Can't figure out VerifyFrameDoesNotEscape

[Timothy Baldridge]

I've been playing around with a simple BF interpreter written in Truffle.
Last night I got this error for the first time:

[thread:1] scope:
  [thread:1] scope: Truffle
    [thread:1] scope: Truffle.createGraph
      [thread:1] scope: Truffle.createGraph.VerifyFrameDoesNotEscape
        [thread:1] scope:
Truffle.createGraph.VerifyFrameDoesNotEscape.InterceptException
        Exception occurred in scope:
Truffle.createGraph.VerifyFrameDoesNotEscape.InterceptException
        Context obj com.oracle.graal.nodes.util.GraphUtil$2: Frame escapes
at: 67|MethodCallTarget#HotSpotMethod<BFNode.execute(VirtualFrame, byte[],
int)>

My AST is available here :
https://bitbucket.org/cint/trufflebf/src/274c7f80c83936d4bf705197f97c825cd40d0fc0/src/trufflebf/nodes?at=master

As you can see, all my children are marked with @Child and are private
final. What am I doing wrong?

Thanks!

Timothy Baldridge