RFR (S) 8013942: JSR 292: assert(type() == T_OBJECT) failed: type check

[serguei.spitsyn at oracle.com]

Thanks, Coleen!
Serguei

On 6/26/14 12:38 PM, Coleen Phillimore wrote:
>
> Serguei,
> This looks good.
> Coleen
>
> On 6/25/14, 9:57 AM, serguei.spitsyn at oracle.com wrote:
>> Please, review the fix for:
>>   https://bugs.openjdk.java.net/browse/JDK-8013942
>>
>>
>> Open webrev:
>> http://cr.openjdk.java.net/~sspitsyn/webrevs/2014/hotspot/8013942-JVMTI-lobj.1 
>>
>>
>>
>> Summary:
>>
>>   This is a Nightly Stabilization issue.
>>
>>   The problem is that the JVMTI GetLocalObject() function is hitting 
>> the assert
>>   as the type of the local at current bci is not T_OBJECT as expected.
>>   It is because this local is alive only in a narrow scope of one 
>> condition in the method but current bci is out of this csope.
>>
>>   A fragment from the target method:
>>
>>     static Class<?> canonicalize(Class<?> t, int how) {
>>         Class<?> ct; <== The local
>>         if (t == Object.class) {
>>             // no change, ever
>>         } else if (!t.isPrimitive()) {
>>             switch (how) {
>>                 case UNWRAP:
>>                     ct = Wrapper.asPrimitiveType(t); <== Initialized 
>> here
>>                     if (ct != t) return ct;
>>                     break;
>>                 case RAW_RETURN:
>>                 case ERASE:
>>                     return Object.class;
>>             }
>>         } else if (t == void.class) {                <== The 
>> GetLocalObject() is called with bci in this block
>>             // no change, usually
>>             switch (how) {
>>                 case RAW_RETURN:
>>                     return int.class;
>>                 case WRAP:
>>                     return Void.class;
>>             }
>>         } else {
>>         . . .
>>
>>   The local 'ct' is only alive in the block of condition "if 
>> (!t.isPrimitive())".
>>   However, it is dead local in the next block.
>>
>>   The fix suggested in the webrev above is to use the oop_mask for 
>> the method's current bci.
>>   It tells when the local is dead in the scope of this bci.
>>   Return the JVMTI_ERROR_INVALID_SLOT error in such a case.
>>
>>   The fix also includes the tweeks which are necessary to enable the 
>> InterpreterOopMap.is_dead()
>>   function in the product mode as it was originally defined only 
>> under "#ifdef ENABLE_ZAP_DEAD_LOCALS".
>>   This makes the code in the oopMapCache.?pp a little bit more simple.
>>
>>
>> Testing:
>>   Running the failing tests: vm.mlvm.indy.func.jvmti
>>   In progress: nsk.jvmti, nsk.jdi, nsk.jdwp test runs on sparcv9 and 
>> amd64
>>
>>
>> Thanks,
>> Serguei
>>
>