On Fri, 17 Nov 2023, Jakub Jelinek wrote:
> On Thu, Nov 16, 2023 at 11:49:03PM +0000, Joseph Myers wrote:
> > > > While filing a clang request to return 18 on _BitInts for
> > > > __builtin_classify_type instead of -1 they return currently, I've
> > > > noticed that we return -1 for vector types. I'm not convinced it is a
> > > > good
> > > > idea to change behavior of __builtin_classify_type (vector_expression)
> > > > after 22 years it behaved one way (returned -1), but the
> > > > __builtin_classify_type (type) form is a new extension added for GCC 14,
> > > > so this patch returns 19 for vectors just in that second form. Many
> > > > other
> > > > return values are only accessible from the second form as well (mostly
> > > > because
> > > > of argument promotions), so I think it is fine like that.
> > > >
> > > > Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
> > >
> > > The C++ changes are OK (and obvious). I'm skeptical of the choice to keep
> > > returning -1 for the expression form, it seems more likely to cause
> > > problems
> > > (due to it disagreeing with the type form) than changing it (due to old
> > > code
> > > somehow relying on -1?). But people who are more familiar with the use of
> > > __builtin_classify_type should make the call.
> >
> > I'm also doubtful of keeping returning -1 for vectors in expression form
> > (I'd be surprised if people are actually using __builtin_classify_type
> > with vectors). The C changes are OK (but the front-end changes wouldn't
> > be needed at all if the vector and type argument cases aren't
> > distinguished).
>
> Given that you've both agreed that you think changing
> __builtin_classify_type (vector_expr) is ok (hopefully in the wild people
> test bct against known values rather than pretending to know what the
> unknown -1 means because it can mean multiple type kinds), here is a simpler
> patch which changes it even for that.
>
> Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
OK. Do we have to adjust any of our documentation for this?
> 2023-11-17 Jakub Jelinek <ja...@redhat.com>
>
> gcc/
> * typeclass.h (enum type_class): Add vector_type_class.
> * builtins.cc (type_to_class): Return vector_type_class for
> VECTOR_TYPE.
> gcc/testsuite/
> * c-c++-common/builtin-classify-type-1.c (main): Add tests for vector
> types.
>
> --- gcc/typeclass.h.jj 2023-09-06 17:28:24.238977355 +0200
> +++ gcc/typeclass.h 2023-11-10 10:50:59.519007647 +0100
> @@ -38,7 +38,7 @@ enum type_class
> record_type_class, union_type_class,
> array_type_class, string_type_class,
> lang_type_class, opaque_type_class,
> - bitint_type_class
> + bitint_type_class, vector_type_class
> };
>
> #endif /* GCC_TYPECLASS_H */
> --- gcc/builtins.cc.jj 2023-11-09 09:17:40.230182483 +0100
> +++ gcc/builtins.cc 2023-11-10 11:19:29.669129855 +0100
> @@ -1859,6 +1859,7 @@ type_to_class (tree type)
> case LANG_TYPE: return lang_type_class;
> case OPAQUE_TYPE: return opaque_type_class;
> case BITINT_TYPE: return bitint_type_class;
> + case VECTOR_TYPE: return vector_type_class;
> default: return no_type_class;
> }
> }
> --- gcc/testsuite/c-c++-common/builtin-classify-type-1.c.jj 2023-09-26
> 09:25:30.019599039 +0200
> +++ gcc/testsuite/c-c++-common/builtin-classify-type-1.c 2023-11-10
> 11:02:01.927776922 +0100
> @@ -22,6 +22,10 @@ main ()
> const char *p = (const char *) 0;
> float f = 0.0;
> _Complex double c = 0.0;
> + typedef int VI __attribute__((vector_size (4 * sizeof (int))));
> + typedef float VF __attribute__((vector_size (4 * sizeof (int))));
> + VI vi = { 0, 0, 0, 0 };
> + VF vf = { 0.0f, 0.0f, 0.0f, 0.0f };
> #ifdef __cplusplus
> struct T { void foo (); };
> int &r = a[0];
> @@ -43,6 +47,8 @@ main ()
> static_assert (__builtin_classify_type (struct S) == 12, "");
> static_assert (__builtin_classify_type (union U) == 13, "");
> static_assert (__builtin_classify_type (int [2]) == 14, "");
> + static_assert (__builtin_classify_type (VI) == 19, "");
> + static_assert (__builtin_classify_type (VF) == 19, "");
> static_assert (__builtin_classify_type (__typeof__ (a[0])) == 1, "");
> static_assert (__builtin_classify_type (__typeof__ (e)) == 3, "");
> static_assert (__builtin_classify_type (__typeof__ (b)) == 4, "");
> @@ -57,6 +63,8 @@ main ()
> static_assert (__builtin_classify_type (__typeof__ (s)) == 12, "");
> static_assert (__builtin_classify_type (__typeof__ (u)) == 13, "");
> static_assert (__builtin_classify_type (__typeof__ (a)) == 14, "");
> + static_assert (__builtin_classify_type (__typeof__ (vi)) == 19, "");
> + static_assert (__builtin_classify_type (__typeof__ (vf)) == 19, "");
> #ifndef __cplusplus
> static_assert (__builtin_classify_type (a[0]) == 1, "");
> static_assert (__builtin_classify_type (e) == 1, "");
> @@ -102,4 +110,8 @@ main ()
> abort ();
> if (__builtin_classify_type (a) != 5)
> abort ();
> + if (__builtin_classify_type (vi) != 19)
> + abort ();
> + if (__builtin_classify_type (vf) != 19)
> + abort ();
> }
>
>
> Jakub
>
>
--
Richard Biener <rguent...@suse.de>
SUSE Software Solutions Germany GmbH,
Frankenstrasse 146, 90461 Nuernberg, Germany;
GF: Ivo Totev, Andrew McDonald, Werner Knoblich; (HRB 36809, AG Nuernberg)
