vector: Implement hash cache for vector3d and vector

this gives us a small runtime improvement in the router.

For FreePDK45 word_size=8, num_words=256

Improved
*** Maze routing supplies: 89.8 seconds
** Routing: 279.3 seconds

Non-improved
*** Maze routing supplies: 105.1 seconds
** Routing: 293.5 seconds

Signed-off-by: Bastian Koppelmann <kbastian@mail.uni-paderborn.de>

compiler/base/vector.py

@@ -28,6 +28,7 @@ class vector():
         else:
             self.x = float(x)
             self.y = float(y)
+        self._hash = hash((self.x,self.y))
 
     def __str__(self):
         """ override print function output """
@@ -97,7 +98,7 @@ class vector():
         Note: This assumes that you DON'T CHANGE THE VECTOR or it will
         break things.
         """
-        return hash((self.x,self.y))
+        return self._hash
 
     def snap_to_grid(self):
         self.x = self.snap_offset_to_grid(self.x)

compiler/router/vector3d.py

@@ -27,7 +27,7 @@ class vector3d():
             self.x = x
             self.y = y
             self.z = z
-
+        self._hash = hash((self.x,self.y,self.z))
             
     def __str__(self):
         """ override print function output """
@@ -96,7 +96,7 @@ class vector3d():
         Note: This assumes that you DON'T CHANGE THE VECTOR or it will
         break things.
         """
-        return hash((self.x,self.y,self.z))
+        return self._hash
 
 
     def __rsub__(self, other):