Move some Pop/Drop calls directly to the places where they are needed.

src/hydrogen.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 5052 matching lines @@
 
   // No luck, do a generic store.
   return BuildStoreNamedGeneric(object, name, value);
 }
 
 
 void HGraphBuilder::HandlePolymorphicLoadNamedField(Property* expr,
                                                     HValue* object,
                                                     SmallMapList* types,
                                                     Handle<String> name) {
+  AddInstruction(new(zone()) HCheckNonSmi(object));

[Michael Starzinger, 2012/07/27 12:26:03]

Can we move this down right in front of the block where instructions are
actually emitted? Because this first block is just checking some optimistic
assumptions but not generating any instructions.

[Sven Panne, 2012/07/27 12:35:30]

Done.

   int count = 0;
   int previous_field_offset = 0;
   bool previous_field_is_in_object = false;
   bool is_monomorphic_field = true;
   Handle<Map> map;
   LookupResult lookup(isolate());
   for (int i = 0; i < types->length() && count < kMaxLoadPolymorphism; ++i) {
     map = types->at(i);
     if (ComputeLoadStoreField(map, name, &lookup, false)) {
       int index = ComputeLoadStoreFieldIndex(map, name, &lookup);
@@ skipping 112 matching lines @@
   if (!ast_context()->IsEffect()) return ast_context()->ReturnValue(Pop());
 }
 
 
 void HGraphBuilder::HandlePropertyAssignment(Assignment* expr) {
   Property* prop = expr->target()->AsProperty();
   ASSERT(prop != NULL);
   expr->RecordTypeFeedback(oracle(), zone());
   CHECK_ALIVE(VisitForValue(prop->obj()));
 
-  HValue* value = NULL;
-  HInstruction* instr = NULL;
-
   if (prop->key()->IsPropertyName()) {
     // Named store.
     CHECK_ALIVE(VisitForValue(expr->value()));
-    value = Pop();
-    HValue* object = Pop();
+    HValue* value = environment()->ExpressionStackAt(0);
+    HValue* object = environment()->ExpressionStackAt(1);
 
     Literal* key = prop->key()->AsLiteral();
     Handle<String> name = Handle<String>::cast(key->handle());
     ASSERT(!name.is_null());
 
+    HInstruction* instr = NULL;
     SmallMapList* types = expr->GetReceiverTypes();
     if (expr->IsMonomorphic()) {
       Handle<Map> map = types->first();
       Handle<AccessorPair> accessors;
       Handle<JSObject> holder;
       if (LookupAccessorPair(map, name, &accessors, &holder)) {
+        Drop(2);
         instr = BuildCallSetter(object, value, map, accessors, holder);
       } else {
+        Drop(2);
         CHECK_ALIVE(instr = BuildStoreNamedMonomorphic(object,
                                                        name,
                                                        value,
                                                        map));
       }
+
     } else if (types != NULL && types->length() > 1) {
-      HandlePolymorphicStoreNamedField(expr, object, value, types, name);
-      return;
-
+      Drop(2);
+      return HandlePolymorphicStoreNamedField(expr, object, value, types, name);
     } else {
+      Drop(2);
       instr = BuildStoreNamedGeneric(object, name, value);
     }
 
+    Push(value);
+    instr->set_position(expr->position());
+    AddInstruction(instr);
+    if (instr->HasObservableSideEffects()) AddSimulate(expr->AssignmentId());
+    return ast_context()->ReturnValue(Pop());
+
   } else {
     // Keyed store.
     CHECK_ALIVE(VisitForValue(prop->key()));
     CHECK_ALIVE(VisitForValue(expr->value()));
-    value = Pop();
+    HValue* value = Pop();
     HValue* key = Pop();
     HValue* object = Pop();
     bool has_side_effects = false;
     HandleKeyedElementAccess(object, key, value, expr, expr->AssignmentId(),
                              expr->position(),
                              true,  // is_store
                              &has_side_effects);
     Push(value);
     ASSERT(has_side_effects);  // Stores always have side effects.
     AddSimulate(expr->AssignmentId());
     return ast_context()->ReturnValue(Pop());
   }
-  Push(value);
-  instr->set_position(expr->position());
-  AddInstruction(instr);
-  if (instr->HasObservableSideEffects()) AddSimulate(expr->AssignmentId());
-  return ast_context()->ReturnValue(Pop());
 }
 
 
 // Because not every expression has a position and there is not common
 // superclass of Assignment and CountOperation, we cannot just pass the
 // owning expression instead of position and ast_id separately.
 void HGraphBuilder::HandleGlobalVariableAssignment(Variable* var,
                                                    HValue* value,
                                                    int position,
                                                    int ast_id) {
@@ skipping 1066 matching lines @@
 
   } else if (expr->IsFunctionPrototype()) {
     HValue* function = Pop();
     AddInstruction(new(zone()) HCheckNonSmi(function));
     instr = new(zone()) HLoadFunctionPrototype(function);
 
   } else if (expr->key()->IsPropertyName()) {
     Handle<String> name = expr->key()->AsLiteral()->AsPropertyName();
     SmallMapList* types = expr->GetReceiverTypes();
 
-    HValue* obj = Pop();
     if (expr->IsMonomorphic()) {
       Handle<Map> map = types->first();
       Handle<AccessorPair> accessors;
       Handle<JSObject> holder;
       if (LookupAccessorPair(map, name, &accessors, &holder)) {
-        instr = BuildCallGetter(obj, map, accessors, holder);
+        instr = BuildCallGetter(Pop(), map, accessors, holder);
       } else {
-        instr = BuildLoadNamedMonomorphic(obj, name, expr, map);
+        instr = BuildLoadNamedMonomorphic(Pop(), name, expr, map);
       }
     } else if (types != NULL && types->length() > 1) {
-      AddInstruction(new(zone()) HCheckNonSmi(obj));
-      HandlePolymorphicLoadNamedField(expr, obj, types, name);
-      return;
+      return HandlePolymorphicLoadNamedField(expr, Pop(), types, name);
     } else {
-      instr = BuildLoadNamedGeneric(obj, name, expr);
+      instr = BuildLoadNamedGeneric(Pop(), name, expr);
     }
 
   } else {
     CHECK_ALIVE(VisitForValue(expr->key()));
 
     HValue* key = Pop();
     HValue* obj = Pop();
 
     bool has_side_effects = false;
     HValue* load = HandleKeyedElementAccess(
@@ skipping 3270 matching lines @@
     }
   }
 
 #ifdef DEBUG
   if (graph_ != NULL) graph_->Verify(false);  // No full verify.
   if (allocator_ != NULL) allocator_->Verify();
 #endif
 }
 
 } }  // namespace v8::internal