CallIC customization stubs must accept that a vector slot is cleared.

test/mjsunit/regress/regress-392114.js

-// Copyright 2013 the V8 project authors. All rights reserved.
+// Copyright 2014 the V8 project authors. All rights reserved.
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 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 // Flags: --expose-debug-as debug --allow-natives-syntax
 
 Debug = debug.Debug;
-var listened = false;
 
-function listener(event, exec_state, event_data, data) {
-  if (event == Debug.DebugEvent.Exception) {
-    for (var i = 0; i < exec_state.frameCount(); i++) {
-      print(exec_state.frame(i).receiver());
-      print(exec_state.frame(i).func().name());
+function dummy(x) {
+  return x + 100;
+}
+
+function create_closure() {
+  return function(arg) {
+    if (arg === true) {

[Toon Verwaest, 2014/07/29 11:28:18]

if (arg) { %DeoptimizeFunction(function); }

+      // Do something that causes a deopt. We'd like to run the newly compiled
+      // full code for the Array statement below. Soft deopt:
+      dummy();
+    }
+    var a = Array(10);
+    for (var i = 0; i < a.length; i++) {
+      a[i] = i;
     }
   }
-  listened = true;
 }
 
-Debug.setListener(listener);
-Debug.setBreakOnException();
+var c = create_closure();
+c();
 
-assertThrows(function() { delete null['foo']; });
+// c CallIC state now has custom Array handler installed.
 
-Debug.clearBreakOnException();
-Debug.setListener(null);
+// Turn on the debugger.
+Debug.setListener(function () {});
 
-assertTrue(listened);
+var d = create_closure();
+%OptimizeFunctionOnNextCall(d);
+// Thanks to the debugger, we recreate the full code too. We deopt and run
+// it, stomping on the unexpected AllocationSite in the type vector slot.
+d(true);
+
+// CallIC in c misinterprets type vector slot contents as an AllocationSite,
+// corrupting the heap.
+c();
+
+// CallIC MISS - crash due to corruption.
+dummy();