Re: [Patch] PR tree-optimization/68234 Improve range info for loop Phi node

[Richard Biener <rguenther@suse.de>]

On Wed, 11 Nov 2015, Jiong Wang wrote:

> As discussed at https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68234, this
> patch haven't touch the existed code logic in vrp_visit_phi_node, it
> only entends SCEV check to those VR_VARYING loop PHI node.
> 
> Previously, we only do this check if the PHI node is with valid range
> info but later dropped either side to infinite. The miss of those PHI
> node with initial estimiation of VR_VARYING caused the missing of some
> further optimization opportunity, for example the testcase included in
> this patch, with improved range info, we can efficient turn the signed
> divide into right shift.
> 
> This patch pass x86-64 and AArch64 boostrap, no regression on both.
> Meanwhile a simple benchmaring shows there are quite a few new VR_RANGE
> found after this patch during gcc bootstrapping. There is no performance
> regression on spec2006 int on aarch64.
> 
> During gcc bootstrapping, on x86-64 there are 4828 new VR_VARYING -> VR_RANGE
> found by vrp1, and 5008 new by vrp2.
> 
> While on AArch64 there are 44756 new by vrp1, and 6047 new by vrp2.
> 
> OK for trunk?

Ok.

Thanks,
Richard.

> 2015-11-11  Richard Biener  <rguenth@gcc.gnu.org>
>             Jiong Wang      <jiong.wang@arm.com>
> gcc/
>   PR tree-optimization/68234
>   * tree-vrp.c (vrp_visit_phi_node): Extend SCEV check to those loop PHI
>   node which estimiated to be VR_VARYING initially.
> 
> gcc/testsuite/
>   * gcc.dg/tree-ssa/pr68234.c: New testcase.