8340119: Remove oopDesc::size_might_change()

Reviewed-by: stefank, iwalulya

Author: Thomas Schatzl

src/hotspot/share/oops/oop.cpp

@@ -218,14 +218,3 @@ void oopDesc::release_float_field_put(int offset, jfloat value)       { Atomic::
 
 jdouble oopDesc::double_field_acquire(int offset) const               { return Atomic::load_acquire(field_addr<jdouble>(offset)); }
 void oopDesc::release_double_field_put(int offset, jdouble value)     { Atomic::release_store(field_addr<jdouble>(offset), value); }
-
-#ifdef ASSERT
-bool oopDesc::size_might_change() {
-  // UseParallelGC and UseG1GC can change the length field
-  // of an "old copy" of an object array in the young gen so it indicates
-  // the grey portion of an already copied array. This will cause the first
-  // disjunct below to fail if the two comparands are computed across such
-  // a concurrent change.
-  return Universe::heap()->is_stw_gc_active() && is_objArray() && is_forwarded() && (UseParallelGC || UseG1GC);
-}
-#endif

src/hotspot/share/oops/oop.hpp

@@ -319,8 +319,6 @@ class oopDesc {
 
   // for error reporting
   static void* load_oop_raw(oop obj, int offset);
-
-  DEBUG_ONLY(bool size_might_change();)
 };
 
 // An oopDesc is not initialized via a constructor.  Space is allocated in

src/hotspot/share/oops/oop.inline.hpp

@@ -190,7 +190,7 @@ size_t oopDesc::size_given_klass(Klass* klass)  {
       // skipping the intermediate round to HeapWordSize.
       s = align_up(size_in_bytes, MinObjAlignmentInBytes) / HeapWordSize;
 
-      assert(s == klass->oop_size(this) || size_might_change(), "wrong array object size");
+      assert(s == klass->oop_size(this), "wrong array object size");
     } else {
       // Must be zero, so bite the bullet and take the virtual call.
       s = klass->oop_size(this);