Asyncify: spill reference-typed locals to tables

src/ir/type-updating.cpp

@@ -498,11 +498,22 @@ Type GlobalTypeRewriter::getTempTupleType(Tuple tuple) {
 
 namespace TypeUpdating {
 
-void handleNonDefaultableLocals(Function* func, Module& wasm) {
+void handleNonDefaultableLocals(Function* func,
+                                Module& wasm,
+                                const std::unordered_set<Index>* forced) {
   if (!wasm.features.hasReferenceTypes()) {
     // No references, so no non-nullable ones at all.
     return;
   }
+  std::unordered_set<Index> badIndexes;
+  if (forced) {
+    for (auto index : *forced) {
+      assert(!func->isParam(index));
+      if (!func->getLocalType(index).isDefaultable()) {
+        badIndexes.insert(index);
+      }
+    }
+  }
   bool hasNonNullable = false;
   for (auto varType : func->vars) {
     for (auto type : varType) {
@@ -522,7 +533,6 @@ void handleNonDefaultableLocals(Function* func, Module& wasm) {
   // the wasm spec. We do not need to modify such locals.
   LocalStructuralDominance info(
     func, wasm, LocalStructuralDominance::NonNullableOnly);
-  std::unordered_set<Index> badIndexes;
   for (auto index : info.nonDominatingIndices) {
     badIndexes.insert(index);
 

src/ir/type-updating.h

@@ -17,6 +17,8 @@
 #ifndef wasm_ir_type_updating_h
 #define wasm_ir_type_updating_h
 
+#include <unordered_set>
+
 #include "ir/branch-utils.h"
 #include "ir/module-utils.h"
 #include "support/insert_ordered.h"
@@ -564,7 +566,13 @@ namespace TypeUpdating {
 // them. Atm this turns them into nullable ones, and adds ref.as_non_null on
 // their uses (which keeps the type of the users identical).
 // This may also handle other types of nondefaultable locals in the future.
-void handleNonDefaultableLocals(Function* func, Module& wasm);
+//
+// If `forced` is provided, the locals at those indexes are made nullable as
+// well, even if they validate as they are.
+void handleNonDefaultableLocals(
+  Function* func,
+  Module& wasm,
+  const std::unordered_set<Index>* forced = nullptr);
 
 // Returns the type that a local should be, after handling of non-
 // defaultability.