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

[Coleen Phillimore]

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
>