From: Andrew Waterman <waterman@cs.berkeley.edu>
Date: Wed, 21 Jan 2015 17:20:05 +0000 (+0000)
Subject: Avoid misaligned atomic operations
X-Git-Tag: releases/gcc-4.8.5~316
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=15e148898ed542391a6f164717031ae8bcbeb405;p=thirdparty%2Fgcc.git

Avoid misaligned atomic operations

 Andrew Waterman <waterman@cs.berkeley.edu>

 * fop_n.c (libat_fetch_op): Align address to word boundary.
 (libat_op_fetch): Likewise.

From-SVN: r219956
---

diff --git a/libatomic/ChangeLog b/libatomic/ChangeLog
index 1630dc0d84c7..858b6ea89606 100644
--- a/libatomic/ChangeLog
+++ b/libatomic/ChangeLog
@@ -1,3 +1,8 @@
+2015-01-21  Andrew Waterman <waterman@cs.berkeley.edu>
+
+	* fop_n.c (libat_fetch_op): Align address to word boundary.
+	(libat_op_fetch): Likewise.
+
 2014-12-19  Release Manager
 
 	* GCC 4.8.4 released.
diff --git a/libatomic/fop_n.c b/libatomic/fop_n.c
index 5e4b224aa5a4..2328e52e6d1a 100644
--- a/libatomic/fop_n.c
+++ b/libatomic/fop_n.c
@@ -112,9 +112,9 @@ SIZE(C2(libat_fetch_,NAME)) (UTYPE *mptr, UTYPE opval, int smodel)
 
   pre_barrier (smodel);
 
-  wptr = (UWORD *)mptr;
-  shift = 0;
-  mask = -1;
+  wptr = (UWORD *)((uintptr_t)mptr & -WORDSIZE);
+  shift = (((uintptr_t)mptr % WORDSIZE) * CHAR_BIT) ^ SIZE(INVERT_MASK);
+  mask = SIZE(MASK) << shift;
 
   wopval = (UWORD)opval << shift;
   woldval = __atomic_load_n (wptr, __ATOMIC_RELAXED);
@@ -136,9 +136,9 @@ SIZE(C3(libat_,NAME,_fetch)) (UTYPE *mptr, UTYPE opval, int smodel)
 
   pre_barrier (smodel);
 
-  wptr = (UWORD *)mptr;
-  shift = 0;
-  mask = -1;
+  wptr = (UWORD *)((uintptr_t)mptr & -WORDSIZE);
+  shift = (((uintptr_t)mptr % WORDSIZE) * CHAR_BIT) ^ SIZE(INVERT_MASK);
+  mask = SIZE(MASK) << shift;
 
   wopval = (UWORD)opval << shift;
   woldval = __atomic_load_n (wptr, __ATOMIC_RELAXED);