More thorough constant propagation through MUX devices.
This commit is contained in:
steve
parent
86942ac592
commit
a0d69113c3
265
cprop.cc
265
cprop.cc
|
|
@ -17,7 +17,7 @@
|
|||
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
|
||||
*/
|
||||
#ifdef HAVE_CVS_IDENT
|
||||
#ident "$Id: cprop.cc,v 1.47 2004/02/20 18:53:34 steve Exp $"
|
||||
#ident "$Id: cprop.cc,v 1.47.2.1 2005/08/28 19:50:03 steve Exp $"
|
||||
#endif
|
||||
|
||||
# include "config.h"
|
||||
|
|
@ -852,72 +852,246 @@ void cprop_functor::lpm_mux(Design*des, NetMux*obj)
|
|||
if (obj->sel_width() != 1)
|
||||
return;
|
||||
|
||||
/* If the first input is all constant Vz, then replace the
|
||||
NetMux with an array of BUFIF1 devices, with the enable
|
||||
connected to the select input. */
|
||||
NetScope*scope = obj->scope();
|
||||
|
||||
bool flag = true;
|
||||
for (unsigned idx = 0 ; idx < obj->width() ; idx += 1) {
|
||||
if (! obj->pin_Data(idx, 0).nexus()->drivers_constant()) {
|
||||
flag = false;
|
||||
break;
|
||||
}
|
||||
if (obj->pin_Data(idx, 0).nexus()->drivers_constant())
|
||||
continue;
|
||||
if (obj->pin_Data(idx, 1).nexus()->drivers_constant())
|
||||
continue;
|
||||
|
||||
if (obj->pin_Data(idx, 0).nexus()->driven_value() != verinum::Vz) {
|
||||
flag = false;
|
||||
break;
|
||||
}
|
||||
flag = false;
|
||||
}
|
||||
|
||||
if (flag) {
|
||||
NetScope*scope = obj->scope();
|
||||
for (unsigned idx = 0 ; idx < obj->width() ; idx += 1) {
|
||||
NetLogic*tmp = new NetLogic(obj->scope(),
|
||||
if (! flag) {
|
||||
return;
|
||||
}
|
||||
|
||||
/* We know that every slice has at least one constant. Run
|
||||
through the slices again, creating boolean devices to
|
||||
replace the MUX slice. */
|
||||
|
||||
for (unsigned idx = 0 ; idx < obj->width() ; idx += 1) {
|
||||
|
||||
/* If the Sel==0 input is constant Z, make a bufif1. */
|
||||
if (obj->pin_Data(idx, 0).nexus()->drivers_constant()
|
||||
&& obj->pin_Data(idx, 0).nexus()->driven_value()==verinum::Vz) {
|
||||
|
||||
NetLogic*tmp = new NetLogic(scope,
|
||||
scope->local_symbol(),
|
||||
3, NetLogic::BUFIF1);
|
||||
|
||||
connect(obj->pin_Result(idx), tmp->pin(0));
|
||||
connect(obj->pin_Data(idx,1), tmp->pin(1));
|
||||
connect(obj->pin_Sel(0), tmp->pin(2));
|
||||
des->add_node(tmp);
|
||||
continue;
|
||||
}
|
||||
|
||||
count += 1;
|
||||
delete obj;
|
||||
return;
|
||||
}
|
||||
/* If the Sel==1 input is constant Z, make a bufif0. */
|
||||
if (obj->pin_Data(idx, 1).nexus()->drivers_constant()
|
||||
&& obj->pin_Data(idx, 1).nexus()->driven_value()==verinum::Vz) {
|
||||
|
||||
/* If instead the second input is all constant Vz, replace the
|
||||
NetMux with an array of BUFIF0 devices. */
|
||||
flag = true;
|
||||
for (unsigned idx = 0 ; idx < obj->width() ; idx += 1) {
|
||||
if (! obj->pin_Data(idx, 1).nexus()->drivers_constant()) {
|
||||
flag = false;
|
||||
break;
|
||||
}
|
||||
|
||||
if (obj->pin_Data(idx, 1).nexus()->driven_value() != verinum::Vz) {
|
||||
flag = false;
|
||||
break;
|
||||
}
|
||||
}
|
||||
|
||||
if (flag) {
|
||||
NetScope*scope = obj->scope();
|
||||
for (unsigned idx = 0 ; idx < obj->width() ; idx += 1) {
|
||||
NetLogic*tmp = new NetLogic(obj->scope(),
|
||||
NetLogic*tmp = new NetLogic(scope,
|
||||
scope->local_symbol(),
|
||||
3, NetLogic::BUFIF0);
|
||||
|
||||
connect(obj->pin_Result(idx), tmp->pin(0));
|
||||
connect(obj->pin_Data(idx,0), tmp->pin(1));
|
||||
connect(obj->pin_Sel(0), tmp->pin(2));
|
||||
des->add_node(tmp);
|
||||
continue;
|
||||
}
|
||||
|
||||
count += 1;
|
||||
delete obj;
|
||||
return;
|
||||
/* If both inputs are constant, then derive the output
|
||||
from the sel input. */
|
||||
if (obj->pin_Data(idx, 0).nexus()->drivers_constant()
|
||||
&& obj->pin_Data(idx, 1).nexus()->drivers_constant()) {
|
||||
|
||||
verinum::V a = obj->pin_Data(idx, 0).nexus()->driven_value();
|
||||
verinum::V b = obj->pin_Data(idx, 1).nexus()->driven_value();
|
||||
|
||||
if (a == b) {
|
||||
connect(obj->pin_Result(idx), obj->pin_Data(idx,0));
|
||||
continue;
|
||||
}
|
||||
|
||||
if (a == verinum::V0 && b == verinum::V1) {
|
||||
connect(obj->pin_Result(idx), obj->pin_Sel(0));
|
||||
continue;
|
||||
}
|
||||
|
||||
if (a == verinum::V1 && b == verinum::V0) {
|
||||
NetLogic*tmp = new NetLogic(scope,
|
||||
scope->local_symbol(),
|
||||
2, NetLogic::NOT);
|
||||
connect(obj->pin_Result(idx), tmp->pin(0));
|
||||
connect(obj->pin_Sel(0), tmp->pin(1));
|
||||
des->add_node(tmp);
|
||||
continue;
|
||||
}
|
||||
|
||||
/* A==0: Q = B & S */
|
||||
if (a == verinum::V0) {
|
||||
NetLogic*tmp = new NetLogic(scope,
|
||||
scope->local_symbol(),
|
||||
3, NetLogic::AND);
|
||||
connect(obj->pin_Result(idx), tmp->pin(0));
|
||||
connect(obj->pin_Data(idx,1), tmp->pin(1));
|
||||
connect(obj->pin_Sel(0), tmp->pin(2));
|
||||
des->add_node(tmp);
|
||||
continue;
|
||||
}
|
||||
/* B==1: Q = A | S */
|
||||
if (b == verinum::V1) {
|
||||
NetLogic*tmp = new NetLogic(scope,
|
||||
scope->local_symbol(),
|
||||
3, NetLogic::OR);
|
||||
connect(obj->pin_Result(idx), tmp->pin(0));
|
||||
connect(obj->pin_Data(idx,0), tmp->pin(1));
|
||||
connect(obj->pin_Sel(0), tmp->pin(2));
|
||||
des->add_node(tmp);
|
||||
continue;
|
||||
}
|
||||
/* A==1: Q = B & ~S */
|
||||
if (a == verinum::V1) {
|
||||
NetLogic*inv = new NetLogic(scope,
|
||||
scope->local_symbol(),
|
||||
2, NetLogic::NOT);
|
||||
NetNet*invs = new NetNet(scope,
|
||||
scope->local_symbol(),
|
||||
NetNet::TRI, 1);
|
||||
invs->local_flag(true);
|
||||
connect(inv->pin(0), invs->pin(0));
|
||||
connect(inv->pin(1), obj->pin_Sel(0));
|
||||
des->add_node(inv);
|
||||
|
||||
NetLogic*tmp = new NetLogic(scope,
|
||||
scope->local_symbol(),
|
||||
3, NetLogic::AND);
|
||||
connect(obj->pin_Result(idx), tmp->pin(0));
|
||||
connect(obj->pin_Data(idx,1), tmp->pin(1));
|
||||
connect(inv->pin(0), tmp->pin(2));
|
||||
des->add_node(tmp);
|
||||
continue;
|
||||
}
|
||||
/* B==0: Q = A & ~S */
|
||||
if (b == verinum::V0) {
|
||||
NetLogic*inv = new NetLogic(scope,
|
||||
scope->local_symbol(),
|
||||
2, NetLogic::NOT);
|
||||
NetNet*invs = new NetNet(scope,
|
||||
scope->local_symbol(),
|
||||
NetNet::TRI, 1);
|
||||
invs->local_flag(true);
|
||||
connect(inv->pin(0), invs->pin(0));
|
||||
connect(inv->pin(1), obj->pin_Sel(0));
|
||||
des->add_node(inv);
|
||||
|
||||
NetLogic*tmp = new NetLogic(scope,
|
||||
scope->local_symbol(),
|
||||
3, NetLogic::AND);
|
||||
connect(obj->pin_Result(idx), tmp->pin(0));
|
||||
connect(obj->pin_Data(idx,0), tmp->pin(1));
|
||||
connect(inv->pin(0), tmp->pin(2));
|
||||
des->add_node(tmp);
|
||||
continue;
|
||||
}
|
||||
|
||||
assert(0);
|
||||
continue;
|
||||
}
|
||||
|
||||
/* Only the Sel==0 input is constant. The output is a
|
||||
logical combination of the S and B inputs. */
|
||||
|
||||
if (obj->pin_Data(idx, 0).nexus()->drivers_constant()) {
|
||||
|
||||
verinum::V a = obj->pin_Data(idx, 0).nexus()->driven_value();
|
||||
|
||||
/* A==0: Q = B & S */
|
||||
if (a == verinum::V0) {
|
||||
NetLogic*tmp = new NetLogic(scope,
|
||||
scope->local_symbol(),
|
||||
3, NetLogic::AND);
|
||||
connect(obj->pin_Result(idx), tmp->pin(0));
|
||||
connect(obj->pin_Data(idx,1), tmp->pin(1));
|
||||
connect(obj->pin_Sel(0), tmp->pin(2));
|
||||
des->add_node(tmp);
|
||||
continue;
|
||||
}
|
||||
|
||||
/* A==1: Q = B & ~S */
|
||||
if (a == verinum::V1) {
|
||||
NetLogic*inv = new NetLogic(scope,
|
||||
scope->local_symbol(),
|
||||
2, NetLogic::NOT);
|
||||
NetNet*invs = new NetNet(scope,
|
||||
scope->local_symbol(),
|
||||
NetNet::TRI, 1);
|
||||
invs->local_flag(true);
|
||||
connect(inv->pin(0), invs->pin(0));
|
||||
connect(inv->pin(1), obj->pin_Sel(0));
|
||||
des->add_node(inv);
|
||||
|
||||
NetLogic*tmp = new NetLogic(scope,
|
||||
scope->local_symbol(),
|
||||
3, NetLogic::AND);
|
||||
connect(obj->pin_Result(idx), tmp->pin(0));
|
||||
connect(obj->pin_Data(idx,1), tmp->pin(1));
|
||||
connect(inv->pin(0), tmp->pin(2));
|
||||
des->add_node(tmp);
|
||||
continue;
|
||||
}
|
||||
assert(0);
|
||||
}
|
||||
|
||||
/* Only the Sel==1 input is constant. */
|
||||
if (obj->pin_Data(idx, 1).nexus()->drivers_constant()) {
|
||||
|
||||
verinum::V b = obj->pin_Data(idx, 1).nexus()->driven_value();
|
||||
|
||||
/* B==0: Q = A & ~S */
|
||||
if (b == verinum::V0) {
|
||||
NetLogic*inv = new NetLogic(scope,
|
||||
scope->local_symbol(),
|
||||
2, NetLogic::NOT);
|
||||
NetNet*invs = new NetNet(scope,
|
||||
scope->local_symbol(),
|
||||
NetNet::TRI, 1);
|
||||
invs->local_flag(true);
|
||||
connect(inv->pin(0), invs->pin(0));
|
||||
connect(inv->pin(1), obj->pin_Sel(0));
|
||||
des->add_node(inv);
|
||||
|
||||
NetLogic*tmp = new NetLogic(scope,
|
||||
scope->local_symbol(),
|
||||
3, NetLogic::AND);
|
||||
connect(obj->pin_Result(idx), tmp->pin(0));
|
||||
connect(obj->pin_Data(idx,0), tmp->pin(1));
|
||||
connect(inv->pin(0), tmp->pin(2));
|
||||
des->add_node(tmp);
|
||||
continue;
|
||||
}
|
||||
/* B==1: Q = A | S */
|
||||
if (b == verinum::V1) {
|
||||
NetLogic*tmp = new NetLogic(scope,
|
||||
scope->local_symbol(),
|
||||
3, NetLogic::OR);
|
||||
connect(obj->pin_Result(idx), tmp->pin(0));
|
||||
connect(obj->pin_Data(idx,0), tmp->pin(1));
|
||||
connect(obj->pin_Sel(0), tmp->pin(2));
|
||||
des->add_node(tmp);
|
||||
continue;
|
||||
}
|
||||
|
||||
assert(0);
|
||||
}
|
||||
|
||||
assert(0);
|
||||
}
|
||||
|
||||
delete obj;
|
||||
count += 1;
|
||||
}
|
||||
|
||||
/*
|
||||
|
|
@ -1038,6 +1212,9 @@ void cprop(Design*des)
|
|||
|
||||
/*
|
||||
* $Log: cprop.cc,v $
|
||||
* Revision 1.47.2.1 2005/08/28 19:50:03 steve
|
||||
* More thorough constant propagation through MUX devices.
|
||||
*
|
||||
* Revision 1.47 2004/02/20 18:53:34 steve
|
||||
* Addtrbute keys are perm_strings.
|
||||
*
|
||||
|
|
|
|||
Loading…
Reference in New Issue