The way reloc entries are visited by the ObjectVisitor is architecture...

src/arm/assembler-arm-inl.h

Index: src/arm/assembler-arm-inl.h
===================================================================
--- src/arm/assembler-arm-inl.h	(revision 4713)
+++ src/arm/assembler-arm-inl.h	(working copy)
@@ -39,6 +39,7 @@
 
 #include "arm/assembler-arm.h"
 #include "cpu.h"
+#include "debug.h"
 
 
 namespace v8 {
@@ -73,6 +74,11 @@
 }
 
 
+int RelocInfo::target_address_size() {
+  return Assembler::kExternalTargetSize;
+}
+
+
 void RelocInfo::set_target_address(Address target) {
   ASSERT(IsCodeTarget(rmode_) || rmode_ == RUNTIME_ENTRY);
   Assembler::set_target_address_at(pc_, target);
@@ -162,6 +168,26 @@
 }
 
 
+void RelocInfo::Visit(ObjectVisitor* visitor) {
+  RelocInfo::Mode mode = rmode();
+  if (mode == RelocInfo::EMBEDDED_OBJECT) {
+    visitor->VisitPointer(target_object_address());
+  } else if (RelocInfo::IsCodeTarget(mode)) {
+    visitor->VisitCodeTarget(this);
+  } else if (mode == RelocInfo::EXTERNAL_REFERENCE) {
+    visitor->VisitExternalReference(target_reference_address());
+#ifdef ENABLE_DEBUGGER_SUPPORT
+  } else if (Debug::has_break_points() &&
+             RelocInfo::IsJSReturn(mode) &&
+             IsPatchedReturnSequence()) {
+    visitor->VisitDebugTarget(this);
+#endif
+  } else if (mode == RelocInfo::RUNTIME_ENTRY) {
+    visitor->VisitRuntimeEntry(this);
+  }
+}
+
+
 Operand::Operand(int32_t immediate, RelocInfo::Mode rmode)  {
   rm_ = no_reg;
   imm32_ = immediate;