    -- |
    -- Various utilities for forcing Core structures
    --
    -- It can often be useful to force various parts of the AST. This module
    -- provides a number of @seq@-like functions to accomplish this.

    module CoreSeq (
            -- * Utilities for forcing Core structures
            seqExpr, seqExprs, seqUnfolding, seqRules,
            megaSeqIdInfo, seqRuleInfo, seqBinds,
        ) where

    import GhcPrelude

    import CoreSyn
    import IdInfo
    import Demand( seqDemand, seqStrictSig )
    import BasicTypes( seqOccInfo )
    import VarSet( seqDVarSet )
    import Var( varType, tyVarKind )
    import Type( seqType, isTyVar )
    import Coercion( seqCo )
    import Id( Id, idInfo )

    -- | Evaluate all the fields of the 'IdInfo' that are generally demanded by the
    -- compiler
    megaSeqIdInfo :: IdInfo -> ()
    megaSeqIdInfo info
      = seqRuleInfo (ruleInfo info)                 `seq`

    -- Omitting this improves runtimes a little, presumably because
    -- some unfoldings are not calculated at all
    --    seqUnfolding (unfoldingInfo info)         `seq`

        seqDemand (demandInfo info)                 `seq`
        seqStrictSig (strictnessInfo info)          `seq`
        seqCaf (cafInfo info)                       `seq`
        seqOneShot (oneShotInfo info)               `seq`
        seqOccInfo (occInfo info)

    seqOneShot :: OneShotInfo -> ()
    seqOneShot l = l `seq` ()

    seqRuleInfo :: RuleInfo -> ()
    seqRuleInfo (RuleInfo rules fvs) = seqRules rules `seq` seqDVarSet fvs

    seqCaf :: CafInfo -> ()
    seqCaf c = c `seq` ()

    seqRules :: [CoreRule] -> ()
    seqRules [] = ()
    seqRules (Rule { ru_bndrs = bndrs, ru_args = args, ru_rhs = rhs } : rules)
      = seqBndrs bndrs `seq` seqExprs (rhs:args) `seq` seqRules rules
    seqRules (BuiltinRule {} : rules) = seqRules rules

    seqExpr :: CoreExpr -> ()
    seqExpr (Var v)         = v `seq` ()
    seqExpr (Lit lit)       = lit `seq` ()
    seqExpr (App f a)       = seqExpr f `seq` seqExpr a
    seqExpr (Lam b e)       = seqBndr b `seq` seqExpr e
    seqExpr (Let b e)       = seqBind b `seq` seqExpr e
    seqExpr (Case e b t as) = seqExpr e `seq` seqBndr b `seq` seqType t `seq` seqAlts as
    seqExpr (Cast e co)     = seqExpr e `seq` seqCo co
    seqExpr (Tick n e)      = seqTickish n `seq` seqExpr e
    seqExpr (Type t)        = seqType t
    seqExpr (Coercion co)   = seqCo co

    seqExprs :: [CoreExpr] -> ()
    seqExprs [] = ()
    seqExprs (e:es) = seqExpr e `seq` seqExprs es

    seqTickish :: Tickish Id -> ()
    seqTickish ProfNote{ profNoteCC = cc } = cc `seq` ()
    seqTickish HpcTick{} = ()
    seqTickish Breakpoint{ breakpointFVs = ids } = seqBndrs ids
    seqTickish SourceNote{} = ()

    seqBndr :: CoreBndr -> ()
    seqBndr b | isTyVar b = seqType (tyVarKind b)
              | otherwise = seqType (varType b)             `seq`
                            megaSeqIdInfo (idInfo b)

    seqBndrs :: [CoreBndr] -> ()
    seqBndrs [] = ()
    seqBndrs (b:bs) = seqBndr b `seq` seqBndrs bs

    seqBinds :: [Bind CoreBndr] -> ()
    seqBinds bs = foldr (seq . seqBind) () bs

    seqBind :: Bind CoreBndr -> ()
    seqBind (NonRec b e) = seqBndr b `seq` seqExpr e
    seqBind (Rec prs)    = seqPairs prs

    seqPairs :: [(CoreBndr, CoreExpr)] -> ()
    seqPairs [] = ()
    seqPairs ((b,e):prs) = seqBndr b `seq` seqExpr e `seq` seqPairs prs

    seqAlts :: [CoreAlt] -> ()
    seqAlts [] = ()
    seqAlts ((c,bs,e):alts) = c `seq` seqBndrs bs `seq` seqExpr e `seq` seqAlts alts

    seqUnfolding :: Unfolding -> ()
    seqUnfolding (CoreUnfolding { uf_tmpl = e, uf_is_top = top,
                    uf_is_value = b1, uf_is_work_free = b2,
                    uf_expandable = b3, uf_is_conlike = b4,
                    uf_guidance = g})
      = seqExpr e `seq` top `seq` b1 `seq` b2 `seq` b3 `seq` b4 `seq` seqGuidance g

    seqUnfolding _ = ()

    seqGuidance :: UnfoldingGuidance -> ()
    seqGuidance (UnfIfGoodArgs ns n b) = n `seq` sum ns `seq` b `seq` ()
    seqGuidance _                      = ()