From patchwork Mon Apr 22 16:11:26 2013
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Subject: Fix PR56990
From: Marek Polacek <polacek@redhat.com>
X-Patchwork-Id: 238607
Message-Id: <20130422161126.GH13346@redhat.com>
To: GCC Patches <gcc-patches@gcc.gnu.org>
Date: Mon, 22 Apr 2013 18:11:26 +0200

We're getting SIGFPE, because one simply does not divide by zero.
Fixed by doing the modulo only when size != 0.

Regtested/bootstrapped on x86_64-linux, ok for trunk and 4.8?

2013-04-22  Marek Polacek  <polacek@redhat.com>

	PR sanitizer/56990
	* tsan.c (instrument_expr): Don't count modulo if the size
	is zero.

	* gcc.dg/pr56990.c: New test.


	Marek

--- gcc/tsan.c.mp	2013-04-19 15:39:46.416450528 +0200
+++ gcc/tsan.c	2013-04-22 17:23:54.115647673 +0200
@@ -131,7 +131,8 @@ instrument_expr (gimple_stmt_iterator gs
   if (TREE_READONLY (base))
     return false;
 
-  if (bitpos % (size * BITS_PER_UNIT)
+  if ((size != 0
+       && bitpos % (size * BITS_PER_UNIT))
       || bitsize != size * BITS_PER_UNIT)
     return false;
 
--- gcc/testsuite/gcc.dg/pr56990.c.mp	2013-04-22 17:30:14.523876683 +0200
+++ gcc/testsuite/gcc.dg/pr56990.c	2013-04-22 17:29:06.704666252 +0200
@@ -0,0 +1,10 @@
+/* PR sanitizer/56990 */
+/* { dg-do compile { target { x86_64-*-linux* && lp64 } } } */
+/* { dg-options "-fsanitize=thread" } */
+
+struct S{};
+
+void foo(struct S *p)
+{
+  *p = (struct S){};
+}