Drop in v8 r2121

  From: "http://v8.googlecode.com/svn/trunk@2121",
  It matches "svn://chrome-svn/chrome/branches/187/src@18043"

1 files changed, 1688 insertions, 0 deletions

diff --git a/V8Binding/v8/src/arm/simulator-arm.cc b/V8Binding/v8/src/arm/simulator-arm.cc
new file mode 100644
index 0000000..b8b6663
--- /dev/null
+++ b/V8Binding/v8/src/arm/simulator-arm.cc
@@ -0,0 +1,1688 @@
+// Copyright 2008 the V8 project authors. All rights reserved.
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+//       notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+//       copyright notice, this list of conditions and the following
+//       disclaimer in the documentation and/or other materials provided
+//       with the distribution.
+//     * Neither the name of Google Inc. nor the names of its
+//       contributors may be used to endorse or promote products derived
+//       from this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#include <stdlib.h>
+
+#include "v8.h"
+
+#include "disasm.h"
+#include "arm/constants-arm.h"
+#include "arm/simulator-arm.h"
+
+#if !defined(__arm__)
+
+// Only build the simulator if not compiling for real ARM hardware.
+namespace assembler {
+namespace arm {
+
+using ::v8::internal::Object;
+using ::v8::internal::PrintF;
+using ::v8::internal::OS;
+using ::v8::internal::ReadLine;
+using ::v8::internal::DeleteArray;
+
+// This macro provides a platform independent use of sscanf. The reason for
+// SScanF not being implemented in a platform independent was through
+// ::v8::internal::OS in the same way as SNPrintF is that the Windows C Run-Time
+// Library does not provide vsscanf.
+#define SScanF sscanf  // NOLINT
+
+// The Debugger class is used by the simulator while debugging simulated ARM
+// code.
+class Debugger {
+ public:
+  explicit Debugger(Simulator* sim);
+  ~Debugger();
+
+  void Stop(Instr* instr);
+  void Debug();
+
+ private:
+  static const instr_t kBreakpointInstr =
+      ((AL << 28) | (7 << 25) | (1 << 24) | break_point);
+  static const instr_t kNopInstr =
+      ((AL << 28) | (13 << 21));
+
+  Simulator* sim_;
+
+  bool GetValue(char* desc, int32_t* value);
+
+  // Set or delete a breakpoint. Returns true if successful.
+  bool SetBreakpoint(Instr* breakpc);
+  bool DeleteBreakpoint(Instr* breakpc);
+
+  // Undo and redo all breakpoints. This is needed to bracket disassembly and
+  // execution to skip past breakpoints when run from the debugger.
+  void UndoBreakpoints();
+  void RedoBreakpoints();
+};
+
+
+Debugger::Debugger(Simulator* sim) {
+  sim_ = sim;
+}
+
+
+Debugger::~Debugger() {
+}
+
+
+
+#ifdef GENERATED_CODE_COVERAGE
+static FILE* coverage_log = NULL;
+
+
+static void InitializeCoverage() {
+  char* file_name = getenv("V8_GENERATED_CODE_COVERAGE_LOG");
+  if (file_name != NULL) {
+    coverage_log = fopen(file_name, "aw+");
+  }
+}
+
+
+void Debugger::Stop(Instr* instr) {
+  char* str = reinterpret_cast<char*>(instr->InstructionBits() & 0x0fffffff);
+  if (strlen(str) > 0) {
+    if (coverage_log != NULL) {
+      fprintf(coverage_log, "%s\n", str);
+      fflush(coverage_log);
+    }
+    instr->SetInstructionBits(0xe1a00000);  // Overwrite with nop.
+  }
+  sim_->set_pc(sim_->get_pc() + Instr::kInstrSize);
+}
+
+#else  // ndef GENERATED_CODE_COVERAGE
+
+static void InitializeCoverage() {
+}
+
+
+void Debugger::Stop(Instr* instr) {
+  const char* str = (const char*)(instr->InstructionBits() & 0x0fffffff);
+  PrintF("Simulator hit %s\n", str);
+  sim_->set_pc(sim_->get_pc() + Instr::kInstrSize);
+  Debug();
+}
+#endif
+
+
+static const char* reg_names[] = {  "r0",  "r1",  "r2",  "r3",
+                                    "r4",  "r5",  "r6",  "r7",
+                                    "r8",  "r9", "r10", "r11",
+                                   "r12", "r13", "r14", "r15",
+                                    "pc",  "lr",  "sp",  "ip",
+                                    "fp",  "sl", ""};
+
+static int   reg_nums[]  = {           0,     1,     2,     3,
+                                       4,     5,     6,     7,
+                                       8,     9,    10,    11,
+                                      12,    13,    14,    15,
+                                      15,    14,    13,    12,
+                                      11,    10};
+
+
+static int RegNameToRegNum(char* name) {
+  int reg = 0;
+  while (*reg_names[reg] != 0) {
+    if (strcmp(reg_names[reg], name) == 0) {
+      return reg_nums[reg];
+    }
+    reg++;
+  }
+  return -1;
+}
+
+
+bool Debugger::GetValue(char* desc, int32_t* value) {
+  int regnum = RegNameToRegNum(desc);
+  if (regnum >= 0) {
+    if (regnum == 15) {
+      *value = sim_->get_pc();
+    } else {
+      *value = sim_->get_register(regnum);
+    }
+    return true;
+  } else {
+    return SScanF(desc, "%i", value) == 1;
+  }
+  return false;
+}
+
+
+bool Debugger::SetBreakpoint(Instr* breakpc) {
+  // Check if a breakpoint can be set. If not return without any side-effects.
+  if (sim_->break_pc_ != NULL) {
+    return false;
+  }
+
+  // Set the breakpoint.
+  sim_->break_pc_ = breakpc;
+  sim_->break_instr_ = breakpc->InstructionBits();
+  // Not setting the breakpoint instruction in the code itself. It will be set
+  // when the debugger shell continues.
+  return true;
+}
+
+
+bool Debugger::DeleteBreakpoint(Instr* breakpc) {
+  if (sim_->break_pc_ != NULL) {
+    sim_->break_pc_->SetInstructionBits(sim_->break_instr_);
+  }
+
+  sim_->break_pc_ = NULL;
+  sim_->break_instr_ = 0;
+  return true;
+}
+
+
+void Debugger::UndoBreakpoints() {
+  if (sim_->break_pc_ != NULL) {
+    sim_->break_pc_->SetInstructionBits(sim_->break_instr_);
+  }
+}
+
+
+void Debugger::RedoBreakpoints() {
+  if (sim_->break_pc_ != NULL) {
+    sim_->break_pc_->SetInstructionBits(kBreakpointInstr);
+  }
+}
+
+
+void Debugger::Debug() {
+  intptr_t last_pc = -1;
+  bool done = false;
+
+#define COMMAND_SIZE 63
+#define ARG_SIZE 255
+
+#define STR(a) #a
+#define XSTR(a) STR(a)
+
+  char cmd[COMMAND_SIZE + 1];
+  char arg1[ARG_SIZE + 1];
+  char arg2[ARG_SIZE + 1];
+
+  // make sure to have a proper terminating character if reaching the limit
+  cmd[COMMAND_SIZE] = 0;
+  arg1[ARG_SIZE] = 0;
+  arg2[ARG_SIZE] = 0;
+
+  // Undo all set breakpoints while running in the debugger shell. This will
+  // make them invisible to all commands.
+  UndoBreakpoints();
+
+  while (!done) {
+    if (last_pc != sim_->get_pc()) {
+      disasm::NameConverter converter;
+      disasm::Disassembler dasm(converter);
+      // use a reasonably large buffer
+      v8::internal::EmbeddedVector<char, 256> buffer;
+      dasm.InstructionDecode(buffer,
+                             reinterpret_cast<byte*>(sim_->get_pc()));
+      PrintF("  0x%x  %s\n", sim_->get_pc(), buffer.start());
+      last_pc = sim_->get_pc();
+    }
+    char* line = ReadLine("sim> ");
+    if (line == NULL) {
+      break;
+    } else {
+      // Use sscanf to parse the individual parts of the command line. At the
+      // moment no command expects more than two parameters.
+      int args = SScanF(line,
+                        "%" XSTR(COMMAND_SIZE) "s "
+                        "%" XSTR(ARG_SIZE) "s "
+                        "%" XSTR(ARG_SIZE) "s",
+                        cmd, arg1, arg2);
+      if ((strcmp(cmd, "si") == 0) || (strcmp(cmd, "stepi") == 0)) {
+        sim_->InstructionDecode(reinterpret_cast<Instr*>(sim_->get_pc()));
+      } else if ((strcmp(cmd, "c") == 0) || (strcmp(cmd, "cont") == 0)) {
+        // Execute the one instruction we broke at with breakpoints disabled.
+        sim_->InstructionDecode(reinterpret_cast<Instr*>(sim_->get_pc()));
+        // Leave the debugger shell.
+        done = true;
+      } else if ((strcmp(cmd, "p") == 0) || (strcmp(cmd, "print") == 0)) {
+        if (args == 2) {
+          int32_t value;
+          if (GetValue(arg1, &value)) {
+            PrintF("%s: %d 0x%x\n", arg1, value, value);
+          } else {
+            PrintF("%s unrecognized\n", arg1);
+          }
+        } else {
+          PrintF("print value\n");
+        }
+      } else if ((strcmp(cmd, "po") == 0)
+                 || (strcmp(cmd, "printobject") == 0)) {
+        if (args == 2) {
+          int32_t value;
+          if (GetValue(arg1, &value)) {
+            Object* obj = reinterpret_cast<Object*>(value);
+            USE(obj);
+            PrintF("%s: \n", arg1);
+#if defined(DEBUG)
+            obj->PrintLn();
+#endif  // defined(DEBUG)
+          } else {
+            PrintF("%s unrecognized\n", arg1);
+          }
+        } else {
+          PrintF("printobject value\n");
+        }
+      } else if (strcmp(cmd, "disasm") == 0) {
+        disasm::NameConverter converter;
+        disasm::Disassembler dasm(converter);
+        // use a reasonably large buffer
+        v8::internal::EmbeddedVector<char, 256> buffer;
+
+        byte* cur = NULL;
+        byte* end = NULL;
+
+        if (args == 1) {
+          cur = reinterpret_cast<byte*>(sim_->get_pc());
+          end = cur + (10 * Instr::kInstrSize);
+        } else if (args == 2) {
+          int32_t value;
+          if (GetValue(arg1, &value)) {
+            cur = reinterpret_cast<byte*>(value);
+            // no length parameter passed, assume 10 instructions
+            end = cur + (10 * Instr::kInstrSize);
+          }
+        } else {
+          int32_t value1;
+          int32_t value2;
+          if (GetValue(arg1, &value1) && GetValue(arg2, &value2)) {
+            cur = reinterpret_cast<byte*>(value1);
+            end = cur + (value2 * Instr::kInstrSize);
+          }
+        }
+
+        while (cur < end) {
+          dasm.InstructionDecode(buffer, cur);
+          PrintF("  0x%x  %s\n", cur, buffer.start());
+          cur += Instr::kInstrSize;
+        }
+      } else if (strcmp(cmd, "gdb") == 0) {
+        PrintF("relinquishing control to gdb\n");
+        v8::internal::OS::DebugBreak();
+        PrintF("regaining control from gdb\n");
+      } else if (strcmp(cmd, "break") == 0) {
+        if (args == 2) {
+          int32_t value;
+          if (GetValue(arg1, &value)) {
+            if (!SetBreakpoint(reinterpret_cast<Instr*>(value))) {
+              PrintF("setting breakpoint failed\n");
+            }
+          } else {
+            PrintF("%s unrecognized\n", arg1);
+          }
+        } else {
+          PrintF("break addr\n");
+        }
+      } else if (strcmp(cmd, "del") == 0) {
+        if (!DeleteBreakpoint(NULL)) {
+          PrintF("deleting breakpoint failed\n");
+        }
+      } else if (strcmp(cmd, "flags") == 0) {
+        PrintF("N flag: %d; ", sim_->n_flag_);
+        PrintF("Z flag: %d; ", sim_->z_flag_);
+        PrintF("C flag: %d; ", sim_->c_flag_);
+        PrintF("V flag: %d\n", sim_->v_flag_);
+      } else if (strcmp(cmd, "unstop") == 0) {
+        intptr_t stop_pc = sim_->get_pc() - Instr::kInstrSize;
+        Instr* stop_instr = reinterpret_cast<Instr*>(stop_pc);
+        if (stop_instr->ConditionField() == special_condition) {
+          stop_instr->SetInstructionBits(kNopInstr);
+        } else {
+          PrintF("Not at debugger stop.");
+        }
+      } else {
+        PrintF("Unknown command: %s\n", cmd);
+      }
+    }
+    DeleteArray(line);
+  }
+
+  // Add all the breakpoints back to stop execution and enter the debugger
+  // shell when hit.
+  RedoBreakpoints();
+
+#undef COMMAND_SIZE
+#undef ARG_SIZE
+
+#undef STR
+#undef XSTR
+}
+
+
+Simulator::Simulator() {
+  // Setup simulator support first. Some of this information is needed to
+  // setup the architecture state.
+  size_t stack_size = 1 * 1024*1024;  // allocate 1MB for stack
+  stack_ = reinterpret_cast<char*>(malloc(stack_size));
+  pc_modified_ = false;
+  icount_ = 0;
+  break_pc_ = NULL;
+  break_instr_ = 0;
+
+  // Setup architecture state.
+  // All registers are initialized to zero to start with.
+  for (int i = 0; i < num_registers; i++) {
+    registers_[i] = 0;
+  }
+  n_flag_ = false;
+  z_flag_ = false;
+  c_flag_ = false;
+  v_flag_ = false;
+
+  // The sp is initialized to point to the bottom (high address) of the
+  // allocated stack area. To be safe in potential stack underflows we leave
+  // some buffer below.
+  registers_[sp] = reinterpret_cast<int32_t>(stack_) + stack_size - 64;
+  // The lr and pc are initialized to a known bad value that will cause an
+  // access violation if the simulator ever tries to execute it.
+  registers_[pc] = bad_lr;
+  registers_[lr] = bad_lr;
+  InitializeCoverage();
+}
+
+
+// Create one simulator per thread and keep it in thread local storage.
+static v8::internal::Thread::LocalStorageKey simulator_key =
+    v8::internal::Thread::CreateThreadLocalKey();
+
+// Get the active Simulator for the current thread.
+Simulator* Simulator::current() {
+  Simulator* sim = reinterpret_cast<Simulator*>(
+      v8::internal::Thread::GetThreadLocal(simulator_key));
+  if (sim == NULL) {
+    // TODO(146): delete the simulator object when a thread goes away.
+    sim = new Simulator();
+    v8::internal::Thread::SetThreadLocal(simulator_key, sim);
+  }
+  return sim;
+}
+
+
+// Sets the register in the architecture state. It will also deal with updating
+// Simulator internal state for special registers such as PC.
+void Simulator::set_register(int reg, int32_t value) {
+  ASSERT((reg >= 0) && (reg < num_registers));
+  if (reg == pc) {
+    pc_modified_ = true;
+  }
+  registers_[reg] = value;
+}
+
+
+// Get the register from the architecture state. This function does handle
+// the special case of accessing the PC register.
+int32_t Simulator::get_register(int reg) const {
+  ASSERT((reg >= 0) && (reg < num_registers));
+  return registers_[reg] + ((reg == pc) ? Instr::kPCReadOffset : 0);
+}
+
+
+// Raw access to the PC register.
+void Simulator::set_pc(int32_t value) {
+  pc_modified_ = true;
+  registers_[pc] = value;
+}
+
+
+// Raw access to the PC register without the special adjustment when reading.
+int32_t Simulator::get_pc() const {
+  return registers_[pc];
+}
+
+
+// For use in calls that take two double values, constructed from r0, r1, r2
+// and r3.
+void Simulator::GetFpArgs(double* x, double* y) {
+  // We use a char buffer to get around the strict-aliasing rules which
+  // otherwise allow the compiler to optimize away the copy.
+  char buffer[2 * sizeof(registers_[0])];
+  // Registers 0 and 1 -> x.
+  memcpy(buffer, registers_, sizeof(buffer));
+  memcpy(x, buffer, sizeof(buffer));
+  // Registers 2 and 3 -> y.
+  memcpy(buffer, registers_ + 2, sizeof(buffer));
+  memcpy(y, buffer, sizeof(buffer));
+}
+
+
+void Simulator::SetFpResult(const double& result) {
+  char buffer[2 * sizeof(registers_[0])];
+  memcpy(buffer, &result, sizeof(buffer));
+  // result -> registers 0 and 1.
+  memcpy(registers_, buffer, sizeof(buffer));
+}
+
+
+void Simulator::TrashCallerSaveRegisters() {
+  // We don't trash the registers with the return value.
+  registers_[2] = 0x50Bad4U;
+  registers_[3] = 0x50Bad4U;
+  registers_[12] = 0x50Bad4U;
+}
+
+
+// The ARM cannot do unaligned reads and writes.  On some ARM platforms an
+// interrupt is caused.  On others it does a funky rotation thing.  For now we
+// simply disallow unaligned reads, but at some point we may want to move to
+// emulating the rotate behaviour.  Note that simulator runs have the runtime
+// system running directly on the host system and only generated code is
+// executed in the simulator.  Since the host is typically IA32 we will not
+// get the correct ARM-like behaviour on unaligned accesses.
+
+int Simulator::ReadW(int32_t addr, Instr* instr) {
+  if ((addr & 3) == 0) {
+    intptr_t* ptr = reinterpret_cast<intptr_t*>(addr);
+    return *ptr;
+  }
+  PrintF("Unaligned read at %x\n", addr);
+  UNIMPLEMENTED();
+  return 0;
+}
+
+
+void Simulator::WriteW(int32_t addr, int value, Instr* instr) {
+  if ((addr & 3) == 0) {
+    intptr_t* ptr = reinterpret_cast<intptr_t*>(addr);
+    *ptr = value;
+    return;
+  }
+  PrintF("Unaligned write at %x, pc=%p\n", addr, instr);
+  UNIMPLEMENTED();
+}
+
+
+uint16_t Simulator::ReadHU(int32_t addr, Instr* instr) {
+  if ((addr & 1) == 0) {
+    uint16_t* ptr = reinterpret_cast<uint16_t*>(addr);
+    return *ptr;
+  }
+  PrintF("Unaligned read at %x, pc=%p\n", addr, instr);
+  UNIMPLEMENTED();
+  return 0;
+}
+
+
+int16_t Simulator::ReadH(int32_t addr, Instr* instr) {
+  if ((addr & 1) == 0) {
+    int16_t* ptr = reinterpret_cast<int16_t*>(addr);
+    return *ptr;
+  }
+  PrintF("Unaligned read at %x\n", addr);
+  UNIMPLEMENTED();
+  return 0;
+}
+
+
+void Simulator::WriteH(int32_t addr, uint16_t value, Instr* instr) {
+  if ((addr & 1) == 0) {
+    uint16_t* ptr = reinterpret_cast<uint16_t*>(addr);
+    *ptr = value;
+    return;
+  }
+  PrintF("Unaligned write at %x, pc=%p\n", addr, instr);
+  UNIMPLEMENTED();
+}
+
+
+void Simulator::WriteH(int32_t addr, int16_t value, Instr* instr) {
+  if ((addr & 1) == 0) {
+    int16_t* ptr = reinterpret_cast<int16_t*>(addr);
+    *ptr = value;
+    return;
+  }
+  PrintF("Unaligned write at %x, pc=%p\n", addr, instr);
+  UNIMPLEMENTED();
+}
+
+
+uint8_t Simulator::ReadBU(int32_t addr) {
+  uint8_t* ptr = reinterpret_cast<uint8_t*>(addr);
+  return *ptr;
+}
+
+
+int8_t Simulator::ReadB(int32_t addr) {
+  int8_t* ptr = reinterpret_cast<int8_t*>(addr);
+  return *ptr;
+}
+
+
+void Simulator::WriteB(int32_t addr, uint8_t value) {
+  uint8_t* ptr = reinterpret_cast<uint8_t*>(addr);
+  *ptr = value;
+}
+
+
+void Simulator::WriteB(int32_t addr, int8_t value) {
+  int8_t* ptr = reinterpret_cast<int8_t*>(addr);
+  *ptr = value;
+}
+
+
+// Returns the limit of the stack area to enable checking for stack overflows.
+uintptr_t Simulator::StackLimit() const {
+  // Leave a safety margin of 256 bytes to prevent overrunning the stack when
+  // pushing values.
+  return reinterpret_cast<uintptr_t>(stack_) + 256;
+}
+
+
+// Unsupported instructions use Format to print an error and stop execution.
+void Simulator::Format(Instr* instr, const char* format) {
+  PrintF("Simulator found unsupported instruction:\n 0x%x: %s\n",
+         instr, format);
+  UNIMPLEMENTED();
+}
+
+
+// Checks if the current instruction should be executed based on its
+// condition bits.
+bool Simulator::ConditionallyExecute(Instr* instr) {
+  switch (instr->ConditionField()) {
+    case EQ: return z_flag_;
+    case NE: return !z_flag_;
+    case CS: return c_flag_;
+    case CC: return !c_flag_;
+    case MI: return n_flag_;
+    case PL: return !n_flag_;
+    case VS: return v_flag_;
+    case VC: return !v_flag_;
+    case HI: return c_flag_ && !z_flag_;
+    case LS: return !c_flag_ || z_flag_;
+    case GE: return n_flag_ == v_flag_;
+    case LT: return n_flag_ != v_flag_;
+    case GT: return !z_flag_ && (n_flag_ == v_flag_);
+    case LE: return z_flag_ || (n_flag_ != v_flag_);
+    case AL: return true;
+    default: UNREACHABLE();
+  }
+  return false;
+}
+
+
+// Calculate and set the Negative and Zero flags.
+void Simulator::SetNZFlags(int32_t val) {
+  n_flag_ = (val < 0);
+  z_flag_ = (val == 0);
+}
+
+
+// Set the Carry flag.
+void Simulator::SetCFlag(bool val) {
+  c_flag_ = val;
+}
+
+
+// Set the oVerflow flag.
+void Simulator::SetVFlag(bool val) {
+  v_flag_ = val;
+}
+
+
+// Calculate C flag value for additions.
+bool Simulator::CarryFrom(int32_t left, int32_t right) {
+  uint32_t uleft = static_cast<uint32_t>(left);
+  uint32_t uright = static_cast<uint32_t>(right);
+  uint32_t urest  = 0xffffffffU - uleft;
+
+  return (uright > urest);
+}
+
+
+// Calculate C flag value for subtractions.
+bool Simulator::BorrowFrom(int32_t left, int32_t right) {
+  uint32_t uleft = static_cast<uint32_t>(left);
+  uint32_t uright = static_cast<uint32_t>(right);
+
+  return (uright > uleft);
+}
+
+
+// Calculate V flag value for additions and subtractions.
+bool Simulator::OverflowFrom(int32_t alu_out,
+                             int32_t left, int32_t right, bool addition) {
+  bool overflow;
+  if (addition) {
+               // operands have the same sign
+    overflow = ((left >= 0 && right >= 0) || (left < 0 && right < 0))
+               // and operands and result have different sign
+               && ((left < 0 && alu_out >= 0) || (left >= 0 && alu_out < 0));
+  } else {
+               // operands have different signs
+    overflow = ((left < 0 && right >= 0) || (left >= 0 && right < 0))
+               // and first operand and result have different signs
+               && ((left < 0 && alu_out >= 0) || (left >= 0 && alu_out < 0));
+  }
+  return overflow;
+}
+
+
+// Addressing Mode 1 - Data-processing operands:
+// Get the value based on the shifter_operand with register.
+int32_t Simulator::GetShiftRm(Instr* instr, bool* carry_out) {
+  Shift shift = instr->ShiftField();
+  int shift_amount = instr->ShiftAmountField();
+  int32_t result = get_register(instr->RmField());
+  if (instr->Bit(4) == 0) {
+    // by immediate
+    if ((shift == ROR) && (shift_amount == 0)) {
+      UNIMPLEMENTED();
+      return result;
+    } else if (((shift == LSR) || (shift == ASR)) && (shift_amount == 0)) {
+      shift_amount = 32;
+    }
+    switch (shift) {
+      case ASR: {
+        if (shift_amount == 0) {
+          if (result < 0) {
+            result = 0xffffffff;
+            *carry_out = true;
+          } else {
+            result = 0;
+            *carry_out = false;
+          }
+        } else {
+          result >>= (shift_amount - 1);
+          *carry_out = (result & 1) == 1;
+          result >>= 1;
+        }
+        break;
+      }
+
+      case LSL: {
+        if (shift_amount == 0) {
+          *carry_out = c_flag_;
+        } else {
+          result <<= (shift_amount - 1);
+          *carry_out = (result < 0);
+          result <<= 1;
+        }
+        break;
+      }
+
+      case LSR: {
+        if (shift_amount == 0) {
+          result = 0;
+          *carry_out = c_flag_;
+        } else {
+          uint32_t uresult = static_cast<uint32_t>(result);
+          uresult >>= (shift_amount - 1);
+          *carry_out = (uresult & 1) == 1;
+          uresult >>= 1;
+          result = static_cast<int32_t>(uresult);
+        }
+        break;
+      }
+
+      case ROR: {
+        UNIMPLEMENTED();
+        break;
+      }
+
+      default: {
+        UNREACHABLE();
+        break;
+      }
+    }
+  } else {
+    // by register
+    int rs = instr->RsField();
+    shift_amount = get_register(rs) &0xff;
+    switch (shift) {
+      case ASR: {
+        if (shift_amount == 0) {
+          *carry_out = c_flag_;
+        } else if (shift_amount < 32) {
+          result >>= (shift_amount - 1);
+          *carry_out = (result & 1) == 1;
+          result >>= 1;
+        } else {
+          ASSERT(shift_amount >= 32);
+          if (result < 0) {
+            *carry_out = true;
+            result = 0xffffffff;
+          } else {
+            *carry_out = false;
+            result = 0;
+          }
+        }
+        break;
+      }
+
+      case LSL: {
+        if (shift_amount == 0) {
+          *carry_out = c_flag_;
+        } else if (shift_amount < 32) {
+          result <<= (shift_amount - 1);
+          *carry_out = (result < 0);
+          result <<= 1;
+        } else if (shift_amount == 32) {
+          *carry_out = (result & 1) == 1;
+          result = 0;
+        } else {
+          ASSERT(shift_amount > 32);
+          *carry_out = false;
+          result = 0;
+        }
+        break;
+      }
+
+      case LSR: {
+        if (shift_amount == 0) {
+          *carry_out = c_flag_;
+        } else if (shift_amount < 32) {
+          uint32_t uresult = static_cast<uint32_t>(result);
+          uresult >>= (shift_amount - 1);
+          *carry_out = (uresult & 1) == 1;
+          uresult >>= 1;
+          result = static_cast<int32_t>(uresult);
+        } else if (shift_amount == 32) {
+          *carry_out = (result < 0);
+          result = 0;
+        } else {
+          *carry_out = false;
+          result = 0;
+        }
+        break;
+      }
+
+      case ROR: {
+        UNIMPLEMENTED();
+        break;
+      }
+
+      default: {
+        UNREACHABLE();
+        break;
+      }
+    }
+  }
+  return result;
+}
+
+
+// Addressing Mode 1 - Data-processing operands:
+// Get the value based on the shifter_operand with immediate.
+int32_t Simulator::GetImm(Instr* instr, bool* carry_out) {
+  int rotate = instr->RotateField() * 2;
+  int immed8 = instr->Immed8Field();
+  int imm = (immed8 >> rotate) | (immed8 << (32 - rotate));
+  *carry_out = (rotate == 0) ? c_flag_ : (imm < 0);
+  return imm;
+}
+
+
+static int count_bits(int bit_vector) {
+  int count = 0;
+  while (bit_vector != 0) {
+    if ((bit_vector & 1) != 0) {
+      count++;
+    }
+    bit_vector >>= 1;
+  }
+  return count;
+}
+
+
+// Addressing Mode 4 - Load and Store Multiple
+void Simulator::HandleRList(Instr* instr, bool load) {
+  int rn = instr->RnField();
+  int32_t rn_val = get_register(rn);
+  int rlist = instr->RlistField();
+  int num_regs = count_bits(rlist);
+
+  intptr_t start_address = 0;
+  intptr_t end_address = 0;
+  switch (instr->PUField()) {
+    case 0: {
+      // Print("da");
+      UNIMPLEMENTED();
+      break;
+    }
+    case 1: {
+      // Print("ia");
+      start_address = rn_val;
+      end_address = rn_val + (num_regs * 4) - 4;
+      rn_val = rn_val + (num_regs * 4);
+      break;
+    }
+    case 2: {
+      // Print("db");
+      start_address = rn_val - (num_regs * 4);
+      end_address = rn_val - 4;
+      rn_val = start_address;
+      break;
+    }
+    case 3: {
+      // Print("ib");
+      UNIMPLEMENTED();
+      break;
+    }
+    default: {
+      UNREACHABLE();
+      break;
+    }
+  }
+  if (instr->HasW()) {
+    set_register(rn, rn_val);
+  }
+  intptr_t* address = reinterpret_cast<intptr_t*>(start_address);
+  int reg = 0;
+  while (rlist != 0) {
+    if ((rlist & 1) != 0) {
+      if (load) {
+        set_register(reg, *address);
+      } else {
+        *address = get_register(reg);
+      }
+      address += 1;
+    }
+    reg++;
+    rlist >>= 1;
+  }
+  ASSERT(end_address == ((intptr_t)address) - 4);
+}
+
+
+// Calls into the V8 runtime are based on this very simple interface.
+// Note: To be able to return two values from some calls the code in runtime.cc
+// uses the ObjectPair which is essentially two 32-bit values stuffed into a
+// 64-bit value. With the code below we assume that all runtime calls return
+// 64 bits of result. If they don't, the r1 result register contains a bogus
+// value, which is fine because it is caller-saved.
+typedef int64_t (*SimulatorRuntimeCall)(intptr_t arg0, intptr_t arg1);
+
+
+// Software interrupt instructions are used by the simulator to call into the
+// C-based V8 runtime.
+void Simulator::SoftwareInterrupt(Instr* instr) {
+  int swi = instr->SwiField();
+  switch (swi) {
+    case call_rt_r5: {
+      SimulatorRuntimeCall target =
+          reinterpret_cast<SimulatorRuntimeCall>(get_register(r5));
+      intptr_t arg0 = get_register(r0);
+      intptr_t arg1 = get_register(r1);
+      int64_t result = target(arg0, arg1);
+      int32_t lo_res = static_cast<int32_t>(result);
+      int32_t hi_res = static_cast<int32_t>(result >> 32);
+      set_register(r0, lo_res);
+      set_register(r1, hi_res);
+      set_pc(reinterpret_cast<int32_t>(instr) + Instr::kInstrSize);
+      break;
+    }
+    case call_rt_r2: {
+      SimulatorRuntimeCall target =
+          reinterpret_cast<SimulatorRuntimeCall>(get_register(r2));
+      intptr_t arg0 = get_register(r0);
+      intptr_t arg1 = get_register(r1);
+      int64_t result = target(arg0, arg1);
+      int32_t lo_res = static_cast<int32_t>(result);
+      int32_t hi_res = static_cast<int32_t>(result >> 32);
+      set_register(r0, lo_res);
+      set_register(r1, hi_res);
+      set_pc(reinterpret_cast<int32_t>(instr) + Instr::kInstrSize);
+      break;
+    }
+    case break_point: {
+      Debugger dbg(this);
+      dbg.Debug();
+      break;
+    }
+    {
+      double x, y, z;
+    case simulator_fp_add:
+      GetFpArgs(&x, &y);
+      z = x + y;
+      SetFpResult(z);
+      TrashCallerSaveRegisters();
+      set_pc(reinterpret_cast<int32_t>(instr) + Instr::kInstrSize);
+      break;
+    case simulator_fp_sub:
+      GetFpArgs(&x, &y);
+      z = x - y;
+      SetFpResult(z);
+      TrashCallerSaveRegisters();
+      set_pc(reinterpret_cast<int32_t>(instr) + Instr::kInstrSize);
+      break;
+    case simulator_fp_mul:
+      GetFpArgs(&x, &y);
+      z = x * y;
+      SetFpResult(z);
+      TrashCallerSaveRegisters();
+      set_pc(reinterpret_cast<int32_t>(instr) + Instr::kInstrSize);
+      break;
+    }
+    default: {
+      UNREACHABLE();
+      break;
+    }
+  }
+}
+
+
+// Handle execution based on instruction types.
+
+// Instruction types 0 and 1 are both rolled into one function because they
+// only differ in the handling of the shifter_operand.
+void Simulator::DecodeType01(Instr* instr) {
+  int type = instr->TypeField();
+  if ((type == 0) && instr->IsSpecialType0()) {
+    // multiply instruction or extra loads and stores
+    if (instr->Bits(7, 4) == 9) {
+      if (instr->Bit(24) == 0) {
+        // multiply instructions
+        int rd = instr->RdField();
+        int rm = instr->RmField();
+        int rs = instr->RsField();
+        int32_t rs_val = get_register(rs);
+        int32_t rm_val = get_register(rm);
+        if (instr->Bit(23) == 0) {
+          if (instr->Bit(21) == 0) {
+            // Format(instr, "mul'cond's 'rd, 'rm, 'rs");
+            int32_t alu_out = rm_val * rs_val;
+            set_register(rd, alu_out);
+            if (instr->HasS()) {
+              SetNZFlags(alu_out);
+            }
+          } else {
+            Format(instr, "mla'cond's 'rd, 'rm, 'rs, 'rn");
+          }
+        } else {
+          // Format(instr, "'um'al'cond's 'rn, 'rd, 'rs, 'rm");
+          int rn = instr->RnField();
+          int32_t hi_res = 0;
+          int32_t lo_res = 0;
+          if (instr->Bit(22) == 0) {
+            // signed multiply
+            UNIMPLEMENTED();
+          } else {
+            // unsigned multiply
+            uint64_t left_op  = rm_val;
+            uint64_t right_op = rs_val;
+            uint64_t result = left_op * right_op;
+            hi_res = static_cast<int32_t>(result >> 32);
+            lo_res = static_cast<int32_t>(result & 0xffffffff);
+          }
+          set_register(rn, hi_res);
+          set_register(rd, lo_res);
+          if (instr->HasS()) {
+            UNIMPLEMENTED();
+          }
+        }
+      } else {
+        UNIMPLEMENTED();  // not used by V8
+      }
+    } else {
+      // extra load/store instructions
+      int rd = instr->RdField();
+      int rn = instr->RnField();
+      int32_t rn_val = get_register(rn);
+      int32_t addr = 0;
+      if (instr->Bit(22) == 0) {
+        int rm = instr->RmField();
+        int32_t rm_val = get_register(rm);
+        switch (instr->PUField()) {
+          case 0: {
+            // Format(instr, "'memop'cond'sign'h 'rd, ['rn], -'rm");
+            ASSERT(!instr->HasW());
+            addr = rn_val;
+            rn_val -= rm_val;
+            set_register(rn, rn_val);
+            break;
+          }
+          case 1: {
+            // Format(instr, "'memop'cond'sign'h 'rd, ['rn], +'rm");
+            ASSERT(!instr->HasW());
+            addr = rn_val;
+            rn_val += rm_val;
+            set_register(rn, rn_val);
+            break;
+          }
+          case 2: {
+            // Format(instr, "'memop'cond'sign'h 'rd, ['rn, -'rm]'w");
+            rn_val -= rm_val;
+            addr = rn_val;
+            if (instr->HasW()) {
+              set_register(rn, rn_val);
+            }
+            break;
+          }
+          case 3: {
+            // Format(instr, "'memop'cond'sign'h 'rd, ['rn, +'rm]'w");
+            rn_val += rm_val;
+            addr = rn_val;
+            if (instr->HasW()) {
+              set_register(rn, rn_val);
+            }
+            break;
+          }
+          default: {
+            // The PU field is a 2-bit field.
+            UNREACHABLE();
+            break;
+          }
+        }
+      } else {
+        int32_t imm_val = (instr->ImmedHField() << 4) | instr->ImmedLField();
+        switch (instr->PUField()) {
+          case 0: {
+            // Format(instr, "'memop'cond'sign'h 'rd, ['rn], #-'off8");
+            ASSERT(!instr->HasW());
+            addr = rn_val;
+            rn_val -= imm_val;
+            set_register(rn, rn_val);
+            break;
+          }
+          case 1: {
+            // Format(instr, "'memop'cond'sign'h 'rd, ['rn], #+'off8");
+            ASSERT(!instr->HasW());
+            addr = rn_val;
+            rn_val += imm_val;
+            set_register(rn, rn_val);
+            break;
+          }
+          case 2: {
+            // Format(instr, "'memop'cond'sign'h 'rd, ['rn, #-'off8]'w");
+            rn_val -= imm_val;
+            addr = rn_val;
+            if (instr->HasW()) {
+              set_register(rn, rn_val);
+            }
+            break;
+          }
+          case 3: {
+            // Format(instr, "'memop'cond'sign'h 'rd, ['rn, #+'off8]'w");
+            rn_val += imm_val;
+            addr = rn_val;
+            if (instr->HasW()) {
+              set_register(rn, rn_val);
+            }
+            break;
+          }
+          default: {
+            // The PU field is a 2-bit field.
+            UNREACHABLE();
+            break;
+          }
+        }
+      }
+      if (instr->HasH()) {
+        if (instr->HasSign()) {
+          if (instr->HasL()) {
+            int16_t val = ReadH(addr, instr);
+            set_register(rd, val);
+          } else {
+            int16_t val = get_register(rd);
+            WriteH(addr, val, instr);
+          }
+        } else {
+          if (instr->HasL()) {
+            uint16_t val = ReadHU(addr, instr);
+            set_register(rd, val);
+          } else {
+            uint16_t val = get_register(rd);
+            WriteH(addr, val, instr);
+          }
+        }
+      } else {
+        // signed byte loads
+        ASSERT(instr->HasSign());
+        ASSERT(instr->HasL());
+        int8_t val = ReadB(addr);
+        set_register(rd, val);
+      }
+      return;
+    }
+  } else {
+    int rd = instr->RdField();
+    int rn = instr->RnField();
+    int32_t rn_val = get_register(rn);
+    int32_t shifter_operand = 0;
+    bool shifter_carry_out = 0;
+    if (type == 0) {
+      shifter_operand = GetShiftRm(instr, &shifter_carry_out);
+    } else {
+      ASSERT(instr->TypeField() == 1);
+      shifter_operand = GetImm(instr, &shifter_carry_out);
+    }
+    int32_t alu_out;
+
+    switch (instr->OpcodeField()) {
+      case AND: {
+        // Format(instr, "and'cond's 'rd, 'rn, 'shift_rm");
+        // Format(instr, "and'cond's 'rd, 'rn, 'imm");
+        alu_out = rn_val & shifter_operand;
+        set_register(rd, alu_out);
+        if (instr->HasS()) {
+          SetNZFlags(alu_out);
+          SetCFlag(shifter_carry_out);
+        }
+        break;
+      }
+
+      case EOR: {
+        // Format(instr, "eor'cond's 'rd, 'rn, 'shift_rm");
+        // Format(instr, "eor'cond's 'rd, 'rn, 'imm");
+        alu_out = rn_val ^ shifter_operand;
+        set_register(rd, alu_out);
+        if (instr->HasS()) {
+          SetNZFlags(alu_out);
+          SetCFlag(shifter_carry_out);
+        }
+        break;
+      }
+
+      case SUB: {
+        // Format(instr, "sub'cond's 'rd, 'rn, 'shift_rm");
+        // Format(instr, "sub'cond's 'rd, 'rn, 'imm");
+        alu_out = rn_val - shifter_operand;
+        set_register(rd, alu_out);
+        if (instr->HasS()) {
+          SetNZFlags(alu_out);
+          SetCFlag(!BorrowFrom(rn_val, shifter_operand));
+          SetVFlag(OverflowFrom(alu_out, rn_val, shifter_operand, false));
+        }
+        break;
+      }
+
+      case RSB: {
+        // Format(instr, "rsb'cond's 'rd, 'rn, 'shift_rm");
+        // Format(instr, "rsb'cond's 'rd, 'rn, 'imm");
+        alu_out = shifter_operand - rn_val;
+        set_register(rd, alu_out);
+        if (instr->HasS()) {
+          SetNZFlags(alu_out);
+          SetCFlag(!BorrowFrom(shifter_operand, rn_val));
+          SetVFlag(OverflowFrom(alu_out, shifter_operand, rn_val, false));
+        }
+        break;
+      }
+
+      case ADD: {
+        // Format(instr, "add'cond's 'rd, 'rn, 'shift_rm");
+        // Format(instr, "add'cond's 'rd, 'rn, 'imm");
+        alu_out = rn_val + shifter_operand;
+        set_register(rd, alu_out);
+        if (instr->HasS()) {
+          SetNZFlags(alu_out);
+          SetCFlag(CarryFrom(rn_val, shifter_operand));
+          SetVFlag(OverflowFrom(alu_out, rn_val, shifter_operand, true));
+        }
+        break;
+      }
+
+      case ADC: {
+        Format(instr, "adc'cond's 'rd, 'rn, 'shift_rm");
+        Format(instr, "adc'cond's 'rd, 'rn, 'imm");
+        break;
+      }
+
+      case SBC: {
+        Format(instr, "sbc'cond's 'rd, 'rn, 'shift_rm");
+        Format(instr, "sbc'cond's 'rd, 'rn, 'imm");
+        break;
+      }
+
+      case RSC: {
+        Format(instr, "rsc'cond's 'rd, 'rn, 'shift_rm");
+        Format(instr, "rsc'cond's 'rd, 'rn, 'imm");
+        break;
+      }
+
+      case TST: {
+        if (instr->HasS()) {
+          // Format(instr, "tst'cond 'rn, 'shift_rm");
+          // Format(instr, "tst'cond 'rn, 'imm");
+          alu_out = rn_val & shifter_operand;
+          SetNZFlags(alu_out);
+          SetCFlag(shifter_carry_out);
+        } else {
+          UNIMPLEMENTED();
+        }
+        break;
+      }
+
+      case TEQ: {
+        if (instr->HasS()) {
+          // Format(instr, "teq'cond 'rn, 'shift_rm");
+          // Format(instr, "teq'cond 'rn, 'imm");
+          alu_out = rn_val ^ shifter_operand;
+          SetNZFlags(alu_out);
+          SetCFlag(shifter_carry_out);
+        } else {
+          UNIMPLEMENTED();
+        }
+        break;
+      }
+
+      case CMP: {
+        if (instr->HasS()) {
+          // Format(instr, "cmp'cond 'rn, 'shift_rm");
+          // Format(instr, "cmp'cond 'rn, 'imm");
+          alu_out = rn_val - shifter_operand;
+          SetNZFlags(alu_out);
+          SetCFlag(!BorrowFrom(rn_val, shifter_operand));
+          SetVFlag(OverflowFrom(alu_out, rn_val, shifter_operand, false));
+        } else {
+          UNIMPLEMENTED();
+        }
+        break;
+      }
+
+      case CMN: {
+        if (instr->HasS()) {
+          Format(instr, "cmn'cond 'rn, 'shift_rm");
+          Format(instr, "cmn'cond 'rn, 'imm");
+        } else {
+          UNIMPLEMENTED();
+        }
+        break;
+      }
+
+      case ORR: {
+        // Format(instr, "orr'cond's 'rd, 'rn, 'shift_rm");
+        // Format(instr, "orr'cond's 'rd, 'rn, 'imm");
+        alu_out = rn_val | shifter_operand;
+        set_register(rd, alu_out);
+        if (instr->HasS()) {
+          SetNZFlags(alu_out);
+          SetCFlag(shifter_carry_out);
+        }
+        break;
+      }
+
+      case MOV: {
+        // Format(instr, "mov'cond's 'rd, 'shift_rm");
+        // Format(instr, "mov'cond's 'rd, 'imm");
+        alu_out = shifter_operand;
+        set_register(rd, alu_out);
+        if (instr->HasS()) {
+          SetNZFlags(alu_out);
+          SetCFlag(shifter_carry_out);
+        }
+        break;
+      }
+
+      case BIC: {
+        // Format(instr, "bic'cond's 'rd, 'rn, 'shift_rm");
+        // Format(instr, "bic'cond's 'rd, 'rn, 'imm");
+        alu_out = rn_val & ~shifter_operand;
+        set_register(rd, alu_out);
+        if (instr->HasS()) {
+          SetNZFlags(alu_out);
+          SetCFlag(shifter_carry_out);
+        }
+        break;
+      }
+
+      case MVN: {
+        // Format(instr, "mvn'cond's 'rd, 'shift_rm");
+        // Format(instr, "mvn'cond's 'rd, 'imm");
+        alu_out = ~shifter_operand;
+        set_register(rd, alu_out);
+        if (instr->HasS()) {
+          SetNZFlags(alu_out);
+          SetCFlag(shifter_carry_out);
+        }
+        break;
+      }
+
+      default: {
+        UNREACHABLE();
+        break;
+      }
+    }
+  }
+}
+
+
+void Simulator::DecodeType2(Instr* instr) {
+  int rd = instr->RdField();
+  int rn = instr->RnField();
+  int32_t rn_val = get_register(rn);
+  int32_t im_val = instr->Offset12Field();
+  int32_t addr = 0;
+  switch (instr->PUField()) {
+    case 0: {
+      // Format(instr, "'memop'cond'b 'rd, ['rn], #-'off12");
+      ASSERT(!instr->HasW());
+      addr = rn_val;
+      rn_val -= im_val;
+      set_register(rn, rn_val);
+      break;
+    }
+    case 1: {
+      // Format(instr, "'memop'cond'b 'rd, ['rn], #+'off12");
+      ASSERT(!instr->HasW());
+      addr = rn_val;
+      rn_val += im_val;
+      set_register(rn, rn_val);
+      break;
+    }
+    case 2: {
+      // Format(instr, "'memop'cond'b 'rd, ['rn, #-'off12]'w");
+      rn_val -= im_val;
+      addr = rn_val;
+      if (instr->HasW()) {
+        set_register(rn, rn_val);
+      }
+      break;
+    }
+    case 3: {
+      // Format(instr, "'memop'cond'b 'rd, ['rn, #+'off12]'w");
+      rn_val += im_val;
+      addr = rn_val;
+      if (instr->HasW()) {
+        set_register(rn, rn_val);
+      }
+      break;
+    }
+    default: {
+      UNREACHABLE();
+      break;
+    }
+  }
+  if (instr->HasB()) {
+    if (instr->HasL()) {
+      byte val = ReadBU(addr);
+      set_register(rd, val);
+    } else {
+      byte val = get_register(rd);
+      WriteB(addr, val);
+    }
+  } else {
+    if (instr->HasL()) {
+      set_register(rd, ReadW(addr, instr));
+    } else {
+      WriteW(addr, get_register(rd), instr);
+    }
+  }
+}
+
+
+void Simulator::DecodeType3(Instr* instr) {
+  int rd = instr->RdField();
+  int rn = instr->RnField();
+  int32_t rn_val = get_register(rn);
+  bool shifter_carry_out = 0;
+  int32_t shifter_operand = GetShiftRm(instr, &shifter_carry_out);
+  int32_t addr = 0;
+  switch (instr->PUField()) {
+    case 0: {
+      ASSERT(!instr->HasW());
+      Format(instr, "'memop'cond'b 'rd, ['rn], -'shift_rm");
+      break;
+    }
+    case 1: {
+      ASSERT(!instr->HasW());
+      Format(instr, "'memop'cond'b 'rd, ['rn], +'shift_rm");
+      break;
+    }
+    case 2: {
+      // Format(instr, "'memop'cond'b 'rd, ['rn, -'shift_rm]'w");
+      addr = rn_val - shifter_operand;
+      if (instr->HasW()) {
+        set_register(rn, addr);
+      }
+      break;
+    }
+    case 3: {
+      // Format(instr, "'memop'cond'b 'rd, ['rn, +'shift_rm]'w");
+      addr = rn_val + shifter_operand;
+      if (instr->HasW()) {
+        set_register(rn, addr);
+      }
+      break;
+    }
+    default: {
+      UNREACHABLE();
+      break;
+    }
+  }
+  if (instr->HasB()) {
+    UNIMPLEMENTED();
+  } else {
+    if (instr->HasL()) {
+      set_register(rd, ReadW(addr, instr));
+    } else {
+      WriteW(addr, get_register(rd), instr);
+    }
+  }
+}
+
+
+void Simulator::DecodeType4(Instr* instr) {
+  ASSERT(instr->Bit(22) == 0);  // only allowed to be set in privileged mode
+  if (instr->HasL()) {
+    // Format(instr, "ldm'cond'pu 'rn'w, 'rlist");
+    HandleRList(instr, true);
+  } else {
+    // Format(instr, "stm'cond'pu 'rn'w, 'rlist");
+    HandleRList(instr, false);
+  }
+}
+
+
+void Simulator::DecodeType5(Instr* instr) {
+  // Format(instr, "b'l'cond 'target");
+  int off = (instr->SImmed24Field() << 2) + 8;
+  intptr_t pc = get_pc();
+  if (instr->HasLink()) {
+    set_register(lr, pc + Instr::kInstrSize);
+  }
+  set_pc(pc+off);
+}
+
+
+void Simulator::DecodeType6(Instr* instr) {
+  UNIMPLEMENTED();
+}
+
+
+void Simulator::DecodeType7(Instr* instr) {
+  if (instr->Bit(24) == 1) {
+    // Format(instr, "swi 'swi");
+    SoftwareInterrupt(instr);
+  } else {
+    UNIMPLEMENTED();
+  }
+}
+
+
+// Executes the current instruction.
+void Simulator::InstructionDecode(Instr* instr) {
+  pc_modified_ = false;
+  if (instr->ConditionField() == special_condition) {
+    Debugger dbg(this);
+    dbg.Stop(instr);
+    return;
+  }
+  if (::v8::internal::FLAG_trace_sim) {
+    disasm::NameConverter converter;
+    disasm::Disassembler dasm(converter);
+    // use a reasonably large buffer
+    v8::internal::EmbeddedVector<char, 256> buffer;
+    dasm.InstructionDecode(buffer,
+                           reinterpret_cast<byte*>(instr));
+    PrintF("  0x%x  %s\n", instr, buffer.start());
+  }
+  if (ConditionallyExecute(instr)) {
+    switch (instr->TypeField()) {
+      case 0:
+      case 1: {
+        DecodeType01(instr);
+        break;
+      }
+      case 2: {
+        DecodeType2(instr);
+        break;
+      }
+      case 3: {
+        DecodeType3(instr);
+        break;
+      }
+      case 4: {
+        DecodeType4(instr);
+        break;
+      }
+      case 5: {
+        DecodeType5(instr);
+        break;
+      }
+      case 6: {
+        DecodeType6(instr);
+        break;
+      }
+      case 7: {
+        DecodeType7(instr);
+        break;
+      }
+      default: {
+        UNIMPLEMENTED();
+        break;
+      }
+    }
+  }
+  if (!pc_modified_) {
+    set_register(pc, reinterpret_cast<int32_t>(instr) + Instr::kInstrSize);
+  }
+}
+
+
+//
+void Simulator::Execute() {
+  // Get the PC to simulate. Cannot use the accessor here as we need the
+  // raw PC value and not the one used as input to arithmetic instructions.
+  int program_counter = get_pc();
+
+  if (::v8::internal::FLAG_stop_sim_at == 0) {
+    // Fast version of the dispatch loop without checking whether the simulator
+    // should be stopping at a particular executed instruction.
+    while (program_counter != end_sim_pc) {
+      Instr* instr = reinterpret_cast<Instr*>(program_counter);
+      icount_++;
+      InstructionDecode(instr);
+      program_counter = get_pc();
+    }
+  } else {
+    // FLAG_stop_sim_at is at the non-default value. Stop in the debugger when
+    // we reach the particular instuction count.
+    while (program_counter != end_sim_pc) {
+      Instr* instr = reinterpret_cast<Instr*>(program_counter);
+      icount_++;
+      if (icount_ == ::v8::internal::FLAG_stop_sim_at) {
+        Debugger dbg(this);
+        dbg.Debug();
+      } else {
+        InstructionDecode(instr);
+      }
+      program_counter = get_pc();
+    }
+  }
+}
+
+
+Object* Simulator::Call(int32_t entry, int32_t p0, int32_t p1, int32_t p2,
+                        int32_t p3, int32_t p4) {
+  // Setup parameters
+  set_register(r0, p0);
+  set_register(r1, p1);
+  set_register(r2, p2);
+  set_register(r3, p3);
+  intptr_t* stack_pointer = reinterpret_cast<intptr_t*>(get_register(sp));
+  *(--stack_pointer) = p4;
+  set_register(sp, reinterpret_cast<int32_t>(stack_pointer));
+
+  // Prepare to execute the code at entry
+  set_register(pc, entry);
+  // Put down marker for end of simulation. The simulator will stop simulation
+  // when the PC reaches this value. By saving the "end simulation" value into
+  // the LR the simulation stops when returning to this call point.
+  set_register(lr, end_sim_pc);
+
+  // Remember the values of callee-saved registers.
+  // The code below assumes that r9 is not used as sb (static base) in
+  // simulator code and therefore is regarded as a callee-saved register.
+  int32_t r4_val = get_register(r4);
+  int32_t r5_val = get_register(r5);
+  int32_t r6_val = get_register(r6);
+  int32_t r7_val = get_register(r7);
+  int32_t r8_val = get_register(r8);
+  int32_t r9_val = get_register(r9);
+  int32_t r10_val = get_register(r10);
+  int32_t r11_val = get_register(r11);
+
+  // Setup the callee-saved registers with a known value. To be able to check
+  // that they are preserved properly across JS execution.
+  int32_t callee_saved_value = icount_;
+  set_register(r4, callee_saved_value);
+  set_register(r5, callee_saved_value);
+  set_register(r6, callee_saved_value);
+  set_register(r7, callee_saved_value);
+  set_register(r8, callee_saved_value);
+  set_register(r9, callee_saved_value);
+  set_register(r10, callee_saved_value);
+  set_register(r11, callee_saved_value);
+
+  // Start the simulation
+  Execute();
+
+  // Check that the callee-saved registers have been preserved.
+  CHECK_EQ(get_register(r4), callee_saved_value);
+  CHECK_EQ(get_register(r5), callee_saved_value);
+  CHECK_EQ(get_register(r6), callee_saved_value);
+  CHECK_EQ(get_register(r7), callee_saved_value);
+  CHECK_EQ(get_register(r8), callee_saved_value);
+  CHECK_EQ(get_register(r9), callee_saved_value);
+  CHECK_EQ(get_register(r10), callee_saved_value);
+  CHECK_EQ(get_register(r11), callee_saved_value);
+
+  // Restore callee-saved registers with the original value.
+  set_register(r4, r4_val);
+  set_register(r5, r5_val);
+  set_register(r6, r6_val);
+  set_register(r7, r7_val);
+  set_register(r8, r8_val);
+  set_register(r9, r9_val);
+  set_register(r10, r10_val);
+  set_register(r11, r11_val);
+
+  int result = get_register(r0);
+  return reinterpret_cast<Object*>(result);
+}
+
+} }  // namespace assembler::arm
+
+#endif  // !defined(__arm__)