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Add extmodule support to firrtl backend

Browse source 
The current firrtl backend emits blackboxes as standard modules
with an empty body, but this causes the firrtl compiler to
optimize out entire circuits due to the absence of any drivers.

Yosys already tags blackboxes with a (*blackbox*) attribute, so this
commit just propagates this change to firrtl's syntax for blackboxes.
This commit is contained in:
Sahand Kashani 2020-05-06 01:01:14 +02:00
parent 283b1130a6
commit 1f1b64b880
1 changed files with 47 additions and 1 deletions
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48
backends/firrtl/firrtl.cc
View file

@ -392,7 +392,37 @@ struct FirrtlWorker
return result;
}
void run()
void emit_extmodule()
{
std::string moduleFileinfo = getFileinfo(module);
f << stringf(" extmodule %s: %s\n", make_id(module->name), moduleFileinfo.c_str());
vector<string> port_decls;
for (auto wire : module->wires())
{
const auto wireName = make_id(wire->name);
std::string wireFileinfo = getFileinfo(wire);
// Maybe not needed?
if (wire->port_id)
{
if (wire->port_input && wire->port_output)
{
log_error("Module port %s.%s is inout!\n", log_id(module), log_id(wire));
}
port_decls.push_back(stringf(" %s %s: UInt<%d> %s\n", wire->port_input ? "input" : "output",
wireName, wire->width, wireFileinfo.c_str()));
}
}
for (auto str : port_decls) {
f << str;
}
f << stringf("\n");
}
void emit_module()
{
std::string moduleFileinfo = getFileinfo(module);
f << stringf(" module %s: %s\n", make_id(module->name), moduleFileinfo.c_str());
@ -1076,6 +1106,22 @@ struct FirrtlWorker
for (auto str : wire_exprs)
f << str;
f << stringf("\n");
}
void run()
{
// Blackboxes should be emitted as `extmodule`s in firrtl. Only ports are
// emitted in such a case.
if (module->get_blackbox_attribute())
{
emit_extmodule();
}
else
{
emit_module();
}
}
};