(M) RFR: 8200167: Validate more special case invocations

Karen Kinnear karen.kinnear at oracle.com
Thu Apr 26 21:21:50 UTC 2018

Looks good!

Thank you so much David and Vladimir for all the work to cover the corner cases.


> On Apr 26, 2018, at 12:12 AM, David Holmes <david.holmes at oracle.com> wrote:
> Revised webrev: http://cr.openjdk.java.net/~dholmes/8200167/webrev.v2/
> Karen formulated an additional test scenario invoking Object methods through an interface reference, which when turned into a new testcase demonstrated that the receiver typecheck was also missing in that case for Methodhandle's from findSpecial.
> Again Vladimir Ivanov formulated the fix for this. Thanks Vladimir!
> Summary of changes from original webrev:
> - We introduce a new version of DirectMethodHandle.preparedlambdaForm that takes the caller class as a parameter, and that class is checked for being an interface (not the method's declaring class) to trigger the switch to LF_SPECIAL_IFC. (This obviously addresses one problem with invoking Object methods - as Object is not an interface - but by itself did not fix the problem.)
> - We introduce a new LambdaForm kind, DIRECT_INVOKE_SPECIAL_IFC, which we use when dealing with LF_INVSPECIAL_IFC. (This was the key in ensuring the receiver typecheck via Special.checkReceiver remained in the generated code.)
> - In the test we:
>  - introduce a new invokeDirect testcase for Object.toString(), but we need to do that via a modified jcod file (as javac generates an invokevirtual)
>  - introduce the new invokeSpecialObjectMH(I2 i) call for the MH case.
> Thanks,
> David
> On 17/04/2018 6:48 PM, David Holmes wrote:
>> Bug: https://bugs.openjdk.java.net/browse/JDK-8200167
>> webrev: http://cr.openjdk.java.net/~dholmes/8200167/webrev/
>> Credit to John Rose and Vladimir Ivanov for the form of the MH fix; and to Tobias Hartmann for the C1 fix. Their help was very much appreciated (and needed!).
>> tl;dr version: there are some places where badly formed interface method calls (which are not detected by the verifier) were missing runtime checks on the type of the receiver. Similar issues have been fixed in the past and this was a remaining hole in relation to invokespecial semantics and interface calls via MethodHandles. It also turned out there was an issue in C1 that affected direct invokespecial calls.
>> Description of changes:
>> - src/java.base/share/classes/java/lang/invoke/MethodTypeForm.java
>> Added a new form LF_INVSPECIAL_IFC for invokespecial of interface methods.
>> - src/java.base/share/classes/java/lang/invoke/MethodHandles.java
>> Renamed callerClass parameter to boundCallerClass, where it originates from findBoundCallerClass. The name "callerClass" is misleading because most of the time it is NULL!
>> In getDirectMethodCommon, pass the actual caller class (lookupClass) to DirectMethodHandle.make. And correct the comment about restrictReceiver.
>> - src/java.base/share/classes/java/lang/invoke/DirectMethodHandle.java
>> DirectMethodHandle.make now takes a callerClass parameter (which may be null).
>> DirectMethodHandle make "receiver" parameter is renamed "refc" as it is not the receiver (it's the resolved type of the method holder ie REFC).
>> The Special subclass now takes a "checkClass" parameter which is either refc, or callerClass. This is what we will check the receiver against.
>> In preparedLambdaForm we switch from LF_INVSPECIAL to LF_INVSPECIAL_IFC if the target method is in an interface.
>> In makePreparedLambdaForm we augment the needsReceiverCheck test to include LF_INVSPECIAL_IFC. (So we will not be doing a new receiver type check on all invokespecials, just those involving interface methods.)
>> Added DMH.checkReceiver which is overridden by both the Special and Interface subclasses.
>> - src/hotspot/share/c1/c1_Canonicalizer.cpp
>> Don't optimize away the checkcast when it is an invokespecial receiver check.
>> - test/jdk/java/lang/invoke/SpecialInterfaceCall.java
>> (I've moved this test back and forth between hotspot/runtime and j.l.invoke as it spans direct calls and MH calls. But I think on balance it lands better here.)
>> The test sets up direct interface method calls for which invokespecial is generated by javac, and similarly it creates MethodHandles with invokespecial semantics. The should-not-throw cases are trivial. The should-throw cases involve MH wizardry.
>> The test is broken into three parts to check the behaviour on first use (when the method has to be initially resolved); on second use (to test we don't use the cpcache in a way that is invalid); and again after forcing JIT compilation of the calls.
>> The test is run 5 times to exercise the interpreter (yes the multiple runs internal to the test are redundant in this case, but it's much simpler to just run it all than try to work out what needs to be run); the three variants of using C1, plus a C2 only run.
>> ---
>> Testing:
>>   - the new test of course
>>   - hotspot/runtime/*
>>   - hotspot/compiler/jsr292
>>   - jdk/java/lang/invoke
>>   - hs tiers 1 and 2
>>   - jdk tiers 1, 2 and 3
>> Plus some related closed tests.
>> Thanks,
>> David
>> -----

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