diff options
Diffstat (limited to 'compiler/GHC/Core/Opt/CallArity.hs')
| -rw-r--r-- | compiler/GHC/Core/Opt/CallArity.hs | 9 |
1 files changed, 4 insertions, 5 deletions
diff --git a/compiler/GHC/Core/Opt/CallArity.hs b/compiler/GHC/Core/Opt/CallArity.hs index 67b9a88875..306b3bd446 100644 --- a/compiler/GHC/Core/Opt/CallArity.hs +++ b/compiler/GHC/Core/Opt/CallArity.hs @@ -17,7 +17,7 @@ import GHC.Types.Var.Env import GHC.Types.Basic import GHC.Core import GHC.Types.Id -import GHC.Core.Opt.Arity ( typeArity, typeOneShots ) +import GHC.Core.Opt.Arity ( typeArity ) import GHC.Core.Utils ( exprIsCheap, exprIsTrivial ) import GHC.Data.Graph.UnVar import GHC.Types.Demand @@ -377,15 +377,14 @@ a body representing “all external calls”, which returns a pessimistic CallArityRes (the co-call graph is the complete graph, all arityies 0). Note [Trimming arity] -~~~~~~~~~~~~~~~~~~~~~~~~~~~~ - +~~~~~~~~~~~~~~~~~~~~~ In the Call Arity papers, we are working on an untyped lambda calculus with no other id annotations, where eta-expansion is always possible. But this is not the case for Core! 1. We need to ensure the invariant callArity e <= typeArity (exprType e) for the same reasons that exprArity needs this invariant (see Note - [exprArity invariant] in GHC.Core.Opt.Arity). + [typeArity invariants] in GHC.Core.Opt.Arity). If we are not doing that, a too-high arity annotation will be stored with the id, confusing the simplifier later on. @@ -544,7 +543,7 @@ callArityAnal arity int (Let bind e) -- Which bindings should we look at? -- See Note [Which variables are interesting] isInteresting :: Var -> Bool -isInteresting v = not $ null $ typeOneShots $ idType v +isInteresting v = typeArity (idType v) > 0 interestingBinds :: CoreBind -> [Var] interestingBinds = filter isInteresting . bindersOf |