[deoptimizer] Preserve double bit patterns correctly.

src/deoptimizer.h

Index: src/deoptimizer.h
diff --git a/src/deoptimizer.h b/src/deoptimizer.h
index 7d74af9958ff9064c21d3c95a55c105d91830d37..b65d705a16e3b9060f04d301d3620c530f18b36b 100644
--- a/src/deoptimizer.h
+++ b/src/deoptimizer.h
@@ -20,6 +20,37 @@ class DeoptimizedFrameInfo;
 class TranslatedState;
 class RegisterValues;
 
+// Safety wrapper for a 32-bit floating-point value to make sure we don't loose
+// the exact bit pattern during deoptimization when passing this value. Note
+// that there is intentionally no way to construct it from a {float} value.
+class Float32 {
+ public:
+  Float32() : bit_pattern_(0) {}
+  uint32_t get_bits() const { return bit_pattern_; }
+  float get_scalar() const { return bit_cast<float>(bit_pattern_); }
+  static Float32 FromBits(uint32_t bits) { return Float32(bits); }
+
+ private:
+  explicit Float32(uint32_t bit_pattern) : bit_pattern_(bit_pattern) {}
+  uint32_t bit_pattern_;
+};
+
+// Safety wrapper for a 64-bit floating-point value to make sure we don't loose
+// the exact bit pattern during deoptimization when passing this value. Note
+// that there is intentionally no way to construct it from a {double} value.
+class Float64 {
+ public:
+  Float64() : bit_pattern_(0) {}
+  uint64_t get_bits() const { return bit_pattern_; }
+  double get_scalar() const { return bit_cast<double>(bit_pattern_); }
+  bool is_hole_nan() const { return bit_pattern_ == kHoleNanInt64; }
+  static Float64 FromBits(uint64_t bits) { return Float64(bits); }
+
+ private:
+  explicit Float64(uint64_t bit_pattern) : bit_pattern_(bit_pattern) {}
+  uint64_t bit_pattern_;
+};
+
 class TranslatedValue {
  public:
   // Allocation-less getter of the value.
@@ -64,8 +95,8 @@ class TranslatedValue {
   static TranslatedValue NewDeferredObject(TranslatedState* container,
                                            int length, int object_index);
   static TranslatedValue NewDuplicateObject(TranslatedState* container, int id);
-  static TranslatedValue NewFloat(TranslatedState* container, float value);
-  static TranslatedValue NewDouble(TranslatedState* container, double value);
+  static TranslatedValue NewFloat(TranslatedState* container, Float32 value);
+  static TranslatedValue NewDouble(TranslatedState* container, Float64 value);
   static TranslatedValue NewInt32(TranslatedState* container, int32_t value);
   static TranslatedValue NewUInt32(TranslatedState* container, uint32_t value);
   static TranslatedValue NewBool(TranslatedState* container, uint32_t value);
@@ -98,9 +129,9 @@ class TranslatedValue {
     // kind is kInt32.
     int32_t int32_value_;
     // kind is kFloat
-    float float_value_;
+    Float32 float_value_;
     // kind is kDouble
-    double double_value_;
+    Float64 double_value_;
     // kind is kDuplicatedObject or kArgumentsObject or kCapturedObject.
     MaterializedObjectInfo materialization_info_;
   };
@@ -109,8 +140,8 @@ class TranslatedValue {
   Object* raw_literal() const;
   int32_t int32_value() const;
   uint32_t uint32_value() const;
-  float float_value() const;
-  double double_value() const;
+  Float32 float_value() const;
+  Float64 double_value() const;
   int object_length() const;
   int object_index() const;
 };
@@ -298,6 +329,8 @@ class TranslatedState {
   bool GetAdaptedArguments(Handle<JSObject>* result, int frame_index);
 
   static uint32_t GetUInt32Slot(Address fp, int slot_index);
+  static Float32 GetFloatSlot(Address fp, int slot_index);
+  static Float64 GetDoubleSlot(Address fp, int slot_index);
 
   std::vector<TranslatedFrame> frames_;
   Isolate* isolate_;
@@ -652,12 +685,12 @@ class RegisterValues {
     return registers_[n];
   }
 
-  float GetFloatRegister(unsigned n) const {
+  Float32 GetFloatRegister(unsigned n) const {
     DCHECK(n < arraysize(float_registers_));
     return float_registers_[n];
   }
 
-  double GetDoubleRegister(unsigned n) const {
+  Float64 GetDoubleRegister(unsigned n) const {
     DCHECK(n < arraysize(double_registers_));
     return double_registers_[n];
   }
@@ -667,19 +700,24 @@ class RegisterValues {
     registers_[n] = value;
   }
 
-  void SetFloatRegister(unsigned n, float value) {
+  void SetFloatRegister(unsigned n, Float32 value) {
     DCHECK(n < arraysize(float_registers_));
     float_registers_[n] = value;
   }
 
-  void SetDoubleRegister(unsigned n, double value) {
+  void SetDoubleRegister(unsigned n, Float64 value) {
     DCHECK(n < arraysize(double_registers_));
     double_registers_[n] = value;
   }
 
+  // Generated code is writing directly into the below arrays, make sure their
+  // element sizes fit what the machine instructions expect.
+  static_assert(sizeof(Float32) == kFloatSize, "size mismatch");
+  static_assert(sizeof(Float64) == kDoubleSize, "size mismatch");
+
   intptr_t registers_[Register::kNumRegisters];
-  float float_registers_[FloatRegister::kMaxNumRegisters];
-  double double_registers_[DoubleRegister::kMaxNumRegisters];
+  Float32 float_registers_[FloatRegister::kMaxNumRegisters];
+  Float64 double_registers_[DoubleRegister::kMaxNumRegisters];
 };
 
 
@@ -732,7 +770,7 @@ class FrameDescription {
     return register_values_.GetRegister(n);
   }
 
-  double GetDoubleRegister(unsigned n) const {
+  Float64 GetDoubleRegister(unsigned n) const {
     return register_values_.GetDoubleRegister(n);
   }
 
@@ -740,7 +778,7 @@ class FrameDescription {
     register_values_.SetRegister(n, value);
   }
 
-  void SetDoubleRegister(unsigned n, double value) {
+  void SetDoubleRegister(unsigned n, Float64 value) {
     register_values_.SetDoubleRegister(n, value);
   }