Fix stub frame walking: when materializing the frame content during deoptimization, the stack is no…

runtime/vm/stack_frame.cc

Index: runtime/vm/stack_frame.cc
diff --git a/runtime/vm/stack_frame.cc b/runtime/vm/stack_frame.cc
index 4eb3da7e0d6b94b8b256e9f66d641093e2f3fd6a..3b2b27d9a1fc89ea5da4f1558388917c1f723641 100644
--- a/runtime/vm/stack_frame.cc
+++ b/runtime/vm/stack_frame.cc
@@ -28,7 +28,13 @@ bool StackFrame::IsStubFrame() const {
   NoSafepointScope no_safepoint;
 #endif
   RawCode* code = GetCodeObject();
-  intptr_t cid = code->ptr()->owner_->GetClassId();
+  if (code == Code::null()) {
+    // Frame not yet set up properly (e.g,deoptimization).
+    // This is slow, but rare.
+    const Code& code = Code::Handle(Code::LookupCode(pc()));
+    return code.IsStubCode();

[rmacnak, 2016/03/23 19:44:19]

assert code not null

[srdjan, 2016/03/23 19:48:22]

Done.

+  }
+  const intptr_t cid = code->ptr()->owner_->GetClassId();
   ASSERT(cid == kNullCid || cid == kClassCid || cid == kFunctionCid);
   return cid == kNullCid || cid == kClassCid;
 }