[turbofan] Add TruncationMode for TruncateFloat64ToInt32.

src/compiler/machine-operator.h

 // Copyright 2013 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_MACHINE_OPERATOR_H_
 #define V8_COMPILER_MACHINE_OPERATOR_H_
 
 #include "src/base/flags.h"
 #include "src/compiler/machine-type.h"
 
 namespace v8 {
 namespace internal {
 namespace compiler {
 
 // Forward declarations.
 struct MachineOperatorGlobalCache;
 class Operator;
 
+
 // For operators that are not supported on all platforms.
-class OptionalOperator {
+class OptionalOperator final {
  public:
   explicit OptionalOperator(const Operator* op) : op_(op) {}
 
   bool IsSupported() const { return op_ != nullptr; }
   const Operator* op() const {
     DCHECK_NOT_NULL(op_);
     return op_;
   }
 
  private:
-  const Operator* op_;
+  const Operator* const op_;
 };
 
+
+// Supported float64 to int32 truncation modes.
+enum class TruncationMode : uint8_t {
+  kJavaScript,  // ES6 section 7.1.5
+  kRoundToZero  // Round towards zero. Implementation defined for NaN and ovf.
+};
+
+V8_INLINE size_t hash_value(TruncationMode mode) {
+  return static_cast<uint8_t>(mode);
+}
+
+std::ostream& operator<<(std::ostream&, TruncationMode);
+
+TruncationMode TruncationModeOf(Operator const*);
+
+
 // Supported write barrier modes.
 enum WriteBarrierKind { kNoWriteBarrier, kFullWriteBarrier };
 
 std::ostream& operator<<(std::ostream& os, WriteBarrierKind);
 
 
 // A Load needs a MachineType.
 typedef MachineType LoadRepresentation;
 
 
@@ skipping 124 matching lines @@
   const Operator* ChangeFloat64ToInt32();   // narrowing
   const Operator* ChangeFloat64ToUint32();  // narrowing
   const Operator* ChangeInt32ToFloat64();
   const Operator* ChangeInt32ToInt64();
   const Operator* ChangeUint32ToFloat64();
   const Operator* ChangeUint32ToUint64();
 
   // These operators truncate numbers, both changing the representation of
   // the number and mapping multiple input values onto the same output value.
   const Operator* TruncateFloat64ToFloat32();
-  const Operator* TruncateFloat64ToInt32();  // JavaScript semantics.
+  const Operator* TruncateFloat64ToInt32(TruncationMode);
   const Operator* TruncateInt64ToInt32();
 
   // Floating point operators always operate with IEEE 754 round-to-nearest
   // (single-precision).
   const Operator* Float32Add();
   const Operator* Float32Sub();
   const Operator* Float32Mul();
   const Operator* Float32Div();
   const Operator* Float32Sqrt();
 
@@ skipping 100 matching lines @@
 };
 
 
 DEFINE_OPERATORS_FOR_FLAGS(MachineOperatorBuilder::Flags)
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_COMPILER_MACHINE_OPERATOR_H_