Commit b62e1bb1 by Alexandre Duret-Lutz

### simplify_acc: fix an infinite loop

```* spot/twaalgos/cleanacc.cc (fuse_mark_here): Fix incorrect cancelling
of n-ary subterms, causing an invalid acceptance condition, and then
an infinite loop.
* tests/python/simplacc.py: Add test case.```
parent 68012e6a
 ... ... @@ -367,7 +367,7 @@ namespace spot return {}; } acc_cond::mark_t find_interm_rec(acc_cond::acc_word* pos) acc_cond::mark_t find_interm_rec(const acc_cond::acc_word* pos) { acc_cond::acc_op wanted; auto topop = pos->sub.op; ... ... @@ -489,13 +489,13 @@ namespace spot assert(topop == acc_cond::acc_op::Or); } // Return a vector of "singleton-sets" of // Build a vector of "singleton-sets" of // the wanted type in the operand of the // pointed Or/And operator. For instance, // assuming wanted=Inf and pos points to // // Inf({1})|Inf({2,3})|Fin({4}) // |Inf({5})|Inf({5})|Inf({6}) // |Inf({5})|Inf({5,6}) // // This returns [({1}, Inf({1})), // ({5}, Inf({5}))]]. ... ... @@ -522,9 +522,8 @@ namespace spot break; case acc_cond::acc_op::And: case acc_cond::acc_op::Or: // On // Fin(a)&(Fin(b)&Inf(c)|Fin(d)) // where we'd like to return [({a},...), // On Fin(a)&(Fin(b)&Inf(c)|Fin(d)) // we'd like to build [({a},...), // ({b,d},...)] and decide later that // {b,d} can receive {a} if they // (b and d) are both used once. ... ... @@ -556,12 +555,18 @@ namespace spot if (p.first != can_receive && p.first.lowest() == p.first) { to_fuse.emplace_back(p.first, can_receive); // Mark fused singletons as false, // so that a future call to // find_fusable() ignores them. if (p.second->sub.op == acc_cond::acc_op::Fin) p.second->sub.op = acc_cond::acc_op::Inf; else else if (p.second->sub.op == acc_cond::acc_op::Inf) p.second->sub.op = acc_cond::acc_op::Fin; else continue; p.second[-1].mark = {}; to_fuse.emplace_back(p.first, can_receive); } }; ... ...
 ... ... @@ -38,7 +38,19 @@ explicit-labels trans-acc complete properties: deterministic --BODY-- State: 0 [!0&!1] 0 {2} [0&1] 1 {0 5} [0&!1] 1 {0 2 5} [!0&1] 2 {1} State: 1 [0&1] 1 {0} [!0&!1] 1 {2} [0&!1] 1 {0 2} [!0&1] 2 {1} State: 2 [!0&!1] 0 {2 3} [0&!1] 0 {0 2 3 5} [!0&1] 2 {1 4} [0&1] 3 {0 5} State: 3 [!0&!1] 0 {2 3} [0&!1] 0 {0 2 3 5} [!0&1] 2 {1 4} [0&1] 3 {0} --END--""")) [!0&1] 2 {1 4} [0&1] 3 {0} --END-- /* This one caused an infinite loop in the simplification code. */ HOA: v1 States: 10 Start: 0 AP: 2 "p0" "p1" Acceptance: 6 (((Fin(4) & (Fin(3) | (Fin(3) & Inf(1))) & (Inf(0)&Inf(5))) | (Fin(5) & Fin(2))) & Inf(5)) | Inf(5) | Inf(0) properties: trans-labels explicit-labels trans-acc --BODY-- State: 0 [!0&!1] 2 [!0&!1] 7 {1} [!0&!1] 6 State: 1 [!0&!1] 5 {1 5} [0&!1] 9 {3} [!0&1] 1 {0} [!0&!1] 4 {0 3} State: 2 [0&1] 1 {1} State: 3 [!0&1] 8 {4} State: 4 [!0&!1] 0 {5} [!0&1] 3 {4} State: 5 [!0&1] 4 {3 5} [!0&1] 3 {2 4} [!0&1] 2 {2 3} [!0&!1] 0 {0} [!0&1] 7 {0 4 5} [0&1] 5 {2} State: 6 [0&!1] 7 [0&!1] 1 {1 4} [0&1] 4 {1 4} State: 7 [0&1] 3 {2 3} [0&1] 0 [!0&!1] 6 [0&1] 1 State: 8 [0&1] 3 [!0&!1] 0 [0&1] 9 State: 9 [0&!1] 7 {4 5} [!0&1] 8 {0} [0&1] 9 --END-- """)) res = [] for a in auts: ... ... @@ -62,4 +74,6 @@ assert res == [ 'Fin(0) | (Fin(2) & Inf(1))', '((Fin(1) | Inf(2)) & Inf(5)) | (Fin(0) & (Fin(1) | (Fin(3) & Inf(4))))', '(Fin(5) | (Fin(2) & Inf(1))) & (Inf(0) | ((Fin(4) | Inf(3)) & Inf(1)))', 'Inf(1) | Inf(0)', 'Fin(1) & Fin(0)', ]
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