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write_xaiger: Detect and error on combinatorial loops

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This commit is contained in:
Anhijkt 2025-02-14 01:21:39 +02:00
parent df3c62a4ed
commit a8052f653a
1 changed files with 22 additions and 0 deletions
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22
backends/aiger/xaiger.cc
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@ -53,6 +53,8 @@ struct XAigerWriter
dict<SigBit, float> arrival_times;
vector<pair<int, int>> aig_gates;
vector<SigBit> bit2aig_stack;
int next_loop_check = 1024;
vector<int> aig_outputs;
int aig_m = 0, aig_i = 0, aig_l = 0, aig_o = 0, aig_a = 0;
@ -76,6 +78,24 @@ struct XAigerWriter
return it->second;
}
if (GetSize(bit2aig_stack)== next_loop_check) {
for (int i = 0; i < next_loop_check; ++i)
{
SigBit report_bit = bit2aig_stack[i];
if (report_bit != bit)
continue;
for (int j = i; j < next_loop_check; ++j) {
report_bit = bit2aig_stack[j];
if (report_bit.is_wire() && report_bit.wire->name.isPublic())
break;
}
log_error("Found combinatorial logic loop while processing signal %s.\n", log_signal(report_bit));
}
next_loop_check *= 2;
}
bit2aig_stack.push_back(bit);
// NB: Cannot use iterator returned from aig_map.insert()
// since this function is called recursively
@ -93,6 +113,8 @@ struct XAigerWriter
a = bit2aig(alias_map.at(bit));
}
bit2aig_stack.pop_back();
if (bit == State::Sx || bit == State::Sz) {
log_debug("Design contains 'x' or 'z' bits. Treating as 1'b0.\n");
a = aig_map.at(State::S0);