Merge 'wip/next' into dev

Change-Id: Iff9ee5e23bb326c4371ec8ed81d56f2f05d680e9

1 files changed, 18 insertions, 6 deletions

diff --git a/Source/JavaScriptCore/runtime/StringRecursionChecker.h b/Source/JavaScriptCore/runtime/StringRecursionChecker.h
index 6f236f1f1..0f1990e76 100644
--- a/Source/JavaScriptCore/runtime/StringRecursionChecker.h
+++ b/Source/JavaScriptCore/runtime/StringRecursionChecker.h
@@ -21,7 +21,6 @@
 #define StringRecursionChecker_h
 
 #include "Interpreter.h"
-#include "VMStackBounds.h"
 #include <wtf/StackStats.h>
 #include <wtf/WTFThreadData.h>
 
@@ -51,10 +50,17 @@ private:
 inline JSValue StringRecursionChecker::performCheck()
 {
     VM& vm = m_exec->vm();
-    const VMStackBounds nativeStack(vm, wtfThreadData().stack());
-    if (!nativeStack.isSafeToRecurse())
+    if (!vm.isSafeToRecurse())
         return throwStackOverflowError();
-    bool alreadyVisited = !vm.stringRecursionCheckVisitedObjects.add(m_thisObject).isNewEntry;
+
+    bool alreadyVisited = false;
+    if (!vm.stringRecursionCheckFirstObject)
+        vm.stringRecursionCheckFirstObject = m_thisObject;
+    else if (vm.stringRecursionCheckFirstObject == m_thisObject)
+        alreadyVisited = true;
+    else
+        alreadyVisited = !vm.stringRecursionCheckVisitedObjects.add(m_thisObject).isNewEntry;
+
     if (alreadyVisited)
         return emptyString(); // Return empty string to avoid infinite recursion.
     return JSValue(); // Indicate success.
@@ -76,8 +82,14 @@ inline StringRecursionChecker::~StringRecursionChecker()
 {
     if (m_earlyReturnValue)
         return;
-    ASSERT(m_exec->vm().stringRecursionCheckVisitedObjects.contains(m_thisObject));
-    m_exec->vm().stringRecursionCheckVisitedObjects.remove(m_thisObject);
+
+    VM& vm = m_exec->vm();
+    if (vm.stringRecursionCheckFirstObject == m_thisObject)
+        vm.stringRecursionCheckFirstObject = nullptr;
+    else {
+        ASSERT(vm.stringRecursionCheckVisitedObjects.contains(m_thisObject));
+        vm.stringRecursionCheckVisitedObjects.remove(m_thisObject);
+    }
 }
 
 }