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Use the new __has_feature(cxx_constexpr_string_builtins) for detection of the C-string intrinsics for constexpr support in std::char_traits. Thanks to Richard for the intrisic support.

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git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@293154 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Marshall Clow
2017-01-26 06:58:29 +00:00
parent 19cd3fd00f
commit f783971aa0
2 changed files with 7 additions and 14 deletions
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12
include/__string
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@@ -243,7 +243,7 @@ char_traits<char>::compare(const char_type* __s1, const char_type* __s2, size_t
{
if (__n == 0)
return 0;
#ifdef _LIBCPP_BUILTIN_MEMCMP_ISCONSTEXPR
#if __has_feature(cxx_constexpr_string_builtins)
return __builtin_memcmp(__s1, __s2, __n);
#elif _LIBCPP_STD_VER <= 14
return memcmp(__s1, __s2, __n);
@@ -265,7 +265,9 @@ char_traits<char>::find(const char_type* __s, size_t __n, const char_type& __a)
{
if (__n == 0)
return NULL;
#if _LIBCPP_STD_VER <= 14
#if __has_feature(cxx_constexpr_string_builtins)
return __builtin_char_memchr(__s, to_int_type(__a), __n);
#elif _LIBCPP_STD_VER <= 14
return (const char_type*) memchr(__s, to_int_type(__a), __n);
#else
for (; __n; --__n)
@@ -331,7 +333,7 @@ char_traits<wchar_t>::compare(const char_type* __s1, const char_type* __s2, size
{
if (__n == 0)
return 0;
#if __has_builtin(__builtin_wmemcmp)
#if __has_feature(cxx_constexpr_string_builtins)
return __builtin_wmemcmp(__s1, __s2, __n);
#elif _LIBCPP_STD_VER <= 14
return wmemcmp(__s1, __s2, __n);
@@ -351,7 +353,7 @@ inline _LIBCPP_CONSTEXPR_AFTER_CXX14
size_t
char_traits<wchar_t>::length(const char_type* __s) _NOEXCEPT
{
#if __has_builtin(__builtin_wcslen)
#if __has_feature(cxx_constexpr_string_builtins)
return __builtin_wcslen(__s);
#elif _LIBCPP_STD_VER <= 14
return wcslen(__s);
@@ -369,7 +371,7 @@ char_traits<wchar_t>::find(const char_type* __s, size_t __n, const char_type& __
{
if (__n == 0)
return NULL;
#if __has_builtin(__builtin_wmemchr)
#if __has_feature(cxx_constexpr_string_builtins)
return __builtin_wmemchr(__s, __a, __n);
#elif _LIBCPP_STD_VER <= 14
return wmemchr(__s, __a, __n);