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

runtime/vm/stub_code_ia32.cc

Index: runtime/vm/stub_code_ia32.cc
===================================================================
--- runtime/vm/stub_code_ia32.cc	(revision 22083)
+++ runtime/vm/stub_code_ia32.cc	(working copy)
@@ -959,6 +959,22 @@
   __ pushl(EDX);
   __ pushl(ECX);
 
+  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
+  __ movl(ECX, FieldAddress(EAX, Object::tags_offset()));

[Vyacheslav Egorov (Google), 2013/04/27 19:34:46]

I wonder if doing testl with memory operand before pushing EDX/ECX would save us
something noticeable. (it would save pushing and poping definitely)

[Ivan Posva, 2013/05/03 21:01:37]

Different CL.

+  __ testl(ECX, Immediate(1 << RawObject::kRememberedBit));
+  __ j(EQUAL, &add_to_buffer, Assembler::kNearJump);
+  __ popl(ECX);
+  __ popl(EDX);
+  __ ret();
+
+  __ Bind(&add_to_buffer);
+  __ orl(ECX, Immediate(1 << RawObject::kRememberedBit));
+  __ movl(FieldAddress(EAX, Object::tags_offset()), ECX);
+
   // Load the isolate out of the context.
   // Spilled: EDX, ECX
   // EAX: Address being stored