[pypy-commit] pypy default: Issue #2750

[arigo]

Author: Armin Rigo <arigo at tunes.org>
Branch: 
Changeset: r93803:7eaba44b228a
Date: 2018-02-11 20:52 +0100
http://bitbucket.org/pypy/pypy/changeset/7eaba44b228a/

Log:	Issue #2750

	Speed up array.__setslice__() for arguments that are changing the
	size of the array, but in such a way that it's just an
	array.extend().

diff --git a/pypy/module/array/interp_array.py b/pypy/module/array/interp_array.py
--- a/pypy/module/array/interp_array.py
+++ b/pypy/module/array/interp_array.py
@@ -1090,12 +1090,16 @@
             start, stop, step, size = self.space.decode_index4(w_idx, self.len)
             assert step != 0
             if w_item.len != size or self is w_item:
-                # XXX this is a giant slow hack
-                w_lst = self.descr_tolist(space)
-                w_item = space.call_method(w_item, 'tolist')
-                space.setitem(w_lst, w_idx, w_item)
-                self.setlen(0)
-                self.fromsequence(w_lst)
+                if start == self.len and step > 0:
+                    # we actually want simply extend()
+                    self.extend(w_item)
+                else:
+                    # XXX this is a giant slow hack
+                    w_lst = self.descr_tolist(space)
+                    w_item = space.call_method(w_item, 'tolist')
+                    space.setitem(w_lst, w_idx, w_item)
+                    self.setlen(0)
+                    self.fromsequence(w_lst)
             else:
                 j = 0
                 buf = self.get_buffer()
diff --git a/pypy/module/array/test/test_array.py b/pypy/module/array/test/test_array.py
--- a/pypy/module/array/test/test_array.py
+++ b/pypy/module/array/test/test_array.py
@@ -267,6 +267,12 @@
         b = self.array('u', u'hi')
         assert len(b) == 2 and b[0] == 'h' and b[1] == 'i'
 
+    def test_setslice_to_extend(self):
+        a = self.array('i')
+        a[0:1] = self.array('i', [9])
+        a[1:5] = self.array('i', [99])
+        assert list(a) == [9, 99]
+
     def test_sequence(self):
         a = self.array('i', [1, 2, 3, 4])
         assert len(a) == 4