8256670: Zero: enable compressed oops support back

Reviewed-by: coleenp

Author: shipilev

src/hotspot/share/runtime/arguments.cpp

@@ -1678,7 +1678,6 @@ size_t Arguments::max_heap_for_compressed_oops() {
 }
 
 void Arguments::set_use_compressed_oops() {
-#ifndef ZERO
 #ifdef _LP64
   // MaxHeapSize is not set up properly at this point, but
   // the only value that can override MaxHeapSize if we are
@@ -1699,14 +1698,12 @@ void Arguments::set_use_compressed_oops() {
     }
   }
 #endif // _LP64
-#endif // ZERO
 }
 
 
 // NOTE: set_use_compressed_klass_ptrs() must be called after calling
 // set_use_compressed_oops().
 void Arguments::set_use_compressed_klass_ptrs() {
-#ifndef ZERO
 #ifdef _LP64
   // On some architectures, the use of UseCompressedClassPointers implies the use of
   // UseCompressedOops. The reason is that the rheap_base register of said platforms
@@ -1734,7 +1731,6 @@ void Arguments::set_use_compressed_klass_ptrs() {
     }
   }
 #endif // _LP64
-#endif // !ZERO
 }
 
 void Arguments::set_conservative_max_heap_alignment() {
@@ -1753,7 +1749,6 @@ jint Arguments::set_ergonomics_flags() {
 
   set_conservative_max_heap_alignment();
 
-#ifndef ZERO
 #ifdef _LP64
   set_use_compressed_oops();
 
@@ -1764,7 +1759,6 @@ jint Arguments::set_ergonomics_flags() {
   // Also checks that certain machines are slower with compressed oops
   // in vm_version initialization code.
 #endif // _LP64
-#endif // !ZERO
 
   return JNI_OK;
 }
@@ -4194,8 +4188,6 @@ jint Arguments::apply_ergo() {
   // Clear flags not supported on zero.
   FLAG_SET_DEFAULT(ProfileInterpreter, false);
   FLAG_SET_DEFAULT(UseBiasedLocking, false);
-  LP64_ONLY(FLAG_SET_DEFAULT(UseCompressedOops, false));
-  LP64_ONLY(FLAG_SET_DEFAULT(UseCompressedClassPointers, false));
 #endif // ZERO
 
   if (PrintAssembly && FLAG_IS_DEFAULT(DebugNonSafepoints)) {