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| author | Ben Gamari <ben@smart-cactus.org> | 2020-03-24 13:13:43 -0400 |
|---|---|---|
| committer | Ben Gamari <ben@smart-cactus.org> | 2020-12-14 15:22:29 -0500 |
| commit | dad87210efffce9cfc2d17dc088a71d9dea14535 (patch) | |
| tree | 42e1c3cb031775598afce272e7caca4c578a20f2 /compiler/GHC/Builtin | |
| parent | af855ac1d37359df3db8c48dc6c9dd2f3fe24e77 (diff) | |
| download | haskell-dad87210efffce9cfc2d17dc088a71d9dea14535.tar.gz | |
Optimise nullary type constructor usagewip/tyconapp-opts
During the compilation of programs GHC very frequently deals with
the `Type` type, which is a synonym of `TYPE 'LiftedRep`. This patch
teaches GHC to avoid expanding the `Type` synonym (and other nullary
type synonyms) during type comparisons, saving a good amount of work.
This optimisation is described in `Note [Comparing nullary type
synonyms]`.
To maximize the impact of this optimisation, we introduce a few
special-cases to reduce `TYPE 'LiftedRep` to `Type`. See
`Note [Prefer Type over TYPE 'LiftedPtrRep]`.
Closes #17958.
Metric Decrease:
T18698b
T1969
T12227
T12545
T12707
T14683
T3064
T5631
T5642
T9020
T9630
T9872a
T13035
haddock.Cabal
haddock.base
Diffstat (limited to 'compiler/GHC/Builtin')
| -rw-r--r-- | compiler/GHC/Builtin/Types.hs | 9 | ||||
| -rw-r--r-- | compiler/GHC/Builtin/Types/Prim.hs | 4 | ||||
| -rw-r--r-- | compiler/GHC/Builtin/Types/Prim.hs-boot | 5 |
3 files changed, 11 insertions, 7 deletions
diff --git a/compiler/GHC/Builtin/Types.hs b/compiler/GHC/Builtin/Types.hs index d06bc4a12b..3339e0a020 100644 --- a/compiler/GHC/Builtin/Types.hs +++ b/compiler/GHC/Builtin/Types.hs @@ -170,6 +170,7 @@ import GHC.Types.Var (VarBndr (Bndr)) import GHC.Settings.Constants ( mAX_TUPLE_SIZE, mAX_CTUPLE_SIZE, mAX_SUM_SIZE ) import GHC.Unit.Module ( Module ) import GHC.Core.Type +import qualified GHC.Core.TyCo.Rep as TyCoRep (Type(TyConApp)) import GHC.Types.RepType import GHC.Core.DataCon import GHC.Core.ConLike @@ -688,8 +689,9 @@ constraintKindTyCon :: TyCon -- 'TyCon.isConstraintKindCon' assumes that this is an AlgTyCon! constraintKindTyCon = pcTyCon constraintKindTyConName Nothing [] [] +-- See Note [Prefer Type over TYPE 'LiftedRep] in GHC.Core.TyCo.Rep. liftedTypeKind, typeToTypeKind, constraintKind :: Kind -liftedTypeKind = tYPE liftedRepTy +liftedTypeKind = TyCoRep.TyConApp liftedTypeKindTyCon [] typeToTypeKind = liftedTypeKind `mkVisFunTyMany` liftedTypeKind constraintKind = mkTyConApp constraintKindTyCon [] @@ -1410,11 +1412,12 @@ runtimeRepTy :: Type runtimeRepTy = mkTyConTy runtimeRepTyCon -- Type synonyms; see Note [TYPE and RuntimeRep] in GHC.Builtin.Types.Prim +-- and Note [Prefer Type over TYPE 'LiftedRep] in GHC.Core.TyCo.Rep. -- type Type = tYPE 'LiftedRep liftedTypeKindTyCon :: TyCon liftedTypeKindTyCon = buildSynTyCon liftedTypeKindTyConName - [] liftedTypeKind [] - (tYPE liftedRepTy) + [] liftedTypeKind [] rhs + where rhs = TyCoRep.TyConApp tYPETyCon [liftedRepTy] runtimeRepTyCon :: TyCon runtimeRepTyCon = pcTyCon runtimeRepTyConName Nothing [] diff --git a/compiler/GHC/Builtin/Types/Prim.hs b/compiler/GHC/Builtin/Types/Prim.hs index fc74596e45..61f341a0bb 100644 --- a/compiler/GHC/Builtin/Types/Prim.hs +++ b/compiler/GHC/Builtin/Types/Prim.hs @@ -551,10 +551,6 @@ mkPrimTcName built_in_syntax occ key tycon = mkWiredInName gHC_PRIM (mkTcOccFS occ) key (mkATyCon tycon) built_in_syntax ----------------------------- --- | Given a RuntimeRep, applies TYPE to it. --- see Note [TYPE and RuntimeRep] -tYPE :: Type -> Type -tYPE rr = TyConApp tYPETyCon [rr] -- Given a Multiplicity, applies FUN to it. functionWithMultiplicity :: Type -> Type diff --git a/compiler/GHC/Builtin/Types/Prim.hs-boot b/compiler/GHC/Builtin/Types/Prim.hs-boot new file mode 100644 index 0000000000..28326fcc8b --- /dev/null +++ b/compiler/GHC/Builtin/Types/Prim.hs-boot @@ -0,0 +1,5 @@ +module GHC.Builtin.Types.Prim where + +import GHC.Core.TyCon + +tYPETyCon :: TyCon |