First step in letting Crankshaft inline functions with a different context.

src/hydrogen.cc

 // Copyright 2011 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 230 matching lines @@
 
 
 void HBasicBlock::RegisterPredecessor(HBasicBlock* pred) {
   if (HasPredecessor()) {
     // Only loop header blocks can have a predecessor added after
     // instructions have been added to the block (they have phis for all
     // values in the environment, these phis may be eliminated later).
     ASSERT(IsLoopHeader() || first_ == NULL);
     HEnvironment* incoming_env = pred->last_environment();
     if (IsLoopHeader()) {
-      ASSERT(phis()->length() == incoming_env->length());
-      for (int i = 0; i < phis_.length(); ++i) {
-        phis_[i]->AddInput(incoming_env->values()->at(i));
+      int phi_index = 0;
+      for (int i = 0; i < incoming_env->length(); ++i) {
+          phis_[phi_index++]->AddInput(incoming_env->values()->at(i));
       }
+      ASSERT_EQ(phi_index, phis_.length());
     } else {
       last_environment()->AddIncomingEdge(this, pred->last_environment());
     }
   } else if (!HasEnvironment() && !IsFinished()) {
     ASSERT(!IsLoopHeader());
     SetInitialEnvironment(pred->last_environment()->Copy());
   }
 
   predecessors_.Add(pred);
 }
@@ skipping 1957 matching lines @@
   // We don't yet handle the function name for named function expressions.
   if (scope->function() != NULL) return Bailout("named function expression");
 
   HConstant* undefined_constant = new(zone()) HConstant(
       isolate()->factory()->undefined_value(), Representation::Tagged());
   AddInstruction(undefined_constant);
   graph_->set_undefined_constant(undefined_constant);
 
   // Set the initial values of parameters including "this".  "This" has
   // parameter index 0.
-  int count = scope->num_parameters() + 1;
-  for (int i = 0; i < count; ++i) {
+  ASSERT_EQ(scope->num_parameters() + 1, environment()->parameter_count());
+
+  for (int i = 0; i < environment()->parameter_count(); ++i) {
     HInstruction* parameter = AddInstruction(new(zone()) HParameter(i));
     environment()->Bind(i, parameter);
   }
 
-  // Set the initial values of stack-allocated locals.
-  for (int i = count; i < environment()->length(); ++i) {
+  // First special is HContext.
+  HInstruction* context = AddInstruction(new(zone()) HContext());

[Kevin Millikin (Chromium), 2011/05/06 12:29:45]

I like to write new(zone()) HContext.

+  environment()->Bind(environment()->parameter_count(), context);

[Kevin Millikin (Chromium), 2011/05/06 12:29:45]

environment()->BindContext(context)

+
+  // Initialize specials and locals to undefined.
+  for (int i = environment()->parameter_count() + 1;
+       i < environment()->length();
+       ++i) {
     environment()->Bind(i, undefined_constant);
   }
 
   // Handle the arguments and arguments shadow variables specially (they do
   // not have declarations).
   if (scope->arguments() != NULL) {
     if (!scope->arguments()->IsStackAllocated() ||
         (scope->arguments_shadow() != NULL &&
         !scope->arguments_shadow()->IsStackAllocated())) {
       return Bailout("context-allocated arguments");
@@ skipping 337 matching lines @@
   current_block()->Finish(test);
 
   HBasicBlock* loop_predecessor = graph()->CreateBasicBlock();
   non_osr_entry->Goto(loop_predecessor);
 
   set_current_block(osr_entry);
   int osr_entry_id = statement->OsrEntryId();
   // We want the correct environment at the OsrEntry instruction.  Build
   // it explicitly.  The expression stack should be empty.
   int count = environment()->length();
-  ASSERT(count ==
-         (environment()->parameter_count() + environment()->local_count()));
+  ASSERT(count == (environment()->parameter_count() +

[Kevin Millikin (Chromium), 2011/05/06 12:29:45]

ASSERT(environment()->ExpressionStackIsEmpty())

+                   environment()->specials_count() +
+                   environment()->local_count()));
   for (int i = 0; i < count; ++i) {
-    HUnknownOSRValue* unknown = new(zone()) HUnknownOSRValue;
-    AddInstruction(unknown);
-    environment()->Bind(i, unknown);
+    HUnknownOSRValue* osr_value = new(zone()) HUnknownOSRValue;
+    AddInstruction(osr_value);
+    environment()->Bind(i, osr_value);
   }
 
   AddSimulate(osr_entry_id);
   AddInstruction(new(zone()) HOsrEntry(osr_entry_id));
+  HContext* context = new(zone()) HContext;
+  AddInstruction(context);
+  environment()->Bind(environment()->parameter_count(), context);

[Kevin Millikin (Chromium), 2011/05/06 12:29:45]

environment()->BindContext(context)

   current_block()->Goto(loop_predecessor);
   loop_predecessor->SetJoinId(statement->EntryId());
   set_current_block(loop_predecessor);
 }
 
 
 void HGraphBuilder::VisitDoWhileStatement(DoWhileStatement* stmt) {
   ASSERT(!HasStackOverflow());
   ASSERT(current_block() != NULL);
   ASSERT(current_block()->HasPredecessor());
@@ skipping 262 matching lines @@
       lookup->holder() != *global) {
     return kUseGeneric;
   }
 
   return kUseCell;
 }
 
 
 HValue* HGraphBuilder::BuildContextChainWalk(Variable* var) {
   ASSERT(var->IsContextSlot());
-  HInstruction* context = new(zone()) HContext;
-  AddInstruction(context);
+  HValue* context = environment()->LookupContext();
   int length = info()->scope()->ContextChainLength(var->scope());
   while (length-- > 0) {
-    context = new(zone()) HOuterContext(context);
-    AddInstruction(context);
+    HInstruction* context_instruction = new(zone()) HOuterContext(context);
+    AddInstruction(context_instruction);
+    context = context_instruction;
   }
   return context;
 }
 
 
 void HGraphBuilder::VisitVariableProxy(VariableProxy* expr) {
   ASSERT(!HasStackOverflow());
   ASSERT(current_block() != NULL);
   ASSERT(current_block()->HasPredecessor());
   Variable* variable = expr->AsVariable();
@@ skipping 18 matching lines @@
       type = kUseGeneric;
     }
 
     if (type == kUseCell) {
       Handle<GlobalObject> global(info()->global_object());
       Handle<JSGlobalPropertyCell> cell(global->GetPropertyCell(&lookup));
       bool check_hole = !lookup.IsDontDelete() || lookup.IsReadOnly();
       HLoadGlobalCell* instr = new(zone()) HLoadGlobalCell(cell, check_hole);
       ast_context()->ReturnInstruction(instr, expr->id());
     } else {
-      HContext* context = new(zone()) HContext;
-      AddInstruction(context);
+      HValue* context = environment()->LookupContext();
       HGlobalObject* global_object = new(zone()) HGlobalObject(context);
       AddInstruction(global_object);
       HLoadGlobalGeneric* instr =
           new(zone()) HLoadGlobalGeneric(context,
                                          global_object,
                                          variable->name(),
                                          ast_context()->is_for_typeof());
       instr->set_position(expr->position());
       ASSERT(instr->HasSideEffects());
       ast_context()->ReturnInstruction(instr, expr->id());
@@ skipping 22 matching lines @@
                                                      expr->flags(),
                                                      expr->literal_index());
   ast_context()->ReturnInstruction(instr, expr->id());
 }
 
 
 void HGraphBuilder::VisitObjectLiteral(ObjectLiteral* expr) {
   ASSERT(!HasStackOverflow());
   ASSERT(current_block() != NULL);
   ASSERT(current_block()->HasPredecessor());
-  HContext* context = new(zone()) HContext;
-  AddInstruction(context);
+  HValue* context = environment()->LookupContext();
   HObjectLiteral* literal =
       new(zone()) HObjectLiteral(context,
                                  expr->constant_properties(),
                                  expr->fast_elements(),
                                  expr->literal_index(),
                                  expr->depth(),
                                  expr->has_function());
   // The object is expected in the bailout environment during computation
   // of the property values and is the value of the entire expression.
   PushAndAdd(literal);
@@ skipping 161 matching lines @@
     // enable elimination of redundant checks after the transition store.
     instr->SetFlag(HValue::kChangesMaps);
   }
   return instr;
 }
 
 
 HInstruction* HGraphBuilder::BuildStoreNamedGeneric(HValue* object,
                                                     Handle<String> name,
                                                     HValue* value) {
-  HContext* context = new(zone()) HContext;
-  AddInstruction(context);
+  HValue* context = environment()->LookupContext();
   return new(zone()) HStoreNamedGeneric(
                          context,
                          object,
                          name,
                          value,
                          function_strict_mode());
 }
 
 
 HInstruction* HGraphBuilder::BuildStoreNamed(HValue* object,
@@ skipping 155 matching lines @@
   GlobalPropertyAccess type = LookupGlobalProperty(var, &lookup, true);
   if (type == kUseCell) {
     bool check_hole = !lookup.IsDontDelete() || lookup.IsReadOnly();
     Handle<GlobalObject> global(info()->global_object());
     Handle<JSGlobalPropertyCell> cell(global->GetPropertyCell(&lookup));
     HInstruction* instr = new(zone()) HStoreGlobalCell(value, cell, check_hole);
     instr->set_position(position);
     AddInstruction(instr);
     if (instr->HasSideEffects()) AddSimulate(ast_id);
   } else {
-    HContext* context = new(zone()) HContext;
-    AddInstruction(context);
+    HValue* context =  environment()->LookupContext();
     HGlobalObject* global_object = new(zone()) HGlobalObject(context);
     AddInstruction(global_object);
     HStoreGlobalGeneric* instr =
         new(zone()) HStoreGlobalGeneric(context,
                                         global_object,
                                         var->name(),
                                         value,
                                         function_strict_mode());
     instr->set_position(position);
     AddInstruction(instr);
@@ skipping 204 matching lines @@
     int offset = (index * kPointerSize) + FixedArray::kHeaderSize;
     return new(zone()) HLoadNamedField(object, false, offset);
   }
 }
 
 
 HInstruction* HGraphBuilder::BuildLoadNamedGeneric(HValue* obj,
                                                    Property* expr) {
   ASSERT(expr->key()->IsPropertyName());
   Handle<Object> name = expr->key()->AsLiteral()->handle();
-  HContext* context = new(zone()) HContext;
-  AddInstruction(context);
+  HValue* context = environment()->LookupContext();
   return new(zone()) HLoadNamedGeneric(context, obj, name);
 }
 
 
 HInstruction* HGraphBuilder::BuildLoadNamed(HValue* obj,
                                             Property* expr,
                                             Handle<Map> map,
                                             Handle<String> name) {
   LookupResult lookup;
   map->LookupInDescriptors(NULL, *name, &lookup);
   if (lookup.IsProperty() && lookup.type() == FIELD) {
     return BuildLoadNamedField(obj,
                                expr,
                                map,
                                &lookup,
                                true);
   } else if (lookup.IsProperty() && lookup.type() == CONSTANT_FUNCTION) {
     AddInstruction(new(zone()) HCheckNonSmi(obj));
     AddInstruction(new(zone()) HCheckMap(obj, map));
     Handle<JSFunction> function(lookup.GetConstantFunctionFromMap(*map));
     return new(zone()) HConstant(function, Representation::Tagged());
   } else {
     return BuildLoadNamedGeneric(obj, expr);
   }
 }
 
 
 HInstruction* HGraphBuilder::BuildLoadKeyedGeneric(HValue* object,
                                                    HValue* key) {
-  HContext* context = new(zone()) HContext;
-  AddInstruction(context);
+  HValue* context = environment()->LookupContext();
   return new(zone()) HLoadKeyedGeneric(context, object, key);
 }
 
 
 HInstruction* HGraphBuilder::BuildLoadKeyedFastElement(HValue* object,
                                                        HValue* key,
                                                        Property* expr) {
   ASSERT(!expr->key()->IsPropertyName() && expr->IsMonomorphic());
   AddInstruction(new(zone()) HCheckNonSmi(object));
   Handle<Map> map = expr->GetMonomorphicReceiverType();
@@ skipping 54 matching lines @@
       return BuildLoadKeyedFastElement(obj, key, prop);
     }
   }
   return BuildLoadKeyedGeneric(obj, key);
 }
 
 
 HInstruction* HGraphBuilder::BuildStoreKeyedGeneric(HValue* object,
                                                     HValue* key,
                                                     HValue* value) {
-  HContext* context = new(zone()) HContext;
-  AddInstruction(context);
+  HValue* context = environment()->LookupContext();
   return new(zone()) HStoreKeyedGeneric(
                          context,
                          object,
                          key,
                          value,
                          function_strict_mode());
 }
 
 
 HInstruction* HGraphBuilder::BuildStoreKeyedFastElement(HValue* object,
@@ skipping 232 matching lines @@
       set_current_block(if_false);
     }
   }
 
   // Finish up.  Unconditionally deoptimize if we've handled all the maps we
   // know about and do not want to handle ones we've never seen.  Otherwise
   // use a generic IC.
   if (count == types->length() && FLAG_deoptimize_uncommon_cases) {
     current_block()->FinishExitWithDeoptimization();
   } else {
-    HContext* context = new(zone()) HContext;
-    AddInstruction(context);
+    HValue* context = environment()->LookupContext();
     HCallNamed* call = new(zone()) HCallNamed(context, name, argument_count);
     call->set_position(expr->position());
     PreProcessCall(call);
 
     if (join != NULL) {
       AddInstruction(call);
       if (!ast_context()->IsEffect()) Push(call);
       current_block()->Goto(join);
     } else {
       ast_context()->ReturnInstruction(call, expr->id());
@@ skipping 173 matching lines @@
       environment()->CopyForInlining(target,
                                      function,
                                      HEnvironment::HYDROGEN,
                                      undefined);
   HBasicBlock* body_entry = CreateBasicBlock(inner_env);
   current_block()->Goto(body_entry);
 
   body_entry->SetJoinId(expr->ReturnId());
   set_current_block(body_entry);
   AddInstruction(new(zone()) HEnterInlined(target, function));
+  // AddInstruction(environment()->LookupContext());

[Kevin Millikin (Chromium), 2011/05/06 12:29:45]

Remove me.

   VisitStatements(function->body());
   if (HasStackOverflow()) {
     // Bail out if the inline function did, as we cannot residualize a call
     // instead.
     TraceInline(target, "inline graph construction failed");
     return true;
   }
 
   // Update inlined nodes count.
   inlined_count_ += nodes_added;
@@ skipping 213 matching lines @@
 
       CHECK_ALIVE(VisitForValue(prop->key()));
       // Push receiver and key like the non-optimized code generator expects it.
       HValue* key = Pop();
       HValue* receiver = Pop();
       Push(key);
       Push(receiver);
 
       CHECK_ALIVE(VisitExpressions(expr->arguments()));
 
-      HContext* context = new(zone()) HContext;
-      AddInstruction(context);
+      HValue* context = environment()->LookupContext();
       call = PreProcessCall(
           new(zone()) HCallKeyed(context, key, argument_count));
       call->set_position(expr->position());
       Drop(1);  // Key.
       ast_context()->ReturnInstruction(call, expr->id());
       return;
     }
 
     // Named function call.
     expr->RecordTypeFeedback(oracle());
@@ skipping 18 matching lines @@
                                    receiver_map,
                                    expr->check_type())) {
         return;
       }
 
       if (CallStubCompiler::HasCustomCallGenerator(*expr->target()) ||
           expr->check_type() != RECEIVER_MAP_CHECK) {
         // When the target has a custom call IC generator, use the IC,
         // because it is likely to generate better code.  Also use the IC
         // when a primitive receiver check is required.
-        HContext* context = new(zone()) HContext;
-        AddInstruction(context);
+        HValue* context = environment()->LookupContext();
         call = PreProcessCall(
             new(zone()) HCallNamed(context, name, argument_count));
       } else {
         AddCheckConstantFunction(expr, receiver, receiver_map, true);
 
         if (TryInline(expr)) return;
         call = PreProcessCall(
             new(zone()) HCallConstantFunction(expr->target(),
                                               argument_count));
       }
     } else if (types != NULL && types->length() > 1) {
       ASSERT(expr->check_type() == RECEIVER_MAP_CHECK);
       HandlePolymorphicCallNamed(expr, receiver, types, name);
       return;
 
     } else {
-      HContext* context = new(zone()) HContext;
-      AddInstruction(context);
+      HValue* context = environment()->LookupContext();
       call = PreProcessCall(
           new(zone()) HCallNamed(context, name, argument_count));
     }
 
   } else {
     Variable* var = expr->expression()->AsVariableProxy()->AsVariable();
     bool global_call = (var != NULL) && var->is_global() && !var->is_this();
 
     if (!global_call) {
       ++argument_count;
       CHECK_ALIVE(VisitForValue(expr->expression()));
     }
 
     if (global_call) {
       bool known_global_function = false;
       // If there is a global property cell for the name at compile time and
       // access check is not enabled we assume that the function will not change
       // and generate optimized code for calling the function.
       LookupResult lookup;
       GlobalPropertyAccess type = LookupGlobalProperty(var, &lookup, false);
       if (type == kUseCell &&
           !info()->global_object()->IsAccessCheckNeeded()) {
         Handle<GlobalObject> global(info()->global_object());
         known_global_function = expr->ComputeGlobalTarget(global, &lookup);
       }
       if (known_global_function) {
         // Push the global object instead of the global receiver because
         // code generated by the full code generator expects it.
-        HContext* context = new(zone()) HContext;
+        HValue* context = environment()->LookupContext();
         HGlobalObject* global_object = new(zone()) HGlobalObject(context);
-        AddInstruction(context);
         PushAndAdd(global_object);
         CHECK_ALIVE(VisitExpressions(expr->arguments()));
 
         CHECK_ALIVE(VisitForValue(expr->expression()));
         HValue* function = Pop();
         AddInstruction(new(zone()) HCheckFunction(function, expr->target()));
 
         // Replace the global object with the global receiver.
         HGlobalReceiver* global_receiver =
             new(zone()) HGlobalReceiver(global_object);
         // Index of the receiver from the top of the expression stack.
         const int receiver_index = argument_count - 1;
         AddInstruction(global_receiver);
         ASSERT(environment()->ExpressionStackAt(receiver_index)->
                IsGlobalObject());
         environment()->SetExpressionStackAt(receiver_index, global_receiver);
 
         if (TryInline(expr)) return;
         call = PreProcessCall(new(zone()) HCallKnownGlobal(expr->target(),
                                                            argument_count));
       } else {
-        HContext* context = new(zone()) HContext;
-        AddInstruction(context);
+        HValue* context = environment()->LookupContext();
         PushAndAdd(new(zone()) HGlobalObject(context));
         CHECK_ALIVE(VisitExpressions(expr->arguments()));
 
         call = PreProcessCall(new(zone()) HCallGlobal(context,
                                               var->name(),
                                               argument_count));
       }
 
     } else {
-      HContext* context = new(zone()) HContext;
+      HValue* context = environment()->LookupContext();
       HGlobalObject* global_object = new(zone()) HGlobalObject(context);
-      AddInstruction(context);
       AddInstruction(global_object);
       PushAndAdd(new(zone()) HGlobalReceiver(global_object));
       CHECK_ALIVE(VisitExpressions(expr->arguments()));
 
       call = PreProcessCall(new(zone()) HCallFunction(context, argument_count));
     }
   }
 
   call->set_position(expr->position());
   ast_context()->ReturnInstruction(call, expr->id());
 }
 
 
 void HGraphBuilder::VisitCallNew(CallNew* expr) {
   ASSERT(!HasStackOverflow());
   ASSERT(current_block() != NULL);
   ASSERT(current_block()->HasPredecessor());
   // The constructor function is also used as the receiver argument to the
   // JS construct call builtin.
   CHECK_ALIVE(VisitForValue(expr->expression()));
   CHECK_ALIVE(VisitExpressions(expr->arguments()));
 
-  HContext* context = new(zone()) HContext;
-  AddInstruction(context);
+  HValue* context = environment()->LookupContext();
 
   // The constructor is both an operand to the instruction and an argument
   // to the construct call.
   int arg_count = expr->arguments()->length() + 1;  // Plus constructor.
   HValue* constructor = environment()->ExpressionStackAt(arg_count - 1);
   HCallNew* call = new(zone()) HCallNew(context, constructor, arg_count);
   call->set_position(expr->position());
   PreProcessCall(call);
   ast_context()->ReturnInstruction(call, expr->id());
 }
@@ skipping 602 matching lines @@
         // change and thus prefer the general IC code.
         if (!isolate()->heap()->InNewSpace(*candidate)) {
           target = candidate;
         }
       }
     }
 
     // If the target is not null we have found a known global function that is
     // assumed to stay the same for this instanceof.
     if (target.is_null()) {
-      HContext* context = new(zone()) HContext;
-      AddInstruction(context);
+      HValue* context = environment()->LookupContext();
       instr = new(zone()) HInstanceOf(context, left, right);
     } else {
       AddInstruction(new(zone()) HCheckFunction(right, target));
       instr = new(zone()) HInstanceOfKnownGlobal(left, target);
     }
   } else if (op == Token::IN) {
     instr = new(zone()) HIn(left, right);
   } else if (type_info.IsNonPrimitive()) {
     switch (op) {
       case Token::EQ:
@@ skipping 255 matching lines @@
 // Fast support for Math.random().
 void HGraphBuilder::GenerateRandomHeapNumber(CallRuntime* call) {
   return Bailout("inlined runtime function: RandomHeapNumber");
 }
 
 
 // Fast support for StringAdd.
 void HGraphBuilder::GenerateStringAdd(CallRuntime* call) {
   ASSERT_EQ(2, call->arguments()->length());
   CHECK_ALIVE(VisitArgumentList(call->arguments()));
-  HContext* context = new(zone()) HContext;
-  AddInstruction(context);
+  HValue* context = environment()->LookupContext();
   HCallStub* result = new(zone()) HCallStub(context, CodeStub::StringAdd, 2);
   Drop(2);
   ast_context()->ReturnInstruction(result, call->id());
 }
 
 
 // Fast support for SubString.
 void HGraphBuilder::GenerateSubString(CallRuntime* call) {
   ASSERT_EQ(3, call->arguments()->length());
   CHECK_ALIVE(VisitArgumentList(call->arguments()));
-  HContext* context = new(zone()) HContext;
-  AddInstruction(context);
+  HValue* context = environment()->LookupContext();
   HCallStub* result = new(zone()) HCallStub(context, CodeStub::SubString, 3);
   Drop(3);
   ast_context()->ReturnInstruction(result, call->id());
 }
 
 
 // Fast support for StringCompare.
 void HGraphBuilder::GenerateStringCompare(CallRuntime* call) {
   ASSERT_EQ(2, call->arguments()->length());
   CHECK_ALIVE(VisitArgumentList(call->arguments()));
-  HContext* context = new(zone()) HContext;
-  AddInstruction(context);
+  HValue* context = environment()->LookupContext();
   HCallStub* result =
       new(zone()) HCallStub(context, CodeStub::StringCompare, 2);
   Drop(2);
   ast_context()->ReturnInstruction(result, call->id());
 }
 
 
 // Support for direct calls from JavaScript to native RegExp code.
 void HGraphBuilder::GenerateRegExpExec(CallRuntime* call) {
   ASSERT_EQ(4, call->arguments()->length());
   CHECK_ALIVE(VisitArgumentList(call->arguments()));
-  HContext* context = new(zone()) HContext;
-  AddInstruction(context);
+  HValue* context = environment()->LookupContext();
   HCallStub* result = new(zone()) HCallStub(context, CodeStub::RegExpExec, 4);
   Drop(4);
   ast_context()->ReturnInstruction(result, call->id());
 }
 
 
 // Construct a RegExp exec result with two in-object properties.
 void HGraphBuilder::GenerateRegExpConstructResult(CallRuntime* call) {
   ASSERT_EQ(3, call->arguments()->length());
   CHECK_ALIVE(VisitArgumentList(call->arguments()));
-  HContext* context = new(zone()) HContext;
-  AddInstruction(context);
+  HValue* context = environment()->LookupContext();
   HCallStub* result =
       new(zone()) HCallStub(context, CodeStub::RegExpConstructResult, 3);
   Drop(3);
   ast_context()->ReturnInstruction(result, call->id());
 }
 
 
 // Support for fast native caches.
 void HGraphBuilder::GenerateGetFromCache(CallRuntime* call) {
   return Bailout("inlined runtime function: GetFromCache");
 }
 
 
 // Fast support for number to string.
 void HGraphBuilder::GenerateNumberToString(CallRuntime* call) {
   ASSERT_EQ(1, call->arguments()->length());
   CHECK_ALIVE(VisitArgumentList(call->arguments()));
-  HContext* context = new(zone()) HContext;
-  AddInstruction(context);
+  HValue* context = environment()->LookupContext();
   HCallStub* result =
       new(zone()) HCallStub(context, CodeStub::NumberToString, 1);
   Drop(1);
   ast_context()->ReturnInstruction(result, call->id());
 }
 
 
 // Fast swapping of elements. Takes three expressions, the object and two
 // indices. This should only be used if the indices are known to be
 // non-negative and within bounds of the elements array at the call site.
 void HGraphBuilder::GenerateSwapElements(CallRuntime* call) {
   return Bailout("inlined runtime function: SwapElements");
 }
 
 
 // Fast call for custom callbacks.
 void HGraphBuilder::GenerateCallFunction(CallRuntime* call) {
   // 1 ~ The function to call is not itself an argument to the call.
   int arg_count = call->arguments()->length() - 1;
   ASSERT(arg_count >= 1);  // There's always at least a receiver.
 
   for (int i = 0; i < arg_count; ++i) {
     CHECK_ALIVE(VisitArgument(call->arguments()->at(i)));
   }
   CHECK_ALIVE(VisitForValue(call->arguments()->last()));
   HValue* function = Pop();
-  HContext* context = new HContext;
-  AddInstruction(context);
+  HValue* context = environment()->LookupContext();
   HInvokeFunction* result =
       new(zone()) HInvokeFunction(context, function, arg_count);
   Drop(arg_count);
   ast_context()->ReturnInstruction(result, call->id());
 }
 
 
 // Fast call to math functions.
 void HGraphBuilder::GenerateMathPow(CallRuntime* call) {
   ASSERT_EQ(2, call->arguments()->length());
   CHECK_ALIVE(VisitForValue(call->arguments()->at(0)));
   CHECK_ALIVE(VisitForValue(call->arguments()->at(1)));
   HValue* right = Pop();
   HValue* left = Pop();
   HPower* result = new(zone()) HPower(left, right);
   ast_context()->ReturnInstruction(result, call->id());
 }
 
 
 void HGraphBuilder::GenerateMathSin(CallRuntime* call) {
   ASSERT_EQ(1, call->arguments()->length());
   CHECK_ALIVE(VisitArgumentList(call->arguments()));
-  HContext* context = new(zone()) HContext;
-  AddInstruction(context);
+  HValue* context = environment()->LookupContext();
   HCallStub* result =
       new(zone()) HCallStub(context, CodeStub::TranscendentalCache, 1);
   result->set_transcendental_type(TranscendentalCache::SIN);
   Drop(1);
   ast_context()->ReturnInstruction(result, call->id());
 }
 
 
 void HGraphBuilder::GenerateMathCos(CallRuntime* call) {
   ASSERT_EQ(1, call->arguments()->length());
   CHECK_ALIVE(VisitArgumentList(call->arguments()));
-  HContext* context = new(zone()) HContext;
-  AddInstruction(context);
+  HValue* context = environment()->LookupContext();
   HCallStub* result =
       new(zone()) HCallStub(context, CodeStub::TranscendentalCache, 1);
   result->set_transcendental_type(TranscendentalCache::COS);
   Drop(1);
   ast_context()->ReturnInstruction(result, call->id());
 }
 
 
 void HGraphBuilder::GenerateMathLog(CallRuntime* call) {
   ASSERT_EQ(1, call->arguments()->length());
   CHECK_ALIVE(VisitArgumentList(call->arguments()));
-  HContext* context = new(zone()) HContext;
-  AddInstruction(context);
+  HValue* context = environment()->LookupContext();
   HCallStub* result =
       new(zone()) HCallStub(context, CodeStub::TranscendentalCache, 1);
   result->set_transcendental_type(TranscendentalCache::LOG);
   Drop(1);
   ast_context()->ReturnInstruction(result, call->id());
 }
 
 
 void HGraphBuilder::GenerateMathSqrt(CallRuntime* call) {
   return Bailout("inlined runtime function: MathSqrt");
@@ skipping 24 matching lines @@
 #undef CHECK_ALIVE
 
 
 HEnvironment::HEnvironment(HEnvironment* outer,
                            Scope* scope,
                            Handle<JSFunction> closure)
     : closure_(closure),
       values_(0),
       assigned_variables_(4),
       parameter_count_(0),
+      specials_count_(1),
       local_count_(0),
       outer_(outer),
       pop_count_(0),
       push_count_(0),
       ast_id_(AstNode::kNoNumber) {
   Initialize(scope->num_parameters() + 1, scope->num_stack_slots(), 0);
 }
 
 
 HEnvironment::HEnvironment(const HEnvironment* other)
     : values_(0),
       assigned_variables_(0),
       parameter_count_(0),
+      specials_count_(1),
       local_count_(0),
       outer_(NULL),
       pop_count_(0),
       push_count_(0),
       ast_id_(other->ast_id()) {
   Initialize(other);
 }
 
 
 void HEnvironment::Initialize(int parameter_count,
                               int local_count,
                               int stack_height) {
   parameter_count_ = parameter_count;
   local_count_ = local_count;
 
   // Avoid reallocating the temporaries' backing store on the first Push.
-  int total = parameter_count + local_count + stack_height;
+  int total = parameter_count + specials_count_ + local_count + stack_height;
   values_.Initialize(total + 4);
   for (int i = 0; i < total; ++i) values_.Add(NULL);
 }
 
 
 void HEnvironment::Initialize(const HEnvironment* other) {
   closure_ = other->closure();
   values_.AddAll(other->values_);
   assigned_variables_.AddAll(other->assigned_variables_);
   parameter_count_ = other->parameter_count_;
@@ skipping 38 matching lines @@
 void HEnvironment::Bind(int index, HValue* value) {
   ASSERT(value != NULL);
   if (!assigned_variables_.Contains(index)) {
     assigned_variables_.Add(index);
   }
   values_[index] = value;
 }
 
 
 bool HEnvironment::HasExpressionAt(int index) const {
-  return index >= parameter_count_ + local_count_;
+  return index >= parameter_count_ + specials_count_ + local_count_;
 }
 
 
 bool HEnvironment::ExpressionStackIsEmpty() const {
-  int first_expression = parameter_count() + local_count();
+  int first_expression = parameter_count() + specials_count() + local_count();
   ASSERT(length() >= first_expression);
   return length() == first_expression;
 }
 
 
 void HEnvironment::SetExpressionStackAt(int index_from_top, HValue* value) {
   int count = index_from_top + 1;
   int index = values_.length() - count;
   ASSERT(HasExpressionAt(index));
   // The push count must include at least the element in question or else
@@ skipping 58 matching lines @@
       inner->SetValueAt(i, push);
     }
   } else {
     ASSERT(compilation_phase == LITHIUM);
     for (int i = 0; i <= arity; ++i) {  // Include receiver.
       HValue* push = ExpressionStackAt(arity - i);
       inner->SetValueAt(i, push);
     }
   }
 
-  // Initialize the stack-allocated locals to undefined.
+  // Initialize the stack-allocated locals and specials to undefined.
   int local_base = arity + 1;
-  int local_count = function->scope()->num_stack_slots();
-  for (int i = 0; i < local_count; ++i) {
+  int local_count = function->scope()->num_stack_slots() + specials_count();

[Kevin Millikin (Chromium), 2011/05/06 12:29:45]

Don't call these local_base and local_count since they include more than the
locals.  Use 'base' and 'count', or else write:

inner->BindContext(outer->LookupContext());
int local_base = arity + 2;
int local_count = function->scope()->num_stack_slots();
// Loop from 0 to local_count.

+
+
+  //  HContext* inner_context = new(zone) HContext;

[Kevin Millikin (Chromium), 2011/05/06 12:29:45]

Remove me.

+  // This HContext will be added to the graph by the caller of this function.

[Kevin Millikin (Chromium), 2011/05/06 12:29:45]

Comment is probably unnecessary, we don't say this anywhere else that we have
HEnvironment::Lookup or HEnvironment::LookupContext.

+  inner->SetValueAt(local_base, outer->LookupContext());
+  for (int i = 1; i < local_count; ++i) {
     inner->SetValueAt(local_base + i, undefined);
   }
 
   inner->set_ast_id(AstNode::kFunctionEntryId);
   return inner;
 }
 
 
 void HEnvironment::PrintTo(StringStream* stream) {
   for (int i = 0; i < length(); i++) {
     if (i == 0) stream->Add("parameters\n");
-    if (i == parameter_count()) stream->Add("locals\n");
-    if (i == parameter_count() + local_count()) stream->Add("expressions");
+    if (i == parameter_count()) stream->Add("specials\n");
+    if (i == parameter_count() + specials_count()) stream->Add("locals\n");
+    if (i == parameter_count() + specials_count() + local_count()) {
+      stream->Add("expressions");
+    }
     HValue* val = values_.at(i);
     stream->Add("%d: ", i);
     if (val != NULL) {
       val->PrintNameTo(stream);
     } else {
       stream->Add("NULL");
     }
     stream->Add("\n");
   }
 }
@@ skipping 305 matching lines @@
     }
   }
 
 #ifdef DEBUG
   if (graph_ != NULL) graph_->Verify();
   if (allocator_ != NULL) allocator_->Verify();
 #endif
 }
 
 } }  // namespace v8::internal