[PATCH] Don't fold zero-sized elements (PR c/58346)

Richard Biener richard.guenther@gmail.com
Fri Jan 17 14:37:00 GMT 2014


On Fri, Jan 17, 2014 at 2:37 PM, Marek Polacek <polacek@redhat.com> wrote:
> This is the real fix for PR58346.  I'd say the easiest solution is
> just not fold the zero-sized elements.
>
> Bootstrapped/regtested on x86_64-linux, ok for trunk?

Ok.

Thanks,
Richard.

> 2014-01-17  Marek Polacek  <polacek@redhat.com>
>
>         PR c/58346
>         * gimple-fold.c (fold_array_ctor_reference): Don't fold if element
>         size is zero.
> testsuite/
>         * gcc.dg/pr58346.c: New test.
>
> --- gcc/gimple-fold.c.mp2       2014-01-17 12:03:56.149446880 +0100
> +++ gcc/gimple-fold.c   2014-01-17 12:04:00.450462677 +0100
> @@ -2940,7 +2940,8 @@ fold_array_ctor_reference (tree type, tr
>       be larger than size of array element.  */
>    if (!TYPE_SIZE_UNIT (type)
>        || TREE_CODE (TYPE_SIZE_UNIT (type)) != INTEGER_CST
> -      || elt_size.slt (tree_to_double_int (TYPE_SIZE_UNIT (type))))
> +      || elt_size.slt (tree_to_double_int (TYPE_SIZE_UNIT (type)))
> +      || elt_size.is_zero ())
>      return NULL_TREE;
>
>    /* Compute the array index we look for.  */
> --- gcc/testsuite/gcc.dg/pr58346.c.mp2  2014-01-17 12:27:26.180127058 +0100
> +++ gcc/testsuite/gcc.dg/pr58346.c      2014-01-17 12:28:20.466332046 +0100
> @@ -0,0 +1,19 @@
> +/* PR tree-optimization/58346 */
> +/* { dg-do compile } */
> +/* { dg-options "-O" } */
> +
> +struct U {};
> +static struct U b[1] = { };
> +extern void bar (struct U);
> +
> +void
> +foo (void)
> +{
> +  bar (b[0]);
> +}
> +
> +void
> +baz (void)
> +{
> +  foo ();
> +}
>
>         Marek



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