[stubs] Optimize LoadGlobalViaContextStub and StoreGlobalViaContextStub.

src/mips/full-codegen-mips.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_MIPS
 
 // Note on Mips implementation:
 //
@@ skipping 1389 matching lines @@
 
 void FullCodeGenerator::EmitGlobalVariableLoad(VariableProxy* proxy,
                                                TypeofMode typeof_mode) {
   Variable* var = proxy->var();
   DCHECK(var->IsUnallocatedOrGlobalSlot() ||
          (var->IsLookupSlot() && var->mode() == DYNAMIC_GLOBAL));
   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());
-    __ li(LoadGlobalViaContextDescriptor::DepthRegister(),
-          Operand(Smi::FromInt(depth)));
-    __ li(LoadGlobalViaContextDescriptor::SlotRegister(),
-          Operand(Smi::FromInt(slot_index)));
-    __ li(LoadGlobalViaContextDescriptor::NameRegister(), Operand(var->name()));
-    LoadGlobalViaContextStub stub(isolate(), depth);
-    __ CallStub(&stub);
+    int const slot = var->index();
+    int const depth = scope()->ContextChainLength(var->scope());
+    if (depth <= LoadGlobalViaContextStub::kMaximumDepth) {
+      __ li(LoadGlobalViaContextDescriptor::SlotRegister(), Operand(slot));
+      __ li(LoadGlobalViaContextDescriptor::NameRegister(), var->name());
+      LoadGlobalViaContextStub stub(isolate(), depth);
+      __ CallStub(&stub);
+    } else {
+      __ Push(Smi::FromInt(slot));
+      __ Push(var->name());
+      __ CallRuntime(Runtime::kLoadGlobalViaContext, 2);
+    }
 
   } else {
     __ lw(LoadDescriptor::ReceiverRegister(), GlobalObjectOperand());
     __ li(LoadDescriptor::NameRegister(), Operand(var->name()));
     __ li(LoadDescriptor::SlotRegister(),
           Operand(SmiFromSlot(proxy->VariableFeedbackSlot())));
     CallLoadIC(typeof_mode);
   }
 }
 
@@ skipping 1264 matching lines @@
     __ mov(StoreDescriptor::ValueRegister(), result_register());
     __ li(StoreDescriptor::NameRegister(), Operand(var->name()));
     __ lw(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());
+    DCHECK(StoreGlobalViaContextDescriptor::ValueRegister().is(a0));
+    __ mov(StoreGlobalViaContextDescriptor::ValueRegister(), result_register());
     // Each var occupies two slots in the context: for reads and writes.
-    int slot_index = var->index() + 1;
-    int depth = scope()->ContextChainLength(var->scope());
-    __ li(StoreGlobalViaContextDescriptor::DepthRegister(),
-          Operand(Smi::FromInt(depth)));
-    __ li(StoreGlobalViaContextDescriptor::SlotRegister(),
-          Operand(Smi::FromInt(slot_index)));
-    __ li(StoreGlobalViaContextDescriptor::NameRegister(),
-          Operand(var->name()));
-    __ mov(StoreGlobalViaContextDescriptor::ValueRegister(), result_register());
-    StoreGlobalViaContextStub stub(isolate(), depth, language_mode());
-    __ CallStub(&stub);
+    int const slot = var->index() + 1;
+    int const depth = scope()->ContextChainLength(var->scope());
+    if (depth <= StoreGlobalViaContextStub::kMaximumDepth) {
+      __ li(StoreGlobalViaContextDescriptor::SlotRegister(), Operand(slot));
+      __ li(StoreGlobalViaContextDescriptor::NameRegister(), var->name());
+      StoreGlobalViaContextStub stub(isolate(), depth, language_mode());
+      __ CallStub(&stub);
+    } else {
+      __ Push(Smi::FromInt(slot));
+      __ Push(var->name());
+      __ Push(a0);
+      __ CallRuntime(is_strict(language_mode())
+                         ? Runtime::kStoreGlobalViaContext_Strict
+                         : Runtime::kStoreGlobalViaContext_Sloppy,
+                     3);
+    }
 
   } 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, a1);
     __ lw(a3, location);
     __ LoadRoot(t0, Heap::kTheHoleValueRootIndex);
     __ Branch(&assign, ne, a3, Operand(t0));
@@ skipping 2701 matching lines @@
          reinterpret_cast<uint32_t>(
              isolate->builtins()->OsrAfterStackCheck()->entry()));
   return OSR_AFTER_STACK_CHECK;
 }
 
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_TARGET_ARCH_MIPS