Optimize transform of vector<bool> for more predicates

benchmarks/src/vector_bool_transform.cpp

@@ -48,6 +48,7 @@ void common_args(auto bm) {
 
 BENCHMARK(transform_two_inputs_aligned<logical_and<>>)->Apply(common_args);
 BENCHMARK(transform_two_inputs_aligned<logical_or<>>)->Apply(common_args);
+BENCHMARK(transform_two_inputs_aligned<less<>>)->Apply(common_args);
 BENCHMARK(transform_one_input_aligned<logical_not<>>)->Apply(common_args);
 
 BENCHMARK_MAIN();

stl/inc/algorithm

@@ -4118,7 +4118,8 @@ _CONSTEXPR20 _OutIt transform(const _InIt _First, const _InIt _Last, _OutIt _Des
     const auto _ULast = _STD _Get_unwrapped(_Last);
     auto _UDest       = _STD _Get_unwrapped_n(_Dest, _STD _Idl_distance<_InIt>(_UFirst, _ULast));
 
-    if constexpr (_Is_vb_iterator<_InIt> && _Is_vb_iterator<_OutIt, true> && !is_same_v<_Map_vb_functor_t<_Fn>, void>) {
+    if constexpr (_Is_vb_iterator<decltype(_UFirst)> && _Is_vb_iterator<decltype(_UDest), true>
+                  && !is_void_v<_Map_vb_functor_t<_Fn>>) {
         if (_UFirst._Myoff == 0 && _UDest._Myoff == 0) {
             _UDest = _Transform_vbool_aligned(_UFirst, _ULast, _UDest, _Map_vb_functor_t<_Fn>{});
             _STD _Seek_wrapped(_Dest, _UDest);
@@ -4150,8 +4151,8 @@ _CONSTEXPR20 _OutIt transform(
     auto _UFirst2      = _STD _Get_unwrapped_n(_First2, _Count);
     auto _UDest        = _STD _Get_unwrapped_n(_Dest, _Count);
 
-    if constexpr (_Is_vb_iterator<_InIt1> && _Is_vb_iterator<_InIt2> && _Is_vb_iterator<_OutIt, true>
-                  && !is_same_v<_Map_vb_functor_t<_Fn>, void>) {
+    if constexpr (_Is_vb_iterator<decltype(_UFirst1)> && _Is_vb_iterator<decltype(_UFirst2)>
+                  && _Is_vb_iterator<decltype(_UDest), true> && !is_void_v<_Map_vb_functor_t<_Fn>>) {
         if (_UFirst1._Myoff == 0 && _UFirst2._Myoff == 0 && _UDest._Myoff == 0) {
             _UDest = _Transform_vbool_aligned(_UFirst1, _ULast1, _UFirst2, _UDest, _Map_vb_functor_t<_Fn>{});
             _STD _Seek_wrapped(_Dest, _UDest);

stl/inc/functional

@@ -268,8 +268,48 @@ struct _Bit_xnor {
     using is_transparent = int;
 };
 
+struct _Bit_imply {
+    template <class _Ty1, class _Ty2>
+    _NODISCARD constexpr auto operator()(_Ty1&& _Left, _Ty2&& _Right) const //
+        -> decltype(~_STD forward<_Ty1>(_Left) | _STD forward<_Ty2>(_Right)) {
+        return ~_STD forward<_Ty1>(_Left) | _STD forward<_Ty2>(_Right);
+    }
+
+    using is_transparent = int;
+};
+
+struct _Bit_cimply {
+    template <class _Ty1, class _Ty2>
+    _NODISCARD constexpr auto operator()(_Ty1&& _Left, _Ty2&& _Right) const //
+        -> decltype(_STD forward<_Ty1>(_Left) | ~_STD forward<_Ty2>(_Right)) {
+        return _STD forward<_Ty1>(_Left) | ~_STD forward<_Ty2>(_Right);
+    }
+
+    using is_transparent = int;
+};
+
+struct _Bit_nimply {
+    template <class _Ty1, class _Ty2>
+    _NODISCARD constexpr auto operator()(_Ty1&& _Left, _Ty2&& _Right) const //
+        -> decltype(_STD forward<_Ty1>(_Left) & ~_STD forward<_Ty2>(_Right)) {
+        return _STD forward<_Ty1>(_Left) & ~_STD forward<_Ty2>(_Right);
+    }
+
+    using is_transparent = int;
+};
+
+struct _Bit_cnimply {
+    template <class _Ty1, class _Ty2>
+    _NODISCARD constexpr auto operator()(_Ty1&& _Left, _Ty2&& _Right) const //
+        -> decltype(~_STD forward<_Ty1>(_Left) & _STD forward<_Ty2>(_Right)) {
+        return ~_STD forward<_Ty1>(_Left) & _STD forward<_Ty2>(_Right);
+    }
+
+    using is_transparent = int;
+};
+
 template <class _Ty>
-constexpr bool _Is_vbool_functor_arg = is_same_v<_Ty, void> || is_integral_v<_Ty>;
+constexpr bool _Is_vbool_functor_arg = is_void_v<_Ty> || is_integral_v<_Ty>;
 
 template <class _Ty>
 struct _Map_vb_functor<logical_and<_Ty>> {
@@ -306,6 +346,26 @@ struct _Map_vb_functor<equal_to<_Ty>> {
     using type = conditional_t<_Is_vbool_functor_arg<_Ty>, _Bit_xnor, void>;
 };
 
+template <class _Ty>
+struct _Map_vb_functor<less_equal<_Ty>> {
+    using type = conditional_t<_Is_vbool_functor_arg<_Ty>, _Bit_imply, void>;
+};
+
+template <class _Ty>
+struct _Map_vb_functor<greater_equal<_Ty>> {
+    using type = conditional_t<_Is_vbool_functor_arg<_Ty>, _Bit_cimply, void>;
+};
+
+template <class _Ty>
+struct _Map_vb_functor<less<_Ty>> {
+    using type = conditional_t<_Is_vbool_functor_arg<_Ty>, _Bit_cnimply, void>;
+};
+
+template <class _Ty>
+struct _Map_vb_functor<greater<_Ty>> {
+    using type = conditional_t<_Is_vbool_functor_arg<_Ty>, _Bit_nimply, void>;
+};
+
 template <class _Ty>
 struct _Map_vb_functor<logical_not<_Ty>> {
     using type = conditional_t<_Is_vbool_functor_arg<_Ty>, bit_not<>, void>;

tests/std/tests/GH_000625_vector_bool_optimization/test.cpp

@@ -76,12 +76,20 @@ CONSTEXPR20 void test_transform_helper(const size_t length) {
     bool or_expected_raw[size(source_raw)];
     bool xor_expected_raw[size(source_raw)];
     bool xnor_expected_raw[size(source_raw)];
+    bool l_expected_raw[size(source_raw)];
+    bool le_expected_raw[size(source_raw)];
+    bool g_expected_raw[size(source_raw)];
+    bool ge_expected_raw[size(source_raw)];
     bool not_expected_raw[size(source_raw)];
 
     transform(begin(source_raw), end(source_raw), begin(source2_raw), begin(and_expected_raw), logical_and<>{});
     transform(begin(source_raw), end(source_raw), begin(source2_raw), begin(or_expected_raw), logical_or<>{});
     transform(begin(source_raw), end(source_raw), begin(source2_raw), begin(xor_expected_raw), not_equal_to<>{});
     transform(begin(source_raw), end(source_raw), begin(source2_raw), begin(xnor_expected_raw), equal_to<>{});
+    transform(begin(source_raw), end(source_raw), begin(source2_raw), begin(l_expected_raw), less<>{});
+    transform(begin(source_raw), end(source_raw), begin(source2_raw), begin(le_expected_raw), less_equal<>{});
+    transform(begin(source_raw), end(source_raw), begin(source2_raw), begin(g_expected_raw), greater<>{});
+    transform(begin(source_raw), end(source_raw), begin(source2_raw), begin(ge_expected_raw), greater_equal<>{});
     transform(begin(source_raw), end(source_raw), begin(not_expected_raw), logical_not<>{});
 
     const vector<bool> source1(source_raw, source_raw + length);
@@ -91,18 +99,30 @@ CONSTEXPR20 void test_transform_helper(const size_t length) {
     vector<bool> or_expected(or_expected_raw, or_expected_raw + length);
     vector<bool> xor_expected(xor_expected_raw, xor_expected_raw + length);
     vector<bool> xnor_expected(xnor_expected_raw, xnor_expected_raw + length);
+    vector<bool> less_expected(l_expected_raw, l_expected_raw + length);
+    vector<bool> less_equal_expected(le_expected_raw, le_expected_raw + length);
+    vector<bool> greater_expected(g_expected_raw, g_expected_raw + length);
+    vector<bool> greater_equal_expected(ge_expected_raw, ge_expected_raw + length);
     vector<bool> not_expected(not_expected_raw, not_expected_raw + length);
 
     and_expected.resize(length + 3, false);
     or_expected.resize(length + 3, false);
     xor_expected.resize(length + 3, false);
     xnor_expected.resize(length + 3, false);
+    less_expected.resize(length + 3, false);
+    less_equal_expected.resize(length + 3, false);
+    greater_expected.resize(length + 3, false);
+    greater_equal_expected.resize(length + 3, false);
     not_expected.resize(length + 3, false);
 
     vector<bool> and_actual(length + 3);
     vector<bool> or_actual(length + 3);
     vector<bool> xor_actual(length + 3);
     vector<bool> xnor_actual(length + 3);
+    vector<bool> less_actual(length + 3);
+    vector<bool> less_equal_actual(length + 3);
+    vector<bool> greater_actual(length + 3);
+    vector<bool> greater_equal_actual(length + 3);
     vector<bool> not_actual(length + 3);
 
     // Also test combinations of vector<bool>::iterator and vector<bool>::const_iterator for the inputs.
@@ -157,6 +177,31 @@ CONSTEXPR20 void test_transform_helper(const size_t length) {
         // bit_xnor doesn't exist in the Standard
     }
 
+    {
+        const auto less_ret = transform(cfirst1, clast1, cfirst2, less_actual.begin(), less<>{});
+        assert(less_actual == less_expected);
+        assert(less_ret == less_actual.begin() + length);
+    }
+
+    {
+        const auto less_equal_ret = transform(cfirst1, clast1, cfirst2, less_equal_actual.begin(), less_equal<>{});
+        assert(less_equal_actual == less_equal_expected);
+        assert(less_equal_ret == less_equal_actual.begin() + length);
+    }
+
+    {
+        const auto greater_ret = transform(cfirst1, clast1, cfirst2, greater_actual.begin(), greater<>{});
+        assert(greater_actual == greater_expected);
+        assert(greater_ret == greater_actual.begin() + length);
+    }
+
+    {
+        const auto greater_equal_ret =
+            transform(cfirst1, clast1, cfirst2, greater_equal_actual.begin(), greater_equal<>{});
+        assert(greater_equal_actual == greater_equal_expected);
+        assert(greater_equal_ret == greater_equal_actual.begin() + length);
+    }
+
     {
         auto not_ret = transform(first1, last1, not_actual.begin(), logical_not<>{});
         assert(not_actual == not_expected);