1 files changed, 113 insertions, 0 deletions
diff --git a/Source/JavaScriptCore/runtime/ThrowScope.cpp b/Source/JavaScriptCore/runtime/ThrowScope.cpp
new file mode 100644
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+++ b/Source/JavaScriptCore/runtime/ThrowScope.cpp
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+/*
+ * Copyright (C) 2016 Apple Inc. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. 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 with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
+ * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+ * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE INC. OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+ * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+ * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+ * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
+ * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "config.h"
+#include "ThrowScope.h"
+
+#include "Exception.h"
+#include "JSCInlines.h"
+#include "VM.h"
+
+namespace JSC {
+    
+#if ENABLE(EXCEPTION_SCOPE_VERIFICATION)
+
+ThrowScope::ThrowScope(VM& vm, ExceptionEventLocation location)
+    : ExceptionScope(vm, location)
+{
+    m_vm.verifyExceptionCheckNeedIsSatisfied(m_recursionDepth, m_location);
+}
+
+ThrowScope::~ThrowScope()
+{
+    RELEASE_ASSERT(m_vm.m_topExceptionScope);
+
+    if (!m_isReleased)
+        m_vm.verifyExceptionCheckNeedIsSatisfied(m_recursionDepth, m_location);
+    else {
+        // If we released the scope, that means we're letting our callers do the
+        // exception check. However, because our caller may be a LLInt or JIT
+        // function (which always checks for exceptions but won't clear the
+        // m_needExceptionCheck bit), we should clear m_needExceptionCheck here
+        // and let code below decide if we need to simulate a re-throw.
+        m_vm.m_needExceptionCheck = false;
+    }
+
+    bool willBeHandleByLLIntOrJIT = false;
+    void* previousScope = m_previousScope;
+    void* topVMEntryFrame = m_vm.topVMEntryFrame;
+
+    // If the topVMEntryFrame was pushed on the stack after the previousScope was instantiated,
+    // then this throwScope will be returning to LLINT or JIT code that always do an exception
+    // check. In that case, skip the simulated throw because the LLInt and JIT will be
+    // checking for the exception their own way instead of calling ThrowScope::exception().
+    if (topVMEntryFrame && previousScope > topVMEntryFrame)
+        willBeHandleByLLIntOrJIT = true;
+    
+    if (!willBeHandleByLLIntOrJIT)
+        simulateThrow();
+}
+
+void ThrowScope::throwException(ExecState* exec, Exception* exception)
+{
+    if (m_vm.exception() && m_vm.exception() != exception)
+        m_vm.verifyExceptionCheckNeedIsSatisfied(m_recursionDepth, m_location);
+    
+    m_vm.throwException(exec, exception);
+}
+
+JSValue ThrowScope::throwException(ExecState* exec, JSValue error)
+{
+    if (!error.isCell() || !jsDynamicCast<Exception*>(m_vm, error.asCell()))
+        m_vm.verifyExceptionCheckNeedIsSatisfied(m_recursionDepth, m_location);
+    
+    return m_vm.throwException(exec, error);
+}
+
+JSObject* ThrowScope::throwException(ExecState* exec, JSObject* obj)
+{
+    if (!jsDynamicCast<Exception*>(m_vm, obj))
+        m_vm.verifyExceptionCheckNeedIsSatisfied(m_recursionDepth, m_location);
+    
+    return m_vm.throwException(exec, obj);
+}
+
+void ThrowScope::simulateThrow()
+{
+    RELEASE_ASSERT(m_vm.m_topExceptionScope);
+    m_vm.m_simulatedThrowPointLocation = m_location;
+    m_vm.m_simulatedThrowPointRecursionDepth = m_recursionDepth;
+    m_vm.m_needExceptionCheck = true;
+
+    if (Options::dumpSimulatedThrows()) {
+        dataLog("Simulated throw from this scope: ", m_location, "\n");
+        dataLog("    (ExceptionScope::m_recursionDepth was ", m_recursionDepth, ")\n");
+        WTFReportBacktrace();
+    }
+}
+
+#endif // ENABLE(EXCEPTION_SCOPE_VERIFICATION)
+    
+} // namespace JSC