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?
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
