[wasm] Change the default lowering of stores.

src/compiler/int64-lowering.cc

Index: src/compiler/int64-lowering.cc
diff --git a/src/compiler/int64-lowering.cc b/src/compiler/int64-lowering.cc
index ff61aa765d244abbc2c34ad569c609cb1e8739f0..ae5672df32f0eb38cc9b58ba9e86216345d7f03e 100644
--- a/src/compiler/int64-lowering.cc
+++ b/src/compiler/int64-lowering.cc
@@ -237,7 +237,7 @@ void Int64Lowering::LowerNode(Node* node) {
         NodeProperties::ChangeOp(node, store_op);
         ReplaceNode(node, node, high_node);
       } else {
-        DefaultLowering(node);
+        DefaultLowering(node, true);
       }
       break;
     }
@@ -826,7 +826,7 @@ void Int64Lowering::LowerComparison(Node* node, const Operator* high_word_op,
   ReplaceNode(node, replacement, nullptr);
 }
 
-bool Int64Lowering::DefaultLowering(Node* node) {
+bool Int64Lowering::DefaultLowering(Node* node, bool low_word_only) {
   bool something_changed = false;
   for (int i = NodeProperties::PastValueIndex(node) - 1; i >= 0; i--) {
     Node* input = node->InputAt(i);
@@ -834,7 +834,7 @@ bool Int64Lowering::DefaultLowering(Node* node) {
       something_changed = true;
       node->ReplaceInput(i, GetReplacementLow(input));
     }
-    if (HasReplacementHigh(input)) {
+    if (!low_word_only && HasReplacementHigh(input)) {
       something_changed = true;
       node->InsertInput(zone(), i + 1, GetReplacementHigh(input));
     }