[turbofan] Prevent storing signalling NaNs into holey double arrays.

src/compiler/mips/code-generator-mips.cc

Index: src/compiler/mips/code-generator-mips.cc
diff --git a/src/compiler/mips/code-generator-mips.cc b/src/compiler/mips/code-generator-mips.cc
index 83b7081c8dbe63f487e3160b22f9f7dd850a95d7..d1c5b328905476f064a11a18fcfef3df7bb31ec7 100644
--- a/src/compiler/mips/code-generator-mips.cc
+++ b/src/compiler/mips/code-generator-mips.cc
@@ -1276,6 +1276,20 @@ CodeGenerator::CodeGenResult CodeGenerator::AssembleArchInstruction(
     case kMipsFloat64InsertHighWord32:
       __ FmoveHigh(i.OutputDoubleRegister(), i.InputRegister(1));
       break;
+    case kMipsFloat64SilenceNaN: {
+      FPURegister value = i.InputDoubleRegister(0);
+      FPURegister result = i.OutputDoubleRegister();
+      Register scratch0 = i.TempRegister(0);
+      Label is_nan, not_nan;
+      __ BranchF(NULL, &is_nan, eq, value, value);
+      __ Branch(&not_nan);
+      __ bind(&is_nan);
+      __ LoadRoot(scratch0, Heap::kNanValueRootIndex);
+      __ ldc1(result, FieldMemOperand(scratch0, HeapNumber::kValueOffset));
+      __ bind(&not_nan);
+      break;
+    }
+
     // ... more basic instructions ...
 
     case kMipsLbu: