X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=ghc%2Fcompiler%2FsimplCore%2FSimplCore.lhs;h=17b322b9b61d6a3c31fb464b057982a8dc7b49f2;hb=7f82f577d34b201b7345794ece8b9dbb680a0257;hp=723b776090d90cb0dd4c20c63131bc488cee98f1;hpb=243dedb8741d13162fe944ebf2adace921e0108d;p=ghc-hetmet.git diff --git a/ghc/compiler/simplCore/SimplCore.lhs b/ghc/compiler/simplCore/SimplCore.lhs index 723b776..17b322b 100644 --- a/ghc/compiler/simplCore/SimplCore.lhs +++ b/ghc/compiler/simplCore/SimplCore.lhs @@ -4,46 +4,57 @@ \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 +import CmdLineOpts ( CoreToDo(..), SimplifierSwitch(..), + SimplifierMode(..), DynFlags, DynFlag(..), dopt, + dopt_CoreToDo ) -import CoreLint ( beginPass, endPass ) import CoreSyn -import CoreFVs ( ruleSomeFreeVars ) -import HscTypes ( PackageRuleBase, HomeSymbolTable, ModDetails(..) ) +import CoreFVs ( ruleRhsFreeVars ) +import HscTypes ( PersistentCompilerState(..), ExternalPackageState(..), + HscEnv(..), GhciMode(..), + ModGuts(..), ModGuts, Avails, availsToNameSet, + PackageRuleBase, HomePackageTable, ModDetails(..), + HomeModInfo(..) + ) import CSE ( cseProgram ) -import Rules ( RuleBase, emptyRuleBase, ruleBaseFVs, ruleBaseIds, extendRuleBaseList, addRuleBaseFVs ) +import Rules ( RuleBase, emptyRuleBase, ruleBaseFVs, ruleBaseIds, + extendRuleBaseList, addRuleBaseFVs, pprRuleBase, + ruleCheckProgram ) import Module ( moduleEnvElts ) -import CoreUnfold -import PprCore ( pprCoreBindings, pprIdCoreRule ) -import OccurAnal ( occurAnalyseBinds ) -import CoreUtils ( etaReduceExpr, coreBindsSize ) +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 ErrUtils ( dumpIfSet, dumpIfSet_dyn ) +import ErrUtils ( dumpIfSet, dumpIfSet_dyn, showPass ) +import CoreLint ( endPass ) import FloatIn ( floatInwards ) import FloatOut ( floatOutwards ) -import Id ( Id, isDataConWrapId, setIdNoDiscard ) +import Id ( idName, setIdLocalExported ) import VarSet import LiberateCase ( liberateCase ) import SAT ( doStaticArgs ) import Specialise ( specProgram) -import UsageSPInf ( doUsageSPInf ) -import StrictAnal ( saBinds ) +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 +import Maybes ( orElse ) import List ( partition ) \end{code} @@ -54,23 +65,32 @@ import List ( partition ) %************************************************************************ \begin{code} -core2core :: DynFlags - -> PackageRuleBase -- Rule-base accumulated from imported packages - -> HomeSymbolTable - -> [CoreToDo] -- Spec of what core-to-core passes to do - -> [CoreBind] -- Binds in - -> [IdCoreRule] -- Rules in - -> IO ([CoreBind], [IdCoreRule]) -- binds, local orphan rules out - -core2core dflags pkg_rule_base hst core_todos binds rules +core2core :: HscEnv + -> PersistentCompilerState + -> ModGuts + -> IO ModGuts + +core2core hsc_env pcs + 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 + pkg_rule_base = eps_rule_base (pcs_EPS 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) - <- prepareRules dflags pkg_rule_base hst ru_us binds rules + (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 -- DO THE BUSINESS (stats, processed_binds) @@ -83,7 +103,28 @@ core2core dflags pkg_rule_base hst core_todos binds rules -- 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 (processed_binds, orphan_rules) + return (mod_impl { mg_binds = processed_binds, mg_rules = orphan_rules}) + + +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" + + ; us <- mkSplitUniqSupply 's' + + ; let env = emptySimplEnv SimplGently [] emptyVarSet + (expr', _counts) = initSmpl dflags us (simplExprGently env expr) + + ; dumpIfSet_dyn dflags Opt_D_dump_simpl "Simplified expression" + (pprCoreExpr expr') + + ; return expr' + } doCorePasses :: DynFlags @@ -105,8 +146,8 @@ doCorePasses dflags rb stats us binds (to_do : to_dos) doCorePasses dflags rb (stats `plusSimplCount` stats1) us2 binds1 to_dos -doCorePass dfs rb us binds (CoreDoSimplify sw_chkr) - = _scc_ "Simplify" simplifyPgm dfs rb sw_chkr us binds +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 @@ -118,26 +159,44 @@ doCorePass dfs rb us binds (CoreDoFloatOutwards f) doCorePass dfs rb us binds CoreDoStaticArgs = _scc_ "StaticArgs" noStats dfs (doStaticArgs us binds) doCorePass dfs rb us binds CoreDoStrictness - = _scc_ "Stranal" noStats dfs (saBinds dfs binds) + = _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 CoreDoCPResult - = _scc_ "CPResult" noStats dfs (cprAnalyse dfs 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 CoreDoUSPInf - = _scc_ "CoreUsageSPInf" noStats dfs (doUsageSPInf dfs us 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) } + \end{code} @@ -157,78 +216,111 @@ noStats dfs thing = do { binds <- thing; return (zeroSimplCount dfs, binds) } -- so that the opportunity to apply the rule isn't lost too soon \begin{code} -prepareRules :: DynFlags -> PackageRuleBase -> HomeSymbolTable +prepareRules :: DynFlags -> PackageRuleBase -> HomePackageTable -> UniqSupply - -> [CoreBind] -> [IdCoreRule] -- Local bindings and rules - -> IO (RuleBase, -- Full rule base - [CoreBind], -- Bindings augmented with rules - [IdCoreRule]) -- Orphan rules - -prepareRules dflags pkg_rule_base hst us binds rules - = do { let (better_rules,_) = initSmpl dflags sw_chkr us local_ids black_list_all - (mapSmpl simplRule 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 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 (map pprIdCoreRule better_rules)) + (vcat [text "Local rules", pprRuleBase local_rule_base, + text "", + text "Imported rules", pprRuleBase final_rule_base]) - ; 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 - -- 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 - black_list_all v = not (isDataConWrapId v) - -- This stops all inlining except the - -- wrappers for data constructors - - add_rules rule_base mds = extendRuleBaseList rule_base (md_rules mds) + add_rules rule_base mod_info = extendRuleBaseList rule_base (md_rules (hm_details mod_info)) -- Boringly, we need to gather the in-scope set. - -- Typically this thunk won't even be forced, but the test in - -- 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 :: 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 - -- 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 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 - -- 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] + 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) - zap_bndr bndr = case lookupVarSet rule_ids bndr of - Just bndr' -> setIdNoDiscard bndr' - Nothing | bndr `elemVarSet` rule_fvs -> setIdNoDiscard bndr - | otherwise -> bndr + export_fvs = availsToNameSet exports \end{code} @@ -239,24 +331,42 @@ which without simplification looked like: This doesn't match unless you do eta reduction on the build argument. \begin{code} -simplRule rule@(id, BuiltinRule _) +simplRule env rule@(id, BuiltinRule _ _) = returnSmpl rule -simplRule rule@(id, Rule name bndrs args rhs) - = simplBinders bndrs $ \ bndrs' -> - mapSmpl simpl_arg args `thenSmpl` \ args' -> - simplExpr rhs `thenSmpl` \ rhs' -> - returnSmpl (id, Rule name bndrs' args' rhs') - -simpl_arg e --- I've seen rules in which a LHS like +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) --- 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 :: 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} @@ -294,7 +404,7 @@ glomBinds :: DynFlags -> [CoreBind] -> IO [CoreBind] -- analyser as free in f. glomBinds dflags binds - = do { beginPass dflags "GlomBinds" ; + = do { showPass dflags "GlomBinds" ; let { recd_binds = [Rec (flattenBinds binds)] } ; return recd_binds } -- Not much point in printing the result... @@ -311,15 +421,16 @@ glomBinds dflags binds \begin{code} simplifyPgm :: DynFlags -> RuleBase - -> (SimplifierSwitch -> SwitchResult) + -> SimplifierMode + -> [SimplifierSwitch] -> UniqSupply -> [CoreBind] -- Input -> IO (SimplCount, [CoreBind]) -- New bindings simplifyPgm dflags rule_base - sw_chkr us binds + mode switches us binds = do { - beginPass dflags "Simplify"; + showPass dflags "Simplify"; (termination_msg, it_count, counts_out, binds') <- iteration us 1 (zeroSimplCount dflags) binds; @@ -331,20 +442,38 @@ simplifyPgm dflags rule_base 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') } where - max_iterations = getSimplIntSwitch sw_chkr MaxSimplifierIterations - black_list_fn = blackListed rule_lhs_fvs (intSwitchSet sw_chkr SimplInlinePhase) + phase_info = case mode of + SimplGently -> "gentle" + SimplPhase n -> show n + imported_rule_ids = ruleBaseIds rule_base - rule_lhs_fvs = ruleBaseFVs 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 @@ -363,18 +492,21 @@ simplifyPgm dflags rule_base -- t = initSmpl ... -- counts' = snd t -- in - -- case t of {(_,counts') -> if counts'=0 then ... + -- case t of {(_,counts') -> if counts'=0 then ... } -- So the conditional didn't force counts', because the -- selection got duplicated. Sigh! - case initSmpl dflags sw_chkr us1 imported_rule_ids black_list_fn - (simplTopBinds tagged_binds) - of { (binds', counts') -> do { + 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' } ; + let { all_counts = counts `plusSimplCount` counts' ; + herald = "Simplifier phase " ++ phase_info ++ + ", iteration " ++ show iteration_no ++ + " out of " ++ show max_iterations + } ; -- Stop if nothing happened; don't dump output if isZeroSimplCount counts' then @@ -382,36 +514,13 @@ simplifyPgm dflags rule_base else do { -- Dump the result of this iteration - dumpIfSet_dyn dflags Opt_D_dump_simpl_iterations - ("Simplifier iteration " ++ show iteration_no - ++ " 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 [] ; - - -- Stop if we've run out of iterations - if iteration_no == max_iterations then - do { -#ifdef DEBUG - if max_iterations > 2 then - hPutStr stderr ("NOTE: Simplifier still going after " ++ - show max_iterations ++ - " iterations; bailing out.\n") - else -#endif - return (); + dumpIfSet_dyn dflags Opt_D_dump_simpl_iterations herald + (pprSimplCount counts') ; - return ("Simplifier baled out", iteration_no, all_counts, binds') - } + endPass dflags herald Opt_D_dump_simpl_iterations binds' ; - -- Else loop - else iteration us2 (iteration_no + 1) all_counts binds' + -- Loop + iteration us2 (iteration_no + 1) all_counts binds' } } } } where (us1, us2) = splitUniqSupply us