diff options
| -rw-r--r-- | compiler/codeGen/StgCmmClosure.hs | 11 | ||||
| -rw-r--r-- | compiler/simplStg/RepType.hs | 4 | ||||
| -rw-r--r-- | compiler/simplStg/UnariseStg.hs | 2 |
3 files changed, 14 insertions, 3 deletions
diff --git a/compiler/codeGen/StgCmmClosure.hs b/compiler/codeGen/StgCmmClosure.hs index 437219bf45..ac8db1268f 100644 --- a/compiler/codeGen/StgCmmClosure.hs +++ b/compiler/codeGen/StgCmmClosure.hs @@ -166,20 +166,27 @@ assertNonVoidStgArgs args = ASSERT(not (any (isVoidTy . stgArgType) args)) -- Why are these here? +-- | Assumes that there is precisely one 'PrimRep' of the type. This assumption +-- holds after unarise. +-- See Note [Post-unarisation invariants] idPrimRep :: Id -> PrimRep idPrimRep id = typePrimRep1 (idType id) - -- NB: typePrimRep1 fails on unboxed tuples, - -- but by StgCmm no Ids have unboxed tuple type -- See also Note [VoidRep] in RepType +-- | Assumes that Ids have one PrimRep, which holds after unarisation. +-- See Note [Post-unarisation invariants] addIdReps :: [NonVoid Id] -> [NonVoid (PrimRep, Id)] addIdReps = map (\id -> let id' = fromNonVoid id in NonVoid (idPrimRep id', id')) +-- | Assumes that arguments have one PrimRep, which holds after unarisation. +-- See Note [Post-unarisation invariants] addArgReps :: [NonVoid StgArg] -> [NonVoid (PrimRep, StgArg)] addArgReps = map (\arg -> let arg' = fromNonVoid arg in NonVoid (argPrimRep arg', arg')) +-- | Assumes that the argument has one PrimRep, which holds after unarisation. +-- See Note [Post-unarisation invariants] argPrimRep :: StgArg -> PrimRep argPrimRep arg = typePrimRep1 (stgArgType arg) diff --git a/compiler/simplStg/RepType.hs b/compiler/simplStg/RepType.hs index f235344848..75fde79d87 100644 --- a/compiler/simplStg/RepType.hs +++ b/compiler/simplStg/RepType.hs @@ -472,7 +472,9 @@ typePrimRep ty = kindPrimRep (text "typePrimRep" <+> (typeKind ty) -- | Like 'typePrimRep', but assumes that there is precisely one 'PrimRep' output; --- an empty list of PrimReps becomes a VoidRep +-- an empty list of PrimReps becomes a VoidRep. +-- This assumption holds after unarise, see Note [Post-unarisation invariants]. +-- Before unarise it may or may not hold. -- See also Note [RuntimeRep and PrimRep] and Note [VoidRep] typePrimRep1 :: HasDebugCallStack => UnaryType -> PrimRep typePrimRep1 ty = case typePrimRep ty of diff --git a/compiler/simplStg/UnariseStg.hs b/compiler/simplStg/UnariseStg.hs index c908580f2f..57e9f3351a 100644 --- a/compiler/simplStg/UnariseStg.hs +++ b/compiler/simplStg/UnariseStg.hs @@ -188,6 +188,8 @@ STG programs after unarisation have these invariants: `StgCmmEnv.NonVoid`, for example. * Alt binders (binders in patterns) are always non-void. + + * Binders always have zero (for void arguments) or one PrimRep. -} {-# LANGUAGE CPP, TupleSections #-} |