tree 1141a3f0f91c527dfe28796e88f166d2bc0ed7fd
parent 303b01ed0d36017371e29b1f1e209dd19896ac9e
author buzbee <buzbee@google.com> 1316034013 -0700
committer buzbee <buzbee@google.com> 1316040034 -0700

Fix null check elimination

The existing null check elimination mechanism suffered from the same
limitation as the SSA renaming: it took shortcuts that were valid in
a trace compilation world, but not in a method compilation world.

This CL replaces the old mechanism, and additionally takes advantage
of some the fact that "this" is always non-null, as are objects returned
from OP_NEW_* (thanks Ian!).

Two test cases added.  The one for ensuring that unnecessary null checks
are elminated requires manual inspection.  The other - that we don't
eliminate a necessary null check - is disabled until exceptions are working.

Change-Id: I2a9b72741f56617bf609e4d7c20244796c988f28