Revert "Remove Code::active_instructions_."

runtime/vm/raw_object.cc

Index: runtime/vm/raw_object.cc
diff --git a/runtime/vm/raw_object.cc b/runtime/vm/raw_object.cc
index 3e3d0f470dffa13a8ba9bb46f76a6614b8887672..d32b5abf8771f8d5bc1f9cb28092409c0f17534c 100644
--- a/runtime/vm/raw_object.cc
+++ b/runtime/vm/raw_object.cc
@@ -542,11 +542,8 @@ intptr_t RawCode::VisitCodePointers(RawCode* raw_obj,
 
   RawCode* obj = raw_obj->ptr();
   intptr_t length = Code::PtrOffBits::decode(obj->state_bits_);
-#if defined(TARGET_ARCH_IA32)
-  // On IA32 only we embed pointers to objects directly in the generated
-  // instructions. The variable porition of a Code object describes where to
-  // find those pointers for tracing.
   if (Code::AliveBit::decode(obj->state_bits_)) {
+    // Also visit all the embedded pointers in the corresponding instructions.
     uword entry_point = reinterpret_cast<uword>(obj->instructions_->ptr()) +
         Instructions::HeaderSize();
     for (intptr_t i = 0; i < length; i++) {
@@ -556,12 +553,6 @@ intptr_t RawCode::VisitCodePointers(RawCode* raw_obj,
     }
   }
   return Code::InstanceSize(length);
-#else
-  // On all other architectures, objects are referenced indirectly through
-  // either the ObjectPool or Thread.
-  ASSERT(length == 0);
-  return Code::InstanceSize(0);
-#endif
 }