import Var ( Var, Id, setVarUnique )
import VarSet
import VarEnv
-import Id ( mkSysLocal, idType, idNewDemandInfo, idArity,
+import Id ( mkSysLocal, idType, idNewDemandInfo, idArity, setIdUnfolding, setIdType,
isFCallId, isGlobalId, isImplicitId,
isLocalId, hasNoBinding, idNewStrictness,
- idUnfolding, isDataConWorkId_maybe
+ idUnfolding, isDataConWorkId_maybe, isPrimOpId_maybe
)
+import DataCon ( isVanillaDataCon )
+import PrimOp ( PrimOp( DataToTagOp ) )
import HscTypes ( TypeEnv, typeEnvElts, TyThing( AnId ) )
import BasicTypes ( TopLevelFlag(..), isTopLevel, isNotTopLevel,
RecFlag(..), isNonRec
corePrepExpr dflags expr
= do showPass dflags "CorePrep"
us <- mkSplitUniqSupply 's'
- let new_expr = initUs_ us (corePrepAnExpr emptyVarEnv expr)
+ let new_expr = initUs_ us (corePrepAnExpr emptyCorePrepEnv expr)
dumpIfSet_dyn dflags Opt_D_dump_prep "CorePrep"
(ppr new_expr)
return new_expr
ppr (FloatLet bind) = text "FloatLet" <+> ppr bind
ppr (FloatCase b rhs spec) = text "FloatCase" <+> ppr b <+> ppr spec <+> equals <+> ppr rhs
-type CloneEnv = IdEnv Id -- Clone local Ids
-
deFloatTop :: Floats -> [CoreBind]
-- For top level only; we don't expect any FloatCases
deFloatTop (Floats _ floats)
allLazy :: TopLevelFlag -> RecFlag -> Floats -> Bool
allLazy top_lvl is_rec (Floats ok_to_spec _)
= case ok_to_spec of
- OkToSpec -> True
+ OkToSpec -> True
NotOkToSpec -> False
IfUnboxedOk -> isNotTopLevel top_lvl && isNonRec is_rec
corePrepTopBinds :: [CoreBind] -> UniqSM Floats
corePrepTopBinds binds
- = go emptyVarEnv binds
+ = go emptyCorePrepEnv binds
where
go env [] = returnUs emptyFloats
go env (bind : binds) = corePrepTopBind env bind `thenUs` \ (env', bind') ->
-- it looks difficult.
--------------------------------
-corePrepTopBind :: CloneEnv -> CoreBind -> UniqSM (CloneEnv, Floats)
+corePrepTopBind :: CorePrepEnv -> CoreBind -> UniqSM (CorePrepEnv, Floats)
corePrepTopBind env (NonRec bndr rhs)
= cloneBndr env bndr `thenUs` \ (env', bndr') ->
corePrepRhs TopLevel NonRecursive env (bndr, rhs) `thenUs` \ (floats, rhs') ->
corePrepTopBind env (Rec pairs) = corePrepRecPairs TopLevel env pairs
--------------------------------
-corePrepBind :: CloneEnv -> CoreBind -> UniqSM (CloneEnv, Floats)
+corePrepBind :: CorePrepEnv -> CoreBind -> UniqSM (CorePrepEnv, Floats)
-- This one is used for *local* bindings
corePrepBind env (NonRec bndr rhs)
= etaExpandRhs bndr rhs `thenUs` \ rhs1 ->
corePrepExprFloat env rhs1 `thenUs` \ (floats, rhs2) ->
- cloneBndr env bndr `thenUs` \ (env', bndr') ->
- mkLocalNonRec bndr' (bdrDem bndr') floats rhs2 `thenUs` \ floats' ->
- returnUs (env', floats')
+ cloneBndr env bndr `thenUs` \ (_, bndr') ->
+ mkLocalNonRec bndr' (bdrDem bndr) floats rhs2 `thenUs` \ (floats', bndr'') ->
+ -- We want bndr'' in the envt, because it records
+ -- the evaluated-ness of the binder
+ returnUs (extendCorePrepEnv env bndr bndr'', floats')
corePrepBind env (Rec pairs) = corePrepRecPairs NotTopLevel env pairs
--------------------------------
-corePrepRecPairs :: TopLevelFlag -> CloneEnv
+corePrepRecPairs :: TopLevelFlag -> CorePrepEnv
-> [(Id,CoreExpr)] -- Recursive bindings
- -> UniqSM (CloneEnv, Floats)
+ -> UniqSM (CorePrepEnv, Floats)
-- Used for all recursive bindings, top level and otherwise
corePrepRecPairs lvl env pairs
= cloneBndrs env (map fst pairs) `thenUs` \ (env', bndrs') ->
--------------------------------
corePrepRhs :: TopLevelFlag -> RecFlag
- -> CloneEnv -> (Id, CoreExpr)
+ -> CorePrepEnv -> (Id, CoreExpr)
-> UniqSM (Floats, CoreExpr)
-- Used for top-level bindings, and local recursive bindings
corePrepRhs top_lvl is_rec env (bndr, rhs)
-- ---------------------------------------------------------------------------
-- This is where we arrange that a non-trivial argument is let-bound
-corePrepArg :: CloneEnv -> CoreArg -> RhsDemand
+corePrepArg :: CorePrepEnv -> CoreArg -> RhsDemand
-> UniqSM (Floats, CoreArg)
corePrepArg env arg dem
= corePrepExprFloat env arg `thenUs` \ (floats, arg') ->
if exprIsTrivial arg'
then returnUs (floats, arg')
else newVar (exprType arg') `thenUs` \ v ->
- mkLocalNonRec v dem floats arg' `thenUs` \ floats' ->
- returnUs (floats', Var v)
+ mkLocalNonRec v dem floats arg' `thenUs` \ (floats', v') ->
+ returnUs (floats', Var v')
-- version that doesn't consider an scc annotation to be trivial.
exprIsTrivial (Var v) = True
-- Dealing with expressions
-- ---------------------------------------------------------------------------
-corePrepAnExpr :: CloneEnv -> CoreExpr -> UniqSM CoreExpr
+corePrepAnExpr :: CorePrepEnv -> CoreExpr -> UniqSM CoreExpr
corePrepAnExpr env expr
= corePrepExprFloat env expr `thenUs` \ (floats, expr) ->
mkBinds floats expr
-corePrepExprFloat :: CloneEnv -> CoreExpr -> UniqSM (Floats, CoreExpr)
+corePrepExprFloat :: CorePrepEnv -> CoreExpr -> UniqSM (Floats, CoreExpr)
-- If
-- e ===> (bs, e')
-- then
corePrepExprFloat env (Var v)
= fiddleCCall v `thenUs` \ v1 ->
- let v2 = lookupVarEnv env v1 `orElse` v1 in
- maybeSaturate v2 (Var v2) 0 (idType v2) `thenUs` \ app ->
- returnUs (emptyFloats, app)
+ let
+ v2 = lookupCorePrepEnv env v1
+ in
+ maybeSaturate v2 (Var v2) 0 emptyFloats (idType v2)
corePrepExprFloat env expr@(Type _)
= returnUs (emptyFloats, expr)
corePrepExprFloat env (Case scrut bndr ty alts)
= corePrepExprFloat env scrut `thenUs` \ (floats1, scrut1) ->
deLamFloat scrut1 `thenUs` \ (floats2, scrut2) ->
- cloneBndr env bndr `thenUs` \ (env', bndr') ->
+ let
+ bndr1 = bndr `setIdUnfolding` evaldUnfolding
+ -- Record that the case binder is evaluated in the alternatives
+ in
+ cloneBndr env bndr1 `thenUs` \ (env', bndr2) ->
mapUs (sat_alt env') alts `thenUs` \ alts' ->
- returnUs (floats1 `appendFloats` floats2 , Case scrut2 bndr' ty alts')
+ returnUs (floats1 `appendFloats` floats2 , Case scrut2 bndr2 ty alts')
where
sat_alt env (con, bs, rhs)
- = cloneBndrs env bs `thenUs` \ (env', bs') ->
- corePrepAnExpr env' rhs `thenUs` \ rhs1 ->
+ = let
+ env1 = setGadt env con
+ in
+ cloneBndrs env1 bs `thenUs` \ (env2, bs') ->
+ corePrepAnExpr env2 rhs `thenUs` \ rhs1 ->
deLam rhs1 `thenUs` \ rhs2 ->
returnUs (con, bs', rhs2)
-- Now deal with the function
case head of
- Var fn_id -> maybeSaturate fn_id app depth ty `thenUs` \ app' ->
- returnUs (floats, app')
-
+ Var fn_id -> maybeSaturate fn_id app depth floats ty
_other -> returnUs (floats, app)
where
collect_args (Var v) depth
= fiddleCCall v `thenUs` \ v1 ->
- let v2 = lookupVarEnv env v1 `orElse` v1 in
+ let
+ v2 = lookupCorePrepEnv env v1
+ in
returnUs (Var v2, (Var v2, depth), idType v2, emptyFloats, stricts)
where
stricts = case idNewStrictness v of
= collect_args fun depth `thenUs` \ (fun', hd, fun_ty, floats, ss) ->
returnUs (Note note fun', hd, fun_ty, floats, ss)
- -- non-variable fun, better let-bind it
+ -- N-variable fun, better let-bind it
-- ToDo: perhaps we can case-bind rather than let-bind this closure,
-- since it is sure to be evaluated.
collect_args fun depth
= corePrepExprFloat env fun `thenUs` \ (fun_floats, fun') ->
newVar ty `thenUs` \ fn_id ->
- mkLocalNonRec fn_id onceDem fun_floats fun' `thenUs` \ floats ->
- returnUs (Var fn_id, (Var fn_id, depth), ty, floats, [])
+ mkLocalNonRec fn_id onceDem fun_floats fun' `thenUs` \ (floats, fn_id') ->
+ returnUs (Var fn_id', (Var fn_id', depth), ty, floats, [])
where
ty = exprType fun
-- maybeSaturate deals with saturating primops and constructors
-- The type is the type of the entire application
-maybeSaturate :: Id -> CoreExpr -> Int -> Type -> UniqSM CoreExpr
-maybeSaturate fn expr n_args ty
+maybeSaturate :: Id -> CoreExpr -> Int -> Floats -> Type -> UniqSM (Floats, CoreExpr)
+maybeSaturate fn expr n_args floats ty
| hasNoBinding fn = saturate_it
- | otherwise = returnUs expr
+ | otherwise = returnUs (floats, expr)
where
fn_arity = idArity fn
excess_arity = fn_arity - n_args
- saturate_it = getUniquesUs `thenUs` \ us ->
- returnUs (etaExpand excess_arity us expr ty)
+ saturate_it = getUniquesUs `thenUs` \ us ->
+ let expr' = etaExpand excess_arity us expr ty in
+ case isPrimOpId_maybe fn of
+ Just DataToTagOp -> hack_data2tag expr'
+ other -> returnUs (floats, expr')
+
+ -- Ensure that the argument of DataToTagOp is evaluated
+ hack_data2tag app@(Var _fn `App` _ty `App` Var arg_id)
+ | isEvaldUnfolding (idUnfolding arg_id) -- Includes nullary constructors
+ = returnUs (floats, app) -- The arg is evaluated
+ hack_data2tag app@(Var fn `App` Type ty `App` arg)
+ | otherwise -- Arg not evaluated, so evaluate it
+ = newVar ty `thenUs` \ arg_id1 ->
+ let arg_id2 = setIdUnfolding arg_id1 evaldUnfolding
+ new_float = FloatCase arg_id2 arg False
+ in
+ returnUs (addFloat floats new_float,
+ Var fn `App` Type ty `App` Var arg_id2)
+
-- ---------------------------------------------------------------------------
-- Precipitating the floating bindings
-- v = f (x `divInt#` y)
-- we don't want to float the case, even if f has arity 2,
-- because floating the case would make it evaluated too early
- --
- -- Finally, eta-expand the RHS, for the benefit of the code gen
returnUs (floats, rhs)
| otherwise
-- mkLocalNonRec is used only for *nested*, *non-recursive* bindings
mkLocalNonRec :: Id -> RhsDemand -- Lhs: id with demand
-> Floats -> CoreExpr -- Rhs: let binds in body
- -> UniqSM Floats
+ -> UniqSM (Floats, Id) -- The new Id may have an evaldUnfolding,
+ -- to record that it's been evaluated
mkLocalNonRec bndr dem floats rhs
| isUnLiftedType (idType bndr)
let
float = FloatCase bndr rhs (exprOkForSpeculation rhs)
in
- returnUs (addFloat floats float)
+ returnUs (addFloat floats float, evald_bndr)
| isStrict dem
-- It's a strict let so we definitely float all the bindings
float | exprIsValue rhs = FloatLet (NonRec bndr rhs)
| otherwise = FloatCase bndr rhs (exprOkForSpeculation rhs)
in
- returnUs (addFloat floats float)
+ returnUs (addFloat floats float, evald_bndr)
| otherwise
= floatRhs NotTopLevel NonRecursive bndr (floats, rhs) `thenUs` \ (floats', rhs') ->
- returnUs (addFloat floats' (FloatLet (NonRec bndr rhs')))
+ returnUs (addFloat floats' (FloatLet (NonRec bndr rhs')),
+ if exprIsValue rhs' then evald_bndr else bndr)
+
+ where
+ evald_bndr = bndr `setIdUnfolding` evaldUnfolding
+ -- Record if the binder is evaluated
mkBinds :: Floats -> CoreExpr -> UniqSM CoreExpr
%************************************************************************
\begin{code}
+-- ---------------------------------------------------------------------------
+-- The environment
+-- ---------------------------------------------------------------------------
+
+data CorePrepEnv = CPE (IdEnv Id) -- Clone local Ids
+ Bool -- True <=> inside a GADT case; see Note [GADT]
+
+-- Note [GADT]
+--
+-- Be careful with cloning inside GADTs. For example,
+-- /\a. \f::a. \x::T a. case x of { T -> f True; ... }
+-- The case on x may refine the type of f to be a function type.
+-- Without this type refinement, exprType (f True) may simply fail,
+-- which is bad.
+--
+-- Solution: remember when we are inside a potentially-type-refining case,
+-- and in that situation use the type from the old occurrence
+-- when looking up occurrences
+
+emptyCorePrepEnv :: CorePrepEnv
+emptyCorePrepEnv = CPE emptyVarEnv False
+
+extendCorePrepEnv :: CorePrepEnv -> Id -> Id -> CorePrepEnv
+extendCorePrepEnv (CPE env gadt) id id' = CPE (extendVarEnv env id id') gadt
+
+lookupCorePrepEnv :: CorePrepEnv -> Id -> Id
+-- See Note [GADT] above
+lookupCorePrepEnv (CPE env gadt) id
+ = case lookupVarEnv env id of
+ Nothing -> id
+ Just id' | gadt -> setIdType id' (idType id)
+ | otherwise -> id'
+
+setGadt :: CorePrepEnv -> AltCon -> CorePrepEnv
+setGadt env@(CPE id_env _) (DataAlt data_con) | not (isVanillaDataCon data_con) = CPE id_env True
+setGadt env other = env
+
+
------------------------------------------------------------------------------
-- Cloning binders
-- ---------------------------------------------------------------------------
-cloneBndrs :: CloneEnv -> [Var] -> UniqSM (CloneEnv, [Var])
+cloneBndrs :: CorePrepEnv -> [Var] -> UniqSM (CorePrepEnv, [Var])
cloneBndrs env bs = mapAccumLUs cloneBndr env bs
-cloneBndr :: CloneEnv -> Var -> UniqSM (CloneEnv, Var)
+cloneBndr :: CorePrepEnv -> Var -> UniqSM (CorePrepEnv, Var)
cloneBndr env bndr
| isLocalId bndr
= getUniqueUs `thenUs` \ uniq ->
let
bndr' = setVarUnique bndr uniq
in
- returnUs (extendVarEnv env bndr bndr', bndr')
+ returnUs (extendCorePrepEnv env bndr bndr', bndr')
| otherwise -- Top level things, which we don't want
-- to clone, have become GlobalIds by now
projects / ghc-hetmet.git / blobdiff