Reduce Partial LSE memory usage.

Instantiate ExecutionSubgraph only for partial singleton
candidates (currently NewInstance, possibly NewArray in the
future). This reduces "LSA" allocations.

Reserve memory for PartialLoadStoreEliminationHelper members
based on the number of partial singletons instead of the
number of reference infos. This reduces "LSE" allocations.

The peak scoped arena allocation for one compiled method
is reduced from
  MEM: used: 97424004, allocated: 99006568, lost: 1115968
    LSA            46015104
    LSE            51408900
down to
  MEM: used: 17000744, allocated: 26713880, lost: 3332496
    GVN            17000744
where the LSA+LSE memory use is lower than GVN use.

(cherry picked from commit 5c824937bb82adbde857bc99cb03c769c9f68f7b)

Test: m test-art-host-gtest
Test: testrunner.py --host --optimizing
Bug: 33650849
Merged-In: I323b9f144b258f0fab034794770971547ce94b59
Change-Id: If3fc9787fc0dc4a1a33dd5ca0f2dc972998c4da7
7 files changed