MIPS[64]: Add support for FPR content in simulator trace.

src/mips/simulator-mips.cc

 // Copyright 2011 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include <limits.h>
 #include <stdarg.h>
 #include <stdlib.h>
 #include <cmath>
 
 #if V8_TARGET_ARCH_MIPS
@@ skipping 1111 matching lines @@
   // Read the bits from the unsigned integer register_[] array
   // into the double precision floating point value and return it.
   char buffer[2 * sizeof(registers_[0])];
   memcpy(buffer, &registers_[reg], 2 * sizeof(registers_[0]));
   memcpy(&dm_val, buffer, 2 * sizeof(registers_[0]));
   return(dm_val);
 }
 
 
 int64_t Simulator::get_fpu_register(int fpureg) const {
-  DCHECK(IsFp64Mode());
-  DCHECK((fpureg >= 0) && (fpureg < kNumFPURegisters));
-  return FPUregisters_[fpureg];
+  if (IsFp64Mode()) {
+    DCHECK((fpureg >= 0) && (fpureg < kNumFPURegisters));
+    return FPUregisters_[fpureg];
+  } else {
+    DCHECK((fpureg >= 0) && (fpureg < kNumFPURegisters) && ((fpureg % 2) == 0));
+    int64_t i64;
+    i64 = static_cast<uint32_t>(get_fpu_register_word(fpureg));
+    i64 |= static_cast<uint64_t>(get_fpu_register_word(fpureg + 1)) << 32;

[ivica.bogosavljevic, 2017/01/23 13:22:38]

According to strict C/C++, bitwise operation should not be done on signed
integers. Use unsigned integers and do a static_cast to signed at the end

[Ilija.Pavlovic1, 2017/01/27 09:09:16]

Done.

+    return i64;
+  }
 }
 
 
 int32_t Simulator::get_fpu_register_word(int fpureg) const {
   DCHECK((fpureg >= 0) && (fpureg < kNumFPURegisters));
   return static_cast<int32_t>(FPUregisters_[fpureg] & 0xffffffff);
 }
 
 
 int32_t Simulator::get_fpu_register_signed_word(int fpureg) const {
@@ skipping 536 matching lines @@
 
 
 // The MIPS cannot do unaligned reads and writes.  On some MIPS platforms an
 // interrupt is caused.  On others it does a funky rotation thing.  For now we
 // simply disallow unaligned reads, but at some point we may want to move to
 // emulating the rotate behaviour.  Note that simulator runs have the runtime
 // system running directly on the host system and only generated code is
 // executed in the simulator.  Since the host is typically IA32 we will not
 // get the correct MIPS-like behaviour on unaligned accesses.
 
-void Simulator::TraceRegWr(int32_t value) {
+void Simulator::TraceRegWr(int32_t value, TraceType t) {
   if (::v8::internal::FLAG_trace_sim) {
-    SNPrintF(trace_buf_, "%08x", value);
+    union {
+      int32_t fmt_int32;
+      float fmt_float;
+    } v;
+    v.fmt_int32 = value;
+
+    switch (t) {
+      case WORD:
+        SNPrintF(trace_buf_, "%08" PRIx32 "    (%" PRIu64 ")    int32:%" PRId32
+                             " uint32:%" PRIu32,
+                 value, icount_, value, value);
+        break;
+      case FLOAT:
+        SNPrintF(trace_buf_, "%08" PRIx32 "    (%" PRIu64 ")    flt:%e",
+                 v.fmt_int32, icount_, v.fmt_float);
+      default:
+        break;

[ivica.bogosavljevic, 2017/01/23 13:22:38]

this should be UNREACHABLE, right?

[Ilija.Pavlovic1, 2017/01/27 09:09:16]

Yes, this should be UNREACHABLE(). Also, missing "break;" in "case FLOAT".

Done.

+    }
   }
 }
 
+void Simulator::TraceRegWr(int64_t value, TraceType t) {
+  if (::v8::internal::FLAG_trace_sim) {
+    union {
+      int64_t fmt_int64;
+      double fmt_double;
+    } v;
+    v.fmt_int64 = value;
 
-// TODO(plind): consider making icount_ printing a flag option.
-void Simulator::TraceMemRd(int32_t addr, int32_t value) {
-  if (::v8::internal::FLAG_trace_sim) {
-    SNPrintF(trace_buf_, "%08x <-- [%08x]    (%" PRIu64 ")", value, addr,
-             icount_);
+    switch (t) {
+      case DWORD:
+        SNPrintF(trace_buf_, "%016" PRIx64 "    (%" PRIu64 ")    int64:%" PRId64
+                             " uint64:%" PRIu64,
+                 value, icount_, value, value);
+        break;
+      case DOUBLE:
+        SNPrintF(trace_buf_, "%016" PRIx64 "    (%" PRIu64 ")    dbl:%e",
+                 v.fmt_int64, icount_, v.fmt_double);
+      default:
+        break;

[ivica.bogosavljevic, 2017/01/23 13:22:38]

UNREACHABLE!

[Ilija.Pavlovic1, 2017/01/27 09:09:16]

Done.

+    }
   }
 }
 
+// TODO(plind): consider making icount_ printing a flag option.
+void Simulator::TraceMemRd(int32_t addr, int32_t value, TraceType t) {
+  if (::v8::internal::FLAG_trace_sim) {
+    union {
+      int32_t fmt_int32;
+      float fmt_float;
+    } v;
+    v.fmt_int32 = value;
+
+    switch (t) {
+      case WORD:
+        SNPrintF(trace_buf_, "%08" PRIx32 " <-- [%08" PRIx32 "]    (%" PRIu64
+                             ")    int32:%" PRId32 " uint32:%" PRIu32,
+                 value, addr, icount_, value, value);
+        break;
+      case FLOAT:
+        SNPrintF(trace_buf_,
+                 "%08" PRIx32 " <-- [%08" PRIx32 "]    (%" PRIu64 ")    flt:%e",
+                 v.fmt_int32, addr, icount_, v.fmt_float);
+        break;
+      default:
+        break;

[ivica.bogosavljevic, 2017/01/23 13:22:38]

ibid here and all places bellow!

[Ilija.Pavlovic1, 2017/01/27 09:09:16]

Done.

+    }
+  }
+}
+
 
 void Simulator::TraceMemWr(int32_t addr, int32_t value, TraceType t) {
   if (::v8::internal::FLAG_trace_sim) {
     switch (t) {
       case BYTE:
-        SNPrintF(trace_buf_, "      %02x --> [%08x]",
-                 static_cast<int8_t>(value), addr);
+        SNPrintF(trace_buf_,
+                 "      %02" PRIx8 " --> [%08" PRIx32 "]    (%" PRIu64 ")",
+                 static_cast<uint8_t>(value), addr, icount_);
         break;
       case HALF:
-        SNPrintF(trace_buf_, "    %04x --> [%08x]", static_cast<int16_t>(value),
-                 addr);
+        SNPrintF(trace_buf_,
+                 "    %04" PRIx16 " --> [%08" PRIx32 "]    (%" PRIu64 ")",
+                 static_cast<uint16_t>(value), addr, icount_);
         break;
       case WORD:
-        SNPrintF(trace_buf_, "%08x --> [%08x]", value, addr);
+        SNPrintF(trace_buf_,
+                 "%08" PRIx32 " --> [%08" PRIx32 "]    (%" PRIu64 ")", value,
+                 addr, icount_);
+        break;
+      default:
         break;
     }
   }
 }
 
+void Simulator::TraceMemRd(int32_t addr, int64_t value, TraceType t) {
+  if (::v8::internal::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;
 
-int Simulator::ReadW(int32_t addr, Instruction* instr) {
+    switch (t) {
+      case DWORD:
+        SNPrintF(trace_buf_, "%016" PRIx64 " <-- [%08" PRIx32 "]    (%" PRIu64
+                             ")    int64:%" PRId64 " uint64:%" PRIu64,
+                 v.fmt_int64, addr, icount_, v.fmt_int64, v.fmt_int64);
+        break;
+      case DOUBLE:
+        SNPrintF(trace_buf_, "%016" PRIx64 " <-- [%08" PRIx32 "]    (%" PRIu64
+                             ")    dbl:%e",
+                 v.fmt_int64, addr, icount_, v.fmt_double);
+        break;
+      case FLOAT_DOUBLE:
+        SNPrintF(trace_buf_, "%08" PRIx32 " <-- [%08" PRIx32 "]    (%" PRIu64
+                             ")    flt:%e dbl:%e",
+                 v.fmt_int32[1], addr, icount_, v.fmt_float[1], v.fmt_double);
+        break;
+      default:
+        break;
+    }
+  }
+}
+
+void Simulator::TraceMemWr(int32_t addr, int64_t value, TraceType t) {
+  if (::v8::internal::FLAG_trace_sim) {
+    switch (t) {
+      case DWORD:
+        SNPrintF(trace_buf_,
+                 "%016" PRIx64 " --> [%08" PRIx32 "]    (%" PRIu64 ")", value,
+                 addr, icount_);
+        break;
+      default:
+        break;
+    }
+  }
+}
+
+int Simulator::ReadW(int32_t addr, Instruction* instr, TraceType t) {
   if (addr >=0 && addr < 0x400) {
     // This has to be a NULL-dereference, drop into debugger.
     PrintF("Memory read from bad address: 0x%08x, pc=0x%08" PRIxPTR "\n", addr,
            reinterpret_cast<intptr_t>(instr));
     MipsDebugger dbg(this);
     dbg.Debug();
   }
   if ((addr & kPointerAlignmentMask) == 0 || IsMipsArchVariant(kMips32r6)) {
     intptr_t* ptr = reinterpret_cast<intptr_t*>(addr);
-    TraceMemRd(addr, static_cast<int32_t>(*ptr));
+    if (t == WORD) {
+      TraceMemRd(addr, static_cast<int32_t>(*ptr), t);

[ivica.bogosavljevic, 2017/01/23 13:22:38]

What happens if t != WORD? Should it be unreachable, or some other values are
allowed? Please document!

[Ilija.Pavlovic1, 2017/01/27 09:09:16]

For WORD, the trace should be visible.
For FLOAT, the tracing will be omitted.
Other values will be UNREACHABLE.

Done.

+    }
     return *ptr;
   }
   PrintF("Unaligned read at 0x%08x, pc=0x%08" V8PRIxPTR "\n",
          addr,
          reinterpret_cast<intptr_t>(instr));
   MipsDebugger dbg(this);
   dbg.Debug();
   return 0;
 }
 
-
 void Simulator::WriteW(int32_t addr, int value, Instruction* instr) {
   if (addr >= 0 && addr < 0x400) {
     // This has to be a NULL-dereference, drop into debugger.
     PrintF("Memory write to bad address: 0x%08x, pc=0x%08" PRIxPTR "\n", addr,
            reinterpret_cast<intptr_t>(instr));
     MipsDebugger dbg(this);
     dbg.Debug();
   }
   if ((addr & kPointerAlignmentMask) == 0 || IsMipsArchVariant(kMips32r6)) {
     intptr_t* ptr = reinterpret_cast<intptr_t*>(addr);
     TraceMemWr(addr, value, WORD);
     *ptr = value;
     return;
   }
   PrintF("Unaligned write at 0x%08x, pc=0x%08" V8PRIxPTR "\n",
          addr,
          reinterpret_cast<intptr_t>(instr));
   MipsDebugger dbg(this);
   dbg.Debug();
 }
 
-
 double Simulator::ReadD(int32_t addr, Instruction* instr) {
   if ((addr & kDoubleAlignmentMask) == 0 || IsMipsArchVariant(kMips32r6)) {
     double* ptr = reinterpret_cast<double*>(addr);
     return *ptr;
   }
   PrintF("Unaligned (double) read at 0x%08x, pc=0x%08" V8PRIxPTR "\n",
          addr,
          reinterpret_cast<intptr_t>(instr));
   base::OS::Abort();
   return 0;
@@ skipping 677 matching lines @@
           result = upper;
           break;
         case kRoundToMinusInf:
           result = lower;
           break;
       }
       set_fpu_register_double(fd_reg(), result);
       if (result != fs) {
         set_fcsr_bit(kFCSRInexactFlagBit, true);
       }
+      TraceRegWr(get_fpu_register(fd_reg()), DOUBLE);
       break;
     }
     case SEL:
       DCHECK(IsMipsArchVariant(kMips32r6));
       set_fpu_register_double(fd_reg(), (fd_int & 0x1) == 0 ? fs : ft);
+      TraceRegWr(get_fpu_register(fd_reg()), DOUBLE);
       break;
     case SELEQZ_C:
       DCHECK(IsMipsArchVariant(kMips32r6));
       set_fpu_register_double(fd_reg(), (ft_int & 0x1) == 0 ? fs : 0.0);
+      TraceRegWr(get_fpu_register(fd_reg()), DOUBLE);
       break;
     case SELNEZ_C:
       DCHECK(IsMipsArchVariant(kMips32r6));
       set_fpu_register_double(fd_reg(), (ft_int & 0x1) != 0 ? fs : 0.0);
+      TraceRegWr(get_fpu_register(fd_reg()), DOUBLE);
       break;
     case MOVZ_C: {
       DCHECK(IsMipsArchVariant(kMips32r2));
       if (rt() == 0) {
         set_fpu_register_double(fd_reg(), fs);
       }
+      TraceRegWr(get_fpu_register(fd_reg()), DOUBLE);
       break;
     }
     case MOVN_C: {
       DCHECK(IsMipsArchVariant(kMips32r2));
       int32_t rt_reg = instr_.RtValue();
       int32_t rt = get_register(rt_reg);
       if (rt != 0) {
         set_fpu_register_double(fd_reg(), fs);
       }
+      TraceRegWr(get_fpu_register(fd_reg()), DOUBLE);
       break;
     }
     case MOVF: {
       // Same function field for MOVT.D and MOVF.D
       uint32_t ft_cc = (ft_reg() >> 2) & 0x7;
       ft_cc = get_fcsr_condition_bit(ft_cc);
       if (instr_.Bit(16)) {  // Read Tf bit.
         // MOVT.D
         if (test_fcsr_bit(ft_cc)) set_fpu_register_double(fd_reg(), fs);
       } else {
         // MOVF.D
         if (!test_fcsr_bit(ft_cc)) set_fpu_register_double(fd_reg(), fs);
       }
+      TraceRegWr(get_fpu_register(fd_reg()), DOUBLE);
       break;
     }
     case MIN:
       DCHECK(IsMipsArchVariant(kMips32r6));
       set_fpu_register_double(fd_reg(), FPUMin(ft, fs));
+      TraceRegWr(get_fpu_register(fd_reg()), DOUBLE);
       break;
     case MAX:
       DCHECK(IsMipsArchVariant(kMips32r6));
       set_fpu_register_double(fd_reg(), FPUMax(ft, fs));
+      TraceRegWr(get_fpu_register(fd_reg()), DOUBLE);
       break;
     case MINA:
       DCHECK(IsMipsArchVariant(kMips32r6));
       set_fpu_register_double(fd_reg(), FPUMinA(ft, fs));
+      TraceRegWr(get_fpu_register(fd_reg()), DOUBLE);
       break;
     case MAXA:
       DCHECK(IsMipsArchVariant(kMips32r6));
       set_fpu_register_double(fd_reg(), FPUMaxA(ft, fs));
+      TraceRegWr(get_fpu_register(fd_reg()), DOUBLE);
       break;
     case ADD_D:
       set_fpu_register_double(
           fd_reg(),
           FPUCanonalizeOperation(
               [](double lhs, double rhs) { return lhs + rhs; }, fs, ft));
+      TraceRegWr(get_fpu_register(fd_reg()), DOUBLE);
       break;
     case SUB_D:
       set_fpu_register_double(
           fd_reg(),
           FPUCanonalizeOperation(
               [](double lhs, double rhs) { return lhs - rhs; }, fs, ft));
+      TraceRegWr(get_fpu_register(fd_reg()), DOUBLE);
       break;
     case MADDF_D:
       DCHECK(IsMipsArchVariant(kMips32r6));
       set_fpu_register_double(fd_reg(), std::fma(fs, ft, fd));
+      TraceRegWr(get_fpu_register(fd_reg()), DOUBLE);
       break;
     case MSUBF_D:
       DCHECK(IsMipsArchVariant(kMips32r6));
       set_fpu_register_double(fd_reg(), std::fma(-fs, ft, fd));
+      TraceRegWr(get_fpu_register(fd_reg()), DOUBLE);
       break;
     case MUL_D:
       set_fpu_register_double(
           fd_reg(),
           FPUCanonalizeOperation(
               [](double lhs, double rhs) { return lhs * rhs; }, fs, ft));
+      TraceRegWr(get_fpu_register(fd_reg()), DOUBLE);
       break;
     case DIV_D:
       set_fpu_register_double(
           fd_reg(),
           FPUCanonalizeOperation(
               [](double lhs, double rhs) { return lhs / rhs; }, fs, ft));
+      TraceRegWr(get_fpu_register(fd_reg()), DOUBLE);
       break;
     case ABS_D:
       set_fpu_register_double(
           fd_reg(),
           FPUCanonalizeOperation([](double fs) { return FPAbs(fs); }, fs));
+      TraceRegWr(get_fpu_register(fd_reg()), DOUBLE);
       break;
     case MOV_D:
       set_fpu_register_double(fd_reg(), fs);
+      TraceRegWr(get_fpu_register(fd_reg()), DOUBLE);
       break;
     case NEG_D:
       set_fpu_register_double(
           fd_reg(), FPUCanonalizeOperation([](double src) { return -src; },
                                            KeepSign::yes, fs));
+      TraceRegWr(get_fpu_register(fd_reg()), DOUBLE);
       break;
     case SQRT_D:
       set_fpu_register_double(
           fd_reg(),
           FPUCanonalizeOperation([](double fs) { return std::sqrt(fs); }, fs));
+      TraceRegWr(get_fpu_register(fd_reg()), DOUBLE);
       break;
     case RSQRT_D:
       set_fpu_register_double(
           fd_reg(), FPUCanonalizeOperation(
                         [](double fs) { return 1.0 / std::sqrt(fs); }, fs));
+      TraceRegWr(get_fpu_register(fd_reg()), DOUBLE);
       break;
     case RECIP_D:
       set_fpu_register_double(
           fd_reg(),
           FPUCanonalizeOperation([](double fs) { return 1.0 / fs; }, fs));
+      TraceRegWr(get_fpu_register(fd_reg()), DOUBLE);
       break;
     case C_UN_D:
       set_fcsr_bit(fcsr_cc, std::isnan(fs) || std::isnan(ft));
+      TraceRegWr(test_fcsr_bit(fcsr_cc));
       break;
     case C_EQ_D:
       set_fcsr_bit(fcsr_cc, (fs == ft));
+      TraceRegWr(test_fcsr_bit(fcsr_cc));
       break;
     case C_UEQ_D:
       set_fcsr_bit(fcsr_cc, (fs == ft) || (std::isnan(fs) || std::isnan(ft)));
+      TraceRegWr(test_fcsr_bit(fcsr_cc));
       break;
     case C_OLT_D:
       set_fcsr_bit(fcsr_cc, (fs < ft));
+      TraceRegWr(test_fcsr_bit(fcsr_cc));
       break;
     case C_ULT_D:
       set_fcsr_bit(fcsr_cc, (fs < ft) || (std::isnan(fs) || std::isnan(ft)));
+      TraceRegWr(test_fcsr_bit(fcsr_cc));
       break;
     case C_OLE_D:
       set_fcsr_bit(fcsr_cc, (fs <= ft));
+      TraceRegWr(test_fcsr_bit(fcsr_cc));
       break;
     case C_ULE_D:
       set_fcsr_bit(fcsr_cc, (fs <= ft) || (std::isnan(fs) || std::isnan(ft)));
+      TraceRegWr(test_fcsr_bit(fcsr_cc));
       break;
     case CVT_W_D: {  // Convert double to word.
       double rounded;
       int32_t result;
       round_according_to_fcsr(fs, rounded, result, fs);
       set_fpu_register_word(fd_reg(), result);
       if (set_fcsr_round_error(fs, rounded)) {
         set_fpu_register_word_invalid_result(fs, rounded);
       }
+      TraceRegWr(get_fpu_register_word(fd_reg()));
     } break;
     case ROUND_W_D:  // Round double to word (round half to even).
     {
       double rounded = std::floor(fs + 0.5);
       int32_t result = static_cast<int32_t>(rounded);
       if ((result & 1) != 0 && result - fs == 0.5) {
         // If the number is halfway between two integers,
         // round to the even one.
         result--;
       }
       set_fpu_register_word(fd_reg(), result);
       if (set_fcsr_round_error(fs, rounded)) {
         set_fpu_register_word_invalid_result(fs, rounded);
       }
+      TraceRegWr(get_fpu_register_word(fd_reg()));
     } break;
     case TRUNC_W_D:  // Truncate double to word (round towards 0).
     {
       double rounded = trunc(fs);
       int32_t result = static_cast<int32_t>(rounded);
       set_fpu_register_word(fd_reg(), result);
       if (set_fcsr_round_error(fs, rounded)) {
         set_fpu_register_word_invalid_result(fs, rounded);
       }
+      TraceRegWr(get_fpu_register_word(fd_reg()));
     } break;
     case FLOOR_W_D:  // Round double to word towards negative infinity.
     {
       double rounded = std::floor(fs);
       int32_t result = static_cast<int32_t>(rounded);
       set_fpu_register_word(fd_reg(), result);
       if (set_fcsr_round_error(fs, rounded)) {
         set_fpu_register_word_invalid_result(fs, rounded);
       }
+      TraceRegWr(get_fpu_register_word(fd_reg()));
     } break;
     case CEIL_W_D:  // Round double to word towards positive infinity.
     {
       double rounded = std::ceil(fs);
       int32_t result = static_cast<int32_t>(rounded);
       set_fpu_register_word(fd_reg(), result);
       if (set_fcsr_round_error(fs, rounded)) {
         set_fpu_register_word_invalid_result(fs, rounded);
       }
+      TraceRegWr(get_fpu_register_word(fd_reg()));
     } break;
     case CVT_S_D:  // Convert double to float (single).
       set_fpu_register_float(fd_reg(), static_cast<float>(fs));
+      TraceRegWr(get_fpu_register_word(fd_reg()), FLOAT);
       break;
     case CVT_L_D: {  // Mips32r2: Truncate double to 64-bit long-word.
       if (IsFp64Mode()) {
         int64_t result;
         double rounded;
         round64_according_to_fcsr(fs, rounded, result, fs);
         set_fpu_register(fd_reg(), result);
         if (set_fcsr_round64_error(fs, rounded)) {
           set_fpu_register_invalid_result64(fs, rounded);
         }
+        TraceRegWr(get_fpu_register(fd_reg()));
       } else {
         UNSUPPORTED();
       }
       break;
       break;
     }
     case TRUNC_L_D: {  // Mips32r2 instruction.
       DCHECK(IsMipsArchVariant(kMips32r2) || IsMipsArchVariant(kMips32r6));
       double rounded = trunc(fs);
       i64 = static_cast<int64_t>(rounded);
       if (IsFp64Mode()) {
         set_fpu_register(fd_reg(), i64);
         if (set_fcsr_round64_error(fs, rounded)) {
           set_fpu_register_invalid_result64(fs, rounded);
         }
+        TraceRegWr(get_fpu_register(fd_reg()));
       } else {
         UNSUPPORTED();
       }
       break;
     }
     case ROUND_L_D: {  // Mips32r2 instruction.
       DCHECK(IsMipsArchVariant(kMips32r2) || IsMipsArchVariant(kMips32r6));
       double rounded = std::floor(fs + 0.5);
       int64_t result = static_cast<int64_t>(rounded);
       if ((result & 1) != 0 && result - fs == 0.5) {
         // If the number is halfway between two integers,
         // round to the even one.
         result--;
       }
       int64_t i64 = static_cast<int64_t>(result);
       if (IsFp64Mode()) {
         set_fpu_register(fd_reg(), i64);
         if (set_fcsr_round64_error(fs, rounded)) {
           set_fpu_register_invalid_result64(fs, rounded);
         }
+        TraceRegWr(get_fpu_register(fd_reg()));
       } else {
         UNSUPPORTED();
       }
       break;
     }
     case FLOOR_L_D: {  // Mips32r2 instruction.
       DCHECK(IsMipsArchVariant(kMips32r2) || IsMipsArchVariant(kMips32r6));
       double rounded = std::floor(fs);
       int64_t i64 = static_cast<int64_t>(rounded);
       if (IsFp64Mode()) {
         set_fpu_register(fd_reg(), i64);
         if (set_fcsr_round64_error(fs, rounded)) {
           set_fpu_register_invalid_result64(fs, rounded);
         }
+        TraceRegWr(get_fpu_register(fd_reg()));
       } else {
         UNSUPPORTED();
       }
       break;
     }
     case CEIL_L_D: {  // Mips32r2 instruction.
       DCHECK(IsMipsArchVariant(kMips32r2) || IsMipsArchVariant(kMips32r6));
       double rounded = std::ceil(fs);
       int64_t i64 = static_cast<int64_t>(rounded);
       if (IsFp64Mode()) {
         set_fpu_register(fd_reg(), i64);
         if (set_fcsr_round64_error(fs, rounded)) {
           set_fpu_register_invalid_result64(fs, rounded);
         }
+        TraceRegWr(get_fpu_register(fd_reg()));
       } else {
         UNSUPPORTED();
       }
       break;
     }
     case CLASS_D: {  // Mips32r6 instruction
       // Convert double input to uint64_t for easier bit manipulation
       uint64_t classed = bit_cast<uint64_t>(fs);
 
       // Extracting sign, exponent and mantissa from the input double
@@ skipping 47 matching lines @@
 
       // Calculating result according to description of CLASS.D instruction
       result = (posZero << 9) | (posSubnorm << 8) | (posNorm << 7) |
                (posInf << 6) | (negZero << 5) | (negSubnorm << 4) |
                (negNorm << 3) | (negInf << 2) | (quietNan << 1) | signalingNan;
 
       DCHECK(result != 0);
 
       dResult = bit_cast<double>(result);
       set_fpu_register_double(fd_reg(), dResult);
+      TraceRegWr(get_fpu_register(fd_reg()), DOUBLE);
 
       break;
     }
     case C_F_D: {
       set_fcsr_bit(fcsr_cc, false);
+      TraceRegWr(test_fcsr_bit(fcsr_cc));
       break;
     }
     default:
       UNREACHABLE();
   }
 }
 
 
 void Simulator::DecodeTypeRegisterWRsType() {
   float fs = get_fpu_register_float(fs_reg());
   float ft = get_fpu_register_float(ft_reg());
   int32_t alu_out = 0x12345678;
   switch (instr_.FunctionFieldRaw()) {
     case CVT_S_W:  // Convert word to float (single).
       alu_out = get_fpu_register_signed_word(fs_reg());
       set_fpu_register_float(fd_reg(), static_cast<float>(alu_out));
+      TraceRegWr(get_fpu_register_word(fd_reg()), FLOAT);
       break;
     case CVT_D_W:  // Convert word to double.
       alu_out = get_fpu_register_signed_word(fs_reg());
       set_fpu_register_double(fd_reg(), static_cast<double>(alu_out));
+      TraceRegWr(get_fpu_register(fd_reg()), DOUBLE);
       break;
     case CMP_AF:
       set_fpu_register_word(fd_reg(), 0);
+      TraceRegWr(get_fpu_register_word(fd_reg()));
       break;
     case CMP_UN:
       if (std::isnan(fs) || std::isnan(ft)) {
         set_fpu_register_word(fd_reg(), -1);
       } else {
         set_fpu_register_word(fd_reg(), 0);
       }
+      TraceRegWr(get_fpu_register_word(fd_reg()));
       break;
     case CMP_EQ:
       if (fs == ft) {
         set_fpu_register_word(fd_reg(), -1);
       } else {
         set_fpu_register_word(fd_reg(), 0);
       }
+      TraceRegWr(get_fpu_register_word(fd_reg()));
       break;
     case CMP_UEQ:
       if ((fs == ft) || (std::isnan(fs) || std::isnan(ft))) {
         set_fpu_register_word(fd_reg(), -1);
       } else {
         set_fpu_register_word(fd_reg(), 0);
       }
+      TraceRegWr(get_fpu_register_word(fd_reg()));
       break;
     case CMP_LT:
       if (fs < ft) {
         set_fpu_register_word(fd_reg(), -1);
       } else {
         set_fpu_register_word(fd_reg(), 0);
       }
+      TraceRegWr(get_fpu_register_word(fd_reg()));
       break;
     case CMP_ULT:
       if ((fs < ft) || (std::isnan(fs) || std::isnan(ft))) {
         set_fpu_register_word(fd_reg(), -1);
       } else {
         set_fpu_register_word(fd_reg(), 0);
       }
+      TraceRegWr(get_fpu_register_word(fd_reg()));
       break;
     case CMP_LE:
       if (fs <= ft) {
         set_fpu_register_word(fd_reg(), -1);
       } else {
         set_fpu_register_word(fd_reg(), 0);
       }
+      TraceRegWr(get_fpu_register_word(fd_reg()));
       break;
     case CMP_ULE:
       if ((fs <= ft) || (std::isnan(fs) || std::isnan(ft))) {
         set_fpu_register_word(fd_reg(), -1);
       } else {
         set_fpu_register_word(fd_reg(), 0);
       }
+      TraceRegWr(get_fpu_register_word(fd_reg()));
       break;
     case CMP_OR:
       if (!std::isnan(fs) && !std::isnan(ft)) {
         set_fpu_register_word(fd_reg(), -1);
       } else {
         set_fpu_register_word(fd_reg(), 0);
       }
+      TraceRegWr(get_fpu_register_word(fd_reg()));
       break;
     case CMP_UNE:
       if ((fs != ft) || (std::isnan(fs) || std::isnan(ft))) {
         set_fpu_register_word(fd_reg(), -1);
       } else {
         set_fpu_register_word(fd_reg(), 0);
       }
+      TraceRegWr(get_fpu_register_word(fd_reg()));
       break;
     case CMP_NE:
       if (fs != ft) {
         set_fpu_register_word(fd_reg(), -1);
       } else {
         set_fpu_register_word(fd_reg(), 0);
       }
+      TraceRegWr(get_fpu_register_word(fd_reg()));
       break;
     default:
       UNREACHABLE();
   }
 }
 
 
 void Simulator::DecodeTypeRegisterSRsType() {
   float fs, ft, fd;
   fs = get_fpu_register_float(fs_reg());
@@ skipping 34 matching lines @@
           result = upper;
           break;
         case kRoundToMinusInf:
           result = lower;
           break;
       }
       set_fpu_register_float(fd_reg(), result);
       if (result != fs) {
         set_fcsr_bit(kFCSRInexactFlagBit, true);
       }
+      TraceRegWr(get_fpu_register_word(fd_reg()), FLOAT);
       break;
     }
     case ADD_S:
       set_fpu_register_float(
           fd_reg(),
           FPUCanonalizeOperation([](float lhs, float rhs) { return lhs + rhs; },
                                  fs, ft));
+      TraceRegWr(get_fpu_register_word(fd_reg()), FLOAT);
       break;
     case SUB_S:
       set_fpu_register_float(
           fd_reg(),
           FPUCanonalizeOperation([](float lhs, float rhs) { return lhs - rhs; },
                                  fs, ft));
+      TraceRegWr(get_fpu_register_word(fd_reg()), FLOAT);
       break;
     case MADDF_S:
       DCHECK(IsMipsArchVariant(kMips32r6));
       set_fpu_register_float(fd_reg(), std::fma(fs, ft, fd));
+      TraceRegWr(get_fpu_register_word(fd_reg()), FLOAT);
       break;
     case MSUBF_S:
       DCHECK(IsMipsArchVariant(kMips32r6));
       set_fpu_register_float(fd_reg(), std::fma(-fs, ft, fd));
+      TraceRegWr(get_fpu_register_word(fd_reg()), FLOAT);
       break;
     case MUL_S:
       set_fpu_register_float(
           fd_reg(),
           FPUCanonalizeOperation([](float lhs, float rhs) { return lhs * rhs; },
                                  fs, ft));
+      TraceRegWr(get_fpu_register_word(fd_reg()), FLOAT);
       break;
     case DIV_S:
       set_fpu_register_float(
           fd_reg(),
           FPUCanonalizeOperation([](float lhs, float rhs) { return lhs / rhs; },
                                  fs, ft));
+      TraceRegWr(get_fpu_register_word(fd_reg()), FLOAT);
       break;
     case ABS_S:
       set_fpu_register_float(
           fd_reg(),
           FPUCanonalizeOperation([](float fs) { return FPAbs(fs); }, fs));
+      TraceRegWr(get_fpu_register_word(fd_reg()), FLOAT);
       break;
     case MOV_S:
       set_fpu_register_float(fd_reg(), fs);
+      TraceRegWr(get_fpu_register_word(fd_reg()), FLOAT);
       break;
     case NEG_S:
       set_fpu_register_float(
           fd_reg(), FPUCanonalizeOperation([](float src) { return -src; },
                                            KeepSign::yes, fs));
+      TraceRegWr(get_fpu_register_word(fd_reg()), FLOAT);
       break;
     case SQRT_S:
       set_fpu_register_float(
           fd_reg(),
           FPUCanonalizeOperation([](float src) { return std::sqrt(src); }, fs));
+      TraceRegWr(get_fpu_register_word(fd_reg()), FLOAT);
       break;
     case RSQRT_S:
       set_fpu_register_float(
           fd_reg(), FPUCanonalizeOperation(
                         [](float src) { return 1.0 / std::sqrt(src); }, fs));
+      TraceRegWr(get_fpu_register_word(fd_reg()), FLOAT);
       break;
     case RECIP_S:
       set_fpu_register_float(
           fd_reg(),
           FPUCanonalizeOperation([](float src) { return 1.0 / src; }, fs));
+      TraceRegWr(get_fpu_register_word(fd_reg()), FLOAT);
       break;
     case C_F_D:
       set_fcsr_bit(fcsr_cc, false);
+      TraceRegWr(test_fcsr_bit(fcsr_cc));
       break;
     case C_UN_D:
       set_fcsr_bit(fcsr_cc, std::isnan(fs) || std::isnan(ft));
+      TraceRegWr(test_fcsr_bit(fcsr_cc));
       break;
     case C_EQ_D:
       set_fcsr_bit(fcsr_cc, (fs == ft));
+      TraceRegWr(test_fcsr_bit(fcsr_cc));
       break;
     case C_UEQ_D:
       set_fcsr_bit(fcsr_cc, (fs == ft) || (std::isnan(fs) || std::isnan(ft)));
+      TraceRegWr(test_fcsr_bit(fcsr_cc));
       break;
     case C_OLT_D:
       set_fcsr_bit(fcsr_cc, (fs < ft));
+      TraceRegWr(test_fcsr_bit(fcsr_cc));
       break;
     case C_ULT_D:
       set_fcsr_bit(fcsr_cc, (fs < ft) || (std::isnan(fs) || std::isnan(ft)));
+      TraceRegWr(test_fcsr_bit(fcsr_cc));
       break;
     case C_OLE_D:
       set_fcsr_bit(fcsr_cc, (fs <= ft));
+      TraceRegWr(test_fcsr_bit(fcsr_cc));
       break;
     case C_ULE_D:
       set_fcsr_bit(fcsr_cc, (fs <= ft) || (std::isnan(fs) || std::isnan(ft)));
+      TraceRegWr(test_fcsr_bit(fcsr_cc));
       break;
     case CVT_D_S:
       set_fpu_register_double(fd_reg(), static_cast<double>(fs));
+      TraceRegWr(get_fpu_register(fd_reg()), DOUBLE);
       break;
     case SEL:
       DCHECK(IsMipsArchVariant(kMips32r6));
       set_fpu_register_float(fd_reg(), (fd_int & 0x1) == 0 ? fs : ft);
+      TraceRegWr(get_fpu_register_word(fd_reg()), FLOAT);
       break;
     case CLASS_S: {  // Mips32r6 instruction
       // Convert float input to uint32_t for easier bit manipulation
       float fs = get_fpu_register_float(fs_reg());
       uint32_t classed = bit_cast<uint32_t>(fs);
 
       // Extracting sign, exponent and mantissa from the input float
       uint32_t sign = (classed >> 31) & 1;
       uint32_t exponent = (classed >> 23) & 0x000000ff;
       uint32_t mantissa = classed & 0x007fffff;
@@ skipping 44 matching lines @@
 
       // Calculating result according to description of CLASS.S instruction
       result = (posZero << 9) | (posSubnorm << 8) | (posNorm << 7) |
                (posInf << 6) | (negZero << 5) | (negSubnorm << 4) |
                (negNorm << 3) | (negInf << 2) | (quietNan << 1) | signalingNan;
 
       DCHECK(result != 0);
 
       fResult = bit_cast<float>(result);
       set_fpu_register_float(fd_reg(), fResult);
+      TraceRegWr(get_fpu_register_word(fd_reg()), FLOAT);
 
       break;
     }
     case SELEQZ_C:
       DCHECK(IsMipsArchVariant(kMips32r6));
       set_fpu_register_float(fd_reg(), (ft_int & 0x1) == 0
                                            ? get_fpu_register_float(fs_reg())
                                            : 0.0);
+      TraceRegWr(get_fpu_register_word(fd_reg()), FLOAT);
       break;
     case SELNEZ_C:
       DCHECK(IsMipsArchVariant(kMips32r6));
       set_fpu_register_float(fd_reg(), (ft_int & 0x1) != 0
                                            ? get_fpu_register_float(fs_reg())
                                            : 0.0);
+      TraceRegWr(get_fpu_register_word(fd_reg()), FLOAT);
       break;
     case MOVZ_C: {
       DCHECK(IsMipsArchVariant(kMips32r2));
       if (rt() == 0) {
         set_fpu_register_float(fd_reg(), fs);
       }
+      TraceRegWr(get_fpu_register_word(fd_reg()), FLOAT);
       break;
     }
     case MOVN_C: {
       DCHECK(IsMipsArchVariant(kMips32r2));
       if (rt() != 0) {
         set_fpu_register_float(fd_reg(), fs);
       }
+      TraceRegWr(get_fpu_register_word(fd_reg()), FLOAT);
       break;
     }
     case MOVF: {
       // Same function field for MOVT.D and MOVF.D
       uint32_t ft_cc = (ft_reg() >> 2) & 0x7;
       ft_cc = get_fcsr_condition_bit(ft_cc);
 
       if (instr_.Bit(16)) {  // Read Tf bit.
         // MOVT.D
         if (test_fcsr_bit(ft_cc)) set_fpu_register_float(fd_reg(), fs);
       } else {
         // MOVF.D
         if (!test_fcsr_bit(ft_cc)) set_fpu_register_float(fd_reg(), fs);
       }
+      TraceRegWr(get_fpu_register_word(fd_reg()), FLOAT);
       break;
     }
     case TRUNC_W_S: {  // Truncate single to word (round towards 0).
       float rounded = trunc(fs);
       int32_t result = static_cast<int32_t>(rounded);
       set_fpu_register_word(fd_reg(), result);
       if (set_fcsr_round_error(fs, rounded)) {
         set_fpu_register_word_invalid_result(fs, rounded);
       }
+      TraceRegWr(get_fpu_register_word(fd_reg()));
     } break;
     case TRUNC_L_S: {  // Mips32r2 instruction.
       DCHECK(IsMipsArchVariant(kMips32r2) || IsMipsArchVariant(kMips32r6));
       float rounded = trunc(fs);
       int64_t i64 = static_cast<int64_t>(rounded);
       if (IsFp64Mode()) {
         set_fpu_register(fd_reg(), i64);
         if (set_fcsr_round64_error(fs, rounded)) {
           set_fpu_register_invalid_result64(fs, rounded);
         }
+        TraceRegWr(get_fpu_register(fd_reg()));
       } else {
         UNSUPPORTED();
       }
       break;
     }
     case FLOOR_W_S:  // Round double to word towards negative infinity.
     {
       float rounded = std::floor(fs);
       int32_t result = static_cast<int32_t>(rounded);
       set_fpu_register_word(fd_reg(), result);
       if (set_fcsr_round_error(fs, rounded)) {
         set_fpu_register_word_invalid_result(fs, rounded);
       }
+      TraceRegWr(get_fpu_register_word(fd_reg()));
     } break;
     case FLOOR_L_S: {  // Mips32r2 instruction.
       DCHECK(IsMipsArchVariant(kMips32r2) || IsMipsArchVariant(kMips32r6));
       float rounded = std::floor(fs);
       int64_t i64 = static_cast<int64_t>(rounded);
       if (IsFp64Mode()) {
         set_fpu_register(fd_reg(), i64);
         if (set_fcsr_round64_error(fs, rounded)) {
           set_fpu_register_invalid_result64(fs, rounded);
         }
+        TraceRegWr(get_fpu_register(fd_reg()));
       } else {
         UNSUPPORTED();
       }
       break;
     }
     case ROUND_W_S: {
       float rounded = std::floor(fs + 0.5);
       int32_t result = static_cast<int32_t>(rounded);
       if ((result & 1) != 0 && result - fs == 0.5) {
         // If the number is halfway between two integers,
         // round to the even one.
         result--;
       }
       set_fpu_register_word(fd_reg(), result);
       if (set_fcsr_round_error(fs, rounded)) {
         set_fpu_register_word_invalid_result(fs, rounded);
       }
+      TraceRegWr(get_fpu_register_word(fd_reg()));
       break;
     }
     case ROUND_L_S: {  // Mips32r2 instruction.
       DCHECK(IsMipsArchVariant(kMips32r2) || IsMipsArchVariant(kMips32r6));
       float rounded = std::floor(fs + 0.5);
       int64_t result = static_cast<int64_t>(rounded);
       if ((result & 1) != 0 && result - fs == 0.5) {
         // If the number is halfway between two integers,
         // round to the even one.
         result--;
       }
       int64_t i64 = static_cast<int64_t>(result);
       if (IsFp64Mode()) {
         set_fpu_register(fd_reg(), i64);
         if (set_fcsr_round64_error(fs, rounded)) {
           set_fpu_register_invalid_result64(fs, rounded);
         }
+        TraceRegWr(get_fpu_register(fd_reg()));
       } else {
         UNSUPPORTED();
       }
       break;
     }
     case CEIL_W_S:  // Round double to word towards positive infinity.
     {
       float rounded = std::ceil(fs);
       int32_t result = static_cast<int32_t>(rounded);
       set_fpu_register_word(fd_reg(), result);
       if (set_fcsr_round_error(fs, rounded)) {
         set_fpu_register_word_invalid_result(fs, rounded);
       }
+      TraceRegWr(get_fpu_register_word(fd_reg()));
     } break;
     case CEIL_L_S: {  // Mips32r2 instruction.
       DCHECK(IsMipsArchVariant(kMips32r2) || IsMipsArchVariant(kMips32r6));
       float rounded = std::ceil(fs);
       int64_t i64 = static_cast<int64_t>(rounded);
       if (IsFp64Mode()) {
         set_fpu_register(fd_reg(), i64);
         if (set_fcsr_round64_error(fs, rounded)) {
           set_fpu_register_invalid_result64(fs, rounded);
         }
+        TraceRegWr(get_fpu_register(fd_reg()));
       } else {
         UNSUPPORTED();
       }
       break;
     }
     case MIN:
       DCHECK(IsMipsArchVariant(kMips32r6));
       set_fpu_register_float(fd_reg(), FPUMin(ft, fs));
+      TraceRegWr(get_fpu_register_word(fd_reg()), FLOAT);
       break;
     case MAX:
       DCHECK(IsMipsArchVariant(kMips32r6));
       set_fpu_register_float(fd_reg(), FPUMax(ft, fs));
+      TraceRegWr(get_fpu_register_word(fd_reg()), FLOAT);
       break;
     case MINA:
       DCHECK(IsMipsArchVariant(kMips32r6));
       set_fpu_register_float(fd_reg(), FPUMinA(ft, fs));
+      TraceRegWr(get_fpu_register_word(fd_reg()), FLOAT);
       break;
     case MAXA:
       DCHECK(IsMipsArchVariant(kMips32r6));
       set_fpu_register_float(fd_reg(), FPUMaxA(ft, fs));
+      TraceRegWr(get_fpu_register_word(fd_reg()), FLOAT);
       break;
     case CVT_L_S: {
       if (IsFp64Mode()) {
         int64_t result;
         float rounded;
         round64_according_to_fcsr(fs, rounded, result, fs);
         set_fpu_register(fd_reg(), result);
         if (set_fcsr_round64_error(fs, rounded)) {
           set_fpu_register_invalid_result64(fs, rounded);
         }
+        TraceRegWr(get_fpu_register(fd_reg()));
       } else {
         UNSUPPORTED();
       }
       break;
     }
     case CVT_W_S: {
       float rounded;
       int32_t result;
       round_according_to_fcsr(fs, rounded, result, fs);
       set_fpu_register_word(fd_reg(), result);
       if (set_fcsr_round_error(fs, rounded)) {
         set_fpu_register_word_invalid_result(fs, rounded);
       }
+      TraceRegWr(get_fpu_register_word(fd_reg()));
       break;
     }
     default:
       // CVT_W_S CVT_L_S  ROUND_W_S ROUND_L_S FLOOR_W_S FLOOR_L_S
       // CEIL_W_S CEIL_L_S CVT_PS_S are unimplemented.
       UNREACHABLE();
   }
 }
 
 
 void Simulator::DecodeTypeRegisterLRsType() {
   double fs = get_fpu_register_double(fs_reg());
   double ft = get_fpu_register_double(ft_reg());
   switch (instr_.FunctionFieldRaw()) {
     case CVT_D_L:  // Mips32r2 instruction.
       // Watch the signs here, we want 2 32-bit vals
       // to make a sign-64.
       int64_t i64;
       if (IsFp64Mode()) {
         i64 = get_fpu_register(fs_reg());
       } else {
         i64 = static_cast<uint32_t>(get_fpu_register_word(fs_reg()));
         i64 |= static_cast<int64_t>(get_fpu_register_word(fs_reg() + 1)) << 32;
       }
       set_fpu_register_double(fd_reg(), static_cast<double>(i64));
+      TraceRegWr(get_fpu_register(fd_reg()), DOUBLE);
       break;
     case CVT_S_L:
       if (IsFp64Mode()) {
         i64 = get_fpu_register(fs_reg());
       } else {
         i64 = static_cast<uint32_t>(get_fpu_register_word(fs_reg()));
         i64 |= static_cast<int64_t>(get_fpu_register_word(fs_reg() + 1)) << 32;
       }
       set_fpu_register_float(fd_reg(), static_cast<float>(i64));
+      TraceRegWr(get_fpu_register_word(fd_reg()), FLOAT);
       break;
     case CMP_AF:  // Mips64r6 CMP.D instructions.
       set_fpu_register(fd_reg(), 0);
+      TraceRegWr(get_fpu_register(fd_reg()));
       break;
     case CMP_UN:
       if (std::isnan(fs) || std::isnan(ft)) {
         set_fpu_register(fd_reg(), -1);
       } else {
         set_fpu_register(fd_reg(), 0);
       }
+      TraceRegWr(get_fpu_register(fd_reg()));
       break;
     case CMP_EQ:
       if (fs == ft) {
         set_fpu_register(fd_reg(), -1);
       } else {
         set_fpu_register(fd_reg(), 0);
       }
+      TraceRegWr(get_fpu_register(fd_reg()));
       break;
     case CMP_UEQ:
       if ((fs == ft) || (std::isnan(fs) || std::isnan(ft))) {
         set_fpu_register(fd_reg(), -1);
       } else {
         set_fpu_register(fd_reg(), 0);
       }
+      TraceRegWr(get_fpu_register(fd_reg()));
       break;
     case CMP_LT:
       if (fs < ft) {
         set_fpu_register(fd_reg(), -1);
       } else {
         set_fpu_register(fd_reg(), 0);
       }
+      TraceRegWr(get_fpu_register(fd_reg()));
       break;
     case CMP_ULT:
       if ((fs < ft) || (std::isnan(fs) || std::isnan(ft))) {
         set_fpu_register(fd_reg(), -1);
       } else {
         set_fpu_register(fd_reg(), 0);
       }
+      TraceRegWr(get_fpu_register(fd_reg()));
       break;
     case CMP_LE:
       if (fs <= ft) {
         set_fpu_register(fd_reg(), -1);
       } else {
         set_fpu_register(fd_reg(), 0);
       }
+      TraceRegWr(get_fpu_register(fd_reg()));
       break;
     case CMP_ULE:
       if ((fs <= ft) || (std::isnan(fs) || std::isnan(ft))) {
         set_fpu_register(fd_reg(), -1);
       } else {
         set_fpu_register(fd_reg(), 0);
       }
+      TraceRegWr(get_fpu_register(fd_reg()));
       break;
     case CMP_OR:
       if (!std::isnan(fs) && !std::isnan(ft)) {
         set_fpu_register(fd_reg(), -1);
       } else {
         set_fpu_register(fd_reg(), 0);
       }
+      TraceRegWr(get_fpu_register(fd_reg()));
       break;
     case CMP_UNE:
       if ((fs != ft) || (std::isnan(fs) || std::isnan(ft))) {
         set_fpu_register(fd_reg(), -1);
       } else {
         set_fpu_register(fd_reg(), 0);
       }
+      TraceRegWr(get_fpu_register(fd_reg()));
       break;
     case CMP_NE:
       if (fs != ft && (!std::isnan(fs) && !std::isnan(ft))) {
         set_fpu_register(fd_reg(), -1);
       } else {
         set_fpu_register(fd_reg(), 0);
       }
+      TraceRegWr(get_fpu_register(fd_reg()));
       break;
     default:
       UNREACHABLE();
   }
 }
 
 
 void Simulator::DecodeTypeRegisterCOP1() {
   switch (instr_.RsFieldRaw()) {
     case CFC1:
       // At the moment only FCSR is supported.
       DCHECK(fs_reg() == kFCSRRegister);
       set_register(rt_reg(), FCSR_);
+      TraceRegWr(get_register(rt_reg()));
       break;
     case MFC1:
       set_register(rt_reg(), get_fpu_register_word(fs_reg()));
+      TraceRegWr(get_register(rt_reg()));
       break;
     case MFHC1:
       if (IsFp64Mode()) {
         set_register(rt_reg(), get_fpu_register_hi_word(fs_reg()));
       } else {
         set_register(rt_reg(), get_fpu_register_word(fs_reg() + 1));
       }
+      TraceRegWr(get_register(rt_reg()));
       break;
     case CTC1: {
       // At the moment only FCSR is supported.
       DCHECK(fs_reg() == kFCSRRegister);
       int32_t reg = registers_[rt_reg()];
       if (IsMipsArchVariant(kMips32r6)) {
         FCSR_ = reg | kFCSRNaN2008FlagMask;
       } else {
         DCHECK(IsMipsArchVariant(kMips32r1) || IsMipsArchVariant(kMips32r2));
         FCSR_ = reg & ~kFCSRNaN2008FlagMask;
       }
+      TraceRegWr(static_cast<int32_t>(FCSR_), FLOAT);
       break;
     }
     case MTC1:
       // Hardware writes upper 32-bits to zero on mtc1.
       set_fpu_register_hi_word(fs_reg(), 0);
       set_fpu_register_word(fs_reg(), registers_[rt_reg()]);
+      TraceRegWr(get_fpu_register_word(fs_reg()), FLOAT);
       break;
     case MTHC1:
       if (IsFp64Mode()) {
         set_fpu_register_hi_word(fs_reg(), registers_[rt_reg()]);
+        TraceRegWr(get_fpu_register(fs_reg()), DOUBLE);
       } else {
         set_fpu_register_word(fs_reg() + 1, registers_[rt_reg()]);
+        if (fs_reg() % 2) {
+          TraceRegWr(get_fpu_register_word(fs_reg() + 1), FLOAT);
+        } else {
+          TraceRegWr(get_fpu_register(fs_reg()), DOUBLE);
+        }
       }
       break;
     case S: {
       DecodeTypeRegisterSRsType();
       break;
     }
     case D:
       DecodeTypeRegisterDRsType();
       break;
     case W:
@@ skipping 13 matching lines @@
 
 void Simulator::DecodeTypeRegisterCOP1X() {
   switch (instr_.FunctionFieldRaw()) {
     case MADD_S: {
       DCHECK(IsMipsArchVariant(kMips32r2));
       float fr, ft, fs;
       fr = get_fpu_register_float(fr_reg());
       fs = get_fpu_register_float(fs_reg());
       ft = get_fpu_register_float(ft_reg());
       set_fpu_register_float(fd_reg(), fs * ft + fr);
+      TraceRegWr(get_fpu_register_word(fd_reg()), FLOAT);
       break;
     }
     case MSUB_S: {
       DCHECK(IsMipsArchVariant(kMips32r2));
       float fr, ft, fs;
       fr = get_fpu_register_float(fr_reg());
       fs = get_fpu_register_float(fs_reg());
       ft = get_fpu_register_float(ft_reg());
       set_fpu_register_float(fd_reg(), fs * ft - fr);
+      TraceRegWr(get_fpu_register_word(fd_reg()), FLOAT);
       break;
     }
     case MADD_D: {
       DCHECK(IsMipsArchVariant(kMips32r2));
       double fr, ft, fs;
       fr = get_fpu_register_double(fr_reg());
       fs = get_fpu_register_double(fs_reg());
       ft = get_fpu_register_double(ft_reg());
       set_fpu_register_double(fd_reg(), fs * ft + fr);
+      TraceRegWr(get_fpu_register(fd_reg()), DOUBLE);
       break;
     }
     case MSUB_D: {
       DCHECK(IsMipsArchVariant(kMips32r2));
       double fr, ft, fs;
       fr = get_fpu_register_double(fr_reg());
       fs = get_fpu_register_double(fs_reg());
       ft = get_fpu_register_double(ft_reg());
       set_fpu_register_double(fd_reg(), fs * ft - fr);
+      TraceRegWr(get_fpu_register(fd_reg()), DOUBLE);
       break;
     }
     default:
       UNREACHABLE();
   }
 }
 
 
 void Simulator::DecodeTypeRegisterSPECIAL() {
   int64_t alu_out = 0x12345678;
@@ skipping 852 matching lines @@
       uint8_t al_offset = (rs + se_imm16) & kPointerAlignmentMask;
       uint32_t mask = (1 << al_offset * 8) - 1;
       addr = rs + se_imm16 - al_offset;
       uint32_t mem_value = ReadW(addr, instr_.instr());
       mem_value = (rt << al_offset * 8) | (mem_value & mask);
       WriteW(addr, mem_value, instr_.instr());
       break;
     }
     case LWC1:
       set_fpu_register_hi_word(ft_reg, 0);
-      set_fpu_register_word(ft_reg, ReadW(rs + se_imm16, instr_.instr()));
+      set_fpu_register_word(ft_reg,
+                            ReadW(rs + se_imm16, instr_.instr(), FLOAT));
+      if (ft_reg % 2) {
+        TraceMemRd(rs + se_imm16, get_fpu_register(ft_reg - 1), FLOAT_DOUBLE);
+      } else {
+        TraceMemRd(rs + se_imm16, get_fpu_register_word(ft_reg), FLOAT);
+      }
       break;
     case LDC1:
       set_fpu_register_double(ft_reg, ReadD(rs + se_imm16, instr_.instr()));
+      TraceMemRd(rs + se_imm16, get_fpu_register(ft_reg), DOUBLE);
       break;
     case SWC1:
       WriteW(rs + se_imm16, get_fpu_register_word(ft_reg), instr_.instr());
+      TraceMemWr(rs + se_imm16, get_fpu_register_word(ft_reg));
       break;
     case SDC1:
       WriteD(rs + se_imm16, get_fpu_register_double(ft_reg), instr_.instr());
+      TraceMemWr(rs + se_imm16, get_fpu_register(ft_reg));
       break;
     // ------------- PC-Relative instructions.
     case PCREL: {
       // rt field: checking 5-bits.
       int32_t imm21 = instr_.Imm21Value();
       int32_t current_pc = get_pc();
       uint8_t rt = (imm21 >> kImm16Bits);
       switch (rt) {
         case ALUIPC:
           addr = current_pc + (se_imm16 << 16);
@@ skipping 299 matching lines @@
 
 
 #undef UNSUPPORTED
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // USE_SIMULATOR
 
 #endif  // V8_TARGET_ARCH_MIPS