Use signaling NaN for holes in fixed double arrays.

src/arm64/lithium-codegen-arm64.cc

Index: src/arm64/lithium-codegen-arm64.cc
diff --git a/src/arm64/lithium-codegen-arm64.cc b/src/arm64/lithium-codegen-arm64.cc
index 5a27c4afd535a5198b803bdc5d7eb1b29563804d..2c41989505aecebf796e8913420084e77703ed9b 100644
--- a/src/arm64/lithium-codegen-arm64.cc
+++ b/src/arm64/lithium-codegen-arm64.cc
@@ -3605,12 +3605,9 @@ void LCodeGen::DoLoadKeyedFixedDouble(LLoadKeyedFixedDouble* instr) {
 
   if (instr->hydrogen()->RequiresHoleCheck()) {
     Register scratch = ToRegister(instr->temp());
-    // Detect the hole NaN by adding one to the integer representation of the
-    // result, and checking for overflow.
-    STATIC_ASSERT(kHoleNanInt64 == 0x7fffffffffffffff);
-    __ Ldr(scratch, mem_op);
-    __ Cmn(scratch, 1);
-    DeoptimizeIf(vs, instr, "hole");
+    __ Fmov(scratch, result);
+    __ Eor(scratch, scratch, kHoleNanInt64);
+    DeoptimizeIfZero(scratch, instr, "hole");
   }
 }