content: {-# LANGUAGE TypeSynonymInstances #-}
  {-# OPTIONS_GHC -fno-warn-orphans #-}
  
  {- BlockId module should probably go away completely, being superseded by Label -}
  module GHC.Cmm.BlockId
    ( BlockId, mkBlockId -- ToDo: BlockId should be abstract, but it isn't yet
    , newBlockId
    , blockLbl, infoTblLbl
    ) where
  
  import GHC.Prelude
  
  import GHC.Cmm.CLabel
  import GHC.Data.FastString
  import GHC.Types.Id.Info
  import GHC.Types.Name
  import GHC.Types.Unique
  import qualified GHC.Types.Unique.DSM as DSM
  
  import GHC.Cmm.Dataflow.Label (Label, mkHooplLabel)
  
  ----------------------------------------------------------------
  --- Block Ids, their environments, and their sets
  
  {- Note [Unique BlockId]
  ~~~~~~~~~~~~~~~~~~~~~~~~
  Although a 'BlockId' is a local label, for reasons of implementation,
  'BlockId's must be unique within an entire compilation unit.  The reason
  is that each local label is mapped to an assembly-language label, and in
  most assembly languages allow, a label is visible throughout the entire
  compilation unit in which it appears.
  -}
  
  type BlockId = Label
  
  mkBlockId :: Unique -> BlockId
  mkBlockId unique = mkHooplLabel $ getKey unique
  
  -- If the monad unique instance uses a deterministic unique supply, this will
  -- give you a deterministic unique. Otherwise, it will not. Note that from Cmm
  -- onwards (after deterministic renaming in 'codeGen'), there should only exist
  -- deterministic block labels.
  newBlockId :: DSM.MonadGetUnique m => m BlockId
  newBlockId = mkBlockId <$> DSM.getUniqueM
  
  blockLbl :: BlockId -> CLabel
  blockLbl label = mkLocalBlockLabel (getUnique label)
  
  infoTblLbl :: BlockId -> CLabel
  infoTblLbl label
    = mkBlockInfoTableLabel (mkFCallName (getUnique label) (fsLit "block")) NoCafRefs
  