Try routing in larger regions if no path is found

compiler/router/graph.py

@@ -111,7 +111,7 @@ class graph:
         return False
 
 
-    def create_graph(self, source, target):
+    def create_graph(self, source, target, scale=1):
         """ Create the graph to run routing on later. """
         debug.info(2, "Creating the graph for source '{}' and target'{}'.".format(source, target))
 
@@ -122,6 +122,7 @@ class graph:
         # Find the region to be routed and only include objects inside that region
         region = deepcopy(source)
         region.bbox([target])
+        region.multiply(scale)
         region = region.inflated_pin(spacing=self.router.track_space)
         debug.info(3, "Routing region is {}".format(region.rect))
 
@@ -147,6 +148,9 @@ class graph:
         debug.info(3, "Number of vias detected in the routing region: {}".format(len(self.graph_vias)))
         debug.info(3, "Number of nodes in the routing graph: {}".format(len(self.nodes)))
 
+        # Return the region to scale later if no path is found
+        return region.rect
+
 
     def find_graph_blockages(self, region):
         """ Find blockages that overlap the routing region. """

compiler/router/graph_router.py

@@ -96,20 +96,35 @@ class graph_router(router_tech):
             pins = self.pins[pin_name]
             # Route closest pins according to the minimum spanning tree
             for source, target in self.get_mst_pairs(list(pins)):
-                # Create the graph
-                g = graph(self)
-                g.create_graph(source, target)
-                # Find the shortest path from source to target
-                path = g.find_shortest_path()
-                # TODO: Exponentially increase the routing area and retry if no
-                # path was found
-                debug.check(path is not None, "Couldn't route from {} to {}".format(source, target))
-                # Create the path shapes on layout
-                self.add_path(path)
-                # Find the recently added shapes
-                self.prepare_gds_reader()
-                self.find_blockages(pin_name)
-                self.find_vias()
+                # This is the routing region scale
+                scale = 1
+                while True:
+                    # Create the graph
+                    g = graph(self)
+                    region = g.create_graph(source, target, scale)
+                    # Find the shortest path from source to target
+                    path = g.find_shortest_path()
+                    # If there is no path found, exponentially try again with a
+                    # larger routing region
+                    if path is None:
+                        rll, rur = region
+                        bll, bur = self.ring_bbox
+                        # Stop scaling the region and throw an error
+                        if rll.x < bll.x and rll.y < bll.y and \
+                           rur.x > bur.x and rur.y > bur.y:
+                            self.write_debug_gds(gds_name="{}error.gds".format(OPTS.openram_temp), g=g, source=source, target=target)
+                            debug.error("Couldn't route from {} to {}.".format(source, target), -1)
+                        # Exponentially scale the region
+                        scale *= 2
+                        debug.info(0, "Retry routing in larger routing region with scale {}".format(scale))
+                        continue
+                    # Create the path shapes on layout
+                    self.add_path(path)
+                    # Find the recently added shapes
+                    self.prepare_gds_reader()
+                    self.find_blockages(pin_name)
+                    self.find_vias()
+                    break
 
 
     def prepare_gds_reader(self):

compiler/router/graph_shape.py

@@ -65,6 +65,17 @@ class graph_shape(pin_layout):
         return graph_shape(self.name, inflated_area, self.layer, self)
 
 
+    def multiply(self, scale):
+        """ Multiply the width and height with the scale value. """
+
+        width = (self.width() * (scale - 1)) / 2
+        height = (self.height() * (scale - 1)) / 2
+        ll, ur = self.rect
+        newll = vector(ll.x - width, ll.y - height)
+        newur = vector(ur.x + width, ur.y + height)
+        self.rect = [snap(newll), snap(newur)]
+
+
     def aligns(self, other):
         """ Return if the other shape aligns with this shape. """