Fix candidate eviction in code flusher.

This fixes a corner case where a code flushing candidate was evicted
from the candidate list without being revisited by the incremental
marker. An explicit write-barrier makes sure it gets revisited.

R=ulan@chromium.org
BUG=chromium:159140
TEST=cctest/test-heap/Regress159140

Review URL: https://codereview.chromium.org/11451038

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@13153 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/mark-compact.cc

@@ -939,6 +939,10 @@ void CodeFlusher::EvictCandidate(JSFunction* function) {
   ASSERT(!function->next_function_link()->IsUndefined());
   Object* undefined = isolate_->heap()->undefined_value();
 
+  // The function is no longer a candidate, make sure it gets visited
+  // again so that previous flushing decisions are revisited.
+  isolate_->heap()->incremental_marking()->RecordWrites(function);
+
   JSFunction* candidate = jsfunction_candidates_head_;
   JSFunction* next_candidate;
   if (candidate == function) {

test/cctest/test-heap.cc

@@ -2508,3 +2508,63 @@ TEST(Regression144230) {
   USE(global->SetProperty(*name, *call_function, NONE, kNonStrictMode));
   CompileRun("call();");
 }
+
+
+TEST(Regress159140) {
+  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::kNoGCFlags);
+
+  // Prepare several closures that are all eligible for code flushing
+  // because all reachable ones are not optimized. Make sure that the
+  // optimized code object is directly reachable through a handle so
+  // that it is marked black during incremental marking.
+  Handle<Code> code;
+  {
+    HandleScope inner_scope;
+    CompileRun("function h(x) {}"
+               "function mkClosure() {"
+               "  return function(x) { return x + 1; };"
+               "}"
+               "var f = mkClosure();"
+               "var g = mkClosure();"
+               "f(1); f(2);"
+               "g(1); g(2);"
+               "h(1); h(2);"
+               "%OptimizeFunctionOnNextCall(f); f(3);"
+               "%OptimizeFunctionOnNextCall(h); h(3);");
+
+    Handle<JSFunction> f =
+        v8::Utils::OpenHandle(
+            *v8::Handle<v8::Function>::Cast(
+                v8::Context::GetCurrent()->Global()->Get(v8_str("f"))));
+    CHECK(f->is_compiled());
+    CompileRun("f = null;");
+
+    Handle<JSFunction> g =
+        v8::Utils::OpenHandle(
+            *v8::Handle<v8::Function>::Cast(
+                v8::Context::GetCurrent()->Global()->Get(v8_str("g"))));
+    CHECK(g->is_compiled());
+    const int kAgingThreshold = 6;
+    for (int i = 0; i < kAgingThreshold; i++) {
+      g->code()->MakeOlder(static_cast<MarkingParity>(i % 2));
+    }
+
+    code = inner_scope.CloseAndEscape(Handle<Code>(f->code()));
+  }
+
+  // Simulate incremental marking so that the functions are enqueued as
+  // code flushing candidates. Then optimize one function. Finally
+  // finish the GC to complete code flushing.
+  SimulateIncrementalMarking();
+  CompileRun("%OptimizeFunctionOnNextCall(g); g(3);");
+  HEAP->CollectAllGarbage(Heap::kNoGCFlags);
+
+  // Unoptimized code is missing and the deoptimizer will go ballistic.
+  CompileRun("g('bozo');");
+}