On Thu, Sep 14, 2023 at 11:28 PM Richard Biener via Gcc-patches
<gcc-patches@gcc.gnu.org> wrote:
>
> On Fri, Sep 15, 2023 at 3:09 AM Andrew Pinski via Gcc-patches
> <gcc-patches@gcc.gnu.org> wrote:
> >
> > I noticed we sometimes lose range information in forwprop due to a few
> > match and simplify patterns optimizing away casts. So the easier way
> > to these cases is to add a match for zero_one_valued_p wich mathes
> > a cast from another zero_one_valued_p.
> > This also adds the case of `x & zero_one_valued_p` as being
> > zero_one_valued_p
> > which allows catching more cases too.
> >
> > OK? Bootstrapped and tested on x86_64-linux-gnu with no regressions.
>
> OK.
>
> I wonder if it would make a difference if we'd enable ranger unconditionally
> in forwprop (maybe with -O2+), currently it gets enabled sometimes only.
I was thinking about that though currently zero_one_valued_p only uses
the global ranger info via tree_nonzero_bits but I have patches to use
the local one too.
Thanks,
Andrew
>
> Richard.
>
> > gcc/ChangeLog:
> >
> > * match.pd (zero_one_valued_p): Match a cast from a
> > zero_one_valued_p.
> > Also match `a & zero_one_valued_p` too.
> >
> > gcc/testsuite/ChangeLog:
> >
> > * gcc.dg/tree-ssa/bool-13.c: Update testcase as we now do
> > the MIN/MAX during forwprop1.
> > ---
> > gcc/match.pd | 10 ++++++++++
> > gcc/testsuite/gcc.dg/tree-ssa/bool-13.c | 15 +++++----------
> > 2 files changed, 15 insertions(+), 10 deletions(-)
> >
> > diff --git a/gcc/match.pd b/gcc/match.pd
> > index 97db0eb5f25..39c9c81966a 100644
> > --- a/gcc/match.pd
> > +++ b/gcc/match.pd
> > @@ -2181,6 +2181,16 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
> > && (TYPE_UNSIGNED (type)
> > || TYPE_PRECISION (type) > 1))))
> >
> > +/* (a&1) is always [0,1] too. This is useful again when
> > + the range is not known. */
> > +(match zero_one_valued_p
> > + (bit_and:c@0 @1 zero_one_valued_p))
> > +
> > +/* A conversion from an zero_one_valued_p is still a [0,1].
> > + This is useful when the range of a variable is not known */
> > +(match zero_one_valued_p
> > + (convert@0 zero_one_valued_p))
> > +
> > /* Transform { 0 or 1 } * { 0 or 1 } into { 0 or 1 } & { 0 or 1 }. */
> > (simplify
> > (mult zero_one_valued_p@0 zero_one_valued_p@1)
> > diff --git a/gcc/testsuite/gcc.dg/tree-ssa/bool-13.c
> > b/gcc/testsuite/gcc.dg/tree-ssa/bool-13.c
> > index 438f15a484a..de8c99a7727 100644
> > --- a/gcc/testsuite/gcc.dg/tree-ssa/bool-13.c
> > +++ b/gcc/testsuite/gcc.dg/tree-ssa/bool-13.c
> > @@ -1,5 +1,5 @@
> > /* { dg-do compile } */
> > -/* { dg-options "-O1 -fdump-tree-optimized -fdump-tree-original
> > -fdump-tree-phiopt1 -fdump-tree-forwprop2" } */
> > +/* { dg-options "-O1 -fdump-tree-optimized -fdump-tree-original
> > -fdump-tree-forwprop1 -fdump-tree-forwprop2" } */
> > #define bool _Bool
> > int maxbool(bool ab, bool bb)
> > {
> > @@ -22,15 +22,10 @@ int minbool(bool ab, bool bb)
> > /* { dg-final { scan-tree-dump-times "MIN_EXPR" 1 "original" } } */
> > /* { dg-final { scan-tree-dump-times "if " 0 "original" } } */
> >
> > -/* PHI-OPT1 should have kept it as min/max. */
> > -/* { dg-final { scan-tree-dump-times "MAX_EXPR" 1 "phiopt1" } } */
> > -/* { dg-final { scan-tree-dump-times "MIN_EXPR" 1 "phiopt1" } } */
> > -/* { dg-final { scan-tree-dump-times "if " 0 "phiopt1" } } */
> > -
> > -/* Forwprop2 (after ccp) will convert it into &\| */
> > -/* { dg-final { scan-tree-dump-times "MAX_EXPR" 0 "forwprop2" } } */
> > -/* { dg-final { scan-tree-dump-times "MIN_EXPR" 0 "forwprop2" } } */
> > -/* { dg-final { scan-tree-dump-times "if " 0 "forwprop2" } } */
> > +/* Forwprop1 will convert it into &\| as we can detect that the arguments
> > are one_zero. */
> > +/* { dg-final { scan-tree-dump-times "MAX_EXPR" 0 "forwprop1" } } */
> > +/* { dg-final { scan-tree-dump-times "MIN_EXPR" 0 "forwprop1" } } */
> > +/* { dg-final { scan-tree-dump-times "if " 0 "forwprop1" } } */
> >
> > /* By optimize there should be no min/max nor if */
> > /* { dg-final { scan-tree-dump-times "MAX_EXPR" 0 "optimized" } } */
> > --
> > 2.31.1
> >
