Improve write barriers in optimized code.

src/x64/macro-assembler-x64.h

 // 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.
 
 #ifndef V8_X64_MACRO_ASSEMBLER_X64_H_
 #define V8_X64_MACRO_ASSEMBLER_X64_H_
 
 #include "src/assembler.h"
 #include "src/frames.h"
 #include "src/globals.h"
@@ skipping 11 matching lines @@
 const int kSmiConstantRegisterValue = 1;
 // Actual value of root register is offset from the root array's start
 // to take advantage of negitive 8-bit displacement values.
 const int kRootRegisterBias = 128;
 
 // Convenience for platform-independent signatures.
 typedef Operand MemOperand;
 
 enum RememberedSetAction { EMIT_REMEMBERED_SET, OMIT_REMEMBERED_SET };
 enum SmiCheck { INLINE_SMI_CHECK, OMIT_SMI_CHECK };
+enum PointersToHereCheck {
+  kPointersToHereMaybeInteresting,
+  kPointersToHereAreAlwaysInteresting
+};
 
 enum SmiOperationConstraint {
   PRESERVE_SOURCE_REGISTER,
   BAILOUT_ON_NO_OVERFLOW,
   BAILOUT_ON_OVERFLOW,
   NUMBER_OF_CONSTRAINTS
 };
 
 STATIC_ASSERT(NUMBER_OF_CONSTRAINTS <= 8);
 
@@ skipping 171 matching lines @@
   // stored.  value and scratch registers are clobbered by the operation.
   // The offset is the offset from the start of the object, not the offset from
   // the tagged HeapObject pointer.  For use with FieldOperand(reg, off).
   void RecordWriteField(
       Register object,
       int offset,
       Register value,
       Register scratch,
       SaveFPRegsMode save_fp,
       RememberedSetAction remembered_set_action = EMIT_REMEMBERED_SET,
-      SmiCheck smi_check = INLINE_SMI_CHECK);
+      SmiCheck smi_check = INLINE_SMI_CHECK,
+      PointersToHereCheck pointers_to_here_check_for_value =
+          kPointersToHereMaybeInteresting);
 
   // As above, but the offset has the tag presubtracted.  For use with
   // Operand(reg, off).
   void RecordWriteContextSlot(
       Register context,
       int offset,
       Register value,
       Register scratch,
       SaveFPRegsMode save_fp,
       RememberedSetAction remembered_set_action = EMIT_REMEMBERED_SET,
-      SmiCheck smi_check = INLINE_SMI_CHECK) {
+      SmiCheck smi_check = INLINE_SMI_CHECK,
+      PointersToHereCheck pointers_to_here_check_for_value =
+          kPointersToHereMaybeInteresting) {
     RecordWriteField(context,
                      offset + kHeapObjectTag,
                      value,
                      scratch,
                      save_fp,
                      remembered_set_action,
-                     smi_check);
+                     smi_check,
+                     pointers_to_here_check_for_value);
   }
 
   // Notify the garbage collector that we wrote a pointer into a fixed array.
   // |array| is the array being stored into, |value| is the
   // object being stored.  |index| is the array index represented as a non-smi.
   // All registers are clobbered by the operation RecordWriteArray
   // filters out smis so it does not update the write barrier if the
   // value is a smi.
   void RecordWriteArray(
       Register array,
       Register value,
       Register index,
       SaveFPRegsMode save_fp,
       RememberedSetAction remembered_set_action = EMIT_REMEMBERED_SET,
-      SmiCheck smi_check = INLINE_SMI_CHECK);
+      SmiCheck smi_check = INLINE_SMI_CHECK,
+      PointersToHereCheck pointers_to_here_check_for_value =
+          kPointersToHereMaybeInteresting);
+
+  void RecordWriteForMap(
+      Register object,
+      Register map,
+      Register dst,
+      SaveFPRegsMode save_fp);
 
   // For page containing |object| mark region covering |address|
   // dirty. |object| is the object being stored into, |value| is the
   // object being stored. The address and value registers are clobbered by the
   // operation.  RecordWrite filters out smis so it does not update
   // the write barrier if the value is a smi.
   void RecordWrite(
       Register object,
       Register address,
       Register value,
       SaveFPRegsMode save_fp,
       RememberedSetAction remembered_set_action = EMIT_REMEMBERED_SET,
-      SmiCheck smi_check = INLINE_SMI_CHECK);
+      SmiCheck smi_check = INLINE_SMI_CHECK,
+      PointersToHereCheck pointers_to_here_check_for_value =
+          kPointersToHereMaybeInteresting);
 
   // ---------------------------------------------------------------------------
   // Debugger Support
 
   void DebugBreak();
 
   // Generates function and stub prologue code.
   void StubPrologue();
   void Prologue(bool code_pre_aging);
 
@@ skipping 1317 matching lines @@
     masm->popfq();                                                           \
   }                                                                          \
   masm->
 #else
 #define ACCESS_MASM(masm) masm->
 #endif
 
 } }  // namespace v8::internal
 
 #endif  // V8_X64_MACRO_ASSEMBLER_X64_H_