[pypy-svn] pypy default: Don't generate nonsense for UNPACK_ITERABLE with a non-{list, tuple} item (specifically array)

[alex_gaynor]

Author: Alex Gaynor <alex.gaynor at gmail.com>
Branch: 
Changeset: r42990:6e681c7a274f
Date: 2011-03-27 19:21 -0400
http://bitbucket.org/pypy/pypy/changeset/6e681c7a274f/

Log:	Don't generate nonsense for UNPACK_ITERABLE with a non-{list,tuple}
	item (specifically array)

diff --git a/pypy/module/pypyjit/test_pypy_c/model.py b/pypy/module/pypyjit/test_pypy_c/model.py
--- a/pypy/module/pypyjit/test_pypy_c/model.py
+++ b/pypy/module/pypyjit/test_pypy_c/model.py
@@ -260,7 +260,7 @@
     @classmethod
     def is_const(cls, v1):
         return isinstance(v1, str) and v1.startswith('ConstClass(')
-    
+
     def match_var(self, v1, exp_v2):
         assert v1 != '_'
         if exp_v2 == '_':
@@ -287,7 +287,7 @@
         for arg, exp_arg in zip(op.args, exp_args):
             self._assert(self.match_var(arg, exp_arg), "variable mismatch: %r instead of %r" % (arg, exp_arg))
         self.match_descr(op.descr, exp_descr)
-        
+
 
     def _next_op(self, iter_ops, assert_raises=False):
         try:

diff --git a/pypy/interpreter/baseobjspace.py b/pypy/interpreter/baseobjspace.py
--- a/pypy/interpreter/baseobjspace.py
+++ b/pypy/interpreter/baseobjspace.py
@@ -754,7 +754,12 @@
         """Unpack an iterable object into a real (interpreter-level) list.
         Raise an OperationError(w_ValueError) if the length is wrong."""
         w_iterator = self.iter(w_iterable)
-        items = []
+        # If we know the expected length we can preallocate.
+        if expected_length == -1:
+            items = []
+        else:
+            items = [None] * expected_length
+        idx = 0
         while True:
             try:
                 w_item = self.next(w_iterator)
@@ -762,19 +767,22 @@
                 if not e.match(self, self.w_StopIteration):
                     raise
                 break  # done
-            if expected_length != -1 and len(items) == expected_length:
+            if expected_length != -1 and idx == expected_length:
                 raise OperationError(self.w_ValueError,
                                      self.wrap("too many values to unpack"))
-            items.append(w_item)
-        if expected_length != -1 and len(items) < expected_length:
-            i = len(items)
-            if i == 1:
+            if expected_length == -1:
+                items.append(w_item)
+            else:
+                items[idx] = w_item
+            idx += 1
+        if expected_length != -1 and idx < expected_length:
+            if idx == 1:
                 plural = ""
             else:
                 plural = "s"
             raise OperationError(self.w_ValueError,
                       self.wrap("need more than %d value%s to unpack" %
-                                (i, plural)))
+                                (idx, plural)))
         return items
 
     unpackiterable_unroll = jit.unroll_safe(func_with_new_name(unpackiterable,

diff --git a/pypy/module/pypyjit/test_pypy_c/test_pypy_c_new.py b/pypy/module/pypyjit/test_pypy_c/test_pypy_c_new.py
--- a/pypy/module/pypyjit/test_pypy_c/test_pypy_c_new.py
+++ b/pypy/module/pypyjit/test_pypy_c/test_pypy_c_new.py
@@ -1036,3 +1036,36 @@
             --TICK--
             jump(p0, p1, p2, p3, p4, i21, i6, i7, p8, p9, descr=<Loop0>)
         """)
+
+    def test_unpack_iterable_non_list_tuple(self):
+        def main(n):
+            import array
+
+            items = [array.array("i", [1])] * n
+            total = 0
+            for a, in items:
+                total += a
+            return total
+
+        log = self.run(main, [1000000])
+        assert log.result == 1000000
+        loop, = log.loops_by_filename(self.filepath)
+        assert loop.match("""
+            i16 = int_ge(i12, i13)
+            guard_false(i16, descr=<Guard3>)
+            p17 = getarrayitem_gc(p15, i12, descr=<GcPtrArrayDescr>)
+            i19 = int_add(i12, 1)
+            setfield_gc(p4, i19, descr=<SignedFieldDescr .*W_AbstractSeqIterObject.inst_index .*>)
+            guard_nonnull_class(p17, 146982464, descr=<Guard4>)
+            i21 = getfield_gc(p17, descr=<SignedFieldDescr .*W_ArrayTypei.inst_len .*>)
+            i23 = int_lt(0, i21)
+            guard_true(i23, descr=<Guard5>)
+            i24 = getfield_gc(p17, descr=<NonGcPtrFieldDescr .*W_ArrayTypei.inst_buffer .*>)
+            i25 = getarrayitem_raw(i24, 0, descr=<SignedArrayNoLengthDescr>)
+            i27 = int_lt(1, i21)
+            guard_false(i27, descr=<Guard6>)
+            i28 = int_add_ovf(i10, i25)
+            guard_no_overflow(descr=<Guard7>)
+            --TICK--
+            jump(p0, p1, p2, p3, p4, p5, p6, p7, p8, p9, i28, i25, i19, i13, p14, p15, descr=<Loop0>)
+        """)
\ No newline at end of file