Reduce dex2oat memory usage from VariableHandleScope.

Pack more handles in FixedSizeHandleScope<>s to reduce the
per-Handle<> overhead.

Measured compilation of a big app using heaptrack:
  before:
    3571397 calls to allocation functions with 2.59MB peak
    consumption from art::MutableHandle<>
    art::ReferenceTypePropagation::HandleCache::NewHandle<>(art::ObjPtr<>)
  after:
    1139808 calls to allocation functions with 1.54MB peak
    consumption from art::MutableHandle<>
    art::ReferenceTypePropagation::HandleCache::NewHandle<>(art::ObjPtr<>)

Test: Rely on TreeHugger.
Bug: 34053922
Change-Id: I160990f3a89aadffc9e6753da30b448937f8eaf0
1 file changed