import CoreLint ( showPass, endPass )
import CoreUtils ( exprType, mkPiTypes )
import CoreFVs ( exprsFreeVars )
-import CoreSubst ( Subst, mkSubst, substExpr )
import CoreTidy ( tidyRules )
import PprCore ( pprRules )
import WwLib ( mkWorkerArgs )
-import DataCon ( dataConRepArity, isVanillaDataCon, dataConTyVars )
-import Type ( Type, tyConAppArgs, tyVarsOfTypes )
+import DataCon ( dataConRepArity, dataConUnivTyVars )
+import Type ( Type, tyConAppArgs )
+import Coercion ( coercionKind )
import Rules ( matchN )
-import Unify ( coreRefineTys )
import Id ( Id, idName, idType, isDataConWorkId_maybe,
mkUserLocal, mkSysLocal, idUnfolding, isLocalId )
import Var ( Var )
Looks cool, but probably rare...but it might be easy to implement.
+
+Note [SpecConstr for casts]
+~~~~~~~~~~~~~~~~~~~~~~~~~~~
+Consider
+ data family T a :: *
+ data instance T Int = T Int
+
+ foo n = ...
+ where
+ go (T 0) = 0
+ go (T n) = go (T (n-1))
+
+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
+
+
-----------------------------------------------------
Stuff not yet handled
-----------------------------------------------------
instance Outputable ConValue where
ppr (CV con args) = ppr con <+> interpp'SP args
-refineConstrEnv :: Subst -> ConstrEnv -> ConstrEnv
--- The substitution is a type substitution only
-refineConstrEnv subst env = mapVarEnv refine_con_value env
- where
- refine_con_value (CV con args) = CV con (map (substExpr subst) args)
-
emptyScEnv = SCE { scope = emptyVarEnv, cons = emptyVarEnv }
data HowBound = RecFun -- These are the recursive functions for which
[(b,how_bound) | b <- case_bndr:alt_bndrs] }
-- Record RecArg for the components iff the scrutinee is RecArg
+ -- I think the only reason for this is to keep the usage envt small
+ -- so is it worth it at all?
-- [This comment looks plain wrong to me, so I'm ignoring it
-- "Also forget if the scrutinee is a RecArg, because we're
-- now in the branch of a case, and we don't want to
-- record a non-scrutinee use of v if we have
-- case v of { (a,b) -> ...(f v)... }" ]
- how_bound = case scrut of
- Var v -> lookupVarEnv cur_scope v `orElse` Other
- other -> Other
-
- extend_data_con data_con
- | isVanillaDataCon data_con = extendCons env1 scrut case_bndr (CV con vanilla_args)
- | otherwise = extendCons env2 scrut case_bndr (CV con gadt_args)
- -- Note env2 for GADTs
+ how_bound = get_how scrut
where
-
- vanilla_args = map Type (tyConAppArgs (idType case_bndr)) ++
- map varToCoreExpr alt_bndrs
-
- gadt_args = map (substExpr subst . varToCoreExpr) alt_bndrs
- -- This call generates some bogus warnings from substExpr,
- -- because it's inconvenient to put all the Ids in scope
- -- Will be fixed when we move to FC
-
- (alt_tvs, _) = span isTyVar alt_bndrs
- Just (tv_subst, is_local) = coreRefineTys data_con alt_tvs (idType case_bndr)
- subst = mkSubst in_scope tv_subst emptyVarEnv -- No Id substitition
- in_scope = mkInScopeSet (tyVarsOfTypes (varEnvElts tv_subst))
-
- env2 | is_local = env1
- | otherwise = env1 { cons = refineConstrEnv subst (cons env) }
+ get_how (Var v) = lookupVarEnv cur_scope v `orElse` Other
+ get_how (Cast e _) = get_how e
+ get_how (Note _ e) = get_how e
+ get_how other = Other
+ extend_data_con data_con =
+ extendCons env1 scrut case_bndr (CV con vanilla_args)
+ where
+ vanilla_args = map Type (tyConAppArgs (idType case_bndr)) ++
+ varsToCoreExprs alt_bndrs
extendCons :: ScEnv -> CoreExpr -> Id -> ConValue -> ScEnv
extendCons env scrut case_bndr val
{- Note [ScrutOcc]
-An occurrence of ScrutOcc indicates that the thing is *only* taken apart or applied.
+An occurrence of ScrutOcc indicates that the thing, or a `cast` version of the thing,
+is *only* taken apart or applied.
- Functions, litersl: ScrutOcc emptyUFM
+ Functions, literal: ScrutOcc emptyUFM
Data constructors: ScrutOcc subs,
where (subs :: UniqFM [ArgOcc]) gives usage of the *pattern-bound* components,
-}
instance Outputable ArgOcc where
- ppr (ScrutOcc xs) = ptext SLIT("scrut-occ") <> parens (ppr xs)
+ ppr (ScrutOcc xs) = ptext SLIT("scrut-occ") <> ppr xs
ppr UnkOcc = ptext SLIT("unk-occ")
ppr BothOcc = ptext SLIT("both-occ")
ppr NoOcc = ptext SLIT("no-occ")
conArgOccs (ScrutOcc fm) (DataAlt dc)
| Just pat_arg_occs <- lookupUFM fm dc
- = tyvar_unks ++ pat_arg_occs
- where
- tyvar_unks | isVanillaDataCon dc = [UnkOcc | tv <- dataConTyVars dc]
- | otherwise = []
+ = [UnkOcc | tv <- dataConUnivTyVars dc] ++ pat_arg_occs
conArgOccs other con = repeat UnkOcc
\end{code}
scExpr env e@(Var v) = returnUs (varUsage env v UnkOcc, e)
scExpr env (Note n e) = scExpr env e `thenUs` \ (usg,e') ->
returnUs (usg, Note n e')
+scExpr env (Cast e co)= scExpr env e `thenUs` \ (usg,e') ->
+ returnUs (usg, Cast e' co)
scExpr env (Lam b e) = scExpr (extendBndr env b) e `thenUs` \ (usg,e') ->
returnUs (usg, Lam b e')
----------------------
scScrut :: ScEnv -> CoreExpr -> ArgOcc -> UniqSM (ScUsage, CoreExpr)
-- Used for the scrutinee of a case,
--- or the function of an application
-scScrut env e@(Var v) occ = returnUs (varUsage env v occ, e)
-scScrut env e occ = scExpr env e
+-- or the function of an application.
+-- Remember to look through casts
+scScrut env e@(Var v) occ = returnUs (varUsage env v occ, e)
+scScrut env (Cast e co) occ = do { (usg, e') <- scScrut env e occ
+ ; returnUs (usg, Cast e' co) }
+scScrut env e occ = scExpr env e
----------------------
specialise env fn bndrs body body_usg
= do { let (_, bndr_occs) = lookupOccs body_usg bndrs
- ; mb_calls <- mapM (callToPats (scope env) bndr_occs)
+ ; mb_calls <- -- pprTrace "specialise" (ppr fn <+> ppr bndrs <+> ppr bndr_occs) $
+ mapM (callToPats (scope env) bndr_occs)
(lookupVarEnv (calls body_usg) fn `orElse` [])
; let good_calls :: [([Var], [CoreArg])]
[ exprsFreeVars pats `delVarSetList` vs
| (vs,pats) <- good_calls ]
uniq_calls = nubBy (same_call in_scope) good_calls
- in
- mapAndUnzipUs (spec_one env fn (mkLams bndrs body))
- (uniq_calls `zip` [1..]) }
+ ; mapAndUnzipUs (spec_one env fn (mkLams bndrs body))
+ (uniq_calls `zip` [1..]) }
where
-- Two calls are the same if they match both ways
same_call in_scope (vs1,as1)(vs2,as2)
-- Quantify over variables that are not in sccpe
-- See Note [Shadowing] at the top
- ; if or good_pats
+ ; -- pprTrace "callToPats" (ppr args $$ ppr prs $$ ppr bndr_occs) $
+ if or good_pats
then return (Just (qvars, pats))
else return Nothing }
then return (True, Var v)
else wildCardPat (idType v)
+argToPat in_scope con_env (Let _ arg) arg_occ
+ = argToPat in_scope con_env arg arg_occ
+ -- Look through let expressions
+ -- e.g. f (let v = rhs in \y -> ...v...)
+ -- Here we can specialise for f (\y -> ...)
+ -- because the rule-matcher will look through the let.
+
+argToPat in_scope con_env (Cast arg co) arg_occ
+ = do { (interesting, arg') <- argToPat in_scope con_env arg arg_occ
+ ; if interesting then
+ return (interesting, Cast arg' co)
+ else
+ wildCardPat (snd (coercionKind co)) }
+
argToPat in_scope con_env arg arg_occ
| is_value_lam arg
= return (True, arg)
mk_con_app :: AltCon -> [CoreArg] -> CoreExpr
mk_con_app (LitAlt lit) [] = Lit lit
mk_con_app (DataAlt con) args = mkConApp con args
+mk_con_app other args = panic "SpecConstr.mk_con_app"
\end{code}
projects / ghc-hetmet.git / blobdiff