New subject: [pypy-commit] pypy default: Unroll list.count() when the list is virtual or very small and constant lenght

30 Aug 2013

Hi Alex,

please revert this change, it can lead to combinatorial explosion: it
can give a bridge per pattern of where in the list the object is found.

Cheers,

Carl Friedrich

On 29/08/13 23:47, alex_gaynor wrote:
...
Author: Alex Gaynor 
Branch: 
Changeset: r66432:185512e0c4df
Date: 2013-08-29 15:47 -0700
http://bitbucket.org/pypy/pypy/changeset/185512e0c4df/
Log:	Unroll list.count() when the list is virtual or very small and
  constant lenght

diff --git a/pypy/module/pypyjit/test_pypy_c/test_containers.py b/pypy/module/pypyjit/test_pypy_c/test_containers.py
--- a/pypy/module/pypyjit/test_pypy_c/test_containers.py
+++ b/pypy/module/pypyjit/test_pypy_c/test_containers.py
@@ -241,3 +241,22 @@
         loop, = log.loops_by_filename(self.filepath)
         ops = loop.ops_by_id('getitem', include_guard_not_invalidated=False)
         assert log.opnames(ops) == []
+
+    def test_list_count_virtual_list(self):
+        def main(n):
+            i = 0
+            while i < n:
+                i += [n].count(n)
+            return i
+
+        log = self.run(main, [1000])
+        assert log.result == main(1000)
+        loop, = log.loops_by_filename(self.filepath)
+        assert loop.match("""
+            i7 = int_lt(i5, i6)
+            guard_true(i7, descr=...)
+            guard_not_invalidated(descr=...)
+            i9 = int_add(i5, 1)
+            --TICK--
+            jump(..., descr=...)
+        """)
diff --git a/pypy/objspace/std/listobject.py b/pypy/objspace/std/listobject.py
--- a/pypy/objspace/std/listobject.py
+++ b/pypy/objspace/std/listobject.py
@@ -562,6 +562,8 @@
         'L.reverse() -- reverse *IN PLACE*'
         self.reverse()
+    @jit.look_inside_iff(lambda self, space, w_value:
+            jit.loop_unrolling_heuristic(self, self.length(), UNROLL_CUTOFF))
     def descr_count(self, space, w_value):
         '''L.count(value) -> integer -- return number of
         occurrences of value'''
_______________________________________________
pypy-commit mailing list
pypy-commit@python.org
http://mail.python.org/mailman/listinfo/pypy-commit


    

Re: [pypy-dev] [pypy-commit] pypy default: Unroll list.count() when the list is virtual or very small and constant lenght

Carl Friedrich Bolz

Amaury Forgeot d'Arc

Carl Friedrich Bolz

Alex Gaynor

Carl Friedrich Bolz

Alex Gaynor

tags

participants (3)