src/hotspot/cpu/aarch64/compressedKlass_aarch64.cpp

*** 116,18 ***
    }
  
    return result;
  }
  
! void CompressedKlassPointers::initialize(address addr, size_t len) {
    constexpr uintptr_t unscaled_max = nth_bit(32);
    assert(len <= unscaled_max, "Klass range larger than 32 bits?");
  
-   // Shift is always 0 on aarch64.
    _shift = 0;
  
-   // On aarch64, we don't bother with zero-based encoding (base=0 shift>0).
    address const end = addr + len;
    _base = (end <= (address)unscaled_max) ? nullptr : addr;
  
    _range = end - _base;
  }
--- 116,33 ---
    }
  
    return result;
  }
  
! bool CompressedKlassPointers::pd_initialize(address addr, size_t len) {
+ 
+   if (tiny_classpointer_mode()) {
+     // In tiny-classpointer mode, we do what all other platforms do.
+     return false;
+   }
+ 
+   // Aarch64 uses an own initialization logic that avoids zero-base shifted mode
+   // (_base=0 _shift>0), instead preferring non-zero-based mode with shift=0
    constexpr uintptr_t unscaled_max = nth_bit(32);
    assert(len <= unscaled_max, "Klass range larger than 32 bits?");
  
    _shift = 0;
  
    address const end = addr + len;
    _base = (end <= (address)unscaled_max) ? nullptr : addr;
  
    _range = end - _base;
+ 
+ #ifdef ASSERT
+   _klass_range_start = addr;
+   _klass_range_end = addr + len;
+   calc_lowest_highest_narrow_klass_id();
+   sanity_check_after_initialization();
+ #endif
+ 
+   return true;
  }