% (c) The AQUA Project, Glasgow University, 1993-1996
%
\section[SimplVar]{Simplifier stuff related to variables}
-
+
\begin{code}
-#include "HsVersions.h"
-
module SimplVar (
- completeVar
+ completeVar,
+ simplBinder, simplBinders, simplTyBinder, simplTyBinders
) where
-IMP_Ubiq(){-uitous-}
-IMPORT_DELOOPER(SmplLoop) ( simplExpr )
+#include "HsVersions.h"
+
+import {-# SOURCE #-} Simplify ( simplExpr )
-import Constants ( uNFOLDING_USE_THRESHOLD,
- uNFOLDING_CON_DISCOUNT_WEIGHT
- )
import CmdLineOpts ( switchIsOn, SimplifierSwitch(..) )
import CoreSyn
-import CoreUnfold ( Unfolding(..), UfExpr, RdrName, UnfoldingGuidance(..), SimpleUnfolding(..),
- FormSummary,
- okToInline, smallEnoughToInline )
-import BinderInfo ( BinderInfo, noBinderInfo )
-
-import CostCentre ( CostCentre, noCostCentreAttached )
-import Id ( idType, getIdInfo, getIdUnfolding, getIdSpecialisation,
- idMustBeINLINEd, GenId{-instance Outputable-}
+import CoreUnfold ( Unfolding(..), UnfoldingGuidance(..),
+ SimpleUnfolding(..),
+ FormSummary, whnfOrBottom,
+ smallEnoughToInline )
+import Specialise ( substSpecEnvRhs )
+import BinderInfo ( BinderInfo, noBinderInfo, okToInline )
+
+import CostCentre ( CostCentre, isCurrentCostCentre )
+import Id ( idType, getIdInfo, getIdUnfolding,
+ getIdSpecialisation, setIdSpecialisation,
+ idMustBeINLINEd, idHasNoFreeTyVars,
+ mkIdWithNewUniq, mkIdWithNewType,
+ elemIdEnv, isNullIdEnv, addOneToIdEnv
)
-import SpecEnv ( SpecEnv, lookupSpecEnv )
-import IdInfo ( DeforestInfo(..) )
+import SpecEnv ( lookupSpecEnv, substSpecEnv, isEmptySpecEnv )
+import OccurAnal ( occurAnalyseGlobalExpr )
import Literal ( isNoRepLit )
import MagicUFs ( applyMagicUnfoldingFun, MagicUnfoldingFun )
-import PprStyle ( PprStyle(..) )
-import PprType ( GenType{-instance Outputable-} )
-import Pretty ( ppBesides, ppStr )
import SimplEnv
import SimplMonad
+import Type ( instantiateTy, mkTyVarTy )
import TyCon ( tyConFamilySize )
-import Util ( pprTrace, assertPanic, panic )
+import TyVar ( TyVar, cloneTyVar,
+ isEmptyTyVarEnv, addToTyVarEnv,
+ addOneToTyVarSet, elementOfTyVarSet
+ )
import Maybes ( maybeToBool )
+import Outputable
\end{code}
%************************************************************************
This where all the heavy-duty unfolding stuff comes into its own.
\begin{code}
-completeVar env var args
+completeVar env var args result_ty
| maybeToBool maybe_magic_result
= tick MagicUnfold `thenSmpl_`
magic_result
- | not do_deforest &&
- maybeToBool maybe_unfolding_info &&
- (not essential_unfoldings_only || idMustBeINLINEd var) &&
- ok_to_inline &&
- -- If "essential_unfolds_only" is true we do no inlinings at all,
+ -- Look for existing specialisations before
+ -- trying inlining
+ | maybeToBool maybe_specialisation
+ = tick SpecialisationDone `thenSmpl_`
+ simplExpr (bindTyVars env spec_bindings)
+ (occurAnalyseGlobalExpr spec_template)
+ remaining_args
+ result_ty
+
+
+ -- Look for an unfolding. There's a binding for the
+ -- thing, but perhaps we want to inline it anyway
+ | ( maybeToBool maybe_unfolding_info
+ && (not essential_unfoldings_only || idMustBeINLINEd var)
+ -- If "essential_unfoldings_only" is true we do no inlinings at all,
-- EXCEPT for things that absolutely have to be done
-- (see comments with idMustBeINLINEd)
- --
- -- Need to be careful: the RHS of INLINE functions is protected against inlining
- -- by essential_unfoldings_only being set true; we must not inline workers back into
- -- wrappers, even thouth the former have an unfold-always guidance.
- costCentreOk (getEnclosingCC env) (getEnclosingCC unfold_env)
- = tick UnfoldingDone `thenSmpl_`
-#ifdef DEBUG
- simplCount `thenSmpl` \ n ->
- (if n > 3000 then
- pprTrace "Ticks > 3000 and unfolding" (ppr PprDebug var)
- else
- id
+ && ok_to_inline
+ && costCentreOk (getEnclosingCC env) (getEnclosingCC unf_env)
)
-#endif
- simplExpr unfold_env unf_template args
+ = -- pprTrace "Unfolding" (ppr var) $
+ unfold var unf_env unf_template args result_ty
- | maybeToBool maybe_specialisation
- = tick SpecialisationDone `thenSmpl_`
- simplExpr (extendTyEnvList env spec_bindings)
- spec_template
- (map TyArg leftover_ty_args ++ remaining_args)
| otherwise
- = returnSmpl (mkGenApp (Var var) args)
+ = returnSmpl (mkGenApp (Var var') args)
where
+ info_from_env = lookupOutIdEnv env var
+ var' = case info_from_env of
+ Just (var', _, _) -> var'
+ Nothing -> var
+
unfolding_from_id = getIdUnfolding var
---------- Magic unfolding stuff
MagicUnfolding _ magic_fn -> applyMagicUnfoldingFun magic_fn
env args
other -> Nothing
- (Just magic_result) = maybe_magic_result
+ Just magic_result = maybe_magic_result
- ---------- Unfolding stuff
maybe_unfolding_info
- = case (lookupOutIdEnv env var, unfolding_from_id) of
+ = case (info_from_env, unfolding_from_id) of
(Just (_, occ_info, OutUnfolding enc_cc unf), _)
-> Just (occ_info, setEnclosingCC env enc_cc, unf)
- (Just (_, occ_info, InUnfolding env_unf unf), _)
- -> Just (occ_info, env_unf, unf)
--- This combineSimplEnv is WRONG. InUnfoldings are used for
--- recursive decls, and we're relying on using the old unfold enf
--- to avoid getting outselves in a loop!
--- -> Just (occ_info, combineSimplEnv env env_unf, unf)
-
(_, CoreUnfolding unf)
-> Just (noBinderInfo, env, unf)
other -> Nothing
- Just (occ_info, unfold_env, simple_unfolding) = maybe_unfolding_info
+ Just (occ_info, unf_env, simple_unfolding) = maybe_unfolding_info
SimpleUnfolding form guidance unf_template = simple_unfolding
- ---------- Specialisation stuff
+ ---------- Specialisation stuff
(ty_args, remaining_args) = initialTyArgs args
- maybe_specialisation = lookupSpecEnv (getIdSpecialisation var) ty_args
- (Just (spec_template, (spec_bindings, leftover_ty_args))) = maybe_specialisation
+ maybe_specialisation = lookupSpecEnv (getIdSpecialisation var) ty_args
+ Just (spec_bindings, spec_template) = maybe_specialisation
---------- Switches
sw_chkr = getSwitchChecker env
essential_unfoldings_only = switchIsOn sw_chkr EssentialUnfoldingsOnly
- always_inline = case guidance of {UnfoldAlways -> True; other -> False}
- ok_to_inline = okToInline form
- occ_info
- small_enough
- small_enough = smallEnoughToInline arg_evals guidance
- arg_evals = [is_evald arg | arg <- args, isValArg arg]
-
+ is_case_scrutinee = switchIsOn sw_chkr SimplCaseScrutinee
+ ok_to_inline = okToInline (whnfOrBottom form) small_enough occ_info
+ small_enough = smallEnoughToInline var arg_evals is_case_scrutinee guidance
+ arg_evals = [is_evald arg | arg <- args, isValArg arg]
+
is_evald (VarArg v) = isEvaluated (lookupRhsInfo env v)
is_evald (LitArg l) = True
-#if OMIT_DEFORESTER
- do_deforest = False
-#else
- do_deforest = case (getDeforestInfo (getIdInfo var)) of { DoDeforest -> True; _ -> False }
-#endif
+
+-- Perform the unfolding
+unfold var unf_env unf_template args result_ty
+ =
+{-
+ simplCount `thenSmpl` \ n ->
+ (if n > 1000 then
+ pprTrace "Ticks > 1000 and unfolding" (sep [space, int n, ppr var])
+ else
+ id
+ )
+ (if n>4000 then
+ returnSmpl (mkGenApp (Var var) args)
+ else
+-}
+ tickUnfold var `thenSmpl_`
+ simplExpr unf_env unf_template args result_ty
-- costCentreOk checks that it's ok to inline this thing
-- f x = let y = E in
-- scc "foo" (...y...)
--
--- Here y has a subsumed cost centre, and we can't inline it inside "foo",
+-- Here y has a "current cost centre", and we can't inline it inside "foo",
-- regardless of whether E is a WHNF or not.
costCentreOk cc_encl cc_rhs
- = noCostCentreAttached cc_encl || not (noCostCentreAttached cc_rhs)
+ = isCurrentCostCentre cc_encl || not (isCurrentCostCentre cc_rhs)
\end{code}
+
+%************************************************************************
+%* *
+\section{Dealing with a single binder}
+%* *
+%************************************************************************
+
+When we hit a binder we may need to
+ (a) apply the the type envt (if non-empty) to its type
+ (b) apply the type envt and id envt to its SpecEnv (if it has one)
+ (c) give it a new unique to avoid name clashes
+
+\begin{code}
+simplBinder :: SimplEnv -> InBinder -> SmplM (SimplEnv, OutId)
+simplBinder env (id, _)
+ | not_in_scope -- Not in scope, so no need to clone
+ && empty_ty_subst -- No type substitution to do inside the Id
+ && isNullIdEnv id_subst -- No id substitution to do inside the Id
+ = let
+ env' = setIdEnv env (addOneToIdEnv in_scope_ids id id, id_subst)
+ in
+ returnSmpl (env', id)
+
+ | otherwise
+ =
+#if DEBUG
+ -- I reckon the empty-env thing should catch
+ -- most no-free-tyvars things, so this test should be redundant
+ (if idHasNoFreeTyVars id then pprTrace "applyEnvsToId" (ppr id) else (\x -> x))
+#endif
+ (let
+ -- id1 has its type zapped
+ id1 | empty_ty_subst = id
+ | otherwise = mkIdWithNewType id ty'
+
+ -- id2 has its SpecEnv zapped
+ id2 | isEmptySpecEnv spec_env = id1
+ | otherwise = setIdSpecialisation id spec_env'
+ in
+ if not_in_scope then
+ -- No need to clone
+ let
+ env' = setIdEnv env (addOneToIdEnv in_scope_ids id id2, id_subst)
+ in
+ returnSmpl (env', id2)
+ else
+ -- Must clone
+ getUniqueSmpl `thenSmpl` \ uniq ->
+ let
+ id3 = mkIdWithNewUniq id2 uniq
+ env' = setIdEnv env (addOneToIdEnv in_scope_ids id3 id3,
+ addOneToIdEnv id_subst id (VarArg id3))
+ in
+ returnSmpl (env', id3)
+ )
+ where
+ ((in_scope_tyvars, ty_subst), (in_scope_ids, id_subst)) = getEnvs env
+ empty_ty_subst = isEmptyTyVarEnv ty_subst
+ not_in_scope = not (id `elemIdEnv` in_scope_ids)
+
+ ty = idType id
+ ty' = instantiateTy ty_subst ty
+
+ spec_env = getIdSpecialisation id
+ spec_env' = substSpecEnv ty_subst (substSpecEnvRhs ty_subst id_subst) spec_env
+
+simplBinders :: SimplEnv -> [InBinder] -> SmplM (SimplEnv, [OutId])
+simplBinders env binders = mapAccumLSmpl simplBinder env binders
+\end{code}
+
+\begin{code}
+simplTyBinder :: SimplEnv -> TyVar -> SmplM (SimplEnv, TyVar)
+simplTyBinder env tyvar
+ | not (tyvar `elementOfTyVarSet` tyvars) -- No need to clone
+ = let
+ env' = setTyEnv env (tyvars `addOneToTyVarSet` tyvar, ty_subst)
+ in
+ returnSmpl (env', tyvar)
+
+ | otherwise -- Need to clone
+ = getUniqueSmpl `thenSmpl` \ uniq ->
+ let
+ tyvar' = cloneTyVar tyvar uniq
+ env' = setTyEnv env (tyvars `addOneToTyVarSet` tyvar',
+ addToTyVarEnv ty_subst tyvar (mkTyVarTy tyvar'))
+ in
+ returnSmpl (env', tyvar')
+ where
+ ((tyvars, ty_subst), (ids, id_subst)) = getEnvs env
+
+simplTyBinders :: SimplEnv -> [TyVar] -> SmplM (SimplEnv, [TyVar])
+simplTyBinders env binders = mapAccumLSmpl simplTyBinder env binders
+\end{code}
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