tree f39728cdafc7810004d51c0bef2728b98993daa9
parent 64a102dde8c5daad83b991710decb418ce43aac5
author Vladimir Marko <vmarko@google.com> 1497278516 +0100
committer Vladimir Marko <vmarko@google.com> 1500554106 +0100

ART: Change method lookup to be more consistent to JLS and the RI.

The method lookup for different invoke types was previously
widely different and didn't work well with the dex cache
method array where we have only a single slot for each
MethodId. The new behavior is to perform the same lookup for
all cases, distinguishing only between interface and
non-interface referencing class, and to further align the
behavior with the JLS and the RI. Where the JLS conflicts
with the RI, we follow the JLS semantics.

The new lookup for class methods first searches the methods
declared in the superclass chain (ignoring "copied" methods)
and only then looks in the "copied" methods. If the search
in the superclass chain finds a method that has not been
inherited (i.e. either a private method or a package-access
method where one of the classes in the chain does not belong
to the same package, see JLS 8.4.8), we still search the
"copied" methods as there may actually be a method inherited
from an interface. This follows the JLS semantics where
inherited methods are included in the search (JLS 15.12.2.1)
but conflicts with the RI where the private or
package-access method takes precedence over methods
inherited from interfaces.

Note that this search can find an accessible method that is
not inherited by the qualifying type, either for a package
access method when the referrer is in the same package but
the qualifying type is in another package, or for a private
method where the referrer is in the same class but the
qualifying type is actually a subclass. For the moment we
allow such calls and we shall consider whether to throw
an IncompatibleClassChangeError in this situation in future
to comply with JLS 15.12.4.3.

The new lookup for interface methods searches the interface
class, then all the superinterfaces and then the
java.lang.Object class, see implicitly declared methods in
interfaces, JLS 9.2. The search for the maximally-specific
non-abstract superinterface method is not yet implemented,
but the difference should be difficult to observe as the
usual subsequent call to FindVirtualMethodForInterface()
should yield the same result for any matching method.

The new test 162-method-idx-clash exposes several cases
where we previously completely messed up due to the effects
of the DexCache, or where we were out of line with the RI.
It also tests a case where the JLS and the RI disagree and
we follow the JLS.

Test: art/test/run-test --host --jvm 162-method-resolution
Test: m test-art-host-gtest
Test: testrunner.py --host
Test: testrunner.py --host --interp-ac
Test: Nexus 6P boots.
Test: testrunner.py --target
Bug: 62855082
Bug: 30627598
Change-Id: If450c8cff2751369011d649c25d28a482a2c61a3