Again Trouble with Non-local Returns

[Stefan Marr]

Dear all:

I think, I might have identified one of the potential issues holding back TruffleSOM.

A lucky guess let me to look into the performance of non-local returns once more.

The key part of the micro benchmark looks like this:

    first:  a = ( ^ self second: a )
    second: a = ( ^ self third: a  )
    third:  a = ( a value )
    
    nlr = (
        self first: [^ 1]
    )

Meaning, the #nlr method catches the non-local return of the value 1 and returns to the caller.

The main problem I am seeing is that one of the involved call targets is triggering uncommon traps again.
Think, we had a similar issue a while back, but I didn’t notice any regressions around non-local returns, so, I presume its a slightly different case this time.

The uncommon trap looks like this:

Uncommon trap occurred in com.oracle.graal.truffle.OptimizedCallTarget::callRoot (Graal: installed code has no name)  (@0x0000000110318b2c) thread=6403 reason=null_assert|unreached0 action=none unloaded_class_index=-1 debug_id=0
Uncommon trap   bci=0 pc=271682348, relative_pc=268, method=com.oracle.graal.truffle.OptimizedCallTarget.callRoot([Ljava/lang/Object;)Ljava/lang/Object;, debug_id=0
No speculation


To reproduce you can execute the following:

git clone --recursive https://github.com/SOM-st/TruffleSOM.git
cd TruffleSOM
ant
mx --vm server vm -XX:+UnlockDiagnosticVMOptions -XX:+TraceDeoptimization -Xbootclasspath/a:build/classes:libs/truffle.jar som.vm.Universe -cp Smalltalk Examples/Benchmarks/BenchmarkHarness.som NonLocalReturn 20 0 1000


Any thoughts on the issue, could it be something in Graal?

Thanks
Stefan

-- 
Stefan Marr
INRIA Lille - Nord Europe
http://stefan-marr.de/research/