Vendor import of llvm-project main llvmorg-15-init-16436-g18a6ab5b8d1f.vendor/llvm-project/llvmorg-15-init-16436-g18a6ab5b8d1f

1 files changed, 100 insertions, 35 deletions

diff --git a/libcxx/include/charconv b/libcxx/include/charconv
index 6a63e5fe9057..9f474ae711f3 100644
--- a/libcxx/include/charconv
+++ b/libcxx/include/charconv
@@ -117,32 +117,22 @@ from_chars_result from_chars(const char*, const char*, bool, int = 10) = delete;
 namespace __itoa
 {
 
-
 template <typename _Tp, typename = void>
-struct _LIBCPP_HIDDEN __traits_base
-{
-    using type = uint64_t;
-
-    static _LIBCPP_HIDE_FROM_ABI int __width(_Tp __v)
-    {
-        auto __t = (64 - std::__libcpp_clz(static_cast<type>(__v | 1))) * 1233 >> 12;
-        return __t - (__v < __table<>::__pow10_64[__t]) + 1;
-    }
-
-    static _LIBCPP_HIDE_FROM_ABI char* __convert(char* __p, _Tp __v)
-    {
-        return __itoa::__base_10_u64(__p, __v);
-    }
-
-    static _LIBCPP_HIDE_FROM_ABI decltype(__table<>::__pow10_64)& __pow() { return __table<>::__pow10_64; }
-};
+struct _LIBCPP_HIDDEN __traits_base;
 
 template <typename _Tp>
-struct _LIBCPP_HIDDEN
-    __traits_base<_Tp, decltype(void(uint32_t{declval<_Tp>()}))>
+struct _LIBCPP_HIDDEN __traits_base<_Tp, __enable_if_t<sizeof(_Tp) <= sizeof(uint32_t)>>
 {
     using type = uint32_t;
 
+    /// The width estimation using a log10 algorithm.
+    ///
+    /// The algorithm is based on
+    /// http://graphics.stanford.edu/~seander/bithacks.html#IntegerLog10
+    /// Instead of using IntegerLogBase2 it uses __libcpp_clz. Since that
+    /// function requires its input to have at least one bit set the value of
+    /// zero is set to one. This means the first element of the lookup table is
+    /// zero.
     static _LIBCPP_HIDE_FROM_ABI int __width(_Tp __v)
     {
         auto __t = (32 - std::__libcpp_clz(static_cast<type>(__v | 1))) * 1233 >> 12;
@@ -158,6 +148,61 @@ struct _LIBCPP_HIDDEN
 };
 
 template <typename _Tp>
+struct _LIBCPP_HIDDEN
+    __traits_base<_Tp, __enable_if_t<sizeof(_Tp) == sizeof(uint64_t)>> {
+  using type = uint64_t;
+
+  /// The width estimation using a log10 algorithm.
+  ///
+  /// The algorithm is based on
+  /// http://graphics.stanford.edu/~seander/bithacks.html#IntegerLog10
+  /// Instead of using IntegerLogBase2 it uses __libcpp_clz. Since that
+  /// function requires its input to have at least one bit set the value of
+  /// zero is set to one. This means the first element of the lookup table is
+  /// zero.
+  static _LIBCPP_HIDE_FROM_ABI int __width(_Tp __v) {
+    auto __t = (64 - std::__libcpp_clz(static_cast<type>(__v | 1))) * 1233 >> 12;
+    return __t - (__v < __table<>::__pow10_64[__t]) + 1;
+  }
+
+  static _LIBCPP_HIDE_FROM_ABI char* __convert(char* __p, _Tp __v) { return __itoa::__base_10_u64(__p, __v); }
+
+  static _LIBCPP_HIDE_FROM_ABI decltype(__table<>::__pow10_64)& __pow() { return __table<>::__pow10_64; }
+};
+
+
+#  ifndef _LIBCPP_HAS_NO_INT128
+template <typename _Tp>
+struct _LIBCPP_HIDDEN
+    __traits_base<_Tp, __enable_if_t<sizeof(_Tp) == sizeof(__uint128_t)> > {
+  using type = __uint128_t;
+
+  /// The width estimation using a log10 algorithm.
+  ///
+  /// The algorithm is based on
+  /// http://graphics.stanford.edu/~seander/bithacks.html#IntegerLog10
+  /// Instead of using IntegerLogBase2 it uses __libcpp_clz. Since that
+  /// function requires its input to have at least one bit set the value of
+  /// zero is set to one. This means the first element of the lookup table is
+  /// zero.
+  static _LIBCPP_HIDE_FROM_ABI int __width(_Tp __v) {
+    _LIBCPP_ASSERT(__v > numeric_limits<uint64_t>::max(), "The optimizations for this algorithm fail when this isn't true.");
+    // There's always a bit set in the upper 64-bits.
+    auto __t = (128 - std::__libcpp_clz(static_cast<uint64_t>(__v >> 64))) * 1233 >> 12;
+    _LIBCPP_ASSERT(__t >= __table<>::__pow10_128_offset, "Index out of bounds");
+    // __t is adjusted since the lookup table misses the lower entries.
+    return __t - (__v < __table<>::__pow10_128[__t - __table<>::__pow10_128_offset]) + 1;
+  }
+
+  static _LIBCPP_HIDE_FROM_ABI char* __convert(char* __p, _Tp __v) { return __itoa::__base_10_u128(__p, __v); }
+
+  // TODO FMT This pow function should get an index.
+  // By moving this to its own header it can be reused by the pow function in to_chars_base_10.
+  static _LIBCPP_HIDE_FROM_ABI decltype(__table<>::__pow10_128)& __pow() { return __table<>::__pow10_128; }
+};
+#endif
+
+template <typename _Tp>
 inline _LIBCPP_HIDE_FROM_ABI bool
 __mul_overflowed(unsigned char __a, _Tp __b, unsigned char& __r)
 {
@@ -271,6 +316,28 @@ __to_chars_itoa(char* __first, char* __last, _Tp __value, false_type)
         return {__last, errc::value_too_large};
 }
 
+#  ifndef _LIBCPP_HAS_NO_INT128
+template <>
+inline _LIBCPP_HIDE_FROM_ABI to_chars_result
+__to_chars_itoa(char* __first, char* __last, __uint128_t __value, false_type)
+{
+    // When the value fits in 64-bits use the 64-bit code path. This reduces
+    // the number of expensive calculations on 128-bit values.
+    //
+    // NOTE the 128-bit code path requires this optimization.
+    if(__value <= numeric_limits<uint64_t>::max())
+        return __to_chars_itoa(__first, __last, static_cast<uint64_t>(__value), false_type());
+
+    using __tx = __itoa::__traits<__uint128_t>;
+    auto __diff = __last - __first;
+
+    if (__tx::digits <= __diff || __tx::__width(__value) <= __diff)
+        return {__tx::__convert(__first, __value), errc(0)};
+    else
+        return {__last, errc::value_too_large};
+}
+#endif
+
 template <typename _Tp>
 inline _LIBCPP_HIDE_FROM_ABI to_chars_result
 __to_chars_integral(char* __first, char* __last, _Tp __value, int __base,
@@ -493,7 +560,6 @@ to_chars(char* __first, char* __last, _Tp __value)
 {
   using _Type = __make_32_64_or_128_bit_t<_Tp>;
   static_assert(!is_same<_Type, void>::value, "unsupported integral type used in to_chars");
-  static_assert(sizeof(_Tp) <= sizeof(int64_t), "128-bit integral support isn't available yet in to_chars");
   return std::__to_chars_itoa(__first, __last, static_cast<_Type>(__value), is_signed<_Tp>());
 }
 
@@ -504,7 +570,6 @@ to_chars(char* __first, char* __last, _Tp __value, int __base)
   _LIBCPP_ASSERT(2 <= __base && __base <= 36, "base not in [2, 36]");
 
   using _Type = __make_32_64_or_128_bit_t<_Tp>;
-  static_assert(sizeof(_Tp) <= sizeof(int64_t), "128-bit integral support isn't available yet in to_chars");
   return std::__to_chars_integral(__first, __last, static_cast<_Type>(__value), __base, is_signed<_Tp>());
 }
 
@@ -623,11 +688,11 @@ __from_chars_atoi(const char* __first, const char* __last, _Tp& __value)
 
     return __subject_seq_combinator(
         __first, __last, __value,
-        [](const char* _First, const char* _Last,
+        [](const char* __f, const char* __l,
            _Tp& __val) -> from_chars_result {
             __output_type __a, __b;
-            auto __p = __tx::__read(_First, _Last, __a, __b);
-            if (__p == _Last || !__in_pattern(*__p))
+            auto __p = __tx::__read(__f, __l, __a, __b);
+            if (__p == __l || !__in_pattern(*__p))
             {
                 __output_type __m = numeric_limits<_Tp>::max();
                 if (__m >= __a && __m - __a >= __b)
@@ -659,22 +724,22 @@ __from_chars_integral(const char* __first, const char* __last, _Tp& __value,
     return __subject_seq_combinator(
         __first, __last, __value,
         [](const char* __p, const char* __lastp, _Tp& __val,
-           int _Base) -> from_chars_result {
+           int __b) -> from_chars_result {
             using __tl = numeric_limits<_Tp>;
-            auto __digits = __tl::digits / log2f(float(_Base));
-            _Tp __a = __in_pattern(*__p++, _Base).__val, __b = 0;
+            auto __digits = __tl::digits / log2f(float(__b));
+            _Tp __x = __in_pattern(*__p++, __b).__val, __y = 0;
 
             for (int __i = 1; __p != __lastp; ++__i, ++__p)
             {
-                if (auto __c = __in_pattern(*__p, _Base))
+                if (auto __c = __in_pattern(*__p, __b))
                 {
                     if (__i < __digits - 1)
-                        __a = __a * _Base + __c.__val;
+                        __x = __x * __b + __c.__val;
                     else
                     {
-                        if (!__itoa::__mul_overflowed(__a, _Base, __a))
+                        if (!__itoa::__mul_overflowed(__x, __b, __x))
                             ++__p;
-                        __b = __c.__val;
+                        __y = __c.__val;
                         break;
                     }
                 }
@@ -682,11 +747,11 @@ __from_chars_integral(const char* __first, const char* __last, _Tp& __value,
                     break;
             }
 
-            if (__p == __lastp || !__in_pattern(*__p, _Base))
+            if (__p == __lastp || !__in_pattern(*__p, __b))
             {
-                if (__tl::max() - __a >= __b)
+                if (__tl::max() - __x >= __y)
                 {
-                    __val = __a + __b;
+                    __val = __x + __y;
                     return {__p, {}};
                 }
             }