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Use NetReplicate to implement replication for concat 

Currently replication in a concatenation is implemented by simply
concatenating the input signals multiple times by the replication amount.

Replace this to use NetReplicate on the concatenation instead. In case
there is only one input vector to the concatenation the replication will directly
connect to the input vector.

This is slightly more efficient in vvp since the replication functor has
only one input while the concatenation has multiple inputs connected to the
same wire. When an update of the input occurs the replication functor will
only receive a single update, while the concatenation will receive multiple
update events, one for each replication.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
This commit is contained in:
Lars-Peter Clausen 2024-01-03 21:43:07 -08:00
parent 60864ff1c7
commit 2d22f43ba7
1 changed files with 46 additions and 21 deletions
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67
expr_synth.cc
View File

@ -776,23 +776,24 @@ NetNet* NetEConcat::synthesize(Design*des, NetScope*scope, NetExpr*root)
return 0;
}
/* Make a NetNet object to carry the output vector. */
perm_string path = scope->local_symbol();
netvector_t*osig_vec = new netvector_t(data_type, expr_width()-1, 0);
NetNet*osig = new NetNet(scope, path, NetNet::IMPLICIT, osig_vec);
osig->set_line(*this);
osig->local_flag(true);
NetNet *osig = nullptr;
NetConcat*cncat = new NetConcat(scope, scope->local_symbol(),
osig->vector_width(),
num_parms * repeat());
cncat->set_line(*this);
des->add_node(cncat);
connect(cncat->pin(0), osig->pin(0));
if (num_parms != 1) {
/* Make a NetNet object to carry the output vector. */
auto osig_vec = new netvector_t(data_type, expr_width() / repeat() - 1, 0);
osig = new NetNet(scope, scope->local_symbol(), NetNet::IMPLICIT,
osig_vec);
osig->set_line(*this);
osig->local_flag(true);
unsigned count_input_width = 0;
unsigned cur_pin = 1;
for (unsigned rpt = 0; rpt < repeat(); rpt += 1) {
auto cncat = new NetConcat(scope, scope->local_symbol(),
osig->vector_width(), num_parms);
cncat->set_line(*this);
des->add_node(cncat);
connect(cncat->pin(0), osig->pin(0));
unsigned count_input_width = 0;
unsigned cur_pin = 1;
for (unsigned idx = 0 ; idx < parms_.size() ; idx += 1) {
unsigned concat_item = parms_.size()-idx-1;
if (tmp[concat_item] == 0) continue;
@ -800,14 +801,38 @@ NetNet* NetEConcat::synthesize(Design*des, NetScope*scope, NetExpr*root)
cur_pin += 1;
count_input_width += tmp[concat_item]->vector_width();
}
if (count_input_width != osig->vector_width()) {
cerr << get_fileline() << ": internal error: "
<< "NetEConcat input width = " << count_input_width
<< ", expecting " << osig->vector_width()
<< endl;
des->errors += 1;
}
} else {
/* There is exactly one input signal */
for (unsigned idx = 0; idx < parms_.size(); idx++) {
if (tmp[idx]) {
osig = tmp[idx];
break;
}
}
ivl_assert(*this, osig);
}
if (count_input_width != osig->vector_width()) {
cerr << get_fileline() << ": internal error: "
<< "NetEConcat input width = " << count_input_width
<< ", expecting " << osig->vector_width()
<< " (repeat=" << repeat() << ")" << endl;
des->errors += 1;
if (repeat() != 1) {
auto rep = new NetReplicate(scope, scope->local_symbol(),
expr_width(), repeat());
rep->set_line(*this);
des->add_node(rep);
connect(rep->pin(1), osig->pin(0));
auto osig_vec = new netvector_t(data_type, expr_width() - 1, 0);
osig = new NetNet(scope, scope->local_symbol(), NetNet::IMPLICIT,
osig_vec);
osig->set_line(*this);
osig->local_flag(true);
connect(rep->pin(0), osig->pin(0));
}
delete[]tmp;