On Mon, Apr 22, 2013 at 05:23:17PM +0100, Richard Henderson wrote:
> On 2013-04-22 17:21, Jakub Jelinek wrote:
> >On Mon, Apr 22, 2013 at 06:11:26PM +0200, Marek Polacek wrote:
> >>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 <pola...@redhat.com>
> >>
> >> PR sanitizer/56990
> >> * tsan.c (instrument_expr): Don't count modulo if the size
> >> is zero.
> >>
> >> * gcc.dg/pr56990.c: New test.
> >>
> >>--- 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
> >
> >IMHO for size == 0 we should return false too, there is no store or read to
> >be instrumented. So
> > if (size == 0
> > || bitpos % (size * BITS_PER_UNIT)
> > || bitsize != size * BITS_PER_UNIT)
> > return false;
> >?
>
> Point. And along those lines, will we ever have bitsize == 0?
> If not, then just swapping the conditions is sufficient:
Well, actually the bitsize is 0 in this case, so only swapping the
conditions wouldn't suffice. So this is what Jakub suggested and
also my first version of the patch ;).
Ok?
2013-04-22 Marek Polacek <pola...@redhat.com>
PR sanitizer/56990
* tsan.c (instrument_expr): Don't instrument expression
in case its size is zero.
* gcc.dg/pr56990.c: New test.
--- gcc/tsan.c.mp 2013-04-19 15:39:46.416450528 +0200
+++ gcc/tsan.c 2013-04-22 18:49:57.834052631 +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){};
+}
m~
