Cleanup of contexts in the full code generator.

src/ia32/full-codegen-ia32.cc

 // Copyright 2010 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 221 matching lines @@
   } else if (right->IsSmiLiteral()) {
     return kRightConstant;
   } else if (left->IsSmiLiteral() && !Token::IsShiftOp(op)) {
     return kLeftConstant;
   } else {
     return kNoConstants;
   }
 }
 
 
-void FullCodeGenerator::Apply(Expression::Context context, Register reg) {
-  switch (context) {
-    case Expression::kUninitialized:
-      UNREACHABLE();
+void FullCodeGenerator::EffectContext::Plug(Slot* slot) const {
+  // Nothing to do.
+}
 
-    case Expression::kEffect:
-      // Nothing to do.
-      break;
 
-    case Expression::kValue:
-      // Move value into place.
-      switch (location_) {
-        case kAccumulator:
-          if (!reg.is(result_register())) __ mov(result_register(), reg);
-          break;
-        case kStack:
-          __ push(reg);
-          break;
-      }
-      break;
+void FullCodeGenerator::AccumulatorValueContext::Plug(Slot* slot) const {
+  MemOperand slot_operand = codegen()->EmitSlotSearch(slot, result_register());
+  __ mov(result_register(), slot_operand);
+}
 
-    case Expression::kTest:
-      // For simplicity we always test the accumulator register.
-      if (!reg.is(result_register())) __ mov(result_register(), reg);
-      DoTest(true_label_, false_label_, fall_through_);
-      break;
+
+void FullCodeGenerator::StackValueContext::Plug(Slot* slot) const {
+  MemOperand slot_operand = codegen()->EmitSlotSearch(slot, result_register());
+  // Memory operands can be pushed directly.
+  __ push(slot_operand);
+}
+
+
+void FullCodeGenerator::TestContext::Plug(Slot* slot) const {
+  // For simplicity we always test the accumulator register.
+  codegen()->Move(result_register(), slot);
+  codegen()->DoTest(true_label_, false_label_, fall_through_);
+}
+
+
+void FullCodeGenerator::EffectContext::Plug(Heap::RootListIndex index) const {
+  UNREACHABLE();  // Not used on IA32.
+}
+
+
+void FullCodeGenerator::AccumulatorValueContext::Plug(
+    Heap::RootListIndex index) const {
+  UNREACHABLE();  // Not used on IA32.
+}
+
+
+void FullCodeGenerator::StackValueContext::Plug(
+    Heap::RootListIndex index) const {
+  UNREACHABLE();  // Not used on IA32.
+}
+
+
+void FullCodeGenerator::TestContext::Plug(Heap::RootListIndex index) const {
+  UNREACHABLE();  // Not used on IA32.
+}
+
+
+void FullCodeGenerator::EffectContext::Plug(Handle<Object> lit) const {
+  // Nothing to do.
+}
+
+
+void FullCodeGenerator::AccumulatorValueContext::Plug(
+    Handle<Object> lit) const {
+  __ mov(result_register(), lit);
+}
+
+
+void FullCodeGenerator::StackValueContext::Plug(Handle<Object> lit) const {
+  // Immediates can be pushed directly.
+  __ push(Immediate(lit));
+}
+
+
+void FullCodeGenerator::TestContext::Plug(Handle<Object> lit) const {
+  ASSERT(!lit->IsUndetectableObject());  // There are no undetectable literals.
+  if (lit->IsUndefined() || lit->IsNull() || lit->IsFalse()) {
+    __ jmp(false_label_);
+  } else if (lit->IsTrue() || lit->IsJSObject()) {
+    __ jmp(true_label_);
+  } else if (lit->IsString()) {
+    if (String::cast(*lit)->length() == 0) {
+      __ jmp(false_label_);
+    } else {
+      __ jmp(true_label_);
+    }
+  } else if (lit->IsSmi()) {
+    if (Smi::cast(*lit)->value() == 0) {
+      __ jmp(false_label_);
+    } else {
+      __ jmp(true_label_);
+    }
+  } else {
+    // For simplicity we always test the accumulator register.
+    __ mov(result_register(), lit);
+    codegen()->DoTest(true_label_, false_label_, fall_through_);
   }
 }
 
 
-void FullCodeGenerator::Apply(Expression::Context context, Slot* slot) {
-  switch (context) {
-    case Expression::kUninitialized:
-      UNREACHABLE();
-    case Expression::kEffect:
-      // Nothing to do.
-      break;
-    case Expression::kValue: {
-      MemOperand slot_operand = EmitSlotSearch(slot, result_register());
-      switch (location_) {
-        case kAccumulator:
-          __ mov(result_register(), slot_operand);
-          break;
-        case kStack:
-          // Memory operands can be pushed directly.
-          __ push(slot_operand);
-          break;
-      }
-      break;
-    }
+void FullCodeGenerator::StackValueContext::DropAndPlug(int count,
+                                                       Register reg) const {
+  ASSERT(count > 0);
+  if (count > 1) __ Drop(count - 1);
+  __ mov(Operand(esp, 0), reg);
+}
 
-    case Expression::kTest:
-      // For simplicity we always test the accumulator register.
-      Move(result_register(), slot);
-      DoTest(true_label_, false_label_, fall_through_);
-      break;
+
+void FullCodeGenerator::EffectContext::Plug(Label* materialize_true,
+                                            Label* materialize_false) const {
+  ASSERT_EQ(materialize_true, materialize_false);
+  __ bind(materialize_true);
+}
+
+
+void FullCodeGenerator::AccumulatorValueContext::Plug(
+    Label* materialize_true,
+    Label* materialize_false) const {
+  Label done;
+  __ bind(materialize_true);
+  __ mov(result_register(), Factory::true_value());
+  __ jmp(&done);
+  __ bind(materialize_false);
+  __ mov(result_register(), Factory::false_value());
+  __ bind(&done);
+}
+
+
+void FullCodeGenerator::StackValueContext::Plug(
+    Label* materialize_true,
+    Label* materialize_false) const {
+  Label done;
+  __ bind(materialize_true);
+  __ push(Immediate(Factory::true_value()));
+  __ jmp(&done);
+  __ bind(materialize_false);
+  __ push(Immediate(Factory::false_value()));
+  __ bind(&done);
+}
+
+
+void FullCodeGenerator::TestContext::Plug(Label* materialize_true,
+                                          Label* materialize_false) const {
+}
+
+
+void FullCodeGenerator::EffectContext::Plug(bool flag) const {
+}
+
+
+void FullCodeGenerator::AccumulatorValueContext::Plug(bool flag) const {
+  Handle<Object> value =
+      flag ? Factory::true_value() : Factory::false_value();
+  __ mov(result_register(), value);
+}
+
+
+void FullCodeGenerator::StackValueContext::Plug(bool flag) const {
+  Handle<Object> value =
+      flag ? Factory::true_value() : Factory::false_value();
+  __ push(Immediate(value));
+}
+
+
+void FullCodeGenerator::TestContext::Plug(bool flag) const {
+  if (flag) {
+    if (true_label_ != fall_through_) __ jmp(true_label_);
+  } else {
+    if (false_label_ != fall_through_) __ jmp(false_label_);
   }
 }
 
-
-void FullCodeGenerator::Apply(Expression::Context context, Literal* lit) {
-  switch (context) {
-    case Expression::kUninitialized:
-      UNREACHABLE();
-    case Expression::kEffect:
-      // Nothing to do.
-      break;
-    case Expression::kValue:
-      switch (location_) {
-        case kAccumulator:
-          __ mov(result_register(), lit->handle());
-          break;
-        case kStack:
-          // Immediates can be pushed directly.
-          __ push(Immediate(lit->handle()));
-          break;
-      }
-      break;
-
-    case Expression::kTest:
-      // For simplicity we always test the accumulator register.
-      __ mov(result_register(), lit->handle());
-      DoTest(true_label_, false_label_, fall_through_);
-      break;
-  }
-}
-
-
-void FullCodeGenerator::ApplyTOS(Expression::Context context) {
-  switch (context) {
-    case Expression::kUninitialized:
-      UNREACHABLE();
-
-    case Expression::kEffect:
-      __ Drop(1);
-      break;
-
-    case Expression::kValue:
-      switch (location_) {
-        case kAccumulator:
-          __ pop(result_register());
-          break;
-        case kStack:
-          break;
-      }
-      break;
-
-    case Expression::kTest:
-      // For simplicity we always test the accumulator register.
-      __ pop(result_register());
-      DoTest(true_label_, false_label_, fall_through_);
-      break;
-  }
-}
-
-
-void FullCodeGenerator::DropAndApply(int count,
-                                     Expression::Context context,
-                                     Register reg) {
-  ASSERT(count > 0);
-  ASSERT(!reg.is(esp));
-  switch (context) {
-    case Expression::kUninitialized:
-      UNREACHABLE();
-
-    case Expression::kEffect:
-      __ Drop(count);
-      break;
-
-    case Expression::kValue:
-      switch (location_) {
-        case kAccumulator:
-          __ Drop(count);
-          if (!reg.is(result_register())) __ mov(result_register(), reg);
-          break;
-        case kStack:
-          if (count > 1) __ Drop(count - 1);
-          __ mov(Operand(esp, 0), reg);
-          break;
-      }
-      break;
-
-    case Expression::kTest:
-      // For simplicity we always test the accumulator register.
-      __ Drop(count);
-      if (!reg.is(result_register())) __ mov(result_register(), reg);
-      DoTest(true_label_, false_label_, fall_through_);
-      break;
-  }
-}
-
-
-void FullCodeGenerator::Apply(Expression::Context context,
-                              Label* materialize_true,
-                              Label* materialize_false) {
-  switch (context) {
-    case Expression::kUninitialized:
-
-    case Expression::kEffect:
-      ASSERT_EQ(materialize_true, materialize_false);
-      __ bind(materialize_true);
-      break;
-
-    case Expression::kValue: {
-      Label done;
-      switch (location_) {
-        case kAccumulator:
-          __ bind(materialize_true);
-          __ mov(result_register(), Factory::true_value());
-          __ jmp(&done);
-          __ bind(materialize_false);
-          __ mov(result_register(), Factory::false_value());
-          break;
-        case kStack:
-          __ bind(materialize_true);
-          __ push(Immediate(Factory::true_value()));
-          __ jmp(&done);
-          __ bind(materialize_false);
-          __ push(Immediate(Factory::false_value()));
-          break;
-      }
-      __ bind(&done);
-      break;
-    }
-
-    case Expression::kTest:
-      break;
-  }
-}
-
-
-// Convert constant control flow (true or false) to the result expected for
-// a given expression context.
-void FullCodeGenerator::Apply(Expression::Context context, bool flag) {
-  switch (context) {
-    case Expression::kUninitialized:
-      UNREACHABLE();
-      break;
-    case Expression::kEffect:
-      break;
-    case Expression::kValue: {
-      Handle<Object> value =
-          flag ? Factory::true_value() : Factory::false_value();
-      switch (location_) {
-        case kAccumulator:
-          __ mov(result_register(), value);
-          break;
-        case kStack:
-          __ push(Immediate(value));
-          break;
-      }
-      break;
-    }
-    case Expression::kTest:
-      if (flag) {
-        if (true_label_ != fall_through_) __ jmp(true_label_);
-      } else {
-        if (false_label_ != fall_through_) __ jmp(false_label_);
-      }
-      break;
-  }
-}
-
 
 void FullCodeGenerator::DoTest(Label* if_true,
                                Label* if_false,
                                Label* fall_through) {
   // Emit the inlined tests assumed by the stub.
   __ cmp(result_register(), Factory::undefined_value());
   __ j(equal, if_false);
   __ cmp(result_register(), Factory::true_value());
   __ j(equal, if_true);
   __ cmp(result_register(), Factory::false_value());
@@ skipping 79 matching lines @@
   Slot* slot = variable->slot();
   Property* prop = variable->AsProperty();
   if (slot != NULL) {
     switch (slot->type()) {
       case Slot::PARAMETER:
       case Slot::LOCAL:
         if (mode == Variable::CONST) {
           __ mov(Operand(ebp, SlotOffset(slot)),
                  Immediate(Factory::the_hole_value()));
         } else if (function != NULL) {
-          VisitForValue(function, kAccumulator);
+          VisitForAccumulatorValue(function);
           __ mov(Operand(ebp, SlotOffset(slot)), result_register());
         }
         break;
 
       case Slot::CONTEXT:
         // We bypass the general EmitSlotSearch because we know more about
         // this specific context.
 
         // The variable in the decl always resides in the current context.
         ASSERT_EQ(0, scope()->ContextChainLength(variable->scope()));
         if (FLAG_debug_code) {
           // Check if we have the correct context pointer.
           __ mov(ebx, ContextOperand(esi, Context::FCONTEXT_INDEX));
           __ cmp(ebx, Operand(esi));
           __ Check(equal, "Unexpected declaration in current context.");
         }
         if (mode == Variable::CONST) {
           __ mov(ContextOperand(esi, slot->index()),
                  Immediate(Factory::the_hole_value()));
           // No write barrier since the hole value is in old space.
         } else if (function != NULL) {
-          VisitForValue(function, kAccumulator);
+          VisitForAccumulatorValue(function);
           __ mov(ContextOperand(esi, slot->index()), result_register());
           int offset = Context::SlotOffset(slot->index());
           __ mov(ebx, esi);
           __ RecordWrite(ebx, offset, result_register(), ecx);
         }
         break;
 
       case Slot::LOOKUP: {
         __ push(esi);
         __ push(Immediate(variable->name()));
         // Declaration nodes are always introduced in one of two modes.
         ASSERT(mode == Variable::VAR || mode == Variable::CONST);
         PropertyAttributes attr = (mode == Variable::VAR) ? NONE : READ_ONLY;
         __ push(Immediate(Smi::FromInt(attr)));
         // Push initial value, if any.
         // Note: For variables we must not push an initial value (such as
         // 'undefined') because we may have a (legal) redeclaration and we
         // must not destroy the current value.
         if (mode == Variable::CONST) {
           __ push(Immediate(Factory::the_hole_value()));
         } else if (function != NULL) {
-          VisitForValue(function, kStack);
+          VisitForStackValue(function);
         } else {
           __ push(Immediate(Smi::FromInt(0)));  // No initial value!
         }
         __ CallRuntime(Runtime::kDeclareContextSlot, 4);
         break;
       }
     }
 
   } else if (prop != NULL) {
     if (function != NULL || mode == Variable::CONST) {
       // We are declaring a function or constant that rewrites to a
       // property.  Use (keyed) IC to set the initial value.
-      VisitForValue(prop->obj(), kStack);
+      VisitForStackValue(prop->obj());
       if (function != NULL) {
-        VisitForValue(prop->key(), kStack);
-        VisitForValue(function, kAccumulator);
+        VisitForStackValue(prop->key());
+        VisitForAccumulatorValue(function);
         __ pop(ecx);
       } else {
-        VisitForValue(prop->key(), kAccumulator);
+        VisitForAccumulatorValue(prop->key());
         __ mov(ecx, result_register());
         __ mov(result_register(), Factory::the_hole_value());
       }
       __ pop(edx);
 
       Handle<Code> ic(Builtins::builtin(Builtins::KeyedStoreIC_Initialize));
       __ call(ic, RelocInfo::CODE_TARGET);
       // Absence of a test eax instruction following the call
       // indicates that none of the load was inlined.
       __ nop();
@@ skipping 15 matching lines @@
   __ CallRuntime(Runtime::kDeclareGlobals, 3);
   // Return value is ignored.
 }
 
 
 void FullCodeGenerator::VisitSwitchStatement(SwitchStatement* stmt) {
   Comment cmnt(masm_, "[ SwitchStatement");
   Breakable nested_statement(this, stmt);
   SetStatementPosition(stmt);
   // Keep the switch value on the stack until a case matches.
-  VisitForValue(stmt->tag(), kStack);
+  VisitForStackValue(stmt->tag());
 
   ZoneList<CaseClause*>* clauses = stmt->cases();
   CaseClause* default_clause = NULL;  // Can occur anywhere in the list.
 
   Label next_test;  // Recycled for each test.
   // Compile all the tests with branches to their bodies.
   for (int i = 0; i < clauses->length(); i++) {
     CaseClause* clause = clauses->at(i);
     // The default is not a test, but remember it as final fall through.
     if (clause->is_default()) {
       default_clause = clause;
       continue;
     }
 
     Comment cmnt(masm_, "[ Case comparison");
     __ bind(&next_test);
     next_test.Unuse();
 
     // Compile the label expression.
-    VisitForValue(clause->label(), kAccumulator);
+    VisitForAccumulatorValue(clause->label());
 
     // Perform the comparison as if via '==='.
     __ mov(edx, Operand(esp, 0));  // Switch value.
     if (ShouldInlineSmiCase(Token::EQ_STRICT)) {
       Label slow_case;
       __ mov(ecx, edx);
       __ or_(ecx, Operand(eax));
       __ test(ecx, Immediate(kSmiTagMask));
       __ j(not_zero, &slow_case, not_taken);
       __ cmp(edx, Operand(eax));
@@ skipping 37 matching lines @@
   Comment cmnt(masm_, "[ ForInStatement");
   SetStatementPosition(stmt);
 
   Label loop, exit;
   ForIn loop_statement(this, stmt);
   increment_loop_depth();
 
   // Get the object to enumerate over. Both SpiderMonkey and JSC
   // ignore null and undefined in contrast to the specification; see
   // ECMA-262 section 12.6.4.
-  VisitForValue(stmt->enumerable(), kAccumulator);
+  VisitForAccumulatorValue(stmt->enumerable());
   __ cmp(eax, Factory::undefined_value());
   __ j(equal, &exit);
   __ cmp(eax, Factory::null_value());
   __ j(equal, &exit);
 
   // Convert the object to a JS object.
   Label convert, done_convert;
   __ test(eax, Immediate(kSmiTagMask));
   __ j(zero, &convert);
   __ CmpObjectType(eax, FIRST_JS_OBJECT_TYPE, ecx);
@@ skipping 159 matching lines @@
   // space for nested functions that don't need literals cloning.
   if (scope()->is_function_scope() && info->num_literals() == 0) {
     FastNewClosureStub stub;
     __ push(Immediate(info));
     __ CallStub(&stub);
   } else {
     __ push(esi);
     __ push(Immediate(info));
     __ CallRuntime(Runtime::kNewClosure, 2);
   }
-  Apply(context_, eax);
+  context()->Plug(eax);
 }
 
 
 void FullCodeGenerator::VisitVariableProxy(VariableProxy* expr) {
   Comment cmnt(masm_, "[ VariableProxy");
-  EmitVariableLoad(expr->var(), context_);
+  EmitVariableLoad(expr->var());
 }
 
 
 void FullCodeGenerator::EmitLoadGlobalSlotCheckExtensions(
     Slot* slot,
     TypeofState typeof_state,
     Label* slow) {
   Register context = esi;
   Register temp = edx;
 
@@ skipping 128 matching lines @@
           Handle<Code> ic(Builtins::builtin(Builtins::KeyedLoadIC_Initialize));
           __ call(ic, RelocInfo::CODE_TARGET);
           __ jmp(done);
         }
       }
     }
   }
 }
 
 
-void FullCodeGenerator::EmitVariableLoad(Variable* var,
-                                         Expression::Context context) {
+void FullCodeGenerator::EmitVariableLoad(Variable* var) {
   // Four cases: non-this global variables, lookup slots, all other
   // types of slots, and parameters that rewrite to explicit property
   // accesses on the arguments object.
   Slot* slot = var->slot();
   Property* property = var->AsProperty();
 
   if (var->is_global() && !var->is_this()) {
     Comment cmnt(masm_, "Global variable");
     // Use inline caching. Variable name is passed in ecx and the global
     // object on the stack.
     __ mov(eax, CodeGenerator::GlobalObject());
     __ mov(ecx, var->name());
     Handle<Code> ic(Builtins::builtin(Builtins::LoadIC_Initialize));
     __ call(ic, RelocInfo::CODE_TARGET_CONTEXT);
     // By emitting a nop we make sure that we do not have a test eax
     // instruction after the call it is treated specially by the LoadIC code
     // Remember that the assembler may choose to do peephole optimization
     // (eg, push/pop elimination).
     __ nop();
-    Apply(context, eax);
+    context()->Plug(eax);
 
   } else if (slot != NULL && slot->type() == Slot::LOOKUP) {
     Label done, slow;
 
     // Generate code for loading from variables potentially shadowed
     // by eval-introduced variables.
     EmitDynamicLoadFromSlotFastCase(slot, NOT_INSIDE_TYPEOF, &slow, &done);
 
     __ bind(&slow);
     Comment cmnt(masm_, "Lookup slot");
     __ push(esi);  // Context.
     __ push(Immediate(var->name()));
     __ CallRuntime(Runtime::kLoadContextSlot, 2);
     __ bind(&done);
 
-    Apply(context, eax);
+    context()->Plug(eax);
 
   } else if (slot != NULL) {
     Comment cmnt(masm_, (slot->type() == Slot::CONTEXT)
                             ? "Context slot"
                             : "Stack slot");
     if (var->mode() == Variable::CONST) {
       // Constants may be the hole value if they have not been initialized.
       // Unhole them.
       Label done;
       MemOperand slot_operand = EmitSlotSearch(slot, eax);
       __ mov(eax, slot_operand);
       __ cmp(eax, Factory::the_hole_value());
       __ j(not_equal, &done);
       __ mov(eax, Factory::undefined_value());
       __ bind(&done);
-      Apply(context, eax);
+      context()->Plug(eax);
     } else {
-      Apply(context, slot);
+      context()->Plug(slot);
     }
 
   } else {
     Comment cmnt(masm_, "Rewritten parameter");
     ASSERT_NOT_NULL(property);
     // Rewritten parameter accesses are of the form "slot[literal]".
 
     // Assert that the object is in a slot.
     Variable* object_var = property->obj()->AsVariableProxy()->AsVariable();
     ASSERT_NOT_NULL(object_var);
@@ skipping 12 matching lines @@
     // Load the key.
     __ mov(eax, Immediate(key_literal->handle()));
 
     // Do a keyed property load.
     Handle<Code> ic(Builtins::builtin(Builtins::KeyedLoadIC_Initialize));
     __ call(ic, RelocInfo::CODE_TARGET);
     // Notice: We must not have a "test eax, ..." instruction after the
     // call. It is treated specially by the LoadIC code.
     __ nop();
     // Drop key and object left on the stack by IC.
-    Apply(context, eax);
+    context()->Plug(eax);
   }
 }
 
 
 void FullCodeGenerator::VisitRegExpLiteral(RegExpLiteral* expr) {
   Comment cmnt(masm_, "[ RegExpLiteral");
   Label materialized;
   // Registers will be used as follows:
   // edi = JS function.
   // ecx = literals array.
@@ skipping 34 matching lines @@
   for (int i = 0; i < size - kPointerSize; i += 2 * kPointerSize) {
     __ mov(edx, FieldOperand(ebx, i));
     __ mov(ecx, FieldOperand(ebx, i + kPointerSize));
     __ mov(FieldOperand(eax, i), edx);
     __ mov(FieldOperand(eax, i + kPointerSize), ecx);
   }
   if ((size % (2 * kPointerSize)) != 0) {
     __ mov(edx, FieldOperand(ebx, size - kPointerSize));
     __ mov(FieldOperand(eax, size - kPointerSize), edx);
   }
-  Apply(context_, eax);
+  context()->Plug(eax);
 }
 
 
 void FullCodeGenerator::VisitObjectLiteral(ObjectLiteral* expr) {
   Comment cmnt(masm_, "[ ObjectLiteral");
   __ mov(edi, Operand(ebp, JavaScriptFrameConstants::kFunctionOffset));
   __ push(FieldOperand(edi, JSFunction::kLiteralsOffset));
   __ push(Immediate(Smi::FromInt(expr->literal_index())));
   __ push(Immediate(expr->constant_properties()));
   __ push(Immediate(Smi::FromInt(expr->fast_elements() ? 1 : 0)));
@@ skipping 16 matching lines @@
     if (!result_saved) {
       __ push(eax);  // Save result on the stack
       result_saved = true;
     }
     switch (property->kind()) {
       case ObjectLiteral::Property::MATERIALIZED_LITERAL:
         ASSERT(!CompileTimeValue::IsCompileTimeValue(value));
         // Fall through.
       case ObjectLiteral::Property::COMPUTED:
         if (key->handle()->IsSymbol()) {
-          VisitForValue(value, kAccumulator);
+          VisitForAccumulatorValue(value);
           __ mov(ecx, Immediate(key->handle()));
           __ mov(edx, Operand(esp, 0));
           Handle<Code> ic(Builtins::builtin(Builtins::StoreIC_Initialize));
           __ call(ic, RelocInfo::CODE_TARGET);
           __ nop();
           break;
         }
         // Fall through.
       case ObjectLiteral::Property::PROTOTYPE:
         __ push(Operand(esp, 0));  // Duplicate receiver.
-        VisitForValue(key, kStack);
-        VisitForValue(value, kStack);
+        VisitForStackValue(key);
+        VisitForStackValue(value);
         __ CallRuntime(Runtime::kSetProperty, 3);
         break;
       case ObjectLiteral::Property::SETTER:
       case ObjectLiteral::Property::GETTER:
         __ push(Operand(esp, 0));  // Duplicate receiver.
-        VisitForValue(key, kStack);
+        VisitForStackValue(key);
         __ push(Immediate(property->kind() == ObjectLiteral::Property::SETTER ?
                           Smi::FromInt(1) :
                           Smi::FromInt(0)));
-        VisitForValue(value, kStack);
+        VisitForStackValue(value);
         __ CallRuntime(Runtime::kDefineAccessor, 4);
         break;
       default: UNREACHABLE();
     }
   }
 
   if (result_saved) {
-    ApplyTOS(context_);
+    context()->PlugTOS();
   } else {
-    Apply(context_, eax);
+    context()->Plug(eax);
   }
 }
 
 
 void FullCodeGenerator::VisitArrayLiteral(ArrayLiteral* expr) {
   Comment cmnt(masm_, "[ ArrayLiteral");
 
   ZoneList<Expression*>* subexprs = expr->values();
   int length = subexprs->length();
 
@@ skipping 26 matching lines @@
     // is already set in the cloned array.
     if (subexpr->AsLiteral() != NULL ||
         CompileTimeValue::IsCompileTimeValue(subexpr)) {
       continue;
     }
 
     if (!result_saved) {
       __ push(eax);
       result_saved = true;
     }
-    VisitForValue(subexpr, kAccumulator);
+    VisitForAccumulatorValue(subexpr);
 
     // Store the subexpression value in the array's elements.
     __ mov(ebx, Operand(esp, 0));  // Copy of array literal.
     __ mov(ebx, FieldOperand(ebx, JSObject::kElementsOffset));
     int offset = FixedArray::kHeaderSize + (i * kPointerSize);
     __ mov(FieldOperand(ebx, offset), result_register());
 
     // Update the write barrier for the array store.
     __ RecordWrite(ebx, offset, result_register(), ecx);
   }
 
   if (result_saved) {
-    ApplyTOS(context_);
+    context()->PlugTOS();
   } else {
-    Apply(context_, eax);
+    context()->Plug(eax);
   }
 }
 
 
 void FullCodeGenerator::VisitAssignment(Assignment* expr) {
   Comment cmnt(masm_, "[ Assignment");
   // Invalid left-hand sides are rewritten to have a 'throw ReferenceError'
   // on the left-hand side.
   if (!expr->target()->IsValidLeftHandSide()) {
     VisitForEffect(expr->target());
@@ skipping 12 matching lines @@
   }
 
   // Evaluate LHS expression.
   switch (assign_type) {
     case VARIABLE:
       // Nothing to do here.
       break;
     case NAMED_PROPERTY:
       if (expr->is_compound()) {
         // We need the receiver both on the stack and in the accumulator.
-        VisitForValue(property->obj(), kAccumulator);
+        VisitForAccumulatorValue(property->obj());
         __ push(result_register());
       } else {
-        VisitForValue(property->obj(), kStack);
+        VisitForStackValue(property->obj());
       }
       break;
     case KEYED_PROPERTY:
       if (expr->is_compound()) {
-        VisitForValue(property->obj(), kStack);
-        VisitForValue(property->key(), kAccumulator);
+        VisitForStackValue(property->obj());
+        VisitForAccumulatorValue(property->key());
         __ mov(edx, Operand(esp, 0));
         __ push(eax);
       } else {
-        VisitForValue(property->obj(), kStack);
-        VisitForValue(property->key(), kStack);
+        VisitForStackValue(property->obj());
+        VisitForStackValue(property->key());
       }
       break;
   }
 
   if (expr->is_compound()) {
-    Location saved_location = location_;
-    location_ = kAccumulator;
-    switch (assign_type) {
-      case VARIABLE:
-        EmitVariableLoad(expr->target()->AsVariableProxy()->var(),
-                         Expression::kValue);
-        break;
-      case NAMED_PROPERTY:
-        EmitNamedPropertyLoad(property);
-        break;
-      case KEYED_PROPERTY:
-        EmitKeyedPropertyLoad(property);
-        break;
+    { AccumulatorValueContext context(this);
+      switch (assign_type) {
+        case VARIABLE:
+          EmitVariableLoad(expr->target()->AsVariableProxy()->var());
+          break;
+        case NAMED_PROPERTY:
+          EmitNamedPropertyLoad(property);
+          break;
+        case KEYED_PROPERTY:
+          EmitKeyedPropertyLoad(property);
+          break;
+      }
     }
 
     Token::Value op = expr->binary_op();
     ConstantOperand constant = ShouldInlineSmiCase(op)
         ? GetConstantOperand(op, expr->target(), expr->value())
         : kNoConstants;
     ASSERT(constant == kRightConstant || constant == kNoConstants);
     if (constant == kNoConstants) {
       __ push(eax);  // Left operand goes on the stack.
-      VisitForValue(expr->value(), kAccumulator);
+      VisitForAccumulatorValue(expr->value());
     }
 
     OverwriteMode mode = expr->value()->ResultOverwriteAllowed()
         ? OVERWRITE_RIGHT
         : NO_OVERWRITE;
     SetSourcePosition(expr->position() + 1);
+    AccumulatorValueContext context(this);
     if (ShouldInlineSmiCase(op)) {
       EmitInlineSmiBinaryOp(expr,
                             op,
-                            Expression::kValue,
                             mode,
                             expr->target(),
                             expr->value(),
                             constant);
     } else {
-      EmitBinaryOp(op, Expression::kValue, mode);
+      EmitBinaryOp(op, mode);
     }
-    location_ = saved_location;
-
   } else {
-    VisitForValue(expr->value(), kAccumulator);
+    VisitForAccumulatorValue(expr->value());
   }
 
   // Record source position before possible IC call.
   SetSourcePosition(expr->position());
 
   // Store the value.
   switch (assign_type) {
     case VARIABLE:
       EmitVariableAssignment(expr->target()->AsVariableProxy()->var(),
-                             expr->op(),
-                             context_);
+                             expr->op());
       break;
     case NAMED_PROPERTY:
       EmitNamedPropertyAssignment(expr);
       break;
     case KEYED_PROPERTY:
       EmitKeyedPropertyAssignment(expr);
       break;
   }
 }
 
@@ skipping 10 matching lines @@
 
 void FullCodeGenerator::EmitKeyedPropertyLoad(Property* prop) {
   SetSourcePosition(prop->position());
   Handle<Code> ic(Builtins::builtin(Builtins::KeyedLoadIC_Initialize));
   __ call(ic, RelocInfo::CODE_TARGET);
   __ nop();
 }
 
 
 void FullCodeGenerator::EmitConstantSmiAdd(Expression* expr,
-                                           Expression::Context context,
                                            OverwriteMode mode,
                                            bool left_is_constant_smi,
                                            Smi* value) {
   Label call_stub, done;
   __ add(Operand(eax), Immediate(value));
   __ j(overflow, &call_stub);
   __ test(eax, Immediate(kSmiTagMask));
   __ j(zero, &done);
 
   // Undo the optimistic add operation and call the shared stub.
   __ bind(&call_stub);
   __ sub(Operand(eax), Immediate(value));
   Token::Value op = Token::ADD;
   GenericBinaryOpStub stub(op, mode, NO_SMI_CODE_IN_STUB, TypeInfo::Unknown());
   if (left_is_constant_smi) {
     __ push(Immediate(value));
     __ push(eax);
   } else {
     __ push(eax);
     __ push(Immediate(value));
   }
   __ CallStub(&stub);
   __ bind(&done);
-  Apply(context, eax);
+  context()->Plug(eax);
 }
 
 
 void FullCodeGenerator::EmitConstantSmiSub(Expression* expr,
-                                           Expression::Context context,
                                            OverwriteMode mode,
                                            bool left_is_constant_smi,
                                            Smi* value) {
   Label call_stub, done;
   if (left_is_constant_smi) {
     __ mov(ecx, eax);
     __ mov(eax, Immediate(value));
     __ sub(Operand(eax), ecx);
   } else {
     __ sub(Operand(eax), Immediate(value));
@@ skipping 11 matching lines @@
     __ add(Operand(eax), Immediate(value));
 
     __ push(eax);
     __ push(Immediate(value));
   }
 
   Token::Value op = Token::SUB;
   GenericBinaryOpStub stub(op, mode, NO_SMI_CODE_IN_STUB, TypeInfo::Unknown());
   __ CallStub(&stub);
   __ bind(&done);
-  Apply(context, eax);
+  context()->Plug(eax);
 }
 
 
 void FullCodeGenerator::EmitConstantSmiShiftOp(Expression* expr,
                                                Token::Value op,
-                                               Expression::Context context,
                                                OverwriteMode mode,
                                                Smi* value) {
   Label call_stub, smi_case, done;
   int shift_value = value->value() & 0x1f;
 
   __ test(eax, Immediate(kSmiTagMask));
   __ j(zero, &smi_case);
 
   __ bind(&call_stub);
   GenericBinaryOpStub stub(op, mode, NO_SMI_CODE_IN_STUB, TypeInfo::Unknown());
@@ skipping 36 matching lines @@
         __ SmiUntag(eax);
         __ shr(eax, shift_value);
         __ SmiTag(eax);
       }
       break;
     default:
       UNREACHABLE();
   }
 
   __ bind(&done);
-  Apply(context, eax);
+  context()->Plug(eax);
 }
 
 
 void FullCodeGenerator::EmitConstantSmiBitOp(Expression* expr,
                                              Token::Value op,
-                                             Expression::Context context,
                                              OverwriteMode mode,
                                              Smi* value) {
   Label smi_case, done;
   __ test(eax, Immediate(kSmiTagMask));
   __ j(zero, &smi_case);
 
   GenericBinaryOpStub stub(op, mode, NO_SMI_CODE_IN_STUB, TypeInfo::Unknown());
   // The order of the arguments does not matter for bit-ops with a
   // constant operand.
   __ push(Immediate(value));
@@ skipping 10 matching lines @@
       __ xor_(Operand(eax), Immediate(value));
       break;
     case Token::BIT_AND:
       __ and_(Operand(eax), Immediate(value));
       break;
     default:
       UNREACHABLE();
   }
 
   __ bind(&done);
-  Apply(context, eax);
+  context()->Plug(eax);
 }
 
 
 void FullCodeGenerator::EmitConstantSmiBinaryOp(Expression* expr,
                                                 Token::Value op,
-                                                Expression::Context context,
                                                 OverwriteMode mode,
                                                 bool left_is_constant_smi,
                                                 Smi* value) {
   switch (op) {
     case Token::BIT_OR:
     case Token::BIT_XOR:
     case Token::BIT_AND:
-      EmitConstantSmiBitOp(expr, op, context, mode, value);
+      EmitConstantSmiBitOp(expr, op, mode, value);
       break;
     case Token::SHL:
     case Token::SAR:
     case Token::SHR:
       ASSERT(!left_is_constant_smi);
-      EmitConstantSmiShiftOp(expr, op, context, mode, value);
+      EmitConstantSmiShiftOp(expr, op, mode, value);
       break;
     case Token::ADD:
-      EmitConstantSmiAdd(expr, context, mode, left_is_constant_smi, value);
+      EmitConstantSmiAdd(expr, mode, left_is_constant_smi, value);
       break;
     case Token::SUB:
-      EmitConstantSmiSub(expr, context, mode, left_is_constant_smi, value);
+      EmitConstantSmiSub(expr, mode, left_is_constant_smi, value);
       break;
     default:
       UNREACHABLE();
   }
 }
 
 
 void FullCodeGenerator::EmitInlineSmiBinaryOp(Expression* expr,
                                               Token::Value op,
-                                              Expression::Context context,
                                               OverwriteMode mode,
                                               Expression* left,
                                               Expression* right,
                                               ConstantOperand constant) {
   if (constant == kRightConstant) {
     Smi* value =  Smi::cast(*right->AsLiteral()->handle());
-    EmitConstantSmiBinaryOp(expr, op, context, mode, false, value);
+    EmitConstantSmiBinaryOp(expr, op, mode, false, value);
     return;
   } else if (constant == kLeftConstant) {
     Smi* value =  Smi::cast(*left->AsLiteral()->handle());
-    EmitConstantSmiBinaryOp(expr, op, context, mode, true, value);
+    EmitConstantSmiBinaryOp(expr, op, mode, true, value);
     return;
   }
 
   // Do combined smi check of the operands. Left operand is on the
   // stack. Right operand is in eax.
   Label done, stub_call, smi_case;
   __ pop(edx);
   __ mov(ecx, eax);
   __ or_(eax, Operand(edx));
   __ test(eax, Immediate(kSmiTagMask));
@@ skipping 73 matching lines @@
       __ and_(eax, Operand(ecx));
       break;
     case Token::BIT_XOR:
       __ xor_(eax, Operand(ecx));
       break;
     default:
       UNREACHABLE();
   }
 
   __ bind(&done);
-  Apply(context, eax);
+  context()->Plug(eax);
 }
 
 
 void FullCodeGenerator::EmitBinaryOp(Token::Value op,
-                                     Expression::Context context,
                                      OverwriteMode mode) {
   TypeInfo type = TypeInfo::Unknown();
   GenericBinaryOpStub stub(op, mode, NO_GENERIC_BINARY_FLAGS, type);
   if (stub.ArgsInRegistersSupported()) {
     __ pop(edx);
     stub.GenerateCall(masm_, edx, eax);
   } else {
     __ push(result_register());
     __ CallStub(&stub);
   }
-  Apply(context, eax);
+  context()->Plug(eax);
 }
 
 
 void FullCodeGenerator::EmitAssignment(Expression* expr) {
   // Invalid left-hand sides are rewritten to have a 'throw
   // ReferenceError' on the left-hand side.
   if (!expr->IsValidLeftHandSide()) {
     VisitForEffect(expr);
     return;
   }
 
   // Left-hand side can only be a property, a global or a (parameter or local)
   // slot. Variables with rewrite to .arguments are treated as KEYED_PROPERTY.
   enum LhsKind { VARIABLE, NAMED_PROPERTY, KEYED_PROPERTY };
   LhsKind assign_type = VARIABLE;
   Property* prop = expr->AsProperty();
   if (prop != NULL) {
     assign_type = (prop->key()->IsPropertyName())
         ? NAMED_PROPERTY
         : KEYED_PROPERTY;
   }
 
   switch (assign_type) {
     case VARIABLE: {
       Variable* var = expr->AsVariableProxy()->var();
-      EmitVariableAssignment(var, Token::ASSIGN, Expression::kEffect);
+      EffectContext context(this);
+      EmitVariableAssignment(var, Token::ASSIGN);
       break;
     }
     case NAMED_PROPERTY: {
       __ push(eax);  // Preserve value.
-      VisitForValue(prop->obj(), kAccumulator);
+      VisitForAccumulatorValue(prop->obj());
       __ mov(edx, eax);
       __ pop(eax);  // Restore value.
       __ mov(ecx, prop->key()->AsLiteral()->handle());
       Handle<Code> ic(Builtins::builtin(Builtins::StoreIC_Initialize));
       __ call(ic, RelocInfo::CODE_TARGET);
       __ nop();  // Signal no inlined code.
       break;
     }
     case KEYED_PROPERTY: {
       __ push(eax);  // Preserve value.
-      VisitForValue(prop->obj(), kStack);
-      VisitForValue(prop->key(), kAccumulator);
+      VisitForStackValue(prop->obj());
+      VisitForAccumulatorValue(prop->key());
       __ mov(ecx, eax);
       __ pop(edx);
       __ pop(eax);  // Restore value.
       Handle<Code> ic(Builtins::builtin(Builtins::KeyedStoreIC_Initialize));
       __ call(ic, RelocInfo::CODE_TARGET);
       __ nop();  // Signal no inlined code.
       break;
     }
   }
 }
 
 
 void FullCodeGenerator::EmitVariableAssignment(Variable* var,
-                                               Token::Value op,
-                                               Expression::Context context) {
+                                               Token::Value op) {
   // Left-hand sides that rewrite to explicit property accesses do not reach
   // here.
   ASSERT(var != NULL);
   ASSERT(var->is_global() || var->slot() != NULL);
 
   if (var->is_global()) {
     ASSERT(!var->is_this());
     // Assignment to a global variable.  Use inline caching for the
     // assignment.  Right-hand-side value is passed in eax, variable name in
     // ecx, and the global object on the stack.
@@ skipping 49 matching lines @@
           // The runtime will ignore const redeclaration.
           __ CallRuntime(Runtime::kInitializeConstContextSlot, 3);
         } else {
           __ CallRuntime(Runtime::kStoreContextSlot, 3);
         }
         break;
     }
     __ bind(&done);
   }
 
-  Apply(context, eax);
+  context()->Plug(eax);
 }
 
 
 void FullCodeGenerator::EmitNamedPropertyAssignment(Assignment* expr) {
   // Assignment to a property, using a named store IC.
   Property* prop = expr->target()->AsProperty();
   ASSERT(prop != NULL);
   ASSERT(prop->key()->AsLiteral() != NULL);
 
   // If the assignment starts a block of assignments to the same object,
@@ skipping 17 matching lines @@
   Handle<Code> ic(Builtins::builtin(Builtins::StoreIC_Initialize));
   __ call(ic, RelocInfo::CODE_TARGET);
   __ nop();
 
   // If the assignment ends an initialization block, revert to fast case.
   if (expr->ends_initialization_block()) {
     __ push(eax);  // Result of assignment, saved even if not needed.
     __ push(Operand(esp, kPointerSize));  // Receiver is under value.
     __ CallRuntime(Runtime::kToFastProperties, 1);
     __ pop(eax);
-    DropAndApply(1, context_, eax);
+    context()->DropAndPlug(1, eax);
   } else {
-    Apply(context_, eax);
+    context()->Plug(eax);
   }
 }
 
 
 void FullCodeGenerator::EmitKeyedPropertyAssignment(Assignment* expr) {
   // Assignment to a property, using a keyed store IC.
 
   // If the assignment starts a block of assignments to the same object,
   // change to slow case to avoid the quadratic behavior of repeatedly
   // adding fast properties.
@@ skipping 21 matching lines @@
 
   // If the assignment ends an initialization block, revert to fast case.
   if (expr->ends_initialization_block()) {
     __ pop(edx);
     __ push(eax);  // Result of assignment, saved even if not needed.
     __ push(edx);
     __ CallRuntime(Runtime::kToFastProperties, 1);
     __ pop(eax);
   }
 
-  Apply(context_, eax);
+  context()->Plug(eax);
 }
 
 
 void FullCodeGenerator::VisitProperty(Property* expr) {
   Comment cmnt(masm_, "[ Property");
   Expression* key = expr->key();
 
   if (key->IsPropertyName()) {
-    VisitForValue(expr->obj(), kAccumulator);
+    VisitForAccumulatorValue(expr->obj());
     EmitNamedPropertyLoad(expr);
-    Apply(context_, eax);
+    context()->Plug(eax);
   } else {
-    VisitForValue(expr->obj(), kStack);
-    VisitForValue(expr->key(), kAccumulator);
+    VisitForStackValue(expr->obj());
+    VisitForAccumulatorValue(expr->key());
     __ pop(edx);
     EmitKeyedPropertyLoad(expr);
-    Apply(context_, eax);
+    context()->Plug(eax);
   }
 }
 
 
 void FullCodeGenerator::EmitCallWithIC(Call* expr,
                                        Handle<Object> name,
                                        RelocInfo::Mode mode) {
   // Code common for calls using the IC.
   ZoneList<Expression*>* args = expr->arguments();
   int arg_count = args->length();
   for (int i = 0; i < arg_count; i++) {
-    VisitForValue(args->at(i), kStack);
+    VisitForStackValue(args->at(i));
   }
   __ Set(ecx, Immediate(name));
   // Record source position of the IC call.
   SetSourcePosition(expr->position());
   InLoopFlag in_loop = (loop_depth() > 0) ? IN_LOOP : NOT_IN_LOOP;
   Handle<Code> ic = CodeGenerator::ComputeCallInitialize(arg_count, in_loop);
   __ call(ic, mode);
   // Restore context register.
   __ mov(esi, Operand(ebp, StandardFrameConstants::kContextOffset));
-  Apply(context_, eax);
+  context()->Plug(eax);
 }
 
 
 void FullCodeGenerator::EmitKeyedCallWithIC(Call* expr,
                                             Expression* key,
                                             RelocInfo::Mode mode) {
   // Code common for calls using the IC.
   ZoneList<Expression*>* args = expr->arguments();
   int arg_count = args->length();
   for (int i = 0; i < arg_count; i++) {
-    VisitForValue(args->at(i), kStack);
+    VisitForStackValue(args->at(i));
   }
-  VisitForValue(key, kAccumulator);
+  VisitForAccumulatorValue(key);
   __ mov(ecx, eax);
   // Record source position of the IC call.
   SetSourcePosition(expr->position());
   InLoopFlag in_loop = (loop_depth() > 0) ? IN_LOOP : NOT_IN_LOOP;
   Handle<Code> ic = CodeGenerator::ComputeKeyedCallInitialize(
       arg_count, in_loop);
   __ call(ic, mode);
   // Restore context register.
   __ mov(esi, Operand(ebp, StandardFrameConstants::kContextOffset));
-  Apply(context_, eax);
+  context()->Plug(eax);
 }
 
 
 void FullCodeGenerator::EmitCallWithStub(Call* expr) {
   // Code common for calls using the call stub.
   ZoneList<Expression*>* args = expr->arguments();
   int arg_count = args->length();
   for (int i = 0; i < arg_count; i++) {
-    VisitForValue(args->at(i), kStack);
+    VisitForStackValue(args->at(i));
   }
   // Record source position for debugger.
   SetSourcePosition(expr->position());
   InLoopFlag in_loop = (loop_depth() > 0) ? IN_LOOP : NOT_IN_LOOP;
   CallFunctionStub stub(arg_count, in_loop, RECEIVER_MIGHT_BE_VALUE);
   __ CallStub(&stub);
   // Restore context register.
   __ mov(esi, Operand(ebp, StandardFrameConstants::kContextOffset));
-  DropAndApply(1, context_, eax);
+  context()->DropAndPlug(1, eax);
 }
 
 
 void FullCodeGenerator::VisitCall(Call* expr) {
   Comment cmnt(masm_, "[ Call");
   Expression* fun = expr->expression();
   Variable* var = fun->AsVariableProxy()->AsVariable();
 
   if (var != NULL && var->is_possibly_eval()) {
     // In a call to eval, we first call %ResolvePossiblyDirectEval to
     // resolve the function we need to call and the receiver of the
     // call.  Then we call the resolved function using the given
     // arguments.
-    VisitForValue(fun, kStack);
+    VisitForStackValue(fun);
     __ push(Immediate(Factory::undefined_value()));  // Reserved receiver slot.
 
     // Push the arguments.
     ZoneList<Expression*>* args = expr->arguments();
     int arg_count = args->length();
     for (int i = 0; i < arg_count; i++) {
-      VisitForValue(args->at(i), kStack);
+      VisitForStackValue(args->at(i));
     }
 
     // Push copy of the function - found below the arguments.
     __ push(Operand(esp, (arg_count + 1) * kPointerSize));
 
     // Push copy of the first argument or undefined if it doesn't exist.
     if (arg_count > 0) {
       __ push(Operand(esp, arg_count * kPointerSize));
     } else {
       __ push(Immediate(Factory::undefined_value()));
     }
 
     // Push the receiver of the enclosing function and do runtime call.
     __ push(Operand(ebp, (2 + scope()->num_parameters()) * kPointerSize));
     __ CallRuntime(Runtime::kResolvePossiblyDirectEval, 3);
 
     // The runtime call returns a pair of values in eax (function) and
     // edx (receiver). Touch up the stack with the right values.
     __ mov(Operand(esp, (arg_count + 0) * kPointerSize), edx);
     __ mov(Operand(esp, (arg_count + 1) * kPointerSize), eax);
 
     // Record source position for debugger.
     SetSourcePosition(expr->position());
     InLoopFlag in_loop = (loop_depth() > 0) ? IN_LOOP : NOT_IN_LOOP;
     CallFunctionStub stub(arg_count, in_loop, RECEIVER_MIGHT_BE_VALUE);
     __ CallStub(&stub);
     // Restore context register.
     __ mov(esi, Operand(ebp, StandardFrameConstants::kContextOffset));
-    DropAndApply(1, context_, eax);
+    context()->DropAndPlug(1, eax);
   } else if (var != NULL && !var->is_this() && var->is_global()) {
     // Push global object as receiver for the call IC.
     __ push(CodeGenerator::GlobalObject());
     EmitCallWithIC(expr, var->name(), RelocInfo::CODE_TARGET_CONTEXT);
   } else if (var != NULL && var->slot() != NULL &&
              var->slot()->type() == Slot::LOOKUP) {
     // Call to a lookup slot (dynamically introduced variable).
     Label slow, done;
 
     // Generate code for loading from variables potentially shadowed
@@ skipping 27 matching lines @@
       __ bind(&call);
     }
 
     EmitCallWithStub(expr);
   } else if (fun->AsProperty() != NULL) {
     // Call to an object property.
     Property* prop = fun->AsProperty();
     Literal* key = prop->key()->AsLiteral();
     if (key != NULL && key->handle()->IsSymbol()) {
       // Call to a named property, use call IC.
-      VisitForValue(prop->obj(), kStack);
+      VisitForStackValue(prop->obj());
       EmitCallWithIC(expr, key->handle(), RelocInfo::CODE_TARGET);
     } else {
       // Call to a keyed property.
       // For a synthetic property use keyed load IC followed by function call,
       // for a regular property use keyed CallIC.
-      VisitForValue(prop->obj(), kStack);
+      VisitForStackValue(prop->obj());
       if (prop->is_synthetic()) {
-        VisitForValue(prop->key(), kAccumulator);
+        VisitForAccumulatorValue(prop->key());
         // Record source code position for IC call.
         SetSourcePosition(prop->position());
         __ pop(edx);  // We do not need to keep the receiver.
 
         Handle<Code> ic(Builtins::builtin(Builtins::KeyedLoadIC_Initialize));
         __ call(ic, RelocInfo::CODE_TARGET);
         // By emitting a nop we make sure that we do not have a "test eax,..."
         // instruction after the call as it is treated specially
         // by the LoadIC code.
         __ nop();
@@ skipping 10 matching lines @@
   } else {
     // Call to some other expression.  If the expression is an anonymous
     // function literal not called in a loop, mark it as one that should
     // also use the full code generator.
     FunctionLiteral* lit = fun->AsFunctionLiteral();
     if (lit != NULL &&
         lit->name()->Equals(Heap::empty_string()) &&
         loop_depth() == 0) {
       lit->set_try_full_codegen(true);
     }
-    VisitForValue(fun, kStack);
+    VisitForStackValue(fun);
     // Load global receiver object.
     __ mov(ebx, CodeGenerator::GlobalObject());
     __ push(FieldOperand(ebx, GlobalObject::kGlobalReceiverOffset));
     // Emit function call.
     EmitCallWithStub(expr);
   }
 }
 
 
 void FullCodeGenerator::VisitCallNew(CallNew* expr) {
   Comment cmnt(masm_, "[ CallNew");
   // According to ECMA-262, section 11.2.2, page 44, the function
   // expression in new calls must be evaluated before the
   // arguments.
 
   // Push constructor on the stack.  If it's not a function it's used as
   // receiver for CALL_NON_FUNCTION, otherwise the value on the stack is
   // ignored.
-  VisitForValue(expr->expression(), kStack);
+  VisitForStackValue(expr->expression());
 
   // Push the arguments ("left-to-right") on the stack.
   ZoneList<Expression*>* args = expr->arguments();
   int arg_count = args->length();
   for (int i = 0; i < arg_count; i++) {
-    VisitForValue(args->at(i), kStack);
+    VisitForStackValue(args->at(i));
   }
 
   // Call the construct call builtin that handles allocation and
   // constructor invocation.
   SetSourcePosition(expr->position());
 
   // Load function and argument count into edi and eax.
   __ Set(eax, Immediate(arg_count));
   __ mov(edi, Operand(esp, arg_count * kPointerSize));
 
   Handle<Code> construct_builtin(Builtins::builtin(Builtins::JSConstructCall));
   __ call(construct_builtin, RelocInfo::CONSTRUCT_CALL);
-  Apply(context_, eax);
+  context()->Plug(eax);
 }
 
 
 void FullCodeGenerator::EmitIsSmi(ZoneList<Expression*>* args) {
   ASSERT(args->length() == 1);
 
-  VisitForValue(args->at(0), kAccumulator);
+  VisitForAccumulatorValue(args->at(0));
 
   Label materialize_true, materialize_false;
   Label* if_true = NULL;
   Label* if_false = NULL;
   Label* fall_through = NULL;
-  PrepareTest(&materialize_true, &materialize_false,
-              &if_true, &if_false, &fall_through);
+  context()->PrepareTest(&materialize_true, &materialize_false,
+                         &if_true, &if_false, &fall_through);
 
   __ test(eax, Immediate(kSmiTagMask));
   Split(zero, if_true, if_false, fall_through);
 
-  Apply(context_, if_true, if_false);
+  context()->Plug(if_true, if_false);
 }
 
 
 void FullCodeGenerator::EmitIsNonNegativeSmi(ZoneList<Expression*>* args) {
   ASSERT(args->length() == 1);
 
-  VisitForValue(args->at(0), kAccumulator);
+  VisitForAccumulatorValue(args->at(0));
 
   Label materialize_true, materialize_false;
   Label* if_true = NULL;
   Label* if_false = NULL;
   Label* fall_through = NULL;
-  PrepareTest(&materialize_true, &materialize_false,
-              &if_true, &if_false, &fall_through);
+  context()->PrepareTest(&materialize_true, &materialize_false,
+                         &if_true, &if_false, &fall_through);
 
   __ test(eax, Immediate(kSmiTagMask | 0x80000000));
   Split(zero, if_true, if_false, fall_through);
 
-  Apply(context_, if_true, if_false);
+  context()->Plug(if_true, if_false);
 }
 
 
 void FullCodeGenerator::EmitIsObject(ZoneList<Expression*>* args) {
   ASSERT(args->length() == 1);
 
-  VisitForValue(args->at(0), kAccumulator);
+  VisitForAccumulatorValue(args->at(0));
 
   Label materialize_true, materialize_false;
   Label* if_true = NULL;
   Label* if_false = NULL;
   Label* fall_through = NULL;
-  PrepareTest(&materialize_true, &materialize_false,
-              &if_true, &if_false, &fall_through);
+  context()->PrepareTest(&materialize_true, &materialize_false,
+                         &if_true, &if_false, &fall_through);
 
   __ test(eax, Immediate(kSmiTagMask));
   __ j(zero, if_false);
   __ cmp(eax, Factory::null_value());
   __ j(equal, if_true);
   __ mov(ebx, FieldOperand(eax, HeapObject::kMapOffset));
   // Undetectable objects behave like undefined when tested with typeof.
   __ movzx_b(ecx, FieldOperand(ebx, Map::kBitFieldOffset));
   __ test(ecx, Immediate(1 << Map::kIsUndetectable));
   __ j(not_zero, if_false);
   __ movzx_b(ecx, FieldOperand(ebx, Map::kInstanceTypeOffset));
   __ cmp(ecx, FIRST_JS_OBJECT_TYPE);
   __ j(below, if_false);
   __ cmp(ecx, LAST_JS_OBJECT_TYPE);
   Split(below_equal, if_true, if_false, fall_through);
 
-  Apply(context_, if_true, if_false);
+  context()->Plug(if_true, if_false);
 }
 
 
 void FullCodeGenerator::EmitIsSpecObject(ZoneList<Expression*>* args) {
   ASSERT(args->length() == 1);
 
-  VisitForValue(args->at(0), kAccumulator);
+  VisitForAccumulatorValue(args->at(0));
 
   Label materialize_true, materialize_false;
   Label* if_true = NULL;
   Label* if_false = NULL;
   Label* fall_through = NULL;
-  PrepareTest(&materialize_true, &materialize_false,
-              &if_true, &if_false, &fall_through);
+  context()->PrepareTest(&materialize_true, &materialize_false,
+                         &if_true, &if_false, &fall_through);
 
   __ test(eax, Immediate(kSmiTagMask));
   __ j(equal, if_false);
   __ CmpObjectType(eax, FIRST_JS_OBJECT_TYPE, ebx);
   Split(above_equal, if_true, if_false, fall_through);
 
-  Apply(context_, if_true, if_false);
+  context()->Plug(if_true, if_false);
 }
 
 
 void FullCodeGenerator::EmitIsUndetectableObject(ZoneList<Expression*>* args) {
   ASSERT(args->length() == 1);
 
-  VisitForValue(args->at(0), kAccumulator);
+  VisitForAccumulatorValue(args->at(0));
 
   Label materialize_true, materialize_false;
   Label* if_true = NULL;
   Label* if_false = NULL;
   Label* fall_through = NULL;
-  PrepareTest(&materialize_true, &materialize_false,
-              &if_true, &if_false, &fall_through);
+  context()->PrepareTest(&materialize_true, &materialize_false,
+                         &if_true, &if_false, &fall_through);
 
   __ test(eax, Immediate(kSmiTagMask));
   __ j(zero, if_false);
   __ mov(ebx, FieldOperand(eax, HeapObject::kMapOffset));
   __ movzx_b(ebx, FieldOperand(ebx, Map::kBitFieldOffset));
   __ test(ebx, Immediate(1 << Map::kIsUndetectable));
   Split(not_zero, if_true, if_false, fall_through);
 
-  Apply(context_, if_true, if_false);
+  context()->Plug(if_true, if_false);
 }
 
 
 void FullCodeGenerator::EmitIsStringWrapperSafeForDefaultValueOf(
     ZoneList<Expression*>* args) {
   ASSERT(args->length() == 1);
 
-  VisitForValue(args->at(0), kAccumulator);
+  VisitForAccumulatorValue(args->at(0));
 
   Label materialize_true, materialize_false;
   Label* if_true = NULL;
   Label* if_false = NULL;
   Label* fall_through = NULL;
-  PrepareTest(&materialize_true, &materialize_false,
-              &if_true, &if_false, &fall_through);
+  context()->PrepareTest(&materialize_true, &materialize_false,
+                         &if_true, &if_false, &fall_through);
 
   // Just indicate false, as %_IsStringWrapperSafeForDefaultValueOf() is only
   // used in a few functions in runtime.js which should not normally be hit by
   // this compiler.
   __ jmp(if_false);
-  Apply(context_, if_true, if_false);
+  context()->Plug(if_true, if_false);
 }
 
 
 void FullCodeGenerator::EmitIsFunction(ZoneList<Expression*>* args) {
   ASSERT(args->length() == 1);
 
-  VisitForValue(args->at(0), kAccumulator);
+  VisitForAccumulatorValue(args->at(0));
 
   Label materialize_true, materialize_false;
   Label* if_true = NULL;
   Label* if_false = NULL;
   Label* fall_through = NULL;
-  PrepareTest(&materialize_true, &materialize_false,
-              &if_true, &if_false, &fall_through);
+  context()->PrepareTest(&materialize_true, &materialize_false,
+                         &if_true, &if_false, &fall_through);
 
   __ test(eax, Immediate(kSmiTagMask));
   __ j(zero, if_false);
   __ CmpObjectType(eax, JS_FUNCTION_TYPE, ebx);
   Split(equal, if_true, if_false, fall_through);
 
-  Apply(context_, if_true, if_false);
+  context()->Plug(if_true, if_false);
 }
 
 
 void FullCodeGenerator::EmitIsArray(ZoneList<Expression*>* args) {
   ASSERT(args->length() == 1);
 
-  VisitForValue(args->at(0), kAccumulator);
+  VisitForAccumulatorValue(args->at(0));
 
   Label materialize_true, materialize_false;
   Label* if_true = NULL;
   Label* if_false = NULL;
   Label* fall_through = NULL;
-  PrepareTest(&materialize_true, &materialize_false,
-              &if_true, &if_false, &fall_through);
+  context()->PrepareTest(&materialize_true, &materialize_false,
+                         &if_true, &if_false, &fall_through);
 
   __ test(eax, Immediate(kSmiTagMask));
   __ j(equal, if_false);
   __ CmpObjectType(eax, JS_ARRAY_TYPE, ebx);
   Split(equal, if_true, if_false, fall_through);
 
-  Apply(context_, if_true, if_false);
+  context()->Plug(if_true, if_false);
 }
 
 
 void FullCodeGenerator::EmitIsRegExp(ZoneList<Expression*>* args) {
   ASSERT(args->length() == 1);
 
-  VisitForValue(args->at(0), kAccumulator);
+  VisitForAccumulatorValue(args->at(0));
 
   Label materialize_true, materialize_false;
   Label* if_true = NULL;
   Label* if_false = NULL;
   Label* fall_through = NULL;
-  PrepareTest(&materialize_true, &materialize_false,
-              &if_true, &if_false, &fall_through);
+  context()->PrepareTest(&materialize_true, &materialize_false,
+                         &if_true, &if_false, &fall_through);
 
   __ test(eax, Immediate(kSmiTagMask));
   __ j(equal, if_false);
   __ CmpObjectType(eax, JS_REGEXP_TYPE, ebx);
   Split(equal, if_true, if_false, fall_through);
 
-  Apply(context_, if_true, if_false);
+  context()->Plug(if_true, if_false);
 }
 
 
 
 void FullCodeGenerator::EmitIsConstructCall(ZoneList<Expression*>* args) {
   ASSERT(args->length() == 0);
 
   Label materialize_true, materialize_false;
   Label* if_true = NULL;
   Label* if_false = NULL;
   Label* fall_through = NULL;
-  PrepareTest(&materialize_true, &materialize_false,
-              &if_true, &if_false, &fall_through);
+  context()->PrepareTest(&materialize_true, &materialize_false,
+                         &if_true, &if_false, &fall_through);
 
   // Get the frame pointer for the calling frame.
   __ mov(eax, Operand(ebp, StandardFrameConstants::kCallerFPOffset));
 
   // Skip the arguments adaptor frame if it exists.
   Label check_frame_marker;
   __ cmp(Operand(eax, StandardFrameConstants::kContextOffset),
          Immediate(Smi::FromInt(StackFrame::ARGUMENTS_ADAPTOR)));
   __ j(not_equal, &check_frame_marker);
   __ mov(eax, Operand(eax, StandardFrameConstants::kCallerFPOffset));
 
   // Check the marker in the calling frame.
   __ bind(&check_frame_marker);
   __ cmp(Operand(eax, StandardFrameConstants::kMarkerOffset),
          Immediate(Smi::FromInt(StackFrame::CONSTRUCT)));
   Split(equal, if_true, if_false, fall_through);
 
-  Apply(context_, if_true, if_false);
+  context()->Plug(if_true, if_false);
 }
 
 
 void FullCodeGenerator::EmitObjectEquals(ZoneList<Expression*>* args) {
   ASSERT(args->length() == 2);
 
   // Load the two objects into registers and perform the comparison.
-  VisitForValue(args->at(0), kStack);
-  VisitForValue(args->at(1), kAccumulator);
+  VisitForStackValue(args->at(0));
+  VisitForAccumulatorValue(args->at(1));
 
   Label materialize_true, materialize_false;
   Label* if_true = NULL;
   Label* if_false = NULL;
   Label* fall_through = NULL;
-  PrepareTest(&materialize_true, &materialize_false,
-              &if_true, &if_false, &fall_through);
+  context()->PrepareTest(&materialize_true, &materialize_false,
+                         &if_true, &if_false, &fall_through);
 
   __ pop(ebx);
   __ cmp(eax, Operand(ebx));
   Split(equal, if_true, if_false, fall_through);
 
-  Apply(context_, if_true, if_false);
+  context()->Plug(if_true, if_false);
 }
 
 
 void FullCodeGenerator::EmitArguments(ZoneList<Expression*>* args) {
   ASSERT(args->length() == 1);
 
   // ArgumentsAccessStub expects the key in edx and the formal
   // parameter count in eax.
-  VisitForValue(args->at(0), kAccumulator);
+  VisitForAccumulatorValue(args->at(0));
   __ mov(edx, eax);
   __ mov(eax, Immediate(Smi::FromInt(scope()->num_parameters())));
   ArgumentsAccessStub stub(ArgumentsAccessStub::READ_ELEMENT);
   __ CallStub(&stub);
-  Apply(context_, eax);
+  context()->Plug(eax);
 }
 
 
 void FullCodeGenerator::EmitArgumentsLength(ZoneList<Expression*>* args) {
   ASSERT(args->length() == 0);
 
   Label exit;
   // Get the number of formal parameters.
   __ Set(eax, Immediate(Smi::FromInt(scope()->num_parameters())));
 
   // Check if the calling frame is an arguments adaptor frame.
   __ mov(ebx, Operand(ebp, StandardFrameConstants::kCallerFPOffset));
   __ cmp(Operand(ebx, StandardFrameConstants::kContextOffset),
          Immediate(Smi::FromInt(StackFrame::ARGUMENTS_ADAPTOR)));
   __ j(not_equal, &exit);
 
   // Arguments adaptor case: Read the arguments length from the
   // adaptor frame.
   __ mov(eax, Operand(ebx, ArgumentsAdaptorFrameConstants::kLengthOffset));
 
   __ bind(&exit);
   if (FLAG_debug_code) __ AbortIfNotSmi(eax);
-  Apply(context_, eax);
+  context()->Plug(eax);
 }
 
 
 void FullCodeGenerator::EmitClassOf(ZoneList<Expression*>* args) {
   ASSERT(args->length() == 1);
   Label done, null, function, non_function_constructor;
 
-  VisitForValue(args->at(0), kAccumulator);
+  VisitForAccumulatorValue(args->at(0));
 
   // If the object is a smi, we return null.
   __ test(eax, Immediate(kSmiTagMask));
   __ j(zero, &null);
 
   // Check that the object is a JS object but take special care of JS
   // functions to make sure they have 'Function' as their class.
   __ CmpObjectType(eax, FIRST_JS_OBJECT_TYPE, eax);  // Map is now in eax.
   __ j(below, &null);
 
@@ skipping 26 matching lines @@
   __ mov(eax, Factory::Object_symbol());
   __ jmp(&done);
 
   // Non-JS objects have class null.
   __ bind(&null);
   __ mov(eax, Factory::null_value());
 
   // All done.
   __ bind(&done);
 
-  Apply(context_, eax);
+  context()->Plug(eax);
 }
 
 
 void FullCodeGenerator::EmitLog(ZoneList<Expression*>* args) {
   // Conditionally generate a log call.
   // Args:
   //   0 (literal string): The type of logging (corresponds to the flags).
   //     This is used to determine whether or not to generate the log call.
   //   1 (string): Format string.  Access the string at argument index 2
   //     with '%2s' (see Logger::LogRuntime for all the formats).
   //   2 (array): Arguments to the format string.
   ASSERT_EQ(args->length(), 3);
 #ifdef ENABLE_LOGGING_AND_PROFILING
   if (CodeGenerator::ShouldGenerateLog(args->at(0))) {
-    VisitForValue(args->at(1), kStack);
-    VisitForValue(args->at(2), kStack);
+    VisitForStackValue(args->at(1));
+    VisitForStackValue(args->at(2));
     __ CallRuntime(Runtime::kLog, 2);
   }
 #endif
   // Finally, we're expected to leave a value on the top of the stack.
   __ mov(eax, Factory::undefined_value());
-  Apply(context_, eax);
+  context()->Plug(eax);
 }
 
 
 void FullCodeGenerator::EmitRandomHeapNumber(ZoneList<Expression*>* args) {
   ASSERT(args->length() == 0);
 
   Label slow_allocate_heapnumber;
   Label heapnumber_allocated;
 
   __ AllocateHeapNumber(edi, ebx, ecx, &slow_allocate_heapnumber);
@@ skipping 27 matching lines @@
     __ mov(FieldOperand(edi, HeapNumber::kExponentOffset),
            Immediate(0x41300000));
     __ mov(FieldOperand(edi, HeapNumber::kMantissaOffset), eax);
     __ fld_d(FieldOperand(edi, HeapNumber::kValueOffset));
     __ mov(FieldOperand(edi, HeapNumber::kMantissaOffset), Immediate(0));
     __ fld_d(FieldOperand(edi, HeapNumber::kValueOffset));
     __ fsubp(1);
     __ fstp_d(FieldOperand(edi, HeapNumber::kValueOffset));
   }
   __ mov(eax, edi);
-  Apply(context_, eax);
+  context()->Plug(eax);
 }
 
 
 void FullCodeGenerator::EmitSubString(ZoneList<Expression*>* args) {
   // Load the arguments on the stack and call the stub.
   SubStringStub stub;
   ASSERT(args->length() == 3);
-  VisitForValue(args->at(0), kStack);
-  VisitForValue(args->at(1), kStack);
-  VisitForValue(args->at(2), kStack);
+  VisitForStackValue(args->at(0));
+  VisitForStackValue(args->at(1));
+  VisitForStackValue(args->at(2));
   __ CallStub(&stub);
-  Apply(context_, eax);
+  context()->Plug(eax);
 }
 
 
 void FullCodeGenerator::EmitRegExpExec(ZoneList<Expression*>* args) {
   // Load the arguments on the stack and call the stub.
   RegExpExecStub stub;
   ASSERT(args->length() == 4);
-  VisitForValue(args->at(0), kStack);
-  VisitForValue(args->at(1), kStack);
-  VisitForValue(args->at(2), kStack);
-  VisitForValue(args->at(3), kStack);
+  VisitForStackValue(args->at(0));
+  VisitForStackValue(args->at(1));
+  VisitForStackValue(args->at(2));
+  VisitForStackValue(args->at(3));
   __ CallStub(&stub);
-  Apply(context_, eax);
+  context()->Plug(eax);
 }
 
 
 void FullCodeGenerator::EmitValueOf(ZoneList<Expression*>* args) {
   ASSERT(args->length() == 1);
 
-  VisitForValue(args->at(0), kAccumulator);  // Load the object.
+  VisitForAccumulatorValue(args->at(0));  // Load the object.
 
   Label done;
   // If the object is a smi return the object.
   __ test(eax, Immediate(kSmiTagMask));
   __ j(zero, &done);
   // If the object is not a value type, return the object.
   __ CmpObjectType(eax, JS_VALUE_TYPE, ebx);
   __ j(not_equal, &done);
   __ mov(eax, FieldOperand(eax, JSValue::kValueOffset));
 
   __ bind(&done);
-  Apply(context_, eax);
+  context()->Plug(eax);
 }
 
 
 void FullCodeGenerator::EmitMathPow(ZoneList<Expression*>* args) {
   // Load the arguments on the stack and call the runtime function.
   ASSERT(args->length() == 2);
-  VisitForValue(args->at(0), kStack);
-  VisitForValue(args->at(1), kStack);
+  VisitForStackValue(args->at(0));
+  VisitForStackValue(args->at(1));
   __ CallRuntime(Runtime::kMath_pow, 2);
-  Apply(context_, eax);
+  context()->Plug(eax);
 }
 
 
 void FullCodeGenerator::EmitSetValueOf(ZoneList<Expression*>* args) {
   ASSERT(args->length() == 2);
 
-  VisitForValue(args->at(0), kStack);  // Load the object.
-  VisitForValue(args->at(1), kAccumulator);  // Load the value.
+  VisitForStackValue(args->at(0));  // Load the object.
+  VisitForAccumulatorValue(args->at(1));  // Load the value.
   __ pop(ebx);  // eax = value. ebx = object.
 
   Label done;
   // If the object is a smi, return the value.
   __ test(ebx, Immediate(kSmiTagMask));
   __ j(zero, &done);
 
   // If the object is not a value type, return the value.
   __ CmpObjectType(ebx, JS_VALUE_TYPE, ecx);
   __ j(not_equal, &done);
 
   // Store the value.
   __ mov(FieldOperand(ebx, JSValue::kValueOffset), eax);
   // Update the write barrier.  Save the value as it will be
   // overwritten by the write barrier code and is needed afterward.
   __ mov(edx, eax);
   __ RecordWrite(ebx, JSValue::kValueOffset, edx, ecx);
 
   __ bind(&done);
-  Apply(context_, eax);
+  context()->Plug(eax);
 }
 
 
 void FullCodeGenerator::EmitNumberToString(ZoneList<Expression*>* args) {
   ASSERT_EQ(args->length(), 1);
 
   // Load the argument on the stack and call the stub.
-  VisitForValue(args->at(0), kStack);
+  VisitForStackValue(args->at(0));
 
   NumberToStringStub stub;
   __ CallStub(&stub);
-  Apply(context_, eax);
+  context()->Plug(eax);
 }
 
 
 void FullCodeGenerator::EmitStringCharFromCode(ZoneList<Expression*>* args) {
   ASSERT(args->length() == 1);
 
-  VisitForValue(args->at(0), kAccumulator);
+  VisitForAccumulatorValue(args->at(0));
 
   Label done;
   StringCharFromCodeGenerator generator(eax, ebx);
   generator.GenerateFast(masm_);
   __ jmp(&done);
 
   NopRuntimeCallHelper call_helper;
   generator.GenerateSlow(masm_, call_helper);
 
   __ bind(&done);
-  Apply(context_, ebx);
+  context()->Plug(ebx);
 }
 
 
 void FullCodeGenerator::EmitStringCharCodeAt(ZoneList<Expression*>* args) {
   ASSERT(args->length() == 2);
 
-  VisitForValue(args->at(0), kStack);
-  VisitForValue(args->at(1), kAccumulator);
+  VisitForStackValue(args->at(0));
+  VisitForAccumulatorValue(args->at(1));
 
   Register object = ebx;
   Register index = eax;
   Register scratch = ecx;
   Register result = edx;
 
   __ pop(object);
 
   Label need_conversion;
   Label index_out_of_range;
@@ skipping 18 matching lines @@
   __ bind(&need_conversion);
   // Move the undefined value into the result register, which will
   // trigger conversion.
   __ Set(result, Immediate(Factory::undefined_value()));
   __ jmp(&done);
 
   NopRuntimeCallHelper call_helper;
   generator.GenerateSlow(masm_, call_helper);
 
   __ bind(&done);
-  Apply(context_, result);
+  context()->Plug(result);
 }
 
 
 void FullCodeGenerator::EmitStringCharAt(ZoneList<Expression*>* args) {
   ASSERT(args->length() == 2);
 
-  VisitForValue(args->at(0), kStack);
-  VisitForValue(args->at(1), kAccumulator);
+  VisitForStackValue(args->at(0));
+  VisitForAccumulatorValue(args->at(1));
 
   Register object = ebx;
   Register index = eax;
   Register scratch1 = ecx;
   Register scratch2 = edx;
   Register result = eax;
 
   __ pop(object);
 
   Label need_conversion;
@@ skipping 20 matching lines @@
   __ bind(&need_conversion);
   // Move smi zero into the result register, which will trigger
   // conversion.
   __ Set(result, Immediate(Smi::FromInt(0)));
   __ jmp(&done);
 
   NopRuntimeCallHelper call_helper;
   generator.GenerateSlow(masm_, call_helper);
 
   __ bind(&done);
-  Apply(context_, result);
+  context()->Plug(result);
 }
 
 
 void FullCodeGenerator::EmitStringAdd(ZoneList<Expression*>* args) {
   ASSERT_EQ(2, args->length());
 
-  VisitForValue(args->at(0), kStack);
-  VisitForValue(args->at(1), kStack);
+  VisitForStackValue(args->at(0));
+  VisitForStackValue(args->at(1));
 
   StringAddStub stub(NO_STRING_ADD_FLAGS);
   __ CallStub(&stub);
-  Apply(context_, eax);
+  context()->Plug(eax);
 }
 
 
 void FullCodeGenerator::EmitStringCompare(ZoneList<Expression*>* args) {
   ASSERT_EQ(2, args->length());
 
-  VisitForValue(args->at(0), kStack);
-  VisitForValue(args->at(1), kStack);
+  VisitForStackValue(args->at(0));
+  VisitForStackValue(args->at(1));
 
   StringCompareStub stub;
   __ CallStub(&stub);
-  Apply(context_, eax);
+  context()->Plug(eax);
 }
 
 
 void FullCodeGenerator::EmitMathSin(ZoneList<Expression*>* args) {
   // Load the argument on the stack and call the stub.
   TranscendentalCacheStub stub(TranscendentalCache::SIN);
   ASSERT(args->length() == 1);
-  VisitForValue(args->at(0), kStack);
+  VisitForStackValue(args->at(0));
   __ CallStub(&stub);
-  Apply(context_, eax);
+  context()->Plug(eax);
 }
 
 
 void FullCodeGenerator::EmitMathCos(ZoneList<Expression*>* args) {
   // Load the argument on the stack and call the stub.
   TranscendentalCacheStub stub(TranscendentalCache::COS);
   ASSERT(args->length() == 1);
-  VisitForValue(args->at(0), kStack);
+  VisitForStackValue(args->at(0));
   __ CallStub(&stub);
-  Apply(context_, eax);
+  context()->Plug(eax);
 }
 
 
 void FullCodeGenerator::EmitMathSqrt(ZoneList<Expression*>* args) {
   // Load the argument on the stack and call the runtime function.
   ASSERT(args->length() == 1);
-  VisitForValue(args->at(0), kStack);
+  VisitForStackValue(args->at(0));
   __ CallRuntime(Runtime::kMath_sqrt, 1);
-  Apply(context_, eax);
+  context()->Plug(eax);
 }
 
 
 void FullCodeGenerator::EmitCallFunction(ZoneList<Expression*>* args) {
   ASSERT(args->length() >= 2);
 
   int arg_count = args->length() - 2;  // For receiver and function.
-  VisitForValue(args->at(0), kStack);  // Receiver.
+  VisitForStackValue(args->at(0));  // Receiver.
   for (int i = 0; i < arg_count; i++) {
-    VisitForValue(args->at(i + 1), kStack);
+    VisitForStackValue(args->at(i + 1));
   }
-  VisitForValue(args->at(arg_count + 1), kAccumulator);  // Function.
+  VisitForAccumulatorValue(args->at(arg_count + 1));  // Function.
 
   // InvokeFunction requires function in edi. Move it in there.
   if (!result_register().is(edi)) __ mov(edi, result_register());
   ParameterCount count(arg_count);
   __ InvokeFunction(edi, count, CALL_FUNCTION);
   __ mov(esi, Operand(ebp, StandardFrameConstants::kContextOffset));
-  Apply(context_, eax);
+  context()->Plug(eax);
 }
 
 
 void FullCodeGenerator::EmitRegExpConstructResult(ZoneList<Expression*>* args) {
   ASSERT(args->length() == 3);
-  VisitForValue(args->at(0), kStack);
-  VisitForValue(args->at(1), kStack);
-  VisitForValue(args->at(2), kStack);
+  VisitForStackValue(args->at(0));
+  VisitForStackValue(args->at(1));
+  VisitForStackValue(args->at(2));
   __ CallRuntime(Runtime::kRegExpConstructResult, 3);
-  Apply(context_, eax);
+  context()->Plug(eax);
 }
 
 
 void FullCodeGenerator::EmitSwapElements(ZoneList<Expression*>* args) {
   ASSERT(args->length() == 3);
-  VisitForValue(args->at(0), kStack);
-  VisitForValue(args->at(1), kStack);
-  VisitForValue(args->at(2), kStack);
+  VisitForStackValue(args->at(0));
+  VisitForStackValue(args->at(1));
+  VisitForStackValue(args->at(2));
   __ CallRuntime(Runtime::kSwapElements, 3);
-  Apply(context_, eax);
+  context()->Plug(eax);
 }
 
 
 void FullCodeGenerator::EmitGetFromCache(ZoneList<Expression*>* args) {
   ASSERT_EQ(2, args->length());
 
   ASSERT_NE(NULL, args->at(0)->AsLiteral());
   int cache_id = Smi::cast(*(args->at(0)->AsLiteral()->handle()))->value();
 
   Handle<FixedArray> jsfunction_result_caches(
       Top::global_context()->jsfunction_result_caches());
   if (jsfunction_result_caches->length() <= cache_id) {
     __ Abort("Attempt to use undefined cache.");
     __ mov(eax, Factory::undefined_value());
-    Apply(context_, eax);
+    context()->Plug(eax);
     return;
   }
 
-  VisitForValue(args->at(1), kAccumulator);
+  VisitForAccumulatorValue(args->at(1));
 
   Register key = eax;
   Register cache = ebx;
   Register tmp = ecx;
   __ mov(cache, ContextOperand(esi, Context::GLOBAL_INDEX));
   __ mov(cache,
          FieldOperand(cache, GlobalObject::kGlobalContextOffset));
   __ mov(cache, ContextOperand(cache, Context::JSFUNCTION_RESULT_CACHES_INDEX));
   __ mov(cache,
          FieldOperand(cache, FixedArray::OffsetOfElementAt(cache_id)));
 
   Label done, not_found;
   // tmp now holds finger offset as a smi.
   ASSERT(kSmiTag == 0 && kSmiTagSize == 1);
   __ mov(tmp, FieldOperand(cache, JSFunctionResultCache::kFingerOffset));
   __ cmp(key, CodeGenerator::FixedArrayElementOperand(cache, tmp));
   __ j(not_equal, &not_found);
 
   __ mov(eax, CodeGenerator::FixedArrayElementOperand(cache, tmp, 1));
   __ jmp(&done);
 
   __ bind(&not_found);
   // Call runtime to perform the lookup.
   __ push(cache);
   __ push(key);
   __ CallRuntime(Runtime::kGetFromCache, 2);
 
   __ bind(&done);
-  Apply(context_, eax);
+  context()->Plug(eax);
 }
 
 
 void FullCodeGenerator::EmitIsRegExpEquivalent(ZoneList<Expression*>* args) {
   ASSERT_EQ(2, args->length());
 
   Register right = eax;
   Register left = ebx;
   Register tmp = ecx;
 
-  VisitForValue(args->at(0), kStack);
-  VisitForValue(args->at(1), kAccumulator);
+  VisitForStackValue(args->at(0));
+  VisitForAccumulatorValue(args->at(1));
   __ pop(left);
 
   Label done, fail, ok;
   __ cmp(left, Operand(right));
   __ j(equal, &ok);
   // Fail if either is a non-HeapObject.
   __ mov(tmp, left);
   __ and_(Operand(tmp), right);
   __ test(Operand(tmp), Immediate(kSmiTagMask));
   __ j(zero, &fail);
   __ CmpObjectType(left, JS_REGEXP_TYPE, tmp);
   __ j(not_equal, &fail);
   __ cmp(tmp, FieldOperand(right, HeapObject::kMapOffset));
   __ j(not_equal, &fail);
   __ mov(tmp, FieldOperand(left, JSRegExp::kDataOffset));
   __ cmp(tmp, FieldOperand(right, JSRegExp::kDataOffset));
   __ j(equal, &ok);
   __ bind(&fail);
   __ mov(eax, Immediate(Factory::false_value()));
   __ jmp(&done);
   __ bind(&ok);
   __ mov(eax, Immediate(Factory::true_value()));
   __ bind(&done);
 
-  Apply(context_, eax);
+  context()->Plug(eax);
 }
 
 
 void FullCodeGenerator::EmitHasCachedArrayIndex(ZoneList<Expression*>* args) {
   ASSERT(args->length() == 1);
 
-  VisitForValue(args->at(0), kAccumulator);
+  VisitForAccumulatorValue(args->at(0));
 
   if (FLAG_debug_code) {
     __ AbortIfNotString(eax);
   }
 
   Label materialize_true, materialize_false;
   Label* if_true = NULL;
   Label* if_false = NULL;
   Label* fall_through = NULL;
-  PrepareTest(&materialize_true, &materialize_false,
-              &if_true, &if_false, &fall_through);
+  context()->PrepareTest(&materialize_true, &materialize_false,
+                         &if_true, &if_false, &fall_through);
 
   __ test(FieldOperand(eax, String::kHashFieldOffset),
           Immediate(String::kContainsCachedArrayIndexMask));
   Split(zero, if_true, if_false, fall_through);
 
-  Apply(context_, if_true, if_false);
+  context()->Plug(if_true, if_false);
 }
 
 
 void FullCodeGenerator::EmitGetCachedArrayIndex(ZoneList<Expression*>* args) {
   ASSERT(args->length() == 1);
 
-  VisitForValue(args->at(0), kAccumulator);
+  VisitForAccumulatorValue(args->at(0));
 
   if (FLAG_debug_code) {
     __ AbortIfNotString(eax);
   }
 
   __ mov(eax, FieldOperand(eax, String::kHashFieldOffset));
   __ IndexFromHash(eax, eax);
 
-  Apply(context_, eax);
+  context()->Plug(eax);
 }
 
 
 void FullCodeGenerator::VisitCallRuntime(CallRuntime* expr) {
   Handle<String> name = expr->name();
   if (name->length() > 0 && name->Get(0) == '_') {
     Comment cmnt(masm_, "[ InlineRuntimeCall");
     EmitInlineRuntimeCall(expr);
     return;
   }
 
   Comment cmnt(masm_, "[ CallRuntime");
   ZoneList<Expression*>* args = expr->arguments();
 
   if (expr->is_jsruntime()) {
     // Prepare for calling JS runtime function.
     __ mov(eax, CodeGenerator::GlobalObject());
     __ push(FieldOperand(eax, GlobalObject::kBuiltinsOffset));
   }
 
   // Push the arguments ("left-to-right").
   int arg_count = args->length();
   for (int i = 0; i < arg_count; i++) {
-    VisitForValue(args->at(i), kStack);
+    VisitForStackValue(args->at(i));
   }
 
   if (expr->is_jsruntime()) {
     // Call the JS runtime function via a call IC.
     __ Set(ecx, Immediate(expr->name()));
     InLoopFlag in_loop = (loop_depth() > 0) ? IN_LOOP : NOT_IN_LOOP;
     Handle<Code> ic = CodeGenerator::ComputeCallInitialize(arg_count, in_loop);
     __ call(ic, RelocInfo::CODE_TARGET);
       // Restore context register.
     __ mov(esi, Operand(ebp, StandardFrameConstants::kContextOffset));
   } else {
     // Call the C runtime function.
     __ CallRuntime(expr->function(), arg_count);
   }
-  Apply(context_, eax);
+  context()->Plug(eax);
 }
 
 
 void FullCodeGenerator::VisitUnaryOperation(UnaryOperation* expr) {
   switch (expr->op()) {
     case Token::DELETE: {
       Comment cmnt(masm_, "[ UnaryOperation (DELETE)");
       Property* prop = expr->expression()->AsProperty();
       Variable* var = expr->expression()->AsVariableProxy()->AsVariable();
       if (prop == NULL && var == NULL) {
         // Result of deleting non-property, non-variable reference is true.
         // The subexpression may have side effects.
         VisitForEffect(expr->expression());
-        Apply(context_, true);
+        context()->Plug(true);
       } else if (var != NULL &&
                  !var->is_global() &&
                  var->slot() != NULL &&
                  var->slot()->type() != Slot::LOOKUP) {
         // Result of deleting non-global, non-dynamic variables is false.
         // The subexpression does not have side effects.
-        Apply(context_, false);
+        context()->Plug(false);
       } else {
         // Property or variable reference.  Call the delete builtin with
         // object and property name as arguments.
         if (prop != NULL) {
-          VisitForValue(prop->obj(), kStack);
-          VisitForValue(prop->key(), kStack);
+          VisitForStackValue(prop->obj());
+          VisitForStackValue(prop->key());
         } else if (var->is_global()) {
           __ push(CodeGenerator::GlobalObject());
           __ push(Immediate(var->name()));
         } else {
           // Non-global variable.  Call the runtime to look up the context
           // where the variable was introduced.
           __ push(context_register());
           __ push(Immediate(var->name()));
           __ CallRuntime(Runtime::kLookupContext, 2);
           __ push(eax);
           __ push(Immediate(var->name()));
         }
         __ InvokeBuiltin(Builtins::DELETE, CALL_FUNCTION);
-        Apply(context_, eax);
+        context()->Plug(eax);
       }
       break;
     }
 
     case Token::VOID: {
       Comment cmnt(masm_, "[ UnaryOperation (VOID)");
       VisitForEffect(expr->expression());
-      switch (context_) {
-        case Expression::kUninitialized:
-          UNREACHABLE();
-          break;
-        case Expression::kEffect:
-          break;
-        case Expression::kValue:
-          switch (location_) {
-            case kAccumulator:
-              __ mov(result_register(), Factory::undefined_value());
-              break;
-            case kStack:
-              __ push(Immediate(Factory::undefined_value()));
-              break;
-          }
-          break;
-        case Expression::kTest:
-          __ jmp(false_label_);
-          break;
-      }
+      context()->Plug(Factory::undefined_value());
       break;
     }
 
     case Token::NOT: {
       Comment cmnt(masm_, "[ UnaryOperation (NOT)");
 
       Label materialize_true, materialize_false;
       Label* if_true = NULL;
       Label* if_false = NULL;
       Label* fall_through = NULL;
       // Notice that the labels are swapped.
-      PrepareTest(&materialize_true, &materialize_false,
-                  &if_false, &if_true, &fall_through);
+      context()->PrepareTest(&materialize_true, &materialize_false,
+                             &if_false, &if_true, &fall_through);
       VisitForControl(expr->expression(), if_true, if_false, fall_through);
-      Apply(context_, if_false, if_true);  // Labels swapped.
+      context()->Plug(if_false, if_true);  // Labels swapped.
       break;
     }
 
     case Token::TYPEOF: {
       Comment cmnt(masm_, "[ UnaryOperation (TYPEOF)");
-      VisitForTypeofValue(expr->expression(), kStack);
+      { StackValueContext context(this);
+        VisitForTypeofValue(expr->expression());
+      }
       __ CallRuntime(Runtime::kTypeof, 1);
-      Apply(context_, eax);
+      context()->Plug(eax);
       break;
     }
 
     case Token::ADD: {
       Comment cmt(masm_, "[ UnaryOperation (ADD)");
-      VisitForValue(expr->expression(), kAccumulator);
+      VisitForAccumulatorValue(expr->expression());
       Label no_conversion;
       __ test(result_register(), Immediate(kSmiTagMask));
       __ j(zero, &no_conversion);
       __ push(result_register());
       __ InvokeBuiltin(Builtins::TO_NUMBER, CALL_FUNCTION);
       __ bind(&no_conversion);
-      Apply(context_, result_register());
+      context()->Plug(result_register());
       break;
     }
 
     case Token::SUB: {
       Comment cmt(masm_, "[ UnaryOperation (SUB)");
       bool can_overwrite = expr->expression()->ResultOverwriteAllowed();
       UnaryOverwriteMode overwrite =
           can_overwrite ? UNARY_OVERWRITE : UNARY_NO_OVERWRITE;
       GenericUnaryOpStub stub(Token::SUB, overwrite);
       // GenericUnaryOpStub expects the argument to be in the
       // accumulator register eax.
-      VisitForValue(expr->expression(), kAccumulator);
+      VisitForAccumulatorValue(expr->expression());
       __ CallStub(&stub);
-      Apply(context_, eax);
+      context()->Plug(eax);
       break;
     }
 
     case Token::BIT_NOT: {
       Comment cmt(masm_, "[ UnaryOperation (BIT_NOT)");
       // The generic unary operation stub expects the argument to be
       // in the accumulator register eax.
-      VisitForValue(expr->expression(), kAccumulator);
+      VisitForAccumulatorValue(expr->expression());
       Label done;
       if (ShouldInlineSmiCase(expr->op())) {
         Label call_stub;
         __ test(eax, Immediate(kSmiTagMask));
         __ j(not_zero, &call_stub);
         __ lea(eax, Operand(eax, kSmiTagMask));
         __ not_(eax);
         __ jmp(&done);
         __ bind(&call_stub);
       }
       bool overwrite = expr->expression()->ResultOverwriteAllowed();
       UnaryOverwriteMode mode =
           overwrite ? UNARY_OVERWRITE : UNARY_NO_OVERWRITE;
       GenericUnaryOpStub stub(Token::BIT_NOT, mode);
       __ CallStub(&stub);
       __ bind(&done);
-      Apply(context_, eax);
+      context()->Plug(eax);
       break;
     }
 
     default:
       UNREACHABLE();
   }
 }
 
 
 void FullCodeGenerator::VisitCountOperation(CountOperation* expr) {
@@ skipping 15 matching lines @@
   // In case of a property we use the uninitialized expression context
   // of the key to detect a named property.
   if (prop != NULL) {
     assign_type =
         (prop->key()->IsPropertyName()) ? NAMED_PROPERTY : KEYED_PROPERTY;
   }
 
   // Evaluate expression and get value.
   if (assign_type == VARIABLE) {
     ASSERT(expr->expression()->AsVariableProxy()->var() != NULL);
-    Location saved_location = location_;
-    location_ = kAccumulator;
-    EmitVariableLoad(expr->expression()->AsVariableProxy()->var(),
-                     Expression::kValue);
-    location_ = saved_location;
+    AccumulatorValueContext context(this);
+    EmitVariableLoad(expr->expression()->AsVariableProxy()->var());
   } else {
     // Reserve space for result of postfix operation.
-    if (expr->is_postfix() && context_ != Expression::kEffect) {
+    if (expr->is_postfix() && !context()->IsEffect()) {
       __ push(Immediate(Smi::FromInt(0)));
     }
     if (assign_type == NAMED_PROPERTY) {
       // Put the object both on the stack and in the accumulator.
-      VisitForValue(prop->obj(), kAccumulator);
+      VisitForAccumulatorValue(prop->obj());
       __ push(eax);
       EmitNamedPropertyLoad(prop);
     } else {
-      VisitForValue(prop->obj(), kStack);
-      VisitForValue(prop->key(), kAccumulator);
+      VisitForStackValue(prop->obj());
+      VisitForAccumulatorValue(prop->key());
       __ mov(edx, Operand(esp, 0));
       __ push(eax);
       EmitKeyedPropertyLoad(prop);
     }
   }
 
   // Call ToNumber only if operand is not a smi.
   Label no_conversion;
   if (ShouldInlineSmiCase(expr->op())) {
     __ test(eax, Immediate(kSmiTagMask));
     __ j(zero, &no_conversion);
   }
   __ push(eax);
   __ InvokeBuiltin(Builtins::TO_NUMBER, CALL_FUNCTION);
   __ bind(&no_conversion);
 
   // Save result for postfix expressions.
   if (expr->is_postfix()) {
-    switch (context_) {
-      case Expression::kUninitialized:
-        UNREACHABLE();
-      case Expression::kEffect:
-        // Do not save result.
-        break;
-      case Expression::kValue:
-      case Expression::kTest:
-        // Save the result on the stack. If we have a named or keyed property
-        // we store the result under the receiver that is currently on top
-        // of the stack.
-        switch (assign_type) {
-          case VARIABLE:
-            __ push(eax);
-            break;
-          case NAMED_PROPERTY:
-            __ mov(Operand(esp, kPointerSize), eax);
-            break;
-          case KEYED_PROPERTY:
-            __ mov(Operand(esp, 2 * kPointerSize), eax);
-            break;
-        }
-        break;
+    if (!context()->IsEffect()) {
+      // Save the result on the stack. If we have a named or keyed property
+      // we store the result under the receiver that is currently on top
+      // of the stack.
+      switch (assign_type) {
+        case VARIABLE:
+          __ push(eax);
+          break;
+        case NAMED_PROPERTY:
+          __ mov(Operand(esp, kPointerSize), eax);
+          break;
+        case KEYED_PROPERTY:
+          __ mov(Operand(esp, 2 * kPointerSize), eax);
+          break;
+      }
     }
   }
 
   // Inline smi case if we are in a loop.
   Label stub_call, done;
   if (ShouldInlineSmiCase(expr->op())) {
     if (expr->op() == Token::INC) {
       __ add(Operand(eax), Immediate(Smi::FromInt(1)));
     } else {
       __ sub(Operand(eax), Immediate(Smi::FromInt(1)));
@@ skipping 17 matching lines @@
                            NO_GENERIC_BINARY_FLAGS,
                            TypeInfo::Unknown());
   stub.GenerateCall(masm(), eax, Smi::FromInt(1));
   __ bind(&done);
 
   // Store the value returned in eax.
   switch (assign_type) {
     case VARIABLE:
       if (expr->is_postfix()) {
         // Perform the assignment as if via '='.
-        EmitVariableAssignment(expr->expression()->AsVariableProxy()->var(),
-                               Token::ASSIGN,
-                               Expression::kEffect);
-        // For all contexts except kEffect: We have the result on
+        {
+          EffectContext context(this);
+          EmitVariableAssignment(expr->expression()->AsVariableProxy()->var(),
+                                 Token::ASSIGN);
+        }
+        // For all contexts except EffectContext We have the result on
         // top of the stack.
-        if (context_ != Expression::kEffect) {
-          ApplyTOS(context_);
+        if (!context()->IsEffect()) {
+          context()->PlugTOS();
         }
       } else {
         // Perform the assignment as if via '='.
         EmitVariableAssignment(expr->expression()->AsVariableProxy()->var(),
-                               Token::ASSIGN,
-                               context_);
+                               Token::ASSIGN);
       }
       break;
     case NAMED_PROPERTY: {
       __ mov(ecx, prop->key()->AsLiteral()->handle());
       __ pop(edx);
       Handle<Code> ic(Builtins::builtin(Builtins::StoreIC_Initialize));
       __ call(ic, RelocInfo::CODE_TARGET);
       // This nop signals to the IC that there is no inlined code at the call
       // site for it to patch.
       __ nop();
       if (expr->is_postfix()) {
-        if (context_ != Expression::kEffect) {
-          ApplyTOS(context_);
+        if (!context()->IsEffect()) {
+          context()->PlugTOS();
         }
       } else {
-        Apply(context_, eax);
+        context()->Plug(eax);
       }
       break;
     }
     case KEYED_PROPERTY: {
       __ pop(ecx);
       __ pop(edx);
       Handle<Code> ic(Builtins::builtin(Builtins::KeyedStoreIC_Initialize));
       __ call(ic, RelocInfo::CODE_TARGET);
       // This nop signals to the IC that there is no inlined code at the call
       // site for it to patch.
       __ nop();
       if (expr->is_postfix()) {
         // Result is on the stack
-        if (context_ != Expression::kEffect) {
-          ApplyTOS(context_);
+        if (!context()->IsEffect()) {
+          context()->PlugTOS();
         }
       } else {
-        Apply(context_, eax);
+        context()->Plug(eax);
       }
       break;
     }
   }
 }
 
 
-void FullCodeGenerator::VisitForTypeofValue(Expression* expr, Location where) {
+void FullCodeGenerator::VisitForTypeofValue(Expression* expr) {
   VariableProxy* proxy = expr->AsVariableProxy();
+  ASSERT(!context()->IsEffect());
+  ASSERT(!context()->IsTest());
+
   if (proxy != NULL && !proxy->var()->is_this() && proxy->var()->is_global()) {
     Comment cmnt(masm_, "Global variable");
     __ mov(eax, CodeGenerator::GlobalObject());
     __ mov(ecx, Immediate(proxy->name()));
     Handle<Code> ic(Builtins::builtin(Builtins::LoadIC_Initialize));
     // Use a regular load, not a contextual load, to avoid a reference
     // error.
     __ call(ic, RelocInfo::CODE_TARGET);
-    if (where == kStack) __ push(eax);
+    context()->Plug(eax);
   } else if (proxy != NULL &&
              proxy->var()->slot() != NULL &&
              proxy->var()->slot()->type() == Slot::LOOKUP) {
     Label done, slow;
 
     // Generate code for loading from variables potentially shadowed
     // by eval-introduced variables.
     Slot* slot = proxy->var()->slot();
     EmitDynamicLoadFromSlotFastCase(slot, INSIDE_TYPEOF, &slow, &done);
 
     __ bind(&slow);
     __ push(esi);
     __ push(Immediate(proxy->name()));
     __ CallRuntime(Runtime::kLoadContextSlotNoReferenceError, 2);
     __ bind(&done);
 
-    if (where == kStack) __ push(eax);
+    context()->Plug(eax);
   } else {
     // This expression cannot throw a reference error at the top level.
-    VisitForValue(expr, where);
+    Visit(expr);
   }
 }
 
 
 bool FullCodeGenerator::TryLiteralCompare(Token::Value op,
                                           Expression* left,
                                           Expression* right,
                                           Label* if_true,
                                           Label* if_false,
                                           Label* fall_through) {
   if (op != Token::EQ && op != Token::EQ_STRICT) return false;
 
   // Check for the pattern: typeof <expression> == <string literal>.
   Literal* right_literal = right->AsLiteral();
   if (right_literal == NULL) return false;
   Handle<Object> right_literal_value = right_literal->handle();
   if (!right_literal_value->IsString()) return false;
   UnaryOperation* left_unary = left->AsUnaryOperation();
   if (left_unary == NULL || left_unary->op() != Token::TYPEOF) return false;
   Handle<String> check = Handle<String>::cast(right_literal_value);
 
-  VisitForTypeofValue(left_unary->expression(), kAccumulator);
+  { AccumulatorValueContext context(this);
+    VisitForTypeofValue(left_unary->expression());
+  }
+
   if (check->Equals(Heap::number_symbol())) {
     __ test(eax, Immediate(kSmiTagMask));
     __ j(zero, if_true);
     __ cmp(FieldOperand(eax, HeapObject::kMapOffset),
            Factory::heap_number_map());
     Split(equal, if_true, if_false, fall_through);
   } else if (check->Equals(Heap::string_symbol())) {
     __ test(eax, Immediate(kSmiTagMask));
     __ j(zero, if_false);
     // Check for undetectable objects => false.
@@ skipping 56 matching lines @@
   Comment cmnt(masm_, "[ CompareOperation");
   SetSourcePosition(expr->position());
 
   // Always perform the comparison for its control flow.  Pack the result
   // into the expression's context after the comparison is performed.
 
   Label materialize_true, materialize_false;
   Label* if_true = NULL;
   Label* if_false = NULL;
   Label* fall_through = NULL;
-  PrepareTest(&materialize_true, &materialize_false,
-              &if_true, &if_false, &fall_through);
+  context()->PrepareTest(&materialize_true, &materialize_false,
+                         &if_true, &if_false, &fall_through);
 
   // First we try a fast inlined version of the compare when one of
   // the operands is a literal.
   Token::Value op = expr->op();
   Expression* left = expr->left();
   Expression* right = expr->right();
   if (TryLiteralCompare(op, left, right, if_true, if_false, fall_through)) {
-    Apply(context_, if_true, if_false);
+    context()->Plug(if_true, if_false);
     return;
   }
 
-  VisitForValue(expr->left(), kStack);
+  VisitForStackValue(expr->left());
   switch (expr->op()) {
     case Token::IN:
-      VisitForValue(expr->right(), kStack);
+      VisitForStackValue(expr->right());
       __ InvokeBuiltin(Builtins::IN, CALL_FUNCTION);
       __ cmp(eax, Factory::true_value());
       Split(equal, if_true, if_false, fall_through);
       break;
 
     case Token::INSTANCEOF: {
-      VisitForValue(expr->right(), kStack);
+      VisitForStackValue(expr->right());
       InstanceofStub stub;
       __ CallStub(&stub);
       __ test(eax, Operand(eax));
       // The stub returns 0 for true.
       Split(zero, if_true, if_false, fall_through);
       break;
     }
 
     default: {
-      VisitForValue(expr->right(), kAccumulator);
+      VisitForAccumulatorValue(expr->right());
       Condition cc = no_condition;
       bool strict = false;
       switch (op) {
         case Token::EQ_STRICT:
           strict = true;
           // Fall through
         case Token::EQ:
           cc = equal;
           __ pop(edx);
           break;
@@ skipping 36 matching lines @@
 
       CompareStub stub(cc, strict);
       __ CallStub(&stub);
       __ test(eax, Operand(eax));
       Split(cc, if_true, if_false, fall_through);
     }
   }
 
   // Convert the result of the comparison into one expected for this
   // expression's context.
-  Apply(context_, if_true, if_false);
+  context()->Plug(if_true, if_false);
 }
 
 
 void FullCodeGenerator::VisitCompareToNull(CompareToNull* expr) {
   Label materialize_true, materialize_false;
   Label* if_true = NULL;
   Label* if_false = NULL;
   Label* fall_through = NULL;
-  PrepareTest(&materialize_true, &materialize_false,
-              &if_true, &if_false, &fall_through);
+  context()->PrepareTest(&materialize_true, &materialize_false,
+                         &if_true, &if_false, &fall_through);
 
-  VisitForValue(expr->expression(), kAccumulator);
+  VisitForAccumulatorValue(expr->expression());
   __ cmp(eax, Factory::null_value());
   if (expr->is_strict()) {
     Split(equal, if_true, if_false, fall_through);
   } else {
     __ j(equal, if_true);
     __ cmp(eax, Factory::undefined_value());
     __ j(equal, if_true);
     __ test(eax, Immediate(kSmiTagMask));
     __ j(zero, if_false);
     // It can be an undetectable object.
     __ mov(edx, FieldOperand(eax, HeapObject::kMapOffset));
     __ movzx_b(edx, FieldOperand(edx, Map::kBitFieldOffset));
     __ test(edx, Immediate(1 << Map::kIsUndetectable));
     Split(not_zero, if_true, if_false, fall_through);
   }
-  Apply(context_, if_true, if_false);
+  context()->Plug(if_true, if_false);
 }
 
 
 void FullCodeGenerator::VisitThisFunction(ThisFunction* expr) {
   __ mov(eax, Operand(ebp, JavaScriptFrameConstants::kFunctionOffset));
-  Apply(context_, eax);
+  context()->Plug(eax);
 }
 
 
 Register FullCodeGenerator::result_register() { return eax; }
 
 
 Register FullCodeGenerator::context_register() { return esi; }
 
 
 void FullCodeGenerator::StoreToFrameField(int frame_offset, Register value) {
@@ skipping 36 matching lines @@
   // And return.
   __ ret(0);
 }
 
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_IA32