Remove an unneeded temp in instance setters and indexed stores.

runtime/vm/flow_graph_builder.cc

Index: runtime/vm/flow_graph_builder.cc
diff --git a/runtime/vm/flow_graph_builder.cc b/runtime/vm/flow_graph_builder.cc
index 6ca201deeefb4f2d9084d1128758db9eb6d56aa6..2865352efc0385a7c980438e3fc46b8e1e7ba4bf 100644
--- a/runtime/vm/flow_graph_builder.cc
+++ b/runtime/vm/flow_graph_builder.cc
@@ -471,18 +471,13 @@ void EffectGraphVisitor::VisitInstanceGetterNode(InstanceGetterNode* node) {
 
 
 void EffectGraphVisitor::VisitInstanceSetterNode(InstanceSetterNode* node) {
-  // We preallocate a temporary to overlap with the value of the assignment.
-  const Smi& zero = Smi::ZoneHandle(Smi::New(0));
-  AddInstruction(new BindInstr(temp_index(), new ConstantVal(zero)));
-  TempVal* placeholder = new TempVal(temp_index());
-  ArgumentGraphVisitor for_receiver(owner(), temp_index() + 1);
+  ArgumentGraphVisitor for_receiver(owner(), temp_index());
   node->receiver()->Visit(&for_receiver);
   Append(for_receiver);
   ArgumentGraphVisitor for_value(owner(), for_receiver.temp_index());
   node->value()->Visit(&for_value);
   Append(for_value);
   InstanceSetterComp* setter = new InstanceSetterComp(node,
-                                                      placeholder,
                                                       for_receiver.value(),
                                                       for_value.value());
   ReturnComputation(setter);
@@ -587,17 +582,7 @@ void EffectGraphVisitor::VisitLoadIndexedNode(LoadIndexedNode* node) {
 
 
 void EffectGraphVisitor::VisitStoreIndexedNode(StoreIndexedNode* node) {
-  // This is not a straight instance call to e0.[]=(e1, e2), it is a
-  // call to
-  //
-  // (a, i, v) { a.[]=(i, v); return v; }(e0, e1, e2)
-  //
-  // Without constructing that function, we simulate it at the IL
-  // level by preallocating a slot for the return value.
-  const Smi& zero = Smi::ZoneHandle(Smi::New(0));
-  AddInstruction(new BindInstr(temp_index(), new ConstantVal(zero)));
-  TempVal* placeholder = new TempVal(temp_index());
-  ArgumentGraphVisitor for_array(owner(), temp_index() + 1);
+  ArgumentGraphVisitor for_array(owner(), temp_index());
   node->array()->Visit(&for_array);
   Append(for_array);
   ArgumentGraphVisitor for_index(owner(), for_array.temp_index());
@@ -607,7 +592,6 @@ void EffectGraphVisitor::VisitStoreIndexedNode(StoreIndexedNode* node) {
   node->value()->Visit(&for_value);
   Append(for_value);
   StoreIndexedComp* store = new StoreIndexedComp(node,
-                                                 placeholder,
                                                  for_array.value(),
                                                  for_index.value(),
                                                  for_value.value());
@@ -774,8 +758,6 @@ void FlowGraphPrinter::VisitNativeCall(NativeCallComp* comp) {
 
 void FlowGraphPrinter::VisitStoreIndexed(StoreIndexedComp* comp) {
   OS::Print("StoreIndexed(");
-  comp->placeholder()->Accept(this);
-  OS::Print(", ");
   comp->array()->Accept(this);
   OS::Print(", ");
   comp->index()->Accept(this);
@@ -787,8 +769,6 @@ void FlowGraphPrinter::VisitStoreIndexed(StoreIndexedComp* comp) {
 
 void FlowGraphPrinter::VisitInstanceSetter(InstanceSetterComp* comp) {
   OS::Print("InstanceSetter(");
-  comp->placeholder()->Accept(this);
-  OS::Print(", ");
   comp->receiver()->Accept(this);
   OS::Print(", ");
   comp->value()->Accept(this);