3 files changed, 130 insertions, 50 deletions
diff --git a/src/ir/count.h b/src/ir/count.h
deleted file mode 100644
index d9c89b4ce..000000000
--- a/src/ir/count.h
+++ /dev/null
@@ -1,50 +0,0 @@
-/*
- * 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.
- */
-
-#ifndef wasm_ir_count_h
-#define wasm_ir_count_h
-
-namespace wasm {
-
-struct GetLocalCounter : public PostWalker<GetLocalCounter> {
-  std::vector<Index> num;
-
-  GetLocalCounter() = default;
-  GetLocalCounter(Function* func) {
-    analyze(func, func->body);
-  }
-  GetLocalCounter(Function* func, Expression* ast) {
-    analyze(func, ast);
-  }
-
-  void analyze(Function* func) {
-    analyze(func, func->body);
-  }
-  void analyze(Function* func, Expression* ast) {
-    num.resize(func->getNumLocals());
-    std::fill(num.begin(), num.end(), 0);
-    walk(ast);
-  }
-
-  void visitGetLocal(GetLocal *curr) {
-    num[curr->index]++;
-  }
-};
-
-} // namespace wasm
-
-#endif // wasm_ir_count_h
-
diff --git a/src/ir/local-utils.h b/src/ir/local-utils.h
new file mode 100644
index 000000000..2feeeeb00
--- /dev/null
+++ b/src/ir/local-utils.h
@@ -0,0 +1,86 @@
+/*
+ * Copyright 2019 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.
+ */
+
+#ifndef wasm_ir_local_utils_h
+#define wasm_ir_local_utils_h
+
+#include <ir/effects.h>
+
+namespace wasm {
+
+struct GetLocalCounter : public PostWalker<GetLocalCounter> {
+  std::vector<Index> num;
+
+  GetLocalCounter() = default;
+  GetLocalCounter(Function* func) {
+    analyze(func, func->body);
+  }
+  GetLocalCounter(Function* func, Expression* ast) {
+    analyze(func, ast);
+  }
+
+  void analyze(Function* func) {
+    analyze(func, func->body);
+  }
+  void analyze(Function* func, Expression* ast) {
+    num.resize(func->getNumLocals());
+    std::fill(num.begin(), num.end(), 0);
+    walk(ast);
+  }
+
+  void visitGetLocal(GetLocal *curr) {
+    num[curr->index]++;
+  }
+};
+
+struct UnneededSetRemover : public PostWalker<UnneededSetRemover> {
+  PassOptions& passOptions;
+
+  GetLocalCounter* getLocalCounter = nullptr;
+
+  UnneededSetRemover(Function* func, PassOptions& passOptions) : passOptions(passOptions) {
+    GetLocalCounter counter(func);
+    UnneededSetRemover inner(counter, func, passOptions);
+    removed = inner.removed;
+  }
+
+  UnneededSetRemover(GetLocalCounter& getLocalCounter, Function* func, PassOptions& passOptions) : passOptions(passOptions), getLocalCounter(&getLocalCounter) {
+    walk(func->body);
+  }
+
+  bool removed = false;
+
+  void visitSetLocal(SetLocal *curr) {
+    if (getLocalCounter->num[curr->index] == 0) {
+      auto* value = curr->value;
+      if (curr->isTee()) {
+        this->replaceCurrent(value);
+      } else if (EffectAnalyzer(passOptions, curr->value).hasSideEffects()) {
+        Drop* drop = ExpressionManipulator::convert<SetLocal, Drop>(curr);
+        drop->value = value;
+        drop->finalize();
+      } else {
+        ExpressionManipulator::nop(curr);
+      }
+      removed = true;
+    }
+  }
+};
+
+} // namespace wasm
+
+#endif // wasm_ir_local_utils_h
+
diff --git a/src/ir/parents.h b/src/ir/parents.h
new file mode 100644
index 000000000..71f2ae1d4
--- /dev/null
+++ b/src/ir/parents.h
@@ -0,0 +1,44 @@
+/*
+ * Copyright 2019 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.
+ */
+
+#ifndef wasm_ir_parents_h
+#define wasm_ir_parents_h
+
+namespace wasm {
+
+struct Parents {
+  Parents(Expression* expr) {
+    inner.walk(expr);
+  }
+
+  Expression* getParent(Expression* curr) {
+    return inner.parentMap[curr];
+  }
+
+private:
+  struct Inner : public ExpressionStackWalker<Inner, UnifiedExpressionVisitor<Inner>> {
+    void visitExpression(Expression* curr) {
+      parentMap[curr] = getParent();
+    }
+
+    std::map<Expression*, Expression *> parentMap;
+  } inner;
+};
+
+} // namespace wasm
+
+#endif // wasm_ir_parents_h
+