{-# LANGUAGE DeriveFunctor #-}

{-# OPTIONS_GHC -Wno-incomplete-uni-patterns #-}
{-# LANGUAGE NamedFieldPuns #-}

{-
(c) The GRASP/AQUA Project, Glasgow University, 1992-1998
-}

{-| Tidying up Core

This module's purpose is to prepare the Core program for two distinct purposes:
* To be serialised into the module's interface file
* To feed to the code generator

The most important tasks are:
* Determine which `Name`s should ultimately be `Internal` and `External`
  (which may differ to whether they were originally `Internal` or `External`).
  See `Note [About the NameSorts]` in GHC.Types.Name.
  For example, in:
          module M where
            f x = x + y
              where y = factorial 4
  could be optimized during the Core pass to:
          module M where
            y = factorial 4
            f x = x + y
  in which case `y` would be changed from `Internal` to `External`.

* Rename local identifiers to avoid name clashes, so that unfoldings etc can
  be serialialised using the OccName, without Uniques.

  For example (`x_5` means `x` with a `Unique` of `5`):
          f x_12 x_23 = x_12
  would be changed to:
          f x_12 x1_23 = x_12
-}
module GHC.Iface.Tidy
  ( TidyOpts (..)
  , UnfoldingExposure (..)
  , tidyProgram
  , mkBootModDetailsTc
  )
where

import GHC.Prelude

import GHC.Tc.Types
import GHC.Tc.Utils.Env

import GHC.Core
import GHC.Core.Unfold
-- import GHC.Core.Unfold.Make
import GHC.Core.FVs
import GHC.Core.Tidy
import GHC.Core.Seq         ( seqBinds )
import GHC.Core.Opt.Arity   ( exprArity, typeArity, exprBotStrictness_maybe )
import GHC.Core.InstEnv
import GHC.Core.Type
import GHC.Core.DataCon
import GHC.Core.TyCon
import GHC.Core.Class
import GHC.Core.Opt.OccurAnal ( occurAnalyseExpr )

import GHC.Iface.Tidy.StaticPtrTable
import GHC.Iface.Env

import GHC.Utils.Outputable
import GHC.Utils.Misc( filterOut )
import GHC.Utils.Panic
import GHC.Utils.Logger as Logger
import qualified GHC.Utils.Error as Err

import GHC.Types.DefaultEnv ( emptyDefaultEnv )
import GHC.Types.ForeignStubs
import GHC.Types.Var.Env
import GHC.Types.Var.Set
import GHC.Types.Var
import GHC.Types.Id
import GHC.Types.Id.Make ( mkDictSelRhs )
import GHC.Types.Id.Info
import GHC.Types.Demand  ( isDeadEndAppSig, isNopSig, nopSig, isDeadEndSig )
import GHC.Types.Basic
import GHC.Types.Name hiding (varName)
import GHC.Types.Name.Set
import GHC.Types.Name.Cache
import GHC.Types.Avail
import GHC.Types.Tickish
import GHC.Types.TypeEnv
import GHC.Tc.Utils.TcType (tcSplitNestedSigmaTys)

import GHC.Unit.Module
import GHC.Unit.Module.ModGuts
import GHC.Unit.Module.ModDetails
import GHC.Unit.Module.Deps

import GHC.Data.Maybe

import Control.Monad
import Data.Function
import Data.List        ( sortBy, mapAccumL )
import qualified Data.Set as S
import GHC.Types.CostCentre

{-
Constructing the TypeEnv, Instances, Rules from which the
ModIface is constructed, and which goes on to subsequent modules in
--make mode.

Most of the interface file is obtained simply by serialising the
TypeEnv.  One important consequence is that if the *interface file*
has pragma info if and only if the final TypeEnv does. This is not so
important for *this* module, but it's essential for ghc --make:
subsequent compilations must not see (e.g.) the arity if the interface
file does not contain arity If they do, they'll exploit the arity;
then the arity might change, but the iface file doesn't change =>
recompilation does not happen => disaster.

For data types, the final TypeEnv will have a TyThing for the TyCon,
plus one for each DataCon; the interface file will contain just one
data type declaration, but it is de-serialised back into a collection
of TyThings.

************************************************************************
*                                                                      *
                Plan A: simpleTidyPgm
*                                                                      *
************************************************************************


Plan A: mkBootModDetails: omit pragmas, make interfaces small
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
* Ignore the bindings

* Drop all WiredIn things from the TypeEnv
        (we never want them in interface files)

* Retain all TyCons and Classes in the TypeEnv, to avoid
        having to find which ones are mentioned in the
        types of exported Ids

* Trim off the constructors of non-exported TyCons, both
        from the TyCon and from the TypeEnv

* Drop non-exported Ids from the TypeEnv

* Tidy the types of the DFunIds of Instances,
  make them into GlobalIds, (they already have External Names)
  and add them to the TypeEnv

* Tidy the types of the (exported) Ids in the TypeEnv,
  make them into GlobalIds (they already have External Names)

* Drop rules altogether

* Tidy the bindings, to ensure that the Arity
  information is correct for each top-level binder; the
  code generator needs it. And to ensure that local names have
  distinct OccNames in case of object-file splitting

* If this an hsig file, drop the instances altogether too (they'll
  get pulled in by the implicit module import.
-}

-- This is Plan A: make a small type env when typechecking only,
-- or when compiling a hs-boot file, or simply when not using -O
--
-- We don't look at the bindings at all -- there aren't any
-- for hs-boot files

mkBootModDetailsTc :: Logger -> TcGblEnv -> IO ModDetails
mkBootModDetailsTc :: Logger -> TcGblEnv -> IO ModDetails
mkBootModDetailsTc Logger
logger
        TcGblEnv{ tcg_exports :: TcGblEnv -> [AvailInfo]
tcg_exports          = [AvailInfo]
exports,
                  tcg_type_env :: TcGblEnv -> TypeEnv
tcg_type_env         = TypeEnv
type_env, -- just for the Ids
                  tcg_tcs :: TcGblEnv -> [TyCon]
tcg_tcs              = [TyCon]
tcs,
                  tcg_patsyns :: TcGblEnv -> [PatSyn]
tcg_patsyns          = [PatSyn]
pat_syns,
                  tcg_insts :: TcGblEnv -> [ClsInst]
tcg_insts            = [ClsInst]
insts,
                  tcg_fam_insts :: TcGblEnv -> [FamInst]
tcg_fam_insts        = [FamInst]
fam_insts,
                  tcg_complete_matches :: TcGblEnv -> CompleteMatches
tcg_complete_matches = CompleteMatches
complete_matches,
                  tcg_mod :: TcGblEnv -> Module
tcg_mod              = Module
this_mod
                }
  = -- This timing isn't terribly useful since the result isn't forced, but
    -- the message is useful to locating oneself in the compilation process.
    Logger
-> SDoc -> (ModDetails -> ()) -> IO ModDetails -> IO ModDetails
forall (m :: * -> *) a.
MonadIO m =>
Logger -> SDoc -> (a -> ()) -> m a -> m a
Err.withTiming Logger
logger
                   (String -> SDoc
forall doc. IsLine doc => String -> doc
text String
"CoreTidy"SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<+>SDoc -> SDoc
forall doc. IsLine doc => doc -> doc
brackets (Module -> SDoc
forall a. Outputable a => a -> SDoc
ppr Module
this_mod))
                   (() -> ModDetails -> ()
forall a b. a -> b -> a
const ()) (IO ModDetails -> IO ModDetails) -> IO ModDetails -> IO ModDetails
forall a b. (a -> b) -> a -> b
$
    ModDetails -> IO ModDetails
forall a. a -> IO a
forall (m :: * -> *) a. Monad m => a -> m a
return (ModDetails { md_types :: TypeEnv
md_types            = TypeEnv
type_env'
                       , md_defaults :: DefaultEnv
md_defaults         = DefaultEnv
emptyDefaultEnv
                       , md_insts :: InstEnv
md_insts            = InstEnv
insts'
                       , md_fam_insts :: [FamInst]
md_fam_insts        = [FamInst]
fam_insts
                       , md_rules :: [CoreRule]
md_rules            = []
                       , md_anns :: [Annotation]
md_anns             = []
                       , md_exports :: [AvailInfo]
md_exports          = [AvailInfo]
exports
                       , md_complete_matches :: CompleteMatches
md_complete_matches = CompleteMatches
complete_matches
                       })
  where
    -- Find the LocalIds in the type env that are exported
    -- Make them into GlobalIds, and tidy their types
    --
    -- It's very important to remove the non-exported ones
    -- because we don't tidy the OccNames, and if we don't remove
    -- the non-exported ones we'll get many things with the
    -- same name in the interface file, giving chaos.
    --
    -- Do make sure that we keep Ids that are already Global.
    -- When typechecking an .hs-boot file, the Ids come through as
    -- GlobalIds.
    final_ids :: [Id]
final_ids = [ Id -> Id
globaliseAndTidyBootId Id
id
                | Id
id <- TypeEnv -> [Id]
typeEnvIds TypeEnv
type_env
                , Id -> Bool
keep_it Id
id ]

    final_tcs :: [TyCon]
final_tcs  = (TyCon -> Bool) -> [TyCon] -> [TyCon]
forall a. (a -> Bool) -> [a] -> [a]
filterOut TyCon -> Bool
forall thing. NamedThing thing => thing -> Bool
isWiredIn [TyCon]
tcs
                 -- See Note [Drop wired-in things]
    type_env' :: TypeEnv
type_env'  = [Id] -> [TyCon] -> [PatSyn] -> [FamInst] -> TypeEnv
typeEnvFromEntities [Id]
final_ids [TyCon]
final_tcs [PatSyn]
pat_syns [FamInst]
fam_insts
    insts' :: InstEnv
insts'     = TypeEnv -> InstEnv -> InstEnv
mkFinalClsInsts TypeEnv
type_env' (InstEnv -> InstEnv) -> InstEnv -> InstEnv
forall a b. (a -> b) -> a -> b
$ [ClsInst] -> InstEnv
mkInstEnv [ClsInst]
insts

    -- Default methods have their export flag set (isExportedId),
    -- but everything else doesn't (yet), because this is
    -- pre-desugaring, so we must test against the exports too.
    keep_it :: Id -> Bool
keep_it Id
id | Name -> Bool
isWiredInName Name
id_name           = Bool
False
                 -- See Note [Drop wired-in things]
               | Id -> Bool
isExportedId Id
id                 = Bool
True
               | Name
id_name Name -> NameSet -> Bool
`elemNameSet` NameSet
exp_names = Bool
True
               | Bool
otherwise                       = Bool
False
               where
                 id_name :: Name
id_name = Id -> Name
idName Id
id

    exp_names :: NameSet
exp_names = [AvailInfo] -> NameSet
availsToNameSet [AvailInfo]
exports

lookupFinalId :: TypeEnv -> Id -> Id
lookupFinalId :: TypeEnv -> Id -> Id
lookupFinalId TypeEnv
type_env Id
id
  = case TypeEnv -> Name -> Maybe TyThing
lookupTypeEnv TypeEnv
type_env (Id -> Name
idName Id
id) of
      Just (AnId Id
id') -> Id
id'
      Maybe TyThing
_ -> String -> SDoc -> Id
forall a. HasCallStack => String -> SDoc -> a
pprPanic String
"lookup_final_id" (Id -> SDoc
forall a. Outputable a => a -> SDoc
ppr Id
id)

mkFinalClsInsts :: TypeEnv -> InstEnv -> InstEnv
mkFinalClsInsts :: TypeEnv -> InstEnv -> InstEnv
mkFinalClsInsts TypeEnv
env = (Id -> Id) -> InstEnv -> InstEnv
updateClsInstDFuns (TypeEnv -> Id -> Id
lookupFinalId TypeEnv
env)

globaliseAndTidyBootId :: Id -> Id
-- For a LocalId with an External Name,
-- makes it into a GlobalId
--     * unchanged Name (might be Internal or External)
--     * unchanged details
--     * VanillaIdInfo (makes a conservative assumption about arity)
--     * BootUnfolding (see Note [Inlining and hs-boot files] in GHC.CoreToIface)
globaliseAndTidyBootId :: Id -> Id
globaliseAndTidyBootId Id
id
  = (Type -> Type) -> Id -> Id
updateIdTypeAndMult Type -> Type
tidyTopType (Id -> Id
globaliseId Id
id)
                   Id -> Unfolding -> Id
`setIdUnfolding` Unfolding
BootUnfolding

{-
************************************************************************
*                                                                      *
        Plan B: tidy bindings, make TypeEnv full of IdInfo
*                                                                      *
************************************************************************

Plan B: include pragmas, make interfaces
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
* Step 1: Figure out which Ids are externally visible
          See Note [Choosing external Ids]

* Step 2: Gather the externally visible rules, separately from
          the top-level bindings.
          See Note [Finding external rules]

* Step 3: Tidy the bindings, externalising appropriate Ids
          See Note [Tidy the top-level bindings]

* Drop all Ids from the TypeEnv, and add all the External Ids from
  the bindings.  (This adds their IdInfo to the TypeEnv; and adds
  floated-out Ids that weren't even in the TypeEnv before.)

Note [Choosing external Ids]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~
See also the section "Interface stability" in the
recompilation-avoidance commentary:
  https://gitlab.haskell.org/ghc/ghc/wikis/commentary/compiler/recompilation-avoidance

First we figure out which Ids are "external" Ids.  An
"external" Id is one that is visible from outside the compilation
unit.  These are
  a) the user exported ones
  b) the ones bound to static forms
  c) ones mentioned in the unfoldings, workers, or
     rules of externally-visible ones

While figuring out which Ids are external, we pick a "tidy" OccName
for each one.  That is, we make its OccName distinct from the other
external OccNames in this module, so that in interface files and
object code we can refer to it unambiguously by its OccName.  The
OccName for each binder is prefixed by the name of the exported Id
that references it; e.g. if "f" references "x" in its unfolding, then
"x" is renamed to "f_x".  This helps distinguish the different "x"s
from each other, and means that if "f" is later removed, things that
depend on the other "x"s will not need to be recompiled.  Of course,
if there are multiple "f_x"s, then we have to disambiguate somehow; we
use "f_x0", "f_x1" etc.

As far as possible we should assign names in a deterministic fashion.
Each time this module is compiled with the same options, we should end
up with the same set of external names with the same types.  That is,
the ABI hash in the interface should not change.  This turns out to be
quite tricky, since the order of the bindings going into the tidy
phase is already non-deterministic, as it is based on the ordering of
Uniques, which are assigned unpredictably.

To name things in a stable way, we do a depth-first-search of the
bindings, starting from the exports sorted by name.  This way, as long
as the bindings themselves are deterministic (they sometimes aren't!),
the order in which they are presented to the tidying phase does not
affect the names we assign.

Note [Tidy the top-level bindings]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Next we traverse the bindings top to bottom.  For each *top-level*
binder

 1. Make it into a GlobalId; its IdDetails becomes VanillaGlobal,
    reflecting the fact that from now on we regard it as a global,
    not local, Id

 2. Give it a system-wide Unique.
    [Even non-exported things need system-wide Uniques because the
    byte-code generator builds a single Name->BCO symbol table.]

    We use the given NameCache as the source of such system-wide uniques.

    For external Ids, use the original-name cache in the NameCache
    to ensure that the unique assigned is the same as the Id had
    in any previous compilation run.

 3. Rename top-level Ids according to the names we chose in step 1.
    If it's an external Id, make it have a External Name, otherwise
    make it have an Internal Name.  This is used by the code generator
    to decide whether to make the label externally visible

 4. Give it its UTTERLY FINAL IdInfo; in ptic,
        * its unfolding, if it should have one

        * its arity, computed from the number of visible lambdas


Finally, substitute these new top-level binders consistently
throughout, including in unfoldings.  We also tidy binders in
RHSs, so that they print nicely in interfaces.

Note [Always expose compulsory unfoldings]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
We must make absolutely sure that unsafeCoerce# is inlined. You might
think that giving it a compulsory unfolding is enough. However,
unsafeCoerce# is put in an interface file just like any other definition.
So, unless we take special precuations
- If we compiled Unsafe.Coerce with -O0, we might not put the unfolding
  into the interface file.
- If we compile a module M, that imports Unsafe.Coerce, with -O0 we might
  not read the unfolding out of the interface file.

So we need to take care, to ensure that Compulsory unfoldings are written
and read.  That makes sense: they are compulsory, after all. There are
three places this is actioned:

* GHC.Iface.Tidy.addExternal.  Export end: expose compulsory
  unfoldings, even with -O0.

* GHC.IfaceToCore.tcIdInfo.  Import end: when reading in from
  interface file, even with -O0 (fignore-interface-pragmas.)  we must
  load a compulsory unfolding
-}

data UnfoldingExposure
  = ExposeNone -- ^ Don't expose unfoldings
  | ExposeSome -- ^ Expose mandatory unfoldings and those meeting inlining thresholds.
  | ExposeOverloaded -- ^ Expose unfoldings useful for inlinings and those which
                     -- which might be specialised. See Note [Exposing overloaded functions]
  | ExposeAll  -- ^ Expose all unfoldings
  deriving (Arity -> UnfoldingExposure -> ShowS
[UnfoldingExposure] -> ShowS
UnfoldingExposure -> String
(Arity -> UnfoldingExposure -> ShowS)
-> (UnfoldingExposure -> String)
-> ([UnfoldingExposure] -> ShowS)
-> Show UnfoldingExposure
forall a.
(Arity -> a -> ShowS) -> (a -> String) -> ([a] -> ShowS) -> Show a
$cshowsPrec :: Arity -> UnfoldingExposure -> ShowS
showsPrec :: Arity -> UnfoldingExposure -> ShowS
$cshow :: UnfoldingExposure -> String
show :: UnfoldingExposure -> String
$cshowList :: [UnfoldingExposure] -> ShowS
showList :: [UnfoldingExposure] -> ShowS
Show,UnfoldingExposure -> UnfoldingExposure -> Bool
(UnfoldingExposure -> UnfoldingExposure -> Bool)
-> (UnfoldingExposure -> UnfoldingExposure -> Bool)
-> Eq UnfoldingExposure
forall a. (a -> a -> Bool) -> (a -> a -> Bool) -> Eq a
$c== :: UnfoldingExposure -> UnfoldingExposure -> Bool
== :: UnfoldingExposure -> UnfoldingExposure -> Bool
$c/= :: UnfoldingExposure -> UnfoldingExposure -> Bool
/= :: UnfoldingExposure -> UnfoldingExposure -> Bool
Eq,Eq UnfoldingExposure
Eq UnfoldingExposure =>
(UnfoldingExposure -> UnfoldingExposure -> Ordering)
-> (UnfoldingExposure -> UnfoldingExposure -> Bool)
-> (UnfoldingExposure -> UnfoldingExposure -> Bool)
-> (UnfoldingExposure -> UnfoldingExposure -> Bool)
-> (UnfoldingExposure -> UnfoldingExposure -> Bool)
-> (UnfoldingExposure -> UnfoldingExposure -> UnfoldingExposure)
-> (UnfoldingExposure -> UnfoldingExposure -> UnfoldingExposure)
-> Ord UnfoldingExposure
UnfoldingExposure -> UnfoldingExposure -> Bool
UnfoldingExposure -> UnfoldingExposure -> Ordering
UnfoldingExposure -> UnfoldingExposure -> UnfoldingExposure
forall a.
Eq a =>
(a -> a -> Ordering)
-> (a -> a -> Bool)
-> (a -> a -> Bool)
-> (a -> a -> Bool)
-> (a -> a -> Bool)
-> (a -> a -> a)
-> (a -> a -> a)
-> Ord a
$ccompare :: UnfoldingExposure -> UnfoldingExposure -> Ordering
compare :: UnfoldingExposure -> UnfoldingExposure -> Ordering
$c< :: UnfoldingExposure -> UnfoldingExposure -> Bool
< :: UnfoldingExposure -> UnfoldingExposure -> Bool
$c<= :: UnfoldingExposure -> UnfoldingExposure -> Bool
<= :: UnfoldingExposure -> UnfoldingExposure -> Bool
$c> :: UnfoldingExposure -> UnfoldingExposure -> Bool
> :: UnfoldingExposure -> UnfoldingExposure -> Bool
$c>= :: UnfoldingExposure -> UnfoldingExposure -> Bool
>= :: UnfoldingExposure -> UnfoldingExposure -> Bool
$cmax :: UnfoldingExposure -> UnfoldingExposure -> UnfoldingExposure
max :: UnfoldingExposure -> UnfoldingExposure -> UnfoldingExposure
$cmin :: UnfoldingExposure -> UnfoldingExposure -> UnfoldingExposure
min :: UnfoldingExposure -> UnfoldingExposure -> UnfoldingExposure
Ord)

data TidyOpts = TidyOpts
  { TidyOpts -> NameCache
opt_name_cache        :: !NameCache
  , TidyOpts -> Bool
opt_collect_ccs       :: !Bool -- ^ Always true if we compile with -prof
  , TidyOpts -> UnfoldingOpts
opt_unfolding_opts    :: !UnfoldingOpts
  , TidyOpts -> UnfoldingExposure
opt_expose_unfoldings :: !UnfoldingExposure
      -- ^ Which unfoldings to expose
  , TidyOpts -> Bool
opt_trim_ids :: !Bool
      -- ^ trim off the arity, one-shot-ness, strictness etc which were
      -- retained for the benefit of the code generator
  , TidyOpts -> Bool
opt_expose_rules :: !Bool
      -- ^ Are rules exposed or not?
  , TidyOpts -> Maybe StaticPtrOpts
opt_static_ptr_opts :: !(Maybe StaticPtrOpts)
      -- ^ Options for generated static pointers, if enabled (/= Nothing).
  , TidyOpts -> Bool
opt_keep_auto_rules :: !Bool
  }

tidyProgram :: TidyOpts -> ModGuts -> IO (CgGuts, ModDetails)
tidyProgram :: TidyOpts -> ModGuts -> IO (CgGuts, ModDetails)
tidyProgram TidyOpts
opts (ModGuts { mg_module :: ModGuts -> Module
mg_module           = Module
mod
                          , mg_exports :: ModGuts -> [AvailInfo]
mg_exports          = [AvailInfo]
exports
                          , mg_tcs :: ModGuts -> [TyCon]
mg_tcs              = [TyCon]
tcs
                          , mg_defaults :: ModGuts -> DefaultEnv
mg_defaults         = DefaultEnv
cls_defaults
                          , mg_insts :: ModGuts -> [ClsInst]
mg_insts            = [ClsInst]
cls_insts
                          , mg_fam_insts :: ModGuts -> [FamInst]
mg_fam_insts        = [FamInst]
fam_insts
                          , mg_binds :: ModGuts -> CoreProgram
mg_binds            = CoreProgram
binds
                          , mg_patsyns :: ModGuts -> [PatSyn]
mg_patsyns          = [PatSyn]
patsyns
                          , mg_rules :: ModGuts -> [CoreRule]
mg_rules            = [CoreRule]
imp_rules
                          , mg_anns :: ModGuts -> [Annotation]
mg_anns             = [Annotation]
anns
                          , mg_complete_matches :: ModGuts -> CompleteMatches
mg_complete_matches = CompleteMatches
complete_matches
                          , mg_deps :: ModGuts -> Dependencies
mg_deps             = Dependencies
deps
                          , mg_foreign :: ModGuts -> ForeignStubs
mg_foreign          = ForeignStubs
foreign_stubs
                          , mg_foreign_files :: ModGuts -> [(ForeignSrcLang, String)]
mg_foreign_files    = [(ForeignSrcLang, String)]
foreign_files
                          , mg_hpc_info :: ModGuts -> HpcInfo
mg_hpc_info         = HpcInfo
hpc_info
                          , mg_modBreaks :: ModGuts -> Maybe ModBreaks
mg_modBreaks        = Maybe ModBreaks
modBreaks
                          , mg_boot_exports :: ModGuts -> NameSet
mg_boot_exports     = NameSet
boot_exports
                          }) = do

  let implicit_binds :: CoreProgram
implicit_binds = (TyCon -> CoreProgram) -> [TyCon] -> CoreProgram
forall (t :: * -> *) a b. Foldable t => (a -> [b]) -> t a -> [b]
concatMap TyCon -> CoreProgram
getImplicitBinds [TyCon]
tcs
      all_binds :: CoreProgram
all_binds = CoreProgram
implicit_binds CoreProgram -> CoreProgram -> CoreProgram
forall a. [a] -> [a] -> [a]
++ CoreProgram
binds

  (unfold_env, tidy_occ_env) <- TidyOpts
-> Module
-> CoreProgram
-> [CoreRule]
-> IO (UnfoldEnv, TidyOccEnv)
chooseExternalIds TidyOpts
opts Module
mod CoreProgram
all_binds [CoreRule]
imp_rules
  let (trimmed_binds, trimmed_rules) = findExternalRules opts all_binds imp_rules unfold_env

  (tidy_env, tidy_binds) <- tidyTopBinds unfold_env boot_exports tidy_occ_env trimmed_binds

  -- See Note [Grand plan for static forms] in GHC.Iface.Tidy.StaticPtrTable.
  (spt_entries, mcstub, tidy_binds') <- case opt_static_ptr_opts opts of
    Maybe StaticPtrOpts
Nothing    -> ([SptEntry], Maybe CStub, CoreProgram)
-> IO ([SptEntry], Maybe CStub, CoreProgram)
forall a. a -> IO a
forall (f :: * -> *) a. Applicative f => a -> f a
pure ([], Maybe CStub
forall a. Maybe a
Nothing, CoreProgram
tidy_binds)
    Just StaticPtrOpts
sopts -> StaticPtrOpts
-> Module
-> CoreProgram
-> IO ([SptEntry], Maybe CStub, CoreProgram)
sptCreateStaticBinds StaticPtrOpts
sopts Module
mod CoreProgram
tidy_binds

  -- pprTraceM "trimmed_rules" (ppr trimmed_rules)

  let all_foreign_stubs = case Maybe CStub
mcstub of
        Maybe CStub
Nothing    -> ForeignStubs
foreign_stubs
        Just CStub
cstub -> ForeignStubs
foreign_stubs ForeignStubs -> CStub -> ForeignStubs
`appendStubC` CStub
cstub

      -- The completed type environment is gotten from
      --      a) the types and classes defined here (plus implicit things)
      --      b) adding Ids with correct IdInfo, including unfoldings,
      --              gotten from the bindings
      -- From (b) we keep only those Ids with External names;
      --          the CoreTidy pass makes sure these are all and only
      --          the externally-accessible ones
      -- This truncates the type environment to include only the
      -- exported Ids and things needed from them, which saves space
      --
      -- See Note [Don't attempt to trim data types]
      final_ids  = [ Bool -> Id -> Id
trimId (TidyOpts -> Bool
opt_trim_ids TidyOpts
opts) Id
id
                   | Id
id <- CoreProgram -> [Id]
forall b. [Bind b] -> [b]
bindersOfBinds CoreProgram
tidy_binds
                   , Name -> Bool
isExternalName (Id -> Name
idName Id
id)
                   , Bool -> Bool
not (Id -> Bool
forall thing. NamedThing thing => thing -> Bool
isWiredIn Id
id)
                   ]   -- See Note [Drop wired-in things]

      final_tcs      = (TyCon -> Bool) -> [TyCon] -> [TyCon]
forall a. (a -> Bool) -> [a] -> [a]
filterOut TyCon -> Bool
forall thing. NamedThing thing => thing -> Bool
isWiredIn [TyCon]
tcs
                       -- See Note [Drop wired-in things]
      tidy_type_env  = [Id] -> [TyCon] -> [PatSyn] -> [FamInst] -> TypeEnv
typeEnvFromEntities [Id]
final_ids [TyCon]
final_tcs [PatSyn]
patsyns [FamInst]
fam_insts
      tidy_cls_insts = TypeEnv -> InstEnv -> InstEnv
mkFinalClsInsts TypeEnv
tidy_type_env (InstEnv -> InstEnv) -> InstEnv -> InstEnv
forall a b. (a -> b) -> a -> b
$ [ClsInst] -> InstEnv
mkInstEnv [ClsInst]
cls_insts
      tidy_rules     = TidyEnv -> [CoreRule] -> [CoreRule]
tidyRules TidyEnv
tidy_env [CoreRule]
trimmed_rules

      -- See Note [Injecting implicit bindings]
      all_tidy_binds = CoreProgram
tidy_binds'

      -- Get the TyCons to generate code for.  Careful!  We must use
      -- the untidied TyCons here, because we need
      --  (a) implicit TyCons arising from types and classes defined
      --      in this module
      --  (b) wired-in TyCons, which are normally removed from the
      --      TypeEnv we put in the ModDetails
      --  (c) Constructors even if they are not exported (the
      --      tidied TypeEnv has trimmed these away)
      alg_tycons = (TyCon -> Bool) -> [TyCon] -> [TyCon]
forall a. (a -> Bool) -> [a] -> [a]
filter TyCon -> Bool
isAlgTyCon [TyCon]
tcs

      local_ccs
        | TidyOpts -> Bool
opt_collect_ccs TidyOpts
opts
              = Module -> CoreProgram -> [CoreRule] -> Set CostCentre
collectCostCentres Module
mod CoreProgram
all_tidy_binds [CoreRule]
tidy_rules
        | Bool
otherwise
              = Set CostCentre
forall a. Set a
S.empty

  return (CgGuts { cg_module        = mod
                 , cg_tycons        = alg_tycons
                 , cg_binds         = all_tidy_binds
                 , cg_ccs           = S.toList local_ccs
                 , cg_foreign       = all_foreign_stubs
                 , cg_foreign_files = foreign_files
                 , cg_dep_pkgs      = dep_direct_pkgs deps
                 , cg_hpc_info      = hpc_info
                 , cg_modBreaks     = modBreaks
                 , cg_spt_entries   = spt_entries
                 }
         , ModDetails { md_types            = tidy_type_env
                      , md_rules            = tidy_rules
                      , md_defaults         = cls_defaults
                      , md_insts            = tidy_cls_insts
                      , md_fam_insts        = fam_insts
                      , md_exports          = exports
                      , md_anns             = anns      -- are already tidy
                      , md_complete_matches = complete_matches
                      }
         )


------------------------------------------------------------------------------
-- Collecting cost centres
-- ---------------------------------------------------------------------------

-- | Collect cost centres defined in the current module, including those in
-- unfoldings.
collectCostCentres :: Module -> CoreProgram -> [CoreRule] -> S.Set CostCentre
collectCostCentres :: Module -> CoreProgram -> [CoreRule] -> Set CostCentre
collectCostCentres Module
mod_name CoreProgram
binds [CoreRule]
rules
  = {-# SCC collectCostCentres #-} (Set CostCentre -> CoreBind -> Set CostCentre)
-> Set CostCentre -> CoreProgram -> Set CostCentre
forall b a. (b -> a -> b) -> b -> [a] -> b
forall (t :: * -> *) b a.
Foldable t =>
(b -> a -> b) -> b -> t a -> b
foldl' Set CostCentre -> CoreBind -> Set CostCentre
go_bind (Set CostCentre -> Set CostCentre
go_rules Set CostCentre
forall a. Set a
S.empty) CoreProgram
binds
  where
    go :: Set CostCentre -> Expr Id -> Set CostCentre
go Set CostCentre
cs Expr Id
e = case Expr Id
e of
      Var{} -> Set CostCentre
cs
      Lit{} -> Set CostCentre
cs
      App Expr Id
e1 Expr Id
e2 -> Set CostCentre -> Expr Id -> Set CostCentre
go (Set CostCentre -> Expr Id -> Set CostCentre
go Set CostCentre
cs Expr Id
e1) Expr Id
e2
      Lam Id
_ Expr Id
e -> Set CostCentre -> Expr Id -> Set CostCentre
go Set CostCentre
cs Expr Id
e
      Let CoreBind
b Expr Id
e -> Set CostCentre -> Expr Id -> Set CostCentre
go (Set CostCentre -> CoreBind -> Set CostCentre
go_bind Set CostCentre
cs CoreBind
b) Expr Id
e
      Case Expr Id
scrt Id
_ Type
_ [Alt Id]
alts -> Set CostCentre -> [Alt Id] -> Set CostCentre
go_alts (Set CostCentre -> Expr Id -> Set CostCentre
go Set CostCentre
cs Expr Id
scrt) [Alt Id]
alts
      Cast Expr Id
e CoercionR
_ -> Set CostCentre -> Expr Id -> Set CostCentre
go Set CostCentre
cs Expr Id
e
      Tick (ProfNote CostCentre
cc Bool
_ Bool
_) Expr Id
e ->
        Set CostCentre -> Expr Id -> Set CostCentre
go (if CostCentre -> Module -> Bool
ccFromThisModule CostCentre
cc Module
mod_name then CostCentre -> Set CostCentre -> Set CostCentre
forall a. Ord a => a -> Set a -> Set a
S.insert CostCentre
cc Set CostCentre
cs else Set CostCentre
cs) Expr Id
e
      Tick GenTickish 'TickishPassCore
_ Expr Id
e -> Set CostCentre -> Expr Id -> Set CostCentre
go Set CostCentre
cs Expr Id
e
      Type{} -> Set CostCentre
cs
      Coercion{} -> Set CostCentre
cs

    go_alts :: Set CostCentre -> [Alt Id] -> Set CostCentre
go_alts = (Set CostCentre -> Alt Id -> Set CostCentre)
-> Set CostCentre -> [Alt Id] -> Set CostCentre
forall b a. (b -> a -> b) -> b -> [a] -> b
forall (t :: * -> *) b a.
Foldable t =>
(b -> a -> b) -> b -> t a -> b
foldl' (\Set CostCentre
cs (Alt AltCon
_con [Id]
_bndrs Expr Id
e) -> Set CostCentre -> Expr Id -> Set CostCentre
go Set CostCentre
cs Expr Id
e)

    go_bind :: S.Set CostCentre -> CoreBind -> S.Set CostCentre
    go_bind :: Set CostCentre -> CoreBind -> Set CostCentre
go_bind Set CostCentre
cs (NonRec Id
b Expr Id
e) =
      Set CostCentre -> Expr Id -> Set CostCentre
go (Set CostCentre -> Id -> Set CostCentre
do_binder Set CostCentre
cs Id
b) Expr Id
e
    go_bind Set CostCentre
cs (Rec [(Id, Expr Id)]
bs) =
      (Set CostCentre -> (Id, Expr Id) -> Set CostCentre)
-> Set CostCentre -> [(Id, Expr Id)] -> Set CostCentre
forall b a. (b -> a -> b) -> b -> [a] -> b
forall (t :: * -> *) b a.
Foldable t =>
(b -> a -> b) -> b -> t a -> b
foldl' (\Set CostCentre
cs' (Id
b, Expr Id
e) -> Set CostCentre -> Expr Id -> Set CostCentre
go (Set CostCentre -> Id -> Set CostCentre
do_binder Set CostCentre
cs' Id
b) Expr Id
e) Set CostCentre
cs [(Id, Expr Id)]
bs

    do_binder :: Set CostCentre -> Id -> Set CostCentre
do_binder Set CostCentre
cs Id
b = Set CostCentre
-> (Expr Id -> Set CostCentre) -> Maybe (Expr Id) -> Set CostCentre
forall b a. b -> (a -> b) -> Maybe a -> b
maybe Set CostCentre
cs (Set CostCentre -> Expr Id -> Set CostCentre
go Set CostCentre
cs) (Id -> Maybe (Expr Id)
get_unf Id
b)

    -- Unfoldings may have cost centres that in the original definion are
    -- optimized away, see #5889.
    get_unf :: Id -> Maybe (Expr Id)
get_unf = Unfolding -> Maybe (Expr Id)
maybeUnfoldingTemplate (Unfolding -> Maybe (Expr Id))
-> (Id -> Unfolding) -> Id -> Maybe (Expr Id)
forall b c a. (b -> c) -> (a -> b) -> a -> c
. Id -> Unfolding
realIdUnfolding

    -- Have to look at the RHS of rules as well, as these may contain ticks which
    -- don't appear anywhere else. See #19894
    go_rules :: Set CostCentre -> Set CostCentre
go_rules Set CostCentre
cs = (Set CostCentre -> Expr Id -> Set CostCentre)
-> Set CostCentre -> [Expr Id] -> Set CostCentre
forall b a. (b -> a -> b) -> b -> [a] -> b
forall (t :: * -> *) b a.
Foldable t =>
(b -> a -> b) -> b -> t a -> b
foldl' Set CostCentre -> Expr Id -> Set CostCentre
go Set CostCentre
cs ((CoreRule -> Maybe (Expr Id)) -> [CoreRule] -> [Expr Id]
forall a b. (a -> Maybe b) -> [a] -> [b]
mapMaybe CoreRule -> Maybe (Expr Id)
get_rhs [CoreRule]
rules)

    get_rhs :: CoreRule -> Maybe (Expr Id)
get_rhs Rule { Expr Id
ru_rhs :: Expr Id
ru_rhs :: CoreRule -> Expr Id
ru_rhs } = Expr Id -> Maybe (Expr Id)
forall a. a -> Maybe a
Just Expr Id
ru_rhs
    get_rhs BuiltinRule {} = Maybe (Expr Id)
forall a. Maybe a
Nothing

--------------------------
trimId :: Bool -> Id -> Id
-- With -O0 we now trim off the arity, one-shot-ness, strictness
-- etc which tidyTopIdInfo retains for the benefit of the code generator
-- but which we don't want in the interface file or ModIface for
-- downstream compilations
trimId :: Bool -> Id -> Id
trimId Bool
do_trim Id
id
  | Bool
do_trim, Bool -> Bool
not (Id -> Bool
isImplicitId Id
id)
  = Id
id Id -> IdInfo -> Id
`setIdInfo`      IdInfo
vanillaIdInfo
       Id -> Unfolding -> Id
`setIdUnfolding` Id -> Unfolding
idUnfolding Id
id
       -- We respect the final unfolding chosen by tidyTopIdInfo.
       -- We have already trimmed it if we don't want it for -O0;
       -- see also Note [Always expose compulsory unfoldings]

  | Bool
otherwise   -- No trimming
  = Id
id

{- Note [Drop wired-in things]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
We never put wired-in TyCons or Ids in an interface file.
They are wired-in, so the compiler knows about them already.

Note [Don't attempt to trim data types]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
For some time GHC tried to avoid exporting the data constructors
of a data type if it wasn't strictly necessary to do so; see #835.
But "strictly necessary" accumulated a longer and longer list
of exceptions, and finally I gave up the battle:

    commit 9a20e540754fc2af74c2e7392f2786a81d8d5f11
    Author: Simon Peyton Jones <simonpj@microsoft.com>
    Date:   Thu Dec 6 16:03:16 2012 +0000

    Stop attempting to "trim" data types in interface files

    Without -O, we previously tried to make interface files smaller
    by not including the data constructors of data types.  But
    there are a lot of exceptions, notably when Template Haskell is
    involved or, more recently, DataKinds.

    However #7445 shows that even without TemplateHaskell, using
    the Data class and invoking Language.Haskell.TH.Quote.dataToExpQ
    is enough to require us to expose the data constructors.

    So I've given up on this "optimisation" -- it's probably not
    important anyway.  Now I'm simply not attempting to trim off
    the data constructors.  The gain in simplicity is worth the
    modest cost in interface file growth, which is limited to the
    bits reqd to describe those data constructors.

************************************************************************
*                                                                      *
        Implicit bindings
*                                                                      *
************************************************************************

Note [Injecting implicit bindings]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
We inject the implicit bindings right at the end, in GHC.Core.Tidy.
Some of these bindings, notably record selectors, are not
constructed in an optimised form.  E.g. record selector for
        data T = MkT { x :: {-# UNPACK #-} !Int }
Then the unfolding looks like
        x = \t. case t of MkT x1 -> let x = I# x1 in x
This generates bad code unless it's first simplified a bit.  That is
why GHC.Core.Unfold.mkImplicitUnfolding uses simpleOptExpr to do a bit of
optimisation first.  (Only matters when the selector is used curried;
eg map x ys.)  See #2070.

[Oct 09: in fact, record selectors are no longer implicit Ids at all,
because we really do want to optimise them properly. They are treated
much like any other Id.  But doing "light" optimisation on an implicit
Id still makes sense.]

At one time I tried injecting the implicit bindings *early*, at the
beginning of SimplCore.  But that gave rise to real difficulty,
because GlobalIds are supposed to have *fixed* IdInfo, but the
simplifier and other core-to-core passes mess with IdInfo all the
time.  The straw that broke the camels back was when a class selector
got the wrong arity -- ie the simplifier gave it arity 2, whereas
importing modules were expecting it to have arity 1 (#2844).
It's much safer just to inject them right at the end, after tidying.

Oh: two other reasons for injecting them late:

  - If implicit Ids are already in the bindings when we start tidying,
    we'd have to be careful not to treat them as external Ids (in
    the sense of chooseExternalIds); else the Ids mentioned in *their*
    RHSs will be treated as external and you get an interface file
    saying      a18 = <blah>
    but nothing referring to a18 (because the implicit Id is the
    one that does, and implicit Ids don't appear in interface files).

  - More seriously, the tidied type-envt will include the implicit
    Id replete with a18 in its unfolding; but we won't take account
    of a18 when computing a fingerprint for the class; result chaos.

There is one sort of implicit binding that is injected still later,
namely those for data constructor workers. Reason (I think): it's
really just a code generation trick.... binding itself makes no sense.
See Note [Data constructor workers] in "GHC.CoreToStg.Prep".
-}

getImplicitBinds :: TyCon -> [CoreBind]
getImplicitBinds :: TyCon -> CoreProgram
getImplicitBinds TyCon
tc = CoreProgram
cls_binds CoreProgram -> CoreProgram -> CoreProgram
forall a. [a] -> [a] -> [a]
++ TyCon -> CoreProgram
getTyConImplicitBinds TyCon
tc
  where
    cls_binds :: CoreProgram
cls_binds = CoreProgram -> (Class -> CoreProgram) -> Maybe Class -> CoreProgram
forall b a. b -> (a -> b) -> Maybe a -> b
maybe [] Class -> CoreProgram
getClassImplicitBinds (TyCon -> Maybe Class
tyConClass_maybe TyCon
tc)

getTyConImplicitBinds :: TyCon -> [CoreBind]
getTyConImplicitBinds :: TyCon -> CoreProgram
getTyConImplicitBinds TyCon
tc
  | TyCon -> Bool
isDataTyCon TyCon
tc = [ Id -> Expr Id -> CoreBind
forall b. b -> Expr b -> Bind b
NonRec Id
wrap_id Expr Id
rhs
                     | DataCon
dc <- TyCon -> [DataCon]
tyConDataCons TyCon
tc
                     , let wrap_id :: Id
wrap_id = DataCon -> Id
dataConWrapId DataCon
dc
                         -- For data cons with no wrapper, this wrap_id
                         -- is in fact a DataConWorkId, and hence
                         -- dataConWrapUnfolding_maybe returns Nothing
                     , Just Expr Id
rhs <- [Id -> Maybe (Expr Id)
dataConWrapUnfolding_maybe Id
wrap_id] ]

  | Bool
otherwise      = []
    -- The 'otherwise' includes family TyCons of course, but also (less obviously)
    --  * Newtypes: see Note [Compulsory newtype unfolding] in GHC.Types.Id.Make
    --  * type data: we don't want any code for type-only stuff (#24620)

getClassImplicitBinds :: Class -> [CoreBind]
getClassImplicitBinds :: Class -> CoreProgram
getClassImplicitBinds Class
cls
  = [ Id -> Expr Id -> CoreBind
forall b. b -> Expr b -> Bind b
NonRec Id
op (Class -> Arity -> Expr Id
mkDictSelRhs Class
cls Arity
val_index)
    | (Id
op, Arity
val_index) <- Class -> [Id]
classAllSelIds Class
cls [Id] -> [Arity] -> [(Id, Arity)]
forall a b. [a] -> [b] -> [(a, b)]
`zip` [Arity
0..] ]

{-
************************************************************************
*                                                                      *
\subsection{Step 1: finding externals}
*                                                                      *
************************************************************************

See Note [Choosing external Ids].
-}

type UnfoldEnv  = IdEnv (Name{-new name-}, Bool {-show unfolding-})
  -- Maps each top-level Id to its new Name (the Id is tidied in step 2)
  -- The Unique is unchanged.  If the new Name is external, it will be
  -- visible in the interface file.
  --
  -- Bool => expose unfolding or not.

chooseExternalIds :: TidyOpts
                  -> Module
                  -> [CoreBind]
                  -> [CoreRule]
                  -> IO (UnfoldEnv, TidyOccEnv)
                  -- Step 1 from the notes above

chooseExternalIds :: TidyOpts
-> Module
-> CoreProgram
-> [CoreRule]
-> IO (UnfoldEnv, TidyOccEnv)
chooseExternalIds TidyOpts
opts Module
mod CoreProgram
binds [CoreRule]
imp_id_rules
  = do { (unfold_env1,occ_env1) <- [(Id, Id)] -> UnfoldEnv -> TidyOccEnv -> IO (UnfoldEnv, TidyOccEnv)
search [(Id, Id)]
init_work_list UnfoldEnv
forall a. VarEnv a
emptyVarEnv TidyOccEnv
init_occ_env
       ; let internal_ids = (Id -> Bool) -> [Id] -> [Id]
forall a. (a -> Bool) -> [a] -> [a]
filter (Bool -> Bool
not (Bool -> Bool) -> (Id -> Bool) -> Id -> Bool
forall b c a. (b -> c) -> (a -> b) -> a -> c
. (Id -> UnfoldEnv -> Bool
forall a. Id -> VarEnv a -> Bool
`elemVarEnv` UnfoldEnv
unfold_env1)) [Id]
binders
       ; tidy_internal internal_ids unfold_env1 occ_env1 }
 where
  name_cache :: NameCache
name_cache = TidyOpts -> NameCache
opt_name_cache TidyOpts
opts

  -- init_ext_ids is the initial list of Ids that should be
  -- externalised.  It serves as the starting point for finding a
  -- deterministic, tidy, renaming for all external Ids in this
  -- module.
  --
  -- It is sorted, so that it has a deterministic order (i.e. it's the
  -- same list every time this module is compiled), in contrast to the
  -- bindings, which are ordered non-deterministically.
  init_work_list :: [(Id, Id)]
init_work_list = [Id] -> [Id] -> [(Id, Id)]
forall a b. [a] -> [b] -> [(a, b)]
zip [Id]
init_ext_ids [Id]
init_ext_ids
  init_ext_ids :: [Id]
init_ext_ids   = (Id -> Id -> Ordering) -> [Id] -> [Id]
forall a. (a -> a -> Ordering) -> [a] -> [a]
sortBy (OccName -> OccName -> Ordering
forall a. Ord a => a -> a -> Ordering
compare (OccName -> OccName -> Ordering)
-> (Id -> OccName) -> Id -> Id -> Ordering
forall b c a. (b -> b -> c) -> (a -> b) -> a -> a -> c
`on` Id -> OccName
forall a. NamedThing a => a -> OccName
getOccName) ([Id] -> [Id]) -> [Id] -> [Id]
forall a b. (a -> b) -> a -> b
$ (Id -> Bool) -> [Id] -> [Id]
forall a. (a -> Bool) -> [a] -> [a]
filter Id -> Bool
is_external [Id]
binders

  -- An Id should be external if either (a) it is exported,
  -- (b) local rules are exposed and it appears in the RHS of a local rule for
  -- an imported Id, or See Note [Which rules to expose]
  is_external :: Id -> Bool
is_external Id
id
    | Id -> Bool
isExportedId Id
id       = Bool
True
    | TidyOpts -> Bool
opt_expose_rules TidyOpts
opts = Id
id Id -> VarSet -> Bool
`elemVarSet` VarSet
rule_rhs_vars
    | Bool
otherwise             = Bool
False

  rule_rhs_vars :: VarSet
rule_rhs_vars = (CoreRule -> VarSet) -> [CoreRule] -> VarSet
forall a. (a -> VarSet) -> [a] -> VarSet
mapUnionVarSet CoreRule -> VarSet
ruleRhsFreeVars [CoreRule]
imp_id_rules

  binders :: [Id]
binders          = ((Id, Expr Id) -> Id) -> [(Id, Expr Id)] -> [Id]
forall a b. (a -> b) -> [a] -> [b]
map (Id, Expr Id) -> Id
forall a b. (a, b) -> a
fst ([(Id, Expr Id)] -> [Id]) -> [(Id, Expr Id)] -> [Id]
forall a b. (a -> b) -> a -> b
$ CoreProgram -> [(Id, Expr Id)]
forall b. [Bind b] -> [(b, Expr b)]
flattenBinds CoreProgram
binds
  binder_set :: VarSet
binder_set       = [Id] -> VarSet
mkVarSet [Id]
binders

  avoids :: [OccName]
avoids   = [Name -> OccName
forall a. NamedThing a => a -> OccName
getOccName Name
name | Id
bndr <- [Id]
binders,
                                let name :: Name
name = Id -> Name
idName Id
bndr,
                                Name -> Bool
isExternalName Name
name ]
                -- In computing our "avoids" list, we must include
                --      all implicit Ids
                --      all things with global names (assigned once and for
                --                                      all by the renamer)
                -- since their names are "taken".
                -- The type environment is a convenient source of such things.
                -- In particular, the set of binders doesn't include
                -- implicit Ids at this stage.

        -- We also make sure to avoid any exported binders.  Consider
        --      f{-u1-} = 1     -- Local decl
        --      ...
        --      f{-u2-} = 2     -- Exported decl
        --
        -- The second exported decl must 'get' the name 'f', so we
        -- have to put 'f' in the avoids list before we get to the first
        -- decl.  tidyTopId then does a no-op on exported binders.
  init_occ_env :: TidyOccEnv
init_occ_env = [OccName] -> TidyOccEnv
initTidyOccEnv [OccName]
avoids


  search :: [(Id,Id)]    -- The work-list: (external id, referring id)
                         -- Make a tidy, external Name for the external id,
                         --   add it to the UnfoldEnv, and do the same for the
                         --   transitive closure of Ids it refers to
                         -- The referring id is used to generate a tidy
                         ---  name for the external id
         -> UnfoldEnv    -- id -> (new Name, show_unfold)
         -> TidyOccEnv   -- occ env for choosing new Names
         -> IO (UnfoldEnv, TidyOccEnv)

  search :: [(Id, Id)] -> UnfoldEnv -> TidyOccEnv -> IO (UnfoldEnv, TidyOccEnv)
search [] UnfoldEnv
unfold_env TidyOccEnv
occ_env = (UnfoldEnv, TidyOccEnv) -> IO (UnfoldEnv, TidyOccEnv)
forall a. a -> IO a
forall (m :: * -> *) a. Monad m => a -> m a
return (UnfoldEnv
unfold_env, TidyOccEnv
occ_env)

  search ((Id
idocc,Id
referrer) : [(Id, Id)]
rest) UnfoldEnv
unfold_env TidyOccEnv
occ_env
    | Id
idocc Id -> UnfoldEnv -> Bool
forall a. Id -> VarEnv a -> Bool
`elemVarEnv` UnfoldEnv
unfold_env = [(Id, Id)] -> UnfoldEnv -> TidyOccEnv -> IO (UnfoldEnv, TidyOccEnv)
search [(Id, Id)]
rest UnfoldEnv
unfold_env TidyOccEnv
occ_env
    | Bool
otherwise = do
      (occ_env', name') <- Module
-> NameCache
-> Maybe Id
-> TidyOccEnv
-> Id
-> IO (TidyOccEnv, Name)
tidyTopName Module
mod NameCache
name_cache (Id -> Maybe Id
forall a. a -> Maybe a
Just Id
referrer) TidyOccEnv
occ_env Id
idocc
      let
          (new_ids, show_unfold) = addExternal opts refined_id

                -- 'idocc' is an *occurrence*, but we need to see the
                -- unfolding in the *definition*; so look up in binder_set
          refined_id = case VarSet -> Id -> Maybe Id
lookupVarSet VarSet
binder_set Id
idocc of
                         Just Id
id -> Id
id
                         Maybe Id
Nothing -> Bool -> String -> SDoc -> Id -> Id
forall a. HasCallStack => Bool -> String -> SDoc -> a -> a
warnPprTrace Bool
True String
"chooseExternalIds" (Id -> SDoc
forall a. Outputable a => a -> SDoc
ppr Id
idocc) Id
idocc

          unfold_env' = UnfoldEnv -> Id -> (Name, Bool) -> UnfoldEnv
forall a. VarEnv a -> Id -> a -> VarEnv a
extendVarEnv UnfoldEnv
unfold_env Id
idocc (Name
name',Bool
show_unfold)
          referrer' | Id -> Bool
isExportedId Id
refined_id = Id
refined_id
                    | Bool
otherwise               = Id
referrer
      --
      search (zip new_ids (repeat referrer') ++ rest) unfold_env' occ_env'

  tidy_internal :: [Id] -> UnfoldEnv -> TidyOccEnv
                -> IO (UnfoldEnv, TidyOccEnv)
  tidy_internal :: [Id] -> UnfoldEnv -> TidyOccEnv -> IO (UnfoldEnv, TidyOccEnv)
tidy_internal []       UnfoldEnv
unfold_env TidyOccEnv
occ_env = (UnfoldEnv, TidyOccEnv) -> IO (UnfoldEnv, TidyOccEnv)
forall a. a -> IO a
forall (m :: * -> *) a. Monad m => a -> m a
return (UnfoldEnv
unfold_env,TidyOccEnv
occ_env)
  tidy_internal (Id
id:[Id]
ids) UnfoldEnv
unfold_env TidyOccEnv
occ_env = do
      (occ_env', name') <- Module
-> NameCache
-> Maybe Id
-> TidyOccEnv
-> Id
-> IO (TidyOccEnv, Name)
tidyTopName Module
mod NameCache
name_cache Maybe Id
forall a. Maybe a
Nothing TidyOccEnv
occ_env Id
id
      let unfold_env' = UnfoldEnv -> Id -> (Name, Bool) -> UnfoldEnv
forall a. VarEnv a -> Id -> a -> VarEnv a
extendVarEnv UnfoldEnv
unfold_env Id
id (Name
name',Bool
False)
      tidy_internal ids unfold_env' occ_env'

addExternal :: TidyOpts -> Id -> ([Id], Bool)
addExternal :: TidyOpts -> Id -> ([Id], Bool)
addExternal TidyOpts
opts Id
id
  | UnfoldingExposure
ExposeNone <- TidyOpts -> UnfoldingExposure
opt_expose_unfoldings TidyOpts
opts
  , Bool -> Bool
not (Unfolding -> Bool
isCompulsoryUnfolding Unfolding
unfolding)
  = ([], Bool
False)  -- See Note [Always expose compulsory unfoldings]
                 -- in GHC.HsToCore

  | Bool
otherwise
  = ([Id]
new_needed_ids, Bool
show_unfold)

  where
    new_needed_ids :: [Id]
new_needed_ids = Bool -> Id -> [Id]
bndrFvsInOrder Bool
show_unfold Id
id
    idinfo :: IdInfo
idinfo         = HasDebugCallStack => Id -> IdInfo
Id -> IdInfo
idInfo Id
id
    unfolding :: Unfolding
unfolding      = IdInfo -> Unfolding
realUnfoldingInfo IdInfo
idinfo
    show_unfold :: Bool
show_unfold    = Unfolding -> Bool
show_unfolding Unfolding
unfolding
    never_active :: Bool
never_active   = Activation -> Bool
isNeverActive (InlinePragma -> Activation
inlinePragmaActivation (IdInfo -> InlinePragma
inlinePragInfo IdInfo
idinfo))
    loop_breaker :: Bool
loop_breaker   = OccInfo -> Bool
isStrongLoopBreaker (IdInfo -> OccInfo
occInfo IdInfo
idinfo)
    -- bottoming_fn: don't inline bottoming functions, unless the
    -- RHS is very small or trivial (UnfWhen), in which case we
    -- may as well do so. For example, a cast might cancel with
    -- the call site.
    bottoming_fn :: Bool
bottoming_fn   = DmdSig -> Bool
isDeadEndSig (IdInfo -> DmdSig
dmdSigInfo IdInfo
idinfo)

        -- Stuff to do with the Id's unfolding
        -- We leave the unfolding there even if there is a worker
        -- In GHCi the unfolding is used by importers

    show_unfolding :: Unfolding -> Bool
show_unfolding (CoreUnfolding { uf_src :: Unfolding -> UnfoldingSource
uf_src = UnfoldingSource
src, uf_guidance :: Unfolding -> UnfoldingGuidance
uf_guidance = UnfoldingGuidance
guidance })
       = Bool
stable Bool -> Bool -> Bool
|| Bool
profitable Bool -> Bool -> Bool
|| Bool
explicitly_requested
       where
        -- Always expose things whose
        -- source is an inline rule
        stable :: Bool
stable = UnfoldingSource -> Bool
isStableSource UnfoldingSource
src
        -- Good for perf as it might inline
        profitable :: Bool
profitable
          | Bool
never_active = Bool
False
          | Bool
loop_breaker = Bool
False
          | Bool
otherwise =
              case UnfoldingGuidance
guidance of
                UnfWhen {}  -> Bool
True
                UnfIfGoodArgs {} -> Bool -> Bool
not Bool
bottoming_fn
                UnfoldingGuidance
UnfNever -> Bool
False
        -- Requested by the user through a flag.
        explicitly_requested :: Bool
explicitly_requested =
          case TidyOpts -> UnfoldingExposure
opt_expose_unfoldings TidyOpts
opts of
            -- 'ExposeAll' says to expose all
            -- unfoldings willy-nilly
            UnfoldingExposure
ExposeAll -> Bool
True
            -- Overloaded functions like @foo :: Bar a => ...@
            -- See Note [Exposing overloaded functions]
            UnfoldingExposure
ExposeOverloaded ->
              Bool -> Bool
not Bool
bottoming_fn Bool -> Bool -> Bool
&& Id -> Bool
isOverloaded Id
id
            UnfoldingExposure
ExposeSome -> Bool
False
            UnfoldingExposure
ExposeNone -> Bool
False

    show_unfolding (DFunUnfolding {}) = Bool
True
    show_unfolding Unfolding
_                  = Bool
False

isOverloaded :: Id -> Bool
isOverloaded :: Id -> Bool
isOverloaded Id
fn =
  let fun_type :: Type
fun_type = Id -> Type
idType Id
fn
      -- TODO: The specialiser currently doesn't handle newtypes of the
      -- form `newtype T x = T (C x => x)` well. So we don't bother
      -- looking through newtypes for constraints.
      -- (Newtypes are opaque to tcSplitNestedSigmaTys)
      -- If the specialiser ever starts looking through newtypes properly
      -- we might want to use a version of tcSplitNestedSigmaTys that looks
      -- through newtypes.
      ([Id]
_ty_vars, ThetaType
constraints, Type
_ty) = Type -> ([Id], ThetaType, Type)
tcSplitNestedSigmaTys Type
fun_type
      -- NB: This will consider functions with only equality constraints overloaded.
      -- While these sorts of constraints aren't currently useful for specialization
      -- it's simpler to just include them.
  in Bool -> Bool
not (Bool -> Bool) -> (ThetaType -> Bool) -> ThetaType -> Bool
forall b c a. (b -> c) -> (a -> b) -> a -> c
. ThetaType -> Bool
forall a. [a] -> Bool
forall (t :: * -> *) a. Foldable t => t a -> Bool
null (ThetaType -> Bool) -> ThetaType -> Bool
forall a b. (a -> b) -> a -> b
$ ThetaType
constraints

{- Note [Exposing overloaded functions]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
See also #13090 and #22942.

The basic idea is that exposing only overloaded function is reasonably cheap
but allows the specializer to fire more often as unfoldings for overloaded
functions will generally be available. So we make the unfoldings of overloaded
functions available when `-fexpose-overloaded-unfoldings is enabled.

We use `tcSplitNestedSigmaTys` to see the constraints deep within in types like:
  f :: Int -> forall a. Eq a => blah

We could simply use isClassPred to check if any of the constraints responds to
a class dictionary, but that would miss (perhaps obscure) opportunities
like the one in the program below:

    type family C a where
      C Int = Eq Int
      C Bool = Ord Bool


    bar :: C a => a -> a -> Bool
    bar = undefined
    {-# SPECIALIZE bar :: Int -> Int -> Bool #-}

GHC will specialize `bar` properly. However `C a =>` isn't recognized as class
predicate since it's a type family in the definition. To ensure it's exposed
anyway we allow for some false positives and simply expose all functions which
have a constraint. This means we might expose more unhelpful unfoldings. But
it seems like the better choice.

Currently this option is off by default and has to be enabled manually. But
we might change this in the future.
-}

{-
************************************************************************
*                                                                      *
               Deterministic free variables
*                                                                      *
************************************************************************

We want a deterministic free-variable list.  exprFreeVars gives us
a VarSet, which is in a non-deterministic order when converted to a
list.  Hence, here we define a free-variable finder that returns
the free variables in the order that they are encountered.

See Note [Choosing external Ids]
-}

bndrFvsInOrder :: Bool -> Id -> [Id]
bndrFvsInOrder :: Bool -> Id -> [Id]
bndrFvsInOrder Bool
show_unfold Id
id
  = DFFV () -> [Id]
run (Bool -> Id -> DFFV ()
dffvLetBndr Bool
show_unfold Id
id)

run :: DFFV () -> [Id]
run :: DFFV () -> [Id]
run (DFFV VarSet -> (VarSet, [Id]) -> ((VarSet, [Id]), ())
m) = case VarSet -> (VarSet, [Id]) -> ((VarSet, [Id]), ())
m VarSet
emptyVarSet (VarSet
emptyVarSet, []) of
                 ((VarSet
_,[Id]
ids),()
_) -> [Id]
ids

newtype DFFV a
  = DFFV (VarSet              -- Envt: non-top-level things that are in scope
                              -- we don't want to record these as free vars
      -> (VarSet, [Var])      -- Input State: (set, list) of free vars so far
      -> ((VarSet,[Var]),a))  -- Output state
    deriving ((forall a b. (a -> b) -> DFFV a -> DFFV b)
-> (forall a b. a -> DFFV b -> DFFV a) -> Functor DFFV
forall a b. a -> DFFV b -> DFFV a
forall a b. (a -> b) -> DFFV a -> DFFV b
forall (f :: * -> *).
(forall a b. (a -> b) -> f a -> f b)
-> (forall a b. a -> f b -> f a) -> Functor f
$cfmap :: forall a b. (a -> b) -> DFFV a -> DFFV b
fmap :: forall a b. (a -> b) -> DFFV a -> DFFV b
$c<$ :: forall a b. a -> DFFV b -> DFFV a
<$ :: forall a b. a -> DFFV b -> DFFV a
Functor)

instance Applicative DFFV where
    pure :: forall a. a -> DFFV a
pure a
a = (VarSet -> (VarSet, [Id]) -> ((VarSet, [Id]), a)) -> DFFV a
forall a.
(VarSet -> (VarSet, [Id]) -> ((VarSet, [Id]), a)) -> DFFV a
DFFV ((VarSet -> (VarSet, [Id]) -> ((VarSet, [Id]), a)) -> DFFV a)
-> (VarSet -> (VarSet, [Id]) -> ((VarSet, [Id]), a)) -> DFFV a
forall a b. (a -> b) -> a -> b
$ \VarSet
_ (VarSet, [Id])
st -> ((VarSet, [Id])
st, a
a)
    <*> :: forall a b. DFFV (a -> b) -> DFFV a -> DFFV b
(<*>) = DFFV (a -> b) -> DFFV a -> DFFV b
forall (m :: * -> *) a b. Monad m => m (a -> b) -> m a -> m b
ap

instance Monad DFFV where
  (DFFV VarSet -> (VarSet, [Id]) -> ((VarSet, [Id]), a)
m) >>= :: forall a b. DFFV a -> (a -> DFFV b) -> DFFV b
>>= a -> DFFV b
k = (VarSet -> (VarSet, [Id]) -> ((VarSet, [Id]), b)) -> DFFV b
forall a.
(VarSet -> (VarSet, [Id]) -> ((VarSet, [Id]), a)) -> DFFV a
DFFV ((VarSet -> (VarSet, [Id]) -> ((VarSet, [Id]), b)) -> DFFV b)
-> (VarSet -> (VarSet, [Id]) -> ((VarSet, [Id]), b)) -> DFFV b
forall a b. (a -> b) -> a -> b
$ \VarSet
env (VarSet, [Id])
st ->
    case VarSet -> (VarSet, [Id]) -> ((VarSet, [Id]), a)
m VarSet
env (VarSet, [Id])
st of
       ((VarSet, [Id])
st',a
a) -> case a -> DFFV b
k a
a of
                     DFFV VarSet -> (VarSet, [Id]) -> ((VarSet, [Id]), b)
f -> VarSet -> (VarSet, [Id]) -> ((VarSet, [Id]), b)
f VarSet
env (VarSet, [Id])
st'

extendScope :: Var -> DFFV a -> DFFV a
extendScope :: forall a. Id -> DFFV a -> DFFV a
extendScope Id
v (DFFV VarSet -> (VarSet, [Id]) -> ((VarSet, [Id]), a)
f) = (VarSet -> (VarSet, [Id]) -> ((VarSet, [Id]), a)) -> DFFV a
forall a.
(VarSet -> (VarSet, [Id]) -> ((VarSet, [Id]), a)) -> DFFV a
DFFV (\VarSet
env (VarSet, [Id])
st -> VarSet -> (VarSet, [Id]) -> ((VarSet, [Id]), a)
f (VarSet -> Id -> VarSet
extendVarSet VarSet
env Id
v) (VarSet, [Id])
st)

extendScopeList :: [Var] -> DFFV a -> DFFV a
extendScopeList :: forall a. [Id] -> DFFV a -> DFFV a
extendScopeList [Id]
vs (DFFV VarSet -> (VarSet, [Id]) -> ((VarSet, [Id]), a)
f) = (VarSet -> (VarSet, [Id]) -> ((VarSet, [Id]), a)) -> DFFV a
forall a.
(VarSet -> (VarSet, [Id]) -> ((VarSet, [Id]), a)) -> DFFV a
DFFV (\VarSet
env (VarSet, [Id])
st -> VarSet -> (VarSet, [Id]) -> ((VarSet, [Id]), a)
f (VarSet -> [Id] -> VarSet
extendVarSetList VarSet
env [Id]
vs) (VarSet, [Id])
st)

insert :: Var -> DFFV ()
insert :: Id -> DFFV ()
insert Id
v = (VarSet -> (VarSet, [Id]) -> ((VarSet, [Id]), ())) -> DFFV ()
forall a.
(VarSet -> (VarSet, [Id]) -> ((VarSet, [Id]), a)) -> DFFV a
DFFV ((VarSet -> (VarSet, [Id]) -> ((VarSet, [Id]), ())) -> DFFV ())
-> (VarSet -> (VarSet, [Id]) -> ((VarSet, [Id]), ())) -> DFFV ()
forall a b. (a -> b) -> a -> b
$ \ VarSet
env (VarSet
set, [Id]
ids) ->
           let keep_me :: Bool
keep_me = Id -> Bool
isLocalId Id
v Bool -> Bool -> Bool
&&
                         Bool -> Bool
not (Id
v Id -> VarSet -> Bool
`elemVarSet` VarSet
env) Bool -> Bool -> Bool
&&
                           Bool -> Bool
not (Id
v Id -> VarSet -> Bool
`elemVarSet` VarSet
set)
           in if Bool
keep_me
              then ((VarSet -> Id -> VarSet
extendVarSet VarSet
set Id
v, Id
vId -> [Id] -> [Id]
forall a. a -> [a] -> [a]
:[Id]
ids), ())
              else ((VarSet
set,                [Id]
ids),   ())


dffvExpr :: CoreExpr -> DFFV ()
dffvExpr :: Expr Id -> DFFV ()
dffvExpr (Var Id
v)              = Id -> DFFV ()
insert Id
v
dffvExpr (App Expr Id
e1 Expr Id
e2)          = Expr Id -> DFFV ()
dffvExpr Expr Id
e1 DFFV () -> DFFV () -> DFFV ()
forall a b. DFFV a -> DFFV b -> DFFV b
forall (m :: * -> *) a b. Monad m => m a -> m b -> m b
>> Expr Id -> DFFV ()
dffvExpr Expr Id
e2
dffvExpr (Lam Id
v Expr Id
e)            = Id -> DFFV () -> DFFV ()
forall a. Id -> DFFV a -> DFFV a
extendScope Id
v (Expr Id -> DFFV ()
dffvExpr Expr Id
e)
dffvExpr (Tick (Breakpoint XBreakpoint 'TickishPassCore
_ Arity
_ [XTickishId 'TickishPassCore]
ids Module
_) Expr Id
e) = (Id -> DFFV ()) -> [Id] -> DFFV ()
forall (t :: * -> *) (m :: * -> *) a b.
(Foldable t, Monad m) =>
(a -> m b) -> t a -> m ()
mapM_ Id -> DFFV ()
insert [Id]
[XTickishId 'TickishPassCore]
ids DFFV () -> DFFV () -> DFFV ()
forall a b. DFFV a -> DFFV b -> DFFV b
forall (m :: * -> *) a b. Monad m => m a -> m b -> m b
>> Expr Id -> DFFV ()
dffvExpr Expr Id
e
dffvExpr (Tick GenTickish 'TickishPassCore
_other Expr Id
e)    = Expr Id -> DFFV ()
dffvExpr Expr Id
e
dffvExpr (Cast Expr Id
e CoercionR
_)           = Expr Id -> DFFV ()
dffvExpr Expr Id
e
dffvExpr (Let (NonRec Id
x Expr Id
r) Expr Id
e) = (Id, Expr Id) -> DFFV ()
dffvBind (Id
x,Expr Id
r) DFFV () -> DFFV () -> DFFV ()
forall a b. DFFV a -> DFFV b -> DFFV b
forall (m :: * -> *) a b. Monad m => m a -> m b -> m b
>> Id -> DFFV () -> DFFV ()
forall a. Id -> DFFV a -> DFFV a
extendScope Id
x (Expr Id -> DFFV ()
dffvExpr Expr Id
e)
dffvExpr (Let (Rec [(Id, Expr Id)]
prs) Expr Id
e)    = [Id] -> DFFV () -> DFFV ()
forall a. [Id] -> DFFV a -> DFFV a
extendScopeList (((Id, Expr Id) -> Id) -> [(Id, Expr Id)] -> [Id]
forall a b. (a -> b) -> [a] -> [b]
map (Id, Expr Id) -> Id
forall a b. (a, b) -> a
fst [(Id, Expr Id)]
prs) (DFFV () -> DFFV ()) -> DFFV () -> DFFV ()
forall a b. (a -> b) -> a -> b
$
                                (((Id, Expr Id) -> DFFV ()) -> [(Id, Expr Id)] -> DFFV ()
forall (t :: * -> *) (m :: * -> *) a b.
(Foldable t, Monad m) =>
(a -> m b) -> t a -> m ()
mapM_ (Id, Expr Id) -> DFFV ()
dffvBind [(Id, Expr Id)]
prs DFFV () -> DFFV () -> DFFV ()
forall a b. DFFV a -> DFFV b -> DFFV b
forall (m :: * -> *) a b. Monad m => m a -> m b -> m b
>> Expr Id -> DFFV ()
dffvExpr Expr Id
e)
dffvExpr (Case Expr Id
e Id
b Type
_ [Alt Id]
as)      = Expr Id -> DFFV ()
dffvExpr Expr Id
e DFFV () -> DFFV () -> DFFV ()
forall a b. DFFV a -> DFFV b -> DFFV b
forall (m :: * -> *) a b. Monad m => m a -> m b -> m b
>> Id -> DFFV () -> DFFV ()
forall a. Id -> DFFV a -> DFFV a
extendScope Id
b ((Alt Id -> DFFV ()) -> [Alt Id] -> DFFV ()
forall (t :: * -> *) (m :: * -> *) a b.
(Foldable t, Monad m) =>
(a -> m b) -> t a -> m ()
mapM_ Alt Id -> DFFV ()
dffvAlt [Alt Id]
as)
dffvExpr Expr Id
_other               = () -> DFFV ()
forall a. a -> DFFV a
forall (m :: * -> *) a. Monad m => a -> m a
return ()

dffvAlt :: CoreAlt -> DFFV ()
dffvAlt :: Alt Id -> DFFV ()
dffvAlt (Alt AltCon
_ [Id]
xs Expr Id
r) = [Id] -> DFFV () -> DFFV ()
forall a. [Id] -> DFFV a -> DFFV a
extendScopeList [Id]
xs (Expr Id -> DFFV ()
dffvExpr Expr Id
r)

dffvBind :: (Id, CoreExpr) -> DFFV ()
dffvBind :: (Id, Expr Id) -> DFFV ()
dffvBind(Id
x,Expr Id
r)
  | Bool -> Bool
not (Id -> Bool
isId Id
x) = Expr Id -> DFFV ()
dffvExpr Expr Id
r
  | Bool
otherwise    = Bool -> Id -> DFFV ()
dffvLetBndr Bool
False Id
x DFFV () -> DFFV () -> DFFV ()
forall a b. DFFV a -> DFFV b -> DFFV b
forall (m :: * -> *) a b. Monad m => m a -> m b -> m b
>> Expr Id -> DFFV ()
dffvExpr Expr Id
r
                -- Pass False because we are doing the RHS right here
                -- If you say True you'll get *exponential* behaviour!

dffvLetBndr :: Bool -> Id -> DFFV ()
-- Gather the free vars of the RULES and unfolding of a binder
-- We always get the free vars of a *stable* unfolding, but
-- for a *vanilla* one (VanillaSrc), the flag controls what happens:
--   True <=> get fvs of even a *vanilla* unfolding
--   False <=> ignore a VanillaSrc
-- For nested bindings (call from dffvBind) we always say "False" because
--       we are taking the fvs of the RHS anyway
-- For top-level bindings (call from addExternal, via bndrFvsInOrder)
--       we say "True" if we are exposing that unfolding
dffvLetBndr :: Bool -> Id -> DFFV ()
dffvLetBndr Bool
vanilla_unfold Id
id
  = do { Unfolding -> DFFV ()
go_unf (IdInfo -> Unfolding
realUnfoldingInfo IdInfo
idinfo)
       ; (CoreRule -> DFFV ()) -> [CoreRule] -> DFFV ()
forall (t :: * -> *) (m :: * -> *) a b.
(Foldable t, Monad m) =>
(a -> m b) -> t a -> m ()
mapM_ CoreRule -> DFFV ()
go_rule (RuleInfo -> [CoreRule]
ruleInfoRules (IdInfo -> RuleInfo
ruleInfo IdInfo
idinfo)) }
  where
    idinfo :: IdInfo
idinfo = HasDebugCallStack => Id -> IdInfo
Id -> IdInfo
idInfo Id
id

    go_unf :: Unfolding -> DFFV ()
go_unf (CoreUnfolding { uf_tmpl :: Unfolding -> Expr Id
uf_tmpl = Expr Id
rhs, uf_src :: Unfolding -> UnfoldingSource
uf_src = UnfoldingSource
src })
       | UnfoldingSource -> Bool
isStableSource UnfoldingSource
src = Expr Id -> DFFV ()
dffvExpr Expr Id
rhs
       | Bool
vanilla_unfold     = Expr Id -> DFFV ()
dffvExpr Expr Id
rhs
       | Bool
otherwise          = () -> DFFV ()
forall a. a -> DFFV a
forall (m :: * -> *) a. Monad m => a -> m a
return ()

    go_unf (DFunUnfolding { df_bndrs :: Unfolding -> [Id]
df_bndrs = [Id]
bndrs, df_args :: Unfolding -> [Expr Id]
df_args = [Expr Id]
args })
             = [Id] -> DFFV () -> DFFV ()
forall a. [Id] -> DFFV a -> DFFV a
extendScopeList [Id]
bndrs (DFFV () -> DFFV ()) -> DFFV () -> DFFV ()
forall a b. (a -> b) -> a -> b
$ (Expr Id -> DFFV ()) -> [Expr Id] -> DFFV ()
forall (t :: * -> *) (m :: * -> *) a b.
(Foldable t, Monad m) =>
(a -> m b) -> t a -> m ()
mapM_ Expr Id -> DFFV ()
dffvExpr [Expr Id]
args
    go_unf Unfolding
_ = () -> DFFV ()
forall a. a -> DFFV a
forall (m :: * -> *) a. Monad m => a -> m a
return ()

    go_rule :: CoreRule -> DFFV ()
go_rule (BuiltinRule {}) = () -> DFFV ()
forall a. a -> DFFV a
forall (m :: * -> *) a. Monad m => a -> m a
return ()
    go_rule (Rule { ru_bndrs :: CoreRule -> [Id]
ru_bndrs = [Id]
bndrs, ru_rhs :: CoreRule -> Expr Id
ru_rhs = Expr Id
rhs })
      = [Id] -> DFFV () -> DFFV ()
forall a. [Id] -> DFFV a -> DFFV a
extendScopeList [Id]
bndrs (Expr Id -> DFFV ()
dffvExpr Expr Id
rhs)

{-
************************************************************************
*                                                                      *
               findExternalRules
*                                                                      *
************************************************************************

Note [Finding external rules]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The complete rules are gotten by combining
   a) local rules for imported Ids
   b) rules embedded in the top-level Ids

There are two complications:
  * Note [Which rules to expose]
  * Note [Trimming auto-rules]

Note [Which rules to expose]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The function 'expose_rule' filters out rules that mention, on the LHS,
Ids that aren't externally visible; these rules can't fire in a client
module.

The externally-visible binders are computed (by chooseExternalIds)
assuming that all orphan rules are externalised (see init_ext_ids in
function 'search'). So in fact it's a bit conservative and we may
export more than we need.  (It's a sort of mutual recursion.)

Note [Trimming auto-rules]
~~~~~~~~~~~~~~~~~~~~~~~~~~~
Second, with auto-specialisation we may specialise local or imported
dfuns or INLINE functions, and then later inline them.  That may leave
behind something like
   RULE "foo" forall d. f @ Int d = f_spec
where f is either local or imported, and there is no remaining
reference to f_spec except from the RULE.

Now that RULE *might* be useful to an importing module, but that is
purely speculative, and meanwhile the code is taking up space and
codegen time.  I found that binary sizes jumped by 6-10% when I
started to specialise INLINE functions (again, Note [Inline
specialisations] in GHC.Core.Opt.Specialise).

So it seems better to drop the binding for f_spec, and the rule
itself, if the auto-generated rule is the *only* reason that it is
being kept alive.

(The RULE still might have been useful in the past; that is, it was
the right thing to have generated it in the first place.  See Note
[Inline specialisations] in GHC.Core.Opt.Specialise. But now it has
served its purpose, and can be discarded.)

So findExternalRules does this:
  * Remove all bindings that are kept alive *only* by isAutoRule rules
      (this is done in trim_binds)
  * Remove all auto rules that mention bindings that have been removed
      (this is done by filtering by keep_rule)

NB: if a binding is kept alive for some *other* reason (e.g. f_spec is
called in the final code), we keep the rule too.

This stuff is the only reason for the ru_auto field in a Rule.

We discard auto-rules by default, but keep them if -fkeep-auto-rules is on.

* Discard by default: in #18532 we looked at keeping auto-rules and it turned out to just make
  compiler performance worse while increasing code sizes at the same time. The
  impact varied. Compiling Cabal got ~3% slower, allocated ~3% more and wrote 15%
  more code to disk.  Nofib only saw 0.7% more compiler allocations and executable
  file size growth. But given there was no difference in runtime for these
  benchmarks it turned out to be flat out worse.  See the ticket for more details.

* Keep with -fkeep-auto-rules: in #21917 we found cases where we get a lot code
  duplication when we discard specialisations.  Agda is a case in point.  Having
  a flag gives us control over the rule-trimming decision.
-}

findExternalRules :: TidyOpts
                  -> [CoreBind]
                  -> [CoreRule] -- Local rules for imported fns
                  -> UnfoldEnv  -- Ids that are exported, so we need their rules
                  -> ([CoreBind], [CoreRule])
-- See Note [Finding external rules]
findExternalRules :: TidyOpts
-> CoreProgram
-> [CoreRule]
-> UnfoldEnv
-> (CoreProgram, [CoreRule])
findExternalRules TidyOpts
opts CoreProgram
binds [CoreRule]
imp_id_rules UnfoldEnv
unfold_env
  = (CoreProgram
trimmed_binds, (CoreRule -> Bool) -> [CoreRule] -> [CoreRule]
forall a. (a -> Bool) -> [a] -> [a]
filter CoreRule -> Bool
keep_rule [CoreRule]
all_rules)
  where
    imp_rules :: [CoreRule]
imp_rules | TidyOpts -> Bool
opt_expose_rules TidyOpts
opts = (CoreRule -> Bool) -> [CoreRule] -> [CoreRule]
forall a. (a -> Bool) -> [a] -> [a]
filter CoreRule -> Bool
expose_rule [CoreRule]
imp_id_rules
              | Bool
otherwise             = []
    imp_user_rule_fvs :: VarSet
imp_user_rule_fvs = (CoreRule -> VarSet) -> [CoreRule] -> VarSet
forall a. (a -> VarSet) -> [a] -> VarSet
mapUnionVarSet CoreRule -> VarSet
user_rule_rhs_fvs [CoreRule]
imp_rules

    user_rule_rhs_fvs :: CoreRule -> VarSet
user_rule_rhs_fvs CoreRule
rule | CoreRule -> Bool
isAutoRule CoreRule
rule Bool -> Bool -> Bool
&& Bool -> Bool
not (TidyOpts -> Bool
opt_keep_auto_rules TidyOpts
opts)
                                             = VarSet
emptyVarSet
                           | Bool
otherwise       = CoreRule -> VarSet
ruleRhsFreeVars CoreRule
rule

    (CoreProgram
trimmed_binds, VarSet
local_bndrs, VarSet
_, [CoreRule]
all_rules) = CoreProgram -> (CoreProgram, VarSet, VarSet, [CoreRule])
trim_binds CoreProgram
binds

    keep_rule :: CoreRule -> Bool
keep_rule CoreRule
rule = CoreRule -> VarSet
ruleFreeVars CoreRule
rule VarSet -> VarSet -> Bool
`subVarSet` VarSet
local_bndrs
        -- Remove rules that make no sense, because they mention a
        -- local binder (on LHS or RHS) that we have now discarded.
        -- (NB: ruleFreeVars only includes LocalIds)
        --
        -- LHS: we have already filtered out rules that mention internal Ids
        --     on LHS but that isn't enough because we might have by now
        --     discarded a binding with an external Id. (How?
        --     chooseExternalIds is a bit conservative.)
        --
        -- RHS: the auto rules that might mention a binder that has
        --      been discarded; see Note [Trimming auto-rules]

    expose_rule :: CoreRule -> Bool
expose_rule CoreRule
rule = (Id -> Bool) -> [Id] -> Bool
forall (t :: * -> *) a. Foldable t => (a -> Bool) -> t a -> Bool
all Id -> Bool
is_external_id (CoreRule -> [Id]
ruleLhsFreeIdsList CoreRule
rule)
                -- Don't expose a rule whose LHS mentions a locally-defined
                -- Id that is completely internal (i.e. not visible to an
                -- importing module).  NB: ruleLhsFreeIds only returns LocalIds.
                -- See Note [Which rules to expose]

    is_external_id :: Id -> Bool
is_external_id Id
id = case UnfoldEnv -> Id -> Maybe (Name, Bool)
forall a. VarEnv a -> Id -> Maybe a
lookupVarEnv UnfoldEnv
unfold_env Id
id of
                          Just (Name
name, Bool
_) -> Name -> Bool
isExternalName Name
name Bool -> Bool -> Bool
&& Bool -> Bool
not (Id -> Bool
isImplicitId Id
id)
                          Maybe (Name, Bool)
Nothing        -> Bool
False

    trim_binds :: [CoreBind]
               -> ( [CoreBind]   -- Trimmed bindings
                  , VarSet       -- Binders of those bindings
                  , VarSet       -- Free vars of those bindings + rhs of user rules
                                 -- (we don't bother to delete the binders)
                  , [CoreRule])  -- All rules, imported + from the bindings
    -- This function removes unnecessary bindings, and gathers up rules from
    -- the bindings we keep.  See Note [Trimming auto-rules]
    trim_binds :: CoreProgram -> (CoreProgram, VarSet, VarSet, [CoreRule])
trim_binds []  -- Base case, start with imp_user_rule_fvs
       = ([], VarSet
emptyVarSet, VarSet
imp_user_rule_fvs, [CoreRule]
imp_rules)

    trim_binds (CoreBind
bind:CoreProgram
binds)
       | (Id -> Bool) -> [Id] -> Bool
forall (t :: * -> *) a. Foldable t => (a -> Bool) -> t a -> Bool
any Id -> Bool
needed [Id]
bndrs    -- Keep this binding
       = ( CoreBind
bind CoreBind -> CoreProgram -> CoreProgram
forall a. a -> [a] -> [a]
: CoreProgram
binds', VarSet
bndr_set', VarSet
needed_fvs', [CoreRule]
local_rules [CoreRule] -> [CoreRule] -> [CoreRule]
forall a. [a] -> [a] -> [a]
++ [CoreRule]
rules )
       | Bool
otherwise           -- Discard binding altogether
       = (CoreProgram, VarSet, VarSet, [CoreRule])
stuff
       where
         stuff :: (CoreProgram, VarSet, VarSet, [CoreRule])
stuff@(CoreProgram
binds', VarSet
bndr_set, VarSet
needed_fvs, [CoreRule]
rules)
                       = CoreProgram -> (CoreProgram, VarSet, VarSet, [CoreRule])
trim_binds CoreProgram
binds
         needed :: Id -> Bool
needed Id
bndr   = Id -> Bool
isExportedId Id
bndr Bool -> Bool -> Bool
|| Id
bndr Id -> VarSet -> Bool
`elemVarSet` VarSet
needed_fvs

         bndrs :: [Id]
bndrs         = CoreBind -> [Id]
forall b. Bind b -> [b]
bindersOf  CoreBind
bind
         rhss :: [Expr Id]
rhss          = CoreBind -> [Expr Id]
forall b. Bind b -> [Expr b]
rhssOfBind CoreBind
bind
         bndr_set' :: VarSet
bndr_set'     = VarSet
bndr_set VarSet -> [Id] -> VarSet
`extendVarSetList` [Id]
bndrs

         needed_fvs' :: VarSet
needed_fvs'   = VarSet
needed_fvs                                   VarSet -> VarSet -> VarSet
`unionVarSet`
                         (Id -> VarSet) -> [Id] -> VarSet
forall a. (a -> VarSet) -> [a] -> VarSet
mapUnionVarSet Id -> VarSet
idUnfoldingVars   [Id]
bndrs       VarSet -> VarSet -> VarSet
`unionVarSet`
                              -- Ignore type variables in the type of bndrs
                         (Expr Id -> VarSet) -> [Expr Id] -> VarSet
forall a. (a -> VarSet) -> [a] -> VarSet
mapUnionVarSet Expr Id -> VarSet
exprFreeVars      [Expr Id]
rhss        VarSet -> VarSet -> VarSet
`unionVarSet`
                         (CoreRule -> VarSet) -> [CoreRule] -> VarSet
forall a. (a -> VarSet) -> [a] -> VarSet
mapUnionVarSet CoreRule -> VarSet
user_rule_rhs_fvs [CoreRule]
local_rules
            -- In needed_fvs', we don't bother to delete binders from the fv set

         local_rules :: [CoreRule]
local_rules  = [ CoreRule
rule
                        | TidyOpts -> Bool
opt_expose_rules TidyOpts
opts
                        , Id
id <- [Id]
bndrs
                        , Id -> Bool
is_external_id Id
id   -- Only collect rules for external Ids
                        , CoreRule
rule <- Id -> [CoreRule]
idCoreRules Id
id
                        , CoreRule -> Bool
expose_rule CoreRule
rule ]  -- and ones that can fire in a client

{-
************************************************************************
*                                                                      *
               tidyTopName
*                                                                      *
************************************************************************

This is where we set names to local/global based on whether they really are
externally visible (see comment at the top of this module).  If the name
was previously local, we have to give it a unique occurrence name if
we intend to externalise it.
-}

tidyTopName :: Module -> NameCache -> Maybe Id -> TidyOccEnv
            -> Id -> IO (TidyOccEnv, Name)
tidyTopName :: Module
-> NameCache
-> Maybe Id
-> TidyOccEnv
-> Id
-> IO (TidyOccEnv, Name)
tidyTopName Module
mod NameCache
name_cache Maybe Id
maybe_ref TidyOccEnv
occ_env Id
id
  | Bool
global Bool -> Bool -> Bool
&& Bool
internal = (TidyOccEnv, Name) -> IO (TidyOccEnv, Name)
forall a. a -> IO a
forall (m :: * -> *) a. Monad m => a -> m a
return (TidyOccEnv
occ_env, Name -> Name
localiseName Name
name)

  | Bool
global Bool -> Bool -> Bool
&& Bool
external = (TidyOccEnv, Name) -> IO (TidyOccEnv, Name)
forall a. a -> IO a
forall (m :: * -> *) a. Monad m => a -> m a
return (TidyOccEnv
occ_env, Name
name)
        -- Global names are assumed to have been allocated by the renamer,
        -- so they already have the "right" unique
        -- And it's a system-wide unique too

  -- Now we get to the real reason that all this is in the IO Monad:
  -- we have to update the name cache in a nice atomic fashion

  | Bool
local  Bool -> Bool -> Bool
&& Bool
internal = do uniq <- NameCache -> IO Unique
takeUniqFromNameCache NameCache
name_cache
                            -- See #19619
                            let new_local_name = OccName
occ' OccName -> Name -> Name
forall a b. a -> b -> b
`seq` Unique -> OccName -> SrcSpan -> Name
mkInternalName Unique
uniq OccName
occ' SrcSpan
loc
                            return (occ_env', new_local_name)
        -- Even local, internal names must get a unique occurrence.
        -- This is necessary because the byte-code generator the byte-code
        -- generator builds a system-wide Name->BCO symbol table.

  | Bool
local  Bool -> Bool -> Bool
&& Bool
external = do new_external_name <- NameCache -> Module -> OccName -> SrcSpan -> IO Name
allocateGlobalBinder NameCache
name_cache Module
mod OccName
occ' SrcSpan
loc
                            return (occ_env', new_external_name)
        -- If we want to externalise a currently-local name, check
        -- whether we have already assigned a unique for it.
        -- If so, use it; if not, extend the table.
        -- All this is done by allocateGlobalBinder.
        -- This is needed when *re*-compiling a module in GHCi; we must
        -- use the same name for externally-visible things as we did before.

  | Bool
otherwise = String -> IO (TidyOccEnv, Name)
forall a. HasCallStack => String -> a
panic String
"tidyTopName"
  where
    !name :: Name
name       = Id -> Name
idName Id
id
    external :: Bool
external    = Maybe Id -> Bool
forall a. Maybe a -> Bool
isJust Maybe Id
maybe_ref
    global :: Bool
global      = Name -> Bool
isExternalName Name
name
    local :: Bool
local       = Bool -> Bool
not Bool
global
    internal :: Bool
internal    = Bool -> Bool
not Bool
external
    !loc :: SrcSpan
loc        = Name -> SrcSpan
nameSrcSpan Name
name

    old_occ :: OccName
old_occ     = Name -> OccName
nameOccName Name
name
    new_occ :: OccName
new_occ | Just Id
ref <- Maybe Id
maybe_ref
            , Id
ref Id -> Id -> Bool
forall a. Eq a => a -> a -> Bool
/= Id
id
            = NameSpace -> String -> OccName
mkOccName (OccName -> NameSpace
occNameSpace OccName
old_occ) (String -> OccName) -> String -> OccName
forall a b. (a -> b) -> a -> b
$
                   let
                       ref_str :: String
ref_str = OccName -> String
occNameString (Id -> OccName
forall a. NamedThing a => a -> OccName
getOccName Id
ref)
                       occ_str :: String
occ_str = OccName -> String
occNameString OccName
old_occ
                   in
                   case String
occ_str of
                     Char
'$':Char
'w':String
_ -> String
occ_str
                        -- workers: the worker for a function already
                        -- includes the occname for its parent, so there's
                        -- no need to prepend the referrer.
                     String
_other | Name -> Bool
isSystemName Name
name -> String
ref_str
                            | Bool
otherwise         -> String
ref_str String -> ShowS
forall a. [a] -> [a] -> [a]
++ Char
'_' Char -> ShowS
forall a. a -> [a] -> [a]
: String
occ_str
                        -- If this name was system-generated, then don't bother
                        -- to retain its OccName, just use the referrer.  These
                        -- system-generated names will become "f1", "f2", etc. for
                        -- a referrer "f".
            | Bool
otherwise = OccName
old_occ

    (TidyOccEnv
occ_env', OccName
occ') = TidyOccEnv -> OccName -> (TidyOccEnv, OccName)
tidyOccName TidyOccEnv
occ_env OccName
new_occ


{-
************************************************************************
*                                                                      *
\subsection{Step 2: top-level tidying}
*                                                                      *
************************************************************************
-}

-- TopTidyEnv: when tidying we need to know
--   * name_cache: The NameCache, containing a unique supply and any pre-ordained Names.
--        These may have arisen because the
--        renamer read in an interface file mentioning M.$wf, say,
--        and assigned it unique r77.  If, on this compilation, we've
--        invented an Id whose name is $wf (but with a different unique)
--        we want to rename it to have unique r77, so that we can do easy
--        comparisons with stuff from the interface file
--
--   * occ_env: The TidyOccEnv, which tells us which local occurrences
--     are 'used'
--
--   * subst_env: A Var->Var mapping that substitutes the new Var for the old

tidyTopBinds :: UnfoldEnv
             -> NameSet
             -> TidyOccEnv
             -> CoreProgram
             -> IO (TidyEnv, CoreProgram)

tidyTopBinds :: UnfoldEnv
-> NameSet
-> TidyOccEnv
-> CoreProgram
-> IO (TidyEnv, CoreProgram)
tidyTopBinds UnfoldEnv
unfold_env NameSet
boot_exports TidyOccEnv
init_occ_env CoreProgram
binds
  = do let result :: (TidyEnv, CoreProgram)
result = TidyEnv -> CoreProgram -> (TidyEnv, CoreProgram)
tidy TidyEnv
init_env CoreProgram
binds
       CoreProgram -> ()
seqBinds ((TidyEnv, CoreProgram) -> CoreProgram
forall a b. (a, b) -> b
snd (TidyEnv, CoreProgram)
result) () -> IO (TidyEnv, CoreProgram) -> IO (TidyEnv, CoreProgram)
forall a b. a -> b -> b
`seq` (TidyEnv, CoreProgram) -> IO (TidyEnv, CoreProgram)
forall a. a -> IO a
forall (m :: * -> *) a. Monad m => a -> m a
return (TidyEnv, CoreProgram)
result
       -- This seqBinds avoids a spike in space usage (see #13564)
  where
    init_env :: TidyEnv
init_env = (TidyOccEnv
init_occ_env, VarEnv Id
forall a. VarEnv a
emptyVarEnv)

    tidy :: TidyEnv -> CoreProgram -> (TidyEnv, CoreProgram)
tidy = (TidyEnv -> CoreBind -> (TidyEnv, CoreBind))
-> TidyEnv -> CoreProgram -> (TidyEnv, CoreProgram)
forall (t :: * -> *) s a b.
Traversable t =>
(s -> a -> (s, b)) -> s -> t a -> (s, t b)
mapAccumL (UnfoldEnv -> NameSet -> TidyEnv -> CoreBind -> (TidyEnv, CoreBind)
tidyTopBind UnfoldEnv
unfold_env NameSet
boot_exports)

------------------------
tidyTopBind  :: UnfoldEnv
             -> NameSet
             -> TidyEnv
             -> CoreBind
             -> (TidyEnv, CoreBind)

tidyTopBind :: UnfoldEnv -> NameSet -> TidyEnv -> CoreBind -> (TidyEnv, CoreBind)
tidyTopBind UnfoldEnv
unfold_env NameSet
boot_exports
            (TidyOccEnv
occ_env,VarEnv Id
subst1) (NonRec Id
bndr Expr Id
rhs)
  = (TidyEnv
tidy_env2,  Id -> Expr Id -> CoreBind
forall b. b -> Expr b -> Bind b
NonRec Id
bndr' Expr Id
rhs')
  where
    (Id
bndr', Expr Id
rhs') = UnfoldEnv -> NameSet -> TidyEnv -> (Id, Expr Id) -> (Id, Expr Id)
tidyTopPair UnfoldEnv
unfold_env NameSet
boot_exports TidyEnv
tidy_env2 (Id
bndr, Expr Id
rhs)
    subst2 :: VarEnv Id
subst2        = VarEnv Id -> Id -> Id -> VarEnv Id
forall a. VarEnv a -> Id -> a -> VarEnv a
extendVarEnv VarEnv Id
subst1 Id
bndr Id
bndr'
    tidy_env2 :: TidyEnv
tidy_env2     = (TidyOccEnv
occ_env, VarEnv Id
subst2)

tidyTopBind UnfoldEnv
unfold_env NameSet
boot_exports (TidyOccEnv
occ_env, VarEnv Id
subst1) (Rec [(Id, Expr Id)]
prs)
  = (TidyEnv
tidy_env2, [(Id, Expr Id)] -> CoreBind
forall b. [(b, Expr b)] -> Bind b
Rec [(Id, Expr Id)]
prs')
  where
    prs' :: [(Id, Expr Id)]
prs'      = ((Id, Expr Id) -> (Id, Expr Id))
-> [(Id, Expr Id)] -> [(Id, Expr Id)]
forall a b. (a -> b) -> [a] -> [b]
map (UnfoldEnv -> NameSet -> TidyEnv -> (Id, Expr Id) -> (Id, Expr Id)
tidyTopPair UnfoldEnv
unfold_env NameSet
boot_exports TidyEnv
tidy_env2) [(Id, Expr Id)]
prs
    subst2 :: VarEnv Id
subst2    = VarEnv Id -> [(Id, Id)] -> VarEnv Id
forall a. VarEnv a -> [(Id, a)] -> VarEnv a
extendVarEnvList VarEnv Id
subst1 (((Id, Expr Id) -> Id) -> [(Id, Expr Id)] -> [Id]
forall a b. (a -> b) -> [a] -> [b]
map (Id, Expr Id) -> Id
forall a b. (a, b) -> a
fst [(Id, Expr Id)]
prs [Id] -> [Id] -> [(Id, Id)]
forall a b. [a] -> [b] -> [(a, b)]
`zip` ((Id, Expr Id) -> Id) -> [(Id, Expr Id)] -> [Id]
forall a b. (a -> b) -> [a] -> [b]
map (Id, Expr Id) -> Id
forall a b. (a, b) -> a
fst [(Id, Expr Id)]
prs')
    tidy_env2 :: TidyEnv
tidy_env2 = (TidyOccEnv
occ_env, VarEnv Id
subst2)
    -- This is where we "tie the knot": tidy_env2 is fed into tidyTopPair

-----------------------------------------------------------
tidyTopPair :: UnfoldEnv
            -> NameSet
            -> TidyEnv  -- The TidyEnv is used to tidy the IdInfo
                        -- It is knot-tied: don't look at it!
            -> (Id, CoreExpr)   -- Binder and RHS before tidying
            -> (Id, CoreExpr)
        -- This function is the heart of Step 2
        -- The rec_tidy_env is the one to use for the IdInfo
        -- It's necessary because when we are dealing with a recursive
        -- group, a variable late in the group might be mentioned
        -- in the IdInfo of one early in the group

tidyTopPair :: UnfoldEnv -> NameSet -> TidyEnv -> (Id, Expr Id) -> (Id, Expr Id)
tidyTopPair UnfoldEnv
unfold_env NameSet
boot_exports TidyEnv
rhs_tidy_env (Id
bndr, Expr Id
rhs)
  = -- pprTrace "tidyTop" (ppr name' <+> ppr details <+> ppr rhs) $
    (Id
bndr1, Expr Id
rhs1)

  where
    Just (Name
name',Bool
show_unfold) = UnfoldEnv -> Id -> Maybe (Name, Bool)
forall a. VarEnv a -> Id -> Maybe a
lookupVarEnv UnfoldEnv
unfold_env Id
bndr
    !cbv_bndr :: Id
cbv_bndr = HasDebugCallStack => NameSet -> Id -> Expr Id -> Id
NameSet -> Id -> Expr Id -> Id
tidyCbvInfoTop NameSet
boot_exports Id
bndr Expr Id
rhs
    bndr1 :: Id
bndr1    = IdDetails -> Name -> Type -> IdInfo -> Id
mkGlobalId IdDetails
details Name
name' Type
ty' IdInfo
idinfo'
    details :: IdDetails
details  = Id -> IdDetails
idDetails Id
cbv_bndr -- Preserve the IdDetails
    ty' :: Type
ty'      = Type -> Type
tidyTopType (Id -> Type
idType Id
cbv_bndr)
    rhs1 :: Expr Id
rhs1     = TidyEnv -> Expr Id -> Expr Id
tidyExpr TidyEnv
rhs_tidy_env Expr Id
rhs
    idinfo' :: IdInfo
idinfo'  = TidyEnv
-> Name -> Type -> Expr Id -> Expr Id -> IdInfo -> Bool -> IdInfo
tidyTopIdInfo TidyEnv
rhs_tidy_env Name
name' Type
ty'
                             Expr Id
rhs Expr Id
rhs1 (HasDebugCallStack => Id -> IdInfo
Id -> IdInfo
idInfo Id
cbv_bndr) Bool
show_unfold

-- tidyTopIdInfo creates the final IdInfo for top-level
-- binders.  The delicate piece:
--
--  * Arity.  After CoreTidy, this arity must not change any more.
--      Indeed, CorePrep must eta expand where necessary to make
--      the manifest arity equal to the claimed arity.
--
tidyTopIdInfo :: TidyEnv -> Name -> Type
              -> CoreExpr -> CoreExpr -> IdInfo -> Bool -> IdInfo
tidyTopIdInfo :: TidyEnv
-> Name -> Type -> Expr Id -> Expr Id -> IdInfo -> Bool -> IdInfo
tidyTopIdInfo TidyEnv
rhs_tidy_env Name
name Type
rhs_ty Expr Id
orig_rhs Expr Id
tidy_rhs IdInfo
idinfo Bool
show_unfold
  | Bool -> Bool
not Bool
is_external     -- For internal Ids (not externally visible)
  = IdInfo
vanillaIdInfo       -- we only need enough info for code generation
                        -- Arity and strictness info are enough;
                        --      c.f. GHC.Core.Tidy.tidyLetBndr
        IdInfo -> Arity -> IdInfo
`setArityInfo`      Arity
arity
        IdInfo -> DmdSig -> IdInfo
`setDmdSigInfo`     DmdSig
final_sig
        IdInfo -> CprSig -> IdInfo
`setCprSigInfo`     CprSig
final_cpr
        IdInfo -> Unfolding -> IdInfo
`setUnfoldingInfo`  Unfolding
minimal_unfold_info  -- See note [Preserve evaluatedness]
                                                 -- in GHC.Core.Tidy

  | Bool
otherwise           -- Externally-visible Ids get the whole lot
  = IdInfo
vanillaIdInfo
        IdInfo -> Arity -> IdInfo
`setArityInfo`       Arity
arity
        IdInfo -> DmdSig -> IdInfo
`setDmdSigInfo`      DmdSig
final_sig
        IdInfo -> CprSig -> IdInfo
`setCprSigInfo`      CprSig
final_cpr
        IdInfo -> OccInfo -> IdInfo
`setOccInfo`         OccInfo
robust_occ_info
        IdInfo -> InlinePragma -> IdInfo
`setInlinePragInfo`  IdInfo -> InlinePragma
inlinePragInfo IdInfo
idinfo
        IdInfo -> Unfolding -> IdInfo
`setUnfoldingInfo`   Unfolding
unfold_info
                -- NB: we throw away the Rules
                -- They have already been extracted by findExternalRules
  where
    is_external :: Bool
is_external = Name -> Bool
isExternalName Name
name

    --------- OccInfo ------------
    robust_occ_info :: OccInfo
robust_occ_info = OccInfo -> OccInfo
zapFragileOcc (IdInfo -> OccInfo
occInfo IdInfo
idinfo)
    -- It's important to keep loop-breaker information
    -- when we are doing -fexpose-all-unfoldings

    --------- Strictness ------------
    mb_bot_str :: Maybe (Arity, DmdSig, CprSig)
mb_bot_str = Expr Id -> Maybe (Arity, DmdSig, CprSig)
exprBotStrictness_maybe Expr Id
orig_rhs

    sig :: DmdSig
sig = IdInfo -> DmdSig
dmdSigInfo IdInfo
idinfo
    final_sig :: DmdSig
final_sig | Bool -> Bool
not (DmdSig -> Bool
isNopSig DmdSig
sig)
              = Bool -> String -> SDoc -> DmdSig -> DmdSig
forall a. HasCallStack => Bool -> String -> SDoc -> a -> a
warnPprTrace (DmdSig -> Bool
_bottom_hidden DmdSig
sig) String
"tidyTopIdInfo" (Name -> SDoc
forall a. Outputable a => a -> SDoc
ppr Name
name) DmdSig
sig

              -- No demand signature, so try a
              -- cheap-and-cheerful bottom analyser
              | Just (Arity
_, DmdSig
bot_str_sig, CprSig
_) <- Maybe (Arity, DmdSig, CprSig)
mb_bot_str
              = DmdSig
bot_str_sig

              -- No strictness info
              | Bool
otherwise = DmdSig
nopSig

    cpr :: CprSig
cpr = IdInfo -> CprSig
cprSigInfo IdInfo
idinfo
    final_cpr :: CprSig
final_cpr | Just (Arity
_, DmdSig
_, CprSig
bot_cpr_sig) <- Maybe (Arity, DmdSig, CprSig)
mb_bot_str
              = CprSig
bot_cpr_sig
              | Bool
otherwise
              = CprSig
cpr

    _bottom_hidden :: DmdSig -> Bool
_bottom_hidden DmdSig
id_sig
      = case Maybe (Arity, DmdSig, CprSig)
mb_bot_str of
          Maybe (Arity, DmdSig, CprSig)
Nothing            -> Bool
False
          Just (Arity
arity, DmdSig
_, CprSig
_) -> Bool -> Bool
not (DmdSig -> Arity -> Bool
isDeadEndAppSig DmdSig
id_sig Arity
arity)

    --------- Unfolding ------------
    -- Force unfold_info (hence bangs), otherwise the old unfolding
    -- is retained during code generation. See #22071

    unf_info :: Unfolding
unf_info = IdInfo -> Unfolding
realUnfoldingInfo IdInfo
idinfo
    !minimal_unfold_info :: Unfolding
minimal_unfold_info = Unfolding -> Unfolding
trimUnfolding Unfolding
unf_info

    !unfold_info :: Unfolding
unfold_info | Unfolding -> Bool
isCompulsoryUnfolding Unfolding
unf_info Bool -> Bool -> Bool
|| Bool
show_unfold
                 = TidyEnv -> Expr Id -> Unfolding -> Unfolding
tidyTopUnfolding TidyEnv
rhs_tidy_env Expr Id
tidy_rhs Unfolding
unf_info
                 | Bool
otherwise
                 = Unfolding
minimal_unfold_info
     -- NB: use `orig_rhs` not `tidy_rhs` in this call to mkFinalUnfolding
     -- else you get a black hole (#22122). Reason: mkFinalUnfolding
     -- looks at IdInfo, and that is knot-tied in tidyTopBind (the Rec case)

    --------- Arity ------------
    -- Usually the Id will have an accurate arity on it, because
    -- the simplifier has just run, but not always.
    -- One case I found was when the last thing the simplifier
    -- did was to let-bind a non-atomic argument and then float
    -- it to the top level. So it seems more robust just to
    -- fix it here.
    arity :: Arity
arity = Expr Id -> Arity
exprArity Expr Id
orig_rhs Arity -> Arity -> Arity
forall a. Ord a => a -> a -> a
`min` Type -> Arity
typeArity Type
rhs_ty
            -- orig_rhs: using tidy_rhs would make a black hole, since
            --           exprArity uses the arities of Ids inside the rhs
            --
            -- typeArity: see Note [Arity invariants for bindings]
            --            in GHC.Core.Opt.Arity

------------ Unfolding  --------------
tidyTopUnfolding :: TidyEnv -> CoreExpr -> Unfolding -> Unfolding
tidyTopUnfolding :: TidyEnv -> Expr Id -> Unfolding -> Unfolding
tidyTopUnfolding TidyEnv
_ Expr Id
_ Unfolding
NoUnfolding   = Unfolding
NoUnfolding
tidyTopUnfolding TidyEnv
_ Expr Id
_ Unfolding
BootUnfolding = Unfolding
BootUnfolding
tidyTopUnfolding TidyEnv
_ Expr Id
_ (OtherCon {}) = Unfolding
evaldUnfolding

tidyTopUnfolding TidyEnv
tidy_env Expr Id
_ df :: Unfolding
df@(DFunUnfolding { df_bndrs :: Unfolding -> [Id]
df_bndrs = [Id]
bndrs, df_args :: Unfolding -> [Expr Id]
df_args = [Expr Id]
args })
  = Unfolding
df { df_bndrs = bndrs', df_args = map (tidyExpr tidy_env') args }
  where
    (TidyEnv
tidy_env', [Id]
bndrs') = TidyEnv -> [Id] -> (TidyEnv, [Id])
tidyBndrs TidyEnv
tidy_env [Id]
bndrs

tidyTopUnfolding TidyEnv
tidy_env Expr Id
tidy_rhs
     unf :: Unfolding
unf@(CoreUnfolding { uf_tmpl :: Unfolding -> Expr Id
uf_tmpl = Expr Id
unf_rhs, uf_src :: Unfolding -> UnfoldingSource
uf_src = UnfoldingSource
src  })
  = -- See Note [tidyTopUnfolding: avoiding black holes]
    Unfolding
unf { uf_tmpl = tidy_unf_rhs }
  where
    tidy_unf_rhs :: Expr Id
tidy_unf_rhs | UnfoldingSource -> Bool
isStableSource UnfoldingSource
src
                 = TidyEnv -> Expr Id -> Expr Id
tidyExpr TidyEnv
tidy_env Expr Id
unf_rhs    -- Preserves OccInfo in unf_rhs
                 | Bool
otherwise
                 = Expr Id -> Expr Id
occurAnalyseExpr Expr Id
tidy_rhs    -- Do occ-anal

{- Note [tidyTopUnfolding: avoiding black holes]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
When we are exposing all unfoldings we don't want to tidy the unfolding
twice -- we just want to use the tidied RHS.  That tidied RHS itself
contains fully-tidied Ids -- it is knot-tied.  So the uf_tmpl for the
unfolding contains stuff we can't look at.  Now consider (#22112)
   foo = foo
If we freshly compute the uf_is_value field for foo's unfolding,
we'll call `exprIsValue`, which will look at foo's unfolding!
Whether or not the RHS is a value depends on whether foo is a value...
black hole.

In the Simplifier we deal with this by not giving `foo` an unfolding
in its own RHS.  And we could do that here.  But it's qite nice
to common everything up to a single Id for foo, used everywhere.

And it's not too hard: simply leave the unfolding undisturbed, except
tidy the uf_tmpl field. Hence tidyTopUnfolding does
   unf { uf_tmpl = tidy_unf_rhs }

Don't mess with uf_is_value, or guidance; in particular don't recompute
them from tidy_unf_rhs.

And (unlike tidyNestedUnfolding) don't deep-seq the new unfolding,
because that'll cause a black hole (I /think/ because occurAnalyseExpr
looks in IdInfo).


************************************************************************
*                                                                      *
                  Old, dead, type-trimming code
*                                                                      *
************************************************************************

We used to try to "trim off" the constructors of data types that are
not exported, to reduce the size of interface files, at least without
-O.  But that is not always possible: see the old Note [When we can't
trim types] below for exceptions.

Then (#7445) I realised that the TH problem arises for any data type
that we have deriving( Data ), because we can invoke
   Language.Haskell.TH.Quote.dataToExpQ
to get a TH Exp representation of a value built from that data type.
You don't even need {-# LANGUAGE TemplateHaskell #-}.

At this point I give up. The pain of trimming constructors just
doesn't seem worth the gain.  So I've dumped all the code, and am just
leaving it here at the end of the module in case something like this
is ever resurrected.


Note [When we can't trim types]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The basic idea of type trimming is to export algebraic data types
abstractly (without their data constructors) when compiling without
-O, unless of course they are explicitly exported by the user.

We always export synonyms, because they can be mentioned in the type
of an exported Id.  We could do a full dependency analysis starting
from the explicit exports, but that's quite painful, and not done for
now.

But there are some times we can't do that, indicated by the 'no_trim_types' flag.

First, Template Haskell.  Consider (#2386) this
        module M(T, makeOne) where
          data T = Yay String
          makeOne = [| Yay "Yep" |]
Notice that T is exported abstractly, but makeOne effectively exports it too!
A module that splices in $(makeOne) will then look for a declaration of Yay,
so it'd better be there.  Hence, brutally but simply, we switch off type
constructor trimming if TH is enabled in this module.

Second, data kinds.  Consider (#5912)
     {-# LANGUAGE DataKinds #-}
     module M() where
     data UnaryTypeC a = UnaryDataC a
     type Bug = 'UnaryDataC
We always export synonyms, so Bug is exposed, and that means that
UnaryTypeC must be too, even though it's not explicitly exported.  In
effect, DataKinds means that we'd need to do a full dependency analysis
to see what data constructors are mentioned.  But we don't do that yet.

In these two cases we just switch off type trimming altogether.

mustExposeTyCon :: Bool         -- Type-trimming flag
                -> NameSet      -- Exports
                -> TyCon        -- The tycon
                -> Bool         -- Can its rep be hidden?
-- We are compiling without -O, and thus trying to write as little as
-- possible into the interface file.  But we must expose the details of
-- any data types whose constructors or fields are exported
mustExposeTyCon no_trim_types exports tc
  | no_trim_types               -- See Note [When we can't trim types]
  = True

  | not (isAlgTyCon tc)         -- Always expose synonyms (otherwise we'd have to
                                -- figure out whether it was mentioned in the type
                                -- of any other exported thing)
  = True

  | isEnumerationTyCon tc       -- For an enumeration, exposing the constructors
  = True                        -- won't lead to the need for further exposure

  | isFamilyTyCon tc            -- Open type family
  = True

  -- Below here we just have data/newtype decls or family instances

  | null data_cons              -- Ditto if there are no data constructors
  = True                        -- (NB: empty data types do not count as enumerations
                                -- see Note [Enumeration types] in GHC.Core.TyCon

  | any exported_con data_cons  -- Expose rep if any datacon or field is exported
  = True

  | isNewTyCon tc && isFFITy (snd (newTyConRhs tc))
  = True   -- Expose the rep for newtypes if the rep is an FFI type.
           -- For a very annoying reason.  'Foreign import' is meant to
           -- be able to look through newtypes transparently, but it
           -- can only do that if it can "see" the newtype representation

  | otherwise
  = False
  where
    data_cons = tyConDataCons tc
    exported_con con = any (`elemNameSet` exports)
                           (dataConName con : dataConFieldLabels con)
-}