[PATCH 0/2] Optimize is_bounded_array trait performance

[PATCH 0/2] Optimize is_bounded_array trait performance

[Ken Matsui]

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

The performance improvement is shown in the following benchmark:

https://github.com/ken-matsui/gsoc23/blob/main/is_bounded_array_v.md#mon-sep-11-072608-pm-pdt-2023

Time:
Peak Memory Usage:
Total Memory Usage:

Ken Matsui (2):
  c++: Implement __is_bounded_array built-in trait
  libstdc++: Optimize is_bounded_array 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_bounded_array.C | 38 +++++++++++++++++++++
 libstdc++-v3/include/std/type_traits        |  5 +++
 6 files changed, 54 insertions(+)
 create mode 100644 gcc/testsuite/g++.dg/ext/is_bounded_array.C

-- 
2.42.0

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

[Ken Matsui]

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

gcc/cp/ChangeLog:

	* cp-trait.def (IS_BOUNDED_ARRAY): Define __is_bounded_array.
	* constraint.cc (diagnose_trait_expr): Handle CPTK_IS_BOUNDED_ARRAY.
	* semantics.cc (trait_expr_value): Likewise.
	(finish_trait_expr): Likewise.

gcc/testsuite/ChangeLog:

	* g++.dg/ext/has-builtin-1.C: Test existence of __is_bounded_array.
	* g++.dg/ext/is_bounded_array.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_bounded_array.C | 38 +++++++++++++++++++++
 5 files changed, 49 insertions(+)
 create mode 100644 gcc/testsuite/g++.dg/ext/is_bounded_array.C

diff --git a/gcc/cp/constraint.cc b/gcc/cp/constraint.cc
index c9e4e7043cd..4db9acade65 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_BOUNDED_ARRAY:
+      inform (loc, "  %qT is not a bounded array", 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..d50ca8a7781 100644
--- a/gcc/cp/cp-trait.def
+++ b/gcc/cp/cp-trait.def
@@ -61,6 +61,7 @@ DEFTRAIT_EXPR (IS_ABSTRACT, "__is_abstract", 1)
 DEFTRAIT_EXPR (IS_AGGREGATE, "__is_aggregate", 1)
 DEFTRAIT_EXPR (IS_ASSIGNABLE, "__is_assignable", 2)
 DEFTRAIT_EXPR (IS_BASE_OF, "__is_base_of", 2)
+DEFTRAIT_EXPR (IS_BOUNDED_ARRAY, "__is_bounded_array", 1)
 DEFTRAIT_EXPR (IS_CLASS, "__is_class", 1)
 DEFTRAIT_EXPR (IS_CONSTRUCTIBLE, "__is_constructible", -1)
 DEFTRAIT_EXPR (IS_CONVERTIBLE, "__is_convertible", 2)
diff --git a/gcc/cp/semantics.cc b/gcc/cp/semantics.cc
index 0f7f4e87ae4..87eeed34068 100644
--- a/gcc/cp/semantics.cc
+++ b/gcc/cp/semantics.cc
@@ -12142,6 +12142,9 @@ trait_expr_value (cp_trait_kind kind, tree type1, tree type2)
     case CPTK_IS_ENUM:
       return type_code1 == ENUMERAL_TYPE;
 
+    case CPTK_IS_BOUNDED_ARRAY:
+      return type_code1 == ARRAY_TYPE && TYPE_DOMAIN (type1);
+
     case CPTK_IS_FINAL:
       return CLASS_TYPE_P (type1) && CLASSTYPE_FINAL (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_BOUNDED_ARRAY:
       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..04db7756a26 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_bounded_array)
+# error "__has_builtin (__is_bounded_array) failed"
+#endif
diff --git a/gcc/testsuite/g++.dg/ext/is_bounded_array.C b/gcc/testsuite/g++.dg/ext/is_bounded_array.C
new file mode 100644
index 00000000000..346790eba12
--- /dev/null
+++ b/gcc/testsuite/g++.dg/ext/is_bounded_array.C
@@ -0,0 +1,38 @@
+// { dg-do compile { target c++11 } }
+
+#include <testsuite_tr1.h>
+
+using namespace __gnu_test;
+
+#define SA(X) static_assert((X),#X)
+
+#define SA_TEST_CONST(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)
+
+SA_TEST_CATEGORY(__is_bounded_array, int[2], true);
+SA_TEST_CATEGORY(__is_bounded_array, int[], false);
+SA_TEST_CATEGORY(__is_bounded_array, int[2][3], true);
+SA_TEST_CATEGORY(__is_bounded_array, int[][3], false);
+SA_TEST_CATEGORY(__is_bounded_array, float*[2], true);
+SA_TEST_CATEGORY(__is_bounded_array, float*[], false);
+SA_TEST_CATEGORY(__is_bounded_array, float*[2][3], true);
+SA_TEST_CATEGORY(__is_bounded_array, float*[][3], false);
+SA_TEST_CATEGORY(__is_bounded_array, ClassType[2], true);
+SA_TEST_CATEGORY(__is_bounded_array, ClassType[], false);
+SA_TEST_CATEGORY(__is_bounded_array, ClassType[2][3], true);
+SA_TEST_CATEGORY(__is_bounded_array, ClassType[][3], false);
+SA_TEST_CATEGORY(__is_bounded_array, int(*)[2], false);
+SA_TEST_CATEGORY(__is_bounded_array, int(*)[], false);
+SA_TEST_CATEGORY(__is_bounded_array, int(&)[2], false);
+SA_TEST_CONST(__is_bounded_array, int(&)[], false);
+
+// Sanity check.
+SA_TEST_CATEGORY(__is_bounded_array, ClassType, false);
+SA_TEST_CONST(__is_bounded_array, void(), false);
-- 
2.42.0

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

[Ken Matsui]

This patch optimizes the performance of the is_bounded_array trait
by dispatching to the new __is_bounded_array built-in trait.

libstdc++-v3/ChangeLog:

	* include/std/type_traits (is_bounded_array_v): Use __is_bounded_array
	built-in trait.

Signed-off-by: Ken Matsui <kmatsui@gcc.gnu.org>
---
 libstdc++-v3/include/std/type_traits | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/libstdc++-v3/include/std/type_traits b/libstdc++-v3/include/std/type_traits
index 677cd934b94..766f9a69445 100644
--- a/libstdc++-v3/include/std/type_traits
+++ b/libstdc++-v3/include/std/type_traits
@@ -3494,11 +3494,16 @@ template<typename _Ret, typename _Fn, typename... _Args>
   /// True for a type that is an array of known bound.
   /// @ingroup variable_templates
   /// @since C++20
+# if _GLIBCXX_USE_BUILTIN_TRAIT(__is_bounded_array)
+  template<typename _Tp>
+    inline constexpr bool is_bounded_array_v = __is_bounded_array(_Tp);
+# else
   template<typename _Tp>
     inline constexpr bool is_bounded_array_v = false;
 
   template<typename _Tp, size_t _Size>
     inline constexpr bool is_bounded_array_v<_Tp[_Size]> = true;
+# endif
 
   /// True for a type that is an array of unknown bound.
   /// @ingroup variable_templates
-- 
2.42.0