[stubs] Optimize LoadGlobalViaContextStub and StoreGlobalViaContextStub.

src/ia32/code-stubs-ia32.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_IA32
 
 #include "src/base/bits.h"
 #include "src/bootstrapper.h"
@@ skipping 5084 matching lines @@
   Label fast_elements_case;
   __ cmp(ecx, Immediate(FAST_ELEMENTS));
   __ j(equal, &fast_elements_case);
   GenerateCase(masm, FAST_HOLEY_ELEMENTS);
 
   __ bind(&fast_elements_case);
   GenerateCase(masm, FAST_ELEMENTS);
 }
 
 
+void LoadGlobalViaContextStub::Generate(MacroAssembler* masm) {
+  Register context_reg = esi;

[Igor Sheludko, 2015/07/18 20:52:43]

Same comments as for x64.

[Benedikt Meurer, 2015/07/24 05:18:29]

Acknowledged.

+  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);

[Igor Sheludko, 2015/07/18 20:52:43]

// Pop return address.

[Benedikt Meurer, 2015/07/24 05:18:29]

Done.

+  __ Push(slot_reg);
+  __ Push(name_reg);
+  __ Push(result_reg);
+  __ 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_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);
+  __ bind(&fast_case);
+  __ mov(FieldOperand(cell_reg, PropertyCell::kValueOffset), value_reg);
+  __ RecordWriteField(cell_reg, PropertyCell::kValueOffset, value_reg,
+                      cell_details_reg, kDontSaveFPRegs);
+  // 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
+  // and ConstantType 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 and ConstantType 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)));
+    __ 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.
+  __ 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_case);
+
+  // Fallback to the runtime.
+  __ bind(&slow_case);
+  __ SmiTag(slot_reg);
+  __ Pop(cell_reg);

[Igor Sheludko, 2015/07/18 20:52:43]

// Pop return address.

[Benedikt Meurer, 2015/07/24 05:18:29]

Done.

+  __ Push(slot_reg);
+  __ Push(name_reg);
+  __ Push(value_reg);
+  __ Push(cell_reg);
+  __ 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);
 }
 
 
 // Prepares stack to put arguments (aligns and so on). Reserves
 // space for return value if needed (assumes the return value is a handle).
 // Arguments must be stored in ApiParameterOperand(0), ApiParameterOperand(1)
 // etc. Saves context (esi). If space was reserved for return value then
@@ skipping 370 matching lines @@
                            Operand(ebp, 7 * kPointerSize), NULL);
 }
 
 
 #undef __
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_TARGET_ARCH_IA32