\section[SimplCore]{Driver for simplifying @Core@ programs}
\begin{code}
-module SimplCore ( core2core ) where
+module SimplCore ( core2core, simplifyExpr ) where
#include "HsVersions.h"
-import CmdLineOpts ( CoreToDo(..), SimplifierSwitch(..),
- SwitchResult, switchIsOn,
- opt_D_dump_occur_anal,
- opt_D_dump_simpl_iterations,
- opt_D_simplifier_stats,
- opt_D_dump_simpl,
- opt_D_verbose_core2core,
- opt_D_dump_occur_anal
+import CmdLineOpts ( CoreToDo(..), SimplifierSwitch(..),
+ SimplifierMode(..), DynFlags, DynFlag(..), dopt,
+ dopt_CoreToDo
)
-import CoreLint ( beginPass, endPass )
import CoreSyn
-import PprCore ( pprCoreBindings )
-import OccurAnal ( occurAnalyseBinds )
-import CoreUtils ( exprIsTrivial, coreExprType )
-import Simplify ( simplBind )
-import SimplUtils ( etaCoreExpr, findDefault )
+import CoreFVs ( ruleRhsFreeVars )
+import HscTypes ( HscEnv(..), GhciMode(..),
+ ModGuts(..), ModGuts, Avails, availsToNameSet,
+ PackageRuleBase, HomePackageTable, ModDetails(..),
+ HomeModInfo(..)
+ )
+import CSE ( cseProgram )
+import Rules ( RuleBase, emptyRuleBase, ruleBaseFVs, ruleBaseIds,
+ extendRuleBaseList, addRuleBaseFVs, pprRuleBase,
+ ruleCheckProgram )
+import Module ( moduleEnvElts )
+import Name ( Name, isExternalName )
+import NameSet ( elemNameSet )
+import PprCore ( pprCoreBindings, pprCoreExpr )
+import OccurAnal ( occurAnalyseBinds, occurAnalyseGlobalExpr )
+import CoreUtils ( coreBindsSize )
+import Simplify ( simplTopBinds, simplExpr )
+import SimplUtils ( simplBinders )
import SimplMonad
-import CoreUnfold
-import Const ( Con(..), Literal(..), literalType, mkMachInt )
-import ErrUtils ( dumpIfSet )
+import ErrUtils ( dumpIfSet, dumpIfSet_dyn, showPass )
+import CoreLint ( endPass )
import FloatIn ( floatInwards )
import FloatOut ( floatOutwards )
-import Id ( Id, mkSysLocal, mkUserId,
- setIdVisibility, setIdUnfolding,
- getIdSpecialisation, setIdSpecialisation,
- getInlinePragma, setInlinePragma,
- idType, setIdType
- )
-import IdInfo ( InlinePragInfo(..) )
-import VarEnv
+import Id ( idName, setIdLocalExported )
import VarSet
-import Name ( isExported, mkSysLocalName,
- Module, NamedThing(..), OccName(..)
- )
-import TyCon ( TyCon, isDataTyCon )
-import PrimOp ( PrimOp(..) )
-import PrelInfo ( unpackCStringId, unpackCString2Id,
- integerZeroId, integerPlusOneId,
- integerPlusTwoId, integerMinusOneId,
- int2IntegerId, addr2IntegerId
- )
-import Type ( Type, splitAlgTyConApp_maybe,
- isUnLiftedType, mkTyVarTy, Type )
-import TysWiredIn ( isIntegerTy )
import LiberateCase ( liberateCase )
-import PprType ( nmbrType )
import SAT ( doStaticArgs )
import Specialise ( specProgram)
-import SpecEnv ( specEnvToList, specEnvFromList )
-import StrictAnal ( saWwTopBinds )
-import Var ( TyVar, setTyVarName )
-import Unique ( Unique, Uniquable(..),
- ratioTyConKey, mkUnique, incrUnique, initTidyUniques
- )
-import UniqSupply ( UniqSupply, splitUniqSupply )
-import Constants ( tARGET_MIN_INT, tARGET_MAX_INT )
-import Bag
-import Maybes
+import SpecConstr ( specConstrProgram)
+import DmdAnal ( dmdAnalPgm )
+import WorkWrap ( wwTopBinds )
+#ifdef OLD_STRICTNESS
+import StrictAnal ( saBinds )
+import CprAnalyse ( cprAnalyse )
+#endif
+
+import UniqSupply ( UniqSupply, mkSplitUniqSupply, splitUniqSupply )
import IO ( hPutStr, stderr )
import Outputable
-\end{code}
-
-\begin{code}
-core2core :: [CoreToDo] -- Spec of what core-to-core passes to do
- -> FAST_STRING -- Module name (profiling only)
- -> UniqSupply -- A name supply
- -> [CoreBind] -- Input
- -> IO [CoreBind] -- Result
-
-core2core core_todos module_name us binds
- = do
- -- Do the main business
- processed_binds <- doCorePasses us binds core_todos
- -- Do the final tidy-up
- final_binds <- tidyCorePgm module_name processed_binds
-
- -- Return results
- return final_binds
-
-doCorePasses us binds []
- = return binds
-
-doCorePasses us binds (to_do : to_dos)
- = do
- let (us1, us2) = splitUniqSupply us
- binds1 <- doCorePass us1 binds to_do
- doCorePasses us2 binds1 to_dos
-
-doCorePass us binds (CoreDoSimplify sw_chkr) = _scc_ "Simplify" simplifyPgm sw_chkr us binds
-doCorePass us binds CoreLiberateCase = _scc_ "LiberateCase" liberateCase binds
-doCorePass us binds CoreDoFloatInwards = _scc_ "FloatInwards" floatInwards binds
-doCorePass us binds CoreDoFullLaziness = _scc_ "CoreFloating" floatOutwards us binds
-doCorePass us binds CoreDoStaticArgs = _scc_ "CoreStaticArgs" doStaticArgs us binds
-doCorePass us binds CoreDoStrictness = _scc_ "CoreStranal" saWwTopBinds us binds
-doCorePass us binds CoreDoSpecialising = _scc_ "Specialise" specProgram us binds
+import Maybes ( orElse )
+import List ( partition )
\end{code}
-
%************************************************************************
%* *
\subsection{The driver for the simplifier}
%************************************************************************
\begin{code}
-simplifyPgm :: (SimplifierSwitch -> SwitchResult)
- -> UniqSupply
- -> [CoreBind] -- Input
- -> IO [CoreBind] -- New bindings
-
-simplifyPgm sw_chkr us binds
- = do {
- beginPass "Simplify";
-
- (termination_msg, it_count, counts, binds') <- iteration us 1 zeroSimplCount binds;
-
- dumpIfSet opt_D_simplifier_stats "Simplifier statistics"
- (vcat [text termination_msg <+> text "after" <+> ppr it_count <+> text "iterations",
- text "",
- pprSimplCount counts]);
-
- endPass "Simplify"
- (opt_D_verbose_core2core && not opt_D_dump_simpl_iterations)
- binds'
- }
- where
- max_iterations = getSimplIntSwitch sw_chkr MaxSimplifierIterations
- simpl_switch_is_on = switchIsOn sw_chkr
-
- core_iter_dump binds | opt_D_verbose_core2core = pprCoreBindings binds
- | otherwise = empty
-
- iteration us iteration_no counts binds
- = do {
- -- Occurrence analysis
- let { tagged_binds = _scc_ "OccAnal" occurAnalyseBinds simpl_switch_is_on binds };
- dumpIfSet opt_D_dump_occur_anal "Occurrence analysis"
- (pprCoreBindings tagged_binds);
-
- -- Simplify
- let { (binds', counts') = initSmpl sw_chkr us1 (simplTopBinds tagged_binds);
- all_counts = counts `plusSimplCount` counts'
- } ;
-
- -- Stop if nothing happened; don't dump output
- if isZeroSimplCount counts' then
- return ("Simplifier reached fixed point", iteration_no, all_counts, binds')
- else do {
-
- -- Dump the result of this iteration
- dumpIfSet opt_D_dump_simpl_iterations
- ("Simplifier iteration " ++ show iteration_no
- ++ " out of " ++ show max_iterations)
- (vcat[pprSimplCount counts',
- text "",
- core_iter_dump binds']) ;
-
- -- Stop if we've run out of iterations
- if iteration_no == max_iterations then
- do {
- if max_iterations > 1 then
- hPutStr stderr ("NOTE: Simplifier still going after " ++
- show max_iterations ++
- " iterations; bailing out.\n")
- else return ();
-
- return ("Simplifier baled out", iteration_no, all_counts, binds')
- }
-
- -- Else loop
- else iteration us2 (iteration_no + 1) all_counts binds'
- } }
- where
- (us1, us2) = splitUniqSupply us
-
-
-simplTopBinds [] = returnSmpl []
-simplTopBinds (bind1 : binds) = (simplBind bind1 $
- simplTopBinds binds) `thenSmpl` \ (binds1', binds') ->
- returnSmpl (binds1' ++ binds')
-\end{code}
-
-
-%************************************************************************
-%* *
-\subsection[SimplCore-indirections]{Eliminating indirections in Core code, and globalising}
-%* *
-%************************************************************************
-
-Several tasks are done by @tidyCorePgm@
-
-----------------
- [March 98] Indirections are now elimianted by the occurrence analyser
- -- 1. Eliminate indirections. The point here is to transform
- -- x_local = E
- -- x_exported = x_local
- -- ==>
- -- x_exported = E
-
-2. Make certain top-level bindings into Globals. The point is that
- Global things get externally-visible labels at code generation
- time
-
-3. Make the representation of NoRep literals explicit, and
- float their bindings to the top level. We only do the floating
- part for NoRep lits inside a lambda (else no gain). We need to
- take care with let x = "foo" in e
- that we don't end up with a silly binding
- let x = y in e
- with a floated "foo". What a bore.
-
-4. Convert
- case x of {...; x' -> ...x'...}
- ==>
- case x of {...; _ -> ...x... }
- See notes in SimplCase.lhs, near simplDefault for the reasoning here.
-
-5. *Mangle* cases involving par# in the discriminant. The unfolding
- for par in PrelConc.lhs include case expressions with integer
- results solely to fool the strictness analyzer, the simplifier,
- and anyone else who might want to fool with the evaluation order.
- At this point in the compiler our evaluation order is safe.
- Therefore, we convert expressions of the form:
-
- case par# e of
- 0# -> rhs
- _ -> parError#
- ==>
- case par# e of
- _ -> rhs
-
- fork# isn't handled like this - it's an explicit IO operation now.
- The reason is that fork# returns a ThreadId#, which gets in the
- way of the above scheme. And anyway, IO is the only guaranteed
- way to enforce ordering --SDM.
-
-6. Mangle cases involving seq# in the discriminant. Up to this
- point, seq# will appear like this:
-
- case seq# e of
- 0# -> seqError#
- _ -> ...
-
- where the 0# branch is purely to bamboozle the strictness analyser
- (see case 5 above). This code comes from an unfolding for 'seq'
- in Prelude.hs. We translate this into
+core2core :: HscEnv
+ -> PackageRuleBase
+ -> ModGuts
+ -> IO ModGuts
+
+core2core hsc_env pkg_rule_base
+ mod_impl@(ModGuts { mg_exports = exports,
+ mg_binds = binds_in,
+ mg_rules = rules_in })
+ = do
+ let dflags = hsc_dflags hsc_env
+ hpt = hsc_HPT hsc_env
+ ghci_mode = hsc_mode hsc_env
+ core_todos = dopt_CoreToDo dflags
- case e of
- _ -> ...
+ us <- mkSplitUniqSupply 's'
+ let (cp_us, ru_us) = splitUniqSupply us
- Now that the evaluation order is safe. The code generator knows
- how to push a seq frame on the stack if 'e' is of function type,
- or is polymorphic.
+ -- COMPUTE THE RULE BASE TO USE
+ (rule_base, local_rule_ids, orphan_rules, rule_rhs_fvs)
+ <- prepareRules dflags pkg_rule_base hpt ru_us binds_in rules_in
+ -- PREPARE THE BINDINGS
+ let binds1 = updateBinders ghci_mode local_rule_ids
+ rule_rhs_fvs exports binds_in
-7. Do eta reduction for lambda abstractions appearing in:
- - the RHS of case alternatives
- - the body of a let
+ -- DO THE BUSINESS
+ (stats, processed_binds)
+ <- doCorePasses dflags rule_base (zeroSimplCount dflags) cp_us binds1 core_todos
- These will otherwise turn into local bindings during Core->STG;
- better to nuke them if possible. (In general the simplifier does
- eta expansion not eta reduction, up to this point.)
+ dumpIfSet_dyn dflags Opt_D_dump_simpl_stats
+ "Grand total simplifier statistics"
+ (pprSimplCount stats)
-9. Give all binders a nice print-name. Their uniques aren't changed;
- rather we give them lexically unique occ-names, so that we can
- safely print the OccNae only in the interface file. [Bad idea to
- change the uniques, because the code generator makes global labels
- from the uniques for local thunks etc.]
+ -- Return results
+ -- We only return local orphan rules, i.e., local rules not attached to an Id
+ -- The bindings cotain more rules, embedded in the Ids
+ return (mod_impl { mg_binds = processed_binds, mg_rules = orphan_rules})
-Special case
-~~~~~~~~~~~~
+simplifyExpr :: DynFlags -- includes spec of what core-to-core passes to do
+ -> CoreExpr
+ -> IO CoreExpr
+-- simplifyExpr is called by the driver to simplify an
+-- expression typed in at the interactive prompt
+simplifyExpr dflags expr
+ = do {
+ ; showPass dflags "Simplify"
-NOT ENABLED AT THE MOMENT (because the floated Ids are global-ish
-things, and we need local Ids for non-floated stuff):
+ ; us <- mkSplitUniqSupply 's'
- Don't float stuff out of a binder that's marked as a bottoming Id.
- Reason: it doesn't do any good, and creates more CAFs that increase
- the size of SRTs.
+ ; let env = emptySimplEnv SimplGently [] emptyVarSet
+ (expr', _counts) = initSmpl dflags us (simplExprGently env expr)
-eg.
+ ; dumpIfSet_dyn dflags Opt_D_dump_simpl "Simplified expression"
+ (pprCoreExpr expr')
- f = error "string"
+ ; return expr'
+ }
-is translated to
- f' = unpackCString# "string"
- f = error f'
+doCorePasses :: DynFlags
+ -> RuleBase -- the main rule base
+ -> SimplCount -- simplifier stats
+ -> UniqSupply -- uniques
+ -> [CoreBind] -- local binds in (with rules attached)
+ -> [CoreToDo] -- which passes to do
+ -> IO (SimplCount, [CoreBind]) -- stats, binds, local orphan rules
-hence f' and f become CAFs. Instead, the special case for
-tidyTopBinding below makes sure this comes out as
+doCorePasses dflags rb stats us binds []
+ = return (stats, binds)
- f = let f' = unpackCString# "string" in error f'
+doCorePasses dflags rb stats us binds (to_do : to_dos)
+ = do
+ let (us1, us2) = splitUniqSupply us
+
+ (stats1, binds1) <- doCorePass dflags rb us1 binds to_do
+
+ doCorePasses dflags rb (stats `plusSimplCount` stats1) us2 binds1 to_dos
+
+doCorePass dfs rb us binds (CoreDoSimplify mode switches)
+ = _scc_ "Simplify" simplifyPgm dfs rb mode switches us binds
+doCorePass dfs rb us binds CoreCSE
+ = _scc_ "CommonSubExpr" noStats dfs (cseProgram dfs binds)
+doCorePass dfs rb us binds CoreLiberateCase
+ = _scc_ "LiberateCase" noStats dfs (liberateCase dfs binds)
+doCorePass dfs rb us binds CoreDoFloatInwards
+ = _scc_ "FloatInwards" noStats dfs (floatInwards dfs binds)
+doCorePass dfs rb us binds (CoreDoFloatOutwards f)
+ = _scc_ "FloatOutwards" noStats dfs (floatOutwards dfs f us binds)
+doCorePass dfs rb us binds CoreDoStaticArgs
+ = _scc_ "StaticArgs" noStats dfs (doStaticArgs us binds)
+doCorePass dfs rb us binds CoreDoStrictness
+ = _scc_ "Stranal" noStats dfs (dmdAnalPgm dfs binds)
+doCorePass dfs rb us binds CoreDoWorkerWrapper
+ = _scc_ "WorkWrap" noStats dfs (wwTopBinds dfs us binds)
+doCorePass dfs rb us binds CoreDoSpecialising
+ = _scc_ "Specialise" noStats dfs (specProgram dfs us binds)
+doCorePass dfs rb us binds CoreDoSpecConstr
+ = _scc_ "SpecConstr" noStats dfs (specConstrProgram dfs us binds)
+#ifdef OLD_STRICTNESS
+doCorePass dfs rb us binds CoreDoOldStrictness
+ = _scc_ "OldStrictness" noStats dfs (doOldStrictness dfs binds)
+#endif
+doCorePass dfs rb us binds CoreDoPrintCore
+ = _scc_ "PrintCore" noStats dfs (printCore binds)
+doCorePass dfs rb us binds CoreDoGlomBinds
+ = noStats dfs (glomBinds dfs binds)
+doCorePass dfs rb us binds (CoreDoRuleCheck phase pat)
+ = noStats dfs (ruleCheck dfs phase pat binds)
+doCorePass dfs rb us binds CoreDoNothing
+ = noStats dfs (return binds)
+
+#ifdef OLD_STRICTNESS
+doOldStrictness dfs binds
+ = do binds1 <- saBinds dfs binds
+ binds2 <- cprAnalyse dfs binds1
+ return binds2
+#endif
+
+printCore binds = do dumpIfSet True "Print Core"
+ (pprCoreBindings binds)
+ return binds
+
+ruleCheck dflags phase pat binds = do showPass dflags "RuleCheck"
+ printDump (ruleCheckProgram phase pat binds)
+ return binds
+
+-- most passes return no stats and don't change rules
+noStats dfs thing = do { binds <- thing; return (zeroSimplCount dfs, binds) }
-and we can safely ignore f as a CAF, since it can only ever be entered once.
+\end{code}
-\begin{code}
-tidyCorePgm :: Module -> [CoreBind] -> IO [CoreBind]
-tidyCorePgm mod binds_in
- = do
- beginPass "Tidy Core"
+%************************************************************************
+%* *
+\subsection{Dealing with rules}
+%* *
+%************************************************************************
- let binds_out = bagToList (initTM mod (tidyTopBindings binds_in))
+-- prepareLocalRuleBase takes the CoreBinds and rules defined in this module.
+-- It attaches those rules that are for local Ids to their binders, and
+-- returns the remainder attached to Ids in an IdSet. It also returns
+-- Ids mentioned on LHS of some rule; these should be blacklisted.
- endPass "Tidy Core" (opt_D_dump_simpl || opt_D_verbose_core2core) binds_out
-\end{code}
+-- The rule Ids and LHS Ids are black-listed; that is, they aren't inlined
+-- so that the opportunity to apply the rule isn't lost too soon
-Top level bindings
-~~~~~~~~~~~~~~~~~~
\begin{code}
-tidyTopBindings [] = returnTM emptyBag
-tidyTopBindings (b:bs)
- = tidyTopBinding b $
- tidyTopBindings bs
-
-tidyTopBinding :: CoreBind
- -> TopTidyM (Bag CoreBind)
- -> TopTidyM (Bag CoreBind)
-
-tidyTopBinding (NonRec bndr rhs) thing_inside
- = initNestedTM (tidyCoreExpr rhs) `thenTM` \ (rhs',floats) ->
- tidyTopBinder bndr $ \ bndr' ->
- thing_inside `thenTM` \ binds ->
- let
- this_bind {- | isBottomingId bndr
- = unitBag (NonRec bndr' (foldrBag Let rhs' floats))
- | otherwise -}
- = floats `snocBag` NonRec bndr' rhs'
- in
- returnTM (this_bind `unionBags` binds)
-
-tidyTopBinding (Rec pairs) thing_inside
- = tidyTopBinders binders $ \ binders' ->
- initNestedTM (mapTM tidyCoreExpr rhss) `thenTM` \ (rhss', floats) ->
- thing_inside `thenTM` \ binds_inside ->
- returnTM ((floats `snocBag` Rec (binders' `zip` rhss')) `unionBags` binds_inside)
+prepareRules :: DynFlags -> PackageRuleBase -> HomePackageTable
+ -> UniqSupply
+ -> [CoreBind]
+ -> [IdCoreRule] -- Local rules
+ -> IO (RuleBase, -- Full rule base
+ IdSet, -- Local rule Ids
+ [IdCoreRule], -- Orphan rules
+ IdSet) -- RHS free vars of all rules
+
+prepareRules dflags pkg_rule_base hpt us binds local_rules
+ = do { let env = emptySimplEnv SimplGently [] local_ids
+ (better_rules,_) = initSmpl dflags us (mapSmpl (simplRule env) local_rules)
+
+ ; let (local_rules, orphan_rules) = partition ((`elemVarSet` local_ids) . fst) better_rules
+ -- We use (`elemVarSet` local_ids) rather than isLocalId because
+ -- isLocalId isn't true of class methods.
+ -- If we miss any rules for Ids defined here, then we end up
+ -- giving the local decl a new Unique (because the in-scope-set is the
+ -- same as the rule-id set), and now the binding for the class method
+ -- doesn't have the same Unique as the one in the Class and the tc-env
+ -- Example: class Foo a where
+ -- op :: a -> a
+ -- {-# RULES "op" op x = x #-}
+
+ rule_rhs_fvs = unionVarSets (map (ruleRhsFreeVars . snd) better_rules)
+ local_rule_base = extendRuleBaseList emptyRuleBase local_rules
+ local_rule_ids = ruleBaseIds local_rule_base -- Local Ids with rules attached
+ imp_rule_base = foldl add_rules pkg_rule_base (moduleEnvElts hpt)
+ rule_base = extendRuleBaseList imp_rule_base orphan_rules
+ final_rule_base = addRuleBaseFVs rule_base (ruleBaseFVs local_rule_base)
+ -- The last step black-lists the free vars of local rules too
+
+ ; dumpIfSet_dyn dflags Opt_D_dump_rules "Transformation rules"
+ (vcat [text "Local rules", pprRuleBase local_rule_base,
+ text "",
+ text "Imported rules", pprRuleBase final_rule_base])
+
+ ; return (final_rule_base, local_rule_ids, orphan_rules, rule_rhs_fvs)
+ }
where
- (binders, rhss) = unzip pairs
+ add_rules rule_base mod_info = extendRuleBaseList rule_base (md_rules (hm_details mod_info))
+
+ -- Boringly, we need to gather the in-scope set.
+ local_ids = foldr (unionVarSet . mkVarSet . bindersOf) emptyVarSet binds
+
+
+updateBinders :: GhciMode
+ -> IdSet -- Locally defined ids with their Rules attached
+ -> IdSet -- Ids free in the RHS of local rules
+ -> Avails -- What is exported
+ -> [CoreBind] -> [CoreBind]
+ -- A horrible function
+
+-- Update the binders of top-level bindings as follows
+-- a) Attach the rules for each locally-defined Id to that Id.
+-- b) Set the no-discard flag if either the Id is exported,
+-- or it's mentioned in the RHS of a rule
+--
+-- You might wonder why exported Ids aren't already marked as such;
+-- it's just because the type checker is rather busy already and
+-- I didn't want to pass in yet another mapping.
+--
+-- Reason for (a)
+-- - It makes the rules easier to look up
+-- - It means that transformation rules and specialisations for
+-- locally defined Ids are handled uniformly
+-- - It keeps alive things that are referred to only from a rule
+-- (the occurrence analyser knows about rules attached to Ids)
+-- - It makes sure that, when we apply a rule, the free vars
+-- of the RHS are more likely to be in scope
+--
+-- Reason for (b)
+-- It means that the binding won't be discarded EVEN if the binding
+-- ends up being trivial (v = w) -- the simplifier would usually just
+-- substitute w for v throughout, but we don't apply the substitution to
+-- the rules (maybe we should?), so this substitution would make the rule
+-- bogus.
+
+updateBinders ghci_mode rule_ids rule_rhs_fvs exports binds
+ = map update_bndrs binds
+ where
+ update_bndrs (NonRec b r) = NonRec (update_bndr b) r
+ update_bndrs (Rec prs) = Rec [(update_bndr b, r) | (b,r) <- prs]
+
+ update_bndr bndr
+ | dont_discard bndr = setIdLocalExported bndr_with_rules
+ | otherwise = bndr_with_rules
+ where
+ bndr_with_rules = lookupVarSet rule_ids bndr `orElse` bndr
+
+ dont_discard bndr = is_exported (idName bndr)
+ || bndr `elemVarSet` rule_rhs_fvs
+
+ -- In interactive mode, we don't want to discard any top-level
+ -- entities at all (eg. do not inline them away during
+ -- simplification), and retain them all in the TypeEnv so they are
+ -- available from the command line.
+ --
+ -- isExternalName separates the user-defined top-level names from those
+ -- introduced by the type checker.
+ is_exported :: Name -> Bool
+ is_exported | ghci_mode == Interactive = isExternalName
+ | otherwise = (`elemNameSet` export_fvs)
+
+ export_fvs = availsToNameSet exports
\end{code}
+
+We must do some gentle simplification on the template (but not the RHS)
+of each rule. The case that forced me to add this was the fold/build rule,
+which without simplification looked like:
+ fold k z (build (/\a. g a)) ==> ...
+This doesn't match unless you do eta reduction on the build argument.
+
\begin{code}
-tidyTopBinder :: Id -> (Id -> TopTidyM (Bag CoreBind)) -> TopTidyM (Bag CoreBind)
-tidyTopBinder id thing_inside
- = mungeTopBndr id $ \ id' ->
- let
- spec_items = specEnvToList (getIdSpecialisation id')
- in
- if null spec_items then
-
- -- Common case, no specialisations to tidy
- thing_inside id'
- else
-
- -- Oh well, tidy those specialisations
- initNestedTM (mapTM tidySpecItem spec_items) `thenTM` \ (spec_items', floats) ->
- let
- id'' = setIdSpecialisation id' (specEnvFromList spec_items')
- in
- extendEnvTM id (Var id'') $
- thing_inside id'' `thenTM` \ binds ->
- returnTM (floats `unionBags` binds)
-
-tidyTopBinders [] k = k []
-tidyTopBinders (b:bs) k = tidyTopBinder b $ \ b' ->
- tidyTopBinders bs $ \ bs' ->
- k (b' : bs')
-
-tidySpecItem (tyvars, tys, rhs)
- = newBndrs tyvars $ \ tyvars' ->
- mapTM tidyTy tys `thenTM` \ tys' ->
- tidyCoreExpr rhs `thenTM` \ rhs' ->
- returnTM (tyvars', tys', rhs')
+simplRule env rule@(id, BuiltinRule _ _)
+ = returnSmpl rule
+simplRule env rule@(id, Rule act name bndrs args rhs)
+ = simplBinders env bndrs `thenSmpl` \ (env, bndrs') ->
+ mapSmpl (simplExprGently env) args `thenSmpl` \ args' ->
+ simplExprGently env rhs `thenSmpl` \ rhs' ->
+ returnSmpl (id, Rule act name bndrs' args' rhs')
+
+-- It's important that simplExprGently does eta reduction.
+-- For example, in a rule like:
+-- augment g (build h)
+-- we do not want to get
+-- augment (\a. g a) (build h)
+-- otherwise we don't match when given an argument like
+-- (\a. h a a)
+--
+-- The simplifier does indeed do eta reduction (it's in
+-- Simplify.completeLam) but only if -O is on.
\end{code}
-Expressions
-~~~~~~~~~~~
\begin{code}
-tidyCoreExpr (Var v) = lookupId v
-
-tidyCoreExpr (Type ty)
- = tidyTy ty `thenTM` \ ty' ->
- returnTM (Type ty')
-
-tidyCoreExpr (App fun arg)
- = tidyCoreExpr fun `thenTM` \ fun' ->
- tidyCoreExpr arg `thenTM` \ arg' ->
- returnTM (App fun' arg')
-
-tidyCoreExpr (Con (Literal lit) args)
- = ASSERT( null args )
- litToRep lit `thenTM` \ (lit_ty, lit_expr) ->
- getInsideLambda `thenTM` \ in_lam ->
- if in_lam && not (exprIsTrivial lit_expr) then
- -- It must have been a no-rep literal with a
- -- non-trivial representation; and we're inside a lambda;
- -- so float it to the top
- addTopFloat lit_ty lit_expr `thenTM` \ v ->
- returnTM (Var v)
- else
- returnTM lit_expr
-
-tidyCoreExpr (Con con args)
- = mapTM tidyCoreExpr args `thenTM` \ args' ->
- returnTM (Con con args')
-
-tidyCoreExpr (Lam bndr body)
- = newBndr bndr $ \ bndr' ->
- insideLambda bndr $
- tidyCoreExpr body `thenTM` \ body' ->
- returnTM (Lam bndr' body')
-
-tidyCoreExpr (Let (NonRec bndr rhs) body)
- = tidyCoreExpr rhs `thenTM` \ rhs' ->
- tidyBindNonRec bndr rhs' body
-
-tidyCoreExpr (Let (Rec pairs) body)
- = newBndrs bndrs $ \ bndrs' ->
- mapTM tidyCoreExpr rhss `thenTM` \ rhss' ->
- tidyCoreExprEta body `thenTM` \ body' ->
- returnTM (Let (Rec (bndrs' `zip` rhss')) body')
- where
- (bndrs, rhss) = unzip pairs
-
-tidyCoreExpr (Note (Coerce to_ty from_ty) body)
- = tidyCoreExprEta body `thenTM` \ body' ->
- tidyTy to_ty `thenTM` \ to_ty' ->
- tidyTy from_ty `thenTM` \ from_ty' ->
- returnTM (Note (Coerce to_ty' from_ty') body')
-
-tidyCoreExpr (Note note body)
- = tidyCoreExprEta body `thenTM` \ body' ->
- returnTM (Note note body')
-
--- seq#: see notes above.
-tidyCoreExpr (Case scrut@(Con (PrimOp SeqOp) [Type _, e]) bndr alts)
- = tidyCoreExpr e `thenTM` \ e' ->
- newBndr bndr $ \ bndr' ->
- let new_bndr = setIdType bndr' (coreExprType e') in
- tidyCoreExprEta default_rhs `thenTM` \ rhs' ->
- returnTM (Case e' new_bndr [(DEFAULT,[],rhs')])
- where
- (other_alts, maybe_default) = findDefault alts
- Just default_rhs = maybe_default
-
--- par#: see notes above.
-tidyCoreExpr (Case scrut@(Con (PrimOp op) args) bndr alts)
- | funnyParallelOp op && maybeToBool maybe_default
- = tidyCoreExpr scrut `thenTM` \ scrut' ->
- newBndr bndr $ \ bndr' ->
- tidyCoreExprEta default_rhs `thenTM` \ rhs' ->
- returnTM (Case scrut' bndr' [(DEFAULT,[],rhs')])
- where
- (other_alts, maybe_default) = findDefault alts
- Just default_rhs = maybe_default
-
-tidyCoreExpr (Case scrut case_bndr alts)
- = tidyCoreExpr scrut `thenTM` \ scrut' ->
- newBndr case_bndr $ \ case_bndr' ->
- mapTM tidy_alt alts `thenTM` \ alts' ->
- returnTM (Case scrut' case_bndr' alts')
- where
- tidy_alt (con,bndrs,rhs) = newBndrs bndrs $ \ bndrs' ->
- tidyCoreExprEta rhs `thenTM` \ rhs' ->
- returnTM (con, bndrs', rhs')
-
-tidyCoreExprEta e = tidyCoreExpr e `thenTM` \ e' ->
- returnTM (etaCoreExpr e')
-
-tidyBindNonRec bndr val' body
- | exprIsTrivial val'
- = extendEnvTM bndr val' (tidyCoreExpr body)
-
- | otherwise
- = newBndr bndr $ \ bndr' ->
- tidyCoreExpr body `thenTM` \ body' ->
- returnTM (Let (NonRec bndr' val') body')
+simplExprGently :: SimplEnv -> CoreExpr -> SimplM CoreExpr
+-- Simplifies an expression
+-- does occurrence analysis, then simplification
+-- and repeats (twice currently) because one pass
+-- alone leaves tons of crud.
+-- Used (a) for user expressions typed in at the interactive prompt
+-- (b) the LHS and RHS of a RULE
+--
+-- The name 'Gently' suggests that the SimplifierMode is SimplGently,
+-- and in fact that is so.... but the 'Gently' in simplExprGently doesn't
+-- enforce that; it just simplifies the expression twice
+
+simplExprGently env expr
+ = simplExpr env (occurAnalyseGlobalExpr expr) `thenSmpl` \ expr1 ->
+ simplExpr env (occurAnalyseGlobalExpr expr1)
\end{code}
%************************************************************************
%* *
-\subsection[coreToStg-lits]{Converting literals}
+\subsection{Glomming}
%* *
%************************************************************************
-Literals: the NoRep kind need to be de-no-rep'd.
-We always replace them with a simple variable, and float a suitable
-binding out to the top level.
-
\begin{code}
-
-litToRep :: Literal -> NestTidyM (Type, CoreExpr)
-
-litToRep (NoRepStr s ty)
- = returnTM (ty, rhs)
- where
- rhs = if (any is_NUL (_UNPK_ s))
-
- then -- Must cater for NULs in literal string
- mkApps (Var unpackCString2Id)
- [mkLit (MachStr s),
- mkLit (mkMachInt (toInteger (_LENGTH_ s)))]
-
- else -- No NULs in the string
- App (Var unpackCStringId) (mkLit (MachStr s))
-
- is_NUL c = c == '\0'
-\end{code}
-
-If an Integer is small enough (Haskell implementations must support
-Ints in the range $[-2^29+1, 2^29-1]$), wrap it up in @int2Integer@;
-otherwise, wrap with @litString2Integer@.
-
-\begin{code}
-litToRep (NoRepInteger i integer_ty)
- = returnTM (integer_ty, rhs)
- where
- rhs | i == 0 = Var integerZeroId -- Extremely convenient to look out for
- | i == 1 = Var integerPlusOneId -- a few very common Integer literals!
- | i == 2 = Var integerPlusTwoId
- | i == (-1) = Var integerMinusOneId
-
- | i > tARGET_MIN_INT && -- Small enough, so start from an Int
- i < tARGET_MAX_INT
- = App (Var int2IntegerId) (Con (Literal (mkMachInt i)) [])
-
- | otherwise -- Big, so start from a string
- = App (Var addr2IntegerId) (Con (Literal (MachStr (_PK_ (show i)))) [])
-
-
-litToRep (NoRepRational r rational_ty)
- = tidyCoreExpr (mkLit (NoRepInteger (numerator r) integer_ty)) `thenTM` \ num_arg ->
- tidyCoreExpr (mkLit (NoRepInteger (denominator r) integer_ty)) `thenTM` \ denom_arg ->
- returnTM (rational_ty, mkConApp ratio_data_con [Type integer_ty, num_arg, denom_arg])
- where
- (ratio_data_con, integer_ty)
- = case (splitAlgTyConApp_maybe rational_ty) of
- Just (tycon, [i_ty], [con])
- -> ASSERT(isIntegerTy i_ty && getUnique tycon == ratioTyConKey)
- (con, i_ty)
-
- _ -> (panic "ratio_data_con", panic "integer_ty")
-
-litToRep other_lit = returnTM (literalType other_lit, mkLit other_lit)
+glomBinds :: DynFlags -> [CoreBind] -> IO [CoreBind]
+-- Glom all binds together in one Rec, in case any
+-- transformations have introduced any new dependencies
+--
+-- NB: the global invariant is this:
+-- *** the top level bindings are never cloned, and are always unique ***
+--
+-- We sort them into dependency order, but applying transformation rules may
+-- make something at the top refer to something at the bottom:
+-- f = \x -> p (q x)
+-- h = \y -> 3
+--
+-- RULE: p (q x) = h x
+--
+-- Applying this rule makes f refer to h,
+-- although it doesn't appear to in the source program.
+-- This pass lets us control where it happens.
+--
+-- NOTICE that this cannot happen for rules whose head is a locally-defined
+-- function. It only happens for rules whose head is an imported function
+-- (p in the example above). So, for example, the rule had been
+-- RULE: f (p x) = h x
+-- then the rule for f would be attached to f itself (in its IdInfo)
+-- by prepareLocalRuleBase and h would be regarded by the occurrency
+-- analyser as free in f.
+
+glomBinds dflags binds
+ = do { showPass dflags "GlomBinds" ;
+ let { recd_binds = [Rec (flattenBinds binds)] } ;
+ return recd_binds }
+ -- Not much point in printing the result...
+ -- just consumes output bandwidth
\end{code}
-\begin{code}
-funnyParallelOp ParOp = True
-funnyParallelOp _ = False
-\end{code}
-
%************************************************************************
%* *
-\subsection{The monad}
+\subsection{The driver for the simplifier}
%* *
%************************************************************************
\begin{code}
-type TidyM a state = Module
- -> Bool -- True <=> inside a *value* lambda
- -> (TyVarEnv Type, IdEnv CoreExpr, IdOrTyVarSet)
- -- Substitution and in-scope binders
- -> state
- -> (a, state)
-
-type TopTidyM a = TidyM a Unique
-type NestTidyM a = TidyM a (Unique, -- Global names
- Unique, -- Local names
- Bag CoreBind) -- Floats
-
-
-(initialTopTidyUnique, initialNestedTidyUnique) = initTidyUniques
-
-initTM :: Module -> TopTidyM a -> a
-initTM mod m
- = case m mod False {- not inside lambda -} empty_env initialTopTidyUnique of
- (result, _) -> result
- where
- empty_env = (emptyVarEnv, emptyVarEnv, emptyVarSet)
-
-initNestedTM :: NestTidyM a -> TopTidyM (a, Bag CoreBind)
-initNestedTM m mod in_lam env global_us
- = case m mod in_lam env (global_us, initialNestedTidyUnique, emptyBag) of
- (result, (global_us', _, floats)) -> ((result, floats), global_us')
-
-returnTM v mod in_lam env usf = (v, usf)
-thenTM m k mod in_lam env usf = case m mod in_lam env usf of
- (r, usf') -> k r mod in_lam env usf'
+simplifyPgm :: DynFlags
+ -> RuleBase
+ -> SimplifierMode
+ -> [SimplifierSwitch]
+ -> UniqSupply
+ -> [CoreBind] -- Input
+ -> IO (SimplCount, [CoreBind]) -- New bindings
-mapTM f [] = returnTM []
-mapTM f (x:xs) = f x `thenTM` \ r ->
- mapTM f xs `thenTM` \ rs ->
- returnTM (r:rs)
+simplifyPgm dflags rule_base
+ mode switches us binds
+ = do {
+ showPass dflags "Simplify";
-insideLambda :: CoreBndr -> NestTidyM a -> NestTidyM a
-insideLambda bndr m mod in_lam env usf | isId bndr = m mod True env usf
- | otherwise = m mod in_lam env usf
+ (termination_msg, it_count, counts_out, binds')
+ <- iteration us 1 (zeroSimplCount dflags) binds;
-getInsideLambda :: NestTidyM Bool
-getInsideLambda mod in_lam env usf = (in_lam, usf)
-\end{code}
-
-Need to extend the environment when we munge a binder, so that
-occurrences of the binder will print the correct way (e.g. as a global
-not a local).
+ dumpIfSet (dopt Opt_D_verbose_core2core dflags
+ && dopt Opt_D_dump_simpl_stats dflags)
+ "Simplifier statistics"
+ (vcat [text termination_msg <+> text "after" <+> ppr it_count <+> text "iterations",
+ text "",
+ pprSimplCount counts_out]);
-In cases where we don't clone the binder (because it's an exported
-id), we still zap the unfolding and inline pragma info so that
-unnecessary gumph isn't carried into the code generator. This fixes a
-nasty space leak.
+ endPass dflags "Simplify" Opt_D_verbose_core2core binds';
-\begin{code}
-mungeTopBndr id thing_inside mod in_lam env@(ty_env, val_env, in_scope) us
- = thing_inside id' mod in_lam (ty_env, val_env', in_scope') us'
+ return (counts_out, binds')
+ }
where
- (id', us') | isExported id = (zapSomeIdInfo id, us)
- | otherwise = (zapSomeIdInfo (setIdVisibility (Just mod) us id),
- incrUnique us)
- val_env' = extendVarEnv val_env id (Var id')
- in_scope' = extendVarSet in_scope id'
-
-zapSomeIdInfo id = id `setIdUnfolding` noUnfolding `setInlinePragma` new_ip
- where new_ip = case getInlinePragma id of
- ICanSafelyBeINLINEd _ _ -> NoInlinePragInfo
- something_else -> something_else
-
-addTopFloat :: Type -> CoreExpr -> NestTidyM Id
-addTopFloat lit_ty lit_rhs mod in_lam env (gus, lus, floats)
- = let
- gus' = incrUnique gus
- lit_local = mkSysLocal gus lit_ty
- lit_id = setIdVisibility (Just mod) gus lit_local
- in
- (lit_id, (gus', lus, floats `snocBag` NonRec lit_id lit_rhs))
-
-lookupId :: Id -> TidyM CoreExpr state
-lookupId v mod in_lam (_, val_env, _) usf
- = case lookupVarEnv val_env v of
- Nothing -> (Var v, usf)
- Just e -> (e, usf)
-
-extendEnvTM :: Id -> CoreExpr -> (TidyM a state) -> TidyM a state
-extendEnvTM v e m mod in_lam (ty_env, val_env, in_scope) usf
- = m mod in_lam (ty_env, extendVarEnv val_env v e, in_scope) usf
-\end{code}
+ phase_info = case mode of
+ SimplGently -> "gentle"
+ SimplPhase n -> show n
+
+ imported_rule_ids = ruleBaseIds rule_base
+ simpl_env = emptySimplEnv mode switches imported_rule_ids
+ sw_chkr = getSwitchChecker simpl_env
+ max_iterations = intSwitchSet sw_chkr MaxSimplifierIterations `orElse` 2
+
+ iteration us iteration_no counts binds
+ -- iteration_no is the number of the iteration we are
+ -- about to begin, with '1' for the first
+ | iteration_no > max_iterations -- Stop if we've run out of iterations
+ = do {
+#ifdef DEBUG
+ if max_iterations > 2 then
+ hPutStr stderr ("NOTE: Simplifier still going after " ++
+ show max_iterations ++
+ " iterations; bailing out.\n")
+ else
+ return ();
+#endif
+ -- Subtract 1 from iteration_no to get the
+ -- number of iterations we actually completed
+ return ("Simplifier baled out", iteration_no - 1, counts, binds)
+ }
+
+ -- Try and force thunks off the binds; significantly reduces
+ -- space usage, especially with -O. JRS, 000620.
+ | let sz = coreBindsSize binds in sz == sz
+ = do {
+ -- Occurrence analysis
+ let { tagged_binds = _scc_ "OccAnal" occurAnalyseBinds binds } ;
+ dumpIfSet_dyn dflags Opt_D_dump_occur_anal "Occurrence analysis"
+ (pprCoreBindings tagged_binds);
-Making new local binders
-~~~~~~~~~~~~~~~~~~~~~~~~
-\begin{code}
-newBndr tyvar thing_inside mod in_lam (ty_env, val_env, in_scope) (gus, local_uniq, floats)
- | isTyVar tyvar
- = let
- local_uniq' = incrUnique local_uniq
- tyvar' = setTyVarName tyvar (mkSysLocalName local_uniq)
- ty_env' = extendVarEnv ty_env tyvar (mkTyVarTy tyvar')
- in_scope' = extendVarSet in_scope tyvar'
- in
- thing_inside tyvar' mod in_lam (ty_env', val_env, in_scope') (gus, local_uniq', floats)
-
-newBndr id thing_inside mod in_lam (ty_env, val_env, in_scope) (gus, local_uniq, floats)
- | isId id
- = let
- -- Give the Id a fresh print-name, *and* rename its type
- local_uniq' = incrUnique local_uniq
- name' = mkSysLocalName local_uniq
- ty' = nmbrType ty_env local_uniq' (idType id)
-
- id' = mkUserId name' ty'
- -- NB: This throws away the IdInfo of the Id, which we
- -- no longer need. That means we don't need to
- -- run over it with env, nor renumber it.
-
- val_env' = extendVarEnv val_env id (Var id')
- in_scope' = extendVarSet in_scope id'
- in
- thing_inside id' mod in_lam (ty_env, val_env', in_scope') (gus, local_uniq', floats)
-
-newBndrs [] thing_inside
- = thing_inside []
-newBndrs (bndr:bndrs) thing_inside
- = newBndr bndr $ \ bndr' ->
- newBndrs bndrs $ \ bndrs' ->
- thing_inside (bndr' : bndrs')
-\end{code}
+ -- SIMPLIFY
+ -- We do this with a *case* not a *let* because lazy pattern
+ -- matching bit us with bad space leak!
+ -- With a let, we ended up with
+ -- let
+ -- t = initSmpl ...
+ -- counts' = snd t
+ -- in
+ -- case t of {(_,counts') -> if counts'=0 then ... }
+ -- So the conditional didn't force counts', because the
+ -- selection got duplicated. Sigh!
+ case initSmpl dflags us1 (simplTopBinds simpl_env tagged_binds) of {
+ (binds', counts') -> do {
+ -- The imported_rule_ids are used by initSmpl to initialise
+ -- the in-scope set. That way, the simplifier will change any
+ -- occurrences of the imported id to the one in the imported_rule_ids
+ -- set, which are decorated with their rules.
+
+ let { all_counts = counts `plusSimplCount` counts' ;
+ herald = "Simplifier phase " ++ phase_info ++
+ ", iteration " ++ show iteration_no ++
+ " out of " ++ show max_iterations
+ } ;
-Re-numbering types
-~~~~~~~~~~~~~~~~~~
-\begin{code}
-tidyTy ty mod in_lam (ty_env, val_env, in_scope) usf@(_, local_uniq, _)
- = (nmbrType ty_env local_uniq ty, usf)
- -- We can use local_uniq as a base for renaming forall'd variables
- -- in the type; we don't need to know how many are consumed.
-\end{code}
+ -- Stop if nothing happened; don't dump output
+ if isZeroSimplCount counts' then
+ return ("Simplifier reached fixed point", iteration_no, all_counts, binds')
+ else do {
+
+ -- Dump the result of this iteration
+ dumpIfSet_dyn dflags Opt_D_dump_simpl_iterations herald
+ (pprSimplCount counts') ;
--- Get rid of this function when we move to the new code generator.
+ endPass dflags herald Opt_D_dump_simpl_iterations binds' ;
-\begin{code}
-typeOkForCase :: Type -> Bool
-typeOkForCase ty
- | isUnLiftedType ty -- Primitive case
- = True
-
- | otherwise
- = case (splitAlgTyConApp_maybe ty) of
- Just (tycon, ty_args, []) -> False
- Just (tycon, ty_args, non_null_data_cons) | isDataTyCon tycon -> True
- other -> False
- -- Null data cons => type is abstract, which code gen can't
- -- currently handle. (ToDo: when return-in-heap is universal we
- -- don't need to worry about this.)
+ -- Loop
+ iteration us2 (iteration_no + 1) all_counts binds'
+ } } } }
+ where
+ (us1, us2) = splitUniqSupply us
\end{code}
projects / ghc-hetmet.git / blobdiff