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Re: Expand oacc kernels after pass_fre
- From: Richard Biener <rguenther at suse dot de>
- To: Tom de Vries <Tom_deVries at mentor dot com>
- Cc: Thomas Schwinge <thomas at codesourcery dot com>, GCC Patches <gcc-patches at gcc dot gnu dot org>, Jakub Jelinek <jakub at redhat dot com>
- Date: Mon, 8 Jun 2015 09:25:05 +0200 (CEST)
- Subject: Re: Expand oacc kernels after pass_fre
- Authentication-results: sourceware.org; auth=none
- References: <546743BC dot 5070804 at mentor dot com> <54678B3D dot 8020009 at mentor dot com> <54730EE7 dot 40000 at mentor dot com> <5474665A dot 4070101 at mentor dot com> <87iocp1d8o dot fsf at kepler dot schwinge dot homeip dot net> <alpine dot LSU dot 2 dot 11 dot 1504220932150 dot 20496 at zhemvz dot fhfr dot qr> <557076A5 dot 7050207 at mentor dot com>
On Thu, 4 Jun 2015, Tom de Vries wrote:
> > > {
> > > gsi_next (&gsi);
> > > continue;
> > > diff --git gcc/tree-ssa-sccvn.c gcc/tree-ssa-sccvn.c
> > > index e417a15..449a615 100644
> > > --- gcc/tree-ssa-sccvn.c
> > > +++ gcc/tree-ssa-sccvn.c
> > > @@ -85,6 +85,7 @@ along with GCC; see the file COPYING3. If not see
> > > #include "ipa-ref.h"
> > > #include "plugin-api.h"
> > > #include "cgraph.h"
> > > +#include "omp-low.h"
> > >
> > > /* This algorithm is based on the SCC algorithm presented by Keith
> > > Cooper and L. Taylor Simpson in "SCC-Based Value numbering"
> > > @@ -3542,7 +3543,8 @@ visit_use (tree use)
> > > {
> > > if (gimple_code (stmt) == GIMPLE_PHI)
> > > changed = visit_phi (stmt);
> > > - else if (gimple_has_volatile_ops (stmt))
> > > + else if (gimple_has_volatile_ops (stmt)
> > > + || gimple_stmt_omp_data_i_init_p (stmt))
> >
> > No.
> >
> > What is the intent of these changes?
> >
>
> These are changes to handle the kernels region conservatively, in order to not
> undo the omp-lowering before getting to the oacc-parloops pass.
Still it feels too much like the MPX mistake (maintainance cost and
compile-time cost). How can any pass "undo" omp-lowering?
Richard.