- Remember the fact that an object has been added to the

runtime/vm/stub_code_arm.cc

Index: runtime/vm/stub_code_arm.cc
===================================================================
--- runtime/vm/stub_code_arm.cc	(revision 22083)
+++ runtime/vm/stub_code_arm.cc	(working copy)
@@ -876,6 +876,21 @@
   // Save values being destroyed.
   __ PushList((1 << R1) | (1 << R2) | (1 << R3));
 
+  Label add_to_buffer;
+  // Check whether this object has already been remembered. Skip adding to the
+  // store buffer if the object is in the store buffer already.
+  // Spilled: EDX, ECX
+  // EAX: Address being stored
+  __ ldr(R2, FieldAddress(R0, Object::tags_offset()));
+  __ tst(R2, ShifterOperand(1 << RawObject::kRememberedBit));
+  __ b(&add_to_buffer, EQ);
+  __ PopList((1 << R1) | (1 << R2) | (1 << R3));
+  __ Ret();
+
+  __ Bind(&add_to_buffer);
+  __ orr(R2, R2, ShifterOperand(1 << RawObject::kRememberedBit));
+  __ str(R2, FieldAddress(R0, Object::tags_offset()));
+
   // Load the isolate out of the context.
   // Spilled: R1, R2, R3.
   // R0: address being stored.