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Improvements in opt_muxtree

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This commit is contained in:
Clifford Wolf 2015-01-18 12:57:36 +01:00
parent d3b35017f8
commit f630868bc9
2 changed files with 58 additions and 35 deletions
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85
passes/opt/opt_muxtree.cc
View file

@ -62,6 +62,7 @@ struct OptMuxtreeWorker
vector<muxinfo_t> mux2info;
vector<bool> root_muxes;
vector<bool> root_enable_muxes;
OptMuxtreeWorker(RTLIL::Design *design, RTLIL::Module *module) :
design(design), module(module), assign_map(module), removed_count(0)
@ -158,6 +159,7 @@ struct OptMuxtreeWorker
dict<int, pool<int>> mux_to_users;
root_muxes.resize(GetSize(mux2info));
root_enable_muxes.resize(GetSize(mux2info));
for (auto &bi : bit2info) {
for (int i : bi.mux_drivers)
@ -165,8 +167,10 @@ struct OptMuxtreeWorker
mux_to_users[i].insert(j);
if (!bi.seen_non_mux)
continue;
for (int mux_idx : bi.mux_drivers)
for (int mux_idx : bi.mux_drivers) {
root_muxes.at(mux_idx) = true;
root_enable_muxes.at(mux_idx) = true;
}
}
for (auto &it : mux_to_users)
@ -277,14 +281,12 @@ struct OptMuxtreeWorker
vector<bool> visited_muxes;
};
void eval_mux_port(knowledge_t &knowledge, int mux_idx, int port_idx)
void eval_mux_port(knowledge_t &knowledge, int mux_idx, int port_idx, bool do_replace_known, bool do_enable_ports)
{
muxinfo_t &muxinfo = mux2info[mux_idx];
if (muxinfo.ports[port_idx].const_deactivated)
return;
muxinfo.ports[port_idx].enabled = true;
if (do_enable_ports)
muxinfo.ports[port_idx].enabled = true;
for (int i = 0; i < GetSize(muxinfo.ports); i++) {
if (i == port_idx)
@ -304,8 +306,10 @@ struct OptMuxtreeWorker
parent_muxes.push_back(m);
}
for (int m : parent_muxes)
if (!root_muxes.at(m))
eval_mux(knowledge, m);
if (root_muxes.at(m))
eval_mux(knowledge, m, false, do_enable_ports);
else
eval_mux(knowledge, m, do_replace_known, do_enable_ports);
for (int m : parent_muxes)
knowledge.visited_muxes[m] = false;
@ -325,6 +329,14 @@ struct OptMuxtreeWorker
SigSpec sig = muxinfo.cell->getPort(portname);
bool did_something = false;
int width = 0;
idict<int> ctrl_bits;
if (portname == "\\B")
width = GetSize(muxinfo.cell->getPort("\\A"));
for (int bit : sig2bits(muxinfo.cell->getPort("\\S"), false))
ctrl_bits(bit);
int port_idx = 0, port_off = 0;
vector<int> bits = sig2bits(sig, false);
for (int i = 0; i < GetSize(bits); i++) {
if (bits[i] < 0)
@ -337,6 +349,19 @@ struct OptMuxtreeWorker
sig[i] = State::S1;
did_something = true;
}
if (width) {
if (ctrl_bits.count(bits[i])) {
sig[i] = ctrl_bits.at(bits[i]) == port_idx ? State::S1 : State::S0;
did_something = true;
}
if (++port_off == width)
port_idx++, port_off=0;
} else {
if (ctrl_bits.count(bits[i])) {
sig[i] = State::S0;
did_something = true;
}
}
}
if (did_something) {
@ -346,20 +371,22 @@ struct OptMuxtreeWorker
}
}
void eval_mux(knowledge_t &knowledge, int mux_idx)
void eval_mux(knowledge_t &knowledge, int mux_idx, bool do_replace_known, bool do_enable_ports)
{
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 (do_replace_known) {
replace_known(knowledge, muxinfo, "\\A");
replace_known(knowledge, muxinfo, "\\B");
}
// if there is a constant activated port we just use it
for (int port_idx = 0; port_idx < GetSize(muxinfo.ports); port_idx++)
{
portinfo_t &portinfo = muxinfo.ports[port_idx];
if (portinfo.const_activated) {
eval_mux_port(knowledge, mux_idx, port_idx);
eval_mux_port(knowledge, mux_idx, port_idx, do_replace_known, do_enable_ports);
return;
}
}
@ -370,37 +397,25 @@ struct OptMuxtreeWorker
for (int port_idx = 0; port_idx < GetSize(muxinfo.ports)-1; port_idx++)
{
portinfo_t &portinfo = muxinfo.ports[port_idx];
if (portinfo.const_deactivated)
continue;
if (knowledge.known_active.at(portinfo.ctrl_sig)) {
eval_mux_port(knowledge, mux_idx, port_idx);
eval_mux_port(knowledge, mux_idx, port_idx, do_replace_known, do_enable_ports);
return;
}
}
// compare ports with known_inactive and known_active signals. If the control
// signal of the port is 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.
// eval all ports that could be activated (control signal is not in
// known_inactive or const_deactivated).
for (int port_idx = 0; port_idx < GetSize(muxinfo.ports); port_idx++)
{
portinfo_t &portinfo = muxinfo.ports[port_idx];
if (port_idx < GetSize(muxinfo.ports)-1) {
bool found_non_known_inactive = false;
if (knowledge.known_inactive.at(portinfo.ctrl_sig) == 0)
found_non_known_inactive = true;
if (!found_non_known_inactive)
if (portinfo.const_deactivated)
continue;
if (port_idx < GetSize(muxinfo.ports)-1)
if (knowledge.known_inactive.at(portinfo.ctrl_sig))
continue;
}
bool port_active = true;
for (int i = 0; i < GetSize(muxinfo.ports)-1; i++) {
if (i == port_idx)
continue;
if (knowledge.known_active.at(muxinfo.ports[i].ctrl_sig))
port_active = false;
}
if (port_active)
eval_mux_port(knowledge, mux_idx, port_idx);
eval_mux_port(knowledge, mux_idx, port_idx, do_replace_known, do_enable_ports);
}
}
@ -411,7 +426,7 @@ struct OptMuxtreeWorker
knowledge.known_active.resize(GetSize(bit2info));
knowledge.visited_muxes.resize(GetSize(mux2info));
knowledge.visited_muxes[mux_idx] = true;
eval_mux(knowledge, mux_idx);
eval_mux(knowledge, mux_idx, true, root_enable_muxes.at(mux_idx));
}
};

8
tests/simple/muxtree.v
View file

@ -70,3 +70,11 @@ end
endmodule
// test case for muxtree with select on leaves
module select_leaves(input C, D, output reg Q);
always @(posedge C)
Q <= Q ? Q : D ? 1'b1 : Q;
endmodule