CutBackEdge.bpl(12,5): Error BP5005: This loop invariant might not be maintained by the loop.
Execution trace:
    CutBackEdge.bpl(7,3): entry
    CutBackEdge.bpl(11,3): block850
CutBackEdge.bpl(22,5): Error BP5004: This loop invariant might not hold on entry.
Execution trace:
CutBackEdge.bpl(28,5): Error BP5001: This assertion might not hold.
Execution trace:
    CutBackEdge.bpl(27,3): L
CutBackEdge.bpl(40,5): Error BP5004: This loop invariant might not hold on entry.
Execution trace:

Boogie program verifier finished with 1 verified, 4 errors