Crash from upcall usage

[Mark Hammons]

Hi Panama team,

I was testing my library earlier today, and I noticed that when I call
qsort with integer arrays of size 10000 or greater, I have an increasing
chance (not 100% at 10000) of a jvm crash. I downloaded and used OpenJDK
64-Bit Server VM (build 17-panama+3-167, mixed mode, sharing)
and reran my tests and I think that the crash is being triggered by C2
compilation of a lambda I'm passing to qsort, but I'm not certain.

I've attached the error report and compilation logs of my program.


https://gitlab.com/mhammons/slinc/-/blob/44-crash-on-qsort-benchmarks-when-using-values-larger-than-10000/cstd/test/src/io/gitlab/mhammons/cstd/StdLibSuite.scala#L86
is
the test that crashes. You can run it by running ./mill cstd.test in a
cloned directory.

My library is passing scala lambdas in by generating a lambda (Any, Any) =>
Any that takes the input parameters from foreign and converts them into the
expected types, and converts the output of the original lambda into a
foreign compatible type. This generated lambda is then bound to a method
handle by Using a findVirtual lookup of the appropriate function class,
describing the lambda to the MethodHandle system, and calling asType with
the method handle type that foreign is expecting.

val lambdaMh: MethodHandle = MethodHandles.lookup
.findVirtual(
$classRepr,
"apply",
MT.genericMethodType(${ Expr(inputTypes.size) })
)
.bindTo($wrappedLambda)
.asType(methodType)

Linker.linker.upcallStub(
lambdaMh,
functionDescriptor,
currentScope
)
This code is using macros to create the appropriate lambda types and such,
so it can be a bit hard to read. In any case, the method handle created
this way is then passed into upcallStub. I'm not sure if this is actually a
bug in my library, and I'd like your help in debugging this crash.

Thanks so much,
Mark