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Re: [range-ops] patch 05/04: bonus round!


On 7/1/19 4:24 AM, Aldy Hernandez wrote:
> This is completely unrelated to range-ops itself, but may yield better
> results in value_range intersections.  It's just something I found while
> working on VRP, and have been dragging around on our branch.
> 
> If we know the intersection of two ranges is the empty set, there is no
> need to conservatively add anything to the result.
> 
> Tested on x86-64 Linux with --enable-languages=all.
> 
> Aldy
> 
> range-ops-intersect-undefined.patch
> 
> commit 4f9aa7bd1066267eee92f622ff29d78534158e20
> Author: Aldy Hernandez <aldyh@redhat.com>
> Date:   Fri Jun 28 11:34:19 2019 +0200
> 
>     Do not try to further refine a VR_UNDEFINED result when intersecting
>     value_ranges.
> 
> diff --git a/gcc/ChangeLog b/gcc/ChangeLog
> index 01fb97cedb2..b0d78ee6871 100644
> --- a/gcc/ChangeLog
> +++ b/gcc/ChangeLog
> @@ -1,3 +1,9 @@
> +2019-07-01  Aldy Hernandez  <aldyh@redhat.com>
> +
> +	* tree-vrp.c (intersect_ranges): If we know the intersection is
> +	empty, there is no need to conservatively add anything else to
> +	the set.
Do we have a test where this improves the code or at least the computed
ranges?

jeff


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