src/java.base/share/classes/jdk/internal/foreign/AbstractMemorySegmentImpl.java

*** 262,27 ***
              final long thatStart = that.unsafeGetOffset();
              final long thisEnd = thisStart + this.byteSize();
              final long thatEnd = thatStart + that.byteSize();
  
              if (thisStart < thatEnd && thisEnd > thatStart) {  //overlap occurs
!                 long offsetToThat = this.segmentOffset(that);
                  long newOffset = offsetToThat >= 0 ? offsetToThat : 0;
                  return Optional.of(asSlice(newOffset, Math.min(this.byteSize() - newOffset, that.byteSize() + offsetToThat)));
              }
          }
          return Optional.empty();
      }
  
-     @Override
-     public final long segmentOffset(MemorySegment other) {
-         AbstractMemorySegmentImpl that = (AbstractMemorySegmentImpl) Objects.requireNonNull(other);
-         if (unsafeGetBase() == that.unsafeGetBase()) {
-             return that.unsafeGetOffset() - this.unsafeGetOffset();
-         }
-         throw new UnsupportedOperationException("Cannot compute offset from native to heap (or vice versa).");
-     }
- 
      @Override
      public void load() {
          throw notAMappedSegment();
      }
  
--- 262,18 ---
              final long thatStart = that.unsafeGetOffset();
              final long thisEnd = thisStart + this.byteSize();
              final long thatEnd = thatStart + that.byteSize();
  
              if (thisStart < thatEnd && thisEnd > thatStart) {  //overlap occurs
!                 long offsetToThat = that.address() - this.address();
                  long newOffset = offsetToThat >= 0 ? offsetToThat : 0;
                  return Optional.of(asSlice(newOffset, Math.min(this.byteSize() - newOffset, that.byteSize() + offsetToThat)));
              }
          }
          return Optional.empty();
      }
  
      @Override
      public void load() {
          throw notAMappedSegment();
      }