Incremental mode now works for x64. The only difference

src/x64/full-codegen-x64.cc

 // Copyright 2011 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 3127 matching lines @@
                                FixedArray::kHeaderSize));
   __ lea(index_2, FieldOperand(elements, index_2, times_pointer_size,
                                FixedArray::kHeaderSize));
 
   // Swap elements.  Use object and temp as scratch registers.
   __ movq(object, Operand(index_1, 0));
   __ movq(temp,   Operand(index_2, 0));
   __ 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.
   __ RememberedSetHelper(
       index_1, temp, kDontSaveFPRegs, MacroAssembler::kFallThroughAtEnd);
   __ 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);
   __ jmp(&done);
 
   __ bind(&slow_case);
   __ CallRuntime(Runtime::kSwapElements, 3);
 
   __ bind(&done);
   context()->Plug(rax);
@@ skipping 1149 matching lines @@
   __ ret(0);
 }
 
 
 #undef __
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_X64