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Re: [Patch] PR tree-optimization/68234 Improve range info for loop Phi node
- From: Richard Biener <rguenther at suse dot de>
- To: Jiong Wang <jiong dot wang at foss dot arm dot com>
- Cc: GCC Patches <gcc-patches at gcc dot gnu dot org>
- Date: Wed, 11 Nov 2015 11:26:14 +0100 (CET)
- Subject: Re: [Patch] PR tree-optimization/68234 Improve range info for loop Phi node
- Authentication-results: sourceware.org; auth=none
- References: <5643091B dot 9090009 at foss dot arm dot com>
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.