Incremental mode now works for x64. The only difference

src/arm/macro-assembler-arm.cc

Index: src/arm/macro-assembler-arm.cc
===================================================================
--- src/arm/macro-assembler-arm.cc	(revision 8221)
+++ src/arm/macro-assembler-arm.cc	(working copy)
@@ -3166,6 +3166,25 @@
 }
 
 
+void MacroAssembler::IsDataObject(Register value,

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

JumpIfNotDataObject

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

Done.

+                                  Register scratch,
+                                  Label* not_data_object) {

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

Should it have a distance too?

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

No, ARM has fixed width instructions.

+  Label is_data_object;
+  ldr(scratch, FieldMemOperand(value, HeapObject::kMapOffset));
+  CompareRoot(scratch, Heap::kHeapNumberMapRootIndex);
+  b(eq, &is_data_object);
+  ASSERT(kConsStringTag == 1 && kIsConsStringMask == 1);
+  ASSERT(kNotStringTag == 0x80 && kIsNotStringMask == 0x80);
+  // If it's a string and it's not a cons string then it's an object that
+  // doesn't need scanning.
+  ldrb(scratch, FieldMemOperand(scratch, Map::kInstanceTypeOffset));
+  tst(scratch, Operand(kIsConsStringMask | kIsNotStringMask));
+  // Jump if we need to mark it grey and push it.

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

Comment not related to function name or description.

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

Deleted.

+  b(ne, not_data_object);
+  bind(&is_data_object);

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

This detects only HeapNumber and non-cons String.
It seems there are other data objects (Oddballs), but I guess they are
irrelevant because they are always in old-space?
I.e., add comment saying why.

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

Done.

+}
+
+
 void MacroAssembler::GetMarkBits(Register addr_reg,
                                  Register bitmap_reg,
                                  Register mask_reg) {