#include "HsVersions.h"
import SimplEnv
+import CoreMonad ( SimplifierMode(..), Tick(..) )
import DynFlags
import StaticFlags
import CoreSyn
{- $$ nest 2 (pprSimplEnv se) -}) $$ ppr cont
ppr (StrictBind b _ _ _ cont) = (ptext (sLit "StrictBind") <+> ppr b) $$ ppr cont
ppr (StrictArg ai _ cont) = (ptext (sLit "StrictArg") <+> ppr (ai_fun ai)) $$ ppr cont
- ppr (Select dup bndr alts _ cont) = (ptext (sLit "Select") <+> ppr dup <+> ppr bndr) $$
- (nest 4 (ppr alts)) $$ ppr cont
+ ppr (Select dup bndr alts se cont) = (ptext (sLit "Select") <+> ppr dup <+> ppr bndr) $$
+ (nest 2 $ vcat [ppr (seTvSubst se), ppr alts]) $$ ppr cont
ppr (CoerceIt co cont) = (ptext (sLit "CoerceIt") <+> ppr co) $$ ppr cont
data DupFlag = OkToDup | NoDup
countArgs (ApplyTo _ _ _ cont) = 1 + countArgs cont
countArgs _ = 0
-contArgs :: SimplCont -> ([OutExpr], SimplCont)
+contArgs :: SimplCont -> (Bool, [ArgSummary], SimplCont)
-- Uses substitution to turn each arg into an OutExpr
-contArgs cont = go [] cont
+contArgs cont@(ApplyTo {})
+ = case go [] cont of { (args, cont') -> (False, args, cont') }
where
- go args (ApplyTo _ arg se cont) = go (substExpr se arg : args) cont
- go args cont = (reverse args, cont)
+ go args (ApplyTo _ arg se cont)
+ | isTypeArg arg = go args cont
+ | otherwise = go (is_interesting arg se : args) cont
+ go args cont = (reverse args, cont)
+
+ is_interesting arg se = interestingArg (substExpr (text "contArgs") se arg)
+ -- Do *not* use short-cutting substitution here
+ -- because we want to get as much IdInfo as possible
+
+contArgs cont = (True, [], cont)
pushArgs :: SimplEnv -> [CoreExpr] -> SimplCont -> SimplCont
pushArgs _env [] cont = cont
%* *
%************************************************************************
-\begin{code}
-simplEnvForGHCi :: SimplEnv
-simplEnvForGHCi = mkSimplEnv allOffSwitchChecker $
- SimplGently { sm_rules = False, sm_inline = False }
- -- Do not do any inlining, in case we expose some unboxed
- -- tuple stuff that confuses the bytecode interpreter
-
-simplEnvForRules :: SimplEnv
-simplEnvForRules = mkSimplEnv allOffSwitchChecker $
- SimplGently { sm_rules = True, sm_inline = False }
-
-updModeForInlineRules :: SimplifierMode -> SimplifierMode
-updModeForInlineRules mode
- = case mode of
- SimplGently {} -> mode -- Don't modify mode if we already gentle
- SimplPhase {} -> SimplGently { sm_rules = True, sm_inline = True }
- -- Simplify as much as possible, subject to the usual "gentle" rules
-\end{code}
-
Inlining is controlled partly by the SimplifierMode switch. This has two
settings
InlineRule, because then recursive knots in instance declarations
don't get unravelled.
-However, *sometimes* SimplGently must do no call-site inlining at all.
-Before full laziness we must be careful not to inline wrappers,
-because doing so inhibits floating
+However, *sometimes* SimplGently must do no call-site inlining at all
+(hence sm_inline = False). Before full laziness we must be careful
+not to inline wrappers, because doing so inhibits floating
e.g. ...(case f x of ...)...
==> ...(case (case x of I# x# -> fw x#) of ...)...
==> ...(case x of I# x# -> case fw x# of ...)...
to work in Template Haskell when simplifying
splices, so we get simpler code for literal strings
-Note [Simplifying gently inside InlineRules]
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-We don't do much simplification inside InlineRules (which come from
-INLINE pragmas). It really is important to switch off inlinings
-inside such expressions. Consider the following example
+But watch out: list fusion can prevent floating. So use phase control
+to switch off those rules until after floating.
+Note [Simplifying inside InlineRules]
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+We must take care with simplification inside InlineRules (which come from
+INLINE pragmas).
+
+First, consider the following example
let f = \pq -> BIG
in
let g = \y -> f y y
{-# INLINE g #-}
in ...g...g...g...g...g...
+Now, if that's the ONLY occurrence of f, it might be inlined inside g,
+and thence copied multiple times when g is inlined. HENCE we treat
+any occurrence in an InlineRule as a multiple occurrence, not a single
+one; see OccurAnal.addRuleUsage.
+
+Second, we do want *do* to some modest rules/inlining stuff in InlineRules,
+partly to eliminate senseless crap, and partly to break the recursive knots
+generated by instance declarations. To keep things simple, we always set
+the phase to 'gentle' when processing InlineRules. OK, so suppose we have
+ {-# INLINE <act> f #-}
+ f = <rhs>
+meaning "inline f in phases p where activation <act>(p) holds".
+Then what inlinings/rules can we apply to the copy of <rhs> captured in
+f's InlineRule? Our model is that literally <rhs> is substituted for
+f when it is inlined. So our conservative plan (implemented by
+updModeForInlineRules) is this:
+
+ -------------------------------------------------------------
+ When simplifying the RHS of an InlineRule,
+ If the InlineRule becomes active in phase p, then
+ if the current phase is *earlier than* p,
+ make no inlinings or rules active when simplifying the RHS
+ otherwise
+ set the phase to p when simplifying the RHS
+ -------------------------------------------------------------
+
+That ensures that
+
+ a) Rules/inlinings that *cease* being active before p will
+ not apply to the InlineRule rhs, consistent with it being
+ inlined in its *original* form in phase p.
+
+ b) Rules/inlinings that only become active *after* p will
+ not apply to the InlineRule rhs, again to be consistent with
+ inlining the *original* rhs in phase p.
+
+For example,
+ {-# INLINE f #-}
+ f x = ...g...
-Now, if that's the ONLY occurrence of f, it will be inlined inside g,
-and thence copied multiple times when g is inlined.
+ {-# NOINLINE [1] g #-}
+ g y = ...
-This function may be inlinined in other modules, so we don't want to
-remove (by inlining) calls to functions that have specialisations, or
-that may have transformation rules in an importing scope.
+ {-# RULE h g = ... #-}
+Here we must not inline g into f's RHS, even when we get to phase 0,
+because when f is later inlined into some other module we want the
+rule for h to fire.
-E.g. {-# INLINE f #-}
+Similarly, consider
+ {-# INLINE f #-}
f x = ...g...
-and suppose that g is strict *and* has specialisations. If we inline
-g's wrapper, we deny f the chance of getting the specialised version
-of g when f is inlined at some call site (perhaps in some other
-module).
+ g y = ...
+and suppose that there are auto-generated specialisations and a strictness
+wrapper for g. The specialisations get activation AlwaysActive, and the
+strictness wrapper get activation (ActiveAfter 0). So the strictness
+wrepper fails the test and won't be inlined into f's InlineRule. That
+means f can inline, expose the specialised call to g, so the specialisation
+rules can fire.
+A note about wrappers
+~~~~~~~~~~~~~~~~~~~~~
It's also important not to inline a worker back into a wrapper.
A wrapper looks like
wraper = inline_me (\x -> ...worker... )
the wrapper (initially, the worker's only call site!). But,
if the wrapper is sure to be called, the strictness analyser will
mark it 'demanded', so when the RHS is simplified, it'll get an ArgOf
-continuation. That's why the keep_inline predicate returns True for
-ArgOf continuations. It shouldn't do any harm not to dissolve the
-inline-me note under these circumstances.
+continuation.
-Although we do very little simplification inside an InlineRule,
-the RHS is simplified as normal. For example:
+\begin{code}
+simplEnvForGHCi :: SimplEnv
+simplEnvForGHCi = mkSimplEnv allOffSwitchChecker $
+ SimplGently { sm_rules = False, sm_inline = False }
+ -- Do not do any inlining, in case we expose some unboxed
+ -- tuple stuff that confuses the bytecode interpreter
+
+simplEnvForRules :: SimplEnv
+simplEnvForRules = mkSimplEnv allOffSwitchChecker $
+ SimplGently { sm_rules = True, sm_inline = False }
+
+updModeForInlineRules :: Activation -> SimplifierMode -> SimplifierMode
+-- See Note [Simplifying inside InlineRules]
+-- Treat Gentle as phase "infinity"
+-- If current_phase `earlier than` inline_rule_start_phase
+-- then no_op
+-- else
+-- if current_phase `same phase` inline_rule_start_phase
+-- then current_phase (keep gentle flags)
+-- else inline_rule_start_phase
+updModeForInlineRules inline_rule_act current_mode
+ = case inline_rule_act of
+ NeverActive -> no_op
+ AlwaysActive -> mk_gentle current_mode
+ ActiveBefore {} -> mk_gentle current_mode
+ ActiveAfter n -> mk_phase n current_mode
+ where
+ no_op = SimplGently { sm_rules = False, sm_inline = False }
- all xs = foldr (&&) True xs
- any p = all . map p {-# INLINE any #-}
+ mk_gentle (SimplGently {}) = current_mode
+ mk_gentle _ = SimplGently { sm_rules = True, sm_inline = True }
-The RHS of 'any' will get optimised and deforested; but the InlineRule
-will still mention the original RHS.
+ mk_phase n (SimplPhase _ ss) = SimplPhase n ss
+ mk_phase n (SimplGently {}) = SimplPhase n ["gentle-rules"]
+\end{code}
preInlineUnconditionally
However, as usual for Gentle mode, do not inline things that are
inactive in the intial stages. See Note [Gentle mode].
+Note [InlineRule and preInlineUnconditionally]
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+Surprisingly, do not pre-inline-unconditionally Ids with INLINE pragmas!
+Example
+
+ {-# INLINE f #-}
+ f :: Eq a => a -> a
+ f x = ...
+
+ fInt :: Int -> Int
+ fInt = f Int dEqInt
+
+ ...fInt...fInt...fInt...
+
+Here f occurs just once, in the RHS of f1. But if we inline it there
+we'll lose the opportunity to inline at each of fInt's call sites.
+The INLINE pragma will only inline when the application is saturated
+for exactly this reason; and we don't want PreInlineUnconditionally
+to second-guess it. A live example is Trac #3736.
+ c.f. Note [InlineRule and postInlineUnconditionally]
+
Note [Top-level botomming Ids]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Don't inline top-level Ids that are bottoming, even if they are used just
preInlineUnconditionally :: SimplEnv -> TopLevelFlag -> InId -> InExpr -> Bool
preInlineUnconditionally env top_lvl bndr rhs
| not active = False
+ | isStableUnfolding (idUnfolding bndr) = False -- Note [InlineRule and preInlineUnconditionally]
| isTopLevel top_lvl && isBottomingId bndr = False -- Note [Top-level bottoming Ids]
| opt_SimplNoPreInlining = False
| otherwise = case idOccInfo bndr of
and now postInlineUnconditionally, losing the InlineRule on f. Now f'
won't inline because 'e' is too big.
+ c.f. Note [InlineRule and preInlineUnconditionally]
+
%************************************************************************
%* *
mkLam _b [] body
= return body
-mkLam env bndrs body
+mkLam _env bndrs body
= do { dflags <- getDOptsSmpl
; mkLam' dflags bndrs body }
where
; return etad_lam }
| dopt Opt_DoLambdaEtaExpansion dflags,
- not (inGentleMode env), -- In gentle mode don't eta-expansion
- any isRuntimeVar bndrs -- because it can clutter up the code
- -- with casts etc that may not be removed
+ not (all isTyVar bndrs) -- Don't eta expand type abstractions
= do { let body' = tryEtaExpansion dflags body
; return (mkLams bndrs body') }
abstractFloats main_tvs body_env body
= ASSERT( notNull body_floats )
do { (subst, float_binds) <- mapAccumLM abstract empty_subst body_floats
- ; return (float_binds, CoreSubst.substExpr subst body) }
+ ; return (float_binds, CoreSubst.substExpr (text "abstract_floats1") subst body) }
where
main_tv_set = mkVarSet main_tvs
body_floats = getFloats body_env
subst' = CoreSubst.extendIdSubst subst id poly_app
; return (subst', (NonRec poly_id poly_rhs)) }
where
- rhs' = CoreSubst.substExpr subst rhs
+ rhs' = CoreSubst.substExpr (text "abstract_floats2") subst rhs
tvs_here | any isCoVar main_tvs = main_tvs -- Note [Abstract over coercions]
| otherwise
= varSetElems (main_tv_set `intersectVarSet` exprSomeFreeVars isTyVar rhs')
abstract subst (Rec prs)
= do { (poly_ids, poly_apps) <- mapAndUnzipM (mk_poly tvs_here) ids
; let subst' = CoreSubst.extendSubstList subst (ids `zip` poly_apps)
- poly_rhss = [mkLams tvs_here (CoreSubst.substExpr subst' rhs) | rhs <- rhss]
+ poly_rhss = [mkLams tvs_here (CoreSubst.substExpr (text "abstract_floats3") subst' rhs)
+ | rhs <- rhss]
; return (subst', Rec (poly_ids `zip` poly_rhss)) }
where
(ids,rhss) = unzip prs
projects / ghc-hetmet.git / blobdiff