Author: Carl Friedrich Bolz <[email protected]>
Branch: improve-heap-caching-tracing
Changeset: r47023:3dbbdca31951
Date: 2011-09-02 15:25 +0200
http://bitbucket.org/pypy/pypy/changeset/3dbbdca31951/
Log: add some helpful comments
diff --git a/pypy/jit/metainterp/heapcache.py b/pypy/jit/metainterp/heapcache.py
--- a/pypy/jit/metainterp/heapcache.py
+++ b/pypy/jit/metainterp/heapcache.py
@@ -63,12 +63,20 @@
self.heap_cache.setdefault(descr, {})[box] = fieldbox
def setfield(self, box, descr, fieldbox):
+ # slightly subtle logic here
d = self.heap_cache.get(descr, None)
new_d = {box: fieldbox}
+ # a write to an arbitrary box, all other boxes can alias this one
if not d or box not in self.new_boxes:
+ # therefore we throw away the cache
self.heap_cache[descr] = new_d
return
+ # the object we are writing to is freshly allocated
+ # only remove some boxes from the cache
for frombox, tobox in d.iteritems():
+ # the other box is *also* freshly allocated
+ # therefore frombox and box *must* contain different objects
+ # thus we can keep it in the cache
if frombox in self.new_boxes:
new_d[frombox] = tobox
self.heap_cache[descr] = new_d
_______________________________________________
pypy-commit mailing list
[email protected]
http://mail.python.org/mailman/listinfo/pypy-commit
