Marge Bot pushed to branch master at Glasgow Haskell Compiler / GHC
Commits:
101fab6e by Sebastian Graf at 2020-04-09T23:11:21-04:00
Special case `isConstraintKindCon` on `AlgTyCon`
Previously, the `tyConUnique` record selector would unfold into a huge
case expression that would be inlined in all call sites, such as the
`INLINE`-annotated `coreView`, see #18026. `constraintKindTyConKey` only
occurs as the `Unique` of an `AlgTyCon` anyway, so we can make the code
a lot more compact, but have to move it to GHC.Core.TyCon.
Metric Decrease:
T12150
T12234
- - - - -
3 changed files:
- compiler/GHC/Core/TyCon.hs
- compiler/GHC/Core/Type.hs
- compiler/prelude/TysWiredIn.hs
Changes:
=====================================
compiler/GHC/Core/TyCon.hs
=====================================
@@ -45,7 +45,7 @@ module GHC.Core.TyCon(
noTcTyConScopedTyVars,
-- ** Predicates on TyCons
- isAlgTyCon, isVanillaAlgTyCon,
+ isAlgTyCon, isVanillaAlgTyCon, isConstraintKindCon,
isClassTyCon, isFamInstTyCon,
isFunTyCon,
isPrimTyCon,
@@ -1868,6 +1868,15 @@ isVanillaAlgTyCon :: TyCon -> Bool
isVanillaAlgTyCon (AlgTyCon { algTcParent = VanillaAlgTyCon _ }) = True
isVanillaAlgTyCon _ = False
+-- | Returns @True@ for the 'TyCon' of the 'Constraint' kind.
+isConstraintKindCon :: TyCon -> Bool
+-- NB: We intentionally match on AlgTyCon, because 'constraintKindTyCon' is
+-- always an AlgTyCon (see 'pcTyCon' in TysWiredIn) and the record selector
+-- for 'tyConUnique' would generate unreachable code for every other data
+-- constructor of TyCon (see #18026).
+isConstraintKindCon AlgTyCon { tyConUnique = u } = u == constraintKindTyConKey
+isConstraintKindCon _ = False
+
isDataTyCon :: TyCon -> Bool
-- ^ Returns @True@ for data types that are /definitely/ represented by
-- heap-allocated constructors. These are scrutinised by Core-level
=====================================
compiler/GHC/Core/Type.hs
=====================================
@@ -2924,9 +2924,6 @@ distinct uniques, they are treated as equal at all times except
during type inference.
-}
-isConstraintKindCon :: TyCon -> Bool
-isConstraintKindCon tc = tyConUnique tc == constraintKindTyConKey
-
-- | Tests whether the given kind (which should look like @TYPE x@)
-- is something other than a constructor tree (that is, constructors at every node).
-- E.g. True of TYPE k, TYPE (F Int)
=====================================
compiler/prelude/TysWiredIn.hs
=====================================
@@ -639,6 +639,7 @@ typeNatKind = mkTyConTy typeNatKindCon
typeSymbolKind = mkTyConTy typeSymbolKindCon
constraintKindTyCon :: TyCon
+-- 'TyCon.isConstraintKindCon' assumes that this is an AlgTyCon!
constraintKindTyCon = pcTyCon constraintKindTyConName Nothing [] []
liftedTypeKind, typeToTypeKind, constraintKind :: Kind
View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/101fab6ee6cee72b9ffce40e45ebf39466d1c01a
--
View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/101fab6ee6cee72b9ffce40e45ebf39466d1c01a
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