[stubs] Optimize LoadGlobalViaContextStub and StoreGlobalViaContextStub.

src/ia32/code-stubs-ia32.cc

Index: src/ia32/code-stubs-ia32.cc
diff --git a/src/ia32/code-stubs-ia32.cc b/src/ia32/code-stubs-ia32.cc
index 2cc75bf11c3bf55b6c3674007116ef8ebd4ce615..c034b223d840edaf224b618086b1e8e8a27331af 100644
--- a/src/ia32/code-stubs-ia32.cc
+++ b/src/ia32/code-stubs-ia32.cc
@@ -5116,6 +5116,161 @@ void InternalArrayConstructorStub::Generate(MacroAssembler* masm) {
 }
 
 
+void LoadGlobalViaContextStub::Generate(MacroAssembler* masm) {
+  Register context_reg = esi;
+  Register slot_reg = ebx;
+  Register name_reg = ecx;
+  Register result_reg = eax;
+  Label slow_case;
+
+  // Go up context chain to the script context.
+  for (int i = 0; i < depth(); ++i) {
+    __ mov(result_reg, ContextOperand(context_reg, Context::PREVIOUS_INDEX));
+    context_reg = result_reg;
+  }
+
+  // Load the PropertyCell value at the specified slot.
+  __ mov(result_reg, ContextOperand(context_reg, slot_reg));
+  __ mov(result_reg, FieldOperand(result_reg, PropertyCell::kValueOffset));
+
+  // Check that value is not the_hole.
+  __ CompareRoot(result_reg, Heap::kTheHoleValueRootIndex);
+  __ j(equal, &slow_case, Label::kNear);
+  __ Ret();
+
+  // Fallback to the runtime.
+  __ bind(&slow_case);
+  __ SmiTag(slot_reg);
+  __ Pop(result_reg);  // Pop return address.
+  __ Push(slot_reg);
+  __ Push(name_reg);
+  __ Push(result_reg);  // Push return address.
+  __ TailCallRuntime(Runtime::kLoadGlobalViaContext, 2, 1);
+}
+
+
+void StoreGlobalViaContextStub::Generate(MacroAssembler* masm) {
+  Register context_reg = esi;
+  Register slot_reg = ebx;
+  Register name_reg = ecx;
+  Register value_reg = eax;
+  Register cell_reg = edi;
+  Register cell_details_reg = edx;
+  Label fast_heapobject_case, fast_smi_case, slow_case;
+
+  if (FLAG_debug_code) {
+    __ CompareRoot(value_reg, Heap::kTheHoleValueRootIndex);
+    __ Check(not_equal, kUnexpectedValue);
+    __ AssertName(name_reg);
+  }
+
+  // Go up context chain to the script context.
+  for (int i = 0; i < depth(); ++i) {
+    __ mov(cell_reg, ContextOperand(context_reg, Context::PREVIOUS_INDEX));
+    context_reg = cell_reg;
+  }
+
+  // Load the PropertyCell at the specified slot.
+  __ mov(cell_reg, ContextOperand(context_reg, slot_reg));
+
+  // Load PropertyDetails for the cell (actually only the cell_type and kind).
+  __ mov(cell_details_reg,
+         FieldOperand(cell_reg, PropertyCell::kDetailsOffset));
+  __ SmiUntag(cell_details_reg);
+  __ and_(cell_details_reg,
+          Immediate(PropertyDetails::PropertyCellTypeField::kMask |
+                    PropertyDetails::KindField::kMask));
+
+
+  // Check if PropertyCell holds mutable data.
+  Label not_mutable_data;
+  __ cmp(cell_details_reg,
+         Immediate(PropertyDetails::PropertyCellTypeField::encode(
+                       PropertyCellType::kMutable) |
+                   PropertyDetails::KindField::encode(kData)));
+  __ j(not_equal, &not_mutable_data);
+  __ JumpIfSmi(value_reg, &fast_smi_case);
+  __ bind(&fast_heapobject_case);
+  __ mov(FieldOperand(cell_reg, PropertyCell::kValueOffset), value_reg);
+  __ RecordWriteField(cell_reg, PropertyCell::kValueOffset, value_reg,
+                      cell_details_reg, kDontSaveFPRegs, EMIT_REMEMBERED_SET,
+                      OMIT_SMI_CHECK);
+  // RecordWriteField clobbers the value register, so we need to reload.
+  __ mov(value_reg, FieldOperand(cell_reg, PropertyCell::kValueOffset));
+  __ Ret();
+  __ bind(&not_mutable_data);
+
+  // Check if PropertyCell value matches the new value (relevant for Constant,
+  // ConstantType and Undefined cells).
+  Label not_same_value;
+  __ cmp(value_reg, FieldOperand(cell_reg, PropertyCell::kValueOffset));
+  __ j(not_equal, &not_same_value,
+       FLAG_debug_code ? Label::kFar : Label::kNear);
+  if (FLAG_debug_code) {
+    Label done;
+    // This can only be true for Constant, ConstantType and Undefined cells,
+    // because we never store the_hole via this stub.
+    __ cmp(cell_details_reg,
+           Immediate(PropertyDetails::PropertyCellTypeField::encode(
+                         PropertyCellType::kConstant) |
+                     PropertyDetails::KindField::encode(kData)));
+    __ j(equal, &done);
+    __ cmp(cell_details_reg,
+           Immediate(PropertyDetails::PropertyCellTypeField::encode(
+                         PropertyCellType::kConstantType) |
+                     PropertyDetails::KindField::encode(kData)));
+    __ j(equal, &done);
+    __ cmp(cell_details_reg,
+           Immediate(PropertyDetails::PropertyCellTypeField::encode(
+                         PropertyCellType::kUndefined) |
+                     PropertyDetails::KindField::encode(kData)));
+    __ Check(equal, kUnexpectedValue);
+    __ bind(&done);
+  }
+  __ Ret();
+  __ bind(&not_same_value);
+
+  // Check if PropertyCell contains data with constant type.
+  __ cmp(cell_details_reg,
+         Immediate(PropertyDetails::PropertyCellTypeField::encode(
+                       PropertyCellType::kConstantType) |
+                   PropertyDetails::KindField::encode(kData)));
+  __ j(not_equal, &slow_case, Label::kNear);
+
+  // Now either both old and new values must be SMIs or both must be heap
+  // objects with same map.
+  Label value_is_heap_object;
+  Register cell_value_reg = cell_details_reg;
+  __ mov(cell_value_reg, FieldOperand(cell_reg, PropertyCell::kValueOffset));
+  __ JumpIfNotSmi(value_reg, &value_is_heap_object, Label::kNear);
+  __ JumpIfNotSmi(cell_value_reg, &slow_case, Label::kNear);
+  // Old and new values are SMIs, no need for a write barrier here.
+  __ bind(&fast_smi_case);
+  __ mov(FieldOperand(cell_reg, PropertyCell::kValueOffset), value_reg);
+  __ Ret();
+  __ bind(&value_is_heap_object);
+  __ JumpIfSmi(cell_value_reg, &slow_case, Label::kNear);
+  Register cell_value_map_reg = cell_value_reg;
+  __ mov(cell_value_map_reg,
+         FieldOperand(cell_value_reg, HeapObject::kMapOffset));
+  __ cmp(cell_value_map_reg, FieldOperand(value_reg, HeapObject::kMapOffset));
+  __ j(equal, &fast_heapobject_case);
+
+  // Fallback to the runtime.
+  __ bind(&slow_case);
+  __ SmiTag(slot_reg);
+  __ Pop(cell_reg);  // Pop return address.
+  __ Push(slot_reg);
+  __ Push(name_reg);
+  __ Push(value_reg);
+  __ Push(cell_reg);  // Push return address.
+  __ TailCallRuntime(is_strict(language_mode())
+                         ? Runtime::kStoreGlobalViaContext_Strict
+                         : Runtime::kStoreGlobalViaContext_Sloppy,
+                     3, 1);
+}
+
+
 // Generates an Operand for saving parameters after PrepareCallApiFunction.
 static Operand ApiParameterOperand(int index) {
   return Operand(esp, index * kPointerSize);