4 files changed, 16 insertions, 1 deletions
diff --git a/src/ir/ReFinalize.cpp b/src/ir/ReFinalize.cpp
index 59b994ec1..8acffaa34 100644
--- a/src/ir/ReFinalize.cpp
+++ b/src/ir/ReFinalize.cpp
@@ -175,6 +175,7 @@ void ReFinalize::visitRefAs(RefAs* curr) { curr->finalize(); }
 void ReFinalize::visitStringNew(StringNew* curr) { curr->finalize(); }
 void ReFinalize::visitStringConst(StringConst* curr) { curr->finalize(); }
 void ReFinalize::visitStringMeasure(StringMeasure* curr) { curr->finalize(); }
+void ReFinalize::visitStringEncode(StringEncode* curr) { curr->finalize(); }
 
 void ReFinalize::visitFunction(Function* curr) {
   // we may have changed the body from unreachable to none, which might be bad
diff --git a/src/ir/cost.h b/src/ir/cost.h
index 372c597a5..afc091ffb 100644
--- a/src/ir/cost.h
+++ b/src/ir/cost.h
@@ -678,6 +678,9 @@ struct CostAnalyzer : public OverriddenVisitor<CostAnalyzer, CostType> {
   CostType visitStringMeasure(StringMeasure* curr) {
     return 6 + visit(curr->ref);
   }
+  CostType visitStringEncode(StringEncode* curr) {
+    return 6 + visit(curr->ref) + visit(curr->ptr);
+  }
 
 private:
   CostType nullCheckCost(Expression* ref) {
diff --git a/src/ir/effects.h b/src/ir/effects.h
index b8007cfba..8e33f65bf 100644
--- a/src/ir/effects.h
+++ b/src/ir/effects.h
@@ -734,7 +734,14 @@ private:
     }
     void visitStringNew(StringNew* curr) {}
     void visitStringConst(StringConst* curr) {}
-    void visitStringMeasure(StringMeasure* curr) {}
+    void visitStringMeasure(StringMeasure* curr) {
+      // traps when ref is null.
+      parent.implicitTrap = true;
+    }
+    void visitStringEncode(StringEncode* curr) {
+      // traps when ref is null or we write out of bounds.
+      parent.implicitTrap = true;
+    }
   };
 
 public:
diff --git a/src/ir/possible-contents.cpp b/src/ir/possible-contents.cpp
index 3b5c19f15..c865585f1 100644
--- a/src/ir/possible-contents.cpp
+++ b/src/ir/possible-contents.cpp
@@ -685,6 +685,10 @@ struct InfoCollector
     // TODO: optimize when possible
     addRoot(curr);
   }
+  void visitStringEncode(StringEncode* curr) {
+    // TODO: optimize when possible
+    addRoot(curr);
+  }
 
   // TODO: Model which throws can go to which catches. For now, anything thrown
   //       is sent to the location of that tag, and any catch of that tag can