7 files changed, 40 insertions, 0 deletions
diff --git a/src/ir/ReFinalize.cpp b/src/ir/ReFinalize.cpp
index 65f5c4724..0338f630c 100644
--- a/src/ir/ReFinalize.cpp
+++ b/src/ir/ReFinalize.cpp
@@ -182,6 +182,8 @@ void ReFinalize::visitStringSliceIter(StringSliceIter* curr) {
   curr->finalize();
 }
 
+void ReFinalize::visitResume(Resume* curr) { curr->finalize(); }
+
 void ReFinalize::visitExport(Export* curr) { WASM_UNREACHABLE("unimp"); }
 void ReFinalize::visitGlobal(Global* curr) { WASM_UNREACHABLE("unimp"); }
 void ReFinalize::visitTable(Table* curr) { WASM_UNREACHABLE("unimp"); }
diff --git a/src/ir/branch-utils.h b/src/ir/branch-utils.h
index 3c0275701..28e29ede4 100644
--- a/src/ir/branch-utils.h
+++ b/src/ir/branch-utils.h
@@ -82,6 +82,13 @@ void operateOnScopeNameUsesAndSentTypes(Expression* expr, T func) {
           func(name, tt->sentTypes[i]);
         }
       }
+    } else if (auto* r = expr->dynCast<Resume>()) {
+      for (Index i = 0; i < r->handlerTags.size(); i++) {
+        auto dest = r->handlerTags[i];
+        if (dest == name) {
+          func(name, r->sentTypes[i]);
+        }
+      }
     } else {
       assert(expr->is<Try>() || expr->is<Rethrow>()); // delegate or rethrow
     }
@@ -106,6 +113,10 @@ void operateOnScopeNameUsesAndSentValues(Expression* expr, T func) {
       // The values are supplied by throwing instructions, so we are unable to
       // know what they will be here.
       func(name, nullptr);
+    } else if (auto* res = expr->dynCast<Resume>()) {
+      // The values are supplied by suspend instructions executed while running
+      // the continuation, so we are unable to know what they will be here.
+      func(name, nullptr);
     } else {
       assert(expr->is<Try>() || expr->is<Rethrow>()); // delegate or rethrow
     }
diff --git a/src/ir/cost.h b/src/ir/cost.h
index 0e87317a6..821e46524 100644
--- a/src/ir/cost.h
+++ b/src/ir/cost.h
@@ -726,6 +726,11 @@ struct CostAnalyzer : public OverriddenVisitor<CostAnalyzer, CostType> {
     return 8 + visit(curr->ref) + visit(curr->num);
   }
 
+  CostType visitResume(Resume* curr) {
+    // Inspired by indirect calls, but twice the cost.
+    return 12 + visit(curr->cont);
+  }
+
 private:
   CostType nullCheckCost(Expression* ref) {
     // A nullable type requires a bounds check in most VMs.
diff --git a/src/ir/effects.h b/src/ir/effects.h
index 1156cd823..3ff320a88 100644
--- a/src/ir/effects.h
+++ b/src/ir/effects.h
@@ -973,6 +973,19 @@ private:
       // traps when ref is null.
       parent.implicitTrap = true;
     }
+
+    void visitResume(Resume* curr) {
+      // This acts as a kitchen sink effect.
+      parent.calls = true;
+
+      // resume instructions accept nullable continuation references and trap
+      // on null.
+      parent.implicitTrap = true;
+
+      if (parent.features.hasExceptionHandling() && parent.tryDepth == 0) {
+        parent.throws_ = true;
+      }
+    }
   };
 
 public:
diff --git a/src/ir/module-utils.cpp b/src/ir/module-utils.cpp
index afe4a4c54..304ddb04d 100644
--- a/src/ir/module-utils.cpp
+++ b/src/ir/module-utils.cpp
@@ -341,6 +341,8 @@ struct CodeScanner
       counts.include(get->type);
     } else if (auto* set = curr->dynCast<ArraySet>()) {
       counts.note(set->ref->type);
+    } else if (auto* resume = curr->dynCast<Resume>()) {
+      counts.note(resume->contType);
     } else if (Properties::isControlFlowStructure(curr)) {
       counts.noteControlFlow(Signature(Type::none, curr->type));
     }
diff --git a/src/ir/possible-contents.cpp b/src/ir/possible-contents.cpp
index 67b33553d..2f900f0ed 100644
--- a/src/ir/possible-contents.cpp
+++ b/src/ir/possible-contents.cpp
@@ -1199,6 +1199,11 @@ struct InfoCollector
 
   void visitReturn(Return* curr) { addResult(curr->value); }
 
+  void visitResume(Resume* curr) {
+    // TODO: optimize when possible
+    addRoot(curr);
+  }
+
   void visitFunction(Function* func) {
     // Functions with a result can flow a value out from their body.
     addResult(func->body);
diff --git a/src/ir/subtype-exprs.h b/src/ir/subtype-exprs.h
index 86805f88a..65558b430 100644
--- a/src/ir/subtype-exprs.h
+++ b/src/ir/subtype-exprs.h
@@ -333,6 +333,8 @@ struct SubtypingDiscoverer : public OverriddenVisitor<SubType> {
   void visitStringIterMove(StringIterMove* curr) {}
   void visitStringSliceWTF(StringSliceWTF* curr) {}
   void visitStringSliceIter(StringSliceIter* curr) {}
+
+  void visitResume(Resume* curr) { WASM_UNREACHABLE("not implemented"); }
 };
 
 } // namespace wasm