Implement UnaligedLoad and UnaligedStore turbofan operators.

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 a93713824dc2bf387aefc22f1eaaebffeff1b080..2fa47ef12dfe21cc4e7495c8f4e7175d818dcdf8 100644
--- a/src/compiler/machine-operator-reducer.cc
+++ b/src/compiler/machine-operator-reducer.cc
@@ -568,6 +568,7 @@ Reduction MachineOperatorReducer::Reduce(Node* node) {
     case IrOpcode::kFloat64InsertHighWord32:
       return ReduceFloat64InsertHighWord32(node);
     case IrOpcode::kStore:
+    case IrOpcode::kUnalignedStore:
     case IrOpcode::kCheckedStore:
       return ReduceStore(node);
     case IrOpcode::kFloat64Equal:
@@ -782,9 +783,13 @@ Reduction MachineOperatorReducer::ReduceStore(Node* node) {
   if (nm.IsCheckedStore()) {
     rep = CheckedStoreRepresentationOf(node->op());
     value_input = 3;
-  } else {
+  } else if (nm.IsStore()) {
     rep = StoreRepresentationOf(node->op()).representation();
     value_input = 2;
+  } else {
+    DCHECK(nm.IsUnalignedStore());
+    rep = UnalignedStoreRepresentationOf(node->op());
+    value_input = 2;
   }
 
   Node* const value = node->InputAt(value_input);