[Python-checkins] cpython: Since the index is always non-negative, use faster unsigned division and modulo.

[raymond.hettinger]

https://hg.python.org/cpython/rev/91a1613e161c
changeset:   94780:91a1613e161c
user:        Raymond Hettinger <python at rcn.com>
date:        Fri Feb 27 12:42:54 2015 -0800
summary:
  Since the index is always non-negative, use faster unsigned division and modulo.

files:
  Modules/_collectionsmodule.c |  8 +++++---
  1 files changed, 5 insertions(+), 3 deletions(-)


diff --git a/Modules/_collectionsmodule.c b/Modules/_collectionsmodule.c
--- a/Modules/_collectionsmodule.c
+++ b/Modules/_collectionsmodule.c
@@ -142,7 +142,7 @@
 
 static PyTypeObject deque_type;
 
-/* XXX Todo: 
+/* XXX Todo:
    If aligned memory allocations become available, make the
    deque object 64 byte aligned so that all of the fields
    can be retrieved or updated in a single cache line.
@@ -780,7 +780,9 @@
         b = deque->rightblock;
     } else {
         i += deque->leftindex;
-        n = i / BLOCKLEN;
+        assert(i >= 0);
+        n = (Py_ssize_t)((unsigned) i / BLOCKLEN);
+        i = (Py_ssize_t)((unsigned) i % BLOCKLEN);
         i %= BLOCKLEN;
         if (index < (Py_SIZE(deque) >> 1)) {
             b = deque->leftblock;
@@ -1848,7 +1850,7 @@
                 (hash = ((PyASCIIObject *) key)->hash) == -1)
             {
                 hash = PyObject_Hash(key);
-                if (hash == -1) 
+                if (hash == -1)
                     goto done;
             }
 

-- 
Repository URL: https://hg.python.org/cpython