Re: [RFA][PATCH] Don't use wi->info to pass gimple location to array warning callbacks in tree-vrp.c

[Richard Biener <richard dot guenther at gmail dot com>]

On Wed, Oct 25, 2017 at 7:30 PM, Jeff Law <law@redhat.com> wrote:
>
> The array dereference warnings in tree-vrp.c use the gimple walkers to
> dig down into gimple statements looking for array accesses.  I wasn't
> keen to convert all the clients of the gimple walkers to C++ classes at
> this time.
>
> And the gimple walkers have a mechanism by which we could pass around a
> class instance -- they've got an opaque pointer (wi->info).
>
> THe pointer is already in use to hold a gimple location.  So I initially
> thought I'd have to instead have it point to a structure that would hold
> the gimple location and a class instance.
>
> However, we can get to the gimple location via other means -- we can
> just extract it from the gimple statement which is a first class entity
> within the wi structure.  That's all this patch does.
>
>
> That frees up the opaque pointer and in a future patch I can just shove
> the vr_values class instance into it.
>
> Bootstrapped and regression tested on x86_64.
>
> OK for the trunk?

OK.  The user probably was introduced before the stmt field in
walk_stmt_info.

Thanks,
Richard.

> Jeff
>
> ps.  Now to figure out a strategy for vrp_valueize, which are the last
> callbacks that need fixing to allow encapsulation of the vr_values bits.
>
>
>         * tree-vrp.c (check_all_array_refs): Do not use wi->info to smuggle
>         gimple statement locations.
>         (check_array_bounds): Corresponding changes.  Get the statement's
>         location directly from wi->stmt.
>
>
> diff --git a/gcc/tree-vrp.c b/gcc/tree-vrp.c
> index 2bc485c..9defbce 100644
> --- a/gcc/tree-vrp.c
> +++ b/gcc/tree-vrp.c
> @@ -6837,10 +6837,7 @@ check_array_bounds (tree *tp, int *walk_subtree, void *data)
>    if (EXPR_HAS_LOCATION (t))
>      location = EXPR_LOCATION (t);
>    else
> -    {
> -      location_t *locp = (location_t *) wi->info;
> -      location = *locp;
> -    }
> +    location = gimple_location (wi->stmt);
>
>    *walk_subtree = TRUE;
>
> @@ -6887,9 +6884,6 @@ check_all_array_refs (void)
>
>           memset (&wi, 0, sizeof (wi));
>
> -         location_t loc = gimple_location (stmt);
> -         wi.info = &loc;
> -
>           walk_gimple_op (gsi_stmt (si),
>                           check_array_bounds,
>                           &wi);
>