Fixes floating point bug in ARM simulator.

runtime/vm/simulator_arm.h

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 // Declares a Simulator for ARM instructions if we are not generating a native
 // ARM binary. This Simulator allows us to run and debug ARM code generation on
 // regular desktop machines.
 // Dart calls into generated code by "calling" the InvokeDartCode stub,
 // which will start execution in the Simulator or forwards to the real entry
 // on a ARM HW platform.
@@ skipping 33 matching lines @@
   // Special case of set_register and get_register to access the raw PC value.
   void set_pc(int32_t value);
   int32_t get_pc() const;
 
   // Accessors for VFP register state.
   void set_sregister(SRegister reg, float value);
   float get_sregister(SRegister reg) const;
   void set_dregister(DRegister reg, double value);
   double get_dregister(DRegister reg) const;
 
+  // When moving integer (rather than floating point) values to/from
+  // the FPU registers, use the _bits calls to avoid gcc taking liberties with
+  // integers that map to such things as NaN floating point values.
+  void set_sregister_bits(SRegister reg, int32_t value);
+  int32_t get_sregister_bits(SRegister reg) const;
+  void set_dregister_bits(DRegister reg, int64_t value);
+  int64_t get_dregister_bits(DRegister reg) const;
+
   // Accessor to the internal simulator stack top.
   uword StackTop() const;
 
   // The isolate's top_exit_frame_info refers to a Dart frame in the simulator
   // stack. The simulator's top_exit_frame_info refers to a C++ frame in the
   // native stack.
   uword top_exit_frame_info() const { return top_exit_frame_info_; }
   void set_top_exit_frame_info(uword value) { top_exit_frame_info_ = value; }
 
   // Call on program start.
@@ skipping 48 matching lines @@
 
   // CPU state.
   int32_t registers_[kNumberOfCpuRegisters];
   bool n_flag_;
   bool z_flag_;
   bool c_flag_;
   bool v_flag_;
 
   // VFP state.
   union {  // S and D register banks are overlapping.
-    float sregisters_[kNumberOfSRegisters];
-    double dregisters_[kNumberOfDRegisters];
+    int32_t sregisters_[kNumberOfSRegisters];
+    int64_t dregisters_[kNumberOfDRegisters];
   };
   bool fp_n_flag_;
   bool fp_z_flag_;
   bool fp_c_flag_;
   bool fp_v_flag_;
 
   // Simulator support.
   char* stack_;
   bool pc_modified_;
   int icount_;
@@ skipping 112 matching lines @@
   }
 
   friend class SimulatorDebugger;
   friend class SimulatorSetjmpBuffer;
   DISALLOW_COPY_AND_ASSIGN(Simulator);
 };
 
 }  // namespace dart
 
 #endif  // VM_SIMULATOR_ARM_H_