From e47dfd352bcf5ba71d18e402364be3e1c0df939f Mon Sep 17 00:00:00 2001 From: Alon Zakai Date: Tue, 27 Jul 2021 08:21:08 -0700 Subject: [Wasm GC] DeadArgumentElimination: Do not refine return types of tail callees (#4025) If there is a tail call, we can't change the return type of the function, as it must match in the functions doing a tail call of it. --- src/passes/DeadArgumentElimination.cpp | 12 +++++++++--- 1 file changed, 9 insertions(+), 3 deletions(-) (limited to 'src') diff --git a/src/passes/DeadArgumentElimination.cpp b/src/passes/DeadArgumentElimination.cpp index ddba3bee8..7ba1be9f8 100644 --- a/src/passes/DeadArgumentElimination.cpp +++ b/src/passes/DeadArgumentElimination.cpp @@ -327,8 +327,14 @@ struct DAE : public Pass { // affect whether an argument is used or not, it just refines the type // where possible. refineArgumentTypes(func, calls, module); - // Refine return types as well. - if (refineReturnTypes(func, calls, module)) { + // Refine return types as well, if we can. We cannot do so if this + // function is tail-called, because then the return type must match that + // of the function doing a tail call of it - we cannot change just one of + // them. + // + // TODO: Try to optimize in a more holistic manner, see the TODO in + // refineReturnTypes() about missing a global optimum. + if (!tailCallees.count(name) && refineReturnTypes(func, calls, module)) { refinedReturnTypes = true; } // Check if all calls pass the same constant for a particular argument. @@ -434,7 +440,7 @@ struct DAE : public Pass { if (infoMap[name].hasTailCalls) { continue; } - if (tailCallees.find(name) != tailCallees.end()) { + if (tailCallees.count(name)) { continue; } auto iter = allCalls.find(name); -- cgit v1.2.3