[turbofan] Support for %_DoubleHi, %_DoubleLo and %_ConstructDouble.

src/compiler/machine-operator-reducer.cc

Index: src/compiler/machine-operator-reducer.cc
diff --git a/src/compiler/machine-operator-reducer.cc b/src/compiler/machine-operator-reducer.cc
index 5630bc8ef0ffae22a16159996867e751e3ab3884..4be8c6e0369d49b50cc6545f63479154fcaa5692 100644
--- a/src/compiler/machine-operator-reducer.cc
+++ b/src/compiler/machine-operator-reducer.cc
@@ -433,6 +433,8 @@ Reduction MachineOperatorReducer::Reduce(Node* node) {
       if (m.IsChangeFloat32ToFloat64()) return Replace(m.node()->InputAt(0));
       break;
     }
+    case IrOpcode::kFloat64InsertWord32:
+      return ReduceFloat64InsertWord32(node);
     case IrOpcode::kStore:
       return ReduceStore(node);
     default:
@@ -975,6 +977,19 @@ Reduction MachineOperatorReducer::ReduceWord32Or(Node* node) {
 }
 
 
+Reduction MachineOperatorReducer::ReduceFloat64InsertWord32(Node* node) {
+  DCHECK_EQ(IrOpcode::kFloat64InsertWord32, node->opcode());
+  Float64Matcher mlhs(node->InputAt(0));
+  Uint32Matcher mrhs(node->InputAt(1));
+  if (mlhs.HasValue() && mrhs.HasValue()) {
+    return ReplaceFloat64(bit_cast<double>(
+        base::bits::InsertElement64(bit_cast<uint64_t>(mlhs.Value()),
+                                    mrhs.Value(), OpParameter<int>(node))));
+  }
+  return NoChange();
+}
+
+
 CommonOperatorBuilder* MachineOperatorReducer::common() const {
   return jsgraph()->common();
 }