Two asserts where only 1 is needed?

Peter B. Kessler Peter.Kessler at Sun.COM
Mon Jul 16 21:22:41 UTC 2007

In hotspot/src/share/vm/utilities/taskqueue.hpptaskqueue.hpp,

     template<class E>
     GenericTaskQueue<E>::GenericTaskQueue():TaskQueueSuper() {
       assert(sizeof(Age) == sizeof(jint), "Depends on this.");

which seems good and proper (except it doesn't say why it
depends on the sizes being equal).  But there's also

     template<class E>
     bool GenericTaskQueue<E>::
     pop_local_slow(juint localBot, Age oldAge) {
       assert(sizeof(Age) == sizeof(jint) && sizeof(jint) == sizeof(juint),
              "Assumption about CAS unit.");

which checks an additional condition and has a better failure

Since Atomic::cmpxchg only deals in jint's, I don't see the reason
for the check of sizeof(juint).  This is the only place in the VM
that checks sizeof(jint) == sizeof(juint).

Can anyone think of a reason for the assert at each call of
pop_local_slow if we've passed already passed the assert in
the ctor?

			... peter

P.S. I'll probably fix the weird-line wrapping in the declaration
of GenericTaskQueue<E>::pop_local_slow while I'm in there.

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