There was an unlikely but dangerous race condition in monitorRelease
such that when a thread released a monitor and then tried to notify
the next thread in line, the latter thread might exit before it can be
notified. This potentially led to a crash as the former thread tried
to acquire and notify the latter thread's private lock after it had
been disposed.
The solution is to do as we do in the interrupt and join cases: call
acquireSystem first and thereby either block the target thread from
exiting until we're done or find that it has already exited, in which
case nothing needs to be done.
I also looked at monitorNotify to see if we have a similar bug there,
but in that case the target thread can't exit without first acquiring
and releasing the monitor, and since we ensure that no thread can
execute monitorNotify without holding the monitor, there's no
potential for a race.
In makeCodeImage, we were passing zero to Promise::Listener::resolve,
which would lead to an assertion error if the address of the code
image was further from the base of the address space (i.e. zero) than
could be spanned by a jump on the target architecture. Since, in this
context, we immediately overwrite the value stored, we may pass
whatever we want to this function (we're only calling it so we can
retrieve the location of the value in the image), and the code image
pointer is a better choice for the above reason.
When trying to create an array class, we try to resolve
java.lang.Object so we can use its vtable in the array class.
However, if Object is missing, we'll try to create and throw a
ClassNotFoundException, which requires creating an array to store the
stack trace, which requires creating an array class, which requires
resolving Object, etc.. This commit short-circuits this process by
telling resolveClass not to create and throw an exception if it can't
find Object.
While doing the above work, I noticed that the implementations of
Classpath::makeThrowable in classpath-avian.cpp and
classpath-openjdk.cpp were identical, so I made makeThrowable a
top-level function.
Finally, I discovered that Thread.setDaemon can only be called before
the target thread has been started, which allowed me to simplify the
code to track daemon threads in the VM.
We have to be careful about how we calculate return addresses on ARM
due to padding introduced by constant pools interspersed with code.
When calculating the offset of code where we're inserting a constant
pool, we want the offset of the end of the pool for jump targets, but
we want the offset just prior to the beginning of the pool (i.e. the
offset of the instruction responsible for jumping past the pool) when
calculating a return address.
The code added to runJavaThread was unecessary and harmful since it
allowed the global daemon thread count to become permanently
out-of-sync with the actual number of daemon threads.
This mainly involves some makefile ugliness to work around bugs in the
native Windows OpenJDK code involving conflicting static and
not-static declarations which GCC 4.0 and later justifiably reject but
MSVC tolerates.
We weren't properly handling the case where a 64-bit value is
multipled with itself in multiplyRR, leading to wrong code. Also,
addCarryCR didn't know how to handle constants more than 8-bits wide.
