X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=compiler%2FsimplCore%2FSimplUtils.lhs;h=56b07c480481a5b3f15d47cd52b577da3eafe843;hb=a263737bbf44050a7b5ecbe267ddf85d410b73e5;hp=663f543b2ca8d8b3e67ed1da28238db5cb82af56;hpb=1e50fd4185479a62e02d987bdfcb1c62712859ca;p=ghc-hetmet.git diff --git a/compiler/simplCore/SimplUtils.lhs b/compiler/simplCore/SimplUtils.lhs index 663f543..56b07c4 100644 --- a/compiler/simplCore/SimplUtils.lhs +++ b/compiler/simplCore/SimplUtils.lhs @@ -10,14 +10,14 @@ module SimplUtils ( -- Inlining, preInlineUnconditionally, postInlineUnconditionally, - activeInline, activeRule, inlineMode, + activeInline, activeRule, -- The continuation type SimplCont(..), DupFlag(..), ArgInfo(..), contIsDupable, contResultType, contIsTrivial, contArgs, dropArgs, - countValArgs, countArgs, splitInlineCont, + countValArgs, countArgs, mkBoringStop, mkLazyArgStop, contIsRhsOrArg, - interestingCallContext, interestingArgContext, + interestingCallContext, interestingArg, mkArgInfo, @@ -215,34 +215,6 @@ dropArgs :: Int -> SimplCont -> SimplCont dropArgs 0 cont = cont dropArgs n (ApplyTo _ _ _ cont) = dropArgs (n-1) cont dropArgs n other = pprPanic "dropArgs" (ppr n <+> ppr other) - --------------------- -splitInlineCont :: SimplCont -> Maybe (SimplCont, SimplCont) --- Returns Nothing if the continuation should dissolve an InlineMe Note --- Return Just (c1,c2) otherwise, --- where c1 is the continuation to put inside the InlineMe --- and c2 outside - --- Example: (__inline_me__ (/\a. e)) ty --- Here we want to do the beta-redex without dissolving the InlineMe --- See test simpl017 (and Trac #1627) for a good example of why this is important - -splitInlineCont (ApplyTo dup (Type ty) se c) - | Just (c1, c2) <- splitInlineCont c = Just (ApplyTo dup (Type ty) se c1, c2) -splitInlineCont cont@(Stop {}) = Just (mkBoringStop, cont) -splitInlineCont cont@(StrictBind {}) = Just (mkBoringStop, cont) -splitInlineCont _ = Nothing - -- NB: we dissolve an InlineMe in any strict context, - -- not just function aplication. - -- E.g. foldr k z (__inline_me (case x of p -> build ...)) - -- Here we want to get rid of the __inline_me__ so we - -- can float the case, and see foldr/build - -- - -- However *not* in a strict RHS, else we get - -- let f = __inline_me__ (\x. e) in ...f... - -- Now if f is guaranteed to be called, hence a strict binding - -- we don't thereby want to dissolve the __inline_me__; for - -- example, 'f' might be a wrapper, so we'd inline the worker \end{code} @@ -320,24 +292,25 @@ interestingCallContext cont ------------------- mkArgInfo :: Id + -> [CoreRule] -- Rules for function -> Int -- Number of value args -> SimplCont -- Context of the call -> ArgInfo -mkArgInfo fun n_val_args call_cont +mkArgInfo fun rules n_val_args call_cont | n_val_args < idArity fun -- Note [Unsaturated functions] = ArgInfo { ai_rules = False , ai_strs = vanilla_stricts , ai_discs = vanilla_discounts } | otherwise - = ArgInfo { ai_rules = interestingArgContext fun call_cont + = ArgInfo { ai_rules = interestingArgContext rules call_cont , ai_strs = add_type_str (idType fun) arg_stricts , ai_discs = arg_discounts } where vanilla_discounts, arg_discounts :: [Int] vanilla_discounts = repeat 0 arg_discounts = case idUnfolding fun of - CoreUnfolding _ _ _ _ _ (UnfoldIfGoodArgs _ discounts _ _) + CoreUnfolding {uf_guidance = UnfoldIfGoodArgs {ug_args = discounts}} -> discounts ++ vanilla_discounts _ -> vanilla_discounts @@ -391,7 +364,7 @@ it'll just be floated out again. Even if f has lots of discounts on its first argument -- it must be saturated for these to kick in -} -interestingArgContext :: Id -> SimplCont -> Bool +interestingArgContext :: [CoreRule] -> SimplCont -> Bool -- If the argument has form (f x y), where x,y are boring, -- and f is marked INLINE, then we don't want to inline f. -- But if the context of the argument is @@ -402,16 +375,18 @@ interestingArgContext :: Id -> SimplCont -> Bool -- where h has rules, then we do want to inline f; hence the -- call_cont argument to interestingArgContext -- --- The interesting_arg_ctxt flag makes this happen; if it's +-- The ai-rules flag makes this happen; if it's -- set, the inliner gets just enough keener to inline f -- regardless of how boring f's arguments are, if it's marked INLINE -- -- The alternative would be to *always* inline an INLINE function, -- regardless of how boring its context is; but that seems overkill -- For example, it'd mean that wrapper functions were always inlined -interestingArgContext fn call_cont - = idHasRules fn || go call_cont +interestingArgContext rules call_cont + = notNull rules || enclosing_fn_has_rules where + enclosing_fn_has_rules = go call_cont + go (Select {}) = False go (ApplyTo {}) = False go (StrictArg _ cci _ _) = interesting cci @@ -435,7 +410,7 @@ Inlining is controlled partly by the SimplifierMode switch. This has two settings: SimplGently (a) Simplifying before specialiser/full laziness - (b) Simplifiying inside INLINE pragma + (b) Simplifiying inside InlineRules (c) Simplifying the LHS of a rule (d) Simplifying a GHCi expression or Template Haskell splice @@ -456,17 +431,11 @@ running it, we don't want to use -O2. Indeed, we don't want to inline anything, because the byte-code interpreter might get confused about unboxed tuples and suchlike. -INLINE pragmas -~~~~~~~~~~~~~~ -SimplGently is also used as the mode to simplify inside an InlineMe note. - -\begin{code} -inlineMode :: SimplifierMode -inlineMode = SimplGently -\end{code} - -It really is important to switch off inlinings inside such -expressions. Consider the following example +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 let f = \pq -> BIG in @@ -475,16 +444,14 @@ expressions. Consider the following example in ...g...g...g...g...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. +and thence copied multiple times when g is inlined. - -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. +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. E.g. {-# INLINE f #-} - f x = ...g... + 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 @@ -502,15 +469,14 @@ 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. -Note that the result is that we do very little simplification -inside an InlineMe. +Although we do very little simplification inside an InlineRule, +the RHS is simplified as normal. For example: all xs = foldr (&&) True xs any p = all . map p {-# INLINE any #-} -Problem: any won't get deforested, and so if it's exported and the -importer doesn't use the inlining, (eg passes it as an arg) then we -won't get deforestation at all. We havn't solved this problem yet! +The RHS of 'any' will get optimised and deforested; but the InlineRule +will still mention the original RHS. preInlineUnconditionally @@ -589,7 +555,7 @@ preInlineUnconditionally env top_lvl bndr rhs where phase = getMode env active = case phase of - SimplGently -> isAlwaysActive act + SimplGently -> isEarlyActive act SimplPhase n _ -> isActive n act act = idInlineActivation bndr @@ -674,7 +640,7 @@ story for now. \begin{code} postInlineUnconditionally :: SimplEnv -> TopLevelFlag - -> InId -- The binder (an OutId would be fine too) + -> OutId -- The binder (an InId would be fine too) -> OccInfo -- From the InId -> OutExpr -> Unfolding @@ -684,6 +650,7 @@ postInlineUnconditionally env top_lvl bndr occ_info rhs unfolding | isLoopBreaker occ_info = False -- If it's a loop-breaker of any kind, don't inline -- because it might be referred to "earlier" | isExportedId bndr = False + | isInlineRule unfolding = False -- Note [InlineRule and postInlineUnconditionally] | exprIsTrivial rhs = True | otherwise = case occ_info of @@ -788,6 +755,23 @@ activeRule dflags env SimplPhase n _ -> Just (isActive n) \end{code} +Note [InlineRule and postInlineUnconditionally] +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +Do not do postInlineUnconditionally if the Id has an InlineRule, otherwise +we lose the unfolding. Example + + -- f has InlineRule with rhs (e |> co) + -- where 'e' is big + f = e |> co + +Then there's a danger we'll optimise to + + f' = e + f = f' |> co + +and now postInlineUnconditionally, losing the InlineRule on f. Now f' +won't inline because 'e' is too big. + %************************************************************************ %* * @@ -803,7 +787,7 @@ mkLam :: SimplEnv -> [OutBndr] -> OutExpr -> SimplM OutExpr mkLam _b [] body = return body -mkLam _env bndrs body +mkLam env bndrs body = do { dflags <- getDOptsSmpl ; mkLam' dflags bndrs body } where @@ -824,7 +808,9 @@ mkLam _env bndrs body ; return etad_lam } | dopt Opt_DoLambdaEtaExpansion dflags, - any isRuntimeVar bndrs + 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 = do { let body' = tryEtaExpansion dflags body ; return (mkLams bndrs body') }