allow interconnect annotations without forks

src/kyupy/sdf.py

@@ -103,6 +103,7 @@ class DelayFile:
 
         delays = np.zeros((len(circuit.lines), 2, 2, 3))  # dataset last during construction.
 
+        nonfork_annotations = 0
         for n1, n2, *delvals in self._interconnects:
             delvals = [d if len(d) > 0 else [0, 0, 0] for d in delvals]
             if max(max(delvals)) == 0: continue
@@ -120,19 +121,27 @@ class DelayFile:
                 log.warn(f'No line to annotate pin {pn2} of {c2}')
                 continue
             f1, f2 = c1.outs[p1].reader, c2.ins[p2].driver  # find the forks between cells.
+            if f1 == c2 and f2 == c1:
+                nonfork_annotations += 1
+                if nonfork_annotations < 10:
+                    log.warn(f'No fork between {c1.name}/{p1} and {c2.name}/{p2}, using {c2.name}/{p2}')
+                line = c2.ins[p2]
+            else:
                 assert f1.kind == '__fork__'
                 assert f2.kind == '__fork__'
-            if f1 != f2:  # at least two forks, make sure f2 is a branchfork connected to f1
+                if len(f2.outs) == 1:
-                assert len(f2.outs) == 1
+                    assert f1 == f2 or f1.outs[f2.ins[0].driver_pin] == f2.ins[0]
-                assert f1.outs[f2.ins[0].driver_pin] == f2.ins[0]
-                line = f2.ins[0]
-            elif len(f2.outs) == 1:  # f1==f2, only OK when there is no fanout.
                     line = f2.ins[0]
                 else:
-                log.warn(f'No branchfork to annotate interconnect delay {c1.name}/{p1}->{c2.name}/{p2}')
+                    nonfork_annotations += 1
-                continue
+                    if nonfork_annotations < 10:
+                        log.warn(f'No branchfork between {c1.name}/{p1} and {c2.name}/{p2}, using {c2.name}/{p2}')
+                    line = c2.ins[p2]
             delays[line, :] = delvals
 
+        if nonfork_annotations > 0:
+            log.warn(f'{nonfork_annotations} interconnect annotations were moved to gate inputs due to missing forks.')
+
         return np.moveaxis(delays, -1, 0)