diff options
Diffstat (limited to 'compiler/GHC/Core.hs')
| -rw-r--r-- | compiler/GHC/Core.hs | 21 |
1 files changed, 12 insertions, 9 deletions
diff --git a/compiler/GHC/Core.hs b/compiler/GHC/Core.hs index bc61929ed4..a99a1adfd6 100644 --- a/compiler/GHC/Core.hs +++ b/compiler/GHC/Core.hs @@ -798,15 +798,18 @@ and case-of-case] in GHC.Core.Opt.Simplify): in jump j z w -The body of the join point now returns a Bool, so the label `j` has to have its -type updated accordingly. Inconvenient though this may be, it has the advantage -that 'GHC.Core.Utils.exprType' can still return a type for any expression, including -a jump. - -This differs from the paper (see Note [Invariants on join points]). In the -paper, we instead give j the type `Int -> Bool -> forall a. a`. Then each jump -carries the "return type" as a parameter, exactly the way other non-returning -functions like `error` work: +The body of the join point now returns a Bool, so the label `j` has to +have its type updated accordingly, which is done by +GHC.Core.Opt.Simplify.Env.adjustJoinPointType. Inconvenient though +this may be, it has the advantage that 'GHC.Core.Utils.exprType' can +still return a type for any expression, including a jump. + +Relationship to the paper + +This plan differs from the paper (see Note [Invariants on join +points]). In the paper, we instead give j the type `Int -> Bool -> +forall a. a`. Then each jump carries the "return type" as a parameter, +exactly the way other non-returning functions like `error` work: case (join j :: Int -> Bool -> forall a. a |