On Thu, 15 Feb 2024, Ken Matsui wrote:
> This patch implements built-in trait for std::rank.
>
> gcc/cp/ChangeLog:
>
> * cp-trait.def: Define __rank.
> * semantics.cc (trait_expr_value): Handle CPTK_RANK.
> (finish_trait_expr): Likewise.
>
> gcc/testsuite/ChangeLog:
>
> * g++.dg/ext/has-builtin-1.C: Test existence of __rank.
> * g++.dg/ext/rank.C: New test.
>
> Signed-off-by: Ken Matsui <kmat...@gcc.gnu.org>
> ---
> gcc/cp/cp-trait.def | 1 +
> gcc/cp/semantics.cc | 18 ++++++++++++++++--
> gcc/testsuite/g++.dg/ext/has-builtin-1.C | 3 +++
> gcc/testsuite/g++.dg/ext/rank.C | 14 ++++++++++++++
> 4 files changed, 34 insertions(+), 2 deletions(-)
> create mode 100644 gcc/testsuite/g++.dg/ext/rank.C
>
> diff --git a/gcc/cp/cp-trait.def b/gcc/cp/cp-trait.def
> index 11270f3ae6b..3d5a7970563 100644
> --- a/gcc/cp/cp-trait.def
> +++ b/gcc/cp/cp-trait.def
> @@ -95,6 +95,7 @@ DEFTRAIT_EXPR (IS_TRIVIALLY_ASSIGNABLE,
> "__is_trivially_assignable", 2)
> DEFTRAIT_EXPR (IS_TRIVIALLY_CONSTRUCTIBLE, "__is_trivially_constructible",
> -1)
> DEFTRAIT_EXPR (IS_TRIVIALLY_COPYABLE, "__is_trivially_copyable", 1)
> DEFTRAIT_EXPR (IS_UNION, "__is_union", 1)
> +DEFTRAIT_EXPR (RANK, "__rank", 1)
> DEFTRAIT_EXPR (REF_CONSTRUCTS_FROM_TEMPORARY,
> "__reference_constructs_from_temporary", 2)
> DEFTRAIT_EXPR (REF_CONVERTS_FROM_TEMPORARY,
> "__reference_converts_from_temporary", 2)
> DEFTRAIT_TYPE (REMOVE_ALL_EXTENTS, "__remove_all_extents", 1)
> diff --git a/gcc/cp/semantics.cc b/gcc/cp/semantics.cc
> index 256e7ef8166..4f285909b83 100644
> --- a/gcc/cp/semantics.cc
> +++ b/gcc/cp/semantics.cc
> @@ -12538,6 +12538,9 @@ trait_expr_value (cp_trait_kind kind, tree type1,
> tree type2)
> case CPTK_IS_DEDUCIBLE:
> return type_targs_deducible_from (type1, type2);
>
> + /* __rank is handled in finish_trait_expr. */
> + case CPTK_RANK:
> +
> #define DEFTRAIT_TYPE(CODE, NAME, ARITY) \
> case CPTK_##CODE:
> #include "cp-trait.def"
> @@ -12698,6 +12701,7 @@ finish_trait_expr (location_t loc, cp_trait_kind
> kind, tree type1, tree type2)
> case CPTK_IS_SAME:
> case CPTK_IS_SCOPED_ENUM:
> case CPTK_IS_UNION:
> + case CPTK_RANK:
> break;
>
> case CPTK_IS_LAYOUT_COMPATIBLE:
> @@ -12729,8 +12733,18 @@ finish_trait_expr (location_t loc, cp_trait_kind
> kind, tree type1, tree type2)
> gcc_unreachable ();
> }
>
> - tree val = (trait_expr_value (kind, type1, type2)
> - ? boolean_true_node : boolean_false_node);
> + tree val;
> + if (kind == CPTK_RANK)
> + {
> + size_t rank = 0;
> + for (; TREE_CODE (type1) == ARRAY_TYPE; type1 = TREE_TYPE (type1))
> + ++rank;
> + val = build_int_cst (size_type_node, rank);
So this will be the first expression-yielding trait that's not a bool.
That's no problem conceptually, but I think we hardcode their bool-ness
near the top of finish_trait_expr when returning a templated version of
the trait. We should instead give templated __rank the type size_type_node.
> + }
> + else
> + val = (trait_expr_value (kind, type1, type2)
> + ? boolean_true_node : boolean_false_node);
> +
> return maybe_wrap_with_location (val, loc);
> }
>
> diff --git a/gcc/testsuite/g++.dg/ext/has-builtin-1.C
> b/gcc/testsuite/g++.dg/ext/has-builtin-1.C
> index 5b590db1cf6..a00193c1a81 100644
> --- a/gcc/testsuite/g++.dg/ext/has-builtin-1.C
> +++ b/gcc/testsuite/g++.dg/ext/has-builtin-1.C
> @@ -167,6 +167,9 @@
> #if !__has_builtin (__is_union)
> # error "__has_builtin (__is_union) failed"
> #endif
> +#if !__has_builtin (__rank)
> +# error "__has_builtin (__rank) failed"
> +#endif
> #if !__has_builtin (__reference_constructs_from_temporary)
> # error "__has_builtin (__reference_constructs_from_temporary) failed"
> #endif
> diff --git a/gcc/testsuite/g++.dg/ext/rank.C b/gcc/testsuite/g++.dg/ext/rank.C
> new file mode 100644
> index 00000000000..bab062d776e
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/ext/rank.C
> @@ -0,0 +1,14 @@
> +// { dg-do compile { target c++11 } }
> +
> +#define SA(X) static_assert((X),#X)
> +
> +class ClassType { };
> +
> +SA(__rank(int) == 0);
> +SA(__rank(int[2]) == 1);
> +SA(__rank(int[][4]) == 2);
> +SA(__rank(int[2][2][4][4][6][6]) == 6);
> +SA(__rank(ClassType) == 0);
> +SA(__rank(ClassType[2]) == 1);
> +SA(__rank(ClassType[][4]) == 2);
> +SA(__rank(ClassType[2][2][4][4][6][6]) == 6);
We should have a test that the __rank inside a template has the correct
type, something like (this should currently fail with your patch as-is
due to the hardcoded bool type):
template<class T> void f(T) = delete;
void f(bool);
template<class T>
void g() { f(__rank(T)); }
template void g<int>();
> --
> 2.43.0
>
>
