Re: [PATCH 2/2] MATCH: Add `a == b | a cmp b` and `a != b & a cmp b` simplifications

[Andrew Pinski <pinskia@gmail.com>]

On Mon, Jul 31, 2023 at 3:53 AM Richard Biener via Gcc-patches
<gcc-patches@gcc.gnu.org> wrote:
>
> On Mon, Jul 31, 2023 at 7:35 AM Andrew Pinski via Gcc-patches
> <gcc-patches@gcc.gnu.org> wrote:
> >
> > Even though these are done by combine_comparisons, we can add them to match
> > to allow simplifcations during match rather than just during reassoc/ifcombine.
> >
> > OK? Bootstrapped and tested on x86_64-linux-gnu with no regressions.
>
> OK.  Note we want to get rid of the GENERIC folding parts of
> maybe_fold_{and,or}_comparisons which is what those passes rely on.

Yes that was the idea here but there are still a few more cases that
need to be handled: Floating point, and some integer constants due to
`a <= 1` changing to `a < 0`.

Thanks,
Andrew

>
> Richard.
>
> > gcc/ChangeLog:
> >
> >         PR tree-optimization/106164
> >         * match.pd (`a != b & a <= b`, `a != b & a >= b`,
> >         `a == b | a < b`, `a == b | a > b`): Handle these cases
> >         too.
> >
> > gcc/testsuite/ChangeLog:
> >
> >         PR tree-optimization/106164
> >         * gcc.dg/tree-ssa/cmpbit-2.c: New test.
> > ---
> >  gcc/match.pd                             | 32 +++++++++++++++++--
> >  gcc/testsuite/gcc.dg/tree-ssa/cmpbit-2.c | 39 ++++++++++++++++++++++++
> >  2 files changed, 69 insertions(+), 2 deletions(-)
> >  create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/cmpbit-2.c
> >
> > diff --git a/gcc/match.pd b/gcc/match.pd
> > index 00af5d99119..cf8057701ea 100644
> > --- a/gcc/match.pd
> > +++ b/gcc/match.pd
> > @@ -2832,7 +2832,21 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
> >       (switch
> >        (if (code1 == EQ_EXPR && val) @3)
> >        (if (code1 == EQ_EXPR && !val) { constant_boolean_node (false, type); })
> > -      (if (code1 == NE_EXPR && !val) @4)))))))
> > +      (if (code1 == NE_EXPR && !val) @4)
> > +      (if (code1 == NE_EXPR
> > +           && code2 == GE_EXPR
> > +          && cmp == 0)
> > +       (gt @0 @1))
> > +      (if (code1 == NE_EXPR
> > +           && code2 == LE_EXPR
> > +          && cmp == 0)
> > +       (lt @0 @1))
> > +     )
> > +    )
> > +   )
> > +  )
> > + )
> > +)
> >
> >  /* Convert (X OP1 CST1) && (X OP2 CST2).
> >     Convert (X OP1 Y) && (X OP2 Y).  */
> > @@ -2917,7 +2931,21 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
> >       (switch
> >        (if (code1 == EQ_EXPR && val) @4)
> >        (if (code1 == NE_EXPR && val) { constant_boolean_node (true, type); })
> > -      (if (code1 == NE_EXPR && !val) @3)))))))
> > +      (if (code1 == NE_EXPR && !val) @3)
> > +      (if (code1 == EQ_EXPR
> > +           && code2 == GT_EXPR
> > +          && cmp == 0)
> > +       (ge @0 @1))
> > +      (if (code1 == EQ_EXPR
> > +           && code2 == LT_EXPR
> > +          && cmp == 0)
> > +       (le @0 @1))
> > +     )
> > +    )
> > +   )
> > +  )
> > + )
> > +)
> >
> >  /* Convert (X OP1 CST1) || (X OP2 CST2).
> >     Convert (X OP1 Y)    || (X OP2 Y).  */
> > diff --git a/gcc/testsuite/gcc.dg/tree-ssa/cmpbit-2.c b/gcc/testsuite/gcc.dg/tree-ssa/cmpbit-2.c
> > new file mode 100644
> > index 00000000000..c4226ef01af
> > --- /dev/null
> > +++ b/gcc/testsuite/gcc.dg/tree-ssa/cmpbit-2.c
> > @@ -0,0 +1,39 @@
> > +/* { dg-do compile } */
> > +/* { dg-options "-O1 -fno-tree-reassoc -fdump-tree-optimized-raw" } */
> > +
> > +_Bool f(int a, int b)
> > +{
> > +  _Bool c = a == b;
> > +  _Bool d = a > b;
> > +  return c | d;
> > +}
> > +
> > +_Bool f1(int a, int b)
> > +{
> > +  _Bool c = a != b;
> > +  _Bool d = a >= b;
> > +  return c & d;
> > +}
> > +
> > +_Bool g(int a, int b)
> > +{
> > +  _Bool c = a == b;
> > +  _Bool d = a < b;
> > +  return c | d;
> > +}
> > +
> > +_Bool g1(int a, int b)
> > +{
> > +  _Bool c = a != b;
> > +  _Bool d = a <= b;
> > +  return c & d;
> > +}
> > +
> > +
> > +/* We should be able to optimize these without reassociation too. */
> > +/* { dg-final { scan-tree-dump-not "bit_and_expr," "optimized" } } */
> > +/* { dg-final { scan-tree-dump-not "bit_ior_expr," "optimized" } } */
> > +/* { dg-final { scan-tree-dump-times "gt_expr," 1 "optimized" } } */
> > +/* { dg-final { scan-tree-dump-times "ge_expr," 1 "optimized" } } */
> > +/* { dg-final { scan-tree-dump-times "lt_expr," 1 "optimized" } } */
> > +/* { dg-final { scan-tree-dump-times "le_expr," 1 "optimized" } } */
> > --
> > 2.31.1
> >