[wasm] Change the default lowering of stores.

src/compiler/int64-lowering.cc

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/compiler/int64-lowering.h"
 #include "src/compiler/common-operator.h"
 #include "src/compiler/diamond.h"
 #include "src/compiler/graph.h"
 #include "src/compiler/linkage.h"
 #include "src/compiler/machine-operator.h"
@@ skipping 219 matching lines @@
         } else {
           high_node = graph()->NewNode(store_op, base, index_high,
                                        GetReplacementHigh(value));
         }
 
         node->ReplaceInput(1, index_low);
         node->ReplaceInput(2, GetReplacementLow(value));
         NodeProperties::ChangeOp(node, store_op);
         ReplaceNode(node, node, high_node);
       } else {
-        DefaultLowering(node);
+        DefaultLowering(node, true);
       }
       break;
     }
     case IrOpcode::kStart: {
       int parameter_count = GetParameterCountAfterLowering(signature());
       // Only exchange the node if the parameter count actually changed.
       if (parameter_count != static_cast<int>(signature()->parameter_count())) {
         int delta =
             parameter_count - static_cast<int>(signature()->parameter_count());
         int new_output_count = node->op()->ValueOutputCount() + delta;
@@ skipping 568 matching lines @@
       graph()->NewNode(
           machine()->Word32And(),
           graph()->NewNode(machine()->Word32Equal(), GetReplacementHigh(left),
                            GetReplacementHigh(right)),
           graph()->NewNode(low_word_op, GetReplacementLow(left),
                            GetReplacementLow(right))));
 
   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);
     if (HasReplacementLow(input)) {
       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));
     }
   }
   return something_changed;
 }
 
 void Int64Lowering::ReplaceNode(Node* old, Node* new_low, Node* new_high) {
   // if new_low == nullptr, then also new_high == nullptr.
   DCHECK(new_low != nullptr || new_high == nullptr);
@@ skipping 42 matching lines @@
                     common()->Phi(MachineRepresentation::kWord32, value_count),
                     value_count + 1, inputs_low, false),
                 graph()->NewNode(
                     common()->Phi(MachineRepresentation::kWord32, value_count),
                     value_count + 1, inputs_high, false));
   }
 }
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8