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diff --git a/deps/v8/src/execution/stack-guard.h b/deps/v8/src/execution/stack-guard.h
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+++ b/deps/v8/src/execution/stack-guard.h
@@ -0,0 +1,186 @@
+// Copyright 2019 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef V8_EXECUTION_STACK_GUARD_H_
+#define V8_EXECUTION_STACK_GUARD_H_
+
+#include "include/v8-internal.h"
+#include "src/base/atomicops.h"
+
+namespace v8 {
+namespace internal {
+
+class ExecutionAccess;
+class InterruptsScope;
+class Isolate;
+class Object;
+
+// 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 V8_EXPORT_PRIVATE StackGuard final {
+ public:
+  explicit StackGuard(Isolate* isolate) : isolate_(isolate) {}
+
+  // Pass the address beyond which the stack should not grow.  The stack
+  // is assumed to grow downwards.
+  void SetStackLimit(uintptr_t limit);
+
+  // The simulator uses a separate JS stack. Limits on the JS stack might have
+  // to be adjusted in order to reflect overflows of the C stack, because we
+  // cannot rely on the interleaving of frames on the simulator.
+  void AdjustStackLimitForSimulator();
+
+  // Threading support.
+  char* ArchiveStackGuard(char* to);
+  char* RestoreStackGuard(char* from);
+  static int ArchiveSpacePerThread() { return sizeof(ThreadLocal); }
+  void FreeThreadResources();
+  // Sets up the default stack guard for this thread if it has not
+  // already been set up.
+  void InitThread(const ExecutionAccess& lock);
+  // Clears the stack guard for this thread so it does not look as if
+  // it has been set up.
+  void ClearThread(const ExecutionAccess& lock);
+
+#define INTERRUPT_LIST(V)                                         \
+  V(TERMINATE_EXECUTION, TerminateExecution, 0)                   \
+  V(GC_REQUEST, GC, 1)                                            \
+  V(INSTALL_CODE, InstallCode, 2)                                 \
+  V(API_INTERRUPT, ApiInterrupt, 3)                               \
+  V(DEOPT_MARKED_ALLOCATION_SITES, DeoptMarkedAllocationSites, 4) \
+  V(GROW_SHARED_MEMORY, GrowSharedMemory, 5)                      \
+  V(LOG_WASM_CODE, LogWasmCode, 6)                                \
+  V(WASM_CODE_GC, WasmCodeGC, 7)
+
+#define V(NAME, Name, id)                                    \
+  inline bool Check##Name() { return CheckInterrupt(NAME); } \
+  inline void Request##Name() { RequestInterrupt(NAME); }    \
+  inline void Clear##Name() { ClearInterrupt(NAME); }
+  INTERRUPT_LIST(V)
+#undef V
+
+  // Flag used to set the interrupt causes.
+  enum InterruptFlag {
+#define V(NAME, Name, id) NAME = (1 << id),
+    INTERRUPT_LIST(V)
+#undef V
+#define V(NAME, Name, id) NAME |
+        ALL_INTERRUPTS = INTERRUPT_LIST(V) 0
+#undef V
+  };
+
+  uintptr_t climit() { return thread_local_.climit(); }
+  uintptr_t jslimit() { return thread_local_.jslimit(); }
+  // 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.
+  uintptr_t real_climit() { return thread_local_.real_climit_; }
+  uintptr_t real_jslimit() { return thread_local_.real_jslimit_; }
+  Address address_of_jslimit() {
+    return reinterpret_cast<Address>(&thread_local_.jslimit_);
+  }
+  Address address_of_real_jslimit() {
+    return reinterpret_cast<Address>(&thread_local_.real_jslimit_);
+  }
+
+  // If the stack guard is triggered, but it is not an actual
+  // stack overflow, then handle the interruption accordingly.
+  Object HandleInterrupts();
+
+ private:
+  bool CheckInterrupt(InterruptFlag flag);
+  void RequestInterrupt(InterruptFlag flag);
+  void ClearInterrupt(InterruptFlag flag);
+  int FetchAndClearInterrupts();
+
+  // You should hold the ExecutionAccess lock when calling this method.
+  bool has_pending_interrupts(const ExecutionAccess& lock) {
+    return thread_local_.interrupt_flags_ != 0;
+  }
+
+  // You should hold the ExecutionAccess lock when calling this method.
+  inline void set_interrupt_limits(const ExecutionAccess& lock);
+
+  // Reset limits to actual values. For example after handling interrupt.
+  // You should hold the ExecutionAccess lock when calling this method.
+  inline void reset_limits(const ExecutionAccess& lock);
+
+  // Enable or disable interrupts.
+  void EnableInterrupts();
+  void DisableInterrupts();
+
+#if V8_TARGET_ARCH_64_BIT
+  static const uintptr_t kInterruptLimit = uintptr_t{0xfffffffffffffffe};
+  static const uintptr_t kIllegalLimit = uintptr_t{0xfffffffffffffff8};
+#else
+  static const uintptr_t kInterruptLimit = 0xfffffffe;
+  static const uintptr_t kIllegalLimit = 0xfffffff8;
+#endif
+
+  void PushInterruptsScope(InterruptsScope* scope);
+  void PopInterruptsScope();
+
+  class ThreadLocal final {
+   public:
+    ThreadLocal() { Clear(); }
+    // You should hold the ExecutionAccess lock when you call Initialize or
+    // Clear.
+    void Clear();
+
+    // Returns true if the heap's stack limits should be set, false if not.
+    bool Initialize(Isolate* isolate);
+
+    // 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 real_climit_;   // Actual C++ stack limit set for the VM.
+
+    // jslimit_ and climit_ can be read without any lock.
+    // Writing requires the ExecutionAccess lock.
+    base::AtomicWord jslimit_;
+    base::AtomicWord climit_;
+
+    uintptr_t jslimit() {
+      return bit_cast<uintptr_t>(base::Relaxed_Load(&jslimit_));
+    }
+    void set_jslimit(uintptr_t limit) {
+      return base::Relaxed_Store(&jslimit_,
+                                 static_cast<base::AtomicWord>(limit));
+    }
+    uintptr_t climit() {
+      return bit_cast<uintptr_t>(base::Relaxed_Load(&climit_));
+    }
+    void set_climit(uintptr_t limit) {
+      return base::Relaxed_Store(&climit_,
+                                 static_cast<base::AtomicWord>(limit));
+    }
+
+    InterruptsScope* interrupt_scopes_;
+    int interrupt_flags_;
+  };
+
+  // TODO(isolates): Technically this could be calculated directly from a
+  //                 pointer to StackGuard.
+  Isolate* isolate_;
+  ThreadLocal thread_local_;
+
+  friend class Isolate;
+  friend class StackLimitCheck;
+  friend class InterruptsScope;
+
+  DISALLOW_COPY_AND_ASSIGN(StackGuard);
+};
+
+}  // namespace internal
+}  // namespace v8
+
+#endif  // V8_EXECUTION_STACK_GUARD_H_