Incremental mode now works for x64. The only difference

src/x64/full-codegen-x64.cc

Index: src/x64/full-codegen-x64.cc
===================================================================
--- src/x64/full-codegen-x64.cc	(revision 8221)
+++ src/x64/full-codegen-x64.cc	(working copy)
@@ -3145,8 +3145,15 @@
   __ movq(Operand(index_2, 0), object);
   __ movq(Operand(index_1, 0), temp);
 
-  Label new_space;
-  __ InNewSpace(elements, temp, equal, &new_space);
+  Label no_remembered_set;
+  __ CheckPageFlag(elements,
+                   temp,
+                   MemoryChunk::SCAN_ON_SCAVENGE,
+                   not_zero,
+                   &no_remembered_set,
+                   Label::kNear);
+  // Possible optimization: do a check that both values are Smis
+  // (or them and test against Smi mask.)

[Lasse Reichstein, 2011/06/10 13:55:44]

Use JumpIf[Not]BothSmi in X64.

[Erik Corry, 2011/06/10 21:57:29]

JumpIfBothSmi doesn't exist.  I'll do this if I see evidence that it makes any
difference.

 
   // Since we are swapping two objects, the incremental marker is not disturbed,
   // so we don't call the stub that handles this.
@@ -3155,7 +3162,8 @@
   __ RememberedSetHelper(
       index_2, temp, kDontSaveFPRegs, MacroAssembler::kFallThroughAtEnd);
 
-  __ bind(&new_space);
+  __ bind(&no_remembered_set);
+
   // We are done. Drop elements from the stack, and return undefined.
   __ addq(rsp, Immediate(3 * kPointerSize));
   __ LoadRoot(rax, Heap::kUndefinedValueRootIndex);