Re: [RFC][IPA-VRP] Early VRP Implementation

[kugan <kugan dot vivekanandarajah at linaro dot org>]

Hi Andrew,

> Why separate out early VRP from tree-vrp?  Just a little curious.

It is based on the discussion in 
https://gcc.gnu.org/ml/gcc/2016-01/msg00069.html.
In summary, conclusion (based on my understanding) was to implement a 
simplified VRP algorithm that doesn't require ASSERT_EXPR insertion.


> Also it seems like if you are going to do that, putting the following
> functions in a class would be better:
> +extern void vrp_initialize (void);
> +extern void vrp_finalize (bool update, bool warn_array_bounds_p);
> +extern void vrp_intersect_ranges (value_range *vr0, value_range *vr1);
> +extern void vrp_meet (value_range *vr0, value_range *vr1);
> +extern enum ssa_prop_result vrp_visit_stmt (gimple *stmt,
> +    edge *taken_edge_p,
> +    tree *output_p);
> +extern enum ssa_prop_result vrp_visit_phi_node (gphi *phi);
> +extern bool stmt_interesting_for_vrp (gimple *stmt);
> +
> +extern void extract_range_from_assert (value_range *vr_p, tree expr);
> +extern bool update_value_range (const_tree var, value_range *vr);
> +extern value_range *get_value_range (const_tree var);
> +extern void set_value_range (value_range *vr, enum value_range_type t,
> +     tree min, tree max, bitmap equiv);
> +extern void change_value_range (const_tree var, value_range *new_vr);
> +
> +extern void dump_value_range (FILE *, value_range *);
>
> That is vrp_initialize becomes the constructor and vrp_finalize
> becomes the deconstructor.
> With both jump_thread and warn_array_bounds_p being variables you set
> while running your pass.

I will give this a try.

Thanks,
Kugan