add RemoveUnusedNames pass

1 files changed, 50 insertions, 0 deletions

diff --git a/src/passes/RemoveUnusedNames.cpp b/src/passes/RemoveUnusedNames.cpp
new file mode 100644
index 000000000..9c0b4a83f
--- /dev/null
+++ b/src/passes/RemoveUnusedNames.cpp
@@ -0,0 +1,50 @@
+/*
+ * Copyright 2015 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 names from locations that are never branched to.
+//
+
+#include <wasm.h>
+#include <pass.h>
+
+namespace wasm {
+
+struct RemoveUnusedNames : public Pass {
+  std::set<Name> used;
+
+  void prepare(PassRunner* runner, Module *module) override {
+    struct Scanner : public WasmWalker {
+      std::set<Name>& used;
+      Scanner(std::set<Name>& used) : used(used) {}
+      void visitBreak(Break *curr) override {
+        used.insert(curr->name);
+      }
+    };
+    Scanner scanner(used);
+    scanner.startWalk(module);
+  }
+
+  void visitBlock(Block *curr) override {
+    if (curr->name.is() && used.count(curr->name) == 0) {
+      curr->name = Name();
+    }
+  }
+};
+
+static RegisterPass<RemoveUnusedNames> registerPass("remove-unused-names", "removes names from locations that are never branched to");
+
+} // namespace wasm