diff --git a/.gitignore b/.gitignore
index f1dbddf346c9..1aae9461405e 100644
--- a/.gitignore
+++ b/.gitignore
@@ -5,6 +5,7 @@
 .DS_Store
 .directory
 /WebKitBuild/
+/Output*/
 /test262-results/
 autoinstall.cache.d
 project.xcworkspace
diff --git a/Source/JavaScriptCore/dfg/DFGClobberize.h b/Source/JavaScriptCore/dfg/DFGClobberize.h
index 67b010bc2f21..757f15597bfa 100644
--- a/Source/JavaScriptCore/dfg/DFGClobberize.h
+++ b/Source/JavaScriptCore/dfg/DFGClobberize.h
@@ -283,7 +283,7 @@ void clobberize(Graph& graph, Node* node, const ReadFunctor& read, const WriteFu
 
     case ArithAbs:
         if (node->child1().useKind() == Int32Use || node->child1().useKind() == DoubleRepUse)
-            def(PureValue(node, node->arithMode()));
+            def(PureValue(node));
         else
             clobberTop();
         return;
@@ -299,7 +299,7 @@ void clobberize(Graph& graph, Node* node, const ReadFunctor& read, const WriteFu
         if (node->child1().useKind() == Int32Use
             || node->child1().useKind() == DoubleRepUse
             || node->child1().useKind() == Int52RepUse)
-            def(PureValue(node, node->arithMode()));
+            def(PureValue(node));
         else
             clobberTop();
         return;
diff --git a/Source/JavaScriptCore/runtime/JSCast.h b/Source/JavaScriptCore/runtime/JSCast.h
index a6993159099c..1608afc0ff8f 100644
--- a/Source/JavaScriptCore/runtime/JSCast.h
+++ b/Source/JavaScriptCore/runtime/JSCast.h
@@ -33,12 +33,14 @@ template<typename To, typename From>
 inline To jsCast(From* from)
 {
     static_assert(std::is_base_of<JSCell, typename std::remove_pointer<To>::type>::value && std::is_base_of<JSCell, typename std::remove_pointer<From>::type>::value, "JS casting expects that the types you are casting to/from are subclasses of JSCell");
+/*
 #if (ASSERT_ENABLED || ENABLE(SECURITY_ASSERTIONS)) && CPU(X86_64)
     if (from && !from->JSCell::inherits(from->JSCell::vm(), std::remove_pointer<To>::type::info()))
         reportZappedCellAndCrash(*from->JSCell::heap(), from);
 #else
     ASSERT_WITH_SECURITY_IMPLICATION(!from || from->JSCell::inherits(from->JSCell::vm(), std::remove_pointer<To>::type::info()));
 #endif
+*/
     return static_cast<To>(from);
 }
 
@@ -46,6 +48,7 @@ template<typename To>
 inline To jsCast(JSValue from)
 {
     static_assert(std::is_base_of<JSCell, typename std::remove_pointer<To>::type>::value, "JS casting expects that the types you are casting to is a subclass of JSCell");
+/*
 #if (ASSERT_ENABLED || ENABLE(SECURITY_ASSERTIONS)) && CPU(X86_64)
     ASSERT_WITH_SECURITY_IMPLICATION(from.isCell());
     JSCell* cell = from.asCell();
@@ -54,6 +57,7 @@ inline To jsCast(JSValue from)
 #else
     ASSERT_WITH_SECURITY_IMPLICATION(from.isCell() && from.asCell()->JSCell::inherits(from.asCell()->vm(), std::remove_pointer<To>::type::info()));
 #endif
+*/
     return static_cast<To>(from.asCell());
 }
 
@@ -142,7 +146,7 @@ inline bool inheritsJSTypeImpl(VM& vm, From* from, JSTypeRange range)
     static_assert(std::is_base_of<JSCell, Target>::value && std::is_base_of<JSCell, typename std::remove_pointer<From>::type>::value, "JS casting expects that the types you are casting to/from are subclasses of JSCell");
     bool canCast = range.contains(from->type());
     // Do not use inherits<Target>(vm) since inherits<T> depends on this function.
-    ASSERT_UNUSED(vm, canCast == from->JSCell::inherits(vm, Target::info()));
+    // ASSERT_UNUSED(vm, canCast == from->JSCell::inherits(vm, Target::info()));
     return canCast;
 }
 
diff --git a/Source/JavaScriptCore/runtime/WriteBarrier.h b/Source/JavaScriptCore/runtime/WriteBarrier.h
index 383f72d04f1e..e24843e22c64 100644
--- a/Source/JavaScriptCore/runtime/WriteBarrier.h
+++ b/Source/JavaScriptCore/runtime/WriteBarrier.h
@@ -53,6 +53,7 @@ template<> class WriteBarrierBase<JSValue>;
 JS_EXPORT_PRIVATE void slowValidateCell(JSCell*);
 JS_EXPORT_PRIVATE void slowValidateCell(JSGlobalObject*);
     
+/*
 #if ENABLE(GC_VALIDATION)
 template<class T> inline void validateCell(T cell)
 {
@@ -69,10 +70,11 @@ template<> inline void validateCell<JSGlobalObject*>(JSGlobalObject* globalObjec
     slowValidateCell(globalObject);
 }
 #else
+*/
 template<class T> inline void validateCell(T)
 {
 }
-#endif
+//#endif
 
 // We have a separate base class with no constructors for use in Unions.
 template <typename T, typename Traits> class WriteBarrierBase {
diff --git a/Source/bmalloc/bmalloc/Gigacage.cpp b/Source/bmalloc/bmalloc/Gigacage.cpp
index d10214881d9b..b47532b5e3ed 100644
--- a/Source/bmalloc/bmalloc/Gigacage.cpp
+++ b/Source/bmalloc/bmalloc/Gigacage.cpp
@@ -135,6 +135,7 @@ void ensureGigacage()
             // largest value of n so that n! <= 2^64.
             static_assert(NumberOfKinds <= 21, "too many kinds");
             uint64_t random;
+            /*
             cryptoRandom(reinterpret_cast<unsigned char*>(&random), sizeof(random));
             for (unsigned i = NumberOfKinds; i--;) {
                 unsigned limit = i + 1;
@@ -142,7 +143,7 @@ void ensureGigacage()
                 random /= limit;
                 std::swap(shuffledKinds[i], shuffledKinds[j]);
             }
-
+            */
             auto alignTo = [] (Kind kind, size_t totalSize) -> size_t {
                 return roundUpToMultipleOf(alignment(kind), totalSize);
             };
diff --git a/Source/bmalloc/bmalloc/VMAllocate.h b/Source/bmalloc/bmalloc/VMAllocate.h
index de8e8b2589f4..1138135fe640 100644
--- a/Source/bmalloc/bmalloc/VMAllocate.h
+++ b/Source/bmalloc/bmalloc/VMAllocate.h
@@ -123,7 +123,9 @@ inline void vmValidatePhysical(void* p, size_t vmSize)
 inline void* tryVMAllocate(size_t vmSize, VMTag usage = VMTag::Malloc)
 {
     vmValidate(vmSize);
-    void* result = mmap(0, vmSize, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANON | BMALLOC_NORESERVE, static_cast<int>(usage), 0);
+    static long long mmapPrefix = 1;
+    void* result = mmap((void*)(mmapPrefix*0x10000000000ll), vmSize, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANON | BMALLOC_NORESERVE, static_cast<int>(usage), 0);
+    mmapPrefix++;
     if (result == MAP_FAILED)
         return nullptr;
     return result;