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

[Vladimir Ivanov]

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-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
>