\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(..), intSwitchSet,
- opt_UsageSPOn,
DynFlags, DynFlag(..), dopt, dopt_CoreToDo
)
import CoreLint ( showPass, endPass )
import CoreSyn
-import CoreFVs ( ruleSomeFreeVars )
-import HscTypes ( PackageRuleBase, HomeSymbolTable, ModDetails(..) )
+import CoreFVs ( ruleRhsFreeVars )
+import HscTypes ( PersistentCompilerState(..),
+ PackageRuleBase, HomeSymbolTable, IsExported, ModDetails(..)
+ )
import CSE ( cseProgram )
import Rules ( RuleBase, emptyRuleBase, ruleBaseFVs, ruleBaseIds,
extendRuleBaseList, addRuleBaseFVs )
import Module ( moduleEnvElts )
import CoreUnfold
-import PprCore ( pprCoreBindings, pprIdCoreRule )
-import OccurAnal ( occurAnalyseBinds )
-import CoreUtils ( etaReduceExpr, coreBindsSize )
+import PprCore ( pprCoreBindings, pprIdCoreRule, pprCoreExpr )
+import OccurAnal ( occurAnalyseBinds, occurAnalyseGlobalExpr )
+import CoreUtils ( coreBindsSize )
import Simplify ( simplTopBinds, simplExpr )
import SimplUtils ( simplBinders )
import SimplMonad
import ErrUtils ( dumpIfSet, dumpIfSet_dyn )
import FloatIn ( floatInwards )
import FloatOut ( floatOutwards )
-import Id ( Id, isDataConWrapId, setIdNoDiscard )
+import Id ( idName, isDataConWrapId, setIdNoDiscard, isLocalId )
import VarSet
import LiberateCase ( liberateCase )
import SAT ( doStaticArgs )
import Specialise ( specProgram)
+import SpecConstr ( specConstrProgram)
import UsageSPInf ( doUsageSPInf )
import StrictAnal ( saBinds )
import WorkWrap ( wwTopBinds )
import IO ( hPutStr, stderr )
import Outputable
+import Maybes ( orElse )
import List ( partition )
\end{code}
\begin{code}
core2core :: DynFlags -- includes spec of what core-to-core passes to do
- -> PackageRuleBase -- Rule-base accumulated from imported packages
+ -> PersistentCompilerState
-> HomeSymbolTable
+ -> IsExported
-> [CoreBind] -- Binds in
- -> [IdCoreRule] -- Rules in
+ -> [IdCoreRule] -- Rules defined in this module
-> IO ([CoreBind], [IdCoreRule]) -- binds, local orphan rules out
-core2core dflags pkg_rule_base hst binds rules
+core2core dflags pcs hst is_exported binds rules
= do
- let core_todos = dopt_CoreToDo dflags
+ let core_todos = dopt_CoreToDo dflags
+ let pkg_rule_base = pcs_rules pcs -- Rule-base accumulated from imported packages
+
us <- mkSplitUniqSupply 's'
let (cp_us, ru_us) = splitUniqSupply us
-- COMPUTE THE RULE BASE TO USE
- (rule_base, binds1, orphan_rules)
+ (rule_base, local_rule_ids, orphan_rules, rule_rhs_fvs)
<- prepareRules dflags pkg_rule_base hst ru_us binds rules
+ -- PREPARE THE BINDINGS
+ let binds1 = updateBinders local_rule_ids rule_rhs_fvs is_exported binds
-- DO THE BUSINESS
(stats, processed_binds)
return (processed_binds, orphan_rules)
+simplifyExpr :: DynFlags -- includes spec of what core-to-core passes to do
+ -> PersistentCompilerState
+ -> HomeSymbolTable
+ -> CoreExpr
+ -> IO CoreExpr
+-- simplifyExpr is called by the driver to simplify an
+-- expression typed in at the interactive prompt
+simplifyExpr dflags pcs hst expr
+ = do {
+ ; showPass dflags "Simplify"
+
+ ; us <- mkSplitUniqSupply 's'
+
+ ; let (expr', _counts) = initSmpl dflags sw_chkr us emptyVarSet black_list_nothing
+ (simplExprGently expr)
+
+ ; dumpIfSet_dyn dflags Opt_D_dump_simpl "Simplified expression"
+ (pprCoreExpr expr')
+
+ ; return expr'
+ }
+ where
+ sw_chkr any = SwBool False -- A bit bogus
+ black_list_nothing v = False -- Black list nothing
+
+
doCorePasses :: DynFlags
-> RuleBase -- the main rule base
-> SimplCount -- simplifier stats
= _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)
doCorePass dfs rb us binds CoreDoCPResult
= _scc_ "CPResult" noStats dfs (cprAnalyse dfs binds)
doCorePass dfs rb us binds CoreDoPrintCore
\begin{code}
prepareRules :: DynFlags -> PackageRuleBase -> HomeSymbolTable
-> UniqSupply
- -> [CoreBind] -> [IdCoreRule] -- Local bindings and rules
- -> IO (RuleBase, -- Full rule base
- [CoreBind], -- Bindings augmented with rules
- [IdCoreRule]) -- Orphan rules
+ -> [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 hst us binds rules
= do { let (better_rules,_) = initSmpl dflags sw_chkr us local_ids black_list_all
; dumpIfSet_dyn dflags Opt_D_dump_rules "Transformation rules"
(vcat (map pprIdCoreRule better_rules))
- ; let (local_id_rules, orphan_rules) = partition ((`elemVarSet` local_ids) . fst) better_rules
- (binds1, local_rule_fvs) = addRulesToBinds binds local_id_rules
- imp_rule_base = foldl add_rules pkg_rule_base (moduleEnvElts hst)
- rule_base = extendRuleBaseList imp_rule_base orphan_rules
- final_rule_base = addRuleBaseFVs rule_base local_rule_fvs
+ ; let (local_rules, orphan_rules) = partition (isLocalId . fst) better_rules
+ 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 hst)
+ 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
-
- ; return (final_rule_base, binds1, orphan_rules)
+ ; return (final_rule_base, local_rule_ids, orphan_rules, rule_rhs_fvs)
}
where
sw_chkr any = SwBool False -- A bit bogus
-- simpVar fails if it isn't right, and it might conceiveably matter
local_ids = foldr (unionVarSet . mkVarSet . bindersOf) emptyVarSet binds
-addRulesToBinds :: [CoreBind] -> [(Id,CoreRule)] -> ([CoreBind], IdSet)
+
+updateBinders :: IdSet -- Locally defined ids with their Rules attached
+ -> IdSet -- Ids free in the RHS of local rules
+ -> IsExported
+ -> [CoreBind] -> [CoreBind]
-- A horrible function
- -- Attach the rules for each locally-defined Id to that Id.
- -- - This 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
- --
- -- Both the LHS and RHS Ids are marked 'no-discard'.
- -- This 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.
-
-addRulesToBinds binds local_rules
- = (map zap_bind binds, rule_lhs_fvs)
+-- 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 mentoined in the RHS of a rule
+--
+-- 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 rule_ids rule_rhs_fvs is_exported binds
+ = map update_bndrs binds
where
- -- rule_fvs is the set of all variables mentioned in this module's rules
- rule_fvs = unionVarSets [ ruleSomeFreeVars isId rule | (_,rule) <- local_rules ]
-
- rule_base = extendRuleBaseList emptyRuleBase local_rules
- rule_lhs_fvs = ruleBaseFVs rule_base
- rule_ids = ruleBaseIds rule_base
-
- zap_bind (NonRec b r) = NonRec (zap_bndr b) r
- zap_bind (Rec prs) = Rec [(zap_bndr b, r) | (b,r) <- prs]
-
- zap_bndr bndr = case lookupVarSet rule_ids bndr of
- Just bndr' -> setIdNoDiscard bndr'
- Nothing | bndr `elemVarSet` rule_fvs -> setIdNoDiscard bndr
- | otherwise -> bndr
+ 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
+ | is_exported (idName bndr)
+ || bndr `elemVarSet` rule_rhs_fvs = setIdNoDiscard bndr'
+ | otherwise = bndr'
+ where
+ bndr' = lookupVarSet rule_ids bndr `orElse` bndr
\end{code}
= returnSmpl rule
simplRule rule@(id, Rule name bndrs args rhs)
= simplBinders bndrs $ \ bndrs' ->
- mapSmpl simpl_arg args `thenSmpl` \ args' ->
- simplExpr rhs `thenSmpl` \ rhs' ->
+ mapSmpl simplExprGently args `thenSmpl` \ args' ->
+ simplExprGently rhs `thenSmpl` \ rhs' ->
returnSmpl (id, Rule name bndrs' args' rhs')
-simpl_arg e
--- I've seen rules in which a LHS like
+-- It's important that simplExprGently does eta reduction.
+-- For example, in a rule like:
-- augment g (build h)
--- turns into
+-- we do not want to get
-- augment (\a. g a) (build h)
--- So it's a help to eta-reduce the args as we simplify them.
--- Otherwise we don't match when given an argument like
+-- otherwise we don't match when given an argument like
-- (\a. h a a)
- = simplExpr e `thenSmpl` \ e' ->
- returnSmpl (etaReduceExpr e')
+--
+-- The simplifier does indeed do eta reduction (it's in
+-- Simplify.completeLam) but only if -O is on.
+\end{code}
+
+\begin{code}
+simplExprGently :: 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
+simplExprGently expr
+ = simplExpr (occurAnalyseGlobalExpr expr) `thenSmpl` \ expr1 ->
+ simplExpr (occurAnalyseGlobalExpr expr1)
\end{code}
text "",
pprSimplCount counts_out]);
- endPass dflags "Simplify"
- (dopt Opt_D_verbose_core2core dflags
- && not (dopt Opt_D_dump_simpl_iterations dflags))
- binds' ;
+ endPass dflags "Simplify" Opt_D_verbose_core2core binds';
return (counts_out, binds')
}
++ " out of " ++ show max_iterations)
(pprSimplCount counts') ;
- if dopt Opt_D_dump_simpl_iterations dflags then
- endPass dflags
- ("Simplifier iteration " ++ show iteration_no ++ " result")
- (dopt Opt_D_verbose_core2core dflags)
- binds'
- else
- return [] ;
+ endPass dflags
+ ("Simplifier iteration " ++ show iteration_no ++ " result")
+ Opt_D_dump_simpl_iterations
+ binds' ;
-- Stop if we've run out of iterations
if iteration_no == max_iterations then
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