I seem to relearn blr != return once every month or so.

src/alloy/hir/hir_builder.h

@@ -81,6 +81,7 @@ public:
   void CallExtern(runtime::FunctionInfo* symbol_info);
   void Return();
   void ReturnTrue(Value* cond);
+  void SetReturnAddress(Value* value);
 
   void Branch(Label* label, uint32_t branch_flags = 0);
   void Branch(Block* block, uint32_t branch_flags = 0);