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Rewrite the cprop functor to use the functor_t interface.

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1 parent 65ae928 commit 4de8ba489de6f144f8de252244b83d46cbf2b800 steve committed Dec 17, 1999
Showing with 142 additions and 115 deletions.
  1. +96 −111 cprop.cc
  2. +8 −1 expr_synth.cc
  3. +22 −1 functor.cc
  4. +10 −1 functor.h
  5. +6 −1 netlist.h
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207 cprop.cc
@@ -17,137 +17,122 @@
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
*/
#if !defined(WINNT)
-#ident "$Id: cprop.cc,v 1.3 1999/12/17 03:38:46 steve Exp $"
+#ident "$Id: cprop.cc,v 1.4 1999/12/17 06:18:15 steve Exp $"
#endif
# include "netlist.h"
+# include "functor.h"
# include <assert.h>
/*
- * The cprop function below invokes constant propogation where
- * possible. The elaboration generates NetConst objects. I can remove
- * these and replace the gates connected to it with simpler ones. I
- * may even be able to replace nets with a new constant.
+ * This local function returns true if all the the possible drivers of
+ * this link are constant. It will also return true if there are no
+ * drivers at all.
*/
-
-static bool is_a_const_node(const NetNode*obj)
+static bool all_drivers_constant(const NetObj::Link&lnk)
{
- return dynamic_cast<const NetConst*>(obj);
-}
+ for (const NetObj::Link*cur = lnk.next_link()
+ ; *cur != lnk ; cur = cur->next_link()) {
-static bool const_into_xnor(Design*des, verinum::V cval,
- NetLogic*log, unsigned pin)
-{
- assert(pin > 0);
-
- /* if this is the last input pin of the XNOR device, then
- the device is simply buffering the constant value. */
- if (log->pin_count() == 2) {
- cerr << "cprop: delete gate " << log->name() <<
- " and propogate " << cval << "." << endl;
-
- assert(pin == 1);
- connect(log->pin(0), log->pin(1));
-
- delete log;
- return true;
+ if (cur->get_dir() == NetObj::Link::INPUT)
+ continue;
+ if (cur->get_dir() == NetObj::Link::PASSIVE)
+ continue;
+ if (! dynamic_cast<const NetConst*>(cur->get_obj()))
+ return false;
}
- /* If this is a constant 0, then replace the gate with one
- 1-pin smaller. Skip this pin. */
- if (cval == verinum::V0) {
- cerr << "cprop: disconnect pin " << pin << " from gate "
- << log->name() << "." << endl;
-
- NetLogic*tmp = new NetLogic(log->name(),
- log->pin_count()-1,
- NetLogic::XNOR);
- connect(log->pin(0), tmp->pin(0));
- unsigned idx, jdx;
- for (idx = 1, jdx = 1 ; idx < log->pin_count() ; idx += 1) {
- if (idx == pin) continue;
- connect(log->pin(idx), tmp->pin(jdx));
- jdx += 1;
- }
+ return true;
+}
+
+/*
+ * This function returns the value of the constant driving this link,
+ * or Vz if there is no constant. The results of this function are
+ * only meaningful if all_drivers_constant(lnk) == true.
+ */
+static verinum::V driven_value(const NetObj::Link&lnk)
+{
+ for (const NetObj::Link*cur = lnk.next_link()
+ ; *cur != lnk ; cur = cur->next_link()) {
- delete log;
- des->add_node(tmp);
- return true;
+ const NetConst*obj;
+ if (obj = dynamic_cast<const NetConst*>(cur->get_obj()))
+ return obj->value(cur->get_pin());
}
- /* If this is a constant 1, then replace the gate with an XOR
- that is 1-pin smaller. Removing the constant 1 causes the
- sense of the output to change. */
- if (cval == verinum::V1) {
- cerr << "cprop: disconnect pin " << pin << " from gate "
- << log->name() << "." << endl;
-
- NetLogic*tmp = new NetLogic(log->name(),
- log->pin_count()-1,
- NetLogic::XOR);
- connect(log->pin(0), tmp->pin(0));
- unsigned idx, jdx;
- for (idx = 1, jdx = 1 ; idx < log->pin_count() ; idx += 1) {
- if (idx == pin) continue;
- connect(log->pin(idx), tmp->pin(jdx));
- jdx += 1;
- }
+ return verinum::Vz;
+}
- delete log;
- des->add_node(tmp);
- return true;
- }
+/*
+ * The cprop function below invokes constant propogation where
+ * possible. The elaboration generates NetConst objects. I can remove
+ * these and replace the gates connected to it with simpler ones. I
+ * may even be able to replace nets with a new constant.
+ */
- /* If this is a constant X or Z, then the gate is certain to
- generate an X. Replace the gate with a constant X. This may
- cause other signals all over to become dangling. */
- if ((cval == verinum::Vx) || (cval == verinum::Vz)) {
- cerr << "cprop: replace gate " << log->name() << " with "
- "a constant X." << endl;
-
- NetConst*tmp = new NetConst(log->name(), verinum::Vx);
- connect(log->pin(0), tmp->pin(0));
- delete log;
- des->add_node(tmp);
- return true;
- }
+struct cprop_functor : public functor_t {
- return false;
-}
+ virtual void lpm_logic(Design*des, NetLogic*obj);
+};
-static void look_for_core_logic(Design*des, NetConst*obj, unsigned cpin)
+void cprop_functor::lpm_logic(Design*des, NetLogic*obj)
{
- NetObj*cur = obj;
- unsigned pin = 0;
- for (obj->pin(cpin).next_link(cur, pin)
- ; cur != obj
- ; cur->pin(pin).next_link(cur, pin)) {
-
- NetLogic*log = dynamic_cast<NetLogic*>(cur);
- if (log == 0)
- continue;
+ switch (obj->type()) {
+
+ case NetLogic::AND:
+ // If there is one zero input to an AND gate, we know
+ // the resulting output is going to be zero and can
+ // elininate the gate.
+ for (unsigned idx = 1 ; idx < obj->pin_count() ; idx += 1) {
+ if (! all_drivers_constant(obj->pin(idx)))
+ continue;
+ if (driven_value(obj->pin(idx)) == verinum::V0) {
+ connect(obj->pin(0), obj->pin(idx));
+ delete obj;
+ return;
+ }
+ }
- bool flag = false;
- switch (log->type()) {
- case NetLogic::XNOR:
- flag = const_into_xnor(des, obj->value(cpin), log, pin);
- break;
- default:
- break;
+ // There are no zero constant drivers. If there are any
+ // non-constant drivers, give up.
+ for (unsigned idx = 1 ; idx < obj->pin_count() ; idx += 1) {
+ if (! all_drivers_constant(obj->pin(idx)))
+ return;
}
- /* If the optimization test tells me that a link was
- deleted, restart the scan. */
- if (flag) obj->pin(0).next_link(cur, pin);
+ // If there are any non-1 values (Vx or Vz) then the
+ // result is Vx.
+ for (unsigned idx = 1 ; idx < obj->pin_count() ; idx += 1) {
+ if (driven_value(obj->pin(idx)) != verinum::V1) {
+ connect(obj->pin(0), obj->pin(idx));
+ delete obj;
+ return;
+ }
+ }
+
+ // What's left? The inputs are all 1's, return the first
+ // input as the output value and remove the gate.
+ connect(obj->pin(0), obj->pin(1));
+ delete obj;
+ return;
+
+ default:
+ break;
}
}
/*
- * This function looks to see if the constant is connected to nothing
+ * This functor looks to see if the constant is connected to nothing
* but signals. If that is the case, delete the dangling constant and
- * the now useless signals.
+ * the now useless signals. This functor is applied after the regular
+ * functor to clean up dangling constants that might be left behind.
*/
-static void dangling_const(Design*des, NetConst*obj)
+struct cprop_dc_functor : public functor_t {
+
+ virtual void lpm_const(Design*des, NetConst*obj);
+};
+
+void cprop_dc_functor::lpm_const(Design*des, NetConst*obj)
{
// If there are any links that take input, abort this
// operation.
@@ -175,21 +160,21 @@ static void dangling_const(Design*des, NetConst*obj)
delete obj;
}
+
void cprop(Design*des)
{
- des->clear_node_marks();
- while (NetNode*obj = des->find_node(&is_a_const_node)) {
- NetConst*cur = dynamic_cast<NetConst*>(obj);
- for (unsigned idx = 0 ; idx < cur->pin_count() ; idx += 1)
- look_for_core_logic(des, cur, idx);
- cur->set_mark();
- dangling_const(des, cur);
- }
+ cprop_functor prop;
+ des->functor(&prop);
+ cprop_dc_functor dc;
+ des->functor(&dc);
}
/*
* $Log: cprop.cc,v $
+ * Revision 1.4 1999/12/17 06:18:15 steve
+ * Rewrite the cprop functor to use the functor_t interface.
+ *
* Revision 1.3 1999/12/17 03:38:46 steve
* NetConst can now hold wide constants.
*
View
9 expr_synth.cc
@@ -17,7 +17,7 @@
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
*/
#if !defined(WINNT)
-#ident "$Id: expr_synth.cc,v 1.7 1999/12/17 03:38:46 steve Exp $"
+#ident "$Id: expr_synth.cc,v 1.8 1999/12/17 06:18:15 steve Exp $"
#endif
# include "netlist.h"
@@ -83,6 +83,7 @@ NetNet* NetEBBits::synthesize(Design*des)
assert(lsig->pin_count() == rsig->pin_count());
NetNet*osig = new NetNet(0, path, NetNet::IMPLICIT, lsig->pin_count());
+ osig->local_flag(true);
for (unsigned idx = 0 ; idx < osig->pin_count() ; idx += 1) {
string oname = des->local_symbol(path);
@@ -125,6 +126,7 @@ NetNet* NetEConst::synthesize(Design*des)
unsigned width=expr_width();
NetNet*osig = new NetNet(0, path, NetNet::IMPLICIT, width);
+ osig->local_flag(true);
NetConst*con = new NetConst(des->local_symbol(path), value());
for (unsigned idx = 0 ; idx < width; idx += 1)
connect(osig->pin(idx), con->pin(idx));
@@ -144,6 +146,7 @@ NetNet* NetEUBits::synthesize(Design*des)
NetNet*isig = expr_->synthesize(des);
NetNet*osig = new NetNet(0, path, NetNet::IMPLICIT, isig->pin_count());
+ osig->local_flag(true);
for (unsigned idx = 0 ; idx < osig->pin_count() ; idx += 1) {
string oname = des->local_symbol(path);
@@ -178,6 +181,7 @@ NetNet* NetETernary::synthesize(Design *des)
assert(tsig->pin_count() == fsig->pin_count());
unsigned width=tsig->pin_count();
NetNet*osig = new NetNet(0, path, NetNet::IMPLICIT, width);
+ osig->local_flag(true);
string oname = des->local_symbol(path);
NetMux *mux = new NetMux(oname, width, 2, 1);
@@ -199,6 +203,9 @@ NetNet* NetESignal::synthesize(Design*des)
/*
* $Log: expr_synth.cc,v $
+ * Revision 1.8 1999/12/17 06:18:15 steve
+ * Rewrite the cprop functor to use the functor_t interface.
+ *
* Revision 1.7 1999/12/17 03:38:46 steve
* NetConst can now hold wide constants.
*
View
23 functor.cc
@@ -17,7 +17,7 @@
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
*/
#if !defined(WINNT)
-#ident "$Id: functor.cc,v 1.6 1999/12/05 02:24:08 steve Exp $"
+#ident "$Id: functor.cc,v 1.7 1999/12/17 06:18:16 steve Exp $"
#endif
# include "functor.h"
@@ -35,10 +35,18 @@ void functor_t::process(class Design*, class NetProcTop*)
{
}
+void functor_t::lpm_const(class Design*, class NetConst*)
+{
+}
+
void functor_t::lpm_ff(class Design*, class NetFF*)
{
}
+void functor_t::lpm_logic(class Design*, class NetLogic*)
+{
+}
+
void Design::functor(functor_t*fun)
{
// apply to signals
@@ -75,11 +83,21 @@ void NetNode::functor_node(Design*, functor_t*)
{
}
+void NetConst::functor_node(Design*des, functor_t*fun)
+{
+ fun->lpm_const(des, this);
+}
+
void NetFF::functor_node(Design*des, functor_t*fun)
{
fun->lpm_ff(des, this);
}
+void NetLogic::functor_node(Design*des, functor_t*fun)
+{
+ fun->lpm_logic(des, this);
+}
+
proc_match_t::~proc_match_t()
{
}
@@ -131,6 +149,9 @@ int NetPEvent::match_proc(proc_match_t*that)
/*
* $Log: functor.cc,v $
+ * Revision 1.7 1999/12/17 06:18:16 steve
+ * Rewrite the cprop functor to use the functor_t interface.
+ *
* Revision 1.6 1999/12/05 02:24:08 steve
* Synthesize LPM_RAM_DQ for writes into memories.
*
View
11 functor.h
@@ -19,7 +19,7 @@
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
*/
#if !defined(WINNT)
-#ident "$Id: functor.h,v 1.4 1999/12/05 02:24:08 steve Exp $"
+#ident "$Id: functor.h,v 1.5 1999/12/17 06:18:16 steve Exp $"
#endif
/*
@@ -42,8 +42,14 @@ struct functor_t {
/* This method is called for each process in the design. */
virtual void process(class Design*des, class NetProcTop*);
+ /* This method is called for each structural constant. */
+ virtual void lpm_const(class Design*des, class NetConst*);
+
/* This method is called for each FF in the design. */
virtual void lpm_ff(class Design*des, class NetFF*);
+
+ /* Handle LPM combinational logic devices. */
+ virtual void lpm_logic(class Design*des, class NetLogic*);
};
struct proc_match_t {
@@ -58,6 +64,9 @@ struct proc_match_t {
/*
* $Log: functor.h,v $
+ * Revision 1.5 1999/12/17 06:18:16 steve
+ * Rewrite the cprop functor to use the functor_t interface.
+ *
* Revision 1.4 1999/12/05 02:24:08 steve
* Synthesize LPM_RAM_DQ for writes into memories.
*
View
7 netlist.h
@@ -19,7 +19,7 @@
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
*/
#if !defined(WINNT)
-#ident "$Id: netlist.h,v 1.103 1999/12/17 03:38:46 steve Exp $"
+#ident "$Id: netlist.h,v 1.104 1999/12/17 06:18:16 steve Exp $"
#endif
/*
@@ -725,6 +725,7 @@ class NetConst : public NetNode {
verinum::V value(unsigned idx) const;
virtual void emit_node(ostream&, struct target_t*) const;
+ virtual void functor_node(Design*, functor_t*);
virtual void dump_node(ostream&, unsigned ind) const;
private:
@@ -747,6 +748,7 @@ class NetLogic : public NetNode {
virtual void dump_node(ostream&, unsigned ind) const;
virtual void emit_node(ostream&, struct target_t*) const;
+ virtual void functor_node(Design*, functor_t*);
private:
const TYPE type_;
@@ -2078,6 +2080,9 @@ extern ostream& operator << (ostream&, NetNet::Type);
/*
* $Log: netlist.h,v $
+ * Revision 1.104 1999/12/17 06:18:16 steve
+ * Rewrite the cprop functor to use the functor_t interface.
+ *
* Revision 1.103 1999/12/17 03:38:46 steve
* NetConst can now hold wide constants.
*

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