diff --git a/src/compiler/operation-typer.h b/src/compiler/operation-typer.h
new file mode 100644
index 0000000..aa669ac
--- /dev/null
+++ b/src/compiler/operation-typer.h
@@ -0,0 +1,84 @@
+// Copyright 2016 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef V8_COMPILER_OPERATION_TYPER_H_
+#define V8_COMPILER_OPERATION_TYPER_H_
+
+#include "src/base/flags.h"
+#include "src/compiler/opcodes.h"
+
+namespace v8 {
+namespace internal {
+
+class Isolate;
+class RangeType;
+class Type;
+class TypeCache;
+class Zone;
+
+namespace compiler {
+
+class OperationTyper {
+ public:
+  OperationTyper(Isolate* isolate, Zone* zone);
+
+  // Typing Phi.
+  Type* Merge(Type* left, Type* right);
+
+  Type* ToPrimitive(Type* type);
+
+  // Helpers for number operation typing.
+  Type* ToNumber(Type* type);
+  Type* WeakenRange(Type* current_range, Type* previous_range);
+
+  Type* NumericAdd(Type* lhs, Type* rhs);
+  Type* NumericSubtract(Type* lhs, Type* rhs);
+  Type* NumericMultiply(Type* lhs, Type* rhs);
+  Type* NumericDivide(Type* lhs, Type* rhs);
+  Type* NumericModulus(Type* lhs, Type* rhs);
+
+  enum ComparisonOutcomeFlags {
+    kComparisonTrue = 1,
+    kComparisonFalse = 2,
+    kComparisonUndefined = 4
+  };
+
+// Javascript binop typers.
+#define DECLARE_CASE(x) Type* Type##x(Type* lhs, Type* rhs);
+  JS_SIMPLE_BINOP_LIST(DECLARE_CASE)
+#undef DECLARE_CASE
+
+  Type* singleton_false() { return singleton_false_; }
+  Type* singleton_true() { return singleton_true_; }
+  Type* singleton_the_hole() { return singleton_the_hole_; }
+
+ private:
+  typedef base::Flags<ComparisonOutcomeFlags> ComparisonOutcome;
+
+  ComparisonOutcome Invert(ComparisonOutcome);
+  Type* Invert(Type*);
+  Type* FalsifyUndefined(ComparisonOutcome);
+
+  Type* Rangify(Type*);
+  Type* AddRanger(double lhs_min, double lhs_max, double rhs_min,
+                  double rhs_max);
+  Type* SubtractRanger(RangeType* lhs, RangeType* rhs);
+  Type* MultiplyRanger(Type* lhs, Type* rhs);
+  Type* ModulusRanger(RangeType* lhs, RangeType* rhs);
+
+  Zone* zone() { return zone_; }
+
+  Zone* zone_;
+  TypeCache const& cache_;
+
+  Type* singleton_false_;
+  Type* singleton_true_;
+  Type* singleton_the_hole_;
+};
+
+}  // namespace compiler
+}  // namespace internal
+}  // namespace v8
+
+#endif  // V8_COMPILER_OPERATION_TYPER_H_