From a2477208c8bb94fe109f46b30d77d60276dfebe2 Mon Sep 17 00:00:00 2001
From: Victor Stinner <victor.stinner@haypocalc.com>
Date: Mon, 30 Jan 2012 00:07:43 +0100
Subject: Issue #13874: read_null() of faulthandler uses volatile to avoid
 optimisation

Clang 3.0 removes "y = *x;" instruction if the optimisation level is 3.
---
 Modules/faulthandler.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/Modules/faulthandler.c b/Modules/faulthandler.c
index fcf4d01..f18bbbc 100644
--- a/Modules/faulthandler.c
+++ b/Modules/faulthandler.c
@@ -943,10 +943,13 @@ faulthandler_unregister_py(PyObject *self, PyObject *args)
 static PyObject *
 faulthandler_read_null(PyObject *self, PyObject *args)
 {
-    int *x = NULL, y;
+    volatile int *x;
+    volatile int y;
     int release_gil = 0;
     if (!PyArg_ParseTuple(args, "|i:_read_null", &release_gil))
         return NULL;
+
+    x = NULL;
     if (release_gil) {
         Py_BEGIN_ALLOW_THREADS
         y = *x;
-- 
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