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Improved opt_muxtree

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This commit is contained in:
Clifford Wolf 2015-01-17 12:05:19 +01:00
parent b32ba6f568
commit 3628ca989c
1 changed files with 38 additions and 4 deletions
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42
passes/opt/opt_muxtree.cc
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@ -256,7 +256,7 @@ struct OptMuxtreeWorker
list.push_back(value);
}
std::vector<int> sig2bits(RTLIL::SigSpec sig)
std::vector<int> sig2bits(RTLIL::SigSpec sig, bool skip_non_wires = true)
{
std::vector<int> results;
assign_map.apply(sig);
@ -271,7 +271,8 @@ struct OptMuxtreeWorker
bit2num[info.bit] = info.num;
}
results.push_back(bit2num[bit]);
}
} else if (!skip_non_wires)
results.push_back(-1);
return results;
}
@ -285,7 +286,7 @@ struct OptMuxtreeWorker
// database of known active signals
// the 2nd dimension is the list of or-ed signals. so we know that
// for each i there is a j so that known_active[i][j] points to an
// inactive control signal.
// active control signal.
std::vector<std::vector<int>> known_active;
// this is just used to keep track of visited muxes in order to prohibit
@ -331,10 +332,43 @@ struct OptMuxtreeWorker
}
}
void replace_known(knowledge_t &knowledge, muxinfo_t &muxinfo, IdString portname)
{
SigSpec sig = muxinfo.cell->getPort(portname);
bool did_something = false;
std::vector<int> bits = sig2bits(sig, false);
for (int i = 0; i < GetSize(bits); i++) {
if (bits[i] < 0)
continue;
if (knowledge.known_inactive[bits[i]]) {
sig[i] = State::S0;
did_something = true;
} else {
for (auto &it : knowledge.known_active)
if (GetSize(it) == 1 && it.front() == bits[i]) {
sig[i] = State::S1;
did_something = true;
break;
}
}
}
if (did_something) {
log(" Replacing known input bits on port %s of cell %s: %s -> %s\n", log_id(portname),
log_id(muxinfo.cell), log_signal(muxinfo.cell->getPort(portname)), log_signal(sig));
muxinfo.cell->setPort(portname, sig);
}
}
void eval_mux(knowledge_t &knowledge, int mux_idx)
{
muxinfo_t &muxinfo = mux2info[mux_idx];
// set input ports to constants if we find known active or inactive signals
replace_known(knowledge, muxinfo, "\\A");
replace_known(knowledge, muxinfo, "\\B");
// if there is a constant activated port we just use it
for (size_t port_idx = 0; port_idx < muxinfo.ports.size()-1; port_idx++)
{
@ -360,7 +394,7 @@ struct OptMuxtreeWorker
}
// compare ports with known_inactive and known_active signals. If all control
// signals of the port are know_inactive or if the control signals of all other
// signals of the port are known_inactive or if the control signals of all other
// ports are known_active this port can't be activated. this loop includes the
// default port but no known_inactive match is performed on the default port.
for (size_t port_idx = 0; port_idx < muxinfo.ports.size(); port_idx++)