Re: [PATCH] i386: fix assert (__builtin_cpu_supports ("x86-64") >= 0)

[Uros Bizjak <ubizjak@gmail.com>]

On Fri, Dec 2, 2022 at 10:46 AM Martin Liška <mliska@suse.cz> wrote:
>
> PING^1
>
> On 11/25/22 13:57, Martin Liška wrote:
> > Similar story as PR103661, we again return a negative number
> > for __builtin_cpu_supports:
> >
> > Documentation says:
> >
> > int __builtin_cpu_supports(const char *feature)
> > This function returns a positive integer if the run-time CPU supports feature and returns 0 otherwise.
> > while we return -2147483648.
> >
> > Moreover, I noticed "x86-64" is not a valid option for __builtin_cpu_is,
> > but for __builtin_cpu_supports.
> >
> > Patch can bootstrap on x86_64-linux-gnu and survives regression tests.
> >
> > Ready to be installed?
> > Thanks,
> > Martin
> >
> > PR target/107551
> >
> > gcc/ChangeLog:
> >
> >       * config/i386/i386-builtins.cc (fold_builtin_cpu): Use same path
> >       as for PR103661.
> >       * doc/extend.texi: Fix "x86-64" use.
> >
> > gcc/testsuite/ChangeLog:
> >
> >       * gcc.target/i386/builtin_target.c: Add more checks.

I'm not quite familiar with this part of the compiler, but if Jakub is
OK with the patch, consider it rubber-stamped OK.

Thanks,
Uros.

> > ---
> >  gcc/config/i386/i386-builtins.cc              | 25 ++++++++-----------
> >  gcc/doc/extend.texi                           | 22 ++++++++--------
> >  .../gcc.target/i386/builtin_target.c          |  5 ++++
> >  3 files changed, 26 insertions(+), 26 deletions(-)
> >
> > diff --git a/gcc/config/i386/i386-builtins.cc b/gcc/config/i386/i386-builtins.cc
> > index eacdf072244..c57c1380298 100644
> > --- a/gcc/config/i386/i386-builtins.cc
> > +++ b/gcc/config/i386/i386-builtins.cc
> > @@ -2181,18 +2181,14 @@ fold_builtin_cpu (tree fndecl, tree *args)
> >             varpool_node::add (ix86_cpu_features2_var);
> >           }
> >
> > +       /* Skip __cpu_features[0].  */
> >         feature -= INT_TYPE_SIZE;
> > -       field_val = 1U << (feature % INT_TYPE_SIZE);
> >         tree index = size_int (feature / INT_TYPE_SIZE);
> > +       feature = feature % INT_TYPE_SIZE;
> >         array_elt = build4 (ARRAY_REF, unsigned_type_node,
> >                             ix86_cpu_features2_var,
> >                             index, NULL_TREE, NULL_TREE);
> >         /* Return __cpu_features2[index] & field_val  */
> > -       final = build2 (BIT_AND_EXPR, unsigned_type_node,
> > -                       array_elt,
> > -                       build_int_cstu (unsigned_type_node,
> > -                                       field_val));
> > -       return build1 (NOP_EXPR, integer_type_node, final);
> >       }
> >        else
> >       {
> > @@ -2209,16 +2205,17 @@ fold_builtin_cpu (tree fndecl, tree *args)
> >         array_elt = build4 (ARRAY_REF, unsigned_type_node, ref,
> >                             integer_zero_node, NULL_TREE, NULL_TREE);
> >
> > -       field_val = (1U << feature);
> >         /* Return __cpu_model.__cpu_features[0] & field_val  */
> > -       final = build2 (BIT_AND_EXPR, unsigned_type_node, array_elt,
> > -                       build_int_cstu (unsigned_type_node, field_val));
> > -       if (feature == (INT_TYPE_SIZE - 1))
> > -         return build2 (NE_EXPR, integer_type_node, final,
> > -                        build_int_cst (unsigned_type_node, 0));
> > -       else
> > -         return build1 (NOP_EXPR, integer_type_node, final);
> >       }
> > +
> > +      field_val = (1U << feature);
> > +      final = build2 (BIT_AND_EXPR, unsigned_type_node, array_elt,
> > +                   build_int_cstu (unsigned_type_node, field_val));
> > +      if (feature == (INT_TYPE_SIZE - 1))
> > +     return build2 (NE_EXPR, integer_type_node, final,
> > +                    build_int_cst (unsigned_type_node, 0));
> > +      else
> > +     return build1 (NOP_EXPR, integer_type_node, final);
> >      }
> >    gcc_unreachable ();
> >  }
> > diff --git a/gcc/doc/extend.texi b/gcc/doc/extend.texi
> > index b1dd39e64b8..d3812fa55b0 100644
> > --- a/gcc/doc/extend.texi
> > +++ b/gcc/doc/extend.texi
> > @@ -21897,18 +21897,6 @@ AMD Family 19h Zen version 3.
> >
> >  @item znver4
> >  AMD Family 19h Zen version 4.
> > -
> > -@item x86-64
> > -Baseline x86-64 microarchitecture level (as defined in x86-64 psABI).
> > -
> > -@item x86-64-v2
> > -x86-64-v2 microarchitecture level.
> > -
> > -@item x86-64-v3
> > -x86-64-v3 microarchitecture level.
> > -
> > -@item x86-64-v4
> > -x86-64-v4 microarchitecture level.
> >  @end table
> >
> >  Here is an example:
> > @@ -22002,6 +21990,16 @@ VPCLMULQDQ instructions.
> >  AVX512VNNI instructions.
> >  @item avx512bitalg
> >  AVX512BITALG instructions.
> > +@item x86-64
> > +Baseline x86-64 microarchitecture level (as defined in x86-64 psABI).
> > +@item x86-64-v2
> > +x86-64-v2 microarchitecture level.
> > +@item x86-64-v3
> > +x86-64-v3 microarchitecture level.
> > +@item x86-64-v4
> > +x86-64-v4 microarchitecture level.
> > +
> > +
> >  @end table
> >
> >  Here is an example:
> > diff --git a/gcc/testsuite/gcc.target/i386/builtin_target.c b/gcc/testsuite/gcc.target/i386/builtin_target.c
> > index 3e7505a8c3a..fff643c13b0 100644
> > --- a/gcc/testsuite/gcc.target/i386/builtin_target.c
> > +++ b/gcc/testsuite/gcc.target/i386/builtin_target.c
> > @@ -95,6 +95,11 @@ quick_check ()
> >
> >    assert (__builtin_cpu_supports ("avx512vpopcntdq") >= 0);
> >
> > +  assert (__builtin_cpu_supports ("x86-64") >= 0);
> > +  assert (__builtin_cpu_supports ("x86-64-v2") >= 0);
> > +  assert (__builtin_cpu_supports ("x86-64-v3") >= 0);
> > +  assert (__builtin_cpu_supports ("x86-64-v4") >= 0);
> > +
> >    /* Check CPU type.  */
> >    assert (__builtin_cpu_is ("amd") >= 0);
> >
>