Issue #16674: random.getrandbits() is now 20-40% faster for small integers.

serhiy-storchaka · serhiy-storchaka · commit d8a0bac8f761 · 2013-01-04T12:18:35.000+02:00
diff --git a/Misc/NEWS b/Misc/NEWS
@@ -201,6 +201,8 @@ Core and Builtins
 Library
 -------
 
+- Issue #16674: random.getrandbits() is now 20-40% faster for small integers.
+
 - Issue #16009: JSON error messages now provide more information.
 
 - Issue #16828: Fix error incorrectly raised by bz2.compress(b'') and
diff --git a/Modules/_randommodule.c b/Modules/_randommodule.c
@@ -360,6 +360,9 @@ random_getrandbits(RandomObject *self, PyObject *args)
         return NULL;
     }
 
+    if (k <= 32)  /* Fast path */
+        return PyLong_FromUnsignedLong(genrand_int32(self) >> (32 - k));
+
     bytes = ((k - 1) / 32 + 1) * 4;
     bytearray = (unsigned char *)PyMem_Malloc(bytes);
     if (bytearray == NULL) {

Original file line number	Diff line number	Diff line change
`@@ -360,6 +360,9 @@ random_getrandbits(RandomObject self, PyObject args)`
`360`	`360`	`return NULL;`
`361`	`361`	`}`
`362`	`362`
	`363`	`+ if (k <= 32) /* Fast path */`
	`364`	`+ return PyLong_FromUnsignedLong(genrand_int32(self) >> (32 - k));`
	`365`	`+`
`363`	`366`	`bytes = ((k - 1) / 32 + 1) * 4;`
`364`	`367`	`bytearray = (unsigned char *)PyMem_Malloc(bytes);`
`365`	`368`	`if (bytearray == NULL) {`