Loads and stores to global vars are now made via property cell shortcuts installed into parent scri…

src/x64/full-codegen-x64.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/v8.h"
 
 #if V8_TARGET_ARCH_X64
 
 #include "src/code-factory.h"
 #include "src/code-stubs.h"
@@ skipping 1436 matching lines @@
     __ jmp(done);
   }
 }
 
 
 void FullCodeGenerator::EmitGlobalVariableLoad(VariableProxy* proxy,
                                                TypeofState typeof_state) {
   Variable* var = proxy->var();
   DCHECK(var->IsUnallocatedOrGlobalSlot() ||
          (var->IsLookupSlot() && var->mode() == DYNAMIC_GLOBAL));
-  __ Move(LoadDescriptor::NameRegister(), var->name());
-  __ movp(LoadDescriptor::ReceiverRegister(), GlobalObjectOperand());
-  __ Move(LoadDescriptor::SlotRegister(),
-          SmiFromSlot(proxy->VariableFeedbackSlot()));
-  // Inside typeof use a regular load, not a contextual load, to avoid
-  // a reference error.
-  CallLoadIC(typeof_state == NOT_INSIDE_TYPEOF ? CONTEXTUAL : NOT_CONTEXTUAL);
+  if (var->IsGlobalSlot()) {
+    DCHECK(var->index() > 0);
+    DCHECK(var->IsStaticGlobalObjectProperty());
+    // Each var occupies two slots in the context: for reads and writes.
+    int slot_index = var->index();
+    int depth = scope()->ContextChainLength(var->scope());
+    __ Move(LoadGlobalViaContextDescriptor::DepthRegister(),
+            Smi::FromInt(depth));
+    __ Move(LoadGlobalViaContextDescriptor::SlotRegister(),
+            Smi::FromInt(slot_index));
+    __ Move(LoadGlobalViaContextDescriptor::NameRegister(), var->name());
+    LoadGlobalViaContextStub stub(isolate(), depth);
+    __ CallStub(&stub);
+
+  } else {
+    __ Move(LoadDescriptor::NameRegister(), var->name());
+    __ movp(LoadDescriptor::ReceiverRegister(), GlobalObjectOperand());
+    __ Move(LoadDescriptor::SlotRegister(),
+            SmiFromSlot(proxy->VariableFeedbackSlot()));
+    // Inside typeof use a regular load, not a contextual load, to avoid
+    // a reference error.
+    CallLoadIC(typeof_state == NOT_INSIDE_TYPEOF ? CONTEXTUAL : NOT_CONTEXTUAL);
+  }
 }
 
 
 void FullCodeGenerator::EmitVariableLoad(VariableProxy* proxy,
                                          TypeofState typeof_state) {
   // Record position before possible IC call.
   SetExpressionPosition(proxy);
   PrepareForBailoutForId(proxy->BeforeId(), NO_REGISTERS);
   Variable* var = proxy->var();
 
@@ skipping 1178 matching lines @@
   if (var->IsContextSlot()) {
     __ movp(rdx, rax);
     __ RecordWriteContextSlot(
         rcx, Context::SlotOffset(var->index()), rdx, rbx, kDontSaveFPRegs);
   }
 }
 
 
 void FullCodeGenerator::EmitVariableAssignment(Variable* var, Token::Value op,
                                                FeedbackVectorICSlot slot) {
-  if (var->IsUnallocatedOrGlobalSlot()) {
+  if (var->IsUnallocated()) {
     // Global var, const, or let.
     __ Move(StoreDescriptor::NameRegister(), var->name());
     __ movp(StoreDescriptor::ReceiverRegister(), GlobalObjectOperand());
     if (FLAG_vector_stores) EmitLoadStoreICSlot(slot);
     CallStoreIC();
 
+  } else if (var->IsGlobalSlot()) {
+    // Global var, const, or let.
+    DCHECK(var->index() > 0);
+    DCHECK(var->IsStaticGlobalObjectProperty());
+    // Each var occupies two slots in the context: for reads and writes.
+    int slot_index = var->index() + 1;
+    int depth = scope()->ContextChainLength(var->scope());
+    __ Move(StoreGlobalViaContextDescriptor::DepthRegister(),
+            Smi::FromInt(depth));
+    __ Move(StoreGlobalViaContextDescriptor::SlotRegister(),
+            Smi::FromInt(slot_index));
+    __ Move(StoreGlobalViaContextDescriptor::NameRegister(), var->name());
+    DCHECK(StoreGlobalViaContextDescriptor::ValueRegister().is(rax));
+    StoreGlobalViaContextStub stub(isolate(), depth, language_mode());
+    __ CallStub(&stub);
+
   } else if (var->mode() == LET && op != Token::INIT_LET) {
     // Non-initializing assignment to let variable needs a write barrier.
     DCHECK(!var->IsLookupSlot());
     DCHECK(var->IsStackAllocated() || var->IsContextSlot());
     Label assign;
     MemOperand location = VarOperand(var, rcx);
     __ movp(rdx, location);
     __ CompareRoot(rdx, Heap::kTheHoleValueRootIndex);
     __ j(not_equal, &assign, Label::kNear);
     __ Push(var->name());
@@ skipping 2804 matching lines @@
             Assembler::target_address_at(call_target_address,
                                          unoptimized_code));
   return OSR_AFTER_STACK_CHECK;
 }
 
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_TARGET_ARCH_X64