[Git][ghc/ghc][master] 2 commits: Fix binder-swap bug
Marge Bot (@marge-bot)
gitlab at gitlab.haskell.org
Tue Oct 25 22:07:28 UTC 2022
Marge Bot pushed to branch master at Glasgow Haskell Compiler / GHC
Commits:
41406da5 by Simon Peyton Jones at 2022-10-25T18:07:03-04:00
Fix binder-swap bug
This patch fixes #21229 properly, by avoiding doing a
binder-swap on dictionary Ids. This is pretty subtle, and explained
in Note [Care with binder-swap on dictionaries].
Test is already in simplCore/should_run/T21229
This allows us to restore a feature to the specialiser that we had
to revert: see Note [Specialising polymorphic dictionaries].
(This is done in a separate patch.)
I also modularised things, using a new function scrutBinderSwap_maybe
in all the places where we are (effectively) doing a binder-swap,
notably
* Simplify.Iteration.addAltUnfoldings
* SpecConstr.extendCaseBndrs
In Simplify.Iteration.addAltUnfoldings I also eliminated a guard
Many <- idMult case_bndr
because we concluded, in #22123, that it was doing no good.
- - - - -
5a997e16 by Simon Peyton Jones at 2022-10-25T18:07:03-04:00
Make the specialiser handle polymorphic specialisation
Ticket #13873 unexpectedly showed that a SPECIALISE pragma made a
program run (a lot) slower, because less specialisation took place
overall. It turned out that the specialiser was missing opportunities
because of quantified type variables.
It was quite easy to fix. The story is given in
Note [Specialising polymorphic dictionaries]
Two other minor fixes in the specialiser
* There is no benefit in specialising data constructor /wrappers/.
(They can appear overloaded because they are given a dictionary
to store in the constructor.) Small guard in canSpecImport.
* There was a buglet in the UnspecArg case of specHeader, in the
case where there is a dead binder. We need a LitRubbish filler
for the specUnfolding stuff. I expanded
Note [Drop dead args from specialisations] to explain.
There is a 4% increase in compile time for T15164, because we generate
more specialised code. This seems OK.
Metric Increase:
T15164
- - - - -
12 changed files:
- compiler/GHC/Core/Opt/OccurAnal.hs
- compiler/GHC/Core/Opt/SetLevels.hs
- compiler/GHC/Core/Opt/Simplify/Env.hs
- compiler/GHC/Core/Opt/Simplify/Iteration.hs
- compiler/GHC/Core/Opt/SpecConstr.hs
- compiler/GHC/Core/Opt/Specialise.hs
- compiler/GHC/Core/Subst.hs
- compiler/GHC/Core/Type.hs
- testsuite/tests/linters/notes.stdout
- testsuite/tests/numeric/should_compile/T19641.stderr
- testsuite/tests/simplCore/should_compile/T8331.stderr
- testsuite/tests/simplCore/should_compile/all.T
Changes:
=====================================
compiler/GHC/Core/Opt/OccurAnal.hs
=====================================
@@ -19,7 +19,7 @@ core expression with (hopefully) improved usage information.
module GHC.Core.Opt.OccurAnal (
occurAnalysePgm,
occurAnalyseExpr,
- zapLambdaBndrs
+ zapLambdaBndrs, scrutBinderSwap_maybe
) where
import GHC.Prelude hiding ( head, init, last, tail )
@@ -27,11 +27,12 @@ import GHC.Prelude hiding ( head, init, last, tail )
import GHC.Core
import GHC.Core.FVs
import GHC.Core.Utils ( exprIsTrivial, isDefaultAlt, isExpandableApp,
- stripTicksTopE, mkTicks )
+ mkCastMCo, mkTicks )
import GHC.Core.Opt.Arity ( joinRhsArity, isOneShotBndr )
import GHC.Core.Coercion
+import GHC.Core.Predicate ( isDictId )
import GHC.Core.Type
-import GHC.Core.TyCo.FVs( tyCoVarsOfMCo )
+import GHC.Core.TyCo.FVs ( tyCoVarsOfMCo )
import GHC.Data.Maybe( isJust, orElse )
import GHC.Data.Graph.Directed ( SCC(..), Node(..)
@@ -2464,8 +2465,8 @@ data OccEnv
-- See Note [The binder-swap substitution]
-- If x :-> (y, co) is in the env,
- -- then please replace x by (y |> sym mco)
- -- Invariant of course: idType x = exprType (y |> sym mco)
+ -- then please replace x by (y |> mco)
+ -- Invariant of course: idType x = exprType (y |> mco)
, occ_bs_env :: !(VarEnv (OutId, MCoercion))
, occ_bs_rng :: !VarSet -- Vars free in the range of occ_bs_env
-- Domain is Global and Local Ids
@@ -2671,7 +2672,7 @@ The binder-swap is implemented by the occ_bs_env field of OccEnv.
There are two main pieces:
* Given case x |> co of b { alts }
- we add [x :-> (b, co)] to the occ_bs_env environment; this is
+ we add [x :-> (b, sym co)] to the occ_bs_env environment; this is
done by addBndrSwap.
* Then, at an occurrence of a variable, we look up in the occ_bs_env
@@ -2739,30 +2740,8 @@ Some tricky corners:
(BS5) We have to apply the occ_bs_env substitution uniformly,
including to (local) rules and unfoldings.
-Historical note
----------------
-We used to do the binder-swap transformation by introducing
-a proxy let-binding, thus;
-
- case x of b { pi -> ri }
- ==>
- case x of b { pi -> let x = b in ri }
-
-But that had two problems:
-
-1. If 'x' is an imported GlobalId, we'd end up with a GlobalId
- on the LHS of a let-binding which isn't allowed. We worked
- around this for a while by "localising" x, but it turned
- out to be very painful #16296,
-
-2. In CorePrep we use the occurrence analyser to do dead-code
- elimination (see Note [Dead code in CorePrep]). But that
- occasionally led to an unlifted let-binding
- case x of b { DEFAULT -> let x::Int# = b in ... }
- which disobeys one of CorePrep's output invariants (no unlifted
- let-bindings) -- see #5433.
-
-Doing a substitution (via occ_bs_env) is much better.
+(BS6) We must be very careful with dictionaries.
+ See Note [Care with binder-swap on dictionaries]
Note [Case of cast]
~~~~~~~~~~~~~~~~~~~
@@ -2772,6 +2751,54 @@ We'd like to eliminate the inner case. That is the motivation for
equation (2) in Note [Binder swap]. When we get to the inner case, we
inline x, cancel the casts, and away we go.
+Note [Care with binder-swap on dictionaries]
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+This Note explains why we need isDictId in scrutBinderSwap_maybe.
+Consider this tricky example (#21229, #21470):
+
+ class Sing (b :: Bool) where sing :: Bool
+ instance Sing 'True where sing = True
+ instance Sing 'False where sing = False
+
+ f :: forall a. Sing a => blah
+
+ h = \ @(a :: Bool) ($dSing :: Sing a)
+ let the_co = Main.N:Sing[0] <a> :: Sing a ~R# Bool
+ case ($dSing |> the_co) of wild
+ True -> f @'True (True |> sym the_co)
+ False -> f @a dSing
+
+Now do a binder-swap on the case-expression:
+
+ h = \ @(a :: Bool) ($dSing :: Sing a)
+ let the_co = Main.N:Sing[0] <a> :: Sing a ~R# Bool
+ case ($dSing |> the_co) of wild
+ True -> f @'True (True |> sym the_co)
+ False -> f @a (wild |> sym the_co)
+
+And now substitute `False` for `wild` (since wild=False in the False branch):
+
+ h = \ @(a :: Bool) ($dSing :: Sing a)
+ let the_co = Main.N:Sing[0] <a> :: Sing a ~R# Bool
+ case ($dSing |> the_co) of wild
+ True -> f @'True (True |> sym the_co)
+ False -> f @a (False |> sym the_co)
+
+And now we have a problem. The specialiser will specialise (f @a d)a (for all
+vtypes a and dictionaries d!!) with the dictionary (False |> sym the_co), using
+Note [Specialising polymorphic dictionaries] in GHC.Core.Opt.Specialise.
+
+The real problem is the binder-swap. It swaps a dictionary variable $dSing
+(of kind Constraint) for a term variable wild (of kind Type). And that is
+dangerous: a dictionary is a /singleton/ type whereas a general term variable is
+not. In this particular example, Bool is most certainly not a singleton type!
+
+Conclusion:
+ for a /dictionary variable/ do not perform
+ the clever cast version of the binder-swap
+
+Hence the subtle isDictId in scrutBinderSwap_maybe.
+
Note [Zap case binders in proxy bindings]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
From the original
@@ -2786,8 +2813,87 @@ binding x = cb. See #5028.
NB: the OccInfo on /occurrences/ really doesn't matter much; the simplifier
doesn't use it. So this is only to satisfy the perhaps-over-picky Lint.
+-}
+
+addBndrSwap :: OutExpr -> Id -> OccEnv -> OccEnv
+-- See Note [The binder-swap substitution]
+addBndrSwap scrut case_bndr
+ env@(OccEnv { occ_bs_env = swap_env, occ_bs_rng = rng_vars })
+ | Just (scrut_var, mco) <- scrutBinderSwap_maybe scrut
+ , scrut_var /= case_bndr
+ -- Consider: case x of x { ... }
+ -- Do not add [x :-> x] to occ_bs_env, else lookupBndrSwap will loop
+ = env { occ_bs_env = extendVarEnv swap_env scrut_var (case_bndr', mco)
+ , occ_bs_rng = rng_vars `extendVarSet` case_bndr'
+ `unionVarSet` tyCoVarsOfMCo mco }
+
+ | otherwise
+ = env
+ where
+ case_bndr' = zapIdOccInfo case_bndr
+ -- See Note [Zap case binders in proxy bindings]
+
+scrutBinderSwap_maybe :: OutExpr -> Maybe (OutVar, MCoercion)
+-- If (scrutBinderSwap_maybe e = Just (v, mco), then
+-- v = e |> mco
+-- See Note [Case of cast]
+-- See Note [Care with binder-swap on dictionaries]
+--
+-- We use this same function in SpecConstr, and Simplify.Iteration,
+-- when something binder-swap-like is happening
+scrutBinderSwap_maybe (Var v) = Just (v, MRefl)
+scrutBinderSwap_maybe (Cast (Var v) co)
+ | not (isDictId v) = Just (v, MCo (mkSymCo co))
+ -- Cast: see Note [Case of cast]
+ -- isDictId: see Note [Care with binder-swap on dictionaries]
+ -- The isDictId rejects a Constraint/Constraint binder-swap, perhaps
+ -- over-conservatively. But I have never seen one, so I'm leaving
+ -- the code as simple as possible. Losing the binder-swap in a
+ -- rare case probably has very low impact.
+scrutBinderSwap_maybe (Tick _ e) = scrutBinderSwap_maybe e -- Drop ticks
+scrutBinderSwap_maybe _ = Nothing
+
+lookupBndrSwap :: OccEnv -> Id -> (CoreExpr, Id)
+-- See Note [The binder-swap substitution]
+-- Returns an expression of the same type as Id
+lookupBndrSwap env@(OccEnv { occ_bs_env = bs_env }) bndr
+ = case lookupVarEnv bs_env bndr of {
+ Nothing -> (Var bndr, bndr) ;
+ Just (bndr1, mco) ->
+
+ -- Why do we iterate here?
+ -- See (BS2) in Note [The binder-swap substitution]
+ case lookupBndrSwap env bndr1 of
+ (fun, fun_id) -> (mkCastMCo fun mco, fun_id) }
+
+
+{- Historical note [Proxy let-bindings]
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+We used to do the binder-swap transformation by introducing
+a proxy let-binding, thus;
+
+ case x of b { pi -> ri }
+ ==>
+ case x of b { pi -> let x = b in ri }
+
+But that had two problems:
+
+1. If 'x' is an imported GlobalId, we'd end up with a GlobalId
+ on the LHS of a let-binding which isn't allowed. We worked
+ around this for a while by "localising" x, but it turned
+ out to be very painful #16296,
+
+2. In CorePrep we use the occurrence analyser to do dead-code
+ elimination (see Note [Dead code in CorePrep]). But that
+ occasionally led to an unlifted let-binding
+ case x of b { DEFAULT -> let x::Int# = b in ... }
+ which disobeys one of CorePrep's output invariants (no unlifted
+ let-bindings) -- see #5433.
+
+Doing a substitution (via occ_bs_env) is much better.
+
Historical Note [no-case-of-case]
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
We *used* to suppress the binder-swap in case expressions when
-fno-case-of-case is on. Old remarks:
"This happens in the first simplifier pass,
@@ -2846,53 +2952,8 @@ binder-swap in OccAnal:
It's fixed by doing the binder-swap in OccAnal because we can do the
binder-swap unconditionally and still get occurrence analysis
information right.
--}
-addBndrSwap :: OutExpr -> Id -> OccEnv -> OccEnv
--- See Note [The binder-swap substitution]
-addBndrSwap scrut case_bndr
- env@(OccEnv { occ_bs_env = swap_env, occ_bs_rng = rng_vars })
- | Just (scrut_var, mco) <- get_scrut_var (stripTicksTopE (const True) scrut)
- , scrut_var /= case_bndr
- -- Consider: case x of x { ... }
- -- Do not add [x :-> x] to occ_bs_env, else lookupBndrSwap will loop
- = env { occ_bs_env = extendVarEnv swap_env scrut_var (case_bndr', mco)
- , occ_bs_rng = rng_vars `extendVarSet` case_bndr'
- `unionVarSet` tyCoVarsOfMCo mco }
-
- | otherwise
- = env
- where
- get_scrut_var :: OutExpr -> Maybe (OutVar, MCoercion)
- get_scrut_var (Var v) = Just (v, MRefl)
- get_scrut_var (Cast (Var v) co) = Just (v, MCo co) -- See Note [Case of cast]
- get_scrut_var _ = Nothing
-
- case_bndr' = zapIdOccInfo case_bndr
- -- See Note [Zap case binders in proxy bindings]
-lookupBndrSwap :: OccEnv -> Id -> (CoreExpr, Id)
--- See Note [The binder-swap substitution]
--- Returns an expression of the same type as Id
-lookupBndrSwap env@(OccEnv { occ_bs_env = bs_env }) bndr
- = case lookupVarEnv bs_env bndr of {
- Nothing -> (Var bndr, bndr) ;
- Just (bndr1, mco) ->
-
- -- Why do we iterate here?
- -- See (BS2) in Note [The binder-swap substitution]
- case lookupBndrSwap env bndr1 of
- (fun, fun_id) -> (add_cast fun mco, fun_id) }
-
- where
- add_cast fun MRefl = fun
- add_cast fun (MCo co) = Cast fun (mkSymCo co)
- -- We must switch that 'co' to 'sym co';
- -- see the comment with occ_bs_env
- -- No need to test for isReflCo, because 'co' came from
- -- a (Cast e co) and hence is unlikely to be Refl
-
-{-
************************************************************************
* *
\subsection[OccurAnal-types]{OccEnv}
=====================================
compiler/GHC/Core/Opt/SetLevels.hs
=====================================
@@ -51,17 +51,6 @@
The simplifier tries to get rid of occurrences of x, in favour of wild,
in the hope that there will only be one remaining occurrence of x, namely
the scrutinee of the case, and we can inline it.
-
- This can only work if @wild@ is an unrestricted binder. Indeed, even with the
- extended typing rule (in the linter) for case expressions, if
- case x of wild % 1 { p -> e}
- is well-typed, then
- case x of wild % 1 { p -> e[wild\x] }
- is only well-typed if @e[wild\x] = e@ (that is, if @wild@ is not used in @e@
- at all). In which case, it is, of course, pointless to do the substitution
- anyway. So for a linear binder (and really anything which isn't unrestricted),
- doing this substitution would either produce ill-typed terms or be the
- identity.
-}
module GHC.Core.Opt.SetLevels (
@@ -1602,7 +1591,9 @@ extendCaseBndrEnv :: LevelEnv
-> LevelEnv
extendCaseBndrEnv le@(LE { le_subst = subst, le_env = id_env })
case_bndr (Var scrut_var)
- | Many <- varMult case_bndr
+ -- We could use OccurAnal. scrutBinderSwap_maybe here, and perhaps
+ -- get a bit more floating. But we didn't in the past and it's
+ -- an unforced change, so I'm leaving it.
= le { le_subst = extendSubstWithVar subst case_bndr scrut_var
, le_env = add_id id_env (case_bndr, scrut_var) }
extendCaseBndrEnv env _ _ = env
=====================================
compiler/GHC/Core/Opt/Simplify/Env.hs
=====================================
@@ -71,7 +71,8 @@ import GHC.Core.Make ( mkWildValBinder, mkCoreLet )
import GHC.Builtin.Types
import GHC.Core.TyCo.Rep ( TyCoBinder(..) )
import qualified GHC.Core.Type as Type
-import GHC.Core.Type hiding ( substTy, substTyVar, substTyVarBndr, extendTvSubst, extendCvSubst )
+import GHC.Core.Type hiding ( substTy, substTyVar, substTyVarBndr, substCo
+ , extendTvSubst, extendCvSubst )
import qualified GHC.Core.Coercion as Coercion
import GHC.Core.Coercion hiding ( substCo, substCoVar, substCoVarBndr )
import GHC.Platform ( Platform )
=====================================
compiler/GHC/Core/Opt/Simplify/Iteration.hs
=====================================
@@ -22,7 +22,7 @@ import GHC.Core.Opt.Simplify.Monad
import GHC.Core.Type hiding ( substTy, substTyVar, extendTvSubst, extendCvSubst )
import GHC.Core.Opt.Simplify.Env
import GHC.Core.Opt.Simplify.Utils
-import GHC.Core.Opt.OccurAnal ( occurAnalyseExpr, zapLambdaBndrs )
+import GHC.Core.Opt.OccurAnal ( occurAnalyseExpr, zapLambdaBndrs, scrutBinderSwap_maybe )
import GHC.Core.Make ( FloatBind, mkImpossibleExpr, castBottomExpr )
import qualified GHC.Core.Make
import GHC.Core.Coercion hiding ( substCo, substCoVar )
@@ -3286,19 +3286,21 @@ zapIdOccInfoAndSetEvald str v =
-- see Note [Case alternative occ info]
addAltUnfoldings :: SimplEnv -> Maybe OutExpr -> OutId -> OutExpr -> SimplM SimplEnv
-addAltUnfoldings env scrut case_bndr con_app
+addAltUnfoldings env mb_scrut case_bndr con_app
= do { let con_app_unf = mk_simple_unf con_app
env1 = addBinderUnfolding env case_bndr con_app_unf
-- See Note [Add unfolding for scrutinee]
- env2 | Many <- idMult case_bndr = case scrut of
- Just (Var v) -> addBinderUnfolding env1 v con_app_unf
- Just (Cast (Var v) co) -> addBinderUnfolding env1 v $
- mk_simple_unf (Cast con_app (mkSymCo co))
- _ -> env1
+ env2 | Just scrut <- mb_scrut
+ , Just (v,mco) <- scrutBinderSwap_maybe scrut
+ = addBinderUnfolding env1 v $
+ if isReflMCo mco -- isReflMCo: avoid calling mk_simple_unf
+ then con_app_unf -- twice in the common case
+ else mk_simple_unf (mkCastMCo con_app mco)
+
| otherwise = env1
- ; traceSmpl "addAltUnf" (vcat [ppr case_bndr <+> ppr scrut, ppr con_app])
+ ; traceSmpl "addAltUnf" (vcat [ppr case_bndr <+> ppr mb_scrut, ppr con_app])
; return env2 }
where
-- Force the opts, so that the whole SimplEnv isn't retained
@@ -3361,9 +3363,6 @@ it's also good for case-elimination -- suppose that 'f' was inlined
and did multi-level case analysis, then we'd solve it in one
simplifier sweep instead of two.
-Exactly the same issue arises in GHC.Core.Opt.SpecConstr;
-see Note [Add scrutinee to ValueEnv too] in GHC.Core.Opt.SpecConstr
-
HOWEVER, given
case x of y { Just a -> r1; Nothing -> r2 }
we do not want to add the unfolding x -> y to 'x', which might seem cool,
@@ -3374,8 +3373,11 @@ piece of information.
So instead we add the unfolding x -> Just a, and x -> Nothing in the
respective RHSs.
-Since this transformation is tantamount to a binder swap, the same caveat as in
-Note [Suppressing binder-swaps on linear case] in OccurAnal apply.
+Since this transformation is tantamount to a binder swap, we use
+GHC.Core.Opt.OccurAnal.scrutBinderSwap_maybe to do the check.
+
+Exactly the same issue arises in GHC.Core.Opt.SpecConstr;
+see Note [Add scrutinee to ValueEnv too] in GHC.Core.Opt.SpecConstr
************************************************************************
=====================================
compiler/GHC/Core/Opt/SpecConstr.hs
=====================================
@@ -35,6 +35,7 @@ import GHC.Core.Unfold
import GHC.Core.FVs ( exprsFreeVarsList, exprFreeVars )
import GHC.Core.Opt.Monad
import GHC.Core.Opt.WorkWrap.Utils
+import GHC.Core.Opt.OccurAnal( scrutBinderSwap_maybe )
import GHC.Core.DataCon
import GHC.Core.Class( classTyVars )
import GHC.Core.Coercion hiding( substCo )
@@ -1072,8 +1073,8 @@ extendCaseBndrs env scrut case_bndr con alt_bndrs
= (env2, alt_bndrs')
where
live_case_bndr = not (isDeadBinder case_bndr)
- env1 | Var v <- stripTicksTopE (const True) scrut
- = extendValEnv env v cval
+ env1 | Just (v, mco) <- scrutBinderSwap_maybe scrut
+ , isReflMCo mco = extendValEnv env v cval
| otherwise = env -- See Note [Add scrutinee to ValueEnv too]
env2 | live_case_bndr = extendValEnv env1 case_bndr cval
| otherwise = env1
@@ -1167,6 +1168,10 @@ though the simplifier has systematically replaced uses of 'x' with 'y'
and 'b' with 'c' in the code. The use of 'b' in the ValueEnv came
from outside the case. See #4908 for the live example.
+It's very like the binder-swap story, so we use scrutBinderSwap_maybe
+to identify suitable scrutinees -- but only if there is no cast
+(isReflMCo) because that's all that the ValueEnv allows.
+
Note [Avoiding exponential blowup]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The sc_count field of the ScEnv says how many times we are prepared to
=====================================
compiler/GHC/Core/Opt/Specialise.hs
=====================================
@@ -15,9 +15,7 @@ import GHC.Driver.Config
import GHC.Driver.Config.Diagnostic
import GHC.Driver.Config.Core.Rules ( initRuleOpts )
-import GHC.Tc.Utils.TcType hiding( substTy )
-
-import GHC.Core.Type hiding( substTy, extendTvSubstList, zapSubst )
+import GHC.Core.Type hiding( substTy, substCo, extendTvSubst, zapSubst )
import GHC.Core.Multiplicity
import GHC.Core.Predicate
import GHC.Core.Coercion( Coercion )
@@ -25,12 +23,15 @@ import GHC.Core.Opt.Monad
import qualified GHC.Core.Subst as Core
import GHC.Core.Unfold.Make
import GHC.Core
+import GHC.Core.Make ( mkLitRubbish )
+import GHC.Core.Unify ( tcMatchTy )
import GHC.Core.Rules
import GHC.Core.Utils ( exprIsTrivial
, mkCast, exprType
, stripTicksTop, mkInScopeSetBndrs )
import GHC.Core.FVs
-import GHC.Core.TyCo.Rep (TyCoBinder (..))
+import GHC.Core.TyCo.Rep ( TyCoBinder (..) )
+import GHC.Core.TyCo.FVs ( tyCoVarsOfTypeList )
import GHC.Core.Opt.Arity( collectBindersPushingCo )
import GHC.Builtin.Types ( unboxedUnitTy )
@@ -531,6 +532,48 @@ like
f :: Eq [(a,b)] => ...
+Note [Specialisation and overlapping instances]
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+Here is at tricky case (see a comment in MR !8916):
+
+ module A where
+ class C a where
+ meth :: a -> String
+ instance {-# OVERLAPPABLE #-} C (Maybe a) where
+ meth _ = "Maybe"
+
+ {-# SPECIALISE f :: Maybe a -> Bool -> String #-}
+ f :: C a => a -> Bool -> String
+ f a True = f a False
+ f a _ = meth a
+
+ module B where
+ import A
+
+ instance C (Maybe Int) where
+ meth _ = "Int"
+
+ main = putStrLn $ f (Just 42 :: Maybe Int) True
+
+Running main without optimisations yields "Int", the correct answer.
+Activating optimisations yields "Maybe" due to a rewrite rule in module
+A generated by the SPECIALISE pragma:
+
+ RULE "USPEC f" forall a (d :: C a). f @a d = $sf
+
+In B we get the call (f @(Maybe Int) (d :: C (Maybe Int))), and
+that rewrites to $sf, but that isn't really right.
+
+Overlapping instances mean that `C (Maybe Int)` is not a singleton
+type: there two distinct dictionaries that have this type. And that
+spells trouble for specialistion, which really asssumes singleton
+types.
+
+For now, we just accept this problem, but it may bite us one day.
+One solution would be to decline to expose any specialisation rules
+to an importing module -- but that seems a bit drastic.
+
+
************************************************************************
* *
\subsubsection{The new specialiser}
@@ -804,8 +847,12 @@ spec_import top_env callers rb dict_binds cis@(CIS fn _)
canSpecImport :: DynFlags -> Id -> Maybe CoreExpr
canSpecImport dflags fn
+ | isDataConWrapId fn
+ = Nothing -- Don't specialise data-con wrappers, even if they
+ -- have dict args; there is no benefit.
+
| CoreUnfolding { uf_tmpl = rhs } <- unf
- -- See Note [Specialising imported functions] point (1).
+ -- CoreUnfolding: see Note [Specialising imported functions] point (1).
, isAnyInlinePragma (idInlinePragma fn)
-- See Note [Specialising imported functions] point (2).
= Just rhs
@@ -1508,12 +1555,12 @@ specCalls spec_imp env dict_binds existing_rules calls_for_me fn rhs
| otherwise -- No calls or RHS doesn't fit our preconceptions
= warnPprTrace (not (exprIsTrivial rhs) && notNull calls_for_me)
- "Missed specialisation opportunity" (ppr fn $$ _trace_doc) $
+ "Missed specialisation opportunity for" (ppr fn $$ trace_doc) $
-- Note [Specialisation shape]
-- pprTrace "specCalls: none" (ppr fn <+> ppr calls_for_me) $
return ([], [], emptyUDs)
where
- _trace_doc = sep [ ppr rhs_bndrs, ppr (idInlineActivation fn) ]
+ trace_doc = sep [ ppr rhs_bndrs, ppr (idInlineActivation fn) ]
fn_type = idType fn
fn_arity = idArity fn
@@ -1577,8 +1624,16 @@ specCalls spec_imp env dict_binds existing_rules calls_for_me fn rhs
else
do { -- Run the specialiser on the specialised RHS
-- The "1" suffix is before we maybe add the void arg
- ; (spec_rhs1, rhs_uds) <- specLam rhs_env2 (spec_bndrs1 ++ leftover_bndrs) rhs_body
- ; let spec_fn_ty1 = exprType spec_rhs1
+ ; (rhs_body', rhs_uds) <- specExpr rhs_env2 rhs_body
+ -- Add the { d1' = dx1; d2' = dx2 } usage stuff
+ -- to the rhs_uds; see Note [Specialising Calls]
+ ; let rhs_uds_w_dx = foldr consDictBind rhs_uds dx_binds
+ spec_rhs_bndrs = spec_bndrs1 ++ leftover_bndrs
+ (spec_uds, dumped_dbs) = dumpUDs spec_rhs_bndrs rhs_uds_w_dx
+ spec_rhs1 = mkLams spec_rhs_bndrs $
+ wrapDictBindsE dumped_dbs rhs_body'
+
+ spec_fn_ty1 = exprType spec_rhs1
-- Maybe add a void arg to the specialised function,
-- to avoid unlifted bindings
@@ -1612,10 +1667,6 @@ specCalls spec_imp env dict_binds existing_rules calls_for_me fn rhs
herald fn rule_bndrs rule_lhs_args
(mkVarApps (Var spec_fn) spec_bndrs)
- -- Add the { d1' = dx1; d2' = dx2 } usage stuff
- -- See Note [Specialising Calls]
- spec_uds = foldr consDictBind rhs_uds dx_binds
-
simpl_opts = initSimpleOpts dflags
--------------------------------------
@@ -1798,11 +1849,23 @@ in the specialisation:
{-# RULE "SPEC f @Int" forall x. f @Int x $dShow = $sf #-}
This doesn’t save us much, since the arg would be removed later by
-worker/wrapper, anyway, but it’s easy to do. Note, however, that we
-only drop dead arguments if:
+worker/wrapper, anyway, but it’s easy to do.
- 1. We don’t specialise on them.
- 2. They come before an argument we do specialise on.
+Wrinkles
+
+* Note that we only drop dead arguments if:
+ 1. We don’t specialise on them.
+ 2. They come before an argument we do specialise on.
+ Doing the latter would require eta-expanding the RULE, which could
+ make it match less often, so it’s not worth it. Doing the former could
+ be more useful --- it would stop us from generating pointless
+ specialisations --- but it’s more involved to implement and unclear if
+ it actually provides much benefit in practice.
+
+* If the function has a stable unfolding, specHeader has to come up with
+ arguments to pass to that stable unfolding, when building the stable
+ unfolding of the specialised function: this is the last field in specHeader's
+ big result tuple.
The right thing to do is to produce a LitRubbish; it should rapidly
disappear. Rather like GHC.Core.Opt.WorkWrap.Utils.mk_absent_let.
@@ -2253,11 +2316,11 @@ instance Outputable SpecArg where
ppr (SpecDict d) = text "SpecDict" <+> ppr d
ppr UnspecArg = text "UnspecArg"
-specArgFreeVars :: SpecArg -> VarSet
-specArgFreeVars (SpecType ty) = tyCoVarsOfType ty
-specArgFreeVars (SpecDict dx) = exprFreeVars dx
-specArgFreeVars UnspecType = emptyVarSet
-specArgFreeVars UnspecArg = emptyVarSet
+specArgFreeIds :: SpecArg -> IdSet
+specArgFreeIds (SpecType {}) = emptyVarSet
+specArgFreeIds (SpecDict dx) = exprFreeIds dx
+specArgFreeIds UnspecType = emptyVarSet
+specArgFreeIds UnspecArg = emptyVarSet
isSpecDict :: SpecArg -> Bool
isSpecDict (SpecDict {}) = True
@@ -2327,24 +2390,33 @@ specHeader
, [OutBndr] -- Binders for $sf
, [DictBind] -- Auxiliary dictionary bindings
, [OutExpr] -- Specialised arguments for unfolding
- -- Same length as "args for LHS of rule"
+ -- Same length as "Args for LHS of rule"
)
-- We want to specialise on type 'T1', and so we must construct a substitution
-- 'a->T1', as well as a LHS argument for the resulting RULE and unfolding
-- details.
-specHeader env (bndr : bndrs) (SpecType t : args)
- = do { let env' = extendTvSubstList env [(bndr, t)]
- ; (useful, env'', leftover_bndrs, rule_bs, rule_es, bs', dx, spec_args)
- <- specHeader env' bndrs args
+specHeader env (bndr : bndrs) (SpecType ty : args)
+ = do { -- Find qvars, the type variables to add to the binders for the rule
+ -- Namely those free in `ty` that aren't in scope
+ -- See (MP2) in Note [Specialising polymorphic dictionaries]
+ let in_scope = Core.getSubstInScope (se_subst env)
+ qvars = scopedSort $
+ filterOut (`elemInScopeSet` in_scope) $
+ tyCoVarsOfTypeList ty
+ (env1, qvars') = substBndrs env qvars
+ ty' = substTy env1 ty
+ env2 = extendTvSubst env1 bndr ty'
+ ; (useful, env3, leftover_bndrs, rule_bs, rule_es, bs', dx, spec_args)
+ <- specHeader env2 bndrs args
; pure ( useful
- , env''
+ , env3
, leftover_bndrs
- , rule_bs
- , Type t : rule_es
- , bs'
+ , qvars' ++ rule_bs
+ , Type ty' : rule_es
+ , qvars' ++ bs'
, dx
- , Type t : spec_args
+ , Type ty' : spec_args
)
}
@@ -2371,6 +2443,7 @@ specHeader env (bndr : bndrs) (UnspecType : args)
-- a wildcard binder to match the dictionary (See Note [Specialising Calls] for
-- the nitty-gritty), as a LHS rule and unfolding details.
specHeader env (bndr : bndrs) (SpecDict d : args)
+ | not (isDeadBinder bndr)
= do { (env1, bndr') <- newDictBndr env bndr -- See Note [Zap occ info in rule binders]
; let (env2, dx_bind, spec_dict) = bindAuxiliaryDict env1 bndr bndr' d
; (_, env3, leftover_bndrs, rule_bs, rule_es, bs', dx, spec_args)
@@ -2387,29 +2460,44 @@ specHeader env (bndr : bndrs) (SpecDict d : args)
)
}
--- Finally, we have the unspecialised argument 'i'. We need to produce
--- a binder, LHS and RHS argument for the RULE, and a binder for the
--- specialised body.
+-- Finally, we don't want to specialise on this argument 'i':
+-- - It's an UnSpecArg, or
+-- - It's a dead dictionary
+-- We need to produce a binder, LHS and RHS argument for the RULE, and
+-- a binder for the specialised body.
--
-- NB: Calls to 'specHeader' will trim off any trailing 'UnspecArg's, which is
-- why 'i' doesn't appear in our RULE above. But we have no guarantee that
-- there aren't 'UnspecArg's which come /before/ all of the dictionaries, so
-- this case must be here.
-specHeader env (bndr : bndrs) (UnspecArg : args)
+specHeader env (bndr : bndrs) (_ : args)
+ -- The "_" can be UnSpecArg, or SpecDict where the bndr is dead
= do { -- see Note [Zap occ info in rule binders]
let (env', bndr') = substBndr env (zapIdOccInfo bndr)
; (useful, env'', leftover_bndrs, rule_bs, rule_es, bs', dx, spec_args)
<- specHeader env' bndrs args
+
+ ; let bndr_ty = idType bndr'
+
+ -- See Note [Drop dead args from specialisations]
+ -- C.f. GHC.Core.Opt.WorkWrap.Utils.mk_absent_let
+ (mb_spec_bndr, spec_arg)
+ | isDeadBinder bndr
+ , Just lit_expr <- mkLitRubbish bndr_ty
+ = (Nothing, lit_expr)
+ | otherwise
+ = (Just bndr', varToCoreExpr bndr')
+
; pure ( useful
, env''
, leftover_bndrs
, bndr' : rule_bs
, varToCoreExpr bndr' : rule_es
- , if isDeadBinder bndr
- then bs' -- see Note [Drop dead args from specialisations]
- else bndr' : bs'
+ , case mb_spec_bndr of
+ Just b' -> b' : bs'
+ Nothing -> bs'
, dx
- , varToCoreExpr bndr' : spec_args
+ , spec_arg : spec_args
)
}
@@ -2535,6 +2623,88 @@ successfully specialise 'f'.
So the DictBinds in (ud_binds :: OrdList DictBind) may contain
non-dictionary bindings too.
+
+Note [Specialising polymorphic dictionaries]
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+Consider
+ class M a where { foo :: a -> Int }
+
+ instance M (ST s) where ...
+ -- dMST :: forall s. M (ST s)
+
+ wimwam :: forall a. M a => a -> Int
+ wimwam = /\a \(d::M a). body
+
+ f :: ST s -> Int
+ f = /\s \(x::ST s). wimwam @(ST s) (dMST @s) dx + 1
+
+We'd like to specialise wimwam at (ST s), thus
+ $swimwam :: forall s. ST s -> Int
+ $swimwam = /\s. body[ST s/a, (dMST @s)/d]
+
+ RULE forall s (d :: M (ST s)).
+ wimwam @(ST s) d = $swimwam @s
+
+Here are the moving parts:
+
+(MP1) We must /not/ dump the CallInfo
+ CIS wimwam (CI { ci_key = [@(ST s), dMST @s]
+ , ci_fvs = {dMST} })
+ when we come to the /\s. Instead, we simply let it continue to float
+ upwards. Hence ci_fvs is an IdSet, listing the /Ids/ that
+ are free in the call, but not the /TyVars/. Hence using specArgFreeIds
+ in singleCall.
+
+ NB to be fully kosher we should explicitly quantifying the CallInfo
+ over 's', but we don't bother. This would matter if there was an
+ enclosing binding of the same 's', which I don't expect to happen.
+
+(MP2) When we come to specialise the call, we must remember to quantify
+ over 's'. That is done in the SpecType case of specHeader, where
+ we add 's' (called qvars) to the binders of the RULE and the specialised
+ function.
+
+(MP3) If we have f :: forall m. Monoid m => blah, and two calls
+ (f @(Endo b) (d :: Monoid (Endo b))
+ (f @(Endo (c->c)) (d :: Monoid (Endo (c->c)))
+ we want to generate a specialisation only for the first. The second
+ is just a substitution instance of the first, with no greater specialisation.
+ Hence the call to `remove_dups` in `filterCalls`.
+
+All this arose in #13873, in the unexpected form that a SPECIALISE
+pragma made the program slower! The reason was that the specialised
+function $sinsertWith arising from the pragma looked rather like `f`
+above, and failed to specialise a call in its body like wimwam.
+Without the pragma, the original call to `insertWith` was completely
+monomorpic, and specialised in one go.
+
+Wrinkles.
+
+* With -XOverlappingInstances you might worry about this:
+ class C a where ...
+ instance C (Maybe Int) where ... -- $df1 :: C (Maybe Int)
+ instance C (Maybe a) where ... -- $df2 :: forall a. C (Maybe a)
+
+ f :: C a => blah
+ f = rhs
+
+ g = /\a. ...(f @(Maybe a) ($df2 a))...
+ h = ...f @(Maybe Int) $df1
+
+ There are two calls to f, but with different evidence. This patch will
+ combine them into one. But it's OK: this code will never arise unless you
+ use -XIncoherentInstances. Even with -XOverlappingInstances, GHC tries hard
+ to keep dictionaries as singleton types. But that goes out of the window
+ with -XIncoherentInstances -- and that is true even with ordianry type-class
+ specialisation (at least if any inlining has taken place).
+
+ GHC makes very few guarantees when you use -XIncoherentInstances, and its
+ not worth crippling the normal case for the incoherent corner. (The best
+ thing might be to switch off specialisation altogether if incoherence is
+ involved... but incoherence is a property of an instance, not a class, so
+ it's a hard test to make.)
+
+ But see Note [Specialisation and overlapping instances].
-}
instance Outputable DictBind where
@@ -2573,8 +2743,9 @@ data CallInfoSet = CIS Id (Bag CallInfo)
data CallInfo
= CI { ci_key :: [SpecArg] -- All arguments
, ci_fvs :: IdSet -- Free Ids of the ci_key call
- -- _not_ including the main id itself, of course
+ -- /not/ including the main id itself, of course
-- NB: excluding tyvars:
+ -- See Note [Specialising polymorphic dictionaries]
}
type DictExpr = CoreExpr
@@ -2620,17 +2791,12 @@ singleCall :: Id -> [SpecArg] -> UsageDetails
singleCall id args
= MkUD {ud_binds = emptyFDBs,
ud_calls = unitDVarEnv id $ CIS id $
- unitBag (CI { ci_key = args -- used to be tys
+ unitBag (CI { ci_key = args
, ci_fvs = call_fvs }) }
where
- call_fvs = foldr (unionVarSet . specArgFreeVars) emptyVarSet args
- -- The type args (tys) are guaranteed to be part of the dictionary
- -- types, because they are just the constrained types,
- -- and the dictionary is therefore sure to be bound
- -- inside the binding for any type variables free in the type;
- -- hence it's safe to neglect tyvars free in tys when making
- -- the free-var set for this call
- -- BUT I don't trust this reasoning; play safe and include tys_fvs
+ call_fvs = foldr (unionVarSet . specArgFreeIds) emptyVarSet args
+ -- specArgFreeIds: we specifically look for free Ids, not TyVars
+ -- see (MP1) in Note [Specialising polymorphic dictionaries]
--
-- We don't include the 'id' itself.
@@ -2953,15 +3119,15 @@ callsForMe fn uds at MkUD { ud_binds = orig_dbs, ud_calls = orig_calls }
----------------------
filterCalls :: CallInfoSet -> FloatedDictBinds -> [CallInfo]
--- Remove dominated calls
+-- Remove dominated calls (Note [Specialising polymorphic dictionaries])
-- and loopy DFuns (Note [Avoiding loops (DFuns)])
filterCalls (CIS fn call_bag) (FDB { fdb_binds = dbs })
| isDFunId fn -- Note [Avoiding loops (DFuns)] applies only to DFuns
- = filter ok_call unfiltered_calls
+ = filter ok_call de_dupd_calls
| otherwise -- Do not apply it to non-DFuns
- = unfiltered_calls -- See Note [Avoiding loops (non-DFuns)]
+ = de_dupd_calls -- See Note [Avoiding loops (non-DFuns)]
where
- unfiltered_calls = bagToList call_bag
+ de_dupd_calls = remove_dups call_bag
dump_set = foldl' go (unitVarSet fn) dbs
-- This dump-set could also be computed by splitDictBinds
@@ -2975,6 +3141,31 @@ filterCalls (CIS fn call_bag) (FDB { fdb_binds = dbs })
ok_call (CI { ci_fvs = fvs }) = fvs `disjointVarSet` dump_set
+remove_dups :: Bag CallInfo -> [CallInfo]
+-- Calls involving more generic instances beat more specific ones.
+-- See (MP3) in Note [Specialising polymorphic dictionaries]
+remove_dups calls = foldr add [] calls
+ where
+ add :: CallInfo -> [CallInfo] -> [CallInfo]
+ add ci [] = [ci]
+ add ci1 (ci2:cis) | ci2 `beats_or_same` ci1 = ci2:cis
+ | ci1 `beats_or_same` ci2 = ci1:cis
+ | otherwise = ci2 : add ci1 cis
+
+beats_or_same :: CallInfo -> CallInfo -> Bool
+beats_or_same (CI { ci_key = args1 }) (CI { ci_key = args2 })
+ = go args1 args2
+ where
+ go [] _ = True
+ go (arg1:args1) (arg2:args2) = go_arg arg1 arg2 && go args1 args2
+ go (_:_) [] = False
+
+ go_arg (SpecType ty1) (SpecType ty2) = isJust (tcMatchTy ty1 ty2)
+ go_arg UnspecType UnspecType = True
+ go_arg (SpecDict {}) (SpecDict {}) = True
+ go_arg UnspecArg UnspecArg = True
+ go_arg _ _ = False
+
----------------------
splitDictBinds :: FloatedDictBinds -> IdSet -> (FloatedDictBinds, OrdList DictBind, IdSet)
-- splitDictBinds dbs bndrs returns
@@ -3005,15 +3196,18 @@ splitDictBinds (FDB { fdb_binds = dbs, fdb_bndrs = bs }) bndr_set
----------------------
deleteCallsMentioning :: VarSet -> CallDetails -> CallDetails
--- Remove calls *mentioning* bs in any way
-deleteCallsMentioning bs calls
+-- Remove calls mentioning any Id in bndrs
+-- NB: The call is allowed to mention TyVars in bndrs
+-- Note [Specialising polymorphic dictionaries]
+-- ci_fvs are just the free /Ids/
+deleteCallsMentioning bndrs calls
= mapDVarEnv (ciSetFilter keep_call) calls
where
- keep_call (CI { ci_fvs = fvs }) = fvs `disjointVarSet` bs
+ keep_call (CI { ci_fvs = fvs }) = fvs `disjointVarSet` bndrs
deleteCallsFor :: [Id] -> CallDetails -> CallDetails
--- Remove calls *for* bs
-deleteCallsFor bs calls = delDVarEnvList calls bs
+-- Remove calls *for* bndrs
+deleteCallsFor bndrs calls = delDVarEnvList calls bndrs
{-
************************************************************************
@@ -3036,9 +3230,9 @@ mapAndCombineSM f (x:xs) = do (y, uds1) <- f x
(ys, uds2) <- mapAndCombineSM f xs
return (y:ys, uds1 `thenUDs` uds2)
-extendTvSubstList :: SpecEnv -> [(TyVar,Type)] -> SpecEnv
-extendTvSubstList env tv_binds
- = env { se_subst = Core.extendTvSubstList (se_subst env) tv_binds }
+extendTvSubst :: SpecEnv -> TyVar -> Type -> SpecEnv
+extendTvSubst env tv ty
+ = env { se_subst = Core.extendTvSubst (se_subst env) tv ty }
extendInScope :: SpecEnv -> OutId -> SpecEnv
extendInScope env@(SE { se_subst = subst }) bndr
=====================================
compiler/GHC/Core/Subst.hs
=====================================
@@ -26,7 +26,8 @@ module GHC.Core.Subst (
extendIdSubstWithClone,
extendSubst, extendSubstList, extendSubstWithVar,
extendSubstInScope, extendSubstInScopeList, extendSubstInScopeSet,
- isInScope, setInScope, extendTvSubst, extendCvSubst,
+ isInScope, setInScope, getSubstInScope,
+ extendTvSubst, extendCvSubst,
delBndr, delBndrs, zapSubst,
-- ** Substituting and cloning binders
@@ -41,7 +42,6 @@ import GHC.Core
import GHC.Core.FVs
import GHC.Core.Seq
import GHC.Core.Utils
-import GHC.Core.TyCo.Subst ( substCo )
-- We are defining local versions
import GHC.Core.Type hiding ( substTy )
=====================================
compiler/GHC/Core/Type.hs
=====================================
@@ -219,7 +219,7 @@ module GHC.Core.Type (
substTyAddInScope,
substTyUnchecked, substTysUnchecked, substScaledTyUnchecked, substScaledTysUnchecked,
substThetaUnchecked, substTyWithUnchecked,
- substCoUnchecked, substCoWithUnchecked,
+ substCo, substCoUnchecked, substCoWithUnchecked,
substTyVarBndr, substTyVarBndrs, substTyVar, substTyVars,
substVarBndr, substVarBndrs,
substTyCoBndr,
=====================================
testsuite/tests/linters/notes.stdout
=====================================
@@ -2,7 +2,6 @@ ref compiler/GHC/Core/Coercion/Axiom.hs:461:2: Note [RoughMap and rm_empt
ref compiler/GHC/Core/Opt/OccurAnal.hs:857:15: Note [Loop breaking]
ref compiler/GHC/Core/Opt/SetLevels.hs:1580:30: Note [Top level scope]
ref compiler/GHC/Core/Opt/Simplify/Iteration.hs:2675:13: Note [Case binder next]
-ref compiler/GHC/Core/Opt/Simplify/Iteration.hs:3303:0: Note [Suppressing binder-swaps on linear case]
ref compiler/GHC/Core/Opt/Simplify/Iteration.hs:3854:8: Note [Lambda-bound unfoldings]
ref compiler/GHC/Core/Opt/Simplify/Utils.hs:1257:37: Note [Gentle mode]
ref compiler/GHC/Core/Opt/Specialise.hs:1623:28: Note [Arity decrease]
=====================================
testsuite/tests/numeric/should_compile/T19641.stderr
=====================================
@@ -3,30 +3,30 @@
Result size of Tidy Core
= {terms: 22, types: 20, coercions: 0, joins: 0/0}
-integer_to_int
+natural_to_word
= \ eta ->
case eta of {
- IS ipv -> Just (I# ipv);
- IP x1 -> Nothing;
- IN ds -> Nothing
+ NS x1 -> Just (W# x1);
+ NB ds -> Nothing
}
-natural_to_word
+integer_to_int
= \ eta ->
case eta of {
- NS x1 -> Just (W# x1);
- NB ds -> Nothing
+ IS ipv -> Just (I# ipv);
+ IP x1 -> Nothing;
+ IN ds -> Nothing
}
------ Local rules for imported ids --------
-"SPEC/Test toIntegralSized @Natural @Word"
- forall $dIntegral $dIntegral1 $dBits $dBits1.
- toIntegralSized $dIntegral $dIntegral1 $dBits $dBits1
- = natural_to_word
"SPEC/Test toIntegralSized @Integer @Int"
forall $dIntegral $dIntegral1 $dBits $dBits1.
toIntegralSized $dIntegral $dIntegral1 $dBits $dBits1
= integer_to_int
+"SPEC/Test toIntegralSized @Natural @Word"
+ forall $dIntegral $dIntegral1 $dBits $dBits1.
+ toIntegralSized $dIntegral $dIntegral1 $dBits $dBits1
+ = natural_to_word
=====================================
testsuite/tests/simplCore/should_compile/T8331.stderr
=====================================
@@ -1,5 +1,149 @@
==================== Tidy Core rules ====================
+"SPEC $c*> @(ST s) @_"
+ forall (@s) (@r) ($dApplicative :: Applicative (ST s)).
+ $fApplicativeReaderT_$c*> @(ST s) @r $dApplicative
+ = ($fApplicativeReaderT2 @s @r)
+ `cast` (forall (a :: <*>_N) (b :: <*>_N).
+ <ReaderT r (ST s) a>_R
+ %<'Many>_N ->_R <ReaderT r (ST s) b>_R
+ %<'Many>_N ->_R <r>_R %<'Many>_N ->_R Sym (N:ST[0] <s>_N <b>_R)
+ ; Sym (N:ReaderT[0] <*>_N <r>_R <ST s>_R <b>_N)
+ :: Coercible
+ (forall {a} {b}.
+ ReaderT r (ST s) a -> ReaderT r (ST s) b -> r -> STRep s b)
+ (forall {a} {b}.
+ ReaderT r (ST s) a -> ReaderT r (ST s) b -> ReaderT r (ST s) b))
+"SPEC $c<$ @(ST s) @_"
+ forall (@s) (@r) ($dFunctor :: Functor (ST s)).
+ $fFunctorReaderT_$c<$ @(ST s) @r $dFunctor
+ = ($fApplicativeReaderT6 @s @r)
+ `cast` (forall (a :: <*>_N) (b :: <*>_N).
+ <a>_R
+ %<'Many>_N ->_R <ReaderT r (ST s) b>_R
+ %<'Many>_N ->_R <r>_R %<'Many>_N ->_R Sym (N:ST[0] <s>_N <a>_R)
+ ; Sym (N:ReaderT[0] <*>_N <r>_R <ST s>_R <a>_N)
+ :: Coercible
+ (forall {a} {b}. a -> ReaderT r (ST s) b -> r -> STRep s a)
+ (forall {a} {b}. a -> ReaderT r (ST s) b -> ReaderT r (ST s) a))
+"SPEC $c<* @(ST s) @_"
+ forall (@s) (@r) ($dApplicative :: Applicative (ST s)).
+ $fApplicativeReaderT_$c<* @(ST s) @r $dApplicative
+ = ($fApplicativeReaderT1 @s @r)
+ `cast` (forall (a :: <*>_N) (b :: <*>_N).
+ <ReaderT r (ST s) a>_R
+ %<'Many>_N ->_R <ReaderT r (ST s) b>_R
+ %<'Many>_N ->_R <r>_R %<'Many>_N ->_R Sym (N:ST[0] <s>_N <a>_R)
+ ; Sym (N:ReaderT[0] <*>_N <r>_R <ST s>_R <a>_N)
+ :: Coercible
+ (forall {a} {b}.
+ ReaderT r (ST s) a -> ReaderT r (ST s) b -> r -> STRep s a)
+ (forall {a} {b}.
+ ReaderT r (ST s) a -> ReaderT r (ST s) b -> ReaderT r (ST s) a))
+"SPEC $c<*> @(ST s) @_"
+ forall (@s) (@r) ($dApplicative :: Applicative (ST s)).
+ $fApplicativeReaderT9 @(ST s) @r $dApplicative
+ = ($fApplicativeReaderT4 @s @r)
+ `cast` (forall (a :: <*>_N) (b :: <*>_N).
+ <ReaderT r (ST s) (a -> b)>_R
+ %<'Many>_N ->_R <ReaderT r (ST s) a>_R
+ %<'Many>_N ->_R <r>_R
+ %<'Many>_N ->_R Sym (N:ST[0] <s>_N <b>_R)
+ :: Coercible
+ (forall {a} {b}.
+ ReaderT r (ST s) (a -> b) -> ReaderT r (ST s) a -> r -> STRep s b)
+ (forall {a} {b}.
+ ReaderT r (ST s) (a -> b) -> ReaderT r (ST s) a -> r -> ST s b))
+"SPEC $c>> @(ST s) @_"
+ forall (@s) (@r) ($dMonad :: Monad (ST s)).
+ $fMonadReaderT1 @(ST s) @r $dMonad
+ = $fMonadAbstractIOSTReaderT_$s$c>> @s @r
+"SPEC $c>>= @(ST s) @_"
+ forall (@s) (@r) ($dMonad :: Monad (ST s)).
+ $fMonadReaderT2 @(ST s) @r $dMonad
+ = ($fMonadAbstractIOSTReaderT2 @s @r)
+ `cast` (forall (a :: <*>_N) (b :: <*>_N).
+ <ReaderT r (ST s) a>_R
+ %<'Many>_N ->_R <a -> ReaderT r (ST s) b>_R
+ %<'Many>_N ->_R <r>_R
+ %<'Many>_N ->_R Sym (N:ST[0] <s>_N <b>_R)
+ :: Coercible
+ (forall {a} {b}.
+ ReaderT r (ST s) a -> (a -> ReaderT r (ST s) b) -> r -> STRep s b)
+ (forall {a} {b}.
+ ReaderT r (ST s) a -> (a -> ReaderT r (ST s) b) -> r -> ST s b))
+"SPEC $cfmap @(ST s) @_"
+ forall (@s) (@r) ($dFunctor :: Functor (ST s)).
+ $fFunctorReaderT_$cfmap @(ST s) @r $dFunctor
+ = ($fApplicativeReaderT7 @s @r)
+ `cast` (forall (a :: <*>_N) (b :: <*>_N).
+ <a -> b>_R
+ %<'Many>_N ->_R <ReaderT r (ST s) a>_R
+ %<'Many>_N ->_R <r>_R %<'Many>_N ->_R Sym (N:ST[0] <s>_N <b>_R)
+ ; Sym (N:ReaderT[0] <*>_N <r>_R <ST s>_R <b>_N)
+ :: Coercible
+ (forall {a} {b}. (a -> b) -> ReaderT r (ST s) a -> r -> STRep s b)
+ (forall {a} {b}.
+ (a -> b) -> ReaderT r (ST s) a -> ReaderT r (ST s) b))
+"SPEC $cliftA2 @(ST s) @_"
+ forall (@s) (@r) ($dApplicative :: Applicative (ST s)).
+ $fApplicativeReaderT_$cliftA2 @(ST s) @r $dApplicative
+ = ($fApplicativeReaderT3 @s @r)
+ `cast` (forall (a :: <*>_N) (b :: <*>_N) (c :: <*>_N).
+ <a -> b -> c>_R
+ %<'Many>_N ->_R <ReaderT r (ST s) a>_R
+ %<'Many>_N ->_R <ReaderT r (ST s) b>_R
+ %<'Many>_N ->_R <r>_R %<'Many>_N ->_R Sym (N:ST[0] <s>_N <c>_R)
+ ; Sym (N:ReaderT[0] <*>_N <r>_R <ST s>_R <c>_N)
+ :: Coercible
+ (forall {a} {b} {c}.
+ (a -> b -> c)
+ -> ReaderT r (ST s) a -> ReaderT r (ST s) b -> r -> STRep s c)
+ (forall {a} {b} {c}.
+ (a -> b -> c)
+ -> ReaderT r (ST s) a -> ReaderT r (ST s) b -> ReaderT r (ST s) c))
+"SPEC $cp1Applicative @(ST s) @_"
+ forall (@s) (@r) ($dApplicative :: Applicative (ST s)).
+ $fApplicativeReaderT_$cp1Applicative @(ST s) @r $dApplicative
+ = $fApplicativeReaderT_$s$fFunctorReaderT @s @r
+"SPEC $cp1Monad @(ST s) @_"
+ forall (@s) (@r) ($dMonad :: Monad (ST s)).
+ $fMonadReaderT_$cp1Monad @(ST s) @r $dMonad
+ = $fApplicativeReaderT_$s$fApplicativeReaderT @s @r
+"SPEC $cpure @(ST s) @_"
+ forall (@s) (@r) ($dApplicative :: Applicative (ST s)).
+ $fApplicativeReaderT_$cpure @(ST s) @r $dApplicative
+ = ($fApplicativeReaderT5 @s @r)
+ `cast` (forall (a :: <*>_N).
+ <a>_R
+ %<'Many>_N ->_R <r>_R %<'Many>_N ->_R Sym (N:ST[0] <s>_N <a>_R)
+ ; Sym (N:ReaderT[0] <*>_N <r>_R <ST s>_R <a>_N)
+ :: Coercible
+ (forall {a}. a -> r -> STRep s a)
+ (forall {a}. a -> ReaderT r (ST s) a))
+"SPEC $creturn @(ST s) @_"
+ forall (@s) (@r) ($dMonad :: Monad (ST s)).
+ $fMonadReaderT_$creturn @(ST s) @r $dMonad
+ = ($fApplicativeReaderT5 @s @r)
+ `cast` (forall (a :: <*>_N).
+ <a>_R
+ %<'Many>_N ->_R <r>_R %<'Many>_N ->_R Sym (N:ST[0] <s>_N <a>_R)
+ ; Sym (N:ReaderT[0] <*>_N <r>_R <ST s>_R <a>_N)
+ :: Coercible
+ (forall {a}. a -> r -> STRep s a)
+ (forall {a}. a -> ReaderT r (ST s) a))
+"SPEC $fApplicativeReaderT @(ST s) @_"
+ forall (@s) (@r) ($dApplicative :: Applicative (ST s)).
+ $fApplicativeReaderT @(ST s) @r $dApplicative
+ = $fApplicativeReaderT_$s$fApplicativeReaderT @s @r
+"SPEC $fFunctorReaderT @(ST s) @_"
+ forall (@s) (@r) ($dFunctor :: Functor (ST s)).
+ $fFunctorReaderT @(ST s) @r $dFunctor
+ = $fApplicativeReaderT_$s$fFunctorReaderT @s @r
+"SPEC $fMonadReaderT @(ST s) @_"
+ forall (@s) (@r) ($dMonad :: Monad (ST s)).
+ $fMonadReaderT @(ST s) @r $dMonad
+ = $fMonadAbstractIOSTReaderT_$s$fMonadReaderT @s @r
"USPEC useAbstractMonad @(ReaderT Int (ST s))"
forall (@s)
($dMonadAbstractIOST :: MonadAbstractIOST (ReaderT Int (ST s))).
=====================================
testsuite/tests/simplCore/should_compile/all.T
=====================================
@@ -359,7 +359,6 @@ test('T19586', normal, compile, [''])
test('T19599', normal, compile, ['-O -ddump-rules'])
test('T19599a', normal, compile, ['-O -ddump-rules'])
-test('T13873', [expect_broken(21229), grep_errmsg(r'SPEC') ], compile, ['-O -ddump-rules'])
# Look for a specialisation rule for wimwam
test('T19672', normal, compile, ['-O2 -ddump-rules'])
@@ -435,3 +434,6 @@ test('T21148', [grep_errmsg(r'Cpr=') ], compile, ['-O -ddump-simpl'])
test('T21851', [grep_errmsg(r'case.*w\$sf') ], multimod_compile, ['T21851', '-O -dno-typeable-binds -dsuppress-uniques'])
# One module, T22097.hs, has OPTIONS_GHC -ddump-simpl
test('T22097', [grep_errmsg(r'case.*wgoEven') ], multimod_compile, ['T22097', '-O -dno-typeable-binds -dsuppress-uniques'])
+
+test('T13873', [ grep_errmsg(r'SPEC') ], compile, ['-O -ddump-rules'])
+
View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/8d2dbe2db4cc7c8b6d39b1ea64b0508304a3273c...5a997e16cb2079c52f980d59af3de176922fa320
--
View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/8d2dbe2db4cc7c8b6d39b1ea64b0508304a3273c...5a997e16cb2079c52f980d59af3de176922fa320
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