On Wed, Sep 23, 2015 at 08:55:53PM +0200, Bernd Schmidt wrote:
> On 09/23/2015 06:07 PM, Marek Polacek wrote:
> >Given that the code above seems to be useless now, I think let's put this
> >patch in as-is, backport it to gcc-5, then remove those redundant hunks on
> >trunk and add the testcase above. Do you agree?
>
> Sounds reasonable. If you can find a point in the history where that code
> wasn't useless, it would be good to help us understand why it's there.
I did some archeology. The code wasn't useless since it was added (r211859)
till r226110 where I added some unshare_exprs. On the testcase I posted
earlier in the thread that makes a difference:
@@ -11,7 +11,7 @@
else
{
<<< Unknown tree: void_cst >>>
- }, (long unsigned int) (s->a[i] << SAVE_EXPR <i>);;
+ }, (long unsigned int) (s->a[UBSAN_BOUNDS (0B, SAVE_EXPR <i>, 0);,
SAVE_EXPR <i>;] << SAVE_EXPR <i>);;
}
So we instrument the array multiple times as it's not shared anymore.
Ok to proceed with the plan I mentioned above?
Marek
