Adding upstream version 124.0.1.upstream/124.0.1

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 4785 insertions, 0 deletions

diff --git a/js/src/jit/riscv64/Simulator-riscv64.cpp b/js/src/jit/riscv64/Simulator-riscv64.cpp
new file mode 100644
index 0000000000..aa0c350c7d
--- /dev/null
+++ b/js/src/jit/riscv64/Simulator-riscv64.cpp
@@ -0,0 +1,4785 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ * vim: set ts=8 sts=2 et sw=2 tw=80: */
+// Copyright 2021 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.
+#ifdef JS_SIMULATOR_RISCV64
+#  include "jit/riscv64/Simulator-riscv64.h"
+
+#  include "mozilla/Casting.h"
+#  include "mozilla/FloatingPoint.h"
+#  include "mozilla/IntegerPrintfMacros.h"
+#  include "mozilla/Likely.h"
+#  include "mozilla/MathAlgorithms.h"
+
+#  include <float.h>
+#  include <iostream>
+#  include <limits>
+
+#  include "jit/AtomicOperations.h"
+#  include "jit/riscv64/Assembler-riscv64.h"
+#  include "js/Conversions.h"
+#  include "js/UniquePtr.h"
+#  include "js/Utility.h"
+#  include "threading/LockGuard.h"
+#  include "vm/JSContext.h"
+#  include "vm/Runtime.h"
+#  include "wasm/WasmInstance.h"
+#  include "wasm/WasmSignalHandlers.h"
+
+#  define I8(v) static_cast<int8_t>(v)
+#  define I16(v) static_cast<int16_t>(v)
+#  define U16(v) static_cast<uint16_t>(v)
+#  define I32(v) static_cast<int32_t>(v)
+#  define U32(v) static_cast<uint32_t>(v)
+#  define I64(v) static_cast<int64_t>(v)
+#  define U64(v) static_cast<uint64_t>(v)
+#  define I128(v) static_cast<__int128_t>(v)
+#  define U128(v) static_cast<__uint128_t>(v)
+
+#  define REGIx_FORMAT PRIx64
+#  define REGId_FORMAT PRId64
+
+#  define I32_CHECK(v)                   \
+    ({                                   \
+      MOZ_ASSERT(I64(I32(v)) == I64(v)); \
+      I32((v));                          \
+    })
+
+namespace js {
+namespace jit {
+
+bool Simulator::FLAG_trace_sim = false;
+bool Simulator::FLAG_debug_sim = false;
+bool Simulator::FLAG_riscv_trap_to_simulator_debugger = false;
+bool Simulator::FLAG_riscv_print_watchpoint = false;
+
+static void UNIMPLEMENTED() {
+  printf("UNIMPLEMENTED instruction.\n");
+  MOZ_CRASH();
+}
+static void UNREACHABLE() {
+  printf("UNREACHABLE instruction.\n");
+  MOZ_CRASH();
+}
+#  define UNSUPPORTED()                                                \
+    std::cout << "Unrecognized instruction [@pc=0x" << std::hex        \
+              << registers_[pc] << "]: 0x" << instr_.InstructionBits() \
+              << std::endl;                                            \
+    printf("Unsupported instruction.\n");                              \
+    MOZ_CRASH();
+
+static char* ReadLine(const char* prompt) {
+  UniqueChars result;
+  char lineBuf[256];
+  int offset = 0;
+  bool keepGoing = true;
+  fprintf(stdout, "%s", prompt);
+  fflush(stdout);
+  while (keepGoing) {
+    if (fgets(lineBuf, sizeof(lineBuf), stdin) == nullptr) {
+      // fgets got an error. Just give up.
+      return nullptr;
+    }
+    int len = strlen(lineBuf);
+    if (len > 0 && lineBuf[len - 1] == '\n') {
+      // Since we read a new line we are done reading the line. This
+      // will exit the loop after copying this buffer into the result.
+      keepGoing = false;
+    }
+    if (!result) {
+      // Allocate the initial result and make room for the terminating '\0'
+      result.reset(js_pod_malloc<char>(len + 1));
+      if (!result) {
+        return nullptr;
+      }
+    } else {
+      // Allocate a new result with enough room for the new addition.
+      int new_len = offset + len + 1;
+      char* new_result = js_pod_malloc<char>(new_len);
+      if (!new_result) {
+        return nullptr;
+      }
+      // Copy the existing input into the new array and set the new
+      // array as the result.
+      memcpy(new_result, result.get(), offset * sizeof(char));
+      result.reset(new_result);
+    }
+    // Copy the newly read line into the result.
+    memcpy(result.get() + offset, lineBuf, len * sizeof(char));
+    offset += len;
+  }
+
+  MOZ_ASSERT(result);
+  result[offset] = '\0';
+  return result.release();
+}
+
+// -----------------------------------------------------------------------------
+// Riscv assembly various constants.
+
+// C/C++ argument slots size.
+const int kCArgSlotCount = 0;
+const int kCArgsSlotsSize = kCArgSlotCount * sizeof(uintptr_t);
+const int kBranchReturnOffset = 2 * kInstrSize;
+
+class CachePage {
+ public:
+  static const int LINE_VALID = 0;
+  static const int LINE_INVALID = 1;
+
+  static const int kPageShift = 12;
+  static const int kPageSize = 1 << kPageShift;
+  static const int kPageMask = kPageSize - 1;
+  static const int kLineShift = 2;  // The cache line is only 4 bytes right now.
+  static const int kLineLength = 1 << kLineShift;
+  static const int kLineMask = kLineLength - 1;
+
+  CachePage() { memset(&validity_map_, LINE_INVALID, sizeof(validity_map_)); }
+
+  char* validityByte(int offset) {
+    return &validity_map_[offset >> kLineShift];
+  }
+
+  char* cachedData(int offset) { return &data_[offset]; }
+
+ private:
+  char data_[kPageSize];  // The cached data.
+  static const int kValidityMapSize = kPageSize >> kLineShift;
+  char validity_map_[kValidityMapSize];  // One byte per line.
+};
+
+// Protects the icache() and redirection() properties of the
+// Simulator.
+class AutoLockSimulatorCache : public LockGuard<Mutex> {
+  using Base = LockGuard<Mutex>;
+
+ public:
+  explicit AutoLockSimulatorCache()
+      : Base(SimulatorProcess::singleton_->cacheLock_) {}
+};
+
+mozilla::Atomic<size_t, mozilla::ReleaseAcquire>
+    SimulatorProcess::ICacheCheckingDisableCount(
+        1);  // Checking is disabled by default.
+SimulatorProcess* SimulatorProcess::singleton_ = nullptr;
+
+int64_t Simulator::StopSimAt = -1;
+
+static bool IsFlag(const char* found, const char* flag) {
+  return strlen(found) == strlen(flag) && strcmp(found, flag) == 0;
+}
+
+Simulator* Simulator::Create() {
+  auto sim = MakeUnique<Simulator>();
+  if (!sim) {
+    return nullptr;
+  }
+
+  if (!sim->init()) {
+    return nullptr;
+  }
+
+  int64_t stopAt;
+  char* stopAtStr = getenv("RISCV_SIM_STOP_AT");
+  if (stopAtStr && sscanf(stopAtStr, "%" PRIi64, &stopAt) == 1) {
+    fprintf(stderr, "\nStopping simulation at icount %" PRIi64 "\n", stopAt);
+    Simulator::StopSimAt = stopAt;
+  }
+  char* str = getenv("RISCV_TRACE_SIM");
+  if (str != nullptr && IsFlag(str, "true")) {
+    FLAG_trace_sim = true;
+  }
+
+  return sim.release();
+}
+
+void Simulator::Destroy(Simulator* sim) { js_delete(sim); }
+
+#  if JS_CODEGEN_RISCV64
+void Simulator::TraceRegWr(int64_t value, TraceType t) {
+  if (FLAG_trace_sim) {
+    union {
+      int64_t fmt_int64;
+      int32_t fmt_int32[2];
+      float fmt_float[2];
+      double fmt_double;
+    } v;
+    v.fmt_int64 = value;
+
+    switch (t) {
+      case WORD:
+        SNPrintF(trace_buf_,
+                 "%016" REGIx_FORMAT "    (%" PRId64 ")    int32:%" PRId32
+                 " uint32:%" PRIu32,
+                 v.fmt_int64, icount_, v.fmt_int32[0], v.fmt_int32[0]);
+        break;
+      case DWORD:
+        SNPrintF(trace_buf_,
+                 "%016" REGIx_FORMAT "    (%" PRId64 ")    int64:%" REGId_FORMAT
+                 " uint64:%" PRIu64,
+                 value, icount_, value, value);
+        break;
+      case FLOAT:
+        SNPrintF(trace_buf_, "%016" REGIx_FORMAT "    (%" PRId64 ")    flt:%e",
+                 v.fmt_int64, icount_, v.fmt_float[0]);
+        break;
+      case DOUBLE:
+        SNPrintF(trace_buf_, "%016" REGIx_FORMAT "    (%" PRId64 ")    dbl:%e",
+                 v.fmt_int64, icount_, v.fmt_double);
+        break;
+      default:
+        UNREACHABLE();
+    }
+  }
+}
+
+#  elif JS_CODEGEN_RISCV32
+template <typename T>
+void Simulator::TraceRegWr(T value, TraceType t) {
+  if (::v8::internal::FLAG_trace_sim) {
+    union {
+      int32_t fmt_int32;
+      float fmt_float;
+      double fmt_double;
+    } v;
+    if (t != DOUBLE) {
+      v.fmt_int32 = value;
+    } else {
+      DCHECK_EQ(sizeof(T), 8);
+      v.fmt_double = value;
+    }
+    switch (t) {
+      case WORD:
+        SNPrintF(trace_buf_,
+                 "%016" REGIx_FORMAT "    (%" PRId64 ")    int32:%" REGId_FORMAT
+                 " uint32:%" PRIu32,
+                 v.fmt_int32, icount_, v.fmt_int32, v.fmt_int32);
+        break;
+      case FLOAT:
+        SNPrintF(trace_buf_, "%016" REGIx_FORMAT "    (%" PRId64 ")    flt:%e",
+                 v.fmt_int32, icount_, v.fmt_float);
+        break;
+      case DOUBLE:
+        SNPrintF(trace_buf_, "%016" PRIx64 "    (%" PRId64 ")    dbl:%e",
+                 static_cast<int64_t>(v.fmt_double), icount_, v.fmt_double);
+        break;
+      default:
+        UNREACHABLE();
+    }
+  }
+}
+#  endif
+// The RiscvDebugger class is used by the simulator while debugging simulated
+// code.
+class RiscvDebugger {
+ public:
+  explicit RiscvDebugger(Simulator* sim) : sim_(sim) {}
+
+  void Debug();
+  // Print all registers with a nice formatting.
+  void PrintRegs(char name_prefix, int start_index, int end_index);
+  void printAllRegs();
+  void printAllRegsIncludingFPU();
+
+  static const Instr kNopInstr = 0x0;
+
+ private:
+  Simulator* sim_;
+
+  int64_t GetRegisterValue(int regnum);
+  int64_t GetFPURegisterValue(int regnum);
+  float GetFPURegisterValueFloat(int regnum);
+  double GetFPURegisterValueDouble(int regnum);
+#  ifdef CAN_USE_RVV_INSTRUCTIONS
+  __int128_t GetVRegisterValue(int regnum);
+#  endif
+  bool GetValue(const char* desc, int64_t* value);
+};
+
+int64_t RiscvDebugger::GetRegisterValue(int regnum) {
+  if (regnum == Simulator::Register::kNumSimuRegisters) {
+    return sim_->get_pc();
+  } else {
+    return sim_->getRegister(regnum);
+  }
+}
+
+int64_t RiscvDebugger::GetFPURegisterValue(int regnum) {
+  if (regnum == Simulator::FPURegister::kNumFPURegisters) {
+    return sim_->get_pc();
+  } else {
+    return sim_->getFpuRegister(regnum);
+  }
+}
+
+float RiscvDebugger::GetFPURegisterValueFloat(int regnum) {
+  if (regnum == Simulator::FPURegister::kNumFPURegisters) {
+    return sim_->get_pc();
+  } else {
+    return sim_->getFpuRegisterFloat(regnum);
+  }
+}
+
+double RiscvDebugger::GetFPURegisterValueDouble(int regnum) {
+  if (regnum == Simulator::FPURegister::kNumFPURegisters) {
+    return sim_->get_pc();
+  } else {
+    return sim_->getFpuRegisterDouble(regnum);
+  }
+}
+
+#  ifdef CAN_USE_RVV_INSTRUCTIONS
+__int128_t RiscvDebugger::GetVRegisterValue(int regnum) {
+  if (regnum == kNumVRegisters) {
+    return sim_->get_pc();
+  } else {
+    return sim_->get_vregister(regnum);
+  }
+}
+#  endif
+
+bool RiscvDebugger::GetValue(const char* desc, int64_t* value) {
+  int regnum = Registers::FromName(desc);
+  int fpuregnum = FloatRegisters::FromName(desc);
+
+  if (regnum != Registers::invalid_reg) {
+    *value = GetRegisterValue(regnum);
+    return true;
+  } else if (fpuregnum != FloatRegisters::invalid_reg) {
+    *value = GetFPURegisterValue(fpuregnum);
+    return true;
+  } else if (strncmp(desc, "0x", 2) == 0) {
+    return sscanf(desc + 2, "%" SCNx64, reinterpret_cast<int64_t*>(value)) == 1;
+  } else {
+    return sscanf(desc, "%" SCNu64, reinterpret_cast<int64_t*>(value)) == 1;
+  }
+}
+
+#  define REG_INFO(name)                               \
+    name, GetRegisterValue(Registers::FromName(name)), \
+        GetRegisterValue(Registers::FromName(name))
+
+void RiscvDebugger::PrintRegs(char name_prefix, int start_index,
+                              int end_index) {
+  EmbeddedVector<char, 10> name1, name2;
+  MOZ_ASSERT(name_prefix == 'a' || name_prefix == 't' || name_prefix == 's');
+  MOZ_ASSERT(start_index >= 0 && end_index <= 99);
+  int num_registers = (end_index - start_index) + 1;
+  for (int i = 0; i < num_registers / 2; i++) {
+    SNPrintF(name1, "%c%d", name_prefix, start_index + 2 * i);
+    SNPrintF(name2, "%c%d", name_prefix, start_index + 2 * i + 1);
+    printf("%3s: 0x%016" REGIx_FORMAT "  %14" REGId_FORMAT
+           " \t%3s: 0x%016" REGIx_FORMAT "  %14" REGId_FORMAT " \n",
+           REG_INFO(name1.start()), REG_INFO(name2.start()));
+  }
+  if (num_registers % 2 == 1) {
+    SNPrintF(name1, "%c%d", name_prefix, end_index);
+    printf("%3s: 0x%016" REGIx_FORMAT "  %14" REGId_FORMAT " \n",
+           REG_INFO(name1.start()));
+  }
+}
+
+void RiscvDebugger::printAllRegs() {
+  printf("\n");
+  // ra, sp, gp
+  printf("%3s: 0x%016" REGIx_FORMAT " %14" REGId_FORMAT
+         "\t%3s: 0x%016" REGIx_FORMAT " %14" REGId_FORMAT
+         "\t%3s: 0x%016" REGIx_FORMAT " %14" REGId_FORMAT "\n",
+         REG_INFO("ra"), REG_INFO("sp"), REG_INFO("gp"));
+
+  // tp, fp, pc
+  printf("%3s: 0x%016" REGIx_FORMAT " %14" REGId_FORMAT
+         "\t%3s: 0x%016" REGIx_FORMAT " %14" REGId_FORMAT
+         "\t%3s: 0x%016" REGIx_FORMAT " %14" REGId_FORMAT "\n",
+         REG_INFO("tp"), REG_INFO("fp"), REG_INFO("pc"));
+
+  // print register a0, .., a7
+  PrintRegs('a', 0, 7);
+  // print registers s1, ..., s11
+  PrintRegs('s', 1, 11);
+  // print registers t0, ..., t6
+  PrintRegs('t', 0, 6);
+}
+
+#  undef REG_INFO
+
+void RiscvDebugger::printAllRegsIncludingFPU() {
+#  define FPU_REG_INFO(n)                               \
+    FloatRegisters::GetName(n), GetFPURegisterValue(n), \
+        GetFPURegisterValueDouble(n)
+
+  printAllRegs();
+
+  printf("\n\n");
+  // f0, f1, f2, ... f31.
+  MOZ_ASSERT(kNumFPURegisters % 2 == 0);
+  for (int i = 0; i < kNumFPURegisters; i += 2)
+    printf("%3s: 0x%016" PRIx64 "  %16.4e \t%3s: 0x%016" PRIx64 "  %16.4e\n",
+           FPU_REG_INFO(i), FPU_REG_INFO(i + 1));
+#  undef FPU_REG_INFO
+}
+
+void RiscvDebugger::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];
+  char* argv[3] = {cmd, arg1, arg2};
+
+  // Make sure to have a proper terminating character if reaching the limit.
+  cmd[COMMAND_SIZE] = 0;
+  arg1[ARG_SIZE] = 0;
+  arg2[ARG_SIZE] = 0;
+
+  while (!done && (sim_->get_pc() != Simulator::end_sim_pc)) {
+    if (last_pc != sim_->get_pc()) {
+      disasm::NameConverter converter;
+      disasm::Disassembler dasm(converter);
+      // Use a reasonably large buffer.
+      EmbeddedVector<char, 256> buffer;
+      dasm.InstructionDecode(buffer, reinterpret_cast<byte*>(sim_->get_pc()));
+      printf("  0x%016" REGIx_FORMAT "   %s\n", sim_->get_pc(), buffer.start());
+      last_pc = sim_->get_pc();
+    }
+    char* line = ReadLine("sim> ");
+    if (line == nullptr) {
+      break;
+    } else {
+      char* last_input = sim_->lastDebuggerInput();
+      if (strcmp(line, "\n") == 0 && last_input != nullptr) {
+        line = last_input;
+      } else {
+        // Ownership is transferred to sim_;
+        sim_->setLastDebuggerInput(line);
+      }
+      // Use sscanf to parse the individual parts of the command line. At the
+      // moment no command expects more than two parameters.
+      int argc = 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)) {
+        SimInstruction* instr =
+            reinterpret_cast<SimInstruction*>(sim_->get_pc());
+        if (!(instr->IsTrap()) ||
+            instr->InstructionBits() == rtCallRedirInstr) {
+          sim_->icount_++;
+          sim_->InstructionDecode(
+              reinterpret_cast<Instruction*>(sim_->get_pc()));
+        } else {
+          // Allow si to jump over generated breakpoints.
+          printf("/!\\ Jumping over generated breakpoint.\n");
+          sim_->set_pc(sim_->get_pc() + kInstrSize);
+        }
+      } else if ((strcmp(cmd, "c") == 0) || (strcmp(cmd, "cont") == 0)) {
+        // Leave the debugger shell.
+        done = true;
+      } else if ((strcmp(cmd, "p") == 0) || (strcmp(cmd, "print") == 0)) {
+        if (argc == 2) {
+          int64_t value;
+          int64_t fvalue;
+          double dvalue;
+          if (strcmp(arg1, "all") == 0) {
+            printAllRegs();
+          } else if (strcmp(arg1, "allf") == 0) {
+            printAllRegsIncludingFPU();
+          } else {
+            int regnum = Registers::FromName(arg1);
+            int fpuregnum = FloatRegisters::FromName(arg1);
+#  ifdef CAN_USE_RVV_INSTRUCTIONS
+            int vregnum = VRegisters::FromName(arg1);
+#  endif
+            if (regnum != Registers::invalid_reg) {
+              value = GetRegisterValue(regnum);
+              printf("%s: 0x%08" REGIx_FORMAT "  %" REGId_FORMAT "  \n", arg1,
+                     value, value);
+            } else if (fpuregnum != FloatRegisters::invalid_reg) {
+              fvalue = GetFPURegisterValue(fpuregnum);
+              dvalue = GetFPURegisterValueDouble(fpuregnum);
+              printf("%3s: 0x%016" PRIx64 "  %16.4e\n",
+                     FloatRegisters::GetName(fpuregnum), fvalue, dvalue);
+#  ifdef CAN_USE_RVV_INSTRUCTIONS
+            } else if (vregnum != kInvalidVRegister) {
+              __int128_t v = GetVRegisterValue(vregnum);
+              printf("\t%s:0x%016" REGIx_FORMAT "%016" REGIx_FORMAT "\n",
+                     VRegisters::GetName(vregnum), (uint64_t)(v >> 64),
+                     (uint64_t)v);
+#  endif
+            } else {
+              printf("%s unrecognized\n", arg1);
+            }
+          }
+        } else {
+          if (argc == 3) {
+            if (strcmp(arg2, "single") == 0) {
+              int64_t value;
+              float fvalue;
+              int fpuregnum = FloatRegisters::FromName(arg1);
+
+              if (fpuregnum != FloatRegisters::invalid_reg) {
+                value = GetFPURegisterValue(fpuregnum);
+                value &= 0xFFFFFFFFUL;
+                fvalue = GetFPURegisterValueFloat(fpuregnum);
+                printf("%s: 0x%08" PRIx64 "  %11.4e\n", arg1, value, fvalue);
+              } else {
+                printf("%s unrecognized\n", arg1);
+              }
+            } else {
+              printf("print <fpu register> single\n");
+            }
+          } else {
+            printf("print <register> or print <fpu register> single\n");
+          }
+        }
+      } else if ((strcmp(cmd, "po") == 0) ||
+                 (strcmp(cmd, "printobject") == 0)) {
+        UNIMPLEMENTED();
+      } else if (strcmp(cmd, "stack") == 0 || strcmp(cmd, "mem") == 0) {
+        int64_t* cur = nullptr;
+        int64_t* end = nullptr;
+        int next_arg = 1;
+        if (argc < 2) {
+          printf("Need to specify <address> to memhex command\n");
+          continue;
+        }
+        int64_t value;
+        if (!GetValue(arg1, &value)) {
+          printf("%s unrecognized\n", arg1);
+          continue;
+        }
+        cur = reinterpret_cast<int64_t*>(value);
+        next_arg++;
+
+        int64_t words;
+        if (argc == next_arg) {
+          words = 10;
+        } else {
+          if (!GetValue(argv[next_arg], &words)) {
+            words = 10;
+          }
+        }
+        end = cur + words;
+
+        while (cur < end) {
+          printf("  0x%012" PRIxPTR " :  0x%016" REGIx_FORMAT
+                 "  %14" REGId_FORMAT " ",
+                 reinterpret_cast<intptr_t>(cur), *cur, *cur);
+          printf("\n");
+          cur++;
+        }
+      } else if ((strcmp(cmd, "watch") == 0)) {
+        if (argc < 2) {
+          printf("Need to specify <address> to mem command\n");
+          continue;
+        }
+        int64_t value;
+        if (!GetValue(arg1, &value)) {
+          printf("%s unrecognized\n", arg1);
+          continue;
+        }
+        sim_->watch_address_ = reinterpret_cast<int64_t*>(value);
+        sim_->watch_value_ = *(sim_->watch_address_);
+      } else if ((strcmp(cmd, "disasm") == 0) || (strcmp(cmd, "dpc") == 0) ||
+                 (strcmp(cmd, "di") == 0)) {
+        disasm::NameConverter converter;
+        disasm::Disassembler dasm(converter);
+        // Use a reasonably large buffer.
+        EmbeddedVector<char, 256> buffer;
+
+        byte* cur = nullptr;
+        byte* end = nullptr;
+
+        if (argc == 1) {
+          cur = reinterpret_cast<byte*>(sim_->get_pc());
+          end = cur + (10 * kInstrSize);
+        } else if (argc == 2) {
+          auto regnum = Registers::FromName(arg1);
+          if (regnum != Registers::invalid_reg || strncmp(arg1, "0x", 2) == 0) {
+            // The argument is an address or a register name.
+            sreg_t value;
+            if (GetValue(arg1, &value)) {
+              cur = reinterpret_cast<byte*>(value);
+              // Disassemble 10 instructions at <arg1>.
+              end = cur + (10 * kInstrSize);
+            }
+          } else {
+            // The argument is the number of instructions.
+            sreg_t value;
+            if (GetValue(arg1, &value)) {
+              cur = reinterpret_cast<byte*>(sim_->get_pc());
+              // Disassemble <arg1> instructions.
+              end = cur + (value * kInstrSize);
+            }
+          }
+        } else {
+          sreg_t value1;
+          sreg_t value2;
+          if (GetValue(arg1, &value1) && GetValue(arg2, &value2)) {
+            cur = reinterpret_cast<byte*>(value1);
+            end = cur + (value2 * kInstrSize);
+          }
+        }
+        while (cur < end) {
+          dasm.InstructionDecode(buffer, cur);
+          printf("  0x%08" PRIxPTR "   %s\n", reinterpret_cast<intptr_t>(cur),
+                 buffer.start());
+          cur += kInstrSize;
+        }
+      } else if (strcmp(cmd, "trace") == 0) {
+        Simulator::FLAG_trace_sim = true;
+        Simulator::FLAG_riscv_print_watchpoint = true;
+      } else if (strcmp(cmd, "break") == 0 || strcmp(cmd, "b") == 0 ||
+                 strcmp(cmd, "tbreak") == 0) {
+        bool is_tbreak = strcmp(cmd, "tbreak") == 0;
+        if (argc == 2) {
+          int64_t value;
+          if (GetValue(arg1, &value)) {
+            sim_->SetBreakpoint(reinterpret_cast<SimInstruction*>(value),
+                                is_tbreak);
+          } else {
+            printf("%s unrecognized\n", arg1);
+          }
+        } else {
+          sim_->ListBreakpoints();
+          printf("Use `break <address>` to set or disable a breakpoint\n");
+          printf(
+              "Use `tbreak <address>` to set or disable a temporary "
+              "breakpoint\n");
+        }
+      } else if (strcmp(cmd, "flags") == 0) {
+        printf("No flags on RISC-V !\n");
+      } else if (strcmp(cmd, "stop") == 0) {
+        int64_t value;
+        if (argc == 3) {
+          // Print information about all/the specified breakpoint(s).
+          if (strcmp(arg1, "info") == 0) {
+            if (strcmp(arg2, "all") == 0) {
+              printf("Stop information:\n");
+              for (uint32_t i = kMaxWatchpointCode + 1; i <= kMaxStopCode;
+                   i++) {
+                sim_->printStopInfo(i);
+              }
+            } else if (GetValue(arg2, &value)) {
+              sim_->printStopInfo(value);
+            } else {
+              printf("Unrecognized argument.\n");
+            }
+          } else if (strcmp(arg1, "enable") == 0) {
+            // Enable all/the specified breakpoint(s).
+            if (strcmp(arg2, "all") == 0) {
+              for (uint32_t i = kMaxWatchpointCode + 1; i <= kMaxStopCode;
+                   i++) {
+                sim_->enableStop(i);
+              }
+            } else if (GetValue(arg2, &value)) {
+              sim_->enableStop(value);
+            } else {
+              printf("Unrecognized argument.\n");
+            }
+          } else if (strcmp(arg1, "disable") == 0) {
+            // Disable all/the specified breakpoint(s).
+            if (strcmp(arg2, "all") == 0) {
+              for (uint32_t i = kMaxWatchpointCode + 1; i <= kMaxStopCode;
+                   i++) {
+                sim_->disableStop(i);
+              }
+            } else if (GetValue(arg2, &value)) {
+              sim_->disableStop(value);
+            } else {
+              printf("Unrecognized argument.\n");
+            }
+          }
+        } else {
+          printf("Wrong usage. Use help command for more information.\n");
+        }
+      } else if ((strcmp(cmd, "stat") == 0) || (strcmp(cmd, "st") == 0)) {
+        UNIMPLEMENTED();
+      } else if ((strcmp(cmd, "h") == 0) || (strcmp(cmd, "help") == 0)) {
+        printf("cont (alias 'c')\n");
+        printf("  Continue execution\n");
+        printf("stepi (alias 'si')\n");
+        printf("  Step one instruction\n");
+        printf("print (alias 'p')\n");
+        printf("  print <register>\n");
+        printf("  Print register content\n");
+        printf("  Use register name 'all' to print all GPRs\n");
+        printf("  Use register name 'allf' to print all GPRs and FPRs\n");
+        printf("printobject (alias 'po')\n");
+        printf("  printobject <register>\n");
+        printf("  Print an object from a register\n");
+        printf("stack\n");
+        printf("  stack [<words>]\n");
+        printf("  Dump stack content, default dump 10 words)\n");
+        printf("mem\n");
+        printf("  mem <address> [<words>]\n");
+        printf("  Dump memory content, default dump 10 words)\n");
+        printf("watch\n");
+        printf("  watch <address> \n");
+        printf("  watch memory content.)\n");
+        printf("flags\n");
+        printf("  print flags\n");
+        printf("disasm (alias 'di')\n");
+        printf("  disasm [<instructions>]\n");
+        printf("  disasm [<address/register>] (e.g., disasm pc) \n");
+        printf("  disasm [[<address/register>] <instructions>]\n");
+        printf("  Disassemble code, default is 10 instructions\n");
+        printf("  from pc\n");
+        printf("gdb \n");
+        printf("  Return to gdb if the simulator was started with gdb\n");
+        printf("break (alias 'b')\n");
+        printf("  break : list all breakpoints\n");
+        printf("  break <address> : set / enable / disable a breakpoint.\n");
+        printf("tbreak\n");
+        printf("  tbreak : list all breakpoints\n");
+        printf(
+            "  tbreak <address> : set / enable / disable a temporary "
+            "breakpoint.\n");
+        printf("  Set a breakpoint enabled only for one stop. \n");
+        printf("stop feature:\n");
+        printf("  Description:\n");
+        printf("    Stops are debug instructions inserted by\n");
+        printf("    the Assembler::stop() function.\n");
+        printf("    When hitting a stop, the Simulator will\n");
+        printf("    stop and give control to the Debugger.\n");
+        printf("    All stop codes are watched:\n");
+        printf("    - They can be enabled / disabled: the Simulator\n");
+        printf("       will / won't stop when hitting them.\n");
+        printf("    - The Simulator keeps track of how many times they \n");
+        printf("      are met. (See the info command.) Going over a\n");
+        printf("      disabled stop still increases its counter. \n");
+        printf("  Commands:\n");
+        printf("    stop info all/<code> : print infos about number <code>\n");
+        printf("      or all stop(s).\n");
+        printf("    stop enable/disable all/<code> : enables / disables\n");
+        printf("      all or number <code> stop(s)\n");
+      } else {
+        printf("Unknown command: %s\n", cmd);
+      }
+    }
+  }
+
+#  undef COMMAND_SIZE
+#  undef ARG_SIZE
+
+#  undef STR
+#  undef XSTR
+}
+
+void Simulator::SetBreakpoint(SimInstruction* location, bool is_tbreak) {
+  for (unsigned i = 0; i < breakpoints_.size(); i++) {
+    if (breakpoints_.at(i).location == location) {
+      if (breakpoints_.at(i).is_tbreak != is_tbreak) {
+        printf("Change breakpoint at %p to %s breakpoint\n",
+               reinterpret_cast<void*>(location),
+               is_tbreak ? "temporary" : "regular");
+        breakpoints_.at(i).is_tbreak = is_tbreak;
+        return;
+      }
+      printf("Existing breakpoint at %p was %s\n",
+             reinterpret_cast<void*>(location),
+             breakpoints_.at(i).enabled ? "disabled" : "enabled");
+      breakpoints_.at(i).enabled = !breakpoints_.at(i).enabled;
+      return;
+    }
+  }
+  Breakpoint new_breakpoint = {location, true, is_tbreak};
+  breakpoints_.push_back(new_breakpoint);
+  printf("Set a %sbreakpoint at %p\n", is_tbreak ? "temporary " : "",
+         reinterpret_cast<void*>(location));
+}
+
+void Simulator::ListBreakpoints() {
+  printf("Breakpoints:\n");
+  for (unsigned i = 0; i < breakpoints_.size(); i++) {
+    printf("%p  : %s %s\n",
+           reinterpret_cast<void*>(breakpoints_.at(i).location),
+           breakpoints_.at(i).enabled ? "enabled" : "disabled",
+           breakpoints_.at(i).is_tbreak ? ": temporary" : "");
+  }
+}
+
+void Simulator::CheckBreakpoints() {
+  bool hit_a_breakpoint = false;
+  bool is_tbreak = false;
+  SimInstruction* pc_ = reinterpret_cast<SimInstruction*>(get_pc());
+  for (unsigned i = 0; i < breakpoints_.size(); i++) {
+    if ((breakpoints_.at(i).location == pc_) && breakpoints_.at(i).enabled) {
+      hit_a_breakpoint = true;
+      if (breakpoints_.at(i).is_tbreak) {
+        // Disable a temporary breakpoint.
+        is_tbreak = true;
+        breakpoints_.at(i).enabled = false;
+      }
+      break;
+    }
+  }
+  if (hit_a_breakpoint) {
+    printf("Hit %sa breakpoint at %p.\n", is_tbreak ? "and disabled " : "",
+           reinterpret_cast<void*>(pc_));
+    RiscvDebugger dbg(this);
+    dbg.Debug();
+  }
+}
+
+static bool AllOnOnePage(uintptr_t start, int size) {
+  intptr_t start_page = (start & ~CachePage::kPageMask);
+  intptr_t end_page = ((start + size) & ~CachePage::kPageMask);
+  return start_page == end_page;
+}
+
+void Simulator::setLastDebuggerInput(char* input) {
+  js_free(lastDebuggerInput_);
+  lastDebuggerInput_ = input;
+}
+
+static CachePage* GetCachePageLocked(SimulatorProcess::ICacheMap& i_cache,
+                                     void* page) {
+  SimulatorProcess::ICacheMap::AddPtr p = i_cache.lookupForAdd(page);
+  if (p) {
+    return p->value();
+  }
+  AutoEnterOOMUnsafeRegion oomUnsafe;
+  CachePage* new_page = js_new<CachePage>();
+  if (!new_page || !i_cache.add(p, page, new_page)) {
+    oomUnsafe.crash("Simulator CachePage");
+  }
+  return new_page;
+}
+
+// Flush from start up to and not including start + size.
+static void FlushOnePageLocked(SimulatorProcess::ICacheMap& i_cache,
+                               intptr_t start, int size) {
+  MOZ_ASSERT(size <= CachePage::kPageSize);
+  MOZ_ASSERT(AllOnOnePage(start, size - 1));
+  MOZ_ASSERT((start & CachePage::kLineMask) == 0);
+  MOZ_ASSERT((size & CachePage::kLineMask) == 0);
+  void* page = reinterpret_cast<void*>(start & (~CachePage::kPageMask));
+  int offset = (start & CachePage::kPageMask);
+  CachePage* cache_page = GetCachePageLocked(i_cache, page);
+  char* valid_bytemap = cache_page->validityByte(offset);
+  memset(valid_bytemap, CachePage::LINE_INVALID, size >> CachePage::kLineShift);
+}
+
+static void FlushICacheLocked(SimulatorProcess::ICacheMap& i_cache,
+                              void* start_addr, size_t size) {
+  intptr_t start = reinterpret_cast<intptr_t>(start_addr);
+  int intra_line = (start & CachePage::kLineMask);
+  start -= intra_line;
+  size += intra_line;
+  size = ((size - 1) | CachePage::kLineMask) + 1;
+  int offset = (start & CachePage::kPageMask);
+  while (!AllOnOnePage(start, size - 1)) {
+    int bytes_to_flush = CachePage::kPageSize - offset;
+    FlushOnePageLocked(i_cache, start, bytes_to_flush);
+    start += bytes_to_flush;
+    size -= bytes_to_flush;
+    MOZ_ASSERT((start & CachePage::kPageMask) == 0);
+    offset = 0;
+  }
+  if (size != 0) {
+    FlushOnePageLocked(i_cache, start, size);
+  }
+}
+
+/* static */
+void SimulatorProcess::checkICacheLocked(SimInstruction* instr) {
+  intptr_t address = reinterpret_cast<intptr_t>(instr);
+  void* page = reinterpret_cast<void*>(address & (~CachePage::kPageMask));
+  void* line = reinterpret_cast<void*>(address & (~CachePage::kLineMask));
+  int offset = (address & CachePage::kPageMask);
+  CachePage* cache_page = GetCachePageLocked(icache(), page);
+  char* cache_valid_byte = cache_page->validityByte(offset);
+  bool cache_hit = (*cache_valid_byte == CachePage::LINE_VALID);
+  char* cached_line = cache_page->cachedData(offset & ~CachePage::kLineMask);
+
+  if (cache_hit) {
+    // Check that the data in memory matches the contents of the I-cache.
+    int cmpret = memcmp(reinterpret_cast<void*>(instr),
+                        cache_page->cachedData(offset), kInstrSize);
+    MOZ_ASSERT(cmpret == 0);
+  } else {
+    // Cache miss.  Load memory into the cache.
+    memcpy(cached_line, line, CachePage::kLineLength);
+    *cache_valid_byte = CachePage::LINE_VALID;
+  }
+}
+
+HashNumber SimulatorProcess::ICacheHasher::hash(const Lookup& l) {
+  return U32(reinterpret_cast<uintptr_t>(l)) >> 2;
+}
+
+bool SimulatorProcess::ICacheHasher::match(const Key& k, const Lookup& l) {
+  MOZ_ASSERT((reinterpret_cast<intptr_t>(k) & CachePage::kPageMask) == 0);
+  MOZ_ASSERT((reinterpret_cast<intptr_t>(l) & CachePage::kPageMask) == 0);
+  return k == l;
+}
+
+/* static */
+void SimulatorProcess::FlushICache(void* start_addr, size_t size) {
+  if (!ICacheCheckingDisableCount) {
+    AutoLockSimulatorCache als;
+    js::jit::FlushICacheLocked(icache(), start_addr, size);
+  }
+}
+
+Simulator::Simulator() {
+  // Set up simulator support first. Some of this information is needed to
+  // setup the architecture state.
+
+  // Note, allocation and anything that depends on allocated memory is
+  // deferred until init(), in order to handle OOM properly.
+
+  stack_ = nullptr;
+  stackLimit_ = 0;
+  pc_modified_ = false;
+  icount_ = 0;
+  break_count_ = 0;
+  break_pc_ = nullptr;
+  break_instr_ = 0;
+  single_stepping_ = false;
+  single_step_callback_ = nullptr;
+  single_step_callback_arg_ = nullptr;
+
+  // Set up architecture state.
+  // All registers are initialized to zero to start with.
+  for (int i = 0; i < Simulator::Register::kNumSimuRegisters; i++) {
+    registers_[i] = 0;
+  }
+  for (int i = 0; i < Simulator::FPURegister::kNumFPURegisters; i++) {
+    FPUregisters_[i] = 0;
+  }
+  FCSR_ = 0;
+  LLBit_ = false;
+  LLAddr_ = 0;
+  lastLLValue_ = 0;
+
+  // The ra 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_ra;
+  registers_[ra] = bad_ra;
+
+  for (int i = 0; i < kNumExceptions; i++) {
+    exceptions[i] = 0;
+  }
+
+  lastDebuggerInput_ = nullptr;
+}
+
+bool Simulator::init() {
+  // Allocate 2MB for the stack. Note that we will only use 1MB, see below.
+  static const size_t stackSize = 2 * 1024 * 1024;
+  stack_ = js_pod_malloc<char>(stackSize);
+  if (!stack_) {
+    return false;
+  }
+
+  // Leave a safety margin of 1MB to prevent overrunning the stack when
+  // pushing values (total stack size is 2MB).
+  stackLimit_ = reinterpret_cast<uintptr_t>(stack_) + 1024 * 1024;
+
+  // 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<int64_t>(stack_) + stackSize - 64;
+
+  return true;
+}
+
+// When the generated code calls an external reference we need to catch that in
+// the simulator.  The external reference will be a function compiled for the
+// host architecture.  We need to call that function instead of trying to
+// execute it with the simulator.  We do that by redirecting the external
+// reference to a swi (software-interrupt) instruction that is handled by
+// the simulator.  We write the original destination of the jump just at a known
+// offset from the swi instruction so the simulator knows what to call.
+class Redirection {
+  friend class SimulatorProcess;
+
+  // sim's lock must already be held.
+  Redirection(void* nativeFunction, ABIFunctionType type)
+      : nativeFunction_(nativeFunction),
+        swiInstruction_(rtCallRedirInstr),
+        type_(type),
+        next_(nullptr) {
+    next_ = SimulatorProcess::redirection();
+    if (!SimulatorProcess::ICacheCheckingDisableCount) {
+      FlushICacheLocked(SimulatorProcess::icache(), addressOfSwiInstruction(),
+                        kInstrSize);
+    }
+    SimulatorProcess::setRedirection(this);
+  }
+
+ public:
+  void* addressOfSwiInstruction() { return &swiInstruction_; }
+  void* nativeFunction() const { return nativeFunction_; }
+  ABIFunctionType type() const { return type_; }
+
+  static Redirection* Get(void* nativeFunction, ABIFunctionType type) {
+    AutoLockSimulatorCache als;
+
+    Redirection* current = SimulatorProcess::redirection();
+    for (; current != nullptr; current = current->next_) {
+      if (current->nativeFunction_ == nativeFunction) {
+        MOZ_ASSERT(current->type() == type);
+        return current;
+      }
+    }
+
+    // Note: we can't use js_new here because the constructor is private.
+    AutoEnterOOMUnsafeRegion oomUnsafe;
+    Redirection* redir = js_pod_malloc<Redirection>(1);
+    if (!redir) {
+      oomUnsafe.crash("Simulator redirection");
+    }
+    new (redir) Redirection(nativeFunction, type);
+    return redir;
+  }
+
+  static Redirection* FromSwiInstruction(Instruction* swiInstruction) {
+    uint8_t* addrOfSwi = reinterpret_cast<uint8_t*>(swiInstruction);
+    uint8_t* addrOfRedirection =
+        addrOfSwi - offsetof(Redirection, swiInstruction_);
+    return reinterpret_cast<Redirection*>(addrOfRedirection);
+  }
+
+ private:
+  void* nativeFunction_;
+  uint32_t swiInstruction_;
+  ABIFunctionType type_;
+  Redirection* next_;
+};
+
+Simulator::~Simulator() { js_free(stack_); }
+
+SimulatorProcess::SimulatorProcess()
+    : cacheLock_(mutexid::SimulatorCacheLock), redirection_(nullptr) {
+  if (getenv("MIPS_SIM_ICACHE_CHECKS")) {
+    ICacheCheckingDisableCount = 0;
+  }
+}
+
+SimulatorProcess::~SimulatorProcess() {
+  Redirection* r = redirection_;
+  while (r) {
+    Redirection* next = r->next_;
+    js_delete(r);
+    r = next;
+  }
+}
+
+/* static */
+void* Simulator::RedirectNativeFunction(void* nativeFunction,
+                                        ABIFunctionType type) {
+  Redirection* redirection = Redirection::Get(nativeFunction, type);
+  return redirection->addressOfSwiInstruction();
+}
+
+// Get the active Simulator for the current thread.
+Simulator* Simulator::Current() {
+  JSContext* cx = TlsContext.get();
+  MOZ_ASSERT(CurrentThreadCanAccessRuntime(cx->runtime()));
+  return cx->simulator();
+}
+
+// Sets the register in the architecture state. It will also deal with updating
+// Simulator internal state for special registers such as PC.
+void Simulator::setRegister(int reg, int64_t value) {
+  MOZ_ASSERT((reg >= 0) && (reg < Simulator::Register::kNumSimuRegisters));
+  if (reg == pc) {
+    pc_modified_ = true;
+  }
+
+  // Zero register always holds 0.
+  registers_[reg] = (reg == 0) ? 0 : value;
+}
+
+void Simulator::setFpuRegister(int fpureg, int64_t value) {
+  MOZ_ASSERT((fpureg >= 0) &&
+             (fpureg < Simulator::FPURegister::kNumFPURegisters));
+  FPUregisters_[fpureg] = value;
+}
+
+void Simulator::setFpuRegisterLo(int fpureg, int32_t value) {
+  MOZ_ASSERT((fpureg >= 0) &&
+             (fpureg < Simulator::FPURegister::kNumFPURegisters));
+  *mozilla::BitwiseCast<int32_t*>(&FPUregisters_[fpureg]) = value;
+}
+
+void Simulator::setFpuRegisterHi(int fpureg, int32_t value) {
+  MOZ_ASSERT((fpureg >= 0) &&
+             (fpureg < Simulator::FPURegister::kNumFPURegisters));
+  *((mozilla::BitwiseCast<int32_t*>(&FPUregisters_[fpureg])) + 1) = value;
+}
+
+void Simulator::setFpuRegisterFloat(int fpureg, float value) {
+  MOZ_ASSERT((fpureg >= 0) &&
+             (fpureg < Simulator::FPURegister::kNumFPURegisters));
+  *mozilla::BitwiseCast<int64_t*>(&FPUregisters_[fpureg]) = box_float(value);
+}
+
+void Simulator::setFpuRegisterFloat(int fpureg, Float32 value) {
+  MOZ_ASSERT((fpureg >= 0) && (fpureg < kNumFPURegisters));
+  Float64 t = Float64::FromBits(box_float(value.get_bits()));
+  memcpy(&FPUregisters_[fpureg], &t, 8);
+}
+
+void Simulator::setFpuRegisterDouble(int fpureg, double value) {
+  MOZ_ASSERT((fpureg >= 0) &&
+             (fpureg < Simulator::FPURegister::kNumFPURegisters));
+  *mozilla::BitwiseCast<double*>(&FPUregisters_[fpureg]) = value;
+}
+
+void Simulator::setFpuRegisterDouble(int fpureg, Float64 value) {
+  MOZ_ASSERT((fpureg >= 0) && (fpureg < kNumFPURegisters));
+  memcpy(&FPUregisters_[fpureg], &value, 8);
+}
+
+// Get the register from the architecture state. This function does handle
+// the special case of accessing the PC register.
+int64_t Simulator::getRegister(int reg) const {
+  MOZ_ASSERT((reg >= 0) && (reg < Simulator::Register::kNumSimuRegisters));
+  if (reg == 0) {
+    return 0;
+  }
+  return registers_[reg] + ((reg == pc) ? SimInstruction::kPCReadOffset : 0);
+}
+
+int64_t Simulator::getFpuRegister(int fpureg) const {
+  MOZ_ASSERT((fpureg >= 0) &&
+             (fpureg < Simulator::FPURegister::kNumFPURegisters));
+  return FPUregisters_[fpureg];
+}
+
+int32_t Simulator::getFpuRegisterLo(int fpureg) const {
+  MOZ_ASSERT((fpureg >= 0) &&
+             (fpureg < Simulator::FPURegister::kNumFPURegisters));
+  return *mozilla::BitwiseCast<int32_t*>(&FPUregisters_[fpureg]);
+}
+
+int32_t Simulator::getFpuRegisterHi(int fpureg) const {
+  MOZ_ASSERT((fpureg >= 0) &&
+             (fpureg < Simulator::FPURegister::kNumFPURegisters));
+  return *((mozilla::BitwiseCast<int32_t*>(&FPUregisters_[fpureg])) + 1);
+}
+
+float Simulator::getFpuRegisterFloat(int fpureg) const {
+  MOZ_ASSERT((fpureg >= 0) &&
+             (fpureg < Simulator::FPURegister::kNumFPURegisters));
+  return *mozilla::BitwiseCast<float*>(&FPUregisters_[fpureg]);
+}
+
+Float32 Simulator::getFpuRegisterFloat32(int fpureg) const {
+  MOZ_ASSERT((fpureg >= 0) && (fpureg < kNumFPURegisters));
+  if (!is_boxed_float(FPUregisters_[fpureg])) {
+    return Float32::FromBits(0x7ffc0000);
+  }
+  return Float32::FromBits(
+      *bit_cast<uint32_t*>(const_cast<int64_t*>(&FPUregisters_[fpureg])));
+}
+
+double Simulator::getFpuRegisterDouble(int fpureg) const {
+  MOZ_ASSERT((fpureg >= 0) &&
+             (fpureg < Simulator::FPURegister::kNumFPURegisters));
+  return *mozilla::BitwiseCast<double*>(&FPUregisters_[fpureg]);
+}
+
+Float64 Simulator::getFpuRegisterFloat64(int fpureg) const {
+  MOZ_ASSERT((fpureg >= 0) && (fpureg < kNumFPURegisters));
+  return Float64::FromBits(FPUregisters_[fpureg]);
+}
+
+void Simulator::setCallResultDouble(double result) {
+  setFpuRegisterDouble(fa0, result);
+}
+
+void Simulator::setCallResultFloat(float result) {
+  setFpuRegisterFloat(fa0, result);
+}
+
+void Simulator::setCallResult(int64_t res) { setRegister(a0, res); }
+
+void Simulator::setCallResult(__int128_t res) {
+  setRegister(a0, I64(res));
+  setRegister(a1, I64(res >> 64));
+}
+
+// Raw access to the PC register.
+void Simulator::set_pc(int64_t value) {
+  pc_modified_ = true;
+  registers_[pc] = value;
+}
+
+bool Simulator::has_bad_pc() const {
+  return ((registers_[pc] == bad_ra) || (registers_[pc] == end_sim_pc));
+}
+
+// Raw access to the PC register without the special adjustment when reading.
+int64_t Simulator::get_pc() const { return registers_[pc]; }
+
+JS::ProfilingFrameIterator::RegisterState Simulator::registerState() {
+  wasm::RegisterState state;
+  state.pc = (void*)get_pc();
+  state.fp = (void*)getRegister(fp);
+  state.sp = (void*)getRegister(sp);
+  state.lr = (void*)getRegister(ra);
+  return state;
+}
+
+void Simulator::HandleWasmTrap() {
+  uint8_t* newPC;
+  if (wasm::HandleIllegalInstruction(registerState(), &newPC)) {
+    set_pc(int64_t(newPC));
+    return;
+  }
+}
+
+// TODO(plind): consider making icount_ printing a flag option.
+template <typename T>
+void Simulator::TraceMemRd(sreg_t addr, T value, sreg_t reg_value) {
+  if (FLAG_trace_sim) {
+    if (std::is_integral<T>::value) {
+      switch (sizeof(T)) {
+        case 1:
+          SNPrintF(trace_buf_,
+                   "%016" REGIx_FORMAT "    (%" PRId64 ")    int8:%" PRId8
+                   " uint8:%" PRIu8 " <-- [addr: %" REGIx_FORMAT "]",
+                   reg_value, icount_, static_cast<int8_t>(value),
+                   static_cast<uint8_t>(value), addr);
+          break;
+        case 2:
+          SNPrintF(trace_buf_,
+                   "%016" REGIx_FORMAT "    (%" PRId64 ")    int16:%" PRId16
+                   " uint16:%" PRIu16 " <-- [addr: %" REGIx_FORMAT "]",
+                   reg_value, icount_, static_cast<int16_t>(value),
+                   static_cast<uint16_t>(value), addr);
+          break;
+        case 4:
+          SNPrintF(trace_buf_,
+                   "%016" REGIx_FORMAT "    (%" PRId64 ")    int32:%" PRId32
+                   " uint32:%" PRIu32 " <-- [addr: %" REGIx_FORMAT "]",
+                   reg_value, icount_, static_cast<int32_t>(value),
+                   static_cast<uint32_t>(value), addr);
+          break;
+        case 8:
+          SNPrintF(trace_buf_,
+                   "%016" REGIx_FORMAT "    (%" PRId64 ")    int64:%" PRId64
+                   " uint64:%" PRIu64 " <-- [addr: %" REGIx_FORMAT "]",
+                   reg_value, icount_, static_cast<int64_t>(value),
+                   static_cast<uint64_t>(value), addr);
+          break;
+        default:
+          UNREACHABLE();
+      }
+    } else if (std::is_same<float, T>::value) {
+      SNPrintF(trace_buf_,
+               "%016" REGIx_FORMAT "    (%" PRId64
+               ")    flt:%e <-- [addr: %" REGIx_FORMAT "]",
+               reg_value, icount_, static_cast<float>(value), addr);
+    } else if (std::is_same<double, T>::value) {
+      SNPrintF(trace_buf_,
+               "%016" REGIx_FORMAT "    (%" PRId64
+               ")    dbl:%e <-- [addr: %" REGIx_FORMAT "]",
+               reg_value, icount_, static_cast<double>(value), addr);
+    } else {
+      UNREACHABLE();
+    }
+  }
+}
+
+void Simulator::TraceMemRdFloat(sreg_t addr, Float32 value, int64_t reg_value) {
+  if (FLAG_trace_sim) {
+    SNPrintF(trace_buf_,
+             "%016" PRIx64 "    (%" PRId64
+             ")    flt:%e <-- [addr: %" REGIx_FORMAT "]",
+             reg_value, icount_, static_cast<float>(value.get_scalar()), addr);
+  }
+}
+
+void Simulator::TraceMemRdDouble(sreg_t addr, double value, int64_t reg_value) {
+  if (FLAG_trace_sim) {
+    SNPrintF(trace_buf_,
+             "%016" PRIx64 "    (%" PRId64
+             ")    dbl:%e <-- [addr: %" REGIx_FORMAT "]",
+             reg_value, icount_, static_cast<double>(value), addr);
+  }
+}
+
+void Simulator::TraceMemRdDouble(sreg_t addr, Float64 value,
+                                 int64_t reg_value) {
+  if (FLAG_trace_sim) {
+    SNPrintF(trace_buf_,
+             "%016" PRIx64 "    (%" PRId64
+             ")    dbl:%e <-- [addr: %" REGIx_FORMAT "]",
+             reg_value, icount_, static_cast<double>(value.get_scalar()), addr);
+  }
+}
+
+template <typename T>
+void Simulator::TraceMemWr(sreg_t addr, T value) {
+  if (FLAG_trace_sim) {
+    switch (sizeof(T)) {
+      case 1:
+        SNPrintF(trace_buf_,
+                 "                    (%" PRIu64 ")    int8:%" PRId8
+                 " uint8:%" PRIu8 " --> [addr: %" REGIx_FORMAT "]",
+                 icount_, static_cast<int8_t>(value),
+                 static_cast<uint8_t>(value), addr);
+        break;
+      case 2:
+        SNPrintF(trace_buf_,
+                 "                    (%" PRIu64 ")    int16:%" PRId16
+                 " uint16:%" PRIu16 " --> [addr: %" REGIx_FORMAT "]",
+                 icount_, static_cast<int16_t>(value),
+                 static_cast<uint16_t>(value), addr);
+        break;
+      case 4:
+        if (std::is_integral<T>::value) {
+          SNPrintF(trace_buf_,
+                   "                    (%" PRIu64 ")    int32:%" PRId32
+                   " uint32:%" PRIu32 " --> [addr: %" REGIx_FORMAT "]",
+                   icount_, static_cast<int32_t>(value),
+                   static_cast<uint32_t>(value), addr);
+        } else {
+          SNPrintF(trace_buf_,
+                   "                    (%" PRIu64
+                   ")    flt:%e --> [addr: %" REGIx_FORMAT "]",
+                   icount_, static_cast<float>(value), addr);
+        }
+        break;
+      case 8:
+        if (std::is_integral<T>::value) {
+          SNPrintF(trace_buf_,
+                   "                    (%" PRIu64 ")    int64:%" PRId64
+                   " uint64:%" PRIu64 " --> [addr: %" REGIx_FORMAT "]",
+                   icount_, static_cast<int64_t>(value),
+                   static_cast<uint64_t>(value), addr);
+        } else {
+          SNPrintF(trace_buf_,
+                   "                    (%" PRIu64
+                   ")    dbl:%e --> [addr: %" REGIx_FORMAT "]",
+                   icount_, static_cast<double>(value), addr);
+        }
+        break;
+      default:
+        UNREACHABLE();
+    }
+  }
+}
+
+void Simulator::TraceMemWrDouble(sreg_t addr, double value) {
+  if (FLAG_trace_sim) {
+    SNPrintF(trace_buf_,
+             "                    (%" PRIu64
+             ")    dbl:%e --> [addr: %" REGIx_FORMAT "]",
+             icount_, value, addr);
+  }
+}
+
+template <typename T>
+void Simulator::TraceLr(sreg_t addr, T value, sreg_t reg_value) {
+  if (FLAG_trace_sim) {
+    if (std::is_integral<T>::value) {
+      switch (sizeof(T)) {
+        case 4:
+          SNPrintF(trace_buf_,
+                   "%016" REGIx_FORMAT "    (%" PRId64 ")    int32:%" PRId32
+                   " uint32:%" PRIu32 " <-- [addr: %" REGIx_FORMAT "]",
+                   reg_value, icount_, static_cast<int32_t>(value),
+                   static_cast<uint32_t>(value), addr);
+          break;
+        case 8:
+          SNPrintF(trace_buf_,
+                   "%016" REGIx_FORMAT "    (%" PRId64 ")    int64:%" PRId64
+                   " uint64:%" PRIu64 " <-- [addr: %" REGIx_FORMAT "]",
+                   reg_value, icount_, static_cast<int64_t>(value),
+                   static_cast<uint64_t>(value), addr);
+          break;
+        default:
+          UNREACHABLE();
+      }
+    } else {
+      UNREACHABLE();
+    }
+  }
+}
+
+template <typename T>
+void Simulator::TraceSc(sreg_t addr, T value) {
+  if (FLAG_trace_sim) {
+    switch (sizeof(T)) {
+      case 4:
+        SNPrintF(trace_buf_,
+                 "%016" REGIx_FORMAT "    (%" PRIu64 ")    int32:%" PRId32
+                 " uint32:%" PRIu32 " --> [addr: %" REGIx_FORMAT "]",
+                 getRegister(rd_reg()), icount_, static_cast<int32_t>(value),
+                 static_cast<uint32_t>(value), addr);
+        break;
+      case 8:
+        SNPrintF(trace_buf_,
+                 "%016" REGIx_FORMAT "    (%" PRIu64 ")    int64:%" PRId64
+                 " uint64:%" PRIu64 " --> [addr: %" REGIx_FORMAT "]",
+                 getRegister(rd_reg()), icount_, static_cast<int64_t>(value),
+                 static_cast<uint64_t>(value), addr);
+        break;
+      default:
+        UNREACHABLE();
+    }
+  }
+}
+
+// TODO(RISCV): check whether the specific board supports unaligned load/store
+// (determined by EEI). For now, we assume the board does not support unaligned
+// load/store (e.g., trapping)
+template <typename T>
+T Simulator::ReadMem(sreg_t addr, Instruction* instr) {
+  if (handleWasmSegFault(addr, sizeof(T))) {
+    return -1;
+  }
+  if (addr >= 0 && addr < 0x400) {
+    // This has to be a nullptr-dereference, drop into debugger.
+    printf("Memory read from bad address: 0x%08" REGIx_FORMAT
+           " , pc=0x%08" PRIxPTR " \n",
+           addr, reinterpret_cast<intptr_t>(instr));
+    DieOrDebug();
+  }
+  T* ptr = reinterpret_cast<T*>(addr);
+  T value = *ptr;
+  return value;
+}
+
+template <typename T>
+void Simulator::WriteMem(sreg_t addr, T value, Instruction* instr) {
+  if (handleWasmSegFault(addr, sizeof(T))) {
+    value = -1;
+    return;
+  }
+  if (addr >= 0 && addr < 0x400) {
+    // This has to be a nullptr-dereference, drop into debugger.
+    printf("Memory write to bad address: 0x%08" REGIx_FORMAT
+           " , pc=0x%08" PRIxPTR " \n",
+           addr, reinterpret_cast<intptr_t>(instr));
+    DieOrDebug();
+  }
+  T* ptr = reinterpret_cast<T*>(addr);
+  if (!std::is_same<double, T>::value) {
+    TraceMemWr(addr, value);
+  } else {
+    TraceMemWrDouble(addr, value);
+  }
+  *ptr = value;
+}
+
+template <>
+void Simulator::WriteMem(sreg_t addr, Float32 value, Instruction* instr) {
+  if (handleWasmSegFault(addr, 4)) {
+    value = Float32(-1.0f);
+    return;
+  }
+  if (addr >= 0 && addr < 0x400) {
+    // This has to be a nullptr-dereference, drop into debugger.
+    printf("Memory write to bad address: 0x%08" REGIx_FORMAT
+           " , pc=0x%08" PRIxPTR " \n",
+           addr, reinterpret_cast<intptr_t>(instr));
+    DieOrDebug();
+  }
+  float* ptr = reinterpret_cast<float*>(addr);
+  TraceMemWr(addr, value.get_scalar());
+  memcpy(ptr, &value, 4);
+}
+
+template <>
+void Simulator::WriteMem(sreg_t addr, Float64 value, Instruction* instr) {
+  if (handleWasmSegFault(addr, 8)) {
+    value = Float64(-1.0);
+    return;
+  }
+  if (addr >= 0 && addr < 0x400) {
+    // This has to be a nullptr-dereference, drop into debugger.
+    printf("Memory write to bad address: 0x%08" REGIx_FORMAT
+           " , pc=0x%08" PRIxPTR " \n",
+           addr, reinterpret_cast<intptr_t>(instr));
+    DieOrDebug();
+  }
+  double* ptr = reinterpret_cast<double*>(addr);
+  TraceMemWrDouble(addr, value.get_scalar());
+  memcpy(ptr, &value, 8);
+}
+
+uintptr_t Simulator::stackLimit() const { return stackLimit_; }
+
+uintptr_t* Simulator::addressOfStackLimit() { return &stackLimit_; }
+
+bool Simulator::overRecursed(uintptr_t newsp) const {
+  if (newsp == 0) {
+    newsp = getRegister(sp);
+  }
+  return newsp <= stackLimit();
+}
+
+bool Simulator::overRecursedWithExtra(uint32_t extra) const {
+  uintptr_t newsp = getRegister(sp) - extra;
+  return newsp <= stackLimit();
+}
+
+// Unsupported instructions use format to print an error and stop execution.
+void Simulator::format(SimInstruction* instr, const char* format) {
+  printf("Simulator found unsupported instruction:\n 0x%016lx: %s\n",
+         reinterpret_cast<intptr_t>(instr), format);
+  MOZ_CRASH();
+}
+
+// Note: With the code below we assume that all runtime calls return a 64 bits
+// result. If they don't, the v1 result register contains a bogus value, which
+// is fine because it is caller-saved.
+typedef int64_t (*Prototype_General0)();
+typedef int64_t (*Prototype_General1)(int64_t arg0);
+typedef int64_t (*Prototype_General2)(int64_t arg0, int64_t arg1);
+typedef int64_t (*Prototype_General3)(int64_t arg0, int64_t arg1, int64_t arg2);
+typedef int64_t (*Prototype_General4)(int64_t arg0, int64_t arg1, int64_t arg2,
+                                      int64_t arg3);
+typedef int64_t (*Prototype_General5)(int64_t arg0, int64_t arg1, int64_t arg2,
+                                      int64_t arg3, int64_t arg4);
+typedef int64_t (*Prototype_General6)(int64_t arg0, int64_t arg1, int64_t arg2,
+                                      int64_t arg3, int64_t arg4, int64_t arg5);
+typedef int64_t (*Prototype_General7)(int64_t arg0, int64_t arg1, int64_t arg2,
+                                      int64_t arg3, int64_t arg4, int64_t arg5,
+                                      int64_t arg6);
+typedef int64_t (*Prototype_General8)(int64_t arg0, int64_t arg1, int64_t arg2,
+                                      int64_t arg3, int64_t arg4, int64_t arg5,
+                                      int64_t arg6, int64_t arg7);
+typedef int64_t (*Prototype_GeneralGeneralGeneralInt64)(int64_t arg0,
+                                                        int64_t arg1,
+                                                        int64_t arg2,
+                                                        int64_t arg3);
+typedef int64_t (*Prototype_GeneralGeneralInt64Int64)(int64_t arg0,
+                                                      int64_t arg1,
+                                                      int64_t arg2,
+                                                      int64_t arg3);
+
+typedef int64_t (*Prototype_Int_Double)(double arg0);
+typedef int64_t (*Prototype_Int_IntDouble)(int64_t arg0, double arg1);
+typedef int64_t (*Prototype_Int_DoubleInt)(double arg0, int64_t arg1);
+typedef int64_t (*Prototype_Int_DoubleIntInt)(double arg0, int64_t arg1,
+                                              int64_t arg2);
+typedef int64_t (*Prototype_Int_IntDoubleIntInt)(int64_t arg0, double arg1,
+                                                 int64_t arg2, int64_t arg3);
+
+typedef float (*Prototype_Float32_Float32)(float arg0);
+typedef int64_t (*Prototype_Int_Float32)(float arg0);
+typedef float (*Prototype_Float32_Float32Float32)(float arg0, float arg1);
+
+typedef double (*Prototype_Double_None)();
+typedef double (*Prototype_Double_Double)(double arg0);
+typedef double (*Prototype_Double_Int)(int64_t arg0);
+typedef double (*Prototype_Double_DoubleInt)(double arg0, int64_t arg1);
+typedef double (*Prototype_Double_IntDouble)(int64_t arg0, double arg1);
+typedef double (*Prototype_Double_DoubleDouble)(double arg0, double arg1);
+typedef double (*Prototype_Double_DoubleDoubleDouble)(double arg0, double arg1,
+                                                      double arg2);
+typedef double (*Prototype_Double_DoubleDoubleDoubleDouble)(double arg0,
+                                                            double arg1,
+                                                            double arg2,
+                                                            double arg3);
+
+typedef int32_t (*Prototype_Int32_General)(int64_t);
+typedef int32_t (*Prototype_Int32_GeneralInt32)(int64_t, int32_t);
+typedef int32_t (*Prototype_Int32_GeneralInt32Int32)(int64_t, int32_t, int32_t);
+typedef int32_t (*Prototype_Int32_GeneralInt32Int32Int32)(int64_t, int32_t,
+                                                          int32_t, int32_t);
+typedef int32_t (*Prototype_Int32_GeneralInt32Int32Int32Int32)(int64_t, int32_t,
+                                                               int32_t, int32_t,
+                                                               int32_t);
+typedef int32_t (*Prototype_Int32_GeneralInt32Int32Int32Int32Int32)(
+    int64_t, int32_t, int32_t, int32_t, int32_t, int32_t);
+typedef int32_t (*Prototype_Int32_GeneralInt32Int32Int32Int32General)(
+    int64_t, int32_t, int32_t, int32_t, int32_t, int64_t);
+typedef int32_t (*Prototype_Int32_GeneralInt32Int32Int32General)(
+    int64_t, int32_t, int32_t, int32_t, int64_t);
+typedef int32_t (*Prototype_Int32_GeneralInt32Int32General)(int64_t, int32_t,
+                                                            int32_t, int64_t);
+typedef int32_t (*Prototype_Int32_GeneralInt32Int32Int64Int32)(int64_t, int32_t,
+                                                               int32_t, int64_t,
+                                                               int32_t);
+typedef int32_t (*Prototype_Int32_GeneralInt32GeneralInt32)(int64_t, int32_t,
+                                                            int64_t, int32_t);
+typedef int32_t (*Prototype_Int32_GeneralInt32GeneralInt32Int32)(
+    int64_t, int32_t, int64_t, int32_t, int32_t);
+typedef int32_t (*Prototype_Int32_GeneralInt32Int64Int64Int32)(int64_t, int32_t,
+                                                               int64_t, int64_t,
+                                                               int32_t);
+typedef int32_t (*Prototype_Int32_GeneralGeneral)(int64_t, int64_t);
+typedef int32_t (*Prototype_Int32_GeneralGeneralGeneral)(int64_t, int64_t,
+                                                         int64_t);
+typedef int32_t (*Prototype_Int32_GeneralGeneralInt32Int32)(int64_t, int64_t,
+                                                            int32_t, int32_t);
+typedef int32_t (*Prototype_Int32_GeneralInt64Int32Int32)(int64_t, int64_t,
+                                                          int32_t, int32_t);
+typedef int32_t (*Prototype_Int32_GeneralInt64Int32Int32Int32Int32)(
+    int64_t, int64_t, int32_t, int32_t, int32_t, int32_t);
+typedef int32_t (*Prototype_Int32_GeneralInt64Int32Int64Int32)(int64_t, int64_t,
+                                                               int32_t, int64_t,
+                                                               int32_t);
+typedef int32_t (*Prototype_Int32_GeneralInt64Int32Int32Int32)(int64_t, int64_t,
+                                                               int32_t, int32_t,
+                                                               int32_t);
+typedef int32_t (*Prototype_Int32_GeneralGeneralInt32Int32Int32GeneralInt32)(
+    int64_t, int64_t, int32_t, int32_t, int32_t, int64_t, int32_t);
+typedef int32_t (*Prototype_Int32_GeneralGeneralInt32General)(int32_t, int32_t,
+                                                              int32_t, int32_t);
+typedef int32_t (*Prototype_Int32_GeneralInt64Int32Int64General)(
+    int64_t, int64_t, int32_t, int64_t, int64_t);
+typedef int32_t (*Prototype_Int32_GeneralInt64Int64Int64)(int64_t, int64_t,
+                                                          int64_t, int64_t);
+typedef int32_t (*Prototype_Int32_GeneralInt64Int64Int64Int32)(int64_t, int64_t,
+                                                               int64_t, int64_t,
+                                                               int32_t);
+typedef int32_t (*Prototype_Int32_GeneralInt64Int64General)(int64_t, int64_t,
+                                                            int64_t, int64_t);
+typedef int32_t (*Prototype_Int32_GeneralInt64Int64Int64General)(
+    int64_t, int64_t, int64_t, int64_t, int64_t);
+typedef int32_t (*Prototype_Int32_GeneralInt64Int64Int64Int32Int32)(
+    int64_t, int64_t, int64_t, int64_t, int32_t, int32_t);
+typedef int64_t (*Prototype_General_GeneralInt32)(int64_t, int32_t);
+typedef int64_t (*Prototype_General_GeneralInt32Int32)(int64_t, int32_t,
+                                                       int32_t);
+typedef int64_t (*Prototype_General_GeneralInt32General)(int64_t, int32_t,
+                                                         int64_t);
+typedef int64_t (*Prototype_General_GeneralInt32Int32GeneralInt32)(
+    int64_t, int32_t, int32_t, int64_t, int32_t);
+typedef int32_t (*Prototype_Int32_GeneralGeneralInt32GeneralInt32Int32Int32)(
+    int64_t, int64_t, int32_t, int64_t, int32_t, int32_t, int32_t);
+typedef int64_t (*Prototype_Int64_General)(int64_t);
+typedef int64_t (*Prototype_Int64_GeneralInt32)(int64_t, int32_t);
+typedef int64_t (*Prototype_Int64_GeneralInt64)(int64_t, int64_t);
+typedef int64_t (*Prototype_Int64_GeneralInt64Int32)(int64_t, int64_t, int32_t);
+typedef int32_t (*Prototype_Int32_GeneralInt64Int64General)(int64_t, int64_t,
+                                                            int64_t, int64_t);
+// Generated by Assembler::break_()/stop(), ebreak code is passed as immediate
+// field of a subsequent LUI instruction; otherwise returns -1
+static inline uint32_t get_ebreak_code(Instruction* instr) {
+  MOZ_ASSERT(instr->InstructionBits() == kBreakInstr);
+  uint8_t* cur = reinterpret_cast<uint8_t*>(instr);
+  Instruction* next_instr = reinterpret_cast<Instruction*>(cur + kInstrSize);
+  if (next_instr->BaseOpcodeFieldRaw() == LUI)
+    return (next_instr->Imm20UValue());
+  else
+    return -1;
+}
+
+// Software interrupt instructions are used by the simulator to call into C++.
+void Simulator::SoftwareInterrupt() {
+  // There are two instructions that could get us here, the ebreak or ecall
+  // instructions are "SYSTEM" class opcode distinuished by Imm12Value field w/
+  // the rest of instruction fields being zero
+  // We first check if we met a call_rt_redirected.
+  if (instr_.InstructionBits() == rtCallRedirInstr) {
+    Redirection* redirection = Redirection::FromSwiInstruction(instr_.instr());
+    uintptr_t nativeFn =
+        reinterpret_cast<uintptr_t>(redirection->nativeFunction());
+
+    intptr_t arg0 = getRegister(a0);
+    intptr_t arg1 = getRegister(a1);
+    intptr_t arg2 = getRegister(a2);
+    intptr_t arg3 = getRegister(a3);
+    intptr_t arg4 = getRegister(a4);
+    intptr_t arg5 = getRegister(a5);
+    intptr_t arg6 = getRegister(a6);
+    intptr_t arg7 = getRegister(a7);
+
+    // This is dodgy but it works because the C entry stubs are never moved.
+    // See comment in codegen-arm.cc and bug 1242173.
+    intptr_t saved_ra = getRegister(ra);
+
+    intptr_t external =
+        reinterpret_cast<intptr_t>(redirection->nativeFunction());
+
+    bool stack_aligned = (getRegister(sp) & (ABIStackAlignment - 1)) == 0;
+    if (!stack_aligned) {
+      fprintf(stderr, "Runtime call with unaligned stack!\n");
+      MOZ_CRASH();
+    }
+
+    if (single_stepping_) {
+      single_step_callback_(single_step_callback_arg_, this, nullptr);
+    }
+    if (FLAG_trace_sim) {
+      printf(
+          "Call to host function at %p with args %ld, %ld, %ld, %ld, %ld, %ld, "
+          "%ld, %ld\n",
+          reinterpret_cast<void*>(external), arg0, arg1, arg2, arg3, arg4, arg5,
+          arg6, arg7);
+    }
+    switch (redirection->type()) {
+      case Args_General0: {
+        Prototype_General0 target =
+            reinterpret_cast<Prototype_General0>(external);
+        int64_t result = target();
+        if (FLAG_trace_sim) printf("ret %ld\n", result);
+        setCallResult(result);
+        break;
+      }
+      case Args_General1: {
+        Prototype_General1 target =
+            reinterpret_cast<Prototype_General1>(external);
+        int64_t result = target(arg0);
+        if (FLAG_trace_sim) printf("ret %ld\n", result);
+        setCallResult(result);
+        break;
+      }
+      case Args_General2: {
+        Prototype_General2 target =
+            reinterpret_cast<Prototype_General2>(external);
+        int64_t result = target(arg0, arg1);
+        if (FLAG_trace_sim) printf("ret %ld\n", result);
+        setCallResult(result);
+        break;
+      }
+      case Args_General3: {
+        Prototype_General3 target =
+            reinterpret_cast<Prototype_General3>(external);
+        int64_t result = target(arg0, arg1, arg2);
+        if (FLAG_trace_sim) printf("ret %ld\n", result);
+        if (external == intptr_t(&js::wasm::Instance::wake_m32)) {
+          result = int32_t(result);
+        }
+        setCallResult(result);
+        break;
+      }
+      case Args_General4: {
+        Prototype_General4 target =
+            reinterpret_cast<Prototype_General4>(external);
+        int64_t result = target(arg0, arg1, arg2, arg3);
+        if (FLAG_trace_sim) printf("ret %ld\n", result);
+        setCallResult(result);
+        break;
+      }
+      case Args_General5: {
+        Prototype_General5 target =
+            reinterpret_cast<Prototype_General5>(external);
+        int64_t result = target(arg0, arg1, arg2, arg3, arg4);
+        if (FLAG_trace_sim) printf("ret %ld\n", result);
+        setCallResult(result);
+        break;
+      }
+      case Args_General6: {
+        Prototype_General6 target =
+            reinterpret_cast<Prototype_General6>(external);
+        int64_t result = target(arg0, arg1, arg2, arg3, arg4, arg5);
+        if (FLAG_trace_sim) printf("ret %ld\n", result);
+        setCallResult(result);
+        break;
+      }
+      case Args_General7: {
+        Prototype_General7 target =
+            reinterpret_cast<Prototype_General7>(external);
+        int64_t result = target(arg0, arg1, arg2, arg3, arg4, arg5, arg6);
+        if (FLAG_trace_sim) printf("ret %ld\n", result);
+        setCallResult(result);
+        break;
+      }
+      case Args_General8: {
+        Prototype_General8 target =
+            reinterpret_cast<Prototype_General8>(external);
+        int64_t result = target(arg0, arg1, arg2, arg3, arg4, arg5, arg6, arg7);
+        if (FLAG_trace_sim) printf("ret %ld\n", result);
+        setCallResult(result);
+        break;
+      }
+      case Args_Double_None: {
+        Prototype_Double_None target =
+            reinterpret_cast<Prototype_Double_None>(external);
+        double dresult = target();
+        if (FLAG_trace_sim) printf("ret %f\n", dresult);
+        setCallResultDouble(dresult);
+        break;
+      }
+      case Args_Int_Double: {
+        double dval0 = getFpuRegisterDouble(fa0);
+        Prototype_Int_Double target =
+            reinterpret_cast<Prototype_Int_Double>(external);
+        int64_t result = target(dval0);
+        if (FLAG_trace_sim) printf("ret %ld\n", result);
+        if (external == intptr_t((int32_t(*)(double))JS::ToInt32)) {
+          result = int32_t(result);
+        }
+        setRegister(a0, result);
+        break;
+      }
+      case Args_Int_GeneralGeneralGeneralInt64: {
+        Prototype_GeneralGeneralGeneralInt64 target =
+            reinterpret_cast<Prototype_GeneralGeneralGeneralInt64>(external);
+        int64_t result = target(arg0, arg1, arg2, arg3);
+        if (FLAG_trace_sim) printf("ret %ld\n", result);
+        if (external == intptr_t(&js::wasm::Instance::wait_i32_m32)) {
+          result = int32_t(result);
+        }
+        setRegister(a0, result);
+        break;
+      }
+      case Args_Int_GeneralGeneralInt64Int64: {
+        Prototype_GeneralGeneralInt64Int64 target =
+            reinterpret_cast<Prototype_GeneralGeneralInt64Int64>(external);
+        int64_t result = target(arg0, arg1, arg2, arg3);
+        if (FLAG_trace_sim) printf("ret %ld\n", result);
+        if (external == intptr_t(&js::wasm::Instance::wait_i64_m32)) {
+          result = int32_t(result);
+        }
+        setRegister(a0, result);
+        break;
+      }
+      case Args_Int_DoubleInt: {
+        double dval = getFpuRegisterDouble(fa0);
+        Prototype_Int_DoubleInt target =
+            reinterpret_cast<Prototype_Int_DoubleInt>(external);
+        int64_t result = target(dval, arg0);
+        if (FLAG_trace_sim) printf("ret %ld\n", result);
+        setRegister(a0, result);
+        break;
+      }
+      case Args_Int_DoubleIntInt: {
+        double dval = getFpuRegisterDouble(fa0);
+        Prototype_Int_DoubleIntInt target =
+            reinterpret_cast<Prototype_Int_DoubleIntInt>(external);
+        int64_t result = target(dval, arg1, arg2);
+        if (FLAG_trace_sim) printf("ret %ld\n", result);
+        setRegister(a0, result);
+        break;
+      }
+      case Args_Int_IntDoubleIntInt: {
+        double dval = getFpuRegisterDouble(fa0);
+        Prototype_Int_IntDoubleIntInt target =
+            reinterpret_cast<Prototype_Int_IntDoubleIntInt>(external);
+        int64_t result = target(arg0, dval, arg2, arg3);
+        if (FLAG_trace_sim) printf("ret %ld\n", result);
+        setRegister(a0, result);
+        break;
+      }
+      case Args_Double_Double: {
+        double dval0 = getFpuRegisterDouble(fa0);
+        Prototype_Double_Double target =
+            reinterpret_cast<Prototype_Double_Double>(external);
+        double dresult = target(dval0);
+        if (FLAG_trace_sim) printf("ret %f\n", dresult);
+        setCallResultDouble(dresult);
+        break;
+      }
+      case Args_Float32_Float32: {
+        float fval0;
+        fval0 = getFpuRegisterFloat(fa0);
+        Prototype_Float32_Float32 target =
+            reinterpret_cast<Prototype_Float32_Float32>(external);
+        float fresult = target(fval0);
+        if (FLAG_trace_sim) printf("ret %f\n", fresult);
+        setCallResultFloat(fresult);
+        break;
+      }
+      case Args_Int_Float32: {
+        float fval0;
+        fval0 = getFpuRegisterFloat(fa0);
+        Prototype_Int_Float32 target =
+            reinterpret_cast<Prototype_Int_Float32>(external);
+        int64_t result = target(fval0);
+        if (FLAG_trace_sim) printf("ret %ld\n", result);
+        setRegister(a0, result);
+        break;
+      }
+      case Args_Float32_Float32Float32: {
+        float fval0;
+        float fval1;
+        fval0 = getFpuRegisterFloat(fa0);
+        fval1 = getFpuRegisterFloat(fa1);
+        Prototype_Float32_Float32Float32 target =
+            reinterpret_cast<Prototype_Float32_Float32Float32>(external);
+        float fresult = target(fval0, fval1);
+        if (FLAG_trace_sim) printf("ret %f\n", fresult);
+        setCallResultFloat(fresult);
+        break;
+      }
+      case Args_Double_Int: {
+        Prototype_Double_Int target =
+            reinterpret_cast<Prototype_Double_Int>(external);
+        double dresult = target(arg0);
+        if (FLAG_trace_sim) printf("ret %f\n", dresult);
+        setCallResultDouble(dresult);
+        break;
+      }
+      case Args_Double_DoubleInt: {
+        double dval0 = getFpuRegisterDouble(fa0);
+        Prototype_Double_DoubleInt target =
+            reinterpret_cast<Prototype_Double_DoubleInt>(external);
+        double dresult = target(dval0, arg0);
+        if (FLAG_trace_sim) printf("ret %f\n", dresult);
+        setCallResultDouble(dresult);
+        break;
+      }
+      case Args_Double_DoubleDouble: {
+        double dval0 = getFpuRegisterDouble(fa0);
+        double dval1 = getFpuRegisterDouble(fa1);
+        Prototype_Double_DoubleDouble target =
+            reinterpret_cast<Prototype_Double_DoubleDouble>(external);
+        double dresult = target(dval0, dval1);
+        if (FLAG_trace_sim) printf("ret %f\n", dresult);
+        setCallResultDouble(dresult);
+        break;
+      }
+      case Args_Double_IntDouble: {
+        double dval0 = getFpuRegisterDouble(fa0);
+        Prototype_Double_IntDouble target =
+            reinterpret_cast<Prototype_Double_IntDouble>(external);
+        double dresult = target(arg0, dval0);
+        if (FLAG_trace_sim) printf("ret %f\n", dresult);
+        setCallResultDouble(dresult);
+        break;
+      }
+      case Args_Int_IntDouble: {
+        double dval0 = getFpuRegisterDouble(fa0);
+        Prototype_Int_IntDouble target =
+            reinterpret_cast<Prototype_Int_IntDouble>(external);
+        int64_t result = target(arg0, dval0);
+        if (FLAG_trace_sim) printf("ret %ld\n", result);
+        setRegister(a0, result);
+        break;
+      }
+      case Args_Double_DoubleDoubleDouble: {
+        double dval0 = getFpuRegisterDouble(fa0);
+        double dval1 = getFpuRegisterDouble(fa1);
+        double dval2 = getFpuRegisterDouble(fa2);
+        Prototype_Double_DoubleDoubleDouble target =
+            reinterpret_cast<Prototype_Double_DoubleDoubleDouble>(external);
+        double dresult = target(dval0, dval1, dval2);
+        if (FLAG_trace_sim) printf("ret %f\n", dresult);
+        setCallResultDouble(dresult);
+        break;
+      }
+      case Args_Double_DoubleDoubleDoubleDouble: {
+        double dval0 = getFpuRegisterDouble(fa0);
+        double dval1 = getFpuRegisterDouble(fa1);
+        double dval2 = getFpuRegisterDouble(fa2);
+        double dval3 = getFpuRegisterDouble(fa3);
+        Prototype_Double_DoubleDoubleDoubleDouble target =
+            reinterpret_cast<Prototype_Double_DoubleDoubleDoubleDouble>(
+                external);
+        double dresult = target(dval0, dval1, dval2, dval3);
+        if (FLAG_trace_sim) printf("ret %f\n", dresult);
+        setCallResultDouble(dresult);
+        break;
+      }
+      case Args_Int32_General: {
+        int32_t ret = reinterpret_cast<Prototype_Int32_General>(nativeFn)(arg0);
+        if (FLAG_trace_sim) printf("ret %d\n", ret);
+        setRegister(a0, I64(ret));
+        break;
+      }
+      case Args_Int32_GeneralInt32: {
+        int32_t ret = reinterpret_cast<Prototype_Int32_GeneralInt32>(nativeFn)(
+            arg0, I32(arg1));
+        if (FLAG_trace_sim) printf("ret %d\n", ret);
+        setRegister(a0, I64(ret));
+        break;
+      }
+      case Args_Int32_GeneralInt32Int32: {
+        int32_t ret = reinterpret_cast<Prototype_Int32_GeneralInt32Int32>(
+            nativeFn)(arg0, I32(arg1), I32(arg2));
+        if (FLAG_trace_sim) printf("ret %d\n", ret);
+        setRegister(a0, I64(ret));
+        break;
+      }
+      case Args_Int32_GeneralInt32Int32Int32: {
+        int32_t ret = reinterpret_cast<Prototype_Int32_GeneralInt32Int32Int32>(
+            nativeFn)(arg0, I32(arg1), I32(arg2), I32(arg3));
+        setRegister(a0, I64(ret));
+        break;
+      }
+      case Args_Int32_GeneralInt32Int32Int32Int32: {
+        int32_t ret =
+            reinterpret_cast<Prototype_Int32_GeneralInt32Int32Int32Int32>(
+                nativeFn)(arg0, I32(arg1), I32(arg2), I32(arg3), I32(arg4));
+        if (FLAG_trace_sim) printf("ret %d\n", ret);
+        setRegister(a0, I64(ret));
+        break;
+      }
+      case Args_Int32_GeneralInt32Int32Int32Int32Int32: {
+        int32_t ret =
+            reinterpret_cast<Prototype_Int32_GeneralInt32Int32Int32Int32Int32>(
+                nativeFn)(arg0, I32(arg1), I32(arg2), I32(arg3), I32(arg4),
+                          I32(arg5));
+        if (FLAG_trace_sim) printf("ret %d\n", ret);
+        setRegister(a0, I64(ret));
+        break;
+      }
+      case Args_Int32_GeneralInt32Int32Int32Int32General: {
+        int32_t ret = reinterpret_cast<
+            Prototype_Int32_GeneralInt32Int32Int32Int32General>(nativeFn)(
+            arg0, I32(arg1), I32(arg2), I32(arg3), I32(arg4), arg5);
+        if (FLAG_trace_sim) printf("ret %d\n", ret);
+        setRegister(a0, I64(ret));
+        break;
+      }
+      case Args_Int32_GeneralInt32Int32Int32General: {
+        int32_t ret =
+            reinterpret_cast<Prototype_Int32_GeneralInt32Int32Int32General>(
+                nativeFn)(arg0, I32(arg1), I32(arg2), I32(arg3), arg4);
+        if (FLAG_trace_sim) printf("ret %d\n", ret);
+        setRegister(a0, I64(ret));
+        break;
+      }
+      case Args_Int32_GeneralInt32Int32General: {
+        int32_t ret =
+            reinterpret_cast<Prototype_Int32_GeneralInt32Int32General>(
+                nativeFn)(arg0, I32(arg1), I32(arg2), arg3);
+        if (FLAG_trace_sim) printf("ret %d\n", ret);
+        setRegister(a0, I64(ret));
+        break;
+      }
+      case Args_Int32_GeneralInt32Int32Int64Int32: {
+        int32_t ret =
+            reinterpret_cast<Prototype_Int32_GeneralInt32Int32Int64Int32>(
+                nativeFn)(arg0, I32(arg1), I32(arg2), arg3, I32(arg4));
+        setRegister(a0, I64(ret));
+        break;
+      }
+      case Args_Int32_GeneralInt32GeneralInt32: {
+        int32_t ret =
+            reinterpret_cast<Prototype_Int32_GeneralInt32GeneralInt32>(
+                nativeFn)(arg0, I32(arg1), arg2, I32(arg3));
+        if (FLAG_trace_sim) printf("ret %d\n", ret);
+        setRegister(a0, I64(ret));
+        break;
+      }
+      case Args_Int32_GeneralInt32GeneralInt32Int32: {
+        int32_t ret =
+            reinterpret_cast<Prototype_Int32_GeneralInt32GeneralInt32Int32>(
+                nativeFn)(arg0, I32(arg1), arg2, I32(arg3), I32(arg4));
+        if (FLAG_trace_sim) printf("ret %d\n", ret);
+        setRegister(a0, I64(ret));
+        break;
+      }
+      case Args_Int32_GeneralGeneral: {
+        int32_t ret = reinterpret_cast<Prototype_Int32_GeneralGeneral>(
+            nativeFn)(arg0, arg1);
+        if (FLAG_trace_sim) printf("ret %d\n", ret);
+        setRegister(a0, I64(ret));
+        break;
+      }
+      case Args_Int32_GeneralInt32Int64Int64Int32: {
+        int32_t ret =
+            reinterpret_cast<Prototype_Int32_GeneralInt32Int64Int64Int32>(
+                nativeFn)(arg0, I32(arg1), arg2, arg3, I32(arg4));
+        setRegister(a0, I64(ret));
+        break;
+      }
+      case Args_Int32_GeneralGeneralGeneral: {
+        int32_t ret = reinterpret_cast<Prototype_Int32_GeneralGeneralGeneral>(
+            nativeFn)(arg0, arg1, arg2);
+        if (FLAG_trace_sim) printf("ret %d\n", ret);
+        setRegister(a0, I64(ret));
+        break;
+      }
+      case Args_Int32_GeneralGeneralInt32Int32: {
+        int32_t ret =
+            reinterpret_cast<Prototype_Int32_GeneralGeneralInt32Int32>(
+                nativeFn)(arg0, arg1, I32(arg2), I32(arg3));
+        if (FLAG_trace_sim) printf("ret %d\n", ret);
+        setRegister(a0, I64(ret));
+        break;
+      }
+      case js::jit::Args_Int32_GeneralInt64Int32Int32: {
+        int32_t ret = reinterpret_cast<Prototype_Int32_GeneralInt64Int32Int32>(
+            nativeFn)(arg0, arg1, I32(arg2), I32(arg3));
+        setRegister(a0, I64(ret));
+        break;
+      }
+      case js::jit::Args_Int32_GeneralInt64Int32Int32Int32Int32: {
+        int32_t ret =
+            reinterpret_cast<Prototype_Int32_GeneralInt64Int32Int32Int32Int32>(
+                nativeFn)(arg0, arg1, I32(arg2), I32(arg3), I32(arg4),
+                          I32(arg5));
+        setRegister(a0, I64(ret));
+        break;
+      }
+      case js::jit::Args_Int32_GeneralInt64Int32Int64Int32: {
+        int32_t ret =
+            reinterpret_cast<Prototype_Int32_GeneralInt64Int32Int64Int32>(
+                nativeFn)(arg0, arg1, I32(arg2), arg3, I32(arg4));
+        setRegister(a0, I64(ret));
+        break;
+      }
+      case js::jit::Args_Int32_GeneralInt64Int32Int64General: {
+        int32_t ret =
+            reinterpret_cast<Prototype_Int32_GeneralInt64Int32Int64General>(
+                nativeFn)(arg0, arg1, I32(arg2), arg3, arg4);
+        if (FLAG_trace_sim) printf("ret %d\n", ret);
+        setRegister(a0, I64(ret));
+        break;
+      }
+      case js::jit::Args_Int32_GeneralInt64Int64Int64: {
+        int32_t ret = reinterpret_cast<Prototype_Int32_GeneralInt64Int64Int64>(
+            nativeFn)(arg0, arg1, arg2, arg3);
+        if (FLAG_trace_sim) printf("ret %d\n", ret);
+        setRegister(a0, I64(ret));
+        break;
+      }
+      case js::jit::Args_Int32_GeneralInt64Int64Int64Int32: {
+        int32_t ret =
+            reinterpret_cast<Prototype_Int32_GeneralInt64Int64Int64Int32>(
+                nativeFn)(arg0, arg1, arg2, arg3, I32(arg4));
+        setRegister(a0, I64(ret));
+        break;
+      }
+      case js::jit::Args_Int32_GeneralInt64Int64General: {
+        int32_t ret =
+            reinterpret_cast<Prototype_Int32_GeneralInt64Int64General>(
+                nativeFn)(arg0, arg1, arg2, arg3);
+        if (FLAG_trace_sim) printf("ret %d\n", ret);
+        setRegister(a0, I64(ret));
+        break;
+      }
+      case js::jit::Args_Int32_GeneralInt64Int64Int64General: {
+        int32_t ret =
+            reinterpret_cast<Prototype_Int32_GeneralInt64Int64Int64General>(
+                nativeFn)(arg0, arg1, arg2, arg3, arg4);
+        if (FLAG_trace_sim) printf("ret %d\n", ret);
+        setRegister(a0, I64(ret));
+        break;
+      }
+      case Args_General_GeneralInt32: {
+        int64_t ret = reinterpret_cast<Prototype_General_GeneralInt32>(
+            nativeFn)(arg0, I32(arg1));
+        if (FLAG_trace_sim) printf("ret %ld\n", ret);
+        setRegister(a0, ret);
+        break;
+      }
+      case js::jit::Args_Int32_GeneralInt64Int64Int64Int32Int32: {
+        int32_t ret =
+            reinterpret_cast<Prototype_Int32_GeneralInt64Int64Int64Int32Int32>(
+                nativeFn)(arg0, arg1, arg2, arg3, I32(arg4), I32(arg5));
+        setRegister(a0, I64(ret));
+        break;
+      }
+      case Args_General_GeneralInt32Int32: {
+        int64_t ret = reinterpret_cast<Prototype_General_GeneralInt32Int32>(
+            nativeFn)(arg0, I32(arg1), I32(arg2));
+        if (FLAG_trace_sim) printf("ret %ld\n", ret);
+        setRegister(a0, ret);
+        break;
+      }
+      case Args_General_GeneralInt32General: {
+        int64_t ret = reinterpret_cast<Prototype_General_GeneralInt32General>(
+            nativeFn)(arg0, I32(arg1), arg2);
+        if (FLAG_trace_sim) printf("ret %ld\n", ret);
+        setRegister(a0, ret);
+        break;
+      }
+      case js::jit::Args_General_GeneralInt32Int32GeneralInt32: {
+        int64_t ret =
+            reinterpret_cast<Prototype_General_GeneralInt32Int32GeneralInt32>(
+                nativeFn)(arg0, I32(arg1), I32(arg2), arg3, I32(arg4));
+        setRegister(a0, ret);
+        break;
+      }
+      case js::jit::Args_Int32_GeneralGeneralInt32Int32Int32GeneralInt32: {
+        int32_t ret = reinterpret_cast<
+            Prototype_Int32_GeneralGeneralInt32Int32Int32GeneralInt32>(
+            nativeFn)(arg0, arg1, I32(arg2), I32(arg3), I32(arg4), arg5,
+                      I32(arg6));
+        setRegister(a0, I64(ret));
+        break;
+      }
+      case js::jit::Args_Int32_GeneralGeneralInt32General: {
+        Prototype_Int32_GeneralGeneralInt32General target =
+            reinterpret_cast<Prototype_Int32_GeneralGeneralInt32General>(
+                external);
+        int64_t result = target(I32(arg0), I32(arg1), I32(arg2), I32(arg3));
+        setRegister(a0, I64(result));
+        break;
+      }
+      case js::jit::Args_Int32_GeneralGeneralInt32GeneralInt32Int32Int32: {
+        int64_t arg6 = getRegister(a6);
+        int32_t ret = reinterpret_cast<
+            Prototype_Int32_GeneralGeneralInt32GeneralInt32Int32Int32>(
+            nativeFn)(arg0, arg1, I32(arg2), arg3, I32(arg4), I32(arg5),
+                      I32(arg6));
+        setRegister(a0, I64(ret));
+        break;
+      }
+      case js::jit::Args_Int64_General: {
+        int64_t ret = reinterpret_cast<Prototype_Int64_General>(nativeFn)(arg0);
+        if (FLAG_trace_sim) printf("ret %ld\n", ret);
+        setRegister(a0, ret);
+        break;
+      }
+      case js::jit::Args_Int64_GeneralInt32: {
+        int64_t ret = reinterpret_cast<Prototype_Int64_GeneralInt32>(nativeFn)(
+            arg0, I32(arg1));
+        setRegister(a0, ret);
+        break;
+      }
+      case js::jit::Args_Int64_GeneralInt64: {
+        int64_t ret = reinterpret_cast<Prototype_Int64_GeneralInt64>(nativeFn)(
+            arg0, arg1);
+        setRegister(a0, ret);
+        break;
+      }
+      case js::jit::Args_Int64_GeneralInt64Int32: {
+        int64_t ret = reinterpret_cast<Prototype_Int64_GeneralInt64Int32>(
+            nativeFn)(arg0, arg1, I32(arg2));
+        setRegister(a0, ret);
+        break;
+      }
+      default:
+        MOZ_CRASH("Unknown function type.");
+    }
+
+    if (single_stepping_) {
+      single_step_callback_(single_step_callback_arg_, this, nullptr);
+    }
+
+    setRegister(ra, saved_ra);
+    set_pc(getRegister(ra));
+
+  } else if (instr_.InstructionBits() == kBreakInstr &&
+             (get_ebreak_code(instr_.instr()) <= kMaxStopCode)) {
+    uint32_t code = get_ebreak_code(instr_.instr());
+    if (isWatchpoint(code)) {
+      printWatchpoint(code);
+    } else if (IsTracepoint(code)) {
+      if (!FLAG_debug_sim) {
+        MOZ_CRASH("Add --debug-sim when tracepoint instruction is used.\n");
+      }
+      // printf("%d %d %d %d %d %d %d\n", code, code & LOG_TRACE, code &
+      // LOG_REGS,
+      //        code & kDebuggerTracingDirectivesMask, TRACE_ENABLE,
+      //        TRACE_DISABLE, kDebuggerTracingDirectivesMask);
+      switch (code & kDebuggerTracingDirectivesMask) {
+        case TRACE_ENABLE:
+          if (code & LOG_TRACE) {
+            FLAG_trace_sim = true;
+          }
+          if (code & LOG_REGS) {
+            RiscvDebugger dbg(this);
+            dbg.printAllRegs();
+          }
+          break;
+        case TRACE_DISABLE:
+          if (code & LOG_TRACE) {
+            FLAG_trace_sim = false;
+          }
+          break;
+        default:
+          UNREACHABLE();
+      }
+    } else {
+      increaseStopCounter(code);
+      handleStop(code);
+    }
+  } else {
+    //     uint8_t code = get_ebreak_code(instr_.instr()) - kMaxStopCode - 1;
+    //     switch (LNode::Opcode(code)) {
+    // #define EMIT_OP(OP, ...)  \
+//       case LNode::Opcode::OP:\
+//            std::cout << #OP << std::endl; \
+//            break;
+    //     LIR_OPCODE_LIST(EMIT_OP);
+    // #undef EMIT_OP
+    //     }
+    DieOrDebug();
+  }
+}
+
+// Stop helper functions.
+bool Simulator::isWatchpoint(uint32_t code) {
+  return (code <= kMaxWatchpointCode);
+}
+
+bool Simulator::IsTracepoint(uint32_t code) {
+  return (code <= kMaxTracepointCode && code > kMaxWatchpointCode);
+}
+
+void Simulator::printWatchpoint(uint32_t code) {
+  RiscvDebugger dbg(this);
+  ++break_count_;
+  if (FLAG_riscv_print_watchpoint) {
+    printf("\n---- break %d marker: %20" PRIi64 "  (instr count: %20" PRIi64
+           ") ----\n",
+           code, break_count_, icount_);
+    dbg.printAllRegs();  // Print registers and continue running.
+  }
+}
+
+void Simulator::handleStop(uint32_t code) {
+  // Stop if it is enabled, otherwise go on jumping over the stop
+  // and the message address.
+  if (isEnabledStop(code)) {
+    RiscvDebugger dbg(this);
+    dbg.Debug();
+  } else {
+    set_pc(get_pc() + 2 * kInstrSize);
+  }
+}
+
+bool Simulator::isStopInstruction(SimInstruction* instr) {
+  if (instr->InstructionBits() != kBreakInstr) return false;
+  int32_t code = get_ebreak_code(instr->instr());
+  return code != -1 && static_cast<uint32_t>(code) > kMaxWatchpointCode &&
+         static_cast<uint32_t>(code) <= kMaxStopCode;
+}
+
+bool Simulator::isEnabledStop(uint32_t code) {
+  MOZ_ASSERT(code <= kMaxStopCode);
+  MOZ_ASSERT(code > kMaxWatchpointCode);
+  return !(watchedStops_[code].count_ & kStopDisabledBit);
+}
+
+void Simulator::enableStop(uint32_t code) {
+  if (!isEnabledStop(code)) {
+    watchedStops_[code].count_ &= ~kStopDisabledBit;
+  }
+}
+
+void Simulator::disableStop(uint32_t code) {
+  if (isEnabledStop(code)) {
+    watchedStops_[code].count_ |= kStopDisabledBit;
+  }
+}
+
+void Simulator::increaseStopCounter(uint32_t code) {
+  MOZ_ASSERT(code <= kMaxStopCode);
+  if ((watchedStops_[code].count_ & ~(1 << 31)) == 0x7fffffff) {
+    printf(
+        "Stop counter for code %i has overflowed.\n"
+        "Enabling this code and reseting the counter to 0.\n",
+        code);
+    watchedStops_[code].count_ = 0;
+    enableStop(code);
+  } else {
+    watchedStops_[code].count_++;
+  }
+}
+
+// Print a stop status.
+void Simulator::printStopInfo(uint32_t code) {
+  if (code <= kMaxWatchpointCode) {
+    printf("That is a watchpoint, not a stop.\n");
+    return;
+  } else if (code > kMaxStopCode) {
+    printf("Code too large, only %u stops can be used\n", kMaxStopCode + 1);
+    return;
+  }
+  const char* state = isEnabledStop(code) ? "Enabled" : "Disabled";
+  int32_t count = watchedStops_[code].count_ & ~kStopDisabledBit;
+  // Don't print the state of unused breakpoints.
+  if (count != 0) {
+    if (watchedStops_[code].desc_) {
+      printf("stop %i - 0x%x: \t%s, \tcounter = %i, \t%s\n", code, code, state,
+             count, watchedStops_[code].desc_);
+    } else {
+      printf("stop %i - 0x%x: \t%s, \tcounter = %i\n", code, code, state,
+             count);
+    }
+  }
+}
+
+void Simulator::SignalException(Exception e) {
+  printf("Error: Exception %i raised.", static_cast<int>(e));
+  MOZ_CRASH();
+}
+
+// TODO(plind): refactor this messy debug code when we do unaligned access.
+void Simulator::DieOrDebug() {
+  if (FLAG_riscv_trap_to_simulator_debugger) {
+    RiscvDebugger dbg(this);
+    dbg.Debug();
+  } else {
+    MOZ_CRASH("Die");
+  }
+}
+
+// Executes the current instruction.
+void Simulator::InstructionDecode(Instruction* instr) {
+  // if (FLAG_check_icache) {
+  //   CheckICache(SimulatorProcess::icache(), instr);
+  // }
+  pc_modified_ = false;
+
+  EmbeddedVector<char, 256> buffer;
+
+  if (FLAG_trace_sim || FLAG_debug_sim) {
+    SNPrintF(trace_buf_, " ");
+    disasm::NameConverter converter;
+    disasm::Disassembler dasm(converter);
+    // Use a reasonably large buffer.
+    dasm.InstructionDecode(buffer, reinterpret_cast<byte*>(instr));
+
+    // printf("EXECUTING  0x%08" PRIxPTR "   %-44s\n",
+    //        reinterpret_cast<intptr_t>(instr), buffer.begin());
+  }
+
+  instr_ = instr;
+  switch (instr_.InstructionType()) {
+    case Instruction::kRType:
+      DecodeRVRType();
+      break;
+    case Instruction::kR4Type:
+      DecodeRVR4Type();
+      break;
+    case Instruction::kIType:
+      DecodeRVIType();
+      break;
+    case Instruction::kSType:
+      DecodeRVSType();
+      break;
+    case Instruction::kBType:
+      DecodeRVBType();
+      break;
+    case Instruction::kUType:
+      DecodeRVUType();
+      break;
+    case Instruction::kJType:
+      DecodeRVJType();
+      break;
+    case Instruction::kCRType:
+      DecodeCRType();
+      break;
+    case Instruction::kCAType:
+      DecodeCAType();
+      break;
+    case Instruction::kCJType:
+      DecodeCJType();
+      break;
+    case Instruction::kCBType:
+      DecodeCBType();
+      break;
+    case Instruction::kCIType:
+      DecodeCIType();
+      break;
+    case Instruction::kCIWType:
+      DecodeCIWType();
+      break;
+    case Instruction::kCSSType:
+      DecodeCSSType();
+      break;
+    case Instruction::kCLType:
+      DecodeCLType();
+      break;
+    case Instruction::kCSType:
+      DecodeCSType();
+      break;
+#  ifdef CAN_USE_RVV_INSTRUCTIONS
+    case Instruction::kVType:
+      DecodeVType();
+      break;
+#  endif
+    default:
+      UNSUPPORTED();
+  }
+
+  if (FLAG_trace_sim) {
+    printf("  0x%012" PRIxPTR "      %-44s\t%s\n",
+           reinterpret_cast<intptr_t>(instr), buffer.start(),
+           trace_buf_.start());
+  }
+
+  if (!pc_modified_) {
+    setRegister(pc, reinterpret_cast<sreg_t>(instr) + instr->InstructionSize());
+  }
+
+  if (watch_address_ != nullptr) {
+    printf("  0x%012" PRIxPTR " :  0x%016" REGIx_FORMAT "  %14" REGId_FORMAT
+           " \n",
+           reinterpret_cast<intptr_t>(watch_address_), *watch_address_,
+           *watch_address_);
+    if (watch_value_ != *watch_address_) {
+      RiscvDebugger dbg(this);
+      dbg.Debug();
+      watch_value_ = *watch_address_;
+    }
+  }
+}
+
+void Simulator::enable_single_stepping(SingleStepCallback cb, void* arg) {
+  single_stepping_ = true;
+  single_step_callback_ = cb;
+  single_step_callback_arg_ = arg;
+  single_step_callback_(single_step_callback_arg_, this, (void*)get_pc());
+}
+
+void Simulator::disable_single_stepping() {
+  if (!single_stepping_) {
+    return;
+  }
+  single_step_callback_(single_step_callback_arg_, this, (void*)get_pc());
+  single_stepping_ = false;
+  single_step_callback_ = nullptr;
+  single_step_callback_arg_ = nullptr;
+}
+
+template <bool enableStopSimAt>
+void Simulator::execute() {
+  if (single_stepping_) {
+    single_step_callback_(single_step_callback_arg_, this, nullptr);
+  }
+
+  // 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.
+  int64_t program_counter = get_pc();
+
+  while (program_counter != end_sim_pc) {
+    if (enableStopSimAt && (icount_ == Simulator::StopSimAt)) {
+      RiscvDebugger dbg(this);
+      dbg.Debug();
+    }
+    if (single_stepping_) {
+      single_step_callback_(single_step_callback_arg_, this,
+                            (void*)program_counter);
+    }
+    Instruction* instr = reinterpret_cast<Instruction*>(program_counter);
+    InstructionDecode(instr);
+    icount_++;
+    program_counter = get_pc();
+  }
+
+  if (single_stepping_) {
+    single_step_callback_(single_step_callback_arg_, this, nullptr);
+  }
+}
+
+// RISCV Instruction Decode Routine
+void Simulator::DecodeRVRType() {
+  switch (instr_.InstructionBits() & kRTypeMask) {
+    case RO_ADD: {
+      set_rd(sext_xlen(rs1() + rs2()));
+      break;
+    }
+    case RO_SUB: {
+      set_rd(sext_xlen(rs1() - rs2()));
+      break;
+    }
+    case RO_SLL: {
+      set_rd(sext_xlen(rs1() << (rs2() & (xlen - 1))));
+      break;
+    }
+    case RO_SLT: {
+      set_rd(sreg_t(rs1()) < sreg_t(rs2()));
+      break;
+    }
+    case RO_SLTU: {
+      set_rd(reg_t(rs1()) < reg_t(rs2()));
+      break;
+    }
+    case RO_XOR: {
+      set_rd(rs1() ^ rs2());
+      break;
+    }
+    case RO_SRL: {
+      set_rd(sext_xlen(zext_xlen(rs1()) >> (rs2() & (xlen - 1))));
+      break;
+    }
+    case RO_SRA: {
+      set_rd(sext_xlen(sext_xlen(rs1()) >> (rs2() & (xlen - 1))));
+      break;
+    }
+    case RO_OR: {
+      set_rd(rs1() | rs2());
+      break;
+    }
+    case RO_AND: {
+      set_rd(rs1() & rs2());
+      break;
+    }
+#  ifdef JS_CODEGEN_RISCV64
+    case RO_ADDW: {
+      set_rd(sext32(rs1() + rs2()));
+      break;
+    }
+    case RO_SUBW: {
+      set_rd(sext32(rs1() - rs2()));
+      break;
+    }
+    case RO_SLLW: {
+      set_rd(sext32(rs1() << (rs2() & 0x1F)));
+      break;
+    }
+    case RO_SRLW: {
+      set_rd(sext32(uint32_t(rs1()) >> (rs2() & 0x1F)));
+      break;
+    }
+    case RO_SRAW: {
+      set_rd(sext32(int32_t(rs1()) >> (rs2() & 0x1F)));
+      break;
+    }
+#  endif /* JS_CODEGEN_RISCV64 */
+      // TODO(riscv): Add RISCV M extension macro
+    case RO_MUL: {
+      set_rd(rs1() * rs2());
+      break;
+    }
+    case RO_MULH: {
+      set_rd(mulh(rs1(), rs2()));
+      break;
+    }
+    case RO_MULHSU: {
+      set_rd(mulhsu(rs1(), rs2()));
+      break;
+    }
+    case RO_MULHU: {
+      set_rd(mulhu(rs1(), rs2()));
+      break;
+    }
+    case RO_DIV: {
+      sreg_t lhs = sext_xlen(rs1());
+      sreg_t rhs = sext_xlen(rs2());
+      if (rhs == 0) {
+        set_rd(-1);
+      } else if (lhs == INTPTR_MIN && rhs == -1) {
+        set_rd(lhs);
+      } else {
+        set_rd(sext_xlen(lhs / rhs));
+      }
+      break;
+    }
+    case RO_DIVU: {
+      reg_t lhs = zext_xlen(rs1());
+      reg_t rhs = zext_xlen(rs2());
+      if (rhs == 0) {
+        set_rd(UINTPTR_MAX);
+      } else {
+        set_rd(zext_xlen(lhs / rhs));
+      }
+      break;
+    }
+    case RO_REM: {
+      sreg_t lhs = sext_xlen(rs1());
+      sreg_t rhs = sext_xlen(rs2());
+      if (rhs == 0) {
+        set_rd(lhs);
+      } else if (lhs == INTPTR_MIN && rhs == -1) {
+        set_rd(0);
+      } else {
+        set_rd(sext_xlen(lhs % rhs));
+      }
+      break;
+    }
+    case RO_REMU: {
+      reg_t lhs = zext_xlen(rs1());
+      reg_t rhs = zext_xlen(rs2());
+      if (rhs == 0) {
+        set_rd(lhs);
+      } else {
+        set_rd(zext_xlen(lhs % rhs));
+      }
+      break;
+    }
+#  ifdef JS_CODEGEN_RISCV64
+    case RO_MULW: {
+      set_rd(sext32(sext32(rs1()) * sext32(rs2())));
+      break;
+    }
+    case RO_DIVW: {
+      sreg_t lhs = sext32(rs1());
+      sreg_t rhs = sext32(rs2());
+      if (rhs == 0) {
+        set_rd(-1);
+      } else if (lhs == INT32_MIN && rhs == -1) {
+        set_rd(lhs);
+      } else {
+        set_rd(sext32(lhs / rhs));
+      }
+      break;
+    }
+    case RO_DIVUW: {
+      reg_t lhs = zext32(rs1());
+      reg_t rhs = zext32(rs2());
+      if (rhs == 0) {
+        set_rd(UINT32_MAX);
+      } else {
+        set_rd(zext32(lhs / rhs));
+      }
+      break;
+    }
+    case RO_REMW: {
+      sreg_t lhs = sext32(rs1());
+      sreg_t rhs = sext32(rs2());
+      if (rhs == 0) {
+        set_rd(lhs);
+      } else if (lhs == INT32_MIN && rhs == -1) {
+        set_rd(0);
+      } else {
+        set_rd(sext32(lhs % rhs));
+      }
+      break;
+    }
+    case RO_REMUW: {
+      reg_t lhs = zext32(rs1());
+      reg_t rhs = zext32(rs2());
+      if (rhs == 0) {
+        set_rd(zext32(lhs));
+      } else {
+        set_rd(zext32(lhs % rhs));
+      }
+      break;
+    }
+#  endif /*JS_CODEGEN_RISCV64*/
+      // TODO(riscv): End Add RISCV M extension macro
+    default: {
+      switch (instr_.BaseOpcode()) {
+        case AMO:
+          DecodeRVRAType();
+          break;
+        case OP_FP:
+          DecodeRVRFPType();
+          break;
+        default:
+          UNSUPPORTED();
+      }
+    }
+  }
+}
+
+template <typename T>
+T Simulator::FMaxMinHelper(T a, T b, MaxMinKind kind) {
+  // set invalid bit for signaling nan
+  if ((a == std::numeric_limits<T>::signaling_NaN()) ||
+      (b == std::numeric_limits<T>::signaling_NaN())) {
+    set_csr_bits(csr_fflags, kInvalidOperation);
+  }
+
+  T result = 0;
+  if (std::isnan(a) && std::isnan(b)) {
+    result = std::numeric_limits<float>::quiet_NaN();
+  } else if (std::isnan(a)) {
+    result = b;
+  } else if (std::isnan(b)) {
+    result = a;
+  } else if (b == a) {  // Handle -0.0 == 0.0 case.
+    if (kind == MaxMinKind::kMax) {
+      result = std::signbit(b) ? a : b;
+    } else {
+      result = std::signbit(b) ? b : a;
+    }
+  } else {
+    result = (kind == MaxMinKind::kMax) ? fmax(a, b) : fmin(a, b);
+  }
+
+  return result;
+}
+
+float Simulator::RoundF2FHelper(float input_val, int rmode) {
+  if (rmode == DYN) rmode = get_dynamic_rounding_mode();
+
+  float rounded = 0;
+  switch (rmode) {
+    case RNE: {  // Round to Nearest, tiest to Even
+      rounded = floorf(input_val);
+      float error = input_val - rounded;
+
+      // Take care of correctly handling the range [-0.5, -0.0], which must
+      // yield -0.0.
+      if ((-0.5 <= input_val) && (input_val < 0.0)) {
+        rounded = -0.0;
+
+        // If the error is greater than 0.5, or is equal to 0.5 and the integer
+        // result is odd, round up.
+      } else if ((error > 0.5) ||
+                 ((error == 0.5) && (std::fmod(rounded, 2) != 0))) {
+        rounded++;
+      }
+      break;
+    }
+    case RTZ:  // Round towards Zero
+      rounded = std::truncf(input_val);
+      break;
+    case RDN:  // Round Down (towards -infinity)
+      rounded = floorf(input_val);
+      break;
+    case RUP:  // Round Up (towards +infinity)
+      rounded = ceilf(input_val);
+      break;
+    case RMM:  // Round to Nearest, tiest to Max Magnitude
+      rounded = std::roundf(input_val);
+      break;
+    default:
+      UNREACHABLE();
+  }
+
+  return rounded;
+}
+
+double Simulator::RoundF2FHelper(double input_val, int rmode) {
+  if (rmode == DYN) rmode = get_dynamic_rounding_mode();
+
+  double rounded = 0;
+  switch (rmode) {
+    case RNE: {  // Round to Nearest, tiest to Even
+      rounded = std::floor(input_val);
+      double error = input_val - rounded;
+
+      // Take care of correctly handling the range [-0.5, -0.0], which must
+      // yield -0.0.
+      if ((-0.5 <= input_val) && (input_val < 0.0)) {
+        rounded = -0.0;
+
+        // If the error is greater than 0.5, or is equal to 0.5 and the integer
+        // result is odd, round up.
+      } else if ((error > 0.5) ||
+                 ((error == 0.5) && (std::fmod(rounded, 2) != 0))) {
+        rounded++;
+      }
+      break;
+    }
+    case RTZ:  // Round towards Zero
+      rounded = std::trunc(input_val);
+      break;
+    case RDN:  // Round Down (towards -infinity)
+      rounded = std::floor(input_val);
+      break;
+    case RUP:  // Round Up (towards +infinity)
+      rounded = std::ceil(input_val);
+      break;
+    case RMM:  // Round to Nearest, tiest to Max Magnitude
+      rounded = std::round(input_val);
+      break;
+    default:
+      UNREACHABLE();
+  }
+  return rounded;
+}
+
+// convert rounded floating-point to integer types, handle input values that
+// are out-of-range, underflow, or NaN, and set appropriate fflags
+template <typename I_TYPE, typename F_TYPE>
+I_TYPE Simulator::RoundF2IHelper(F_TYPE original, int rmode) {
+  MOZ_ASSERT(std::is_integral<I_TYPE>::value);
+
+  MOZ_ASSERT((std::is_same<F_TYPE, float>::value ||
+              std::is_same<F_TYPE, double>::value));
+
+  I_TYPE max_i = std::numeric_limits<I_TYPE>::max();
+  I_TYPE min_i = std::numeric_limits<I_TYPE>::min();
+
+  if (!std::isfinite(original)) {
+    set_fflags(kInvalidOperation);
+    if (std::isnan(original) ||
+        original == std::numeric_limits<F_TYPE>::infinity()) {
+      return max_i;
+    } else {
+      MOZ_ASSERT(original == -std::numeric_limits<F_TYPE>::infinity());
+      return min_i;
+    }
+  }
+
+  F_TYPE rounded = RoundF2FHelper(original, rmode);
+  if (original != rounded) set_fflags(kInexact);
+
+  if (!std::isfinite(rounded)) {
+    set_fflags(kInvalidOperation);
+    if (std::isnan(rounded) ||
+        rounded == std::numeric_limits<F_TYPE>::infinity()) {
+      return max_i;
+    } else {
+      MOZ_ASSERT(rounded == -std::numeric_limits<F_TYPE>::infinity());
+      return min_i;
+    }
+  }
+
+  // Since integer max values are either all 1s (for unsigned) or all 1s
+  // except for sign-bit (for signed), they cannot be represented precisely in
+  // floating point, in order to precisely tell whether the rounded floating
+  // point is within the max range, we compare against (max_i+1) which would
+  // have a single 1 w/ many trailing zeros
+  float max_i_plus_1 =
+      std::is_same<uint64_t, I_TYPE>::value
+          ? 0x1p64f  // uint64_t::max + 1 cannot be represented in integers,
+                     // so use its float representation directly
+          : static_cast<float>(static_cast<uint64_t>(max_i) + 1);
+  if (rounded >= max_i_plus_1) {
+    set_fflags(kOverflow | kInvalidOperation);
+    return max_i;
+  }
+
+  // Since min_i (either 0 for unsigned, or for signed) is represented
+  // precisely in floating-point,  comparing rounded directly against min_i
+  if (rounded <= min_i) {
+    if (rounded < min_i) set_fflags(kOverflow | kInvalidOperation);
+    return min_i;
+  }
+
+  F_TYPE underflow_fval =
+      std::is_same<F_TYPE, float>::value ? FLT_MIN : DBL_MIN;
+  if (rounded < underflow_fval && rounded > -underflow_fval && rounded != 0) {
+    set_fflags(kUnderflow);
+  }
+
+  return static_cast<I_TYPE>(rounded);
+}
+
+template <typename T>
+static int64_t FclassHelper(T value) {
+  switch (std::fpclassify(value)) {
+    case FP_INFINITE:
+      return (std::signbit(value) ? kNegativeInfinity : kPositiveInfinity);
+    case FP_NAN:
+      return (isSnan(value) ? kSignalingNaN : kQuietNaN);
+    case FP_NORMAL:
+      return (std::signbit(value) ? kNegativeNormalNumber
+                                  : kPositiveNormalNumber);
+    case FP_SUBNORMAL:
+      return (std::signbit(value) ? kNegativeSubnormalNumber
+                                  : kPositiveSubnormalNumber);
+    case FP_ZERO:
+      return (std::signbit(value) ? kNegativeZero : kPositiveZero);
+    default:
+      UNREACHABLE();
+  }
+  UNREACHABLE();
+  return FP_ZERO;
+}
+
+template <typename T>
+bool Simulator::CompareFHelper(T input1, T input2, FPUCondition cc) {
+  MOZ_ASSERT(std::is_floating_point<T>::value);
+  bool result = false;
+  switch (cc) {
+    case LT:
+    case LE:
+      // FLT, FLE are signaling compares
+      if (std::isnan(input1) || std::isnan(input2)) {
+        set_fflags(kInvalidOperation);
+        result = false;
+      } else {
+        result = (cc == LT) ? (input1 < input2) : (input1 <= input2);
+      }
+      break;
+    case EQ:
+      if (std::numeric_limits<T>::signaling_NaN() == input1 ||
+          std::numeric_limits<T>::signaling_NaN() == input2) {
+        set_fflags(kInvalidOperation);
+      }
+      if (std::isnan(input1) || std::isnan(input2)) {
+        result = false;
+      } else {
+        result = (input1 == input2);
+      }
+      break;
+    case NE:
+      if (std::numeric_limits<T>::signaling_NaN() == input1 ||
+          std::numeric_limits<T>::signaling_NaN() == input2) {
+        set_fflags(kInvalidOperation);
+      }
+      if (std::isnan(input1) || std::isnan(input2)) {
+        result = true;
+      } else {
+        result = (input1 != input2);
+      }
+      break;
+    default:
+      UNREACHABLE();
+  }
+  return result;
+}
+
+template <typename T>
+static inline bool is_invalid_fmul(T src1, T src2) {
+  return (isinf(src1) && src2 == static_cast<T>(0.0)) ||
+         (src1 == static_cast<T>(0.0) && isinf(src2));
+}
+
+template <typename T>
+static inline bool is_invalid_fadd(T src1, T src2) {
+  return (isinf(src1) && isinf(src2) &&
+          std::signbit(src1) != std::signbit(src2));
+}
+
+template <typename T>
+static inline bool is_invalid_fsub(T src1, T src2) {
+  return (isinf(src1) && isinf(src2) &&
+          std::signbit(src1) == std::signbit(src2));
+}
+
+template <typename T>
+static inline bool is_invalid_fdiv(T src1, T src2) {
+  return ((src1 == 0 && src2 == 0) || (isinf(src1) && isinf(src2)));
+}
+
+template <typename T>
+static inline bool is_invalid_fsqrt(T src1) {
+  return (src1 < 0);
+}
+
+int Simulator::loadLinkedW(uint64_t addr, SimInstruction* instr) {
+  if ((addr & 3) == 0) {
+    if (handleWasmSegFault(addr, 4)) {
+      return -1;
+    }
+
+    volatile int32_t* ptr = reinterpret_cast<volatile int32_t*>(addr);
+    int32_t value = *ptr;
+    lastLLValue_ = value;
+    LLAddr_ = addr;
+    // Note that any memory write or "external" interrupt should reset this
+    // value to false.
+    LLBit_ = true;
+    return value;
+  }
+  printf("Unaligned write at 0x%016" PRIx64 ", pc=0x%016" PRIxPTR "\n", addr,
+         reinterpret_cast<intptr_t>(instr));
+  MOZ_CRASH();
+  return 0;
+}
+
+int Simulator::storeConditionalW(uint64_t addr, int value,
+                                 SimInstruction* instr) {
+  // Correct behavior in this case, as defined by architecture, is to just
+  // return 0, but there is no point at allowing that. It is certainly an
+  // indicator of a bug.
+  if (addr != LLAddr_) {
+    printf("SC to bad address: 0x%016" PRIx64 ", pc=0x%016" PRIx64
+           ", expected: 0x%016" PRIx64 "\n",
+           addr, reinterpret_cast<intptr_t>(instr), LLAddr_);
+    MOZ_CRASH();
+  }
+
+  if ((addr & 3) == 0) {
+    SharedMem<int32_t*> ptr =
+        SharedMem<int32_t*>::shared(reinterpret_cast<int32_t*>(addr));
+
+    if (!LLBit_) {
+      return 1;
+    }
+
+    LLBit_ = false;
+    LLAddr_ = 0;
+    int32_t expected = int32_t(lastLLValue_);
+    int32_t old =
+        AtomicOperations::compareExchangeSeqCst(ptr, expected, int32_t(value));
+    return (old == expected) ? 0 : 1;
+  }
+  printf("Unaligned SC at 0x%016" PRIx64 ", pc=0x%016" PRIxPTR "\n", addr,
+         reinterpret_cast<intptr_t>(instr));
+  MOZ_CRASH();
+  return 0;
+}
+
+int64_t Simulator::loadLinkedD(uint64_t addr, SimInstruction* instr) {
+  if ((addr & kPointerAlignmentMask) == 0) {
+    if (handleWasmSegFault(addr, 8)) {
+      return -1;
+    }
+
+    volatile int64_t* ptr = reinterpret_cast<volatile int64_t*>(addr);
+    int64_t value = *ptr;
+    lastLLValue_ = value;
+    LLAddr_ = addr;
+    // Note that any memory write or "external" interrupt should reset this
+    // value to false.
+    LLBit_ = true;
+    return value;
+  }
+  printf("Unaligned write at 0x%016" PRIx64 ", pc=0x%016" PRIxPTR "\n", addr,
+         reinterpret_cast<intptr_t>(instr));
+  MOZ_CRASH();
+  return 0;
+}
+
+int Simulator::storeConditionalD(uint64_t addr, int64_t value,
+                                 SimInstruction* instr) {
+  // Correct behavior in this case, as defined by architecture, is to just
+  // return 0, but there is no point at allowing that. It is certainly an
+  // indicator of a bug.
+  if (addr != LLAddr_) {
+    printf("SC to bad address: 0x%016" PRIx64 ", pc=0x%016" PRIx64
+           ", expected: 0x%016" PRIx64 "\n",
+           addr, reinterpret_cast<intptr_t>(instr), LLAddr_);
+    MOZ_CRASH();
+  }
+
+  if ((addr & kPointerAlignmentMask) == 0) {
+    SharedMem<int64_t*> ptr =
+        SharedMem<int64_t*>::shared(reinterpret_cast<int64_t*>(addr));
+
+    if (!LLBit_) {
+      return 1;
+    }
+
+    LLBit_ = false;
+    LLAddr_ = 0;
+    int64_t expected = lastLLValue_;
+    int64_t old =
+        AtomicOperations::compareExchangeSeqCst(ptr, expected, int64_t(value));
+    return (old == expected) ? 0 : 1;
+  }
+  printf("Unaligned SC at 0x%016" PRIx64 ", pc=0x%016" PRIxPTR "\n", addr,
+         reinterpret_cast<intptr_t>(instr));
+  MOZ_CRASH();
+  return 0;
+}
+
+void Simulator::DecodeRVRAType() {
+  // TODO(riscv): Add macro for RISCV A extension
+  // Special handling for A extension instructions because it uses func5
+  // For all A extension instruction, V8 simulator is pure sequential. No
+  // Memory address lock or other synchronizaiton behaviors.
+  switch (instr_.InstructionBits() & kRATypeMask) {
+    case RO_LR_W: {
+      sreg_t addr = rs1();
+      set_rd(loadLinkedW(addr, &instr_));
+      TraceLr(addr, getRegister(rd_reg()), getRegister(rd_reg()));
+      break;
+    }
+    case RO_SC_W: {
+      sreg_t addr = rs1();
+      auto value = static_cast<int32_t>(rs2());
+      auto result =
+          storeConditionalW(addr, static_cast<int32_t>(rs2()), &instr_);
+      set_rd(result);
+      if (!result) {
+        TraceSc(addr, value);
+      }
+      break;
+    }
+    case RO_AMOSWAP_W: {
+      if ((rs1() & 0x3) != 0) {
+        DieOrDebug();
+      }
+      set_rd(sext32(amo<uint32_t>(
+          rs1(), [&](uint32_t lhs) { return (uint32_t)rs2(); }, instr_.instr(),
+          WORD)));
+      break;
+    }
+    case RO_AMOADD_W: {
+      if ((rs1() & 0x3) != 0) {
+        DieOrDebug();
+      }
+      set_rd(sext32(amo<uint32_t>(
+          rs1(), [&](uint32_t lhs) { return lhs + (uint32_t)rs2(); },
+          instr_.instr(), WORD)));
+      break;
+    }
+    case RO_AMOXOR_W: {
+      if ((rs1() & 0x3) != 0) {
+        DieOrDebug();
+      }
+      set_rd(sext32(amo<uint32_t>(
+          rs1(), [&](uint32_t lhs) { return lhs ^ (uint32_t)rs2(); },
+          instr_.instr(), WORD)));
+      break;
+    }
+    case RO_AMOAND_W: {
+      if ((rs1() & 0x3) != 0) {
+        DieOrDebug();
+      }
+      set_rd(sext32(amo<uint32_t>(
+          rs1(), [&](uint32_t lhs) { return lhs & (uint32_t)rs2(); },
+          instr_.instr(), WORD)));
+      break;
+    }
+    case RO_AMOOR_W: {
+      if ((rs1() & 0x3) != 0) {
+        DieOrDebug();
+      }
+      set_rd(sext32(amo<uint32_t>(
+          rs1(), [&](uint32_t lhs) { return lhs | (uint32_t)rs2(); },
+          instr_.instr(), WORD)));
+      break;
+    }
+    case RO_AMOMIN_W: {
+      if ((rs1() & 0x3) != 0) {
+        DieOrDebug();
+      }
+      set_rd(sext32(amo<int32_t>(
+          rs1(), [&](int32_t lhs) { return std::min(lhs, (int32_t)rs2()); },
+          instr_.instr(), WORD)));
+      break;
+    }
+    case RO_AMOMAX_W: {
+      if ((rs1() & 0x3) != 0) {
+        DieOrDebug();
+      }
+      set_rd(sext32(amo<int32_t>(
+          rs1(), [&](int32_t lhs) { return std::max(lhs, (int32_t)rs2()); },
+          instr_.instr(), WORD)));
+      break;
+    }
+    case RO_AMOMINU_W: {
+      if ((rs1() & 0x3) != 0) {
+        DieOrDebug();
+      }
+      set_rd(sext32(amo<uint32_t>(
+          rs1(), [&](uint32_t lhs) { return std::min(lhs, (uint32_t)rs2()); },
+          instr_.instr(), WORD)));
+      break;
+    }
+    case RO_AMOMAXU_W: {
+      if ((rs1() & 0x3) != 0) {
+        DieOrDebug();
+      }
+      set_rd(sext32(amo<uint32_t>(
+          rs1(), [&](uint32_t lhs) { return std::max(lhs, (uint32_t)rs2()); },
+          instr_.instr(), WORD)));
+      break;
+    }
+#  ifdef JS_CODEGEN_RISCV64
+    case RO_LR_D: {
+      sreg_t addr = rs1();
+      set_rd(loadLinkedD(addr, &instr_));
+      TraceLr(addr, getRegister(rd_reg()), getRegister(rd_reg()));
+      break;
+    }
+    case RO_SC_D: {
+      sreg_t addr = rs1();
+      auto value = static_cast<int64_t>(rs2());
+      auto result =
+          storeConditionalD(addr, static_cast<int64_t>(rs2()), &instr_);
+      set_rd(result);
+      if (!result) {
+        TraceSc(addr, value);
+      }
+      break;
+    }
+    case RO_AMOSWAP_D: {
+      set_rd(amo<int64_t>(
+          rs1(), [&](int64_t lhs) { return rs2(); }, instr_.instr(), DWORD));
+      break;
+    }
+    case RO_AMOADD_D: {
+      set_rd(amo<int64_t>(
+          rs1(), [&](int64_t lhs) { return lhs + rs2(); }, instr_.instr(),
+          DWORD));
+      break;
+    }
+    case RO_AMOXOR_D: {
+      set_rd(amo<int64_t>(
+          rs1(), [&](int64_t lhs) { return lhs ^ rs2(); }, instr_.instr(),
+          DWORD));
+      break;
+    }
+    case RO_AMOAND_D: {
+      set_rd(amo<int64_t>(
+          rs1(), [&](int64_t lhs) { return lhs & rs2(); }, instr_.instr(),
+          DWORD));
+      break;
+    }
+    case RO_AMOOR_D: {
+      set_rd(amo<int64_t>(
+          rs1(), [&](int64_t lhs) { return lhs | rs2(); }, instr_.instr(),
+          DWORD));
+      break;
+    }
+    case RO_AMOMIN_D: {
+      set_rd(amo<int64_t>(
+          rs1(), [&](int64_t lhs) { return std::min(lhs, rs2()); },
+          instr_.instr(), DWORD));
+      break;
+    }
+    case RO_AMOMAX_D: {
+      set_rd(amo<int64_t>(
+          rs1(), [&](int64_t lhs) { return std::max(lhs, rs2()); },
+          instr_.instr(), DWORD));
+      break;
+    }
+    case RO_AMOMINU_D: {
+      set_rd(amo<uint64_t>(
+          rs1(), [&](uint64_t lhs) { return std::min(lhs, (uint64_t)rs2()); },
+          instr_.instr(), DWORD));
+      break;
+    }
+    case RO_AMOMAXU_D: {
+      set_rd(amo<uint64_t>(
+          rs1(), [&](uint64_t lhs) { return std::max(lhs, (uint64_t)rs2()); },
+          instr_.instr(), DWORD));
+      break;
+    }
+#  endif /*JS_CODEGEN_RISCV64*/
+    // TODO(riscv): End Add macro for RISCV A extension
+    default: {
+      UNSUPPORTED();
+    }
+  }
+}
+
+void Simulator::DecodeRVRFPType() {
+  // OP_FP instructions (F/D) uses func7 first. Some further uses func3 and
+  // rs2()
+
+  // kRATypeMask is only for func7
+  switch (instr_.InstructionBits() & kRFPTypeMask) {
+    // TODO(riscv): Add macro for RISCV F extension
+    case RO_FADD_S: {
+      // TODO(riscv): use rm value (round mode)
+      auto fn = [this](float frs1, float frs2) {
+        if (is_invalid_fadd(frs1, frs2)) {
+          this->set_fflags(kInvalidOperation);
+          return std::numeric_limits<float>::quiet_NaN();
+        } else {
+          return frs1 + frs2;
+        }
+      };
+      set_frd(CanonicalizeFPUOp2<float>(fn));
+      break;
+    }
+    case RO_FSUB_S: {
+      // TODO(riscv): use rm value (round mode)
+      auto fn = [this](float frs1, float frs2) {
+        if (is_invalid_fsub(frs1, frs2)) {
+          this->set_fflags(kInvalidOperation);
+          return std::numeric_limits<float>::quiet_NaN();
+        } else {
+          return frs1 - frs2;
+        }
+      };
+      set_frd(CanonicalizeFPUOp2<float>(fn));
+      break;
+    }
+    case RO_FMUL_S: {
+      // TODO(riscv): use rm value (round mode)
+      auto fn = [this](float frs1, float frs2) {
+        if (is_invalid_fmul(frs1, frs2)) {
+          this->set_fflags(kInvalidOperation);
+          return std::numeric_limits<float>::quiet_NaN();
+        } else {
+          return frs1 * frs2;
+        }
+      };
+      set_frd(CanonicalizeFPUOp2<float>(fn));
+      break;
+    }
+    case RO_FDIV_S: {
+      // TODO(riscv): use rm value (round mode)
+      auto fn = [this](float frs1, float frs2) {
+        if (is_invalid_fdiv(frs1, frs2)) {
+          this->set_fflags(kInvalidOperation);
+          return std::numeric_limits<float>::quiet_NaN();
+        } else if (frs2 == 0.0f) {
+          this->set_fflags(kDivideByZero);
+          return (std::signbit(frs1) == std::signbit(frs2)
+                      ? std::numeric_limits<float>::infinity()
+                      : -std::numeric_limits<float>::infinity());
+        } else {
+          return frs1 / frs2;
+        }
+      };
+      set_frd(CanonicalizeFPUOp2<float>(fn));
+      break;
+    }
+    case RO_FSQRT_S: {
+      if (instr_.Rs2Value() == 0b00000) {
+        // TODO(riscv): use rm value (round mode)
+        auto fn = [this](float frs) {
+          if (is_invalid_fsqrt(frs)) {
+            this->set_fflags(kInvalidOperation);
+            return std::numeric_limits<float>::quiet_NaN();
+          } else {
+            return std::sqrt(frs);
+          }
+        };
+        set_frd(CanonicalizeFPUOp1<float>(fn));
+      } else {
+        UNSUPPORTED();
+      }
+      break;
+    }
+    case RO_FSGNJ_S: {  // RO_FSGNJN_S  RO_FSQNJX_S
+      switch (instr_.Funct3Value()) {
+        case 0b000: {  // RO_FSGNJ_S
+          set_frd(fsgnj32(frs1_boxed(), frs2_boxed(), false, false));
+          break;
+        }
+        case 0b001: {  // RO_FSGNJN_S
+          set_frd(fsgnj32(frs1_boxed(), frs2_boxed(), true, false));
+          break;
+        }
+        case 0b010: {  // RO_FSQNJX_S
+          set_frd(fsgnj32(frs1_boxed(), frs2_boxed(), false, true));
+          break;
+        }
+        default: {
+          UNSUPPORTED();
+        }
+      }
+      break;
+    }
+    case RO_FMIN_S: {  // RO_FMAX_S
+      switch (instr_.Funct3Value()) {
+        case 0b000: {  // RO_FMIN_S
+          set_frd(FMaxMinHelper(frs1(), frs2(), MaxMinKind::kMin));
+          break;
+        }
+        case 0b001: {  // RO_FMAX_S
+          set_frd(FMaxMinHelper(frs1(), frs2(), MaxMinKind::kMax));
+          break;
+        }
+        default: {
+          UNSUPPORTED();
+        }
+      }
+      break;
+    }
+    case RO_FCVT_W_S: {  // RO_FCVT_WU_S , 64F RO_FCVT_L_S RO_FCVT_LU_S
+      float original_val = frs1();
+      switch (instr_.Rs2Value()) {
+        case 0b00000: {  // RO_FCVT_W_S
+          set_rd(RoundF2IHelper<int32_t>(original_val, instr_.RoundMode()));
+          break;
+        }
+        case 0b00001: {  // RO_FCVT_WU_S
+          set_rd(sext32(
+              RoundF2IHelper<uint32_t>(original_val, instr_.RoundMode())));
+          break;
+        }
+#  ifdef JS_CODEGEN_RISCV64
+        case 0b00010: {  // RO_FCVT_L_S
+          set_rd(RoundF2IHelper<int64_t>(original_val, instr_.RoundMode()));
+          break;
+        }
+        case 0b00011: {  // RO_FCVT_LU_S
+          set_rd(RoundF2IHelper<uint64_t>(original_val, instr_.RoundMode()));
+          break;
+        }
+#  endif /* JS_CODEGEN_RISCV64 */
+        default: {
+          UNSUPPORTED();
+        }
+      }
+      break;
+    }
+    case RO_FMV: {  // RO_FCLASS_S
+      switch (instr_.Funct3Value()) {
+        case 0b000: {
+          if (instr_.Rs2Value() == 0b00000) {
+            // RO_FMV_X_W
+            set_rd(sext32(getFpuRegister(rs1_reg())));
+          } else {
+            UNSUPPORTED();
+          }
+          break;
+        }
+        case 0b001: {  // RO_FCLASS_S
+          set_rd(FclassHelper(frs1()));
+          break;
+        }
+        default: {
+          UNSUPPORTED();
+        }
+      }
+      break;
+    }
+    case RO_FLE_S: {  // RO_FEQ_S RO_FLT_S RO_FLE_S
+      switch (instr_.Funct3Value()) {
+        case 0b010: {  // RO_FEQ_S
+          set_rd(CompareFHelper(frs1(), frs2(), EQ));
+          break;
+        }
+        case 0b001: {  // RO_FLT_S
+          set_rd(CompareFHelper(frs1(), frs2(), LT));
+          break;
+        }
+        case 0b000: {  // RO_FLE_S
+          set_rd(CompareFHelper(frs1(), frs2(), LE));
+          break;
+        }
+        default: {
+          UNSUPPORTED();
+        }
+      }
+      break;
+    }
+    case RO_FCVT_S_W: {  // RO_FCVT_S_WU , 64F RO_FCVT_S_L RO_FCVT_S_LU
+      switch (instr_.Rs2Value()) {
+        case 0b00000: {  // RO_FCVT_S_W
+          set_frd(static_cast<float>((int32_t)rs1()));
+          break;
+        }
+        case 0b00001: {  // RO_FCVT_S_WU
+          set_frd(static_cast<float>((uint32_t)rs1()));
+          break;
+        }
+#  ifdef JS_CODEGEN_RISCV64
+        case 0b00010: {  // RO_FCVT_S_L
+          set_frd(static_cast<float>((int64_t)rs1()));
+          break;
+        }
+        case 0b00011: {  // RO_FCVT_S_LU
+          set_frd(static_cast<float>((uint64_t)rs1()));
+          break;
+        }
+#  endif /* JS_CODEGEN_RISCV64 */
+        default: {
+          UNSUPPORTED();
+        }
+      }
+      break;
+    }
+    case RO_FMV_W_X: {
+      if (instr_.Funct3Value() == 0b000) {
+        // since FMV preserves source bit-pattern, no need to canonize
+        Float32 result = Float32::FromBits((uint32_t)rs1());
+        set_frd(result);
+      } else {
+        UNSUPPORTED();
+      }
+      break;
+    }
+      // TODO(riscv): Add macro for RISCV D extension
+    case RO_FADD_D: {
+      // TODO(riscv): use rm value (round mode)
+      auto fn = [this](double drs1, double drs2) {
+        if (is_invalid_fadd(drs1, drs2)) {
+          this->set_fflags(kInvalidOperation);
+          return std::numeric_limits<double>::quiet_NaN();
+        } else {
+          return drs1 + drs2;
+        }
+      };
+      set_drd(CanonicalizeFPUOp2<double>(fn));
+      break;
+    }
+    case RO_FSUB_D: {
+      // TODO(riscv): use rm value (round mode)
+      auto fn = [this](double drs1, double drs2) {
+        if (is_invalid_fsub(drs1, drs2)) {
+          this->set_fflags(kInvalidOperation);
+          return std::numeric_limits<double>::quiet_NaN();
+        } else {
+          return drs1 - drs2;
+        }
+      };
+      set_drd(CanonicalizeFPUOp2<double>(fn));
+      break;
+    }
+    case RO_FMUL_D: {
+      // TODO(riscv): use rm value (round mode)
+      auto fn = [this](double drs1, double drs2) {
+        if (is_invalid_fmul(drs1, drs2)) {
+          this->set_fflags(kInvalidOperation);
+          return std::numeric_limits<double>::quiet_NaN();
+        } else {
+          return drs1 * drs2;
+        }
+      };
+      set_drd(CanonicalizeFPUOp2<double>(fn));
+      break;
+    }
+    case RO_FDIV_D: {
+      // TODO(riscv): use rm value (round mode)
+      auto fn = [this](double drs1, double drs2) {
+        if (is_invalid_fdiv(drs1, drs2)) {
+          this->set_fflags(kInvalidOperation);
+          return std::numeric_limits<double>::quiet_NaN();
+        } else if (drs2 == 0.0) {
+          this->set_fflags(kDivideByZero);
+          return (std::signbit(drs1) == std::signbit(drs2)
+                      ? std::numeric_limits<double>::infinity()
+                      : -std::numeric_limits<double>::infinity());
+        } else {
+          return drs1 / drs2;
+        }
+      };
+      set_drd(CanonicalizeFPUOp2<double>(fn));
+      break;
+    }
+    case RO_FSQRT_D: {
+      if (instr_.Rs2Value() == 0b00000) {
+        // TODO(riscv): use rm value (round mode)
+        auto fn = [this](double drs) {
+          if (is_invalid_fsqrt(drs)) {
+            this->set_fflags(kInvalidOperation);
+            return std::numeric_limits<double>::quiet_NaN();
+          } else {
+            return std::sqrt(drs);
+          }
+        };
+        set_drd(CanonicalizeFPUOp1<double>(fn));
+      } else {
+        UNSUPPORTED();
+      }
+      break;
+    }
+    case RO_FSGNJ_D: {  // RO_FSGNJN_D RO_FSQNJX_D
+      switch (instr_.Funct3Value()) {
+        case 0b000: {  // RO_FSGNJ_D
+          set_drd(fsgnj64(drs1_boxed(), drs2_boxed(), false, false));
+          break;
+        }
+        case 0b001: {  // RO_FSGNJN_D
+          set_drd(fsgnj64(drs1_boxed(), drs2_boxed(), true, false));
+          break;
+        }
+        case 0b010: {  // RO_FSQNJX_D
+          set_drd(fsgnj64(drs1_boxed(), drs2_boxed(), false, true));
+          break;
+        }
+        default: {
+          UNSUPPORTED();
+        }
+      }
+      break;
+    }
+    case RO_FMIN_D: {  // RO_FMAX_D
+      switch (instr_.Funct3Value()) {
+        case 0b000: {  // RO_FMIN_D
+          set_drd(FMaxMinHelper(drs1(), drs2(), MaxMinKind::kMin));
+          break;
+        }
+        case 0b001: {  // RO_FMAX_D
+          set_drd(FMaxMinHelper(drs1(), drs2(), MaxMinKind::kMax));
+          break;
+        }
+        default: {
+          UNSUPPORTED();
+        }
+      }
+      break;
+    }
+    case (RO_FCVT_S_D & kRFPTypeMask): {
+      if (instr_.Rs2Value() == 0b00001) {
+        auto fn = [](double drs) { return static_cast<float>(drs); };
+        set_frd(CanonicalizeDoubleToFloatOperation(fn));
+      } else {
+        UNSUPPORTED();
+      }
+      break;
+    }
+    case RO_FCVT_D_S: {
+      if (instr_.Rs2Value() == 0b00000) {
+        auto fn = [](float frs) { return static_cast<double>(frs); };
+        set_drd(CanonicalizeFloatToDoubleOperation(fn));
+      } else {
+        UNSUPPORTED();
+      }
+      break;
+    }
+    case RO_FLE_D: {  // RO_FEQ_D RO_FLT_D RO_FLE_D
+      switch (instr_.Funct3Value()) {
+        case 0b010: {  // RO_FEQ_S
+          set_rd(CompareFHelper(drs1(), drs2(), EQ));
+          break;
+        }
+        case 0b001: {  // RO_FLT_D
+          set_rd(CompareFHelper(drs1(), drs2(), LT));
+          break;
+        }
+        case 0b000: {  // RO_FLE_D
+          set_rd(CompareFHelper(drs1(), drs2(), LE));
+          break;
+        }
+        default: {
+          UNSUPPORTED();
+        }
+      }
+      break;
+    }
+    case (RO_FCLASS_D & kRFPTypeMask): {  // RO_FCLASS_D , 64D RO_FMV_X_D
+      if (instr_.Rs2Value() != 0b00000) {
+        UNSUPPORTED();
+      }
+      switch (instr_.Funct3Value()) {
+        case 0b001: {  // RO_FCLASS_D
+          set_rd(FclassHelper(drs1()));
+          break;
+        }
+#  ifdef JS_CODEGEN_RISCV64
+        case 0b000: {  // RO_FMV_X_D
+          set_rd(bit_cast<int64_t>(drs1()));
+          break;
+        }
+#  endif /* JS_CODEGEN_RISCV64 */
+        default: {
+          UNSUPPORTED();
+        }
+      }
+      break;
+    }
+    case RO_FCVT_W_D: {  // RO_FCVT_WU_D , 64F RO_FCVT_L_D RO_FCVT_LU_D
+      double original_val = drs1();
+      switch (instr_.Rs2Value()) {
+        case 0b00000: {  // RO_FCVT_W_D
+          set_rd(RoundF2IHelper<int32_t>(original_val, instr_.RoundMode()));
+          break;
+        }
+        case 0b00001: {  // RO_FCVT_WU_D
+          set_rd(sext32(
+              RoundF2IHelper<uint32_t>(original_val, instr_.RoundMode())));
+          break;
+        }
+#  ifdef JS_CODEGEN_RISCV64
+        case 0b00010: {  // RO_FCVT_L_D
+          set_rd(RoundF2IHelper<int64_t>(original_val, instr_.RoundMode()));
+          break;
+        }
+        case 0b00011: {  // RO_FCVT_LU_D
+          set_rd(RoundF2IHelper<uint64_t>(original_val, instr_.RoundMode()));
+          break;
+        }
+#  endif /* JS_CODEGEN_RISCV64 */
+        default: {
+          UNSUPPORTED();
+        }
+      }
+      break;
+    }
+    case RO_FCVT_D_W: {  // RO_FCVT_D_WU , 64F RO_FCVT_D_L RO_FCVT_D_LU
+      switch (instr_.Rs2Value()) {
+        case 0b00000: {  // RO_FCVT_D_W
+          set_drd((int32_t)rs1());
+          break;
+        }
+        case 0b00001: {  // RO_FCVT_D_WU
+          set_drd((uint32_t)rs1());
+          break;
+        }
+#  ifdef JS_CODEGEN_RISCV64
+        case 0b00010: {  // RO_FCVT_D_L
+          set_drd((int64_t)rs1());
+          break;
+        }
+        case 0b00011: {  // RO_FCVT_D_LU
+          set_drd((uint64_t)rs1());
+          break;
+        }
+#  endif /* JS_CODEGEN_RISCV64 */
+        default: {
+          UNSUPPORTED();
+        }
+      }
+      break;
+    }
+#  ifdef JS_CODEGEN_RISCV64
+    case RO_FMV_D_X: {
+      if (instr_.Funct3Value() == 0b000 && instr_.Rs2Value() == 0b00000) {
+        // Since FMV preserves source bit-pattern, no need to canonize
+        set_drd(bit_cast<double>(rs1()));
+      } else {
+        UNSUPPORTED();
+      }
+      break;
+    }
+#  endif /* JS_CODEGEN_RISCV64 */
+    default: {
+      UNSUPPORTED();
+    }
+  }
+}
+
+void Simulator::DecodeRVR4Type() {
+  switch (instr_.InstructionBits() & kR4TypeMask) {
+    // TODO(riscv): use F Extension macro block
+    case RO_FMADD_S: {
+      // TODO(riscv): use rm value (round mode)
+      auto fn = [this](float frs1, float frs2, float frs3) {
+        if (is_invalid_fmul(frs1, frs2) || is_invalid_fadd(frs1 * frs2, frs3)) {
+          this->set_fflags(kInvalidOperation);
+          return std::numeric_limits<float>::quiet_NaN();
+        } else {
+          return std::fma(frs1, frs2, frs3);
+        }
+      };
+      set_frd(CanonicalizeFPUOp3<float>(fn));
+      break;
+    }
+    case RO_FMSUB_S: {
+      // TODO(riscv): use rm value (round mode)
+      auto fn = [this](float frs1, float frs2, float frs3) {
+        if (is_invalid_fmul(frs1, frs2) || is_invalid_fsub(frs1 * frs2, frs3)) {
+          this->set_fflags(kInvalidOperation);
+          return std::numeric_limits<float>::quiet_NaN();
+        } else {
+          return std::fma(frs1, frs2, -frs3);
+        }
+      };
+      set_frd(CanonicalizeFPUOp3<float>(fn));
+      break;
+    }
+    case RO_FNMSUB_S: {
+      // TODO(riscv): use rm value (round mode)
+      auto fn = [this](float frs1, float frs2, float frs3) {
+        if (is_invalid_fmul(frs1, frs2) || is_invalid_fsub(frs3, frs1 * frs2)) {
+          this->set_fflags(kInvalidOperation);
+          return std::numeric_limits<float>::quiet_NaN();
+        } else {
+          return -std::fma(frs1, frs2, -frs3);
+        }
+      };
+      set_frd(CanonicalizeFPUOp3<float>(fn));
+      break;
+    }
+    case RO_FNMADD_S: {
+      // TODO(riscv): use rm value (round mode)
+      auto fn = [this](float frs1, float frs2, float frs3) {
+        if (is_invalid_fmul(frs1, frs2) || is_invalid_fadd(frs1 * frs2, frs3)) {
+          this->set_fflags(kInvalidOperation);
+          return std::numeric_limits<float>::quiet_NaN();
+        } else {
+          return -std::fma(frs1, frs2, frs3);
+        }
+      };
+      set_frd(CanonicalizeFPUOp3<float>(fn));
+      break;
+    }
+    // TODO(riscv): use F Extension macro block
+    case RO_FMADD_D: {
+      // TODO(riscv): use rm value (round mode)
+      auto fn = [this](double drs1, double drs2, double drs3) {
+        if (is_invalid_fmul(drs1, drs2) || is_invalid_fadd(drs1 * drs2, drs3)) {
+          this->set_fflags(kInvalidOperation);
+          return std::numeric_limits<double>::quiet_NaN();
+        } else {
+          return std::fma(drs1, drs2, drs3);
+        }
+      };
+      set_drd(CanonicalizeFPUOp3<double>(fn));
+      break;
+    }
+    case RO_FMSUB_D: {
+      // TODO(riscv): use rm value (round mode)
+      auto fn = [this](double drs1, double drs2, double drs3) {
+        if (is_invalid_fmul(drs1, drs2) || is_invalid_fsub(drs1 * drs2, drs3)) {
+          this->set_fflags(kInvalidOperation);
+          return std::numeric_limits<double>::quiet_NaN();
+        } else {
+          return std::fma(drs1, drs2, -drs3);
+        }
+      };
+      set_drd(CanonicalizeFPUOp3<double>(fn));
+      break;
+    }
+    case RO_FNMSUB_D: {
+      // TODO(riscv): use rm value (round mode)
+      auto fn = [this](double drs1, double drs2, double drs3) {
+        if (is_invalid_fmul(drs1, drs2) || is_invalid_fsub(drs3, drs1 * drs2)) {
+          this->set_fflags(kInvalidOperation);
+          return std::numeric_limits<double>::quiet_NaN();
+        } else {
+          return -std::fma(drs1, drs2, -drs3);
+        }
+      };
+      set_drd(CanonicalizeFPUOp3<double>(fn));
+      break;
+    }
+    case RO_FNMADD_D: {
+      // TODO(riscv): use rm value (round mode)
+      auto fn = [this](double drs1, double drs2, double drs3) {
+        if (is_invalid_fmul(drs1, drs2) || is_invalid_fadd(drs1 * drs2, drs3)) {
+          this->set_fflags(kInvalidOperation);
+          return std::numeric_limits<double>::quiet_NaN();
+        } else {
+          return -std::fma(drs1, drs2, drs3);
+        }
+      };
+      set_drd(CanonicalizeFPUOp3<double>(fn));
+      break;
+    }
+    default:
+      UNSUPPORTED();
+  }
+}
+
+#  ifdef CAN_USE_RVV_INSTRUCTIONS
+bool Simulator::DecodeRvvVL() {
+  uint32_t instr_temp =
+      instr_.InstructionBits() & (kRvvMopMask | kRvvNfMask | kBaseOpcodeMask);
+  if (RO_V_VL == instr_temp) {
+    if (!(instr_.InstructionBits() & (kRvvRs2Mask))) {
+      switch (instr_.vl_vs_width()) {
+        case 8: {
+          RVV_VI_LD(0, (i * nf + fn), int8, false);
+          break;
+        }
+        case 16: {
+          RVV_VI_LD(0, (i * nf + fn), int16, false);
+          break;
+        }
+        case 32: {
+          RVV_VI_LD(0, (i * nf + fn), int32, false);
+          break;
+        }
+        case 64: {
+          RVV_VI_LD(0, (i * nf + fn), int64, false);
+          break;
+        }
+        default:
+          UNIMPLEMENTED_RISCV();
+          break;
+      }
+      return true;
+    } else {
+      UNIMPLEMENTED_RISCV();
+      return true;
+    }
+  } else if (RO_V_VLS == instr_temp) {
+    UNIMPLEMENTED_RISCV();
+    return true;
+  } else if (RO_V_VLX == instr_temp) {
+    UNIMPLEMENTED_RISCV();
+    return true;
+  } else if (RO_V_VLSEG2 == instr_temp || RO_V_VLSEG3 == instr_temp ||
+             RO_V_VLSEG4 == instr_temp || RO_V_VLSEG5 == instr_temp ||
+             RO_V_VLSEG6 == instr_temp || RO_V_VLSEG7 == instr_temp ||
+             RO_V_VLSEG8 == instr_temp) {
+    if (!(instr_.InstructionBits() & (kRvvRs2Mask))) {
+      UNIMPLEMENTED_RISCV();
+      return true;
+    } else {
+      UNIMPLEMENTED_RISCV();
+      return true;
+    }
+  } else if (RO_V_VLSSEG2 == instr_temp || RO_V_VLSSEG3 == instr_temp ||
+             RO_V_VLSSEG4 == instr_temp || RO_V_VLSSEG5 == instr_temp ||
+             RO_V_VLSSEG6 == instr_temp || RO_V_VLSSEG7 == instr_temp ||
+             RO_V_VLSSEG8 == instr_temp) {
+    UNIMPLEMENTED_RISCV();
+    return true;
+  } else if (RO_V_VLXSEG2 == instr_temp || RO_V_VLXSEG3 == instr_temp ||
+             RO_V_VLXSEG4 == instr_temp || RO_V_VLXSEG5 == instr_temp ||
+             RO_V_VLXSEG6 == instr_temp || RO_V_VLXSEG7 == instr_temp ||
+             RO_V_VLXSEG8 == instr_temp) {
+    UNIMPLEMENTED_RISCV();
+    return true;
+  } else {
+    return false;
+  }
+}
+
+bool Simulator::DecodeRvvVS() {
+  uint32_t instr_temp =
+      instr_.InstructionBits() & (kRvvMopMask | kRvvNfMask | kBaseOpcodeMask);
+  if (RO_V_VS == instr_temp) {
+    if (!(instr_.InstructionBits() & (kRvvRs2Mask))) {
+      switch (instr_.vl_vs_width()) {
+        case 8: {
+          RVV_VI_ST(0, (i * nf + fn), uint8, false);
+          break;
+        }
+        case 16: {
+          RVV_VI_ST(0, (i * nf + fn), uint16, false);
+          break;
+        }
+        case 32: {
+          RVV_VI_ST(0, (i * nf + fn), uint32, false);
+          break;
+        }
+        case 64: {
+          RVV_VI_ST(0, (i * nf + fn), uint64, false);
+          break;
+        }
+        default:
+          UNIMPLEMENTED_RISCV();
+          break;
+      }
+    } else {
+      UNIMPLEMENTED_RISCV();
+    }
+    return true;
+  } else if (RO_V_VSS == instr_temp) {
+    UNIMPLEMENTED_RISCV();
+    return true;
+  } else if (RO_V_VSX == instr_temp) {
+    UNIMPLEMENTED_RISCV();
+    return true;
+  } else if (RO_V_VSU == instr_temp) {
+    UNIMPLEMENTED_RISCV();
+    return true;
+  } else if (RO_V_VSSEG2 == instr_temp || RO_V_VSSEG3 == instr_temp ||
+             RO_V_VSSEG4 == instr_temp || RO_V_VSSEG5 == instr_temp ||
+             RO_V_VSSEG6 == instr_temp || RO_V_VSSEG7 == instr_temp ||
+             RO_V_VSSEG8 == instr_temp) {
+    UNIMPLEMENTED_RISCV();
+    return true;
+  } else if (RO_V_VSSSEG2 == instr_temp || RO_V_VSSSEG3 == instr_temp ||
+             RO_V_VSSSEG4 == instr_temp || RO_V_VSSSEG5 == instr_temp ||
+             RO_V_VSSSEG6 == instr_temp || RO_V_VSSSEG7 == instr_temp ||
+             RO_V_VSSSEG8 == instr_temp) {
+    UNIMPLEMENTED_RISCV();
+    return true;
+  } else if (RO_V_VSXSEG2 == instr_temp || RO_V_VSXSEG3 == instr_temp ||
+             RO_V_VSXSEG4 == instr_temp || RO_V_VSXSEG5 == instr_temp ||
+             RO_V_VSXSEG6 == instr_temp || RO_V_VSXSEG7 == instr_temp ||
+             RO_V_VSXSEG8 == instr_temp) {
+    UNIMPLEMENTED_RISCV();
+    return true;
+  } else {
+    return false;
+  }
+}
+#  endif
+
+void Simulator::DecodeRVIType() {
+  switch (instr_.InstructionBits() & kITypeMask) {
+    case RO_JALR: {
+      set_rd(get_pc() + kInstrSize);
+      // Note: No need to shift 2 for JALR's imm12, but set lowest bit to 0.
+      sreg_t next_pc = (rs1() + imm12()) & ~sreg_t(1);
+      set_pc(next_pc);
+      break;
+    }
+    case RO_LB: {
+      sreg_t addr = rs1() + imm12();
+      int8_t val = ReadMem<int8_t>(addr, instr_.instr());
+      set_rd(sext_xlen(val), false);
+      TraceMemRd(addr, val, getRegister(rd_reg()));
+      break;
+    }
+    case RO_LH: {
+      sreg_t addr = rs1() + imm12();
+      int16_t val = ReadMem<int16_t>(addr, instr_.instr());
+      set_rd(sext_xlen(val), false);
+      TraceMemRd(addr, val, getRegister(rd_reg()));
+      break;
+    }
+    case RO_LW: {
+      sreg_t addr = rs1() + imm12();
+      int32_t val = ReadMem<int32_t>(addr, instr_.instr());
+      set_rd(sext_xlen(val), false);
+      TraceMemRd(addr, val, getRegister(rd_reg()));
+      break;
+    }
+    case RO_LBU: {
+      sreg_t addr = rs1() + imm12();
+      uint8_t val = ReadMem<uint8_t>(addr, instr_.instr());
+      set_rd(zext_xlen(val), false);
+      TraceMemRd(addr, val, getRegister(rd_reg()));
+      break;
+    }
+    case RO_LHU: {
+      sreg_t addr = rs1() + imm12();
+      uint16_t val = ReadMem<uint16_t>(addr, instr_.instr());
+      set_rd(zext_xlen(val), false);
+      TraceMemRd(addr, val, getRegister(rd_reg()));
+      break;
+    }
+#  ifdef JS_CODEGEN_RISCV64
+    case RO_LWU: {
+      int64_t addr = rs1() + imm12();
+      uint32_t val = ReadMem<uint32_t>(addr, instr_.instr());
+      set_rd(zext_xlen(val), false);
+      TraceMemRd(addr, val, getRegister(rd_reg()));
+      break;
+    }
+    case RO_LD: {
+      int64_t addr = rs1() + imm12();
+      int64_t val = ReadMem<int64_t>(addr, instr_.instr());
+      set_rd(sext_xlen(val), false);
+      TraceMemRd(addr, val, getRegister(rd_reg()));
+      break;
+    }
+#  endif /*JS_CODEGEN_RISCV64*/
+    case RO_ADDI: {
+      set_rd(sext_xlen(rs1() + imm12()));
+      break;
+    }
+    case RO_SLTI: {
+      set_rd(sreg_t(rs1()) < sreg_t(imm12()));
+      break;
+    }
+    case RO_SLTIU: {
+      set_rd(reg_t(rs1()) < reg_t(imm12()));
+      break;
+    }
+    case RO_XORI: {
+      set_rd(imm12() ^ rs1());
+      break;
+    }
+    case RO_ORI: {
+      set_rd(imm12() | rs1());
+      break;
+    }
+    case RO_ANDI: {
+      set_rd(imm12() & rs1());
+      break;
+    }
+    case RO_SLLI: {
+      require(shamt6() < xlen);
+      set_rd(sext_xlen(rs1() << shamt6()));
+      break;
+    }
+    case RO_SRLI: {  //  RO_SRAI
+      if (!instr_.IsArithShift()) {
+        require(shamt6() < xlen);
+        set_rd(sext_xlen(zext_xlen(rs1()) >> shamt6()));
+      } else {
+        require(shamt6() < xlen);
+        set_rd(sext_xlen(sext_xlen(rs1()) >> shamt6()));
+      }
+      break;
+    }
+#  ifdef JS_CODEGEN_RISCV64
+    case RO_ADDIW: {
+      set_rd(sext32(rs1() + imm12()));
+      break;
+    }
+    case RO_SLLIW: {
+      set_rd(sext32(rs1() << shamt5()));
+      break;
+    }
+    case RO_SRLIW: {  //  RO_SRAIW
+      if (!instr_.IsArithShift()) {
+        set_rd(sext32(uint32_t(rs1()) >> shamt5()));
+      } else {
+        set_rd(sext32(int32_t(rs1()) >> shamt5()));
+      }
+      break;
+    }
+#  endif /*JS_CODEGEN_RISCV64*/
+    case RO_FENCE: {
+      // DO nothing in sumulator
+      break;
+    }
+    case RO_ECALL: {                   // RO_EBREAK
+      if (instr_.Imm12Value() == 0) {  // ECALL
+        SoftwareInterrupt();
+      } else if (instr_.Imm12Value() == 1) {  // EBREAK
+        uint8_t code = get_ebreak_code(instr_.instr());
+        if (code == kWasmTrapCode) {
+          HandleWasmTrap();
+        }
+        SoftwareInterrupt();
+      } else {
+        UNSUPPORTED();
+      }
+      break;
+    }
+      // TODO(riscv): use Zifencei Standard Extension macro block
+    case RO_FENCE_I: {
+      // spike: flush icache.
+      break;
+    }
+      // TODO(riscv): use Zicsr Standard Extension macro block
+    case RO_CSRRW: {
+      if (rd_reg() != zero_reg) {
+        set_rd(zext_xlen(read_csr_value(csr_reg())));
+      }
+      write_csr_value(csr_reg(), rs1());
+      break;
+    }
+    case RO_CSRRS: {
+      set_rd(zext_xlen(read_csr_value(csr_reg())));
+      if (rs1_reg() != zero_reg) {
+        set_csr_bits(csr_reg(), rs1());
+      }
+      break;
+    }
+    case RO_CSRRC: {
+      set_rd(zext_xlen(read_csr_value(csr_reg())));
+      if (rs1_reg() != zero_reg) {
+        clear_csr_bits(csr_reg(), rs1());
+      }
+      break;
+    }
+    case RO_CSRRWI: {
+      if (rd_reg() != zero_reg) {
+        set_rd(zext_xlen(read_csr_value(csr_reg())));
+      }
+      if (csr_reg() == csr_cycle) {
+        if (imm5CSR() == kWasmTrapCode) {
+          HandleWasmTrap();
+          return;
+        }
+      }
+      write_csr_value(csr_reg(), imm5CSR());
+      break;
+    }
+    case RO_CSRRSI: {
+      set_rd(zext_xlen(read_csr_value(csr_reg())));
+      if (imm5CSR() != 0) {
+        set_csr_bits(csr_reg(), imm5CSR());
+      }
+      break;
+    }
+    case RO_CSRRCI: {
+      set_rd(zext_xlen(read_csr_value(csr_reg())));
+      if (imm5CSR() != 0) {
+        clear_csr_bits(csr_reg(), imm5CSR());
+      }
+      break;
+    }
+    // TODO(riscv): use F Extension macro block
+    case RO_FLW: {
+      sreg_t addr = rs1() + imm12();
+      uint32_t val = ReadMem<uint32_t>(addr, instr_.instr());
+      set_frd(Float32::FromBits(val), false);
+      TraceMemRdFloat(addr, Float32::FromBits(val), getFpuRegister(frd_reg()));
+      break;
+    }
+    // TODO(riscv): use D Extension macro block
+    case RO_FLD: {
+      sreg_t addr = rs1() + imm12();
+      uint64_t val = ReadMem<uint64_t>(addr, instr_.instr());
+      set_drd(Float64::FromBits(val), false);
+      TraceMemRdDouble(addr, Float64::FromBits(val), getFpuRegister(frd_reg()));
+      break;
+    }
+    default: {
+#  ifdef CAN_USE_RVV_INSTRUCTIONS
+      if (!DecodeRvvVL()) {
+        UNSUPPORTED();
+      }
+      break;
+#  else
+      UNSUPPORTED();
+#  endif
+    }
+  }
+}
+
+void Simulator::DecodeRVSType() {
+  switch (instr_.InstructionBits() & kSTypeMask) {
+    case RO_SB:
+      WriteMem<uint8_t>(rs1() + s_imm12(), (uint8_t)rs2(), instr_.instr());
+      break;
+    case RO_SH:
+      WriteMem<uint16_t>(rs1() + s_imm12(), (uint16_t)rs2(), instr_.instr());
+      break;
+    case RO_SW:
+      WriteMem<uint32_t>(rs1() + s_imm12(), (uint32_t)rs2(), instr_.instr());
+      break;
+#  ifdef JS_CODEGEN_RISCV64
+    case RO_SD:
+      WriteMem<uint64_t>(rs1() + s_imm12(), (uint64_t)rs2(), instr_.instr());
+      break;
+#  endif /*JS_CODEGEN_RISCV64*/
+    // TODO(riscv): use F Extension macro block
+    case RO_FSW: {
+      WriteMem<Float32>(rs1() + s_imm12(), getFpuRegisterFloat32(rs2_reg()),
+                        instr_.instr());
+      break;
+    }
+    // TODO(riscv): use D Extension macro block
+    case RO_FSD: {
+      WriteMem<Float64>(rs1() + s_imm12(), getFpuRegisterFloat64(rs2_reg()),
+                        instr_.instr());
+      break;
+    }
+    default:
+#  ifdef CAN_USE_RVV_INSTRUCTIONS
+      if (!DecodeRvvVS()) {
+        UNSUPPORTED();
+      }
+      break;
+#  else
+      UNSUPPORTED();
+#  endif
+  }
+}
+
+void Simulator::DecodeRVBType() {
+  switch (instr_.InstructionBits() & kBTypeMask) {
+    case RO_BEQ:
+      if (rs1() == rs2()) {
+        int64_t next_pc = get_pc() + boffset();
+        set_pc(next_pc);
+      }
+      break;
+    case RO_BNE:
+      if (rs1() != rs2()) {
+        int64_t next_pc = get_pc() + boffset();
+        set_pc(next_pc);
+      }
+      break;
+    case RO_BLT:
+      if (rs1() < rs2()) {
+        int64_t next_pc = get_pc() + boffset();
+        set_pc(next_pc);
+      }
+      break;
+    case RO_BGE:
+      if (rs1() >= rs2()) {
+        int64_t next_pc = get_pc() + boffset();
+        set_pc(next_pc);
+      }
+      break;
+    case RO_BLTU:
+      if ((reg_t)rs1() < (reg_t)rs2()) {
+        int64_t next_pc = get_pc() + boffset();
+        set_pc(next_pc);
+      }
+      break;
+    case RO_BGEU:
+      if ((reg_t)rs1() >= (reg_t)rs2()) {
+        int64_t next_pc = get_pc() + boffset();
+        set_pc(next_pc);
+      }
+      break;
+    default:
+      UNSUPPORTED();
+  }
+}
+void Simulator::DecodeRVUType() {
+  // U Type doesn't have additoinal mask
+  switch (instr_.BaseOpcodeFieldRaw()) {
+    case LUI:
+      set_rd(u_imm20());
+      break;
+    case AUIPC:
+      set_rd(sext_xlen(u_imm20() + get_pc()));
+      break;
+    default:
+      UNSUPPORTED();
+  }
+}
+void Simulator::DecodeRVJType() {
+  // J Type doesn't have additional mask
+  switch (instr_.BaseOpcodeValue()) {
+    case JAL: {
+      set_rd(get_pc() + kInstrSize);
+      int64_t next_pc = get_pc() + imm20J();
+      set_pc(next_pc);
+      break;
+    }
+    default:
+      UNSUPPORTED();
+  }
+}
+void Simulator::DecodeCRType() {
+  switch (instr_.RvcFunct4Value()) {
+    case 0b1000:
+      if (instr_.RvcRs1Value() != 0 && instr_.RvcRs2Value() == 0) {  // c.jr
+        set_pc(rvc_rs1());
+      } else if (instr_.RvcRdValue() != 0 &&
+                 instr_.RvcRs2Value() != 0) {  // c.mv
+        set_rvc_rd(sext_xlen(rvc_rs2()));
+      } else {
+        UNSUPPORTED();
+      }
+      break;
+    case 0b1001:
+      if (instr_.RvcRs1Value() == 0 && instr_.RvcRs2Value() == 0) {  // c.ebreak
+        DieOrDebug();
+      } else if (instr_.RvcRdValue() != 0 &&
+                 instr_.RvcRs2Value() == 0) {  // c.jalr
+        setRegister(ra, get_pc() + kShortInstrSize);
+        set_pc(rvc_rs1());
+      } else if (instr_.RvcRdValue() != 0 &&
+                 instr_.RvcRs2Value() != 0) {  // c.add
+        set_rvc_rd(sext_xlen(rvc_rs1() + rvc_rs2()));
+      } else {
+        UNSUPPORTED();
+      }
+      break;
+    default:
+      UNSUPPORTED();
+  }
+}
+
+void Simulator::DecodeCAType() {
+  switch (instr_.InstructionBits() & kCATypeMask) {
+    case RO_C_SUB:
+      set_rvc_rs1s(sext_xlen(rvc_rs1s() - rvc_rs2s()));
+      break;
+    case RO_C_XOR:
+      set_rvc_rs1s(rvc_rs1s() ^ rvc_rs2s());
+      break;
+    case RO_C_OR:
+      set_rvc_rs1s(rvc_rs1s() | rvc_rs2s());
+      break;
+    case RO_C_AND:
+      set_rvc_rs1s(rvc_rs1s() & rvc_rs2s());
+      break;
+#  if JS_CODEGEN_RISCV64
+    case RO_C_SUBW:
+      set_rvc_rs1s(sext32(rvc_rs1s() - rvc_rs2s()));
+      break;
+    case RO_C_ADDW:
+      set_rvc_rs1s(sext32(rvc_rs1s() + rvc_rs2s()));
+      break;
+#  endif
+    default:
+      UNSUPPORTED();
+  }
+}
+
+void Simulator::DecodeCIType() {
+  switch (instr_.RvcOpcode()) {
+    case RO_C_NOP_ADDI:
+      if (instr_.RvcRdValue() == 0)  // c.nop
+        break;
+      else  // c.addi
+        set_rvc_rd(sext_xlen(rvc_rs1() + rvc_imm6()));
+      break;
+#  if JS_CODEGEN_RISCV64
+    case RO_C_ADDIW:
+      set_rvc_rd(sext32(rvc_rs1() + rvc_imm6()));
+      break;
+#  endif
+    case RO_C_LI:
+      set_rvc_rd(sext_xlen(rvc_imm6()));
+      break;
+    case RO_C_LUI_ADD:
+      if (instr_.RvcRdValue() == 2) {
+        // c.addi16sp
+        int64_t value = getRegister(sp) + rvc_imm6_addi16sp();
+        setRegister(sp, value);
+      } else if (instr_.RvcRdValue() != 0 && instr_.RvcRdValue() != 2) {
+        // c.lui
+        set_rvc_rd(rvc_u_imm6());
+      } else {
+        UNSUPPORTED();
+      }
+      break;
+    case RO_C_SLLI:
+      set_rvc_rd(sext_xlen(rvc_rs1() << rvc_shamt6()));
+      break;
+    case RO_C_FLDSP: {
+      sreg_t addr = getRegister(sp) + rvc_imm6_ldsp();
+      uint64_t val = ReadMem<uint64_t>(addr, instr_.instr());
+      set_rvc_drd(Float64::FromBits(val), false);
+      TraceMemRdDouble(addr, Float64::FromBits(val),
+                       getFpuRegister(rvc_frd_reg()));
+      break;
+    }
+#  if JS_CODEGEN_RISCV64
+    case RO_C_LWSP: {
+      sreg_t addr = getRegister(sp) + rvc_imm6_lwsp();
+      int64_t val = ReadMem<int32_t>(addr, instr_.instr());
+      set_rvc_rd(sext_xlen(val), false);
+      TraceMemRd(addr, val, getRegister(rvc_rd_reg()));
+      break;
+    }
+    case RO_C_LDSP: {
+      sreg_t addr = getRegister(sp) + rvc_imm6_ldsp();
+      int64_t val = ReadMem<int64_t>(addr, instr_.instr());
+      set_rvc_rd(sext_xlen(val), false);
+      TraceMemRd(addr, val, getRegister(rvc_rd_reg()));
+      break;
+    }
+#  elif JS_CODEGEN_RISCV32
+    case RO_C_FLWSP: {
+      sreg_t addr = getRegister(sp) + rvc_imm6_ldsp();
+      uint32_t val = ReadMem<uint32_t>(addr, instr_.instr());
+      set_rvc_frd(Float32::FromBits(val), false);
+      TraceMemRdFloat(addr, Float32::FromBits(val),
+                      getFpuRegister(rvc_frd_reg()));
+      break;
+    }
+    case RO_C_LWSP: {
+      sreg_t addr = getRegister(sp) + rvc_imm6_lwsp();
+      int32_t val = ReadMem<int32_t>(addr, instr_.instr());
+      set_rvc_rd(sext_xlen(val), false);
+      TraceMemRd(addr, val, getRegister(rvc_rd_reg()));
+      break;
+    }
+#  endif
+    default:
+      UNSUPPORTED();
+  }
+}
+
+void Simulator::DecodeCIWType() {
+  switch (instr_.RvcOpcode()) {
+    case RO_C_ADDI4SPN: {
+      set_rvc_rs2s(getRegister(sp) + rvc_imm8_addi4spn());
+      break;
+      default:
+        UNSUPPORTED();
+    }
+  }
+}
+
+void Simulator::DecodeCSSType() {
+  switch (instr_.RvcOpcode()) {
+    case RO_C_FSDSP: {
+      sreg_t addr = getRegister(sp) + rvc_imm6_sdsp();
+      WriteMem<Float64>(addr, getFpuRegisterFloat64(rvc_rs2_reg()),
+                        instr_.instr());
+      break;
+    }
+#  if JS_CODEGEN_RISCV32
+    case RO_C_FSWSP: {
+      sreg_t addr = getRegister(sp) + rvc_imm6_sdsp();
+      WriteMem<Float32>(addr, getFpuRegisterFloat32(rvc_rs2_reg()),
+                        instr_.instr());
+      break;
+    }
+#  endif
+    case RO_C_SWSP: {
+      sreg_t addr = getRegister(sp) + rvc_imm6_swsp();
+      WriteMem<int32_t>(addr, (int32_t)rvc_rs2(), instr_.instr());
+      break;
+    }
+#  if JS_CODEGEN_RISCV64
+    case RO_C_SDSP: {
+      sreg_t addr = getRegister(sp) + rvc_imm6_sdsp();
+      WriteMem<int64_t>(addr, (int64_t)rvc_rs2(), instr_.instr());
+      break;
+    }
+#  endif
+    default:
+      UNSUPPORTED();
+  }
+}
+
+void Simulator::DecodeCLType() {
+  switch (instr_.RvcOpcode()) {
+    case RO_C_LW: {
+      sreg_t addr = rvc_rs1s() + rvc_imm5_w();
+      int64_t val = ReadMem<int32_t>(addr, instr_.instr());
+      set_rvc_rs2s(sext_xlen(val), false);
+      TraceMemRd(addr, val, getRegister(rvc_rs2s_reg()));
+      break;
+    }
+    case RO_C_FLD: {
+      sreg_t addr = rvc_rs1s() + rvc_imm5_d();
+      uint64_t val = ReadMem<uint64_t>(addr, instr_.instr());
+      set_rvc_drs2s(Float64::FromBits(val), false);
+      break;
+    }
+#  if JS_CODEGEN_RISCV64
+    case RO_C_LD: {
+      sreg_t addr = rvc_rs1s() + rvc_imm5_d();
+      int64_t val = ReadMem<int64_t>(addr, instr_.instr());
+      set_rvc_rs2s(sext_xlen(val), false);
+      TraceMemRd(addr, val, getRegister(rvc_rs2s_reg()));
+      break;
+    }
+#  elif JS_CODEGEN_RISCV32
+    case RO_C_FLW: {
+      sreg_t addr = rvc_rs1s() + rvc_imm5_d();
+      uint32_t val = ReadMem<uint32_t>(addr, instr_.instr());
+      set_rvc_frs2s(Float32::FromBits(val), false);
+      break;
+    }
+#  endif
+    default:
+      UNSUPPORTED();
+  }
+}
+
+void Simulator::DecodeCSType() {
+  switch (instr_.RvcOpcode()) {
+    case RO_C_SW: {
+      sreg_t addr = rvc_rs1s() + rvc_imm5_w();
+      WriteMem<int32_t>(addr, (int32_t)rvc_rs2s(), instr_.instr());
+      break;
+    }
+#  if JS_CODEGEN_RISCV64
+    case RO_C_SD: {
+      sreg_t addr = rvc_rs1s() + rvc_imm5_d();
+      WriteMem<int64_t>(addr, (int64_t)rvc_rs2s(), instr_.instr());
+      break;
+    }
+#  endif
+    case RO_C_FSD: {
+      sreg_t addr = rvc_rs1s() + rvc_imm5_d();
+      WriteMem<double>(addr, static_cast<double>(rvc_drs2s()), instr_.instr());
+      break;
+    }
+    default:
+      UNSUPPORTED();
+  }
+}
+
+void Simulator::DecodeCJType() {
+  switch (instr_.RvcOpcode()) {
+    case RO_C_J: {
+      set_pc(get_pc() + instr_.RvcImm11CJValue());
+      break;
+    }
+    default:
+      UNSUPPORTED();
+  }
+}
+
+void Simulator::DecodeCBType() {
+  switch (instr_.RvcOpcode()) {
+    case RO_C_BNEZ:
+      if (rvc_rs1() != 0) {
+        sreg_t next_pc = get_pc() + rvc_imm8_b();
+        set_pc(next_pc);
+      }
+      break;
+    case RO_C_BEQZ:
+      if (rvc_rs1() == 0) {
+        sreg_t next_pc = get_pc() + rvc_imm8_b();
+        set_pc(next_pc);
+      }
+      break;
+    case RO_C_MISC_ALU:
+      if (instr_.RvcFunct2BValue() == 0b00) {  // c.srli
+        set_rvc_rs1s(sext_xlen(sext_xlen(rvc_rs1s()) >> rvc_shamt6()));
+      } else if (instr_.RvcFunct2BValue() == 0b01) {  // c.srai
+        require(rvc_shamt6() < xlen);
+        set_rvc_rs1s(sext_xlen(sext_xlen(rvc_rs1s()) >> rvc_shamt6()));
+      } else if (instr_.RvcFunct2BValue() == 0b10) {  // c.andi
+        set_rvc_rs1s(rvc_imm6() & rvc_rs1s());
+      } else {
+        UNSUPPORTED();
+      }
+      break;
+    default:
+      UNSUPPORTED();
+  }
+}
+
+void Simulator::callInternal(uint8_t* entry) {
+  // Prepare to execute the code at entry.
+  setRegister(pc, reinterpret_cast<int64_t>(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.
+  setRegister(ra, end_sim_pc);
+  // Remember the values of callee-saved registers.
+  intptr_t s0_val = getRegister(Simulator::Register::fp);
+  intptr_t s1_val = getRegister(Simulator::Register::s1);
+  intptr_t s2_val = getRegister(Simulator::Register::s2);
+  intptr_t s3_val = getRegister(Simulator::Register::s3);
+  intptr_t s4_val = getRegister(Simulator::Register::s4);
+  intptr_t s5_val = getRegister(Simulator::Register::s5);
+  intptr_t s6_val = getRegister(Simulator::Register::s6);
+  intptr_t s7_val = getRegister(Simulator::Register::s7);
+  intptr_t s8_val = getRegister(Simulator::Register::s8);
+  intptr_t s9_val = getRegister(Simulator::Register::s9);
+  intptr_t s10_val = getRegister(Simulator::Register::s10);
+  intptr_t s11_val = getRegister(Simulator::Register::s11);
+  intptr_t gp_val = getRegister(Simulator::Register::gp);
+  intptr_t sp_val = getRegister(Simulator::Register::sp);
+
+  // Set up the callee-saved registers with a known value. To be able to check
+  // that they are preserved properly across JS execution. If this value is
+  // small int, it should be SMI.
+  intptr_t callee_saved_value = icount_;
+  setRegister(Simulator::Register::fp, callee_saved_value);
+  setRegister(Simulator::Register::s1, callee_saved_value);
+  setRegister(Simulator::Register::s2, callee_saved_value);
+  setRegister(Simulator::Register::s3, callee_saved_value);
+  setRegister(Simulator::Register::s4, callee_saved_value);
+  setRegister(Simulator::Register::s5, callee_saved_value);
+  setRegister(Simulator::Register::s6, callee_saved_value);
+  setRegister(Simulator::Register::s7, callee_saved_value);
+  setRegister(Simulator::Register::s8, callee_saved_value);
+  setRegister(Simulator::Register::s9, callee_saved_value);
+  setRegister(Simulator::Register::s10, callee_saved_value);
+  setRegister(Simulator::Register::s11, callee_saved_value);
+  setRegister(Simulator::Register::gp, callee_saved_value);
+
+  // Start the simulation.
+  if (Simulator::StopSimAt != -1) {
+    execute<true>();
+  } else {
+    execute<false>();
+  }
+
+  // Check that the callee-saved registers have been preserved.
+  MOZ_ASSERT(callee_saved_value == getRegister(Simulator::Register::fp));
+  MOZ_ASSERT(callee_saved_value == getRegister(Simulator::Register::s1));
+  MOZ_ASSERT(callee_saved_value == getRegister(Simulator::Register::s2));
+  MOZ_ASSERT(callee_saved_value == getRegister(Simulator::Register::s3));
+  MOZ_ASSERT(callee_saved_value == getRegister(Simulator::Register::s4));
+  MOZ_ASSERT(callee_saved_value == getRegister(Simulator::Register::s5));
+  MOZ_ASSERT(callee_saved_value == getRegister(Simulator::Register::s6));
+  MOZ_ASSERT(callee_saved_value == getRegister(Simulator::Register::s7));
+  MOZ_ASSERT(callee_saved_value == getRegister(Simulator::Register::s8));
+  MOZ_ASSERT(callee_saved_value == getRegister(Simulator::Register::s9));
+  MOZ_ASSERT(callee_saved_value == getRegister(Simulator::Register::s10));
+  MOZ_ASSERT(callee_saved_value == getRegister(Simulator::Register::s11));
+  MOZ_ASSERT(callee_saved_value == getRegister(Simulator::Register::gp));
+
+  // Restore callee-saved registers with the original value.
+  setRegister(Simulator::Register::fp, s0_val);
+  setRegister(Simulator::Register::s1, s1_val);
+  setRegister(Simulator::Register::s2, s2_val);
+  setRegister(Simulator::Register::s3, s3_val);
+  setRegister(Simulator::Register::s4, s4_val);
+  setRegister(Simulator::Register::s5, s5_val);
+  setRegister(Simulator::Register::s6, s6_val);
+  setRegister(Simulator::Register::s7, s7_val);
+  setRegister(Simulator::Register::s8, s8_val);
+  setRegister(Simulator::Register::s9, s9_val);
+  setRegister(Simulator::Register::s10, s10_val);
+  setRegister(Simulator::Register::s11, s11_val);
+  setRegister(Simulator::Register::gp, gp_val);
+  setRegister(Simulator::Register::sp, sp_val);
+}
+
+int64_t Simulator::call(uint8_t* entry, int argument_count, ...) {
+  va_list parameters;
+  va_start(parameters, argument_count);
+
+  int64_t original_stack = getRegister(sp);
+  // Compute position of stack on entry to generated code.
+  int64_t entry_stack = original_stack;
+  if (argument_count > kCArgSlotCount) {
+    entry_stack = entry_stack - argument_count * sizeof(int64_t);
+  } else {
+    entry_stack = entry_stack - kCArgsSlotsSize;
+  }
+
+  entry_stack &= ~U64(ABIStackAlignment - 1);
+
+  intptr_t* stack_argument = reinterpret_cast<intptr_t*>(entry_stack);
+
+  // Setup the arguments.
+  for (int i = 0; i < argument_count; i++) {
+    js::jit::Register argReg;
+    if (GetIntArgReg(i, &argReg)) {
+      setRegister(argReg.code(), va_arg(parameters, int64_t));
+    } else {
+      stack_argument[i] = va_arg(parameters, int64_t);
+    }
+  }
+
+  va_end(parameters);
+  setRegister(sp, entry_stack);
+
+  callInternal(entry);
+
+  // Pop stack passed arguments.
+  MOZ_ASSERT(entry_stack == getRegister(sp));
+  setRegister(sp, original_stack);
+
+  int64_t result = getRegister(a0);
+  return result;
+}
+
+uintptr_t Simulator::pushAddress(uintptr_t address) {
+  int new_sp = getRegister(sp) - sizeof(uintptr_t);
+  uintptr_t* stack_slot = reinterpret_cast<uintptr_t*>(new_sp);
+  *stack_slot = address;
+  setRegister(sp, new_sp);
+  return new_sp;
+}
+
+uintptr_t Simulator::popAddress() {
+  int current_sp = getRegister(sp);
+  uintptr_t* stack_slot = reinterpret_cast<uintptr_t*>(current_sp);
+  uintptr_t address = *stack_slot;
+  setRegister(sp, current_sp + sizeof(uintptr_t));
+  return address;
+}
+
+}  // namespace jit
+}  // namespace js
+
+js::jit::Simulator* JSContext::simulator() const { return simulator_; }
+
+#endif  // JS_SIMULATOR_RISCV64