tree 86154f70ec4a971540363673236bf6b3ff81593c
parent 9d4d13f38398e880e610323242fe73d609bac40d
author Andreas Gampe <agampe@google.com> 1429853027 -0700
committer Andreas Gampe <agampe@google.com> 1429899440 -0700

ART: Check for duplicate classes when loading oat files

Oat files are usually produced standalone, and the compilers take
advantage of any information they get. It is thus possible that
when compile-time and runtime class-path are not the same, classes
are resolved differently and optimized code is incorrect.

This is a very conservative check, scanning the complete class tables
of dex files. In case any duplicate class is found, the new oat file
will be rejected and the original dex files will be used in interpreted
mode.

A possible refinement to this is actual tracking of the compile-time
class-path instead. That is however significantly complicated by the
DexFile API and the non-standard uses it allows.

An alternative for both optimized code and correct resolution is
native multidex. Apps should switch to multidex and benefit from
the optimization as well as the shift of all compile time to install
time. Split APKs are currently compiled separately, but it is a goal
to change that install flow to simulated multidex.

Change-Id: Ib9e0db5091e060e3bb2c0e5e6c007430becbfc21