value set analysis runtime error with bap2

[zhouxuan009]

Value set analysis with bap2 still raise an error at runtime and the error message is as below

The pass "value-set" failed with:
source tid does not represent block

I found that the error is triggered because the cfg of subroutine passed to the fixpoint function has @start-pseudo-node and @exit-pseudo-node

cbat_tools/vsa/value_set/lib/src/cbat_vsa.ml

Line 449 in ce7b339

let cfg = Sub.to_graph s in

Just as the bap document says, as toval to_graph : t -> Graphs.Tid.t, since 2.1 the returned graph contains two pseudo-nodes(http://binaryanalysisplatform.github.io/bap/api/odoc/bap/Bap/Std/Sub/index.html)

Then the code below fails to recognize the pseudo node as basic blocks.

cbat_tools/vsa/value_set/lib/src/cbat_vsa.ml

Line 391 in ce7b339

match (Program.lookup blk_t ctx source) with

I am trying to fix this error. But I can't find any api which can remove the pseudo nodes in cfg