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diff --git a/src/passes/RemoveUnusedFunctions.cpp b/src/passes/RemoveUnusedFunctions.cpp
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+++ b/src/passes/RemoveUnusedFunctions.cpp
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+/*
+ * Copyright 2016 WebAssembly Community Group participants
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+//
+// Removes functions that are never used.
+//
+
+
+#include <memory>
+
+#include "wasm.h"
+#include "pass.h"
+#include "ast_utils.h"
+
+namespace wasm {
+
+struct RemoveUnusedFunctions : public Pass {
+  void run(PassRunner* runner, Module* module) override {
+    std::vector<Function*> root;
+    // Module start is a root.
+    if (module->start.is()) {
+      root.push_back(module->getFunction(module->start));
+    }
+    // Exports are roots.
+    for (auto& curr : module->exports) {
+      root.push_back(module->getFunction(curr->value));
+    }
+    // For now, all functions that can be called indirectly are marked as roots.
+    for (auto& curr : module->table.names) {
+      root.push_back(module->getFunction(curr));
+    }
+    // Compute function reachability starting from the root set.
+    DirectCallGraphAnalyzer analyzer(module, root);
+    // Remove unreachable functions.
+    auto& v = module->functions;
+    v.erase(std::remove_if(v.begin(), v.end(), [&](const std::unique_ptr<Function>& curr) {
+      return analyzer.reachable.count(curr.get()) == 0;
+    }), v.end());
+    assert(module->functions.size() == analyzer.reachable.size());
+  }
+};
+
+static RegisterPass<RemoveUnusedFunctions> registerPass("remove-unused-functions", "removes unused functions");
+
+} // namespace wasm