--- old/src/share/vm/opto/output.cpp	2014-03-06 11:59:59.180702046 +0100
+++ new/src/share/vm/opto/output.cpp	2014-03-06 11:59:58.762084924 +0100
@@ -171,8 +171,13 @@
   // Determine if we need to generate a stack overflow check.
   // Do it if the method is not a stub function and
   // has java calls or has frame size > vm_page_size/8.
+  // The debug VM checks that deoptimization doesn't trigger an
+  // unexpected stack overflow (compiled method stack banging should
+  // guarantee it doesn't happen) so we always need the stack bang in
+  // a debug VM.
   return (UseStackBanging && stub_function() == NULL &&
-          (has_java_calls() || frame_size_in_bytes > os::vm_page_size()>>3));
+          (has_java_calls() || frame_size_in_bytes > os::vm_page_size()>>3
+           NOT_DEBUG(|| true)));
 }
 
 bool Compile::need_register_stack_bang() const {