Add code generator hooks for latches

Add code generator hooks missing from the previous
patches that add latch synthesis support.

NetLatch.cc

@@ -3,6 +3,7 @@
 // Class NetLatch member-function definitions
 
 #include "NetLatch.h" // NetLatch class definition
+#include "target.h" // target_t structure definition
 
 // constructor
 NetLatch::NetLatch( NetScope *scope, perm_string name, unsigned width )
@@ -11,6 +12,11 @@ NetLatch::NetLatch( NetScope *scope, perm_string name, unsigned width )
 {
 } // end NetLatch constructor
 
+unsigned NetLatch::width() const
+{
+  return ( pin_count() - 1U ) / 2U;
+} // end function width
+
 Link &NetLatch::pin_Data( unsigned w )
 {
   unsigned pn = 1 + 2 * w;
@@ -29,3 +35,9 @@ Link &NetLatch::pin_Gate()
 {
   return pin( 0 );
 } // end function pin_Q
+
+bool NetLatch::emit_node( target_t *driverPtr ) const
+{
+  driverPtr->lpm_latch( this );
+  return true;
+} // end function emit_node

NetLatch.h

@@ -18,6 +18,8 @@ class NetLatch : public NetNode
  public:
   NetLatch( NetScope *, perm_string, unsigned );
 
+  unsigned width() const;
+
   Link &pin_Data( unsigned );
   Link &pin_Q( unsigned );
   Link &pin_Gate();
@@ -25,6 +27,8 @@ class NetLatch : public NetNode
   const Link &pin_Data( unsigned ) const;
   const Link &pin_Q( unsigned ) const;
   const Link &pin_Gate() const;
+
+  virtual bool emit_node( target_t * ) const;
 }; // end class NetLatch
 
 #endif

ivl_target.h

@@ -230,6 +230,7 @@ typedef enum ivl_lpm_type_e {
       IVL_LPM_DEMUX  = 16,
       IVL_LPM_DIVIDE = 12,
       IVL_LPM_FF     =  3,
+      IVL_LPM_LATCH  = 17,
       IVL_LPM_MOD    = 13,
       IVL_LPM_MULT   =  4,
       IVL_LPM_MUX    =  5,

synth2.cc

@@ -231,7 +231,6 @@ bool NetAssignBase::synth_async(Design*des, NetScope*scope, bool sync_flag,
 		      }
 
 		    des->add_node( latchPtr );
-		    delete latchPtr;
 		  }
 
 		catch ( bad_alloc &memoryAllocationException )
@@ -1083,7 +1082,7 @@ bool NetCase::synth_async_1hot_(Design*des, NetScope*scope, bool sync_flag,
 /*
  * Handle synthesis for an asynchronous condition statement. If we get
  * here, we know that the CE of a DFF has already been filled, so the
- * condition expression goes to the select of an asynchronous mux.
+ * condition expression goes to the select of an asynchronous mux, unless a latch is inferred in which case it goes to the latch's gate input.
  */
 bool NetCondit::synth_async(Design*des, NetScope*scope, bool sync_flag,
 			    struct sync_accounting_cell*nex_ff,

t-dll-api.cc

@@ -1084,6 +1084,8 @@ extern "C" unsigned ivl_lpm_width(ivl_lpm_t net)
 	  case IVL_LPM_FF:
 	  case IVL_LPM_RAM:
 	    return net->u_.ff.width;
+          case IVL_LPM_LATCH:
+	    return net->u_.latch.width;
 	  case IVL_LPM_DECODE:
 	  case IVL_LPM_MUX:
 	    return net->u_.mux.width;

t-dll.cc

@@ -33,6 +33,9 @@
 #endif
 # include  <stdlib.h>
 
+#include <new> // standard operator new
+using std::bad_alloc;
+
 #if defined(__WIN32__)
 
 inline ivl_dll_t ivl_dlopen(const char *name)
@@ -1734,6 +1737,30 @@ void dll_target::lpm_ff(const NetFF*net)
       }
 }
 
+void dll_target::lpm_latch( const NetLatch *latchPtr )
+{
+  try
+    {
+      ivl_lpm_s *objPtr = new ivl_lpm_s;
+      objPtr->type = IVL_LPM_LATCH;
+      objPtr->name = latchPtr->name();
+      objPtr->scope = find_scope( des_, latchPtr->scope() );
+      assert( objPtr->scope ); // C++ programmers prefer using exceptions rather than assertions.
+
+      objPtr->u_.latch.width = latchPtr->width();
+
+      objPtr->nattr = latchPtr->attr_cnt();
+      objPtr->attr = fill_in_attributes( latchPtr );
+
+      scope_add_lpm( objPtr->scope, objPtr );
+    }
+  catch ( bad_alloc &memoryAllocationException )
+    {
+      cerr << "Exception occurred: " << memoryAllocationException.what() << endl;
+    }
+
+} // end function lpm_latch
+
 void dll_target::lpm_ram_dq(const NetRamDq*net)
 {
       ivl_memory_t mem = find_memory(des_, net->mem());

t-dll.h

@@ -80,6 +80,7 @@ struct dll_target  : public target_t, public expr_scan_t {
       bool lpm_demux(const NetDemux*);
       void lpm_divide(const NetDivide*);
       void lpm_ff(const NetFF*);
+      void lpm_latch( const NetLatch * );
       void lpm_modulo(const NetModulo*);
       void lpm_mult(const NetMult*);
       void lpm_mux(const NetMux*);
@@ -328,6 +329,10 @@ struct ivl_lpm_s {
 		  ivl_expr_t sset_value;
 	    } ff;
 
+	    struct ivl_lpm_latch_s {
+	      unsigned width;
+	    } latch;
+
 	    struct ivl_lpm_mux_s {
 		  unsigned width;
 		  unsigned size;

target.cc

@@ -133,6 +133,11 @@ void target_t::lpm_ff(const NetFF*)
 	    "Unhandled NetFF." << endl;
 }
 
+void target_t::lpm_latch( const NetLatch * )
+{
+      cerr << "target (" << typeid( *this ).name() << "): Unhandled NetLatch." << endl;
+}
+
 void target_t::lpm_mult(const NetMult*)
 {
       cerr << "target (" << typeid(*this).name() << "): "

target.h

@@ -23,6 +23,7 @@
 #endif
 
 # include  "netlist.h"
+#include "NetLatch.h"
 
 /*
  * This header file describes the types and constants used to describe
@@ -84,6 +85,7 @@ struct target_t {
       virtual void lpm_divide(const NetDivide*);
       virtual void lpm_modulo(const NetModulo*);
       virtual void lpm_ff(const NetFF*);
+      virtual void lpm_latch( const NetLatch * );
       virtual void lpm_mult(const NetMult*);
       virtual void lpm_mux(const NetMux*);
       virtual void lpm_ram_dq(const NetRamDq*);