OK.
On Thu, Mar 1, 2018 at 9:14 AM, Marek Polacek <pola...@redhat.com> wrote:
> Here we were using pow2align as the right operand of <<. But for invalid
> alignments pow2align can be -1 which makes the shifting invalid. Fixed by
> moving the checking before using pow2align.
>
> Bootstrapped/regtested on x86_64-linux, ok for trunk?
>
> 2018-03-01 Marek Polacek <pola...@redhat.com>
>
> PR c++/84639
> * c-attribs.c (common_handle_aligned_attribute): Don't use invalid
> alignment in computation.
>
> diff --git gcc/c-family/c-attribs.c gcc/c-family/c-attribs.c
> index 0261a45ec98..3ebb2d6000c 100644
> --- gcc/c-family/c-attribs.c
> +++ gcc/c-family/c-attribs.c
> @@ -1817,6 +1817,12 @@ common_handle_aligned_attribute (tree *node, tree
> name, tree args, int flags,
>
> /* Log2 of specified alignment. */
> int pow2align = check_user_alignment (align_expr, true);
> + if (pow2align == -1
> + || !check_cxx_fundamental_alignment_constraints (*node, pow2align,
> flags))
> + {
> + *no_add_attrs = true;
> + return NULL_TREE;
> + }
>
> /* The alignment in bits corresponding to the specified alignment. */
> unsigned bitalign = (1U << pow2align) * BITS_PER_UNIT;
> @@ -1826,10 +1832,7 @@ common_handle_aligned_attribute (tree *node, tree
> name, tree args, int flags,
> unsigned curalign = 0;
> unsigned lastalign = 0;
>
> - if (pow2align == -1
> - || !check_cxx_fundamental_alignment_constraints (*node, pow2align,
> flags))
> - *no_add_attrs = true;
> - else if (is_type)
> + if (is_type)
> {
> if ((flags & (int) ATTR_FLAG_TYPE_IN_PLACE))
> /* OK, modify the type in place. */;
>
> Marek
