[pypy-commit] pypy default: Mark sys.defaultencoding as quassi-immutable, this removes a guard + call to streq any time you do a str->unicode conversion.

[alex_gaynor]

Author: Alex Gaynor <alex.gaynor at gmail.com>
Branch: 
Changeset: r45029:500f3cbaf027
Date: 2011-06-20 11:42 -0700
http://bitbucket.org/pypy/pypy/changeset/500f3cbaf027/

Log:	Mark sys.defaultencoding as quassi-immutable, this removes a guard +
	call to streq any time you do a str->unicode conversion.

diff --git a/pypy/module/pypyjit/test_pypy_c/test_string.py b/pypy/module/pypyjit/test_pypy_c/test_string.py
new file mode 100644
--- /dev/null
+++ b/pypy/module/pypyjit/test_pypy_c/test_string.py
@@ -0,0 +1,42 @@
+from pypy.module.pypyjit.test_pypy_c.test_00_model import BaseTestPyPyC
+
+class TestString(BaseTestPyPyC):
+    def test_lookup_default_encoding(self):
+        def main(n):
+            import string
+            i = 0
+            letters = string.letters
+            uletters = unicode(string.letters)
+            while i < n:
+                i += letters[i % len(letters)] == uletters[i % len(letters)]
+            return i
+
+        log = self.run(main, [300])
+        assert log.result == 300
+        loop, = log.loops_by_filename(self.filepath)
+        assert loop.match("""
+            i14 = int_lt(i6, i9)
+            guard_true(i14, descr=<Guard42>)
+            i15 = int_mod(i6, i10)
+            i17 = int_rshift(i15, 63)
+            i18 = int_and(i10, i17)
+            i19 = int_add(i15, i18)
+            i21 = int_lt(i19, 0)
+            guard_false(i21, descr=<Guard43>)
+            i22 = int_ge(i19, i10)
+            guard_false(i22, descr=<Guard44>)
+            i23 = strgetitem(p11, i19)
+            i24 = int_ge(i19, i12)
+            guard_false(i24, descr=<Guard45>)
+            i25 = unicodegetitem(p13, i19)
+            guard_not_invalidated(descr=<Guard46>)
+            p27 = newstr(1)
+            strsetitem(p27, 0, i23)
+            p30 = call(ConstClass(ll_str2unicode__rpy_stringPtr), p27, descr=<GcPtrCallDescr>)
+            guard_no_exception(descr=<Guard47>)
+            i32 = call(ConstClass(_ll_2_str_eq_checknull_char__rpy_unicodePtr_UniChar), p30, i25, descr=<SignedCallDescr>)
+            guard_true(i32, descr=<Guard48>)
+            i34 = int_add(i6, 1)
+            --TICK--
+            jump(p0, p1, p2, p3, p4, p5, i34, p7, p8, i9, i10, p11, i12, p13, descr=<Loop4>)
+        """)
\ No newline at end of file
diff --git a/pypy/module/sys/__init__.py b/pypy/module/sys/__init__.py
--- a/pypy/module/sys/__init__.py
+++ b/pypy/module/sys/__init__.py
@@ -7,6 +7,8 @@
 
 class Module(MixedModule):
     """Sys Builtin Module. """
+    _immutable_fields_ = ["defaultencoding?"]
+
     def __init__(self, space, w_name):
         """NOT_RPYTHON""" # because parent __init__ isn't
         if space.config.translating: