\section[Desugar]{@deSugar@: the main function}
\begin{code}
-module Desugar ( deSugar ) where
+module Desugar ( deSugar, deSugarExpr ) where
#include "HsVersions.h"
-import CmdLineOpts ( DynFlags, DynFlag(..), dopt, opt_SccProfilingOn )
-import HsSyn ( MonoBinds, RuleDecl(..), RuleBndr(..),
- HsExpr(..), HsBinds(..), MonoBinds(..) )
-import TcHsSyn ( TypecheckedRuleDecl )
-import TcModule ( TcResults(..) )
+import DynFlags ( DynFlag(..), DynFlags(..), dopt, GhcMode(..) )
+import StaticFlags ( opt_SccProfilingOn )
+import DriverPhases ( isHsBoot )
+import HscTypes ( ModGuts(..), HscEnv(..),
+ Dependencies(..), ForeignStubs(..), TypeEnv, IsBootInterface )
+import HsSyn ( RuleDecl(..), RuleBndr(..), LHsExpr, LRuleDecl )
+import TcRnTypes ( TcGblEnv(..), ImportAvails(..) )
+import MkIface ( mkUsageInfo )
+import Id ( Id, setIdExported, idName )
+import Name ( Name, isExternalName, nameIsLocalOrFrom, nameOccName )
import CoreSyn
-import Rules ( ProtoCoreRule(..), pprProtoCoreRule )
-import Subst ( substExpr, mkSubst, mkInScopeSet )
+import PprCore ( pprRules, pprCoreExpr )
import DsMonad
-import DsExpr ( dsExpr )
-import DsBinds ( dsMonoBinds, AutoScc(..) )
+import DsExpr ( dsLExpr )
+import DsBinds ( dsTopLHsBinds, decomposeRuleLhs, AutoScc(..) )
import DsForeign ( dsForeigns )
import DsExpr () -- Forces DsExpr to be compiled; DsBinds only
-- depends on DsExpr.hi-boot.
-import Module ( Module )
-import VarEnv
+import Module ( Module, moduleEnvElts, delModuleEnv, moduleFS )
+import RdrName ( GlobalRdrEnv )
+import NameSet
import VarSet
-import Bag ( isEmptyBag )
-import CoreLint ( beginPass, endPass )
-import ErrUtils ( doIfSet, pprBagOfWarnings )
+import Bag ( Bag, isEmptyBag, emptyBag )
+import Rules ( roughTopNames )
+import CoreLint ( showPass, endPass )
+import CoreFVs ( ruleRhsFreeVars, exprsFreeNames )
+import Packages ( PackageState(thPackageId), PackageIdH(..) )
+import ErrUtils ( doIfSet, dumpIfSet_dyn, printBagOfWarnings,
+ errorsFound, WarnMsg )
+import ListSetOps ( insertList )
import Outputable
-import UniqSupply ( UniqSupply )
-import HscTypes ( HomeSymbolTable )
+import UniqSupply ( mkSplitUniqSupply )
+import SrcLoc ( Located(..) )
+import DATA_IOREF ( readIORef )
+import Maybes ( catMaybes )
+import FastString
+import Util ( sortLe )
\end{code}
%************************************************************************
%* *
%************************************************************************
-The only trick here is to get the @DsMonad@ stuff off to a good
-start.
-
\begin{code}
-deSugar :: DynFlags
- -> Module
- -> UniqSupply
- -> HomeSymbolTable
- -> TcResults
- -> IO ([CoreBind], [ProtoCoreRule], SDoc, SDoc, [CoreBndr])
-
-deSugar dflags mod_name us hst
- (TcResults {tc_env = global_val_env,
- tc_pcs = pcs,
- tc_binds = all_binds,
- tc_rules = rules,
- tc_fords = fo_decls})
- = do
- beginPass dflags "Desugar"
- -- Do desugaring
- let (result, ds_warns) =
- initDs dflags us (hst,pcs,global_val_env) mod_name
- (dsProgram mod_name all_binds rules fo_decls)
- (ds_binds, ds_rules, _, _, _) = result
-
- -- Display any warnings
- doIfSet (not (isEmptyBag ds_warns))
- (printErrs (pprBagOfWarnings ds_warns))
+deSugar :: HscEnv -> TcGblEnv -> IO (Bag WarnMsg, Maybe ModGuts)
+-- Can modify PCS by faulting in more declarations
- -- Lint result if necessary
- let do_dump_ds = dopt Opt_D_dump_ds dflags
- endPass dflags "Desugar" do_dump_ds ds_binds
+deSugar hsc_env
+ tcg_env@(TcGblEnv { tcg_mod = mod,
+ tcg_src = hsc_src,
+ tcg_type_env = type_env,
+ tcg_imports = imports,
+ tcg_home_mods = home_mods,
+ tcg_exports = exports,
+ tcg_dus = dus,
+ tcg_inst_uses = dfun_uses_var,
+ tcg_th_used = th_var,
+ tcg_keep = keep_var,
+ tcg_rdr_env = rdr_env,
+ tcg_fix_env = fix_env,
+ tcg_deprecs = deprecs,
+ tcg_binds = binds,
+ tcg_fords = fords,
+ tcg_rules = rules,
+ tcg_insts = insts })
+ = do { showPass dflags "Desugar"
- doIfSet do_dump_ds (printDump (ppr_ds_rules ds_rules))
+ -- Desugar the program
+ ; ((all_prs, ds_rules, ds_fords), warns)
+ <- case ghcMode (hsc_dflags hsc_env) of
+ JustTypecheck -> return (([], [], NoStubs), emptyBag)
+ _ -> initDs hsc_env mod rdr_env type_env $ do
+ { core_prs <- dsTopLHsBinds auto_scc binds
+ ; (ds_fords, foreign_prs) <- dsForeigns fords
+ ; let all_prs = foreign_prs ++ core_prs
+ local_bndrs = mkVarSet (map fst all_prs)
+ ; ds_rules <- mappM (dsRule mod local_bndrs) rules
+ ; return (all_prs, catMaybes ds_rules, ds_fords)
+ }
- return result
+ -- If warnings are considered errors, leave.
+ ; if errorsFound dflags (warns, emptyBag)
+ then return (warns, Nothing)
+ else do
-dsProgram mod_name all_binds rules fo_decls
- = dsMonoBinds auto_scc all_binds [] `thenDs` \ core_prs ->
- dsForeigns mod_name fo_decls `thenDs` \ (fe_binders, foreign_binds, h_code, c_code) ->
- let
- ds_binds = [Rec (foreign_binds ++ core_prs)]
+ { -- Add export flags to bindings
+ keep_alive <- readIORef keep_var
+ ; let final_prs = addExportFlags ghci_mode exports keep_alive
+ all_prs ds_rules
+ ds_binds = [Rec final_prs]
-- Notice that we put the whole lot in a big Rec, even the foreign binds
-- When compiling PrelFloat, which defines data Float = F# Float#
-- we want F# to be in scope in the foreign marshalling code!
-- You might think it doesn't matter, but the simplifier brings all top-level
-- things into the in-scope set before simplifying; so we get no unfolding for F#!
- local_binders = mkVarSet (bindersOfBinds ds_binds)
- in
- mapDs (dsRule local_binders) rules `thenDs` \ rules' ->
- returnDs (ds_binds, rules', h_code, c_code, fe_binders)
+ -- Lint result if necessary
+ ; endPass dflags "Desugar" Opt_D_dump_ds ds_binds
+
+ -- Dump output
+ ; doIfSet (dopt Opt_D_dump_ds dflags)
+ (printDump (ppr_ds_rules ds_rules))
+
+ ; dfun_uses <- readIORef dfun_uses_var -- What dfuns are used
+ ; th_used <- readIORef th_var -- Whether TH is used
+ ; let used_names = allUses dus `unionNameSets` dfun_uses
+ thPackage = thPackageId (pkgState dflags)
+ pkgs | ExtPackage th_id <- thPackage, th_used
+ = insertList th_id (imp_dep_pkgs imports)
+ | otherwise
+ = imp_dep_pkgs imports
+
+ dep_mods = moduleEnvElts (delModuleEnv (imp_dep_mods imports) mod)
+ -- M.hi-boot can be in the imp_dep_mods, but we must remove
+ -- it before recording the modules on which this one depends!
+ -- (We want to retain M.hi-boot in imp_dep_mods so that
+ -- loadHiBootInterface can see if M's direct imports depend
+ -- on M.hi-boot, and hence that we should do the hi-boot consistency
+ -- check.)
+
+ dir_imp_mods = imp_mods imports
+
+ ; usages <- mkUsageInfo hsc_env home_mods dir_imp_mods dep_mods used_names
+
+ ; let
+ -- Modules don't compare lexicographically usually,
+ -- but we want them to do so here.
+ le_mod :: Module -> Module -> Bool
+ le_mod m1 m2 = moduleFS m1 <= moduleFS m2
+ le_dep_mod :: (Module, IsBootInterface) -> (Module, IsBootInterface) -> Bool
+ le_dep_mod (m1,_) (m2,_) = m1 `le_mod` m2
+
+ deps = Deps { dep_mods = sortLe le_dep_mod dep_mods,
+ dep_pkgs = sortLe (<=) pkgs,
+ dep_orphs = sortLe le_mod (imp_orphs imports) }
+ -- sort to get into canonical order
+
+ mod_guts = ModGuts {
+ mg_module = mod,
+ mg_boot = isHsBoot hsc_src,
+ mg_exports = exports,
+ mg_deps = deps,
+ mg_home_mods = home_mods,
+ mg_usages = usages,
+ mg_dir_imps = [m | (m,_,_) <- moduleEnvElts dir_imp_mods],
+ mg_rdr_env = rdr_env,
+ mg_fix_env = fix_env,
+ mg_deprecs = deprecs,
+ mg_types = type_env,
+ mg_insts = insts,
+ mg_rules = ds_rules,
+ mg_binds = ds_binds,
+ mg_foreign = ds_fords }
+
+ ; return (warns, Just mod_guts)
+ }}
+
where
+ dflags = hsc_dflags hsc_env
+ ghci_mode = ghcMode (hsc_dflags hsc_env)
auto_scc | opt_SccProfilingOn = TopLevel
| otherwise = NoSccs
+deSugarExpr :: HscEnv
+ -> Module -> GlobalRdrEnv -> TypeEnv
+ -> LHsExpr Id
+ -> IO CoreExpr
+deSugarExpr hsc_env this_mod rdr_env type_env tc_expr
+ = do { showPass dflags "Desugar"
+ ; us <- mkSplitUniqSupply 'd'
+
+ -- Do desugaring
+ ; (core_expr, ds_warns) <- initDs hsc_env this_mod rdr_env type_env $
+ dsLExpr tc_expr
+
+ -- Display any warnings
+ -- Note: if -Werror is used, we don't signal an error here.
+ ; doIfSet (not (isEmptyBag ds_warns))
+ (printBagOfWarnings dflags ds_warns)
+
+ -- Dump output
+ ; dumpIfSet_dyn dflags Opt_D_dump_ds "Desugared" (pprCoreExpr core_expr)
+
+ ; return core_expr
+ }
+ where
+ dflags = hsc_dflags hsc_env
+
+
+-- addExportFlags
+-- Set the no-discard flag if either
+-- a) the Id is exported
+-- b) it's mentioned in the RHS of an orphan rule
+-- c) it's in the keep-alive set
+--
+-- 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.
+
+-- 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.
+
+addExportFlags ghci_mode exports keep_alive prs rules
+ = [(add_export bndr, rhs) | (bndr,rhs) <- prs]
+ where
+ add_export bndr
+ | dont_discard bndr = setIdExported bndr
+ | otherwise = bndr
+
+ orph_rhs_fvs = unionVarSets [ ruleRhsFreeVars rule
+ | rule <- rules,
+ not (isLocalRule rule) ]
+ -- A non-local rule keeps alive the free vars of its right-hand side.
+ -- (A "non-local" is one whose head function is not locally defined.)
+ -- Local rules are (later, after gentle simplification)
+ -- attached to the Id, and that keeps the rhs free vars alive.
+
+ dont_discard bndr = is_exported name
+ || name `elemNameSet` keep_alive
+ || bndr `elemVarSet` orph_rhs_fvs
+ where
+ name = idName bndr
+
+ -- 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` exports)
+
ppr_ds_rules [] = empty
ppr_ds_rules rules
= text "" $$ text "-------------- DESUGARED RULES -----------------" $$
- vcat (map pprProtoCoreRule rules)
+ pprRules rules
\end{code}
+
%************************************************************************
%* *
%* Desugaring transformation rules
%************************************************************************
\begin{code}
-dsRule :: IdSet -> TypecheckedRuleDecl -> DsM ProtoCoreRule
-dsRule in_scope (IfaceRuleOut fn rule)
- = returnDs (ProtoCoreRule False {- non-local -} fn rule)
-
-dsRule in_scope (HsRule name sig_tvs vars lhs rhs loc)
- = putSrcLocDs loc $
- ds_lhs all_vars lhs `thenDs` \ (fn, args) ->
- dsExpr rhs `thenDs` \ core_rhs ->
- returnDs (ProtoCoreRule True {- local -} fn
- (Rule name tpl_vars args core_rhs))
- where
- tpl_vars = sig_tvs ++ [var | RuleBndr var <- vars]
- all_vars = mkInScopeSet (in_scope `unionVarSet` mkVarSet tpl_vars)
-
-ds_lhs all_vars lhs
- = let
- (dict_binds, body) = case lhs of
- (HsLet (MonoBind dict_binds _ _) body) -> (dict_binds, body)
- other -> (EmptyMonoBinds, lhs)
- in
- ds_dict_binds dict_binds `thenDs` \ dict_binds' ->
- dsExpr body `thenDs` \ body' ->
+dsRule :: Module -> IdSet -> LRuleDecl Id -> DsM (Maybe CoreRule)
+dsRule mod in_scope (L loc (HsRule name act vars lhs tv_lhs rhs fv_rhs))
+ = putSrcSpanDs loc $
+ do { let bndrs = [var | RuleBndr (L _ var) <- vars]
+ ; lhs' <- dsLExpr lhs
+ ; rhs' <- dsLExpr rhs
+ ; case decomposeRuleLhs bndrs lhs' of {
+ Nothing -> do { dsWarn msg; return Nothing } ;
+ Just (bndrs', fn_id, args) -> do
+
-- Substitute the dict bindings eagerly,
-- and take the body apart into a (f args) form
- let
- subst_env = mkSubstEnv [id | (id,rhs) <- dict_binds']
- [ContEx subst_env rhs | (id,rhs) <- dict_binds']
- -- Note recursion here... substitution won't terminate
- -- if there is genuine recursion... which there isn't
-
- subst = mkSubst all_vars subst_env
- body'' = substExpr subst body'
- in
-
- -- Now unpack the resulting body
- let
- pair = case collectArgs body'' of
- (Var fn, args) -> (fn, args)
- other -> pprPanic "dsRule" (ppr lhs)
- in
- returnDs pair
-
-ds_dict_binds EmptyMonoBinds = returnDs []
-ds_dict_binds (AndMonoBinds b1 b2) = ds_dict_binds b1 `thenDs` \ env1 ->
- ds_dict_binds b2 `thenDs` \ env2 ->
- returnDs (env1 ++ env2)
-ds_dict_binds (VarMonoBind id rhs) = dsExpr rhs `thenDs` \ rhs' ->
- returnDs [(id,rhs')]
+ { let local_rule = nameIsLocalOrFrom mod fn_name
+ -- NB we can't use isLocalId in the orphan test,
+ -- because isLocalId isn't true of class methods
+ fn_name = idName fn_id
+ lhs_names = fn_name : nameSetToList (exprsFreeNames args)
+ -- No need to delete bndrs, because
+ -- exprsFreeNames finds only External names
+ orph = case filter (nameIsLocalOrFrom mod) lhs_names of
+ (n:ns) -> Just (nameOccName n)
+ [] -> Nothing
+
+ rule = Rule { ru_name = name, ru_fn = fn_name, ru_act = act,
+ ru_bndrs = bndrs', ru_args = args, ru_rhs = rhs',
+ ru_rough = roughTopNames args,
+ ru_local = local_rule, ru_orph = orph }
+ ; return (Just rule)
+ } } }
+ where
+ msg = hang (ptext SLIT("RULE left-hand side too complicated to desugar; ignored"))
+ 2 (ppr lhs)
\end{code}
projects / ghc-hetmet.git / blobdiff