content: {-# LANGUAGE LambdaCase #-}
  
  -----------------------------------------------------------------------------
  --
  -- Object-file symbols (called CLabel for historical reasons).
  --
  -- (c) The University of Glasgow 2004-2006
  --
  -----------------------------------------------------------------------------
  
  module GHC.Cmm.CLabel (
          CLabel, -- abstract type
          NeedExternDecl (..),
          ForeignLabelSource(..),
          DynamicLinkerLabelInfo(..),
          ConInfoTableLocation(..),
          getConInfoTableLocation,
  
          -- * Constructors
          mkClosureLabel,
          mkSRTLabel,
          mkInfoTableLabel,
          mkEntryLabel,
          mkRednCountsLabel,
          mkTagHitLabel,
          mkConInfoTableLabel,
          mkApEntryLabel,
          mkApInfoTableLabel,
          mkClosureTableLabel,
          mkBytesLabel,
  
          mkLocalBlockLabel,
  
          mkBlockInfoTableLabel,
  
          mkBitmapLabel,
          mkStringLitLabel,
  
          mkInitializerStubLabel,
          mkInitializerArrayLabel,
          mkFinalizerStubLabel,
          mkFinalizerArrayLabel,
  
          mkAsmTempLabel,
          mkAsmTempDerivedLabel,
          mkAsmTempEndLabel,
          mkAsmTempProcEndLabel,
          mkAsmTempDieLabel,
  
          mkDirty_MUT_VAR_Label,
          mkMUT_VAR_CLEAN_infoLabel,
          mkNonmovingWriteBarrierEnabledLabel,
          mkOrigThunkInfoLabel,
          mkUpdInfoLabel,
          mkBHUpdInfoLabel,
          mkIndStaticInfoLabel,
          mkMainCapabilityLabel,
          mkMAP_FROZEN_CLEAN_infoLabel,
          mkMAP_FROZEN_DIRTY_infoLabel,
          mkMAP_DIRTY_infoLabel,
          mkSMAP_FROZEN_CLEAN_infoLabel,
          mkSMAP_FROZEN_DIRTY_infoLabel,
          mkSMAP_DIRTY_infoLabel,
          mkBadAlignmentLabel,
          mkOutOfBoundsAccessLabel,
          mkMemcpyRangeOverlapLabel,
          mkArrWords_infoLabel,
          mkSRTInfoLabel,
  
          mkTopTickyCtrLabel,
          mkCAFBlackHoleInfoTableLabel,
          mkRtsPrimOpLabel,
          mkRtsSlowFastTickyCtrLabel,
          mkRtsUnpackCStringLabel,
          mkRtsUnpackCStringUtf8Label,
  
          mkSelectorInfoLabel,
          mkSelectorEntryLabel,
          mkCmmInfoLabel,
          mkCmmEntryLabel,
          mkCmmRetInfoLabel,
          mkCmmRetLabel,
          mkCmmCodeLabel,
          mkCmmDataLabel,
          mkRtsCmmDataLabel,
          mkCmmClosureLabel,
          mkRtsApFastLabel,
          mkPrimCallLabel,
          mkForeignLabel,
          mkCCLabel,
          mkCCSLabel,
          mkIPELabel,
          InfoProvEnt(..),
  
          mkDynamicLinkerLabel,
          mkPicBaseLabel,
          mkDeadStripPreventer,
          mkHpcTicksLabel,
  
          -- * Predicates
          hasCAF,
          needsCDecl,
          maybeLocalBlockLabel,
          externallyVisibleCLabel,
          isMathFun,
          isCFunctionLabel,
          isGcPtrLabel,
          labelDynamic,
          isLocalCLabel,
          mayRedirectTo,
          isInfoTableLabel,
          isCmmInfoTableLabel,
          isConInfoTableLabel,
          isIdLabel,
          isTickyLabel,
          hasHaskellName,
          hasIdLabelInfo,
          isBytesLabel,
          isForeignLabel,
          isSomeRODataLabel,
          isStaticClosureLabel,
  
          -- * Conversions
          toClosureLbl,
          toSlowEntryLbl,
          toEntryLbl,
          toInfoLbl,
          toProcDelimiterLbl,
  
          -- * Pretty-printing
          LabelStyle (..),
          pprDebugCLabel,
          pprCLabel,
          pprAsmLabel,
          ppInternalProcLabel,
  
          -- * Others
          dynamicLinkerLabelInfo,
          CStubLabel (..),
          cStubLabel,
          fromCStubLabel,
          mapInternalNonDetUniques
      ) where
  
  import GHC.Prelude
  
  import GHC.Types.Id.Info
  import GHC.Types.Basic
  import {-# SOURCE #-} GHC.Cmm.BlockId (BlockId, mkBlockId)
  import GHC.Unit.Types
  import GHC.Types.Name
  import GHC.Types.Unique
  import GHC.Builtin.PrimOps
  import GHC.Types.CostCentre
  import GHC.Utils.Outputable
  import GHC.Utils.Panic
  import GHC.Data.FastString
  import GHC.Platform
  import GHC.Types.Unique.Set
  import GHC.Core.Ppr ( {- instances -} )
  import GHC.Types.SrcLoc
  
  import qualified Data.Semigroup as S
  
  -- -----------------------------------------------------------------------------
  -- The CLabel type
  
  {- |
    'CLabel' is an abstract type that supports the following operations:
  
    - Pretty printing
  
    - In a C file, does it need to be declared before use?  (i.e. is it
      guaranteed to be already in scope in the places we need to refer to it?)
  
    - If it needs to be declared, what type (code or data) should it be
      declared to have?
  
    - Is it visible outside this object file or not?
  
    - Is it "dynamic" (see details below)
  
    - Eq and Ord, so that we can make sets of CLabels (currently only
      used in outputting C as far as I can tell, to avoid generating
      more than one declaration for any given label).
  
    - Converting an info table label into an entry label.
  
    CLabel usage is a bit messy in GHC as they are used in a number of different
    contexts:
  
    - By the C-- AST to identify labels
  
    - By the unregisterised C code generator (\"PprC\") for naming functions (hence
      the name 'CLabel')
  
    - By the native and LLVM code generators to identify labels
  
    For extra fun, each of these uses a slightly different subset of constructors
    (e.g. 'AsmTempLabel' and 'AsmTempDerivedLabel' are used only in the NCG and
    LLVM backends).
  
    In general, we use 'IdLabel' to represent Haskell things early in the
    pipeline. However, later optimization passes will often represent blocks they
    create with 'LocalBlockLabel' where there is no obvious 'Name' to hang off the
    label.
  -}
  
  data CLabel
    = -- | A label related to the definition of a particular Id or Con in a .hs file.
      IdLabel
          Name
          CafInfo
          IdLabelInfo             -- ^ encodes the suffix of the label
  
    -- | A label from a .cmm file that is not associated with a .hs level Id.
    | CmmLabel
          UnitId                  -- ^ what package the label belongs to.
          NeedExternDecl          -- ^ does the label need an "extern .." declaration
          FastString              -- ^ identifier giving the prefix of the label
          CmmLabelInfo            -- ^ encodes the suffix of the label
  
    -- | A label with a baked-in \/ algorithmically generated name that definitely
    --    comes from the RTS. The code for it must compile into libHSrts.a \/ libHSrts.so
    --    If it doesn't have an algorithmically generated name then use a CmmLabel
    --    instead and give it an appropriate UnitId argument.
    | RtsLabel
          RtsLabelInfo
  
    -- | A label associated with a block. These aren't visible outside of the
    -- compilation unit in which they are defined. These are generally used to
    -- name blocks produced by Cmm-to-Cmm passes and the native code generator,
    -- where we don't have a 'Name' to associate the label to and therefore can't
    -- use 'IdLabel'.
    | LocalBlockLabel
          {-# UNPACK #-} !Unique
  
    -- | A 'C' (or otherwise foreign) label.
    --
    | ForeignLabel
          FastString              -- ^ name of the imported label.
  
          ForeignLabelSource      -- ^ what package the foreign label is in.
  
          FunctionOrData
  
    -- | Local temporary label used for native (or LLVM) code generation; must not
    -- appear outside of these contexts. Use primarily for debug information
    | AsmTempLabel
          {-# UNPACK #-} !Unique
  
    -- | A label \"derived\" from another 'CLabel' by the addition of a suffix.
    -- Must not occur outside of the NCG or LLVM code generators.
    | AsmTempDerivedLabel
          CLabel
          FastString              -- ^ suffix
  
    | StringLitLabel
          {-# UNPACK #-} !Unique
  
    | CC_Label  CostCentre
    | CCS_Label CostCentreStack
    | IPE_Label InfoProvEnt
  
      -- | A per-module metadata label.
    | ModuleLabel !Module ModuleLabelKind
  
    -- | These labels are generated and used inside the NCG only.
    --    They are special variants of a label used for dynamic linking
    --    see module "GHC.CmmToAsm.PIC" for details.
    | DynamicLinkerLabel DynamicLinkerLabelInfo CLabel
  
    -- | This label is generated and used inside the NCG only.
    --    It is used as a base for PIC calculations on some platforms.
    --    It takes the form of a local numeric assembler label '1'; and
    --    is pretty-printed as 1b, referring to the previous definition
    --    of 1: in the assembler source file.
    | PicBaseLabel
  
    -- | A label before an info table to prevent excessive dead-stripping on darwin
    | DeadStripPreventer CLabel
  
    -- | Per-module table of tick locations
    | HpcTicksLabel Module
  
    -- | Static reference table
    | SRTLabel
          {-# UNPACK #-} !Unique
  
    -- | A bitmap (function or case return)
    | LargeBitmapLabel
          {-# UNPACK #-} !Unique
  
    deriving Eq
  
  instance Show CLabel where
    show = showPprUnsafe . pprDebugCLabel genericPlatform
  
  data ModuleLabelKind
      = MLK_Initializer LexicalFastString
      | MLK_InitializerArray
      | MLK_Finalizer LexicalFastString
      | MLK_FinalizerArray
      | MLK_IPEBuffer
      deriving (Eq, Ord)
  
  pprModuleLabelKind :: IsLine doc => ModuleLabelKind -> doc
  pprModuleLabelKind MLK_InitializerArray                    = text "init_arr"
  pprModuleLabelKind (MLK_Initializer (LexicalFastString s)) = text "init__" <> ftext s
  pprModuleLabelKind MLK_FinalizerArray                      = text "fini_arr"
  pprModuleLabelKind (MLK_Finalizer (LexicalFastString s))   = text "fini__" <> ftext s
  pprModuleLabelKind MLK_IPEBuffer                           = text "ipe_buf"
  {-# SPECIALIZE pprModuleLabelKind :: ModuleLabelKind -> SDoc #-}
  {-# SPECIALIZE pprModuleLabelKind :: ModuleLabelKind -> HLine #-} -- see Note [SPECIALIZE to HDoc] in GHC.Utils.Outputable
  
  isIdLabel :: CLabel -> Bool
  isIdLabel IdLabel{} = True
  isIdLabel _ = False
  
  -- Used in SRT analysis. See Note [Ticky labels in SRT analysis] in
  -- GHC.Cmm.Info.Build.
  isTickyLabel :: CLabel -> Bool
  isTickyLabel (IdLabel _ _ IdTickyInfo{}) = True
  isTickyLabel _ = False
  
  -- | Indicate if "GHC.CmmToC" has to generate an extern declaration for the
  -- label (e.g. "extern StgWordArray(foo)").  The type is fixed to StgWordArray.
  --
  -- Symbols from the RTS don't need "extern" declarations because they are
  -- exposed via "rts/include/Stg.h" with the appropriate type. See 'needsCDecl'.
  --
  -- The fixed StgWordArray type led to "conflicting types" issues with user
  -- provided Cmm files (not in the RTS) that declare data of another type (#15467
  -- and test for #17920).  Hence the Cmm parser considers that labels in data
  -- sections don't need the "extern" declaration (just add one explicitly if you
  -- need it).
  --
  -- See https://gitlab.haskell.org/ghc/ghc/-/wikis/commentary/compiler/backends/ppr-c#prototypes
  -- for why extern declaration are needed at all.
  newtype NeedExternDecl
     = NeedExternDecl Bool
     deriving (Ord,Eq)
  
  -- This is laborious, but necessary. We can't derive Ord because
  -- Unique has a special Ord instance that cares for object determinism.
  -- Note nonDetCmpUnique and stableNameCmp in the implementation:
  --  * If -fobject-determinism, the internal uniques will be renamed, thus the
  --  comparison will actually be deterministic
  --  * Stable name compare guarantees deterministic ordering of Names despite
  --  the non-deterministic uniques underlying external names (which aren't
  --  renamed on -fobject-determinism).
  -- See Note [Unique Determinism and code generation] and Note [Object determinism]
  instance Ord CLabel where
    compare (IdLabel a1 b1 c1)
            (IdLabel a2 b2 c2)
            | isExternalName a1, isExternalName a2 = stableNameCmp a1 a2 S.<> compare b1 b2 S.<> compare c1 c2
            | isExternalName a1 = GT
            | isExternalName a2 = LT
  
    compare (IdLabel a1 b1 c1) (IdLabel a2 b2 c2) =
      -- Comparing names here should deterministic because all unique should have
      -- been renamed deterministically, and external names compared above.
      compare a1 a2 S.<>
      compare b1 b2 S.<>
      compare c1 c2
    compare (CmmLabel a1 b1 c1 d1) (CmmLabel a2 b2 c2 d2) =
      compare a1 a2 S.<>
      compare b1 b2 S.<>
      -- This is not non-deterministic because the uniques have been deterministically renamed.
      -- See Note [Object determinism]
      uniqCompareFS c1 c2 S.<>
      compare d1 d2
    compare (RtsLabel a1) (RtsLabel a2) = compare a1 a2
    compare (LocalBlockLabel u1) (LocalBlockLabel u2) = nonDetCmpUnique u1 u2
    compare (ForeignLabel a1 b1 c1) (ForeignLabel a2 b2 c2) =
      uniqCompareFS a1 a2 S.<>
      compare b1 b2 S.<>
      compare c1 c2
    compare (AsmTempLabel u1) (AsmTempLabel u2) = nonDetCmpUnique u1 u2
    compare (AsmTempDerivedLabel a1 b1) (AsmTempDerivedLabel a2 b2) =
      compare a1 a2 S.<>
      lexicalCompareFS b1 b2
    compare (StringLitLabel u1) (StringLitLabel u2) =
      nonDetCmpUnique u1 u2
    compare (CC_Label a1) (CC_Label a2) =
      compare a1 a2
    compare (CCS_Label a1) (CCS_Label a2) =
      compare a1 a2
    compare (IPE_Label a1) (IPE_Label a2) =
      compare a1 a2
    compare (ModuleLabel m1 k1) (ModuleLabel m2 k2) =
      compare m1 m2 S.<>
      compare k1 k2
    compare (DynamicLinkerLabel a1 b1) (DynamicLinkerLabel a2 b2) =
      compare a1 a2 S.<>
      compare b1 b2
    compare PicBaseLabel PicBaseLabel = EQ
    compare (DeadStripPreventer a1) (DeadStripPreventer a2) =
      compare a1 a2
    compare (HpcTicksLabel a1) (HpcTicksLabel a2) =
      compare a1 a2
    compare (SRTLabel u1) (SRTLabel u2) =
      nonDetCmpUnique u1 u2
    compare (LargeBitmapLabel u1) (LargeBitmapLabel u2) =
      nonDetCmpUnique u1 u2
    compare IdLabel{} _ = LT
    compare _ IdLabel{} = GT
    compare CmmLabel{} _ = LT
    compare _ CmmLabel{} = GT
    compare RtsLabel{} _ = LT
    compare _ RtsLabel{} = GT
    compare LocalBlockLabel{} _ = LT
    compare _ LocalBlockLabel{} = GT
    compare ForeignLabel{} _ = LT
    compare _ ForeignLabel{} = GT
    compare AsmTempLabel{} _ = LT
    compare _ AsmTempLabel{} = GT
    compare AsmTempDerivedLabel{} _ = LT
    compare _ AsmTempDerivedLabel{} = GT
    compare StringLitLabel{} _ = LT
    compare _ StringLitLabel{} = GT
    compare CC_Label{} _ = LT
    compare _ CC_Label{} = GT
    compare CCS_Label{} _ = LT
    compare _ CCS_Label{} = GT
    compare DynamicLinkerLabel{} _ = LT
    compare _ DynamicLinkerLabel{} = GT
    compare PicBaseLabel{} _ = LT
    compare _ PicBaseLabel{} = GT
    compare DeadStripPreventer{} _ = LT
    compare _ DeadStripPreventer{} = GT
    compare HpcTicksLabel{} _ = LT
    compare _ HpcTicksLabel{} = GT
    compare SRTLabel{} _ = LT
    compare _ SRTLabel{} = GT
    compare (IPE_Label {}) _ = LT
    compare  _ (IPE_Label{}) = GT
    compare (ModuleLabel {}) _ = LT
    compare  _ (ModuleLabel{}) = GT
  
  -- | Record where a foreign label is stored.
  data ForeignLabelSource
  
     -- | Label is in a named package
     = ForeignLabelInPackage UnitId
  
     -- | Label is in some external, system package that doesn't also
     --   contain compiled Haskell code, and is not associated with any .hi files.
     --   We don't have to worry about Haskell code being inlined from
     --   external packages. It is safe to treat the RTS package as "external".
     | ForeignLabelInExternalPackage
  
     -- | Label is in the package currently being compiled.
     --   This is only used for creating hacky tmp labels during code generation.
     --   Don't use it in any code that might be inlined across a package boundary
     --   (ie, core code) else the information will be wrong relative to the
     --   destination module.
     | ForeignLabelInThisPackage
  
     deriving (Eq, Ord)
  
  
  -- | For debugging problems with the CLabel representation.
  --      We can't make a Show instance for CLabel because lots of its components don't have instances.
  --      The regular Outputable instance only shows the label name, and not its other info.
  --
  pprDebugCLabel :: Platform -> CLabel -> SDoc
  pprDebugCLabel platform lbl = pprAsmLabel platform lbl <> parens extra
     where
        extra = case lbl of
           IdLabel _ _ info
              -> text "IdLabel" <> whenPprDebug (text ":" <> ppr info)
  
           CmmLabel pkg _ext _name _info
              -> text "CmmLabel" <+> ppr pkg
  
           RtsLabel{}
              -> text "RtsLabel"
  
           ForeignLabel _name src funOrData
               -> text "ForeignLabel" <+> ppr src <+> ppr funOrData
  
           _  -> text "other CLabel"
  
  -- Dynamic ticky info for the id.
  data TickyIdInfo
    = TickyRednCounts           -- ^ Used for dynamic allocations
    | TickyInferedTag !Unique    -- ^ Used to track dynamic hits of tag inference.
    deriving (Eq,Show)
  
  instance Outputable TickyIdInfo where
      ppr TickyRednCounts = text "ct_rdn"
      ppr (TickyInferedTag unique) = text "ct_tag[" <> ppr unique <> char ']'
  
  -- | Don't depend on this if you need determinism.
  -- No determinism in the ncg backend, so we use the unique for Ord.
  -- Even if it pains me slightly.
  instance Ord TickyIdInfo where
      compare TickyRednCounts TickyRednCounts = EQ
      compare TickyRednCounts _ = LT
      compare _ TickyRednCounts = GT
      compare (TickyInferedTag unique1) (TickyInferedTag unique2) =
        nonDetCmpUnique unique1 unique2
  
  
  data IdLabelInfo
    = Closure             -- ^ Label for closure
    | InfoTable           -- ^ Info tables for closures; always read-only
    | Entry               -- ^ Entry point
    | Slow                -- ^ Slow entry point
  
    | LocalInfoTable      -- ^ Like InfoTable but not externally visible
    | LocalEntry          -- ^ Like Entry but not externally visible
  
    | IdTickyInfo !TickyIdInfo -- ^ Label of place to keep Ticky-ticky hit info for this Id
  
    | ConEntry ConInfoTableLocation
    -- ^ Constructor entry point, when `-fdistinct-info-tables` is enabled then
    -- each usage of a constructor will be given a unique number and a fresh info
    -- table will be created in the module where the constructor is used. The
    -- argument is used to keep track of which info table a usage of a constructor
    -- should use. When the argument is 'Nothing' then it uses the info table which
    -- is defined in the module where the datatype is declared, this is the usual case.
    -- When it is (Just (m, k)) it will use the kth info table defined in module m. The
    -- point of this inefficiency is so that you can work out where allocations of data
    -- constructors are coming from when you are debugging.
  
    | ConInfoTable ConInfoTableLocation        -- ^ Corresponding info table
  
    | ClosureTable        -- ^ Table of closures for Enum tycons
  
    | Bytes               -- ^ Content of a string literal. See
                          -- Note [Bytes label].
    | BlockInfoTable      -- ^ Like LocalInfoTable but for a proc-point block
                          -- instead of a closure entry-point.
                          -- See Note [Proc-point local block entry-points].
  
    deriving (Eq, Ord)
  
  -- | Which module is the info table from, and which number was it.
  data ConInfoTableLocation = UsageSite Module Int
                            | DefinitionSite
                                deriving (Eq, Ord)
  
  instance Outputable ConInfoTableLocation where
    ppr (UsageSite m n) = text "Loc(" <> ppr n <> text "):" <+> ppr m
    ppr DefinitionSite = empty
  
  getConInfoTableLocation :: IdLabelInfo -> Maybe ConInfoTableLocation
  getConInfoTableLocation (ConInfoTable ci) = Just ci
  getConInfoTableLocation _ = Nothing
  
  instance Outputable IdLabelInfo where
    ppr Closure    = text "Closure"
    ppr InfoTable  = text "InfoTable"
    ppr Entry      = text "Entry"
    ppr Slow       = text "Slow"
  
    ppr LocalInfoTable  = text "LocalInfoTable"
    ppr LocalEntry      = text "LocalEntry"
  
    ppr (ConEntry mn) = text "ConEntry" <+> ppr mn
    ppr (ConInfoTable mn) = text "ConInfoTable" <+> ppr mn
    ppr ClosureTable = text "ClosureTable"
    ppr Bytes        = text "Bytes"
    ppr BlockInfoTable  = text "BlockInfoTable"
    ppr (IdTickyInfo info) = text "IdTickyInfo" <+> ppr info
  
  
  data RtsLabelInfo
    = RtsSelectorInfoTable Bool{-updatable-} Int{-offset-}  -- ^ Selector thunks
    | RtsSelectorEntry     Bool{-updatable-} Int{-offset-}
  
    | RtsApInfoTable       Bool{-updatable-} Int{-arity-}    -- ^ AP thunks
    | RtsApEntry           Bool{-updatable-} Int{-arity-}
  
    | RtsUnpackCStringInfoTable
    | RtsUnpackCStringUtf8InfoTable
    | RtsPrimOp            PrimOp
    | RtsApFast            NonDetFastString    -- ^ _fast versions of generic apply
    | RtsSlowFastTickyCtr String
  
    deriving (Eq,Ord)
  
  
  -- | What type of Cmm label we're dealing with.
  --      Determines the suffix appended to the name when a CLabel.CmmLabel
  --      is pretty printed.
  data CmmLabelInfo
    = CmmInfo                     -- ^ misc rts info tables,      suffix _info
    | CmmEntry                    -- ^ misc rts entry points,     suffix _entry
    | CmmRetInfo                  -- ^ misc rts ret info tables,  suffix _info
    | CmmRet                      -- ^ misc rts return points,    suffix _ret
    | CmmData                     -- ^ misc rts data bits, eg CHARLIKE_closure
    | CmmCode                     -- ^ misc rts code
    | CmmClosure                  -- ^ closures eg CHARLIKE_closure
    | CmmPrimCall                 -- ^ a prim call to some hand written Cmm code
    deriving (Eq, Ord)
  
  data DynamicLinkerLabelInfo
    = CodeStub                    -- MachO: Lfoo$stub, ELF: foo@plt
    | SymbolPtr                   -- MachO: Lfoo$non_lazy_ptr, Windows: __imp_foo
    | GotSymbolPtr                -- ELF: foo@got
    | GotSymbolOffset             -- ELF: foo@gotoff
  
    deriving (Eq, Ord)
  
  
  -- -----------------------------------------------------------------------------
  -- Constructing CLabels
  -- -----------------------------------------------------------------------------
  
  -- Constructing IdLabels
  -- These are always local:
  
  mkSRTLabel     :: Unique -> CLabel
  mkSRTLabel u = SRTLabel u
  
  -- See Note [ticky for LNE]
  mkRednCountsLabel :: Name -> CLabel
  mkRednCountsLabel name = IdLabel name NoCafRefs (IdTickyInfo TickyRednCounts)
  
  mkTagHitLabel :: Name -> Unique -> CLabel
  mkTagHitLabel name !uniq = IdLabel name NoCafRefs (IdTickyInfo (TickyInferedTag uniq))
  
  mkClosureLabel              :: Name -> CafInfo -> CLabel
  mkInfoTableLabel            :: Name -> CafInfo -> CLabel
  mkEntryLabel                :: Name -> CafInfo -> CLabel
  mkClosureTableLabel         :: Name -> CafInfo -> CLabel
  mkConInfoTableLabel         :: Name -> ConInfoTableLocation -> CLabel
  mkBytesLabel                :: Name -> CLabel
  mkClosureLabel name         c     = IdLabel name c Closure
  -- | Decides between external and local labels based on the names externality.
  mkInfoTableLabel name       c
    | isExternalName name = IdLabel name c InfoTable
    | otherwise           = IdLabel name c LocalInfoTable
  mkEntryLabel name           c     = IdLabel name c Entry
  mkClosureTableLabel name    c     = IdLabel name c ClosureTable
  -- Special case for the normal 'DefinitionSite' case so that the 'ConInfoTable' application can be floated to a CAF.
  mkConInfoTableLabel name DefinitionSite = IdLabel name NoCafRefs (ConInfoTable DefinitionSite)
  mkConInfoTableLabel name k = IdLabel name NoCafRefs (ConInfoTable k)
  mkBytesLabel name                 = IdLabel name NoCafRefs Bytes
  
  mkBlockInfoTableLabel :: Name -> CafInfo -> CLabel
  mkBlockInfoTableLabel name c = IdLabel name c BlockInfoTable
                                 -- See Note [Proc-point local block entry-points].
  
  -- Constructing Cmm Labels
  mkDirty_MUT_VAR_Label,
      mkNonmovingWriteBarrierEnabledLabel,
      mkOrigThunkInfoLabel, mkUpdInfoLabel,
      mkBHUpdInfoLabel, mkIndStaticInfoLabel, mkMainCapabilityLabel,
      mkMAP_FROZEN_CLEAN_infoLabel, mkMAP_FROZEN_DIRTY_infoLabel,
      mkMAP_DIRTY_infoLabel,
      mkArrWords_infoLabel,
      mkTopTickyCtrLabel,
      mkCAFBlackHoleInfoTableLabel,
      mkSMAP_FROZEN_CLEAN_infoLabel, mkSMAP_FROZEN_DIRTY_infoLabel,
      mkSMAP_DIRTY_infoLabel, mkBadAlignmentLabel,
      mkOutOfBoundsAccessLabel, mkMemcpyRangeOverlapLabel,
      mkMUT_VAR_CLEAN_infoLabel :: CLabel
  mkDirty_MUT_VAR_Label           = mkForeignLabel (fsLit "dirty_MUT_VAR") ForeignLabelInExternalPackage IsFunction
  mkNonmovingWriteBarrierEnabledLabel
                                  = CmmLabel rtsUnitId (NeedExternDecl False) (fsLit "nonmoving_write_barrier_enabled") CmmData
  mkOrigThunkInfoLabel            = CmmLabel rtsUnitId (NeedExternDecl False) (fsLit "stg_orig_thunk_info_frame") CmmInfo
  mkUpdInfoLabel                  = CmmLabel rtsUnitId (NeedExternDecl False) (fsLit "stg_upd_frame")         CmmInfo
  mkBHUpdInfoLabel                = CmmLabel rtsUnitId (NeedExternDecl False) (fsLit "stg_bh_upd_frame" )     CmmInfo
  mkIndStaticInfoLabel            = CmmLabel rtsUnitId (NeedExternDecl False) (fsLit "stg_IND_STATIC")        CmmInfo
  mkMainCapabilityLabel           = CmmLabel rtsUnitId (NeedExternDecl False) (fsLit "MainCapability")        CmmData
  mkMAP_FROZEN_CLEAN_infoLabel    = CmmLabel rtsUnitId (NeedExternDecl False) (fsLit "stg_MUT_ARR_PTRS_FROZEN_CLEAN") CmmInfo
  mkMAP_FROZEN_DIRTY_infoLabel    = CmmLabel rtsUnitId (NeedExternDecl False) (fsLit "stg_MUT_ARR_PTRS_FROZEN_DIRTY") CmmInfo
  mkMAP_DIRTY_infoLabel           = CmmLabel rtsUnitId (NeedExternDecl False) (fsLit "stg_MUT_ARR_PTRS_DIRTY") CmmInfo
  mkTopTickyCtrLabel              = CmmLabel rtsUnitId (NeedExternDecl False) (fsLit "top_ct")                CmmData
  mkCAFBlackHoleInfoTableLabel    = CmmLabel rtsUnitId (NeedExternDecl False) (fsLit "stg_CAF_BLACKHOLE")     CmmInfo
  mkArrWords_infoLabel            = CmmLabel rtsUnitId (NeedExternDecl False) (fsLit "stg_ARR_WORDS")         CmmInfo
  mkSMAP_FROZEN_CLEAN_infoLabel   = CmmLabel rtsUnitId (NeedExternDecl False) (fsLit "stg_SMALL_MUT_ARR_PTRS_FROZEN_CLEAN") CmmInfo
  mkSMAP_FROZEN_DIRTY_infoLabel   = CmmLabel rtsUnitId (NeedExternDecl False) (fsLit "stg_SMALL_MUT_ARR_PTRS_FROZEN_DIRTY") CmmInfo
  mkSMAP_DIRTY_infoLabel          = CmmLabel rtsUnitId (NeedExternDecl False) (fsLit "stg_SMALL_MUT_ARR_PTRS_DIRTY") CmmInfo
  mkBadAlignmentLabel             = CmmLabel rtsUnitId (NeedExternDecl False) (fsLit "stg_badAlignment")      CmmEntry
  mkOutOfBoundsAccessLabel        = mkForeignLabel (fsLit "rtsOutOfBoundsAccess") ForeignLabelInExternalPackage IsFunction
  mkMemcpyRangeOverlapLabel       = mkForeignLabel (fsLit "rtsMemcpyRangeOverlap") ForeignLabelInExternalPackage IsFunction
  mkMUT_VAR_CLEAN_infoLabel       = CmmLabel rtsUnitId (NeedExternDecl False) (fsLit "stg_MUT_VAR_CLEAN")     CmmInfo
  
  mkSRTInfoLabel :: Int -> CLabel
  mkSRTInfoLabel n = CmmLabel rtsUnitId (NeedExternDecl False) lbl CmmInfo
   where
     lbl =
       case n of
         1 -> fsLit "stg_SRT_1"
         2 -> fsLit "stg_SRT_2"
         3 -> fsLit "stg_SRT_3"
         4 -> fsLit "stg_SRT_4"
         5 -> fsLit "stg_SRT_5"
         6 -> fsLit "stg_SRT_6"
         7 -> fsLit "stg_SRT_7"
         8 -> fsLit "stg_SRT_8"
         9 -> fsLit "stg_SRT_9"
         10 -> fsLit "stg_SRT_10"
         11 -> fsLit "stg_SRT_11"
         12 -> fsLit "stg_SRT_12"
         13 -> fsLit "stg_SRT_13"
         14 -> fsLit "stg_SRT_14"
         15 -> fsLit "stg_SRT_15"
         16 -> fsLit "stg_SRT_16"
         _ -> panic "mkSRTInfoLabel"
  
  -----
  mkCmmInfoLabel,   mkCmmEntryLabel, mkCmmRetInfoLabel, mkCmmRetLabel,
    mkCmmCodeLabel, mkCmmClosureLabel
          :: UnitId -> FastString -> CLabel
  
  mkCmmDataLabel    :: UnitId -> NeedExternDecl -> FastString -> CLabel
  mkRtsCmmDataLabel :: FastString -> CLabel
  
  mkCmmInfoLabel       pkg str     = CmmLabel pkg (NeedExternDecl True) str CmmInfo
  mkCmmEntryLabel      pkg str     = CmmLabel pkg (NeedExternDecl True) str CmmEntry
  mkCmmRetInfoLabel    pkg str     = CmmLabel pkg (NeedExternDecl True) str CmmRetInfo
  mkCmmRetLabel        pkg str     = CmmLabel pkg (NeedExternDecl True) str CmmRet
  mkCmmCodeLabel       pkg str     = CmmLabel pkg (NeedExternDecl True) str CmmCode
  mkCmmClosureLabel    pkg str     = CmmLabel pkg (NeedExternDecl True) str CmmClosure
  mkCmmDataLabel       pkg ext str = CmmLabel pkg ext  str CmmData
  mkRtsCmmDataLabel    str         = CmmLabel rtsUnitId (NeedExternDecl False)  str CmmData
                                      -- RTS symbols don't need "GHC.CmmToC" to
                                      -- generate \"extern\" declaration (they are
                                      -- exposed via rts/include/Stg.h)
  
  mkLocalBlockLabel :: Unique -> CLabel
  mkLocalBlockLabel u = LocalBlockLabel u
  
  -- Constructing RtsLabels
  mkRtsPrimOpLabel :: PrimOp -> CLabel
  mkRtsPrimOpLabel primop = RtsLabel (RtsPrimOp primop)
  
  mkSelectorInfoLabel :: Platform -> Bool -> Int -> CLabel
  mkSelectorInfoLabel platform upd offset =
     assert (offset >= 0 && offset <= pc_MAX_SPEC_SELECTEE_SIZE (platformConstants platform)) $
     RtsLabel (RtsSelectorInfoTable upd offset)
  
  mkSelectorEntryLabel :: Platform -> Bool -> Int -> CLabel
  mkSelectorEntryLabel platform upd offset =
     assert (offset >= 0 && offset <= pc_MAX_SPEC_SELECTEE_SIZE (platformConstants platform)) $
     RtsLabel (RtsSelectorEntry upd offset)
  
  mkApInfoTableLabel :: Platform -> Bool -> Int -> CLabel
  mkApInfoTableLabel platform upd arity =
     assert (arity > 0 && arity <= pc_MAX_SPEC_AP_SIZE (platformConstants platform)) $
     RtsLabel (RtsApInfoTable upd arity)
  
  mkApEntryLabel :: Platform -> Bool -> Int -> CLabel
  mkApEntryLabel platform upd arity =
     assert (arity > 0 && arity <= pc_MAX_SPEC_AP_SIZE (platformConstants platform)) $
     RtsLabel (RtsApEntry upd arity)
  
  -- A call to some primitive hand written Cmm code
  mkPrimCallLabel :: PrimCall -> CLabel
  mkPrimCallLabel (PrimCall str pkg)
          = CmmLabel (toUnitId pkg) (NeedExternDecl True) str CmmPrimCall
  
  
  -- Constructing ForeignLabels
  
  -- | Make a foreign label
  mkForeignLabel
          :: FastString           -- name
          -> ForeignLabelSource   -- what package it's in
          -> FunctionOrData
          -> CLabel
  
  mkForeignLabel = ForeignLabel
  
  -- | Whether label is a top-level string literal
  isBytesLabel :: CLabel -> Bool
  isBytesLabel (IdLabel _ _ Bytes) = True
  isBytesLabel _lbl = False
  
  -- | Whether label is a non-haskell label (defined in C code)
  isForeignLabel :: CLabel -> Bool
  isForeignLabel (ForeignLabel _ _ _) = True
  isForeignLabel _lbl = False
  
  -- | Whether label is a static closure label (can come from haskell or cmm)
  isStaticClosureLabel :: CLabel -> Bool
  -- Closure defined in haskell (.hs)
  isStaticClosureLabel (IdLabel _ _ Closure) = True
  -- Closure defined in cmm
  isStaticClosureLabel (CmmLabel _ _ _ CmmClosure) = True
  isStaticClosureLabel _lbl = False
  
  -- | Whether label is a .rodata label
  isSomeRODataLabel :: CLabel -> Bool
  -- info table defined in haskell (.hs)
  isSomeRODataLabel (IdLabel _ _ ClosureTable) = True
  isSomeRODataLabel (IdLabel _ _ ConInfoTable {}) = True
  isSomeRODataLabel (IdLabel _ _ InfoTable) = True
  isSomeRODataLabel (IdLabel _ _ LocalInfoTable) = True
  isSomeRODataLabel (IdLabel _ _ BlockInfoTable) = True
  -- info table defined in cmm (.cmm)
  isSomeRODataLabel (CmmLabel _ _ _ CmmInfo) = True
  isSomeRODataLabel (CmmLabel _ _ _ CmmRetInfo) = True
  isSomeRODataLabel _lbl = False
  
  -- | Whether label is points to some kind of info table
  isInfoTableLabel :: CLabel -> Bool
  isInfoTableLabel (IdLabel _ _ InfoTable)      = True
  isInfoTableLabel (IdLabel _ _ LocalInfoTable) = True
  isInfoTableLabel (IdLabel _ _ ConInfoTable {})   = True
  isInfoTableLabel (IdLabel _ _ BlockInfoTable) = True
  isInfoTableLabel (CmmLabel _ _ _ CmmInfo)     = True
  isInfoTableLabel _                            = False
  
  -- | Whether label points to an info table defined in Cmm
  isCmmInfoTableLabel :: CLabel -> Bool
  isCmmInfoTableLabel (CmmLabel _ _ _ CmmInfo) = True
  isCmmInfoTableLabel _ = False
  
  -- | Whether label is points to constructor info table
  isConInfoTableLabel :: CLabel -> Bool
  isConInfoTableLabel (IdLabel _ _ ConInfoTable {})   = True
  isConInfoTableLabel _                            = False
  
  -- Constructing Large*Labels
  mkBitmapLabel   :: Unique -> CLabel
  mkBitmapLabel   uniq            = LargeBitmapLabel uniq
  
  -- | Info Table Provenance Entry
  -- See Note [Mapping Info Tables to Source Positions]
  data InfoProvEnt = InfoProvEnt
                                 { infoTablePtr :: !CLabel
                                 -- Address of the info table
                                 , infoProvEntClosureType :: !Int
                                 -- The closure type of the info table (from ClosureMacros.h)
                                 , infoTableType :: !String
                                 -- The rendered Haskell type of the closure the table represents
                                 , infoProvModule :: !Module
                                 -- Origin module
                                 , infoTableProv :: !(Maybe (RealSrcSpan, LexicalFastString)) }
                                 -- Position and information about the info table
                                 deriving (Eq, Ord)
  
  instance OutputableP Platform InfoProvEnt where
    pdoc platform (InfoProvEnt clabel _ _ _ _) = pdoc platform clabel
  
  -- Constructing Cost Center Labels
  mkCCLabel  :: CostCentre      -> CLabel
  mkCCSLabel :: CostCentreStack -> CLabel
  mkIPELabel :: Module          -> CLabel
  mkCCLabel           cc          = CC_Label cc
  mkCCSLabel          ccs         = CCS_Label ccs
  mkIPELabel          mod         = ModuleLabel mod MLK_IPEBuffer
  
  mkRtsApFastLabel :: FastString -> CLabel
  mkRtsApFastLabel str = RtsLabel (RtsApFast (NonDetFastString str))
  
  mkRtsSlowFastTickyCtrLabel :: String -> CLabel
  mkRtsSlowFastTickyCtrLabel pat = RtsLabel (RtsSlowFastTickyCtr pat)
  
  -- | A standard string unpacking thunk. See Note [unpack_cstring closures] in
  -- StgStdThunks.cmm.
  mkRtsUnpackCStringLabel, mkRtsUnpackCStringUtf8Label :: CLabel
  mkRtsUnpackCStringLabel = RtsLabel RtsUnpackCStringInfoTable
  mkRtsUnpackCStringUtf8Label = RtsLabel RtsUnpackCStringUtf8InfoTable
  
  -- Constructing Code Coverage Labels
  mkHpcTicksLabel :: Module -> CLabel
  mkHpcTicksLabel                = HpcTicksLabel
  
  
  -- Constructing labels used for dynamic linking
  mkDynamicLinkerLabel :: DynamicLinkerLabelInfo -> CLabel -> CLabel
  mkDynamicLinkerLabel            = DynamicLinkerLabel
  
  dynamicLinkerLabelInfo :: CLabel -> Maybe (DynamicLinkerLabelInfo, CLabel)
  dynamicLinkerLabelInfo (DynamicLinkerLabel info lbl) = Just (info, lbl)
  dynamicLinkerLabelInfo _        = Nothing
  
  mkPicBaseLabel :: CLabel
  mkPicBaseLabel                  = PicBaseLabel
  
  
  -- Constructing miscellaneous other labels
  mkDeadStripPreventer :: CLabel -> CLabel
  mkDeadStripPreventer lbl        = DeadStripPreventer lbl
  
  mkStringLitLabel :: Unique -> CLabel
  mkStringLitLabel                = StringLitLabel
  
  mkInitializerStubLabel :: Module -> FastString -> CLabel
  mkInitializerStubLabel mod s    = ModuleLabel mod (MLK_Initializer (LexicalFastString s))
  
  mkInitializerArrayLabel :: Module -> CLabel
  mkInitializerArrayLabel mod     = ModuleLabel mod MLK_InitializerArray
  
  
  mkFinalizerStubLabel :: Module -> FastString -> CLabel
  mkFinalizerStubLabel mod s      = ModuleLabel mod (MLK_Finalizer (LexicalFastString s))
  
  mkFinalizerArrayLabel :: Module -> CLabel
  mkFinalizerArrayLabel mod       = ModuleLabel mod MLK_FinalizerArray
  
  mkAsmTempLabel :: Uniquable a => a -> CLabel
  mkAsmTempLabel a                = AsmTempLabel (getUnique a)
  
  mkAsmTempDerivedLabel :: CLabel -> FastString -> CLabel
  mkAsmTempDerivedLabel = AsmTempDerivedLabel
  
  mkAsmTempEndLabel :: CLabel -> CLabel
  mkAsmTempEndLabel l = mkAsmTempDerivedLabel l (fsLit "_end")
  
  -- | A label indicating the end of a procedure.
  mkAsmTempProcEndLabel :: CLabel -> CLabel
  mkAsmTempProcEndLabel l = mkAsmTempDerivedLabel l (fsLit "_proc_end")
  
  -- | Construct a label for a DWARF Debug Information Entity (DIE)
  -- describing another symbol.
  mkAsmTempDieLabel :: CLabel -> CLabel
  mkAsmTempDieLabel l = mkAsmTempDerivedLabel l (fsLit "_die")
  
  -- -----------------------------------------------------------------------------
  -- Convert between different kinds of label
  
  toClosureLbl :: Platform -> CLabel -> CLabel
  toClosureLbl platform lbl = case lbl of
     IdLabel n c _        -> IdLabel n c Closure
     CmmLabel m ext str _ -> CmmLabel m ext str CmmClosure
     _                    -> pprPanic "toClosureLbl" (pprDebugCLabel platform lbl)
  
  toSlowEntryLbl :: Platform -> CLabel -> CLabel
  toSlowEntryLbl platform lbl = case lbl of
     IdLabel n _ BlockInfoTable -> pprPanic "toSlowEntryLbl" (ppr n)
     IdLabel n c _              -> IdLabel n c Slow
     _                          -> pprPanic "toSlowEntryLbl" (pprDebugCLabel platform lbl)
  
  toEntryLbl :: Platform -> CLabel -> CLabel
  toEntryLbl platform lbl = case lbl of
     IdLabel n c LocalInfoTable    -> IdLabel n c LocalEntry
     IdLabel n c (ConInfoTable k)  -> IdLabel n c (ConEntry k)
  
     IdLabel n _ BlockInfoTable    -> mkLocalBlockLabel (nameUnique n)
                     -- See Note [Proc-point local block entry-points].
     IdLabel n c _                 -> IdLabel n c Entry
     CmmLabel m ext str CmmInfo    -> CmmLabel m ext str CmmEntry
     CmmLabel m ext str CmmRetInfo -> CmmLabel m ext str CmmRet
     _                             -> pprPanic "toEntryLbl" (pprDebugCLabel platform lbl)
  
  -- | Generate a CmmProc delimiter label from the actual entry label.
  --
  -- This delimiter label might be the entry label itself, except when the entry
  -- label is a LocalBlockLabel. If we reused the entry label to delimit the proc,
  -- we would generate redundant labels (see #22792)
  toProcDelimiterLbl :: CLabel -> CLabel
  toProcDelimiterLbl lbl = case lbl of
    LocalBlockLabel {} -> mkAsmTempDerivedLabel lbl (fsLit "_entry")
    _                  -> lbl
  
  toInfoLbl :: Platform -> CLabel -> CLabel
  toInfoLbl platform lbl = case lbl of
     IdLabel n c LocalEntry      -> IdLabel n c LocalInfoTable
     IdLabel n c (ConEntry k)    -> IdLabel n c (ConInfoTable k)
  
     IdLabel n c _               -> IdLabel n c InfoTable
     CmmLabel m ext str CmmEntry -> CmmLabel m ext str CmmInfo
     CmmLabel m ext str CmmRet   -> CmmLabel m ext str CmmRetInfo
     _                           -> pprPanic "CLabel.toInfoLbl" (pprDebugCLabel platform lbl)
  
  hasHaskellName :: CLabel -> Maybe Name
  hasHaskellName (IdLabel n _ _) = Just n
  hasHaskellName _               = Nothing
  
  hasIdLabelInfo :: CLabel -> Maybe IdLabelInfo
  hasIdLabelInfo (IdLabel _ _ l) = Just l
  hasIdLabelInfo _ = Nothing
  
  -- -----------------------------------------------------------------------------
  -- Does a CLabel's referent itself refer to a CAF?
  hasCAF :: CLabel -> Bool
  hasCAF (IdLabel _ _ (IdTickyInfo TickyRednCounts)) = False -- See Note [ticky for LNE]
  hasCAF (IdLabel _ MayHaveCafRefs _) = True
  hasCAF (RtsLabel RtsUnpackCStringInfoTable) = True
  hasCAF (RtsLabel RtsUnpackCStringUtf8InfoTable) = True
    -- The info table stg_MK_STRING_info is for thunks
  hasCAF _                            = False
  
  -- Note [ticky for LNE]
  -- ~~~~~~~~~~~~~~~~~~~~~
  -- Until 14 Feb 2013, every ticky counter was associated with a
  -- closure. Thus, ticky labels used IdLabel. It is odd that
  -- GHC.Cmm.Info.Build.cafTransfers would consider such a ticky label
  -- reason to add the name to the CAFEnv (and thus eventually the SRT),
  -- but it was harmless because the ticky was only used if the closure
  -- was also.
  --
  -- Since we now have ticky counters for LNEs, it is no longer the case
  -- that every ticky counter has an actual closure. So I changed the
  -- generation of ticky counters' CLabels to not result in their
  -- associated id ending up in the SRT.
  --
  -- NB IdLabel is still appropriate for ticky ids (as opposed to
  -- CmmLabel) because the LNE's counter is still related to an .hs Id,
  -- that Id just isn't for a proper closure.
  
  -- -----------------------------------------------------------------------------
  -- Does a CLabel need declaring before use or not?
  --
  -- See wiki:commentary/compiler/backends/ppr-c#prototypes
  
  needsCDecl :: CLabel -> Bool
    -- False <=> it's pre-declared; don't bother
    -- don't bother declaring Bitmap labels, we always make sure
    -- they are defined before use.
  needsCDecl (SRTLabel _)                 = True
  needsCDecl (LargeBitmapLabel _)         = False
  needsCDecl (IdLabel _ _ _)              = True
  needsCDecl (LocalBlockLabel _)          = True
  
  needsCDecl (StringLitLabel _)           = False
  needsCDecl (AsmTempLabel _)             = False
  needsCDecl (AsmTempDerivedLabel _ _)    = False
  needsCDecl (RtsLabel _)                 = False
  
  needsCDecl (CmmLabel pkgId (NeedExternDecl external) _ _)
          -- local labels mustn't have it
          | not external                  = False
  
          -- Prototypes for labels defined in the runtime system are imported
          --      into HC files via rts/include/Stg.h.
          | pkgId == rtsUnitId            = False
  
          -- For other labels we inline one into the HC file directly.
          | otherwise                     = True
  
  needsCDecl l@(ForeignLabel{})           = not (isMathFun l)
  needsCDecl (CC_Label _)                 = True
  needsCDecl (CCS_Label _)                = True
  needsCDecl (IPE_Label {})               = True
  needsCDecl (ModuleLabel _ kind)         = modLabelNeedsCDecl kind
  needsCDecl (HpcTicksLabel _)            = True
  needsCDecl (DynamicLinkerLabel {})      = panic "needsCDecl DynamicLinkerLabel"
  needsCDecl PicBaseLabel                 = panic "needsCDecl PicBaseLabel"
  needsCDecl (DeadStripPreventer {})      = panic "needsCDecl DeadStripPreventer"
  
  modLabelNeedsCDecl :: ModuleLabelKind -> Bool
  -- Code for finalizers and initializers are emitted in stub objects
  modLabelNeedsCDecl (MLK_Initializer _)  = True
  modLabelNeedsCDecl (MLK_Finalizer   _)  = True
  modLabelNeedsCDecl MLK_IPEBuffer        = True
  -- The finalizer and initializer arrays are emitted in the code of the module
  modLabelNeedsCDecl MLK_InitializerArray = False
  modLabelNeedsCDecl MLK_FinalizerArray   = False
  
  -- | If a label is a local block label then return just its 'BlockId', otherwise
  -- 'Nothing'.
  maybeLocalBlockLabel :: CLabel -> Maybe BlockId
  maybeLocalBlockLabel (LocalBlockLabel uq)  = Just $ mkBlockId uq
  maybeLocalBlockLabel _                     = Nothing
  
  
  -- | Check whether a label corresponds to a C function that has
  --      a prototype in a system header somewhere, or is built-in
  --      to the C compiler. For these labels we avoid generating our
  --      own C prototypes.
  isMathFun :: CLabel -> Bool
  isMathFun (ForeignLabel fs _ _)       = fs `elementOfUniqSet` math_funs
  isMathFun _ = False
  
  math_funs :: UniqSet FastString
  math_funs = mkUniqSet [
          -- _ISOC99_SOURCE
          (fsLit "acos"),         (fsLit "acosf"),        (fsLit "acosh"),
          (fsLit "acoshf"),       (fsLit "acoshl"),       (fsLit "acosl"),
          (fsLit "asin"),         (fsLit "asinf"),        (fsLit "asinl"),
          (fsLit "asinh"),        (fsLit "asinhf"),       (fsLit "asinhl"),
          (fsLit "atan"),         (fsLit "atanf"),        (fsLit "atanl"),
          (fsLit "atan2"),        (fsLit "atan2f"),       (fsLit "atan2l"),
          (fsLit "atanh"),        (fsLit "atanhf"),       (fsLit "atanhl"),
          (fsLit "cbrt"),         (fsLit "cbrtf"),        (fsLit "cbrtl"),
          (fsLit "ceil"),         (fsLit "ceilf"),        (fsLit "ceill"),
          (fsLit "copysign"),     (fsLit "copysignf"),    (fsLit "copysignl"),
          (fsLit "cos"),          (fsLit "cosf"),         (fsLit "cosl"),
          (fsLit "cosh"),         (fsLit "coshf"),        (fsLit "coshl"),
          (fsLit "erf"),          (fsLit "erff"),         (fsLit "erfl"),
          (fsLit "erfc"),         (fsLit "erfcf"),        (fsLit "erfcl"),
          (fsLit "exp"),          (fsLit "expf"),         (fsLit "expl"),
          (fsLit "exp2"),         (fsLit "exp2f"),        (fsLit "exp2l"),
          (fsLit "expm1"),        (fsLit "expm1f"),       (fsLit "expm1l"),
          (fsLit "fabs"),         (fsLit "fabsf"),        (fsLit "fabsl"),
          (fsLit "fdim"),         (fsLit "fdimf"),        (fsLit "fdiml"),
          (fsLit "floor"),        (fsLit "floorf"),       (fsLit "floorl"),
          (fsLit "fma"),          (fsLit "fmaf"),         (fsLit "fmal"),
          (fsLit "fmax"),         (fsLit "fmaxf"),        (fsLit "fmaxl"),
          (fsLit "fmin"),         (fsLit "fminf"),        (fsLit "fminl"),
          (fsLit "fmod"),         (fsLit "fmodf"),        (fsLit "fmodl"),
          (fsLit "frexp"),        (fsLit "frexpf"),       (fsLit "frexpl"),
          (fsLit "hypot"),        (fsLit "hypotf"),       (fsLit "hypotl"),
          (fsLit "ilogb"),        (fsLit "ilogbf"),       (fsLit "ilogbl"),
          (fsLit "ldexp"),        (fsLit "ldexpf"),       (fsLit "ldexpl"),
          (fsLit "lgamma"),       (fsLit "lgammaf"),      (fsLit "lgammal"),
          (fsLit "llrint"),       (fsLit "llrintf"),      (fsLit "llrintl"),
          (fsLit "llround"),      (fsLit "llroundf"),     (fsLit "llroundl"),
          (fsLit "log"),          (fsLit "logf"),         (fsLit "logl"),
          (fsLit "log10l"),       (fsLit "log10"),        (fsLit "log10f"),
          (fsLit "log1pl"),       (fsLit "log1p"),        (fsLit "log1pf"),
          (fsLit "log2"),         (fsLit "log2f"),        (fsLit "log2l"),
          (fsLit "logb"),         (fsLit "logbf"),        (fsLit "logbl"),
          (fsLit "lrint"),        (fsLit "lrintf"),       (fsLit "lrintl"),
          (fsLit "lround"),       (fsLit "lroundf"),      (fsLit "lroundl"),
          (fsLit "modf"),         (fsLit "modff"),        (fsLit "modfl"),
          (fsLit "nan"),          (fsLit "nanf"),         (fsLit "nanl"),
          (fsLit "nearbyint"),    (fsLit "nearbyintf"),   (fsLit "nearbyintl"),
          (fsLit "nextafter"),    (fsLit "nextafterf"),   (fsLit "nextafterl"),
          (fsLit "nexttoward"),   (fsLit "nexttowardf"),  (fsLit "nexttowardl"),
          (fsLit "pow"),          (fsLit "powf"),         (fsLit "powl"),
          (fsLit "remainder"),    (fsLit "remainderf"),   (fsLit "remainderl"),
          (fsLit "remquo"),       (fsLit "remquof"),      (fsLit "remquol"),
          (fsLit "rint"),         (fsLit "rintf"),        (fsLit "rintl"),
          (fsLit "round"),        (fsLit "roundf"),       (fsLit "roundl"),
          (fsLit "scalbln"),      (fsLit "scalblnf"),     (fsLit "scalblnl"),
          (fsLit "scalbn"),       (fsLit "scalbnf"),      (fsLit "scalbnl"),
          (fsLit "sin"),          (fsLit "sinf"),         (fsLit "sinl"),
          (fsLit "sinh"),         (fsLit "sinhf"),        (fsLit "sinhl"),
          (fsLit "sqrt"),         (fsLit "sqrtf"),        (fsLit "sqrtl"),
          (fsLit "tan"),          (fsLit "tanf"),         (fsLit "tanl"),
          (fsLit "tanh"),         (fsLit "tanhf"),        (fsLit "tanhl"),
          (fsLit "tgamma"),       (fsLit "tgammaf"),      (fsLit "tgammal"),
          (fsLit "trunc"),        (fsLit "truncf"),       (fsLit "truncl"),
          -- ISO C 99 also defines these function-like macros in math.h:
          -- fpclassify, isfinite, isinf, isnormal, signbit, isgreater,
          -- isgreaterequal, isless, islessequal, islessgreater, isunordered
  
          -- additional symbols from _BSD_SOURCE
          (fsLit "drem"),         (fsLit "dremf"),        (fsLit "dreml"),
          (fsLit "finite"),       (fsLit "finitef"),      (fsLit "finitel"),
          (fsLit "gamma"),        (fsLit "gammaf"),       (fsLit "gammal"),
          (fsLit "isinf"),        (fsLit "isinff"),       (fsLit "isinfl"),
          (fsLit "isnan"),        (fsLit "isnanf"),       (fsLit "isnanl"),
          (fsLit "j0"),           (fsLit "j0f"),          (fsLit "j0l"),
          (fsLit "j1"),           (fsLit "j1f"),          (fsLit "j1l"),
          (fsLit "jn"),           (fsLit "jnf"),          (fsLit "jnl"),
          (fsLit "lgamma_r"),     (fsLit "lgammaf_r"),    (fsLit "lgammal_r"),
          (fsLit "scalb"),        (fsLit "scalbf"),       (fsLit "scalbl"),
          (fsLit "significand"),  (fsLit "significandf"), (fsLit "significandl"),
          (fsLit "y0"),           (fsLit "y0f"),          (fsLit "y0l"),
          (fsLit "y1"),           (fsLit "y1f"),          (fsLit "y1l"),
          (fsLit "yn"),           (fsLit "ynf"),          (fsLit "ynl"),
  
          -- These functions are described in IEEE Std 754-2008 -
          -- Standard for Floating-Point Arithmetic and ISO/IEC TS 18661
          (fsLit "nextup"),       (fsLit "nextupf"),      (fsLit "nextupl"),
          (fsLit "nextdown"),     (fsLit "nextdownf"),    (fsLit "nextdownl")
      ]
  
  -- -----------------------------------------------------------------------------
  -- | Is a CLabel visible outside this object file or not?
  --      From the point of view of the code generator, a name is
  --      externally visible if it has to be declared as exported
  --      in the .o file's symbol table; that is, made non-static.
  externallyVisibleCLabel :: CLabel -> Bool -- not C "static"
  externallyVisibleCLabel (StringLitLabel _)      = False
  externallyVisibleCLabel (AsmTempLabel _)        = False
  externallyVisibleCLabel (AsmTempDerivedLabel _ _)= False
  externallyVisibleCLabel (RtsLabel _)            = True
  externallyVisibleCLabel (LocalBlockLabel _)     = False
  externallyVisibleCLabel (CmmLabel _ _ _ _)      = True
  externallyVisibleCLabel (ForeignLabel{})        = True
  externallyVisibleCLabel (IdLabel name _ info)   = isExternalName name && externallyVisibleIdLabel info
  externallyVisibleCLabel (CC_Label _)            = True
  externallyVisibleCLabel (CCS_Label _)           = True
  externallyVisibleCLabel (IPE_Label {})          = True
  externallyVisibleCLabel (ModuleLabel {})        = True
  externallyVisibleCLabel (DynamicLinkerLabel _ _)  = False
  externallyVisibleCLabel (HpcTicksLabel _)       = True
  externallyVisibleCLabel (LargeBitmapLabel _)    = False
  externallyVisibleCLabel (SRTLabel _)            = False
  externallyVisibleCLabel (PicBaseLabel {}) = panic "externallyVisibleCLabel PicBaseLabel"
  externallyVisibleCLabel (DeadStripPreventer {}) = panic "externallyVisibleCLabel DeadStripPreventer"
  
  externallyVisibleIdLabel :: IdLabelInfo -> Bool
  externallyVisibleIdLabel LocalInfoTable  = False
  externallyVisibleIdLabel LocalEntry      = False
  externallyVisibleIdLabel BlockInfoTable  = False
  externallyVisibleIdLabel _               = True
  
  -- -----------------------------------------------------------------------------
  -- Finding the "type" of a CLabel
  
  -- For generating correct types in label declarations:
  
  data CLabelType
    = CodeLabel   -- Address of some executable instructions
    | DataLabel   -- Address of data, not a GC ptr
    | GcPtrLabel  -- Address of a (presumably static) GC object
  
  isCFunctionLabel :: CLabel -> Bool
  isCFunctionLabel lbl = case labelType lbl of
                          CodeLabel -> True
                          _other    -> False
  
  isGcPtrLabel :: CLabel -> Bool
  isGcPtrLabel lbl = case labelType lbl of
                          GcPtrLabel -> True
                          _other     -> False
  
  
  -- | Work out the general type of data at the address of this label
  --    whether it be code, data, or static GC object.
  labelType :: CLabel -> CLabelType
  labelType (IdLabel _ _ info)                    = idInfoLabelType info
  labelType (CmmLabel _ _ _ CmmData)              = DataLabel
  labelType (CmmLabel _ _ _ CmmClosure)           = GcPtrLabel
  labelType (CmmLabel _ _ _ CmmCode)              = CodeLabel
  labelType (CmmLabel _ _ _ CmmInfo)              = DataLabel
  labelType (CmmLabel _ _ _ CmmEntry)             = CodeLabel
  labelType (CmmLabel _ _ _ CmmPrimCall)          = CodeLabel
  labelType (CmmLabel _ _ _ CmmRetInfo)           = DataLabel
  labelType (CmmLabel _ _ _ CmmRet)               = CodeLabel
  labelType (RtsLabel (RtsSelectorInfoTable _ _)) = DataLabel
  labelType (RtsLabel (RtsSelectorEntry _ _))     = CodeLabel
  labelType (RtsLabel (RtsApInfoTable _ _))       = DataLabel
  labelType (RtsLabel (RtsApEntry _ _))           = CodeLabel
  labelType (RtsLabel (RtsApFast _))              = CodeLabel
  labelType (RtsLabel RtsUnpackCStringInfoTable)  = DataLabel
  labelType (RtsLabel RtsUnpackCStringUtf8InfoTable)
                                                  = DataLabel
  labelType (RtsLabel (RtsPrimOp _))              = CodeLabel
  labelType (RtsLabel (RtsSlowFastTickyCtr _))    = DataLabel
  labelType (LocalBlockLabel _)                   = CodeLabel
  labelType (SRTLabel _)                          = DataLabel
  labelType (ForeignLabel _ _ IsFunction)         = CodeLabel
  labelType (ForeignLabel _ _ IsData)             = DataLabel
  labelType (AsmTempLabel _)                      = panic "labelType(AsmTempLabel)"
  labelType (AsmTempDerivedLabel _ _)             = panic "labelType(AsmTempDerivedLabel)"
  labelType (StringLitLabel _)                    = DataLabel
  labelType (CC_Label _)                          = DataLabel
  labelType (CCS_Label _)                         = DataLabel
  labelType (IPE_Label {})                        = DataLabel
  labelType (ModuleLabel _ kind)                  = moduleLabelKindType kind
  labelType (DynamicLinkerLabel _ _)              = DataLabel -- Is this right?
  labelType PicBaseLabel                          = DataLabel
  labelType (DeadStripPreventer _)                = DataLabel
  labelType (HpcTicksLabel _)                     = DataLabel
  labelType (LargeBitmapLabel _)                  = DataLabel
  
  moduleLabelKindType :: ModuleLabelKind -> CLabelType
  moduleLabelKindType kind =
    case kind of
      MLK_Initializer _    -> CodeLabel
      MLK_InitializerArray -> DataLabel
      MLK_Finalizer _      -> CodeLabel
      MLK_FinalizerArray   -> DataLabel
      MLK_IPEBuffer        -> DataLabel
  
  idInfoLabelType :: IdLabelInfo -> CLabelType
  idInfoLabelType info =
    case info of
      InfoTable     -> DataLabel
      LocalInfoTable -> DataLabel
      BlockInfoTable -> DataLabel
      Closure       -> GcPtrLabel
      ConInfoTable {} -> DataLabel
      ClosureTable  -> DataLabel
      IdTickyInfo{} -> DataLabel
      Bytes         -> DataLabel
      _             -> CodeLabel
  
  
  -- -----------------------------------------------------------------------------
  
  -- | Is a 'CLabel' defined in the current module being compiled?
  --
  -- Sometimes we can optimise references within a compilation unit in ways that
  -- we couldn't for inter-module references. This provides a conservative
  -- estimate of whether a 'CLabel' lives in the current module.
  isLocalCLabel :: Module -> CLabel -> Bool
  isLocalCLabel this_mod lbl =
    case lbl of
      IdLabel name _ _
        | isInternalName name -> True
        | otherwise           -> nameModule name == this_mod
      LocalBlockLabel _       -> True
      _                       -> False
  
  -- -----------------------------------------------------------------------------
  
  -- | Does a 'CLabel' need dynamic linkage?
  --
  -- When referring to data in code, we need to know whether
  -- that data resides in a DLL or not. [Win32 only.]
  -- @labelDynamic@ returns @True@ if the label is located
  -- in a DLL, be it a data reference or not.
  labelDynamic :: Module -> Platform -> Bool -> CLabel -> Bool
  labelDynamic this_mod platform external_dynamic_refs lbl =
    case lbl of
     -- is the RTS in a DLL or not?
     RtsLabel _ ->
       external_dynamic_refs && (this_unit /= rtsUnitId)
  
     IdLabel n _ _ ->
       external_dynamic_refs && isDynLinkName platform this_mod n
  
     -- When compiling in the "dyn" way, each package is to be linked into
     -- its own shared library.
     CmmLabel lbl_unit _ _ _
      | os == OSMinGW32 -> external_dynamic_refs && (this_unit /= lbl_unit)
      | otherwise       -> external_dynamic_refs
  
     LocalBlockLabel _    -> False
  
     ForeignLabel _ source _  ->
         if os == OSMinGW32
         then case source of
              -- Foreign label is in some un-named foreign package (or DLL).
              ForeignLabelInExternalPackage -> True
  
              -- Foreign label is linked into the same package as the
              -- source file currently being compiled.
              ForeignLabelInThisPackage -> False
  
              -- Foreign label is in some named package.
              -- When compiling in the "dyn" way, each package is to be
              -- linked into its own DLL.
              ForeignLabelInPackage pkgId ->
                  external_dynamic_refs && (this_unit /= pkgId)
  
         else -- On Mac OS X and on ELF platforms, false positives are OK,
              -- so we claim that all foreign imports come from dynamic
              -- libraries
              True
  
     CC_Label cc ->
       external_dynamic_refs && not (ccFromThisModule cc this_mod)
  
     -- CCS_Label always contains a CostCentre defined in the current module
     CCS_Label _ -> False
     IPE_Label {} -> True
  
     HpcTicksLabel m ->
       external_dynamic_refs && this_mod /= m
  
     -- Note that DynamicLinkerLabels do NOT require dynamic linking themselves.
     _                 -> False
    where
      os        = platformOS platform
      this_unit = toUnitId (moduleUnit this_mod)
  
  -----------------------------------------------------------------------------
  -- Printing out CLabels.
  
  {-
  Convention:
  
        <name>_<type>
  
  where <name> is <Module>_<name> for external names and <unique> for
  internal names. <type> is one of the following:
  
           info                   Info table
           srt                    Static reference table
           entry                  Entry code (function, closure)
           slow                   Slow entry code (if any)
           ret                    Direct return address
           vtbl                   Vector table
           <n>_alt                Case alternative (tag n)
           dflt                   Default case alternative
           btm                    Large bitmap vector
           closure                Static closure
           con_entry              Dynamic Constructor entry code
           con_info               Dynamic Constructor info table
           static_entry           Static Constructor entry code
           static_info            Static Constructor info table
           sel_info               Selector info table
           sel_entry              Selector entry code
           cc                     Cost centre
           ccs                    Cost centre stack
  
  Many of these distinctions are only for documentation reasons.  For
  example, _ret is only distinguished from _entry to make it easy to
  tell whether a code fragment is a return point or a closure/function
  entry.
  
  Note [Closure and info labels]
  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  For a function 'foo, we have:
     foo_info    : Points to the info table describing foo's closure
                   (and entry code for foo with tables next to code)
     foo_closure : Static (no-free-var) closure only:
                   points to the statically-allocated closure
  
  For a data constructor (such as Just or Nothing), we have:
      Just_con_info: Info table for the data constructor itself
                     the first word of a heap-allocated Just
      Just_info:     Info table for the *worker function*, an
                     ordinary Haskell function of arity 1 that
                     allocates a (Just x) box:
                        Just = \x -> Just x
      Just_entry:    The entry code for the worker function
      Just_closure:  The closure for this worker
  
      Nothing_closure: a statically allocated closure for Nothing
      Nothing_static_info: info table for Nothing_closure
  
  All these must be exported symbol, EXCEPT Just_info.  We don't need to
  export this because in other modules we either have
         * A reference to 'Just'; use Just_closure
         * A saturated call 'Just x'; allocate using Just_con_info
  Not exporting these Just_info labels reduces the number of symbols
  somewhat.
  
  Note [Bytes label]
  ~~~~~~~~~~~~~~~~~~
  For a top-level string literal 'foo', we have just one symbol 'foo_bytes', which
  points to a static data block containing the content of the literal.
  
  Note [Proc-point local block entry-points]
  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  A label for a proc-point local block entry-point has no "_entry" suffix. With
  `infoTblLbl` we derive an info table label from a proc-point block ID. If
  we convert such an info table label into an entry label we must produce
  the label without an "_entry" suffix. So an info table label records
  the fact that it was derived from a block ID in `IdLabelInfo` as
  `BlockInfoTable`.
  
  The info table label and the local block label are both local labels
  and are not externally visible.
  
  Note [Bangs in CLabel]
  ~~~~~~~~~~~~~~~~~~~~~~
  There are some carefully placed strictness annotations in this module,
  which were discovered in !5226 to significantly reduce compile-time
  allocation.  Take care if you want to remove them!
  
  -}
  
  -- | Style of label pretty-printing.
  --
  -- When we produce C sources or headers, we have to take into account
  -- that C compilers transform C labels when they convert them into
  -- symbols. For example, they can add prefixes (e.g., "_" on Darwin).
  -- So we provide two ways to pretty-print CLabels: C style or Asm
  -- style.
  --
  data LabelStyle
     = CStyle   -- ^ C label style (used by C and LLVM backends)
     | AsmStyle -- ^ Asm label style (used by NCG backend)
  
  pprAsmLabel :: IsLine doc => Platform -> CLabel -> doc
  pprAsmLabel platform lbl = pprCLabelStyle platform AsmStyle lbl
  {-# SPECIALIZE pprAsmLabel :: Platform -> CLabel -> SDoc #-}
  {-# SPECIALIZE pprAsmLabel :: Platform -> CLabel -> HLine #-} -- see Note [SPECIALIZE to HDoc] in GHC.Utils.Outputable
  
  pprCLabel :: IsLine doc => Platform -> CLabel -> doc
  pprCLabel platform lbl = pprCLabelStyle platform CStyle lbl
  {-# SPECIALIZE pprCLabel :: Platform -> CLabel -> SDoc #-}
  {-# SPECIALIZE pprCLabel :: Platform -> CLabel -> HLine #-} -- see Note [SPECIALIZE to HDoc] in GHC.Utils.Outputable
  
  instance OutputableP Platform CLabel where
    {-# INLINE pdoc #-} -- see Note [Bangs in CLabel]
    pdoc !platform lbl = getPprStyle $ \pp_sty ->
                          case pp_sty of
                            PprDump{} -> pprCLabel platform lbl
                            _         -> let lbl_doc = (pprCLabel platform lbl)
                                         in pprTraceUserWarning (text "Labels in code should be printed with pprCLabel or pprAsmLabel" <> lbl_doc) lbl_doc
  
  pprCLabelStyle :: forall doc. IsLine doc => Platform -> LabelStyle -> CLabel -> doc
  pprCLabelStyle !platform !sty lbl = -- see Note [Bangs in CLabel]
    let
      !use_leading_underscores = platformLeadingUnderscore platform
  
      -- some platform (e.g. Darwin) require a leading "_" for exported asm
      -- symbols
      maybe_underscore :: doc -> doc
      maybe_underscore doc = case sty of
        AsmStyle | use_leading_underscores -> pp_cSEP <> doc
        _                                  -> doc
  
      tempLabelPrefixOrUnderscore :: doc
      tempLabelPrefixOrUnderscore = case sty of
        AsmStyle -> asmTempLabelPrefix platform
        CStyle   -> char '_'
  
  
    in case lbl of
     LocalBlockLabel u -> case sty of
        AsmStyle -> tempLabelPrefixOrUnderscore <> pprUniqueAlways u
        CStyle   -> tempLabelPrefixOrUnderscore <> text "blk_" <> pprUniqueAlways u
  
     AsmTempLabel u
        -> tempLabelPrefixOrUnderscore <> pprUniqueAlways u
  
     AsmTempDerivedLabel l suf
           -- we print a derived label, so we just print the parent label
           -- recursively. However we don't want to print the temp prefix (e.g.
           -- ".L") twice, so we must explicitely handle these cases.
        -> let skipTempPrefix = \case
                  AsmTempLabel u            -> pprUniqueAlways u
                  AsmTempDerivedLabel l suf -> skipTempPrefix l <> ftext suf
                  LocalBlockLabel u         -> pprUniqueAlways u
                  lbl                       -> pprAsmLabel platform lbl
           in
           asmTempLabelPrefix platform
           <> skipTempPrefix l
           <> ftext suf
  
     DynamicLinkerLabel info lbl
        -> pprDynamicLinkerAsmLabel platform info (pprAsmLabel platform lbl)
  
     PicBaseLabel
        -> text "1b"
  
     DeadStripPreventer lbl
        ->
        {-
           `lbl` can be temp one but we need to ensure that dsp label will stay
           in the final binary so we prepend non-temp prefix ("dsp_") and
           optional `_` (underscore) because this is how you mark non-temp symbols
           on some platforms (Darwin)
        -}
        maybe_underscore $ text "dsp_" <> pprCLabelStyle platform sty lbl <> text "_dsp"
  
     StringLitLabel u
        -> maybe_underscore $ pprUniqueAlways u <> text "_str"
  
     ForeignLabel fs _ _
        -> maybe_underscore $ ftext fs
  
     IdLabel name _cafs flavor -> case sty of
        AsmStyle -> maybe_underscore $ internalNamePrefix <> pprName name <> ppIdFlavor flavor
                     where
                        isRandomGenerated = not (isExternalName name)
                        internalNamePrefix =
                           if isRandomGenerated
                              then asmTempLabelPrefix platform
                              else empty
        CStyle   -> pprName name <> ppIdFlavor flavor
  
     SRTLabel u
        -> maybe_underscore $ tempLabelPrefixOrUnderscore <> pprUniqueAlways u <> pp_cSEP <> text "srt"
  
     RtsLabel (RtsApFast (NonDetFastString str))
        -> maybe_underscore $ ftext str <> text "_fast"
  
     RtsLabel (RtsSelectorInfoTable upd_reqd offset)
        -> maybe_underscore $ hcat [ text "stg_sel_", int offset
                                   , if upd_reqd
                                      then text "_upd_info"
                                      else text "_noupd_info"
                                   ]
  
     RtsLabel (RtsSelectorEntry upd_reqd offset)
        -> maybe_underscore $ hcat [ text "stg_sel_", int offset
                                   , if upd_reqd
                                      then text "_upd_entry"
                                      else text "_noupd_entry"
                                   ]
  
     RtsLabel (RtsApInfoTable upd_reqd arity)
        -> maybe_underscore $ hcat [ text "stg_ap_", int arity
                                   , if upd_reqd
                                      then text "_upd_info"
                                      else text "_noupd_info"
                                   ]
  
     RtsLabel (RtsApEntry upd_reqd arity)
        -> maybe_underscore $ hcat [ text "stg_ap_", int arity
                                   , if upd_reqd
                                      then text "_upd_entry"
                                      else text "_noupd_entry"
                                   ]
  
     RtsLabel (RtsPrimOp primop)
        -> maybe_underscore $ text "stg_" <> pprPrimOp primop
  
     RtsLabel (RtsSlowFastTickyCtr pat)
        -> maybe_underscore $ text "SLOW_CALL_fast_" <> text pat <> text "_ctr"
  
     RtsLabel RtsUnpackCStringInfoTable
        -> maybe_underscore $ text "stg_unpack_cstring_info"
     RtsLabel RtsUnpackCStringUtf8InfoTable
        -> maybe_underscore $ text "stg_unpack_cstring_utf8_info"
  
     LargeBitmapLabel u
        -> maybe_underscore $ tempLabelPrefixOrUnderscore
                              <> char 'b' <> pprUniqueAlways u <> pp_cSEP <> text "btm"
                              -- Some bitmaps for tuple constructors have a numeric tag (e.g. '7')
                              -- until that gets resolved we'll just force them to start
                              -- with a letter so the label will be legal assembly code.
  
     HpcTicksLabel mod
        -> maybe_underscore $ text "_hpc_tickboxes_"  <> pprModule mod <> text "_hpc"
  
     CC_Label cc   -> maybe_underscore $ pprCostCentre cc
     CCS_Label ccs -> maybe_underscore $ pprCostCentreStack ccs
     IPE_Label (InfoProvEnt l _ _ m _) -> maybe_underscore $ (pprCLabel platform l <> text "_" <> pprModule m <> text "_ipe")
     ModuleLabel mod kind        -> maybe_underscore $ pprModule mod <> text "_" <> pprModuleLabelKind kind
  
     CmmLabel _ _ fs CmmCode     -> maybe_underscore $ ftext fs
     CmmLabel _ _ fs CmmData     -> maybe_underscore $ ftext fs
     CmmLabel _ _ fs CmmPrimCall -> maybe_underscore $ ftext fs
     CmmLabel _ _ fs CmmInfo     -> maybe_underscore $ ftext fs <> text "_info"
     CmmLabel _ _ fs CmmEntry    -> maybe_underscore $ ftext fs <> text "_entry"
     CmmLabel _ _ fs CmmRetInfo  -> maybe_underscore $ ftext fs <> text "_info"
     CmmLabel _ _ fs CmmRet      -> maybe_underscore $ ftext fs <> text "_ret"
     CmmLabel _ _ fs CmmClosure  -> maybe_underscore $ ftext fs <> text "_closure"
  {-# SPECIALIZE pprCLabelStyle :: Platform -> LabelStyle -> CLabel -> SDoc #-}
  {-# SPECIALIZE pprCLabelStyle :: Platform -> LabelStyle -> CLabel -> HLine #-} -- see Note [SPECIALIZE to HDoc] in GHC.Utils.Outputable
  
  -- Note [Internal proc labels]
  -- ~~~~~~~~~~~~~~~~~~~~~~~~~~~
  -- Some tools (e.g. the `perf` utility on Linux) rely on the symbol table
  -- for resolution of function names. To help these tools we provide the
  -- (enabled by default) -fexpose-all-symbols flag which causes GHC to produce
  -- symbols even for symbols with are internal to a module (although such
  -- symbols will have only local linkage).
  --
  -- Note that these labels are *not* referred to by code. They are strictly for
  -- diagnostics purposes.
  --
  -- To avoid confusion, it is desirable to add a module-qualifier to the
  -- symbol name. However, the Name type's Internal constructor doesn't carry
  -- knowledge of the current Module. Consequently, we have to pass this around
  -- explicitly.
  
  -- | Generate a label for a procedure internal to a module (if
  -- 'Opt_ExposeAllSymbols' is enabled).
  -- See Note [Internal proc labels].
  ppInternalProcLabel :: IsLine doc
                      => Module     -- ^ the current module
                      -> CLabel
                      -> Maybe doc -- ^ the internal proc label
  ppInternalProcLabel this_mod (IdLabel nm _ flavour)
    | isInternalName nm
    = Just
       $ text "_" <> pprModule this_mod
      <> char '_'
      <> ztext (zEncodeFS (occNameFS (occName nm)))
      <> char '_'
      <> pprUniqueAlways (getUnique nm)
      <> ppIdFlavor flavour
  ppInternalProcLabel _ _ = Nothing
  {-# SPECIALIZE ppInternalProcLabel :: Module -> CLabel -> Maybe SDoc #-}
  {-# SPECIALIZE ppInternalProcLabel :: Module -> CLabel -> Maybe HLine #-} -- see Note [SPECIALIZE to HDoc] in GHC.Utils.Outputable
  
  ppIdFlavor :: IsLine doc => IdLabelInfo -> doc
  ppIdFlavor x = pp_cSEP <> case x of
     Closure          -> text "closure"
     InfoTable        -> text "info"
     LocalInfoTable   -> text "info"
     Entry            -> text "entry"
     LocalEntry       -> text "entry"
     Slow             -> text "slow"
     IdTickyInfo TickyRednCounts
        -> text "ct"
     IdTickyInfo (TickyInferedTag unique)
        -> text "ct_inf_tag" <> char '_' <> pprUniqueAlways unique
     ConEntry loc      ->
        case loc of
          DefinitionSite -> text "con_entry"
          UsageSite m n ->
            pprModule m <> pp_cSEP <> int n <> pp_cSEP <> text "con_entry"
     ConInfoTable k   ->
      case k of
        DefinitionSite -> text "con_info"
        UsageSite m n ->
          pprModule m <> pp_cSEP <> int n <> pp_cSEP <> text "con_info"
     ClosureTable     -> text "closure_tbl"
     Bytes            -> text "bytes"
     BlockInfoTable   -> text "info"
  
  pp_cSEP :: IsLine doc => doc
  pp_cSEP = char '_'
  
  
  instance Outputable ForeignLabelSource where
   ppr fs
    = case fs of
          ForeignLabelInPackage pkgId     -> parens $ text "package: " <> ppr pkgId
          ForeignLabelInThisPackage       -> parens $ text "this package"
          ForeignLabelInExternalPackage   -> parens $ text "external package"
  
  -- -----------------------------------------------------------------------------
  -- Machine-dependent knowledge about labels.
  
  asmTempLabelPrefix :: IsLine doc => Platform -> doc  -- for formatting labels
  asmTempLabelPrefix !platform = case platformOS platform of
      OSDarwin -> text "L"
      OSAIX    -> text "__L" -- follow IBM XL C's convention
      _        -> text ".L"
  
  pprDynamicLinkerAsmLabel :: IsLine doc => Platform -> DynamicLinkerLabelInfo -> doc -> doc
  pprDynamicLinkerAsmLabel !platform dllInfo ppLbl =
      case platformOS platform of
        OSDarwin
          | platformArch platform == ArchX86_64 ->
            case dllInfo of
              CodeStub        -> char 'L' <> ppLbl <> text "$stub"
              SymbolPtr       -> char 'L' <> ppLbl <> text "$non_lazy_ptr"
              GotSymbolPtr    -> ppLbl <> text "@GOTPCREL"
              GotSymbolOffset -> ppLbl
          | platformArch platform == ArchAArch64 -> ppLbl
          | otherwise -> panic "pprDynamicLinkerAsmLabel"
  
        OSAIX ->
            case dllInfo of
              SymbolPtr -> text "LC.." <> ppLbl -- GCC's naming convention
              _         -> panic "pprDynamicLinkerAsmLabel"
  
        _ | osElfTarget (platformOS platform) -> elfLabel
  
        OSMinGW32 ->
            case dllInfo of
              SymbolPtr -> text "__imp_" <> ppLbl
              _         -> panic "pprDynamicLinkerAsmLabel"
  
        _ -> panic "pprDynamicLinkerAsmLabel"
    where
      elfLabel
        | platformArch platform == ArchPPC
        = case dllInfo of
            CodeStub  -> -- See Note [.LCTOC1 in PPC PIC code]
                         ppLbl <> text "+32768@plt"
            SymbolPtr -> text ".LC_" <> ppLbl
            _         -> panic "pprDynamicLinkerAsmLabel"
  
        | platformArch platform == ArchAArch64
        = ppLbl
  
        | platformArch platform == ArchRISCV64
        = ppLbl
  
        | platformArch platform == ArchLoongArch64
        = ppLbl
  
        | platformArch platform == ArchX86_64
        = case dllInfo of
            CodeStub        -> ppLbl <> text "@plt"
            GotSymbolPtr    -> ppLbl <> text "@gotpcrel"
            GotSymbolOffset -> ppLbl
            SymbolPtr       -> text ".LC_" <> ppLbl
  
        | platformArch platform == ArchPPC_64 ELF_V1
          || platformArch platform == ArchPPC_64 ELF_V2
        = case dllInfo of
            GotSymbolPtr    -> text ".LC_"  <> ppLbl <> text "@toc"
            GotSymbolOffset -> ppLbl
            SymbolPtr       -> text ".LC_" <> ppLbl
            _               -> panic "pprDynamicLinkerAsmLabel"
  
        | otherwise
        = case dllInfo of
            CodeStub        -> ppLbl <> text "@plt"
            SymbolPtr       -> text ".LC_" <> ppLbl
            GotSymbolPtr    -> ppLbl <> text "@got"
            GotSymbolOffset -> ppLbl <> text "@gotoff"
  
  -- Figure out whether `symbol` may serve as an alias
  -- to `target` within one compilation unit.
  --
  -- This is true if any of these holds:
  -- * `target` is a module-internal haskell name.
  -- * `target` is an exported name, but comes from the same
  --   module as `symbol`
  --
  -- These are sufficient conditions for establishing e.g. a
  -- GNU assembly alias ('.equiv' directive). Sadly, there is
  -- no such thing as an alias to an imported symbol (conf.
  -- http://blog.omega-prime.co.uk/2011/07/06/the-sad-state-of-symbol-aliases/)
  -- See Note [emit-time elimination of static indirections].
  --
  -- Precondition is that both labels represent the
  -- same semantic value.
  
  mayRedirectTo :: CLabel -> CLabel -> Bool
  mayRedirectTo symbol target
   | Just nam <- haskellName
   , staticClosureLabel
   , isExternalName nam
   , Just mod <- nameModule_maybe nam
   , Just anam <- hasHaskellName symbol
   , Just amod <- nameModule_maybe anam
   = amod == mod
  
   | Just nam <- haskellName
   , staticClosureLabel
   , isInternalName nam
   = True
  
   | otherwise = False
     where staticClosureLabel = isStaticClosureLabel target
           haskellName = hasHaskellName target
  
  
  {-
  Note [emit-time elimination of static indirections]
  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  As described in #15155, certain static values are representationally
  equivalent, e.g. 'cast'ed values (when created by 'newtype' wrappers).
  
               newtype A = A Int
               {-# NOINLINE a #-}
               a = A 42
  
  a1_rYB :: Int
  [GblId, Caf=NoCafRefs, Unf=OtherCon []]
  a1_rYB = GHC.Types.I# 42#
  
  a [InlPrag=NOINLINE] :: A
  [GblId, Unf=OtherCon []]
  a = a1_rYB `cast` (Sym (T15155.N:A[0]) :: Int ~R# A)
  
  Formerly we created static indirections for these (IND_STATIC), which
  consist of a statically allocated forwarding closure that contains
  the (possibly tagged) indirectee. (See CMM/assembly below.)
  This approach is suboptimal for two reasons:
    (a) they occupy extra space,
    (b) they need to be entered in order to obtain the indirectee,
        thus they cannot be tagged.
  
  Fortunately there is a common case where static indirections can be
  eliminated while emitting assembly (native or LLVM), viz. when the
  indirectee is in the same module (object file) as the symbol that
  points to it. In this case an assembly-level identification can
  be created ('.equiv' directive), and as such the same object will
  be assigned two names in the symbol table. Any of the identified
  symbols can be referenced by a tagged pointer.
  
  Currently the 'mayRedirectTo' predicate will
  give a clue whether a label can be equated with another, already
  emitted, label (which can in turn be an alias). The general mechanics
  is that we identify data (IND_STATIC closures) that are amenable
  to aliasing while pretty-printing of assembly output, and emit the
  '.equiv' directive instead of static data in such a case.
  
  Here is a sketch how the output is massaged:
  
                       Consider
  newtype A = A Int
  {-# NOINLINE a #-}
  a = A 42                                -- I# 42# is the indirectee
                                          -- 'a' is exported
  
                   results in STG
  
  a1_rXq :: GHC.Types.Int
  [GblId, Caf=NoCafRefs, Unf=OtherCon []] =
      CCS_DONT_CARE GHC.Types.I#! [42#];
  
  T15155.a [InlPrag=NOINLINE] :: T15155.A
  [GblId, Unf=OtherCon []] =
      CAF_ccs  \ u  []  a1_rXq;
  
                   and CMM
  
  [section ""data" . a1_rXq_closure" {
       a1_rXq_closure:
           const GHC.Types.I#_con_info;
           const 42;
   }]
  
  [section ""data" . T15155.a_closure" {
       T15155.a_closure:
           const stg_IND_STATIC_info;
           const a1_rXq_closure+1;
           const 0;
           const 0;
   }]
  
  The emitted assembly is
  
  ==== INDIRECTEE
  a1_rXq_closure:                         -- module local haskell value
          .quad   GHC.Types.I#_con_info   -- an Int
          .quad   42
  
  ==== BEFORE
  .globl T15155.a_closure                 -- exported newtype wrapped value
  T15155.a_closure:
          .quad   stg_IND_STATIC_info     -- the closure info
          .quad   a1_rXq_closure+1        -- indirectee ('+1' being the tag)
          .quad   0
          .quad   0
  
  ==== AFTER
  .globl T15155.a_closure                 -- exported newtype wrapped value
  .equiv a1_rXq_closure,T15155.a_closure  -- both are shared
  
  The transformation is performed because
       T15155.a_closure `mayRedirectTo` a1_rXq_closure+1
  returns True.
  -}
  
  -- | This type encodes the subset of 'CLabel' that occurs in C stubs of foreign
  -- declarations for the purpose of serializing to interface files.
  --
  -- See Note [Foreign stubs and TH bytecode linking]
  data CStubLabel =
    CStubLabel {
      csl_is_initializer :: Bool,
      csl_module :: Module,
      csl_name :: FastString
    }
  
  instance Outputable CStubLabel where
    ppr CStubLabel {csl_is_initializer, csl_module, csl_name} =
      text ini <+> ppr csl_module <> colon <> text (unpackFS csl_name)
      where
        ini = if csl_is_initializer then "initializer" else "finalizer"
  
  -- | Project the constructor 'ModuleLabel' out of 'CLabel' if it is an
  -- initializer or finalizer.
  cStubLabel :: CLabel -> Maybe CStubLabel
  cStubLabel = \case
    ModuleLabel csl_module label_kind -> do
      (csl_is_initializer, csl_name) <- case label_kind of
        MLK_Initializer (LexicalFastString s) -> Just (True, s)
        MLK_Finalizer (LexicalFastString s) -> Just (False, s)
        _ -> Nothing
      Just (CStubLabel {csl_is_initializer, csl_module, csl_name})
    _ -> Nothing
  
  -- | Inject a 'CStubLabel' into a 'CLabel' as a 'ModuleLabel'.
  fromCStubLabel :: CStubLabel -> CLabel
  fromCStubLabel (CStubLabel {csl_is_initializer, csl_module, csl_name}) =
    ModuleLabel csl_module (label_kind (LexicalFastString csl_name))
    where
      label_kind =
        if csl_is_initializer
        then MLK_Initializer
        else MLK_Finalizer
  
  -- | A utility for renaming uniques in CLabels to produce deterministic object.
  -- Note that not all Uniques are mapped over. Only those that can be safely alpha
  -- renamed, e.g. uniques of local symbols, but not of external ones.
  -- See Note [Renaming uniques deterministically].
  mapInternalNonDetUniques :: Applicative m => (Unique -> m Unique) -> CLabel -> m CLabel
  -- todo: Can we do less work here, e.g., do we really need to rename AsmTempLabel, LocalBlockLabel?
  mapInternalNonDetUniques f x = case x of
    IdLabel name cafInfo idLabelInfo
      | not (isExternalName name) -> IdLabel . setNameUnique name <$> f (nameUnique name) <*> pure cafInfo <*> pure idLabelInfo
      | otherwise -> pure x
    cl@CmmLabel{} -> pure cl
    RtsLabel rtsLblInfo -> pure $ RtsLabel rtsLblInfo
    LocalBlockLabel unique -> LocalBlockLabel <$> f unique
    fl@ForeignLabel{} -> pure fl
    AsmTempLabel unique -> AsmTempLabel <$> f unique
    AsmTempDerivedLabel clbl fs -> AsmTempDerivedLabel <$> mapInternalNonDetUniques f clbl <*> pure fs
    StringLitLabel unique -> StringLitLabel <$> f unique
    CC_Label  cc -> pure $ CC_Label cc
    CCS_Label ccs -> pure $ CCS_Label ccs
    IPE_Label ipe@InfoProvEnt{infoTablePtr} ->
      (\cl' -> IPE_Label ipe{infoTablePtr = cl'}) <$> mapInternalNonDetUniques f infoTablePtr
    ml@ModuleLabel{} -> pure ml
    DynamicLinkerLabel dlli clbl -> DynamicLinkerLabel dlli <$> mapInternalNonDetUniques f clbl
    PicBaseLabel -> pure PicBaseLabel
    DeadStripPreventer clbl -> DeadStripPreventer <$> mapInternalNonDetUniques f clbl
    HpcTicksLabel mod -> pure $ HpcTicksLabel mod
    SRTLabel unique -> SRTLabel <$> f unique
    LargeBitmapLabel unique -> LargeBitmapLabel <$> f unique
  -- This is called *a lot* if renaming Cmm uniques, and won't specialise without this pragma:
  {-# INLINABLE mapInternalNonDetUniques #-}
  
  