[pypy-svn] r73735 - in pypy/branch/blackhole-improvement/pypy/tool/algo: . test

[arigo at codespeak.net]

Author: arigo
Date: Wed Apr 14 14:04:22 2010
New Revision: 73735

Modified:
   pypy/branch/blackhole-improvement/pypy/tool/algo/color.py
   pypy/branch/blackhole-improvement/pypy/tool/algo/test/test_color.py
Log:
Find an optimal graph coloring.  The result is not optimal with respect
to the number of copies potentially needed, though.



Modified: pypy/branch/blackhole-improvement/pypy/tool/algo/color.py
==============================================================================
--- pypy/branch/blackhole-improvement/pypy/tool/algo/color.py	(original)
+++ pypy/branch/blackhole-improvement/pypy/tool/algo/color.py	Wed Apr 14 14:04:22 2010
@@ -1,9 +1,4 @@
 """
-the whole algorithm is based on the following paper:
-http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.86.1578&rep=rep1&type=pdf
-
-and the source code of libFIRM (file ir/be/becopyheur.c):
-http://pp.info.uni-karlsruhe.de/firm/Main_Page
 """
 
 
@@ -58,13 +53,18 @@
             seen.add(v)
         return result
 
-
-##class Unit(object):
-##    """An optimization unit.  Represents a phi instruction."""
-##    def __init__(self, result, args):
-##        self.result = result
-##        self.args = args
-
-##    def optimize(self, depgraph):
-##        self.queue = []
-##        self.insert_qnode(QNode(...
+    def find_node_coloring(self):
+        """Return a random minimal node coloring, assuming that
+        the graph is chordal."""
+        result = {}
+        for v in self.lexicographic_order():
+            forbidden = 0      # bitset
+            for n in self.neighbours[v]:
+                if n in result:
+                    forbidden |= (1 << result[n])
+            # find the lowest 0 bit
+            num = 0
+            while forbidden & (1 << num):
+                num += 1
+            result[v] = num
+        return result

Modified: pypy/branch/blackhole-improvement/pypy/tool/algo/test/test_color.py
==============================================================================
--- pypy/branch/blackhole-improvement/pypy/tool/algo/test/test_color.py	(original)
+++ pypy/branch/blackhole-improvement/pypy/tool/algo/test/test_color.py	Wed Apr 14 14:04:22 2010
@@ -25,3 +25,10 @@
         'cabde', 'cabed', 'cadbe', 'cadeb', 'caebd', 'caedb',
         ]
     assert dg.size_of_largest_clique() == 3
+    coloring = dg.find_node_coloring()
+    assert len(coloring) == 5
+    assert sorted(coloring.keys()) == list('abcde')
+    assert set(coloring.values()) == set([0, 1, 2])
+    for v1, v2list in dg.neighbours.items():
+        for v2 in v2list:
+            assert coloring[v1] != coloring[v2]