\begin{code}
module WorkWrap ( wwTopBinds, mkWrapper ) where
-#include "HsVersions.h"
-
import CoreSyn
import CoreUnfold ( certainlyWillInline )
-import CoreUtils ( exprType, exprIsHNF, exprArity )
+import CoreUtils ( exprType, exprIsHNF, mkInlineMe )
+import CoreArity ( exprArity )
import Var
-import Id ( Id, idType, isOneShotLambda,
- setIdNewStrictness, mkWorkerId,
- setIdWorkerInfo, setInlinePragma,
- setIdArity, idInfo )
-import MkId ( lazyIdKey, lazyIdUnfolding )
+import Id
import Type ( Type )
import IdInfo
import NewDemand ( Demand(..), StrictSig(..), DmdType(..), DmdResult(..),
Demands(..), mkTopDmdType, isBotRes, returnsCPR, topSig, isAbsent
)
import UniqSupply
-import Unique ( hasKey )
-import BasicTypes ( RecFlag(..), isNonRec, isNeverActive )
+import BasicTypes ( RecFlag(..), isNonRec, isNeverActive,
+ Activation, inlinePragmaActivation )
import VarEnv ( isEmptyVarEnv )
import Maybes ( orElse )
import WwLib
import Util ( lengthIs, notNull )
import Outputable
import MonadUtils
+
+#include "HsVersions.h"
\end{code}
We take Core bindings whose binders have:
\begin{code}
wwExpr :: CoreExpr -> UniqSM CoreExpr
-wwExpr e@(Type _) = return e
-wwExpr e@(Lit _) = return e
+wwExpr e@(Type {}) = return e
+wwExpr e@(Lit {}) = return e
+wwExpr e@(Var {}) = return e
wwExpr e@(Note InlineMe _) = return e
-- Don't w/w inside InlineMe's
-wwExpr e@(Var v)
- | v `hasKey` lazyIdKey = return lazyIdUnfolding
- | otherwise = return e
- -- HACK alert: Inline 'lazy' after strictness analysis
- -- (but not inside InlineMe's)
-
wwExpr (Lam binder expr)
= Lam binder <$> wwExpr expr
The only reason this is monadised is for the unique supply.
-Note [Don't w/w inline things]
+Note [Don't w/w inline things (a)]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
It's very important to refrain from w/w-ing an INLINE function
If we do so by mistake we transform
in a recursive group. It might not be the loop breaker. (We could
test for loop-breaker-hood, but I'm not sure that ever matters.)
+Note [Don't w/w inline things (b)]
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+In general, therefore, we refrain from w/w-ing *small* functions,
+because they'll inline anyway. But we must take care: it may look
+small now, but get to be big later after other inling has happened.
+So we take the precaution of adding an INLINE pragma to any such
+functions.
+
+I made this change when I observed a big function at the end of
+compilation with a useful strictness signature but no w-w. When
+I measured it on nofib, it didn't make much difference; just a few
+percent improved allocation on one benchmark (bspt/Euclid.space).
+But nothing got worse.
+
+
\begin{code}
tryWW :: RecFlag
-> Id -- The fn binder
-- if two, then a worker and a
-- wrapper.
tryWW is_rec fn_id rhs
- | -- isNonRec is_rec && -- Now omitted: see Note [Don't w/w inline things]
- certainlyWillInline unfolding
-
- || isNeverActive inline_prag
+ | isNeverActive inline_act
-- No point in worker/wrappering if the thing is never inlined!
-- Because the no-inline prag will prevent the wrapper ever
-- being inlined at a call site.
- = return [ (new_fn_id, rhs) ]
+ --
+ -- Furthermore, don't even expose strictness info
+ = return [ (fn_id, rhs) ]
| is_thunk && worthSplittingThunk maybe_fn_dmd res_info
= ASSERT2( isNonRec is_rec, ppr new_fn_id ) -- The thunk must be non-recursive
+ checkSize new_fn_id rhs $
splitThunk new_fn_id rhs
| is_fun && worthSplittingFun wrap_dmds res_info
- = splitFun new_fn_id fn_info wrap_dmds res_info inline_prag rhs
+ = checkSize new_fn_id rhs $
+ splitFun new_fn_id fn_info wrap_dmds res_info inline_act rhs
| otherwise
= return [ (new_fn_id, rhs) ]
where
fn_info = idInfo fn_id
maybe_fn_dmd = newDemandInfo fn_info
- unfolding = unfoldingInfo fn_info
- inline_prag = inlinePragInfo fn_info
+ inline_act = inlinePragmaActivation (inlinePragInfo fn_info)
-- In practice it always will have a strictness
-- signature, even if it's a uninformative one
is_thunk = not is_fun && not (exprIsHNF rhs)
---------------------
-splitFun :: Id -> IdInfo -> [Demand] -> DmdResult -> InlinePragInfo -> Expr Var
+checkSize :: Id -> CoreExpr -> UniqSM [(Id,CoreExpr)] -> UniqSM [(Id,CoreExpr)]
+ -- See Note [Don't w/w inline things (a) and (b)]
+checkSize fn_id rhs thing_inside
+ | certainlyWillInline unfolding = return [ (fn_id, mkInlineMe rhs) ]
+ -- Note [Don't w/w inline things (b)]
+ | otherwise = thing_inside
+ where
+ unfolding = idUnfolding fn_id
+
+---------------------
+splitFun :: Id -> IdInfo -> [Demand] -> DmdResult -> Activation -> Expr Var
-> UniqSM [(Id, CoreExpr)]
-splitFun fn_id fn_info wrap_dmds res_info inline_prag rhs
+splitFun fn_id fn_info wrap_dmds res_info inline_act rhs
= WARN( not (wrap_dmds `lengthIs` arity), ppr fn_id <+> (ppr arity $$ ppr wrap_dmds $$ ppr res_info) )
(do {
-- The arity should match the signature
; let
work_rhs = work_fn rhs
work_id = mkWorkerId work_uniq fn_id (exprType work_rhs)
- `setInlinePragma` inline_prag
- -- Any inline pragma (which sets when inlining is active)
+ `setInlineActivation` inline_act
+ -- Any inline activation (which sets when inlining is active)
-- on the original function is duplicated on the worker and wrapper
-- It *matters* that the pragma stays on the wrapper
-- It seems sensible to have it on the worker too, although we
-- can't think of a compelling reason. (In ptic, INLINE things are
- -- not w/wd)
+ -- not w/wd). However, the RuleMatchInfo is not transferred since
+ -- it does not make sense for workers to be constructorlike.
`setIdNewStrictness` StrictSig (mkTopDmdType work_demands work_res_info)
-- Even though we may not be at top level,
-- it's ok to give it an empty DmdEnv
projects / ghc-hetmet.git / blobdiff