\section[Desugar]{@deSugar@: the main function}
\begin{code}
-module Desugar ( deSugar ) where
+module Desugar ( deSugar, deSugarExpr ) where
#include "HsVersions.h"
-import CmdLineOpts ( opt_D_dump_ds )
-import HsSyn ( MonoBinds )
-import TcHsSyn ( TypecheckedMonoBinds, TypecheckedForeignDecl )
+import CmdLineOpts ( DynFlag(..), DynFlags(..), dopt, opt_SccProfilingOn )
+import HscTypes ( ModGuts(..), ModGuts, HscEnv(..), GhciMode(..),
+ Dependencies(..), TypeEnv, IsBootInterface, unQualInScope )
+import HsSyn ( RuleDecl(..), RuleBndr(..), HsExpr(..), LHsExpr,
+ HsBindGroup(..), LRuleDecl, HsBind(..) )
+import TcRnTypes ( TcGblEnv(..), ImportAvails(..) )
+import MkIface ( mkUsageInfo )
+import Id ( Id, setIdLocalExported, idName, idIsFrom, isLocalId )
+import Name ( Name, isExternalName )
import CoreSyn
+import PprCore ( pprIdRules, pprCoreExpr )
+import Subst ( SubstResult(..), substExpr, mkSubst, extendIdSubstList )
import DsMonad
-import DsBinds ( dsMonoBinds )
+import DsExpr ( dsLExpr )
+import DsBinds ( dsHsBinds, AutoScc(..) )
import DsForeign ( dsForeigns )
-import DsUtils
import DsExpr () -- Forces DsExpr to be compiled; DsBinds only
-- depends on DsExpr.hi-boot.
-
-import Bag ( isEmptyBag )
-import BasicTypes ( Module )
-import CmdLineOpts ( opt_SccGroup, opt_SccProfilingOn )
-import CoreLint ( beginPass, endPass )
-import ErrUtils ( doIfSet )
+import Module ( Module, moduleEnvElts, delModuleEnv, moduleFS )
+import Id ( Id )
+import RdrName ( GlobalRdrEnv )
+import NameSet
+import VarEnv
+import VarSet
+import Bag ( Bag, isEmptyBag, mapBag, emptyBag, bagToList )
+import CoreLint ( showPass, endPass )
+import CoreFVs ( ruleRhsFreeVars )
+import Packages ( PackageState(thPackageId) )
+import ErrUtils ( doIfSet, dumpIfSet_dyn, pprBagOfWarnings,
+ mkWarnMsg, errorsFound, WarnMsg )
+import ListSetOps ( insertList )
import Outputable
-import UniqSupply ( splitUniqSupply, UniqSupply )
+import UniqSupply ( mkSplitUniqSupply )
+import SrcLoc ( Located(..), SrcSpan, unLoc )
+import DATA_IOREF ( readIORef )
+import FastString
+import Util ( sortLe )
\end{code}
-The only trick here is to get the @DsMonad@ stuff off to a good
-start.
+%************************************************************************
+%* *
+%* The main function: deSugar
+%* *
+%************************************************************************
\begin{code}
-deSugar :: UniqSupply -- name supply
- -> GlobalValueEnv -- value env
- -> Module -- module name
- -> TypecheckedMonoBinds
- -> [TypecheckedForeignDecl]
- -> IO ([CoreBind], SDoc, SDoc) -- output
-
-deSugar us global_val_env mod_name all_binds fo_decls = do
- beginPass "Desugar"
+deSugar :: HscEnv -> TcGblEnv -> IO (Bag WarnMsg, Maybe ModGuts)
+-- Can modify PCS by faulting in more declarations
+
+deSugar hsc_env
+ tcg_env@(TcGblEnv { tcg_mod = mod,
+ tcg_type_env = type_env,
+ tcg_imports = imports,
+ 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"
+
+ -- Desugar the program
+ ; ((all_prs, ds_rules, ds_fords), warns)
+ <- initDs hsc_env mod rdr_env type_env $ do
+ { core_prs <- dsHsBinds 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, ds_rules, ds_fords) }
+
+
+
+ -- If warnings are considered errors, leave.
+ ; if errorsFound dflags (warns, emptyBag)
+ then return (warns, Nothing)
+ else do
+
+ { -- 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#!
+
+ -- 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 | Just 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 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_exports = exports,
+ mg_deps = deps,
+ 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 = hsc_mode 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
- let (core_prs, ds_warns) = initDs us1 global_val_env module_and_group
- (dsMonoBinds opt_SccProfilingOn all_binds [])
- ds_binds' = [Rec core_prs]
+ ; (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))
+ (printErrs (pprBagOfWarnings 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.
- ((fi_binds, fe_binds, h_code, c_code), ds_warns2) =
- initDs us3 global_val_env module_and_group (dsForeigns fo_decls)
+addExportFlags ghci_mode exports keep_alive prs rules
+ = [(add_export bndr, rhs) | (bndr,rhs) <- prs]
+ where
+ add_export bndr
+ | isLocalId bndr && dont_discard bndr = setIdLocalExported bndr
+ -- The isLocalId check is to avoid fiddling with
+ -- locally-defined Ids like data cons and class ops
+ -- which are "born" as GlobalIds
+ | otherwise = bndr
+
+ orph_rhs_fvs = unionVarSets [ ruleRhsFreeVars rule
+ | IdCoreRule _ is_orphan_rule rule <- rules,
+ is_orphan_rule ]
+ -- An orphan rule keeps alive the free vars of its right-hand side.
+ -- Non-orphan 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
- ds_binds = fi_binds ++ ds_binds' ++ fe_binds
+ -- 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 "" $$ text "-------------- DESUGARED RULES -----------------" $$
+ pprIdRules rules
+\end{code}
- -- Display any warnings
- doIfSet (not (isEmptyBag ds_warns))
- (printErrs (pprDsWarnings ds_warns))
- -- Lint result if necessary
- endPass "Desugar" opt_D_dump_ds ds_binds
- return (ds_binds, h_code, c_code)
+
+%************************************************************************
+%* *
+%* Desugaring transformation rules
+%* *
+%************************************************************************
+
+\begin{code}
+dsRule :: Module -> IdSet -> LRuleDecl Id -> DsM IdCoreRule
+dsRule mod in_scope (L loc (HsRule name act vars lhs rhs))
+ = putSrcSpanDs loc $
+ ds_lhs all_vars lhs `thenDs` \ (fn, args) ->
+ dsLExpr rhs `thenDs` \ core_rhs ->
+ returnDs (IdCoreRule fn (is_orphan fn) (Rule name act tpl_vars args core_rhs))
where
- (us1, us2) = splitUniqSupply us
- (us3, us4) = splitUniqSupply us2
+ tpl_vars = [var | RuleBndr (L _ var) <- vars]
+ all_vars = mkInScopeSet (extendVarSetList in_scope tpl_vars)
+ is_orphan id = not (idIsFrom mod id)
+ -- NB we can't use isLocalId in the orphan test,
+ -- because isLocalId isn't true of class methods
+
+ds_lhs all_vars lhs
+ = let
+ (dict_binds, body) =
+ case unLoc lhs of
+ (HsLet [HsBindGroup dict_binds _ _] body) -> (dict_binds, body)
+ other -> (emptyBag, lhs)
+ in
+ mappM ds_dict_bind (bagToList dict_binds) `thenDs` \ dict_binds' ->
+ dsLExpr body `thenDs` \ body' ->
- module_and_group = (mod_name, grp_name)
- grp_name = case opt_SccGroup of
- Just xx -> _PK_ xx
- Nothing -> mod_name -- default: module name
+ -- Substitute the dict bindings eagerly,
+ -- and take the body apart into a (f args) form
+ let
+ subst = extendIdSubstList (mkSubst all_vars) pairs
+ pairs = [(id, ContEx subst rhs) | (id,rhs) <- dict_binds']
+ -- Note recursion here... substitution won't terminate
+ -- if there is genuine recursion... which there isn't
+ 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_bind (L _ (VarBind id rhs)) =
+ dsLExpr rhs `thenDs` \ rhs' ->
+ returnDs (id,rhs')
\end{code}
projects / ghc-hetmet.git / blobdiff