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diff --git a/src/ir/numbering.h b/src/ir/numbering.h
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+/*
+ * Copyright 2021 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_numberings_h
+#define wasm_ir_numberings_h
+
+#include "wasm.h"
+
+namespace wasm {
+
+// General value numbering: Returns a number for an expression. Expressions with
+// the same number must be identical in value; expressions with different values
+// might happen to be identical at runtime.
+class ValueNumbering {
+public:
+  // Get the value numbering of an arbitrary expression.
+  Index getValue(Expression* expr) {
+    if (Properties::isConstantExpression(expr)) {
+      return getValue(Properties::getLiterals(expr));
+    } else {
+      auto iter = expressionValues.find(expr);
+      if (iter != expressionValues.end()) {
+        return iter->second;
+      }
+      // TODO: full GVN to check for different expressions with the same value.
+      return expressionValues[expr] = getUniqueValue();
+    }
+  }
+
+  // Get the value numbering of an arbitrary set of constants.
+  Index getValue(Literals lit) {
+    auto iter = literalValues.find(lit);
+    if (iter != literalValues.end()) {
+      return iter->second;
+    }
+    return literalValues[lit] = getUniqueValue();
+  }
+
+  // Return a new unique value. Normally this is called internally, but there
+  // are also use cases for the user of the class to call this, when they want
+  // to get a new value that will not collide with any others.
+  Index getUniqueValue() { return nextValue++; }
+
+private:
+  Index nextValue = 0;
+
+  // Cache the value numbers of literals and expressions.
+  std::unordered_map<Literals, Index> literalValues;
+  std::unordered_map<Expression*, Index> expressionValues;
+};
+
+} // namespace wasm
+
+#endif // wasm_ir_numberings_h