8171221: Remove -XX:+CheckMemoryInitialization

Reviewed-by: ayang, shade

Author: Thomas Schatzl

src/hotspot/share/gc/shared/collectedHeap.cpp

@@ -400,17 +400,6 @@ void CollectedHeap::set_gc_cause(GCCause::Cause v) {
   _gc_cause = v;
 }
 
-#ifndef PRODUCT
-void CollectedHeap::check_for_non_bad_heap_word_value(HeapWord* addr, size_t size) {
-  if (CheckMemoryInitialization && ZapUnusedHeapArea) {
-    // please note mismatch between size (in 32/64 bit words), and ju_addr that always point to a 32 bit word
-    for (juint* ju_addr = reinterpret_cast<juint*>(addr); ju_addr < reinterpret_cast<juint*>(addr + size); ++ju_addr) {
-      assert(*ju_addr == badHeapWordVal, "Found non badHeapWordValue in pre-allocation check");
-    }
-  }
-}
-#endif // PRODUCT
-
 size_t CollectedHeap::max_tlab_size() const {
   // TLABs can't be bigger than we can fill with a int[Integer.MAX_VALUE].
   // This restriction could be removed by enabling filling with multiple arrays.

src/hotspot/share/gc/shared/collectedHeap.hpp

@@ -181,8 +181,6 @@ class CollectedHeap : public CHeapObj<mtGC> {
   virtual void trace_heap(GCWhen::Type when, const GCTracer* tracer);
 
   // Verification functions
-  virtual void check_for_non_bad_heap_word_value(HeapWord* addr, size_t size)
-    PRODUCT_RETURN;
   debug_only(static void check_for_valid_allocation_state();)
 
  public:

src/hotspot/share/gc/shared/memAllocator.cpp

@@ -61,7 +61,6 @@ class MemAllocator::Allocation: StackObj {
   void notify_allocation_low_memory_detector();
   void notify_allocation_jfr_sampler();
   void notify_allocation_dtrace_sampler(JavaThread* thread);
-  void check_for_bad_heap_word_value() const;
 #ifdef ASSERT
   void check_for_valid_allocation_state() const;
 #endif
@@ -83,7 +82,6 @@ class MemAllocator::Allocation: StackObj {
 
   ~Allocation() {
     if (!check_out_of_memory()) {
-      verify_after();
       notify_allocation(_thread);
     }
   }
@@ -150,22 +148,6 @@ void MemAllocator::Allocation::verify_before() {
   assert(!Universe::heap()->is_gc_active(), "Allocation during gc not allowed");
 }
 
-void MemAllocator::Allocation::verify_after() {
-  NOT_PRODUCT(check_for_bad_heap_word_value();)
-}
-
-void MemAllocator::Allocation::check_for_bad_heap_word_value() const {
-  MemRegion obj_range = _allocator.obj_memory_range(obj());
-  HeapWord* addr = obj_range.start();
-  size_t size = obj_range.word_size();
-  if (CheckMemoryInitialization && ZapUnusedHeapArea) {
-    for (size_t slot = 0; slot < size; slot += 1) {
-      assert((*(intptr_t*) (addr + slot)) != ((intptr_t) badHeapWordVal),
-             "Found badHeapWordValue in post-allocation check");
-    }
-  }
-}
-
 #ifdef ASSERT
 void MemAllocator::Allocation::check_for_valid_allocation_state() const {
   // How to choose between a pending exception and a potential
@@ -260,7 +242,6 @@ HeapWord* MemAllocator::mem_allocate_outside_tlab(Allocation& allocation) const
     return mem;
   }
 
-  NOT_PRODUCT(Universe::heap()->check_for_non_bad_heap_word_value(mem, _word_size));
   size_t size_in_bytes = _word_size * HeapWordSize;
   _thread->incr_allocated_bytes(size_in_bytes);
 

src/hotspot/share/runtime/globals.hpp

@@ -887,10 +887,6 @@ const int ObjectAlignmentInBytes = 8;
   develop(bool, FLSVerifyDictionary, false,                                 \
           "Do lots of (expensive) FLS dictionary verification")             \
                                                                             \
-                                                                            \
-  notproduct(bool, CheckMemoryInitialization, false,                        \
-          "Check memory initialization")                                    \
-                                                                            \
   product(uintx, ProcessDistributionStride, 4,                              \
           "Stride through processors when distributing processes")          \
           range(0, max_juint)                                               \