[stubs] Optimize LoadGlobalViaContextStub and StoreGlobalViaContextStub.

src/mips/code-stubs-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
 
 #include "src/base/bits.h"
 #include "src/bootstrapper.h"
@@ skipping 5252 matching lines @@
 
   Label fast_elements_case;
   __ Branch(&fast_elements_case, eq, a3, Operand(FAST_ELEMENTS));
   GenerateCase(masm, FAST_HOLEY_ELEMENTS);
 
   __ bind(&fast_elements_case);
   GenerateCase(masm, FAST_ELEMENTS);
 }
 
 
+void LoadGlobalViaContextStub::Generate(MacroAssembler* masm) {
+  Register context_reg = cp;
+  Register slot_reg = a2;
+  Register name_reg = a3;
+  Register result_reg = v0;
+  Label slow_case;
+
+  // Go up context chain to the script context.
+  for (int i = 0; i < depth(); ++i) {
+    __ lw(result_reg, ContextOperand(context_reg, Context::PREVIOUS_INDEX));
+    context_reg = result_reg;
+  }
+
+  // Load the PropertyCell value at the specified slot.
+  __ sll(at, slot_reg, kPointerSizeLog2);
+  __ Addu(at, at, Operand(cp));

[Igor Sheludko, 2015/07/24 11:10:01]

We should load the cell from context_reg here.

+  __ Addu(at, at, Context::SlotOffset(0));
+  __ lw(result_reg, MemOperand(at));
+  __ lw(result_reg, FieldMemOperand(result_reg, PropertyCell::kValueOffset));
+
+  // Check that value is not the_hole.
+  __ LoadRoot(at, Heap::kTheHoleValueRootIndex);
+  __ Branch(&slow_case, eq, result_reg, Operand(at));
+  __ Ret();
+
+  // Fallback to the runtime.
+  __ bind(&slow_case);
+  __ SmiTag(slot_reg);
+  __ Drop(1);  // Pop return address.
+  __ Push(slot_reg, name_reg, result_reg);
+  __ TailCallRuntime(Runtime::kLoadGlobalViaContext, 2, 1);
+}
+
+
+void StoreGlobalViaContextStub::Generate(MacroAssembler* masm) {
+  Register context_reg = cp;
+  Register slot_reg = a2;
+  Register name_reg = a3;
+  Register value_reg = a0;
+  Register cell_reg = t0;
+  Register cell_details_reg = t1;
+  Label fast_heapobject_case, fast_smi_case, slow_case;
+
+  if (FLAG_debug_code) {
+    __ LoadRoot(at, Heap::kTheHoleValueRootIndex);
+    __ Check(ne, kUnexpectedValue, value_reg, Operand(at));
+    __ AssertName(name_reg);
+  }
+
+  // Go up context chain to the script context.
+  for (int i = 0; i < depth(); ++i) {
+    __ lw(cell_reg, ContextOperand(context_reg, Context::PREVIOUS_INDEX));
+    context_reg = cell_reg;
+  }
+
+  // Load the PropertyCell at the specified slot.
+  __ sll(at, slot_reg, kPointerSizeLog2);
+  __ Addu(at, at, Operand(cp));

[Igor Sheludko, 2015/07/24 11:10:01]

Same here.

+  __ Addu(at, at, Context::SlotOffset(0));
+  __ lw(cell_reg, MemOperand(at));
+
+  // Load PropertyDetails for the cell (actually only the cell_type and kind).
+  __ lw(cell_details_reg,
+        FieldMemOperand(cell_reg, PropertyCell::kDetailsOffset));
+  __ SmiUntag(cell_details_reg);
+  __ And(cell_details_reg, cell_details_reg,
+         PropertyDetails::PropertyCellTypeField::kMask |
+             PropertyDetails::KindField::kMask);
+
+  // Check if PropertyCell holds mutable data.
+  Label not_mutable_data;
+  __ Branch(&not_mutable_data, ne, cell_details_reg,
+            Operand(PropertyDetails::PropertyCellTypeField::encode(
+                        PropertyCellType::kMutable) |
+                    PropertyDetails::KindField::encode(kData)));
+  __ JumpIfSmi(value_reg, &fast_smi_case);
+  __ bind(&fast_heapobject_case);
+  __ sw(value_reg, FieldMemOperand(cell_reg, PropertyCell::kValueOffset));
+  __ RecordWriteField(cell_reg, PropertyCell::kValueOffset, value_reg,
+                      cell_details_reg, kRAHasNotBeenSaved, kDontSaveFPRegs,
+                      EMIT_REMEMBERED_SET, OMIT_SMI_CHECK);
+  // RecordWriteField clobbers the value register, so we need to reload.
+  __ lw(value_reg, FieldMemOperand(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;
+  __ lw(at, FieldMemOperand(cell_reg, PropertyCell::kValueOffset));
+  __ Branch(&not_same_value, ne, value_reg, Operand(at));
+  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.
+    __ Branch(&done, eq, cell_details_reg,
+              Operand(PropertyDetails::PropertyCellTypeField::encode(
+                          PropertyCellType::kConstant) |
+                      PropertyDetails::KindField::encode(kData)));
+    __ Branch(&done, eq, cell_details_reg,
+              Operand(PropertyDetails::PropertyCellTypeField::encode(
+                          PropertyCellType::kConstantType) |
+                      PropertyDetails::KindField::encode(kData)));
+    __ Check(eq, kUnexpectedValue, cell_details_reg,
+             Operand(PropertyDetails::PropertyCellTypeField::encode(
+                         PropertyCellType::kUndefined) |
+                     PropertyDetails::KindField::encode(kData)));
+    __ bind(&done);
+  }
+  __ Ret();
+  __ bind(&not_same_value);
+
+  // Check if PropertyCell contains data with constant type.
+  __ Branch(&slow_case, ne, cell_details_reg,
+            Operand(PropertyDetails::PropertyCellTypeField::encode(
+                        PropertyCellType::kConstantType) |
+                    PropertyDetails::KindField::encode(kData)));
+
+  // 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;
+  __ lw(cell_value_reg, FieldMemOperand(cell_reg, PropertyCell::kValueOffset));
+  __ JumpIfNotSmi(value_reg, &value_is_heap_object);
+  __ JumpIfNotSmi(cell_value_reg, &slow_case);
+  // Old and new values are SMIs, no need for a write barrier here.
+  __ bind(&fast_smi_case);
+  __ Ret(USE_DELAY_SLOT);
+  __ sw(value_reg, FieldMemOperand(cell_reg, PropertyCell::kValueOffset));
+  __ bind(&value_is_heap_object);
+  __ JumpIfSmi(cell_value_reg, &slow_case);
+  Register cell_value_map_reg = cell_value_reg;
+  __ lw(cell_value_map_reg,
+        FieldMemOperand(cell_value_reg, HeapObject::kMapOffset));
+  __ Branch(&fast_heapobject_case, eq, cell_value_map_reg,
+            FieldMemOperand(value_reg, HeapObject::kMapOffset));
+
+  // Fallback to the runtime.
+  __ bind(&slow_case);
+  __ SmiTag(slot_reg);
+  __ Drop(1);  // Pop return address.
+  __ Push(slot_reg, name_reg, value_reg, cell_reg);
+  __ TailCallRuntime(is_strict(language_mode())
+                         ? Runtime::kStoreGlobalViaContext_Strict
+                         : Runtime::kStoreGlobalViaContext_Sloppy,
+                     3, 1);
+}
+
+
 static int AddressOffset(ExternalReference ref0, ExternalReference ref1) {
   return ref0.address() - ref1.address();
 }
 
 
 // Calls an API function.  Allocates HandleScope, extracts returned value
 // from handle and propagates exceptions.  Restores context.  stack_space
 // - space to be unwound on exit (includes the call JS arguments space and
 // the additional space allocated for the fast call).
 static void CallApiFunctionAndReturn(
@@ skipping 289 matching lines @@
                            MemOperand(fp, 6 * kPointerSize), NULL);
 }
 
 
 #undef __
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_TARGET_ARCH_MIPS