riscv
/
yosys
mirror of https://github.com/YosysHQ/yosys.git
1
0
Fork 0
Code Issues Projects Releases Wiki Activity

Some improvements in opt_rmdff

This commit is contained in:
Clifford Wolf 2013-05-23 07:48:18 +02:00
parent 63e6a35ce2
commit 3b8882ae49
1 changed files with 33 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

33
passes/opt/opt_rmdff.cc
View File

@ -25,6 +25,7 @@
#include <stdio.h>
static SigMap assign_map;
static SigSet<RTLIL::Cell*> mux_drivers;
static bool handle_dff(RTLIL::Module *mod, RTLIL::Cell *dff)
{
@ -72,13 +73,36 @@ static bool handle_dff(RTLIL::Module *mod, RTLIL::Cell *dff)
assign_map.apply(sig_c);
assign_map.apply(sig_r);
if (dff->type == "$dff" && mux_drivers.has(sig_d)) {
std::set<RTLIL::Cell*> muxes;
mux_drivers.find(sig_d, muxes);
for (auto mux : muxes) {
RTLIL::SigSpec sig_a = assign_map(mux->connections.at("\\A"));
RTLIL::SigSpec sig_b = assign_map(mux->connections.at("\\B"));
if (sig_a == sig_q && sig_b.is_fully_const()) {
RTLIL::SigSig conn(sig_q, sig_b);
mod->connections.push_back(conn);
goto delete_dff;
}
if (sig_b == sig_q && sig_a.is_fully_const()) {
RTLIL::SigSig conn(sig_q, sig_a);
mod->connections.push_back(conn);
goto delete_dff;
}
}
}
if (sig_d.is_fully_const() && sig_r.width == 0) {
RTLIL::SigSig conn(sig_q, sig_d);
mod->connections.push_back(conn);
goto delete_dff;
}
if (sig_d == sig_q && sig_r.width == 0) {
if (sig_d == sig_q) {
if (sig_r.width > 0) {
RTLIL::SigSig conn(sig_q, val_rv);
mod->connections.push_back(conn);
}
goto delete_dff;
}
@ -117,9 +141,15 @@ struct OptRmdffPass : public Pass {
continue;
assign_map.set(mod_it.second);
mux_drivers.clear();
std::vector<std::string> dff_list;
for (auto &it : mod_it.second->cells) {
if (it.second->type == "$mux" || it.second->type == "$pmux") {
if (it.second->connections.at("\\A").width == it.second->connections.at("\\B").width)
mux_drivers.insert(assign_map(it.second->connections.at("\\Y")), it.second);
continue;
}
if (!design->selected(mod_it.second, it.second))
continue;
if (it.second->type == "$_DFF_N_") dff_list.push_back(it.first);
@ -144,6 +174,7 @@ struct OptRmdffPass : public Pass {
}
assign_map.clear();
mux_drivers.clear();
log("Replaced %d DFF cells.\n", total_count);
}
} OptRmdffPass;