During evacuation, after copying an object to survivor space, it is scanned for further references that may need to be fixed up. This scanning involves calling oop_iterate() on the object.

We noticed that in many benchmarks (dacapo, specjbb) a large part of the copied objects do not contain any references.

I.e. across all dacapo benchmarks, over all gcs, on average only 63% of objects contain references, on Specjbb2005 only 60% (looking at instanceOops, typeArrayOops and objArrayOops which make up >97% of the objects copied).

Investigate if it is possible to have a very fast check whether the copied object potentially contains references or not, skipping the oop iteration call otherwise (and hopefully improving performance in the process).