diff options
| author | Ben Gamari <ben@smart-cactus.org> | 2020-03-24 13:13:43 -0400 |
|---|---|---|
| committer | Ben Gamari <ben@smart-cactus.org> | 2020-12-14 13:37:09 -0500 |
| commit | 7e9debd4ceb068effe8ac81892d2cabcb8f55850 (patch) | |
| tree | f222f3f3e5d662a12ab00fcb1a81d8e8dfb6c0de /testsuite/tests/printer/T18052a.stderr | |
| parent | c696bb2f4476e0ce4071e0d91687c1fe84405599 (diff) | |
| download | haskell-7e9debd4ceb068effe8ac81892d2cabcb8f55850.tar.gz | |
Optimise nullary type constructor usage
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 'testsuite/tests/printer/T18052a.stderr')
| -rw-r--r-- | testsuite/tests/printer/T18052a.stderr | 6 |
1 files changed, 3 insertions, 3 deletions
diff --git a/testsuite/tests/printer/T18052a.stderr b/testsuite/tests/printer/T18052a.stderr index 582a14a32c..28c96670cd 100644 --- a/testsuite/tests/printer/T18052a.stderr +++ b/testsuite/tests/printer/T18052a.stderr @@ -10,9 +10,9 @@ Dependent packages: [base-4.16.0.0, ghc-bignum-1.0, ghc-prim-0.8.0] ==================== Tidy Core ==================== Result size of Tidy Core - = {terms: 24, types: 61, coercions: 0, joins: 0/0} + = {terms: 24, types: 52, coercions: 0, joins: 0/0} --- RHS size: {terms: 7, types: 8, coercions: 0, joins: 0/0} +-- RHS size: {terms: 7, types: 6, coercions: 0, joins: 0/0} T18052a.$b:||: :: forall {a} {b}. a -> b -> (a, b) [GblId, Arity=2, Unf=OtherCon []] T18052a.$b:||: = \ (@a) (@b) (x :: a) (y :: b) -> (x, y) @@ -22,7 +22,7 @@ T18052a.$b:||: = \ (@a) (@b) (x :: a) (y :: b) -> (x, y) [GblId] (+++) = ++ --- RHS size: {terms: 13, types: 20, coercions: 0, joins: 0/0} +-- RHS size: {terms: 13, types: 18, coercions: 0, joins: 0/0} T18052a.$m:||: :: forall {rep :: GHC.Types.RuntimeRep} {r :: TYPE rep} {a} {b}. (a, b) -> (a -> b -> r) -> ((# #) -> r) -> r |