[PATCH 0/2] Optimize is_scoped_enum trait performance

[PATCH 0/2] Optimize is_scoped_enum trait performance

[Ken Matsui]

This patch series optimizes is_scoped_enum trait
performance. The first patch implements __is_scoped_enum
built-in trait. The second patch optimizes is_scoped_enum
trait performance by using __is_scoped_enum built-in trait
if available.

The performance improvement is shown in the following benchmark:

https://github.com/ken-matsui/gsoc23/blob/main/is_scoped_enum_v.md#mon-sep-11-050411-pm-pdt-2023

Time: -32.717% +/- 1.67315%
Peak Memory Usage: -17.3805% +/- 0.00931763%
Total Memory Usage: -19.0881% +/- 0%

Ken Matsui (2):
  c++: Implement __is_scoped_enum built-in trait
  libstdc++: Optimize is_scoped_enum trait performance

 gcc/cp/constraint.cc                      |  3 +
 gcc/cp/cp-trait.def                       |  1 +
 gcc/cp/semantics.cc                       |  4 ++
 gcc/testsuite/g++.dg/ext/has-builtin-1.C  |  3 +
 gcc/testsuite/g++.dg/ext/is_scoped_enum.C | 67 +++++++++++++++++++++++
 libstdc++-v3/include/std/type_traits      | 12 ++++
 6 files changed, 90 insertions(+)
 create mode 100644 gcc/testsuite/g++.dg/ext/is_scoped_enum.C

-- 
2.42.0

[PATCH 1/2] c++: Implement __is_scoped_enum built-in trait

[Ken Matsui]

This patch implements built-in trait for
std::is_scoped_enum.

gcc/cp/ChangeLog:

	* cp-trait.def (IS_SCOPED_ENUM): Define
	__is_scoped_enum.
	* constraint.cc (diagnose_trait_expr): Handle
	CPTK_IS_SCOPED_ENUM.
	* semantics.cc (trait_expr_value): Likewise.
	(finish_trait_expr): Likewise.

gcc/testsuite/ChangeLog:

	* g++.dg/ext/has-builtin-1.C: Test existence of
	is_scoped_enum.
	* g++.dg/ext/is_scoped_enum.C: New test.

Signed-off-by: Ken Matsui <kmatsui@gcc.gnu.org>
---
 gcc/cp/constraint.cc                      |  3 +
 gcc/cp/cp-trait.def                       |  1 +
 gcc/cp/semantics.cc                       |  4 ++
 gcc/testsuite/g++.dg/ext/has-builtin-1.C  |  3 +
 gcc/testsuite/g++.dg/ext/is_scoped_enum.C | 67 +++++++++++++++++++++++
 5 files changed, 78 insertions(+)
 create mode 100644 gcc/testsuite/g++.dg/ext/is_scoped_enum.C

diff --git a/gcc/cp/constraint.cc b/gcc/cp/constraint.cc
index c9e4e7043cd..ba387cb5eb5 100644
--- a/gcc/cp/constraint.cc
+++ b/gcc/cp/constraint.cc
@@ -3760,6 +3760,9 @@ diagnose_trait_expr (tree expr, tree args)
     case CPTK_IS_ASSIGNABLE:
       inform (loc, "  %qT is not assignable from %qT", t1, t2);
       break;
+    case CPTK_IS_SCOPED_ENUM:
+      inform (loc, "  %qT is not a scoped enum", t1);
+      break;
     case CPTK_IS_TRIVIALLY_ASSIGNABLE:
       inform (loc, "  %qT is not trivially assignable from %qT", t1, t2);
       break;
diff --git a/gcc/cp/cp-trait.def b/gcc/cp/cp-trait.def
index 8b7fece0cc8..8caabe4c289 100644
--- a/gcc/cp/cp-trait.def
+++ b/gcc/cp/cp-trait.def
@@ -76,6 +76,7 @@ DEFTRAIT_EXPR (IS_POINTER_INTERCONVERTIBLE_BASE_OF, "__is_pointer_interconvertib
 DEFTRAIT_EXPR (IS_POD, "__is_pod", 1)
 DEFTRAIT_EXPR (IS_POLYMORPHIC, "__is_polymorphic", 1)
 DEFTRAIT_EXPR (IS_SAME, "__is_same", 2)
+DEFTRAIT_EXPR (IS_SCOPED_ENUM, "__is_scoped_enum", 1)
 DEFTRAIT_EXPR (IS_STD_LAYOUT, "__is_standard_layout", 1)
 DEFTRAIT_EXPR (IS_TRIVIAL, "__is_trivial", 1)
 DEFTRAIT_EXPR (IS_TRIVIALLY_ASSIGNABLE, "__is_trivially_assignable", 2)
diff --git a/gcc/cp/semantics.cc b/gcc/cp/semantics.cc
index 0f7f4e87ae4..7e10d81fa34 100644
--- a/gcc/cp/semantics.cc
+++ b/gcc/cp/semantics.cc
@@ -12163,6 +12163,9 @@ trait_expr_value (cp_trait_kind kind, tree type1, tree type2)
     case CPTK_IS_SAME:
       return same_type_p (type1, type2);
 
+    case CPTK_IS_SCOPED_ENUM:
+      return SCOPED_ENUM_P (type1);
+
     case CPTK_IS_STD_LAYOUT:
       return std_layout_type_p (type1);
 
@@ -12359,6 +12362,7 @@ finish_trait_expr (location_t loc, cp_trait_kind kind, tree type1, tree type2)
     case CPTK_IS_ENUM:
     case CPTK_IS_UNION:
     case CPTK_IS_SAME:
+    case CPTK_IS_SCOPED_ENUM:
       break;
 
     case CPTK_IS_LAYOUT_COMPATIBLE:
diff --git a/gcc/testsuite/g++.dg/ext/has-builtin-1.C b/gcc/testsuite/g++.dg/ext/has-builtin-1.C
index f343e153e56..bc79e50054a 100644
--- a/gcc/testsuite/g++.dg/ext/has-builtin-1.C
+++ b/gcc/testsuite/g++.dg/ext/has-builtin-1.C
@@ -146,3 +146,6 @@
 #if !__has_builtin (__remove_cvref)
 # error "__has_builtin (__remove_cvref) failed"
 #endif
+#if !__has_builtin (__is_scoped_enum)
+# error "__has_builtin (__is_scoped_enum) failed"
+#endif
diff --git a/gcc/testsuite/g++.dg/ext/is_scoped_enum.C b/gcc/testsuite/g++.dg/ext/is_scoped_enum.C
new file mode 100644
index 00000000000..a563b6ee67d
--- /dev/null
+++ b/gcc/testsuite/g++.dg/ext/is_scoped_enum.C
@@ -0,0 +1,67 @@
+// { dg-do compile { target c++11 } }
+
+#include <testsuite_tr1.h>
+
+using namespace __gnu_test;
+
+#define SA(X) static_assert((X),#X)
+
+#define SA_TEST_FN(TRAIT, TYPE, EXPECT)	\
+  SA(TRAIT(TYPE) == EXPECT);			\
+  SA(TRAIT(const TYPE) == EXPECT);
+
+#define SA_TEST_CATEGORY(TRAIT, TYPE, EXPECT)	\
+  SA(TRAIT(TYPE) == EXPECT);					\
+  SA(TRAIT(const TYPE) == EXPECT);				\
+  SA(TRAIT(volatile TYPE) == EXPECT);			\
+  SA(TRAIT(const volatile TYPE) == EXPECT)
+
+enum class E { e1, e2 };
+SA_TEST_CATEGORY(__is_scoped_enum, E, true);
+enum class Ec : char { e1, e2 };
+SA_TEST_CATEGORY(__is_scoped_enum, Ec, true);
+
+// negative tests
+enum U { u1, u2 };
+SA_TEST_CATEGORY(__is_scoped_enum, U, false);
+enum F : int { f1, f2 };
+SA_TEST_CATEGORY(__is_scoped_enum, F, false);
+struct S;
+SA_TEST_CATEGORY(__is_scoped_enum, S, false);
+struct S { };
+SA_TEST_CATEGORY(__is_scoped_enum, S, false);
+
+SA_TEST_CATEGORY(__is_scoped_enum, int, false);
+SA_TEST_CATEGORY(__is_scoped_enum, int[], false);
+SA_TEST_CATEGORY(__is_scoped_enum, int[2], false);
+SA_TEST_CATEGORY(__is_scoped_enum, int[][2], false);
+SA_TEST_CATEGORY(__is_scoped_enum, int[2][3], false);
+SA_TEST_CATEGORY(__is_scoped_enum, int*, false);
+SA_TEST_CATEGORY(__is_scoped_enum, int&, false);
+SA_TEST_CATEGORY(__is_scoped_enum, int*&, false);
+SA_TEST_FN(__is_scoped_enum, int(), false);
+SA_TEST_FN(__is_scoped_enum, int(*)(), false);
+SA_TEST_FN(__is_scoped_enum, int(&)(), false);
+
+enum opaque_unscoped : short;
+enum class opaque_scoped;
+enum class opaque_scoped_with_base : long;
+
+SA_TEST_CATEGORY(__is_scoped_enum, opaque_unscoped, false);
+SA_TEST_CATEGORY(__is_scoped_enum, opaque_scoped, true);
+SA_TEST_CATEGORY(__is_scoped_enum, opaque_scoped_with_base, true);
+
+enum unscoped {
+  u_is_scoped = __is_scoped_enum(unscoped),
+};
+SA( ! unscoped::u_is_scoped );
+
+enum unscoped_fixed : char {
+  uf_is_scoped = __is_scoped_enum(unscoped_fixed),
+};
+SA( ! unscoped_fixed::uf_is_scoped );
+
+enum class scoped {
+  is_scoped = __is_scoped_enum(scoped),
+};
+SA( (bool) scoped::is_scoped );
-- 
2.42.0

[PATCH 2/2] libstdc++: Optimize is_scoped_enum trait performance

[Ken Matsui]

This patch optimizes the performance of the is_scoped_enum trait
by dispatching to the new __is_scoped_enum built-in trait.

libstdc++-v3/ChangeLog:

	* include/std/type_traits (is_scoped_enum): Use
	__is_scoped_enum built-in trait.
	(is_scoped_enum_v): Likewise.

Signed-off-by: Ken Matsui <kmatsui@gcc.gnu.org>
---
 libstdc++-v3/include/std/type_traits | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/libstdc++-v3/include/std/type_traits b/libstdc++-v3/include/std/type_traits
index 677cd934b94..26ae491fa69 100644
--- a/libstdc++-v3/include/std/type_traits
+++ b/libstdc++-v3/include/std/type_traits
@@ -3585,6 +3585,12 @@ template<typename _Ret, typename _Fn, typename... _Args>
   /// True if the type is a scoped enumeration type.
   /// @since C++23
 
+# if _GLIBCXX_USE_BUILTIN_TRAIT(__is_scoped_enum)
+  template<typename _Tp>
+    struct is_scoped_enum
+    : bool_constant<__is_scoped_enum(_Tp)>
+    { };
+# else
   template<typename _Tp>
     struct is_scoped_enum
     : false_type
@@ -3596,11 +3602,17 @@ template<typename _Ret, typename _Fn, typename... _Args>
     struct is_scoped_enum<_Tp>
     : bool_constant<!requires(_Tp __t, void(*__f)(int)) { __f(__t); }>
     { };
+# endif
 
   /// @ingroup variable_templates
   /// @since C++23
+# if _GLIBCXX_USE_BUILTIN_TRAIT(__is_scoped_enum)
+  template<typename _Tp>
+    inline constexpr bool is_scoped_enum_v = __is_scoped_enum(_Tp);
+# else
   template<typename _Tp>
     inline constexpr bool is_scoped_enum_v = is_scoped_enum<_Tp>::value;
+# endif
 #endif
 
 #ifdef __cpp_lib_reference_from_temporary // C++ >= 23 && ref_{converts,constructs}_from_temp
-- 
2.42.0

Re: [PATCH 2/2] libstdc++: Optimize is_scoped_enum trait performance

[Jonathan Wakely]

[-- Attachment #1: Type: text/plain, Size: 1931 bytes --]

On Tue, 12 Sept 2023, 01:21 Ken Matsui via Libstdc++, <libstdc++@gcc.gnu.org>
wrote:

> This patch optimizes the performance of the is_scoped_enum trait
> by dispatching to the new __is_scoped_enum built-in trait.
>

OK for trunk (after the built-in is in the front end), thanks.



> libstdc++-v3/ChangeLog:
>
>         * include/std/type_traits (is_scoped_enum): Use
>         __is_scoped_enum built-in trait.
>         (is_scoped_enum_v): Likewise.
>
> Signed-off-by: Ken Matsui <kmatsui@gcc.gnu.org>
> ---
>  libstdc++-v3/include/std/type_traits | 12 ++++++++++++
>  1 file changed, 12 insertions(+)
>
> diff --git a/libstdc++-v3/include/std/type_traits
> b/libstdc++-v3/include/std/type_traits
> index 677cd934b94..26ae491fa69 100644
> --- a/libstdc++-v3/include/std/type_traits
> +++ b/libstdc++-v3/include/std/type_traits
> @@ -3585,6 +3585,12 @@ template<typename _Ret, typename _Fn, typename...
> _Args>
>    /// True if the type is a scoped enumeration type.
>    /// @since C++23
>
> +# if _GLIBCXX_USE_BUILTIN_TRAIT(__is_scoped_enum)
> +  template<typename _Tp>
> +    struct is_scoped_enum
> +    : bool_constant<__is_scoped_enum(_Tp)>
> +    { };
> +# else
>    template<typename _Tp>
>      struct is_scoped_enum
>      : false_type
> @@ -3596,11 +3602,17 @@ template<typename _Ret, typename _Fn, typename...
> _Args>
>      struct is_scoped_enum<_Tp>
>      : bool_constant<!requires(_Tp __t, void(*__f)(int)) { __f(__t); }>
>      { };
> +# endif
>
>    /// @ingroup variable_templates
>    /// @since C++23
> +# if _GLIBCXX_USE_BUILTIN_TRAIT(__is_scoped_enum)
> +  template<typename _Tp>
> +    inline constexpr bool is_scoped_enum_v = __is_scoped_enum(_Tp);
> +# else
>    template<typename _Tp>
>      inline constexpr bool is_scoped_enum_v = is_scoped_enum<_Tp>::value;
> +# endif
>  #endif
>
>  #ifdef __cpp_lib_reference_from_temporary // C++ >= 23 &&
> ref_{converts,constructs}_from_temp
> --
> 2.42.0
>
>