CFG analysis does not handle properly SDFGs with structurally inaccessible states

[kotsaloscv]

There are some changes from DaCe v0.16 to v0.16.1 especially in the CFG analysis that appear to be incompatible with SDFGs that have structurally inaccessible states. There is a workaround involving calling DeadStateElimination first to remove those states so that they don't cause issues in subsequent passes.

The error I get is the following:

_external_src/gt4py/src/gt4py/next/program_processors/runners/dace_iterator/__init__.py:302: in build_sdfg_from_itir
    sdfg.simplify()
_external_src/dace/dace/sdfg/sdfg.py:2384: in simplify
    return SimplifyPass(validate=validate, validate_all=validate_all, verbose=verbose).apply_pass(self, {})
_external_src/dace/dace/transformation/passes/simplify.py:113: in apply_pass
    result = super().apply_pass(sdfg, pipeline_results)
_external_src/dace/dace/transformation/pass_pipeline.py:547: in apply_pass
    newret = super().apply_pass(sdfg, state)
_external_src/dace/dace/transformation/pass_pipeline.py:502: in apply_pass
    r = self.apply_subpass(sdfg, p, state)
_external_src/dace/dace/transformation/passes/simplify.py:90: in apply_subpass
    ret = p.apply_pass(sdfg, state)
_external_src/dace/dace/transformation/passes/constant_propagation.py:141: in apply_pass
    internal = self.apply_pass(node.sdfg, _, const_syms)
_external_src/dace/dace/transformation/passes/constant_propagation.py:141: in apply_pass
    internal = self.apply_pass(node.sdfg, _, const_syms)
_external_src/dace/dace/transformation/passes/constant_propagation.py:72: in apply_pass
    per_state_constants: Dict[SDFGState, Dict[str, Any]] = self.collect_constants(sdfg, initial_symbols)
_external_src/dace/dace/transformation/passes/constant_propagation.py:196: in collect_constants
    for state in optional_progressbar(cfg.stateorder_topological_sort(sdfg), 'Collecting constants',
_external_src/dace/dace/cli/progress.py:55: in optional_progressbar
    for counter, elem in enumerate(iter):
_external_src/dace/dace/sdfg/analysis/cfg.py:296: in stateorder_topological_sort
    ptree = state_parent_tree(sdfg, loopexits)
_external_src/dace/dace/sdfg/analysis/cfg.py:87: in state_parent_tree
    for be in back_edges(sdfg, idom, alldoms):
_external_src/dace/dace/sdfg/analysis/cfg.py:67: in back_edges
    return [e for e in sdfg.edges() if e.dst in alldoms[e.src]]
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 

.0 = <list_iterator object at 0x32fc44a30>

>   return [e for e in sdfg.edges() if e.dst in alldoms[e.src]]
E   KeyError: SDFGState (join)

_external_src/dace/dace/sdfg/analysis/cfg.py:67: KeyError

Workaround code (thanks to @alexnick83), before applying simplify to the corresponding SDFG:

import dace
from dace.transformation.pass_pipeline import Pipeline
from dace.transformation.passes import DeadStateElimination

sdfg = dace.SDFG.from_file('sdfg_before_simplify.sdfg')
my_pipeline = Pipeline([DeadStateElimination()])
for sd in sdfg.all_sdfgs_recursive():
    my_pipeline.apply_pass(sd, {})

I have attached the SDFG that causes this issue. While for DaCe v0.16 everything works as expected, for DaCe v0.16.1 I get the error above.

sdfg_v0.16_after_simplify.json
sdfg_v0.16_before_simplify.json
sdfg_v0.16.1_before_simplify.json

cc: @alexnick83