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

[Markus Grönlund]

Hi Serguei,


I am not convinced this is the right way to do this - by removing the #ifdef ENABLE_ZAP_DEAD_LOCALS" (which is an COMPILER2 specific #define under an ASSERT), we have now unconditionally increased the bitsize for every oopmap entry to two (compared to one previously) - the inlined oop_map bits_size cache is predefined to hold two words.

This means the oopmap bitmap cache is effectively halved unconditionally.

/Markus


-----Original Message-----
From: Serguei Spitsyn 
Sent: den 27 juni 2014 00:15
To: Vladimir Ivanov; hotspot-dev at openjdk.java.net Developers; serviceability-dev at openjdk.java.net
Subject: Re: RFR (S) 8013942: JSR 292: assert(type() == T_OBJECT) failed: type check

Thanks, Vladimir!
Serguei

On 6/26/14 3:02 PM, Vladimir Ivanov wrote:
> Looks good.
>
> Best regards,
> Vladimir Ivanov
>
> On 6/25/14 5:57 PM, 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-JVM
>> TI-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
>>