Fix issue 493: Infinite loop when debug break is set when entering function.apply

src/execution.h

 // Copyright 2006-2008 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 132 matching lines @@
 
 // StackGuard contains the handling of the limits that are used to limit the
 // number of nested invocations of JavaScript and the stack size used in each
 // invocation.
 class StackGuard : public AllStatic {
  public:
   // Pass the address beyond which the stack should not grow.  The stack
   // is assumed to grow downwards.
   static void SetStackLimit(uintptr_t limit);
 
-  static Address address_of_jslimit() {
-    return reinterpret_cast<Address>(&thread_local_.jslimit_);
-  }
-
   // Threading support.
   static char* ArchiveStackGuard(char* to);
   static char* RestoreStackGuard(char* from);
   static int ArchiveSpacePerThread();
   static void FreeThreadResources();
   // Sets up the default stack guard for this thread if it has not
   // already been set up.
   static void InitThread(const ExecutionAccess& lock);
   // Clears the stack guard for this thread so it does not look as if
   // it has been set up.
   static void ClearThread(const ExecutionAccess& lock);
 
   static bool IsStackOverflow();
   static bool IsPreempted();
   static void Preempt();
   static bool IsInterrupted();
   static void Interrupt();
   static bool IsTerminateExecution();
   static void TerminateExecution();
 #ifdef ENABLE_DEBUGGER_SUPPORT
   static bool IsDebugBreak();
   static void DebugBreak();
   static bool IsDebugCommand();
   static void DebugCommand();
 #endif
   static void Continue(InterruptFlag after_what);
 
-  // This provides an asynchronous read of the stack limit for the current
+  // This provides an asynchronous read of the stack limits for the current
   // thread.  There are no locks protecting this, but it is assumed that you
   // have the global V8 lock if you are using multiple V8 threads.
   static uintptr_t climit() {
     return thread_local_.climit_;
   }
-
   static uintptr_t jslimit() {
     return thread_local_.jslimit_;
   }
+  static uintptr_t real_jslimit() {
+    return thread_local_.real_jslimit_;
+  }
+  static Address address_of_jslimit() {
+    return reinterpret_cast<Address>(&thread_local_.jslimit_);
+  }
+  static Address address_of_real_jslimit() {
+    return reinterpret_cast<Address>(&thread_local_.real_jslimit_);
+  }
 
  private:
   // You should hold the ExecutionAccess lock when calling this method.
   static bool IsSet(const ExecutionAccess& lock);
 
   // You should hold the ExecutionAccess lock when calling this method.
   static void set_limits(uintptr_t value, const ExecutionAccess& lock) {
-    Heap::SetStackLimit(value);
     thread_local_.jslimit_ = value;
     thread_local_.climit_ = value;
+    Heap::SetStackLimits();
   }
 
-  // Reset limits to initial values. For example after handling interrupt.
+  // Reset limits to actual values. For example after handling interrupt.
   // You should hold the ExecutionAccess lock when calling this method.
   static void reset_limits(const ExecutionAccess& lock) {
-    thread_local_.jslimit_ = thread_local_.initial_jslimit_;
-    Heap::SetStackLimit(thread_local_.jslimit_);
-    thread_local_.climit_ = thread_local_.initial_climit_;
+    thread_local_.jslimit_ = thread_local_.real_jslimit_;
+    thread_local_.climit_ = thread_local_.real_climit_;
+    Heap::SetStackLimits();
   }
 
   // Enable or disable interrupts.
   static void EnableInterrupts();
   static void DisableInterrupts();
 
   static const uintptr_t kLimitSize = kPointerSize * 128 * KB;
 
 #ifdef V8_TARGET_ARCH_X64
   static const uintptr_t kInterruptLimit = V8_UINT64_C(0xfffffffffffffffe);
   static const uintptr_t kIllegalLimit = V8_UINT64_C(0xfffffffffffffff8);
 #else
   static const uintptr_t kInterruptLimit = 0xfffffffe;
   static const uintptr_t kIllegalLimit = 0xfffffff8;
 #endif
 
   class ThreadLocal {
    public:
     ThreadLocal() { Clear(); }
     // You should hold the ExecutionAccess lock when you call Initialize or
     // Clear.
     void Initialize();
     void Clear();
-    uintptr_t initial_jslimit_;
+
+    // The stack limit is split into a JavaScript and a C++ stack limit. These
+    // two are the same except when running on a simulator where the C++ and
+    // JavaScript stacks are separate. Each of the two stack limits have two
+    // values. The one eith the real_ prefix is the actual stack limit
+    // set for the VM. The one without the real_ prefix has the same value as
+    // the actual stack limit except when there is an interruption (e.g. debug
+    // break or preemption) in which case it is lowered to make stack checks
+    // fail. Both the generated code and the runtime system check against the
+    // one without the real_ prefix.
+    uintptr_t real_jslimit_;  // Actual JavaScript stack limit set for the VM.
     uintptr_t jslimit_;
-    uintptr_t initial_climit_;
+    uintptr_t real_climit_;  // Actual C++ stack limit set for the VM.
     uintptr_t climit_;
+
     int nesting_;
     int postpone_interrupts_nesting_;
     int interrupt_flags_;
   };
 
   static ThreadLocal thread_local_;
 
   friend class StackLimitCheck;
   friend class PostponeInterruptsScope;
 };
@@ skipping 39 matching lines @@
       v8::Handle<v8::String> name);
   static v8::Handle<v8::Value> GC(const v8::Arguments& args);
  private:
   static const char* kSource;
 };
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_EXECUTION_H_