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| author | Jonathan Wakely <jwakely@redhat.com> | 2024-06-28 11:14:39 +0100 |
|---|---|---|
| committer | Jonathan Wakely <redi@gcc.gnu.org> | 2024-06-28 20:19:02 +0100 |
| commit | fab60eaa94b50b1eea84f0d001004c851d4c781b (patch) | |
| tree | 7e8fba2796710d61bd56901d3cda9efa6f5cd693 | |
| parent | 03d3aeb0e0fa7dec9bd702cabf57ef73cdc32704 (diff) | |
| download | gcc-fab60eaa94b50b1eea84f0d001004c851d4c781b.zip gcc-fab60eaa94b50b1eea84f0d001004c851d4c781b.tar.gz gcc-fab60eaa94b50b1eea84f0d001004c851d4c781b.tar.bz2 | |
libstdc++: Extend std::equal memcmp optimization to std::byte [PR101485]
We optimize std::equal to memcmp for integers and pointers, which means
that std::byte comparisons generate bigger code than char comparisons.
We can't use memcmp for arbitrary enum types, because they could have an
overloaded operator== that has custom semantics, but we know that
std::byte doesn't do that.
libstdc++-v3/ChangeLog:
PR libstdc++/101485
* include/bits/stl_algobase.h (__equal_aux1): Check for
std::byte as well.
* testsuite/25_algorithms/equal/101485.cc: New test.
| -rw-r--r-- | libstdc++-v3/include/bits/stl_algobase.h | 6 | ||||
| -rw-r--r-- | libstdc++-v3/testsuite/25_algorithms/equal/101485.cc | 11 |
2 files changed, 16 insertions, 1 deletions
diff --git a/libstdc++-v3/include/bits/stl_algobase.h b/libstdc++-v3/include/bits/stl_algobase.h index 57ff2f7..dec1e4c 100644 --- a/libstdc++-v3/include/bits/stl_algobase.h +++ b/libstdc++-v3/include/bits/stl_algobase.h @@ -1257,7 +1257,11 @@ _GLIBCXX_END_NAMESPACE_CONTAINER typedef typename iterator_traits<_II1>::value_type _ValueType1; const bool __simple = ((__is_integer<_ValueType1>::__value #if _GLIBCXX_USE_BUILTIN_TRAIT(__is_pointer) - || __is_pointer(_ValueType1) + || __is_pointer(_ValueType1) +#endif +#if __glibcxx_byte && __glibcxx_type_trait_variable_templates + // bits/cpp_type_traits.h declares std::byte + || is_same_v<_ValueType1, byte> #endif ) && __memcmpable<_II1, _II2>::__value); return std::__equal<__simple>::equal(__first1, __last1, __first2); diff --git a/libstdc++-v3/testsuite/25_algorithms/equal/101485.cc b/libstdc++-v3/testsuite/25_algorithms/equal/101485.cc new file mode 100644 index 0000000..1fbb40a --- /dev/null +++ b/libstdc++-v3/testsuite/25_algorithms/equal/101485.cc @@ -0,0 +1,11 @@ +// { dg-options "-O0" } +// { dg-do compile { target c++17 } } +// { dg-final { scan-assembler "memcmp" } } + +#include <algorithm> +#include <cstddef> + +bool eq(std::byte const* p, std::byte const* q, unsigned n) +{ + return std::equal(p, p + n, q); +} |