On Fri, 2 Jul 2021, Richard Biener wrote:
> On Thu, 1 Jul 2021, Michael Matz wrote:
>
> > Hello,
> >
> > On Thu, 1 Jul 2021, Richard Biener wrote:
> >
> > > diff --git a/gcc/gimple-loop-interchange.cc
> > > b/gcc/gimple-loop-interchange.cc
> > > index 43045c5455e..43ef112a2d0 100644
> > > --- a/gcc/gimple-loop-interchange.cc
> > > +++ b/gcc/gimple-loop-interchange.cc
> > > @@ -1043,8 +1043,11 @@ tree_loop_interchange::valid_data_dependences
> > > (unsigned i_idx, unsigned o_idx,
> > > continue;
> > >
> > > /* Be conservative, skip case if either direction at i_idx/o_idx
> > > - levels is not '=' (for the inner loop) or '<'. */
> > > - if (dist_vect[i_idx] < 0 || dist_vect[o_idx] <= 0)
> > > + levels is not '=' or '<'. */
> > > + if (dist_vect[i_idx] < 0
> > > + || (DDR_REVERSED_P (ddr) && dist_vect[i_idx] > 0)
> > > + || dist_vect[o_idx] < 0
> > > + || (DDR_REVERSED_P (ddr) && dist_vect[o_idx] > 0))
> >
> > Hmm, if DDR_REVERSED_P matters here, then it should matter for all arms.
> > IOW: < 0 should be tested only when !DDR_REVERSED_P, not always:
> >
> > if ((!DDR_REVERSED_P (ddr) && dist_vect[i_idx] < 0)
> > || (DDR_REVERSED_P (ddr) && dist_vect[i_idx] > 0)
> > || (!DDR_REVERSED_P (ddr) && dist_vect[o_idx] < 0)
> > || (DDR_REVERSED_P (ddr) && dist_vect[o_idx] > 0))
> >
> > (what you have effectively written is a condition that allows only 0 when
> > DDR_REVERSED_P)
>
> True - been fixing bugs too fast I guess. Maybe the 3rd time's the charm
> then ;)
Bootstrapped and tested on x86_64-unknown-linux-gnu, pushed.
Richard.
>From 094af28137de5c55a21123c3b4e06e7d7a08bb5a Mon Sep 17 00:00:00 2001
From: Richard Biener <rguent...@suse.de>
Date: Fri, 2 Jul 2021 08:51:43 +0200
Subject: [PATCH] tree-optimization/101280 - re-revise interchange fix for
PR101173
To: gcc-patches@gcc.gnu.org
The following fixes up the revision of the original fix for PR101173
to properly guard all dependence checks with DDR_REVERSED_P or its
inverse.
2021-07-01 Richard Biener <rguent...@suse.de>
PR tree-optimization/101280
PR tree-optimization/101173
* gimple-loop-interchange.cc
(tree_loop_interchange::valid_data_dependences): Properly
guard all dependence checks with DDR_REVERSED_P or its
inverse.
---
gcc/gimple-loop-interchange.cc | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/gcc/gimple-loop-interchange.cc b/gcc/gimple-loop-interchange.cc
index 43ef112a2d0..7a88faa2c07 100644
--- a/gcc/gimple-loop-interchange.cc
+++ b/gcc/gimple-loop-interchange.cc
@@ -1044,9 +1044,9 @@ tree_loop_interchange::valid_data_dependences (unsigned
i_idx, unsigned o_idx,
/* Be conservative, skip case if either direction at i_idx/o_idx
levels is not '=' or '<'. */
- if (dist_vect[i_idx] < 0
+ if ((!DDR_REVERSED_P (ddr) && dist_vect[i_idx] < 0)
|| (DDR_REVERSED_P (ddr) && dist_vect[i_idx] > 0)
- || dist_vect[o_idx] < 0
+ || (!DDR_REVERSED_P (ddr) && dist_vect[o_idx] < 0)
|| (DDR_REVERSED_P (ddr) && dist_vect[o_idx] > 0))
return false;
}
--
2.26.2
