[stubs] Optimize LoadGlobalViaContextStub and StoreGlobalViaContextStub.

src/mips/full-codegen-mips.cc

Index: src/mips/full-codegen-mips.cc
diff --git a/src/mips/full-codegen-mips.cc b/src/mips/full-codegen-mips.cc
index d0904a6d84e215576f65c35b2b872c024aa0f6d8..b501413be8d5348bae7e87468541bca657d52114 100644
--- a/src/mips/full-codegen-mips.cc
+++ b/src/mips/full-codegen-mips.cc
@@ -1407,15 +1407,18 @@ void FullCodeGenerator::EmitGlobalVariableLoad(VariableProxy* proxy,
     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());
@@ -2700,18 +2703,25 @@ void FullCodeGenerator::EmitVariableAssignment(Variable* var, Token::Value op,
     // 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());
-    __ li(StoreGlobalViaContextDescriptor::DepthRegister(),
-          Operand(Smi::FromInt(depth)));
-    __ li(StoreGlobalViaContextDescriptor::SlotRegister(),
-          Operand(Smi::FromInt(slot_index)));
-    __ li(StoreGlobalViaContextDescriptor::NameRegister(),
-          Operand(var->name()));
+    DCHECK(StoreGlobalViaContextDescriptor::ValueRegister().is(a0));
     __ mov(StoreGlobalViaContextDescriptor::ValueRegister(), result_register());
-    StoreGlobalViaContextStub stub(isolate(), depth, language_mode());
-    __ CallStub(&stub);
+    // Each var occupies two slots in the context: for reads and writes.
+    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.