A64: Fix a few simulation inaccuracies.

src/a64/utils-a64.h

Index: src/a64/utils-a64.h
diff --git a/src/a64/utils-a64.h b/src/a64/utils-a64.h
index 16c51a9c8b52770b44d09fe738adc1cc34dbd80c..c14ea95f97b757c146b809d45ae5152357fbfb59 100644
--- a/src/a64/utils-a64.h
+++ b/src/a64/utils-a64.h
@@ -70,7 +70,7 @@ static inline double rawbits_to_double(uint64_t bits) {
 }
 
 
-// Bits counting.
+// Bit counting.
 int CountLeadingZeros(uint64_t value, int width);
 int CountLeadingSignBits(int64_t value, int width);
 int CountTrailingZeros(uint64_t value, int width);
@@ -80,9 +80,8 @@ int MaskToBit(uint64_t mask);
 
 // NaN tests.
 inline bool IsSignallingNaN(double num) {
-  const uint64_t kFP64QuietNaNMask = 0x0008000000000000UL;
   uint64_t raw = double_to_rawbits(num);
-  if (std::isnan(num) && ((raw & kFP64QuietNaNMask) == 0)) {
+  if (std::isnan(num) && ((raw & kDQuietNanMask) == 0)) {
     return true;
   }
   return false;
@@ -90,9 +89,8 @@ inline bool IsSignallingNaN(double num) {
 
 
 inline bool IsSignallingNaN(float num) {
-  const uint64_t kFP32QuietNaNMask = 0x00400000UL;
   uint32_t raw = float_to_rawbits(num);
-  if (std::isnan(num) && ((raw & kFP32QuietNaNMask) == 0)) {
+  if (std::isnan(num) && ((raw & kSQuietNanMask) == 0)) {
     return true;
   }
   return false;
@@ -104,6 +102,30 @@ inline bool IsQuietNaN(T num) {
   return std::isnan(num) && !IsSignallingNaN(num);
 }
 
+
+// Convert the NaN in 'num' to a quiet NaN.
+inline double ToQuietNaN(double num) {
+  ASSERT(isnan(num));
+  return rawbits_to_double(double_to_rawbits(num) | kDQuietNanMask);
+}
+
+
+inline float ToQuietNaN(float num) {
+  ASSERT(isnan(num));
+  return rawbits_to_float(float_to_rawbits(num) | kSQuietNanMask);
+}
+
+
+// Fused multiply-add.
+inline double FusedMultiplyAdd(double op1, double op2, double a) {
+  return fma(op1, op2, a);
+}
+
+
+inline float FusedMultiplyAdd(float op1, float op2, float a) {
+  return fmaf(op1, op2, a);
+}
+
 } }  // namespace v8::internal
 
 #endif  // V8_A64_UTILS_A64_H_