Fix shared function info code replacement.

test/cctest/test-heap.cc

Index: test/cctest/test-heap.cc
diff --git a/test/cctest/test-heap.cc b/test/cctest/test-heap.cc
index 4ca1a68f4bfa9a83c4806538a0a4a678cf09b336..eb9ebb721eef4ac3287c942842c9038744ba4c4a 100644
--- a/test/cctest/test-heap.cc
+++ b/test/cctest/test-heap.cc
@@ -2627,3 +2627,72 @@ TEST(Regress165495) {
   // Unoptimized code is missing and the deoptimizer will go ballistic.
   CompileRun("var g = mkClosure(); g('bozo');");
 }
+
+
+TEST(Regress169209) {
+  i::FLAG_allow_natives_syntax = true;
+  i::FLAG_flush_code_incrementally = true;
+  InitializeVM();
+  v8::HandleScope scope;
+
+  // Perform one initial GC to enable code flushing.
+  HEAP->CollectAllGarbage(Heap::kAbortIncrementalMarkingMask);
+
+  // Prepare a shared function info eligible for code flushing for which
+  // the unoptimized code will be replaced during optimization.
+  Handle<SharedFunctionInfo> shared1;
+  {
+    HandleScope inner_scope;
+    CompileRun("function f() { return 'foobar'; }"
+               "function g(x) { if (x) f(); }"
+               "f();"
+               "g(false);"
+               "g(false);");
+
+    Handle<JSFunction> f =
+        v8::Utils::OpenHandle(
+            *v8::Handle<v8::Function>::Cast(
+                v8::Context::GetCurrent()->Global()->Get(v8_str("f"))));
+    CHECK(f->is_compiled());
+    const int kAgingThreshold = 6;
+    for (int i = 0; i < kAgingThreshold; i++) {
+      f->shared()->code()->MakeOlder(static_cast<MarkingParity>(i % 2));
+    }
+
+    shared1 = inner_scope.CloseAndEscape(handle(f->shared(), ISOLATE));
+  }
+
+  // Prepare a shared function info eligible for code flushing that will
+  // represent the dangling tail of the candidate list.
+  Handle<SharedFunctionInfo> shared2;
+  {
+    HandleScope inner_scope;
+    CompileRun("function flushMe() { return 0; }"
+               "flushMe(1);");
+
+    Handle<JSFunction> f =
+        v8::Utils::OpenHandle(
+            *v8::Handle<v8::Function>::Cast(
+                v8::Context::GetCurrent()->Global()->Get(v8_str("flushMe"))));
+    CHECK(f->is_compiled());
+    const int kAgingThreshold = 6;
+    for (int i = 0; i < kAgingThreshold; i++) {
+      f->shared()->code()->MakeOlder(static_cast<MarkingParity>(i % 2));
+    }
+
+    shared2 = inner_scope.CloseAndEscape(handle(f->shared(), ISOLATE));
+  }
+
+  // Simulate incremental marking and collect code flushing candidates.
+  SimulateIncrementalMarking();
+  CHECK(shared1->code()->gc_metadata() != NULL);
+
+  // Optimize function and make sure the unoptimized code is replaced.
+  FLAG_stop_at = "f";
+  CompileRun("%OptimizeFunctionOnNextCall(g);"
+             "g(false);");
+
+  // Finish garbage collection cycle.
+  HEAP->CollectAllGarbage(Heap::kNoGCFlags);
+  CHECK(shared1->code()->gc_metadata() == NULL);
+}