Use signaling NaN for holes in fixed double arrays.

src/x64/lithium-codegen-x64.cc

Index: src/x64/lithium-codegen-x64.cc
diff --git a/src/x64/lithium-codegen-x64.cc b/src/x64/lithium-codegen-x64.cc
index ffe1a5291000382daced4ccefc326de2dbe9a8a8..6b644ecc7203d791bcb5b1918c55858692e5a9df 100644
--- a/src/x64/lithium-codegen-x64.cc
+++ b/src/x64/lithium-codegen-x64.cc
@@ -3985,10 +3985,13 @@ void LCodeGen::DoMathLog(LMathLog* instr) {
   __ ucomisd(input_reg, xmm_scratch);
   __ j(above, &positive, Label::kNear);
   __ j(not_carry, &zero, Label::kNear);
-  ExternalReference nan =
-      ExternalReference::address_of_canonical_non_hole_nan();
-  Operand nan_operand = masm()->ExternalOperand(nan);
-  __ movsd(input_reg, nan_operand);
+  if (CpuFeatures::IsSupported(AVX)) {
+    CpuFeatureScope scope2(masm(), AVX);
+    __ vdivsd(input_reg, xmm_scratch, xmm_scratch);
+  } else {
+    __ divsd(xmm_scratch, xmm_scratch);
+    __ movsd(input_reg, xmm_scratch);
+  }
   __ jmp(&done, Label::kNear);
   __ bind(&zero);
   ExternalReference ninf =
@@ -4412,17 +4415,10 @@ void LCodeGen::DoStoreKeyedFixedDoubleArray(LStoreKeyed* instr) {
     __ movsxlq(ToRegister(key), ToRegister(key));
   }
   if (instr->NeedsCanonicalization()) {
-    Label have_value;
-
-    __ ucomisd(value, value);
-    __ j(parity_odd, &have_value, Label::kNear);  // NaN.
-
-    __ Set(kScratchRegister,
-           bit_cast<uint64_t>(
-               FixedDoubleArray::canonical_not_the_hole_nan_as_double()));
-    __ movq(value, kScratchRegister);
-
-    __ bind(&have_value);
+    XMMRegister xmm_scratch = double_scratch0();
+    // Turn potential sNaN value into qNaN.
+    __ xorps(xmm_scratch, xmm_scratch);
+    __ subsd(value, xmm_scratch);
   }
 
   Operand double_store_operand = BuildFastArrayOperand(