OutIds (*after* applying the substitution) - -- Used even for top-level bindings (but not imported ones) + sc_vals :: ValueEnv, + -- Domain is OutIds (*after* applying the substitution) + -- Used even for top-level bindings (but not imported ones) sc_annotations :: UniqFM SpecConstrAnnotation - } + } --------------------- -- As we go, we apply a substitution (sc_subst) to the current term -type InExpr = CoreExpr -- _Before_ applying the subst +type InExpr = CoreExpr -- _Before_ applying the subst type InVar = Var -type OutExpr = CoreExpr -- _After_ applying the subst +type OutExpr = CoreExpr -- _After_ applying the subst type OutId = Id type OutVar = Var --------------------- -type HowBoundEnv = VarEnv HowBound -- Domain is OutVars +type HowBoundEnv = VarEnv HowBound -- Domain is OutVars --------------------- -type ValueEnv = IdEnv Value -- Domain is OutIds -data Value = ConVal AltCon [CoreArg] -- _Saturated_ constructors - -- The AltCon is never DEFAULT - | LambdaVal -- Inlinable lambdas or PAPs +type ValueEnv = IdEnv Value -- Domain is OutIds +data Value = ConVal AltCon [CoreArg] -- _Saturated_ constructors + -- The AltCon is never DEFAULT + | LambdaVal -- Inlinable lambdas or PAPs instance Outputable Value where ppr (ConVal con args) = ppr con <+> interpp'SP args - ppr LambdaVal = ptext (sLit "<Lambda>") + ppr LambdaVal = ptext (sLit "<Lambda>") --------------------- initScEnv :: DynFlags -> UniqFM SpecConstrAnnotation -> ScEnv initScEnv dflags anns = SCE { sc_dflags = dflags, sc_size = specConstrThreshold dflags, - sc_count = specConstrCount dflags, + sc_count = specConstrCount dflags, sc_force = False, - sc_subst = emptySubst, - sc_how_bound = emptyVarEnv, - sc_vals = emptyVarEnv, + sc_subst = emptySubst, + sc_how_bound = emptyVarEnv, + sc_vals = emptyVarEnv, sc_annotations = anns } -data HowBound = RecFun -- These are the recursive functions for which - -- we seek interesting call patterns +data HowBound = RecFun -- These are the recursive functions for which + -- we seek interesting call patterns - | RecArg -- These are those functions' arguments, or their sub-components; - -- we gather occurrence information for these + | RecArg -- These are those functions' arguments, or their sub-components; + -- we gather occurrence information for these instance Outputable HowBound where ppr RecFun = text "RecFun" @@ -711,10 +704,10 @@ zapScSubst :: ScEnv -> ScEnv zapScSubst env = env { sc_subst = zapSubstEnv (sc_subst env) } extendScInScope :: ScEnv -> [Var] -> ScEnv - -- Bring the quantified variables into scope + -- Bring the quantified variables into scope extendScInScope env qvars = env { sc_subst = extendInScopeList (sc_subst env) qvars } - -- Extend the substitution + -- Extend the substitution extendScSubst :: ScEnv -> Var -> OutExpr -> ScEnv extendScSubst env var expr = env { sc_subst = extendSubst (sc_subst env) var expr } @@ -724,18 +717,18 @@ extendScSubstList env prs = env { sc_subst = extendSubstList (sc_subst env) prs extendHowBound :: ScEnv -> [Var] -> HowBound -> ScEnv extendHowBound env bndrs how_bound = env { sc_how_bound = extendVarEnvList (sc_how_bound env) - [(bndr,how_bound) | bndr <- bndrs] } + [(bndr,how_bound) | bndr <- bndrs] } extendBndrsWith :: HowBound -> ScEnv -> [Var] -> (ScEnv, [Var]) -extendBndrsWith how_bound env bndrs +extendBndrsWith how_bound env bndrs = (env { sc_subst = subst', sc_how_bound = hb_env' }, bndrs') where (subst', bndrs') = substBndrs (sc_subst env) bndrs - hb_env' = sc_how_bound env `extendVarEnvList` - [(bndr,how_bound) | bndr <- bndrs'] + hb_env' = sc_how_bound env `extendVarEnvList` + [(bndr,how_bound) | bndr <- bndrs'] extendBndrWith :: HowBound -> ScEnv -> Var -> (ScEnv, Var) -extendBndrWith how_bound env bndr +extendBndrWith how_bound env bndr = (env { sc_subst = subst', sc_how_bound = hb_env' }, bndr') where (subst', bndr') = substBndr (sc_subst env) bndr @@ -743,13 +736,13 @@ extendBndrWith how_bound env bndr extendRecBndrs :: ScEnv -> [Var] -> (ScEnv, [Var]) extendRecBndrs env bndrs = (env { sc_subst = subst' }, bndrs') - where - (subst', bndrs') = substRecBndrs (sc_subst env) bndrs + where + (subst', bndrs') = substRecBndrs (sc_subst env) bndrs extendBndr :: ScEnv -> Var -> (ScEnv, Var) extendBndr env bndr = (env { sc_subst = subst' }, bndr') - where - (subst', bndr') = substBndr (sc_subst env) bndr + where + (subst', bndr') = substBndr (sc_subst env) bndr extendValEnv :: ScEnv -> Id -> Maybe Value -> ScEnv extendValEnv env _ Nothing = env @@ -757,8 +750,8 @@ extendValEnv env id (Just cv) = env { sc_vals = extendVarEnv (sc_vals env) id cv extendCaseBndrs :: ScEnv -> OutExpr -> OutId -> AltCon -> [Var] -> (ScEnv, [Var]) -- When we encounter --- case scrut of b --- C x y -> ... +-- case scrut of b +-- C x y -> ... -- we want to bind b, to (C x y) -- NB1: Extends only the sc_vals part of the envt -- NB2: Kill the dead-ness info on the pattern binders x,y, since @@ -768,7 +761,7 @@ extendCaseBndrs env scrut case_bndr con alt_bndrs where live_case_bndr = not (isDeadBinder case_bndr) env1 | Var v <- scrut = extendValEnv env v cval - | otherwise = env -- See Note [Add scrutinee to ValueEnv too] + | otherwise = env -- See Note [Add scrutinee to ValueEnv too] env2 | live_case_bndr = extendValEnv env1 case_bndr cval | otherwise = env1 @@ -778,25 +771,25 @@ extendCaseBndrs env scrut case_bndr con alt_bndrs = alt_bndrs cval = case con of - DEFAULT -> Nothing - LitAlt {} -> Just (ConVal con []) - DataAlt {} -> Just (ConVal con vanilla_args) - where - vanilla_args = map Type (tyConAppArgs (idType case_bndr)) ++ - varsToCoreExprs alt_bndrs - - zap v | isTyVar v = v -- See NB2 above + DEFAULT -> Nothing + LitAlt {} -> Just (ConVal con []) + DataAlt {} -> Just (ConVal con vanilla_args) + where + vanilla_args = map Type (tyConAppArgs (idType case_bndr)) ++ + varsToCoreExprs alt_bndrs + + zap v | isTyVar v = v -- See NB2 above | otherwise = zapIdOccInfo v decreaseSpecCount :: ScEnv -> Int -> ScEnv -- See Note [Avoiding exponential blowup] -decreaseSpecCount env n_specs +decreaseSpecCount env n_specs = env { sc_count = case sc_count env of Nothing -> Nothing Just n -> Just (n `div` (n_specs + 1)) } - -- The "+1" takes account of the original function; - -- See Note [Avoiding exponential blowup] + -- The "+1" takes account of the original function; + -- See Note [Avoiding exponential blowup] --------------------------------------------------- -- See Note [SpecConstrAnnotation] @@ -852,7 +845,7 @@ will have a binding for y, and for c c -> I# v BUT that's not enough! Looking at the call (f y) we see that y is pair (a,b), but we also need to know what 'b' is. -So in extendCaseBndrs we must *also* add the binding +So in extendCaseBndrs we must *also* add the binding b -> I# v else we lose a useful specialisation for f. This is necessary even though the simplifier has systematically replaced uses of 'x' with 'y' @@ -865,12 +858,12 @@ The sc_count field of the ScEnv says how many times we are prepared to duplicate a single function. But we must take care with recursive specialiations. Consider - let $j1 = let $j2 = let $j3 = ... - in + let $j1 = let $j2 = let $j3 = ... + in ...$j3... - in + in ...$j2... - in + in ...$j1... If we specialise $j1 then in each specialisation (as well as the original) @@ -883,25 +876,25 @@ copies we are making at this level, including the original. %************************************************************************ -%* * +%* * \subsection{Usage information: flows upwards} -%* * +%* * %************************************************************************ \begin{code} data ScUsage = SCU { - scu_calls :: CallEnv, -- Calls - -- The functions are a subset of the - -- RecFuns in the ScEnv + scu_calls :: CallEnv, -- Calls + -- The functions are a subset of the + -- RecFuns in the ScEnv - scu_occs :: !(IdEnv ArgOcc) -- Information on argument occurrences - } -- The domain is OutIds + scu_occs :: !(IdEnv ArgOcc) -- Information on argument occurrences + } -- The domain is OutIds type CallEnv = IdEnv [Call] type Call = (ValueEnv, [CoreArg]) - -- The arguments of the call, together with the - -- env giving the constructor bindings at the call site + -- The arguments of the call, together with the + -- env giving the constructor bindings at the call site nullUsage :: ScUsage nullUsage = SCU { scu_calls = emptyVarEnv, scu_occs = emptyVarEnv } @@ -911,7 +904,7 @@ combineCalls = plusVarEnv_C (++) combineUsage :: ScUsage -> ScUsage -> ScUsage combineUsage u1 u2 = SCU { scu_calls = combineCalls (scu_calls u1) (scu_calls u2), - scu_occs = plusVarEnv_C combineOcc (scu_occs u1) (scu_occs u2) } + scu_occs = plusVarEnv_C combineOcc (scu_occs u1) (scu_occs u2) } combineUsages :: [ScUsage] -> ScUsage combineUsages [] = nullUsage @@ -922,13 +915,13 @@ lookupOccs (SCU { scu_calls = sc_calls, scu_occs = sc_occs }) bndrs = (SCU {scu_calls = sc_calls, scu_occs = delVarEnvList sc_occs bndrs}, [lookupVarEnv sc_occs b `orElse` NoOcc | b <- bndrs]) -data ArgOcc = NoOcc -- Doesn't occur at all; or a type argument - | UnkOcc -- Used in some unknown way +data ArgOcc = NoOcc -- Doesn't occur at all; or a type argument + | UnkOcc -- Used in some unknown way - | ScrutOcc -- See Note [ScrutOcc] + | ScrutOcc -- See Note [ScrutOcc] (DataConEnv [ArgOcc]) -- How the sub-components are used -type DataConEnv a = UniqFM a -- Keyed by DataCon +type DataConEnv a = UniqFM a -- Keyed by DataCon {- Note [ScrutOcc] ~~~~~~~~~~~~~~~~~~~ @@ -941,17 +934,17 @@ is *only* taken apart or applied. where (subs :: UniqFM [ArgOcc]) gives usage of the *pattern-bound* components, The domain of the UniqFM is the Unique of the data constructor -The [ArgOcc] is the occurrences of the *pattern-bound* components +The [ArgOcc] is the occurrences of the *pattern-bound* components of the data structure. E.g. - data T a = forall b. MkT a b (b->a) + data T a = forall b. MkT a b (b->a) A pattern binds b, x::a, y::b, z::b->a, but not 'a'! -} instance Outputable ArgOcc where ppr (ScrutOcc xs) = ptext (sLit "scrut-occ") <> ppr xs - ppr UnkOcc = ptext (sLit "unk-occ") - ppr NoOcc = ptext (sLit "no-occ") + ppr UnkOcc = ptext (sLit "unk-occ") + ppr NoOcc = ptext (sLit "no-occ") evalScrutOcc :: ArgOcc evalScrutOcc = ScrutOcc emptyUFM @@ -961,11 +954,11 @@ evalScrutOcc = ScrutOcc emptyUFM -- in the overall result, even if it's also used in a boxed way -- This might be too agressive; see Note [Reboxing] Alternative 3 combineOcc :: ArgOcc -> ArgOcc -> ArgOcc -combineOcc NoOcc occ = occ -combineOcc occ NoOcc = occ +combineOcc NoOcc occ = occ +combineOcc occ NoOcc = occ combineOcc (ScrutOcc xs) (ScrutOcc ys) = ScrutOcc (plusUFM_C combineOccs xs ys) combineOcc UnkOcc (ScrutOcc ys) = ScrutOcc ys -combineOcc (ScrutOcc xs) UnkOcc = ScrutOcc xs +combineOcc (ScrutOcc xs) UnkOcc = ScrutOcc xs combineOcc UnkOcc UnkOcc = UnkOcc combineOccs :: [ArgOcc] -> [ArgOcc] -> [ArgOcc] @@ -978,15 +971,15 @@ setScrutOcc env usg (Cast e _) occ = setScrutOcc env usg e occ setScrutOcc env usg (Tick _ e) occ = setScrutOcc env usg e occ setScrutOcc env usg (Var v) occ | Just RecArg <- lookupHowBound env v = usg { scu_occs = extendVarEnv (scu_occs usg) v occ } - | otherwise = usg -setScrutOcc _env usg _other _occ -- Catch-all - = usg + | otherwise = usg +setScrutOcc _env usg _other _occ -- Catch-all + = usg \end{code} %************************************************************************ -%* * +%* * \subsection{The main recursive function} -%* * +%* * %************************************************************************ The main recursive function gathers up usage information, and @@ -994,15 +987,15 @@ creates specialised versions of functions. \begin{code} scExpr, scExpr' :: ScEnv -> CoreExpr -> UniqSM (ScUsage, CoreExpr) - -- The unique supply is needed when we invent - -- a new name for the specialised function and its args + -- The unique supply is needed when we invent + -- a new name for the specialised function and its args scExpr env e = scExpr' env e scExpr' env (Var v) = case scSubstId env v of - Var v' -> return (mkVarUsage env v' [], Var v') - e' -> scExpr (zapScSubst env) e' + Var v' -> return (mkVarUsage env v' [], Var v') + e' -> scExpr (zapScSubst env) e' scExpr' env (Type t) = return (nullUsage, Type (scSubstTy env t)) scExpr' env (Coercion c) = return (nullUsage, Coercion (scSubstCo env c)) @@ -1016,98 +1009,98 @@ scExpr' env (Lam b e) = do let (env', b') = extendBndr env b (usg, e') <- scExpr env' e return (usg, Lam b' e') -scExpr' env (Case scrut b ty alts) - = do { (scrut_usg, scrut') <- scExpr env scrut - ; case isValue (sc_vals env) scrut' of - Just (ConVal con args) -> sc_con_app con args scrut' - _other -> sc_vanilla scrut_usg scrut' - } +scExpr' env (Case scrut b ty alts) + = do { (scrut_usg, scrut') <- scExpr env scrut + ; case isValue (sc_vals env) scrut' of + Just (ConVal con args) -> sc_con_app con args scrut' + _other -> sc_vanilla scrut_usg scrut' + } where - sc_con_app con args scrut' -- Known constructor; simplify - = do { let (_, bs, rhs) = findAlt con alts - `orElse` (DEFAULT, [], mkImpossibleExpr ty) - alt_env' = extendScSubstList env ((b,scrut') : bs `zip` trimConArgs con args) - ; scExpr alt_env' rhs } - - sc_vanilla scrut_usg scrut' -- Normal case + sc_con_app con args scrut' -- Known constructor; simplify + = do { let (_, bs, rhs) = findAlt con alts + `orElse` (DEFAULT, [], mkImpossibleExpr ty) + alt_env' = extendScSubstList env ((b,scrut') : bs `zip` trimConArgs con args) + ; scExpr alt_env' rhs } + + sc_vanilla scrut_usg scrut' -- Normal case = do { let (alt_env,b') = extendBndrWith RecArg env b - -- Record RecArg for the components + -- Record RecArg for the components - ; (alt_usgs, alt_occs, alts') - <- mapAndUnzip3M (sc_alt alt_env scrut' b') alts + ; (alt_usgs, alt_occs, alts') + <- mapAndUnzip3M (sc_alt alt_env scrut' b') alts - ; let scrut_occ = foldr combineOcc NoOcc alt_occs - scrut_usg' = setScrutOcc env scrut_usg scrut' scrut_occ - -- The combined usage of the scrutinee is given - -- by scrut_occ, which is passed to scScrut, which - -- in turn treats a bare-variable scrutinee specially + ; let scrut_occ = foldr combineOcc NoOcc alt_occs + scrut_usg' = setScrutOcc env scrut_usg scrut' scrut_occ + -- The combined usage of the scrutinee is given + -- by scrut_occ, which is passed to scScrut, which + -- in turn treats a bare-variable scrutinee specially - ; return (foldr combineUsage scrut_usg' alt_usgs, - Case scrut' b' (scSubstTy env ty) alts') } + ; return (foldr combineUsage scrut_usg' alt_usgs, + Case scrut' b' (scSubstTy env ty) alts') } sc_alt env scrut' b' (con,bs,rhs) = do { let (env1, bs1) = extendBndrsWith RecArg env bs - (env2, bs2) = extendCaseBndrs env1 scrut' b' con bs1 - ; (usg, rhs') <- scExpr env2 rhs - ; let (usg', b_occ:arg_occs) = lookupOccs usg (b':bs2) - scrut_occ = case con of - DataAlt dc -> ScrutOcc (unitUFM dc arg_occs) - _ -> ScrutOcc emptyUFM - ; return (usg', b_occ `combineOcc` scrut_occ, (con, bs2, rhs')) } + (env2, bs2) = extendCaseBndrs env1 scrut' b' con bs1 + ; (usg, rhs') <- scExpr env2 rhs + ; let (usg', b_occ:arg_occs) = lookupOccs usg (b':bs2) + scrut_occ = case con of + DataAlt dc -> ScrutOcc (unitUFM dc arg_occs) + _ -> ScrutOcc emptyUFM + ; return (usg', b_occ `combineOcc` scrut_occ, (con, bs2, rhs')) } scExpr' env (Let (NonRec bndr rhs) body) - | isTyVar bndr -- Type-lets may be created by doBeta + | isTyVar bndr -- Type-lets may be created by doBeta = scExpr' (extendScSubst env bndr rhs) body - | otherwise - = do { let (body_env, bndr') = extendBndr env bndr - ; (rhs_usg, rhs_info) <- scRecRhs env (bndr',rhs) + | otherwise + = do { let (body_env, bndr') = extendBndr env bndr + ; (rhs_usg, rhs_info) <- scRecRhs env (bndr',rhs) - ; let body_env2 = extendHowBound body_env [bndr'] RecFun - -- Note [Local let bindings] - RI _ rhs' _ _ _ = rhs_info + ; let body_env2 = extendHowBound body_env [bndr'] RecFun + -- Note [Local let bindings] + RI _ rhs' _ _ _ = rhs_info body_env3 = extendValEnv body_env2 bndr' (isValue (sc_vals env) rhs') - ; (body_usg, body') <- scExpr body_env3 body + ; (body_usg, body') <- scExpr body_env3 body -- NB: For non-recursive bindings we inherit sc_force flag from -- the parent function (see Note [Forcing specialisation]) - ; (spec_usg, specs) <- specialise env - (scu_calls body_usg) - rhs_info + ; (spec_usg, specs) <- specialise env + (scu_calls body_usg) + rhs_info (SI [] 0 (Just rhs_usg)) - ; return (body_usg { scu_calls = scu_calls body_usg `delVarEnv` bndr' } - `combineUsage` rhs_usg `combineUsage` spec_usg, - mkLets [NonRec b r | (b,r) <- specInfoBinds rhs_info specs] body') - } + ; return (body_usg { scu_calls = scu_calls body_usg `delVarEnv` bndr' } + `combineUsage` rhs_usg `combineUsage` spec_usg, + mkLets [NonRec b r | (b,r) <- specInfoBinds rhs_info specs] body') + } -- A *local* recursive group: see Note [Local recursive groups] scExpr' env (Let (Rec prs) body) - = do { let (bndrs,rhss) = unzip prs - (rhs_env1,bndrs') = extendRecBndrs env bndrs - rhs_env2 = extendHowBound rhs_env1 bndrs' RecFun + = do { let (bndrs,rhss) = unzip prs + (rhs_env1,bndrs') = extendRecBndrs env bndrs + rhs_env2 = extendHowBound rhs_env1 bndrs' RecFun force_spec = any (forceSpecBndr env) bndrs' -- Note [Forcing specialisation] - ; (rhs_usgs, rhs_infos) <- mapAndUnzipM (scRecRhs rhs_env2) (bndrs' `zip` rhss) - ; (body_usg, body') <- scExpr rhs_env2 body + ; (rhs_usgs, rhs_infos) <- mapAndUnzipM (scRecRhs rhs_env2) (bndrs' `zip` rhss) + ; (body_usg, body') <- scExpr rhs_env2 body - -- NB: start specLoop from body_usg - ; (spec_usg, specs) <- specLoop (scForce rhs_env2 force_spec) + -- NB: start specLoop from body_usg + ; (spec_usg, specs) <- specLoop (scForce rhs_env2 force_spec) (scu_calls body_usg) rhs_infos nullUsage - [SI [] 0 (Just usg) | usg <- rhs_usgs] - -- Do not unconditionally generate specialisations from rhs_usgs - -- Instead use them only if we find an unspecialised call - -- See Note [Local recursive groups] + [SI [] 0 (Just usg) | usg <- rhs_usgs] + -- Do not unconditionally generate specialisations from rhs_usgs + -- Instead use them only if we find an unspecialised call + -- See Note [Local recursive groups] - ; let rhs_usg = combineUsages rhs_usgs - all_usg = spec_usg `combineUsage` rhs_usg `combineUsage` body_usg + ; let rhs_usg = combineUsages rhs_usgs + all_usg = spec_usg `combineUsage` rhs_usg `combineUsage` body_usg bind' = Rec (concat (zipWith specInfoBinds rhs_infos specs)) - ; return (all_usg { scu_calls = scu_calls all_usg `delVarEnvList` bndrs' }, - Let bind' body') } + ; return (all_usg { scu_calls = scu_calls all_usg `delVarEnvList` bndrs' }, + Let bind' body') } \end{code} Note [Local let bindings] @@ -1130,45 +1123,45 @@ harmful. I'm not sure. \begin{code} scApp :: ScEnv -> (InExpr, [InExpr]) -> UniqSM (ScUsage, CoreExpr) -scApp env (Var fn, args) -- Function is a variable +scApp env (Var fn, args) -- Function is a variable = ASSERT( not (null args) ) - do { args_w_usgs <- mapM (scExpr env) args - ; let (arg_usgs, args') = unzip args_w_usgs - arg_usg = combineUsages arg_usgs - ; case scSubstId env fn of - fn'@(Lam {}) -> scExpr (zapScSubst env) (doBeta fn' args') - -- Do beta-reduction and try again - - Var fn' -> return (arg_usg `combineUsage` mkVarUsage env fn' args', + do { args_w_usgs <- mapM (scExpr env) args + ; let (arg_usgs, args') = unzip args_w_usgs + arg_usg = combineUsages arg_usgs + ; case scSubstId env fn of + fn'@(Lam {}) -> scExpr (zapScSubst env) (doBeta fn' args') + -- Do beta-reduction and try again + + Var fn' -> return (arg_usg `combineUsage` mkVarUsage env fn' args', mkApps (Var fn') args') - other_fn' -> return (arg_usg, mkApps other_fn' args') } - -- NB: doing this ignores any usage info from the substituted - -- function, but I don't think that matters. If it does - -- we can fix it. + other_fn' -> return (arg_usg, mkApps other_fn' args') } + -- NB: doing this ignores any usage info from the substituted + -- function, but I don't think that matters. If it does + -- we can fix it. where doBeta :: OutExpr -> [OutExpr] -> OutExpr -- ToDo: adjust for System IF doBeta (Lam bndr body) (arg : args) = Let (NonRec bndr arg) (doBeta body args) - doBeta fn args = mkApps fn args + doBeta fn args = mkApps fn args --- The function is almost always a variable, but not always. +-- The function is almost always a variable, but not always. -- In particular, if this pass follows float-in, --- which it may, we can get --- (let f = ...f... in f) arg1 arg2 +-- which it may, we can get +-- (let f = ...f... in f) arg1 arg2 scApp env (other_fn, args) - = do { (fn_usg, fn') <- scExpr env other_fn - ; (arg_usgs, args') <- mapAndUnzipM (scExpr env) args - ; return (combineUsages arg_usgs `combineUsage` fn_usg, mkApps fn' args') } + = do { (fn_usg, fn') <- scExpr env other_fn + ; (arg_usgs, args') <- mapAndUnzipM (scExpr env) args + ; return (combineUsages arg_usgs `combineUsage` fn_usg, mkApps fn' args') } ---------------------- mkVarUsage :: ScEnv -> Id -> [CoreExpr] -> ScUsage mkVarUsage env fn args = case lookupHowBound env fn of - Just RecFun -> SCU { scu_calls = unitVarEnv fn [(sc_vals env, args)] - , scu_occs = emptyVarEnv } - Just RecArg -> SCU { scu_calls = emptyVarEnv - , scu_occs = unitVarEnv fn arg_occ } + Just RecFun -> SCU { scu_calls = unitVarEnv fn [(sc_vals env, args)] + , scu_occs = emptyVarEnv } + Just RecArg -> SCU { scu_calls = emptyVarEnv + , scu_occs = unitVarEnv fn arg_occ } Nothing -> nullUsage where -- I rather think we could use UnkOcc all the time @@ -1181,116 +1174,116 @@ scTopBind env (Rec prs) | Just threshold <- sc_size env , not force_spec , not (all (couldBeSmallEnoughToInline (sc_dflags env) threshold) rhss) - -- No specialisation - = do { let (rhs_env,bndrs') = extendRecBndrs env bndrs - ; (_, rhss') <- mapAndUnzipM (scExpr rhs_env) rhss - ; return (rhs_env, Rec (bndrs' `zip` rhss')) } - | otherwise -- Do specialisation - = do { let (rhs_env1,bndrs') = extendRecBndrs env bndrs - rhs_env2 = extendHowBound rhs_env1 bndrs' RecFun - - ; (rhs_usgs, rhs_infos) <- mapAndUnzipM (scRecRhs rhs_env2) (bndrs' `zip` rhss) - ; let rhs_usg = combineUsages rhs_usgs - - ; (_, specs) <- specLoop (scForce rhs_env2 force_spec) + -- No specialisation + = do { let (rhs_env,bndrs') = extendRecBndrs env bndrs + ; (_, rhss') <- mapAndUnzipM (scExpr rhs_env) rhss + ; return (rhs_env, Rec (bndrs' `zip` rhss')) } + | otherwise -- Do specialisation + = do { let (rhs_env1,bndrs') = extendRecBndrs env bndrs + rhs_env2 = extendHowBound rhs_env1 bndrs' RecFun + + ; (rhs_usgs, rhs_infos) <- mapAndUnzipM (scRecRhs rhs_env2) (bndrs' `zip` rhss) + ; let rhs_usg = combineUsages rhs_usgs + + ; (_, specs) <- specLoop (scForce rhs_env2 force_spec) (scu_calls rhs_usg) rhs_infos nullUsage - [SI [] 0 Nothing | _ <- bndrs] + [SI [] 0 Nothing | _ <- bndrs] - ; return (rhs_env1, -- For the body of the letrec, delete the RecFun business - Rec (concat (zipWith specInfoBinds rhs_infos specs))) } + ; return (rhs_env1, -- For the body of the letrec, delete the RecFun business + Rec (concat (zipWith specInfoBinds rhs_infos specs))) } where (bndrs,rhss) = unzip prs force_spec = any (forceSpecBndr env) bndrs -- Note [Forcing specialisation] scTopBind env (NonRec bndr rhs) - = do { (_, rhs') <- scExpr env rhs - ; let (env1, bndr') = extendBndr env bndr - env2 = extendValEnv env1 bndr' (isValue (sc_vals env) rhs') - ; return (env2, NonRec bndr' rhs') } + = do { (_, rhs') <- scExpr env rhs + ; let (env1, bndr') = extendBndr env bndr + env2 = extendValEnv env1 bndr' (isValue (sc_vals env) rhs') + ; return (env2, NonRec bndr' rhs') } ---------------------- scRecRhs :: ScEnv -> (OutId, InExpr) -> UniqSM (ScUsage, RhsInfo) scRecRhs env (bndr,rhs) - = do { let (arg_bndrs,body) = collectBinders rhs - (body_env, arg_bndrs') = extendBndrsWith RecArg env arg_bndrs - ; (body_usg, body') <- scExpr body_env body - ; let (rhs_usg, arg_occs) = lookupOccs body_usg arg_bndrs' - ; return (rhs_usg, RI bndr (mkLams arg_bndrs' body') + = do { let (arg_bndrs,body) = collectBinders rhs + (body_env, arg_bndrs') = extendBndrsWith RecArg env arg_bndrs + ; (body_usg, body') <- scExpr body_env body + ; let (rhs_usg, arg_occs) = lookupOccs body_usg arg_bndrs' + ; return (rhs_usg, RI bndr (mkLams arg_bndrs' body') arg_bndrs body arg_occs) } - -- The arg_occs says how the visible, - -- lambda-bound binders of the RHS are used - -- (including the TyVar binders) - -- Two pats are the same if they match both ways + -- The arg_occs says how the visible, + -- lambda-bound binders of the RHS are used + -- (including the TyVar binders) + -- Two pats are the same if they match both ways ---------------------- specInfoBinds :: RhsInfo -> SpecInfo -> [(Id,CoreExpr)] specInfoBinds (RI fn new_rhs _ _ _) (SI specs _ _) - = [(id,rhs) | OS _ _ id rhs <- specs] ++ - -- First the specialised bindings + = [(id,rhs) | OS _ _ id rhs <- specs] ++ + -- First the specialised bindings [(fn `addIdSpecialisations` rules, new_rhs)] - -- And now the original binding + -- And now the original binding where rules = [r | OS _ r _ _ <- specs] \end{code} %************************************************************************ -%* * - The specialiser itself -%* * +%* * + The specialiser itself +%* * %************************************************************************ \begin{code} -data RhsInfo = RI OutId -- The binder - OutExpr -- The new RHS - [InVar] InExpr -- The *original* RHS (\xs.body) - -- Note [Specialise original body] - [ArgOcc] -- Info on how the xs occur in body +data RhsInfo = RI OutId -- The binder + OutExpr -- The new RHS + [InVar] InExpr -- The *original* RHS (\xs.body) + -- Note [Specialise original body] + [ArgOcc] -- Info on how the xs occur in body -data SpecInfo = SI [OneSpec] -- The specialisations we have generated +data SpecInfo = SI [OneSpec] -- The specialisations we have generated - Int -- Length of specs; used for numbering them + Int -- Length of specs; used for numbering them - (Maybe ScUsage) -- Just cs => we have not yet used calls in the - -- from calls in the *original* RHS as - -- seeds for new specialisations; - -- if you decide to do so, here is the - -- RHS usage (which has not yet been - -- unleashed) - -- Nothing => we have - -- See Note [Local recursive groups] + (Maybe ScUsage) -- Just cs => we have not yet used calls in the + -- from calls in the *original* RHS as + -- seeds for new specialisations; + -- if you decide to do so, here is the + -- RHS usage (which has not yet been + -- unleashed) + -- Nothing => we have + -- See Note [Local recursive groups] - -- One specialisation: Rule plus definition -data OneSpec = OS CallPat -- Call pattern that generated this specialisation - CoreRule -- Rule connecting original id with the specialisation - OutId OutExpr -- Spec id + its rhs + -- One specialisation: Rule plus definition +data OneSpec = OS CallPat -- Call pattern that generated this specialisation + CoreRule -- Rule connecting original id with the specialisation + OutId OutExpr -- Spec id + its rhs specLoop :: ScEnv - -> CallEnv - -> [RhsInfo] - -> ScUsage -> [SpecInfo] -- One per binder; acccumulating parameter - -> UniqSM (ScUsage, [SpecInfo]) -- ...ditto... + -> CallEnv + -> [RhsInfo] + -> ScUsage -> [SpecInfo] -- One per binder; acccumulating parameter + -> UniqSM (ScUsage, [SpecInfo]) -- ...ditto... specLoop env all_calls rhs_infos usg_so_far specs_so_far - = do { specs_w_usg <- zipWithM (specialise env all_calls) rhs_infos specs_so_far - ; let (new_usg_s, all_specs) = unzip specs_w_usg - new_usg = combineUsages new_usg_s - new_calls = scu_calls new_usg - all_usg = usg_so_far `combineUsage` new_usg - ; if isEmptyVarEnv new_calls then - return (all_usg, all_specs) - else - specLoop env new_calls rhs_infos all_usg all_specs } - -specialise + = do { specs_w_usg <- zipWithM (specialise env all_calls) rhs_infos specs_so_far + ; let (new_usg_s, all_specs) = unzip specs_w_usg + new_usg = combineUsages new_usg_s + new_calls = scu_calls new_usg + all_usg = usg_so_far `combineUsage` new_usg + ; if isEmptyVarEnv new_calls then + return (all_usg, all_specs) + else + specLoop env new_calls rhs_infos all_usg all_specs } + +specialise :: ScEnv - -> CallEnv -- Info on calls + -> CallEnv -- Info on calls -> RhsInfo - -> SpecInfo -- Original RHS plus patterns dealt with - -> UniqSM (ScUsage, SpecInfo) -- New specialised versions and their usage + -> SpecInfo -- Original RHS plus patterns dealt with + -> UniqSM (ScUsage, SpecInfo) -- New specialised versions and their usage -- Note: this only generates *specialised* bindings -- The original binding is added by specInfoBinds @@ -1299,126 +1292,126 @@ specialise -- So when we make a specialised copy of the RHS, we're starting -- from an RHS whose nested functions have been optimised already. -specialise env bind_calls (RI fn _ arg_bndrs body arg_occs) +specialise env bind_calls (RI fn _ arg_bndrs body arg_occs) spec_info@(SI specs spec_count mb_unspec) | not (isBottomingId fn) -- Note [Do not specialise diverging functions] - , not (isNeverActive (idInlineActivation fn)) -- See Note [Transfer activation] - , notNull arg_bndrs -- Only specialise functions + , not (isNeverActive (idInlineActivation fn)) -- See Note [Transfer activation] + , notNull arg_bndrs -- Only specialise functions , Just all_calls <- lookupVarEnv bind_calls fn - = do { (boring_call, pats) <- callsToPats env specs arg_occs all_calls --- ; pprTrace "specialise" (vcat [ ppr fn <+> text "with" <+> int (length pats) <+> text "good patterns" + = do { (boring_call, pats) <- callsToPats env specs arg_occs all_calls +-- ; pprTrace "specialise" (vcat [ ppr fn <+> text "with" <+> int (length pats) <+> text "good patterns" -- , text "arg_occs" <+> ppr arg_occs --- , text "calls" <+> ppr all_calls --- , text "good pats" <+> ppr pats]) $ --- return () +-- , text "calls" <+> ppr all_calls +-- , text "good pats" <+> ppr pats]) $ +-- return () - -- Bale out if too many specialisations - ; let n_pats = length pats + -- Bale out if too many specialisations + ; let n_pats = length pats spec_count' = n_pats + spec_count - ; case sc_count env of - Just max | not (sc_force env) && spec_count' > max - -> if (debugIsOn || opt_PprStyle_Debug) -- Suppress this scary message for - then pprTrace "SpecConstr" msg $ -- ordinary users! Trac #5125 + ; case sc_count env of + Just max | not (sc_force env) && spec_count' > max + -> if (debugIsOn || opt_PprStyle_Debug) -- Suppress this scary message for + then pprTrace "SpecConstr" msg $ -- ordinary users! Trac #5125 return (nullUsage, spec_info) else return (nullUsage, spec_info) - where - msg = vcat [ sep [ ptext (sLit "Function") <+> quotes (ppr fn) - , nest 2 (ptext (sLit "has") <+> + where + msg = vcat [ sep [ ptext (sLit "Function") <+> quotes (ppr fn) + , nest 2 (ptext (sLit "has") <+> speakNOf spec_count' (ptext (sLit "call pattern")) <> comma <+> ptext (sLit "but the limit is") <+> int max) ] - , ptext (sLit "Use -fspec-constr-count=n to set the bound") - , extra ] - extra | not opt_PprStyle_Debug = ptext (sLit "Use -dppr-debug to see specialisations") - | otherwise = ptext (sLit "Specialisations:") <+> ppr (pats ++ [p | OS p _ _ _ <- specs]) + , ptext (sLit "Use -fspec-constr-count=n to set the bound") + , extra ] + extra | not opt_PprStyle_Debug = ptext (sLit "Use -dppr-debug to see specialisations") + | otherwise = ptext (sLit "Specialisations:") <+> ppr (pats ++ [p | OS p _ _ _ <- specs]) - _normal_case -> do { + _normal_case -> do { let spec_env = decreaseSpecCount env n_pats - ; (spec_usgs, new_specs) <- mapAndUnzipM (spec_one spec_env fn arg_bndrs body) - (pats `zip` [spec_count..]) - -- See Note [Specialise original body] - - ; let spec_usg = combineUsages spec_usgs - (new_usg, mb_unspec') - = case mb_unspec of - Just rhs_usg | boring_call -> (spec_usg `combineUsage` rhs_usg, Nothing) - _ -> (spec_usg, mb_unspec) - - ; return (new_usg, SI (new_specs ++ specs) spec_count' mb_unspec') } } + ; (spec_usgs, new_specs) <- mapAndUnzipM (spec_one spec_env fn arg_bndrs body) + (pats `zip` [spec_count..]) + -- See Note [Specialise original body] + + ; let spec_usg = combineUsages spec_usgs + (new_usg, mb_unspec') + = case mb_unspec of + Just rhs_usg | boring_call -> (spec_usg `combineUsage` rhs_usg, Nothing) + _ -> (spec_usg, mb_unspec) + + ; return (new_usg, SI (new_specs ++ specs) spec_count' mb_unspec') } } | otherwise - = return (nullUsage, spec_info) -- The boring case + = return (nullUsage, spec_info) -- The boring case --------------------- spec_one :: ScEnv - -> OutId -- Function - -> [InVar] -- Lambda-binders of RHS; should match patterns - -> InExpr -- Body of the original function - -> (CallPat, Int) - -> UniqSM (ScUsage, OneSpec) -- Rule and binding + -> OutId -- Function + -> [InVar] -- Lambda-binders of RHS; should match patterns + -> InExpr -- Body of the original function + -> (CallPat, Int) + -> UniqSM (ScUsage, OneSpec) -- Rule and binding -- spec_one creates a specialised copy of the function, together -- with a rule for using it. I'm very proud of how short this -- function is, considering what it does :-). -{- +{- Example - - In-scope: a, x::a + + In-scope: a, x::a f = /\b \y::[(a,b)] -> ....f (b,c) ((:) (a,(b,c)) (x,v) (h w))... - [c::*, v::(b,c) are presumably bound by the (...) part] + [c::*, v::(b,c) are presumably bound by the (...) part] ==> f_spec = /\ b c \ v::(b,c) hw::[(a,(b,c))] -> - (...entire body of f...) [b -> (b,c), - y -> ((:) (a,(b,c)) (x,v) hw)] - - RULE: forall b::* c::*, -- Note, *not* forall a, x - v::(b,c), - hw::[(a,(b,c))] . - - f (b,c) ((:) (a,(b,c)) (x,v) hw) = f_spec b c v hw + (...entire body of f...) [b -> (b,c), + y -> ((:) (a,(b,c)) (x,v) hw)] + + RULE: forall b::* c::*, -- Note, *not* forall a, x + v::(b,c), + hw::[(a,(b,c))] . + + f (b,c) ((:) (a,(b,c)) (x,v) hw) = f_spec b c v hw -} spec_one env fn arg_bndrs body (call_pat@(qvars, pats), rule_number) - = do { spec_uniq <- getUniqueUs + = do { spec_uniq <- getUniqueUs ; let spec_env = extendScSubstList (extendScInScope env qvars) - (arg_bndrs `zip` pats) - fn_name = idName fn - fn_loc = nameSrcSpan fn_name - spec_occ = mkSpecOcc (nameOccName fn_name) - dflags = sc_dflags env - rule_name = mkFastString ("SC:" ++ showSDoc dflags (ppr fn <> int rule_number)) - spec_name = mkInternalName spec_uniq spec_occ fn_loc --- ; pprTrace "{spec_one" (ppr (sc_count env) <+> ppr fn <+> ppr pats <+> text "-->" <+> ppr spec_name) $ --- return () - - -- Specialise the body - ; (spec_usg, spec_body) <- scExpr spec_env body - --- ; pprTrace "done spec_one}" (ppr fn) $ --- return () - - -- And build the results - ; let spec_id = mkLocalId spec_name (mkPiTypes spec_lam_args body_ty) - `setIdStrictness` spec_str -- See Note [Transfer strictness] - `setIdArity` count isId spec_lam_args - spec_str = calcSpecStrictness fn spec_lam_args pats - (spec_lam_args, spec_call_args) = mkWorkerArgs qvars body_ty - -- Usual w/w hack to avoid generating - -- a spec_rhs of unlifted type and no args + (arg_bndrs `zip` pats) + fn_name = idName fn + fn_loc = nameSrcSpan fn_name + spec_occ = mkSpecOcc (nameOccName fn_name) + dflags = sc_dflags env + rule_name = mkFastString ("SC:" ++ showSDoc dflags (ppr fn <> int rule_number)) + spec_name = mkInternalName spec_uniq spec_occ fn_loc +-- ; pprTrace "{spec_one" (ppr (sc_count env) <+> ppr fn <+> ppr pats <+> text "-->" <+> ppr spec_name) $ +-- return () + + -- Specialise the body + ; (spec_usg, spec_body) <- scExpr spec_env body + +-- ; pprTrace "done spec_one}" (ppr fn) $ +-- return () + + -- And build the results + ; let spec_id = mkLocalId spec_name (mkPiTypes spec_lam_args body_ty) + `setIdStrictness` spec_str -- See Note [Transfer strictness] + `setIdArity` count isId spec_lam_args + spec_str = calcSpecStrictness fn spec_lam_args pats + (spec_lam_args, spec_call_args) = mkWorkerArgs qvars body_ty + -- Usual w/w hack to avoid generating + -- a spec_rhs of unlifted type and no args spec_rhs = mkLams spec_lam_args spec_body - body_ty = exprType spec_body - rule_rhs = mkVarApps (Var spec_id) spec_call_args + body_ty = exprType spec_body + rule_rhs = mkVarApps (Var spec_id) spec_call_args inline_act = idInlineActivation fn - rule = mkRule True {- Auto -} True {- Local -} + rule = mkRule True {- Auto -} True {- Local -} rule_name inline_act fn_name qvars pats rule_rhs - -- See Note [Transfer activation] - ; return (spec_usg, OS call_pat rule spec_id spec_rhs) } + -- See Note [Transfer activation] + ; return (spec_usg, OS call_pat rule spec_id spec_rhs) } -calcSpecStrictness :: Id -- The original function +calcSpecStrictness :: Id -- The original function -> [Var] -> [CoreExpr] -- Call pattern - -> StrictSig -- Strictness of specialised thing + -> StrictSig -- Strictness of specialised thing -- See Note [Transfer strictness] calcSpecStrictness fn qvars pats = StrictSig (mkTopDmdType spec_dmds TopRes) @@ -1435,8 +1428,8 @@ calcSpecStrictness fn qvars pats go_one env d (Var v) = extendVarEnv_C both env v d go_one env (Box d) e = go_one env d e - go_one env (Eval (Prod ds)) e - | (Var _, args) <- collectArgs e = go env ds args + go_one env (Eval (Prod ds)) e + | (Var _, args) <- collectArgs e = go env ds args go_one env _ _ = env \end{code} @@ -1477,7 +1470,7 @@ the specialised one. Suppose, for example and a RULE f (a:as) b = f_spec a as b Now we want f_spec to have strictess LLS, otherwise we'll use call-by-need -when calling f_spec instead of call-by-value. And that can result in +when calling f_spec instead of call-by-value. And that can result in unbounded worsening in space (cf the classic foldl vs foldl') See Trac #3437 for a good example. @@ -1486,9 +1479,9 @@ The function calcSpecStrictness performs the calculation. %************************************************************************ -%* * +%* * \subsection{Argument analysis} -%* * +%* * %************************************************************************ This code deals with analysing call-site arguments to see whether @@ -1501,63 +1494,63 @@ we quantify over. Clearly over 'a' and 'x', but what about any type variables free in x's type? In fact we don't need to worry about them because (f @a) can only be a well-typed application if its type is compatible with x, so any variables free in x's type must be free in (f @a), and hence either be gathered -via 'a' itself, or be in scope at f's defn. Hence we just take +via 'a' itself, or be in scope at f's defn. Hence we just take (exprsFreeVars pats). -BUT phantom type synonyms can mess this reasoning up, +BUT phantom type synonyms can mess this reasoning up, eg x::T b with type T b = Int -So we apply expandTypeSynonyms to the bound Ids. +So we apply expandTypeSynonyms to the bound Ids. See Trac # 5458. Yuk. \begin{code} -type CallPat = ([Var], [CoreExpr]) -- Quantified variables and arguments +type CallPat = ([Var], [CoreExpr]) -- Quantified variables and arguments callsToPats :: ScEnv -> [OneSpec] -> [ArgOcc] -> [Call] -> UniqSM (Bool, [CallPat]) - -- Result has no duplicate patterns, - -- nor ones mentioned in done_pats - -- Bool indicates that there was at least one boring pattern + -- Result has no duplicate patterns, + -- nor ones mentioned in done_pats + -- Bool indicates that there was at least one boring pattern callsToPats env done_specs bndr_occs calls - = do { mb_pats <- mapM (callToPats env bndr_occs) calls + = do { mb_pats <- mapM (callToPats env bndr_occs) calls - ; let good_pats :: [CallPat] - good_pats = catMaybes mb_pats - done_pats = [p | OS p _ _ _ <- done_specs] - is_done p = any (samePat p) done_pats + ; let good_pats :: [CallPat] + good_pats = catMaybes mb_pats + done_pats = [p | OS p _ _ _ <- done_specs] + is_done p = any (samePat p) done_pats - ; return (any isNothing mb_pats, - filterOut is_done (nubBy samePat good_pats)) } + ; return (any isNothing mb_pats, + filterOut is_done (nubBy samePat good_pats)) } callToPats :: ScEnv -> [ArgOcc] -> Call -> UniqSM (Maybe CallPat) - -- The [Var] is the variables to quantify over in the rule - -- Type variables come first, since they may scope - -- over the following term variables - -- The [CoreExpr] are the argument patterns for the rule + -- The [Var] is the variables to quantify over in the rule + -- Type variables come first, since they may scope + -- over the following term variables + -- The [CoreExpr] are the argument patterns for the rule callToPats env bndr_occs (con_env, args) - | length args < length bndr_occs -- Check saturated + | length args < length bndr_occs -- Check saturated = return Nothing | otherwise - = do { let in_scope = substInScope (sc_subst env) - ; (interesting, pats) <- argsToPats env in_scope con_env args bndr_occs - ; let pat_fvs = varSetElems (exprsFreeVars pats) - in_scope_vars = getInScopeVars in_scope - qvars = filterOut (`elemVarSet` in_scope_vars) pat_fvs - -- Quantify over variables that are not in sccpe - -- at the call site - -- See Note [Free type variables of the qvar types] - -- See Note [Shadowing] at the top - - (tvs, ids) = partition isTyVar qvars - qvars' = tvs ++ map sanitise ids - -- Put the type variables first; the type of a term - -- variable may mention a type variable - - sanitise id = id `setIdType` expandTypeSynonyms (idType id) - -- See Note [Free type variables of the qvar types] - - ; -- pprTrace "callToPats" (ppr args $$ ppr prs $$ ppr bndr_occs) $ - if interesting - then return (Just (qvars', pats)) - else return Nothing } + = do { let in_scope = substInScope (sc_subst env) + ; (interesting, pats) <- argsToPats env in_scope con_env args bndr_occs + ; let pat_fvs = varSetElems (exprsFreeVars pats) + in_scope_vars = getInScopeVars in_scope + qvars = filterOut (`elemVarSet` in_scope_vars) pat_fvs + -- Quantify over variables that are not in sccpe + -- at the call site + -- See Note [Free type variables of the qvar types] + -- See Note [Shadowing] at the top + + (tvs, ids) = partition isTyVar qvars + qvars' = tvs ++ map sanitise ids + -- Put the type variables first; the type of a term + -- variable may mention a type variable + + sanitise id = id `setIdType` expandTypeSynonyms (idType id) + -- See Note [Free type variables of the qvar types] + + ; -- pprTrace "callToPats" (ppr args $$ ppr prs $$ ppr bndr_occs) $ + if interesting + then return (Just (qvars', pats)) + else return Nothing } -- argToPat takes an actual argument, and returns an abstracted -- version, consisting of just the "constructor skeleton" of the @@ -1566,45 +1559,45 @@ callToPats env bndr_occs (con_env, args) -- C a (D (f x) (g y)) ==> C p1 (D p2 p3) argToPat :: ScEnv - -> InScopeSet -- What's in scope at the fn defn site - -> ValueEnv -- ValueEnv at the call site - -> CoreArg -- A call arg (or component thereof) - -> ArgOcc - -> UniqSM (Bool, CoreArg) + -> InScopeSet -- What's in scope at the fn defn site + -> ValueEnv -- ValueEnv at the call site + -> CoreArg -- A call arg (or component thereof) + -> ArgOcc + -> UniqSM (Bool, CoreArg) --- Returns (interesting, pat), +-- Returns (interesting, pat), -- where pat is the pattern derived from the argument --- interesting=True if the pattern is non-trivial (not a variable or type) --- E.g. x:xs --> (True, x:xs) --- f xs --> (False, w) where w is a fresh wildcard --- (f xs, 'c') --> (True, (w, 'c')) where w is a fresh wildcard --- \x. x+y --> (True, \x. x+y) --- lvl7 --> (True, lvl7) if lvl7 is bound --- somewhere further out +-- interesting=True if the pattern is non-trivial (not a variable or type) +-- E.g. x:xs --> (True, x:xs) +-- f xs --> (False, w) where w is a fresh wildcard +-- (f xs, 'c') --> (True, (w, 'c')) where w is a fresh wildcard +-- \x. x+y --> (True, \x. x+y) +-- lvl7 --> (True, lvl7) if lvl7 is bound +-- somewhere further out argToPat _env _in_scope _val_env arg@(Type {}) _arg_occ = return (False, arg) - + argToPat env in_scope val_env (Tick _ arg) arg_occ = argToPat env in_scope val_env arg arg_occ - -- Note [Notes in call patterns] - -- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ - -- Ignore Notes. In particular, we want to ignore any InlineMe notes - -- Perhaps we should not ignore profiling notes, but I'm going to - -- ride roughshod over them all for now. - --- See Note [Notes in RULE matching] in Rules + -- Note [Notes in call patterns] + -- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + -- Ignore Notes. In particular, we want to ignore any InlineMe notes + -- Perhaps we should not ignore profiling notes, but I'm going to + -- ride roughshod over them all for now. + --- See Note [Notes in RULE matching] in Rules argToPat env in_scope val_env (Let _ arg) arg_occ = argToPat env in_scope val_env arg arg_occ - -- See Note [Matching lets] in Rule.lhs - -- Look through let expressions - -- e.g. f (let v = rhs in (v,w)) - -- Here we can specialise for f (v,w) - -- because the rule-matcher will look through the let. + -- See Note [Matching lets] in Rule.lhs + -- Look through let expressions + -- e.g. f (let v = rhs in (v,w)) + -- Here we can specialise for f (v,w) + -- because the rule-matcher will look through the let. {- Disabled; see Note [Matching cases] in Rule.lhs argToPat env in_scope val_env (Case scrut _ _ [(_, _, rhs)]) arg_occ - | exprOkForSpeculation scrut -- See Note [Matching cases] in Rule.hhs + | exprOkForSpeculation scrut -- See Note [Matching cases] in Rule.hhs = argToPat env in_scope val_env rhs arg_occ -} @@ -1613,29 +1606,29 @@ argToPat env in_scope val_env (Cast arg co) arg_occ -- can lead to identity coercions = argToPat env in_scope val_env arg arg_occ | not (ignoreType env ty2) - = do { (interesting, arg') <- argToPat env in_scope val_env arg arg_occ - ; if not interesting then - wildCardPat ty2 - else do - { -- Make a wild-card pattern for the coercion - uniq <- getUniqueUs - ; let co_name = mkSysTvName uniq (fsLit "sg") - co_var = mkCoVar co_name (mkCoercionType ty1 ty2) - ; return (interesting, Cast arg' (mkCoVarCo co_var)) } } + = do { (interesting, arg') <- argToPat env in_scope val_env arg arg_occ + ; if not interesting then + wildCardPat ty2 + else do + { -- Make a wild-card pattern for the coercion + uniq <- getUniqueUs + ; let co_name = mkSysTvName uniq (fsLit "sg") + co_var = mkCoVar co_name (mkCoercionType ty1 ty2) + ; return (interesting, Cast arg' (mkCoVarCo co_var)) } } where Pair ty1 ty2 = coercionKind co - -{- Disabling lambda specialisation for now - It's fragile, and the spec_loop can be infinite + +{- Disabling lambda specialisation for now + It's fragile, and the spec_loop can be infinite argToPat in_scope val_env arg arg_occ | is_value_lam arg = return (True, arg) where - is_value_lam (Lam v e) -- Spot a value lambda, even if - | isId v = True -- it is inside a type lambda - | otherwise = is_value_lam e + is_value_lam (Lam v e) -- Spot a value lambda, even if + | isId v = True -- it is inside a type lambda + | otherwise = is_value_lam e is_value_lam other = False -} @@ -1645,21 +1638,21 @@ argToPat env in_scope val_env arg arg_occ | Just (ConVal (DataAlt dc) args) <- isValue val_env arg , not (ignoreDataCon env dc) -- See Note [NoSpecConstr] , Just arg_occs <- mb_scrut dc - = do { let (ty_args, rest_args) = splitAtList (dataConUnivTyVars dc) args + = do { let (ty_args, rest_args) = splitAtList (dataConUnivTyVars dc) args ; (_, args') <- argsToPats env in_scope val_env rest_args arg_occs - ; return (True, + ; return (True, mkConApp dc (ty_args ++ args')) } where mb_scrut dc = case arg_occ of - ScrutOcc bs + ScrutOcc bs | Just occs <- lookupUFM bs dc -> Just (occs) -- See Note [Reboxing] _other | sc_force env -> Just (repeat UnkOcc) | otherwise -> Nothing - -- Check if the argument is a variable that - -- (a) is used in an interesting way in the body - -- (b) we know what its value is + -- Check if the argument is a variable that + -- (a) is used in an interesting way in the body + -- (b) we know what its value is -- In that case it counts as "interesting" argToPat env in_scope val_env (Var v) arg_occ | sc_force env || case arg_occ of { UnkOcc -> False; _other -> True }, -- (a) @@ -1667,30 +1660,30 @@ argToPat env in_scope val_env (Var v) arg_occ not (ignoreType env (varType v)) = return (True, Var v) where - is_value - | isLocalId v = v `elemInScopeSet` in_scope - && isJust (lookupVarEnv val_env v) - -- Local variables have values in val_env - | otherwise = isValueUnfolding (idUnfolding v) - -- Imports have unfoldings - --- I'm really not sure what this comment means --- And by not wild-carding we tend to get forall'd --- variables that are in soope, which in turn can --- expose the weakness in let-matching --- See Note [Matching lets] in Rules - - -- Check for a variable bound inside the function. + is_value + | isLocalId v = v `elemInScopeSet` in_scope + && isJust (lookupVarEnv val_env v) + -- Local variables have values in val_env + | otherwise = isValueUnfolding (idUnfolding v) + -- Imports have unfoldings + +-- I'm really not sure what this comment means +-- And by not wild-carding we tend to get forall'd +-- variables that are in soope, which in turn can +-- expose the weakness in let-matching +-- See Note [Matching lets] in Rules + + -- Check for a variable bound inside the function. -- Don't make a wild-card, because we may usefully share - -- e.g. f a = let x = ... in f (x,x) + -- e.g. f a = let x = ... in f (x,x) -- NB: this case follows the lambda and con-app cases!! -- argToPat _in_scope _val_env (Var v) _arg_occ -- = return (False, Var v) - -- SLPJ : disabling this to avoid proliferation of versions - -- also works badly when thinking about seeding the loop - -- from the body of the let - -- f x y = letrec g z = ... in g (x,y) - -- We don't want to specialise for that *particular* x,y + -- SLPJ : disabling this to avoid proliferation of versions + -- also works badly when thinking about seeding the loop + -- from the body of the let + -- f x y = letrec g z = ... in g (x,y) + -- We don't want to specialise for that *particular* x,y -- The default case: make a wild-card -- We use this for coercions too @@ -1704,8 +1697,8 @@ wildCardPat ty ; return (False, varToCoreExpr id) } argsToPats :: ScEnv -> InScopeSet -> ValueEnv - -> [CoreArg] -> [ArgOcc] -- Should be same length - -> UniqSM (Bool, [CoreArg]) + -> [CoreArg] -> [ArgOcc] -- Should be same length + -> UniqSM (Bool, [CoreArg]) argsToPats env in_scope val_env args occs = do { stuff <- zipWithM (argToPat env in_scope val_env) args occs ; let (interesting_s, args') = unzip stuff @@ -1721,37 +1714,37 @@ isValue _env (Lit lit) isValue env (Var v) | Just stuff <- lookupVarEnv env v - = Just stuff -- You might think we could look in the idUnfolding here - -- but that doesn't take account of which branch of a - -- case we are in, which is the whole point + = Just stuff -- You might think we could look in the idUnfolding here + -- but that doesn't take account of which branch of a + -- case we are in, which is the whole point | not (isLocalId v) && isCheapUnfolding unf = isValue env (unfoldingTemplate unf) where unf = idUnfolding v - -- However we do want to consult the unfolding - -- as well, for let-bound constructors! + -- However we do want to consult the unfolding + -- as well, for let-bound constructors! isValue env (Lam b e) | isTyVar b = case isValue env e of - Just _ -> Just LambdaVal - Nothing -> Nothing + Just _ -> Just LambdaVal + Nothing -> Nothing | otherwise = Just LambdaVal -isValue _env expr -- Maybe it's a constructor application +isValue _env expr -- Maybe it's a constructor application | (Var fun, args) <- collectArgs expr = case isDataConWorkId_maybe fun of - Just con | args `lengthAtLeast` dataConRepArity con - -- Check saturated; might be > because the - -- arity excludes type args - -> Just (ConVal (DataAlt con) args) + Just con | args `lengthAtLeast` dataConRepArity con + -- Check saturated; might be > because the + -- arity excludes type args + -> Just (ConVal (DataAlt con) args) - _other | valArgCount args < idArity fun - -- Under-applied function - -> Just LambdaVal -- Partial application + _other | valArgCount args < idArity fun + -- Under-applied function + -> Just LambdaVal -- Partial application - _other -> Nothing + _other -> Nothing isValue _env _expr = Nothing @@ -1759,27 +1752,27 @@ samePat :: CallPat -> CallPat -> Bool samePat (vs1, as1) (vs2, as2) = all2 same as1 as2 where - same (Var v1) (Var v2) - | v1 `elem` vs1 = v2 `elem` vs2 - | v2 `elem` vs2 = False - | otherwise = v1 == v2 + same (Var v1) (Var v2) + | v1 `elem` vs1 = v2 `elem` vs2 + | v2 `elem` vs2 = False + | otherwise = v1 == v2 same (Lit l1) (Lit l2) = l1==l2 same (App f1 a1) (App f2 a2) = same f1 f2 && same a1 a2 - same (Type {}) (Type {}) = True -- Note [Ignore type differences] + same (Type {}) (Type {}) = True -- Note [Ignore type differences] same (Coercion {}) (Coercion {}) = True same (Tick _ e1) e2 = same e1 e2 -- Ignore casts and notes - same (Cast e1 _) e2 = same e1 e2 + same (Cast e1 _) e2 = same e1 e2 same e1 (Tick _ e2) = same e1 e2 same e1 (Cast e2 _) = same e1 e2 - same e1 e2 = WARN( bad e1 || bad e2, ppr e1 $$ ppr e2) - False -- Let, lambda, case should not occur + same e1 e2 = WARN( bad e1 || bad e2, ppr e1 $$ ppr e2) + False -- Let, lambda, case should not occur bad (Case {}) = True bad (Let {}) = True bad (Lam {}) = True - bad _other = False + bad _other = False \end{code} Note [Ignore type differences] @@ -1787,6 +1780,6 @@ Note [Ignore type differences] We do not want to generate specialisations where the call patterns differ only in their type arguments! Not only is it utterly useless, but it also means that (with polymorphic recursion) we can generate -an infinite number of specialisations. Example is Data.Sequence.adjustTree, +an infinite number of specialisations. Example is Data.Sequence.adjustTree, I think. |