Fix unchecked use of tree_to_uhwi in tree-ssa-strlen.c

[Richard Biener]

On Fri, Oct 11, 2019 at 4:47 PM Richard Sandiford
<richard.sandiford@arm.com> wrote:
>
> r273783 introduced an unchecked use of tree_to_uhwi.  This is
> tested by the SVE ACLE patches, but could potentially trigger
> in non-SVE cases too.
>
> Tested on aarch64-linux-gnu and x86_64-linux-gnu.  OK to install?

OK.

Richard.

> Richard
>
>
> 2019-10-11  Richard Sandiford  <richard.sandiford@arm.com>
>
> gcc/
>         * tree-ssa-strlen.c (count_nonzero_bytes): Check tree_fits_uhwi_p
>         before using tree_to_uhwi.
>
> Index: gcc/tree-ssa-strlen.c
> ===================================================================
> --- gcc/tree-ssa-strlen.c       2019-10-11 15:43:51.127514545 +0100
> +++ gcc/tree-ssa-strlen.c       2019-10-11 15:46:11.718524445 +0100
> @@ -4026,10 +4026,10 @@ count_nonzero_bytes (tree exp, unsigned
>
>        /* The size of the MEM_REF access determines the number of bytes.  */
>        tree type = TREE_TYPE (exp);
> -      if (tree typesize = TYPE_SIZE_UNIT (type))
> -       nbytes = tree_to_uhwi (typesize);
> -      else
> +      tree typesize = TYPE_SIZE_UNIT (type);
> +      if (!typesize || !tree_fits_uhwi_p (typesize))
>         return false;
> +      nbytes = tree_to_uhwi (typesize);
>
>        /* Handle MEM_REF = SSA_NAME types of assignments.  */
>        return count_nonzero_bytes (arg, offset, nbytes, lenrange, nulterm,